JP2008134579A - Optical filter, polarizing plate, illumination device, and liquid crystal display device - Google Patents

Abstract

An optical filter, a polarizing plate, an illuminating device, and an image having the same color balance in front and oblique observations are used to display an image having the same color balance in front and oblique observations. Provided is a liquid crystal display device which can display and has a small dependence of contrast on a viewing angle.
The transmittance T ^F _{B, N in} the front direction at a wavelength of 440 nm, the average value T ^F _{B, 60} of the transmittance in the polar angle direction of 60 degrees at the wavelength of 440 nm, and the transmittance T ^F _{G, in} the front direction at a wavelength of 530 nm _{. N} , average value T ^F _{G, 60} of transmittance at a wavelength of 530 nm in a polar angle direction of 60 degrees, front transmittance T ^F _{R, N at} a wavelength of 620 nm, and average transmittance of a wavelength of 620 nm in a polar angle direction of 60 degrees An optical filter having a selective reflection band or a selective absorption band in which the relationship of the value T ^F _{R, 60} satisfies the formula [1].
(T ^F _{B, 60} / T ^F _{B, N} )> (T ^F _{G, 60} / T ^F _{G, N} ) ≈ (T ^F _{R, 60} / T ^F _{R, N} ) [1]
[Selection] Figure 3

Description

  The present invention relates to an optical filter, a polarizing plate, an illumination device, and a liquid crystal display device. Specifically, the present invention relates to an optical filter, a polarizing plate, an illuminating device, and a similar color in front and oblique observation that are used to display an image having the same color balance in front and oblique observation. The present invention relates to a liquid crystal display device that can display a balanced image and has a small viewing angle dependency of contrast.

  The liquid crystal display device includes a light source, two dichroic polarizers, and a liquid crystal cell disposed between the dichroic polarizers. Light from a light source such as a cold cathode tube, a hot cathode tube, LED (light emitting diode), EL (electroluminescence), blue light (wavelength 410 to 470 nm), green light (wavelength 520 to 580 nm), and red light ( Etc.) and the like emit white light. The light is converted into linearly polarized light by the first dichroic polarizer. The linearly polarized light is converted into linearly polarized light with the phase unchanged or inverted depending on the difference in voltage application or no voltage application in the liquid crystal cell. When the polarization transmission axis of the first dichroic polarizer and the polarization transmission axis of the second dichroic polarizer (also referred to as analyzer) are perpendicular, the linearly polarized light whose phase is inverted in the liquid crystal cell is The linearly polarized light that is transmitted through the second dichroic polarizer and has the same phase cannot pass through the second dichroic polarizer.

In general, a liquid crystal cell can invert the phase with respect to light incident at a polar angle of 0 degrees (that is, the phase is delayed by a half wavelength), but the phase is delayed with respect to light incident from an oblique direction. May not be completely reversed, and distortion may occur. The degree of distortion varies depending on the wavelength. As a result, the hue of the color image when observed from the front is different from the hue of the color image when observed from an oblique direction. For example, in a vertical alignment mode (hereinafter sometimes referred to as “VA mode”) liquid crystal panel, when white light is transmitted obliquely, the color coordinates (x, y) are white light at a polar angle of 0 degrees. Both are larger than the color coordinates (x _N , y _N ) when transmitted. That is, in the VA mode liquid crystal panel, when light is transmitted obliquely, the color shifts to reddish yellow.

In order to eliminate the difference in hue depending on the observation angle, Patent Document 1 includes a cholesteric liquid crystal layer having a selective reflection band at wavelengths λ ₁ to λ ₂ (λ ₁ <λ ₂ ) with respect to normal incident light. It has been proposed to arrange a collimator in the backlight system that satisfies λ ₀ <λ ₁ with respect to the maximum wavelength λ ₀ of the emission spectrum of the light source used in combination. The collimator described in Patent Document 1 has a function of aligning light traveling at various angles with only light traveling in the vertical direction. Therefore, light rays incident from an oblique direction are reflected by this collimator and are not transmitted.
JP 2002-169026 A (US Publication 2002/0036735)

Further, in Patent Document 2, it has transmission characteristics with respect to incident light in the visible light region in the normal direction, has a reflection wavelength band in the infrared region, and increases in angle (polar angle) with respect to the normal direction. It has been proposed that an infrared reflection layer (B) whose reflection wavelength band changes to the short wavelength side is arranged in a lighting device. Patent Document 2 discloses an infrared reflective layer (B) having a transmittance of light of 10% or less at a wavelength of 710 nm, 640 nm, or 610 nm at a polar angle of 45 degrees. Therefore, the red light incident obliquely is almost completely reflected or absorbed by the infrared reflection layer (B).
JP 2004-309618 A

  Liquid crystal display devices are classified into various display modes depending on the driving method of the liquid crystal in the liquid crystal cell. Among them, VA mode liquid crystal display devices and in-plane switching mode (hereinafter, sometimes referred to as “IPS mode”) liquid crystal display devices are currently mainstream for large display applications. A large display is particularly required to have a small difference between the hue of a color image when viewed from the front and the color image when viewed from an oblique direction.

  An object of the present invention is to provide an optical filter, an illuminating device, and an image having the same color balance in front and oblique observation, which are used to display an image having the same color balance in front and oblique observation. An object of the present invention is to provide a liquid crystal display device capable of displaying and having a small dependence of contrast on the viewing angle.

  When the liquid crystal display device disclosed in the above-mentioned patent document is observed from the front, the present inventors can obtain an image in which blue, green, and red are well-balanced. I noticed that it would be a greenish image.

  Therefore, the inventors of the present invention provide a peak wavelength of blue light from the front direction between a light source and a liquid crystal panel each having a wavelength showing emission intensity peaks in each wavelength region of blue light, green light, and red light. Shows only some selective reflection or selective absorption, and does not show selective reflection or selective absorption for green light peak wavelength and red light peak wavelength from the front direction, blue light peak wavelength from the oblique direction, green It has been found that by providing an optical filter that does not exhibit selective reflection or selective absorption with respect to the peak wavelength of light and the peak wavelength of red light, an image having the same color balance can be displayed in front and oblique observations.

In addition, the present inventors provide a peak wavelength of blue light from the front direction between a liquid crystal panel and a light source having a wavelength that shows a peak of emission intensity in each wavelength region of blue light, green light, and red light. , Does not show selective reflection or selective absorption for the peak wavelength of green light and peak wavelength of red light, and shows some selective reflection or selective absorption for the peak wavelength of green light and the peak wavelength of red light from an oblique direction. It has been found that by providing an optical filter on the backlight side of the liquid crystal panel, an image with the same color balance can be displayed in front and oblique observation.
Based on these findings, the present inventors have further studied and completed the present invention.

Thus, the present invention includes the following forms.
(1) Transmittance T ^F _{B, N in} the front direction at a wavelength of 440 nm, average value T ^F _{B, 60} of transmissivity in the direction of a polar angle of 60 degrees at a wavelength of 440 nm, and transmittance T ^F _{G, N in} the front direction at a wavelength of 530 nm , The average value T ^F _{G, 60} of the transmittance of the wavelength 530 nm in the polar angle 60 degrees direction, the transmittance T ^F _{R, N of} the wavelength 620 nm in the front direction, and the average value of the transmittance of the wavelength 620 nm in the polar angle 60 degrees direction An optical filter having a selective reflection band or a selective absorption band in which T ^F _{R, 60} satisfies the relationship of the formula [1].
(T ^F _{B, 60} / T ^F _{B, N} )> (T ^F _{G, 60} / T ^F _{G, N} ) ≈ (T ^F _{R, 60} / T ^F _{R, N} ) Equation [1]
(2) The optical filter having a selective reflection band or a selective absorption band in a wavelength range of 350 nm to 500 nm in the front direction.
(3) The above optical filter having at least one selective reflection band or selective absorption band in a wavelength range of 450 nm to 700 nm in a polar angle direction of 60 degrees.
(4) An illumination device including the optical filter and a light source.
(5) The said illuminating device with which the said light source has the peak of emitted light intensity in the wavelength range of 620 nm-680 nm.
(6) A liquid crystal display device comprising the illumination device and a liquid crystal panel.

(7) An output-side polarizing plate comprising an output-side polarizer and protective films laminated on both surfaces of the output-side polarizer,
Vertical alignment mode liquid crystal cell,
An incident-side polarizing plate comprising an incident-side polarizer and a protective film laminated on both surfaces of the incident-side polarizer, and a liquid crystal display device comprising a light source in this order,
In addition, one or two biaxial optical anisotropic plates are provided between the exit side polarizer and the liquid crystal cell and / or between the entrance side polarizer and the liquid crystal cell,
Furthermore, the optical filter is provided between the incident-side polarizer and the light source,
The biaxial optical anisotropic plate, the relationship _{n x> n y> n z} ( however, n _x is the in-plane slow axis direction of the refractive index, n _y is the direction perpendicular in the plane to the slow axis Refractive index, _nz is the refractive index in the thickness direction)
The protective film on the side near the liquid crystal cell in the output side polarizing plate, the liquid crystal cell in a state where no voltage is applied, the protective film on the side near the liquid crystal cell in the incident side polarizing plate, and all the biaxial optical differences. When the square plate is a laminated body, the laminated body has a retardation R ₀ when light having a wavelength of 550 nm is incident at an incident angle of 0 °, and light having a wavelength of 550 nm is incident at an incident angle of 40 °. And the retardation R ₄₀ satisfies the relationship of | R ₄₀ −R ₀ | ≦ 35 nm.
Liquid crystal display device.

(8) An output side polarizing plate comprising an output side polarizer and a protective film laminated on both surfaces of the output side polarizer,
In-plane switching mode liquid crystal cell,
An incident-side polarizing plate comprising an incident-side polarizer and a protective film laminated on both surfaces of the incident-side polarizer, and a liquid crystal display device comprising a light source in this order,
In addition, one or two biaxial optical anisotropic plates are provided between the exit side polarizer and the liquid crystal cell and / or between the entrance side polarizer and the liquid crystal cell,
Furthermore, the optical filter is provided between the incident-side polarizer and the light source,
The biaxial optical anisotropic plate, the relationship n _x> n _y and n _z> n _y (however, n _x is the in-plane slow axis direction of the refractive index, n _y is orthogonal plane to the slow axis Satisfying the refractive index in the direction of azimuth, _nz is the refractive index in the thickness direction)
The protective film on the side near the liquid crystal cell in the output side polarizing plate, the liquid crystal cell in a state where no voltage is applied, the protective film on the side near the liquid crystal cell in the incident side polarizing plate, and all the biaxial optical differences. When the square plate is a laminated body, the laminated body has a retardation R ₀ when light having a wavelength of 550 nm is incident at an incident angle of 0 °, and light having a wavelength of 550 nm is incident at an incident angle of 40 °. And the retardation R ₄₀ satisfies the relationship of | R ₄₀ −R ₀ | ≦ 35 nm.
Liquid crystal display device.

(9) An exit-side polarizing plate comprising an exit-side polarizer and a protective film laminated on both surfaces of the exit-side polarizer,
In-plane switching mode liquid crystal cell,
An incident-side polarizing plate comprising an incident-side polarizer and a protective film laminated on both surfaces of the incident-side polarizer, and a liquid crystal display device comprising a light source in this order,
Furthermore, an optical anisotropic member is provided between the exit side polarizer and the liquid crystal cell or between the entrance side polarizer and the liquid crystal cell,
Furthermore, the optical filter is provided between the incident-side polarizer and the light source,
The optical anisotropic _{member, n z ≧ n x> n} y first optical anisotropic plate of one satisfies the relationship, _{and, n x> n y ≧ n} z 1 sheets of second optically anisotropic satisfies the relationship Made of square plate,
A protective film near the liquid crystal cell in the output side polarizing plate, the liquid crystal cell in a state where no voltage is applied, a protective film near the liquid crystal cell in the incident side polarizing plate, and the optically anisotropic member are temporarily stacked. When the substrate is made into a body, the laminate has a retardation R ₀ when light having a wavelength of 550 nm is incident at an incident angle of 0 ° and a retardation R when light having a wavelength of 550 nm is incident at an incident angle of 40 °. ₄₀ satisfies the relationship of | R ₄₀ −R ₀ | ≦ 35 nm.
Liquid crystal display device.

(10) A polarizer and a protective film laminated on both sides of the polarizer,
Transmittance T ^P _{B, N in} the front direction at a wavelength of 440 nm, average value T ^P _{B, 60} of transmittance in a polar angle of 60 degrees direction at a wavelength of 440 nm, transmittance T ^P _{G, N in} the front direction at a wavelength of 530 nm, wavelength 530 nm The average value T ^P _{G, 60} of the transmittance in the polar angle direction of 60 degrees, the transmittance T ^P _{R, N in} the front direction at the wavelength of 620 nm, and the average value T ^P _R of the transmittance in the direction of the polar angle of 60 degrees at the wavelength of 620 nm. _{, 60} has a selective reflection band or a selective absorption band satisfying the relationship of the formula [2].
(T ^P _{B, 60} / T ^P _{B, N} )> (T ^P _{G, 60} / T ^P _{G, N} ) ≈ (T ^P _{R, 60} / T ^P _{R, N} ) Equation [2]
(11) It consists of a polarizer and protective films laminated on both sides of the polarizer, and when used with a light source, the protective film on the side close to the light source among the protective films is the optical filter. ,Polarizer.
(12) It consists of a polarizer and protective films laminated on both sides of the polarizer, and when used with a light source, the protective film on the side close to the light source of the protective film is an optical film and the optical film. A polarizing plate which is a laminate with a filter.
(13) The polarizing plate, wherein at least one of the protective films has optical anisotropy.
(14) A liquid crystal panel comprising the polarizing plate.
(15) A liquid crystal display device comprising the liquid crystal panel.

(16) An output-side polarizing plate comprising an output-side polarizer and a protective film laminated on both surfaces of the output-side polarizer,
Vertical alignment mode liquid crystal cell,
Incident side polarizing plate comprising the polarizing plate,
And a light source comprising a light source in this order,
Furthermore, between the during and / or entrance side polarizer and the liquid crystal cell and the outgoing side polarizing element and the liquid crystal cell, the relationship of _{n x> n y> n z} ( however, n _x is in the in-plane slow axis direction refractive index, n _y is the slow the refractive index in the direction perpendicular to the axis in the plane, n _z is the thickness direction of the one of the biaxial optical anisotropic plate satisfying the refractive index) or 2 Maisonae,
The protective film on the side near the liquid crystal cell in the output side polarizing plate, the liquid crystal cell in a state where no voltage is applied, the protective film on the side near the liquid crystal cell in the incident side polarizing plate, and all the biaxial optical differences. When the square plate is a laminated body, the laminated body has a retardation R ₀ when light having a wavelength of 550 nm is incident at an incident angle of 0 °, and light having a wavelength of 550 nm is incident at an incident angle of 40 °. And the retardation R ₄₀ satisfies the relationship of | R ₄₀ −R ₀ | ≦ 35 nm.
Liquid crystal display device.

(17) An output side polarizing plate comprising an output side polarizer and a protective film laminated on both surfaces of the output side polarizer,
In-plane switching mode liquid crystal cell,
Incident side polarizing plate comprising the polarizing plate,
And a light source comprising a light source in this order,
Further, the during the exit side polarizer and between and / or the entrance side polarizer and the liquid crystal cell and the liquid crystal cell, the relationship of n _x> n _y and n _z> n _y (however, n _x is plane slow axis direction of the refractive index, n _y is a refractive index in the direction perpendicular in the plane to the slow axis, n _z is one of the biaxial optical anisotropic plate satisfying the refractive index) in the thickness direction or With two,
The protective film on the side near the liquid crystal cell in the output side polarizing plate, the liquid crystal cell in a state where no voltage is applied, the protective film on the side near the liquid crystal cell in the incident side polarizing plate, and all the biaxial optical differences. When the square plate is a laminated body, the laminated body has a retardation R ₀ when light having a wavelength of 550 nm is incident at an incident angle of 0 °, and light having a wavelength of 550 nm is incident at an incident angle of 40 °. And the retardation R ₄₀ satisfies the relationship of | R ₄₀ −R ₀ | ≦ 35 nm.
Liquid crystal display device.

(18) An output side polarizing plate comprising an output side polarizer and a protective film laminated on both surfaces of the output side polarizer,
In-plane switching mode liquid crystal cell,
Incident side polarizing plate comprising the polarizing plate,
And a light source comprising a light source in this order,
Further, the during the exit side polarizer or between the incident side polarizer and the liquid crystal cell and the liquid crystal cell, n _z ≧ n _x> n first optical anisotropic plate of one that satisfies the relationship of _y And a second optical anisotropic plate satisfying the relationship of n _x > _ny ≧ _nz , or a multilayered or laminated structure,
A protective film near the liquid crystal cell in the output side polarizing plate, the liquid crystal cell in a state where no voltage is applied, a protective film near the liquid crystal cell in the incident side polarizing plate, and the optically anisotropic member are temporarily stacked. When the substrate is made into a body, the laminate has a retardation R ₀ when light having a wavelength of 550 nm is incident at an incident angle of 0 ° and a retardation R when light having a wavelength of 550 nm is incident at an incident angle of 40 °. ₄₀ satisfies the relationship of | R ₄₀ −R ₀ | ≦ 35 nm.
Liquid crystal display device.

  Conventional liquid crystal display devices are often yellowish when observed obliquely. This is because the light amounts of red and green when viewed from an oblique direction are relatively higher than the light amount of blue when compared with the light amount balance of blue, green and red when observed from the front. On the other hand, if the transmittance of light having a wavelength of 710 nm, 640 nm, or 610 nm incident from an oblique angle is set to 10% or less as in Patent Documents 1 and 2, the light quantity balance of blue, green, and red when viewed from the front is reduced. As a result, the amount of red light when observed from an oblique direction is relatively low compared to the amounts of blue and green light. As a result, when the liquid crystal display device is observed from an oblique direction, it tends to be bluish green or dark.

In the optical filter and the polarizing plate of the present invention, blue light is relatively difficult to transmit compared to green light and red light at a polar angle of 0 degrees (front direction). In an oblique direction (for example, a polar angle of 60 degrees), blue light, green light, and red light are transmitted to substantially the same degree. Further, the optical filter and the polarizing plate of the present invention transmit blue light, green light, and red light at approximately the same degree at a polar angle of 0 degrees (front direction), and green light in an oblique direction (for example, a polar angle of 60 degrees). In addition, red light is relatively difficult to transmit compared to blue light. In the optical filter and polarizing plate of the present invention having such transmission characteristics, any of the color coordinates (x, y) when white light is transmitted obliquely transmits white light at a polar angle of 0 degrees. It becomes smaller than the color coordinates (x _N , y _N ) at the time. When this optical filter or polarizing plate is combined with a liquid crystal cell, the color coordinate shift due to the viewing angle cancels out, so the blue, green, and red color balance when viewed from an oblique angle is the blue when viewed from the front. It can be adjusted to the same balance as that of green and red. As a result, when observed from an oblique direction, it is not yellowish or bluish, and the color reproduction range can be widened.

  In the liquid crystal display device of the present invention, the color balance of blue, green, and red when the display screen is observed obliquely becomes the same balance as the balance of blue, green, and red when observed from the front, When observed from an oblique direction, it does not appear reddish or bluish, and the color reproduction range of the display image is wide. In addition, the viewing angle dependency of contrast is small.

The figure which shows an example of the emission spectrum of a light source (four wavelength cold cathode tube). The figure which shows an example of the emission spectrum of another light source (RGB light emitting diode). The figure which shows an example of the wavelength distribution of the transmittance | permeability of the optical filter of 1st embodiment. It is a figure which shows the chromaticity coordinate (x, y) of the light which permeate | transmitted the isotropic film of the comparative example 1, and the liquid crystal panel. It is a figure which shows distribution of linear distance (DELTA) xy between the isotropic film of the comparative example 1, and the front direction chromaticity coordinate of the light which permeate | transmitted the liquid crystal panel, and diagonal direction chromaticity coordinate. It is a figure which shows the chromaticity coordinate (x, y) of the light which permeate | transmitted the optical filter and liquid crystal panel of Example 1. FIG. It is a figure which shows distribution of linear distance (DELTA) xy between the front direction chromaticity coordinate of the light which permeate | transmitted the optical filter of Example 1, and the liquid crystal panel, and diagonal direction chromaticity coordinate. It is a figure which shows the chromaticity coordinate (x, y) of the light which permeate | transmitted the optical filter and liquid crystal panel of Example 2. FIG. It is a figure which shows distribution of linear distance (DELTA) xy between the front direction chromaticity coordinate of the light which permeate | transmitted the optical filter of Example 2, and the liquid crystal panel, and diagonal direction chromaticity coordinate. It is a diagram for explaining the measuring method of retardation R _40. 6 is a diagram illustrating a configuration of a liquid crystal display device of Example 3. FIG. FIG. 6 is a diagram illustrating a configuration of a liquid crystal display device of Example 4. It is a figure which shows the structure of the liquid crystal display device of the comparative example 2. FIG. 10 is a diagram illustrating a configuration of a liquid crystal display device of Example 5. FIG. 10 is a diagram illustrating a configuration of a liquid crystal display device of Example 6. It is a figure which shows the structure of the liquid crystal display device of the comparative example 3. FIG. 10 is a diagram illustrating a configuration of a liquid crystal display device of Example 7.

Explanation of symbols

N: Wavelength distribution of transmittance in front direction A: Wavelength distribution of transmittance in oblique direction F: Triacetylcellulose film 3a, 4a, 5a, 6a, 7a: Output side polarizer 3b, 4b, 5b, 6b, 7b: Incident side polarizer 3A, 4A, 5A, 6A, 7A: Emission side polarizing plate 3B, 4B, 3C, 5B, 6B, 5C, 7B: Incident side polarizing plate 2A, 2B, 2b1, 2b2, 2C, 2D, 2E, 2F: Biaxial optical anisotropic plate 2G: Uniaxial optical anisotropic plate 3, 4, 5, 6, 7: Optical laminated plate B: Optical filter B
L: Light source VAC: VA mode liquid crystal cell IPSC: IPS mode liquid crystal cell Z: Isotropic film

[Optical filter]
The optical filter of the present invention has a transmittance T ^F _{B, N in} the front direction at a wavelength of 440 nm, an average value T ^F _{B, 60} of a transmittance in the polar angle 60 degrees direction at a wavelength of 440 nm, and a transmittance T in the front direction at a wavelength of 530 nm. ^F _{G, N} , average value T ^F _{G, 60} of transmittance at a wavelength of 530 nm in a polar angle direction of 60 degrees, front transmittance T ^F _{R, N at} a wavelength of 620 nm, and transmission of a wavelength of 620 nm in a polar angle direction of 60 degrees It has a selective reflection band or a selective absorption band in which the relationship of the average value T ^F _{R, 60} of the rate satisfies the formula [1].
(T ^F _{B, 60} / T ^F _{B, N} )> (T ^F _{G, 60} / T ^F _{G, N} ) ≈ (T ^F _{R, 60} / T ^F _{R, N} ) Equation [1]

  The selective reflection band or the selective absorption band is a band in which the transmittance is smaller than other parts in a specific wavelength range. More specifically, the selective reflection band or the selective absorption band is a band having a characteristic in which the transmittance is lower by 5% or more due to the internal structure of the optical filter in addition to the decrease in the transmittance due to the interface reflection on the optical filter surface. It is. In order to measure selective reflection characteristics or selective absorption characteristics excluding interface reflection, for example, the optical filter is placed in a liquid medium close to the average refractive index of the optical filter, and a measurement light beam is incident thereon to perform spectroscopy. It can be obtained by measuring the transmitted light intensity (referred to as intensity P), measuring the spectral transmission intensity (referred to as intensity Q) only with the medium in the same manner, and dividing the intensity P by the intensity Q.

The solid line N in FIG. 3 shows the wavelength dependence of the transmittance at a polar angle of 0 degrees. The selective reflection band or the selective absorption band is a part where the transmittance is smaller than the other part in the specific wavelength region as indicated by the solid line N. In FIG. 3, the selective reflection band or the selective absorption band forms a gentle valley like a parabola, but may form a rectangular or trapezoidal valley.
The wavelength range of the selective reflection band or the selective absorption band varies depending on the polar angle. The broken line A in FIG. 3 is the transmittance when observed from an oblique direction. When observed from an oblique direction, the selective reflection band or selective absorption band shifts to the short wavelength side as compared to the front direction.
The optical filter of the present invention uses this phenomenon to change the transmittance in the front direction and the oblique direction for each wavelength as described above.

The optical filter of the present invention only needs to have a selective reflection band or a selective absorption band that satisfies the formula [1]. The value of (T ^F _{G, 60} / T ^F _{G, N} ) and the value of (T ^F _{R, 60} / T ^F _{R, N} ) need to be substantially equal. Based on the value of (T ^F _{G, 60} / T ^F _{G, N} ), the value of (T ^F _{R, 60} / T ^F _{R, N} ) is usually within 5%, preferably within 3%. The value of (T ^F _{B, 60} / T ^F _{B, N} ) needs to be larger than the value of (T ^F _{G, 60} / T ^F _{G, N} ). Based on the value of (T ^F _{G, 60} / T ^F _{G, N} ) or the value of (T ^F _{R, 60} / T ^F _{R, N} ), (T ^F _{B, 60} / T ^F _{B, N} ) The value is usually 10% or more, preferably 20% or more.

  There are at least two embodiments having such a selective reflection band or selective absorption band. In the first embodiment, blue light is relatively difficult to transmit compared with green light and red light at a polar angle of 0 degrees (front direction), and blue light, green light, and red light at a polar angle of 60 degrees. In the second embodiment, blue light, green light, and red light are transmitted to approximately the same degree at a polar angle of 0 degrees (front direction). At 60 degrees, green light and red light are relatively difficult to transmit compared to blue light.

(First embodiment of optical filter)
In the optical filter according to the first embodiment, blue light is relatively less transmitted at a polar angle of 0 degrees (front direction) than green light and red light, and blue light, green light, and The red light is transmitted through almost the same level.
That is, the optical filter of the first embodiment has a selective reflection band or a selective absorption band in the wavelength range of blue light when observed from the front direction, and this selective reflection band or selective absorption band is observed at a polar angle of 60 degrees. When this occurs, the wavelength band shifts to the short wavelength side, and the transmittance of blue light becomes substantially the same as the transmittance of green light and red light.

  As shown in FIG. 1 or FIG. 2, the light source used for the liquid crystal display device emits light in the wavelength range of blue light 410 to 470 nm, the wavelength range of green light 520 to 580 nm, and the wavelength range of red light 600 to 660 nm. Has an intensity peak. FIG. 1 shows an emission spectrum of a 4-wavelength CCFL (cold cathode tube), and FIG. 2 shows an emission spectrum of an RGB light emitting diode (LED).

In the observation from the front direction, the optical filter of the first embodiment may have a selective reflection band or a selective absorption band in the entire wavelength range of preferably 350 nm to 500 nm, more preferably 410 to 470 nm. You may make it have a selective reflection band or a selective absorption band only in the partial range of the said wavelength range.
At this time, it is preferable that the wavelength indicating the peak of the light emission intensity of the light source is included in the selective reflection band or the selective absorption band.

In the optical filter of the first embodiment, the transmittance T ^F _{B, N in} the front direction at a wavelength of 440 nm is usually 50 to 80%, preferably 60 to 70%, and the transmittance at a polar angle of 60 degrees in the wavelength of 440 nm. The average value T ^F _{B, 60} is normally 80% or more, the transmittance T ^F _{G, N in} the front direction at a wavelength of 530 nm is usually 80% or more, and the transmittance in the polar angle 60 degree direction at a wavelength of 530 nm. The average value T ^F _{G, 60} is normally 80% or more, the transmittance T ^F _{R, N in} the front direction at a wavelength of 620 nm is usually 80% or more, and the transmittance in the polar angle 60 degree direction at a wavelength of 620 nm. The average value T ^F _{R, 60} is usually 80% or more.

(Second embodiment of optical filter)
The optical filter of the second embodiment transmits blue light, green light, and red light at approximately the same degree at a polar angle of 0 degrees (front direction), and the green light and red light are relative to blue light at a polar angle of 60 degrees. It is difficult to penetrate.
That is, the optical filter of the second embodiment has a selective reflection band or a selective absorption band in the wavelength range of green light and red light when observed from a direction with a polar angle of 60 degrees, and this selective reflection band or selective absorption. When the band is observed at a polar angle of 0 degree, the wavelength range shifts to the longer wavelength side, and the transmittance of green light and red light becomes substantially the same as the transmittance of blue light.

  As shown in FIG. 1 or FIG. 2, the light source used for the liquid crystal display device emits light in the wavelength range of blue light 410 to 470 nm, the wavelength range of green light 520 to 580 nm, and the wavelength range of red light 600 to 660 nm. Has an intensity peak.

The optical filter of the second embodiment may have a selective reflection band or a selective absorption band over the entire wavelength range of green light to red light (wavelength 450 to 700 nm) in observation from a direction with a polar angle of 60 degrees. However, it is preferable to have a selective reflection band or a selective absorption band respectively in the wavelength ranges corresponding to the wavelengths indicating the emission intensity peaks in the green light wavelength region and the red light wavelength region.
Moreover, it is preferable that it has a selective reflection band or a selective absorption band in the range of wavelengths 520 nm to 600 nm and wavelengths 620 nm to 900 nm, respectively, in the front direction.

In the optical filter of the second embodiment, the transmittance T ^F _{B, N in} the front direction at a wavelength of 440 nm is usually 80% or more, and the average value T ^F _{B, 60} of the transmittance in the polar angle direction of 60 degrees at the wavelength 440 nm. Is usually 80% or more, and the transmittance T ^F _{G, N in} the front direction at a wavelength of 530 nm is usually 80% or more, and the average value T ^F _{G, 60} of the transmittance in the polar angle 60 ° direction at a wavelength of 530 nm is 60%. but 50-80% usually, preferably 60% to 70%, the front direction of the transmittance T ^F _R wavelength _{620nm, N} is is usually 80% or more, polar angle direction of 60 degrees of the transmittance at a wavelength of 620nm The average value T ^F _{R, 60} is usually 50 to 80%, preferably 60 to 70%.

  The optical filter of the present invention is not limited by its structure as long as the transmittance characteristic changes according to the polar angle as described above. Examples of the optical filter of the present invention include those utilizing light interference. For example, a multilayer thin film (for example, a cold filter) in which inorganic oxides having different refractive indexes are alternately deposited; a thin film in which resin thin films having different refractive indexes are laminated; Obtained film; dielectric multilayer film; film obtained by uniaxial stretching of two types of resin films having different refractive indices, and further laminated by orthogonally crossing them; circularly polarized light including a resin layer having cholesteric regularity A reflection plate having a selective reflection band in a blue light region; a circularly polarized reflector having a right-handed product and a left-handed product laminated; a circularly-polarizing reflector 2 including a resin layer having cholesteric regularity in the same twist direction One obtained by laminating sheets through a half-wave plate; a grid polarizer or the like.

  Among these, a circularly polarized light reflector including a resin layer having cholesteric regularity (hereinafter sometimes referred to as a cholesteric resin layer) can relatively easily adjust a selective reflection band. Therefore, the optical filter of the present invention will be specifically described by exemplifying an optical filter using a circularly polarizing reflector including a resin layer having cholesteric regularity.

  The circularly polarized light reflector can be obtained by forming an alignment film on a sheet-like transparent substrate and further forming a resin layer having cholesteric regularity thereon.

(Transparent substrate)
The transparent substrate is not particularly limited as long as it is an optically transparent substrate. Examples of such a transparent substrate include a transparent resin film and a glass substrate. From the viewpoint of production efficiency, a long transparent resin film is preferable as the transparent substrate. The transparent resin film may be a single layer film or a multilayer film (laminate), but preferably has a total light transmittance of 80% or more at a thickness of 1 mm.

  Examples of the resin material for the transparent resin film include alicyclic structure-containing polymer resins, chain olefin polymers such as polyethylene and polypropylene, triacetyl cellulose, polyvinyl alcohol, polyimide, polyarylate, polyester, polycarbonate, polysulfone, and polyethersulfone. , Amorphous polyolefin, modified acrylic polymer, epoxy resin and the like. These can be used alone or in combination of two or more. Among these, an alicyclic structure-containing polymer resin or a chain olefin polymer is preferable, and an alicyclic structure-containing polymer resin is more preferable from the viewpoint of transparency, low hygroscopicity, dimensional stability, lightness, and the like. .

  The alicyclic structure-containing polymer resin includes (1) norbornene polymer, (2) monocyclic olefin polymer, (3) cyclic conjugated diene polymer, and (4) vinyl alicyclic hydrocarbon. Examples thereof include polymers and hydrogenated products thereof. Among these, norbornene-based polymers are preferable from the viewpoints of transparency and moldability.

  Examples of the norbornene-based polymer include, for example, a ring-opening polymer of a norbornene-based monomer, a ring-opening copolymer of a norbornene-based monomer and another monomer capable of ring-opening copolymerization, and hydrogenated products thereof; Examples include addition polymers, addition copolymers with other monomers copolymerizable with norbornene-based monomers, and hydrogenated products thereof. Among these, from the viewpoint of transparency, a ring-opening polymer hydrogenated product of a norbornene-based monomer is most preferable. The polymer having the alicyclic structure is selected from known polymers disclosed in, for example, JP-A No. 2002-321302.

  The resin material of the transparent resin film suitable for the present invention has a glass transition temperature of preferably 80 ° C. or higher, more preferably 100 to 250 ° C. A transparent resin film made of a resin material having a glass transition temperature in such a range is excellent in durability without causing deformation or stress during use at high temperatures.

  The molecular weight of the resin material of the transparent resin film suitable for the present invention is gel permeation chromatography (hereinafter abbreviated as “GPC”) using cyclohexane (toluene when the polymer resin is not dissolved) as a solvent. The weight average molecular weight (Mw) in terms of standard polyisoprene measured in (in terms of polystyrene when the solvent is toluene) is usually 10,000 to 100,000, preferably 25,000 to 80,000, more preferably 25. , 50,000 to 50,000. When the weight average molecular weight is in such a range, the mechanical strength and moldability of the film are highly balanced and suitable.

  The molecular weight distribution (weight average molecular weight (Mw) / number average molecular weight (Mn)) of the resin material of the transparent resin film suitable for the present invention is not particularly limited, but is usually 1.0 to 10.0, preferably 1.0 to 4.0, more preferably in the range of 1.2 to 3.5.

  The resin material of the transparent resin film suitable for the present invention has a content of a resin component having a molecular weight of 2,000 or less (that is, an oligomer component), preferably 5% by weight or less, more preferably 3% by weight or less, and still more preferably Is 2% by weight or less. When the amount of the oligomer component is large, fine convex portions are generated on the surface or thickness unevenness occurs, resulting in poor surface accuracy. In order to reduce the amount of oligomer components, the selection of polymerization catalyst and hydrogenation catalyst, conditions such as polymerization reaction and hydrogenation reaction, temperature conditions in the process of pelletizing resin as a molding material, etc. should be optimized. Good. The component amount of the oligomer can be measured by GPC using cyclohexane (toluene when the resin material does not dissolve).

  The thickness of the transparent substrate used in the present invention is not particularly limited. However, from the viewpoint of material cost and reduction in thickness and weight, the thickness is usually 1 to 1000 μm, preferably 5 to 300 μm, more preferably 30 to 100 μm. is there.

  In addition, the transparent substrate used in the present invention is preferably subjected to surface treatment in advance. By performing the surface treatment, the adhesion between the transparent substrate and the alignment film described later can be enhanced. Examples of the surface treatment include glow discharge treatment, corona discharge treatment, ultraviolet (UV) treatment, and flame treatment. It is also preferable to provide an adhesive layer (undercoat layer) on the transparent substrate in order to improve the adhesion between the transparent substrate and the alignment film.

(Alignment film)
The alignment film is formed on the surface of the transparent substrate in order to regulate the orientation of the resin layer having cholesteric regularity in one direction in the plane. The alignment film contains, for example, a polymer such as polyimide, polyvinyl alcohol, polyester, polyarylate, polyamideimide, or polyetherimide. The alignment film can be obtained by laminating a solution (composition for alignment film) containing such a polymer into a film, drying, and rubbing in one direction.

  Examples of the method of laminating the film include spin coating, roll coating, flow coating, printing, dip coating, casting film forming, bar coating, die coating, and gravure printing.

  The rubbing method is not particularly limited, and examples thereof include a method of rubbing the membrane surface in a certain direction with a roll made of a synthetic fiber such as nylon or a natural fiber such as cotton or a felt. In order to remove fine powder (foreign matter) generated during rubbing and to clean the surface of the alignment film, it is preferable to clean the formed alignment film with isopropyl alcohol or the like.

In addition to the rubbing method, a method of irradiating the surface of the alignment film with polarized ultraviolet light can also provide the alignment film with a function of regulating the alignment of the resin layer having cholesteric regularity in one direction in the plane.
The thickness of the alignment film is preferably 0.01 to 5 μm, and more preferably 0.05 to 1 μm.

(Resin layer with cholesteric regularity)
The cholesteric regularity is such that the molecular axes are aligned in a certain direction on one plane, but the direction of the molecular axis is slightly shifted in the next plane, and the angle is further shifted in the next plane. In this structure, the angle of the molecular axis is shifted (twisted) one after another in the normal direction of the plane. Such a structure in which the direction of the molecular axis is twisted is called a chiral structure. The normal line (chiral axis) of the plane is preferably substantially parallel to the thickness direction of the cholesteric resin layer.
The thickness of the cholesteric resin layer is preferably 0.1 μm to 10 μm, particularly preferably 0.5 μm to 5 μm.

<Material for forming cholesteric resin layer (1): liquid crystal polymer>
As a material for forming the cholesteric resin layer, first, a liquid crystal polymer is exemplified.

As this liquid crystal polymer, there is a polymer having a mesogenic structure. A mesogen is a conjugated linear atomic group that imparts liquid crystal alignment.
As a polymer having a mesogenic structure, a mesogenic group composed of a para-substituted cyclic compound or the like is bonded to a polymer main chain such as polyester, polyamide, polycarbonate, and polyesterimide directly or via a spacer portion that imparts flexibility. Having a structure; low molecular weight crystalline compound comprising a para-substituted cyclic compound or the like, directly or via a spacer portion comprising a conjugated atomic group in the polymer main chain of polyacrylate, polymethacrylate, polysiloxane, polymalonate, etc. Those having a structure in which a mesogenic part) is bonded.

  Examples of the spacer part include a polymethylene chain and a polyoxymethylene chain. The number of carbon atoms contained in the structural unit forming the spacer portion is appropriately determined depending on the chemical structure of the mesogen portion. In general, in the case of a polymethylene chain, the number of carbon atoms is 1 to 20, preferably 2 to 12, and in the case of a polyoxymethylene chain, the number of carbon atoms is 1 to 10, preferably 1 to 3. .

  Other examples of the liquid crystal polymer include a nematic liquid crystal polymer containing a low molecular chiral agent; a liquid crystal polymer incorporating a chiral component; a mixture of a nematic liquid crystal polymer and a cholesteric liquid crystal polymer. The liquid crystal polymer having a chiral component introduced therein is a liquid crystal polymer that itself functions as a chiral agent. In the mixture of the nematic liquid crystal polymer and the cholesteric liquid crystal polymer, the pitch of the chiral structure of the nematic liquid crystal polymer can be adjusted by changing the mixing ratio thereof.

  In addition, para-substituted cyclics that impart nematic orientation such as azomethine, azo, azoxy, ester, biphenyl, phenylcyclohexane, and para-substituted aromatic units such as bicyclohexane and para-substituted cyclohexyl units. Cholesteric regularity imparted by a method of introducing an appropriate chiral component or a low molecular chiral agent composed of a compound having an asymmetric carbon into a compound having a compound (Japanese Patent Laid-Open No. 55-21479, US) (See Japanese Patent No. 5332522 and the like). Examples of the terminal substituent at the para position in the para-substituted cyclic compound include a cyano group, an alkyl group, and an alkoxyl group.

  As the chiral agent to be introduced or contained in the liquid crystal polymer, conventionally known ones can be used. Examples thereof include a chiral monomer described in JP-A-6-281814, a chiral agent described in JP-A-8-209127, and a photoreactive chiral compound described in JP-A-2003-131187.

  Further, as the chiral agent, in order to avoid an unintended change of the phase transition temperature due to the addition of the chiral agent, the chiral agent itself exhibits liquid crystallinity. Further, from the viewpoint of economy, those having a large HTP (= 1 / P · c), which is an index representing the efficiency of twisting the liquid crystal polymer, are preferable. Here, P represents the pitch length of the chiral structure, and c represents the concentration of the chiral agent. The pitch length of the chiral structure is a distance in the chiral axis direction until the angle of the molecular axis in the chiral structure gradually shifts as it advances along the plane and then returns to the original molecular axis direction again.

<Material for Forming Cholesteric Resin Layer (2): Polymerizable Composition>
Suitable materials for forming the cholesteric resin layer include a polymerizable composition containing a polymerizable liquid crystal compound, preferably a polymerizable composition containing a polymerizable liquid crystal compound, a polymerization initiator, and a chiral agent. As a method of forming a cholesteric resin layer using this material, a coating liquid in which a polymerizable liquid crystal compound, a polymerization initiator, a chiral agent, and a surfactant, an alignment regulator, etc. are dissolved in a solvent as required is obtained. There is a method of laminating this on a substrate in the form of a film, drying, and polymerizing the dried film.

As the polymerizable liquid crystal compound, a rod-like liquid crystal compound is preferably used.
Examples of the rod-like liquid crystal compound include a compound represented by the chemical formula [6].
R ¹ -B ¹ -A ¹ -B ³ -MB ⁴ -A ² -B ² -R ² formula [6]
In addition, A ¹ and A ² in the chemical formula [6] are spacer groups as described later, but this spacer group is omitted, and B ¹ and B ³ or B ⁴ and B ² are directly bonded. Also good. In the chemical formula [6], R ¹ and R ² represent a polymerizable group.

B ¹ , B ² , B ³ and B ⁴ each independently represents a single bond or a divalent linking group. Also, B ^3, at least one of B ⁴ is preferably a -O-CO-O-.
A ¹ and A ² represent a spacer group having 1 to 20 carbon atoms. Examples of the spacer group include a polymethylene group and a polyoxymethylene group.

  M represents a mesogenic group. The material for forming the mesogenic group M is not particularly limited, but azomethines, azoxys, cyanobiphenyls, cyanophenyl esters, benzoic acid esters, cyclohexanecarboxylic acid phenyl esters, cyanophenylcyclohexanes, cyano-substituted phenylpyrimidines Alkoxy-substituted phenylpyrimidines, phenyldioxanes, tolanes and alkenylcyclohexylbenzonitriles are preferably used.

The polymerization initiator includes a thermal polymerization initiator and a photopolymerization initiator, and a photopolymerization initiator is preferred because the polymerization reaction is fast.
As photopolymerization initiators, polynuclear quinone compounds (US Pat. Nos. 3,046,127 and 2,951,758), oxadiazole compounds (US Pat. No. 4,212,970), α-carbonyl compounds (US Pat. No. 2,367,661, US Pat. No. 2,367,670) ), Acyloin ether (US Pat. No. 2,448,828), α-hydrocarbon substituted aromatic acyloin compound (US Pat. No. 2,722,512), combination of triarylimidazole dimer and p-aminophenyl ketone (US Pat. No. 3,549,367) , Acridine and phenazine compounds (Japanese Patent Laid-Open No. 60-105667, US Pat. No. 4,239,850).

  As the chiral agent to be contained in the polymerizable composition, those described in JP-A No. 2003-66214, JP-A No. 2003-313187, US Pat. No. 6,468,444, WO 98/00428, and the like are appropriately used. However, a material having a large HTP, which is an index representing the efficiency of twisting the liquid crystal compound, is preferable from the viewpoint of economy. HTP is represented by the formula: HTP = 1 / P · c. Here, P represents the pitch length of the chiral structure, and c represents the concentration of the chiral agent. In order to avoid an unintended change in the phase transition temperature due to the addition of the chiral agent, it is preferable to use a chiral agent that exhibits liquid crystallinity.

  A surfactant can be used to adjust the surface tension of the coating solution and the film of the coating solution before polymerization. Particularly preferred is a nonionic surfactant, and an oligomer having a molecular weight of about several thousand is preferred. Examples of such a surfactant include KH-40 manufactured by Seimi Chemical Co., Ltd.

  The alignment modifier is for controlling the alignment state of the air-side surface of the cholesteric resin layer formed on the substrate, and may also serve as the surfactant. Is used. As such a resin, polyvinyl alcohol, polyvinyl butyral, or a modified product thereof is used, but not limited thereto.

  As a solvent used for preparing the coating solution, an organic solvent is preferably used. Examples of the organic solvent include ketones, alkyl halides, amides, sulfoxides, heterocyclic compounds, hydrocarbons, esters, and ethers. In particular, ketones are preferable in consideration of environmental load. Two or more organic solvents may be used in combination.

  In order to laminate the coating liquid into a film, a known method such as an extrusion coating method, a direct gravure coating method, a reverse gravure coating method, a die coating method, or the like can be performed.

  The cholesteric resin layer used in the present invention is preferably a non-liquid crystalline resin layer. This is because the cholesteric regularity does not change depending on the ambient temperature, electric field, or the like when it is non-liquid crystalline. The non-liquid crystalline cholesteric resin layer can be obtained by selecting a polymerizable composition containing a polymerizable liquid crystal compound having two or more polymerizable groups and polymerizing it. By the polymerizable liquid crystal compound having two or more polymerizable groups, a relatively rigid cross-linked structure is introduced into the cholesteric resin, and a resin that does not produce liquid crystallinity is obtained.

When light is incident on the resin layer having cholesteric regularity, only the left-handed or right-handed circularly polarized light in the specific wavelength region is reflected. Light other than the reflected circularly polarized light is transmitted. The specific wavelength region where the circularly polarized light is reflected is called a selective reflection band.
White light incident on the cholesteric resin layer of the circularly polarizing reflector at a polar angle θ ₁ is refracted on the surface of the cholesteric resin layer, passes through the cholesteric resin layer at a refraction angle θ ₂ , and has a pitch length P corresponding to the wavelength λ. One circularly polarized light is reflected at the reflection angle θ ₂ by the cholesteric resin layer, and is refracted at the surface of the cholesteric resin layer and emitted at the emission angle θ ₁ . Refraction is performed according to Snell's law.

When the helical axis representing the rotational axis when the molecular axis is twisted in the chiral structure and the normal line of the cholesteric resin layer are parallel, the pitch length P of the chiral structure and the wavelength λ of the circularly polarized light reflected are expressed by the formula [ 3] and formula [4].
λ _c = n × P × cos θ ₂ formula [3]
_{n o × P × cosθ 2 ≦} λ ≦ n e × P × cosθ 2 Equation [4]
Wherein, n _o represents the minor axis direction of the refractive index of the rod-like liquid crystal compound, n _e represents the refractive index of the long axis of the rod-like liquid crystal _{compound, n = (n e + n} o) / 2, P is chiral structure Represents the pitch length.

That is, the center wavelength λ _c of the selective reflection band depends on the pitch length P of the chiral structure in the cholesteric resin layer. By changing the pitch length of this chiral structure, the selected wavelength band can be changed.
In order to provide a selective reflection band when observed from the front direction at a wavelength of 350 to 500 nm, the pitch length is preferably adjusted to 200 to 360 nm, more preferably 220 to 330 nm.

The pitch length is preferably adjusted to 260 to 500 nm, more preferably 280 to 470 nm in order to provide a selective reflection band at a wavelength of 450 to 700 nm when observed from the direction of a polar angle of 60 degrees.
In order to provide a selective reflection band at a wavelength of 520 to 600 nm when observed from the front direction, the pitch length is preferably adjusted to 300 to 430 nm, more preferably 320 to 400 nm.
In order to provide a selective reflection band when observed from the front direction at a wavelength of 620 to 900 nm, the pitch length is preferably adjusted to 360 to 640 nm, more preferably 380 to 600 nm.

Note that the pitch length is the distance in the chiral axis direction until the angle of the molecular axis gradually shifts in the chiral structure as it advances along the plane and then returns to the original molecular axis direction again.
Further, the reflectance increases according to the number of stacked chiral structures. In order to adjust the reflectance, the number of layers of the chiral structure, that is, the thickness is adjusted. Since the width of the selective reflection band is dependent on the distribution of the difference and the pitch length of n _o and n _e, selects the manufacturing easy suitable liquid crystal compounds.

〔Polarizer〕
The polarizing plate of the present invention comprises a polarizer and a protective film laminated on both sides of the polarizer,
Transmittance T ^P _{B, N in} the front direction at a wavelength of 440 nm, average value T ^P _{B, 60} of transmissivity in the polar angle of 60 degrees direction at a wavelength of 440 nm, transmittance T ^P _{G, N in} the front direction at a wavelength of 530 nm, and wavelength of 530 nm The average value T ^P _{G, 60} of the transmittance in the polar angle direction of 60 degrees, the transmittance T ^P _{R, N in} the front direction at the wavelength of 620 nm, and the average value T ^P _R of the transmittance in the direction of the polar angle of 60 degrees at the wavelength of 620 nm. _{, 60} have a selective reflection band or selective absorption band satisfying the expression [2].
(T ^P _{B, 60} / T ^P _{B, N} )> (T ^P _{G, 60} / T ^P _{G, N} ) ≈ (T ^P _{R, 60} / T ^P _{R, N} ) Equation [2]

The polarizing plate of this invention should just have the selective reflection zone or selective absorption zone which satisfy | fills Formula [2]. The value of (T ^P _{G, 60} / T ^P _{G, N} ) and the value of (T ^P _{R, 60} / T ^P _{R, N} ) need to be approximately equal. Based on the value of (T ^P _{G, 60} / T ^P _{G, N} ), the value of (T ^P _{R, 60} / T ^P _{R, N} ) is usually within 5%, preferably within 3%. The value of (T ^P _{B, 60} / T ^P _{B, N} ) needs to be larger than the value of (T ^P _{G, 60} / T ^P _{G, N} ). _{^{(T P G, 60 / T}} P G, N) value or a _{^{(T F R, 60 / T}} F R, N) based on the value of the _{^{(T P B, 60 / T}} P B, N) The value is usually 10% or more, preferably 20% or more.

  There are at least two embodiments having such a selective reflection band or selective absorption band. In the first embodiment, blue light is relatively difficult to transmit compared with green light and red light at a polar angle of 0 degrees (front direction), and blue light, green light, and red light at a polar angle of 60 degrees. In the second embodiment, blue light, green light, and red light are transmitted to approximately the same degree at a polar angle of 0 degrees (front direction). At 60 degrees, green light and red light are relatively difficult to transmit compared to blue light.

(First embodiment of polarizing plate)
In the polarizing plate of the first embodiment, blue light is relatively difficult to transmit compared to green light and red light at a polar angle of 0 degrees (front direction), and blue light, green light, and so on at a polar angle of 60 degrees. The red light is transmitted through almost the same level.
That is, the polarizing plate of the first embodiment has a selective reflection band or a selective absorption band in the wavelength range of blue light when observed from the front direction, and this selective reflection band or selective absorption band is observed at a polar angle of 60 degrees. When this occurs, the wavelength band shifts to the short wavelength side, and the transmittance of blue light becomes substantially the same as the transmittance of green light and red light.

In the observation from the front direction, the polarizing plate of the first embodiment may have a selective reflection band or a selective absorption band in the entire wavelength range of preferably 350 nm to 500 nm, more preferably 410 to 470 nm, You may make it have a selective reflection band or a selective absorption band only in the partial range of the said wavelength range.
At this time, it is preferable that the wavelength indicating the peak of the light emission intensity of the light source is included in the selective reflection band or the selective absorption band.

(Second embodiment of polarizing plate)
The polarizing plate of the second embodiment transmits blue light, green light, and red light at approximately the same degree at a polar angle of 0 degrees (front direction), and the green light and red light are relative to blue light at a polar angle of 60 degrees. It is difficult to penetrate.
That is, the polarizing plate of the second embodiment has a selective reflection band or a selective absorption band in the wavelength range of green light and red light, respectively, when observed from a direction with a polar angle of 60 degrees, and this selective reflection band or selective absorption. When the band is observed at a polar angle of 0 degree, the wavelength range shifts to the longer wavelength side, and the transmittance of green light and red light becomes substantially the same as the transmittance of blue light.

The polarizing plate of the second embodiment may have a selective reflection band or a selective absorption band over the entire wavelength range of green light to red light (wavelength 450 to 700 nm) in observation from a direction with a polar angle of 60 degrees. However, it is preferable to have a selective reflection band or a selective absorption band respectively in the wavelength ranges corresponding to the wavelengths showing the emission intensity peaks in the green light wavelength region and the red light wavelength region.
Moreover, it is preferable that it has a selective reflection band or a selective absorption band in the range of wavelengths 520 nm to 600 nm and wavelengths 620 nm to 900 nm, respectively, in the front direction.

The polarizing plate of the present invention is not limited by its structure as long as the transmittance characteristics change according to the polar angle as described above.
As a configuration example 1 of the polarizing plate of the present invention, a polarizer and a protective film laminated on both surfaces of the polarizer, the protective film laminated on the side close to the light source among the protective films is the optical filter. Some are listed.

  The polarizer constituting the polarizing plate of the present invention transmits one of two linearly polarized light intersecting at right angles. For example, a hydrophilic polymer film such as a polyvinyl alcohol film or an ethylene vinyl acetate partially saponified film adsorbed a dichroic substance such as iodine or a dichroic dye and uniaxially stretched, the hydrophilic polymer film Examples include uniaxially stretched and dichroic substances adsorbed, and polyene oriented films such as polyvinyl alcohol dehydrated products and polyvinyl chloride dehydrochlorinated products. Other examples include a polarizer having a function of separating polarized light such as grid polarizer and multilayer polarizer into reflected light and transmitted light. Of these, a polarizer containing polyvinyl alcohol is preferred. Although the polarization degree of the polarizer used for this invention is not specifically limited, Preferably it is 98% or more, More preferably, it is 99% or more. The average thickness of the linear polarizer is preferably 5 μm to 80 μm.

  In this structural example 1, the protective film laminated | stacked on the side close | similar to a light source among the protective films used for a polarizing plate is the said optical filter, and the remaining protective films are conventionally used for protection of a polarizing plate. It is an optical film. As a conventional optical film for protecting a polarizing plate, a thermoplastic resin film is usually used. Examples of the thermoplastic resin include alicyclic structure-containing polymer resins, chain olefin polymers such as polyethylene and polypropylene, triacetyl cellulose, polyvinyl alcohol, polyimide, polyarylate, polyester, polycarbonate, polysulfone, polyethersulfone, and amorphous. Examples include polyolefins, modified acrylic polymers, epoxy resins, and methacrylic resins.

Further, as another configuration example 2 of the polarizing plate of the present invention, a polarizer and a protective film laminated on both sides of the polarizer, a protective film laminated on the side close to the light source among the protective films, What is a laminated body which consists of an optical film and the said optical filter is mentioned.
In this structural example 2, the protective film laminated | stacked on the side close | similar to a light source among the protective films used for this polarizing plate is the said laminated body, and the remaining protective films are conventionally used for protection of a polarizing plate. It is an optical film. What was illustrated as an optical film of the said structural example 1 can be used as an optical film used for a laminated body, and the conventional optical film for polarizing plate protection.

As a polarizing plate of the suitable form of this invention, what has at least one of the said protective film has optical anisotropy can be mentioned. The film having optical anisotropy is not particularly limited as long as at least one of the main refractive indexes _nx , _ny and _nz is different. For example, _nx > _ny > _{nz, nx} > _ny = _nz , _nx > _nz > _ny , _nx = _nz > _ny , _nz > _nx > _ny , _nx = n _y> n _z, and the like satisfy the relation such as _{n z> n x = n y} .

[Lighting device]
The illumination device of the present invention includes the optical filter of the present invention and a light source such as a cold cathode tube, a hot cathode tube, a light emitting diode, and electroluminescence. The light source preferably has a light emission intensity peak in the wavelength range of 620 nm to 680 nm. Between the light source and the optical filter, a light diffusing element, a condensing element, a brightness enhancement film or the like may be interposed, and a light reflecting element may be disposed behind the light source. In the illuminating device of the present invention, the light emitted from the light source is transmitted through the optical filter of the present invention with a light transmittance that satisfies the relationship of the formula [1].

  The light reflecting element is an element that can reflect light. Specifically, a reflecting plate provided with a reflective metal film or a white film can be used. The light diffusing element is an element that scatters light into diffused light to eliminate the in-plane distribution of luminance. Specifically, a light diffusing material such as silicone beads dispersed in a transparent substrate (sometimes referred to as a light diffusing plate), or a light diffusing material applied to the surface of a transparent substrate (referred to as a light diffusing sheet) In some cases). Examples of the condensing element include a prism sheet and a microlens.

[Liquid Crystal Display]
(First embodiment of liquid crystal display device)
The liquid crystal display device of the first embodiment of the present invention includes the illumination device of the present invention and a liquid crystal panel. The optical filter is preferably disposed between the light source and the liquid crystal panel. The liquid crystal panel includes an incident side polarizer, a liquid crystal cell, and an output side polarizer (analyzer). The above-described polarizer can be used for the incident side or output side polarizer. Polarizer performance may change due to moisture absorption. In order to prevent this, a protective film is usually bonded to both sides of the incident side polarizer or analyzer. The protective film bonded to the analyzer may be provided with an antireflection layer, an antifouling layer, an antiglare layer, and the like.

A liquid crystal cell is filled with a liquid crystal substance between two glass substrates provided with transparent electrodes facing each other with a gap of several μm, and a voltage is applied to this electrode to change the alignment state of the liquid crystal and pass through this. The amount of light to be controlled is controlled.
The liquid crystal cell is classified according to a method (operation mode) for changing the alignment state of the liquid crystal substance. For example, a TN (Twisted Nematic) type liquid crystal cell, a STN (Super Twisted Nematic) type liquid crystal cell, or a HAN (Hybrid Alignment Nematic) type. Liquid crystal cells, IPS (In Plane Switching) type liquid crystal cells, VA (Vertical Alignment) type liquid crystal cells, MVA (Multi-domain Vertical Alignment type liquid crystal cells, OCB (Optical Compensated Bend) type liquid crystal cells, etc.

(Second Embodiment of Liquid Crystal Display Device)
The liquid crystal display device according to the second embodiment of the present invention includes an emission side polarizing plate, a vertical alignment mode liquid crystal cell, an incident side polarizing plate, and a light source in this order.
The exit-side polarizing plate includes an exit-side polarizer and a protective film laminated on both surfaces of the exit-side polarizer. The incident side polarizing plate includes an incident side polarizer and a protective film laminated on both surfaces of the incident side polarizer.

In the liquid crystal display device of the second embodiment, further, between and / or between the incident side polarizer and the liquid crystal cell and the outgoing side polarizing element and the liquid crystal cell, the relationship of _{n x> n y> n z} ( where n _x is the in-plane slow axis direction of the refractive index, n _y is the refractive index in the direction orthogonal in the plane to the slow axis, n _z is a biaxial optical anisotropic plate satisfying the refractive index) in the thickness direction One or two are provided.

  As a mode of disposing the biaxial optical anisotropic plate, a mode in which one sheet is disposed only between the output side polarizer and the liquid crystal cell, and a mode in which one sheet is disposed only between the incident side polarizer and the liquid crystal cell. A mode in which one sheet is disposed between the output side polarizer and the liquid crystal cell, and a mode in which two sheets are disposed only between the output side polarizer and the liquid crystal cell. A mode in which two sheets are disposed only between the polarizer and the liquid crystal cell, a mode in which two sheets are disposed between the output side polarizer and the liquid crystal cell, and between the incident side polarizer and the liquid crystal cell, and the output side polarizer. A mode in which one sheet is disposed between the liquid crystal cell and two sheets are disposed between the incident side polarizer and the liquid crystal cell, and two sheets are disposed between the output side polarizer and the liquid crystal cell. A mode in which one sheet is arranged between the liquid crystal cells is included.

The biaxial optical anisotropic plate used in the liquid crystal display device of the second embodiment is a transparent film. The transparent film can be used without particular limitation as long as the total light transmittance is 80% or more when the film is 1 mm thick.
A material for forming the biaxial optical anisotropic plate is not particularly limited, but a thermoplastic resin is preferable. As thermoplastic resins, polycarbonate resin, polyether sulfone resin, polyethylene terephthalate resin, polyimide resin, polymethyl methacrylate resin, polysulfone resin, polyarylate resin, polyethylene resin, polyvinyl chloride resin, diacetyl cellulose, triacetyl cellulose, polystyrene resin , Polyacrylic resins, olefin polymers having an alicyclic structure, and the like. Among these, the olefin polymer having an alicyclic structure is preferably used because the display image of the liquid crystal display device of the present invention can have the same color balance in front and oblique observation. be able to.

Examples of the olefin polymer having an alicyclic structure include norbornene resins, monocyclic olefin resins, cyclic conjugated diene resins, vinyl alicyclic hydrocarbon resins, and hydrides thereof. Among these, norbornene-based resins can be suitably used because of their good transparency and moldability.
The norbornene-based resin includes a ring-opening polymer of a monomer having a norbornene structure, a ring-opening copolymer of a monomer having a norbornene structure and another monomer, a hydride thereof, or a monomer having a norbornene structure. An addition copolymer of a monomer, an addition copolymer of a monomer having a norbornene structure and another monomer, a hydride thereof, or the like can be given.

  As the film made of the thermoplastic resin, a film obtained by a known molding method can be employed. Examples thereof include those obtained by a hot melt molding method and a solution casting method. From the viewpoint of reducing the volatile components in the film, it is preferable to use one obtained by a hot melt molding method.

  The hot melt molding method can be further classified into a melt extrusion molding method, a press molding method, an inflation method, an injection molding method, a blow molding method, a stretch molding method, and the like. Among these, the melt extrusion molding method is preferable from the viewpoint of obtaining a biaxial optical anisotropic plate excellent in mechanical strength and surface accuracy.

  The biaxial optical anisotropic plate used in the liquid crystal display device of the second embodiment is preferably obtained by stretching a film made of the thermoplastic resin. As a method of stretching the film made of the thermoplastic resin, a uniaxial stretching method such as a method of stretching uniaxially in a transverse direction using a tenter; a gap between fixed clips is opened, and the guide rail spreads simultaneously with stretching in the longitudinal direction. Simultaneous biaxial stretching method that stretches in the transverse direction depending on the angle, or sequential stretching that stretches in the longitudinal direction using the difference in peripheral speed between rolls and then grips both ends of the clip and stretches in the transverse direction using a tenter. Biaxial stretching method such as axial stretching method; Tenter stretching machine that can add feed force or pulling force or pulling force at different speeds in the horizontal or vertical direction; Or, using a tenter stretching machine that can add a pulling force or a pulling force so that the moving distance is the same and the stretching angle θ can be fixed, or the moving distance is different. How to oblique stretching: and the like.

  The conditions for stretching the film made of the thermoplastic resin are not particularly limited, but the stretching temperature is usually in the range of Tg to Tg + 20 ° C., assuming that the glass transition temperature of the thermoplastic resin is Tg, Adjustment is usually made in the range of 1.1 to 6.0 times to obtain desired optical characteristics.

In the second embodiment, when the main refractive index in the in-plane direction of the biaxial optical anisotropic plate is _nx , _ny , and the main refractive index in the thickness direction is _nz , the biaxial optical all anisotropic plate satisfies the _{n x> n y> n z} . If the biaxial optical anisotropic plate does not have such characteristics, the contrast viewing angle is deteriorated, or the liquid crystal display device of the second embodiment is observed obliquely from the hue of the color image when observed from the front. There is a possibility that the color tone of the color image may differ greatly.

In the second embodiment, the retardation in the in-plane direction of the biaxial optical anisotropic plate when light having a wavelength of 450 nm and a wavelength of 550 nm is incident at an incident angle of 0 degrees is Re ₄₅₀ and Re ₅₅₀ . In this case, it is preferable that all of the biaxial optical anisotropic plates satisfy a relationship of 0.9 ≦ Re ₄₅₀ / Re ₅₅₀ ≦ 1.05. When the biaxial optical anisotropic plate has such characteristics, the display image of the liquid crystal display device of the present invention can have the same color balance in front and oblique observation.
Retardations Re ₄₅₀ and Re ₅₅₀ are high-speed spectroscopic ellipsometers [J. A. Woolam Co., Ltd., M-2000U], and measured with light having a wavelength of 450 nm and a wavelength of 550 nm being incident.

  In the liquid crystal display device of the second embodiment, as a form including one biaxial optical anisotropic plate, (I) one biaxial optical anisotropic plate is provided between the output-side polarizer and the liquid crystal cell. There are two forms: a form, and (II) a form in which one biaxial optical anisotropic plate is provided between the incident-side polarizer and the liquid crystal cell.

  In the embodiment (I) or (II), the slow axis in the plane of the biaxial optical anisotropic plate and the polarized light transmission of the polarizer disposed in the vicinity of the biaxial optical anisotropic plate The axis is preferably in a substantially parallel positional relationship. In the present specification, “substantially parallel” means that the angle formed by the two axes is 0 to 3 degrees, more preferably 0 to 1 degree.

  In the liquid crystal display device according to the second embodiment, there are the following three types (III) to (V) as the two biaxial optical anisotropic plates. (III) One biaxial optical anisotropic plate is provided between the exit side polarizer and the liquid crystal cell, and one biaxial optical anisotropic plate is provided between the entrance side polarizer and the liquid crystal cell of the liquid crystal display device. A form with sheets. (VI) A mode in which two biaxial optical anisotropic plates are provided between the exit-side polarizer and the liquid crystal cell. (V) A mode in which two biaxial optical anisotropic plates are provided between the incident-side polarizer and the liquid crystal cell. Among these, the form of (III) is preferable.

  In the form (III), the slow axis in the plane of the biaxial optical anisotropic plate disposed between the exit side polarizer and the liquid crystal cell, and the polarization transmission axis of the exit side polarizer are: The slow axis in the plane of the biaxial optical anisotropic plate disposed between the incident side polarizer and the liquid crystal cell and the polarization transmission axis of the incident side polarizer are in a substantially parallel positional relationship. It is preferable that they are in a substantially parallel positional relationship.

In the liquid crystal display device according to the second embodiment, the protective film on the side near the liquid crystal cell of the output side polarizing plate, which is arranged between the input side polarizer and the output side polarizer, and the vertical alignment mode in the state where no voltage is applied. When the liquid crystal cell, the protective film on the side near the liquid crystal cell of the incident-side polarizing plate, and all the biaxial optical anisotropic plates are temporarily formed into a laminate or multilayer, the laminate or multilayer has a wavelength of 550 nm. The retardation R ₀ when the incident light is incident at an incident angle of 0 ° and the retardation R ₄₀ when the light having a wavelength of 550 nm is incident at the incident angle of 40 ° are | R ₄₀ −R ₀ | ≦ 35 nm. Satisfy the relationship.

In the present invention, the retardation R ₀ is a retardation when light having a wavelength of 550 nm is incident from the position of α (normal direction of the optical laminated plate surface) as shown in FIG. As shown in FIG. 10, R ₄₀ is a direction inclined by 45 degrees in the plane from the direction of the slow axis (x axis) in the plane of the biaxial optical anisotropic plate (that is, the fast axis (in-plane fast axis ( The retardation is obtained when light having a wavelength of 550 nm is incident from a position of β which is a direction inclined by 45 degrees from the direction of the y-axis) and a direction inclined by 40 degrees from the normal line.
Retardations R ₀ and R ₄₀ are high-speed spectroscopic ellipsometers [J. A. Woolam, M-2000U] is a value measured by making light having a wavelength of 550 nm incident from the positions of α and β.

  In the liquid crystal display device of the second embodiment, the optical filter of the present invention is further provided between the incident side polarizer and the light source. In the optical filter of the present invention, the light emitted from the light source is transmitted with a light transmittance that satisfies the relationship of the formula [1].

  In the liquid crystal display device of the second embodiment, it is preferable that the incident side polarizing plate and the optical filter are integrated. By being integrated, there is no space between the incident-side polarizing plate and the optical filter. The method of uniting is not particularly limited. For example, a method of bonding them using an adhesive or a pressure-sensitive adhesive, a method of bringing plasma into contact with these surfaces, and then crimping them are included. The adhesive or pressure-sensitive adhesive is preferably transparent to visible light, and preferably does not generate an unnecessary phase difference. When the incident-side polarizing plate and the optical filter are integrated, the optical filter also functions as a protective film for the incident-side polarizer, so the protective film on the light source side of the incident-side polarizing plate is omitted. Can do.

  In the liquid crystal display device according to the second embodiment, the polarization transmission axis of the output-side polarizer and the polarization transmission axis of the incident-side polarizer are usually arranged substantially at right angles. In this specification, the term “substantially perpendicular” means that the angle formed by the two axes is 87 to 90 degrees, more preferably 89 to 90 degrees.

(3rd embodiment of a liquid crystal display device)
The liquid crystal display device according to the third embodiment of the present invention includes an output side polarizing plate, an in-plane switching mode liquid crystal cell, an incident side polarizing plate, and a light source in this order.
The exit side polarizing plate includes an exit side polarizer and protective films laminated on both sides of the exit side polarizer. The incident-side polarizing plate includes an incident-side polarizer and a protective film laminated on both surfaces of the incident-side polarizer.

In the liquid crystal display device of the third embodiment further between the during and / or entrance side polarizer and the liquid crystal cell and the outgoing side polarizing element and the liquid crystal cell, the relationship of n _x> n _y and n _z> n _y (However, n _x is the in-plane slow axis direction of the refractive index, n _y is a refractive index in the direction perpendicular in the plane to the slow axis, n _z is a refractive index in the thickness direction) biaxial optically anisotropic satisfying One or two square plates are provided.

  As a mode of disposing the biaxial optical anisotropic plate, a mode in which one sheet is disposed only between the output side polarizer and the liquid crystal cell, and a mode in which one sheet is disposed only between the incident side polarizer and the liquid crystal cell. A mode in which one sheet is disposed between the output side polarizer and the liquid crystal cell, and a mode in which two sheets are disposed only between the output side polarizer and the liquid crystal cell. A mode in which two sheets are disposed only between the polarizer and the liquid crystal cell, a mode in which two sheets are disposed between the output side polarizer and the liquid crystal cell, and between the incident side polarizer and the liquid crystal cell, and the output side polarizer. A mode in which one sheet is disposed between the liquid crystal cell and two sheets are disposed between the incident side polarizer and the liquid crystal cell, and two sheets are disposed between the output side polarizer and the liquid crystal cell. A mode in which one sheet is arranged between the liquid crystal cells is included.

  The biaxial optical anisotropic plate used in the third embodiment is a transparent film. The transparent film can be used without particular limitation as long as the total light transmittance is 80% or more.

  There is no restriction | limiting in particular as a material which forms a biaxial optically anisotropic plate, Materials, such as resin and a liquid crystal, are mentioned. The biaxial optical anisotropic plate used in the third embodiment includes (i) a resin having a negative intrinsic birefringence value, (ii) a discotic liquid crystal, (iii) a lyotropic liquid crystal, or (iv) a photoisomerized substance. It is preferable to consist of a layer containing any of the above materials.

(I) Layer containing a resin having a negative intrinsic birefringence value A resin having a negative intrinsic birefringence value means that when light is incident on a layer in which molecules are oriented in a uniaxial order, The refractive index is smaller than the refractive index of light in the direction orthogonal to the orientation direction.

Examples of the resin having a negative intrinsic birefringence value include vinyl aromatic polymer resins such as polystyrene, acrylic resins such as polyacrylonitrile and polymethyl methacrylate, polycarbonate resins such as polycarbonate, and cellulose acetate resins such as triacetyl cellulose. And a multi-component copolymer of monomers as raw materials for these resins.
These resins having a negative intrinsic birefringence value can be used alone or in combination of two or more. Among these, vinyl aromatic polymer resins and acrylic resins can be suitably used, and vinyl aromatic polymer resins are particularly preferred because of their high birefringence.

  Examples of the vinyl aromatic polymer resin include styrene, α-methylstyrene, o-methylstyrene, p-methylstyrene, p-chlorostyrene, p-nitrostyrene, p-aminostyrene, p-carboxystyrene, and Homopolymers of vinyl aromatic monomers such as p-phenylstyrene, and these vinyl aromatic monomers and ethylene, propylene, butadiene, isoprene, (meth) acrylonitrile, α-chloroacrylonitrile, (meth) acrylic Examples thereof include copolymers with other monomers such as methyl acid, ethyl (meth) acrylate, (meth) acrylic acid, maleic anhydride, and vinyl acetate. Of these, a homopolymer of polystyrene or a copolymer of styrene and maleic anhydride can be suitably used.

  If necessary, the resin having a negative intrinsic birefringence value may include an antioxidant, a heat stabilizer, a light stabilizer, an ultraviolet absorber, an antistatic agent, a dispersant, a chlorine scavenger, a flame retardant, and a crystallization. Nucleating agent, antiblocking agent, antifogging agent, release agent, pigment, organic or inorganic filler, neutralizing agent, lubricant, decomposition agent, metal deactivator, antifouling agent, antibacterial agent and other resins, And well-known additives, such as a thermoplastic elastomer, may contain in the range which does not impair the effect of invention.

  The layer containing a resin having a negative intrinsic birefringence value may contain a resin having a positive intrinsic birefringence value. Further, it is preferably a laminate in which a layer made of a resin having a positive intrinsic birefringence value is laminated on at least one surface of a layer made of a resin having a negative intrinsic birefringence value, and the intrinsic birefringence value is negative. Particularly preferred is a laminate in which layers made of a resin having a positive intrinsic birefringence value are laminated on both surfaces of a layer made of a resin.

  A laminate in which a layer made of a resin having a negative intrinsic birefringence value and a layer made of a resin having a positive intrinsic birefringence value are laminated on at least one side of a layer made of a resin having a negative intrinsic birefringence value. There is no restriction | limiting in particular as a method to manufacture this, For example, conventionally well-known methods, such as a solution casting method, an injection molding method, and a melt extrusion method, are mentioned.

  The layer made of a resin having a negative intrinsic birefringence value is preferably a layer in which a layer made of a resin having a negative intrinsic birefringence value is oriented. Furthermore, a resin having a negative intrinsic birefringence value from the viewpoint of excellent processing performance, the ability to form a biaxial optical anisotropic plate efficiently and easily, and the ability to have a stable and homogeneous phase difference over a long period of time. Preferably, a layered body in which a layer made of a resin having a positive intrinsic birefringence value is laminated on at least one side of a layer oriented by the layer, and a layer made of a resin having a negative intrinsic birefringence value is oriented. A laminate in which layers made of a resin having a positive intrinsic birefringence value are laminated on both surfaces of the layer is particularly preferable. In this case, the layer made of a resin having a positive intrinsic birefringence value may be substantially non-oriented from the viewpoint of efficiently using the phase difference of the layer made of a resin having a negative intrinsic birefringence value. preferable.

  Resin having a positive intrinsic birefringence value on at least one side of the layer in which the layer made of the resin having a negative intrinsic birefringence value is oriented and the layer having the orientation made of the resin having a negative intrinsic birefringence value A method for producing a laminate in which layers composed of the above layers are produced is not particularly limited, but the intrinsic birefringence value is negative from the viewpoint of uniformly and efficiently controlling the refractive index in the thickness direction of the biaxial optical anisotropic body. A method of stretching a laminate in which a layer made of a resin having a positive intrinsic birefringence value is laminated on at least one side of a layer made of a resin or a layer made of a resin having a negative intrinsic birefringence value is preferable. In this case, when the glass transition temperature of a resin having a negative intrinsic birefringence value is TgA (° C.) and the glass transition temperature of a resin having a negative intrinsic birefringence value is TgB (° C.), TgA (° C.)> By satisfying the relationship of TgB (° C.) + 20 (° C.), a substance made of a resin having a positive intrinsic birefringence value is provided on at least one side of a layer in which a layer made of a resin having a negative intrinsic birefringence value is oriented. In addition, it is possible to efficiently obtain a laminate in which non-oriented layers are laminated.

  Further, from the viewpoint of controlling the in-plane refractive index of the biaxial optical anisotropic body, a method of further laminating another stretched film on the layer made of the resin having a negative stretched intrinsic birefringence value is also preferable. Furthermore, the layer made of a resin having a negative intrinsic birefringence value has a structure in which a layer made of a resin having a positive intrinsic birefringence value is laminated on both sides thereof via an adhesive resin layer. You can also.

As described above, the intrinsic birefringence value is positive by stretching a layer made of a resin having a negative intrinsic birefringence value, or on at least one surface of a layer made of a resin having a negative intrinsic birefringence value. By stretching a laminate in which layers made of a resin are stretched, the refractive index in the direction perpendicular to the stretching direction of these layers is increased, the refractive index in the stretching direction is decreased, and _nz > _ny , which will be described later, and the n _x> satisfy the relation of n _y biaxial optical anisotropic plate can be efficiently preferably formed.

(Ii) Layer including discotic liquid crystal Examples of discotic liquid crystal include C.I. Desradet et al., Mol. Crysr. Liq. Cryst., Vol. 71, page 111 (1981); Kohne et al., Angew. Chem. 96, p. 70 (1984); M.M. Lehn et al. Chem. Commun., 1794 (1985), J. Am. Zhang et al., J. Am. Chem. Soc. 116, 2655 (1994) and the like, such as azacrown and phenylacetylene macrocycles. A discotic liquid crystal generally has a structure in which a linear alkyl group, an alkoxy group, a substituted benzoyloxy group, and the like are radially substituted as a linear chain with these as the molecular center.

  Furthermore, examples of the discotic liquid crystal include a compound represented by the chemical formula [1] and a compound represented by the chemical formula [2].

There is no particular limitation on the method for forming the layer containing the discotic liquid crystal, but a method of laminating the discotic liquid crystal on the base material is preferable, and the discotic liquid crystal is oriented so as to be substantially perpendicular to the base material surface. The method is particularly preferred. By oriented substantially perpendicular to the substrate surface discotic liquid, forming n _z> n _y described later, and satisfy the relationship of n _x> n _y a biaxial optical anisotropic plate efficiently can do. Examples of the substrate on which the discotic liquid crystal is laminated include a plate-like material made of glass, synthetic resin, or the like. By laminating the discotic liquid crystal on the surface of the polarizer used in the present invention, the optical filter of the present invention, etc., the liquid crystal display device can be reduced in weight and thickness, and the production efficiency can be increased. “Aligning substantially perpendicularly” means that the plane of the liquid crystal molecules is aligned in the range of 60 to 90 degrees with respect to the substrate surface.

  As a method for aligning the discotic liquid crystal substantially vertically, for example, a vertical alignment film in which a coating liquid containing a discotic liquid crystal or a discotic liquid crystal and other additives, a polymerization initiator, etc. is applied on a substrate is used. Examples thereof include a method of coating and fixing on the substrate, a method of coating the coating solution on the vertical alignment film and fixing it, and then peeling off from the vertical alignment film and laminating on the substrate.

  A vertical alignment film is a film having a low surface energy that can vertically align liquid crystal molecules, and is usually composed of a polymer. As the polymer constituting the vertical alignment film, a polymer in which a fluorine atom or a hydrocarbon group having 10 or more carbon atoms is introduced into the side chain can be suitably used. As the hydrocarbon group, either an aliphatic group or an aromatic group can be used. The main chain of the polymer preferably has a polyimide structure or a polyvinyl alcohol structure. The degree of polymerization of the polymer is preferably 200 to 5,000, and more preferably 300 to 3,000. The molecular weight of the polymer is preferably 9,000 to 200,000, and more preferably 13,000 to 130,000.

  In the present invention, in the formation of the vertical alignment film, it is preferable to perform a rubbing process in which the surface of the film containing the polymer is rubbed several times in a certain direction with cloth, paper or the like.

  For the preparation of the coating solution, water or an organic solvent can be used. Examples of the organic solvent include amides such as N, N-dimethylformamide; sulfoxides such as dimethyl sulfoxide; heterocyclic compounds such as pyridine; Hydrocarbons such as hexane; halides such as chloroform and methylene chloride; esters such as methyl acetate and butyl acetate; ketones such as acetone and methyl ethyl ketone; ethers such as tetrahydrofuran and 1,2-dimethoxyethane; Can be mentioned. There is no restriction | limiting in particular in the coating method of a coating liquid, For example, an extrusion coating method, a direct gravure coating method, a reverse gravure coating method, a die coating method etc. can be mentioned.

  The vertically aligned discotic liquid crystal is preferably fixed while maintaining the alignment state. Examples of the immobilization method include a thermal polymerization reaction method using a thermal polymerization initiator and a photopolymerization reaction method using a photopolymerization initiator. Among these, the photopolymerization reaction method is particularly preferable. Examples of the photopolymerization initiator include α-carbonyl compounds, acyloin ethers, α-hydrocarbon substituted aromatic acyloin compounds, polynuclear quinone compounds, combinations of triarylimidazole dimers and p-aminophenyl ketones, acridine and phenazine compounds. And oxadiazole compounds.

  After the liquid crystal molecules are aligned vertically using the vertical alignment film, the liquid crystal molecules are fixed in the aligned state to form an optical anisotropic layer, and only the optical anisotropic layer is transferred onto the transparent polymer film. be able to. The liquid crystal molecules fixed in the vertical alignment state can maintain the alignment state without the vertical alignment film. The direction in which the in-plane refractive index of the layer containing the discotic liquid crystal becomes maximum due to the orientation of the discotic liquid crystal is a direction substantially parallel to the disc surface of the discotic liquid crystal molecules.

(Iii) Layer containing lyotropic liquid crystal The lyotropic liquid crystal is a molecule exhibiting liquid crystallinity when dissolved in a specific solvent in a specific concentration range. The lyotropic liquid crystal includes, for example, a polymer lyotropic liquid crystal molecule in which a main chain such as a cellulose derivative, a polypeptide, and a nucleic acid has a rod-like skeleton dissolved therein; a concentrated aqueous solution of an amphiphilic low-molecular compound. And amphiphilic lyotropic liquid crystal molecules; and chromonic liquid crystal molecules comprising a solution of a low molecular compound having an aromatic ring imparted with water solubility.

In the present invention, the lyotropic liquid crystal is preferably aligned in a specific direction by shearing, and the liquid crystal molecular plane is particularly preferably aligned substantially perpendicular to the substrate surface. Here, “substantially perpendicularly aligned” means that the plane of the liquid crystal molecules is aligned in the range of 60 to 90 degrees with respect to the substrate surface. By aligning the liquid crystal molecular plane substantially perpendicular to the substrate surface, the refractive index in the thickness direction of the biaxial optical anisotropic plate is controlled, and _nz > _ny and _nx > _ny A biaxial optical anisotropic plate that satisfies the above relationship can be formed efficiently.

  Examples of the base material on which the lyotropic liquid crystal is laminated include a plate-like material made of glass, synthetic resin, or the like. By laminating the lyotropic liquid crystal on the surface of the polarizer used in the present invention, the optical filter of the present invention, etc., the liquid crystal display device can be reduced in weight and thickness, and the production efficiency can be increased.

  The lyotropic liquid crystal preferably has substantially no light absorption in the visible light region. Examples of such lyotropic liquid crystals include compounds represented by chemical formula [3] and chemical formula [4].

  The method for forming the layer containing the lyotropic liquid crystal is not particularly limited, but a method of aligning the lyotropic liquid crystal substantially perpendicularly to the substrate surface by shearing is preferable. By aligning the lyotropic liquid crystal perpendicularly to the substrate surface, the refractive index in the thickness direction of the biaxial optical anisotropic plate can be efficiently controlled. Examples of the method for vertically aligning the lyotropic liquid crystal include a method in which a lyotropic liquid crystal solution or a solution containing a lyotropic liquid crystal and an additive is applied on a substrate and fixed. In this alignment treatment, an alignment film is used because it has excellent manufacturing efficiency, can achieve weight reduction and thinning, prevents damage to the base material, and can be applied with a uniform thickness. Preferably not.

  As a solvent used for preparing the solution of the lyotropic liquid crystal, water or an organic solvent can be used. Examples of the organic solvent include amides such as N, N-dimethylformamide; sulfoxides such as dimethyl sulfoxide; heterocyclic compounds such as pyridine; hydrocarbons such as benzene and hexane; halides such as chloroform and methylene chloride. Esters such as methyl acetate and butyl acetate; ketones such as acetone and methyl ethyl ketone; and ethers such as tetrahydrofuran and 1,2-dimethoxyethane; The concentration of the lyotropic liquid crystal solution is not particularly limited as long as the solution exhibits liquid crystallinity, but is preferably 0.0001 to 100 parts by weight of lyotropic liquid crystal with respect to 100 parts by weight of the solvent. More preferred are parts by weight. There is no particular limitation on the method for applying the solution of the lyotropic liquid crystal, and examples thereof include an extrusion coating method, a direct gravure coating method, a reverse gravure coating method, and a die coating method.

  The lyotropic liquid crystal aligned by shearing is preferably fixed while maintaining the alignment state. Examples of the immobilization method include a solvent removal method by drying, a thermal polymerization reaction method using a thermal polymerization initiator, and a photopolymerization reaction method using a photopolymerization initiator. The direction in which the in-plane refractive index of the layer containing the lyotropic liquid crystal becomes maximum due to the orientation of the lyotropic liquid crystal is a direction substantially parallel to or substantially perpendicular to the molecular plane of the lyotropic liquid crystal.

(Iv) Layer containing a photoisomerization substance A photoisomerization substance is a substance that causes stereoisomerization or structural isomerization by light, and among them, a substance that causes reverse isomerization by light of different wavelengths or heat is preferably used. be able to. Such substances include photochromic compounds with structural isomerization and color change in the visible range. Specific examples thereof include azobenzene compounds, benzaldoxime compounds, azomethine compounds, stilbene compounds, spiropyrans. Examples thereof include spirooxazine compounds, fulgide compounds, diarylethene compounds, cinnamic acid compounds, retinal compounds, and hemithioindigo compounds.

  As the photoisomerization substance, either a low molecular compound or a polymer can be used. In the case of a polymer, the photoisomerization group may be present in either the main chain or the side chain. The polymer may be either a homopolymer or a copolymer. In order to adjust the photoisomerization ability, glass transition temperature, and the like of the copolymer, the comonomer and copolymerization ratio can be appropriately selected. In the present invention, the photoisomerizable substance having a functional group capable of photoisomerization is simultaneously a liquid crystal compound, that is, a compound having a functional group capable of photoisomerizing the liquid crystal compound.

  Examples of the photoisomerization substance include an acrylate ester polymer represented by the chemical formula [5].

There is no particular limitation on the method for forming the layer containing the photoisomerized substance. For example, a solution containing the photoisomerized substance is applied on the substrate to form a film-like surface, and after passing through the drying process, the linearly polarized light is irradiated. And the like. The linearly polarized light is preferably irradiated from a direction perpendicular to the film surface.
Irradiation with linearly polarized light can be performed from the time when the coating layer is substantially dried. “Substantially dry” can be determined by using a residual solvent in the coating layer of 30% by weight or less. The temperature for irradiating the linearly polarized light can be appropriately selected according to the amount of the residual solvent, but when the glass transition temperature of the photoisomerized material is Tg (° C), Tg-50 (° C) to Tg + 30 (° C ) Is preferable.

The linearly polarized light source is not particularly limited, and examples thereof include a mercury lamp and a halogen lamp. By irradiating with linearly polarized light, the direction in which the in-plane refractive index of the layer containing the photoisomerizable substance becomes maximum becomes a direction substantially orthogonal to the polarization axis of the irradiated light. By this method, n _z> n _y, and n _x> satisfy the relation of n _y biaxial optical anisotropic plate can be efficiently formed.

  Examples of the substrate on which the solution containing the photoisomerization substance is applied include a plate-like material made of glass, synthetic resin, or the like. By laminating the photoisomerized substance on the surface of the polarizer used in the present invention, the optical filter of the present invention, etc., the liquid crystal display device can be reduced in weight and thickness, and the production efficiency can be increased.

  There is no restriction | limiting in particular in the solvent used for preparation of the solution containing a photoisomerization substance, For example, methanol, a methylene chloride, acetone, methyl ethyl ketone, etc. can be mentioned. There is no restriction | limiting in particular in the density | concentration of a solution, Although it can select suitably so that it may become a suitable viscosity for application | coating, Usually, it is 1-100 weight part of photoisomerization substances with respect to 100 weight part of solvents. Is preferred. There is no restriction | limiting in particular in the application | coating method of a solution, For example, it can apply | coat using a bar coater, a roll coater, etc.

In the third embodiment, when the main refractive index in the in-plane direction of the biaxial optical anisotropic plate is _nx , _ny , and the main refractive index in the thickness direction is _nz , the biaxial optical all anisotropic plate, n _z> n _y, and satisfies the n _x> n _y. When the biaxial optical anisotropic plate has such characteristics, the contrast viewing angle is good, and the display image of the liquid crystal display device of the present invention has the same color balance in the front and oblique observations. can do.

In the liquid crystal display device of the third embodiment, the retardation in the in-plane direction of the biaxial optical anisotropic plate when light having a wavelength of 450 nm and a wavelength of 550 nm is incident at an incident angle of 0 degree is represented by Re ₄₅₀ , and When Re ₅₅₀ is set, it is preferable that all the biaxial optical anisotropic plates satisfy the relationship of 0.9 ≦ Re ₄₅₀ / Re ₅₅₀ ≦ 1.1. When the biaxial optical anisotropic plate has such characteristics, the display image of the liquid crystal display device according to the third embodiment can have the same color balance in front and oblique observations. .
Retardations Re ₄₅₀ and Re ₅₅₀ are high-speed spectroscopic ellipsometers [J. A. Woolam Co., Ltd., M-2000U], and measured with light having a wavelength of 450 nm and a wavelength of 550 nm being incident.

  In the liquid crystal display device of the third embodiment, as a form including one biaxial optical anisotropic plate, (I) one biaxial optical anisotropic plate is provided between the output-side polarizer and the liquid crystal cell. There are two types: a configuration and (II) a configuration in which one biaxial optical anisotropic plate is provided between the incident side polarizer and the liquid crystal cell.

  In the embodiment (I) or (II), the slow axis in the plane of the biaxial optical anisotropic plate and the polarization absorption of the polarizer disposed in the vicinity of the biaxial optical anisotropic plate The axis is preferably in a substantially parallel or substantially perpendicular positional relationship. In the present specification, “substantially parallel” means that the angle formed by the two axes is within 3 degrees, more preferably within 1 degree. A substantially right angle means that the angle formed by the two axes is 87 to 93 degrees, more preferably 89 to 91 degrees.

  In the liquid crystal display device of the present invention, the following three types (III) to (V) are provided as the two biaxial optical anisotropic plates. (III) One biaxial optical anisotropic plate is provided between the exit side polarizer and the liquid crystal cell, and one biaxial optical anisotropic plate is provided between the entrance side polarizer and the liquid crystal cell of the liquid crystal display device. A form with sheets. (VI) A mode in which two biaxial optical anisotropic plates are provided between the exit-side polarizer and the liquid crystal cell. (V) A mode in which two biaxial optical anisotropic plates are provided between the incident-side polarizer and the liquid crystal cell. Among these, the form of (III) is preferable.

  In the form (III), the slow axis in the plane of the biaxial optical anisotropic plate disposed between the exit side polarizer and the liquid crystal cell, and the polarization absorption axis of the exit side polarizer are: The slow axis in the plane of the biaxial optical anisotropic plate disposed between the incident side polarizer and the liquid crystal cell and the polarization absorption axis of the incident side polarizer are in a substantially parallel positional relationship. It is preferable that they are in a substantially parallel positional relationship.

  In the liquid crystal display device of the third embodiment, the polarization absorption axis of the exit-side polarizer or the polarization absorption axis of the entrance-side polarizer and the slow axis of the liquid crystal cell in the state where no voltage is applied are substantially parallel or substantially perpendicular. Preferably there is.

In the liquid crystal display device of the third embodiment, the protective film on the side near the liquid crystal cell of the output side polarizing plate, which is disposed between the input side polarizer and the output side polarizer, in-plane switching mode in the state where no voltage is applied When the liquid crystal cell, the protective film on the side near the liquid crystal cell of the incident-side polarizing plate, and all the biaxial optical anisotropic plates are temporarily formed into a laminate or multilayer, the laminate or multilayer has a wavelength of 550 nm. The retardation R ₀ when the incident light is incident at an incident angle of 0 ° and the retardation R ₄₀ when the light having a wavelength of 550 nm is incident at the incident angle of 40 ° are | R ₄₀ −R ₀ | ≦ 35 nm. Satisfy the relationship.

  In the liquid crystal display device of the third embodiment, the optical filter is further provided between the incident side polarizer and the light source. In the optical filter of the present invention, the light emitted from the light source is transmitted with a light transmittance that satisfies the relationship of the formula [1].

  In the liquid crystal display device of the third embodiment, it is preferable that the incident side polarizing plate and the optical filter are integrated. By being integrated, there is no space between the incident-side polarizing plate and the optical filter. The method of uniting is not particularly limited. For example, a method of bonding them using an adhesive or a pressure-sensitive adhesive, a method of bringing plasma into contact with these surfaces, and then crimping them are included. The adhesive or pressure-sensitive adhesive is preferably transparent to visible light, and preferably does not generate an unnecessary phase difference. When the incident-side polarizing plate and the optical filter are integrated, the optical filter also functions as a protective film for the incident-side polarizer, so the protective film on the light source side of the incident-side polarizing plate is omitted. can do.

(Fourth embodiment of liquid crystal display device)
The liquid crystal display device of the fourth embodiment of the present invention includes an output side polarizing plate, an in-plane switching mode liquid crystal cell, an incident side polarizing plate, and a light source in this order.
The exit-side polarizing plate includes an exit-side polarizer and a protective film laminated on both surfaces of the exit-side polarizer. The incident side polarizing plate includes an incident side polarizer and a protective film laminated on both surfaces of the incident side polarizer.

In the liquid crystal display device of the fourth embodiment, In addition, or between the incident-side polarizer and the liquid crystal cell and the outgoing side polarizing element and the liquid crystal cell, the one that satisfies the relationship of n _z ≧ n _x> n _y The first optical anisotropic plate and a single second optical anisotropic plate satisfying the relationship of n _x > _ny ≧ _nz are provided in a multilayer or stacked manner.
first optical anisotropic plate satisfying the relation of n _z ≧ n _x> n _y is biaxial optical satisfying liquid crystal display device relationship n _x> n _y and n _z> n _y used in the third embodiment You can select from anisotropic plates.
n _x> n _y ≧ n second optical anisotropic plate satisfying the relation _z is the same as the biaxial optical anisotropic plate used in the liquid crystal display device of the second embodiment _{(n x> n y> n} z it may be used as) that satisfies the relationship may be used satisfy the relation of _{n x> n y = n z} .
and n _z ≧ n _x> slow axis of the first optically anisotropic plate satisfying the relation of n _y, it is preferable that the polarization absorption axis of the incident-side polarizer is arranged substantially at a right angle.
n _x> and n _y ≧ n second optical slow axis of the anisotropic plate satisfying the relation of _z, it is preferable that the polarization absorption axis of the incident-side polarizer is arranged substantially at a right angle.

Further, in the liquid crystal display device according to the fourth embodiment, the protective film on the side close to the liquid crystal cell of the output-side polarizing plate disposed between the input-side polarizer and the output-side polarizer, the in-plane in which no voltage is applied When the switching mode liquid crystal cell, the protective film on the side of the incident side polarizing plate close to the liquid crystal cell, and all the optical anisotropic plates are laminated or multilayered, the laminated or multilayered light has a wavelength of 550 nm. the retardation R ₀ when is incident at an incident angle of 0 degrees, and retardation R ₄₀ when light having a wavelength 550nm is incident at an incident angle of 40 degrees, | R ₄₀ -R ₀ | ≦ 35 nm of the relationship Meet.

  The liquid crystal display device according to the fourth embodiment further includes the optical filter of the present invention between the incident-side polarizer and the light source. In the optical filter of the present invention, the light emitted from the light source is transmitted with a light transmittance that satisfies the relationship of the formula [1].

  In the liquid crystal display device of the fourth embodiment, it is preferable that the incident side polarizing plate and the optical filter are integrated. By being integrated, there is no space between the incident-side polarizing plate and the optical filter. The method of uniting is not particularly limited. For example, a method of bonding them using an adhesive or a pressure-sensitive adhesive, a method of bringing plasma into contact with these surfaces, and then crimping them are included. The adhesive or pressure-sensitive adhesive is preferably transparent to visible light, and preferably does not generate an unnecessary phase difference. When the incident-side polarizing plate and the optical filter are integrated, the optical filter also functions as a protective film for the incident-side polarizer, so the protective film on the light source side of the incident-side polarizing plate is omitted. can do.

(Fifth embodiment of liquid crystal display device)
A liquid crystal display device according to a fifth embodiment of the present invention includes a liquid crystal panel including the polarizing plate of the present invention. In the liquid crystal display device of the fifth embodiment, the polarizing plate of the present invention is disposed between the light source and the liquid crystal cell, and the light emitted from the light source satisfies the relationship of the formula [2] in the polarizing plate of the present invention. Be transparent at rate.

(Sixth embodiment of liquid crystal display device)
The liquid crystal display device of the sixth embodiment of the present invention includes an output side polarizing plate, a vertical alignment mode liquid crystal cell, an incident side polarizing plate, and a light source in this order.
The exit-side polarizing plate includes an exit-side polarizer and a protective film laminated on both surfaces of the exit-side polarizer. The incident side polarizing plate is composed of the polarizing plate of the present invention.

In the liquid crystal display device of the sixth embodiment, further, between and / or between the incident side polarizer and the liquid crystal cell and the outgoing side polarizing element and the liquid crystal cell, the relationship of _{n x> n y> n z} ( where n _x is the in-plane slow axis direction of the refractive index, n _y is the refractive index in the direction orthogonal in the plane to the slow axis, n _z is a biaxial optical anisotropic plate satisfying the refractive index) in the thickness direction One or two are provided.

  As a mode of disposing the biaxial optical anisotropic plate, a mode in which one sheet is disposed only between the output side polarizer and the liquid crystal cell, and a mode in which one sheet is disposed only between the incident side polarizer and the liquid crystal cell. A mode in which one sheet is disposed between the output side polarizer and the liquid crystal cell, and a mode in which two sheets are disposed only between the output side polarizer and the liquid crystal cell. A mode in which two sheets are disposed only between the polarizer and the liquid crystal cell, a mode in which two sheets are disposed between the output side polarizer and the liquid crystal cell, and between the incident side polarizer and the liquid crystal cell, and the output side polarizer. A mode in which one sheet is disposed between the liquid crystal cell and two sheets are disposed between the incident side polarizer and the liquid crystal cell, and two sheets are disposed between the output side polarizer and the liquid crystal cell. A mode in which one sheet is arranged between the liquid crystal cells is included.

  The biaxial optical anisotropic plate used in the sixth embodiment is the same as that exemplified as the biaxial optical anisotropic plate used in the second embodiment. The arrangement direction of the biaxial optical anisotropic plate can be the same as that shown in the second embodiment.

In the sixth embodiment, Re ₄₅₀ and Re ₅₅₀ are retardations in the in-plane direction of the biaxial optical anisotropic plate when light having a wavelength of 450 nm and a wavelength of 550 nm is incident at an incident angle of 0 degree. In this case, it is preferable that all of the biaxial optical anisotropic plates satisfy a relationship of 0.9 ≦ Re ₄₅₀ / Re ₅₅₀ ≦ 1.05. When the biaxial optical anisotropic plate has such characteristics, the display image of the liquid crystal display device of the sixth embodiment can have the same color balance in front and oblique observations. .
Retardations Re ₄₅₀ and Re ₅₅₀ are high-speed spectroscopic ellipsometers [J. A. Woolam Co., Ltd., M-2000U], and measured with light having a wavelength of 450 nm and a wavelength of 550 nm being incident.

In the liquid crystal display device of the sixth embodiment, the protective film on the side near the liquid crystal cell of the exit side polarizing plate, which is arranged between the entrance side polarizer and the exit side polarizer, and the vertical alignment mode in the absence of voltage application When the liquid crystal cell, the protective film on the side near the liquid crystal cell of the incident-side polarizing plate, and all the biaxial optical anisotropic plates are temporarily formed into a laminate or multilayer, the laminate or multilayer has a wavelength of 550 nm. The retardation R ₀ when the incident light is incident at an incident angle of 0 ° and the retardation R ₄₀ when the light having a wavelength of 550 nm is incident at the incident angle of 40 ° are | R ₄₀ −R ₀ | ≦ 35 nm. Satisfy the relationship.

  In the liquid crystal display device of the sixth embodiment, the light emitted from the light source is transmitted with the light transmittance satisfying the relationship of the formula [2] in the incident side polarizing plate made of the polarizing plate of the present invention. .

(Seventh embodiment of liquid crystal display device)
The liquid crystal display device according to the seventh embodiment of the present invention includes an output side polarizing plate, an in-plane switching mode liquid crystal cell, an incident side polarizing plate, and a light source in this order.
The exit side polarizing plate includes an exit side polarizer and protective films laminated on both sides of the exit side polarizer. The incident side polarizing plate comprises the polarizing plate of the present invention.

In the liquid crystal display device of the seventh embodiment further between the during and / or entrance side polarizer and the liquid crystal cell and the outgoing side polarizing element and the liquid crystal cell, the relationship of n _x> n _y and n _z> n _y (However, n _x is the in-plane slow axis direction of the refractive index, n _y is a refractive index in the direction perpendicular in the plane to the slow axis, n _z is a refractive index in the thickness direction) biaxial optically anisotropic satisfying One or two square plates are provided.

  As a mode of disposing the biaxial optical anisotropic plate, a mode in which one sheet is disposed only between the output side polarizer and the liquid crystal cell, and a mode in which one sheet is disposed only between the incident side polarizer and the liquid crystal cell. A mode in which one sheet is disposed between the output side polarizer and the liquid crystal cell, and a mode in which two sheets are disposed only between the output side polarizer and the liquid crystal cell. A mode in which two sheets are disposed only between the polarizer and the liquid crystal cell, a mode in which two sheets are disposed between the output side polarizer and the liquid crystal cell, and between the incident side polarizer and the liquid crystal cell, and the output side polarizer. A mode in which one sheet is disposed between the liquid crystal cell and two sheets are disposed between the incident side polarizer and the liquid crystal cell, and two sheets are disposed between the output side polarizer and the liquid crystal cell. A mode in which one sheet is arranged between the liquid crystal cells is included.

  The biaxial optical anisotropic plate used in the seventh embodiment is the same as that exemplified as the biaxial optical anisotropic plate used in the third embodiment. The arrangement direction of the biaxial optical anisotropic plate can be the same as that shown in the third embodiment.

In the liquid crystal display device of the seventh embodiment, Re _{450 represents} the retardation in the in-plane direction of the biaxial optical anisotropic plate when light having a wavelength of 450 nm and a wavelength of 550 nm is incident at an incident angle of 0 degrees, and When Re ₅₅₀ is set, it is preferable that all the biaxial optical anisotropic plates satisfy the relationship of 0.9 ≦ Re ₄₅₀ / Re ₅₅₀ ≦ 1.1. When the biaxial optical anisotropic plate has such characteristics, the display image of the liquid crystal display device of the seventh embodiment can be made to have the same color balance in observation from the front and oblique directions. .
Retardations Re ₄₅₀ and Re ₅₅₀ are high-speed spectroscopic ellipsometers [J. A. Woolam Co., Ltd., M-2000U], and measured with light having a wavelength of 450 nm and a wavelength of 550 nm being incident.

In the liquid crystal display device according to the seventh embodiment, the protective film on the side close to the liquid crystal cell of the output-side polarizing plate disposed between the input-side polarizer and the output-side polarizer, and an in-plane switching mode in the absence of voltage application When the liquid crystal cell, the protective film on the side near the liquid crystal cell of the incident-side polarizing plate, and all the biaxial optical anisotropic plates are temporarily laminated or laminated, the laminated or laminated body has a wavelength of 550 nm. The retardation R ₀ when the incident light is incident at an incident angle of 0 ° and the retardation R ₄₀ when the light having a wavelength of 550 nm is incident at the incident angle of 40 ° are | R ₄₀ −R ₀ | ≦ 35 nm. Satisfy the relationship.

  In the liquid crystal display device of the seventh embodiment, the light emitted from the light source is transmitted with the light transmittance satisfying the relationship of the formula [2] in the incident side polarizing plate made of the polarizing plate of the present invention. .

(Eighth embodiment of liquid crystal display device)
The liquid crystal display device according to the eighth embodiment includes an output side polarizing plate, an in-plane switching mode liquid crystal cell, an incident side polarizing plate, and a light source in this order.
The exit side polarizing plate includes an exit side polarizer and protective films laminated on both sides of the exit side polarizer. The incident side polarizing plate comprises the polarizing plate of the present invention.

In the liquid crystal display device of the eighth embodiment, further to or between the incident-side polarizer and the liquid crystal cell and the outgoing side polarizing element and the liquid crystal cell, the one that satisfies the relationship of n _z ≧ n _x> n _y The first optical anisotropic plate and a single second optical anisotropic plate satisfying the relationship of n _x > _ny ≧ _nz are provided in a multilayer or stacked manner.
first optical anisotropic plate satisfying the relation of n _z ≧ n _x> n _y is biaxial optical satisfying liquid crystal display device relationship n _x> n _y and n _z> n _y used in the third embodiment You can select from anisotropic plates.
n _x> n _y ≧ n second optical anisotropic plate satisfying the relation _z is the same as the biaxial optical anisotropic plate used in the liquid crystal display device of the second embodiment _{(n x> n y> n} z it may be used as) that satisfies the relationship may be used satisfy the relation of _{n x> n y = n z} .
and n _z ≧ n _x> slow axis of the first optically anisotropic plate satisfying the relation of n _y, it is preferable that the polarization absorption axis of the incident-side polarizer is arranged substantially at a right angle.
n _x> and n _y ≧ n second optical slow axis of the anisotropic plate satisfying the relation of _z, it is preferable that the polarization absorption axis of the incident-side polarizer is arranged substantially at a right angle.

In the liquid crystal display device of the eighth embodiment, the protective film on the side close to the liquid crystal cell of the output-side polarizing plate, which is arranged between the input-side polarizer and the output-side polarizer, an in-plane switching mode in the state where no voltage is applied When the liquid crystal cell, the protective film on the side near the liquid crystal cell of the incident side polarizing plate, the first optical anisotropic plate and the second optical anisotropic plate are made into a laminate or multilayer, the laminate or multilayer is The retardation R ₀ when light having a wavelength of 550 nm is incident at an incident angle of 0 ° and the retardation R ₄₀ when light having a wavelength of 550 nm is incident at an incident angle of 40 ° are | R ₄₀ −R _0. | ≦ 35 nm is satisfied.

  In the liquid crystal display device of the eighth embodiment, the light emitted from the light source is transmitted with the light transmittance satisfying the relationship of the formula [2] in the incident side polarizing plate made of the polarizing plate of the present invention. .

  The liquid crystal display device of the present invention may be provided with other films or layers in addition to the exit side polarizer, the liquid crystal cell, the entrance side polarizer, the light source, the optical anisotropic plate, and the optical filter. For example, one or more of a prism array sheet, a lens array sheet, a light diffusion plate, a light guide plate, a diffusion sheet, and a brightness enhancement film can be arranged at appropriate positions.

  In the liquid crystal display device of the present invention, the white light emitted from the light source passes through the optical filter of the present invention or the polarizing plate of the present invention, and then passes through the liquid crystal cell so that an image can be visually recognized. In the optical filter of the present invention or the polarizing plate of the present invention, the chromaticity coordinates of the transmitted light in the oblique direction are converted into light that is relatively blue or green as compared to the chromaticity coordinates of the transmitted light in the front direction. In the liquid crystal cell, since the chromaticity coordinate of the transmitted light in the oblique direction is converted to light that is relatively red or yellow compared to the chromaticity coordinate of the transmitted light in the front direction, the optical filter of the present invention or the When the light that has passed through the polarizing plate passes through the liquid crystal cell, it becomes white light that balances blue, green, and red in both the front and diagonal directions.

  EXAMPLES Hereinafter, although an Example and a comparative example are shown and this invention is demonstrated further more concretely, this invention is not restrict | limited to the following Example.

Comparative Example 1
An optically isotropic film (made by Nippon Zeon Co., Ltd., trade name “Zeonor film ZF14”) made of a norbornene-based polymer has a transmittance T ^F _{B, N} of 91 at a wavelength of 440 nm. %, The average transmittance T ^F _{B, 60 at} a wavelength of 440 nm in the direction of 60 ° polar angle is 83%, the transmittance T ^F _{G, N in} the front direction at a wavelength of 530 nm is 91%, and the polar angle at a wavelength of 530 nm is in the direction of 60 ° The average transmittance T ^F _{G, 60} is 83%, the transmittance T ^F _{R, N in} the front direction at a wavelength of 620 nm is 92%, and the average transmittance T ^F _{R at a} wavelength of 620 nm in the polar angle direction of 60 degrees. ₆₀ was 83%. Selective reflection did not occur.

The isotropic film and the VA mode liquid crystal panel are overlapped, white light having the emission spectrum shown in FIG. 1 is incident from the isotropic film side, the liquid crystal panel is in a white display state, and the chromaticity of transmitted light is measured. Then, chromaticity coordinates were determined based on the color system (JIS-Z-8701) established in 1931 by the CIE (International Lighting Commission), and the distribution according to the observation angle was determined. The results are shown in FIGS. FIG. 4 shows chromaticity coordinates (x, y). The white circles in FIG. 4 are chromaticity coordinates with a polar angle of 0 degrees. It can be seen that as the observation angle increases, the chromaticity is distributed in the upper right direction. FIG. 5 shows the linear distance (Δxy) between the chromaticity coordinates (x _N , y _N ) in the front direction and the chromaticity coordinates (x _θ , y _θ ) in the oblique direction. It can be seen that (Δxy) increases as the polar angle increases.

Example 1
An optically isotropic film made of a norbornene-based polymer and having a thickness of 100 μm (trade name “Zeonor film ZF14” manufactured by Nippon Zeon Co., Ltd.) was used as a transparent substrate. Plasma treatment was performed on both surfaces of the transparent substrate so that the wetting index was 56 dyne / cm. A solution consisting of 5 parts by weight of polyvinyl alcohol and 95 parts by weight of water was applied to one side of the transparent substrate and dried to form a film. Next, the film was rubbed with a felt roll in a direction parallel to the longitudinal direction of the transparent substrate to obtain an alignment film having an average thickness of 0.1 μm.

  Nematic liquid crystal compound (BASF, trade name “LC242”) 100 parts by weight, chiral agent (BASF, trade name “LC756”) 6.05 parts, photopolymerization initiator (Ciba Specialty Chemicals) , Trade name “Irgacure 907”) 3.28 parts by weight and surfactant (trade name “KH-40”, manufactured by Seimi Chemical Co., Ltd.) 0.23 parts by weight are dissolved in 164 parts by weight of methyl ethyl ketone, and a pore size of 2 μm is dissolved. The coating liquid was prepared by filtering using a fluoroethylene CD / X syringe filter.

On the alignment film, the coating solution was applied to a dry thickness of 1 μm and dried at 100 ° C. for 5 minutes. Subsequently, ultraviolet rays were irradiated at 500 mJ / cm ² to form a cholesteric resin layer, and a circularly polarized light reflector (optical filter B) was obtained.
The collimated white light having the emission spectrum shown in FIG. )).

The transmittance T ^F _{B, N in} the front direction at a wavelength of 440 nm is 62%, the average value T ^F _{B, 60} of the transmittance at a polar angle of 60 degrees in the wavelength 440 nm is 83%, and the transmittance T ^{F in} the front direction at a wavelength of 530 nm. _{G, N} is 88%, the average value T ^F _{G, 60} of the transmittance at a polar angle of 60 degrees at a wavelength of 530 nm is 84%, the transmittance T ^F _{R, N at a} wavelength of 620 nm is 89%, and the wavelength is 620 nm. The average value T ^F _{R, 60} of the transmittance in the direction of 60 ° polar angle was 85%. The central wavelength of the selective reflection band in the front direction was 430 nm, and the central wavelength of the selective reflection band in the direction of the polar angle of 60 degrees was 360 nm.

The optical filter B and the VA mode liquid crystal panel are overlapped, white light having an emission spectrum shown in FIG. 1 is incident from the optical filter B side, the liquid crystal panel is in a white display state, the chromaticity of transmitted light is measured, and the CIE (International Commission on Illumination) Chromaticity coordinates were determined based on the color system (JIS-Z-8701) established in 1931, and the distribution according to the observation angle was determined. The results are shown in FIGS. FIG. 6 shows chromaticity coordinates (x, y). The white circle is the chromaticity when the polar angle is 0 degree. There is little shift of chromaticity coordinates depending on the observation angle, and a small distribution is formed around the white circles. FIG. 7 shows the linear distance (Δxy) between the chromaticity coordinates (x _N , y _N ) in the front direction and the chromaticity coordinates (x _θ , y _θ ) in the oblique direction. It can be seen that (Δxy) does not increase as much as the difference even when the observation angle increases.

Example 2
Nematic liquid crystal compound (BASF, trade name “LC242”) 100 parts by weight, chiral agent (BASF, trade name “LC756”) 3.46 parts by weight, photopolymerization initiator (Ciba Specialty Chemicals) , Trade name "Irgacure 907") 3.21 parts by weight and surfactant (trade name "KH-40", manufactured by Seimi Chemical Co., Ltd.) The coating liquid was prepared by filtering using a fluoroethylene CD / X syringe filter.

On the alignment film, the coating solution was applied to a dry thickness of 1.88 μm and dried at 100 ° C. for 5 minutes. Subsequently, ultraviolet rays were irradiated at 150 mJ / cm ² to form a cholesteric resin layer, and a circularly polarized light reflector (optical filter R) was obtained.
This optical filter R has a transmittance T ^F _{B, N in} the front direction at a wavelength of 440 nm of 83%, an average value T ^F _{B, 60} of a transmittance of 440 nm in the polar angle direction of 60 degrees is 84%, and a front in the wavelength of 530 nm. The transmittance T ^F _{G, N in the} direction is 84%, the average value T ^F _{G, 60} of the transmittance in the polar angle 60 degree direction at the wavelength of 530 nm is 75%, and the transmittance T ^F _{R, N in} the front direction at the wavelength of 620 nm is The average value T ^F _{R, 60} of the transmittance in the direction of 85% and a polar angle of 60 degrees with a wavelength of 620 nm was 75%. The central wavelength of the selective reflection band in the front direction was 760 nm, and the central wavelength of the selective reflection band in the polar angle 60 degrees direction was 640 nm.

The optical filter R and the VA mode liquid crystal panel are overlapped, white light having an emission spectrum shown in FIG. 1 is incident from the optical filter R side, the liquid crystal panel is in a white display state, the chromaticity of transmitted light is measured, and the CIE (International Commission on Illumination) Chromaticity coordinates were determined based on the color system (JIS-Z-8701) established in 1931, and the distribution according to the observation angle was determined. The results are shown in FIGS. FIG. 8 shows chromaticity coordinates (x, y). The white circle is the chromaticity when the polar angle is 0 degree. There is little shift of chromaticity coordinates depending on the viewing angle, and the distribution is small and small. FIG. 9 shows the linear distance (Δxy) between the chromaticity coordinates (x _N , y _N ) in the front direction and the chromaticity coordinates (x _θ , y _θ ) in the oblique direction. It can be seen that (Δxy) does not increase as much as the difference even when the observation angle increases.

(1) Thickness Using a snap gauge (ID-C112BS, manufactured by Mitutoyo Corporation), the thickness is measured at intervals of 5 cm in the width direction of the biaxial optical anisotropic plate to obtain an average value.

(2) Refractive index A high-speed spectroscopic ellipsometer [J. A. Woolam, M-2000U], the refractive index n _xi in the slow axis direction in the plane of the biaxial optical anisotropic plate at a wavelength of 550 nm, and the refractive index n in the direction perpendicular to the slow axis in the plane. _The average value is obtained by measuring _yi and the refractive index n _zi in the thickness direction at 10 points at equal intervals in the width direction of the biaxial optical anisotropic plate.

(3) Retardation R ₀ and R ₄₀
A high-speed spectroscopic ellipsometer [J. A. Using Woolam Co., Ltd., M-2000U], 10 points are measured at equal intervals in the width direction of the optical laminated plate in light having a wavelength of 550 nm, and an average value is calculated.

(4) Retardation Re ₄₅₀ and Re ₅₅₀
A high-speed spectroscopic ellipsometer [J. A. Using Woolam, M-2000U], and measuring 10 points at equal intervals in the width direction of the biaxial optical anisotropic plate in the light of wavelength 450 nm and wavelength 550 nm, the average value Re ₄₅₀ , and the average value Re ₅₅₀ is calculated.

(Preparation of biaxial optical anisotropic plate 2A)
Using a tenter stretching machine, an optically isotropic film made of norbornene-based polymer having a thickness of 100 μm (trade name “ZEONOR FILM ZF14” manufactured by ZEON Corporation) is stretched at a stretching temperature of 134 ° C. and a longitudinal stretching ratio. Simultaneous biaxial stretching is performed at 1.41 times and a transverse stretching ratio of 1.41 times, and one side of the film is corona-treated (one side of the film is treated as a high frequency transmitter (high frequency power supply AGI-024 manufactured by Kasuga Electric Co., Ltd.)) Was used to perform corona discharge treatment at an output of 0.8 kW and a film surface tension of 0.072 N / m) to obtain a biaxial optical anisotropic plate 2A having a thickness of 50 μm.
The refractive indexes of the obtained biaxial optical anisotropic plate 2A were n _x = 1.53213, n _y = 1.53073, and n _z = 1.52713. In addition, Re ₄₅₀ / Re ₅₅₀ of the biaxial optical anisotropic plate 2A was 1.01.

(Preparation of biaxial optical anisotropic plate 2B)
A biaxial optical anisotropic plate 2B having a thickness of 50 μm was obtained in the same manner as the production of the biaxial optical anisotropic plate 2A except that the stretching temperature was 138 ° C.
Refractive index of the obtained biaxial optical anisotropic plate 2B _{is, n x = 1.53137, n y} = 1.53037, were n _z = 1.52827. In addition, Re ₄₅₀ / Re ₅₅₀ of the biaxial optical anisotropic plate 2A was 1.01.

(Preparation of biaxial optical anisotropic plate 2C)
A polycarbonate film with a heat-shrinkable film bonded to both sides via an adhesive layer is uniaxially stretched at a stretching temperature of 152 ° C. and a stretching ratio of 1.3 times using a tenter stretching machine, and biaxial with a thickness of 100 μm. An anisotropic optical anisotropic plate 2C was obtained. Refractive index of the obtained biaxial optical anisotropic plate 2C _{is, n x = 1.58136, n y} = 1.57863, were n _z = 1.58001. In addition, Re ₄₅₀ / Re ₅₅₀ of the biaxial optical anisotropic plate 2C was 1.06.

(Preparation of biaxial optical anisotropic plate 2D)
A layer comprising a styrene-maleic anhydride copolymer [glass transition temperature 100 ° C.], b layer comprising a norbornene ring-opening polymer hydride [glass transition temperature 100 ° C.], and a modified ethylene-vinyl acetate copolymer [Vicat] An unstretched laminate having a configuration of b layer (33 μm) -c layer (8 μm) -a layer (65 μm) -c layer (8 μm) -b layer (33 μm) having a c layer comprising a softening point of 80 ° C. Obtained by coextrusion. The obtained unstretched laminate was uniaxially stretched at a stretching temperature of 135 ° C. and a stretch ratio of 1.5 times using a tenter stretching machine, and further, one side of the film was subjected to corona treatment (one side of the film was Using a high-frequency transmitter (high-frequency power supply AGI-024 manufactured by Kasuga Denki Co., Ltd.), corona discharge treatment was performed at an output of 0.8 KW, and the surface tension of the film was 0.072 N / m). A biaxial optical anisotropic plate 2D was obtained. Refractive index of the obtained biaxial optical anisotropic plate 2D _{is, n x = 1.57024, n y} = 1.56927, were n _z = 1.57048. In addition, Re ₄₅₀ / Re ₅₅₀ of the biaxial optical anisotropic plate 2D was 1.04.

(Preparation of biaxial optical anisotropic plate 2E)
The thickness of each layer of the unstretched laminate is b layer (38 μm) -c layer (10 μm) -a layer (76 μm) -c layer (10 μm) -b layer (38 μm), stretching temperature is 134 ° C., stretching ratio The biaxial optical anisotropic plate 2E having a thickness of 101 μm was obtained in the same manner as the production of the biaxial optical anisotropic plate 2D except that the ratio was increased by 1.7 times.
The refractive indexes of the obtained biaxial optically anisotropic plate 2E were n _x = 1.57041, n _y = 1.56878, and n _z = 1.57082. In addition, Re ₄₅₀ / Re ₅₅₀ of the biaxial optical anisotropic plate 2E was 1.04.

(Preparation of biaxial optical anisotropic plate 2F)
An optically isotropic film Z (made by Nippon Zeon Co., Ltd., trade name “Zeonor film ZF14”) made of a norbornene-based polymer is stretched at 140 ° C. and stretch ratio using a tenter stretching machine. Stretching was performed at 1.41 times to obtain a biaxial optical anisotropic plate 2F having a thickness of 71 μm.
Further, one side of the biaxial optical anisotropic plate 2F was subjected to corona discharge treatment at an output of 0.8 kW using a high frequency transmitter (high frequency power supply AGI-024 manufactured by Kasuga Denki Co., Ltd.), and the surface tension of the film was set to 0.072 N / m.
The refractive indexes of the biaxial optical anisotropic plate 2F were n _x = 1.53072, n _y = 1.52992, and n _z = 1.52937. In addition, Re ₄₅₀ / Re ₅₅₀ of the biaxial optical anisotropic plate 2F was 1.01.

(Preparation of uniaxial optical anisotropic plate 2G)
A layer comprising a styrene-maleic anhydride copolymer [glass transition temperature 130 ° C.], b layer comprising a norbornene ring-opening polymer hydride [glass transition temperature 105 ° C.], and a modified ethylene-vinyl acetate copolymer [Vicat] An unstretched laminate having a c layer composed of a softening point of 80 ° C. and having a configuration of b layer (33 μm) -c layer (8 μm) -a layer (65 μm) -c layer (8 μm) -b layer (33 μm) Was obtained by coextrusion molding. The obtained unstretched laminate was stretched using a longitudinal uniaxial stretching machine at a stretching temperature of 135 ° C. and a stretching ratio of 1.5 times to obtain a uniaxial optical anisotropic plate 2G having a thickness of 118 μm.

Further, one side of the uniaxial optical anisotropic plate 2G was subjected to corona discharge treatment at an output of 0.8 kW using a high frequency transmitter (high frequency power supply AGI-024 manufactured by Kasuga Electric Co., Ltd.), and the surface tension of the film was set to 0.072 N / m.
Refractive index of the uniaxial optical anisotropic plate 2G _{is, n x = 1.58033, n y} = 1.57934, were n _z = 1.58033. Moreover, Re ₄₅₀ / Re ₅₅₀ of the uniaxial optically anisotropic plate 2G was 1.04.

(Production of polarizer)
A 75 μm thick PVA film (manufactured by Kuraray Co., Ltd., Vinylon # 7500) was attached to the chuck and immersed in an aqueous solution of 0.2 g / l iodine and 60 g / l potassium iodide at 30 ° C. for 240 seconds. Subsequently, it was uniaxially stretched 6.0 times in an aqueous solution having a composition of boric acid 70 g / l and potassium iodide 30 g / l and subjected to boric acid treatment for 5 minutes. Finally, it was dried at room temperature for 24 hours to obtain a polarizer having an average thickness of 30 μm and a polarization degree of 99.97%.

Example 3
(Preparation of optical laminate 3)
Triacetyl cellulose film on one side of one surface to a saponification treatment (the film of (Konica Minolta, trade name "KC8UX2M"), 1.5N isopropyl alcohol solution of potassium hydroxide 25 ml / m ² was applied, 25 ° C. And dried for 5 seconds, washed with running water for 10 seconds, and then blown with air at 25 ° C.) to obtain a triacetyl cellulose film F.
Triacetyl cellulose film F, VA mode liquid crystal cell (thickness 2.74 μm, positive dielectric anisotropy, refractive index difference Δn = 0.09884 at a wavelength of 550 nm, pretilt angle 90 degrees), and biaxial The optical anisotropic plate 2A was laminated in this order to produce the optical laminated plate 3. | R ₄₀ −R ₀ | of the obtained optical laminated plate 3 was 22 nm.

(Preparation of exit-side polarizing plate 3A)
A triacetyl cellulose film F was bonded to both surfaces of the polarizer 3a using a polyvinyl alcohol-based adhesive to produce an output-side polarizing plate 3A. At this time, the saponification surface of the triacetyl cellulose film F was directed to the polarizer side.

(Preparation of incident side polarizing plate 3B)
In addition, another polarizer 3b was prepared, and the optical filter B was bonded to one surface thereof, and the biaxial optical anisotropic plate 2A was bonded to the other surface to prepare the incident side polarizing plate 3B. At this time, the transparent substrate side of the optical filter B was directed to the polarizer, and the corona-treated surface of the biaxial optical anisotropic plate 2A was directed to the polarizer.

From the optical filter B side of the incident side polarizing plate 3B, collimated white light having an emission spectrum shown in FIG. 1 is incident at polar angles of 0 degrees and 60 degrees, and the light transmittance is measured by a spectroscope (manufactured by Soma Optics). And trade name "S-2600").
The transmittance T ^P _{B, N in} the front direction at a wavelength of 440 nm is 26%, the average value T ^P _{B, 60} of the transmittance in the polar angle 60 ° direction at the wavelength 440 nm is 27%, and the transmittance T ^{P in} the front direction at a wavelength of 530 nm. _{G, N} is 42%, the average value T ^P _G polar angle direction of 60 degrees of the transmittance at a wavelength of 530 _{nm, 60} 31%, the front direction of the transmittance T ^P _R wavelength _{620nm, N} 43%, and the wavelength 620nm The average value T ^PR _{, 60} of the transmittance in the direction of 60 ° polar angle was 31%. The central wavelength of the selective reflection band in the front direction was 430 nm, and the central wavelength of the selective reflection band in the direction of the polar angle of 60 degrees was 360 nm.

(Production of liquid crystal display device 3)
On the light source device L having the emission spectrum shown in FIG. 2, an incident side polarizing plate 3B, a VA mode liquid crystal cell (thickness 2.74 μm, positive dielectric anisotropy, refractive index difference Δn = 0 at a wavelength of 550 nm) 0.09884, a pretilt angle of 90 degrees) and the output-side polarizing plate 3A were laminated in this order to produce the liquid crystal display device 3 having the configuration shown in FIG. The arrows in FIG. 11 represent the polarization absorption axis for the polarizer and the slow axis for the biaxial optical anisotropic plate.
The biaxial optical anisotropic plate 2A of the incident side polarizing plate 3B was disposed so as to face the liquid crystal cell side. In addition, the polarization absorption axis of the exit-side polarizer 3a and the polarization absorption axis of the entrance-side polarizer 3b are set to be perpendicular to each other. Further, the slow axis in the plane of the biaxial optical anisotropic plate 2A and the polarization absorption axis of the incident side polarizer 3b are set to be perpendicular to each other.
When the chromaticity change by the observation angle of the obtained liquid crystal display device 3 was visually evaluated, the display image of the liquid crystal display device 3 showed almost no chromaticity change in the range of 0 to 80 degrees on the left and right of the display screen.

Example 4
(Preparation of optical laminated plate 4)
Biaxial optical anisotropic plate 2B (referred to as biaxial optical anisotropic plate 2b1), VA mode liquid crystal cell (thickness 2.74 μm, positive dielectric anisotropy, refractive index difference Δn = 0 at wavelength 550 nm) 0.09884, pretilt angle 90 degrees), another biaxial optical anisotropic plate 2B (referred to as biaxial optical anisotropic plate 2b2) was laminated in this order to produce an optical laminated plate 4. The slow axis of the biaxial optical anisotropic plate 2b1 and the slow axis of the biaxial optical anisotropic plate 2b2 were arranged at right angles. | R ₄₀ -R ₀ | of the obtained optical laminated plate 4 was 19 nm.

(Preparation of exit-side polarizing plate 4A)
A triacetyl cellulose film F was bonded to one surface of the polarizer 4a, and a biaxial optical anisotropic plate 2b1 was bonded to the other surface to prepare an output-side polarizing plate 4A. At this time, the saponification-treated surface of the triacetyl cellulose film F was directed to the polarizer, and the corona-treated surface of the biaxial optical anisotropic plate 2b1 was oriented to the polarizer.

(Preparation of incident side polarizing plate 4B)
Further, another polarizer 4b was prepared, and an optical filter B was bonded to one surface of the polarizer 4 and a biaxial optical anisotropic plate 2b2 was bonded to the other surface to prepare an incident side polarizing plate 4B. At this time, the transparent substrate side of the optical filter B was made to face the polarizer, and the corona-treated surface of the biaxial optical anisotropic plate 2b2 was made to face the polarizer.

From the optical filter B side of the incident side polarizing plate 4B, collimated white light having an emission spectrum shown in FIG. 1 is incident at polar angles of 0 degrees and 60 degrees, and the light transmittance is measured by a spectroscope (manufactured by Soma Optics). And trade name "S-2600").
The transmittance T ^P _{B, N in} the front direction at a wavelength of 440 nm is 26%, the average value T ^P _{B, 60} of the transmittance in the polar angle 60 ° direction at the wavelength 440 nm is 27%, and the transmittance T ^{P in} the front direction at a wavelength of 530 nm. _{G, N} is 42%, the average value T ^P _G polar angle direction of 60 degrees of the transmittance at a wavelength of 530 _{nm, 60} 31%, the front direction of the transmittance T ^P _R wavelength _{620nm, N} 43%, and the wavelength 620nm The average value T ^PR _{, 60} of the transmittance in the direction of 60 ° polar angle was 31%. The central wavelength of the selective reflection band in the front direction was 430 nm, and the central wavelength of the selective reflection band in the direction of the polar angle of 60 degrees was 360 nm.

(Production of liquid crystal display device 4)
On the light source device L having the emission spectrum shown in FIG. 2, the incident side polarizing plate 4B, the VA mode liquid crystal cell, and the outgoing side polarizing plate 4A are laminated in this order, and the liquid crystal display having the configuration shown in FIG. Device 4 was made.
The arrows in FIG. 12 represent the polarization absorption axis for the polarizer and the slow axis for the biaxial optical anisotropic plate.

The biaxial optical anisotropic plate 2b1 of the output side polarizing plate 4A is arranged so as to face the liquid crystal cell, and the biaxial optical anisotropic plate 2b2 of the incident side polarizing plate 4B is arranged to face the liquid crystal cell. In addition, the polarization absorption axis of the exit side polarizer 4a and the polarization absorption axis of the entrance side polarizer 4b are set to be perpendicular to each other. Furthermore, the slow axis in the plane of the biaxial optical anisotropic plate 2b1 is perpendicular to the polarization absorption axis of the output side polarizer 4a, and the slow axis in the plane of the biaxial optical anisotropic plate 2b2 The incident side polarizer 4b was set to be perpendicular to the polarization absorption axis.
When the chromaticity change by the observation angle of the obtained liquid crystal display device 4 was visually evaluated, the display image of the liquid crystal display device 4 showed almost no chromaticity change in the range of 0 to 80 degrees on the left and right of the display screen.

Comparative Example 2
A liquid crystal having the structure shown in FIG. 13 is obtained in the same manner as in Example 3 except that the incident side polarizing plate 3C is obtained using the triacetyl cellulose film F instead of the optical filter B and is replaced with the incident side polarizing plate 3B. A display device C was prepared, and the chromaticity change depending on the observation angle was visually evaluated. When the obtained liquid crystal display device C was observed from a direction tilted by 60 degrees or more to the left and right of the display screen, the entire image was light red.

From the incident side polarizing plate 3C, the collimated white light having the emission spectrum shown in FIG. 1 is incident at polar angles of 0 ° and 60 ° from the triacetyl cellulose film F side, and the light transmittance is measured by a spectroscope (Soma Optics). (Trade name “S-2600”).
The transmittance T ^P _{B, N in} the front direction at a wavelength of 440 nm is 39%, the average value T ^P _{B, 60} of the transmittance in the polar angle 60 ° direction at the wavelength 440 nm is 28%, and the transmittance T ^{P in} the front direction at a wavelength of 530 nm. _{G, N} is 42%, the average value T ^P _G polar angle direction of 60 degrees of the transmittance at a wavelength of 530 _{nm, 60} 31%, the front direction of the transmittance T ^P _R wavelength _{620nm, N} 43%, and the wavelength 620nm The average value T ^PR _{, 60} of the transmittance in the direction of 60 ° polar angle was 32%. Selective reflection did not occur.

Example 5
(Preparation of optical laminated plate 5)
Isotropic film Z, IPS mode liquid crystal cell (thickness 2.74 μm, positive dielectric anisotropy, refractive index difference Δn = 0.99884 at a wavelength of 550 nm, pretilt angle 0 degree), biaxial optical difference 2 C of square plates and the isotropic film Z were laminated | stacked in this order, and the optical laminated plate 5 was produced.
| R ₄₀ −R ₀ | of the obtained optical laminated plate 5 was 9 nm.

(Preparation of exit-side polarizing plate 5A)
An isotropic film Z was bonded to both surfaces of a polarizer (referred to as an exit side polarizer 5a) to produce an exit side polarizing plate 5A.

(Preparation of incident side polarizing plate 5B)
An isotropic film Z is bonded to one surface of a polarizer (referred to as an incident-side polarizer 5b), an optical filter B is bonded to the other surface, and a biaxial optical anisotropic is applied to the isotropic film Z. The plate 2C was bonded together to produce the incident side polarizing plate 5B.

From the optical filter B side of the incident side polarizing plate 5B, collimated white light having an emission spectrum shown in FIG. 1 is incident at polar angles of 0 degrees and 60 degrees, and the light transmittance is measured by a spectroscope (manufactured by Soma Optical Co., Ltd.). And trade name "S-2600").
The transmittance T ^P _{B, N in} the front direction at a wavelength of 440 nm is 26%, the average value T ^P _{B, 60} of the transmittance in the polar angle 60 ° direction at the wavelength 440 nm is 27%, and the transmittance T ^{P in} the front direction at a wavelength of 530 nm. _{G, N} is 42%, the average value T ^P _G polar angle direction of 60 degrees of the transmittance at a wavelength of 530 _{nm, 60} 31%, the front direction of the transmittance T ^P _R wavelength _{620nm, N} 43%, and the wavelength 620nm The average value T ^PR _{, 60} of the transmittance in the direction of 60 ° polar angle was 31%. The central wavelength of the selective reflection band in the front direction was 430 nm, and the central wavelength of the selective reflection band in the direction of the polar angle of 60 degrees was 360 nm.

(Production of liquid crystal display device 5)
On the light source device L having the emission spectrum shown in FIG. 2, the incident side polarizing plate 5B, the IPS mode liquid crystal cell, and the outgoing side polarizing plate 5A are laminated in this order, and the liquid crystal display having the configuration shown in FIG. Device 5 was made.
The arrows in the figure represent the polarization absorption axis for the polarizer, the slow axis for the biaxial optical anisotropic plate, and the slow axis when no voltage is applied for the liquid crystal cell.

At this time, the polarization absorption axis of the exit-side polarizer 5a and the polarization absorption axis of the entrance-side polarizer 5b were set to be perpendicular to each other. Further, the slow axis when no voltage is applied to the liquid crystal cell and the polarization absorption axis of the incident side polarizer 5b are set to be perpendicular to each other. The slow axis in the plane of the biaxial optical anisotropic plate 2C and the polarization absorption axis of the incident side polarizer 5b were set to be perpendicular to each other.
When the chromaticity change according to the observation angle of the obtained liquid crystal display device 5 was visually evaluated, the display image of the liquid crystal display device 5 showed almost no chromaticity change in the range of 0 to 80 degrees on the left and right of the display screen. Further, when the display screen of the liquid crystal display device 5 was displayed in black and the screen was observed from an oblique direction, no light leakage was observed, and the display was uniform black.

Example 6
(Preparation of optical laminate 6)
The biaxial optical anisotropic plate 2D, the IPS mode liquid crystal cell, and the biaxial optical anisotropic plate 2E were laminated in this order to produce an optical laminated plate 6.
At this time, the slow axis of the biaxial optical anisotropic plate 2D and the slow axis of the biaxial optical anisotropic plate 2E were arranged at right angles.
| R ₄₀ −R ₀ | of the obtained optical laminated plate 6 was 19 nm.

(Preparation of exit-side polarizing plate 6A)
A triacetyl cellulose film F was bonded to one surface of a polarizer (referred to as an output-side polarizer 4a), and a biaxial optical anisotropic plate 2D was bonded to the other surface to prepare an output-side polarizing plate 6A. . At this time, the saponification-treated surface of the triacetyl cellulose film F was directed to the polarizer, and the corona-treated surface of the biaxial optical anisotropic plate 2D was oriented to the polarizer.

(Preparation of incident side polarizing plate 6B)
Similarly, an optical filter B is bonded to one surface of a polarizer (referred to as an incident side polarizer 6b), and a biaxial optical anisotropic plate 2E is bonded to the other surface, so that an incident side polarizing plate is bonded. 6B was produced.

From the optical filter B side of the incident side polarizing plate 6B, collimated white light having an emission spectrum shown in FIG. 1 is incident at polar angles of 0 degrees and 60 degrees, and the light transmittance is measured by a spectroscope (manufactured by Soma Optical Co., Ltd.). And trade name "S-2600").
The transmittance T ^P _{B, N in} the front direction at a wavelength of 440 nm is 26%, the average value T ^P _{B, 60} of the transmittance in the polar angle 60 ° direction at the wavelength 440 nm is 27%, and the transmittance T ^{P in} the front direction at a wavelength of 530 nm. _{G, N} is 42%, the average value T ^P _G polar angle direction of 60 degrees of the transmittance at a wavelength of 530 _{nm, 60} 31%, the front direction of the transmittance T ^P _R wavelength _{620nm, N} 43%, and the wavelength 620nm The average value T ^PR _{, 60} of the transmittance in the direction of 60 ° polar angle was 31%. The central wavelength of the selective reflection band in the front direction was 430 nm, and the central wavelength of the selective reflection band in the direction of the polar angle of 60 degrees was 360 nm.

(Production of liquid crystal display device 6)
On the light source device L having the emission spectrum shown in FIG. 2, an incident side polarizing plate 6B, an IPS mode liquid crystal cell, and an outgoing side polarizing plate 6A are laminated in this order, and the liquid crystal display having the configuration shown in FIG. Device 6 was made.
At this time, the biaxial optical anisotropic plate 2D of the output side polarizing plate 6A is arranged so as to face the liquid crystal cell, and the biaxial optical anisotropic plate 2E of the incident side polarizing plate 6B is arranged to face the liquid crystal cell. . In addition, the polarization absorption axis of the exit side polarizer 6a and the polarization absorption axis of the entrance side polarizer 6b are set to be perpendicular to each other. In addition, the slow axis when no voltage is applied to the liquid crystal cell and the polarization absorption axis of the incident side polarizer 6b are set to be perpendicular to each other. The slow axis in the plane of the biaxial optical anisotropic plate 2D and the polarization absorption axis of the exit side polarizer 6a are parallel to each other so that the slow axis in the plane of the biaxial optical anisotropic plate 2E and the incident side polarizer are parallel to each other. The polarization absorption axis of 6b was made parallel.

  When the chromaticity change by the observation angle of the obtained liquid crystal display device 6 was visually evaluated, the display image of the liquid crystal display device 6 showed almost no chromaticity change in the range of 0 to 80 degrees on the left and right of the display screen. Moreover, when the display screen of the liquid crystal display device 6 was displayed in black and the screen was observed from an oblique direction, no light leakage was observed, and the display was uniform black.

Comparative Example 3
An incident-side polarizing plate 5C is obtained by using an isotropic film Z instead of the optical filter B, and the structure shown in FIG. 16 is obtained in the same manner as in Example 5 except that the incident-side polarizing plate 5B is replaced with the incident-side polarizing plate 5B. A liquid crystal display device F was produced.
When the chromaticity change due to the observation angle of the obtained liquid crystal display device F was visually evaluated, the image on the display screen of the liquid crystal display device F was thin as a whole when observed from a direction inclined at least 60 degrees to the left and right of the screen. It was red. Further, when the display screen of the liquid crystal display device F was displayed in black and the screen was observed from an oblique direction, no light leakage was observed.

From the isotropic film Z side of the incident side polarizing plate 5C, collimated white light having an emission spectrum shown in FIG. 1 is incident at polar angles of 0 degrees and 60 degrees, and the light transmittance is measured by a spectroscope (Soma). It was measured by an optical company make, brand name “S-2600”).
The transmittance T ^P _{B, N in} the front direction at a wavelength of 440 nm is 39%, the average value T ^P _{B, 60} of the transmittance in the polar angle 60 ° direction at the wavelength 440 nm is 28%, and the transmittance T ^{P in} the front direction at a wavelength of 530 nm. _{G, N} is 42%, the average value T ^P _G polar angle direction of 60 degrees of the transmittance at a wavelength of 530 _{nm, 60} 31%, the front direction of the transmittance T ^P _R wavelength _{620nm, N} 43%, and the wavelength 620nm The average value T ^PR _{, 60} of the transmittance in the direction of 60 ° polar angle was 32%. Selective reflection did not occur.

Example 7
(Optical laminate 7)
Isotropic film Z, IPS mode liquid crystal cell (thickness 2.74 μm, positive dielectric anisotropy, refractive index difference Δn = 0.09884, pretilt angle 0 degree at wavelength 550 nm), uniaxial optical anisotropic The plate 2G and the biaxial optical anisotropic plate 2F were laminated in this order to produce an optical laminated plate 7. At this time, the slow axes of the liquid crystal cell, the uniaxial optical anisotropic plate 2G, and the biaxial optical anisotropic plate 2F when no voltage was applied were all arranged in parallel.
| R ₄₀ −R ₀ | of the obtained optical laminated plate 7 was 8 nm.

(Preparation of exit-side polarizing plate 7A)
An isotropic film Z was bonded to both sides of a polarizer (referred to as an exit-side polarizer 7a) to produce an exit-side polarizing plate 7A.

(Preparation of incident side polarizing plate 7B)
The biaxial optical anisotropic plate 2F and the uniaxial optical anisotropic plate 2G are bonded together so that the slow axes are parallel to obtain a laminated plate. The optical filter B is bonded to one surface of a polarizer (referred to as an incident side polarizer 7b), and the laminated plate is bonded to the other surface so that the biaxial optical anisotropic plate 2F is on the polarizer side, The incident side polarizing plate 7B was produced.

From the optical filter B side of the incident side polarizing plate 7B, collimated white light having an emission spectrum shown in FIG. 1 is incident at polar angles of 0 degrees and 60 degrees, and the light transmittance is measured by a spectroscope (manufactured by Soma Optical Co., Ltd.). And trade name "S-2600").
The transmittance T ^P _{B, N in} the front direction at a wavelength of 440 nm is 26%, the average value T ^P _{B, 60} of the transmittance in the polar angle 60 ° direction at the wavelength 440 nm is 27%, and the transmittance T ^{P in} the front direction at a wavelength of 530 nm. _{G, N} is 42%, the average value T ^P _G polar angle direction of 60 degrees of the transmittance at a wavelength of 530 _{nm, 60} 31%, the front direction of the transmittance T ^P _R wavelength _{620nm, N} 43%, and the wavelength 620nm The average value T ^PR _{, 60} of the transmittance in the direction of 60 ° polar angle was 31%. The central wavelength of the selective reflection band in the front direction was 430 nm, and the central wavelength of the selective reflection band in the direction of the polar angle of 60 degrees was 360 nm.

(Production of liquid crystal display device 7)
On the light source device L having the emission spectrum shown in FIG. 2, an incident side polarizing plate 7B, an IPS mode liquid crystal cell (thickness 2.74 μm, positive dielectric anisotropy, refractive index difference Δn = 0 at a wavelength of 550 nm) 0.09884, pretilt angle 0 degree) and emission side polarizing plate 7A were laminated in this order to produce the liquid crystal display device 7 having the configuration shown in FIG.

At this time, the polarization absorption axis of the exit side polarizer 7a and the polarization absorption axis of the entrance side polarizer 7b were set to be perpendicular to each other. In addition, the slow axis when no voltage is applied to the liquid crystal cell and the polarization absorption axis of the incident side polarizer 7b are set to be perpendicular to each other. The slow axis in the plane of the biaxial optical anisotropic plate 2F is perpendicular to the polarization absorption axis of the incident side polarizer 7b, and the slow axis in the plane of the uniaxial optical anisotropic plate 2G and the incident side polarizer are set. The polarization absorption axis of 7b was set at a right angle.
When the chromaticity change by the observation angle of the obtained liquid crystal display device 7 was visually evaluated, the display image of the liquid crystal display device 7 showed almost no chromaticity change in the range of 0 to 80 degrees on the left and right of the display screen. Moreover, when the display screen of the liquid crystal display device 7 was displayed in black and the screen was observed from an oblique direction, no light leakage was observed, and a uniform black display was obtained.

Claims (18)

Transmittance T ^F _{B, N in} the front direction at a wavelength of 440 nm, average value T ^F _{B, 60} of transmittance in the polar angle of 60 degrees direction at a wavelength of 440 nm, transmittance T ^F _{G, N in} the front direction at a wavelength of 530 nm, wavelength of 530 nm The average value T ^F _{G, 60} of the transmittance in the polar angle direction of 60 degrees, the transmittance T ^F _{R, N in} the front direction at the wavelength of 620 nm, and the average value T ^F _R of the transmittance in the direction of the polar angle of 60 degrees at the wavelength of 620 nm. _{, 60} has a selective reflection band or a selective absorption band satisfying the relationship of the expression [1].
(T ^F _{B, 60} / T ^F _{B, N} )> (T ^F _{G, 60} / T ^F _{G, N} ) ≈ (T ^F _{R, 60} / T ^F _{R, N} ) Equation [1]   The optical filter according to claim 1, which has a selective reflection band or a selective absorption band in a wavelength range of 350 nm to 500 nm in the front direction.   The optical filter according to claim 1, wherein the optical filter has at least one selective reflection band or selective absorption band in a wavelength range of 450 nm to 700 nm in a polar angle direction of 60 degrees.   An illumination device comprising the optical filter according to claim 1 and a light source.   The lighting device according to claim 4, wherein the light source has a light emission intensity peak in a wavelength range of 620 nm to 680 nm.   A liquid crystal display device comprising the illumination device according to claim 4 or 5 and a liquid crystal panel. An exit-side polarizing plate comprising an exit-side polarizer and a protective film laminated on both surfaces of the exit-side polarizer,
Vertical alignment mode liquid crystal cell,
An incident-side polarizing plate comprising an incident-side polarizer and a protective film laminated on both surfaces of the incident-side polarizer, and a liquid crystal display device comprising a light source in this order,
In addition, one or two biaxial optical anisotropic plates are provided between the exit side polarizer and the liquid crystal cell and / or between the entrance side polarizer and the liquid crystal cell,
Furthermore, between the said incident side polarizer and the said light source, The optical filter in any one of Claims 1-3 is provided,
The biaxial optical anisotropic plate, the relationship _{n x> n y> n z} ( however, n _x is the in-plane slow axis direction of the refractive index, n _y is the direction perpendicular in the plane to the slow axis Refractive index, _nz is the refractive index in the thickness direction)
The protective film on the side near the liquid crystal cell in the output side polarizing plate, the liquid crystal cell in a state where no voltage is applied, the protective film on the side near the liquid crystal cell in the incident side polarizing plate, and all the biaxial optical differences. When the square plate is a laminated body, the laminated body has a retardation R ₀ when light having a wavelength of 550 nm is incident at an incident angle of 0 °, and light having a wavelength of 550 nm is incident at an incident angle of 40 °. And the retardation R ₄₀ satisfies the relationship of | R ₄₀ −R ₀ | ≦ 35 nm.
Liquid crystal display device. An output side polarizing plate comprising an output side polarizer and a protective film laminated on both surfaces of the output side polarizer;
In-plane switching mode liquid crystal cell,
An incident-side polarizing plate comprising an incident-side polarizer and a protective film laminated on both surfaces of the incident-side polarizer, and a liquid crystal display device comprising a light source in this order,
In addition, one or two biaxial optical anisotropic plates are provided between the exit side polarizer and the liquid crystal cell and / or between the entrance side polarizer and the liquid crystal cell,
Furthermore, between the said incident side polarizer and the said light source, The optical filter in any one of Claims 1-3 is provided,
The biaxial optical anisotropic plate, the relationship n _x> n _y and n _z> n _y (however, n _x is the in-plane slow axis direction of the refractive index, n _y is orthogonal plane to the slow axis Satisfying the refractive index in the direction of azimuth, _nz is the refractive index in the thickness direction)
The protective film on the side near the liquid crystal cell in the output side polarizing plate, the liquid crystal cell in a state where no voltage is applied, the protective film on the side near the liquid crystal cell in the incident side polarizing plate, and all the biaxial optical differences. When the square plate is a laminated body, the laminated body has a retardation R ₀ when light having a wavelength of 550 nm is incident at an incident angle of 0 °, and light having a wavelength of 550 nm is incident at an incident angle of 40 °. And the retardation R ₄₀ satisfies the relationship of | R ₄₀ −R ₀ | ≦ 35 nm.
Liquid crystal display device. An output side polarizing plate comprising an output side polarizer and a protective film laminated on both surfaces of the output side polarizer;
In-plane switching mode liquid crystal cell,
An incident-side polarizing plate comprising an incident-side polarizer and a protective film laminated on both surfaces of the incident-side polarizer, and a liquid crystal display device comprising a light source in this order,
Furthermore, an optical anisotropic member is provided between the exit side polarizer and the liquid crystal cell or between the entrance side polarizer and the liquid crystal cell,
Furthermore, the optical filter according to any one of claims 1 to 3 is provided between the incident-side polarizer and the light source,
The optical anisotropic _{member, n z ≧ n x> n} y first optical anisotropic plate of one satisfies the relationship, _{and, n x> n y ≧ n} z 1 sheets of second optically anisotropic satisfies the relationship Made of square plate,
A protective film near the liquid crystal cell in the output side polarizing plate, the liquid crystal cell in a state where no voltage is applied, a protective film near the liquid crystal cell in the incident side polarizing plate, and the optically anisotropic member are temporarily stacked. When the substrate is made into a body, the laminate has a retardation R ₀ when light having a wavelength of 550 nm is incident at an incident angle of 0 ° and a retardation R when light having a wavelength of 550 nm is incident at an incident angle of 40 °. ₄₀ satisfies the relationship of | R ₄₀ −R ₀ | ≦ 35 nm.
Liquid crystal display device. It consists of a polarizer and a protective film laminated on both sides of the polarizer,
Transmittance T ^P _{B, N in} the front direction at a wavelength of 440 nm, average value T ^P _{B, 60} of transmittance in a polar angle of 60 degrees direction at a wavelength of 440 nm, transmittance T ^P _{G, N in} the front direction at a wavelength of 530 nm, wavelength 530 nm The average value T ^P _{G, 60} of the transmittance in the polar angle direction of 60 degrees, the transmittance T ^P _{R, N in} the front direction at the wavelength of 620 nm, and the average value T ^P _R of the transmittance in the direction of the polar angle of 60 degrees at the wavelength of 620 nm. _{, 60} , a polarizing plate having a selective reflection band or a selective absorption band that satisfies the relationship of the formula [2].
(T ^P _{B, 60} / T ^P _{B, N} )> (T ^P _{G, 60} / T ^P _{G, N} ) ≈ (T ^P _{R, 60} / T ^P _{R, N} ) Equation [2]   It consists of a polarizer and the protective film laminated | stacked on both surfaces of this polarizer, and when used with a light source, the protective film near the light source among the said protective films is in any one of Claims 1-3. The polarizing plate which is an optical filter of description.   It consists of a polarizer and the protective film laminated | stacked on both surfaces of this polarizer, and when used with a light source, the protective film near the light source among the said protective films is an optical film and Claims 1-3. The polarizing plate which is a laminated body with the optical filter in any one.   The polarizing plate according to claim 10, wherein at least one of the protective films has optical anisotropy.   A liquid crystal panel comprising the polarizing plate according to claim 10.   A liquid crystal display device comprising the liquid crystal panel according to claim 14. An output side polarizing plate comprising an output side polarizer and a protective film laminated on both surfaces of the output side polarizer;
Vertical alignment mode liquid crystal cell,
Incident-side polarizing plate comprising the polarizing plate according to any one of claims 10 to 12,
And a light source comprising a light source in this order,
Furthermore, between the during and / or entrance side polarizer and the liquid crystal cell and the outgoing side polarizing element and the liquid crystal cell, the relationship of _{n x> n y> n z} ( however, n _x is in the in-plane slow axis direction refractive index, n _y is the slow the refractive index in the direction perpendicular to the axis in the plane, n _z is the thickness direction of the one of the biaxial optical anisotropic plate satisfying the refractive index) or 2 Maisonae,
The protective film on the side near the liquid crystal cell in the output side polarizing plate, the liquid crystal cell in a state where no voltage is applied, the protective film on the side near the liquid crystal cell in the incident side polarizing plate, and all the biaxial optical differences. When the square plate is a laminated body, the laminated body has a retardation R ₀ when light having a wavelength of 550 nm is incident at an incident angle of 0 °, and light having a wavelength of 550 nm is incident at an incident angle of 40 °. And the retardation R ₄₀ satisfies the relationship of | R ₄₀ −R ₀ | ≦ 35 nm.
Liquid crystal display device. An output side polarizing plate comprising an output side polarizer and a protective film laminated on both surfaces of the output side polarizer;
In-plane switching mode liquid crystal cell,
Incident-side polarizing plate comprising the polarizing plate according to any one of claims 10 to 12,
And a light source comprising a light source in this order,
Further, the during the exit side polarizer and between and / or the entrance side polarizer and the liquid crystal cell and the liquid crystal cell, the relationship of n _x> n _y and n _z> n _y (however, n _x is plane slow axis direction of the refractive index, n _y is a refractive index in the direction perpendicular in the plane to the slow axis, n _z is one of the biaxial optical anisotropic plate satisfying the refractive index) in the thickness direction or With two,
The protective film on the side near the liquid crystal cell in the output side polarizing plate, the liquid crystal cell in a state where no voltage is applied, the protective film on the side near the liquid crystal cell in the incident side polarizing plate, and all the biaxial optical differences. When the square plate is a laminated body, the laminated body has a retardation R ₀ when light having a wavelength of 550 nm is incident at an incident angle of 0 °, and light having a wavelength of 550 nm is incident at an incident angle of 40 °. And the retardation R ₄₀ satisfies the relationship of | R ₄₀ −R ₀ | ≦ 35 nm.
Liquid crystal display device. An output side polarizing plate comprising an output side polarizer and a protective film laminated on both surfaces of the output side polarizer;
In-plane switching mode liquid crystal cell,
Incident-side polarizing plate comprising the polarizing plate according to any one of claims 10 to 12,
And a light source comprising a light source in this order,
Further, the during the exit side polarizer or between the incident side polarizer and the liquid crystal cell and the liquid crystal cell, n _z ≧ n _x> n first optical anisotropic plate of one that satisfies the relationship of _y And a second optical anisotropic plate satisfying the relationship of n _x > _ny ≧ _nz , or a multilayered or laminated structure,
A protective film near the liquid crystal cell in the output side polarizing plate, the liquid crystal cell in a state where no voltage is applied, a protective film near the liquid crystal cell in the incident side polarizing plate, and the optically anisotropic member are temporarily stacked. When the substrate is made into a body, the laminate has a retardation R ₀ when light having a wavelength of 550 nm is incident at an incident angle of 0 ° and a retardation R when light having a wavelength of 550 nm is incident at an incident angle of 40 °. ₄₀ satisfies the relationship of | R ₄₀ −R ₀ | ≦ 35 nm.
Liquid crystal display device.

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