JP2002049030A - Liquid crystal display - Google Patents

Abstract

[PROBLEMS] To provide an STN type liquid crystal display device which can obtain a bright screen by using external light incident from the front side with high efficiency. A liquid crystal device reflects light of one of two orthogonal polarization components of incident light on the front side of a liquid crystal element in which liquid crystal molecules are twisted at a twist angle of 180 ° to 270 °. A reflective polarizer 10 for transmitting light of the polarization component is disposed, and an absorption polarizer 1
5 and a reflective film 14 are arranged, and light incident from the front side and transmitted through the reflective polarizer 10, the liquid crystal element 1, and the absorption polarizer 15 is reflected by the reflective film 14 and emitted to the front side,
Of the light incident from the front side, the brightness of the entire screen is raised by the light of the one polarization component reflected by the reflective polarizing plate 10.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an STN (super twisted nematic) type liquid crystal display device which performs reflection display using external light.

[0002]

2. Description of the Related Art As a liquid crystal display device, there is an STN (super twisted nematic) type.

In this STN type liquid crystal display device, electrodes are provided on inner surfaces of a front substrate which is a display observation side and a rear substrate which faces the front substrate, and liquid crystal molecules are interposed between these substrates. 180 ° to 270 ° (usually 2
A liquid crystal element provided with a liquid crystal layer twisted at a twist angle of 00 ° to 250 °, and a pair of front and rear absorption polarizing plates (two polarized light beams of incident light orthogonal to each other) interposed between the liquid crystal elements. (A polarizing plate that transmits light of one polarization component and absorbs light of the other polarization component).

There are two types of liquid crystal display devices: one that performs transmissive display using illumination light from a backlight, and one that performs reflective display using external light which is light in the environment in which the liquid crystal display device is used. However, the transmission type liquid crystal display device is
Since large power is consumed to turn on the backlight, it is advantageous to perform reflection display using external light in terms of power saving.

Conventionally, the STN type liquid crystal display device for performing the reflection display has a configuration in which a reflection film is disposed on the rear side of the absorption polarizer disposed on the rear side of the liquid crystal element.

[0006] In this liquid crystal display device, external light incident from the front side, which is the display observation side, is incident on the liquid crystal element as linearly polarized light by the polarizing action of an absorbing polarizer disposed in front of the liquid crystal element. Of the light whose polarization state is controlled by the layer and emitted to the rear side of the liquid crystal element, the light transmitted through the rear absorption polarizing plate is reflected by the reflection film, and the reflected light is reflected by the rear absorption polarizing plate. Then, the light is transmitted through the liquid crystal element and the absorption polarizer on the front side and is emitted to the front side.

[0007]

However, in the above liquid crystal display device, of the incident light from the front side, the light of the polarization component along the transmission axis of the absorption polarizer on the front side transmits through the front side polarizer. Since the light of the polarization component incident on the liquid crystal element and along the absorption axis of the absorption polarizer is absorbed by the polarizer, almost half of the incident light from the front is absorbed by the front absorption polarizer. Light is wasted.

For this reason, the conventional STN for performing reflective display
Type liquid crystal display device, the intensity emitted to the front side, which is the viewing side of the display, is extremely lower than the intensity of the incident light from the front side,
Bright screen cannot be obtained.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a STN type liquid crystal display device which performs reflection display using external light and which can effectively use incident light from the front side and obtain a bright screen. It was done.

[0010]

According to a first liquid crystal display device of the present invention, electrodes are provided on inner surfaces of a front substrate which is a display observation side and a rear substrate which faces the front substrate, respectively. The liquid crystal molecules are 180 ° between these substrates.
A liquid crystal element provided with a liquid crystal layer twisted at a twist angle of up to 270 °, and one of two orthogonal polarization components of incident light, which is disposed on the front side of the liquid crystal element. The liquid crystal device further includes a reflective polarizer that reflects light and transmits light of the other polarization component, and a reflection unit provided on a rear side of the liquid crystal element.

In this liquid crystal display device, incident light from the front side, which is the viewing side of the display, is incident on a reflective polarizing plate arranged on the front side of the liquid crystal element, and of the two orthogonal polarization components of the light. The light of one polarization component is reflected by the reflection polarizing plate, and the light of the other polarization component passes through the reflection polarization plate and enters the liquid crystal element.

The light incident on the liquid crystal element is incident on the reflection means with its polarization state controlled by a liquid crystal layer, and the light reflected by the reflection means is emitted to the front side, which is the display observation side. .

According to this liquid crystal display device, the light incident on the liquid crystal element is the light of the polarized light component transmitted through the reflective polarizing plate among the incident light from the front side. Since the light of the polarization component reflected by the reflective polarizing plate is emitted to the front side, which is the display observation side, and the reflected light raises the brightness of the entire screen, the incident light from the front side is effectively used. , You can get a bright screen.

Further, a second liquid crystal display device according to the present invention comprises:
Electrodes are provided on inner surfaces of a front substrate which is a display observation side and a rear substrate facing the front substrate, and liquid crystal molecules are arranged between these substrates at 180 ° to 270 °.
A liquid crystal element provided with a liquid crystal layer twisted at a twist angle of, and disposed on the front side of the liquid crystal element, reflects light of one of the two orthogonal polarization components of incident light, A reflective polarizing plate that transmits light of the other polarization component, and a transparent film that is disposed on the front side of the reflective polarizing plate and internally reflects light reflected by the reflective polarizing plate and makes the light incident on the reflective polarizing plate again, And a reflection unit provided at a rear side of the liquid crystal element and reflecting at least a part of incident light from the front side.

In this liquid crystal display device, incident light from the front side, which is the display observation side, passes through the transparent film and is incident on the reflective polarizing plate disposed on the front side of the liquid crystal element.
Of the two orthogonal polarization components of the light, one of the polarization components is reflected by the reflection polarizer, and the other polarization component passes through the reflection polarizer and enters the liquid crystal element. .

The reflection polarizer mainly reflects the light of the one polarization component, but also reflects the light of the other polarization component to some extent. Contains not only the light of the one polarization component but also the light of the other polarization component.

The light reflected by the reflective polarizing plate is internally reflected by the transparent film and re-enters the reflective polarizing plate. Of the light, the one polarized component light is reflected and the other is reflected. The light of the polarization component passes through the reflective polarizing plate and enters the liquid crystal element.

The light incident on the liquid crystal element is incident on the reflection means with its polarization state controlled by the liquid crystal layer, and the light reflected by the reflection means is emitted to the front side, which is the display observation side. .

According to this liquid crystal display device, of the two orthogonally polarized light components of the incident light from the front side, the light of the polarized light component transmitted through the reflective polarizer is transmitted through the reflective polarizer and becomes a liquid crystal element. While the light reflected by the reflective polarizer is reflected internally by the transparent film and re-enters the reflective polarizer, of which light having a polarization component transmitted through the reflective polarizer is reflected. Since the light passes through the reflective polarizer and enters the liquid crystal element, the amount of light incident on the liquid crystal element is large. Therefore, a bright screen can be obtained by effectively using the incident light from the front side.

[0020]

DESCRIPTION OF THE PREFERRED EMBODIMENTS As described above, the first liquid crystal display device of the present invention reflects one of the two orthogonally polarized light components of incident light on the front side of the liquid crystal element. The liquid crystal device further includes a reflection polarizing plate that transmits light of the other polarization component, and a reflection unit provided on the rear side of the liquid crystal element. Of the incident light from the front side, the light is reflected by the reflection polarization plate. By raising the brightness of the entire screen with light, a bright screen is obtained by effectively utilizing incident light from the front side.

Further, a second liquid crystal display device according to the present invention comprises:
As described above, on the front side of the liquid crystal element, a reflection polarizer that reflects light of one polarization component and transmits light of the other polarization component among two polarization components of the incident light that are orthogonal to each other is arranged. A transparent film disposed on the front side of the reflective polarizing plate to internally reflect the light reflected by the reflective polarizing plate and to be incident on the reflective polarizing plate again; and a reflection unit provided on the rear side of the liquid crystal element. Of the incident light from the front side, the light of the polarization component transmitted through the reflective polarizer, transmitted through the reflective polarizer and incident on the liquid crystal element, and reflected by the reflective polarizer, the transparent film The light of the polarization component transmitted through the reflective polarizing plate out of the light that has been internally reflected by the reflective polarizing plate and is transmitted through the reflective polarizing plate and is incident on the liquid crystal element from the front side by It is obtained so as to obtain a bright screen by effectively utilizing the Shako.

In the second liquid crystal display device, the transparent film disposed on the front side of the reflective polarizing plate desirably has an optical property of changing the polarization state of transmitted light, and more desirably the transparent film is And a λ / 4 phase plate that gives a phase difference of １ ／ wavelength between the transmitted ordinary light and the extraordinary light.

In this case, it is preferable that the λ / 4 phase plate is arranged such that its slow axis intersects the transmission axis of the reflective polarizer disposed in front of the liquid crystal element at an angle of approximately 45 °. preferable.

In any of the first and second liquid crystal display devices according to the present invention, a diffusing means for diffusing the light reflected by the reflective polarizing plate on the front surface of the reflective polarizing plate disposed in front of the liquid crystal element. Is preferably provided.

In any of the above liquid crystal display devices, one of the two orthogonal polarization components of the incident light is interposed between the liquid crystal element and the reflection polarizing plate disposed on the front side thereof. It is preferable that an absorption polarizer that transmits light and absorbs light of the other polarization component is disposed with its transmission axis substantially parallel to the transmission axis of the reflective polarizer.

Further, in any of the above liquid crystal display devices, at least one of the space between the liquid crystal element and the reflective polarizing plate disposed on the front side thereof and the space between the liquid crystal element and the reflection means provided on the rear side thereof. On the other hand, it is preferable to provide a diffusion layer for diffusing transmitted light.

In any one of the above liquid crystal display devices, the reflection means provided on the rear side of the liquid crystal element is provided with a reflection film, one of two orthogonal polarization components of the incident light. A reflective polarizer that reflects light and transmits light of the other polarization component may be used. Further, when the reflecting means is a reflective film, the incident light is orthogonal to each other between the liquid crystal element and the reflective film. Of the two polarized light components, an absorbing polarizer that transmits light of one polarized light component and absorbs light of the other polarized light component may be provided.

[0028]

1 to 3 show a first embodiment of the present invention. FIG. 1 is an exploded perspective view of a liquid crystal display device.

This liquid crystal display device is an STN type liquid crystal display device which performs reflection display using external light.
And a reflective polarizing plate 10 disposed in front of the liquid crystal element 1.
An absorption polarizer (hereinafter referred to as a front absorption polarizer) 11 disposed between the liquid crystal element 1 and the reflective polarizer 10;
A diffusion layer 12 provided between the reflective polarizer 10 and the absorption polarizer 11, the liquid crystal element 1 and the front absorption polarizer 11;
, A reflection film 14 provided as a reflection means on the rear side of the liquid crystal element 1, and an absorption polarizer disposed between the liquid crystal element 1 and the reflection film 14. Hereinafter, referred to as a rear absorption polarizer).

FIG. 2 is an enlarged cross-sectional view of a part of the liquid crystal element 1. The liquid crystal element 1 has a front transparent substrate 2 which is a display observation side and a rear transparent substrate facing the front substrate 2. 3, transparent electrodes 4 and 5 are respectively provided on the inner surfaces thereof, and the electrodes 4, 5 are provided between these substrates 2 and 3.
And a liquid crystal layer 9 for controlling the polarization state of the transmitted light in accordance with the electric field applied between them.

The liquid crystal element 1 is a simple matrix liquid crystal element. One of the substrates, for example, an electrode 4 provided on the inner surface of the front substrate 2 has a plurality of scanning electrodes formed along the row direction and the other has a plurality of scanning electrodes. The electrodes 5 provided on the inner surface of the rear substrate 3, which is a substrate, are a plurality of signal electrodes formed along the column direction.

Further, on the inner surface of the front substrate 2 of the liquid crystal element 1, a plurality of colors, for example, red, corresponding to a plurality of pixel areas where the plurality of scanning electrodes 4 and the signal electrodes 5 are opposed to each other. Green and blue color filters 6R, 6R
G and 6B are provided. The electrodes 4 on the inner surface of the front substrate 2 are formed on the color filters 6R, 6G, 6B.

The front substrate 2 and the rear substrate 3 are
A liquid crystal layer 9 is provided in a region surrounded by the sealing material between the substrates 2 and 3 at a peripheral portion thereof via a frame-shaped sealing material (not shown).

The liquid crystal molecules of the liquid crystal layer 9 are formed in the vicinity of the substrates 2 and 3 by the alignment films 7 and 8 provided on the inner surfaces of the front and rear substrates 2 and 3 so as to cover the electrodes 4 and 5, respectively. The orientation direction is regulated, and the substrates 2 and 3 are twist-oriented at a twist angle of 180 ° to 270 °.

The twist angle of the liquid crystal molecules of the liquid crystal element 1 is preferably in the range of 200 ° to 250 °. In this embodiment, as shown in FIG. The direction 2a of the liquid crystal molecules is shifted clockwise by approximately 35 ° with respect to the horizontal axis x of the screen when viewed from the front, and the direction 3a of the liquid crystal molecules in the vicinity of the rear substrate 3 is referred to as the horizontal axis x. In contrast, the liquid crystal molecules of the liquid crystal layer 9 of the liquid crystal element 1 are set in a direction deviated counterclockwise by approximately 35 ° when viewed from the front side, and the twist direction of the liquid crystal layer 9 is indicated by a broken line arrow in FIG. 3 to the front substrate 2, and is twisted at a twist angle of approximately 250 ° clockwise as viewed from the front.

The reflective polarizing plate 10 disposed on the front side of the liquid crystal element 1 reflects one of the two orthogonal polarization components of the incident light and transmits the other polarization component. It has the characteristic to make it.

The reflective polarizing plate 10 includes an isotropic thin film (optically isotropic thin film) and an anisotropic thin film (optically anisotropic thin film) made of a polyethylene / naphthalate copolymer or the like. , A multi-layer film composed of multiple layers, which are alternately laminated with the same direction in which the refractive indexes of all the anisotropic thin films become maximum.

That is, the reflective polarizing plate 10 has a reflection axis 10 s in a direction in which the refractive index of the anisotropic thin film is different from the refractive index of the isotropic thin film, and the refractive index of the anisotropic thin film is the same. The same direction as the refractive index of the isotropic thin film (reflection axis 10s
(In the direction perpendicular to the direction of the transmission axis).

FIG. 3 is an enlarged sectional view of a part of the reflection polarizing plate 10 with hatching omitted.
0 is the two orthogonal polarization components S, P of the incident light I
Among them, the light Is of one polarization component S having a vibration plane along the reflection axis 10s is reflected (reflected at each interface between an isotropic thin film and an anisotropic thin film alternately stacked in a large number).
Then, the light Ip of the other polarization component P having a vibration plane along the transmission axis 10p is transmitted.

The reflective polarizing plate 10 has the same characteristics with respect to the incident light from the front side and the incident light from the rear side, and has two orthogonal polarization components included in the incident light. The light of one polarization component along the reflection axis 10s is reflected, and the light of the other polarization component along the transmission axis 10p is transmitted.

In this embodiment, the reflection polarizing plate 1 is used.
0 is subjected to a roughening process, and the front surface is formed as a diffusing surface 10 for diffusing the light reflected by the reflective polarizing plate 10.
a. As shown in FIG. 3, the diffusion surface 10a is an uneven surface in which minute groove-shaped concave portions or dot-shaped concave portions are densely arranged.

The reflection polarizing plate 10 has a transmission axis 10p.
With respect to the liquid crystal molecule alignment direction 2 a in the vicinity of the front substrate 2 of the liquid crystal element 1, approximately 45 counterclockwise as viewed from the front.
It is arranged in a direction shifted by 10 ° (a direction shifted approximately 10 ° counterclockwise when viewed from the front with respect to the horizontal axis x of the screen).

The front absorption polarizing plate 11 disposed between the liquid crystal element 1 and the reflection polarizing plate 10 and the rear absorption polarization plate 15 disposed between the liquid crystal element 1 and the reflection film 13 have one side. , And has an absorption axis (not shown) in a direction orthogonal to the transmission axes 11a and 15a. Of the two orthogonal polarization components of the incident light, the transmission axis 11a
The light of one polarization component having a vibration plane along a, 15a is transmitted, and the light of the other polarization component having a vibration plane along a direction (absorption axis) orthogonal to the plane is absorbed.

The front absorption polarizing plate 11 is arranged so that its transmission axis 11a is substantially parallel to the transmission axis 10p of the reflection polarizing plate 10.
5 is a direction in which the transmission axis 15a is displaced approximately 65 ° counterclockwise as viewed from the front with respect to the transmission axis 10p of the reflective polarizer 10 and the transmission axis 11a of the front absorption polarizer 11 (horizontal axis x of the screen). (In a direction deviated approximately 75 ° counterclockwise when viewed from the front side).

The liquid crystal element 1 and the reflective polarizing plate 1
The diffusion layer 12 provided between 0 and 0 is an optical film having good diffusivity and transparency, for example, a transparent film having a roughened surface, a transparent film in which scattering particles are dispersed, and a fine film on one surface. The lens is made of a lens film or the like in which various lenses are arrayed.

On the other hand, the compensating plate 13 provided between the liquid crystal element 1 and the front absorption polarizing plate 11 is provided to suppress display band color peculiar to the STN type liquid crystal display device and perform white display. Have been. The compensator 13 is formed of a phase plate, and its slow axis 13a is displaced approximately 85 ° counterclockwise as viewed from the front with respect to the liquid crystal molecule alignment direction 2a near the front substrate 2 of the liquid crystal element 1. (A direction deviated approximately 50 ° counterclockwise as viewed from the front with respect to the horizontal axis x of the screen). The value of the product Δnd of the birefringence Δn of the liquid crystal of the liquid crystal element 1 and the thickness d of the liquid crystal layer is about 780 nm, and the retardation of the compensator (phase plate) 13 is about 570 nm.

In this liquid crystal display device, external light (non-polarized light) incident from the front side is incident on the reflective polarizer 10, and of the two orthogonal polarization components of the incident light, the reflective polarizer is used. The light of one polarization component along the 10 reflection axis 10s is reflected forward by the reflection polarization plate 10, and the light of the other polarization component along the transmission axis 10p of the reflection polarization plate 10 is reflected by this reflection polarization plate. It passes through the plate 10.

The light transmitted through the reflective polarizer 10, that is, the linearly polarized light having a polarization component along the transmission axis 10 p of the reflective polarizer 10, transmits through the diffusion layer 12 and passes through the front absorption polarizer 1.
1, the light of the polarization component along the direction (absorption axis) substantially perpendicular to the transmission axis 11a of the front absorption polarizing plate 11 is absorbed by the front absorption polarizing plate 11, The light of the polarization component along the transmission axis 11a of the front absorption polarizing plate 11 passes through the front absorption polarizing plate 11 to become linearly polarized light having a high degree of polarization.
To enter the liquid crystal element 1.

The light incident on the liquid crystal element 1 changes its polarization state by the birefringence action of the liquid crystal layer 9 according to the alignment state of the liquid crystal molecules which is changed by the electric field applied between the electrodes 3 and 4 of the liquid crystal element 1. Instead, the light is emitted to the rear side of the liquid crystal element 1 and enters the rear absorption polarizer 15.

Then, of the light incident on the rear absorption polarizer 15, the light of the polarization component along the direction (absorption axis) substantially orthogonal to the transmission axis 15a of the rear absorption polarizer 15 is The light of the polarization component absorbed by the rear absorption polarizer 15 and along the transmission axis 15a of the rear absorption polarizer 15 is transmitted through the rear absorption polarizer 15 and reflected by the reflection film 14, and The reflected light is reflected by the rear absorption polarizer 15.
, Liquid crystal element 1, compensator 13, front absorption polarizer 11
Then, the light passes through the diffusion layer 12 and the reflective polarizing plate 10 and is emitted to the front side.

That is, the liquid crystal element 1 changes the polarization state of the light emitted to the rear side according to the alignment state of the liquid crystal molecules, and transmits the light through the rear absorption polarizer 15 according to the polarization state. Control the rate.

An electric field is applied between the electrodes 3 and 4 of the liquid crystal element 1 so as to control stepwise between an electric field having a value at which the darkest dark display is obtained and an electric field having a value at which the brightest bright display is obtained. Then, an image having a gradation in brightness is displayed.

In the liquid crystal display device of this embodiment, the light transmitted through each pixel area of the liquid crystal element 1 receives the color of the color filters 6R, 6G, 6B corresponding to the pixel area, respectively.
For example, the light emitted from each pixel region is colored red, green, and blue to be colored in any one of red, green, and blue, and accordingly, the intensity of these red, green, and blue emitted light is obtained. By changing stepwise, a multicolor image such as a full-color image can be displayed.

Further, in this embodiment, since the compensating plate 13 is provided, it is possible to suppress the banding of the display peculiar to the STN type liquid crystal display device, and to display a multicolor image with good color quality.

The liquid crystal display device has a liquid crystal element 1
Reflected light that reflects light of one polarization component along the reflection axis 10s and transmits light of the other polarization component along the transmission axis 10p among the two orthogonal polarization components of the incident light. Since the plate 10 is arranged, as described above, of the external light incident from the front side, the light of the polarization component along the reflection axis 10 of the reflection polarizing plate 10 is transmitted to the front side by the reflection polarizing plate 10. The light is reflected, and the brightness of the entire screen is raised by the reflected light. Therefore, according to this liquid crystal display device, a bright screen can be obtained by using the external light incident from the front side with high efficiency.

In a liquid crystal display device that performs reflection display using external light, the direction inclined to the upper edge of the screen with respect to the normal line of the screen to some extent is directed to the brightest direction in the usage environment. Since it is usually used, external light mainly enters the reflective polarizing plate 10 from a direction inclined obliquely with respect to its normal, and of the light, The light of the polarization component along the reflection axis 10 s is reflected forward at a reflection angle corresponding to the angle of incidence on the reflection polarizing plate 10.

On the other hand, since the display of the liquid crystal display device is observed from the front direction of the screen (a direction near the normal to the screen), the reflected light of the external light reflected forward by the reflective polarizing plate 10 is reflected. Of which contributes to raising the brightness of the screen,
That is, the light seen by the display observer is the reflected light emitted in the front direction, and the reflected light emitted in the direction oblique to the front direction is not seen by the display observer.

Therefore, in this liquid crystal display device, the brightness of the whole screen is raised by the reflected light of the external light reflected forward by the reflective polarizing plate 10, but the dark display by the reflected light of the external light is performed. The rise of the darkness is small, so that a sufficient contrast can be obtained, and the screen is hardly seen by the reflected light of the external light.

Further, in this embodiment, since the front surface of the reflection polarizing plate 10 is a diffusion surface 10a, the light reflected by the reflection polarization plate 10 is diffused by the diffusion surface 10a, and the light is reflected by the reflection polarization plate 10. The glare on the screen due to the reflected external light can be almost eliminated.

In this embodiment, the front surface of the reflective polarizing plate 10 is roughened to form a diffusion surface 10a. Instead, the front surface of the reflective polarizing plate 10 may be provided with a roughened film or dispersed scattering particles. A diffusion layer made of a film or the like may be provided, and the light reflected by the reflective polarizing plate 10 may be diffused by the diffusion layer.

In the above embodiment, the absorption polarizer 11 is disposed between the liquid crystal element 1 and the reflective polarizer 10 disposed on the front side thereof, and the transmission axis 11a of the absorption polarizer 11 is set to the transmission axis 10p of the reflective polarizer 10. Since they are arranged substantially in parallel, light incident from the front side and transmitted through the reflective polarizer 10 can be incident on the liquid crystal element 1 as linearly polarized light having a high degree of polarization by the absorption polarizer 11, Therefore, a display with better contrast can be obtained.

Since the reflective polarizer 10 transmits light having a polarization component along the transmission axis 10p at a higher transmittance than the absorption polarizer 11, the reflective polarizer 10 reflects light with the liquid crystal element 1 as described above. Even if the absorbing polarizer 11 is arranged between the polarizer 10 and the polarizer 10, light of sufficient intensity can be incident on the liquid crystal element 1.

That is, the absorbing polarizer 11 contains a substance (a dichroic substance such as iodine) that absorbs light of a polarized component having a vibration plane along one direction. By orienting in the direction, among the polarization components of the incident light that are substantially orthogonal to each other, one direction, that is, light of one polarization component having a vibration plane along an absorption axis (not shown) is absorbed, and in the one direction. Light of a polarization component having a vibration plane along the transmission axis 11a is transmitted in a direction substantially perpendicular to the transmission axis. However, since the orientation state of the absorbing substance is disturbed, the vibration plane along the transmission axis 11a is changed. The light of the polarized component that it has is also absorbed to some extent.

On the other hand, since the reflection polarizing plate 10 does not contain a substance that absorbs light, its transmission axis 10p
The light of the polarized light component having a vibration plane along is transmitted at a high transmittance.

Therefore, the intensity of the light transmitted through both the reflective polarizing plate 10 and the absorbing polarizer 11 is only slightly lower than the intensity of the light transmitted only through the absorbing polarizer 11. Therefore, light of sufficient intensity can be incident on the liquid crystal element 1.

Further, in the above embodiment, the diffusion layer 12 is provided between the liquid crystal element 1 and the reflective polarizer 10 disposed in front of the liquid crystal element 1 (between the reflective polarizer 10 and the absorption polarizer 11). The light reflected by the reflection film 14 and emitted to the front side is diffused by the diffusion layer 12 so that a display having a uniform luminance distribution can be obtained. It is possible to eliminate the so-called reflection of the outside scene that appears on the surface.

As described above, the diffusion layer 12 may be any of a transparent film having a roughened surface, a transparent film having dispersed scattering particles, and a lens film having fine lenses arranged on one surface. When using a roughened film or a scattered particle dispersion film, the haze value is preferably about 30 to 32. Use of a roughened film or a scattered particle dispersion film having such a haze value is preferable. Thereby, a display with high front luminance can be obtained.

The diffusion layer 12 is more preferably the lens film. According to this lens film, a higher front luminance can be obtained, and the lens film does not change the polarization state of the transmitted light. In both the transmissive display mode and the transmissive display mode, it is possible to increase the emission rate of the incident light, and obtain a brighter display with good contrast.

In the above embodiment, the diffusion layer 12 is provided between the reflective polarizing plate 10 and the absorbing polarizing plate 11.
As in the second embodiment shown in FIG. 4, the diffusion layer 12 includes the absorbing polarizer 11 and the compensator 1 on the front side of the liquid crystal element 1.
3 may be provided.

The diffusion layer 12 is formed on the liquid crystal element 1.
And the reflective film 14 disposed on the rear side (the liquid crystal element 1).
Between the liquid crystal element 1 and the reflective polarizer 10, and between the liquid crystal element 1 and the reflective polarizer 10. It may be provided both between the element 1 and the reflection film 14.

In the liquid crystal display devices according to the first and second embodiments, the reflection film 14 is disposed as a reflection means on the rear side of the liquid crystal element 1. The reflecting means to be arranged may be a semi-transmissive reflective film. By using this transflective film, in an environment where external light of sufficient brightness can be obtained, reflective display using external light is performed, and sufficient brightness is obtained. When the outside light cannot be obtained, the backlight can be turned on to perform transmissive display using the illumination light.

Further, in the first and second embodiments, the absorbing polarizer 11 is provided between the reflective polarizer 10 and the compensator 13, but the reflective polarizer 10 having a sufficiently high degree of polarization is provided.
, A liquid crystal display device may be configured without providing the absorbing polarizing plate 11.

In this case, as described above, the reflective polarizing plate 10 does not contain a substance that absorbs light, and thus transmits the polarized component light having a vibration plane along the transmission axis 10p at a high transmittance. . Therefore, of the light incident on the liquid crystal display device, the light incident on the liquid crystal element 1 via the compensator 13 can be increased, and a bright reflective display can be obtained.

FIG. 5 is an exploded perspective view of a liquid crystal display device according to a third embodiment of the present invention. This liquid crystal display device includes a liquid crystal element 1 and a reflective polarizing plate disposed in front of the liquid crystal element 1. 10, an absorption polarizer 11 disposed between the liquid crystal element 1 and the reflection polarizer 10, a diffusion layer 12 provided between the reflection polarizer 10 and the absorption polarizer 11, 1 and a compensating plate 13 disposed between the front absorption polarizing plate 11 and a reflection film 1 provided on the rear side of the liquid crystal element 1.
4 is provided.

The liquid crystal display of this embodiment is different from the liquid crystal display of the first embodiment in that the rear absorption polarizer 1
5 is omitted, and the directions of the optical axes of the reflection polarizer 10, the absorption polarizer 11, and the compensator 13 are different, and the configuration of the liquid crystal element 1 is the same as that of the first embodiment. ,
Duplicate descriptions are given the same reference numerals in the drawings and are omitted.

In this embodiment, the reflection polarizing plate 10
Is a direction in which the transmission axis 10p is displaced approximately 85 ° counterclockwise as viewed from the front side with respect to the liquid crystal molecule alignment direction 2a near the front substrate 2 of the liquid crystal element 1 (with respect to the horizontal axis x of the screen).
(In a direction approximately 55 ° counterclockwise as viewed from the front), and the absorbing polarizer 11 has its transmission axis 1
1a is arranged substantially parallel to the transmission axis 10p of the reflective polarizing plate 10.

The compensating plate 13 is formed of a phase plate, and its slow axis 13a is positioned on the right side when viewed from the front with respect to the liquid crystal molecule alignment direction 2a near the front substrate 2 of the liquid crystal element 1. It is arranged in a direction deviated by about 10 ° around (a direction deviated by about 155 ° counterclockwise as viewed from the front with respect to the horizontal axis x of the screen). The value of Δnd of the liquid crystal element 1 is about 780 nm, and the compensator (phase plate) 13
Has a retardation of about 570 nm.

In this liquid crystal display device, external light (non-polarized light) incident from the front side is incident on the reflective polarizer 10, and of the two orthogonal polarization components of the incident light, the reflective polarizer is used. The light of the polarization component along the 10 reflection axis 10s is reflected forward by this reflection polarizing plate 10,
Light having a polarization component along the transmission axis 10p of the reflective polarizing plate 10 is transmitted through the reflective polarizing plate 10.

The light transmitted through the reflective polarizing plate 10, that is, the linearly polarized light having the polarization component along the transmission axis 10p of the reflective polarizing plate 10, passes through the diffusion layer 12 and enters the absorbing polarizing plate 11, where Of the light, the transmission axis 1 of the absorption polarizer 11
1a is absorbed by the absorption polarizing plate 11, and the light of the polarization component along the transmission axis 11a of the absorption polarizing plate 11 is absorbed by the absorption polarizing plate 11. The light passes through the polarizing plate 11 and becomes linearly polarized light having a high degree of polarization, and the light passes through the compensating plate 13 and enters the liquid crystal element 1.

The light incident on the liquid crystal element 1 changes its polarization state due to the birefringence of the liquid crystal layer of the liquid crystal element 1, exits to the rear side of the liquid crystal element 1, and is reflected by the reflection film 14.

The reflected light reflected by the reflection film 14 enters the liquid crystal element 1 again from the rear side, changes its polarization state further by the birefringence of the liquid crystal layer 9, and exits to the front side of the liquid crystal element 1. Then, the light passes through the compensating plate 13 and enters the absorbing polarizing plate 11 from the rear side.

Then, of the light incident on the absorbing polarizing plate 11 from the rear side, the transmission axis 11 of the absorbing polarizing plate 11 is used.
The light of the polarization component along the direction (absorption axis) substantially orthogonal to a is absorbed by the absorption polarizer 11, and the light of the polarization component along the transmission axis 11a of the absorption polarizer 11 is
The light passes through the absorbing polarizer 11, passes through the diffusion layer 12 and the reflective polarizer 10, and is emitted to the front side.

That is, the liquid crystal display device of this embodiment is
A polarizer that causes incident light from the front side to enter the liquid crystal element 1 as linearly polarized light on the reflective polarizer 10 and the absorption polarizer 11 disposed on the front side of the liquid crystal element 1 and transmission of light transmitted through the liquid crystal element 1 Is also used as an analyzer that controls according to the polarization state. According to this liquid crystal display device, the rear absorption polarizer 15 in the liquid crystal display devices of the above-described first and second embodiments is used. Since there is no light absorption, a brighter screen can be obtained than in the liquid crystal display devices of the first and second embodiments.

In the third embodiment, the diffusion layer 12
Is provided between the reflective polarizer 10 and the absorbing polarizer 11, but the diffusion layer 12 is provided between the absorbing polarizer 11 and the liquid crystal element 1 as in the fourth embodiment shown in FIG. It may be provided between the front compensator 13 and the fifth compensator 13 shown in FIG.
As in the embodiment, the diffusion layer 12 may be omitted.

FIG. 8 is an exploded perspective view of a liquid crystal display device according to a sixth embodiment of the present invention. The liquid crystal display device of this embodiment is provided with a liquid crystal element 1 and a front side of the liquid crystal element 1. Reflective polarizer 10, liquid crystal element 1 and reflective polarizer 10
And the liquid crystal element 1
Compensator 13 arranged between the front side absorbing polarizing plate 11 and
And a reflection film 14 provided on the rear side of the liquid crystal element 1. Further, the light reflected by the reflection polarization plate 10 is internally reflected on the front side of the reflection polarization plate 10 to form the reflection polarization plate. In this example, a transparent film 16 for re-entering the light source 10 is disposed.

The liquid crystal display device of this embodiment is similar to that of FIG.
Of the liquid crystal display of the fifth embodiment shown in FIG.
The transparent film 16 is disposed on the front side of
The directions of the optical axes of the reflective polarizer 10, the absorbing polarizer 11, and the compensator (phase plate) 13, the Δnd of the liquid crystal element 1, and the retardation of the compensator 13 are the same as those in the third to fifth embodiments. Therefore, the duplicate description is omitted by attaching the same reference numerals to the drawings.

The transparent film 16 has an optical property to change the polarization state of the transmitted light, for example, gives a phase difference between the ordinary light and the extraordinary light of the transmitted light to change the polarization state of the transmitted light. In this embodiment, a λ / 4 phase plate which gives a phase difference of １ ／ wavelength between ordinary light and extraordinary light is used as the transparent film (hereinafter referred to as a phase plate) 16 in this embodiment. ing.

This phase plate 16 is, as shown in FIG.
The slow axis 16a is arranged so as to be substantially 100 ° counterclockwise as viewed from the front with respect to the horizontal axis x of the screen. In other words, the slow axis 16a of the phase plate 16 is the same as the transmission axis 1 of the reflective polarizer 10 disposed in front of the liquid crystal element 1.
It intersects at about 45 ° with 0p.

In the liquid crystal display device of this embodiment, external light incident from the front side is transmitted through the phase plate 16 and is incident on the reflective polarizing plate 10, and of the two orthogonally polarized components of the incident light. , The reflection axis 10s of the reflection polarizing plate 10
Is reflected by the reflective polarizing plate 10, and light of the other polarized component along the transmission axis 10p of the reflective polarizing plate 10 is transmitted through the reflective polarizing plate 10 and absorbed. The light passes through the polarizing plate 11 and the compensator 13 and enters the liquid crystal element 1.

The light of the one polarization component reflected by the reflection polarizing plate 10 is incident on the phase plate 16 from the rear side, and is generated by the interface between the front surface of the phase plate 16 and the air layer which is the outside air. While being internally reflected, the polarization state is changed by the phase difference of the phase plate 16 and re-enters the reflective polarizer 10.
Light whose polarization state has been changed to the other polarization component along the transmission axis 10p of 0 passes through the reflective polarizer 10, passes through the absorption polarizer 11 and the compensator 13, and enters the liquid crystal element 1. .

That is, in this liquid crystal display device, of the two orthogonally polarized light components of the external light incident from the front side, the light of the polarized light component transmitted through the reflective polarizer 10 and the light reflected by the reflective polarizer 10 are reflected. Of the light which is internally reflected by the phase plate 16 and whose polarization state has been changed and is incident on the reflective polarizing plate 10 again, both of the polarized component light transmitted through the reflective polarizing plate 10 are reflected by the reflection plate. The light passes through the polarizing plate 10 and becomes incident light on the liquid crystal element 1.

The light whose polarization state has been changed by the phase plate 16 and re-enters the reflective polarizer 10 is one of the light reflected by the reflective polarizer 10 and incident on the phase plate 16 from the rear side. The light is incident on the interface between the front surface of the phase plate 16 and the air layer as the outside air at a total reflection angle, and is smaller than the total reflection angle (closer to vertical) than the total reflection angle on the front surface of the phase plate 16. Is incident on the phase plate 1
6, and is emitted to the front side to become leaked light.

However, in this embodiment, since the front surface of the reflective polarizing plate 10 is a diffusion surface 10a, the light of the one polarized component reflected by the reflective polarizing plate 10 is diffused by the diffusion surface 10a. More reflected light,
The light can be incident on the phase plate 16 at an incident angle at which the light is internally reflected. Therefore, the amount of light whose polarization state is changed by the phase plate 16 and re-enters the reflective polarizing plate 10 is increased, and Can be reduced.

Further, in this embodiment, the phase plate 16
Since a λ / 4 phase plate that gives a phase difference of １ ／ wavelength between the ordinary light and the extraordinary light of the transmitted light is used, the λ / 4 phase plate 16 is reflected by the reflective polarizing plate 10 and The light that enters from the rear side, is internally reflected by the λ / 4 phase plate 16, and exits to the rear side is reflected by the reflection polarizing plate 10.
Of the polarization state of a polarization component (polarization component transmitted through the reflective polarizer 10) orthogonal to one of the polarized light components reflected by the light, and most of the light incident on the reflective polarizer 10 again is reflected by the reflected polarized light. The light can pass through the plate 10 and enter the liquid crystal element 1.

The effect of the use of the λ / 4 phase plate 16 is that the λ / 4 phase plate 16 has its slow axis 16a substantially aligned with the transmission axis 10p of the reflective polarizing plate 10 as described above. It is most effective when arranged crossing at an angle of 45 °.

The liquid crystal element 1 transmits through the reflective polarizer 10 and transmits through the absorption polarizer 11 and the compensator 13.
Incident on the liquid crystal element 1, the polarization state is changed by the birefringence of the liquid crystal layer of the liquid crystal element 1, the light is emitted to the rear side of the liquid crystal element 1, and is reflected by the reflection film 14.

The reflected light reflected by the reflection film 14 enters the liquid crystal element 1 again from the rear side, changes its polarization state by the birefringence of the liquid crystal layer, and exits to the front side of the liquid crystal element 1. , Transmitted through the compensating plate 13 and incident on the absorbing polarizer 11 from the rear side, and of the light, a polarized component along a direction (absorption axis) substantially orthogonal to the transmission axis 11 a of the absorbing polarizer 11. Is absorbed by the absorbing polarizer 11 and the transmission axis 11 of the absorbing polarizer 11
The light of the polarization component along a is transmitted through the absorption polarizer 11, transmitted through the diffusion layer 12, the reflective polarizer 10, and the phase plate 16 and emitted to the front side.

That is, in this liquid crystal display device, by disposing the reflective polarizer 10 on the front side of the liquid crystal element 1 and arranging the position plate 16 on the front side of the reflective polarizer 10, the external light incident from the front side can be obtained. Of the two orthogonal polarization components of the light, the polarization component light transmitted through the reflective polarizer 10 is reflected by the reflective polarizer 10, is internally reflected by the phase plate 16, and changes its polarization state. Then, both the light of the polarization component transmitted through the reflective polarizing plate 10 out of the light incident on the reflective polarizing plate 10 again is transmitted through the reflective polarizing plate 10 to be incident on the liquid crystal element 1. Therefore, the bright display can be brightened by using the external light incident from the front side with high efficiency.

Moreover, in this liquid crystal display device, the reflective polarizing plate 10 reflects one of two orthogonally polarized light components of the external light incident from the front side. Is the phase plate 1 as described above.
6. The polarization state is changed by the
And the light whose polarization state has been changed to the other polarization component of the light is incident on the liquid crystal element 10, so that the light reflected by the reflective polarizing plate 10 passes through the phase plate 16 and is directed forward. The emitted light leakage is small, and therefore, it is possible to suppress the rise of the darkness of the dark display due to the light leakage and obtain a good contrast.

The liquid crystal display device of this embodiment has a reflective polarizer 10 and an absorption polarizer 11 disposed in front of the liquid crystal element 1, similarly to the liquid crystal display devices of the third to fifth embodiments described above. In addition, a polarizer that makes incident light from the front side incident on the liquid crystal element 1 as linearly polarized light and an analyzer that controls the transmission of light transmitted through the liquid crystal element 1 according to the polarization state thereof are used. Therefore, there is no light absorption by the rear absorption polarizer 15 in the liquid crystal display devices of the first and second embodiments described above, and therefore, a brighter screen can be obtained.

In the third to sixth embodiments described above,
The reflection film 14 is used as a reflection means provided on the rear side of the liquid crystal element 1, and the reflection film 14 is disposed on the rear side of the liquid crystal element 1, but is provided on the inner surface of the rear substrate 3 of the liquid crystal element 1. 5 (see FIG. 2) may be formed of a metal film having a high reflectivity, and this electrode 5 may also serve as a reflection means.

In the liquid crystal display devices of the above-described first to sixth embodiments, in order to make the linearly polarized light having a higher degree of polarization incident on the liquid crystal element 1, the liquid crystal element 1 and the reflection disposed in front of the liquid crystal element 1 are arranged. The absorbing polarizer 11 is disposed between the polarizer 10 and the transmission axis 11a of the absorption polarizer 11 so as to be substantially parallel to the transmission axis 10p of the reflective polarizer 10, but the absorption polarizer 11 may be omitted. .

FIG. 9 is an exploded perspective view of a liquid crystal display device according to a seventh embodiment of the present invention. The liquid crystal display device of this embodiment is provided with a liquid crystal element 1 and a front side of the liquid crystal element 1. Reflective polarizer 10, liquid crystal element 1 and reflective polarizer 10
And a reflective polarizer (hereinafter, referred to as a rear reflective polarizer) 18 provided as a reflection means also serving as an analyzer on the rear side of the liquid crystal element 1. The light reflected by the front-side reflective polarizing plate 10 is internally reflected on the front side of the reflective polarizer (hereinafter, referred to as a front-side reflective polarizer) 10 disposed on the front side of the liquid crystal element 1 to form the front-side reflected polarized light. A λ / 4 phase plate 16 is disposed as a transparent film for re-entering the plate 10, and an absorption polarizing plate 19 is provided as a light absorbing means behind the rear reflection polarizing plate 18.

The liquid crystal element 1 is a simple matrix liquid crystal element having a structure as shown in FIG. 2, and the liquid crystal molecules of the liquid crystal layer are twist-oriented at a twist angle of 180 ° to 270 °.

The twist angle of the liquid crystal molecules of the liquid crystal element 1 is preferably in the range of 200 ° to 250 °. In this embodiment, as shown in FIG. The direction 2a of the liquid crystal molecules is shifted clockwise by approximately 35 ° with respect to the horizontal axis x of the screen when viewed from the front, and the direction 3a of the liquid crystal molecules in the vicinity of the rear substrate 3 is referred to as the horizontal axis x. In contrast, the liquid crystal molecules of the liquid crystal layer 9 of the liquid crystal element 1 are set in a direction deviated counterclockwise by approximately 35 ° when viewed from the front side, and the twist direction of the liquid crystal layer 9 is indicated by a broken line arrow in FIG. 3 to the front substrate 2, and is twisted at a twist angle of approximately 250 ° clockwise as viewed from the front.

The front reflection polarizing plate 10 is provided with the first
Similarly to the reflective polarizing plate 11 used in the sixth to sixth embodiments, the front surface is roughened to form a diffusion surface 10a.
The reflective polarizing plate 10 has its transmission axis 10p set in the liquid crystal molecule alignment direction 2 near the front substrate 2 of the liquid crystal element 1.
a in a direction deviated approximately 135 ° counterclockwise when viewed from the front side (with respect to the horizontal axis x of the screen, approximately 1 ° counterclockwise viewed from the front side)
(Direction shifted by 00 °).

The compensating plate 17 is provided for suppressing display banding peculiar to the STN type liquid crystal display device. The compensating plate 17 is formed of a twisted phase plate.
Hereinafter, the compensating plate 17 is referred to as a torsional phase plate.

In FIG. 9, reference numerals 17a and 17b denote the arrangement directions of molecules on the front and rear surfaces of the torsional phase plate 17, and the torsional directions of the torsional phase plate 17 are indicated by broken arrows in the drawing. Thus, it is twisted counterclockwise as seen from the front side from the rear side to the front side with a twist angle of about 250 °.

That is, the twisted phase plate 17 has a molecular arrangement twisted in the direction opposite to the twist direction of the liquid crystal molecules of the liquid crystal element 1 at substantially the same angle as the twist angle of the liquid crystal molecules of the liquid crystal element 1. .

The torsional phase plate 17 has a retardation substantially equal to Δnd of the liquid crystal element 1. In this embodiment, the value of Δnd of the liquid crystal element 1 and the value of the retardation of the twisted phase plate 17 are about 820 nm.

The torsion phase plate 17 is oriented such that the molecular arrangement direction 19a on the front surface thereof is displaced approximately 55 ° clockwise with respect to the horizontal axis x of the screen when viewed from the front, and the molecular arrangement direction 19a on the rear surface. 17b is arranged in a direction deviated substantially 55 ° counterclockwise from the horizontal axis x when viewed from the front side.

That is, the twisted phase plate 17 is set so that the direction between the molecular arrangement directions 17a and 17b of the front and rear surfaces is set to the direction of the orientation of the liquid crystal molecules in the vicinity of the front substrate 2 and the rear substrate 3 of the liquid crystal element 1. It is arranged substantially orthogonal to the middle direction between 2a and 3a (direction along the horizontal axis x of the screen).

The λ / 4 phase plate 16 disposed in front of the front reflective polarizing plate 10 has a slow axis 16a.
Is approximately 1 counterclockwise with respect to the horizontal axis x of the screen when viewed from the front.
They are arranged in a direction shifted by 45 °. That is,
The slow axis 16a of the λ / 4 phase plate 16 intersects the transmission axis 10p of the front reflective polarizing plate 10 at an angle of approximately 45 °.

On the other hand, the rear-side reflection polarizing plate 18 is a normal reflection-polarization plate whose front surface is not roughened. The rear-side reflection polarization plate 18 has its transmission axis 18p with respect to the horizontal axis x of the screen. At an angle of about 90 °, and the reflection axis 18s is arranged substantially parallel to the horizontal axis x.

An absorption polarizer 19 provided on the rear side of the rear reflective polarizer 18 has its transmission axis 19a substantially parallel to the reflection axis 18s of the rear reflective polarizer 18, and an absorption axis (not shown). Is the transmission axis 18p of the rear reflection polarizing plate 18.
And are arranged substantially orthogonally.

Note that the diffusion layer 12 is formed by the first through
The same as the diffusion layer 12 used in the fourth embodiment, a transparent film having a roughened surface, a transparent film in which scattering particles are dispersed, a lens film in which fine lenses are arrayed on one surface, and the like. Consists of

In this liquid crystal display device, the liquid crystal element 1
The front side of the front reflective polarizing plate 10 disposed in front of
Since the four-phase plate 16 is provided, as in the sixth embodiment shown in FIG. 8, of the two orthogonal polarization components of the external light incident from the front side, the light passes through the front-side reflection polarization plate 10. Of the polarization component to be reflected and the reflected polarization plate of the light reflected by the front-side reflection polarization plate 10, internally reflected by the phase plate 16 and changed in polarization state, and again incident on the reflection polarization plate 10. Both of the polarized light component transmitted through the liquid crystal 10 and the polarized component light can be transmitted through the front-side reflective polarizer 10 and become incident light on the liquid crystal element 1.

In the liquid crystal display device of this embodiment,
The light transmitted through the front-side reflective polarizer 10 is transmitted through the twisted phase plate 17 and enters the liquid crystal element 1, and changes the polarization state by the birefringence of the liquid crystal layer of the liquid crystal element 1 to change the polarization state after the liquid crystal element 1. Out to the side.

The light emitted to the rear side of the liquid crystal element 1 passes through the diffusion layer 12 and is incident on the rear reflective polarizer 18, and of the light, the light is transmitted to the transmission axis 18 p of the rear reflective polarizer 18. The light of the polarized component along the rear reflective polarizer 18 is transmitted through and absorbed by the absorbing polarizer 19, and the light of the polarized component along the reflection axis 18 s of the rear reflective polarizer 18 is The light is reflected by the reflective polarizer 18, and the diffusion layer 12, the liquid crystal element 1, the twisted phase plate 17, and the front reflective polarizer 10 are reflected.
Through the λ / 4 phase plate 16 and exit to the front side.

As described above, in the liquid crystal display device of this embodiment, of the two orthogonal polarization components of the external light incident from the front side, the polarization component light transmitted through the front-side reflection polarizing plate 10 and the front side polarization component The light of the polarization component which is reflected by the reflective polarizer 10, is internally reflected by the phase plate 16, changes the polarization state, and is incident on the reflective polarizer 10 again, and transmits through the reflective polarizer 10. Both can be transmitted through the front-side reflective polarizing plate 10 and enter the liquid crystal element 1, so that external light incident from the front side can be used with high efficiency and a bright screen can be obtained.

Further, in this embodiment, the twisted phase plate is provided as the compensating plate 17 for suppressing the banding of the display peculiar to the STN type liquid crystal display device. And the viewing angle characteristics can be improved to increase the viewing angle.

Further, in this embodiment, the liquid crystal element 1 and the rear reflection polarizing plate 18 disposed as reflection means on the rear side are provided.
Since the light is reflected by the rear-side reflection polarizing plate 18 and is emitted to the front side, the light is diffused by the diffusion layer 12 so that a display with a uniform luminance distribution can be obtained. In addition, it is possible to eliminate the reflection of the outside scene such as the face of the display observer and the background thereof reflected on the rear reflection polarizing plate 12.

Also in this embodiment, the diffusion layer 12
The haze value is preferably about 30 to 32, and by doing so, a display with high front luminance can be obtained. Further, the diffusion layer 12 is more preferably a lens film in which minute lenses are arrayed on one surface, and according to this lens film, higher front luminance can be obtained.

In this embodiment, the diffusion layer 12 is provided between the liquid crystal element 10 and the rear reflection polarizing plate 21.
The front diffusion layer 12 may be provided between the torsional phase plate 17 and the front reflective polarizer 10 disposed on the front side of the liquid crystal element 10, and between the liquid crystal element 10 and the rear reflective polarizer 21. The diffusion layer 12 may be provided both between the torsional phase plate 17 and the front-side reflection polarizing plate 10.

Further, the liquid crystal element 1 and the rear reflection polarizing plate 1
In the case where the diffusion layer 12 is provided between the
May be formed by roughening the front surface of the rear reflection polarizing plate 18.

Further, in this embodiment, an absorption polarizer 19 is provided as a light absorbing means on the rear side of the rear reflective polarizer 18 disposed on the rear side of the liquid crystal element 1. The light absorbing means provided on the rear side of the plate 18 may be a black absorbing film. If a liquid crystal element 1 having no color filter is used, the light absorbing means may be a color film of any color. Further, the light absorbing means may be omitted.

When the light absorbing means is a color film, or when the light absorbing means is omitted, light can also be incident from the rear side of the liquid crystal display device.
In an environment where external light with sufficient brightness can be obtained, reflective display using external light is performed, and when external light with sufficient brightness cannot be obtained, the backlight is turned on and transmissive display using the illumination light is performed. Can be performed.

In the sixth embodiment shown in FIG. 8 and the seventh embodiment shown in FIG. 9, the front surface of the reflective polarizing plate 10 disposed in front of the liquid crystal element 1 is the diffusion surface 10a. Instead, a diffusion layer made of a roughened film, a scattering particle dispersion film, or the like is provided on the front surface (between the reflective polarizing plate 10 and the phase plate 16) of the reflective polarizing plate 10 and reflected by the reflective polarizing plate 10. The diffused light may be diffused by the diffusion layer. In this case, too, the light of one polarization component reflected by the reflective polarizing plate 10 is diffused, and the reflected light is increased, so that the phase plate Although it is made to enter at an incident angle that is internally reflected with respect to 16,
In the sixth and seventh embodiments, the reflection polarizing plate 1 is disposed on the front side of the reflection polarizing plate 10 disposed on the front side of the liquid crystal element 1.
0 is reflected internally by the reflection polarizing plate 1.
Λ / 4 as a transparent film for re-entering
Although the phase plate 16 is disposed, the transparent film disposed on the front side of the reflective polarizing plate 10 is not limited to the λ / 4 phase plate,
For example, it may be optically isotropic.

When the transparent film is optically isotropic, the light reflected by the reflective polarizing plate 10 and internally reflected by the transparent film is reflected by the reflective polarizing plate 10 without substantially changing the polarization state. Again.

However, although the reflection polarizing plate 10 mainly reflects light of a polarization component along the reflection axis 10s,
Since the light of the polarization component along the transmission axis 10p is also reflected to some extent, the light reflected by the reflective polarizing plate 10 includes not only the light of the polarization component along the reflection axis 10s but also the transmission axis 10p. Is included as well.

Therefore, the transparent film is optically isotropic, and the light reflected by the reflective polarizing plate 10 and the light internally reflected by the transparent film hardly changes the polarization state. Incident again,
The light of the polarization component along the transmission axis 10p included in the light passes through the reflective polarizer 10 and enters the liquid crystal element 1.

On the other hand, when the transparent film is not provided on the front side of the reflection polarizing plate 10, the reflection polarizing plate 10
Is not incident on the reflective polarizing plate 10 again, so that the light of the polarized light component along the transmission axis 10p included in the reflected light is wasted.

Therefore, even if the transparent film disposed on the front side of the reflective polarizing plate 10 is optically isotropic,
As compared with the case where the transparent film is not provided on the front side of the reflective polarizing plate 10, the amount of light that enters from the front side, passes through the reflective polarizing plate 10, and enters the liquid crystal element 1 can be increased.

However, in order to allow more incident light from the front side to pass through the reflective polarizing plate 10 and enter the liquid crystal element 1, an optical characteristic for changing the polarization state of the transmitted light is provided on the front side of the reflective polarizing plate 10. It is desirable to dispose a transparent film having the following. In this manner, light reflected by the reflective polarizing plate 10 and internally reflected by the transparent film is converted into a polarized light component (transmitted light) transmitted through the reflective polarizing plate 10. It is possible to make the light enter the reflective polarizer 10 again as light containing more polarization components (along the polarization component along the axis 10p), and make more light enter the liquid crystal element 1.

The transparent film is more preferably the λ / 4 phase plate 16 used in the sixth and seventh embodiments. By using the λ / 4 phase plate 16, the reflection polarizing plate 10 Λ / 4 phase plate 16
Most of the light internally reflected by the reflection polarizing plate 10 is converted into light having a polarization component transmitted through the reflection polarizing plate 10.
Again, the utilization efficiency of external light incident from the front side is further increased, the bright display is made brighter, and light leakage to the front side is almost eliminated, so that a better contrast can be obtained.

[0136]

According to the first liquid crystal display device of the present invention, one of the two orthogonal polarization components of the incident light is reflected on the front side of the liquid crystal element, and the other polarization component is reflected. Since a reflective polarizer for transmitting light is disposed and a reflection means is provided on the rear side of the liquid crystal element, of the incident light from the front side, the light reflected by the reflective polarizer reflects the entire screen. Therefore, a bright screen can be obtained by effectively utilizing the incident light from the front side.

Further, the second liquid crystal display device of the present invention comprises:
On the front side of the liquid crystal element, a reflection polarizing plate that reflects light of one polarization component and transmits light of the other polarization component among two polarization components of the incident light orthogonal to each other is arranged,
On the front side of the reflective polarizing plate, a transparent film for internally reflecting the light reflected by the reflective polarizer and re-entering the reflective polarizer is provided, and a reflecting means is provided on the rear side of the liquid crystal element. Therefore, of the incident light from the front side, the light of the polarization component transmitted through the reflective polarizer, is transmitted through the reflective polarizer and is incident on the liquid crystal element, and is reflected by the reflective polarizer, and the transparent film The light of the polarization component transmitted through the reflective polarizing plate of the light that has been internally reflected by the reflective polarizer and is incident on the reflective polarizer can be transmitted through the reflective polarizer and incident on the liquid crystal element. A bright screen can be obtained by effectively utilizing the incident light from the front side.

In the second liquid crystal display device, it is desirable that the transparent film disposed on the front side of the reflective polarizing plate has optical characteristics for changing the polarization state of transmitted light. Thereby, the light reflected by the reflective polarizing plate and internally reflected by the transparent film is re-incident on the reflective polarizing plate as light containing more polarized light components transmitted through the reflective polarizing plate, and more light is emitted. The light can be incident on the liquid crystal element 1.

The transparent film is more preferably a λ / 4 phase plate which gives a phase difference of １ ／ wavelength between the ordinary light and the extraordinary light of the transmitted light. By using this λ / 4 phase plate,
Most of the light reflected by the reflective polarizer and internally reflected by the λ / 4 phase plate is again incident on the reflective polarizer as light having a polarization component transmitted through the reflective polarizer, and is incident from the front side. To further increase the light use efficiency,
The bright display can be made brighter, light leakage to the front side can be almost eliminated, and a better contrast can be obtained.

The λ / 4 phase plate is preferably arranged so that its slow axis intersects the transmission axis of the reflective polarizer at an angle of approximately 45 °. The effect of using the λ / 4 phase plate can be exhibited most effectively.

In any of the first and second liquid crystal display devices of the present invention, a diffusing means for diffusing the light reflected by the reflective polarizing plate on the front surface of the reflective polarizing plate disposed in front of the liquid crystal element. In this way, in the first liquid crystal display device, glare on the screen due to the reflected light of the external light reflected by the reflective polarizing plate is almost eliminated, and the second liquid crystal display device further comprises: In the liquid crystal display device, the light reflected by the reflective polarizing plate can be more internally reflected by the transparent film and can be incident again on the reflective polarizing plate.

In any of the above liquid crystal display devices, one of the two orthogonal polarization components of the incident light is interposed between the liquid crystal element and the reflection polarizing plate disposed in front of the liquid crystal element. It is preferable that the absorbing polarizer that transmits light and absorbs the light of the other polarization component be disposed with its transmission axis substantially parallel to the transmission axis of the reflective polarizing plate, and by doing so, from the front side The light that has entered and transmitted through the reflective polarizing plate is made to enter the liquid crystal element as linearly polarized light having a high degree of polarization by the absorbing polarizing plate, whereby a display with better contrast can be obtained.

Further, in any of the above liquid crystal display devices, at least one of the space between the liquid crystal element and the reflective polarizer disposed on the front side thereof and the space between the liquid crystal element and the reflection means provided on the rear side thereof. On the other hand, it is preferable to provide a diffusion layer for diffusing transmitted light, and by providing this diffusion layer, light reflected by the reflection means and emitted to the front side is diffused by the diffusion layer, thereby displaying a uniform luminance distribution. Can be obtained, and the reflection of the outside scene such as the face of the display observer and the background thereof reflected on the reflection means can be eliminated.

[Brief description of the drawings]

FIG. 1 is an exploded perspective view of a liquid crystal display device according to a first embodiment of the present invention.

FIG. 2 is an enlarged sectional view of a part of a liquid crystal element used in the liquid crystal display device.

FIG. 3 is an enlarged cross-sectional view of the reflective polarizer used in the liquid crystal display device, in which a part of the reflective polarizer is omitted from hatching.

FIG. 4 is an exploded perspective view of a liquid crystal display device according to a second embodiment of the present invention.

FIG. 5 is an exploded perspective view of a liquid crystal display device according to a third embodiment of the present invention.

FIG. 6 is an exploded perspective view of a liquid crystal display device according to a fourth embodiment of the present invention.

FIG. 7 is an exploded perspective view of a liquid crystal display device according to a fifth embodiment of the present invention.

FIG. 8 is an exploded perspective view of a liquid crystal display device according to a sixth embodiment of the present invention.

FIG. 9 is an exploded perspective view of a liquid crystal display device according to a seventh embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Liquid crystal element 2a ... Liquid crystal molecule orientation direction near a front substrate 3a ... Liquid crystal molecule orientation direction near a rear substrate 3, 4 ... Electrode 6R, 6G, 6B ... Color filter 7, 8 ... Alignment film 9 ... Liquid crystal layer DESCRIPTION OF SYMBOLS 10 ... Reflection polarizing plate 12 ... Diffusion layer 10a ... Diffusion surface 10s ... Reflection axis 10p ... Transmission axis 11 ... Absorptive polarization plate 11a ... Transmission axis 12 ... Diffusion layer 13 ... Compensation plate (phase plate) 14 ... Reflection film (reflection means) 15: Absorbing polarizing plate 15a: Transmission axis 16: λ / 4 phase plate (transparent film) 16a: Slow axis 17: Compensating plate (twisted phase plate) 18: Reflecting polarizing plate (reflecting means) 18s: Reflecting axis 18p: Transmission Axis 19: Absorption polarizing plate

 ────────────────────────────────────────────────── ─── Continuation of front page (72) Inventor Kazuhito Sato 5 Cascade, Hachioji Research Laboratory, 2951 Ishikawacho, Hachioji-shi, Tokyo F-term (reference) 2H049 BA02 BA05 BA07 BB03 BB63 BC22 2H091 FA02Y FA07X FA11X FA14X FA14Z FA31X FA34Z FA41Z FD10 HA10 LA03 LA17

Claims (11)

[Claims] An electrode is provided on each of inner surfaces of a front substrate which is a display observation side and a rear substrate opposed to the front substrate, and liquid crystal molecules are interposed between these substrates by 180 °.
A liquid crystal element provided with a liquid crystal layer twisted at a twist angle of up to 270 °; and a light component of one of two orthogonal polarization components of incident light, which is disposed in front of the liquid crystal element. A liquid crystal display device comprising: a reflective polarizing plate that reflects light and transmits light of the other polarization component; and a reflection unit provided on a rear side of the liquid crystal element. 2. An electrode is provided on each of inner surfaces of a front substrate on a display observation side and a rear substrate facing the front substrate, and liquid crystal molecules are interposed between these substrates by 180 °.
A liquid crystal element provided with a liquid crystal layer twisted at a twist angle of up to 270 °; and a light component of one of two orthogonal polarization components of incident light, which is disposed in front of the liquid crystal element. A reflective polarizer that reflects and transmits light of the other polarization component; and a transparent plate that is disposed on the front side of the reflective polarizer and internally reflects light reflected by the reflective polarizer and reenters the reflective polarizer. A liquid crystal display device comprising: a film; and a reflection unit provided on a rear side of the liquid crystal element. 3. The liquid crystal display device according to claim 2, wherein the transparent film disposed on the front side of the reflective polarizing plate has an optical property for changing a polarization state of transmitted light. 4. The liquid crystal display device according to claim 3, wherein the transparent film is a λ / 4 phase plate that gives a phase difference of １ ／ wavelength between the ordinary light and the extraordinary light of the transmitted light. . 5. The λ / 4 phase plate has a slow axis that is substantially four times the transmission axis of a reflective polarizer disposed in front of the liquid crystal element.
The liquid crystal display device according to claim 4, wherein the liquid crystal display devices are arranged so as to intersect at an angle of 5 °. 6. A diffusing means for diffusing light reflected by the reflective polarizing plate provided on the front surface of the reflective polarizing plate disposed on the front side of the liquid crystal element.
Or the liquid crystal display device according to 2. 7. One of two orthogonally polarized light components of incident light is transmitted between a liquid crystal element and a reflective polarizing plate disposed in front of the liquid crystal element, and the other polarized light component is transmitted. 3. The liquid crystal display device according to claim 1, wherein the absorbing polarizer that absorbs light is disposed with its transmission axis substantially parallel to the transmission axis of the reflective polarizing plate. 8. A diffuser for diffusing transmitted light to at least one of between a liquid crystal element and a reflective polarizer disposed on the front side thereof, and between at least one of said liquid crystal element and reflection means provided on the rear side. 2. The method according to claim 1, wherein a layer is provided.
Or the liquid crystal display device according to 2. 9. The reflecting means provided on the rear side of the liquid crystal element,
3. The liquid crystal display device according to claim 1, wherein the liquid crystal display device is a reflective film. 10. An absorbing polarizer between a liquid crystal element and a reflective film, which transmits one of two orthogonal polarization components of incident light and absorbs the other polarization component. The liquid crystal display device according to claim 9, wherein is disposed. 11. A reflection means provided on the rear side of the liquid crystal element reflects one of two orthogonal polarization components of incident light, and transmits the other polarization component. The liquid crystal display device according to claim 1, wherein the liquid crystal display device is a reflective polarizing plate.