HK1022954B - Liquid crystal display - Google Patents

Description

Liquid crystal display device having a plurality of pixel electrodes

Technical Field

The present invention relates to a liquid crystal display device used as a display panel of various electronic devices such as a timepiece (watch and clock) and a portable information device.

Technical Field

A liquid crystal display panel used as a liquid crystal display device has been used for a wristwatch and a watch with a quartz oscillation circuit, in which time information such as time, minute, and second and calendar information including date, day of the week, month, and year are digitally displayed.

There is also a combination timepiece in which an analog display of time information by hands and a digital display of time information and calendar information by numbers and characters are combined.

Further, there has been proposed an analog timepiece (see, for example, japanese patent laid-open No. s 54-153066) in which various scale patterns are selectively displayed when a dial is formed by a liquid crystal display panel, and hands such as an hour hand, a minute hand, and a second hand are displayed in an analog manner when the dial is formed by a liquid crystal display panel.

In addition to a clock, a small-sized reflection-type liquid crystal display device with a very small power consumption is widely used as a display panel for displaying necessary information (character information or image information) in a portable telephone, a desktop computer, a portable game machine, and other various electronic devices.

A conventional liquid crystal display panel as such a liquid crystal display device is configured such that a liquid crystal cell in which liquid crystal is sealed is sandwiched between 2 transparent substrates each having electrodes on opposing inner surfaces, and an upper polarizer and a lower polarizer are disposed on both sides of the liquid crystal cell. A voltage is applied between electrodes of a pair of substrates of a liquid crystal cell to generate an electric field, thereby changing optical characteristics of the liquid crystal, partially controlling transmission and absorption of light incident on the liquid crystal display panel, and performing predetermined display.

Either one of the upper and lower polarizing plates is a polarizing plate that absorbs linearly polarized light having a vibration plane perpendicular to the easy transmission axis.

In a timepiece using such a conventional liquid crystal display panel, time information or calendar information is displayed by displaying black on a white background in a general normal white mode.

However, if the time information or the calendar information is displayed only in such a manner that black is displayed on a white background, the appearance is not changed, and the user is not interested in the time information or the calendar information. Therefore, in recent years, the consumption of digital display watches has been drastically reduced. In addition, a combination timepiece is not so popular, and an analog display timepiece using a liquid crystal display panel is not yet popular.

Similarly, liquid crystal display panels of other electronic devices are normally configured to display various kinds of information in black on a white background, and although there are panels that can perform white-black inversion display by mode inversion, they are still lacking in variety and lack in interest.

The present invention has been made in view of such a situation, and an object thereof is to provide a liquid crystal display device which can display information in an electronic device such as a timepiece in a bright and easy-to-see manner, and which can change an appearance.

Disclosure of the invention

In order to achieve the above object, the present invention provides a liquid crystal display device configured as follows.

An absorption polarizer for absorbing linearly polarized light having a vibration plane perpendicular to an easy transmission axis is disposed on a viewing side of a liquid crystal cell in which liquid crystal is sealed between 2 transparent substrates each having an electrode on an inner surface facing each other, and a reflection polarizer for reflecting linearly polarized light having a vibration plane perpendicular to the easy transmission axis is disposed on an opposite side to the viewing side. A color filter is disposed on the viewing side of the absorptive polarizer or between the absorptive polarizer and the reflective polarizer.

Further, a light absorbing plate may be disposed on the opposite side of the liquid crystal display panel from the viewing side of the reflective polarizing plate. A light scattering plate may be disposed on the viewing side of the absorption polarizing plate.

Alternatively, a backlight may be disposed on the side opposite to the viewing side of the reflective polarizing plate. In this case, a semi-transmissive plate may be provided between the reflective polarizing plate and the backlight. The semi-transmissive plate may be an absorption polarizer.

In the liquid crystal display panel in which these backlights are arranged, a light scattering plate may be arranged on the viewing side of the absorption-type polarizing plate.

In the above-described various liquid crystal display panels, it is preferable that the easy transmission axis of the absorption polarizer disposed on the viewing side of the liquid crystal cell is parallel to the long axis direction of the viewing side liquid crystal molecules in the liquid crystal layer of the liquid crystal cell, and the easy transmission axis of the reflection polarizer is parallel to or perpendicular to the long axis direction of the viewing side liquid crystal molecules in the liquid crystal layer of the liquid crystal cell.

Alternatively, the easy transmission axis of the absorption polarizer disposed on the viewing side of the liquid crystal cell may be parallel to the long axis direction of the liquid crystal molecules on the viewing side in the liquid crystal layer of the liquid crystal cell, and the easy transmission axis of the reflection polarizer may be parallel to or perpendicular to the long axis direction of the liquid crystal molecules on the side opposite to the viewing side in the liquid crystal layer of the liquid crystal cell. The easy transmission axis of the absorption polarizer disposed on the viewing side of the liquid crystal cell is perpendicular to the long axis direction of the liquid crystal molecules on the viewing side in the liquid crystal layer of the liquid crystal cell, and the easy transmission axis of the reflection polarizer is parallel to or perpendicular to the long axis direction of the liquid crystal molecules on the opposite side to the viewing side in the liquid crystal layer of the liquid crystal cell.

(these conditions are required particularly in the case of using a twisted nematic liquid crystal layer having a twist angle of 90 ℃ in a liquid crystal cell.)

As the color filter of the liquid crystal display panel, the following color filter can be used.

1) A selectively transmissive color filter that substantially transmits only light of a particular wavelength;

2) a color polarizing plate in which linearly polarized light having a vibration plane perpendicular to the easy transmission axis transmits only light of a specific wavelength and absorbs light of other wavelengths, and linearly polarized light having a vibration plane parallel to the easy transmission axis transmits all the light;

3) and a dielectric multilayer film that reflects light of a specific wavelength among incident lights and transmits light of other wavelengths.

In the case of using a selective transmission type color filter, a plurality of selective transmission type color filters having different specific wavelengths of the transmitted light may be arranged in a planar manner.

Further, a multicolor metallic tone color display by additive color mixing can be performed by repeatedly and regularly arranging 3-color selective transmission color filters having specific wavelengths of red, green and blue light, respectively, in a fixed order.

Further, a multicolor metallic tone color display by subtractive color mixing may be performed by repeatedly and regularly arranging 3-color selective transmission filters having specific wavelengths in the wavelength regions of cyan, magenta and yellow in a fixed order.

As the liquid crystal layer of the liquid crystal cell, any of a twisted nematic liquid crystal layer, a super twisted nematic liquid crystal layer, or a guest-host liquid crystal layer may be used.

The color filter of the liquid crystal display panel may be disposed on the viewing side of the absorption polarizer, between the absorption polarizer and the liquid crystal cell, or between the liquid crystal cell and the reflective polarizer. Alternatively, the color filter may be provided between a transparent substrate constituting the liquid crystal cell and the liquid crystal layer.

The liquid crystal display device of the present invention changes incident light from a viewing side into linearly polarized light by means of an absorption type polarizing plate, and changes the linearly polarized light into a twisted portion and an untwisted portion when the linearly polarized light passes through the liquid crystal cells in a portion to which a voltage has been applied and a portion to which no voltage has been applied between the liquid crystal cells of the liquid crystal display panel.

Further, since the color filter is provided in the light path, the color is changed. Therefore, the reflected portion is in a bright and colored metallic tone or mirror-glossy display state, and the portion of the reflective polarizing plate through which the incident light passes is in its ground color (the color of the components inside the timepiece, or in the case where a light absorbing plate or a semi-transmissive plate is provided, another arbitrary color such as black or white) so that various information can be brightly displayed in color by virtue of the contrast.

Therefore, a liquid crystal display device for producing a digital display timepiece and other electronic devices with a variety of appearance images can be provided.

Further, if the light scattering plate is disposed on the viewing side of the absorption polarizer of the liquid crystal display panel, the specular reflection light generated by the reflection polarizer is scattered, so that the display of the colored metallic tone or specular gloss becomes a soft tone and is easy to view, and the viewing angle can be widened.

When the backlight is provided on the viewing side of the reflective polarizing plate, even in a dark environment such as at night, by emitting light from the backlight, half of the light incident on the reflective polarizing plate is transmitted through the reflective polarizing plate, and is changed into linearly polarized light, and then the linearly polarized light is incident on the liquid crystal cell. Depending on whether or not a voltage is applied between the electrodes of the liquid crystal cell, the linearly polarized light becomes a twisted portion and an untwisted portion, and various information can be vividly displayed in color by the light and shade between the portion transmitting through the absorption type polarizing plate and the portion absorbed there and the colorization by the color filter.

Brief description of the drawings

Fig. 1 is a schematic cross-sectional view showing a configuration of example 1 of a liquid crystal display device of the present invention, and fig. 2 and 3 are schematic cross-sectional views showing modifications thereof, respectively.

Fig. 4 is a schematic cross-sectional view showing the configuration of the liquid crystal cell of fig. 1, with the middle portion being cut away, and fig. 5 to 7 are cross-sectional views similar to fig. 4, each showing a different example of a liquid crystal cell provided with a color filter.

Fig. 8 is a sectional view schematically showing the configuration of a liquid crystal display device using the liquid crystal cell shown in any one of fig. 5 to 7.

Fig. 9 and 10 are explanatory diagrams for explaining the principle of color display realized by the liquid crystal display device of fig. 1.

Fig. 11 to 17 are schematic sectional views showing the configurations of embodiments 2 to 8 of the liquid crystal display device of the present invention, respectively.

Fig. 18 and 19 are explanatory diagrams for explaining the structure of example 9 of the liquid crystal display device of the present invention and the principle of color display realized by the liquid crystal display device.

Fig. 20 and 21 are explanatory views for explaining the structure of example 10 of the liquid crystal display device of the present invention and the principle of color display realized by the liquid crystal display device.

PREFERRED EMBODIMENTS

Hereinafter, preferred embodiments of the liquid crystal display device according to the present invention will be described with reference to the drawings.

[ example 1]

First, embodiment 1 of a liquid crystal display panel according to the present invention and a modification thereof will be described with reference to fig. 1 to 10. These figures show the thickness and spacing of the various components in greatly enlarged scale.

Fig. 1 is a schematic cross-sectional view of the structure of the liquid crystal display panel 10, and fig. 4 is a schematic cross-sectional view of the structure of the liquid crystal cell 12, which is cut at the middle portion.

As shown in fig. 1, the liquid crystal display panel 10 includes a liquid crystal cell 12, an absorption polarizer 14 disposed on a viewing side (upper side in the figure), a reflection polarizer 16 disposed on a side (lower side in the figure) opposite to the viewing side of the liquid crystal cell 12, and a color filter 18 disposed between the absorption polarizer 14 and the liquid crystal cell 12.

As shown in fig. 4, the liquid crystal cell 12 is formed by bonding a pair of substrates 1 and 2 each made of a transparent insulating material such as glass, providing a sealing material 4 around the substrates, and sealing and sandwiching a liquid crystal layer 3 between the substrates. Transparent electrodes 5 and 6 made of Indium Tin Oxide (ITO) or the like are formed on the inner surfaces of the pair of substrates 1 and 2 facing each other, and at least one of the electrodes is formed in a pattern (generally, a 7-segment character pattern in the case of displaying numerals) necessary for displaying time information or calendar information.

The liquid crystal layer 3 is composed of Twisted Nematic (TN) liquid crystal having a twist angle of 90 degrees. The liquid crystal molecules are aligned in a predetermined direction by applying alignment treatment to the liquid crystal layer 3 side of the substrates 1 and 2 and the electrodes 5 and 6.

The absorption-type polarizing plate 14 disposed on the viewing side of the liquid crystal cell 12 is a thin plate-like member that transmits linearly polarized light having an oscillation plane parallel to the easy transmission axis and absorbs linearly polarized light having an oscillation plane in a direction perpendicular to the easy transmission axis.

The reflective polarizing plate 16 provided on the side opposite to the viewing side of the liquid crystal cell 12 is a thin plate-like member that transmits linearly polarized light having a plane of vibration parallel to the easy transmission axis and reflects linearly polarized light having a plane of vibration perpendicular to the easy transmission axis. As the reflective polarizing plate 16, for example, an optical film DBEF (trade name) sold by sumitomo 3M co.

The easy transmission axis of the absorption polarizer 14 and the long axis direction of the liquid crystal molecules on the viewing side in the liquid crystal layer 3 of the liquid crystal cell 12 are arranged in parallel to each other.

The easy transmission axis of the reflective polarizer 16 and the long axis direction of the liquid crystal molecules on the side opposite to the viewing side in the liquid crystal layer 3 of the liquid crystal cell 12 are also arranged parallel to each other.

The easy transmission axis of the absorption type polarizer 14 is perpendicular to the easy transmission axis of the reflection type polarizer 16.

In fig. 1, the direction of the stripes in the absorption polarizer 14 and the reflection polarizer 16 indicates the direction of the easy transmission axis, the horizontal stripes in the absorption polarizer 14 indicate the direction parallel to the paper surface, and the vertical stripes in the reflection polarizer 16 indicate the direction perpendicular to the paper surface.

The color filter 18 disposed between the absorption polarizing plate 14 and the liquid crystal cell 12 is a selective transmission type color filter (also called an absorption type color filter) that substantially transmits only light of a specific wavelength and absorbs light of other wavelengths. Therefore, the light transmitted through the color filter is colored to a specific color.

As the selective transmission type color filter, for example, a pigment dispersion coating film in which a pigment is dispersed and mixed in an organic resin is used. Since the pigment dispersion coating film can be formed by a coating method or a printing method, it can be applied to one surface of an existing constituent member (in the example shown in fig. 1, the surface opposite to the viewing side of the absorption polarizer 14 or the surface outside the substrate 1 on the viewing side of the liquid crystal cell 12) without adding a new constituent member. Light incident on the pigment dispersion coating film transmits only light of a specific wavelength, and light of other wavelengths is absorbed.

The color filter 18 is not limited to the position shown in fig. 1, and may be disposed at any position on the viewing side of the reflective polarizer 16 constituting the liquid crystal display panel 10. Therefore, as shown in fig. 2, the liquid crystal cell may be disposed on the viewing side (outside) of the absorption polarizer 14, or as shown in fig. 3, the liquid crystal cell may be disposed between the liquid crystal cell 12 and the reflection polarizer 16.

Alternatively, as shown in fig. 5 or 6, the liquid crystal cell 12 may be a color filter-containing liquid crystal cell 12CF, and as shown in fig. 8, the liquid crystal display panel 10 may be configured by arranging only the absorption polarizer 14 and the reflection polarizer 16 on both sides of the color filter-containing liquid crystal cell 12 CF.

In this case, as shown in fig. 5, the color filter 18 may be formed by applying a pigment dispersion coating film to the inner surface of the substrate 1 on the viewing side of the liquid crystal cell 12CF, or as shown in fig. 8, the color filter 18 may be formed by applying a pigment dispersion coating film to the inner surface of the substrate 2 on the side opposite to the viewing side of the liquid crystal cell 12 CF.

Transparent electrodes 5 and 6 are formed on the surfaces of the color filters 18 that contact the liquid crystal layer 3. However, the color filter may be formed over the entire surface in contact with the liquid crystal layer 3 of the substrate 1 on which the electrode 5 is formed or over the entire surface in contact with the liquid crystal layer 3 of the substrate 2 on which the electrode 6 is formed.

When a selective transmission type color filter is used as the color filter 18, a plurality of types of selective transmission type color filters having different specific wavelengths of transmitted light may be arranged in a planar manner.

A multicolor metallic tone color display by additive color mixing can be performed by repeatedly and regularly arranging 3 selective transmission color filters having specific wavelengths of red, green and blue light, respectively, in a predetermined order.

For example, as shown in fig. 7, a liquid crystal cell 12CF having a built-in color filter is constituted such that a red pigment dispersion coating (R) having a specific wavelength of 600nm to 700nm, a green pigment dispersion coating (G) having a specific wavelength of 500nm to 600nm, and a blue pigment dispersion coating (B) having a specific wavelength of 400nm to 500nm are regularly arranged as a color filter 18 on the inner surface of a transparent substrate 1 in order of R, G, B. On each pigment dispersion coating film, an independent electrode unit constituting the electrode 5 is formed. Additive color mixing can be performed by configuring 1 pixel with the pigment dispersion coating films R, G, B of the 3 colors and controlling the ON/OFF (ON/OFF) of the voltage between the electrode unit and the other common electrode 6 ON each pigment dispersion coating film.

Although the case where the color filter 18 formed of the pigment dispersion coating films R, G, B of the 3 colors is provided on the inner surface of the substrate 1 on the viewing side of the liquid crystal cell 12 is exemplified, it may be provided on the inner surface of the substrate 2 on the side opposite to the viewing side. In this case, the electrodes 6 formed thereon are formed as electrode units corresponding to the respective pigment dispersion coatings R, G, B, and the electrode 5 on the substrate 1 side is formed as a common electrode.

Further, although the color filter 18 composed of the above-described 3-color pigment dispersion coating film R, G, B may be formed on the outer surface (the surface opposite to the liquid crystal layer 3) of either of the substrates 1 and 2, when a plurality of pigment dispersion coating films having different specific wavelengths are aligned in a planar manner, subtractive color mixing is caused with respect to light incident obliquely by the thickness of the substrate 1 or the substrate 2, and the color purity and the luminance are lowered, which is not preferable.

Alternatively, the color filter 18 may be a selective transmission type color filter of 3 colors (C, M, Y) in which the above-mentioned wavelengths of transmitted light are in the wavelength regions of cyan (400nm to 600nm), magenta (400nm to 500nm and 600nm to 700nm), and yellow (500 to 700nm), respectively, and may be arranged in a regular array in a predetermined order. In this case, multicolor metallic tone color display by subtractive color mixing is possible.

Next, the principle of color display by the liquid crystal display panel shown in fig. 1 will be described with reference to fig. 9 and 10.

In these figures, as described in fig. 1, the horizontal stripes in the absorption polarizer 14 and the vertical stripes in the reflection polarizer 16 respectively indicate that the easy transmission axis is parallel to the paper surface and perpendicular to the paper surface, the long solid line with an arrow at the tip end indicates light, the short solid line with an arrow at both ends indicates the direction of the vibration plane of linearly polarized light after passing through each component, the horizontal direction indicates parallel to the paper surface, and the vertical direction indicates perpendicular to the paper surface.

As described above, the liquid crystal layer 3 of the liquid crystal cell 12 is defined to be composed of TN liquid crystal having a twist angle of 90 °. Color filter 18 is defined as a selective transmission type color filter which transmits only yellow light and absorbs light other than yellow light.

Fig. 9 shows a background portion where no voltage (called OFF state) is applied between the electrodes 5, 6 of the liquid crystal cell 12, and in this portion, the vibration plane of the linearly polarized light transmitted through the liquid crystal cell 12 is twisted (phase-modulated) by 90 ° due to the twisting function of the liquid crystal layer 3 (fig. 6).

Fig. 10 shows a display portion of characters or the like to which a voltage (called ON state) has been applied between the electrodes 5, 6 of the liquid crystal cell 12, in which the liquid crystal layer 3 of the liquid crystal cell 12 does not have a function of twisting because of standing up of liquid crystal molecules, and the direction of the plane of vibration of the incident linearly polarized light is transmitted without being twisted (phase modulation) as it is.

Of the light incident on the liquid crystal display panel 10 from the viewing side (upper side in the drawing), half of the light is absorbed by the absorption polarizer 14, and the remaining half is transmitted through the absorption polarizer 14 and then becomes linearly polarized light having a vibration plane in a direction parallel to the paper surface and is incident on the color filter 18.

However, light other than yellow is completely absorbed by the color filter 18 regardless of the state of the liquid crystal cell 12. The yellow light is transmitted through the color filter 8 and then enters the liquid crystal cell 12.

When the liquid crystal cell is in the OFF state shown in fig. 9, the direction of the vibration plane of the yellow linearly polarized light is twisted by 90 ° while passing through the liquid crystal cell 12, and the yellow linearly polarized light is incident on the reflective polarizer 16 in a direction perpendicular to the paper surface. Therefore, the direction of the vibration plane of the yellow linearly polarized light is the same as the direction of the easy transmission axis of the reflective polarizer 16, and as a result, the light passes through the reflective polarizer 16, and the ground color (the color of the internal components if the timepiece is mounted) appears dark when viewed from the viewer side.

ON the other hand, when the liquid crystal cell 12 is in the ON state shown in fig. 10, the yellow linearly polarized light is transmitted through the liquid crystal cell 12 without being distorted, and the direction of the vibration plane is incident ON the reflective polarizer 16 while maintaining the original parallel direction. Therefore, the yellow linearly polarized light is specularly reflected by the reflective polarizer 16 because the direction of the vibration plane is perpendicular to the direction of the easy transmission axis of the reflective polarizer 16. Since the reflected light is emitted to the viewing side through a path opposite to the incident time, a yellow metallic tone appears brightly. This is the same effect as placing the yellow filter on top of the mirror.

Therefore, if a voltage is applied between the electrodes of the liquid crystal cell 12 only to a portion where characters of information are displayed, the result is that the characters are brightly displayed with a yellow metallic tone (nearly gold color) in a dark background that is transparent to the inside.

As described above, in the liquid crystal display device of the present invention, almost all of the light made colored by entering the liquid crystal display panel 10 is reflected in the region where information characters or the like are displayed, and thus the colored metallic tone can be brightly displayed.

On the other hand, in the background region for displaying information, since light incident on the liquid crystal display panel 10 is transmitted through the reflective polarizer 16, the light is consequently transmitted through the side opposite to the viewing side of the reflective polarizer 16. Therefore, the entire screen is displayed so as to be raised in a colored metallic tone, such as characters.

Further, if the easy transmission axis of the reflective polarizer 16 is arranged to be perpendicular to the long axis direction of the liquid crystal molecules on the side opposite to the viewing side of the liquid crystal layer 3, the easy transmission axis of the absorptive polarizer 14 is parallel to the easy transmission axis of the reflective polarizer 16, and therefore the display state in the above example is reversed, and characters and the like can be displayed in a state of being able to transmit through the inside in a background of yellow metal tone.

When filters of different transmission colors are used as the color filter 18, a display color of a metal tint or a background color of an arbitrary color can be obtained.

Therefore, according to the present invention, a liquid crystal display device which is more interesting and has a varied appearance can be provided as compared with a conventional liquid crystal display device which displays various information by displaying black on a white background.

Further, such a liquid crystal display panel may be a dot-matrix liquid crystal display panel which can display arbitrary characters or graphics, or may be formed of various patterns of electrodes of a liquid crystal cell so that desired graphics can be selectively displayed.

As shown in fig. 2, 3, and 5 to 8, even in the liquid crystal display panel in which the color filters 18 are respectively located at different positions, the positions at which the color filters 18 colorize only the light incident on the liquid crystal display panel are different, and the above-described color display function is the same.

As shown in fig. 7, when the color filter 18 is constituted by 1 pixel using the 3-color pigment dispersion coating R, G, B, it is possible to perform display by specular reflection light obtained by additive color mixing of 3 colors of red, green, and blue for each pixel, and to perform color display of arbitrary characters and figures with a multicolor metallic tone.

Although the above description has been made of the case where the liquid crystal layer 3 enclosed in the liquid crystal cell 12 is a Twisted Nematic (TN) liquid crystal having a twist angle of 90 °, a TN liquid crystal having a twist angle of less than 90 °, a Super Twisted Nematic (STN) liquid crystal having a twist angle of 180 degrees to 270 degrees, a guest host liquid crystal, or the like may be used.

If a super twisted nematic liquid crystal is used, the steepness of the liquid crystal layer can be improved and the contrast can be increased.

When the liquid crystal cell has a function of phase-modulating the linearly polarized light transmitted through the liquid crystal layer 3 to twist the direction of the vibration plane, the easy transmission axes of the absorption polarizer 14 and the reflection polarizer 16 disposed on both sides of the liquid crystal cell 12 are disposed parallel to each other or intersect at the same angle as the twist angle (the easy transmission axes are perpendicular when the twist angle is 90 degrees).

The guest-host liquid crystal is a mixed liquid crystal in which a 2-color dye is dissolved as a solute in a liquid crystal as a solvent. When the alignment state of the liquid crystal molecules is changed by an electric field, the alignment of the 2-color dye can be controlled according to the movement of the liquid crystal molecules, and modulated display can be performed on the absorption of light incident from a certain direction.

When the guest-host liquid crystal is sealed in the liquid crystal cell 12 of the liquid crystal display panel 10, the region where information such as characters is displayed can be colored in a metallic tone display state, and the background portion can also be colored.

Here, by selecting the specific wavelength transmitted by the color filter 18 and the absorption wavelength of the 2-color dye dissolved in the guest-host liquid crystal, the combination of colors between the region for displaying characters and the like and the background region thereof can be freely configured.

In the above description, the transmissive color filter is selected as the color filter, but a dielectric multilayer film may be used.

The dielectric multilayer film is a multilayer film in which dielectrics having different refractive indexes are laminated, and reflects light of a specific wavelength and transmits light of other wavelengths in incident light.

Therefore, when the color filter 18 made of the dielectric multilayer film is disposed on the viewing side of the absorption polarizer 14, only light of a specific wavelength among light incident on the liquid crystal display panel is reflected by the color filter 18 of the dielectric multilayer film, and light other than the specific wavelength is incident on the absorption polarizer 14. Linearly polarized light parallel to the easy transmission axis of the absorption polarizer 14 enters the liquid crystal cell 12. In the background portion of the display, linearly polarized light of light other than the specific wavelength is subjected to 90-degree phase modulation in the liquid crystal cell 12, and is also transmitted through the reflective polarizer 16. On the other hand, in a display portion of characters or the like, since a voltage is applied between electrodes of the liquid crystal cell 12, linearly polarized light of light other than light of a specific wavelength is transmitted through the liquid crystal cell 12 without phase modulation, and is specularly reflected by the reflective polarizer 16 to return to the viewing side.

Therefore, almost all of the incident light is reflected in the region where information such as characters is displayed, and the light becomes bright metallic tone. On the other hand, in the background portion of the display, since only light of a specific wavelength is reflected by the color filter 18 of the dielectric multilayer film, the background can be colored, and a bright metallic tone display is performed therein.

In the case of using the dielectric multilayer film, there is almost no loss of light in its constitution. The specific wavelength to be reflected can be freely set by changing the combination of the refractive indices of the dielectric layers.

Further, a color polarizing plate may be used as the color filter 18, and an embodiment thereof will be described in detail later.

In addition, a reflective color filter which transmits only light of a specific wavelength and reflects light of other wavelengths, a fluorescent color filter which has a function of converting the wavelength of incident light, or the like can be used.

[ example 2]

Next, embodiment 2 of the liquid crystal display device of the present invention will be described with reference to fig. 11. Fig. 11 is a schematic cross-sectional view showing the structure of the liquid crystal display panel, and the same portions as those in fig. 1 to 10 are given the same reference numerals and their description is omitted.

In the structure of this liquid crystal display panel, the light absorbing plate 13 is simply disposed on the side opposite to the viewing side of the reflective polarizer 16 (the lower side in the figure), unlike the structure shown in fig. 1. The light absorbing plate 13 may be a black light absorbing film, an absorptive polarizer, an absorptive color filter, or the like. When the absorption-type polarizer is used, the easy transmission axis is arranged to be perpendicular to the easy transmission axis of the reflection-type polarizer 16.

When the light absorbing plate 13 is disposed on the side opposite to the viewing side of the reflective polarizing plate 16, the light transmitted through the reflective polarizing plate 16 can be absorbed by the light absorbing plate 13, and the background portion for displaying information can be displayed in black or dark, and characters and the like can be clearly displayed in a colored metallic tone.

The contrast of the display will be improved. In the case of the reverse display, various information such as time information and calendar information may be displayed with good contrast by black or nearly black characters in a background of bright metallic tone.

Other functions and applications of various modifications are the same as those of embodiment 1, and therefore, descriptions thereof are omitted.

[ example 3]

Next, embodiment 3 of the liquid crystal display device of the present invention will be described with reference to fig. 12. Fig. 12 is a schematic cross-sectional view showing a configuration of a liquid crystal display panel as a liquid crystal display device, and the same portions as those in fig. 1 to 10 are given the same reference numerals and description thereof is omitted.

The liquid crystal display panel is different from the configuration shown in fig. 1 only in that the light diffusion plate 15 is disposed on the viewing side (upper side in the drawing) of the absorption polarizer 14.

The light diffusion plate 15 is formed by coating a mixture of silica particles or acrylic porous glass beads or calcium powder as silicon oxide mixed in a binder on a film-shaped substrate.

When the light diffusion plate 15 is disposed on the viewing side of the absorption polarizer 14, light that is specularly reflected from the reflection polarizer 16 and emitted to the viewing side can be diffusely reflected by the light diffusion plate 15. With this, it is possible to make the color tone of the colored metal such as the display time information and the calendar information soft and easy to view, and to widen the viewing angle.

Although the description has been given of the example in which the light diffusion plate 15 is disposed on the viewing side of the absorption polarizer 14, the light diffusion plate 15 may be disposed between the absorption polarizer 14 and the liquid crystal cell 12, or between the liquid crystal cell 12 and the reflective polarizer 16.

Other functions and applications of various modifications are the same as those in embodiment 1, and therefore, descriptions thereof are omitted.

[ example 4]

Next, embodiment 4 of the liquid crystal display device of the present invention will be described with reference to fig. 13. Fig. 13 is a schematic cross-sectional view showing a configuration of a liquid crystal display panel as a liquid crystal display device, and the same portions as those in fig. 1 to 12 are given the same reference numerals and description thereof is omitted.

In the structure of this liquid crystal display panel, the difference from the structure shown in fig. 1 is that the light absorbing plate 13 is disposed on the side opposite to the viewing side of the reflective polarizer 16, and the light scattering plate 15 is disposed on the viewing side of the absorptive polarizer 14.

This structure is provided with both the light absorbing plate 13 of the liquid crystal display panel of fig. 12 and the light scattering plate 15 of the liquid crystal display panel of fig. 13, and both the functions and effects can be obtained.

That is, the contrast between the background portion and the character portion of the display information can be increased, and the color metallic tone displayed can be changed to a soft tone to be easily viewed, and the viewing angle can be widened.

Other functions and applications of various modifications are the same as those in embodiment 1, and therefore, descriptions thereof are omitted.

[ example 5]

Next, example 5 of the liquid crystal display device of the present invention will be described with reference to fig. 14. Fig. 14 is a schematic cross-sectional view showing a configuration of a liquid crystal display panel as a liquid crystal display device, and the same portions as those in fig. 1 to 10 are given the same reference numerals and their description is omitted.

In the structure of this liquid crystal display panel, the backlight 17 is arranged on the side opposite to the viewing side of the reflective polarizer 16 (the lower side in the figure), which is different from the structure shown in fig. 1.

The backlight 17 uses a light source such as an electroluminescent device, a Light Emitting Diode (LED) array, or a cold cathode tube or a hot cathode tube.

When the backlight 17 is disposed on the side opposite to the viewing side of the reflective polarizer 16, half of the light incident on the reflective polarizer 16 from the backlight 17 is transmitted, becomes linearly polarized light, and enters the liquid crystal cell 12. In the background portion for displaying time information, calendar information, and the like, only light having a specific wavelength is transmitted through the color filter by performing 90-degree phase modulation when the linearly polarized light is transmitted through the liquid crystal cell 12, and the light is colored and then transmitted through the absorption type polarizing plate 14 and is emitted to the viewer side.

In a portion where characters of various information such as time information and calendar information are displayed, since a power source is applied between electrodes of the liquid crystal cell 12, linearly polarized light generated by a backlight incident on the liquid crystal cell 12 is transmitted without being phase-modulated by the liquid crystal layer 3, and the vibration plane thereof is perpendicular to the easy transmission axis of the absorption polarizer 14 and absorbed by the absorption polarizer 14.

Therefore, even in a place where there is no external light or little external light, various information such as time information and calendar information can be displayed in black or dark in a bright background portion formed by colored transmitted light by emitting a backlight.

Other functions and applications of various modifications are the same as those in embodiment 1, and therefore, descriptions thereof are omitted.

[ example 6]

Next, example 6 of the liquid crystal display device of the present invention will be described with reference to fig. 15. Fig. 15 is a schematic cross-sectional view showing a configuration of a liquid crystal display panel as a liquid crystal display device, and the same portions as those in fig. 1 to 14 are given the same reference numerals and their description is omitted.

The liquid crystal display panel is different from the configuration shown in fig. 14 only in that the semi-transmissive plate 19 is disposed between the reflective polarizer 16 and the backlight 17.

In this example, an absorption-type polarizer is used as the semi-transmissive plate 19, and the angle formed by the easy transmission axis and the easy transmission axis of the reflective polarizer 16 is set to 75 degrees.

When the semi-transmissive plate 19 is disposed between the reflective polarizing plate 16 and the backlight 24, when the backlight 17 does not emit light, half of the light transmitted through the reflective polarizing plate 16 can be absorbed by the semi-transmissive plate 19, and the display of the background portion becomes dark, so that the contrast of the display of time information, calendar information, and the like can be improved.

On the other hand, when the ambient external light is reduced and the backlight 17 emits light, the light transmitted through the semi-transmissive plate 19 brightens the background portion, and the characters such as the display time information and the calendar information are displayed in black and dark.

Therefore, the contrast of the display can be improved even when the backlight 17 emits no light or even when the backlight emits light.

Other functions and applications of various modifications are the same as those in embodiments 1 and 5, and therefore, descriptions thereof are omitted.

[ example 7]

Next, example 7 of the liquid crystal display device of the present invention will be described with reference to fig. 16. Fig. 16 is a schematic cross-sectional view showing the configuration of a liquid crystal display panel as a liquid crystal display device thereof, and the same portions as those in fig. 1 to 14 are given the same reference numerals and the description thereof is omitted.

In the structure of this liquid crystal display panel, the difference from the structure shown in fig. 14 is that the light diffusion plate 15 is disposed only on the viewing side of the absorption polarizer 14.

When the light scattering plate 15 is disposed on the viewing side of the absorption polarizer 14, the light emitted to the viewing side after being specularly reflected by the absorption polarizer 14 can be diffusely reflected by the light scattering plate 15, so that the viewing angle can be widened while the colorized metallic tone of the characters or the like of the display information is changed to a soft tone to facilitate the viewing.

Other functions and applications of various modifications are the same as those in embodiments 1 and 5, and therefore, descriptions thereof are omitted.

[ example 8]

Next, example 8 of the liquid crystal display device of the present invention will be described with reference to fig. 17. Fig. 17 is a schematic cross-sectional view showing the structure of the liquid crystal display panel, and the same portions as those in fig. 1 to 16 are given the same reference numerals and the description thereof will be omitted.

In the structure of this liquid crystal display panel, the difference from the structure shown in fig. 15 is that the light diffusion plate 15 is disposed only on the viewing side of the absorption polarizer 14.

When the light scattering plate 15 is disposed on the viewing side of the absorption polarizer 14, the light emitted to the viewing side after being specularly reflected by the absorption polarizer 14 can be diffusely reflected by the light scattering plate 15, so that the viewing angle can be widened while the colorized metallic tone of the characters or the like of the display information is changed to a soft tone to facilitate the viewing.

Other functions and applications of various modifications are the same as those in embodiments 1 and 6, and therefore, descriptions thereof are omitted.

[ example 9]

Next, example 9 of the liquid crystal display device of the present invention will be described with reference to fig. 18 and 19. Fig. 18 and 19 are schematic cross-sectional views for explaining the structure of a liquid crystal display panel and the principle of color display, which are liquid crystal display devices, and the same parts as those in fig. 1 to 11 are assigned the same reference numerals and the explanation thereof is omitted. The directions of the stripes in the polarizing plates and the solid lines with arrows in fig. 18 and 19 are the same as those described with reference to fig. 9 and 10.

The structure of the liquid crystal display panel differs from the structure shown in fig. 11 only in that: as the color filter, a color polarizing plate 28 is disposed between the absorption polarizing plate 14 and the liquid crystal cell 12 instead of the transmission type color filter 18.

The color polarizing plate 28 transmits only light of a specific wavelength among linearly polarized light having a vibration plane perpendicular to the easy transmission axis and absorbs light of other wavelengths. And the light transmitting member transmits light of a specific wavelength and other wavelengths to linearly polarized light having a vibration plane parallel to the easy transmission axis.

Here, the color polarizing plate 28 is disposed such that its easy transmission axis is perpendicular to the easy transmission axis of the absorption polarizing plate 14.

In this embodiment, the arrangement is made in the order of the absorption polarizer 14, the color polarizer 28, and the liquid crystal cell 12.

Therefore, since the light transmitted through the absorption polarizer 14 is linearly polarized light having a vibration plane perpendicular to the easy transmission axis of the color polarizer 28, only light having a specific wavelength transmits through the color polarizer 28. The other wavelengths of light that have passed through the transmissive polarizer 14 are absorbed by the color polarizer 28. In the illustrated example, the specific wavelength is the wavelength of yellow light.

Fig. 18 shows a path of light other than yellow in light incident on the liquid crystal display panel from the viewing side, and fig. 19 shows a path of light of yellow. The left half of these figures shows an OFF state in which no voltage is applied between the electrodes of the liquid crystal cell 12, and the right half shows an ON state in which a voltage is applied between the electrodes of the liquid crystal cell 12.

As shown in fig. 18, light other than yellow incident on the liquid crystal display panel from the viewing side is transmitted through the absorption polarizer 14, becomes linearly polarized light having a vibration plane parallel to the easy transmission axis thereof (parallel to the paper surface), and enters the color polarizer 28, but the vibration plane is perpendicular to the easy transmission axis of the color polarizer 28, and is totally absorbed by the color polarizer 28.

Therefore, the display is not affected regardless of the ON/OFF state of the liquid crystal cell 12.

As shown in fig. 19, the yellow light incident on the liquid crystal display panel from the viewing side is transmitted through the absorption polarizer 14 and becomes linearly polarized light having a vibration plane parallel to the easy transmission axis thereof, and the light incident on the color polarizer 28 is the same as the light other than yellow light, but the direction of the vibration plane of the yellow linearly polarized light is perpendicular to the easy transmission axis of the color polarizer 28 and can be transmitted through the color polarizer 28, and thus the yellow linearly polarized light is incident on the liquid crystal cell 12 as it is.

In this way, in the background portion where the liquid crystal cell 12 is in the OFF state, the yellow linearly polarized light incident on the liquid crystal cell 12 undergoes 90-degree phase modulation when passing through the liquid crystal cell 12, and the direction of the vibration plane thereof is changed to a direction parallel to the easy transmission axis of the reflective polarizer 16 (perpendicular to the paper surface), and is absorbed by the light absorbing plate 13 disposed on the rear side thereof after passing through the liquid crystal cell 12. And thus appears black or dark as viewed from the viewing side.

ON the other hand, in a display portion of characters or the like in which the liquid crystal cell 12 is turned ON, yellow linearly polarized light that has entered the liquid crystal cell 12 is transmitted through the liquid crystal cell 12 without phase modulation and enters the reflective polarizer 16. Therefore, since the direction of the vibration plane of the yellow linearly polarized light is perpendicular to the easy transmission axis of the reflective polarizer 16, the yellow linearly polarized light is specularly reflected by the reflective polarizer 16 and is emitted to the viewing side through an opposite path.

Therefore, in the region where information characters or the like are displayed, almost all of the yellow light incident on the liquid crystal cell 12 is reflected, and the light is brightly displayed in a colored (yellow) metallic tone in a black or dark background.

Therefore, the liquid crystal display panel is used as a display device of an electronic apparatus, and compared with a conventional electronic apparatus which displays various information such as time information and calendar information by displaying black on a white background, the liquid crystal display panel is also an interesting display device with a highly varied appearance.

If the specific wavelength of the light transmitted through the color polarizing plate 28 is selected, that is, the color of the light is selected, the metallic tone can be displayed in various colors.

[ example 10]

Next, an example 10 of a liquid crystal display device according to the present invention will be described with reference to fig. 20 and 21. Fig. 20 and 21 are schematic cross-sectional views for explaining the structure of a liquid crystal display panel and the principle of color display, which are liquid crystal display devices, and the same parts as those in fig. 1 to 11 are assigned the same reference numerals and the explanation thereof is omitted. The directions of the stripes in the polarizing plates and the solid lines with arrows in fig. 20 and 21 have the same meanings as described with reference to fig. 9 and 10.

The structure of the liquid crystal display panel is different from the structure shown in fig. 18 and 19 only in that the color polarizer 28 as a color filter is disposed between the liquid crystal cell 12 and the reflective polarizer 16.

The color polarizing plate 28 is also a color polarizing plate that transmits only light of a specific wavelength (yellow in this example) in linearly polarized light having a vibration plane perpendicular to the easy transmission axis, and absorbs the other light.

As shown in fig. 20 and 21, the light incident on the liquid crystal display panel from the viewing side is totally transmitted through the absorption polarizer 14, becomes linearly polarized light having a vibration plane parallel to the easy transmission axis thereof (parallel to the paper surface), and is incident on the liquid crystal cell 12. When transmitting through the liquid crystal cell 12, the liquid crystal cell 12 is subjected to 90-degree phase modulation in the left half of the OFF state, and the direction of the vibration plane thereof is changed to linearly polarized light in a direction parallel to the easy transmission axis of the color polarizer 28, and the linearly polarized light is incident on the color polarizer 28.

Therefore, in the background portion where the liquid crystal cell 12 is in the OFF state, light other than yellow light is also yellow light, and as shown in fig. 20 and 21, the light is absorbed by the light-absorbing plate 13 after passing through the color polarizing plate 28 and also passing through the reflective polarizing plate 16 whose easy transmission axis is arranged parallel to the easy transmission axis of the color polarizing plate 28.

In a display region of characters or the like in which the liquid crystal cell 12 is in an ON state, light other than yellow is absorbed by the color polarizing plate 28 as shown in fig. 20. The yellow light is transmitted through the color polarizer 28 and enters the reflective polarizer 16, but the direction of the vibration plane is perpendicular to the easy transmission axis of the reflective polarizer 16, and therefore, the yellow light is specularly reflected by the reflective polarizer 16 and exits to the viewer through the opposite path. For this reason, almost all of the colored light entering the liquid crystal cell 12 is reflected and emitted to the viewer side as a result.

Therefore, with this liquid crystal display panel, various information such as time information and calendar information can be displayed in a dark or dark background with a bright colored metallic tone.

Therefore, when the liquid crystal display device is used as a display device of an electronic apparatus, the display device is more interesting and has a more varied appearance than a conventional electronic apparatus in which various information such as time information and calendar information is displayed in black on a white background.

If the specific wavelength of the light transmitted through the color polarizing plate 28 is selected, that is, the color of the light is selected, the metallic tone can be displayed in various colors.

In the 9 th and 10 th configuration examples, the color polarizer 28 may be provided on the viewing side of the absorption polarizer 14 or on the inner surface side of any one of the substrates in the liquid crystal cell 12, as in the color filter 18 described in the 1 st configuration example.

Various modifications other than color filter 18 described in configuration example 1 can be similarly applied to configuration examples 9 and 10 described above.

Possibility of industrial utilization

As is clear from the above description, the liquid crystal display device of the present invention can display various information in bright colors in colored metallic tone on a dark background, and can display various information in black or dark colors on a colored metallic tone background, and the display color can be arbitrarily selected.

Therefore, when the liquid crystal display device (liquid crystal display panel) is used as a display panel of various electronic devices, it is possible to provide an electronic device which is more interesting and has a colorful change in appearance than a conventional timepiece or other electronic device which displays various information such as time information or calendar information by displaying black on a white background.

Further, the present invention can be applied to a liquid crystal display device with a backlight which can be used even in an environment where no external light is present or where there is little external light.

The present invention is not limited to a liquid crystal display device in which time information, calendar information, or numerical information is displayed by numerals or the like, and the liquid crystal display panel may be a dot-matrix liquid crystal display panel in which arbitrary characters or graphics are displayed, or the present invention may be applied to a liquid crystal display device in which electrodes of a liquid crystal cell are formed in various patterns so that various graphics can be selectively displayed.

Claims (22)

1. A liquid crystal display device is composed of the following parts:

a liquid crystal cell in which liquid crystal is sealed between 2 transparent substrates each having electrodes on the inner surfaces thereof facing each other;

an absorption-type polarizing plate disposed on the viewing side of the liquid crystal cell and absorbing linearly polarized light having a vibration plane in a direction perpendicular to the easy transmission axis;

a reflective polarizer disposed on the opposite side of the liquid crystal cell from the viewing side and reflecting linearly polarized light having a vibration plane in a direction perpendicular to the easy transmission axis;

and a color filter disposed on a viewing side of the absorption polarizer or between the absorption polarizer and the reflection polarizer.

2. The liquid crystal display device of claim 1, wherein: the light absorbing plate is disposed on the side opposite to the viewing side of the reflective polarizing plate.

3. The liquid crystal display device of claim 1, wherein: the light scattering plate is disposed on the viewing side of the absorption type polarizing plate.

4. The liquid crystal display device of claim 1, wherein: a light scattering plate disposed on a viewing side of the absorption type polarizing plate; the light absorbing plate is disposed on the side opposite to the viewing side of the reflective polarizing plate.

5. The liquid crystal display device of claim 1, wherein: the backlight is disposed on the side opposite to the viewing side of the reflective polarizing plate.

6. The liquid crystal display device of claim 5, wherein: a semi-transmissive plate is provided between the reflective polarizing plate and the backlight.

7. The liquid crystal display device of claim 6, wherein: the semi-transmissive plate is an absorption-type polarizing plate.

8. The liquid crystal display device of claim 1, wherein: a light scattering plate disposed on a viewing side of the absorption type polarizing plate; the backlight is disposed on the side opposite to the viewing side of the reflective polarizing plate.

9. The liquid crystal display device of claim 8, wherein: a semi-transmissive plate is provided between the reflective polarizing plate and the backlight.

10. The liquid crystal display device of claim 9, wherein: the semi-transmissive plate is an absorption-type polarizing plate.

11. A liquid crystal display device as claimed in any one of claims 1 to 10, characterized in that:

the easy transmission axis of the absorption type polarization plate arranged at the viewing side of the liquid crystal unit is parallel to the long axis direction of the liquid crystal molecules at the viewing side in the liquid crystal layer of the liquid crystal unit,

the easy transmission axis of the reflective polarizing plate is parallel or perpendicular to the long axis direction of the liquid crystal molecules on the side opposite to the viewing side in the liquid crystal layer of the liquid crystal cell.

12. A liquid crystal display device as claimed in any one of claims 1 to 10, characterized in that:

the easy transmission axis of the absorption type polarization plate arranged at the viewing side of the liquid crystal unit is vertical to the long axis direction of the liquid crystal molecules at the viewing side in the liquid crystal layer of the liquid crystal unit,

the easy transmission axis of the reflective polarizing plate is parallel or perpendicular to the long axis direction of the liquid crystal molecules on the side opposite to the viewing side in the liquid crystal layer of the liquid crystal cell.

13. A liquid crystal display device as claimed in any one of claims 1 to 10, characterized in that: the color filter is a selective transmission type color filter which transmits only light of a specific wavelength.

14. The liquid crystal display device of claim 13, wherein: the color filter is formed by arranging a plurality of color filters having different specific wavelengths in a planar manner.

15. The liquid crystal display device of claim 13, wherein: the color filter includes 3 color filters, each having a wavelength of light of red, green, and blue, the 3 color filters being regularly arranged in a predetermined order.

16. The liquid crystal display device of claim 13, wherein: the color filter includes 3 color filters of light having the specific wavelengths of cyan, magenta, and yellow, which are regularly arranged in a predetermined order.

17. A liquid crystal display device as claimed in any one of claims 1 to 10, characterized in that: the above color filter is a color filter in which: only light of a specific wavelength among the linearly polarized light having the vibration plane perpendicular to the easy transmission axis is transmitted, and light of other wavelengths is absorbed, while all the linearly polarized light having the vibration plane parallel to the easy transmission axis is transmitted.

18. A liquid crystal display device as claimed in any one of claims 1 to 10, characterized in that: the color filter is a dielectric multilayer film that reflects light of a specific wavelength within incident light and transmits light of other wavelengths.

19. A liquid crystal display device as claimed in any one of claims 1 to 10, characterized in that: the liquid crystal layer of the liquid crystal cell is formed of twisted nematic liquid crystal, super twisted nematic liquid crystal, or guest-host liquid crystal.

20. A liquid crystal display device as claimed in any one of claims 1 to 10, characterized in that: the color filter is provided between the absorption polarizer and the liquid crystal cell.

21. A liquid crystal display device as claimed in any one of claims 1 to 10, characterized in that: the color filter is provided between the liquid crystal cell and the reflective polarizing plate.

22. A liquid crystal display device as claimed in any one of claims 1 to 10, characterized in that: the color filter is provided between the transparent substrate and the liquid crystal layer constituting the liquid crystal cell.