JP2005062718A - Color liquid crystal display - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a color liquid crystal display which uses a chiral liquid crystal, consumes low power, is made thin, and has completely new structure. <P>SOLUTION: In the liquid crystal display using the chiral liquid crystal in a liquid crystal layer, a laminated structure wherein a plurality of liquid crystal layers are laminated is adopted, each of liquid crystal layers is irradiated with light beams having colors different from one another in the three primary color beams of light from a lateral direction by a sidelight system, and the scattering degrees of each of irradiation light beams are controlled by variously controlling the magnitude of voltage applied to the liquid crystal layers. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a color liquid crystal display device.

  Color liquid crystal display devices are used as display devices in various consumer and industrial electric appliances such as personal computers and televisions. In most of the color liquid crystal display devices used in these electric devices, a pair of translucent substrates are bonded together via a seal member, and a transparent electrode layer is formed on the surface of the one substrate facing the other substrate. A transparent electrode layer, a color filter layer, an overcoat layer, and an alignment film are sequentially formed on the surface of the other substrate facing the one substrate, and are twisted and aligned in the space formed by the pair of substrates and the sealing member. A liquid crystal cell in which a liquid crystal layer made of liquid crystal (twisted nematic liquid crystal) is formed, a pair of polarizing plates bonded to both outer surfaces of the liquid crystal cell, and a backlight for irradiating light from these back surfaces It is provided (for example, patent document 1). Then, an electric field is applied using the transparent electrode layer of the pair of substrates sandwiching the liquid crystal layer between the liquid crystal layers, and light is utilized using a change in optical rotation due to a change in the alignment state of liquid crystal molecules according to the strength of the electric field. The color is displayed by controlling the transmission / cutoff of the image.

  Since such a conventional liquid crystal display device requires a pair of polarizing plates arranged on both sides of the liquid crystal cell, when the backlight illumination light passes through the pair of polarizing plates, There is a problem that most of the energy is lost. For this reason, even after the loss of light energy, it is necessary to irradiate light having a light intensity high enough to secure a sufficient amount of transmitted light from the liquid crystal cell, which hinders reduction of power consumption. Also, in general, the backlight is configured to obtain uniform surface illumination by combining a light source such as a fluorescent lamp and a reflector or a light guide, but when trying to reduce the thickness of the backlight having such a configuration, There arises a problem that the brightness is lowered or spots are noticeable. That is, the use of a backlight having high light intensity hinders further thinning of the liquid crystal display device.

  Accordingly, the present inventor has already filed a liquid crystal display device that performs display by irradiating light to a liquid crystal cell using a chiral liquid crystal in a liquid crystal layer from the side in order to save power and thin the liquid crystal display device. (Patent Document 2). In the above chiral liquid crystal, when no voltage is applied, a focal conic polydomain structure is formed, and the light irradiated from the side is scattered and emitted from the display surface to emit light, while the voltage is applied. As a result, the homeotropic alignment state is obtained, and the light irradiated from the side goes straight as it is, and there is no light emitted from the display surface, and the dark state can be obtained. This liquid crystal display device does not require a polarizing plate, an alignment film, and the like used in the general liquid crystal display device using the twisted nematic liquid crystal described above, and can be driven with power saving without attenuating irradiation light. Thinning can be achieved.

JP 7-1114019 A

JP 2001-201735 A

  However, in a liquid crystal display device using the above-mentioned chiral liquid crystal in a liquid crystal layer, when a color display is performed using a backlight and a color filter as in the above general liquid crystal display device (backlight method), a voltage is partially applied. When it is applied to transmit light in a homeotropic alignment state, light is scattered at a portion to be shielded, and a desired color is blurred and thinning is inhibited. On the other hand, in the case of irradiating light from the side of the liquid crystal cell (side light method), it is difficult to irradiate light of a plurality of colors independently.

  The present invention has been made in view of such a situation, and an object of the present invention is to provide a color liquid crystal display device having a completely new structure that can save power and can be thinned using the chiral liquid crystal.

  As a result of intensive research to realize colorization in a liquid crystal display device using a chiral liquid crystal as a liquid crystal layer, the present inventor has made a laminated structure in which a plurality of liquid crystal layers are laminated, and each of the liquid crystal layers has a light 3 When light of different colors in the primary color is irradiated from the side by the sidelight method, and the degree of scattering of each irradiation light is controlled by variously controlling the magnitude of the voltage applied to each liquid crystal layer, from the display surface It has been found that good light of each color can be emitted. That is, the present invention relates to the following color liquid crystal display devices (1) to (5).

  (1) A color liquid crystal comprising a liquid crystal cell in which three liquid crystal layers held between a pair of transparent substrates including a transparent electrode layer are laminated, and an irradiation means for irradiating each of the liquid crystal layers with light in a planar direction. In the display device, the liquid crystal layer has a cumulative structure of endoplasmic reticulum formed by wrapping grains of a liquid crystal component containing chiral liquid crystal with a transparent polymer thin film, and the irradiation means has red light in each liquid crystal layer, A color liquid crystal display device capable of emitting green light and blue light.

  In the color liquid crystal display device of the above (1), the liquid crystal cell has a cell structure in which at least three liquid crystal layers are laminated. These liquid crystal layers are composed of a transparent polymer thin film containing grains of liquid crystal components including chiral liquid crystals. It is the cumulative structure of the endoplasmic reticulum. Of the three liquid crystal layers, red light is emitted from one side, green light from the other liquid crystal layer, and blue light from the other liquid crystal layer from the side (in the plane direction). To). Therefore, by controlling the magnitude of the voltage applied to each liquid crystal layer, the three primary colors can be additively mixed to emit various colors of light from the display surface.

  In addition, according to the color liquid crystal display device of (1) above, since the irradiation means can be arranged around the liquid crystal cell, the thickness can be reduced. Further, since almost no loss of light energy occurs, the amount of light emitted from the light source of the irradiating means can be reduced, and power consumption can be reduced.

  Further, in the color liquid crystal display device of the above (1), the transparent electrode layer may be formed on almost the entire surface of the transparent substrate so that the entire display surface is displayed in a different color, or a pair of transparent substrates. A transparent electrode layer may be formed in a matrix on the surface of one of the transparent substrates to form a dot matrix display. When forming the transparent electrode layer in a matrix, each transparent substrate corresponding to each liquid crystal layer is laminated slightly shifted (shifted) in a plane, that is, each transparent substrate formed in a matrix is laminated. It is preferable to arrange the electrode layers so as not to overlap with the liquid crystal layer stacking direction. By arranging the transparent electrode layers in this way, the contrast of color display can be improved.

  Further, as the light source in the irradiating means, a sufficiently bright display is possible even with light having a light intensity much lower than that of a conventional backlight, so that an LED array or the like can be used in addition to a fluorescent tube and a fluorescent lamp.

  (2) A color liquid crystal comprising a liquid crystal cell in which three liquid crystal layers held between a pair of transparent substrates including a transparent electrode layer are laminated, and an irradiation means for irradiating each of the liquid crystal layers with light in a planar direction. In the display device, the liquid crystal layer has a cumulative structure of endoplasmic reticulum formed by wrapping grains of liquid crystal components including chiral liquid crystal with a transparent polymer thin film, and the irradiation means includes cyan light, A color liquid crystal display device capable of emitting magenta light and yellow light.

  According to the invention of (2), the same effect as that of the color liquid crystal display device of (1) can be obtained.

  (3) The color liquid crystal display device as described in (1) or (2) above, wherein a light shielding layer exhibiting light shielding properties is formed in a pattern on at least one surface of the transparent substrate holding the liquid crystal layer.

  According to the color liquid crystal display device of the above (3), full color display can be performed, color omission of each of the three primary colors can be prevented, color mixing can be prevented, color display contrast can be further improved, and display quality can be improved. Can do.

  (4) A liquid crystal cell in which three liquid crystal layers held between a pair of transparent substrates including a transparent electrode layer are laminated, irradiation means for irradiating light in a planar direction to each of the liquid crystal layers, and translucency And a black matrix substrate on which a light-shielding part having light-shielding properties is formed, wherein the liquid crystal layer encapsulates a grain of a liquid crystal component containing chiral liquid crystal with a transparent polymer thin film. A color liquid crystal display device having a cumulative structure of vesicles, wherein the irradiating means can irradiate the liquid crystal layers with red light, green light and blue light, respectively.

  According to the invention of (4) above, full color display can be performed, color omission of each of the three primary colors can be prevented, color mixing can be prevented, color display contrast can be further improved, and display quality can be improved.

  (5) A liquid crystal cell in which three liquid crystal layers held between a pair of transparent substrates including a transparent electrode layer are laminated, an irradiation means for irradiating light in a planar direction to each of the liquid crystal layers, and a light transmitting property And a black matrix substrate on which a light-shielding part having light-shielding properties is formed, wherein the liquid crystal layer encapsulates a grain of a liquid crystal component containing chiral liquid crystal with a transparent polymer thin film. A color liquid crystal display device having a cumulative structure of vesicles, wherein the irradiating means can irradiate the liquid crystal layers with cyan light, magenta light and yellow light, respectively.

  According to the invention of (5), the same effect as that of the color liquid crystal display device of (4) can be obtained.

  In the present specification, the chiral liquid crystal refers to a cholesteric liquid crystal (chiral nematic liquid crystal) or a mixture of a cholesteric liquid crystal and a chiral smectic C liquid crystal whose texture (structure) is changed in accordance with a change in electric field. It is used in a generic sense to refer to liquid crystal materials that change between domain texture and homeotropic texture.

  According to the present invention, since the irradiation means can be arranged around the liquid crystal cell, the thickness can be reduced. Further, since almost no loss of light energy occurs, the amount of light emitted from the light source of the irradiating means can be reduced, and power consumption can be reduced.

  Hereinafter, embodiments of a color liquid crystal display device according to the present invention will be described with reference to the drawings. FIG. 1 is a schematic sectional view of the color liquid crystal display device according to the first embodiment. The color liquid crystal display device includes a liquid crystal cell 1 and an irradiation means 2. The liquid crystal cell 1 has four transparent glass substrates 3, 4, 5, and 6 and is disposed so as to be sequentially overlapped from the display surface side (upper surface side). A transparent electrode layer 7 (for example, indium oxide doped with tin oxide (ITO electrode layer)) is patterned in a matrix on the lower surface of the uppermost glass substrate 3. Transparent electrode layers 8 and 9 are formed on substantially the entire upper and lower surfaces of the glass substrate 4 positioned second from the upper surface side. Transparent electrode layers 10 and 11 are respectively formed in a matrix pattern on the upper and lower surfaces of the third glass substrate 5. A transparent electrode layer 12 is formed on the entire upper surface of the glass substrate 6 located at the lowermost surface, and further, if necessary, aluminum is deposited on the upper surface (lower layer of the transparent electrode layer 12) or the lower surface of the glass substrate 6. Is processed into a mirror surface. Glass substrates 3 and 4, glass substrates 4 and 5, and glass substrates 5 and 6 are arranged to face each other at a predetermined interval defined by a spacer (not shown) by a peripheral seal member 13. Has been.

  The transparent electrode layers 7, 10, and 11 patterned in a matrix form are arranged so as not to overlap each other when viewed in a plan view.

  In a space surrounded by the two glass substrates 3 and 4 and the sealing member 13 In a space surrounded by the two glass substrates 4 and 5 and the sealing material 13, surrounded by the two glass substrates 5 and 6 and the sealing member 13 The first liquid crystal layer 14, the second liquid crystal layer 15, and the third liquid crystal layer 16 are filled and sealed in each of the spaces.

  These liquid crystal layers 14, 15, and 16 are grains formed by wrapping a small volume cholesteric liquid crystal (chiral liquid crystal) exhibiting a polydomain structure such as a focal conic state (polydomain state) with a transparent polymer thin film 9 (for example, This is a layer having a structure in which a large number of layers having a diameter of about 1 to 2 μm are stacked. Such a structure can be obtained, for example, by mixing a photopolymerizable polymer and a liquid crystal and depositing a small volume of the liquid crystal wrapped with a polymer thin film by photopolymerization phase separation. The thickness of the liquid crystal layers 14, 15, and 16 can be appropriately determined within a range of, for example, about 5 to 60 μm according to the application (application form). Is preferably about 7 to 15 μm (in the figure, the size of the endoplasmic reticulum (grain) is exaggerated compared to the thickness of the liquid crystal layers 14, 15, and 16. And draw).

  Further, lenses 20, 21, and 22 are disposed near one ends of the liquid crystal layers 14, 15, and 16 of the liquid crystal cell 1, respectively. These lenses 20, 21, and 22 serve to generate parallel light from the light emitted from the light sources 17, 18, and 19 and irradiate the liquid crystal layers 14, 15, and 16, respectively. Here, the first liquid crystal layer 14 is irradiated with red light in the plane direction, the second liquid crystal layer 15 is irradiated with green light in the plane direction, and the third liquid crystal layer 16 is irradiated with blue light in the plane direction. Is irradiated. It is possible to determine appropriately which color of light from among red light, green light, and blue light is applied to the liquid crystal layers 14, 15, and 16.

  Further, in the vicinity of the other end of each liquid crystal layer 14, 15, 16, reflecting mirrors 23, 24, 25 are arranged so as to face the lenses 20, 21, 22, respectively. , 15, 16 is less leaked to the outside of the liquid crystal layers 14, 15, 16, and the amount of light emitted to the display surface side is increased.

  Here, as shown in FIG. 1, the cholesteric (chiral) liquid crystal can form a polydomain structure (polydomain cholesteric liquid crystal) and scatter incident light when no voltage (electric field) is applied. On the other hand, when a high voltage (electric field) is applied, the chiral liquid crystal is in a homeotropic alignment state and has a property of causing the incident light to go straight as it is. In the first embodiment, the liquid crystal layers 14, 15, and 16 are composed of grains (small size) in which a small volume of such cholesteric liquid crystal (polydomain cholesteric liquid crystal when no voltage is applied) is wrapped with a transparent polymer thin film. In this way, in addition to light scattering by the polydomain structure, light scattering by the grain interface also occurs, so the light scattering effect as a whole is further enhanced. In addition, when the voltage application state is not applied or the applied voltage is lowered, the recovery speed from the homeotropic alignment state to the polydomain structure can be improved, and the responsiveness can be improved.

  That is, the cholesteric (chiral) liquid crystal forms a polydomain structure (polydomain cholesteric liquid crystal) when no voltage (electric field) is applied. The parallel light incident from the light is scattered by the polydomain structure and scattered at the interface 26 of the grain (endoplasmic reticulum), and is emitted to the display surface side of the liquid crystal cell 1. On the other hand, when a high voltage (electric field) is applied between the transparent electrode layers, the chiral liquid crystal is brought into a homeotropic alignment state, and the parallel light incident from the side into the liquid crystal layers 14, 15, 16 remains as it is. There is almost no light that goes straight through and passes through and is emitted to the display surface side of the liquid crystal cell 1. Such a cholesteric liquid crystal (chiral liquid crystal) can control the degree of homeotropic alignment according to the strength of the electric field, and various voltages can be applied to the liquid crystal layers 14, 15, and 16. By adopting such a combination, the degree of light scattering can be controlled, and the emission color from the light emitting surface side can be changed variously. Therefore, by using the transparent electrode layers 7, 10, and 11 patterned in a matrix shape and controlling the applied voltage in various ways, dot matrix display (pattern display) with various emission colors becomes possible.

  Specifically, the cholesteric liquid crystal can be composed of, for example, cholesteric liquid crystal, chiral smectic C liquid crystal and nematic liquid crystal, and the total amount of cholesteric liquid crystal and chiral smectic C liquid crystal is about 0.05 to 10% by weight in the liquid crystal component. (Preferably 0.3 to 1% by weight). It is well known that a cholesteric liquid crystal is mixed with a nematic liquid crystal even if even a little, and here it is assumed that a chiral smectic C liquid crystal is added to a cholesteric liquid crystal obtained by adding a cholesteric liquid crystal to a nematic liquid crystal. it can.

  The component of the transparent polymer thin film that encloses the cholesteric liquid crystal is not particularly limited as long as it can take a structure that covers a small volume of the wall surface of the liquid crystal component in order to fully express the wall effect. Can do. From the viewpoint of the manufacturing process, a transparent electrode layer was formed by mixing a mixture containing an ultraviolet / visible photopolymerization type prepolymer and / or monomer and a liquid crystal component (for example, cholesteric liquid crystal, chiral smectic C liquid crystal and nematic liquid crystal). After the four glass substrates 3, 4, 5, 6 are laminated and bonded, the glass substrates are injected, and ultraviolet / visible light (wavelength: about 350 to 400 nm) is injected into the injected mixture through the glass substrate. It is preferable to polymerize the prepolymer or monomer by irradiation. Through such treatment, a thin film polymer is formed in a state of wrapping the polydomain (focal conic) grain structure of the cholesteric liquid crystal, and the accumulation of endoplasmic reticulum in which the grains containing the polydomain are wrapped in the polymer thin film. A structure (cell-like structure) can be obtained more reliably.

  Therefore, a transparent polymer component that is obtained by mixing the prepolymer and / or monomer with a liquid crystal component to obtain a compatible state, and then polymerizing at around room temperature by irradiation with ultraviolet light or visible light is preferably used. be able to. As such a prepolymer or monomer, those generally known as ultraviolet / visible photopolymerization type prepolymers or monomers can be used, for example, acrylic, methacrylic, thioacrylic, etc. it can. More specifically, hydroxyethyl acrylate, phenoxyethyl acrylate, lauryl acrylate, 1,6-hexanediol diacrylate, polyethylene glycol acrylate, polytetramethylene glycol acrylate, trimethylpropane triacrylate, etc. or prepolymers thereof Can be used alone or in combination. In the present invention, it is particularly desirable that the glass transition temperature (Tg) of the polymer after polymerization is lower than the operating temperature range. In addition, what is necessary is just to set the polymerization degree of a prepolymer suitably according to kinds, such as a prepolymer used and a liquid crystal component.

  When a vesicle that wraps a cholesteric liquid crystal with a transparent polymer thin film by irradiating ultraviolet / visible light between glass substrates as described above, the transparent polymer component is usually about 5 to 20% by weight (preferably 7%). ˜15 wt%) and the liquid crystal component is usually about 95 to 80 wt% (preferably 93 to 85 wt%). When the transparent polymer component is less than 5% by weight, the polymer component may become a dispersed layer. Moreover, when the transparent polymer component exceeds 20% by weight, the driving voltage may be increased.

  Next, an example in which a light shielding layer is formed on the glass substrate 3 of the liquid crystal cell 1 in the color liquid crystal display device of the first embodiment will be described. FIG. 2 shows an enlarged sectional view of the waist of the glass substrate 3 on the uppermost side (display surface side). On the lower surface of the glass substrate 3, the transparent electrode layer 7 is patterned in a matrix, and the light shielding layer B is patterned continuously or adjacent to the periphery of the transparent electrode layer 7. Further, if necessary, light is similarly shielded around the transparent electrode layers 10 and 11 patterned on the upper and lower surfaces of the glass substrate 5 for driving the second liquid crystal layer 15 and the third liquid crystal layer 16. A layer may be formed. The light shielding layer B is formed between the patterned transparent electrode layers 7, 10, 11 when the liquid crystal cell 1 is viewed in plan view, that is, the transparent electrode layer 7-the light shielding layer B-the transparent electrode layer 10-. Glass substrates 3 and 5 are arranged so as to be light shielding layer B-transparent electrode layer 11.

  The light shielding layer B can be formed by patterning using a photographic technique by depositing a light reflective metal such as chromium on the lower surface of the glass substrate 3 by vacuum deposition or sputtering.

  In the above example, the light shielding layer B may be patterned to be continuous or adjacent to the transparent electrode layers 7, 10 and / or 11 of the glass substrate 3 and / or the glass substrate 5. When the liquid crystal cell 1 is viewed in a plan view, the liquid crystal cell 1 is shifted with the transparent electrode layers 7, 10, and 11. That is, the light shielding layer B-transparent electrode layer 7 -transparent electrode layer 10 -transparent electrode layer 11 -light shielding layer B Glass substrates 3 and 5 are arranged so that.

  Furthermore, in the above example, each of the first to third liquid crystal layers 14, 15, 16 is irradiated with red light, green light, and blue light. In the present invention, light of these colors is used. Instead of cyan light, magenta light, and yellow light may be used.

  Next, as Embodiment 2, a case where a black matrix substrate is applied to the liquid crystal cell 1 of the above embodiment will be described. FIG. 3 shows a schematic cross-sectional view of the color liquid crystal display device of the second embodiment. The color liquid crystal display device includes a liquid crystal cell 30 in which a black matrix substrate 31 is attached to the upper surface of the glass substrate 3 on the display surface side (uppermost layer side) of the liquid crystal cell 1 of the color liquid crystal display device of the first embodiment. Is. The black matrix substrate 31 has a light shielding layer B 'formed on the lower surface thereof, and light shielding portions and light transmitting portions are alternately formed. Then, when the liquid crystal cell 30 is viewed in plan, the light shielding layer B ′ is shifted with each of the transparent electrode layers 7, 10, 11, that is, the light shielding layer B′-transparent electrode layer 7 -transparent electrode layer 10 -transparent. The glass substrates 3 and 5 are arranged so as to be an electrode layer 11-a light shielding layer B ′.

It is a schematic sectional drawing which shows the color liquid crystal display device which concerns on Embodiment 1 of this invention. FIG. 3 is an enlarged cross-sectional view of the waist when a light shielding layer is formed on the uppermost glass substrate of the liquid crystal cell 1 in the color liquid crystal display device of the first embodiment. It is a schematic sectional drawing which shows the color liquid crystal display device which concerns on Embodiment 2 of this invention.

Explanation of symbols

1,30 Liquid crystal cell 2 Irradiation means 3, 4, 5, 6 Glass substrate 7, 8, 9, 10, 11, 12 Transparent electrode layer 14 First liquid crystal layer 15 Second liquid crystal layer 16 Third liquid crystal layer 17 , 18, 19 Light source 20, 21, 22 Lens 23, 24, 25 Reflector 31 Black matrix substrate B, B 'Light shielding layer

Claims (5)

A color liquid crystal display device comprising: a liquid crystal cell in which three liquid crystal layers held between a pair of transparent substrates including a transparent electrode layer are laminated; and an irradiating means for irradiating each liquid crystal layer with light in a planar direction. There,
The liquid crystal layer has a cumulative structure of endoplasmic reticulum formed by enclosing grains of liquid crystal components containing chiral liquid crystal with a transparent polymer thin film,
A color liquid crystal display device, wherein the irradiating means can irradiate each of the liquid crystal layers with red light, green light and blue light. A color liquid crystal display device comprising: a liquid crystal cell in which three liquid crystal layers held between a pair of transparent substrates including a transparent electrode layer are laminated; and an irradiating means for irradiating each liquid crystal layer with light in a planar direction. There,
The liquid crystal layer has a cumulative structure of endoplasmic reticulum formed by enclosing grains of liquid crystal components containing chiral liquid crystal with a transparent polymer thin film,
A color liquid crystal display device, wherein the irradiating means can irradiate each liquid crystal layer with cyan light, magenta light and yellow light, respectively.   3. The color liquid crystal display device according to claim 1, wherein a light shielding layer exhibiting a light shielding property is formed in a pattern on at least one surface of the transparent substrate holding the liquid crystal layer. A liquid crystal cell in which three liquid crystal layers held between a pair of transparent substrates including a transparent electrode layer are laminated, an irradiating means for irradiating each liquid crystal layer with light in a plane direction, and a transparent material exhibiting translucency. A color liquid crystal display device comprising a light matrix and a black matrix substrate on which a light shielding portion exhibiting light shielding properties is formed,
The liquid crystal layer has a cumulative structure of endoplasmic reticulum formed by enclosing grains of liquid crystal components containing chiral liquid crystal with a transparent polymer thin film,
A color liquid crystal display device, wherein the irradiating means can irradiate each of the liquid crystal layers with red light, green light and blue light. A liquid crystal cell in which three liquid crystal layers held between a pair of transparent substrates including a transparent electrode layer are laminated, an irradiating means for irradiating each liquid crystal layer with light in a plane direction, and a transparent material exhibiting translucency. A color liquid crystal display device comprising a light matrix and a black matrix substrate on which a light shielding portion exhibiting light shielding properties is formed,
The liquid crystal layer has a cumulative structure of endoplasmic reticulum formed by enclosing grains of liquid crystal components containing chiral liquid crystal with a transparent polymer thin film,
A color liquid crystal display device, wherein the irradiating means can irradiate each liquid crystal layer with cyan light, magenta light and yellow light, respectively.

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