JP2005283969A - Liquid crystal display device and liquid crystal projector using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a liquid crystal display device with high display quality that increases the heat radiation performance of a display panel in use environment wherein intense light is made incident on a projection type liquid crystal projector etc., and has a high contrast and small display luminance unevenness. <P>SOLUTION: The liquid crystal display device 1 has a liquid crystal layer 4 sandwiched between a TFT substrate 2 and an opposite substrate 3 with film surface confronted with each other. Then a dustproof substrate 6 is stuck on the side of the opposite substrate 3 where light is made incident and a heat radiation substrate 5 is stuck on the side of the TFT substrate 1 where light is projected with an adhesive having high flexibility. Further, outer circumferential regions of the TFT substrate 2, opposite substrate 3, heat radiation substrate 5, and dustproof substrate 6 that no light passes through are held by a holder 7. The heat radiation substrate 5 is composed of a single-crystal substrate or polycrystalline substrate with high heat conductivity which is made of a crystal system of a cubic system. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a liquid crystal display device, and more particularly to a structure of a liquid crystal display device in which strong light is incident in a liquid crystal projector or the like.

  In a projection type liquid crystal projector, an image signal is input to a liquid crystal display device, and the image is formed and displayed on a screen. The active matrix substrate and the counter substrate used in this liquid crystal display device each have a thickness of about 0.5 to 1.2 mm, and the active matrix substrate surface and the counter substrate surface can also be image forming positions. Therefore, if there are foreign objects such as scratches and dust on the surface of the active matrix substrate or the surface of the counter substrate, the shadow is projected on the screen and the display quality is deteriorated. In order to prevent this problem, an insulating glass substrate called a dust-proof glass having a thickness of about 0.5 to 2.0 mm is bonded to the surface of the active matrix substrate and the surface of the counter substrate. Thereby, even if there are scratches or foreign matter on the surface of the dust-proof glass, the surface of the dust-proof glass is deviated from the focal position.

  On the other hand, recent projection-type liquid crystal projectors require high-brightness, compact, high-quality devices that can display screens even in bright usage environments. For example, portable types have 3000 ANSI lumens or more, and mobile types have 2000 ANSI lumens or more. ing. Along with this, the light source of the projection type liquid crystal projector has become stronger, and the liquid crystal display device itself has become smaller and has higher image quality, so that the incident light per unit area of the panel has become stronger. Therefore, in the liquid crystal display device, the temperature of the panel itself rises due to heat absorption by incident light, and a temperature difference occurs between the central portion and the peripheral portion of the panel display surface. Due to the temperature difference of the panel, thermal stress is generated inside the glass substrate which is a panel member, and birefringence anisotropy (retardation) is generated in the glass substrate. In a liquid crystal display device that is usually placed between two polarizing plates whose extinction axes are orthogonal, the incident light that has passed through the incident-side polarizing plate is originally linearly polarized light, but becomes elliptically polarized light due to the retardation generated on the glass substrate. Light escapes from the side polarizer. Even during dark display, part of the light is lost, which causes a decrease in display quality such as a decrease in contrast and uneven display luminance.

  There is a technique disclosed in Patent Document 1 for the problem of the liquid crystal display device described above. In order to solve this problem, a glass substrate with high thermal conductivity is used as dust-proof glass to increase heat dissipation, lower the temperature of the entire panel, and reduce the thermal stress generated in the glass substrate. Retardation generated in is reduced. As a means of efficiently dissipating the image display element to achieve both brightness, high image quality, and high performance of the image display element, the light incident / exit surface translucent material of the image display element is non-crystalline and has a thermal conductivity. By using a high material, it is possible to cope with high brightness without degrading the image quality.

  FIG. 12 is a configuration diagram showing a schematic configuration of the video display element disclosed in Patent Document 1. As shown in FIG. The video display element 150 includes a display pixel 151 formed between the counter substrate 152 and the TFT substrate 153, and includes an incident-side translucent member 154 on the incident side and an output-side translucent member 155 on the output side. In addition, the surfaces of the incident-side translucent member 154 and the exit-side translucent member 155, that is, the surface of the image display element 150 face air. The incident side translucent member 154 and the exit side translucent member 155 have a thickness of about 0.5 to 2.0 mm, and are projection lenses focused on the display pixels 151 of the image display element 150. The attached foreign matter is shifted from the focal position so that the foreign matter such as dust attached to the surface of the image display element 150 (not shown) becomes difficult to be visually recognized on the screen (not shown). For example, a cooling fan (not shown) blows air to the surface of the image display element 150 configured in this way through the flow path 157, and the image display element 150 absorbs the irradiation light from the light source and generates heat. Heat is radiated from the surfaces of the translucent members 154 and 155 to cool them.

At this time, instead of quartz transparent glass, the YAG (yttrium, aluminum, garnet: Y ₃ Al ₅ O ₁₂ ) crystal axis is used as the material of the input / output side translucent members 154, 155 of the image display element 150. A non-crystalline material is used. When an image display element using a 0.9-inch liquid crystal image display element panel (allowable temperature 70 ° C.) is used in a liquid crystal projector having a luminous flux of 2000 lumens, quartz transparent glass is used as the light transmitting and transmitting side translucent member. When used, the ambient temperature was 30 ° C. and the temperature of the image display device was about 70 ° C. However, when amorphous YAG was used, the temperature of the image display device could be 65 ° C., and the image quality was lowered. It is said that an improvement of 5 ° C could be recognized.

JP 2003-131164 A (FIG. 1)

  However, the above-described prior art has the following problems.

  The first problem is that sufficient heat dissipation cannot be ensured with respect to a higher luminous flux. The amount of luminous flux on the exit side of a liquid crystal projector is required to be 3000 lumens or more as market needs. However, the conventional technology can cope with the light flux up to 2000 lumens, but cannot cope with the light flux beyond that. The reason for this is that YAG is used as a material having high thermal conductivity in order to dissipate heat from the surface of the incident / exit side translucent member. However, since the material used in the prior art is an amorphous material, that is, an amorphous material, it cannot be said that the material has sufficient heat conductivity to cope with high brightness.

  The second problem is that the difference in the coefficient of thermal expansion between the TFT substrate and the counter substrate constituting the liquid crystal display device increases depending on the selection of the substrate material. The reliability cannot be secured. In particular, when the quartz glass mainly used in the high-temperature polysilicon device is used as the TFT substrate and the YAG amorphous substrate is used as the counter substrate as shown in the prior art, the thermal expansion coefficient is low. Since a combination of substrate materials having a large difference is formed, the adhesive portion between the TFT substrate and the counter substrate is peeled off due to thermal stress.

  Accordingly, the object of the present invention has been made in view of the above-described problems, and in particular, in a projection type liquid crystal projector and the like, while improving the heat dissipation performance of the display panel in a use environment where strong light is incident, the liquid crystal display By reducing the retardation caused by the thermal stress of the substrate that constitutes the device and the residual retardation in the initial state as much as possible, even in a high-luminance environment such as a luminous flux of 3000 lumens or more, high contrast and uneven display luminance An object of the present invention is to provide a liquid crystal display device having a small display quality and a high display quality. Another object of the present invention is to increase the product reliability of the structure against thermal stress generated at the bonding portion between the active matrix substrate and the counter substrate.

  The liquid crystal display device according to the present invention has a liquid crystal sandwiched between a plurality of substrates, and is used, for example, in a liquid crystal projector. At least one of the plurality of substrates is a cubic crystal substrate. In other words, the present invention provides a projection display device that has a light-shielding film layer on at least an active matrix substrate or a counter substrate, holds the active matrix substrate and the counter substrate in a fixed gap, and encloses liquid crystal in the gap. This is a liquid crystal display device to be used. A plurality of insulating substrates including at least an active matrix substrate and a counter substrate are stacked, and at least one of the insulating substrates is a crystal substrate made of a cubic crystal system.

  The crystal substrate may be a single crystal substrate or a polycrystalline glass substrate, for example, yttrium aluminum garnet (YAG). At this time, the average of the in-plane retardation distribution with respect to light incident in the thickness direction of the single crystal substrate is preferably 0.1 nm or less. In addition, the average of the in-plane distribution of retardation with respect to light incident in the thickness direction of the polycrystalline substrate is preferably 0.4 nm or less, and more preferably 0.1 nm or less.

Further, in the case where the active matrix substrate and the counter substrate are stacked only, the counter substrate may have higher thermal conductivity than the active matrix substrate. When the material of the active matrix substrate is non-alkali glass and the material of the counter substrate is yttrium aluminum garnet (YAG), the difference in thermal expansion coefficient between the active matrix substrate and the counter substrate is 5 × 10 ^−6. / K or less. Further, when the active matrix substrate is made of silicon and the counter substrate is made of yttrium aluminum garnet (YAG), the difference in thermal expansion coefficient between the active matrix substrate and the counter substrate is 6 × 10 ^−6. / K or less.

  In the liquid crystal display device according to the present invention, when a plurality of insulating substrates including an active matrix substrate and a counter substrate are stacked, at least one of the insulating substrates has higher thermal conductivity than the other insulating substrates. May be included.

  A liquid crystal projector according to the present invention synthesizes a light source, color separation means for color-separating light emitted from the light source, one or a plurality of liquid crystal display devices according to the present invention, and an image displayed by the liquid crystal display device. A color synthesis optical system and a projection lens for enlarging and projecting the synthesized image on the screen are provided.

  Next, the operation of the liquid crystal display device according to the present invention will be described.

  In a transmissive projector or the like, as a general method for suppressing a temperature rise due to a light source and a temperature rise due to heat absorption of an optical system including a liquid crystal display device, the device is cooled by forced air cooling using a fan. How to improve the heat dissipation of the liquid crystal display device is important for the problem that the amount of heat absorbed per unit area of the panel increases due to the high brightness of the light source and the downsizing of the device.

  The liquid crystal display device generates heat mainly in a liquid crystal display pixel portion formed by an active matrix substrate and a counter substrate inside the panel. In order to form a wiring layer and an insulating film for forming a transistor element, a light shielding layer for shielding the liquid crystal element and the transistor element from light, and a liquid crystal element on the counter substrate and the active matrix substrate forming the liquid crystal display pixel portion It is formed of a laminated film such as an organic film. However, the light to be transmitted or reflected originally becomes unknown light due to scattering or multiple reflection at the film interface due to the difference in refractive index between the laminated films described above and a complicated step structure. Some result in absorbed light.

  Therefore, the heat radiation capacity of the panel surface where the glass substrate and the air convection layer are in contact with each other is almost constant regardless of the flatness and material of the glass substrate. It is effective to use a substrate having a high heat transfer capability. When the material composition is the same, thermal energy is easily transferred due to lattice vibration depending on the regularity of atomic arrangement due to the difference in crystal structure. Become. Therefore, the single crystal structure is most advantageous in terms of heat dissipation.

  However, ordinary crystals have birefringence anisotropy. For this reason, when a crystal substrate containing these is used, there arises a problem that the contrast deteriorates due to the influence of birefringence anisotropy. In order to avoid this, in the present invention, a crystal substrate including a cubic crystal is used. Cubic crystal systems are exceptionally optically isotropic and have no birefringence anisotropy. As described above, the present invention is characterized by being a cubic crystal substrate having crystallinity with excellent thermal conductivity and no birefringence anisotropy.

  It is effective to use an yttrium aluminum garnet (YAG) crystal substrate as an example of this crystal substrate. The YAG crystal substrate includes a polycrystalline glass substrate and a single crystal substrate, but the thermal conductivity of each substrate is approximately 10 times that of a non-alkali glass or quartz substrate for a liquid crystal display device that is generally used. About high. Among them, the thermal conductivity (14.0 W / m · K) of the YAG single crystal substrate is about 20% higher than the thermal conductivity (11.7 W / m · K) of the YAG polycrystalline glass substrate. Yes. Therefore, the YAG single crystal substrate has higher performance with respect to higher brightness and smaller size of the projector.

  On the other hand, in terms of optical properties, the crystal system of the YAG crystal substrate belongs to a cubic system, and the birefringence anisotropy does not occur because the refractive index of each axis is the same. In other words, since the occurrence of retardation due to misalignment between the deflection axis of light passing through the glass substrate and the crystal axis of the glass substrate can be suppressed, it is possible to eliminate the causes of display quality degradation such as contrast degradation and display luminance unevenness due to these. . In addition, the assembly workability is improved because the alignment accuracy is not required.

  Furthermore, by reducing the retardation remaining on the glass substrate in the initial state, display quality such as contrast and display luminance unevenness can be improved. The glass substrate which is a constituent member of the liquid crystal display device has residual retardation that varies depending on the material and manufacturing method in an initial state. The residual retardation tends to be smaller in the single crystal substrate than in the polycrystalline substrate. The residual retardation of the YAG single crystal substrate is 0.05 nm or less on average in the plane, and is about 1/5 compared with that of the YAG polycrystalline glass substrate. The contrast of the liquid crystal display device is determined by the sum of the residual retardation in the initial state and the retardation generated by thermal stress during operation, assuming that the driving of the liquid crystal element is in an ideal state. In order to achieve a contrast of 1000 or more, the in-plane average of the retardation value needs to be 4 to 5 nm or less, and the YAG polycrystalline glass substrate has almost no retardation value margin, but the YAG single crystal substrate has a sufficient margin. Can be secured.

  As described above, the YAG single crystal substrate exhibits excellent performance. However, if importance is attached to cost, a cheaper YAG polycrystalline glass substrate can be used. The YAG polycrystalline glass substrate is optically isotropic as a whole substrate because the crystal grains are oriented in various directions but each crystal grain is optically isotropic. Further, the YAG polycrystalline glass substrate is less expensive than the YAG single crystal substrate.

In addition, when the material of the active matrix substrate of the liquid crystal display device is non-alkali glass and the counter substrate is a YAG crystal substrate, the difference in thermal expansion coefficient between the active matrix substrate and the counter substrate is relatively small. Sufficient product reliability due to the structure represented by impact properties can be secured. If the difference in thermal expansion coefficient between the active matrix substrate and the counter substrate is 5 × 10 ⁻⁶ / K or less, the thermal shock resistance is satisfied. In particular, the thermal expansion coefficient (6.9 × 10 ⁻⁶ / K) of the YAG single crystal substrate is about 15% compared with the thermal expansion coefficient (8.0 × 10 ⁻⁶ / K) of the YAG polycrystalline glass substrate. It is getting smaller. For this reason, the use of a YAG single crystal substrate as the counter substrate reduces the difference in thermal expansion coefficient from the non-alkali glass of the active matrix substrate, thereby further improving the reliability.

  According to the present invention, by using a cubic crystal substrate as at least one of a plurality of substrates sandwiching liquid crystal, a liquid crystal display device having high heat dissipation performance and high contrast display characteristics can be obtained. The reason is. This is because the cubic crystal substrate has good thermal conductivity and no birefringence anisotropy. In particular, by selecting a single crystal substrate or a polycrystalline substrate having high thermal conductivity as the substrate constituting the liquid crystal display device, retardation caused by thermal stress generated on the entire substrate by incident light and residual retardation in the initial state can be reduced. It can be as small as possible. Therefore, even in a higher luminance environment, high contrast and display luminance unevenness can be reduced, that is, display image quality can be improved. Also, by using alkali-free glass, which is mainly used in low-temperature polysilicon devices, as the active matrix substrate and using YAG polycrystalline glass substrate as the counter substrate, the difference in thermal expansion between the two substrates should be made relatively small. Therefore, the product reliability of the structure against heat stress can be improved.

(First embodiment of liquid crystal display device)
FIG. 1 is a cross-sectional view showing a first embodiment of a liquid crystal display device according to the present invention. Hereinafter, this drawing will be mainly described.

  Although the detailed structure is not shown, as shown in FIG. 1, the liquid crystal display device 1 includes a TFT substrate 2 on which a TFT element, a drive circuit, a pixel electrode, and the like for driving the liquid crystal layer 4 are formed, and a TFT substrate. The counter substrate 3 on which the counter electrode arranged opposite to the pixels formed in 2 is formed sandwiches the liquid crystal layer 4 with the film surfaces facing each other. The dust-proof substrate 6 is bonded to the side of the counter substrate 3 on which light is incident, and the heat dissipation substrate 5 is bonded to the side of the TFT substrate 1 from which light is emitted with a highly flexible adhesive. Further, a holder 7 holds an outer peripheral region through which light of the TFT substrate 2, the counter substrate 3, the heat dissipation substrate 5, and the dustproof substrate 6 does not pass.

  When this liquid crystal display device 1 is used in a projection type liquid crystal projector, the deflected incident light 8 enters from the dust-proof substrate 6 side, and sequentially passes in the thickness direction of the counter substrate 3, the TFT substrate 2, and the heat dissipation substrate 5. Then, it passes as the outgoing light 9 from the side of the heat dissipation substrate 5. At that time, before the incident light 8 passes as the outgoing light 9, the liquid crystal display device 1 generates heat by being partially absorbed by the member as unknown light due to internal scattering, multiple reflection, and the like. Therefore, in the liquid crystal display device 1 that has generated heat, an air flow 11 is forcibly generated from the outside by an air cooling fan or the like. As a result, the heat generated inside moves toward the surface of the heat radiating substrate 5, the dust-proof substrate 6 or the holder 7 that comes into contact with the air as the heat flow 10, so that it is efficiently cooled by forced air cooling.

  In the liquid crystal display device 1 described in the following embodiment, the display area is described based on a 0.9-inch size, but the size is not particularly limited. For example, the emitted light beams in the case where the display areas are different may be compared with the amount of light per unit area of the display area as a design matter. This is. The same applies to the examples in other embodiments.

(Example 1)
Example 1 based on 1st Embodiment shown in FIG. 1 is demonstrated concretely.

The TFT substrate 2 and the counter substrate 3 in this example are made of alkali-free glass having a thermal expansion coefficient of 3.8 × 10 ⁻⁶ / K, a thermal conductivity of 1.05 W / m · K, and a thickness of 0.7 mm. I use it. This alkali-free glass is a glass substrate that has the same characteristics as those used as standard liquid crystal glass. An inexpensive liquid crystal display device with high performance can be manufactured.

The heat dissipation substrate 5 is a polycrystalline glass substrate having a high thermal conductivity with a thermal expansion coefficient of 8.0 × 10 ⁻⁶ / K, a thermal conductivity of 11.7 W / m · K, and a thickness of 1.1 mm. ing. The material is yttrium aluminum garnet (YAG). The YAG crystal substrate is characterized in that the crystal system belongs to a cubic system and the birefringence anisotropy does not occur because the refractive index of each axis is the same as the optical property. The dust-proof substrate 6 is a polycrystalline glass substrate having a thermal expansion coefficient of −6.0 × 10 ⁻⁷ / K, a thermal conductivity of 1.70 W / m · K, and a thickness of 1.1 mm. . The polycrystalline glass substrate has a crystal size of 0.1 μm or less, that is, an optical property that is sufficiently smaller than the wavelength of visible light.

  The thickness of each substrate is not particularly fixed. Even if the substrate thickness of the TFT substrate 2 and the heat dissipation substrate 5 overlapped or the substrate thickness of the counter substrate 3 and the dustproof substrate 6 overlapped, the surface of the heat dissipation substrate 5 and the dustproof substrate 6 have scratches or attached foreign matters, respectively. It is only necessary to have a dustproof structure that can be shifted from the image focal position. In other embodiments, the thickness of each substrate may be any value as long as a dustproof structure can be realized.

  When the liquid crystal display device 1 having the above-described configuration is used in a high-brightness projection type liquid crystal projector, the liquid crystal display device 1 absorbs light and generates heat, the central portion becomes a high temperature region, and the corner portion becomes a low temperature region. As shown in (a), a concentric temperature distribution occurs in the display area.

  In Example 1, when the emitted light corresponds to a 3000 lumen light beam of the projection type liquid crystal projector, the maximum temperature Tmax at the center of the display area on the surface of the heat dissipation substrate 5 is 62.3 ° C. The temperature difference ΔT was 2.8 ° C. The maximum temperature Tmax at the center of the display area on the surface of the dust-proof substrate 6 was 62.9 ° C., and the temperature difference ΔT between the center and the corner was 3.2 ° C.

  Further, when the emitted light corresponds to a light flux of 5000 lumens of the projection type liquid crystal projector, the maximum temperature Tmax at the center of the display area on the surface of the heat dissipation substrate 5 is 71.6 ° C., and the temperature difference between the center and the corner ΔT was 5.5 ° C. Further, the maximum temperature Tmax at the center of the display area on the surface of the dust-proof substrate 6 was 73.2 ° C., and the temperature difference ΔT between the center and the corner was 6.5 ° C.

  Note that the temperature difference ΔT (shown in FIG. 2 (a)) defines the position of 75% diagonally from the center of the display area toward the outer periphery as the temperature of the outer periphery, and the maximum temperature Tmax (FIG. 2). The difference between the temperature shown in FIG. The definition of the temperature difference ΔT is the same hereinafter.

  When the temperature distribution of the temperature difference ΔT occurs in the liquid crystal display device 1, thermal stress is generated inside the substrate due to the temperature difference ΔT. Then, due to the birefringence anisotropy of the substrate accompanying the generation of stress, retardation occurs in the deflected light passing in the thickness direction of the substrate constituting the liquid crystal display device 1. Such retardation causes partial light leakage when an image is displayed on the screen, particularly large light leakage at a maximum angle from the polarization axis. Therefore, the display quality is reduced by reducing contrast and in-plane variation. Reduce. This problem is the same in other embodiments.

  FIG. 2B shows the dark display level of the display area. In FIG. 2B, since the deflection axis is in the horizontal direction, a high luminance region where light is lost is generated at the four corners of the display area, and the darkest low luminance region is generated in the vertical horizontal direction of the display area. As a guide for ensuring display quality, the temperature difference ΔT needs to be suppressed to 10 ° C. or less. In the present embodiment, the temperature difference ΔT is satisfied even when the emitted light corresponds to the light flux of 5000 lumens of the projection type liquid crystal projector.

(Example 2)
Example 2 based on 1st Embodiment shown in FIG. 1 is demonstrated concretely.

The heat dissipation substrate 5 in this example has a high thermal conductivity single crystal having a thermal expansion coefficient of 6.9 × 10 ⁻⁶ / K, a thermal conductivity of 14.0 W / m · K, and a thickness of 1.1 mm. The board is used. The material is yttrium aluminum garnet (YAG). Compared with the physical properties of the YAG polycrystalline glass substrate used in Example 1, the YAG single crystal substrate is characterized by a thermal conductivity of about 20% higher and a thermal expansion coefficient of about 15% smaller. Other configurations of the liquid crystal display device 1 and the substrates used are the same as those in the first embodiment.

  When the liquid crystal display device 1 having the above-described configuration is used in a high-brightness projection type liquid crystal projector, the liquid crystal display device 1 absorbs light and generates heat, the central portion is in a high temperature region, and the corner portion is in the same manner as in the first embodiment. As shown in FIG. 3C, a concentric temperature distribution is generated in the display area.

  When the emitted light corresponds to a light flux of 3000 lumens of the projection type liquid crystal projector, the maximum temperature Tmax at the center of the display area on the surface of the heat dissipation substrate 5 is 61.8 ° C., and the temperature difference ΔT between the center and the corner is It was 2.4 ° C. The maximum temperature Tmax at the center of the display area on the surface of the dust-proof substrate 6 was 62.4 ° C., and the temperature difference ΔT between the center and the corner was 3.0 ° C.

  Further, when the emitted light corresponds to a light flux of 5000 lumens of the projection type liquid crystal projector, the maximum temperature Tmax at the center of the display area on the surface of the heat dissipation substrate 5 is 70.5 ° C., and the temperature difference ΔT between the center and the corner is It was 4.8 ° C. The maximum temperature Tmax at the center of the display area on the surface of the dust-proof substrate 6 was 72.3 ° C., and the temperature difference ΔT between the center and the corner was 5.9 ° C.

  FIG. 3D shows the dark display level of the display area. In FIG. 3D, since the deflection axis is in the horizontal direction, a high luminance region where light is lost is generated at the four corners of the display area, and the darkest low luminance region is generated in the vertical horizontal direction of the display area. As a guide for ensuring display quality, the temperature difference ΔT needs to be suppressed to 10 ° C. or less. In the present embodiment, the temperature difference ΔT is satisfied with a margin equal to or greater than that of the first embodiment even when the emitted light corresponds to the light flux of 5000 lumens of the projection type liquid crystal projector.

(Comparative Example 1)
As a comparative example based on the first embodiment shown in FIG. 1, the heat dissipation substrate 5 is made of the same material as the dustproof substrate 6, has a thermal expansion coefficient of −6.0 × 10 ⁻⁷ / K, and a thermal conductivity of 1.70 W. A polycrystalline glass substrate having a thickness of 1.1 mm / m · K was used. Other configurations of the liquid crystal display device 1 and the substrates used are the same as those in the first and second embodiments.

  As a result of temperature measurement and evaluation similar to those in Example 1 and Example 2, when the emitted light corresponds to a 3000 lumen light beam of the projection type liquid crystal projector, the maximum temperature Tmax at the center of the display area on the surface of the dustproof substrate 6 is 69. The temperature difference ΔT between the center portion and the corner portion was 6.9 ° C.

  Further, when the emitted light corresponds to a luminous flux of 5000 lumens of the projection type liquid crystal projector, the maximum temperature Tmax at the center of the display area on the surface of the dustproof substrate 6 is 85.6 ° C., and the temperature difference between the center and the corner ΔT was 13.7 ° C.

  As a guide for ensuring display quality, the temperature difference ΔT needs to be suppressed to 10 ° C. or less. On the other hand, in the first comparative example, the temperature difference ΔT is satisfied when the emitted light corresponds to the 3000 lumen light beam of the projection type liquid crystal projector, but the temperature difference when the emitted light corresponds to the 5000 lumen light beam. ΔT was not satisfied.

(Example 3)
Example 3 based on the first embodiment shown in FIG. 1 will be specifically described.

  In this embodiment, the TFT substrate 2, the counter substrate 3, the heat dissipation substrate 5 and the dustproof substrate 6 constituting the liquid crystal display device 1 are combined with substrates having different physical property values. FIG. 4 shows a measurement result of the initial retardation value of the liquid crystal display device 1 in this case, and a projection observation result of luminance unevenness of dark display in a high luminance environment.

The TFT substrate 2 and the counter substrate 3 are made of alkali-free glass having a thermal expansion coefficient of 3.8 × 10 ⁻⁶ / K, a thermal conductivity of 1.05 W / m · K, and a thickness of 0.7 mm. Yes. The dustproof substrate 6 includes a polycrystalline glass substrate having a thermal expansion coefficient of −6.0 × 10 ⁻⁷ / K, a thermal conductivity of 1.70 W / m · K, and a thickness of 1.1 mm as the dustproof substrate (A). Alternatively, a polycrystalline glass substrate having a thermal expansion coefficient of −2.0 × 10 ⁻⁶ / K, a thermal conductivity of 1.50 W / m · K, and a thickness of 1.1 mm is used as the dustproof substrate (B). The heat dissipation substrate 5 has a thermal expansion coefficient of 8.0 × 10 ⁻⁶ / K, a thermal conductivity of 11.7 W / m · K, a 1.1 mm thick YAG polycrystalline glass substrate, or a thermal expansion coefficient of 6. Use 9 × 10 ^-6 / K, YAG single crystal substrate with a thermal conductivity of 14.0 W / m · K, and a thickness of 1.1 mm, or the dust-proof substrate (A) or dust-proof substrate (B) described above. ing.

  The liquid crystal display device 1 (sample No. 3 in FIG. 4) using a YAG polycrystalline glass substrate for the heat dissipation substrate 5 and a dust-proof substrate (A) for the dust-proof substrate 6 has an initial retardation of 0.8 nm as a whole. It is relatively small as ~ 1.4 nm. For this reason, the luminance unevenness of dark display observed at the visual level was within the allowable range with the outgoing light flux equivalent to 3000 lumens of the projection type liquid crystal projector, but was not allowed with the outgoing light flux equivalent to 5000 lumens.

  Further, in the liquid crystal display device 1 (sample No. 4 in FIG. 4) using the YAG single crystal substrate as the heat dissipation substrate 5, the initial retardation of the entire liquid crystal display device 1 is as small as 0.5 nm to 1.0 nm. For this reason, the luminance unevenness of dark display observed at the visual level was within the allowable range for the output light flux equivalent to 3000 lumens of the projection type liquid crystal projector, but was also the allowable limit for the output light flux equivalent to 5000 lumens.

  The liquid crystal display device 1 (sample No. 5 in FIG. 4) using a YAG polycrystalline glass substrate as the heat dissipation substrate 5 and a dustproof substrate (B) as the dustproof substrate 6 has an initial retardation of 0.9 nm as a whole. It is relatively small at ˜1.2 nm. For this reason, the luminance unevenness of the dark display observed at the visual level was within the allowable range with the outgoing light flux equivalent to 3000 lumens of the projection type liquid crystal projector, but was also the allowable limit with the outgoing light flux equivalent to 5000 lumens.

  Further, in the liquid crystal display device 1 (sample No. 6 in FIG. 4) using a YAG single crystal substrate as the heat dissipation substrate 5, the initial retardation of the entire liquid crystal display device 1 is 0.6 nm to 0.8 nm. For this reason, the luminance unevenness of dark display observed at the visual level was within the allowable range even with the emitted light flux equivalent to 5000 lumens of the projection type liquid crystal projector. Thus, when a YAG crystal substrate is used for the heat dissipation substrate 5, it can be estimated that the retardation of the liquid crystal display device 1 in the operating state is small because the initial retardation is small and the heat conduction performance is good. In the liquid crystal display device 1 of this combination, it is estimated that the retardation at the time of operation necessary for obtaining a contrast of 1000 or more needs to be about 5.2 nm or less from desk calculation.

  On the other hand, in the liquid crystal display device 1 (sample No. 1 in FIG. 4) using the dust-proof substrate (A) as the heat dissipation substrate 5, the initial retardation of the entire liquid crystal display device 1 is as large as 1.0 nm to 1.8 nm. For this reason, the uneven brightness of the dark display observed at the visual level can be tolerated with the emitted light beam equivalent to 3000 lumens of the projection type liquid crystal projector, but not allowed with the emitted light beam equivalent to 5000 lumens.

  Moreover, the liquid crystal display device 1 (sample No. 2 in FIG. 4) using the dust-proof substrate (B) as the heat dissipation substrate 5 has a relatively large initial retardation of 1.1 nm to 1.5 nm of the entire liquid crystal display device 1. For this reason, the luminance unevenness of the dark display observed at the visual level was within the allowable range even with the outgoing light flux equivalent to 5000 lumens of the projection type liquid crystal projector. However, since the maximum temperature Tmax of the panel at 5000 lumens rose to 88 ° C., the display performance as a liquid crystal element could not be satisfied.

  In these combinations, since the dustproof substrate (A) and the dustproof substrate (B) have negative thermal expansion, the retardation caused by thermal stress is optically compensated, but the dustproof substrate (B) has more negative heat. Since the expansion coefficient is large, the effect of optical compensation is large. However, any combination has poor heat conduction performance, and the panel temperature rises due to heat generation in a high-luminance environment, so the display performance of the liquid crystal element is inevitably lowered. In the liquid crystal display device 1 of this combination, it is estimated that the retardation during operation necessary for obtaining a contrast of 1000 or more needs to be approximately 5.2 nm or less from the desktop calculation.

  For reference, the liquid crystal display device 1 (sample No. 7 in FIG. 4) having a configuration without the heat dissipation substrate 5 and the dustproof substrate 6 has a very small initial retardation of 0.2 nm to 0.3 nm. However, the uneven brightness of the dark display observed at the visual level is unacceptable even with a luminous flux equivalent to 3000 lumens of a projection type liquid crystal projector. In this combination, not only the retardation caused by thermal stress cannot be compensated, but also the thermal conductivity of the substrate is poor, so it can be estimated that the retardation during operation becomes larger than the allowable limit even if the initial retardation is small.

  FIG. 5 shows the relationship between the measurement results of the initial retardation and the thermal conductivity of the single substrates used for the TFT substrate 2, the counter substrate 3, the heat radiating substrate 5, and the dust-proof substrate 6 constituting the liquid crystal display device 1 described above. ing.

  As shown in FIG. 5, the initial retardation of the substrate belonging to the polycrystal is large as a whole. That is, the dust-proof glass (A) is 0.4 to 0.7 nm, the dust-proof glass (B) is 0.4 to 0.5 nm, and the YAG polycrystalline glass substrate is slightly small at 0.2 to 0.3 nm. is there. On the other hand, the initial retardation of a YAG single crystal substrate belonging to a single crystal is very small, less than 0.1 nm. Similarly, non-alkali glass substrates and quartz glass substrates belonging to amorphous materials are also very small, less than 0.1 nm.

  To summarize the contents described so far, in the liquid crystal display device 1 corresponding to the increase in the brightness of the projection type liquid crystal projector, the heat dissipation substrate 5 having a high thermal conductivity is necessary for suppressing the temperature rise of the liquid crystal display device 1, Specifically, a YAG crystal substrate is effective. Among YAG crystal substrates, the YAG polycrystalline glass substrate has a slightly large initial retardation. Therefore, the retardation of the entire liquid crystal display device 1 including the retardation due to thermal stress when using a YAG polycrystalline glass substrate can satisfy the contrast of 1000 or more when the emitted light beam of the projection type liquid crystal projector is equivalent to 3000 lumens, but is equivalent to 5000 lumens. Is the permissible limit per 1000 contrast (see FIG. 6A).

  Therefore, the initial retardation necessary for the YAG crystal substrate to ensure the brightness of 3000 lumens may be 0.4 nm or less for the heat dissipation substrate 5 alone. On the other hand, the initial retardation of the YAG single crystal substrate is small. Therefore, the retardation of the entire liquid crystal display device 1 including retardation due to thermal stress when using a YAG single crystal substrate can ensure a contrast of 1000 even when the emitted light beam of the projection type liquid crystal projector is equivalent to 5,000 lumens ( (Refer FIG.6 (b)). Therefore, the initial retardation necessary for the YAG crystal substrate to ensure the brightness of 5000 lumens may be 0.1 nm or less for the heat dissipation substrate 5 alone.

(Second Embodiment of Liquid Crystal Display Device)
FIG. 7 is a cross-sectional view showing a second embodiment of the liquid crystal display device according to the present invention. Hereinafter, this drawing will be mainly described.

  Although a detailed structure is not shown, as shown in FIG. 7, the liquid crystal display device 61 includes a TFT substrate 62 on which a TFT element, a drive circuit, a pixel electrode, and the like for driving the liquid crystal layer 64 are formed, and a TFT substrate. A counter substrate (heat radiating substrate) 63 provided with a counter electrode disposed opposite to the pixels formed in 62 sandwiches the liquid crystal layer 64 with the film surfaces facing each other. An outer peripheral region through which light of the TFT substrate 62 and the counter substrate (heat dissipation substrate) 63 does not pass is held by a holder 67.

  When this liquid crystal display device 61 is used in a projection-type liquid crystal projector, the deflected incident light 68 enters from the counter substrate (heat dissipation substrate) 63 side, and the thickness direction of the TFT substrate 62 from the counter substrate (heat dissipation substrate) 63. And sequentially passes as the outgoing light 9 from the TFT substrate 62 side. At that time, before the incident light 68 passes as the outgoing light 69, the liquid crystal display device 61 generates heat by being partially absorbed by the member as unknown light due to internal scattering, multiple reflection, and the like. Therefore, in the liquid crystal display device 61 that has generated heat, an air flow 71 is forcibly generated from the outside by an air cooling fan or the like. As a result, the heat generated inside moves toward the surface of the counter substrate (heat radiating substrate) 63, the TFT substrate 62 or the holder 67 that comes into contact with the air as the heat flow 70, so that it is efficiently cooled by forced air cooling.

Example 4
Example 4 based on 2nd Embodiment shown in FIG. 7 is demonstrated concretely.

The TFT substrate 62 in this example is made of alkali-free glass having a thermal expansion coefficient of 3.8 × 10 ⁻⁶ / K, a thermal conductivity of 1.05 W / m · K, and a thickness of 0.7 mm. Yes. The counter substrate (heat radiating substrate) 63 has a thermal expansion coefficient of 8.0 × 10 ⁻⁶ / K, a thermal conductivity of 11.7 W / m · K, and a thickness of 1.1 mm. The board is used. The material is yttrium aluminum garnet (YAG).

  When the liquid crystal display device 61 having the above-described configuration is used in a high-brightness projection type liquid crystal projector, the liquid crystal display device 61 absorbs light and generates heat, and as in the first and second embodiments, the central portion is in the high temperature region. The corner portion becomes a low temperature region, and a concentric temperature distribution is generated in the display area (not shown).

  In Example 4, when the emitted light corresponds to a 3000 lumen light beam of the projection type liquid crystal projector, the temperature difference ΔT between the display area center portion and the corner portion on the surface of the counter substrate (heat radiating substrate) 63 is 2.0 ° C. there were. Further, when the emitted light corresponds to a light beam of 5000 lumens of the projection type liquid crystal projector, the temperature difference ΔT between the display area center portion and the corner portion on the surface of the counter substrate (heat radiating substrate) 63 was 3.8 ° C.

The liquid crystal display device 61 of this example was subjected to a temperature cycle test. The test conditions are 0 ° C. on the low temperature side, 80 ° C. on the high temperature side, and 1 hour each. When a 240-cycle test was performed, the liquid crystal display device 61 operated normally without any abnormality in appearance. As shown in FIG. 8, the difference in thermal expansion coefficient between the non-alkali glass substrate used for the TFT substrate 62 and the YAG polycrystalline glass substrate used for the counter substrate (heat dissipation substrate) 63 is 4.2 ×. Since it is about 10 ⁻⁶ / K, it is an allowable range against thermal stress.

As a comparative example, the TFT substrate was a quartz substrate having a thermal expansion coefficient of 5.6 × 10 ⁻⁷ / K, and the temperature cycle test was performed in the same manner as described above. When the 24 cycle test was completed, peeling had already occurred at the bonding interface between the TFT substrate and the counter substrate.

(Example 5)
Example 5 based on 2nd Embodiment shown in FIG. 7 is demonstrated concretely.

The TFT substrate 62 in this example is made of alkali-free glass having a thermal expansion coefficient of 3.8 × 10 ⁻⁶ / K, a thermal conductivity of 1.05 W / m · K, and a thickness of 0.7 mm. Yes. The counter substrate (heat radiating substrate) 63 is a single crystal substrate having a high thermal conductivity having a thermal expansion coefficient of 6.9 × 10 ⁻⁶ / K, a thermal conductivity of 14.0 W / m · K, and a thickness of 1.1 mm. Is used. The material is yttrium aluminum garnet (YAG).

  When the liquid crystal display device 61 having the above-described configuration is used in a high-brightness projection type liquid crystal projector, the liquid crystal display device 61 absorbs light and generates heat, and the central portion is in a high temperature region as in the first and second embodiments. The corner portion becomes a low temperature region, and a concentric temperature distribution is generated in the display area (not shown).

  In the fifth embodiment, when the emitted light corresponds to a 3000 lumen light beam of the projection type liquid crystal projector, the temperature difference ΔT between the display area center portion and the corner portion on the surface of the counter substrate (heat radiating substrate) 63 is 1.6 ° C. there were. Further, when the emitted light corresponds to a light flux of 5000 lumens of the projection type liquid crystal projector, the temperature difference ΔT between the display area center portion and the corner portion on the surface of the counter substrate (heat radiating substrate) 63 was 3.2 ° C.

About the liquid crystal display device 61 of a present Example, the temperature cycle test was done on the same conditions as the above-mentioned. As a result, the liquid crystal display device 61 operated normally without any abnormal appearance. As shown in FIG. 8, the difference in thermal expansion coefficient between the non-alkali glass substrate used for the TFT substrate 62 and the YAG polycrystalline glass substrate used for the counter substrate (heat dissipation substrate) 63 is 3.1 ×. Since it is about 10 ⁻⁶ / K, it is more within the allowable range than Example 4 with respect to thermal stress.

(Third embodiment of liquid crystal display device)
FIG. 9 is a sectional view showing a third embodiment of the liquid crystal display device according to the present invention. Hereinafter, this drawing will be mainly described.

  Although a detailed structure is not shown, as shown in FIG. 9, the liquid crystal display device 81 includes a silicon substrate 82 on which a transistor element, a drive circuit, a pixel electrode, a reflective film layer, and the like for driving the liquid crystal layer 84 are formed. And a counter substrate (heat dissipating substrate) 83 on which a counter electrode disposed opposite to the pixels formed on the silicon substrate 82 is sandwiched the liquid crystal layer 84 with the film surfaces facing each other. . And the outer peripheral area | region which the light of the silicon substrate 82 and the opposing board | substrate (heat dissipation board) 83 does not pass is hold | maintained with the holder 87. FIG.

  When this liquid crystal display device 81 is used in a projection type liquid crystal projector, the deflected incident light 88 is incident from the counter substrate (heat radiating substrate) 83 side and reflected by a reflective film layer (not shown) of the silicon substrate 82. And it passes as the emitted light 89 from the opposing board | substrate (heat dissipation board) 83 side. At that time, before the incident light 88 passes as the outgoing light 89, the liquid crystal display device 81 generates heat by being partially absorbed by the member as unknown light due to internal scattering or multiple reflection. Therefore, in the liquid crystal display device 81 that has generated heat, an air flow 91 is forcibly generated from the outside by an air cooling fan or the like. As a result, the heat generated inside moves toward the surface of the counter substrate (heat radiating substrate) 83, the silicon substrate 82 or the holder 87 that comes into contact with the air as the heat flow 90, and thus is efficiently cooled by forced air cooling.

(Example 6)
Example 6 based on the third embodiment shown in FIG. 9 will be specifically described.

As the silicon substrate 82 in this embodiment, a single crystal silicon substrate having a thermal expansion coefficient of 2.3 × 10 ⁻⁶ / K, a thermal conductivity of 168 W / m · K, and a thickness of 0.7 mm is used. . The single crystal silicon substrate has a thermal conductivity that is two orders of magnitude higher than that of alkali-free glass, and is excellent in heat dissipation. The counter substrate (heat radiating substrate) 85 has a thermal expansion coefficient of 8.0 × 10 ⁻⁶ / K, a thermal conductivity of 11.7 W / m · K, a thickness of 1.1 mm, and a polycrystalline glass with high thermal conductivity. The board is used. The material is yttrium aluminum garnet (YAG).

  When the liquid crystal display device 81 having the above-described configuration is used in a high-brightness projection type liquid crystal projector, the liquid crystal display device 81 absorbs light and generates heat, and the central portion is in a high temperature region as in the first and second embodiments. The corner portion becomes a low temperature region, and a concentric temperature distribution is generated in the display area (not shown).

  In Example 6, when the emitted light corresponds to a 3000 lumen light beam of the projection type liquid crystal projector, the temperature difference ΔT between the display area center portion and the corner portion on the surface of the counter substrate (heat radiating substrate) 83 is 1.3 ° C. there were. In addition, when the emitted light corresponds to a light flux of 5000 lumens of the projection type liquid crystal projector, the temperature difference ΔT between the display area center portion and the corner portion of the surface of the counter substrate (heat radiating substrate) 83 was 2.5 ° C.

(Example 7)
Example 7 based on the third embodiment shown in FIG. 9 will be specifically described.

In addition, a method similar to that described above, the counter substrate (heat radiating substrate) 83 has a thermal expansion coefficient of 6.9 × 10 ⁻⁶ / K, a thermal conductivity of 14.0 W / m · K, and a thickness of 1.1 mm. A single crystal substrate of yttrium aluminum garnet (YAG) having high conductivity was used.

  When the liquid crystal display device 81 having the above-described configuration is used in a high-brightness projection type liquid crystal projector, the liquid crystal display device 81 absorbs light and generates heat, and the central portion is in a high temperature region as in the first and second embodiments. The corner portion becomes a low temperature region, and a concentric temperature distribution is generated in the display area (not shown).

  In Example 7, when the emitted light corresponds to a 3000 lumen light beam of the projection type liquid crystal projector, the temperature difference ΔT between the center of the display area and the temperature of the corner on the surface of the counter substrate (heat radiating substrate) 83 is 1.1 ° C. Met. Further, when the emitted light corresponds to the light flux of 5000 lumens of the projection type liquid crystal projector, the temperature difference ΔT between the center of the display area and the temperature of the corner on the surface of the counter substrate (heat radiating substrate) 83 is 2.1 ° C. there were.

(4th Embodiment of a liquid crystal display device)
FIG. 10 is a sectional view showing a fourth embodiment of the liquid crystal display device according to the present invention. Hereinafter, this drawing will be mainly described.

  Although a detailed structure is not shown, as shown in FIG. 10, the liquid crystal display device 101 includes a TFT substrate 102 on which a TFT element, a drive circuit, a pixel electrode, and the like for driving the liquid crystal layer 104 are formed, and a TFT substrate. A counter substrate (heat dissipating substrate) 103 on which a counter electrode disposed opposite to the pixels formed in 102 is formed sandwiches the liquid crystal layer 104 with the film surfaces facing each other. A dust-proof substrate 106 is bonded to the TFT substrate 101 side from which light is emitted with a highly flexible adhesive. Further, a holder 107 holds an outer peripheral region through which light of the TFT substrate 102, the counter substrate 3, and the dustproof substrate 106 does not pass.

  When this liquid crystal display device 101 is used in a projection type liquid crystal projector, the deflected incident light 108 enters from the counter substrate (heat radiating substrate) 103 side, and the counter substrate (heat radiating substrate) 103, TFT substrate 102, dustproof substrate. The light passes through sequentially in the thickness direction of 106 and passes as the emitted light 109 from the dust-proof substrate 106 side. At that time, before the incident light 108 passes as the outgoing light 109, the liquid crystal display device 101 generates heat by being partially absorbed by the member as unknown light due to internal scattering, multiple reflection, and the like. Therefore, the heated liquid crystal display device 101 forcibly generates an air flow 111 from the outside by an air cooling fan or the like. As a result, the heat generated inside moves toward the surface of the counter substrate (heat radiating substrate) 103, the dust-proof substrate 106 or the holder 107 that comes into contact with the air as the heat flow 110, so that it is efficiently cooled by forced air cooling.

(Example 8)
Example 8 based on the fourth embodiment shown in FIG. 10 will be specifically described.

The TFT substrate 102 in this embodiment uses alkali-free glass having a thermal expansion coefficient of 3.8 × 10 ⁻⁶ / K, a thermal conductivity of 1.05 W / m · K, and a thickness of 0.7 mm. The counter substrate (heat radiating substrate) 103 is a polycrystalline glass substrate having a thermal expansion coefficient of 8.0 × 10 ⁻⁶ / K, a thermal conductivity of 11.7 W / m · K, a thickness of 2.0 mm, and a high thermal conductivity. Is used. The material is yttrium aluminum garnet (YAG). The dust-proof substrate 106 is a polycrystalline glass substrate having a thermal expansion coefficient of −6.0 × 10 ⁻⁷ / K, a thermal conductivity of 1.70 W / m · K, and a thickness of 1.1 mm.

  When the liquid crystal display device 101 having the above-described configuration is used in a high-brightness projection type liquid crystal projector, the liquid crystal display device 101 absorbs light and generates heat, and the central portion is in a high temperature region as in the first and second embodiments. The corner portion becomes a low temperature region, and a concentric temperature distribution is generated in the display area.

  In Example 8, when the emitted light corresponds to a 3000 lumen light beam of the projection type liquid crystal projector, the maximum temperature Tmax at the center of the display area on the surface of the counter substrate (heat radiating substrate) 103 is 59.9 ° C. And the temperature difference ΔT between the corner portions was 1.7 ° C. Further, when the emitted light corresponds to the light flux of 5000 lumens of the projection type liquid crystal projector, the maximum temperature Tmax at the center of the display area on the surface of the counter substrate (heat radiating substrate) 103 is 66.8 ° C. The temperature difference ΔT from the part was 3.3 ° C.

About the liquid crystal display device 101 of a present Example, the temperature cycle test was done on the same conditions as the above-mentioned. As a result, the liquid crystal display device 101 operated normally without any abnormal appearance. For this result, as shown in FIG. 8, the difference in thermal expansion coefficient between the non-alkali glass substrate used for the TFT substrate 102 and the YAG polycrystalline glass substrate used for the counter substrate (heat dissipation substrate) 103 is 4.2 ×. Since it is about 10 ⁻⁶ / K, it is an allowable range against thermal stress.

Example 9
Example 9 based on the fourth embodiment shown in FIG. 10 will be specifically described.

The TFT substrate 102 in this embodiment uses an alkali-free glass having a thermal expansion coefficient of 3.8 × 10 ⁻⁶ / K, a thermal conductivity of 1.05 W / m · K, and a thickness of 0.7 mm. . The counter substrate (heat dissipating substrate) 103 has a high thermal conductivity single crystal having a thermal expansion coefficient of 6.9 × 10 ⁻⁶ / K, a thermal conductivity of 14.0 W / m · K, and a thickness of 2.0 mm. A glass substrate is used. The dust-proof substrate 106 is a polycrystalline glass substrate having a thermal expansion coefficient of −6.0 × 10 ⁻⁷ / K, a thermal conductivity of 1.70 W / m · K, and a thickness of 1.1 mm. Yes.

  When the liquid crystal display device 101 having the above-described configuration is used in a high-brightness projection type liquid crystal projector, the liquid crystal display device 101 absorbs light and generates heat, and the central portion is in a high temperature region as in the first and second embodiments. The corner portion becomes a low temperature region, and a concentric temperature distribution is generated in the display area.

  In Example 9, when the emitted light corresponds to a 3000 lumen light beam of the projection type liquid crystal projector, the maximum temperature Tmax at the center of the display area on the surface of the counter substrate (heat radiating substrate) 103 is 59.3 ° C. And the temperature difference ΔT between the corner portion was 1.5 ° C. Further, when the emitted light corresponds to a light flux of 5000 lumens of the projection type liquid crystal projector, the maximum temperature Tmax at the center of the display area on the surface of the counter substrate (heat radiating substrate) 103 is 66.0 ° C. And the temperature difference ΔT was 2.8 ° C.

About the liquid crystal display device 101 of a present Example, the temperature cycle test was done on the same conditions as the above-mentioned. As a result, the liquid crystal display device operated normally without any abnormality. For this result, as shown in FIG. 8, the difference in thermal expansion coefficient between the non-alkali glass substrate used for the TFT substrate 102 and the YAG polycrystalline glass substrate used for the counter substrate (heat dissipation substrate) 103 is 3.1 ×. Since it is about 10 ⁻⁶ / K, it is an allowable range against thermal stress.

(First embodiment of liquid crystal projector)
FIG. 11 is a block diagram showing a first embodiment of a projection type liquid crystal projector according to the present invention. Hereinafter, this drawing will be mainly described.

  As the liquid crystal display devices 121R, 121G, and 121B, the liquid crystal display devices obtained in Examples 1 to 9 of the present invention are used. In addition, the liquid crystal display device 121R,. A projection type liquid crystal projector can be constructed by using the liquid crystal display devices 121R,.

  This projection type liquid crystal projector has a light source 122, a deflection conversion element 123 that aligns the deflection axis of white light from the light source 122, and a color that separates the white light into three light beams of red, green, and blue by a dichroic mirror 124 and the like. A separation optical system, liquid crystal display devices 121R,... Equipped with three microlenses for red, green, and blue, and a mirror 125 for synthesizing images displayed by these liquid crystal display devices 121R,. A color synthesizing optical system including a condenser lens 126, a polarizing plate 127, a cross dichroic prism 128, and the like, and a projection lens 129 for enlarging and projecting the synthesized display image on a screen are configured.

  In this projection type liquid crystal projector, after the light emitted from the light source 122 is condensed by the reflector 130, the light beam is aligned by the deflection conversion element 123 and sequentially separated by the two dichroic mirrors 124. Is separated into luminous flux. Of the three primary color beams, the red beam is reflected by the mirror 125 and then illuminates the red liquid crystal display device 121R. The green light beam illuminates the liquid crystal display device 121G for green, and the blue light beam is sequentially reflected by the mirror 125, and then illuminates the liquid crystal display device 121B for blue. As the liquid crystal display devices 121R, 121G, and 121B for red, green, and blue, an active matrix type that drives the liquid crystal by arranging TFTs for each pixel is used. In addition, a microlens for condensing light at the opening of the pixel to improve luminance is formed. The images displayed on the red, green, and blue liquid crystal display devices 121R,... By the deflecting plates 127 provided before and after the respective liquid crystal display devices 121R,... Are combined by the cross dichroic prism 128, and then projected. The image is enlarged and projected on a screen (not shown) by the lens 129.

  In the projection type liquid crystal projector shown in this embodiment, the liquid crystal display device is shown as a transmission type as an example, but the configuration including the optical system is not limited to the configuration shown in this figure. The liquid crystal display device may be of a reflective type as long as the configuration of the optical system is changed appropriately. The projection type liquid crystal projector shown in the present embodiment is shown as a three-plate type liquid crystal display device as an example, but is not limited to the configuration shown in this figure including the optical system. The liquid crystal display device may be a single plate type as long as the configuration of the optical system is changed as appropriate.

1 is a cross-sectional view showing a first embodiment of a liquid crystal display device according to the present invention. FIGS. 2A and 2B are explanatory diagrams of a heat generation state and a display state associated therewith in the first embodiment. FIG. 2A shows the temperature distribution of the substrate surface in the display area of Example 1, and FIG. Indicates the brightness level of the dark display in the area. FIG. 3C is an explanatory diagram of a heat generation state and a display state associated therewith in the first embodiment. FIG. 3C shows the temperature distribution of the substrate surface in the display area of Example 2, and FIG. Indicates the brightness level of the dark display in the area. In 1st Embodiment, it is a graph which shows the initial stage retardation value at the time of combining each board | substrate, and the luminance unevenness level of a dark display. It is a graph which shows the relationship between the measurement result of the initial stage retardation of the board | substrate single-piece | unit which comprises the liquid crystal display device based on this invention, and thermal conductivity. FIGS. 6A and 6B are diagrams illustrating a relationship between retardation and contrast in the first embodiment, in which FIG. 6A is a graph showing a case where the initial retardation is large, and FIG. 6B is a graph showing a case where the initial retardation is small. It is sectional drawing which shows 2nd Embodiment of the liquid crystal display device which concerns on this invention. It is a graph which shows the relationship between the measurement result of a substrate single-piece | unit which comprises the liquid crystal display device based on this invention, and a thermal expansion coefficient. It is sectional drawing which shows 3rd Embodiment of the liquid crystal display device which concerns on this invention. It is sectional drawing which shows 4th Embodiment of the liquid crystal display device which concerns on this invention. 1 is a configuration diagram showing a first embodiment of a liquid crystal projector according to the present invention. FIG. It is sectional drawing which shows schematic structure of the conventional video display element.

Explanation of symbols

1, 61, 81, 101, 121, 121R, 121G, 121B Liquid crystal display device 2, 62, 82, 102 TFT substrate 3 Counter substrate 4, 64, 84, 104 Liquid crystal layer 5 Heat dissipation substrate 6 Dustproof substrate 7, 67, 87 , 107 Holder 8, 68, 88, 108 Incident light 9, 69, 89, 109 Emitted light 10, 70, 90, 110 Heat flow 11, 71, 91, 111 Air flow 63, 83, 103 Counter substrate (heat dissipation substrate)
82 Silicon substrate 122 Light source 123 Deflection conversion element 124 Dichroic mirror 125 Mirror 126 Condensing lens 127 Deflection plate 128 Cross dichroic prism 129 Projection lens 130 Reflector 150 Video display element 151 Display pixel 152 Opposing substrate 153 TFT substrate 154 Incident side translucent member 155 Emission side translucent member 157 Flow path

Claims (12)

In a liquid crystal display device in which liquid crystal is sandwiched between a plurality of substrates,
At least one of the plurality of substrates is a cubic crystal substrate,
A liquid crystal display device characterized by the above. The crystal substrate is a single crystal substrate;
The liquid crystal display device according to claim 1. The crystal substrate is a polycrystalline glass substrate;
The liquid crystal display device according to claim 1. The crystal substrate is made of yttrium aluminum garnet (YAG),
The liquid crystal display device according to claim 1. The average in-plane distribution of retardation for light incident in the thickness direction of the crystal substrate is 0.4 nm or less.
The liquid crystal display device according to claim 1. The average in-plane distribution of the retardation is 0.1 nm or less.
The liquid crystal display device according to claim 5. The plurality of substrates consists of only an active matrix substrate and a counter substrate, and the counter substrate has higher thermal conductivity than the active matrix substrate.
The liquid crystal display device according to claim 1. The active matrix substrate is made of alkali-free glass, the counter substrate is made of yttrium aluminum garnet (YAG), and a difference in thermal expansion coefficient between the active matrix substrate and the counter substrate is 5 × 10 ⁻⁶ / K or less. Is,
The liquid crystal display device according to claim 7. The active matrix substrate is made of silicon, the counter substrate is made of yttrium aluminum garnet (YAG), and a difference in thermal expansion coefficient between the active matrix substrate and the counter substrate is 6 × 10 ⁻⁶ / K or less. ,
The liquid crystal display device according to claim 7. The plurality of substrates is a laminate of a plurality of insulating substrates including an active matrix substrate and a counter substrate, and at least one of the insulating substrates has higher thermal conductivity than the other insulating substrates.
The liquid crystal display device according to claim 1. Used for projection or reflection type liquid crystal projectors,
The liquid crystal display device according to claim 1. A liquid crystal display device according to any one of claims 1 to 11, a light source, color separation means for color-separating light emitted from the light source and supplying the light to the liquid crystal display device, and the liquid crystal display device A color synthesizing optical system for synthesizing the image displayed by the projector, a projection lens for enlarging and projecting the image synthesized by the color synthesizing optical system on the screen,
LCD projector equipped with.

Images