JP2001255528A - Transmissive liquid crystal display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a transmissive liquid crystal display device, capable of increasing the cooling efficiency of the polarizing plate and reducing the number of components. SOLUTION: In the transmissive liquid crystal display device, equipped with a liquid crystal display panel 101 for displaying images, polarizing plate 102 provided on the light-emitting side of the liquid crystal panel 101, a transparent substrate 103 provided on the light-emitting side of the polarizing plate 102, a metal holding part 104 for hold a transparent substrate 103 and a color compositing prism 105 provided on the light-emitting side of the transparent substrate 104, the transparent substrate 103 has thermal conductivity of 1 W/m.k or higher and produces λ/2 phase delay. A substance 206, having thermal conductivity of 0.1 W/m.k or higher is filled between the metal holding part 104 and the transparent substrate 103.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a transmissive liquid crystal display device suitable for application to a liquid crystal projector, a liquid crystal television, and the like, and more particularly, to a method for efficiently cooling a polarizing plate provided on an emission side of a liquid crystal display panel. The present invention also relates to a transmission type liquid crystal device capable of arbitrarily rotating the polarization direction of emitted light.

[0002]

2. Description of the Related Art FIG.
And FIG. Here, FIG. 6 is an explanatory diagram showing a schematic structure of a conventional liquid crystal projector, and FIG. 7 is an explanatory diagram showing a structure around a prism in the conventional liquid crystal projector.

[0003] As shown in FIG.
A light source 601, such as a metal halide lamp that emits white light,
An elliptical or parabolic curved surface reflector 608 for condensing the light in one direction, and thereafter, in the order of light propagation, an infrared ray, an ultraviolet cut filter 602, an optical integrator 603, a condensing lens 604a, color separation means 605a and 605b, Optical lenses 604b, 604c, 604d, 604e, 604f,
Incident side polarizing plates 606a, 606b, 606c, transmissive liquid crystal panels 607a, 607b, 607c, electric fan 608
It has.

Further, as shown in FIG. 7, emission side polarizing plates 702a, 702b, 702c, λ / 2 plates 703a, 703
b, 703c, color combining prism 705, projection lens 706
It has.

[0005] The white light emitted from the light source 601 contains unnecessary infrared rays and ultraviolet rays, and these lights are removed by the infrared ray and ultraviolet ray cut filter 602.
Further, the light is collected by the condenser lenses 604a, 604b, 604c, 6
The light is condensed by 04d, 604e, and 604f.

[0006] Color separation means 605a and 605b for color-separating light from a light source are arranged between the condenser lenses.
Here, the light is separated into three primary colors, and is condensed on a transmission type liquid crystal panel corresponding to each light.

[0007] The incident side polarizing plate 6 disposed in front of the panel
06a, 606b, and 606c pass through transmissive liquid crystal display panels 607a, 607b, and
The light is incident on the liquid crystal display panel 607c, is modulated by each liquid crystal display panel, and passes through the output-side polarizing plates 702a, 702b, and 702c, whereby a screen is displayed.

The light that has passed through the exit-side polarizing plate is converted to a λ / 2 plate 70.
Light is incident on 3a, 703b, and 703c. Thereafter, the images of the three primary colors are combined by the color combining prism 705, and the combined image is enlarged and projected by a projection lens 706 on a screen (not shown) or the like in front.

The electric fan 608 mainly includes a liquid crystal display panel 607a, 607b, 607c, an output side polarizing plate 702a,
They are arranged to prevent the temperature of 702b and 702c from rising. Here, it is possible to increase the cooling effect by increasing the rotation speed of the electric fan 608. However, in this case, not only is the power consumption of the product increased, but also the noise is increased. I can't say.

Therefore, for the purpose of increasing the cooling efficiency of the polarizing plate, for example, as described in JP-A-10-20400, a heat-diffusing film is used for the polarizing plate.
Attachment of a TAC (sailulose triacetate) film or the like is currently widely used.

In order to enhance the cooling efficiency of the polarizing plate disposed on the surface of the liquid crystal panel, for example, Japanese Patent Application Laid-Open No.
277 and JP-A-11-249120 propose that sapphire glass having a thermal conductivity that is about 30 times higher than that of ordinary glass is arranged on the light emission side of a liquid crystal panel.

Japanese Patent Application Laid-Open No. Hei 5-341276 discloses that a transparent substrate itself having a high thermal conductivity is used for a liquid crystal panel to cool a polarizing plate disposed on the surface of the transparent substrate. Methods to increase efficiency have also been proposed.

Further, as a means often used recently, a λ / 2 plate is arranged between the polarizing plate and the transparent substrate, and is arranged at a distance from the liquid crystal panel.
Some transparent substrates also cool the surface opposite to the surface on which the polarizing plate and the λ / 2 plate are arranged to increase the cooling efficiency of the polarizing plate.

[0014]

However, as described in the above-mentioned Japanese Patent Application Laid-Open No. 10-20400, a TA
In the method of pasting a C film and forcibly cooling the polarizing plate by air, as the brightness of the displayed screen increases,
There is a problem that the load applied to the output side polarizing plate becomes very large, and the cooling of the polarizing plate becomes insufficient.

Further, as described in JP-A-11-231277 and JP-A-11-249120, sapphire glass is arranged on the light emission side of the liquid crystal panel, and is arranged on the liquid crystal panel emission side surface. In the method of improving the cooling efficiency of the polarizing plate, the color combining prism
As shown in the figure, since the spectral characteristics of reflection and transmission greatly change depending on the polarization of light, the polarization direction of light emitted from sapphire glass must be rotated according to the characteristics of the color combining prism. .

In this case, after the sapphire glass is emitted, it is necessary to further arrange λ / 2 plates 703a, 703b, and 703c, and rotate the polarization directions corresponding to the respective characteristics, thereby increasing the number of parts. there were.

Further, also in the device described in Japanese Patent Application Laid-Open No. 5-341276, since the polarization direction of the light emitted from the liquid crystal panel is similarly rotated, it is necessary to arrange a λ / 2 plate thereafter, and the number of parts is reduced. There is a problem that increases.

In the method of arranging the λ / 2 plate between the polarizing plate and the glass substrate and rotating the polarization direction, not only the number of components is increased but also the λ / 2 plate causes the heat flow to the transparent substrate. And the cooling efficiency of the polarizing plate is reduced.

The present invention has been made in view of the above-mentioned problems, and an object of the present invention is to provide a transmission type liquid crystal display device capable of increasing the cooling efficiency of a polarizing plate and reducing the number of components.

[0020]

According to a first aspect of the present invention, there is provided a liquid crystal display panel for displaying an image, a polarizing plate disposed on a light emitting side of the liquid crystal panel, and a light emitting surface of the polarizing plate. A transparent substrate disposed on the side, a metal holding portion for retaining the transparent substrate, and a prism for color synthesis disposed on the light emission side of the transparent substrate, a transmission type liquid crystal display device, The transparent substrate has a thermal conductivity of 1 W / m · K or more,
And a phase difference of λ / 2 is generated, and the thermal conductivity between the metal holding portion and the transparent substrate is 0.1 W / m ·
It is characterized by being filled with a substance of K or more.

As a result, not only can the polarizing plate be efficiently cooled, but also the transparent substrate causes a phase difference of λ / 2, so that the conventionally required λ / 2 plate can be eliminated. Thus, the number of parts can be reduced.

The second invention of the present application is characterized in that the transparent substrate is formed of a uniaxial anisotropic crystal.
Thus, by controlling the thickness of the crystal, a phase difference of λ / 2 can be easily generated.

The third invention of the present application is characterized in that the transparent substrate is formed of two uniaxially anisotropic crystals whose optical axes are oriented in different directions. As a result, the same phase difference can be generated for light incident at different angles.

A fourth invention of the present application is characterized in that a material having a thermal conductivity of 0.1 W / m · K or more is filled between the two uniaxial anisotropic crystals. Thereby, it is possible to avoid impairing the heat conduction between the transparent substrates.

According to a fifth aspect of the present invention, the transparent substrate rotates the polarization direction of light emitted from the liquid crystal display panel by 45 degrees. Accordingly, even if the polarization direction of the light emitted from the liquid crystal display panel is at an angle of 45 degrees with respect to the polarization direction defined by the polarization transmission and reflection characteristics of the prism, the polarization direction is rotated to the specified direction. It is possible to match.

According to a sixth aspect of the present invention, the transparent substrate rotates the polarization direction of light emitted from the liquid crystal display panel by 90 degrees. Thus, even if the polarization direction of the light emitted from the liquid crystal display panel is at an angle of 90 degrees with respect to the polarization direction defined by the polarization transmission and reflection characteristics of the prism, the polarization direction is rotated and the specified direction is changed. It is possible to match.

According to a seventh aspect of the present invention, the area of the polarizing plate is 90% or less of the area of the transparent substrate. As a result, the area where the transparent substrate comes into direct contact with air can be increased, and the cooling efficiency can be improved.

According to an eighth aspect of the present invention, an antireflection film is provided on the surfaces of the polarizing plate and the transparent substrate. This makes it possible to reduce light loss.

According to a ninth aspect of the present invention, the thermal conductivity between the transparent substrate and the color combining prism is 0.1 W / m.
-Characterized by being filled with a substance of K or more. This makes it possible to radiate heat also to the prism.

[0030]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a first embodiment of a transmission type liquid crystal display device according to the present invention will be described with reference to FIGS.

Here, FIG. 1 is a plan view showing a main part configuration of the transmission type liquid crystal display device of this embodiment, and FIG. 2 is a view showing the optical axis directions of two transparent substrates in the transmission type liquid crystal display device of this embodiment. FIG. 3 is a schematic cross-sectional view of a metal holding part in the transmission type liquid crystal display device of the present embodiment, and FIG. 4 is a diagram showing a crystal structure of a uniaxial anisotropic crystal of a transparent substrate in the transmission type liquid crystal display device of the present embodiment. FIG.

The transmission type liquid crystal display device of the present embodiment is shown in FIG.
As shown in the figure, the transmissive liquid crystal panels 101a, 101b,
101c, the output side polarizing plates 102a, 102b, 102
c, transparent substrates 103a, 103b, 103c, and metal holding plates 104a, 104b, 1
04c and a color combining prism 105.

The transparent substrates 103a, 103b, 103
c is a uniaxially anisotropic single crystal transparent substrate 201, 2 having the same crystal orientation and polished to the same thickness, as shown in FIG.
02 is formed by sticking the optical axes 203 and 204 in different directions.

Here, the transparent substrates 201 and 202 are 1
It has a thermal conductivity of W / m · K or more. The thermal conductivity between the two transparent substrates 201 and 202 is 0.1 W / m ·
A substance 205 having a temperature of K or more is filled.

The transparent substrates 201 and 202 are made of sapphire glass. The thermal conductivity of sapphire glass is 4
It is 2 W / m · K, and has a thermal conductivity 30 times or more that of quartz glass. Note that single-crystal sapphire glass has uniaxial anisotropy.

Further, as shown in FIG.
4 and the sapphire glass 103 have a thermal conductivity of 0.5.
A substance 206 of 1 W / m · K or more is filled.
Further, the incident side surface of the polarizing plate 102 and the transparent substrate 103
The anti-reflection films 207 and 20
8 is given.

The sapphire glass 103 is polished to a thickness that causes a phase difference of λ / 2 with respect to the incident light. Here, the thickness of the sapphire glass is preferably 0.1 μm or more. Further, the area of the polarizing plate 102 is 90% or less of the area of the transparent substrate 103.

The single crystal sapphire glass is a uniaxial anisotropic crystal as shown in FIG. When light is incident on a uniaxially anisotropic crystal, the refractive index differs between light that vibrates in a direction perpendicular to a plane (main cross section) including the optical axis and the propagation direction and light that vibrates in a parallel direction. The former is called an ordinary ray and the latter is called an extraordinary ray, and the C axis 401 is an optical axis.

The ordinary ray, the refractive index of the extraordinary ray of sapphire (n _o, n _e) are, respectively, 1.768 and 1.760. When the plane including the optical axis of the uniaxially anisotropic crystal is polished to an appropriate thickness, the ordinary ray and the extraordinary ray of light that is perpendicularly incident on the crystal at a specific wavelength are transmitted by being shifted by half a wavelength from each other, and λ / 2
It becomes a board. The relationship between the thickness of the substrate and the phase difference is represented by the following equation.

[0040]

(Equation 1)

In the case where the light is incident perpendicularly to the A-plane 404 of the sapphire single crystal, the refractive index of the ordinary / extraordinary ray is
Assuming that the design center wavelength is 550 nm, the phase difference (2m + 1)
To produce × π (m is an integer), the thickness should be 34, 103, 17
2,. . . It is calculated as μm.

However, when light having a solid angle is incident on the A surface 404, the light whose vibration surface is perpendicular to the main cross section does not change its refractive index depending on the angle between the optical axis and the incident light. The parallel light changes its refractive index according to the angle.

As a solution to this problem, it is preferable to use two bases of the R surface 402. The refractive index n ″ in a plane parallel to the main section is expressed as follows, where θ is the angle between the C axis (optical axis) 401 and the traveling direction of light.

[0044]

(Equation 2)

[0045] Here, n _o, n _e, respectively, ordinary ray, the refractive index of extraordinary ray. Using the above equation, in the example using the R-plane of the sapphire crystal, the refractive index of the light parallel to the main cross section of the light perpendicular to the R-plane 402 is 1.762.
Becomes From this value and Equation 1, when the R surface 402 is used, the thickness of the base for the sapphire glass to become a λ / 2 plate is 46, 138, 230,. . . It is calculated as μm.

When light having a certain solid angle is incident on the R surface 402 of sapphire glass, the light component in the main section becomes
As described above, the phase changes depending on the incident angle. Therefore, as shown in FIG. 2, this problem can be solved by attaching substrates having the same optical axis angle so that the optical axes are opposite to each other.

That is, the change in the refractive index within the main cross section, which appears on the A surface 404,
The problem is solved by using two bases of the R surface 402. In this case, the thickness of the sapphire substrate is 0.1 μm or more, and the thermal conductivity between the substrates is 0.1 W /
It is preferable that the material is filled with a substance having mK or more.

In the present embodiment, the area of the polarizing plate is 90% or less of the area of the transparent substrate to which the polarizing plate is attached, and the cooling effect can be increased by increasing the surface area in contact with air. .

Further, when the polarizing plate is attached to the color synthesizing prism, the glass material used for the color synthesizing prism generally has a low thermal conductivity. Thus, improvement in cooling efficiency can be expected.

As described above, in the present embodiment, the output-side polarization plate is attached to the two transparent substrates that are attached with the directions of the optical axes changed to each other. The heat generated from the plate passes through the transparent substrate, and is radiated from the back side when the transparent substrate is air-cooled. Further, even on the surface to which the polarizing plate is attached, heat is also radiated by the heat moving on the surface of the transparent substrate and flowing to the metal holding plate.

Further, the shift in the phase difference with respect to the solid angle light of the optics of the illumination system can be compensated by attaching two transparent substrates while changing their optical axis directions. By using the λ / 2 plate having such a base, it is possible to adjust the polarization direction to the characteristics of the color combining prism.

Next, the second type of the transmission type liquid crystal display device of the present invention will be described.
The embodiment will be described with reference to FIG. 5, but the same parts as those in the above-described first embodiment are denoted by the same reference numerals, and description thereof will be omitted. Here, FIG. 5 is a plan view of a main part of the transmission type liquid crystal display device of the present embodiment.

The transmission type liquid crystal display device of the present embodiment is shown in FIG.
As shown in the figure, a material having a conductivity of 0.1 W / m · K or more is filled between the transparent substrates 103a, 103b, 103c having a thermal conductivity of 1 W / m · K or more and the color combining prism 106. are doing. Thereby, the color combining prism 1
06 can also radiate heat.

[0054]

According to the first aspect of the present invention, a transparent substrate having a thermal conductivity of 1 W / m · K or more and having a phase difference of λ / 2 is used as the transparent substrate. Between the substrate and the substrate, a substance having a thermal conductivity of 0.1 W / m · K or more is filled, so that not only can the polarizing plate be efficiently cooled, but also the transparent substrate has a λ / 2 order. Since a phase difference is generated, the conventionally required λ / 2 plate can be eliminated, and the number of parts can be reduced.

According to the second aspect of the present invention, since the transparent substrate is formed of a uniaxial anisotropic crystal, a phase difference of λ / 2 can be easily generated by controlling the thickness of the crystal. It is possible.

According to the third aspect of the present invention, since the transparent substrate is formed of two uniaxial anisotropic crystals whose optical axes are oriented in different directions from each other, the transparent substrate is not affected by light incident at different angles. However, the same phase difference can be generated.

According to the fourth aspect of the present invention, since a substance having a thermal conductivity of 0.1 W / m · K or more is filled between two uniaxial anisotropic crystals, the transparent substrate Impairing the heat conduction of the substrate.

According to the fifth aspect of the present invention, since the polarization direction of the light emitted from the liquid crystal display panel is rotated by 45 degrees, the polarization direction of the light emitted from the liquid crystal display panel is Even at an angle of 45 degrees with respect to the polarization direction defined by the polarization transmission and reflection characteristics of the prism, the polarization direction can be rotated and adjusted to the specified direction.

According to the invention of claim 6 of the present application, since the polarization direction of the light emitted from the liquid crystal display panel is rotated by 90 degrees, the polarization direction of the light emitted from the liquid crystal display panel is Even if the angle is 90 degrees with respect to the polarization direction defined by the polarization transmission and reflection characteristics of the prism, the polarization direction can be rotated and adjusted to the specified direction.

According to the seventh aspect of the present invention, since the area of the polarizing plate is set to 90% or less of the area of the transparent substrate, the area where the transparent substrate comes into direct contact with air can be increased, and the cooling efficiency can be improved. It is possible to

According to the eighth aspect of the present invention, since an antireflection film is formed on the surfaces of the polarizing plate and the transparent substrate, light loss can be reduced.

According to the ninth aspect of the present invention, the thermal conductivity between the transparent substrate and the prism for color synthesis is 0.1 W / m.
-Since the material is filled with a substance of K or more, it is possible to radiate heat to the prism.

[Brief description of the drawings]

FIG. 1 is a plan view illustrating a configuration of a main part of a transmission type liquid crystal display device according to a first embodiment of the invention.

FIG. 2 is a schematic diagram showing the optical axis directions of two transparent substrates in the first embodiment of the transmission type liquid crystal display device of the present invention.

FIG. 3 is a schematic cross-sectional view showing a metal holding portion in the first embodiment of the transmission type liquid crystal display device of the present invention.

FIG. 4 is a schematic diagram showing a crystal structure of a uniaxial anisotropic crystal of a transparent substrate in the first embodiment of the transmission type liquid crystal display device of the present invention.

FIG. 5 is a plan view showing a configuration of a main part of a transmission type liquid crystal display device according to a second embodiment of the present invention.

FIG. 6 is a schematic plan view showing a schematic configuration of a conventional liquid crystal projector.

FIG. 7 is a schematic plan view showing a specific configuration around a color combining prism in a conventional liquid crystal projector.

FIG. 8 is an explanatory diagram illustrating spectral characteristics of a color combining prism.

[Explanation of symbols]

 101a, 101b, 101c Transmissive liquid crystal display panel 102a, 102b, 102c Polarizer 103a, 103b, 103c Transparent substrate 104a, 104b, 104c Metal holding unit 105 Color combining prism 106a, 106b, 106c Filling unit 201, 202 Transparent substrate 203 Transparent Optical axis 204 of base 201 Optical axis 205 of transparent base 202 205 Filled portion 206 Filled portion 207 Antireflection film 208 Antireflection film 401 C axis (optical axis) 402 R surface 403 C surface 404 A surface

Claims (9)

[Claims] 1. A liquid crystal display panel for displaying an image, a polarizing plate provided on a light emitting side of the liquid crystal panel, a transparent substrate provided on a light emitting side of the polarizing plate, and the transparent substrate In a transmissive liquid crystal display device including a metal holding portion for holding a substrate and a color combining prism disposed on a light emission side of the transparent substrate, the transparent substrate has a thermal conductivity of 1 W / m. A material having a thermal conductivity of 0.1 W / m · K or more between the metal holding portion and the transparent substrate, wherein the material has a phase difference of λ / 2 or more. A transmission type liquid crystal display device characterized by the above-mentioned. 2. The transmissive liquid crystal display device according to claim 1, wherein the transparent substrate is formed of a uniaxial anisotropic crystal. 3. The transmission type liquid crystal display device according to claim 1, wherein the transparent substrates are oriented in directions in which optical axes are different from each other.
A transmission type liquid crystal display device comprising two uniaxial anisotropic crystals. 4. The transmission type liquid crystal display device according to claim 3, wherein a thermal conductivity between the two uniaxial anisotropic crystals is 0.1 W.
A transmissive liquid crystal display device characterized by being filled with a substance having a density of at least / m · K. 5. The transmissive liquid crystal display device according to claim 1, wherein the transparent substrate rotates a polarization direction of light emitted from the liquid crystal display panel by 45 degrees. Transmissive liquid crystal display. 6. The transmissive liquid crystal display device according to claim 1, wherein the transparent substrate rotates a polarization direction of light emitted from the liquid crystal display panel by 90 degrees. Transmissive liquid crystal display. 7. The transmission type liquid crystal display device according to claim 1, wherein an area of the polarizing plate is 90% or less of an area of the transparent substrate. 8. The transmission type liquid crystal display device according to claim 1, wherein an anti-reflection film is provided on surfaces of the polarizing plate and the transparent substrate. 9. The transmissive liquid crystal display device according to claim 1, wherein a thermal conductivity between the transparent substrate and the color combining prism is 0.1 W / m · K or more. A transmissive liquid crystal display device filled with a substance.