JP2000112022A - Projection type display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent the temperature rising of a polarizing plate. SOLUTION: The polarizing plates 10 and 16 are respectively arranged on the light incident side of a liquid crystal light valve 13 and the light emitting side of it. Polarizing plate glasses 7 and 42 are stuck on both surfaces of the polarizing plate 10, and the polarizing plate glasses 43 and 19 are stuck on both surfaces of the polarizing plate 16. Thus, the polarizing plate glasses 7, 42, 43 and 19 whose heat conductivity is higher than that of the polarizing plates 10 and 16 are stuck on both surfaces of the polarizing plates 10 and 16, and are provided at a position separated from the liquid crystal light valve 13, so that the temperature rising of the polarizing plates 10 and 16 and the liquid crystal light valve 13 can be prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to a projection type liquid crystal display device using a liquid crystal light valve for image formation.

[0002]

2. Description of the Related Art Conventionally, as shown in FIG. 5, a polarizing plate is attached to a glass substrate of a liquid crystal light valve, or a polarizing plate alone is attached to a member connected to the liquid crystal light valve via a double-sided tape. The structure was general.

[0003]

However, in the above-mentioned prior art, the unnecessary polarized light component of the light emitted from the light source is absorbed only by the polarizing plate, and the absorbed unnecessary polarized light component is converted into heat. Deterioration of characteristics, thermal deformation, etc., resulting in image deterioration, and heat absorbed by the polarizing plate is conducted to the glass substrate of the liquid crystal light valve to increase the temperature rise of the liquid crystal light valve, thereby inducing poor alignment. There is a problem that it is difficult to guarantee the reliability when the operating environment temperature is high, such as deterioration of the image.

Further, it is necessary to provide a high-performance cooling device (for example, a blower fan) in order to cope with the heat. When using the cooling device, it generates a high noise, and requires a large space in design in order to increase the size of the device. There are also issues of high prices that must be secured. In particular, the problem of generating a high noise is a problem to be solved because it has an adverse effect of neglecting a beautiful image, such as an image of a quiet scene. Further, when a high-output light source is used for improving brightness, the above-described problem is further increased, and there is a major disadvantage that the brightness must be sacrificed to reduce the problem.

[0005] When using only the polarizing plate,
Not only does light incidence efficiency decrease due to surface reflection loss, leading to a reduction in the brightness of the device, but attaching a flake-shaped polarizing plate to a sheet metal or the like via a double-sided tape is not only completely fixed, but also Accuracy and assemblability are poor, and this is also a concern in device design.

Further, when a polarizing plate is attached to a glass substrate of a liquid crystal light valve using an attaching jig such as a roller, excessive force is applied to cause serious damage, and the yield is reduced as a defective product. This is another cause of expensive equipment. Also, at this time, it is highly possible that small scratches are made on the surface of the glass substrate or a polarizing plate is attached while impurities such as dust and hand grease are attached. It is very close to the image display position of the bulb, and is enlarged and projected as a shadow on the screen as information near the focal position by the projection lens,
This causes image deterioration.

Therefore, the present invention solves the above-mentioned conventional problems, and the object of the present invention is to provide a high reliability such as a wide range of guaranteed environmental temperature and no image deterioration, and to facilitate design. Another object of the present invention is to provide a bright, small, low-noise, low-cost projection type liquid crystal display device.

[0008]

A projection type liquid crystal display device according to the present invention comprises a light source, a light separating optical system, a liquid crystal light valve,
In a projection type liquid crystal display device including a photosynthesis optical system, a projection optical system, and a cooling device for cooling a liquid crystal light valve, a glass plate is attached to a polarizing plate disposed on a light incident side and an output side of the liquid crystal light valve. It is characterized by attaching.

Further, the glass plate to be attached to the polarizing plate is arranged such that the polarizing plate side is the liquid crystal light valve side on both the light incident side and the outgoing side of the liquid crystal light valve.

Further, a glass plate is attached to both sides of the polarizing plate.

Further, the present invention is characterized in that a glass plate having an antireflection film deposited on one surface is used as the glass plate, and the non-deposited surface side is attached to a polarizing plate.

[0012]

In the projection type liquid crystal display device constructed as described above, the heat conductivity of the glass plate is higher than the heat conductivity of the polarizing plate, so that the heat absorbed by the polarizing plate can be released to the glass plate.

Further, by attaching a glass plate to both surfaces of the polarizing plate, there are two surfaces from which heat can be released, so that the temperature rise can be further reduced.

When a glass plate is attached to only one side of the polarizing plate, the direction in which heat is conducted is opposite to that of the liquid crystal light valve by arranging the polarizing plate side to be the liquid crystal light valve side. (In a direction away from the liquid crystal light valve), the temperature rise of the polarizing plate and the liquid crystal light valve can be reduced. Then, the heat is taken away by the wind generated by the cooling device, and the temperatures of the polarizing plate and the liquid crystal light valve are reduced.

Further, by attaching the glass plate to the polarizing plate, the reflection occurring on the surface of the polarizing plate can be suppressed, so that the light incidence efficiency can be increased. Further, by attaching the glass plate to both surfaces of the polarizing plate, not only one surface but also the surface reflection of both surfaces can be suppressed, so that the light incidence efficiency can be further improved.

Further, when a glass plate on which an antireflection film is deposited is used, the surface reflection loss of the glass plate can be substantially eliminated, so that the light incidence efficiency can be further increased and a bright device can be realized.

[0017]

DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 is a configuration diagram of an optical system of a projection type liquid crystal display device according to an embodiment of the present invention. FIG. 1 also shows an embodiment in which a glass plate attached to a polarizing plate is arranged on the polarizing plate side on the liquid crystal light valve side.

In FIG. 1, among white light emitted from a light source 1 such as a metal halide lamp, a xenon lamp, and a halogen lamp, a heat ray (light in a wavelength region of about 720 nm or more) is reflected by a heat ray cut filter 2, and other light rays are reflected. (Light in a wavelength region of about 720 nm or less) is transmitted. The transmitted light is incident on the light separation optical system 3 and is transmitted by the red light transmitting dichroic mirror 4 to a red light (from about 590 nm to about 7 nm).
Light in the wavelength range up to 00 nm). The transmitted red light changes its traveling direction by the reflection mirror 5, passes through the polarizing plate glass 7, and absorbs unnecessary polarization components by the polarizing plate 10,
Liquid crystal light valve for red, selectively transmitting single polarized light component
3 is incident. On the other hand, light other than red light (cyan light) is reflected by the red light transmitting dichroic mirror 4 and enters the green light reflecting dichroic mirror 6.
The green light reflecting dichroic mirror 6 emits green light (about 51
It reflects light in a wavelength range from 0 nm to about 590 nm) and transmits other light, blue light (light in a wavelength range of about 510 nm or less). The reflected green light and transmitted blue light
Similarly to the red light, the light passes through the polarizing plate glasses 8 and 9, selectively transmits a single polarization component by the polarizing plates 11 and 12, and enters the green liquid crystal light valve 14 and the blue liquid crystal light valve 15.

Here, the functions of the polarizing plate and the liquid crystal light valve will be described. The liquid crystal light valve serves as a light waveguide as a light modulation element. Simply put, the incident light is changed in form and emitted. The role of this device is to transmit or block light by controlling it electrically. However, since light having an infinite number of polarization planes is mixed in the light source 1, when all of these lights are directly incident on the liquid crystal light valve, the lights of the respective polarization planes are respectively light-modulated and emitted. Cannot transmit or block the light, and cannot fulfill the above role. Therefore, in order for the liquid crystal light valve to function satisfactorily, it is necessary to select a light component of a single plane of polarization (single polarization component) from the above light. For a single polarization component,
Since only one type of light needs to be modulated, transmission and blocking can be controlled. A polarizing plate is used as a means for selecting the single polarization component. Polarizing plates 10, 11, 1
2 is used for selecting a single polarization component, and the polarizing plates 16, 17, and 18 are used for detecting a polarization component light-modulated by a liquid crystal light valve. Therefore, the light modulation is normally performed by the combination of the two polarizing plates on the light incident side and the light emitting side and the liquid crystal light valve. Here, since the polarizing plates 10, 11, and 12 selectively transmit only a single polarized light component, they absorb other polarized light components (about 60% of the incident light). Since the absorbed polarized component (unnecessary polarized component) is converted into heat, the temperature of the polarizing plate must be increased. In addition, when the polarization plane directions (polarization axis directions) of the polarizers 16, 17, and 18 do not coincide with the polarization plane directions of the polarization light modulated by the liquid crystal light valves 13, 14, 15, the polarization plates 16, 17, and 18 are polarized. Absorbs part or all of, and receives a temperature rise. Further, the rise in temperature of each polarizing plate causes the temperature of the liquid crystal light valve between the two polarizing plates to rise due to radiant heat from each polarizing plate. Therefore, the liquid crystal light valves 13, 14, 15 and the polarizers 10, 11, 12 are controlled by the blower fan 22, which is a cooling device installed below or above the liquid crystal light valve.
And between the polarizing plates 16, 17, and 18, the light incident side of the polarizing plates 7, 8, and 9, and the polarizing plates 19, 20, and 2.
It is necessary to let air flow through the light emitting side of No. 1 to forcibly remove heat.

Referring to FIG. Each color light incident on the liquid crystal light valve for each color is light-modulated as described above, and analyzed by the polarizing plates 16, 17, and 18, and
After passing through the polarizing plate glasses 19, 20 and 21, the light enters the photosynthetic optical system 23. The incident red light is transmitted through the green light reflecting dichroic mirror 24 and then combined with the green light reflected by the green light reflecting dichroic mirror 24 to become yellow light, which becomes a blue light reflecting dichroic mirror 26.
Through. The traveling direction of the incident blue light is changed by the reflection mirror 25, and the blue light reflection dichroic mirror 26 is changed.
And is combined with the above yellow light to become white light. The white light synthesized in this way enters the projection optical system, and is enlarged and projected by a projection lens 27 on a screen (not shown).

In FIG. 1, the position of the light source 1 is
8, and the position of the projection lens 27 is also possible on the extension of the optical axis 32. At this time, the characteristics of the dichroic mirror may be changed so that light separation and photosynthesis are performed smoothly. Further, the positions of the liquid crystal light valves 13, 14 and 15 for each color can be freely selected, and it is only necessary to change the characteristics of the four dichroic mirrors corresponding to each position.

FIG. 2 is a detailed view around the liquid crystal light valve of the embodiment of FIG. The heat conductivity of the polarizing plate glasses 7 and 19 is about 0.68 kcal / m · h · deg, whereas the polarizing plate 1 has a thermal conductivity of about 0.68 kcal / m · h · deg.
The thermal conductivity of 0 and 16 is about 0.22 kcal / m · h · deg. Therefore, heat is transferred from the polarizing plates 10 and 16 having low thermal conductivity to the polarizing plate glasses 7 and 19 having higher thermal conductivity.
To conduct. Arrows 33 and 34 in the figure indicate the direction of heat conduction, and the direction pointed to is the light separation optical system 3 or the photosynthesis optical system 23 which is opposite to the liquid crystal light valve side. That is, it is clear that the temperature rise of the liquid crystal light valve 13 is greatly reduced. As described above with reference to FIG. 1, the blower fan 2 installed below or above the liquid crystal light valve (the lower part in FIG. 2).
When the wind from 2 passes around the liquid crystal light valve 13, the polarizers 10 and 16, and the polarizer glasses 7 and 19,
Arrow 3 shows how they forcibly remove heat and flow out of them.
Shown at 5, 36, 37, 38. The heat to be forcibly taken away is, as explained above, the amount by which the temperature rise is reduced,
Less. Therefore, the capacity of the cooling device can be reduced, and a small-sized, low-noise, inexpensive blower fan can be used. This leads to a reduction in size, noise, and cost of the projection type liquid crystal display device, and also facilitates device design. In addition, since the cooling capacity of the cooling device can be sufficient, the output of the light source can be increased, and a bright device can be realized.

FIG. 3 shows details of the surface reflection loss of the liquid crystal light valve, the polarizing plate and the polarizing plate glass. When light passes between media having different refractive indices, it reflects at the interface (surface of the medium) and loses incident light. The loss varies depending on the incident angle of light, the refractive index of the medium, the surface condition, and the like. Then, when light is incident at right angles, the approximate surface reflection loss R is

[0025]

(Equation 1)

Can be expressed as Therefore, the larger the ratio of the refractive indexes, the larger the surface reflection loss. In FIG. 3A, when the incident light enters the polarizing plate glass 7 from the air layer, a surface reflection loss 101 occurs, and the polarizing plate glass 7
Surface reflection loss 102 when entering the adhesive layer between the substrate and the polarizing plate 10, and surface reflection loss 1 when entering the polarizing plate 10.
03, surface reflection loss 10 even when re-entering the adhesive layer
3. Surface reflection loss 102 when entering the glass plate 42;
Furthermore, a surface reflection loss 101 occurs when the light enters the air layer, and a surface reflection loss 104 occurs when the light further enters the liquid crystal light valve 13. In FIG. 3B, the polarizing plate 1
The process up to the surface reflection loss 103 at the time of incidence at 0 is the same as that of FIG. 3A, and thereafter, the surface reflection loss 105 occurs at the time of incidence at the air layer, and at the time of incidence at the liquid crystal light valve 13. Surface reflection loss 104 occurs. FIG.
In [C], when the incident light is incident on the polarizing plate 10, a surface reflection loss 105 occurs, and also when the incident light is incident on an air layer, the surface reflection loss 105 occurs.
3, the surface reflection loss 104 occurs. In any of the above cases, the light emitted from the liquid crystal light valve 13 undergoes a process reverse to that at the time of incidence, and causes respective surface reflection losses. Since an antireflection film is deposited on the polarizing plate glass 7, the surface reflection loss 101 is R (101) = 0 (2). The refractive index of the air layer is 1.00, where the refractive index of the polarizing plate glass 7 is 1.52, and the refractive index of the adhesive layer is
Since 1.48 and the refractive index of the polarizing plate 10 are 1.49, when they are substituted into the expression (1), the respective surface reflection losses are R (102) = 1.78 × 10 ^−4. 3) R (103) = 0.11 × 10 ⁻⁴ (4) R (105) = 0.039 (5) From the results of the above equations (1) to (5), the total surface reflection loss until the light enters the air layer immediately before the liquid crystal light valve 13 is R (FIG. 3A) = 3.78 × 10 ^−4. (6) R (FIG. 3B) = 0.0392 (7) R (FIG. 3C) = 0.078 (8) is there. As can be seen from the expressions (6), (7) and (8), the surface reflection loss is reduced to about half by attaching a glass plate on which an antireflection film is deposited to the polarizing plate, as compared with the case of using the polarizing plate alone. can do. Further, when a glass plate on which an antireflection film is deposited is attached to both surfaces of the polarizing plate, the surface reflection loss can be reduced by orders of magnitude, and is close to zero. Since there is the above-mentioned surface reflection loss even before the light passes through the liquid crystal light valve 13 and enters the photosynthetic optical system 23, the polarizing plate alone is used and the glass plate on which the anti-reflection film is deposited is attached to one side of the polarizing plate. Alternatively, the difference in the surface reflection loss when pasting on both surfaces appears more remarkably. Therefore, a brighter projection type liquid crystal display device can be realized. FIG. 4 shows a configuration diagram of an optical system of a projection type liquid crystal display device according to another embodiment of the present invention. In the figure, the same components as those in FIG. 1 are denoted by the same reference numerals. The process until light passes through the heat ray cut filter 2 from the light source 1 is the same as in the above-described embodiment. The transmitted white light passes through the polarizing plate glass 7, a single polarized component is selectively transmitted by the polarizing plate 10, and enters the light separation optical system 3. The light-separated color polarization components are light-modulated by the liquid crystal light valves 13, 14, and 15 for the respective colors, and enter the light combining optical system 23. The synthesized white light is analyzed by the polarizing plate 16, transmitted through the polarizing plate glass 19, and enlarged and projected on a screen by the projection lens 27. In this, the processes in the light keying optical system 3 and the light combining optical system 23 are as follows.
The description is omitted because it is similar to the above-described embodiment. The polarizing plate 10 and the polarizing plate glass 7 are placed at the entrance of the light separation optical system 3,
By arranging the polarizing plate 16 and the polarizing plate glass 19 at the exit of the photosynthetic optical system 23, the temperature rise of the liquid crystal light valve for each color can be reduced more than the same as in the embodiment of FIG.

[0027]

As described above, the projection type liquid crystal display device of the present invention can reduce the temperature rise of the polarizing plate by a very simple structure in which a glass plate is attached to the polarizing plate. Further, by attaching a glass plate to both sides of the polarizing plate as well as to one side, heat is released from two sides, so that the temperature rise can be further reduced. Also, the temperature rise of the liquid crystal light valve can be reduced by arranging the glass plate attached to the polarizing plate so that the polarizing plate side is the liquid crystal light valve side without attaching the polarizing plate to the liquid crystal light valve. It becomes possible. This reduction in temperature rise
This prevents deterioration of image quality due to deterioration of polarization characteristics and thermal deformation of the polarizing plate and poor orientation of the liquid crystal light valve, so that the range of guaranteed environmental temperature can be expanded and the reliability of the device increases, as well as the cooling device's lower capacity. be able to. Reducing the capacity means that a small, low-noise, inexpensive blower fan can be used, and this leads to a reduction in size, noise, and cost of the projection-type liquid crystal display device. In addition, this reduction in temperature rise means that the cooling device has extra cooling capacity,
As a result, the output of the light source can be increased, and the device can be made bright. In addition, the downsizing of the cooling device does not affect the other components in terms of space, thereby facilitating the design. In addition, by adopting a structure in which a glass plate is attached to a polarizing plate, it becomes a part with a certain level of mechanical strength from a flaky one, and it can be completely fixed,
The mounting accuracy is improved, and the assemblability is good. Therefore,
This also facilitates the design. Further, by attaching a glass plate on which an anti-reflection film is deposited on one or both surfaces of the polarizing plate, the surface reflection loss of light can be suppressed, the light incidence efficiency increases, and a bright device can be realized. Furthermore, without attaching the polarizing plate to the glass substrate of the liquid crystal light valve,
By attaching the liquid crystal light valve to a glass plate remote from the liquid crystal light valve, the yield is improved without treating the liquid crystal light valve as defective, and this also contributes to a reduction in the price of the device. Furthermore, since it is possible to avoid scratching the glass substrate of the liquid crystal light valve and to keep the state in which impurities remain attached, there is obtained an effect that there is no image deterioration and the reliability of the projection type liquid crystal display device can be further increased. .

[Brief description of the drawings]

FIG. 1 is a configuration diagram of an optical system of a projection type liquid crystal display device according to an embodiment of the present invention.

FIG. 2 is a detailed view around the liquid crystal light valve of FIG. 1;

FIG. 3 is a detailed explanatory diagram of a surface reflection loss of a liquid crystal light valve, a polarizing plate, and a polarizing plate glass.

FIG. 4 is a configuration diagram of an optical system of a projection type liquid crystal display device according to another embodiment of the present invention.

FIG. 5 is a configuration diagram of an optical system of a conventional projection type liquid crystal display device.

[Explanation of symbols]

1. Light source 3. Light separation optical system 7, 8, 9, 19, 20, 21, 42, 43 ... Polarizing plate glass ································································································································· 13 ··· Photosynthesis optical system 27 ······ Projection lens 28, 32 ····· Optical axis 33, 34 ··· · Heat conduction direction 35, 36, 37 , 38 ... wind flow 101,102,103,104,105 ... surface reflection loss

────────────────────────────────────────────────── ───

[Procedure amendment]

[Submission date] October 27, 1999 (1999.10.
27)

[Procedure amendment 1]

[Document name to be amended] Statement

[Correction target item name] Claims

[Correction method] Change

[Correction contents]

[Claims]

[Procedure amendment 2]

[Document name to be amended] Statement

[Correction target item name] 0008

[Correction method] Change

[Correction contents]

[0008]

According to the present invention, there is provided a projection display apparatus comprising: a light source; a light valve for modulating and emitting light from the light source; and a projection means for projecting the light modulated by the light valve. A projection display device comprising:
The light valve includes a light modulating unit, and a polarizing plate disposed on the light incident side of the light modulating unit, and a light transmitting plate having a higher thermal conductivity is attached to both surfaces of the polarizing plate. Wherein the polarizing plate is arranged at a position distant from the light modulating means.

[Procedure amendment 3]

[Document name to be amended] Statement

[Correction target item name] 0009

[Correction method] Change

[Correction contents]

Further, the projection display device of the present invention comprises a light source,
A light valve that modulates and emits light from the light source;
A projection display device comprising: a projection unit that projects light modulated by the light valve, wherein the light valve includes a light modulation unit, and a polarizing plate disposed on a light incident side of the light modulation unit. A light transmission plate having a higher thermal conductivity is attached to both surfaces of the polarizing plate, and the polarizing plate is arranged at a position distant from the light modulation unit. I do.

[Procedure amendment 4]

[Document name to be amended] Statement

[Correction target item name] 0010

[Correction method] Deleted

[Procedure amendment 5]

[Document name to be amended] Statement

[Correction target item name] 0011

[Correction method] Change

[Correction contents]

[0011] Further, an anti-reflection film is deposited on one surface of the light transmitting plate, and a non-deposited surface side of the light transmitting plate is attached to the polarizing plate.

[Procedure amendment 6]

[Document name to be amended] Statement

[Correction target item name] 0012

[Correction method] Change

[Correction contents]

[0012]

In the projection type display device constructed as described above, since the heat conductivity of the light transmitting plate is higher than that of the polarizing plate, the heat absorbed by the polarizing plate can be released to the light transmitting plate.

[Procedure amendment 7]

[Document name to be amended] Statement

[Correction target item name] 0013

[Correction method] Change

[Correction contents]

[0013] Further, by attaching the light transmitting plate to both surfaces of the polarizing plate, the surface from which heat can be released becomes two surfaces, so that the temperature rise can be further reduced.

[Procedure amendment 8]

[Document name to be amended] Statement

[Correction target item name] 0014

[Correction method] Deleted

[Procedure amendment 9]

[Document name to be amended] Statement

[Correction target item name] 0015

[Correction method] Change

[Correction contents]

Further, by attaching the light transmitting plate to the polarizing plate, reflection occurring on the surface of the polarizing plate can be suppressed, so that the light incidence efficiency can be increased. Further, by attaching the light transmission plate to both surfaces of the polarizing plate, not only one surface but also the surface reflection of both surfaces can be suppressed, so that the light incidence efficiency can be further improved.

[Procedure amendment 10]

[Document name to be amended] Statement

[Correction target item name] 0016

[Correction method] Change

[Correction contents]

Further, when a light transmitting plate on which an antireflection film is deposited is used, the surface reflection loss of the light transmitting plate can be substantially eliminated, so that the light incident light rate can be further increased and a bright device can be realized. .

[Procedure amendment 11]

[Document name to be amended] Statement

[Correction target item name] 0027

[Correction method] Change

[Correction contents]

[0027]

As described above, the projection type liquid crystal display device of the present invention can reduce the temperature rise of the polarizing plate by a very simple structure in which the light transmitting plate is attached to the polarizing plate. Further, by attaching a light transmitting plate to both sides of the polarizing plate as well as to one side, there are two surfaces that emit heat, so that the temperature rise can be further reduced. Further, by disposing the polarizing plate on the liquid crystal light valve without attaching it, it is possible to reduce the temperature rise of the liquid crystal light valve. This reduction in temperature rise can prevent deterioration of the image quality due to deterioration of the polarization characteristics and thermal deformation of the polarizing plate and poor orientation of the liquid crystal light valve, so that the guaranteed range of the environmental temperature can be expanded and the reliability of the device increases, as well as cooling. The capacity of the device can be reduced. Reducing the capacity means that a small, low-noise, inexpensive blower fan can be used, and this leads to a reduction in size, noise, and cost of the projection-type liquid crystal display device. In addition, this reduction in temperature rise has the effect that the cooling device has a margin in cooling capacity, the output of the light source can be increased accordingly, and the device can be brightened. And
The fact that the cooling device can be made smaller does not affect the other components in terms of space, thereby facilitating the design.
Also, by adopting a structure in which a light transmission plate is attached to a polarizing plate,
From the flake shape, it becomes a part having a certain level of mechanical strength, it can be completely fixed, the mounting accuracy is improved, and the assemblability is good. Therefore, the design is also easy from this point. Further, by attaching a light transmitting plate on which an anti-reflection film is deposited to both surfaces of the polarizing plate, the surface reflection loss of light can be suppressed, the light incidence efficiency increases, and a bright device can be realized. Furthermore, by attaching the polarizing plate to the light transmitting plate that is separated from the liquid crystal light valve without attaching the polarizing plate to the glass substrate of the liquid crystal light valve, the yield is improved without treating the liquid crystal light valve as defective, This also contributes to lowering the price of the device. Furthermore, since it is possible to avoid scratching the glass substrate of the liquid crystal light valve and to keep the state in which impurities remain attached, there is obtained an effect that there is no image deterioration and the reliability of the projection type liquid crystal display device can be further increased. .

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) H04N 5/74 H04N 5/74 K

Claims (4)

[Claims] 1. A projection type liquid crystal display device comprising a light source, a light separation optical system, a liquid crystal light valve, a photosynthesis optical system, a projection optical system, and a cooling device for cooling the liquid crystal light valve. 3. A projection type liquid crystal display device, wherein a glass plate is attached to a polarizing plate disposed on a light incident side and a light exit side of the liquid crystal display. 2. The liquid crystal light valve according to claim 1, wherein the glass plate to be attached to the polarizing plate is arranged such that the light incident side and the light emitting side of the liquid crystal light valve are on the liquid crystal light valve side. The projection type liquid crystal display device according to claim 1, wherein 3. The projection type liquid crystal display device according to claim 1, wherein said glass plate is attached to both sides of said polarizing plate. 4. The glass plate according to claim 1, wherein a glass plate having an anti-reflection film deposited on one surface is used as the glass plate, and a non-deposited surface is attached to the polarizing plate. Projection type liquid crystal display device.