JP2008009455A - Liquid crystal projector - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a liquid crystal projector that is free from display unevenness and is bright. <P>SOLUTION: The liquid crystal projector is provided with a power source, a first polarizing plate, a liquid crystal light valve, a second polarizing plate and a projecting means, wherein all glass molded articles, through which light transmitted through the first polarizing plate reaches the second polarizing plate are made of glass of low coefficient of linear expansion having 10×10<SP>-7</SP>/°C or lower for the absolute value of the average coefficient of linear expansion. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a liquid crystal projector.

Recent liquid crystal projectors respond to the voices of users who desire a brighter display and use powerful lamps such as ultra-high pressure mercury lamps and metal halide lamps as light sources.
However, such a high-brightness liquid crystal projector has a problem in that unevenness of contrast and unevenness of color occur around the projection screen after a while after lighting. This is considered to be caused by the fact that the polarizing plate and the black mask of the liquid crystal light valve absorb strong light and generate heat, and the liquid crystal light valve becomes hot. Therefore, in conventional liquid crystal projectors, as disclosed in JP-A-62-109024 and JP-A-10-48590, a polarizing plate as a heat source is installed away from the liquid crystal light valve, or a fan is installed. It was devised so that the temperature of the liquid crystal light valve would not rise by using forced ventilation.

In addition, in JP-A-10-39138 and JP-A-10-48590, glass recommended for supporting a polarizing plate is soda glass (average linear expansion coefficient = 81 to 92 × 10 ⁻⁷ / ° C.), Borosilicate glass (average linear expansion coefficient = 32 to 65 × 10 ⁻⁷ / ° C.), crown glass (average linear expansion coefficient≈90 × 10 ⁻⁷ / ° C.) and the like.

  However, even if it is configured as described above and the temperature rise of the liquid crystal light valve is suppressed, the conventional liquid crystal projector cannot sufficiently eliminate the display unevenness.

  As a result of analysis of the cause, it was found that there was another major factor besides display unevenness due to temperature unevenness of the liquid crystal light valve. That is, a small phase difference is generated in the glass constituting the liquid crystal light valve and the glass supporting the polarizing plate. This phase difference converts linearly polarized light into elliptically polarized light and causes unevenness in contrast and brightness. The reason why the phase difference occurs in the glass is as follows. That is, there is a distribution in the intensity of light irradiated on the glass. Usually, the light applied to the central part is strong and the light applied to the peripheral part is weak. In addition, there is a region where light does not hit the periphery of the glass. Then, the temperature of the glass varies depending on the location, and the degree of thermal expansion varies, resulting in distortion. When the glass is in contact with another object having different thermal expansion, the distortion is further increased. This distortion causes a phase difference due to the photoelastic effect.

  Accordingly, in the present invention, a bright liquid crystal projector having no display unevenness and excellent light resistance is provided by devising so that a phase difference does not occur even when strong light is irradiated onto the glass on the optical path of the liquid crystal projector. With the goal.

  Means taken by the present invention to solve the above problems are as follows.

The liquid crystal projector according to claim 1, wherein at least a light source, a first polarizing plate that absorbs a specific polarization component of light emitted from the light source, a liquid crystal light valve that modulates light transmitted through the first polarizing plate, A liquid crystal projector comprising: a second polarizing plate that absorbs a specific polarization component of light transmitted through the liquid crystal light valve; and a projection unit that projects the light transmitted through the second polarizing plate. All the glass molded articles that transmit the light transmitted through the plate before reaching the second polarizing plate are made of low expansion glass having an absolute value of an average linear expansion coefficient of 10 × 10 ⁻⁷ / ° C. or less. It is characterized by that.

  Examples of the glass molded product include a support glass for a polarizing plate, a dust-proof glass, a microlens array substrate, and a lens in addition to the upper and lower substrates of the liquid crystal cell.

The average coefficient of linear expansion refers to the average coefficient of linear expansion per 1 ° C. from 0 ° C. to 300 ° C. as defined in JIS R 3102-1978 “Test Method for Average Coefficient of Linear Expansion of Glass”. In general, it is known that glass or crystallized glass having a large SiO ₂ content has a small average linear expansion coefficient. Examples of the glass having an average linear expansion coefficient in the above range include quartz glass, 7913 95% silicate glass manufactured by Corning, and Neoceram (registered trademark) N-0 manufactured by Nippon Electric Glass. According to the above configuration, there is an effect that even if the glass has some temperature unevenness, a large distortion, that is, a large phase difference does not occur, so that contrast unevenness hardly occurs. More preferably, it is desirable to use a glass having an absolute value of an average linear expansion coefficient of 3 × 10 ⁻⁷ / ° C. or less. An example of such glass is Corning 7971 titanium silicate glass. With such a configuration, even if there is a large temperature unevenness in the glass, there is almost no distortion, that is, a large phase difference does not occur.

The liquid crystal projector according to claim 2, further comprising a polarization conversion device that converts natural light into polarized light on an optical path between the light source and the first polarization plate, and light transmitted through the polarization conversion device reaches the first polarization plate. All the glass molded articles that permeate until now are made of low expansion glass having an absolute value of an average linear expansion coefficient of 10 × 10 ⁻⁷ / ° C. or less.

  The polarization converter includes a glass plate inclined by a Brewster angle as disclosed in JP-A-10-48590, a polarization beam splitter and a lens as disclosed in JP-A-8-304739, a lens, and λ. / 2 refers to a device that combines plates, and has the function of converting natural light into polarized light with almost no light absorption. Examples of the glass molded product that transmits the light transmitted through the polarization conversion device before reaching the first polarizing plate include a lens, a dichroic mirror, a supporting glass for the polarizing plate, a color filter, and a reflection mirror. However, the reflection mirror has an effect of using low expansion glass only when light is reflected through the substrate glass. Note that even if a phase difference occurs before the first polarizing plate, the contrast does not become uneven as in the case of the phase difference between the first polarizing plate and the second polarizing plate, but the brightness and color become uneven. According to the above configuration, even if there is some temperature unevenness in the glass, a large distortion, that is, a large phase difference does not occur, and thus there is an effect that such brightness and color unevenness hardly occur.

The liquid crystal projector according to claim 3, wherein at least one polarization-dependent element is provided on an optical path between the second polarizing plate and the projection unit, and light transmitted through the second polarizing plate is applied to the last polarization-dependent element. All glass molded articles that pass through before reaching are characterized by being made of low expansion glass having an absolute value of an average linear expansion coefficient of 10 × 10 ⁻⁷ / ° C. or less. A polarization-dependent element is an element having different characteristics depending on polarization, and includes, for example, a dichroic mirror, a dichroic prism, a polarization beam splitter, a polarizing plate, and the like. Examples of the glass molded product that transmits the light transmitted through the second polarizing plate before reaching the polarization-dependent element include a lens, a dichroic mirror, a dichroic prism, a polarizing plate supporting glass, a color filter, and a reflection mirror. When there are a plurality of polarization-dependent elements, it is necessary that the glass molded product until reaching the last polarization-dependent element is a low expansion glass. In addition, when glass exists from when light reaches the last polarization-dependent element until it reaches the polarization-dependent portion of the polarization-dependent element, the glass needs to be low-expansion glass. In addition, even if a phase difference occurs after the second polarizing plate, the contrast and the unevenness of the brightness and the color are not caused as in the case of the phase difference between the first polarizing plate and the second polarizing plate. According to the above configuration, even if there is some temperature unevenness in the glass, a large distortion, that is, a large phase difference does not occur, and thus there is an effect that such brightness and color unevenness hardly occur.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

(Embodiment 1)
FIG. 1 is a diagram showing the overall structure of a liquid crystal projector which is an embodiment of the invention according to claim 1.

  The structure and function will be described with reference to the drawings. In FIG. 1, light emitted from the light source lamp unit 101 passes through a uniform illumination & polarization conversion optical system 102 including an integrator lens and a polarization separation prism array, and becomes uniform linearly polarized light. Next, the light is bent at a right angle by the reflection mirror 103 and separated into red, green, and blue light beams by the blue-green reflection dichroic mirror 105 and the green reflection dichroic mirror 107 via the lens 104. Thereafter, the light is guided to the condenser lens 112, the first polarizing plate 113, the liquid crystal light valve 114, and the second polarizing plate 115 for each color by the reflection mirrors 106, 109, and 111 and the lenses 108 and 110, and an image is formed. . The formed image of each color is combined with a color image by the dichroic prism 116 and enlarged and projected onto the screen 118 via the projection lens unit 117.

  The structure of the portion where image formation for each color is performed will be described in more detail with reference to the drawings. 2A, 201 is a condenser lens, 202 is a first polarizing plate, 203 is a supporting glass for the first polarizing plate, 204 is a first dustproof glass, 205 is a supporting glass for a microlens array, and 206 is a microlens. Array, 207 is a cover lens of a microlens array, 208 is a liquid crystal layer, 209 is a substrate of a liquid crystal light valve, 210 is a second dustproof glass, 211 is a supporting glass for the second polarizing plate, 212 is a second polarizing plate, 213 is It is a dichroic prism. This figure shows the structure of a portion that forms green light, but the portion that forms an image of blue light and red light has basically the same structure. Light enters from the left and exits to the right. The microlens array is disclosed in detail in Japanese Patent Laid-Open Nos. 3-248125, 7-225303, and 7-181305. The dust-proof glass is a glass for preventing dust adhering to the surface of the liquid crystal light valve from appearing in the projected image by sufficiently separating it from the focus surface. On the substrate of the liquid crystal light valve, vertical and horizontal wirings, a TFT array, a liquid crystal driver, an alignment film, and the like are arranged, but are omitted in this figure. The members 204 to 210 are bonded to each other.

  When the liquid crystal projector is turned on, a phase difference occurs in each glass with time. FIG. 3A shows the direction and magnitude of the phase difference generated in the supporting glass of the second polarizing plate by an arrow 301 as an example. There is a slow axis in the tangential direction of an ellipse that is generally centered on the center of the glass, and the phase difference is larger as it is closer to the periphery than the center. FIG. 3B shows the brightness distribution when the supporting glass of the polarizing plate in which the phase difference has occurred is sandwiched between the orthogonal polarizing plates. The central portion is dark and the four corners 302 are bright. The reason for the abnormality appearing at the four corners, not the entire periphery is that the direction of the phase difference and the direction of the polarizing plate are perpendicular / parallel at the four sides. Depending on the arrangement method of the polarizing plate, there are cases where the four corners are normal and the four sides are abnormal. Also in the projected image of the liquid crystal projector, the same abnormality occurs particularly in black display, so the contrast in the peripheral part (four corners) is lowered.

Each glass molded product positioned between the first polarizing plate and the second polarizing plate, that is, the supporting glass 203 of the first polarizing plate, the first dustproof glass 204, the supporting glass 205 of the microlens array, the cover glass 207 of the microlens array, the liquid crystal The following experiment was performed on the light valve substrate 209, the second dustproof glass 210, and the support glass 211 of the second polarizing plate. These glass molded articles were made into four types of glass materials, namely 7971 titanium silicate glass (average linear expansion coefficient = 0.3 × 10 ⁻⁷ / ° C.), quartz glass (average linear expansion coefficient = 5.5 × 10 ⁻ ) manufactured by Corning. ⁷ / ° C.), Pyrex (registered trademark) (average linear expansion coefficient = 32.5 × 10 ⁻⁷ / ° C.), and soda glass (average linear expansion coefficient = 81 × 10 ⁻⁷ / ° C.). These were irradiated with light for 1 minute in the liquid crystal projector, and immediately sandwiched between orthogonal polarizing plates to observe uneven brightness as shown in FIG. 3B, and the transmittance in the brightest region was measured. Regarding the members that cannot be measured alone because they are bonded, the measurement was performed using 7971 titanium silicate glass manufactured by Corning, which has almost zero average linear expansion coefficient, as the glass other than the target member. The results are shown in Table 1.

  The member causing the largest unevenness is the supporting glass of both polarizing plates, and then dust-proof glass. The former is because the heat generation of the polarizing plate causes large temperature unevenness in the glass, and the latter is because the glass is thick, so that even if the thermal strain is the same, a large phase difference is caused. On the other hand, the member that hardly causes unevenness is a cover glass of a microlens array because of its thinness of 50 μm.

  Next, a 0.7 mm-thick glass plate having various average linear expansion coefficients is used as the supporting glass for the second polarizing plate 211, light is irradiated for 1 minute in the liquid crystal projector, and the glass is immediately applied to the orthogonal polarizing plate. The brightness non-uniformity was observed across the light and the transmittance of the brightest region was measured. The result is shown in FIG.

  In FIG. 4, the horizontal axis represents the average linear expansion coefficient, and the vertical axis represents the leakage light transmittance normalized by the transmittance of the glass and the polarizing plate. From this experimental result, it is clear that the smaller the absolute value of the average linear expansion coefficient, the smaller the transmittance and the less the unevenness. The average linear expansion coefficient has a positive value in most cases (that is, it extends when warmed), but even if it is a negative value, the smaller the absolute value, the smaller the transmittance, which is more preferable. There is some variation in the experimental results. Most of them are experimental errors, but it is thought that other factors such as thermal conductivity and photoelasticity are different depending on the glass. However, it is also clear from the figure that the factor that most affects the transmittance of leaked light is the average linear expansion coefficient.

In order to achieve the contrast of 1: 1000 required for a liquid crystal projector, at least the transmittance must be suppressed to 0.1% or less. Therefore, it is necessary to use a glass having an absolute value of an average linear expansion coefficient of 10 × 10 ⁻⁷ / ° C. or less. As shown in Table 1, since other glasses also cause light leakage, the absolute value of the average linear expansion coefficient is 3 × 10 ^{−7 for a} glass molded product that is likely to cause a phase difference with a margin. It is desirable to use a glass of / ° C. or lower.

Examples of the glass having an absolute value of an average linear expansion coefficient of 10 × 10 ⁻⁷ / ° C. or less include quartz glass (5.5 × 10 ⁻⁷ / ° C.) and 7913 95% silicate glass (7. 5 × 10 ⁻⁷ / ° C.), Neoceram (registered trademark) N-0 (−6 × 10 ⁻⁷ / ° C.) of Nippon Electric Glass. Examples of the glass having an absolute value of an average linear expansion coefficient of 3 × 10 ⁻⁷ / ° C. or less include 7971 titanium silicate glass (0.3 × 10 ⁻⁷ / ° C.) manufactured by Corning.

  Using these low expansion glasses, each glass molded product located between the first polarizing plate and the second polarizing plate, that is, the supporting glass 203 of the first polarizing plate, the first dustproof glass 204, the supporting glass 205 of the microlens array, When the cover glass 207 of the microlens array, the substrate 209 of the liquid crystal light valve, the second dustproof glass 210, and the support glass 211 of the second polarizing plate were created, the reduction in contrast at the peripheral portion was improved to such an extent that it could not be visually recognized. .

In addition, since the supporting glass of the polarizing plate tends to generate a large phase difference, it is desirable to adopt the configuration of FIG. 2B in which the polarizing plate faces the liquid crystal light valve side. If comprised in this way, the phase difference of the support glass of a polarizing plate will not be connected directly to unevenness of contrast.
On the other hand, uneven brightness may occur, but details thereof will be described in the following embodiments.

(Embodiment 2)
Next, a liquid crystal projector which is an embodiment of the invention according to claim 2 will be described. The overall structure of the liquid crystal projector according to this embodiment is as already described with reference to FIG. However, the liquid crystal projector according to the present embodiment is different from that of the first embodiment described above in the structure of the polarizing plate and the supporting glass.

  FIG. 2B is a detailed view of the structure of the portion where image formation for each color is performed. In FIG. 2B, 201 is a condensing lens, 203 is a supporting glass for a first polarizing plate, 202 is a first polarizing plate, 204 is a first dustproof glass, 205 is a supporting glass for a microlens array, and 206 is a microlens. Array, 207 is a cover lens of a microlens array, 208 is a liquid crystal layer, 209 is a substrate of a liquid crystal light valve, 210 is a second dustproof glass, 212 is a second polarizing plate, 211 is a supporting glass for the second polarizing plate, 213 It is a dichroic prism. The positional relationship between the polarizing plate and the supporting glass is opposite to that in FIG. 2A of Example 1, and the polarizing plate is located on the liquid crystal light valve side.

When the liquid crystal projector is turned on, a phase difference occurs in each glass with time. FIG. 3A shows the direction and magnitude of the phase difference generated in the supporting glass of the second polarizing plate by an arrow 301 as an example. There is a slow axis generally in the tangential direction of a circle centered on the center of the glass, and the phase difference is larger in the peripheral part than in the central part.
FIG. 3B shows the brightness distribution when the supporting glass of the polarizing plate in which the phase difference has occurred is sandwiched between the orthogonal polarizing plates. The central portion is dark and the four corners 302 are bright. In the projection image of the liquid crystal projector, uneven brightness and uneven color occur substantially corresponding to the phase difference distribution of FIG.

  Each glass molded product positioned between the polarization conversion device and the first polarizing plate, that is, the reflection mirror 103, the lens 104, the blue-green reflection dichroic mirror 105, the green reflection dichroic mirror 107, the lens 108, the lens 110, the lens 112 (201), the first The following experiment was conducted on the supporting glass 203 of one polarizing plate. These glass molded articles are made of four kinds of glass materials, that is, 7971 titanium silicate glass, quartz glass, Pyrex (registered trademark), and soda glass manufactured by Corning. These were irradiated with light for 1 minute in the liquid crystal projector, and immediately sandwiched between orthogonal polarizing plates to observe uneven brightness as shown in FIG. 3B, and the transmittance in the brightest region was measured. The results are shown in Table 2.

The member that causes the largest unevenness is the supporting glass of the first polarizing plate, and then the lens 112. The former is because heat generation of the polarizing plate causes large temperature unevenness of the glass, and the latter is close to the polarizing plate, and because the glass is thick, a large phase difference is caused even if the same thermal strain is caused. On the other hand, the member that hardly causes unevenness is the dichroic mirror because it is far from the heat source and is thin. In Pyrex (registered trademark) and soda glass having an average linear expansion coefficient larger than 10 × 10 ⁻⁷ / ° C., light leakage occurs somewhat, but in Corning 7971 titanium silicate glass and quartz glass, light leakage occurs. Was found to be almost completely suppressed.

  Therefore, using 7971 titanium silicate glass or quartz glass, each glass molded product located between the polarization conversion device and the first polarizing plate, that is, the reflection mirror 103, the lens 104, the blue-green reflection dichroic mirror 105, the green reflection dichroic mirror 107, When the lens 108, the lens 110, the lens 112 (201), and the support glass 203 of the first polarizing plate were produced, the brightness unevenness and the color unevenness in the peripheral portion were improved to such an extent that they could not be visually recognized.

  In Example 2, the reflection mirror was included in “all glass molded products that transmitted before the light transmitted through the polarization conversion device reaches the first polarizing plate” in claim 2. This is because a reflection mirror having the structure shown in FIG. In FIG. 5A, 501 is a glass plate and 502 is a specular reflection layer. Since light passes through the glass plate, is reflected by the specular reflection layer, and passes through the glass plate again, the phase difference generated in the glass plate affects the display. If no problem such as fogging occurs on the surface of the specular reflection layer, the structure in which the reflection is performed by the specular reflection layer 502 without passing through the glass plate 501, as shown in FIG. Desirable from a viewpoint.

(Embodiment 3)
Next, a liquid crystal projector which is an embodiment of the invention according to claim 3 will be described. The overall structure of the liquid crystal projector is as already described with reference to FIG. However, the liquid crystal projector according to the present embodiment is different from the first embodiment in the structure of the polarizing plate and its supporting glass, and as shown in FIG. 2B, the polarizing plate is closer to the liquid crystal light valve than the supporting glass. The point located in is a feature.

When the liquid crystal projector is turned on, a phase difference occurs in each glass with time. FIG. 3A shows the direction and magnitude of the phase difference generated in the supporting glass of the second polarizing plate by an arrow 301 as an example. There is a slow axis generally in the tangential direction of a circle centered on the center of the glass, and the phase difference is larger in the peripheral part than in the central part.
FIG. 3B shows the brightness distribution when the supporting glass of the polarizing plate in which the phase difference has occurred is sandwiched between the orthogonal polarizing plates. The central portion is dark and the four corners 302 are bright. In the projection image of the liquid crystal projector, uneven brightness and uneven color occur substantially corresponding to the phase difference distribution of FIG.

  Each glass molded product located between the second polarizing plate and the dichroic prism, that is, the supporting glass 211 of the second polarizing plate, and the portion of the glass until reaching the interference layer of the dichroic prism 213 (116) are as follows. The experiment was conducted. These glass molded articles are made of four kinds of glass materials, that is, 7971 titanium silicate glass, quartz glass, Pyrex (registered trademark), and soda glass manufactured by Corning. These were irradiated with light for 1 minute in the liquid crystal projector, and immediately sandwiched between orthogonal polarizing plates to observe uneven brightness as shown in FIG. 3B, and the transmittance in the brightest region was measured. The results are shown in Table 3.

The member causing the largest unevenness is a dichroic prism, and then the supporting glass of the second polarizing plate. The former is because the glass is thick, so that even if the thermal strain is the same, a large phase difference is caused. The latter is because the heat generation of the polarizing plate causes a large temperature unevenness of the glass. In Pyrex (registered trademark) and soda glass having an average linear expansion coefficient larger than 10 × 10 ⁻⁷ / ° C., light leakage occurs somewhat, but in Corning 7971 titanium silicate glass and quartz glass, light leakage occurs. It was found that can be almost suppressed.

  Therefore, using 7971 titanium silicate glass or quartz glass, each glass molded product located between the second polarizing plate and the dichroic prism, that is, the supporting glass 211 of the second polarizing plate, and the dichroic prism 213 are prepared. The brightness unevenness and color unevenness of the part were improved to such an extent that they could not be recognized visually. In particular, when 7971 titanium silicate glass was used, there was no unevenness due to the glass.

  As described above, according to the present invention, a bright liquid crystal projector with small display unevenness can be provided by devising so that a phase difference does not occur even when strong light is irradiated onto the glass on the optical path of the liquid crystal projector. be able to.

It is a figure which shows the whole structure of the liquid crystal projector in Embodiment 1 thru | or Embodiment 3 of this invention. (A) It is a figure which shows the structure of the part in which the image formation of the liquid crystal projector in Embodiment 1 of this invention is performed. (B) It is a figure which shows the structure of the part in which the image formation of the liquid crystal projector in Embodiment 2 and Embodiment 3 of this invention is performed. (A) In the liquid crystal projector in Embodiment 1 thru | or Embodiment 3 of this invention, it is a figure which shows the direction and magnitude | size of phase difference which generate | occur | produce in the support glass of a polarizing plate. (B) It is a figure which shows the brightness distribution at the time of pinching the support glass of the polarizing plate in which the said phase difference generate | occur | produced between the orthogonal polarizing plates. It is a figure explaining the experimental result in Embodiment 1 of this invention, and is a figure which shows the relationship between the average linear expansion coefficient of the glass of a polarizing plate with glass, and the transmittance | permeability of leakage light. It is a figure which shows the structure of the reflective mirror used with the liquid crystal projector in Embodiment 2 of this invention.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 101 ... Light source lamp unit, 102 ... Uniform illumination & polarization conversion optical system, 103 ... Reflection mirror, 104 ... Lens, 105 ... Blue-green reflection dichroic mirror, 106 ... Reflection mirror, 107 ... Green reflection dichroic mirror, 108 ... Lens, 109 DESCRIPTION OF SYMBOLS ... Reflection mirror, 110 ... Lens, 111 ... Reflection mirror, 112 ... Condensing lens, 113 ... First polarizing plate, 114 ... Liquid crystal light valve, 115 ... Second polarizing plate, 116 ... Dichroic prism, 117 ... Projection lens unit, DESCRIPTION OF SYMBOLS 118 ... Screen, 201 ... Condensing lens, 202 ... 1st polarizing plate, 203 ... Support glass of 1st polarizing plate, 204 ... 1st dustproof glass, 205 ... Support glass of microlens array, 206 ... Microlens array, 207 ... Microlens array cover glass, 208 ... Liquid crystal layer, 209 ... Substrate crystal light valve, 210 ... second dustproof glass, 211 ... supporting glass of the second polarizing plate, 212 ... second polarizing plate, 213 ... dichroic prism.

Claims (3)

A light source, a first polarizing plate that absorbs a specific polarization component of light emitted from the light source, a liquid crystal light valve that modulates light transmitted through the first polarizing plate, and identification of light transmitted through the liquid crystal light valve A liquid crystal projector comprising: a second polarizing plate that absorbs the polarized light component; and a projection unit that projects light transmitted through the second polarizing plate, wherein the light transmitted through the first polarizing plate is the second polarized light. A liquid crystal projector, characterized in that all glass molded articles that pass through before reaching a plate are made of low expansion glass having an absolute value of an average linear expansion coefficient of 10 × 10 ⁻⁷ / ° C. or less. All glass molded articles comprising a polarization conversion device that converts natural light into polarized light on the optical path between the light source and the first polarizing plate, and the light transmitted through the polarization conversion device is transmitted before reaching the first polarizing plate 2. The liquid crystal projector according to claim 1, wherein the liquid crystal projector is made of a low expansion glass having an absolute value of an average linear expansion coefficient of 10 × 10 ⁻⁷ / ° C. or less. All glasses that provide at least one polarization-dependent element on the optical path between the second polarizing plate and the projection means, and transmit the light transmitted through the second polarizing plate before reaching the last polarization-dependent element 3. The liquid crystal projector according to claim 1, wherein the molded article is made of low expansion glass having an average linear expansion coefficient of 10 × 10 ⁻⁷ / ° C. or less.

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