JP2002116502A - Projection type display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an inexpensive projection type display device having simple constitution by which a projected image having excellent contrast can be always obtained without being influenced by heat generation and the change of ambient temperature or the like. SOLUTION: This display device is provided with polarized light separation optical systems 102, 103 and (108) for polarizing and separating a light beam from a light source 101, reflection type light valves 107R, 107G and 107B arranged at positions on which the light beams polarized and separated by the optical systems 102, 103 and (108) are made incident, and modulating and emitting the incident light beams, and an analyzer optical system 103 analyzing the light beams emitted from the light valves 107R or the like. In the device, at least either the optical systems 102, 103 and (108) or the optical systems 103 and 108 include a polarizing film member 1082 having characteristic that a specified linearly polarized light beam out of the incident light beams is emitted and the light beam other than the specified linearly polarized light beam is absorbed, and the member 1082 is held between heat resistant optical members 1081a and 1081b.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a projection display device for detecting light emitted from a light valve and projecting the light on a screen by a projection lens.

[0002]

2. Description of the Related Art An example of the configuration of a conventional projection display device will be described. First, substantially parallel light from a light source is polarized and separated by a polarizing beam splitter. Next, the polarized light is incident on the reflection type light valve. The reflection type light valve modulates and emits incident light. The reflected light modulated by the reflection type light valve again enters the polarization beam splitter and is analyzed. Finally, the analysis light emitted from the polarization beam splitter is projected on a screen via a projection lens.

[0003]

In order to improve the contrast of a projected image in the above-mentioned prior art, it is necessary to perform polarization separation with high precision or perform analysis with high precision. For this purpose, a polarizing film is disposed between the light source and the polarizing beam splitter, or between the polarizing beam splitter and the projection lens.

[0004] The operation of the polarizing film will be described. The polarizing film disposed between the light source and the polarizing beam splitter has a function of converting non-polarized (randomly polarized) light source light into predetermined polarized light.

[0005] A polarizing film disposed between the polarizing beam splitter and the projection lens has a function of polarizing the detection light. The analysis light from the polarization beam splitter is not completely polarized light but a mixed light including unnecessary light due to the polarization separation performance of the polarization beam splitter. Unwanted light causes a decrease in the contrast of the projected image. The polarizing film disposed between the polarizing beam splitter and the projection lens can remove the unnecessary light almost completely.

When these polarizing films are used, unnecessary light, that is, light other than transmitted light, is absorbed by the polarizing film.
Then, thermal deformation occurs in the polarizing film due to light absorption. Due to this thermal deformation, the molecular arrangement of the members constituting the polarizing film is disturbed, so that the polarization separating function is reduced. Therefore, it causes deterioration of the projected image. Note that the deterioration of the projected image refers to a decrease in contrast or the like.

Further, the deformation of the polarizing film due to heat is as follows:
It also occurs due to an increase in ambient temperature near the position where the polarizing film is disposed. In particular, when the polarizing film is disposed between the light source and the polarizing beam splitter, the ambient temperature significantly increases due to light emission from the light source. Such thermal deformation caused by an increase in the environmental temperature also deteriorates the polarization separation function similarly to the thermal deformation due to the light absorption, and thus causes deterioration of a projected image.

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and it is possible to obtain a projection image which is inexpensive, has a simple configuration, and always has good contrast, without being affected by heat generation, changes in environmental temperature, and the like. It is an object of the present invention to provide a projection-type display device that can perform the above-described operations.

[0009]

Means for solving the above problems will be described with reference to the accompanying drawings showing an embodiment. The present invention relates to a polarization separating optical system for polarizing and separating light from a light source 101. 102, 103, and (108), and reflection-type light valves 107R and 107G that are arranged at positions where light polarized and separated by the polarization separation optical systems 102, 103, and (108) is incident, and modulates and emits the incident light. , 1
07B and the reflective light valves 107R, 107
G, an optical analysis system 1 for analyzing light emitted from 107B
03, 108, at least one of the polarization separation optical system 103 and the analysis optical system 103 emits specific linearly polarized light out of the incident light and absorbs light other than the specific linearly polarized light. The polarizing film member 1082
Reference numeral 2 provides a projection display device characterized by being sandwiched between heat-resistant optical members 1081a and 1081b.

According to a preferred aspect of the present invention, the polarization splitting optical system 102, 103, (108) and the analysis optical system 103, 108 are connected to the polarization splitting optical system 10
2, 103, (108) and the analysis optical systems 103, 10
8 is a common polarizing beam splitter 10 that also has the function of
3, the heat-resistant optical members 1081a and 1081 are provided on the emission side of the analysis light of the polarization beam splitter 103.
b, and the incident surface 1084a and the outgoing surface 1084b of the analysis light of the heat resistant optical members 1081a and 1081b are flat-polished after the polarizing film member 1082 is sandwiched. Surface is desirable.

According to a preferred embodiment of the present invention, the polarization splitting optical systems 102, 103, and (108) and the analysis optical system 103 are connected to the polarization splitting optical systems 102, 10 and 10, respectively.
3, (108) and a common polarizing beam splitter 103 also serving as the analysis optical system 103. The polarizing beam splitter 103 is sandwiched between the heat resistant optical members 1081a and 1081b on the light source 101 side. It is preferable that the polarizing film member 1082 is provided.

According to a preferred embodiment of the present invention, it is preferable that the light incident surface 1084a of the heat resistant optical members 1081a and 1081b has an antireflection film AR.

In the section of the means for solving the above-mentioned problems, which explains the configuration of the present invention, the drawings of the embodiments of the present invention are used to make the present invention easy to understand. However, the present invention is not limited to this.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a projection type display device according to an embodiment will be described with reference to the accompanying drawings.

(First Embodiment) FIG. 1 is a diagram showing a schematic configuration of a projection type display device according to a first embodiment. A light source 101 including a lamp LP and a parabolic mirror PM emits light from a light source. The light from the light source passes through the infrared cut filter IRF and the ultraviolet cut filter UVF, and then enters the polarization converter 10.
2 is incident. The polarization converter 102 converts the randomly polarized light into P-polarized light.

FIG. 2 is a diagram showing a configuration of the polarization conversion device 102. The polarization conversion device 102 includes a first lens plate 1021 and a second lens plate 1022 in order from the light source 101 side.
, A polarizing beam splitter array 1023, and a condenser lens 1024. First lens plate 10
Reference numeral 21 denotes a plurality of lens elements 1021a arranged in a plane. The second lens plate 1022 has a plurality of lens elements 1022a arranged in a plane corresponding to the lens elements 1021a. The polarization beam splitter array 1023 includes a plurality of polarization beam splitter elements 1023.
a, 1023b are arranged so that the polarized light separating units PD are parallel to each other. Here, a half-wave plate WP is provided on the exit surface of the predetermined polarization beam splitter element 1023b. Then, the polarizing beam splitter array 1
A condenser lens 1024 is provided on the exit side of the reference numeral 23.

In the polarization converter 102 having this configuration, the first
The light from the light source incident on the lens plate 1021 is
The light is split into a plurality of lights defined by the outer shape of 21a. The split light is collected on a lens element 1022a arranged corresponding to each lens element 1021a. Then, a bright spot is formed on each of the lens elements 1022a.

The light emitted from the bright spot enters the polarizing beam splitter array 1023. This incident light is
The light is split into P-polarized light transmitted through the polarization beam splitter element 1023a and S-polarized light reflected by the polarization splitter PD. The S-polarized light reflected by the polarization splitter PD enters another adjacent polarization beam splitter element 1023b. Then, the other polarization beam splitter element 102
The light is reflected by the polarization separation unit PD 3b and emitted. A 波長 wavelength plate WP is provided on the S-polarized light exit surface. Therefore, the S-polarized light is converted into P-polarized light by the half-wave plate WP and emitted. Therefore, the light exiting the polarization converter 102 is converted into P-polarized light as a whole. The P-polarized light travels through the condenser lens 1024 toward the polarization beam splitter 103.

The polarization beam splitter 103 is composed of a prism 103A having a triangular prism shape, a prism 103B, and a polarization separation section 103p formed on a joint surface between the two prisms. The polarization splitting unit 103p includes the polarization conversion device 102
Is split into P-polarized light that passes through the polarization splitting unit 103p and S-polarized light that reflects. The transmitted P-polarized light exits the polarization beam splitter 103. Since the incident light is P-polarized light, the polarization beam splitter 103 substantially transmits and emits most of the light. In addition, it also has a function of reflecting and discarding the S-polarized component remaining in the incident light, which cannot be polarization-converted by the polarization converter 102.

The prism 104 and the prism 10
5. The light enters a color separation / combination prism composed of a prism 106 and a plurality of dichroic films formed on a predetermined surface of the prism. Unnecessary S-polarized light reflected by the polarization separation unit 103p travels with the optical path bent at 90 degrees and is discarded.

Next, the color separation / synthesis prism converts the light from the light source into R light.
A configuration for performing color separation into light, G light, and B light will be described.
As described above, the color separation / combination prism is
4, a prism 105 and a prism 106.

First, the prism 104 for extracting the B light component from the light source light will be described.

The prism 104 has a first surface 104a and a second surface 104a.
It has a surface 104b and a third surface 104c. First side 1
04a receives light from a light source. The second surface 104b has a B light reflecting dichroic film DB that reflects B light and transmits R light and G light. The third surface 104c is the second surface 10c.
4b, and then emits B light totally reflected on the first surface 104a. With this configuration, the prism 104
The B light component of the light from 01 can be extracted.

Then, the B light emitted from the third surface 104c enters the light valve 107B for B light.

Next, the prism 105 for extracting the R light component from the light source light will be described. The prism 105
It is provided with a gap from the second surface 104b of the prism 104. The prism 105 has a first surface 105a, a second surface 105b, and a third surface 105c. First surface 10
5a receives the light transmitted through the second surface 104b of the prism 104. The second surface 105b has an R light reflecting dichroic film DR that reflects R light and transmits G light. Third
The surface 105c reflects the second surface 105b and then the first surface 1
The R light which totally reflects 05a is emitted. With this configuration,
The prism 105 can extract the R light component of the light from the light source 101.

Then, the R light emitted from the third surface 105c enters the R light light valve 107R.

Next, the prism 106 for extracting the G light component from the light source light will be described. The prism 106
The first surface 106a is the second surface 105 of the prism 105.
b is fixed by an adhesive.

The prism 106 has a first surface 106a and a second surface 106a.
It has a surface 106b and a third surface 106c. First side 1
06a receives the light transmitted through the second surface 105b of the prism 105. The second surface 106b totally reflects the G light. The third surface 106c emits the G light totally reflected on the second surface 106b. With this configuration, the prism 106
The G light component of the light from 1 can be extracted.

Then, the G light emitted from the third surface 106c enters the G light light valve 107G.

The above-described polarization beam splitter 10
3, prism 104, prism 105, prism 106
It is desirable to use glass having an absolute value of a photoelastic constant of 1.5 × 10 ⁻⁸ cm ² / N or less so that the polarization state of light passing through the inside does not change.

Next, the light valve will be described. The light valves 107B, 107G, and 107R are reflection-type liquid crystal light valves. The light valve has a plurality of pixels arranged in a matrix. Each pixel has a liquid crystal layer having liquid crystal molecules and a reflective layer provided on the back surface of the liquid crystal layer. The direction of the liquid crystal molecules can be changed by applying a voltage to the liquid crystal layer by changing the voltage value in the thickness direction of the liquid crystal layer by a switching element such as a TFT arranged for each pixel. Then, the inclination of the polarization of the light incident on the light valve changes according to the direction of the liquid crystal molecules. That is, the polarization state of the incident light can be modulated. In this way, the polarization state is changed by changing the applied voltage,
The gradation level of the image can be determined.

A pixel to which no voltage is applied to the liquid crystal layer of the light valve is a pixel having the lowest gradation level, that is, the darkest pixel. At this time, the liquid crystal molecules of the liquid crystal layer maintain the initial state. Reflected by the reflective layer via the liquid crystal layer in this state,
Light emitted again via the liquid crystal layer becomes non-modulated light that has not been subjected to a modulation action. Then, the unmodulated light re-enters the color separation / combination prism as P-polarized light.

The pixel to which the highest voltage is applied to the liquid crystal layer of the light valve is the pixel having the highest gradation level, that is, the brightest pixel. At this time, the liquid crystal layers are arranged in a predetermined direction away from the initial state, forming a wave plate layer. The light reflected by the reflective layer via the liquid crystal layer in this state and emitted again via the liquid crystal layer becomes modulated light which has undergone a modulation action. Then, the modulated light re-enters the color separation / combination prism as S-polarized light.

The color separation / combination prism combines the colors of the light reflected from the light valves 107R, 107G, and 107B. The color-combined light is analyzed by the polarization splitter 103p of the polarization beam splitter 103. Then, only the S-polarized light component, which is the light modulated by the light valve, passes through a polarizing device 108 described later, and then enters the projection lens 109.
The projection lens 109 projects the R, G, and B color light valve images on the screen SC as a full color image. The P-polarized light component, which is unmodulated light, travels straight through the polarization beam splitter 103p of the polarization beam splitter 103, is emitted toward the light source 101, and is discarded.

FIG. 3 is a diagram showing a schematic configuration of the polarizing device 108. The polarizing device 108 includes a polarizing film member 108.
2 are transparent glass plates 1081a and 1081
1b, the adhesive layers 1083a and 1083
3b, it is bonded and fixed. The polarizing film member has a characteristic of emitting only a specific linearly polarized light out of the incident light and absorbing a polarization component other than the specific linearly polarized light. It is desirable that the transparent glass plates 1081a and 1081b are parallel flat glass. However, the shape is not limited to this, and the surface 1084a and the surface 1084b may be wedge-shaped (so-called wedge-shaped) transparent glass having a mutual inclination of about 2 to 3 degrees. Further, the lens and the prism are made of a transparent glass plate 1081.
a, 1081b may be used instead. And
Analysis light incidence surface 1084a and analysis light emission surface 1084
b is plane-polished after the polarizing film member 1082 is sandwiched. In this planar polishing step, optical polishing is performed while paying attention to the parallelism and surface accuracy of both surfaces. For this reason, a projection image having good imaging characteristics can be obtained.

The polarizing film member 1082 is bonded to the adhesive layer 10
The following effects can be obtained by being sandwiched between the glass plates via 83a and 1083b. Polarizing film member 10
82 is generally made of resin. Therefore, when the polarizing film member 1082 is simply adhered to an optical member such as the polarizing beam splitter 103, the polarizing film member 1082
Unevenness occurs on the surface. This unevenness causes unnecessary refraction. Therefore, if the polarizing film member 1082 is simply adhered to the optical member between the projection lens 109 and the polarizing beam splitter 103, the projected image may be lost due to unnecessary refraction. The refractive indices of the adhesive and the polarizing film member 1082 are close values. Therefore, in the case of the polarizing device 108 of the present embodiment, the unnecessary refraction action described above is canceled by the adhesive entering the unevenness of the polarizing film member 1082.

The following effects can be obtained by polishing the transparent glass plates 1081a and 1081b after bonding the polarizing film member 1082 to the transparent glass plates 1081a and 1081b. When the polarizing film member 1082 is bonded to the transparent glass plates 1081a and 1081b, the transparent glass plates 1081a and 1081b undulate.
This undulation also causes unnecessary refraction. Then, the polarizing film member 1082 is connected to the transparent glass plate 1081a,
081b, the transparent glass plate 1081a,
Each of 1081b is polished. Then, the above-mentioned undulation is eliminated. Therefore, the polarizing device 1 that has been processed as described above.
The projection type display device employing No. 08 as an analysis optical system has an inexpensive configuration to improve contrast, but does not have an unnecessary refraction effect, so that a projected image is not seen.

Further, preferably, the incident surface 108 of the analysis light
4a and the emission surface 1084b of the analysis light are provided with an anti-reflection film AR
It is desirable to have The antireflection film AR is formed by a low-temperature evaporation method so that the flatness is not changed. The low-temperature deposition method refers to a polarizing film member 1082 and an adhesive 1083.
a, 1083b at a temperature that does not alter the quality of the anti-reflection film AR
Is referred to as a method of vapor deposition. For example, in a method using an ordinary evaporation pot, there are a method of performing plasma assist and a method of magnetron sputtering.

As described above, the incident surface 1084 of the analysis light
The following effects can be obtained by forming the anti-reflection film AR on a. Without the anti-reflection film AR, a part of the light incident from the polarization beam splitter 103 is reflected to the polarization beam splitter 103 side. This reflected light is re-reflected by the polarization beam splitter 103 and the like to become noise, and the contrast of the projected image is reduced. Further, if part of the light from the polarizing beam splitter 103 does not pass through the polarizing device 108, it causes a reduction in the brightness of the projected image. The inventor of the present application has assumed that the above-described problem will occur due to the insertion of the polarization device 108, and has decided to provide the antireflection film AR on the polarization device 108. Therefore, the anti-reflection film AR can reduce unnecessary noise and improve the contrast of a projected image. In the above-described embodiment, the polarizing film member 1082 is configured to be sandwiched between glass plates. However, the member sandwiching the polarizing film member 1082 is not limited to glass, and may be any heat-resistant optical material.

The heat resistance will be briefly described below.
When the polarizing film member 1082 performs polarization separation, heat is generated. This heat varies depending on the type of light source and the position where the polarizing film member 1082 is arranged, and is unique to the apparatus. The heat-resistant optical material may be a material whose optical performance does not change due to the heat generated by the polarizing film member 1082. For example, besides glass, there are polycarbonate and acrylic. In the above-described embodiment, the polarizing film member 1082 is sandwiched between glass plates, so that the polarizing device 108 is characterized by being less expensive than the polarizing beam splitter. The polarization beam splitter forms a polarization separation surface with a multilayer film. As a result, polarizing beam splitters are expensive to deposit,
It will be expensive. Therefore, if a large number of polarizing beam splitters are mounted, the price of the entire apparatus increases. On the other hand, the polarizing film member 1082 can be obtained at low cost. Therefore, the polarizing device 108 of the present embodiment
Is provided, an inexpensive device having good polarization separation performance is provided.

Returning to FIG. 1, the polarizing film member 1082 of the polarizing device 108 is arranged such that S-polarized light of incident light is transmitted and P-polarized light is absorbed by the polarizing film member 1082. Polarizing beam splitter 103
P-polarized light partially coexists in the light that travels by reflecting light due to imperfect polarization separation characteristics. This P-polarized component is absorbed by the polarizer 108. Therefore, the light transmitted through and emitted from the polarizing device 108 does not include unnecessary components. Therefore, a high-contrast full-color image can be projected on the screen SC.

In particular, in the polarizing device 108 of the present embodiment, the polarizing film 1082 is adhered and fixed from both sides via transparent glass plate members 1081a and 1081b, which are substantially parallel flat plates, with adhesive layers 1083a and 1083b. . For this reason, the polarizing film 1082 is not thermally deformed, and thus has the following two effects. The first effect is
The polarization of the analysis light can be favorably separated, so that the contrast of the projected image is improved. The second effect is that deterioration of the imaging performance caused by deformation of the polarizing film 1082 is prevented.

(Second Embodiment) FIG. 4 is a diagram showing a schematic configuration of a projection display apparatus according to a second embodiment. The basic configuration of this embodiment is almost the same as that of the first embodiment. Therefore, the same reference numerals are used for the same portions, and duplicate description will be omitted. In the first embodiment, the polarizing device 10 is disposed between the polarizing beam splitter 103 and the projection lens 109.
In the present embodiment, the light source 10 is provided.
1 and the polarizing beam splitter 103.
8 is provided. In this case, the polarizing device 1
08 polarizing film transmits P-polarized light of incident light,
It is arranged so that S-polarized light is absorbed by the polarizing film. As described above, when a polarizing film is provided in a so-called illumination system, it is greatly affected by heat generated due to absorption of light from a light source. For this reason, in the polarizing film of the prior art, the polarization separation characteristics deteriorate due to thermal deformation. However, in the present embodiment, as described above, the polarizing device 108 includes the polarizing film member 1082 and the transparent glass plate members 1081a and 1081b that are substantially parallel flat plates, and the adhesive layers 1083a and 1083b from both sides. It is formed by adhesion and fixation. For this reason, it is possible to satisfactorily separate the light from the light source without causing thermal deformation.

In each of the above embodiments, the P-polarized light is made incident on the color separation / combination prism. Then, S-polarized light is formed as modulated light, and the light is analyzed by a polarization beam splitter. However, the present invention is not limited to this, and can also be applied to a projection display device of a type in which S-polarized light is made incident on a color separation / combination prism and then P-polarized light is used as modulated light. In this case, the polarizing device 108 is disposed between the polarizing beam splitter and the projection lens so as to transmit the P-polarized light. With this configuration, it is possible to provide a projection display device that can obtain a projection image with good contrast.

Further, another configuration of the projection type display device will be described. First, light emitted from a plurality of light valves is made incident on a polarizing beam splitter arranged for each color light. Then, the detected color lights are combined by a color combining optical system. Finally, the combined light is projected on a screen by a projection lens. In the projection display device having this configuration,
By arranging the polarizing device 108 in the optical path between the polarizing beam splitter and the projection lens, it is possible to provide a projection display device capable of obtaining a projected image with good contrast as in the above embodiments. it can.

[0046]

As described above, according to the present invention,
At least one of the polarization separation optical system and the analysis optical system has a polarizing film member sandwiched between substantially parallel flat glass plates. As a result, since accurate polarization separation can be performed with little thermal deformation, the projection type can always obtain a projection image which is inexpensive, has a simple configuration, and always has good contrast, without being affected by heat generation, changes in environmental temperature, and the like. A display device can be provided.

Further, according to a preferred embodiment, a polarizing film member sandwiched between substantially parallel plate glasses is provided on the light source side of the polarizing beam splitter. Thus, desired polarized light can be sent to the light valve.

[Brief description of the drawings]

FIG. 1 is a diagram showing a configuration of a projection display device according to a first embodiment.

FIG. 2 is a diagram illustrating a configuration of a polarization conversion device.

FIG. 3 is a sectional configuration diagram of a polarizing device.

FIG. 4 is a diagram showing a configuration of a projection type display device according to a second embodiment.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 101 Light source 102 Polarization conversion device 103 Polarization beam splitter 104, 105, 106 Prism 107R, 107G, 107B Reflection type light valve 108 Polarization device 1081a, 1081b Substantially parallel flat glass 1082 Polarization film 109 Projection lens SC screen

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 2H049 BA02 BA05 BA06 BB03 BC22 2H088 EA14 HA01 HA13 HA20 HA21 HA24 HA28 MA02 MA20 2H091 FA05X FA10X FA14X FA26X FA37X FA41X FB02 FC01 FC02 GA01 GA17 LA12 LA17 5C060 AA01 BA01 BA03 BA05 GB01 GB06 HC14 HC22 HC24 JA17

Claims (4)

[Claims] 1. A polarization separation optical system for polarizing and separating light from a light source, and a reflection type light valve disposed at a position where light polarized and separated by the polarization separation optical system is incident, and modulating and emitting incident light. And a projection display apparatus having an analysis optical system for analyzing light emitted from the reflection type light valve, wherein at least one of the polarization separation optical system and the analysis optical system is one of incident light. A projection display device, comprising: a polarizing film member having a characteristic of emitting specific linear polarized light and absorbing other than the specific linear polarized light, wherein the polarizing film member is sandwiched between heat-resistant optical members. 2. The polarization separation optical system and the analysis optical system include a common polarization beam splitter that also functions as the polarization separation optical system and the analysis optical system. The polarizing film member sandwiched between the heat-resistant optical members is provided on the light-emitting side, and the incident surface and the emission surface of the analysis light of the heat-resistant optical member sandwich the polarizing film member. The projection type display device according to claim 1, wherein the surface is a surface polished later. 3. The polarization separation optical system and the analysis optical system are shared by a common polarization beam splitter that also functions as the polarization separation optical system and the analysis optical system. The projection display device according to claim 1, wherein the polarizing film member sandwiched between the heat-resistant optical members is provided on a light source side. 4. The projection display device according to claim 1, wherein the light incident surface of the heat resistant optical member has an anti-reflection film.