JPH1054969A - Projection type display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a much brighter projected image while realizing the high luminance and the high resolution of the projected image by using a few liquid crystal light valves. SOLUTION: A light beam from a light source 1 is separated to 1st and 2nd polarized light beams by a polarizing beam splitter 2. The 1st polarized light beam is color-separated by a cross dichroic prism 7. The respective color light beams color-separated are modulated by the reflection type light valves 8R, 8G and 8B and color-synthesized by the prism 7. The color-synthesized light beams are analyzed by a polarizing beam splitter 6. The 2nd polarized light beam is modulated according to a luminance signal by the reflection type light valve 8Y and analyzed by the beam splitter 2. The respective analyzed light beams analyzed by the beam splitters 6 and 2 are polarized and synthesized by a polarizing beam splitter 9. The polarized and synthesized light beams are projected by a projection lens 54.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a projection type display device for projecting an image formed on a liquid crystal light valve onto a screen, and more particularly, to a method for displaying images formed on a plurality of color component liquid crystal light valves on a plurality of screens. The present invention relates to a projection display device that illuminates with illumination light of a color component, combines these images, and projects the combined image with a projection optical system.

[0002]

2. Description of the Related Art It has already been known that white light from a light source is split into P-polarized light and S-polarized light by a polarizing beam splitter (PBS), and both polarized lights are incident on a liquid crystal panel to improve the brightness of the projected light. Are known. For example, JP-A-4-185
FIG. 1 of Japanese Patent Application Publication No. 54-54204 discloses a configuration of a liquid crystal projector as a basic principle, and FIG. 2 of the same application discloses a configuration of a full-color projector using the same principle. The configuration of this full-color projector will be briefly described. In this projector, the light source light emitted from the light source is PB
The light is separated into P-polarized light transmitted by S (which is S-polarized light in the publication, but an error of P-polarized light) and S-polarized light reflected by the PBS. Both the separated P-polarized light and S-polarized light are separated into red light (R light), green light (G light) and blue light (B light) by a dichroic mirror. Each of the color-separated color lights is modulated by a transmission-type liquid crystal panel, and the incident-side polarizing plate transmits P-polarized light when the polarizing plate on the output side of the panel is arranged orthogonal to the polarizing plate on the incident side. When the incident side polarizer is configured to transmit S-polarized light, the light is converted into P-polarized light and emitted. Each polarized light emitted from the liquid crystal panel is combined for each polarized light by a combining dichroic mirror, further combined by a combining polarizing beam splitter, and projected by a projection lens.

However, in this method, the projected image is certainly brighter than the method of discarding one of the polarized lights separated by the separating polarizing beam splitter. In addition to the necessity of the same number of dichroic mirrors as that of one polarized light, in order to improve the resolution, six expensive high-resolution liquid crystal panels must be prepared.

As another conventional example, a projection type display device using three light valves for color signals and one light valve for luminance signals is disclosed in Japanese Patent Laid-Open Publication No. Hei 3-296030. The embodiment shown in FIG. 1 of the same publication is shown in FIG. 6 as a conventional example. According to the publication, the light source light from the light source 201 is polarized and separated by the polarization beam splitter 202,
One of the transmitted P-polarized lights is converted to a dichroic mirror 2
The color separation optical system composed of the color separation optical systems 10 and 215 separates the color-separated R, G, and B lights into light valves 20 for respective color signals.
6,207,208, and each light valve 20
The light is modulated by the color signals 6, 207 and 208 and emitted from the light valves 206, 207 and 208. On the other hand, the other S-polarized light is supplied to the light valve 20 for luminance signal.
4 and is modulated by a luminance signal and emitted from the luminance signal light valve 204 as modulated light. The dichroic mirrors 213 and 21 for color synthesis use the color signal modulated light.
4 is a device that performs color synthesis at 4, and combines the color-combined light and the luminance signal modulated light with the combining polarizing beam splitter 209, and then projects the combined light with the projection lens 219. In addition,
In FIG. 6, 203, 211, and 218 are mirrors, 205 is a terminal for supplying a luminance signal Y, and 212, 216, and 217 are terminals for supplying color difference signals R-Y, G-Y, and B-Y as color signals, respectively. It is. According to this device, the number of light valves to be used can be reduced to four, and high luminance can be achieved because the modulated light by the luminance signal is superimposed on the modulated light by the chrominance signal. By setting the resolution, a high-resolution projected image can be obtained.

[0005]

However, recently, the projection type display device has been required to have a large screen and a higher brightness of a projected image, and the conventional projection type display device has been required. With the display device, a projection image with sufficient brightness could not be obtained.

SUMMARY OF THE INVENTION The present invention has been made in view of such circumstances, and it is possible to reduce the cost by using a small number of liquid crystal light valves and obtain a high-luminance and high-resolution projection image. It is an object of the present invention to provide a projection display device capable of obtaining a brighter projected image.

[0007]

Means for Solving the Problems The present inventors have considered how to increase the brightness of a projected image in the conventional projection display device. First, the present inventors considered using a high-output light source. However, doing so increases the required power, increases the cost of the light source itself including the lamp, and generates heat generated with the increase in output. There are also many issues such as the problem of.

Therefore, the present inventors have focused on a light valve as a basic member for generating a projected image in the conventional projection display device. Considering the structure of the transmission type light valve used in the conventional projection display device, the aperture ratio of the light valve is determined by the thin film transistor (T) that switches the pixels of the light valve.
FT), and the decrease in the aperture ratio impairs the brightness of the projected image. For this reason, the present inventors considered improving the aperture ratio of the transmission light valve, but there is a limit to the improvement of the aperture ratio in the transmission light valve in which the aperture ratio is reduced by the thin film transistor.

In view of the above, the present inventors have proposed a light valve in which a TFT for switching a pixel is made invisible, that is, a reflection type in which the TFT is disposed below the pixel and the pixels are closely arranged above the pixel. I came to remember using a light valve. The use of a reflection type light valve can reduce a decrease in the amount of light as compared with the case where a transmission type light valve is used, so that a brighter projected image can be obtained.

The present invention has been made based on such ideas of the present inventors.

That is, in order to solve the above-mentioned problem, the projection type display device according to the first aspect of the present invention comprises first and second projection devices.
, A color separation optical system, first, second, and third color signal light valves each including a reflective light valve, a color combining optical system, and a luminance signal including a reflective light valve. , A polarization combining optical system, and a projection optical system. The first polarization beam splitter polarizes and separates light from a light source into a first polarization light and a second polarization light. The color separation optical system,
The first polarized light is color-separated into first, second and third colored lights. The first, second, and third color signal light valves modulate the first, second, and third color lights based on predetermined color signals, respectively. The color synthesizing optical system synthesizes each color light modulated by the first, second, and third color signal light valves. The second polarizing beam splitter detects light that has been color-combined by the color-combining optical system. The luminance signal light valve modulates the second polarized light based on a predetermined luminance signal. The first
The polarization beam splitter detects the light modulated by the luminance signal light valve. The polarization combining optical system combines the light detected by the second polarization beam splitter with the light detected by the first polarization beam splitter. The projection optical system projects the light polarized and combined by the polarization combining optical system.

According to the first aspect, similarly to the conventional projection display device, the first polarization beam splitter acting as a polarization separation optical system, the color separation optical system, a plurality of color signal light valves, Equipped with a color synthesizing optical system, a light valve for luminance signal, a polarization synthesizing optical system, and a projection optical system, so that a small number of liquid crystal light valves can be used to reduce costs and obtain a high-luminance and high-resolution projection image be able to. And in this first aspect, the first and second
And a light valve for the third color signal and a light valve for the luminance signal, wherein a reflection type light valve capable of emitting a modulated light having a large aperture ratio and brighter than a transmission type light valve is used. A brighter projected image can be obtained as compared with a conventional projection display device.

As a specific embodiment of the first embodiment,
Projection display devices according to the following second to ninth aspects can be given.

According to a second aspect of the present invention, in the projection type display device according to the first aspect, the first polarized light is transmitted through the second polarization beam splitter. It is incident on the optical system.

The projection display apparatus according to a third aspect of the present invention is the projection display apparatus according to the first or second aspect, wherein the color separation optical system and the color synthesis optical system are the same optical system. It is shared.

In a projection type display according to a fourth aspect of the present invention, in the projection type display according to the third aspect, the same optical system comprises a cross dichroic prism.

In a projection type display according to a fifth aspect of the present invention, in the projection type display according to the third aspect, the same optical system is formed by bonding three prism members with a dichroic film interposed therebetween. It is composed of a combined dichroic prism by being combined or facing each other with a gap.

A projection display apparatus according to a sixth aspect of the present invention is the projection display apparatus according to any one of the first to fifth aspects, wherein the second polarization beam splitter and the polarization combining optical system are connected to each other. A polarizing means for increasing the degree of polarization of the light detected by the second polarizing beam splitter is disposed therebetween.

According to the sixth aspect, the light detected by the second polarizing beam splitter by the polarizing means,
That is, the degree of polarization of the detected light obtained by performing color synthesis of the modulated light based on the color signal is improved. For this reason, the contrast of the projected image is improved.

The projection display apparatus according to a seventh aspect of the present invention is the projection display apparatus according to any one of the first to sixth aspects, wherein the light source and the first polarization beam splitter are disposed between the light source and the first polarization beam splitter. A shaping optical system is provided, and is an illumination relay optical system that guides the first polarized light to the second polarizing beam splitter between the first polarizing beam splitter and the second polarizing beam splitter. And an illumination relay optical system having first and second illumination lenses.

When the illumination relay optical system is employed as in the seventh aspect, the second polarized light (light for a color signal) polarized and separated by the first polarized beam splitter is converted into the second polarized light. The beam splitter, the color separation optical system, the color combining optical system, the light valve for each color signal, the first polarization beam splitter and the polarization combining optical system are positioned such that the principal ray determined by the aperture stop of the projection optical system has telecentricity. Can be arranged. Further, with respect to the second polarized light (light for a luminance signal) polarized and separated by the first polarized beam splitter, the first polarized beam splitter and the polarization combining optical system are determined by the aperture stop of the projection optical system. The principal ray can be arranged at a position having telecentricity. Therefore, according to the seventh aspect, the contrast unevenness of the projected image caused by the incident angle characteristic of the principal ray of the color signal light valve, and the contrast of the projected image caused by the incident angle characteristic of the principal ray of each polarization beam splitter. It is possible to eliminate unevenness and color shading due to the incident angle characteristic of the principal ray of the color combining optical system.

According to an eighth aspect of the present invention, in the projection type display device according to any one of the first to seventh aspects, the optical path length correction member comprises the first polarization beam splitter and the first polarization beam splitter. It is arranged so as to be located in the middle of the optical path between the second polarizing beam splitter and in the middle of the optical path between the first polarizing beam splitter and the light valve for luminance signal. is there.

When the optical path length correcting member is used as in the eighth aspect, a compact arrangement of the components can be realized.

In a projection type display according to a ninth aspect of the present invention, in the projection type display according to the seventh aspect, the optical path length correcting member comprises the first polarization beam splitter and the second polarization beam splitter. And the optical path length correction member is disposed so as to be located in the middle of the optical path between the first polarization beam splitter and the light valve for the luminance signal. First
And the second illumination lens.

[0025]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a projection type display device according to the present invention will be described in detail with reference to the drawings.

(First Embodiment) First, the first embodiment of the present invention will be described.
The projection type display device according to the embodiment will be described with reference to FIGS. 1 and 2. FIG.

FIG. 1 is a perspective view showing a schematic configuration of a projection display device according to the present embodiment. For simplicity of explanation, coordinate axes X, X shown in FIG.
Y and Z are defined (the same applies to FIGS. 3 and 4 showing a second embodiment described later). FIG. 2 is a cross-sectional view along the XZ plane in FIG. The coordinate axes in FIG.
It corresponds to the one.

In the projection type display device according to the present embodiment,
The light source 1 includes a lamp 1a and a concave mirror 1b disposed on the back of the lamp 1a. The light source light emitted from the light source 1 passes through an infrared light absorption filter and an ultraviolet light absorption filter (not shown), further passes through a concave lens 51 as a shaping optical system having negative power, and passes through a first polarizing beam splitter 2. Incident in the X direction. The light that has entered the first polarization beam splitter 2 is reflected by the polarization splitting section of the first polarization beam splitter 2 and emitted from the first polarization beam splitter 2 in the Z direction. In the embodiment, the polarization beam splits into an S-polarized light beam and a second polarized light beam (in this embodiment, a P-polarized light beam) transmitted through the polarization splitter and emitted from the first polarization beam splitter 2 in the X direction. It is polarized and separated.

The first polarized light (S-polarized light) reflected by the first polarizing beam splitter 2 and traveling in the Z direction is reflected by the bending mirror 3 and travels in the X direction. The light is reflected by and travels in the −Z direction, passes through the optical path length correction member 5 via the first illumination lens 52 forming the illumination relay optical system, and forms the second illumination relay optical system. Is incident on the second polarization beam splitter 6 via the illumination lens 53 of the first embodiment. The second polarization beam splitter 6 converts the first polarized light (S-polarized light) incident on the second polarization beam splitter 6 in the -Z direction in this manner into the second polarization beam splitter 6. It is arranged so as to reflect in the X direction at the polarization splitting section. Therefore, the first polarized light (S) incident on the second polarization beam splitter 6 via the illumination lens 53
The polarized light) is reflected in the X direction at the polarization splitting section of the second polarization beam splitter 6, travels in the X direction, and is incident on the cross dichroic prism 7, which is shared as a color separation optical system and a color synthesis optical system. You.

The cross dichroic prism 7 includes four right-angled isosceles triangular prisms such that the R light reflecting dichroic film 7R and the B light reflecting dichroic film 7B formed on each side face are orthogonal to each other to form an X-shape. It has a structure in which right-angled portions are joined together and bonded together with an adhesive. The S-polarized light incident on the cross dichroic prism 7 in the X direction is reflected by the R light reflecting dichroic film 7R and travels in the Y direction, and the R light is reflected by the B light reflecting dichroic film 7B and reflected in the −Y direction. Are separated into G light traveling through the dichroic films 7R and 7B and G light traveling in the X direction. The R light, G light, and B light emitted from the cross dichroic prism 7 are used as color signal light valves 8R, provided corresponding to the respective color lights.
8B and 8G respectively. In the present embodiment,
As the color signal light valves 8R, 8B, 8G, electric writing type reflection light valves are used.

Here, the electric write type reflection type light valve will be described with reference to FIG. FIG. 5 is a schematic cross-sectional view showing an example of an electric writing type reflective light valve. As shown in FIG. 5, an electric writing type reflective light valve comprises a transparent glass substrate 101, a transparent ITO electrode 10
2. Liquid crystal alignment film 103, TN liquid crystal layer 104, liquid crystal alignment film 105, reflective electrode 106, conductors 107 and 108 connecting between reflective electrode 106 and TFT drain 112, TF
T drain 112, TFT gate 110, TFT source 111, TFT oxide layer 109, and silicon substrate 11
3 is provided. In FIG. 5, reference numeral 114 denotes a TFT source diffusion region, and reference numeral 115 denotes a TFT drain diffusion region. When a voltage is applied to the gate 110, the TFT switches and a voltage is applied between the electrode 106 and the counter electrode 102 via the drain 112, and the liquid crystal molecules at that location are arranged in parallel with each other. The liquid crystal layer 104 at that location functions as a 波長 wavelength plate. For this reason, the polarized light that has entered the relevant portion becomes circularly polarized light and is incident on the metal reflective electrode 106, is reflected by the electrode 106 in the opposite direction, and when passing through the liquid crystal 104 again, the incident light is The light is emitted as polarized light whose polarization direction is shifted by 90 degrees. On the other hand, at a place where no voltage is applied to the gate 110, the TFT is not switched, so that no electric field is generated between the electrode 106 and the counter electrode 102.
The liquid crystal molecules are aligned according to the alignment films 103 and 105, and the incident light is rotated and incident according to the liquid crystal molecules.
The light is reflected by the metal electrode 106, turned again according to the twist of the liquid crystal molecules, and is emitted as polarized light having the same polarization direction as the incident light. Polarized light whose polarization direction deviates by 90 degrees from the polarization direction of the incident light can be emitted only at the locations selected in this way. The above is the function of the electric writing type reflection type light valve. The electric writing type reflection type light valve basically converts the polarization direction of the reflected outgoing light at an electrically selected location to a polarization direction different from the incident light. It has a function to make In the case of an electric writing type reflective light valve having such a structure, the TFT can be arranged below the electrode 106, so that the area of the electrode 106 can be increased and the aperture ratio can be significantly increased. Can be.

Referring again to FIGS. 1 and 2, S-polarized R light, G light and B light which have been separated by the cross dichroic prism 7 and incident on the color signal light valves 8R, 8B and 8G respectively are shown in FIG. The light valves 8R,
The light is emitted from 8B and 8G and is incident on the cross dichroic prism 7 again. As can be seen from the principle of the above-described electric writing type reflection type light valve, the modulated light of each color includes P-polarized light where voltage is applied according to each color signal and S-polarized light where no voltage is applied. Light is mixed. The modulated light of R light emitted from the light valve 8R is reflected in the -X direction by the R light reflecting dichroic film 7R, and the modulated light of G light emitted from the light valve 8G passes through the G light reflecting dichroic films 7R and 7G. The modulated light of the B light transmitted through the light valve 8B and transmitted from the light valve 8B as it is passes through the B light reflecting dichroic film 7B.
Reflected in the direction. In this way, the modulated light of each color is synthesized by the cross dichroic prism 7 and emitted in the −X direction. The color-combined modulated light is shown in FIG.
As shown in FIG. 2 and FIG. 2, the light enters the second polarization beam splitter 6 again and is analyzed by the second polarization beam splitter 6. That is, only the P-polarized light of the modulated light that has undergone color synthesis passes through the second polarization beam splitter 6 and is −
The S-polarized light, which travels in the X direction (that is, is analyzed) and is color-synthesized, is converted into the second polarized beam splitter 6.
And is discarded in the Z direction. Second
The detection light (P-polarized light) detected by the polarization beam splitter 6 and traveling in the −X direction is incident on a third polarization beam splitter 9 as a polarization combining optical system, and the third polarization beam The light passes through the splitter 9 and travels in the −X direction toward the projection lens 54 as a projection optical system.

On the other hand, the first polarizing beam splitter 2
Of the light source light incident on the second polarizing beam splitter 2 of the first polarizing beam splitter 2 and traveling in the X direction.
(P-polarized light) is incident on the luminance signal light valve 8Y in the X direction via the optical path length correcting member 5. As the light valve 8Y for the luminance signal, an electric writing type reflection light valve is used. The luminance signal light valve 8Y includes the color signal light valves 8R and 8R.
B and 8G, but the number of pixels is larger than that of the color signal light valves 8R, 8B and 8G. By doing so, the light modulated by the high-definition luminance signal can be emitted from the light valve 8Y.

The second polarized light (P-polarized light) incident on the luminance signal light valve 8Y is modulated by the luminance signal and reflected, and is emitted as modulated light from the luminance signal light valve 8Y in the -X direction. Is done. As can be understood from the principle of the above-described electric writing type reflection type light valve, this modulated light has a S at a portion where a voltage is applied according to a luminance signal.
The polarized light is mixed with the P-polarized light where no voltage is applied. The modulated light emitted from the luminance signal light valve 8Y in the -X direction is again incident on the first polarization beam splitter 2 via the optical path length correction member 5, and is analyzed by the first polarization beam splitter 2. Is done. That is, only the S-polarized light of the modulated light is reflected by the polarization separation unit of the first polarization beam splitter 2 and travels in the −Z direction (that is, is analyzed), and the P-polarized light of the modulated light is The polarized light passes through the first polarizing beam splitter 2 and is discarded in the -X direction. The detected light (S-polarized light) detected by the first polarizing beam splitter 2 and traveling in the −Z direction is emitted from the first polarizing beam splitter 2 and is disposed at a position immediately after the first polarizing beam splitter 2. And enters the third polarization beam splitter 9 in the −Z direction. The polarizing plate 10 is arranged to transmit only S-polarized light. Therefore,
When the analysis light (S-polarized light) based on the luminance signal passes through the polarizing plate 10, the ratio between the S-polarization component (so-called signal component) and the P-polarization component (so-called noise component) in the analysis light further increases. And, as a result, the contrast of the projected image is improved. That is, in the present embodiment, the polarizing plate 10
Constitutes a polarization means for increasing the degree of polarization of the light detected by the second second polarization beam splitter 6. However, in the present invention, it is not always necessary to use such a polarizing means. The analysis light (S-polarized light) based on the luminance signal incident on the third polarization beam splitter 9 in the −Z direction is
The light is reflected by the polarization splitting portion of the third polarization beam splitter 9 and travels in the −X direction toward the projection lens 54.

The color-combined analysis light (P-polarized light) detected by the second polarization beam splitter 6 and the luminance signal analysis light (S-polarized light) detected by the first polarization beam splitter 2 As described above, both light beams are emitted from the third polarization beam splitter 9 and travel in the −X direction, so that they are polarized and synthesized by the third polarization beam splitter 9. The polarized light is projected on a screen (not shown) by the projection lens 54.

Next, the state of light rays in the projection type display device according to the present embodiment will be described with reference to FIG.

The third polarization beam splitter 9 is set to -X
As shown in FIG. 2, the projection lens 54 for projecting the combined light emitted in the directions on the screen includes an aperture stop 54a, and a front lens group located closer to the third polarization beam splitter 9 than the aperture stop 54a. And a rear lens group located on the screen side (not shown) with respect to the aperture stop 54a.
The aperture stop 54a is disposed at a focal point on the rear side (the screen side is the rear side) of the front lens group, and the projection lens 54 is a telecentric optical system on the third polarization beam splitter 9 side (front side). ing. That is, a light beam passing through the center of the aperture stop 54a, that is, the projection lens 5
The principal ray determined by the fourth aperture stop 54a is parallel to the optical axis on the front side of the projection lens 54.

As described above, the light source 1 is composed of the lamp 1a and the concave mirror 1b arranged on the back of the lamp 1a. In the present embodiment, an elliptical mirror is used as the concave mirror 1b, and the lamp 1a is arranged at a closer focal point (first focal point) of the elliptical mirror. Therefore, the light source light emitted from the light source 1 apparently travels so as to be converged toward a far (second) focus position of the elliptical mirror 1b. The concave lens 51 as the shaping optical system includes:
It is arranged on the side of the light source 1a with respect to the position of the second focal point. The concave lens 51 condenses the second polarized light of the light source light transmitted through the first polarized beam splitter 2 onto the luminance signal light valve 8Y, taking the optical path length correction member 5 into consideration. It is configured to be. The second
Is condensed by the concave lens 51 with a width such that the light condensing point on the luminance signal light valve 8Y has substantially uniform brightness, and illuminates the luminance signal light valve 8Y. Become.

The first polarized light of the light source reflected by the first polarizing beam splitter 2 is the same as the luminance signal light valve 8Y irradiated by the second polarized light by the concave lens 51. The light is condensed at the position of the optical path length (the position between the bending mirror 3 and the bending mirror 4). Then, the first polarized light emitted from the focal point is the first illumination lens 52 disposed at a position of an optical path length f1 (f1 is a focal length of the first illumination lens 52) from the focal point. And the optical path length f1 + f2 from the first illumination lens 52 with the optical path length correction member 5 interposed therebetween.
(F2 is the focal length of the second illumination lens 53), the light is incident on the second polarization beam splitter 6 via the second illumination lens 53, and the second polarization beam splitter 6 The light is reflected by the polarization splitting unit, is incident on the cross dichroic prism 7, and is separated by the cross dichroic prism 7 into R light, G light, and B light. Second
From the illumination lens 53 of each color light valve 8R, 8
The optical path lengths up to G and 8B are the second illumination lens 5 respectively.
The focal length is set to f3. The color lights separated by the cross dichroic prism 7 are respectively provided with light valves 8R, 8G, 8B for the respective color lights arranged near the respective emission surfaces of the respective color lights of the cross dichroic prism 7.
, And is reflected by each of the light valves 8R, 8G, 8B after being modulated by the respective color signals, and is again incident on the cross dichroic prism 7 from the respective exit surfaces of the cross dichroic prism 7. The modulated lights of the respective colors incident on the cross dichroic prism 7 are color-combined by the cross dichroic prism 7 and analyzed by the second polarization beam splitter 6.

With the above configuration, the first polarized light of the source light, which is present in the optical path between the bending mirror 3 and the bending mirror 4 and is reflected by the first polarization beam splitter 2, is collected. The image of the unit is formed on the light valves 8R, 8G, 8B for the respective color lights by the illumination relay optical system composed of the first and second illumination lenses 52, 53, and the light for the respective color lights. Valve 8R, 8
Critical illumination is achieved for G, 8B. Further, the principal ray determined by the aperture stop 54a of the projection lens 54 is a light source 1 → a concave lens 51 → a first polarizing beam splitter 2 → a bending mirror 3 → a bending mirror 4 → a first illumination lens 52 → an optical path length correcting member. 5 → second illumination lens 5
3 → second polarizing beam splitter 6 → cross dichroic prism 7 → light valves 8R, 8G, 8 for each color light
B → the cross dichroic prism 7 → the second polarization beam splitter 6 → the third polarization beam splitter 9 → in the color signal optical system constituted by the path of the projection lens 54, between the concave lens 51 and the first illumination lens 52 In the optical path of, and the optical path between the second illumination lens 53 and the projection lens 54, the principal ray is parallel to the optical axis, and the telecentricity is maintained. In other words, the second polarization beam splitter 6, the cross dichroic prism 7, the light valves 8R, 8G, and 8 relate to the first polarization light polarized and separated by the first polarization beam splitter 2.
B, the first polarization beam splitter 2 and the third polarization beam splitter 9 are all located at positions where the principal ray determined by the aperture stop 54a of the projection lens 54 has telecentricity.

In the luminance signal optical system, of the light source light, the second polarized light transmitted through the polarization splitting portion of the first polarization beam splitter 2 is transmitted to the luminance signal light valve 8Y by the concave lens 51. Therefore, the same illumination as the critical illumination is achieved for the luminance signal light valve 8Y. The polarized light thus incident on the light valve 8Y is modulated by the luminance signal, reflected by the light valve 8Y, passes through the optical path length correction member 5, and is transmitted to the first polarization beam splitter 2. The light is incident and is analyzed by the first polarization beam splitter 2. Light source 1 → concave lens 51 → first polarization beam splitter 2 → optical path length correction member 5 → light valve 8Y for luminance signal → optical path length correction member 5 → first polarization beam splitter 2 → polarizing plate 10 → third polarization beam Splitter 9
→ In the luminance signal optical system constituted by the path of the projection lens 54, the optical path between the concave lens 51 and the first illumination lens 52 and the optical path between the luminance signal light valve 8Y and the projection lens 54 are mainly The light rays become parallel to the optical axis, and the telecentricity is maintained. In other words, regarding the second polarized light polarized and separated by the first polarized beam splitter 2, both the first polarized beam splitter 2 and the third polarized beam splitter 9
The principal ray determined by the aperture stop 54a of the projection lens 54 is arranged at a position having telecentricity.

If the incident angles of the off-axis chief rays are different from each other, the polarization splitting portions of the polarization beam splitters 2, 6, and 9 have different polarization splitting characteristics. In this regard, in the present embodiment, the polarization beam splitters 2, 6, and 9 are related to the first polarized light polarized and separated by the first polarization beam splitter 2 (that is, for the color signal optical system). Since the principal ray is located at a position having telecentricity, contrast unevenness of the projected image does not occur due to the incident angle characteristic of the principal ray of the polarization beam splitters 2, 6, and 9.

The dichroic films 7R and 7B for performing color separation and color synthesis are formed by laminating a plurality of dielectric films, and these films 7R and 7B have reflection characteristics according to the incident angle of the incident light beam. Has different characteristics. For this reason, if the angles of incidence on the films 7R and 7B differ for each off-axis principal ray, color shading occurs on the screen. In this regard, according to the present embodiment, the cross dichroic prism 7 serving as the color separation optical system and the color synthesis optical system is arranged at a position where the main light beam has telecentricity. Does not cause color shading due to the incident angle characteristics.

Further, the liquid crystal light valves 8R, 8G, 8
If the incident angle of the off-axis chief ray also differs for B, the modulation characteristics of the liquid crystal layer differ, and as a result, contrast unevenness occurs in the projected image. In this regard, in this embodiment, since the light valves 8R, 8G, and 8B are arranged at positions where the principal ray has telecentricity, the light valve 8R
No contrast unevenness of the projected image occurs due to the incident angle characteristics of the principal rays of R, 8G, and 8B.

For the second polarized light polarized and separated by the first polarizing beam splitter 2 (that is, for the luminance signal optical system), a luminance signal light valve 8 is provided.
In the optical path from Y to the projection lens 54 via the polarizing beam splitters 2 and 9, the principal ray is parallel to the optical axis,
Since the polarization beam splitters 2 and 9 are arranged at positions where the principal rays have telecentricity, there is no occurrence of contrast unevenness of the projected image due to the incident angle characteristics of the principal rays of the polarization beam splitters 2 and 9. In the luminance signal optical system, in the optical path from the concave lens 51 to the luminance signal light valve 8Y via the first polarizing beam splitter 2, the principal ray is not parallel to the optical axis (that is, the luminance signal light). The bulb 8Y is not disposed at a position where the principal ray has telecentricity), and the incident angle of the off-axis principal ray incident on the luminance signal light valve 8Y is different. As a result, the unevenness of the projected image is caused. obtain. However, in the present embodiment, the modulated light emitted from the luminance signal light valve 8Y is analyzed by the first polarizing beam splitter 2, and the analyzed light is transmitted through the polarizing plate 10. The occurrence of contrast unevenness is prevented.

Since the projection image on the screen and the light valves 8Y, 8R, 8G, 8B are conjugate with respect to the projection lens 54, the light valves 8R, 8G, 8B
And the optical path length from the light valve 8Y to the projection lens 54 via the polarization beam splitters 6 and 9 is the same as the optical path length from the light valve 8Y to the projection lens 54 via the optical path length correction member 5 and the polarization beam splitters 6 and 9. There is a need to. For this reason, in the present embodiment, the length of the optical path length correction member 5 in the X direction is determined in consideration of the refractive index of the optical path length correction member 5.
Both optical path lengths are determined so as to be the same. The length of the optical path length correction member 5 in the Z direction is adjusted by adjusting the optical path length between the first and second illumination lenses 52 and 53 to constitute the illumination relay optical system of the color signal optical system. The light bulbs 8R, 8G,
It is defined that critical illumination for 8B is achieved. As can be seen from the above description, the optical path length correction member 5 is located in the middle of the optical path (optical path of light for color signals) between the first polarizing beam splitter 2 and the second polarizing beam splitter 6. In addition, it is arranged so as to be located in the middle of an optical path (optical path of light for luminance signal) between the first polarization beam splitter and the light valve for luminance signal. In particular, in the present embodiment, the optical path length correction member 5 includes the first illumination lens 52 and the second illumination lens 53
And is located between.

According to the present embodiment, like the above-mentioned conventional projection type display apparatus, the first functioning as a polarization separation optical system.
, A polarization beam splitter 2, a color separation optical system, a plurality of color signal light valves 8R, 8G, 8B, a color synthesis optical system, a luminance signal light valve 8Y, a polarization synthesis optical system, and a projection optical system. Since the cost is reduced by using a small number of liquid crystal light valves, and the light emitted from the luminance signal light valve 8Y is superimposed on the light emitted from the color signal light valves 8R, 8G, 8B, A high-luminance and high-resolution projected image can be obtained. In the present embodiment, all of the color signal light valves 8R, 8G, 8B and the luminance signal light valve 8Y can emit modulated light having a much larger aperture ratio and brighter than a transmissive light valve. Since the reflection type light valve is used, a brighter projected image can be obtained as compared with the conventional projection display device. Moreover, according to the present embodiment, as described above, most of the main components of the polarizing beam splitter, the dichroic film, and the light valve that depend on the angle of incidence of the chief ray have a telecentric property. Therefore, it is possible to minimize the reduction in the contrast of the projected image and the occurrence of color shading due to the incident angle characteristics of these principal rays.

In this embodiment, the light valve 8
Although the electric writing type reflective light valve is used as R, 8G, 8B, 8Y, an optical writing type reflective light valve may be used instead. However, in the case of using the optical writing type light valve, a writing optical system is required and the size of the apparatus is increased. Therefore, it is preferable to use an electric writing type light valve as in this embodiment.

(Second Embodiment) Next, a second embodiment of the present invention will be described.
The projection type display device according to the embodiment will be described with reference to FIG. 3 and FIG.

FIG. 3 is a schematic perspective view showing a projection type display device according to a second embodiment of the present invention. FIG. 4 shows FIG.
FIG. 6 is an XY plan view of a dichroic prism 27 and light valves 8R, 8G, and 8B serving as a color separation optical system and a color combining optical system in the -Z direction. In FIG. 3, the same or corresponding elements as those in FIG. 1 are denoted by the same reference numerals, and description thereof will be omitted.

The projection type display device according to the present embodiment is shown in FIG.
The only difference from the projection display device according to the first embodiment shown in FIG. 1 is that a so-called Philips type dichroic prism 27 is used instead of the cross dichroic prism 7 as an optical system for performing color separation and color synthesis. It is.

As shown in FIGS. 3 and 4, the dichroic prism 27 has three prism members 27-1, 27-2, and 27-3 having different shapes. The member 27-1 is a triangular prism, the member 27-2 is a triangular prism having a shape different from that of the member 27-1, and the member 27-3 is a quadrangular prism. An R light reflecting dichroic film 27R that reflects R light and transmits G light and B light is formed on a facing surface of the member 27-1 that faces the member 27-2 with a gap. Member 27-
An air gap is formed between 1 and the member 27-2 as described above. A B light reflecting dichroic film 27B that reflects B light and transmits G light is formed on a surface between the members 27-2 and 27-3. The member 27-2
No gap is formed between the member 27-3.

In the second embodiment, as shown in FIGS. 3 and 4, a concave lens 51, a first polarizing beam splitter 2, folding mirrors 3 and 4, a first illumination lens 52, an optical path length are provided from a light source 1. The first polarized light (S-polarized light) traveling in the X direction via the correcting member 5, the second illumination lens 53, and the second polarizing beam splitter 6 is applied to the surface of the member 27-1 of the dichroic prism 27. The light is incident on the optical axis perpendicular to 27-1-a, and is separated into R light, G light, and B light. That is, as shown in FIG. 4, the second polarization beam splitter 6
Of the polarized light incident on the member 27-1 in the X direction from
The light is reflected by the R light reflection dichroic film 27R,
Further, the internal surface is totally reflected by the surface 27-1-a of the member 27-1, and is emitted from the surface 27-1-b of the member 27-1 in a predetermined direction which is not parallel to the X axis and the Y axis. -1-
The light is incident on the R light light valve 8R arranged near b. From the second polarizing beam splitter 6 to the member 27-1
Out of the polarized light that has entered the X direction at
1, enter the member 27-2 through the R light reflecting dichroic film 27R and the gap, and are reflected by the B light reflecting dichroic film 27B, and further, the surface 27- of the member 27-2.
The surface 27-2 of the member 27-2 is totally internally reflected at 2-a.
-B is emitted in a predetermined direction that is not parallel to the X axis and the Y axis, and is incident on the light valve 8B for B light arranged near the surface 27-2-b. Among the polarized lights incident on the member 27-1 in the X direction from the second polarizing beam splitter 6, the G light is the member 27-1, the R light reflecting dichroic film 27R, the gap, the member 27-2, and the B light dichroic. The light passes through the film 27G and the member 27-3 and is emitted from the surface 27-3-a of the member 27-3 in the X direction.
Is incident on the light valve 8G for G light arranged in the vicinity of. The S-polarized R light, G light, and B light incident on the color signal light valves 8R, 8B, and 8G, respectively, are modulated and reflected by the respective color signals, and output as modulated light from the respective light valves 8R, 8B, and 8G. Then, the light is incident on the dichroic prism 27 again, travels backward in the optical path described above, is color-combined and is emitted in the -X direction from the surface 27-1-a, and the color-combined modulated light is again transmitted to the second light source. The light enters the polarization beam splitter 6. The light path lengths of the R light, the G light, and the B light are set to be the same from when the light enters the dichroic prism 27 to when the light exits the dichroic prism 27.

In this embodiment, the same advantages as those of the projection type display device according to the second embodiment can be obtained. Note that, in the present embodiment, the dichroic prism 27
R light and B light emitted from the light valves 8R and 8B are reflected twice until they are emitted from the light valves 8R and 8B.
Since the G light emitted from the G is never subjected to the reflection action, the right and left drive directions of the R, G, B light light valves 8R, 8G, 8B may all be the same.

Although the embodiments of the present invention have been described above, the present invention is not limited to these embodiments.

For example, instead of using a lamp and an elliptical mirror as the light source 1, for example, a lamp and a parabolic mirror or a spherical mirror can be used. In that case, the shaping optical system becomes a convex lens.

In each of the above embodiments,
The cross dichroic prism 7 or the Philips type dichroic prism 27 has been used as an optical system that also serves as a color separation optical system and a color synthesis optical system. Instead, three prism members are sandwiched between dichroic films. Various kinds of combined dichroic prisms may be used by bonding or facing each other with a gap therebetween.

[0058]

According to the present invention, it is possible to reduce the cost by using a small number of liquid crystal light valves, obtain a high-brightness and high-resolution projection image, and obtain a brighter projection image. it can.

[Brief description of the drawings]

FIG. 1 is a perspective view showing a schematic configuration of a projection display device according to a first embodiment of the present invention.

FIG. 2 is a schematic plan view showing a part of the projection display device according to the first embodiment of the present invention.

FIG. 3 is a perspective view showing a schematic configuration of a projection display device according to a second embodiment of the present invention.

FIG. 4 is a schematic plan view showing a part of a projection display device according to a second embodiment of the present invention.

FIG. 5 is a schematic sectional view showing an example of an electric writing type reflection type light valve.

FIG. 6 is a schematic configuration diagram showing a conventional projection display device.

[Explanation of symbols]

 Reference Signs List 1 light source 2, 6, 9 polarizing beam splitter 3, 4 bending mirror 5 optical path length correction member 7 cross dichroic prism 8R, 8G, 8B, 8Y reflective light valve 10 polarizing plate 27 dichroic prism 51 concave lens 52, 53 illumination lens 54 projection lens

Claims (9)

[Claims] 1. A first and second polarization beam splitter, a color separation optical system, first, second, and third color signal light valves each including a reflection type light valve, and a color combining optical system. A light signal valve for luminance signal comprising a reflection type light valve, a polarization combining optical system, and a projection optical system, wherein the first polarization beam splitter converts the light from the light source into the first polarized light and the second polarized light. The first polarized light is separated into first, second and third colored lights, and the first, second and third colors are separated by the color separation optical system. The signal light valve modulates the first, second, and third color lights based on predetermined color signals, respectively, and the color synthesizing optical system includes the first, second, and third color signal lights. Each of the color lights modulated by the valve is color-combined, and the second polarization beam splitter is The light synthesized by the color synthesizing optical system is analyzed, the light valve for luminance signal modulates the second polarized light based on a predetermined luminance signal, and the first polarization beam splitter includes: The light modulated by the luminance signal light valve is analyzed, and the polarization combining optical system is configured to analyze the light analyzed by the second polarization beam splitter and the light analyzed by the first polarization beam splitter. And a projection optical system, wherein the projection optical system projects the light polarized and synthesized by the polarization synthesis optical system. 2. The projection display according to claim 1, wherein the first polarized light is incident on the color separation optical system via the second polarization beam splitter. 3. The system according to claim 1, wherein the color separation optical system and the color synthesis optical system are shared by the same optical system.
Or the projection type display device according to 2. 4. The optical system according to claim 3, wherein the same optical system comprises a cross dichroic prism.
The projection type display device as described in the above. 5. The dichroic prism according to claim 1, wherein the same optical system is formed by bonding three prism members together with a dichroic film therebetween or facing each other with a gap therebetween. The projection display device according to claim 3. 6. A polarization means for increasing the degree of polarization of light detected by the second polarization beam splitter is provided between the second polarization beam splitter and the polarization combining optical system. The projection display device according to claim 1. 7. A shaping optical system is disposed between the light source and the first polarization beam splitter, and the first polarization beam splitter is disposed between the first polarization beam splitter and the second polarization beam splitter. An illumination relay optical system for guiding said polarized light to said second polarization beam splitter, wherein an illumination relay optical system having first and second illumination lenses is arranged. 7. The projection display device according to any one of 6. 8. An optical path length correction member is located in the middle of an optical path between the first polarization beam splitter and the second polarization beam splitter, and is provided for the first polarization beam splitter and the luminance signal. 8. The projection type display device according to claim 1, wherein the projection type display device is arranged so as to be located in the middle of an optical path between the light source and the light valve. 9. An optical path length correction member is located in the middle of an optical path between the first polarization beam splitter and the second polarization beam splitter, and the first polarization beam splitter and the luminance signal The optical path length correction member is disposed so as to be located in the middle of an optical path between the light source and the light valve, and the optical path length correction member is disposed between the first illumination lens and the second illumination lens. A projection display device according to claim 7.