JPH09329760A - Projection display device - Google Patents

Abstract

(57) [PROBLEMS] To obtain a projected image without color shading and contrast unevenness while achieving high brightness of the projected image. SOLUTION: Light from a light source 1 is separated into first and second polarized lights by a polarizing beam splitter 3. The first polarized light is color-separated by the cross dichroic mirror 4. The color-separated light of each color is divided into the light valves 10R and 1R.
They are respectively modulated by 0G and 10B, and are color-synthesized by the cross dichroic prism 7. The second polarized light is modulated by the brightness signal by the light valve 11, is polarized and combined with the color combined light by the polarization beam splitter 9, and is projected by the projection lens 106. The polarization beam splitters 3 and 9, the cross dichroic mirror 4 and the cross dichroic prism 7 are connected to the projection lens 106.
The principal ray defined by the aperture stop of is provided at a position where the telecentricity is maintained.

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 particularly to a plurality of images formed on liquid crystal light valves for a plurality of color components. The present invention relates to a projection type display device that illuminates with illumination light of color components, combines these images, and projects the combined image by 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 JP-A-44 discloses the structure of a liquid crystal projector as the basic principle, and FIG. 2 of the JP-A-44 discloses the structure 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. The polarized light emitted from the liquid crystal panel is synthesized for each polarized light by the synthetic dichroic mirror, further synthesized by the polarizing beam splitter for synthesis, and projected by the 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. 3 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, a device for projecting a composite image by a projection lens 219 after the color composite light is composited in 4, and the color composite light and the luminance signal modulated light are composited in a composition polarization beam splitter 209. In addition,
In FIG. 3, 203, 211 and 218 are mirrors, 205 is a terminal for supplying a luminance signal Y, 212, 216 and 217 are terminals for supplying color difference signals R-Y, G-Y and B-Y as color signals, respectively. 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, the conventional example has the following problems. That is, the spectral characteristics of the multi-layer film filters used in the dichroic mirrors and dichroic prisms used as the color separation optical system and the color combining optical system in the projection type display device of the conventional example have angle dependence. Therefore, if the angle of incidence of the principal ray on the multilayer filter determined by the aperture stop of the projection lens differs depending on the location, the spectral characteristics of the multilayer filter differ for each principal ray, and color shading occurs on the screen.

Further, since the performance of the liquid crystal light valve also depends on the angle, if the incident angle of the chief ray with respect to the light valve varies depending on the location, the uneven contrast of the projected image occurs due to this.

Furthermore, there is angle dependence in the performance of the polarization beam splitter used for polarization separation and combination.
If the incident angle of the principal ray with respect to the polarization splitting surface of the polarization beam splitter varies depending on the location, unevenness in the contrast of the projected image similarly occurs due to this.

Furthermore, when the shape and size of the image forming portion of the color signal light valve and the shape and size of the image forming portion of the brightness signal light valve are the same, the aperture ratio of both light valves (incident light) However, if the area ratio of the area where the light can be transmitted and the area where the light cannot be transmitted (the area where the switching element and the like are arranged) are the same, it is not possible to obtain a high-definition and bright projected image. That is, in the light valve, since the size of the switching element or the like provided for each pixel is limited, it is not possible to increase the number of pixels while maintaining a large aperture ratio. Therefore, when the shape and size of the image forming portion of the color signal light valve and the shape and size of the image forming portion of the brightness signal light valve are the same, increasing the number of pixels of both reduces the aperture ratio of both. As a result, the projected image becomes high-definition but dark. On the other hand, if the number of pixels of both is reduced and the aperture ratio of both is increased, the projected image becomes bright, but the resolution is lowered.

The present invention has been made in view of the above circumstances, and provides a projection type display device capable of obtaining a projected image without color shading and uneven contrast while achieving high brightness of the projected image. The purpose is to

Another object of the present invention is to provide a projection type display device capable of obtaining a high-definition and bright projection image.

[0011]

In order to solve the above-mentioned problems, a projection display according to a first aspect of the present invention comprises: a light-emitting element for separating a light from a light source into a first polarized light and a second polarized light; A polarization-separating optical system, a color-separating optical system that color-separates the first polarized light separated by the polarization-separating optical system into first, second, and third color lights; 1,
With the first, second, and third color signal light valves that modulate the second and third color lights based on predetermined color signals, respectively, and the first, second, and third color signal light valves. A color synthesizing optical system for color-synthesizing the modulated lights respectively emitted from the first, second, and third color signal light valves, and the second polarized light polarized and separated by the polarization separating optical system. A light valve for a brightness signal that modulates the light signal based on a predetermined brightness signal, light that is color-synthesized by the color combining optical system, and light that is modulated by the light valve for the brightness signal and emitted from the light valve for the brightness signal In a projection display device having a polarized light combining optical system for combining and a projection optical system for projecting the light combined by the polarized light combining optical system, the polarized light separating optical system, the color separation optical system, and the color Synthetic light System and the polarization combining optical system, the principal ray is determined by the aperture stop of the projection optical system is one which is arranged at a position having telecentricity.

According to the first aspect, in all of the polarization separating optical system, the color separating optical system, the color combining optical system and the polarization combining optical system, the chief ray determined by the aperture stop of the projection optical system is telecentric. Since it is provided in a position that maintains, the unevenness of the contrast of the projected image due to the angular characteristics of the polarization splitting optical system and the polarization combining optical system, and the angular characteristics of the color separation optical system and the color combining optical system. It is possible to eliminate all color shading of the projected image, and it is possible to obtain a projected image with excellent image quality.

A projection type display device according to a second aspect of the present invention is the projection type display device according to the first aspect, wherein the first, second and third color signal light valves and the brightness signal light are provided. A valve is arranged at a position where a chief ray determined by the aperture stop of the projection optical system has telecentricity, and the first, second and third color signal light valves and the brightness signal light valve are provided. On the other hand, telecentric lighting is performed.

According to the second aspect, since each light valve is arranged at a position where the chief ray maintains the telecentricity, and the telecentric illumination is performed on each light valve, the angle characteristic of each light valve is provided. Also, the unevenness of the contrast of the projected image due to the generation does not occur.

The projection type display device according to the third aspect of the present invention comprises a polarization splitting optical system for splitting light from a light source into first polarized light and second polarized light, and the polarization splitting optical system. A color separation optical system that color-separates the polarization-separated first polarized light into first, second, and third color lights, and the color-separated first, second, and third color lights in a predetermined manner. First, second, and third color signal light valves that are modulated based on color signals, and the first, second, and third color signal light valves that are modulated by the first, second, and third color signal light valves. A color combining optical system that performs color combination of lights emitted from the three color signal light valves, and a brightness that modulates the second polarized light polarized and separated by the polarization separating optical system based on a predetermined brightness signal. Light combined with the signal light valve and the color combining optical system A polarization combining optical system that combines the light that is modulated by the brightness signal light valve and that is emitted from the brightness signal light valve, and a projection optical system that projects the light combined by the polarization combining optical system. In the projection display device having, an integrator between the light source and the polarization splitting optical system, into which light from the light source is incident, and a first relay that guides light emitted from the integrator to the polarization splitting optical system. An optical system is provided, and the brightness signal light valve is a real image of the exit surface of the integrator formed by the first relay optical system and is the second polarized light separated by the polarization separation optical system. The color separation optical system is arranged at a position where a real image by light is formed, and is provided between the color separation optical system and the first, second, and third color signal light valves. Second and third images for forming real images of the emission surface of the integrator by the color-separated first, second and third color lights on the first, second and third color signal light valves, respectively. 3 and 4
Relay optical systems are arranged respectively.

If the configuration having the first to fourth relay optical systems is adopted as in the third aspect, the arrangements of the first and second aspects can be easily realized. Further, in the third aspect, since the integrator and the relay optical system are used, the light from the light source can be transmitted without waste.

A projection type display device according to a fourth aspect of the present invention is the projection type display device according to the third aspect, wherein the integrator is a rod integrator.

A projection type display device according to a fifth aspect of the present invention is the projection type display device according to any one of the first to fourth aspects, wherein the polarization splitting optical system and the polarization combining optical system are polarized beams. Consists of a splitter,
The color separation optical system and the color synthesis optical system each include a cross dichroic prism or a cross dichroic mirror.

A projection type display apparatus according to a sixth aspect of the present invention is the projection type display apparatus according to any one of the first to fifth aspects, wherein the luminance signal light valve and the polarization combining optical system are provided. Is an optical path length correction that causes the optical path length from the brightness signal light valve to the projection optical system to substantially match the optical path length from the first, second, and third color signal light valves to the projection optical system. The member for use is arranged.

By using the member for correcting the optical path length as in the sixth aspect, it is possible to realize a compact arrangement of each element while superimposing an image formed by a color signal and an image formed by a luminance signal with good image formation. You can

A projection type display apparatus according to a seventh aspect of the present invention is a polarization splitting optical system for splitting light from a light source into first polarized light and second polarized light, and the polarization splitting optical system. A color separation optical system that color-separates the polarization-separated first polarized light into first, second, and third color lights, and the color-separated first, second, and third color lights in a predetermined manner. First, second, and third color signal light valves that are modulated based on color signals, and the first, second, and third color signal light valves that are modulated by the first, second, and third color signal light valves. A color combining optical system that performs color combination of lights emitted from the three color signal light valves, and a brightness that modulates the second polarized light polarized and separated by the polarization separating optical system based on a predetermined brightness signal. Light combined with the signal light valve and the color combining optical system A polarization combining optical system that combines the light that is modulated by the brightness signal light valve and that is emitted from the brightness signal light valve, and a projection optical system that projects the light combined by the polarization combining optical system. In the projection display device having the above, the shape and size of the image forming portions of the first, second and third color signal light valves and the shape and size of the image forming portions of the brightness signal light valve are substantially the same. The aperture ratios of the light signal light valves are the same, and are smaller than the aperture ratios of the first, second, and third color signal light valves.

According to the seventh aspect, since the aperture ratio of the brightness signal light valve is smaller than the aperture ratio of the color signal light valve, the number of pixels of the brightness signal light valve can be sufficiently increased. With the brightness signal light valve, it is possible to obtain a high-definition brightness signal image that is relatively dark. On the other hand, since the aperture ratio of the color signal light valve is larger than that of the luminance signal light valve, the color signal light valve can provide a bright color signal image with a relatively low resolution. Therefore, since the luminance signal image and the color signal image are superimposed to form a projection image, a high-definition and bright projection image can be obtained.

According to an eighth aspect of the present invention, there is provided the projection type display device according to the seventh aspect, wherein the number of pixels of the brightness signal light valve is the first or second.
And the number of pixels of the third color signal light valve is larger. In order to obtain a high-definition projected image, it is preferable that the number of pixels of the luminance signal light valve is larger than the number of pixels of the color signal light valve as in the eighth aspect.

A projection type display device according to a ninth aspect of the present invention is the projection type display device according to the seventh or eighth aspect, wherein the light valves for the first, second and third color signals and the luminance are used. A signal light valve is arranged at a position where the chief ray determined by the aperture stop of the projection optical system has telecentricity, and the first, second and third color signal light valves and the luminance signal Telecentric lighting is performed on the light valve.

According to the ninth aspect, since each light valve is arranged at a position where the chief ray maintains the telecentricity, and the telecentric illumination is performed on each light valve, the angle characteristic of each light valve is obtained. The unevenness in the contrast of the projected image due to the phenomenon does not occur.

A projection type display device according to a tenth aspect of the present invention is the projection type display device according to any one of the seventh to ninth aspects, wherein the polarization splitting optical system, the color separation optical system, and the color combination are used. The optical system and the polarized light combining optical system are arranged at a position where the chief ray determined by the aperture stop of the projection optical system has telecentricity.

According to the tenth aspect, in all of the polarization separating optical system, the color separating optical system, the color combining optical system, and the polarization combining optical system, the chief ray determined by the aperture stop of the projection optical system is telecentric. Since it is provided in a position that maintains, the unevenness of the contrast of the projected image due to the angular characteristics of the polarization splitting optical system and the polarization combining optical system, and the angular characteristics of the color separation optical system and the color combining optical system. It is possible to eliminate all color shading of the projected image, and it is possible to obtain a projected image with excellent image quality.

[0028]

DESCRIPTION OF THE PREFERRED EMBODIMENTS A projection type display device according to an embodiment of the present invention will be described below with reference to FIGS.

FIG. 1 is a schematic perspective view showing the overall structure of a projection type display device according to an embodiment of the present invention. To facilitate understanding of the explanation, X, Y, and Z axes orthogonal to each other are defined as shown in FIG. FIG. 2 is an optical path diagram in the XZ section in FIG. 1 of the projection type display device shown in FIG. The solid line in FIG. 2 indicates the outermost marginal ray of the off-axis ray, and the broken line in FIG. 2 indicates the principal ray of the off-axis ray (the principal ray determined by the aperture stop (not shown) of the projection lens 106). There is. The coordinate system in FIG. 2 corresponds to that in FIG. In FIG. 2, the light source 1 and the projection lens 106 in FIG.
The half-wave plates 110 and 111 are not shown. In addition, in FIG. 2, since it is a cross-sectional ray diagram, the optical paths of R light and B light from color separation to color combination are omitted, and the optical path of only G light for color light is illustrated.

In the projection type display device according to this embodiment,
As shown in FIG. 1, the light source 1 is composed of an elliptic mirror and a lamp (not shown) arranged at the near focus portion of the elliptic mirror. The light emitted from the light source 1 passes through an infrared light absorption filter and an ultraviolet light absorption filter, which are not shown, and then a rod integrator 2 made of a rectangular parallelepiped transparent optical member.
The light is condensed on the end surface of the rod near the light source 1 and enters the rod integrator 2. The light incident on the integrator 2 is repeatedly reflected on the inner surface thereof a plurality of times and then is emitted from the other end face of the integrator 2 (the end face facing the incident end face), and the emission end face thereof serves as a surface light source having a uniform light intensity. Become. In the present embodiment, the cross-sectional shape and the size of the integrator 2 are the liquid crystal light valve 10 described later.
It has the same shape and size as the image forming portions of R, 10G, 10B and 11.

Next, the light emitted from the emission end surface of the rod integrator 2 travels in the X direction in the figure, passes through the equal-magnification relay lens 101 as the first relay optical system, and serves as a polarization separation optical system. Of the first polarized light (P-polarized light) which is incident on the polarization beam splitter 3 of the polarization beam splitter 3, is transmitted through the polarization splitting portion formed of the dielectric multilayer film of the polarization beam splitter 3, and is emitted in the X-axis direction, Reflected at -Z
It is polarized and separated into the second polarized light (S-polarized light) emitted in the axial direction. The first polarized light emitted from the polarization beam splitter 3 passes through the half-wave plate 110 and has a polarization direction of 90 °.
After being converted, the light is incident on the color separation optical system. In this embodiment, the color separation optical system is composed of a cross dichroic mirror 4 having a structure in which a B light reflection dichroic mirror 4B and an R light reflection dichroic mirror 4R are arranged in an X shape. The light incident on the cross dichroic mirror 4 is transmitted through the dichroic mirrors 4B and 4R, and is G light that advances in the X-axis direction without changing the optical axis.
R-light reflection dichroic mirror 4R reflects -Y
Color separation is performed into R light traveling in the axial direction and B light traveling in the Y axis direction after being reflected by the B light reflecting dichroic mirror 4B. The first polarized light (P-polarized light) emitted from the polarization beam splitter 3 in the X-axis direction is 1 as described above.
The / 2 wavelength plate 110 changes the polarization direction by 90 degrees in the same direction as the second polarized light, so that it is incident as P-polarized light on the cross dichroic film forming surfaces of the dichroic mirrors 4R and 4B. This is a cross dichroic prism 7 as a color combining optical system.
This is because the light is made to enter as S-polarized light on the dichroic film formation surface of the cross dichroic prism 7 when the colors are combined. When the incident light to the color synthesizing optical system is made into S-polarized light with respect to the color synthesizing film surface of the color synthesizing optical system in this way, the spectral characteristics of the color synthesizing film are S-polarized light as compared with the case of P-polarized light. In the case of light is better, so
Light loss can be reduced, which is preferable.

On the other hand, the second polarized light (S-polarized light) which is polarized and separated by the polarization beam splitter 3 and emitted from the polarization beam splitter 3 in the −Z-axis direction is incident on the brightness signal light valve 11. .

Although the projection lens 106 is not shown in FIG. 2, the projection lens 106 has an aperture stop (not shown), and the chief ray is determined by the aperture stop.
The chief ray passing through the center of the aperture stop is emitted by the front lens group (the light incident side is the front side and the emission (projection) side is the rear side with respect to the aperture stop) constituting the projection lens 106. The rays are parallel to the axis. That is, the projection lens 106 has a configuration in which the aperture stop is arranged at the rear focal position of the front lens group, and has telecentricity on the front side (incident side). Note that, in FIG. 2, two rays of the principal rays that pass the outermost side from the optical axis are described by dotted lines.

The light emitted from the emission surface of the integrator 2 is a unit magnification relay lens 101 (FIG. 2) having telecentricity on the emission side, for both the first and second polarized light beams polarized and separated by the polarization beam splitter 3. 1 out of 2
Reference numeral 01a is an aperture stop of the equal-magnification relay lens 101. )
Thus, a real-magnification real image (first-order real image) of the exit surface is formed at two conjugate points on the exit surface of the integrator 2 (the conjugate point for the first polarized light and the conjugate point for the second polarized light). A brightness signal light valve 11 is disposed at a position where the second polarized light forms a real-size real image of the exit surface of the integrator 2. Therefore, the brightness signal light valve 11 is arranged at a position where the principal ray has telecentricity, and is subjected to telecentric critical illumination. On the other hand, the first polarized light that passes through the polarization beam splitter 3 forms a real-magnification image I of the exit surface of the integrator 2 inside the cross dichroic mirror 4 as shown in FIG. The principal ray is parallel to the optical axis on both the incident side and the emitting side with respect to the polarization beam splitter 3, and the polarization beam splitter 3 is arranged at a position where the principal ray has telecentricity. Polarizing beam splitter 3
The polarization splitting film forming the polarization splitting part is composed of a dielectric multilayer film. The film has a property that the polarization separation ability varies depending on the incident angle of the light beam, but since the principal ray is arranged at a position having telecentricity, unevenness of the polarization separation performance due to the incident angle does not occur.

After passing through the polarization beam splitter 3, it becomes 1/2
The light that has passed through the wave plate 110 forms the same-magnification real image I, and then the cross ray dichroic mirror 4 which is also a color separation optical system with its principal ray having telecentricity.
And is separated by the mirror 4. That is, the cross dichroic mirror 4 is arranged at a position where the chief ray determined by the aperture stop of the projection lens 106 has telecentricity. The dichroic film forming the cross dichroic mirror 4 has different color separation characteristics depending on the angle of the incident light ray, but since the telecentricity with respect to the chief ray is ensured, the problem of color shading of the separated light, that is, color shading does not occur. .

The R light decomposed by the cross dichroic mirror 4 is reflected by the dichroic mirror 4R in the -Y axis direction, and the G light is transmitted through the R light reflection dichroic mirror 4R and the B light reflection dichroic mirror 4B in the X axis direction. , B light is reflected by the dichroic mirror 4B and travels in the Y-axis direction.

The R light emitted from the cross dichroic mirror 4 passes through the first illumination lens for R light composed of the lens 102R and the lens 103R, and the folding mirror 5R changes the optical axis to the -Z axis direction, and the lens 104R. And lens 1
Liquid crystal light valve 10R for R light via a second illumination lens for R light composed of 05R (a bending mirror 6R is arranged between the lenses 104R and 105R, and the optical axis is changed to the Y-axis direction). Incident on. In the present embodiment, the first illumination lens for R light and the second illumination lens for R light constitute a second relay optical system that forms a real image of the exit surface of the integrator 2 on the light valve for R light. are doing.

The G light emitted from the cross dichroic mirror 4 passes through the first illumination lens for G light composed of the lens 102G and the lens 103G, and the folding mirror 5G changes the optical axis in the -Z axis direction to form the lens 104G. Lens 105
G light liquid crystal light valve 10 via a G light second illumination lens (a bending mirror 6G is arranged between the lenses, and the optical axis is changed to the −X axis direction) composed of G and G.
It is incident on G. In the present embodiment, the first illumination lens for G light and the second illumination lens for G light are the integrator 2
Constitutes a third relay optical system for forming a real image of the exit surface of G on the light valve for G light.

The B light emitted from the cross dichroic mirror 4 passes through the first illumination lens for B light composed of the lens 102B and the lens 103B, and the folding mirror 5B changes the optical axis to the -Z axis direction, and the lens 104B. And lens 1
Liquid crystal light valve 10B for B light via a second illumination lens (a bending mirror 6B is arranged between the lenses and the optical axis is changed to the −Y axis direction) composed of
Incident on. In the present embodiment, the B-light first illumination lens and the B-light second illumination lens form a real image of the exit surface of the integrator 2 on the B-light light valve.
Of the relay optical system.

The first illumination lens for each color is composed of the same lens for each color, and is arranged at the same optical path length position from the cross dichroic mirror 4 as a color separation optical system. Further, the second illumination lens for each color is also composed of the same lens for each color, and the optical path length to the light valves 10R, 10G, 10B for each color is the same for each color.

Here, the G light of each color light is shown in FIG.
This will be described with reference to FIG. The G light that has passed through the cross dichroic mirror 4 is a third relay including a first illumination lens including a lens 102G and a lens 103G and a second illumination lens including a lens 104G and a lens 105G. It is incident on the optical system. A pupil space is formed through the first illumination lens, and the pupil is formed at the points where the chief rays intersect. Further, the chief ray emitted from the pupil is made parallel to the optical axis by the second illumination lens and is incident on the G light light valve 10G. That is, the third relay optical system constitutes a telecentric optical system in which the principal ray is parallel to the optical axis with respect to the incident side and the emitting side. Further, the G light light valve 10 is provided by the third relay optical system.
A secondary image (real image of the real image I) of the exit surface of the integrator 2 is formed on G. Therefore, a telecentric critical illumination is achieved for the G light light valve.

Regarding the R light and the B light, as in the case of the G light, the R light light valve 10R and the B light light valve 10B are provided by the second relay optical system and the fourth relay optical system. For each, telecentric critical illumination is achieved.

Here, the liquid crystal light valves 10R and 10R
B, 10G, and 11 will be described. In general, a liquid crystal light valve has a structure in which a liquid crystal panel is sandwiched between two polarizing plates forming a crossed Nicols. Although not shown in the drawing, the liquid crystal panel includes, in order from the incident light side, a transparent glass substrate, an active non-linear element (for example, a TFT) that selectively switches lattice-shaped pixels formed on the glass substrate, and a combination thereof. Electrodes that form a pixel,
It is composed of a liquid crystal layer, a counter electrode, and a transparent glass substrate. By applying a voltage between the pixel electrode and the counter electrode facing it by the active element switched by the color signal or the luminance signal for each color,
The electric field causes the liquid crystal molecules to be aligned parallel to each other and perpendicular to the substrate. Therefore, the polarized light that has passed through the incident side polarization plate passes through the panel as it is and is absorbed by the emission side polarization plate forming the crossed Nicols. On the other hand, the liquid crystal molecules maintain a twisted structure at a position not selected by the active element. In this case, the polarized light passing through the incident side polarization plate is converted in the polarization direction by 90 degrees in accordance with the twist of the liquid crystal molecules. After that, the light is emitted from the panel and passes through the polarizing plate on the output side. As described above, the liquid crystal light valve for each color and the liquid crystal light valve for luminance signal are switched by each color signal or luminance signal to form an image corresponding to each color signal or luminance signal on the light valve. That is, the light passing through each liquid crystal light valve is modulated.

The color signal light valves 10R, 10B and 10G and the brightness signal light valve 11 used in the present embodiment are the same in the size and shape of the image forming section and the basic structure described above. However, they differ in the following points.

Light valves 10R, 10B for color signals,
10G has a smaller number of pixels, that is, a smaller number of non-linear elements (switching elements) to be manufactured than the brightness signal light valve 11. Further, the aperture ratio of the color signal light valve is set larger than that of the luminance signal light valve 11.

The number of pixels is the color signal light valve 10R, 1
0B, 10G and the high-definition luminance signal light valve 11 are the same, the area of the portion through which the incident light can pass and the area occupied by the active nonlinear element on the light valve (the area of the portion through which the incident light cannot pass) ) Ratio,
In other words, the aperture ratios of both are lowered, and the defect that the projected image becomes dark although the resolution is high is caused, and the manufacturing yields of both are deteriorated due to the increase in the number of nonlinear elements. . Both of them can achieve the point that the aperture ratio increases and the projected image becomes brighter with a small number of pixels having low resolution, but the resolution becomes poor. In the present embodiment, as described above, as the color signal light valves 10R, 10B, and 10G, light valves each having a pixel area larger than that of the brightness signal light valve 11 are used. As a result, the amount of light emitted from the color signal light valves 10R, 10B, and 10G is increased because the aperture ratio is improved, and a bright color signal image can be projected. Further, since the projection image of the high-definition brightness signal projected from the high-definition brightness signal light valve 11 is superimposed on the color projection image projected from the color signal light valve, a bright and high-definition projection image is obtained. It will be possible to project.

As described above, the light valve 1 for each color signal
Since a secondary real image of the exit surface of the integrator 2 is formed on 0R, 10B, 10G to achieve critical telecentric illumination, the liquid crystal light valves 10R, 10B, 10
Contrast unevenness of the projected image due to the angle characteristic of G (that is, contrast unevenness caused by the difference in the modulation characteristic of the light valve due to the fact that the incident angle of the principal ray on the light valve differs depending on the location) is not caused. Absent.

Color signal light valves 10R, 10G, 1
The emitted light from 0B is the color signal light valves 10R and 10R with the principal rays maintaining the telecentricity.
The light is incident on a cross dichroic prism 7 which is a color combining optical system arranged in the vicinity of the exit ports of G and 10B, and color combination is achieved by the dichroic film forming the cross dichroic prism 7, and the chief ray maintains telecentricity. The light is emitted from the prism 7 as it is. That is, the cross dichroic prism 7 is the projection lens 1
The chief ray determined by the 06 aperture stop is arranged at a position having telecentricity. The dichroic film forming the cross dichroic prism 7 has different color combination characteristics depending on the angle of the incident light ray, but since the telecentricity with respect to the principal ray is ensured, the problem of color shading of the combined light, that is, color shading does not occur. . The light valves 10R, 10G, 10B
Since the light emitted from is the light obtained by converting the polarization direction of the first polarized light transmitted through the polarization beam splitter 3 by 90 ° by the half-wave plate 110, as described above, the cross dichroic S-polarized light is incident on the surface of the prism 7 on which the dichroic film is formed, so that the color combining characteristic of the dichroic prism 7 is improved.

Cross dichroic prism 7 for color combination
Similarly, the main light ray is incident on the polarization beam splitter 9 as a polarization combining optical system while the main ray maintains the telecentricity, and is combined with the emission light from the brightness signal light valve 11 by the polarization beam splitter 9. To be done.

As described above, the second polarized light that is polarized and separated by the polarization beam splitter 3 for polarization separation is arranged at a position where the relay lens 101 forms a 1 × real image of the exit surface of the integrator 2. The illuminated brightness signal light valve 11 is critically illuminated. In addition, this second
The polarized light of (1) achieves telecentric illumination for the brightness signal light valve 11 because the principal ray is parallel to the optical axis. From this, the light valve 10 for color signals
Similar to R, 10G, and 10B, the uneven contrast caused by the incident angle of the chief ray does not occur.

The brightness signal light valve 11 has a larger number of pixels and higher definition than the color signal light valves 10R, 10G and 10B as described above, but the size of the non-linear switching element that can be formed on the light valve. Has a limit, the aperture ratio is inferior to the color signal.
With the brightness signal light valve 11, the polarization direction is 9
The light emitted after being converted by 0 degrees is transmitted through the half-wave plate 111 while the principal ray maintains the telecentricity, and the polarization direction is converted by 90 degrees again.
1, and the principal ray enters the polarization beam splitter 9 for polarization combination while maintaining the telecentricity. The light emitted from the optical path length correction member 11 and the color combined light emitted from the color combining cross dichroic prism 7 are polarized and combined by the polarization beam splitter 9, and the combined light is projected onto a screen (not shown) by the projection lens 106. Projected on.

In the present embodiment, the optical path length correction member 8 is
This is a rectangular parallelepiped transparent optical member having a predetermined refractive index, and has a conjugate property with the image on the screen with respect to the projection lens 106 that the brightness signal light valve 11 and the color signal light valve 10 are connected.
It is arranged to secure between R, 10G and 10B. That is, the optical path length correction member 8 matches the optical path length from the brightness signal light valve 11 to the projection lens 106 with the optical path length from the color signal light valves 10R, 10G, and 10B to the projection lens 106. In the present embodiment, the polarization beam splitter 9 for polarization combination is also arranged in a position where the principal ray has telecentricity, and the incident angle characteristic of the principal ray of the polarization separation film for performing polarization combination in the polarization beam splitter 9 is set. It is possible to eliminate the uneven contrast caused by.

Although one embodiment of the present invention has been described above, the present invention is not limited to this embodiment.

For example, although the cross dichroic mirror is used as the color separation optical system in the embodiment of the present invention, a cross dichroic prism may be used instead. However, the cross dichroic prism has a larger difference in color separation characteristics with respect to the polarization direction of the incident polarized light than the cross dichroic mirror, and it is better to avoid incidence in the P polarization direction. For this reason, before entering the cross dichroic prism, the polarization direction is not converted by the ½ wavelength plate 110 as in the present embodiment, but is made to enter in the S polarization direction, and thereafter, for each color light. 1
It is preferable to dispose a / 2 wavelength plate to convert the polarization direction so that the light is incident on the combining dichroic prism 7 in the S polarization direction.

Further, although the cross dichroic prism is used as the color combining optical system in this embodiment, it goes without saying that a cross dichroic mirror may be used instead.

Further, in the present embodiment, the cross-sectional shape and size of the integrator which makes the light from the light source incident are determined by the used color signal light valves 10R, 10G ,.
10B, the shape and size of the image forming portion of the light valve 11 for brightness signal were the same. However, in this case, when the light valves 10R, 10G, 10B, and 11 become large, it becomes necessary to make the integrator 2 large in proportion to the cross-sectional shape thereof, but the production of a large integrator leads to cost increase. However, it is difficult to manufacture. In such a case, the cross-sectional shape of the integrator is reduced proportionally to the image forming portion of the light valve using the relay lens 101, and the relay lens 101 is configured as an enlarged relay lens. The size of the image is changed to the light valve 10R, 1
It may be enlarged so as to be substantially the same as the image forming portions of 0G, 10B, and 11. Further, the integrator is not limited to the rod integrator, for example,
A fly eye integrator may be used.

In the present embodiment, the light emitted from the integrator is made incident on the first relay optical system consisting of the single relay lens 101, but two illumination lenses are used as the first relay optical system. Types of relay optics may be used. Further, the second, third and fourth relay optical systems arranged between the color separation optical system and the light valves 10R, 10G and 10B for the respective colors are also provided immediately after the color separation optical system and the light valves 10R, 10G ,. A relay optical system may be configured by each field lens arranged immediately before 10B and a relay lens arranged between the field lenses.

[0058]

As described above, according to the present invention,
The polarization separation optical system, the color separation optical system, the color combining optical system, and the polarization combining optical system are all arranged at positions where the chief ray has telecentricity, so that the projected image can be made brighter while the projected image It is possible to eliminate uneven contrast and color shading.

Further, according to the present invention, the light valves for the respective color signals and the light valves for the luminance signals are provided with telecentric illumination, so that the uneven contrast due to the angular characteristic of each light valve can be eliminated.

Further, according to the present invention, by making the aperture ratio of the brightness signal light valve smaller than that of the color signal light valve, it is possible to project a high-definition and bright projection image.

[Brief description of drawings]

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

FIG. 2 is an optical path diagram in the YZ section in FIG. 1 of the projection type display device shown in FIG.

FIG. 3 is a schematic configuration diagram showing a conventional projection display device.

[Explanation of symbols]

1 Light Source 2 Rod Integrator 3 Polarization Separation Optical System (Polarization Beam Splitter) 4 Color Separation Optical System (Cross Dichroic Mirror) 5R, 5G, 5B, 6R, 6G, 6B Reflection Mirror 7 Color Synthesizing Optical System (Dichroic Prism) 8 Optical Path Length Correcting member 9 Polarization synthesizing optical system (polarizing beam splitter) 10R, 10B, 10G Light valve for color signal 11 Light valve for brightness signal 101 Relay lens 102R, 103R, 102G, 103G, 102B,
103B lens 104R, 105R, 104G, 105G, 104B,
105B lens 106 projection lens 110,111 1/2 wavelength plate

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Internal reference number FI Technical display location G09F 9/00 360 G09F 9/00 360D H04N 9/31 H04N 9/31 C (72) Inventor Hattori Tetsuo 3 2-3 Marunouchi, Chiyoda-ku, Tokyo Nikon Head Office

Claims (10)

[Claims] 1. A polarization separation optical system that separates light from a light source into a first polarization light and a second polarization light, and the first polarization light separated by the polarization separation optical system into a first polarization light and a second polarization light. A color separation optical system that separates the first, second and third color lights into first, second and third color lights; and a first and second color separation optical system that modulates the color separated first, second and third color lights based on predetermined color signals, respectively. And the third, third, and third color signal light valves are modulated by the first, second, and third color signal light valves and emitted from the first, second, and third color signal light valves, respectively. A color combining optical system that combines light, a light valve for a luminance signal that modulates the second polarized light that has been polarized and separated by the polarization separating optical system based on a predetermined luminance signal, and the color combining optical system. Modulated by color-combined light and the light signal light valve And a projection optical system for projecting the light combined by the polarization combining optical system, and a polarization combining optical system for combining the light emitted from the brightness signal light valve. The polarization separation optical system, the color separation optical system, the color combination optical system, and the polarization combination optical system are arranged at a position where the chief ray determined by the aperture stop of the projection optical system has telecentricity. Projection display device. 2. The first, second and third color signal light valves and the brightness signal light valve are arranged at positions where a chief ray determined by an aperture stop of the projection optical system has telecentricity. The projection type display device according to claim 1, wherein the first, second and third color signal light valves and the brightness signal light valve are illuminated by telecentric illumination. 3. A polarization splitting optical system that splits light from a light source into first polarized light and second polarized light, and first polarized light split by the polarization splitting optical system. Color separation optical systems for performing color separation into first, second and third color lights, and first and second for modulating the color separated first, second and third color lights respectively based on predetermined color signals. And a third color signal light valve, and modulated by the first, second, and third color signal light valves, and emitted from the first, second, and third color signal light valves, respectively. A color combining optical system for color-combining light; a brightness signal light valve for modulating the second polarized light polarized and separated by the polarization separating optical system based on a predetermined brightness signal; and a color combining optical system. Modulated by color-synthesized light and the brightness signal light valve And a projection optical system for projecting the light combined by the polarization combining optical system, and a polarization combining optical system for combining the light emitted from the brightness signal light valve. An integrator on which light from the light source is incident and a first relay optical system for guiding light emitted from the integrator to the polarization separation optical system are provided between the light source and the polarization separation optical system, The brightness signal light valve is a real image of the exit surface of the integrator formed by the first relay optical system, and is the second image separated by the polarization separation optical system.
Is disposed at a position where a real image is formed by the polarized light, and color separation is performed by the color separation optical system between the color separation optical system and the first, second, and third color signal light valves. The second, third, and third images for forming the real images of the exit surface of the integrator by the generated first, second, and third color lights on the first, second, and third color signal light valves, respectively. 4. A projection type display device in which four relay optical systems are respectively arranged. 4. The projection display device according to claim 3, wherein the integrator is a rod integrator. 5. The polarization splitting optical system and the polarization combining optical system each include a polarization beam splitter, and the color separation optical system and the color combining optical system each include a cross dichroic prism or a cross dichroic mirror. The projection display device according to claim 1, wherein the projection display device is a display device. 6. An optical path length from the brightness signal light valve to the projection optical system is provided between the brightness signal light valve and the polarization combining optical system, and the optical path length from the brightness signal light valve to the projection optical system is set to the first, second and third colors. 6. The projection type display device according to claim 1, further comprising an optical path length correcting member arranged to substantially match an optical path length from a signal light valve to the projection optical system. 7. A polarization splitting optical system that splits light from a light source into a first polarized light and a second polarized light, and a first polarized light that is polarized and split by the polarization splitting optical system. Color separation optical systems for performing color separation into first, second and third color lights, and first and second for modulating the color separated first, second and third color lights respectively based on predetermined color signals. And a third color signal light valve, and modulated by the first, second, and third color signal light valves, and emitted from the first, second, and third color signal light valves, respectively. A color combining optical system for color-combining light; a brightness signal light valve for modulating the second polarized light polarized and separated by the polarization separating optical system based on a predetermined brightness signal; and a color combining optical system. Modulated by color-synthesized light and the brightness signal light valve And a projection optical system for projecting the light combined by the polarization combining optical system, and a polarization combining optical system for combining the light emitted from the brightness signal light valve. The shape and size of the image forming portion of the first, second and third color signal light valves and the shape and size of the image forming portion of the brightness signal light valve are substantially the same. The projection display device is characterized in that the aperture ratio of the light valve is smaller than the aperture ratios of the first, second and third color signal light valves. 8. The projection display device according to claim 7, wherein the number of pixels of the brightness signal light valve is larger than the number of pixels of the first, second and third color signal light valves. . 9. The first, second and third color signal light valves and the luminance signal light valve are arranged at positions where a chief ray determined by an aperture stop of the projection optical system has telecentricity. 9. The projection display device according to claim 7, wherein the first, second and third color signal light valves and the brightness signal light valve are illuminated by telecentric illumination. 10. The polarization separation optical system, the color separation optical system, the color combination optical system, and the polarization combination optical system are located at a position where a chief ray determined by an aperture stop of the projection optical system has telecentricity. The projection display device according to claim 7, wherein the projection display device is arranged.