JPH09211384A - Projection device - Google Patents

Abstract

(57) [PROBLEMS] To provide a projection device capable of improving the utilization efficiency of light from a light source to significantly improve the brightness and brightness of a projected image and at the same time reduce the cost. SOLUTION: A polarization separation optical system 3 for polarization-separating light from a light source 1 into a first polarization and a second polarization, a color separation optical system 5 for color-separating the first polarization, and a color separation by a color separation optical system. A plurality of color signal light valves 8R, 8G, 8B provided at positions where the separated light is guided, and a color combining optical system 9 for combining the light modulated by the plurality of color signal light valves.
A brightness signal light valve 13 provided at a position where the second polarized light is guided, a combining optical system 14 for combining light from the color combining optical system and light from the brightness signal light valve,
A projection lens 107 for projecting light from the combining optical system is provided, and the polarization splitting optical system is arranged at a position where a principal ray defined by the projection lens 107 intersects the optical axis.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus for projecting an image formed on a liquid crystal light valve onto a screen, and more particularly to a plurality of images formed on the liquid crystal light valve for a plurality of color components. The present invention relates to a device for illuminating with the illumination light of the color component of, and for synthesizing these images to project the synthetic image by a projection lens.

[0002]

2. Description of the Related Art Light from a light source is color-separated into R, G, and B lights by a three-color separation optical system, and the incident light of the R, G, and B lights separated by a light valve using a liquid crystal is signaled. 2. Description of the Related Art There is known a projection device that performs modulation, color-modulates the modulated lights emitted from these light valves, and projects them by a projection lens. A typical example of this device is shown in FIG.

In FIG. 3, the light source light including the R, G, B lights emitted from the lamp 301 is converted into a substantially parallel light flux by a concave mirror 302 and a condenser lens 303 arranged in the back, and is incident on a color separation optical system. To do. The color separation optical system includes a blue light (B light) reflection dichroic mirror 304 and a green light (G light).
Light) reflection dichroic mirror 305 and
B B reflected by the light reflection dichroic mirror 304
The light is reflected again by the mirror 307 to enter the B light liquid crystal light valve 311 and the G light reflected by the G light reflecting dichroic mirror 305 enters the G light liquid crystal light valve 310. Then, the red color (R light) that has passed through the dichroic mirror 305 is reflected by the mirrors 306 and 308 and is reflected by the R light liquid crystal light valve 30.
9 is incident. Each color light incident on each liquid crystal light valve is modulated based on the video signal of each color. That is, the video signal of each color is converted into an image having a transmittance distribution on each liquid crystal light valve. The lights emitted from these light valves enter a dichroic prism 312 having a R-light and B-light reflecting dichroic film as a combining optical system, and are combined into three colors. And is projected by a projection lens 313 on a screen (not shown) in an enlarged manner.

In this conventional example, the dichroic mirror 3
Although 04 and 305 are configured to be parallel to each other, a so-called cross dichroic mirror in which these dichroic mirrors 304 and 305 are arranged in an X shape is also known as a conventional example. However, FIG.
In the prior art example, about half of the light that enters the liquid crystal light valve is absorbed by the polarizing plates that form a crossed Nicols sandwiching the liquid crystal panel that constitutes the liquid crystal light valve from both sides and is discarded as heat. As described above, the conventional example of FIG. 3 has a problem that the projection image cannot be brightened as a result.

As a conventional projection device, for example, one shown in FIG. 4 is also known. In the conventional example shown in FIG. 4, the light source light from the light source 201 is polarized and separated by a polarization beam splitter (PBS) 202. One of the polarized and separated lights is the dichroic mirrors 210 and 215 as the three-color separation optical system as in the above-mentioned conventional device.
After being separated into three colors by the light valve 20 for each color
6, 207 and 208 are modulated according to the color signal. After that, the light valves for each color 206, 207, 20
The light emitted from 8 is combined by dichroic mirrors 214 and 218 as a three-color combining optical system.

On the other hand, the other polarized light which is polarized and separated by the PBS 202 enters a light valve for brightness signal 204 and is modulated according to the brightness signal. After that, the lights from the three-color combining optical systems 214 and 218 and the light from the brightness signal light valve are combined by the combining PBS 209 and then projected onto a screen (not shown) via the projection lens 219.

[0007]

The polarizing beam splitter used in the above-mentioned projection apparatus is generally one in which a dielectric multilayer film is provided on a supporting optical member such as glass. Here, if the size of the polarization beam splitter becomes too large, the cost of the supporting optical member having uniform optical characteristics will increase significantly, and it will be difficult to obtain it. In particular, when a prism type polarization beam splitter is used, the thickness of the supporting optical member placed in the optical path increases, which further increases the cost.

Therefore, it is an object of the present invention to provide a projection apparatus capable of improving the utilization efficiency of light from a light source to significantly improve the brightness and luminance of a projected image and at the same time reduce the cost. To

[0009]

In order to achieve the above-mentioned object, a projection apparatus according to one 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. System, a color separation optical system for color-separating the first polarized light, a plurality of color signal light valves provided at a position where the light separated by the color separation optical system is guided, and a plurality of color signal light valves A color synthesizing optical system for synthesizing light modulated by, a brightness signal light valve provided at a position where the second polarized light is guided, light from the color synthesizing optical system, and light from the brightness signal light valve. A combination optical system for combining and a projection lens for projecting light from the combination optical system are provided, and a polarization separation optical system is arranged at a position where a principal ray defined by the projection lens intersects the optical axis.

[0010] In a preferred embodiment of the present invention,
The color separating optical system and the color synthesizing optical system are provided at positions where the chief ray maintains the telecentricity. In a preferred embodiment of the present invention, the synthetic optical system is provided at a position where the chief ray maintains the telecentricity. In a preferred embodiment of the present invention, an illumination relay optical system that has an integrator, a front group and a rear group between the light source and the color separation optical system and guides light from the integrator to the color separation optical system. And the polarization separation optical system is disposed in the optical path between the front group and the rear group.

In addition to the above-mentioned structure, between the color separation optical system and the plurality of color signal light valves, there is provided a color signal relay optical system for guiding the light from the color separation optical system to the plurality of color signal light valves. A system is provided, and a rear group of a brightness signal relay optical system for guiding light from the polarization separation optical system to the brightness signal light valve is provided between the polarization separation optical system and the brightness signal light valve. Therefore, it is preferable that the front group of the relay optical system for the luminance signal is configured to be the front group of the relay optical system for illumination.

In addition to the above configuration, the integrator forms a surface light source, the illumination relay optical system forms an image of the surface light source, and is a telecentric optical system on the image side of the surface light source. Relay optical system is an optical system that forms a secondary image of a surface light source on a plurality of color signal light valves and is telecentric on the secondary image side. The luminance signal relay optical system is an image of the surface light source. Is preferably formed on the light valve for the brightness signal, and is a telecentric optical system on the surface light source side.

In a preferred embodiment of the present invention,
The plurality of light valves for color signals include a light valve for R light, a light valve for G light, and a light valve for B light,
The relay optical system for color signals guides the R component light from the color separation optical system to the light valve for R light and the relay optical system for R light and the G component light from the color separation optical system to the light valve for G light. It is configured to have a G light relay optical system and a B light relay optical system that guides the B component light from the color separation optical system to the B light light valve.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, referring to FIG. 1 and FIG.
An embodiment according to the present invention will be described. FIG. 1 is a perspective view for explaining the overall configuration of a projection device according to an embodiment of the present invention, and adopts an XYZ coordinate system for the sake of simplicity. FIG. 2 shows the YZ of the projection device shown in FIG.
FIG. 6 is an optical path diagram in a plan view, in which solid lines indicate the outermost marginal rays of the off-axis light flux, and broken lines indicate the principal rays of the off-axis light flux.
The coordinate system in FIG. 2 corresponds to that in FIG.

In FIG. 1, light from a light source 1 including a lamp (not shown) and an elliptic mirror provided so that the lamp has a first focus passes through an infrared absorption filter (not shown) and an ultraviolet absorption filter (not shown). The light is focused on the incident surface of the rod integrator 2 made of a prism-shaped transparent optical member. The light that has entered the rod integrator 2 is repeatedly reflected by the inner surface of the rod integrator 2 and exits from the exit surface that faces the entrance surface. Here, a surface light source having a uniform light intensity distribution is formed on the exit surface. In other words, the exit surface is superposedly illuminated with light from virtual images of a plurality of light sources formed at the position of the entrance surface by the internal reflection of the rod integrator 2.

Next, the light from the exit surface of the rod integrator 2 travels along the -Z direction in the figure, and the first and second lights are emitted.
The light enters the illumination relay optical system including the illumination lenses 101 and 102. In this illumination relay optical system, a first illumination lens 101 having a focal length f1 as a front group and a second illumination lens 102 having a focal length f2 as a rear group are separated by a distance f1 + f2.
That is, that is, that is, the rear focal position of the first illumination lens 101 and the front focal position of the second illumination lens 102 match.

The first polarization beam splitter 3 is provided at the pupil position of the illumination relay optical system, that is, at the position where the rear focal position of the first illuminating lens 101 and the front focal position of the second illuminating lens 102 coincide with each other. Has been. Of the light from the first illumination lens 101 that enters the first polarization beam splitter 3, the first polarization component that is a P polarization component (linear polarization whose vibration direction is ± Y direction in the drawing) with respect to the polarization beam splitter 3 is After passing through the polarization beam splitter 3, the polarization component in the state where the polarization direction is rotated by 90 degrees after passing through the half-wave plate 4 arranged on the exit side (the vibration direction is ±
The linearly polarized light in the X direction) is incident on the second illumination lens.

The linearly polarized light that has passed through the illumination lens 102 is incident on a cross dichroic mirror 5 in which an R light reflection dichroic mirror 5R and a B light reflection dichroic mirror 5B are combined in an X type. Here, the R component light is R
The light reflection dichroic mirror 5R reflects in the -X direction in the figure, and the B component light is reflected in the B light reflection dichroic mirror 5B in the + X direction in the figure. And
The G component light passes through the R light reflection dichroic mirror 5R and the B light reflection dichroic mirror 5B and travels in the -Z direction in the figure.

At the rear focal position of the second illumination lens 102 in the optical paths of the R component light, the G component light and the B component light separated by the cross dichroic mirror 5, the image of the exit surface of the rod integrator 2 is shown in each color. It is formed for each component light. Now, the G component light will be described with reference to FIG. 2 showing the optical path of the G component light of each color component light. The G component light that has passed through the cross dichroic mirror 5 forms an image of the G component light on the exit surface of the rod integrator 2 at a position separated from the second illumination lens 102 by the optical path length f2. The G component light from this image is reflected by the bending mirror 6G and travels along the -Y direction in the drawing. afterwards,
The G component light passes through the lens 103G, is then reflected by the folding mirror 7G, is deflected in the + Z direction in the drawing, and passes through the lens 104G. Here, the lenses 103G and 1
04G constitutes a relay optical system for G light and has a focal length f2.
Lens 103G and the lens 104G having the focal length f1 have a distance f1 + f2, that is, the lens 103G
The rear focal point and the front focal point of the lens 104G are arranged so as to coincide with each other.

The G component light from the G light relay optical system travels along the + Z direction and reaches the G light liquid crystal light valve 8G as a color signal light valve. The G light liquid crystal light valve 8G is arranged at a distance f1 from the G light relay optical system, and an image formed by the G component light on the exit surface of the rod integrator 2 is formed here.

Returning to FIG. 1, the R component light reflected in the -X direction by the cross dichroic mirror 5 is
Similar to the G component light, an image of the R component light on the exit surface of the rod integrator 2 is formed at a position away from the second illumination lens 102 by the optical path length f2. The R component light from this image is reflected by the bending mirror 6R and travels along the -Y direction in the figure. After that, the R component light is reflected by the lens 103R.
After passing through, the light is reflected by the bending mirror 7R, is deflected in the + Z direction in the figure, and passes through the lens 104R. Here, the lenses 103R and 104R form a relay optical system for R light, and the lens 103R having the focal length f2 and the lens 104R having the focal length f1 have a distance f1 + f2, that is, the rear focus and the lens of the lens 103R. 104
It is arranged so that the front focus of R matches.

The R component light from the R light relay optical system travels along the + X direction and reaches the R light liquid crystal light valve 8R as a color signal light valve. The R light liquid crystal light valve 8R is arranged at a distance f1 from the R light relay optical system, and an image formed by the R light component on the exit surface of the rod integrator 2 is formed here.

The B component light reflected by the cross dichroic mirror 5 is, like the G component light, at the position B away from the second illuminating lens 102 by the optical path length f2. An image is formed by the component light. The B component light from this image is reflected by the bending mirror 6B and travels along the -Y direction in the figure. After that, the B component light passes through the lens 103B and then the bending mirror 7
It is reflected by B and is deflected in the + Z direction in the figure, and the lens 1
Pass 04B. Here, the lenses 103B and 104
B constitutes a relay optical system for B light, and the lens 103B having the focal length f2 and the lens 104B having the focal length f1 have an interval f1 + f2, that is, the rear focus of the lens 103B and the front focus of the lens 104B. Arranged to match.

The B component light from the B light relay optical system travels along the + X direction and reaches the B light liquid crystal light valve 8B as a color signal light valve. The B-light liquid crystal light valve 8B is arranged at a distance f1 from the B-light relay optical system, and an image formed by the B-light component on the exit surface of the rod integrator 2 is formed here.

Thus, an image of the exit surface of the rod integrator 2 having a uniform light intensity distribution is formed on the liquid crystal light valve for each color. That is, the liquid crystal light valve for each color is critically illuminated by a uniform surface light source. Further, in the embodiment, the illumination relay optical systems 101 and 102 form an image of the exit surface of the rod integrator 2 at f2 / f1 times, and each color relay optical system produces this image at f1 / f2 times. Reimage on the liquid crystal light valve. That is, an equal-magnification image of the exit surface of the rod integrator 2 is formed on each liquid crystal light valve. As described above, in the embodiment, since the exit surface of the rod integrator 2 and the liquid crystal light valve for each color are arranged in a conjugate manner, and the magnification relationship is the same, the exit surface of the rod-shaped rod integrator 2 is The vertical and horizontal sizes are determined so that they have the same size and shape as the image display surface of each liquid crystal light valve.

In the projection apparatus according to the embodiment shown in FIGS. 1 and 2, the lens 10 of the R optical relay optical system is used.
3R, the lens 103G of the G light relay optical system, and the lens 103B of the B light relay optical system have the same focal length f2.
4R, the lens 104G of the relay optical system for G light, and the lens 104B of the relay optical system for B light are the same lens having the focal length f1. Further, from the cross dichroic mirror 5 which is a color separation optical system to the liquid crystal light valve 8 for each color.
The optical path lengths up to R, 8B, and 8G are substantially the same.

The liquid crystal light valves 8R, 8B and 8G for each color will be described. Each liquid crystal light valve has a structure in which a liquid crystal panel is sandwiched between two polarizing plates that form a crossed Nicols. The liquid crystal panel includes a transparent glass substrate, and a transparent glass substrate and a glass plate on the glass substrate in order from the light incident side. It is composed of an active non-linear element (for example, a TFT) that selectively switches the formed grid-like pixel, an electrode that is combined with the active non-linear element, a liquid crystal layer, a counter electrode, and a transparent glass substrate. When the active element switches the electrode by the color signal for each color,
A voltage is applied between the counter electrodes facing this electrode, and the electric field causes the molecules of the liquid crystal to be aligned parallel to each other and perpendicular to the substrate. Therefore, the polarized light from the incident side polarizing plate passes through the liquid crystal panel as it is, and is absorbed by the emitting side polarizing plate forming the crossed Nicols. Here, a twisted structure is maintained in a portion that is not selected by the active element, and in this case, the polarization direction of the polarized light from the incident side polarization plate is changed by 90 degrees in accordance with the twist of the liquid crystal and is emitted from the panel. And passes through the exit side polarizing plate. As described above, each liquid crystal light valve is switched by each color signal to form an image corresponding to each color signal thereon, that is, the light passing through each liquid crystal light valve is modulated.

Now, the liquid crystal light valves for each color 8R, 8
On the exit side of B and 8G, the R light reflection dichroic film 9R
A cross dichroic prism 9 in which four right angle prisms are combined is provided so that the B light reflection dichroic film 9B and the B light reflection dichroic film 9B are X-shaped. The G component light modulated by the G light liquid crystal light valve 8G travels in the + Z direction in the drawing and passes through the R light reflection dichroic film 9R and the B light reflection dichroic film 9B. The R component light modulated by the R light liquid crystal light valve 8R is +
Progressing in the X direction, R light reflection dichroic film 9R
The B component light reflected by the liquid crystal light valve 8B for B light in the + Z direction travels in the -X direction in the figure, and is directed in the + Z direction by the B light reflection dichroic film 6B. Is reflected. That is, by the cross dichroic mirror 5, three directions (R component light is + X direction, G
Each color component light separated into the component light in the -Z direction and the B component light in the -X direction passes through each liquid crystal light valve and then is in the opposite direction to the above three directions (R component light is in the -X direction, G direction). The component light is +
The Z component light and the B component light are incident on the cross dichroic prism 9 in the + X direction), and the cross dichroic mirror 5
The respective color component lights are combined and emitted from the cross dichroic prism 9 in the opposite direction (+ Z direction) to the incident direction (−Z direction). At this time, the R light liquid crystal light valve 8
The R component light from R is linearly polarized light vibrating in the ± Y directions, and the B component light from the B light liquid crystal light valve 8B is ± Y.
The linearly polarized light that vibrates in the directions, and the G component light from the liquid crystal light valve for G light 8G is the linearly polarized light that vibrates in the ± Y directions. As described above, in the embodiment, the distance between the polarization beam splitter 3 and the cross dichroic mirror 5 is 1
Since the / 2 wavelength plate 4 is provided, the linearly polarized light from the liquid crystal light valve of each color can be S-polarized with respect to the dichroic films 9R and 9B of the cross dichroic prism 9, and the dichroic films 9R and 9B of The spectral characteristics can be improved.

On the exit side (+ Z direction side) of the cross dichroic prism 9, the combined light relay optical system 105 is provided.
Is provided, and the light that has passed through the synthesizing relay optical system 105 travels in the + Z direction, and the bending mirror 1
It is deflected at 0 and travels in the + Y direction to form the images of the liquid crystal light valves 8R, 8B, 8G for each color at the same position, that is, the liquid crystal light valves 8R, 8B for each color are combined by the combining relay optical system. An 8G composite image I is formed. The combining relay optical system 105 includes a lens 105 ′ having a focal length f3 and a focal length f, as shown in FIG.
It is possible to use the lens 105 ″ of No. 4 and the lens 105 ″ arranged at an interval of f3 + f4.

The second polarized component reflected by the polarization beam splitter 3 (linearly polarized light whose vibration direction is ± X direction in the figure) proceeds along the -Y direction in the figure and has the third focal length f2. After passing through the illumination lens 106, the folding mirror 1
At 2, the light is reflected in the + Z direction in the figure. Here, the third
The illumination lens 106 has an optical path length of f1 + f2 with the first illumination lens 101, that is, the rear focus position of the first illumination lens 101 and the front focus position of the third illumination lens 106 match. Are arranged as follows. The light valve 13 for luminance signal is arranged at the rear focal position of the third illuminating lens 106. Here, the brightness signal relay optical system that forms an image of the exit end of the rod integrator 2 on the brightness signal light valve 13 is the first illumination lens 101 of the illumination relay optical system as the front group.
And a third illumination lens 106 as a rear group.

Here, the brightness signal relay optical system for forming the image of the rod integrator 2 on the brightness signal light valve 13 is the first illumination lens 101 of the illumination relay optical system as the front group and the rear group as the rear group. The third illumination lens 106 of the luminance signal relay optical system is used, and the first illumination lens 101 is shared by the illumination relay optical system and the luminance signal relay optical system. Here, in the projection apparatus according to the second embodiment, the same lens is used for the second illumination lens 102 of the illumination relay optical system and the third illumination lens 106 of the luminance signal relay optical system.

The brightness signal light valve 13 is structurally similar to the color signal light valves 8R, 8B, and 8G described above, but the size thereof is different from that of the color signal light valve 8.
It is configured to be larger than R, 8B, and 8G and have a large number of pixels. The above relay optical system 101, 1
Due to 06, an enlarged image of the exit surface of the rod integrator 2 is formed on the brightness signal light valve 13.
At this time, the magnification of the magnified image on the luminance signal light valve 13 is given by f2 / f1. Therefore, the focal lengths of the first to third illumination lenses and the focal lengths f1 and f2 of the lenses of each color relay optical system are the same as those of the brightness signal light valve 13 and the liquid crystal light valves 8R, 8B and 9G for each color. It may be determined by the ratio of.

Luminance signal light valve 13 exit side (+
On the Z direction side), a polarization beam splitter 14 as a combining optical system is arranged. Luminance signal light valve 1
The light emitted from 3 is linearly polarized light having a vibration direction of ± Y directions in the figure, and is P-polarized with respect to the polarization beam splitter 13. Therefore, this light is the polarization beam splitter 13
Through the projection lens 107 and enters the projection lens 107 located on the exit side.

On the other hand, from the combined image I formed by the combining relay optical system 105, linearly polarized light having a vibration direction of ± Z directions in the figure advances along the + Y direction. This linearly polarized light passes through the half-wave plate 11 and has a polarization direction of 90 degrees.
After rotating by ± degrees, the polarization beam splitter 13
Incident on. Since this light becomes S-polarized light with respect to the polarization beam splitter 13, it is reflected here, travels along the + Z direction in the drawing, and enters the projection lens 107. Here, the light valve 13 for the luminance signal and the composite image I are at positions conjugate with each other with respect to the projection lens 107.

The projection lens 107 has an aperture stop (not shown), and the polarization beam splitter 1 has a larger aperture than the aperture stop.
In this configuration, the aperture stop is arranged at the rear focal point of the lens unit located on the third side (the aperture stop side is the rear side). This aperture stop determines the principal ray of the optical system of the projection device, and the principal ray becomes parallel to the optical axis between the polarization beam splitter 13 and the projection lens 107. That is, the projection lens system 107 is an optical system that is telecentric on the polarization beam splitter 13 side.

As shown in FIG. 2, in the projection apparatus according to the embodiment, the optical path between the exit surface of the rod integrator 2 and the illuminating lens 101, the illuminating lens 102 and the G light relay lens 103G are provided. Between the lens 104G of the G light relay lens and the lens 105 'of the combining relay optical system, the optical path between the lens 105 "of the combining relay optical system and the projection lens 107, and the third lens. In the optical path between the illumination lens 106 and the projection lens 107, the chief ray determined by the aperture stop of the projection lens system 105 becomes parallel to the optical axis.

Although not shown in FIG. 2, the optical path between the illumination lens 102 and the R light relay lens 103R, the R light relay lens 104R, and the combining relay optical system lens 105 are provided. , The optical path between the lens and the illumination lens 102 and the B light relay lens 103B
Optical path between and and lens 104B of relay lens for B light
Also in the optical path between the lens and the lens 105 ′ of the combining relay optical system, the chief ray determined by the aperture stop of the projection lens system 107 becomes parallel to the optical axis. In other words, the illumination relay optical systems 101 and 102, the illumination relay optical system 1
01, 106, R optical relay optical system 103G, 104
The G and B light relay optical systems 103B and 104B, the G light relay optical systems 103G and 104G, and the combining relay optical system are double-sided telecentric optical systems.

Further, in the projection apparatus according to the embodiment, the chief ray between the first illumination lens 101 and the second illumination lens 102, in other words, between the first illumination lens 101 and the third illumination lens 106 is , Intersects the optical axis at the position of the polarization beam splitter 3 as the polarization separation optical system. As described above, the off-axis light flux determined by the diameter of the aperture stop of the projection lens has a principal ray that is the optical axis at any object height (the distance between the principal ray of the incident light flux and the optical axis in the direction perpendicular to the optical axis). It passes through the same area at the position intersecting with. That is, at the position where the chief ray intersects the optical axis, the diameter of the total luminous flux passing therethrough becomes the smallest. Therefore, in the projection device according to the embodiment, since the polarization beam splitter 3 is arranged at this position, the size of the polarization beam splitter 3 can be minimized.

In a multi-layer film filter such as a dichroic mirror or a dichroic prism, its spectral characteristic has an angle dependence. Therefore, if the incident angle of the chief ray on the multilayer filter determined by the projection lens is not constant at any position of the multilayer filter, the spectral characteristics of the multilayer filter will differ for each chief ray and May cause color shading. Therefore, it is preferable that the color separation optical system, the color combining optical system, and the combining optical system are provided at positions where the principal rays are parallel to the optical axis, that is, positions where the principal rays maintain telecentricity. In addition, since the liquid crystal light valve also has angle dependence, if the incident angle of the chief ray on the liquid crystal light valve differs depending on the location,
Due to this, the contrast of the projected image may be uneven, and therefore, the liquid crystal light valve is also preferably provided at a position where the chief ray maintains the telecentricity.

Therefore, in the projection apparatus according to the embodiment, in order to suppress color shading on the screen and unevenness of the contrast of the projected image, the cross dichroic mirror 5 as the color separation optical system and the color combination optical system are used. The cross dichroic prism 9, the color signal liquid crystal light valves 8R, 8G, and 8B and the brightness signal light valve are provided at positions where the principal rays maintain telecentricity, and color shading on the screen and the contrast of the projected image. The polarization beam splitter 3 which has less influence on the unevenness is arranged at a position where the principal ray intersects the optical axis, and the polarization beam splitter 3 itself is made compact to reduce the cost.

With this configuration, it is possible to project a full-color image with excellent image quality and high brightness, and to achieve cost reduction. In the projection device according to the embodiment shown in FIGS. 1 and 2, the first illumination lens 101 of the illumination relay optical system is used.
And lenses 104R, 104G, 1 of the relay optical system for each color
04B and the same type of lens having the focal length f1 and the second illumination lens 102 of the relay optical system for illumination, the third illumination lens 106 of the relay optical system for luminance signals, and the lenses 103R, 103G of the relay lenses for each color, 103B is composed of the same type of lens having a focal length f2. in this way,
Since the lenses constituting the illumination relay optical system, the luminance signal relay optical system, and the relay optical system for each color are shared, the cost can be reduced.

In the embodiment, the image of the liquid crystal light valve for each color and the image of the liquid crystal light valve for the brightness signal are formed on a screen (not shown), but the direction of the image on the screen is formed. Needless to say, the liquid crystal light valve for each color and the liquid crystal light valve for luminance signal are driven so as to be aligned with each color component light. In the projection device according to the embodiment shown in FIGS. 1 and 2, the synthesizing relay optical system 105 has been described as consisting of two lens groups, but instead, for example, the exit side of the cross dichroic prism 9 is used. Near (+ Z direction side)
It is also possible to include a field lens disposed in the above position, a field lens disposed in the vicinity of the composite image, and a lens group having a positive refractive power disposed between these two field lenses. Further, in the example of FIGS. 1 and 2, the half-wave plate 1 is provided in the optical path between the composite image I and the polarization beam splitter 14.
Although 1 is arranged, it may be arranged in the optical path between the composite image I and the bending mirror 10 instead. In this way, the half-wave plate 11 may be arranged in the optical path between the dichroic prism 9 as the color combining optical system and the polarization beam splitter 14 as the combining optical system. Also,
Half-wave plates 4 and 11 are half of the sheet type
A wave plate may be used, and in this case, it may be provided on the surfaces of the prism members such as the polarization beam splitters 3 and 14 and the dichroic prism 9.

In the example of FIGS. 1 and 2, the first and second illumination lenses 101 and 102 form an illumination relay optical system, but instead, they are sandwiched by two field lenses. You may comprise with the lens group of positive refracting power. In this case, when the polarization beam splitter 3 is arranged between the field lens on the cross dichroic mirror 5 side and the lens group having a positive refracting power, the same field lens as the above field lens is arranged in the optical path between the polarization beam splitters 3 and 14. To do. Further, when the polarization beam splitter 13 is arranged in the optical path between the positive refractive power lens group and the rod integrator 2, the positive refractive power lens group and the field are provided in the optical path between the polarization beam splitters 3 and 14. The same thing as the lens may be arranged. Even in this arrangement, it goes without saying that the polarization beam splitter 3 is arranged at a position where the principal ray intersects the optical axis.

Although the rod integrator is used in the above embodiment, a fly-eye lens may be applied instead. Further, instead of using the lamp and the elliptical mirror as the light source, the lamp, the parabolic mirror, and the spherical mirror can be used. In the embodiment shown in FIGS. 1 and 2, the chief ray is determined by the aperture stop of the projection lens system, but instead of / in addition to that, an aperture is formed at a position conjugate with the position equivalent to the aperture stop of the projection lens. It goes without saying that a diaphragm may be provided. For example, the first illumination lens 1
01 and the polarization beam splitter 3, between the lenses 103R, 103G and 103B of the relay optical system for each color and the bending mirrors 7R, 7G and 7B, and / or the aperture of the projection lens system 107 in the combining relay optical system. It may be provided at a position conjugate with the diaphragm equivalent position. By using an aperture stop provided in addition to such a projection lens system, it is possible to remove the internal reflected light and scattered light in the optical system of the projection device, improve the contrast of the projected image and prevent heating of the liquid crystal light valve. it can.

Further, in the embodiment, the field stop may be arranged at a position conjugate with the exit surface of the rod integrator 2. By providing such a field diaphragm,
It is possible to remove the internal reflected light and scattered light in the optical system of the projection device, improve the contrast of the projected image, and prevent heating of the liquid crystal light valve. As described above, the present invention is not limited to the above-described embodiment and can take various forms.

[Brief description of drawings]

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

FIG. 2 is an optical path diagram of the projection device according to the first embodiment.

FIG. 3 is a diagram showing a conventional projection device.

FIG. 4 is a diagram showing a conventional projection device.

[Explanation of symbols]

 1 Light Source 2 Rod Integrator 3 Polarizing Beam Splitter 4 1/2 Wave Plate 5 Cross Dichroic Mirror 5RR R Light Reflecting Dichroic Mirror 5B B Light Reflecting Dichroic Mirror 8R, 8B, 8G Light Valve for Color Signal 9 Dichroic Prism for Color Synthesis 13 Luminance Signal Light valve 14 Polarization beam splitter 105 Synthetic relay lens 107 Projection lens system

Claims (7)

[Claims] 1. A polarization splitting optical system for splitting light from a light source into first polarized light and second polarized light, a color splitting optical system for color splitting the first polarized light, and color splitting by the color splitting optical system. A plurality of color signal light valves provided at a position where the modulated light is guided, a color combining optical system that combines the light modulated by the plurality of color signal light valves, and a position where the second polarized light is guided. A light valve for luminance signal, a combining optical system for combining light from the color combining optical system and light from the light valve for brightness signal, and a projection lens for projecting light from the combining optical system. And the projection lens has an aperture stop, and the polarization separation optical system is arranged at a position where a chief ray defined by the aperture stop of the projection lens intersects the optical axis. 2. The projection apparatus according to claim 1, wherein the color separation optical system and the color combination optical system are provided at positions where the chief ray maintains telecentricity. 3. The projection apparatus according to claim 1, wherein the combining optical system is provided at a position where the chief ray maintains telecentricity. 4. Between the light source and the color separation optical system,
An integrator, a relay optical system for illumination that guides the light from the integrator to the color separation optical system having a front group and a rear group are provided, and the polarization separation optical system includes the front group and the rear group. The projection device according to any one of claims 1 to 3, wherein the projection device is arranged in an optical path between them. 5. A color signal relay optical system for guiding light from the color separation optical system to the plurality of color signal light valves between the color separation optical system and the plurality of color signal light valves. Is provided between the polarization separation optical system and the brightness signal light valve, and a rear group of brightness signal relay optical system for guiding the light from the polarization separation optical system to the brightness signal light valve. 5. The projection apparatus according to claim 4, wherein the front group of the relay optical system for luminance signal is the front group of the relay optical system for illumination. 6. The integrator forms a surface light source, the illumination relay optical system forms an image of the surface light source,
And an optical system telecentric on the image side of the surface light source, wherein the color signal relay optical system forms a secondary image of the surface light source on the plurality of color signal light valves, and Is a telecentric optical system on the side, the luminance signal relay optical system is an optical system that forms an image of the surface light source on the luminance signal light valve, and is a telecentric optical system on the surface light source side. The projection device according to claim 5. 7. The color signal light valves include an R light light valve, a G light light valve and a B light light valve, and the color signal relay optical system is the color separation optical system. An R-light relay optical system that guides the R-component light from the R-light to the R-light light valve, a G-light relay optical system that guides the G-component light from the color separation optical system to the G-light light valve, 7. The projection device according to claim 1, further comprising a B-light relay optical system that guides B-component light from the color separation optical system to the B-light light valve.