JP2000131649A - Reflection type projection optical system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To attain the reduction of the assembly man-hour of an optical system, the reduction of a manufacturing cost and the compactness of the optical system and also to prevent the color irregularity of an image formed by executing the separation and synthesis of a colored light beam by one colored light separating synthesizing means and executing the reflection and transmission of the polarization of each colored light beam by using three polarizing beam splitters exclusively used for each colored light. SOLUTION: A white light beam set as an S polarized light beam is reflected by a total reflection mirror 3, and is made incident on the lower part of the cross dichroic prism 4 of a long narrow shape, and is converted into the light beams of three primary colors because color-separation is executed. The light beams of three primary colors are reflected upward by the total reflection mirrors 5R, 5G and 5B, and are reflected by the polarizing beam splitters 6R, 6G and 6B, and are made incident on reflection type liquid crystal panels 8R, 8G and 8B. Polarized light beams R, G and B which are reflected and outputted and carry image information are converted into a P polarized light beam from the S polarized light beam, and are transmitted through the polarizing beam splitters 6R, 6G and 6B, and are made incident on the upper part of the cross dichroic prism 4 again, and are outputted after undergoing color-synthesis.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a liquid crystal panel and a DV
More specifically, the present invention relates to a reflection type projection optical system for a projection type projector using an image generation light valve such as a digital micromirror device (D). And a reflection type projection optical system for enlarging and projecting the image.

[0002]

2. Description of the Related Art For example, as a projection type projector for displaying a color image, three primary color lights of R, G, and B are irradiated on three liquid crystal panels to carry R, G, and B image information, respectively. It is widely known that these color lights are combined and projected on a screen.

In recent years, as a liquid crystal panel, a reflection type liquid crystal panel capable of increasing an aperture ratio as compared with a transmission type liquid crystal panel and satisfying a demand for higher resolution and higher illuminance has been required. Is coming. Further, a reflection type liquid crystal projection optical system having a configuration as shown in FIG. 10 is used as a liquid crystal projector using a reflection type liquid crystal panel having such advantages as described above, which is smaller, lighter, cheaper and can eliminate convergence adjustment by a user. A device using the same is known (JP-A-3-249639).

That is, in FIG. 10, white light from a light source 201 for outputting illumination light is transmitted through a polarizing beam splitter 20 through condenser lenses 202a and 202b.
3. The polarization beam splitter 203 separates incident light into transmitted light of P component linearly polarized light (hereinafter, referred to as P polarized light) and reflected light of S component linearly polarized light (hereinafter, referred to as S polarized light). Among them, the reflected light is incident on the cross dichroic prism 204. The cross dichroic prism 204 separates incident light into R, G, and B primary color lights, and the separated R, G, and B color lights are reflection type lights corresponding to R, G, and B. Liquid crystal panels R, G, B
Are respectively modulated by image signals corresponding to the respective color lights, and at that time, are converted from S-polarized light to P-polarized light and reflected and output.

The R, G, and B color lights carrying image information, which are reflected and output from the reflective liquid crystal panels R, G, and B, respectively, enter the cross dichroic prism 204 and are combined there. The light is polarized beam splitter 20
Return to 3. Since this combined light is P-polarized light, it passes through the polarizing beam splitter 203 and is enlarged and projected on a screen by a projection lens 206 arranged on the transmitted light output side of the polarizing beam splitter 203, so that a color image is projected on the screen. Will be issued.

According to the technique described in this publication, since two processes of color separation and color synthesis are performed by one cross dichroic prism 204, the configuration of the projection optical system becomes extremely simple, The system can be made compact and the manufacturing cost can be reduced.

[0007]

However, according to the prior art described in the above publication, the polarization beam splitter
03, the polarization splitting film of the polarization beam splitter 203 needs to have a uniform polarization splitting characteristic over the entire visible light range. It is difficult to produce a polarization separation film. As a result, the amount of light that reaches the liquid crystal panels R, G, and B after being separated by the polarization beam splitter 203 differs depending on the color light, and the ratio of reaching the projection lens 206 from each of the liquid crystal panels R, G, and B also increases. Each color light will be different, and color images projected on the screen will have color unevenness.

[0008] The present invention has been made in view of the above circumstances,
In a projection optical system using a reflection type light valve, color separation of irradiation light from a light source and color synthesis of color light from a reflection type light valve are performed by one optical member, so that the size of the projection optical system is reduced and the manufacturing cost is reduced. It is an object of the present invention to provide a reflection type projection optical system capable of projecting a color image with less color unevenness on a screen while reducing the cost.

[0009]

According to a first aspect of the present invention, a reflective projection optical system includes a light source, first light reflecting means for reflecting white light from the light source, and a vertically long light reflecting means. A color light separating / synthesizing means for separating white light from the first light reflecting means incident on a lower portion thereof into light of three primary colors and outputting the light in three directions; The three second light reflecting units provided corresponding to the respective color lights, which reflect the respective color lights output from the three directions above, and the color light from the three second light reflecting units are represented by P Three polarizing beam splitters provided corresponding to each color light, which transmit by transmitting polarized light and reflect and output s-polarized light;
The polarization of the color lights output from the two polarization beam splitters is light-modulated according to a predetermined image signal, and is converted to P-polarized light and S-polarized light at the time of the modulation processing. A reflection liquid crystal panel, and the polarization of the color light reflected and output from each of the reflection liquid crystal panels is directed to the color light separation / combination unit by the three polarization beam splitters. A projection lens for combining the three colors of light incident thereon and projecting a color image based on the light combined by the color light separation / combination means on a screen is provided above the first light reflection means. Is what you do.

In this case, the color light separating / combining means is a cross dichroic prism or a Philips prism, and the first light reflecting means and the three second light reflecting means are each a reflecting prism. Preferably, each of the two polarizing beam splitters is a polarizing beam splitter prism, and these light reflecting means and these polarizing beam splitter prisms are adhered to a side wall surface of the cross dichroic prism or the Philips prism.

In this case, it is preferable that the three reflective liquid crystal panels are adhered to the upper surfaces of the corresponding polarizing beam splitter prisms and are disposed on the same plane.

Further, a reflection type projection optical system according to a second aspect of the present invention has a light source, a first light reflection means for reflecting white light from the light source, and a vertically long shape. A color light separation / combination unit that separates white light from the first light reflection unit incident on the lower part into three primary color light beams and outputs the light in three directions, and a three side direction of the color light separation / combination unit. Three second light reflecting means provided corresponding to the respective color lights, which reflect the respective color lights output from the above, and the color lights from the three second light reflecting means into respective predetermined image signals. Three digital micromirror devices provided corresponding to the respective color lights, which are optically modulated and reflected and output, the three second light reflecting means, and each of the second light reflecting means. Each of the corresponding three digital micromirror devices In the meantime, the color light from the second light reflecting means is transmitted, and only a predetermined modulated light of the color light reflected and output from the digital micromirror device is reflected toward the color light separating / combining means. And a prism for combining the three color lights from the three prisms in an upper portion of the color light separation / combination means, and further projecting a color image based on the light combined by the color light separation / combination means on a screen. A lens is provided above the first light reflecting means.

The terms "upper" and "lower" are used for convenience in representing the relative positional relationship between the members, and do not indicate the absolute positional relationship in space. .

[0014]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a reflection type projection optical system according to an embodiment of the present invention will be described with reference to the drawings.

FIG. 1 is a perspective view showing a reflection type liquid crystal projection optical system according to the first embodiment.

In FIG. 1, the white light output from the lamp 1 includes two condenser lenses 2a, 2b and a P / S
In the conversion element 2c, the light is converted into S-polarized light and enters the first total reflection mirror 3. Here, the lamp 1 is provided with a reflector for effectively utilizing light. As the lamp 1, for example, a metal halide lamp, a xenon lamp, a tungsten halogen lamp, or the like is used.

Next, the white light reflected by the first total reflection mirror 3 is incident on a lower portion of a cross dichroic prism 4 having a vertically elongated shape.

This cross dichroic prism 4
With two dichroic mirror surfaces having wavelength selectivity, the incident light is color-separated into three primary color lights of R, G, and B,
The R light is reflected to the left, the G light is transmitted forward, and the B light is reflected to the right for output.

The three primary color lights R, G, and B output from the cross dichroic prism 4 are totally reflected upward by the second total reflection mirrors 5R, 5G, and 5B corresponding to the respective color lights. Are incident on the polarization beam splitters 6R, 6G, 6B corresponding to.

The polarization beam splitters 6R, 6G, 6
Since each color light incident on B is s-polarized light, it is reflected by the polarization splitting surfaces of the polarization beam splitters 6R, 6G, and 6B, and the respective polarization beam splitters 6R, 6B.
The reflection type liquid crystal panels 8R, 8G, 8B respectively corresponding to the R, G, B color lights adhered to the side wall portions of G, 6B are respectively incident on the reflection type liquid crystal panels 8R, 8G, 8B. After being optically modulated by an image signal corresponding to light, the reflected light is output.

The reflected R, G, B polarized light carrying the image information of each color light is reflected by the reflection type liquid crystal panels 8R, 8G,
At 8B, the light is converted from S-polarized light to P-polarized light, and re-enters the polarization beam splitters 6R, 6G, and 6B in the state of P-polarized light.

Thus, the polarization beam splitter 6
The respective color lights that have entered the R, 6G, and 6B are transmitted through the polarization splitting surfaces of the polarization beam splitters 6R, 6G, and 6B, respectively, and re-enter the upper portion of the cross dichroic prism 4 described above.

Since the cross dichroic prism 4 has two dichroic mirror surfaces having wavelength selectivity as described above, the cross dichroic prism 4 reflects the R light from each of the polarization beam splitters 6R, 6G and 6B to the right, The G light is transmitted forward and the B light is reflected to the left, and the three colors of R, G, and B are combined and output.

Thereafter, the combined three-color light is supplied to the projection lens 7.
Is enlarged and projected on a screen (not shown). As a result, a color image corresponding to the image signal that has contributed to the light modulation is projected on the screen in each of the reflective liquid crystal panels 8R, 8G, and 8B.

A cold filter (not shown) is provided on the output side of the lamp 1 so that infrared rays are shielded and unnecessary temperature rise and overheating are prevented.

According to the optical system according to the first embodiment configured as described above, the color separation and the color synthesis of the three color lights of R, G, and B are performed by one cross dichroic prism 4. The number of steps for assembling the optical system can be reduced, the manufacturing cost can be reduced, and the size can be reduced.
Further, since the reflection and transmission of the polarized light of each color light is performed by using three polarizing beam splitters 6R, 6G, and 6B dedicated to each color light, the reflectance and the transmittance are different for each color light as in the above-described conventional technology. Unlike the above, no color unevenness occurs in the color image.

FIG. 2 is a perspective view showing a reflection type liquid crystal projection optical system according to a second embodiment of the present invention.

The optical system according to the second embodiment has substantially the same basic structure as that of the optical system according to the first embodiment, except that a first total reflection mirror 3 and a second total reflection mirror are provided. 5R, 5G, and 5B are a first total reflection prism 13 and a second total reflection prism 15R, 15G, and 15B, respectively. The first total reflection prism 13 and the second total reflection prism 15R are provided. , 15G, 15B and the polarizing beam splitters 16R, 16G, 16B are adhered to the cross dichroic prism 14,
This makes it possible to reduce the size of the optical system and simplify the adjustment of the position of the optical member, and eliminate the influence of air disturbance. Incidentally, it is of course possible to arrange the projection lens 17 in close contact with the cross dichroic prism 14.

Further, the white light output from the lamp 11 is supplied to two condenser lenses 12a, 12b and P /
Although the light enters the first total reflection prism 13 via the S conversion element 12c, the white light from the lamp 11 is different from the P / S conversion element 12 in the first embodiment.
At c, the light is converted into P-polarized light and enters the total reflection prism 13. As a result, each color light reflected by the second total reflection prisms 15R, 15G, and 15B passes through the polarization beam splitters 16R, 16G, and 16B.
18G and 18B are polarization beam splitters 16R and 16R, respectively.
The reflective liquid crystal panels 18R, 18G, and 18B are adhered to the upper wall surfaces of G and 16B, and are arranged in the same plane. Thereby, each reflection type liquid crystal panel 18
Adjustment of the inclination of R, 18G and 18B becomes extremely easy,
Further, it is possible to reduce the color shift in the color image projected on the screen.

The reflection type liquid crystal projection optical system described above can be modified in various other forms. For example, when it is desired to improve the resolution of each color light, the above P / P
Without disposing the S conversion elements 2c and 12c, the non-polarized light of each color is converted into each of the polarization beam splitters 6R, 6G, 6B and 16
R, 16G, and 16B, and the polarization beam splitters 6R, 6G, 6B, 16R, 16G, 1
6B, a reflective liquid crystal panel is disposed on each of the upper wall surface and one side wall surface, and each of the polarizing beam splitters 6R, 6G,
The P-polarized light and the S-polarized light separated in 6B, 16R, 16G, and 16B may be incident on the corresponding reflective liquid crystal panels, and the pixels of each of the reflective liquid crystal panels may be arranged in a pixel-shifted manner.

FIG. 3 shows a reflection type liquid crystal projection optical system according to a third embodiment of the present invention. As a color separation / combination means, a Philips prism used as a color separation prism of an image pickup system of a television camera is used. Used. 4A, 4B, and 4C show R, G, B
FIG. 5 is a top view, FIG. 6 is a bottom view, FIG. 7 is a side view, and FIG. 8 is a front view schematically. . Further, for members corresponding to the members of the first embodiment described above,
The reference numerals of the members in the first embodiment are shown by adding 20 to the reference numerals of the members.

That is, in this embodiment, the P-polarized white light from a light source (not shown) is incident on a first total reflection prism 23 having a right-angled triangular prism shape. Philips prisms (color separation / synthesis means) 24a, 24b which are reflected and form an elongated shape,
24c separates the light into three color lights of R, G, and B, and outputs the light in three directions.

The color separation of the R, G, and B light is performed in the Philips prisms 24a, 24b, and 24c in the region on the far side in FIG.

Next, the Philips prism 24a,
The R, G, and B three-color lights separated by the color lights 24b and 24c are incident on the second total reflection prisms 25R, 25G, and 25B each having a right-angled triangular prism shape, are reflected in the right-angle direction, and correspond to each other. Polarizing beam splitter 26R, 2
6G and 26B.

The polarization beam splitters 26R, 26R
Since each color light incident on G and 26B is P-polarized light, the polarization beam splitters 26R, 26G and 26B
And the polarization beam splitters 26R, 26G,
A reflective liquid crystal panel 28R bonded to the side wall surface of 26B,
The light is incident on 28G and 28B, is optically modulated by an image signal corresponding to each color light, and is reflected and output.

The R, G, and B polarized lights, which carry the reflected and output image information of each color light, are converted from P-polarized light to S-polarized light.
6G and 26B again.

Thus, the polarization beam splitter 2
6R, 26G, and 26B are reflected by the polarization splitting surfaces of the polarization beam splitters 26R, 26G, and 26B, respectively.
4 again enters the region on the near side in the drawing of FIG. R incident on the Philips prisms 24a, 24b, 24c,
The three color lights of G and B are color-combined and output by the reverse route to the above-described color separation.

Thereafter, the combined three-color light is projected onto the projection lens 2.
7, the image is enlarged and projected on a screen (not shown).

In the present embodiment, the three reflective liquid crystal panels 28R, 28G, and 28B are arranged on the same plane, and each of the reflective liquid crystal panels 28R, 28R.
It is extremely easy to adjust the inclination of G and 28B, and it is possible to prevent a color shift of a projected image.

As described above, the dichroic prisms 4 and 14 are replaced with the Philips prism 24 as color separation / combination means.
The same operation and effect as those of the above-described two embodiments can be obtained by replacing a, 24b, and 24c.

In the reflection type projection optical system of the present invention, a light valve other than a reflection type liquid crystal panel, for example, a DMD (digital micromirror device) can be used as a light valve for image formation.

When a DMD is used, the same optical member arrangement as that of each of the above embodiments can be adopted.
However, since it is not necessary to keep incident light as polarized light in the DMD, it is not necessary to dispose a polarizing beam splitter before and after the DMD. In the case of the DMD, the incident color light is converted according to an image signal. It is necessary to reflect light in two different directions, and one of them needs to be guided to the direction of the projection lens via the color separation / synthesis means. Therefore, the polarization beam splitters 6R, 6G, 6
At each position where B, 26R, 26G, and 26B were disposed, a TIR prism having an air gap is disposed.

FIG. 9 shows a fourth embodiment of the present invention.
FIG. 9 shows the operation of a reflection type projection optical system using a DMD in a G TIR prism. The operations in the R and B TIR prisms are substantially the same.

That is, the white light incident from the light source 31 is converted by the cross dichroic prism 34 into R, G,
The light is separated into three color lights B. The G color light separated here is reflected upward on the reflection surface of the first block 35G of the G TIR prism, and enters the second block 41G of the G TIR prism. The first block 35
The G light exit surface 40a and the light exit surface 40b of the second block 41G are configured to face each other via the minute air gap layer 40, and the G color light 39a reflected by the first block 35G is Since the light is incident on the light incident surface 40a at an angle substantially perpendicular to the light incident surface 40a,
Will be transmitted.

On the other hand, the G color light reflected and output by the DMD 38G is the G color light 39 when the image signal is ON.
b, and the G color light 39 when the image signal is in the OFF state.
c.

Since these color lights 39b and 39c are incident on the light incident surface 40b at a large incident angle, they are totally reflected on the light incident surface 40b, but are reflected and output from the DMD 38G. Since the directions are different depending on the ON / OFF state of the image signal, the reflection directions by the light incident surface 40b are also different from each other. Then, only the G color light 39b corresponding to the ON state of the image signal is passed through the cross dichroic prism 34 to another DM.
The color light from D is combined with the color light, and the combined light is enlarged and projected by a projection lens 37 on a screen (not shown).

In a reflection type projection optical system using a DMD, a Philips prism can be used instead of the dichroic prism.

According to the reflection type projection optical system using this DMD, it is not necessary to convert the light from the light source into polarized light, so that the number of optical parts can be reduced, and the assembling of the optical members becomes easy. The amount of light can be made more efficient.

It is of course possible to add a well-known configuration such as insertion of an integrator using a fly-eye lens or the like for the purpose of preventing light quantity unevenness at the subsequent stage of the lamp.

[0050]

As described above, according to the reflection type projection optical system of the present invention, the color light separation and the synthesis of the color light are performed by one color light separation / combination means, so that the number of assembling steps of the optical system can be reduced. Further, the manufacturing cost can be reduced and the optical system can be made compact.

Furthermore, in the case of using a liquid crystal panel, the reflection and transmission of the polarized light of each color light is performed by using three polarizing beam splitters dedicated to each color light. Also, the transmittance is different for each color light, and no color unevenness occurs in the generated image.

Further, since a polarizing beam splitter is not required in the apparatus using the DMD, color unevenness of a generated image based on the polarization splitting characteristic of the polarizing beam splitter does not occur.

[Brief description of the drawings]

FIG. 1 is a schematic plan view showing a reflective liquid crystal projection optical system according to a first embodiment of the present invention.

FIG. 2 is a schematic plan view showing a reflective liquid crystal projection optical system according to a second embodiment of the present invention.

FIG. 3 is a schematic plan view showing a reflective liquid crystal projection optical system according to a third embodiment of the present invention.

FIG. 4 is an optical path diagram for each color light of a reflective liquid crystal projection optical system according to a third embodiment of the present invention.

FIG. 5 is a top view of a reflective liquid crystal projection optical system according to a third embodiment of the present invention.

FIG. 6 is a bottom view of a reflective liquid crystal projection optical system according to a third embodiment of the present invention.

FIG. 7 is a side view of a reflective liquid crystal projection optical system according to a third embodiment of the present invention.

FIG. 8 is a front view of a reflective liquid crystal projection optical system according to a third embodiment of the present invention.

FIG. 9 is a diagram showing an operation of a reflection type projection optical system using a DMD according to a fourth embodiment of the present invention in a G TIR prism.

FIG. 10 is a schematic plan view showing a reflective liquid crystal projection optical system according to the related art.

[Explanation of symbols]

1, 11 Lamp 2a, 2b, 12a, 12b Condenser lens 2c, 12c P / S conversion element 3 First total reflection mirror 4, 14, 34 Cross dichroic prism 5R, 5G, 5B Second total reflection mirror 6R, 6G , 6B, 16R, 16G, 16B, 26R, 26G, 26B Polarizing beam splitters 7, 17, 27, 37 Projection lenses 8R, 8G, 8B, 18R, 18G, 18B, 28R,
28G, 28B Reflective liquid crystal panel 13, 23 First total reflection prism 15R, 15G, 15B, 25R, 25G, 25B
Second total reflection prism 24a, 24b, 24c Phillips prism 31 Light source First of 35G TIR prism
Block 38G DMD 39a, 39b, 39c Color light of G 40 Air gap layer 40a Light incidence surface 40b Light emission surface 41G Second of TIR prism
block

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 2H088 EA14 EA15 EA16 EA18 HA13 HA20 HA23 HA24 HA28 MA04 MA16 MA20 2H091 FA05X FA05Z FA10X FA10Z FA14Z FA26X FA26Z FA41Z LA11 LA18 MA07 2H099 AA11 AA12 BA09 CA01

Claims (4)

[Claims] 1. A light source, a first light reflecting means for reflecting white light from the light source, and a vertically long shape, and a white light from the first light reflecting means incident on a lower portion thereof A color light separation / combination means for separating light into three primary color light beams and outputting the light in three directions; and a color light separation / combination means for reflecting each color light output from the three side directions of the color light separation / combination means upward. Corresponding to each color light, which outputs by transmitting P-polarized light and reflecting S-polarized light from the three second light reflecting means provided by The three polarization beam splitters provided, and the polarizations of the color lights output from the three polarization beam splitters are respectively light-modulated in accordance with a predetermined image signal, and P-polarized light and S-polarized light are converted during the modulation processing. Reflection provided for each color light to be reflected and output And a polarization panel. A reflection lens for combining the three color lights and projecting a color image based on the light combined by the color light separation / combination means on a screen above the first light reflection means; Projection optics. 2. The color light separation / combination means is a cross dichroic prism or a Philips prism, the first light reflection means and the three second light reflection means are each reflection prisms, and the three polarization beam splitters. 2. A reflection type projection system according to claim 1, wherein each of said prisms is a polarizing beam splitter prism, and said light reflecting means and said polarizing beam splitter prism are bonded to a side wall surface of said cross dichroic prism or Philips prism. Optical system. 3. The polarizing liquid crystal panel according to claim 2, wherein the three reflective liquid crystal panels are adhered to upper surfaces of the corresponding polarizing beam splitter prisms and are disposed in the same plane.
The reflective projection optical system according to claim 1. 4. A light source, a first light reflecting means for reflecting white light from the light source, and a vertically long shape, and a white light from the first light reflecting means incident on a lower portion thereof. A color light separation / combination means for separating light into three primary color light beams and outputting the light in three directions; and a color light separation / combination means for reflecting each color light output from the three side directions of the color light separation / combination means upward. Three second light reflecting means provided in a predetermined manner, and respectively modulating the color lights from the three second light reflecting means in accordance with a predetermined image signal and reflecting and outputting the modulated light. Between each of the three digital micromirror devices, the three second light reflecting means, and the three digital micromirror devices corresponding to each of the second light reflecting means. Transmitting the color light from the second light reflecting means; And three prisms for reflecting only predetermined modulated light out of the color light reflected and output from the micro-mirror device toward the color light separation / combination means, wherein the three color lights from the three prisms are subjected to the color light separation. A projection lens for combining the light in the upper part of the combining means and projecting a color image based on the light combined by the color light separating / combining means on a screen is provided above the first light reflecting means. Reflection type projection optical system.