JPH11258567A - Liquid crystal projector - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent the decrease in contrast of a projected display. SOLUTION: A reflection type blue-translucent filter 23 is arranged between a liquid crystal panel 19 for blue and a cross dichroic prism 21. A quarter-wave plate 24 on the incident side is arranged between the liquid crystal panel 19 and a reflection type blue-translucent filter 23. A quarter-wave plate 25 on the exiting side is arranged between the reflection type blue-translucent filter 23 and the cross dichroic prism 21. The quarter-wave plate 24 on the incident side is arranged so that the lagging axis forms a tilt angle of 45 degrees with the polarized direction of the light outgoing from the liquid crystal panel 19. The quarter-wave plate 24 on the incident side and the quarter-wave plate 25 on the exiting side are arranged so that their lagging axes are orthogonal to each other. It is possible to prevent the decrease in contrast of the liquid crystal panel 19 by arranging green light eliminating means 23, 25 between the liquid crystal panel 19 and a color synthesis system.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a liquid crystal projector, and more particularly, to a liquid crystal projector using three liquid crystal panels.

[0002]

2. Description of the Related Art FIG. 3 shows a conventional liquid crystal projector. A conventional liquid crystal projector device includes a light source 101, a curved reflecting mirror 102, a UV / I
R (ultraviolet / infrared) cut filter 103, red-reflecting color separating dichroic mirror 104, green-reflecting color separating dichroic mirror 105, reflecting mirror 106,
107, 108; relay lenses 109, 110; condenser lenses 111, 112, 113;
4, 115, 116, a liquid crystal panel 117 for red, a liquid crystal panel 118 for green, a liquid crystal panel 119 for blue, a red filter 120, and a cross dichroic prism 121.
And a projection lens 122.

[0003]

However, in the conventional liquid crystal projector, a green liquid crystal panel 118 is used.
4 has a certain spread as shown in FIG. 4, and the cross dichroic prism 121 shifts to a short wavelength side for light having a large incident angle due to the incident angle dependence as shown in FIG. Since light having a small incident angle shifts to a longer wavelength side, light having a large incident angle to the red reflective film is reflected by the red reflective film. Therefore, in the conventional liquid crystal projector, the green light emitted from the green liquid crystal panel 118 is reflected by the red reflecting surface of the cross dichroic prism 121 and is incident from the back surface of the blue liquid crystal panel 119, so that the blue liquid crystal panel 119 is formed. The first problem is that the contrast of the image is reduced.

Further, in the conventional liquid crystal projector, if an absorption type blue transmission filter is arranged in order to prevent the green light from entering the back side of the liquid crystal panel 119 for blue, the absorption type blue transmission filter has a low transmittance at present. There is a second problem that the white balance is deteriorated because there is nothing.

In the conventional liquid crystal projector, if a reflection type blue transmission filter is arranged in order to prevent green light from entering the back surface of the blue liquid crystal panel 119, the green light reflected by the reflection type blue transmission filter is cross-dichroic. The green reflecting liquid crystal panel 11 reflects the red reflecting surface of the prism 121.
8, there is a third problem that the contrast of the green liquid crystal panel 118 deteriorates.

[0006] A first object of the present invention is to provide a liquid crystal projector device in which the contrast of a projection screen does not decrease.

A second object of the present invention is to provide a liquid crystal projector having an excellent white balance without reducing the amount of blue light.

[0008]

According to a first aspect of the present invention, a light from a light source is incident on a color separation system comprising a plurality of dichroic mirrors and a reflection mirror. An optical image is formed by a red liquid crystal panel, a green liquid crystal panel, and a blue liquid crystal panel that receive the separated light by separating the light into three primary colors of red, green, and blue, and the formed optical image is formed into two colors. In a liquid crystal projector device in which a combining surface is combined with a color combining system arranged orthogonally and a combined optical image is projected on a screen by a projection lens, green light is removed between the liquid crystal panel for blue and the color combining system. A green light removing means is provided.

According to a second aspect of the present invention, in the first aspect of the invention, the green light removing means includes a reflective blue transmission filter disposed between the blue liquid crystal panel and the color synthesizing system; A 1/4 wavelength plate disposed between the reflective blue transmission filter and the 1/4 wavelength plate, wherein the direction of the slow axis is different from the polarization direction of light emitted from the blue liquid crystal panel. It is characterized by.

According to a third aspect of the present invention, in the second aspect of the invention, the direction of the slow axis of the quarter-wave plate is inclined 45 degrees with respect to the polarization direction of the light emitted from the blue liquid crystal panel. It is characterized by being arranged as follows.

According to a fourth aspect of the present invention, in the first aspect of the invention, the green light removing means includes a reflective blue transmission filter disposed between the blue liquid crystal panel and the color combining system, and a blue liquid crystal panel. 1 disposed between the reflective blue transmission filter
The １ ／ wavelength plate is characterized in that the direction of the slow axis is different from the polarization direction of the light emitted from the blue liquid crystal panel.

According to a fifth aspect of the present invention, in the fourth aspect of the present invention, the direction of the slow axis of the quarter-wave plate is inclined 45 degrees with respect to the polarization direction of the light emitted from the blue liquid crystal panel. It is characterized by being arranged as follows.

According to a sixth aspect of the present invention, in the first aspect of the present invention, the green light removing means includes a reflective blue transmission filter disposed between the blue liquid crystal panel and the color synthesizing system; A first one disposed between the reflective blue transmission filter and the first type;
A first quarter wavelength plate, and a second quarter wavelength plate between the blue liquid crystal panel and the reflective blue transmission filter.
The direction of the slow axis of the four-wave plate and the direction of the slow axis of the second quarter-wave plate are different from each other, and are different from the polarization direction of light emitted from the blue liquid crystal panel.

According to a seventh aspect of the present invention, in the sixth aspect of the present invention, the direction of the slow axis of the first quarter-wave plate is inclined by 45 degrees with respect to the polarization direction of the light emitted from the blue liquid crystal panel. And the first quarter-wave plate and the second quarter-wave plate are arranged such that their slow axes are orthogonal to each other.

[0015]

Next, embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1 is a schematic diagram showing a liquid crystal projector device as one embodiment of the present invention. As shown in FIG. 1, a liquid crystal projector device as one embodiment of the present invention includes a light source 1, a curved reflecting mirror 2, a UV / IR cut filter 3, a red-reflecting color separation dichroic mirror 4, A green reflection color separation dichroic mirror 5, reflection mirrors 6, 7, 8, relay lenses 9, 10, condenser lenses 11, 12, 13,
Polarizing plates 14, 15, 16, liquid crystal panel 17 for red, liquid crystal panel 18 for green, liquid crystal panel 19 for blue, red filter 20, cross dichroic prism 21, projection lens 22, reflection type blue transmission It has a filter 23, a quarter-wave plate 24 on the incident side, and a quarter-wave plate 25 on the emission side.

The white light beam emitted from the light source 1 is reflected by the curved reflecting mirror 2 and emitted as a substantially parallel light beam. This parallel light beam is a red-reflected color separation dichroic mirror 4
The light is separated into red light, green light, and blue light by the color separation dichroic mirror 5 that reflects green light and green light. The red light is incident on the red liquid crystal panel 17 via the reflection mirror 6, the condenser lens 11, and the polarizing plate 14. The green light passes through the condenser lens 12 and the polarizing plate 15 and passes through the green liquid crystal panel 18.
Incident on. The blue light is a relay lens 9, a reflection mirror 7, a relay lens 10, a reflection mirror 8, and a condenser lens 1.
Then, the light enters the blue liquid crystal panel 19 through the polarizing plate 16.

Image information corresponding to red light is input to the red liquid crystal panel 17, and a red optical image is formed by modulation. Image information corresponding to green light is input to the green liquid crystal panel 18, and a green optical image is formed by modulation. Image information corresponding to blue light is input to the blue liquid crystal panel 19, and a blue optical image is formed by modulation. These red liquid crystal panel 17 and green liquid crystal panel 18
And the optical image from the blue liquid crystal panel 19 are synthesized by the cross dichroic prism 21 and given to the projection lens 22. The projection lens 22 magnifies the synthesized optical image and projects it on a screen.

The reflection type blue transmission filter 23 is disposed between the blue liquid crystal panel 19 and the cross dichroic prism 21. The 側 wavelength plate 24 on the incident side is arranged between the blue liquid crystal panel 19 and the reflective blue transmission filter 23. The 側 wavelength plate 25 on the emission side is disposed between the reflective blue transmission filter 23 and the cross dichroic prism 21. The 側 wavelength plate 24 on the incident side is
It is arranged such that the direction of the slow axis is inclined 45 degrees with respect to the polarization direction of the light emitted from the blue liquid crystal panel 19. Incident quarter-wave plate 24 and emission quarter-wave plate 25
Are arranged such that the slow axes are orthogonal to each other. Thereby, the polarized light emitted from the blue liquid crystal panel 19 is stored as it is, so that a polarizing screen can be used, and a high-contrast image can be provided even in a bright room.

The green light removing means disposed between the blue liquid crystal panel 19 and the cross dichroic prism 21 which is a color combining system for removing green light is not limited to these embodiments. For example, the green light removing means is a reflective blue transmission filter 23 disposed between the blue liquid crystal panel 19 and the cross dichroic prism 21.
And an output quarter-wave plate 25 disposed between the cross dichroic prism 21 and the reflective blue transmission filter 23. The output quarter-wave plate 25 has a slow axis direction. The polarization direction of the light emitted from the blue liquid crystal panel 19 may be different.

The green light removing means includes a reflection type blue transmission filter 23 disposed between the blue liquid crystal panel 19 and the cross dichroic prism 21 and a reflection type blue transmission filter 23 disposed between the cross dichroic prism 21 and the reflection type blue transmission filter 23. And the output side quarter-wave plate 25 is arranged at an angle of 45 degrees with respect to the polarization direction of the light emitted from the blue liquid crystal panel 19. May be arranged in the same direction.

The green light removing means includes a reflection type blue transmission filter 23 disposed between the blue liquid crystal panel 19 and the cross dichroic prism 21, and the blue liquid crystal panel 1.
And a reflection type blue transmission filter 23, and a quarter-wave plate 24 on the incident side which is disposed between the reflection type blue transmission filter 23 and the liquid crystal panel 19 for the blue phase. May be arranged differently with respect to the polarization direction of the emitted light.

Further, the green light removing means includes a reflection type blue transmission filter 23 disposed between the blue liquid crystal panel 19 and the cross dichroic prism 21 and a reflection type blue transmission filter 23 disposed between the blue liquid crystal panel 19 and the reflection type blue transmission filter 23. And a quarter-wave plate 24 on the incident side interposed therebetween.
The wave plate 24 may be arranged so that the direction of the slow axis is inclined 45 degrees with respect to the polarization direction of the light emitted from the blue liquid crystal panel 19.

By arranging the green light removing means, green light does not enter from the back surface of the blue liquid crystal panel 19,
A decrease in the contrast of the blue liquid crystal panel 19 can be prevented.

Further, since the reflection type blue transmission filter 23 is provided as the green light removing means, the decrease in blue light is small, and the change in white balance is small.

Further, since the 波長 wavelength plate 25 on the emission side is disposed between the reflection type blue transmission filter 23 and the cross dichroic prism 21, the green light reflected by the reflection type blue transmission filter 23 is used for green. Since there is no return to the liquid crystal panel 18, a decrease in the contrast of the green liquid crystal panel 18 can be prevented.

The 側 wavelength plate 24 on the incident side is disposed so that the direction of the slow axis is inclined 45 degrees with respect to the polarization direction of the light emitted from the blue liquid crystal panel 19. /
Since the four-wavelength plate 24 and the quarter-wave plate 25 on the emission side are arranged so that the slow axes are orthogonal to each other, the polarized light emitted from the blue liquid crystal panel 19 is preserved as it is, so that the polarizing screen is It can be used and can provide high-contrast images even in bright rooms.

[0027]

According to the first aspect of the invention, since the green light removing means for removing green light is provided between the blue liquid crystal panel and the color synthesizing system, the contrast of the blue liquid crystal panel is reduced. Can be prevented.

According to the present invention, since the reflection type blue transmission filter having high transmittance of blue light is provided as the green light removing means, the reduction of blue light can be reduced and the change of white balance can be reduced. it can.

According to the second, third, sixth and seventh aspects of the present invention, the １ ／ wavelength plate is disposed on the emission side of the reflection type blue transmission filter, so that the green light reflected by the reflection type blue transmission filter is reduced. Since the polarization direction is rotated and easily absorbed by the polarizing plate on the emission side of the green liquid crystal panel, a decrease in the contrast of the green liquid crystal panel can be prevented even if a reflective blue transmission filter is used.

[Brief description of the drawings]

FIG. 1 is a schematic diagram showing a liquid crystal projector device as one embodiment of the present invention.

FIG. 2 is a plan view for explaining a slow axis direction of a 波長 wavelength plate of the liquid crystal projector device of the present invention.

FIG. 3 is a schematic diagram showing a conventional liquid crystal projector device.

FIG. 4 is a diagram for explaining an angle of incidence on a cross dichroic prism.

FIG. 5 is a diagram for explaining the incident angle dependence of a cross dichroic prism.

[Explanation of symbols]

 Reference Signs List 1 light source 2 curved reflecting mirror 3 UV / IR (ultraviolet / infrared) cut filter 4, 5 color separation dichroic mirror 6, 7, 8 reflecting mirror 9, 10 relay lens 11, 12, 13 condenser lens 14, 15, 16 polarizing plate Reference Signs List 17 liquid crystal panel for red 18 liquid crystal panel for green 19 liquid crystal panel for blue 20 red filter 21 cross dichroic prism 22 projection lens 23 reflective blue transmission filter 24 quarter-wave plate on incident side 25 quarter-wave plate on emission side

Claims (7)

[Claims] 1. A light from a light source is incident on a color separation system comprising a plurality of dichroic mirrors and a reflection mirror, and is separated into light of three primary colors of red, green and blue. An optical image is formed by the receiving red, green and blue liquid crystal panels, and the formed optical image is synthesized by a color synthesizing system in which two color synthesizing planes are arranged orthogonally. A liquid crystal projector device for projecting an optical image on a screen by a projection lens, wherein a green light removing unit for removing green light is arranged between the blue liquid crystal panel and the color synthesizing system. . 2. The liquid crystal projector device according to claim 1, wherein said green light removing means includes: a reflective blue transmission filter disposed between said blue liquid crystal panel and said color synthesizing system; And a quarter-wave plate disposed between the system and the reflection type blue transmission filter, and the direction of the slow axis of the quarter-wave plate is set to the polarization direction of light emitted from the blue liquid crystal panel. A liquid crystal projector device which is different from the above. 3. The liquid crystal projector device according to claim 2, wherein the quarter-wave plate has a direction in which the direction of the slow axis is inclined by 45 degrees with respect to the polarization direction of light emitted from the blue liquid crystal panel. A liquid crystal projector device, wherein the liquid crystal projector device is arranged in such a manner as to be arranged as follows. 4. The liquid crystal projector device according to claim 1, wherein the green light removing unit includes a reflective blue transmission filter disposed between the blue liquid crystal panel and the color combining system, and the blue liquid crystal. A 1/4 wavelength plate disposed between the panel and the reflective blue transmission filter;
The four-wavelength plate is characterized in that the direction of the slow axis is different from the direction of polarization of light emitted from the blue liquid crystal panel. 5. The liquid crystal projector device according to claim 4, wherein the quarter-wave plate has a direction in which the direction of the slow axis is inclined by 45 degrees with respect to a polarization direction of light emitted from the blue liquid crystal panel. A liquid crystal projector device, wherein the liquid crystal projector device is arranged in such a manner as to be arranged as follows. 6. The liquid crystal projector device according to claim 1, wherein said green light removing means includes a reflective blue transmission filter disposed between said blue liquid crystal panel and said color synthesizing system, and said color synthesizing system. A first quarter-wave plate disposed between the blue liquid crystal panel and the reflective blue transmission filter; and a second quarter-wave plate disposed between the blue liquid crystal panel and the reflective blue transmission filter. The first 波長 wavelength plate and the second ４ wavelength plate have different slow axis directions and different directions of polarization of light emitted from the blue liquid crystal panel. A liquid crystal projector device characterized by the above-mentioned. 7. The liquid crystal projector device according to claim 6, wherein the direction of the slow axis of the first quarter-wave plate is inclined by 45 degrees with respect to the polarization direction of the light emitted from the blue liquid crystal panel. Wherein the first quarter-wave plate and the second quarter-wave plate are arranged such that their slow axes are orthogonal to each other.