JPH09179092A - Image display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make an image display whose luminance balance is kept by reducing the difference in distance (optical path) from a light source between two color liquid crystal panels as much as possible. SOLUTION: This device splits light, projected by the light source 1 and made incident on a polarization beam splitter 5, into P-polarized light and S-polarized light; and the P-polaized light is guided to a 1st color liquid crystal panel (consisting of a hologram color filter 7 and a liquid crystal panel 8) and the S-polarized light is guided to a 2nd color liquid crystal panel (consisting of a hologram color filter 8 and a liquid crystal panel 10), so that the video lights are displayed on a screen 13 through projection lenses 11 and 12 respectively. In this case, both the polarized lights are projected from the polarization beam splitter 5 so as to approach the plane containing the diffraction surfaces of the hologram color filters 7 and 8 and while the P-polarized light is guided to the 1st color liquid crystal panel 5, the S-polarized light is guided to the 2nd color liquid crystal panel.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image display device, and more particularly to an image display device which uses two color liquid crystal panels to superimpose respective images on a screen and project the images.

[0002]

2. Description of the Related Art As an image display device using one light source, an image display device of a one-lamp type light source separation optical system using a polarization beam splitter (PBS) has been proposed (for example, Japanese Patent Application No. 6-207025). reference).

The color liquid crystal panel used in the above-mentioned image display device generally has pixel portions arranged in a matrix and R (red), G (green), and B facing the pixel portions.
It is composed of a color filter composed of (blue) cells.

However, the separation of the three primary colors by the color filter consisting of R, G, and B cells has a utilization efficiency of 1/3 of the light source light because each color cell absorbs light in other wavelength bands. When the amount of light is increased, there is a problem of heat resistance, and it is difficult to achieve high brightness.

Therefore, a hologram color filter (H that separates the three primary colors by utilizing the converging effect of each wavelength of the hologram and the difference in the diffraction angle without using the R, G, B cells.
CF) has been proposed (see JP-A-6-308332: G02B 5/32).

The hologram color filter described above includes a counter substrate 41 and a polarizing plate 42 as shown in FIG.
And the hologram color filter 40 is disposed between the two, and the three primary colors are separated and diffracted and focused on each pixel portion of the liquid crystal layer 43 by utilizing the light collection effect by each wavelength of the hologram color filter 40 and the difference in diffraction angle. It is a thing.

Further, the hologram color filter described above is advantageous in that it has high utilization efficiency because it diffracts and collects the light from the light source to the pixel portion, and has little heat absorption in the hologram color filter, so that it has excellent heat resistance. .

Here, as a concrete configuration of the image display device using the hologram color filter,
The configuration shown in FIG. 4 can be considered.

The image display device shown in FIG. 4 has a first structure including a hologram color filter 7 and a liquid crystal panel 9.
Color liquid crystal panel and a second color liquid crystal panel composed of a hologram color filter 8 and a liquid crystal panel 10, and the light emitted from the light source 1 having the reflector 2 is made incident on the polarization beam splitter 5 to obtain the polarized beam. The P-polarized light transmitted through the splitter 5 is separated into the S-polarized light reflected by the polarization beam splitter 5, the P-polarized light is guided to the first color liquid crystal panel, and the S-polarized light is transmitted to the second color liquid crystal panel. Image light obtained through each color liquid crystal panel to the projection lens 1
An image is displayed by superimposing it on the screen 13 via 1 and 12.

[0010]

However, in the image display device shown in FIG. 4, the P-polarized light transmitted through the polarization beam splitter 5 is separated by a predetermined distance (liquid crystal panel) from both hologram color filters 7. The hologram color filter 7 is reflected by the reflection mirror 22 after traveling (distance corresponding to the arrangement interval of 9 and 10).
To reach. Therefore, advancing a predetermined distance in the away direction increases the distance to reach the hologram color filter 7, and the optical path difference between both polarized lights becomes a distance corresponding to the arrangement interval of the liquid crystal panels 9 and 10. The distance is the sum of the increased distances.

The brightness of the light when it reaches the liquid crystal panels 9 and 10 is inversely proportional to the square of the optical path length from the light source 1 to each color liquid crystal panel, so that there is a large difference in the optical paths of both polarized lights as described above. Therefore, the brightness balance of the light reaching the liquid crystal panels 9 and 10 becomes different,
There is a drawback that the brightness of the images obtained by both liquid crystal panels 9 and 10 becomes non-uniform.

The present invention has been made in view of the above circumstances, and the difference in the distances (optical paths) from the light source to the two color liquid crystal panels is reduced as much as possible, and the image display in which the luminance is balanced is obtained. It is an object of the present invention to provide an image display device capable of performing the above.

[0013]

The image display device of the present invention is provided with two color liquid crystal panels for performing color spectroscopy with a hologram color filter, and makes light emitted from one light source enter a polarization beam splitter. To separate the polarized light transmitted through the polarized beam splitter and the polarized light reflected by the polarized beam splitter, and guide one polarized light to one color liquid crystal panel and the other polarized light to the other color liquid crystal panel. In the image display device configured to perform image display by superimposing the image light obtained through each color liquid crystal panel on the screen via the projection lens, both of the polarized lights are generated by the hologram color filter. The polarized beam is emitted from the polarization beam splitter in a direction approaching the plane including the diffractive surface, and one polarized light is It led to one of the color liquid crystal panel through the mirror, wherein the other of the polarized light is made to be directly guided to the other of the color liquid crystal panel.

According to the above arrangement, both the polarized light transmitted through the polarized beam splitter and the reflected polarized light travel in the direction approaching the surface including the diffraction surface of the hologram color filter. That is, it is necessary to reduce the distance to reach the color liquid crystal panel by advancing a predetermined distance (a distance corresponding to the arrangement interval of the color liquid crystal panels) until one polarized light passing through the polarization beam splitter reaches the reflection mirror. Therefore, the difference in the distances (optical paths) from the light source to the two color liquid crystal panels can be minimized, and an image display with a well-balanced luminance can be performed.

The optical path for guiding the one polarized light to the one color liquid crystal panel and the longer optical path for guiding the other polarized light to the other color liquid crystal panel are substantially the optical paths of the optical path. You may have the transparent plate which has a predetermined refractive index and a predetermined thickness for shortening length and making both optical path lengths substantially equal.

According to this, since both optical path lengths are made substantially equal to each other, it is possible to display an image with good optical balance in both color liquid crystal panels.

Further, the image display device of the present invention is provided with two color liquid crystal panels for performing color spectroscopy with a hologram color filter, and the light emitted from one light source is made incident on the polarization beam splitter. The first polarized light transmitted through the splitter and the second polarized light reflected by the polarized beam splitter are separated, and the first polarized light is passed through the first reflection mirror to the first color liquid crystal panel. The second polarized light is guided to the second color liquid crystal panel via the second reflection mirror, and the image light obtained through the first and second color liquid crystal panels is combined by the polarization beam splitter to project the projection lens. In an image display device in which an image is displayed by superimposing it on a screen via a screen, the first polarized light transmitted through the polarization beam splitter is the first reflection mirror. And the distance to the first color liquid crystal panel via the second reflection mirror and the second polarized light reflected by the polarization beam splitter to the second color liquid crystal panel via the second reflection mirror. Is set to be substantially equal to the distance.

The optical path length of the first polarized light that has passed through the polarization beam splitter is the distance that the polarized light reaches the first color liquid crystal panel via the first reflecting mirror. The optical path length of the second polarized light reflected by the polarizing beam splitter is the distance that the polarized light reaches the second color liquid crystal panel via the second reflecting mirror. Since both distances are set to be substantially equal to each other as described above, the optical path length of the first polarized light and the optical path length of the second polarized light are substantially equal to each other, the optical path difference is eliminated, and the brightness balance is maintained. An image can be displayed.

[0019]

BEST MODE FOR CARRYING OUT THE INVENTION

(Embodiment 1) An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a layout diagram of optical components of an image display device to which the present invention is applied in a 2-lens 1-PBS system.

Light emitted from the light source 1 having the reflector 2 is separated into S-polarized light and P-polarized light by passing through the polarization beam splitter 5. That is, the P-polarized light is directly transmitted through the polarization beam splitter 5, and the S-polarized light is reflected by the polarization beam splitter 5. Then, the both polarized lights become parallel lights having a small light dispersion angle at the collimator lenses 3 and 4, respectively, and the P polarized light is guided to the hologram color filter 7 at a predetermined incident angle by being reflected by the reflection mirror 6. , S-polarized light is directly guided to the hologram color filter 8 at a predetermined incident angle.

The P-polarized light reflected by the reflection mirror 6 is incident on the first color liquid crystal panel composed of the hologram color filter 7 and the liquid crystal panel 9, and the first color liquid crystal panel is formed. One of the image lights is generated by passing through the projection lens 11 and is projected on the screen via the projection lens 11. Further, the S-polarized light is directly incident on the second color liquid crystal panel composed of the hologram color filter 8 and the liquid crystal panel 10.
The other image light is generated by passing through the second color liquid crystal panel and is projected on the screen through the projection lens 12.

Here, the light source 1 emits light toward a surface including both diffraction surfaces of the hologram color filters 7 and 8 (hereinafter, simply referred to as a surface including a diffraction surface). More specifically, the incident angle of the light from the light source 1 with respect to the surface including the diffractive surface is set to 50 °. The S-polarized light reflection surface of the polarization beam splitter 5 and the reflection surface of the reflection mirror 6 arranged on the emission optical path of the light source 1 are shown in the drawing with respect to a surface perpendicular to the surface including the diffraction surface. It is tilted 5 ° counterclockwise.

Therefore, both the P-polarized light and the S-polarized light are emitted from the polarization beam splitter 5 in a direction approaching the plane including the diffraction surface, and at the S-polarized light reflection surface of the polarization beam splitter 5. The reflected S-polarized light is incident on the diffractive surface of the hologram color filter 8 at an incident angle of 40 °, and the P-polarized light transmitted through the polarization beam splitter 5 is reflected by the reflection mirror 6 to be reflected by the hologram color filter 7 Angle of incidence on the diffractive surface of 40
It will be incident at °.

With the above arrangement, both the P-polarized light transmitted through the polarization beam splitter 5 and the reflected S-polarized light travel in the direction approaching the plane including the diffraction surface of the hologram color filters 7, 8. That is, it is necessary to advance a predetermined distance (a distance corresponding to the arrangement interval of the color liquid crystal panels) for the P-polarized light passing through the polarization beam splitter 5 to reach the reflection mirror 6 by the distance to reach the first color liquid crystal panel. Since it contributes to the reduction, the difference between the distances (optical paths) from the light source 1 to the two color liquid crystal panels is reduced as much as possible, and it is possible to display an image with a well-balanced luminance.

The optical path difference in this embodiment will be specifically described. For example, the distance from the polarization beam splitter 5 to the hologram color filter 8 is about 100 m.
m, the distance from the polarization beam splitter 5 to the reflection mirror 6 is about 76 mm, the distance from the reflection mirror 6 to the hologram 7 is about 35 mm, and one optical path length is 100 mm.
mm, the other optical path length is 111 mm, so the optical path difference is 1
1 mm. In this embodiment, the incident angle of the polarized light on the hologram color filters 7 and 8 is 40 °.
Therefore, the optical path difference cannot be set to 0,
When the incident angle of the polarized light is 45 °, it is possible to eliminate the optical path difference at all.

Further, in this embodiment, the reflecting mirror 6
Is disposed in the vicinity of the hologram color filter 7, the optical path length itself is also shortened, and a decrease in brightness is prevented.

When the above image display device is used as a three-dimensional image display device, for example, the liquid crystal panel 10 is used.
The image for the right eye is displayed on the screen, the image for the left eye is displayed on the liquid crystal panel 9, and the images are projected on the screen 13 by the projection lenses 11 and 12. Screen 1
Since the image for the left eye on 3 is P-polarized light and the image for the right eye is S-polarized light, the left eye has a polarizing plate that absorbs S-polarized light and transmits P-polarized light. Transmits S-polarized light,
By wearing polarizing glasses having polarizing plates that absorb P-polarized light, images corresponding to the left and right eyes can be observed, and good color stereoscopic images can be obtained. Of course, the present invention can be applied to other three-dimensional image display, such as a method using a lenticular plate.

On the other hand, the above-mentioned image display device can be used as a two-dimensional image display device. For example, of two fields constituting one frame, an odd side field is displayed on one color liquid crystal panel and an even side field is displayed. It is possible to display on the other color liquid crystal panel. In this case, when a color liquid crystal panel having a stripe arrangement is used, the position of the R pixel portion of one color liquid crystal panel is the position of the R pixel portion of the other color liquid crystal panel in the superimposed image on the screen 13. The horizontal resolution can be improved by shifting the distance by 1.5 pixels. When a color liquid crystal panel having a delta arrangement is used, if the pixel arrangement relationship between one color liquid crystal panel and the other color liquid crystal panel is shifted by one pixel in the superimposed image on the screen 13. The horizontal resolution can be improved.

(Second Embodiment) Next, another embodiment of the present invention will be described with reference to FIG.

As shown in FIG. 2, the image display device of this embodiment has the same optical component arrangement as that of the image display device of the first embodiment. This is different from the image display device according to the first embodiment described above in that a glass plate 24 is arranged between the collimator lens 4 and the reflection mirror 6 arranged on the optical path of the polarized light. In the optical system having the optical path difference (11 mm) specifically shown in the first embodiment, the glass plate 24 has, for example, a refractive index of about 1.5 and a thickness of about 33.
The thing of mm is used.

In the first embodiment, the optical path length of the P-polarized light transmitted through the polarization beam splitter 5 is 11 mm longer than the optical path length of the S-polarized light. By arranging the glass plate 24, the substantial optical path length of the P-polarized light is shortened and becomes equal to the optical path length of the S-polarized light. In this way, by making both optical path lengths substantially equal to each other, it is possible to display an image with good optical balance (color balance, color purity) on both color liquid crystal panels.

(Third Embodiment) Next, another embodiment of the present invention will be described with reference to FIG.

FIG. 3 is a layout diagram of optical parts of an image display device to which the present invention is applied in the one projection lens and two PBS system.

Light emitted from the light source 1 having the reflector 2 is separated into S-polarized light and P-polarized light by passing through the polarization beam splitter 5. That is, the P-polarized light is directly transmitted through the polarization beam splitter 5, and the S-polarized light is reflected by the polarization beam splitter 5. The P-polarized light that has passed through the polarization beam splitter 5 travels parallel to the polarization plane of the hologram color filter 17, which will be described later, and
The S-polarized light reflected by the polarization beam splitter 5 travels parallel to the polarization plane of the hologram color filter 16 described later.

Then, both polarized lights are collimated by the collimator lenses 3 and 4 into parallel lights having a small light dispersion angle, and P
The polarized light is reflected by the reflection mirror 15 to be guided to the hologram color filter 17 at a predetermined incident angle, and the S-polarized light is reflected to the reflection mirror 14 to be guided to the hologram color filter 16 at a predetermined incident angle. It is like this. The reflection mirror 15 is arranged such that the angle formed by the surface perpendicular to the reflection surface and the incident direction of the P-polarized light is 25 °, and the reflection mirror 14
Are arranged such that the angle formed by the plane perpendicular to the reflecting surface and the incident direction of the S-polarized light is 25 °, so that the incident angle of each polarized light on the hologram color filters 16 and 17 is 40 °. It becomes °.

As described above, the P-polarized light reflected by the reflection mirror 15 is incident on the first color liquid crystal panel composed of the hologram color filter 17 and the liquid crystal panel 18, and the first color liquid crystal panel 18 receives the P-polarized light. One of the image lights is generated by passing through the color liquid crystal panel. Further, as described above, the S-polarized light reflected by the reflection mirror 14 is incident on the second color liquid crystal panel composed of the hologram color filter 16 and the liquid crystal panel 19, and the second color liquid crystal panel The other image light is generated by passing through the liquid crystal panel. The two image lights are combined by the polarization beam splitter 20, and superimposed and projected on the screen 13 via one projection lens 21. In addition, such 1 projection lens 2PBS
In the method, the first color liquid crystal panel and the second color liquid crystal panel
Although the pixel arrangement configuration of the color liquid crystal panel of is the same,
The horizontal scanning directions are opposite to each other.

Then, the P-polarized light transmitted through the polarization beam splitter 5 reaches the first color liquid crystal panel through the reflection mirror 15 and the S reflected by the polarization beam splitter 5 is reflected. The distance that the polarized light reaches the second color liquid crystal panel via the reflection mirror 14 is set to be substantially equal. Specifically, the distance from the polarization beam splitter 5 to the reflection mirror 14 is about 65.
mm, and the distance from the reflection mirror 14 to the hologram color filter 16 is about 35 mm. The distance between the polarization beam splitter 5 and the reflection mirror 15 is about 65 mm, and the distance from the reflection mirror 15 to the hologram color filter 17 is about 35 mm.

As described above, in this embodiment, the optical path length of the P-polarized light transmitted through the polarization beam splitter 5 is such that the polarized light is the reflection mirror 1
5 is the distance to reach the first color liquid crystal panel through 5. The optical path length of the S-polarized light reflected by the polarization beam splitter 5 is the distance until the polarized light reaches the second color liquid crystal panel via the reflection mirror 14. Since both of these distances are set to be substantially equal to each other as described above, the optical path length of the P-polarized light and the optical path length of the S-polarized light are substantially equal to each other, the optical path difference is eliminated, and an image display in which brightness is balanced can be performed. It will be.

[0039]

As described above, according to the present invention,
The difference in the distance (optical path) from the light source to the two color liquid crystal panels is reduced as much as possible, and it is possible to perform image display with a well-balanced luminance.

[Brief description of the drawings]

FIG. 1 is a layout diagram of optical components of a two-projection lens-one-PBS system image display device according to a first embodiment of the present invention.

FIG. 2 is a layout view of optical components of a 2-projection lens 1-PBS system image display device according to a second embodiment of the present invention.

FIG. 3 is a layout view of optical components of a 1-projection-lens-2PBS-type image display device according to a third embodiment of the present invention.

FIG. 4 is a layout view of optical components considered as a specific configuration of the image display device when the hologram color filter is used.

FIG. 5 is a schematic diagram showing the principle of a color filter using a hologram color filter.

[Explanation of symbols]

 1 Light Source 2 Reflector 3,4 Collimator Lens 5 Polarizing Beam Splitter (for Separation) 6,14,15,22 Reflecting Mirror 7,8,16,17 Hologram Color Filter 9,10,18,19 Liquid Crystal Panel 11,12,21 Projection lens 13 Screen 20 Polarizing beam splitter (for synthesis)

Continuation of the front page (51) Int.Cl. ⁶ Identification code Office reference number FI Technical display location G02F 1/1347 G02F 1/1347 H04N 9/30 H04N 9/30

Claims (4)

[Claims] 1. A polarized light transmitted through the polarization beam splitter by causing two lights emitted from one light source to enter the polarization beam splitter, and two color liquid crystal panels for performing color spectroscopy with a hologram color filter. An image obtained through each color liquid crystal panel by separating it into the polarized light reflected by the polarization beam splitter, and guiding one polarized light to one color liquid crystal panel and the other polarized light to the other color liquid crystal panel. In an image display device in which light is superimposed on a screen via a projection lens to display an image, the polarized beam is directed in a direction in which both of the polarized lights approach a surface including a diffraction surface of the hologram color filter. One polarized light is emitted from the splitter and one color liquid crystal panel is passed through the reflection mirror. Led, the image display apparatus characterized by the other of the polarized light is made to be directly guided to the other of the color liquid crystal panel. 2. The longer one of the optical paths for guiding the one polarized light to one color liquid crystal panel and the other optical path for guiding the other polarized light to the other color liquid crystal panel. The image display device according to claim 1, further comprising a transparent plate having a predetermined refractive index and a predetermined thickness for shortening the target optical path length to make both optical path lengths substantially equal. 3. A first polarized light transmitted through the polarization beam splitter by providing two color liquid crystal panels for performing color spectroscopy with a hologram color filter, by causing light emitted from one light source to enter the polarization beam splitter. The light and the second polarized light reflected by the polarization beam splitter are separated, the first polarized light is guided to the first color liquid crystal panel via the first reflecting mirror, and the second polarized light is generated. Second
Led to the second color liquid crystal panel through the reflective mirror of
In the image display device, wherein the image lights obtained through the first and second color liquid crystal panels are combined by a polarization beam splitter and superimposed on a screen via a projection lens to display an image. The distance that the first polarized light transmitted through the splitter reaches the first color liquid crystal panel via the first reflection mirror, and the second polarized light reflected by the polarization beam splitter is the second polarized light. An image display device characterized in that the distance to the second color liquid crystal panel via the second reflection mirror is set to be substantially equal. 4. The right-eye image is displayed on any one of the two color liquid crystal panels, and the left-eye image is displayed on the other one. The image display device according to claim 3.