JPH05281501A - Liquid crystal projection-type display device - Google Patents

Abstract

PURPOSE:To enhance the brightness of a projected image by roughly doubling the utilization factor of a light source beam, in a liquid crystal projection-type display device. CONSTITUTION:A mirror 4 reflects the light from a light source 2, and a filter 5 selects a visible light, and a polarized beam splitter 6 separate it into a p- polarized beam and a S-polarized beam, and the p-polarized beam is entered into an optical system LA consisting of a color analysis system, a liquid crystal light valve, and a color composition system, and the S-polarized beam is entered into the optical system 1B through a mirror 7. A polarized beam splitter 10 composes the projected original image produced in two optical systems, and a moving mirror 11 reflects it, and a projecting lens 12 projects it on a screen, etc. The moving mirror shifts between a and b in the direction of an arrow separately for each field by the driving of ACT 14, and changes over the position of a projected image up and down separately for each field.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a liquid crystal projection display device, and more particularly to a liquid crystal projection display device which enhances the utilization efficiency of a light source to increase the brightness of a projected image.

[0002]

2. Description of the Related Art In a liquid crystal projection display device, white light from a light source such as a metal halide lamp is decomposed into three colors of red, green and blue by a dichroic mirror and the like, and each is condensed by a condensing lens. The three projection source images are generated by, and then combined into one image, and projected on a screen or the like by the projection lens. The liquid crystal light valve sandwiches the front and back of the liquid crystal panel with two polarizing plates (polarizer and analyzer), and the drive signal applied to the polarizing plates causes linear polarization in one direction from the randomly polarized light flux from the light source. Ingredient (P
Since only polarized light = polarized light in the horizontal direction or S polarized light = polarized light in the vertical direction), the light utilization factor (transmittance) is 50% or less. In addition, TFT (Thin F
In a liquid crystal light valve using an ilm Transistor (thin film transistor), an edge portion (black stripe, etc.) that blocks light provided between the TFT portion on the liquid crystal panel and each pixel
As a result, the aperture ratio becomes about 50%, and further, the area ratio occupied by these TFTs and edges increases relatively with the increase in the number of pixels for improving the image quality of the display device, and the aperture ratio further decreases. Image brightness decreases. In addition, the increase in the number of pixels deteriorates the yield at the time of liquid crystal panel production.

For this reason, two projection display devices are used to generate a projection source image and synthesize and project it on a screen, or the light from a light source is a P-polarized light flux and S.
There is a method of separating the light into polarized light beams, generating a projection source image by each light beam, combining them, and projecting them on a screen. However, in the case of using two projection display devices, there is a problem that it is difficult to align the images on the screen and a space for two is required, and in the case of separating into P-polarized light and S-polarized light. , P-polarized light flux and S-polarized light flux have different distances from the light source to each liquid crystal light valve and from each liquid crystal light valve to the projection lens, the image on the screen may have uneven brightness, color There is a problem that unevenness or pixel shift occurs.

[0004]

In view of the above-mentioned problems, the present invention separates the light from the light source into a P-polarized light beam and an S-polarized light beam, and produces two optical systems for each light beam. To the projection source image with about twice the brightness, and the distance from the light source to the liquid crystal light valve and from the liquid crystal light valve to the projection lens in the two optical systems. Unevenness in the image projected on the screen with the same distance, uneven color,
Alternatively, by avoiding pixel shift and the like, the images from the two optical systems are horizontally shifted by 1/2 dots, and are switched vertically by 1/2 dots for each field, so that the horizontal An object of the present invention is to provide an image equivalent to an image generated by a liquid crystal panel having twice the number of pixels in each of the vertical and vertical directions.

[0005]

In order to solve the above-mentioned problems, the present invention decomposes a light beam from a light source into multiple directions by a first polarization beam splitter, and outputs a projection source image corresponding to each direction. An optical system such as a color separation system for generating light, a liquid crystal light valve, and a color combination system is provided, and light fluxes from the respective optical systems are combined by a second polarization beam splitter and projected onto a screen or the like via a projection lens. , The distance from the light source to each liquid crystal light valve and the distance from each liquid crystal light valve to the projection lens are equal,
An optical system adjusting means for relatively shifting the horizontal pixel position between the respective optical systems by an amount corresponding to ½ dot is provided, and the vertical pixel position of the combined light flux is synchronized with the field frequency by 1
The present invention provides a liquid crystal projection type display device configured by providing means for switching up and down by an amount corresponding to / 2 dots.

[0006]

With the above construction, in the liquid crystal projection display device according to the present invention, the light beam from the light source is separated into the P-polarized light beam and the S-polarized light beam, and the two light beams enter the two optical systems respectively. A projection source image is generated, two generated projection source images are combined, and the result is projected onto a screen or the like by a projection lens. Since the distance from the light source to the liquid crystal light valve of each optical system and the distance from the liquid crystal light valve of each optical system to the projection lens are equal, the combined image has uneven brightness, uneven color, or pixel shift. Is less likely to occur. Further, since the two images are relatively shifted in the horizontal direction by an amount corresponding to 1/2 dot, and at the same time, vertically switched by 1/2 dot in each field,
The image corresponds to an image using a liquid crystal panel having twice the number of pixels in each of the horizontal direction and the vertical direction.

[0007]

Embodiments of the liquid crystal projection display device according to the present invention will be described in detail below with reference to the drawings. FIG. 1 is a conceptual diagram showing a configuration of an embodiment of a liquid crystal projection type device according to the present invention, and FIG. 2 is a configuration diagram of an essential part of an optical system used in a liquid crystal projection type display device according to the present invention.

In FIG. 1, 1A is an optical system for P-polarized light, and 1B is
Is an optical system for S-polarized light. A light source 2 emits white light from a metal halide lamp or the like. Reference numeral 3 denotes a reflector, the inner surface of which is formed into a parabolic shape, and reflects light from the light source 2 so as to become substantially parallel rays. A mirror 4 reflects light from the light source 2 and the like. Reference numeral 5 denotes a filter that blocks ultraviolet rays and heat rays contained in the light from the light source 2 and transmits visible light. Reference numeral 6 denotes a polarization beam splitter, which performs multilayer thin film deposition or the like on an inclined surface of a right-angle prism or the like, and makes incident light P-polarized light (a component that is horizontally polarized with respect to the incident surface) and S-polarized light (vertically polarized with respect to the incident surface). Component), transmits P-polarized light, enters the optical system 1A, and reflects S-polarized light. A mirror 7 reflects the S-polarized light from the polarization beam splitter 6 and enters the optical system 1B. 8A is the output light of the projection source image from the optical system 1A, and 8B is the output light of the projection source image from the optical system 1B. A mirror 9 reflects the light from the optical system 1A. Reference numeral 10 denotes a polarization beam splitter which transmits the light from the mirror 9 and reflects the light from the optical system 1B. 11
Is a moving mirror that moves between a and b for each field as shown by an arrow and reflects the light of the projection source image from the polarization beam splitter 10. A projection lens 12 projects the light from the moving mirror 11 onto a screen or the like. A drive circuit 13 drives an ACT (actuator) 14 according to an input vertical synchronizing signal VD. The ACT 14 moves the position of the moving mirror 11 according to a signal from the drive circuit 13.

FIG. 2 is a configuration diagram of the essential parts of the P-polarized optical system 1A and the S-polarized optical system 1B. The difference between these two optical systems is that the liquid crystal light valves 24, 28 and 32 are configured to transmit P-polarized light according to the drive signal in the optical system 1A and S in accordance with the drive signal in the optical system 1B. It is configured to transmit polarized light, and in both optical systems, the optical path lengths from the light incident position to the liquid crystal light valves 24, 28 and 32 are the same, and the optical paths from the respective liquid crystal light valves are the same. The optical path length to the light emission position is the same.

Reference numeral 21 in the drawing denotes a dichroic mirror which reflects blue light and transmits green light and red light among red, green and blue lights from a light source. The red light transmitted through the dichroic mirror 21 also passes through the dichroic mirror 22, is condensed by the condenser lens 23, enters the liquid crystal light valve 24, is generated in the red projection source image, and is reflected by the mirror 25, The light is reflected by the dichroic mirror 26 and emitted. The dichroic mirror 22 reflects the green light from the dichroic mirror 21. The green light is condensed by the condenser lens 27, enters the liquid crystal light valve 28, is generated as a green projection source image, is reflected by the dichroic mirror 29, passes through the dichroic mirror 26, and is emitted. Further, the blue light reflected by the dichroic mirror 21 is reflected by the mirror 30, condensed by the condenser lens 31, enters the liquid crystal light valve 32 and is generated as a blue projection source image, and the dichroic mirror 29. And passes through and emits light.

Next, the operation of the liquid crystal projection display device according to the present invention will be described. In FIG. 1, the light from the light source 2 and the light reflected by the reflector 3 are emitted as substantially parallel rays, are reflected by the mirror 4, and enter the filter 5. The filter 4 blocks ultraviolet rays, heat rays, etc., transmits visible rays, and enters the polarization beam splitter 6. The polarization beam splitter 6 transmits the P-polarized light through the inclined surface on which the multilayer thin film is deposited, enters the optical system 1A, and reflects the S-polarized light. The S-polarized light is further reflected by the mirror 7, and the optical system
Light enters 1B. Light 8A of the original image generated by the optical system 1A
Is reflected by the mirror 9, enters the polarization beam splitter 10, is combined with the projection source image generated by the optical system 1B, is reflected by the moving mirror 11, and is projected by a projection lens 12 onto a screen or the like. The moving mirror 11 is a drive circuit.
The ACT 14 driven by the signal from 13 is driven so as to move between the arrows a and b for each field, and the position of the reflected image is switched up and down for each field.

Thus, for example, in the case of an image composed of interlaced scanning, the odd field image generated by the optical system 1A and the even field image generated by the optical system 1B are interlaced scanned on the screen. To do. In addition, the pixel position in the horizontal direction is adjusted by appropriately adjusting the registration of the pixel positions of the liquid crystal panels of the optical system 1A and the optical system 1B, and, for example, as shown in FIG. ), And the position of the pixel (+ mark) generated by the optical system 1B is relatively shifted by 1/2 dot in the horizontal direction. As a result, in combination with the up / down switching of the image for each field, the number of pixels in the liquid crystal panel is doubled in the horizontal direction and the vertical direction, respectively, and the projected image can be rendered in high quality.

By making the optical path length from the polarization beam splitter 6 to the light incident position of the optical system 1A and the optical path length from the polarization beam splitter 6 through the mirror 7 to the light incident position of the optical system 1B the same. , The optical path length from the light source 2 to each liquid crystal light valve of the optical system 1A and the optical path length from the light source 2 to each liquid crystal light valve of the optical system 1B become the same, and further, from the light emitting position of the optical system 1A via the mirror 9. By setting the optical path length to the polarization beam splitter 10 and the optical path length to the polarization beam splitter 10 from the light output position of the optical system 1B to be the same, the projection lens 12 is projected from each liquid crystal light valve of the optical system 1A.
And the optical path length from each liquid crystal light valve of the optical system 1B to the projection lens 12 are the same. As a result, in the optical system 1A and the optical system 1B, the light incident on each liquid crystal light valve is under the same conditions (light amount, light distribution, etc.), and the projection source image having substantially the same brightness distribution is generated. The projection source images generated by 1A and the optical system 1B enter the projection lens 12 under the same conditions (pixel position, brightness distribution, color unevenness, etc.), and the projection images are generated by the two optical systems. Brightness unevenness, color unevenness, pixel position shift, and the like due to composition do not occur.

[0014]

As described above, according to the liquid crystal projection display device of the present invention, two optical systems including a color separation system, a liquid crystal light valve, and a color combination system are provided, and one of the optical systems is provided. The liquid crystal light valve generates a projection source image by the light of the P polarization component separated from the randomly polarized light, and the liquid crystal light valve of the other optical system generates the projection source image by the light of the separated S polarization component. Since the output lights of these two optical systems are combined and projected, the brightness of the projected image is approximately twice that of the conventional one. And the above 2
The image by the optical system of the system is relatively shifted by 1/2 dot in the horizontal direction, and the image of the odd field and the image of the even field, which are interlaced, are moved up and down by one.
/ Dot is shifted, so the number of pixels on the liquid crystal panel is 4
An image corresponding to a doubled size is obtained, and a high quality image can be obtained without deteriorating the yield of liquid crystal panel production.
Moreover, since the optical path length from the light source to each liquid crystal light valve of each of the two optical systems is the same, and the optical path length from each of the liquid crystal light valves to the projection lens is the same, it is generated by the two optical systems. There are almost no elements that cause a difference between the projection original images, and therefore, the image projected on the screen is less likely to have uneven brightness, uneven color, or pixel shift.

[Brief description of drawings]

FIG. 1 is a conceptual diagram showing a configuration of an embodiment of a liquid crystal projection type device according to the present invention.

FIG. 2 is a configuration diagram of a main part of an optical system used in the liquid crystal projection display device according to the present invention.

FIG. 3 is a conceptual diagram when the pixel positions of two optical systems are horizontally shifted.

[Explanation of symbols]

 1A P-polarized optical system 1B S-polarized optical system 2 Light source 3 Reflector 4 Mirror 5 Filter 6 Polarization beam splitter 7 Mirror 9 Mirror 10 Polarization beam splitter 11 Moving mirror 12 Projection lens 13 Drive circuit 14 Actuator 21 Dichroic mirror 23 Condensing lens 24 LCD light valve 25 Mirror

Claims (1)

[Claims] 1. A light beam from a light source is decomposed into multiple directions by a first polarization beam splitter, and corresponding to each direction,
An optical system such as a color separation system for generating a projection original image, a liquid crystal light valve, and a color combination system is provided, and the light fluxes from the respective optical systems are combined by a second polarization beam splitter, and are then projected onto a screen or the like via a projection lens. In the projection, the distance from the light source to each liquid crystal light valve and the distance from each liquid crystal light valve to the projection lens are equal, and the horizontal pixel positions between the optical systems are relatively divided by 1/2 dot. A liquid crystal projection display device comprising an optical system adjusting means for shifting, and means for vertically switching the vertical pixel position of the combined light flux in synchronization with a field frequency by an amount corresponding to 1/2 dot.