JPH09218463A - Production of projection type color display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a display device where color slurring and the deterioration of contrast are not caused and a picture having excellent quality is projected forever. SOLUTION: A white light beam emitted from a light source 1 is separated to three primary colors by dichroic mirrors 5 and 6. In a state where the optical paths of red and blue light beams are bent by a reflection mirror 7 and a green light beam is kept as it is, the red, the blue and the green light beams are made incident on liquid crystal light valves 8R, 8G and 8B. The light valves 8R, 8G and 8B modulate the respective color light beams to form the pictures, which are synthesized by a dichroic prism 9 and projected through a projection lens 12. The light valves 8R, 8G and 8B are attached to the prism 9.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a structure of a projection type color display device using a light valve for forming a plurality of images.

[0002]

2. Description of the Related Art Conventionally, a projection type color display device using a plurality of liquid crystal light valves has been described in SID86 digest presentation number 20.4 <announced in May 1986>. , Green and blue color lights are separated, the color lights are image-modulated by a liquid crystal light valve, and then the respective color lights are combined and projected by a projection lens.

[0003]

However, in the above-mentioned prior art, each liquid crystal light valve must be located at the back focus position of the projection lens.
Since each display pixel is displayed by additive mixing of the three primary colors of red, green, and blue, the position of each pixel must be fixed so that the three liquid crystal light valves are located at the same position on the screen. Must. For this reason, a mechanism for fine adjustment must be provided by a mechanical method such as a screw, and the pixel is shifted due to vibration, heat, or the like, resulting in a problem that color shift and contrast are reduced and image quality is reduced. Have.
Further, there is a problem that the readjustment must be performed many times every time a shift occurs, which is very troublesome.

Therefore, the present invention solves such a problem, and an object of the present invention is to eliminate the need for a mechanism for mechanical fine adjustment, to provide no positional shift, to reduce color shift and poor contrast. An object of the present invention is to provide a projection type color display device which can perform projection indefinitely with good image quality.

[0005]

A projection type color display device of the present invention comprises three liquid crystal light valves for image formation, a dichroic mirror system for color separation into three primary colors, and color combination. A projection type color display device including a projection light source and a projection lens is characterized in that a liquid crystal light valve for modulating color-separated color lights of three primary colors and a dichroic prism for combining the modulated color lights are bonded.

[0006]

BEST MODE FOR CARRYING OUT THE INVENTION An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 is a plan view of a projection type color display device of the present invention, and an optical path diagram is also drawn.

[0008] White light emitted from a light source 1 such as a halogen lamp, a xenon lamp, or a metal halide lamp is condensed by a spherical reflector 2 and a condenser lens 3. The condensing lens 3 uses a lens with a large aperture ratio and a short focal length, and increases the solid angle with the light source 1 to increase the light condensing efficiency, and arranges the light source 1 at the focal position of the condensing lens 3. Then, parallel light is obtained. The emitted light is subjected to color separation after heat rays are reduced by the endothermic filter 4.

Color separation is performed by a dichroic mirror,
The red reflection dichroic mirror 5 reflects only the wavelength component of the white light incident at 45 degrees, and the blue reflection dichroic mirror 6 reflects only the blue wavelength component of the white light incident at 45 degrees. The light transmitted through the red reflection dichroic mirror 5 and the blue reflection dichroic mirror 6 becomes light of a green wavelength component. FIG. 2 is a spectroscopic diagram of each dichroic mirror, wherein A shows the characteristics of the red reflecting dichroic mirror 5 and B shows the characteristics of the blue reflecting dichroic mirror 6. Note that color separation may be performed using a dichroic prism 9 described later.

In this manner, among the color lights separated into the three primary colors, the red and blue color lights are bent by the reflecting mirror 7 so that the optical path is bent.
Liquid crystal light valves 8R, 8G, 8 with the color light at the edges as they are
B is incident.

Next, the liquid crystal light valves 8R, 8G, 8B will be described in detail.

In the embodiment of the present invention, an active matrix liquid crystal panel is used as the liquid crystal light valves 8R, 8G, 8B. FIG. 3 is a sectional view showing the structure of the liquid crystal panel, and FIG. 4 is an equivalent circuit diagram of the liquid crystal panel, for explaining the liquid crystal panel.

A transparent pixel electrode 24 made of an ITO film or the like is formed in a matrix on a quartz glass substrate 20. One or two thin film transistors 23 are formed on the pixel electrode 24.
Is connected. Gate line 21 is thin film transistor 2
3 to select one row of the matrix-shaped thin film transistor 23. Source line 22
Is connected to the source of the thin film transistor 23, and writes an amount of electricity according to the image signal to a capacitor formed by the pixel electrode 24 and the counter electrode 26 via the thin film transistor 23.

A transparent counter electrode 26 also made of an ITO film or the like is formed on the glass substrate 25, and a portion other than the opening 29 similar to the pixel electrode 24 is covered with a light shielding layer 28 made of an opaque metal such as nickel. It is shaded.

In general, when a transmission type liquid crystal panel is used, if light enters from the glass substrate 25 side and exits to the quartz glass substrate 20 side, the thin film transistor 23
Can suppress deterioration in performance due to the influence of light.
Reference numeral 30 denotes a polarizing plate.

By arranging the thin-film transistor 23 as an active element for each pixel, when the thin-film transistor 25 is turned on, display data is written into the capacitance formed by the pixel electrode 24 and the counter electrode 26, and the thin-film transistor 23 is turned off. At the time, the display data is accumulated in the capacity in the form of electric charges, and the memory operation is performed, so that a display with good contrast characteristics can be performed. Note that the liquid crystal panel is not limited to the active matrix, and may be, for example, a simple matrix panel driven by time division.

The dichroic prism 9 is obtained by depositing a red reflective layer 10 and a blue reflective layer 11 on both sides of a right-angle prism having two right-angled isosceles triangle surfaces at right angles. Is attached to the center. The characteristics of the red reflection layer 10 and the blue reflection layer 11 are almost the same as those of the dichroic mirror, and have the characteristics shown in FIG.

The aforementioned liquid crystal light valves 8R, 8G, 8B are adhered to the dichroic prism 9 as shown in FIG.

As a bonding method, balsam, an epoxy-based synthetic adhesive, a polyester-based synthetic adhesive, an ultraviolet-curable synthetic adhesive or the like is used. The adhesive has a high transmittance and a refractive index that does not exceed the value of the refractive index of the two substances to be bonded, which can reduce the reflection of light at the interface, resulting in a bright image. Obtainable. The same applies to the method of bonding the dichroic prism 9.

As the alignment, the size of the four right-angle prisms is uniform, so that the distance from the projection lens 12 to the liquid crystal light valves 8R, 8G, 8B becomes constant, and the prism is arranged at the back focus position of the projection lens 12. You. The positional relationship between the upper, lower, left and right pixels is determined by irradiating light from the light source 1 or by using laser light. The pixels of the liquid crystal light valves 8R, 8G, and 8B are overlapped on the screen, and are bonded and fixed by the above-described method, so that color shift and color unevenness due to pixel shift do not occur and maintenance is unnecessary. Becomes In the past, a mechanism for alignment was required, but the structure is simplified because only alignment is required in the manufacturing process.

Each color light image-formed by the liquid crystal light valves 8R, 8G, 8B is reflected by the dichroic prism 9, red light and blue light are reflected, green light is transmitted, and a full-color image is synthesized. Unlike the juxtaposed additive color mixture of a cathode ray tube or the like, the combined image is expressed by the original additive color mixture, so that an image with extremely high saturation is displayed. In addition, since wavelength selection is performed twice for the mirror and the prism,
An image with high color purity can be obtained.

As the projection lens 12, a bright image can be displayed by using a lens having a large aperture ratio.

The circuit section 14 is a television circuit, a driving circuit and a power supply circuit for the liquid crystal light valves 8R, 8G, 8B, and the like. The cooling fan 13 is for discharging heat generated from the light source 21 to the outside. .

FIG. 5 is a plan view showing another embodiment of the projection type color display device of the present invention.

The overall configuration is the same as that of the above-described embodiment, except that the polarizing plates 50 of the liquid crystal light valves 8R, 8G, 8B are taken, one is placed in front of a color-separating dichroic mirror, and the other is placed. Is bonded to the light exit surface of the dichroic prism 9.

The bonding method can be the same as that described above. In this case, a method of color-separating the polarized white light, modulating the image, and synthesizing the white light can reduce the need for six polarizing plates in the above-described embodiment to two.

In the polarizing plate 50 on the light incident side, the amount of transmitted light is about 45% or less, and other light is absorbed and becomes heat,
Adversely affect the liquid crystal light valves 8R, 8G, 8B,
The image quality is degraded due to deterioration of contrast due to heat leak and the like. However, by arranging them at positions separated from the liquid crystal light valves 8R, 8G, 8B, the influence of heat can be reduced.

[0028]

As described above, the present invention has the following effects.

By optically bonding the liquid product light valve to the dichroic prism, there is no need for a mechanism for fine adjustment for alignment, no fine adjustment is required, the structure is simplified, and the cost is reduced. Maintenance becomes unnecessary.

Further, since the reflection of light at the boundary surface is reduced, a bright and high-contrast image can be obtained.

Further, in the second embodiment, in addition to the above effects, by separating the polarizing plate from the liquid crystal panel, the temperature rise of the liquid crystal panel is reduced, and the liquid crystal panel is heated by heat such as heat leak. It is possible to obtain a high-quality image without the inferiority.

[Brief description of drawings]

FIG. 1 is a plan view showing an embodiment of a projection type color display device of the present invention.

FIG. 2 is a diagram illustrating spectral transmission characteristics of a dichroic mirror and a prism.

FIG. 3 is a sectional view showing a structure of a liquid crystal light valve.

FIG. 4 is an equivalent circuit diagram of a liquid crystal light valve.

FIG. 5 is a plan view showing another embodiment of the projection type color display device of the present invention.

[Explanation of symbols]

 5 ... Red reflective dichroic mirror 6 ... Blue reflective dichroic mirror 8R, 8G, 8B ... Liquid crystal light valve 9 ... Dichroic prism 10 ... Red reflective layer 11 ... Blue reflective layer

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[Procedure amendment]

[Submission date] January 8, 1997

[Procedure amendment 1]

[Document name to be amended] Statement

[Correction target item name] Name of invention

[Correction method] Change

[Correction contents]

Title: Method for manufacturing projection type color display device

[Procedure amendment 2]

[Document name to be amended] Statement

[Correction target item name] Claims

[Correction method] Change

[Correction contents]

[Claims]

[Procedure 3]

[Document name to be amended] Statement

[Correction target item name] 0001

[Correction method] Change

[Correction contents]

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of manufacturing a projection type color display device using a light valve for forming a plurality of images.

[Procedure amendment 4]

[Document name to be amended] Statement

[Name of item to be corrected] 0003

[Correction method] Change

[Correction contents]

[0003]

However, in the above-mentioned prior art, each liquid crystal light valve must be located at the back focus position of the projection lens.
Since each display pixel is displayed by additive mixing of the three primary colors of red, green, and blue, the position of each pixel must be fixed so that the three liquid crystal light valves are located at the same position on the screen. Must. For this reason, a mechanism for fine adjustment must be provided by a mechanical method such as a screw, and the pixel is shifted due to vibration, heat, or the like, resulting in a problem that color shift and contrast are reduced and image quality is reduced. Have.
Further, there is a problem that the readjustment must be performed many times every time a shift occurs, which is very troublesome. Therefore, the present invention is to solve such problems, the purpose of which does not require a mechanism for mechanical fine adjustment, there is no positional shift, color shift and deterioration of contrast does not occur. Another object of the present invention is to provide a method of manufacturing a projection type color display device capable of projecting forever with good image quality.

[Procedure Amendment 5]

[Document name to be amended] Statement

[Correction target item name] 0005

[Correction method] Change

[Correction contents]

[0005]

According to the present invention, there are provided a light source, a color light separating means for separating the light from the light source into color lights of a plurality of colors, and a plurality of modulating the respective color lights separated by the color light separating means. A light valve, and a color light synthesizing means for synthesizing the color light modulated by each of the plurality of light valves, the light valve having a plurality of pixels arranged in a matrix, and the color light synthesizing means A method of manufacturing a projection type color display device comprising a prism having a selective reflection film inside, wherein the surface of the prism in the state where the pixels of each of the plurality of light valves are aligned so as to overlap each other on a screen. In contrast, the plurality of light valves are fixed.

[Procedure correction 6]

[Document name to be amended] Statement

[Correction target item name] 0028

[Correction method] Change

[Correction contents]

[0028]

As described above, the present invention has the following effects. Fixing the light valves to the prism surface by fixing the light valves to the prism surface in a state where the pixels of each of the light valves are aligned so as to overlap each other on the screen. After that, there is no need to make fine adjustments, the structure is simple, the cost is reduced, and maintenance is unnecessary.

Claims (1)

[Claims] 1. A projection color display device comprising three liquid crystal light valves for image formation, a dichroic mirror system for separating light into three primary colors and color combination, and a projection color display device comprising a projection light source and a projection lens. A projection type color display device characterized in that a liquid crystal light valve that modulates the separated three primary color lights and a dichroic prism that combines the modulated color lights are bonded together.