JPH0827599B2 - Display device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION <Field of Industrial Application> The present invention controls the transmittance of light passing through a mosaic color filter pixel by controlling the transmittance of an electro-optical cell by an electric signal. The present invention relates to an electro-optical display device that performs color display.

<Prior Art> FIG. 3 shows the structure of a color liquid crystal display cell, which has the same structure in both active matrix driving and multiplex driving. One side board 101
Is a mosaic of red, green, and
Blue color filter pixels 500a, 500b, 500c, ... Are formed, and a transparent electrode 20 made of ITO (transparent conductive film) or the like is formed thereon.
1, molecular alignment film made of polyimide film, etc. 3
01 is formed. The molecular orientation film 301 is subjected to orientation treatment by rubbing or the like. The liquid crystal layer 400 comes into contact with the molecular alignment film 301. On the other substrate 100, transparent electrodes 200a, 200b, 200c, ... And a molecular alignment film 300 subjected to alignment treatment are formed thereon. The liquid crystal layer 400 is in contact with the molecular alignment film 300.

Usually, the molecular orientation directions on the two substrates 100 and 101 have a rotation angle of 90 ° with each other. This cell is sandwiched between two polarizing plates. If the polarization axes of the two polarizing plates are parallel to each other, no light will pass through the portions where no voltage is printed. For example,
In FIG. 4, when a voltage higher than the threshold voltage of the liquid crystal is applied between the electrode 200b and the molecular alignment film 301, only green light is transmitted and green display is performed. In this way, color image display is performed by controlling the transmittance of light that passes through the red, green, and blue color filter pixels 500a, 500b, 500c, ....

<Problems to be Solved by the Invention> In the structure of the color liquid crystal display cell described above, display pixel electrodes 200a, 200b, 200c, ... To form the mosaic color filter pixels 500a, 500b, 500c ,. Almost the same processing accuracy is required. Therefore, the color filters 500a, 5
00b, 500c, etc. are usually prepared by a method in which a substrate such as gelatin is covered with a resist layer provided with openings at required portions by photolithography, and a dyeing process is repeated three times. . Since the color filter is manufactured by such a complicated method, the color filter becomes very expensive. There is also a problem that the steps of washing, forming the transparent electrode, and forming the molecular alignment film are greatly restricted by the heat resistance and chemical resistance of the substrate such as gelatin.

As an application of such a liquid crystal display cell, as shown in FIG. 5, the liquid crystal display cell 43 having the above-mentioned structure is used in addition to the reflecting mirror 13 and the light source 23.
In addition, light is emitted by the condenser lens 33, and the liquid crystal display cell 43
There is a projection type color display device in which the image displayed on the screen is enlarged and projected on the screen 76 by the lens 53. However, in this case, since the liquid crystal display cell 43 is close to the light source 23, strong light enters the liquid crystal display cell 43, and as a result,
There is a problem that the color filters 500a, 500b, 500c, ... Discolor.

<Means for Solving the Problems> The present invention provides a light source, an electro-optical cell that performs monochromatic display by controlling the transmittance of light from the light source that passes through the display pixel electrode by an electric signal, and the electro-optical cell. In a display device including a projection lens for magnifying and projecting a monochromatic display image of an optical cell, and a screen for forming an image by projecting the image magnified by the projection lens, the electric power magnified by the projection lens A color filter pixel that selectively transmits light of the three primary colors of red, green, and blue is provided on the viewing side of the screen on which a magnified projection image of the monochromatic display image of the optical cell is formed, depending on the magnification ratio of the projection lens. It is characterized in that a color filter formed by enlarging and forming is arranged.

<Operation> The display device according to the present invention emits light of three primary colors of red, green, and blue to the visible side of the screen on which an enlarged image of a monochrome display image of the image displayed in the electro-optical cell is formed. By disposing a color filter in which color filter pixels that selectively transmit are enlarged and arranged according to the enlargement ratio by the projection lens, a monochromatic display image of the electro-optical cell is enlarged on the screen. After that, it is projected as a color image.

<Example> FIG. 1 shows the optical arrangement of the display device of this example. In the figure, 10 is a reflecting mirror, 20 is a light source, 30 is a condenser lens, 40 is a liquid crystal display cell, 50 is a projection lens, 70 is a color filter, and 80 is a screen.

The reflecting mirror 10, the light source 20, the condenser lens 30, and the projection lens 50 are an optical system for enlarging and projecting the image formed on the liquid crystal display cell 40 onto the screen 80.

The liquid crystal display cell 40 is for performing monochromatic image display by controlling the transmittance of light passing through the display pixel electrode by an electric signal. This liquid crystal display cell 40 is applied between a display pixel electrode arranged in a matrix on one substrate and a counter electrode formed over the other substrate by active matrix driving by a TFT (thin film transistor). The applied voltage is controlled, and a grayscale pattern of black and white is displayed by the electro-optical characteristics of the liquid crystal layer between the polarizing plate and the two substrates. The liquid crystal display cell 40 forms a monochromatic image and does not have the color filter in the color liquid crystal display cell shown in FIG. This liquid crystal display cell 40
May display a monochrome gradation pattern by multiplex driving.

The color filter 70 is disposed in contact with the screen 80, which is the image plane for enlarged projection. This color Herta 70
Is a mosaic of color filter pixels that selectively transmit light of the three primary colors of red, green, and blue.

To explain the operation, the light emitted from the light source 20 and the reflected light from the reflecting mirror 10 are condensed by the condenser lens 30 and enter the liquid crystal display cell 40. The black and white image light generated by the light passing through the liquid crystal display cell 40 passes through the projection lens 50 and further through the color filter 70 to be colored. Then, the black-and-white image formed on the liquid crystal display cell 40 is enlarged and projected as a color image on the screen 80.

In this configuration, since the pixel pattern of the liquid crystal display cell 40 is enlarged and focused on the screen 80,
The color filter 70 in contact with 80 can increase the array pitch of pixels of the three primary colors of red, green, and blue by the magnification of the projection lens 50. Therefore, the requirement for processing accuracy in manufacturing the color filter 70 is significantly reduced, and the color filter 70 can be manufactured by a printing method. For example, the color filter 70 can be manufactured by printing the color filter pixels on the surface of the polyester sheet by offset printing at a pitch of 1 mm in length and width.

Screen the color filter 70 produced by the above method
A display image of a liquid crystal display cell 40 having a display pixel electrode having a vertical and horizontal pitch of 200 μm, which is pasted on 80, is magnified 5 times and projected on a screen 80. The same color reproducibility as that of the display in the projection type color display device (Fig. 4) using the same was recognized, and the decrease in contrast due to ambient light was reduced.

FIG. 2 shows another embodiment. In the figure, 11 is a reflecting mirror, 21 is a light source, 31 is a condenser lens, 41 is a liquid crystal display cell, 51 is a projection lens, 61 is a reflecting mirror, 71 is a color filter, and 81 is a transmissive screen.

The liquid crystal display cell 41 has the same structure as the liquid crystal display cell 40 of the above-described embodiment. The reflecting mirror 61 reflects the image light transmitted through the projection lens 51 and guides it to the transmissive screen 81.

The transmissive screen 81 has a color filter 71, which is composed of mosaic color filter pixels of three primary colors of red, green, and blue, printed on the light emitting surface thereof.

Light from the light source 21 and the reflecting mirror 11 is condensed by the condenser lens 31.
The light is collected by and is irradiated onto the liquid crystal display cell 41. The black and white image light generated by passing through the liquid crystal display cell 41 is projected by the projection lens 51.
Is further reflected by the reflecting mirror 61, and is guided to the color filter 71 on the transmissive screen 81. The black and white image light is colored by the color filter 71, and a color image is enlarged and projected on the transmissive screen 81. A human visually recognizes the image from the right side of the screen 81 in the figure.

In both of the above two embodiments, the light sources 20, 21
As the lamp, a halogen lamp, a fluorescent lamp, a xenon arc lamp, a metal halide lamp, a fluorescent mercury lamp, or the like can be used. Further, the electro-optical cell for forming an image is not limited to the liquid crystal display cell, but may be a PLZT display panel (translucent ceramic display panel) or a light valve using a mechanical shutter.

<Effects of the Invention> As described above, according to the present invention, it is possible to inexpensively manufacture by printing a color filter that was conventionally formed by photolithography. Further, in the production of a liquid crystal display cell which is one of electro-optical display cells, when two substrates are bonded together, the color filter pixels on one substrate and the display electrodes on the other substrate are aligned with each other. There is an advantage that the conventional process is unnecessary, and the yield at the time of manufacturing the liquid crystal display cell is significantly improved.
Furthermore, complicated steps such as cleaning the color filter layer, forming an alignment film on the color filter, and forming a transparent electrode are eliminated. Furthermore, the color filter is arranged at a position distant from the light source, and the light incident on the color filter is light of a magnified image of the display image formed on the electro-optical display cell, so its intensity is small, Therefore,
Since only one color filter needs to be arranged on the projection surface, only one light source is required, the structure is simple, and the device can be made compact. Moreover, since the color filters are arranged on the screen surface on the viewing side, the amount of extra reflected light due to the ambient light applied to the screen other than the projected light is reduced to 1/3 by the color filter. Therefore, a high contrast can be obtained regardless of the ambient light.

[Brief description of drawings]

1 and 2 are diagrams showing a configuration of an embodiment of the present invention, FIG. 3 is a diagram showing a structure of a color liquid crystal display cell of a conventional example, and FIG. 4 is a configuration of a projection type display device of a conventional example. FIG. 10,11,12 …… Reflector 20,21,22 …… Light source 30,31,32 …… Condenser lens 40,41,42 …… Liquid crystal display cell 50,51,52,92 …… Projection lens 61 …… Reflector 70,71,72 …… Color filter 75,80 …… Screen 81,82 …… Transmissive screen

Claims (1)

[Claims] 1. A light source, an electro-optical cell for displaying a single color by controlling the transmittance of light from the light source that passes through a display pixel electrode by an electric signal, and a monochrome display image of the electro-optical cell. In a display device including a projection lens for projecting and a screen for forming and projecting an image magnified by the projection lens, a magnified projection of a monochromatic display image of the electro-optical cell magnified by the projection lens. A color in which color filter pixels that selectively transmit light of the three primary colors of red, green and blue are enlarged and arranged according to the enlargement ratio of the projection lens on the viewing side of the screen on which an image is formed. A display device comprising a filter.