JPS61150487A - Liquid crystal video projector - Google Patents

Abstract

PURPOSE:To project the screen of a television picture by providing an optical system to synthesize the light radiated from a light source for projection to three primary colors of the light of blue, green and red, an active matrix LCD for modulating the light strength, an optical system to synthesize respective modulated three primary colors and a projecting lens to project the composite image to the screen. CONSTITUTION:A white light from a light source 100 for projection is separated to blue, green and red respectively by a dynamic mirror 104. In an optical path of a blue color, a green color and a red color, active matrix type liquid crystal display devices 114, 116 and 118, and by an electrical signal based on the picture information from the external part, a transmission factor for the light of a liquid crystal is changed. Liquid crystal transmission lights 120, 122 and 124 modulated by respective video signals are synthesized so that the two-dimensional picture element arrangement can be coincident by an optical means of mirrors 126 and 128, half mirrors 130 and 132, etc., again, and projected on a screen 136 by a projecting lens 134.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a large screen display device, and more particularly to a liquid crystal video projector using a transmissive matrix type liquid crystal display device as a liquid crystal light valve.

[Technical background of the invention and its problems]

Increasing the size of television screens has been a desire since televisions were put into practical use. Conventionally, there is a video projector using a CRT as a device for increasing the size of such a television screen. In order to obtain a bright screen, this video projector used a cathode ray tube and lens dedicated to the three primary colors of a color screen, red, green, and blue, but the device was large compared to the brightness of the screen, and It was difficult to make the images projected by the three cathode ray tubes match each other well, and as a result, there was an inconvenience in that the screen size or screen size could not be changed freely.

On the other hand, as another conventional example, a method is known in which an image is written on an image recording medium such as a liquid crystal using an image writing means such as electron beam scanning or laser beam scanning, and the written image is projected using a xenon lamp.

Devices using this method are liquid crystal light pulp (2), (4), (50), (52) as shown in Figures 4 and 5.
Display devices such as, laser beam scanning optical system for image writing (6)
.

(54), image projection optical system (consisting of 81 (56), liquid crystal light pulp (2), (4), (50),
(52) is a liquid crystal layer and a laser beam scanning optical system (6) for image writing.

(54) and a laser light absorption layer that absorbs laser light and transmits it to the liquid crystal layer, and the liquid crystal in the liquid crystal layer is a smectic liquid crystal that exhibits light scattering properties when rapidly cooled after being heated. The image writing laser beam scanning optical system (6) for writing an image on a liquid crystal with a laser beam includes a laser (10), a laser beam modulator (12), a switching mirror (14), and a mirror as shown in FIG. (16), liquid crystal light pulp by scanning ffi-tuned laser light (2), (
4) a detailed X-Y scanning mirror (18) to write the image on;
(20), and a storage lens (22).

(24). Furthermore, in FIG. 4, the image projection optical system (8) that projects the image written on the liquid crystal light pulp (2) (4) onto the screen consists of a xenon lamp (26), a projection lens (28), mirror
(30). Two liquid crystal light pulps are used, and the projected light is divided by a dichroic mirror (a mirror that reflects light in a certain wavelength range and transmits light in other wavelength ranges) to illuminate each liquid crystal light pulp. The reason for this is to display multiple colors (however, full-color display is not possible).

In addition, the image writing laser beam scanning optical system (54) shown in FIG.
) consists of a laser (58), a deflection system (60), an optical lens (62), and an optical switch (64).

Furthermore, the image projection optical system (56) includes a light source (66), a dichroic mirror (68), an optical lens (70), (7
2), mirror (74), (76), filter (78)
, (80). That is, in the apparatus shown in FIG. 5, the image writing laser scanning optical system (6) and the image projection optical system (8) of the apparatus shown in the fourth factor are reversed. In this case as well, two liquid crystal light pulps (
50).

(52) is used and f? It is possible to display in four colors: white, red, green, yellow, and black. Above, the conventional example is shown in Figs. 4 and 5.
As shown in the figure, these devices have the following problems. First, since these devices require a gas laser with a large output, they are extremely large in both weight and volume. TFC, laser beam scanning thermal recording takes a very long writing time per pixel, about 1 second for 1oooxiooo pixel and about 5 seconds for 2000 x 2000 pixels.
Therefore, there was a problem in that it was not possible to display moving images such as television images on one screen per 1/30 second.

Naturally, there was also the problem that nothing could be displayed while the image was being written.

[Purpose of the invention]

The present invention was made in view of the problems of the conventional devices described above, and is a small, light, low-cost liquid crystal video camera that can project high-brightness, large-screen TV images (videos) onto the screen. The purpose is to provide projectors.

[Summary of the invention]

The present invention uses dichroic technology to convert light emitted from a projection light source.
An optical system that separates light into the three primary colors of blue, green, and red using mirrors, etc.; an active matrix LCD for modulating the light intensity of each of the blue, green, and red light paths; and The object of the present invention is to obtain a liquid crystal video projector consisting of a ninth optical system for superimposing and synthesizing images, and a projection system for projecting the synthesized image onto a screen.

〔Effect of the invention〕

According to the present invention, image information can be electrically written to the liquid crystal, and the writing time per screen can be reduced to 1/2.
By using liquid crystal light pulp as an active matrix type liquid crystal display panel that lasts for less than 30 seconds, it becomes possible to project television images on a screen, and it is possible to realize a large-area television image.

The brightness of the screen can be controlled by changing the brightness of the projection light source, and high brightness can also be achieved. Furthermore, active matrix LCDs can achieve high resolution.

That is, the present invention simultaneously satisfies a large screen, high resolution, and high brightness, which was previously impossible, and also makes it possible to display television images.

[Embodiments of the invention]

An embodiment of the present invention will be described below with reference to the drawings. 1st
The figure shows the main parts of a liquid crystal video projector according to the present invention. First, a projection light source (100) that emits white light of, for example, 200 W is provided, and the white light from this projection light source (100) is transmitted to, for example, a lens (102).
The light is made into parallel light beams 7' (then separated into blue, green, and red by a dichroic mirror (104) used in, for example, an image pickup tube).

In this case, the dichroic mirror (104) consists of a blue mirror (106') that reflects blue component light and a red mirror (108) that reflects red component light.

The separated blue light and red light are mirrored (110).

(112), the direction is controlled by blue light, green light,
The red lights are arranged in parallel. Furthermore, in the optical paths of these blue, green, and red lights, there are active matrix liquid crystal display devices (hereinafter referred to as active matrix LCDs) (114) that are driven and controlled by external electrical signals perpendicular to each optical axis. , (116), (
118) is provided. These active matrix LCDs (114), (116), and (118) are, for example, twisted nematic liquid crystals (hereinafter referred to as TNi crystals).
It is composed of 500×500 pixels consisting of thin film transistors arranged in a matrix.

These active matrix LCDs (114)
.

In (116) and (118), the liquid crystal of a given pixel is driven by an electric signal based on external image information, and this driving changes the transmittance of the liquid crystal for light in each pixel. ing. in this case,
The IJ Fuchs CD (114') installed in the optical path of the blue light receives, for example, a video signal containing blue information in an image signal from an external source, and converts the contrast of the incident red light into a red color. It is driven to modulate according to the information of. Similarly, an active matrix LCD (116
) and (118), for example, each video signal having green and red information in the image signal is inputted and modulates the contrast of each incident light. Liquid crystal transmitted light (12
0).

(122), (124) are again mirrors (126)
, (128) and half mirror (130), (132
), etc., so that the two-dimensional pixel arrangement matches, and the two-dimensional pixel arrangement is combined and projected onto the screen 7 (136) by the projection lens (134). Active matrix LCD (114), (11
6) and (118), the writing time per screen is less than 6 seconds, and since a TN liquid crystal is used, the gradation of transmitted light can be controlled analogously, and the contrast ratio is 20:
It is 1 or more.

Therefore, the liquid crystal video projector of this embodiment is NTS
An image having all the hues determined by the C method is displayed at the TV rate and returned.

Next, the active units IJ Fuchs CD (114), (116), and (118) in the above embodiment will be explained in detail.

Figure 2 shows TFT (Th1n Film Tran)
active matrix L using
It is an equivalent circuit diagram of CD. One pixel consists of a TPT switching element (140), a storage capacitor 1t (142), and an ITO
It is composed of a transparent display electrode (144) using (Indium Tin Oxide).

This active matrix LCD has, for example, 500
Consisting of 9 rows x 500 columns, each pixel is connected to an address line (
146), which are connected in the column direction by data lines (148), and each pixel can be selected using an arbitrary address line (146).
This is done by applying a signal to the data line (148). Address line (146), data line (14)
8) is driven (signal application) by an address driver (150) and a data driver (152), respectively. Each address/data driver (1
50) and (152) may be constructed using ICs such as crystalline silicon, polycrystalline silicon, or amorphous silicon. FIG. 3 is a longitudinal cross-sectional view of an active matrix LCD. Since it is a transmission type, the substrate is a transparent glass plate (
160) is used. In the TPT area, a 1500A thick Mo game was placed on a transparent glass plate (160) (1
62) is provided, and a gate insulating layer (164) made of silicon dioxide (5i02) having a thickness of zoox is formed on this Mo gate (162). Furthermore, Mo
Amorphous silicon (166) with a thickness of 3000 Å is formed on (162) via an insulating layer (164), and furthermore, a drain electrode (168) and a source electrode (170) made of Al are formed. ing. Also, in the display area,
A grounding ITO transparent electrode (1) is placed on the transparent glass plate (160).
72), gate insulating layer (164), ITO display electrode (
174) are sequentially formed, and the source electrode (170)
is connected to the display electrode (174). The thickness of the ITO electrodes (172) and (174) for grounding and display is approximately 2000 mm. Si is used in the TPT area and display area.
A base layer (176) made of N is formed, and an alignment layer (178) is further applied thereon.

The substrate section is configured as described above. On the other hand, the counter electrode part is an ITO common counter electrode (180) under the transparent glass plate (180).
82) and an alignment layer (184) are formed. A TV liquid crystal (186) with a thickness of about 10 μm is injected between the substrate part and the counter electrode part to form an active matrix LC.
D is formed. MO game in Figure 3) (1
62) corresponds to the address line (146) in FIG. 2, and similarly the M drain electrode (168) corresponds to the data line. The display electrode (174) is a transparent display electrode (144)
It corresponds to Direction, active matrix LCD
Polarizing plates (not shown) are pasted on both sides.

In the embodiment shown in Fig. 1, alignment of the optical axis is easier than in the conventional method, and color moving images can be freely displayed on screens of any size by finely adjusting the projection/center position. I can do it. In this example, an active matrix type LCD using amorphous silicon TPT is used.
However, a simple matrix type LCD is sufficient for this purpose, and a similar project can be done with an active Φ matrix type LCD using switching elements such as TPT, MOSFET, amorphous silicon Luminum diode, and MIM.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing an embodiment of the present invention, FIGS. 2 and 3 are schematic diagrams explaining the constituent parts of FIG. 1, and FIGS. 4 and 5 are diagrams showing a conventional example. be. 100... Projection light source, 102... Lens, 104
...Dichroic mirror, 106...Blue mirror, 108...Red mirror, 110,112,126
,128...Mirror, 114,116°118...
Active matrix LCD, 120, 122
゜124...Liquid crystal transmitted light, 130, 132...Half mirror, 134...Projection lens, 136...
screen. Representative Patent Attorney Kensuke Norichika and 1 other person Figure 2 Figure 3 Figure 4 Figure 5

Claims (5)

[Claims] (1) A light source that emits light of at least three components of red, green, and blue, a light separation means that separates the light from the light source into three components of red, green, and blue, and a red light separated by the light separation means. a matrix type liquid crystal display device that is inserted into each optical path of three component lights of , green, and blue and modulates the three component lights according to image information; A liquid crystal video projector comprising a light combining means for optically combining light, and a display means for displaying the light combined by the light combining means. (2) The liquid crystal video projector according to claim 1, wherein the light separating means comprises a dichroic mirror. (3) The liquid crystal video projector according to claim 1, wherein the matrix type liquid crystal display device is an active matrix type in which each unit pixel includes a switching element. (4) The matrix type liquid crystal display device is driven by information corresponding to the color component of light incident on the matrix type liquid crystal display device among the image information. LCD video projector as described. (5) The liquid crystal video display according to claim 1, wherein the light modulation by the matrix type liquid crystal display device is performed by varying the light transmittance of the matrix type liquid crystal display device. projector.