JPH0658591B2 - LCD color projection device - Google Patents

Description

The present invention relates to a liquid crystal color projector using a TFT, and relates to the arrangement of its color filters.

An object of the present invention is to provide a liquid crystal color projection device with high resolution and to embody a color projection television.

Conventionally, a large-sized projection television is usually enlarged and projected using a projection tube corresponding to the three primary colors. However, the projection tube is expensive and it is difficult to increase the screen brightness. The present invention realizes a relatively inexpensive projection television with a bright screen by using a liquid crystal display.

Hereinafter, the present invention will be described in detail with reference to the drawings.

FIG. 1 shows a liquid crystal display panel used in the projection device of the present invention. TFT on a relatively thick glass substrate 1
Then, the pixel electrode 3 is formed, and the oriented liquid crystal 5 is enclosed between the common electrode 4 and the pixel electrode 3 formed on the entire inner surface of the thin glass or transparent plastic substrate 2. The transparent substrate 6 with the color filter layers 7 and 8 is disposed on the substrate 2 in close contact with each other, and the whole is sandwiched between the upper and lower polarizing plates 9 and 10.
Reference numeral 11 is a liquid crystal sealing portion. The color filter layer 7 is red,
It is a filter that passes one of the three primary colors of blue or green, and the color filter layer 8 is a black filter that blocks light. The black filter is for blocking light and may be a metal vapor-deposited. The three primary color filter layer 7 and the black filter layer 8 form a striped pattern extending in the horizontal direction of the display screen, and just one of the three primary colors comes through the blinds. This relationship is second
Shown in the figure. (A) is a pattern of the color filter layer, where 12 is a portion which does not transmit light and 13 is a filter layer corresponding to one of the three primary colors. Below this, as shown in (b), the TFT 15 and the pixel electrode 14 are arranged. 16 is TF
T is a gate drive line, and 17 is also a drain drive line. At this time, the black filter portion 12 is
Cover the whole and half of the pixel electrode 14. As a result, as will be described later, when the panel is irradiated with parallel rays from behind the filter, the TFT itself is not exposed to the light, so that the TF
It is possible to prevent the characteristic deterioration of T. Furthermore, for example, if two panels with red and black filters are used to display a red image signal and finally they are combined on the screen to obtain a red picture, the interlace of the current TV signal is used. Accordingly, different display panels can be used in the first half and the second half of the interlace, which facilitates signal processing. Of course, the two panel display images are shifted by one horizontal line on the screen and overlapped, so that a picture without stripes can be obtained over the entire screen. By doing so, one pixel on the screen corresponds to half of the pixel electrode of the panel, and the pixel electrode size can be made larger than in the case of forming double density pixels on one display panel, so that the image quality is improved. Is improved. The pixel electrode driven by the TFT can stably hold the alignment of the liquid crystal at a predetermined level even during the non-driving period by storing a signal potential in the electrode capacitance of the liquid crystal. Therefore, if the electrode capacitance of the liquid crystal is small, self-discharge is accelerated, and a stable alignment level cannot be maintained until the next drive signal arrives, resulting in deterioration of image quality. Further, when the TFT is exposed to light, the insulation performance of the TFT is deteriorated, the leak resistance is lowered, and the charge of the electrode capacitance of the liquid crystal is also quickly discharged, resulting in deterioration of image quality.

As in the present invention, a uniform and stable projection image can be obtained by not exposing the TFT to light, enlarging the pixel electrode, and forming the entire screen with two panels for each of the three primary colors.

FIG. 3 is a conceptual diagram of the projection apparatus of the present invention, in which two display panels 18 and 19 for each primary color are irradiated with light from a white light source 20 through a parallel optical path system 22, and a magnifying lens system 23 is provided on a screen 24. Focus on. Two
Reference numeral 1 is a reflecting mirror. As the magnifying projection optical system itself, the one used in the 35 mm slide projector can be used, but a fine adjustment mechanism for aligning a total of 6 magnified images on the screen is necessary.

FIG. 4 is a TV signal block diagram for each primary color. The video signal is separated by the interlace separation circuit 25, the signal for each interlace is passed through the delay circuit systems 26 and 27, and the signal synthesis circuits 28 and 29 are used. After combining, a video signal is supplied to the liquid crystal display panels 30 and 31. As a result, a signal in the interlace period on one side is supplied to one panel without a break, and the image quality does not deteriorate even if the number of pixels is increased and the pixel capacity is reduced. In this case, the delay circuit system includes an AD conversion circuit, a frame memory, a D
It can be formed by an A conversion circuit.

FIG. 5 is a conceptual view of the projection apparatus of the embodiment shown in FIG. 3 as seen from above, and FIG. 6 is shown in FIGS.
It is a perspective view showing the state where the example of the figure was stored in case 40. FIG. 3 is a conceptual diagram for one color, and the state where a pair of liquid crystal display panels 18 and 19 is provided for one color has been described, but three colors (red, red, Green, blue) is required. When the projection device of the embodiment shown in FIG. 3 is viewed from above, as shown in FIG. 5, there are three liquid crystal display panels 18, 18a and 18b,
Since each of these is provided as a pair, it is composed of six liquid crystal panels, as shown in FIG. The images generated by the red, green, and blue liquid crystal display panels are superimposed on the screen 24. However, as described with reference to FIG. 3, the image formed by one liquid crystal display panel 18 of each color is The odd-numbered image of the horizontal line is set, and the image formed by the other liquid crystal display panel 19 is set as the even-numbered image of the horizontal line, which are displayed on the screen 24 in a staggered manner.

Since the projection television has a large screen, it is necessary to increase the number of pixels as much as possible to improve the resolution. In that respect, the proposal of the present invention can sufficiently increase the resolution. Also, the optical system need only have a simple structure, and the screen brightness can be increased more easily than the existing projection tube because it is only necessary to make the light source brighter, and since 6 panels are used, the overall structure can be inexpensive. The utility value is great.

[Brief description of drawings]

FIG. 1 shows a liquid crystal display panel used in the projection device of the present invention. 1 ... Glass substrate 2 ... Transparent substrate 3 ... Pixel electrode 4 ... Common electrode 5 ... Liquid crystal layer 6 ... Filter substrate 7 ... Color filter layer corresponding to one of the three primary colors 8 ... Transmitting light No filter layer 9, 10 ... Polarizing plate 11 ... Sealing part FIGS. 2 (a) and 2 (b) show the positional relationship between the pixel electrode part and the color filter part. 12: Black filter that does not pass light 13: Color filter corresponding to the three primary colors 14: Pixel electrode 15: TFT 16: Drain drive line 17: Gate drive line FIG. 3 shows the projection device of the present invention. It is a conceptual diagram. 18, 19 ...... Liquid crystal panel 20 ...... White light source 21 ...... Reflecting mirror 22 ...... Parallel optical path system 23 ...... Enlarging lens system 24 ...... Screen Fig. 4 is a TV signal block diagram per primary color. 25 ... Interlace separation circuit 26, 27 ... Delay circuit system 28, 29 ... Signal combining circuit 30, 31 ... Liquid crystal display panel FIG. 5 shows the projection device of the embodiment shown in FIG. It is a conceptual diagram. FIG. 6 is a perspective view showing a state where the embodiment of FIGS. 3 and 5 is housed in a housing.

Claims (1)

[Claims] 1. A first liquid crystal modulating means for modulating red light,
Second liquid crystal modulating means for modulating green light, third liquid crystal modulating means for modulating blue light, and the first liquid crystal modulating means,
A magnifying projection optical system for magnifying and projecting an image formed by the second liquid crystal modulating means and the third liquid crystal modulating means, the first liquid crystal modulating means, the second liquid crystal modulating means, and the second liquid crystal modulating means. The liquid crystal modulation means 3 has at least two liquid crystal display panels, and displays the images generated by the respective liquid crystal modulation means in an overlapping manner when the images are magnified and projected on the screen by the magnifying projection optical system, The image formed by one of the liquid crystal display panels of each of the liquid crystal modulation means is an odd-numbered image of the horizontal line of the interlace, and the image formed by the other liquid crystal display panel of each of the liquid crystal modulation means is the interlaced image. A liquid crystal color that displays even-numbered horizontal lines and displays the odd-numbered horizontal lines and the even-numbered horizontal lines by vertically shifting and superimposing them. -Projection device.