JPH04342395A - Liquid crystal display device - Google Patents

Abstract

PURPOSE:To provide a natural display performance with an inexpensive crystal panel with the small number of picture elements by improving the resolution without increasing the number of picture elements and smoothing the unevenness of the edge parts in the display device equipped with the liquid crystal panel with at least more than two delta picture element arrangement structures. CONSTITUTION:A two-phase clock-generation circuit 16 arranging liquid crystal panels 5 and 6 for red and blue lights offset by a half of the horizontal picture element space in the horizontal direction against a liquid crystal panel 4 penetrating a green light and sampling the red and blue components while deviating the phases by 180 deg. against the green component of the video signal according to these position offsets is provided, and the improvement of the resolution and the unevenness of the delta arrangement parts can be reduced by increasing the number of samplings equivalent to the luminance component.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a projection display device using a liquid crystal panel as a light valve.

0002

[Prior Art] In recent years, small TVs, laptop-type OA
The commercialization of devices that use liquid crystal panels as display devices is remarkable. Among these developments, one of the things that is attracting attention is the liquid crystal video projector. Liquid crystal video projectors can be significantly smaller and lighter than conventional CRT projectors, have less geometric distortion in terms of display performance, and are less susceptible to dynamic fluctuations associated with the high-voltage stability of CRTs and the effects of geomagnetism. It has the advantage of ensuring uniform convergence accuracy over the entire display surface, which is not possible in principle.

The structure of a conventional liquid crystal video projector and the driving of the liquid crystal panel will be explained below. FIG. 4 shows an example of the basic configuration of the optical system of a liquid crystal video projector. In FIG. 4, 1 is a light source. 2 and 3 are dichroic filters that separate the white light from light source 1 into the three primary color lights of green, red, and blue; 2 is a blue-transmitting dichroic filter that transmits blue light and reflects green and red light; and 3 is a dichroic filter that transmits green light. It is a green-transmitting dichroic filter that transmits red light and reflects red light. 4, 5, and 6 are liquid crystal panel blocks that control the transmittance of green light, red light, and blue light, respectively, using video signals, and are composed of two polarizing plates and a liquid crystal panel sandwiched between these. 7, 8
is a dichroic filter that combines the three primary colors into white light again; 7 is a blue-transmitting dichroic filter that transmits blue light and reflects green and red light; 8 is a blue-transmitting dichroic filter that transmits green light and reflects blue light,
It is a green-transmitting dichroic filter that reflects red light. 9 and 10 are total reflection mirrors. 11 is a projection lens.

The operation of the liquid crystal video projector configured as described above will be explained below. Figure 3
With this configuration, the white light from the light source 1 is separated into three primary colors of green light, red light, and blue light by the dichroic filters 2 and 3, and after entering the liquid crystal panel blocks 4, 5, and 6, respectively, the white light is separated by the dichroic filters 7 and 8. Since color is synthesized with white light, a color image can be displayed by modulating the light transmittance of each of the liquid crystal panel blocks 4, 5, and 6 with image signals of the three primary colors of green, red, and blue.

FIG. 5 shows a conventional example in which green light, red light, and blue light transmitted through liquid crystal panel blocks 4, 5, and 6 are color-combined and projected onto a screen. Here, it is assumed that the pixel arrangement structure of each liquid crystal panel is a delta arrangement, and the horizontal positions of pixels are shifted in a staggered manner by one-half of the horizontal pixel interval H for each horizontal display line. And LCD panel blocks 4, 5,
6, convergence adjustment is performed by mechanical position adjustment so that the pixel positions are completely coincident. Figure 6(a)
(b) shows a conventional drive circuit for a liquid crystal panel, and (b) shows a timing diagram. In FIG. 6, 12 is a horizontal control circuit, 13 is a vertical control circuit, 14 is a liquid crystal panel source driver, and 15 is a liquid crystal panel gate driver. In the timing diagram, a indicates a video signal viewed in a horizontal period, b indicates a horizontal sampling start pulse SH, and c indicates a video signal sampling clock CK. d is the video signal seen in vertical period, e is the game
To start pulses SV and f indicate shift register gate clock GK. When viewed in a horizontal period, the LCD panel
The driver 14 samples the video signal at the rising edge of the video signal sampling clock CK after the falling edge of the horizontal sampling start pulse SH, and determines the transmittance of each pixel corresponding to the horizontal direction. In the case of the delta arrangement, the pixels on the even-numbered horizontal display lines are shifted from the pixels on the odd-numbered horizontal display lines by one half of the horizontal pixel interval. Therefore, the horizontal control circuit 12 generates a video signal sampling clock CK that is shifted by one-half cycle for even-numbered horizontal display lines. Vertical scanning is performed using a gate start pulse SV by a liquid crystal gate driver 15.
After the fall of GK, the horizontal display lines are sequentially displayed from the first to the last every time the shift register gate clock GK rises.

[0006]

However, the above configuration has the following problems. Originally, when the number of pixels of a liquid crystal panel is the same, the delta arrangement has higher horizontal resolution than the orthogonal arrangement, and there is no significant difference in the Nyquist limit in all directions, so a natural display is possible. However, the resolution in the diagonal direction is inferior to that in the orthogonal arrangement, and when vertical lines are displayed, the edges become jagged as shown in FIG. 4, creating an uneven appearance. These disadvantages become particularly noticeable when the number of pixels is small, resulting in a problem of deterioration of image display performance.

The present invention solves the above conventional problems, and improves the resolution without increasing the number of pixels in the delta array. At the same time, the edges are smoothed to reduce the unevenness of the pixels. The objective is to provide natural image display performance with a smaller number of cheaper liquid crystal panels.

[0008]

Means for Solving the Problems To achieve this object, the liquid crystal display device of the present invention has the following configuration. (1) In a screen in which the transmitted light or reflected light of the liquid crystal panels is positionally synthesized using at least two liquid crystal panels having a delta pixel arrangement, the screen formed by the second liquid crystal panel is different from the screen formed by the first liquid crystal panel. The first and second liquid crystal panels are arranged so as to be offset in the horizontal direction of the screen by half the horizontal pixel interval, and the sampling clocks of the video signals of the first and second liquid crystal panels have different phases. A liquid crystal display device equipped with a two-phase clock generation circuit that supplies a two-phase clock according to the horizontal position of pixels on a liquid crystal panel. (2) Using three liquid crystal panels with a delta pixel array that transmits or reflects the three primary monochromatic lights of red, green, and blue, the first liquid crystal The first, second, and second panels are arranged so that the red and blue monochrome screens formed by the second and third liquid crystal panels are offset in the horizontal direction of the screen by half the horizontal pixel interval with respect to the green monochrome screen formed by the panel. The sampling clock of the video signal of the first liquid crystal panel and the sampling clock of the video signal of the second and third liquid crystal panels are different in phase by 180 degrees.
A liquid crystal display device equipped with a two-phase clock generation circuit that supplies phase clocks.

[0009]

[Operation] With this configuration, the liquid crystal panels for red light and blue light are offset horizontally by half the horizontal pixel interval from the liquid crystal panel that transmits green light. The horizontal positions of red and blue pixels are offset by 1/2 pixel, and at the same time, according to these position offsets, the red and blue components are adjusted by 1 in the horizontal period for the green component of the video signal.
By sampling with a phase shift of 80 degrees, it is possible to increase the equivalent number of samples for the luminance signal, improve the resolution, and at the same time reduce the unevenness of the edge portion due to the delta array.

0010

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings.

In FIG. 1, reference numeral 16 indicates a two-phase clock generation circuit, and reference numerals 4, 5, and 6 indicate liquid crystal panel blocks that control the transmittance of green light, red light, and blue light, respectively.

The operation of the liquid crystal display device constructed as described above will be explained. First, in the timing diagram shown in FIG. 2, c and d indicate the outputs CK1 and CK2 of the two-phase clock generation circuit 16, the output CK1 is sent to the liquid crystal panel block 4 (green), and the output CK2 is sent to the liquid crystal panel block 5 (red). and is supplied to the liquid crystal panel block 6 (blue) as a video signal sampling clock.

FIG. 3 shows an example of a screen in which green light, red light, and blue light transmitted through the liquid crystal panel blocks 4, 5, and 6 are combined in color and projected onto a screen. The red and blue screens indicated by broken lines are offset to the right by one-half of the horizontal pixel interval with respect to the single-color green screen indicated by solid lines. Among the two-phase clocks shown in Figure 1 for the above offset pixels, if CK1 samples the green component of the video signal, and CK2 samples the red and blue components of the video signal and displays each pixel, sampling for the luminance signal is possible. The frequency is equivalently doubled and the horizontal resolution is improved. FIG. 3 shows an example of vertical line display with the above configuration. 1/2 pixel width with green or magenta (red,
However, since the pixel arrangement is a delta arrangement, green and magenta (red, blue) alternate between odd and even numbers on the horizontal display line, and as a result, the color is visually integrated spatially. The component is relaxed and recognized as a luminance component. Figure 5
It is clear that the edge portion is smoothed and the unevenness is reduced compared to the conventional example shown in FIG.

As described above, according to this embodiment, the liquid crystal panels 5 and 6 for red light and blue light are offset in the horizontal direction by one half of the horizontal pixel interval with respect to the liquid crystal panel 4 that transmits green light. At the same time, by sampling the red and blue components with a 180 degree phase shift with respect to the green component of the video signal according to these position offsets, the equivalent number of samplings for the luminance signal is increased, and at the same time the resolution is improved and the delta It is possible to reduce the unevenness of the edge portion due to the arrangement.

[0015]

As described above, the present invention uses a plurality of liquid crystal panels having a delta pixel arrangement so that the screen formed by one liquid crystal panel and the other liquid crystal panel is separated by half the horizontal pixel interval in the horizontal direction of the screen. By providing a two-phase clock generation circuit that supplies two-phase clocks with a 180-degree difference in phase as the sampling clock for the video signal of each LCD panel, it is possible to create a cheaper LCD panel with a smaller number of pixels. By using this method, it is possible to realize an excellent liquid crystal display device that improves resolution and reduces the unevenness of the edge portion caused by the delta arrangement.

[Brief explanation of drawings]

FIG. 1 is a block diagram of a liquid crystal display device according to an embodiment of the present invention.

[Fig. 2] Timing diagram of liquid crystal drive control waveforms in one embodiment of the present invention

FIG. 3 shows the green color of the liquid crystal display device in one embodiment of the present invention.
Diagram showing an example of a red and blue composite screen

[Figure 4] Basic configuration diagram of the optical system of a liquid crystal video projector

[Figure 5] A diagram showing an example of a composite screen of green, red, and blue on a conventional liquid crystal display device.

[Figure 6] (a) Block diagram of a conventional liquid crystal drive control circuit (
b) Timing diagram of conventional liquid crystal drive control waveforms

[Explanation of symbols]

4. Green LCD panel block 5. Red LCD panel block 6. Blue LCD panel block 16 2-phase clock generation circuit

Claims (2)

[Claims] Claim 1: In a screen in which at least two liquid crystal panels having a delta pixel arrangement are used to positionally synthesize the transmitted light or reflected light of the liquid crystal panels, the second liquid crystal panel is positioned relative to the screen formed by the first liquid crystal panel. first and second liquid crystal panels arranged such that the screen is offset in the horizontal direction of the screen by one half of the horizontal pixel interval;
A liquid crystal display device comprising a two-phase clock generation circuit that supplies a two-phase clock whose phase corresponds to the horizontal position of a pixel of each liquid crystal panel as a sampling clock of a video signal of a second liquid crystal panel. 2. In a screen in which three liquid crystal panels each having a delta pixel array that transmits or reflects the three primary monochromatic lights of red, green, and blue are used, the transmitted light or reflected light is positionally synthesized. The first and second screens are arranged such that the red and blue monochrome screens formed by the second and third liquid crystal panels are offset in the horizontal direction of the screen by one-half of the horizontal pixel interval with respect to the green monochrome screen formed by the liquid crystal panel. , a third liquid crystal panel, and a sampling clock of the video signal of the first liquid crystal panel and a sampling clock of the video signal of the second and third liquid crystal panels with respect to the sampling clock of the video signal of the first liquid crystal panel.
A liquid crystal display device equipped with a two-phase clock generation circuit that supplies two-phase clocks with different degrees.