JP2000206485A - Liquid crystal device and its common electrode potential adjustment method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To more simply and with higher accuracy adjust the common electrode potential of a liquid crystal panel typified by flicker adjustment. SOLUTION: A common electrode potential adjustment method in a liquid crystal display uses single color beams for adjusting the common electrode potential of the liquid crystal panels for respective colors, in a three plate system liquid crystal display device causing a full color video to form as image on a screen via a three color separation system of a light source, color transmission filters, total reflection mirrors, etc., the liquid crystal panels for respective colors, a color combining system of a cross dichroic prism and a projection lens.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a liquid crystal display device, and more particularly to a liquid crystal display device capable of easily adjusting a common electrode potential for preventing flicker on a display screen and a method of adjusting the common electrode potential.

[0002]

2. Description of the Related Art The common electrode potential of a liquid crystal display panel has an optimum value unique to the panel irrespective of a fixed level of a video signal to be applied. Accurate adjustment of the common electrode potential is particularly important when determining the correction of the non-linear characteristic (VT characteristic) between the voltage applied to the panel and the transmittance of the panel.

Conventionally, the potential of the common electrode is adjusted until the point where the flicker is minimized is detected with the naked eye or with an optical sensor while the liquid crystal panel is normally separated into three primary colors. Due to the wavelength characteristics, the adjustment in the state where the red light is incident is inconspicuous and therefore easy, while the other color (especially green) light has a disadvantage that it is easily noticeable and difficult to adjust.

[0004]

SUMMARY OF THE INVENTION In view of the above-mentioned problems of the prior art, an object of the present invention is to simplify and adjust a common electrode potential of a liquid crystal panel, which is represented by flicker adjustment, in a liquid crystal display device. It is to realize it accurately.

[0005]

In order to solve the above-mentioned problems, a method of the present invention comprises a light source, a three-color separation system such as a color transmission filter and a total reflection mirror, a liquid crystal panel for each color, and a cross dichroic prism. And a three-panel liquid crystal display device that forms a full-color image on a screen via a projection lens using monochromatic light when adjusting the common electrode potential of the liquid crystal panel for each color. Is a method for adjusting the common electrode potential in the above.

Further, the apparatus according to the present invention comprises a light source, a three-color separation system such as a color transmission filter and a total reflection mirror, a liquid crystal panel for each color, a color synthesis system of a cross dichroic prism, and a screen through a projection lens. In a three-panel liquid crystal display device on which a full-color image is formed, a red transmission filter can be replaced with a red reflection mirror, a blue transmission filter can be replaced with a red transmission filter, and a common electrode of a liquid crystal panel for each color. In adjusting the potential, red light of the three color lights is used.

[0007]

Embodiments of the present invention will be described with reference to the drawings.

FIG. 1 is a diagram showing a configuration of a three-panel liquid crystal display device (projector) according to an embodiment of the present invention.

Normally, as shown in FIG. 1, a three-panel type liquid crystal display device has color transmission filters 5, 6, having various characteristics.
A full-color image is formed on a screen via a color separation system such as total reflection mirrors 4, 7, 9, 10 and the like, liquid crystal panels 11, 12, 13 dedicated to each color, a color synthesis system 14 of a cross dichroic prism, and a projection lens 15. Is done.

Further, each color will be described in detail. Lamp 1
The more white light enters the total reflection mirror 4 via the integrator 2 and the field lens 3, and is totally reflected toward the blue transmission (red-green reflection characteristic) filter 5. The red light of the red-green light reflected by the blue transmission filter 5 further passes through the red transmission filter 6 and irradiates the red liquid crystal panel 11 through the total reflection mirrors 7 and 9 and the relay lens 8. The green light of the red-green light reflected by the blue transmission filter 5 is further reflected by a red transmission (green-blue reflection characteristic) filter 6, and
The light is emitted to the green liquid crystal panel 12. Then, the blue light transmitted through the blue transmission filter 5 is reflected by the total reflection mirror 10 and applied to the blue liquid crystal panel 13.

For adjusting the optimum common electrode potential of each liquid crystal panel, the most severe signal for each liquid crystal panel is adjusted.
(1H inverted signal, etc.) is input in halftone (half brightness), and the potential of the common electrode is monitored until the point where the flicker of twice the vertical cycle (about 30 Hz) is minimized can be detected with the naked eye or with an optical sensor. Up and down to adjust.

However, it is difficult to make an optimal adjustment depending on the intensity and wavelength of the light incident on the liquid crystal panel. For this reason, in the present embodiment, for the sake of convenience, the common electrode potential of the red panel 11 is adjusted as usual on the basis of red, which is easily adjusted, and then the remaining green and blue panels 1 are adjusted.
After replacing the filters 2 and 13 with the following filters and the like, the adjustment may be repeated in the same manner as the red panel.

As for the panel 12 for green, by replacing the red reflection (green-blue transmission characteristic) mirror 6 ′ at the position of the current red transmission filter 6, the current green panel 12 is produced using red light.
Of the common electrode is adjusted. For the blue panel 13, by replacing the red transmission (green-blue reflection characteristic) filter 5 ′ having the opposite characteristic at the position of the current blue transmission filter 5, the common electrode potential of the current blue panel 13 is adjusted using red light. I do.

The performance of the filter before and after replacement
Since the difference in (purity of the monochromatic red component) is directly related to the adjustment accuracy, it is desirable to use the same performance.

As described above, in the adjustment of the common electrode potential, the adjustment for the green and blue panels can be easily performed in the same manner as the adjustment of the red panel by using the red light in common. . Each liquid crystal panel 11
The same video signal is applied to １３13, and it is always a half luminance and every other horizontal line.

[0016]

As described above, according to the present invention,
By using the monochromatic light in common, it is possible to more simply adjust the common electrode potential for all liquid crystal panels.

[Brief description of the drawings]

FIG. 1 shows a three-panel liquid crystal display device according to an embodiment of the present invention.
Diagram showing the configuration of (projector)

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Lamp 2 Integrator 3 Field lens 4, 7, 9, 10 Total reflection mirror 5 Blue transmission (red-green reflection characteristic) filter 5 'Red transmission (green-blue reflection characteristic) filter 6 Red transmission (green-blue reflection characteristic) filter 6' Red reflection (Green-blue transmission characteristics) Mirror 8 Relay lens 11 Liquid crystal panel (for red) 12 Liquid crystal panel (for green) 13 Liquid crystal panel (for blue) 14 Cross dichroic prism 15 Projection lens

Claims (5)

[Claims] 1. A full-color image is formed on a screen via a light source, a three-color separation system such as a color transmission filter and a total reflection mirror, a liquid crystal panel for each color, a color synthesis system of a cross dichroic prism, and a projection lens. In the three-panel liquid crystal display device to be imaged, a method of adjusting the common electrode potential in the liquid crystal display device, wherein monochromatic light of three color lights is used when adjusting the common electrode potential of the liquid crystal panel for each color. 2. The method according to claim 1, wherein the monochromatic light is red light. 3. A color filter such as a color transmission filter or a total reflection mirror.
3. The method according to claim 2, wherein in the color separation system, the red transmission filter is replaced with a red reflection mirror, and the blue transmission filter is replaced with a red transmission filter. 4. A full-color image is formed on a screen via a light source, a three-color separation system such as a color transmission filter and a total reflection mirror, a liquid crystal panel for each color, a color synthesis system of a cross dichroic prism, and a projection lens. In a three-panel liquid crystal display device for imaging, a red transmission filter can be replaced with a red reflection mirror, and a blue transmission filter can be replaced with a red transmission filter. 5. The liquid crystal display device according to claim 4, wherein, when adjusting the common electrode potential of the liquid crystal panel for each color, red light among three color lights is used.