Liquid crystal cells – elements and systems – Particular excitation of liquid crystal – Electrical excitation of liquid crystal
Patent
1995-03-13
1998-01-13
Sikes, William L.
Liquid crystal cells, elements and systems
Particular excitation of liquid crystal
Electrical excitation of liquid crystal
349110, G02F 11343, G02F 11333
Patent
active
057084831
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
The present invention relates to an active matrix type display device equipped with a display pixel electrode array using thin film transistors (referred to as TFTs) as switching elements.
BACKGROUND ART
An ordinary active matrix type liquid crystal display device has a basic structure including an array substrate and counter substrate with a liquid crystal sealed therebetween.
The array substrate includes a matrix array of display pixel electrodes formed on a light-transmitting substrate, such as glass, a plurality of scanning lines formed along rows of the pixel electrodes, a plurality of signal lines along columns of pixel electrodes, a plurality of TFTs connected to control these pixel electrodes according to voltage signals from corresponding scanning and signal lines, and a plurality of storage capacity lines each capacitively coupled to a corresponding pixel electrode via an insulating film.
The counter substrate includes counter electrodes formed on a light-transmitting substrate, such as glass and opposed to the matrix array of display pixel electrodes, and a black matrix for shielding light with respect to an area between the display pixel electrodes. In a case where the liquid crystal display device is used for color display, colored layers are formed on the counter substrate at those areas surrounded with the black matrix and corresponding to the display pixel electrodes.
The liquid crystal display device supplies a select pulse to one of the scanning lines sequentially from a top row on the screen and a non-select pulse to the other scanning lines. Each TFT is set in a conductive state by the select pulse applied from the corresponding scanning line only for a predetermined write period, during which a signal potential applied to the corresponding signal line is written into the corresponding pixel electrode. Further, each TFT is set in a nonconductive state by the non-select pulse applied from the corresponding scanning line only for a predetermined hold period, during which the potential written into the display pixel electrode is held. The hold period is equal to the time from the shutting of the select pulse until it is again applied. The transmittance of the liquid crystal varies in an area between the counter electrode and the display pixel electrode facing the counter electrode, with a difference between the potentials of these two electrodes. The liquid crystal display device two-dimensionally modulates light coming from a back light source by controlling the transmittance distribution of the liquid crystal on the basis of the arrangement of the display pixel electrodes to display an image whose brightness distribution depends upon the transmittance distribution of the liquid crystal.
The aperture ratio of each pixel is represented by the ratio of a light transmission area to the area of a drive circuit for the pixel. Conventionally, the aperture ratio was very low of the order of usually 30 to 40%. Therefore, it was difficult to achieve a desired maximum brightness for the modulated light passed through the liquid crystal display device. As a countermeasure, it may be possible to increase the amount of light emitted from the light source, but this leads to increasing the dissipation power.
It is accordingly the object of the present invention to provide an active matrix type display device which has excellent optical and electrical properties.
DISCLOSURE OF INVENTION
The present invention relates to an active matrix type display device. With the active matrix type display device of the present invention, a gap between the scanning line and the display pixel electrode corresponds to a noneffective pixel area and constitutes an area over which a drive control is not substantially exerted. It is, therefore, necessary that the light shielding means be provided on the light transmitting substrate to prevent light which comes from a light source from leaking toward an observer.
In order to improve the aperture ratio, it is only necessary that the light shielding area,
REFERENCES:
patent: 4753518 (1988-06-01), Clerc
patent: 5159476 (1992-10-01), Hayashi
patent: 5339181 (1994-08-01), Kim et al.
patent: 5402254 (1995-03-01), Sasano et al.
patent: 5459596 (1995-10-01), Ueda et al.
patent: 5508765 (1996-04-01), Nakagawa et al.
patent: 5528395 (1996-06-01), So
Patent Abstracts of Japan, vol. 16, No. 268, Publication No. JP4069622, Publication Date Mar. 4, 1992.
Patent Abstracts of Japan, vol. 17, No. 498, Publication No. JP5127195, Publication Date May 25, 1993.
Patent Abstracts of Japan, vol. 14, No. 59, Publication No. JP1283518, Publication Date Nov. 15, 1989.
Ueda et al., "A High-Aperture-Ratio TFT-LCD With a Shield-Electrode Structure", SID 93 Digest, 1993, pp.739-742.
Kabushiki Kaisha Toshiba
Nguyen Tiep H.
Sikes William L.
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