Computer graphics processing and selective visual display system – Plural physical display element control system – Display elements arranged in matrix
Patent
1996-12-19
1998-11-17
Hjerpe, Richard A.
Computer graphics processing and selective visual display system
Plural physical display element control system
Display elements arranged in matrix
G09G 336
Patent
active
058382933
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
The present invention relates to a driving method and system for an antiferroelectric liquid-crystal display device adopting an antiferroelectric liquid crystal as a liquid-crystal layer and having pixels arranged in the form of a matrix.
BACKGROUND ART
As is already known, a liquid crystal, in which dipoles have spontaneous polarizations whose orientations are aligned with each other due to dipole interaction between each pair of dipoles, and the orientations of the spontaneous polarizations are reversed with application of an external electric field, is referred to as a ferroelectric liquid crystal. By contrast, a liquid crystal assuming an antiferroelectric state, in which adjoining dipoles of molecules in a liquid-crystal layer are arranged in anti-parallel with each other so that the spontaneous polarizations of the dipoles will cancel out, is referred to as an antiferroelectric liquid crystal.
In recent years, many studies and attempts of practical use have been made on the former ferroelectric liquid crystal, and the ferroelectric liquid crystal has been adapted to various kinds of products. However, as well known, further improvements are requested in terms of the luminance of a display screen, responsiveness, and angle of visibility.
On the other hand, in the latter antiferroelectric liquid crystal, for example, Japanese Unexamined Patent Publication No. 2-173724 has suggested that the angle of visibility is larger than that permitted by a known nematic liquid crystal, fast response is permitted, and the multiplexing ability is excellent. The antiferroelectric liquid crystal has been under earnest study in various aspects.
The present invention attempts to improve the driving method for a display device adopting the latter antiferroelectric liquid crystal. According to the present invention, a fast, high-contrast, and high-quality display screen can be provided and utilized in a wide range of applications including applications to a liquid-crystal panel, liquid-crystal light shutter array, and the like.
DISCLOSURE OF THE INVENTION
An object of the present invention is to provide a driving method and system for realizing a fast, high-contrast, and high-quality display screen as a display screen for a display device adopting an antiferroelectric liquid crystal.
According to the present invention, an antiferroelectric liquid crystal is interposed between a pair of substrates. The antiferroelectric liquid crystal assumes a first ferroelectric state, a second ferroelectric state that is a ferroelectric state set with application of a voltage that is opposite in polarity to a voltage applied to set the first ferroelectric state, and an antiferroelectric state. One writing of pixels is achieved during at least one scanning period. The scanning period is composed of a selection period during which a select pulse for determining an amount of light transmitted by pixels is applied, a reset period during which a reset pulse for setting the antiferroelectric liquid crystal to a certain state is applied prior to the selection period, and a non-selection period during which the amount of transmitted light determined during the selection period is retained after the selection period.
The antiferroelectric liquid crystal assumes the first or second ferroelectric state during the reset period. During the selection period, the select pulse has 0 V or is a pulse that is opposite in polarity to the reset pulse. During the non-selection period, the antiferroelectric liquid crystal is brought to the antiferroelectric state or a ferroelectric state that is the same as a ferroelectric state set during the reset period.
Preferably, as far as an antiferroelectric liquid-crystal display device having a plurality of scan electrodes and a plurality of signal electrodes is concerned, the antiferroelectric liquid crystal assumes the first or second ferroelectric state during the reset period. During the selection period, the select pulse has 0 V or is a pulse that is opposite in polarity to the reset puls
REFERENCES:
patent: 5136282 (1992-08-01), Inaba et al.
patent: 5408246 (1995-04-01), Inaba et al
patent: 5592190 (1997-01-01), Okada et al.
patent: 5703615 (1997-12-01), Usami
Citizen Watch Co. Ltd.
Hjerpe Richard A.
Laneau Ronald
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