Computer graphics processing and selective visual display system – Plural physical display element control system – Display elements arranged in matrix
Patent
1997-02-28
1999-08-31
Zimmerman, Mark K.
Computer graphics processing and selective visual display system
Plural physical display element control system
Display elements arranged in matrix
G09G 336
Patent
active
059459719
DESCRIPTION:
BRIEF SUMMARY
FIELD OF THE INVENTION
The present invention relates to a liquid crystal display device using an antiferroelectric liquid crystal display panel that has a plurality of column electrodes and a plurality of row electrodes.
BACKGROUND ART OF THE INVENTION
An antiferroelectric liquid crystal is stable in an antiferroelectric phase or state when left in a condition that no voltage is applied to the liquid crystal (namely, the voltage to be applied to the crystal (substance) is zero). Hereinafter, this stable state will be referred to as a neutral state. An antiferroelectric liquid crystal panel may be configured in such a manner as to effect either a dark display or a bright display in this neutral state. Although antiferroelectric liquid crystal panels of the present invention be applied to both a dark display and a bright display, an antiferroelectric liquid crystal panel of the present invention which is adapted to effect a dark display in the neutral state will be described hereinbelow.
FIG. 16 is an example of a graph illustrating the optical transmittance of an antiferroelectric liquid crystal relative to a voltage applied thereto. In this graph, the abscissa represent the applied voltage; and the ordinate the optical transmittance.
When applying a positive voltage to the crystal, which has been in the neutral state at a point 0, and increasing the positive voltage, the transmittance abruptly increases at a voltage Ft. Then, the transmittance reaches nearly the maximum value at a voltage Fs. Consequently, the crystal is put into a saturated ferroelectric state. Thence, the optical transmittance does not change much even when a higher voltage is applied thereto. Next, when the applied voltage is gradually decreased, the optical transmittance abruptly drops at a voltage At. Further, the transmittance nearly reaches zero at the voltage As. Thus, the crystal returns to an antiferroelectric state. Similarly, if a negative voltage is applied to the crystal when the applied voltage is 0 V, and the applied negative voltage is made more negative, the transmittance abruptly rises at a voltage (-Ft). Then, the transmittance nearly reaches the maximum value at a voltage (-Fs). Thus the crystal is put into a saturated ferrorelectric state. Thence, when gradually the applied negative voltage is reduced to 0 V, the transmittance abruptly drops at a voltage (-At). Further, the transmittance becomes almost zero at a voltage (-As). Thus, the crystal returns to the antiferroelectric state. As above described, there are two causes for a ferroelectric state of the liquid crystal. Namely, one is the application of the positive voltage, and the other is the application of the negative voltage. Hereunder, the ferroelectric state due to the former cause will be referred to as (+) ferroelectric state, while the ferroelectric state due to the latter cause will be referred to as (-) ferroelectric state. Further, .vertline.Ft.vertline. designates a ferroelectric threshold voltage; .vertline.Fs.vertline. a ferroelectric saturation voltage; .vertline.At.vertline. designates an antiferroelectric threshold voltage; and .vertline.As.vertline. an antiferroelectric saturation voltage.
Generally, it is often the case that the curves (namely, the hysteresis curves) of FIG. 16 representing the optical transmittance characteristics of a liquid crystal relative to the voltage applied thereto are obtained by applying thereto a triangular-wave-like voltage which is generated in such a manner that the absolute value of the ratio of a change in this voltage relative to time, namely, the value of .vertline.dV/dt.vertline. is constant. However, in this case, if the value of .vertline.dV/dt.vertline. is changed, the shapes of the hysteresis curves also change. Moreover, the values of the aforementioned quantities As, Ft, Fs and At also vary. It is, accordingly, necessary to specify these values to specify the aforesaid value of .vertline.dV/dt.vertline.. However, in the case of the device of the present invention, data concerning the graph of FIG.
REFERENCES:
patent: 5349367 (1994-09-01), Wakita
patent: 5459481 (1995-10-01), Tanaka et al.
patent: 5598284 (1994-12-01), Kogushi et al.
patent: 5631752 (1997-05-01), Tanaka
patent: 5777593 (1994-12-01), Kondoh
patent: 5805129 (1996-11-01), Inaba et al.
patent: 5815134 (1995-08-01), Nishi
patent: 5835075 (1994-02-01), Nomura et al.
patent: 5838293 (1996-12-01), Kondoh
Ebihara Heihachiro
Imoto Satoshi
Citizen Watch Co. Ltd.
Laneau Ronald
Zimmerman Mark K.
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