Computer graphics processing and selective visual display system – Plural physical display element control system – Display elements arranged in matrix
Patent
1998-10-05
2000-10-17
Liang, Regina
Computer graphics processing and selective visual display system
Plural physical display element control system
Display elements arranged in matrix
349174, G09G 336
Patent
active
061338966
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
The present invention relates to a liquid crystal cell used in a liquid crystal display or the like. More particularly, the invention relates to an antiferroelectric liquid crystal cell using an antiferroelectric liquid crystal and having good display qualities.
BACKGROUND ART
A feature of antiferroelectric liquid crystal (hereinafter referred to as AFLC) is that it possesses a large spontaneous polarization Ps compared with other liquid crystal materials. It is known that, in an antiferroelectric liquid crystal cell constructed with AFLC sandwiched between a pair of substrates, AFLC molecules are arranged in layers in the absence of an applied voltage, and whose structure is such that the spontaneous polarization is canceled between each layer. The AFLC material, which was discovered in 1988, was initially introduced as a material that can provide a mode that does not cause burn-in, a phenomenon in which information written before a voltage application persists on a liquid crystal panel, as compared with using the traditional nematic liquid crystal. Since then, development of antiferroelectric liquid crystal panels has proceeded in order to utilize this property of AFLC. Research effort so far has been directed to the development of materials having a large spontaneous polarization Ps and to blending techniques for such materials, to retain fast response and, consequently, the response characteristic has been improved greatly. However, among other characteristics, the contrast, which is the ratio of light transmittance between white display and black display states, still leaves much to be desired.
DISCLOSURE OF THE INVENTION
Accordingly, an object of the present invention is to provide an antiferroelectric liquid crystal cell that has good display qualities by improving the contrast while retaining the fast response and wide viewing angle characteristics of the AFLC mode. It is also an object of the invention to facilitate the fabrication of the liquid crystal cell.
To achieve the above objects, according to the present invention, there is provided an antiferroelectric liquid crystal cell constructed with an antiferroelectric liquid crystal sandwiched between a pair of substrates, wherein the antiferroelectric liquid crystal cell has a layer structure such that when a sinusoidal voltage, as a reference frequency, is applied across the liquid crystal cell and the produced output signal is Fourier transformed, the transformed output voltage contains frequency components at odd and even multiples of the reference frequency, and wherein the optical path length of the liquid crystal cell lies in the range of 100 nm to 800 nm.
ADVANTAGEOUS EFFECTS OF THE INVENTION
According to the present invention, it is possible provide an antiferroelectric liquid crystal panel which, in both the antiferroelectric and ferroelectric phases,
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a diagram showing a voltage waveform for explaining the present invention.
FIG. 2 is a diagram showing a voltage waveform for explaining the present invention.
FIG. 3 is a diagram showing voltage waveforms for explaining the present invention.
FIG. 4 is a diagram showing harmonic components for explaining the present invention.
FIG. 5 is a diagram showing the relationship between voltage and transmittance in an antiferroelectric liquid crystal panel.
FIG. 6 is a diagram showing the structure of an antiferroelectric liquid crystal cell.
FIG. 7 is a block diagram of a circuit configuration for measuring harmonic components.
FIG. 8 is a graph showing harmonic components obtained from an antiferroelectric liquid crystal cell according to the present invention.
FIG. 9 is a graph showing harmonic components obtained from a comparative example different from the present invention.
FIGS. 10(a) and (b) are diagrams showing the layer structures, in cross section, of liquid crystal cells.
FIGS. 11(a) and 11(b) are diagrams showing the layer structures, in cross section, in liquid crystal cells.
FIGS. 12(a) and 12(b) are diagrams
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Citizen Watch Co. Ltd.
Liang Regina
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