Compositions – Liquid crystal compositions
Patent
1997-11-25
1999-12-28
Wu, Shean C.
Compositions
Liquid crystal compositions
25229961, 25229962, 25229963, 25229964, 25229965, 25229966, 25229967, C09K 1952, C09K 1932, C09K 1920
Patent
active
060077379
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
The present invention relates to ferroelectric or antiferroelectric liquid crystal compositions, further smectic liquid crystal compositions, and particularly liquid crystal compositions favorably used for an active matrix driving system. More particularly, the invention relates to liquid crystal compositions which impart voltage gradation (gradation given by variation of voltage) properties to liquid crystal elements.
BACKGROUND ART
Attempts to use liquid crystal elements which utilize electrooptic effect of a twisted nematic (TN) liquid crystal phase (referred to as "TN liquid crystal elements" hereinafter) as display elements of display devices for transient images of moving objects (moving images) have been heretofore made.
The TN liquid crystal elements includes a liquid crystal cell wherein a liquid crystal material capable of exhibiting a twisted nematic (TN) liquid crystal phase (said cell being referred to as "TN liquid crystal cell" hereinafter) is filled in a cell gap.
Most of the recent TN liquid crystal cells used in full color display devices for moving images are driven on an active matrix driving system utilizing TFT (thin film transistor) or MIM (metal insulator metal).
The TN liquid crystal elements having such liquid crystal cells as mentioned above can display images of excellent gradation property, so that they are favorably used for displaying full color images. The term "gradation property" means such a property that brightness intensities between the maximum brightness (white) and the minimum brightness (black) can be stepwise discriminated. For example, by the term "16-gradation" is meant that the brightness of 16 steps can be discriminated from each other between the maximum brightness and the minimum brightness. As the number of the discriminating brightness steps increases, the gradation property becomes better.
The TN liquid crystal elements, however, have a long (slow) electrooptic response time of several tens seconds. Therefore, the display devices using the TN liquid crystal elements cannot follow images of quick motions. Further, the range of the angle at which an image displayed using the TN liquid crystal element is visible is narrow, and when the images displayed by the TN liquid crystal element is observed with an angle outside of a particular range of angle, a problem of the image with reversed gradation or a problem of change in hue of the image takes place.
When the display elements as mentioned above are driven on the active matrix system, the frame frequency in the image display can be set at, for example, not less than 60 Hz, but the electrooptic switching time generally becomes at least several tens msec and occasionally becomes about 200 msec. Therefore, it is difficult to smoothly display moving images by means of the display devices for moving images using the TN liquid crystal elements.
In contrast therewith, liquid crystal elements utilizing electrooptic effect of a ferroelectric liquid crystal phase (referred to as "ferroelectric liquid crystal elements" hereinafter) and liquid crystal elements utilizing electrooptic effect of an antiferroelectric liquid crystal phase (referred to as "antiferroelectric liquid crystal elements" hereinafter) have extremely shorter electrooptic response time than that of the TN liquid crystal elements, and these elements have an advantage in that the range of an angle at which an Image displayed by the elements is visible is wide.
The ferroelectric liquid crystal phase reveals layer structures shown in, for example, FIG. 47(a) to FIG. 47(c).
FIG. 47(a) schematically illustrates an orientation state of liquid crystal molecules 101 which form an antiferroelectric liquid crystal phase between electrodes 102 and 102' provided on respective substrates 106 and 106' of a liquid crystal cell. In general, the electrode 102 and the electrode 102' are formed on one surface of the substrate 106 and one surface of the substrate 106', respectively. When the liquid crystal molecules 101 are orientated, the major axes of
REFERENCES:
patent: 5346646 (1994-09-01), Kawabata et al.
patent: 5352379 (1994-10-01), Nishiyama et al.
patent: 5393460 (1995-02-01), Okabe et al.
patent: 5422039 (1995-06-01), Kawabata et al.
patent: 5534190 (1996-07-01), Johno et al.
patent: 5705094 (1998-01-01), Takeuchi et al.
Fujiyama Takahiro
Hama Hideo
Hirano Chiho
Nishiyama Shinichi
Tatsuki Yuichirou
Mitsui Chemicals Inc.
Wu Shean C.
LandOfFree
Liquid crystal compositions does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Liquid crystal compositions, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Liquid crystal compositions will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2380210