(12) United States Patent ao) Patent No.: us 6,567,065 Bi
Kondoh et al. (45) Date of Patent: May 20,2003
(54) FERROELECTRIC LIQUID CRYSTAL
DISPLAY AND METHOD OF DRIVING THE
SAME
(75) Inventors: Shinya Kondoh, Tokorozawa (JP);
Shigekazu Takahashi, Kawaguchi (JP)
(73) Assignee: Citizen Watch Co., Ltd., Tokyo (JP)
( * ) Notice: Subject to any disclaimer, the term ol this patent is extended or adjusted under 35 U.S.C. 154(b) by 0 days.
(21) Appl. No.: 09/381,329
(22) PCT Filed: Aug. 6, 1998
(86) PCT No.: PCT/JP98/03511
§ 371 (c)(1),
(2), (4) Date: Sep. 20, 1999
(87) PCT Pub. No.: WO00/08518 PCT Pub. Date: Feb. 17, 2000
(30) Foreign Application Priority Data
Jun. 20, 1997 (JP) 9-164151
(51) Int. CI. G09G 3/36
(52) U.S. CI 345/97; 345/99; 345/103
(58) Field of Search 345/97, 103, 87,
345/88, 89, 208, 99; 349/78
(56) References Cited
U.S. PATENT DOCUMENTS
4,857,906 A * 8/1989 Conner 345/97
4,870,398 A * 9/1989 Bos 345/97
5,233,338 A 8/1993 Surguy 340/784
5,349,367 A * 9/1994 Wakita 345/97
A lerroelectric liquid crystal display comprises: a lerroelectric liquid crystal display element which includes a lerroelectric liquid crystal that is sandwiched between a pair ol substrates having a plurality ol scanning electrodes and signal electrodes deposited respectively on the opposing surfaces thereol; and a light source which successively emits a plurality ol different colors ol light. In the thus constructed lerroelectric liquid crystal display, a scanning period (TS) during which the light source emits light ol one ol the plurality ol colors is divided into two periods, ol which the first period (SCI) includes a selection period lor determining a display state and a non-selection period for holding therethrough the display state selected during the selection period, and the second period (SC2), constituting the remainder ol the scanning period, includes a selection period for forcing the display state into a black display state and a non-selection period for holding therethrough the black display state selected during the selection period.
11 Claims, 15 Drawing Sheets
