Liquid crystal display with negative timing signal and dielectric inversion
US4417785A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Jul 20, 1981 |
| Grant date | Nov 29, 1983 |
| Priority date | — |
| Expiry date | Jul 20, 2001 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG02F1/1392
- WIPO fieldOptics
- WIPO sectorInstruments
Abstract
A liquid crystal display device includes a display element containing a liquid crystal display composition for operating in the twisted nematic mode and a two-frequency matrix-addressing circuit for driving the display element. The liquid crystal composition has a critical frequency f.sub.c such that at lower frequencies, the dielectric anisotropy of said composition is positive and at higher frequencies is negative, f.sub.c lying between the low frequency and high frequency components in the output of said circuit. The arrangement of the device is such that a selected picture cell in said display element can be turned off by applying the high frequency component of said output. Other embodiments include a device in which a dichroic dye is incorporated in the composition and an embodiment which contains means for detecting the temperature of the liquid crystal composition. The effect of temperature change on the performance of the device is compensated by changing the frequency of one of the components or by changing the voltage of the output from the circuit.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.