| 摘要 |
A liquid crystal device includes at least three different optical attenuation levels and includes a bistable twisted nematic liquid crystal cell having a first metastable state, which has a first degree of twist and is metastable in the absence of a substantial applied field, and a second metastable state, which has a second degree of twist different from the first degree of twist and is metastable in the absence of a substantial applied field. The device includes an address generator for applying across the cell a field having a waveform which includes a first portion for resetting the liquid crystal to a reset state having the first degree of twist, a second portion for allowing the liquid crystal to relax into a relaxed state having the second degree of twist and a third portion including any one of at least three different waveforms for selecting the at least three different optical attenuation level respectively. In at least one of the attenuation levels, a first portion of the liquid crystal of the cell is in the first metastable state and a second portion of the liquid crystal of the cell is in the second metastable state.
|
