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Nematicliquid crystal electrooptical element and device

A technology of electro-optical components and liquid crystals, applied in instruments, optics, nonlinear optics, etc., can solve the problems of expensive display application systems, incompatibility with high-temperature processing processes, etc., and achieve high update rate, good electro-optical performance and multiplexing performance. , to enhance the effect of bistability

Inactive Publication Date: 2003-08-27
ROLIC AG
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  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

Since TFT fabrication is very delicate, high information capacity LCDs, such as those used in computer monitors, are expensive and limited to the finest display applications
Furthermore, the fabrication of TFTs requires high-temperature processing processes that are incompatible with plastic substrates

Method used

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  • Nematicliquid crystal electrooptical element and device
  • Nematicliquid crystal electrooptical element and device
  • Nematicliquid crystal electrooptical element and device

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Embodiment Construction

[0033] The present invention focuses on new methods and molecular configurations to achieve long-term stability of bistable nematic liquid crystal displays.

[0034] All optically bistable liquid crystal displays reported to date—smectic, cholesteric, or nematic—feature a layer with global alignment, i.e., the alignment of the display between two display substrates. Extend uniformly over the entire area; while the direction of alignment can be different on each substrate.

[0035] In contrast, the present invention chooses a new approach to obtain bistability in conventional twisted nematic LCDs by using non-global alignment geometries. This method surprisingly allows long-term stable and repeatable bistable operation of nematic LCDs.

[0036] Patterned alignment layers on one or both of the substrates of a nematic display enable the generation of different LC configurations that coexist simultaneously and cause bistability in a predefined pixel area (unlike hitherto known N...

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PUM

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Abstract

A liquid crystal electrooptical element comprises a pair of substrates (20, 21) positioned between a pair of polarising plates, electrodes defining pixel areas (1) and alignment layers disposed on the respective opposing inside surfaces of said substrates (20, 21) and a chiral nematic liquid crystal sandwiched between said pair of surfaces. At least one of the alignment layers is patterned in such a way that the azimuth or pretilt or both alignment directions (14 to 17, 16 to 18) are different at the substrate interfaces suppressing the growth of the ground state of the liquid crystal. When an initial electrical pulse is applied, one of the at least two bistable states is reached, wherein the contrast ratio between said bistable states is two or greater. A device with these elements is long-term bistable and does not require electronic refreshing as long as the displayed information is not changed. Therefore, the power consumption of this bistable device is minimal.

Description

technical field [0001] The present invention relates to a nematic liquid crystal electro-optic element and a display device using the element. Background technique [0002] In 1980 Berreman demonstrated transient bistability in twisted nematic LC cells. Fifteen years later Tanaka pointed out a new type of addressing scheme that shortened display addressing and response times. A corresponding ephemeral bistable twisted nematic (BTN) element is disclosed in EP 0 579 247 . [0003] When sandwiched between two substrates with properly aligned layers, Berreman's cells align into different twisted configurations based on the voltage of chiral doped nematic LC molecules. Such an element exhibits three related configurations: with twist angle Φ 0 A high-energy ground state Φ represented by 0 ; twist Φ 1 = Φ 0 The first metastable state Φ at -180° 1 ; and twist Φ 2 = Φ 0 The second metastable state Φ of +180° 2 . [0004] Berreman's work focused on distorting Φ in the grou...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): G02F1/1337G02F1/139
CPCG02F2001/133757G02F1/133753G02F1/1391G02F2001/133761G02F1/1396G02F1/133757G02F1/133761G02F1/1337
Inventor 马丁·斯塔尔德马丁·沙德
Owner ROLIC AG
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