Liquid crystal display element includes polariser on front, and reflective element behind liquid crystal cell

• Main Authors: STOENESCU DANIEL N, MARTINOT LAGARDE PHILIPPE, DOZOV IVAN N
• Format: Patent
• Language: English; French
• Published: 16.11.2001
• Edition: 7
• Subjects: DEVICES OR ARRANGEMENTS, THE OPTICAL OPERATION OF WHICH ISMODIFIED BY CHANGING THE OPTICAL PROPERTIES OF THE MEDIUM OF THEDEVICES OR ARRANGEMENTS FOR THE CONTROL OF THE INTENSITY,COLOUR, PHASE, POLARISATION OR DIRECTION OF LIGHT, e.g.SWITCHING, GATING, MODULATING OR DEMODULATING; FREQUENCY-CHANGING; NON-LINEAR OPTICS; OPTICAL ANALOGUE/DIGITAL CONVERTERS; OPTICAL LOGIC ELEMENTS; OPTICS; PHYSICS; TECHNIQUES OR PROCEDURES FOR THE OPERATION THEREOF

The liquid crystal material (40) is contained between two parallel substrates (30,50). Electrical signals are applied to switch between two textures. The structure includes a polariser (10) associated with the front surface of the device. A reflective specular or diffusing element (60) is placed on the rear surface, allowing light to pass through the device twice and return towards the observer. The bi-stable device comprises a liquid crystal material (40) contained between two parallel substrates (30,50), and an aligning system to provide two stable or meta-stable textures. The liquid crystal material may be a liquid crystal, or a mixture of liquid crystal in the nematic phase. Electrical signals are applied to switch between the two textures. The structure includes a polariser (10) associated with the front surface of the device. A reflective specular or diffusing element (60) is placed on the rear surface, allowing light to pass through the device twice and return towards the observer. A compensator (20) is placed between the liquid crystal material and the polariser, the compensator having an optical retardation (dc DELTA nc) which is close to lambda 0/4. La présente invention concerne un dispositif bistable comprenant un matériau cristal liquide, des moyens d'alignement, qui orientent le cristal liquide pour permettre deux textures stables ou métastables, des moyens pour appliquer des signaux électriques qui permettent de commuter entre les textures, un polariseur (10), associé à la face avant du dispositif, placé à l'intérieur ou à l'extérieur de celui-ci, un élément (60) réflectif, spéculaire ou diffusant, placé sur la face arrière du cristal liquide, à l'intérieur ou à l'extérieur du dispositif, permettant à la lumière de passer deux fois dans le dispositif et de retourner vers l'observateur ou vers des éléments optiques supplémentaires, et un compensateur (20), placé entre le polariseur et l'élément réflectif, avec un retard optique dc DELTAnc proche de lambda0 /4.