Variable contrast, wide viewing angle LCD light-switching filter

• Main Authors: PIRS JANEZ, URANKAR BERNARDA, BAZEC MATEJ, PIRS SILVIJA, MARIN BOJAN, PONIKVAR DUSAN
• Format: Patent
• Language: English
• Published: 24.09.2013
• Subjects: BANDAGES, DRESSINGS OR ABSORBENT PADS; 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; DEVICES PROVIDING PATENCY TO, OR PREVENTING COLLAPSING OF,TUBULAR STRUCTURES OF THE BODY, E.G. STENTS; FILTERS IMPLANTABLE INTO BLOOD VESSELS; FIRST-AID KITS; FOMENTATION; FREQUENCY-CHANGING; HUMAN NECESSITIES; HYGIENE; MEDICAL OR VETERINARY SCIENCE; NON-LINEAR OPTICS; OPTICAL ANALOGUE/DIGITAL CONVERTERS; OPTICAL LOGIC ELEMENTS; OPTICS; ORTHOPAEDIC, NURSING OR CONTRACEPTIVE DEVICES; PHYSICS; PROSTHESES; TECHNIQUES OR PROCEDURES FOR THE OPERATION THEREOF; TREATMENT OR PROTECTION OF EYES OR EARS

A new concept of the LCD light-switching optical filter allowing for very high, electrically controlled, continuously variable light attenuation (up to >=100,000) optimized/symmetrized for the light incidence along the normal to the LCD plane is proposed. The new LCD light-switching optical filter also exhibits very low light attenuation dependence for the oblique incidence of light within a limited cone of angles off the normal incidence direction in compliance with the international safety and quality regulation EN 379 for personal protection equipment. According to the invention the problem is solved by specific, novel modification of the general principle of highly twisted nematic LCDs, allowing for the adaptation of the light transmission/driving voltage characteristics to specific requirements of the driving electronics as well as "symmetrizing" the overall optical birefringent properties, which in turn results in a high degree of their angular compensation.