High contrast, wide viewing angle LCD light-switching element

US7420631B2 · kind B2 · utility

Assignee

• Institut Jozef Stefan · SI

Inventors

• Janez Pirs · Ljubljana, SI
• Matej Bazec · Izola / Isola, SI
• Silvija Pirs · Ljubljana, SI
• Bojan Marin · Ljubljana, SI
• Andrej Vrecko · Ljubljana, SI

Key dates

• Filing date: Apr 14, 2004
• Grant date: Sep 2, 2008
• Expiry date: Apr 29, 2024

Classification

• Technology area (CPC G): Physics
• CPC primary: G02F2413/14
• WIPO field: Optics
• WIPO sector: Instruments

Abstract

A new concept of the normally open LCD light switching element is proposed, which allows for the superior angular compensation for the light attenuation by using a single simple negative bireffingent c-plate compensation layer. The concept is based on the simultaneous use of highly angularly symmetric STN LC-configuration (preferably 180° twist) and maximal use of the single (preferably ordinary ray) light propagation mode. The solution is best suitable for various light switching applications like LCD automatic protective welding light filters, as well as for multi-segment large display panels, where it provides for excellent uniformity of the light-attenuation in the “dark” state.