Inorganic thin film compensator for improved gray scale performance in twisted nematic liquid crystal displays and method of making

US5638197A · kind A · utility

Assignee

• Rockwell International Corporation · US

Inventors

• William J. Gunning, III · Newbury Park, US
• Bruce K. Winker · Thousand Oaks, US
• Donald B. Taber · Thousand Oaks, US
• Paul H. Kobrin · Newbury Park, US
• James C. Beedy · Ventura, US
• John P. Eblen, Jr. · Newbury Park, US

Key dates

• Filing date: Sep 30, 1994
• Grant date: Jun 10, 1997
• Expiry date: Sep 30, 2014

Classification

• Technology area (CPC G): Physics
• CPC primary: G02F2413/105
• WIPO field: Optics
• WIPO sector: Instruments

Abstract

An optical O-plate compensation device, in accordance with the invention, uses an inorganic thin film which is grown by physical vapor deposition at oblique incidence. The resulting thin film exhibits a biaxial form birefringence and performs, in a liquid crystal display (LCD), in a similar manner to uniaxial films with its extraordinary axis oriented obliquely at about 45.degree. with respect to the surface of the film. The invention makes possible a significant improvement in the gray scale properties and contrast ratios of liquid crystal displays (LCDs) over a wide range of viewing angles.