Display device with a light valve operated in a time division multiplex method

US4265516A · kind A · utility

Assignee

• Siemens Aktiengesellschaft · DE

Inventors

• Waldemar Greubel · Munich, DE
• Hans Krueger · Munich, DE

Key dates

• Filing date: Feb 23, 1979
• Grant date: May 5, 1981
• Expiry date: Feb 23, 1999

Classification

• Technology area (CPC G): Physics
• CPC primary: G02F1/133618
• WIPO field: Optics
• WIPO sector: Instruments

Abstract

A display device includes a light valve that is operated in a time division multiplex method and a fluorescent plate. The light valve may be a liquid crystal with a steep gradient of the contrast-voltage curve so that more multiplex steps are possible. One method of increasing this gradient is to allow only light from a narrow defined spatial angle range to pass through the light valve. In order to produce the narrow light cone that is desired, the invention proposes utilizing a diffusingly reflective layer, which extends parallel to a surface of the fluorescent plate at a finite distance and preferably, the light outlet or exit window of the plate is a surface provided with a dielectric multiple layer which allows the fluorescent light to emerge only in relatively limited spatial angle range. Preferably, these surfaces are the narrow edges of the fluorescent plate.