Display device

• US 4,969,732 A
• Filed: 02/23/1989
• Issued: 11/13/1990
• Est. Priority Date: 02/25/1988
• Status: Expired due to Fees

• Current Assignee: Central Research Fund Limited
• Original Assignee: Thorn EMI Plc (Universal Music Group NV)
• Inventors: Wright, Graham L., Dempster, Mark
• Primary Examiner(s): HAROIAN, HARRY
• Application Number:
  US07/314,020
• Time in Patent Office: 628 Days
• Field of Search: 353/77, 353/78, 353/98, 353/99, 353/38, 353/122, 350/169, 350/171, 350/172
• US Class Current: 353/77
• CPC Class Codes: G02B 17/02 Catoptric systems, e.g. image erecting and reversing system
• CPC Class Codes: G03B 21/10 Projectors with built-in or built-on screen
• CPC Class Codes: H04N 5/7408 Direct viewing projectors, e.g. an image displayed on a video CRT or LCD display being projected on a screen

Abstract

A display device includes equipment for projecting light onto a surface. The equipment includes a beam-splitter for effecting partial reflection and partial transmittance of an incident beam. On one side of the beam-splitter are a light source for directing light onto the beam-splitter and a mirror for directing back towards the beam-splitter light reflected therefrom. On the other side of the beam-splitter is a louvre for permitting passage therethrough of light of incident angle relative to a normal to the beam-splitter with in a predetermined restricted range.

Claims

1. Equipment for projecting light onto a surface, the equipment comprising:

beam-splitting means for effecting partial reflection and partial transmittance of an incident beam;

a light source located on one side of the beam-splitting means for directing light onto the beam-splitting means;

mirror means on said one side of the beam-splitting means for directing back towards the beam-splitting means light reflected from the beam-splitting means;

and louvre means located on the other side of the beam-splitting means for permitting passage therethrough of light in a predetermined restricted range of incident angles relative to a normal to the beam-splitting means.

2. Equipment according to claim 1 wherein the light source includes a display panel for producing an image to be projected.

3. Equipment according to claim 1 wherein said predetermined restricted range of incident angles relative to a normal to the beam-splitting means varies with position along the louvre means.

4. Equipment according to claim 3, the louvre means comprising a substrate having a plurality of passageways arranged in side-by-side relation for allowing transmission of light of an incident angle relative to an axis of a passageway within a predetermined range wherein two or more adjacent passageways have a transmission direction at an angle of deviation from a parallel relationship.

5. Equipment according to claim 1 further comprising a Fresnel lens arrangement intermediate the beam-splitting means and the louvre means.

6. Equipment according to claim 1 wherein the beam-splitting means comprises a substrate having alternating reflective and transparent strips.

7. Equipment according to claim 1 wherein an anti-reflection coating is provided on a surface of the beam-splitting means on said other side of the beam splitting means.