Light source for liquid crystal display panels utilizing internally reflecting light pipes and integrating sphere

• US 4,735,495 A
• Filed: 12/12/1986
• Issued: 04/05/1988
• Est. Priority Date: 12/12/1986
• Status: Expired due to Fees

• Current Assignee: General Electric Company
• Original Assignee: General Electric Company
• Inventors: Henkes, John L.
• Primary Examiner(s): NOT, DEFINED
• Assistant Examiner(s): Gallivan, Richard F.
• Application Number:
  US06/941,002
• Time in Patent Office: 480 Days
• Field of Search: 350/345, 362/32, 362/296, 362/310, 362/343, 362/347, 362/355
• US Class Current: 349/62
• CPC Class Codes: G02B 6/4214 the intermediate optical element having redirecting reflective means, e.g. mirrors, prisms for deflecting the radiation from horizontal to down- or upward direction toward a device G02B6/4246 takes precedence
• CPC Class Codes: G02B 6/4298 coupling with non-coherent light sources and/or radiation detectors, e.g. lamps, incandescent bulbs, scintillation chambers
• CPC Class Codes: G02F 1/133524 Light-guides, e.g. fibre-optic bundles, louvered or jalousie light-guides

Abstract

This invention relates to a collimated light source for a flat panel liquid crystal display which uses a high intensity light source positioned in an integrating sphere. One or more tapered light pipes have their narrow end(s) positioned in an opening in the integrating sphere. Light from the integrating sphere is internally reflected in the light pipes(s) to produce a relatively collimated output beam which is projected onto one surface of the liquid crystal panel display.

This invention relates to a light source for a liquid crystal panel display and, more particularly, to a collimated light source utilizing light pipes and an integrating light sphere.

Claims

1. A high contrast ratio liquid crystal display including:

(a) a liquid crystal display;

(b) a collimated light source positioned to illuminate one side of said display comprising;

(1) a light integrating sphere having an interior reflecting surface for a source of uncollimated light, said integrating sphere uniformly distributing the uncollimated light, and having an opening to permit a portion of the uncollimated light reflected from the interior surface to exit from the sphere;

(2) tapered elongated light pipe means, one end of said light pipe positioned adjacent to said opening to intercept light emitted from said sphere and the other end of said light pipe means being positioned adjacent to said display whereby light from said sphere is internally reflected in said light pipe means and exits from said other end as a collimated light beam.

2. The liquid crystal display according to claim 1 wherein said light pipe means is tapered to facilitate collimation through internal reflections of light entering said one end.

3. The liquid crystal display according to claim 2 wherein the narrow end of said tapered light pipe means is positioned adjacent to the opening in said sphere.

4. The liquid crystal display according to claim 1 wherein the light pipe means comprises a plurality of light pipes.

5. The liquid crystal display according to claim 4 wherein the wide ends of the tapered light pipes contact each other to form a continuous light emitting surface.

6. A high contrast ration liquid crystal display including:

(a) a liquid crystal display;

(b) a collimated light source positioned to illuminate one side of said display comprising;

(1) a light integrating sphere containing a source of uncollimated light having a plurality of openings to permit a portion of the uncollimated light to exit from said sphere;

(2) elongated light pipe means, comprising a plurality of light pipes, one end of said plurality of light pipes positioned adjacent to one of said plurality of openings.

7. A collimated light source comprising:

(a) a light integrating sphere, said sphere having an internal layer for uniformly distributing and reflecting uncollimated light;

(b) a source of uncollimated light positioned in said sphere;

(c) said sphere having an opening over a portion of its surface to permit a - - portion of the uniformly distributed light from the source to exit from the sphere;

(d) elongated light pipe means having one end positioned adjacent the said opening to intercept light emitted from said sphere;

(e) said light pipe means being tapered for substantially totally internally reflecting light introduced at said one end whereby light emitted at the other end of said light pipe means is substantially collimated.

8. The collimated light souce according to claim 7 wherein said light pipe means is tapered to facilitate collimation through internal reflection of light intercepted at said one end of said light pipe means.

9. The collimated light souce according to claim 7 wherein said light pipe means comprises a plurality of light pipes.

10. The collimated light source according to claim 9 wherein the wide ends of said tapered light pipes contact each other to form a continuous light emitting surface.