Lighting assembly for a backlit electronic display including an integral image splitting and collimating means

• US 5,161,041 A
• Filed: 04/26/1990
• Issued: 11/03/1992
• Est. Priority Date: 04/26/1990
• Status: Expired due to Term

• Current Assignee: 3M Innovative Properties Company (3M Company)
• Original Assignee: OIS Optical Imaging Systems, Inc. (KOCH Industries Incorporated)
• Inventors: Cammarata, Robert M., Abileah, Adiel, Sherman, Charles
• Primary Examiner(s): Miller, Stanley D.
• Assistant Examiner(s): GROSS, ANITA P
• Application Number:
  US07/514,737
• Time in Patent Office: 922 Days
• Field of Search: 350/334, 350/345, 359/40, 359/49
• US Class Current: 349/62
• CPC Class Codes: F21V 5/02 of prismatic shape F21V5/04 takes precedence
• CPC Class Codes: G02F 1/133604 with lamps
• CPC Class Codes: G02F 1/133607 the light controlling member including light directing or refracting elements, e.g. prisms or lenses
• CPC Class Codes: Y10S 315/07 Starting and control circuits for gas discharge lamp using transistors

Abstract

An improved lighting assembly for a backlit electronic display includes an integrally formed image splitting/collimating lens for effectively enlarging the area illuminated by any one or part of one of the lamps of the source of backlighting. Through the use of the improved optical assembly described herein, there is provided a backlit electronic display characterized by fewer lamps, reduced heating, and vastly improved intensity of illumination per unit area in a lower profile package.

Claims

1. In a backlit liquid crystal display which includes a source of light;

a matrix array of rows and columns of liquid crystal picture elements spacedly disposed from one side of said light source; and

means for collimating light, said collimating means operatively disposed between said light source and said matrix array of rows and columns of liquid crystal picture elements;

said liquid crystal display capable of providing an image to a remotely positioned observer;

the improvement comprising, in combination;

an integral collimating and image splitting means for collimating light from said light source and for refracting light rays emanating from said light source to provide two similar images thereof, thereby enlarging the area effectively illuminated by said light source, whereby a bright, uniform, light distribution is provided in a low profile assembly.

2. A display as in claim 1, further including a backreflector operatively disposed on the side of said light source opposite said image splitting/collimating lens.

3. A display as in claim 1, further including means for diffusing light emanating from said light source, said light diffusing means operatively disposed between said image splitting/collimating lens and said rows and columns of liquid crystal picture elements.

4. A display as in claim 1, wherein said light source is a single, elongated, serpentined, tubular lamp arranged in a series of elongated parallel lobes.

5. A display as in claim 1, wherein said light source is a multi-tube lamp array wherein each of said lamps are elongated tubular lamps arranged in substantially parallel fashion.

6. A display as in claim 1, wherein said light source is at least a pair of tubular lamps arranged in a square helical configuration.

7. A display as in claim 1, wherein said image splitting/collimating lens comprises a film having prisms formed on one face thereof.

8. A display as in claim 7, wherein the image splitting/collimating film is laminated to a substrate.

9. A display as in claim 8, wherein said substrate is a thin transparent substrate.

10. A display as in claim 9, wherein the substrate is glass.

11. A display as in claim 1 wherein said integral collimating and image splitting means includes a thin film having faceted prisms formed on one face thereof and wherein said light rays are refracted by the said facets of said prisms.

12. A display as in claim 1, wherein the distance between said two similar images is controlled by the operative spacing of said image splitting/collimating means from said light source.

13. A display as in claim 12, wherein said image splitting/collimating means is operatively spaced from said light source so that said two similar images are immediately adjacent one another.

14. A display as in claim 1, wherein the liquid crystal display is an active matrix liquid crystal display.

15. A display as in claim 1, wherein each liquid crystal picture element comprises a pair of electrodes having liquid crystal material disposed therebetween and at least one threshold device connected at one of the terminals thereof to one of said electrodes.

16. A display as in claim 15, wherein a pair of threshold devices are provided, said threshold devices electrically coupled together at a common node in nonopposing, series relationship.

17. A display as in claim 15, wherein said at least one threshold device comprises a transistor formed from deposited layers of semiconductor material.

18. A display as in claim 15, wherein the threshold devices comprise diodes formed from deposited layers of semiconductor material.

19. A display as in claim 18, wherein the semiconductor material is an amorphous silicon alloy material.

20. A display as in claim 1, wherein the light source comprises lamps arranged in two orthogonal directions.

21. A display as in claim 20, further including two image splitting/collimating lenses arranged to provide perpendicular image splitting effects.

22. A display as in claim 21, wherein said image splitting/collimating lenses each comprise thin films disposed one atop the other, and wherein the dimension in which one of said image splitting/collimating lenses provides an image splitting effect is offset by 90 degrees relative to the other lens.