Light diffuser for a liquid crystal display

• US 5,390,085 A
• Filed: 11/19/1993
• Issued: 02/14/1995
• Est. Priority Date: 11/19/1993
• Status: Expired due to Fees

• Current Assignee: Motorola, Inc. (Motorola Solutions, Inc.)
• Original Assignee: Motorola, Inc. (Motorola Solutions, Inc.)
• Inventors: Jelley, Kevin W., Mari-Roca, Gerardo M., King, Jeffrey S., Valliath, George T., Chen, Alan G., Vaughn, Lori
• Primary Examiner(s): Lazarus, Ira S.
• Assistant Examiner(s): HEYMAN, LEONARD
• Application Number:
  US08/155,070
• Time in Patent Office: 452 Days
• Field of Search: 362/26, 362/31, 362/339, 362/276, 362/802
• US Class Current: 362/609
• CPC Class Codes: G02B 6/0018 Redirecting means on the surface of the light guide
• CPC Class Codes: G02B 6/0036 2-D arrangement of prisms, protrusions, indentations or roughened surfaces
• CPC Class Codes: G02B 6/0061 to provide homogeneous light output intensity
• CPC Class Codes: Y10S 362/802 Position or condition responsive switch

Abstract

A light diffuser (100) for illuminating a display (304) comprises a rectangular light distributor (108) which is coupled to a light director (208) located along an edge normal to a major axis (110) of the light distributor (108). The light director (208) directs light received from a lamp (14) into the light distributor (108). The light distributor (108) has a polished, planar top surface (210) and a bottom surface (112) comprising a predetermined serration pattern oriented normal to the major axis (110) of the rectangular light distributor (108). The predetermined serration pattern comprises a plurality of grooves (116, 118, 120) having a predetermined pitch gradient corresponding thereto. The plurality of grooves (116, 118, 120) further have roughened surfaces for diffusing light impinging thereon toward the polished, planar top surface (210) of the light distributor (108). The light impinging on the polished, planar top surface (210) at less than a critical angle is coupled through the polished, planar top surface (210 ) to uniformly illuminate the display (304).

Claims

1. A light diffuser for illuminating a display comprising:

a rectangular light distributor, coupled to a light director located along an edge normal to a major axis of said light distributor, said light director for directing light received from a lamp into said light distributor;

said light distributor having a polished, planar top surface, and a bottom surface comprising a predetermined serration pattern oriented normal to said major axis of said rectangular light distributor;

said predetermined serration pattern comprising a plurality of grooves having a predetermined pitch gradient corresponding thereto;

said plurality of grooves further having roughened surfaces for diffusing light impinging thereon toward said polished, planar top surface; and

whereby the light impinging on said polished, planar top surface at less than a critical angle from said roughened surfaces of said grooves is coupled there through to uniformly illuminate the display.

2. The light diffuser according to claim 1, wherein said rectangular light distributor comprises a transparent material.

3. The light diffuser according to claim 1, wherein said rectangular light distributor has a substantially uniform thickness.

4. The light diffuser according to claim 1, wherein said serration pattern comprises a plurality of linear grooves oriented normal to said major axis of said rectangular light distributor.

5. The light diffuser according to claim 1, wherein said serration pattern comprises a plurality of paired linear grooves oriented at an angle opposite to and bisected by said major axis of said rectangular light distributor.

6. The light diffuser according to claim 1, wherein said serration pattern comprises a plurality of arctuate grooves oriented normal to and bisected by said major axis of said rectangular light distributor.

7. The light diffuser according to claim 1, wherein said pitch gradient increasingly varies a depth of said plurality of grooves continuously from the point proximal to said light collector to the point distal to said light collector.

8. The light diffuser according to claim 1, wherein said pitch gradient varies a depth of said plurality of grooves in a predetermined groups of said grooves from a point proximal to said light collector to a point distal to said light collector.

9. The light diffuser according to claim 1, wherein said light director comprises:

a light collector, positioned below said bottom surface of said light distributor, for collecting the light generated by said lamp; and

a faceted reflecting element for reflecting substantially all of the collected light into said light distributor.

10. A system for back lighting a liquid crystal display, comprising:

a lamp for generating light; and

a light director, optically coupled to said lamp, and further coupled to a light distributor at an edge normal to a major axis thereof, for directing the light received from said lamp into said light distributor, and

said light distributor comprising a transparent material and having a polished, top surface, and a bottom surface comprising a predetermined serration pattern oriented normal to said major axis of said light distributor,

said predetermined serration pattern comprising a plurality of grooves having a predetermined pitch gradient corresponding thereto,

said plurality of grooves further having roughened surfaces for diffusing light impinging thereon toward said polished, planar top surface, and

whereby the light impinging on said polished, planar top surface at less than a critical angle from said roughened surfaces of said grooves is coupled there through to substantially uniformly illuminate the liquid crystal display.

11. The system for back lighting a liquid crystal display according to claim 10, wherein said lamp is tubular.

12. The system for back lighting a liquid crystal display according to claim 10, wherein said light director comprises:

a light collector, positioned below said bottom surface of said light distributor, for collecting the light generated by said lamp; and

a faceted reflecting element for reflecting substantially all of the collected light into said light distributor.

13. The system for back lighting a liquid crystal display according to claim 10, wherein said rectangular light distributor has a substantially uniform thickness.

14. The system for back lighting a liquid crystal display according to claim 10, wherein said serration pattern comprises a plurality of linear grooves oriented normal to said major axis of said rectangular light distributor.

15. The system for back lighting a liquid crystal display according to claim 10, wherein said serration pattern comprises a plurality of paired linear grooves oriented at an angle opposite to and bisected by said major axis of said rectangular light distributor.

16. The system for back lighting a liquid crystal display according to claim 10, wherein said serration pattern comprises a plurality of arctuate grooves oriented normal to and bisected by said major axis of said rectangular light distributor.

17. The system for back lighting a liquid crystal display according to claim 10, wherein said pitch gradient increasingly varies a depth of said plurality of grooves continuously from the point proximal to said light collector to the point distal to said light collector.

18. The system for back lighting a liquid crystal display according to claim 10, wherein said pitch gradient varies a depth of said plurality of grooves in a predetermined groups of said grooves from a point proximal to said light collector to a point distal to said light collector.

19. A communication receiver, comprising:

a receiver for receiving message information including an address;

a decoder, coupled to said receiver, for decoding the address to detect message information directed to the communication receiver;

a display for displaying information including the received message information;

a controller, responsive to said decoder and coupled to said display, for controlling the display of the information including the message information and

a back lighting system, responsive to information being displayed on said display, comprising

a lamp, responsive to said controller, for generating light for illumination;

a light director, optically coupled to said lamp, and further coupled to a light distributor at an edge normal to a major axis thereof, for directing the light received from said lamp into said light distributor, and

said light distributor comprising a transparent material and having a polished, top surface, and a bottom surface comprising a predetermined serration pattern oriented normal to said major axis of said light distributor,

said predetermined serration pattern comprising a plurality of grooves having a predetermined pitch gradient corresponding thereto,

said plurality of grooves further having roughened surfaces for diffusing light impinging thereon toward said polished, planar top surface, and

whereby the light impinging on said polished, planar top surface at less than a critical angle from said roughened surfaces of said grooves is coupled there through to substantially uniformly illuminate the information including the message information being displayed on said display.

20. The communication receiver according to claim 19, wherein said communication receiver further includes a switch activatable by a user and coupled to said controller, for controlling the illumination provided by said lamp.