Liquid crystal display device with prismatic light transmitting member

• US 5,039,207 A
• Filed: 07/17/1989
• Issued: 08/13/1991
• Est. Priority Date: 07/15/1988
• Status: Expired due to Term

• Current Assignee: Central Research Fund Limited
• Original Assignee: Thorn EMI Plc (Universal Music Group NV)
• Inventors: Green, Bernard J.
• Primary Examiner(s): Hille, Rolf
• Assistant Examiner(s): Clark, S. V.
• Application Number:
  US07/380,467
• Time in Patent Office: 757 Days
• Field of Search: 350/345, 350/258, 350/259, 350/260, 350/261, 350/262, 350/263, 350/264, 350/265, 350/338, 362/31, 362/32, 362/26, 362/27, 362/219, 362/217
• US Class Current: 349/65
• CPC Class Codes: G02F 1/133621 providing coloured light G02F1/133617, G02F1/133533 take precedence
• CPC Class Codes: G02F 1/133622 Colour sequential illumination

Abstract

A liquid crystal device comprises backlighting means to provide illumination from the rear for a liquid crystal panel. The backlighting means has a layer of light-transmitting material formed with a prismatic region at one edge and a plurality of light sources of differing chromatic output, located adjacent the prismatic region.

Claims

1. Apparatus including a plurality of light sources for backlighting a liquid crystal device comprising a light transmitting member formed with an integral prismatic region at one edge thereof, the prismatic region arranged to be receptive to light from the plurality of light sources which light sources are arranged to provide a plurality of chromatic outputs, for providing a substantially uniform illumination of the light transmitting member for each chromatic output.

2. Apparatus according to claim 1 wherein the backlighting member comprises a planar member with two major surfaces thereof and two further respective faces extending therefrom at the one edge such that each of the two further faces protrudes from one of the two major faces at an angle such that the two further faces converge to meet at an apex thereby forming the prismatic region.

3. Apparatus according to claim 1 wherein the backlighting member comprises a planar member with two major surfaces thereof and two further respective faces extending therefrom at the one edge such that each of the two further faces protrudes from one of the two major faces at an angle such that the two further faces diverge thereby to form the prismatic region, the prismatic region having a base portion which is substantially normal to the two major surfaces.

4. Apparatus according to claim 2 wherein the light sources are located adjacent to major faces of the prismatic region such that they lie on a cylindrical plane centred around the apex of the prismatic region.

5. Apparatus according to claim 2 wherein the light transmitting member has a further edge, remote from the one edge thereof, arranged to bear a light reflective coating directing light from the light sources back into the planar member.

6. Apparatus according to claim 5 wherein the further edge is arranged to have a concave curvature as viewed from outside the light transmitting member.

7. Apparatus according to claim 3 wherein the base portion is arranged to bear a coating for providing a dichroic colour separating mirror thereby to permit optical transmission of one chromatic output and to reflect all other chromatic outputs.

8. Apparatus according to claim 1 wherein the light transmitting member includes opposed major surfaces and the substantially uniform illumination of the light transmitting member for each chromatic output is arranged for emission via a major surface thereof, the liquid crystal device being arranged adjacent to the said major surface for emission of each chromatic output, whereby the light sources cannot be viewed directly through the liquid crystal device.

9. Apparatus according to claim 2 wherein the light transmitting member includes opposed major surfaces and the substantially uniform illumination of the light transmitting member for each chromatic output is arranged for emission via a major surface thereof, the liquid crystal device being arranged adjacent to the said major surface for emission of teach chromatic output, whereby the light sources cannot be viewed directly through the liquid crystal device.

10. Apparatus according to claim 3 wherein the light transmitting member includes opposed major surfaces and the substantially uniform illumination of the light transmitting member for each chromatic output is arranged for emission via a major surface thereof, the liquid crystal device being arranged adjacent to the said major surface for emission of each chromatic output, whereby the light sources cannot be viewed directly through the liquid crystal device.