Electroluminescent light source and display incorporating same

• US 6,804,058 B1
• Filed: 07/27/2000
• Issued: 10/12/2004
• Est. Priority Date: 12/21/1993
• Status: Expired due to Fees

• Current Assignee: 3M Innovative Properties Company (3M Company)
• Original Assignee: 3M Innovative Properties Company (3M Company)
• Inventors: Weber, Michael F., Ouderkirk, Andrew J., Benson, Olester Jr.
• Primary Examiner(s): Shafer, Ricky D.
• Application Number:
  US09/626,938
• Time in Patent Office: 1,538 Days
• Field of Search: 359/494, 359/495, 359/497, 359/500, 359/599, 313/112, 313/116, 362/19
• US Class Current: 359/489.12
• CPC Class Codes: B29C 55/023 using multilayered plates or sheets
• CPC Class Codes: B29D 11/00 Producing optical elements, e.g. lenses or prisms grinding or polishing of optical elements B24B; constructional form of optical elements G02B; optical parts of spectacles G02C7/00
• CPC Class Codes: B29K 2995/003 Reflective
• CPC Class Codes: B29K 2995/0034 Polarising
• CPC Class Codes: B32B 27/08 of synthetic resin
• CPC Class Codes: B32B 27/36 comprising polyesters
• CPC Class Codes: B32B 7/023 Optical properties
• CPC Class Codes: G02B 27/283 used for beam splitting or combining
• CPC Class Codes: G02B 5/3025 Polarisers, i.e. arrangements capable of producing a definite output polarisation state from an unpolarised input state G02B5/3008, G02B5/3016 take precedence
• CPC Class Codes: G02B 5/305 including organic materials, e.g. polymeric layers
• CPC Class Codes: G02B 5/3083 Birefringent or phase retarding elements G02B5/3008, G02B5/3016 take precedence; systems for polarisation control G02B27/286; manufacturing phase modulating patterns by lithographic processes G03F7/001
• CPC Class Codes: G02F 1/133536 Reflective polarizers G02F1/13362 takes precedence
• CPC Class Codes: G02F 1/133545 Dielectric stack polarisers
• CPC Class Codes: G02F 1/13362 providing polarized light, e.g. by converting a polarisation component into another one

Abstract

A light source comprises an electroluminescent panel and a reflective polarizer that is preferably polymeric, birefringent, or both. The reflective polarizer is positioned to receive light generated by the light generating layer. The reflective polarizer transmits light of a first polarization and reflects light of a second polarization back to the light generating layer. The light generating layer diffusely reflects and randomizes the polarization state of the reflected light and recirculates the reflected light back to the reflective polarizer.

Claims

1. A light source, comprising:

an electroluminescent panel having a light generating layer; and

a birefringent reflective polarizer positioned to receive the light generated by the light generating layer;

wherein the reflective polarizer comprises a multiple layer stack of polymeric materials.

2. A light source, comprising:

an electroluminescent panel having a light generating layer; and

a polymeric reflective polarizer positioned to receive the light generated by the light generating layer;

wherein the reflective polarizer comprises at least one birefringent material.

3. A light source, comprising:

an electroluminescent panel having a light generating layer; and

a polymeric reflective polaizer positioned to receive the light generated by the light generating layer;

wherein the reflective polarizer comprises a multiple layer stack of materials, and at least some of the materials are birefringent.

4. A light source, comprising:

an electroluminescent panel having a light generating layer; and

a birefringent reflective polarizer positioned to receive the light generated by the light generating layer, wherein the reflective polarizer transmits light of a first polarization and reflects light of a second polarization back to the light generating layer, and wherein the light generating layer diffusely reflects and randomizes the polarization state of the reflected light and recirculates the reflected light back to the reflective polarizer;

wherein the reflective polarizer comprises a multiple layer stack of polymeric materials.

5. A light source, comprising:

an electroluminescent panel having a light generating layer; and

a polymeric reflective polarizer positioned to receive the light generated by the light generating layer, wherein the reflective polarizer transmits light of a first polarization and reflects light of a second polarization back to the light generating layer, and wherein the light generating layer diffusely reflects and randomizes the polarization state of the reflected light and recirculates the reflected light back to the reflective polarizer;

wherein the reflective polarizer comprises at least one birefringent material.

6. A light source, comprising:

an electroluminescent panel having a light generating layer; and

a polymeric reflective polarizer positioned to receive the light generated by the light generating layer, wherein the reflective polarizer transmits light of a first polarization and reflects light of a second polarization back to the light generating layer, and wherein the light generating layer diffusely reflects and randomizes the polarization state of the reflected light and recirculates the reflected light back to the reflective polarizer;

wherein the reflective polarizer comprises a multiple layer stack of materials, and at least some of the materials are birefringent.