Bulk diffuser for flat panel display

• US 6,908,202 B2
• Filed: 10/03/2002
• Issued: 06/21/2005
• Est. Priority Date: 10/03/2002
• Status: Expired due to Term

• Current Assignee: SABIC Global Technologies BV (Government of Saudi Arabia)
• Original Assignee: General Electric Company
• Inventors: Olczak, Eugene G., Hariharan, Ramesh, Hay, Grant, Schottland, Philippe, Graf, John F.
• Primary Examiner(s): O'Shea, Sandra
• Assistant Examiner(s): Tsidulko, Mark
• Application Number:
  US10/065,319
• Publication Number:
  US 20040066645A1
• Time in Patent Office: 992 Days
• Field of Search: 362/26, 362/31, 362558-561, 349/64, 349/65, 349/112, 359/559, 359/601, 359/49, 428/327, 428/332, 428/338, 428/412, 523/223
• US Class Current: 362/26
• CPC Class Codes: C08L 2666/02 Organic macromolecular compounds, natural resins, waxes or and bituminous materials
• CPC Class Codes: C08L 27/18 Homopolymers or copolymers or tetrafluoroethene
• CPC Class Codes: C08L 33/08 Homopolymers or copolymers of acrylic acid esters
• CPC Class Codes: C08L 33/10 Homopolymers or copolymers of methacrylic acid esters
• CPC Class Codes: C08L 69/00 Compositions of polycarbonates; Compositions of derivatives of polycarbonates
• CPC Class Codes: C08L 83/06 containing silicon bound to oxygen-containing groups C08L83/12 takes precedence
• CPC Class Codes: G02B 5/0242 by means of dispersed particles
• CPC Class Codes: G02B 5/0278 used in transmission
• CPC Class Codes: G02B 6/0031 Reflecting element, sheet or layer
• CPC Class Codes: G02B 6/0038 Linear indentations or grooves, e.g. arc-shaped grooves or meandering grooves, extending over the full length or width of the light guide
• CPC Class Codes: G02B 6/0051 Diffusing sheet or layer
• CPC Class Codes: G02B 6/0053 Prismatic sheet or layer; Brightness enhancement element, sheet or layer
• CPC Class Codes: G02B 6/0055 Reflecting element, sheet or layer
• CPC Class Codes: G02B 6/0071 with elongated shape, e.g. tube

Abstract

The invention features a bulk light diffuser material. The bulk light diffuser material may be a sheet or film comprising about 95 to about 99.8 percent by weight of polycarbonate and about 0.2 to about 2.5 percent by weight of a particulate light diffusing component, based on the total weight of the polycarbonate and the light diffusing particles. The sheet material has a percent transmittance of at least 70% and a haze of at least 10% measured according to the American Society for Testing and Materials (ASTM) standard D 1003.

Claims

1. A bulk light diffuser material comprising:

about 95 to about 99.8 percent by weight of a polycarbonate and about 0.2 to about 5 percent by weight of light diffusing particles, based on the total weight of the polycarbonate and of the light diffusing particles, wherein the light diffusing particle have a refractive index of 1.43 to 1.49; and

wherein the bulk light diffuser material has a percent transmittance of at least 70% and a haze of at least 10%.

2. The bulk light diffuser material as set forth in claim 1 wherein the light diffusing particles comprise a poly(alkyl methacrylate), a poly (tetrafluoroethylene), or mixtures thereof, wherein the alkyl groups of the poly(alkyl methacrylate) have one to about twelve carbon atoms.

3. The bulk light diffuser material as set forth in claim 2 wherein the poly(alkyl methacrylate) comprises poly(methyl methacrylate).

4. The bulk light diffuser material as set forth in claim 2, wherein the light diffusing particles comprise hydrolyzed poly(alkyl trialkoxysilanes), wherein the alkyl groups have one to about twelve carbon atoms.

5. The bulk light diffuser material as set forth in claim 1 wherein the light diffusing particles have a mean particle size of about 1.0 micrometer to about 10.0 micrometers.

6. The bulk light diffuser material as set forth in claim 1, wherein the light diffusing particles are present in an amount of about 2.2% to about 2.5% based on the total weight of the polycarbonate and the light diffusing particles.

7. The bulk light diffuser material as set forth in claim 1 wherein the bulk light diffuser material is in the form of a film or sheet.

8. The bulk light diffuser material as set forth in claim 7 wherein the film or sheet has a thickness of about 0.025 mm to about 0.5 mm.

9. The bulk light diffuser material as set forth in claim 1 wherein the light diffusing particles are matte surface poly(methyl methacrylate) particles that have a gloss value of less than about 50.

10. The bulk light diffuser material as set forth in claim 1 wherein the light diffusing particles are polished surface poly(methyl methacrylate) particles that have a gloss value of greater than about 90.

11. A backlight display device comprising:

an optical source for generating light;

a light guide for guiding the light therealong;

a reflective device positioned along the light guide for reflecting the light out of the light guide; and

a bulk light diffuser material receptive of the light from the light guide, the bulk light diffuser material comprising;

about 95 to about 99.8 percent by weight of a polycarbonate and about 0.2 to about 5 percent by weight of light diffusing particles, based on the total weight of the polycarbonate and of the light diffusing particles, wherein the light diffusing particles have a refractive index of 1.43 to 1.49; and

wherein the bulk light diffuser material has a percent transmittance of at least 70% and a haze of at least 10%.

12. The backlight display device as set forth in claim 11 wherein the light diffusing particles comprise a poly(alkyl methacrylate), a poly (tetrafluoroethylene), or mixtures thereof, wherein the alkyl groups of the poly(alkyl methacrylate) have one to about twelve carbon atoms.

13. The backlight display device as set forth in claim 12 wherein the poly(alkyl methacrylate) comprises poly(methyl methacrylate).

14. The backlight display device as set forth in claim 13 wherein poly(methyl methacrylate) particles are matte surface poly(methyl methacrylate) particles that have a gloss value of less than about 50.

15. The backlight display device as set forth in claim 13 wherein the poly(methyl methacrylate) particles are polished surface poly(methyl methacrylate) particles that have a gloss value of greater than about 90.

16. The backlight display device as set forth in claim 12 wherein the light diffusing particle comprises hydrolyzed poly(alkyl trialkoxysilanes), wherein the alkyl groups have one to about twelve carbon atoms.

17. The backlight display device as set forth in claim 11 wherein the light diffusing particles have a mean particle size of about 1.0 micrometer to about 10.0 micrometers.

18. The backlight display device as set forth in claim 11 wherein the light diffusing particles are present in an amount of about 2.2% to about 2.5% based on the total weight of polycarbonate and the light diffusing particles.

19. The backlight display device as set forth in claim 11 wherein the bulk light diffuser material is in the form of a film or sheet.

20. The backlight display device as set forth in claim 19 wherein the film or sheet has a thickness of about 0.025 mm to about 0.5 mm.

21. The backlight display device as set forth in claim 19 wherein the film or sheet includes a prismatic surface.

22. The backlight display device as set forth in claim 19 wherein the film or sheet includes a planar surface.

23. A bulk light diffuser material comprising:

about 95 to about 99.8 percent by weight of a polycarbonate and about 0.2 to about 5 percent by weight of light diffusing particles, based on the total weight of the polycarbonate and of the light diffusing particles, wherein the difference between the refractive index of the polycarbonate and the refractive index of the light diffusing particles is about 0.1 to about 0.16; and

wherein the bulk light diffuser material has a percent transmittance of at least 70% and a haze of at least 10%.

24. The bulk light diffuser material of claim 23 wherein the light diffusing particle comprises polymethyl methacrylate.

25. The bulk light diffuser material of claim 23 wherein the light diffusing particle comprises a hydrolyzed poly(alkyl trialkoxysilane), wherein the alkyl groups have one to about twelve carbon atoms.

26. A bulk light diffuser material comprising:

about 95 to about 99.8 percent by weight of a polycarbonate and about 0.2 to about 5 percent by weight of light diffusing particles, based on the total weight of the polycarbonate and of the light diffusing particles;

wherein the light diffusing particles comprise poly(methyl methacrylate), hydrolyzed poly(alkyl trialkoxysilane) or combinations thereof; and

wherein the bulk light diffuser material has a percent transmittance of at least 70% and a haze of at least 10%.

27. A backlight display device comprising:

an optical source for generating light;

a light guide for guiding the light therealong;

a reflective device positioned along the light guide for reflecting the light out of the light guide; and

a bulk light diffuser material receptive of the light from the light guide, the bulk light diffuser material comprising;

about 95 to about 99.8 percent by weight of a polycarbonate and about 0.2 to about 5 percent by weight of light diffusing particles, based on the total weight of the polycarbonate and of the light diffusing particles, wherein the difference between the refractive index of the polycarbonate and the refractive index of the light diffusing particles is about 0.1 to about 0.16; and

wherein the bulk light diffuser material has a percent transmittance of at least 70% and a haze of at least 10%.

28. The bulk light diffuser material of claim 27 wherein the light diffusing particle comprises polymethyl methacrylate.

29. The bulk light diffuser material of claim 27 wherein the light diffusing particle comprises a hydrolyzed poly(alkyl trialkoxysilane), wherein the alkyl groups have one to about twelve carbon atoms.

30. A backlight display device comprising:

an optical source for generating light;

a light guide for guiding the light therealong;

a reflective device positioned along the light guide for reflecting the light out of the light guide; and

a bulk light diffuser material receptive of the light from the light guide, the bulk light diffuser material comprising;

about 95 to about 99.8 percent by weight of a polycarbonate and about 0.2 to about 5 percent by weight of light diffusing particles, based on the total weight of the polycarbonate and of the light diffusing particles, wherein the light diffusing particles comprise poly(methyl methacrylate), hydrolyzed poly(alkyl trialkoxysilane) or combinations thereof; and

wherein the bulk light diffuser material has a percent transmittance of at least 70% and a haze of at least 10%.