Light diffuser with variable diffusion

• US 20030214812A1
• Filed: 05/16/2002
• Published: 11/20/2003
• Est. Priority Date: 05/16/2002
• Status: Active Grant

• Current Assignee: Rohm and Haas Denmark Finance A/S
• Original Assignee: Eastman Kodak Company
• Inventors: Bourdelais, Robert P., Kaminsky, Cheryl J.
• Granted Patent: US 6,846,098 B2
• Time in Patent Office: Days
• US Class Current: 362/330
• CPC Class Codes: G02B 5/0221 the surface having an irregular structure G02B5/0226 takes precedence
• CPC Class Codes: G02B 5/0242 by means of dispersed particles
• CPC Class Codes: G02B 5/0247 by means of voids or pores
• CPC Class Codes: G02B 5/0263 with positional variation of the diffusing properties, e.g. gradient or patterned diffuser
• CPC Class Codes: G02B 5/0278 used in transmission
• CPC Class Codes: G02F 1/133504 Diffusing, scattering, diffracting elements associated to illuminating devices G02F1/133606

Abstract

Disclosed is a light diffuser comprising a macro diffusion efficiency variation. Also disclosed is a light diffuser for rear projection displays, back-lighted imaging media, a liquid crystal display component and device, and a process for diffusing light.

Claims

1. A light diffuser comprising a macro diffusion efficiency variation.

2. The light diffuser of claim 1 wherein the diffusion efficiency varies by more than 10 percent in two different locations of the diffuser.

3. The light diffuser of claim 1 wherein the diffusion efficiency varies more than 50 percent in two different locations of the diffuser.

4. The light diffuser of claim 1 wherein the diffusion efficiency variation comprises a gradient.

5. The light diffuser of claim 1 that is rectangular in shape wherein there is diffusion efficiency variation along a diagonal of the rectangle.

6. The light diffuser of claim 1 that is rectangular in shape wherein there is diffusion efficiency variation along the width or height of the rectangle.

7. The light diffuser of claim 1 wherein there is diffusion efficiency variation from the geometric center to the perimeter of the diffuser.

8. The light diffuser of claim 1 wherein there is diffusion efficiency variation along the perimeter of the diffuser.

9. The light diffuser of claim 1 wherein the diffusion efficiency variation is such that iso-efficiency exhibits an elliptical pattern about the center of the diffuser.

10. The light diffuser of claim 1 wherein the diffusion efficiency variation comprises a repeating pattern.

11. The light diffuser of claim 1 wherein the diffusion efficiency variation comprises a specular component.

12. The light diffuser of claim 1 wherein the diffusion efficiency variation provides values at least 10% less in a perimeter area than in the center of said light diffuser.

13. The light diffuser of claim 1 further comprising a base and a plurality of convex or concave complex lenses on the surface of said base.

14. The plurality of complex lenses of claim 13 wherein the said convex or concave complex lenses are randomly distributed on the surface.

15. The plurality of complex lenses of claim 13 wherein the said convex or concave lenses are present on both the top and bottom surfaces of said transparent polymeric film.

16. The plurality of complex lenses of claim 13 wherein said concave or convex complex lenses have a average frequency in any direction of 5 to 250 complex lenses/mm.

17. The plurality of complex lenses of claim 13 wherein said concave or convex complex lenses have an average width in the x and y direction of 3 to 60 microns.

18. The plurality of complex lenses of claim 13 wherein said concave or convex complex lenses have a height/diameter ratio of 0.03 to 1.0.

19. The plurality of complex lenses of claim 13 wherein said concave or convex complex lenses comprise a multiple of minor lenses wherein the minor lenses have a width in the x and y direction of 2 to 20 microns.

21. The light diffuser of claim 1 further comprising a microvoided polymer sheet.

22. The light diffuser of claim 1 wherein said light diffuser comprises a surface diffuser.

23. The light diffuser of claim 1 wherein said light diffuser comprises a bulk diffuser.

27. The light diffuser of claim 1 wherein variable light diffusion efficiency is the result of differences in the composition of diffusion elements.

28. The light diffuser of claim 1 wherein variable light diffusion efficiency is the result of differences in surface microstructures.

29. A back lighted imaging media comprising a light source and the light diffuser of claim 1.

30. A liquid crystal device comprising a light source and the light diffuser of claim 1, wherein the light diffuser is located between the light source and a polarizing film.

31. A liquid crystal device component comprising a light source and the light diffuser of claim 1.

20. The transparent polymeric film of claim 20 wherein the number of minor lenses per major lens is 2 to 60.

24. A process for diffusing light comprising providing a light diffuser wherein the light diffusion efficiency is selectively modified.

26. The process of claim 26 wherein pressure is used to apply a gradient or pattern to the light diffuser.

25. The process of claim 26 wherein heat is used to apply a gradient or pattern to the light diffuser.