Light reflector with variable diffuse light reflection

• US 6,898,012 B2
• Filed: 05/16/2002
• Issued: 05/24/2005
• Est. Priority Date: 05/16/2002
• Status: Expired due to Term

• Current Assignee: SKC Hi-Tech & Marketing Co., Ltd.
• Original Assignee: Eastman Kodak Company
• Inventors: Bourdelais, Robert P., Kaminsky, Cheryl J.
• Primary Examiner(s): Robinson, Mark A.
• Assistant Examiner(s): Fineman, Lee
• Application Number:
  US10/147,775
• Publication Number:
  US 20030214718A1
• Time in Patent Office: 1,104 Days
• Field of Search: 359/599, 359613-614, 359619-624, 359/626, 359454-456, 359/707, 349112-113, 349/62, 349/64, 349/67, 349/95, 362/31
• US Class Current: 359/599
• CPC Class Codes: G02B 5/0221 the surface having an irregular structure G02B5/0226 takes precedence
• CPC Class Codes: G02B 5/0247 by means of voids or pores
• CPC Class Codes: G02B 5/0278 used in transmission
• CPC Class Codes: G02B 5/0284 used in reflection
• CPC Class Codes: G02B 6/0041 provided in the bulk of the light guide
• CPC Class Codes: G02B 6/0055 Reflecting element, sheet or layer
• CPC Class Codes: G02B 6/0061 to provide homogeneous light output intensity
• CPC Class Codes: G02B 6/0065 Manufacturing aspects; Material aspects
• CPC Class Codes: G02F 1/133555 Transflectors
• CPC Class Codes: G02F 1/133615 Edge-illuminating devices, i.e. illuminating from the side

Abstract

Disclosed is a diffuse reflector comprising a macro reflection efficiency variation. The invention provides improved light reflection for a back lit display while simultaneously diffusely reflecting specular light sources.

Claims

1. A diffuse reflector polymeric film comprising a macro reflection efficiency variation that is greater than 5% over an in plane distance of at least 2 cm using an integrating sphere with a light entry port of 25.4 mm diameter, the reflector film having a reflectivity at 500 nanometers of greater than 50%.

2. The diffuse reflector of claim 1 wherein the reflection efficiency varies by more than 50 percent in two different locations of the diffuse reflector.

3. The diffuse reflector of claim 1 wherein the reflection efficiency variation comprises a gradient.

4. The diffuse reflector of claim 1 that is rectangular in shape wherein there is reflection efficiency variation along a diagonal of the rectangle.

5. The diffuse reflector of claim 1 that is rectangular in shape wherein there is reflection efficiency variation along the width or height of the rectangle.

6. The diffuse reflector of claim 1 wherein there is reflection efficiency variation from the center to the perimeter.

7. The diffuse reflector of claim 1 wherein there is a reflection efficiency variation along the perimeter.

8. The diffuse reflector of claim 1 wherein the reflection efficiency variation is such that iso-efficiency exhibits an elliptical pattern.

9. The diffuse reflector of claim 1 wherein the reflection efficiency variation comprises a repeating pattern.

10. The diffuse reflector of claim 1 wherein the reflection efficiency variation comprises a specular reflection component.

11. The diffuse reflector of claim 1 wherein the reflection efficiency variation provides values at least 10% less on the edges than in the center of said diffuse reflector.

12. The diffuse reflector of claim 1 wherein the diffuse reflector comprises at least one reflective layer and at least one film.

13. The diffuse reflector of claim 12 wherein the reflective layer is adhesively bonded to the film.

14. The diffuse reflector of claim 12 wherein the reflective layer is integral to the bottom surface of the film.

15. The diffuse reflector of claim 12 wherein the reflective layer is integral to the top surface of the film.

16. The diffuse reflector of claim 12 wherein the film is reflective.

17. The diffuse reflector of claim 12 wherein the reflective layer comprises a metal.

18. The diffuse reflector of claim 12 wherein the reflective layer comprises an alloy.

19. The diffuse reflector of claim 12 wherein the reflective layer comprises an oxide.

20. The diffuse reflector of claim 12 wherein the reflective layer comprises layers of polymer with differing indexes of refraction.

21. The diffuse reflector of claim 12 wherein the reflective layer comprises greater than 30 layers of polymer with differing indexes of refraction between at least two adjacent layers of 0.03 to 0.15.

22. The diffuse reflector of claim 12 wherein the reflective layer thickness is 0.5 nanometers to 50 micrometers.

23. The diffuse reflector of claim 12 wherein the reflective layer thickness is 0.25 to 50 nanometers.

24. The diffuse reflector of claim 12 wherein the reflective layer thickness is from 0.50 to 50.0 nanometers.

25. The diffuse reflector of claim 12 wherein the reflective layer has a reflectivity at 500 nanometers of greater than 50%.

26. The diffuse reflector of claim 12 wherein the reflective layer has a reflectivity at 500 nanometers of greater than 94%.

27. The diffuse reflector of claim 12 wherein the reflective layer has a resistivity of 0.03 to 1800 ohms per square.

28. The diffuse reflector of claim 1 further comprising a base and a plurality of convex or concave complex lenses on the surface of said base.

29. The diffuse reflector of claim 28 wherein the complex lenses are reflective.

30. The diffuse reflector of claim 28 wherein the said convex or concave complex lenses are randomly distributed on the surface.

31. The diffuse reflector of claim 28 wherein said concave or convex complex lenses have an average width in the x and y direction of 3 to 60 microns.

32. The diffuse reflector of claim 28 wherein said concave or convex complex lenses have a height/diameter ratio of 0.03 to 1.0.

33. The diffuse reflector of claim 28 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.

34. The diffuse reflector of claim 1 further comprising a microvoided polymer sheet.

35. The diffuse reflector of claim 34 wherein the microvoided polymer sheet comprises substantially circular voids.

36. The diffuse reflector of claim 1 wherein said diffuse reflector comprises a surface diffuser.

37. The diffuse reflector of claim 1 wherein said diffuse reflector comprises a bulk diffuser.

38. The diffuse reflector of claim 1 wherein said diffuse reflector comprises a base comprising a surface microstructure.

39. The diffuse reflector of claim 1 wherein said diffuse reflector comprises a colored element.

40. The diffuse reflector of claim 1 wherein said macro reflection efficiency variation comprises chromatic reflection.

41. A back lighted imaging media comprising a light source and a diffuse reflector comprising a macro reflection efficiency variation according to claim 1.

42. A liquid crystal device comprising a light source and a diffuse reflector comprising a macro reflection efficiency variation according to claim 1, wherein the diffuse reflector is located between the light source and a polarizing film.