Light redirecting films and film systems

• US 20050122591A1
• Filed: 09/30/2004
• Published: 06/09/2005
• Est. Priority Date: 02/23/1999
• Status: Active Grant

• Current Assignee: Innovative Display Technologies LLC (Acacia Research Corporation)
• Original Assignee: Solid State Opto Limited (Global Lighting Technologies Inc.)
• Inventors: McCollum, Timothy A., Parker, Jeffery R.
• Granted Patent: US 7,364,341 B2
• Time in Patent Office: Days
• US Class Current: 359/619
• CPC Class Codes: F21V 5/002 using microoptical elements for redirecting or diffusing light
• CPC Class Codes: G02B 27/00 Optical systems or apparatus not provided for by any of the groups G02B1/00 - G02B26/00, G02B30/00
• CPC Class Codes: G02B 3/0043 Inhomogeneous or irregular arrays, e.g. varying shape, size, height
• CPC Class Codes: G02B 3/08 with discontinuous faces, e.g. Fresnel lens diffractive Fresnel lenses G02B5/1876
• CPC Class Codes: G02B 5/045 Prism arrays
• CPC Class Codes: G02B 6/0036 2-D arrangement of prisms, protrusions, indentations or roughened surfaces
• 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 6/0053 Prismatic sheet or layer; Brightness enhancement 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

Abstract

The light redirecting films of the present invention have a pattern of individual optical elements that may intersect and/or interlock each other to achieve substantially complete surface coverage of at least one of the surfaces occupied by the optical elements. At least some of the optical elements may have at least one flat surface and at least one curved surface that may intersect each other to a greater extent on the curved surface than on the flat surface to increase the relative percentage of flat surface area to curved surface area of the intersecting optical elements to increase the on axis gain of light passing through the film.

Claims

1. A light redirecting film comprising a thin optically transparent substrate having a light entrance surface for receiving light from a light source and an opposite light exit surface, at least one of the surfaces having a pattern of individual optical elements of well defined shape having at least one flat surface and at least one curved surface and being quite small relative to the length and width of the substrate to redistribute light passing through the substrate in a predetermined angular distribution, wherein at least some of the optical elements intersect each other.

2. The film of claim 1 wherein at least some of the optical elements intersect each other to a greater extent on the curved surface of the optical elements than on the flat surface to increase the relative percentage of flat surface area to curved surface area of the optical elements to increase on axis gain of light passing through the substrate.

3. The film of claim 2 wherein the relative percentage of the remaining flat surface area to the remaining curved surface area of the optical elements that intersect each other is greater than 60%.

4. The film of claim 2 wherein the relative percentage of the remaining flat surface area to the remaining curved surface area of the optical elements that intersect each other is greater than 75%.

5. The film of claim 1 wherein at least some of the optical elements intersect each other only on the curved surface of the optical elements to increase the relative percentage of flat surface area to curved surface area of the optical elements to increase on axis gain of light passing through the substrate.

6. The film of claim 1 wherein the predetermined angular distribution of the light passing through the substrate is in a direction more normal to the substrate.

7. The film of claim 1 wherein the predetermined angular distribution of the light passing through the substrate has a peak angular distribution that is normal to the substrate.

8. The film of claim 1 wherein the position or placement of the optical elements on at least one of the surfaces is randomized.

9. A light redirecting film comprising a thin optically transparent substrate having a light entrance surface for receiving light from a light source and an opposite light exit surface, at least one of the surfaces having a pattern of individual optical elements of well defined shape having at least two curved surfaces, one of the curved surfaces of the optical elements having a smaller radius than the other curved surface, the optical elements being quite small relative to the length and width of the substrate to redistribute light passing through the substrate in a predetermined angular distribution, wherein at least some of the optical elements intersect each other to a greater extent on the one curved surface of the optical elements than on the other curved surface to decrease the relative percentage of the one curved surface to the other curved surface of the optical elements to increase on axis gain of light passing through the substrate.

10. The film of claim 9 wherein the predetermined angular distribution of the light passing through the substrate is in a direction more normal to the substrate.

11. The film of claim 9 wherein the predetermined angular distribution of the light passing through the substrate has a peak angular distribution that is normal to the substrate.

12. A light redirecting film comprising a thin optically transparent substrate having a light entrance surface for receiving light from a light source and an opposite light exit surface, at least one of the surfaces having a pattern of individual optical elements of well defined shape having at least two sloping surfaces and being quite small relative to the length and width of the substrate to redistribute light passing through the substrate in a predetermined angular distribution, wherein at least some of the optical elements intersect each other to achieve substantially complete surface coverage of at least one of the surfaces of the substrate within the pattern of optical elements.

13. The film of claim 12 wherein at least one of the sloping surfaces is flat and at least one other of the sloping surfaces is curved.

14. The film of claim 12 wherein the surface coverage is greater than 90%.

15. The film of claim 12 wherein at least some of the optical elements also interlock each other to achieve substantially complete surface coverage of at least one of the surfaces of the substrate within the pattern of optical elements.

16. The film of claim 12 wherein the position or placement of the optical elements on at least one of the surfaces is randomized.

17. The film of claim 12 wherein the predetermined angular distribution of the light passing through the substrate is in a direction more normal to the substrate.

18. The film of claim 12 wherein the predetermined angular distribution of the light passing through the substrate has a peak angular distribution that is normal to the substrate.

19. A light redirecting film comprising a thin optically transparent substrate having a light entrance surface for receiving light from a light source and an opposite light exit surface, at least one of the surfaces having a pattern of individual optical elements of well defined shape having at least two sloping surfaces and being quite small relative to the length and width of the substrate to redistribute light passing through the substrate in a predetermined angular distribution, wherein at least some portion of the area of the one surface of the substrate, within the pattern of optical elements, has an area that is not completely covered by the optical elements leaving said area unpatterned.

20. The film of claim 19 wherein the percentage of unpatterned area is chosen to fit a particular application.

21. The film of claim 19 wherein the unpatterned area has one or more of an optically smooth finish, a surface treatment, a texture, or a coating.

22. The film of claim 19 wherein the position or placement of the optical elements on at least one of the surfaces is randomized.

23. The film of claim 19 wherein the predetermined angular distribution of the light passing through the substrate is in a direction more normal to the substrate.

24. The film of claim 19 wherein the predetermined angular distribution of the light passing through the substrate has a peak angular distribution that is normal to the substrate.

25. A light redirecting film comprising a thin optically transparent substrate having a light entrance surface for receiving light from a light source and an opposite light exit surface, at least one of the surfaces having a pattern of individual optical elements of well defined shape that are quite small relative to the length and width of the substrate to redistribute light passing through the substrate in a predetermined angular distribution, at least some of the optical elements being non-interlockable optical elements having a geometric shape that prevents the non-interlockable optical elements from interlocking with each other, the non-interlockable optical elements being oriented and placed to produce a desired coverage of the portion of at least one of the surfaces of the substrate within the pattern of non-interlockable optical elements.

26. The film of claim 25 wherein the coverage of the portion of at least one of the surfaces within the pattern of non-interlockable optical elements is substantially complete.

27. The film of claim 25 wherein the pattern of non-interlockable optical elements is comprised of at least two different shaped optical elements.

28. The film of claim 25 wherein at least some of the non-interlockable optical elements are positioned to intersect each other in order to increase the amount of coverage of the surface of the substrate within the pattern of non-interlockable optical elements.

29. The film of claim 25 wherein the non-interlockable optical elements have at least one curved surface and at least one flat surface, and at least some of the non-interlockable optical elements are positioned to intersect each other in order to increase the amount of coverage of the surface of the substrate within the pattern of non-interlockable optical elements.

30. The film of claim 29 wherein at least some of the non-interlockable optical elements are positioned to intersect each other to a greater extent on the curved surface than on the flat surface to increase the relative percentage of flat surface area to curved surface area of the non-interlockable optical elements to increase on axis gain of light passing through the substrate.

31. The film of claim 30 wherein the surface coverage is greater than 90%.

32. The film of claim 25 wherein the pattern of optical elements is on the light exit surface of the substrate.

33. The film of claim 25 wherein the pattern of optical elements is on the light entrance surface of the substrate.

34. The film of claim 25 wherein the predetermined angular distribution of the light passing through the substrate is in a direction more normal to the substrate.

35. The film of claim 25 wherein the light passing through the substrate has a peak angular distribution that is normal to the substrate.

36. The film of claim 25 wherein the percentage of uncovered area of the surface within the pattern of non-interlockable optical elements is chosen to fit a particular application.

37. The film of claim 25 wherein the uncovered area of the surface within the pattern of non-interlockable optical elements has one or more of an optically smooth finish, a surface treatment, a texture, or a coating.

38. The film of claim 25 wherein the position or placement of the non-interlockable optical elements on at least one of the surfaces is randomized.

39. A light redirecting film comprising a thin optically transparent substrate having a light entrance surface for receiving light from a light source, and an opposite light exit surface, at least one of the surfaces having a pattern of individual optical elements of well defined shape and quite small relative to the length and width of the substrate to redistribute light passing through the substrate in a predetermined angular distribution, at least some of said optical elements having at least two sides or surfaces that come together to form a ridge, said ridge having at least one section that is non-distinct or misshaped, wherein:

40. The film of claim 39 wherein the predetermined angular distribution of the light passing through the substrate is in a direction more normal to the substrate.

41. A light redirecting film comprising a thin optically transparent substrate having a light entrance surface for receiving light from a light source, and an opposite light exit surface, at least one of the surfaces having a pattern of individual optical elements of well defined shape and quite small relative to the length and width of the substrate to redistribute light passing through the substrate in a predetermined angular distribution, at least some of said optical elements having at least two sides or surfaces that come together to form a ridge, said ridge having at least one section that is non-distinct or misshaped, wherein:

42. The film of claim 41 wherein the predetermined angular distribution of the light passing through the substrate is in a direction more normal to the substrate.

43. A light redirecting film comprising a thin optically transparent substrate having a light entrance surface for receiving light from a light source, and an opposite light exit surface, at least one of the surfaces having a pattern of individual optical elements of well defined shape and quite small relative to the length and width of the substrate to redistribute light passing through the substrate in a predetermined angular distribution, said optical elements having only two sides or surfaces, one of the sides being flat and the other side being curved, the two sides coming together to form a ridge, said ridge having a flattened, rounded, curved or otherwise misshaped peak, wherein:

44. The film of claim 43 wherein the predetermined angular distribution of the light passing through the substrate is in a direction more normal to the substrate.