Composite polymeric optical films with co-continuous phases

• US 20060193578A1
• Filed: 02/28/2005
• Published: 08/31/2006
• Est. Priority Date: 02/28/2005
• Status: Abandoned Application

• Current Assignee: 3M Innovative Properties Company (3M Company)
• Original Assignee: 3M Innovative Properties Company (3M Company)
• Inventors: Ouderkirk, Andrew J., Thunhorst, Kristin L., Fleming, Patrick R., Kopecky, William J., Benson, Olester Jr., North, Diane
• Application Number:
  US11/068,159
• Publication Number:
  US 20060193578A1
• Time in Patent Office: Days
• US Class Current: 385/115
• CPC Class Codes: B29C 48/022 characterised by the choice of material
• CPC Class Codes: B29C 48/05 Filamentary, e.g. strands
• CPC Class Codes: B29C 48/06 Rod-shaped
• CPC Class Codes: B29C 48/08 flexible, e.g. films
• CPC Class Codes: B29C 48/21 the layers being joined at their surfaces
• CPC Class Codes: B29C 48/307 specially adapted for bringing together components, e.g. melts within the die
• CPC Class Codes: B29C 70/14 oriented
• CPC Class Codes: B29K 2105/06 containing reinforcements, fillers or inserts
• CPC Class Codes: B29K 2995/0018 having particular optical properties, e.g. fluorescent or phosphorescent
• CPC Class Codes: G02B 5/0236 the diffusion taking place within the volume of the element
• CPC Class Codes: G02B 5/0257 creating an anisotropic diffusion characteristic, i.e. distributing output differently in two perpendicular axes
• CPC Class Codes: G02B 5/0268 characterized by the fabrication or manufacturing method
• CPC Class Codes: G02B 5/3008 comprising dielectric particles, e.g. birefringent crystals embedded in a matrix

Abstract

An optical element is formed by co-extruding to have an arrangement of polymer scattering fibers within a polymer matrix. The scattering fibers lie substantially parallel to a first axis. The scattering fibers are arranged at positions across the cross-section of the polymer matrix to scatter light transversely incident on the optical element in a direction substantially orthogonal to the first axis. The positions of the scattering fibers across the cross-section of the optical element may be selected so as to form a two-dimensional photonic crystal structure for light transversely incident on the optical element.

Claims

1. A method of forming an optical body, comprising:

coextruding polymer scattering fibers within a polymer matrix to form the optical body, the scattering fibers lying substantially parallel to a first axis, the scattering fibers being arranged at positions across a cross-section of the polymer matrix to scatter light transversely incident on the optical element in a direction substantially orthogonal to the first axis.

2. A method as recited in claim 1, wherein the scattering fibers are formed of a first polymer and the matrix is formed of a second polymer, at least one of the first and second polymers being birefringent, and further comprising orienting the birefringent at least one of the first and second polymers.

3. A method as recited in claim 2, wherein orienting comprises stretching the optical body along at least a first direction.

4. A method as recited in claim 3, further comprising allowing the optical body to relax in a direction orthogonal to the first direction while stretching the optical body along the first direction.

5. A method as recited in claim 1, wherein coextruding the scattering fibers comprises coextruding the scattering fibers containing a disperse phase of a first polymer within a continuous phase of a second polymer, at least one of the first and second polymers being birefringent, and further comprising orienting the birefringent at least one of the first and second polymers.

6. A method as recited in claim 1, further comprising forming at least a first scattering fiber to have a first cross-sectional dimension and at least a second scattering fiber to have a second cross-sectional dimension different from the first cross-sectional dimension.

7. A method as recited in claim 1, further comprising arranging the scattering fibers at locations on a regular grid.

8. A method as recited in claim 7, wherein arranging the scattering fibers comprises leaving some locations on the grid free of scattering fibers.

9. A method as recited in claim 1, further comprising arranging the scattering fibers across the cross-section of the matrix so as to form a photonic crystal structure for light transversely incident on the optical body in a direction orthogonal to the first axis.

10. A method as recited in claim 1, wherein at least some of the scattering fibers have a cross-sectional dimension in the range 50 nm-1000 nm.

11. A method as recited in claim 10, wherein at least some of the scattering fibers have a cross-sectional dimension in the range 100 nm-500 nm.

12. A method as recited in claim 1, further comprising forming at least some of the scattering fibers to have a circular cross-section.

13. A method as recited in claim 1, further comprising forming at least some of the scattering fibers to have a non-circular cross-section.

14. A method as recited in claim 13, wherein at least one of the scattering fibers having a non-circular cross-section has a longer cross-sectional direction that is parallel to a longer cross-sectional direction of another of the scattering fibers having a non-circular cross-section.

15. A method as recited in claim 13, wherein at least one of the scattering fibers having a non-circular cross-section has a longer cross-sectional direction that is non-parallel to a longer cross-sectional direction of another of the scattering fibers having a non-circular cross-section.

16. A method as recited in claim 1, further comprising forming at least a first of the scattering fibers to have a cross-sectional shape different from a cross-sectional shape of at least a second of the scattering fibers.

17. A method as recited in claim 1, further comprising forming at least one of the scattering fibers with a fiber shell surrounding a fiber core.

18. A method as recited in claim 1, further comprising forming flat major surfaces on the optical body.

19. A method as recited in claim 1, further comprising a structured surface on the optical body.

20. A method as recited in claim 19, wherein forming the structured surface comprises forming a surface that provides optical power to light passing through the structured surface.

21. A method as recited in claim 19, wherein forming the structured surface comprises forming a brightness enhancing surface.

22. A method as recited in claim 19, wherein scattering fibers are disposed within structure formed by the structured surface.

23. A method as recited in claim 1, wherein a total cross-sectional area of the scattering fibers comprises at least 1% of the cross-sectional area of the optical element.

24. A method as recited in claim 23, wherein the total cross-sectional area of the scattering fibers comprises at least 10% of the cross-sectional area of the optical element.

25. A method as recited in claim 1, wherein coextruding the scattering fibers comprises co-extruding the scattering fibers to produce a fill factor that is non-uniform across the optical body.

26. A method as recited in claim 1, further comprising varying a cross-sectional dimension along the length of at least one of the scattering fibers.

27. A method as recited in claim 26, further comprising varying the cross-sectional dimension of the at least one of the scattering fibers to a value equal to zero.

28. An optical body, comprising:

a polymer matrix; and

coextruded polymer scattering fibers within the polymer matrix, the scattering fibers lying substantially parallel to a first axis, the scattering fibers being arranged at positions across a cross-section of the polymer matrix to scatter light transversely incident on the optical element in a direction substantially orthogonal to the first axis.

29. A body as recited in claim 28, wherein the scattering fibers are formed of a first polymer and the matrix is formed of a second polymer, at least one of the first and second polymers being birefringent.

30. A body as recited in claim 28, wherein the scattering fibers comprise a disperse phase of a first polymer within a continuous phase of a second polymer, at least one of the first and second polymers being birefringent.

31. A body as recited in claim 28, wherein at least a first scattering fiber has a first cross-sectional dimension and a second scattering fiber has a second cross-sectional dimension different from the first cross-sectional dimension.

32. A body as recited in claim 28, wherein the scattering fibers are arranged at locations on a regular grid across a cross-section of the matrix.

33. A body as recited in claim 32, wherein some locations on the regular grid are free of scattering fibers.

34. A body as recited in claim 28, wherein the scattering fibers are arranged across the cross-section of the matrix so as to form a photonic crystal structure for light transversely incident on the optical body in a direction orthogonal to the first axis.

35. A body as recited in claim 28, wherein at least some of the scattering fibers have a cross-sectional dimension in the range 50 nm-1000 nm.

36. A body as recited in claim 28, wherein at least some of the scattering fibers have a cross-sectional dimension in the range 100 nm-500 nm.

37. A body as recited in claim 28, wherein at least a first of the scattering fibers has a cross-sectional shape different from a cross-sectional shape of at least a second of the scattering fibers.

38. A body as recited in claim 28, wherein at least one of the scattering fibers comprises a fiber shell surrounding a fiber core.

39. A body as recited in claim 28, wherein the polymer matrix comprises at least one flat major surface.

40. A body as recited in claim 28, wherein the polymer matrix comprises at least one structured surface.

41. A body as recited in claim 40, wherein the structured surface comprises a surface that provides optical power to light passing through the structured surface.

42. A body as recited in claim 40, wherein the structured surface comprises a brightness enhancing surface.

43. A body as recited in claim 28, wherein the total cross-sectional area of the scattering fibers comprises at least 10% of the cross-sectional area of the optical body.

44. A body as recited in claim 28, wherein a fill factor of the scattering fibers is non-uniform across a cross-setion of the optical body.

45. A body as recited in claim 28, wherein at least one of the scattering fibers has a cross-sectional dimension that is non-uniform along a length of the at least one of the scattering fibers.

46. A body as recited in claim 45, wherein the cross-sectional dimension of the at least one of the scattering fibers is zero at one location along the length of the at least one scattering fibers.