Method for stacking surface structured optical films

• US 6,846,089 B2
• Filed: 05/16/2003
• Issued: 01/25/2005
• Est. Priority Date: 05/16/2003
• Status: Active Grant

• Current Assignee: 3M Innovative Properties Company (3M Company)
• Original Assignee: 3M Innovative Properties Company (3M Company)
• Inventors: Bianconi, Joseph J., Stevenson, James A.
• Primary Examiner(s): Sember, Thomas M.
• Assistant Examiner(s): TRUONG, BAO Q
• Application Number:
  US10/439,450
• Publication Number:
  US 20040228106A1
• Time in Patent Office: 620 Days
• Field of Search: 362/31, 362/26, 362/27, 362/559, 362/560, 362/561, 362/19, 349/61, 349/62, 349/63, 349/64, 349/65
• US Class Current: 362/627
• CPC Class Codes: G02B 5/045 Prism arrays
• CPC Class Codes: G02B 6/0053 Prismatic sheet or layer; Brightness enhancement element, sheet or layer
• CPC Class Codes: G02B 6/0065 Manufacturing aspects; Material aspects
• CPC Class Codes: G02F 1/133606 including a specially adapted diffusing, scattering or light controlling members
• CPC Class Codes: G02F 1/133607 the light controlling member including light directing or refracting elements, e.g. prisms or lenses
• CPC Class Codes: G02F 2202/28 Adhesive materials or arrangements

Abstract

A display includes an optical film that has a surface structure, such as a prismatically structured surface for increasing the brightness of the display. The structured surface is bonded to an opposing surface of a second film using a layer of adhesive, by penetrating the structured surface into the adhesive layer to a depth less than a feature height of the structured surface. The bonded film structure provides additional strength to the films and reduces the possibility of film damage during display assembly.

Claims

1. A light management film package for managing light within a display, comprising:

a first, brightness enhancing optical film having a first surface structured with prismatic ribs, the ribs having associated rib heights;

a second optical film having a second surface opposing the first surface of the first optical film; and

a first layer of adhesive on the second surface, at least some of the prismatic ribs of the first surface penetrating into the first layer of adhesive, the first layer of adhesive having a thickness less than the associated rib heights of the ribs penetrating into the first adhesive layer.

2. A film package as recited in claim 1, wherein at least one of the prismatic ribs has a symmetrical cross-section.

3. A film package as recited in claim 1, wherein the second optical film is a prismatic brightness enhancing film having a non-ribbed surface oriented towards the First optical film and a prismatically structured surface with light-directing, ribbed prisms on a surface directed away from the first optical film.

4. A film package as recited in claim 3, wherein the light directing, ribbed prisms on the second surface of the second film are oriented substantially perpendicular to the prismatic ribs of the first film.

5. A film package as recited in claim 1, wherein the second optical film further includes a second structured surface, the second structured surface including structure features with associated feature heights, and further comprising a third optical film having a third surface and a second layer of adhesive on the third surface, at least some of the structure features of the second structured surface of the penetrating into the second layer of adhesive.

6. A film package as recited in claim 5, wherein the second layer of adhesive has a thickness less than the feature heights of the structure features penetrating into the second adhesive layer.

8. A film package as recited in claim 1, wherein a penetration depth of the structure features penetrating into the first adhesive layer is less than one half of the feature height of the features penetrating into the first adhesive layer.

9. A film package as recited in claim 8, wherein a penetration depth of the structure features penetrating into the first adhesive layer is less than one fifth of the feature height of the features penetrating into the first adhesive layer.

10. A film package as recited in claim 1, wherein the first layer of adhesive has a thickness of less than 5 μ

m.

11. A film package as recited in claim 1, wherein the second surface of the second film opposing the first surface of the first film is an anti-wet-out surface.

12. A film package as recited in claim 1, wherein the second optical film is a reflective polarizer.

13. A film package as recited in claim 12, further comprising a diffusing layer disposed on a side of the reflective polarizer facing away from the first optical film.

14. A film package as recited in claim 12, wherein the reflective polarizer and the first, brightness enhancing optical film together form a bonded combination and further comprising a support sheet on at least one side of the bonded combination.

15. A film package as recited in claim 12, further comprising a diffusion plate disposed to a second side of the first optical film opposite the first surface.

16. A film package as recited in claim 15, further comprising a structured layer of adhesive disposed between the first optical film and the diffusion plate so as to provide at least one air gap between the first optical film and the diffusion plate.

7. A film package as recited in claim wherein the first and second optical films are prismatic, light directing films, and the third optical film is a reflecting polarizer.

17. A display system, comprising:

an illumination unit;

a display unit; and

a light management unit disposed between the illumination unit and the display unit to manage light passing from the illumination unit source to the display unit, the light management unit comprising a first optical film having a first surface structured with prismatic ribs, the ribs having associated rib heights, a second optical film having a second surface opposing the first surface of the first optical film, and a first layer of adhesive on the second surface, at least some of the prismatic ribs of the first surface penetrating into the first layer of adhesive, the lirst layer of adhesive having a thickness less than the associated rib heights of the ribs penetrating into the first adhesive layer.

18. A system as recited in claim 17, further comprising a control unit coupled to the display unit to control an image displayed by the display unit.

19. A system as recited in claim 17, wherein the display unit includes a liquid crystal display layer.

20. A system as recited in claim 19, further comprising an absorbing polarizer layer on a viewing side of the liquid crystal display layers and an absorbing polarizer on a light source side of the liquid crystal display layer.

21. A system as recited in claim 17, wherein the illumination unit includes one or more light sources illuminating a light guide panel, light from the one or more light sources entering the light guide panel and passing through a side wall of the light guide panel to the light management unit.

22. A system as recited in claim 17, further comprising a frame holding the illumination unit, the light management unit and the display unit.

23. A system as recited in claim 22, wherein at least the lirst and second optical films of the light management unit include one or more peripheral alignment tabs for locating the light management unit within the frame.

24. A light management film package for managing light within a display, comprising:

a first optical film having a first surface structured with refractive features, the refractive features including active refractive surfaces for light to pass therethrough; and

a second optical film disposed over the first optical film, the second optical film having a second surface; and

a first layer of adhesive on the second surface, at least some of the refractive features penetrating partially into the first layer of adhesive so as to leave a gap between the first adhesive layer and portions of the first surface, portions of the active surfaces of the penetrating features interfacing with the gap and other portions of the penetrating features interfacing with the first adhesive layer.

25. A film package as recited in claim 24, wherein the first surface is structured with prismatic ribs.

26. A film package as recited in claim 25, wherein at least one of the prismatic ribs has a symmetrical cross-section.

27. A film package as recited in claim 24, wherein the second optical film is a prismatic, light-directing film having a non-ribbed surface oriented towards the first optical film and a surface having prismatic ribs being directed away from the first optical film.

28. A film package as recited in claim 27, wherein the first surface is structured with prismatic ribs and the prismatic ribs on the second filrn are oriented perpendicular to the prismatic-ribs of the first film.

29. A film package as recited in claim 27, further comprising a third optical film having a third surface and a second layer of adhesive on the third surface, at least some of the prismatic ribs of the second optical film penetrating into the second layer of adhesive.

30. A film package as recited in claim 29, wherein the third optical film is a reflecting polarizer.

31. A film package as recited in claim 24, wherein a penetration depth of the refractive features penetrating into the first adhesive layer is less than one half of the feature height of the refractive features penetrating into the first adhesive layer.

32. A film package as recited in claim 24, wherein the second surface of the second film opposing the first surface of the first film is an anti-wet-out surface.

33. A film package as recited in claim 24, wherein the thickness of the first adhesive layer and a penetration depth of the first structured surface into the first adhesive layer are selected so that characteristics of light passing through the film package are different from characteristics of light passing through a stack of the first and second optical films without an adhesive layer.

34. A film package as recited in claim 24, wherein the second optical film is a reflective polarizer.

35. A film package as recited in claim 34, further a diffusing layer disposed on a side of the reflective polarizer facing away from the first optical film.

36. A film package as recited in claim 34, wherein the reflective polarizer and the first optical film together form a bonded combination and further comprising a support sheet on at least one side of the bonded combination.

37. A film package as recited in claim 34, further comprising a diffusion plate disposed to a second side of the first optical film opposite the first surface.

38. A film package as recited in claim 37, further comprising a structured layer of adhesive disposed between the first optical film and the diffusion plate so as to provide at least one air gap between the first optical film and the diffusion plate.

39. A display system, comprising:

an illumination unit;

a display unit; and

a light management unit disposed between the illuminaltion unit and the display unit to manage light passing from the illumination unit source to the display unit, the light management unit cornprising a first optical film having a first surface structured with refractive features, the refractive features including active refractive surfaces for light to pass therethrough, a second optical film disposed over the first optical film, the second optical film having a second surface and a first layer of adhesive on the second surface, at least some of the refractive features penetrating partially into the first layer of adhesive so as to leave a gap between the first adhesive layer and portions of tho first surface, portions of the active surfaces of the penetrating features interlacing with the gap and other portions of the penetrating features intergacing with the first adhesive layer.

40. A system as recited in claim 39, further comprising a control unit coupled to the display unit to control an image displayed by the display unit.

41. A system as recited in claim 39, wherein the display unit includes a liquid crystal display layer.

42. A system as recited in claim 41, further comprising an absorbing polarizer layer on a viewing side of the liquid crystal display layers and an absorbing polarizer on a light source side of the liquid crystal display layer.

43. A system as recited in claim 39, wherein the illumination unit includes one or more light sources illuminating a light guide panel, light from the one or more light sources entering the fight guide panel and passing through a side wall of the light guide panel to the light management unit.

44. A system as recited in claim 39, lurthercomprising a frame holding the illumination unit, the light management unit and the display unit.

45. A system as recited in claim 44, wherein at least the first and second optical films of the light management unit include one or more peripheral alignment tabs for locating the fight management unit within the frame.