Optical assembly

• US 9,229,141 B2
• Filed: 12/13/2013
• Issued: 01/05/2016
• Est. Priority Date: 12/13/2012
• Status: Active Grant

• Current Assignee: 3M Innovative Properties Company (3M Company)
• Original Assignee: 3M Innovative Properties Company (3M Company)
• Inventors: Boyd, Gary T.
• Primary Examiner(s): Sugarman, Scott J
• Assistant Examiner(s): Betancourt, Alberto
• Application Number:
  US14/105,967
• Publication Number:
  US 20140168766A1
• Time in Patent Office: 753 Days
• Field of Search: 359/485.01
• US Class Current: 1/1
• CPC Class Codes: G02B 5/0231 the surface having microprismatic or micropyramidal shape macroscopic prism arrays G02B5/045
• CPC Class Codes: G02B 5/0236 the diffusion taking place within the volume of the element
• CPC Class Codes: G02B 5/30 Polarising elements light-modulating devices with active elements G02F1/00
• CPC Class Codes: G02B 5/3033 in the form of a thin sheet or foil, e.g. Polaroid

Abstract

An optical assembly includes a light directing film having an average effective transmission of at least 1.3, a light diffusing film having an optical haze of at least 5% and a plurality of spaced apart posts disposed and defining an air gap between the light directing and diffusing films. The posts are attached to a first major surface of the substrate and an opposing second end of each post is attached to the light diffusing film via a first adhesive layer. The first adhesive layer forms a meniscus at each post having an outer surface radius of at least 0.5 micrometers.

Claims

1. An optical assembly, comprising:

a light directing film having an average effective transmission of at least 1.3;

a light diffusing film having an optical haze of at least 5%; and

a plurality of spaced apart posts disposed and defining an air gap between the light directing and diffusing films, the plurality of spaced part posts being disposed on a first major surface of a substrate having an opposing second major surface, a first end of each post being attached to the first major surface of the substrate, an opposing second end of each post being attached to the light diffusing film via a first adhesive layer, the first adhesive layer forming a meniscus at each post, the meniscus having an outer surface radius of at least 0.5 micrometers;

wherein the plurality of spaced apart posts comprises a one dimensional array of spaced apart parallel linear posts, wherein for each linear post, a ratio of a length of the post to a width of the post is at least 10.

2. The optical assembly of claim 1, wherein the light directing film comprises a prism film comprising a plurality of linear prisms extending along a same direction.

3. The optical assembly of claim 1, wherein the light directing film comprises a reflective polarizer.

4. The optical assembly of claim 1, wherein the light directing film comprises a reflective polarizer and a prism film comprising a plurality of linear prisms extending along a same direction.

5. The optical assembly of claim 1, wherein the light directing film has an average effective transmission of at least 1.5.

6. The optical assembly of claim 1, wherein the light diffusing film comprises a surface diffuser.

7. The optical assembly of claim 1, wherein the light diffusing film comprises a volume diffuser.

8. The optical assembly of claim 1, wherein the light diffusing film comprises a symmetric diffuser that scatters light in a first direction with a first viewing angle A_H and in a second direction orthogonal to the first direction with a second viewing angle A_V substantially equal to A_H.

9. The optical assembly of claim 8, wherein a difference between A_V and A_H is less than 10 degrees.

10. The optical assembly of claim 1, wherein the light diffusing film comprises an asymmetric diffuser that scatters light in a first direction with a first viewing angle A_H and in a second direction orthogonal to the first direction with a second viewing angle A_V substantially different from A_H.

11. The optical assembly of claim 10, wherein a difference between A_V and A_H is greater than 15 degrees.

12. The optical assembly of claim 1, wherein the light diffusing film has an optical haze of at least 10%.

13. The optical assembly of claim 1, wherein a cross-section of each linear post in a direction perpendicular to the length of the post comprises a straight side edge.

14. The optical assembly of claim 1, wherein a cross-section of each linear post in a direction perpendicular to the length of the post comprises a curved side edge.

15. The optical assembly of claim 1, wherein a cross-section of each linear post in a direction perpendicular to the length of the post is a trapezoid.

16. The optical assembly of claim 1, wherein the air gap has an average height H_avg, each post having a maximum lateral width W_max, a minimum lateral width W_min and an average lateral width W_avg in the air gap, W_max/W_min being less than 5 H_avg/W_avg being at least 2.

17. The optical assembly of claim 1, wherein an average thickness of the first adhesive layer is less than 10 micrometers.

18. The optical assembly of claim 1, wherein the second major surface of the substrate is attached to the light directing film via a second adhesive layer.

19. An optical assembly, comprising:

a light directing film having an average effective transmission of at least 1.3;

a light diffusing film having an optical haze of at least 5%; and

a plurality of spaced apart posts disposed and defining an air gap between the light directing and diffusing films, the plurality of spaced part posts being disposed on a first major surface of a substrate having an opposing second major surface, a first end of each post being attached to the first major surface of the substrate, an opposing second end of each post being attached to the light diffusing film via a first adhesive layer, the first adhesive layer forming a meniscus at each post, the meniscus having an outer surface radius of at least 0.5 micrometers;

wherein the plurality of spaced apart posts comprises a two-dimensional array of posts, wherein for each post in the two-dimensional array of posts, a ratio of a height of the post to a width of the post is less than 100.

20. The optical assembly of claim 19, wherein at least some of the posts in the plurality of spaced apart posts comprise a piecewise planar facet.

21. The optical assembly of claim 19, wherein at least some of the posts in the plurality of spaced apart posts comprise a piecewise curved facet.