Optical film having a structured surface with offset prismatic structures

• US 7,220,026 B2
• Filed: 12/30/2004
• Issued: 05/22/2007
• Est. Priority Date: 12/30/2004
• Status: Expired due to Fees

• Current Assignee: 3M Innovative Properties Company (3M Company)
• Original Assignee: 3M Innovative Properties Company (3M Company)
• Inventors: Gardiner, Mark E., Ko, Byung-Soo, Chae, Dongwon
• Primary Examiner(s): Tso; Laura K.
• Application Number:
  US11/026,938
• Publication Number:
  US 20060152943A1
• Time in Patent Office: 873 Days
• Field of Search: 362/339, 362/330, 362/620
• US Class Current: 362/339
• 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 6/0056 for producing polarisation effects, e.g. by a surface with polarizing properties or by an additional polarizing elements

Abstract

The present disclosure is directed to optical films having a first surface and a structured surface, the structured surface comprising a plurality of prismatic structures. Each prismatic structure has a base including at least two first sides and at least two second sides. At least one of the first and second sides of at least one of the plurality of prismatic structures is offset with respect to at least one of the first and second sides of at least one other prismatic structure.

Claims

1. An optical film having a first surface and a structured surface, the structured surface comprising a plurality of prismatic structures, each structure having a base including at least two first sides and at least two second sides, a first side having a different length than a second side, wherein each of the plurality of prismatic structures comprises five substantially planar surfaces, four surfaces being attached to the base, each of the four surfaces positioned to angle in from the base toward the fifth surface;

wherein at least one of the first and second sides of at least one of the plurality of prismatic structures is offset with respect to at least one of the first and second sides of at least one other prismatic structure; and

wherein light enters the optical film through either the surface or the structured surface.

2. The optical film as recited in claim 1, wherein the two first sides are disposed opposite to each other along a first general direction and the two second sides are disposed opposite to each other along a second general direction,

wherein the optical film transmits a substantial portion of light incident on the first surface along the first general direction when an angle of incidence is within a first angle with respect to an axis disposed at an angle to the first surface and reflects a substantial portion of light when the angle of incidence is outside the first angle, and

wherein the optical film transmits a substantial portion of light incident on the first surface along the second general direction when an angle of incidence is within a second angle with respect to the axis and reflects a substantial portion of light when the angle of in incidence is outside the second angle.

3. The optical film as recited in claim 2, wherein the axis is generally orthogonal to the first surface.

4. The optical film according to claim 2, wherein the first angle is different from the second angle.

5. The optical film according to claim 1, wherein the base has a generally rectangular shape.

6. The optical film according to claim 1, wherein each of the plurality of prismatic structures is further characterized by an apex angle that lies within a range of about 60 degrees to about 120 degrees.

7. The optical film according to claim 1, wherein each of the plurality of prismatic structures is arranged in contact with at least one other prismatic structure.

8. The optical film according to claim 1, wherein the optical film further comprises a substrate portion having an additional optical characteristic different from an optical characteristic of the structured surface.

9. The optical film according to claim 8, wherein the substrate portion comprises at least one of:

a polarizer, a diffuser, a brightness enhancing film, a turning film and any combination thereof.

10. An optical device comprising a light source and the optical film of claim 1 disposed so that the structured surface faces away from the light source.

11. The optical device of claim 10, further comprising a lightguide disposed between the light source and the optical film.

12. The optical device according to claim 10, further comprising a light valve arrangement disposed to receive light transmitted through the optical film.

13. An optical film having a first surface and a structured surface, the structured surface comprising a plurality of prismatic structures, each structure having a base including at least two first sides and at least two second sides, a first side having a different length than a second side, wherein each of the plurality of prismatic structures comprises five substantially planar surfaces, four surfaces being attached to the base, each of the four surfaces positioned to angle in from the base toward the fifth surface;

wherein at least one of the first and second sides of at least one of the plurality of prismatic structures is transversely offset with respect to at least one of the first and second sides of at least one other prismatic structure; and

wherein light enter the optical film through either the first surface or the structured surface.

14. The optical film according to claim 13, wherein the base has a generally rectangular shape.

15. The optical film according to claim 13, wherein the bases of the plurality of prismatic structures are disposed so that the first and second sides are substantially parallel to one another.

16. The optical film according to claim 13, wherein the optical film further comprises a substrate portion having an additional optical characteristic different from an optical characteristic of the structured surface.

17. The optical film according to claim 13, wherein the first and second sides of at least one of the plurality of prismatic structures are transversely offset with respect to at least one of the first and second sides of at least one other prismatic structure by first and second distances respectively.

18. The optical film according to claim 17, wherein the first distance is different from the second distance.

19. An optical film having a first surface and a structured surface, the structured surface comprising a plurality of prismatic structures, each structure having a base including at least two first sides and at least two second sides, a first side having a different length than a second sides, wherein each of the plurality of prismatic structures comprises five substantially planar surfaces, four surfaces being attached to the base, each of the four surfaces positioned to angle in from the base toward the fifth surface;

wherein at least one of the first and second sides of at least one of the plurality of prismatic structures is angularly offset with respect to at least one of the first and second sides of at least one other prismatic structure; and

wherein light enters the optical film through either the first surface or the structured surface.

20. The optical device according to claim 19 wherein the base has a generally rectangular shape.

21. The optical film according to claim 19, wherein the bases of the plurality of prismatic structures are disposed so that the angular offset varies across the structured surface.

22. The optical film according to claim 19, wherein the optical film further comprises a substrate portion having an additional optical characteristic different from an optical characteristic of the structured surface.