LIGHT DIRECTING FILM

• US 20070279773A1
• Filed: 05/31/2006
• Published: 12/06/2007
• Est. Priority Date: 05/31/2006
• Status: Active Grant

• Current Assignee: 3M Innovative Properties Company (3M Company)
• Original Assignee: 3M Innovative Properties Company (3M Company)
• Inventors: Johnson, Todd M., Toma, Tetsuya, Marushin, Patrick H.
• Granted Patent: US 7,950,838 B2
• Time in Patent Office: Days
• US Class Current: 359/831
• 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: G02F 1/133504 Diffusing, scattering, diffracting elements associated to illuminating devices G02F1/133606

Abstract

A light directing film and an optical system incorporating same are disclosed. The light directing film includes a first major surface and a microstructured second major surface. The microstructured second major surface has at least two periodic microstructured patterns. The first periodic pattern is arranged along a first direction. The second periodic pattern is arranged along a second direction different from the first direction.

Claims

1. A light directing film, comprising:

a first major surface; and

a microstructured second major surface having at least two periodic microstructured patterns, a first of the at least two periodic microstructured patterns being arranged along a first direction with a first period, a second of the at least two periodic microstructured patterns being arranged along a second direction with a second period, the second direction being different from the first direction.

2. The light directing film of claim 1, wherein at least one microstructure in each of the first and second periodic patterns extends along a third direction, the third direction being different from the first and second directions.

3. The light directing film of claim 1, wherein all microstructures in the first and second periodic patterns extend along a third direction, the third direction being different from the first and second directions.

4. The light directing film of claim 1, wherein at least one microstructure in each of the first and second periodic patterns has a prismatic profile.

5. The light directing film of claim 1, wherein the second of the at least two periodic microstructured patterns forms a two-dimensional periodic pattern.

6. The light directing film of claim 1, wherein each microstructure in the first and second periodic microstructured patterns has a peak and a peak height measured from the peak to a common reference plane disposed between the first and second major surfaces, and wherein the height of at least one microstructure in the first periodic pattern is different from the height of at least one microstructure in the second periodic pattern.

7. The light directing film of claim 1, further comprising a third of the at least two periodic microstructured patterns arranged along a third direction with a third period, the third direction being different from the first and second directions.

8. A light guide assembly for use in a liquid crystal display, the light guide assembly comprising at least one light directing film of claim 1.

9. A light directing film comprising a first major surface and a second major surface, the second major surface having a two-dimensional microstructured pattern superimposed on a one-dimensional periodic microstructured pattern.

10. The light directing film of claim 9, wherein the two-dimensional microstructured pattern is periodic along at least one direction.

11. The light directing film of claim 9, wherein the two-dimensional microstructured pattern is periodic along at least two different directions.

12. The light directing film of claim 9, wherein each microstructure in the one-dimensional and two-dimensional patterns has a peak and a peak height measured from the peak to a common reference plane disposed between the first and second major surfaces, and wherein the heights of the microstructures in the one-dimensional periodic microstructured pattern are different than the heights of the microstructures in the two-dimensional microstructured pattern.

13. The light directing film of claim 12, wherein at least two microstructures in the two-dimensional microstructured pattern have different heights.

14. The light directing film of claim 9, wherein at least two microstructures in the two-dimensional microstructured pattern have different shapes.

15. The light directing film of claim 9, wherein the microstructures in the one- and two-dimensional patterns extend along a same direction.

16. The light directing film of claim 9, wherein at least some of the microstructures in the one- and two-dimensional patterns are prismatic.

17. A light guide assembly for use in a liquid crystal display, the light guide assembly comprising at least one light directing film of claim 9.

18. A light directing film comprising a first major surface and a second major surface, the second major surface having a two-dimensional regularly-spaced pattern of discrete elements disposed on a one-dimensional periodic microstructured pattern.

19. The light directing film of claim 18, wherein at least some of the discrete elements are microstructured.