LIGHT CONTROL FILM WITH OFF-AXIS VISIBLE INDICIA

• US 20090284836A1
• Filed: 05/13/2009
• Published: 11/19/2009
• Est. Priority Date: 05/16/2008
• Status: Active Grant

• Current Assignee: 3M Innovative Properties Company (3M Company)
• Original Assignee: 3M Innovative Properties Company (3M Company)
• Inventors: Boyd, Gary T., Ehnes, Dale L., Pham, Tri D.
• Granted Patent: US 8,096,667 B2
• Time in Patent Office: Days
• US Class Current: 359/613
• CPC Class Codes: G02B 5/003 Light absorbing elements

Abstract

In one aspect, the invention provides a light control film having an indicium visible at a range of viewing angles. The light control film comprises a light input surface and a light output surface opposite the light input surface. The control film further comprises alternating transmissive and absorptive regions disposed between the light input surface and the light output surface. Each absorptive region has a height and a length, wherein the heights of the absorptive regions corresponding to the indicium are different that the heights of the absorptive regions that surround the absorptive regions corresponding to indicium.

Claims

1. A light control film having an indicium visible at a range of viewing angles, comprising:

a light input surface and a light output surface opposite the light input surface; and

alternating transmissive and absorptive regions disposed between the light input surface and the light output surface, each absorptive region having a height, wherein the heights of the absorptive regions corresponding to the indicium are different that the heights of the absorptive regions that surround the absorptive regions corresponding to indicium.

2. The light control film of claim 1 wherein the heights of the absorptive regions corresponding to the indicia are less than the heights of the absorptive regions that surround the regions corresponding to indicium.

3. The light control film of claim 1 wherein the heights of the absorptive regions corresponding to the indicia are greater than the heights of the absorptive regions that surround the regions corresponding to indicium.

4. The light control film of claim 2 wherein the heights of the absorptive regions corresponding to the indicium are varied.

5. The light control film of claim 1 wherein the absorptive regions have a length and the heights of the absorptive regions corresponding to the indicium vary along the length of such absorptive regions.

6. The light control film of claim 3 wherein the heights of the absorptive regions corresponding to the indicium are varied.

7. The light control film of claim 1 wherein absorptive regions have a trapezoidal shape.

8. The light control film of claim 1 wherein each transmission region has an index of refraction N1 and each absorptive region has an index of refraction N2, wherein N2−

N1 is not less than −

0.005.

9. The light control film of claim 7 wherein N2−

N1 is between −

0.005 and 0.02.

10. The light control film of claim 5 wherein the heights of the absorptive regions corresponding to the indicium vary along a portion of the length of such absorptive regions.

11. The light control film of claim 10 wherein the height of the absorptive regions corresponding to the indicium is zero height in the portion of the length.

12. The light control film of claim 2 wherein the heights of the absorptive regions corresponding to the indicia are zero height.

13. The light control film of claim 1 having at least first and second indicium.

14. The light control film of claim 13 wherein each of the absorptive regions corresponding to each of the at least first and second indicium have different heights.