LIGHT CONTROL FILM

• US 20100271721A1
• Filed: 12/08/2008
• Published: 10/28/2010
• Est. Priority Date: 12/21/2007
• Status: Active Grant

• Current Assignee: 3M Innovative Properties Company (3M Company)
• Original Assignee: 3M Innovative Properties Company (3M Company)
• Inventors: Lauters, Michael E., Gaides, Gary E.
• Granted Patent: US 8,213,082 B2
• Time in Patent Office: Days
• US Class Current: 359/885
• CPC Class Codes: G02B 2207/123 Optical louvre elements, e.g. for directional light blocking
• CPC Class Codes: G02B 5/003 Light absorbing elements
• CPC Class Codes: G02B 5/045 Prism arrays
• CPC Class Codes: G02B 5/22 Absorbing filters G02B5/201 - G02B5/208 take precedence

Abstract

Provided is a light control film and displays incorporating same. In particular, provided are light control films comprising a light input surface and a light output surface opposite the light input surface. The light control films further comprise alternating transmissive and absorptive regions disposed between the light input surface and the light output surface. Each transmissive region has an index of refraction N1, and each absorptive region having an index of refraction N2, where N2−N1 is not less than −0.005. The light control films have an average pitch of successive absorptive regions of 0.070 mm or less. Light incident to the light input surface exits the light output surface with a maximum relative brightness ratio (RBR) in a direction perpendicular to the light output surface of 65 or greater, and exits the light output surface with an effective polar viewing angle (EPVA) of 45° or less.

Claims

1. A light control film, comprising:

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

alternating transmissive and absorptive regions disposed between the light input surface and the light output surface, each transmissive region having an index of refraction N1, and each absorptive region having an index of refraction N2, where N2−

N1 is not less than −

0.005;

wherein the average pitch of successive absorptive regions of 0.070 mm or less; and

wherein light incident to the light input surface exits the light output surface with a maximum relative brightness ratio (RBR) in a direction perpendicular to the light output surface of 65 or greater, and exits the light output surface with an effective polar viewing angle (EPVA) of 45°

or less.

2. The light control film of claim 1 wherein the EPVA is 40°

or less.

3. The light control film of claim 1 wherein the EPVA is 35°

or less.

4. The light control film of claim 1 wherein N2 equals N1.

5. The light control film of claim 1 wherein N2−

N1 is between −

0.005 and 0.02.

6. The light control film of claim 1 wherein each absorptive region comprises an optically absorptive material selected from a pigment, a dye, or a combination thereof.

7. The light control film of claim 6 wherein the optically absorptive material is a carbon black pigment.

8. The light control film of claim 1 wherein each of the transmissive and absorptive regions comprise a radiation cured (meth)acrylate polymer.

9. The light control film of claim 1 wherein the first interface between each transmissive and absorptive region forms a first interface angle θ

_I measured from a direction normal to the plane of the film, wherein first interface angle θ

_I is 6°

or less.

10. The light control film of claim 9 wherein first interface angle θ

_I is 4°

or less.

11. The light control film of claim 9 wherein the second interface between each transmissive and absorptive region forms a second interface angle θ

_I measured from a direction normal to the plane of the film, wherein the second interface angle θ

_I is 6°

or less.

12. The light control film of claim 11 wherein second interface angle θ

_I is 4°

or less.

13. The light control film of claim 11 wherein first interface angle θ

_I equals second interface angle θ

_I.

14. The light control film of claim 1 having an absorptive region width at its narrowest end of 12 μ

m or less.

15. The light control film of claim 1 having an absorptive region width at its narrowest end of 10 μ

m or less.

16. The light control film of claim 1 having an absorptive region width at its narrowest end of 8 μ

m or less.

17. The light control film of claim 1 having average pitch of successive absorptive regions of 0.065 mm or less.

18. The light control film of claim 1 having an MB20 of 60 or greater.