OPTICAL FILM HAVING A SURFACE WITH ROUNDED STRUCTURES

• US 20080266904A1
• Filed: 07/07/2008
• Published: 10/30/2008
• Est. Priority Date: 12/30/2004
• Status: Abandoned Application

• Current Assignee: 3M Innovative Properties Company (3M Company)
• Original Assignee: 3M Innovative Properties Company (3M Company)
• Inventors: Whitney, Leland R., Ko, Byung-Soo, Chae, Dongwon
• Application Number:
  US12/168,290
• Publication Number:
  US 20080266904A1
• Time in Patent Office: Days
• US Class Current: 362/619
• CPC Class Codes: G02B 6/0053 Prismatic sheet or layer; Brightness enhancement element, sheet or layer
• 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 devices including a light source and an optical film having a first surface disposed to receive light from the light source and a second surface facing away from the light source. The second surface includes a two-dimensional array of closely packed substantially hemispherically-shaped structures. In some implementations of the present disclosure, the optical film further includes a substrate portion having an optical characteristic different from optical characteristics of the second surface comprising the two dimensional array.

Claims

1. An optical device, comprising:

a light source;

a light gating device; and

a gain diffuser exhibiting an optical gain of at least about 1.2 and comprising a first surface receiving light from the light source and a second surface facing the light gating device and comprising a two-dimensional array of closely packed substantially hemispherically-shaped structures.

2. The optical device of claim 1, wherein the gain diffuser exhibits an optical gain of at least about 1.4.

3. The optical device of claim 1 further comprising at least one of a polarizer film, a diffuser film, a brightness enhancing film and a turning film.

4. The optical device of claim 3, wherein the polarizer film comprises a diffuse reflective polarizer film.

5. The optical device of claim 1, wherein a refractive index of the substantially hemispherically-shaped structures is lower than a refractive index of a layer in the gain diffuser.

6. A direct-lit backlight, comprising:

a light source;

a light gating device; and

a gain diffuser exhibiting an optical gain of at least about 1.2 and comprising a first surface facing the light source and a second surface facing the light gating device and comprising an array of structures, wherein an output light intensity distribution of the backlight has a primary, but not a secondary, peak.

7. The optical device of claim 6, wherein the gain diffuser exhibits an optical gain of at least about 1.4.

8. The direct-lit backlight of claim 6, wherein the output light intensity distribution has cylindrical symmetry.

9. The direct-lit backlight of claim 6, wherein the output light intensity distribution decreases monotonically from the primary peak.

10. The direct-lit backlight of claim 6, wherein the output light intensity distribution has a wider viewing angle relative to a viewing angle of the backlight absent the gain diffuser.

11. The direct-lit backlight of claim 6, wherein the array of structures comprises an array of substantially hemispherically-shaped structures.