Optical film

• US 7,891,856 B2
• Filed: 08/24/2007
• Issued: 02/22/2011
• Est. Priority Date: 08/28/2006
• Status: Active Grant

• Current Assignee: Eternal Materials Co., Ltd.
• Original Assignee: Eternal Chemical Company Limited
• Inventors: Chuang, Shih-Yi, Wu, Guo-Long
• Primary Examiner(s): Lee; Jong-Suk (James)
• Assistant Examiner(s): Crowe; David R
• Application Number:
  US11/895,499
• Publication Number:
  US 20080055937A1
• Time in Patent Office: 1,278 Days
• Field of Search: 362/606, 362/627, 362/330, 362/339, 349/62, 359/599, 359/619, 385/129, 385/130, 385/146
• US Class Current: 362/627
• CPC Class Codes: G02B 5/045 Prism arrays
• CPC Class Codes: G02B 6/0053 Prismatic sheet or layer; Brightness enhancement element, sheet or layer

Abstract

The subject invention provides an optical film comprising a transparent substrate and a structured surface layer, wherein the structured layer is positioned on the upper surface of the substrate and comprises a plurality of non-parallel, adjacent columnar structures. The optical film according to the subject invention can effectively enhance the brightness of a liquid crystal display and reduce the optical interference.

Claims

1. An optical film, comprising:

a plastic substrate, and

a structured surface layer, positioned on one side of the substrate,

wherein the structured surface layer has an irregular brightness enhancing structure that comprises a plurality of non-parallel, adjacent columnar structures, wherein the plurality of non-parallel, adjacent columnar structures a set of two non-parallel, crossed columnar structures and a set of two non-parallel, non-crossed columnar structures.

2. The optical film as claimed in claim 1, wherein the columnar structures are selected from the group consisting of prismatic columns, arc columns and a combination thereof .

3. The optical film as claimed in claim 1, wherein the columnar structures are prism columns.

4. The optical film as claimed in claim 3, wherein the prism columns have an apex angle in a range from 50°

to 120°

.

5. The optical film as claimed in claim 4, wherein the apex angle of the prism columns is in a range from 85°

to 95°

.

6. The optical film as claimed in claim 1, wherein the columnar structures are arc columns.

7. The optical film as claimed in claim 1, wherein the columnar structures comprise a combination of prism columns and arc columns.

8. The optical film as claimed in claim 1, wherein the plurality of non-parallel, adjacent columnar structures are linear.

9. The optical film according to claim 1, wherein the structured surface layer is produced by forming a colloidal coating layer on the plastic substrate and then roller embossing with a roller having grooves that form said structured surface layer with said plurality of non-parallel, adjacent columnar structures.

10. An optical film, comprising:

a polyester resin substrate, and

a structured surface layer, positioned on the upper surface of the substrate,

wherein the structured surface layer has an irregular brightness enhancing structure that comprises a plurality of non-parallel, adjacent linear prism columnar structures, wherein the plurality of non-parallel, adjacent linear prism columnar structures comprise a set of two non-parallel crossed linear prism columnar structures and a set of two non-parallel, non-crossed linear prism columnar structures, the width of the columnar structures is in a range from 1 μ

m to 100 μ

m, and the optical film has a refractive index of at least 1.50.

11. The optical film as claimed in claim 10, wherein the structured surface layer further comprises a set of two columnar structures parallel to each other.

12. The optical film as claimed in claim 10, wherein the prism columnar structures have an apex angle in a range from 50°

to 120°

.

13. The optical film as claimed in claim 12, wherein the apex angle of the prism columnar structures is in a range from 85°

to 95°

.

14. The optical film as claimed in claim 10, wherein the structured surface layer is composed of a (meth)acrylate resin.

15. The optical film as claimed in claim 10, wherein the lower surface of the substrate is smooth.

16. The optical film as claimed in claim 10, wherein the lower surface of the substrate is unsmooth.

17. The optical film according to claim 10, wherein the structured surface layer is produced by forming a colloidal coating layer on the plastic substrate and then roller embossing with a roller having grooves that form said structured surface layer with said plurality of non-parallel, adjacent linear prism columnar structures.

18. A liquid crystal display, comprising:

a surface light source device; and

an optical film disposed above the light-out plane of the surface light source device,

wherein the optical film has a structured surface layer, and the structured surface layer has an irregular brightness enhancing structure that comprises a plurality of non-parallel, adjacent columnar structures, wherein the plurality of non-parallel, adjacent columnar structures comprise a set of two non-parallel, crossed linear prism columnar structures and a set of two non-parallel, non-crossed linear prism columnar structures.

19. The liquid crystal display according to claim 18, wherein the structured surface layer is produced by forming a colloidal coating layer on the plastic substrate and then roller embossing with a roller having grooves that form said structured surface layer with said plurality of non-parallel, adjacent columnar structures.