Brightness enhancing film and display device having the same

• US 7,586,566 B2
• Filed: 05/16/2006
• Issued: 09/08/2009
• Est. Priority Date: 06/03/2005
• Status: Active Grant

• Current Assignee: 3M Innovative Properties Company (3M Company)
• Original Assignee: 3M Innovative Properties Company (3M Company)
• Inventors: Nelson, Eric W., Zhang, Wei Feng
• Primary Examiner(s): Nelms; David
• Assistant Examiner(s): Chung; David Y
• Application Number:
  US11/383,690
• Publication Number:
  US 20060274237A1
• Time in Patent Office: 1,211 Days
• Field of Search: 349/112, 349/64
• US Class Current: 349/112
• CPC Class Codes: G02B 5/045 Prism arrays
• CPC Class Codes: G02B 5/208 for use with infrared or ultraviolet radiation, e.g. for separating visible light from infrared and/or ultraviolet radiation
• CPC Class Codes: G02F 1/133606 including a specially adapted diffusing, scattering or light controlling members
• CPC Class Codes: G02F 1/133607 the light controlling member including light directing or refracting elements, e.g. prisms or lenses
• CPC Class Codes: G02F 1/133611 including means for improving the brightness uniformity

Abstract

A brightness enhancing film suitable for use in a display device is disclosed herein. The film comprises: a first polymeric layer having a microstructured surface, wherein the microstructured surface comprises an array of prism elements, and a second polymeric layer disposed adjacent to the first polymeric layer on the opposite side of the microstructured surface, wherein at least one of the first and second polymeric layers comprises a UV absorber that absorbs UV light and transmits visible light, such that the brightness enhancing film has an internal percent transmission of at least 95% at 410 nm, and at most 25% at 380 nm. Also disclosed herein is a brightness enhancing film wherein the UV absorber is in a third layer disposed between the first and second layers. The brightness enhancing films disclosed herein may be used in display devices such as LCD-TVs.

Claims

1. A brightness enhancing film suitable for use in a display device, the film comprising:

a first polymeric layer having a microstructured surface, wherein the microstructured surface comprises an array of prism elements, and

a second polymeric layer disposed adjacent to the first polymeric layer on the opposite side of the microstructured surface,

wherein at least one of the first and second polymeric layers comprises a UV absorber that absorbs UV light and transmits visible light, such that the brightness enhancing film has an internal percent transmission of at least 95% at 410 nm, and at most 25% at 380 nm.

2. The brightness enhancing film of claim 1, wherein the first polymeric layer comprises the UV absorber and the second polymeric layer does not.

3. The brightness enhancing film of claim 1, wherein the second polymeric layer comprises the UV absorber and the first polymeric layer does not.

4. The brightness enhancing film of claim 1, wherein the first and second polymeric layers each comprise the UV absorber.

5. The brightness enhancing film of claim 1, wherein b* is about 2.5 or less.

6. The brightness enhancing film of claim 1, wherein the internal percent transmission at 380 nm is at most 15%.

7. The brightness enhancing film of claim 1, wherein the film exhibits Δ

b* of at most 4 after exposure to irradiation at 380 nm at an intensity 5 to 10 mW/cm² for 200 hours and 65°

C.

8. The brightness enhancing film of claim 1, wherein the UV absorber is a benzotriazole, benzatriazine, benzophenone, or a combination thereof.

16. A display device comprising:

a display panel;

a light source;

a reflective polarizer disposed between the display panel and the light source;

the brightness enhancing film of claim 1 disposed between the reflective polarizer and the light source, the first polymeric layer opposite the reflective polarizer; and

wherein the light source illuminates the display panel through the brightness enhancing film and the reflective polarizer.

17. The display device of claim 16, wherein the display panel is a liquid crystal display panel.

18. The display device of claim 16, wherein the display device is a television.

9. A brightness enhancing film suitable for use in a display device, the film comprising:

a first polymeric layer having a microstructured surface, wherein the microstructured surface comprises an array of prism elements,

a second polymeric layer disposed adjacent to the first polymeric layer on the opposite side of the microstructured surface, and

a third layer disposed between the first and second polymeric layers,

wherein the third layer comprises a UV absorber that absorbs UV light and transmits visible light, such that the brightness enhancing film has an internal percent transmission of at least 95% at 410 nm, and at most 25% at 380 nm.

10. The brightness enhancing film of claim 9, wherein the first and second polymeric layers do not comprise a UV absorber.

11. The brightness enhancing film of claim 9, wherein the first and/or second polymeric layers comprise a UV absorber.

12. The brightness enhancing film of claim 9, wherein b* is about 2.5 or less.

13. The brightness enhancing film of claim 9, wherein the internal percent transmission at 380 nm is at most 15%.

14. The brightness enhancing film of claim 9, wherein the film exhibits Δ

b* of at most 4 after exposure to irradiation at 380 nm at an intensity 5 to 10 mW/cm² for 200 hours and 65°

C.

15. The brightness enhancing film of claim 9, wherein the UV absorber is a benzotriazole, benzatriazine, benzophenone, or a combination thereof.

19. A display device comprising:

a display panel;

a light source;

a reflective polarizer disposed between the display panel and the light source;

the brightness enhancing film of claim 9 disposed between the reflective polarizer and the light source, the first polymeric layer opposite the reflective polarizer; and

wherein the light source illuminates the display panel through the brightness enhancing film and the reflective polarizer.

20. The display device of claim 19, wherein the display panel is a liquid crystal display panel.

21. The display device of claim 19, wherein the display device is a television.