Optical film composite for brightness enhancement including a birefringent polymer layer

• US 8,547,637 B2
• Filed: 12/28/2006
• Issued: 10/01/2013
• Est. Priority Date: 12/30/2005
• Status: Expired due to Fees

• Current Assignee: 3M Innovative Properties Company (3M Company)
• Original Assignee: 3M Innovative Properties Company (3M Company)
• Inventors: Kang, Myeong-Kyun, Kim, Yeon-Shin, Kim, Chi-Deuk, Seo, Kang-Il, Lee, Seo-Hern, Choi, Jong-Bok, Kim, Byoung-Kyu, Lee, Jong-Seo, Chae, Dong-Won
• Primary Examiner(s): FONT, FRANK G
• Application Number:
  US12/159,263
• Publication Number:
  US 20090303589A1
• Time in Patent Office: 2,469 Days
• Field of Search: 359/485.03, 359/489.01
• US Class Current: 359/485.03
• CPC Class Codes: B32B 2250/24 All layers being polymeric
• CPC Class Codes: B32B 2255/10 on synthetic resin layer or on natural or synthetic rubber layer
• CPC Class Codes: B32B 2255/26 Polymeric coating
• CPC Class Codes: B32B 2264/0214 Particles made of materials belonging to B32B27/00
• CPC Class Codes: B32B 2264/101 Glass
• CPC Class Codes: B32B 2307/42 Polarizing, birefringent, filtering
• CPC Class Codes: B32B 2307/518 bi-axially
• CPC Class Codes: B32B 2307/734 Dimensional stability
• CPC Class Codes: B32B 2457/202 LCD, i.e. liquid crystal displays
• CPC Class Codes: B32B 27/08 of synthetic resin
• CPC Class Codes: B32B 27/36 comprising polyesters
• CPC Class Codes: B32B 7/00 Layered products characterised by the relation between layers; Layered products characterised by the relative orientation of features between layers, or by the relative values of a measurable parameter between layers, i.e. products comprising layers having different physical, chemical or physicochemical properties; Layered products characterised by the interconnection of layers
• CPC Class Codes: B32B 7/023 Optical properties
• CPC Class Codes: B32B 7/03 with respect to the orientation of features direction of fibres or filaments B32B5/12
• CPC Class Codes: B32B 7/12 using interposed adhesives or interposed materials with bonding properties
• CPC Class Codes: G02B 5/3033 in the form of a thin sheet or foil, e.g. Polaroid
• CPC Class Codes: G02B 5/3083 Birefringent or phase retarding elements G02B5/3008, G02B5/3016 take precedence; systems for polarisation control G02B27/286; manufacturing phase modulating patterns by lithographic processes G03F7/001

Abstract

The present invention provides an optical film composite that includes a linear, reflective polarizing film; a first polymeric substrate layer having birefringence, which is placed on the reflective polarizing film; and a second polymeric substrate layer placed beneath the reflective polarizing film, wherein the optical axis of the first polymeric substrate layer is oriented with respect to the transmission axis of the reflective polarizing film to have of 0° to 25° of an angular difference between the axes. The optical film composite can be employed in LCD devices to improve optical performance.

Claims

1. An optical film composite comprising:

a linear, reflective polarizing film;

a first birefringent polymeric substrate layer having birefringence, which is placed on the reflective polarizing film, wherein the first birefringent polymeric substrate layer comprises an optical axis that corresponds to the axis having the highest index of refraction in the polymeric substrate layer; and

a second polymeric substrate layer placed beneath the reflective polarizing film, wherein the optical axis of the first polymeric substrate layer is oriented with respect to a transmission axis of the reflective polarizing film to have 0°

to 25°

of an angular difference between the axes.

2. The optical film composite of claim 1, wherein the reflective polarizing film is a multilayer polarizing film.

3. The optical film composite of claim 1, wherein the first polymeric substrate layer is a polyester based polymer layer.

4. The optical film composite of claim 1, wherein the second polymeric substrate layer is a polyester based polymer layer.

5. The optical film composite of claim 1, wherein the first polymeric substrate layer is treated to have a light diffusing function.

6. The optical film composite of claim 1, wherein the second polymeric substrate layer is treated to have a light diffusing function.

7. The optical film composite of claim 3, wherein the polyester based polymer is polyethylene terephthalate (PET).

8. The optical film composite of claim 4, wherein the polyester based polymer is polyethylene terephthalate (PET).

9. The optical film composite of claim 1, wherein the first polymeric substrate layer has a haze level of at least 20%.

10. The optical film composite of claim 1, wherein the second polymeric substrate layer has a haze level of at least 20%.

11. The optical film composite of claim 5, wherein the light diffusing function is imparted by a matte treatment.

12. The optical film composite of claim 5, wherein the light diffusing function is imparted by incorporating beads.

13. The optical film composite of claim 1, wherein the optical axis of the first polymeric substrate layer is oriented with respect to the transmission axis of the reflective polarizing film to have 0°

to 15°

of an angular difference of between the axes.

14. The optical film composite of claim 1, wherein the optical axis of the first polymeric substrate layer is oriented with respect to the transmission axis of the reflective polarizing film to have 0°

to 5°

of an angular difference of between the axes.

15. The optical film composite of claim 1, wherein the first polymeric substrate layer and the reflective polarizing film, or the second polymeric substrate layer and the reflective polarizing film are laminated by an optical adhesive.

16. The optical film composite of claim 15, wherein the optical adhesive is an acrylate based adhesive.

17. The optical film composite of claim 15, wherein the optical adhesive contains beads.

18. A liquid crystalline display device comprising the optical film composite according to claim 1.

19. A process for manufacturing an optical film composite, comprising the steps of:

providing a linear, reflective polarizing film;

placing a first polymeric substrate layer having birefringence on a side of the reflective polarizing film so that an angular difference between an optical axis of the first polymeric substrate layer and a transmission axis of the reflective polarizing film is 0°

to 25°

; and

placing a second polymeric substrate layer on the other side of the reflective polarizing film.

20. The process of claim 19, wherein the first polymeric substrate layer having birefringence is manufactured by a biaxial stretching method.