Reflective Polarizer and Display Device Having the Same

• US 20070014009A1
• Filed: 05/16/2006
• Published: 01/18/2007
• 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: Zhang, Wei, Nelson, Eric, Cross, Elisa, Invie, Judith
• Granted Patent: US 7,557,989 B2
• Time in Patent Office: Days
• US Class Current: 359/498
• CPC Class Codes: G02B 5/305 including organic materials, e.g. polymeric layers
• CPC Class Codes: G02F 1/133536 Reflective polarizers G02F1/13362 takes precedence
• CPC Class Codes: G02F 1/133545 Dielectric stack polarisers

Abstract

A reflective polarizer suitable for use in a display device is disclosed herein. The reflective polarizer comprises: a multilayer optical film comprising alternating layers of first and second polymeric layers that reflects light of a first polarization state and transmits light of a second polarization state, wherein for normally incident light of the second polarization state, the reflective polarizer has an internal percent transmission of at least 95% at 410 nm, and at most 25% at 380 nm. Also disclosed herein is a display device comprising the reflector polarizer.

Claims

1. A reflective polarizer suitable for use in a display device, the article comprising:

a multilayer optical film comprising alternating layers of first and second polymeric layers, the first and second polymeric layers having refractive indices along an in-plane x-axis that differ sufficiently to substantially reflect light of a first polarization state, the first and second polymeric layers having refractive indices along an in-plane y-axis that are matched sufficiently to substantially transmit light of a second polarization state, wherein the x- and y-axes are orthogonal, wherein at least one of the first and second polymeric layers comprises naphthalate functionality;

first and second support layers disposed on opposite sides of the multilayer optical film and adhered thereto by first and second adhesive layers, respectively, the first and second support layers being light transmissive;

wherein at least one of the first and second polymeric layers, the first and second support layer, and the first and second adhesive layers comprises a UV absorber that absorbs UV light and transmits visible light, such that for normally incident light of the second polarization state, the reflective polarizer has an internal percent transmission of at least 95% at 410 nm, and at most 25% at 380 nm.

2. The reflective polarizer of claim 1, wherein at least one of the first and second polymeric layers comprises the UV absorber, and the UV absorber is not present in the first and second support layers or the first and second adhesive layers.

3. The reflective polarizer of claim 1, wherein at least one of the first and second support layers comprises the UV absorber, and the UV absorber is not present in the first and second polymeric layers or the first and second adhesive layers.

4. The reflective polarizer of claim 1, wherein at least one of the first and second adhesive layers comprises the UV absorber, and the UV absorber is not present in the first and second polymeric layers or the first and second support layers.

5. The reflective polarizer of claim 1, wherein at least one of the first support layer and the first adhesive layer comprises the UV absorber, and the UV absorber is not present in the first and second polymeric layers, the second support layer, or the second adhesive layer.

6. The reflective polarizer of claim 1, wherein b* is about 2.5 or less.

7. The reflective polarizer of claim 1, such that for normally incident light of the second polarization state, the internal percent transmission at 380 nm is at most 15%.

8. The reflective polarizer of claim 1, wherein the reflective polarizer 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.

9. The reflective polarizer of claim 1, wherein at least one of the first and second polymeric layers comprises naphthalate functionality.

10. The reflective polarizer of claim 1, wherein the first and second adhesive layers are curable using UV or visible radiation.

11. The reflective polarizer of claim 1, wherein the UV absorber is a benzotriazole, a benzatriazine, a benzophenone, or a combination thereof.

12. A reflective polarizer suitable for use in a display device, the reflective polarizer comprising:

a multilayer optical film comprising alternating layers of first and second polymeric layers, the first and second polymeric layers having refractive indices along an in-plane x-axis that differ sufficiently to substantially reflect light of a first polarization state, the first and second polymeric layers having refractive indices along an in-plane y-axis that are matched sufficiently to substantially transmit light of a second polarization state, wherein the x- and y-axes are orthogonal, wherein at least one of the first and second polymeric layers comprises naphthalate functionality; and

first and second skin layers disposed on opposite sides of the multilayer optical film;

wherein at least one of the first and second polymeric layers and the first and second skin layers comprises a UV absorber that absorbs UV light and transmits visible light, such that for normally incident light of the second polarization state, the reflective polarizer has an internal percent transmission of at least 95% at 410 nm, and at most 25% at 380 nm.

13. The reflective polarizer of claim 12, wherein at least one of the first and second skin layers comprises the UV absorber.

14. A reflective polarizer suitable for use in a display device, the reflective polarizer comprising:

a multilayer optical film comprising alternating layers of first and second polymeric layers, the first and second polymeric layers having refractive indices along an in-plane x-axis that differ sufficiently to substantially reflect light of a first polarization state, the first and second polymeric layers having refractive indices along an in-plane y-axis that are matched sufficiently to substantially transmit light of a second polarization state, wherein the x- and y-axes are orthogonal, wherein at least one of the first and second polymeric layers comprises naphthalate functionality;

first and second outer layers disposed on opposite sides of the multilayer optical film;

a first support layer disposed between the multilayer optical film and the first outer layer; and

a second support layer disposed between the multilayer optical film and the second outer layer;

wherein the first and second support layers are light transmissive, and

wherein at least one of the first and second polymeric layers, the first and second outer layers, and the first and second support layers comprises a UV absorber that absorbs UV light and transmits visible light, such that for normally incident light of the second polarization state, the reflective polarizer has an internal percent transmission of at least 95% at 410 nm, and at most 25% at 380 nm.

15. The reflective polarizer of claim 14, wherein at least one of the first and second outer layers comprises the UV absorber.

16. A reflective polarizer suitable for use in a display device, the article comprising:

a multilayer optical film comprising alternating layers of first and second polymeric layers, the first and second polymeric layers having refractive indices along an in-plane x-axis that differ sufficiently to substantially reflect light of a first polarization state, the first and second polymeric layers having refractive indices along an in-plane y-axis that are matched sufficiently to substantially transmit light of a second polarization state, wherein the x- and y-axes are orthogonal, wherein at least one of the first and second polymeric layers comprises naphthalate functionality;

a support layer disposed on a first side of a multilayer optical film and adhered thereto by an adhesive layer, the support layer being light transmissive;

wherein at least one of the first and second polymeric layers, the support layer, and the adhesive layer comprises a UV absorber that absorbs UV light and transmits visible light, such that for normally incident light of the second polarization state, the reflective has an internal percent transmission of at least 95% at 410 nm, and at most 25% at 380 nm.

17. A reflective polarizer suitable for use in a display device, the article comprising:

a multilayer optical film comprising alternating layers of first and second polymeric layers, the first and second polymeric layers having refractive indices along an in-plane x-axis that differ sufficiently to substantially reflect light of a first polarization state, the first and second polymeric layers having refractive indices along an in-plane y-axis that are matched sufficiently to substantially transmit light of a second polarization state, wherein the x- and y-axes are orthogonal, wherein at least one of the first and second polymeric layers comprises naphthalate functionality;

an outer layer disposed on one side of the multilayer optical film; and

a support layer disposed between the multilayer optical film and the outer layer, the support layer being light transmissive;

wherein at least one of the first and second polymeric layers, the outer layer, and the support layer comprises a UV absorber that absorbs UV light and transmits visible light, such that for normally incident light of the second polarization state, the reflective polarizer has an internal percent transmission of at least 95% at 410 nm, and at most 25% at 380 nm.

18. A display device comprising:

a display panel,

a light source, and

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

a multilayer optical film comprising alternating layers of first and second polymeric layers, the first and second polymeric layers having refractive indices along an in-plane x-axis that differ sufficiently to substantially reflect light of a first polarization state, the first and second polymeric layers having refractive indices along an in-plane y-axis that are matched sufficiently to substantially transmit light of a second polarization state, wherein the x- and y-axes are orthogonal, wherein at least one of the first and second polymeric layers comprises naphthalate functionality;

wherein for normally incident light of the second polarization state, the reflective polarizer has an internal percent transmission of at least 95% at 410 nm, and at most 25% at 380 nm.

19. The display device of claim 18, wherein the display panel is a liquid crystal display panel.

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