Laminated optical film, and liquid crystal panel and liquid crystal display apparatus using the laminated optical film

• US 8,154,694 B2
• Filed: 10/29/2007
• Issued: 04/10/2012
• Est. Priority Date: 12/07/2006
• Status: Active Grant

• Current Assignee: Nitto Denko Corporation
• Original Assignee: Nitto Denko Corporation
• Inventors: Shutou, Shunsuke, Kozonoi, Nobuyuki, Kawamoto, Ikuo, Motomura, Hironori, Bitou, Masato, Sabae, Misaki
• Primary Examiner(s): PEACE, RHONDA S
• Application Number:
  US12/516,043
• Publication Number:
  US 20100053510A1
• Time in Patent Office: 1,625 Days
• Field of Search: 349/98, 349117-119, 349/121
• US Class Current: 349/118
• CPC Class Codes: B32B 2250/24 All layers being polymeric
• CPC Class Codes: B32B 2270/00 Resin or rubber layer containing a blend of at least two different polymers
• CPC Class Codes: B32B 23/04 comprising such cellulosic plastic substance as the main or only constituent of a layer, which is next to another layer of the same or of a different material next to a glass layer B32B17/08
• CPC Class Codes: B32B 23/08 of synthetic resin
• CPC Class Codes: B32B 2307/306 Resistant to heat
• CPC Class Codes: B32B 2307/40 having particular optical properties
• CPC Class Codes: B32B 2307/4026 within the layer by addition of a colorant, e.g. pigments, dyes
• CPC Class Codes: B32B 2307/412 Transparent
• CPC Class Codes: B32B 2307/418 Refractive
• CPC Class Codes: B32B 2307/514 Oriented
• CPC Class Codes: B32B 2307/714 Inert, i.e. inert to chemical degradation, corrosion
• 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 27/281 comprising polyimides
• CPC Class Codes: B32B 27/283 comprising polysiloxanes
• CPC Class Codes: B32B 27/285 comprising polyethers
• CPC Class Codes: B32B 27/286 comprising polysulphones; polysulfides
• CPC Class Codes: B32B 27/302 comprising aromatic vinyl (co)polymers, e.g. styrenic (co)polymers
• CPC Class Codes: B32B 27/304 comprising vinyl halide (co)polymers, e.g. PVC, PVDC, PVF, PVDF
• CPC Class Codes: B32B 27/306 comprising vinyl acetate or vinyl alcohol (co)polymers
• CPC Class Codes: B32B 27/308 : comprising acrylic (co)polymers
• CPC Class Codes: B32B 27/32 : comprising polyolefins comprising vinyl (co)polymers or acrylic (co)polymers B32B27/30
• CPC Class Codes: B32B 27/322 : comprising halogenated polyolefins, e.g. PTFE
• CPC Class Codes: B32B 27/325 : comprising polycycloolefins
• CPC Class Codes: B32B 27/34 : comprising polyamides
• CPC Class Codes: B32B 27/36 : comprising polyesters
• CPC Class Codes: B32B 27/365 : comprising polycarbonates
• CPC Class Codes: B32B 27/38 : comprising epoxy resins
• CPC Class Codes: B32B 27/40 : comprising polyurethanes
• 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 5/3016 : involving passive liquid crystal elements optical properties of liquid crystals G02F1/0063; polarising elements associated with active liquid crystal devices G02F1/133528
• 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
• CPC Class Codes: G02F 1/133528 : Polarisers
• CPC Class Codes: G02F 1/133541 : Circular polarisers
• CPC Class Codes: G02F 1/133634 : the refractive index Nz perpendicular to the element surface being different from in-plane refractive indices Nx and Ny, e.g. biaxial or with normal optical axis
• CPC Class Codes: G02F 2203/09 : transflective

Abstract

Provided are a laminated optical film capable of enhancing a contrast ratio in an oblique direction remarkably while enhancing viewing angle characteristics when being used in a liquid crystal display apparatus or the like, and a liquid crystal panel and a liquid crystal display apparatus using the laminated optical film. The laminated optical film of the present invention includes a polarizer, a first optical compensation layer, and a second optical compensation layer in the stated order, in which the first optical compensation layer has a refractive index profile of nx>nz>ny and is placed so that a slow axis direction thereof is substantially parallel to or substantially perpendicular to an absorption axis direction of the polarizer, and the second optical compensation layer converts linearly polarized light into circularly polarized light or circularly polarized light into linearly polarized light in a visible light region.

Claims

1. A laminated optical film, comprising a polarizer, a first optical compensation layer, and a second optical compensation layer, in the stated order, wherein:

the first optical compensation layer has a refractive index profile of nx>

nz>

ny and is placed so that a slow axis direction thereof is substantially parallel to or substantially perpendicular to an absorption axis direction of the polarizer,

the second optical compensation layer converts linearly polarized light into circularly polarized light or circularly polarized light into linearly polarized light in a visible light region, and

the second optical compensation layer is placed so that the slow axis direction is not substantially parallel to or not substantially perpendicular to the absorption axis direction of the polarizer.

2. A laminated optical film according to claim 1, wherein the first optical compensation layer has an Nz coefficient of 0.1 to 0.6.

3. A laminated optical film according to claim 1, wherein the first optical compensation layer is formed of one retardation film (A).

4. A laminated optical film according to claim 3, wherein the retardation film (A) contains at least one kind of thermoplastic resin selected from a norbornene-based resin, a cellulose-based resin, a carbonate-based resin, and an ester-based resin.

5. A laminated optical film according to claim 1, wherein the second optical compensation layer is formed of one retardation film (B), and is placed so that a slow axis direction of the retardation film (B) is placed substantially at an angle of 45°

with respect to the absorption axis direction of the polarizer.

6. A laminated optical film according to claim 5, wherein the retardation film (B) has an in-plane retardation Re[590] at a wavelength of 590 nm larger than an in-plane retardation Re[480] at a wavelength of 480 nm.

7. A laminated optical film according to claim 5, wherein the retardation film (B) includes at least one kind of thermoplastic resin selected from a cellulose-based resin, a carbonate-based resin, a vinyl acetal-based resin, and a norbornene-based resin.

8. A laminated optical film according to claim 1, wherein the second optical compensation layer is formed of two retardation films (C) and (D), the retardation film (C) is placed between the polarizer and the retardation film (D), and an angle α

°

formed by a slow axis direction of the retardation film (C) and an absorption axis direction of the polarizer and an angle β

°

formed by a slow axis direction of the retardation film (D) and an absorption axis direction of the polarizer have a relationship of (2α

+30)<

β

<

(2α

+60).

9. A laminated optical film according to claim 8, wherein the retardation film (C) has an in-plane retardation Re[590] at a wavelength of 590 nm equal to or less than an in-plane retardation Re[480] at a wavelength of 480 nm.

10. A laminated optical film according to claim 8, wherein the retardation film (D) has an in-plane retardation Re[590] at a wavelength of 590 nm equal to or less than an in-plane retardation Re[480] at a wavelength of 480 nm.

11. A laminated optical film according to claim 8, wherein the retardation film (C) and/or the retardation film (D) includes at least one kind of thermoplastic resin chosen from a norbornene-based resin and a carbonate-based resin.

12. A laminated optical film according to claim 1, comprising a third optical compensation layer on a side of the second optical compensation layer opposite to the first optical compensation layer, wherein the third optical compensation layer has a refractive index profile of nx=ny>

nz.

13. A laminated optical film according to claim 12, wherein the third optical compensation layer includes a retardation film formed of a cholesteric alignment fixed layer.

14. A laminated optical film according to claim 12, wherein the third optical compensation layer includes a retardation film containing an imide-based resin.

15. A liquid crystal panel, comprising the laminated optical film according to claim 1.

16. A liquid crystal display apparatus, comprising the liquid crystal panel according to claim 15.