# US 7,746,424 B2 · High luminance polarizing plate, and liquid crystal panel and image display using same

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- Number: US 7,746,424 B2
- Document ID: US7746424B2
- Status: Granted
- Kind: B2
- Application number: 10/548,085
- Filed: 2004-03-01
- Published: 2006-08-17
- Granted: 2010-06-29
- Earliest claimed: 2003-03-07
- Assignees: Nitto Denko Corporation
- Inventors: Tadayuki Kameyama; Naoki Takahashi
- Web page: https://patentgrep.com/patent/US7746424B2

## CPC

- G02F 1/133528: {Polarisers}
- G02F 1/133507: {Films for enhancing the luminance}
- 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}
- G02F 2202/28: Adhesive materials or arrangements
- H10K 59/8791: {Arrangements for improving contrast, e.g. preventing reflection of ambient light}
- G02F: OPTICAL DEVICES OR ARRANGEMENTS FOR THE CONTROL OF LIGHT BY MODIFICATION OF THE OPTICAL PROPERTIES OF THE MEDIA OF THE ELEMENTS INVOLVED THEREIN; NON-LINEAR OPTICS; FREQUENCY-CHANGING OF LIGHT; OPTICAL LOGIC ELEMENTS; OPTICAL ANALOGUE/DIGITAL CONVERTERS
- H10K: ORGANIC ELECTRIC SOLID-STATE DEVICES

## Abstract

A high-brightness polarizing plate of the present invention comprises a polarizing plate that comprises a polarizer and a protective film prepared on one or both sides of the polarizer, a brightness enhancement film and an adhesive layer through which the polarizing plate and the brightness enhancement film are laminated with the protective film interposed between them, wherein the protective film has an in-plane retardation Re of 0 to 10 nm and a thickness-direction retardation Rth of −30 to 10 nm, wherein Re=(nx−ny)d and Rth={(nx+ny)/(2−nz)}d. The high-brightness polarizing plate has a small color shift, and can be applied to various image displays such as liquid crystal displays.

## Claims

### Claim 1

A high-brightness polarizing plate, comprising: a polarizing plate;
wherein the polarizing plate comprises a polarizer and a protective film prepared on one or both sides of the polarizer, and the polarizer and the protective film are adhered with an adhesive;
a brightness enhancement film; and an adhesive layer through which the polarizing plate and the brightness enhancement film are laminated with the protective film interposed between them, wherein
the protective film has an in-plane retardation Re of 0 to 10 nm and a thickness-direction retardation Rth of −30 to 10 nm, wherein
Re=(nx−ny)d and Rth={(nx+ny)/(2−nz)} d, wherein
nx is a refractive index in an X-axis direction in which a maximum in-plane refractive index is obtained, ny is a refractive index in a Y-axis direction perpendicular to the X-axis, nz is a refractive index in a Z-axis direction which is the film thickness direction, and d is a thickness (nm) of the protective film.

### Claim 2 (depends on 1)

The high-brightness polarizing plate according to claim 1, wherein the protective film contains (A) a thermoplastic resin having a substituted and/or unsubstituted imide group in side chain and (B) a thermoplastic resin having a substituted and/or unsubstituted phenyl and nitrile groups in side chain.

### Claim 3 (depends on 1)

The high-brightness polarizing plate according to claim 1, wherein the protective film is a biaxially stretched film.

### Claim 4 (depends on 1)

The high-brightness polarizing plate according to claim 1, wherein the polarizer is an iodine-containing polyvinyl alcohol-based film.

### Claim 5 (depends on 1)

The high-brightness polarizing plate according to claim 1, wherein the brightness enhancement film is an anisotropic reflection polarizer.

### Claim 6 (depends on 5)

The high-brightness polarizing plate according to claim 5, wherein the anisotropic reflection polarizer is a composite of a cholesteric liquid crystal layer and a quarter wavelength plate.

### Claim 7 (depends on 5)

The high-brightness polarizing plate according to claim 5, wherein the anisotropic reflection polarizer is an anisotropic multilayered thin film capable of transmitting linearly polarized light in one direction of vibration and reflecting linearly polarized light that in another direction of vibration.

### Claim 8 (depends on 5)

The high-brightness polarizing plate according to claim 5, wherein the anisotropic reflection polarizer is a reflective grid polarizer.

### Claim 9 (depends on 1)

The high-brightness polarizing plate according to claim 1, wherein the brightness enhancement film is an anisotropic scattering polarizer.

### Claim 10 (depends on 1)

A high-brightness polarizing plate, comprising the high-brightness polarizing plate according to claim 1 and at least one optical film.

### Claim 11 (depends on 1)

A liquid crystal panel, comprising a liquid crystal cell and the high-brightness polarizing plate according to claim 1 attached to at least one side of the liquid crystal cell.

### Claim 12 (depends on 11)

A liquid crystal display, comprising the liquid crystal panel according to claim 11.

### Claim 13 (depends on 1)

An image viewing display, comprising the high-brightness polarizing plate according to claim 1.