# US 10,310,286 B2 · Circularly polarizing plate, method for producing same, broadband lambda/4 plate, organic electroluminescent display device, and liquid crystal display device

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- Number: US 10,310,286 B2
- Document ID: US10310286B2
- Status: Granted
- Kind: B2
- Application number: 15/512,192
- Filed: 2015-09-16
- Published: 2017-10-19
- Granted: 2019-06-04
- Earliest claimed: 2014-09-26
- Assignees: Zeon Corporation
- Applicants: Zeon Corporation
- Inventors: Kazuhiro Osato
- Web page: https://patentgrep.com/patent/US10310286B2

## CPC

- G02B 27/286: {for controlling or changing the state of polarisation, e.g. transforming one polarisation state into another (G02B5/3083 takes precedence; light guide coupling means utilising polarising elements G02B6/34)}
- 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)}
- G02F 1/133528: {Polarisers}
- G02F 1/13363: Birefringent elements, e.g. for optical compensation
- G09G 3/3208: organic, e.g. using organic light-emitting diodes [OLED]
- H05B 33/02: Details
- G02F 1/133541: {Circular polarisers}
- G02B: OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- 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
- G09G: ARRANGEMENTS OR CIRCUITS FOR CONTROL OF INDICATING DEVICES USING STATIC MEANS TO PRESENT VARIABLE INFORMATION (arrangements for transferring data between digital computers and displays G06F3/14; static indicating arrangements comprising an association of a number of separate sources or light control cells G09F9/00; static indicating arrangements comprising integral associations of a number of light sources H01J, H01K, H10H, H05B33/12; scanning, transmission or reproduction of documents or the like, e.g. facsimile transmission, details thereof H04N1/00)
- H05B: ELECTRIC HEATING; ELECTRIC LIGHT SOURCES NOT OTHERWISE PROVIDED FOR; CIRCUIT ARRANGEMENTS FOR ELECTRIC LIGHT SOURCES, IN GENERAL

## Abstract

A circularly polarizing plate including a polarizing film, a λ/2 plate having a slow axis in a direction forming an angle of 22.5°±10° relative to an absorption axis of the polarizing film, a λ/4 plate having a slow axis in a direction forming an angle of 90°±20° relative to the absorption axis of the polarizing film, in this order, wherein the λ/2 plate and the λ/4 plate have different wavelength dispersions, an NZ factor of the λ/2 plate is 1.00±0.05, and an NZ factor of the λ/4 plate is 0.00±0.05; a method for producing the same, and a method for using the same.

## Claims

### Claim 1

A circularly polarizing plate comprising:
a polarizing film;
a λ/2 plate having a slow axis in a direction forming an angle of 22.5°±10° relative to an absorption axis of the polarizing film; and
a λ/4 plate having a slow axis in a direction forming an angle of 90°±20° relative to the absorption axis of the polarizing film, in this order, wherein
the λ/2 plate and the λ/4 plate have different wavelength dispersions,
an NZ factor of the λ/2 plate is 1.00±0.05, and
an NZ factor of the λ/4 plate is 0.00±0.05, wherein
the NZ factor is a value represented by (nx−nz)/(nx−ny), where nx represents a refractive index in a direction in which the maximum refractive index is given among directions perpendicular to the thickness direction (in-plane directions), ny represents a refractive index in one of the in-plane directions that is orthogonal to the nx direction, and nz represents a refractive index in a thickness direction.

### Claim 2 (depends on 1)

The circularly polarizing plate according to claim 1, satisfying the following formula (A):
Reh(400)/Reh(550)<Req(400)/Req(550)
wherein Reh(400) is an in-plane phase difference of the λ/2 plate at a wavelength of 400 nm,
Reh(550) is an in-plane phase difference of the λ/2 plate at a wavelength of 550 nm,
Req(400) is an in-plane phase difference of the λ/4 plate at a wavelength of 400 nm, and
Req(550) is an in-plane phase difference of the λ/4 plate at a wavelength of 550 nm.

### Claim 3 (depends on 1)

The circularly polarizing plate according to claim 1, satisfying the following formula (B):
Req(400)/Req(550)−Reh(400)/Reh(550)=0.12±0.08
wherein Reh(400) is an in-plane phase difference of the λ/2 plate at a wavelength of 400 nm,
Reh(550) is an in-plane phase difference of the λ/2 plate at a wavelength of 550 nm,
Req(400) is an in-plane phase difference of the λ/4 plate at a wavelength of 400 nm, and
Req(550) is an in-plane phase difference of the λ/4 plate at a wavelength of 550 nm.

### Claim 4 (depends on 1)

The circularly polarizing plate according to claim 1, wherein the λ/4 plate includes a layer formed of a material having a negative intrinsic birefringence value.

### Claim 5 (depends on 1)

The circularly polarizing plate according to claim 1, wherein the λ/2 plate includes a layer formed of a material having a positive intrinsic birefringence value.

### Claim 6 (depends on 1)

An organic electroluminescent display device comprising the circularly polarizing plate according to claim 1.

### Claim 7 (depends on 1)

A liquid crystal display device comprising the circularly polarizing plate according to claim 1.

### Claim 8

A broadband λ/4 plate comprising:
a λ/2 plate having a slow axis in a direction forming an angle of 22.5°±10° relative to a reference direction; and
a λ/4 plate having a slow axis in a direction forming an angle of 90°±20° relative to the reference direction,
wherein the λ/2 plate and the λ/4 plate have different wavelength dispersions,
an NZ factor of the λ/2 plate is 1.00±0.05, and
an NZ factor of the λ/4 plate is 0.00±0.05, wherein
the NZ factor is a value represented by (nx−nz)/(nx−ny), where nx represents a refractive index in a direction in which the maximum refractive index is given among directions perpendicular to the thickness direction (in-plane directions), ny represents a refractive index in one of the in-plane directions that is orthogonal to the nx direction, and nz represents a refractive index in a thickness direction.

### Claim 9

A method for producing a circularly polarizing plate, comprising the steps of:
stretching a first pre-stretch film including a layer formed of a material having a positive intrinsic birefringence value in one direction to obtain a λ/2 plate having a slow axis in a stretching direction;
stretching a second pre-stretch film including a layer formed of a material having a negative intrinsic birefringence value in one direction to obtain a λ/4 plate having a slow axis in a direction perpendicular to a stretching direction;
bonding a polarizing film and the λ/2 plate together such that a slow axis of the λ/2 plate forms an angle of 22.5°±10° relative to an absorption axis of the polarizing film; and
bonding the λ/2 plate and the λ/4 plate together such that a slow axis of the λ/4 plate forms an angle of 90°±20° relative to the absorption axis of the polarizing film, wherein
the λ/2 plate and the λ/4 plate have different wavelength dispersions,
an NZ factor of the λ/2 plate is 1.00±0.05, and
an NZ factor of the λ/4 plate is 0.00±0.05, wherein
the NZ factor is a value represented by (nx−nz)/(nx−ny), where nx represents a refractive index in a direction in which the maximum refractive index is given among directions perpendicular to the thickness direction (in-plane directions), ny represents a refractive index in one of the in-plane directions that is orthogonal to the nx direction, and nz represents a refractive index in a thickness direction.

### Claim 10

A method for producing a circularly polarizing plate, comprising the steps of:
stretching a first pre-stretch film including a layer formed of a material having a positive intrinsic birefringence value in one direction to obtain a λ/2 plate having a slow axis in a stretching direction;
forming a layer containing a discotic liquid crystalline molecule on a supporting body, orienting the discotic liquid crystalline molecule, and fixing the discotic liquid crystalline molecule to obtain a λ/4 plate;
bonding a polarizing film and the λ/2 plate together such that a slow axis of the λ/2 plate forms an angle of 22.5°±10° relative to an absorption axis of the polarizing film; and
bonding the λ/2 plate and the λ/4 plate together such that a slow axis of the λ/4 plate forms an angle of 90°±20° relative to the absorption axis of the polarizing film, wherein
the λ/2 plate and the λ/4 plate have different wavelength dispersions,
an NZ factor of the λ/2 plate is 1.00±0.05, and
an NZ factor of the λ/4 plate is 0.00±0.05, wherein
the NZ factor is a value represented by (nx−nz)/(nx−ny), where nx represents a refractive index in a direction in which the maximum refractive index is given among directions perpendicular to the thickness direction (in-plane directions), ny represents a refractive index in one of the in-plane directions that is orthogonal to the nx direction, and nz represents a refractive index in a thickness direction.