# US 11,442,211 B2 · Viewer for determination of authenticity

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- Number: US 11,442,211 B2
- Document ID: US11442211B2
- Status: Granted
- Kind: B2
- Application number: 16/646,567
- Filed: 2018-09-12
- Published: 2020-08-20
- Granted: 2022-09-13
- Earliest claimed: 2017-09-22
- Assignees: Zeon Corporation
- Applicants: Zeon Corporation
- Inventors: Koya Kawabata
- Web page: https://patentgrep.com/patent/US11442211B2

## CPC

- G02B 5/3041: {comprising multiple thin layers, e.g. multilayer stacks}
- 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)}
- B42D 25/22: for use in combination with accessories specially adapted for information-bearing cards
- B42D 25/364: Liquid crystals
- G02B 5/3025: {Polarisers, i.e. arrangements capable of producing a definite output polarisation state from an unpolarised input state (G02B5/3008, G02B5/3016 take precedence)}
- B42D 25/391: absorbing or reflecting polarised light
- G02B: OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- B42D: BOOKS; BOOK COVERS; LOOSE LEAVES; PRINTED MATTER CHARACTERISED BY IDENTIFICATION OR SECURITY FEATURES; PRINTED MATTER OF SPECIAL FORMAT OR STYLE NOT OTHERWISE PROVIDED FOR; DEVICES FOR USE THEREWITH AND NOT OTHERWISE PROVIDED FOR; MOVABLE-STRIP WRITING OR READING APPARATUS

## Abstract

An authenticity determination viewer including a first phase difference film, a linear polarizer, and a second phase difference film in this order, wherein a polarized light transmission axis of the linear polarizer and a slow axis of the first phase difference film are non-parallel to each other, and the polarized light transmission axis of the linear polarizer and a slow axis of the second phase difference film are non-parallel to each other.

## Claims

### Claim 1

An authenticity determination viewer comprising a first phase difference film, a linear polarizer, and a second phase difference film in this order, and further comprising a frame supporting the first phase difference film, the linear polarizer, and the second phase difference film, wherein
a polarized light transmission axis of the linear polarizer and a slow axis of the first phase difference film are non-parallel to each other,
the polarized light transmission axis of the linear polarizer and a slow axis of the second phase difference film are non-parallel to each other,
a first description is shown in a portion of the frame that comes into the sight of a user when a front-rear direction of the authenticity determination viewer is adjusted so that a reflected light from a marking containing a cholesteric resin passes through the authenticity determination viewer,
the first description indicates that the reflected light from the marking can pass through the authenticity determination viewer,
a second description is shown in a portion of the frame that comes into the sight of a user when the front-rear direction of the authenticity determination viewer is adjusted so that the reflected light from the marking is blocked by the authenticity determination viewer, and
the second description indicates that the reflected light from the marking can be blocked by the authenticity determination viewer.

### Claim 2 (depends on 1)

The authenticity determination viewer according to claim 1, wherein an angle formed between the slow axis of the first phase difference film and the slow axis of the second phase difference film is 0°±2°.

### Claim 3 (depends on 1)

The authenticity determination viewer according to claim 1, wherein
an angle formed between the polarized light transmission axis of the linear polarizer and the slow axis of the first phase difference film is 45°±2°, and
an angle formed between the polarized light transmission axis of the linear polarizer and the slow axis of the second phase difference film is 45°±2°.

### Claim 4 (depends on 1)

The authenticity determination viewer according to claim 1, wherein
an in-plane retardation of the first phase difference film at a measurement wavelength of 550 nm is 90 nm or more and 150 nm or less, and
an in-plane retardation of the second phase difference film at a measurement wavelength of 550 nm is 90 nm or more and 150 nm or less.

### Claim 5 (depends on 1)

The authenticity determination viewer according to claim 1, wherein the first phase difference film and the second phase difference film have reverse wavelength dispersion.

### Claim 6 (depends on 1)

The authenticity determination viewer according to claim 1, comprising the first phase difference film, a third phase difference film, the linear polarizer, a fourth phase difference film, and the second phase difference film in this order.

### Claim 7 (depends on 6)

The authenticity determination viewer according to claim 6, wherein
the first phase difference film and the second phase difference film are capable of functioning as a ¼ wave plate, and
the third phase difference film and the fourth phase difference film are capable of functioning as a ½ wave plate.

### Claim 8 (depends on 6)

The authenticity determination viewer according to claim 6, wherein
an in-plane retardation of the third phase difference film at a measurement wavelength of 550 nm is 240 nm or more and 300 nm or less, and
an in-plane retardation of the fourth phase difference film at a measurement wavelength of 550 nm is 240 nm or more and 300 nm or less.