# US 12,118,819 B2 · Fingerprint recognition sensor and optical element

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- Number: US 12,118,819 B2
- Document ID: US12118819B2
- Status: Granted
- Kind: B2
- Application number: 18/474,861
- Filed: 2023-09-26
- Published: 2024-01-18
- Granted: 2024-10-15
- Earliest claimed: 2021-03-30
- Assignees: FUJIFILM Corporation
- Applicants: FUJIFILM Corporation
- Inventors: Ryoji Himeno; Shinichi Morishima; Yuki Hirai; Makoto Kamo; Megumi Sekiguchi
- Web page: https://patentgrep.com/patent/US12118819B2

## CPC

- G06V 40/1318: {using electro-optical elements or layers, e.g. electroluminescent sensing}
- A61B 5/1172: using fingerprinting
- G01N 21/21: Polarisation-affecting properties (G01N21/19 takes precedence)
- G01N 21/359: using near infrared light
- G02B 5/208: {for use with infrared or ultraviolet radiation, e.g. for separating visible light from infrared and/or ultraviolet radiation}
- G02B 5/22: Absorbing filters {(G02B5/201 - G02B5/208 take precedence)}
- G02B 5/30: Polarising elements (light-modulating devices with active elements G02F1/00)
- G06V: IMAGE OR VIDEO RECOGNITION OR UNDERSTANDING
- A61B: DIAGNOSIS; SURGERY; IDENTIFICATION (usefulness limited to only animals A61D)
- G01N: INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES (measuring or testing apparatus or processes other than immunoassay, involving enzymes or microorganisms C12M, C12Q)
- G02B: OPTICAL ELEMENTS, SYSTEMS OR APPARATUS

## Abstract

A fingerprint recognition sensor having an excellent S/N ratio and capable of realizing thinning and an optical element including the fingerprint recognition sensor. The fingerprint recognition sensor includes a light-receiving element; and an optical element including a near infrared absorbing dichroic substance, in which a fingerprint reading surface is positioned on a side of the optical element opposite to the light-receiving element side. The optical element has an absorption axis with respect to near infrared light in an in-plane direction. When linearly polarized light of near infrared light orthogonal to the absorption axis is radiated from a normal direction of the optical element and from a direction inclined by 45° from the normal direction at an azimuthal angle orthogonal to the absorption axis, an absorbance during the radiation from the direction inclined by 45° from the normal direction is more than an absorbance during the radiation from the normal direction.

## Claims

### Claim 1

A fingerprint recognition sensor comprising:
a light-receiving element; and
an optical element that includes a near infrared absorbing dichroic substance,
wherein a fingerprint reading surface is positioned on a side of the optical element opposite to the light-receiving element side,
the optical element has an absorption axis with respect to near infrared light in an in-plane direction, and
in a case where linearly polarized light of near infrared light orthogonal to the absorption axis is radiated from a normal direction of the optical element and from a direction inclined by 45° from the normal direction at an azimuthal angle orthogonal to the absorption axis, an absorbance during the radiation from the direction inclined by 45° from the normal direction is more than an absorbance during the radiation from the normal direction.

### Claim 2 (depends on 1)

The fingerprint recognition sensor according to claim 1,
wherein the optical element includes a first layer that includes a near infrared absorbing dichroic substance and has an absorption axis with respect to near infrared light in an in-plane direction and a second layer that includes a near infrared absorbing dichroic substance and has an absorption axis with respect to near infrared light in a thickness direction.

### Claim 3 (depends on 2)

The fingerprint recognition sensor according to claim 2,
wherein the first layer and the second layer are layers that do not substantially absorb visible light.

### Claim 4 (depends on 1)

The fingerprint recognition sensor according to claim 1,
wherein the optical element consists of a single layer that includes a near infrared absorbing dichroic substance and has an absorption axis with respect to near infrared light in an in-plane direction, and
in a cross-section taken along the absorption axis, the optical element does not have absorption anisotropy with respect to near infrared light.

### Claim 5 (depends on 4)

The fingerprint recognition sensor according to claim 4,
wherein the near infrared absorbing dichroic substance is a substance that does not substantially absorb visible light.

### Claim 6 (depends on 4)

The fingerprint recognition sensor according to claim 4,
wherein the near infrared absorbing dichroic substance is a disk-like colorant.

### Claim 7 (depends on 5)

The fingerprint recognition sensor according to claim 5,
wherein the near infrared absorbing dichroic substance is a disk-like colorant.