# US 10,372,966 B2 · Fingerprint sensing system and method

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- Number: US 10,372,966 B2
- Document ID: US10372966B2
- Status: Granted
- Kind: B2
- Application number: 15/457,954
- Filed: 2017-03-13
- Published: 2017-09-14
- Granted: 2019-08-06
- Earliest claimed: 2016-03-11
- Assignees: NXP B.V.
- Applicants: NXP B.V.
- Inventors: Thomas Suwald; Arne Burghardt
- Web page: https://patentgrep.com/patent/US10372966B2

## CPC

- G06V 40/1394: {using acquisition arrangements}
- G06V 40/1306: {non-optical, e.g. ultrasonic or capacitive sensing}
- G06V 40/1365: {Matching; Classification}
- G06V 40/14: Vascular patterns
- G06V: IMAGE OR VIDEO RECOGNITION OR UNDERSTANDING

## Abstract

According to a first aspect of the present disclosure, a fingerprint sensing system is provided, comprising: at least one sensing element configured and arranged to generate a sensing characteristic; a detection unit configured and arranged to detect changes of said sensing characteristic over time; a processing unit configured and arranged to determine if the changes of said sensing characteristic substantially conform to a predefined liveness function. According to a second aspect of the present disclosure, a corresponding fingerprint sensing method is conceived. According to a third aspect of the present disclosure, a corresponding computer program product is provided.

## Claims

### Claim 1

A fingerprint sensing system, comprising:
an array of capacitive sensors configured and arranged to measure capacitances caused by a portion of a finger located relative to the array of capacitive sensors, the capacitances comprising a first capacitance measured by at least one capacitive sensor in the array of capacitive sensors and a second capacitance measured by the at least one capacitive sensor, the first capacitance indicating a valley depth of a fingerprint of the finger at a first time and the second capacitance indicating the valley depth of the fingerprint at a second time;
a detection unit configured and arranged to detect changes of said capacitances over time based, in part, on the first capacitance and the second capacitance, wherein said capacitances change over time in response to changes in the valley depth of the fingerprint due to pulsating blood in the finger; and
a processing unit configured and arranged to determine if the changes of said capacitances substantially conform to a predefined liveness function, and to identify for each capacitance change, a relative position of a capacitive sensor in the array of capacitive sensors that is sensing the capacitance change.

### Claim 2 (depends on 1)

The system of claim 1, wherein the liveness function is a reference function stored in a storage unit of the fingerprint sensing system.

### Claim 3 (depends on 1)

The system of claim 1, wherein the processing unit is further configured and arranged to verify if the relative position is present in a predefined map of relative positions.

### Claim 4 (depends on 1)

The system of claim 1, wherein the processing unit is further configured and arranged to provide the relative position to a secure element.

### Claim 5 (depends on 3)

The system of claim 3, wherein the predefined map of relative positions represents a blood vessel pattern.

### Claim 6 (depends on 1)

The system of claim 1, wherein the array of capacitive sensors has the form of a matrix.

### Claim 7 (depends on 1)

The system of claim 1, wherein each of the array of capacitive sensors includes a sensing plate.

### Claim 8 (depends on 1)

A smart card comprising the fingerprint sensing system of claim 1.

### Claim 9

A method comprising:
measuring capacitances, using a plurality of capacitive sensors, the capacitances being caused by a portion of a finger positioned relative to the plurality of capacitive sensors, the capacitances comprising a first capacitance measured by at least one of the plurality of capacitive sensors and a second capacitance measured by the at least one of the plurality of capacitive sensors, the first capacitance indicating a valley depth of a fingerprint of the finger at a first time and the second capacitance indicating the valley depth of the fingerprint at a second time;
detecting changes of the capacitances over time based, in part, on the first capacitance and the second capacitance, wherein said capacitances change over time in response to changes in the valley depth of the fingerprint due to pulsating blood in the finger; and
determining if the changes of the capacitances substantially conform to a predefined liveness function, and to identify for each capacitance change, a relative position of a capacitive sensor in the plurality of capacitive sensors that is sensing the capacitance change.

### Claim 10 (depends on 9)

A computer program product stored on a non-transitory computer-readable medium, the computer program product comprising instructions which, when executed, carry out or control the method of claim 9.

### Claim 11 (depends on 9)

The method of claim 9, wherein the liveness function is a reference function stored in a storage unit of the fingerprint sensing method.

### Claim 12 (depends on 9)

The method of claim 9, further comprising verifying if the relative position is present in a predefined map of relative positions.