FINGERPRINT SENSOR AND CORRECTION METHOD THEREOF

• US 20170185819A1
• Filed: 03/15/2017
• Published: 06/29/2017
• Est. Priority Date: 01/13/2015
• Status: Active Grant

• Current Assignee: Shenzhen Goodix Technology Co., Ltd.
• Original Assignee: Shenzhen Huiding Technology Co., Ltd. (Shenzhen Goodix Technology Co., Ltd.)
• Inventors: PANG, Shu, CAI, Xiaochun, HUANG, Hui
• Granted Patent: US 10,643,048 B2
• Time in Patent Office: Days
• CPC Class Codes: G06V 10/12 Details of acquisition arrangements; Constructional details thereof
• CPC Class Codes: G06V 10/993 Evaluation of the quality of the acquired pattern
• CPC Class Codes: G06V 40/1306 non-optical, e.g. ultrasonic or capacitive sensing
• CPC Class Codes: G06V 40/1365 Matching; Classification

Abstract

A fingerprint sensor and a correction method thereof are provided. The fingerprint sensor includes a sensing part to be touched by a finger, including sensing units, a processing unit, and a correction unit; the sensing unit is configured to sense, when correction starts, a fingerprint signal and output first data; the processing unit is configured to calculate, according to a mathematical model, a new correction coefficient of the corresponding sensing unit by the first data; and the correction unit is configured to correct, according to the new correction coefficient, second data output by the corresponding sensing unit. The fingerprint sensor can automatically modify a correction coefficient when a physical characteristic of the fingerprint sensor changes, thereby reducing the product return rate and prolonging the product service life, omitting a step of correction before delivery, and reducing the manufacturing difficulty and the manufacturing costs.

Claims

1. A fingerprint sensor, comprising a sensing part to be touched by a finger, the sensing part comprising a plurality of sensing units, wherein the fingerprint sensor further comprises a processing unit and a correction unit, wherein:

the sensing unit is configured to sense, when correction starts, a fingerprint signal and output first data;

the processing unit is configured to calculate, according to a mathematical model, a new correction coefficient of the corresponding sensing unit by using the first data; and

the correction unit is configured to correct, according to the new correction coefficient, second data output by the corresponding sensing unit.

2. The fingerprint sensor according to claim 1, further comprising a storage unit, configured to store a correction coefficient, wherein if an old correction coefficient is stored in the fingerprint sensor, the old correction coefficient is replaced with the new correction coefficient, or the old correction coefficient is replaced with a weighted sum of the new correction coefficient and the old correction coefficient.

3. The fingerprint sensor according to claim 2, further comprising a determining unit, configured to determine whether a correction condition is satisfied, wherein the correction condition comprises one or more of the following:

the fingerprint sensor is enabled for the first time, a preset correction time is reached, a correction instruction is received, or an effect of correction by means of the old correction coefficient does not reach a designated requirement.

4. The fingerprint sensor according to claim 3, wherein the effect of correction by means of the old correction coefficient is evaluated by using an image smoothness or a root-mean-square error of data that is output by all the sensing units and corrected by means of the old correction coefficient, and if the an image smoothness or the root-mean-square error is greater than a preset threshold, the designated requirement is not reached.

5. The fingerprint sensor according to claim 1, wherein the processing unit comprises a first calculation subunit, configured to calculate, according to the mathematical model, a new correction coefficient of the corresponding sensing unit by using the first data and the old correction coefficient of the corresponding sensing unit,

6. The fingerprint sensor according to claim 1, wherein

the sensing unit is further configured to:

obtain a frame of data output by the fingerprint sensor when the fingerprint sensor is non-loaded and obtain at least two frames of data output by the fingerprint sensor when a finger presses different positions on the sensing part; and

the processing unit comprises;

a selection subunit, configured to select from the at least two frames of data a corresponding maximum value corresponding to each sensing unit; and

a second calculation subunit, configured to calculate the new correction coefficient of the sensing unit;

k_new=corresponding maximum value−

data output in a non-loaded condition, and b_new=data output in a non-loaded condition.

7. The fingerprint sensor according to claim 6, wherein the correction unit is specifically configured to:

calculate

8. A correction method for a fingerprint sensor, the fingerprint sensor comprising a sensing part to be touched by a finger, the sensing part comprising a plurality of sensing units, wherein the method comprises steps of:

S10;

when correction starts, sensing a fingerprint signal and obtaining first data output by each sensing unit;

S20;

calculating, according to a mathematical model, a new correction coefficient of the corresponding sensing unit by using the first data; and

S30;

correcting, according to the new correction coefficient, second data output by the corresponding sensing unit.

9. The correction method according to claim 8, wherein after step S20 but before step S30, the method further comprises:

if an old correction coefficient is stored in the fingerprint sensor, replacing the old correction coefficient with the new correction coefficient, or with a weighted sum of the new correction coefficient and the old correction coefficient.

10. The correction method according to claim 9, wherein before step S10, the method further comprises:

determining whether a correction condition is satisfied, and executing S10 if the correction condition is satisfied, wherein the correction condition comprises;

the fingerprint sensor is enabled for the first time, a preset correction time is reached, a correction instruction is received, or an effect of correction by means of the old correction coefficient does not reach a designated requirement.

11. The correction method according to claim 10, wherein the effect of correction by means of the old correction coefficient is evaluated by using an image smoothness or a root-mean-square error of data that is output by all the sensing units and corrected by means of the old correction coefficient, and if the an image smoothness or the root-mean-square error is greater than a preset threshold, the designated requirement is not reached.

12. The correction method according to claim 8, wherein step S20 specifically comprises:

calculating, according to the mathematical model, a new correction coefficient of the corresponding sensing unit by using the first data and the old correction coefficient of the corresponding sensing unit,

13. The correction method according to claim 8, wherein

step S10 specifically comprises:

obtaining a frame of data output by the sensing unit when the fingerprint sensor is non-loaded; and

obtaining at least two frames of data output by the sensing unit when a finger presses different positions on the sensing part of the fingerprint sensor; and

step S20 comprises;

selecting a corresponding maximum value corresponding to each sensing unit from the at least two frames of data; and

calculating the new correction coefficient of the sensing unit;

k_new=corresponding maximum value−

data output in a non-loaded condition, and b_new=data output in a non-loaded condition.

14. The correction method according to claim 13, wherein step S30 specifically comprises:

correcting the second data according to a formula