Fingerprint sensor and method of driving the same

• US 10,311,275 B2
• Filed: 02/03/2017
• Issued: 06/04/2019
• Est. Priority Date: 08/24/2016
• Status: Active Grant

• Current Assignee: Samsung Electronics Co. Ltd.
• Original Assignee: Samsung Electronics Co. Ltd.
• Inventors: Hong, Seogwoo, Kim, Dongkyun
• Primary Examiner(s): Werner, Brian
• Application Number:
  US15/424,130
• Publication Number:
  US 20180060636A1
• Time in Patent Office: 851 Days
• CPC Class Codes: G06V 40/1306 non-optical, e.g. ultrasonic or capacitive sensing
• CPC Class Codes: G06V 40/1365 Matching; Classification

Abstract

Sensing sensitivity of a fingerprint sensor may be enhanced by grouping driving electrodes and driving groups. A processor of the fingerprint sensor may calculate mutual capacitance at each node on a touchpad from gross mutual capacitances in areas including a plurality of channels.

Claims

1. A fingerprint sensor comprising:

a touchpad including a plurality of driving electrodes and a plurality of sensing electrodes, the plurality of sensing electrodes being disposed in a direction intersecting with the plurality of driving electrodes, the plurality of driving electrodes being divided into a plurality of driving groups;

a driver configured to sequentially apply a driving signal to each of the plurality of driving groups;

a signal measurement unit configured to measure electrical signals generated from the plurality of sensing electrodes in response to the driving signal; and

a processor configured to calculate mutual capacitance based on the electrical signals measured by the signal measurement unit, at each of a plurality of nodes at which each of the plurality of driving electrodes intersects with each of the plurality of sensing electrodes, by assigning different weights to gross mutual capacitances measured in each of the plurality of driving groups, based on a location of each of the plurality of nodes.

2. The fingerprint sensor of claim 1, wherein the signal measurement unit is further configured to sequentially measure the electrical signals output from each of the plurality of sensing electrodes.

3. The fingerprint sensor of claim 1,

wherein the signal unit is further configured to group the plurality of sensing electrodes into a plurality of sensing groups and sequentially measure the electrical signals output from each of the plurality of sensing groups, and each of the plurality of sensing groups comprises at least two sensing electrodes,

wherein order numbers of the sensing electrodes included in each of the plurality of sensing groups are sequentially changed in accordance with an order number of each of the plurality of sensing groups.

4. The fingerprint sensor of claim 1, wherein the signal measurement unit is further configured to group the plurality of sensing electrodes into the plurality of sensing groups and sequentially measure the electrical signals output from each of the plurality of sensing groups.

5. The fingerprint sensor of claim 1, further comprising an electrode configured to apply a predetermined fixed voltage to at least two channels among a plurality of channels formed by the plurality of driving electrodes and the plurality of sensing electrodes on the touchpad.

6. The fingerprint sensor of claim 5, wherein channels receiving the predetermined fixed voltage are on a periphery of the touchpad.

7. The fingerprint sensor of claim 5, wherein the processor is further configured to calculate the mutual capacitance of a channel adjacent to the channels receiving the predetermined fixed voltage, based on the gross mutual capacitance in an area which includes the channels receiving the predetermined fixed voltage and the channel adjacent to the channels receiving the predetermined fixed voltage.

8. A method of driving a fingerprint sensor including a plurality of driving electrodes and a plurality of sensing electrodes disposed in a direction intersecting with the plurality of the driving electrodes, the plurality of driving electrodes being divided into a plurality of driving groups, the method comprising:

sequentially applying a driving signal to each of the plurality of driving groups; and

measuring electrical signals generated from the plurality of sensing electrodes in response to the driving signal,

calculating mutual capacitance based on the measured electrical signal, at each of a plurality of nodes at which each of the plurality of driving electrodes intersects with each of the plurality of sensing electrodes, by assigning different weights to gross mutual capacitances measured in each of the plurality of driving groups, based on a location of the plurality of nodes.

9. The method of claim 8,

wherein the measuring the electrical signals comprises grouping the plurality of sensing electrodes into a plurality of sensing groups and sequentially measuring the electrical signals output from each of the plurality of sensing groups.

10. The method of claim 8, the measuring the electrical signal comprises grouping the plurality of sensing electrodes into the plurality of sensing groups and sequentially measuring the electrical signal output from each of the plurality of sensing groups.

11. The method of claim 8, further comprising applying a predetermined fixed voltage to at least two channels among a plurality of channels formed by the plurality of driving electrodes and the plurality of sensing electrodes.

12. The method of claim 11, the calculating the mutual capacitance comprises calculating the mutual capacitance at a channel adjacent to a channel receiving the predetermined fixed voltage, based on the gross mutual capacitance in an area which includes the channel receiving the predetermined fixed voltage and the channel adjacent to the channel receiving the predetermined fixed voltage.

13. A fingerprint sensor comprising:

a touchpad including a plurality of driving electrodes and a plurality of sensing electrodes, the plurality of sensing electrodes being disposed in a direction intersecting with the plurality of driving electrodes, the plurality of driving electrodes being divided into a plurality of driving groups;

a driver configured to sequentially apply a driving signal to each of the plurality of driving groups;

a signal measurement unit configured to group the plurality of sensing electrodes into a plurality of sensing groups that partially overlap with each other, and measure, in response to the drive signal, gross mutual capacitances from each of the plurality of sensing groups that comprises a same sensing node at which one of the plurality of driving electrodes intersects with one of the plurality of sensing electrodes; and

a processor configured to calculate a mutual capacitance of the sensing node by averaging the gross mutual capacitances measured from each of the plurality of sensing groups.