Sensor pixel circuitry for fingerprint identification

Patent metadata

Field	Value
Publication number	US-10049253-B2
Application number	US-201615237019-A
Country	US
Kind code	B2
Filing date	Aug 15, 2016
Priority date	Oct 13, 2014
Publication date	Aug 14, 2018
Grant date	Aug 14, 2018

Abstract

In one aspect, a fingerprint sensor device for fingerprint detection includes an array of sensor pixels to capacitively couple with a touched portion of a finger to form an array of fingerprint associated capacitors having capacitive values indicative of a fingerprint. Each sensor pixel includes an output terminal configured to output an output signal that indicates a local capacitive coupling with the touched portion of the finger as part of fingerprint data for fingerprint detection; a capacitive sensing layer including an electrically conductive material that can be capacitively coupled to a local part of the touched portion of the finger, forming a fingerprint associated capacitor, the capacitive sensing layer operable to be coupled to the output terminal to cause the output signal; an integrated circuit layout layer that is electrically conductive; a fingerprint voltage generator; and a layout voltage generator.

First claim

What is claimed is:

1. A fingerprint sensor device for fingerprint detection, comprising:
an array of sensor pixels configured to capacitively couple with a touched portion of a finger to form an array of fingerprint associated capacitors having capacitive values indicative of a fingerprint,
each sensor pixel including:
an output terminal configured to output an output signal that indicates a local capacitive coupling with the touched portion of the finger as part of fingerprint data for fingerprint detection;
a capacitive sensing layer including an electrically conductive material that can be capacitively coupled to a local part of the touched portion of the finger, forming a fingerprint associated capacitor, the capacitive sensing layer operable to be coupled to the output terminal to cause the output signal;
an integrated circuit layout layer that is electrically conductive and is capacitively coupled to a ground terminal, forming a layout associated capacitor, the layout layer operable to be coupled to the output terminal;
a fingerprint voltage generator electrically coupled to supply power to the capacitive sensing layer to generate a fingerprint voltage to charge the fingerprint associated capacitor; and
a layout voltage generator electrically coupled to supply power to the integrated circuit layout layer to generate a layout voltage to charge the layout associated capacitor.

2. The fingerprint sensor device of claim 1 , comprising:
fingerprint switching circuitry configured to switch between electrically connecting the capacitive sensing layer to the fingerprint voltage generator and the output terminal to selectively charge the fingerprint associated capacitor using the fingerprint voltage; and
layout switching circuitry configured to switch between electrically connecting the integrated circuit layout layer to the layout voltage generator and the output terminal to selectively charge the layout associated capacitor using the layout voltage.

3. The fingerprint sensor device of claim 2 , wherein the fingerprint switching circuitry includes:
a charging switch electrically connected between the fingerprint voltage generator and the capacitive sensing layer to selectively charge the fingerprint associated capacitor during a charging period; and
a sensing switch electrically connected between the capacitive sensing layer and the output terminal to selectively sense a signal associated with the charged fingerprint associated capacitor during a sensing period different from the charging period.

4. The fingerprint sensor device of claim 3 , wherein during the charging period, the charging switch is turned on, and the sensing switch is turned off; during the sensing period, the charging switch is turned off, and the sensing switch is turned on.

5. The fingerprint sensor device of claim 2 , wherein the layout switching circuitry includes:
a charging switch electrically connected between the layout voltage generator and the integrated circuit layout layer to selectively charge the layout associated capacitor during a charging period; and
a sensing switch electrically connected between the integrated circuit layout layer and the output terminal to selectively sense a signal associated with the charged layout associated capacitor during a sensing period different from the charging period.

6. The fingerprint sensor device of claim 5 , wherein during the charging period, the charging switch is turned on, and the sensing switch is turned off;
during the sensing period, the charging switch is turned off, and the sensing switch is turned on.

7. The fingerprint sensor device of claim 1 , wherein the capacitive sensing layer is configured to form with a surface of a finger two opposing conductive electrodes of the finger associated capacitor.

8. The fingerprint sensor device of claim 1 , wherein the fingerprint voltage generator and the layout voltage generator are configured to vary the generated fingerprint and layout voltages independent of each other.

9. The fingerprint sensor device of claim 1 , wherein each of the fingerprint voltage generator and the layout voltage generator include a digital to analog converter to vary the generated fingerprint and layout voltages.

10. The fingerprint sensor device of claim 1 , comprising:
an integrator electrically coupled to the output terminal connected to the fingerprint associated capacitor and the layout associated capacitor to store electrical charges associated with the charged fingerprint associated capacitor responsive to a touch by a finger of a user.

11. The fingerprint sensor device of claim 10 , wherein the integrator comprises:
a reference voltage generator configured to generate a reference voltage;
an amplifier, comprising:
a positive input terminal electrically coupled to the reference voltage generator to receive the reference voltage;
a negative input terminal electrically coupled to the output terminal connected to the fingerprint associated capacitor and the layout associated capacitor; and
an output terminal of the amplifier;
an integrating capacitor electrically coupled between the negative input terminal and the output terminal of the amplifier; and
a reset switch electrically coupled between the negative input terminal and the output terminal of the amplifier.

12. The fingerprint sensor device of claim 11 , wherein the reference voltage generator includes a digital to analog converter to vary the generated reference voltage.

13. The fingerprint sensor device of claim 1 , wherein the output terminal connected to the fingerprint associated capacitor and the layout associated capacitor is configured to generate the output signal associated with a ridge or a valley of a finger.

14. The fingerprint sensor device of claim 1 , wherein
the array of sensor pixels are arranged to form groups of electrically connected sensor pixel circuitry operable to capture fingerprint pattern of the touched portion of the finger, each sensor pixel circuitry in the array comprises:
a separate analog to digital converter electrically coupled to each group of electrically connected sensor pixel circuitry;
a separate enable switch electrically coupled between each sensor pixel circuitry in a corresponding group of electrically connected sensor pixel circuitry and a corresponding analog to digital converter; and
a control module electrically coupled to each sensor pixel circuitry in the array, the control module configured to generate a control signal to control each sensor pixel circuitry in the array.

15. The fingerprint sensor device of claim 14 , wherein:
the control module is configure to generate the control signal to control each sensor pixel circuitry in the array to integrate the output signal in each sensor pixel circuitry in the array in parallel.

16. A fingerprint sensor device for fingerprint detection, the fingerprint sensor device comprising:
an output terminal configured to output an output signal indicative of capacitive coupling with a touched portion of a finger as a part of fingerprint data for fingerprint detection;
a sensor electrode including electrically conductive material that can be capacitively coupled to the touched portion of the finger, forming a fingerprint associated capacitor, the capacitive sensing layer operable to be coupled to the output terminal to cause the output signal;
a pair of substantially identical integrated circuit layout electrodes that are electrically conductive, wherein:
one of the pair of substantially identical integrated circuit layout electrodes is capacitively coupled to th

Assignees

• Shenzhen Goodix Tech Co Ltd

Inventors

• Yang Mengda
• Chao Kuohao
• Zhan Chang

Classifications

• G06K9/00053

  Physics · mapped topic

• G06K9/0002 Primary

  Physics · mapped topic

• G06V40/63

  by static guides · CPC title

• G06V40/1306 Primary

  non-optical, e.g. ultrasonic or capacitive sensing · CPC title

• G06V40/1329

  Protecting the fingerprint sensor against damage caused by the finger · CPC title