FINGER BIOMETRIC SENSING DEVICE INCLUDING ERROR COMPENSATION CIRCUITRY AND RELATED METHODS

• US 20130315451A1
• Filed: 05/03/2013
• Published: 11/28/2013
• Est. Priority Date: 05/04/2012
• Status: Active Grant

• Current Assignee: Apple Inc.
• Original Assignee: Apple Inc.
• Inventors: MINTEER, Gregory T., DOOLEY, Jerry G., Landy, Patrick J., SETLAK, Dale R., GOZZINI, Giovanni, FRANZA, Gordon S.
• Granted Patent: US 9,390,307 B2
• Time in Patent Office: Days
• US Class Current: 382/124
• CPC Class Codes: G06F 3/038 Control and interface arrangements therefor, e.g. drivers or device-embedded control circuitry
• CPC Class Codes: G06V 40/1306 non-optical, e.g. ultrasonic or capacitive sensing
• CPC Class Codes: G06V 40/1329 Protecting the fingerprint sensor against damage caused by the finger
• CPC Class Codes: G06V 40/1365 Matching; Classification
• CPC Class Codes: H03G 3/3084 in receivers or transmitters for electromagnetic waves other than radiowaves, e.g. lightwaves H03G3/32, H03G3/34 take precedence

Abstract

A finger biometric sensing device may include an array of finger biometric sensing pixel electrodes and a gain stage coupled to the array of finger biometric sensing pixel electrodes. The finger biometric sensing device may also include error compensation circuitry that may include a memory capable of storing error compensation data. The error correction circuitry may also include a digital-to-analog converter (DAC) cooperating with the memory and coupled to the gain stage and capable of compensating for at least one error based upon the stored error compensation data.

Claims

1. A finger biometric sensing device comprising:

an array of finger biometric sensing pixel electrodes;

at least one gain stage coupled to said array of finger biometric sensing pixel electrodes; and

error compensation circuitry comprising

a memory capable of storing error compensation data, and

a digital-to-analog converter (DAC) cooperating with said memory and coupled to said at least one gain stage and capable of compensating for at least one error based upon the stored error compensation data.

2. The finger biometric sensing device according to claim 1 wherein said memory is capable of storing error compensation data to account for tilt errors.

3. The finger biometric sensing device according to claim 1 further comprising a dielectric layer over said array of finger biometric sensing pixel electrodes;

wherein said dielectric layer has a non-uniform thickness; and

wherein said memory is capable of storing error compensation data to account for the non-uniform thickness of said dielectric layer.

4. The finger biometric sensing device according to claim 1 wherein said memory is capable of storing error compensation data to account for fixed pattern noise errors.

5. The finger biometric sensing device according to claim 1 wherein said memory is capable of storing error compensation data to account for a gain stage offset error.

6. The finger biometric sensing device according to claim 1 wherein said at least one gain stage comprises a plurality thereof coupled together in series and defining a summing node between a pair of adjacent ones of said plurality of gain stages;

and wherein said DAC is coupled to said summing node.

7. The finger biometric sensing device according to claim 1 further comprising:

an output analog-to-digital (ADC) coupled to said at least one gain stage and having a dynamic range; and

control circuitry capable of adjusting said at least one gain stage so that an output thereof is within the dynamic range of said output ADC.

8. The finger biometric sensing device according to claim 1 further comprising switching circuitry coupled to said array of finger biometric sensing pixel electrodes and said at least one gain stage capable of sequentially generating output data for adjacent regions of said array of finger biometric sensing pixel electrodes.

9. The finger biometric sensing device according to claim 1 further comprising a finger coupling electrode adjacent said array of finger biometric sensing pixel electrodes, and a voltage generator coupled to said finger coupling electrode.

10. A finger biometric sensing device comprising:

an array of finger biometric sensing pixel electrodes;

a finger coupling electrode adjacent said array of finger biometric sensing pixel electrodes;

a voltage generator coupled to said finger coupling electrode;

at least one gain stage coupled to said array of finger biometric sensing pixel electrodes;

error compensation circuitry comprising

a memory capable of storing error compensation data, and

a digital-to-analog converter (DAC) cooperating with said memory and coupled to said at least one gain stage and capable of compensating for at least one error based upon the stored error compensation data;

an output analog-to-digital (ADC) coupled to said at least one gain stage and having a dynamic range; and

control circuitry capable of adjusting said at least one gain stage so that an output thereof is within the dynamic range of said output ADC.

11. The finger biometric sensing device according to claim 10 wherein said memory is capable of storing error compensation data to account for tilt errors.

12. The finger biometric sensing device according to claim 10 further comprising a dielectric layer over said array of finger biometric sensing pixel electrodes;

wherein said dielectric layer has a non-uniform thickness; and

wherein said memory is capable of storing error compensation data to account for the non-uniform thickness of said dielectric layer.

13. The finger biometric sensing device according to claim 10 wherein said memory is capable of storing error compensation data to account for fixed pattern noise errors.

14. The finger biometric sensing device according to claim 10 wherein said memory is capable of storing error compensation data to account for a gain stage offset error.

15. The finger biometric sensing device according to claim 10 wherein said at least one gain stage comprises a plurality thereof coupled together in series and defining a summing node between a pair of adjacent ones of said plurality of gain stages;

and wherein said DAC is coupled to said summing node.

16. The finger biometric sensing device according to claim 10 further comprising switching circuitry coupled to said array of finger biometric sensing pixel electrodes and said at least one gain stage capable of sequentially generating output data for adjacent regions of said array of finger biometric sensing pixel electrodes.

17. A method of error compensation in a finger biometric sensing device comprising an array of finger biometric sensing pixel electrodes and at least one gain stage coupled to the array of finger biometric sensing pixel electrodes, the method comprising:

using error compensation circuitry comprising a memory capable of storing error compensation data and a digital-to-analog converter (DAC) cooperating with the memory and coupled to the at least one gain stage to compensate for at least one error based upon the stored error compensation data.

18. The method according to claim 17 wherein the memory is capable of storing error compensation data to account for tilt errors.

19. The method according to claim 17 further comprising a dielectric layer over the array of finger biometric sensing pixel electrodes;

wherein the dielectric layer has a non-uniform thickness; and

wherein the memory is capable of storing error compensation data to account for the non-uniform thickness of the dielectric layer.

20. The method according to claim 17 wherein the memory is capable of storing error compensation data to account for fixed pattern noise errors.

21. The method according to claim 17 wherein the memory is capable of storing error compensation data to account for a gain stage offset error.

22. The method according to claim 17 wherein the at least one gain stage comprises a plurality thereof coupled together in series and defining a summing node between a pair of adjacent ones of the plurality of gain stages;

and wherein the DAC is coupled to the summing node.

23. The method according to claim 17 further comprising using control circuitry to adjust the at least one gain stage so that an output thereof is within a dynamic of an output analog-to-digital (ADC) coupled to the at least one gain stage and having a dynamic range.

24. The method according to claim 17 further comprising using switching circuitry coupled to the array of finger biometric sensing pixel electrodes and the at least gain stage capable to sequentially generate output data for adjacent regions of the array of finger biometric sensing pixel electrodes.