Apparatus and method for culling substantially redundant data in fingerprint sensing circuits

• US 8,600,122 B2
• Filed: 01/15/2009
• Issued: 12/03/2013
• Est. Priority Date: 01/15/2009
• Status: Active Grant

• Current Assignee: Synaptics Incorporated
• Original Assignee: Validity Sensors Incorporated (Synaptics Incorporated)
• Inventors: Dean, Gregory Lewis, Thompson, Erik Jonathon, Schwab, Frank, Erhart, Richard Alexander
• Primary Examiner(s): Li, Ruiping
• Application Number:
  US12/354,680
• Publication Number:
  US 20100177940A1
• Time in Patent Office: 1,783 Days
• Field of Search: 382/124, 382/125, 382/115, 382/181
• US Class Current: 382/124
• CPC Class Codes: G06V 40/1335 Combining adjacent partial images (e.g. slices) to create a composite input or reference pattern; Tracking a sweeping finger movement

Abstract

An apparatus for culling substantially redundant data in a fingerprint sensing circuit is disclosed in one embodiment of the invention as including an input module, a storage module, a comparator module, and a determination module. The input module may receive sets of data samples from an array of fingerprint sensing elements. The sets of data samples may be stored by the storage module. The comparator module may calculate a difference between each data sample from a first-received set, and a corresponding data sample from a second-received set. The determination module may count the number of difference values that exceed a predetermined difference limit, and identify the second set of data samples as redundant if the number of difference values counted is less than a pre-set count limit.

Claims

1. An apparatus comprising:

a computing device configured to;

receive a reference set of data samples, each data sample in the reference set of data samples being an output of a respective fingerprint image sensing element in a one dimensional linear array of fingerprint image sensing elements, oriented to capture one line of a fingerprint image at a time, each line later used to reconstruct an identifying fingerprint image and to receive a next successive set of data samples, each data sample in the next successive set of data samples being a subsequent output of the respective fingerprint image sensing element in the one dimensional linear array of fingerprint sensing elements;

determine the existence of a difference between a data sample from the reference set and a corresponding data sample from the next successive set, which difference exceeds a selected threshold value, for each data sample from the reference set and the corresponding data sample from the next successive set;

count the number of times the difference exceeds the threshold in comparing the reference set to the next successive set; and

identify the next successive set of data samples as redundant when the number is less than a selected count.

2. The apparatus of claim 1, wherein the computing device is configured to store the reference set of data samples in a first data buffer and store the next successive set of data samples in a second data buffer.

3. The apparatus of claim 2, wherein the computing device is configured to overwrite the reference set of data samples in the first data buffer with the next subsequent set of data samples when the number is greater than the selected count.

4. The apparatus of claim 3, wherein the computing device is configured to overwrite the next successive set of data samples in the second data buffer with a further next successive set of data samples.

5. The apparatus of claim 1, wherein the computing device is configured to attach a header to the next successive set of data samples.

6. The apparatus of claim 5, wherein the header identifies the next successive set of data samples as redundant where the number is less than the selected count.

7. The apparatus of claim 6, wherein the computing device is configured to transmit the header to a host system in the event the number is less than the selected count.

8. The apparatus of claim 1, wherein the computing device is configured to discard the next successive set of data samples when the number is less than the selected count.

9. A method comprising:

receiving, via a computing device, a reference set of data samples, each data sample in the reference set of data samples being an output of a respective fingerprint image sensing element in a one dimensional linear array of fingerprint image sensing elements, oriented to capture one line of a fingerprint image at a time, each line later used to reconstruct an identifying fingerprint image;

receiving, via a computing device, a next successive set of data samples, each data sample in the next successive set of data samples being a subsequent output of a respective fingerprint image sensing element in the one-dimensional linear array of fingerprint image sensing elements;

calculating, via a computing device, a difference between a data sample from the reference set and a corresponding data sample from the next successive set and providing a plurality of difference values, for each data sample from the reference set and the corresponding data sample from the next successive set;

counting, via a computing device, the number of difference values that exceed a selected threshold, for each data sample from the reference set and the corresponding data sample from the next successive set; and

identifying the next successive set of data samples as redundant when the number is less than a selected count.

10. The method of claim 9, further comprising storing the reference set of data samples in a first data buffer and storing the next successive set of data samples in a second data buffer.

11. The method of claim 10, further comprising overwriting the reference set of data samples in the reference data buffer with the next successive set of data samples when the number is greater than the selected count.

12. The method of claim 11, further comprising overwriting the next successive set of data samples in the second data buffer with a further next successive set of data samples.

13. The method of claim 9, further comprising attaching a header to the next successive set of data samples, the header identifying the next successive set of data samples as redundant when the number is less than the selected count.

14. The method of claim 13, further comprising transmitting the header to a host system when the number is less than the selected count.

15. The method of claim 9, further comprising discarding the next successive set of data samples when the number is less than the selected count.

16. A system comprising:

a fingerprint sensor comprising one-dimensional linear array of fingerprint sensing elements;

a host system configured to receive sets of data samples from the fingerprint sensor;

and a sensor computing device configured to reduce the amount of substantially redundant sets of data samples data that is transmitted from the fingerprint sensor to the host system, the sensor computing device configured to;

receive a reference set of data samples from the one-dimensional linear array of fingerprint sensing elements, oriented to capture one line of a fingerprint image at a time, each line later used to reconstruct an identifying fingerprint image, and subsequently to receive a next successive set of data samples from the one-dimensional linear array of fingerprint sensing elements;

calculate a difference between each data sample from the reference set and a corresponding data sample from the next successive set and provide a plurality of difference values, for each data sample from the reference set and the corresponding data sample from the next successive set;

count the number of difference values that exceed a selected threshold, for each data sample from the reference set and the corresponding data sample from the next successive set; and

identify the next successive set of data samples as redundant when the number is less than a selected count.

17. The system of claim 16, wherein the sensor computing device is configured to discard the next successive set of data samples when the number is less than the selected count.

18. The system of claim 16, wherein the sensor computing device is configured to attach a header to the next successive set of data samples when the number is less than the selected count, the header identifying the next successive set of data samples as redundant.

19. A non-transitory machine readable medium storing instructions that, when executed by a computing device, cause the computing device to perform a method, the method comprising:

receiving a reference set of data samples, each data sample in the reference set of data samples being an output of a respective fingerprint image sensing element in a one dimensional linear array of fingerprint image sensing elements, oriented to capture one line of a fingerprint image at a time, each line later used to reconstruct an identifying fingerprint image, and a next successive set of data samples, each data sample in the next successive set of data samples being a subsequent output of the respective fingerprint image sensing element in the one dimensional linear array of fingerprint sensing elements;

determining the existence of a difference between each data sample from the reference set and a corresponding data sample from the next successive set, which difference that exceeds a selected threshold value;

counting the number of times the difference exceeds the threshold; and

identify the second set of data samples as redundant when the number is less than a selected count.

20. A biometric sensing system comprising:

a biometric sensor sensing a reference set of data samples, each data sample in the reference set of data samples being an output of a respective biometric image sensing element in a one dimensional linear array of biometric image sensing elements, oriented to capture one line of a biometric image at a time, each line later potentially to be used to reconstruct an identifying biometric image and to receive a next successive set of data samples, each data sample in the next successive set of data samples being a subsequent output of the respective biometric image sensing element in the one dimensional linear array of biometric sensing elements;

a computing device configured to determine the existence of a difference between a data sample from the reference set and a corresponding data sample from the next successive set, which difference exceeds a selected threshold value, for each data sample from the reference set and the corresponding data sample from the next successive set;

count the number of times the difference exceeds the threshold in comparing the reference set to the next successive set; and

identify the next successive set of data samples as redundant when the number is less than a selected count.