FINGER SENSING DEVICE WITH MULTIPLE CORRELATORS AND ASSOCIATED METHODS

• US 20070292007A1
• Filed: 06/19/2007
• Published: 12/20/2007
• Est. Priority Date: 06/19/2006
• Status: Active Grant

• Current Assignee: Apple Inc.
• Original Assignee: Authentec Incorporated State of Incorporation Delaware
• Inventors: NEIL, James
• Granted Patent: US 8,081,805 B2
• Time in Patent Office: Days
• 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

A finger sensing device may include a finger sensing area to receive a user'"'"'s finger moved in a sliding motion, and a controller cooperating with the finger sensing area for generating successive image samples. Moreover, the controller may also generate the displacement estimate of the user'"'"'s finger by at least performing a plurality of different image sample correlations between at least one pair of image samples, and cross-verifying results of the plurality of different image sample correlations.

Claims

1. A finger sensing device comprising:

a finger sensing area to receive a user'"'"'s finger moved in a sliding motion; and

a controller cooperating with said finger sensing area for

generating successive image samples, and

generating a displacement estimate of the user'"'"'s finger by at least performing a plurality of different image sample correlations between at least one pair of image samples, and cross-verifying results of the plurality of different image sample correlations.

5. The finger sensing device according to claim 1 wherein said controller, for each different image sample correlation, generates respective rankings for different possible displacements;

and wherein said controller performs the cross-verifying based upon the rankings for the different possible displacements.

6. The finger sensing device according to claim 1 wherein said controller further determines a velocity of the user'"'"'s finger based upon the displacement estimate.

7. The finger sensing device according to claim 6 wherein said controller further performs a navigation function based upon the velocity of the user'"'"'s finger.

8. The finger sensing device according to claim 1 wherein said controller enters a coast mode based upon a failure of the cross-verifying.

9. The finger sensing device according to claim 1 wherein each displacement comprises at least one of a translational displacement and a rotational displacement.

10. The finger sensing device according to claim 1 wherein said finger sensing area comprises an array of electric field sensing pixels.

2. The finger sensing device according to claim I wherein each image sample comprises a plurality of pixels;

and wherein the plurality of different image correlations comprises a first image correlation that generates a first correlation score based upon a number of matched pixels and a number of mismatched pixels.

3. The finger sensing device according to claim 2 wherein the first image correlation is based upon the number of matched pixels minus a weighted number of the mismatched pixels.

4. The finger sensing device according to claim 2 wherein the plurality of different image correlations further comprises a second image correlation that generates a second correlation score based upon the number of matched pixels from a predetermined overlap area.

11. An electronic device comprising:

a housing;

a display carried by said housing;

a finger sensing area carried by said housing to receive a user'"'"'s finger moved in a sliding motion; and

a controller cooperating with said finger sensing area for

generating successive image samples, and

generating a displacement estimate of the user'"'"'s finger by at least performing a plurality of different image sample correlations between at least one pair of image samples, and cross-verifying results of the plurality of different image sample correlations.

12. The electronic device according to claim 11 wherein each image sample comprises a plurality of pixels;

and wherein the plurality of different image correlations comprises a first image correlation that generates a first correlation score based upon a number of matched pixels and a number of mismatched pixels.

13. The electronic device according to claim 12 wherein the first image correlation is based upon the number of matched pixels minus a weighted number of the mismatched pixels.

14. The electronic device according to claim 12 wherein the plurality of different image correlations further comprises a second image correlation that generates a second correlation score based upon the number of matched pixels from a predetermined overlap area.

15. The electronic device according to claim 11 wherein said controller, for each different image sample correlation, generates respective rankings for different possible displacements;

and wherein said controller performs the cross-verifying based upon the rankings for the different possible displacements.

16. The electronic device according to claim 11 wherein said controller further determines a velocity of the user'"'"'s finger based upon the displacement estimate.

17. The electronic device according to claim 16 wherein said controller further performs a navigation function based upon the velocity of the user'"'"'s finger.

18. The electronic device according to claim 11 wherein said controller enters a coast mode based upon a failure of the cross-verifying.

19. A method of generating a displacement estimate of the user'"'"'s finger as the user'"'"'s finger is moved in a sliding motion over a finger sensing area, the method comprising:

generating successive image samples; and

generating the displacement estimate of the user'"'"'s finger by at least

performing a plurality of different image sample correlations between at least one pair of image samples, and

cross-verifying results of the plurality of different image sample correlations.

20. The method according to claim 19 wherein each image sample comprises a plurality of pixels;

and

wherein the plurality of different image correlations comprises a first image correlation that generates a first correlation score based upon a number of matched pixels and a number of mismatched pixels.

21. The method according to claim 20 wherein the first image correlation is based upon the number of matched pixels minus a weighted number of the mismatched pixels.

22. The method according to claim 20 wherein the plurality of different image correlations further comprises a second image correlation that generates a second correlation score based upon the number of matched pixels from a predetermined overlap area.

23. The method according to claim 19 wherein, for each different image sample correlation, generating respective rankings for different possible displacements;

and performing the cross-verifying based upon the rankings for the different possible displacements.

24. The method according to claim 19 further comprising entering a coast mode based upon a failure of the cross-verifying.