Method and apparatus for fingerprint motion tracking using an in-line array for use in navigation applications

• US 20080063245A1
• Filed: 09/11/2006
• Published: 03/13/2008
• Est. Priority Date: 09/11/2006
• Status: Active Grant

• Current Assignee: Synaptics Incorporated
• Original Assignee: Validity Sensors Incorporated (Synaptics Incorporated)
• Inventors: Geoffroy, David Joseph, Benkley, Fred George
• Granted Patent: US 8,165,355 B2
• Time in Patent Office: Days
• US Class Current: 382/124
• CPC Class Codes: G06F 2203/0338 Fingerprint track pad, i.e. fingerprint sensor used as pointing device tracking the fingertip image
• CPC Class Codes: G06F 3/03547 Touch pads, in which fingers can move on a surface
• CPC Class Codes: G06F 3/041 Digitisers, e.g. for touch screens or touch pads, characterised by the transducing means
• CPC Class Codes: G06F 3/0416 Control or interface arrangements specially adapted for digitisers
• 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

The invention provides an independent relative motion sensor for use in navigation operations using a fingerprint that do not require the power demanded by conventional devices. The independent relative motion sensor includes a linear array of sensing elements that captures a narrow string of data that is indicative of fingerprint features along a relatively narrow sample. This string of data is used to determine the velocity of travel for use in navigation operations. Using multiple sensors, motion and direction data can be computed and used to provide two-dimensional direction for navigating an object, such as a cursor on a monitor. The invention can be incorporated in an electronic device to provide improved navigation operations that demand less power.

Claims

1. A fingerprint motion tracking apparatus for use in navigation applications, comprising:

a linear sensor array configured to sense features of a fingerprint along an axis of finger motion, the linear sensor array including a plurality of substantially contiguous sensing elements configured to capture segments of image data;

a buffer configured to receive and store image data from the linear sensor array; and

a processing element configured to generate fingerprint motion data for use in navigation.

2. An apparatus according to claim 1, wherein the linear sensor array is configured to repeatedly sense at least two overlapping line segments of fingerprint data, and wherein the processor is configured to generate motion data based on at least two sensed overlapped line segments of fingerprint data and navigation data based on relative motion of a fingerprint relative to an object being navigated.

3. An apparatus according to claim 2, wherein the object being navigated is a cursor on a graphical user interface.

4. An apparatus according to claim 1, wherein the motion data includes velocity and directional data.

5. A fingerprint motion tracking apparatus according to claim 1, wherein the linear sensor array is configured to sense a first set of features of a fingerprint along an axis of finger motion and to generate a first set of image data captured by a plurality of substantially contiguous pixels of the sensor array and is also configured to subsequently sense a second set of features of the fingerprint along an axis of finger motion and to generate a second set of image data captured by a plurality of substantially contiguous pixels of the sensor array, and wherein the processing element is configured to compare first and second sets of image data to determine the distance traveled by the fingerprint over a time interval, and wherein the distance and time interval are used to calculate navigational data for navigating a cursor on a graphical user interface relative to the motion of a fingerprint across the sensor.

6. A fingerprint motion tracking apparatus according to claim 1, further comprising another linear sensor array configured to sense features of a fingerprint and to generate directional image data captured by a plurality of substantially contiguous pixels, wherein the processing element is configured to produce navigation data using the motion data to assemble contiguous image portions aligned along a second line of motion.

7. A fingerprint motion tracking apparatus according to claim 1, further comprising another linear sensor array aligned along another axis of finger motion and configured to sense features of a fingerprint and to generate directional image data captured by a plurality of substantially contiguous pixels for use in navigation operations of an object relative to the motion of a fingerprint across the linear sensors.

8. A fingerprint motion tracking apparatus according to claim 1, further comprising a plurality of linear sensor arrays configured to sense features of a fingerprint and to generate directional image data captured by a plurality of substantially contiguous pixels, wherein the processing element is configured to produce navigation data using the motion data to assemble contiguous image portions.

9. A method of tracking motion of a fingerprint with respect to a sensor for use in navigation operations, comprising:

sensing at least two consecutive overlapping line segments of a fingerprint image features located along an axis of motion of the fingerprint surface with respect to the sensor surface;

storing digital data corresponding to the line segments of a fingerprint image features sensed by the sensing elements; and

processing the digital data to generate fingerprint motion data and navigation data relative to an object being navigated.

10. A method according to claim 9, further comprising:

comparing digital data of a series of fingerprint image features with a subsequently sensed series of fingerprint image features;

determining the amount of shift between the series of fingerprint image features and the subsequently sensed series of fingerprint image features to determine the distance traveled by the fingerprint across a sensor; and

generating navigation data for use in navigating an object relative to the fingerprint motion.

11. A method according to claim 10, further comprising:

estimating the distance traveled by the fingerprint surface with respect to the sensor surface by multiplying the pixel shift detected between subsequent images times the physical distance of the image pixels in the sensor; and

computing the velocity of the fingerprint surface with respect to the sensor surface by dividing the estimated distance by the time expended between the sensing of the fingerprint image features and the subsequently sensed fingerprint image features.

12. A method according to claim 11, further comprising:

estimating the distance traveled by the fingerprint surface with respect to the sensor surface by multiplying the multiplying the pixel shift detected between subsequent images times the physical distance between pixels in the sensor; and

computing the velocity of the fingerprint surface with respect to the sensor surface by dividing the estimated distance by the time expended between the sensing of the fingerprint image features and the subsequently sensed fingerprint image features.

13. A method of tracking motion of a fingerprint with respect to a sensor for use in navigation operations, comprising:

collecting a time sequence of image samples from a linear sensory array, wherein each sample has a series of pixel values corresponding to substantially contiguous fingerprint image features;

generating a list of similarity match scores by comparing each image sample with a previous sample;

determining the pixel shift of two image samples having the highest similarity match score;

estimating the distance traveled by multiplying the number of pixels in an image sample times the physical distance between pixels;

computing a velocity estimate by dividing the estimated distance by the time expended between collecting the two samples with the highest match score navigating an object relative to the velocity estimate.

14. A method of tracking motion of a fingerprint with respect to a sensor for use in electronically navigating an object, comprising:

collecting a time sequence of images values from each of a plurality of linear image sensor arrays;

generating separate lists of similarity match scores for each linear image sensor array by comparing successively shifted versions of each image sample with a previous sample;

determining which linear sensor array produced the highest similarity match score to represent the principal axis of motion;

determining the pixel shift of the linear sensor array that has the highest similarity match score;

estimating the distance traveled along the principal axis by multiplying the number of pixels times the physical distance between pixels;

computing the velocity of the fingerprint surface with respect to the sensor surface; and

computing the relative movement of a fingerprint with respect to an object being navigated.

15. A method according to claim 14, further comprising:

determining the sensor array adjacent to the principal axis that had the next highest similarity score to represent the secondary axis of motion;

determining the pixel shift of the secondary axis with the highest similarity match score; and

if the pixel shift of the pixels on the secondary axis is less than the pixel shift of the pixels on the primary axis, computing the final velocity and direction as the vector sum of the pixels on the secondary axis and the pixels on the primary axis.

16. A method according to claim 15, further comprising:

generating navigation information for navigating an object relative to fingerprint motion using the final velocity and direction computed.

17. A fingerprint motion tracking apparatus for producing navigation information, comprising:

a linear sensor array configured to sense features of a fingerprint along an axis of finger motion, the linear sensor array including a plurality of substantially contiguous sensing elements configured to capture a plurality of segments of fingerprint image data;

a buffer configured to receive and store image data from the linear sensor array; and

a processing element configured to generate motion data for use in navigation operations.

18. A fingerprint motion tracking apparatus according to claim 17, further comprising at least one other linear sensor array configured to sense features of a fingerprint and to generate directional image data captured by a plurality of substantially contiguous pixels, wherein the processing element is configured to produce navigation data using the motion data to assemble contiguous image portions.

19. A fingerprint motion tracking system for producing navigation information, comprising:

means for sensing features of a fingerprint along an axis of finger motion, the with a plurality of substantially contiguous sensing elements configured to capture a plurality of segments of fingerprint image data;

buffer means for receiving and storing image data from the means for sensing features of a fingerprint; and

processing means for generating navigation data.

20. A system according to claim 19, further comprising means for producing navigation data using motion and direction data to assemble contiguous image portions.

21. A system according to claim 19, further comprising

means for generating separate lists of similarity match scores for each sensing element comparing successively shifted versions image samples with a previous sample;

means for determining which sensing element produced the highest similarity match score to represent a principal axis of motion;

means for determining the pixel shift of the sensing element that has the highest similarity match score;

means for estimating the distance traveled along the principal axis by multiplying the number of pixels times the physical distance between pixels;

means for computing the velocity of the fingerprint surface with respect to a sensing element; and

means for computing the relative movement of a fingerprint with respect to an object being navigated.

22. A system according to claim 21, further comprising:

means for determining which sensor array adjacent to a principal axis that had the next highest similarity score to represent the secondary axis of motion; and

means for determining the pixel shift of the secondary axis with the highest similarity match score;

wherein, if the pixel shift of the pixels on the secondary axis is less than the pixel shift of the pixels on the primary axis, computing the final velocity and direction as the vector sum of the pixels on the secondary axis and the pixels on the primary axis.

23. A system according to claim 22, further comprising:

means for generating navigation information for navigating an object relative to fingerprint motion using the final velocity and direction computed.