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

1. A fingerprint motion tracking apparatus, comprising:

a first linear sensor array configured to sense features of a fingerprint along a first axis of finger motion and configured to repeatedly sense at least two line segments of fingerprint data, the first linear sensor array including a plurality of substantially contiguous sensing elements configured to capture segments of image data;

a second linear sensor array configured to sense features of a fingerprint along a second axis of finger motion and configured to repeatedly sense at least two line segments of fingerprint data, the second linear sensor array including a plurality of substantially contiguous sensing elements configured to capture segments of image data, wherein the first linear sensor array is non-parallel with respect to the second linear sensor array;

a buffer configured to receive and store image data from each of the first and the second linear sensor arrays; and

a processing element configured to generate fingerprint motion data for use in navigation, wherein the processing element uses image data from the first linear sensor array to determine velocity along the first axis of finger motion, and uses image data from the second linear sensor array to determine velocity along the second axis of finger motion,

wherein the first linear sensor array is configured to sense a first set of features of a fingerprint along the first axis of finger motion and to generate a first set of image data captured by a plurality of substantially contiguous pixels of the first linear sensor array, and is also configured to subsequently sense a second set of features of the fingerprint along the first axis of finger motion and to generate a second set of image data captured by the plurality of substantially contiguous pixels of the first linear sensor array, and

wherein the processing element is configured to compare the first and the second sets of image data to determine the distance traveled by the fingerprint over a time interval, and

wherein the distance and the 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 first linear sensor array.

2. An apparatus according to claim 1 , wherein the processing element is configured to generate motion data based on at least two sensed 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 fingerprint motion data further includes directional data.

5. 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 fingerprint motion data to assemble contiguous image portions.

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

sensing at least two consecutive overlapping line segments of a fingerprint image along a first axis of motion of a fingerprint surface;

sensing at least two consecutive overlapping line segments of the fingerprint image along a second axis of motion of the fingerprint surface;

storing digital data corresponding to the at least two consecutive overlapping line segments of the fingerprint image for each of the first and the second axes of motion; and

processing the digital data to generate fingerprint motion data and navigation data, wherein generating the fingerprint motion data comprises determining a velocity along each of the first and the second axes of motion

comparing digital data corresponding to a first line segment with digital data corresponding to a second line segment, wherein the first line segment comprises a first series of fingerprint image features and the second line segment comprises a subsequently sensed series of fingerprint image features;

determining the amount of shift between the first line segment and the second line segment to determine the distance traveled by the fingerprint across a sensor;

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

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 first line segment and the sensing of the second line segment; and

generating navigation data based on the distance and the velocity, for use in navigating an object relative to the fingerprint motion.

7. A method according to claim 6 , further comprising the steps of:

estimating the distance traveled by the fingerprint surface with respect to the sensor surface by multiplying the amount of 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 first line segment and the sensing of the second line segment.

8. 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, by a processor in communication with the linear image sensor arrays, 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, by the processor, which of the linear image sensor arrays produced the highest similarity match score to represent the principal axis of motion;

determining, by the processor, an amount of 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;

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

determining a linear 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 of motion 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 a vector sum of the pixels on the secondary axis and the pixels on the primary axis.

9. The method according to claim 8 , further comprising the steps of:

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

10. A method according to claim 8 , further comprising the steps of:

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

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

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

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

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

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

means for generating by a processor in communication with a sensor array 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 an amount of 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;

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

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;

means for determining an amount of 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, the final velocity and direction is computed as the vector sum of the pixels on the secondary axis and the pixels on the primary axis; and

processing means for generating navigation data.

12. A system according to claim 11 , further comprising means for producing navigation data using motion and direction data to assemble contiguous image portions.

13. A system according to claim 12 , further comprising:

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

14. A system according to claim 12 , 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.