Tracking A Position In Relation To A Surface

• US 20080159088A1
• Filed: 12/05/2007
• Published: 07/03/2008
• Est. Priority Date: 12/29/2006
• Status: Active Grant

• Current Assignee: Marvell Asia Pte Limited (Marvell Technology Group Limited)
• Original Assignee: Marvell World Trade Limited (Marvell Technology Group Limited)
• Inventors: Simmons, Asher, Bledsoe, James D.
• Granted Patent: US 9,411,431 B2
• Time in Patent Office: Days
• US Class Current: 369/44.14
• CPC Class Codes: G06F 3/0317 in co-operation with a patterned surface, e.g. absolute position or relative movement detection for an optical mouse or pen positioned with respect to a coded surface
• CPC Class Codes: G06F 3/03543 Mice or pucks G06F3/03541 takes precedence
• CPC Class Codes: G06F 3/03544 having dual sensing arrangement, e.g. two balls or two coils used to track rotation of the pointing device

Abstract

A tracking device is provided for tracking a position of the tracking device in relation to a surface. The tracking device has a first optical sensor to capture a primary image of the surface. A second optical sensor is provided to capture a secondary image of the surface. A processor evaluates the primary and secondary images to determine a movement of the tracking device in relation to the surface.

Claims

1. A tracking device for tracking a position of the tracking device in relation to a surface, the tracking device comprising:

a first optical sensor to capture a primary image of the surface;

a second optical sensor to capture a secondary image of the surface, and

at least one processor to evaluate the primary and secondary images to determine a movement of the tracking device in relation to the surface.

2. A tracking device according to claim 1 wherein the first optical sensor is adapted to capture a first frame of the primary image at a first time and to capture a second frame of the primary image at a second time that is after the first time, wherein the second optical sensor is adapted to capture a first frame of the secondary image at a third time and to capture a second frame of the secondary image at a fourth time that is after the third time, and wherein the processor is adapted to perform the following to determine the position of the tracking device in relation to the surface:

(i) compare the second frame of the primary image to the first frame of the primary image to determine a displacement of the first optical sensor in a first dimension and a displacement of the first optical sensor in a second dimension that is different from the first dimension, and

(ii) compare the second frame of the secondary image to the first frame of the secondary image to determine a displacement of the second optical sensor in the first dimension and a displacement of the second optical sensor in the second dimension.

3. A tracking device according to claim 2, wherein the first time substantially coincides with the third time, and wherein the second time substantially coincides with the fourth time.

4. A tracking device according to claim 2, wherein the first and second times are interlaced with the third and fourth times.

5. A tracking device according to claim 1, wherein the processor is adapted to:

(i) determine that information related to the primary image is not sufficiently reliable to determine the position of the tracking device, and

(ii) evaluate information related to the secondary image to determine the movement of the tracking device absent further evaluation of the information related to the primary image.

6. A tracking device according to claim 1, wherein the first optical sensor is adapted to repeatedly capture frames of the primary image at a first rate, and wherein the second optical sensor is adapted to repeatedly capture frames of the secondary image at a second rate.

7. A tracking device according to claim 6, wherein the first and second rates are substantially the same.

8. A tracking device according to claim 6, wherein the first optical sensor is adapted to capture the frames of the secondary image in a phase-shifted relationship to the capture of the frames of the primary image.

9. A tracking device according to claim 6, wherein the processor is adapted to determine the position of the tracking device at a rate that is at least about twice the first rate.

10. A tracking device according to claim 1, wherein the processor is adapted to evaluate the primary and secondary images to determine a magnitude of rotation of the tracking device in relation to the surface.

11. A tracking device according to claim 1, wherein the processor is adapted to evaluate the primary and secondary images to determine a rotation point of the tracking device in relation to the surface.

12. A tracking device according to claim 1, wherein the first optical sensor is adapted to capture a primary image that comprises a two-dimensional image, and wherein the second optical sensor is adapted to capture a secondary image that comprises a two-dimensional image.

13. A tracking device for tracking a position of the tracking device in relation to a surface, the tracking device comprising:

a first optical sensor to capture a first frame of a primary image of the surface at a first time and to capture a second frame of the primary image at a second time that is after the first time;

a second optical sensor to capture a first frame of a secondary image of the surface at a third time and to capture a second frame of the secondary image at a fourth time that is after the third time; and

one or more processors to perform the following to determine a movement of the tracking device in relation to the surface;

(i) compare the second frame of the primary image to the first frame of the primary image to determine a displacement of the first optical sensor in a first dimension and a displacement of the first optical sensor in a second dimension that is different from the first dimension, and

(ii) compare the second frame of the secondary image to the first frame of the secondary image to determine a displacement of the second optical sensor in the first dimension and a displacement of the second optical sensor in the second dimension.

14. A method of tracking a position of an object in relation to a surface, the method comprising:

at the object, capturing a primary image of the surface;

at the object, capturing a secondary image of the surface; and

evaluating the primary and secondary images to determine a movement of the object in relation to the surface.

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

capturing a first frame of the primary image at a first time;

capturing a second frame of the primary image at a second time that is after the first time;

capturing a first frame of a secondary image at a third time;

capturing a second frame of the secondary image at a fourth time that is after the third time;

comparing the second frame of the primary image to the first frame of the primary image to determine a displacement of the first optical sensor in a first dimension and a displacement of the first optical sensor in a second dimension that is different from the first dimension; and

comparing the second frame of the secondary image to the first frame of the secondary image to determine a displacement of the second optical sensor in the first dimension and a displacement of the second optical sensor in the second dimension.

16. A method according to claim 15, wherein the first time substantially coincides with the third time, and wherein the second time substantially coincides with the fourth time.

17. A method according to claim 15, wherein the first and second times are interlaced with the third and fourth times.

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

(i) determining that information related to the primary image is not sufficiently reliable to determine the position of the tracking device, and

(ii) evaluating information related to the secondary image to determine the movement of the tracking device absent further evaluation of the information related to the primary image.

19. A method according to claim 14, further comprising repeatedly capturing frames of the primary image at a first rate, and repeatedly capturing frames of the secondary image at a second rate.

20. A method according to claim 19, wherein the first and second rates are substantially the same.