Optical navigation sensor with variable tracking resolution

• US 20080007526A1
• Filed: 07/10/2006
• Published: 01/10/2008
• Est. Priority Date: 07/10/2006
• Status: Active Grant

• Current Assignee: Cypress Semiconductor Corporation (Infineon Technologies AG)
• Original Assignee: Cypress Semiconductor Corporation (Infineon Technologies AG)
• Inventors: Xu, Yansun, Carlisle, Clinton B., Trisnadi, Jahja I., Todoroff, Brian
• Granted Patent: US 7,728,816 B2
• Time in Patent Office: Days
• US Class Current: 345/163
• 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

Abstract

One embodiment relates to a method of sensing motion of an optical sensor relative to a surface. A first resolution and a second resolution are set. Measurement signals are obtained from a sensor array, and the motion of the optical sensor relative to the surface is tracked using the measurement signals. The tracking of the motion in a first dimension is performed at the first resolution, and the tracking of the motion in a second dimension is performed at the second resolution. Another embodiment relates to an optical sensor apparatus for sensing motion relative to a surface, wherein the tracking of the motion is performed at a variable resolution along each of two axes. Other embodiments and features are also disclosed.

Claims

1. A method of sensing motion of an optical sensor relative to a surface, the method comprising:

setting a first resolution and a second resolution;

obtaining measurement signals from a sensor array; and

tracking the motion of the optical sensor relative to the surface using the measurement signals,

wherein the tracking of the motion in a first dimension is performed at the first resolution, and the tracking of the motion in a second dimension is performed at the second resolution.

2. The method of claim 1, wherein the measurement signals comprise analog differential signals obtained from a two-dimensional comb-array detector.

3. The method of claim 1, wherein the resolutions are set by a controller depending upon an estimated velocity of the optical sensor relative to the surface.

4. The method of claim 3, wherein a higher resolution for a dimension is set based on a slower estimated speed along that dimension.

5. The method of claim 1, wherein the first and second resolutions are independently controllable.

6. The method of claim 1, wherein the first and second dimensions correspond to orthogonal axes.

7. The method of claim 1, wherein the optical sensor comprises an optical mouse device.

8. The method of claim 1, wherein the tracking of the motion in the first dimension is performed using a first division operation, and wherein the tracking of the motion in the second dimension is performed using a second division operation.

9. The method of claim 8, wherein the first division operation comprises dividing a measured displacement along the first dimension by a first divisor to obtain a first output and a first remainder, and wherein the second division operation comprises dividing a measured displacement along the second dimension by a second divisor to obtain a second output and a second remainder.

10. The method of claim 9, wherein a first remainder from a previous frame is added to the measured displacement along the first dimension prior to said first division operation, and wherein a second remainder from a previous frame is added to the measured displacement along the second dimension prior to said second division operation.

11. The method of claim 10, wherein the first and second division operations are performed by data processing circuitry executing computer-readable code from a memory.

12. The method of claim 10, wherein the first and second division operations are performed by dedicated circuitry.

13. A method of sensing motion of an optical sensor relative to a surface, the method comprising:

obtaining analog differential signals from a sensor array;

converting the analog differential signals to digital signals; and

tracking the motion of the optical sensor relative to the surface using the digital signals,

wherein an upper limit of resolution of the motion tracking is controlled by varying a resolution of said analog-to-digital conversion.

14. The method of claim 13, wherein the sensor array comprises a two-dimensional comb array.

15. The method of claim 13, wherein the resolution of said analog-to-digital conversion is changed by varying an electrical current used to generate a slope signal for said analog-to-digital conversion.

16. An optical sensor apparatus for sensing motion relative to a surface, the apparatus comprising:

a sensor array generating analog differential signals;

analog-to-digital conversion circuitry for converting the analog differential signals to digital signals; and

data processing circuitry configured to track the motion of the apparatus relative to the surface using the digital signals,

wherein the tracking of the motion is performed at a variable resolution along each of two axes.

17. The apparatus of claim 16, wherein the sensor array comprises a two-dimensional comb array.

18. The apparatus of claim 16, wherein the variable resolution along one axis is independent of the variable resolution along another axis.

19. The apparatus of claim 16, wherein said variable resolution is implemented by using a division operation.

20. The apparatus of claim 16, wherein an upper limit of said variable resolution is controlled by varying a resolution of the analog-to-digital conversion circuitry.