Cursor control device

1. In a computer system having a processor operatively coupled to a cursor control device and a cursor, the cursor control device further including a light source and a sensor, a method of moving the cursor comprising the steps of:

programming the processor with a set of instructions;

using the processor and the instructions to perform the steps of:

determining a measured tracking value representative of motion of the cursor control device sensed by the sensor;

performing a projection calculation for determining a projected tracking value, the projection calculation involving a historical tracking value;

calculating a tracking confidence value based on an illumination value representative of an intensity of light sensed by the sensor;

generating an enhanced tracking value representative of a sum of the tracking confidence value multiplied by the measured tracking value and a value of (1−the tracking confidence value) multiplied by the projected tracking value; and,

moving the cursor according to the enhanced tracking value.

2. A method according to claim 1 , wherein the sensor provides a pair of measured tracking values representative of motion of the cursor control device,

wherein the step of performing a projection calculation includes determining a pair of projected tracking values using a pair of historical tracking values,

wherein the step of generating an enhanced tracking value includes determining a pair of enhanced tracking values; and,

wherein the step of moving the cursor includes moving the cursor according to the pair of enhanced tracking values.

3. A method according to claim 2 , wherein each of the pair of measured tracking values, projected tracking values, historical tracking values, and enhanced tracking values is representative of motion in a respective one of a pair of orthogonal directions.

4. A method according to claim 1 , wherein the step of calculating a tracking confidence value further comprises the step of performing an illumination calculation for determining the illumination value, the illumination calculation involving a shutter value received from the sensor for a subject sensor scan and a brightness value indicative of an amount of light emitted from the light source during the subject sensor scan.

5. A method according to claim 4 , wherein the illumination value is representative of an intensity of light sensed by the sensor during the subject sensor scan.

6. A method according to claim 5 , further comprising the step of controlling the intensity of light emitted by the light source.

7. A method according to claim 6 , wherein the step of controlling the intensity of light emitted by the light source includes controlling the intensity of light based on a shutter value signal received from the sensor.

8. A method according to claim 6 , wherein the step of controlling the intensity of light emitted by the light source includes controlling the intensity of light based on a contrast signal received from the sensor.

9. A method according to claim 6 , wherein the illumination value is based on information received from the sensor and an intensity at which the light source is controlled during the step of controlling the intensity of light.

10. A method according to claim 1 , wherein the enhanced tracking value is such that if the tracking confidence value is a first value then the enhanced tracking value is equal to the measured tracking value, and if the tracking confidence value is a second value then the enhanced tracking value is equal to the projected tracking value.

11. A method according to claim 10 , wherein the enhanced tracking value is such that if the tracking confidence value is a third value then the enhanced tracking value is equal to a weighted combination of each of the measured tracking value and the projected tracking value.

12. A method according to claim 1 , wherein the measured tracking value is representative of motion sensed by the sensor during a subject sensor scan, and the historical tracking value is related to at least one sensor scan prior to the subject sensor scan.

13. A method according to claim 12 , wherein the historical tracking value is calculated using the enhanced tracking value for said at least one sensor scan prior to the subject sensor scan.

14. A method according to claim 1 , wherein the step of generating an enhanced tracking value includes the further step of applying the formula:

dx =( Mdx )*alpha+(1.0−alpha)* Pdx

wherein:

dx is the enhanced tracking value;

mdx is the measured tracking value;

alpha is the tracking confidence value; and,

Pdx is the projected tracking value.

15. A method according to claim 1 , further comprising the step of storing the enhanced tracking value.

16. A method according to claim 15 , wherein the steps of performing a projection calculation, calculating a tracking confidence value and generating an enhanced tracking value are repeated using the stored enhanced tracking value as a basis for determining the historical tracking value.