Patent ID: 7289107

Claim:
A method for performing auto calibration in a relative pointing device for a computer user interface having, a stick control for operation by the user; a sensor surface having X and Y electrical signal values at various contact positions on said sensor surface; a contact surface on which the sensor surface may or may not be in contact; a contact actuated by the user through the stick control for movement between contact positions along the sensor surface; the stick control having a central pointing position at which the user expects there to be no cursor movement, and having at this central pointing position X and Y electrical signal values, the stick control having positions displaced from the central pointing position to cause the cursor to move in a direction corresponding to the direction of the displacement, and at a speed corresponding to the magnitude of the displacement; the sensor surface and contact outputting a pair of X and Y electrical signal values with respect to the position of the contact on the sensor plane, the process of auto calibration of the relative pointing device comprising the steps of: making contact between the contact surface and the sensor surface; determining Xcenter and Ycenter values by recording the X and Y electrical signal values at the point in time when the contact is first established; determining the current X and Y electrical signal values with respect to the position of the contact on the sensor plane at a subsequent time; and, calibrating the relative pointing device at the subsequent time by subtracting the recorded Xcenter and Ycenter values from the current X and Y electrical signal values.