Patent ID: 7394454

Claim:
A handheld mouse device for tracking relative movement between said handheld mouse device and a tracking surface, comprising: an impedance sensor arranged with respect to a tracking surface, said impedance sensor having a measurement zone within which said impedance sensor measures an electrical capacitance; and a controller responsive to the measured capacitance of said impedance sensor for determining a distance of spatial separation between the handheld mouse device and the tracking surface relative to one another as a function of the measured capacitance, the handheld mouse being removable from the tracking surface, said controller initiating a non-tracking mode in which said controller suspends tracking of relative movement between said handheld mouse device and said tracking surface when said handheld mouse device is removed from the tracking surface and is spatially separated from said tracking surface by at least a lift-off detection distance, said controller further being responsive to the measured capacitance of said impedance sensor for determining a direction of relative movement between said handheld mouse device and said tracking surface as a function of the measured capacitance.