Patent ID: 8049720

Claim:
A mobile device comprising: a display; a fingerprint sensing circuit mounted within a depressible key; and a fingerprint movement detection circuit, operatively coupled to the fingerprint sensing circuit and to the display, and operative to determine a direction of movement independent of depression of the depressible key and a rate of movement, of skin texture being sensed by the fingerprint sensing circuit and to produce pointing output data for the display; wherein the fingerprint movement detection circuit determines at least one of a rate and a direction of movement of the skin texture by: modifying at least one of the previously stored images to produce a plurality of candidate displacement images each with an associated respective displacement movement vector; and compares by correlating the resolved first image against each of the plurality of candidate displacement images to produce a plurality of respectively associated displacement correlation scores; and wherein determining at least one of a rate and a direction of movement further includes: choosing the highest displacement correlation score and providing the associated respective displacement movement vector to determine the direction of movement of the skin texture.