US Patent 9195879 Air/object determination for biometric sensors

A fingerprint sensing apparatus may include a fingerprint sensor system and a control system capable of receiving fingerprint sensor data from the fingerprint sensor system. The control system may be capable of determining fingerprint sensor data blocks for at least a portion of the fingerprint sensor data and of calculating statistical variance values for fingerprint sensor data corresponding to each of the fingerprint sensor data blocks. The control system may be capable of determining, based at least in part the statistical variance values, whether an object is positioned proximate a portion of the fingerprint sensor system.