Determination of pen location on display apparatus using piezoelectric point elements

A stylus location system comprises a field emission device having an anode plate 32 and an emitter plate 2, and a plurality of piezoelectric point elements 34, 42 coupled to the anode plate. The piezoelectric point elements 34, 42 are capable of transforming electrical energy into ultrasonic energy and transforming ultrasonic energy into electrical energy. A stylus 30 is also coupled to the anode plate 32 and circuitry 36, 46, 48 is coupled to the piezoelectric point elements 42 for determining the position of the stylus 30. The circuitry 36 may also send a video data signal to the emitter plate 2 in response to the position determination.