Patent ID: 7223243

Claim:
An ultrasonic transmitter/receiver comprising: a piezoelectric polymer film adapted to transmit an ultrasonic acoustic signal from a front face along a signal path and to receive an ultrasonic acoustic signal at the front face along the signal path; a front electrode applied to the front face of the piezoelectric polymer film; a plurality of electrically independent and substantially rigid metallic backer electrodes adhered to a rear face of the piezoelectric polymer film; a plurality of amplifiers connected to each of the plurality of metallic backer electrodes to detect electrical signals there from; and a transmit circuit connected between the front electrode and at least one of the metallic backer electrodes to apply an electrical voltage therebetween to transmit an ultrasonic acoustic signal, wherein the amplifiers present a virtual ground point at their inputs and the transmit circuit applies a voltage to the front electrode with respect to this virtual ground.