Patent ID: 8771192

Claim:
An ultrasonic sensor comprising: a substrate, a transmitter element formed above the substrate, the transmitter element including a transmission film adapted to transmit ultrasound through oscillation, a transmission piezoelectric body for causing the transmission film to oscillate, and a pair of actuation electrodes for applying an actuation voltage to the transmission piezoelectric body; a receiver element formed above the substrate, the receiver element being different from the transmitter element, the receiver element including a reception film adapted to oscillate through reception of the ultrasound, a reception piezoelectric body for converting oscillation of the reception film to an electrical signal, and a pair of receiver electrodes for picking up the electrical signal that is output from the reception piezoelectric body; a potential controller configured to bring the receiver electrodes to a first potential; a connection switching unit configured to switch a connection state of the receiver electrodes and the potential controller; a trigger signal generator configured to keep outputting a trigger signal during a trigger output period that is set to be longer than a transmission period in which the ultrasound is transmitted by the transmitter element, and an actuation controller configured to output an actuation signal applied to the actuation electrodes of the transmitter element while simultaneously activating the trigger signal generator, during the transmission period, the connection switching unit being configured to switch to a first state in which the potential controller and the receiver electrodes are connected, the connection switching unit being configured to switch to the first state in response to commencing output of the trigger signal from the trigger signal generator, and during a reception period in which the ultrasound is received by the reception element, the connection switching unit being configured to switch to a second state in which the potential controller and the receiver electrodes are disconnected, the connection switching unit being configured to switch to the second state in response to termination of the output of the trigger signal.