Patent ID: 8047995
Filing Date: 2011-11-01
Classification: A61B,B06B,H04R,Y10T

Abstract:
1. An ultrasonic transducer comprising: a transducer cell including: a first electrode; a vibration membrane disposed on the first electrode, separated by an air gap portion; and a second electrode supported by the vibration membrane; a first conductive layer electrically connected to the first electrode; a second conductive layer disposed facing the first conductive layer and electrically connected to the second electrode; an electret for retaining a charge and applying a predetermined potential difference between the first electrode and the second electrode, the electret being disposed in a region between the first conductive layer and the second conductive layer, where the electret do not overlap with the transducer cell when viewed from a transmitting direction of ultrasonic waves generated by vibration of the vibration membrane.