ULTRASONIC TRANSDUCER AND ULTRASONIC SPEAKER EMPLOYING IT

摘要

PROBLEM TO BE SOLVED: To provide an ultrasonic transducer capable of generating an acoustic signal having a sound pressure level high enough to attain parametric effect over a wide frequency band. SOLUTION: The ultrasonic transducer comprises a pair of fixed electrodes 10A and 10B including a conductive member; a vibrating membrane 12 with a conductive layer 121 sandwiched by the pair of fixed electrodes; and a member for holding the pair of fixed electrodes 10A and 10B and the vibrating membrane. The vibrating membrane 12 is formed of an insulator 120 and has an electrode layer 121 formed of a conductive material. The electrode layer 121 is applied with a unipolar DC bias voltage from a DC bias power supply 16 and an AC signal being output from a signal source 18 is superposed on the DC bias voltage. The pair of fixed electrodes have a plurality of the same number of holes 14 at positions facing each other through the vibrating membrane 12, and an AC signal is applied between the conductive members of the pair of fixed electrodes 10A and 10B from the signal source 18. COPYRIGHT: (C)2006,JPO&NCIPI