DRIVE CONTROL METHOD OF ELECTROSTATIC-TYPE ULTRASONIC TRANSDUCER, ELECTROSTATIC-TYPE ULTRASONIC TRANSDUCER, ULTRASONIC SPEAKER USING ELECTROSTATIC-TYPE ULTRASONIC TRANSDUCER, AUDIO SIGNAL REPRODUCING METHOD, SUPERDIRECTIONAL ACOUSTIC SYSTEM, AND DISPLAY

摘要

PROBLEM TO BE SOLVED: To provide a push-pull-type electrostatic-type ultrasonic transducer that improves the conversion efficiency of electric-acoustic energy.;SOLUTION: The transducer includes a first electrode 10A having through holes 14, a second electrode 10B having through holes each of which is paired with the corresponding through hole of the first electrode, and an oscillation film 12 sandwiched between a pair of the first and the second electrodes and having a conductive layer 121 to which direct current bias voltage is applied. When a pair of electrodes and the oscillation film are provided and a wavelength obtained from a resonance frequency at a mechanical oscillation resonance point of the oscillation film is lambda, a thickness t of a pair of respective fixed electrodes is (lambda/4)*n or substantially (lambda/4)*n (where lambda: wavelength of ultrasonic wave, n: positive odd number). AC signals as modulation waves produced by modulating carrier waves in an ultrasonic frequency band by signal waves in an audio frequency band are applied between a pair of the electrodes.;COPYRIGHT: (C)2007,JPO&INPIT