Patent ID: 7907740

Claim:
An ultrasonic speaker, comprising: an electrostatic ultrasonic transducer, including a first electrode having a through hole, a second electrode having a through hole, a vibration film held between a pair of electrodes composed of the first electrode and the second electrode disposed so that the through hole of the first electrode and the through hole of the second electrode forms a pair, and having a conductive layer to which a direct-current bias voltage is applied, a modulated wave obtained by modulating a carrier wave in an ultrasonic frequency band with a signal wave in an audible frequency band being applied between the pair of electrodes, the through holes provided to the pair of electrodes acting as resonance tubes; a mechanical resonance frequency of the vibration film and an acoustic resonance frequency of the through holes being shifted from each other, a signal source for generating the signal wave in the audible frequency band; carrier wave supplying means that generates and outputs the carrier wave in the ultrasonic frequency band; and modulation means that modulates the carrier wave with the signal wave in the audible frequency band output from the signal source, wherein the electrostatic ultrasonic transducer is driven with a modulated signal output from the modulation means and applied between the pair of electrodes and an electrode layer of the vibration film.