| 摘要 |
PROBLEM TO BE SOLVED: To provide an ultrasonic speaker system that transduces a waveform of a sound signal into aerial vibration with fidelity to obtain a high output and forms an excellent acoustic environment. SOLUTION: Each of first ultrasonic speakers each for outputting a carrier signal at an ultrasonic band and second ultrasonic speakers each for outputting a modulation signal resulting from frequency-modulating a carrier signal with a sound signal is provided with a drive section 17 for forming a magnetic field at a rear side of a metal-made diaphragm 15. In the drive section 17, a magnet 18 is joined with one-side end parts of pole pieces 19, an outer circumferential coil 20a and an inner circumferential coil 20b each for receiving a supplied signal are wound near the other end parts, and a gap 22 is formed between the other end faces 21 of the pole pieces 19 and the diaphragm 15. When the modulation signal and the carrier signal are respectively applied to the outer circumferential coil 20a and the inner circumferential coil 20b, the magnetic field formed around the other end faces 21 is changed to produce eddy currents on the surface of the diaphragm 15 and Lorentz's forces are produced to vibrate the diaphragm 15. COPYRIGHT: (C)2007,JPO&INPIT
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