| 摘要 |
PURPOSE:To obtain the level of high sound pressure under low power consumption by providing a controller controlling the carrier frequency of a carrier oscillator so as to minimize power inputted to an ultrasonic vibrator. CONSTITUTION:The output of a sound signal source 3 is inputted to a modulator 4. A sound signal is amplified and modulated with a carrier set to 40 kHz, and inputted to an ultrasonic wave source 2 through a power amplifier 6. Resistances R1, R2 and R3 asure a voltage and current inputted to the ultrasonic vibrator, and input an output to a multiplier 9 to attain power. A carrier frequency controller 10 compares the output of the multiplier 9 with a reference value stored in its memory, again stores the smaller value in the memory, and simultaneously transmits a positive or negative pulse to the carrier oscillator 5. lts oscillation frequency varies by + or -0.1 kHz, and the ultrasonic vibrator can be driven at an optimum frequency. |
