| 摘要 |
PROBLEM TO BE SOLVED: To easily change the number of switching steps for sound pressure, to allow high speed switching, and to eliminate distortion of a generated sound. SOLUTION: Output sound pressure of a sounding body 202 is changed by a level of a direct current voltage when driven by a voltage superposed with an alternating current voltage to the direct current voltage. The direct current voltage from a voltage generating circuit 10 is added to an output signal of an oscillation circuit 4 by an adder circuit 12 to be supplied to the sounding body 202. The circuit 10 is constituted of a D/A converter, and an output direct current voltage is changed when a value of a control signal 8, that is a digital signal, is changed. Therefore, the sound pressure is easily changed by switching of the control signal 8, and switching steps are set variously in the number. Feedback resistance of an operation amplifier is switched by an analog switch in another sounding body driver to prevent distortion from being generated. The analog switch is combined with a transistor circuit to allow high speed switching.
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