| 摘要 |
PROBLEM TO BE SOLVED: To raise sound pressure of a separate excitation type piezoelectric buzzer while keeping power supply voltage as it is. SOLUTION: In the separate excitation type piezoelectric buzzer which is driven by means of the application of voltage, there is provided a double voltage rectifier circuit 4 which boosts the power supply voltage to be double, and a negative voltage generating circuit 5 which generates negative power supply voltage. They are supplied to a buzzer drive circuit 2 driven by a pulse for ringing. The buzzer drive circuit 2 constituted by an inverter with a hysteresis characteristic amplifies amplitude of the pulse for ringing on the basis of voltage supplied from the double voltage rectifier circuit 4 and the negative voltage generating circuit 5, to supply it to the separate excitation type piezoelectric buzzer 3. COPYRIGHT: (C)2011,JPO&INPIT
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