| 摘要 |
PROBLEM TO BE SOLVED: To provide a piezoelectric pedometer wherein battery life is made long and stable operation voltage is kept. SOLUTION: An inverter logic element 7-4 is provided. It sets roughly three- fourths of operation voltage Vs to a threshold voltage Vth and compares it with an input voltage Vin, and then it detects Vin>=Vth and sets an output voltage Vout as a ground potential. For example, a power supply voltage Vcc is outputted from the output port O1 of a microcomputer 7-3 at a measuring level 1. In this case, charging current Is flows in the emitter-base of a transistor, a red light emitting diode D1, and a resistance R8 in order, and charges are accumulated in a capacitor C1. A charging voltage Vc1 at the time when the capacitor is fully charged is set to an operation voltage Vs. When the input voltage Vin exceeds the threshold voltage Vth, the output of the logic element 7-4 is at the ground level, and the accumulated charges in the capacitor C1 are discharged. Contrarily, when the input voltage Vin drops below the threshold voltage Vth, the capacitor C1 is charged promptly. Thus, only when a pulse voltage is produced in a piezoelectric element 3, current flows in a resistance R9, and standby current ideally becomes zero.
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