| 摘要 |
PROBLEM TO BE SOLVED: To simplify the circuitry by controlling the time interval for connecting a discharge circuit with an electromechanical energy conversion element equal to the resonant oscillation period and regulating the time interval for connecting the discharge circuit with the electromechanical energy conversion element. SOLUTION: An oscillation period detector 7 detects the period of resonant oscillation of a circuit comprising an oscillator 100-4 and an inductive element 23. A pulse width comparator 8 has input connected with the outputs from an oscillation period detector 7 and an oscillator drive logic 4 and output connected with a microcomputer MC 1. When the output level of pulse width comparator 8 is L, the MC 1 commands the oscillator drive logic 4 to prolong the time interval Tc by a predetermined amount from current time interval using a modulation signal of interval Tc. Since a drive signal Sb has a period Ta at that moment, an interval Tr=Ta-Tc is shortened as the interval Tc is prolonged and the interval Tr approaches an oscillation period Tk. |
