PROTECTIVE CIRCUIT FOR PIEZOELECTRIC-ACTUATOR DRIVING POWER SUPPLY

摘要

PROBLEM TO BE SOLVED: To provide a protective circuit for a piezoelectric-actuator driving power supply capable of reducing the frequency dependence and rounding of voltage waveform amplitude while preventing the damage to a circuit element in a power device. SOLUTION: A current I flowing through a piezoelectric actuator element 3 is detected by a current detector 22, and input to a control circuit 24 through a first insulating coupling element 25. When the current I exceeds a set value ITH, a control signal S2 is transmitted to a switching element 21 through a second insulating coupling element 26 from the control circuit 24, and the switching element 21 is brought to the state of constant-current control in a short time of 10μsec or less, and the current I reaches the set value ITH or less.