Importance

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Abstract

An apparatus that drives a piezoelectric actuator in response to charging and discharging command signals is disclosed. The apparatus includes an energy source that supplies electrical energy to the piezoelectric actuator. A charging circuit includes: a charging transistor connected to the energy source to control the amount energy supplied to the piezoelectric actuator, a charging inductor connected to the charging transistor to limit the rate of change of energy supplied to the piezoelectric actuator, and a charging thyristor disposed between the charging circuit and the piezoelectric actuator. A selecting circuit receives the charging command signal and responsively biases the charging thyristor ON to connect the piezoelectric actuator to the charging circuit. A comparator determines the magnitude of voltage applied to the piezoelectric actuator. A control circuit receives the charging command signal, and responsively biases the charging transistor alternately ON and OFF to control the amount of energy supplied to the piezoelectric actuator in response to the piezoelectric actuator voltage being less than an upper desired voltage value. Finally, the selecting circuit biases the charging thyristor OFF to disconnect the piezoelectric actuator from the charging circuit in response to the piezoelectric actuator voltage being greater than or equal to the upper desired voltage value.

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First Claim