Device for driving a piezoelectric element
AssigneeToyota Jidosha Kabushiki Kaisha
InventorMasaki Mitsuyasu
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Abstract
A device for driving a piezoelectric element comprising a power condenser for charging the piezoelectric element. When the discharging operation of the piezoelectric element is started, the piezoelectric element is initially discharged to the high voltage side terminal of the power condenser via a discharging coil and then discharged to the ground via the discharging coil. When the discharging operation is carried out, the voltage at the terminal of the piezoelectric element drops to a minimum voltage. The start time of the discharge to the ground is controlled so that the minimum voltage becomes equal to a predetermined negative voltage.
Claims17
A device for driving a piezoelectric element, comprising:
- a power condenser having a high voltage side terminal;
- first switching mans connected between the piezoelectric element and the high voltage side terminal of said power condenser for charging the piezoelectric element by using a high potential at the high voltage side terminal of said power condenser;
- second switching means connected between the piezoelectric element and the ground for discharging the piezoelectric element to the ground via a first discharging coil;
- third switching means connected between the piezoelectric element and the high voltage side terminal of said power condenser for discharging the piezoelectric element to the high voltage side terminal of said power condenser via a second discharging coil;
- control means coupled to the second and third switching means for controlling said second switching means and said third switching means to initially discharge the piezoelectric element to the high voltage side terminal of said power condenser and then discharge the piezoelectric element to the ground;
- and
- detecting means coupled to the control means and coupled to the piezoelectric element for detecting a negative voltage at a terminal of the piezoelectric element after the discharging operation of the piezoelectric element is completed and before the charging operation of the piezoelectric element is started, said control means controlling a switching time of said second switching means to make said negative voltage equal to a predetermined voltage.
Dependencies are inferred from the claim text.