Driving device for capacitance type actuator and driving device for ink jet head
View Patent ↗An actuator is sequentially charged with output voltage “E/2” of a voltage source and output voltage “E” of a voltage source. After the charging, “Q/2” of electric charge “Q” stored in the actuator is discharged on a path returning to the voltage source. Subsequent to the discharging, the remaining all electric charge “Q/2” stored in the actuator is discharged on a closed circuit.
1. A driving device for a capacitance type actuator that functions according to a series of charging and discharging sequence, the driving device comprising:
a driving power supply which outputs charging voltage given to the actuator;
at least one intermediate voltage source including a reference voltage source that outputs reference voltage, a voltage follower circuit that buffers output of the reference voltage source, a smoothing capacitor charged by the output of the voltage follower circuit, and a current limiting unit that limits a current of output of the voltage follower circuit that charges the smoothing capacitor, wherein the intermediate voltage source gives the voltage generated at the smoothing capacitor as intermediate potential at a stage halfway in charging or discharging by the charging and discharging sequence to the actuator;
a discharging path for discharging electric charge remaining in the actuator and consuming energy corresponding to the electric charge; and
a controller, in charging the actuator, which charges electric charge in the actuator from the intermediate voltage source and thereafter charging electric charge in the actuator from the driving power supply and, in discharging of the actuator, discharging electric charge from the actuator to the smoothing capacitor of the intermediate voltage source and thereafter discharging electric charge of the actuator with the discharging path.
2. The device according to claim 1 , wherein
the electric charge input to the intermediate voltage source from the actuator by the discharging sequence is equal to the electric charge output to the actuator from the intermediate voltage source by the charging of the charging sequence, and
the voltage follower circuit has functions of both a current source and a current sink.
3. The device according to claim 1 , wherein
the electric charge input to the intermediate voltage source from the actuator by the discharging sequence is larger than the electric charge output to the actuator from the intermediate voltage source by the charging sequence, and
the voltage follower circuit has a function of a current sink.
4. The device according to claim 1 , wherein
the electric charge output to the actuator by the intermediate voltage source by the charging sequence is larger than the electric charge input to the intermediate voltage source from the actuator by the discharging sequence, and
the voltage follower circuit has a function of a current source.