Apparatus and method for driving capacitance-type actuator
According to one embodiment, a apparatus for driving a capacitance-type actuator includes a first voltage source, a second voltage source, and a driver. The first voltage source outputs a first voltage to charge the capacitance-type actuator. The second voltage source outputs a second voltage to charge the actuator. The driver switches between first and second charges and first and second discharges. The first charge supplies the first voltage to the actuator. The second charge supplies the sum of the first voltage and the second voltage to the actuator. The first discharge emits a charge accumulated in the actuator and guides the charge to the second voltage source. The second discharge emits the charge accumulated in the actuator without guiding the charge to the second voltage source.
1. An apparatus for driving a capacitance-type actuator comprising:
a first voltage source that outputs a first voltage to charge the actuator;
a second voltage source that outputs a second voltage to charge the actuator;
a plurality of switches; and
a switch controller that controls the plurality of switches to charge and discharge the actuator in one of a first charge mode, a second charge mode, a first discharge mode, and a second discharge mode, wherein:
in the first charge mode, the switch controller controls the plurality of switches to form a charge path connecting the first voltage output from the first voltage source to the actuator,
in the second charge mode, the switch controller controls the plurality of switches to form a charge path connecting the first voltage output from the first voltage source and the second voltage output from the second voltage source in series, and connecting the series-connected first and second voltage outputs having a total voltage of the first voltage plus the second voltage to the actuator,
in the first discharge mode, the switch controller controls the plurality of switches to form a discharge path connecting the actuator to the second voltage source, and
in the second discharge mode, the switch controller controls the plurality of switches to form a discharge path from the actuator, the second discharge path excluding the second voltage source.
2. The apparatus of claim 1 , wherein
a charge output from the second voltage source in the second charge mode is equal to a charge guided to the second voltage source in the first discharge mode.
3. The apparatus of claim 2 , wherein
the second voltage source is a capacitor, and a capacitance of the capacitor is sufficiently larger than a capacitance of the actuator.
4. The apparatus of claim 3 , further comprising
a charge pump circuit that parallel-connects the first voltage source and the capacitor to charge the capacitor and series-connects the first voltage source and the capacitor to output a voltage that is double a voltage output from the first voltage source.
5. The apparatus of claim 3 , further comprising a voltage adjusting circuit that adjusts a charge voltage of the capacitor.
6. The apparatus of claim 5 , wherein
the voltage adjusting circuit is a linear regulator that generates a voltage to charge the capacitor from a voltage at a power supply line connected to a negative electrode of a DC power supply.
7. The apparatus of claim 5 , wherein
the voltage adjusting circuit is a tracking regulator that tracks of a reverse polarity of a potential at a power supply line connected to a positive electrode of the first voltage source.
8. The apparatus of claim 1 , wherein
the driver sets a potential at a negative electrode of the actuator to 0 V before the first charge mode is performed.
9. A method for driving a capacitance-type actuator comprising:
forming a first charge path connecting a first voltage output from a first voltage source to the actuator;
forming a second charge path connecting the first voltage output from the first voltage source and a second voltage output from a second voltage source in series, and connecting the series-connected first and second voltage outputs having a total voltage of the first voltage plus the second voltage to the actuator;
forming a first discharge path connecting the actuator to the second voltage output from the second voltage source; and
forming a second discharge path from the actuator, the second discharge path excluding the second voltage source.
10. The method of claim 9 , wherein
a charge output from the second voltage source when the second charge path is formed is equal to a charge input to the second voltage source when the first discharge path is formed.
11. The method of claim 9 , wherein
the second voltage source is a capacitor, and a capacitance of the capacitor is sufficiently larger than a capacitance of the actuator.
12. The method of claim 11 , wherein
the first voltage source is parallel-connected to the capacitor to charge the capacitor and series-connected to the capacitor to supply a voltage that is double an output voltage to the actuator.
13. The method of claim 11 , wherein
a charge voltage of the capacitor is adjusted by a voltage adjusting circuit.
14. The method of claim 13 , wherein
the voltage adjusting circuit is a linear regulator that generates a voltage to charge the capacitor from a voltage at a power supply line connected to a negative electrode of a DC power supply.
15. The method of claim 13 , wherein
the voltage adjusting circuit is a tracking regulator that tracks of a reverse polarity of a potential at a power supply line connected to a positive electrode of the first voltage source.
16. The method of claim 9 , wherein
the first charge path, the second charge path, the first discharge path and the second discharge path are formed sequentially in that order.
17. The method of claim 16 , wherein
a potential at a negative electrode of the actuator is set to 0 V before the first sequence mode is performed.
18. An apparatus for driving a capacitance-type actuator comprising:
a first voltage source that outputs a first voltage,
a second voltage source that outputs a second voltage,
a first switch positioned between a positive terminal of the first voltage source and a first terminal of an actuator circuit that includes the actuator;
a second switch positioned between a first terminal of the second voltage source and the first terminal of actuator circuit;
a third switch positioned between a second terminal of the second voltage source and a second terminal of the first voltage source, the second terminal of the second voltage source connecting to a second terminal of the actuator circuit; and
a fourth switch positioned between the first terminal of the second voltage source and the second terminal of the first voltage source, and
a driver that switches among a first charge mode, a second charge mode, a first discharge mode, and a second discharge mode by controlling each of the first, second, third and fourth switches to be on or off, wherein
in the first charge mode, a first voltage output from the first voltage source is supplied to the actuator circuit,
in the second charge mode, a voltage sum of the first voltage output from the first voltage source plus a second voltage output from the second voltage source is supplied to the actuator circuit,
in the first discharge mode, a charge accumulated in the actuator is discharged and supplied to the second voltage source, and
in the second discharge mode, a charge accumulated in the actuator is discharged without being supplied to the second voltage source.
19. The apparatus of claim 18 , wherein:
in the first charge mode, at least the first and third switches are controlled to be on and the fourth switch is controlled to be off.
20. The apparatus of claim 18 , wherein
in the second charge mode, the first and fourth switches are controlled to be on and the second and third switches are controlled to be off.