Drive device using polymer actuator
View Patent ↗An actuator includes an electrolytic layer, a first electrode layer, and a second electrode layer. The electrolytic layer includes a polymer and an ionic liquid included in the polymer. When a voltage that makes the first electrode layer a positive side is applied, the actuator deforms to be in a drive state, thereby driving a protruding member. In a period other than a drive period in which the protruding member is driven, a reverse voltage that makes the first electrode layer a negative side is applied, thereby rectifying the tendency of the actuator to bow or the like.
1. A drive device comprising:
a polymer actuator formed of a polymer containing an ionic liquid, the polymer actuator including a first electrode layer provided on a first surface thereof and a second electrode layer provided on a second surface thereof, the polymer actuator having a fixed end, and
a controller configured to control voltages applied across the first and second electrode layers,
wherein the polymer actuator drives a drivable member during a drive period when a drive voltage is applied in a first direction across the first and second electrode layers by bending in a direction in which the first surface becomes concave, while a reverse voltage is applied in a second direction opposite to the first direction across the first and second electrode layers in a period other than the drive period.
2. The drive device according to claim 1 , wherein the drivable member is a protruding member, and a free end of the polymer actuator causes the protruding member to protrude from a surface of a housing.
3. The drive device according to claim 1 , wherein, when power is turned ON, the polymer actuator bends in a direction in which the second surface becomes concave during a rectification period in which the reverse voltage is applied across the first and second electrode layers.
4. The drive device according to claim 3 , wherein the polymer actuator is being heated during the rectification period.
5. The drive device according to claim 1 , wherein, after an operation of the drivable member is completed, the polymer actuator bends in a direction in which the second surface becomes concave during a rectification period in which the reverse voltage is applied across the first and second electrode layers.
6. The drive device according to claim 5 , wherein the rectification period is set in accordance with a length of the drive period.
7. The drive device according to claim 6 , wherein the rectification period is set in accordance with an accumulated time of the drive period.
8. The drive device according to claim 1 , wherein the controller applies the reverse voltage having an absolute value greater than or equal to that of a rated voltage for a short time period in a period other than the drive period.
9. The drive device according to claim 1 , wherein the controller changes a time period in which the reverse voltage is applied in accordance with current feeding capability of a power supply provided in the drive device.
10. The drive device according to claim 1 , wherein the controller applies the reverse voltage when the drive device is being charged.
11. The drive device according to claim 1 , wherein the controller provides a rectification period in which the reverse voltage is applied such that the polymer actuator bends in a direction in which the second surface becomes concave.
12. The drive device according to claim 11 , wherein the controller continuously applies the reverse voltage with a certain magnitude during the rectification period.
13. The drive device according to claim 11 , wherein the controller intermittently applies the reverse voltage with a certain magnitude during the rectification period.
14. The drive device according to claim 11 , wherein the controller changes a magnitude of the reverse voltage during the rectification period.
15. The drive device according to claim 11 , wherein the controller temporarily applies a voltage in a same direction as that of the drive voltage in addition to applying the reverse voltage during the rectification period.
16. The drive device according to claim 11 , wherein the rectification period is provided at least one of: when power is turned ON; or when an operation of the drivable member is completed.
17. The drive device according to claim 11 , wherein the polymer actuator is being heated during the rectification period.
18. The drive device according to claim 11 , wherein the controller sets the rectification period in accordance with a length of the drive period.
19. The drive device according to claim 18 , wherein the controller sets the rectification period in accordance with an accumulated time of the drive period.