Actuator, shutter device, fluid control device, switch, and two-dimensional scanning sensor device

Patent metadata

Field	Value
Publication number	US-10340818-B2
Application number	US-201414910622-A
Country	US
Kind code	B2
Filing date	Jul 30, 2014
Priority date	Aug 8, 2013
Publication date	Jul 2, 2019
Grant date	Jul 2, 2019

Abstract

An actuator includes: an electrostatic actuation mechanism including a stationary electrode and a movable electrode; a first movable part driven by the electrostatic actuation mechanism; a first elastic support part that elastically supports the first movable part; an electret formed in at least one of the stationary electrode and the movable electrode; and a drive control unit that controls application of voltage to the electrostatic actuation mechanism. In the actuator a plurality of stable states are set in which the first movable part is positioned at a stable position at which an electrostatic force generated by the electret matches with an elastic force exerted by the first elastic support part or at a stable position near such stable position. By applying a voltage to the electrostatic actuation mechanism, the first movable part may be displaced from any stable position to another stable position.

First claim

The invention claimed is:

1. An actuator comprising:
an electrostatic actuation mechanism including a stationary electrode and a movable electrode, the stationary electrode and the movable electrode being disposed in a planar arrangement;
a first movable part provided with the movable electrode and driven by the electrostatic actuation mechanism;
a first elastic support part that elastically supports the first movable part to enable the movable electrode to be displaced by sliding in a same plane with respect to the stationary electrode;
an electret formed in at least one of the stationary electrode and the movable electrode of the electrostatic actuation mechanism; and
a drive control unit that controls application of voltage to the electrostatic actuation mechanism, wherein:
a lower end of the movable electrode and a lower end of the stationary electrode in a direction perpendicular to a displacement direction of the movable electrode are positioned on a same single plane that is parallel to the displacement direction of the movable electrode;
in the actuator a plurality of stable states are set in which the first movable part is positioned at a stable position at which an electrostatic force generated by the electret matches with an elastic force exerted by the first elastic support part or at a stable position near such stable position; and
the drive control unit controls the electrostatic force generated by the electrostatic actuation mechanism to be weakened temporarily by applying a voltage to the electrostatic actuation mechanism to change any one of the stable states to another of the stable states to displace the first movable part from any stable position to another stable position.

2. The actuator according to claim 1 , wherein:
the electrostatic actuation mechanism includes at least a comb-teeth actuation unit that is provided with a stationary comb-teeth electrode as the stationary electrode and a movable comb-teeth electrode as the movable electrode, with a direction in which an insertion amount of the movable comb-teeth electrode changes with respect to the stationary comb-teeth electrode corresponding to a direction in which displacement by sliding occurs; and
the electret is formed in at least one of the stationary comb-teeth electrode and the movable comb-teeth electrode.

3. The actuator according to claim 2 , wherein:
the electrostatic actuation mechanism includes:
a first comb-teeth actuation unit having a first stationary comb-teeth electrode, and a first movable comb-teeth electrode that disengageably interdigitates with the first stationary comb-teeth electrode; and
a second comb-teeth actuation unit having a second stationary comb-teeth electrode, placed opposite to and at a distance from the first stationary comb-teeth electrode, and a second movable comb-teeth electrode that disengageably interdigitates with the second stationary comb-teeth electrode;

the first movable part is arranged between the first stationary comb-teeth electrode and the second stationary comb-teeth electrode and is provided with the first movable comb-teeth electrode and the second movable comb-teeth electrode;
the first elastic support part elastically supports the first movable part to enable the first movable part to be displaced by sliding in a direction in which respective insertion amounts of the first and second movable comb-teeth electrode to the first and second stationary comb-teeth electrodes change;
the electret has a first electret provided in at least one of the first stationary comb-teeth electrode and the first movable comb-teeth electrode and a second electret provided in at least one of the second stationary comb-teeth electrode and the second movable comb-teeth electrode;
the plurality of stable positions being set include:
a first stable position, which is a stable position, at which the first movable comb-teeth electrode is drawn by the first stationary comb-teeth electrode to a position at which an insertion amount of the second movable comb-teeth electrode becomes zero and a first electrostatic force generated by the first electret matches with an elastic force exerted by the first elastic support part, or a stable position set near such stable position; and
a second stable position, which is a stable position, at which the second movable comb-teeth electrode is drawn by the second stationary comb-teeth electrode to a position at which an insertion amount of the first movable comb-teeth electrode becomes zero and a second electrostatic force generated by the second electret matches with an elastic force exerted by the first elastic support part, or a stable position set near such stable position;

the drive control unit applies a first voltage to weaken the first electrostatic force to the first comb-teeth actuation unit to displace the first movable part from the first stable position to the second stable position; and
the drive control unit applies a second voltage to weaken the second electrostatic force to the second comb-teeth actuation unit to displace the first movable part from the second stable position to the first stable position.

4. The actuator according to claim 3 , wherein:
the first stationary comb-teeth electrode or the first movable comb-teeth electrode has a comb-teeth shape such that magnitude of the first electrostatic force changes in a plurality of steps according to an insertion amount of the first movable comb-teeth electrode to enable a plurality of first intermediate stable positions to be set, at which the first and second electrostatic forces match with an elastic force exerted by the first elastic support part, between the first stable position and the second stable position; and
the drive control unit controls an applied voltage to at least one of the first comb-teeth actuation unit and the second comb-teeth actuation unit to displace the first movable part to any one of the first stable position, the second stable position, and the plurality of first intermediate stable positions.

5. The actuator according to claim 3 , further comprising:
a third stationary comb-teeth electrode and a fourth stationary comb-teeth electrode, each being provided at a base and arranged opposite to and spaced apart from each other in a direction that crosses a direction of displacement of the first movable part;
a second movable part arranged between the third stationary comb-teeth electrode and the fourth stationary comb-teeth electrode and provided with a third movable comb-teeth electrode that disengageably interdigitates with the third stationary comb-teeth electrode and with a fourth movable comb-teeth electrode that disengageably interdigitates with the fourth stationary comb-teeth electrode; and
a second elastic support part that elastically supports the second movable part to enable the second movable part to be displaced by sliding with respect to the first movable part in the crossing direction, wherein:
the electret further includes a third electret provided in at least one of the third stationary comb-teeth electrode and the third movable comb-teeth electrode and a fourth electret provided in at least one of the fourth stationary comb-teeth electrode and the fourth movable comb-teeth electrode;
the plurality of stable positions being set further includes:
a third stable position, which is a stable position, at which the third movable comb-teeth electrode is drawn by the third stationary comb-teeth electrode to a position at which an insertion amount of the fourth movable comb-teeth electrode with respect to the fourth stationary comb-teeth electrode becomes zero and a third electrostatic force generated by the third electret matches with an elastic force exerted by the second elastic support part, or a stable position set near such stable position;

Assignees

• Univ Shizuoka Nat Univ Corp
• Omron Tateisi Electronics Co
• Kk saginomiya seisakusho

Inventors

• Suzuki Masato
• Mori Akito
• Hashiguchi Gen
• Sugiyama Tatsuhiko
• Imamoto Hiroshi
• Oba Masatoshi
• Mitsuya Hiroyuki
• Ashizawa Hisayuki
• Ishibashi Kazunori

Classifications

• B81B2203/051

  Translation according to an axis parallel to the substrate · CPC title

• B81B2203/0163

  Spring holders · CPC title

• B81B2203/0109

  Bridges · CPC title

• B81B2201/033

  Comb drives · CPC title

• B81B3/0054

  For holding or placing an element in a given position · CPC title