JP3052469B2 - Electrostatic actuator - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ultra-small electrostatic actuator having an outer dimension of less than a millimeter applied to the field of micro-mechatronics.

[0002]

2. Description of the Related Art Recently, as an actuator applied to the field of micro-mechatronics, an ultra-small electrostatic actuator manufactured by using a micro-machining technology of IC manufacturing has been proposed and its development has been advanced. This electrostatic actuator operates by using an electrostatic force as a drive source instead of a conventional electromagnetic force.
Vol. 3, No. 3 (1990), “Micro Electrostatic Motor” (author: Hiroyuki Fujita) Item: 4.21 The elastically supported actuator (p. 198)
The linear vibration structure of a polycrystalline Si supported by a 00 μm beam) and FIG. 7 (polycrystalline torsional vibration structure).

In the above-mentioned vibration-type electrostatic actuator, a comb-shaped movable electrode is integrally formed on a vibrator (movable portion) supported by a spring, and the comb teeth are alternately opposed to the movable electrode. It has a pair of left and right comb-shaped fixed electrodes arranged so as to be assembled, and by alternately switching the applied voltage between the movable electrode and the pair of left and right fixed electrodes, an electrostatic attraction force acting between the fixed electrode and the movable electrode The vibrator is driven to vibrate in a linear direction or a rotational direction by utilizing the above.

[0004]

The above-mentioned vibration-type electrostatic actuator is designed to take out the output directly from the vibrator supported by the spring. Therefore, its movable range is the expansion and contraction range of the spring supporting the vibrator. , The range of application and intended use are naturally restricted, and the problem remains that the method cannot be applied to applications that require a large amount of displacement. The present invention has been made in view of the above points, and its object is to limit the range of expansion and contraction of a spring by combining new components based on the above-mentioned vibration type electrostatic actuator. It is another object of the present invention to provide a linear or rotary electrostatic actuator which can move a moving member stepwise in a fixed direction with a large displacement without applying frictional resistance, spring resistance, or the like.

[0005]

In order to solve the above-mentioned problems, an electrostatic actuator according to the present invention comprises a moving member, a stator opposed to the moving member with a gap on both sides of the moving member, and a carrier. And an electrostatic vibrating means for vibrating the carrier in parallel with the moving direction of the moving element, and an electrostatic attraction means for alternately attracting the moving element to the stator and the moving element. And the stator in synchronization with this vibration action,
The moving element is configured to be driven stepwise in a fixed direction in combination with the suction operation of alternately attracting the moving element.

Here, in the electrostatic actuator having the above-mentioned structure, the electrostatic vibrating means is connected to the carrier by a spring-supported movable support, and the movable support is moved in parallel with the driving direction of the mover by the support. A vibrator comprising a comb-shaped movable electrode projecting to both sides, a pair of comb-shaped fixed electrodes arranged alternately with the comb teeth arranged opposite to the movable electrode; A switching element configured to alternately apply a power supply voltage between the electrode and the pair of fixed electrodes, and further comprising a power supply, and a movable element and a stator connected to the power supply circuit. , And a switching element for alternately applying a power supply voltage between the mover and the carrier.

In the above construction, the movable member is a strip-shaped flat plate or a linear electrostatic actuator in which the movable member is linearly driven stepwise in a linear direction, or a disk supporting the movable member with a rotating shaft. As a result, the present invention can be embodied as a rotary electrostatic actuator driven stepwise in the rotation direction. Further, as for the linear electrostatic actuator, as a means for stably guiding the moving element in the stepping direction, the stator facing the moving element of the strip-shaped flat plate is electrically driven in a direction perpendicular to the stepping moving direction of the moving element. A voltage is applied between the central part and the moving element while maintaining the left and right ends at the same potential as the moving element. Or a stator facing the rod-shaped mover, and a groove for guiding the mover provided along the moving direction of the mover at the center of the suction surface of the carrier. There is a configuration.

[0008]

With the above arrangement, the actuator operates as follows. In other words, in the standby state, the movable element is held on the stator by electrostatic force generated by voltage application. here,
The carrier is vibrated back and forth in parallel with the moving direction of the mover via the vibrator, and when the carrier moves backward to the maximum amplitude position, the mover is released from the stator and settled on the mover. Electroadsorb. Subsequently, when the carrier moves forward to the maximum amplitude position on the opposite side while holding and holding the movable element, the movable element is released from the transport element at this point and electrostatically attracted to the stator. As a result, the moving element moves forward by one step without causing sliding friction with the stator or the conveying element. Hereinafter, by repeating the above operation in synchronization with the vibration of the conveying element, The oscillating motion is rectified, and the moving element continuously moves in a fixed direction. In addition, there is no limit on the displacement of the moving element, and no resistance such as sliding friction and spring resistance is received during the stepping movement.

A linear electrostatic actuator can be obtained by linearly moving the movable element as a strip-shaped flat plate or a rod in a linear direction. Further, the movable element is formed into a disk supported by a rotating shaft. By driving stepwise in the rotational direction, a rotary electrostatic actuator can be obtained.

On the other hand, in the case of the rotary electrostatic actuator, since the moving element is supported by the rotating shaft (supported by the bearing), there is no danger that the stepping operation will deviate from the rotating trajectory. Unless a special guide means is provided and restrained for the child, there is a possibility that the linear member may deviate from the straight path due to an external force applied to the movable member when alternately moving between the stator and the carrier. In this regard, as described in the above-mentioned solution, the stator facing the slider of the strip-shaped flat plate is fixed to the central portion and the left and right ends electrically insulated from each other in the direction perpendicular to the stepping movement direction of the slider. By applying a voltage between the central part and the movable element and adsorbing the movable element to the central part of the stator while maintaining the left and right ends at the same potential as the movable element, In the process of attracting the slider to the stator, electrostatic attraction is applied between the slider and the center of the stator, and electrostatic repulsion is applied between the left and right ends. The displacement of the child to the left and right is reliably prevented. Also, in a configuration in which a concave groove for guiding the moving element is provided along the moving direction of the moving element in the center of the suction surface of the moving element and the stator facing the rod-shaped moving element, the moving element can be moved in the same manner as described above. It can be prevented from being displaced in the direction and deviating from the track.

[0011]

Embodiments of the present invention will be described below with reference to the drawings. Embodiment 1 First, the configuration and operation principle of an embodiment of a linear electrostatic actuator are shown in FIGS. 1, 2 and 3. FIG. In the figure, first, the electrostatic actuator is
, A stator 2, a carrier 3, a vibrator 4 integrally coupled to the carrier, a power supply 5, and switching elements 6 and 7 connected to a power supply circuit. here,
The mover 1 is a strip-shaped flat plate made of a conductive material, and it is assumed that the mover 1 moves in the longitudinal direction along the arrow P direction. The stator 2 has an insulating film 21 on the surface facing the movable member 1.
(See FIG. 3). The conductor is a plate-shaped conductor, and is provided on the lower surface side of the movable element 1 so as to be opposed to each other with a minute gap of several tens μm or less. On the other hand, the carrier 3 is a flat conductor having an insulating film 31 (see FIG. 3) provided on a surface facing the movable element 1.
Are arranged facing each other with a minute gap therebetween.

As shown in FIG. 2, the vibrator 4 connected to the carrier 3 has a window frame-shaped outer frame 41 and a movable support 42 formed as a beam extending from both sides of the carrier 3.
A spring portion 43 formed in a meandering shape between the support body 42 and the outer frame 41; a comb-shaped movable electrode 44 projecting to both sides from the support body 41; A pair of comb-shaped fixed electrodes 45 and 46 are provided so as to protrude inside the outer frame 41 and are arranged so that the teeth are staggered, and the outer frame 41 supports the movable support 42.
a and a portion 41 for individually supporting the fixed electrodes 45 and 46
b and 41c, and the respective parts are electrically insulated from each other via an insulator 47. The outer frame portions 41a and 41b are connected to the power supply 5 via the switching element 6 of the electronic gate element, and the outer frame portion 41a is connected to the ground.

In such a configuration, if the switching element 6 is made conductive between the c-contact and the a-contact, a power supply voltage is applied between the movable electrode 44 and the fixed electrode 45, and conversely, the power is applied between the b-contact and the b-contact. When the conduction is established, a voltage is applied between the movable electrode 44 and the fixed electrode 46. When a voltage is applied, the movable electrode 44 is drawn into the fixed electrodes 45 to 46 by electrostatic force. Therefore, if the power supply voltage is alternately applied to the fixed electrodes 45 and 46 at a predetermined cycle, the carrier 3 vibrates in the arrow X direction.

On the other hand, the moving element 1 and the stator 2 are connected to a power source 5 via a switching element 7 as shown in FIG. Here, if the switching element 7 is made conductive between the c contact and the a contact, the voltage of the power supply 5 is applied between the mover 1 and the stator 2, and conversely, the conduction is made between the b contact. For example, the potential between the mover 1 and the stator 2 becomes the same potential, and the voltage of the power supply 5 is applied between the mover 1 and the carrier 3. Then, the mover 2 is attracted to the stator 1 or the carrier 3 by electrostatic force in response to the voltage application.

Next, the operation of the electrostatic actuator configured as described above will be described with reference to FIG. FIG. 1A shows a standby state, in which the movable element 1 and the transport element 3 are set to the same potential, and a voltage is applied between the movable element 1 and the stationary element 2 to attract and hold the movable element 1 to the stationary element 2. Let it be. Next, when the actuator is operated, the carrier 3 is vibrated in parallel with the operation direction P of the moving element 1 by the operation of the vibrator 4 (see FIG. 2).
As shown in the figure, when the carrier 3 moves to the maximum amplitude position on the right side of the drawing, the contact of the switching element 7 is switched. As a result, the stator 2 and the mover 1 have the same potential, and the mover 1
A voltage is applied between the armature and the carrier 3, and the movable element 1 is released from the stator 2 and is attracted to the carrier 3. Subsequently, as shown in FIG. 4C, the carrier 3 is turned to the left on the paper surface and moved in the direction of the arrow P while the movable element 1 is being sucked by the driving of the vibrator 4.
When the switching element 7 is switched again when the carrier 3 has reached the maximum amplitude position, the moving element 1 is separated from the carrier 3 and is attracted to the stator 1 as shown in FIG. As a result, the moving element 1 moves stepwise in the direction of the arrow P by one step.

Hereinafter, the above operation is repeated in synchronization with the vibration of the vibrator 4 coupled to the carrier 3, whereby the vibrator 4
The oscillating operation of the carrier by the drive of the rectifier is rectified, and the mover 1 moves stepwise in the direction of arrow P. In addition, since the moving member 1 moves while being attracted and held alternately between the stator 2 and the carrier 3 during the stepping operation, no sliding friction is generated. It is not directly affected by drag. When the movable element 1 is moved to the right side opposite to the arrow P, the movable element 1 is attracted to the transport element 3 when the transport element 3 moves to the left end of the sheet,
The moving element 1 may be adsorbed to the stator 2 at the time when the moving element 1 is sent to the right end.

Next, FIGS. 4 and 5 show an embodiment of a means for preventing the moving element 2 from moving right and left and out of the straight path during the stepping operation of the actuator. First, FIG.
In the configuration described above, the stator 2 is divided into three sections, that is, a central section 22 and left and right end sections 23 and 24 in a direction perpendicular to the stepping direction P of the movable section 1, and the insulation film 21 electrically connects the sections. Electrically insulated. When the movable element 1 is attracted to the stator 2, the voltage of the power supply 5 is applied between the central portion 22 and the movable element 1, and the left and right ends 23 and 24 are kept at the same potential as the movable element 1. As a result, an electrostatic attractive force acts between the movable member 1 and the central portion 22 of the stator 2, and an electrostatic repulsive force acts between the left and right end portions 23 and 24. As a result, The moving element 1 is attracted to and attracted to the central portion 22 of the stator 2, so that the moving element 1 is prevented from shifting to the left and right and falling off the track. In addition, since the guide function utilizes electrostatic force, no mechanical friction is applied.

In the embodiment shown in FIG. 5, the movable element 2 is a rod-shaped body having a circular cross section. Guide grooves 25 and 32 having a radius of curvature are formed along the moving direction of the moving element 1. With this configuration, when the rod-shaped movable element 1 is attracted to the stator 2 or the carrier 3, the movable element 1 is fitted into the concave grooves 25 and 32, so that the movable element 1 shifts left and right and falls off the track. Can be reliably prevented.

Embodiment 2 Next, an embodiment of a rotary electrostatic actuator is shown in FIGS. 6 (a) and 6 (b). In this example,
A vibrator 4 on which the mover 1, the stator 2, and the carrier 3 are loaded is formed in a disk shape, and the mover 1 is connected to a rotating shaft 8 penetrating the stator 2 so as to be mounted on a bearing 9. Supported. Further, the carrier 3 and the vibrator 4 are dispersedly arranged at a plurality of locations on the periphery of the movable element 2, for example, at four locations at 90 ° intervals, and operate so as to synchronize with the peripheral direction.

The operation principle of this configuration is the same as that of the first embodiment, and the movable element 1 is moved to the stator 2 and the transport element 3 in synchronization with the vibration operation of the transport element 1 by the vibrator 4 as in the operation described with reference to FIG. The disc-shaped carrier 1 moves stepwise in the direction of rotation about the rotation shaft 8, and its output is taken out from the rotation shaft 8.

[0021]

Since the electrostatic actuator of the present invention is configured as described above, it has the following effects. (1) In the moving process of the moving element, the moving element can be stepped in a predetermined direction without adding any resistance such as sliding friction and spring resistance, thereby eliminating a friction loss which is a problem particularly in a micro actuator. As a result, an electrostatic actuator having high output characteristics can be obtained.

(2) Since the transfer element can obtain a large displacement amount without being restricted by the displacement amount unlike the conventional vibration type electrostatic actuator, the application of the actuator can be expanded. (3) A stable holding force at the stop position can be secured by electrostatically adsorbing the movable member to the stator while the actuator is stopped. (4) Linear and rotary actuators can be configured with the same basic structure.

[Brief description of the drawings]

FIG. 1 is a configuration perspective view of a linear electrostatic actuator corresponding to a first embodiment of the present invention.

FIG. 2 is a plan view of a combination structure of a carrier and a vibrator in FIG. 1;

FIGS. 3A to 3D are operation principle diagrams of the electrostatic actuator according to FIG. 1, wherein FIGS.

FIG. 4 is a cross-sectional view of a main part structure of an application example provided with a displacement preventing means for a movable element.

FIG. 5 is a cross-sectional view of a main part structure of an application example provided with a deviation prevention unit different from that of FIG. 4;

6A and 6B are configuration diagrams of a rotary electrostatic actuator corresponding to a second embodiment of the present invention, in which FIG.
(B) is a sectional view of (a).

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 mover 2 stator 21 insulating film 22 central part 23 left end 24 right end 25 guide groove 3 carrier 31 insulating film 32 guide groove 4 vibrator 42 movable support 43 spring part 44 movable electrode 45 fixed electrode 5 Power supply 6 Switching element 7 Switching element 8 Rotary axis

Continuation of the front page (56) References JP-A-5-76186 (JP, A) JP-A-3-169277 (JP, A) JP-A-63-136982 (JP, A) JP-A-2-84084 (JP, A) JP-A-2-41668 (JP, A) JP-A-63-95870 (JP, A) JP-A-61-296781 (JP, A) JP-A-60-210178 (JP, A) (58) Field surveyed (Int.Cl. ⁷ , DB name) H02N 1/00

Claims (7)

(57) [Claims] 1. An electrostatic actuator for driving a moving element stepwise in a fixed direction using electrostatic force as a driving source, comprising: a moving element;
A stator and a carrier opposed to each other with a gap therebetween on both sides of the movable element, electrostatic vibrating means for vibrating the transport element in parallel with the driving direction of the movable element, and a stationary element and the transport element for the movable element And an electrostatic attraction means for alternately attracting the moving member, and moving the movable member in combination with the attracting operation of alternately attracting the moving member to the stator and the carrier in synchronization with the vibrating operation. An electrostatic actuator characterized by driving a child stepwise in a fixed direction. 2. An electrostatic actuator according to claim 1, wherein said electrostatic vibrating means comprises a movable support member which is spring-supported by being connected to a carrier, and said movable member is provided in parallel with a driving direction of said movable member. A vibrator comprising a comb-shaped movable electrode projecting to both sides, a pair of comb-shaped fixed electrodes arranged alternately with the comb teeth arranged opposite to the movable electrode; An electrostatic actuator comprising a combination of a switching element for alternately applying a power supply voltage between an electrode and a pair of fixed electrodes. 3. The electrostatic actuator according to claim 1, wherein the electrostatic attraction means includes a power supply, and a power supply voltage connected between the power supply circuit and the mover and the stator, and between the mover and the carrier. An electrostatic actuator comprising: a switching element to be applied alternately. 4. A linear electrostatic actuator according to claim 1, wherein said moving element is driven stepwise in a linear direction as a strip-shaped flat plate or rod. 5. A rotary electrostatic actuator according to claim 4, wherein the movable element is formed into a disk supported by a rotating shaft and is driven stepwise in a rotating direction. 6. The electrostatic actuator according to claim 4, wherein the stator opposed to the strip-shaped flat-plate movable member is electrically insulated from each other in a direction perpendicular to the stepping movement direction of the movable member, and to the left and right. A voltage is applied between the central part and the movable element while the left and right ends are maintained at the same potential as the movable element, and the movable element is attracted to the central part of the stator by electrostatic force, while being divided into the both ends. An electrostatic actuator characterized in that: 7. The electrostatic actuator according to claim 4, wherein a groove for guiding the moving element is formed along the moving direction of the moving element at the center of the attracting surface of the stator and the moving element, which face the rod-shaped moving element. An electrostatic actuator characterized by being provided.