JP2009300787A - Electrostatic actuator - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To obtain an electrostatic actuator that can be efficiently driven. <P>SOLUTION: An electrostatic optical scanner 100 (electrostatic actuator) is essentially composed of a disk-shaped first movable part 200, an annular second movable part 300 surrounding the first movable part 200, and an annular frame 400 surrounding the second movable part 300. First supporting parts 501, 502 are installed that connect the notches 311, 312 on the outer circumference 202 of the first movable part 200 and on the inner periphery of the second movable part 300, respectively. The first supporting parts 501, 502 have shapes in each of which a planar member of a rectangular parallelepiped is folded in multiple layers in the width direction, and have elasticity in the twisting direction while supporting the first movable part 200 in a rockable manner relative to the second movable part 300 with the first supporting parts 501, 502 as axes. An X-direction electrode 700 is composed of two near half circles 701, 702 which can be obtained by dividing the disk in two on the diameter. A Y-direction electrode 800 is composed of two near half rings which can be obtained by dividing the annular shape in two on the diameter with the X-direction electrode 700 housed in the inner periphery. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an electrostatic drive actuator used in an electrostatic drive optical scanner that changes the traveling direction of light using electrostatic force.

  A known electrostatic drive type optical scanner has a mirror surface formed on a movable part of an electrostatic drive type actuator and includes four electrodes provided to face the movable part.

  The movable portion is provided so as to be swingable around two swing shafts. In other words, the movable portion is attached to the inside of the gimbal ring via the first swing shaft, and the gimbal ring is placed inside the annular fixed portion via the second swing shaft connected to the outer peripheral surface thereof. It is attached. As a result, the movable part can rotate about the first swing axis with respect to the gimbal ring, and the gimbal ring can rotate about the second swing axis with respect to the fixed part.

  By appropriately applying voltages to the four electrodes, an electrostatic force is generated between the electrodes and the movable part, and the movable part is swung by the electrostatic force.

When viewed from the movable part, four electrodes are arranged in four quadrants formed by two swing axes. When the movable part is swung around one rocking shaft, a voltage is applied to two electrodes located on the same side of the rocking shaft. Similarly, when the movable portion is swung around the other swing shaft, a voltage is applied to two electrodes located on the same side of the swing shaft. When simultaneously driving the movable part around the two swing axes, two voltages for driving the movable part around the two swing axes are added and applied to one electrode.
JP 2005-208164 A

  When the gimbal ring and the electrode overlap each other when viewed from the mirror surface, an electrostatic force is generated between the gimbal ring and the electrode due to the voltage applied to the electrode to swing the movable portion around the first swing axis. Sometimes. Thereby, the operation of the gimbal ring may become unstable.

  In addition, when two voltages are added and applied to one electrode, the voltage applied to drive the movable portion around the first swing axis is applied to the movable portion around the second swing axis. May affect operation. Thereby, the operation of the movable part around the second swing axis may become unstable.

  Furthermore, since two voltages are added to one electrode and applied, there is a problem that the applied voltage becomes high.

  The present invention has been made in view of these problems, and an object thereof is to obtain an electrostatic drive actuator that can be driven efficiently.

  The electrostatic drive type actuator according to the present invention includes a first movable part, a second movable part provided around the first movable part, and the first movable part with respect to the second movable part. A first support portion that is swingably supported around the swing shaft, a frame portion provided around the second movable portion, and a second swing shaft that is not parallel to the first swing shaft. When viewed from a second support portion that supports the second movable portion with respect to the frame portion so as to be movable, and a straight line that is orthogonal to the first swing shaft and the second swing shaft, When viewed from the first electrode provided at a certain distance from the first movable part at a position overlapping with the first movable part, and a straight line perpendicular to the first support part and the second support part, A second electrode provided at a certain distance from the second movable portion at a position overlapping with the second movable portion, the first electrode comprising a first swing shaft and a second swing shaft; The first positive direction electrode and the first negative direction electrode are divided by the first swing shaft when viewed from a straight line orthogonal to the first swing shaft, and the second electrode has the first swing shaft. And a second positive electrode and a second negative electrode divided by the second swing shaft when viewed from a straight line orthogonal to the second swing shaft.

  The first electrode is preferably provided at a position that does not overlap the second movable part when viewed from a straight line orthogonal to the first and second oscillation axes. The voltage applied to the first electrode generates an electrostatic force between the first electrode and the second movable part, thereby preventing the operation of the second movable part from being affected.

  The second electrode is preferably provided at a position that does not overlap with the first movable part when viewed from a straight line orthogonal to the first swing axis and the second swing axis. The voltage applied to the second electrode prevents an electrostatic force from being generated between the second electrode and the first movable part and affecting the operation of the first movable part.

  It is desirable that the first electrode does not overlap the first support portion when viewed from a straight line orthogonal to the first swing axis and the second swing axis. The voltage applied to the first electrode generates an electrostatic force between the first electrode and the first support portion, and prevents the operation of the first support portion from being affected.

  It is desirable that the second electrode does not overlap the second support portion when viewed from a straight line orthogonal to the first swing axis and the second swing axis. The voltage applied to the second electrode prevents an electrostatic force from being generated between the second electrode and the second support part and affecting the operation of the second support part.

  The first support portion or the second support portion is preferably made of an elastic body.

  According to the present invention, an electrostatic drive actuator that can be driven efficiently can be obtained.

  Hereinafter, a first embodiment of an electrostatic drive actuator according to the present invention will be described with reference to the drawings. 1 to 4 show a configuration of an electrostatic drive type optical scanner 100 having an electrostatic drive type actuator.

  The electrostatic drive type optical scanner 100 (electrostatic drive type actuator) includes a movable part 110 and an electrode part 120. The movable part 110 is a disc-shaped first movable part 200 in which one of the circular surfaces is a mirror surface 201, an annular second movable part 300 surrounding the outer peripheral surface 202 of the first movable part 200, and It is mainly comprised from the cyclic | annular frame part 400 surrounding the outer peripheral surface 301 of the 2nd movable part 300. FIG. The first movable part 200, the second movable part 300, and the frame part 400 have substantially the same thickness. The centers of the first and second movable parts 200 and 300 and the frame part 400 are concentric.

  The second movable part 300 is provided with a total of four rectangular cutouts 311, 312, 321, 322, two on the inner peripheral surface 302 side and two on the outer peripheral surface 301 side. The two notches 311 and 312 on the inner peripheral surface 302 side are axisymmetric with respect to the central axis of the second movable portion 300, and the two notches 321 and 322 on the outer peripheral surface 301 side are the same.

  First support portions 501 and 502 that connect the outer peripheral surface 202 of the first movable portion 200 and the inner peripheral surface side cutouts 311 and 312 of the second movable portion 300 are provided. The first support portions 501 and 502 have a shape in which a rectangular parallelepiped plate-like member is folded several times in the width direction and forms a so-called thunder pattern. With this shape, the first support portions 501 and 502 have elasticity in the twisting direction. Thereby, the first movable part 200 is supported so as to be swingable with respect to the second movable part 300 about the first support parts 501 and 502.

  Second support portions 601 and 602 that connect the outer peripheral surface side cutouts 321 and 322 of the second movable portion 300 and the frame portion 400 are provided. The shape of the second support portions 601 and 602 is the same as the shape of the first support portions 501 and 502, and has elasticity in the twisting direction. Thereby, the second movable part 300 is supported so as to be swingable with respect to the frame part 400 with the second support parts 601 and 602 as axes. The frame part 400 is fixed to the electrode part 120.

  As shown in FIG. 1, the electrode unit 120 includes an X-direction electrode 700 for driving the first movable unit 200 around the X axis, and a Y-direction electrode for driving the second movable unit 300 around the Y axis. 800. The X-direction electrode 700 is composed of two substantially semicircles 701 and 702 obtained by dividing a disk by a diameter. In the figure, a substantially semicircle placed on the Y-axis negative side of the X axis in the figure is called an X positive electrode 701, and a substantially semicircle placed on the Y-axis positive side of the X axis is called an X negative electrode 702. The Y-direction electrode 800 is composed of two substantially half wheels obtained by dividing the ring shape by its diameter, and houses the X-direction electrode 700 on the inner periphery. In the figure, a substantially half wheel placed on the X axis positive side of the Y axis in the figure is called a Y positive electrode 801, and a substantially half wheel placed on the X axis negative side of the Y axis is called a Y negative electrode 802. In an idle state in which no potential difference is applied to the electrode unit 120, the Z axis orthogonal to the X axis and the Y axis coincides with the normal line of the mirror surface 201 of the first movable unit 200.

  The centers of the X direction electrode 700 and the Y direction electrode 800 are placed concentrically with the centers of the first and second movable parts 200 and 300 and the frame part 400 on the Z axis. The diameter of the X direction electrode 700 is substantially equal to the diameter of the first movable part 200, and the inner diameter and outer diameter of the Y direction electrode 800 are equal to the inner diameter and outer diameter of the second movable part 300. The first and second movable parts 200 and 300 and the X and Y direction electrodes 800 are, when viewed from their central axes (that is, the Z axis), the first movable part 200 and the X direction electrode 700, and the second The movable portion 300 and the Y-direction electrode 800 are provided so as to substantially overlap each other. In other words, when viewed from the Z-axis direction, the first movable part 200 and the Y-direction electrode 800 for driving around the X axis, and the second movable part 300 and the X-direction electrode for driving around the Y axis. 700 are arranged so as not to overlap each other.

  Further, when viewed from the central axis of the first and second movable parts 200 and 300, the X direction electrode 700 is divided into an X positive electrode 701 and an X negative electrode 702 by the swing axis of the first movable part 200, The Y-direction electrode 800 is divided into a Y positive electrode 801 and a Y negative electrode 802 by the swing axis of the second movable part 300.

  An X positive wiring 711 and an X negative wiring 712 for transferring charges to the X positive electrode 701 and the X negative electrode 702 are respectively provided on the substantially semicircular tops of the X positive electrode 701 and the X negative electrode 702.

  The Y positive electrode 801 and the Y negative electrode 802 have notches 821 and 822 in the center of the semi-ring shape, and when viewed from the central axis of the second movable part 300, the notches 821 and 822 have the first support part 501. , 502 overlap each other. That is, the Y positive electrode 801 and the Y negative electrode 802 do not overlap with the first support portions 501 and 502. A Y-positive wiring 811 and a Y-negative wiring 812 for transferring electric charges to the Y positive electrode 801 and the Y negative electrode 802 are provided at the top of the half ring shape.

  A constant gap is provided between the Y positive electrode 801 and the Y negative electrode 802, and the second support parts 601 and 602 overlap the gap when viewed from the central axis of the second movable part 300. That is, the Y positive electrode 801 and the Y negative electrode 802 do not overlap with the second support portions 601 and 602. In this gap, an X positive wiring 711 and an X negative wiring 712 for transferring charges to the X positive electrode 701 and the X negative electrode 702 are provided.

  The X positive / negative wirings 711 and 712 and the Y positive / negative wirings 811 and 812 are connected to a power supply device (not shown), and the first and second movable parts 200 and 300 and the frame part 400 are electrically grounded.

  First and second protrusions 721 and 722 are provided from the surfaces of the X positive electrode 701 and the X negative electrode 702 facing the first and second movable parts 200 and 300 toward the first and second movable parts 200 and 300, respectively. Provided. The first and second protrusions 721 and 722 are symmetrical with respect to the central axis of the X-direction electrode 700 and are made of an insulator.

  Next, the operation of the first movable part 200 will be described.

  First, a case where the first movable part 200 swings counterclockwise on the X axis will be described.

  A power supply device (not shown) applies an AC voltage to the X positive electrode 701 via the X positive wiring 711. This AC voltage has a maximum amplitude voltage of 40V, and a DC bias voltage of 20V is superimposed on it. Therefore, the maximum voltage is 40V and the minimum voltage is 0V (see FIG. 4).

  When the AC voltage increases from 0 V, a voltage difference is generated between the grounded first movable part 200 and the X positive electrode 701, and the first movable part 200 and the X positive electrode are caused by this voltage difference. An electrostatic force is generated between the 701 and 701. By this electrostatic force, the first movable part 200 and the X positive electrode 701 are attracted, and the first movable part 200 rotates counterclockwise on the X axis. When the AC voltage becomes maximum, the first movable part 200 rotates at the maximum rotation angle.

  When the rotation angle of the first movable part 200 increases, the first movable part 200 collides with the first protrusion 721. Since the first protrusion 721 is electrically insulated, the first movable portion 200 and the X positive electrode 701 are prevented from contacting each other, and there is no possibility that the mirror surface 201, the circuit, or the like is destroyed due to a short circuit.

  As the AC voltage decreases from 40 V, the electrostatic force decreases, and the first movable part 200 is parallel to the second movable part 300 and the frame part 400 by the elastic force of the first support parts 501 and 502. It approaches the state. When the AC voltage becomes 0 V, the potential difference between the first movable part 200 and the X positive electrode 701 disappears and the electrostatic force disappears, and the first movable part 200 includes the second movable part 300 and the frame part 400. It becomes a parallel state.

  By repeating this, the first movable part 200 swings counterclockwise on the X axis.

  Next, a case where the first movable part 200 swings clockwise around the X axis will be described.

  In this case, the power supply device applies an AC voltage to the X negative electrode 702 via the X negative wiring 712. This AC voltage is the same as when the first movable part 200 swings counterclockwise on the X axis (see FIG. 4).

  When the AC voltage increases from 0 V, a voltage difference is generated between the grounded first movable part 200 and the X negative electrode 702, and the first movable part 200 and the X negative electrode 702 are generated by this voltage difference. An electrostatic force is generated between By this electrostatic force, the first movable part 200 and the X negative electrode 702 attract each other, and the first movable part 200 rotates clockwise around the X axis. When the AC voltage becomes maximum, the first movable part 200 rotates at the maximum rotation angle.

  When the rotation angle of the first movable part 200 increases, the first movable part 200 collides with the second protrusion 722. Similar to the first protrusion 721, the second protrusion 722 prevents the mirror surface 201, the circuit, and the like from being destroyed.

  As the AC voltage decreases from 40 V, the electrostatic force decreases, and the first movable part 200 is parallel to the second movable part 300 and the frame part 400 by the elastic force of the first support parts 501 and 502. It approaches the state. When the AC voltage becomes 0 V, the potential difference between the first movable part 200 and the X negative electrode 702 disappears and the electrostatic force disappears, and the first movable part 200 includes the second movable part 300 and the frame part 400. It becomes a parallel state.

  By repeating this, the first movable part 200 swings clockwise around the X axis. As described above, since the first movable part 200 and the Y-direction electrode 800 do not overlap in the Z-axis direction, the first movable part 200 generated between the first movable part 200 and the X-direction electrode 700 is The electrostatic force for driving around the X axis does not reach the driving mechanism around the Y axis (that is, the second movable part 300 and the Y-direction electrode 800).

  Next, the operation of the second movable unit 300 will be described.

  First, the case where the second movable unit 300 swings counterclockwise in the Y axis will be described.

  A power supply device (not shown) applies an AC voltage to the Y positive electrode 801 through the Y positive wiring 811. This AC voltage has a maximum amplitude voltage of 100V, and a 50V DC bias voltage is superimposed on it. Therefore, the maximum voltage is 100V and the minimum voltage is 0V (see FIG. 5).

  When the AC voltage increases from 0 V, a voltage difference is generated between the second movable part 300 and the Y positive electrode 801 that are grounded, and the second movable part 300 and the Y positive electrode are caused by this voltage difference. An electrostatic force is generated between 801 and 801. By this electrostatic force, the second movable part 300 and the Y positive electrode 801 are attracted, and the second movable part 300 rotates counterclockwise in the Y axis. When the AC voltage becomes maximum, the second movable unit 300 rotates at the maximum rotation angle.

  When the rotation angle of the second movable part 300 increases, the top part of the second movable part 300 enters the notch of the Y positive electrode 801. Therefore, the second movable part 300 and the Y positive electrode 801 are not in direct contact. There is no possibility that a circuit or the like is destroyed due to a short circuit between the second movable part 300 and the Y positive electrode 801.

  As the AC voltage decreases from 100 V, the electrostatic force decreases and the second movable part 300 is parallel to the first movable part 200 and the frame part 400 by the elastic force of the second support parts 601 and 602. It approaches the state. When the AC voltage becomes 0 V, the potential difference between the second movable part 300 and the Y positive electrode 801 disappears and the electrostatic force disappears, and the second movable part 300 is connected to the first movable part 200 and the frame part 400. It becomes a parallel state.

  By repeating this, the second movable unit 300 swings counterclockwise in the Y axis.

  Further, since the Y positive electrode 801 does not overlap the first and second support portions, no electrostatic force is generated between the first and second support portions. Therefore, the first and second support portions do not unnecessarily swing due to the voltage applied to the Y positive electrode 801.

  A case where the second movable part 300 swings clockwise in the Y axis will be described.

  In this case, the power supply device applies an AC voltage to the Y negative electrode 802 via the Y negative wiring 812. This AC voltage is the same as that when the second movable part 300 swings counterclockwise in the Y-axis (see FIG. 5).

  When the AC voltage increases from 0 V, a voltage difference is generated between the second movable part 300 and the Y negative electrode 802 that are grounded, and the second movable part 300 and the Y negative electrode 802 are generated by this voltage difference. An electrostatic force is generated between

  By this electrostatic force, the second movable part 300 and the Y negative electrode 802 are attracted, and the second movable part 300 rotates in the Y-axis clockwise direction. When the AC voltage becomes maximum, the second movable unit 300 rotates at the maximum rotation angle.

  When the rotation angle of the second movable part 300 increases, the top of the second movable part 300 enters the notch of the Y negative electrode 802. Therefore, the second movable part 300 and the Y negative electrode 802 are not in direct contact. There is no possibility that a circuit or the like is destroyed due to a short circuit between the second movable part 300 and the Y negative electrode 802.

  As the AC voltage decreases from 100 V, the electrostatic force decreases and the second movable part 300 is parallel to the first movable part 200 and the frame part 400 by the elastic force of the second support parts 601 and 602. It approaches the state. When the AC voltage becomes 0 V, the potential difference between the second movable part 300 and the Y negative electrode 802 disappears and the electrostatic force disappears, and the second movable part 300 is connected to the first movable part 200 and the frame part 400. It becomes a parallel state.

  By repeating this, the second movable part 300 swings in the Y-axis clockwise direction. In addition, as described above, since the second movable part 300 and the X-direction electrode 700 do not overlap in the Z-axis direction, the second movable part 300 generated between the second movable part 300 and the Y-direction electrode 800 is provided. The electrostatic force for driving around the Y axis does not reach the driving mechanism around the X axis (that is, the first movable part 200 and the X direction electrode 700).

  Further, since the Y negative electrode 802 does not overlap the first and second support portions 501, 502, 601, and 602, no electrostatic force is generated between the first and second support portions 501, 502, 601, and 602. Therefore, the first and second support portions 501, 502, 601, and 602 do not unnecessarily swing due to the voltage applied to the Y negative electrode 802. That is, the electrostatic force for driving around the Y axis does not reach the driving mechanism around the X axis.

  When the voltage driven in the X-axis direction and the voltage driven in the Y-axis direction described above are superimposed, an AC voltage as shown in FIG. 6 is obtained. Conventionally, such an AC voltage has been applied to one electrode when simultaneously driving the movable part around two swing axes. In such a configuration, the DC bias component of the applied voltage becomes high, and the efficiency of the electrostatic drive type optical scanner decreases. According to the present embodiment, it is not necessary to superimpose the voltage driven in the X-axis direction and the voltage driven in the Y-axis direction and apply them to one electrode, and the applied voltage can be prevented from becoming high.

  Next, a second embodiment will be described with reference to FIG. The description of the same configuration as that of the first embodiment is omitted.

  The first and second movable parts 200 and 300, the frame part 400, the first and second support parts 601 and 602, the X-direction electrode 700, and the Y-direction electrode 800 have the same configuration as in the first embodiment. Since there is, explanation is omitted.

  X positive and negative wirings 731 and 732 extending from the X direction electrode 700 have openings 733 and 734. When viewed from the central axis of the second movable part 300, the second support parts 601 and 602 overlap the openings 733 and 734. That is, the X positive wiring 711 and the X negative wiring 712 do not overlap with the second support portions 601 and 602.

  According to the present embodiment, the X positive wiring 711 and the X negative wiring 712 do not overlap with the second support portions 601 and 602, and thus no electrostatic force is generated between the second support portions 601 and 602. Therefore, the second support portions 601 and 602 do not unnecessarily swing due to the voltage applied to the X positive wiring 711 and the X negative wiring 712.

  Note that the maximum amplitude voltage value of the AC voltage may not be 100 V or 40 V, and the DC bias component may not be 50 V or 20 V.

  The AC voltage need not be biased in the positive direction and may be biased in the negative direction.

1 is an exploded perspective view of an electrostatic drive type optical scanner according to a first embodiment. FIG. It is a front view of the 1st and 2nd movable part 300 and the 1st and 2nd support part. It is a front view of the 1st and 2nd electrode. It is the graph which showed the time change of the voltage applied to the 1st electrode. It is the graph which showed the time change of the voltage applied to the 2nd electrode. It is the graph which showed the time change of the voltage applied to the electrode by a prior art example. It is a front view of the 1st and 2nd electrode in the electrostatic drive type optical scanner by a 2nd embodiment.

Explanation of symbols

100 Electrostatically driven optical scanner (electrostatically driven actuator)
200 First movable portion 300 Second movable portion 400 Frame portion 501 First support portion 601 Second support portion 700 X direction electrode 800 Y direction electrode

Claims (6)

A first movable part;
A second movable part provided around the first movable part;
A first support portion that supports the first movable portion so as to be swingable about a first swing axis with respect to the second movable portion;
A frame portion provided around the second movable portion;
A second support portion that supports the second movable portion with respect to the frame portion so as to be swingable around a second swing shaft that is not parallel to the first swing shaft;
Provided with a certain distance from the first movable part at a position overlapping the first movable part when viewed from a straight line orthogonal to the first and second rocking axes. A first electrode that is formed;
The first support portion and the second support portion are provided at a certain distance from the second movable portion at a position overlapping the second movable portion when viewed from a straight line orthogonal to the first support portion and the second support portion. Two electrodes,
The first electrode is a first positive electrode divided by the first swing shaft when viewed from a straight line perpendicular to the first swing shaft and the second swing shaft. And a first negative electrode,
The second electrode is a second positive electrode divided by the second swing shaft when viewed from a straight line perpendicular to the first swing shaft and the second swing shaft. And an electrostatically driven actuator having a second negative electrode.   The said 1st electrode is provided in the position which does not overlap with the said 2nd movable part when it sees from the straight line orthogonal to the said 1st rocking | fluctuation axis | shaft and the said 2nd rocking | fluctuation axis | shaft. Electrostatically driven scanner.   The said 2nd electrode is provided in the position which does not overlap with the said 1st movable part when it sees from the straight line orthogonal to the said 1st rocking | fluctuation axis | shaft and the said 2nd rocking | fluctuation axis | shaft. Electrostatic drive type actuator.   2. The electrostatic drive according to claim 1, wherein the first electrode does not overlap the first support portion when viewed from a straight line orthogonal to the first swing axis and the second swing axis. Type actuator.   2. The electrostatic drive according to claim 1, wherein the second electrode does not overlap the second support portion when viewed from a straight line orthogonal to the first swing axis and the second swing axis. Type actuator.   The electrostatic drive actuator according to claim 1, wherein the first support part or the second support part is made of an elastic body.

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