JP2014006418A - Actuator - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an actuator less in deterioration in the flatness of a movable plate during displacement.SOLUTION: An actuator 100 has a fine structure 101. This fine structure 101 comprises: a movable plate 109; a movable interdigital electrode structure 105 with a plurality of interdigital electrodes 105e; a fixed interdigital electrode structure 104 with a plurality of interdigital electrodes 104e; a connection part 107 connecting the movable plate 109 and the movable interdigital electrode structure 105 in a slit form; and a torsion bar 106 supporting a movable structure formed from the movable plate 109, the movable interdigital electrode structure 105, and the connection part 107, such that the movable structure is swingable. The interdigital electrode 105e of the movable interdigital electrode structure 105 extends non-parallel with the swing shaft of the movable structure formed from the movable plate 109, the movable interdigital electrode structure 105, and the connection part 107. The interdigital electrode 105e of the movable interdigital electrode structure 105 and the interdigital electrode 104e of the fixed interdigital electrode structure 104 face each other with a space between them.

Description

  The present invention relates to an actuator driven by electrostatic force.

  An actuator driven by an electrostatic force is widely used as a power source of MEMS (Micro Electro Mechanical System), and as one of them, an actuator capable of significantly improving the displacement is disclosed in Japanese Patent Application Laid-Open No. 2010-97135. It is disclosed in the publication.

  In this actuator, a rotating plate is rotatably supported by an elastic connecting portion, and a comb-like movable electrode group is provided at an end of the rotating plate. Further, a comb-shaped fixed electrode group is provided so as to engage with the comb-shaped movable electrode group, and the fixed electrode group is arranged to be shifted downward from the movable electrode group. When a voltage is applied between the fixed electrode group and the movable electrode group, the movable electrode group is drawn between the fixed electrode groups, and as a result, the rotating plate is displaced, that is, rotated.

  Since this prior art actuator generates electrostatic attraction using a comb-shaped movable electrode group and a comb-shaped fixed electrode group, a remarkably large driving force can be obtained with a relatively small driving voltage. Therefore, it is promising for applications that require large displacement.

JP 2010-97135 A

  However, in the actuator described in Japanese Patent Application Laid-Open No. 2010-97135, the elastic connecting portion is directly connected to the rotating plate, and the movable electrode group is separated from the elastic connecting portion and directly connected to the rotating plate. Yes. For this reason, when the rotating plate is displaced, the displacement stress between the movable electrode group and the elastic connecting portion is transmitted to the rotating plate. As a result, especially when the rotating plate is relatively large and the rotating plate is largely displaced, the rotating plate is greatly bent, and the flatness of the rotating plate is greatly impaired. In a configuration in which the actuator is applied to an optical device such as an optical deflection element, the deflection of the rotating plate becomes a factor that greatly deteriorates the deflection characteristics.

  The present invention has been made in consideration of such a situation, and an object of the present invention is to provide an actuator with little deterioration in flatness of the movable plate at the time of displacement.

  An actuator according to the present invention includes a movable plate, a movable comb electrode structure having a plurality of comb electrodes, a fixed comb electrode structure having a plurality of comb electrodes, and the movable A connecting portion that connects the plate and the movable comb electrode structure in a slit shape, and a movable structure that includes the movable plate, the movable comb electrode structure, and the connecting portion is swingably supported. And a deformation portion. The comb electrodes of the movable comb electrode structure extend non-parallel to the swing axis of the movable structure, and the comb teeth of the movable comb electrode structure and the comb teeth of the fixed comb electrode structure The electrodes face each other with a gap.

  ADVANTAGE OF THE INVENTION According to this invention, the actuator with little deterioration of the flatness of the movable plate at the time of displacement is provided.

It is a top view which shows the actuator which concerns on 1st Embodiment. FIG. 2 is a cross-sectional view of the actuator taken along line A-A ′ of FIG. 1 in a non-driven state. It is sectional drawing of the actuator along the A-A 'line | wire of FIG. 1 in a drive state. It is a top view which shows the actuator which concerns on 2nd Embodiment. It is a top view which shows the actuator which concerns on 3rd Embodiment. It is a top view which shows the actuator which concerns on the modification of 3rd Embodiment. It is a top view which shows the actuator which concerns on 4th Embodiment.

  Hereinafter, embodiments will be described with reference to the drawings.

<First Embodiment>
FIG. 1 is a top view showing the actuator according to the first embodiment. As shown in FIG. 1, the actuator 100 has a fine structure 101, and the fine structure 101 includes a movable plate 109 and a movable comb electrode structure 105 having a plurality of comb electrodes 105e. A fixed comb electrode structure 104 having a plurality of comb electrodes 104e, a connecting plate 107 connecting the movable plate 109 and the movable comb electrode structure 105 in a slit shape, and a movable plate 109. A torsion bar 106, which is an elastically deformable portion that supports a movable structure composed of a movable comb electrode structure 105 and a connecting portion 107, and a rectangular frame-shaped base body 102 that supports the torsion bar 106. And a fixed comb electrode structure supporting portion 108 that connects the fixed comb electrode structure 104 and the base body 102.

  The movable plate 109 is a movable mirror, for example, and has a reflecting surface for reflecting the light beam.

  The movable comb electrode structure 105 and the fixed comb electrode structure 104 have a metal film such as Au formed on the entire surface thereof. The comb electrode 105e of the movable comb electrode structure 105 extends non-parallel to the swing axis of the movable structure composed of the movable plate 109, the movable comb electrode structure 105, and the connecting portion 107, that is, the axis of the torsion bar 106. Yes. For example, the comb electrode 105e is substantially parallel to a plane perpendicular to the axis of the torsion bar 106 from the both side surfaces of the movable comb electrode structure 105 extending substantially parallel to the axis of the torsion bar 106 to the outside. It extends to. The comb electrode 105e of the movable comb electrode structure 105 and the comb electrode 104e of the fixed comb electrode structure 104 extend substantially parallel to each other and face each other with a gap.

  Here, the connecting portion 107 “connects the movable plate 109 and the movable comb electrode structure 105 in a slit shape” means that the slit portion 103, that is, the gap between the movable plate 109 and the movable comb electrode structure 105. It means a form that is connected so that there is a constriction. The movable comb electrode structure 105 and the movable plate 109 are opposed to each other at their end faces, and the area of the end faces of the movable comb electrode structure 105 is larger than that of the movable comb electrode structure 105. The area of the cross section parallel to the end face of the tooth electrode structure 105 is formed to be smaller than the area of the end face of the movable comb electrode structure 105.

  Such a fine structure 101 is integrally formed from a polymer material such as PMAA to a thickness of about 100 μm on the same plane. A polymer material such as PMAA has a Young's modulus, which is one of mechanical properties, as small as about 1/50 compared to single crystal silicon. For this reason, a microstructure made of a polymer material can generate a larger displacement with respect to the same driving voltage than a microstructure made of single crystal silicon.

  The fixed comb electrode structure 104 is connected to the base body 102 via a plurality of fixed comb electrode structure supports 108. The fixed comb electrode structure support portions 108 are arranged with good symmetry. The fixed comb electrode structure support section 108 is disposed symmetrically with respect to the center line B-B ′ of the fixed comb electrode structure 104, for example. Each fixed comb electrode structure support 108 extends in a meandering manner between the fixed comb electrode structure 104 and the base 102, and is easily deformed in a direction perpendicular to the paper surface of FIG. .

  FIG. 2 is a cross-sectional view of the actuator taken along line A-A ′ of FIG. 1 in a non-driven state. FIG. 3 is a cross-sectional view of the actuator taken along line A-A ′ of FIG. 1 in a driving state. As shown in FIGS. 2 and 3, the actuator 100 includes a support substrate 121 that supports the microstructure 101 in addition to the microstructure 101. The support substrate 121 has a box shape and includes a peripheral wall portion 122 to which the base body 102 of the fine structure 101 is fixed. A stepped portion 123 for positioning the base body 102 is formed in the peripheral wall portion 122. The support substrate 121 also has a protrusion 124 for positioning the fixed comb electrode structure 104 on the upper surface inside the peripheral wall 122. The protrusion 124 is provided at a position aligned with the fixed comb electrode structure fixing hole 111 of the fixed comb electrode structure 104 when the base body 102 of the fine structure 101 is correctly positioned on the stepped portion 123 of the peripheral wall portion 122. It has been.

  The base 102 is fitted into the step portion 123 and fixed to the peripheral wall portion 122. Thereby, the base 102 is positioned with high accuracy. When the base body 102 is fixed to the peripheral wall portion 122, the fixed comb electrode structure support portion 108 is deformed due to the weight of the fixed comb electrode structure 104, and the fixed comb electrode structure 104 sinks and supports. It is supported in contact with the substrate 121. When the fixed comb electrode structure 104 sinks, the fixed comb electrode structure fixing hole 111 fits into the protrusion 124, so that the fixed comb electrode structure 104 is accurately positioned with respect to the base 102. Thereby, the comb-tooth electrode 105e of the movable comb-tooth electrode structure 105 and the comb-tooth electrode 104e of the fixed comb-tooth electrode structure 104 are arranged so as to face each other with no gap therebetween.

  Further, the torsion bar 106 is not easily deformed in the vertical direction in FIGS. 3 and 4, so that the movable structure including the movable plate 109, the movable comb electrode structure 105, and the connecting portion 107 is supported without sinking. The substrate 121 is supported at an interval from the inner upper surface of the peripheral wall 122.

  Next, a method for driving the actuator 100 will be described. In the state shown in FIG. 3, the movable comb electrode structure 105 is always maintained at the ground potential, and one of the fixed comb electrode structures 104, for example, the right fixed comb electrode structure 104 in FIG. When a voltage is applied, a potential difference is generated between the movable comb electrode structure 105 and the right fixed comb electrode structure 104. As a result, as shown in FIG. 4, the comb electrode 105e of the movable comb electrode structure 105 is drawn between the comb electrodes 104e of the right fixed comb electrode structure 104 by electrostatic attraction, and the movable comb teeth The electrode structure 105 is displaced or tilted in the clockwise direction, and accordingly, the movable plate 109 is displaced or tilted in the clockwise direction. Although exaggerated in FIG. 4, the movable plate 109 is largely displaced by about 5 ° in mechanical swing angle. When the positive voltage applied to the right fixed comb electrode structure 104 is periodically switched, the movable plate 109 is periodically displaced, that is, oscillated. If a positive voltage is applied to the left fixed comb electrode structure 104 instead of applying a positive voltage to the right fixed comb electrode structure 104, the movable plate 109 is displaced or tilted counterclockwise. . For example, when a positive voltage is alternately applied to the left and right fixed comb electrode structures 104, the movable plate 109 is periodically displaced, that is, oscillated with a mechanical deflection angle of about ± 5 °.

  In this actuator 100, since the movable plate 109 and the movable comb electrode structure 105 are connected in a slit shape via the connecting portion 107, the stress received when the movable comb electrode structure 105 is displaced is transmitted to the movable plate 109. Hard to do. That is, transmission of the displacement stress of the movable comb electrode structure 105 to the movable plate 109 is reduced. Thereby, the deterioration of the flatness of the movable plate 109 at the time of displacement is reduced. In other words, even when the movable plate 109 is largely displaced, good flatness of the movable plate 109 is maintained.

<Second Embodiment>
FIG. 4 is a top view showing the actuator according to the second embodiment. The actuator 200 according to the present embodiment is different from the microstructure 101 according to the first embodiment in the microstructure 201. The support substrate 221 is the same as the support substrate 121 of the first embodiment. As shown in FIG. 4, each movable comb electrode structure 205 is provided with a pair of cut portions 212 that partially define a torsion bar 206 that is continuous therewith. From another viewpoint, each movable comb electrode structure 205 is formed with a pair of cut portions 212 extending along the torsion bar 206 on both sides of the torsion bar 206. Other configurations of the fine structure 201, that is, the movable plate 209, the connecting portion 207, the movable comb electrode structure 205, the comb electrode 205e, the torsion bar 206, the base 202, the fixed comb electrode structure 204, and the comb electrode 204e The fixed comb electrode structure support section 208 includes the movable plate 109, the coupling section 107, the movable comb electrode structure 105, the comb electrode 105e, the torsion bar 106, the base body 102, and the fixed comb teeth of the first embodiment. The electrode structure 104, the comb electrode 104e, and the fixed comb electrode structure support 108 are the same. Also in this fine structure 201, the connecting portion 207 connects the movable plate 209 and the movable comb electrode structure 205 in a slit shape, that is, the slit portion 203 exists therebetween. The driving method is the same as in the first embodiment.

  By providing the notch 212 in the movable comb electrode structure 205, the connection point between the movable comb electrode structure 205 and the torsion bar 206 is shifted to the movable plate 209 side as compared with the first embodiment. Can do. Thereby, the outer dimension of the actuator 200 can be reduced without changing the size of the movable plate 209 and the length of the torsion bar 206. Further, as a result of providing the notch 212, the movable comb electrode structure 205 projects evenly on both sides of the torsion bar 206, so that the torsional deformation around the axis of the torsion bar 206 becomes more stable.

  In this actuator 200, as in the first embodiment, since the movable plate 109 and the movable comb electrode structure 105 are connected in a slit shape via the connecting portion 107, the flatness of the movable plate 109 when displaced is obtained. Degradation is reduced. Further, by providing the cut portion 212 in the movable comb electrode structure 205, the actuator 200 can be reduced in size. In addition, since the torsional deformation around the axis of the torsion bar 206 is more stable, the displacement stress of the movable comb electrode structure 205 is reduced, and the deterioration of the flatness of the movable plate 209 during the displacement is further reduced.

<Third Embodiment>
FIG. 5 is a top view showing the actuator according to the third embodiment. The actuator 300 of the present embodiment is different from the microstructure 201 of the second embodiment in the microstructure 301. The support substrate 321 is the same as the support substrate 121 of the first embodiment. As shown in FIG. 5, each movable comb electrode structure 305 has a plurality of, for example, three air holes 310. Each air hole 310 passes through the movable comb electrode structure 305 and has a rectangular shape extending in a long and thin direction parallel to the longitudinal direction of the torsion bar 306. Other configurations of the fine structure 301, that is, the movable plate 309, the connecting portion 307, the movable comb electrode structure 305, the comb electrode 305e, the torsion bar 306, the base 302, the fixed comb electrode structure 304, and the comb electrode 304e The fixed comb electrode structure support section 308 includes the movable plate 209, the coupling section 207, the movable comb electrode structure 205, the comb electrode 205e, the torsion bar 206, the base body 202, and the fixed comb teeth of the second embodiment, respectively. This is the same as the electrode structure 204, the comb electrode 204e, and the fixed comb electrode structure support 208. Also in this fine structure 301, the connecting portion 307 connects the movable plate 309 and the movable comb electrode structure 305 in a slit shape, that is, the slit portion 303 exists therebetween. Each movable comb electrode structure 305 is provided with a pair of cut portions 312 that partially define a torsion bar 306 continuous therewith. The driving method is the same as in the first embodiment.

  In this actuator 300, as in the first embodiment, since the movable plate 309 and the movable comb electrode structure 305 are connected in a slit shape via the connecting portion 307, the flatness of the movable plate 309 when displaced. Degradation is reduced. Further, by providing the notch 312 in the movable comb electrode structure 305, the actuator 300 can be reduced in size. Further, since the torsional deformation around the axis of the torsion bar 306 is more stable, the displacement stress of the movable comb electrode structure 305 is reduced. Moreover, since the air hole 310 is provided in the movable comb electrode structure 305, the displacement stress of the movable comb electrode structure 305 due to air resistance is reduced. Thereby, the deterioration of the flatness of the movable plate 309 at the time of displacement is further reduced. In addition, it contributes to speeding up the movable plate 309.

[Modification]
FIG. 6 is a top view showing an actuator according to a modification of the present embodiment. In FIG. 6, members having the same reference numerals as those shown in FIG. 5 are similar members. In the actuator 300 shown in FIG. 5, the movable comb electrode structure 305 has a small number of relatively small rectangular shapes, for example, three air holes 310. As shown in FIG. 4, the movable comb electrode structure 305 ′ has a large number of relatively small square shapes, for example, 19 air holes 310 ′. Also in the actuator 300 ′ of this modification, the same advantages as those of the actuator 300 in FIG.

<Fourth Embodiment>
FIG. 7 is a top view showing an actuator according to the fourth embodiment. The actuator 400 of this embodiment is different from the microstructure 101 of the first embodiment in the microstructure 401. The support substrate 421 is the same as the support substrate 121 of the first embodiment. As shown in FIG. 7, the movable comb electrode structure 405 has a rectangular shape and surrounds the movable plate 409 with a gap. The connecting portion 407 connects the movable comb electrode structure 405 and the movable plate 409 in a slit shape, that is, the slit portion 403 exists between them. The torsion bar 406 extends between the fixed comb electrode structure 404 and connects the rectangular base body 402 and the movable comb electrode structure 405, and the movable plate 409, the movable comb electrode structure 405, and the connecting portion. A movable structure 407 is supported so as to be swingable.

  The comb electrode 405e of the movable comb electrode structure 405 is substantially in a plane perpendicular to the axis of the torsion bar 406 outward from the portion of the movable comb electrode structure 405 extending substantially parallel to the torsion bar 406. In parallel. The comb electrode 405e of the movable comb electrode structure 405 and the comb electrode 404e of the fixed comb electrode structure 404 are opposed to each other with a gap.

  Other configurations of the fine structure 401, that is, the base 402 and the fixed comb electrode structure support portion 408 are the same as the base 102 and the fixed comb electrode structure support portion 108 of the first embodiment, respectively. The driving method is the same as in the first embodiment.

  In this actuator 400, since the movable plate 409 and the movable comb electrode structure 405 are connected in a slit shape via the connecting portion 407, the displacement stress of the movable comb electrode structure 405 is not easily transmitted to the movable plate 409. . Thereby, deterioration of the flatness of the movable plate 409 at the time of displacement is reduced. Further, since the comb electrode 405e of the movable comb electrode structure 405 is located relatively far from the axis CC ′ of the torsion bar 406, the movable plate 409 and the movable comb electrode with respect to the same drive voltage. The moment of force acting on the movable structure composed of the structure 405 and the connecting portion 407 is large. Thereby, the movable plate 409 can be displaced with a relatively small voltage. In other words, the power consumption of the actuator 400 can be reduced.

  The embodiments of the present invention have been described above with reference to the drawings. However, the present invention is not limited to these embodiments, and various modifications and changes can be made without departing from the scope of the present invention. Also good. The various modifications and changes described here include an implementation in which the above-described embodiments are appropriately combined.

  Here, the one-dimensional actuator has been described as an example, but the configuration of each embodiment can be applied to an actuator having a two-dimensional structure such as a gimbal structure. Furthermore, the present invention is not limited to a movable mirror and can be applied to an optical component having a shutter function.

DESCRIPTION OF SYMBOLS 100 ... Actuator, 101 ... Fine structure, 102 ... Base | substrate, 103 ... Slit part, 104 ... Fixed comb electrode structure, 104e ... Comb electrode, 105 ... Movable comb electrode structure, 105e ... Comb electrode, 106 DESCRIPTION OF SYMBOLS ... Torsion bar 107 ... Connection part 108 ... Fixed comb electrode structure support part 109 ... Movable plate 111 ... Fixed comb electrode structure fixing hole 121 ... Support substrate 122 ... Perimeter wall part 123 ... Step part , 124 ... projection, 200 ... actuator, 201 ... fine structure, 202 ... substrate, 203 ... slit part, 204 ... fixed comb electrode structure, 204e ... comb electrode, 205 ... movable comb electrode structure, 205e ... Comb electrode, 206 ... Torsion bar, 207 ... Connection part, 208 ... Fixed comb electrode structure support part, 209 ... Movable plate, 212 ... Cut part, 221 ... Support substrate, 3 0, 300 '... Actuator, 301 ... Fine structure, 302 ... Base, 303 ... Slit, 304 ... Fixed comb electrode structure, 304e ... Comb electrode, 305, 305' ... Movable comb electrode structure, 305e ... comb electrode, 306 ... torsion bar, 307 ... connecting part, 308 ... fixed comb electrode structure support part, 309 ... movable plate, 310, 310 '... air hole, 312 ... notch part, 321 ... support substrate, 400 ... Actuator, 401 ... Fine structure, 402 ... Base, 403 ... Slit, 404 ... Fixed comb electrode structure, 404e ... Comb electrode, 405 ... Movable comb electrode structure, 405e ... Comb electrode, 406 ... A torsion bar, 407, a connecting portion, 408, a fixed comb electrode structure supporting portion, 409, a movable plate, 421, a supporting substrate.

Claims (4)

A movable plate,
A movable comb electrode structure having a plurality of comb electrodes;
A fixed comb electrode structure having a plurality of comb electrodes;
A connecting portion connecting the movable plate and the movable comb electrode structure in a slit shape;
The movable plate, the movable comb electrode structure, and a deformable portion that supports the movable structure composed of the connecting portion in a swingable manner.
The comb electrode of the movable comb electrode structure extends non-parallel to the swing axis of the movable structure,
The actuator, wherein the comb electrode of the movable comb electrode structure and the comb electrode of the fixed comb electrode structure face each other with a gap.   2. The actuator according to claim 1, wherein the deformable portion is formed of a torsion bar, and the movable comb electrode structure is provided with a pair of cut portions that partially define the torsion bar.   The actuator according to claim 1, wherein the movable comb electrode structure is formed with air holes.   The actuator according to claim 1, wherein the movable comb electrode structure surrounds the movable plate with a gap.

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