JP2009009064A - Planar type actuator - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a planar type actuator capable of detecting the position of the moveable part by correctly measuring the shearing stress of a torsion bar without interfering the motion of the torsion bar. <P>SOLUTION: The planar type actuator comprises the frame like fixing part 2; the movable part 3 supported rotatably via the torsion bar 4 arranged inside the fixing part 2; the driving means for driving the movable part 3; piezo resistance elements 7 equipped with two pairs of electrodes 8 and arranged on the torsion bar 4 orthogonally to each other and facing each other; and the wiring parts 10 formed on the torsion bar 4 and for wiring to the electrodes formed on the fixing part 2. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a planar actuator, and more particularly to a planar actuator that pivotally supports a flat movable portion on a frame-like fixed portion and can detect the rotational position of the movable portion. .

Conventionally, as an actuator having a structure in which a plate-like movable part is pivotally supported on a frame-like fixed part, for example, using a semiconductor manufacturing technique, a silicon substrate is anisotropically etched to form a frame-like fixed part. A flat movable part and a torsion bar that pivotally supports the movable part are integrally formed on the fixed part, a drive coil is provided on the movable part, and a static magnetic field is applied to the drive coil of the movable part, for example, a static magnet such as a permanent magnet. There is an electromagnetically driven planar actuator that provides a magnetic field generating means and rotates a movable part using Lorentz force generated by the interaction between a magnetic field generated in a drive coil by energization and a static magnetic field generated by a static magnetic field generating means (For example, refer to Patent Document 1).
Such an actuator is applied to, for example, an optical scanner that deflects and scans a light beam by providing a mirror on a movable part.

  When such an actuator is applied to a scanner or the like, it is necessary to detect the mirror position, that is, the rotational position of the movable part with high accuracy. Conventionally, position detection means using a detection coil, position detection using reflected light from a laser, and the like have been disclosed as position detection means for the movable part.

However, in the position detection means using the detection coil, an induced electromotive force signal generated when the detection coil arranged on the mirror crosses the magnetic field is used. When the resonance frequency is low, the S / N ratio is low. Becomes low and cannot be applied to position detection. In addition, in the case of direct current drive, there is a problem that signal detection is difficult in principle.
On the other hand, the position detection means using the reflected light of the laser has a problem that it is difficult to reduce the size of the device and the manufacturing cost is increased.

Therefore, conventionally, even when the drive frequency is low, position detection is possible, and in order to reduce the size, a position detection element is incorporated in the torsion bar, and shear stress in the torsion bar is detected by this position detection element. Thus, there is one that detects the position of the movable part (see, for example, Patent Document 2).
Japanese Patent No. 2722314 JP 2006-85152 A

  However, since the actuator disclosed in Patent Document 2 is configured to route the wiring of the position detection element on both sides of the torsion bar, the movement of the torsion bar is hindered when the movable part rotates. As a result, the torsion bar cannot be rotated smoothly, and the shear stress of the torsion bar cannot be measured accurately.

  The present invention has been made in view of the above points, and provides a planar actuator that can accurately measure the shear stress of a torsion bar and detect the position of a movable part without hindering the movement of the torsion bar. It is for the purpose.

  In order to achieve the above object, an planar type actuator according to the first aspect of the present invention includes a frame-shaped fixed portion, a movable portion that is rotatably supported inside the fixed portion via a torsion bar, Driving means for driving the movable part, a piezoresistive element having two pairs of electrodes arranged on the torsion bar and facing each other in a direction substantially perpendicular to each other, and an electrode formed on the torsion bar and formed on the fixed part And a wiring portion that is routed around the portion.

  According to a second aspect of the present invention, in the first aspect, the piezoresistive element is arranged in the vicinity of a position where the shear stress on each surface of the torsion bar is the largest.

  According to a third aspect of the present invention, in the first or second aspect, the torsion bar is formed of an n-type single crystal silicon material, the piezoresistive element is formed of a p-type region, and the piezoresistor is formed. The element includes a pair of the electrodes of the piezoresistive element in a range of ± 30 ° with respect to the <100> axis in the (100) plane or (110) plane of the n-type single crystal silicon material constituting the torsion bar. It is arranged so that the connecting direction is substantially parallel.

  According to a fourth aspect of the present invention, in the first or second aspect, the torsion bar is made of a p-type single crystal silicon material, the piezoresistive element is formed of an n-type region, and the piezoresistor is formed. The element includes a pair of the electrodes of the piezoresistive element in a range of ± 30 ° with respect to the <110> axis in the (100) plane or the (110) plane of the p-type single crystal silicon material constituting the torsion bar. It is arranged so that the connecting direction is substantially parallel.

  According to a fifth aspect of the present invention, in any one of the first to fourth aspects, the piezoresistive element is formed in a substantially cross shape in a planar shape, and the electrode is disposed at a tip portion thereof. It is characterized by.

  A sixth aspect of the present invention is characterized in that in any one of the first to fifth aspects, a plurality of the piezoresistive elements are provided, and the piezoresistive elements are connected in series. To do.

  A seventh aspect of the invention is characterized in that in any one of the first to fifth aspects, a plurality of the piezoresistive elements are provided, and the piezoresistive elements are integrally formed. .

  According to an eighth aspect of the present invention, in any one of the first to fourth aspects, the piezoresistive element is formed in a substantially rectangular shape in a planar shape, and the electrodes are arranged at the four corners. Features.

  According to a ninth aspect of the present invention, in any one of the first to fourth aspects, each electrode of the piezoresistive element is disposed so as to be inclined at a predetermined angle with respect to a longitudinal direction of the torsion bar. It is characterized by.

  According to the actuator of the first aspect of the present invention, the piezoresistive element and the wiring part are respectively installed on the torsion bar, and the piezoresistive element detects the shear stress applied to the torsion bar by the rotating operation of the movable part. Since the rotational position of the movable part is detected, the position of the movable part can be detected by accurately measuring the shear stress of the torsion bar without hindering the movement of the torsion bar.

  According to the second aspect of the present invention, since the piezoresistive element is arranged in the vicinity of the position where the shear stress on each surface of any one of the torsion bars is maximized, the sensitivity of detecting the shear stress of the torsion bar is remarkably increased. The shear stress of the torsion bar can be detected efficiently.

  According to the invention described in claim 3, the piezoresistive element has a range of ± 30 ° with respect to the <100> axis in the (100) plane or (110) plane of the n-type single crystal silicon material constituting the torsion bar. Furthermore, since the direction connecting the pair of electrodes of the piezoresistive element is arranged substantially parallel, the detection sensitivity of the torsion bar shear stress can be remarkably increased, and the torsion bar shear stress can be detected efficiently. can do.

  According to the invention of claim 4, the piezoresistive element has a range of ± 30 ° with respect to the <100> axis in the (100) plane or (110) plane of the p-type single crystal silicon material constituting the torsion bar. Furthermore, since the direction connecting the pair of electrodes of the piezoresistive element is arranged in parallel, the detection sensitivity of the torsion bar shear stress can be remarkably increased, and the torsion bar shear stress can be detected efficiently. Can do.

  According to the invention described in claim 5, since the piezoresistive element is formed in a substantially cross shape in a planar shape and an electrode is disposed at the tip thereof, the shear of the torsion bar can be prevented without hindering the movement of the torsion bar. The position of the movable part can be detected by accurately measuring the stress.

  According to the sixth aspect of the present invention, since a plurality of piezoresistive elements are provided and each piezoresistive element is connected in series, detection is performed with higher sensitivity without hindering the movement of the torsion bar. It becomes possible.

  According to the seventh aspect of the present invention, a plurality of piezoresistive elements are provided, and each piezoresistive element is integrally formed, so that detection can be performed with higher sensitivity without hindering the movement of the torsion bar. Is possible.

  According to the eighth aspect of the present invention, since the piezoresistive element is formed in a substantially square shape with electrodes arranged at the four corners, the shear stress of the torsion bar is not hindered. Can be accurately measured to detect the position of the movable part.

  According to the ninth aspect of the present invention, each electrode of the piezoresistive element is arranged so as to be inclined at a predetermined angle with respect to the longitudinal direction of the torsion bar, so that the shear stress of the material constituting the torsion bar is When the maximum direction is inclined at a predetermined angle with respect to the longitudinal direction of the torsion bar, the electrode of the piezoresistive element can be appropriately disposed at a position where the shear stress is maximized.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is a plan view showing an embodiment of a planar actuator according to the present invention.
The planar actuator according to the present embodiment deflects a light beam from a light source (not shown), and is manufactured by applying, for example, semiconductor micromachine technology.

  As shown in FIG. 1, the planar actuator 1 of the present embodiment includes a frame-shaped fixed portion 2, and the movable portion 3 is located inside the fixed portion 2 with a predetermined gap with respect to the fixed portion 2. It is arranged with. The fixed portion 2 and the movable portion 3 are connected to each other by a pair of torsion bars 4 and 4 extending inward from the substantially central portion of opposite sides of the fixed portion 2, and are movable via the torsion bar 4. The part 3 is rotatably supported. The fixed portion 2, the torsion bar 4 and the movable portion 3 are configured to be integrally formed.

A reflection mirror 5 for deflecting the light beam from the light source by the rotating operation of the movable part 3 is provided on the entire rear surface side (back side of the paper surface) of the movable part 3.
A drive coil (not shown) for driving the movable part 3 is provided on the peripheral edge on the surface side of the movable part 3, and opposite magnetic poles are opposed to each other with the movable part 3 sandwiched on both sides of the fixed part 2. A pair of static magnetic field generating members 6 and 6 are arranged. The static magnetic field generating member 6 may be a permanent magnet or an electromagnet.

  As shown in FIGS. 1 and 2, in the present embodiment, piezoresistive elements 7 and 7 are respectively installed on the upper surface of each torsion bar 4. The piezoresistive element 7 detects a shear stress applied to the torsion bar 4 by the rotating operation of the movable portion 3, and an output voltage proportional to the shear stress is generated in a direction orthogonal to the direction in which the voltage is applied. It uses the principle.

As shown in FIG. 3, the piezoresistive element 7 is formed in a substantially cross shape with a planar shape in which one length dimension is longer than the other length dimension. Electrodes 8, 8... Are arranged respectively. In the piezoresistive element 7, the direction connecting the pair of electrodes 8, 8 located at the distal end in the longitudinal direction, that is, the longitudinal direction of the piezoresistive element 7 is parallel to the direction in which the shear stress of the material constituting the torsion bar 4 is maximized. It is comprised so that it may be arrange | positioned in the position vicinity which becomes In the present embodiment, the piezoresistive element 7 is installed on the upper surface of the torsion bar 4. However, if the shear stress on each surface of the torsion bar is near the position where the shear stress is the largest, the side surface of the torsion bar 4 is used. It may be installed on any surface such as the back surface.
Here, in the shear type piezoresistive element, when a shear stress is generated in the piezoresistive element, an output voltage proportional to the shear stress is generated in a direction orthogonal to the direction in which the voltage is applied. The direction of the stress is a direction orthogonal to the applied voltage.

And the relational expression of applied voltage, shear stress, and output voltage can be expressed by the following expression.
Vo = Wτπ / L * Vin
here,
L: Length dimension in the longitudinal direction of the piezoresistive element W: Width dimension of the longest portion in the longitudinal direction of the piezoresistive element τ: Shear stress acting on the piezoresistive element π: Piezoresistive coefficient Vin: Input voltage Vo: Output voltage is there.
Therefore, it can be seen that the output voltage increases as W / L increases.

On the other hand, when π in the (100) plane is calculated for the piezoresistance effect in the cubic system (Si), it is as shown in FIG.
According to this result, it can be seen that the piezoresistance coefficient has a maximum value in the <100> direction. And, if it is within a range of ± 30 ° with respect to the <100> axis (meaning −30 ° to + 30 ° with respect to the <100> axis, the same applies hereinafter), a piezoresistance coefficient having a certain size. It is preferable that a larger piezoresistance coefficient can be obtained in the range of ± 15 ° with respect to the <100> axis, and most preferably in the range of ± 5 ° with respect to the <100> axis. I understand.

Therefore, when the torsion bar 4 is formed of an n-type single crystal silicon material and the piezoresistive element 7 is formed of a p-type region, the piezoresistive element 7 has a shear stress on each surface of the torsion bar 4. What is necessary is just to arrange | position in the position vicinity where becomes large. Specifically, a range of ± 30 ° with respect to the <100> axis in the (100) plane or (110) plane, preferably ± 15 ° with respect to the <100> axis in the (100) plane or (110) plane. , Most preferably in the range of ± 5 ° with respect to the <100> axis in the (100) plane or (110) plane. In this specification, a range of ± 5 ° with respect to the <100> axis in the (100) plane or the (110) plane is described as being substantially parallel to the <100> axis.
When the torsion bar 4 is formed of a p-type single crystal silicon material and the piezoresistive element 7 is formed of an n-type region, the (100) plane or (110) ) Plane within the range of ± 30 ° with respect to the <110> axis, preferably within the range of ± 15 ° with respect to the <110> axis of the (100) plane or the (110) plane, most preferably the (100) plane. Or it installs in the range of +/- 5 degree with respect to the <110> axis | shaft in (110) plane.
In the (111) plane, since the value of π is constant regardless of the direction, the direction of the piezoresistive element is arbitrary.

  In the present embodiment, when the torsion bar 4 is formed of an n-type single crystal silicon material and the piezoresistive element 7 is formed of a p-type region, the n-type single crystal silicon constituting the torsion bar 4 is used. The piezoresistive element 7 is arranged so that the longitudinal direction thereof is substantially parallel to the <100> axis of the material. In the present embodiment, an example in which the <100> axis is located along the longitudinal direction of the torsion bar 4 is shown, and the longitudinal direction of the piezoresistive element 7 is parallel to the longitudinal direction of the torsion bar 4. It is arranged as follows.

An electrode terminal 9 is formed on the surface of the fixed portion 2, and a wiring portion 10 that is connected to the electrode terminal 9 through the surface of the torsion bar 4 is connected to each electrode 8 of the piezoresistive element 7. ing.
The wiring portion 10 may be formed on any surface such as the top surface or the side surface of the torsion bar 4.

Next, a method for manufacturing the planar actuator 1 of this embodiment will be described.
First, on the surface of an SOI (Silicon On Insulator) wafer 11) joined by sandwiching a thermal oxide film layer 11b between two single crystal silicon wafers 11a and 11c shown in FIG. 5, as shown in FIG. Then, the silicon oxide film 12 is coated using an oxidation furnace or the like. Thereafter, as shown in FIG. 7, a piezoresistive element 7 is formed at a predetermined position corresponding to the torsion bar 4 by ion implantation or thermal diffusion. As a means for forming this piezoresistive element 7, for example, when the single crystal silicon wafer 11a is formed of an n-type single crystal silicon material, an impurity is added to the n-type single crystal silicon material, for example. A mold region may be formed, or a p-type single crystal silicon material may be prepared in a separate process, and the p-type single crystal silicon material may be attached to a torsion bar. Even when the single crystal silicon wafer 11a is formed of a p-type single crystal silicon material, the piezoresistive element 7 may be formed by the same means.

  Then, as shown in FIG. 8, a silicon oxide film 12 is formed on the surface of the piezoresistive element 7 using, for example, an oxidation furnace. Thereafter, as shown in FIG. 9, the silicon oxide film 12 is etched by masking portions other than the electrode lead-out contact portion to the piezoresistive element 7 to form the contact 13.

  Then, as shown in FIG. 10, the positive resist resists the portions other than those corresponding to the input and output electrodes 8, the planar coil (not shown) and the electrode terminals 9 of the piezoresistive element 7, and performs aluminum etching. Then, the wiring part 10 is formed. Then, as shown in FIG. 11, in order to protect the wiring part 10, for example, the wiring part 10, the planar coil, and the electrode 8 are covered with an insulating film 14 such as photosensitive polyimide.

Although not shown, for example, an aluminum thin film is formed on the silicon oxide film 12 by sputtering or the like, as in the prior art. Next, a portion corresponding to a drive coil (not shown) and a pair of electrode terminal regions (not shown) is masked with a positive resist, the aluminum thin film is etched, and then the positive resist is removed. Then, the drive coil portion is coated with an interlayer insulating film such as photosensitive polyimide. Further, an aluminum thin film is formed by sputtering or the like, the portion connecting the drive coil and the pair of electrode terminal regions is masked with a positive resist, the aluminum thin film is etched, and then the positive resist is removed. Then, the drive coil portion and the portion connecting the drive coil and the pair of electrode terminal regions are coated with a protective film such as photosensitive polyimide. Finally, the portions of the SOI wafer 11 excluding the fixing portion 2, the torsion bar 4 and the driving portion 3 are removed by etching, and the static magnetic field generating member 6 is attached at a predetermined position.
Through the above process, the piezoresistive element 7 is formed in the planar actuator 1.

  Next, the operation of this embodiment will be described.

  The driving principle of the planar actuator 1 is described in detail in, for example, Japanese Patent No. 2722314, and will be briefly described below.

  When a current is passed through the drive coil of the movable part 3, a magnetic field is generated, and a Lorentz force is generated by the interaction between this magnetic field and the static magnetic field generated by the static magnetic field generating means, and the movable part 3 is parallel to the axial direction of the torsion bar 4. Rotational forces in opposite directions are generated on opposite sides, and the movable part 3 is rotated to a position where the rotational force and the restoring force of the torsion bar 4 are balanced.

  Then, by passing a direct current through the drive coil, the movable part 3 is stopped at a rotation position corresponding to the amount of drive current, whereby the light beam can be deflected in a desired direction by the reflection mirror 5.

  On the other hand, when an alternating current is passed through the drive coil, the movable part 3 swings and the light beam can be deflected and scanned by the reflection mirror 5. Since the rotational force for rotating the movable part 3 is proportional to the drive current value flowing through the drive coil, the deflection angle of the movable part 3 (deflection of the light beam) is controlled by controlling the drive current value supplied to the drive coil. Angle) can be controlled.

  Then, the shear stress applied to the torsion bar 4 by the rotating operation of the movable portion 3 is detected by the piezoresistive element 7, and the output voltage generated in proportion to the shear stress is output from the electrode terminal 9 via the wiring portion 10. Thus, the amount of rotation of the movable part 3 is detected.

  Therefore, in this embodiment, the piezoresistive element 7 and the wiring part 10 are respectively installed on the torsion bar 4, and the piezoresistive element 7 detects the shear stress applied to the torsion bar 4 by the rotating operation of the movable part 3. Since the rotational position of the movable part 3 is detected, the position of the movable part 3 can be detected by accurately measuring the shear stress of the torsion bar 4 without hindering the movement of the torsion bar 4. it can.

  In addition, the piezoresistive element 7 is formed in the vicinity of the position where the shear stress of the material constituting the torsion bar 4 becomes the largest, specifically, the torsion bar 4 is formed of an n-type single crystal silicon material, and the piezoresistive element When 7 is formed of a p-type region, it is arranged so that the longitudinal direction of the piezoresistive element 7 is substantially parallel to the <100> axis of the n-type single crystal silicon material constituting the torsion bar 4. Therefore, the sensitivity of detecting the shear stress of the torsion bar 4 can be remarkably increased, and the shear stress of the torsion bar 4 can be detected efficiently.

  In the present embodiment, the example in which the wiring portion 10 is routed from each electrode 8 of the piezoresistive element 7 has been described. However, for example, when the piezoresistive element 7 is formed as shown in FIG. By forming an insulating layer (not shown), a part of the wiring part 10 may be arranged so as to overlap the piezoresistive element 7.

  Moreover, in the said embodiment, although the length shape of one side was formed longer than the length dimension of the other, the example formed in the planar shape substantially cross shape was demonstrated, as shown in FIG. 13, both length dimensions are shown. May be formed into a planar cross shape that is equally formed. In this case, as described above, the larger the W / L, the higher the output voltage. Therefore, the shorter the L, the better the sensitivity, which is preferable.

  Furthermore, as shown in FIG. 14, a plurality (two in this example) of piezoresistive elements 7 may be provided, and these piezoresistive elements 7 may be connected in series. Detection can be performed. Further, as shown in FIG. 15, a plurality (three in this example) of piezoresistive elements 7 may be integrally formed in series.

  Further, as shown in FIG. 16, the piezoresistive element 7 may be formed in a planar square shape, and electrodes 8 may be arranged at the four corners. It can be applied as a bridge resistance pattern in which a resistor is provided.

  In addition, as shown in FIG. 17, each electrode 8 of the piezoresistive element 7 may be arranged to be inclined at a predetermined angle with respect to the longitudinal direction of the torsion bar 4. With this configuration, when the <100> axis of the single crystal silicon material constituting the torsion bar 4 is inclined at a predetermined angle with respect to the longitudinal direction of the torsion bar 4, the electrode 8 of the piezoresistive element 7 is used. Can be arranged substantially parallel to the <100> axis of the single crystal silicon material.

  In the present embodiment, the electromagnetic drive actuator has been described. However, the present invention is not limited to this drive method, and it is needless to say that the drive method such as an electrostatic method, a piezoelectric method, and a heat method can be applied. In the present embodiment, an example of a one-dimensional planar actuator has been described. However, a two-dimensional planar actuator may be used. Further, in the present embodiment, the fixed portion 2, the torsion bar 4 and the drive portion 3 are integrally formed of a silicon material, but the piezoresistive element 7 of the torsion bar 4 is made of silicon if it has a piezoresistance effect. For example, a piezoelectric element such as lead zirconate titanate (PZT) may be formed. Further, the fixed portion 2, the torsion bar 4 and the movable portion 3 may be formed of different materials, or may be formed of separate members instead of being integrated and formed in combination.

1 is a schematic plan view showing an embodiment of a planar actuator according to the present invention. It is an enlarged view of the piezoresistive element part of FIG. It is explanatory drawing of the piezoresistive element in this invention. It is a graph which shows the result of having calculated the piezoresistance coefficient in (100) plane in the piezoresistive element in this invention. It is explanatory drawing which shows the manufacturing method of the planar type actuator of this embodiment. It is explanatory drawing which shows the silicon oxide film formation state in the manufacturing method of the planar type actuator of this embodiment. It is explanatory drawing which shows the piezoresistive element formation state in the manufacturing method of the planar type actuator of this embodiment. It is explanatory drawing which shows the silicon oxide film formation state of the piezoresistive element part in the manufacturing method of the planar type actuator of this embodiment. It is explanatory drawing which shows the contact formation state in the manufacturing method of the actuator of this embodiment. It is explanatory drawing which shows the wiring part formation state in the manufacturing method of the planar type actuator of this embodiment. It is explanatory drawing which shows the insulating film formation state in the manufacturing method of the planar type actuator of this embodiment. It is a partial top view which shows the modification of the piezoresistive element in the planar type actuator of this invention. It is a partial top view which shows the other modification of the piezoresistive element in the planar type actuator of this invention. It is a partial top view which shows the other modification of the piezoresistive element in the planar type actuator of this invention. FIG. 10 is a partial plan view showing still another modification of the piezoresistive element in the planar actuator of the present invention. It is a partial top view which shows the other modification of the piezoresistive element in the planar type actuator of this invention. FIG. 10 is a partial plan view showing still another modification of the piezoresistive element in the planar actuator of the present invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Planar type actuator 2 Fixed part 3 Movable part 4 Torsion bar 5 Reflection mirror 6 Static magnetic field generating member 7 Piezoresistive element 8 Electrode 9 Electrode terminal 10 Wiring part 11 SOI wafer 12 Silicon oxide film 13 Contact 14 Insulating film

Claims (9)

A frame-shaped fixing part;
Inside this fixed part, a movable part rotatably supported via a torsion bar,
Drive means for driving the movable part;
A piezoresistive element having two pairs of electrodes disposed in the torsion bar and facing each other in a direction substantially perpendicular to each other;
A wiring part formed on the torsion bar and routed to an electrode part formed on the fixing part;
A planar actuator characterized by comprising: 2. The planar actuator according to claim 1, wherein the piezoresistive element is disposed in the vicinity of a position where the shear stress on each surface of any one of the torsion bars is maximized. The torsion bar is made of an n-type single crystal silicon material, and the piezoresistive element is formed of a p-type region,
The piezoresistive element has a pair of piezoresistive elements in a range of ± 30 ° with respect to the <100> axis on the (100) plane or (110) plane of the n-type single crystal silicon material constituting the torsion bar. The planar actuator according to claim 1, wherein the electrodes are arranged so that directions in which the electrodes are connected are substantially parallel. The torsion bar is made of a p-type single crystal silicon material, and the piezoresistive element is formed of an n-type region.
The piezoresistive element has a pair of piezoresistive elements in a range of ± 30 ° with respect to the <110> axis in the (100) plane or (110) plane of the p-type single crystal silicon material constituting the torsion bar. The planar actuator according to claim 1, wherein the electrodes are arranged so that directions in which the electrodes are connected are substantially parallel.   The planar type actuator according to any one of claims 1 to 4, wherein the piezoresistive element is formed in a substantially cross shape in a planar shape, and the electrode is disposed at a tip portion thereof.   The planar actuator according to any one of claims 1 to 5, further comprising a plurality of the piezoresistive elements, wherein each of the piezoresistive elements is connected in series.   The planar actuator according to any one of claims 1 to 5, further comprising a plurality of the piezoresistive elements, wherein the piezoresistive elements are integrally formed.   5. The planar actuator according to claim 1, wherein the piezoresistive element is formed in a substantially square shape in a planar shape, and the electrodes are arranged at the four corners.   5. The planar according to claim 1, wherein each electrode of the piezoresistive element is arranged to be inclined at a predetermined angle with respect to a longitudinal direction of the torsion bar. Type actuator.

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