Actuator device and mirror drive device

A torsion bar portion is of a meandering shape including a plurality of straight sections and a plurality of turnover sections. The plurality of straight sections extends in a first direction along a swing axis and is juxtaposed in a second direction intersecting with the first direction. The plurality of turnover sections alternately couples two ends of the straight sections. Wiring is disposed on the torsion bar portion. The wiring includes first wiring sections and second wiring sections. The first wiring sections include damascene wiring sections that are disposed so as to be embedded in grooves formed in the turnover sections and that are made of a first metal material including Cu. The second wiring sections are disposed on the straight sections and are made of a second metal material more resistant to plastic deformation than the first metal material.

TECHNICAL FIELD

The present invention relates to an actuator device and a mirror driving device.

BACKGROUND ART

Known actuator devices include a support portion, a movable portion with a coil thereon, a magnetic field generating portion is configured to let a magnetic field be exerted on the coil, and torsion bar portions on which wiring connected to the coil is disposed and that couple the movable portion to the support portion so as to be swingable (e.g., cf. Patent Literature 1). The torsion bar portions are of a meandering shape including a plurality of straight sections and a plurality of turnover sections. The plurality of straight sections extends in a first direction along a swing axis of the torsion bar portions and is juxtaposed in a second direction intersecting with the first direction. The plurality of turnover sections alternately couples two ends of the plurality of straight sections.

CITATION LIST

Patent Literature

SUMMARY OF INVENTION

Technical Problem

An object of the present invention is to provide an actuator device and a mirror driving device capable of achieving reduction in resistance of the wiring and preventing the wiring from inhibiting swing motion of the movable portion.

Solution to Problem

The Inventors conducted investigation research and found the new fact as described below.

When the torsion bar portions are of the aforementioned meandering shape, the wiring disposed on the torsion bar portions includes wiring sections disposed on the respective turnover sections and wiring sections connected to the foregoing wiring sections and disposed on the respective straight sections. The wiring sections disposed on the turnover sections have higher resistance than the wiring sections disposed on the straight sections, because of their shape. For this reason, the wiring sections disposed on the turnover sections have high resistance in the entire wiring. With high resistance of wiring, the wiring generates heat and it becomes difficult to ensure a sufficient amount of electric current to be supplied to the coil. If the sufficient amount of electric current to the coil is not ensured, a swing range of the movable portion decrease.

By adopting a configuration in which the wiring is damascene wiring made of copper (Cu), it is possible to significantly decrease the total resistance of the wiring disposed on the torsion bar portions. However, when the wiring is the damascene wiring made of Cu, the wiring may inhibit the swing motion of the movable portion.

In the case of the torsion bar portions of the meandering shape as described above, when the movable portion swings around the swing axis of the torsion bar portions, high stress is exerted on the straight sections extending in the first direction along the swing axis of the torsion bar portions. For this reason, for example, when the movable portion swings in one direction around the swing axis of the torsion bar portions, the high stress is exerted on the damascene wiring of Cu located on the straight sections, so as to cause plastic deformation of the damascene wiring of Cu itself. In the plastic deformation state of the wiring (damascene wiring), the movable portion could fail to return to an initial position, or, the movable portion could be subjected to mechanical resistance during swing motion in the direction opposite to the foregoing one direction around the swing axis of the torsion bar portions.

The Inventors conducted elaborate research on configurations capable of achieving reduction in resistance of the wiring and preventing the wiring from inhibiting the swing motion of the movable portion.

As a result of the research, the Inventors have come to discover a configuration capable of suppressing the plastic deformation of the wiring sections located on the straight sections. In this configuration, the wiring sections disposed on the straight sections where the high stress is exerted on are not the damascene wiring made of Cu, but they are wiring made of a metal material more resistant to plastic deformation than Cu.

The Inventors focused on the point that the stress exerted on the turnover sections is lower than that on the straight sections. The Inventors have come to consider that the resistance of the wiring could be reduced by adopting a configuration in which the wiring sections disposed on the turnover sections were the damascene wiring made of Cu. The wiring sections disposed on the turnover sections have relatively high resistance because of their shape, as described above. For this reason, when the wiring sections disposed on the turnover sections are the damascene wiring made of Cu, the resistance of the wiring can be kept low.

An actuator device according to one aspect of the present invention includes a support portion, a movable portion on which a conductor is disposed, and a torsion bar portion on which wiring connected to the conductor is disposed and that couples the movable portion to the support portion so as to be swingable. The torsion bar portion is of a meandering shape including a plurality of straight sections extending in a first direction along a swing axis of the torsion bar portion and juxtaposed in a second direction intersecting with the first direction, and a plurality of turnover sections alternately coupling two ends of the straight sections. The wiring includes first wiring sections disposed on the respective turnover sections and second wiring sections connected to the first wiring sections and disposed on the respective straight sections. The first wiring sections include damascene wiring sections that are disposed so as to be embedded in grooves formed in the turnover sections and that are made of a first metal material including Cu. The second wiring sections are disposed on the straight sections and are made of a second metal material more resistant to plastic deformation than the first metal material.

In the actuator device according to the one aspect of the present invention, the first wiring sections disposed on the turnover sections include the damascene wiring sections made of the first metal material including Cu. For this reason, it is feasible to achieve reduction in resistance of the wiring disposed on the torsion bar portion. The second wiring sections disposed on the straight sections are made of the second metal material more resistant to plastic deformation than the first metal material. For this reason, the plastic deformation of the second wiring sections is suppressed even in a situation where high stress is exerted on the straight sections. Therefore, it is feasible to prevent the wiring disposed on the torsion bar portion from inhibiting the swing motion of the movable portion.

The first wiring section may further include a section that is disposed on the damascene wiring section so as to cover an opening of the groove and that is made of the second metal material. In this case, the resistance of the first wiring section can be further reduced.

In the damascene wiring section, the corner edges located on the surface side of the turnover section may be locally thinned so as to reduce the sectional area because of steps in its manufacturing process. The decrease in sectional area of the damascene wiring section leads to increase in resistance of the first wiring section. However, since the first wiring section includes the section disposed on the damascene wiring section so as to cover the opening of the groove, the increase in resistance of the first wiring section can be prevented even if the damascene wiring section is thinned.

A connection point between the torsion bar portion and the support portion and a connection point between the torsion bar portion and the movable portion may be located on a virtual line passing through a central region in the second direction of the torsion bar portion and extending in the first direction.

The resonance frequency of the torsion bar portion is determined by the width of the torsion bar portion and the length in the first direction of the torsion bar portion. A conceivable configuration to decrease the stress exerted on the straight sections is to increase the number of straight sections. The straight sections are not juxtaposed in the first direction but juxtaposed in the second direction. For this reason, there is no change in the length in the first direction of the torsion bar portion, even with increase in the number of straight sections. Therefore, it facilitates design of the torsion bar portion for setting the resonance frequency of the torsion bar portion to a desired value.

The torsion bar portion may further include a first connection section that connects the support portion to one straight section located outermost in the second direction out of the plurality of straight sections, and a second connection section that connects the movable section to the other straight section located outermost in the second direction out of the plurality of straight sections, and the wiring may further include third wiring sections that are connected to the first wiring sections and that are disposed on the first and second connection sections, respectively.

The third wiring sections may include damascene wiring sections that are disposed so as to be embedded in grooves formed in the first and second connection sections, respectively, and that are made of the first metal material. In this case, even though the wiring includes the third wiring sections, increase in resistance of the wiring is suppressed. As a result, the reduction in resistance of the wiring can be surely achieved.

The second metal material may include Al or an alloy containing Al. In this case, plastic deformation of the second wiring sections can be suppressed quite well.

The movable portion may include a first section to which the torsion bar portion is coupled, and a second section supported on the first section so as to be swingable around a swing axis extending in a direction orthogonal to the swing axis of the torsion bar portion. In this case, the second section of the movable portion can be swung around each of the two orthogonal axes.

A coil as the conductor may be disposed on the movable portion, and the actuator device may further include a magnetic field generating portion is configured to let a magnetic field be exerted on the coil. In this case, the movable portion can be swung by letting an electric current flow through the coil on which the magnetic field is exerted.

A mirror driving device according to one aspect of the present invention is a mirror driving device including the foregoing actuator device and a mirror disposed on the movable portion.

The mirror driving device according to the one aspect of the present invention can achieve reduction in resistance of the wiring disposed on the torsion bar portion and can prevent the wiring disposed on the torsion bar portion from inhibiting the swing motion of the movable portion, as described above.

Advantageous Effects of Invention

According to the above-described aspects of the present invention, the actuator device and the mirror driving device are provided as those capable of achieving the reduction in resistance of the wiring and preventing the wiring from inhibiting the swing motion of the movable portion.

DESCRIPTION OF EMBODIMENTS

Embodiments of the present invention will be described below in detail with reference to the accompanying drawings. It is noted that in the description the same elements or elements with the same functionality will be denoted by the same reference signs, without redundant description.

A configuration of a mirror driving device1according to the present embodiment will be described with reference toFIGS. 1 to 3.FIG. 1is a perspective view showing the mirror driving device according to the present embodiment.FIG. 2is a top plan view of the mirror driving device shown inFIG. 1.FIG. 3is a drawing for illustrating a circuit in the mirror driving device shown inFIG. 1.

As shown inFIGS. 1 to 3, the mirror driving device1includes an actuator device2and a mirror3. The actuator device2includes a magnetic field generating portion4, a support portion6, a movable portion8, and a pair of torsion bar portions10.

The mirror3is a light reflecting film constituting a metal thin film. The mirror3is of a circular shape on its planar view. A metal material to be used for the mirror3can be, for example, aluminum (Al), gold (Au), or silver (Ag).

The magnetic field generating portion4is a flat plate of a rectangular shape. The magnetic field generating portion4includes a pair of principal faces4a,4b(not shown). The magnetic field generating portion4lets a magnetic field be exerted on the movable portion8. Arrangement of magnetic poles adopted for the magnetic field generating portion4is a Halbach array. The magnetic field generating portion4is made, for example, of permanent magnets or the like.

The support portion6is a frame body with an outside contour of a rectangular shape. The support portion6is disposed on the magnetic field generating portion4so as to be opposed to the principal face4athereof. The support portion6supports the movable portion8through the pair of torsion bar portions10. The movable portion8is located inside the support portion6. The movable portion8includes a first movable portion81, a second movable portion82, and a mirror arrangement portion83. In the present embodiment, the support portion6, movable portion8, and torsion bar portions10are integrally formed and are made, for example, of silicon (Si).

The first movable portion81is located inside the support portion6and is a frame body of a flat plate shape with an outside contour of a rectangular shape. The first movable portion81is coupled to the torsion bar portions10and is disposed as separated from the support portion6. The first movable portion81is supported so as to be swingable on the support portion6through the pair of torsion bar portions10. Namely, the first movable portion81is supported so as to be rotatable back and forth on the support portion6through the pair of torsion bar portions10. Each torsion bar portion10couples the first movable portion81to the support portion6so as to be swingable. The first movable portion81includes a principal face opposed to the magnetic field generating portion4, and a principal face81athat is a back side with respect to the foregoing principal face. Each torsion bar portion10is of a meandering shape, as described below.

The second movable portion82is located inside the first movable portion81and is a frame body of a flat plate shape with an outside contour of a rectangular shape. The second movable portion82is disposed as separated from the first movable portion81. The second movable portion82is supported so as to be swingable on the first movable portion81through a pair of torsion bar portions14. Namely, the second movable portion82is supported so as to be rotatable back and forth on the first movable portion81through the pair of torsion bar portions14. Each torsion bar portion14couples the second movable portion82to the first movable portion81so as to be swingable. The second movable portion82also includes a principal face opposed to the magnetic field generating portion4, and a principal face82athat is a back side with respect to the foregoing principal face as the first movable portion81includes. Each torsion bar portion14is of a straight shape and is located on an identical straight line. In the present embodiment, the torsion bar portions14are also formed integrally with the support portion6, movable portion8, and torsion bar portions10and are made, for example, of Si.

A swing axis of the torsion bar portions10intersects with a swing axis of the torsion bar portions14. In the present embodiment, the swing axis of the torsion bar portions10is orthogonal to the swing axis of the torsion bar portions14. Namely, a rotational axis of the torsion bar portions10intersects with a rotational axis of the torsion bar portions14. The second movable portion82is supported on the first movable portion81so as to be swingable around the swing axis extending in the direction orthogonal to the swing axis of the torsion bar portions10.

The mirror arrangement portion83is located inside the second movable portion82and is of a circular shape. The mirror arrangement portion83is integrated with the second movable portion82and swung integrally with the second movable portion82. The mirror arrangement portion83includes a principal face opposed to the magnetic field generating portion4and a principal face83athat is a back side with respect to the foregoing principal face. The mirror3is disposed on the principal face83aof the mirror arrangement portion83.

The actuator device2(mirror driving device1), as also shown inFIG. 3, includes a coil16disposed on the first movable portion81and a coil18disposed on the second movable portion82. The coil16is disposed on the principal face81aside of the first movable portion81. The coil18is disposed on the principal face82aside of the second movable portion82. In the present embodiment, the coil16is used as a conductor disposed on the first movable portion81and the coil18is used as a conductor disposed on the second movable portion82.

The coil16is wound in a spiral form of multiple turns when viewed from a direction orthogonal to the principal face81a. One end of the coil16is located outside the coil16and the other end of the coil16inside the coil16. One end of a lead conductor16bis electrically connected to an outside end of the coil16. One end of a lead conductor16ais electrically connected to an inside end of the coil16.

The lead conductors16a,16bare disposed mainly on one torsion bar portion10and extend from the first movable portion81to the support portion6. The other ends of the lead conductors16a,16bare electrically connected to respective electrodes17a,17bdisposed on the surface of the support portion6. The electrodes17a,17bare electrically connected to an unshown control circuit or the like. The lead conductor16ais grade-separated from the coil16so as to pass above the coil16.

The coil18is wound in a spiral form of multiple turns when viewed from a direction orthogonal to the principal face82a. One end of the coil18is located outside the coil18and the other end of the coil18inside the coil18. One end of a lead conductor18bis electrically connected to an outside end of the coil18. One end of a lead conductor18ais electrically connected to an inside end of the coil18.

The lead conductors18a,18bare disposed mainly on the torsion bar portions14, on the first movable portion81, and on one torsion bar portion10and extend from the second movable portion82to the other torsion bar portion10. The other ends of the lead conductors18a,18bare electrically connected to respective electrodes19a,19bdisposed on the surface of the support portion6. The electrodes19a,19bare electrically connected to the aforementioned unshown control circuit or the like. The lead conductors18a,18bare grade-separated from the coil16so as to pass above the coil16.

Now, let us describe a configuration of each torsion bar portion10, with reference toFIG. 4.FIG. 4is a drawing for illustrating the configuration of the torsion bar portion.

As shown inFIG. 4, each torsion bar portion10includes a plurality of straight sections10a(nine straight sections10a1to10a9in the present embodiment), a plurality of turnover sections10b(eight turnover sections10b1to108in the present embodiment), and a pair of connection sections10c,10d. The straight sections10a1to10a9extend in a first direction along the swing axis L of the torsion bar portion10and are juxtaposed in a second direction intersecting with the first direction. The turnover sections10b1to10b8are provided so as to extend in the second direction. In the present embodiment, the first direction and the second direction intersect at right angles.

The turnover sections10b1to10b8couple ends of two straight sections10a1to10a9adjacent in the second direction, out of the straight sections10a1to10a9. For example, one ends of the respective straight sections10a1and10a2are coupled to the turnover section10b1. In this way, the turnover sections10b1to10b8alternately couple the two ends of the straight sections10a2to10a8. In the present embodiment, the turnover sections10b1,10b2,10b7, and10b8are straight and the turnover sections10b3to106are curved.

The other end of the straight section10a1is coupled to one end of the connection section10d. The straight section10a1is one of the straight sections located outermost in the second direction out of the straight sections10a1to10a9. The other end of the connection section10dis coupled to the movable portion8at a connection point11b. Namely, the connection section10dis connected to the straight section10a1and to the movable portion8.

One end of the straight section10a9is coupled to one end of the connection section10c. The straight section10a9is the other of the straight sections located outermost in the second direction out of the straight sections10a1to10a9. The other end of the connection section10cis coupled to the support portion6at a connection point11a. Namely, the connection section10cis connected to the straight section10a9and to the support portion6.

The torsion bar portion10includes the straight sections10a1to10a9, the turnover sections10b1to10b8, and the connection sections10c,10d. This makes the torsion bar portion10of the meandering shape. The connection points11a,11bare located on a virtual line extending in a direction along the swing axis L. The virtual line passes through a central region in the second direction of the torsion bar portion10.

Next, let us describe the wiring20disposed on the torsion bar portion10, with reference toFIGS. 5 to 10.FIG. 5is a drawing for illustrating a cross-sectional configuration along the line V-V inFIG. 4.FIG. 6is a drawing for illustrating a cross-sectional configuration along the line VI-VI inFIG. 4.FIG. 7is a drawing for illustrating a cross-sectional configuration along the line VII-VII inFIG. 4.FIG. 8is a drawing for illustrating a cross-sectional configuration along the line inFIG. 4.FIG. 9is a drawing for illustrating a cross-sectional configuration along the line IX-IX inFIG. 4.FIG. 10is a drawing for illustrating a cross-sectional configuration along the line X-X inFIG. 4.

The wiring20constitutes sections disposed on the corresponding torsion bar portions10, of the lead conductors16a,16b,18a,18b. Namely, the lead conductors16a,16b,18a,18binclude the wiring20. The wiring20includes wiring sections21, wiring sections22, and wiring sections23. The wiring sections21are disposed on the turnover sections10b(10b1to10b8). The wiring sections22are disposed mainly on the straight sections10a(10a1to10a9). The wiring sections23are disposed on the connection sections10c,10d. The wiring sections23disposed on the connection section10care configured in the same configuration as the wiring sections23disposed on the connection section10d. For this reason, the cross-sectional configuration of the wiring sections23is shown for only the wiring sections23disposed on the connection section10d, while omitting the illustration of the cross-sectional configuration of the wiring sections23disposed on the connection section10c.

The wiring sections21, as also shown inFIGS. 7 to 9, are disposed so as to be embedded in grooves25aformed in the turnover sections10b. The wiring sections21are made of a first metal material including Cu and are formed by the damascene process. Namely, the wiring sections21include damascene wiring sections. The grooves25aare formed by etching the turnover sections10b. The thickness of the torsion bar portion10can be set, for example, approximately in the range of 20 μm to 60 μm. The depth of the grooves25acan be set, for example, approximately in the range of 5 μm to 15 μm.

The wiring sections22, as shown inFIGS. 5 and 6, are disposed on the straight sections10a. Specifically, the wiring sections22are disposed in an insulating layer26disposed on one principal face of the torsion bar portion10. The insulating layer26is configured so as to partly cover the wiring sections22. The insulating layer26is a thermally-oxidized film obtained by thermally oxidizing the torsion bar portion10. The insulating layer26is made, for example, of silicon oxide (SiO2). The thickness of the insulating layer can be set, for example, to approximately 0.5 μm.

The wiring sections22are made of a metal material more resistant to plastic deformation than Cu as the first metal material. The metal material constituting the wiring sections22is a metal material more resistant to plastic deformation than Cu; e.g., the metal material is Al or an alloy containing Al. Examples of the alloy containing Al include an Al—Si alloy, an Al—Cu alloy, an Al—Si—Cu alloy, and so on. A composition ratio of the Al—Si alloy can be, for example, Al 99% and Si 1%. A composition ratio of the Al—Cu alloy can be, for example, Al 99% and Cu 1%. A composition ratio of the Al—Si—Cu alloy can be, for example, Al 98%, Si 1%, and Cu 1%. When one of the foregoing metal materials is adopted as the metal material constituting the wiring sections22, the plastic deformation of the wiring sections22can be restrained quite well.

The wiring sections22include sections22alocated on the wiring sections21, as shown inFIGS. 7 to 9. The sections22aof the wiring sections22are disposed on the wiring sections21so as to cover openings of the grooves25a. The sections22aof the wiring sections22are connected to the wiring sections21.

As shown inFIG. 7, the wiring sections21disposed on the turnover sections10bare connected to the sections22aof the wiring sections22and the wiring sections23disposed on the connection section10dare connected to sections22bof the wiring sections22. In the wiring sections22disposed on the straight sections10a1, as shown inFIG. 8, the sections22aof the wiring sections22are connected to the wiring sections21. The wiring sections21are wiring formed by the damascene process. The wiring sections22are made, for example, of Al or the alloy containing Al.FIGS. 7 and 8show changeover regions between the wiring sections22disposed on the straight sections10aand the wiring sections21disposed on the turnover sections10b, in the wiring20.

The wiring sections23, as also shown inFIG. 10, are disposed so as to be embedded in grooves25bformed in the connection section10d(10c). The wiring sections23are made of the first metal material including Cu and formed by the damascene process. Namely, the wiring sections23also include damascene wiring sections. The grooves25bare formed by etching the connection section10d(10c). The depth of the grooves25bcan be set, for example, approximately in the range of 5 μm to 15 μm.

The wiring sections22include sections22blocated on the wiring sections23, as shown inFIG. 10. The sections22bof the wiring sections22are disposed on the wiring sections23so as to cover openings of the grooves25b. The sections22bof the wiring sections22are connected to the wiring sections23.

In the present embodiment, the magnetic field generating portion4generates a magnetic field with flow of an electric current through the coil16and the magnetic field thus generated exerts the Lorentz force in a predetermined direction on electrons flowing in the coil16. For this reason, the coil16is subject to the force in the predetermined direction. By controlling the direction and magnitude of the electric current flowing through the coil16, the first movable portion81swings around the swing axis of the torsion bar portions10. Namely, the first movable portion81rotates back and forth around the rotational axis of the torsion bar portions10. With flow of an electric current through the coil18, the magnetic field generating portion4generates a magnetic field and the magnetic field thus generated exerts the Lorentz force in a predetermined direction on electrons flowing in the coil18. For this reason, the coil18is subject to the force in the predetermined direction. By controlling the direction and magnitude of the electric current flowing through the coil18, the second movable portion82swings around the swing axis of the torsion bar portions14. Namely, the second movable portion82rotates back and forth around the rotational axis of the torsion bar portions14. Accordingly, the mirror arrangement portion83(mirror3) can be swung around each of the two orthogonal swing axes by controlling each of the directions, magnitudes, and so on of the electric currents through the coil16and through the coil18.

Incidentally, when the movable portion8(first movable portion81) swings around the swing axis of the torsion bar portions10, in each torsion bar portion10, high stress is exerted on the straight sections10aextending in the direction along the swing axis of the torsion bar portion10, as shown inFIG. 11.FIG. 11is a drawing for illustrating a state of the stress generated in the torsion bar portion10.FIG. 11shows the result of a simulation of the stress in the torsion bar portion10on the assumption that the support portion6is a substantially rectangular parallelepiped shape and that the movable portion8(first movable portion81) is a substantially rectangular flat plate shape. It proved that the high stress is exerted on regions indicated in black in the straight sections10aextending in the direction along the swing axis of the torsion bar portion10.

In the present embodiment, the wiring sections22disposed on the straight sections10aare made of Al or the alloy containing Al. For this reason, the wiring sections22are restrained from plastic deformation even in the case where the high stress is exerted on the straight sections10a. Therefore, it is feasible to prevent the wiring20disposed on the torsion bar portions10from inhibiting the swing motion of the movable portion8(first movable portion81).

In the present embodiment, the wiring sections21disposed on the turnover sections10bare the damascene wiring sections made of Cu. For this reason, it is feasible to achieve reduction in resistance of the wiring20disposed on the torsion bar portions10.

In the present embodiment, not only the wiring sections21but also the wiring sections23disposed on the connection sections10c,10dare the damascene wiring sections made of Cu. For this reason, even in the case where the wiring20includes the wiring sections23, increase in resistance of the wiring is suppressed. As a result, it is feasible to surely achieve reduction in resistance of the wiring20. The high stress is unlikely to be exerted on the connection sections10c,10d, as shown inFIG. 11. Therefore, even if the wiring sections23disposed on the connection sections10c,10dare the damascene wiring sections made of Cu, the possibility of inhibiting the swing motion of the movable portion8(first movable portion81) is also very low.

The wiring sections21,23are the damascene wiring sections as described above. For this reason, the corner edges located on the surface side of the turnover portions10band connection portions10c,10dmay be locally thinned so as to reduce the sectional area because of steps in their manufacturing process. The decrease in sectional area of the wiring sections21,23leads to increase in total resistance of the wiring20. However, since the wiring sections22include the sections22a,22bdisposed on the wiring sections21,23, the increase in resistance of the wiring20can be prevented even if the wiring sections21,23are thinned.

In the present embodiment, the aforementioned sections22a,22bare disposed so as to cover the openings of the grooves25a,25b. For this reason, Cu of the wiring sections21,23is less likely to diffuse into the insulating layer26. This suppresses occurrence of a short circuit between the metal materials constituting the wiring sections21,23(Cu in the present embodiment).

In the present embodiment, the connection points11a,11bare located on the virtual line extending in the first direction and passing through the central region in the second direction of the torsion bar portion10. The resonance frequency of the torsion bar portion10is determined by the width of the torsion bar portion10and the length in the first direction of the torsion bar portion10. A conceivable configuration to decrease the stress exerted on the straight sections10ais to increase the number of straight sections10a. The straight sections10aare not juxtaposed in the first direction along the swing axis L but juxtaposed in the second direction intersecting with the first direction. For this reason, there is no change in the length in the first direction of the torsion bar portion10, even with increase in the number of straight sections10ain the second direction. Therefore, it facilitates design of the torsion bar portion10for setting the resonance frequency of the torsion bar portion10to a desired value.

In the present embodiment, the resistance of the turnover sections10bis higher than that of the straight sections10a, because of their shape. For this reason, increase in the total resistance of the torsion bar portion10can be suppressed by disposing the wiring sections21formed by the damascene process, on the turnover sections10band disposing the wiring sections22on the straight sections10a.

In the present embodiment, the wiring sections22disposed on the straight sections10a(straight sections10a1to10a9) are made of Al or the alloy containing Al, but they do not have to be limited only to it. For example, as shown inFIGS. 12 and 13, the wiring sections22do not have to be disposed on all of the straight sections10a.FIG. 12is a drawing for illustrating a modification example of the configuration of the wiring, which corresponds to the cross-sectional configuration along the line V-V inFIG. 4.FIG. 13is a drawing for illustrating the modification example of the configuration of the wiring, which corresponds to the cross-sectional configuration along the line VI-VI inFIG. 4.

As shown inFIGS. 12 and 13, the wiring sections21formed by the damascene process may be disposed on the straight sections10a1,10a9located outermost in the second direction out of the straight sections10a. As shown inFIG. 11, the stress exerted on the straight sections10a1,10a9is lower than that exerted on the other straight sections (10a2to10a8). For this reason, even in the case where the wiring sections21are disposed on the straight sections10a1,10a9, the wiring sections21disposed on the straight sections10a1,10a9are less likely to undergo plastic deformation. When the wiring sections21are disposed on the straight sections10a1,10a9, the resistance of the wiring20can be further reduced.

The wiring sections21may also be disposed on the straight sections10a2,10a8. As shown inFIG. 11, the stress exerted on the straight sections10a1,10a2,10a8,10a9located outside in the second direction out of the straight sections10ais lower than that exerted on the straight sections10a3to10a7closer to the swing axis L. For this reason, even in the case where the wiring sections21are disposed on the straight sections10a1,10a2,10a8,10a9, the wiring sections21disposed on the straight sections10a1,10a2,10a8,10a9are less likely to undergo plastic deformation. When the wiring sections21are disposed on the straight sections10a1,10a2,10a8,10a9, the resistance of the wiring20can be further reduced.

The embodiment of the present invention has been described above, but it should be noted that the present invention is not always limited to the foregoing embodiment but can be modified.

In the aforementioned embodiment, the turnover sections10b1,10b2,10b7, and10b8were straight while the turnover sections10b3to106were curved, but they do not have to be limited to this. The turnover sections10ball may be straight, or, all may be curved. The turnover sections10bmay be an arbitrary combination of straight and curved shapes or may be different shapes.

In the foregoing embodiment, the torsion bar portion10was of the meandering shape consisting of the nine straight sections10a(10a1to10a9) and eight turnover sections10b(10b1to10b8), but the numbers of straight sections10aand turnover sections10bdo not have to be limited to them.

The above embodiment was described using the example where the mirror3and mirror arrangement portion83were of the circular shape, but the shape of the mirror3and mirror arrangement portion83may be, for example, a polygonal shape or an elliptical shape or the like.

The actuator device2may be an actuator device for driving a member except for the mirror3.

The above embodiment had the configuration in which only the torsion bar portions10were of the meandering shape and the wiring20was disposed on the torsion bar portions10, but the present invention does not have to be limited only to it. For example, the torsion bar portions10,14may be of the meandering shape and the wiring20may be disposed thereon. Only the torsion bar portions14may be of the meandering shape and the wiring20may be disposed on the torsion bar portions14.

More preferably, the torsion bar portions10are of the meandering shape and the wiring20is disposed on the torsion bar portions10. The stress on the torsion bar portions14is stress exerted during the swing motion of the second movable portion82. The stress on the torsion bar portions10is stress exerted during the swing motion of the first movable portion81and the second movable portion82. Namely, the stress on the torsion bar portions14is lower than that on the torsion bar portions10. For this reason, the torsion bar portions14are less likely to pose the problem due to the stress than the torsion bar portions10. Therefore, the structure of the torsion bar portions14can be the simple configuration, which can increase a yield in manufacture of the actuator device2.

In the present embodiment, the movable portion8is configured so as to be driven in the two axis directions, the swing axis of the torsion bar portions10and the swing axis of the torsion bar portions14, but the present invention is not limited only to it. For example, the actuator device2may be configured so as to be driven by one coil disposed on a movable portion. The actuator device2may be preferably configured so that the lead conductors are disposed on the pair of respective torsion bar portions. Since the lead conductors are disposed on the torsion bar portions, whether the torsion bar portions are damaged can be known by the presence or absence of an electric current flowing in the lead conductors. The actuator device2may be configured by adopting a configuration in which the operation of the actuator device is suspended with detection of the damage.

In the case where the lead conductors are disposed on the pair of respective torsion bar portions, the number of grooves formed in the torsion bar portions is smaller than in the case where the lead conductors are disposed on only one torsion bar portion of the pair of torsion bar portions. For this reason, the stress on the torsion bar portions can be reduced. Furthermore, since the wiring disposed on each torsion bar portion is one wire, it can prevent a short circuit between wires.

In the present embodiment, the swing motion (drive) of the movable portion8is implemented by electromagnetic force, but the present invention does not have to be limited only to it. For example, the swing motion (drive) of the movable portion8may be implemented by a piezoelectric device. In this case, the wiring20is used as wiring for applying a voltage to the piezoelectric device.

REFERENCE SIGNS LIST