JP2007233192A - Actuator - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an actuator which is miniaturized and can be stably driven with improved freedom of design. <P>SOLUTION: The actuator 1 has a driving means which turns first mass parts 21 and 22 while torsionally deforming a first elastic connection part 25, accordingly turns a second mass part 23 while torsionally deforming a second elastic connection part 26. The actuator 1 also has a behavior detection means which detects the behavior of the second mass part 23, the behavior detection means is provided with a transmission type optical sensor 10 which detects the passing of the side face of the second mass part 23 and detects the behavior of the second mass part 23 on the basis of the detected result of the optical sensor 10. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an actuator.

As an optical scanner for performing drawing by optical scanning with a laser printer or the like, an optical scanner using an actuator composed of a torsional vibrator is known (for example, see Patent Document 1).
For example, the actuator (optical scanner) according to Patent Document 1 is configured by a torsional vibrator having a one-degree-of-freedom vibration system. That is, such an actuator is configured to support the mass portion so as to be rotatable with respect to the support portion via a torsion spring.

A light reflecting part is provided on the mass part, and the light reflected by the light reflecting part is scanned by rotating the mass part while twisting and deforming the torsion spring. Thereby, drawing can be performed by optical scanning.
An actuator composed of such a torsional vibrator can be driven stably when driven at the resonance frequency.

Conventionally, in such an actuator, generally, a reflective optical sensor is opposed to the plate surface of the mass portion, and the behavior of the mass portion is detected based on the detection result of the optical sensor. Based on the detection result, the behavior (frequency, amplitude, etc.) of the mass part can be controlled to be a desired one and can be operated stably.
However, in such an actuator, since the detection target of the optical sensor is the plate surface of the mass part, the area for receiving the light from the optical sensor is separately from the area for optical scanning. Since it is necessary to provide in this, a mass part will enlarge. In addition, since the moment of inertia of the mass portion increases as the mass portion becomes larger, the degree of freedom in designing the actuator is reduced.

K.E.Petersen: “Silicon Torsional Scanning Mirror”, IBM J. Res. Development., Vol. 24 (1980), p. 631

  An object of the present invention is to provide an actuator that can be stably driven while reducing the size and improving the degree of freedom in design.

Such an object is achieved by the present invention described below.
The actuator of the present invention includes a plate-like mass part,
A support part for supporting the mass part;
An elastic coupling part that couples the mass part and the support part so that the mass part is rotatable with respect to the support part;
Drive means for rotationally driving the mass part,
An actuator for rotating the mass part while the driving means twists and deforms the elastic connecting part;
Having a behavior detecting means for detecting the behavior of the mass part;
The behavior detection means includes a reflective or transmissive optical sensor that detects passage of a side surface of the mass unit, and is configured to detect the behavior of the mass unit based on a detection result of the optical sensor. It is characterized by being.

  Thus, the behavior of the mass part can be detected without separately providing a region for behavior detection on the plate surface of the mass part, and based on this, the mass part can be driven stably. In particular, since it is not necessary to provide a separate area for detecting the behavior on the plate of the mass part, the mass part can be downsized, and the actuator can be downsized, and the degree of freedom in designing the actuator can be improved. Can do. Moreover, since an optical sensor is used, the behavior can be detected in a non-contact manner with respect to the mass part, and the rotation of the mass part is not hindered.

The actuator of the present invention includes a first mass part,
A support part for supporting the first mass part;
A first elastic connecting portion that connects the first mass portion and the support portion so that the first mass portion is rotatable with respect to the support portion;
A second mass part in the form of a plate;
A second elastic connecting portion for connecting the second mass portion and the first mass portion so that the second mass portion is rotatable with respect to the first mass portion;
Drive means for rotationally driving the first mass part;
The drive means rotates the first mass portion while twisting and deforming the first elastic connecting portion, and accordingly, the second mass portion is deformed while twisting and deforming the second elastic connection portion. An actuator to rotate,
Having a behavior detecting means for detecting the behavior of the second mass part;
The behavior detection unit includes a reflective or transmissive optical sensor that detects passage of a side surface of the first mass unit or the second mass unit, and based on a detection result of the optical sensor, It is comprised so that the behavior of the mass part of may be detected.

  Accordingly, the behavior of the second mass part is detected without separately providing a region for behavior detection on the plate surface of the second mass part, and based on this, the second mass part is stably driven. be able to. In particular, since it is not necessary to separately provide a region for detecting the behavior on the plate surface of the second mass portion, the second mass portion can be downsized, and the actuator can be downsized. The degree of freedom can be improved. Further, since the optical sensor is used, the behavior can be detected in a non-contact manner with respect to the first mass unit and the second mass unit, and the rotation of the first mass unit and the second mass unit is hindered. There is nothing.

In the actuator of the present invention, the behavior detecting means is configured to detect at least one of the vibration amplitude, the vibration frequency, and the displacement amount of the second mass portion as the behavior of the second mass portion. It is preferable that
Thereby, based on the detection result of the behavior detection means, the amplitude, vibration frequency, and phase of the second mass part can be set as desired, and the second mass part can be driven more reliably and stably.

In the actuator according to the aspect of the invention, the optical sensor includes a light emitting unit that emits light toward a rotation space from a side of the first mass unit or the second mass unit, and light emitted from the light emitting unit. It is preferable that the behavior detecting unit is configured to detect the behavior of the second mass unit based on the intensity of light received by the light receiving unit.
Thereby, the light-emitting part and the light-receiving part constitute a transmissive or reflective optical sensor, and the behavior of the second mass part can be detected more accurately.

In the actuator according to the aspect of the invention, it is preferable that the light emitting unit emits light in a direction along a rotation center axis of the first mass unit or the second mass unit.
Thereby, it is possible to prevent the actuator from increasing in size in a direction perpendicular to the rotation center axis of the second mass unit.
In the actuator according to the aspect of the invention, the light emitting unit and the light receiving unit are disposed with respect to each other through the rotation space, and the first mass unit or the second mass unit as a target of these is rotated with a predetermined rotation. Only when it becomes a corner, the light from the light emitting unit to the light receiving unit is blocked by the first mass unit or the second mass unit, and based on the presence or absence of light reception by the light receiving unit, the second It is preferable to detect the behavior of the mass part.
Thereby, a light transmission part and a light-receiving part constitute a transmissive optical sensor, and the behavior of the second mass part can be detected more accurately.

In the actuator according to the aspect of the invention, the light emitting unit and the light receiving unit are both disposed on one side with respect to the rotation space, and the first mass unit or the second mass unit as a target of these is predetermined. The light from the light emitting part is reflected by the side surface of the first mass part or the second mass part and is received by the light receiving part only when the rotation angle becomes, and the light receiving part receives the light. It is preferable to detect the behavior of the second mass part based on the presence or absence of the.
Thereby, a reflective optical sensor is comprised with a light emission part and a light-receiving part, and the behavior of a 2nd mass part can be detected more correctly.

In the actuator of the present invention, the light emitting unit and the light receiving unit are arranged to be shifted in the plate thickness direction with respect to the first mass unit or the second mass unit in the non-driven state as a target. Is preferred.
As a result, the optical sensor detects the passage of a part of the first mass part and / or the second mass part that is causing simple vibrations at a certain distance from the rotation center axis, so that the passage time is reached. Based on this, it is possible to know the rotational direction and rotational speed of the first mass part and / or the second mass part. That is, the behavior (phase, frequency, absolute displacement) of the first mass part and / or the second mass part is directly (without estimating from the location where the single vibration is caused) from the detection result of the optical sensor. Can be sought.

In the actuator according to the aspect of the invention, it is preferable that the light emitting unit includes a light emitting element and an optical waveguide, and the light emitting element is configured to irradiate the rotation space with light through the optical waveguide.
Thereby, even if the 2nd mass part is thin, the diameter of the light from a light emission part can be made below into the thickness of the 2nd mass part comparatively easily. As a result, the degree of freedom in designing the actuator can be further improved, and the detection accuracy of the optical sensor can be improved.

In the actuator according to the aspect of the invention, it is preferable that the light receiving unit includes a light receiving element and an optical waveguide, and the light receiving element is configured to receive light through the optical waveguide. .
As a result, even if the second mass part is thin, the diameter of the light receiving part can be made equal to or less than the thickness of the second mass part, relatively easily. As a result, the degree of freedom in designing the actuator can be further improved, and the detection accuracy of the optical sensor can be improved.

In the actuator according to the aspect of the invention, it is preferable that the second mass unit has a light reflecting unit.
Thereby, the present invention can be applied to optical devices such as an optical scanner, an optical switch, and an optical attenuator.
The actuator according to the aspect of the invention preferably includes a control unit that controls the driving of the driving unit based on the behavior detected by the behavior detecting unit.
Thereby, the 1st mass part and / or the 2nd mass part can be driven stably.

DESCRIPTION OF EXEMPLARY EMBODIMENTS Hereinafter, preferred embodiments of an actuator of the invention will be described with reference to the accompanying drawings.
<First Embodiment>
First, a first embodiment of the actuator of the present invention will be described.
1 is a plan view showing a first embodiment of the actuator of the present invention, FIG. 2 is a cross-sectional view taken along line AA in FIG. 1, FIG. 3 is a cross-sectional view taken along line BB in FIG. 1 is a plan view showing the arrangement of electrodes of the actuator shown in FIG. 1, FIG. 5 is a block diagram showing a control system of the actuator shown in FIG. 1, and FIG. 6 is an example of the drive voltage of the actuator shown in FIG. FIG. 7 is a graph showing the relationship between the frequency of the applied AC voltage and the amplitude of the first and second mass parts, and FIG. 8 is provided in the actuator shown in FIG. FIG. 9 is a perspective view for explaining the optical sensor, and FIG. 9 is a view for explaining the operation of the optical sensor provided in the actuator shown in FIG. In the following, for convenience of explanation, the front side of the page in FIGS. 1 and 4 is referred to as “up”, the back side of the page is referred to as “down”, the right side is referred to as “right”, and the left side is referred to as “left”. The upper side is “upper”, the lower side is “lower”, the right side is “right”, the left side is “left”, the upper side in FIG. 3 is “upper”, the lower side is “lower”, and the front side of the page is “right” "The back side of the page is called" left ".

As shown in FIG. 1, the actuator 1 has a base 2 having a two-degree-of-freedom vibration system. A counter substrate 3 is bonded to the lower surface of the base 2 via a bonding layer 4. Is provided with an optical sensor 10 for detecting the behavior (driving state) of the two-degree-of-freedom vibration system.
The base 2 includes a pair of first mass units (drive units) 21 and 22 and a second mass unit (movable) provided with a light reflecting unit 231 on an upper surface (a surface opposite to a counter substrate 3 described later). Part) 23 and a support part 24 for supporting them.
Specifically, the base body 2 is provided with a first mass portion 21 on one end side (left side in FIGS. 1 and 2) around the second mass portion 23 and on the other end side (FIG. 1 and FIG. 2). The first mass unit 22 is provided on the right side in FIG.

In the present embodiment, the first mass parts 21 and 22 have substantially the same shape and the same dimensions as each other, and are provided substantially symmetrically via the second mass part 23.
Further, a light reflecting portion 231 is provided on the second mass portion 23. Thereby, the actuator 1 can be applied to optical devices such as an optical scanner, an optical switch, and an optical attenuator.
Further, as shown in FIGS. 1 and 2, the base body 2 includes a pair of first elastic connecting portions 25 and 25 that connect the first mass portions 21 and 22 and the support portion 24, and a first mass portion. 21 and 22 and the second mass part 23 are provided with a pair of second elastic connection parts 26 and 26.

The first elastic connecting portions 25, 25 and the second elastic connecting portions 26, 26 are provided coaxially, and the first mass portion 21 is set with the rotation central axis (rotating shaft) 27 as a center axis. , 22 can rotate with respect to the support portion 24, and the second mass portion 23 can rotate with respect to the first mass portions 21, 22.
As described above, the base 2 includes the first vibration system including the first mass portions 21 and 22 and the first elastic coupling portions 25 and 25, the second mass portion 23 and the second elastic coupling portion 26. , 26 and a second vibration system composed of a two-degree-of-freedom vibration system.

In the present embodiment, such a two-degree-of-freedom vibration system is formed thinner than the entire thickness of the base 2 and is positioned above the base 2 in the vertical direction in FIG. In other words, the base 2 is formed with a portion thinner than the entire thickness of the base 2 (hereinafter referred to as a thin portion), and the first mass portion is formed by forming a deformed hole in the thin portion. 21 and 22, the 2nd mass part 23, the 1st elastic connection parts 25 and 25, and the 2nd elastic connection parts 26 and 26 are formed.
Moreover, in this embodiment, when the upper surface of the said thin part is located on the same surface as the upper surface of the support part 24, it is for the rotation of each mass part 21, 22, 23 below the said thin part. A space (concave portion) 28 is formed.

Such a base body 2 is made of, for example, silicon as a main material, and includes first mass parts 21, 22, a second mass part 23, a support part 24, a first elastic coupling part 25, 25 and the second elastic connecting portions 26, 26 are integrally formed.
Note that the base body 2 includes a first mass portion 21, 22, a second mass portion 23, a support portion 24, a first elastic coupling portion 25, 25, and a laminated structure substrate such as an SOI substrate. The 2nd elastic connection part 26 and 26 may be formed.

The counter substrate 3 is bonded to the lower surface of the base 2 via the bonding layer 4.
The counter substrate 3 is made of, for example, silicon or glass as a main material.
As shown in FIGS. 2 and 4, an opening 31 is formed in the portion corresponding to the second mass portion 23 on the upper surface of the counter substrate 3.
The opening 31 constitutes an escape portion that prevents contact with the counter substrate 3 when the second mass portion 23 rotates (vibrates). By providing the opening (escape portion) 31, the deflection angle (amplitude) of the second mass portion 23 can be set larger while preventing the actuator 1 from being enlarged. In the actuator 1, when the counter substrate 3 is made of silicon as a main material, the above-described relief portion such as the opening can be easily and high compared to the case where the counter substrate is made of a glass material or the like. It can be formed with high accuracy (high aspect ratio).

  Note that the relief portion does not necessarily have to be opened (opened) on the lower surface (the surface opposite to the second mass portion 23) of the counter substrate 3 as long as the above-described effect can be sufficiently exerted. That is, the escape portion can also be configured by a recess formed on the upper surface of the counter substrate 3. Further, when the depth of the space 28 is larger than the deflection angle (amplitude) of the second mass portion 23, the escape portion need not be provided.

  Further, as shown in FIG. 4, a pair of electrodes 32 is provided on the upper surface (surface on the base 2 side) of the counter substrate 3 at a portion corresponding to the first mass portion 21 via a bonding layer 4 described later. A pair of electrodes 32 is provided on the portion corresponding to the first mass portion 22 via a bonding layer 4 to be described later. It is provided so as to be almost symmetrical about the center. That is, in this embodiment, two pairs (a total of four) of the pair of electrodes 32 are provided.

The first mass parts 21 and 22 and each electrode 32 are connected to an energization circuit 13 to be described later, and an alternating voltage (drive voltage) is applied between the first mass parts 21 and 22 and each electrode 32. It is configured to be able to. That is, the first mass parts 21 and 22 and the respective electrodes 32 constitute a driving means for driving the second mass part 23 (more specifically, the first mass parts 21 and 22).
In addition, the 1st mass parts 21 and 22 are each provided with the insulating film (not shown) in the surface facing each electrode 32. As shown in FIG. Thereby, it is prevented suitably that the short circuit between the 1st mass parts 21 and 22 and each electrode 32 occurs.

  The bonding layer 4 has a function of bonding the base 2 and the counter substrate 3 together. Therefore, the constituent material of the bonding layer 4 is not particularly limited as long as it can be bonded. However, when each of the base 2 and the counter substrate 3 is composed mainly of silicon, Na ions or K It is preferable to use a glass containing mobile ions such as alkali metal ions such as ions. As a result, the base 2 and the counter substrate 3 both made of silicon as the main material can be anodically bonded via the bonding layer 4.

In the present embodiment, the above-described electrode 32 is provided on the upper surface of the bonding layer 4. Thereby, the gap between the electrode 32 and the 1st mass parts 21 and 22 can be adjusted. Moreover, the insulation between the electrode 32 and the opposing board | substrate 3 is securable by comprising the joining layer 4 with the material which has insulation.
In addition, a transmissive optical sensor 10 that detects the passage of the side surface of the second mass portion 23 described above is provided on the upper surface of the substrate 2 described above.

The optical sensor 10 includes a light emitting unit 11 that emits light toward the rotation space of the second mass unit 23 and a light receiving unit 12 that receives light from the light emitting unit 11 through the rotation space.
The light emitting unit 11 emits light from the side of the second mass unit 23 (right side in FIG. 1) toward the rotation space, and includes an optical waveguide 111 and a light emitting element 112. .
The optical waveguide 111 has a linear core portion 113 that is an optical transmission path, and a clad portion 114 that covers the outer periphery of the core portion 113.

The core part 113 has a refractive index higher than that of the cladding part 114, and constitutes an optical transmission path.
The clad part 114 covering the outer periphery of the core part 113 is bonded onto the support part 24 of the base 2 described above, and supports the core part 113.
Further, of the both end surfaces of the linear core portion 113, one end surface 115 faces the rotation space of the second mass portion 23, and the other end surface 116 is connected to the light emitting element 112. Thereby, the light of the light emitting element 112 can be irradiated to the rotation space of the second mass portion 23 through the core portion 113.
The light emitting element 112 is not particularly limited, and various light emitting elements can be used. For example, a light emitting diode, a light emitting FET, an EL element, or the like can be preferably used.

On the other hand, the light receiving unit 12 receives light from the light emitting unit 11 described above, and includes an optical waveguide 121 and a light receiving element 122.
Similar to the optical waveguide 111 described above, the optical waveguide 121 includes a linear core portion 123 that is an optical transmission path, and a clad portion 124 that covers the outer periphery of the core portion 123.
The core portion 123 has a refractive index higher than that of the cladding portion 124, and constitutes an optical transmission path.

The clad portion 124 that covers the outer periphery of the core portion 123 is joined to the support portion 24 of the base 2 described above, and supports the core portion 123.
Further, of the both end faces of the linear core portion 123, one end face 125 faces the rotation space of the second mass part 23, and the other end face 126 is connected to the light receiving element 122. Thereby, the light that has passed through the rotation space of the second mass part 23 from the light emitting element 112 can be received by the light receiving element 122 through the core part 123.

The light receiving element 122 is not particularly limited as long as it can receive the light of the light emitting element 112. Photoelectric tube, photomultiplier tube, photoconductive cell, photodiode, phototransistor, avalanche photodiode, pyroelectric type Various light receiving elements such as an infrared element can be used. For example, a photoelectric tube, a photomultiplier tube, a photodiode, or the like can be preferably used.
Such an optical sensor 10 is connected to a control circuit 14 that controls driving of the driving means described above (specifically, driving of the energization circuit 13). Thereby, the drive of the actuator 1 can be controlled based on the detection result of the optical sensor 10.

Hereinafter, the control system of the actuator 1 will be described in detail with reference to FIG.
As shown in FIG. 5, in the actuator 1 of the present embodiment, the electrode 32 described above is connected to the energization circuit 13. The energization circuit 13 selectively applies a voltage (generates a potential difference) between each electrode 32 and the first mass parts 21 and 22.
The energization circuit 13 is connected to a control circuit 14 having a function of controlling driving of the energization circuit 13.

The control circuit 14 is connected to the light receiving element 122 (light receiving unit 12) of the optical sensor 10 described above, and the control circuit 14 controls the driving of the energization circuit 13 based on the detection result of the light receiving element 122. It is like that.
That is, the control circuit 14 detects the behavior of the second mass unit 23 based on the intensity of the light received by the light receiving unit 12, and drives the driving means (drives the energization circuit 13) based on the detection result. ).

In other words, the control circuit 14 and the optical sensor 10 constitute a behavior detection unit that detects the behavior of the second mass unit 23, and the control circuit 14 is based on the behavior detected by the behavior detection unit. Control means for controlling the drive of the drive means is configured. Thereby, the 1st mass parts 21 and 22 and / or the 2nd mass part 23 can be driven stably.
More specifically, the control circuit 14 includes a CPU 141, an AD conversion circuit 142, a ROM 143, and a RAM 144 as shown in FIG.
The CPU 141 is connected to the energization circuit 13 and is connected to the light receiving element 122 via the AD conversion circuit 142.

The AD conversion circuit 142 converts the output of the light receiving element 122 from analog to digital.
The ROM 143 stores a program for calculating the behavior of the second mass unit 23 based on the detected intensity of the light receiving element 122, a program for controlling the energization circuit 13 based on the calculated behavior, and the like. .

The RAM 144 has a function of storing values calculated by programs.
The CPU 141 detects the behavior of the second mass unit 23 based on the detection intensity digitized by the AD conversion circuit 142 in accordance with a program stored in the ROM 143. In addition, the CPU 141 controls the energization circuit 13 according to the program stored in the ROM 143 so that the behavior of the second mass unit 23 is desired based on the detected behavior.

As described above, in the actuator 1 of the present embodiment, the behavior of the second mass unit 23 is detected based on the detection result of the transmission optical sensor 10 that detects the passage of the side surface of the second mass unit 23. It is configured.
Accordingly, the behavior of the second mass unit 23 is detected without separately providing a region for detecting the behavior on the plate surface of the second mass unit 23, and based on this, the second mass unit 23 is stabilized. Can be driven. In particular, since it is not necessary to separately provide a region for detecting the behavior on the plate surface of the second mass portion 23, the second mass portion 23 can be downsized, and the actuator 1 can be downsized. The degree of freedom in designing the actuator 1 can be improved.

The actuator 1 having the above configuration is driven as follows.
That is, for example, a sine wave (AC voltage) or the like is applied between the first mass parts 21 and 22 and each electrode 32. Specifically, for example, the first mass parts 21 and 22 are grounded, and a voltage having a waveform as shown in FIG. 6A is applied to the upper two electrodes 32 in FIG. A voltage having a waveform as shown in FIG. 6B is applied to the two middle and lower electrodes 32. Then, an electrostatic force (Coulomb force) is generated between the first mass parts 21 and 22 and each electrode 32.

Due to this electrostatic force, the force that the first mass portions 21 and 22 are attracted toward the electrodes 32 changes depending on the phase of the sine wave, and the rotation center shaft 27 (the first elastic coupling portion 25) serves as an axis. Then, it vibrates (rotates) so as to be inclined with respect to the plate surface of the substrate 2 (paper surface in FIG. 1).
The second mass portion 23 connected via the second elastic connecting portion 26 with the vibration (drive) of the first mass portions 21 and 22 is also connected to the rotation center shaft 27 (second The elastic coupling portion 26) is vibrated (rotated) so as to be inclined with respect to the plate surface of the base 2 (the paper surface in FIG. 1).
Therefore, as the second mass unit 23 rotates, the light reflecting unit 231 also rotates, and the light irradiated on the light reflecting unit 231 can be scanned.

Here, in the actuator 1, as described above, the opening 31 is formed in the portion of the counter substrate 3 corresponding to the second mass portion 23, and the space 28 is formed on the lower surface of the base 2 in FIG. And the first mass portions 21 and 22 are provided so as to be positioned in the space (recessed portion) 28 in plan view.
With such a configuration, a large space is secured as a space where the second mass portion 23 can vibrate and a space where the first mass portions 21 and 22 can vibrate. Accordingly, by setting the masses of the first mass parts 21 and 22 to be relatively small, the first mass parts 21 and 22 are vibrated with a large deflection angle, or the second mass part 23 is further resonant. Thus, even when the vibrator vibrates with a large deflection angle, it is possible to suitably prevent each of the mass portions 21, 22, 23 (two-degree-of-freedom vibration system) from contacting the counter substrate 3.
For this reason, when such an actuator 1 is applied to, for example, an optical scanner, scanning with higher resolution can be performed.

Here, the length of a direction substantially perpendicular to the rotational axis of the first mass portion 21 (longitudinal direction) (the distance between the rotational axis and the edge 211) and L _1, the substantially perpendicular from the rotation center axis of the mass portion 22 to the length of the (longitudinal) (distance between the rotational axis and the edge 221) and L _2, second mass when the length of the 23 central axis of rotation of the direction substantially perpendicular thereto (the distance between the rotational axis and the end portion 232) and the L _3, in the present embodiment, the first mass portion 21 , 22 are provided independently of each other, the first mass parts 21, 22 and the second mass part 23 do not interfere with each other, and the size (length L _{3) of} the second mass part 23 is not affected. ), L ₁ and L ₂ can be made small. Thereby, the rotation angle (swing angle) of the 1st mass parts 21 and 22 can be enlarged, and the rotation angle of the 2nd mass part 23 can be enlarged.
In addition, by reducing L ₁ and L ₂ , the distance between the first mass parts 21 and 22 and each electrode 32 can be reduced, thereby increasing the electrostatic force and the first mass. The alternating voltage applied to the parts 21 and 22 and each electrode 32 can be reduced.

Here, the dimension of the first mass portions 21 and 22 and the second mass 23 is set _{respectively,} L 1 _{<L 3} and to satisfy _L 2 _{<L 3} becomes relevant. Thus, it is possible to further reduce the L ₁ and L _2, it is possible to the rotation angle of the first mass portions 21 and 22 to further increase, to further increase the rotation angle of the second mass 23 it can.
In this case, it is preferable that the maximum rotation angle of the second mass unit 23 is configured to be 20 ° or more.
In addition, by reducing L ₁ and L ₂ in this way, the distance between the first mass parts 21 and 22 and the respective electrodes 32 can be further reduced, and the first mass parts 21 and 22 can be reduced. The AC voltage applied to each electrode 32 can be further reduced.

By these, the low voltage drive of the 1st mass parts 21 and 22 and the vibration (rotation) in the large rotation angle of the 2nd mass part 23 are realizable.
For this reason, when such an actuator 1 is applied to, for example, an optical scanner used in an apparatus such as a laser printer or a scanning confocal laser microscope, the apparatus can be more easily downsized.
As described above, in the present embodiment, L ₁ and L ₂ are set to be substantially equal, but it goes without saying that L ₁ and L ₂ may be different.

By the way, in such a vibration system (two-degree-of-freedom vibration system) composed of the mass parts 21, 22, and 23, the amplitude (deflection angle) of the first mass part 21, 22 and the second mass part 23 is applied. A frequency characteristic as shown in FIG. 7 exists between the frequency of the AC voltage.
That is, the vibration system includes two resonance frequencies fm ₁ [kHz] and fm ₃ [kHz] (however, fm) in which the amplitude of the first mass parts 21 and 22 and the amplitude of the second mass part 23 are increased. ₁ <fm ₃ ) and one anti-resonance frequency fm ₂ [kHz] at which the amplitude of the first mass parts 21 and 22 is substantially zero.

In this vibration system, the frequency F of the AC voltage applied between the first mass parts 21 and 22 and the electrode 32 is set so as to be approximately equal to the lower one of the two resonance frequencies, that is, fm _1. Is preferred. Thereby, the deflection angle (rotation angle) of the second mass unit 23 can be increased while suppressing the amplitude of the first mass units 21 and 22.
In this specification, F [kHz] and fm ₁ [kHz] being substantially equal means that the condition of (fm ₁ −1) ≦ F ≦ (fm ₁ +1) is satisfied.

The average thicknesses of the first mass parts 21 and 22 are each preferably 1 to 1500 μm, and more preferably 10 to 300 μm.
The average thickness of the second mass part 23 is preferably 1 to 1500 μm, and more preferably 10 to 300 μm.
The spring constant _{k 1} of the first elastic connecting portions 25, 1 × and even preferably at ^{10 -4 ~1 × 10 4 Nm /} rad, 1 × ¹⁰ to a -2 ~1 × ¹⁰ 3 Nm / rad More preferably, it is 1 × 10 ⁻¹ to 1 × 10 ² Nm / rad. Thereby, the rotation angle (swing angle) of the second mass unit 23 can be further increased.

On the other hand, the spring constant k ₂ of the second elastic coupling portion 26 is preferably 1 × 10 ⁻⁴ to 1 × 10 ⁴ Nm / rad, and preferably 1 × 10 ⁻² to 1 × 10 ³ Nm / rad. Is more preferably 1 × 10 ⁻¹ to 1 × 10 ² Nm / rad. Thereby, the deflection angle of the 2nd mass part 23 can be enlarged more, suppressing the deflection angle of the 1st mass parts 21 and 22. FIG.
Further, the spring constant _{k 1} of the first elastic connecting portions 25 and _{k 2} the spring constant of the second elastic connecting portions _26, preferably satisfies the k 1> _{k 2} the relationship. Thereby, it is possible to increase the rotation angle (deflection angle) of the second mass unit 23 while suppressing the deflection angle of the first mass units 21 and 22.

Furthermore, the moment of inertia of the first mass portions 21 and 22 and _{J 1,} when the moment of inertia of the second mass 23 has a _{J 2,} and _{J 1} and _{J 2,} the _{J 1} ≦ _{J 2} the relationship It is preferable to satisfy, and it is more preferable to satisfy the relationship of J ₁ <J ₂ . Thereby, it is possible to increase the rotation angle (deflection angle) of the second mass unit 23 while suppressing the deflection angle of the first mass units 21 and 22.

Incidentally, the natural frequency ω ₁ of the first vibration system composed of the first mass parts 21 and 22 and the first elastic coupling parts 25 and 25 is equal to the inertia moment J _{1 of} the first mass parts 21 and 22. And ω ₁ = (k ₁ / J ₁ ) ^1/2 by the spring constant k _{1 of} the first elastic coupling part 25. On the other hand, the natural frequency ω ₂ of the second vibration system composed of the second mass portion 23 and the second elastic coupling portions 26 and 26 is equal to the moment of inertia J _{2 of} the second mass portion 23 and the second According to the spring constant k ₂ of the elastic coupling part 26, ω ₂ = (k ₂ / J ₂ ) ^1/2 is given.
It is preferable that the natural frequency ω ₁ of the first vibration system and the natural frequency ω ₂ of the second vibration system obtained in this way satisfy the relationship ω ₁ > ω ₂ . Thereby, it is possible to increase the rotation angle (deflection angle) of the second mass unit 23 while suppressing the deflection angle of the first mass units 21 and 22.

Here, based on FIG. 8, FIG. 9, an example of the detection of the behavior of the 2nd mass part 23 is demonstrated more concretely.
When the second mass portion 23 is in the non-driven state (home position), as shown in FIGS. 8 and 9A, the one end surface 115 of the core portion 113 of the light emitting portion 11 and the core portion of the light receiving portion 12. It is located below each of the one end surfaces 125 of 123. That is, the light emitting unit 11 and the light receiving unit 12 are arranged so as to be shifted in the plate thickness direction with respect to the second mass unit 23 in a non-driven state as a target (detection target of the optical sensor 10). As a result, the optical sensor 10 detects the passage of a part of the second mass unit 23 that is causing simple vibrations at a certain distance from the rotation center axis 27, and based on the passage time, the second The rotation direction and rotation speed of the mass part 23 can be known. That is, the behavior (phase, frequency, absolute displacement) of the second mass unit 23 is directly estimated from the detection result of the optical sensor 10 (without estimating from the location where the second mass unit 23 causes a single vibration). ) You can ask.

Then, when the actuator 1 is in a driving state, the second mass unit 23 temporarily blocks the light from the light emitting unit 11 to the light receiving unit 12 as shown in FIG. ), The position reaches the position where the deflection angle is maximized.
Thereafter, as shown in FIG. 9D, the second mass unit 23 temporarily blocks light from the light emitting unit 11 to the light receiving unit 12 again, as shown in FIG. Lead to position.

As described above, since the second mass unit 23 vibrates singly and the optical sensor 10 is fixedly arranged, the timing and time length at which the light from the light emitting unit 11 to the light receiving unit 12 is blocked are measured. Thus, the behavior of the second mass unit 23 can be detected.
Further, in the present embodiment, as described above, the light emitting unit 11 and the light receiving unit 12 are disposed through the rotation space of the second mass unit 23, and these objects (detection objects of the optical sensor 10). The light from the light emitting unit 11 to the light receiving unit 12 is blocked by the second mass unit 23 only when the second mass unit 23 has a predetermined rotation angle. Based on this, the behavior of the second mass unit 23 is detected. Thereby, the light-emitting part 11 and the light-receiving part 12 constitute a transmissive optical sensor 10, and the behavior of the second mass part 23 can be detected more accurately.

Moreover, since the light emission part 11 irradiates light in the direction along the rotation center axis | shaft 27 of the 1st mass part 21 and 22 or the 2nd mass part 23, the rotation center axis | shaft of the 2nd mass part 23 is carried out. It is possible to prevent the actuator 1 from increasing in size in a direction perpendicular to 27.
In addition, since the light emitting unit 11 and the light receiving unit 12 are arranged so as to be shifted in the plate thickness direction with respect to the target non-driven second mass unit 23, this causes a single vibration. When the optical sensor 10 detects the passage of a part of the second mass part 23 at a certain distance from the pivot center axis 27, based on the passage time, the rotation direction and rotation of the second mass part 23 are detected. You can know the speed of movement. That is, the behavior (phase, frequency, absolute displacement) of the second mass unit 23 is directly estimated from the detection result of the optical sensor 10 (without estimating from the location where the second mass unit 23 causes a single vibration). ) You can ask.

Further, since the light emitting element 112 is configured to irradiate light to the rotation space of the second mass portion 23 via the optical waveguide 111, it is relatively easy even if the second mass portion 23 is thin. The diameter of the light from the light emitting unit 11 can be made equal to or less than the thickness of the second mass unit 23. As a result, the degree of freedom in designing the actuator 1 can be further improved, and the detection accuracy of the optical sensor 10 can be improved.
Further, since the light receiving element 122 is configured to receive light through the optical waveguide 121, the diameter of the light receiving unit 12 can be relatively easily reduced even if the second mass unit 23 is thin. Or less. As a result, the degree of freedom in designing the actuator 1 can be further improved, and the detection accuracy of the optical sensor 10 can be improved.

Such an actuator 1 can be manufactured as follows, for example.
10 and 11 are views (longitudinal sectional views) for explaining the manufacturing method of the actuator of the first embodiment. Hereinafter, for convenience of explanation, the upper side in FIGS. 10 and 11 is referred to as “upper” and the lower side is referred to as “lower”.

[A1] First, as shown in FIG. 10A, a silicon substrate 5 is prepared.
Next, on one surface of the silicon substrate 5, as shown in FIG. 10B, for example, a metal mask is formed with aluminum or the like so as to correspond to the shape of the support portion 24 and the mass portions 21, 22, and 23. 6 is formed.
Then, as shown in FIG. 10C, a photoresist is applied to the other surface of the silicon substrate 5, and exposure and development are performed. Thereby, as shown in FIG. 10C, the resist mask 7 is formed so as to correspond to the shape of the support portion 24. The resist mask 7 may be formed before the metal mask 6 is formed.
Examples of the method of forming the metal mask 6 include vacuum plating, sputtering (low temperature sputtering), dry plating methods such as ion plating, wet plating methods such as electrolytic plating and electroless plating, thermal spraying methods, and metal foil bonding. . Note that the same method can also be used for forming a metal film in the following steps.

Next, after etching the other surface of the silicon substrate 5 through the resist mask 7, the resist mask 7 is removed. As a result, as shown in FIG. 10 (d), a recess 51 is formed in a region other than the portion corresponding to the support portion 24.
As an etching method, for example, one or more of physical etching methods such as plasma etching, reactive ion etching, beam etching, and light-assisted etching, and chemical etching methods such as wet etching are used in combination. be able to. Note that the same method can be used for etching in the following steps.

Next, the one surface side of the silicon substrate 5 is etched through the metal mask 6 until a portion corresponding to the recess 51 penetrates.
Then, after removing the metal mask 6, as shown in FIG. 10E, a metal film is formed on the second mass portion 23 to form a light reflecting portion 231.
Here, after etching the silicon substrate 5, the metal mask 6 may be removed or left without being removed. When the metal mask 6 is not removed, the metal mask 6 remaining on the second mass portion 23 can be used as the light reflecting portion 231.

Examples of the method for forming a metal film include vacuum plating, sputtering (low temperature sputtering), dry plating methods such as ion plating, wet plating methods such as electrolytic plating and electroless plating, thermal spraying methods, and joining metal foils. . Note that the same method can also be used for forming a metal film in the following steps.
Through the above steps, as shown in FIG. 10E, the base body 2 in which the respective mass portions 21, 22, 23 and the support portion 24 are integrally formed is obtained.

[A2] Next, as shown in FIG. 11F, a silicon substrate 9 for forming the counter substrate 3 is prepared.
Then, a metal mask is formed on one surface of the silicon substrate 9 with, for example, aluminum so as to correspond to a portion excluding the region where the opening 31 is formed.
Next, after etching one surface side of the silicon substrate 9 through the metal mask, the metal mask is removed. Thereby, the counter substrate 3 in which the opening 31 is formed is obtained.
Thereafter, a film is formed on one surface of the counter substrate 3 with, for example, glass containing movable ions, and the bonding layer 4 is formed on the counter substrate 3 as shown in FIG.

Next, an electrode 32 is formed on the bonding layer 4 as shown in FIG. Thereby, the gap between the electrode 32 and the first mass parts 21 and 22 can be adjusted by adjusting the thickness of the bonding layer 4.
The electrode 32 can be formed by forming a metal film on the bonding layer 4, etching the metal film through a mask corresponding to the shape of the electrode 32, and then removing the mask.

Next, as shown in FIG. 11 (i), the structure obtained in the step [A1] and the counter substrate 3 on which the bonding layer 4 is formed in the step [A2] are bonded by, for example, anodic bonding. Join.
Thereafter, after the optical waveguides 111 and 121 are formed on the base 2, the light emitting element 112 and the light receiving element 122 are attached to obtain the actuator 1.
As a method of forming the optical waveguides 111 and 121, a known optical waveguide forming technique can be used. For example, a first layer is formed on the support portion 24 with the constituent material of the cladding portion, and then the core portion is patterned on the first layer, and then the core portion is covered again with the constituent material of the cladding portion. By forming the second layer in this manner, a clad portion can be formed and an optical waveguide can be obtained.
As described above, the actuator 1 of the first embodiment is manufactured.

Second Embodiment
Next, a second embodiment of the actuator of the present invention will be described.
12 is a plan view showing a second embodiment of the actuator of the present invention, FIG. 13 is a perspective view for explaining an optical sensor provided in the actuator shown in FIG. 12, and FIG. 14 is an actuator shown in FIG. It is a figure for demonstrating operation | movement of the optical sensor with which it was equipped.

The actuator 1A according to the present embodiment is the same as the actuator 1 according to the first embodiment described above except that the configuration of the optical sensor is different.
The actuator 1A according to the present embodiment includes a reflective optical sensor 10A that detects the passage of the side surface (the right side surface in FIG. 12) of the second mass unit 23, and the intensity of light detected by the optical sensor 10A. Based on this, the behavior of the second mass portion 23 is detected.

More specifically, the optical sensor 10A irradiates the light from the light emitting element 112 toward the rotation space of the second mass unit 23 via the optical waveguide 111A and reflects it by the second mass unit 23. The light is received by the light receiving element 122 through the optical waveguide 111A.
More specifically, the optical waveguide 111A has linear core portions 113A and 123A that are optical transmission paths, and a cladding portion 114A that covers the outer periphery of each of the core portions 113A and 123A.
Of both end surfaces of the linear core portion 113 </ b> A, one end surface 115 </ b> A faces the rotation space of the second mass portion 23, and the other end surface 116 </ b> A is connected to the light emitting element 112. Thereby, the light of the light emitting element 112 can be irradiated to the rotation space of the second mass part 23 through the core part 113A.

Of both end surfaces of the linear core portion 123 </ b> A, one end surface 125 </ b> A faces the rotation space of the second mass portion 23, and the other end surface 126 </ b> A is connected to the light receiving element 122. Thereby, the light reflected by the second mass part 23 can be received by the light receiving element 122 through the core part 123A.
In such an optical sensor 10A, as shown in FIGS. 13 and 14A, when the second mass portion 23 is in a non-driven state (home position), the one end surface 115A of the core portion 113A and the core It is located below each of the end surfaces 125A of the part 123A.

When the actuator 1A is in a driving state, the second mass unit 23 reflects light emitted from the one end surface 115A on the side surface of the second mass unit 23 as shown in FIG. After temporarily entering 125A, as shown in FIG. 14C, it reaches a position where the deflection angle becomes maximum.
Thereafter, as shown in FIG. 14 (d), the light emitted from the one end surface 115A is reflected again by the side surface of the second mass portion 23 and temporarily incident on the one end surface 125A. After that, as shown in FIG. 14E, the home position is reached.

As described above, since the second mass unit 23 vibrates and the optical sensor 10A is fixedly arranged, the timing and time length of light reception by the light receiving element 122 from the one end surface 125A through the core unit 123A can be measured. Based on this, the behavior of the second mass unit 23 can be detected.
In this way, the light emitting element 112 (light emitting part) and the light receiving element 122 (light receiving part) are both arranged on one side with respect to the rotational space, and the second mass part 23 as a target thereof is a predetermined one. Only when the rotation angle is reached, the light from the light emitting element 112 is reflected by the side surface of the second mass portion 23 and received by the light receiving element 122. Then, the behavior of the second mass unit 23 is detected based on the presence or absence of light reception by the light receiving element 122.
Even with the actuator 1A as described above, the same effects as those of the actuator 1 according to the first embodiment described above can be obtained.

<Third Embodiment>
Next, a second embodiment of the actuator of the present invention will be described.
FIG. 15 is a plan view showing a third embodiment of the actuator of the present invention.
The actuator 1B according to the present embodiment is the same as the actuator 1A according to the second embodiment described above, except that the detection target of the optical sensor is the first mass unit 22.
More specifically, the actuator 1B according to the present embodiment includes a reflective optical sensor 10B that detects the passage of the side surface (the right side surface in FIG. 15) of the first mass unit 22, and the optical sensor 10B Based on the detected light intensity, the behavior of the second mass unit 23 is detected.

The optical sensor 10B irradiates the light from the light emitting element 112 toward the rotation space of the first mass unit 22 via the optical waveguide 111B, and the light reflected by the first mass unit 22 passes through the optical waveguide 111B. The light receiving element 122 receives light.
More specifically, the optical waveguide 111B has linear core portions 113B and 123B that are optical transmission paths, and a clad portion 114B that covers the outer periphery of each of the core portions 113B and 123B.

Then, the light of the light emitting element 112 is irradiated to the rotation space of the first mass part 22 through the core part 113B, and the light reflected by the first mass part 22 is received by the light receiving element 122 through the core part 123B.
As described above, the first mass unit 22 simply vibrates in correlation with the vibration of the second mass unit 23, and the optical sensor 10B is fixedly arranged, so that the light receiving element 122 receives light through the core unit 123B. Based on the measurement of the timing and the time length, the behavior of the second mass unit 23 can be detected.

As described above, the light emitting element 112 (light emitting part) and the light receiving element 122 (light receiving part) are both arranged on one side with respect to the rotation space of the first mass part 22, and the first of these objects is the first. Only when the mass portion 22 reaches a predetermined rotation angle, the light from the light emitting element 112 is reflected by the side surface of the first mass portion 22 and received by the light receiving element 122. Then, the behavior of the second mass unit 23 is detected based on the presence or absence of light reception by the light receiving element 122.
Even with the actuator 1A as described above, the same effects as those of the actuator 1 according to the first embodiment described above can be obtained.

The actuator as described above can be suitably applied to, for example, a laser printer, a barcode reader, an optical scanner such as a scanning confocal laser microscope, an imaging display, and the like.
Since the actuators of the first to third embodiments as described above are actuators using a torsional vibrator having a two-degree-of-freedom vibration system, they can be manufactured using micromachine technology and can be reduced in size. . In particular, the torsional vibrator having the two-degree-of-freedom vibration system can drive the movable part (second mass part 23) with a large amplitude while reducing the drive voltage.

  The present invention can also be applied to an actuator of a vibration system other than the two-degree-of-freedom vibration system. For example, in the first to third embodiments described above, the first mass portion and the first elastic coupling portion are omitted, and the second mass coupling portion and the support portion are coupled by the second elastic coupling portion. It is good. That is, the present invention can also be applied to an actuator using a torsional vibrator having a one-degree-of-freedom vibration system. Even an actuator using such a torsional vibrator can be manufactured by using micromachine technology, and thus can be miniaturized.

As mentioned above, although the actuator of this invention was demonstrated based on each embodiment of illustration, this invention is not limited to these.
Further, for example, the actuator of the present invention may be configured by combining arbitrary configurations of the first to third embodiments with each other.
In the actuator of the present invention, the configuration of each part can be replaced with an arbitrary configuration that exhibits the same function, and an arbitrary configuration can be added.

  In the above-described embodiment, the first mass portions 21 and 22 are rotated by electrostatic driving, and the second mass portion 23 is rotated accordingly, that is, driving means for driving the movable portion. However, the driving means is not limited to this, and other driving methods such as piezoelectric driving can also be adopted. In addition to the parallel plate type as described above, the driving means using electrostatic driving may have other forms such as those using comb-like electrodes.

It is a top view which shows 1st Embodiment of the actuator of this invention. It is the sectional view on the AA line in FIG. It is the BB sectional view taken on the line in FIG. It is a top view which shows arrangement | positioning of the electrode of the actuator shown in FIG. It is a block diagram which shows the control system of the actuator shown in FIG. It is a figure which shows an example of the drive voltage of the actuator shown in FIG. It is a graph which shows the relationship between the frequency of a drive voltage (alternating current voltage), and the amplitude of a 1st mass part and a 2nd mass part. It is a perspective view for demonstrating the optical sensor with which the actuator shown in FIG. 1 was equipped. It is a figure for demonstrating operation | movement of the optical sensor with which the actuator shown in FIG. 1 was equipped. It is a figure for demonstrating the manufacturing method of the actuator shown in FIG. It is a figure for demonstrating the manufacturing method of the actuator shown in FIG. It is a top view which shows 2nd Embodiment of the actuator of this invention. It is a perspective view for demonstrating the optical sensor with which the actuator shown in FIG. 12 was equipped. It is a figure for demonstrating operation | movement of the optical sensor with which the actuator shown in FIG. 12 was equipped. It is a top view which shows 3rd Embodiment of the actuator of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1, 1A, 1B ... Actuator 2 ... Base | substrate 21, 22 ... 1st mass part 211, 221 ... End part 23 ... 2nd mass part 231 ... Light reflection part 232 ... End part 24 ... ... support part 25 ... first elastic connection part 26 ... second elastic connection part 27 ... rotation axis 28 ... space 3 ... counter substrate 31 ... opening 32 ... electrode 4 ... bonding layer 5 ... Silicon substrate 51 ... Recess 6 ... Metal mask 7 ... Resist mask 9 ... Silicon substrate 10, 10A, 10B ... Optical sensor 11, 11A ... Light emitting part 111, 111A, 111B ... Optical waveguide 112 Light emitting element 113, 113A, 113B Core part 114, 114A, 114B Cladding part 115, 115A One end face 116, 116A Other end face 12 Light receiving part 121 Optical waveguide 12 2 …… Light receiving element 123, 123A …… Core portion 124 …… Clad portion 125, 125A …… One end face 126, 126A …… Other end face 13 …… Energizing circuit 14 …… Control circuit 141 …… CPU 142 …… AD conversion Circuit 143... ROM 144... RAM L ₁ , L ₂ , L _3.

Claims (12)

A plate-like mass part,
A support part for supporting the mass part;
An elastic coupling part that couples the mass part and the support part so that the mass part is rotatable with respect to the support part;
Drive means for rotationally driving the mass part,
An actuator for rotating the mass part while the driving means twists and deforms the elastic connecting part;
Having a behavior detecting means for detecting the behavior of the mass part;
The behavior detection means includes a reflective or transmissive optical sensor that detects passage of a side surface of the mass unit, and is configured to detect the behavior of the mass unit based on a detection result of the optical sensor. An actuator characterized by comprising: A first mass part;
A support part for supporting the first mass part;
A first elastic connecting portion that connects the first mass portion and the support portion so that the first mass portion is rotatable with respect to the support portion;
A second mass part in the form of a plate;
A second elastic connecting portion for connecting the second mass portion and the first mass portion so that the second mass portion is rotatable with respect to the first mass portion;
Drive means for rotationally driving the first mass part;
The drive means rotates the first mass portion while twisting and deforming the first elastic connecting portion, and accordingly, the second mass portion is deformed while twisting and deforming the second elastic connection portion. An actuator to rotate,
Having a behavior detecting means for detecting the behavior of the second mass part;
The behavior detection unit includes a reflective or transmissive optical sensor that detects passage of a side surface of the first mass unit or the second mass unit, and based on a detection result of the optical sensor, An actuator characterized in that it is configured to detect the behavior of the mass part of the actuator.   3. The behavior detecting unit is configured to detect at least one of an amplitude, a frequency, and a displacement amount of vibration of the second mass unit as the behavior of the second mass unit. Actuator.   The optical sensor includes: a light emitting unit that emits light toward a rotation space from a side of the first mass unit or the second mass unit; and a light receiving unit that receives light emitted from the light emitting unit. The actuator according to claim 2, wherein the behavior detecting unit is configured to detect the behavior of the second mass unit based on the intensity of light received by the light receiving unit.   The actuator according to claim 4, wherein the light emitting unit emits light in a direction along a rotation center axis of the first mass unit or the second mass unit.   The light emitting unit and the light receiving unit are arranged with each other through the rotation space, and only when the first mass unit or the second mass unit as a target thereof has a predetermined rotation angle. The light from the light emitting unit to the light receiving unit is blocked by the first mass unit or the second mass unit, and the behavior of the second mass unit is determined based on the presence or absence of light reception by the light receiving unit. The actuator according to claim 4 or 5 to be detected.   The light emitting unit and the light receiving unit are both disposed on one side with respect to the rotation space, and the first mass unit or the second mass unit as the target has a predetermined rotation angle. Only when the light from the light emitting part is reflected by the side surface of the first mass part or the second mass part and received by the light receiving part, based on the presence or absence of light reception by the light receiving part, The actuator according to claim 4, wherein the behavior of the second mass part is detected.   The light emitting unit and the light receiving unit are arranged so as to be shifted in the plate thickness direction with respect to the first mass unit or the second mass unit in a non-driven state as a target. The actuator according to Crab.   The said light emission part has a light emitting element and an optical waveguide, and the said light emitting element is comprised so that light may be irradiated to the said rotation space via the said optical waveguide. Actuator.   The actuator according to claim 4, wherein the light receiving unit includes a light receiving element and an optical waveguide, and the light receiving element is configured to receive light through the optical waveguide.   The actuator according to claim 2, wherein the second mass unit has a light reflecting unit.   The actuator according to any one of claims 2 to 11, further comprising a control unit that controls driving of the driving unit based on a behavior detected by the behavior detecting unit.

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