JP2005279863A - Actuator manufacturing method and actuator - Google Patents

Abstract

An object of the present invention is to provide an inexpensive actuator manufacturing method and actuator that can be driven at a low voltage and have a large deflection angle (amplitude).
A first step of forming recesses 28 and 29 by etching one surface of a substrate 2 made of silicon as a main material, and a portion corresponding to the recesses 28 and 29 in the substrate 2 are etched. By doing so, it has the 2nd process of forming the 1st mass parts 21 and 22, the 2nd mass part 23, support part 24, the 1st elastic connection part 25, and the 2nd elastic connection part 26.
[Selection] Figure 2

Description

  The present invention relates to an actuator manufacturing method and an actuator.

For example, a polygon mirror (rotating polyhedron) is known as an actuator used in a laser printer or the like.
However, in such a polygon mirror, in order to achieve high-quality, high-quality printing and high-speed printing, the polygon mirror must be rotated at a higher speed.
In current polygon mirrors, air bearings are used to maintain high-speed and stable rotation, but it is difficult to obtain higher-speed rotation. In addition, in order to increase the speed, a large motor is required, which is disadvantageous in terms of downsizing the device.

When such a polygon mirror is used, there is a problem that the structure becomes complicated and the cost becomes high.
Further, a one-degree-of-freedom torsional vibrator in which electrodes are arranged in a parallel plate shape as shown in FIG. 14 has been proposed from the early stage of research on actuators (for example, Non-Patent Document 1). reference). In addition, a one-degree-of-freedom electrostatic drive type vibrator in which the torsional vibrator is a cantilever type has been proposed (see, for example, Non-Patent Document 2).

  The one-degree-of-freedom electrostatic drive type torsional vibrator of FIG. 14 fixes both end fixing portions 1300a of a movable electrode plate 1300 made of a silicon single crystal plate to both ends on a glass substrate 1000 via a spacer 1200, A fixed electrode 1400 that supports the movable electrode portion 1300c via a narrow torsion bar 1300b between the both-end fixed portions 1300a of the movable electrode plate 1300 and faces the movable electrode portion 1300c with an electrode interval therebetween, On the glass substrate 1000, it arrange | positions in parallel with respect to the said movable electrode part 1300c. A power source 1500 is connected between the movable electrode plate 1300 and the fixed electrode 1400 via a switch 1600.

  In the torsional vibrator having the above-described configuration, when a voltage is applied between the movable electrode portion 1300c and the fixed electrode 1400, the movable electrode portion 1300c rotates about the torsion bar 1300b as an axis by electrostatic attraction. However, since the electrostatic attractive force is inversely proportional to the square of the electrode interval, it is desirable to reduce the electrode interval in this type of electrostatic actuator. However, in the above-described one-degree-of-freedom structure, the movable electrode portion 1300c serves as both an electrode and a movable portion. Need to be larger. For this reason, there is a problem that it is difficult to achieve both low voltage driving and large amplitude.

K.E.Petersen: “Silicon Torsional Scanning Mirror”, IBM J. Res. Development., Vol. 24 (1980), p. 631 Kawamura et al .: “Research of micromechanics using Si”, Proceedings of the 1986 Fall Meeting of the Japan Society for Precision Engineering, p.753

  An object of the present invention is to provide an inexpensive actuator manufacturing method and actuator that can be driven at a low voltage and have a large deflection angle (amplitude).

Such an object is achieved by the present invention described below.
The manufacturing method of the actuator of the present invention includes a first mass unit, a second mass unit, a support unit, and the first mass unit so that the first mass unit is rotatable with respect to the support unit. The first mass so that the at least one pair of first elastic connecting portions for connecting the mass portion and the support portion and the second mass portion can be rotated with respect to the first mass portion. And at least a pair of second elastic connecting portions that connect the second mass portion and the first mass portion is rotationally driven by application of an alternating voltage, and accompanying this rotational driving A method of manufacturing a two-degree-of-freedom vibration system actuator in which the second mass part is rotated,
A first step of forming a recess by etching one surface of a first substrate composed mainly of silicon;
Etching a portion of the first substrate corresponding to the concave portion allows the first mass portion, the second mass portion, the support portion, the first elastic coupling portion, and the second elastic coupling. And a second step of forming the part.

Thereby, the recessed part formed in the 1st board | substrate can ensure sufficient space which can vibrate (rotate) the 1st mass part and the 2nd mass part. Further, the formation of the concave portion can reduce the mass of the first mass portion and the second mass portion.
For this reason, the obtained actuator can be driven at a low voltage and can have a large deflection angle (amplitude).
Furthermore, since the first substrate formed using silicon as a main material is relatively inexpensive, the manufacturing cost can be reduced.

The method for manufacturing an actuator of the present invention includes a third step of bonding the second substrate to the first substrate so as to cover the concave portion of the first substrate after the second step. Is preferred.
As a result, a space in which the first mass unit and the second mass unit can vibrate (turn) is formed on the second substrate.

In the actuator manufacturing method of the present invention, in the first step, the recess is formed at a depth that does not prevent the second substrate from rotating the first mass portion and the second mass portion. It is preferable.
As a result, even if the second substrate has a simple plate shape, a space where the first mass portion and the second mass portion can vibrate (turn) can be formed on the second substrate.

In the method for manufacturing an actuator of the present invention, it is preferable that an electrode is provided in a portion corresponding to the first mass part in the second substrate prior to the third step.
Thereby, the 1st mass part can be rotationally driven by applying an alternating voltage to the electrode provided in the 2nd substrate.
In the actuator manufacturing method of the present invention, it is preferable to form another recess by etching on the other surface of the first substrate prior to the second step.
Accordingly, the concave portions formed on both surfaces of the first substrate ensure sufficient space on both sides of the first substrate where the first mass portion and the second mass portion can vibrate (turn). Can do.

In the actuator manufacturing method of the present invention, a third substrate is bonded to the first substrate so as to cover the other concave portion, and the first substrate, the second substrate, and the third substrate are bonded to each other. It is preferable to form an airtight space that accommodates the first mass portion, the second mass portion, the first elastic coupling portion, and the second elastic coupling portion by joining the first and second mass portions.
Thereby, it is possible to prevent foreign matters such as dust from entering the inside of the actuator (inside the recess). In addition, air resistance generated when the first mass portion and the second mass portion vibrate (rotate) when the inside of the actuator (inside the recess) is in a reduced pressure state or filled with an inert gas or the like. And a larger touch angle can be realized.

In the actuator manufacturing method of the present invention, it is preferable that the third substrate is made of glass as a main material.
Thus, the actuator can be an optical scanner by providing the reflecting mirror on the surface of the second mass portion on the third substrate side.
The actuator of the present invention is manufactured using the manufacturing method of the present invention.
Thus, an inexpensive actuator that can be driven at a low voltage and has a large deflection angle (amplitude) can be obtained.

The actuator according to the present invention includes a first mass unit, a second mass unit, a support unit, and the first mass unit so that the first mass unit is rotatable with respect to the support unit. And at least a pair of first elastic connecting portions for connecting the support portion and the first mass portion and the second mass portion so that the second mass portion is rotatable with respect to the first mass portion. And at least a pair of second elastic connecting portions that connect the second mass portion, and the first mass portion is rotationally driven by application of an alternating voltage, and the second mass is accompanied by the rotational driving. A two-degree-of-freedom vibration actuator in which a mass part of the actuator is rotated,
The first mass portion, the second mass portion, the support portion, the first elastic coupling portion, and the second elastic coupling portion are provided in a base body mainly composed of silicon,
A recess is formed on at least one surface of the substrate,
The first mass portion, the second mass portion, the first elastic coupling portion, and the second elastic coupling portion are provided in a portion of the base corresponding to the concave portion. .
Thus, an inexpensive actuator that can be driven at a low voltage and has a large deflection angle (amplitude) can be obtained.

In the actuator of the present invention, the two-degree-of-freedom vibration system includes a pair of the first mass parts,
One of the pair of first mass parts is preferably provided on one end side of the second mass part, and the other is provided on the other end side of the second mass part.
As a result, it is possible to more reliably drive at a low voltage and to have a large deflection angle (amplitude).

In the actuator of the present invention, the rotation center axis of the one first mass portion and the end portion in the direction substantially perpendicular to the rotation center axis of the one first mass portion. distance and L _1, and the rotational axis of the first mass of the other, with respect to the central axis of rotation of the first mass portion of said other, between the substantially vertical direction of the end portion The distance is L _2, and the distance between the rotation center axis of the second mass unit and the end of the second mass unit in the direction substantially perpendicular to the rotation center axis is L _3. In this case, it is preferable that L ₁ and L ₃ satisfy the relationship L ₁ <L ₃ , and L ₂ and L ₃ satisfy the relationship L ₂ <L ₃ .
As a result, low-voltage driving can be performed more easily and reliably, and the deflection angle (amplitude) can be increased.

The actuator of the present invention, and the distance L _1, it is preferable that said distance L ₂ is approximately equal.
As a result, the actuator can be easily controlled, and can be driven easily and reliably at a low voltage, and the deflection angle (amplitude) can be increased.
In the actuator of the present invention, the frequency of the AC voltage is set to be substantially equal to the lower one of the resonance frequencies of the two-degree-of-freedom vibration system in which the first mass unit and the second mass unit resonate. It is preferable.
As a result, high-speed operation can be performed at a low voltage, and the deflection angle (amplitude) can be increased. Moreover, by setting it as such a structure, the rotation angle (deflection angle) of a 2nd mass part can be enlarged, suppressing the amplitude of a 1st mass part.

In the actuator according to the present invention, when the spring constant of the first elastic coupling portion is k ₁ and the spring constant of the second elastic coupling portion is k ₂ , k ₁ and k ₂ are k ₁ > k. It is preferable that the relationship of ₂ is satisfied.
Thereby, the rotation angle (deflection angle) of the second mass part can be increased while suppressing the deflection angle (amplitude) of the first mass part.

In the actuator according to the aspect of the invention, it is preferable that in the two-degree-of-freedom vibration system, at least one of the first elastic connection portion and the second elastic connection portion includes a piezoresistive element therein.
Thereby, for example, the rotation angle and the rotation frequency can be detected, and the detection result can be used for controlling the attitude of the second mass unit.

The actuator of the present invention, the moment of inertia of the first mass and J _1, when the moment of inertia of the second mass was J _2, J ₁ and J ₂ and the J ₁ ≦ J ₂ the relationship Is preferably satisfied.
Thereby, the rotation angle (swing angle) of the second mass unit can be increased while suppressing the amplitude of the first mass unit.

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 and the manufacturing method thereof will be described.
1 is a plan view (internal perspective 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, and FIG. 3 is an electrode of the actuator shown in FIG. FIG. 4 is a diagram showing an example of the applied AC voltage, and FIG. 5 is a graph showing the frequency of the applied AC voltage and the resonance curves of the first mass part and the second mass part. is there. In the following, for convenience of explanation, the front side of the page in FIGS. 1 and 3 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 called “upper”, the lower side is called “lower”, the right side is called “right”, and the left side is called “left”.

The actuator 1 has a base 2 having a two-degree-of-freedom vibration system as shown in FIG. 1, and a bottom member 3 is joined to the lower part of the base 2 as shown in FIG. A light-transmitting lid member 4 is joined to the upper portion of 2.
That is, in the actuator 1 of the present embodiment, a two-degree-of-freedom vibration system of the base 2 described later is driven between the bottom member 3 and the lid member 4.

The base 2 includes a pair of first mass units (drive units) 21 and 22 and a second mass unit (movable unit) 23 in which a light reflecting unit 231 is provided on the upper surface (surface on the lid member 4 side described later). And a frame-shaped support portion 24 surrounding 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, 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.

  Such a two-degree-of-freedom vibration system is formed thinner than the entire thickness of the base 2 and is located at the center of 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.

The thin portion is formed in the base 2 by providing the base 2 with a recess 28 that opens upward and a recess 29 that opens downward. In the present embodiment, the depth of the recess 28 and the depth of the recess 29 are substantially the same.
Such a base body 2 is composed of silicon as a main material, and includes first mass portions 21, 22, second mass portions 23, a support portion 24, and first elastic coupling portions 25, 25. The second elastic connecting portions 26 and 26 are integrally formed. As a result, (1) the manufacturing process is reduced and the cost is reduced. (2) Since it is an integrated type, failure such as cracks can be avoided. (3) Design as an elastic body becomes easy.

The bottom member 3 is composed of, for example, various types of glass and silicon as a main material.
As shown in FIGS. 2 and 3, a recess 31 is formed on the top surface of the bottom member 3 at a portion corresponding to the second mass portion 23.
The recess 31 constitutes an escape portion that prevents the second mass portion 23 from contacting the bottom member 3 when the second mass portion 23 rotates (vibrates). By providing the concave portion (relief 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 addition, when the depth of the recessed part 29 is large with respect to the deflection angle (amplitude) of the 2nd mass part 23, the recessed part 31 does not need to be provided.

  Further, as shown in FIG. 3, a pair of electrodes 32 are provided on the upper surface of the bottom member 3 so as to be substantially symmetrical about the rotation center axis 27 at a portion corresponding to the first mass portion 21. In addition, a pair of electrodes 32 is provided in a portion corresponding to the first mass portion 22 so as to be substantially symmetric about the rotation center axis 27. That is, in the present 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 a power source (not shown) so that an alternating voltage (drive voltage) can be applied between the first mass parts 21 and 22 and each electrode 32. It is configured.
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 lid member 4 has a function of causing external light to enter the light reflecting portion 231 and deriving light reflected by the light reflecting portion 231 to the outside. For this reason, the cover member 4 is comprised with the board | substrate which was excellent in flatness and excellent in the light transmittance, for example, various glass substrates.
In the actuator 1 of this embodiment, the base body 2, the bottom member 3, and the lid member 4 form an airtight space. Specifically, the recess 31 and the recesses 28 and 29 communicate with each other, and these form an airtight space. In such an airtight space, the above-described first mass parts 21, 22, the second mass part 23, the support part 24, the first elastic connection parts 25, 25, and the second elastic connection parts 26, 26 are provided. It is arranged.

With such a configuration, I: It is easy to secure a space where the first mass parts 21 and 22 and the second mass part 23 can vibrate.
II: Foreign matter such as dust can be prevented from entering the actuator 1 (in the airtight space). III: The first mass parts 21 and 22 and the second mass part 23 vibrate (rotate) when the inside of the actuator 1 (in the airtight space) is in a reduced pressure state or filled with an inert gas or the like. ), The air resistance generated at the time is reduced, and vibration (rotation) at a larger angle becomes possible. As a result, the actuator 1 can be made highly reliable.

  Furthermore, IV: Since it is not necessary to process the lid member 4 by etching or the like to secure a space in which the first mass portions 21 and 22 and the second mass portion 23 can vibrate, the surface of the lid member 4 ( In particular, the flatness of the recess 28 side is ensured (that is, the surface is prevented from being roughened). Thereby, in the cover member 4, it is prevented or reduced that incident light and reflected light are scattered etc., As a result, the actuator 1 can obtain a high reflectance.

Here, there are various indexes indicating the flatness of the surface of the lid member 4. For example, surface roughness (centerline average roughness specified in JIS B 0601) Ra is preferably used.
Specifically, the surface roughness Ra of the lid member 4 is preferably 1 μm or less, more preferably 100 nm or less, and even more preferably about 1 nm to 100 nm. If the surface roughness exceeds the upper limit, depending on the constituent material and thickness of the lid member 4, the loss of incident light and reflected light may increase, and sufficient reflectivity may not be obtained.

  The average depth of the recesses 28 and 29 is appropriately set according to the dimensions of the first mass parts 21 and 22 and the second mass part 23 (actuator 1), and is not particularly limited, but is about 1 to 2000 μm. It is preferable that it is about 5-10 micrometers. If the average depth is too thin, it is not possible to ensure a sufficient distance between the mass parts 21, 22, 23 and the bottom member 3 or the lid member 4, and the touch angle of each mass part 21, 22, 23 ( It may be difficult to set a large displacement angle. On the other hand, if the average depth is too thick, the distances between the respective mass portions 21, 22, 23 and the bottom member 3 and the lid member 4 become unnecessarily large, leading to an increase in size of the actuator 1, which is not preferable.

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. 4A is applied to the upper two electrodes 32 in FIG. A voltage having a waveform as shown in FIG. 4B is applied to the 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).

Here, in the actuator 1, as described above, the concave portion 31 is formed in the portion corresponding to the second mass portion 23 of the bottom member 3, and the concave portion 29 is formed on the lower surface of the base 2 in FIG. A concave portion 28 is formed on the upper surface, and the first mass portions 21 and 22 are provided in the concave portions 28 and 29 in a 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 the respective mass parts 21, 22, and 23 (two-degree-of-freedom vibration system) from contacting the bottom member 3 and the lid member 4.

For this reason, when such an actuator 1 is applied to, for example, an optical scanner, scanning with higher resolution can be performed.
Here, with respect to the rotational axis 27 of the first mass portion 21, and a substantially perpendicular distance (length) between the end 211 of the (longitudinal) and L _1, first mass 22 with respect to the rotational axis 27 of the substantially vertical direction by a distance (length) between the end 221 of the (longitudinal) and L _2, the rotation center axis 27 of the second mass 23 in contrast, when the distance between the end 232 of the substantially vertical direction (length) was set to L _3, in this embodiment, the first mass portions 21 and 22 are provided independently of each other Therefore, the first mass parts 21 and 22 and the second mass part 23 do not interfere with each other, and L ₁ and L ₂ are reduced regardless of the size (length L ₃ ) of the second mass part 23. can do. 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, it is preferable that the dimensions of the first mass parts 21 and 22 and the second mass part 23 are set so as to satisfy the relationship of L ₁ <L ₃ and L ₂ <L ₃ , respectively.

By satisfying the above relationship, L ₁ and L ₂ can be further reduced, the rotation angle of the first mass parts 21 and 22 can be further increased, and the rotation angle of the second mass part 23 is further increased. Can be bigger.
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. 5 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 portion 25 is preferably 1 × 10 ⁻⁴ to 1 × 10 ⁴ Nm / rad, and preferably 1 × 10 ⁻² to 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.
In the vibration system of the present embodiment, it is preferable that at least one of the pair of first elastic coupling portions 25 and the pair of second elastic coupling portions 26 includes a piezoresistive element therein. . Thereby, for example, the rotation angle and the rotation frequency can be detected, and the detection result can be used for controlling the posture of the second mass unit 23.
Such an actuator 1 can be manufactured as follows, for example.
6 to 9 are views (longitudinal sectional views) for explaining the manufacturing method of the actuator of the first embodiment. In the following, for convenience of explanation, the upper side in FIGS. 6 to 9 is referred to as “upper” and the lower side is referred to as “lower”.

[A1] First, as shown in FIG. 6A, a silicon substrate 5 as a first substrate is prepared.
And as shown in FIG.6 (b), a photoresist is apply | coated to both surfaces of the silicon substrate 5, and exposure and image development are performed. Thereby, as shown in FIG. 6B, the resist mask 6 is formed so as to correspond to the shape of the support portion 24.
Next, after etching both surfaces of the silicon substrate 5 through the resist mask 6, the resist mask 6 is removed. Thereby, as shown in FIG.6 (c), the recessed part 51 is formed in area | regions other than the part corresponding to the support part 24 (1st process). At that time, the etching may be performed simultaneously on both sides of the silicon substrate 5 or may be performed on each side. When the silicon substrate 5 is etched one side at a time, either the etching of one surface on the side where the metal mask 7 described later is formed or the etching of the other surface may be performed.

  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, on one surface of the silicon substrate 5, as shown in FIG. 7 (d), for example, a metal mask is formed with aluminum or the like so as to correspond to the shapes of the support portion 24 and the mass portions 21, 22, and 23. 7 is formed.
Next, the one surface side of the silicon substrate 5 is etched through the metal mask 7 until a portion corresponding to the recess 51 penetrates (second step).

When the metal mask 7 is removed, thereafter, a metal film is formed on the second mass portion 23 to form the light reflecting portion 231.
Here, after etching the silicon substrate 5, the metal mask 7 may be removed or may be left without being removed. When the metal mask 7 is not removed, the metal mask 7 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. 7E, a structure in which the respective mass portions 21, 22, 23 and the support portion 24 are integrally formed, that is, the base 2 is obtained.

[A2] Next, as shown in FIG. 8F, a silicon substrate 9 as a second substrate for forming the bottom member 3 is prepared. Note that a glass substrate or the like may be used instead of the silicon substrate 9.
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 recess 31 is formed.
Next, after etching one surface side of the silicon substrate 9 through the metal mask, the metal mask is removed. Thereby, as shown in FIG.8 (g), the bottom member 3 in which the recessed part 31 was formed is obtained.

Next, an electrode 32 is formed on the bottom member 3 as shown in FIG.
The electrode 32 is formed by forming a metal film on the surface of the bottom member 3 where the recess 31 is formed, etching the metal film through a mask corresponding to the shape of the electrode 32, and then removing the mask. can do.
Next, as shown in FIG. 9 (i), the base body 2 and the bottom member 3 of the structure obtained in the step [A1] are joined by, for example, direct joining to obtain a joined body (third Process). When a glass substrate is used instead of the silicon substrate 9, the base 2 and the bottom member 3 are joined by anodic bonding.

[A3] Next, as shown in FIG. 9 (j), the joined body obtained in the step [A2] and the lid member 4 (preferably a glass substrate) as the third substrate are bonded by, for example, anodic bonding. Join.
As described above, the actuator 1 of the first embodiment is manufactured.
In such a manufacturing method, since the base body 2 is manufactured only from an inexpensive silicon substrate 5 made mainly of silicon without using an expensive SOI substrate, the actuator 1 can be obtained at low cost.

Moreover, by forming the recessed part 51 (recessed part 29) in the 1st board | substrate 5 (base | substrate 2), while contacting each mass part 21,22,23 and the bottom member 3, each mass part 21,22 is prevented. , 23 can be reduced in mass, so that the drive voltage can be lowered and the mass portions 21, 22, 23 can be increased in frequency.
Further, by forming the recess 51 (recess 28) in the first substrate 5 (base 2), the lid member 4 is joined to the base 2 without being processed, so that the flatness of the surface of the lid member 4 is ensured. be able to. Thereby, in the cover member 4, it is prevented or reduced that incident light and reflected light are scattered etc., As a result, the actuator 1 can obtain a high reflectance.

  Moreover, the formation process of the recessed part 28 and the joining process of the base | substrate 2 and the cover member 4 are processes which can be performed more simply than the process of processing the cover member 4 by an etching etc. In addition, by setting the depth of the recess 28, the distances between the first mass parts 21 and 22 and the second mass part 23 and the lid member 4 can be easily set to a desired one. Therefore, according to the manufacturing method as described above, the manufacturing process of the actuator 1 can be simplified.

Second Embodiment
Next, a second embodiment of the actuator of the present invention will be described.
FIG. 10 is a longitudinal sectional view showing the actuator of the second embodiment. In the following, for convenience of explanation, the upper side in FIG. 10 is referred to as “upper”, the lower side as “lower”, the right side as “right”, and the left side as “left”.

Hereinafter, the actuator of the second embodiment will be described focusing on the differences from the actuator of the first embodiment, and the description of the same matters will be omitted.
The actuator 1 of the second embodiment is the same as the actuator 1 of the first embodiment, except that the recess 28 is formed by the base 2 ′ and the spacer 241.
That is, in the base body 2 ′ shown in FIG. 10, the upper surface of each mass part 21, 22, 23 and the upper surface of the support part 24 ′ are located on the same plane, and a frame-like spacer corresponding to the shape of the support part 24 ′. A concave portion 28 is formed by bonding 241 to the upper surface of the support portion 24.

Also with the actuator 1 of the second embodiment, the same operation and effect as the actuator of the first embodiment can be obtained.
Further, such an actuator 1 omits the step for forming the recess on the upper surface of the base 2 and performs the above-described first process except for performing the steps for forming the spacer 241 and joining the spacer 241 and the base 2. It can be manufactured by the same method as the embodiment.

<Third Embodiment>
Next, a third embodiment of the actuator of the present invention will be described.
FIG. 11 is a plan view (internal perspective view) showing a third embodiment of the actuator of the present invention. In the following, for convenience of explanation, the front side of the paper in FIG. 11 is referred to as “up”, the back side of the paper is referred to as “down”, the right side is referred to as “right”, and the left side is referred to as “left”.

Hereinafter, the actuator of the third embodiment will be described focusing on the differences from the actuator of the first embodiment, and the description of the same matters will be omitted.
The actuator 1 of the third embodiment is different in the connecting structure of the support part 24, the first mass parts 21 and 22, and the second mass part 23, and otherwise the actuator 1 of the first embodiment. It is the same.

That is, as shown in FIG. 11, the first mass parts 21 and 22 are connected to the support part 24 via two pairs of first elastic connection parts 25 ′, and the second mass part 23 is the first mass part 23. Are connected to the mass portions 21 and 22 via two pairs of second elastic connecting portions 26 '.
Also with the actuator 1 of the third embodiment, the same operation and effect as the actuator of the first embodiment can be obtained.

In particular, in the present embodiment, the first mass parts 21 and 22 and the second mass part 23 are connected to each other via two pairs of elastic connection parts, so that the second mass part 23 is more reliably connected. Can be controlled.
Incidentally, as in this embodiment, when having 'the second elastic connecting portions 26 of the two pairs' first elastic connecting portions 25 of the two pairs, the spring constant k _1, k ₂ described in the embodiment The two elastic connecting portions that are connected at substantially the same position are considered to be integrated.
In addition, in the manufacturing process of the base body 2 ″, such an actuator 1 has the same configuration as that of the first elastic connecting portion 25 ′ and the second elastic connecting portion 26 ′ as described above. It can be manufactured by the same method as in the first embodiment described above.

<Fourth embodiment>
Next, a fourth embodiment of the actuator of the present invention will be described.
FIG. 12 is a plan view (internal perspective view) showing a fourth embodiment of the actuator of the present invention. In the following, for convenience of explanation, the front side of the sheet in FIG. 12 is referred to as “upper”, the rear side of the sheet is referred to as “lower”, the right side is referred to as “right”, and the left side is referred to as “left”.

Hereinafter, the actuator of the fourth embodiment will be described focusing on the differences from the actuator of the first embodiment, and the description of the same matters will be omitted.
The actuator 1 of 4th Embodiment is comprised so that it may drive by electromagnetic force (Lorentz force), and other than that is the same as that of the actuator 1 of the said 1st Embodiment.
That is, the actuator 1 shown in FIG. 12 includes four terminals 10 provided on the support portion 24 via an insulating film (not shown), and upper surfaces of the first mass portions 21 and 22 (surface on the lid member 4 side). ) And a pair of permanent magnets 40 arranged opposite to each other (substantially symmetrically) around the elastic coupling portion (rotation center shaft 27) via the first mass portions 21 and 22. doing.

The pair of permanent magnets 40 are attached to the upper surface of the bottom member 3 so that the S pole and the N pole face each other.
The end of the coil 20 is connected to the terminal 10.
The terminal 10 is connected to a power source (not shown) so that an AC voltage can be applied to the coil 20.

In the actuator 1, when an AC voltage is applied to the coil 20, an electromagnetic force is generated between the coil 20 (first mass parts 21, 22) and the permanent magnet 40, and the first mass part 21 is generated by the electromagnetic force. , 22 is rotated (driven), and the second mass portion 23 is rotated (driven) as the first mass portions 21, 22 are driven.
Also by the actuator 1 of the fourth embodiment, the same operation and effect as the actuator of the first embodiment can be obtained.

<Fifth Embodiment>
Next, a fifth embodiment of the actuator of the present invention will be described.
FIG. 13 is a plan view (internal perspective view) showing a fifth embodiment of the actuator of the present invention. In the following, for convenience of explanation, the front side in FIG. 13 is referred to as “up”, the back side in FIG. 13 is referred to as “down”, the right side is referred to as “right”, and the left side is referred to as “left”.

Hereinafter, the actuator of the fifth embodiment will be described focusing on the differences from the actuator of the first embodiment, and the description of the same matters will be omitted.
The actuator 1 of the fifth embodiment is configured to be driven by a piezo actuator, and is otherwise the same as the actuator 1 of the first embodiment.
That is, in the actuator 1 shown in FIG. 13, one piezo actuator (actuator provided with a piezoelectric element) 400 is provided at each end of the upper surface (surface on the lid member 4 side) of the first mass portions 21 and 22. It has been.

In the actuator 1, the first mass parts 21 and 22 are distorted (expanded / contracted) by driving the piezo actuator 400, and the second mass part 23 is rotated (driven) by the distortion.
Also with the actuator 1 of the fifth embodiment, the same operation and effect as the actuator of the first embodiment can be obtained.

  In particular, in the present embodiment, by providing the piezo actuator 400 in the first mass parts 21 and 22, the electrode 32 is not necessary, and the production cost can be reduced. Further, by eliminating the need for the electrode 32, the dimension of the concave portion 31 in the left-right direction can be increased to a position corresponding to the first mass portions 21 and 22. Thereby, the rotation angle of the 1st mass parts 21 and 22 can be enlarged more.

  In the present embodiment, one (one layer) piezo actuator 400 is provided in the first mass parts 21, 22. However, the present invention is not limited to this. For example, a bimorph piezo actuator (two-layer piezo actuator) Among them, two (two layers) or more piezoelectric actuators such as an actuator that generates a flexural vibration that vibrates one piezoelectric actuator in the compression direction and vibrates the other piezoelectric actuator in the extension direction may be provided.

In the present embodiment, the piezo actuator 400 is provided at the end of the upper surface of the first mass unit 21, 22. However, the present invention is not limited to this, for example, on the entire upper surface of the first mass unit 21, 22. You may provide, and you may provide in the edge part or the whole surface of the lower surface (surface by the side of the bottom member 32) of the 1st mass parts 21 and 22. FIG.
The actuator 1 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.

As mentioned above, although the actuator of this invention was demonstrated based on each embodiment of illustration, this invention is not limited to these.
For example, the actuator of the present invention may be combined with any two or more configurations of the first to fifth embodiments.
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.

Moreover, in embodiment mentioned above, although demonstrated as what has 1st or 2 pairs of 1st elastic connection parts, it is not limited to this, For example, 3 pairs or more may be sufficient.
Moreover, in embodiment mentioned above, although demonstrated as what has a 1st or 2nd 2nd elastic connection part, it is not limited to this, For example, 3 or more pairs may be sufficient.
In the above-described embodiment, the configuration in which the light reflecting portion 231 is provided on the surface of the second mass portion 23 on the lid member 33 side has been described. For example, the configuration is provided on the opposite surface. There may be a configuration provided on both sides.

In the first to third embodiments described above, the configuration in which the electrode 32 is provided on the bottom member 3 has been described. However, the electrode 32 is provided on both the bottom member 3 and the first mass portions 21 and 22. Also good.
In the first to third embodiments described above, a pair of electrodes 32 is provided at positions corresponding to the first mass parts 21 and 22, but not limited thereto, one electrode 32, respectively. Or three or more may be provided.

When one electrode 32 is provided at a position corresponding to each of the first mass parts 21 and 22, for example, an offset voltage is added, and a sine wave (AC voltage) whose minimum potential is the ground potential is used. It is preferable to apply.
In the above-described embodiment, the shape of the first elastic coupling portion and the second elastic coupling portion has been described with respect to the illustrated configuration. However, the shape is not limited thereto. For example, the shape is a crank shape or the like. It may have a branched structure.

In the first to third embodiments described above, the configuration in which the insulating film for preventing a short circuit is provided on the surface of the first mass portion 21, 22 facing the electrode 32 has been described. Such an insulating film may be provided on the surface of the electrode 32, or may be provided on both.
In the fourth embodiment described above, the configuration in which the coil 20 is provided on the surface of the first mass portions 21 and 22 on the lid member 4 side has been described. For example, the coil 20 is provided on the opposite surface. Alternatively, it may be provided inside the first mass parts 21 and 22.
In the above-described embodiment, the pair of first mass parts is provided. However, the first mass part is configured to surround the second mass part. Also good.

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 a top view which shows arrangement | positioning of the electrode of the actuator shown in FIG. It is a figure which shows an example of the alternating voltage to apply. It is a graph which shows the frequency of the applied alternating voltage, and the resonance curve of the 1st mass part and the 2nd mass part. It is a figure for demonstrating the manufacturing method of the actuator of 1st Embodiment. It is a figure for demonstrating the manufacturing method of the actuator of 1st Embodiment. It is a figure for demonstrating the manufacturing method of the actuator of 1st Embodiment. It is a figure for demonstrating the manufacturing method of the actuator of 1st Embodiment. It is a longitudinal cross-sectional view which shows 2nd Embodiment of the actuator of this invention. It is a top view which shows 3rd Embodiment of the actuator of this invention. It is a top view which shows 4th Embodiment of the actuator of this invention. It is a top view which shows 5th Embodiment of the actuator of this invention. It is a figure for demonstrating the conventional actuator.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... 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 241 …… Spacer 25, 25 ′ …… First elastic connecting portion 26, 26 ′ …… Second elastic connecting portion 27 …… Rotation center shaft 28, 29 …… Concavity 3 …… Bottom member 31 …… Concavity 32 …… Electrode 4 …… Cover member 5 …… Silicone substrate 51 …… Concavity 6 …… Resist mask 7 …… Metal mask 9 …… Silicone substrate 10 …… Terminal 20 …… Coil 40 …… Permanent magnet 400 …… Piezo actuator 1200 ...... spacer 1300 ...... movable electrode plate 1300a ...... both end fixing portions 1300b ...... torsion bars 1300c ...... movable electrode portion 1400 ...... stationary electrode 1500 ...... power 1600 ...... switch L _{1 L 2,} L ₃ ...... distance

Claims (16)

The first mass unit, the second mass unit, the support unit, and the first mass unit and the support unit so that the first mass unit is rotatable with respect to the support unit. At least a pair of first elastic connecting portions to be connected, and the first mass portion and the second mass portion so that the second mass portion can be rotated with respect to the first mass portion; And at least a pair of second elastic connecting portions, and by applying an alternating voltage, the first mass portion is rotationally driven, and the second mass portion is rotated by the rotational driving. A method for manufacturing a two-degree-of-freedom vibration system actuator,
A first step of forming a recess by etching one surface of a first substrate composed mainly of silicon;
Etching a portion of the first substrate corresponding to the concave portion allows the first mass portion, the second mass portion, the support portion, the first elastic coupling portion, and the second elastic coupling. And a second step of forming the portion.   The method for manufacturing an actuator according to claim 1, further comprising a third step of bonding the second substrate to the first substrate so as to cover the concave portion of the first substrate after the second step. .   3. The manufacturing of the actuator according to claim 2, wherein, in the first step, the recess is formed at a depth that does not prevent the second substrate from rotating the first mass portion and the second mass portion. Method.   4. The method for manufacturing an actuator according to claim 2, wherein an electrode is provided in a portion of the second substrate corresponding to the first mass portion prior to the third step. 5.   5. The method for manufacturing an actuator according to claim 2, wherein another recess is formed on the other surface of the first substrate by etching prior to the second step.   A third substrate is bonded to the first substrate so as to cover the other concave portion, and the first mass is obtained by bonding the first substrate, the second substrate, and the third substrate. The method for manufacturing an actuator according to claim 5, wherein an airtight space is formed to accommodate a portion, the second mass portion, the first elastic coupling portion, and the second elastic coupling portion.   The method for manufacturing an actuator according to claim 6, wherein the third substrate is made of glass as a main material.   An actuator manufactured using the manufacturing method according to claim 1. The first mass unit, the second mass unit, the support unit, and the first mass unit and the support unit so that the first mass unit is rotatable with respect to the support unit. The at least one pair of first elastic coupling portions to be coupled, and the first mass portion and the second mass portion so that the second mass portion is rotatable with respect to the first mass portion; And at least a pair of second elastic connecting portions, and by applying an alternating voltage, the first mass portion is rotationally driven, and the second mass portion is rotated by the rotational driving. A two-degree-of-freedom vibration system actuator,
The first mass portion, the second mass portion, the support portion, the first elastic coupling portion, and the second elastic coupling portion are provided in a base body mainly composed of silicon,
A recess is formed on at least one surface of the substrate,
The first mass portion, the second mass portion, the first elastic coupling portion, and the second elastic coupling portion are provided in a portion of the base corresponding to the concave portion. Actuator. The two-degree-of-freedom vibration system includes a pair of the first mass parts,
10. The one of the pair of first mass parts is provided on one end side of the second mass part, and the other is provided on the other end side of the second mass part. Actuator. And the rotational axis of the first mass of the one with respect to the central axis of rotation of the first part by weight one of the, the distance between the substantially vertical direction of the end portion and L _1, L ₂ is a distance between the rotation center axis of the other first mass portion and the end portion of the other first mass portion in a direction substantially perpendicular to the rotation center axis of the other first mass portion; When the distance between the rotation center axis of the second mass part and the end of the second mass part in the direction substantially perpendicular to the rotation center axis is L ₃ , L ₁ and the _{L 3 is,} actuator according to claim 10 satisfies L 1 _{<L 3} the relationship, and the _{L 2} and _{L 3 is,} to satisfy the L 2 _{<L 3} becomes relevant. Wherein the distance L _1, the actuator according to the distance L ₂ and is approximately equal to Claim 11.   The frequency of the AC voltage is set to be substantially equal to a lower one of the resonance frequencies of the two-degree-of-freedom vibration system in which the first mass portion and the second mass portion resonate. The actuator according to any one of claims 12 to 12. When the spring constant of the first elastic connecting portion is k ₁ and the spring constant of the second elastic connecting portion is k ₂ , k ₁ and k ₂ satisfy the relationship of k ₁ > k _2. The actuator according to claim 8.   15. The two-degree-of-freedom vibration system according to claim 8, wherein at least one of the first elastic connecting portion and the second elastic connecting portion includes a piezoresistive element therein. Actuator. The moment of inertia of the first mass and J _1, when the moment of inertia of the second mass was J _2, claims and J ₁ and J ₂ satisfies J ₁ ≦ J ₂ the relationship 8 The actuator according to any one of 15 to 15.

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