JP4793284B2 - Resonance frequency adjusting device and resonance frequency adjusting method - Google Patents

Description

  The present invention relates to a resonance frequency adjusting device and a resonance frequency adjusting method.

For example, an optical scanner for performing drawing by optical scanning with a printer or the like is known that uses an actuator composed of a torsional vibrator. Generally, such a torsional vibrator is composed of a mirror substrate and a torsion beam that supports the mirror substrate.
In such a torsional vibrator, the rotation angle of the mirror substrate is increased by being driven at a frequency equal to the resonance frequency determined by the moment of inertia around the rotation center axis of the mirror substrate and the spring constant of the torsion beam. Can do.

In general, such a torsional vibrator integrally forms a mirror substrate and a torsion beam by etching a silicon substrate. For this reason, depending on the etching accuracy, the moment of inertia around the rotation center axis of the mirror substrate and / or the spring constant of the torsion beam deviates from the target value, and the actual resonance frequency of the torsional vibrator becomes the target resonance frequency. May be off.
Therefore, as a method for correcting such a deviation of the resonance frequency, the surface of the mirror substrate is irradiated with a laser beam, and a part of the mirror substrate is removed, so that the moment of inertia around the rotation center axis of the mirror substrate is reduced. A method is disclosed in which the resonance frequency of the torsional vibrator is reduced to match the target resonance frequency (for example, see Patent Document 1).

  The method of Patent Document 1 is configured to irradiate a laser beam at one place on the plate surface of the mirror. Therefore, depending on the intensity of the laser beam irradiated to the mirror or the irradiation time of the laser beam, a through hole may be formed in the mirror thickness direction, or the intensity of the part irradiated with the laser beam may be different from that of the other part. In some cases, it may be significantly reduced. That is, it may not be possible to provide a vibration system that exhibits excellent scanning characteristics.

JP 2003-84226 A

  An object of the present invention is to provide a resonance frequency adjusting device and a resonance frequency adjusting method capable of efficiently adjusting a resonance frequency and providing a vibration system that exhibits excellent rotation characteristics. is there.

Such an object is achieved by the present invention described below.
The resonance frequency adjusting device of the present invention includes a movable plate and a pair of coupling portions connected to the movable plate, and is configured to rotate the movable plate while twisting and deforming the pair of coupling portions. Measuring means for measuring the resonance frequency of the vibration system ,
A laser beam irradiation means for irradiating a laser beam on the plate surface of the movable plate;
Based on the measurement result of the measuring means, find the combination of the irradiation position of the laser beam on the plate surface of the movable plate, the intensity of the laser beam irradiated to the irradiation position, and the irradiation time of the laser beam, Control means for controlling the operation of the laser light irradiation means to execute laser light irradiation under conditions,
The measuring means is partially irradiated by irradiating the laser beam with a predetermined intensity for a predetermined time at a predetermined position of the movable plate by the laser beam irradiation means and the resonance frequency f _{1 of the} vibration system. And measuring the resonance frequency f _{2 of the} vibration system having the movable plate from which is removed ,
The control means obtains a reduction amount ΔIs of the moment of inertia around the rotation center axis of the movable plate that is reduced by removing the part, and also reduces the reduction amount ΔIs, the resonance frequency f _1, and the resonance frequency. Based on f ₂ , an inertia moment I about the rotation center axis of the movable plate and a torsion spring constant K of the pair of connecting portions are obtained, and further, the reduction amount ΔIs, the inertia moment I, and the torsion are calculated. based on the spring constant K, determined the decrease ΔI of inertia required to match the resonant frequency f ₂ to the resonance frequency f ₀ of the vibration system of the object, on the basis of the obtained the decrease amount ΔI Finding a combination, operating the laser light irradiation means based on the obtained combination,
The laser light is irradiated on the plate surface of the movable plate by the laser beam irradiation means, and a part of the movable plate is removed to reduce the moment of inertia around the rotation center axis of the movable plate, and the vibration The system is configured to adjust the resonance frequency of the system.
Thus, it is possible to adjust the resonance frequency of the very efficiently and accurately vibration system, and to provide a resonance frequency adjusting device capable of providing a vibration system exhibits excellent rotational characteristics it can.

In the resonance frequency adjusting device of the present invention, the control unit is configured to preferentially set a portion distal to the rotation center axis of the movable plate on the plate surface of the movable plate as the irradiation position of the laser beam. It is preferable that
As a result, the weight of the movable plate that must be reduced to adjust the resonance frequency of the vibration system can be reduced, and the resonance frequency of the vibration system can be adjusted extremely efficiently.

In the resonance frequency adjusting apparatus of the present invention, the control means preferentially sets a position close to a line segment passing through the center of gravity of the movable plate and orthogonal to the rotation center axis as the irradiation position of the laser beam. It is preferable that it is comprised.
Thereby, the center of gravity of the movable plate can be kept substantially at the center on the rotation center axis in a plan view of the movable plate. As a result, it is possible to provide the vibration system that can exhibit extremely excellent rotation characteristics.

In the resonance frequency adjusting apparatus of the present invention, it is preferable that an upper limit value is set for each of the intensity and irradiation time of the laser beam irradiated to the irradiation position of the laser beam.
Thereby, it can prevent that the intensity | strength of the said movable plate falls partly remarkably. That is, it is possible to adjust the resonance frequency of the vibration system very accurately while maintaining the mechanical strength of the vibration system.

In the resonance frequency adjusting device of the present invention, a light reflecting portion having light reflectivity is provided on one surface of the movable plate,
It is preferable that the control unit is configured to determine an irradiation position of the laser beam on a surface opposite to the surface on which the light reflecting unit of the movable plate is provided.
Thereby, since the irradiation position of the laser beam can be determined from the entire plate surface on the side where the light reflecting portion of the movable plate is not provided, the resonance frequency of the vibration system in a wide range, And it can adjust correctly. Further, the movable plate can be reduced in size.

In the resonance frequency adjusting device of the present invention, a light reflecting portion having light reflectivity is provided on one surface of the movable plate,
It is preferable that the control unit is configured to determine an irradiation site of the laser light on a surface of the movable plate on which the light reflecting unit is provided.
Usually, the surface of the movable plate on which the light reflecting portion is provided is exposed to the outside in order to perform optical scanning. Therefore, it is possible to adjust the resonance frequency of the vibration system very simply by irradiating the laser beam onto the surface of the movable plate on which the light reflecting portion is provided.

The resonance frequency adjusting method of the present invention includes a movable plate and a pair of coupling portions connected to the movable plate, and is configured to rotate the movable plate while twisting and deforming the pair of coupling portions. A resonance frequency adjustment method for adjusting a resonance frequency of the vibration system by irradiating a laser beam on a plate surface of the movable plate to remove a part of the movable plate,
A first step of measuring a resonance frequency f ₁ of the vibration system;
Based on the measurement result of the first step, a combination of an irradiation position where the laser beam is irradiated on the plate surface of the movable plate, an intensity of the laser beam irradiated to the irradiation position, and an irradiation time of the laser beam A second step for obtaining
And a third step of irradiating the laser beam on the plate surface of the movable plate based on the combination condition obtained in the second step,
In the second step, resonance of the vibration system having the movable plate partially removed by irradiating the laser beam with a predetermined intensity for a predetermined time at a predetermined position of the movable plate. Obtaining a frequency f ₂ and a reduction amount ΔIs of the moment of inertia around the rotation center axis of the movable plate that is reduced by removing the part;
Obtaining an inertia moment I about the rotation center axis of the movable plate and a torsion spring constant K of the pair of connecting portions based on the reduction amount ΔIs, the resonance frequency f ₁ and the resonance frequency f ₂ ; ,
The reduction .DELTA.Is, on the basis of the moment of inertia I and the torsional spring constant K, the resonance frequency f _2, the decrease ΔI of inertia required to match the resonance frequency f ₀ of the vibration system of the object The desired process;
And a step of obtaining the combination based on the obtained reduction amount ΔI .
Thus, it is possible to adjust the resonance frequency of the dynamic system vibration very efficiently, and can provide a vibration system exhibits excellent rotational characteristics.

In the resonance frequency adjusting method of the present invention, in the second step, a portion distal to the rotation center axis of the movable plate on the plate surface of the movable plate is preferentially set as the irradiation position of the laser beam. Is preferred.
As a result, the weight of the movable plate that must be reduced to adjust the resonance frequency of the vibration system can be reduced, and the resonance frequency of the vibration system can be adjusted extremely efficiently.

In the resonance frequency adjusting method of the present invention, in the second step, a position close to a line segment passing through the center of gravity of the movable plate and orthogonal to the rotation center axis is preferentially set as the irradiation position of the laser beam. It is preferable to do.
Thereby, the center of gravity of the movable plate can be kept substantially at the center on the rotation center axis in a plan view of the movable plate. As a result, it is possible to provide the vibration system that can exhibit extremely excellent rotation characteristics.

In the resonance frequency adjusting method of the present invention, it is preferable that an upper limit value is set for each of the intensity and irradiation time of the laser beam irradiated to the irradiation position of the laser beam.
Thereby, it can prevent that the mechanical strength of the said movable plate falls partly remarkably. That is, it is possible to adjust the resonance frequency of the vibration system very accurately while maintaining the mechanical strength of the vibration system.

DESCRIPTION OF EXEMPLARY EMBODIMENTS Hereinafter, preferred embodiments of a resonance frequency adjusting device and a resonance frequency adjusting method of the invention will be described with reference to the accompanying drawings.
<First Embodiment>
First, a first embodiment of the resonance frequency adjusting device of the present invention will be described.
FIG. 1 is a perspective view showing a first embodiment of the resonance frequency adjusting device of the present invention, FIG. 2 is a partial cross-sectional perspective view showing an actuator in which the resonance frequency is adjusted by the resonance frequency adjusting device shown in FIG. 3 is a diagram showing an example of an AC voltage applied to the actuator shown in FIG. 2, FIG. 4 is a block diagram showing a measuring device provided in the resonance frequency adjusting device shown in FIG. 1, and FIG. 5 is a diagram of a movable plate provided in the actuator. FIG. 6 is a flowchart showing the operation of the resonance frequency adjusting device shown in FIG. 1, and FIG. 7 is a flowchart showing a subroutine of S2 shown in FIG.
In the following, for convenience of explanation, the axes orthogonal to each other as shown in FIG. 1 are referred to as “X-axis”, “Y-axis”, and “Z-axis”, respectively, and the direction parallel to the X-axis is referred to as “X-axis direction”. The direction parallel to the Y axis is referred to as “Y axis direction”, and the direction parallel to the Z axis is referred to as “Z axis direction”.

  As shown in FIG. 1, the resonance frequency adjusting device 1 includes a stage 5 that fixes the actuator 6, a moving device 7 that moves the stage 5, and a measuring device that measures the resonance frequency of the vibration system 60 included in the actuator 6 (measurement). Means) 2, a laser light irradiation device (laser light irradiation means) 4 for irradiating laser light onto the plate surface of the movable plate 611 provided in the actuator 6, and the laser light irradiation device 4 based on the measurement result of the measurement device 2. And a control section (control means) 3 for controlling the operation of the apparatus.

First, the actuator 6 whose resonance frequency is adjusted by the resonance frequency adjusting device 1 will be briefly described. In the following, for convenience of explanation, the front side of the paper in FIG. 2 is referred to as “up” and the back side of the paper is referred to as “down”.
As shown in FIG. 2, the actuator 6 includes a base 61 having a vibration system 60, a support substrate 62 that supports the base 61 via a bonding layer 63, and a counter substrate 64 that is bonded to the lower surface of the support substrate 62. And a pair of fixed electrodes 651 and 652 provided on the upper surface of the counter substrate 64.

The base 61 includes a movable plate 611, a support portion 612 for supporting the movable plate 611, and a pair of connecting portions 613 and 614 that connect the movable plate 611 and the support portion 612.
On the upper surface of the movable plate 611, a light reflecting portion 611a having light reflectivity is provided. Thereby, the actuator 6 can be used for MEMS application sensors such as an acceleration sensor and an angular velocity sensor, and optical devices such as an optical scanner, an optical switch, and an optical attenuator.

Note that a laser light absorption layer for increasing the absorption efficiency of the laser light irradiated from the laser light irradiation device 4 (that is, for preventing reflection of the laser light) is formed on the plate surface of the movable plate 611. It may be. Such a laser light absorbing layer includes, for example, a colored layer, although it varies depending on the type of laser light. Further, a removal layer mainly composed of carbon black, titanium powder, mica, or the like may be formed on the plate surface of the movable plate 611 so that a part of the movable plate 611 can be easily removed by laser light. Thereby, the resonance frequency adjusting device 1 can remove a part of the movable plate 611 extremely efficiently.
Such a movable plate 611 is supported by the support portion 612 via a pair of connecting portions 613 and 614.

Each of the pair of connecting portions 613 and 614 has a longitudinal shape and can be elastically deformed. Each of the connecting portions 613 and 614 connects the movable plate 611 and the support portion 612 so that the movable plate 611 can be rotated with respect to the support portion 612. Connecting portions 613, 614 of such a pair are provided coaxially, the shaft as a rotation center axis X _1, is configured such that the movable plate 611 is pivoted relative to the support portion 612 Yes.
The support portion 612 that supports the movable plate 611 via the pair of connection portions 613 and 614 has a frame shape and is provided so as to surround the outer periphery of the movable plate 611 in a plan view of the movable plate 611. ing.

The base 61 as described above is made of, for example, silicon as a main material, and a movable plate 611, a support portion 612, and a pair of connecting portions 613 and 614 are integrally formed.
The base 61 as described above is bonded to the support substrate 62 via the bonding layer 63.
Such a support substrate 62 is made of, for example, glass or silicon as a main material. The support substrate 62 has a frame shape and has substantially the same shape as the support portion 612 in plan view of the movable plate 611.

The bonding layer 63 formed between the support substrate 62 and the base body 61 is made of, for example, glass, silicon, or SiO ₂ as a main material.
A counter substrate 64 is bonded to the lower surface of the support substrate 62. The counter substrate 64 has a plate shape, and a pair of fixed electrodes 651 and 652 for rotating the movable plate 611 is provided on the upper surface thereof.
The pair of fixed electrodes 651 and 652 are provided on the upper surface of the counter substrate 64 so as to correspond to the movable plate 611 in plan view of the movable plate 611. The fixed electrode 651 and 652 of the pair in the plan view of the movable plate 611, so as to be spaced apart from each other through the rotation center axis _{X 1,} and symmetrical with respect to the rotation center axis _{X 1} It is provided as follows.

Such an actuator 6 is driven as follows.
First, the base 61 is grounded. Then, for example, a voltage as shown in FIG. 3A is applied to the fixed electrode 651 and a voltage as shown in FIG. 3B is applied to the fixed electrode 652. That is, the state where the voltage is applied only to the fixed electrode 651 and the state where the voltage is alternately applied only to the fixed electrode 652 are alternately repeated. Thereby, a state where an electrostatic attractive force (Coulomb force) is generated between the movable plate 611 and the fixed electrode 651, and a state where an electrostatic attractive force is generated between the movable plate 611 and the fixed electrode 652; Can be repeated alternately. As a result, it is possible to rotate the respective connecting portions 613, 614 of the pair of movable plate 611 by torsional deformation around the rotation center axis X _1. From this, it can be said that the vibration system 60 is constituted by the movable plate 611 and the pair of connecting portions 613 and 614.
Here, by making the frequency of the voltage applied to each of the pair of fixed electrodes 651 and 652 coincide with the resonance frequency of the vibration system 60, the movable plate 611 can be largely rotated.

The actuator 6 has been described above. Hereinafter, the resonance frequency adjusting device 1 for adjusting the resonance frequency of the vibration system 60 provided in the actuator 6 will be described in detail. As described above, the resonance frequency adjusting device 1 includes the stage 5 that fixes the actuator 6, the moving device 7 that moves the stage 5, the measuring device 2 that measures the resonance frequency of the vibration system 60, and the plate of the movable plate 611. A laser light irradiation device 4 that irradiates the surface with laser light and a control unit 3 that controls the operation of the laser light irradiation device 4 based on the measurement result of the measurement device 2 are provided.
Such a resonance frequency adjusting device 1 irradiates a laser beam on the plate surface of the movable plate 611, thereby removing (for example, evaporating) a part of the movable plate 611, thereby rotating the movable plate 611. reducing the moment of inertia around the central axis X _1, it is configured to adjust the resonance frequency of the vibration system 60.

The moving device 7 is a device for moving the stage 5 in the X-axis direction in FIG. As shown in FIG. 1, the moving device 7 is connected to the control unit 3, and its operation is controlled by the control unit 3.
In the middle of the moving direction of the moving device 7, there are provided a measuring device 2 for measuring the resonance frequency of the vibration system 60 and a laser beam irradiation device 4 for irradiating the plate surface of the movable plate 611 with a laser beam. It has been. That is, the resonance frequency adjusting device 1 operates the moving device 7 with the actuator 6 fixed on the stage 5, measures the resonance frequency of the vibration system 60 with the measuring device 2, and moves the movable plate 611 with the laser light irradiation device 4. It is comprised so that a laser beam may be irradiated on the plate surface.
A stage 5 is provided on such a moving device 7. As shown in FIG. 1, the stage 5 includes a base 51 fixed to the moving device 7 and a turntable 52 that can rotate with respect to the base 51.

  The turntable 52 is provided so as to face the upper surface of the base 51. The turntable 52 can rotate around the Z axis with respect to the base 51. Such a rotating disk 52 is connected to the control means 3, and its operation (rotational motion) is controlled by the control means 3. Further, the upper surface of the turntable 52 forms a surface parallel to the XY plane, and the actuator 6 is fixed on this surface. Here, when the actuator 6 is fixed to the turntable 52, the actuator 6 is set in a state in which the actuator 6 can be rotationally driven.

  The measuring device 2 measures the resonance frequency of the vibration system 60 of the actuator 6 fixed on the stage 5. As shown in FIG. 4, such a measuring apparatus 2 has a laser beam Doppler velocity (hereinafter simply referred to as “LDV”) 21 that measures the amplitude (that is, the rotation angle (deflection angle)) of the movable plate 611 of the actuator 6. And an FFT analyzer 22 that changes (sets) the frequency of the AC voltage applied to the fixed electrodes 651 and 652 of the actuator 6.

  As a method for measuring the resonance frequency of the vibration system 60, first, the frequency of the AC voltage applied to the fixed electrodes 651 and 652 is set to a predetermined value (for example, 1 Hz) by the FFT analyzer 22, and the AC voltage is set to the fixed electrode 651. , 652 to drive the actuator 6. Then, the LDV 21 irradiates the movable plate 611 (light reflecting portion 611a) with laser light, receives the reflected light, and measures the rotation angle of the movable plate 611. In this case, the amplitude of the movable plate 611 is actually measured by the LDV 21.

Next, the frequency of the AC voltage applied to the fixed electrodes 651 and 652 is changed to a predetermined high value by the FFT analyzer 22, the actuator 6 is driven at that frequency, and the rotation angle of the movable plate 611 is changed by the LDV 21. taking measurement.
Then, the rotation angle of the movable plate 611 is repeatedly measured until the frequency of the AC voltage applied to the fixed electrodes 651 and 652 reaches a predetermined value (for example, 32 KHz). From this measurement result, the resonance frequency of the vibration system 60 is obtained.

  Data of the resonance frequency of the vibration system 60 obtained by the measuring device 2 is sent to the control unit 3 and stored. And the control part 3 is the laser beam irradiation position where the resonance frequency of the vibration system 60 corresponds with the target resonance frequency, the intensity | strength of the laser beam irradiated to the irradiation position, and the irradiation time of a laser beam. Find a combination. Further, the control unit 3 controls the operation of the laser light irradiation device 4 so as to execute laser light irradiation under the conditions (combination).

The laser beam irradiation device 4 is connected to the control unit 3 and its operation is controlled by the control unit 3. As shown in FIG. 1, the laser light irradiation device 4 includes a laser light irradiation unit 41 that irradiates laser light in the Z-axis direction and a position control device 42 that controls the position of the laser light irradiation unit 41. Yes.
Such a laser beam irradiation device 4 is configured to irradiate the laser beam onto the upper surface of the movable plate 611 of the actuator 6 (the surface on which the light reflecting portion 611a is provided). Since the upper surface of the movable plate 611 is exposed to the outside, the movable plate 611 can be irradiated with laser light very easily.

  The operation of the laser beam irradiation unit 41 is controlled by the control unit 3 so that the intensity of the irradiated laser beam is constant. That is, if the irradiation time of the laser beam on the plate surface of the movable plate 611 is equal, the weight removed from the movable plate 611 is also equal. Note that the correlation between the laser beam irradiation time and the weight of the movable plate 611 decreased thereby is previously stored in the control unit 3 as data by measurement or the like.

An upper limit is set for the intensity of the laser irradiated from the laser beam irradiation unit 41. Such an upper limit value is preferably set in consideration of the shape (size, thickness) of the movable plate 611, the type of laser light, and the like. As described above, by determining the upper limit value of the intensity of the laser beam, it is possible to prevent the intensity of the movable plate 611 from being significantly reduced. That is, the resonance frequency of the vibration system 60 can be adjusted very accurately while maintaining the mechanical strength of the vibration system 60.
Further, in the present embodiment, the intensity of the laser irradiated from the laser light irradiation unit 41 is kept constant at an intensity equal to or less than the upper limit value.

The laser light emitted from the laser light irradiation unit 41 is not particularly limited as long as a part of the movable plate 611 can be removed. For example, laser light such as CO ₂ , YAG, and excimer is preferably used. be able to. Further, as described above, when the removal layer is formed on the plate surface of the movable plate 611, it is possible to use a laser beam such as a semiconductor laser although it depends on the type of the laser beam.

The position control device 42 moves the laser light irradiation unit 41 along the Y-axis direction and the Z-axis direction according to a signal from the control unit 3. Further, the position control device 42 rotates the laser light irradiation unit 41 around the Z axis according to a signal from the control unit 3.
Here, the stage 5 to which the actuator 6 is fixed can be moved in the X-axis direction by the moving device 7 as described above, and the rotating disk 52 can be rotated around the Z-axis. Therefore, by using the laser beam irradiation device 4 and the stage 5, the relative positional relationship between the laser beam irradiation unit 41 and the movable plate 611 can be freely changed, and the laser beam can be transmitted on the movable plate 611 extremely accurately. The irradiation position can be irradiated.
The configuration of the resonance frequency adjusting device 1 has been described above.

Next, a method for adjusting the resonance frequency of the vibration system 60 (that is, the operation of the resonance frequency adjusting device 1) will be described with reference to FIGS. Hereinafter, for convenience of explanation, the position of the stage 5 when the actuator 6 is fixed to the stage 5 is referred to as a “first position”, and the position of the stage 5 when the resonance frequency of the vibration system 60 is measured by the measuring device 2. Is the “second position”, and the position of the stage 5 when the laser light irradiation device 4 irradiates the laser beam onto the plate surface of the movable plate 611 is the “third position”. Further, the target resonance frequency of the vibration system 60 is “f ₀ ”.

  As shown in FIG. 6, such a resonance frequency adjusting method includes a step (S1) of measuring the resonance frequency of the vibration system 60 and a laser beam on the plate surface of the movable plate 611 based on the measurement result of S1. The step (S2) for obtaining a combination of the irradiation position to be irradiated, the intensity of the laser beam irradiated to the irradiation position, and the irradiation time of the laser beam, and the laser beam irradiation are executed under the condition (combination) determined in S2. Step (S3).

First, the moving device 7 is operated to move the stage 5 to the first position. Then, the actuator 6 is fixed on the turntable 52 of the stage 5 and the actuator 6 is brought into a state in which the actuator 6 can be rotated. The actuator 6 is prefabricated to be slightly lower (design) with respect to the resonance frequency f ₀ the resonance frequency is the purpose of the vibration system 60.
Then, the moving device 7 is operated to move the stage 5 to the second position. Then, the measurement device 2 measures the resonance frequency of the vibration system 60 (hereinafter, this resonance frequency is referred to as “f ₁ ”). Since the measurement method is as described above, the description thereof is omitted. Data of the resonance frequency f ₁ of the vibration system 60 measured by the measuring device 2 is sent to the control unit 3 and stored.

  Next, the moving device 7 is operated to move the stage 5 to the third position. Then, the laser beam irradiation device 4 is operated by the control unit 3 to irradiate the laser beam to a predetermined position on the plate surface of the movable plate 611 for a predetermined time, and remove a part of the movable plate 611. (S201). As described above, since the phase difference between the laser beam irradiation time and the weight of the movable plate 611 decreased thereby is accumulated in the control unit 3, it is removed from the movable plate 611 based on the laser beam irradiation time. The calculated weight can be calculated.

Thus, the predetermined position on the plate surface of the movable plate 611, by irradiating only a laser beam a predetermined time, it by moment of inertia around the rotation center axis X ₁ of the movable plate 611 A reduction amount (hereinafter, this reduction amount is referred to as “ΔI _S ”) can be calculated. Specifically, when the distance between the laser beam irradiation position rotational axis X ₁ and R (m), reduced the weight of the movable plate 611 and the M (kg), ΔI _S is shown below It is calculated | required by Formula (1).
ΔI _S = M × R ² (kg · m ² ) (1)

Next, the moving device 7 is operated to move the stage 5 again to the second position. Then, the measurement apparatus 2 measures the resonance frequency of the vibration system 60 in a state where a part of the movable plate 611 is removed (hereinafter, this resonance frequency is referred to as “f ₂ ”) (S202). Data of measured resonance frequency f ₂ is stored is transmitted to the control unit 3.
At this time, the control unit 3 accumulates data of the resonance frequency f ₀ , the resonance frequency f _1, and the resonance frequency f ₂ . Then, the control unit 3 uses the resonance frequency f ₁ and the resonance frequency f ₂ from the data of the three resonance frequencies f ₀ , f ₁ , and f ₂ to rotate the movable plate 611 that constitutes the vibration system 60. An inertia moment about the axis X ₁ (hereinafter, this inertia moment is referred to as “I”) and a torsion spring constant (hereinafter, this spring constant is referred to as “K”) of the pair of connecting portions 613 and 614 are obtained ( S203). Specifically, the value of the resonance frequency f ₁ is substituted into the following formula (2), and similarly, the value of the resonance frequency f _{2 and} the value of ΔI _S are substituted into the following formula (3). As a result, the moment of inertia I and the spring constant K can be obtained.
f ₁ = 1 / 2π√ (k / I) (2)
f ₂ = 1 / 2π√ {k / (I−ΔI _S )} (3)

Thus, after determining the moment of inertia I and the spring constant K, decrease in moment of inertia around the rotation center axis X ₁ of the movable plate 611 required to match the resonant frequency f ₂ to the resonance frequency f ₀ The amount ΔI is calculated (S204). More specifically, the equation (4) below, to calculate the value of the resonance frequency f _0, the value of the spring constant K, the [Delta] I by substituting the value of [Delta] I _S.
f ₀ = 1 / 2π√ {k / (I−ΔI _S −ΔI)} (4)

Next, the control means 3 determines, based on the calculated ΔI, the irradiation position of the laser beam on the plate surface of the movable plate 611, the intensity of the laser beam irradiated to the irradiation position, and the irradiation time of the laser beam. Find a combination. Hereinafter, a method for obtaining a combination of the irradiation position of the laser beam, the intensity of the laser beam, and the irradiation time of the laser beam will be described. It is assumed that the sum of reduction amounts ΔI _A , ΔI _B , and ΔI _C of inertia moment, which will be described later, is greater than or equal to ΔI. That is, the relationship of ΔI ≦ ΔI _A + ΔI _B + ΔI _C is satisfied. In the present embodiment, as described above, the intensity of the laser light is kept constant by the control unit 3.

As shown in FIG. 6, on the plate surface (upper surface) of the movable plate 611, a plurality of laser light irradiable positions P _{1 to} P ₃₀ provided at different positions are defined. The distances between the laser beam irradiable positions P _{1 to} P ₃₀ and the rotation center axis X ₁ are stored as data in the control unit 3. Further, the laser beam irradiable positions P _{1 to} P ₃₀ are not defined on the light reflecting portion 611a. In the present embodiment, a total of 30 possible laser beam irradiation positions are determined.
Such laser beam irradiable positions P _{1 to} P ₃₀ are orthogonal to the rotation center axis X ₁ in plan view of the plurality of line segments L _{1 to} L ₆ parallel to the rotation center axis X ₁ and the movable plate 611. It is located on the intersection with a plurality of line segments L7 to L11.

In line L1 to L6, the line segment L1 and the line segment L2, the line L3 and the line segment L4, each of the line segments L5 and the line segment L6, are symmetrical with respect to the rotational axis _{X 1.}
Line L7 is in plan view of the movable plate 611, passes through the center of gravity of the movable plate 611, a line segment which is perpendicular to the rotational axis X _1. The line segment L8 and the line segment L9, and the line segment L10 and the line segment L11 are symmetric with respect to the line segment L7.
In addition, an upper limit is set for the irradiation time of the laser beam to each of the laser beam irradiation possible positions P _{1 to} P ₃₀ . Such upper limit values are set to be equal to each other with respect to the laser beam irradiable positions P _{1 to} P ₃₀ .

That is, the control unit 3, the distance from the pivoting central axis _{X 1} of the laser beam can be irradiated position _P 1 _{to P 30,} the maximum irradiation time of the laser light to the laser beams can be irradiated position _P 1 _{to P 30} (That is, the maximum weight that can be removed from each of the laser beam irradiable positions P _{1 to} P ₃₀ ). Therefore, any laser light irradiation possible position among the laser light irradiation possible positions P _{1 to} P ₃₀ is irradiated with laser light having a predetermined intensity for how long, and thereby the movable plate 611 is rotated. reduction of the inertia moment about the central axis X ₁ can be obtained either a very simply equal to [Delta] I.
Specifically, the control unit 3 first sets the upper limit value to each of the laser beam irradiable positions P _{1 to} P ₅ on the line segment L1 and the laser beam irradiable positions P _{6 to} P ₁₀ on the line segment L2. If when irradiated with equal time laser light, decrease in the moment of inertia around the rotation center axis X ₁ of the movable plate 611 (hereinafter, this reduction amounts to a "[Delta] I _a") and is compared with the [Delta] I ( S205).

[Delta] I is smaller than [Delta] I _A, the control unit 3 determines the irradiation time of the laser beam to be irradiated on the laser beam can be irradiated position P ₁ to P _10. That is, how long the laser beam is irradiated onto the laser beam irradiable positions P _{1 to} P ₁₀ to determine how much the moment of inertia around the rotation center axis X ₁ of the movable plate 611 that is decreased is equal to ΔI. Ask. Then, based on the obtained irradiation time, the laser light irradiation position is selected from the laser light irradiation possible positions P _{1 to} P ₁₀ and the irradiation time of the laser light to be irradiated to the selected irradiation position is determined (S206). ).

At this time, the control unit 3, so that the number of the irradiation position to be selected is the smallest, selecting the irradiation position of the laser beam from the laser beam can be irradiated position P ₁ to P _10. For example, the upper limit value of the irradiation time of the laser beam to each of the laser beam irradiable positions P _{1 to} P ₁₀ is 1.0 (seconds), and a total of 3.6 (on the laser beam irradiable positions P _{1 to} P ₁₀ ( s) when the laser beam must be irradiated selects from the laser beam can be irradiated position P ₁ to P ₁₀ 4 single irradiation position. Then, for example, (1) laser light irradiation time to three irradiation positions of the selected four laser light irradiation positions is set to an upper limit of 1.0 (seconds), and the remaining one irradiation position is irradiated with laser light. The time is set to 0.6 (seconds), or (2) the laser beam irradiation time to each of the selected four irradiation positions is set to 0.9 (seconds). Thereby, the operation time of the laser beam irradiation apparatus 4 can be shortened, and the resonance frequency of the vibration system 60 can be adjusted efficiently.

The control unit 3, so that a possible symmetrical with respect to the rotational axis X _1, selects the irradiation position of the laser beam from the laser beam can be irradiated position P ₁ to P _10. Thus, while keeping the center of gravity of the movable plate 611 on the rotational axis X _1, it is possible to adjust the resonance frequency of the vibration system 60. That is, it is possible to provide the actuator 6 having extremely excellent rotation characteristics.
The control unit 3, in the laser beam can be irradiated position _P 1 to P ₅ on the line segment L1, passes through the center of gravity of the movable plate 611 and perpendicular to the rotational axis _{X 1} segment (i.e., segment L7) is preferentially selected as the laser beam irradiation position from the side closer to L7). Specifically, the control unit 3 first selects the laser beam irradiable position P ₁ as the irradiation position, then selects either P ₂ or P ₃ as the irradiation position, and then selects P ₂ or P 3. The other of ₃ is selected as the irradiation position, then either P ₄ or P ₅ is selected as the irradiation position, and finally the other of P ₄ or P ₅ is selected as the irradiation position. Thus, it is possible to maintain in the plan view of the movable plate 611, the center of gravity of the movable plate 611 at substantially the center on the rotational axis X _1. As a result, it is possible to provide the actuator 6 having extremely excellent rotation characteristics. Since the laser beam irradiable positions P _{6 to} P ₁₀ are the same as the laser beam irradiable positions P _{1 to} P ₅ , description thereof is omitted.

On the other hand, if [Delta] I is greater than [Delta] I _A, the control unit 3, the laser along with selecting all of the laser beam can be irradiated position P ₁ to P ₁₀ as the irradiation position of the laser beam, to all irradiation positions selected The light irradiation time is set as the upper limit (S207).
Then, the respective laser beams can be irradiated position _P 16 _{to P 20} on the laser beam can be irradiated position on the line segment L3 _P 11 _{to P 15} and the line segment L4, in a case of radiating the upper limit time equal laser beam reduction of the moment of inertia around the rotation center axis _{X 1} of the movable plate 611 (hereinafter, this increment is referred to as "[Delta] I _B") and comparing the _{(ΔI-ΔI a) (S208} ).

When (ΔI-ΔI _A) is less than [Delta] I _B, the control unit 3 determines the irradiation time of the laser beam to be irradiated on the laser beam can be irradiated position _P 11 _{to P 20.} That is, if the laser beam is irradiated onto the laser beam irradiable positions P _{11 to} P ₂₀ for how long, the moment of inertia around the rotation center axis X ₁ of the movable plate 611 is reduced by (ΔI−ΔI _A ). Is equal to Then, based on the results obtained, as well as selecting the irradiation position of the laser beam from the laser beam can be irradiated position P ₁₁ to P _20, it determines the laser beam irradiation time to the selected irradiation position (S209). Since the means for selecting the irradiation position from the laser beam irradiable positions P _{11 to} P ₂₀ is the same as the means for selecting the irradiation position from the laser beam irradiable positions P _{1 to} P ₁₀ , description thereof is omitted.

On the other hand, if (ΔI-ΔI _A) is larger than [Delta] I _B, the control unit 3 is configured to select all of the laser beam can be irradiated position P ₁₁ to P ₂₀ as the irradiation position of the laser beam, all of the selected The laser beam irradiation time to the irradiation position is set as the upper limit (S210).
Here, when the laser beam irradiable positions P _{21 to} P ₂₅ on the line segment L5 and the laser beam irradiable positions P _{26 to} P _{30 on} the line segment L6 are irradiated with the laser beam for a time equal to the upper limit value, respectively. reduction of the moment of inertia around the rotation center axis _{X 1} of the movable plate 611 (hereinafter, this reduction amounts to a "[Delta] I _C") is larger than _{{ΔI- (ΔI a + ΔI B} )}.

Therefore, the control unit 3 obtains the irradiation time of the laser light to be irradiated on the laser light irradiable positions P _{21 to} P ₃₀ . That is, if the laser beam is irradiated onto the laser beam irradiable positions P _{21 to} P ₃₀ for how long, the moment of inertia around the rotation center axis X ₁ of the movable plate 611 is reduced by {ΔI− (ΔI _A + ΔI _B )}. Then, based on the results obtained, as well as selecting the irradiation position of the laser beam from the laser beam can be irradiated position P ₂₁ to P _30, it determines the laser beam irradiation time to the selected irradiation position (S211). Since the means for selecting the irradiation position from the laser beam irradiable positions P _{21 to} P ₃₀ is the same as the means for selecting the irradiation position from the laser beam irradiable positions P _{1 to} P ₁₀ , description thereof is omitted.
In this way, the control unit 3 obtains a combination of the irradiation position where the laser beam is irradiated, the intensity of the laser beam irradiated to the irradiation position, and the irradiation time of the laser beam.

From the above, the control unit 3, in the laser beam can be irradiated position P ₁ to P _30, the laser beam can be irradiated position located distal to the rotational axis X ₁ as the irradiation position of preferentially laser beam Configured to select. As a result, it is possible to reduce the irradiation time of the laser beam that has to be irradiated in order to make the resonance frequency of the vibration system 60 coincide with the target resonance frequency f ₀ , and to resonate the vibration system 60 extremely efficiently and economically. The frequency can be adjusted.
Then, the laser beam irradiation device 4 is operated so as to execute the laser beam irradiation under the conditions (combination) determined as described above, and a part of the movable plate 611 is removed (S3).
As described above, the resonance frequency adjusting device 1 adjusts the resonance frequency of the vibration system 60.

By using such a resonance frequency adjusting device 1 (that is, a resonance frequency adjusting method), it is possible to adjust the resonance frequency of the vibration system 60 very efficiently and to exhibit excellent rotation characteristics. A system 60 (actuator 6) can be provided.
Further, as described above, an upper limit value is set for the laser beam irradiation time to each of the laser beam irradiation possible positions P _{1 to} P ₃₀ . Thereby, for example, a through-hole is formed in the thickness direction of the movable plate 611, or the mechanical strength of the position where the laser beam is irradiated on the movable plate 611 is remarkably reduced compared to that at other positions. Can be prevented. That is, the resonance frequency of the vibration system 60 can be adjusted very accurately while maintaining the mechanical strength of the vibration system 60 (actuator 6).

Further, in this embodiment, 30 laser beam irradiation possible positions are determined, but if the resonance frequency of the vibration system 60 can be adjusted to the target resonance frequency f ₀ , the number of laser beam irradiation possible positions is: There is no particular limitation. The number of laser light irradiation possible positions is (1) after taking into account the upper limit of the laser light irradiation time to each irradiation position, (2) the resonance frequency shift in the manufacturing stage of the actuator 6 that is expected in advance. The resonance frequency of the vibration system 60 is preferably set to a number that can be adjusted to the target resonance frequency with a margin.

Further, in this embodiment, keeping the intensity of the laser light constant, by controlling the time for irradiating the laser beam, for those that control the amount of decrease in the moment of inertia around the rotation center axis X ₁ of the movable plate 611 the described but, if it is possible to control the decrease of the moment of inertia around the rotation center axis X ₁ of the movable plate 611. not limited thereto.
For example, the control unit 3 maintains the laser beam irradiation time for one time, and changes the intensity of the laser beam irradiated from the laser beam irradiation unit 41 within a certain range. It may be configured to control the operation of 41. Note that the phase difference between the intensity of the laser beam and the decrease in the weight of the movable plate 611 when the laser beam is irradiated once is stored in advance in the control unit 3 as data by measurement or the like. Thus, by changing the intensity of the laser light, the time for irradiating the movable plate 611 with the laser light can be shortened.
In this case, for example, the laser light irradiable positions P _{1 to} P ₃₀ on the plate surface of the movable plate 611 can be irradiated only once, and further, each laser light irradiable position P _1. the intensity of the laser beam irradiated to the to P _30, the upper limit is defined.

The control unit 3, the distance from the pivoting central axis X ₁ of the laser beam can be irradiated position P ₁ to P _30, the maximum intensity of the laser beam applied to the laser beams can be irradiated position P ₁ to P ₃₀ Data is accumulated. Therefore, if the laser beam of which intensity is irradiated once to any of the laser beam irradiable positions P _{1 to} P ₃₀ , the rotation center axis X ₁ of the movable plate 611 is thereby irradiated. It can be very easily determined whether the amount of decrease in the surrounding moment of inertia is equal to ΔI. Therefore, the resonance frequency of the vibration system 60 can be adjusted very accurately also by such a control method of the control unit 3.

Second Embodiment
Next, a third embodiment of the resonance frequency adjusting device of the present invention will be described.
FIG. 8 is a perspective view showing a second embodiment of the resonance frequency adjusting device of the present invention, and FIG. 9 is a rear view of a movable plate provided in an actuator whose resonance frequency is adjusted by the resonance frequency adjusting device shown in FIG. is there. For convenience of explanation, the front side of the paper surface in FIG. 8 is referred to as “upper”, and the rear side of the paper surface is referred to as “lower”.
Hereinafter, the resonance frequency adjustment device 1A of the second embodiment will be described focusing on the differences from the resonance frequency adjustment device 1 of the first embodiment described above, and description of similar matters will be omitted.

The resonance frequency adjusting device 1A according to the second embodiment of the present invention is configured to irradiate a laser beam onto the back surface of the movable plate 611 (the surface opposite to the surface on which the light reflecting portion is provided). Except for this, it is substantially the same as the resonance frequency adjusting apparatus 1 of the first embodiment. The same reference numerals are given to the same components as those in the first embodiment described above.
As shown in FIG. 8, the resonance frequency adjusting device 1A has the same configuration as the resonance frequency adjusting device 1 of the first embodiment except that the configuration of the stage 5A is different.

The stage 5 </ b> A includes a base 51 provided on the moving unit 5, a rotating plate 52 that can rotate about the Z axis with respect to the base 51, and a fixing member 53 </ b> A provided on the rotating plate 52. Yes.
The fixing member 53A is a member for supporting the base body 61. Here, when the base 61 is fixed, the base 61 is fixed so that the back surface of the movable plate 611 faces upward in FIG. 8, that is, the back surface of the movable plate 611 faces the laser light irradiation unit 41. To do. Thereby, the laser beam can be easily applied to the back surface of the movable plate 611.
The fixing member 53A is provided with a driving means (not shown) for driving the vibration system 60 provided in the base body 61. Since the base 61 fixed to the fixing member 53A is not provided with driving means such as a fixed electrode for driving the vibration system 60, vibration is generated on the stage 5 by providing the fixing means 53A with driving means. The system 60 can be driven to rotate.

  As shown in FIG. 9, a plurality of laser beam irradiable positions P are defined over the entire back surface of the movable plate 611. Therefore, the resonance frequency of the vibration system 60 can be accurately adjusted over a wide range. Further, the movable plate 611 can be reduced in size as compared with the case where the surface of the movable plate 611 provided with the light reflecting portion 611a is irradiated with laser light (that is, the first embodiment).

In the present embodiment, the base body 61 is bonded to the support substrate 62 via the bonding layer 63 after the resonance frequency is adjusted by the resonance frequency adjusting device 1A. Furthermore, the actuator 6 is manufactured by bonding to the counter substrate 64 provided with the fixed electrodes 651 and 652.
However, depending on the shape of the actuator 6 and the like, the resonance frequency of the vibration system 60 may be adjusted by the resonance frequency adjusting device 1A after the actuator 6 is manufactured.
Also by such 2nd Embodiment, the effect similar to 1st Embodiment can be exhibited.

The resonance frequency adjusting device and the resonance frequency adjusting method of the present invention have been described based on the illustrated embodiment, but the present invention is not limited to this. For example, in the resonance frequency adjusting device of the present invention, the configuration of each part can be replaced with any configuration that exhibits the same function, and any configuration can be added.
In the above-described embodiment, the laser beam irradiation possible position has been described on the intersection of a plurality of line segments parallel to each other and a plurality of line segments orthogonal to the line segments. The possible position is not limited to this. For example, a plurality of laser beam irradiating positions may be defined without regularity on the plate surface of the movable plate.

It is a perspective view which shows 1st Embodiment of the resonant frequency adjustment apparatus of this invention. It is a fragmentary sectional perspective view which shows the actuator by which the resonance frequency is adjusted with the resonance frequency adjustment apparatus shown in FIG. It is a figure which shows an example of the alternating voltage applied to the actuator shown in FIG. It is a block diagram explaining the measuring apparatus with which the resonant frequency adjustment apparatus shown in FIG. 1 is provided. It is a top view of the movable plate with which the actuator shown in FIG. 2 is provided. It is a flowchart which shows the action | operation of the resonant frequency adjustment apparatus shown in FIG. It is a flowchart which shows the subroutine of S2 shown in FIG. It is a perspective view which shows 2nd Embodiment of the resonant frequency adjustment apparatus of this invention. FIG. 9 is a bottom view of a movable plate provided in an actuator whose resonance frequency is adjusted by the resonance frequency adjusting device shown in FIG. 8.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1, 1A ... Resonance frequency adjusting device 2 ... Measuring device (measuring means) 21 ... Laser light Doppler velocity (LDV) 22 ... FFT analyzer 3 ... Control part (control means) 4 ... ...... Laser beam irradiator (Laser beam irradiator) 41 ............ Laser beam irradiator 42 ...... Position controller 5, 5A ...... Stage 51 ............ Base 52 ............ Turntable 53A ............ Fixed Components 6 ... Actuator 60 ... Vibration system 61 ... Base body 611 ... Movable plate 611a ... Light reflection part 612 ... Support parts 613, 614 ... Connection part 62 ... Support board 63 ... Junction layer 64 ... Counter substrate 651, 652 ... Fixed electrode 7 ... Movement device P, P _{1 to} P ₃₀ ... Laser beam irradiable position X, Y, Z ... axis X ₁ ............ Rotation center axis

Claims (10)

Measuring a resonance frequency of a vibration system having a movable plate and a pair of connecting portions connected to the movable plate and configured to rotate the movable plate while twisting and deforming the pair of connecting portions. Measuring means;
A laser beam irradiation means for irradiating a laser beam on the plate surface of the movable plate;
Based on the measurement result of the measuring means, find the combination of the irradiation position of the laser beam on the plate surface of the movable plate, the intensity of the laser beam irradiated to the irradiation position, and the irradiation time of the laser beam, Control means for controlling the operation of the laser light irradiation means to execute laser light irradiation under conditions,
The measuring means is partially irradiated by irradiating the laser beam with a predetermined intensity for a predetermined time at a predetermined position of the movable plate by the laser beam irradiation means and the resonance frequency f _{1 of the} vibration system. And measuring the resonance frequency f _{2 of the} vibration system having the movable plate from which is removed ,
The control means obtains a reduction amount ΔIs of the moment of inertia around the rotation center axis of the movable plate that is reduced by removing the part, and also reduces the reduction amount ΔIs, the resonance frequency f _1, and the resonance frequency. Based on f ₂ , an inertia moment I about the rotation center axis of the movable plate and a torsion spring constant K of the pair of connecting portions are obtained, and further, the reduction amount ΔIs, the inertia moment I, and the torsion are calculated. based on the spring constant K, determined the decrease ΔI of inertia required to match the resonant frequency f ₂ to the resonance frequency f ₀ of the vibration system of the object, on the basis of the obtained the decrease amount ΔI Finding a combination, operating the laser light irradiation means based on the obtained combination,
The laser light is irradiated on the plate surface of the movable plate by the laser beam irradiation means, and a part of the movable plate is removed to reduce the moment of inertia around the rotation center axis of the movable plate, and the vibration A resonance frequency adjusting device configured to adjust a resonance frequency of a system.   The said control means is comprised so that the site | part far from the rotation center axis | shaft of the said movable plate on the board surface of the said movable plate may be preferentially made into the irradiation position of the said laser beam. Resonance frequency adjustment device.   The control means is configured to preferentially set a position close to a line segment passing through the center of gravity of the movable plate and orthogonal to the rotation center axis as an irradiation position of the laser light. The resonance frequency adjusting apparatus as described.   The resonance frequency adjusting device according to any one of claims 1 to 3, wherein an upper limit value is set for each of the intensity and the irradiation time of the laser beam irradiated to the irradiation position of the laser beam. A light reflecting portion having light reflectivity is provided on one surface of the movable plate,
The said control part is comprised so that the irradiation position of the said laser beam may be determined in the surface on the opposite side to the surface in which the said light reflection part of the said movable plate is provided. The resonance frequency adjusting apparatus as described. A light reflecting portion having light reflectivity is provided on one surface of the movable plate,
5. The resonance frequency adjustment according to claim 1, wherein the control unit is configured to determine an irradiation site of the laser light on a surface of the movable plate on which the light reflecting unit is provided. apparatus. A resonance frequency of a vibration system having a movable plate and a pair of coupling portions connected to the movable plate and configured to rotate the movable plate while twisting and deforming the pair of coupling portions, A resonance frequency adjusting method for adjusting by irradiating a laser beam on a plate surface of a movable plate to remove a part of the movable plate,
A first step of measuring a resonance frequency f ₁ of the vibration system;
Based on the measurement result of the first step, a combination of an irradiation position where the laser beam is irradiated on the plate surface of the movable plate, an intensity of the laser beam irradiated to the irradiation position, and an irradiation time of the laser beam A second step for obtaining
And a third step of irradiating the laser beam on the plate surface of the movable plate based on the combination condition obtained in the second step,
In the second step, resonance of the vibration system having the movable plate partially removed by irradiating the laser beam with a predetermined intensity for a predetermined time at a predetermined position of the movable plate. Obtaining a frequency f ₂ and a reduction amount ΔIs of the moment of inertia around the rotation center axis of the movable plate that is reduced by removing the part;
Obtaining an inertia moment I about the rotation center axis of the movable plate and a torsion spring constant K of the pair of connecting portions based on the reduction amount ΔIs, the resonance frequency f ₁ and the resonance frequency f ₂ ; ,
The reduction .DELTA.Is, on the basis of the moment of inertia I and the torsional spring constant K, the resonance frequency f _2, the decrease ΔI of inertia required to match the resonance frequency f ₀ of the vibration system of the object The desired process;
And a step of obtaining the combination based on the obtained reduction amount ΔI .   The resonance frequency adjusting method according to claim 7, wherein in the second step, a portion of the movable plate on the surface of the movable plate that is distant from the rotation center axis of the movable plate is preferentially set as the irradiation position of the laser beam. .   9. The resonance frequency according to claim 8, wherein in the second step, a position close to a line segment passing through the center of gravity of the movable plate and orthogonal to the rotation center axis is preferentially set as the irradiation position of the laser beam. Adjustment method.   The resonance frequency adjusting method according to any one of claims 7 to 9, wherein an upper limit value is set for each of the intensity and the irradiation time of the laser beam irradiated to the irradiation position of the laser beam.

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