JP6528535B2 - Actuator and measuring device - Google Patents

Description

The present invention relates to an actuator and a measuring device.

  In recent years, rotary actuators have been developed. Patent Document 1 describes an example of a rotary actuator. The rotary actuator includes a movable electrode, a frame, a shaft member, and a fixed electrode. The shaft member has the movable electrode attached to the frame. The shaft member serves as the rotation axis of the movable electrode. The fixed electrode faces the movable electrode in plan view. Patent Document 1 describes that this rotary actuator is used for an optical scanner.

  Patent Document 2 also describes an example of a rotary actuator. In Patent Document 2, this rotary actuator is used for an optical scanner. And in patent document 2, the inductor is provided in the movable reflection part. A permanent magnet is provided in the vicinity of the inductor. As a result, when current flows through the inductor, Lorentz force is generated in the inductor by the magnetic field from the permanent magnet. In Patent Document 2, the movable reflector is driven by this Lorentz force.

JP, 2014-21189, A JP 2003-195205 A

  In recent years, a magnetic field may be measured using a measuring device. The inventors examined a novel structure of the measuring device for measuring the magnetic field.

  The present invention has been made in view of the above circumstances, and an object of the present invention is to measure a magnetic field with a measuring device having a novel structure.

  The measuring device according to the present invention comprises a movable electrode, a frame, a shaft member, a fixed electrode, an inductor, and a terminal. The shaft member has the movable electrode attached to the frame. The shaft member serves as the rotation axis of the movable electrode. The fixed electrode faces the movable electrode in plan view. The inductor is provided on the movable electrode. The terminal is electrically connected to the inductor.

  According to the present invention, the magnetic field can be measured with a measuring device having a novel structure.

It is a figure showing composition of a measuring device concerning a 1st embodiment. It is a figure which shows an example of the detailed structure of the actuator main body shown in FIG. It is a figure showing the detailed structure of the actuator main part used for the measuring device concerning a 2nd embodiment. It is an AA 'cross section figure of FIG. It is a figure which shows the modification of FIG. It is a figure for demonstrating the manufacturing method of the measuring apparatus which has a soft-magnetic material layer shown in FIG. It is a figure for demonstrating the manufacturing method of the measuring apparatus which has a soft-magnetic material layer shown in FIG.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In all the drawings, the same components are denoted by the same reference numerals, and the description thereof will be appropriately omitted.

First Embodiment
FIG. 1 is a view showing the arrangement of a measurement apparatus according to the first embodiment. The measuring apparatus includes a frame 110, a movable electrode 120, a shaft member 130, a fixed electrode 140, an inductor 160, and a measuring terminal 500. The shaft member 130 attaches the movable electrode 120 to the frame 110. The shaft member 130 serves as a rotation axis of the movable electrode 120. The fixed electrode 140 faces the movable electrode 120 in plan view. The inductor 160 is provided on the movable electrode 120. The measurement terminal 500 is electrically connected to the inductor 160. The details will be described below.

  The measuring device is formed using a rotary actuator. The measuring device has an actuator body 100. The actuator body 100 includes a frame 110, a movable electrode 120, a shaft member 130, a fixed electrode 140, and a detection electrode 150. The actuator body 100 is formed by selectively etching a conductive member, for example, a silicon substrate. In this case, the frame 110, the movable electrode 120, and the shaft member 130 are integrated.

  The planar shape of the movable electrode 120 is rectangular. And two fixed electrodes 140 are provided so as to sandwich the movable electrode 120 in a plan view. The side (the side extending in the X direction in FIG. 1) of the movable electrode 120 facing the fixed electrode 140 has a comb shape. The frame 110 is opposed to two of the four sides of the movable electrode 120 which are not opposed to the fixed electrode 140 (sides extending in the Y direction in FIG. 1). The shaft member 130 is provided for each of two sides of the movable electrode 120 facing the frame 110. In detail, the shaft member 130 is connected to the center of the side of the movable electrode 120 facing the frame 110. The line connecting the two shaft members 130 is the rotation axis of the movable electrode 120.

  The side of the fixed electrode 140 facing the movable electrode 120 has a comb-like shape, and is engaged with the comb-tooth portion of the movable electrode 120. For this reason, the area of the part which the fixed electrode 140 and the movable electrode 120 mutually oppose becomes large, As a result, the driving force of the movable electrode 120 becomes large.

  The driving power of the actuator body 100 is supplied by the first DC power supply 400 and the AC power supply 410.

  The first DC power supply 400 is connected to the frame 110. As described above, the frame 110, the movable electrode 120, and the shaft member 130 are integrated. Therefore, the first direct current power supply 400 can apply a voltage to the movable electrode 120 through the frame 110 and the shaft member 130. The output voltage of the first DC power supply 400 is variable, and is controlled by the control unit 300.

  AC power supply 410 is connected to fixed electrode 140. In the present embodiment, the output of the AC power supply 410 is constant.

  The actuator body 100 also has a detection electrode 150. The detection electrode 150 is aligned with the fixed electrode 140 and faces the side of the movable electrode 120 facing the fixed electrode 140. In the example shown in the figure, the fixed electrode 140 is opposed to the central portion of the side of the movable electrode 120. The detection electrode 150 is provided to sandwich the fixed electrode 140, and is opposed to both ends of the side of the movable electrode 120. The fixed electrode 140 is larger than the detection electrode 150. In the example shown in the figure, the detection electrodes 150 are provided on two opposing sides of the movable electrode 120. That is, the detection electrodes 150 are provided so as to be line symmetrical with respect to the shaft member 130. However, the detection electrode 150 may be provided only on one side of the movable electrode 120. Further, the positions of the detection electrode 150 and the fixed electrode 140 may be reversed.

  In the example shown in the figure, the movable electrode 120 is provided with an inductor 160. The inductor 160 is spirally provided along the edge of the movable electrode 120. The inductor 160 is formed using metal (for example, Al). When the angle of the movable electrode 120 is changed while the magnetic field penetrates the region surrounded by the inductor 160, an induced electromotive force is generated at both ends of the inductor 160. Both ends of the inductor 160 are electrically connected to a voltmeter 510 (voltage measurement unit) via a measurement terminal 500. Thereby, the above-mentioned magnetic field can be measured based on the voltage (induced electromotive force) measured by the voltmeter 510.

  In the example shown in the figure, the magnetic field described above can be measured with high accuracy. In detail, in the example shown in the drawing, it is not necessary to flow a current in the vicinity of the inductor 160 in order to rotate the movable electrode 120. Specifically, in the example shown in the figure, the movable electrode 120 is driven by the voltage (voltage of the first DC power supply 400) applied to the movable electrode 120 and the voltage (voltage of the AC power supply 410) applied to the fixed electrode 140. Is rotating. In this case, it is not necessary to flow a current in the vicinity of the inductor 160. If such a current flows, such a current generates a new magnetic field. And such a magnetic field can be noise for the measuring device. In the example shown in the figure, it is not necessary to flow a current that can generate such noise. Therefore, the magnetic field penetrating the region surrounded by the inductor 160 can be measured with high accuracy.

  In the example shown in the figure, when the movable electrode 120 is rotated, the movable electrode 120 has a constant frequency (for example, 1 kHz) between a certain angle (for example, + 10 °) and another constant angle (for example, -10 °). Vibrate with). In this case, when the magnetic field described above is a static magnetic field, the induced electromotive force generated at both ends of the inductor 160 oscillates between a constant positive voltage and a constant negative voltage. However, the method of rotating the movable electrode 120 is not limited to this example.

  In the example shown in the figure, the measurement terminal 500 is disposed outside the actuator body 100. However, the measurement terminal 500 may be disposed on the actuator body 100 (for example, the frame 110).

  The amount of rotation of the movable electrode 120 is detected using the capacitance detection unit 200. Specifically, the capacitance between the movable electrode 120 and the detection electrode 150 changes with the amount of rotation of the movable electrode 120. The capacitance detection unit 200 detects the capacitance to detect the amount of rotation of the movable electrode 120.

  In the example shown in the figure, the capacitance detection unit 200 includes an operational amplifier 210, a capacitive element 220, a resistive element 230, and a second DC power supply 240.

  The capacitive element 220 and the resistive element 230 are in parallel with each other, and are connected to the inverting input terminal of the operational amplifier 210 and the output terminal of the operational amplifier 210. In other words, the inverting input terminal and the output terminal of the operational amplifier 210 are connected to each other through the capacitive element 220 and connected to each other through the resistive element 230. Thus, the op amp 210 is virtually grounded.

  The second DC power supply 240 is connected to the noninverting input terminal of the operational amplifier 210. The output voltage of the second DC power supply 240 is variable and controlled by the control unit 300.

  In such a configuration, when the amount of charge stored in the capacitive element 220 changes, the output of the operational amplifier 210 also changes. Here, when the capacitance between the movable electrode 120 and the detection electrode 150 changes and the amount of charge accumulated in the detection electrode 150 changes, the amount of charge accumulated in the capacitive element 220 also changes accordingly. On the other hand, even if the voltage of the movable electrode 120 changes, the amount of charge accumulated in the detection electrode 150 changes, so the amount of charge accumulated in the capacitive element 220 changes. Thus, in addition to the capacitance between the movable electrode 120 and the detection electrode 150, the factor that affects the output of the operational amplifier 210 is the voltage of the movable electrode 120.

  The control unit 300 receives the output of the operational amplifier 210, that is, the amount of rotation of the movable electrode 120. Then, the control unit 300 controls the output voltage of the first DC power supply 400 (that is, the voltage of the movable electrode 120) and the output voltage of the second DC power supply 240 based on the amount of rotation of the movable electrode 120. As described above, the operational amplifier 210 is virtually grounded. Therefore, the voltage at the inverting input terminal of the operational amplifier 210 is approximately equal to the voltage at the non-inverting input terminal of the operational amplifier 210. Thus, the control unit 300 can control the voltage of the detection electrode 150 by controlling the output voltage of the second DC power supply 240.

  Next, the operation of the control unit 300 will be described. First, the control unit 300 controls the output voltage of the first DC power supply 400 so that the amount of rotation of the movable electrode 120 becomes a desired value. Here, the controller 300 controls the output voltage of the second DC power supply 240. Specifically, the output voltage of the second DC power supply 240 is changed such that the difference between the output voltage of the first DC power supply 400 and the output voltage of the second DC power supply 240 falls within the reference range. As described above, since the operational amplifier 210 is virtually grounded, the output voltage of the second DC power supply 240 is the voltage of the detection electrode 150. Therefore, the voltage between the movable electrode 120 and the detection electrode 150 is within the reference range.

  Here, even if the output voltage of the first DC power supply 400 is a value that can obtain a desired amount of rotation because the temperature of the movable electrode 120 changes and the shape of the movable electrode 120 is distorted, The amount of rotation sometimes does not reach a desired value. In such a case, the control unit 300 performs feedback control of the output voltage of the first DC power supply 400 so that the rotation amount of the movable electrode 120 becomes a specified amount using the output from the capacitance detection unit 200. Specifically, when the amount of rotation (voltage) output from the capacitance detection unit 200 is not within the reference range, the control unit 300 changes the output voltage of the first DC power supply 400. Thereby, the amount of rotation of the movable electrode 120 changes. Also, along with this, the capacitance between the detection electrode 150 and the movable electrode 120 also changes, and as a result, the detection value (output voltage) of the capacitance detection unit 200 also changes.

  In a general method of using the operational amplifier 210, the non-inverting input terminal of the operational amplifier 210 is grounded. In this case, when the voltage of the movable electrode 120 is changed to control the amount of rotation of the movable electrode 120, the voltage between the detection electrode 150 and the movable electrode 120 also changes. In this case, the factor that causes the change in the detection value (output voltage) of the capacitance detection unit 200 is the two of the capacitance between the detection electrode 150 and the movable electrode 120 and the voltage of the detection electrode 150. Therefore, it is necessary to remove the amount of change caused by the change in voltage of the movable electrode 120 from the amount of change in the detection value (output voltage) of the capacitance detection unit 200.

  On the other hand, in the present embodiment, the control unit 300 also changes the output voltage of the second DC power supply 240 in accordance with the change of the output voltage of the first DC power supply 400. Specifically, the output voltage of the second DC power supply 240 is changed so that the difference between the output voltage of the first DC power supply 400 and the output voltage of the second DC power supply 240 does not go out of the reference range. Thereby, even if the control unit 300 changes the voltage of the movable electrode 120, the voltage between the detection electrode 150 and the movable electrode 120 does not change. Therefore, the factor that causes the change in the detection value (output voltage) of the capacitance detection unit 200 is only the capacitance between the detection electrode 150 and the movable electrode 120. Therefore, it is not necessary to correct the amount of change caused by the change in voltage of the movable electrode 120 from the amount of change in the detection value (output voltage) of the capacitance detection unit 200. In other words, since the voltage between the movable electrode 120 and the detection electrode 150 is constant, the factor affecting the amount of charge accumulated in the movable electrode 120 is the amount of rotation of the movable electrode 120. Therefore, according to the present embodiment, the amount of calculation in the control unit 300 can be reduced.

  FIG. 2 is a view showing an example of the detailed structure of the actuator main body 100 shown in FIG. In the example shown in the drawing, the wiring 162 is provided for each of the two shaft members 130. One end of the wiring 162 is connected to the inductor 160, and the other end reaches the frame 110. Further, the other end of the wiring 162 is electrically connected to the measurement terminal 500. Thus, the inductor 160 can be electrically connected to the measurement terminal 500 (in other words, the voltmeter 510) through the wiring 162.

  As described above, according to the present embodiment, the movable electrode 120 includes the inductor 160. Both ends of the inductor 160 are electrically connected to the voltmeter 510 via the measurement terminal 500. Thereby, the induced electromotive force generated at both ends of the inductor 160 can be measured by the voltmeter 510. Then, based on the voltage (induced electromotive force) measured by the voltmeter 510, the magnetic field penetrating the inductor 160 can be measured.

Second Embodiment
FIG. 3 is a view showing the detailed structure of the actuator main body 100 used in the measurement apparatus according to the second embodiment, and corresponds to FIG. 2 of the first embodiment. The measuring apparatus according to the present embodiment has the same configuration as the measuring apparatus according to the first embodiment except for the following points.

  In the example shown in the figure, the soft magnetic material layer 170 is provided on the movable electrode 120. The soft magnetic material layer 170 is located in the area surrounded by the inductor 160. The soft magnetic material layer 170 has high permeability. Thereby, even if the magnetic field penetrating the inductor 160 is small, the induced electromotive force generated at both ends of the inductor 160 can be made large. In other words, the resolution of the magnetic field that can be measured by the measuring device can be reduced.

The soft magnetic material layer 170 has a relative permeability of, for example, 5,000 or more and 100,000 or less. Specifically, the soft magnetic material layer 170 is formed using at least one of permalloy, tough palm, Mn—Zn ferrite, Co-based amorphous alloy, and nanocrystal alloy fine met. When the relative permeability of the soft magnetic material layer 170 is 10,000, the measuring device can measure the magnetic flux density in the range of approximately 10 ⁻⁵ T to ^{10 −10} T.

  FIG. 4 is a cross-sectional view taken along line AA 'of FIG. In the example shown in the drawing, the insulating layer 182 (for example, a silicon oxide film) is stacked on the movable electrode 120. The inductor 160 and the soft magnetic material layer 170 are located on the insulating layer 182. Furthermore, the inductor 160 and the soft magnetic material layer 170 are covered with an insulating layer 184 (for example, a silicon oxide film).

  The film thickness T of the insulating layer 182 is somewhat thick, for example, 0.2 μm or more and 0.5 μm or less. Thus, the inductor 160 and the soft magnetic material layer 170 can be positioned apart from the movable electrode 120 by a distance that is relatively large. Thereby, the eddy current that can be generated in the movable electrode 120 by the magnetic field generated by the inductor 160 can be reduced. Such eddy currents generate a new magnetic field. And such a magnetic field can be noise for the measuring device. In the example shown in the figure, the insulating layer 182 can position the inductor 160 and the soft magnetic material layer 170 away from the movable electrode 120 to some extent. Thereby, the above-mentioned eddy current can be made small.

  FIG. 5 is a view showing a modification of FIG. In the example shown in the figure, the inductor 160 is embedded in the soft magnetic material layer 170. Specifically, the soft magnetic material layer 170 includes a first soft magnetic material layer 172 and a second soft magnetic material layer 174. The first soft magnetic material layer 172 and the second soft magnetic material layer 174 may be soft magnetic material layers of the same type, or may be soft magnetic material layers of different types. The first soft magnetic material layer 172 is located on the movable electrode 120. The second soft magnetic material layer 174 is located on the first soft magnetic material layer 172. The inductor 160 is located on the first soft magnetic material layer 172 and covered by the second soft magnetic material layer 174. In this case, substantially all of the magnetic field generated from the inductor 160 propagates inside the soft magnetic material layer 170. In other words, the magnetic field from the inductor 160 can be suppressed from reaching the movable electrode 120.

  In the example shown in the figure, the inductor 160 is covered with the insulating layer 180 at its periphery. This can prevent the inductor 160 from being electrically connected to the soft magnetic material layer 170. In detail, the insulating layer 180 includes an insulating layer 182 and an insulating layer 184. Insulating layers 182 may be the same type of insulating layer (eg, silicon oxide film or silicon nitride film), or may be different types of insulating layers. The insulating layer 182 is located on the first soft magnetic material layer 172. The insulating layer 184 is located on the insulating layer 182. The inductor 160 is located on the insulating layer 182 and covered by the insulating layer 184.

  Each of FIGS. 6 and 7 is a view for explaining the method of manufacturing the measuring apparatus having the soft magnetic material layer 170 shown in FIG. 5, and corresponds to FIG. First, as shown in FIG. 6A, the first soft magnetic material layer 172 and the insulating layer 182 are stacked in this order on the movable electrode 120. The first soft magnetic material layer 172 is formed by using, for example, sputtering.

  Next, as shown in FIG. 6B, the inductor 160 is formed on the insulating layer 182. The inductor 160 is formed, for example, by forming a resist pattern on a metal film (for example, an Al film) and etching the metal film using the resist pattern as a mask.

  Next, as shown in FIG. 7A, the insulating layer 184 is formed on the insulating layer 182 and the inductor 160.

  Next, as shown in FIG. 7B, the insulating layer 182 and the insulating layer 184 are selectively removed. Thus, the insulating layer 182 and the insulating layer 184 remain in a region overlapping with the inductor 160 in plan view and the periphery thereof. Furthermore, the first soft magnetic material layer 172 is exposed in the region surrounded by the inductor 160 in plan view.

  Then, the second soft magnetic material layer 174 is formed on the first soft magnetic material layer 172 and the insulating layer 184. Thereby, the soft magnetic material layer 170 shown in FIG. 5 is formed.

  Also in this embodiment, the same effect as that of the first embodiment can be obtained. Furthermore, according to the present embodiment, by using the soft magnetic material layer 170, the induced electromotive force between both ends of the inductor 160 can be made large. This makes it possible to reduce the resolution of the magnetic field that can be measured by the measurement device.

  Although the embodiments of the present invention have been described above with reference to the drawings, these are merely examples of the present invention, and various configurations other than the above can also be adopted.

100 actuator main body 110 frame 120 movable electrode 130 shaft member 140 fixed electrode 150 detection electrode 160 inductor 162 wiring 170 soft magnetic material layer 172 first soft magnetic material layer 174 second soft magnetic material layer 180 insulating layer 182 insulating layer 184 insulating layer 184 insulating Layer 200 Capacitance detection unit 210 Op amp 220 Capacitive element 230 Resistance element 240 Second DC power supply 300 Control unit 400 First DC power supply 410 AC power supply 500 Measurement terminal 510 Voltmeter

Claims (7)

A movable electrode,
A frame having a portion aligned in one direction with the movable electrode in a plan view ;
A shaft member having the movable electrode attached to the part of the frame and having an axis extending in the one direction, the axis serving as a rotation axis of the movable electrode ;
A fixed electrode facing the movable electrode in plan view;
An inductor provided on the movable electrode;
Equipped with a,
The actuator, wherein the movable electrode is rotatable about the rotation axis by a voltage between the movable electrode and the fixed electrode . In the actuator according to claim 1,
Provided on the shaft member, the actuator comprising a wiring electrically connected to the inductor. The actuator according to claim 1 or 2
Wherein provided on the movable electrode, the actuator comprising at least a portion is located inside of the inductor when viewed soft magnetic material layer. In the actuator according to claim 3 ,
It comprises an insulating layer located on the movable electrode and having a thickness of 0.2 μm to 0.5 μm,
The inductor and the soft magnetic material layer, an actuator positioned on the insulating layer. In the actuator according to claim 3 ,
The actuator is embedded in the soft magnetic material layer. In the actuator according to claim 5 ,
The soft magnetic material layer is
A first soft magnetic material layer located on the movable electrode;
A second soft magnetic material layer located on the first soft magnetic material layer;
Have
It said inductor, said located first soft magnetic material layer, and an actuator which is covered with the second soft magnetic material layer.   The actuator according to any one of claims 1 to 6,
  A movable electrode drive unit for supplying the voltage for rotating the movable electrode of the actuator;
  A voltage measurement unit electrically connected to the inductor;
Measuring device comprising:

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