JP6424479B2 - Actuator and control method of actuator - Google Patents

Description

The present invention relates to a control method for actuators及beauty actuators.

  In recent years, with the development of MEMS (Micro Electro Mechanical Systems) technology, development of various MEMS devices is promoted. One such MEMS device is a rotary actuator that scans light (see, for example, Patent Document 1). The rotary actuator has a movable electrode which is a mirror, and a fixed electrode. The tilt angle of the movable electrode is controlled by a drive signal applied to the fixed electrode.

  In order to scan light with high accuracy, it is necessary to control the tilt direction and angle of the movable electrode with high accuracy. The rotary actuator disclosed in Patent Document 1 has a detection electrode. Then, the angle of the movable electrode is detected from the change in capacitance generated between the movable electrode and the detection electrode.

JP, 2005-208251, A

  The capacitance generated between the movable electrode and the detection electrode is detected as the potential of the detection electrode. However, since the detection electrode is located near the fixed electrode, the drive signal applied to the fixed electrode is mixed in with the potential of the detection electrode. It is also conceivable to remove this interference using a circuit. However, in this case, even if the rotary actuator is miniaturized, the circuit attached to the rotary actuator is enlarged, and as a result, the miniaturization of the rotary actuator is meaningless.

The present invention has been made in view of the above circumstances, and an object of the present invention is that the drive signal applied to the fixed electrode becomes noise of the position detection of the movable electrode even without a large-scale circuit. to provide a control method for suppressing possible luer actuator及beauty actuators.

Engaging luer actuator to the present invention includes a movable electrode, the support, the fixing member, the first fixed electrode, the second fixed electrode, the first detection electrode, second detection electrode, and a driving unit. The fixed member attaches the movable electrode to the support and serves as a rotation axis of the movable electrode. The first fixed electrode faces the first side of the movable electrode. The second fixed electrode is opposed to a second side which is a side opposite to the first side of the movable electrode. The first detection electrode faces the first side of the movable electrode, and is insulated from the movable electrode and the first fixed electrode. The second detection electrode faces the second side of the movable electrode, and is insulated from the movable electrode and the second fixed electrode. The drive unit inputs the first signal to the first fixed electrode, and inputs a second signal whose phase is opposite to the first signal to the second fixed electrode.

The method of the engaging luer actuator this embodiment, the actuators described above, based on the fluctuation sum or average of the potential of the potential and the second detecting electrode of the first detection electrode, the position of the movable electrode It is something to detect.

  According to the present invention, even if there is no large-scale circuit, it is possible to suppress that the drive signal applied to the fixed electrode becomes noise of position detection of the movable electrode.

It is a figure showing composition of a rotary type actuator concerning a 1st embodiment. FIG. 6 is an equivalent circuit diagram of a rotary actuator. It is a figure for demonstrating the waveform of the voltage which the detection part of the rotary actuator which concerns on a comparative example detected. It is a figure which shows the waveform of the voltage which the detection part of the rotary actuator which concerns on a present Example detected. It is a circuit diagram which shows the structure of the drive part which the rotary actuator concerning 2nd Embodiment has. It is a figure showing composition of a rotary type actuator concerning a 3rd embodiment. It is a figure which shows the structure of the rotary actuator which concerns on 4th Embodiment.

  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 configuration of a rotary actuator 100 according to the first embodiment. The rotary actuator 100 includes a support 110, a movable electrode 120, a fixed member 130, a first fixed electrode 142, a second fixed electrode 144, a first detection electrode 152, a second detection electrode 154, and a drive unit 200. ing. The first fixed electrode 142 and the second fixed electrode 144 constitute the fixed electrode 140 of the rotary actuator 100, and the first detection electrode 152 and the second detection electrode 154 constitute the detection electrode 150 of the rotary actuator 100. It is configured.

  The fixed member 130 serves as a rotation axis of the movable electrode 120 by attaching the movable electrode 120 to the support 110. The first fixed electrode 142 is opposed to the first side of the movable electrode 120. The second fixed electrode 144 is opposed to the second side of the movable electrode 120. The second side is the side opposite to the first side of the movable electrode 120. The first detection electrode 152 is insulated from the movable electrode 120 and the first fixed electrode 142, and faces the first side of the movable electrode 120. The second detection electrode 154 is insulated from the movable electrode 120 and the second fixed electrode 144, and faces the second side of the movable electrode 120. Then, the drive unit 200 inputs the first signal to the first fixed electrode 142, and inputs to the second fixed electrode 144 a second signal whose phase is opposite to that of the first signal. The second signal is, for example, a signal obtained by inverting the phase of the first signal. In this case, the amplitude of the second signal is approximately equal to the amplitude of the first signal.

  According to this embodiment, the phase of the second signal input to the second fixed electrode 144 is the reverse of the phase input to the first fixed electrode 142. Therefore, when the position of the movable electrode 120 is detected based on the fluctuation of the sum (or the average) of the electric potential of the first detection electrode 152 and the electric potential of the second detection electrode 154, the first fixed electrode 142 and the second fixation are detected. It can be suppressed that the signal applied to the electrode 144 becomes a noise for detecting the position of the movable electrode 120. The details will be described below.

  In the example shown to this figure, the planar shape of the movable electrode 120 is a rectangle. The first fixed electrode 142 is disposed at the center of the first side of the movable electrode 120. The first detection electrodes 152 are disposed at both ends of the first side. In addition, the second fixed electrode 144 is disposed at the center of the side (second side) of the movable electrode 120 that faces the first side. Then, second detection electrodes 154 are disposed at both ends of the second side. The first fixed electrode 142 and the second fixed electrode 144 are arranged in line symmetry with each other with respect to a line extending the fixing member 130. Further, the first detection electrode 152 and the second detection electrode 154 are also arranged at positions that are line symmetrical with respect to a line extending the fixing member 130.

  Further, the first side and the second side of the movable electrode 120 are each in a comb-like shape. The side of the first fixed electrode 142 and the first detection electrode 152 facing the movable electrode 120 is also in a comb shape, and is engaged with the first side of the movable electrode 120. Further, of the second fixed electrode 144 and the first detection electrode 152, the side facing the movable electrode 120 is also in a comb shape, and is engaged with the second side of the movable electrode 120. For this reason, the area of the part which mutually opposes the 1st fixed electrode 142, the 2nd fixed electrode 144, and the movable electrode 120 becomes large, As a result, the driving force of the movable electrode 120 becomes large. In addition, the area of the portion where the first detection electrode 152 and the second detection electrode 154 and the movable electrode 120 face each other becomes large, and as a result, the detection value by the first detection electrode 152 and the second detection electrode 154 Will grow.

  The support 110 faces each of two sides other than the first side and the second side among the four sides of the movable electrode 120. The fixed member 130 is provided for each of two sides of the movable electrode 120 facing the support 110. Specifically, the fixed member 130 is connected to the center of the side of the movable electrode 120 facing the support 110. The line connecting the two fixed members 130 is the rotation axis of the movable electrode 120. In the present embodiment, the support 110, the movable electrode 120, and the fixed member 130 are integrally formed.

  For example, the upper surface of the movable electrode 120 of the rotary actuator 100 is a mirror surface. The mirror surface is formed, for example, by forming a metal film (for example, an Al film) on the upper surface of the movable electrode 120. Then, by changing the angle of the movable electrode 120, the reflection angle of the light incident on the movable electrode 120 is changed. The rotary actuator 100 is used, for example, for an optical scanner or a motion sensor.

  The drive unit 200 controls the movement of the movable electrode 120. Specifically, when rotating the movable electrode 120, the drive unit 200 applies a first signal, which is an alternating voltage, between the movable electrode 120 and the first fixed electrode 142, and the movable electrode 120 and the second fixed electrode 142. A second signal, which is an alternating voltage, is applied between the fixed electrodes 144. The second signal is, for example, a signal obtained by inverting the first signal. However, the amplitude of the first signal and the amplitude of the second signal may be different. A direct current voltage determined in advance by the direct current voltage source 400 is applied to the movable electrode 120. The magnitude of the DC voltage is greater than either twice the amplitude of the first signal and twice the amplitude of the second signal.

  The rotary actuator 100 further includes a detection unit 300. The detection unit 300 determines the position of the movable electrode 120 based on the variation of the sum or average of the potential of the first detection electrode 152 and the potential of the second detection electrode 154. The detection result of the detection unit 300 is output to the drive unit 200. The driver 200 uses the output from the detector 300 to generate the first signal and the second signal.

  FIG. 2 is an equivalent circuit diagram of the rotary actuator 100. As shown in FIG. In the drawing, a combination of the first detection electrode 152 and the second detection electrode 154 is described as a detection electrode 150.

  The detection unit 300 is formed by connecting an amplifier, a resistor, and a capacitive element in parallel. The detection electrode 150 is connected to the input terminal of the detection unit 300. The detection electrode 150 and the movable electrode 120 constitute a variable capacitance element. The variable capacitance element is connected to a direct current voltage source 400.

  In addition, this variable capacitance element is connected to the second signal generation unit 220 through a capacitance element formed of the movable electrode 120 and the first fixed electrode 142, and a capacitance formed of the movable electrode 120 and the second fixed electrode 144. It is connected to the first signal generator 210 via an element. Due to this connection, noise caused by the first signal and noise caused by the second signal enter the input terminal of the detection unit 300.

  However, in the present embodiment, the second signal input to the second fixed electrode 144 is opposite in phase to the first signal input to the first fixed electrode 142. For this reason, in the variable capacitance element, the noise caused by the first signal and the noise caused by the second signal mutually cancel each other, and as a result, the noise entering the input terminal of the detection unit 300 becomes very small.

  Further, the first detection electrode 152 is opposed to the first fixed electrode 142, and the second fixed electrode 144 is opposed to the second detection electrode 154. Therefore, the detection unit 300 is also connected to a capacitive element formed of the second detection electrode 154 and the second fixed electrode 144, and a capacitive element formed of the first detection electrode 152 and the first fixed electrode 142. Also by this connection, the noise caused by the first signal and the noise caused by the second signal enter the input terminal of the detection unit 300. However, this noise is also very small for the reasons described above.

  FIG. 3 is a diagram for explaining the waveform of the voltage detected by the detection unit 300 of the rotary actuator 100 according to the comparative example. Specifically, FIG. 3A is a chart showing the position (displacement angle) of the movable electrode 120, and FIG. 3B is a chart showing a signal input to the fixed electrode 140. As shown in FIG. And FIG.3 (c) is a chart which shows the waveform of a voltage in the electrode 150 for detection. In this comparative example, as shown in FIG. 3B, the same signals are input to the first fixed electrode 142 and the second fixed electrode 144 that constitute the fixed electrode 140. And as shown to Fig.3 (a), the displacement angle of the movable electrode 120 is changing along the sine wave. However, as shown in FIG. 3C, the waveform of the voltage of the detection unit 300 is in the form of a broken sine wave. Specifically, this form is a form in which the sine wave is broken at the timing when the voltage of the signal input to the fixed electrode 140 changes. From this, it can be understood that the signal input to the fixed electrode 140 appears as noise in the detection voltage of the detection unit 300.

  FIG. 4 is a diagram showing a waveform of a voltage detected by the detection unit 300 of the rotary actuator 100 according to the present embodiment. FIG. 4A is a chart showing the position (displacement angle) of the movable electrode 120, and FIG. 4B is a chart showing a signal inputted to the fixed electrode 140. As shown in FIG. And FIG.4 (c) is a chart which shows the waveform of a voltage in the electrode 150 for detection. As shown in FIG. 4B, in the present embodiment, the phases of the first signal input to the first fixed electrode 142 and the second signal input to the second fixed electrode 144 are reversed. For this reason, as shown in FIG. 4C, the waveform of the voltage detected by the detection unit 300 has a shape close to a sine wave.

  As described above, according to the present embodiment, the second signal input to the second fixed electrode 144 has the phase opposite to that of the first order signal input to the first fixed electrode 142. The noise that enters the input terminal is very small. Therefore, the position of the movable electrode 120 can be detected with high accuracy. In addition, since the phase of the second signal may be reversed from that of the first signal, a large circuit may not be required.

Second Embodiment
FIG. 5 is a circuit diagram showing the configuration of the drive unit 200 of the rotary actuator 100 according to the second embodiment. The rotary actuator 100 according to this embodiment has the same configuration as the rotary actuator 100 according to the first embodiment except for the configuration of the drive unit 200.

  In the present embodiment, the second signal is obtained by inverting the phase of the first signal and further adjusting the amplitude. The details will be described below.

  The drive unit 200 includes a reference pulse generation unit 202. The reference pulse generated by the reference pulse generation unit 202 is input to the first signal generation unit 210 and the second signal generation unit 220.

  The first signal generation unit 210 has an amplification unit 215. The amplification unit 215 outputs a first signal. A capacitive element 211 and a first resistor 212 are connected in series in this order between the input terminal of the amplification unit 215 and the reference pulse generation unit 202. The input terminal of the amplification unit 215 is grounded via the second resistor 213 and the third resistor 214. The resistance value of the third resistor 214 is larger than the resistance value of the first resistor 212 and the resistance value of the second resistor 213 (for example, 10 times or more and 100 times or less). The resistance value of the second resistor 213 and the resistance value of the third resistor 214 are, for example, equal to each other.

  Similarly, the second signal generation unit 220 includes an amplification unit 225. The amplification unit 225 outputs a second signal. An inverter 226, a capacitive element 221, and a fourth resistor 222 are connected in series in this order between the input terminal of the amplifier 225 and the reference pulse generator 202. The input terminal of the amplifier 225 is grounded via the fifth resistor 223 and the sixth resistor 224. The resistance value of the sixth resistor 224 is larger (for example, 10 times or more and 100 times or less) than the resistance value of the fourth resistor 222 and the resistance value of the fifth resistor 223, and is the same as the resistance value of the third resistor 214 .

  In the circuit described above, the impedance of the signal path from the reference pulse generation unit 202 to the first fixed electrode 142 is somewhat different from the impedance of the signal path from the reference pulse generation unit 202 to the second fixed electrode 144 ing. Also, the impedance of the signal path from the first detection electrode 152 to the detection unit 300 is somewhat different from the impedance of the signal path from the second detection electrode 154 to the detection unit 300. For this reason, noise may remain in the detection value of the detection unit 300 even if the first signal is simply transferred and inverted as the second signal.

  Therefore, in the present embodiment, by adjusting at least one set of the resistance value of the fourth resistor 222 and the resistance value of the fifth resistor 223, and the resistance values of the first resistor 212 and the fourth resistor 222, The difference is reduced. In other words, the impedance calculated from the capacitive element 211, the first resistor 212, the second resistor 213, and the third resistor 214 is calculated from the capacitive element 221, the fourth resistor 222, the fifth resistor 223, and the sixth resistor 224. Impedance is different. For example, the resistance of the fourth resistor 222 is within a range where the sum of the resistance of the fourth resistor 222 and the resistance of the fifth resistor 223 is equal to the sum of the resistance of the first resistor 212 and the resistance of the second resistor 213. The value and the resistance value of the fifth resistor 223 are adjusted. As a result, the possibility of noise remaining in the detection value of the detection unit 300 can be reduced. Therefore, the position of the movable electrode 120 can be detected with higher accuracy.

Third Embodiment
FIG. 6 is a view showing the configuration of a rotary actuator 100 according to the third embodiment. The rotary actuator 100 according to the present embodiment is the same as the rotary actuator 100 according to the first embodiment or the rotary actuator 100 according to the second embodiment except for the following points.

  In the present embodiment, the first detection electrode 152 is disposed at the center of the first side of the movable electrode 120. The first fixed electrodes 142 are disposed at both ends of the first side. In addition, a second detection electrode 154 is disposed at the center of the second side of the movable electrode 120. The second fixed electrodes 144 are disposed at both ends of the second side.

  Also according to the present embodiment, the same effect as that of the first embodiment or the second embodiment can be obtained.

Fourth Embodiment
FIG. 7 is a view showing the configuration of a rotary actuator 100 according to the fourth embodiment. The rotary actuator 100 according to this embodiment is the same as the rotary actuator 100 according to the first embodiment except that each of the first fixed electrode 142 and the second fixed electrode 144 is divided into a plurality. It is similar to the rotary actuator 100 according to the embodiment of the present invention.

  Also according to the present embodiment, the same effect as that of the first embodiment or the second embodiment can be obtained.

  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. For example, the arrangement of the fixed electrode 140 and the detection electrode 150 is not limited to the above-described embodiment.

100 rotary actuator 110 support 120 movable electrode 130 fixed member 140 fixed electrode 142 first fixed electrode 144 second fixed electrode 150 detection electrode 152 first detection electrode 154 second detection electrode 200 drive unit 202 reference pulse generation unit 210 1st signal generation part 211 capacitive element 212 1st resistance 213 2nd resistance 214 3rd resistance 215 amplification part 220 2nd signal generation part 221 capacitive element 222 4th resistance 223 5th resistance 224 6th resistance 225 amplification part 226 inverter 300 detector 400 DC voltage source

Claims (4)

A movable electrode,
A support,
A fixed member attached to the support, the movable electrode being a rotation axis of the movable electrode;
A first fixed electrode facing the first side of the movable electrode;
A second fixed electrode facing a second side which is a side opposite to the first side among the movable electrodes;
A first detection electrode facing the first side of the movable electrode and insulated from the movable electrode and the first fixed electrode;
A second detection electrode facing the second side of the movable electrode and insulated from the movable electrode and the second fixed electrode;
A driving unit which inputs a first signal to the first fixed electrode and inputs a second signal whose phase is opposite to the first signal to the second fixed electrode;
A detection unit that detects the position of the movable electrode based on the sum or the average of the electric potential of the first detection electrode and the electric potential of the second detection electrode;
The equipped Rua actuator. In actuators of claim 1,
The second signal is the signal der luer actuator in which the first signal in opposite phase. In actuators of claim 2,
The drive unit is
A first signal generation unit that generates the first signal by amplifying a reference pulse, and further includes a resistance element and a capacitance element;
A second signal generation unit that generates the second signal by inverting the phase of the reference pulse, and includes a resistance element and a capacitance element;
Equipped with
The impedance is calculated from the resistance and the capacitor of the first signal generator, different from the impedance calculated from the resistance and the capacitor of the second signal generating unit luer actuator. A movable electrode,
A support,
A fixed member attached to the support, the movable electrode being a rotation axis of the movable electrode;
A first fixed electrode facing the first side of the movable electrode in plan view;
A second fixed electrode facing a second side which is a side opposite to the first side among the movable electrodes;
A first detection electrode facing the first side of the movable electrode and insulated from the movable electrode and the first fixed electrode;
A second detection electrode facing the second side of the movable electrode and insulated from the movable electrode and the second fixed electrode;
Prepare the Rua actuator to have a,
The movable electrode is driven by inputting a first signal to the first fixed electrode and inputting a second signal whose phase is opposite to that of the first signal to the second fixed electrode, and the potential of the first detection electrode and on the basis of the variation sum or average of the potential of the second detection electrode, for detecting a position of the movable electrode, the control method of the actuators.

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