JP6199574B2 - Voltage sensor - Google Patents

Description

  The present invention relates to a voltage sensor.

  Conventionally, there are various methods for measuring voltage. For example, there are a method of dividing a voltage with a voltage dividing resistor and measuring the divided voltage with a voltmeter, and a method of taking out a current proportional to the voltage and measuring the voltage using a so-called Hall effect.

  There is also a voltage measurement method using the electric photoelectric effect. The current sensor in this measurement method includes, for example, a Pockels element, a quarter wavelength plate, a polarizer, an analyzer, and the like. In this voltage sensor, the optical signal output from the light source is polarized by the polarizer and enters the Pockels element, and is subjected to light modulation corresponding to the magnitude of the voltage in the Pockels element. The optical signal subjected to the optical modulation is transmitted to the analyzer through the quarter wavelength plate. The optical signal output from the analyzer is received and detected by a predetermined optical receiver, and the voltage applied to the Pockels element can be measured (see, for example, Patent Document 1).

Japanese Patent Laid-Open No. 3-146875

  However, the above three voltage sensors have the following problems. First, in a voltage sensor that measures a divided voltage, a voltage cannot be measured accurately unless a high-precision resistor is used. In particular, since the resistance value of the resistance varies depending on the temperature, there is a problem in measuring the voltage with high accuracy. In addition, there is a possibility that a high voltage to be measured is applied to a low voltage on the measurement side at the time of a resistance failure, so that an insulating means or the like must be separately provided in order to ensure safety, and the number of parts increases.

  In addition, a voltage sensor that measures voltage using the Hall effect requires a magnetic core for collecting magnetism, resulting in an increase in the number of components and an increase in size. In particular, in this type of sensor, a negative feedback type may be used to achieve output linearity, but current consumption is required to cancel the generated magnetic field, resulting in an increase in power consumption.

  Furthermore, the above two methods are disadvantageous for constant voltage monitoring of a battery or the like because it is necessary to take out a current from a measurement target during measurement.

  Furthermore, the voltage sensor described in Patent Document 1 requires components such as a Pockels element, a quarter-wave plate, a polarizer, and an analyzer, which increases the number of components and requires alignment of the optical axis. As a result, the assembly becomes complicated.

  The present invention has been made to solve such a conventional problem. The object of the present invention is to improve the accuracy of voltage measurement and reduce power consumption without taking out a current from a measurement target. An object of the present invention is to provide a voltage sensor capable of suppressing an increase in the number of parts and an increase in the number of parts, and also suppressing the complexity of assembly.

The voltage sensor of the present invention includes a vibrator supported by a mechanical suspension, a drive electrode for vibrating the vibrator, and a fixed electrode arranged to face each other through a gap in the vibrator. The measurement target is applied to the fixed electrode by applying a voltage to be measured to the vibrator, and an electrostatic attraction is applied to the vibrator, and the resonance frequency of the vibrator is changed by the action of the electrostatic attraction. The fixed electrode is provided on an insulating layer on a substrate such as silicon, and the vibrator is formed on the substrate and is different from the fixed electrode and the driving electrode. is connected to the other end of the suspension at one end to the electrode is connected, by floating structure in the air is fixed on the substrate, the driving electrode, on the substrate so as to face with said vibrator Is location, characterized in that it is arranged parallel to the substrate together with the fixed electrode and the vibrator.

  According to the voltage sensor of the present invention, the electrostatic attraction force is applied to the vibrator by applying the voltage to be measured to the fixed electrode disposed opposite to the vibrator supported by the mechanical suspension via the gap. The voltage to be measured is calculated by changing the resonance frequency of the vibrator. Here, when a voltage to be measured is applied to the fixed electrode, the electrostatic attraction caused by this voltage substantially changes the spring constant of the suspension, and the resonance frequency of the vibrator changes. Since this change has a certain correlation with the magnitude of the voltage to be measured, the value of the voltage to be measured can be measured from the changed resonance frequency. As described above, in the present invention, it is not necessary to use a high-precision resistor, the accuracy of voltage measurement can be improved, and an insulating means or the like is not necessary, and an increase in the number of parts can be suppressed. Further, since the measurement is performed by using the electrostatic attractive force that generates the voltage to be measured, the voltage can be measured with almost no current flowing from the measurement target. In addition, it is not necessary to use a magnetic collecting core or the like, optical components can be suppressed, an increase in power consumption and an increase in the number of components can be suppressed, and complicated assembly can also be suppressed.

  The voltage sensor described above preferably includes a mechanical stopper or an insulator so that the vibrator and the fixed electrode to which the voltage to be measured is applied are not short-circuited.

  According to this voltage sensor, since the mechanical stopper or the insulator is provided so that the vibrator and the fixed electrode are not short-circuited, a short-circuit between the vibrator and the fixed electrode is prevented, and safety can be improved.

  In any of the voltage sensors described above, the relationship between the vibrator and the fixed electrode to which the voltage to be measured is applied is preferably a parallel plate electrode.

  According to this voltage sensor, since the relationship between the vibrator and the fixed electrode is a parallel plate electrode, the gap dependency of the force acting between the electrodes is high. In addition, the slope of the electrostatic attraction with respect to the gap change becomes an equivalent spring constant for the electrostatic attraction. By applying the voltage to be measured, the total equivalent spring constant including the suspension changes, and the resonance frequency changes. The frequency is an amount that can be measured accurately, which can improve the measurement resolution. .

  Moreover, in the voltage sensor described in any one of the above, it is preferable to use electrostatic attraction to excite the vibrator.

  According to this voltage sensor, electrostatic attraction is used to excite the vibrator. Since the resonance frequency can be measured even with a small vibration amplitude, a low voltage at which the electronic circuit operates can be used. Therefore, it is suitable for digitizing a voltage sensor.

  In the voltage sensor described above, the electrode for exciting the vibrator is preferably a comb electrode.

  According to this voltage sensor, since the electrode for exciting the vibrator is a comb-teeth electrode, even if the vibrator is moved by electrostatic attraction, if the comb-teeth electrode is used, the dependency of the gap is small and an AC voltage is applied. The influence on the resonance frequency due to can be reduced.

  In the voltage sensor described above, an amplitude detection unit that is electrically connected to the vibrator and detects the amplitude of the vibrator, and a voltage to be measured applied to the fixed electrode are applied to the amplitude detection unit. It is preferable to provide an insulating means for preventing the above.

  According to this voltage sensor, since the insulating means for preventing the voltage to be measured from being applied to the amplitude detecting means is provided, the amplitude detecting means is electrically insulated from the DC component of the high voltage system to be measured. Thus, safety can be further improved.

Further, in the voltage sensor described above, the vibrator, a first electrode connected to the AC generating circuit to apply an AC voltage to the vibrator is electrically connected to said transducer A portion, a second electrode portion electrically connected to the fixed electrode , and an insulating means for insulating the first electrode portion and the second electrode portion , the insulating means It is preferable to prevent the voltage to be measured applied to the fixed electrode from being applied to the AC generation circuit .

  According to this voltage sensor, since the insulation means for preventing the voltage to be measured from being applied to the AC generation circuit is provided, the AC generation circuit is electrically insulated from the DC component of the high voltage system to be measured. Thus, safety can be further improved.

  According to the present invention, it is possible to improve the accuracy of voltage measurement, suppress an increase in power consumption and an increase in the number of components without taking out a current from a measurement target, and suppress an increase in assembly complexity. A voltage sensor can be provided.

It is a basic lineblock diagram showing the principle of the voltage sensor concerning the embodiment of the present invention. It is a perspective view which shows the voltage sensor which concerns on this embodiment. It is an enlarged view of the A section shown in FIG. FIG. 3 is an enlarged top view of the voltage sensor shown in FIG. 2. It is a figure which shows the resonant frequency before a change, and the resonant frequency after a change. It is a graph which shows an example of the correlation with the voltage used as a measuring object, and the resonance frequency. It is a graph which shows an example of the correlation with the voltage used as a measuring object, and the resonant frequency, Comprising: The measured value is shown. It is a perspective view which shows the detail of a comb-tooth electrode, Comprising: The analysis model is shown. It is an enlarged view which shows the contact part of the stopper shown in FIG. 2, and its periphery, (a) shows the case where the voltage used as a measuring object is 0V, (b) shows the case where the voltage used as a measuring object is 100V (C) shows the case where the voltage to be measured is 147V, and (d) shows the case where the voltage to be measured is 150V. It is a graph which shows the correlation with the voltage used as a measuring object, and the gap of a vibrator and a fixed electrode. It is sectional drawing which shows the 1st modification of the voltage sensor which concerns on this embodiment. It is sectional drawing which shows the 2nd modification of the voltage sensor which concerns on this embodiment. It is sectional drawing which shows the 3rd modification of the voltage sensor which concerns on this embodiment. It is sectional drawing which shows the 4th modification of the voltage sensor which concerns on this embodiment. It is sectional drawing which shows the 5th modification of the voltage sensor which concerns on this embodiment.

  DESCRIPTION OF EXEMPLARY EMBODIMENTS Hereinafter, preferred embodiments of the invention will be described with reference to the drawings. FIG. 1 is a basic configuration diagram showing the principle of a voltage sensor according to an embodiment of the present invention. As shown in FIG. 1, the voltage sensor 1 according to the present embodiment includes a mechanical suspension 10, a vibrator 20, a fixed electrode 30, and a calculation unit 40.

  The suspension 10 supports the vibrator 20. Let the spring constant of the suspension 10 be k. The vibrator 20 is a flat plate electrode supported by the suspension 10, and can be vibrated by the elastic force of the suspension 10. The mass of the vibrator 20 is m.

  The fixed electrode 30 is a flat plate electrode disposed so as to face the gap in the vibrator 20, and has a parallel plate electrode relationship with the vibrator 20. Note that S is an area where the vibrator 20 and the fixed electrode 30 face each other. Also, let g be the initial gap between the two.

なる関係式（１）に基づく共振周波数ｆ_ｒで振動することとなる。 When an AC voltage is applied to the vibrator 20 in such a voltage sensor 1, the vibrator 20 vibrates in the direction in which the distance from the fixed electrode 30 increases or decreases (the left-right direction in the figure) due to the elastic force of the suspension 10. At this time, the vibrator 20

Made based on equation (1) it becomes to vibrate at the resonance frequency f _r.

なお、式（２）においてε_０はギャップｇ間の誘電率であり、Ｖは測定対象となる電圧である。 Furthermore, it is assumed that a voltage to be measured is applied to the fixed electrode 30. At this time, an electrostatic attractive force is applied from the fixed electrode 30 to the vibrator 20 and is displaced by a distance x. Electrostatic attraction can be represented as an equivalent spring constant k _e shown in equation (2).

In Equation (2), ε ₀ is a dielectric constant between the gaps g, and V is a voltage to be measured.

As a result, the vibrator 20 vibrates at the resonance frequency f _r ′ shown in Expression (3).

Here, the equivalent spring constant k _e of the formula (2), since the changes in accordance with the magnitude of the voltage V applied to the fixed electrode 30, voltage for formula (3) to indicate the resonant frequency f _{r 'V} It reflects the size of.

Therefore, the calculation unit 40 can calculate the voltage to be measured from the resonance frequency f _r ′ of the vibrator 20.

  FIG. 2 is a perspective view showing the voltage sensor 1 according to the present embodiment. As shown in FIG. 2, the voltage sensor 1 is a micro voltage sensor created using a MEMS (Micro Electro Mechanical Systems) processing technique.

  As shown in FIG. 2, in the voltage sensor 1, the vibrator 20 has an elongated shape that reduces the mass in order to increase the resonance frequency. In addition, the suspension 10 is provided at each of both ends of the elongated vibrator 20 and is configured to support the vibrator 20 from both ends. Furthermore, each suspension 10 has a shape that is folded in a U-shape.

  In addition to the configuration shown in FIG. 1, the voltage sensor 1 includes a driving electrode 50 and first and second electrodes 61 and 62 connected to ends of the suspensions 10 opposite to the connection side of the vibrator 20. And a stopper 70.

  The driving electrode 50 excites and vibrates the vibrator 20 by applying an alternating voltage. FIG. 3 is an enlarged view of a portion A shown in FIG. As shown in FIG. 3, the driving electrode 50 includes a comb electrode 51 extending in the direction of the vibrator 20. Similarly, the vibrator 20 shown in FIG. 2 includes a comb electrode 21 extending in the direction of the driving electrode 50. The comb electrodes 21 and 51 are arranged so as to mesh with each other without contact.

  Such a voltage sensor 1 can be produced, for example, by processing an SOI wafer. Specifically, patterning is performed using a single mask, and etching is performed using Deep-RIE. In order to release the vibrator 20 which is a movable part, sacrificial layer etching is performed using vapor phase HF.

  As described above, the vibrator 20 has a structure that floats in the air while being supported by the suspension 10 for vibration. In the actual product (device layer x: 1125 μm, y: 1585 μm, z: 25 μm), the vibrator 20 sinks up to 66 nm with respect to the other electrodes 30 and 50, but the sacrificial layer is 2 μm, so the sinking amount Is as small as 1/30 of the sacrificial layer and does not contact the handle layer. In addition, the comb-tooth electrode 51 and the fixed electrode 30 may appear to be floating in the air due to the illustrated relationship, but this is because the sacrificial layer etching has partially progressed and is actually fixed to the handle layer. ing.

  FIG. 4 is an enlarged top view of the voltage sensor 2 shown in FIG. As shown in FIGS. 2 and 4, four stoppers 70 are arranged on the fixed electrode 30 side with respect to the vibrator 20 (only two are shown in FIG. 4). This stopper 70 has a structure that is not electrically connected anywhere. Such a stopper 70 includes a main body portion 71, a spring portion 72, and a contact portion 73.

  The main body 71 has a substantially square shape when viewed from above, and an elongated spring portion 72 is formed from one apex of the square. The tip of the spring portion 72 protrudes slightly toward the vibrator 20 side than the fixed electrode 30. Further, the spring portion 72 extends from the apex portion toward the vibrator 20 side, is folded back at 90 degrees, extends along a square side, and is folded back again toward the vibrator 20 side by 90 degrees. That is, the spring portion 72 has a shape that is bent at 90 degrees twice in the middle, and has a configuration having an elastic force by turning back at 90 degrees. Due to the presence of such a stopper 70, even if the vibrator 20 is excessively pulled toward the fixed electrode 30 by electrostatic attraction, the vibrator 20 comes into contact with the contact portion 73, and the vibrator 20 and the fixed electrode are contacted. A short circuit with 30 will be prevented. Even when the vibrator 20 comes into contact with the stopper 70, the elastic force of the spring portion 72 has a function of relaxing the force at the time of contact, so that the contact portion 73 is prevented from being bent or bent.

Next, the operation of the voltage sensor 1 according to this embodiment will be described. First, in the voltage sensor 1 of the present embodiment, the driving electrode 50 generates an alternating voltage. Thereby, the electrostatic attraction is generated by the voltage of the driving electrodes 50, the vibrator 20 because the voltage is AC becomes possible to vibrate having a predetermined resonant frequency f _r.

At this time, it is assumed that the voltage V to be measured is applied to the fixed electrode 30. As a result, the electrostatic attractive force shown in Expression (2) is generated, and the vibrator 20 vibrates with the resonance frequency f _r ′ as shown in Expression (3).

Figure 5 is a diagram showing a resonance frequency f _{r 'after} the resonance frequency f _r and the change before the change. As shown in FIG. 5, when the voltage V to be measured is applied, the resonance frequency varies decreases from f _r to f _{r '.}

The computing unit 40 computes the magnitude of the voltage V to be measured from the resonance frequency f _r ′. Note that the computing unit 40 needs to measure the amount of displacement of the vibrator 20 in order to measure the resonance frequency f _r ′. At this time, the voltage sensor 1 irradiates the vibrator 20 with laser light, and obtains the displacement amount of the vibrator 20 from the fluctuation width of the reflected light. Further, the voltage sensor 1 may measure the displacement amount of the vibrator 20 from the change in capacitance due to the change in the electrode gap g. In addition, when calculating | requiring a displacement amount from an electrostatic capacitance, you may utilize the fixed electrode 30 as it is, and may install the parallel plate electrode for measuring a displacement amount separately.

  FIG. 6 is a graph showing an example of the correlation between the voltage V to be measured and the resonance frequency. When each resonance frequency is measured with the voltage to be measured as 0V, 50V, 100V, 120V, 145V, and 147V, as shown in FIG. It became. Thus, it became clear that the resonance frequency changes with the voltage V to be measured. The resonance frequency was the frequency at which the displacement amount (vibration amplitude) of the vibrator 20 was less than 3 μm.

  FIG. 7 is a graph showing an example of the correlation between the voltage V to be measured and the resonance frequency, and shows measured values. In FIG. 7, the actual measurement values are the same as those described with reference to FIG.

The computing unit 40 described above stores correlation data as shown in FIG. Therefore, when the resonance frequency f _r ′ is measured, the voltage V to be measured is calculated based on the correlation data as shown in FIG. The correlation data to be stored is preferably an actual measurement value.

  As described above, in this embodiment, it is not necessary to use a high-precision resistor as in the prior art, it is possible to improve the accuracy of voltage measurement, and there is no need for an insulating means, and an increase in the number of parts can be suppressed. . Further, since the measurement is performed by using the electrostatic attractive force that generates the voltage to be measured, the voltage can be measured with almost no current flowing from the measurement target. In addition, it is not necessary to use a magnetic collecting core or the like, optical components can be suppressed, an increase in power consumption and an increase in the number of components can be suppressed, and complicated assembly can also be suppressed.

が単位ユニットあたりの静電容量である。櫛歯対の数をＮとすると、全体の発生力は以下のように表せる。

In the present embodiment, the vibrator 20 is excited and oscillated by the comb-tooth electrodes 21 and 51. Therefore, there are the following advantages. FIG. 8 is a perspective view showing details of the comb electrodes 21 and 51, and shows an analysis model. In FIG. 8, the comb tooth length is l, the width is w, and the distance between the tip of the comb tooth and the counter electrode is s. The initial comb tooth overlap is l · s. The distance between the side walls of the comb teeth is g, and the thickness of the comb teeth is h. The unitary unit comprising a comb pair includes two tip capacitance C _// and sidewall capacitance C _⊥. Is the sum of these

Is the capacitance per unit. If the number of comb teeth pairs is N, the total generated force can be expressed as follows.

When the voltage is constant, the force in the x direction can be expressed as follows.

を満たし、以下の近似が得られる。

Since the comb teeth are usually long and narrow, the gap between the side walls is designed to be narrow.

And the following approximation is obtained.

As described above, from the formula (8), the force acting on the comb teeth does not depend on the position x of the movable electrode. That is, the equivalent spring constant k _e for the small displacement Δx from the value of equation (8) obtained by differentiating at x, it can be seen that zero. That is, the AC voltage applied for exciting the vibrator 20 hardly changes the resonance frequency. For this reason, it does not hinder measurement of the voltage which is a measuring object.

  Next, the stopper 70 will be described in more detail. FIG. 9 is an enlarged view showing the contact portion 73 of the stopper 70 shown in FIG. 2 and its periphery. FIG. 9A shows a case where the voltage V to be measured is 0 V, and FIG. (C) shows the case where the voltage V to be measured is 147V, and (d) shows the case where the voltage V to be measured is 150V.

  As shown in FIG. 9A, when the voltage to be measured is 0 V, the distance between the contact portion 73 and the vibrator 20 is separated by L1. On the other hand, as shown in FIGS. 9B and 9C, when the voltage to be measured is increased, the vibrator 20 is pulled to the fixed electrode 30 side by electrostatic attraction, so that the contact portion 73 and the vibration are vibrated. The distance from the child 20 is gradually shortened to L2 and L3. Then, as shown in FIG. 9D, when the voltage to be measured reaches 150 V, the contact portion 73 comes into contact with the vibrator 20. Note that, as described above, the stopper 70 is not electrically connected anywhere, and the contact portion 73 protrudes toward the vibrator 20 from the fixed electrode 30, so that the vibrator 20 and the fixed electrode 30 Will be prevented and a short circuit will be prevented.

  FIG. 10 is a graph showing the correlation between the voltage V to be measured and the gap g between the vibrator 20 and the fixed electrode 30. As shown in FIG. 10, the gap g decreases as the voltage V to be measured increases. When the voltage V to be measured reaches 150 V, the gap g becomes a little over 10 μm, and the vibrator 20 comes into contact with the contact portion 73 of the stopper 70. Therefore, the voltage sensor 1 in this example can be measured when the voltage V to be measured is 147 V or less. In this example, when the voltage V to be measured is 150 V or higher, measurement is impossible, but a voltage of 150 V or higher can also be measured by various methods such as increasing the gap g in advance.

  Next, a modification of the voltage sensor 1 according to this embodiment will be described. FIG. 11 is a cross-sectional view showing a first modification of the voltage sensor 1 according to this embodiment. FIG. 11 schematically shows the electrical connection relationship.

  As shown in FIG. 11, the fixed electrode 30 and the driving electrode 50 of the voltage sensor 1 according to the first modification are configured to be surrounded by insulating layers 31 and 52 on a silicon substrate.

  Further, the vibrator 20 of the voltage sensor 1 according to the first modification also has a structure in which the periphery thereof is covered with the insulating layer 22. For this reason, by adopting the above configuration instead of the stopper 70, even if these electrodes 20, 30, 50 come into contact with each other, a short circuit can be prevented and safety can be improved.

  FIG. 12 is a cross-sectional view showing a second modification of the voltage sensor 1 according to this embodiment. FIG. 12 also schematically shows the electrical connection relationship.

  As shown in FIG. 12, the voltage sensor 1 according to the second modification is the same as that shown in FIG. 11, but is different in that an insulating layer 20 a is provided inside the vibrator 20. That is, the vibrator 20 according to the second modification has two electrode portions 20b and 20c separated by the insulating layer 20a, and the first electrode portion 20b is disposed on the drive electrode 50 side, The second electrode portion 20c is disposed on the fixed electrode 30 side.

  For this reason, the first electrode part 20b on the AC voltage side is insulated from the second electrode part 20c on the DC voltage side to be measured, and the high voltage system to be measured is electrically insulated from the drive side. To increase safety.

  FIG. 13 is a cross-sectional view illustrating a third modification of the voltage sensor 1 according to the present embodiment. Note that FIG. 13 also schematically shows the electrical connection relationship.

  As shown in FIG. 13, the voltage sensor 1 according to the third modification has an insulating layer 20a inside the vibrator 20 similar to that shown in FIG. An electrode part may be formed and may be separated vertically by the insulating layer 20a. That is, the vibrator 20 according to the third modification has two electrode parts 20b and 20c that are vertically separated by the insulating layer 20a, and the first electrode part 20b is disposed on the driving electrode 50 side. The second electrode portion 20c is disposed on the fixed electrode 30 side.

  For this reason, the first electrode part 20b on the AC voltage side is insulated from the second electrode part 20c on the DC voltage side to be measured, and the high voltage system to be measured is electrically insulated from the drive side. To increase safety.

  FIG. 14 is a cross-sectional view showing a fourth modification of the voltage sensor 1 according to this embodiment. FIG. 14 schematically shows the electrical connection relationship. In order to measure the amplitude of the vibrator 20, an electric signal may be taken out from the vibrator 20. For this reason, as shown in FIG. 14, the voltage sensor 1 according to the fourth modification includes an amplitude detection unit 80 that is electrically connected to the vibrator 20 and detects the amplitude of the vibrator 20.

  Here, the AC voltage applied to the vibrator 20 is generally classified on the low voltage side, and the amplitude detecting means 80 is also classified on the low voltage side. On the other hand, the voltage to be measured is classified on the high voltage side. For this reason, it is preferable that the low voltage side and the high voltage side are electrically separated.

  Therefore, the voltage sensor 1 according to the fourth modification includes an insulating unit 81 in front of the amplitude detecting unit 80. That is, an insulating means 81 is interposed between the vibration electrode 20 and the amplitude detection means 80 shown in FIG. 14, and the amplitude detection is performed even if the vibration electrode 20 contacts the fixed electrode 30 to which the DC voltage to be measured is applied. A high voltage is prevented from being applied to the means 80. As a result, the DC component can be cut off while passing only the AC signal for detecting the amplitude, and the amplitude detecting means 80 is insulated from the DC component of the high voltage system to be measured to further increase the safety. be able to. The insulating means 81 may be a capacitor by electrostatic coupling, a coil by inductive coupling, an LED (Light Emitting Diode) by optical coupling, or the like, and may be externally attached or incorporated in the sensor.

  FIG. 15 is a cross-sectional view illustrating a fifth modification of the voltage sensor 1 according to the present embodiment. FIG. 15 schematically shows the electrical connection relationship. As described with reference to FIG. 14, the AC voltage applied to the drive electrode 50 is generally classified into the low voltage side, and the voltage to be measured is electrically separated from the high voltage side. Is preferred.

  Therefore, the voltage sensor 1 according to the fifth modification includes an insulating unit 81 as in the fourth modification. The insulating means 81 is interposed between the driving electrode 50 and the AC generating circuit shown in FIG. 15, and even if the vibrating electrode 20 contacts the fixed electrode 30 to which the DC voltage to be measured is applied. A high voltage is prevented from being applied to the generation circuit. As a result, the DC component can be cut off while passing only the AC signal for exciting the vibrator 20, and the AC generator circuit is insulated from the DC component of the high voltage system to be measured for further safety. Can be increased. The insulating means 81 may be a capacitor by electrostatic coupling, a coil by inductive coupling, an LED (Light Emitting Diode) by optical coupling, or the like, and may be externally attached or incorporated in the sensor.

  In this way, according to the voltage sensor 1 according to the present embodiment, the voltage to be measured is applied to the fixed electrode 30 that is disposed to face the gap 20 in the vibrator 20 that is supported by the mechanical suspension 10. As a result, an electrostatic attractive force is applied to the vibrator 20 and the resonance frequency of the vibrator 20 is thereby changed, whereby the voltage to be measured is calculated. Here, when a voltage to be measured is applied to the fixed electrode 30, the spring constant of the suspension 10 substantially changes due to the electrostatic attractive force caused by this voltage, and the resonance frequency of the vibrator 20 changes. It becomes. Since this change has a certain correlation with the magnitude of the voltage to be measured, the value of the voltage to be measured can be measured from the changed resonance frequency. As described above, in the present invention, it is not necessary to use a high-precision resistor, the accuracy of voltage measurement can be improved, and an insulating means or the like is not necessary, and an increase in the number of parts can be suppressed. Further, since the measurement is performed by using the electrostatic attractive force that generates the voltage to be measured, the voltage can be measured with almost no current flowing from the measurement target. In addition, it is not necessary to use a magnetic collecting core or the like, optical components can be suppressed, an increase in power consumption and an increase in the number of components can be suppressed, and complicated assembly can also be suppressed.

  Further, since the mechanical stopper 70 or the insulators 22 and 31 are provided so that the vibrator 20 and the fixed electrode 30 are not short-circuited, a short-circuit between the vibrator 20 and the fixed electrode 30 is prevented, and safety can be improved. it can.

  Further, since the relationship between the vibrator 20 and the fixed electrode 30 is a parallel plate electrode, the gap dependency of the force acting between the electrodes is high. In addition, the slope of the electrostatic attraction with respect to the gap change becomes an equivalent spring constant for the electrostatic attraction. By applying the voltage to be measured, the total equivalent spring constant including the suspension changes, and the resonance frequency changes. The frequency is an amount that can be measured accurately, which can improve the measurement resolution. .

  In addition, electrostatic attraction is used to excite the vibrator 20. Since the resonance frequency can be measured even with a small vibration amplitude, a low voltage at which the electronic circuit operates can be used. Therefore, it is suitable for digitizing a voltage sensor.

  Further, since the electrodes for exciting the vibrator 20 are the comb-tooth electrodes 21 and 51, even if the vibrator 20 is moved by electrostatic attraction, the comb-tooth electrodes 21 and 51 have a small gap dependency and an alternating current. The influence on the resonance frequency due to the application of voltage can be reduced.

  Further, since the insulation means 81 for preventing the DC voltage to be measured from being applied to the amplitude detection means 80 is provided, the amplitude detection means 80 is electrically insulated from the DC component of the high voltage system to be measured. Safety can be further improved.

  In addition, since the insulation means 81 for preventing the DC voltage to be measured from being applied to the AC generation circuit is provided, the AC generation circuit is further electrically insulated from the DC component of the high voltage system to be measured. Safety can be increased.

  As described above, the present invention has been described based on the embodiment, but the present invention is not limited to the above embodiment, and may be modified without departing from the gist of the present invention.

  For example, in the present embodiment, the driving electrode 50 and the vibrator 20 include the comb electrodes 21 and 51. However, the present invention is not limited thereto, and the vibrator 20 can be vibrated by sufficiently generating an electrostatic attractive force. If possible, the comb electrodes 21 and 51 may not be particularly provided.

  Further, in the present embodiment, the suspension 10 has a shape folded back in a U-shape, but is not limited to this, and may be configured in other shapes such as a straight line.

DESCRIPTION OF SYMBOLS 1 ... Voltage sensor 10 ... Suspension 11 ... 1st suspension 11a ... 1st suspension part 11b ... 2nd suspension part 11c ... Flat plate 12 ... 2nd suspension 12a ... 1st suspension part 12b ... 2nd suspension part 12c ... Flat plate 20 ... Vibration electrode 20a ... insulating layer 20b ... first electrode part 20c ... second electrode part 21 ... comb electrode 22 ... insulating layer 30 ... fixed electrode 31 ... insulating layer 40 ... calculation unit 50 ... driving electrode 51 ... comb teeth Electrode 52 ... Insulating layer 61 ... First electrode 62 ... Second electrode 70 ... Stopper 71 ... Main part 72 ... Spring part 73 ... Contact part 80 ... Amplitude detecting means 81 ... Insulating means

Claims (9)

A vibrator supported by a mechanical suspension;
A driving electrode for vibrating the vibrator;
A fixed electrode disposed oppositely through a gap in the vibrator,
By applying a voltage to be measured to the fixed electrode, an electrostatic attraction is applied to the vibrator, and the voltage to be measured is determined from the resonance frequency of the vibrator that is changed by the action of the electrostatic attraction. A voltage sensor for calculating
The fixed electrode is provided on an insulating layer on a substrate such as silicon,
The vibrator is fixed on the substrate in a floating structure , connected to the other end of a suspension formed on the substrate and having one end connected to an electrode different from the fixed electrode and the driving electrode. ,
The drive electrode is disposed on the substrate so as to face the vibrator, and is disposed in parallel to the substrate together with the fixed electrode and the vibrator. The voltage sensor according to claim 1,
The voltage sensor, wherein the vibrator has an elongated shape. In the voltage sensor according to claim 1 or 2,
Each of the suspensions has a shape that is folded in a U-shape. The voltage sensor according to any one of claims 1 to 3,
A voltage sensor comprising a mechanical stopper or an insulator so that the vibrator and a fixed electrode to which a voltage to be measured is applied are not short-circuited. The voltage sensor according to any one of claims 1 to 4, wherein:
A voltage sensor, wherein a relationship between the vibrator and the fixed electrode to which a voltage to be measured is applied is a parallel plate electrode. The voltage sensor according to any one of claims 1 to 5,
A voltage sensor using electrostatic attraction to excite the vibrator. The voltage sensor according to claim 6, wherein
An electrode for exciting the vibrator is a comb-teeth electrode. The voltage sensor according to any one of claims 1 to 7,
Amplitude detection means for detecting the amplitude of the vibrator electrically connected to the vibrator;
Insulating means for preventing a voltage to be measured applied to the fixed electrode from being applied to the amplitude detecting means;
A voltage sensor comprising: The voltage sensor according to any one of claims 1 to 8,
The vibrator is
A first electrode portion connected to an alternating current generating circuit electrically connected to the vibrator and applying an alternating voltage to the vibrator;
A second electrode portion electrically connected to the fixed electrode;
Insulating means for insulating the first electrode portion and the second electrode portion;
Preventing the voltage to be measured applied to the fixed electrode by the insulating means from being applied to the AC generating circuit;
A voltage sensor characterized by that.

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