JP2011108989A - Variable capacitor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To reduce such an effect that drive noise caused by an AC drive signal gives to an object signal which is changed according to an electrostatic capacity change in an MEMS variable capacitor. <P>SOLUTION: The MEMS variable capacitor has such a configuration that a drive part 2 which is composed of a fixed electrode 21 and a movable electrode 23 in pairs and where the movable electrode 23 is oscillated to be driven by a drive signal and a capacitor 3 composed of the fixed electrode 31 and the movable electrode 33 in pairs are not only separately formed as an independent body but also disposed on a substrate 1 isolated from each other. Furthermore, the drive movable electrode 23 and the capacitor movable electrode 33 are connected to each other by a supporting beam 4 having electric insulating characteristics. The capacitor movable electrode 31 is oscillated to be driven so that the electrostatic capacitance of the capacitor 3 is changed by transmitting oscillating energy generated in the drive movable electrode 23 to a capacitor movable electrode 31 through the supporting beam portion 4. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a variable capacitor using MEMS (Micro Electro Mechanical Systems) technology.

  The MEMS technology is a technology for manufacturing a device that performs mechanical operation by integrating mechanical element parts, sensors, actuators, electronic circuits and the like on one substrate by a semiconductor process. For example, an acceleration sensor, a pressure sensor, a tactile sensor, It is applied to inertial sensors. Moreover, the variable capacitor which applied the MEMS technique is also implement | achieved (for example, refer patent documents 1-3).

  Conventionally, as a variable capacitor, a varactor diode that changes a capacitance using a semiconductor PN junction structure has been widely used. While this varactor diode cannot avoid the influence of shot noise caused by a PN junction, the MEMS variable capacitor that changes the capacitance by mechanical operation has an advantage that the influence of this noise can be suppressed. For this reason, MEMS variable capacitors are frequently used in the field of communication equipment including mobile phones.

Japanese Patent No. 3696193 Japanese Patent No. 3712123 JP 2006-93463 A

Japan Society of Mechanical Engineers "Nonlinear Dynamics-Introduction to Analysis of Nonlinear Phenomena" Corona (2007/7/1) P23 ~

  As a method for driving the MEMS variable capacitor, as disclosed in the cited documents 1 to 3, there is a method in which a DC voltage is applied to the piezoelectric actuator to deform it and the capacitance of the capacitor is steadily changed. Are known. In addition to this, the movable electrode is periodically vibrated by applying a periodically changing drive signal to a drive unit composed of a pair of a fixed electrode and a movable electrode, and the movable electrode of the capacitor is vibrated by this vibration. There is a method of periodically changing the capacitance.

  When the drive unit is driven to vibrate according to the latter method, it is necessary to apply an AC drive signal having an amplitude of about 5 V at the minimum. However, when the drive unit is driven to vibrate with an AC drive signal, electromagnetic drive noise due to the AC drive signal is generated, unlike when a DC voltage is applied. When this driving noise propagates to the capacitor side, this driving noise is superimposed on the electrical signal to be processed by the capacitor.

  When a general electric signal having a relatively large voltage with respect to the driving noise is handled, the influence of the driving noise is slight, but it is about several tens of μV to several hundred mV, which is handled in a communication field or a field where a living body is a measurement target. When an electric signal is a target, the drive noise has a relatively high potential with respect to the target signal. For this reason, there is a problem of a reduction in the signal-to-noise ratio in the variable capacitor, or an increase in circuit scale accompanying an increase in the filter circuit for reducing drive noise.

  In particular, in the conventional MEMS variable capacitor, the driving unit and the movable electrode of the capacitor unit that moves in conjunction with the driving unit are integrally configured, and driving noise caused by the AC driving signal is electrically propagated to the capacitor side. The effect of driving noise becomes remarkable.

  The present invention has been made to solve the above-mentioned problem, and in a MEMS variable capacitor, for reducing the influence of drive noise caused by an AC drive signal on a target signal that changes with a change in capacitance of the capacitor. The purpose is to provide technology.

  The variable capacitor according to claim 1, wherein the variable capacitor according to claim 1, wherein the driving unit and the movable electrode of the capacitor unit are formed as separate bodies separated from each other and disposed on the substrate apart from each other. In addition, the driving part and the movable electrode of the capacitor part are connected to each other via a support beam having an electrical insulating structure for insulating.

  By adopting a structure in which the driving part and the movable electrode of the capacitor part are formed separately from each other and separated from each other, both are electrically separated, so that electromagnetic driving noise generated in the driving part is not generated. It is difficult to spread to the capacitor portion, and the influence of driving noise can be reduced.

  Further, a structure is adopted in which the drive unit and the movable electrode of the capacitor unit are connected by a support beam having an electrically insulating structure, and vibration energy generated in the drive unit is transmitted to the capacitor unit via the support beam. By providing the support beam, the drive unit and the capacitor unit can be vibrated at different frequencies due to differences in the natural frequencies of the drive unit, the support beam, and the movable electrode of the capacitor unit. Thereby, the frequency of the drive noise and the operating frequency of the capacitor unit can be changed within a certain range, and the drive noise that spreads to the capacitor unit beyond the distance between the drive unit and the capacitor unit, and the capacitor unit It is possible to easily separate the electrical signal (target signal) to be processed by. As a result, the influence of drive noise on the target signal can be reduced.

  As an example of theoretical support for the operation of the drive unit and the capacitor unit in different periods, Non-Patent Document 1 describes a nonlinear phenomenon that resonates at a period of 1/3, 1/5, etc. of the original frequency. Is described.

  Furthermore, as described in claim 2, it is preferable to design the movable electrode and the drive unit of the capacitor unit as members having different natural frequencies. By doing so, the drive unit and the capacitor unit can be vibrated at different frequencies due to the difference in natural frequency between the drive unit and the movable electrode of the capacitor unit, and the drive noise and the target signal of the capacitor unit can be vibrated. And can be easily separated. As a result, the influence of drive noise on the target signal can be reduced more effectively.

  More specifically, as described in claim 3, the movable electrode and the drive unit of the capacitor unit are different from each other by being formed so as to be different from each other in cross-sectional shape, length or width, or material. It may be configured to have a natural frequency. The natural frequency of an object is determined by various characteristics such as shape properties such as the length, width, and cross-sectional shape of the object, or the material of the electrode material itself such as density and Young's modulus. Therefore, by setting these specifications as appropriate, it is possible to design the movable electrode of the capacitor unit and the natural frequency of the drive unit to be different from each other. In addition, regarding the specific design, the natural frequency of the drive unit and the capacitor unit is set so that the capacitor unit vibrates at the operating frequency according to the purpose of use of the variable capacitor, and the natural frequency is set. The specifications of the drive unit and the capacitor unit may be designed according to the above.

  Next, the variable capacitor according to claim 4 is characterized in that the support beam connecting the driving unit and the movable electrode of the capacitor unit is fixed to the substrate with a space between the substrate and the substrate. By doing in this way, the vibration energy of a drive part can be efficiently transmitted to a capacitor part.

  On the other hand, in the variable capacitor according to claim 5, the drive unit and the movable electrode of the capacitor are formed as separate bodies separated from each other and disposed on the substrate so as to be separated from each other. In addition, an electrically insulating fluid that transmits vibration of the drive unit is interposed between the drive unit and the movable electrode of the capacitor.

  By adopting a structure in which the driving part and the movable electrode of the capacitor part are formed separately from each other and separated from each other, both are electrically separated, so that electromagnetic driving noise generated in the driving part is not generated. It is difficult to spread to the capacitor portion, and the influence of driving noise can be reduced.

  Furthermore, an electrically insulating fluid is interposed between the drive unit and the movable electrode of the capacitor unit, and a structure is adopted in which vibration energy generated in the drive unit is transmitted to the capacitor unit using the viscosity of the fluid. By doing in this way, a drive part and a capacitor part can be vibrated by another frequency by the difference in each natural frequency of a drive part and the movable electrode of a capacitor part. Thereby, the frequency of the drive noise and the operating frequency of the capacitor unit can be changed within a certain range, and the drive noise that spreads to the capacitor unit beyond the distance between the drive unit and the capacitor unit, and the capacitor unit Can be easily separated from the target signal. As a result, the influence of drive noise on the target signal can be reduced.

  In addition, as an electrically insulating fluid interposed between the drive unit and the movable electrode of the capacitor unit, either gas or liquid may be used. In the case of gas, for example, it may be possible to use air or a gas composed of a specific component. In the case of a liquid, for example, it is conceivable to use insulating oil, inert liquid, other insulating liquid, or the like.

  Furthermore, as described in claim 8, the movable electrode and the drive unit of the capacitor unit may be designed to be formed as members having different natural frequencies. More specifically, as described in claim 9, the movable electrode of the capacitor unit and the driving unit are formed so as to be different from each other in at least one of a cross-sectional shape, a length or width, a height, and a material. It is good to comprise so that it may have a mutually different natural frequency.

  By doing so, the drive unit and the capacitor unit can be vibrated at different frequencies due to the difference in natural frequency between the drive unit and the movable electrode of the capacitor unit, and the drive noise and the target signal of the capacitor unit And can be easily separated. As a result, the influence of drive noise on the target signal can be reduced more effectively. For specific design, the natural frequency of the drive unit and the capacitor unit is set so that the capacitor unit vibrates at the operating frequency according to the purpose of use of the variable capacitor. The specifications of the drive unit and the capacitor unit may be designed according to the above.

It is a figure which shows the structure of the variable capacitor of 1st Embodiment. It is a figure which shows the structure of the variable capacitor of 2nd Embodiment. It is a figure which shows the structure of the variable capacitor of 3rd Embodiment. It is a figure which shows the structure of the variable capacitor of 4th Embodiment. It is a figure which shows the structure of the variable capacitor of 5th Embodiment. It is a figure which shows the structure of the variable capacitor of 6th Embodiment.

Hereinafter, embodiments of the present invention will be described with reference to the drawings. In addition, this invention is not limited to the following embodiment at all, and can be implemented in various aspects.
[First Embodiment]
FIG. 1A is a top view of the variable capacitor according to the first embodiment, and FIG. 1B is a side view from the direction A of FIG. 1A.

  As shown in FIG. 1A, on the substrate 1 formed of an insulating material such as silicon or glass, a driving unit 2 and a capacitor unit 3 formed separately from each other are arranged along the X-axis direction in the drawing. Are arranged in parallel. Further, a support beam portion 4 and an insulating layer 5 for supporting the driving portion 2 and the capacitor portion 3 are formed on the substrate 1. Furthermore, an electric circuit for applying an AC drive signal is connected to the two electrodes 21 and 23 constituting the drive unit 2, and a control object is connected to the two electrodes 31 and 33 constituting the capacitor unit 3. The electrical circuit connecting to the electronic circuit is connected.

  The drive unit 2 is a mechanical element component for generating vibration energy necessary to change the capacitance of the capacitor unit 3, and includes a drive unit fixed electrode 21 and a drive unit that are two electrodes arranged in parallel to each other. The movable part electrode 23 and the driving part movable electrode 23 are formed integrally with a support damper 25 that supports the movable part electrode 23. The drive unit fixed electrode 21 is a non-movable electrode fixed to at least one of the substrate 1 and the insulating layer 5, and one of the electric paths from the drive signal source is connected thereto. On the other hand, the drive unit movable electrode 23 is not fixed to the substrate 1, and the upper end side in the Y-axis direction is supported by the insulating layer 5 by the elastic support damper 25, and the lower end side in the Y-axis direction has insulation. It is fixed to the support beam 4. The support damper 25 supports the drive unit movable electrode 23 so as to move elastically, and limits the vibration mode of the drive unit movable electrode 23 to a necessary specific mode. Further, the other electric circuit from the drive signal source is connected, and also serves as an electric circuit for applying the drive signal to the drive unit movable electrode 23.

  The driving unit fixed electrode 21 and the driving unit movable electrode 23 are integrally formed with a plurality of comb-tooth portions 22 and 24 on the side facing the mating electrode so as not to contact the comb-tooth portion of the mating electrode. It is located in a staggered position to face each other. Thus, the drive unit fixed electrode 21 and the drive unit movable electrode 23 each have a comb-tooth structure, and these comb-tooth structures face each other, thereby increasing the capacitance between the two electrodes. .

  When an alternating drive signal is applied between the two electrodes 21 and 23 of the drive unit 2, an electrostatic force (attractive force) that periodically changes according to the waveform of the drive signal acts between the two electrodes 21 and 23. At this time, due to the periodically changing electrostatic force and the elastic restoring force of the support damper 25 and the drive unit movable electrode 23 itself, the drive unit movable electrode 23 moves in the X-axis direction according to the cycle of the drive signal. Vibrate. The drive unit 2 drives the capacitor unit 3 to vibrate by the vibration energy thus generated.

  The capacitor unit 3 includes a capacitor fixed electrode 31 and a capacitor movable electrode 33 that are two electrodes arranged in parallel to each other, and a support damper 35 that is integrally formed with and supports the capacitor movable electrode 33. . The capacitor fixed electrode 31 is a non-movable electrode fixed to at least one of the substrate 1 and the insulating layer 5, and one of the electric paths leading to the electronic circuit to be controlled is connected. On the other hand, the capacitor movable electrode 33 is not fixed to the substrate 1, the upper end in the Y-axis direction is supported by the insulating layer 5 by the elastic support damper 35, and the lower end in the Y-axis direction has an insulating support beam. It is fixed to the part 4. The support damper 35 supports the capacitor movable electrode 33 so as to move elastically, and limits the vibration mode of the capacitor movable electrode 33 to a necessary specific mode. The other electric circuit leading to the electronic circuit to be controlled is connected, and also serves as an electric circuit for applying the electric signal to be processed to the capacitor movable electrode 33.

  The capacitor fixed electrode 31 and the capacitor movable electrode 33 are integrally formed with a plurality of comb teeth 32 and 34 on the side facing the counterpart electrode, respectively, so that they do not contact the comb teeth of the counterpart electrode. It is located at the opposite side. As described above, the capacitor fixed electrode 31 and the capacitor movable electrode 33 each have a comb-tooth structure, and these comb-tooth structures face each other, thereby increasing the capacitance between the two electrodes.

  The drive part movable electrode 23 and the capacitor movable electrode 33 are connected by a support beam part 4 having electrical insulation. Thereby, the vibration energy generated in the drive unit movable electrode 23 by the drive signal propagates to the capacitor movable electrode 33 through the support beam unit 4. Therefore, the capacitor movable electrode 33 receives the vibration energy from the drive unit movable electrode 23 and is driven to vibrate in the X-axis direction. Since the capacitor movable electrode 33 vibrates, the distance between both the capacitor fixed electrode 31 and the capacitor movable electrode 33 changes according to the vibration, so that the capacitance of the capacitor unit 3 periodically changes. In this state, when a target signal is applied between both electrodes from the electronic circuit side, it can be extracted as a change in signal waveform proportional to the change in capacitance.

  The support beam portion 4 is made of an electrically insulating material, connects the drive portion movable electrode 23 and the capacitor movable electrode 33, and ensures insulation between the electrodes. Further, as shown in FIG. 1B, both ends of the support beam portion 4 are fixed on the substrate 1 so that the central portion is lifted from the substrate 1, and a space 40 is formed between the support beam portion 4 and the substrate 1. The beam structure is formed. With this beam structure, vibration energy generated in the drive unit movable electrode 23 can be efficiently transmitted to the capacitor movable electrode 33.

  On the other hand, the drive unit movable electrode 23 and the capacitor movable electrode 33 are formed as members having different natural frequencies. Specifically, at least one of the specifications that determine the natural frequency of the object, such as the shape properties such as the length, width, and cross-sectional shape of the electrode, or the material of the electrode material itself, such as density and Young's modulus, is different from each other. By forming in this way, different natural frequencies can be given. In addition, regarding the specific design, the natural frequency of the drive unit movable electrode 23 and the capacitor movable electrode 33 is set so that the capacitor movable electrode 33 vibrates at an operating frequency according to the purpose of use of the variable capacitor. What is necessary is just to design each item of both electrodes 23 and 33 according to the natural frequency. Further, depending on the setting of the natural frequency, the capacitor movable electrode 33 can be operated on the low frequency side or the high frequency side with respect to the frequency of the drive signal.

  According to the variable capacitor of the present embodiment having the above-described configuration, the drive unit 2 and the capacitor unit 3 are formed as separate bodies that are separated from each other, and by adopting a structure separated from each other, both are electrically Therefore, the electromagnetic drive noise generated in the drive unit 2 is less likely to spread to the capacitor unit 3, and the influence of the drive noise can be reduced. Furthermore, the drive unit movable electrode 23 and the capacitor movable electrode 33 can be vibrated at different frequencies due to differences in the natural frequencies of the drive unit movable electrode 23, the capacitor movable electrode 33, and the support beam unit 4. And the target signal of the capacitor unit 3 can be easily separated. As a result, the influence of drive noise on the target signal can be reduced more effectively.

  Further, in this configuration, in order to prevent the drive signal voltage from being superimposed on the circuit signal through the support beam portion 4 and the insulating layer 5 due to capacitive coupling, the drive portion 2 side and the inside of the support beam portion 4 and the insulating layer 5 are provided. You may provide the GND electrode surface which divides | segments from the capacitor | condenser part 3 side. Thereby, the electric noise which propagates the inside of the support beam part 4 and the insulating layer 5 by capacitive coupling can be shielded.

[Second Embodiment]
FIG. 2A is a top view of the variable capacitor according to the second embodiment, and FIG. 2B is a cross-sectional view taken along line AA ′ of FIG. In addition, the same code | symbol is attached | subjected here about the component similar to the component of above-mentioned embodiment. Moreover, the description below is abbreviate | omitted about the matter which the above-mentioned embodiment and description content overlap.

  As shown in FIG. 2A, on the substrate 1, a drive unit 2 and a capacitor unit 3 formed separately from each other are arranged in a column along the Y-axis direction in the drawing. That is, the positional relationship between the drive unit 2 and the capacitor unit 3 is different from that of the first embodiment, and the other configurations are common. On the substrate 1, a support beam portion 4 that connects the drive unit movable electrode 23 and the capacitor movable electrode 33 is formed between the drive unit 2 and the capacitor unit 3. In addition, an insulating layer 51 for supporting the drive unit 2 is formed on the upper end side in the Y-axis direction of the drive unit 2, and in order to support the capacitor unit 3 on the lower end side in the Y-axis direction of the capacitor unit 3. Insulating layer 52 is formed.

  The drive unit fixed electrode 21 is fixed to at least one of the substrate 1 and the insulating layer 51 and is immovable. On the other hand, the drive unit movable electrode 23 is not fixed to the substrate 1, the upper end side in the Y-axis direction is supported by the insulating layer 51 by the support damper 25, and the lower end side in the Y-axis direction is fixed to the support beam unit 4. Yes. When an alternating drive signal is applied between the two electrodes 21 and 23 of the drive unit 2, due to the periodically changing electrostatic force and the restoring force due to the elasticity of the support damper 25 and the drive unit movable electrode 23 itself, The drive unit movable electrode 23 vibrates in the X-axis direction in the figure according to the cycle of the drive signal. The drive unit 2 drives the capacitor unit 3 to vibrate by the vibration energy thus generated.

  The capacitor fixed electrode 31 is fixed to at least one of the substrate 1 and the insulating layer 52 and is immovable. On the other hand, the capacitor movable electrode 33 is not fixed to the substrate 1, the lower end side in the Y-axis direction is supported by the insulating layer 52 by the support damper 35, and the upper end side in the Y-axis direction is fixed to the support beam portion 4. .

  The drive unit movable electrode 23 and the capacitor movable electrode 33 are connected to each other by being fixed to both side surfaces of the support beam unit 4 in the X-axis direction. Thereby, the vibration energy generated in the drive unit movable electrode 23 by the drive signal propagates to the capacitor movable electrode 33 through the support beam unit 4. Therefore, the capacitor movable electrode 33 is oscillated and driven by receiving the vibration energy from the drive unit movable electrode 23, and the capacitance of the capacitor unit 3 periodically changes according to the vibration. In this state, when a target signal is applied between both electrodes from the electronic circuit side, it can be extracted as a change in signal waveform proportional to the change in capacitance.

  The support beam portion 4 is made of an electrically insulating material, connects the drive portion movable electrode 23 and the capacitor movable electrode 33, and ensures insulation between the electrodes. 2B, both ends of the support beam portion 4 are fixed on the substrate 1 so that the central portion is lifted from the substrate 1, and a space 40 is formed between the support beam portion 4 and the substrate 1. The beam structure is formed. With this beam structure, vibration energy generated in the drive unit movable electrode 23 can be efficiently transmitted to the capacitor movable electrode 33.

  On the other hand, the drive unit movable electrode 23 and the capacitor movable electrode 33 are formed as members having different natural frequencies. Specifically, at least one of the specifications that determine the natural frequency of the object, such as the shape properties such as the length, width, and cross-sectional shape of the electrode, or the material of the electrode material itself, such as density and Young's modulus, is different from each other. By forming in this way, different natural frequencies can be given.

  Further, in this configuration, in order to prevent the drive signal voltage from being superimposed on the circuit signal through the support beam portion 4 due to capacitive coupling, the GND that divides the drive portion 2 side and the capacitor portion 3 side inside the support beam portion 4. An electrode surface may be provided. Thereby, the electric noise which propagates the inside of the support beam part 4 by capacitive coupling can be shielded.

[Third Embodiment]
FIG. 3A is an external perspective view of the variable capacitor according to the third embodiment. FIG. 3B is a top view of the variable capacitor drive unit 2 according to the third embodiment, and FIG. 3C is a top view of the capacitor unit 3. FIG. 3D is a cross-sectional view taken along line AA ′ of FIGS. 3B and 3C. In addition, the same code | symbol is attached | subjected here about the component similar to the component of above-mentioned embodiment. Moreover, the description below is abbreviate | omitted about the matter which the above-mentioned embodiment and description content overlap.

  In the variable capacitor according to the third embodiment, as shown in FIG. 3A, a layer constituting the driving unit 2 is formed on the substrate 1, and the capacitor unit 3 is further formed on the layer of the driving unit 2. Are formed.

  The drive unit 2 is a mechanical element part that drives the capacitor unit 3 stacked above, and as shown in FIG. 3B, the drive unit fixed electrode 21 and the drive unit movable electrode arranged in parallel to each other. 23 and a support bridge 26 that is formed integrally with the drive unit movable electrode 23 and supports it. The drive unit fixed electrode 21 is a non-movable electrode fixed to insulating layers 27 and 28 formed along the outer edge of the drive unit 2, and is disposed at the left end portion in the X-axis direction of the drive unit 2. In addition, one side of the electric circuit from the drive signal source is connected to the drive unit fixed electrode 21.

  On the other hand, the drive unit movable electrode 23 is disposed at the center of the drive unit 2 and is supported on the insulating layer 27 by support bridges 26 extending from the upper end side and the lower end portion in the Y-axis direction. The support bridge 26 supports the drive unit movable electrode 23 so as to move elastically. Further, the other electric circuit from the drive signal source is connected, and also serves as an electric circuit for applying the drive signal to the drive unit movable electrode 23. The driving unit fixed electrode 21 and the driving unit movable electrode 23 are integrally formed with a plurality of comb-tooth portions 22 and 24 on the side facing the mating electrode so as not to contact the comb-tooth portion of the mating electrode. It is located in a staggered position to face each other.

  When an alternating drive signal is applied between the two electrodes 21 and 23 of the drive unit 2, an electrostatic force (attractive force) that periodically changes according to the waveform of the drive signal acts between the two electrodes 21 and 23. At this time, the drive unit movable electrode 23 vibrates in the X-axis direction according to the cycle of the drive signal by the periodically changing electrostatic force and the restoring force due to the elasticity of the support bridge 26. The drive unit 2 drives the capacitor unit 3 to vibrate by the vibration energy thus generated.

  As shown in FIG. 3C, the capacitor unit 3 is formed integrally with the capacitor fixed electrode 31 and the capacitor movable electrode 33 and the capacitor movable electrode 33 which are arranged in parallel with each other, and the support bridge 36 which supports the capacitor fixed electrode 31 and the capacitor movable electrode 33. It consists of. The capacitor fixed electrode 31 is a non-movable electrode fixed to insulating layers 37 and 38 formed along the outer edge of the capacitor unit 3, and is disposed at the left end portion in the X-axis direction of the capacitor unit 3. The capacitor fixed electrode 31 is connected to one side of an electric circuit leading to the electronic circuit to be controlled.

  On the other hand, the capacitor movable electrode 33 is disposed at the center of the capacitor unit 3 and at a position overlapping the drive unit movable electrode 23 of the lower drive unit 2 when viewed from above the variable capacitor, and has an upper end and a lower end in the Y-axis direction. Are supported on the insulating layer 37 by supporting bridges 36 respectively extending from. The support bridge 36 supports the capacitor movable electrode 33 so as to move elastically. The other electric circuit leading to the electronic circuit to be controlled is connected, and also serves as an electric circuit for applying the electric signal to be processed to the capacitor movable electrode 33. The capacitor fixed electrode 31 and the capacitor movable electrode 33 are integrally formed with a plurality of comb teeth 32 and 34 on the side facing the counterpart electrode, respectively, so that they do not contact the comb teeth of the counterpart electrode. It is located at the opposite side.

  As shown in FIG. 3D, the drive unit movable electrode 23 and the capacitor movable electrode 33 are arranged so as to face each other with a certain space 6 therebetween. The space 6 is filled with an insulating fluid for transmitting vibration energy generated by the drive unit movable electrode 23. That is, the drive unit movable electrode 23 and the capacitor movable electrode 33 are separated from each other, and an insulating fluid layer is interposed between the electrodes. Thereby, the vibration energy generated in the drive unit movable electrode 23 by the drive signal propagates to the capacitor movable electrode 33 due to the viscosity of the insulating fluid. Therefore, the capacitor movable electrode 33 receives the vibration energy from the drive unit movable electrode 23 and is driven to vibrate in the X-axis direction. Since the capacitor movable electrode 33 vibrates, the distance between both the capacitor fixed electrode 31 and the capacitor movable electrode 33 changes according to the vibration, so that the capacitance of the capacitor unit 3 periodically changes. In this state, when a target signal is applied between both electrodes from the electronic circuit side, it can be extracted as a change in signal waveform proportional to the change in capacitance.

  As the insulating fluid filled between the drive unit movable electrode 23 and the capacitor movable electrode 33, either gas or liquid may be used. In the case of gas, for example, it may be possible to use air or a gas composed of a specific component. In the case of a liquid, for example, it is conceivable to use insulating oil, inert liquid, other insulating liquid, or the like.

  On the other hand, the drive unit movable electrode 23 and the capacitor movable electrode 33 are formed as members having different natural frequencies. Specifically, at least one of the specifications that determine the natural frequency of the object, such as the electrode properties such as the electrode properties themselves, such as the electrode properties themselves, such as the electrode properties themselves, such as the electrode properties themselves such as the length, width, height, and cross-sectional shape of the electrode. Can be given different natural frequencies.

  According to the variable capacitor of the present embodiment having the above-described configuration, the drive unit 2 and the capacitor unit 3 are formed as separate bodies that are separated from each other, and by adopting a structure separated from each other, both are electrically Therefore, the electromagnetic drive noise generated in the drive unit 2 is less likely to spread to the capacitor unit 3, and the influence of the drive noise can be reduced. Further, the drive unit movable electrode 23 and the capacitor movable electrode 33 are vibrated at different frequencies due to the difference in the natural frequency of the drive unit movable electrode 23, the capacitor movable electrode 33, and the insulating fluid interposed between the two electrodes. It is possible to easily separate the drive noise from the target signal of the capacitor unit 3. As a result, the influence of drive noise on the target signal can be reduced more effectively.

  Further, in this configuration, in order to prevent the drive signal voltage from being superimposed on the circuit signal through the insulating layers 37 and 38 due to capacitive coupling, the driving unit 2 side and the capacitor unit 3 side are respectively provided inside the insulating layers 37 and 38. A GND electrode surface to be divided may be provided. Thereby, the electric noise which propagates the inside of the insulating layers 37 and 38 by capacitive coupling can be shielded.

[Fourth Embodiment]
FIG. 4A is a top view of the variable capacitor according to the fourth embodiment, and FIG. 4B is a side view from the direction A of FIG. 4A. In addition, the same code | symbol is attached | subjected here about the component similar to the component of above-mentioned embodiment. Moreover, the description below is abbreviate | omitted about the matter which the above-mentioned embodiment and description content overlap.

  As shown in FIG. 4A, on the substrate 1, a drive unit 2 and a capacitor unit 3 formed separately from each other are arranged in parallel along the X-axis direction in the drawing. Among these, the capacitor unit 3 is provided with two fixed electrodes 31a and 31b on both sides in the left-right vibration direction of the capacitor movable electrode 33 that is driven to vibrate by the drive energy propagated from the drive unit 2, and one capacitor movable electrode. Two capacitors having 33 as a common electrode are formed. That is, the variable capacitor of the fourth embodiment is different from the first embodiment in that there are two capacitor fixed electrodes 31 that are paired with the capacitor movable electrode 33 in the capacitor unit 3, and the other configurations are common. .

  The capacitor fixed electrodes 31 a and 31 b are immovable electrodes fixed to at least one of the substrate 1 and the insulating layer 5. Each of the capacitor fixed electrodes 31a and 31b is connected to an electric circuit paired with the electric circuit connected to the capacitor movable electrode 33. The capacitor fixed electrodes 31 a and 31 b are integrally formed with a plurality of comb-tooth portions 32 a and 32 b on the side facing the capacitor movable electrode 33, and are similarly formed on both the left and right sides of the capacitor movable electrode 33. In order to avoid contact with the comb-teeth part 34, they are alternately positioned so as to face each other. Thus, the two capacitor fixed electrodes 31a and 31b and the capacitor movable electrode 33 each have a comb-tooth structure, and these comb-tooth structures face each other, so that both the fixed electrodes 31a and 31b and the capacitor movable electrode 33 are in contact with each other. The capacitance between each of them is increased.

  The vibration energy generated in the drive unit movable electrode 23 by the drive signal propagates to the capacitor movable electrode 33 through the support beam unit 4. As a result, the capacitor movable electrode 33 is driven to vibrate left and right in the X-axis direction. Since the distance between the fixed electrodes 31a and 31b and the movable capacitor electrode 33 changes according to the vibration of the movable capacitor electrode 33, the capacitances of the two capacitors formed by the fixed electrodes 31a and 31b and the movable capacitor electrode 33 are different. Each changes periodically. At this time, when the capacitance of one capacitor is a maximum, the capacitance of the other capacitor becomes a minimum, and so on, the changes in the capacitance of the two capacitors are in an opposite phase relationship.

  According to the configuration as described above, it is possible to configure a variable capacitor including two capacitors that operate differently depending on a single drive unit, which is efficient in applications that require a pair of variable capacitors that vary in opposite phases. Circuit design is possible.

  Further, as another contrivance, the driving unit fixed electrode 21 of the driving unit 2 and the capacitor fixing electrodes 31a and 31b of the capacitor unit 3 are each provided with a supporting beam portion so that the lower end portion in the Y-axis direction does not contact the supporting beam portion 4. 4 and spaced apart. With this configuration, vibration of the support beam 4 is not hindered by the fixed electrode, and vibration energy generated in the drive unit movable electrode 23 is efficiently transferred to the capacitor movable electrode 33 via the support beam 4. Can communicate. Such a configuration is particularly effective when the vibration energy generated in the drive unit movable electrode 23 is small.

  Further, in this configuration, in order to prevent the drive signal voltage from being superimposed on the circuit signal through the support beam portion 4 and the insulating layer 5 due to capacitive coupling, the drive portion 2 side and the inside of the support beam portion 4 and the insulating layer 5 are provided. You may provide the GND electrode surface which divides | segments from the capacitor | condenser part 3 side. Thereby, the electric noise which propagates the inside of the insulating layers 37 and 38 by capacitive coupling can be shielded.

[Fifth Embodiment]
FIG. 5A is a top view of the variable capacitor according to the fifth embodiment, and FIG. 5B is a side view from the direction A of FIG. 5A. In addition, the same code | symbol is attached | subjected here about the component similar to the component of above-mentioned embodiment. Moreover, the description below is abbreviate | omitted about the matter which the above-mentioned embodiment and description content overlap.

  As shown in FIG. 5A, on the substrate 1, a drive unit 2 and a capacitor unit 3 that are formed separately from each other are arranged in a column along the Y-axis direction in the drawing. Among these, the capacitor unit 3 is provided with two fixed electrodes 31a and 31b on both sides in the left-right vibration direction of the capacitor movable electrode 33 that is driven to vibrate by the drive energy propagated from the drive unit 2, and one capacitor movable electrode. Two capacitors having 33 as a common electrode are formed. That is, the variable capacitor of the fifth embodiment is different from the second embodiment in that there are two capacitor fixed electrodes 31 that are paired with the capacitor movable electrode 33 in the capacitor unit 3, and the other configurations are common. .

  The capacitor fixed electrodes 31a and 31b are fixed to at least one of the substrate 1 and the insulating layer 52 and are immovable. Each of the capacitor fixed electrodes 31a and 31b is connected to an electric circuit paired with the electric circuit connected to the capacitor movable electrode 33.

  The vibration energy generated in the drive unit movable electrode 23 by the drive signal propagates to the capacitor movable electrode 33 through the support beam unit 4. As a result, the capacitor movable electrode 33 is driven to vibrate left and right in the X-axis direction. Since the distance between the fixed electrodes 31a and 31b and the movable capacitor electrode 33 changes according to the vibration of the movable capacitor electrode 33, the capacitances of the two capacitors formed by the fixed electrodes 31a and 31b and the movable capacitor electrode 33 are different. Each changes periodically. At this time, when the capacitance of one capacitor is a maximum, the capacitance of the other capacitor becomes a minimum, and so on, the changes in the capacitance of the two capacitors are in an opposite phase relationship.

  In addition, the driving unit fixed electrode 21 of the driving unit 2 and the capacitor fixing electrodes 31a and 31b of the capacitor unit 3 are formed at a distance from the support beam unit 4 so that the ends thereof do not contact the support beam unit 4. Yes. Thereby, the vibration energy generated in the drive unit movable electrode 23 can be efficiently transmitted to the capacitor movable electrode 33 via the support beam unit 4.

  Further, in this configuration, in order to prevent the drive signal voltage from being superimposed on the circuit signal through the support beam portion 4 due to capacitive coupling, the GND that divides the drive portion 2 side and the capacitor portion 3 side inside the support beam portion 4. An electrode surface may be provided. Thereby, the electric noise which propagates the inside of the support beam part 4 by capacitive coupling can be shielded.

[Sixth Embodiment]
FIG. 6A is an external perspective view of the variable capacitor according to the sixth embodiment. FIG. 6B is a top view of the variable capacitor drive unit 2 of the sixth embodiment, and FIG. 6C is a top view of the capacitor unit 3. FIG. 6D is a cross-sectional view taken along line AA ′ of FIGS. 6B and 6C. In addition, the same code | symbol is attached | subjected here about the component similar to the component of above-mentioned embodiment. Moreover, the description below is abbreviate | omitted about the matter which the above-mentioned embodiment and description content overlap.

  In the variable capacitor of the sixth embodiment, as shown in FIG. 6A, a layer constituting the driving unit 2 is formed on the substrate 1, and the capacitor unit 3 is further formed on the layer of the driving unit 2. Are formed. Among these, the drive unit 2 whose details are shown in FIG. 6B is a mechanical element part for driving the capacitor unit 3 placed above, and has the same configuration as the drive unit 2 in the third embodiment. Have

  On the other hand, as shown in FIG. 6C, the capacitor unit 3 is provided with two fixed electrodes 31 a and 31 b on both sides in the left-right vibration direction of the capacitor movable electrode 33 that is driven to vibrate by the drive energy propagated from the drive unit 2. Two capacitors having one capacitor movable electrode 33 as a common electrode are configured. That is, the variable capacitor of the sixth embodiment is different from the third embodiment in that there are two capacitor fixed electrodes 31 that are paired with the capacitor movable electrode 33 in the capacitor unit 3, and the other configurations are common. .

  The capacitor fixed electrodes 31 a and 31 b are immovable electrodes fixed to insulating layers 37 and 38 formed along the outer edge of the capacitor unit 3, and are respectively disposed on both left and right ends in the X-axis direction of the capacitor unit 3. ing. Each of the capacitor fixed electrodes 31a and 31b is connected to an electric circuit paired with the electric circuit connected to the capacitor movable electrode 33. The capacitor fixed electrodes 31 a and 31 b are integrally formed with a plurality of comb-tooth portions 32 a and 32 b on the side facing the capacitor movable electrode 33, and are similarly formed on both the left and right sides of the capacitor movable electrode 33. In order to avoid contact with the comb-teeth part 34, they are alternately positioned so as to face each other.

  The vibration energy generated in the drive unit movable electrode 23 by the drive signal is propagated to the capacitor movable electrode 33 through the insulating fluid filled in the space 6 between the drive unit movable electrode 23 and the capacitor movable electrode. As a result, the capacitor movable electrode 33 is driven to vibrate left and right in the X-axis direction. Since the distance between the fixed electrodes 31a and 31b and the movable capacitor electrode 33 changes according to the vibration of the movable capacitor electrode 33, the capacitances of the two capacitors formed by the fixed electrodes 31a and 31b and the movable capacitor electrode 33 are different. Each changes periodically. At this time, when the capacitance of one capacitor is a maximum, the capacitance of the other capacitor becomes a minimum, and so on, the changes in the capacitance of the two capacitors are in an opposite phase relationship.

  Further, in this configuration, in order to prevent the driving signal voltage from being superimposed on the circuit signal through the insulating layer 38 due to capacitive coupling, the GND electrode surface that divides the driving unit 2 side and the capacitor unit 3 side inside the insulating layer 38. May be provided. Thereby, the electric noise which propagates the inside of the insulating layer 38 by capacitive coupling can be shielded.

  DESCRIPTION OF SYMBOLS 1 ... Board | substrate, 2 ... Drive part, 21 ... Drive part fixed electrode, 22 ... Comb tooth part, 23 ... Drive part movable electrode, 24 ... Comb tooth part, 25 ... Support damper, 26 ... Support bridge, 27, 28 ... Insulating layer, 3 ... Capacitor part 31, 31a, 31b ... Capacitor fixed electrode, 32, 32a, 32b ... Comb tooth part, 33 ... Capacitor movable electrode, 34 ... Comb tooth part, 35 ... Support damper, 36 ... Support Bridge, 37, 38 ... insulating layer, 4 ... support beam, 40 ... space, 5, 51, 52 ... insulating layer, 6 ... fluid layer.

Claims (9)

A capacitor unit composed of a pair of a movable electrode and a fixed electrode and a drive unit made of a member that is driven to vibrate by a drive signal are formed on the same substrate, and the movable electrode of the capacitor unit is formed by the drive unit. A variable capacitor capable of changing the capacitance of the capacitor unit by being driven to vibrate,
The driving unit and the movable electrode of the capacitor unit are formed as separate bodies separated from each other, and are arranged on the substrate so as to be separated from each other, and between the driving unit and the movable electrode of the capacitor unit A variable capacitor, wherein the capacitors are connected to each other via a support beam having an electrically insulating structure for insulation. The variable capacitor according to claim 1,
The variable capacitor according to claim 1, wherein the movable electrode of the capacitor unit and the driving unit are formed as members having different natural frequencies. The variable capacitor according to claim 2, wherein
The movable electrode of the capacitor unit and the drive unit are configured to have different natural frequencies by forming at least one of a cross-sectional shape, a length or a width, and a material different from each other. Characteristic variable capacitor. The variable capacitor according to any one of claims 1 to 3,
The support capacitor is fixed to the substrate with a space between the substrate and the substrate. A capacitor unit composed of a pair of a movable electrode and a fixed electrode and a drive unit made of a member that is driven to vibrate by a drive signal are formed on the same substrate, and the movable electrode of the capacitor unit is formed by the drive unit. A variable capacitor capable of changing the capacitance of the capacitor unit by being driven to vibrate,
The drive unit and the movable electrode of the capacitor are formed as separate bodies separated from each other, and are disposed on the substrate so as to be separated from each other, and between the drive unit and the movable electrode of the capacitor, A variable capacitor, characterized in that an electrically insulating fluid for transmitting vibration of the drive unit is interposed. The variable capacitor according to claim 5,
The variable capacitor, wherein the electrically insulating fluid is a gas. The variable capacitor according to claim 5,
The variable capacitor, wherein the electrically insulating fluid is a liquid. The variable capacitor according to any one of claims 5 to 7,
The variable capacitor according to claim 1, wherein the movable electrode of the capacitor unit and the driving unit are formed as members having different natural frequencies. The variable capacitor according to claim 8, wherein
The movable electrode of the capacitor unit and the driving unit are configured to have different natural frequencies by forming at least one of a cross-sectional shape, a length or width, a height, or a material different from each other. A variable capacitor characterized by