JPWO2013168191A1 - Electrostatic actuators and variable capacitance devices - Google Patents

Abstract

The electrostatic force at the time of separation can be generated effectively, and a high separation force can be obtained with a simple configuration. A fixed drive electrode 21 fixed to the silicon substrate 2 and a movable drive electrode 22 that faces the fixed drive electrode 21 on the lower surface and is close to the fixed drive electrode 21 due to electrostatic force between the fixed drive electrode 21 and the silicon substrate 2. And a separation electrode 24 that faces the upper surface of the movable drive electrode 22 and separates the movable drive electrode 22 from the fixed drive electrode 21 by electrostatic force between the movable drive electrode 22 and the separation electrode 24. The movable drive electrode 22 is partially fixed, and the movable drive electrode 22 and the separation electrode 24 are deformed so that the movable drive electrode 22 and the separation electrode 24 are expanded so that the fixed portion is centered. The drive electrode 22 receives the detachable movement with respect to the fixed drive electrode 21.

Description

  The present invention relates to an electrostatic actuator and a variable capacitance device that have a fixed electrode and a movable electrode facing the fixed electrode, and make use of electrostatic force to separate the movable electrode from the fixed electrode.

  Conventionally, as a variable capacitor (variable capacitor device), a variable capacitor having a signal line and an electrode facing the variable capacitor and a pair of actuators having a bridge structure connected to both sides of the variable capacitor are known. (See Patent Document 1). Each actuator unit has a movable upper electrode, a fixed lower electrode facing the movable upper electrode, and a spring structure connected to the upper electrode. Then, by applying a voltage between the upper electrode and the lower electrode, a potential difference is given between the upper electrode and the lower electrode. As a result, an electrostatic force is generated between the upper electrode and the lower electrode, and the upper electrode and the lower electrode are brought close to each other.

JP 2008-278634 A

By the way, with this type of variable capacitor, a high pulling force is required when the upper electrode is pulled away from the lower electrode by hot switching (driving method in which the actuator is driven with voltage applied to the variable capacitor). It may be. In the above-described conventional configuration, the movable electrode is pulled apart by the restoring force of the spring structure, so it is conceivable to increase the spring constant of the spring structure, but this requires high static electricity to bring the movable electrode close to each other. Since force is required, there has been a problem that a high voltage must be applied in the vicinity or the facing area of both electrodes must be increased.
On the other hand, a configuration was considered in which a third electrode was simply added above the upper electrode, and an electrostatic force was generated between the upper electrode and the third electrode to separate the movable electrode. However, this configuration requires a third electrode support member in addition to the upper electrode support member (beam or anchor), and there is a problem that electrostatic force is not effectively generated at the start of the separation operation. is assumed. That is, the electrostatic force is inversely proportional to the square of the separation distance between the upper electrode and the third electrode, whereas at the start of the separation operation, the upper electrode is close to the lower electrode, and the upper electrode is the third electrode. It is in a state far from the maximum. Therefore, no strong electrostatic force is generated at the start of the separation operation. As a result, the initial movement is slow, and the operation speed of the entire separation operation is slow, so that the electrostatic actuator cannot be stably operated.

  It is an object of the present invention to provide an electrostatic actuator and a variable capacitance device that can effectively generate an electrostatic force at the time of separation and can obtain a high separation force with a simple configuration.

  The electrostatic actuator of the present invention includes a fixed electrode fixed to the substrate, a movable electrode that faces the fixed electrode on one side of the front and back, and that is close to the fixed electrode by electrostatic force between the fixed electrode and the fixed electrode. A separation electrode that faces the other surface of the movable electrode and separates the movable electrode from the fixed electrode by electrostatic force between the movable electrode, and the separation electrode partially fixes the movable electrode. The movable electrode and the pulling electrode are deformed so that the movable electrode and / or the pulling electrode are spread around the fixed portion of each other, and the movable electrode and the pulling electrode receive the movable movement of the movable electrode with respect to the fixed electrode. And

  According to this configuration, first, since the separation electrode partially fixes the movable electrode, if the support member that supports the separation electrode is provided, it is necessary to provide a special support member for the movable electrode. There is no. Secondly, in order to deform so as to expand around the fixed part and accept the movable movement of the movable electrode, in the vicinity of the fixed part, the movable electrode and the separation electrode are always in close proximity, High electrostatic force can be generated. As a result, the electrostatic force at the time of separation can be effectively generated even at the start of the separation operation, and a high separation force can be obtained with a simple configuration. Therefore, since the initial movement is fast and the operation speed of the entire separation operation is increased, the operation of the electrostatic actuator can be performed stably. In this configuration, the movable electrode and the separation electrode are configured to be non-conductive.

  In this case, it is preferable that the movable electrode and / or the separation electrode are deformed with elasticity, and the restoring force of the deformation acts as the separation force of the movable electrode.

  According to this configuration, since the movable electrode is separated by the restoring force of elastic deformation and the electrostatic force by the separation electrode, a higher separation force can be obtained.

  In addition, the fixed electrode is connected to a first applied power source that applies a predetermined pull-in operating voltage for generating an electrostatic force at the time of proximity, the movable electrode is connected to a reference potential point, and the separation electrode is connected to the pulling electrode. It is preferable to be connected to a second applied power source that applies a predetermined pull-out operating voltage for generating an electrostatic force at the time of separation.

If there is a potential difference between the movable electrode and the separation electrode at the time of proximity, the electrostatic force hinders the proximity operation. Further, if a potential difference is generated between the fixed electrode and the movable electrode at the time of separation, the electrostatic force interferes with the separation operation (separation). Therefore, the movable electrode and the separation electrode need to have the same potential when approaching, and the fixed electrode and the movable electrode need to have the same potential when separated. Therefore, for example, when the pull-out operation voltage is applied to the movable electrode and the movable electrode is separated, it is necessary to apply the pull-out operation voltage and the GND voltage (reference voltage) to the fixed electrode and the separation electrode accordingly. The potential control becomes complicated.
On the other hand, according to the above configuration, the pull-in operating voltage is applied to the movable electrode by applying the pull-in operating voltage to the fixed electrode, applying the pull-out operating voltage to the separating electrode, and connecting and disconnecting the movable electrode. The potential control can be performed with a simple configuration. Note that the “predetermined pull-in operating voltage” is a voltage equal to or higher than a voltage (so-called pull-in voltage) at which the movable electrode is moved close to (pulled in) by electrostatic force. Further, the “predetermined pull-out operating voltage” is a voltage equal to or higher than a voltage (so-called pull-out voltage) at which the movable electrode is moved away (pulled out) by electrostatic force.

  Furthermore, n (n ≧ 1) additional separating electrodes connected in the direction of separating the movable electrode from the separating electrode are further provided, and the connected separating electrode and the n additional separating electrodes are connected. The front and back electrodes face each other, and the electrostatic force between them acts as a pulling force of the movable electrode via the pulling electrode, and is deformed into a bellows shape together with the moving electrode, so that the fixed electrode of the movable electrode It is preferable to accept the detachment movement relative to.

  According to this configuration, a higher pulling force can be obtained by providing n additional pulling electrodes. Further, since n additional separating electrodes are connected to the separating electrode, if a support member for supporting the outermost additional separating electrode is provided, (n-1) additional separating electrodes, There is no need to provide a special support member for the separation electrode and the movable electrode. Furthermore, since the connected separating electrode and the n additional separating electrodes are deformed into a bellows shape (bellows shape), they are configured to be deformed so as to expand around the coupling portion. Therefore, as in the case of the movable electrode and the separation electrode, the front and rear electrodes are always close to each other in the vicinity of the connecting portion, and a high electrostatic force can be generated.

  In this case, the connected separation electrode and the n additional separation electrodes are deformed with elasticity, and the restoring force of the deformation acts as the separation force of the movable electrode. The electrostatic actuator described in 1.

  According to this configuration, since the restoring force due to the elastic deformation of the connected separating electrode and n additional separating electrodes is caused to act as the separating force, a higher separating force can be obtained.

  A variable capacitance device according to the present invention includes the electrostatic actuator described above and a variable capacitance element that varies the capacitance that is driven using the electrostatic actuator as a drive source.

  According to this configuration, it is possible to provide a highly stable variable capacitance device by using an electrostatic actuator that can stably operate. The “variable capacitance device” here includes a variable capacitance capacitor, a variable capacitance type switch, and the like.

  In this case, it is preferable that the electrostatic actuator perform the moving / separating operation of the movable electrode in a state where a voltage is applied to the variable capacitance element.

When so-called hot switching is performed in which the movable electrode is separated and connected while a voltage is applied to the variable capacitance element, an electrostatic force is generated between the pair of electrodes constituting the variable capacitance element, thereby preventing the movable electrode from being separated.
On the other hand, according to the said structure, hot switching can be performed stably by using the electrostatic actuator which can obtain a high pulling force.

  The variable capacitance element is connected in series and is connected in series to each of the two variable capacitance portions having variable capacitance and the upstream and downstream sides of the two variable capacitance portions, and the capacitance is fixed. Each of the variable capacitance portions is fixedly provided on the substrate, faces the fixed capacitance electrode, is displaced integrally with the movable electrode, and is displaced relative to the fixed capacitance electrode. It is preferable to have a movable capacitance electrode that is in contact with and away from the substrate.

  According to this configuration, the RF voltage is divided when hot switching of the RF voltage (Radio Frequency Voltage) is performed by connecting two variable capacitor units and two fixed capacitor units in series. The Thereby, the electrostatic force that prevents the movable electrode from being separated, that is, the electrostatic force between the fixed capacitor electrode and the movable capacitor electrode can be reduced as a whole. Further, the fixed capacitor electrode and the movable capacitor electrode can be in a floating state.

  The driving method of the electrostatic actuator of the present invention is such that the fixed electrode fixedly provided on the substrate faces the fixed electrode on one side of the front and back, and approaches the fixed electrode by electrostatic force between the fixed electrode and the fixed electrode. A movable electrode, and a separation electrode that faces the other surface of the movable electrode and separates the movable electrode from the fixed electrode by electrostatic force between the movable electrode and the separation electrode. The movable electrode and / or the separation electrode are deformed so that the movable electrode and the separation electrode expand about the mutual fixed portion, and the movable electrode and the separation electrode receive the movable movement of the movable electrode with respect to the stationary electrode. A driving method of an electrostatic actuator, in which a predetermined pull-in operating voltage for generating an electrostatic force in proximity is applied to a fixed electrode, a reference potential point is connected to a movable electrode, and a pulling electrode is connected to a pulling electrode. Static electricity when released And applying a predetermined pull-out operation voltage for generating.

  According to this configuration, first, since the separation electrode partially fixes the movable electrode, if the support member that supports the separation electrode is provided, it is necessary to provide a special support member for the movable electrode. There is no. Secondly, in order to deform so as to expand around the fixed part and accept the movable movement of the movable electrode, in the vicinity of the fixed part, the movable electrode and the separation electrode are always in close proximity, High electrostatic force can be generated. As a result, the electrostatic force at the time of separation can be effectively generated even at the start of the separation operation, and a high separation force can be obtained with a simple configuration. Therefore, since the initial movement is fast and the operation speed of the entire separation operation is increased, the operation of the electrostatic actuator can be performed stably. Furthermore, by applying a pull-in operating voltage to the fixed electrode, applying a pull-out operating voltage to the release electrode, and connecting and disconnecting the movable electrode, there is no need to apply a pull-in operating voltage or a pull-out operating voltage to the movable electrode. Control can be performed with a simple configuration.

  The electrostatic actuator of the present invention includes a planar fixed electrode fixedly provided on a substrate, a planar movable electrode facing the fixed electrode on one surface and the other surface, and facing the other surface of the movable electrode. A planar facing electrode, and an electrode support portion that is erected on the substrate and supports the facing electrode. The facing electrode partially fixes the movable electrode, and the movable electrode and the facing electrode are mutually It is characterized in that it can be expanded and deformed around the fixed part.

  According to this configuration, first, since the separation electrode partially fixes the movable electrode, it is not necessary to provide a special support member for the movable electrode. Secondly, in order to deform so as to expand around the fixed part and accept the movable movement of the movable electrode, in the vicinity of the fixed part, the movable electrode and the separation electrode are always in close proximity, High electrostatic force can be generated. As a result, the electrostatic force at the time of separation can be effectively generated even at the start of the separation operation, and a high separation force can be obtained with a simple configuration. Therefore, since the initial movement is fast and the operation speed of the entire separation operation is increased, the operation of the electrostatic actuator can be performed stably.

It is sectional drawing of the variable capacitor which concerns on embodiment. It is a top view of a variable capacitor. It is an exploded view of a variable capacitor. It is sectional drawing of an electrostatic actuator. It is explanatory drawing which showed the proximity | contact operation | movement and separation | spacing operation | movement of both the drive electrodes in an electrostatic actuator. It is sectional drawing which showed the 1st modification of the electrostatic actuator. It is sectional drawing of the variable capacitor which showed the modification of the variable capacitance element. (A) And (b) is the top view which showed the 2nd modification of the electrostatic actuator, (c) is the sectional view on the AA 'line of an electrostatic actuator.

  Hereinafter, an electrostatic actuator and a variable capacitance device according to an embodiment of the present invention will be described with reference to the accompanying drawings. In the present embodiment, a variable capacitor (variable capacitor device) using an electrostatic actuator is illustrated. The variable capacitor is a MEMS (Micro Electro Mechanical Systems) device, and is configured by forming an electronic circuit and a mechanical structure on a silicon substrate (semiconductor substrate) using a semiconductor integrated circuit manufacturing technique. The variable capacitor has a configuration in which a high separation force is obtained by a separation electrode that separates the movable drive electrode from the fixed drive electrode by electrostatic force and a movable structure of the movable drive electrode.

  As shown in FIGS. 1 and 2, the variable capacitor 1 includes a silicon substrate (substrate) 2, a variable capacitor 3 disposed on the silicon substrate 2, and a variable capacitor disposed on the silicon substrate 2. A pair of electrostatic actuators 4 connected to both sides of the element 3. That is, the variable capacitance capacitor 1 varies the capacitance of the variable capacitance element 3 using the pair of electrostatic actuators 4 as a drive source. An insulating layer 5 is formed on the surface of the silicon substrate 2, and the variable capacitance element 3 and a pair of electrostatic actuators 4 are disposed on the insulating layer 5. In the present embodiment, the direction in which the pair of electrostatic actuators 4 are connected to the variable capacitance element 3 is defined as the X-axis direction, and the direction orthogonal thereto is defined as the Y-axis direction. In addition, the thickness direction of the silicon substrate 2 is the vertical direction.

  The variable capacitance element 3 includes a fixed-side fixed capacitance electrode 11 laid on the silicon substrate 2 and a movable-side movable capacitance electrode 12 that faces the fixed capacitance electrode 11 from above. In addition, electrical contacts (input terminals) of the variable capacitive element 3 are arranged on the capacitive electrodes 11 and 12, respectively, and charges are accumulated on the capacitive electrodes 11 and 12 by voltage application. Reference numeral 14 denotes an extraction part of the movable capacitance electrode 12. Then, the electrostatic capacitance of the variable capacitance element 3 is varied in two stages by moving the movable capacitance electrode 12 close to and away from the fixed capacitance electrode 11 by the electrostatic actuator 4. Further, the fixed capacitor electrode 11 is covered with an insulating film 13, and the fixed capacitor electrode 11 and the movable capacitor electrode 12 are in contact with each other through the insulating film 13 in the proximity of both the capacitor electrodes 11 and 12. . In the present embodiment, the fixed capacitor electrode 11 and the movable capacitor electrode 12 are in contact with each other via the insulating film 13 in the proximity state of both the capacitance electrodes 11 and 12, but in the proximity state, the air gap The fixed capacitor electrode 11 and the movable capacitor electrode 12 may be configured to face each other through the gap.

  As shown in FIGS. 2 to 4, each electrostatic actuator 4 includes a fixed-side fixed drive electrode (fixed electrode) 21 laid on the silicon substrate 2 and a movable-side movable facing the fixed drive electrode 21 from above. A drive electrode (movable electrode) 22, a separation electrode (facing electrode) 24 that faces the movable drive electrode 22 from above and is connected to the movable drive electrode 22 via an insulator connecting portion 23, and the silicon substrate 2. And an electrode support portion 25 that supports the movable drive electrode 22 and the separation electrode 24 that are erected and connected to each other. In each electrostatic actuator 4, the movable drive electrode 22 and the separation electrode 24 that are connected to each other are deformed so as to expand, so that the movable drive electrode 22 is in contact with the fixed drive electrode 21.

  The fixed drive electrode 21 is a flat electrode, is laid on the silicon substrate 2, and faces the movable drive electrode 22 (flat portion 31 described later). The fixed drive electrode 21 is connected to a first applied power source W1 that applies a predetermined pull-in operation voltage (predetermined drive voltage). The fixed drive electrode 21 is connected to the movable drive electrode 22 by application of the predetermined pull-in operation voltage. Generates electrostatic force (electrostatic attractive force). The fixed drive electrode 21 brings the movable drive electrode 22 close by this electrostatic force. The fixed drive electrode 21 is covered with an insulating film 26, and the fixed drive electrode 21 and the movable drive electrode 22 are in contact with each other through the insulating film 26 in the proximity of the drive electrodes 21 and 22. . Note that the predetermined pull-in operation voltage is a voltage equal to or higher than a voltage (so-called pull-in voltage) at which the movable drive electrode 22 is caused to approach (pull-in) by electrostatic force.

  The movable drive electrode 22 is a planar electrode, and faces the fixed drive electrode 21 on one surface (lower surface) of the front and back, and faces the separation electrode 24 on the other surface (upper surface). Further, the movable drive electrode 22 has one end portion in the X-axis direction (the opposite side to the variable capacitance element 3 side) fixed to the separation electrode 24 via the connecting portion 23, while the other end portion in the X-axis direction (variable) On the capacitive element 3 side), the movable capacitive electrode 12 is joined via an insulating joint 27 (see FIG. 1). That is, the movable capacitive electrode 12 is joined to the pair of movable drive electrodes 22 of the pair of electrostatic actuators 4 on both sides in the X-axis direction. As a result, the movable capacitive electrode 12 is displaced integrally with the pair of movable drive electrodes 22. The movable drive electrode 22 is connected to a ground (reference potential point) G and always has a reference potential (zero potential). Reference numeral 34 denotes an extraction portion of the movable drive electrode 22.

  The movable drive electrode 22 includes a flat portion 31 facing the fixed drive electrode 21 and a beam portion 32 (deformation) whose base end portion is separated and fixed to the electrode 24 and supports the flat portion 31 with a predetermined elasticity. Part) to form an integral electrode. That is, the beam portion 32 is elastically deformed so as to rotate around a portion fixed to the separation electrode 24 and moves the flat portion 31 up and down. Although not shown, strictly speaking, the flat portion 31 itself is also partially deformed by elasticity.

  The separation electrode 24 is a planar electrode, and partially fixes the movable drive electrode 22 at one end portion in the X-axis direction (the opposite side to the variable capacitance element 3 side), and the other end portion in the X-axis direction (variable capacitance element). 3 side) and is supported by the electrode support portion 25. Strictly speaking, the separation electrode 24 has a pair of left and right supported portions 24 a formed at the other end in the X-axis direction, and the pair of supported portions 24 a is supported by the electrode support portion 25. The separating electrode 24 is formed with a predetermined elasticity, and is elastically deformed so as to rotate around an end portion supported by the electrode support portion 25. As a result, the movable drive electrode 22 and the separation electrode 24 connected to each other are deformed so as to expand around the mutual fixed portion (in a horizontal “V” shape). Accordingly, the movable drive electrode 22 and the separation electrode 24 receive the vertical movement of the flat portion 31 and receive the movable movement of the movable drive electrode 22 with respect to the fixed drive electrode 21.

  Further, the separation electrode 24 faces the entire movable drive electrode 22 including the beam portion 32. The separation electrode 24 is connected to a second applied power source W2 that applies a predetermined pull-out operating voltage (predetermined driving voltage: DC voltage), and the movable driving electrode is applied by applying the predetermined pull-out operating voltage. An electrostatic force (electrostatic attraction force) is generated between the two. The separation electrode 24 separates the movable drive electrode 22 from the fixed drive electrode 21 and fixes the movable drive electrode 22 by the electrostatic force of the electrodes 22 and 24 in addition to the restoring force in the elastic deformation of the electrodes 22 and 24. Separated from the drive electrode 21. Note that the predetermined pull-out operating voltage is a voltage equal to or higher than a voltage (so-called pull-out voltage) at which the movable drive electrode 22 is moved away (pulled out) by electrostatic force.

  In the example of FIGS. 1 to 3, the pair of separation electrodes 24 of the pair of electrostatic actuators 4 are connected by the left and right supported portions 24a and are integrally formed so as to be conductive. Therefore, the pair of separating electrodes 24 do not need to be individually connected to the second applied power source W2, and if one separating electrode 24 is connected to the second applied power source W2, The other conducting separation electrode 24 is also connected to the second applied voltage W.

  The electrode support portion 25 has a pair of left and right first anchor portions 46 and second anchor portions 47 that support a pair of supported portions 24 a of the separation electrode 24. Further, the two first anchor portions 46 of the pair of electrostatic actuators 4 are integrally formed, and the two second anchor portions 47 of the pair of electrostatic actuators 4 are the extraction portions of the movable capacitive electrode 12. 14 are formed separately so as to avoid 14.

  Here, with reference to FIG. 5, the proximity | contact operation | movement of both the drive electrodes 21 and 22 and the separation | spacing operation | movement in the electrostatic actuator 4 are demonstrated. The proximity operation and the separation operation are performed in a state where an RF voltage is applied to the variable capacitance element 3 (so-called hot switching). Further, the proximity operation starts from a steady state in which both drive electrodes 21 and 22 are separated from each other, and the separation operation starts from a pull-in state in which both drive electrodes 21 and 22 are in proximity. As shown in FIG. 5 (a), in the steady state (the separated state of the drive electrodes 21 and 22), the pull-in operation voltage and the pull-out operation voltage are not applied, and the fixed drive electrode 21, the movable drive electrode 22 and the pulling operation voltage are not applied. The release electrodes 24 have the same potential (reference potential).

  As shown in FIG. 5B, in the proximity operation, the electrostatic actuator 4 controls the first application power source W1 to apply a predetermined pull-in operation voltage to the fixed drive electrode 21. When a pull-in operation voltage is applied, positive and negative charges are accumulated in the fixed drive electrode 21 and the movable drive electrode 22, and an electrostatic force is generated between the drive electrodes 21 and 22 due to the voltage difference. Due to the electrostatic force generated here, the movable drive electrode 22 and the separation electrode 24 are deformed so as to open against their restoring force. That is, the movable drive electrode 22 and the separation electrode 24 are deformed so that the portion supported by the electrode support portion 25 is fixed and the fixed portion between the electrodes 22 and 24 (around the connecting portion 23) is expanded. To do. Due to the deformation, the flat portion 31 of the movable drive electrode 22 is lowered, and the flat portion 31 is moved from the separated position to the close position with respect to the fixed drive electrode 21. That is, the movable drive electrode 22 is close to the fixed drive electrode 21. Thereby, the electrostatic actuator 4 shifts from the steady state to the pull-in state.

  As shown in FIG. 5C, in the pull-in state (the proximity of both drive electrodes 21 and 22), the flat portion 31 of the movable drive electrode 22 contacts the fixed drive electrode 21 through the insulating film 26. At this time, the movable drive electrode 22 and the separation electrode 24 have the same potential (reference potential), and the fixed drive electrode 21 continues to be applied with a predetermined pull-in operating voltage. Has a potential of. Note that the pull-in maintaining voltage necessary for maintaining the pull-in state is lower than the pull-in voltage necessary for moving the flat portion 31 in proximity. For this reason, in the pull-in state, a predetermined voltage lower than the pull-in operating voltage (however, a voltage equal to or higher than the pull-in maintaining voltage) may be applied.

  As shown in FIG. 5D, in the separation operation, the electrostatic actuator 4 controls the first applied power source W1 to stop the application of the pull-in operation voltage, and controls the second applied power source W2. A pull-out operating voltage is applied to the separation electrode 24. When the application of the pull-in operating voltage is stopped, the drive electrodes 21 and 22 are at the same potential, and the electrostatic force between the drive electrodes 21 and 22 is released. On the other hand, when a pull-out operating voltage is applied, positive and negative charges are accumulated in the movable drive electrode 22 and the separation electrode 24, and an electrostatic force is generated between the electrodes 22 and 24 due to the voltage difference. In particular, the vicinity of the mutual fixed portion is in a close state even at the start of the separation operation, so that a strong electrostatic force is generated. As a result, the movable drive electrode 22 and the separation electrode 24 are deformed so as to be closed by the restoring force of the movable drive electrode 22 (beam portion 32) and the separation electrode 24 and the electrostatic force between the electrodes 22 and 24. Go. By this deformation, the flat portion 31 of the movable drive electrode 22 is raised, and the flat portion 31 is separated from the fixed drive electrode 21. Then, the flat part 31 moves from the proximity position to the separation position. That is, the movable drive electrode 22 is separated from the fixed drive electrode 21. Thereafter, the application of the pull-out operating voltage is stopped. Thereby, the electrostatic actuator 4 shifts from the pull-in state to the steady state.

  Next, a modified example of the electrostatic actuator 4 will be described with reference to FIG. As shown in FIG. 6, in addition to the electrodes shown in FIG. 1, the electrostatic actuator 4 according to the modification includes an additional separating electrode that is connected to the separating electrode 24 from above while facing the separating electrode 24 from above. 51 is provided. The additional separating electrode 51 is supported by the electrode support portion 25 at the supported portion 51a at one end portion in the X axis direction (variable capacitance element 3 side), and at the other end portion in the X axis direction (the opposite side to the variable capacitance element 3 side). It is connected to the separation electrode 24 through a connecting portion 52 of an insulator. Further, the additional separating electrode 51 is formed with a predetermined elasticity like the separating electrode 24. The connected separation electrode 24 and the additional separation electrode 51 are elastically deformed into a bellows shape (bellows shape) together with the movable drive electrode 22 to receive the movable movement of the movable drive electrode 22. . Furthermore, the additional separation electrode 51 is connected to the ground G.

  When the pull-out operation voltage is applied to the separation electrode 24 during the separation operation of the drive electrodes 21 and 22, charges different in positive and negative are accumulated between the separation electrode 24 and the additional separation electrode 51. Power is generated. This electrostatic force and the elastic deformation restoring force of the additional separation electrode 51 act as the separation force of the movable drive electrode 22 and contribute to the separation of the movable drive electrode 22.

  According to this modification, by providing the additional separation electrode 51, a higher separation force can be obtained. Further, since the additional separation electrode 51 is connected to the separation electrode 24, the movable drive electrode 22 and the separation electrode 24 can be provided by providing a support member (electrode support portion 25) that supports the additional separation electrode 51. There is no need to provide a special support member. Furthermore, since the connected separation electrode 24 and the additional separation electrode 51 are deformed into a bellows shape (bellows shape), the structure is deformed so as to expand around the connection portion. Therefore, as in the case between the movable drive electrode 22 and the separation electrode 24, the front and rear electrodes are always close to each other in the vicinity of the connection portion, and a high electrostatic force can be generated. Furthermore, a higher separating force can be obtained by applying the restoring force due to the elastic deformation of the additional separating electrode 51 as the separating force.

  In the present modification, one additional separation electrode 51 is connected upward from the separation electrode 24. However, n (n ≧ 1) additional separation electrodes 51 may be connected. For example, the structure which connects the some additional separation electrode 51 may be sufficient. That is, the first additional separation electrode 51 is fixed to the separation electrode 24 at the end while facing the separation electrode 24 from above, and the additional separation electrode 51 thereafter is connected to the previous one. The additional separating electrode 51 is fixed at the end while facing the additional separating electrode 51. That is, the connected separation electrode 24 and the n additional separation electrodes 51 are configured such that the electrodes before and after the connection face each other. Then, an electrostatic force is generated between the front and rear electrodes, and the electrostatic force is separated to act as a separation force of the movable drive electrode 22 via the electrode 24. In this case, the odd-numbered additional pull-out electrodes 51 are connected to the ground G and the even-numbered additional pull-out electrodes 51 have a pull-out operating voltage in order of connection so that a potential difference occurs between the front and rear electrodes. A pull-out operation voltage is applied to the second application power source W2 to be applied and during the separation operation. Moreover, in this structure, it is preferable that a connection part is alternately located by the X-axis direction one end part and other end part.

  Next, a modification of the variable capacitance element 3 will be described with reference to FIG. In this modification, an insulating substrate 6 is used instead of the silicon substrate 2. As shown in FIG. 7, the variable capacitor 3 according to the modification includes a pair of fixed capacitance electrodes 11 laid on an insulating substrate 6, a movable capacitance electrode 12 facing the pair of fixed capacitance electrodes 11 from above, and insulation. And a pair of embedded capacitor electrodes 60 which are embedded in the conductive substrate 6 and face each other through the insulating layer 5 on the lower surfaces of the pair of fixed capacitor electrodes 11. The pair of fixed capacitance electrodes 11 and the movable capacitance electrode 12 constitute two variable capacitance portions 61 whose capacitance is variable, and the pair of fixed capacitance electrodes 11 and the pair of embedded capacitance electrodes 60 are electrostatic capacitances. Two fixed capacity portions 62 having a fixed capacity are configured (see FIG. 7C). The pair of embedded capacitor electrodes 60 are provided with electrical contacts (input terminals) of the variable capacitor 3, respectively. The pair of fixed capacitor electrode 11, the movable capacitor electrode 12, and the pair of embedded capacitor electrodes 60 are From the upstream side, one fixed capacitor 62, two variable capacitors 61, and the other fixed capacitor 62 are configured in series in this order. The pair of fixed capacitor electrodes 11 and the pair of movable capacitor electrodes 12 are in a floating state.

  According to this modification, since the RF voltage at the time of hot switching is divided by connecting two variable capacitor portions 61 and two fixed capacitor portions 62 in series, the movable drive electrode 22 is separated. Can be reduced as a whole, that is, the electrostatic force between the fixed capacitor electrode 11 and the movable capacitor electrode 12 can be reduced. Further, the pair of fixed capacitor electrode 11 and movable capacitor electrode 12 can be in a floating state. In this modification, the insulating substrate 6 is used so that the pair of adjacent embedded capacitance electrodes 60 are not conductive. However, the silicon substrate 2 may be used instead of the insulating substrate 6. However, it is preferable to use the insulating substrate 6 because the PN junction of the silicon substrate 2 is not sufficient to ensure the insulation between the adjacent embedded capacitance electrodes 60.

  In this modification, the movable capacitance electrodes 12 of the two variable capacitance portions 61 are integrally formed. However, the movable capacitance electrodes 12 of the two variable capacitance portions 61 are formed separately. It may be a configuration.

  According to the above embodiment, first, since the separation electrode 24 partially fixes the movable drive electrode 22, a support member (electrode support portion 25) for supporting the separation electrode 24 can be provided. In this case, it is not necessary to provide a special support member for the movable drive electrode 22. Second, the movable drive electrode 22 and the separation electrode 24 are always close to each other in the vicinity of the fixed portion in order to deform so as to expand around the fixed portion and receive the movable movement of the movable drive electrode 22. Thus, a high electrostatic force can be generated. As a result, the electrostatic force at the time of separation can be effectively generated even at the start of the separation operation, and a high separation force can be obtained with a simple configuration. Therefore, since the initial movement is fast and the operation speed of the entire separation operation is increased, the operation of the electrostatic actuator 4 can be stably performed.

For example, when the electrostatic force F1 between the electrodes 22 and 24 when the pullout operation voltage V is applied at the start of the separation operation is calculated, the following is obtained. That is, the width of the movable drive electrode 22 is W, the distance from the fixed portion to the tip portion of the movable drive electrode 22 is L, the distance from the separation electrode 24 at the fixed portion is G0, and the separation electrode 24 at the tip portion. Let G1 be the separation distance. Then, when the separation distance f (x) from the fixed part to the tip part is calculated by linear approximation,
f (x) = (G1-G0) × x / L + G0
It becomes. Here, x is a position coordinate in which the fixed portion is zero.
When the electrostatic force F1 is calculated using this,
F1 = (1/2) × ε0 × W × L × V ² / (G0 × G1)
It becomes. On the other hand, in the configuration in which the separation electrode 24 is disposed above and in parallel with the movable drive electrode 22, the separation distance from the separation electrode 24 is G1 in the entire region, and the pull-out operation voltage V is applied. When the electrostatic force F0 between the two electrodes 22 and 24 is calculated,
F0 = (1/2) × ε0 × W × L × V ² / (G1) ²
It becomes. Considering that G1 is much higher than G0, it can be seen that the former electrostatic force F1 is much higher than the latter electrostatic force F0.

  Further, since the movable drive electrode 22 and the separation electrode 24 are deformed with elasticity, the movable drive electrode 22 is separated by the restoring force of the elastic deformation and the electrostatic force by the separation electrode 24, so that a higher pulling force is obtained. Release force can be obtained. If this is not taken into consideration, the movable drive electrode 22 and / or the separation electrode 24 may be deformed without having elasticity (spring property). That is, the movable drive electrode 22 may be separated only by electrostatic force.

  Further, a pull-in operation voltage is applied to the fixed drive electrode 21, a pull-out operation voltage is applied to the separation electrode 24, and the movable drive electrode 22 is separated and applied, thereby applying a pull-in operation voltage and a pull-out operation voltage to the movable drive electrode 22. This is unnecessary, and potential control can be performed with a simple configuration.

  In the present embodiment, the movable drive electrode 22 and the separation electrode 24 are both deformed to accept the movable movement of the movable drive electrode 22. Only one of them may be deformed to receive the movable movement of the movable drive electrode 22.

  In the present embodiment, the fixed drive electrode 21, the movable drive electrode 22, and the separation electrode 24 are arranged in parallel to the silicon substrate 2. However, the fixed drive electrode 21, the movable drive electrode 22, The separation electrode 24 may be arranged perpendicular to the silicon substrate 2 (see the plan views of FIGS. 8A and 8B and the cross-sectional view taken along the line AA ′ of FIG. 8C). ). In this case, the electrode support portion 25 is formed in a rectangular tube shape (a box shape having no upper and lower surfaces) that surrounds the fixed drive electrode 21, the movable drive electrode 22, and the separation electrode 24. The electrode support portion 25 is erected on the silicon substrate 2 via the insulating portion 71, and supports the one end portion in the X-axis direction of the separation electrode 24 and the fixed drive electrode 21 via the insulating portion 71.

  In the present embodiment, the present invention is applied to the variable capacitor 1 as the variable capacitance device. However, the present invention may be applied to a variable capacitance type switch using the variable capacitance element 3.

  In the present embodiment, the present invention is applied as a countermeasure against hot switching, that is, as a structure that stabilizes hot switching. However, hot switching is performed if a high separating force is required. It is not limited to cases. For example, as a countermeasure against sticking (stiction) between the drive electrodes 21 and 22, the present invention may be applied, and as a method of reducing the electrostatic force when approaching, a spring structure portion (beam portion 32 or the like). It is also possible to adopt a configuration in which the present invention is applied while lowering (or zeroing) the spring constant.

  1: variable capacitance capacitor, 2: silicon substrate, 3: variable capacitance element, 4: electrostatic actuator, 11: fixed capacitance electrode, 12: movable capacitance electrode, 21: fixed drive electrode, 22: movable drive electrode, 24: pull Release electrode, 25: Electrode support part, 51: Additional separation electrode, 61: Variable capacity part, 62: Fixed capacity part, G: Ground, W1: First applied power supply, W2: Second applied power supply

Claims (10)

A fixed electrode fixed to the substrate;
A movable electrode facing the fixed electrode on one side of the front and back, and an electrostatic force between the fixed electrode and the fixed electrode,
A separation electrode that faces the other surface of the movable electrode, and that separates the movable electrode from the fixed electrode by electrostatic force between the movable electrode, and
The separation electrode partially fixes the movable electrode,
The movable electrode and / or the separation electrode are deformed so that the movable electrode and / or the separation electrode are expanded so that the fixed portions of the movable electrode and the separation electrode are spread around each other. An electrostatic actuator characterized by receiving.   2. The electrostatic according to claim 1, wherein the movable electrode and / or the separation electrode is deformed with elasticity, and a restoring force of the deformation acts as a separation force of the movable electrode. Actuator. The fixed electrode is connected to a first applied power source that applies a predetermined pull-in operating voltage for generating an electrostatic force in proximity.
The movable electrode is connected to a reference potential point;
The electrostatic actuator according to claim 1, wherein the separation electrode is connected to a second applied power source that applies a predetermined pull-out operating voltage for generating an electrostatic force at the time of separation. N (n ≧ 1) additional separating electrodes connected in the direction of separating the movable electrode from the separating electrode,
The connected separating electrode and the n additional separating electrodes are such that the connected front and back electrodes face each other, and the electrostatic force between them is taken as the separating force of the movable electrode via the separating electrode. 2. The electrostatic actuator according to claim 1, wherein the electrostatic actuator is deformed into a bellows shape together with the movable electrode and receives the movable movement of the movable electrode with respect to the fixed electrode.   5. The connected separation electrode and the n additional separation electrodes are deformed with elasticity, and a restoring force of the deformation acts as a separation force of the movable electrode. The electrostatic actuator described in 1. An electrostatic actuator according to claim 1;
A variable capacitance device comprising: a variable capacitance element that varies a capacitance driven by using the electrostatic actuator as a drive source.   The variable capacitance device according to claim 6, wherein the electrostatic actuator performs a separation / contact operation of the movable electrode in a state where a voltage is applied to the variable capacitance element. The variable capacitance element is
Two variable capacitance units connected in series and having variable capacitance;
Two fixed capacitance portions connected in series to the upstream and downstream sides of the two variable capacitance portions, and having a fixed capacitance,
Each of the variable capacitance units is
A fixed capacitance electrode fixedly provided on the substrate;
The variable capacitance device according to claim 6, further comprising: a movable capacitance electrode that faces the fixed capacitance electrode, is displaced integrally with the movable electrode, and is separated from or in contact with the fixed capacitance electrode. A fixed electrode fixed to the substrate;
A movable electrode facing the fixed electrode on one side of the front and back, and an electrostatic force between the fixed electrode and the fixed electrode,
A separation electrode that faces the other surface of the movable electrode, and that separates the movable electrode from the fixed electrode by electrostatic force between the movable electrode, and
The separation electrode partially fixes the movable electrode,
The movable electrode and / or the separation electrode are deformed so that the movable electrode and / or the separation electrode are expanded so that the fixed portions of the movable electrode and the separation electrode are spread around each other. A driving method of an electrostatic actuator to receive,
Applying a predetermined pull-in operating voltage for generating an electrostatic force in proximity to the fixed electrode,
A reference potential point is connected to the movable electrode,
A driving method of an electrostatic actuator, wherein a predetermined pull-out operation voltage for generating an electrostatic force at the time of separation is applied to the separation electrode. A planar fixed electrode fixed to the substrate;
A planar movable electrode facing the fixed electrode on one side of the front and back,
A planar facing electrode facing the other surface of the movable electrode; and
An electrode support portion that is erected on the substrate and supports the facing electrode;
The facing electrode partially fixes the movable electrode,
The electrostatic actuator, wherein the movable electrode and the facing electrode are configured to be able to expand and deform around a fixed portion of each other.

Images