WO2014058004A1

WO2014058004A1 - Variable capacitance capacitor

Info

Publication number: WO2014058004A1
Application number: PCT/JP2013/077562
Authority: WO
Inventors: 尚信大川; 村田　眞司; 矢澤　久幸; 亨宮武
Original assignee: アルプス電気株式会社
Priority date: 2012-10-11
Filing date: 2013-10-10
Publication date: 2014-04-17
Also published as: JPWO2014058004A1; JP5922249B2

Abstract

[Problem] The purpose of the present invention is to provide a variable capacitance capacitor configured so that a range of a variable capacitance can be increased and capacitance fluctuations due to influences of acceleration exerted from outside can be suppressed. [Solution] In this variable capacitance capacitor, a movable capacitor electrode part (30) and a movable driving electrode part (31) are linked by linking parts (51) and (52) at which a fulcrum part (61c) is provided; the linking parts (51) and (52) are provided rotatably around the fulcrum part (61c) as a fulcrum; the fulcrum part (61c) is provided so that a rotation radius of the linking parts (51) and (52) linked to the movable capacitor electrode part (30) around the fulcrum part (61c) as a fulcrum is greater than a rotation radius of the linking parts (51) and (52) linked to the movable driving electrode part (31); and the movable capacitor electrode part (30) and the movable driving electrode part (31)are formed so that the mass per unit area of the movable capacitor electrode part (30) is smaller than that of the movable driving electrode part (31).

Description

Variable capacitor

The present invention relates to a variable capacitor, and more particularly to a variable capacitor having a large variable capacitance range.

In portable devices such as mobile phones, it is expected to reduce the number of components and reduce the size of the device by using variable capacitors in the oscillation circuit and control circuit.

Such a variable capacitor can be mass-produced by a micro device technology called MEMS (Micro Electro Mechanical Systems). MEMS is suitable for downsizing and can be made relatively inexpensive if mass-produced. Therefore, it is expected to contribute to downsizing and high performance of portable devices. Furthermore, since the frequency band used for mobile phones is a wide band such as 700 MHz to 2.5 GHz, a variable capacitor having a variable ratio of about 10 times the maximum capacitance to the minimum capacitance is desired. Has been.

FIG. 9 is a perspective view of the variable capacitor 110 of the first conventional example described in Patent Document 1. FIG. As shown in FIG. 9, in the variable capacitor 110 of the first conventional example, the fixed portion 120 and the movable portion 130 are arranged to face each other with a space therebetween. A beam 150 is provided at the center of the movable portion 130 in the X1-X2 direction, and the movable portion 130 and the fixed portion 120 are fixed by the beam 150. The movable part 130 can be rotated by twisting of the beam 150. The fixed portion 120 is provided with a drive electrode 121 and a capacitive electrode 122 as fixed electrodes so as to face the movable portion 130. On the back surface of the movable portion 130, a movable electrode 131 is formed as a common electrode facing the drive electrode 121 and the capacitor electrode 122.

When a drive voltage is applied between the drive electrode 121 and the movable electrode 131, a potential difference is generated between the drive electrode 121 and the movable electrode 131, and an electrostatic force (cron force) is generated. Due to this electrostatic force, the movable part 130 is attracted to the drive electrode 121 with the beam 150 as the rotation axis. As a result, the distance between the capacitive electrode 122 and the movable electrode 131 changes in the increasing direction, so that the capacitance formed by the capacitive electrode 122 and the movable electrode 131 changes. The movable part 130 is displaced and stopped at a position where the Clone force and the restoring force against the torsion of the beam 150 are balanced. Therefore, the position where the movable portion 130 is displaced can be changed by the voltage value applied between the drive electrode 121 and the movable electrode 131, and can be adjusted to a desired capacitance value.

As a method of increasing the variable capacitance range of the variable capacitor 110 of the conventional example, there is a method of increasing the distance between the capacitive electrode 122 and the beam 150 with respect to the distance between the drive electrode 121 and the beam 150. FIG. 10 shows a schematic cross-sectional view of the variable capacitor 111 of the second conventional example when the variable range is enlarged. As shown in FIG. 10, in the movable part 130, the side on which the drive electrode 121 is provided is the movable drive electrode part 130a with the beam 150 as the rotation axis, and the side on which the capacitive electrode 122 is provided is the movable capacitive electrode part 130b. And The second conventional example variable capacitor 111 of the is provided with a length of the movable capacitor electrode portion 130b of the _{(L b)} to be longer than the length of the drive electrode portion 130a _{(L a).} Thereby, since the displacement amount of the capacitive electrode 122 and the movable electrode 131 can be increased with respect to the displacement amount of the drive electrode 121 and the movable electrode 131, the variable capacitance range can be further increased.

JP-A-9-153436

However, in the variable capacitor 111 of the second conventional example shown in FIG. 10, when acceleration is applied from the outside, the beam 150 is rotated around the axis of rotation according to the respective moments of inertia of the drive electrode portion 130 a and the capacitor electrode portion 130 b. As a result, a moment of force acts in the direction of rotating the drive electrode portion 130a and the capacitor electrode portion 130b. The magnitude of the moment of inertia of the drive electrode portion 130a and the capacitive electrode portion 130b is a value obtained by integrating the product of the square of the distance from the rotation axis and the mass per unit distance. Therefore, as shown in FIG. 10, the length _{L a} of the driving electrode portions 130a, mass and _{M a,} the length _{L b} of the capacitor electrode portion 130b, mass When _{M b,} the inertia of the driving electrode portions 130a The moment is expressed as (M _a × L _a ² ) / 3, and the moment of inertia of the capacitor electrode portion 130b is (M _b × L _b ² ) / 3. When the moments of inertia of the drive electrode portion 130a and the capacitive electrode portion 130b are equal, moments of equal forces in opposite directions work, so even when acceleration is applied from the outside, the drive electrode portion 130a and the capacitive electrode portion 130b does not rotate.

In the variable capacitor 111 of the conventional example, since the length L _b of the length L _a and the capacitance electrode part 130b of the driving electrode portions 130a are different, it shifted the balance of the magnitude of the moment of inertia. Therefore, when acceleration is applied from the outside, the moments of the forces acting in the rotational direction of the drive electrode portion 130a and the capacitive electrode portion 130b are different, and the distance between the capacitive electrode 122 and the capacitive electrode portion 130b varies. For this reason, the capacitance of the variable capacitor 111 varies, resulting in a value that deviates from the desired capacitance value.

An object of the present invention is to solve the above-described problems and to provide a variable capacitor capable of increasing the variable capacitance range and suppressing capacitance fluctuation due to the influence of externally applied acceleration.

The variable capacitance capacitor of the present invention includes a movable drive electrode portion and a fixed drive electrode portion arranged to face each other, and a movable capacitance electrode portion and a fixed capacitance electrode portion arranged to face each other, and the movable drive electrode In the variable capacitor formed so that the movable portion and the movable capacitive electrode portion are interlocked with a fulcrum portion as a fulcrum, the movable capacitive electrode portion and the movable drive electrode portion are formed by a link portion provided with the fulcrum portion. The link portion rotates with the fulcrum portion as a fulcrum so that the movable capacitance electrode portion is separated from the fixed capacitance electrode portion when the movable drive electrode portion is connected to the fixed drive electrode portion. The rotation radius of the link portion on the side connected to the movable capacitive electrode portion with the fulcrum portion serving as a fulcrum is set to the link portion on the side connected to the movable drive electrode portion. The fulcrum part is provided so as to be larger than the rotation radius, and the mass per unit area of the movable capacitive electrode part is smaller than the mass per unit area of the movable drive electrode part. The movable capacitor electrode part and the movable drive electrode part are formed.

According to this, since the rotation radius of the link portion connected to the movable capacitive electrode portion is larger than the rotation radius of the link portion connected to the movable drive electrode portion with the fulcrum portion as the fulcrum, the movable drive When the distance between the electrode portion and the fixed drive electrode portion is displaced, the displacement amount of the distance between the movable capacitance electrode portion and the fixed capacitance electrode portion can be further increased. Therefore, the variable capacitance range of the variable capacitor can be increased. Further, the rotation radius of the link portion connected to the movable capacitance electrode portion is larger than the rotation radius of the link portion connected to the movable drive electrode portion, and the movable capacitance electrode portion is larger than the movable drive electrode portion. The mass per unit area is small. As a result, the difference between the moment of inertia of the movable capacitive electrode portion and the moment of inertia of the movable drive electrode portion can be reduced, so that when acceleration is applied from the outside, the movable capacitive electrode portion and the movable drive electrode portion The difference in moment of working force can be reduced. Therefore, it is possible to suppress the displacement of the capacitance by suppressing the displacement of the movable capacitance electrode portion and the movable drive electrode portion due to the influence of the acceleration applied from the outside.

Therefore, according to the variable capacitor of the present invention, it is possible to increase the variable capacitance range and suppress capacitance fluctuation due to the influence of acceleration applied from the outside.

In the variable capacitor of the present invention, the product of the square of the rotational radius of the link portion on the side connected to the movable capacitance electrode portion and the mass of the movable capacitance electrode portion is connected to the movable drive electrode portion. It is preferable that it is formed to be equal to the product of the square of the radius of rotation of the link portion on the side and the mass of the movable drive electrode portion. According to this, since the moment of inertia of the movable capacitor electrode portion becomes equal to the moment of inertia of the movable drive electrode portion, it is possible to suppress the displacement of the movable capacitor electrode portion and the movable drive electrode portion due to the influence of externally applied acceleration. it can.

In the variable capacitor of the present invention, the movable capacitor electrode part and the movable drive electrode part are formed in a flat plate shape, and the thickness of the movable capacitor electrode part is formed thinner than the movable drive electrode part. Is preferred.

In the variable capacitor of the present invention, it is preferable that a hole is provided in the movable capacitor electrode portion.

In the variable capacitor of the present invention, it is preferable that a mass adjusting unit is provided in the movable drive electrode unit.

According to these aspects, by reducing the mass of the movable capacitive electrode part or increasing the mass of the movable drive electrode part, the difference in the moment of inertia between the movable capacitive electrode part and the movable drive electrode part is reduced, Capacitance fluctuation can be suppressed.

The variable capacitance capacitor of the present invention includes a movable drive electrode portion and a fixed drive electrode portion arranged to face each other, and a movable capacitance electrode portion and a fixed capacitance electrode portion arranged to face each other, and the movable drive electrode In the variable capacitance capacitor formed so that the movable portion and the movable capacitive electrode portion rotate in conjunction with the fulcrum portion as a fulcrum, the rotational radius of the movable capacitive electrode portion is larger than the rotational radius of the movable drive electrode portion. The movable capacitance electrode is provided such that the fulcrum portion is provided so that the mass per unit area of the movable capacitance electrode portion is smaller than the mass per unit area of the movable drive electrode portion. Part and the movable drive electrode part are formed.

According to this, since the rotational radius of the movable capacitive electrode portion is larger than the rotational radius of the movable drive electrode portion, the movable capacitive electrode portion is fixed to the movable capacitive electrode portion when the distance between the movable drive electrode portion and the fixed drive electrode portion is displaced. The displacement amount of the distance with the capacitive electrode part can be increased. Therefore, the variable capacitance range of the variable capacitor can be increased. Furthermore, the movable capacitance electrode part has a larger radius of rotation and a smaller mass per unit area than the movable drive electrode part. As a result, the difference between the moment of inertia of the movable capacitive electrode portion and the moment of inertia of the movable drive electrode portion can be reduced, so that when acceleration is applied from the outside, the movable capacitive electrode portion and the movable drive electrode portion The difference in moment of working force can be reduced. Therefore, it is possible to suppress the displacement of the capacitance by suppressing the displacement of the movable capacitance electrode portion and the movable drive electrode portion due to the influence of the acceleration applied from the outside.

According to the variable capacitor of the present invention, it is possible to increase the variable capacitance range and suppress capacitance fluctuation due to the influence of acceleration applied from the outside.

It is a disassembled perspective view of the variable capacitor in the 1st Embodiment of this invention. It is a top view of the variable capacitor of a 1st embodiment. FIG. 3 is a cross-sectional view taken along the line III-III in FIG. It is a schematic diagram for demonstrating the moment of inertia of the variable capacitor of 1st Embodiment. It is a top view of the variable capacitor in the 1st modification. It is sectional drawing of the variable capacitor in a 2nd modification. It is sectional drawing of the variable capacitor in a 3rd modification. It is sectional drawing of the variable capacitor in 2nd Embodiment. It is a perspective view which shows the variable capacitor of the 1st prior art example. It is sectional drawing of the variable capacitor of the 2nd prior art example.

Hereinafter, a variable capacitor according to an embodiment of the present invention will be described in detail with reference to the drawings. In addition, the dimension of each drawing is changed and shown suitably.

<First Embodiment>
FIG. 1 is an exploded perspective view of the variable capacitor 10 of the first embodiment. FIG. 2 is a plan view of the variable capacitor 10 of the first embodiment.

As shown in FIG. 1, the variable capacitor 10 of the present embodiment includes a fixed portion 20, a movable capacitance electrode portion 30, and a movable drive electrode portion 31. The fixed portion 20 includes a fixed capacitance electrode portion 20a and a fixed drive electrode portion 20b. The fixed drive electrode portion 20b is disposed to face the movable drive electrode portion 31, and the fixed capacitance electrode portion 20a is movable. The capacitor electrode part 30 is disposed opposite to the capacitor electrode part 30. In addition, the movable capacitor electrode part 30 and the movable drive electrode part 31 are connected by a first link part 51 and a second link part 52.

As shown in FIG. 2, the first link portion 51 is connected to the first connection portion 36 a provided in the movable drive electrode portion 31 and is provided at the X1 side end portion of the movable capacitance electrode portion 30. It is connected to the first connecting portions 36b and 36c. The second link portion 52 is provided point-symmetrically with the first link portion 51. As described above, the movable capacitance electrode unit 30 and the movable drive electrode unit 31 are connected by the first link unit 51 and the second link unit 52. Further, the first auxiliary link portion 53 and the second auxiliary link portion 54 for supporting the movable capacitive electrode portion 30 and the movable drive electrode portion 31 by assisting the first link portion 51 and the second link portion 52. Is provided. The first link 51 and the joints 65a and 65c are connected by fulcrum parts 61a and 61c, and the second link part 52 and the joints 65b and 65d are connected by fulcrum parts 61b and 61d. Has been.

As shown in FIG. 1, the joint support portions 26 a, 26 b, 26 c, and 26 d formed on the fixed portion 20 are joined to the joint portions 65 a, 65 b, 65 c, and 65 d, respectively. The drive electrode portion 31 and the fixed portion 20 are joined. The first link portion 51 and the second link portion 52 are provided so as to be rotatable with the fulcrum portions 61a to 61d as fulcrums. Therefore, the movable capacitor electrode part 30 and the movable drive electrode part 31 connected by the first link part 51 and the second link part 52 operate so as to rotate in conjunction with the fulcrum parts 61a to 61d as fulcrums. That is, when the movable drive electrode part 31 is displaced in the Z2 direction and approaches the fixed part 20, the movable capacitive electrode part 30 is displaced in the Z1 direction so as to be separated from the fixed part 20, or vice versa. A first link portion 51 and a second link portion 52 are provided. Note that the first auxiliary link portion 53 is connected to a fulcrum portion 63 a provided in the joint portion 65 a and can be interlocked with the first link portion 51. Similarly, the second auxiliary link portion 54 can be interlocked with the second link portion 52.

The movable capacitive electrode part 30, the movable drive electrode part 31, the first link part 51, the second link part 52, and the like are formed using a silicon substrate that is a rectangular flat plate. First, a resist layer corresponding to the shape of each member is formed on a silicon substrate. Then, the silicon substrate is cut by an etching process such as deep RIE (deep reactive ion etching) at a portion where the resist layer is not present, so that the movable capacitor electrode portion 30, the movable drive electrode portion 31 and the like are cut. Each member is formed.

The movable capacitor electrode portion 30 and the movable drive electrode portion 31 are very small. For example, the length of the movable drive electrode portion 31 in the X1-X2 direction is 1 mm or less, and the length in the Y1-Y2 direction is 0.8 mm or less. is there. Furthermore, the thickness dimension is 0.1 mm or less.

FIG. 3 is a cross-sectional view for explaining the operation of the movable capacitor electrode portion 30 and the movable drive electrode portion 31, and is a cross-sectional view taken along the line III-III in FIG. . FIG. 3A shows a state in which no drive voltage is applied between the movable drive electrode portion 31 and the fixed drive electrode portion 20b, and FIG. 3B shows a cross section in a state where the drive voltage is applied and displaced. FIG.

As shown in FIG. 3 (a), the variable capacitor 10 of this embodiment is configured to have a pair of capacitive electrodes and a pair of drive electrodes. As shown in FIG. 3A, the fixed capacitance electrode portion 20a is provided with a fixed capacitance electrode 24, and the movable capacitance electrode portion 30 is formed on the movable capacitance electrode portion 30 opposite to the fixed capacitance electrode portion 20a. Yes. A fixed drive electrode 25 is formed on the fixed drive electrode portion 20b, and a movable drive electrode 35 is formed on the movable drive electrode portion 31.

The movable capacitive electrode unit 30 and the movable drive electrode unit 31 are conductive materials, the material of the movable capacitive electrode unit 30 functions as the movable capacitive electrode 34, and the material of the movable drive electrode unit 31 is the movable drive electrode. 35 is functioning.

The variable capacitor 10 is connected to a control unit (not shown) for controlling the electric capacity, and the drive voltage for generating an electrostatic force between the fixed drive electrode 25 and the movable drive electrode 35 is controlled. Given by the department.

As shown in FIG. 3A, in a state where the drive voltage is not applied, the distance D1 ′ between the movable drive electrode 35 and the fixed drive electrode 25 is equal to the distance D2 ′ between the movable capacitance electrode 34 and the fixed capacitance electrode 24. The movable drive electrode portion 31 and the movable capacitive electrode portion 30 are stationary in a state that is substantially the same as the above.

When a drive voltage is applied to the fixed drive electrode 25 and the movable drive electrode 35 that are a pair of drive electrodes, as shown in FIG. 3B, the movable drive electrode portion 31 is displaced by ΔD1 in the Z2 direction due to electrostatic force. To do. Then, the movable capacitive electrode portion 30 connected by the first link portion 51 and the second link portion 52 rotates in conjunction with the movable drive electrode portion 31 with the fulcrum portions 61a to 61d as fulcrums. It is displaced by ΔD2 in the direction. At this time, the first connecting portions 36a to 36d, the second connecting portions 37a to 37d, and the fulcrum portions 61a to 61d are torsionally deformed. This torsional deformation is an elastic deformation, and each of the connecting portions and the fulcrum portions 61a to 61d has a restoring force for returning to the original with respect to the torsional deformation. The movable capacitive electrode 30 and the movable drive electrode 31 are stationary at a position where the electrostatic force and the restoring force are balanced, and the capacitance formed by the fixed capacitive electrode 24 and the movable capacitive electrode 34 at this time is a variable capacitive capacitor. The electric capacity is 10. As described above, the displacement of the movable capacitor electrode 30 and the movable drive electrode 31 is controlled by the balance between the electrostatic force and the restoring force generated by the drive voltage, and the electric capacity of the variable capacitor 10 is set to a desired value. Can do.

The displacement ΔD1 of the movable drive electrode portion 31 due to the drive voltage is limited to 1/3 of the interelectrode distance D1 ′ in the initial state due to a so-called pull-in effect. Therefore, the movable range of the movable capacitive electrode unit 30 connected to the movable drive electrode unit 31 by the first link unit 51 and the second link unit 52 is also limited. However, according to the variable capacitor 10 of the present embodiment, as shown in FIG. 2, the distance between the fulcrum portion 61a and the first connecting portion 36a and L _1, and the fulcrum portion 61a and the first connecting portion 36b the distance is taken as L _2, the first link portion 51 so that L ₂ is greater than L ₁ is provided. The second link portion 52 is similarly provided.

The link part 51 on the side connected to the movable drive electrode part 31 with the fulcrum part 61a as a fulcrum is the distance of the first link part 51 from the fulcrum part 61a to the movable drive electrode part 31, that is, the fulcrum part 61a and the first fulcrum part 61a. the distance L ₁ between the connecting portion 36a as the rotation radius, operates to rotate. Further, the link portion 51 on the side connected to the movable capacitance electrode portion 30 is a first link portion from the fulcrum portion 61a to the movable capacitance electrode portion 30 with the fulcrum portion 61a as a fulcrum in conjunction with the movable drive electrode portion 31. 51 distance, that operates to rotate the distance L ₂ between the fulcrum portion 61a and the first connecting portion 36b as a rotational radius. Therefore, as _{L 2} becomes large with respect to _{L 1,} the first link portion 51, the second link unit 52, and by providing the respective fulcrum 61a ~ 61d, the movable drive shown in FIG. 3 (b) The displacement amount ΔD2 of the movable capacitive electrode portion 30 can be made larger than the displacement amount ΔD1 of the electrode portion 31. Therefore, the variable capacitance range of the variable capacitor 10 of this embodiment can be increased.

In the variable capacitor 10 of the present embodiment, when acceleration is applied from the outside, if there is a difference in the moment of inertia between the movable capacitor electrode part 30 and the movable drive electrode part 31, the first fulcrum 61a to 61d is used as the center. A moment of force that the link portion 51 tries to rotate acts. FIG. 4 is a schematic side view for explaining the moment of inertia of the movable capacitance electrode part 30 and the movable drive electrode part 31 of the present embodiment. FIG. 4 shows a state in which the first link portion 51 is stationary by rotating by an angle θ with the fulcrum portion 61a as a fulcrum. Although not shown in FIG. 4, the movable capacitive electrode unit 30 is coupled to the first coupling part 36b, and the movable drive electrode unit 31 is coupled to the first coupling part 36a.

In this state, when an acceleration a is applied in the Z2 direction, an acceleration a ′ (= a × cos θ) is applied in a direction orthogonal to the first link portion 51. Here, with the fulcrum part 61a as a fulcrum, the inertia moment of the movable drive electrode part 31 connected to the first link part 51 is I ₁ , the inertia moment of the movable capacitor electrode part 30 is I ₂ , and the movable drive electrode part 31 the mass _{M 1,} the mass of the movable capacitor electrode 30 and _{M 2.} Further, the mass of the first link portion 51 is assumed to be negligibly small. At this time, it is expressed by approximating I ₁ = L ₁ ² × M ₁ and I ₂ = L ₂ ² × M ₂ . Here, if the balance between the moment of inertia I ₁ and the moment of inertia I ₂ is shifted, a shift occurs in the moment of force generated in the rotation direction (direction of a ′), and the first link portion 51 is rotated to be static. The capacitance value will fluctuate.

In the present embodiment, as shown in FIGS. 3A and 3B, the movable capacitor electrode portion 30 is formed thinner than the movable drive electrode portion 31. Therefore, the mass per unit area of the movable capacitive electrode part 30 is formed to be smaller than the mass per unit area of the movable drive electrode part 31. Therefore, as compared with the case where the movable capacitor electrode portion 130b and the movable drive electrode portion 130a are formed to have the same thickness as in the variable capacitor 111 of the second conventional example shown in FIG. The mass M _{2 of} 30 is reduced. In the present embodiment, the first link portion 51 so that _{L 2} is greater than _{L 1,} together with the second link part 52 and the fulcrum 61a ~ 61d are provided, _{M 2} is from _{M 1} The movable capacitance electrode part 30 and the movable drive electrode part 31 are formed so as to be smaller. Thus, it is possible to reduce the difference between the moment of inertia I ₁ and moment of inertia I _2. Therefore, it is possible to suppress the displacement of the capacitance by suppressing the displacement of the movable capacitance electrode portion 30 and the movable drive electrode portion 31 due to the influence of the acceleration applied from the outside.

In this specification, “mass per unit area” refers to a value obtained by dividing the mass of the entire movable capacitive electrode unit 30 by the area of the surface of the movable capacitive electrode unit 30 facing the fixed unit 20. The same applies to the movable drive electrode portion 31.

Further, it is more preferable to form the movable capacitor electrode portion 30 and the movable drive electrode portion 31 with different thicknesses so that I ₁ = L ₁ ² × M ₁ and I ₂ = L ₂ ² × M ₂ are equal. preferable. By so doing, the moments of inertia of the movable capacitor electrode portion 30 and the movable drive electrode portion 31 are equalized, so that the capacitance fluctuation is reliably suppressed.

It should be noted that the thickness of the movable capacitor electrode portion 30 can be appropriately adjusted and processed by etching such as deep RIE (deep reactive ion etching).

As described above, according to the variable capacitor 10 of the present embodiment, the rotational radius (L ₂ ) of the movable capacitive electrode portion 30 is larger than the rotational radius (L ₁ ) of the movable drive electrode portion 31, and therefore the movable drive electrode When the distance between the portion 31 and the fixed drive electrode portion 20b is displaced, the amount of displacement of the distance between the movable capacitance electrode portion 30 and the fixed capacitance electrode portion 20a can be increased. Therefore, the variable capacitance range of the variable capacitor 10 can be increased. Further, the movable capacitive electrode section 30 has a larger radius of rotation and a smaller mass per unit area than the movable drive electrode section 31. Thereby, the difference of the moment of inertia which arises in the movable capacity electrode part 30 and the movable drive electrode part 31 when acceleration is applied from the outside can be made small. Therefore, it is possible to suppress the displacement of the capacitance by suppressing the displacement of the movable capacitance electrode portion 30 and the movable drive electrode portion 31 due to the influence of the acceleration applied from the outside.

FIG. 5 is a plan view of the variable capacitor 10 in the first modification of the present embodiment. As shown in FIG. 5, the mass M ₂ of the movable capacitive electrode unit 30 can be reduced also by forming a plurality of holes 32 in the movable capacitive electrode unit 30. Even in such an aspect, the difference in the moment of inertia between the movable capacitor electrode portion 30 and the movable drive electrode portion 31 can be reduced, so that the capacitance variation can be suppressed. In addition, when the hole 32 is provided so as to penetrate the movable capacitance electrode portion 30, the area of the movable capacitance electrode 34 (not shown in FIG. 5) forming the capacitance is reduced, and the capacitance may be reduced. In this case, it is preferable to form a plurality of recesses so as not to affect the electrode area of the movable capacitance electrode 34.

FIG. 6 is a cross-sectional view of the variable capacitor 10 in the second modification of the present embodiment. In the variable capacitor 10 in the second modification, the movable capacitor electrode portion 30 and the movable drive electrode portion 31 are formed to have the same thickness. A mass adjusting unit 33 is formed on the movable drive electrode unit 31. Thereby, the mass of the mass adjusting unit 33 is added to the mass M ₁ of the movable drive electrode unit 31, and the inertia moment I ₁ of the movable drive electrode unit 31 is determined by the total mass, so that the inertia moment I ₁ and the inertia The difference from the moment I ₂ can be reduced. The mass adjusting unit 33 is not particularly limited, but can be formed as a thin film using an insulating material such as SiO ₂ .

Further, in the variable capacitor 10 of the present embodiment, the configuration in which the fixed capacitor electrode portion 20a and the fixed drive electrode portion 20b are arranged in the common fixed portion 20 is shown, but the present invention is not limited to this. FIG. 7 is a cross-sectional view of the variable capacitor 10 in the third modification. In the third modification, the configuration of the movable capacitance electrode unit 30, the movable drive electrode unit 31, the first link unit 51, the second link unit 52, and the like is the same as that in FIGS. The difference is that 28 is provided.

As shown in FIG. 7, the protection unit 28 is provided so as to cover the movable capacitance electrode unit 30 and the movable drive electrode unit 31. In addition, the fixed capacitance electrode 24 is provided in the protection portion 28 at a position facing the movable capacitance electrode portion 30. That is, in the variable capacitor 10 of the third modification, the protection unit 28 is provided to function as the fixed capacitance electrode unit 20a. In this case, when a drive voltage is applied between the movable drive electrode 35 and the fixed drive electrode 25, the movable drive electrode portion 31 moves in the Z2 direction, and the movable capacitive electrode portion 30 moves in the Z1 direction. In other words, since the opposing distance between the fixed capacitor electrode 24 and the movable capacitor electrode 34 changes so as to decrease, the capacitance value can be changed so as to increase.

<Second Embodiment>
FIG. 8 is a cross-sectional view of the variable capacitor 11 of the second embodiment. As shown in FIG. 8, in the variable capacitor 11 according to the second embodiment, the movable capacitor electrode portion 80 and the movable drive electrode portion 81 are provided in a common movable portion 82, and the movable portion 82 is joined. It is connected to the fixed part 70 via the support part 71. The fixed portion 70 includes a fixed capacitance electrode portion 70a that faces the movable capacitance electrode portion 80 with a space therebetween, and a fixed drive electrode portion 70b that faces the movable drive electrode portion 81 with a space therebetween. The fulcrum portion 72 is formed so that the movable drive electrode portion 81 and the movable capacitance electrode portion 80 rotate in conjunction with the fulcrum portion 72 as a fulcrum.

When a drive voltage is applied between the fixed drive electrode 75 and the movable drive electrode 85, the movable drive electrode portion 81 is displaced in the Z2 direction with the fulcrum portion 72 as a fulcrum by electrostatic force. In conjunction with this, the movable capacitor electrode part 80 is displaced in the Z1 direction with the fulcrum part 72 as a fulcrum. That is, the distance between the fixed capacitor electrode 74 and the movable capacitor electrode 84 is increased and the capacitance is displaced so as to be reduced.

The rotation radius (the length from the fulcrum part 72 to the end of the movable drive electrode part 81) of the movable drive electrode part 81 of the variable capacitor 11 of the present embodiment is L ₃ , and the rotation radius (fulcrum part) of the movable capacitor electrode part 80. When from 72 to the end portion of the movable capacitor electrode 80 length) and L _4, L _{_4>} L ₃ become as fulcrum portion 72 is provided. Therefore, when the distance between the movable drive electrode portion 81 and the fixed drive electrode portion 70b is displaced, the displacement amount of the distance between the movable capacitance electrode portion 80 and the fixed capacitance electrode portion 70a can be increased. 11 variable capacity ranges can be increased.

In the variable capacitor 11 of the present embodiment, when the mass of the movable drive electrode portion 81 is M ₃ and the mass of the movable capacitance electrode portion 80 is M ₄ , the magnitude of the moment of inertia of the movable drive electrode portion 81 is (M ₃ × L ₃ ² ) / 3, and the magnitude of the moment of inertia of the movable electrode portion 80 is represented as (M ₄ × L ₄ ² ) / 3. In the present embodiment, as shown in FIG. 8, the movable capacitor electrode portion 80 is formed thinner than the movable drive electrode portion 81. That is, the movable capacitor electrode part 80 is formed so as to have a larger radius of rotation than the movable drive electrode part 81 and to have a smaller mass per unit area. Thereby, as in the variable capacitor 111 of the second conventional example shown in FIG. 10, the movable capacitor electrode 130b and the movable drive electrode portion 130a are compared with the case where the thicknesses are formed to be equal. The difference in moment of inertia between the portion 80 and the movable drive electrode portion 81 can be reduced. Therefore, it is possible to suppress the displacement of the capacitance by suppressing the displacement of the movable capacitor electrode portion 80 and the movable drive electrode portion 81 due to the influence of the acceleration applied from the outside.

As a method for reducing the difference in moment of inertia between the movable capacitor electrode unit 80 and the movable drive electrode unit 81, a hole 32 (not shown) or a recess is formed in the movable capacitor electrode unit 80, as in the first embodiment. For example, a method of providing the mass adjusting unit 33 (not shown) in the movable drive electrode unit 81 may be used.

10, 11

Variable capacitor

20, 70 Fixed portion 20a, 70a Fixed capacitance electrode portion 20b, 70b Fixed

drive electrode portion

24, 74

Fixed capacitance electrode

25, 75 Fixed drive electrode 26a, 26b, 26c, 26d, 71 Junction support portion 28

Protection part

30, 80 Movable

capacity electrode part

31, 81 Movable drive electrode part 32 Hole part 33

Mass adjustment part

34, 84

Movable capacity electrode

35, 85 Movable drive electrode 36a, 36b, 36c, 36d First connection part 51 First 52 second link part 61a, 61b, 61c, 61d, 63a, 63b, 72 fulcrum part 65a, 65b, 65c, 65d joint part

Claims

A movable drive electrode portion and a fixed drive electrode portion disposed opposite to each other;
A movable capacitance electrode portion and a fixed capacitance electrode portion disposed to face each other,
In the variable capacitance capacitor formed so that the movable drive electrode portion and the movable capacitance electrode portion are interlocked with a fulcrum portion as a fulcrum,
The movable capacitor electrode part and the movable drive electrode part are connected by a link part provided with the fulcrum part,
When the movable drive electrode part approaches the fixed drive electrode part, the link part is provided so as to be rotatable about the fulcrum part so that the movable capacitive electrode part is separated from the fixed capacitive electrode part. And
With the fulcrum portion as a fulcrum, the rotation radius of the link portion connected to the movable capacitive electrode portion is larger than the rotation radius of the link portion connected to the movable drive electrode portion. The fulcrum part is provided,
The movable capacitor electrode part and the movable drive electrode part are formed so that the mass per unit area of the movable capacitor electrode part is smaller than the mass per unit area of the movable drive electrode part. A variable capacitor.
The product of the square of the rotational radius of the link portion on the side connected to the movable capacitive electrode portion and the mass of the movable capacitive electrode portion is the rotational radius of the link portion on the side connected to the movable drive electrode portion. The variable capacitor according to claim 1, wherein the capacitor is formed so as to be equal to a product of a square of λ and a mass of the movable drive electrode portion.
The movable capacitive electrode part and the movable drive electrode part are formed in a flat plate shape, and the thickness of the movable capacitive electrode part is formed thinner than the movable drive electrode part. The variable capacitor according to claim 2.
The variable capacitor according to any one of claims 1 to 3, wherein a hole is provided in the movable capacitor electrode portion.
The variable capacitor according to any one of claims 1 to 4, wherein a mass adjustment unit is provided in the movable drive electrode unit.
A movable drive electrode portion and a fixed drive electrode portion disposed opposite to each other;
A movable capacitance electrode portion and a fixed capacitance electrode portion disposed to face each other,
In the variable capacitor formed so that the movable drive electrode portion and the movable capacitance electrode portion rotate in conjunction with a fulcrum portion as a fulcrum,
The fulcrum part is provided so that the rotation radius of the movable capacitive electrode part when the fulcrum part is used as a fulcrum is larger than the rotation radius of the movable drive electrode part,
The movable capacitor electrode part and the movable drive electrode part are formed so that the mass per unit area of the movable capacitor electrode part is smaller than the mass per unit area of the movable drive electrode part. A variable capacitor.