JPH06267792A - Variable capacitor - Google Patents

Abstract

PURPOSE:To increase the maximums capacitance of a variable capacitor and at the same time to stabilize the torque of a rotor and the capacitance value to be formed and to facilitate a fine adjustment. CONSTITUTION:This variable capacitor is provided with a stator 2 made up of a ceramic dielectric substance 6 in which a stator electrode 1 to function as a stator-side electrode is formed inside and an external electrode 7 to be electrically connected to the stator electrode 1 is formed outside, a rotor 3 rotatably mounted on the stator 2 to function as a movable-side electrode, a spring 4 for press the rotor 3 against the stator 2, a rotor terminal 5 electrically in continuity to the rotor (movable-side electrode) 3 and a shaft 11 which passes through at least the stator 2 and the rotor 3 and is held so as to be able to slide and rotate with the rotor 3 being pressed against the stator 2 with the elastic force of the spring 4.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention relates to a capacitor,
More specifically, the present invention relates to a variable capacitor capable of adjusting a minute electrostatic capacitance.

[0002]

2. Description of the Related Art For example, in a variable capacitor used as a trimmer capacitor, a dielectric is typically arranged between a stator electrode (fixed side electrode) and a rotor electrode (movable side electrode) which rotates relative to the stator electrode. It has a structure. And as this dielectric, for example, a ceramic dielectric is used.

In such a variable capacitor, in order to widen the capacity adjustment range, it is necessary to increase the maximum capacity that can be acquired. Then, as one of means for increasing the maximum capacity, there is a method of reducing the thickness of the dielectric material disposed between the stator electrode and the rotor electrode. However, when a ceramic dielectric is used as the dielectric, its mechanical strength is relatively low, and therefore there is a limit to reducing the thickness of the dielectric.

In order to solve this problem, either the stator electrode or the rotor electrode is formed inside the ceramic dielectric, and the overall thickness of the ceramic dielectric is increased to improve the mechanical strength. There is a variable capacitor in which the maximum capacitance is increased by making the stator electrode and the rotor electrode face each other through a part of a ceramic dielectric having a small thickness.

Among such variable capacitors, one having a stator electrode formed inside a ceramic dielectric is disclosed in, for example, Japanese Utility Model Publication No. 63-5222. In this variable capacitor, the stator electrode is composed of two semicircular divided electrodes, and the rotor electrode is also composed of two semicircular divided electrodes. Two divided electrodes serving as terminals are electrically connected to the stator made of a ceramic dielectric material having the stator electrodes formed therein.

Therefore, according to this variable capacitor, a total of four capacitances are formed by the two divided electrodes forming the stator electrode and the two divided electrodes forming the rotor electrode. The first capacitance and the second capacitance form one series circuit, and the third capacitance and the fourth capacitance
By forming another one series circuit with the capacity of, the two series circuits are connected in parallel.

[0007]

However, the above conventional variable capacitor has the following problems.

First, the conventional variable capacitor described above has a problem that it is not possible to obtain such a large maximum capacitance. That is, since the stator electrode and the rotor electrode are each composed of divided electrodes, and two of the four formed capacitors are connected in series, the electrodes of 1/4 circle face each other even in the maximum capacity. Only the electrostatic capacity at the time is obtained. In addition, in the conventional normal variable capacitor, the electrostatic capacity when the electrodes of ½ circle face each other becomes the maximum capacity, and therefore, only half the maximum capacity can be obtained as compared with this.

Further, since the stator electrode and the rotor electrode are respectively divided electrodes, the rotation angle of the rotor from the minimum capacity to the maximum capacity is 90 °, and when the rotation angle is 180 °, the minimum capacity to the maximum capacity. There is a problem that the effective rotation range in the capacity adjustment is smaller than that of the conventional normal variable capacitor having the capacity of, and the fine adjustment is so difficult.

An elastic body is used to press the rotor and the stator into pressure contact with each other. However, the elastic body such as rubber is
There is a problem in that the heat resistance and the weather resistance are not always sufficient, which causes a decrease in the durability of the variable capacitor as a whole.

The present invention is intended to solve the above-mentioned problems, in that the maximum capacitance formed is large, the torque and capacitance of the rotor are excellent in stability, and moreover, fine adjustment is easy. The purpose is to provide a capacitor.

[0012]

In order to achieve the above object, a variable capacitor of the present invention has a stator electrode formed therein which functions as a fixed-side electrode, and is externally electrically connected to the stator electrode. A stator made of a ceramic dielectric having electrodes formed thereon and rotatably mounted on the stator, made of metal or having an electrode formed on at least a part of an insulator, which functions as a movable electrode. A rotor, a spring member arranged on the upper surface side of the rotor and pressing the rotor to the stator, a rotor terminal electrically connected to the rotor (movable side electrode), and penetrating at least the stator and the rotor,
A shaft for slidably rotating the rotor in a state of being pressed against the stator by the elastic force of the spring member.

[0013]

In the variable capacitor according to the present invention, the stator electrode and the rotor (in the case of the rotor in which an electrode is formed on a part of the insulator, the rotor electrode) function as a fixed side electrode and a movable side electrode and are adjustable. A capacitance is formed between the two, and this capacitance is taken out by the external electrode of the stator and the rotor terminal.

In the variable capacitor of the present invention, the stator electrode and the rotor (movable side electrode) are not divided into two parts as in the conventional variable capacitor described above, and therefore the rotor and the stator having the same size are formed. When used, the maximum capacity can be about twice as large as that of the conventional variable capacitor, so that it is possible to cope with an increase in capacity and to reduce the size when the capacity is the same.

Further, it is possible to adjust the size of the capacity formed by rotating the rotor by 180 ° between the maximum and the minimum, which improves the resolution and facilitates fine adjustment of the capacity. You will be able to do it. That is, in the relationship between the rotation angle of the rotor and the size of the formed capacity, one peak (peak) is formed during the rotation of the rotor by 360 °, and the effective rotation range becomes large. Adjustment can be easily performed.

Further, since the rotor is pressed against the stator by the elastic force of the spring member and is slidably held on the stator, the contact state between the rotor and the stator is stabilized, and the torque and the formation of the rotor are stabilized. The size of the electrostatic capacitance is stabilized.

[0017]

Embodiments of the present invention will be described below with reference to the drawings. 1A and 1B are views showing a variable capacitor according to an embodiment of the present invention. FIG. 1A is a plan view, FIG. 1B is a front sectional view, and FIG. 1C is a bottom view.

The variable capacitor of this embodiment is provided with a stator 2 having a stator electrode 1, a metallic rotor 3 disposed on the upper surface side of the stator 2, and a rotor 3 having a stator 2.
Metal spring member (spring washer) for pressure contact with
4 and a rotor terminal 5 electrically connected to the rotor (movable side electrode) 3.
And a shaft 1 that penetrates at least the stator 2 and the rotor 3 and presses the rotor 3 against the stator 2 by the elastic force of the spring member 4 and slidably holds the rotor 2 on the stator 2.
1 and the rotor terminal 5 is formed by pulling the lower end of the shaft 11 through the bottom surface of the stator 2 to the end of the stator 2.

The stator 2 is composed of a ceramic dielectric 6 and has a hole 1 through which the shaft 11 penetrates in the central portion.
2 is formed, and one stator electrode 1 extending from the substantially central portion to one end portion is formed inside (see FIG. 2). And the stator electrode 1 of the stator 2
The external electrode 7 is formed at the end of the side from which is drawn out, and is electrically connected to the stator electrode 1. The external electrodes 7 can be formed by various known methods such as a method of coating and baking a conductive paste. Further, the lower surface of the stator 2 has a recess 2a (FIG. 1) into which the rotor terminal 5 drawn out from the lower end of the shaft 11 is fitted.
(B) and (c) are formed.

The stator 2 can be manufactured by a method of laminating and sintering an electrode layer and a ceramic dielectric layer (ceramic green sheet) according to a method of forming a monolithic ceramic capacitor. It can be manufactured by other methods.

The recess 2a can be formed, for example, by the method described below. That is, when the ceramic green sheets on which the electrode patterns to be the stator electrodes are printed are stacked and the stator is formed by firing the stacked layers, a predetermined number of ceramic green sheets at predetermined positions (positions where the recesses 2a are to be formed) are formed. ) Is printed with a material that is burnt out during firing, for example, carbon paste is laminated, pressure-bonded and then fired to burn off the carbon paste, and the recessed portion 2a of the sintered body (stator) is to be formed at a position where it should be formed. Forming a portion in which a plurality of hollow layers and thin ceramic dielectric layers are alternately arranged inside, and crushing and polishing this portion by a method such as barrel polishing to form a recess 2a at a predetermined position. You can According to this method, the recess 2a can be easily formed at a predetermined position of the stator 2.

However, the method of forming the stator 2 and the recess 2a is not limited to this, and other methods can be used.

The rotor 3 is made of metal such as brass. As shown in FIGS. 3 (a) and 3 (b), a hole 13 through which the shaft 11 penetrates is formed in the center and the upper surface of the rotor 3 is also formed. On the side, a plus type groove (driver groove) 8 for rotating the rotor 3 from the outside with a tool such as a screwdriver is formed. Further, substantially half (a semicircular portion) 9 of the surface of the rotor 3 facing the stator 2 projects, and the projecting portion 9 substantially functions as a rotor electrode. An arcuate ridge 3a is formed on the peripheral portion of the retracted portion 10 of the surface of the rotor 3 facing the stator 2 so that the rotor 3 can rotate smoothly. It should be noted that it is possible to provide a protrusion at a predetermined position instead of the ridge 3a.

Further, the shaft 11 penetrates the stator 2, the rotor 3 and the spring member 4, and its upper end 11a is crimped so as to engage with the spring member 4.

The lower end portion of the shaft 11 is pulled out to the end portion of the stator 2 to form the rotor terminal 5. This rotor terminal 5 is the shaft 1
1, and is electrically connected to the rotor 3 via the spring member 4.

In the variable capacitor constructed as described above, the stator electrode 1 and the rotor 3 function as a fixed electrode and a movable electrode, respectively, and an adjustable capacitance is formed between them. This electrostatic capacitance is taken out to the outside by the external electrode 7 and the rotor terminal 5 which are electrically connected to the stator electrode 1.

Then, in this variable capacitor,
Unlike the conventional variable capacitor described above, the stator electrode 1 and the rotor (electrode) 3 are not divided into two parts. Therefore, the maximum capacity when the rotor and the stator of the same size are used is the conventional variable capacitor described above. Since it can be approximately doubled, it is possible to cope with an increase in capacity, and it is possible to reduce the size when the capacity is the same.

Further, it becomes possible to adjust the size of the capacity formed by rotating the rotor 3 by 180 ° between the maximum and the minimum, which improves the resolution and facilitates the fine adjustment of the capacity. Will be able to. That is,
In the relationship between the rotation angle of the rotor 3 and the size of the formed capacity, one peak is formed during the rotation of the rotor by 360 °, and the adjustment accuracy is improved.

Further, since the rotor 3 is pressed against the stator 2 by the spring member 4, the rotor 3 and the stator 2 are
The contact state between and is stable, and the torque of the rotor 3 and the magnitude of the formed electrostatic capacitance can be stabilized. Further, the metal spring member 4 is excellent in heat resistance and weather resistance, and can have sufficient durability.

Further, since the shaft 11 and the rotor terminal 5 are integrally formed, the number of parts can be reduced and the manufacturing cost can be reduced.

In the above embodiment, the stator 2
The case where the recess 2a is formed on the lower surface side of the stator 2 has been described. However, without forming the recess 2a on the lower surface side of the stator 2, the rotor terminal is provided from the lower end of the shaft 11 through the flat lower surface of the stator 2 to the end thereof. It can also be configured to withdraw.

FIG. 4 is a sectional view showing a variable capacitor according to another embodiment of the present invention, (a) is a plan view, (b) is a front sectional view, and (c) is a bottom view. .

In the variable capacitor of this embodiment,
As the stator 2, as shown in FIG. 5, a stator in which a pair of stator electrodes 1a and 1b are formed symmetrically is used. And the stator electrode 1
a is connected to the external electrode 7a on one end side of the stator 2, the stator electrode 1b is connected to the external electrode 7b on the other end side of the stator 2, and the stator electrode 1b and the external electrode 7b are dummy (electrodes). There is. Since the configuration of the other parts is the same as that of the variable capacitor of the above-described embodiment shown in FIG. 1, the description of the related parts is cited and the description thereof is omitted.

In the variable capacitor of this embodiment,
Inside the stator 2, a pair of substantially symmetrical stator electrodes 1
Since a and 1b are formed and external electrodes 7a and 7b that are electrically connected to the stator electrodes 1a and 1b are formed at substantially symmetrical positions on both ends of the outside, the direction of the stator 2 in the assembly process is increased. Therefore, the manufacturing process can be simplified.

Further, since the external electrodes 7a and 7b of the stator 2 are a pair (two) and are bilaterally symmetrical, reliability of soldering to the substrate at the time of mounting can be improved.
Further, in other respects, the same effects as those of the variable capacitor of the above embodiment can be obtained.

6A and 6B are views showing still another embodiment of the present invention, in which FIG. 6A is a plan view and FIG. 6B is a front sectional view.
(C) is a bottom view.

In the variable capacitor of this embodiment,
Rather than pulling out the lower end of the shaft 11 to form the rotor terminal 5, a rotor extraction electrode (broadly defined rotor terminal) 5 a that is electrically connected to the rotor 3 is formed inside the stator 2. The rotor extraction electrode 5a is connected to the external electrode 7b formed at the end of the stator 2. Since the configuration of the other parts is the same as that of the variable capacitor of the above-described embodiment shown in FIG.

In the variable capacitor of this embodiment,
Since the rotor lead-out electrode (rotor terminal) 5a that is electrically connected to the rotor 3 is formed inside the stator 2, it is not necessary to draw the lower end of the shaft 11 to one end of the stator 2. Therefore, in the assembly process, the orientation of the shaft 11 is eliminated, and the manufacturing process can be simplified. Further, since the external electrodes 7a and 7b of the stator 2 are a pair (two) and are bilaterally symmetrical, the reliability of soldering to the substrate at the time of mounting can be improved.
Further, in other respects, the same effects as those of the variable capacitor of the above embodiment can be obtained.

In each of the above embodiments, the rotor 3
As described above, the case of using a metal rotor has been described. As the rotor, in addition to the metal rotor, at least a part of an insulator such as alumina (for example, a part of a surface facing the stator) is used. It is also possible to use a rotor metallized by a method such as plating, that is, a rotor in which electrodes are formed on a part of an insulator.

In each of the above embodiments, the case where the spring washer is used as the spring member 4 has been described.
The spring member is not limited to this, and another spring member such as a coil spring can be used by appropriately changing the shape of the shaft.

The variable capacitor of the present invention is not limited to the above embodiment in other points as well, and the specific shapes and arrangement positions of the stator and the stator electrode, the shape of the metallic rotor, and the like. Various applications and modifications can be made within the scope of the invention with respect to the constituent material, the metallizing method in the case of using the metallized rotor, the specific shape of the shaft, the constituent material, and the like.

[0042]

As described above, in the variable capacitor of the present invention, the stator electrode is formed inside and the external electrode that is electrically connected to the stator electrode is formed outside, and the variable capacitor is rotatable on the stator. The mounted rotor, the spring member disposed on the upper surface side of the rotor for pressing the rotor to the stator, the rotor terminal electrically connected to the rotor, the stator and the rotor, and the elastic force of the spring member presses the rotor to the stator. Since it is configured to include a shaft that holds the rotor in a slidable and rotatable state, the pressure contact force (that is, the joined state) between the rotor and the stator is stabilized, and the torque of the rotor and the generated electrostatic force are stabilized. The size of the capacitance can be stabilized, a large capacitance can be obtained, and in the case of the same capacitance, downsizing can be achieved.

Further, the relationship between the rotation angle of the rotor and the change rate of the formed capacitance, that is, the rate of capacitance change with respect to the rotation angle can be reduced to facilitate fine adjustment of the capacitance.

[Brief description of drawings]

1A and 1B are views showing a variable capacitor according to an embodiment of the present invention, in which FIG. 1A is a plan view, FIG.
(C) is a bottom view.

FIG. 2 is a plan view showing a stator that constitutes a variable capacitor according to an embodiment of the present invention.

3A and 3B are diagrams showing a rotor of a variable capacitor according to an embodiment of the present invention, FIG. 3A is a perspective view showing an upper surface side thereof, and FIG. 3B is a perspective view showing a lower surface side thereof.

4A and 4B are diagrams showing a variable capacitor according to another embodiment of the present invention, FIG. 4A is a plan view, FIG. 4B is a front sectional view, and FIG. 4C is a bottom view.

5 is a plan view showing a stator that constitutes the variable capacitor of FIG. 4. FIG.

6A and 6B are diagrams showing a variable capacitor according to still another embodiment of the present invention, FIG. 6A is a plan view, FIG. 6B is a front sectional view, and FIG. 6C is a bottom view.

[Explanation of symbols]

 1 Stator Electrode 2 Stator 2a Recess 3 Rotor 4 Spring Member 5 Rotor Terminal 6 Ceramic Dielectric 7 External Electrode 8 Driver Groove 11 Shaft 11a Upper End of Shaft

Claims (1)

[Claims] 1. A stator made of a ceramic dielectric material, wherein a stator electrode that functions as a fixed-side electrode is formed inside, and an external electrode that is electrically connected to the stator electrode is formed outside, and a stator that rotates on the stator. A rotor that is movably attached and that is made of metal or has an electrode formed on at least a part of an insulator and that functions as a movable electrode; and a rotor that is disposed on the upper surface side of the rotor and that has the stator as the stator. A spring member to be pressed into contact with the rotor, a rotor terminal electrically connected to the rotor (movable side electrode), a rotor terminal that penetrates at least the stator and the rotor, and is slid in a state where the rotor is pressed against the stator due to an elastic force of the spring member. A variable capacitor, comprising: a shaft that is rotatably held.