JPH0612743B2 - Variable capacitor - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a variable capacitor such as a trimmer capacitor, and more particularly to a variable capacitor having an improved structure of components.

SUMMARY OF THE INVENTION The present invention provides a variable capacitor, in which the rotor electrode formed on the rotor is formed of a common metal plate together with a spring that applies a desired torque to the rotation of the rotor. It is intended to reduce the number and simplify the assembly process.

[Prior Art] FIG. 9 is a sectional view showing an example of a conventional trimmer capacitor. Such a trimmer capacitor is disclosed in, for example, Japanese Patent Laid-Open No. 59-46017.

The trimmer capacitor shown here is of a type housed in a case 1 made of resin. The case 1 is molded with one end of each of the rotor-side terminal 2 and the stator-side terminal 3 received in a mold. Rotor side terminal 2
Has integrally formed a shaft 4 whose inside is filled with the resin forming the case 1. The end of the stator-side terminal 3 inside the case 1 is exposed from the bottom surface of the case 1.

The upper end of the shaft 4 shown in FIG. 9 is deformed into a flange shape as a result of being caulked. At the stage of incorporating a predetermined component in the case 1, the shaft 4 has a uniform cylindrical shape up to its upper end. When assembling various parts in the case 1, it is performed as follows.

First, the dielectric plate 5 forming a part of the stator-side member is placed on the bottom of the case 1. The dielectric plate 5 has a stator electrode 6 formed on a part of its lower surface. The dielectric plate 5 is
When placed in the case 1, the rotation of itself is prohibited.

Next, the rotor 7 made of metal is placed on the dielectric plate 5. The rotor 7 has a stator electrode 6 via a dielectric plate 5.
The rotor electrode 8 that faces is formed integrally. The rotor 7 receives the above-mentioned shaft 4 at its center and is rotatably held with respect to the dielectric plate 5. The rotor 7 has an auxiliary electrode 9 protruding on the side opposite to the side on which the rotor electrode 8 is formed. The auxiliary electrode 9 serves to prevent a tilt of the rotor 7 by absorbing a step generated by the formation of the rotor electrode 8. A groove 10 is provided on the upper surface of the rotor 7.

The spring 11 is arranged so as to engage with the groove 10 of the rotor 7. The spring 11 is mechanically fixed to the driver plate 12 in advance by caulking. The driver plate 12 is provided with an adjusting groove 13 with which the tip of a driver or the like used in the adjusting operation is engaged.

When the above assembling process is completed, as shown in FIG. 9, the upper end of the shaft 4 is crimped and deformed into a flange shape, whereby the dielectric plate 5, the rotor 7, the spring 11 and the driver plate. Each of the components 12 is prevented from slipping out of the case 1, and the force of the spring 11 is exerted in the direction in which the rotor electrode 8 is brought into close contact with the dielectric plate 5.

In such a configuration, when the tip of a driver or the like is fitted into the adjusting groove 13 of the driver plate 12 and a rotational force is applied to the tip, the rotor 7 is rotated via the spring 11. Therefore, the facing area between the rotor electrode 8 and the stator electrode 6 is changed, and the capacitance formed between the two is changed. This variable capacitance is obtained by connecting the rotor-side terminal 2 that forms the shaft 4 electrically connected to the rotor electrode 8 via the spring 11 and the driver plate 12 and the stator-side terminal 3 that contacts the stator electrode 6. Taken out by and.

[Problems to be Solved by the Invention] The conventional trimmer capacitor described above encounters some problems during its manufacturing process. First of all, it must be taken into consideration that such a trimmer capacitor is usually extremely small with an outer diameter of about 4 to 5 mm.

Considering the extremely small size of such a trimmer capacitor as described above, for example, the spring 11
It is understood that the work of integrating the driver plate 12 and the driver plate 12 by caulking is extremely difficult. In addition, the integrated spring 11 and driver plate 12
Is placed on the rotor 7, and in this state, the spring 11
Is properly aligned and fitted in the groove 10 of the rotor 7,
The work of caulking the upper end of the shaft 4 while maintaining this requires skill and is time-consuming and inefficient.

Therefore, the present invention is intended to provide a variable capacitor that can further simplify the assembly process.

[Means for Solving the Problems] The present invention relates to a stator-side member including a stator electrode and a dielectric plate while a rotor forming a rotor electrode is held by a shaft electrically connected to the rotor electrode. Rotatably mounted so that the rotor electrode faces the stator electrode across a part of the dielectric plate, and as a result, a variable capacitance corresponding to the facing area between the rotor electrode and the stator electrode. And the capacitance is extracted by the rotor-side terminal electrically connected to the shaft and the stator-side terminal electrically connected to the stator electrode, and the direction in which the rotor electrode closely contacts the dielectric plate is formed. In the variable capacitor in which the spring for biasing the rotor is provided in the state of being engaged with the shaft, the above-mentioned problems are solved as follows.

First, both the rotor electrode and the spring are formed of a common metal plate, and the metal plate is bent, and the rotor electrode is formed on one side and the spring is formed on the other side through the bending line.

Further, the rotor is made of a resin that fills a portion of the metal plate on the rotor electrode side with the rotor electrode exposed, and the resin has a surface flush with the surface of the rotor electrode at a position adjacent to the rotor electrode. Form.

[Advantageous Effects of the Invention] In the variable capacitor according to the present invention, the rotor electrode is formed from the same metal plate by bending the metal plate forming the spring. Then, in order to allow the rotor electrode to stably contact the dielectric plate, the portion of the metal plate on the rotor electrode side is filled with resin, and this resin makes the surface flush with the rotor electrode. It is formed at an adjacent position. From these facts, all the parts on the rotor side in the variable capacitor can be handled as one body. Here, the number of parts required in the assembling process of the variable capacitor is reduced, and the assembling work can be simplified. These things lead to cost reduction of the variable capacitor.

[Embodiment] An embodiment in which the present invention is applied to a trimmer capacitor is shown in FIG. 1 and FIG. 1 is a top view and FIG. 2 is a sectional view taken along the line II-II in FIG.

In particular, as is clear from comparing FIG. 2 with FIG. 9 described above, the case 21 and the rotor side terminal 2 in this embodiment are shown.
2, stator side terminal 23, shaft 24, dielectric plate 25
The stator electrode 26 is substantially the same as the case 1, rotor side terminal 2, stator side terminal 3, shaft 4, dielectric plate 5 and stator electrode 6 in the conventional trimmer capacitor shown in FIG. Among these configurations, the only difference is that the wall thickness of the bottom wall of the case 21 is formed thinner than that of the case 1 of the conventional example.

A feature of this embodiment is a configuration related to a rotor assembly 27 placed on the dielectric plate 25. The rotor assembly 27 includes a rotor 28 made of resin and a spring 29 made of a common metal plate. And a rotor electrode 30. The rotor assembly 27 including the rotor 28, the spring 29, and the rotor electrode 30 is handled as an integral body when assembled in the case 1. Hereinafter, details of the configuration of the rotor assembly 27 will be described along with the manufacturing process thereof with reference to FIGS. 3 to 8.

First, the common metal plate 31 forming the spring 29 and the rotor electrode 30 is shown in FIGS. 3 and 4. Such a metal plate 31 is usually taken out in large numbers from a suitable elastic hoop material, and a part of it is treated as the rotor assembly 27 as shown in FIG. 2 as shown in FIG. In addition, the connection strip 32 formed of a part of the hoop material keeps a large number of connected pieces.

3 is a bottom view of the metal plate 31, and FIG. 4 is a sectional view taken along the line IV-IV in FIG. The metal plate 31 is
A disk-shaped portion 29a to be the spring 29 and a substantially semicircular portion 30a to be the rotor electrode 30 are formed, and these are connected to each other by a connecting portion 33. The portion 30a to be the rotor electrode 30 is formed as a part of a ring having a substantially circular planar shape, and a plurality of positioning pieces 34 embedded in the resin of the rotor 28, which will be described later, are formed therein. As can be seen from FIG. 4, the portion 30a to be the rotor electrode 30 is in a state of protruding downward.

Next, as shown in FIGS. 5 and 6, the rotor 28 is formed by resin molding so as to embed the portion 30a of the metal plate 31 to be the rotor electrode 30. Note that FIG. 5 shows the metal plate 31 from above, and FIG. 6 is a sectional view taken along line VI-VI in FIG.

With the portion 30a of the metal plate 31 to be the rotor electrode 30 inserted in the mold for molding the rotor 28, the rotor 2
Molding of 8 is performed. When the rotor 28 is molded,
The lower surface of the portion 30 a is exposed from the rotor 28 while being embedded in the resin forming the rotor 28. The positioning piece 34 is embedded in the rotor 28 so that the rotor 28 holds the metal plate 31 more reliably. The rotor 28 as a whole is in the shape of a container having an opening at the upper side, and in the side wall portion thereof, adjusting grooves 35, 36 that open upward are formed to extend in a cross shape.
A through hole 37 is provided in the bottom wall of the rotor 28.

At the same time as the molding step of the rotor 28 described above or in another step, the portion 29a to be the spring 29 is provided with a curved shape as shown in FIG. This is to facilitate elastic deformation when the portion 29a is used as the spring 29.

Next, as shown in FIGS. 7 and 8, bending is performed at the connecting portion 33 of the metal plate 31. 7. FIG. 7 is a view showing the rotor 28 from above, and FIG. 8 is a sectional view taken along the line VIII-VIII in FIG. As shown by a dotted line and an arrow in FIG. 8, the metal plate 31 has a portion 29 a to be the spring 29, which is bent through a bending line 38 along the root of the connecting portion 33, so that the upper surface of the rotor 28 is prevented. Can be folded into. In this way, the rotor assembly 27 shown in FIGS. 1 and 2 is almost completed, after which the metal plate 31 is connected to the connecting strip 32.
Is cut along the cutting line 39 so as to be separated from. Further, the lower surface of the rotor 28 is polished so that the rotor 2
8 and the lower surface of the rotor electrode 30 are processed to give higher flatness.

The rotor assembly 27 thus obtained has the first
As shown in FIGS. 2 and 3, the dielectric plate 25 is placed on the dielectric plate 25, and then the upper end of the shaft 24 is caulked to be engaged with the spring 29. In this state, the rotor assembly 27 is rotatably held around the shaft 24, and is urged by the spring 27 in the direction in which the rotor electrode 30 is in close contact with the dielectric plate 25.

In the trimmer capacitor shown in FIG. 1 and FIG. 2, the variable capacitance formed between the rotor electrode 30 and the stator electrode 26 in correspondence with the facing area between the two is the rotor side terminal 22 and the variable capacitance. It is taken out by the stator side terminal 23. That is, the rotor electrode 30 is in a state of being electrically connected to the rotor side terminal 22 integrated with the shaft 24 by the spring 29 integrated with the rotor electrode 30 engaging with the shaft 24. On the other hand, the stator electrode 26 is in direct contact with the stator-side terminal 23 and is electrically connected to the stator-side terminal 23.

Although the present invention has been described above with reference to the illustrated embodiments, several modifications can be considered within the scope of the present invention.

For example, the rotor side terminal 22 and the stator side terminal 23
Has been extended in the radial direction, but it may be cut into an appropriate length and bent along the lower surface of the case 21 so that it can be used as a so-called chip-type trimmer capacitor.

Further, as the means for engaging the spring 29 with the shaft 24, the method of caulking the upper end portion of the shaft 24 is adopted. However, other parts may be attached to the upper end portion of the shaft to engage with the spring. Good.

Further, the resin forming the rotor 28 is in contact with the rotor electrode 30 without any gap to form the lower surface of the rotor 28.
Some gap may be formed between the rotor electrode 30 and the resin of the rotor 28.

Further, in the illustrated embodiment described above, there is no equivalent to the auxiliary electrode 9 of the conventional example shown in FIG. Therefore, there is an advantage that the minimum capacitance obtained by this trimmer capacitor can be set to a smaller value and damage to the dielectric plate due to the protrusion of the auxiliary electrode 9 can be prevented. However, if the former advantage is not particularly desired, the auxiliary electrode may also be formed in the variable capacitor according to the present invention, for example, by drawing a metal plate. Incidentally, such an auxiliary electrode, on the other hand,
There may be an advantage that the accuracy of polishing the lower surface of the rotor assembly can be improved.

Further, in the illustrated embodiment, the rotor-side terminal 22 and the shaft 24 are integrally formed, but they may be configured by separate parts.

Further, although the stator electrode 26 is directly formed on the dielectric plate 25, a stator electrode member incorporated separately from the dielectric plate may be used.

Further, the trimmer capacitor shown in the figure is of a type including the case 21, but the present invention can be applied to a type of trimmer capacitor not including the case.

Further, the present invention can be applied to general variable capacitors other than trimmer capacitors with the same structure.

[Brief description of drawings]

FIG. 1 is a top view showing a trimmer capacitor as one embodiment of the present invention. FIG. 2 is a sectional view taken along the first line II-II. FIG. 3 is a bottom view of the metal plate 31 for forming the spring 29 and the rotor electrode 30. FIG. 4 is a sectional view taken along line IV-IV in FIG.
FIG. 5 is a top view showing a state in which the rotor 28 is formed on the metal plate 31 by resin molding. FIG. 6 shows the line of FIG.
It is sectional drawing which follows VI-VI. FIG. 7 is a top view showing a state in which the metal plate 31 is bent and the spring 29 is placed on the rotor 28. FIG. 8 is a sectional view taken along the line VIII-VIII in FIG. 7. FIG. 9 is a sectional view showing a conventional trimmer capacitor. In the figure, 22 is a rotor side terminal, 23 is a stator side terminal, 24 is a shaft, 25 is a dielectric plate, 26 is a stator electrode, 27 is a rotor assembly, 28 is a rotor, 29 is a spring, 30 is a rotor electrode, and 31 is a rotor electrode. The metal plate 38 is a bending line.

Claims (1)

[Claims] 1. A rotor forming a rotor electrode is rotatably attached to a stator-side member including a stator electrode and a dielectric plate while being held by a shaft electrically connected to the rotor electrode. Is opposed to the stator electrode by sandwiching a part of the dielectric plate, thereby forming a variable capacitance between the rotor electrode and the stator electrode, which corresponds to the facing area of the two, and the capacitance is , A spring that is taken out by a rotor-side terminal electrically connected to the shaft and a stator-side terminal electrically connected to the stator electrode, and further urges the rotor in a direction in which the rotor electrode closely contacts the dielectric plate. In the variable capacitor provided in a state of being engaged with, both the rotor electrode and the spring are formed of a common metal plate, and the metal plate is , A rotor electrode is formed on one side and a spring is formed on the other side through the bending line, and the rotor further includes a portion on the rotor electrode side of the metal plate with the rotor electrode exposed. A variable capacitor, comprising a resin to be embedded, the resin having a surface flush with the surface of the rotor electrode formed adjacent to the rotor electrode.