JPS5938041Y2 - variable capacitor - Google Patents

Description

[Detailed explanation of the idea] The present invention relates to improvements in variable magnetic capacitors.

Variable ceramic capacitors have good temperature and frequency characteristics, and have the advantage of being small and inexpensive to manufacture.
VHF or UHF tuner, electronic tuning tuner, 1
It has come to be widely used for tuning of consumer equipment such as M tuners or communication equipment, tuning of oscillation circuits, matching circuits, probe circuits, etc., and capacitance correction.

1A and 1B show an example of a conventional variable magnetic capacitor, FIG. 1A is an exploded perspective view thereof, and FIG. 1B is an assembled sectional view.

As shown in the figure, the conventional variable ceramic capacitor has a disk-shaped rotor 1 made of dielectric ceramic with a high dielectric constant, and
A rotating shaft 30 head 3 having a semicircular electrode 2 fixed thereon and made of a conductor passed through the rotor 1 through approximately the axial center thereof.
A is fixed to the electrode 2 by soldering or other means, and the rotating shaft 3 is inserted into the center hole 4a of the stator 4 made of porcelain such as 7-orsterite or steatite to connect the rotor 1 and the stator. 4 are placed in opposition to each other.

A semicircular stator electrode 6 having a stator terminal 5 integrally formed thereon is provided on the end face of the stator 4 on the rotor side.

The stator electrode 6 is made by bonding and embedding a Kovar metal plate or the like in a recess previously provided on the surface of the stator 40, and then polishing the surface to make it optically flat. This forms a flat contact surface.

On the other hand, a ring-shaped elastic body 7 such as a silicone packing is inserted into the tip of the rotating shaft 3 that penetrates the stator 4 and protrudes from the lower surface thereof, and a ring-shaped attachment part 8 is placed on the elastic body 7.
The rotor 1 is stacked with rotor terminals 9 having a
and the stator 4 are elastically held using the elastic force of the elastic body 70.

Note that the rotating shaft 3 is caulked so that it is electrically conductive to the rotor terminal 9 and can be rotated within the mounting portion 8 with an appropriate torque.

In the variable magnetic capacitor described above, the contact surface between the rotor 1 and the stator electrode 6 is finished to be optically flat, so as long as the bonding state between the two is kept optically flat, the capacitance-rotation angle characteristic capacitance - It can be expected to have good linearity of temperature characteristics, good creep characteristics, high Q, and excellent frequency characteristics.

However, the shrinkage ratio of the adhesive 10 interposed between the stator 4 and the stator electrode 6 is such that the rotor 1 made of porcelain and the stator 4
The shrinkage ratio of the rotor 1 and the stator electrode 6 made of metal material is more than one order of magnitude larger than that of the stator electrode 6, which is made of a metal material.
The adhesive 10 contracts more than the stator 4 and the stator electrode 6, and the upper surface position of the stator electrode 6 lowers as indicated by the dotted line A in FIG. 1B.

For this reason, the gap g1 between the contact surface between the rotor 1 and the stator electrode 6 increases, the capacitance decreases, and the capacitance-temperature sensitivity is significantly reduced in the low temperature region, as shown by the solid line L1 in FIG. This method has the disadvantage of exhibiting severe nonlinearity.

The present invention eliminates the above-mentioned conventional drawbacks, and even when the adhesive shrinks due to temperature, the capacitance does not decrease, and the linearity of the capacitance-temperature characteristic can be maintained in the low temperature region 1. The purpose is to provide highly reliable variable capacitors.

In order to achieve the above object, the present invention provides a variable capacitor in which a stator electrode is bonded to one side of the stator, and a rotor rotatably fixed to the stator is rotated on the stator electrode. It is characterized by having a concave portion serving as an adhesive filling portion and a convex portion serving as an opposing portion at the joint portion with the adhesive material.

DESCRIPTION OF THE PREFERRED EMBODIMENTS The content of the present invention will be specifically described below with reference to the accompanying drawings, which are examples.

FIG. 3A is a partial plane cross-sectional view of the variable capacitor according to the present invention, and FIG. 3B is a partially enlarged cross-sectional view taken along line B1-B1 in FIG. 4A.

In this embodiment, a plurality of oblique convex portions 12 having the same height Hl are provided radially at intervals on the bottom surface of the concave portion of the stator 4 made of steatite, forsterite, etc. The lower surface of the stator electrode 6 is brought into contact with the tip of the portion 12, and an adhesive 10 is filled in the recess 13 formed between the convex portions 12, and the stator electrode 6 is bonded to the stator 4 with the adhesive 10. It is.

The convex portion 12 does not necessarily have to be oblique, but may be trapezoidal or rectangular, for example, and instead of being provided radially, it may be provided concentrically in an arc shape with respect to the axis. may be provided on the stator electrode 6 instead of being provided on the stator 4.

With the above-described structure, even if the adhesive 10 contracts as shown by the dotted line in FIG. The position of is kept constant.

As a result, the gap g1 at the contact surface between the rotor 1 and the stator electrode 6 is kept constant regardless of temperature fluctuations, and a decrease in capacitance is prevented. It shows a high degree of linearity as shown in .

As described above, the present invention provides a variable capacitor in which a stator electrode is bonded to one side of the stator, and a rotor rotatably fixed to the stator is rotated on the stator electrode. Since the bonding part has a concave part serving as an adhesive filling part and a convex part serving as a contact part, the capacitance can be reduced even if the adhesive contracts due to temperature fluctuations. Therefore, it is possible to provide a highly reliable variable capacitor that can maintain the custom-made capacitance-temperature linearity in the low temperature region 1.

[Brief explanation of drawings]

Figure 1A is an exploded perspective view of a conventional variable capacitor Figure 1B
2 is a capacitance-temperature characteristic diagram of the variable capacitor, FIG. 3A is a partial plane sectional view of the variable capacitor according to the present invention, and FIG. 3B is B1- of FIG. 3A. It is a partially enlarged sectional view taken on line B1. 1... Rotor, 10... Adhesive material, 3... Rotating shaft,
12... Convex part, 4... Stator, 13... Concave part,
6... Stator electrode.

Claims (2)

[Scope of utility model registration request] (1) In a variable capacitor in which stator electrodes are bonded to two sides of the stator, and a rotor rotatably pivoted to the stator is rotated on the stator electrodes, the stator electrodes are bonded to the joint portion of the stator and the stator electrodes. A variable capacitor characterized by having a concave portion serving as a material filling portion and a convex portion serving as a contact portion. (2) The variable capacitor according to claim 1, wherein a plurality of the convex portions are provided radially at intervals. (○) The variable capacitor according to claim 2, wherein the convex portion has an oblique shape.