JPS638114Y2 - - Google Patents

Description

[Detailed description of the invention] This invention is a small variable capacitor, in detail, multiple rotor plates and multiple stator plates are meshed alternately, and a dielectric material such as polyethylene film is placed between the rotor plate and the stator plate. Regarding small variable capacitors with film interposed,
The purpose is to provide a small variable capacitor that is highly effective in suppressing howling.

In this type of small variable capacitor, an annular rotor washer and a roughly semicircular rotor plate having a rotor shaft through hole are alternately inserted and stacked on the rotor shaft, and a nut is fastened to the rear end of the rotor shaft. , the rotor plate and rotor washer are fixed to the rotor shaft. The rotor plates are usually divided into groups of multiple plates: AM antenna input stage, AMOSC stage, FM antenna input stage,
It is divided into sections such as FMOSC stage, and in each section, two
Compared to the two rotor plates (capacity adjustment plates for tracking adjustment, etc.), the inner rotor plate has the same shape but is thinner to improve the axial space factor of the rotor shaft. We are planning to downsize the variable capacitor. Generally, the thickness of the rotor plate at both ends of each section is set to 0.2 to 0.3 mm, and the thickness of the rotor plate on the inside is set to about 0.1 to 0.2 mm, and aluminum is generally often used as the material.

The stator plate facing the rotor plate is approximately semicircular, approximately triangular, or approximately quadrangular in shape, and except for the protruding end that serves as the attachment part, the stator plate is covered with a dielectric film made of plastic film such as polyethylene film on the front and back sides. (There are cases where it is laminated and cases where the stator plate is simply sandwiched between the stator plates.)
At the protruding end of the stator plate, that is, the exposed metal part, stator washers and stator plates are alternately stacked and fixed, and the stator plate pitch is set approximately equal to the rotor plate pitch, and a stator plate group is formed for each section. Form. Then, a variable capacitor was constructed by combining a corresponding rotor plate group and a stator plate group so that the rotor plates and stator plates alternately meshed with each other.

The thickness of the stator plate made of brass etc. is 50 to 100μ, the thickness of the dielectric film is 40 to 50μ,
The air layer (hereinafter referred to as the air gap) existing between the rotor plate and the dielectric film is set to approximately 10μ, and the gap between the rotor plate and stator plate is made as small as possible to increase the capacitance value per unit area. The air gap is made as small as possible to reduce the amount of change in capacitance due to vibration. The main reason why this type of small variable capacitor has this configuration is that there is a very high risk of howling occurring due to plate vibration of the oscillation stage (OSC stage). In other words, in most cases when a small variable capacitor is used in a set, it is installed in the cabinet together with the speaker, so when the output of the speaker is increased, strong vibrations are transmitted to the variable capacitor via the cabinet. Ru. On the other hand, since the rotor plate and stator plate are made of thin materials, they have a resonance point in the audible frequency range, and if the air gap between the rotor plate and stator plate is large, it is effective to reduce the vibration of the rotor and stator plate. The mechanical stress that is a means of achieving this is reduced, and the above-mentioned vibrations of the speaker easily cause resonance and change in capacitance, resulting in howling sound, which generates harsh sounds other than broadcast sound, and reduces the functionality of the set product. For this reason, as mentioned above, air gap is abbreviated.
This is why it is set to an extremely small value of 10μ.

However, as sets such as radio cassettes to which small variable capacitors are attached become more powerful, and vibrations from high-output speakers are transmitted to the variable capacitors, the aforementioned air gap of approximately 10μ still has the disadvantage that it is not a complete countermeasure against howling. It was hot.

To solve this problem, we added an air gap of 10 μm.
If an attempt is made to further tighten the rotor plate, the friction between the rotor plate and the stator plate will increase, resulting in an abnormally large rotational torque, resulting in a situation that is not suitable for practical use. After all, dimensional errors that are unavoidable during manufacturing and assembly processes (for example, slight variations in plate thickness, slight warpage or burrs on plates, variations in plate spacing, rotor plate and stator plate) This is because the rotor plate and stator plate become tightly fitted due to the combination error), and the rotational torque becomes abnormally large.

This invention eliminates the drawbacks of the conventional small variable capacitors, and even if the air gap is compressed to about 5μ, which is about half of the conventional one, the rotational torque does not increase, and it can be mass-produced with productivity equal to or higher than the conventional one. The present invention is intended to provide a small variable capacitor, and the present invention will be explained below with reference to illustrated embodiments.

FIG. 1 shows a rotor plate 1 according to one embodiment of the present invention, and the rotor plate 1 is made of a metal thin plate such as an aluminum thin plate as in the conventional case.
The thickness of the rotor plate on both sides of each section is approximately 0.2 to 0.3 mm, and the thickness of the inner rotor plate is approximately 0.1 to 0.2 mm. The rotor plate 1 has a substantially semicircular shape, and a bulge 1b having a through hole 1a for a metal rotor shaft 2 is formed on the straight side thereof. The outer diameter of the bulging portion 1b is set to be approximately equal to the outer diameter of the metal annular rotor washer 3, and the through hole 1a is formed to be somewhat recessed into the straight side of the rotor plate 1. 1c is an arc-shaped notch provided close to the through hole 1a, communicates with the through hole 1a, and is formed to be concentric with the through hole 1a and located outside the rotor washer 3. .

The rotor plates 1 and the rotor washers 3 are inserted through the rotor shaft 2 in a stacked manner, thereby forming a rotor plate group for each section. The rotor plate 1 and rotor washer 3 are fixed to the rotor shaft 2 by a nut 4 screwed onto the end of the rotor shaft 2 (see FIGS. 2 and 3). The rotor shaft 2 is pivotally supported between a front side plate 5 and a rear side plate 6 that constitute a frame of a small variable capacitor.

On the other hand, the stator plate 7 is also formed from a metal thin plate such as a brass thin plate, and has a thickness of 50 to 100 μm, and is formed into a substantially triangular, semicircular, or quadrangular shape, as in the conventional example described above. . A dielectric film 8 such as a polyethylene film is adhered to the entire surface except for the protruding end 7a (the thickness of the dielectric film 8 is also set to 40 to 50 .mu.m as in the prior art). Then, at the protruding end 7a provided with a hole, the stator plate 7 is alternately laminated with metal stator washers 9, and both 7 and 9 are integrated by means such as laser welding or soldering, and each section is A group of stator plates is formed.

The stator plate group is sandwiched between four pairs of pillars 5a and 6a that protrude integrally from the four corners of the square front plate 5 and rear plate 6, respectively.
It is electrically connected to the terminal rod 10 that is penetrated and press-fitted into the terminals a and 6a. In the assembled state, the rotor plates 1 and stator plates 7 of each section mesh alternately, and the plate spacing (pitch) of each plate group is set so that the air gap G is about 5μ.

In the present invention, since the notch 1c is provided near the holding portion of the rotor plate 1 as described above, the rotor plate 1 is highly flexible, and due to the various dimensional errors mentioned above, the rotor plate 1 Even when the stator plate 7 is strongly engaged, the rotor plate 1 is easily deflected, so the rotational torque does not increase abnormally, and since the air gap G is much smaller than before, howling is reduced. The occurrence of this will also be significantly reduced.

In fact, the conventional rotor plate 21 shown in FIG.
and when the air gap is set to 4μ,
When comparing and experimenting with the case where the rotor plate 1 of the present invention shown in Fig. 1 is used for all the rotor plates of each section and the air gap is set to 4μ, the rotational torque characteristics as shown in Fig. 10 are obtained, In the case of this invention, even if the air gap is small,
It was confirmed that the rotational torque did not increase abnormally and there was no problem in practical use.

In addition, the conventional rotor plate 21 shown in FIG. 9 is used with an air gap of 9μ, and the rotor plate 1 of the present invention shown in FIG. The howling level is compared with the configuration at a rotational speed of the rotor shaft 2 of 25% (the state where the rotor plate 1 is the furthest out of the stator plate 7 is 0%, and the state where the rotor plate 1 is the most inserted is 100%). It was confirmed that the howling level characteristic according to the configuration of the present invention shown in FIG. 12 was significantly improved compared to the conventional howling level (noise level) characteristic shown in FIG. 11.

Note that the rotor plate 1 of the present invention may have various modifications other than the shape shown in FIG. 1, such as a fan-shaped shape communicating with the through hole 1 as shown in FIG. Possible options include a shape cut from a straight side of the plate 1, an arcuate shape separated from the through hole 1a as shown in Figure 7, a configuration with a plurality of notches as shown in Figure 8, or a combination of these. It can be selected as appropriate in consideration of the manufacturability of the mold and the flexibility imparted to the rotor plate.

In addition, in the embodiment described above, all the rotor plates 1 are provided with the notches 1c, but the rotor plates 1 on both sides of each section are not provided with the notches 1c (the outermost rotor plate is bent outward). Even if the notch 1c is provided only in the inner rotor plate 1 (as appropriate hardness is required for tracking adjustment), approximately the same effect can be expected, and the OSC, which has a large effect on howling, can be expected. A notch 1c may be provided in the rotor plate 1 having only stages.
Furthermore, it was confirmed that when the rotor plate 1 is annealed to have a Vickers hardness of Hv (0.5) of 50 or less, the rotor plate 1 becomes even more flexible and contributes to torque reduction.

As mentioned above, according to the present invention, flexibility can be imparted to the rotor plate by providing a notch in the rotor plate. Therefore, even if the air gap is halved compared to the conventional one in order to suppress howling, the rotor plate can be made flexible. It is possible to prevent the frictional force between the rotor plate and the stator plate from increasing due to the bending of the plate, that is, to prevent the rotational torque from increasing. In addition, the rotor plate is highly flexible, so when machining parts,
It also has the advantage of being able to easily combine the rotor plate and stator plate, allowing for some dimensional errors during assembly, and is practical in that it is possible to provide a compact variable capacitor that is highly mass-producible and highly effective in suppressing howling. It has a remarkable effect.

[Brief explanation of the drawing]

Figures 1 to 8 relate to the present invention; Figure 1 is a plan view showing one embodiment of the rotor plate, Figure 2 is an enlarged sectional view of the main part, and Figure 3 is a front view of a simplified small variable capacitor. 4 to 8 are plan views showing different embodiments of the rotor plate, and FIG.
The figure is a plan view showing a conventional rotor plate.
FIG. 0 is a comparison graph of rotational torque characteristics between the conventional configuration and the configuration of the present invention, FIG. 11 is a howling level characteristic diagram of the conventional configuration, and FIG. 12 is a howling level characteristic diagram of the configuration of the present invention. 1...Rotor plate, 1a...Through hole, 1
c...Notch, 2...Rotor shaft, 3...
Rotor washer, 7... stator plate, 8... dielectric film, 9... stator washer, G... air gap.

Claims (1)

[Claims for Utility Model Registration] (1) A plurality of stator plates made of thin metal plates and a plurality of rotor plates made of thin metal plates are alternately engaged, and a plastic film is placed between the stator plates and the rotor plates. In the structure in which a dielectric film is interposed, the rotor plate having a rotor shaft through hole and a conductive annular washer are alternately laminated and attached to the rotor shaft, and a predetermined rotor plate has a rotor plate on the outside of the washer. A small variable capacitor characterized by having notches located in close proximity to each other. (2) The small variable capacitor according to claim (1) of the utility model registration, wherein the notch is formed in an arc shape concentric with the rotor shaft through hole. (3) The small variable capacitor according to claim (2) of the utility model registration, characterized in that the notch communicates with a rotor shaft through hole. (4) The small variable capacitor according to claim (1) of the utility model registration, characterized in that all of the rotor plates of each section of the small variable capacitor are provided with notches. (5) The small variable capacitor according to claim (1) of the utility model registration, characterized in that all rotor plates other than the rotor plates at both ends of each section are provided with notches. (6) The small variable capacitor according to claim (1) of the utility model registration, characterized in that only the rotor plate of the oscillation section is provided with a notch. (7) The scope of claim 1 for registration of a utility model, characterized in that the rotor plate having the notch is annealed to have a Vickers hardness of Hv (0.5) 50 or less.
Small variable capacitor described in (1).