JPS6130272Y2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to electromagnetic shielding of electrolytic capacitors.

Generally, an electrolytic capacitor is manufactured by connecting a lead plate 1 to an anode electrode foil and a cathode electrode foil made of aluminum or the like by caulking or the like, as shown in FIG. 1, and then winding them through a separator such as electrolytic paper. A capacitor element 3 is formed by fixing the end of the winding with an element fixing tape 2. Next, after impregnating the element with an electrolytic solution, the lead plate 1 which can be led out from the capacitor element 3 is connected to the external terminal 4 which has been installed through the sealing plate 5 by riveting, embedding, etc., and is inserted into the case 6. , the element fixing material 7 is injected and the open end of the case 6 is wrapped and sealed.

When a high-frequency current is passed through such an electrolytic capacitor, if the case is a metal case such as aluminum, the magnetic flux generated by winding the aluminum electrode of the capacitor element 3 will cause an extremely large amount of magnetic flux, although not as much as with magnetic metal. It was found that less loop current occurs at the bottom of the cylindrical metal case.
It is generally known that these magnetic fluxes and loop currents have a negative effect on acoustics from an acoustic technology standpoint, and in order to reduce these magnetic fluxes and loop currents, the bottom of the cylindrical metal case has been removed. , a structure in which a cylindrical metal pipe is used with the bottom made of rubber baking or resin, or a resin case is used instead of a metal case.

However, although these methods reduce the loop current, the magnetic flux exits to the outside, so it still has an adverse effect on the mounting chassis and components surrounding the electrolytic capacitor after it is attached to the board. Further, since the influence of magnetic flux from the outside is also exerted on the capacitor, it has not been possible to substantially reduce the influence of magnetic flux.

The present invention eliminates these drawbacks and seeks to provide an electrolytic capacitor in which the influence of magnetic flux is significantly reduced without significantly changing the working method.

The present invention will be described in further detail below.

When non-magnetic objects are placed in a magnetic flux, they become magnetized by the magnetic flux, but at this time, depending on the object, the direction of the minute magnetic flux generated by magnetization may be different from the original magnetic flux. It is known that there are cases where the direction is the same as that of , and cases where it is the opposite direction. Depending on these directions, the former is called a paramagnetic material, and the latter is called a diamagnetic material.

Conventionally, the aluminum case used as a capacitor case has a paramagnetic material, so as shown in FIG. A minute magnetic flux 10 is generated from the aluminum 9. However, as shown in B, if the capacitor case is made of diamagnetic material 11 instead of aluminum 9, a minute magnetic flux 12 will still be generated in the same way as shown in A, but the direction of this magnetic flux will be The direction is opposite to that shown. In other words, it can be said that the loop currents generated at the bottom of the capacitor case are in opposite directions in A and B.

In view of the above points, the present inventors repeated various experiments and combined two types of materials: a paramagnetic material with a positive value of relative magnetic susceptibility and a diamagnetic material with a negative value of relative magnetic susceptibility. It has been found that a capacitor in which a capacitor element is housed in a case significantly improves sound quality when used in the power supply circuit of audio equipment.

First, as metals for paramagnetic and diamagnetic materials, aluminum, a paramagnetic material with a positive relative magnetic susceptibility, and silver, a diamagnetic material with a negative relative magnetic susceptibility, were bonded together to form capacitors. I created a case and measured the magnetic flux when energized by applying a single input signal. The results are shown in FIG. 3 in comparison with a conventional product constructed using an aluminum case. 3A shows a conventional product constructed using an aluminum case, and FIG. 3B shows a case using a case made of aluminum laminated with silver.

From the above results, it seems that magnetic flux is generated by bonding the paramagnetic and diamagnetic metals together so that their loop currents cancel each other out, conversely suppressing the magnetic flux that exits to the outside.

This invention was devised based on the above results.
This shields magnetic flux from inside the capacitor and also shields magnetic flux from the outside.

That is, the present invention uses ground carbon powder as a coloring material for the conventionally manufactured resin case for black capacitors, and focuses on the fact that the ground carbon powder is a paramagnetic material. After mixing crushed carbon powder and the same amount of ground diamagnetic powder, the mixture is added to resin to form a case. The addition ratio of the mixture to this resin is 2.0~
About 40% by weight is good; if it is less than 2% by weight, it will not be very effective, and if it exceeds 40% by weight, the moldability of the case will be very poor.

FIG. 4 shows an embodiment of the electrolytic capacitor of the present invention, in which 13 is a lead terminal led out from the capacitor element 3, 14 is a sealing body, and 15 is a mixed powder of the above-mentioned diamagnetic material and paramagnetic material. The resin case contains and molds ground carbon powder as a paramagnetic material.
Silver powder is used as a diamagnetic substance, and 10% by weight of each is mixed into polypropylene resin. 16 is a filling resin.

By using the resin case according to the present invention described above in place of the conventional case made of aluminum or the like, the same effects as the experimental results shown in Figure 3B can be obtained, and the process of manufacturing the conventional resin case electrolytic capacitor can be achieved. Since this electrolytic capacitor can be manufactured without any modification, when used in the power supply circuit of audio equipment, the sound quality is significantly improved compared to conventional products.

The diamagnetic substances to be mixed include:
There are many examples such as silver, lead, copper, etc., and the examples are not limited to those described above.

As described above, the electrolytic capacitor of the present invention not only shields the magnetic flux generated from the inside of the capacitor, but also shields the influence from the outside, and has great practical value.

[Brief explanation of drawings]

Figure 1 is a sectional view of a conventional electrolytic capacitor, Figure 2 is a cross-sectional view of a conventional electrolytic capacitor.
FIG. 3 is an explanatory diagram of magnetic flux, FIG. 3 is an induced voltage-time characteristic diagram observing the influence of magnetic flux, and FIG. 4 is a sectional view of an embodiment of the electrolytic capacitor of the present invention. 3: Capacitor element, 13: Lead terminal, 1
4: Sealing body, 15: Resin case, 16: Filling resin.

Claims (1)

[Scope of utility model registration request] An electrolytic capacitor in which a capacitor element is housed in a molded resin case containing mixed powder of ground diamagnetic material and ground paramagnetic material.