JPS6120127B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to improvements in electrolytic capacitors used in audio equipment and the like.

In recent years, electronic components such as capacitors used in audio systems have been designed primarily with an emphasis on electrical characteristics.However, as audio technology develops, not only electrical characteristics but also sound quality in audio systems are being designed. It is well known that emphasis has been placed on evaluation. Especially in electrolytic capacitors, due to differences in parts, structure, etc.
It is an electronic component with a lot of room for improvement because it has a large effect on the sound quality of audio equipment.

In a conventional electrolytic capacitor, as shown in Fig. 1, an external lead terminal 1 is connected to an anode foil and a cathode foil by crimping or the like, and then the capacitor element 2 is formed by winding the terminals with electrolytic paper interposed therebetween. . Next, the element 2 was impregnated with an electrolytic solution, a sealing member 3 made of rubber or the like was attached, and the element 2 was inserted into a case 4 made of aluminum or the like, and the opening of the case 4 was sealed.

When a high-frequency current is passed through such an electrolytic capacitor, generally in the case of a metal case such as aluminum, the loop current is extremely small due to the magnetic flux caused by winding the aluminum electrode of the capacitor element, although it is not as strong as with magnetic metal. It was found that this occurs at the bottom of a cylindrical metal capacitor case. However, when it comes to sound quality in audio technology, it is well known that loop current is a major cause of sound quality distortion.
In order to eliminate this loop current, the bottom part of the cylindrical metal capacitor case has been removed and a cylindrical metal pipe has been used to form the bottom part with rubber baking or resin, and a resin case has been used instead of the metal case. I have not yet reached the point where I am fully satisfied.

The present invention eliminates the above-mentioned drawbacks and provides an electrolytic capacitor whose loop current can be easily reduced or eliminated without significantly changing the method of operation.

That is, in the present invention, when graphite is ground, carbon-
It is known that the breaking of carbon bonds occurs, causing a large change in magnetic susceptibility and inducing paramagnetism. In particular, various types of ground carbon can be treated by heat treatment at 400 to 700°C. Taking advantage of the properties of carbon that cause large differences in magnetic flux, and the fact that carbon is highly conductive among non-metals, we have impregnated the capacitor element of an electrolytic capacitor housed in a conventional resin case with paste. After applying the rated voltage to the electrodes of the element and measuring the potential difference between the top lead extraction side and the bottom side of the element, it was found that the potential on the bottom side was high at the outer periphery and was several mV to
A potential difference of several tens of millivolts is generated, and the material for general resin cases contains a small amount of carbon black, about 0.4 to 1.6% by weight, as a coloring agent, but molding is possible even with an increased content of carbon black. As a result of various experiments, it was discovered that strain rate characteristics can be significantly improved by adding an increased amount of ground carbon such as carbon black to the resin used to mold the case.

That is, the present invention applies to case molding resin materials 1 such as polypropylene, nylon (trade name of polyamide-based synthetic polymer resin manufactured by DuPont), and Noryl (trade name of aromatic polyether resin manufactured by General Electric). 2.0 to 40% fine powder of ground carbon made of polycrystalline graphite, acetylene black, carbon black, activated carbon, etc.
% by weight is molded to form a resin case, and the capacitor element is housed and sealed in the resin case.

FIG. 2 shows an embodiment of the electrolytic capacitor of the present invention, in which 5 is an external lead terminal, 6 is a capacitor element, 7 is the above-mentioned resin case, 8 is an elastic sealing body,
Reference numeral 9 denotes a filled resin, and 10 denotes an explosion-proof mechanism section in which a thin wall portion, a groove, etc. are provided in the resin case 7. The thin wall portion and the groove may be provided not only on the bottom but also on the side surface.

Therefore, an electrolytic capacitor in which a capacitor element is housed in a case formed in this way and sealed is
The magnetic flux perpendicular to the bottom surface of the case generated by the capacitor element is prevented by the paramagnetic properties of the ground carbon on the bottom surface of the case, and its path is bent instead of perpendicularly permeating it, which is conventionally caused by the magnetic flux. This reduces and eliminates the effect on other parts caused by mounting the board, as well as the loop current generated in the board. This is presumed to be due to the carbon acting as an electrostatic shield, and the potential difference on the surface of the capacitor element decreases or disappears due to the conductivity of the carbon.

The reason why the content of ground carbon is limited to 2.0 to 40% by weight is that if the content of ground carbon is less than 2.0%, the specific resistance of the resin case is too high and it becomes an insulator, which causes the electrostatic charge described above. The effect of the shield cannot be obtained,
If the amount of ground carbon exceeds 40% by weight, the resin will not flow into the details during molding of the resin case and will become brittle. The airtightness is poor, and the electrolyte oozes out or absorbs moisture.
The specific resistance of the resin case is small and it becomes conductive.
This is because the effect of electrostatic shielding cannot be obtained.

Next, the strain rate characteristic diagram of the electrolytic capacitor of the present invention (rated at 50 WV, 1000 μF) constructed using a resin case containing ground carbon as described above and the conventional electrolytic capacitor (rated at 50 WV, 1000 μF) is shown in Figure 3.
In the figure, A is a product of the present invention and B is a conventional product. As is clear from the figure, the electrolytic capacitor of the present invention is
It can be seen that the distortion rate at 30KHz has been significantly improved, and there is a significant effect. Furthermore, when the electrolytic capacitor of the present invention was installed in a circuit such as a power supply of an audio system and listened to, it was proved that the three-dimensional effect was improved and the sound quality was superior compared to conventional electrolytic capacitors.

As mentioned above, the present invention is an electrolytic capacitor that is housed in a resin case containing ground carbon such as polycrystalline graphite, acetylene black, carbon black, and activated carbon. As it disappears, the bass becomes quieter and comes out,
In addition, the distortion rate characteristics in the high frequency range are greatly improved, and the third harmonic is significantly reduced, so that when used in audio systems, various audio transmission systems, etc., it produces a remarkable effect of high fidelity.

[Brief explanation of the drawing]

Figure 1 is a sectional view of a conventional electrolytic capacitor, Figure 2 is a cross-sectional view of a conventional electrolytic capacitor.
The figure is a sectional view of an embodiment of the electrolytic capacitor of the present invention, and FIG. 3 is a distortion rate characteristic diagram of the electrolytic capacitor, where A is a product of the present invention and B is a conventional product. 6: Capacitor element, 7: Resin case.

Claims (1)

[Claims] 1 Polypropylene, polyamide-based synthetic polymer,
For every 1 part of case molding resin material such as aromatic polyether, 2.0 parts of ground carbon such as polycrystalline graphite, acetylene black, carbon black, activated carbon, etc.
An electrolytic capacitor characterized by a capacitor element housed in a resin case made by adding up to 40% more weight.