JPS58153321A - Condenser - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a capacitor, and particularly to a capacitor formed by combining an electrolytic capacitor and a film capacitor.

In general, electrolytic capacitors are excellent in that they can have a large capacitance, but their impedance shows a high value at frequencies of several hundred KHz or more, making them impractical for use in high frequency ranges.

In recent years, the switching frequency of switching power supplies has increased to several hundred K.
Electrolytic capacitors used in this type of power supply, which are set in a high frequency range of Hz or higher, are required to have low impedance characteristics not only in low frequency ranges but also in high frequency ranges.

By the way, although it is difficult to obtain a high capacitance like an electrolytic capacitor, a film capacitor has high frequency characteristics that cannot be obtained with an electrolytic capacitor.

An object of the present invention is to provide a capacitor that has a large capacitance and is suitable for high frequency bands by forming a composite of an electrolytic capacitor and a film capacitor with common electrodes, and taking advantage of the features of both.

This invention provides an anode-side electrode having a dielectric oxide film and a synthetic resin film separately formed on its surface, a cathode-side electrode disposed opposite to this electrode, and a dielectric oxide film of the anode-side electrode. It is characterized by comprising a separator paper interposed between a surface portion on which a film is formed and a surface portion of a cathode side electrode facing this surface portion.

Embodiments of the invention will be described in detail with reference to the drawings. 1 and 2 show an embodiment of the present invention, and FIG. 1 is an exploded perspective view of the capacitor element. In FIG. J2 and FIG. 2, which are enlarged sectional views showing a part of the electrode structure, this capacitor element 2 has strip-shaped electrode foils 4.6 formed of aluminum or the like on the anode side electrode and the cathode side electrode. The electrode foils 4.6 on the anode side and the cathode side are tightly wound together with a separator paper 8 interposed between one side thereof, and the inside thereof is impregnated with an electrolytic solution.

Electrode tabs 1o and 12 are individually electrically connected to each electrode foil 4.6 by fixing means such as welding in order to connect to an external lead-out terminal. Note that this capacitor element 2 is packaged with a highly airtight exterior case made of metal such as aluminum or insulating synthetic resin.

In this capacitor element 2, the surface of the electrode foil 4 on the anode side is made into a corrugated surface by etching, and then a dielectric oxide film 14 is formed on the negative surface by chemical conversion, and a synthetic resin film is formed on the other surface. 0 where 1G is formed
The synthetic resin film 16 is formed on the surface of the electrode foil 4 made of etched synthetic resin such as polyethylene or polypropylene to a thickness of 1 μm using thin film forming techniques such as vacuum evaporation, ultraviolet polymerization, electron beam irradiation polymerization, glow discharge polymerization, and gamma ray irradiation curing.
The electrode foil 4 is formed to have a thickness of about 100 mL, and its surface area is expanded as the surface of the electrode foil 4 becomes corrugated.

The dielectric oxidation degree of the electrode foil 4 formed in this way is 11!1
The electrode foil 6 on the cathode side faces the surface of the electrode foil 4 with a separator paper 8 interposed therebetween, while the synthetic tree bark ll11 of the electrode foil 4
Electrode foils 6 on the cathode side are directly opposed to the surface portion 6, and an electrolytic solution 18 is interposed between each electrode foil 4.6. That is, in this embodiment, the electrode foil 4 on the anode side and the electrode foil 6 on the cathode side
An electrolytic capacitor element is formed between the two surfaces, and a plastic film capacitor element is formed between the other surfaces. These capacitor elements are electrode foil 4.6
They are formed in such a way that they are alternately stacked in the form shown in FIG. 2.

The capacitor element 2 thus formed has a configuration in which an electrolytic capacitor 20a and a film capacitor 20b are connected in parallel, as shown in the equivalent circuit shown in FIG. , 22b'IJ(
It becomes what is formed.

With this configuration, the impedance-frequency characteristics are a combination of the characteristics of the electrolytic capacitor 20a and the characteristics of the film capacitor 20b. In other words, this capacitor provides low impedance characteristics in an extremely wide frequency band from low frequencies to high frequencies, and can reduce high frequency loss, so it is possible to reduce switching frequencies of several hundred KHz.
It passes through the smoothing capacitor of the switching power supply set above.

Furthermore, since the synthetic resin film 16 is formed on the etched surface of the electrode foil 4 using the thin film forming technique described above, it is extremely thin, for example, about 1 μm in thickness, and is formed along the etched surface. is expanded according to the expansion magnification of the electrode foil 4, resulting in a large capacitance that cannot be obtained with conventional film capacitors.
6 side. That is, the capacitance on this film capacitor side is about ten to several tens of percent of the total capacitance of the capacitor element 2.

FIG. 4 shows another embodiment of the invention.

That is, in the above embodiment, the dielectric oxidation degree 11114 and the synthetic bark ll116 were individually formed on the electrode foil 4 on the anode side, but in this embodiment, the dielectric oxide film 1 was formed on the entire surface of the electrode foil 4.
4, and a synthetic resin skin 11116 is selectively laminated on the upper surface of this dielectric oxide skin 11114. In this way, if a no-coat part 19 such as a pinhole shown by a broken line occurs in the synthetic resin film 16 laminated on the upper surface of the dielectric trial skin [1114], this non-coat part 19 There is a dielectric experience skin inside the
1114 prevents an electrical short circuit with the electrode foil 6 on the cathode side, and furthermore, the electrolytic solution impregnated into this non-coated portion 19 penetrates, so that it cannot function as a normal electrolytic capacitor element. can.

Further, FIG. 5 shows a case where the capacitor of the present invention is applied to a flat plate capacitor. The capacitor element 24 of this embodiment has a dielectric coating W/A 14 and a synthetic resin coating 11116 formed on the electrode plate 26 on the anode side, similar to the electrode foil 4 on the anode side of the previous embodiment, and the electrode plate 28 on the cathode side. are bent and arranged so as to face the front and back surfaces of this electrode plate 26. Then, the separator paper 30 is inserted between the electrode plates 26 and 28 on the side where the electrolytic capacitor element is to be formed.

Even with this configuration, the same composite structure as in the previous embodiment is obtained as shown in FIG. 3, so that similar characteristics can be obtained. In this embodiment, similar characteristics can be obtained even if the arrangement of the electrode plate 26 on the anode side and the electrode plate 28 on the cathode side is reversed.

Next, the experimental results of this invention'b will be explained with reference to FIG.

In the experiment, we used a capacitor of the form shown in Figure 5 formed to a rated voltage of 50 V and a rated capacitance of 220 μF, and for comparison, a normal electrolytic capacitor formed to the same rated voltage and capacitance as shown in Fig. 5. was used as an experimental capacitor.

I! p, the electrode foil 26 on the anode side of the former is -1 x 90-
dielectric oxide film on the - side and 1μ on the other side.
In order to form a synthetic resin film with a thickness of , and to form the electrode foil 24 on the anode side of the latter to have the same capacitance as the former, the size is set to -1 x Seki-1, and a dielectric film is applied on both sides. This is formed by forming an oxidized film on the body. FIG. 6 shows the frequency-impedance characteristics measured for each capacitor, where curve A is the characteristic of the capacitor according to the present invention and curve B is the characteristic of a normal electrolytic capacitor.

As is clear from this characteristic curve, the capacitor according to the present invention exhibits characteristics similar to ordinary electrolytic capacitors in the low frequency range, while the low impedance range is 5 MHz.
z, and low impedance characteristics can be obtained over a wider range than with ordinary electrolytic capacitors. That is, it can be seen that the capacitor of the present invention has a large capacitance and low impedance characteristics, and as a result, it is suitable for a switching power supply where the switching frequency is set to several hundred K11z or more.

In addition, in the above embodiment, separator paper was inserted only between the electrode foils on the side that forms the electrolytic capacitor, but even if separator paper is further inserted between the electrode foils on the side that forms the film capacitor, the effect of the present invention will be impaired. It's not a thing.

In addition, in each example, the dielectric oxide film and synthetic resin film forming each capacitor were separated by the front and back surfaces of the anode side electrode, but one surface of the anode side electrode was partitioned and each film was selectively placed side by side. You can get the same effect with 0. For example,
The surface portion of the electrode foil on the anode side may be divided into certain ranges, and the surface portion of each section may be made into a dielectric oxide film surface or a synthetic resin film surface.

As explained above, according to the present invention, it is possible to combine the characteristics of an electrolytic capacitor and a film capacitor, and to construct a capacitor having a large capacitance and low impedance characteristics in a high frequency range. It can be effectively used in switching power supplies with high switching frequencies.

[Brief explanation of the drawing]

FIG. 1 is a perspective view showing an embodiment of the capacitor of the present invention;
Figure 2 is an enlarged sectional view showing the main parts of this capacitor, Figure 3
Figure 4 is an explanatory diagram showing the equivalent circuit, Figure 4 is a sectional view showing another embodiment of the invention, Figure 5 is a perspective view showing an embodiment in which the invention is applied to a plate capacitor, and Figure 6 is an impedance diagram. - It is a characteristic explanatory diagram showing frequency characteristics. 2.24... Capacitor element, 4... Electrode foil as anode side electrode, 6... Electrode foil as cathode side electrode, 8
．． 30... Separator paper, 14... Dielectric oxide film, 26... Electrode plate as an anode side electrode, 28... Electrode plate as a cathode side electrode. Figure 1/ Figure 2 Figure 3 Figure 4

Claims (1)

[Scope of Claims] (11) An anode-side electrode in which a dielectric oxide film and a synthetic resin film are separately formed on the surface portion, a cathode-side electrode in which power is distributed opposite to this electrode, and the anode-side electrode. A capacitor characterized by comprising a separator paper interposed between a surface portion on which a dielectric oxide film is formed and a surface portion of a cathode side electrode opposite to this surface portion. (2) The anode side electrode is The capacitor according to claim 1, characterized in that a dielectric oxide film is formed on the entire surface, and the synthetic resin film is formed on a part of the surface of the dielectric oxide film. (3) The anode The capacitor according to claim 1 or 2, characterized in that the side electrode has a dielectric oxide film formed on one surface and a synthetic resin film formed on the other surface. 3. The capacitor according to claim 1, 2 or 3, wherein the front and back surfaces thereof are divided into predetermined areas and a dielectric oxide film or a synthetic resin film is formed thereon.