JPH045253B2 - - Google Patents

Description

[Detailed description of the invention] Industrial applications The present invention relates to high voltage capacitors.

Conventional Structure and its Problems Conventionally, the structure of this type of capacitor is as shown in FIGS. 1, 2, and 3. A metal layer 2 formed by metal foil or vapor deposition on both sides of the dielectric film 1 shown in FIG.
The required interval 3 is maintained. These metal layers 2 are arranged as individually insulated electrodes, and each metal layer 2 forms a part opposing an electrode formed by two adjacent metal layers 4 on the other surface of the dielectric film 1. It is located in A dielectric film 1 and a dielectric film 5 having metal layers 2 and electrodes 4 on both sides are stacked and wound into a roll to form a capacitor.

At this time, as shown in FIG. 2, the electrodes are drawn out by using a metal foil 6 on at least one of the electrodes that partially oppose each other at the beginning and end of the winding, and attaching a lead wire to the surface of the metal foil 6. 7 and 8 are welded.

In this type of capacitor constructed as described above, the metal layers 2 and 4 on each side of the dielectric film 1 are arranged on both sides of the dielectric film 1, and the metal layers 2 and 4 on each side are arranged on both sides of the dielectric film 1, respectively. Capacitors C1, C2, C3 shown in FIG.
...It is equivalent to Cn connected in series. Each capacitor C1, C2, C3...Cn is applied with V1, V2, V3...Vn, which is the voltage Vs applied between the lead wires 7 and 8 divided, so its withstand voltage is increased. Theoretically, it is possible to increase the voltage resistance of the capacitor. However, in the capacitor described above, the lead wires 7 and 8 welded to the surface of the metal foil are wound around the metal foil surface in order to draw out the electrodes, so there is a problem in that winding workability is poor and productivity is low.

In addition, as a characteristic problem caused by the winding of the lead wires 7 and 8, the withstand voltage level of the dielectric film 1 near the welded parts of the lead wires at the beginning and end of winding decreases, and the actual withstand voltage of the capacitor is lower than the theoretical one. The pressure resistance is inferior to that of the standard. This means that when the lead wire and dielectric film are wrapped together, the dielectric film receives mechanical stress, and when the dielectric film overlaps the lead wire,
This is because, especially when the number of windings is small, the dielectric film is curved and distorted by the wire diameter of the lead wire, and the electric field is concentrated in this portion, which lowers the withstand voltage level. One way to prevent this drop in withstand voltage level is to insert a dielectric film for withstand voltage compensation at the lead wire connection position, but this method is not productive and is not effective because it does not interfere with other capacitances that are connected in series. There are disadvantages such as it is not common because the balance is disrupted.

Furthermore, since the welded part between the metal foil and the lead wire has a certain resistance value, when high voltage is repeatedly applied, the welded part generates heat due to the resistance.
There was also the risk that thermal deterioration of the dielectric film would occur and the withstand voltage would drop. As a result, there was a problem in that the reliability as a capacitor decreased.

OBJECTS OF THE INVENTION It is an object of the present invention to eliminate the above-mentioned drawbacks, prevent a decrease in breakdown voltage of a capacitor having a high breakdown voltage structure, increase productivity, and provide a highly reliable capacitor.

Structure of the Invention In order to achieve the above object, the capacitor of the present invention has electrodes made of a plurality of metal layers individually insulated in the length direction arranged on both sides of a dielectric film, and each electrode is connected to the opposite side. The dielectric film is arranged so as to overlap two electrodes made of adjacent metal layers, and this dielectric film and another dielectric film are wound in a layered manner, and metal foil is used for the electrodes at the beginning and end of the winding, The end of the metal foil at the beginning of the winding is placed outside the end of the dielectric film, and the metal foil at the end of the winding is wound around the outermost circumference to form a capacitor, and these two metal foils are used as an electrode lead-out. did.

As described above, since the electrode lead-out is made of metal foil, there is no need to wind up the electrode lead wire as in the conventional case, and the winding operation of the capacitor element is extremely easy. Further, the mechanical stress to which the dielectric film is subjected is small, and the dielectric film is free from distortion due to partial curvature and no electric field concentration occurs over the entire length of the dielectric film from the beginning of winding to the end of winding of the capacitor. Furthermore, since the connection from the metal foil to the lead wire is reliably made, there is a feature that there is little heat generation even when high voltage is repeatedly applied, and there is no thermal deterioration of the film.

DESCRIPTION OF EMBODIMENTS An embodiment of the present invention will be described with reference to FIGS. 4, 5, and 6.

In FIG. 4, a metal layer 2 1 made of a dielectric film and a metal layer 4 evaporated are formed as electrodes on both sides with a required spacing 3 maintained.
5 is a dielectric film. These structures are the same as the conventional example shown in FIG. The feature of the present invention is that metal foils 6 and 6' are used, and when the dielectric film 1 and the dielectric film 5 are wound to form a capacitor, they face each other at the beginning and end of the winding. It is used as one of the electrodes forming the portion 9 and the opposing portion 10.

Also, as shown in FIG. 5, at the beginning of the winding of the metal foil 6, one of the ends in the width direction of the metal foil 6 protrudes outward from the ends in the width direction from the dielectric films 1 and 5. Similarly, as shown in FIG. 6, the metal foil 6' is wound in several layers around the outermost periphery of the capacitor element at the end of the winding. Two metal foils, the metal foil 6 that is wound and protrudes from the end face of the capacitor element, and the metal foil 6' that is wound around the outermost layer, are used as electrode extensions of the capacitor. ...Cn As mentioned above, since the metal foil 6 and the metal foil 6' are used as electrode leads of the capacitor, productivity is improved compared to the conventional structure in which the lead wire is welded to the surface of the metal foil and wrapped around it. has improved significantly. Furthermore, compared to the conventional example, the dielectric film 1 is
Since the mechanical stress generated in the dielectric film 2 is reduced and the dielectric film is not bent at the beginning and end of winding, there is no fear of deterioration in breakdown voltage due to electric field concentration. Furthermore, thermal deterioration of the dielectric film due to heat generated at the welded portion of the lead wire does not occur.

FIG. 7 shows the results of a voltage boost breakdown test of capacitor A having the structure of the present invention and capacitor B having a conventional lead wire wound around the electrode.

Figure 8 shows the time course of the survival rate (number of breakdowns/number of tests) in a test in which a voltage of 1.4 times the constant O-P was repeatedly applied to capacitor A of the present invention and capacitor B of conventional structure in an 85°C atmosphere. It shows.

In FIGS. 7 and 8, it is demonstrated that the withstand voltage effect obtained by the electrode lead-out structure of the present invention is good.

Note that the above example shows a case where vapor-deposited metal is used as the electrode layer of each capacitor element, but
The dielectric layer can also be deposited on a dielectric film or made of a metal foil.

Effects of the Invention As described above, in the capacitor of the present invention, a plurality of individually insulated electrodes are arranged on both sides of the dielectric film in the length direction, and each electrode is overlapped with two adjacent electrodes facing each other. It has a high withstand voltage structure in which the metal foil is placed on top of another dielectric film and wound together with another dielectric film, and furthermore, metal foil is used for the electrodes at the beginning and end of the winding, and the metal foil at the beginning of winding is placed outside the end of the dielectric film. Then, the last metal foil was wound around the outermost circumference, and these two metal foils were used as electrode extensions. Therefore, it is possible to prevent a decrease in the withstand voltage level, which was a drawback of conventional capacitors with a high withstand voltage structure, and to improve productivity.
We have been able to provide a high voltage film capacitor that is inexpensive and highly reliable.

Although the above explanation shows the case where only one dielectric film 1 is disposed, it is also possible to arrange multiple dielectric films one on top of the other. can be further improved.

[Brief explanation of drawings]

Fig. 1 is an explanatory diagram showing the configuration of a conventional capacitor, Fig. 2 is an enlarged perspective view with a part of the conventional capacitor opened, Fig. 3 is its equivalent circuit, and Fig. 4 shows the structure of the capacitor of the present invention. Explanatory drawings, FIG. 5 is an enlarged perspective view showing the capacitor of the present invention in the middle of winding, FIG. 6 is a perspective view showing the end of winding, and FIG. FIG. 8 is a graph showing the level of destruction of capacitors, and is a graph showing changes over time in the survival rate of capacitors of the present invention and conventional capacitors as a result of repeated high voltage application tests. 1, 5... Dielectric film, 2, 4... Electrode consisting of a metal layer, 6, 6'... Metal foil.

Claims (1)

[Claims] 1 Electrodes consisting of a plurality of individually insulated metal layers are arranged on both sides of the dielectric film in the length direction,
Each electrode is arranged so as to overlap two electrodes made of mutually adjacent metal layers on the facing side,
This dielectric film and another dielectric film are overlapped and wound, and metal foil is used for the electrodes at the beginning and end of the winding, so that the end of the metal foil at the beginning of winding is closer to the end of the dielectric film. A capacitor characterized in that the capacitor is constructed by winding the last metal foil placed on the outside around the outermost periphery, and these two metal foils are used as electrode extensions.