JPS596522A - Metallized film 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 metallized film capacitor constructed by winding a metalized film in which metal electrodes are formed on the surface of a dielectric film by vapor deposition.

Conventionally, in metallized film capacitors, Fig. 1a
, b, a metal electrode 2 is formed by vapor deposition on one or both sides of a dielectric film 1 such as a polypropylene film, a polyester film, or a polycarbonate film.
By forming an insulating groove part (usually called a margin part, hereinafter referred to as a margin part) of about 0.6 MM to 6 MM at the end of the dielectric film 1 in the width direction, a metal insulating film is formed. 4
When obtaining a capacitor using such a metallized film 4, two metallized films 4 are overlapped and wound as shown in FIG. 2, and the wound metallized film 40 is
Zn, Sn, Cu on both end faces.

The electrode lead portion 6 is formed by spraying a metal material such as PB,
Either connect the lead wire 6 to the electrode extension part by welding or the like to form a capacitor element, or as shown in FIG. The capacitor elements are stacked, and the electrodes are made into a bow, similar to the previously described wound type capacitor.

By the way, if such wound type and laminated type capacitors are analyzed and evaluated in detail in terms of productivity, capacitor characteristics, etc., each type has advantages and disadvantages.

In particular, the major difference in characteristics is that multilayer capacitors have a structure in which multiple small capacitance capacitors are connected in parallel, so even if a part of the metallized film breaks down due to some abnormality during use, Only one capacitor element loses its function, with little effect on other capacitor elements, resulting in only a slight reduction in capacitance. This means that it can be said to be an extremely safe capacitor with a safety function.

On the other hand, wound type capacitors are currently mainstream because they can be easily manufactured using conventional general equipment, but if some abnormality occurs during use, some parts of the metallized film When a breakdown phenomenon occurs, the capacitance change due to the breakdown phenomenon is only a decrease proportional to the reduced area of the electrode of the metallized film, so it is negligible at the initial stage. Since the round-shaped capacitor is a single capacitor, the damage gradually progresses without stopping, with one part of the broken part serving as a core, and eventually leads to smoke and ignition. Therefore, in this wound type capacitor, sufficient safety cannot be ensured unless some kind of safety device is added.

In view of the current situation, the present inventors have proceeded with the development of a capacitor that has both the high productivity of a wound type capacitor and the high safety of a multilayer capacitor. As a result, as shown in FIG. 4, the electrodes 2 are arranged in a plurality of rectangular island shapes in the length direction of the metallized film 4, separately from the margin portions 3 provided at the ends in the width direction of the metallized film 4. A margin part 7 connected to the margin part 3 is provided so as to be separated into two parts,
If two such metallized films 4 are stacked and wound to form a capacitor element, it can be manufactured in the same way as a wound type capacitor, and the electrode structure is the same as a laminated type. Due to this structure, even if a destructive phenomenon occurs in a part of the electrode 2, it will not spread to the whole, and accidents such as smoke and ignition can be prevented. In other words, they discovered that they could be equipped with safety functions. In FIG. 1, reference numeral 6 indicates an electrode extension portion formed on the end face of the capacitor element, and 6 indicates a lead wire.

However, if a metallized film capacitor having such a structure is required to have a withstand voltage of 400 VAC or more, the thickness of the dielectric film 1 must be made extremely thick. However, it has many drawbacks, such as being difficult to manufacture and having a large size. Therefore, in response to high safety requirements in such high voltage fields, conventional safety devices have been used, but this method also
It has many drawbacks like the former method, such as being extremely complex and difficult to manufacture, resulting in high prices, and because the safety device is mechanical, it is slow and does not provide sufficient safety. Ta.

゛The present invention was discovered as a result of further development of the capacitor having the above-described structure, and provides a metallized film capacitor that has a high withstand voltage, high productivity, and has a highly reliable safety function. It is something. Hereinafter, the content of the present invention will be explained in detail.

In the present invention, with the aim of achieving high withstand voltage and highly reliable safety functions, as a result of various experiments and studies, as shown in Figure 6, one metal The inventors have found that it is sufficient to provide the intermediate margin portion 8 in the width direction of the film 4. This intermediate margin portion 8 cuts off conductivity in the width direction of the electrode 2 and maintains insulation. Note that the other metal film 4 has margin portions 3 provided only at both ends, and serves as a common electrode. Further, in the case of a double-sided metallized film, margin parts 7 and 8 may be provided on the electrodes on one side to separate them.

A capacitor with such an electrode structure is considered to have two capacitor elements C1 and C2 connected in series and a plurality of them connected in parallel under the equality constraint, as shown in FIG. Since the voltage applied to C1 and C2 is usually half of the voltage between the terminals since C1=02, compared to the capacitor having the structure shown in Fig. 4, if the thickness of the dielectric film 1 is the same, , the withstand voltage is doubled.

FIG. 7 shows the change in the current flowing through the capacitor over time in a test in which a voltage three times the rated voltage of the capacitor was continuously applied to the capacitor of the present invention in an atmosphere at room temperature to 10° C.

Compared to conventional capacitors whose capacitance gradually decreases over time and requires a long time to completely stop functioning as a capacitor, the capacitor of the present invention has a capacitance that gradually decreases over time and requires a long time to completely stop functioning as a capacitor. It can be seen that it becomes completely open over time and stops functioning as a capacitor. This phenomenon is caused by the fact that in the circuit shown in Figure 6, if C1 now breaks down and its capacity decreases, the voltage applied to C1 is vC1, vC1=C2/
This is because (C1+02)×v increases, further promoting the destruction of C1 and accelerating the decrease in capacity.As a result, a state where the fuse becomes completely open in a short period of time is realized like a general fuse. Therefore, it is possible to obtain an extremely safe capacitor that has little influence on other devices and circuits.

In addition, in contrast to the conventional capacitor, which requires a long period of time to operate the safety function while destruction is progressing due to the application of high voltage, there is a risk of fire and smoke due to self-heating of the capacitor. Since the function of the capacitor stops in a short period of time, there is no need to take into account the effect of self-heating during destruction, and it is therefore possible to significantly improve the limit voltage at which safety can be ensured. The situation is shown in FIG.

The safety rate in Figure 8 is (the number of capacitors in which the capacitors are completely open without any abnormality such as smoke or ignition)/(the number of capacitors that are completely open during the test) at each applied voltage in an atmosphere from room temperature to 100'C. The total number of capacitors used) is XIQO.

As described above, the metallized film capacitor of the present invention has a high withstand voltage and can ensure safety of 100%, that is, can add a highly reliable safety function, and also Conventional manufacturing equipment for wound type capacitors can be used as is, and an excellent effect can be obtained in that it can be carried out at low cost.

[Brief explanation of drawings]

Figures 1a and b are perspective views showing examples of general metallized film, Figure 2 is a perspective view showing the main parts of a general rolled metallized film capacitor, and Figure 3 is a perspective view of a general laminated film capacitor. FIG. 4 is a perspective view showing the main parts of a conventional metallized film capacitor equipped with a safety function. FIG. 5 is a perspective view showing the main parts of a metallized film capacitor according to an embodiment of the present invention. 6 is an equivalent circuit diagram of the metallized film capacitor of the present invention, and FIGS. 7 and 8 are characteristic diagrams for explaining the effects of the metallized film capacitor of the present invention, respectively. be. 1... Dielectric film, 2... Electrode,
3. End: Margin part, 4: Metallized film, 8: Intermediate margin part. Name of agent: Patent attorney Toshio Nakao and 1 other person 1st
Figure 2 Figure 4 Figure 5 Figure 6 @ Figure 7 Time (W), Figure 8

Claims (1)

[Claims] A capacitor element is constructed by winding a metallized film on which stain electrodes are formed by vapor deposition on the surface of a dielectric film, and the electrodes are separated into a plurality of islands in the width direction and length direction of the metallized film. An insulating groove is provided so that the
A metallized film capacitor characterized by having a circuit configuration in which a plurality of series circuits of capacitor elements are connected in parallel.