JPH0746667B2 - Composite film capacitor - Google Patents

Description

TECHNICAL FIELD The present invention relates to a high voltage composite film capacitor.

(Prior Art) Conventionally, in a circuit that uses a plurality of capacitors having a withstand voltage of several KV or more, for example, in a voltage doubler rectifier circuit that generates a high voltage, prepare a required number of individual capacitors and solder them one by one. It is assembled by connecting to the circuit by the method, and there is a problem in improving productivity by eliminating the number of parts. Therefore, conventionally, a composite capacitor having a plurality of capacitor elements in one capacitor element has been devised. FIG. 5 shows the structure of a conventional composite capacitor. In the figure, 11 is a dielectric film, and metal foil 12 is used as an electrode, and a lead wire is directly attached to each metal foil.
It consisted of 13 connected.

FIG. 6 is an equivalent circuit diagram of the same, and FIG. 7 is an external view of the same.

FIG. 8 shows another conventional example. Dielectric film as electrode
Evaporated metal 14 formed on 11 is used, and lead wire 13
Was formed by applying a metallikon 15 to the end face of the capacitor after winding and connecting to the metallikon 15. FIG. 9 is an equivalent circuit diagram of the same, and FIG. 10 is an external view of the same.

(Problems to be Solved by the Invention) The conventional configuration has the following problems.

First, in the conventional example using a metal foil as an electrode, since there is no self-recovery function, if the dielectric film contains a defect, complete destruction occurs at a low voltage, lack of reliability, and a large shape is disadvantageous. there were.

Next, in another conventional example using a vapor-deposited metal as an electrode, since the electrode is drawn out by a metallikon, it is difficult to secure an insulation withstand voltage between two capacitor elements, which is a problem particularly when increasing the withstand voltage. .

Further, in order to increase the withstand voltage in the structures shown in the above two conventional examples, a method of increasing the thickness of the dielectric film is used, but the relationship between the dielectric thickness d and the withstand voltage V is , V =
It is given by Kd ⁿ (n = 0.7 to 0.1, K is a constant), and it is necessary to lower the voltage per unit thickness (μm) of the dielectric film,
In addition to the problem that the shape is large, there is a drawback that if the dielectric film is too thick, such as several + μm or more, it becomes difficult to wind it, and a composite capacitor having a withstand voltage of several KV or more has not been put to practical use.

The object of the present invention is to eliminate the drawbacks of the prior art, to have high reliability,
It is to provide a small high voltage composite film capacitor.

(Means for Solving the Problems) The composite film capacitor of the present invention is a metallized film in which a plurality of vapor-deposited electrodes insulated from each other are formed in a lengthwise direction of a continuous dielectric film. A capacitor obtained by winding the electrodes of a film so as to overlap and oppose two vapor deposition electrodes adjacent to each other on which the other metallized film is formed, wherein the ends of the start and end of the metallized film are wound. A metal foil electrode is used instead of the vapor deposition electrode for the partial electrode and an arbitrary intermediate electrode, and lead wires are connected to the metal foil electrode and led out.

(Function) With the above configuration, the inside of each capacitor of the composite capacitor becomes a circuit in which a plurality of capacitor elements are connected in series, and the applied voltage is divided by the capacitor elements, so that the resistance per unit thickness of the dielectric film is increased. High withstand voltage can be achieved without lowering the voltage, and the high reliability of the vapor-deposited metal electrode and the ease of lead wire extraction of the metal foil electrode can both be achieved. Since it is formed of a thin evaporated metal electrode, it is possible to suppress an increase in the diameter of the capacitor.

(Embodiment) An embodiment of the present invention will be described with reference to FIGS. 1 to 4.

FIG. 1 is a sectional view for explaining the structure of the composite film capacitor of the present invention. In the figure, a dielectric film 1 on the strip, for example, a polyester film is provided, and a metal such as aluminum is formed on the dielectric film 1 by vapor deposition while keeping a predetermined interval X in the lengthwise direction to form a vapor deposited metal electrode 2. In addition, the metal foil electrode 3 for leading out the lead wire
Is configured by disposing a metal foil such as aluminum on the dielectric film 3 instead of the vapor deposition electrode 2. The insulating band forming the interval X and the non-deposited metal portion Y overlapping with the metal foil electrode 3 apply a voltage to a portion of the vapor-deposited metal that is continuous in the lengthwise direction to scatter a portion of the vapor-deposited metal. Can be formed by Each of the electrodes 2 and 3 is overlapped so that the electrode of one metallized film overlaps and opposes two electrodes adjacent to each other formed on the other metalized film, and is wound in a roll shape in the length direction. Then, the lead wire 4 is led out from each metal foil electrode 3 to form a composite film capacitor. With this configuration, as in the equivalent circuit shown in FIG. 2, the capacitor between the lead wires is internally a series circuit of a plurality of capacitor elements C ₁ to C ₄ or C ₅ to C ₈ and has a high withstand voltage. A composite film capacitor can be obtained.

FIG. 3 is an external view of a composite film capacitor of the present invention wound in a roll shape, and FIG. 4 is a plan view of a metal film in which a plurality of electrodes insulated in the length direction are formed in an island shape.

In this embodiment, two dielectric films are used, but a plurality of films may be used by superposing them, and electrodes may be arranged on both outer surfaces of the superposed films. In addition, in the present embodiment, the metal foil electrodes for taking out the lead wires serving as the common terminals are arranged at symmetrical positions,
The required breakdown voltage can be arranged at any position depending on the electrostatic capacity.

(Effect of the Invention) According to the present invention, when the same rated product is compared with the conventional example,
The size can be reduced by about 20% to 50% by volume,
A compact and highly reliable high-voltage composite film capacitor can be put into practical use, and there is an effect that productivity can be improved by eliminating the number of parts in the used circuit.

[Brief description of drawings]

FIG. 1 is a sectional view of a composite film capacitor according to an embodiment of the present invention, FIG. 2 is an equivalent circuit diagram thereof, FIG. 3 is an external view thereof, FIG. 4 is a plan view thereof, and FIG. 6 is a sectional view of the film capacitor, FIG. 6 is an equivalent circuit diagram thereof, FIG. 7 is an external view thereof, FIG. 8 is a sectional view of another conventional composite film capacitor, FIG. 9 is an equivalent circuit diagram thereof, and FIG. Is an external view of the same. 1 ... Dielectric film, 2 ... Evaporated metal electrode, 3 ... Metal foil electrode, 4 ... Lead wire.

Claims (1)

[Claims] 1. A metallized film in which a plurality of vapor-deposited electrodes insulated from each other are formed in the length direction of a continuous dielectric film, and an electrode of one metallized film is formed in the other metallized film. In a capacitor obtained by winding two vapor deposition electrodes adjacent to each other so as to overlap and oppose each other, an end electrode at a winding start and a winding end of the metallized film and an arbitrary intermediate electrode are provided on the vapor deposition electrode. Instead, a metal foil electrode is used, and a lead wire is connected to each of the metal foil electrodes and led out.