JP2005093761A - Film capacitor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a thin film capacitor in which the variation of characteristics is eliminated and a flattening ratio is large. <P>SOLUTION: The thin film capacitor is a metallized film capacitor obtained by winding a metallized film about the cylindrical winding center of a winding core, and applying a pressure from the outside surface of the wound metallized film toward the inside of the same to flatten the same. The winding core is provided with bent parts at both sides in the radial direction across the widthwise direction of the film so as to permit the bending of the wound film at the bent parts, to achieve a small size, a thin type configuration and the reduction of the man-hours for production. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a film capacitor used for an electric device or the like equipped with an inverter circuit.

  In general, a miniaturized film capacitor is a flat shape that is formed by crushing a cylindrical capacitor element made of a wound film, due to the size of the equipment or power supply used and restrictions such as the mounting area on the printed circuit board. (For example, refer to Patent Document 1).

  8A and 8B show a conventional film capacitor. FIG. 8A is a side view showing the section, FIG. 8B is a plan view seen from the lead wire drawing side, 24 is a capacitor element, and 25 is a capacitor element 24. Metal layers provided on both end faces, 26 is a terminal for drawing out an electrode, 27 is an exterior case, and 28 is a filling resin.

  As shown in FIG. 8, the capacitor element 24 has a flat shape, is built in the case 27, and the periphery thereof is filled in the case with a filling resin 28. Further, a metal layer 25 is provided as an electrode portion at both end portions of the capacitor element, and a terminal 26 for drawing out an electrode is connected to the metal layer 25. This terminal 26 goes out of the case 27 so that it can be connected to the outside.

  FIG. 9 shows a method of forming a capacitor element in a conventional film capacitor, and shows a layout of a metallized film winding device and a pressure roller.

  In FIG. 9, 20 is a core part of a capacitor element, 21 is a metallized film obtained by vapor-depositing a metal film electrode on a dielectric film, 22 is a core part forming pre-winding film, 29 is a capacitor element formed by winding the metallized film 21 , 30 indicates a control roller.

  The operation of the film capacitor configured as described above will be described.

  First, as shown in FIG. 9, the metallized film 21 is wound around the core portion 20 formed by the core portion forming pre-winding film 22 having a cylindrical shape. At this time, from the outer peripheral surface side of the winding capacitor element 29, the prevention roller 30 is disposed so as to press the metallized film 21 in order to prevent the metallized film 21 from being wrinkled. It should be noted that the restraining roller 30 is effective as a measure for preventing wrinkles particularly when the film is thin.

  Further, the capacitor element 29 being wound is cylindrical, and when a metal layer is provided on both end faces of the capacitor element 29, it is crushed by applying pressure from the outside to have a flat shape. In particular, in a capacitor that requires a large capacity, it is necessary to increase the number of capacitor elements arranged in the case, and it is necessary to increase the flatness in order to efficiently fit the case.

  FIG. 10 is a winding situation diagram using a flat core, showing a method of obtaining a flat capacitor element by a method different from the method of crushing a cylindrical capacitor element, 31 is a flat core, 32 Indicates a flat plate core 32 of the winder.

As shown in FIG. 10, there is a method in which a flat core 31 having a flat shape is attached to a flat core 32 of a winder, and the metallized film 21 and the exterior film 23 are wound around.
JP 55-124227 A (FIG. 1)

  However, among the conventional configurations described above, when the film is wound around the flat core, it is difficult to control the tension at the corner of the flat core during the winding operation when the flatness is increased and the thickness is reduced. Therefore, the film stress was large. Also, compared to the case of a cylindrical core, it is not suitable for mass production because the winding speed does not increase, and since it is not possible to use a suppression roller that is effective for thin films, wrinkles are likely to occur, resulting in variations in characteristics. Became big.

  Also, when using a cylindrical core without using a flat core, if the core diameter increases, it will be difficult to crush evenly when crushing into a flat shape, the shape will be distorted, wrinkles will occur, Variations in properties such as non-uniform stress on the film and uneven end faces have been large, which has not been realized.

  In view of the above-described conventional problems, an object of the present invention is to provide a thin film capacitor having a high flatness ratio that eliminates variation in characteristics.

  In order to achieve the above object, the film capacitor of the present invention is formed by winding a metallized film with a cylindrical winding core as a winding center and applying pressure from the outer surface to the inner side of the wound metallized film. In the metal film capacitor, the winding core has a bent portion on both sides in the radial direction over the film width direction, and the bent portion is bent when flattened.

  According to this configuration, variation in characteristics of the capacitor element having a large flatness ratio can be suppressed, and the winding speed can be increased by making the winding core into a round shape, thereby reducing production man-hours.

  As described above, according to the present invention, it is possible to achieve a small and thin shape of the film capacitor and to achieve a great effect that the number of production steps can be reduced.

  Hereinafter, the best mode for carrying out the present invention will be described with reference to FIGS.

(Embodiment 1)
1A and 1B are diagrams showing a capacitor according to the present embodiment, in which FIG. 1A is a side view showing a section, and FIG. 1B is a plan view seen from a lead wire drawing side of the capacitor.

  In FIG. 1, 1 is a core part of a capacitor element, 2 is a bent part provided in the core part 1, 3 is a metallized film in which a metal film electrode is vapor-deposited on the film, and 4 is an exterior film for insulating protection of the capacitor element. Show. Further, 5 is a capacitor element comprising the metallized film 3, the core 1 and the exterior film 4, 6 is a metal layer provided on the end face of the capacitor element 5, 7 is a terminal for drawing out the electrode, and 8 is an exterior in which the capacitor element 5 is accommodated. Case 9 indicates a filled resin. The capacitor element 5 is flattened after being wound in a cylindrical shape.

  Next, FIG. 2 shows a cross-sectional view of the core 1 shown in FIG. 1 before flattening. After the film is wound, pressurization is performed in the direction indicated by the arrow so that the bent portion 2 is bent. So that it can be flattened.

  FIG. 3 shows a layout of the capacitor element and the holding roller during winding of the metallized film. In FIG. 3, reference numeral 10 denotes a capacitor element in the middle of winding the film, 11 denotes a restraining roller, and the metallized film 3 is wound while being restrained by the restraining roller 11 with the core 1 shown in FIG. In addition, by suppressing the metallized film 3 with the roller 11, the wrinkles 15, the slack 16, and the deformation 17 which are the conventional defect examples shown in FIGS. 5B, 5C, and 5D are prevented, and FIG. A normal capacitor element as shown in a) can be formed.

  The film capacitor produced as described above will be described in more detail.

  First, in FIG. 3, as the metallized film 3, a dielectric film for metal deposition is a polypropylene (hereinafter referred to as PP) film, a thickness is 3.5 μm, a width is 80 mm, and a capacitance of a capacitor element to be generated is 300 μF. The material of the core 1 was polyethylene terephthalate (hereinafter referred to as PET), the thickness was 250 μm, and the inner diameter was 80 mm. Further, as shown in FIG. 2, the core portion 1 is provided with a bent portion 2 so that the core portion 1 is easily bent when flattened. In addition, this bending part 2 is provided over the film width direction at two places on both sides in the radial direction. And as shown in FIG. 3, the metallized film 3 is wound around the core part 1 as a winding center. Although not shown in FIG. 3, the end of the metallized film 3 is wound around the outer film 4 shown in FIG. 1 so that the outer film 4 is formed on the outer periphery of the capacitor element 5.

  As shown in FIG. 3, when the film is wound, the core portion 1 has a cylindrical shape with an inner diameter of 80 mm. Therefore, the restraining roller 11 can be disposed, and the restraining roller 11 is placed between the capacitor element and the film. To prevent wrinkling of the film. As described above, in the present embodiment, it is possible to arrange the restraining roller 11 that cannot be achieved by the method of winding a film using a flat core, thereby enabling the production of a highly reliable film. . Furthermore, the film winding speed is faster when the cylindrical core is used than when a conventional flat core is used. As a result of comparison with three types of samples, the time is reduced to 1/5 to 1/6. It turns out that it will be possible.

  Next, a process for flattening the capacitor element will be described. As shown in FIG. 3, in the present embodiment, the capacitor element 10 during film winding has a cylindrical shape, and is flattened before being provided with the metal layer 6 on the end face of the capacitor element. At this time, as shown in FIG. 2, the capacitor element is flattened by applying pressure in the direction of the arrow so that the bent portion 2 becomes the bent portion.

  Thus, by providing the bent portion 2 in advance and making it bend easily, it can be flattened uniformly without unevenness of the end face, and a normal element as shown in FIG. The wrinkles 15, slack 16, and deformation 17 shown in (b), (c), and (d), which are generated when a round core is used, can be prevented.

  The reason why the material of the core part is PET is that the mechanical strength is strong, so that the thickness of the core part can be reduced, and the size can be further reduced as required.

  Further, as shown in FIG. 1B, the flattened capacitor element is formed with metal layers 6 at both ends and heat-treated in a vacuum at 120 ° C., and then a terminal 7 for drawing an electrode to the metal layer 6 is provided. As a result, the capacitor element 5 is formed. Further, the capacitor element 5 is inserted into the outer case 8 and filled with the filling resin 9 to obtain a metallized film capacitor. The filling resin was an epoxy resin.

  As described above, according to the present embodiment, the bent portion 2 disposed on the core portion 1 can be uniformly flattened, and the winding core has a round shape, thereby suppressing variations in capacitor characteristics and winding. Speed can be increased and production man-hours can be reduced.

  In addition, as shown in FIG. 2, the core part 11 in the present embodiment is cylindrical and has a shape in which two portions on both sides in the radial direction are recessed inward, and the recessed part is a bent part. The shape is not limited to this, and other shapes may be used. This will be described.

  First, the 2nd Example of the core part used for this Embodiment is demonstrated using FIG. FIG. 5 shows a second embodiment of the core portion, and 12 is a bent portion provided at both ends in the radial direction of the cylindrical core portion, and the thickness is reduced. That is, in the second embodiment of the core portion, the bent portions 12 provided on both sides in the radial direction are thin over the film width direction, and flattening is performed by applying pressure in the direction of the arrow in the figure. When it does, it will bend easily in the thinned part. That is, according to the embodiment of the second core portion, the flattening can be performed uniformly by the bent portion 12 disposed on the core portion 1. Further, since the winding core has a cylindrical shape at the time of film winding, variations in capacitor characteristics can be suppressed, the winding speed can be increased, and the number of production steps can be reduced.

  Similarly, third and fourth embodiments of the core part will be described with reference to FIGS.

  FIG. 6 shows an embodiment of the third core portion, wherein 13 is a bent portion provided at both ends in the radial direction of the cylindrical core portion, and the bent portion breaks the core portion. ing. As described above, the winding core part 1 is provided by being broken in a linear shape across the film width direction on both sides in the radial direction, and when flattened by applying pressure, Since the strength of the rupture portion is weak, it is easily bent at the weakened portion.

  FIG. 7 shows an embodiment of the fourth core part, in which two semi-cylindrical core parts are butted to form a cylindrical core part. The butt portion formed at both ends in the radial direction of the portion is a bent portion 14. Then, when flattening by applying pressure, the butted portion, that is, the bent portion 14 is weakened. Therefore, the bent portion 14 is easily bent.

  The bent portions 13 and 14 as shown in the third and fourth embodiments of the core described above can be uniformly flattened, and when winding the film, the core is cylindrical. Therefore, variations in capacitor characteristics can be suppressed, the winding speed can be increased, and the number of production steps can be reduced.

  In the present embodiment, the material of the core portion is PET, but PP may be used. By using PP, flattening is performed during heat treatment in vacuum at 120 ° C. after forming the metal layer 6. It is possible to increase the adhesive strength between the wound core portions, further suppress variations, and improve the characteristics.

  In particular, according to the conventional method, when the core diameter is set to 20 mm or more, problems occur, and it is difficult to obtain a highly reliable capacitor when it is desired to increase the core diameter and increase the flatness. However, according to the present embodiment, it is effective to obtain a flat capacitor having a high flatness ratio with a core diameter of 20 mm or more.

  Furthermore, the structure by using a pre-winding film as a winding core, and making it bend | fold after forming it by adhesion | attachment, such as heat sealing, is also possible.

  The film capacitor of the present invention is small and can achieve a thin shape, can reduce the number of production steps, and is useful for a power supply circuit and the like that are strongly demanded for a small and thin shape.

(A) Side view showing a cross section of the first embodiment of the film capacitor of the present invention (b) Plan view of the film capacitor according to the first embodiment of the present invention as viewed from the lead wire drawing side of the capacitor The figure which shows the Example of the core which has a bending part Film capacitor holding roller layout (A) A diagram showing a normal flattened capacitor element (b) A diagram showing a first example showing a fault of a flattened capacitor element (c) A second example showing a fault of a flattened capacitor element FIG. 4D is a diagram showing a third example showing a defect of the flattened capacitor element. The figure which shows the 2nd Example of the core which has a bending part. The figure which shows the 3rd Example of the core which has a bending part. The figure which shows the 4th Example of the winding core which has a bending part. (A) Side view showing a cross section in the first embodiment of the conventional film capacitor (b) Plan view seen from the lead wire drawing side of the capacitor in the first embodiment of the conventional film capacitor Conventional film capacitor holding roller layout Winding situation diagram of flat film core of conventional film capacitor

Explanation of symbols

1 Core part 2, 12, 13, 14 Bending part 3 Metallized film

Claims (7)

A metal film capacitor is formed by winding a metallized film with a cylindrical core part as a winding center, and flattening by applying pressure from the outer side of the wound metallized film to the inside, and the core part is A metallized film capacitor having a bent portion over the film width direction at both end portions in the radial direction so that the bent portion is bent when flattened. The metallized film capacitor according to claim 1, wherein the core portion has bent portions that are recessed inwardly at both ends in the radial direction of the cylinder. The metallized film capacitor according to claim 1, wherein the winding core has bent portions with reduced thickness at both ends in the radial direction of the cylinder. The metallized film capacitor according to claim 1, wherein the core portion has broken bent portions at both end portions in the radial direction of the cylinder. The metalized film capacitor according to claim 1, wherein the winding core portion is formed by abutting two semicircular cylindrical shapes into a cylindrical shape, and the butted surfaces at both end portions in the radial direction of the cylinder are bent portions. The metallized film capacitor according to claim 1, wherein the core is made of polyethylene terephthalate. The metallized film capacitor according to claim 1, wherein the core is made of polypropylene.

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