GB2322013A

GB2322013A - Flyback transformer

Info

Publication number: GB2322013A
Application number: GB9801951A
Authority: GB
Inventors: Takeshi Nomura; Futoshi Matsumoto; Hisao Yamashita; Tadao Yubine; Shinji Okada
Original assignee: Matsushita Electric Industrial Co Ltd
Current assignee: Panasonic Holdings Corp
Priority date: 1997-01-31
Filing date: 1998-01-29
Publication date: 1998-08-12
Anticipated expiration: 2018-01-29
Also published as: GB9801951D0; GB2322013B

Abstract

A flyback transformer comprises a high voltage output arrangement 22p and a high voltage capacitor which include connection portions 11p, 22pa that are arranged such that the said output arrangement 22p and capacitor may be interconnected by pushing the connection portions 11p, 22pa together. The capacitor may have an electrically conductive rubber connection portion 11p and the output arrangement may have a needle shaped connection portion 22pa. The output arrangement 22p may be a single metal piece with a number of connection portions 22pa, 22pb. Also disclosed is a flyback transformer comprising a high voltage output unit and a fixing plate in which the fixing plate includes clamping portions which clamp onto a portion of the high voltage output unit (see figs.9 - 13). A method of manufacturing such a transformer is also disclosed. The above arrangements allow reliable automated assembly of a flyback transformer without the need for soldering or the need to check for bad connections or joints that may leak during epoxy impregnation.

Description

FLYRACK TRANSFORMER The invention relates to a flyback transformer (hereinafter, often abbreviated as "FBT") which is used in, for example, a display device using a cathode ray tube for a color television receiver or a computer terminal device Figs. 6 to 8 shows an FBT of the prior art. Fig. 6 is a view showing a portion of a prior art flyback transformer where a high-voltage product is connected, Fig. 7 is a view showing a connecting portion between a high-voltage capacitor of the flyback transformer and a protection resistor, and Fig.

8 is a view illustrating the configuration of the flyback transformer.

In the figures, ip designates a ferrite core, 2p designates a primary winding, 3p designates a primary winding bobbin, 4p designates a secondary winding, 5p designates a secondary winding bobbin, 6p designates rectifying devices which rectify an output pulse, 7p designates a high-voltage capacitor, 8p designates a part fixing plate to which the rectifying devices 6p, the high-voltage capacitor 7p, and the like are to be fixed, 9p designates an epoxy resin which is an insulating material, lOp designates an outer case, lip designates electrically conductive rubber which is used for connecting a high-voltage conductor 16p, 12p designates a first protection resistor in which one terminal is a sharpened, 13p designates a second protection resistor, and 14p designates an insulating tube. These components constitute the FBT body.

The reference numeral 35p designates a high-voltage product in which a terminal 17p having a sharp tip end is pressingly in contact with one end of the high-voltage conductor 16p and an anode cap and an anode connecting metal piece (both are not shown) are attached to the other end. An insulating rubber cap 19p, a first fixing sleeve 20p, and a second fixing sleeve 21p are attached to a middle portion.

When the high-voltage product 35p is inserted into the insulating tube 14p of the FBT body, the terminal 17p at the tip end of the high-voltage product 35p is inserted into the conductive rubber llp inserted into the insulating tube 14p, and an engagement portion 20pa of the first fixing sleeve 20p is engaged with an inner end engagement portion lOpa of the high-voltage terminal portion of the outer case lOp, thereby forming a configuration which can hold the high-voltage product 35p and the FBT body.

Electrical connections in the FBT body are mainly realized by the conductive rubber and soldering or crimping.

For example, in the connecting portion between the FBT body and the high-voltage conductor 16p, ds shown in Fig. 6, a resistor lead 12pa of the high-voltage output unit of the FBT is connected to the terminal 17p of the high-voltage product 35p via the conductive rubber lip. As shown in Fig. 7, connections at the terminals of the secondary winding 4p and the rectifying devices 6p, between the second protection resistor 13p of the high-voltage capacitor 7p and the first protection resistor 12p, and of the high-voltage capacitor 7p are realized by soldering 15p. In other words, the connections between the parts attached to the part fixing plate 8p, such as the highvoltage capacitor 7p and the rectifying devices 6p are completed before the FBT body is attached to the outer case lOp.

The part fixing plate 8p in which the connections have been completed in this way is disposed on the coil body formed by fitting the primary and secondary winding bobbins 3p and 5p to each other, and the coil body is inserted into the outer case lOp of the FBT, thereby configuring the FBT body. In order to insulate the high voltage portion of the FBT body, the FBT body is impregnated with the epoxy resin 9p which is an insulating material and the resin is then cured.

In such an FBT, the electrical connection of the conductive rubber lip and the first protection resistor 12p in the connection for the high-voltage conductor 16p is conducted by using the sharp end of the lead 12pa of the first protection resistor which is bent into a U-like shape, or accomplished by inserting the sharp end into the conductive rubber lip. Since tip end 12pa of the first protection resistor 12p is bent into a U-like shape and its position cannot be fixed, the tip end is inferior in strength and positionally uncertain.

The electrical connections of the high-voltage capacitor 7p and the rectifying devices 6p or the terminals of the first and second protection resistors 12p and 13p are realized by soldering. Such soldering has problems in reliability such as a short circuit caused by "solder TEMPURA" or adhesion of solder to another place, and also in that unstableness of the soldering work causes automatization to be hardly conducted.

In order to impregnate the coil body with the epoxy resin 9p and cure the resin, the coil body is inserted into the outer case lOp. For the connections which require soldering, the electrical and mechanical connections must be completed before the insertion of the coil body into the outer case lOp.

This produces a problem in that the number of production steps is increased.

Further, the invention relates to a flyback transformer which is used in a high-voltage circuit of a television receiver or the like.

Conventionally, a flyback transformer (hereinafter, often abbreviated as "FBT") of this kind has a configuration shown in Fig. 14 or 15. In Figs. 14 and 15, for the sake of description, the transformer is shown in partial section.

Referring to Fig. 14, the FBT comprises: an outer case 3q; a coil unit body 7q including a primary coil bobbin lq on which a primary winding is wound, and a secondary coil bobbin 2q on which a secondary winding is wound in plural layers; and a part fixing plate 4q having rectifying devices 25q which are respectively connected between the layers, and a resistor 26q.

One end of the resistor 26q is connected to the rectifying device 25q which is on the highest voltage side, and the other end is formed as a lead wire 26qa having a tip end which is bent into a U-like shape. A hollow insulating tube 5q in which a through hole 5qd is formed at a part of a middle portion is inserted into a high-voltage output unit 3qa of the outer case 3q. Electrically conductive rubber 6q is inserted into the end of the insulating tube 5q which is on the side of the interior of the FBT.

When the coil unit body 7q in which the part fixing plate 4q is disposed is attached to the outer case 3q, the tip end of the resistor 26q attached to the part fixing plate 4q, i.e., the lead wire 26qa which is bent into a U-like shape is inserted into the conductive rubber 6q which is inserted into the insulating tube 5q attached to the outer case 3q.

On the other hand, an anode cap 9q and an anode connecting metal piece 10q are attached to one end of a highvoltage cable 8q, and a terminal metal piece llq having an arrow-shaped tip end is attached to the other end. An insulating rubber cap 12q, a fixing sleeve 13q, and another fixing sleeve 14q are fitted onto a middle portion of the high voltage cable 8q, with the result that these components configure a high-voltage product 15q as a whole.

When the high-voltage product 15q is inserted into the insulating tube 5q of the outer case 3q, the fixing sleeve 14q engages with the engagement portion formed between the highvoltage output unit 3qa and the insulating tube 5q, thereby allowing the high-voltage product 15q to be held on the outer case 3q. At the same time, the arrow-shaped terminal metal piece 11q at the tip end of the high-voltage product 15q is pressingly inserted into the conductive rubber 6q inserted into the insulating tube 5q, through the hole 5qd of the insulating tube 5q. As a result, the coil unit body 7q and the rectifying devices 25q are connected to the high-voltage product 15q via the conductive rubber 6q.

Fig. 15 shows another configuration of the prior art, and Figs. 16A to 16C show a clamping portion of the FBT. The coil unit body 7q, the part fixing plate 4q, the outer case 3q, and the insulating tube 5q are configured in the same manner as those shown in Fig. 14.

A connecting metal piece 21q which serves as the highvoltage output unit and which has a V-shaped portion 21qa at the tip end is attached to the part fixing plate 4q. The part fixing plate 4q has two clamping portions 4qa which respectively have substantially L-like and inverted L-like section shapes. The clamping portions are inserted into the insulating tube 5q to clamp the connecting metal piece 21q.

The contacting portions of the clamping portions 4qa which are in contact with the connecting metal piece 2lq (the areas between the L-like and inverted L-like portions) are flat, and the portion of the connecting metal piece 21q which is clamped is flat.

The part fixing plate 4q to which the connecting metal piece 21q is attached is disposed in the coil unit body 7q, and the coil unit body 7q is inserted into the outer case 3q into which the insulating tube 5q has been inserted. As a result, under the state where the connecting metal piece 21q is housed in the gap defined by the two clamping portions 4qa of the part fixing plate 4q, the connecting metal piece is inserted into the inner end Sqa of the insulating tube 5q, and the outer case 3q and the coil unit body 7q are fixed together. In order to prevent resin leakage from occurring, the internal dimension C of the inner end 5qa of the insulating tube 5q, and the external dimension D (see Fig. 16A) of the clamping portions 4qa of the part fixing plate 4q are set so as to attain a degree of interference of C < D.

On the other hand, in the high-voltage product 15q, the anode cap 9q and the anode connecting metal piece 10q are attached to one end of the high-voltage cable 8q the core of which is a solid wire, and the insulating cover at the other end is peeled off so that only the core wire 8qa is projected.

An insulating rubber cap 12q is fixed onto a middle portion of the high-voltage cable 8q so as to configure the high-voltage product 15q.

When the high-voltage product 15q is inserted into the outer case 3q, the core wire 8qa of the high-voltage cable 8q is inserted into the V-shaped portion 2lqa of the connecting metal piece 21q which is inserted into the insulating tube 5q.

As a result, the high-voltage product 15q and the outer case 3q are fixed together, and the coil unit body 7q and the rectifying devices 25q are connected to the high-voltage product 15q via the connecting metal piece 21q. Since the connecting metal piece 21q has the V-shaped portion 21qa at the tip end, the core wire 8qa of the high-voltage cable 8q which is once inserted into the portion is hardly disengaged therefrom.

The configurations of the prior art have the following problems: (1) parts are large in number, the material cost is high, and increased manpower is required; (2) the U-like shape of the lead of the resistor cannot be maintained during the subsequent production steps, and hence the lead is unstably inserted into the conductive rubber 6q; and (3) when the connecting metal piece 21q is to be housed in the gap between the clamping portions 4qa of the part fixing plate 4q (the gap between the L-like and inverted L-like portions), the connecting metal piece 21q may be unsurely housed in the gap between the clamping portions 4qa or the dimensional accuracy is impaired, and, when a vacuum casting process using an insulating epoxy resin is conducted after the FBT is assembled, a gap is formed between the connecting metal piece 21q and the clamping portions 4qa and the resin may leak from the gap.

Specifically, in the configuration such as shown in Fig. 14, the high-voltage product 15q has a large number of parts, or the fixing sleeve 13q, the fixing sleeve 14q, and the arrow-shaped terminal llq, and intensive manpower is required for assembling these parts. In the coil unit body 7q, manpower for inserting the conductive rubber 6q into the insulating tube, or installation cost for automatizing the insertion is largely increased.

The resistor lead which is bent into a U-like shape is projected from the end of the resistor by about 15 mm, and there is no member to which the lead is to be fixed. After the resistor is attached to the part fixing plate 4q, therefore, the resistor lead may be moved by transferring operation, vibration, or the like during subsequent production steps, with the result that, when the resistor lead is to be inserted into the conductive rubber 6q, the position of the resistor lead is unstable and hence the insertion may be impossible. Even when the insertion is conducted, the lead may be inserted between the conductive rubber 6q and the inner wall of the insulating tube 5q. In such a case, when an epoxy resin is injected, the epoxy resin may enter between - the resistor lead and the conductive rubber 6q, thereby causing a conduction failure.

In the configuration of Fig. 15, when the connecting metal piece 21q is to be housed in the gap between the clamping portions 4qa of the part fixing plate 4q, the connecting metal piece 21q is inserted between the clamping portions 4qa which are separated into two members, in a step of automatically inserting parts such as the rectifying device 25q and the resistor 26q. Thereafter, the clamping portions 4qa are inserted into the insulating tube 5q, with the result that the structure in which the connecting metal piece 21q is housed between the clamping portions 4qa is accomplished. During a period after the connecting metal piece 21q serving as the high-voltage output unit is inserted into the part fixing plate 4q and before the FBT is assembled, therefore, the connecting metal piece 21q may be caused not to be housed in the gap between the clamping portions 4qa of the part fixing plate 4q or the clamping portions 4qa may be shifted from each other by transportation among assembling stations, vibration, or dispersion in the automatic inserting process (see Fig. 16C).

When a vacuum casting process using an insulating epoxy resin is conducted, the resin may leak from the gap between the clamping portions 4qa.

Under the state in which the FBT is assembled and has not yet been subjected to impregnation of an epoxy resin, it is very difficult to check whether the connecting metal piece 21q is surely inserted or not. Furthermore, also the work of checking whether the resin leaks or not is very difficult to do. After the automatic insertion of the connecting metal piece 21q, therefore, the position of the connecting metal piece 21q must be again checked. A leak of the resin from the portion where the connecting metal piece is housed produces a failure that the core wire 8qa of the high-voltage product 15q cannot be inserted into the connecting metal piece.

It is an object of the invention to provide a flyback transformer which can be efficiently produced by simplified production steps.

According to the first aspect of the present invention, a flyback transformer of the first aspect comprises: an outer case; a coil unit including at least a primary winding and a secondary winding comprising plural layers; rectifying devices which are respectively connected between the layers of the secondary winding; and a high-voltage output unit for the secondary winding, wherein the flyback transformer further comprises a part fixing plate in which the high-voltage output unit has a connecting portion, the connecting portion being connected to a connecting portion of the high-voltage capacitor which is separately formed, by moving the connecting portion of the high-voltage capacitor to approach the connecting portion of the high-voltage output unit.

Preferably the connecting portion disposed in the high-voltage output unit has a needle-like shape and the connecting portion of the high-voltage capacitor is made of electrically conductive rubber.

Preferably the connecting portion disposed in the high-voltage output unit is a single metal piece including: a first connecting portion which is connected to the connecting portion of the high-voltage capacitor which is separately formed, by moving the connecting portion of the high-voltage capacitor to approach the first connecting portion; and a second connecting portion through which a high voltage is output to an outside.

Preferably, the flyback transformer further comprises: a high voltage capacitor fixing plate comprising the high-voltage capacitor and the connecting portion of the high-voltage capacitor, and the outer case comprises: a part fixing plate holding unit which directly or indirectly fixes a part fixing plate; and a positioning unit which positions at least a part of the high-voltage capacitor fixing plate.

According to a second aspect of this invention a method of producing a flyback transformer comprises the steps of: a first step of inserting a part fixing plate in which connecting means is formed in a high-voltage output unit, into an outer case, the connecting means comprising: rectifying devices which are respectively connected between layers of a secondary winding; a high-voltage output unit for the secondary winding; and connecting means in the high-voltage output unit, the connecting means being connected to a connecting portion of a high-voltage capacitor which is separately formed, by moving the connecting portion of the high-voltage capacitor to approach the connecting means; and a second step of inserting a high-voltage capacitor fixing plate comprising a high-voltage capacitor and the connecting portion of the high-voltage capacitor, into the outer case, thereby connecting the connecting means disposed on the part fixing plate, to the connecting portion of the high-voltage capacitor.

According to a third aspect of the present invention, a part fixing plate for a flyback transformer comprises: rectifying devices which are respectively connected between layers of a secondary winding; a high-voltage output unit for the secondary winding; and a connecting portion disposed in the high-voltage output unit, the connecting portion being connected to a connecting portion of a high-voltage capacitor which is separately formed, by moving the connecting portion of the high-voltage capacitor to approach the connecting portion disposed in the high-voltage output unit.

Preferably in a part fixing plate for a flyback transformer, the connecting portion disposed in the high-voltage output unit has a needle-like shape.

Preferably, in a part fixing plate for a flyback transformer, the connecting portion disposed in the high-voltage output unit is a single metal piece including: a first connecting portion which is connected to the connecting portion of the high voltage capacitor which is separately formed, by moving the connecting portion of the high-voltage capacitor to approach the first connecting portion; and a second connecting portion through which a high voltage is output to an outside.

According to another aspect of this invention a flyback transformer comprises: an outer case; a coil unit including at least a primary winding and a secondary winding having plural layers of the secondary winding; a part fixing plate having rectifying devices which are respectively connected between the layers, and a high-voltage output unit for the secondary winding; and an insulating tube in which the high-voltage output unit is connected to a high-voltage cable, the part fixing plate further has two clamping portions which are inserted into the insulating tube to clamp the high-voltage output unit, the clamping portions having a semicylindrical section shape, a face of each of the clamping portions which is in contact with the high-voltage output unit is flat, a clamped portion of the high-voltage output unit is flat, and the clamping portions are approximately equal in width to the clamped portion of the high-voltage output unit, in an at least partial manner.

Preferably a diameter of a tip end portion of each of the clamping portions is smaller than a diameter of a body portion of the clamping portion.

Preferably a portion of the high-voltage output unit with which the high-voltage cable is engaged is projected from the clamping portions.

Particular embodiments in accordance with this invention will now be described with reference to the accompanying drawings in which: Fig. 1 is a view illustrating the vicinity of a connecting metal piece of the flyback transformer of an embodiment of the invention.

Fig. 2 is a view illustrating the configuration of the flyback transformer.

Fig. 3A is a side view showing the connecting metal piece of the flyback transformer; and Fig. 3B is a bottom view of the connecting metal piece.

Fig. 4A is a plan view of the vicinity of a capacitor fixing plate of the flyback transformer; Fig. 4B is a side view of the capacitor fixing plate; and Fig. 4C is a bottom view of the capacitor fixing plate.

Fig. 5 is a view showing a positioning unit of an outer case of the flyback transformer.

Fig. 6 is a view showing a portion of a prior art flyback transformer where a high-voltage product is connected.

Fig. 7 is a view showing a connecting portion between a high-voltage capacitor of the flyback transformer and a protection resistor.

Fig. 8 is a view illustrating the configuration of the flyback transformer.

B Fig. 9 is a view illustrating the configuration of a flyback transformer of an embodiment of the invention.

Fig. 10 is a view showing clamping portions of a part fixing plate of the flyback transformer.

Fig. 11 is a view showing a connecting metal piece of a high-voltage output unit.

Fig. 12A is a section view of the connecting metal piece of the high-voltage output unit; Fig. 12B is a section view of the clamping portions of the part fixing plate; and Fig. 12C is a section view showing a state in which the connecting metal piece of the high-voltage output unit is combined with the clamping portions of the part fixing plate.

Fig. 13 is a view illustrating main portions of the flyback transformer in a connected state.

Fig. 14 is a view illustrating the configuration of a flyback transformer of the prior art.

Fig. 15 is a view illustrating the configuration of another flyback transformer of the prior art.

Fig. 16A is a sectional view illustrating the clamped portion of a part fixing plate of a flyback transformer; Fig.

16B is a sectional view illustrating the clamped portion and the connecting metal piece of the high-voltage output unit; and Fig. 16C is a sectional view illustrating the clamped portions which are shifted.

According to the configuration, in the first flyback transformer of the invention, the connecting portion of the high-voltage capacitor which is separately formed can be connected to the part fixing plate by moving the connecting portion of the high-voltage capacitor to approach the part fixing plate. Therefore, it is not required to conduct cumbersome connecting works, particularly, a soldering work, so that the production efficiency can be enhanced.

In the second flyback transformer of the invention, since the connecting portion disposed in the high-voltage output unit has a needle-like shape and the connecting portion of the capacitor is made of electrically conductive rubber, the connecting work can be conducted easily and surely.

In the third flyback transformer of the invention, since the connecting portion disposed in the high-voltage output unit is a single metal piece including the first and second connecting portions, parts can be shared. This contributes an improved efficiency of the connecting work.

The fourth flyback transformer of the invention comprises the capacitor fixing plate comprising the capacitor and the connecting portion of the capacitor, and the outer case comprises: the part fixing plate holding unit which directly or indirectly fixes the part fixing plate; and the positioning unit which positions at least a part of the capacitor fixing plate. Therefore, the capacitor fixing plate can be held by the part fixing plate and the positioning unit which are inserted into the outer case, and the outer case, the part fixing plate, and the capacitor fixing plate are held by each other, whereby a stable state can be maintained.

The method of producing a flyback transformer of the invention comprises the steps of: the first step of inserting the part fixing plate into the outer case; and the second step of inserting the capacitor fixing plate into the outer case, thereby connecting the connecting means which is disposed on the part fixing plate, to the connecting portion of the capacitor. Therefore, it is not required to conduct cumbersome connecting works, particularly, soldering work, so that the production efficiency can be enhanced.

In the first part fixing plate for a flyback transformer of the invention, because of the connecting portion of the high-voltage output unit which is connected to the connecting portion of the capacitor which is separately formed, by moving the connecting portion of the capacitor to approach the connecting portion of the high-voltage output unit, it is not required to conduct cumbersome connecting works, particularly, a soldering work, so that the production efficiency can be enhanced.

In the second part fixing plate for a flyback transformer of the invention, since the connecting portion disposed in the high-voltage output unit has a needle-like shape, the connecting work can be conducted easily and surely.

In the third part fixing plate for a flyback transformer of the invention, since the connecting portion disposed in the high-voltage output unit is a single metal piece including the first and second connecting portions, parts can be shared, thereby contributing an improved efficiency of the connecting work.

Hereinafter, a flyback transformer of an embodiment of the invention will be described.

Fig. 1 is a view illustrating the vicinity of a connecting metal piece of the flyback transformer of an embodiment of the invention, Fig. 2 is a view illustrating the configuration of the flyback transformer, Fig. 3A is a side view showing the connecting metal piece of the flyback transformer, Fig. 3B is a bottom view of the connecting metal piece, Fig. 4A is a plan view of the vicinity of a capacitor fixing plate of the flyback transformer, Fig. 4B is a side view of the capacitor fixing plate, Fig. 4C is a bottom view of the capacitor fixing plate, and Fig. 5 is a view showing a positioning unit of an outer case of the flyback transformer.

In the figures, ip designates a ferrite core, 2p designates a primary winding, 3p designates a primary winding bobbin, 4p designates a secondary winding, 5p designates a secondary winding bobbin, 25p designates the coil body in which the primary and secondary winding bobbins 3p and 5p are fitted to each other, 6p designates rectifying devices which rectify an output pulse, 7p designates a high-voltage capacitor, 22p designates a connecting metal piece, 8p designates a part fixing plate to which the rectifying devices 6p, a protection resistor 12p, and the connecting metal piece'22p are to be fixed, 18p designates a high-voltage capacitor fixing plate to which the high-voltage capacitor 7p, a protection resistor 13p, and electrically conductive rubber llp are to be fixed, 9p designates an epoxy resin which is an insulating material, 10p designates an outer case, and 14p designates an insulating tube. These components constitute the FBT body.

A high-voltage product (not shown) is a solid wire in which the insulating cover at one end of a high-voltage conductor 16p is peeled off and an anode cap and an anode connecting metal piece are attached to the other end.

Furthermore, an insulating rubber cap is attached to a middle portion. When the high-voltage product is inserted into the insulating tube 14p of the FBT body, the tip end of the highvoltage product is inserted into a V-shaped portion 22pb of the connecting metal piece 22p which is inserted into the insulating tube 14p, thereby forming a configuration which can hold the high-voltage product and the FBT body.

Figs. 3A and 3B show a typical example of the connecting metal piece 22p having a needle-like portion 22pa, a shaped portion 22pb to which a high-voltage conductor can be connected, and a shaped portion 22pc to which one of the rectifying devices 6p can be connected.

The connecting metal piece 22p is attached to the part fixing plate 8p. The rectifying device 6p is attached to the connecting metal piece in such a manner that one lead of the rectifying device 6p is clamped by the shaped portion 22pc to which the rectifying device 6p can be connected. As a result, the electrical connection between the rectifying device 6p and the connecting metal piece 22p can be realized without using soldering.

The coil body 25p on which a part fixing plate product 23p is disposed is inserted into the outer case 10p or the insulating tube 14p attached to the outer case 10p. This causes a gap portion 8pa of the-part fixing plate 8p and the connecting portion 22pb of the connecting metal piece 22p to be pressingly inserted int tube 14p, whereby the connecting portion for the high-voltage conductor is formed and the FBT body is configured.

Figs. 4A to 4C show a typical example of a high-voltage capacitor connecting plate product 24p to which the conductive rubber llp is attached. A connecting metal piece 25p and the conductive rubber llp are attached to the high-voltage capacitor fixing plate 18p. Thereafter, the high-voltage capacitor 7p in which a high-voltage lead 7pa is cut into a given length (about 10 mm) is inserted into the high-voltage capacitor fixing plate so that the high-voltage lead 7pa is clamped by a clamping portion 25pa of the connecting metal piece 25p. A ground terminal 7pb is positionally fixed by inserting the terminal into an engagement portion 18pb of the high-voltage capacitor fixing plate 18p. One lead 13pa of the second protection resistor 13p straight elongate, and the other lead 13pb is bent by about 1200. The lead 13pa is clamped by a clamping portion 25pb of the connecting metal piece 25p, and the lead 13pb is inserted into the conductive rubber llp. A Tshaped rib 18pc and a protruding rib 18d are integrally formed on the rear side of the high-voltage capacitor fixing plate 18p.

Fig. 5 shows the high-voltage capacitor connecting plate product 24p which is separately formed, the part fixing plate product 23p, and a positioning unit formed on the outer case 10p. The T-shaped rib 18pc and the protrusion rib 18pd of the high-voltage capacitor connecting plate product 24p are inserted respectively along a T-shaped positioning recess lOpc and a positioning recess loped of the outer case 10p into which the FBT body is inserted. This causes the needle-like portion 22pa of the connecting metal piece 22p attached to the part fixing plate product 23p, to be inserted into the conductive rubber llp of the high-voltage capacitor connecting plate product 24p, thereby enabling the electrical connection therebetween. Furthermore, the positioning and fixation are attained by the recesses lOpc and loped of the outer case 10p and the T-shaped rib 18pc and the protrusion rib 18pd of the high-voltage capacitor fixing plate 18p. In order to insulate the high voltage portion, the FBT body is impregnated with the epoxy resin 9p which is an insulating material and the resin is then cured.

In this way, the soldering work which is necessary in the prior art is eliminated and the problems due to the work are reduced. Unlike the prior art method in which parts including a high-voltage capacitor are intensively processed on a single part fixing plate, the method of producing the flyback transformer is conducted in the following manner. The highvoltage capacitor 7p and associated parts are separated or disposed on the high-voltage capacitor connecting plate product 24p. The part fixing plate 8p (the part fixing plate product 23p) is inserted into the outer case lOp, and the high-voltage capacitor fixing plate 18p (the high-voltage capacitor connecting plate product 24p) is then inserted. Therefore, both the process of the part fixing plate 8p and that of the high-voltage capacitor fixing plate 18p do not require the soldering work and can be automatized, with the result that the production can be efficiently conducted. Among high-voltage capacitor connecting plate products 24p which are different from each other in shape and kind, when the connecting portions are shaped so as to be commonly used, the body parts including the high-voltage conductor connecting portion and the part fixing plate product 23p can be shared.

As apparent from the above description, in the first flyback transformer of the invention, since the connecting portion of the high-voltage capacitor which is separately formed can be connected to the part fixing plate by moving the connecting portion of the high-voltage capacitor to approach the part fixing plate, it is not required to conduct cumbersome connecting works, particularly, a soldering work, so that the production efficiency can be enhanced.

The method of producing a flyback transformer of the invention comprises the steps of: the first step of inserting the part fixing plate into the outer case; and the second step of inserting the capacitor fixing plate into the outer case, thereby connecting the connecting means which is disposed on the part fixing plate, to the connecting portion of the capacitor. Therefore, it is not required to conduct cumbersome connecting works, particularly, a soldering work, so that the production efficiency can be enhanced.

According to the configuration, in the first flyback transformer of the invention, since the faces of the two clamping portions which are in contact with the high-voltage output unit are flat and the clamped portion of the highvoltage output unit is flat, the high-voltage output unit is in close contact with the two clamping portions so that a gap is not formed. Therefore, resin leakage does not occur in a resin casting process.

In the second flyback transformer of the invention, since the tip end portion of each of the clamping portions is smaller in diameter than the body portion of the clamping portion, the clamping portions can be easily inserted into the insulating tube.

In the third flyback transformer of the invention, since the portion of the high-voltage output unit with which the high-voltage cable is engaged is projected from the clamping portions, sure insulation due to resin casting can be attained at the clamping portions and a resin is prevented from entering the portion with which the high-voltage cable is engaged.

Hereinafter, an embodiment of the invention will be described with reference to the drawings.

Fig. 9 is a view illustrating the configuration of a flyback transformer of an embodiment of the invention, Fig. 10 is a view showing clamping portions of a part.fixing plate of the flyback transformer, Fig. 11 is a view showing a connecting metal piece of a high-voltage output unit, Fig. 12A is a section view of the connecting metal piece of the high-voltage output unit, Fig. 12B is a section view of the clamping portions of the part fixing plate, Fig. 12C is a section view showing a state in which the connecting metal piece of the high-voltage output unit is combined with the clamping portions of the part fixing plate, and Fig. 13 is a view illustrating main portions of the flyback transformer in a connected state.

Referring to the figures, the flyback transformer of the embodiment of the invention comprises: an outer case 3q; a coil unit 7q including a primary coil bobbin lq on which a primary winding is wound, and a secondary coil bobbin 2q on which a secondary winding is wound in plural layers; a part fixing plate 4q having rectifying devices 25q which are respectively connected between the layers of the secondary winding, a resistor 26q, and a connecting metal piece 21q serving as the high-voltage output unit; and a hollow insulating tube 5q which is inserted into the outer case 3q and in which a through hole 5qd is formed at a part of a middle portion.

In Fig. 9, for the sake of description, the vicinity of the insulating tube 5q is shown in section. The connecting metal piece 21q serving as the high-voltage output unit is attached to the part fixing plate 4q. A V-shaped portion 21qa is disposed at the tip end of the metal piece. One end of the resistor 26q is connected to the connecting metal piece 21q.

The other end of the resistor 26q is connected to the rectifying device 25q which is on the highest voltage side.

The part fixing plate 4q has two clamping portions 4qc which clamp the connecting metal piece 21q serving as the highvoltage output unit and which have a semicylindrical section shape. The faces of the clamping portions 4qc which are in contact with the high-voltage output unit 21q are flat, and also a clamped portion 2lqb of the connecting metal piece 21q is flat. The width of the clamped portion 2lqb of the connecting metal piece 21q is approximately equal to the widths of the clamping portions 4qc, in an at least partial manner.

In the connecting metal piece 21q, the V-shaped portion 2lqa, the clamped portion 21qb, and a clamp-shaped portion 21qh which clamps the resistor lead are integrally formed.

The part fixing plate 4q to which the connecting metal piece 21q is attached is disposed in the coil unit body 7q.

The coil unit body 7q is then inserted into the outer case 3q into which the insulating tube 5q has been inserted. As a result, under the state in which the connecting metal piece 21q is clamped by the clamping portions 4qc of the part fixing plate 4q, the connecting metal piece is inserted into the inner end 5qb of the insulating tube 5q, thereby fixing the coil unit body 7q to the outer case 3q.

In order to prevent resin leakage from occurring, the internal dimension A of the inner end 5qb of the insulating tube, and the external dimension B of the clamping portions 4qc of the part fixing plate 4q are set so as to attain a degree of interference of A < B.

The edge of the inner end 5qb of the insulating tube 5q is chamfered, and the tip end of each of the clamping portions 4qc of the part fixing plate 4q, and that of the clamped portion 21qb of the connecting metal piece 21q serving as the high-voltage output unit are partly tapered. Therefore, the structure in which the clamping portions 4qc of the part fixing plate 4q, and the connecting metal piece 21q can be easily inserted into the insulating tube 5q is realized. A semicylindrical flange 4qh is formed integrally with the rear end (the side opposite to the tapered side) of each of the clamping portions 4qc. When the clamping portions are inserted into the insulating tube 5q, the flanges 4qh abut against the inner end 5qb of the insulating tube so as to be positioned.

In a case such as that the connecting metal piece 21q which is the high-voltage output unit attached to the part fixing plate 4q is inserted into the part fixing plate 4q by an automatic inserting machine, or that the connecting metal piece is disposed on the coil unit body, the connecting metal piece may be vertically displaced by vibration, movement of another member, or another cause. Since both the faces where the clamping portions 4qc is in contact with the clamped portion 21qb of the connecting metal piece 21q are flat, however, such displacement is absorbed when the connecting metal piece is inserted into the inner end 5qb of the insulating tube 5q.

Furthermore, the width of the clamped portion 21qb of the connecting metal piece 21q is approximately equal to the internal dimension A of the inner end 5qb of the insulating tube 5q, and hence the connecting metal piece 21q may bite in the inner wall 5qe of the inner end 5qb of the insulating tube 5q. Therefore, small displacement can be absorbed and the epoxy resin does not leak.

On the other hand, in the high-voltage product 15q, an anode cap 9q and an anode connecting metal piece 10q are attached to one end of the high-voltage cable 8q the core of which is a solid wire, and an insulating cover at the other end is peeled off so that only the core wire 8qa is projected. An insulating rubber cap 12q is fixed onto a middle portion of the high-voltage cable 8q so as to configure the high-voltage product 15q as a whole.

When the high-voltage product 15q is inserted into the outer case 3q, the core wire 8qa of the high-voltage cable 8q is inserted into the V-shaped portion 21qa which is at the tip end of the connecting metal piece 21q inserted into the insulating tube 5q, and the high-voltage product 15q and the outer case 3q are fixed to each other. In this way, the coil unit body 7q and the rectifying devices 25q are connected to the high-voltage product 15q via the connecting metal piece 21q. Since the connecting metal piece 21q has the V-shaped portion 2lqa, the core wire 8qa of the high-voltage cable 8q which is once inserted into the portion is hardly disengaged therefrom.

In the connecting metal piece 21q serving as the highvoltage output unit, the V-shaped portion 2lqa which is to be connected to the core wire 8qa of the high-voltage cable 8q may have any shape as far as it can hold and fix the core wire 8qa of the high-voltage cable 8q.

As described above, according to the configuration of the flyback transformer of the embodiment of the invention, the employment of the connecting metal piece 2lq as the highvoltage output unit realizes both the connection between the high-voltage product 15q and the high-voltage output unit in the flyback transformer, and the hold and fixation between the high-voltage product 15q and the FBT. Therefore, the number of the parts (the fixing sleeve 13q, the fixing sleeve 14q, and the arrow-shaped terminal llq) of the high-voltage product 15q can be reduced, and decrease of manpower due to the reduction is enabled.

Furthermore, the employment of the connecting metal piece 21q as the high-voltage output unit can reduce the amount of the conductive rubber, and also the manpower for inserting the insulating tube into the conductive rubber.

Since the connecting metal piece 21q of the highvoltage output unit and having the clamped portion 21qb which is flat is employed, the proportion defective of the insertion into the insulating tube 5q can be reduced by the automatic insertion into the part fixing plate 4q and also by the stabilized shape. As a result, it is not required to again conduct the check after the connecting metal piece 21q is inserted into the part fixing plate 4q.

The flat shape of the clamping portions 4qc of the part fixing plate 4q allows the clamping portions 4qc and the connecting metal piece 2lq of the high-voltage output unit to be stably housed in the insulating tube 5q, whereby the failure of leakage of the epoxy resin can be reduced.

As apparent from the above description, in the first flyback transformer of the invention, since the faces of the two clamping portions which are in contact with the high voltage output unit are flat and the clamped portion of the high-voltage output unit is flat, the high-voltage output unit is in close contact with the two clamping portions so that a gap is not formed. Therefore, resin leakage does not occur in a resin casting process.

Claims

1. A flyback transformer comprising: an outer case; a coil unit including at least a primary winding and a secondary winding having plural layers; rectifying devices which are respectively connected between the layers of said secondary winding; a high-voltage output unit for said secondary winding; and a part fixing plate in which said high-voltage output unit has a connecting portion, said connecting portion being connected to a connecting portion of said high-voltage capacitor which is separately formed, by moving said connecting portion of said high-voltage capacitor to approach said connecting portion of said high-voltage output unit.

2. The flyback transformer of claim 1, wherein said connecting portion disposed in said high-voltage output unit has a needle-like shape, and said connecting portion of said high-voltage capacitor is made of electrically conductive rubber.

3. The flyback transformer of claim 1, wherein said connecting portion disposed in said high-voltage output unit is a single metal piece including: a first connecting portion which is connected to said connecting portion of said high-voltage capacitor which is separately formed, by moving said connecting portion of said high-voltage capacitor to approach said first connecting portion; and a second connecting portion through which a high voltage is output to an outside.

4. The flyback transformer of any preceding clam, further canprising: a high-voltage capacitor fixing plate comprising; said high-voltage capacitor, and said connecting portion of said high-voltage capacitor, wherein said outer case comprises: a part fixing plate holding unit which directly or indirectly fixes a part fixing plate; and a positioning unit which positions at least a part of said high-voltage capacitor fixing plate.

5. A method of producing a flyback transformer comprising the steps of: a first step of inserting a part fixing plate in which connecting means is formed in a high-voltage output unit, into an outer case, said connecting means comprising: rectifying devices which are respectively connected between layers of a secondary winding; a high-voltage output unit for said secondary winding; and connecting means in said high-voltage output unit, said connecting means being connected to a connecting portion of a high-voltage capacitor which is separately formed, by moving said connecting portion of said high-voltage capacitor to approach said connecting means, and a second step of inserting a high-voltage capacitor fixing plate comprising; a high-voltage capacitor and said connecting portion of said high-voltage capacitor, into said outer case, so as to connect said connecting means disposed on said part fixing plate, to said connecting portion of said high-voltage capacitor.

6. A part fixing plate for a flyback transformer, comprising: rectifying devices which are respectively connected between layers of a secondary winding; a high-voltage output unit for said secondary winding; and a connecting portion disposed in said high-voltage output unit, said connecting portion being connected to a connecting portion of a high-voltage capacitor which is separately formed, by moving said connecting portion of said high-voltage capacitor to approach said connecting portion disposed in said high-voltage output unit.

7. The part fixing plate for a flyback transformer of claim 6, wherein said connecting portion disposed in said high-voltage output unit has a needle-like shape.

8. The part fixing plate for a flyback transformer of claim 6, wherein said connecting portion disposed in said high-voltage output unit is a single metal piece comprising: a first connecting portion which is connected to said connecting portion of said high-voltage capacitor which is separately formed, by moving said connecting portion of said high-voltage capacitor to approach said first connecting portion; and a second connecting portion through which a high voltage is output to an outside.

9. A flyback transformer comprising: an outer case; a coil unit including at least a primary winding and a secondary winding having plural layers; a part fixing plate having rectifying devices which are respectively connected between the layers of said secondary winding, and a high-voltage output unit for said secondary winding; and an insulating tube in which said high-voltage output unit is connected to a high-voltage cable, wherein said part fixing plate further comprising two clamping portions which are inserted into said insulating tube to clamp said high-voltage output unit, said clamping portions having a semicylindrical section shape, a face of each of said clamping portions which is in contact with said high-voltage output unit is flat, a clamped portion of said high-voltage output unit is flat, and said clamping portions are approximately equal in width to said clamped portion of said high-voltage output unit, in an at least partial manner.

10. The flyback transformer of claim 9, wherein a diameter of a tip end portion of each of said clamping portions is smaller than a diameter of a body portion of said clamping portion.

11. The flyback transformer of claim 9 or 10, wherein a portion of said high-voltage output unit with which said high-voltage cable is engaged is projected from said clamping portions.

12. A flyback transformer substantially as described with reference to Figures 1 to 5 or 9 to 13 of the accompanying drawings.

13. A part fixing plate substantially as described with reference to Figures 1 to 5 or 9 to 13 of the accompanying drawings.