JPH0945550A - High-frequency transformer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a high-frequency transformer which is easy to assemble, lower in production cost and easy to miniaturize and flatten, and generates no noise. SOLUTION: In a high-frequency transformer 1 including a bobbin with brim 2, a coil 3 and a pair of ferrite cores 4, an insulating cover 5 is provided between the outer surface of the bobbin with brim 2 and the inner side of the pair of ferrite cores 4. The insulating cover 5 covers the entire outer side and upper side of the bobbin with brim 2. The insulating cover 5 is engaged with a part of the bottom of the bobbin with brim 2 so as to be fixed to the bobbin with brim 2.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a high frequency transformer used in various electronic devices, and more particularly to a high frequency transformer in which insulation between a ferrite core and a coil is extremely good.

[0002]

2. Description of the Related Art A set of ferrite cores composed of a combination of E-type ferrite cores, a set of ferrite cores composed of a combination of an E-type ferrite core and an I-type ferrite core,
Or, a high frequency transformer that uses a set of ferrite cores that are slightly modified in shape forms a coil by winding on a bobbin with a collar that has a hollow portion, and insulates the ferrite core from the outside of this coil. It is assembled by winding the insulating tape for goodness several times and then inserting the middle leg of the E-type ferrite core into the hollow portion of the bobbin.

Further, in a high frequency transformer in which the output is high and the breakdown voltage between the winding and the ferrite core must be high, an insulating cover made of synthetic resin is provided between the outer surface of the bobbin and the inner surface of the ferrite core. Some of them are installed to secure the withstand voltage between the ferrite core and the winding (for example,
See Japanese Utility Model Laid-Open No. 3-51821). The insulating cover is configured to extend along the ferrite core facing surface of the bobbin to cover the outer surface of the bobbin, and a frame-shaped portion provided with a through window at a position corresponding to the hollow portion of the bobbin. The frame-shaped part is integrally formed with a projecting part that projects from the upper and lower ends to the outer periphery and covers the upper and lower surfaces of the ferrite core.

[0004]

However, in the case of a high frequency transformer in which an insulating tape is wound around the outer circumference of a coil several times, the insulating effect between the coil and the core and the creepage distance cannot be sufficiently secured. Recently, there have been many cases where ultra-small size and flat type are required, and the outer circumference of the coil is often narrowed to the outer circumference of the flange, which is a drawback that the creepage distance tends to be insufficient. Further, in manufacturing, since several layers are carefully wound around the outer circumference of the coil without sticking out of the insulating tape, the process takes time and the manufacturing cost becomes high.

Further, in the high frequency transformer formed by covering the insulating cover made of synthetic resin described above, when the bobbin terminal plate is long, it is difficult to press both cores with the pad of the finger when assembling the cores, and the process takes time. In addition, since it is only inserted between the core and the bobbin, there is a problem that an abnormal noise is generated when the circuit is operated unless a process such as impregnation or adhesion is included.

Therefore, the object of the present invention is to improve the above-mentioned drawbacks and satisfy the requirements, so that the assembly is easy and the manufacturing cost is low, the miniaturization and the flattening can be easily realized, and the abnormal noise is generated. To provide a high frequency transformer that does not.

[0007]

According to the present invention, a bobbin with a collar having a hollow portion formed in a central portion, a plurality of collars, and terminal plate portions formed on the collars located at both ends, A coil configured by winding the collared bobbin between the collars, and a pair of ferrite cores that are mounted on the collared bobbin and abut against each other to form a closed magnetic circuit, and at least one of A high frequency transformer including a pair of ferrite cores, which are E-type ferrite cores having a middle leg inserted into the hollow portion and a pair of side legs arranged on both sides of the middle leg, and an outer surface of the collared bobbin. An insulating cover is provided that is interposed between the inner surfaces of the pair of ferrite cores, covers the entire outer surface and upper surface of the collared bobbin, and engages with a part of the bottom surface of the collared bobbin. Is a high frequency transformer can be obtained, characterized by that.

According to the present invention, in the high frequency transformer, the pair of ferrite cores are both E
A high frequency transformer is obtained which is a type ferrite core.

Further, according to the present invention, in the above high frequency transformer, one of the pair of ferrite cores is an E type ferrite core and the other is an I type ferrite core.

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described with reference to the drawings. 1 is an exploded perspective view of a high-frequency transformer according to a first embodiment of the present invention, FIG. 2 is a cross-sectional view of the high-frequency transformer shown in FIG. 1, and FIG. 3 is a bottom view of an insulating cover of the high-frequency transformer shown in FIG. It is a perspective view. 1 to 3, the high frequency transformer 1 includes a bobbin 2 with a collar.
A coil 3, a pair of ferrite cores 4, and an insulating cover 5.

The collared bobbin 2 has a hollow portion 20, a plurality of collars 21, and a terminal plate portion 22. Hollow part 20
Is a rectangular tubular body 2 located at the center of the collared bobbin 2.
3. Four flanges 21 are provided on the body portion 23 at predetermined intervals. The terminal plate portion 22 has a body portion 23.
Is formed on the lower part of the collar 21 located at both ends of the. A pin-shaped terminal 24 is embedded in the terminal plate portion 22.

The coil 3 has a bobbin 2 with a collar between the collars 21.
It is composed of three windings. The end of each coil 3 is entwined with the terminal 24.

In the present embodiment, the pair of ferrite cores 4 are both E-type ferrite cores. Each E-type ferrite core 4 has a middle leg 40 and a side leg 41. The middle leg 40 is a part that is inserted into the hollow portion 20 of the collared bobbin 2 when the E-type ferrite core 4 is mounted on the collared bobbin 2. There are a pair of side legs 41, which are arranged on both sides of the middle leg 40. The pair of E-type ferrite cores 4 are mounted on a bobbin 2 with a collar on which a winding is applied, and end faces thereof are abutted against each other to form a closed magnetic circuit.

The insulating cover 5 is made of insulating and elastic synthetic resin. The insulating cover 5 has an upper plate portion 50.
And a side plate portion 51, an end plate portion 52, and a bottom plate portion 53. The upper plate portion 50 covers the entire upper surface of the collared bobbin 2 and the entire upper surfaces of the pair of E-type ferrite cores 4 mounted on the collared bobbin 2. The side plate portions 51 are oppositely provided on the upper plate portion 50 so as to face each other. Notches 51a for receiving the terminal plate portions 22 of the collared bobbin 2 are formed at both ends of each side plate portion 51. The end plate portion 52 is
One opposite plate is provided on the upper plate portion 50 to connect the both side plate portions 51. A notch 52a is formed in the end plate portion 52 at a portion corresponding to the hollow portion 20 of the collared bobbin 2. The both side plate portions 51 and both end plate portions 52 are interposed between the outer side surface of the collared bobbin 2 and the inner side surfaces of the pair of E-type ferrite cores 4. Here, the “outer surface of the bobbin 2 with the collar” means the body portion 2
3, both side surfaces of the collared bobbin 2 parallel to the central axis direction of the collar 3, and both end surfaces of the collared bobbin 2 in the central axis direction of the body portion 23 (excluding both end surfaces of the terminal plate portion 22),
In addition, "the inner surface of the pair of E-type ferrite cores 4" means
It means the surface of the E-type ferrite core 4 facing the outer surface of the collared bobbin 2 when the E-type ferrite core 4 is mounted on the collared bobbin 2. The side plate portions 51 and the both end plate portions 52 cover the entire outer surface of the collared bobbin 2. The bottom plate portion 53 is continuously provided at the lower edge of each side plate portion 51, and engages with the bottom plate portion 53 so as to cover a part of the bottom surface of the collared bobbin 2. In this manner, the bottom plate portion 53 engages with a part of the bottom surface of the collared bobbin 2 so that the insulating cover 5 is locked to the collared bobbin 2.

FIG. 4 is a cross-sectional view of the high frequency transformer according to the second embodiment. The present embodiment has substantially the same configuration as that of the first embodiment, and portions corresponding to those of the first embodiment are designated by the same reference numerals as those of the first embodiment and their description is omitted, and the configuration is different. Only the part will be described.

In the case of the high frequency transformer 1 of this embodiment, the shape of the pair of E-type ferrite cores 4 is slightly changed from that of the first embodiment. That is, in the case of this embodiment, E
The cross-sectional shapes of the middle leg 40 and the side legs 41 of the type ferrite core 4 are different from those of the first embodiment. In the case of the first embodiment, the cross-sectional shape of the middle leg 40 and the side leg 41 is rectangular, but in the case of the present embodiment, the cross-sectional shape of the middle leg 40 is oval, and the lateral leg 41 crosses. The surface shape is recessed inside so as to correspond to the middle leg 40. As described above, in this embodiment, the shape of the pair of E-type ferrite cores 4 is slightly changed from that of the first embodiment, and accordingly, the cross-sectional shape of the body portion 23 of the collared bobbin 2 is accordingly changed. Becomes an oval shape, and the shape of the coil 3 also becomes an oval shape. Further, the collar 21 of the bobbin 2 with a collar bulges corresponding to the coil 3 and the side plate portion 51 of the insulating cover 5 is curved. .

In the first and second embodiments,
Although a pair of E-type ferrite cores is used as the pair of ferrite cores, the pair of ferrite cores is not limited to this, and a combination of an E-type ferrite core and an I-type ferrite core may be used. A combination of the I-type ferrite core and the one shown in FIG. 3 may be slightly modified in shape.

[0018]

In the case of the high frequency transformer of the present invention, first,
A coil is constructed by winding a wire between the collars of a collared bobbin, and the ends of the coil are wired to the terminals of the terminal board, and then the insulation cover is put on the collared bobbin from above. Since the core is attached to the bobbin with the collar, the creepage distance between the winding and the side leg of the ferrite core can be made larger than the thickness of the insulating cover, and the troublesome work of winding the insulating tape can be omitted. Because of this,
The high frequency transformer can be easily miniaturized and flattened.
Also, the bottom plate of the insulating cover is designed to engage with the collared bobbin, and the insulation cover is designed to hold the ferrite core together with the ferrite core. The abnormal noise during the operation of the transformer due to the rattling of the core and the insulating cover is also eliminated.

As described above, the creepage distance between the coil and the ferrite core can be secured more than the wall thickness of the insulating cover, the troublesome tape winding work at the time of assembly can be omitted, and the bobbin with the collar and the ferrite core can be joined together. It's strong, the insulation is reliable,
A high-frequency transformer that is inexpensive, easy to miniaturize and flatten, and does not generate abnormal noise is obtained, and the practical effects of the present invention are great.

[Brief description of drawings]

FIG. 1 is an exploded perspective view of a high frequency transformer according to a first embodiment of the present invention.

FIG. 2 is a cross-sectional view of the high frequency transformer shown in FIG.

FIG. 3 is a perspective view of an insulating cover of the high frequency transformer shown in FIG. 1 viewed from below.

FIG. 4 is a transverse sectional view of a high frequency transformer according to a second embodiment.

[Explanation of symbols]

 1 high frequency transformer 2 bobbin with a collar 3 coil 4 E-type ferrite core 5 insulating cover 20 hollow part 21 collar 22 terminal plate part 40 middle leg 41 side leg 50 upper plate part 51 side plate part 52 end plate part 53 bottom plate part

Claims (3)

[Claims] 1. A hollow portion formed in a central portion, a plurality of collars,
And a bobbin with a collar having terminal plate portions formed on the collars located at both ends, a coil configured by winding the collared bobbin between the collars, and a coil attached to the collared bobbin. An E-type ferrite having a pair of ferrite cores forming a closed magnetic circuit by abutting each other, and having at least one middle leg inserted into the hollow portion and a pair of side legs arranged on both sides of the middle leg. In a high frequency transformer including a pair of ferrite cores, which are cores, are interposed between the outer surface of the collared bobbin and the inner surface of the pair of ferrite cores, and cover the entire outer surface and upper surface of the collared bobbin. At the same time, the high frequency transformer is provided with an insulating cover that engages with a part of the bottom surface of the collared bobbin. 2. The high frequency transformer according to claim 1, wherein the pair of ferrite cores are both E-type ferrite cores. 3. The high frequency transformer according to claim 1, wherein one of the pair of ferrite cores is an E-type ferrite core and the other is an I-type ferrite core.