JP2009224815A - Anti-magnetic type thin transformer - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To achieve the miniaturization and thinning of a transformer and reduction of the height thereof, and reduce leakage flux. <P>SOLUTION: A primary winding 12 and a secondary winding 13 formed flatly by a fused insulation wire are concentrically mounted around a pan-like core 1, and a stepped concave portion 5 is formed at two sides of an outer circumferential frame-like section 3 facing each other and a tabular core 7 is fitted. The tabular core is sandwiched and fixed with two bases 8 to tightly seal the opening surface of the core 1. In addition, the core 7 and bases 8 are formed so as to be almost flush with each other, and each terminal of the winding 12 and winding 13 is led out outside the core 1 from a winding storage section 4 through trenches 10 of the bases 8 and is connected to a terminal 9. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a transformer used in a switching power supply device or the like.

  In recent years, with the reduction in size and weight of electronic devices, transformers and coils used in these devices are also required to be reduced in size, thickness, and height.

For example, as shown in FIG. 1, the conventional transformer includes a drum core 21 having a flange on the upper and lower sides, a primary winding 24 and a secondary winding 25 that are concentrically wound around a winding shaft portion of the drum core 21, and a drum core 21. The base 23 includes a base 23 to be fixed and a ring core 22 attached to the outer periphery of the drum core 21. The base 23 is provided with a terminal 26 for connecting a primary winding 24 and a secondary winding 25.
Reference numeral 27 denotes a gap formed between the upper collar of the drum core 21 and the upper end portion of the ring core 22.

In the transformer having the above-described configuration, magnetic flux easily leaks from the upper gap portion to the outside, and there is a high possibility that surrounding electronic components are subject to magnetic interference.
In order to reduce this leakage magnetic flux, a shield sheet is put on the upper surface of the transformer. However, if the shield sheet is put, a problem arises in that the electrical characteristics of the transformer change.

  The transformer of FIG. 2 in which the same reference numerals are attached to the same parts as in FIG. 1 covers the drum core 21 around which the primary winding 24 and the secondary winding 25 are wound, and covers the bottomed cylindrical cap core 28 with a gap. 27 is formed between the lower arm of the drum core 21 and the inner periphery of the opening of the cap core 28, the leakage flux to the outside can be reduced, but the height of the entire transformer is increased by the thickness t of the upper surface of the cap core 28. There was a problem of going against low profile.

  In addition, what was described in the following patent documents 1-3 is known as another prior art.

Japanese Patent Laid-Open No. 7-23559 Japanese Utility Model Publication No. 7-32912 JP-A-7-288213

  The present invention has been made to solve the above-described problems of the conventional transformer, and its purpose is to reduce the leakage flux to the outside and reduce the overall height (thickness) of the transformer. That is.

The magnetic-shield type thin transformer according to claim 1 is a dish-shaped core in which a concave winding storage portion is formed between a central leg portion protruding from an opening surface and an outer peripheral frame portion; A closed magnetic circuit magnetic-shielding type formed of a flat primary winding and a secondary winding concentrically mounted in a winding housing portion of the core, and a plate-like core covering the upper surface of the central leg portion of the dish-shaped core. In thin transformers,
The dish-shaped core includes stepped recesses that are fitted to the plate-shaped core on two opposite sides of the outer peripheral frame portion,
The plate-shaped core is sandwiched between the outer peripheral frame portion and two bases, and the opening surface of the dish-shaped core is sealed by the plate-shaped core and the two bases, and the plate-shaped core The two bases are attached so as to be flush with each other,
The two bases are provided with surface-mounted terminals for connecting the primary winding and the secondary winding, and the terminals of the primary winding and the secondary winding are connected to the terminals. , A groove is provided through which the terminal pulled out from the winding housing portion is passed,
Furthermore, the plate-shaped core has a width that fits into the stepped recess of the dish-shaped core, and when fitted into the stepped recess, a gap is formed between the inner side surface and the central leg. It is characterized by having been comprised.

  The thin transformer according to claim 2 has a hole or a step formed in the outer peripheral frame portion of the dish-shaped core and an engaging portion corresponding to the hole or the step in each of the two bases. It is characterized in that the base is positioned and attached to the outer peripheral frame portion of the dish-shaped core, and the attachment position of the base can be made constant by configuring in this way.

  The thin transformer according to claim 3 uses an insulating ferrite core as the material of the plate-like core and the plate-like core, and omits the bobbin for mounting the primary winding and the secondary winding. be able to.

  As described above, in the present invention, the dish-shaped core 1 and the plate-shaped core 7 are formed of an insulating ferrite core, and the primary winding 12 and the secondary winding 13 are self-bonding insulated wires. The plate-shaped core 7 is formed in a flat shape, directly and concentrically mounted on the central leg 2 of the dish-shaped core 1, and the plate-shaped core 7 is formed on the opposite side of the outer peripheral frame 3 of the dish-shaped core 1. 5 so that it is not necessary to use a conventional bobbin or drum core, the number of parts can be reduced, and since the bobbin or drum core is not used, only the thickness of those ridges The height (thickness) dimension can be reduced.

Further, since the opening surface of the dish-shaped core 1 is sealed by the plate-shaped core 7 and the base 8, leakage magnetic flux to the outside can be reduced.
Furthermore, since the plate-like core 7 only needs to be large enough to cover the upper surface portion of the central leg portion 2 of the dish-like core 1, the overall manufacturing cost can be reduced.

FIG. 1 is an explanatory sectional view showing an example of a conventional transformer. FIG. 2 is a cross-sectional explanatory view showing another example of a conventional transformer. FIG. 3 shows an example of a dish-shaped core related to the thin transformer of the present invention, in which (a) is a sectional side view and (b) is a front view. FIG. 4 shows a plate-like core related to the thin transformer of the present invention, where (a) is a sectional side view and (b) is a front view. 5A and 5B are views showing the assembled state of the thin transformer of the present invention, where FIG. 5A is a sectional side view, and FIG. 5B is a bottom view.

Hereinafter, embodiments of the present invention will be described with reference to FIGS.
The magnetic-shield type thin transformer of the present invention includes a dish-shaped core 1, a plate-shaped core 7, two bases 8, a primary winding 12, and a secondary winding 13. Is formed of an insulative ferrite core, for example, a nickel-based ferrite core, and the dish-shaped core 1 has a concave winding between the central leg portion 2 projecting from the opening surface and the outer peripheral frame portion 3. A storage portion 4 is formed, and a primary winding 12 and a secondary winding 13 wound in a flat shape by a self-bonding insulated wire are concentrically mounted on the winding storage portion 4. . Reference numeral 5 denotes a step recess formed in two opposite sides of the outer peripheral frame portion 3 of the dish-shaped core 1, and reference numeral 6 denotes a step portion or hole formed in the outer peripheral frame portion.

  The plate-like core 7 has a width that fits into the stepped recess 5 of the dish-like core 1, and when fitted into the stepped recess 5, a gap g is formed between the inner side surface and the center leg 2. It is. The base 8 has a flat plate shape, a groove 10 for pulling out the terminals of the plurality of terminals 9, the primary winding 12 and the secondary winding 13, and a step or hole 6 formed in the outer peripheral frame portion 3 of the dish-shaped core 1. An engaging portion 11 such as a protrusion that engages with is provided.

An assembly process of the magnetic-shielding thin transformer having the above-described configuration will be described with reference to FIG.
First, the primary winding 12 and the secondary winding 13 are inserted into the central leg portion 2 of the dish-shaped core 1 and mounted concentrically on the winding storage portion 4.
Next, the plate-like core 7 is fitted and mounted between the stepped recesses 5 formed in the outer peripheral frame portion 3 of the dish-like core 1 and fixed with an adhesive.

  At this time, a gap g is formed between the back side of the plate-shaped core 7 and the front end surface of the central leg 2, and thus the dish-shaped core 1 and the plate-shaped core 7 form a closed magnetic path through the gap g. Then, the side 15 of the two bases 8 on which the terminal 9 is not projected is fixed to the side 16 of the plate-like core 7 and the engaging portion 11 is engaged with the stepped portion or hole 6 of the plate-like core 1. 8 is positioned and fixed to the outer peripheral frame portion 3 of the dish-shaped core 1, and the opening surface of the dish-shaped core 1 is sealed by the plate-shaped core 7 and the two bases 8.

The plate core 7 and the base 8 are substantially flush with each other.
Further, each end of the primary winding 12 and the secondary winding 13 is drawn out of the dish-shaped core 1 from the winding housing 4 through the groove 10 of the base 8 and connected to the terminal 9.

DESCRIPTION OF SYMBOLS 1 ... Plate-shaped core 2 ... Center leg part 3 ... Outer frame part 4 ... Winding storage part 5 ... Step recessed part 6 ... Step part or hole 7 ... Plate-shaped core 8 ... Base 9 ... Terminal 10 ... Groove 11 ... Locking part 12 ... Primary winding 13 ... Secondary winding

Claims (3)

A dish-shaped core in which a concave winding housing portion is formed between the central leg portion protruding from the opening surface and the outer peripheral frame portion, and is wound in advance and concentrically mounted on the winding housing portion of the dish-shaped core. In a closed magnetic path magnetic shield type thin transformer formed from a flat primary winding and a secondary winding, and a plate-like core covering the upper surface of the central leg of the dish-shaped core,
The dish-shaped core includes stepped recesses that are fitted to the plate-shaped core on two opposite sides of the outer peripheral frame portion,
The plate-shaped core is sandwiched between the outer peripheral frame portion and two bases, and the opening surface of the dish-shaped core is sealed by the plate-shaped core and the two bases, and the plate-shaped core The two bases are attached so as to be flush with each other,
The two bases are provided with surface-mounted terminals for connecting the primary winding and the secondary winding, and the terminals of the primary winding and the secondary winding are connected to the terminals. , A groove is provided through which the terminal pulled out from the winding housing portion is passed,
Furthermore, the plate-shaped core has a width that fits into the stepped recess of the dish-shaped core, and when fitted into the stepped recess, a gap is formed between the inner side surface and the central leg. A magnetically shielded thin transformer characterized by being configured as described above.   A hole or a step is formed in the outer peripheral frame portion of the dish-shaped core, and an engagement portion corresponding to the hole or the step portion is formed in each of the two bases, and the two bases are used as the outer frame portion of the dish-shaped core. 2. The magnetic-shield type thin transformer according to claim 1, wherein the transformer is positioned and attached. 3. The magnetic shield type thin transformer according to claim 1, wherein a ferrite core having an insulating property is used as a material for the dish-shaped core and the plate-shaped core.

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