JP2548955Y2 - Power transformer - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a power transformer suitable for use in, for example, a high-frequency switching power supply device.

[Prior Art] FIG. 3 shows an example of a power transformer.

In the figure, 1 is an E-type ferrite core, 2 is an I-type ferrite core, and 3 is a bobbin provided with a cylindrical portion around which a copper wire is wound and terminals. Reference numeral 4 denotes a spacer inserted between the ferrite cores 1 and 2 for providing a gap for extending the current superposition characteristics of the ferrite cores 1 and 2.

[Problem to be Solved by the Invention] Meanwhile, in a switching power supply device, it is conceivable to increase the switching frequency to reduce the number of windings of the power supply transformer and to reduce its size.
However, according to the power transformer having a configuration in which a copper wire is wound around the bobbin 3 as shown in FIG. 3, when the switching frequency increases, a skin effect occurs on the copper wire, and the utilization efficiency of the copper wire is significantly reduced. The fever increases. In other words, this skin effect is an obstacle to increasing the switching frequency, and thus reducing the size of the power transformer and the like.

Thus, the present invention provides a power transformer capable of suppressing the occurrence of the skin effect.

[Means for Solving the Problems] In order to solve the above-mentioned problems, in the present invention, a printed board having a predetermined thickness is arranged between the first core and the second core, and the printed board is provided on the printed board. In each of the first and second cores, a spiral-shaped conductive pattern as a primary coil and a spiral-shaped conductive pattern as a secondary coil are arranged in parallel at positions facing different magnetic path surfaces. The area of the magnetic path surface facing the conductive pattern has a size that can cover the conductive pattern.

[Operation] In the configuration described above, the conductive pattern formed in a spiral shape on the printed circuit board functions as a winding. Therefore, the winding is formed in a planar shape, and the skin effect that occurs when the oscillation frequency of the power supply is increased is suppressed, and a decrease in the usage efficiency of the winding is suppressed.

Further, the printed circuit board that cuts the magnetic path formed by the first core and the second core also has a spacer function for extending current superimposition characteristics.

[Embodiment] An embodiment of the present invention will be described below with reference to FIGS. 1 and 2. FIG. These FIGS. 1 and 2
In the figure, parts corresponding to those in FIG. 3 are denoted by the same reference numerals.

Numeral 1 is a U-shaped ferrite core having a depression 1c formed in the center. As shown in FIG. 2, magnetic path surfaces 1a and 1b are formed on both sides of the depression 1c. Numeral 2 denotes a U-shaped ferrite core similar to the core 1, and magnetic path surfaces 2a and 2b corresponding to the magnetic path surfaces 1a and 1b of the core 1 are formed on both sides of the central recess 2c. These magnetic path surfaces 1a, 1b, 2a, 2b are widened to increase the passage of magnetic flux. That is, it has an area capable of covering a spiral-shaped conductive pattern formed on a printed board described later. Therefore, both cores
1 and 2 are thinner than before.

Reference numeral 5 denotes a flexible printed circuit board having substantially the same size as the cores 1 and 2, and is inserted between the cores 1 and 2.

On the surfaces of the printed circuit board 5 facing the magnetic path surfaces 1a, 2a, 1b and 2b, conductive patterns 5a and 5b on which copper foil is printed in a spiral shape are formed. The magnetic path surfaces 1a, 2a, 1b, 2b of the core 1 and the core 2 described above are arranged so as to cover the conductive pattern.

The printed circuit board 5 is provided with primary terminals 5c and 5d and secondary terminals 5e and 5f protruding from the longitudinal direction of the printed circuit board 5.

In this example, the printed circuit board 5 on which the conductive patterns 5a and 5b of the spiral copper foil are formed between the core 1 and the core 2 is formed.
Are inserted, and both cores facing the conductive patterns 5a and 5b are inserted.
The first and second magnetic path surfaces 1a, 1b, 2a, 2b are provided so as to cover the conductive patterns 5a, 5b. Therefore, when a voltage is applied to the primary terminals 5c and 5d and a current flows through the conductive pattern 5a, a magnetic flux is generated, and the magnetic flux is transmitted through the cores 1 and 2 to the conductive pattern 5b.
Pass through. As a result, a voltage is generated at the secondary terminals 5e and 5f.

Therefore, it functions similarly to the power transformer of the example of FIG. Note that the printed circuit board 5 also serves as a spacer in the example of FIG.

According to this example, the spirally formed conductive patterns 5a and 5b of the printed board 5 function as windings. That is, since the winding is formed in a planar shape, for example, even if the switching frequency is increased in the switching power supply device, the skin effect is suppressed, and a decrease in the use efficiency of the winding is suppressed. Accordingly, the oscillation frequency of the power supply can be increased, and the size of the power transformer can be reduced.

Further, according to the present example, the oscillation frequency of the power supply can be increased, and thereby the components of the capacitance and the filter system constituting the power supply device can be reduced in size.

Furthermore, according to this example, the winding is formed by the printed circuit board 5, and the printed circuit board 5 also has the function of the spacer, so that the structure of the power transformer can be simplified. Therefore, according to the present embodiment, the number of parts can be reduced, and it can be manufactured more easily and inexpensively than the conventional one.

In the above embodiment, both cores 1 and 2 have a U-shape, but the shape of the core is not limited to this, and may be an E-shape or an I-shape. . Also,
In the above embodiment, the printed circuit board 5 is flexible, but is not limited to this, and may be paper phenol, glass, or the like. In short, the present invention can be similarly applied as long as the thickness can be controlled to some extent.

[Effects of the Invention] As described above, according to the invention, the planar conductive pattern formed in a spiral shape on the printed circuit board functions as a winding, and therefore, when the oscillation frequency of the power supply increases, The generated skin effect is suppressed, and a decrease in the use efficiency of the winding is suppressed. Therefore, the frequency can be increased, and the size of the power transformer and the like can be reduced.

In addition, according to the present invention, the winding process is not required because the winding is formed by the printed board, and the printed board plays a role of a spacer. It is simple, easy and inexpensive to manufacture.

[Brief description of the drawings]

FIG. 1 is a perspective view of an embodiment of the present invention, FIG. 2 is an exploded perspective view thereof, and FIG. 3 is a perspective view of a conventional example. 1,2 ... ferrite core 1a, 1b, 2a, 2b ... magnetic path surface 5 ... printed circuit board 5a, 5b ... conductive pattern

Claims (1)

(57) [Scope of request for utility model registration] 1. A printed circuit board having a predetermined thickness is disposed between a first core and a second core, and the printed circuit board has a primary side coil at a position facing a different magnetic path surface. A spiral-shaped conductive pattern and a spiral-shaped conductive pattern as a secondary coil are arranged in parallel, and the area of the magnetic path surface of the first and second cores facing the conductive pattern covers the conductive pattern. A power transformer characterized in that it can be sized.