JP2003031420A - Small transformer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make a small transformer compact and thinned. SOLUTION: The transformer comprises inner core (1, 2) composed of center cores (5, 6) each having an approximately elliptical or rectangular shape combined with a semicircular shape connected to both ends of the major axis in a section cut along the center axis, and flanges (7, 8, 9, 10) located at both ends of the center cores (5, 6); coils wound around the center cores 5, 6 of the inner cores (1, 2); and side cores (3, 4) connected to the flanges (7, 8, 9, 10) a both ends of the inner cores (1, 2).

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a small and thin transformer used for portable small equipment.

[0002]

2. Description of the Related Art Small transformers are used, for example, for inverters that drive electroluminescent plates used as backlights for liquid crystal display panels, and are often incorporated in small portable equipment such as mobile phones and digital cameras. The transformer itself is required to be smaller and thinner. Conventionally, this type of small transformer has a structure as shown in FIGS. 7 and 8.

FIG. 7 is a perspective view of a conventional small transformer, and FIG.
Shows a cross-sectional view of the small transformer shown in FIG. 7 taken along a plane parallel to the plane of the drawing when viewed from above. E made of soft magnetic material
A coil 34 wound around a bobbin 33 is mounted on the mold cores 31 and 32, and is wound and fixed by a transformer tape 35 as shown in FIG.

[0004]

However, the conventional small-sized transformer described above has a critical dimension in which the thickness of the cylindrical portion of the bobbin 33 can be reduced because of the resin flowability and the shape retention during the molding of the bobbin 33. It was difficult to reduce the thickness.

However, in recent years, small-sized portable devices such as mobile phones and digital cameras have been made smaller and thinner, and there has been a demand for even smaller small-sized transformers.

An object of the present invention is to solve the above problems by
The purpose is to further reduce the size and thickness of the small transformer.

[0007]

In order to solve the above problems, the small transformer of the present invention adopts the structure described below.

The small-sized transformer of the present invention has a middle core composed of a center core portion having a substantially elliptical cross section in the center axis and a brim portion at both ends of the center core portion, and a core wound around the center core portion of the middle core. And a side core connected to the brim portions at both ends of the middle core.

The small-sized transformer of the present invention comprises a central core part having a rectangular cross-section of the central axis and a semi-circular shape connected to both ends of the major axis, and a brim part at both ends of the central core part. It is characterized by comprising a middle core, a coil wound around a central core portion of the middle core, and side cores connected to the brim portions at both ends of the middle core.

The compact transformer of the present invention is characterized in that the central core portion and the brim portion of the middle core are integrally formed.

In the small transformer according to the present invention, the middle core is integrally formed in a bilaterally symmetrically cut shape with the minor axis portion as the center, and the minor axis portions of the two intermediate cores are combined to form a coil. It is characterized by being wound.

In the present invention, since the cross-sectional shape of the middle core is a substantially elliptical shape having no corners or edges, a bobbin is not required and it is possible to reduce the size and thickness. Further, the middle core and the side cores are not required to have a particularly difficult shape and configuration.

[0013]

BEST MODE FOR CARRYING OUT THE INVENTION The structure of a small transformer in the best mode for carrying out the present invention will be described below with reference to the drawings. FIG. 1 is a perspective view of a middle core and a side core of a first embodiment constituting a small transformer of the present invention, and FIG. 2 is a sectional view using the middle core of the first embodiment of the small transformer of the present invention. FIG. 3 is a sectional view using a middle core of a second embodiment of the small transformer of the present invention, and FIG. 4 is a perspective view of a middle core and a side core of a third embodiment of the small transformer of the present invention. FIG. 5 is a cross-sectional view using a middle core of a third embodiment of the small transformer of the present invention, and FIG. 6 is a cross-sectional view using a middle core of the fourth embodiment of the small transformer of the present invention. Hereinafter, description will be made with reference to FIGS. 1 to 6 as appropriate.

A small transformer using the middle core of the first embodiment will be described. In the perspective view of FIG. 1, the core of the small transformer includes middle cores 1 and 2 and side cores 3 and 4 of the first embodiment. The middle core 1 has a central core portion 5 formed by a combination of a rectangular cross-sectional shape of the central axis and a semi-circular shape connected to the ends of the long axis, and a semi-circular shape outside on the long axis sides of both ends of the central core portion 5. And brim 7 provided over the short axis side
Similarly, the middle core 2 has a central core portion 6 formed of a combination of a rectangular cross-sectional shape of the central axis and a semicircular shape connected to the ends of the long axis, and the lengths of both ends of the central core portion 6. It is composed of brim portions 8 and 10 provided on the outer side of the semicircular shape on the shaft side and on the short axis side.

The plane portions of the two inner cores 1 and 2 are aligned with each other, and as shown in FIG. 2, the central axes of the inner cores 1 and 2 are fixed by winding an under winding tape 11. Next, the coil 12 is formed by winding the winding wire 11 around the central core portions 5 and 6 which are formed by winding the unwinding tape 11. The side core 3 is arranged at the end of the middle core 1, and the side core 4 is arranged at the end of the middle core 2 in parallel with the central axes of the middle cores 1 and 2. Note that both of the side cores 3 and 4 are not always necessary, and either side core 3 or 4 may be omitted and only one side core may be provided. The outer sides of the middle cores 1 and 2 and the side cores 3 and 4 are wound with a transformer tape 13 to be integrated, and the middle cores 1 and 2 and the side cores 3 and 4 are fixed.

Since the central cores 5 and 6 of the middle cores 1 and 2 are connected to each other without any corners or edges, they can be directly mounted on the thin winding tape 11 without using a molded bobbin. Since the coil 12 can be formed by winding the winding, the thickness between the central core portions 5 and 6 and the coil 12 can be reduced.

Further, since the central axis has a flat shape, a large cross-sectional area can be obtained even if the thickness is thin, so that high performance can be maintained. The connection between the brim portions 7 and 9 of the middle core 1 and the side core 3 and the brim portions 8 and 1 of the middle core 2
Since no special adhesive is used to connect 0 and the side core 4, the magnetic resistance does not increase or vary.
Further, since the middle cores 1 and 2 and the side cores 3 and 4 have the same shape, the molds of the cores can be shared and can be formed at low cost.

A small transformer using the middle core of the second embodiment will be described. FIG. 3 shows a sectional view of a small transformer using the middle core of the second embodiment. The middle cores 1 and 2 of the second embodiment have the same sectional shape as the middle cores 1 and 2 of the first embodiment but are slightly different in cross section. The middle core 1 is composed of a central core portion 5 whose central axis has a semi-elliptical cross section, and brim portions 7 and 9 provided on the outer sides of the semi-elliptical shape on the long axis sides of both ends of the central core portion 5, Similarly, the middle core 2 is composed of a central core portion 6 having a semi-elliptical cross-section in the central axis, and brim portions 8 and 10 provided outside the semi-elliptical shape on the long axis sides of both ends of the central core portion 6. ing.

The method of assembling the small transformer using the middle core of the second embodiment is the same as that of using the middle core of the first embodiment. That is, the plane portions of the two inner cores 1 and 2 are aligned with each other, and the central axes of the inner cores 1 and 2 are wound and fixed by winding the tape 11 under the winding. Next, the coil 12 is formed by winding the winding wire 11 around the central core portions 5 and 6 which are formed by winding the unwinding tape 11. The side core 3 is arranged at the end of the middle core 1, and the side core 4 is arranged at the end of the middle core 2 in parallel with the central axes of the middle cores 1 and 2. Both side cores 3 and 4 are not always necessary,
Either side core 3 or 4 may be omitted and only one side core may be provided. Middle cores 1 and 2, and side cores 3 and 4
The inner cores 1 and 2 and the side cores 3 and 4 which are wound by a transformer tape 13 on the outside and are integrated are fixed.

Since the central cores 5 and 6 of the middle cores 1 and 2 are connected to each other without any corners or edges, they can be directly attached onto the thin winding tape 11 without using a molded bobbin. Since the coil 12 can be formed by winding the winding, the thickness between the central core portions 5 and 6 and the coil 12 can be reduced.

Further, since the central axis has a flat shape, a large cross-sectional area can be obtained even if the thickness is thin, so that high performance can be maintained. The connection between the brim portions 7 and 9 of the middle core 1 and the side core 3 and the brim portions 8 and 1 of the middle core 2
Since no special adhesive is used to connect 0 and the side core 4, the magnetic resistance does not increase or vary.
Further, since the middle cores 1 and 2 and the side cores 3 and 4 have the same shape, the molds of the cores can be shared and can be formed at low cost.

A small transformer using the middle core of the third embodiment will be described. In the perspective view of FIG. 4, the core of the small transformer is composed of the middle core 20 and the side core 2 of the third embodiment.
4 and 25 are provided. The middle core 20 includes a central core portion 21 whose central axis has a substantially elliptical cross section, and a central core portion 21.
Of the two ends of the brim portions 22 and 23 formed separately from each other.

The central axis of the cross section of one end of the central core portion 21 of the middle core 20 and the central axis of the brim portion 22, and the central axis of the cross section of the other end of the central core portion 21 and the central axis of the brim portion 23 are aligned. The central core portion 21 and the brim portions 22 and 2 are fixed to each other with an adhesive or the like.
After integrating 3 and 3, as shown in FIG.
Insulate by winding 6. A coil 27 is formed by winding a winding wire around the central core portion 21 of the middle core 20 around which the under winding tape 26 is wound. A side core 24 is provided at one end of the brim portion 22 and one end of the brim portion 23 of the middle core 20, and a side core 25 is provided at the other end of the brim portion 22 of the middle core 20 and the other end of the brim portion 23 as a central axis of the middle core 1. Place them in parallel. Note that both of the side cores 24 and 25 are not always necessary, and either side core 24 or 25 may be omitted, and only one side core may be provided. Medium core 2
0 cores 22 and 23, and the outside of the side cores 24 and 25 are wrapped with a transformer tape 28 to form an integrated middle core 20,
And the side cores 24 and 25 are fixed.

Since the central core portion 21 of the middle core 20 has no corners or edges, the winding is wound directly on the thin winding tape 26 without using a molded bobbin to form a coil. Since 27 can be formed, the thickness between the central core portion 21 and the coil 27 can be reduced.

Further, since the central axis has a flat shape, a large cross-sectional area can be obtained even if the thickness is thin, so that a high performance state can be maintained. Further, since the brim portions 22 and 23 and the side cores 24 and 25 of the middle core 20 have the same shape, the mold of each core can be made common and can be formed at low cost.

A small transformer using the middle core of the fourth embodiment will be described. FIG. 6 shows a sectional view of a small transformer using the middle core of the fourth embodiment. The middle core 20 of the fourth embodiment has the same shape as the middle core 20 of the third embodiment except that the cross-sectional shape is slightly different. The middle core 20 is composed of a central core portion 21 and a central core portion 21 each having a rectangular cross-sectional shape of the central axis, a semicircular shape connected to one end of the long axis, and a semicircular shape connected to the other end of the long axis. It is composed of brim portions 22 and 23 which are separately formed at both ends.

The method of assembling the small transformer using the middle core 20 of the fourth embodiment is the same as the case of using the middle core 20 of the third embodiment. The central axis of the cross section of one end of the central core portion 21 of the middle core 20 and the central axis of the brim portion 22, the central core portion 21
After the center axis of the cross section of the other end of the tape and the center axis of the brim portion 23 are aligned and fixed by an adhesive or the like to be integrated, a winding tape 26 is wound to insulate as shown in FIG. A coil 27 is formed by winding a winding wire around the central core portion 21 of the middle core 20 around which the under winding tape 26 is wound. The side cores 24 are arranged at one end of the brim portions 22 and 23 of the middle core 20, and the side cores 25 are arranged at the other ends of the brim portions 22 and 23 of the middle core 20 in parallel with the central axis of the middle core 20. . Note that both of the side cores 24 and 25 are not always necessary, and either side core 24 or 25 may be omitted, and only one side core may be provided.
The outer cores of the brims 22 and 23 and the side cores 24 and 25 are wound with a transformer tape 28 to be integrated, and the inner core 20 and the side cores 24 and 25 are fixed.

Since the central core portion 21 of the middle core 20 has no corners or edges in its cross section, the winding is wound directly on the thin winding tape 26 without using a molded bobbin to form a coil. Since 27 can be formed, the thickness between the central core portion 21 and the coil 27 can be reduced.

Further, since the central axis has a flat shape, the cross-sectional area can be wide even if the thickness is thin, so that the high performance can be maintained. Further, since the brim portions 22 and 23 and the side cores 24 and 25 of the middle core 20 have the same shape, the mold of each core can be made common and can be formed at low cost.

[0030]

As described above, according to the small transformer of the present invention, the central core portions 5 and 6 in which the inner cores 1 and 2 are integrated and the central core portion 21 of the central core 20 have different cross-sectional shapes. Since there are no corners or edges, it is not necessary to use a molded plastic bobbin, and the thickness between the core and the coil can be reduced, so the overall thickness can be reduced.

Since the central axis has a flat shape, a large cross-sectional area can be obtained and high performance can be maintained even if the thickness is reduced. Further, since the divided inner cores 1 and 2, and the brim portions 22 and 23 of the inner core 20 and the side cores 3 and 4, 24 and 25 can be formed in the same shape, the molds of the respective cores can be made common and inexpensive. A compact transformer can be realized.

[Brief description of drawings]

FIG. 1 is a perspective view of a middle core and a side core of a first embodiment constituting a small transformer of the present invention.

FIG. 2 is a cross-sectional view using a middle core of the first embodiment of the small transformer of the present invention.

FIG. 3 is a cross-sectional view using a middle core of a second embodiment of the small transformer of the present invention.

FIG. 4 is a perspective view of a middle core and a side core according to a third embodiment of the small transformer of the present invention.

FIG. 5 is a cross-sectional view using a middle core of a third embodiment of the small transformer of the present invention.

FIG. 6 is a cross-sectional view using a middle core of a fourth embodiment of the small transformer of the present invention.

FIG. 7 is a perspective view of a conventional small transformer.

FIG. 8 is a sectional view of a conventional small transformer.

[Explanation of symbols]

1, 2, 20 Medium core 5, 6, 21 Central core 7,8,9,10,22,23 Head part 3, 4, 24, 25 side core 11,26 winding tape 12, 27 coils 13,28 trans tape

Claims (4)

[Claims] 1. A central core comprising a central core portion having a substantially elliptical cross section in the central axis and a brim portion at both ends of the central core portion, a coil wound around the central core portion of the central core, and A small transformer having a side core connected to the brim portions at both ends of the middle core. 2. A middle core comprising a central core part having a rectangular cross-section of the central axis and a semi-circular shape connected to both ends of the major axis and a brim part at both ends of the central core part, and A small transformer, comprising: a coil wound around a central core portion of a middle core; and side cores connected to the brim portions at both ends of the middle core. 3. The small transformer according to claim 1, wherein a central core portion and a brim portion of the middle core are integrally formed. 4. The middle core is integrally formed in a shape that is bilaterally symmetrically cut around the minor axis portion, and the minor axis portions of the two intermediate cores are wound together to wind a coil. The small transformer according to any one of claims 1 to 3, characterized in that.