JPH09153418A - Inverter transformer - Google Patents

Abstract

It is difficult for a conventional inverter transformer for emitting light from an EL device to have a low profile while maintaining a predetermined inductance value. A core (30) made of a magnetic material, which is fixed to the upper surface of a base (10), a winding shaft (32), an upper flange (31) and a lower flange (33) integrally formed on both ends of the winding shaft (32).
And a core 50 having a through hole 51 and having the upper flange 31 of the core 30 inserted into the through hole 51 and mounted on the base 10, the lower flange 33 is provided with at least two opposing side surfaces from the upper flange 31. Is also provided with an extension portion 33a protruding laterally, and a protrusion portion 52 is formed on the lower surface of the core 50 at a position facing the extension portion 33a.
Match each other.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an inverter transformer used in an inverter for illuminating an EL (electroluminescence) element for illuminating the back surface of a liquid crystal display device, a cold cathode tube, or the like.

[0002]

2. Description of the Related Art FIG. 12 is a front view of a conventional inverter transformer, and FIG. 13 is an exploded perspective view without a coil. A terminal 2 is planted on two sides of a bobbin 1 made of an insulator, and a lead wire 3a of a coil 3 wound around a cylindrical winding shaft 1a is connected to the terminal 2
It is connected to the. Two Es in the bobbin reel 1a
The central legs 4a and 5a of the shaped cores 4 and 5 are inserted, and the core 4 and the core 5 are fixed by abutting each other.

[0003]

It is desirable that the inverter transformer for emitting light from the EL element be made as thin as possible in order not to impair the feature of the EL element that the thickness is small. However, with such a conventional transformer structure having a bobbin, it is difficult to reduce the height while maintaining a predetermined inductance value, and the height is limited to about 4 mm. An object of the present invention is to provide an inverter transformer that can be made even lower in height and smaller in size.

[0004]

SUMMARY OF THE INVENTION The present invention has a base having a plurality of terminals planted on its side surface, and a winding shaft and an upper and lower flanges integrally formed at both ends thereof. A first core made of a fixed magnetic material; and a second core made of a magnetic material that has a hole and is mounted on the base by inserting the upper flange of the first core into the hole, An extension part projecting more laterally than the upper flange is formed on at least two side faces of the lower brim of the first core, and a downward projecting part is formed on two lower surfaces of the second core facing the extension part. Is provided, and the extended portion and the protruding portion are butted against each other.

[0005]

1 to 5 show one embodiment of the inverter transformer of the present invention, in which 10 is a base made of synthetic resin. A plurality of terminals 20 are planted in the base 10, and a recess 12 having the same shape as the lower flange of the core described later is formed on the upper surface. The terminals 20 for external connection are led out to two opposite side surfaces of the base 10. As shown in FIG. 6, each terminal 20 is provided with a connecting portion 22 for connecting a coil end connected inside the base 10, and these connecting portions 22 project from the remaining two side surfaces of the base 10.

An insulative core 30 made of a magnetic material such as Ni-Zn ferrite has a winding shaft 32 and upper and lower flanges 31 and 33 integrally formed at both ends thereof. While the upper collar 31 is circular, the lower collar 33 has two opposite side surfaces extending outward to form a shape close to an ellipse. Therefore, as is clear from FIG. 5, the lower flange 33 is formed with an extension portion 33a that projects more laterally than the upper flange 31. The amount of lateral extension of the extension 33a is approximately the same as the thickness of the facing portion of the core 50, which will be described later. The core 30 is adhesively fixed to the upper surface of the base 10 so that the lower collar 33 is fitted into the recess 12 of the base 10. At this time, the core 30 is oriented so that the side without the extension 33a is the connection portion 22 side with respect to the base 10.

An inner coil 40 made of a polyurethane coated wire is wound around a winding shaft 32 of the core 30, and an outer coil 45 is further wound around the outer circumference thereof. Terminals of these coils 40, 45 and lead wires such as taps are wound around the connection portion 22 of the terminal 20 and soldered. Reference numeral 50 denotes a core made of a substantially ring-shaped magnetic body having a through hole 51 and downwardly projecting portions 52 formed at the centers of both ends. The core 50 is fixed to the core 30 by inserting the upper flange 31 of the core 30 into the through hole 51 and abutting the protrusion 52 with the extension 33a as shown in FIG.

FIGS. 7 to 11 show another embodiment of the present invention. Parts corresponding to those of the above embodiment are designated by the same reference numerals and will be described. As is apparent from FIGS. 7 and 10, the core 30 of this inverter transformer has a lower collar 33 similar to the upper collar 31 instead of extending only two opposite side surfaces of the lower collar 33 to the outside.
The lower brim 33 is formed into a circular shape, and the diameter of the lower brim 33 is made larger than the diameter of the upper brim 31 to form an extension portion 33a substantially all around the lower brim 33. On the side surface of the lower brim 33 of the core 30, there are formed a groove 34 and a shallow recess 36 that reach the vicinity of the winding shaft 32.

As shown in FIG. 10, the base 10 is provided with a plurality of terminals 20 having connection portions 22 similarly to the base of the first embodiment, and has a recess 12 into which a lower collar 33 of a core 30 can be fitted. Prepared on the upper surface. Also, on the side surface of the base 10, the groove of the core 30
A groove 14 is provided at a position corresponding to 34, and a protrusion 16 is formed at a position corresponding to a recess 36 of the core 30. That is, the core 30 is positioned with respect to the base 10 such that the groove 34 and the groove 14 are vertically overlapped with each other when the lower brim 33 is fitted into the recess 12. Therefore, the core 30 is fixed on the base 10 by inserting the lower collar 33 into the recess 12 and fitting the recess 36 into the protrusion 16 at the same time.

The lead wire 41 at the winding start end of the inner coil 40 wound around the winding shaft 32 of the core 30 is led out below the base 10 through the groove 34 and the groove 14 and then insulated from the outer coil 45. In order to increase the withstand voltage, as shown in FIG. 9, the connection portion 22 of the terminal is drawn out and soldered through the lower side of the base 10. The core 50 has a through hole 51 and a downward protruding portion 52,
The upper flange 31 of the core 30 is inserted into the through hole 51, and the protruding portion 52 is abutted on the extension portion 33a to be fixed to the core 30.

As shown in FIG. 11, the projecting portion 52 of the core 50 is formed with a notch 54 by notching the inner edge thereof. By fitting the cutout portion 54 to the end portion of the extension portion 33a, it is possible to reduce the thickness of the entire transformer while suppressing the leakage magnetic flux. It should be noted that the lower collar 33 has a recess 3
6. Instead of providing the projection 16 on the base 10, the base 10 may be recessed and the lower brim 33 may be provided with the projection. If necessary, a paste-like magnetic material in which ferrite powder and an adhesive are mixed is filled in the gap between the upper collar 31 and the core 50,
It is also possible to prevent leakage of magnetic flux in the upper part of the transformer and obtain a larger inductance.

[0012]

According to the present invention, it is possible to construct an inverter transformer having a closed magnetic circuit structure which is extremely thin and small and has a small leakage flux, and a large inductance can be obtained in spite of its small size. Using a coil wire having a diameter of 0.025 mm, an inverter transformer having a vertical and horizontal dimensions of 8 mm and a height of approximately 3 mm was prototyped, and a maximum inductance of 615 mH was obtained.

[Brief description of the drawings]

FIG. 1 is a front view showing an embodiment of a transformer according to the present invention.

FIG. 2 is a front sectional view of the transformer.

FIG. 3 is a side sectional view of the transformer.

FIG. 4 is an exploded perspective view of main parts of the transformer.

FIG. 5 is a plan view of the transformer.

FIG. 6 is a bottom view of the base.

FIG. 7 is a front sectional view showing another embodiment of the transformer of the present invention.

FIG. 8 is a plan view of the transformer.

[Fig. 9] Bottom view of the transformer

FIG. 10 is an exploded perspective view of a main part of the transformer.

[Fig. 11] Front sectional view of the core 50

[Fig. 12] Front view of a conventional inverter transformer

FIG. 13 is an exploded perspective view of the main part of the transformer.

[Explanation of symbols]

 10 Base 30 1st core 31 Upper collar 33 Lower collar 33a Extension section 50 Second core 52 Projection section

Claims (4)

[Claims] 1. A base having a plurality of terminals planted on its side surface,
A first core made of a magnetic material having a winding shaft and upper and lower flanges integrally formed at both ends thereof and having a lower flange fixed to an upper surface of a base; and a through hole having a first core in the through hole. A second core made of a magnetic material attached to the base by inserting the upper brim of the core, and projecting more laterally than the upper brim on at least two opposing side surfaces of the lower brim of the first core. An inverter transformer characterized in that an extension portion is formed, downward projections are provided at two locations on the lower surface of the second core facing the extension portion, and the extension portion and the projection portion are butted against each other. 2. The inverter according to claim 1, wherein the upper and lower flanges of the first core are both circular, and the extension of the lower flange is formed by making the diameter of the lower flange larger than the diameter of the upper flange. Trance. 3. The inverter transformer according to claim 1, wherein an inner edge of the protruding portion of the second core is cut out to form a notch, and the notch is fitted to the end of the extension of the lower collar. 4. A first groove and a second groove are formed at corresponding positions on the side surface of the base and the side surface of the lower brim of the first core, respectively, and a protrusion is formed on one of the side surface of the lower brim and the upper surface of the base. A recess is provided on the other side, the projection and the recess are fitted together, and the lead wire of the coil wound around the winding shaft of the first core is led out to the lower side of the base through the first groove and the second groove, The inverter transformer according to claim 3, wherein the terminal transformer is drawn out through the lower side of the base.