JPH10208949A - Inverter transformer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce the mounting area of an inverter transformer by respectively laying primary and secondary windings in first and second winding grooves formed around an insulating core and part of the primary winding upon the secondary winding in the second winding groove. SOLUTION: An insulating core 90 made of a magnetic material is provided with integrally molded three flanges 61, 62, and 63 and two winding grooves 64 and 65 separated from each other by the flanges 61, 62, and 63. A primary winding 70 is laid in the winding groove 64 and part 70a of the winding 70 is laid upon a secondary winding 80 laid in the groove 65. It is also possible not to lay the part 70a of the primary winding 70 which is laid upon the secondary winding 80 upon the winding 80, but below the winding 80. The core 90 having a ring-like shape is put in a through hole 92 and fixed on a base 40 by fixing the lowest flange 63 of the core 90 to the base 40.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a configuration of an inverter transformer used for an inverter for lighting a fluorescent tube such as a cold cathode discharge tube or a neon tube.

[0002]

2. Description of the Related Art FIG. 3 shows an inverter circuit for lighting a load 1 such as a fluorescent tube, which includes switching transistors 2, 3 connected in a push-pull manner, a primary winding 4, a secondary winding 5, and a feedback winding. 6 is provided with an inverter transformer 7. 8 is a bias resistor, 9 is a resonance capacitor connected in parallel to the primary winding 4, 10 is a ballast capacitor connected in series to the load 1, and an intermediate tap of the primary winding 4 is a DC power supply 12 via a choke coil 11. It is connected to the.
Then, self-excited oscillation is performed by the feedback winding 6, and the transistors 2 and 3 are alternately switched to generate a high AC voltage in the secondary winding 5. In such an inverter circuit, the output current is adjusted by weakening the electromagnetic coupling between the primary winding 4 and the secondary winding 5, and a ballast capacitor is provided.
Something that makes 10 unnecessary is considered. In that case,
Not only is the ballast capacitor 10 unnecessary, but also after the load 1 is lit, the output voltage on the secondary side of the inverter transformer 7 drops to the lit voltage of the load 1, which has the advantage of improving safety. FIG. 4 shows a conventional inverter transformer of this type. This is the core
A primary winding 4 and a secondary winding 5 are wound around 20 parallel winding shafts 21 and 22, respectively. The primary winding 4 and the secondary winding 5 are electromagnetically coupled by a pair of cores 20 and 30. The electromagnetic coupling between the primary winding 4 and the secondary winding 5 is weakened by the projection 23 of the core 20 formed between the primary winding 4 and the secondary winding 5.

[0003]

Although such an inverter transformer has the advantage that it can be made thin, it has a problem that it occupies a large area when mounted on a printed circuit board and cannot be used for a small printed circuit board. Therefore, an object of the present invention is to provide an inverter transformer having a small mounting area.

[0004]

SUMMARY OF THE INVENTION An inverter transformer according to the present invention has a first core having two winding grooves divided by a flange, and a through-hole for accommodating the first core. A second core forming a closed magnetic circuit, a primary winding, and a secondary winding are provided. The primary winding is wound around the first winding groove, and the secondary winding is wound around the second winding groove. In addition, it is characterized in that a part of the primary winding is overlapped and wound on the secondary winding of the second winding groove.

[0005]

1 and 2 show an embodiment of an inverter transformer according to the present invention, wherein reference numeral 40 denotes a base made of synthetic resin. A plurality of terminals 51 and 52 are implanted in the base 40, and a concave portion 42 for accommodating a flange at a lower end of a core described later is formed on the upper surface. A slit 44 is formed on one side surface of the base 40 for leading a lead wire of the secondary winding to the lower surface side of the base 40.

The external connection terminals 51 and 52 are base
It is led out to 40 opposite two sides. Although not shown, each of the terminals 51 and 52 includes connecting portions 51a and 52a for connecting lead wires connected inside the base 40, and these connecting portions 51a and 52a are connected to the remaining two sides of the base 40. Projecting from.

An insulating core 60 made of a magnetic material such as a Ni—Zn ferrite comprises three integrally formed flanges 61, 62,
63 and two winding grooves 6 divided by these flanges 61, 62, 63
4, 65 are provided. A slit 66 corresponding to the slit 44 of the base 40 is provided in the lower flange 63 having a diameter larger than the other flanges 61 and 62. The core 60 is bonded and fixed to the upper surface of the base 40 by aligning the position of the slit 66 with the slit 44 of the base 40 and fitting the lower end flange 63 into the concave portion 42 of the base 40.

A secondary winding 80 made of a polyurethane-coated conductor
Is wound around the winding groove 65 of the core 60, and the lead wires of both ends are wound under the base 40 through the slit 66 and the slit 44 around the connection portion 51a of the lead terminal 51 and soldered. After the primary winding 70 is wound around the winding groove 64, a part 70 a thereof is wound around the winding groove 65.
Is wound on the secondary winding 80. The secondary winding
The part 70a of the primary winding that is wound around the secondary winding 80 may be wound below the secondary winding 80 instead of above it.

[0009] Lead wires of both ends and taps of the primary winding 70 are connected to the connection portion 52a of the terminal 52. The core 90 made of a substantially ring-shaped magnetic material has a through hole 92 for accommodating the core 60, and forms a closed magnetic path together with the core 60. Core 90 is
The core 60 is fixed on the flange 63 and the base 40 at the lower end of the core 60 such that the core 60 is inserted into the through hole 92.

[0010]

According to the present invention, an inverter transformer having a small mounting area occupied on a printed circuit board can be formed, and the amount of the primary winding 70 wound on the secondary winding 80 can be adjusted to adjust the primary winding 70. There is an advantage that the magnitude of the electromagnetic coupling of the secondary winding 80 can be easily changed.

[Brief description of the drawings]

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

FIG. 2 is an exploded perspective view of the transformer without windings.

FIG. 3 is a circuit diagram illustrating an example of an inverter circuit.

FIG. 4 is a front sectional view showing a schematic configuration of a conventional inverter transformer.

[Explanation of symbols]

 61, 62, 63 Flange 64, 65 Groove 60 First core 90 Second core 70 Primary winding 80 Secondary winding

Claims (2)

[Claims] 1. A first device having two winding grooves separated by a flange.
A first core having a through-hole for accommodating the first core, a second core forming a closed magnetic circuit together with the first core, a primary winding, and a secondary winding. And a secondary winding wound around the second winding groove, and a part of the primary winding is wound around the secondary winding of the second winding groove. Inverter transformer. 2. The method according to claim 1, further comprising a base having a plurality of terminals planted on a side surface and a recess formed on an upper surface, wherein a lower end flange of a first core having a plurality of flanges is fitted and fixed in the recess. Inverter transformer.