JPH10275729A - Inverter transformer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an inverter transformer wherein a dielectric strength between primary and secondary coils is assured, with lower height configuration. SOLUTION: An inverter transformer is provided with a first core 30 wherein an upper flange 31 and a lower flange 33 are formed as one body on both ends of a winding axis 32 and the lower flange 33 is larger than the upper 31 in diameter, an almost ring-shaped second core 60 wherein a through hole 61 is provided and the upper flange 31 of the first core 30 is inserted into the through hole 61 to be batted to the lower flange 33, a secondary coil 2 wound around a winding axis 32 of the first core 30, and a ring-like primary coil 1 which comprises a hole to house the secondary coil 2 at its center. The primary coil 1 is fixed on the lower flange 33 of the first core 30 at a specified interval from the secondary coil 2.

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 flat fluorescent lamp or the like for a digital electronic still camera.

[0002]

2. Description of the Related Art An inverter circuit of this type applies a pulse voltage to a primary winding and turns on a flat fluorescent lamp or the like by an AC voltage excited to a secondary winding. Since this inverter circuit is used in a floating state without grounding the secondary side, it is necessary to increase the withstand voltage between the primary winding and the secondary winding. Conventionally, as shown in FIG. 5, a primary winding 1 and a secondary winding 2 are arranged in a vertical direction, and an insulating bobbin 3 is interposed between them to secure a withstand voltage. Then, there was a problem that it was difficult to reduce the height. In FIG. 5, reference numerals 4 and 5 denote E-shaped and I-shaped cores, respectively.

On the other hand, a thin inverter transformer as shown in FIG. 6 is also used for an inverter circuit for lighting a straight fluorescent lamp or a neon tube. This is the primary winding 1
And the secondary winding 2 is wound around the winding shaft 6a of the drum-shaped core 6, and there is an advantage that the height can be reduced. In FIG. 6, 7 is a ring-shaped core, and 8 is an insulating base.

[0004]

However, the structure shown in FIG. 6 is effective when one end of the secondary winding is grounded, but has a problem that the withstand voltage cannot be secured when used in a floating state. SUMMARY OF THE INVENTION It is an object of the present invention to provide an inverter transformer that can ensure a withstand voltage between a primary winding and a secondary winding and can be configured to have a low profile.

[0005]

According to the present invention, an upper flange 31 and a lower flange 33 are integrally formed at both ends of a winding shaft 32, and the lower flange 33 is an upper flange.
A first core 30 having a diameter larger than that of the first core 31; And a secondary winding 2 wound around a winding shaft 32 of the first core 30, and a ring-shaped primary winding 1 having a hole for accommodating the secondary winding 2 in the center. The inverter transformer is characterized in that the primary winding 1 is fixed on the lower flange 33 of the first core 30 at a predetermined distance from the secondary winding 2.

[0006]

1 and 2 show an embodiment of an inverter transformer according to the present invention, in which reference numeral 10 denotes a base made of synthetic resin. A plurality of terminals 21 and 22 are implanted in the base 10, and a concave portion 12 for accommodating a flange at a lower end of the core 30 is formed on an upper surface. The terminals 21 and 22 are respectively led to two opposite side surfaces of the base 10. The insulating core 30 made of a magnetic material such as a Ni-Zn-based ferrite includes a circular upper flange 31 and a lower flange 33 integrally formed at both ends of the winding shaft 32, and the lower flange 33 is formed from the upper flange 31. Are also molded to a large diameter. Core 30 is
The lower flange 33 is fitted into the concave portion 12 of the base 10 to
Adhesively fixed to the upper surface of the device.

Secondary winding 2 made of polyurethane-coated conductor
Is wound around the winding shaft 32 of the core 30, and the lead wires of both ends are connected to the terminal 22.
Connected to Reference numeral 40 denotes a substantially cylindrical ring made of an insulator. The ring 40 is incorporated so that the upper flange 31 of the core 30 is inserted into the through hole 41, and is adhesively fixed to the lower flange 33. An air gap 50 is formed between the ring 40 and the secondary winding 2. The cross section of the ring 40 is L-shaped, and the primary winding 1 is wound around a winding groove formed by the ring 40 and the lower flange 33. Lead wires such as both terminals and taps of the primary winding 1 are connected to the terminal 21.

The core 60 made of a substantially ring-shaped magnetic material is abutted against the lower flange 33 of the core 30 to form a closed magnetic path together with the core 30. The core 60 is formed by inserting the upper flange 31 of the core 30, the ring 40, the primary winding 1, and the like into the through hole 51, and
It is fixed on the lower collar 33 and the base 10. In the inverter transformer configured as described above, the primary winding 1 and the secondary winding 2 are separated from each other by the gap 50 and the thickness of the ring 40. The magnitude of the electromagnetic coupling between the primary winding 1 and the secondary winding 2 is determined by setting the wire diameter of the secondary winding 2 to, for example, 0.025 mm to 0.
It is adjusted by changing the size of the gap 50 by selecting from the range of 05 mm.

FIG. 3 shows another embodiment of the present invention.
Secondary winding 2 and primary winding 1 without using insulator ring 40
In this configuration, only the gap 50 is formed. In this case, the primary winding 1 is fixed to the lower collar 33 in a state of being previously wound into a ring shape. Such a primary winding 1 is, for example, a so-called self-fusing wire in which a thermoplastic fusible varnish or the like is covered on the outside of a copper wire coated with polyurethane, and this wire is heated or a solvent is applied. After winding while
It is obtained by cooling or drying. In addition, as shown in FIG. 4, the gap between the secondary winding 2 and the primary winding 1 and the gap between the core 30 and the core 50 may be filled with an insulating adhesive 70.

[0010]

According to the present invention, a low-profile inverter transformer having a height of 2 to 3 mm can be easily realized, and a sufficient withstand voltage can be ensured. When a transformer having the structure shown in FIG. 3 was fabricated and measured, the dielectric strength was 1.6 KVrms in the conventional structure and 2.3 KVrm in the conventional structure.
s and about 40% improvement.

[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 a plan view of the transformer.

FIG. 3 is a front sectional view showing another embodiment of the present invention.

FIG. 4 is a front sectional view showing still another embodiment of the present invention.

FIG. 5 is a front sectional view showing a first conventional example.

FIG. 6 is a front sectional view showing a second conventional example.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Primary winding 2 Secondary winding 30 1st core 31 Upper flange 32 Winding shaft 33 Lower flange 60 2nd core

Claims (3)

[Claims] 1. A first core having an upper flange and a lower flange integrally formed at both ends of a winding shaft and a lower flange having a larger diameter than the upper flange, a first core having a through hole, and a first core having a through hole. An upper ring of the first core is inserted and a substantially ring-shaped second core butted against a lower flange, a secondary winding wound around a winding shaft of the first core, and a secondary winding in the center. An inverter transformer comprising a ring-shaped primary winding having a hole for accommodating therein, wherein the primary winding is fixed on a lower flange of the first core at a predetermined distance from the secondary winding. Trance. 2. The method according to claim 1, wherein a substantially cylindrical ring made of an insulator is fitted between the secondary winding and the primary winding, and a gap is formed between the ring and the secondary winding. Inverter transformer. 3. The inverter transformer according to claim 1, wherein the primary winding pre-wound in a ring shape is fixed to the lower flange, and a gap is formed between the secondary winding and the primary winding.