JP2000021656A - Inverter transformer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce the height of a transformer which has large dielectric strength between its primary and secondary winding. SOLUTION: This inverter transformer is equipped with an insulating bobbin 10, having a base part 11 where a terminal is implanted, a center 12 projecting upwards from the base part 11, and a partition wall 13 positioned concentrically outside the center 12, a T-sectioned core 50 provided with a projection part 52 at a flat plate part 51, a U-sectioned core 60 which forms a closed magnetic path by being abutted against the core 50, a secondary winding 30 wound around the roll 12, and a primary winding 40 positioned outside the secondary winding 30 across the partition wall 13. Then the projection part 52 of the core 50 is inserted into the hole of the center 12 of the bobbin, and the primary winding 40 and secondary winding 30 are positioned facing directly opposite the flat plate part 51 of the core 50.

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 a DC / AC inverter for lighting a cold cathode ray tube or the like for illuminating a back surface of a liquid crystal display device.

[0002]

2. Description of the Related Art In the case of an inverter circuit for lighting a flat-type cold cathode lamp, a secondary circuit of an inverter transformer is used in a floating state without grounding in order to prevent luminance unevenness from occurring. Therefore, a high voltage of 1.5 to 2.5 kV is applied alternately to both ends of the secondary winding of the inverter transformer, and it is necessary to increase the dielectric strength between the primary winding and the secondary winding. .

FIG. 5 shows a conventional inverter transformer having a large withstand voltage between a primary winding and a secondary winding. A primary winding 3 is wound around a cylindrical winding shaft 2 a of an insulating bobbin 2 to which a terminal 1 is attached, and a secondary winding 4 is attached below the bobbin 2. A pair of magnetic cores 5 and 6 have a structure in which the bobbin 2 is sandwiched from above and below with an insulating sheet 7 therebetween to form a closed magnetic circuit.

[0004]

Since the inverter transformer can be mounted in a narrow space of a portable device such as a digital electronic still camera or an 8 mm video camera, it must be formed thin. However, since the conventional inverter transformer shown in FIG. 4 has a structure in which the primary winding 3 and the secondary winding 4 are arranged in the height direction, it is difficult to reduce the thickness. SUMMARY OF THE INVENTION It is an object of the present invention to provide an inverter transformer that can be reduced in height and can increase the withstand voltage between the primary winding and the secondary winding.

[0005]

SUMMARY OF THE INVENTION The present invention provides a base portion having terminals planted on two opposite side surfaces, a cylindrical winding shaft projecting upward from the base portion, and a concentric circle formed outside the winding shaft. An insulating bobbin having a cylindrical bulkhead located thereon, and a T-shaped insulating section having a downwardly projecting portion at the center of the flat plate portion and inserting the projecting portion into a hole passing through the bobbin winding shaft. A first core made of a magnetic material, a second core made of a magnetic material having a U-shaped cross section which is formed in contact with the first core to form a closed magnetic circuit, and a secondary core wound around a bobbin winding shaft. It is characterized by comprising a winding and a primary winding located outside the secondary winding via a partition, wherein the primary winding and the secondary winding are directly opposed to the flat plate portion of the first core. .

[0006]

1 and 2 show an embodiment of an inverter transformer according to the present invention. Reference numeral 10 denotes a base unit 11, a cylindrical winding shaft 12, and a cylindrical partition wall 13, which are integrally formed of synthetic resin. Bobbin. As shown in FIG. 3, terminals 21 and 22 and a terminal 23 are attached to two opposing side surfaces of the base portion 11, respectively. A winding shaft 12 having a hole 14 penetrating the center protrudes upward from the center of the base portion 11, and a cylindrical partition wall 13 is provided outside the winding shaft 12 concentrically with the winding shaft 12. The bobbin 10 extends from one side of the base 11 to the winding shaft 12 and has a partition 13.
A slit 15 (FIGS. 2 and 3) for cutting a part of the vertical portion is formed.

[0007] A secondary winding 30 is wound around the winding shaft 12, and its lead wire 31 is drawn out to the lower surface of the base portion 11 through the slit 15 and then connected to the terminal 21. The terminals 21 and 22 provided on one side surface of the base 11 are connected to the secondary windings as apparent from FIG.
30 are divided into a lead wire connection terminal 21 and an external connection terminal 22. That is, the terminal 22 and the short terminal 21 are paired one by one, and are integrally connected inside the base portion 11. A primary winding 40 is wound around the outside of the secondary winding 30 via a partition 13, and a lead wire (not shown) is connected to a terminal 23 attached to the other side surface of the base portion 11.
Although not shown, after attaching the secondary winding 30 to the bobbin 10 and connecting the lead wire 31 to the terminal 21, the slit 15 in the partition 13 is sealed with an insulator such as an adhesive.

Reference numeral 50 denotes a T-shaped core having a columnar projecting portion 52 at the center of the flat plate portion 51, and 60 denotes a flat plate portion.
A core having a U-shaped cross section having legs 62 extending upward at both ends of 61. The core 50 is formed of a highly insulating Ni-Zn ferrite material. Core 60 is the same Ni-Z as core 50
An n-based ferrite material may be used, but it is preferable to use an Mn-Zn-based ferrite material in order to further increase the saturation magnetic flux density and reduce the core loss. The core 50 has a protrusion 52
Is inserted into the hole 14 of the winding shaft 12, and the flat plate portion 51 is abutted against the leg portion 62 of the core 60 to form a closed magnetic path.
The upper surfaces of the primary winding 40 and the secondary winding 30 directly face the flat plate portion 51 of the core 50.

As a method of winding the secondary winding 30 around the winding shaft 12, instead of directly winding the secondary winding 30 around the winding shaft 12, the secondary winding 30 pre-wound and wound around the winding shaft 12 of the bobbin 10 and the partition wall. It is performed by inserting from above between 13. On the other hand, to wind the primary winding 40 outside the partition wall 13, the core 50 and the bobbin 10 are united,
After forming a winding groove sandwiched between the flat plate portion 51 and the base portion 11, winding is performed on the bobbin 10 or, similarly to the secondary winding 30, a primary winding 40 pre-wound and hardened on the base portion 11. It should just be placed.

It is to be noted that, instead of the slit 15 extending by cutting the partition wall 13 from the side surface of the base portion 11, as shown in FIG.
A slit 16 may be formed in the bobbin 10 so as to vertically penetrate only the base portion 11 between the bobbin 10 and the partition 13. In this case, the workability of pulling out the lead wire 31 to the lower side of the base portion 11 becomes worse, but it is not necessary to close the partition wall 13 later.

[0011]

According to the present invention, the use of a bobbin having no upper flange on the winding shaft enables a further reduction in height, and furthermore, the primary winding and the secondary winding are separated by a partition, so that insulation is achieved. An inverter transformer with a large withstand voltage can be obtained.

[Brief description of the drawings]

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

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

FIG. 3 is a plan view of a bobbin.

FIG. 4 is a front sectional view showing another embodiment of the bobbin.

FIG. 5 is a front sectional view showing a conventional example of an inverter transformer.

[Explanation of symbols]

 10 bobbin 11 base 12 winding shaft 13 partition 15 slit 30 secondary winding 40 primary winding 50 first core 60 second core

Claims (2)

[Claims] 1. A base portion having terminals implanted on two opposing side surfaces, a cylindrical winding shaft projecting upward from the base portion, and a cylindrical partition wall concentrically located outside the winding shaft. A first insulating bobbin having an insulating bobbin having a downwardly projecting portion at the center of the flat plate portion and having the projecting portion inserted into a hole passing through a bobbin winding shaft; , A second core made of a magnetic material having a U-shaped cross section that forms a closed magnetic path by being brought into contact with the first core, a secondary winding wound around a bobbin winding shaft, and a partition wall. An inverter transformer, comprising: a primary winding positioned outside a secondary winding, wherein the primary winding and the secondary winding are directly opposed to a flat plate portion of the first core. 2. A slit that extends from one side surface of the base portion to the vicinity of the winding shaft and vertically cuts a part of the cylindrical partition wall. After the secondary winding is mounted on the bobbin, the slit of the partition wall portion is removed. The inverter transformer according to claim 1, wherein the inverter transformer is sealed with an insulator.