JPH077120U - Step-up transformer - Google Patents

Abstract

(57) [Summary] (Correction) [Constitution] Bobbin 10 having cylindrical winding shaft 12 with terminals planted on two sides and protruding upward, and primary winding on low voltage side wound around winding shaft 12. The wire 30 and the secondary winding 50 on the high voltage side, which is wound in multiple layers from the inside to the outside and is electromagnetically coupled to the primary winding 30.
And a pair of cores 60, 70 that are butted up and down,
Connect the lead wires of the primary winding 30 and the secondary winding 50 to the bobbin 10
In the step-up transformer connected to terminals on different sides of
While installing the insulating sheet 40 between the secondary winding 50 and the lower core 70, a cutout 71 is provided on one side surface of the core 70, and the winding start of the secondary winding 50 pulled out below the sheet 40 The lead wire is led out in the terminal direction through the notch 71 of the core 70, and the lead wire in the notch 71 is covered with the insulating resin 80 applied to the sheet 40. [Effect] Lead wire of the winding start of the secondary winding 50 and the secondary winding 50
Corona discharge does not occur between the other parts and the withstand voltage is improved.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to a structure of a small and thin step-up transformer suitable for use as an inverter for lighting a cold cathode tube for backlighting a liquid crystal display device.

[0002]

[Prior Art and Problems to be Solved by the Invention]

 The applicant previously proposed, in Japanese Patent Application No. 4-299232, a low-profile and efficient step-up transformer having a configuration in which secondary windings on the high voltage side are aligned and wound in multiple layers. The present invention relates to an improvement of this type of step-up transformer, and its purpose is to increase the withstand voltage.

[0003]

[Means for Solving the Problems]

 The step-up transformer of the present invention comprises an insulating bobbin having a cylindrical winding shaft which is provided with terminals on two opposite side surfaces and protrudes upward, a low-voltage side primary winding wound around the winding shaft, and an inner side. It has a secondary winding on the high voltage side, which is wound in multiple layers from the outside toward the outside and electromagnetically coupled to the primary winding, and a pair of cores that are butted against each other. In a step-up transformer in which the wires are connected to terminals on different sides of the bobbin, an insulating sheet is installed between the secondary winding and the lower core, and a cutout is provided on one side of the lower core. The structure is characterized in that the lead wire at the beginning of the secondary winding that is pulled out downward is led out in the direction of the terminal through the core notch, and this lead wire in the notch is covered with an insulating resin applied to the sheet. To do.

[0004]

【Example】

 1 shows a step-up transformer according to an embodiment of the present invention. FIG. 1 is a bottom view, FIG. 2 is a bottom view during assembly, FIG. 3 is an exploded perspective view, and FIG. 4 is a front sectional view. The bobbin 10 made of plastic has a plurality of terminals 21, 22, 23 planted on two opposite side surfaces, a cylindrical winding shaft 12 protruding upward from the center, and a collar 13 at the upper end of the winding shaft 12. It is provided. The terminal provided on one side of the bobbin 10 is divided into a lead wire connection terminal 23 of the secondary winding 50 and an external connection terminal 22. The terminal 22 and the short terminal 23 are paired one by one. That is, the bobbin 10 is integrally connected inside.

As is apparent from FIG. 4, a low-voltage side primary winding 30 is wound around the winding shaft 12 of the bobbin 10, and a high-voltage side secondary winding 50 is attached to the lower surface of the bobbin 10. . The secondary winding 50 located below the bobbin 10 is electromagnetically coupled to the opposing primary winding 30 via the bobbin 10. Like the winding on the high voltage side of the step-up transformer of Japanese Patent Application No. 4-299232, the secondary winding 50 is formed by winding the wire rods in multiple layers from the inner side to the outer side, thereby reducing the potential difference between the overlapping wire rods. It has been rolled and packed. The low-voltage side primary winding 30 is wound in a normal manner without any special winding, and its lead wire 31 is passed over the bobbin 10 and is connected to the terminal 21 mounted on one side of the bobbin 10. .

Reference numerals 60 and 70 are cores made of a non-conductive magnetic material. The pair of magnetic cores 60 and 70 sandwich the bobbin 10 from above and below and are abutted against each other to form a closed magnetic path. The upper core 60 has an E-shaped cross section having a flat plate portion 61, outer legs 62 integrally formed at both ends thereof, and a cylindrical central leg 63 integrally formed at the center of the flat plate portion 61. 63 is inserted in the hollow part of the winding shaft 12. The center leg 63 is slightly shorter than the outer leg 62 so that a gap is formed between the center leg 63 and the abutted core 70 to prevent magnetic saturation. On the other hand, the core 70 attached to the lower side of the bobbin 10 has a flat plate shape as a whole, and one side surface thereof is provided with a triangular notch 71. Then, between the secondary winding 50 and the lower core 70, an insulating sheet 40 having a notch 41 cut in from one side is provided in the center.

As shown in FIG. 2, the winding start side lead wire 51 a of the secondary winding 50 is drawn from the tip end of the cutout portion 41 of the sheet 40 to the lower surface of the sheet 40 and is formed in the groove 15 formed on the lower surface of the bobbin 10. It is connected to the terminal 23 through. The lead wire 51a of the portion passing below the seat 40 is located in the notch 71 of the lower core 70 as shown in FIG. The lead wire 51a in the notch 71 is covered with an insulating resin 80 such as an epoxy adhesive applied to the sheet 40. The lead wire 51b on the winding end side is pulled out from the top of the sheet 40 and connected to another terminal 23.

In the secondary winding 50, the potential difference between the lead wire 51a on the winding start side and the other portion increases as it approaches the winding end portion on the outer side. When an output voltage of, for example, 1000 Vrms is taken out from the secondary winding 50 side, a very strong electric field of about 20 to 27 kV / mm is generated around the lead wire 51a on the winding start side. The value of this electric field greatly exceeds the dielectric strength of air. However, in this step-up transformer, as shown in the enlarged view of FIG. 5, not only the sheet 40 is interposed between the outer portion 50a of the secondary winding 50 and the lead wire 51a, but also the lead wire 51a is applied to the sheet 40. Since the space between the sheet 40 and the lead wire 51a is covered with the resin 80, the lead wire 51a on the winding start side approaches the outer portion 50a of the secondary winding 50 having a large potential difference. There is no risk of dielectric breakdown due to corona discharge. On the other hand, the electric field strength between the sheet 40 and the secondary winding 50 is about ⅕ of the electric field strength in the vicinity of the lead wire 51a, so that a sufficient breakdown voltage can be secured without applying the resin 80 in particular. . The work of applying the resin 80 to the sheet 40 and the lead wire 51a can be easily performed with good workability because the notch 71 is provided in the core 70.

It should be noted that the insulating sheet 40 may be partially inserted into the abutting portion of the core 60 and the core 70, and may also be used for adjusting the gap between the core 60 and the core 70. Further, instead of the non-conductive magnetic material cores 60 and 70, a conductive magnetic material core whose surface is covered with an insulator may be used. The flat core 70 and the E-shaped core 60 may be interchanged in position so that a cutout is provided on the E-shaped core 60 side. The present invention is not limited to a transformer having primary windings and secondary windings arranged in an upward and downward direction as long as it is a transformer having secondary windings wound in multiple layers from the inside to the outside. It can also be applied to a boosting transformer in which a secondary winding is wound around the side surface of the.

[0010]

EFFECTS OF THE INVENTION According to the present invention, the lead wire at the beginning of the secondary winding can be easily covered with an insulating resin, and a corona discharge may occur between the lead wire and the outer winding portion. It is possible to obtain a step-up transformer with high insulation withstand voltage.

[Brief description of drawings]

FIG. 1 is a bottom view showing an embodiment of the transformer of the present invention.

FIG. 2 is a bottom view of the transformer during assembly.

FIG. 3 is an exploded perspective view showing a part of the transformer by cutting away.

FIG. 4 is a front sectional view of the transformer.

5 is a cross-sectional view of the main part taken along the line AA of FIG.

[Explanation of symbols]

 10 bobbin 12 winding shaft 21,22,23 terminal 30 primary winding 40 seat 41 notch 50 secondary winding 51 lead wire 60/70 core 71 notch 80 insulating resin

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Shoichi Utsuki 18 Gomigaya, Tsurugashima City, Saitama Prefecture Toko Co., Ltd. Saitama Office

Claims (2)

[Scope of utility model registration request] 1. An insulative bobbin having a cylindrical winding shaft in which terminals are planted on opposite two side surfaces and protruding upward, a low-voltage side primary winding wound around the winding shaft, and from inside. It has a secondary winding on the high-voltage side that is wound in multiple layers toward the outside and electromagnetically coupled to the primary winding, and a pair of cores that are butted against each other.The lead wires of the primary winding and the secondary winding are respectively In a step-up transformer connected to terminals on different sides of a bobbin, an insulating sheet is installed between the secondary winding and the lower core, and a cutout is provided on one side surface of the lower core. The lead wire at the beginning of winding of the secondary winding drawn out to the above is led out in the terminal direction through the notch of the core, and the lead wire in the notch is covered with an insulating resin applied to a sheet. Boost transformer to do. 2. A pair of cores having a central leg at the center and outer legs at both ends, a first core having an E-shaped cross section and a second flat plate.
Of the secondary winding, the outer leg is positioned on the two opposite side surfaces on the side where the bobbin terminal is not provided, and the central leg is inserted into the bobbin winding shaft from above. 2. The step-up transformer according to claim 1, wherein the second core arranged below is abutted against each other and the notch is provided in the second core.