JPH0672228U - Step-up transformer - Google Patents

Abstract

(57) [Abstract] [Purpose] To improve the withstand voltage and facilitate the extraction of the lead wire 51a of the secondary winding 50. [Structure] A low-voltage-side primary winding 30, a high-voltage-side secondary winding 50 aligned in multiple layers from inside to outside and electromagnetically coupled to the primary winding 30, and a pair of magnetic cores butted against each other. In a step-up transformer including an insulating sheet 80 adjacent to the secondary winding 50 and inserted between a pair of cores, a thick portion 81 having a larger thickness at one end portion of the insulating sheet 80 than other portions. Then, the thick portion 81 is interposed between the one lead wire 51a of the secondary winding 50 and the secondary winding 50.

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]

 According to Japanese Patent Application No. 4-304887, the applicant previously improved the efficiency with a low profile by arranging the secondary winding on the high-voltage side in multiple layers in series, and at the same time improved the insulation withstand voltage by using an insulating sheet. I proposed a boost transformer. The present invention relates to an improvement of this type of step-up transformer.

[0003]

[Problems to be solved by the device]

 The insulating sheet shown in the embodiment of Japanese Patent Application No. 4-304887 is as shown by reference numeral 40 in FIG. This insulating sheet 40 has a circular through hole 41 in the center, and is provided in the vicinity of the slit 42 reaching the through hole 41 from one side and the inner peripheral surface 55 of the secondary winding 50 on the high voltage side. It has a small cutout 45. Then, the lead wire 51a at the beginning of the winding of the secondary winding 50 is drawn out from the cutout portion 45 to below the seat 40, and the seat 40 is interposed between the lead wire 51a and the main body of the secondary winding 50 to increase the withstand voltage. It has a different structure. The thickness of the sheet 40 that determines the distance between the pair of cores is generally selected from the range of 50 to 500 μm according to the required characteristics of the step-up transformer. When the thickness of the sheet 40 is 200 μm or more, a sufficient withstand voltage can be usually obtained, but when the thin sheet 40 of about 50 to 60 μm is used, the insulation between the lead wire 51a and the secondary winding 50 is not sufficient. This is sufficient, and there is a problem that corona discharge is generated and dielectric breakdown easily occurs. Further, since the lead wire 51a inside the secondary winding 50 has to be pulled out through the cutout portion 45, there is a drawback that it is troublesome to lead out the lead wire 51a during assembly. Therefore, an object of the present invention is to further increase the withstand voltage and to improve the work efficiency of the process of drawing out the lead wire 51a of the secondary winding 50.

[0004]

[Means for Solving the Problems]

 In the step-up transformer of the present invention, a thicker part is formed at one end of the insulating sheet, which is thicker than the other part, and this thickness is provided between one lead wire of the secondary winding and the main body of the secondary winding. It is characterized by the interposition of parts. Further, the present invention is characterized in that a cutout portion reaching the thick portion from the other end portion is formed in the insulating sheet.

[0005]

【Example】

 1 and 2 show an embodiment of a step-up transformer according to the present invention. FIG. 1 is a bottom view showing a lower core 70 removed, and FIG. 2 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 terminals 22 and 23 provided on one side surface of the bobbin 10 are divided into those for connecting the lead wire of the secondary winding 50 and those for external connection. That is, the terminal 22 and the short terminal 23 are paired one by one and are integrally connected inside the bobbin 10.

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. 4-304887, the secondary winding 50 is formed by winding the wire rods in multiple layers from the inside to the outside to reduce 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 connected to a terminal 21 mounted on one side of the bobbin 10. is there.

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 in the center of the flat plate portion 61. 63 is inserted in the hollow portion of the winding shaft 12. On the other hand, the core 70 attached to the lower side of the bobbin 10 has a flat plate shape. A thin insulating sheet 80, which is interposed between the outer leg of the core 60 and the core 70 to prevent magnetic saturation, is inserted between the core 60 and the core 70. As shown in FIGS. 3 and 4, a thick portion 81 having a larger thickness than other portions is formed at one end of the sheet 80. To form the thick portion 81, another thick insulating sheet may be stacked on the sheet 80 and adhered thereto, or an adhesive may be applied. The thickness of the sheet 80 is, for example, 60 μm in the thin portion and 200 μm in the thick portion 81. Further, the seat 80 is provided with a notch 82 removed from the other end to a portion facing the central leg 63 of the core. The tip of the cutout portion 82 reaches the end edge of the thick portion 81. Notches 83 are provided at the four corners of the sheet 80 so that the two cores 60 and 70 can be bonded at this position.

In the secondary winding 50, the potential difference between the lead wire 51a on the winding start side and the other portion becomes larger as it approaches the winding end portion on the outer side. Therefore, the lead wire 51a on the winding start side is drawn out to the bottom of the sheet 80 through the notch 82 so as not to cause dielectric breakdown by approaching the winding end portion having a large potential difference, and as shown in the bottom view of FIG. It passes under the thick portion 81, passes through the groove 15 on the lower surface of the bobbin 10, and is connected to the terminal 23. Therefore, the thick portion 81 of the sheet 80 is interposed between the winding wire 51a on the winding start side of the secondary winding 50 and the secondary winding 50. On the other hand, the lead wire 51b on the winding end side is drawn out from above the sheet 80 and is connected to another terminal 23 through the groove 15. It should be noted that the present invention is not limited to the transformer of the embodiment, but may be inserted in a step-up transformer in which a secondary winding is wound concentrically on the side surface of the primary winding, or a winding shaft portion of the primary winding and the secondary winding. It can also be applied to a step-up transformer or the like in which two protrusions are provided on one core and the primary winding and the secondary winding are arranged side by side.

[0009]

[Effect of device]

 According to the present invention, even if the insulating sheet is thin, the thick portion is interposed between the one lead wire of the secondary winding and the secondary winding. A step-up transformer having a withstand voltage can be easily constructed. Also, by forming a cutout in the insulating sheet that reaches the thickened portion from the end on the side opposite to the thickened portion, the lead wire inside the secondary winding is pulled out from the cutout to under the insulating sheet during assembly. It has the effect of simplifying work and improving productivity.

[Brief description of drawings]

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

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

[Fig. 3] Bottom view of insulating sheet

FIG. 4 is a front view of an insulating sheet.

FIG. 5 is a bottom view of a transformer main part showing a conventional example.

[Explanation of symbols]

 30 Primary winding 50 Secondary winding 51 Lead wire 60/70 Core 80 Insulation sheet 81 Thick section 82 Notch section

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Shoichi Utsugi 18 Omigamiya, Tsurugashima City, Saitama Prefecture Toko Co., Ltd. Saitama Business Office (72) Asahi Hiura 18 Gomigaya, Tsurugajima City, Saitama Prefecture Toko Co., Ltd. Saitama Office

Claims (2)

[Scope of utility model registration request] 1. A low-voltage-side primary winding, a high-voltage-side secondary winding that is aligned and wound in multiple layers from the inner side to the outer side and electromagnetically coupled to the primary winding, and a pair of magnetic cores butted against each other. In a step-up transformer having an insulating sheet adjacent to the secondary winding and inserted between the pair of cores, a thick portion thicker than other portions is formed at one end of the insulating sheet, A step-up transformer, wherein the thick portion is located between one of the lead wires of the secondary winding and the secondary winding. 2. The step-up transformer according to claim 1, wherein the insulating sheet is formed with a notch reaching from the other end to the thick portion.