JP2012099590A - Transformer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a transformer with a sufficiently small size.SOLUTION: A primary winding 51 is wound around a first section 21A in such a manner that it does not protrude from partition plates 22 and 23 in the vertical direction or in the front-rear direction. A first secondary winding 52 and a second secondary winding 53 are wound around a third section 21C in such a manner that they do not protrude from the partition plates 22 and 23 in the vertical direction or in the front-rear direction. An auxiliary winding 54 is made of a triple-layer insulated wire and is wound around a second section 21B in such a manner that it does not protrude from the partition plates 22 and 23 in the vertical direction or in the front-rear direction. One end and the other end of the auxiliary winding 54 are passed through a lead-out groove of the partition plate 22 and lead out toward a terminal block 31 while facing an end of a bottom wall 21D in a direction perpendicular to an axial direction of a substantially cylindrical part 21. A plate rib 40B of a case 40 is inserted in a groove-shaped portion between the partition plates 22 and 23.

Description

  The present invention relates to a transformer, and in particular, a peripheral surface of a substantially cylindrical portion of a bobbin is partitioned into a plurality of sections in the axial direction of the substantially cylindrical portion, and a primary winding and a secondary winding are wound around separate sections. Regarding transformers.

  2. Description of the Related Art Conventionally, a power supply transformer having a configuration in which a primary winding and a secondary winding are wound around a bobbin is known. The bobbin has a substantially cylindrical portion, and the circumferential surface of the substantially cylindrical portion is partitioned into a plurality of sections by a partition plate in the axial direction of the substantially cylindrical portion. Each section is wound with a primary winding and a secondary winding. In the axial direction of the substantially cylindrical portion, the partition plate has a predetermined thickness, so that the primary winding and the secondary winding are wound. The windings are separated by a predetermined distance and meet safety standards. Such a transformer is described in, for example, Japanese Utility Model Laid-Open No. 5-48313 (Patent Document 1).

Japanese Utility Model Publication No. 5-48313

  In recent years, electronic components such as transformers are required to be further downsized. However, the above-described conventional transformer has not been sufficiently downsized.

  Therefore, an object of the present invention is to provide a transformer that is sufficiently miniaturized.

  In order to achieve the above object, the present invention includes a first section including a substantially cylindrical portion made of an insulating material, and an outer peripheral surface of the substantially cylindrical portion arranged adjacent to the axial direction of the substantially cylindrical portion. A bobbin having two sections and a third section, a terminal electrode provided on the bobbin, an insertion part inserted into a space defined by the inner peripheral surface of the substantially cylindrical part, and the cylindrical part are surrounded. A core having an enclosing portion, a primary winding formed of a conductive wire covered with an insulating coating, wound around the first section, and having one end and the other end electrically connected to the terminal electrode; and an insulating coating A secondary winding comprising a conducting wire covered with a coil, wound around the third section and having one end and the other end electrically connected to the terminal electrode, and the primary winding and the secondary winding. The second section comprising a conductive wire covered with an insulating coating having a higher insulating property than the insulating coating. A high-insulation winding wound around the boundary between the first section and the second section, and the boundary between the second section and the three sections. A partition plate extending in a direction is provided, and the first section and the second section are partitioned by the partition plate, and the second section and the three sections are partitioned by the partition plate, thereby The second section has a groove shape, and is disposed between the convex portion that engages with the groove-shaped second section, the primary winding, the secondary winding, and the high-insulation winding and the core. There is provided a transformer including a case having a case main body portion.

  A primary winding composed of a conductive wire covered with an insulating coating and wound around a first section and electrically connected at one end and the other end to a terminal electrode, and a third section consisting of a conductive wire covered with an insulating coating And a secondary winding whose one end and the other end are electrically connected to the terminal electrode, and a primary winding and an insulating coating having a higher insulating property than the insulating coating of the secondary winding. In order to provide a high-insulation winding made of a conductive wire and wound around the second section, a portion that has conventionally become a dead space for separating the primary winding and the secondary winding by a predetermined distance, It can be effectively used as a space for winding a highly insulated winding.

  In addition, partition plates extending in the circumferential direction of the substantially cylindrical portion are respectively erected at the boundary between the first section and the second section and between the second section and the third section. And the second section are partitioned by a partition plate, and the second section and the third section are partitioned by the partition plate, whereby the second section has a groove shape, and a convex portion that engages with the groove-shaped second section; Creepage distance between primary and secondary windings to provide a case having a primary winding, a secondary winding, and a case body portion disposed between a highly insulated winding and a core Can be secured longer. For this reason, the distance between the primary winding and the secondary winding in the axial direction of the substantially cylindrical portion can be further reduced. As a result, it is possible to satisfy the requirements for downsizing and low profile and to wind the primary winding or the secondary winding with a desired number of turns.

  Here, the substantially cylindrical portion has a mounting substrate facing portion that faces the mounting substrate, and the terminal electrode is disposed at an axial end of the substantially cylindrical portion and is a part of the highly insulated winding. Thus, it is preferable that the portion led out from the second section to the terminal electrode is opposed to the mounting substrate facing portion.

  When the transformer is mounted on the mounting board, the primary winding, the secondary winding, and the high-insulation winding wound around the bobbin are mounted so as to be separated from the mounting board by a predetermined distance. Since the part of the high-insulation winding that is led out from the second section to the terminal electrode is opposed to the mounting substrate facing portion, the primary winding thus separated by a predetermined distance is used. The space between the wiring board and the mounting substrate can be effectively used as a space for drawing out the highly insulated winding to the terminal electrode.

  The cross-sectional shape of the substantially cylindrical portion cut by a plane orthogonal to the axial direction of the substantially cylindrical portion is a substantially rectangular shape having a bottom wall, a top wall, and a pair of side walls parallel to each other. Preferably, the high-insulation winding is led out to the terminal electrode from a position that is a part of the second section and faces the end of the bottom wall.

  When the primary winding, the secondary winding, and the high insulation winding have a substantially rectangular shape in which the cross-sectional shape of the substantially cylindrical portion has a bottom wall, a top wall, and a pair of side walls parallel to each other. They are wound around the outer peripheral surface of the substantially cylindrical portion so as to be in contact with the end portions of the bottom wall, the top wall, and the side wall, that is, in contact with the corner portions of the substantially rectangular shape. The cross-sectional shape of the substantially cylindrical portion cut by a plane orthogonal to the axial direction of the substantially cylindrical portion is a substantially rectangular shape having a bottom wall, a top wall, and a pair of side walls parallel to each other. Since it is a part of the two sections and is pulled out to the terminal electrode from a position facing the end of the bottom wall, the high-insulation winding is provided from a position as close as possible to the outer peripheral surface of the substantially cylindrical portion that defines the second section. When the transformer is mounted on the mounting board, the highly insulated winding can be drawn at a position as far as possible from the mounting board.

  The high-insulation winding is preferably made of a three-layer insulated wire. Since the high-insulation winding is made of a three-layer insulation wire, the distance between the primary winding and the secondary winding in the axial direction of the substantially cylindrical portion can be further reduced.

  Moreover, it is preferable that this convex part is comprised integrally with this case main-body part. Since the convex portion is configured integrally with the case main body portion, the configuration of the case can be simplified.

  As described above, the present invention can provide a transformer that is sufficiently miniaturized.

The top view which shows the transformer by embodiment of this invention. The bottom view which shows the trans | transformer by embodiment of this invention. Sectional drawing which shows the trans | transformer by embodiment of this invention. The bottom view which shows the primary winding, secondary winding, auxiliary | assistant winding, and bobbin of the transformer by embodiment of this invention. 1 is a circuit diagram showing a transformer according to an embodiment of the present invention.

  A transformer according to an embodiment of the present invention will be described with reference to FIGS. The transformer 1 includes a core 10 (FIG. 2 etc.), a bobbin 20 (FIG. 3 etc.), a conducting wire 50 (FIG. 3 etc.), and a case 40 (FIG. 1 etc.). In the following description, the upper direction in FIG. 1 is defined as the right direction and the lower direction is defined as the left direction. In addition, the left direction in FIG. 1 is defined as the front direction, and the right direction is defined as the rear direction. 1 is defined as the downward direction, and the direction from the back surface to the front surface of FIG. 1 is defined as the upward direction.

  A pair of cores 10 having the same shape is provided. The core 10 has a substantially E-shape as a whole, and has a bottom wall portion 10A (FIG. 3) and a pair of side wall portions 10B extending so as to be separated from one end and the other end of the bottom wall portion 10A. 2) and a central wall portion 10C (FIG. 3) extending away from the central portion of the bottom wall portion 10A. The side wall portion 10B corresponds to a surrounding portion, and the central wall portion 10C corresponds to an insertion portion. As shown in FIG. 2, the extended ends of the pair of side wall portions 10 </ b> B of one core 10 are in contact with the extended ends of the side wall portions 10 </ b> B of the other core 10. The extended end of the central wall portion 10C of one core 10 does not contact the extended end of the central wall portion 10C of the other core 10, and they are separated by a small distance. Since this distance is very small, in FIG. 3, it appears as if it is in contact for convenience of drawing.

  The bobbin 20 (FIG. 4) is formed of an insulating resin and has a substantially cylindrical shape. The bobbin 20 has a substantially cylindrical portion 21 provided with terminal blocks 31 and 32 at both axial ends. The substantially cylindrical portion 21 has a bottom wall 21D and an upper wall 21E in which a cross-sectional shape cut by a plane orthogonal to the axial direction of the substantially cylindrical portion 21 forms a pair of parallel linear shapes, and a pair of parallel linear shapes. A substantially rectangular shape having a substantially rectangular shape having a side wall (not shown). A central wall portion 10 </ b> C of the core 10 is inserted into a space 21 a (FIG. 3) defined by the inner peripheral surface of the substantially cylindrical portion 21. The length of the substantially cylindrical portion 21 in the axial direction is about 31 mm. A bottom wall 21D of the substantially cylindrical portion 21 is parallel to and opposed to the surface of a mounting substrate (not shown) on which the transformer 1 is mounted, and corresponds to a mounting substrate facing portion.

  Partition plates 22 and 23 are provided on the peripheral surface of the substantially cylindrical portion 21. As shown in FIGS. 2 to 4, the partition plates 22 and 23 are erected in a plate shape over the entire circumference along the circumferential direction of the outer peripheral surface of the substantially cylindrical portion 21. The peripheral surface of the substantially cylindrical portion 21 is partitioned into three sections, a first section 21A, a second section 21B, and a third section 21C, in the axial direction of the substantially cylindrical portion 21, by the partition plates 22 and 23, The partition plates 22 and 23 and the second section 21B form a groove shape.

  The length from the upper end of the partition plates 22 and 23 to the lower end of the partition plates 22 and 23 in the vertical direction is about 15 mm, and the distance between the partition plates 22 and 23 in the axial direction of the substantially cylindrical portion 21 is larger than 1 mm. It is necessary to be a value, for example, about 1.2 mm.

  As shown in FIG. 4, lead-out grooves 22 a and 22 b are formed in a part of the partition plate 22 and provided on the bottom wall 21 </ b> D (FIG. 3) of the substantially cylindrical portion 21. The lead-out grooves 22a and 22b are part of the partition plate 22 and are formed at the front and rear ends, respectively, and the axial direction of the substantially cylindrical portion 21 so as to connect the first section 21A and the second section 21B. Is formed.

  The terminal blocks 31 and 32 are provided at one end and the other end of the substantially cylindrical portion 21 in the axial direction. The terminal blocks 31 and 32 are made of the same insulating resin as the substantially cylindrical portion 21 and are integrated with the bottom wall 21 </ b> D of the substantially cylindrical portion 21. The terminal blocks 31 and 32 each extend in the front-rear direction, that is, in a direction orthogonal to the axial direction of the substantially cylindrical portion 21. One terminal block 31 has terminal electrodes 61, 62, 63, 64, 65, 66, 67, 68 made of nine metal L-shaped pins (FIG. 3) at predetermined intervals in the extending direction. 69 extend from the terminal block 31 in a direction from right to left and in a direction from top to bottom, respectively. The other terminal block 32 has terminal electrodes 71, 72, 73, 74, 75, 76, 77, 78 made of eight metal L-shaped pins at predetermined intervals in the extending direction. They extend from the terminal block 32 in a direction from left to right and in a direction from top to bottom, respectively. Convex portions 31A, 31B, 31C, 31D, 31E, 31F, 31G, 31H, and 31I extending in the axial direction of the substantially cylindrical portion 21 are provided on the bottom surface of the terminal block 31. On the bottom surface of the terminal block 32, convex portions 32A, 32B, 32C, 32D, 32E, 32F, 32G, and 32H extending in the axial direction of the substantially cylindrical portion 21 are provided.

  As shown in FIG. 3, the conducting wire 50 has a primary winding 51, an auxiliary winding 54, a first secondary winding 52, and a second secondary winding 53. The primary winding 51, the first secondary winding 52, and the second secondary winding 53 are each made of a copper wire with an insulating coating such as urethane. The auxiliary winding 54 has a three-layer insulating coating that is a highly insulating coating having a higher insulating property than the insulating coating of the primary winding 51, the first secondary winding 52, and the second secondary winding 53. It is comprised by the three-layer insulation wire (Applicable safety standard: IEC60065 etc.) which consists of a copper wire to which (1) was given.

  The primary winding 51 is wound around the first section 21 </ b> A so as not to protrude in the vertical direction and the front-rear direction than the partition plates 22 and 23, and is drawn out toward the terminal block 31. It is passed between the convex portion 31C and between the convex portion 31D and the convex portion 31E. The one end and the other end are wound around the terminal electrodes 62 and 64, respectively, and the wound portions are electrically connected to the terminal electrodes 62 and 64 by soldering or the like. 2 and 4, for convenience of explanation, one end and the other end of the primary winding 51 are illustrated as being wound around the terminal electrodes 62 and 64, respectively. The same applies to the first secondary winding 52, the second secondary winding 53, and the auxiliary winding 54.

  The first secondary winding 52 is wound around the third section 21 </ b> C so as not to protrude in the vertical direction and the front-rear direction from the partition plates 22, 23, drawn toward the terminal block 32, and protruded at the terminal block 32. It is passed between the convex part 32E and the convex part 32F between the convex part 32B and the convex part 32C. The one end and the other end are wound around the terminal electrodes 72 and 76, respectively, and the wound portions are electrically connected to the terminal electrodes 72 and 76 by soldering or the like.

  Similarly, the second secondary winding 53 has a first section wound on the third section 21 </ b> C around which the first secondary winding 52 is wound so as not to protrude in the vertical and horizontal directions from the partition plates 22 and 23. It is wound around the secondary winding 52, drawn out toward the terminal block 32, and passed through the terminal block 32 between the convex portions 32C and 32D and between the convex portions 32F and 32G. ing. The one end and the other end are wound around the terminal electrodes 73 and 77, respectively, and the wound portions are electrically connected to the terminal electrodes 73 and 77 by soldering or the like.

  The auxiliary winding 54 is wound around the second section 21 </ b> B so as not to protrude in the vertical direction and the front / rear direction than the partition plates 22 and 23, and is passed through the drawing groove 22 a of the partition plate 22. A position facing the above-described bottom wall 21D defining the cross-sectional shape and passing through a position facing the end of the bottom wall 21D in a direction orthogonal to the axial direction of the substantially cylindrical portion 21 is directed toward the terminal block 31. In the terminal block 31, it is passed between the convex part 31G and the convex part 31H and between the convex part 31H and the convex part 31I. The one end and the other end are wound around the terminal electrodes 68 and 69, respectively, and the wound portions are electrically connected to the terminal electrodes 68 and 69 by soldering or the like.

  On the mounting board (not shown), the auxiliary winding 54 is electrically connected to the IC (not shown) in order to supply a power supply voltage to the IC (not shown) for driving and controlling the transformer 1. Thus, since the power supply voltage can be supplied to the IC (not shown) by the auxiliary winding 54, it is not necessary to provide a transformer separate from the transformer 1 in order to supply the power supply voltage to the IC (not shown), thereby reducing the cost. be able to. The first section 21A and the third section 21C are not shown in FIG. 4 for convenience of explanation, but as shown in FIG. 2, the primary winding 51 and the second secondary winding 53 are shown. Insulating tapes 81 and 82 are wound on the drawn portions of the auxiliary winding 54 so as to cover them.

  The case 40 is made of an insulating resin and covers the entire upper side, the entire left side, the entire right side, the entire front side, and the entire rear side of the bobbin 20 as shown in FIGS. A portion of the case 40 that is opposed to the end opening of the space 21a defined by the inner peripheral surface of the substantially cylindrical portion 21 has a through-hole 40a having substantially the same shape as the end opening (FIG. 3). ) Are formed. The central wall portion 10C of the core 10 described above passes through the through hole 40a, and the central wall portion 10C penetrating the through hole 40a is inserted into a space 21a defined by the inner peripheral surface of the substantially cylindrical portion 21. . With such a configuration, the core 10 is not directly opposed to any of the primary winding 51, the auxiliary winding 54, the first first secondary winding 52, and the second secondary winding 53. The case 40 or the bobbin 20 is interposed between the secondary winding 51, the auxiliary winding 54, the first first secondary winding 52, the second secondary winding 53, and the core 10. ing. The primary winding 51, the auxiliary winding 54, the first first secondary winding 52, and the portion of the case 40 interposed between the second secondary winding 53 and the core 10 are the case body. It corresponds to the part.

  Further, the uppermost portion of the case 40 has a substantially rectangular plate-like portion 40A (FIG. 1), and the upper surface of the plate-like portion 40A is a recess recessed downward except for the edge of the plate-like portion 40A. 40b is formed. A substantially rectangular metal plate 41 is provided in the recess 40b. Since the metal plate 41 is provided, leakage flux generated by the conductive wire 50 mounted on a mounting board (not shown) and supplied with power can be shielded (shielded) in the metal plate 41. For this reason, even when another metal plate or the like is disposed at a position facing the transformer 1 mounted on a mounting board (not shown), the other metal plate can be prevented from being heated. .

  Further, a plate-like rib 40 </ b> B (FIG. 2) extending in a direction orthogonal to the axial direction of the substantially cylindrical portion 21 is provided on the lower surface of the case 40 and facing the second section 21 </ b> B. The plate-like rib 40B corresponds to a convex portion. The plate-like rib 40B is provided on the lower surface of the case 40, on the portion facing the upper wall 21E of the substantially cylindrical portion 21 and on the portion facing the pair of side walls (not shown), as shown in FIG. It is inserted between the partition plates 22 and 23. Since the plate-like rib 40B is provided, the creeping distance between the primary winding 51, the first secondary winding 52, and the second secondary winding 53 can be secured longer than a predetermined value. . For this reason, the distance between the primary winding 51 in the axial direction of the substantially cylindrical portion 21, the first secondary winding 52, and the second secondary winding 53 can be further reduced. Further, since the plate-like rib 40B is formed integrally with the case main body portion of the case 40, the configuration of the case 40 can be simplified.

  Also, a primary winding 51 made of a conductive wire covered with an insulating film, wound around the first section 21A and electrically connected at one end and the other end to the terminal electrodes 62 and 64, and covered with an insulating film. The first secondary winding 52, the second secondary winding, which is made of a conductive wire and wound around the third section 21C and having one end and the other end electrically connected to the terminal electrodes 72, 73, 76, 77 The wire 53 is composed of a three-layer insulated wire covered with an insulating film having a higher insulating property than the insulating film of the primary winding 51, the first secondary winding 52, and the second secondary winding 53. Since the auxiliary winding 54 wound around the two sections 21B is provided, the conventional primary winding 51 is separated from the first secondary winding 52 and the second secondary winding 53 by a predetermined distance. The part that was the dead space for the auxiliary winding 54 It can be effectively utilized as over the nest. For this reason, coupled with the configuration in which the plate-like ribs 40B are inserted between the partition plates 22 and 23, the requirements for miniaturization and low profile of the transformer 1 are satisfied, and the primary winding 51 has a desired number of turns. The first secondary winding 52 and the second secondary winding 53 can be wound. Further, since the auxiliary winding 54 is made of a three-layer insulated wire, it is between the primary winding 51 and the first secondary winding 52 and the second secondary winding 53 in the axial direction of the substantially cylindrical portion 21. Can be further reduced.

  When the transformer 1 is mounted on a mounting board (not shown), the primary winding 51 wound around the bobbin 20, the first secondary winding 52, the second secondary winding 53, and the auxiliary winding The line 54 is mounted so as to be separated from the mounting substrate (not shown) by a predetermined distance. As described above, a part of the auxiliary winding 54 that is drawn from the second section 21B to the terminal electrodes 68 and 69 is opposed to the mounting substrate facing portion, and thus is separated by a predetermined distance. The space between the primary winding 51 and the mounting substrate that are separated from each other can be effectively used as a space for drawing the auxiliary winding 54 to the terminal electrodes 68 and 69.

  The primary winding 51, the first secondary winding 52, the second secondary winding 53, and the auxiliary winding 54 have a substantially cylindrical cross-sectional shape at the bottom as in the present embodiment. If the wall 21D and the upper wall 21E have a substantially rectangular shape having a pair of side walls parallel to each other, they are in contact with the bottom wall 21D, the upper wall 21E, and the end portions of the side walls, that is, substantially rectangular. It will be in the state wound by the outer peripheral surface of the substantially cylindrical part 21 so that a corner | angular part might be contacted. Since the auxiliary winding 54 is a part of the second section 21B and is led out to the terminal electrodes 68 and 69 from a position facing the end of the bottom wall 21D, a substantially cylindrical portion that defines the second section 21B. The auxiliary winding 54 can be pulled out from a position as close as possible to the outer peripheral surface of 21, and the auxiliary winding 54 can be pulled out at a position as far as possible from the mounting board when the transformer 1 is mounted on the mounting board.

  The transformer of the present invention is not limited to the above-described embodiment, and various modifications and improvements can be made within the scope described in the claims. For example, in the present embodiment, the plate-like rib 40B is configured integrally with the case main body portion of the case 40, but is not limited to this configuration.

  In the present embodiment, the auxiliary winding 54 is electrically connected to the IC (not shown) in order to supply the power supply voltage to the IC (not shown) for driving and controlling the transformer 1. The configuration is not limited to this.

  The substantially cylindrical portion 21 has a cross-sectional shape cut by a plane orthogonal to the axial direction of the substantially cylindrical portion 21 and a side wall (not shown) forming a pair of parallel straight lines and a pair of parallel straight lines. Although it has made the substantially rectangular shape of the substantially rectangular shape which has the wall 21E and the bottom wall 21D, it is not limited to this shape. For example, the cross-sectional shape may be circular.

  The terminal blocks 31 and 32 are provided at both ends in the axial direction of the substantially cylindrical portion 21, but are not limited to being provided at this position. Accordingly, the terminal electrodes are also provided at both ends in the axial direction of the substantially cylindrical portion. It is not limited to that.

  Moreover, although the outer peripheral surface of the substantially cylindrical part 21 was partitioned into three sections of the first section 21A to the third section 21C, it is not limited to three and may be partitioned further. Accordingly, there may be a plurality of sections around which the primary winding 51 is wound, and a plurality of sections around which the secondary winding 52 is wound. Even in this case, a section in which the auxiliary winding 54 is wound is provided between the section in which the primary winding 51 is wound and the section in which the secondary windings 52 and 53 are wound. The configuration is as follows.

  In the transformer of the present invention, in particular, the peripheral surface of the substantially cylindrical portion of the bobbin is partitioned into a plurality of sections in the axial direction of the substantially cylindrical portion, and the primary winding and the secondary winding are wound in separate sections. It is particularly useful in the field of transformers.

DESCRIPTION OF SYMBOLS 1 Transformer 10 Core 20 Bobbin 21 Substantially cylindrical part 21A 1st section 21B 2nd section 21C 3rd section 22, 23 Partition plate 22a Pull-out groove 40 Case 40B Plate-shaped rib 51 Primary winding 52 1st secondary winding 53 Second secondary winding 54 Auxiliary winding 61, 62, 63, 64, 65, 66, 67, 68, 69, 71, 72, 73, 74, 75, 76, 77, 78 Terminal electrode

Claims (5)

A bobbin having a substantially cylindrical portion made of an insulating material, and having a first section, a second section, and a third section, the outer peripheral surface of the substantially cylindrical portion being arranged adjacent to each other in the axial direction of the substantially cylindrical portion;
A terminal electrode provided on the bobbin;
A core having an insertion portion inserted into a space defined by the inner peripheral surface of the substantially cylindrical portion and a surrounding portion surrounding the cylindrical portion;
A primary winding made of a conductive wire coated with an insulating coating, wound around the first section, and having one end and the other end electrically connected to the terminal electrode;
A secondary winding made of a conductive wire covered with an insulating coating, wound around the third section and having one end and the other end electrically connected to the terminal electrode;
A high-insulation winding made of a conductive wire coated with an insulating coating having a higher insulating property than the insulating coating of the primary winding and the secondary winding and wound around the second section;
At the boundary between the first section and the second section, and at the boundary between the second section and the three sections, partition plates extending in the circumferential direction of the substantially cylindrical portion are respectively erected, The first section and the second section are partitioned by the partition plate, and the second section and the third section are partitioned by the partition plate, whereby the second section has a groove shape,
A case having a convex portion that engages with the groove-shaped second section, and a case main body disposed between the primary winding, the secondary winding, and a highly insulated winding and the core. A transformer characterized by comprising. The substantially cylindrical portion has a mounting substrate facing portion facing the mounting substrate,
The terminal electrode is disposed at an axial end of the substantially cylindrical portion;
2. The transformer according to claim 1, wherein a part of the high-insulation winding that is led out from the second section to the terminal electrode is opposed to the mounting substrate facing part. The cross-sectional shape of the substantially cylindrical portion cut by a plane perpendicular to the axial direction of the substantially cylindrical portion is a substantially rectangular shape having a bottom wall, a top wall, and a pair of side walls parallel to each other, and the bottom wall is Make the mounting substrate facing part,
The transformer according to claim 2, wherein the high-insulation winding is led out to the terminal electrode from a position that is a part of the second section and faces an end of the bottom wall.   The transformer according to any one of claims 1 to 3, wherein the high-insulation winding comprises a three-layer insulated wire.   The transformer according to any one of claims 1 to 4, wherein the convex portion is formed integrally with the case main body portion.

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