Transformer and method for manufacturing the same

Abstract

This transformer (100) comprises: a bobbin (30) that extends in a winding axis direction; a first coil (11); a second coil (12); an interlayer tape (50); and one or more creepage surface tapes (60). The first coil (11) is wound inside among multiple coils (10) wound in layers about the bobbin (30). The second coil (12) is wound outside of the first coil (11). The interlayer tape (50) is wound between the first coil (11) and the second coil (12). The creepage surface tapes (60), when viewed in the winding axis direction, are wound outside of the first coil (11) or the second coil (12). At least some of the creepage surface tapes (60) and the interlayer tape (50) serve as an insulating tape (40) that is a single member.

Description

[Technical Field]

[0001] The present invention relates to a transformer, a bobbin set for forming such a transformer, and a method for manufacturing such a transformer. [Background technology]

[0002] Some transformers have multiple windings wound in layers around a bobbin. When multiple windings are wound in layers, they must be insulated from each other to prevent short circuits between the windings. Specifically, a creepage distance of at least the specified value must be maintained between the windings. Regarding this type of technology, Patent Document 1 below discloses a transformer in which three windings (21, 22, 23) are wound in layers around a bobbin (12) in order, as shown in FIG. 5 of the document, and an interlayer tape (13) and an insulating barrier tape (14) are arranged around the windings (21, 22, 23). Specifically, three windings (21, 22, 23) are wound around a winding shaft portion of a bobbin (12), and both ends (21a, 22a, 23a) of the windings are pulled out to one axial side of the bobbin (12) (the right side in Figure 5 of Patent Document 1). An interlayer tape (13) is wound between the windings (21, 22, 23) wound around the bobbin (12). In addition, an insulating barrier tape (14) is wound around both outer sides of the windings (21, 22, 23) in the axial direction of the bobbin (12). That is, each winding (21, 22, 23) is wound in an area inside a pair of insulating barrier tapes (14). With this configuration, the width of each insulation barrier tape 14 (the axial length of the bobbin 12) ensures a certain distance along the surface of the insulator between the first-layer winding 21 and the second-layer winding 22. The same applies to the second-layer winding 22 and the third-layer winding 23. For example, as shown in FIG. 5 of Patent Document 1, one of the locations where the first-layer winding 21 and the second-layer winding 22 are close to each other along the surface of the insulator is between the left end of the first-layer winding 21 and the left end of the second-layer winding 22. The minimum length along the surface of the insulator between the left end of the first-layer winding 21 and the left end of the second-layer winding 22 (creepage distance) is equal to or greater than the sum of the widths of the insulation barrier tape 14 wound on the left side of the first-layer winding 21 and the second-layer winding 22. Another point where the first-layer winding (21) and the second-layer winding (22) are close to each other is between the right end of the first-layer winding (21) and the end (22a) of the second-layer winding (22) on the inner surface of the flange of the bobbin (12) (the position where it is drawn out to the flange). The creepage distance between these two points is equal to or greater than the width of the insulating barrier tape (14) wound around the right side of the first-layer winding (21). Similarly, the creepage distance between the end (21a) of the first-layer winding (21) and the right end of the second-layer winding (22) is equal to or greater than the width of the insulating barrier tape (14) wound around the right side of the second-layer winding (22). The smallest of these creepage distances is the creepage distance between the windings (21) and (22). It is assumed that the end 21a of the first layer winding 21 and the end 22a of the second layer winding 22 are sufficiently spaced apart in the depth direction of the drawing. In this way, by arranging the insulating barrier tape (14) outside the windings (21, 22, 23) in the axial direction of the bobbin (12), the windings (21, 22, 23) are spaced apart by the width of the insulating barrier tape (also called creepage tape), thereby ensuring the creepage distance between the windings. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 6-132144 Summary of the Invention [Problem to be solved by the invention]

[0004] As described above, the creepage distance can be secured by placing the insulating barrier tape on the outer side of the winding in the axial direction, but adding the step of winding the insulating barrier tape to the transformer manufacturing process increases the number of manufacturing steps for the transformer, which poses a problem of reduced transformer manufacturing efficiency.

[0005] The present invention has been made in view of the above-mentioned problems, and provides a transformer that requires few manufacturing steps while maintaining the creepage distance between windings at or above a specified value, a bobbin set for manufacturing such a transformer, and a method for manufacturing the transformer. [Means for solving the problem]

[0006] The transformer of the present invention includes a bobbin extending in a winding axis direction, a first coil wound inside of a plurality of coils wound in layers around the bobbin, a second coil wound outside the first coil, an interlayer tape wound between the first coil and the second coil, and one or more creepage tapes wound outside the first coil or the second coil in the winding axis direction, wherein at least a part of the creepage tape and the interlayer tape form an insulating tape of a single component. a second insulating tape including a wide portion wound around the outside of a portion of the second coil and having a width equal to or greater than the length of the winding axis direction of the winding shaft portion of the bobbin, a notch being provided at one end in the longitudinal direction of the wide portion, and the second coil being disposed across the inside and outside of the second insulating tape through the notch; .

[0008] The method for manufacturing a transformer of the present invention includes: a bobbin extending in a winding axis direction; a first coil wound inside a plurality of coils wound in layers around the bobbin; a second coil wound outside the first coil; and an insulating tape wound around the bobbin. a second insulating tape wound around the outside of a portion of the second coil and including a wide portion having a width equal to or greater than the length of the winding axis of the winding shaft portion of the bobbin;the insulating tape has an interlayer tape portion wound between the first coil and the second coil, and a creeping tape portion wound around the outside of the first coil or the second coil in the winding axis direction, the interlayer tape portion and the creeping tape portion being formed as a single insulating tape; a notch is provided at one end of the wide portion of the second insulating tape in the longitudinal direction, and the second coil is disposed across the inside and outside of the second insulating tape through the notch; a first coil winding step of winding the first coil around the bobbin, an insulating tape winding step of winding a part of the interlayer tape section and the surface tape section continuously around the bobbin, and a second coil winding step of winding the second coil around the outside of the interlayer tape section. After the second coil winding process, the second insulating tape is placed on the outside of the second coil, and one end of the second coil winding is pulled out from the inside to the outside of the second insulating tape through the notch. [Effects of the Invention]

[0009] According to the present invention, the surface tape and the interlayer tape are formed as a single insulating tape, so that the surface tape and the interlayer tape can be wound continuously, thereby reducing the number of manufacturing steps. [Brief explanation of the drawings]

[0010] The above-mentioned objects, as well as other objects, features and advantages, will become more apparent from the preferred embodiments described below and the accompanying drawings.

[0011] [Figure 1] 5(d) is a longitudinal cross-sectional view of the transformer according to the first embodiment taken along the dashed line in FIG. 5(d) and seen in the direction of the arrow II. [Figure 2] 5(d) is a longitudinal cross-sectional view of the transformer according to the first embodiment taken along the dashed dotted line shown in FIG. 5(d) and seen in the direction of the arrows II-II. [Figure 3] 1A is a schematic diagram illustrating a step of winding a first creeping tape in a manufacturing process of a transformer according to a first embodiment, and FIG. 1B is a schematic diagram illustrating the transformer on which a first coil is wound. [Figure 4]1A is a schematic diagram of a transformer in which an insulating tape is arranged during the manufacturing process of the transformer according to the first embodiment, (b) and (c) are schematic diagrams of the transformer in the middle of winding the insulating tape, and (d) is a schematic diagram of the transformer in the middle of winding the second coil. [Figure 5] 1A is a schematic diagram of a transformer on which a second coil is wound in a manufacturing process of a transformer according to a first embodiment; FIG. 1B is a schematic diagram of a transformer on which an outer peripheral tape is arranged; FIG. 1C is a schematic diagram of a transformer after the second coil winding process has been completed; and FIG. 1D is a schematic diagram of the appearance of a transformer according to a first embodiment. [Figure 6] 6A is a schematic diagram of the appearance of a transformer according to a second embodiment, and FIG. 6B is a longitudinal sectional view of the transformer according to the second embodiment taken along the dashed line in FIG. 6A, as viewed in the direction of the arrows VI-VI. [Figure 7] 10A is a schematic diagram of a transformer in a first coil winding stage in a manufacturing process of a transformer according to a second embodiment, and FIG. 10B is a schematic diagram of the transformer with a jig attached thereto. [Figure 8] 10A is a schematic diagram of a transformer on which an insulating tape is arranged during the manufacturing process of a transformer according to a second embodiment, and FIG. 10B is a schematic diagram of the transformer after the first coil winding process. [Figure 9] 10A is a schematic diagram of the appearance of a transformer according to a third embodiment, and FIG. 10B is a schematic diagram of the transformer with an insulating tape disposed thereon. [Figure 10] 9A is a longitudinal cross-sectional view of a transformer according to a third embodiment taken along the dashed line in FIG. 9A, as viewed in the direction of the arrow Xa-Xa; and FIG. 9B is a longitudinal cross-sectional view of a transformer according to a third embodiment taken along the dashed line in FIG. 9A, as viewed in the direction of the arrow Xb-Xb. [Figure 11] 11(a) is a schematic diagram of the appearance of a transformer according to a fourth embodiment, and FIG. 11(b) is a cross-sectional view taken along line XI-XI in FIG. 11(a) as viewed in the direction of the arrows. [Figure 12]10A is a schematic diagram of a transformer in which a partition tape is arranged during the manufacturing process of a transformer according to a fifth embodiment, FIG. 10B is a schematic diagram of the transformer in the middle of winding the partition tape, and FIG. 10C is a schematic diagram of the transformer after the second coil winding process has been completed. [Figure 13] 10(a) and 10(b) are schematic diagrams of a transformer in the manufacturing process of a transformer according to a fifth embodiment, in which a second tape is being wound, and FIG. 10(c) is a schematic diagram of a transformer in which a third coil is being wound. [Figure 14] 10A is a schematic diagram of a transformer in which a partition tape is arranged during a manufacturing process of a transformer according to a fifth embodiment, FIG. 10B is a schematic diagram of a transformer after winding of the partition tape is completed, FIG. 10C is a schematic diagram of a transformer after a third coil winding process is completed, and FIG. 10D is a schematic diagram of the external appearance of a transformer according to a fifth embodiment. [Figure 15] 15 is a longitudinal cross-sectional view of the transformer according to the fifth embodiment taken along the dashed dotted line shown in FIG. 14(d) and seen in the direction of the arrow XV-XV. [Figure 16] 16 is a longitudinal cross-sectional view of the transformer according to the fifth embodiment taken along the dashed dotted line shown in FIG. 14(d), as viewed in the direction of the arrows XVI-XVI. DETAILED DESCRIPTION OF THE INVENTION

[0012] The various components of the transformer and bobbin set of the present invention do not need to be independent entities, and it is acceptable for multiple components to be formed as a single member, for one component to be formed from multiple members, for one component to be part of another component, or for part of one component to overlap with part of another component, etc. Although the transformer manufacturing method of the present invention may be described using multiple steps listed in a sequential order, the order of the steps does not limit the order or timing of performing the multiple steps. Therefore, when implementing the transformer manufacturing method of the present invention, the order of the multiple steps may be changed as long as it does not cause any problems in terms of the content, and some or all of the timing of performing the multiple steps may overlap with each other.

[0013] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. In the drawings, corresponding components are designated by common reference numerals, and duplicated descriptions will be omitted as appropriate. In this embodiment, the winding axis direction of the bobbin 30 may be referred to as the left-right direction. Specifically, the side of the winding axis direction from which both ends of the first coil 11 are pulled out is referred to as the left side, and the side opposite the left side is referred to as the right side. For example, in FIG. 1, the left side of the page is the left side of the transformer 100, and the right side of the page is the right side. Also, in FIG. 3(a), the upper side of the page is the left side, and the lower side of the page is the right side. However, this definition is given for convenience in order to easily explain the relative relationships between the components, and does not limit the directions during manufacture or use of a product embodying the present invention. Furthermore, the term "flat surface" as used in the present invention means a shape that is physically formed with a flat surface as a target, and it is not necessarily required that the surface be a geometrically perfect flat surface.

[0014] First Embodiment (transformer)

[0015] First, an overview of the transformer 100 of this embodiment will be described. The transformer 100 has a bobbin 30 extending in the winding axis direction, a first coil 11, a second coil 12, an interlayer tape 50, and one or more creepage tapes 60. The first coil 11 is wound on the inside of the multiple coils 10 wound in layers around the bobbin 30. The second coil 12 is wound on the outside of the first coil 11. The interlayer tape 50 is wound between the first coil 11 and the second coil 12. The creepage tape 60 is wound on the outside of the first coil 11 or the second coil 12 when viewed in the winding axis direction. At least a portion of the creepage tape 60 and the interlayer tape 50 form a single insulating tape (integrated insulating tape 40).

[0016] Next, the transformer 100 of this embodiment will be described in detail with reference to Figures 1 and 2. Note that hatching showing cross sections of the coil 10 and bobbin 30 is omitted in Figures 1 and 2. The same applies to Figures 6(b), 10(a), 10(b), 11(b), 15, and 16. The same type of hatching is used to indicate cross sections of the same members. 1 and 2, for convenience, gaps are shown between the first surface-creeping tape 61b and the interlayer tape 50, and between the second surface-creeping tape 62a and the outer peripheral tape 70, but in reality the tapes are in close contact with each other. The same applies to gaps between tapes in other embodiments described below (such as the interlayer tape 50, the surface-creeping tape 60, the outer peripheral tape 70, the second interlayer tape 52, and the partition tape 80).

[0017] The bobbin 30 is a member around which the coil 10 is wound. The bobbin 30 has a winding shaft portion 31, which is a portion around which the coil 10 and tapes such as the surface tape 60 and the interlayer tape 50 are wound. The length of the winding shaft portion 31 in the direction of the winding axis may be longer or shorter than the diameter of a flange portion 32, which will be described later. In this embodiment, the bobbin 30 has a pair of flanges 32 spaced apart in the winding axis direction. The flanges 32 protrude radially from the circumferential surface of the winding shaft 31. Hereinafter, the radial direction refers to a direction that radiates from the axial center of the bobbin 30 toward the periphery. Hereinafter, the above-mentioned direction will be referred to as the radial direction even when the cross section of the winding shaft 31 or flanges 32 is polygonal rather than circular. The flanges 32 may be provided at both ends of the bobbin or midway along the length of the winding axis direction of the bobbin 30. The winding shaft portion 31 is an area sandwiched between a pair of flanges 32 (flange portion 32b and flange portion 32c). If the bobbin 30 does not have flange portion 32, the area of ​​the bobbin 30 around which the first coil 11, the second coil 12, and the surface tape 60 are wound can be the winding shaft portion 31.

[0018] The bobbin 30 has terminals 33. In this embodiment, as shown in FIG. 3(a), the bobbin 30 has a plurality of terminals 33 on the left side (upper side of the paper) and right side (lower side of the paper), specifically, four on each side, for a total of eight terminals (terminals 331 to 338). As an alternative to this embodiment, the bobbin 30 may have terminals 33 only on either the left or right side, as in a fourth embodiment described later. Furthermore, the number of terminals is not limited to eight, and may be four or more. As an example, the transformer 100 is surface-mounted on a mounting board (not shown) for use. For example, as shown in FIGS. 1 and 2, the terminal 33 has a parallel surface 33a parallel to the winding axis direction. The transformer 100 is placed on the mounting board so that the parallel surface 33a is grounded to the mounting board. That is, the transformer 100 in this embodiment is a horizontal transformer in which the winding axis portion 31 is placed parallel to the mounting board. The terminal 33 and the mounting board are joined by soldering or the like. In this embodiment, the terminal 33 has a flat surface (parallel surface 33a) for surface mounting, but this is not limiting. For example, the terminal 33 may be a pin-shaped terminal that is inserted into the mounting board for use.

[0019] The coil 10 is a linear member made of a conductive metal material such as copper. In this embodiment, the transformer 100 has a first coil 11 and a second coil 12 as the coils 10. In a fifth embodiment described later, the transformer 100 further has a third coil 13 as the coils 10. Two or more coils 10 are wound in layers around the bobbin 30. Here, "the coils 10 are wound in layers" means that the coil 10 (e.g., the first coil 11) wound on the lower layer side (radially inward) and the coil 10 (e.g., the second coil 12) wound on the upper layer side (radially outward) thereof at least partially overlap each other when viewed in the radial direction of the bobbin 30. Preferably, substantially the entire area of ​​the coil 10 wound on the lower layer side (the first coil 11) and substantially the entire area of ​​the coil 10 wound on the upper layer side (the second coil 12) overlap each other when viewed in the radial direction of the bobbin 30. Furthermore, the coil 10 wound on the lower layer side here is sufficient to be wound on the lower layer side of at least one other coil 10, and is not limited to being wound on the lowest layer. Similarly, the coil 10 wound on the upper layer side is sufficient to be wound on the upper layer side of at least one other coil 10, and is not limited to being wound on the highest layer. In the present embodiment, the first coil 11 is a coil 10 wound in the first layer of the winding shaft portion 31, and the second coil 12 is a coil 10 wound in the second layer of the winding shaft portion 31, but this is not limiting. For example, the first coil 11 may be a coil 10 wound in a plurality of layers of the winding shaft portion 31, and the second coil 12 may be a coil 10 wound in the layer immediately above the first coil 11.

[0020] Coil 10 is wound around winding shaft portion 31, and both ends of coil 10 are pulled out radially from winding shaft portion 31 along inner surface 32a of flange portion 32. The portion of coil 10 wound around winding shaft portion 31 is called a winding portion (first winding portion 11b, second winding portion 12b in FIG. 1). The portion of coil 10 pulled out from winding shaft portion 31 to terminal 33 is called a pull-out portion (first pull-out portion 11a, second pull-out portion 12a in FIG. 1). The pull-out portion is a partial length region of coil 10 extending from one end of the winding portion to the other end wound around terminal 33. Furthermore, a part of the lead-out portion that is arranged along the winding axis direction is called a start portion or a feedback portion (first start portion 11e, second start portion 12e, first feedback portion 11f, and second feedback portion 12f in FIGS. 1 and 2). Coil 10 has a start portion at one end and a feedback portion at the other end. In a manufacturing method of transformer 100, which will be described later, coil 10 is arranged in the order of start portion, winding portion, and feedback portion. Both ends of the coil 10 are wound around the base of the terminal 33, and the terminal 33 and the coil 10 are electrically connected. Instead of this embodiment, a winding terminal electrically connected to the terminal 33 may be provided on the bobbin 30, and both ends of the coil 10 may be wound around the winding terminal.

[0021] Either the first coil 11 or the second coil 12 may be a primary winding connected to the input side (power supply side), and either may be a secondary winding connected to the output side. When three or more coils 10 are wound around the bobbin 30 as will be described later in the fifth embodiment, the first coil 11 and the second coil 12 may both be connected to the input side, or both may be connected to the output side.

[0022] The interlayer tape 50 is a member made of an insulating sheet such as a resin. The insulating sheet constituting the interlayer tape 50 of this embodiment is formed by laminating a base layer and an adhesive layer. In the manufacturing process of the transformer 100 described below, the interlayer tape 50 is wound around the bobbin 30 (winding shaft portion 31) so that the adhesive layer is on the radially inner side. This allows the interlayer tape 50 to be wound while adhering to the first coil 11, first creeping tape 61, etc. that are already wound around the winding shaft portion 31. Here, being wound around the bobbin 30 (winding shaft portion 31) includes not only being wound directly around the winding shaft portion 31 of the bobbin 30, but also being wound around the coil 10, tape, etc. wound around the winding shaft portion 31 and then indirectly being wound around the winding shaft portion 31. Other tapes such as a surface creepage tape 60 and a second insulating tape, which will be described later, may also be made of the same insulating sheet as the interlayer tape 50, and may be made up of a base layer and an adhesive layer.

[0023] Here, "the interlayer tape 50 is wound between the first coil 11 and the second coil 12" means that the interlayer tape 50 is disposed over substantially the entire area sandwiched between the first coil 11 and the second coil 12 in the radial direction. Preferably, the interlayer tape 50 is also disposed over substantially the entire area sandwiched between the surface creeping tapes 60 (first surface creeping tape 61 and second surface creeping tape 62 described below) in the radial direction and the area sandwiched between the surface creeping tape 60 and the coil 10. In other words, the interlayer tape 50 is disposed with a shape, dimensions, and position that encompasses substantially the entire area sandwiched between the first coil 11 and the first surface creeping tape 61, and the second coil 12 and the second surface creeping tape 62 in the radial direction. Specifically, the width of the interlayer tape 50 (the length in the winding axis direction) is equal to or greater than the length of the winding shaft portion 31 in the winding axis direction, and the length of the interlayer tape 50 in the length direction (the circumferential direction of the bobbin 30 when the interlayer tape 50 is wound around the winding shaft portion 31) is equal to or greater than the circumferential length of the winding shaft portion 31. The lengthwise dimension and widthwise dimension of the interlayer tape 50 can be any size. That is, if the dimension of the winding shaft portion 31 in the winding axis direction is large, for example, the dimension of the interlayer tape 50 in the width direction (the direction of the winding axis when wound around the winding shaft portion 31) can be larger than the lengthwise dimension (the circumferential direction when wound around the winding shaft portion 31). The same applies to other tapes. In addition, in this embodiment, the first coil 11, the second coil 12 and the surface tape 60 are arranged on the inner side in the winding axis direction of a pair of left and right side end faces 50a, 50a extending in the longitudinal direction of the interlayer tape 50.

[0024] As described above, a portion of the lead-out portion of the coil 10 is disposed along the inner surface 32a of the flange portion 32. Therefore, in the present embodiment, where the first lead-out portion 11a or the second lead-out portion 12a is disposed, the width of the length of the winding shaft portion 31 in the direction of the winding axis over which the tape can be wound (the length in the direction of the winding axis) is shortened by the diameter of the first coil 11 or the second coil 12. Where the first lead-out portion 11a or the second lead-out portion 12a is disposed, the tape is wound while being partially bent radially outward to avoid the first lead-out portion 11a or the second lead-out portion 12a. The bent portion of the tape is not shown in FIGS. 1 and 2 . The bent portion is also not shown in the embodiments described below. In the fifth embodiment, the tape is wound while being bent radially outward to avoid the lead-out portion of the third coil 13 described below.

[0025] The surface creepage tape 60 is a member made of an insulating sheet of resin, etc. The width of the surface creepage tape 60 is preferably equal to or less than half the length of the winding shaft portion 31 in the winding axis direction. The surface creeping tape 60 is wound outside (outside) the coil 10 (first coil 11, second coil 12, or third coil 13 in the fifth embodiment) in the winding axis direction. Here, winding the surface creeping tape 60 outside the coil 10 in the winding axis direction means that the surface creeping tape 60 and the coil 10 are wound in the same layer, and the surface creeping tape 60 is wound outside the coil 10 in the winding axis direction in the layer in which the surface creeping tape 60 and the coil 10 are wound. Winding the coil 10 and the surface creeping tape 60 in the same layer means that the coil 10 and the surface creeping tape 60 partially overlap in the radial direction. In this embodiment, the surface creeping tape 60 is wound outward (left or right) in the winding axis direction of the first coil 11 or outward (left or right) in the winding axis direction of the second coil 12. The surface creeping tape 60 may be wound around all of the above-mentioned locations (both outer sides in the winding axis direction of the first coil 11 and both outer sides in the winding axis direction of the second coil 12) as in this embodiment. Alternatively, the surface creeping tape 60 may be wound around only some of the above-mentioned locations as in a third embodiment described later.

[0026] In order to avoid a short circuit between the first coil 11 and the second coil 12, the first coil 11 and the second coil 12 need to be spaced apart by a certain distance (a specified value) or more at the locations where they are close to each other. In other words, the creepage distance between the first coil 11 and the second coil 12 needs to be maintained at a specified value or more. Here, the creepage distance refers to the minimum length along the surface of the insulator (the creepage tape 60 or the interlayer tape 50) between different coils 10 (for example, the first coil 11 and the second coil 12). In transformer 100, first coil 11 and second coil 12 are close to each other at multiple locations. For example, right end 11d of first winding portion 11b and second lead-out portion 12a are close to each other. Also, left end 12c of second winding portion 12b and first lead-out portion 11a are close to each other. That is, by setting the creepage distance between right end 11d of first winding portion 11b and second lead-out portion 12a and the creepage distance between left end 12c of second winding portion 12b and first lead-out portion 11a to a specified value or greater, the creepage distance between the entire length region of first coil 11 and the entire length region of second coil 12 can be maintained at a specified value or greater. The creepage distance between the entire length regions of the coil 10 is the distance along the surface of the insulator at the point where the coils are closest to each other. For example, as described above, there are multiple points where the first coil 11 and the second coil 12 are close to each other, and the creepage distance between the first coil 11 and the second coil 12 is the distance along the surface of the insulator at one of the multiple points where the first coil 11 and the second coil 12 are closest to each other.

[0027] In this embodiment, the creeping distance between the first coil 11 and the second coil 12 is maintained at a certain value or more by the surface creeping tape 60. Specifically, the lead-out portion of one coil and the winding portion of the other coil, and the winding portion of one coil and the lead-out portion of the other coil are separated by the surface creeping tape 60. In this embodiment, as described above, the first coil 11 and the second coil 12 are close to each other between the right end 11d of the first winding portion 11b and the second lead-out portion 12a, and between the left end 12c of the second winding portion 12b and the first lead-out portion 11a. The creepage distance between the right end 11d of the first winding portion 11b and the second pull-out portion 12a is equal to or greater than the sum of the width of the first creepage tape 61b wound on the right side of the first coil 11 and the thickness (radial length) of the entire interlayer tape 50 wound in one or more layers, as shown in Fig. 1. The creepage distance between the left end 12c of the second winding portion 12b and the first pull-out portion 11a is equal to or greater than the width of the second creepage tape 62a wound on the left side of the second coil 12, as shown in Fig. 2. By making the width of the first surface creepage tape 61b and the second surface creepage tape 62a equal to or greater than the specified value, the creepage distance between the first coil 11 and the second coil 12 can be made equal to or greater than the specified value.

[0028] That at least a portion of the surface creeping tape 60 and the interlayer tape 50 form a single insulating tape (integral insulating tape 40) means that one or more of the surface creeping tapes 60 wound either on the outer side (left or right side) of the winding axis of the first coil 11 or on the outer side (left or right side) of the winding axis of the second coil 12 form a single component with the interlayer tape 50. That the surface creeping tape 60 and the interlayer tape 50 form a single component does not mean that the surface creeping tape 60 and the interlayer tape 50 are formed as separate components and then joined together, but rather that the surface creeping tape 60 and the interlayer tape 50 are a single component formed continuously without any seams.

[0029] By forming the surface creepage tape 60 and the interlayer tape 50 into a single, integrated insulating tape 40, when winding the interlayer tape 50 around the bobbin 30, the surface creepage tape 60 can be wound continuously before or after the interlayer tape 50. In other words, the steps of winding the interlayer tape 50 and the surface creepage tape 60 can be performed at the same time, thereby reducing the number of steps in manufacturing the transformer 100.

[0030] In this embodiment, the surface creeping tape 60 (second surface creeping tape 62) wound around the outside of the second coil 12 in the winding axis direction and the interlayer tape 50 form a single insulating tape (integrated insulating tape 40). More specifically, the second surface creeping tape 62 is disposed at one end of the interlayer tape 50 in the longitudinal direction, outward in the winding axis direction, to form the integrated insulating tape 40. Here, "the surface creeping tape 60 is disposed at one end of the interlayer tape 50 in the longitudinal direction outward in the winding axis direction" means that the surface creeping tape 60 is disposed at one end of the interlayer tape 50 in a position closer to either side in the winding axis direction than the center in the winding axis direction. Preferably, the surface creeping tape 60 is disposed inward in the winding axis direction of two sides (both sides) of the interlayer tape 50 extending in the longitudinal direction of the interlayer tape 50, but this is not limited thereto. A portion of the surface creeping tape 60 may be disposed outward in the winding axis direction of two sides of the interlayer tape 50 extending in the longitudinal direction of the interlayer tape 50. In this embodiment, a second surface tape 62 is arranged on each of the two outer sides in the winding axis direction at one end of the length of the interlayer tape 50, and as shown in Figure 4(a), the inside of the integrated insulating tape 40 in the winding axis direction at one end of the length is hollow.

[0031] Alternatively, the interlayer tape 50 and the second creeping tape 62 may be formed as separate members. In this case, for example, the interlayer tape 50 and the first creeping tape 61 form the integrated insulating tape 40 as a single member.

[0032] By forming the second creeping tape 62 and the interlayer tape 50 into one member as described above, the winding efficiency of the second creeping tape 62 can be improved as follows. The surface creeping tape 60 is preferably wound on the outermost side (closer to the flange 32) of the winding shaft 31 in the winding axis direction. This is to ensure that the area of ​​the winding shaft 31 around which the coil 10 can be wound is sufficiently large. For this reason, when starting to wind the surface creeping tape 60 in the winding step of the surface creeping tape 60 described below, it is necessary to precisely align the winding start position of the surface creeping tape 60 so that the surface creeping tape 60 is wound from the side (outside) sufficiently close to the flange 32 in the winding axis direction. By integrating the second surface creeping tape 62 and the interlayer tape 50 into a single member, the second surface creeping tape 62 is wound immediately after the interlayer tape 50 is wound. By locating the second surface creeping tape 62 at a desired position at one end of the interlayer tape 50, the effort of aligning the winding start position of the second surface creeping tape 62 can be eliminated.

[0033] In this embodiment, the surface creeping tape 60 (first surface creeping tape 61) wound on the outside of the first coil 11 in the winding axis direction and the interlayer tape 50 are separate members. Being separate members means that they may be separated from each other or may be in contact with each other. In this embodiment, the first surface creeping tape 61 and the interlayer tape 50 are adhered to each other via an adhesive layer. The first surface creeping tape 61 and the interlayer tape 50, which are separate members, may be made of the same material or different materials.

[0034] Since the first surface tape 61 and the interlayer tape 50 are separate components, when winding the first coil 11, interference between the interlayer tape 50 and a wire supply section (not shown) for winding the first coil 11 around the winding shaft section 31 can be prevented. Except when using a jig as in the second embodiment described below, it is desirable to wind the first surface-creeping tape 61 before winding the first coil 11. This is because winding the first surface-creeping tape 61 defines an area of ​​the winding shaft 31 around which the first coil 11 can be wound. The first coil 11 is wound around the winding shaft 31 by a wire supply unit such as a nozzle moving around the relatively outer side of the winding shaft 31 in the radial direction, as described below. Therefore, to avoid interference between the wire supply unit and other components, it is desirable that no other components, including the interlayer tape 50, be disposed in the space radially outward of the winding shaft 31 when winding the first coil 11. If the interlayer tape 50 is a separate component from the first surface-creeping tape 61, it is not necessary to dispose the interlayer tape 50 in the space radially outward of the winding shaft 31 when winding the first coil 11. In this way, if the first creeping tape 61 and the interlayer tape 50 are separate members, interference between the wire supply unit and the interlayer tape 50 can be prevented, and the first coil 11 can be wound around the winding shaft unit 31 efficiently.

[0035] Furthermore, because the first creeping tape 61 and the interlayer tape 50 are separate members, in the insulating tape winding step described below, the integrated insulating tape 40 is wound around the bobbin 30 starting with the interlayer tape 50 (interlayer tape portion 41). As will be described later in the second embodiment, when the first creeping tape 61 and the interlayer tape 50 are formed as one member, the winding start positions of the first creeping tapes 61a, 61b on both outer sides in the winding axis direction must be aligned with each other in the circumferential direction and the winding axis direction in order to wind the interlayer tape portion 41 without wrinkles. When the integrated insulating tape 40 is wound around the bobbin 30 starting from the interlayer tape portion 41, the above-mentioned step of aligning the first creeping tape 61 can be omitted.

[0036] In this embodiment, both of the second creeping tapes 62 (second creeping tape 62a, second creeping tape 62b) arranged on the outside of the second coil 12 in the winding axis direction are integrated with the interlayer tape 50, but this is not limited to this. For example, as in a third embodiment described later, the interlayer tape 50 and the creeping tape 60 wound around one side of the first coil 11 or the second coil 12 in the winding axis direction may form an integrated insulating tape 40.

[0037] As described above, a portion of the lead-out portion of the coil 10 is disposed along the inner surface 32a of the flange portion 32. Furthermore, tapes such as the interlayer tape 50 and the surface-creeping tape 60 are wound around the winding shaft portion 31 so as to avoid the portion of the lead-out portion disposed along the inner surface 32a. In Figures 4(a), 4(b), 4(c), 4(d), 5(a), 5(b), 5(c), and 5(d), the portion of the lead-out portion of the coil 10 that is disposed along the inner surface is not shown. Similarly, in the embodiments described below, the portion of the lead-out portion of the coil 10 that is disposed along the inner surface is not shown.

[0038] (bobbin set) The bobbin 30 and the integrated insulating tape 40 according to this embodiment may also be provided as a bobbin set that does not include the coil 10. The bobbin set includes a bobbin 30 extending in the winding axis direction and an insulating tape (integrated insulating tape 40). The integrated insulating tape 40 has a width equal to or greater than the length in the winding axis direction of the winding shaft portion 31 sandwiched between a pair of flange portions 32 spaced apart from each other in the winding axis direction of the bobbin 30. The integrated insulating tape 40 has a creeping tape portion 42 with a length equal to or greater than the circumferential length of the winding shaft portion 31 on the outer side in the width direction at one end in the length direction of the integrated insulating tape 40. Here, the length direction of the integrated insulating tape 40 is the direction perpendicular to the width direction. In this embodiment, the creeping tape portion 42 is provided on both outer sides in the width direction at only one end in the length direction of the integrated insulating tape 40, but this is not limited to this. The creeping tape portion 42 may be provided on both ends in the length direction. Furthermore, the creeping tape portion 42 may be provided on only one outer side in the width direction. The width of each of the surface creepage tape portions 42 is equal to or less than half the width of the interlayer tape portion 41. In other words, the integrated insulating tape 40 has a wide interlayer tape portion 41 that is equal to or greater than the length of the winding axis of the winding shaft portion 31, and a narrow surface creepage tape portion 42 that is less than the width of the interlayer tape portion 41. The length of the interlayer tape portion 41 in the longitudinal direction is equal to or greater than the circumferential length of the winding shaft portion 31. The interlayer tape portion 41 and the surface tape portion 42 are formed from a single member.

[0039] Using a manufacturing method for the transformer 100 described below, the integrated insulating tape 40 and the coil 10 are wound around the winding shaft portion 31 of the bobbin 30. Specifically, the integrated insulating tape 40 is wound so that the interlayer tape portion 41 is positioned between the two coils 10 and the creeping tape portion 42 is positioned outward in the winding axis direction of the coil 10. The integrated insulating tape 40 is wound around the winding shaft portion 31 from either end in the length direction.

[0040] The interlayer tape portion 41 and the creeping tape portion 42 are formed as a single member in the integrated insulating tape 40, so that the interlayer tape portion 41 and the creeping tape portion 42 can be wound continuously. In other words, the integrated insulating tape 40 has a structure that can eliminate the need to wind the interlayer tape portion 41 and the creeping tape portion 42 separately, thereby reducing the number of manufacturing steps for the transformer 100.

[0041] (Transformer manufacturing method) A method for manufacturing the transformer of this embodiment (hereinafter sometimes referred to as the present method) will be described below.

[0042] First, an outline of this method will be described. As described above, the transformer 100 includes the bobbin 30 extending in the winding axis direction, the first coil 11, the second coil 12, and the insulating tape (integrated insulating tape 40). The first coil 11 is wound on the inner side (lower layer side) of the multiple coils 10 wound in layers around the bobbin 30. The second coil 12 is wound on the outer side (upper layer side) of the first coil 11. The integrated insulating tape 40 has an interlayer tape portion 41 wound between the first coil 11 and the second coil 12, and a surface tape portion 42 wound outward in the winding axis direction of the first coil 11 or the second coil 12. The interlayer tape portion 41 and the surface tape portion 42 are formed as a single insulating tape. This method includes a first coil winding process in which the first coil 11 is wound around the winding shaft portion 31, an insulating tape winding process in which a portion of the interlayer tape portion 41 and the surface tape portion 42 are continuously wound around the bobbin 30, and a second coil winding process in which the second coil 12 is wound around the outside of the interlayer tape portion 41.

[0043] Next, the method will be described in detail. First, as shown in FIG. 3(a), the first surface creeping tape 61 is wound on the outer side in the winding axis direction of the winding shaft portion 31. In this embodiment, the first surface creeping tape 61 is wound on both outer sides in the winding axis direction. In this embodiment, the first surface creeping tape 61 is wound in a clockwise direction when the bobbin 30 is viewed from the left side, but this is not limited to this. Not only the surface creeping tape 60, but tapes such as the interlayer tape 50 and the second insulating tape may be wound in a clockwise direction or a counterclockwise direction when the bobbin 30 is viewed from the left side. The tapes may be wound in the same direction as each other, or in different directions. The surface creeping tape 60, such as the first surface creeping tape 61 and the second surface creeping tape 62, may be wound around the winding shaft portion 31 at least once, but may be wound two or more times. Preferably, as shown in Figures 1 and 2, the surface creeping tape 60 is wound so that the overall height (height in the radial direction) of the wound surface creeping tape 60 is equal to or greater than the overall height of the coil 10 wound in the same layer. For example, when the first coil 11 is wound in only one layer, it is preferable that the overall height of the wound first surface creeping tape 61 is equal to or greater than the diameter of the first coil 11.

[0044] In the first coil winding process, as shown in FIG. 3(b), the first coil 11 is wound around the winding shaft 31. Specifically, one end of the first coil 11 at the start of winding is wound around the base of the terminal 33 (e.g., terminal 332) on the left side (upper side of the drawing), and is pulled into the first surface tape 61a while contacting the inner surface 32a of the left flange 32b. The first coil 11 (first start portion 11e) is pulled out to the right side (lower side of the drawing) along the surface of the first surface tape 61a and wound from left to right around the winding shaft 31. In this embodiment, the first coil 11 is wound counterclockwise when viewing the bobbin 30 from the left side, but this is not limiting. The coil 10 may be wound clockwise or counterclockwise when viewing the bobbin 30 from the left side. Different coils 10 may be wound in the same direction or in different directions. The first coil 11 is wound inward in the winding axis direction relative to the first surface creeping tape 61. In this embodiment, the first surface creeping tapes 61 are wound on both outer sides in the winding axis direction, so the first coil 11 is wound between the pair of first surface creeping tapes 61 (first surface creeping tape 61a and first surface creeping tape 61b). In this embodiment, the first coil 11 is wound in only one layer around the winding shaft portion 31, but this is not limited to this. The first coil 11 may be wound in multiple layers around the winding shaft portion 31, as exemplified in a fifth embodiment described below. The first coil 11 wound to the right side is bent leftward and drawn out to the left terminal 33 (for example, terminal 333). The first coil 11 is drawn out radially outward along the inner surface 32a of the left flange portion 32b. One end of the first coil 11 is wound around the base of the terminal 333.

[0045] Generally, a winding device (not shown) is used to wind the coil 10. Specifically, a wire supply unit such as a nozzle for feeding wire in the winding device moves while rotating around a fixed bobbin 30, or the wire supply unit is fixed and the bobbin 30 itself rotates, thereby winding the wire around the outer periphery of the bobbin 30. In this embodiment as well, the coil 10 is wound around the bobbin 30 by the wire supply unit moving around the outside of the bobbin 30 in the radial direction.

[0046] In the insulating tape winding step, the integrated insulating tape 40 is wound. As described above, the integrated insulating tape 40 has an interlayer tape portion 41 and a surface creepage tape portion 42. In this embodiment, the interlayer tape portion 41 is the interlayer tape 50, and the surface creepage tape portion 42 is the second surface creepage tape 62. 4(a), the integrated insulating tape 40 is wound starting from the interlayer tape portion 41, and then a portion of the interlayer tape portion 41 and the surface tape portion 42 are wound continuously. The interlayer tape portion 41 and the surface tape portion 42 are each wound at least once around the winding shaft 31, and may be wound two or more times. "Continuously winding a portion of the interlayer tape portion 41 and the creeping tape portion 42" means that the step of winding at least a portion of the interlayer tape portion 41 and the step of winding the creeping tape portion 42 are carried out consecutively. In the present embodiment, the creeping tape portion 42 is wound after a portion of the interlayer tape portion 41 has been wound, but either the step of winding the interlayer tape portion 41 or the step of winding the creeping tape portion 42 may be carried out first or later. For example, in the case where the first creeping tape 61 and the interlayer tape 50 constitute an integrated insulating tape 40, the interlayer tape 50 is wound after the creeping tape portion 42 has been wound. In this embodiment, after a portion of the interlayer tape portion 41 is wound as shown in Fig. 4(b), the second coil 12 is pulled into the winding shaft portion 31. After the second coil 12 is pulled into the winding shaft portion 31, the remaining portion of the interlayer tape portion 41 is wound as shown in Fig. 4(c), and then the surface tape portion 42 is continuously wound as shown in Fig. 4(d).

[0047] When the second creeping tape 62 is wound after the second coil 12 is pulled into the winding shaft unit 31, a wire supply unit (not shown) for winding the second coil 12 is disposed radially outside the winding shaft unit 31 while the second creeping tape 62 is being wound. To avoid interference between the wound second creeping tape 62 and the wire supply unit, it is preferable to dispose the wire supply unit in the space radially outside the winding shaft unit 31, between the space radially outside the wound second creeping tape 62a and the space radially outside the wound second creeping tape 62b.

[0048] In the second coil winding process, the second coil 12 is wound around the bobbin 30. As shown in FIG. 4(b), one end of the second coil 12 is wound around the base of the right-side terminal 33 (e.g., terminal 336). The second coil 12 is arranged along the inner surface 32a of the right-side flange 32c and pulled into the interlayer tape portion 41. As shown in FIG. 5(a), the second coil 12 is wound in the region inside the flanges 32b, 32c and the second creeping tape 62 as viewed in the winding axis direction. In this embodiment, the second creeping tape 62 is wound on both outer sides in the winding axis direction, and the second coil 12 is wound from the right side (lower side in the drawing) to the left side (upper side in the drawing) in the region between the pair of second creeping tapes 62a, 62b. As shown in FIG. 5(c), the second coil 12 wound to the left side is bent to the right at the boundary 12g, and the other end of the second coil 12 is wound around the base of the right terminal 33 (for example, terminal 337).

[0049] 5(b) and 5(d), after the second coil 12 is wound, a peripheral tape 70 (described later) is disposed and wound on top of the second coil 12. The peripheral tape 70 may be wound around the winding shaft portion 31 once, but may also be wound around the winding shaft portion 31 two or more times.

[0050] 1, a portion of the second coil 12 (second start portion 12e) is disposed between the interlayer tape 50 and a surface creeping tape 60 (second surface creeping tape 62b) formed of a single member together with the interlayer tape 50 and wound outwardly of the second coil 12 in the winding axis direction. Specifically, the portion of the second coil 12 is disposed between the interlayer tape 50 and the surface creeping tape 60 wound on the same side as the side on which one end of the second coil 12 is bound. The second coil 12 is wound as follows, so that the second start portion 12e is positioned between the interlayer tape 50 and the second creeping tape 62b. When the interlayer tape portion 41 of the integrated insulating tape 40 is wound partway as shown in FIG. 4(b), the second coil 12, one end of which is wound around the terminal 33, is pulled inward in the winding axis direction onto the interlayer tape portion 41. As shown in FIG. 4(c), the integrated insulating tape 40 is wound so that the creeping tape portion 42 (second creeping tape 62b) is positioned on the upper layer side of the second coil 12 that has been pulled inward in the winding axis direction. As a result, the second start portion 12e is positioned between the interlayer tape 50 and the second creeping tape 62b.

[0051] The second start portion 12e of the second coil 12 is disposed substantially parallel to the winding shaft portion 31, but in order to wind the second coil 12 around the winding shaft portion 31, the second coil 12 needs to be bent in either direction in the circumferential direction as shown in FIG. 4(d). That is, the second coil 12 is bent at a bend portion 12j between the second start portion 12e and the second winding portion 12b. By disposing the second creeping tape 62b on the upper layer side of the second start portion 12e, the second start portion 12e is sandwiched and fixed between the second creeping tape 62b and the interlayer tape 50. This allows the second coil 12 to be easily bent at the bend portion 12j.

[0052] The transformer 100 has a second insulating tape (in this embodiment, the outer peripheral tape 70) that is wound around the outer (upper) side of a portion of the second coil 12 and includes a wide portion having a width equal to or greater than the length of the winding shaft portion 31 of the bobbin 30 in the winding axis direction. The second insulating tape may be wound around the upper layer of a portion of the second coil 12, or may be wound around the upper layer of the entire second coil 12. The wide portion is a wide, solid portion of the second insulating tape. The width of the wide portion refers to the longest length of the wide portion in the winding axis direction. The length of the wide portion in the longitudinal direction is equal to or greater than the circumferential length of the winding shaft portion 31, and preferably equal to or greater than the circumferential length of the second coil 12 wound around the lower layer of the second insulating tape. In this embodiment, the entire second insulating tape (peripheral tape 70) (including the portion where the notch 71 described later is formed) is the wide portion, but this is not limited to this. It is sufficient that only a portion of the second insulating tape is the wide portion. For example, when the second insulating tape is a partition tape 80 wound between the first and second layers of the second coil 12 as in the fifth embodiment described later, the partition tape 80 may have a surface tape portion 83 in addition to the partition portion 81, which is the wide portion.

[0053] As shown in Figure 5(b), one end in the longitudinal direction of the wide portion is provided with a notch 71. The notch 71 is a missing portion provided on one side in the winding axis direction, closer to the outside. Specifically, the notch 71 is provided on one of both sides in the winding axis direction, on the side where one end of the winding end of the second coil 12 wound in the lower layer of the outer peripheral tape 70 is located (the upper side of the paper in the figure). In this embodiment, the cutout 71 has a rectangular shape obtained by cutting out a corner of one end of the peripheral tape 70 in the longitudinal direction. In this case, the length of the cutout 71 in the winding axis direction is preferably equal to or greater than the sum of the width of the second surface tape 62 and the diameter of the second coil 12. Furthermore, the length of the cutout 71 in the winding axis direction is preferably equal to or less than half the width of the wide portion. The length of the cutout 71 in the longitudinal direction is preferably equal to or greater than the diameter of the second coil 12.

[0054] The notch 71 is not limited to being provided at a corner of the wide portion as exemplified in this embodiment. For example, the notch 71 may be formed in a shape recessed inward in the longitudinal direction on one end side of the peripheral tape 70 in the longitudinal direction (the side extending in the winding axis direction). In this case, the notch 71 is formed inward in the winding axis direction from the end of that side of the peripheral tape 70. Preferably, the notch 71 is provided inward in the winding axis direction from the portion of the peripheral tape 70 that contacts the second creeping tape 62. In this case, the depth (circumferential length) and width (length in the winding axis direction) of the notch 71 are preferably equal to or greater than the diameter of the second coil 12. Another example of the shape of the cutout 71 is one in which a side extending in the length direction of the peripheral tape 70 at one end of the peripheral tape 70 is recessed inward in the width direction. The cutout 71 is formed inward in the length direction from one end of the side. In this case, the depth of the cutout 71 (length in the winding axis direction) is preferably equal to or greater than the sum of the width of the second surface tape 62 and the diameter of the second coil 12. Furthermore, the width (length in the length direction) of the cutout 71 is preferably equal to or greater than the diameter of the second coil 12.

[0055] The second coil 12 is disposed across the inside (lower layer side) and outside (upper layer side) of the second insulating tape (peripheral tape 70) through the cutout 71. That is, as shown in Fig. 2, a part of the second coil 12 (such as the second winding portion 12b) is disposed below the peripheral tape 70 (wide portion), and another part of the second coil 12 (such as the second return portion 12f) is disposed above the peripheral tape 70 (wide portion). Also, as shown in Fig. 5(c), the boundary portion 12g between the second winding portion 12b and the second return portion 12f is disposed within the cutout 71 when viewed from the radial direction.

[0056] The outer tape 70 having the notch 71 is wound in the following manner. When the second coil 12 is wound from the right side (lower side on the paper) to the left side (upper side on the paper), the outer peripheral tape 70 is arranged between the flange portions 32 on both sides so that the notch 71 is located on the left side as shown in Fig. 5(b). Furthermore, when viewed in the radial direction, the outer peripheral tape 70 is arranged so that the portion where the second coil 12 is folded back (boundary portion 12g (see Fig. 5(c))) is located within the notch 71. Specifically, the outer peripheral tape 70 is arranged so that the terminal 33 (e.g., terminal 337) around which one end of the winding end of the second coil 12 is wound partially overlaps with the notch 71 when viewed in the winding axis direction. After the outer peripheral tape 70 is placed, the second coil 12, which is placed within the cutout portion 71 when viewed in the radial direction, is bent toward the terminal 337 at the boundary portion 12g. The second coil 12 (second return portion 12f) is placed along the outside of the outer peripheral tape 70 up to the right flange portion 32c. Furthermore, the second coil 12 is pulled out radially outward along the inner surface 32a of the flange portion 32c as described above, and then wound around the terminal 337. The outer peripheral tape 70 is wound around the second coil 12, including the second return portion 12f.

[0057] The outer peripheral tape 70 is wound around the upper layer of the second winding portion 12b. A partial length region of the winding end of the second winding portion 12b is fixed by the outer peripheral tape 70, which makes it easy to bend the second coil 12 at the boundary portion 12g and pass it over to the terminal 337 side. In addition, by arranging the second winding portion 12b on the lower side of the outer tape 70 and the second return portion 12f on the upper side of the outer tape 70, loosening of the winding of a partial length region at the end of the winding of the second winding portion 12b and the second return portion 12f is prevented.

[0058] In this embodiment, the second insulating tape is the outer peripheral tape 70, but the second insulating tape is not limited to the outer peripheral tape 70. For example, when the second coil 12 is wound in two or more layers as in the fifth embodiment, the second insulating tape is a partition tape 80 wound between the first and second layers of the second coil 12. Furthermore, when the third coil 13 is wound on the upper side of the first layer of the second coil 12, the second insulating tape is a second interlayer tape 52, which will be described later.

[0059] Second Embodiment This embodiment differs from the first embodiment in that the first creepage tape 61 also constitutes the integrated insulating tape 40 as a single member together with the interlayer tape 50 . Similar to the transformer 100 of the first embodiment, the transformer 100 of this embodiment has a bobbin 30, a first coil 11, a second coil 12, an interlayer tape 50, and a surface creepage tape 60. The first coil 11 is wound in a lower layer of the multiple coils 10 wound in layers around the bobbin 30. The second coil 12 is wound in an upper layer above the first coil 11. The interlayer tape 50 is wound between the first coil 11 and the second coil 12. The surface creepage tape 60 is wound outward of the first coil 11 or the second coil 12 when viewed in the winding axis direction. At least a portion of the surface creepage tape 60 and the interlayer tape 50 form a single insulating tape (integrated insulating tape 40). Specifically, the surface creeping tape 60 (second surface creeping tape 62) wound around the outside of the second coil 12 in the winding axis direction and the interlayer tape 50 form a single insulating tape (integrated insulating tape 40). Also, the surface creeping tape 60 (second surface creeping tape 62) wound around the outside of the first coil 11 in the winding axis direction and the interlayer tape 50 form a single insulating tape (integrated insulating tape 40). That is, as shown in FIG. 8(a), the inside of the integrated insulating tape 40 in the winding axis direction is hollow at both longitudinal ends. In this embodiment, the first surface creeping tape 61 is arranged on both outer sides of the first coil 11 in the winding axis direction, and the second surface creeping tape 62 is arranged on both outer sides of the second coil 12 in the winding axis direction, but this is not limited to this. The surface creeping tape 60 may be arranged only on the outer side of one of the first coil 11 or the second coil 12 in the winding axis direction. The width of the first surface creeping tape 61 and the width of the second surface creeping tape 62 may be the same, or one may be larger and the other may be smaller. Furthermore, the length in the longitudinal direction of the first surface creeping tape 61 and the length in the longitudinal direction of the second surface creeping tape 62 may be the same, or one may be larger and the other may be smaller.

[0060] By configuring the integrated insulating tape 40 as described above, the first creeping tape 61, the interlayer tape 50, and the second creeping tape 62 can be wound continuously in the insulating tape winding step described below, which allows the number of manufacturing steps to be reduced.

[0061] 6(b), in this embodiment, the transformer 100 has a second insulating tape (peripheral tape 70) wound around the upper layer side of a portion of the second coil 12 and including a wide portion having a width equal to or greater than the length in the winding axis direction of the winding shaft portion 31 of the bobbin 30. A notch 71 (see FIG. 5(b)) is provided at one end in the longitudinal direction of the wide portion, and the second coil 12 is disposed on both the lower layer side and the upper layer side of the peripheral tape 70 through the notch 71.

[0062] In this embodiment, as shown in Figure 6(b), a portion of the second coil 12 (second starting portion 12e) is arranged between the interlayer tape 50 and a surface tape (second surface tape 62b) formed from a single member with the interlayer tape 50 and wound outward in the winding axis direction of the second coil 12.

[0063] The transformer 100 of this embodiment is manufactured as follows. As with the first embodiment, the manufacturing method of the transformer 100 of this embodiment includes a first coil winding process in which the first coil 11 is wound around the winding shaft portion 31, an insulating tape winding process in which a portion of the interlayer tape portion 41 and the surface tape portion 42 are continuously wound around the bobbin 30, and a second coil winding process in which the second coil 12 is wound around the outside of the interlayer tape portion 41.

[0064] First, as shown in Fig. 7(a), one end of first coil 11 is wound around the base of terminal 332. First coil 11 is pulled into winding shaft portion 31 along inner surface 32a of flange portion 32b. Specifically, first coil 11 is pulled inward in the winding axis direction by a distance equal to or greater than the width (length in the winding axis direction) of jig 200, which will be described later. A wire supply portion located at the tip of first coil 11 is not shown in the figure. Next, as shown in FIG. 7(b), jig 200 is placed on the outer side of winding shaft portion 31 in the winding axis direction. In this embodiment, jigs 200 are placed on both outer sides of winding shaft portion 31 in the winding axis direction. When flange 32 and first coil 11 are to be separated only on one outer side of winding shaft portion 31 in the winding axis direction, as in a third embodiment described below, jig 200 may be placed on the side where flange 32 and first coil 11 are to be separated. In addition, jig 200 is placed on the upper layer side of first start portion 11e.

[0065] The jig 200 is a tool for defining an area of ​​the winding shaft 31 where the first coil 11 is wound. The jig 200 is detachably attached to the winding shaft 31 and holds the first lead-out portion 11a of the first coil 11. The length of the first coil 11 held by the jig 200 becomes the first start portion 11e (see FIG. 6(b)), and the portion of the first coil 11 inside the jig 200 in the winding axis direction becomes the first winding portion 11b. In other words, the jig 200 separates the first coil 11 from one end of the winding shaft 31 in the winding axis direction. Specifically, the jig 200 separates the first coil 11 from the flange portion 32. The width of the jig 200 is preferably equal to or greater than the width of the first surface-creeping tape 61. In this embodiment, the jig 200 has a shape and dimensions that allow it to be disposed around substantially the entire length of the winding shaft 31, but is not limited to this. For example, jigs 200 may be arranged discretely around part of the periphery of winding shaft portion 31, so that first coil 11 is spaced apart from one end of winding shaft portion 31 in the direction of the winding axis. Jig 200 is made of a material, such as metal or resin, that has sufficient rigidity to separate first coil 11 from one end in the winding direction of winding shaft portion 31. Examples of jig 200 include a clamp structure in which winding shaft portion 31 is sandwiched between two arc-shaped metal members, or a tape-shaped member that is wound around winding shaft portion 31.

[0066] Once the jig 200 is in place, the first coil winding step is performed. The first coil 11 is wound around the inside of the jig in the winding axis direction, as shown in Fig. 7(b). Once the first coil 11 is wound, the jig 200 is removed.

[0067] After the first coil 11 is wound, an insulating tape winding step is carried out. When the jig 200 is removed, the integrated insulating tape 40 is wound around the bobbin 30 as shown in FIG. 8(a). The integrated insulating tape 40 is wound in the order of the surface creepage tape portion 42a (first surface creepage tape 61), the interlayer tape portion 41 (interlayer tape 50), and the surface creepage tape portion 42b (second surface creepage tape 62). The first surface creepage tape 61 is wound around the region of the winding shaft portion 31 where the jig 200 was located. In other words, the first surface creepage tape 61 is wound outward of the first coil 11 in the winding axis direction.

[0068] 8(a), one end of the first coil 11 is disposed radially outward from the winding shaft portion 31 until at least a portion of the first creeping tape 61 has been wound. To avoid interference between the first creeping tape 61 and a wire supply portion for winding the first coil 11, the wire supply portion is preferably disposed radially outward from the first winding portion 11b. After at least a portion of the first creeping tape 61 has been wound, the first coil 11 wound on the rightmost side (lower side of the drawing) of the first winding portion 11b is bent to the left (upper side of the drawing) as shown in Fig. 8(b). The first coil 11 is arranged along the inner surface 32a of the flange portion 32b, pulled out radially outward, and wound around the base of the terminal 333. After one end of the first coil 11 is wound around the terminal 333, the remaining part of the first surface tape 61, the interlayer tape 50 and the second surface tape 62 are wound continuously in this order. By winding the first coil 11 and the integrated insulating tape 40 as described above, in this embodiment, the first starting portion 11e is positioned between the winding shaft portion 31 and the first surface tape 61a, as shown in Figure 6(b).

[0069] The winding start positions of the first surface creeping tapes 61a and 61b may be determined taking into consideration the winding position of the interlayer tape portion 41. For example, the winding start positions of the first surface creeping tape 61a and the first surface creeping tape 61b need to be aligned with each other in the circumferential direction. Specifically, the winding start position of the first surface creeping tape 61a or the first surface creeping tape 61b is a position that is circumferentially separated from the intended winding position of the interlayer tape portion 41 by the length of the first surface creeping tape 61a or the first surface creeping tape 61b. The winding start positions of the first surface creeping tape 61a and the first surface creeping tape 61b also need to be aligned in the direction of the winding axis. Specifically, the distance between the winding start position of the first surface creeping tape 61a and the winding start position of the first surface creeping tape 61b should be set in the direction of the winding axis to match the width of the interlayer tape portion 41. By aligning the winding start positions of the first surface creeping tape 61a and the first surface creeping tape 61b in the circumferential direction and the winding axis direction in this manner, the interlayer tape portion 41 can be wound without wrinkles.

[0070] As in the first embodiment, after the integrated insulating tape 40 is wound, a second coil winding step is performed in which the second coil 12 is wound on the upper layer side of the interlayer tape 50. After the second coil 12 is wound, an outer tape 70 having a notch 71 is wound around the winding shaft portion 31 as the second insulating tape.

[0071] Third Embodiment This embodiment differs from the second embodiment in that the first surface creeping tape 61 and the second surface creeping tape 62 are arranged only on the outside of one side of the coil 10 in the winding axis direction.

[0072] The transformer 100 of this embodiment includes a bobbin 30, a first coil 11, a second coil 12, an interlayer tape 50, and a surface tape 60, similar to the transformer 100 of the first embodiment. 9(a), both ends of first coil 11 are extended to one side in the winding axis direction (left side, upper side on the paper), and both ends of second coil 12 are extended to the other side in the winding axis direction (right side, lower side on the paper). Furthermore, as shown in FIGS. 10(a) and 10(b), creeping tape 60 is wound around at least the other side (right side) of first coil 11 and at least one side (left side) of second coil 12.

[0073] As in this embodiment, by arranging the surface tape 60 only on the outside of one side of the coil 10 in the winding axis direction, a larger area of ​​the winding shaft portion 31 can be secured for winding the coil 10 than when the surface tape 60 is arranged on both outsides of the coil 10 in the winding axis direction. Furthermore, when the first creeping tapes 61 are disposed on both outer sides of the first coil 11 in the winding axis direction, it is necessary to align the winding start positions between the pair of first creeping tapes 61, 61 in the circumferential direction and in the winding axis direction, as described above. By winding the first creeping tape 61 only on one outer side of the first coil 11 in the winding axis direction as in this embodiment, this alignment work can be omitted. This can increase the winding efficiency of the integrated insulating tape 40.

[0074] In this embodiment, the second surface tape 62 wound outward in the winding axis direction of the second coil 12 and the interlayer tape 50 form a single-piece integrated insulating tape 40, and the first surface tape 61 wound outward in the winding axis direction of the first coil 11 and the interlayer tape 50 form a single-piece integrated insulating tape 40. More specifically, the surface creeping tape 60 (first surface creeping tape 61) wound around the other side (right side) of the first coil 11, the surface creeping tape 60 (second surface creeping tape 62) wound around one side (left side) of the second coil 12, and the interlayer tape 50 form a single insulating tape (integrated insulating tape 40). That is, in this embodiment, as shown in Fig. 9(b), the integrated insulating tape 40 has a rectangular interlayer tape portion 41, and surface creeping tape portions 42 (surface creeping tape portion 42a and surface creeping tape portion 42b) are provided at diagonal positions of the interlayer tape portion 41, extending in the length direction.

[0075] In this embodiment, the first surface-creeping tape 61 is wound only on the other side (right side) of the first coil 11, and the second surface-creeping tape 62 is wound only on one side (left side) of the second coil 12. Instead of this embodiment, as shown in the first and second embodiments, the tapes may be wound on both one and the other sides of the coil 10 (both sides in the winding axis direction). Alternatively to this embodiment, the first surface creeping tape 61 and the interlayer tape 50 may be separate members, or the second surface creeping tape 62 and the interlayer tape 50 may be separate members. That is, only the second surface creeping tape 62 and the interlayer tape 50, or only the first surface creeping tapes 61 and 50 may be one member.

[0076] Since the first creeping tape 61, the interlayer tape 50, and the second creeping tape 62 are one component, these tapes can be wound in one step in the manufacturing method of the transformer 100, which will be described later.

[0077] 10(a), in this embodiment, the transformer 100 has a second insulating tape (peripheral tape 70) wound around the upper layer side of a portion of the second coil 12 and including a wide portion having a width equal to or greater than the length in the winding axis direction of the winding shaft portion 31 of the bobbin 30. A notch 71 is provided at one end in the longitudinal direction of the wide portion, and the second coil 12 is disposed on both the lower layer side and the upper layer side of the peripheral tape 70 through the notch 71.

[0078] The manufacturing process of the transformer 100 of this embodiment includes a first coil winding step, an insulating tape winding step, and a second coil winding step, similar to the first and second embodiments. Specifically, the transformer 100 is manufactured as follows. First, jig 200 (see FIG. 7(b)) is placed on the outer side of winding axis direction of winding shaft portion 31. In this embodiment, jig 200 is placed only on the other side (right side) of winding shaft portion 31. This is because in this embodiment, the other side of first coil 11 and flange portion 32c need to be spaced apart. Once the jig 200 is placed, the first coil winding process is performed. The first coil 11 is wound around an area of ​​the winding shaft portion 31 where the jig 200 is not placed. As shown in Fig. 9(b) , both ends of the first coil 11 are wound around the base of the terminal 33 (terminals 332 and 333 in this embodiment) on one side (the left side). After the first coil 11 is wound, the insulating tape winding process is carried out. First, the surface creepage tape portion 42a (first surface creepage tape 61) of the integrated insulating tape 40 is wound between the first coil 11 and the flange portion 32c. Next, the interlayer tape portion 41 is wound on top of the first coil 11, and then the surface creepage tape portion 42b (second surface creepage tape 62) is wound on the left side of the winding shaft portion 31. After the second surface creeping tape 62 is wound, a second coil winding step is performed, in which the second coil 12 is wound on the upper layer of the interlayer tape portion 41. The second coil 12 is wound in the region inside the pair of flange portions 32, excluding the region where the second surface creeping tape 62 is wound. In this embodiment, the second coil 12 is wound between the flange portion 32c and the second surface creeping tape 62. An outer circumferential tape 70 is wound around the outer periphery of the second coil 12 as a second insulating tape, similar to the first embodiment.

[0079] <Fourth embodiment> This embodiment differs from the first embodiment in that terminal 33 is provided on only one side of bobbin 30 in the winding axis direction, and first coil 11 and second coil 12 are pulled out to the same side (the side in the winding axis direction where terminal 33 is located).

[0080] Like the transformer 100 of the first embodiment, the transformer 100 of this embodiment also has a bobbin 30 extending in the winding axis direction, a first coil 11 wound on the lower layer side, a second coil 12 wound on the upper layer of the first coil 11, an interlayer tape 50 wound between the first coil 11 and the second coil 12, and one or more surface tapes 60. In this embodiment, the second surface tape 62 wound around the outer side of the winding axis direction of the second coil 12 and the interlayer tape 50 form a single integrated insulating tape 40, and the first surface tape 61 wound around the outer side of the winding axis direction of the first coil 11 and the interlayer tape 50 are separate components.

[0081] The bobbin 30 has a plurality of terminals 33 on one side in the winding axis direction. In this embodiment, as shown in FIG. 11(a), the bobbin 30 has four terminals 33 (terminals 331 to 334) on the left side. As shown in FIG. 11(b), the terminals 33 have a surface (vertical surface 33b) perpendicular to the winding axis direction. The transformer 100 is placed on the mounting substrate so that the vertical surface 33b is grounded to the mounting substrate. In other words, the transformer 100 in this embodiment is a vertical transformer placed so that the winding axis portion is perpendicular to the mounting substrate. The terminals 33 are not limited to a terminal shape for planar mounting and may be pin-shaped.

[0082] In this embodiment, as shown in FIG. 11(a), both ends of first coil 11 (first lead portion 11a) and both ends of second coil 12 (second lead portion 12a) are led out to one side in the winding axis direction (upper side in the drawing). In this embodiment, the "one side" refers to the side in the winding axis direction where terminal 33 is located, and is referred to as the left side of transformer 100 in this embodiment. The left side of transformer 100 in this embodiment corresponds to the left side in the drawing in FIG. 11(b). First lead portion 11a and second lead portion 12a, which are led out to the same side in the winding axis direction, maintain a creepage distance of at least a specified value between them in the winding direction of winding shaft portion 31. The surface creeping tape 60 is wound around one side (left side) of the first coil 11 and the second coil 12 and the other side (right side) of the first coil 11 or the second coil 12. In this embodiment, the surface creeping tape 60 is wound around both sides of the first coil 11 and the second coil 12 in the winding axis direction, but this is not limited to this. The first surface creeping tape 61 may not be arranged on the other side (right side) of the first coil 11, and the first surface creeping tape 61 may be arranged only on one side (left side). Furthermore, the second surface creeping tape 62 may not be arranged on the other side (right side) of the second coil 12, and the second surface creeping tape 62 may be arranged only on one side (left side). However, if the first surface creeping tape 61b is not arranged on the other side of the first coil 11, the second surface creeping tape 62b is wound around the other side of the second coil 12. Similarly, if the second surface creeping tape 62b is not wound around the other side of the second coil 12, the first surface creeping tape 61b is wound around the other side of the first coil 11. That is, the surface tape 60 is wound around at least one of the other side of the first coil 11 and the other side of the second coil 12.

[0083] In this embodiment, the first creeping tape 61 and the interlayer tape 50 are separate members, and the interlayer tape 50 and the second creeping tape 62 form a single, integrated insulating tape 40, but this is not limiting. For example, instead of this embodiment, as in the second embodiment, the first creeping tape 61, the interlayer tape 50, and the second creeping tape 62 may all be a single member to form the integrated insulating tape 40. Alternatively, the first creeping tape 61 and the interlayer tape 50 may form a single, integrated insulating tape 40, and the interlayer tape 50 and the second creeping tape 62 may be separate members.

[0084] When the first coil 11 and the second coil 12 are pulled out on the same side in the winding axis direction as in this embodiment, the width of the surface creeping tape 60 can be set as follows. That is, the total length in the winding axis direction of the surface creeping tape 60 arranged on the other side (right side) of the first coil 11 or the second coil 12 is equivalent to the length in the winding axis direction of each of the surface creeping tapes 60 arranged on one side (left side) of the first coil 11 or the second coil 12. That is, the total width of the first surface creeping tape 61b and the second surface creeping tape 62b is equivalent to the respective widths of the first surface creeping tape 61a and the second surface creeping tape 62a. Here, "equivalent" means that the total width of the first surface creeping tape 61b and the second surface creeping tape 62b is more than half the width of the first surface creeping tape 61a or the second surface creeping tape 62a and is not more than twice the width of the first surface creeping tape 61a or the second surface creeping tape 62a. When the surface creeping tape 60 is not wound around the other side (right side) of the first coil 11 and is wound only around the other side (right side) of the second coil 12, the sum of the widths of the first surface creeping tape 61b and the second surface creeping tape 62b is the width of the second surface creeping tape 62b. Similarly, when the surface creeping tape 60 is not wound around the other side of the second coil 12 and is wound only around the other side of the first coil 11, the sum of the widths of the first surface creeping tape 61b and the second surface creeping tape 62b is the width of the first surface creeping tape 61b.

[0085] In this embodiment, as shown in FIG. 11B, the coils 10 are not only adjacent between the lead-out portion of one coil 10 and the wound portion of the other coil 10 as in the first embodiment, but also adjacent between the ends (right ends) of the wound portions of the coils 10 on the other side. Specifically, the first coil 11 and the second coil 12 are also adjacent between the right end 11d of the first wound portion 11b and the right end 12d of the second wound portion 12b. The creeping distance between the right end 11d of the first wound portion 11b and the right end 12d of the second wound portion 12b is at least the sum of the widths of the first creeping tape 61b, the second creeping tape 62b, and the winding thickness of the interlayer tape 50. In other words, to maintain a sufficient creeping distance between the right end 11d of the first coil 11 and the right end 12d of the second coil 12, it is sufficient to set the sum of the widths of the first creeping tape 61b and the second creeping tape 62b to a specified value or greater.

[0086] In this embodiment, the width of the first surface creeping tape 61b and the width of the second surface creeping tape 62b are equal, but this is not limited to this. The width of the first surface creeping tape 61b may be longer or shorter than the width of the second surface creeping tape 62b. The embodiment in which the width of the first surface creeping tape 61b is longer or shorter than the width of the second surface creeping tape 62b also includes the embodiment in which either the first surface creeping tape 61b or the second surface creeping tape 62b is not provided, as described above. For example, the width of the surface tape 60 wound around the other side (right side) of the coil 10 having the longer winding width of the first coil 11 or the second coil 12 may be shorter than the width of the surface tape 60 wound around the other side (right side) of the coil 10 having the shorter winding width. The winding width refers to the length of the region of the winding shaft portion 31 required for winding the coil 10 in the winding axis direction. Specifically, the winding width is the product of the winding pitch of the coil 10 and the number of winding turns. When the coil 10 is densely wound, the winding pitch of the coil 10 is equal to the wire diameter of the coil wire. By arranging a surface tape 60 with a shorter width in the same layer as the coil 10 requiring a larger winding width, or by not arranging a surface tape 60 at all, the overall dimension of the bobbin 30 in the winding axis direction can be reduced. In other words, if the dimension of the bobbin 30 in the winding axis direction is predetermined, a larger length region in the winding axis direction for winding the coil 10 can be secured.

[0087] 11(b), the transformer 100 has a second insulating tape (peripheral tape 70) that is wound around the upper layer of a portion of the second coil 12 and includes a wide portion that has a width equal to or greater than the length of the winding axis direction of the winding shaft portion 31 of the bobbin 30. A notch 71 (see FIG. 5(b)) is provided at one end in the longitudinal direction of the wide portion, and the second coil 12 is disposed across the lower and upper layers of the peripheral tape 70 through the notch 71. 5(b) in the first embodiment is provided on the left side (upper side in the drawing) of one end of the peripheral tape 70, whereas the notch 71 in this embodiment is provided on the right side (lower side in the drawing) of one end of the peripheral tape 70. In this embodiment, one end of the winding end of the second coil 12 wound on the lower layer side of the peripheral tape 70 is located on the right side, and the position of the notch 71 corresponds to the position of the winding end.

[0088] A part of the second coil 12 (second start portion 12e (see FIG. 4(d) and not shown in FIG. 11(b))) is disposed between the interlayer tape 50 and a surface creeping tape 60 (second surface creeping tape 62) formed of a single member together with the interlayer tape 50 and wound outward in the winding axis direction of the second coil 12. 4(d) in the first embodiment is located between the interlayer tape 50 and the second creeping tape 62b on the right side, but the second starting portion in this embodiment is located between the interlayer tape 50 and the second creeping tape 62a on the left side. This is because in this embodiment, the second coil 12 is wound around the terminal 331 provided on the left flange 32b, is pulled into the winding shaft 31 from the left side along the inner surface 32a of the flange 32b, and is routed along the upper surface of the interlayer tape 50 to form the second wound portion 12b.

[0089] The manufacturing method of the transformer 100 in this embodiment includes a first coil winding step, an insulating tape winding step, and a second coil winding step, similar to the first and second embodiments. Specifically, the transformer 100 is manufactured as follows. First, the first surface creeping tape 61 is wound around the winding shaft portion 31, near the outer side in the winding axis direction. After the first surface creeping tape 61 is wound, the first coil winding step is carried out. The first coil 11 is wound around the inner side in the winding axis direction of the first surface creeping tape 61. As shown in FIG. 11(a), both ends of the first coil 11 are wound around one (left side) terminal 33 (terminals 332 and 333 in this embodiment). After the first coil 11 is wound, the insulating tape winding step is carried out. After the interlayer tape 50 of the integrated insulating tape 40 is wound on the upper layer of the first coil 11, the second creeping tape 62 is wound thereon. After the second surface-creeping tape 62 is wound, a second coil winding step is performed, in which the second coil 12 is wound on the upper layer of the interlayer tape 50. The second coil 12 is wound on the inside in the winding axis direction of the second surface-creeping tape 62. Both ends of the second coil 12 are wound around one (left side) terminal 33 (terminals 331 and 334 in this embodiment). As in the first embodiment, an outer circumferential tape 70 is wound around the outer periphery of the second coil 12 as a second insulating tape.

[0090] Fifth Embodiment A transformer 100 according to the fifth embodiment will be described with reference to FIGS. 12(a) to 12(c), 13(a) to 13(c), 14(a) to 14(d), 15, and 16. FIG. This embodiment differs from the first embodiment in that the transformer 100 has a third coil 13, and that the second coil 12 and the third coil 13 are wound in two layers. Similar to the transformer 100 of the first embodiment, the transformer 100 of this embodiment includes a bobbin 30, a first coil 11, a second coil 12, an interlayer tape 50, and a surface tape 60. The transformer 100 further includes a third coil 13, a partition tape 80, and a second interlayer tape (second interlayer tape 52). 15 and 16, the third coil 13 is wound in layers on the upper side of the second coil 12. A surface creeping tape 60 (third surface creeping tape 63) is wound on both outer sides of the third coil 13 in the winding axis direction. The partition tape 80 is wound between the layers of the coil 10, which is wound in multiple layers. Specifically, in the second coil 12 and the third coil 13, which are wound in two layers, the partition tape 80 is wound between the first and second layers.

[0091] Just as the interlayer tape 50 is wound between the first coil 11 and the second coil 12, a second interlayer tape 52 is wound between the second coil 12 and the third coil 13. In this embodiment, the second interlayer tape 52 and the third creeping tape 63 form a second integrated insulating tape (second tape 90) of one component. Furthermore, in this embodiment, as in the first embodiment, the first surface-shielding tape 61 and the interlayer tape 50 are separate components, and the interlayer tape 50 and the second surface-shielding tape 62 form a single, integrated insulating tape 40 (first tape 40). Alternatively to this embodiment, the first surface-creeping tape 61 and the interlayer tape 50 may form the first tape 40, and the second surface-creeping tape 62 and the second interlayer tape 52 may form the second tape 90. Furthermore, the first surface-creeping tape 61, the interlayer tape 50, and the second surface-creeping tape 62 may form the first tape 40 as a single component, or the second surface-creeping tape 62, the second interlayer tape 52, and the third surface-creeping tape 63 may form the second tape 90 as a single component.

[0092] In this embodiment, as shown in Figure 15, a portion of the second coil 12 (second starting portion 12e) is arranged between the interlayer tape 50 and a surface tape (second surface tape 62b) formed from a single member together with the interlayer tape 50 and wound outward in the winding axis direction of the second coil 12.

[0093] The manufacturing method of the transformer 100 of this embodiment includes a first coil winding step, an insulating tape winding step, and a second coil winding step, as in the first embodiment, and further includes a second insulating tape winding step of winding a second tape 90 and a third coil winding step of winding a third coil 13, which will be described later. Specifically, the transformer is manufactured as follows.

[0094] As with the transformer 100 of the first embodiment, after the first creepage tape 61 is wound, a first coil winding process is performed. After the first coil 11 is wound, an insulating tape winding process is performed in which the first tape 40 is wound. In this embodiment, as with the first embodiment, the interlayer tape 50 (interlayer tape portion 41) of the first tape 40 is wound first, and then the second creepage tape 62 is wound subsequently.

[0095] After the first tape 40 is wound, a second coil winding step is performed in which the second coil 12 is wound. In this embodiment, the second coil 12 is wound around the bobbin 30 in two layers. As in the transformer 100 of the first embodiment, the second coil 12 is wound around the base of the right terminal 336, and the first layer of the second coil 12 is further wound from right to left. The first layer of the second coil 12 is wound inside the second creeping tape 62 in the winding axis direction. After the first layer of the second coil 12 is wound, a partition tape 80 (partition tape 80a), which will be described later, is wound as a second insulating tape on top of the first layer of the second coil 12, as shown in FIG. 12(a). The partition tape 80 has a partition portion 81 (a wide portion of the second insulating tape) and a surface tape portion 83, as will be described later. As shown in FIG. 12(c), the second layer of the second coil 12 is wound from left to right (from top to bottom in the figure) inside the surface tape portion 83 in the winding axis direction. One end of the second coil 12 at the end of the winding is tied to the right terminal 337.

[0096] The partition tape 80 is an insulating tape that is wound between different layers of the coil 10 when the coil 10 is wound in multiple layers. The partition tape 80 is wound on top of a portion of the coil 10 (for example, the first layer of the second coil 12) and includes a partition section 81 that has a width equal to or greater than the length of the winding axis direction of the winding shaft section 31 of the bobbin 30. The partition section 81 is the portion of the partition tape 80 that is wound between different layers of the coil 10. The width of the partition section 81 refers to the longest length of the partition section 81 in the winding axis direction. The partition section 81 also includes a portion in which a cutout section 82, described below, is formed. The length of partition portion 81 in the longitudinal direction (circumferential direction of winding shaft portion 31) is preferably a length that allows one turn to be wound around the outer circumferential surface of coil 10 wound in the lower layer around partition portion 81. Specifically, the length of partition portion 81 in the longitudinal direction is equal to or greater than the outer circumferential length of coil 10 wound in the lower layer. As described above, the partition tape 80 in this embodiment has a surface-creeping tape portion 83 at one end of the partition portion 81. That is, as shown in FIG. 12(a), one end of the partition tape 80 in the longitudinal direction is hollow. The surface-creeping tape portion 83 is wound as the second surface-creeping tape 62c in the same layer as the second coil 12 in the second layer. Alternatively to this embodiment, the partition portion 81 and the second surface-creeping tape 62c may be separate members. In that case, the member including the partition portion 81 is the partition tape 80.

[0097] Similar to the peripheral tape 70 in the first embodiment, a notch 82 is provided at one end in the longitudinal direction of the partition 81. Similar to the notch 71 provided in the peripheral tape 70 in the first embodiment, the notch 82 may be formed by cutting out a corner of the partition 81 in a rectangular shape or by forming a concave edge of the partition 81. The notch 82 in this embodiment is a rectangular cutout portion of one outer side of the partition 81 in the width direction at one end in the longitudinal direction of the partition 81. The length of the notch 82 in the winding axis direction is equal to or greater than the sum of the width of the second surface tape 62c, which is integral with the partition tape 80, and the diameter of the second coil 12. The length of the notch 82 in the longitudinal direction is preferably equal to or greater than the diameter of the second coil 12.

[0098] The second coil 12 is disposed across the lower and upper layers of the partition tape 80 (partition portion 81) in the radial direction through the cutout portion 82. Specifically, as shown in Fig. 12(b), a partial length region (boundary portion 12g) of the second coil 12 connecting the first and second layers is disposed within the cutout portion 82 when viewed in the radial direction. The dimension in the tape length direction from one end of the partition portion 81 where the notch portion 82 is not provided to the notch portion 82 (indicated by a double-sided arrow in FIG. 12(a)) is preferably shorter than the length that allows one full turn of the coil 10 wound in the layer below the partition portion 81 on the outer circumferential surface. This makes it possible to provide a gap that allows the coil 10 (second coil 12) to cross over from the first layer to the second layer when the partition portion 81 is wound around the bobbin 30, as shown in FIG. 12(b). By providing this gap, the coil 10 can cross over between the lower and upper layers of the partition portion 81 through the notch portion 82.

[0099] As described above, notch 82 is provided on one outer side in the winding axis direction at one end of partition 81. Specifically, notch 82 is provided on the side (left side) where one end of coil 10 wound inside partition 81 is located. As shown in Figure 12(c), another part of the second coil 12 (such as the second coil 12 wound in the second layer) that is passed through the cutout 82 and placed in the upper layer of the partition tape 80 (partition 81) is wound from one side to the other side along the winding axis direction (from top to bottom on the paper). When the coil 10 is wound over a plurality of layers, the coil 10 of the upper layer can be stably wound on the coil 10 of the lower layer without being affected by rattle of the lower layer by winding a partition tape 80 between the lower and upper layers.

[0100] When the second coil 12 is wound, the second tape 90 (see FIG. 13(a)) is wound. Like the integrated insulating tape 40, the second tape 90 has an interlayer tape portion 91 (second interlayer tape 52) and a surface creepage tape portion 92 (third surface creepage tape 63). As shown in FIG. 13( a), part of the interlayer tape portion 91 of the second tape 90 is wound around the bobbin 30. When part of the interlayer tape portion 91 is wound around the bobbin 30, the third coil 13, one end of which is wound around the terminal 335, is pulled inward in the winding axis direction onto the interlayer tape portion 91. As shown in FIG. 13( b), the second tape 90 is wound so that the surface creeping tape portion 92 (the third creeping tape 63 on the lower side of the page) is positioned above the start portion (third start portion 13 a) of the third coil 13 that has been pulled inward in the winding axis direction. In other words, the third start portion 13 a is positioned between the second interlayer tape 52 and the third creeping tape 63. The interlayer tape portion 91 and the surface creeping tape portion 92 of the second tape 90 are wound continuously around the bobbin 30.

[0101] In this embodiment, the third coil 13 is wound around the bobbin 30 in two layers. As shown in Figure 13(c), the first layer of the third coil 13 is wound from right to left in the region inside the third creeping tape 63 in the winding axis direction. After the first layer of the third coil 13 is completely wound, the partition tape 80b is wound on top of the first layer of the third coil 13, as shown in Figures 14(a) and 14(b). The third coil 13 is pulled out to the upper side of the partition portion 81 through the cutout 82 provided in the partition portion 81 of the partition tape 80b, and a portion of the third coil 13 is disposed on top of the partition portion 81. The third coil 13 drawn out through the notch 82 is wound around the bobbin 30 from left to right (from top to bottom on the paper) as shown in Figure 14(c) . Specifically, the third coil 13 is wound around the inner region of the third creeping tape 63 in the winding axis direction. One end of the third coil 13 wound to the right side is wound around the terminal 338 .

[0102] After the third coil 13 is wound, as shown in Fig. 14(d), the outer tape 70 is wound at least once around the upper layer of the third coil 13. The outer tape 70 in this embodiment does not have the notch 71 in the first embodiment. In this embodiment, the creepage distance between the second lead-out portion 12a and the lead-out portion of the third coil 13 (third lead-out portion 13b) is also maintained at a specified value or more.

[0103] The present invention is not limited to the above-described embodiment, but includes various modifications and improvements as long as the object of the present invention is achieved.

[0104] In the above-described embodiment, first winding portion 11b and flange 32 are spaced apart by first creeping tape 61 or jig 200, but this is not limiting. For example, instead of the above-described embodiment, a sub-flange or protrusion may be provided midway along the length of winding shaft portion 31 in the winding axis direction. Specifically, the sub-flange or protrusion is provided inward of flange 32 in the winding axis direction by the distance desired to separate first winding portion 11b and flange 32. The sub-flange or protrusion may prevent first winding portion 11b from loosening further outward in the winding axis direction than the sub-flange, thereby maintaining the distance between flange 32 and first winding portion 11b. In this case, first creeping tape 61 need not be wound.

[0105] Furthermore, in this embodiment, both ends of the coil 10 are pulled out radially outward from the winding portion to the side end faces of the flange 32, but this is not limited to this. A groove recessed from the periphery of the flange 32 toward the axis may be provided in the flange 32, and both ends of the coil 10 may be pulled out through the groove to the outside of the flange 32 as viewed in the winding axis direction. The coil 10 pulled out through the groove may be wound around a separately provided winding terminal.

[0106] Like the notches (notch 71 and notch 82) in the second insulating tape, a notch may be provided at one end of the interlayer tape 50 or the second interlayer tape 52. Specifically, a notch may be provided at one end of the interlayer tape 50 by cutting out a corner in a rectangular shape. In this case, after the first coil 11 is wound around the winding shaft 31, the interlayer tape 50 is arranged on top of the first winding portion 11b before the first return portion 11f (see FIG. 4(a)) is arranged. Specifically, the interlayer tape 50 is arranged so that one end (terminal portion 11h (see FIG. 4(a))) of the first winding portion 11b is arranged within the notch in the interlayer tape 50 when viewed in the radial direction. When the interlayer tape 50 is arranged, the first coil 11 is bent at the terminal 333 at the terminal portion 11h. As a result, the first return portion 11f is arranged on the upper side of the interlayer tape 50. That is, the interlayer tape 50 is disposed between the first return portion 11f and the first winding portion 11b. The winding end of the first winding portion 11b is fixed by the interlayer tape 50 arranged in the upper layer, so that the first coil 11 can be easily bent at the end portion 11h.

[0107] In the above-described embodiment, the cutouts (cutouts 71 and 82) in the peripheral tape 70 and the partition tape 80 are provided at the lower end of both longitudinal ends of the wide portion or the partition portion 81, respectively. However, this is not limited to this. The cutouts may be provided at the upper end of both longitudinal ends of the wide portion or the partition portion 81. For example, the cutout 82 of the partition tape 80 shown in FIG. 12(a) may be provided on the side of the partition portion 81 on which the surface tape portion 83 is provided. In this case, the cutout 82 may be recessed in the longitudinal direction in the area on the inside of the surface tape portion 83 in the winding axis direction, on the side of the partition portion 81 along the winding axis direction.

[0108] In the above-described embodiment, a portion of the coil 10 (for example, the second start portion 12e in FIG. 1 or the third start portion 13a in FIG. 13(b)) is wound on the lower side of the surface creeping tape 60, which is wound in the same layer as the coil 10, but this is not limited to this. For example, the surface creeping tape 60 wound in the same layer may be wound radially outward (upper layer) from the second start portion 12e or the third start portion 13a. In this case, for example, when winding the integrated insulating tape 40, the entire interlayer tape portion 41 is wound around the winding shaft 31, and then the surface creeping tape portion 42 is wound around the winding shaft 31, and then the second start portion 12e is positioned on the upper side of the surface creeping tape portion 42. This allows the interlayer tape portion 41 and the surface creeping tape portion 42 to be wound continuously, thereby reducing the number of manufacturing steps.

[0109] The above embodiment encompasses the following technical ideas. (1) A transformer having a bobbin extending in a winding axis direction, a first coil wound on the inside of a plurality of coils wound in layers around the bobbin, a second coil wound on the outside of the first coil, an interlayer tape wound between the first coil and the second coil, and one or more surface tapes wound on the outside of the first coil or the second coil in the winding axis direction, wherein at least a portion of the surface tape and the interlayer tape form a single insulating tape. (2) The transformer according to (1), wherein the surface tape and the interlayer tape wound around the outside of the second coil in the winding axis direction are the insulating tape of a single component. (3) The transformer according to (2), wherein the surface tape and the interlayer tape wound around the outside of the first coil in the winding axis direction are separate members. (4) A transformer described in either (1) or (2), in which the surface tape and the interlayer tape wound around the outside of the first coil in the winding axis direction form the insulating tape of a single component. (5) A transformer according to any one of (1) to (4), further comprising a second insulating tape wound around the outside of a portion of the second coil and including a wide portion having a width equal to or greater than the length of the winding axis direction of the winding shaft portion of the bobbin, wherein a notch is provided at one end of the wide portion in the longitudinal direction, and the second coil is disposed across the inside and outside of the second insulating tape through the notch. (6) The transformer described in (5), wherein the notch is provided on one side of the outer side in the winding axis direction at the one end of the wide portion, and another part of the second coil that is passed through the notch and positioned outside the second insulating tape is wound along the winding axis direction from the one side to the other side opposite the one side. (7) A transformer according to any one of (1) to (6), wherein a portion of the second coil is disposed between the interlayer tape and the surface tape formed of a single member with the interlayer tape and wound around the outside of the second coil in the winding axis direction. (8) The transformer according to any one of (1) to (7), wherein both ends of the first coil are drawn out to one side in the winding axis direction, both ends of the second coil are drawn out to the other side in the winding axis direction, and the surface tape is wound around at least the other side of the first coil and at least the one side of the second coil. (9) A transformer as described in (8), in which the surface tape wound around the other side of the first coil, the surface tape wound around the one side of the second coil, and the interlayer tape are a single insulating tape. (10) The transformer according to any one of (1) to (7), wherein both ends of the first coil and the second coil are pulled out to one side in the winding axis direction, and the surface tape is wound around the one side of the first coil and the second coil and the other side of the first coil or the second coil in the winding axis direction. (11) A transformer as described in (10), in which the total length in the winding axis direction of the surface tape arranged on the other side of the first coil or the second coil is equal to the respective lengths of the surface tape arranged on the one side of the first coil and the second coil. (12) A bobbin set including a bobbin extending in a winding axis direction and an insulating tape having a width equal to or greater than the length of a winding shaft portion in the winding axis direction, sandwiched between a pair of flange portions spaced apart from each other in the winding axis direction of the bobbin, wherein the insulating tape has a surface tape portion at one end of the insulating tape in the width direction, on the outside, having a length equal to or greater than the circumferential length of the winding shaft portion. (13) A method for manufacturing a transformer having a bobbin extending in a winding axis direction, a first coil wound on the inner side of multiple coils wound in layers around the bobbin, a second coil wound around the first coil, and an insulating tape wound around the bobbin, wherein the insulating tape has an interlayer tape portion wound between the first coil and the second coil and a creeping tape portion wound around the outer side of the first coil or the second coil in the winding axis direction, the interlayer tape portion and the creeping tape portion being formed as a single insulating tape, the method including: a first coil winding step of winding the first coil around the winding shaft portion; an insulating tape winding step of winding a portion of the interlayer tape portion and the creeping tape portion continuously around the bobbin; and a second coil winding step of winding the second coil around the outer side of the interlayer tape portion. (14) The transformer according to any one of (1) to (10), wherein the interlayer tape and the surface tape are configured by laminating a base layer and an adhesive layer. (15) A transformer described in any one of (1) to (10), wherein the width of the interlayer tape is equal to or greater than the length of the winding shaft portion in the winding axis direction, and the length of the interlayer tape in the longitudinal direction is equal to or greater than the length of the outer peripheral surface of the first coil wound inside the interlayer tape in the radial direction of the bobbin. (16) A transformer described in any one of (1) to (10), wherein the surface tape is arranged on the inside of both side edges of the interlayer tape extending in the length direction of the interlayer tape in the winding axis direction. (17) The transformer according to any one of (5) to (10), wherein the cutout portion is formed by cutting out a rectangular or square shape on one side in the winding axis direction at one end of the wide portion in the longitudinal direction. (18) The transformer according to any one of (1) to (10), wherein the first coil or the second coil is wound in layers across a plurality of layers, a partition tape is wound between a lower layer portion wound on the inside of the plurality of layers and an upper layer portion wound outside the lower layer portion, and the partition tape has a partition portion disposed between the lower layer portion and the upper layer portion and a surface tape portion wound outside the winding axis direction of the upper layer portion. (19) The transformer described in (9), wherein the insulating tape has a rectangular interlayer tape portion, and the surface tape portion is provided at a diagonal position of the rectangular interlayer tape portion, extending in the longitudinal direction of the interlayer tape portion. (20) The transformer according to (11), wherein the width of the surface tape wound around the other side of one of the first coil and the second coil, which has a longer winding width to be wound around the winding shaft portion, is smaller than the width of the surface tape wound around the other side of the other coil, which has a shorter winding width to be wound around the winding shaft portion. (21) The method for manufacturing a transformer according to (13), wherein in the insulating tape winding step, the surface tape portion is wound after the interlayer tape portion is wound.

Claims

1. a bobbin extending in the winding axis direction; a first coil wound on the inner side of the plurality of coils wound in layers around the bobbin; a second coil wound around the outside of the first coil; an interlayer tape wound between the first coil and the second coil; one or more creepage tapes wound around the outside of the first coil or the second coil in the winding axis direction, At least a part of the surface tape and the interlayer tape are a single insulating tape, a second insulating tape wound around the outside of a portion of the second coil and including a wide portion having a width equal to or greater than the length of the winding axis direction of the winding shaft portion of the bobbin; a notch is provided at one end of the wide portion in the longitudinal direction, a transformer, wherein the second coil is disposed across the inside and outside of the second insulating tape through the cutout portion.

2. the notch is provided on one outer side in the winding axis direction at the one end of the wide portion, 2. The transformer according to claim 1, wherein another part of the second coil, which is passed through the notch and arranged outside the second insulating tape, is wound along the winding axis direction from the one side to the other side opposite to the one side.

3. A bobbin extending in the direction of the winding axis; a first coil wound on the inner side of the plurality of coils wound in layers around the bobbin; a second coil wound around the outside of the first coil; an interlayer tape wound between the first coil and the second coil; one or more creepage tapes wound around the outside of the first coil or the second coil in the winding axis direction, At least a part of the surface tape and the interlayer tape are a single insulating tape, a part of the second coil is disposed between the interlayer tape and the creeping tape, which is formed as a single member with the interlayer tape and wound around the outside of the second coil in the winding axis direction.

4. A bobbin extending in the direction of the winding axis; a first coil wound on the inner side of the plurality of coils wound in layers around the bobbin; a second coil wound around the outside of the first coil; an interlayer tape wound between the first coil and the second coil; one or more creepage tapes wound around the outside of the first coil or the second coil in the winding axis direction, At least a part of the surface tape and the interlayer tape are a single insulating tape, both ends of the first coil are drawn out to one side in the winding axis direction, both ends of the second coil are drawn out to the other side in the winding axis direction, the surface-creeping tape is wound around at least the other side of the first coil and at least the one side of the second coil, a transformer in which the surface tape wound around the other side of the first coil, the surface tape wound around the one side of the second coil, and the interlayer tape are a single insulating tape.

5. 5. The transformer according to claim 1, wherein the surface tape and the interlayer tape wound around the outside of the second coil in the winding axis direction form the insulating tape of a single member.

6. The transformer according to claim 5 , wherein the surface tape wound around the outside of the first coil in the winding axis direction and the interlayer tape are separate members.

7. the surface tape and the interlayer tape wound around the outside of the second coil in the winding axis direction form the insulating tape of one member, 5. The transformer according to claim 1, wherein the surface tape and the interlayer tape wound around the outside of the first coil in the winding axis direction form the insulating tape of a single member.

8. both ends of the first coil and the second coil are drawn out to one side in the winding axis direction, 5. The transformer according to claim 1, wherein the surface tape is wound around the one side of the first coil and the second coil and the other side of the first coil or the second coil in the winding axis direction.

9. The total length of the surface tape arranged on the other side of the first coil or the second coil in the winding axis direction is the length is equal to the length of each of the surface tapes arranged on the one side of the first coil and the second coil, 9. The transformer according to claim 8, wherein a width of the surface tape wound around the other side of one of the first coil and the second coil, which has a larger winding width, is shorter than a width of the surface tape wound around the other side of the other of the first coil and the second coil, which has a smaller winding width.

10. a bobbin extending in the winding axis direction; a first coil wound on the inner side of the plurality of coils wound in layers around the bobbin; a second coil wound around the outside of the first coil; an insulating tape wound around the bobbin; a second insulating tape wound around the outside of a portion of the second coil and including a wide portion having a width equal to or greater than a length of the winding axis direction of the winding shaft portion of the bobbin, The insulating tape is an interlayer tape portion wound between the first coil and the second coil; a surface creeping tape portion wound around the outside of the first coil or the second coil in the winding axis direction, the interlayer tape portion and the surface tape portion are formed as a single insulating tape, a notch is provided at one end of the wide portion of the second insulating tape in the longitudinal direction, and the second coil is disposed across the inside and outside of the second insulating tape through the notch; a first coil winding step of winding the first coil around the bobbin; an insulating tape winding step in which a portion of the interlayer tape portion and the surface tape portion are continuously wound around the bobbin; a second coil winding step of winding the second coil around the outside of the interlayer tape portion; Including, After the second coil winding step, the second insulating tape is disposed on the outside of the second coil; A method for manufacturing a transformer, wherein one end of the winding end of the second coil is pulled out from the inside to the outside of the second insulating tape through the cutout portion.

11. a bobbin extending in the winding axis direction; a first coil wound on the inner side of the plurality of coils wound in layers around the bobbin; a second coil wound around the outside of the first coil; and an insulating tape wound around the bobbin, The insulating tape is an interlayer tape portion wound between the first coil and the second coil; a surface creeping tape portion wound around the outside of the first coil or the second coil in the winding axis direction, the interlayer tape portion and the surface tape portion are formed as a single insulating tape, a first coil winding step of winding the first coil around the bobbin; an insulating tape winding step in which a portion of the interlayer tape portion and the surface tape portion are continuously wound around the bobbin; a second coil winding step of winding the second coil around the outside of the interlayer tape portion; Including, In the insulating tape winding step, The interlayer tape portion is wound, a portion of the second coil is disposed outside the interlayer tape portion; the surface-creeping tape portion is wound around the outside of the portion of the second coil, In the second coil winding step, the second coil is wound inside the surface tape portion in the winding axis direction, the portion of the second coil is disposed between the interlayer tape and the surface tape, which is formed as a single member with the interlayer tape and wound around the outside of the second coil in the winding axis direction.

12. a bobbin extending in the winding axis direction; a first coil wound on the inner side of the plurality of coils wound in layers around the bobbin; a second coil wound around the outside of the first coil; and an insulating tape wound around the bobbin, The insulating tape is an interlayer tape portion wound between the first coil and the second coil; a first surface tape portion wound around the outside of the first coil in the winding axis direction; a second creeping tape portion wound around the outside of the second coil in the winding axis direction, the interlayer tape portion, the first creeping tape portion, and the second creeping tape portion are formed as a single insulating tape, a first coil winding step of winding the first coil around the bobbin; an insulating tape winding step in which the first surface tape portion, a portion of the interlayer tape portion, and the second surface tape portion are continuously wound around the bobbin; a second coil winding step of winding the second coil around the outside of the interlayer tape portion; Including, In the first coil winding step, the first coil is pulled in from one side of the winding axis direction toward a winding shaft portion of the bobbin, wound around the winding shaft portion, and pulled out from the winding shaft portion to the one side, In the insulating tape winding step, the first surface tape portion is wound around at least the other side of the first coil in the winding axis direction, the second creeping tape portion is wound around at least one side of the second coil in the winding axis direction.

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