JPH0737733A - Transformer - Google Patents

Abstract

PURPOSE:To obtain a thin type multilayered coil wherein characteristics are excellent in a high frequency region, connection of a plurality of coil conductors formed on a sheet is facilitated, and connection reliability of the coil conductors is high. CONSTITUTION:A transformer 10 contains a first multilayered coil 12 and a second multilayered coil stacked on the coil 12. A core 34 is fixed to the multilayered coils. The multilayered coil contains a sheet constituted of insulating material, and a plurality of coil conductors parallel with each other are formed on the sheet. The coil conductors are coated with insulating material. The sheet is tent and formed in a spiral type. Leading-out parts are formed at end portions of the coil conductors. By stacking and connecting the leading- out parts of the coil conductors, a plurality of the coil conductors are connected in series. Winding is formed between leading-out parts 22b of the first multilayered coil 12. Winding is formed between leading-out parts 28a and 30b of the other multilayered coil.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a transformer, and more particularly to a thin transformer used for various switching power supplies.

[0002]

2. Description of the Related Art FIG. 8 is a sectional view showing an example of a conventional transformer. The transformer 1 includes a bobbin 2. A primary winding 3 and a secondary winding 4 are wound around the bobbin 2. As the windings 3 and 4, for example, wire conductors whose circumference is covered with an insulator are used. Further, in order to reduce the thickness of the transformer, there is a transformer using a coil in which insulating sheets having coil conductors are laminated and coil conductors are connected between a plurality of insulating sheets via through holes.

Further, as shown in FIG. 9, one turn of the insulating sheet 5 on which the coil conductor 6 of one turn is formed is laminated, and the ends of the coil conductor 6 are connected on the outer peripheral side of the insulating sheet 5. There was a transformer 1 that used a coil. In such a transformer 1, the transformer 1 is configured by forming coils having different numbers of turns and stacking them.
When such a coil is used, it is not necessary to internally connect the coil conductor by a through hole or the like, which simplifies manufacturing. Further, as shown in FIG. 10, one sheet of insulating sheet 5 on which a plurality of turns of coil conductor 6 is formed is laminated, and the ends of the coil conductor 6 are connected to the inner peripheral side and the outer peripheral side of the insulating sheet 5. There was a transformer 1 that used a coil. In this transformer 1, since the coil conductors 6 having a plurality of turns are formed on one insulating sheet 5, the number of insulating sheets 5 can be reduced.

[0004]

However, in the transformer in which the primary winding and the secondary winding are formed on the bobbin, when used in a high frequency region, the current distribution is biased due to the skin effect, and the substantial resistance of the conductor is reduced. growing. Further, in a transformer using a coil in which insulating sheets each having a one-turn coil conductor are laminated, the number of laminated insulating sheets increases as the number of turns increases, and a thin transformer cannot be obtained.

Further, in a transformer using a coil in which insulating sheets having a plurality of turns of coil conductors are laminated,
The lead-out portion of the coil conductor must be connected on both the inner peripheral side and the outer peripheral side. Therefore, the thickness of the coil part may increase due to the deformation of the connection part and the thickness of the solder,
There were problems such as insufficient connection and low reliability.

Therefore, a main object of the present invention is that the characteristics are good even when used in a high frequency region, and a plurality of coil conductors formed on a sheet can be easily connected,
Moreover, it is an object of the present invention to provide a thin laminated coil having a highly reliable connection of coil conductors.

[0007]

SUMMARY OF THE INVENTION The present invention is a transformer in which a plurality of laminated coils, each of which is formed by bending a sheet on which a coil conductor is formed and laminated, is laminated. The laminated coil is made of an insulating material. A sheet, a plurality of thin-film coil conductors formed so as to be parallel to each other on the sheet, and an insulating coating material formed on the coil conductor, the sheet is bent to make a plurality of coil conductors spiral, This is a transformer in which a plurality of coil conductors are connected in series to form a winding by connecting a lead-out portion where a coil conductor is drawn out.

[0008]

By folding the sheet, a plurality of spiral coil conductors are formed. Furthermore, by connecting the lead-out portions of the coil conductors and connecting the coil conductors in series, it is possible to obtain a winding having a large number of turns. Since the coil conductors are connected at the ends of the drawn coil conductors, spot welding, soldering, caulking or the like can be used. Further, since the coil conductor has a thin film shape, the current distribution can be made substantially uniform even when used in a high frequency region.

[0009]

According to the present invention, since the coil conductors are connected at the lead-out portion, it is not necessary to connect the coil conductors inside the sheet. Therefore, it is not necessary to form a through hole or the like, and the work of connecting the coil conductors can be easily performed. Moreover, since the coil conductors can be connected by a method such as spot welding, soldering, or caulking, the connection reliability can be improved as compared with the case where the coil conductors are connected through a through hole or the like. In addition, since there is no coil conductor connection inside the seat, there is no need for a space for connection,
The coil length can be shortened or the coil width can be expanded, and copper loss can be reduced. Moreover, since the coil conductor has a thin film shape, the effect of the skin effect is small and the current distribution is substantially uniform. Therefore, even when the coil conductor is used in a high frequency range, the substantial resistance of the coil conductor is not significantly reduced, and the characteristics are not significantly deteriorated.

Further, since a plurality of coil conductors are formed on the sheet and the windings are formed by connecting them, the number of windings can be increased with a small number of laminations, and a thin transformer can be obtained. Obtainable. Furthermore, since the coil conductors are connected to each other at the lead-out portion that is pulled out to the outer peripheral side, the coil does not become thick due to deformation of the connection portion or soldering, and a thin transformer can be obtained.

The above-mentioned objects, other objects, features and advantages of the present invention will become more apparent from the following detailed description of the embodiments with reference to the drawings.

[0012]

1 is a plan view showing an embodiment of the present invention, FIG. 2 is a front view thereof, and FIG. 3 is a rear view thereof. The transformer 10 includes a first laminated coil 12 and a second laminated coil 14. First laminated coil 12
Includes a sheet 16, as shown in FIG. Sheet 16
Is formed of an insulating material such as a polyimide substrate. In this embodiment, the sheet 16 is formed in a meandering shape.

A plurality of coil conductors 18, 20, 22 are formed on one surface of the sheet 16. These coil conductors 18, 20, 22 are formed in the longitudinal direction of the sheet 16 so as to be parallel to each other. Coil conductor 18, 2
0 and 22 are formed by a method such as etching or printing. Both ends of the coil conductor 18 are pulled out from the sheet 16, and thereby lead-out portions 18a and 18b are formed. Similarly, at both ends of the coil conductors 20 and 22,
Drawers 20a and 20b and drawer 22 respectively
a and 22b are formed.

Further, an insulating coating material 24 is formed so as to cover the coil conductors 18, 20, 22. The sheet 16 and the insulating coating material 24 have a thickness of, for example, 2
0 μm polyimide substrate is used, coil conductor 18,
For example, copper foil having a thickness of 70 μm is used as 20, 22.

The sheet 16 is obliquely bent at the portions indicated by the dotted lines A, B and C. Thereby, as shown in FIG. 5, the sheet 16 is formed in a spiral shape. Correspondingly, the coil conductors 18, 20, 22 also have a spiral shape, and windings each having three turns are formed. Then, the drawer portions 18a, 20a, 22a and the drawer portion 18b,
20b and 22b project outside the formed winding.
The drawer portion 18b and the drawer portion 20a are overlapped with each other, and the drawer portion 20b and the drawer portion 22a are overlapped with each other. The drawer portions 18b and 20a are connected, and the drawer portions 20b and 22a are connected. Connection of the drawn-out portion can be performed by a method such as spot welding, soldering, or caulking.

By connecting these lead-out portions, the three windings formed by the coil conductors 18, 20, 22 are connected in series. Therefore, a winding of 9 turns is formed between the drawing portion 18a and the drawing portion 22b.

The second laminated coil 14 is formed in the same manner. As shown in FIG. 6, the second laminated coil 14 also includes a sheet 26 formed of an insulating material to meander. In this embodiment, two coil conductors 28 and 30 are formed on the sheet 26. Coil conductor 2
8 is formed up to the middle of the sheet 26, and the coil conductor 28
Lead-out portions 28a and 28b are formed at both ends of the. Further, the coil conductor 30 is formed from one end to the other end of the sheet 26, and the lead-out portions 30 a, 3 are provided at both ends of the coil conductor 30.
0b is formed. Further, the insulating coating material 32 is formed so as to cover the coil conductors 28 and 30.

The sheet 26 is obliquely bent at the portions indicated by the dotted lines D, E, F and G. As a result, the sheet 26 has a spiral shape, and the coil conductors 28, 30
Also becomes spiral. Since the coil conductor 28 is formed up to the intermediate portion of the sheet 26, the coil conductor 28 is a two-turn winding. Further, since the coil conductor 30 is formed from one end to the other end of the sheet 26, the coil conductor 30 becomes a winding of three turns. Then, the lead-out portion 28b of the coil conductor 28 and the lead-out portion 30a of the coil conductor 30 are overlapped with each other, and the lead-out portion 28b and the lead-out portion 30a are connected. As a result, a winding of 5 turns is formed between the lead portion 28a and the lead portion 30b.

The first laminated coil 12 and the second laminated coil 14 are superposed on each other. At this time, the lead-out portion of the laminated coil 12 and the lead-out portion of the laminated coil 14 are superposed so as to be arranged on opposite sides. Then, the E-shaped cores 34 and 36 are butted against each other from both sides of the laminated coils 12 and 14. At this time, the central leg portions of the cores 34, 36 are
The space portions formed in the center of 2, 14 are butted against each other.
In addition, the legs on both sides of the cores 34 and 36 have the laminated coil 1
The side surfaces where the drawn-out portions 2 and 14 are not formed are butted. The bent portions 38 of the laminated coils 12 and 14 are arranged outside the cores 34 and 36.

In this transformer 10, a winding of 9 turns is formed between the lead-out portions 18a and 22b of the first laminated coil 12, and the lead-out portions 28a and 28a of the second laminated coil 14 are formed.
A winding of 5 turns is formed between 30b. Therefore, the first laminated coil 12 and the second laminated coil 14 form the transformer 10.

In this transformer 10, the coil conductors 18,
Since the connection of 20, 22 and the connection of the coil conductors 28, 30 are made at the lead-out portion, it is not necessary to form a through hole inside. Therefore, the work of connecting the coil conductors can be easily performed. Further, since the drawn-out portion can be connected by spot welding, soldering, caulking, etc., the connection reliability can be improved as compared with the connection by the through hole. Furthermore, since the coil conductors having a plurality of turns are connected, the number of lead portions can be reduced. Further, since the coil conductors are connected to each other at the lead-out portion drawn to the outer peripheral side, the manufacturing is simpler than that of the coil connected to the inner peripheral side.

Further, unlike the case of soldering at the sheet end, the laminated coil does not become thick due to the deformation of the connecting portion and the thickness of the solder. Further, since the coil conductor can be formed into a spiral shape having a plurality of turns by bending the sheet on which the plurality of coil conductors are formed, it is possible to reduce the number of layers to be laminated even in a laminated coil having a large number of turns. Moreover,
Since the bent portion of the laminated coil is arranged outside the core, the thickness of the bent portion does not affect the thickness of the entire transformer. From these things, a thin transformer can be obtained.

Furthermore, since there is no internal connection, no extra space is required for connection, the coil length can be shortened or the coil width can be expanded, and copper loss can be reduced. Further, since the coil conductor is formed in a thin film shape, the skin effect is less affected even when used in a high frequency region, and the current distribution becomes substantially uniform. Therefore, even if this transformer is used as a switching power supply or the like, good characteristics can be obtained.

In this transformer, since the coil conductor formed on the sheet is covered with the insulating coating material,
The coil conductor does not short even when the sheet is bent. Also,
The number of times of meandering and bending of the sheet can be changed depending on the number of turns of the winding formed by the coil conductor, and of course a sheet which does not meander can be used.

[Brief description of drawings]

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

FIG. 2 is a front view of the transformer shown in FIG.

FIG. 3 is a rear view of the transformer shown in FIG.

FIG. 4 is a plan view showing a sheet and a coil conductor of a first laminated coil used in the transformer shown in FIG.

5 is a perspective view showing a first laminated coil using the sheet shown in FIG.

6 is a plan view showing a sheet and a coil conductor of a second laminated coil used in the transformer shown in FIG.

7 is a perspective view showing a second laminated coil using the sheet shown in FIG.

FIG. 8 is a schematic cross-sectional view showing an example of a conventional transformer as the background of the present invention.

FIG. 9 is an exploded perspective view showing another example of a conventional transformer.

FIG. 10 is an exploded perspective view showing still another example of the conventional transformer.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Transformer 12 1st laminated coil 14 2nd laminated coil 16 Sheet 18 Coil conductor 20 Coil conductor 22 Coil conductor 18a, 18b Lead-out part 20a, 20b Lead-out part 22a, 22b Lead-out part 24 Insulation coating 26 Sheet 28 coil Conductor 30 Coil conductor 28a, 28b Lead-out portion 30a, 30b Lead-out portion 32 Insulation coating material

Claims (1)

[Claims] 1. A transformer in which a plurality of laminated coils, each of which is formed by bending and laminating a sheet on which a coil conductor is formed, is laminated, the laminated coil including: the sheet formed of an insulating material; A plurality of thin-film coil conductors formed so as to be parallel to each other, and an insulating coating material formed on the coil conductors, wherein the sheet is bent to make the plurality of coil conductors spiral, A transformer in which a plurality of the coil conductors are connected in series to form a winding by connecting the drawn-out portion.