JPH09162035A - Coil device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a coil device using a laminated sheet coil and having both a small quantity of energy loss and high efficiency. SOLUTION: In a core 2 mounted on a laminated sheet coil 20, a gap G for adjusting the inductance of a coil device is provided. The closer one of the constituent sheet coils 23, 24 of the laminated sheet coil 20 is conventionally to the position of the gap G, the more separated its disposal is formed from the gap G. As a result, the magnetic fields leaking from the gap G and passing through ths sheet coils 23, 24 are all made small to reduce the energy loss of the coil device.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a coil device using a laminated sheet coil, which is used as a transformer or an inductor.

[0002]

2. Description of the Related Art An electronic circuit generally used in electronic equipment is composed of various electronic components mounted on an insulating substrate. When a transformer is required as an electronic circuit, a separately formed transformer is placed on the insulating substrate. However, in this case, since the transformer itself is large, there is a problem that the mounting space becomes large.

Therefore, recently, various coil devices using a laminated sheet coil in which a plurality of sheet coils are laminated are developed. An example of a coil device used as a transformer will be described with reference to FIGS. 2 to 4.

The coil device comprises a laminated sheet coil 1 and a core 2.

The laminated sheet coil 1 is composed of two primary coil substrates 3 and one secondary coil substrate 4.

The primary coil substrate 3 is a disk-shaped insulating substrate 5
And a sheet coil 6 serving as a primary coil provided so as to face the front and back surfaces of the insulating substrate 5. See
The coil 6 is formed in a spiral shape from the outer peripheral side toward the center side. The sheet coil 6 is formed of a conductive thin film such as copper foil. The ends on the center side of the sheet coil 6 on the front and back sides are through-holes provided on the insulating substrate 5.
They are electrically connected to each other via a hole 7. The ends on the outer peripheral side of the front and back sheet coils 6 are connected to the input / output terminals T1 and T2.
2, T3 and T4, respectively. A through hole 8 having a circular opening shape is provided in the center of the insulating substrate 5.

The secondary coil substrate 4 is a disk-shaped insulating substrate 9
And a sheet coil 10 serving as a secondary coil provided so as to face the front and back surfaces of the insulating substrate 9. The sheet coil 10 is formed in a spiral shape from the outer peripheral side toward the center side. The sheet coil 10 is formed of a conductive thin film such as copper foil. Front and back seams
The ends of the coil 10 on the center side are electrically connected to each other via a through-hole 11 provided on the insulating substrate 9. The ends on the outer peripheral side of the sheet coil 10 formed on the front and back surfaces are connected to the input / output terminals T5 and T6, respectively. In addition, in the central portion of the insulating substrate 9, the through-hole 1 having a circular opening shape
2 are provided. The outer diameter of the secondary coil substrate 9 and the inner diameter of the through hole 12 are set to be the same as the outer diameter of the primary coil substrate 5 and the inner diameter of the through hole 8.

The number of turns of the sheet coil 6 and the sheet coil 10 is determined according to the characteristics of the transformer. The pattern width of the sheet coils 6 and 10 is determined in consideration of the resistance value and the number of turns of each of the sheet coils 6 and 10, and generally the pattern is increased as the number of turns increases. Width becomes narrower.

The laminated sheet coil 1 is formed by laminating the primary coil substrate 3, the secondary coil substrate 4, and the primary coil substrate 3 in this order from the bottom. A prepreg 13 is sandwiched between the primary coil substrate 3 and the secondary coil substrate 4 for the purpose of adhering and insulating the two, and they are integrally formed by vacuum pressure molding means. Also, the laminated sheet coil 1
An insulating layer 14 is formed on the front and back surfaces of the. Through holes 8 and 12 provided in the primary coil substrate 3 and the secondary coil substrate 4
Core mounting holes 1 for mounting cores 2 by overlapping
5 are formed. Input / output terminals T2 and T3 are lead wires 16
Connected via As a result, the sheet coils 6 of the two primary coil substrates 3 are connected in series, and the number of turns of the primary coil increases.

The core 2 is composed of a pair of an upper core portion 2A and a lower core portion 2B made of, for example, ferrite. 2 A of upper core parts are comprised from the bottomed cylindrical part 17 and the column-shaped protrusion part 18 standingly provided by the center part of the inner bottom face of the bottomed cylindrical part 17. The inner diameter of the bottomed cylindrical portion 17 is set to be slightly larger than the outer diameter of the primary coil substrate 3. The lower core portion 2B is also configured in the same manner as the upper core portion 2A, except that a cutout portion 19 is provided on the side surface of the bottomed cylindrical portion 17. From this cutout portion 19, the input / output terminal T1
Lead wires (not shown) connected to T4, T5, and T6 are drawn out of the core 2. In addition, the protrusion 1
The height of 8 is a predetermined dimension between the end surfaces of the projecting portions 17 of the upper core portion 2A and the lower core portion 2B when the end surfaces of the bottomed cylindrical portions 17 of the upper core portion 2A and the lower core portion 2B collide with each other. It is set so that the gap G is formed. The gap G is provided to prevent the magnetic flux density passing through the core 2 from being saturated early, and the inductances of the coil sheets 6 and 10 are adjusted. The gap G is provided at the center of the laminated sheet coil 1 in order to reduce the leakage magnetic field to the outside. The core 2 is inserted by inserting the protrusions 18 of the upper core portion 2A and the lower core portion 2B into the core mounting hole 15 formed in the central portion of the laminated sheet coil 1.
Is attached.

In general, when a high-frequency current is passed through a conductor, a skin effect is produced in which the current is biased toward the surface area of the conductor. Therefore, the resistance value of the conductor becomes large, and energy loss occurs. However, in the coil device,
By designing the thicknesses of the sheet coils 6 and 10 in advance, the influence of the skin effect can be reduced. Further, since the sheet coils 6 and 10 can be formed on the front and back surfaces of the insulating substrates 5 and 9 with high positional accuracy, variations in characteristic values in the coil device can be reduced, and the coupling degree between the primary coil and the secondary coil can be reduced. It has the feature that

[0012]

However, there has been a problem that an eddy current is generated in the sheet coil due to the leakage magnetic field generated from the gap of the core mounted on the laminated sheet coil. From Faraday's law of electromagnetic induction, the magnetic flux that generates an eddy current is proportional to the time change of the magnetic flux density. Therefore, a large eddy current is generated in the place where the magnetic flux density is large, that is, in the sheet coil near the gap. For this reason, the sheet placed near the gap
The energy loss in the coil has increased, and the efficiency of the coil device has decreased. On the other hand, the magnetic flux density of the leakage magnetic field gradually decreases with increasing distance from the gap.
The eddy current generated in the sheet coil is reduced, and the energy loss is reduced.

Therefore, the present invention aims to provide a coil device for solving the above problems.

[0014]

The coil device of the present invention comprises:
In order to solve the above-mentioned object, it is configured as follows. That is, it is provided with a laminated sheet coil in which a plurality of sheet coils are laminated, a core mounting hole provided in the laminated sheet coil, and a core mounted with a gap inside the core mounting hole. In the coil device, the sheet coil is formed farther from the gap as it is closer to the position of the gap.

In the vicinity of the gap provided in the core, the magnetic flux density of the leakage magnetic field is large. For this reason, the sheet coil located closer to the gap is formed farther from the center of the core mounting hole in the radial direction. As a result, the magnetic flux of the leakage magnetic field passing through the sheet coil is reduced and the eddy current is reduced.
Further, since the sheet coil can be formed adjacent to the core mounting hole as the distance from the gap increases, the area where the sheet coil can be formed becomes wider. Therefore, the pattern width of the sheet coil can be increased. Therefore, the resistance value of the whole sheet coil connected in series becomes small.

[0016]

BEST MODE FOR CARRYING OUT THE INVENTION An embodiment of a coil device according to the present invention will be described with reference to FIG. The coil device is composed of the laminated sheet coil 20 and the core 2. The sheet coil 23 is the same as the conventional example except the sheet coils 23 and 24 formed on the front and back surfaces of the two primary coil substrates 21 and the one secondary coil substrate 22 constituting the laminated sheet coil 20. And 24 will be mainly described, and the description of other parts will be simplified. The description of the core 2 will be omitted, and the same components as those of the conventional example will be described using the same numbers.

The primary coil substrate 21 is composed of a disk-shaped insulating substrate 5 and a sheet coil 23 which is provided as a primary coil so as to face the front and back surfaces of the insulating substrate 5.
The sheet coil 23 is formed in a spiral shape from the outer peripheral side toward the center side. The sheet coil 23A formed on the surface has a uniform pattern width. The sheet coil 23B formed on the back surface is the sheet coil 23A.
3 is a shape obtained by removing the portion within the area of the distance W1 in the radial direction from the central axis L of the core mounting hole 15.
Therefore, the sheet coil 23 adjacent to the core mounting hole 15
The pattern width of B is gradually narrowed toward the end on the center side. The sheet coil 23 is formed of a conductive thin film such as copper foil, and the sheet coils 23A and 23B on the front and back surfaces are formed.
The end portion on the center side of the through-hole is provided on the insulating substrate 5.
And are electrically connected to each other via the module 7. Front and back seams
The outer peripheral ends of the coils 23A and 23B are connected to the input / output terminals T1 and T2, and T3 and T4, respectively. Further, a through hole 8 having a circular opening shape is provided in the central portion of the insulating substrate 5.

The secondary coil substrate 22 is composed of a disk-shaped insulating substrate 9 and a sheet coil 24 which is a secondary coil provided so as to face the front and back surfaces of the insulating substrate 9.
The sheet coil 24 is formed in a spiral shape from the outer peripheral side toward the center side. The sheet coil 24 is formed in a region distant from the central axis L of the core mounting hole 15 by a distance W2 in the radial direction. The distance W2 is set longer than the distance W1. The sheet coil 24 is formed of a conductive thin film such as copper foil, and the ends of the sheet coil 24 on the center side of the front and back surfaces are the through holes 1 provided on the insulating substrate 9.
1 and are electrically connected to each other. The outer peripheral side ends of the sheet coils 24 on the front and back sides are respectively connected to the input / output terminal T5.
And T6. The outer diameter of the secondary coil substrate 22 and the inner diameter of the through hole 12 are set to be the same as the outer diameter of the primary coil substrate 21 and the inner diameter of the through hole 8. The number of turns of the sheet coil 24 is determined from the relationship with the number of turns of the sheet coil 23.

The laminated sheet coil 20 includes a primary coil substrate 21, a secondary coil substrate 22, and a primary coil substrate 21 from the bottom.
It is formed by laminating in order. When laminating, the sheet coil 23B of the primary coil substrate 21 is placed inside the laminated sheet coil 20. The through holes 8 and 12 provided in the primary coil board 21 and the secondary coil board 22 are overlapped with each other to form a core mounting hole 15 for mounting the core 2.

The core 2 is mounted on the laminated sheet coil 20 by inserting the protrusions 18 of the upper core portion 2A and the lower core portion 2B into the core mounting holes 15. At this time, the gap G provided in the core 2 is equal to the core mounting hole 15
Is formed in the central part of the. Therefore, most of the magnetic flux leaking from the gap G passes through the portion adjacent to the gap G, that is, the sheet coil 24 of the secondary coil substrate 22.
It is. However, since the sheet coil 24 is formed at a distance W2 from the central axis L of the core mounting hole 15 in the radial direction, the magnetic flux density of the leakage magnetic field passing through the sheet coil 24 decreases. As a result, the eddy current generated in the sheet coil 24 becomes small.

Next, the magnetic flux density of the leakage magnetic field from the gap G is large in the region slightly away from the gap G, that is, in the sheet coil 23B of the primary coil substrate 21. However, the sheet coil 23B is formed at a distance W1 from the central axis L of the core mounting hole 15 in the radial direction.
Therefore, the influence of the leakage magnetic field on the sheet coil 23B is reduced here as well.

As the distance from the gap G increases, the influence of the leakage magnetic field decreases. That is, the primary coil substrate 21
The influence of the leakage magnetic field on the sheet coil 23A formed on the surface of the is reduced. Therefore, as the distance from the gap G increases, the sheet coil can be formed adjacent to the core mounting hole 15. In other words, the farther from the gap G, the wider the area where the sheet coil can be formed. Therefore, the sheet coils 24, 23B, 2
The pattern width of the sheet coil in the portion adjacent to the core mounting hole 15 can be increased in the order of 3A. Therefore, as the distance from the gap G increases, the resistance of the sheet coil decreases and the energy loss is reduced.

In the above-mentioned embodiment, the case where the secondary coil composed of the sheet coil 24 has two turns is illustrated.
From the relationship with the primary coil composed of the sheet coil 23,
When a plurality of turn coils 24 are provided, the pattern width of the sheet coil 24 adjacent to the core mounting hole 15 is
It is formed so as to gradually become thinner toward the end on the center side.

Further, in the above-described embodiment, the core mounting hole 1
In order to prevent the sheet coil 23B from being provided in the region of the distance W1 in the radial direction from the central axis L of the core 5, the core mounting hole 1
5 illustrates the case where the pattern width of the sheet coil 23B adjacent to No. 5 is gradually narrowed toward the end on the center side. However, the sheet coil 23B does not necessarily have to be formed in this way, and the sheet coil 23B may be provided in a region between the distance W1 and the outer peripheral end of the primary coil substrate 21. That is, the sheet coil 23B having a uniform pattern width may be arranged and formed in this region without changing the number of turns. The same applies to the sheet coil 24.

[0025]

The present invention having the above-mentioned structure has the following effects. That is, the sheet coil is arranged and formed so as to avoid the passage of the magnetic flux of the leakage magnetic field generated from the gap of the core mounted on the laminated sheet coil that constitutes the coil device. Therefore, the eddy current generated in the sheet coil becomes small. Further, since the sheet coil can be arranged adjacent to the core mounting hole as the distance from the gap increases, the pattern width of the sheet coil can be widened. Therefore, the resistance of the sheet coil is reduced. Therefore, the energy loss in the sheet coil is reduced,
A highly efficient coil device can be obtained.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view of a coil device of the present invention.

FIG. 2 is an exploded perspective view of a conventional coil device.

FIG. 3 is a cross-sectional view of a conventional coil device.

FIG. 4 is a diagram showing an arrangement of a primary coil substrate and a secondary coil substrate that form a conventional laminated sheet coil.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Laminated sheet coil 2 Cores 3, 21 Primary coil substrates 4, 22 Secondary coil substrates 5, 9 Insulation substrates 8, 12 Through holes 6, 10, 23A, 23B, 24 Coil sheets 7, 11 Through holes 15 Core mounting hole G gap

Claims (1)

[Claims] 1. A laminated sheet coil in which a plurality of sheet coils are laminated, a core mounting hole provided in the laminated sheet coil, and a core mounted with a gap inside the core mounting hole. A coil device comprising: a coil device, wherein the sheet coil is formed farther from the gap as it is closer to the position of the gap.