JPS6123309A - Choke coil - Google Patents

Abstract

PURPOSE:To obtain the titled item which is improved D.C. superposition property and miniaturized and is low-cost by a method wherein a toroidal shaped magnetic material installed a groove intersecting partially with an annular face between two isolating plates, is held and printed wiring and the like is performed. CONSTITUTION:A toroidal shaped magnetic material 13 which is installed a groove intersecting partially with an annular face between the isolating plate 11, 12 and an isolating material 15 is filled to the other portion between the isolating plate 11, 12, then a printed wiring 16, 17 is treated by metal on the surface of the isolating plate 11, 12 respectively. After that, the throughhole 18 and the like connecting between the printed wirings 16, 17 is provided and facilitated to connect with the other circuit which is performed printed wiring on the surface of the isolating plate 11, 12. Additionally, inductance of a choke coil is trimmed to make the property increase greatly as the result of decreasing D.C. superposed current. By this fact, as the printed wiring is able to be produced simultaneously with the other circuit wiring in the state of one body by applying the technique of the printed wiring, assembly man-hour is unnecessitated and then it is possible to be low-cost and miniaturized.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field] The present invention relates to a choke coil that is used in a filter circuit of a high-frequency switching regulator and has characteristics that improve output voltage fluctuation characteristics with respect to load fluctuations during light loads.

[Prior art]

The choke coils conventionally used in switching regulators are small and have toroidal cores with low leakage flux, and are made of core materials with good DC current superimposition characteristics (
It uses a molybdenum permalloy core, etc., and has a winding structure as shown in FIG. In Figure 4, 1 is the bore, 2
indicates a winding.

FIG. 5 is a diagram showing the DC superimposition characteristics of the choke coil shown in FIG. 4, and the inductance has a constant value up to a certain DC current value.

However, in the current situation where demands for low cost and miniaturization of switching regulators are increasing, switching regulators are being made to have higher frequencies as a means to meet these demands. When using a choke coil having the above structure, it has been difficult to satisfy the demand for low cost and miniaturization due to the large space required and the need to manually wind the coil. Furthermore, when a choke coil constructed using the conventional method is used in a filter circuit of a switching regulator, when the load of the switching regulator fluctuates and the output current decreases, the current flowing through the choke coil becomes discontinuous, and as a result, the output voltage The disadvantages are that the stability of the output voltage deteriorates and the ripple voltage component of the output voltage increases.

[Purpose of the invention]

The purpose of the present invention is to eliminate these drawbacks by improving the DC current superposition characteristics so that the inductance increases when the DC superimposed current flowing through the choke coil is small and has a simple structure of printed wiring. The purpose of the present invention is to provide a small and low-cost choke coil.

[Structure of the invention]

In the present invention, a choke coil has a toroidal J-shaped magnetic material with a groove partially intersecting an annular surface sandwiched between two insulating plates, and the remaining part between the two insulating plates is sandwiched between two insulating plates. The portion is filled with an insulating material, the surface of each insulating plate is printed with metal wiring, the printed wiring on each surface is connected by a metal wiring in a through hole that penetrates both, and The structure is such that the terminals of the metal printed wiring on both insulating plates can be easily connected to other circuits printed with metal on the surfaces of both insulating plates.

〔Example〕

Next, an embodiment of the choke coil according to the present invention having the above configuration will be described.

1 and 2 are diagrams of a choke coil according to an embodiment of the present invention, and FIG. 1 shows the ml of the choke coil assembly.
The fM diagram and FIG. 2 are diagrams in which it is disassembled into two insulating plates and other parts. In these figures, 11 and 12 are insulating plates, 1B is a toroidal magnetic material, 14 is a groove (gap) intersecting the annular surface, 15 is an insulating material, and 16-
1. 16-2 to 16-0 are metal printed wirings on the surface of the insulating plate 11 (hereinafter referred to as 16-n patterns).

) 17-1, 17-2 to 1.7-n is a metal printed wiring on the surface of the insulating plate of 12 (hereinafter referred to as a turn of 17-n), 18-1, 18-2 to 18 -n
is a metal wiring structure (J2 is referred to as the lower through hole 18-n) connecting the pattern 16-n and the pattern 17-n.

16-1 pattern and 17-1 pattern are 18-
Connected via 1 through hole. At the same time 17-1
The pattern is 16- through the 18-2 through hole.
This means that the magnetic material 18 is wound once around the pattern 16-1, 17-1 and the through hole 18-1. Similarly, 16-n, 1? By sequentially connecting the -n pattern and the 18-n through hole, windings are formed one after another and the necessary inductance can be obtained.

And the first and last patterns, for example, 16-1
pattern, 17-n's turn terminal, 11.
The other circuit of printed wiring made of metal on an insulating plate in No. 12 is as follows:
Can be easily connected.

Next, the DC superimposition characteristics will be explained with reference to FIGS. 2 and 8. In FIG. 2, 18 is divided into two parts, 1B-1 is a continuous annular magnetic material, and 18-2 is a magnetic material having a gap intersecting the annular surface. The characteristics of a choke coil having a wire-wound structure are as follows: First, when the DC superimposed current flowing through the choke coil is less than the DC superimposed current value at which the continuous annular magnetic material of 1B-1 does not magnetically saturate, the continuous annular magnetic material of 1B-1 The inductance is determined by the sum of the magnetic permeability of the magnetic material part of 18-2 and the magnetic material part with a gap of 18-2, and the inductance as a choke coil is
The DC current in the figure takes a corresponding value H1 between 0 and I.

Next, when the DC superimposed current flowing through the choke coil increases and the continuous annular magnetic material 1B-1 becomes magnetically saturated, the choke coil moves the magnetic material 1B-1 having a gap.
It has an inductance determined by a magnetic permeability of 2, and the DC current in FIG. 8 has a value H, which corresponds to between 11 and I. Therefore, when this choke coil is used in the filter circuit of a switching regulator that has DC superposition characteristics as shown in Figure 8, even if the load of the switching regulator fluctuates and the output current decreases, the current will flow to the choke coil. Since the current is discontinuous (h76), the stability of the output voltage does not deteriorate and the ripple component of the output voltage is less likely to increase.

〔Effect of the invention〕

According to the present invention, choke coils, which were conventionally wound by hand, can be manufactured by applying printed wiring technology and being integrated with other circuit wiring at the same time, eliminating the need for assembly man-hours and reducing costs. We can provide choke coils that meet the demands for price and miniaturization.

In addition, the choke coil obtained in this way has the characteristic that its inductance increases greatly as the DC superimposed current decreases, so even if the current flowing through the choke coil decreases due to load fluctuations, the choke coil The effect is that the current flowing through the coil is less likely to become discontinuous, the stability of the output is not degraded, and the ripple component of the output voltage is less likely to increase.

[Brief explanation of the drawing]

FIG. 1 is a perspective view of a choke coil assembly according to the present invention, FIG. 2 is a perspective view of the choke coil assembly divided into insulating plates and other parts, and FIG. 8 is a perspective view of the choke coil assembly according to the present invention. DC superimposed current characteristic graph. Figure $4 - A perspective view of a conventional choke coil assembly;
Figure 4-B is a top view showing the winding state of the magnetic material;
The figure is a DC superimposed current characteristic graph of a conventional choke coil. 1...Magnetic material 2...
...winding wire. 11.12...Insulating board. 1B (1B-1, 18-2)...Magnetic material. 14...Groove (gap). 15...Insulating material. 18-1.18-2~18-n ・・・・・・・・・
Through hole. Patent Applicant NEC Corporation Figure 1 1'/ Figure 2 0 If I2 Direct Water Current (△) Figure 3 Figure 4 - Date

Claims (1)

[Claims] A toroidal-shaped magnetic material having a groove partially intersecting an annular surface is sandwiched between two insulating plates, and the other part between the insulating plates is filled with an insulating material. , metal printed wiring is provided on the surface of each insulating plate, and has a structure for connecting the printed wiring, and is connected to other circuits printed on the surfaces of the two insulating plates. 1. A choke coil having a simple structure, characterized in that the inductance of the choke coil increases significantly as a DC superimposed current decreases.