JPH0124901Y2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to a noise filter integrally constructed using a magnetic circuit board.

2. Description of the Related Art As is well known, as the application technology of semiconductor devices progresses, the protection function against harmful noise and the suppressing function against generated noise in electronic equipment have become serious problems. In digital devices, even very narrow noise can cause malfunctions, and in power control devices, large noises are caused by step-shaped currents that flow during switching of semiconductor devices. Therefore, recently,
There is a tendency for noise filters to be installed in almost all digital equipment.

However, conventional noise filters generally have a configuration in which discrete components such as coils and capacitors are mounted on a printed circuit board, external leads are pulled out, and the structure is housed in a case.As a result, they are inevitably large and difficult to assemble. It's tedious and difficult to reduce costs.

As mentioned above, noise filters are now being incorporated into all kinds of electronic devices, and noise filters, especially those with relatively small current capacities, are small and thin, easy to incorporate into devices and handle, and are inexpensive. A noise filter is required.

The present invention aims to provide such a noise filter.

That is, the present invention uses a substrate having a structure in which a plurality of opposing notches are formed in a plate-shaped magnetic material, a conductive pattern is formed on the substrate, a coil is provided in each of the notches, and these coils are The noise filter is configured such that adjacent coils generate magnetic fields in opposite directions, a capacitor is mounted on the substrate, internal wiring is made using the conductive pattern, and external lead pins are connected. .

Hereinafter, one embodiment of the present invention will be described in detail based on the drawings. FIG. 1 shows an example of a basic circuit of a noise filter, which is composed of two coils L1, L2 and three capacitors C1, C2, C3.

Each terminal is a, b is the power supply side, c is the ground, d,
e is the load (equipment) side.

An example of the noise filter according to the present invention is shown in FIG. 2. This embodiment is an example of realizing the circuit shown in FIG. 1. The substrate 1 is made of a plate-shaped magnetic material, and has a structure in which a set of notches 2 are formed in the width direction at both ends thereof so as to face each other from both sides. For example, ferrite is suitable as a plate-shaped magnetic material, and in that case, it may be press-molded into a desired shape and sintered, or it may be punched or cut into a desired shape in a green state and sintered. Good too. Although it is possible to perform cutting after sintering, this is generally difficult and disadvantageous.

If the surface insulation resistance of the substrate 1 is sufficiently high, the desired circuit pattern 3 may be formed directly on the surface of the substrate. The circuit pattern 3 can be formed using, for example, a conventionally known technique such as screen printing. If the surface insulation resistance of the substrate 1 is low, an insulating film may be formed on the surface of the substrate, and the circuit pattern 3 may be formed thereon. Circuit pattern 3 includes installing a capacitor and coils L1 and L.
In addition to lands and wiring patterns for processing the terminals of No. 2, it has lands for attaching external lead pins 6, etc.

Coils L are installed in the notches 2 at both ends of the board 1.
1, L2 is formed. In this case, each coil is
The magnetic fields generated therefrom are arranged in opposite directions. Because of this configuration, the winding directions of these coils L1 and L2 as well as the substrates L1 and
It goes without saying that the direction of the current flowing through L2 may be appropriately set. Further, the terminals of these coils L1 and L2 are connected to lands or the like of the circuit pattern 3 formed on the substrate 1. The formation of the coil can be easily automated since it is only necessary to wind the wire in the cut portion. Also,
On such a substrate 1, there are three capacitors C1,
C2 and C3 are mounted and connected using the conductive pattern 3. The capacitor used may be a normal discrete component, but if a chip component is used as in this embodiment, the capacitor can be made thinner. Furthermore, external lead pins 6 are attached using the conductive pattern 3. As shown in FIG. 2, a single-in-line type package can be obtained by lining up the external lead pins 6 on only one side and pulling them out. Finally, by molding the board on which the components are mounted or by enclosing it in a case, an easy-to-handle noise filter can be obtained.

FIG. 3 shows the direction of the magnetic field generated by both coils. In order to make the drawings easier to read, descriptions of circuit patterns, capacitors, etc. are omitted. When the substrate 1 is made of ferrite with a small saturation magnetic flux density, the notch is used as a gap to prevent saturation.
With respect to noise, it is possible to improve the effect of normal mode removal, and since the magnetic fields generated from each coil are configured to be in opposite directions, coupling between the coils can be eliminated.

Although a preferred embodiment of the present invention has been described in detail above, it goes without saying that the present invention is not limited to this configuration and can be modified in various ways.

Since the present invention is a noise filter configured as described above, it is suitable for miniaturization and thinning, is easy to incorporate into equipment and handle, and is also suitable for automatic assembly and can be manufactured at low cost, making it practical. The effect is very large.

[Brief explanation of drawings]

FIG. 1 is a circuit diagram showing a typical example of a noise filter, FIG. 2 is an explanatory diagram showing an embodiment of the present invention, and FIG. 3 is an explanatory diagram showing an example of the direction of the magnetic field. L1, L2...Coil, C1, C2, C3...
Capacitor, 1... Board, 2... Notch, 3...
...Circuit pattern.

Claims (1)

[Scope of utility model registration request] Using a substrate having a structure in which a plurality of opposing notches are formed in a plate-shaped magnetic material, a conductive pattern is formed on the substrate, and a coil is provided in each of the notches,
In addition, these coils are configured so that adjacent coils generate magnetic fields in opposite directions, and a capacitor is mounted on the board, internal wiring is made using the conductive pattern, and lead pins for external extraction are connected. noise filter.