JPH0748430B2 - Noise filter - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a noise filter that is inserted in a power supply line or a signal line to prevent noise from entering and leaking.

2. Description of the Related Art A circuit diagram of a conventional general noise filter is shown in FIG. 1 is a common mode choke coil in which a ferrite core or a core made of amorphous metal is provided with a pair of windings on the core so that the magnetic flux due to the reciprocating current is canceled out.
3 is a common mode noise reduction capacitor connected between line grounds, and 4 is a normal mode noise reduction capacitor connected between lines. In a conventional noise filter, a filter circuit is configured by connecting these components on a printed circuit board or directly to the lead wires of each component.

Problems to be Solved by the Invention In the above-described conventional configuration, the number of components is large, the wiring and assembling steps are complicated, and the cost is significantly disadvantageous and the size is increased. Furthermore, the lead wire required for connecting the various capacitors 2 to 4 and the copper foil portion of the printed circuit board are required to be long, and the inductance component increases in series with the capacitor,
The noise prevention effect in the high frequency region was reduced.

As a measure against the above problems, the present invention provides a noise filter having a small number of constituent parts, high productivity, low cost, and high performance.

Means for Solving the Problems In order to solve the above problems, the present invention forms a toroidal core by winding in a ring shape through a ferrite thin film between a plurality of conductive metal foils, and leads from each conductive metal foil. A noise filter is formed by drawing a wire to form a capacitor, and then forming a toroidal winding on a toroidal core to form a coil and connecting them.

Action As described above, by winding a ferrite thin film between a plurality of conductive metal foils to form a toroidal core, and further applying a toroidal winding to the toroidal core, the ferrite thin film exhibits ferromagnetism, so the coil element is Since it can be formed and the ferrite thin film is both a ferromagnetic substance and a dielectric substance, it becomes possible to form capacitor elements between the conductive metal foils by using multiple conductive metal foils as electrodes. In addition, the lead wire is pulled out from the conductive metal foil inside the toroidal core, and the necessary connections such as the coil lead and ground terminal can be made in the shortest distance, which simplifies wiring and assembly. Inductance component can be reduced, noise prevention effect in high frequency area can be improved, downsizing,
Low cost and high performance are possible.

Embodiment An embodiment of the present invention will be described below with reference to the drawings.

1 to 3 are a perspective view of a noise filter in one embodiment of the present invention, an exploded perspective view of a main part, and an enlarged perspective view of the main part. The ferrite thin film 8 is formed on one surface or both surfaces of the three conductive metal foils 5, 6, 7 such as copper foil by a film forming method such as sputtering or vacuum deposition, and the three conductive metal foils 5, 6 are formed. , 7 are stacked so that the conductive metal foils 5 to 7 and the ferrite thin film 8 are alternately located and wound in a ring shape to form a toroidal core 9. From the three conductive metal foils 5,6,7, the lead wire 1
0, 11, 12 are drawn out, the conductive metal foil 6 located in the middle is used as a ground layer, and the drawn lead wire 11 is used as a ground terminal.
Next, as shown in FIG. 1, a copper wire 13 is wound around the toroidal core 9 in a pair of toroidal shapes in a direction in which the magnetic flux due to the reciprocating current is canceled out, and a pair of winding terminals 14 and 15 in the same direction are electrically conductive. A noise filter is configured by connecting terminals 10 and 12 from the conductive metal foils 5 and 7.

That is, a capacitor having the ferrite thin film 8 as a dielectric is formed between the conductive metal foils 5 and 7 and between the conductive metal foils 5 and 7, and the wound ferrite thin film 8 is formed. By forming a coil with a toroidal winding having a core as a core and connecting the coils, a circuit configuration as shown in FIG. 6 can be obtained.

In addition, as shown in FIGS. 4 to 5, the conductive metal foils 5, 6, 7
Even if magnetic metal foils 16, 17, and 18 are used instead, the ferrite thin film 8 is formed on the magnetic metal foils 16 to 18 and wound in a ring shape to form the toroidal core 9 in the same manner as described above.

Lead wires 10, 11 and 12 are drawn out from the three magnetic metal foils 16, 17 and 18, the magnetic metal foil 17 located in the middle is used as a ground layer, and the drawn lead wire 11 is used as a ground terminal. Next, as shown in FIG. 1, a copper wire 13 is wound around the toroidal core 9 in a pair of toroidal shapes in a direction in which the magnetic flux due to the reciprocating current is offset.
A pair of winding terminals 14 and 15 in the same direction and lead wires 10 and 12 from magnetic metal foils 16 and 18 are connected to form a noise filter as shown in FIG. In this case, a coil having the wound ferrite thin film 8 and the magnetic metal foils 16, 17, 18 as a core can be formed, and by combining different materials such as magnetic permeability and frequency characteristics, it is possible to obtain characteristics such as broadband noise attenuation characteristics. It is possible to configure a noise filter.

Furthermore, when the conductivity of the magnetic metal foils 16, 17, 18 is poor, plating the surface of the magnetic metal foils 16, 17, 18 with a good conductive metal reduces the impedance between lines and between line and ground. The noise attenuation characteristic can be improved.

EFFECTS OF THE INVENTION The present invention as described above forms a capacitor inside a toroidal core wound via a ferrite thin film between a plurality of conductive metal foils or between a plurality of magnetic metal foils, and forms a coil on the outer periphery of the toroidal core. Since the noise filter is formed to form the noise filter, the number of parts can be reduced as much as possible, the size can be reduced, and the wiring and the assembly can be easily performed and the cost can be significantly reduced. Also, the length of the lead wire required for connecting various capacitors can be set in the shortest distance, and the noise reduction effect in the high frequency region is improved.

In particular, when a magnetic metal foil is used, a coil having a ferrite thin film having different magnetic characteristics and a magnetic metal foil as a core can be formed, so that a noise filter having a wide band noise reduction effect and the like can be configured. As described above, it has many advantages and is of great industrial value.

[Brief description of drawings]

FIG. 1 is a perspective view of a noise filter according to an embodiment of the present invention, FIG. 2 is an exploded perspective view of a main part of the noise filter according to the embodiment, FIG. 3 is an enlarged perspective view of the same part, and FIG. FIG. 5 is an exploded perspective view of a main part of another embodiment, FIG. 5 is an enlarged perspective view of the main part, and FIG. 6 is an electric circuit diagram of a noise filter. 5,6,7 ... Conductive metal foil, 8 ... Ferrite thin film, 9 ...
… Toroidal core, 10,11,12… lead wire, 13 …… copper wire, 14,15 …… winding terminal, 16,17,18 …… magnetic metal foil.

Claims (3)

[Claims] 1. A toroidal core is formed by winding a plurality of conductive metal foils in a ring shape with a ferrite thin film interposed therebetween, and lead wires are drawn out from each conductive metal foil, and toroidal windings are formed on the toroidal cores. A noise filter configured by applying. 2. A toroidal core is formed by winding a ferrite thin film between a plurality of magnetic metal foils to form a toroidal core, and lead wires are drawn out from each magnetic metal foil, and toroidal windings are applied to the toroidal cores. The configured noise filter. 3. The noise filter according to claim 2, wherein the surface of the magnetic metal foil is plated with a good conductor metal.