JPS605625Y2 - noise filter - Google Patents

Description

[Detailed description of the invention] The present invention is a noise filter in which at least two metal foils for conducting current are stacked together with an insulating sheet having a high dielectric constant interposed therebetween, and the layers are wound to obtain inductance and capacitance. In this regard, an attempt is made to reduce costs by winding a grounding electrode foil around the outer periphery of the wound body to stabilize characteristics and improve productivity.

Conventional noise filters have been constructed by attaching a coil made of wound wire to a magnetic core, and connecting a capacitor to this coil.

A noise filter with this configuration has disadvantages in that it has many components, is disadvantageous in terms of cost, requires time and effort to assemble, and is large in size.

For this reason, recently, two current-carrying electrode foils made of metal foils such as aluminum or body are stacked with an insulating sheet made of polyester or polyethylene with a high dielectric constant interposed between them, and these are rolled into a cylindrical shape. Noise filters with inductance and capacitance are being developed, which are constructed by forming a coil into a magnetic core made of ferrite or the like.

Furthermore, as shown in FIG. 1, a strip of metal foil made of the same material is formed between two current-carrying electrode foils 1 and 2 with an insulating sheet 3 interposed therebetween, and is wound several times. A coil 5 is obtained by stacking the grounding electrode foil 4 cut into a plurality of pieces into a cylindrical shape, sandwiching the grounding electrode foil 4, which is cut into a plurality of pieces into a coil 5. A noise filter has been developed in which a lead wire 6 is drawn out from the foil 4 and attached to a mouth-shaped magnetic core 7 made of ferrite or the like, and which has excellent ferrite characteristics even in a high frequency range.

The electrical equivalent circuit diagram of the noise filter with such a configuration is shown in FIG. 2, and in FIG. 2, L is the inductance l obtained by the current-carrying electrode foils 1 and 2.
, / is the inductance obtained by the grounding electrode foil 4, C is the inductance obtained between the current-carrying electrode foil 1°2 or the current-carrying electrode foil 1,
2 and the grounding electrode foil 4.

In a noise filter having such a configuration, unnecessary inductance L' caused by the grounding electrode foil 4 causes unnecessary resonance in the damping characteristics, making it impossible to obtain excellent damping characteristics. Since the grounding electrode foil 4 is inserted over the whole area, productivity is poor, and
It had the disadvantage of being large.

The present invention eliminates the above-mentioned drawbacks of noise filters.

Embodiments of the present invention will be described below with reference to FIGS. 3 to 6.

First, in FIGS. 3 and 4, reference numeral 8 denotes a magnetic core that constitutes a square-shaped open magnetic path by abutting UtJ-shaped or U-shaped ferrite magnetic cores, and the magnetic legs of this magnetic core 8 are made of polyester or polyethylene. Insulating sheet with high dielectric constant such as 9.10
The current-carrying electrode foils 11 and 12 made of metal foils with a thickness of about 0.02 m, such as aluminum or shells, are stacked up with a metal foil of about 0.02 m in thickness interposed between the electrode foils 11 and 12, which are wound into a cylindrical shape. A coil 15 is attached, which is constructed by wrapping a grounding electrode foil 13 made of thin metal foil such as a body and covering the outer periphery with an insulating sheet 14.

Lead wires 16 to 19 are drawn out from the winding start and end of the current-carrying electrode foil 11 and 12, respectively, and a lead wire 20 is drawn out from the grounding electrode foil 13 as well.

The electrical equivalent circuit diagram of the noise filter constructed in this manner is shown in FIG. 5.

That is, Li, C2 is the inductance obtained by the current-carrying electrode foil 11.12, and C is the current-carrying electrode foil 11,1.
2 questions and energizing electrode foil 11.12 and grounding electrode foil 13
This is the capacitance obtained between the grounding electrode foil 1
3 simply wraps around the outer circumference of the wound body once, so
Unnecessary inductance becomes negligible.

Therefore, in the attenuation characteristics of the noise filter, unnecessary resonance caused by unnecessary 2f inductance can be prevented, and excellent attenuation characteristics can be achieved.

In addition, in the above embodiment, the current-carrying electrode foil 11.12
Although the width of the grounding electrode foil 13 was not particularly mentioned in the above, the above-mentioned effect can be obtained even if the width of the grounding electrode foil 13 is narrower than the width of the current-carrying electrode foil IL 12, as shown in FIG.

However, as shown in FIG. 6, by configuring the width of the grounding electrode foil 13 to be wider than the width of the current-carrying electrode foil 11 and 12, an electrostatic shielding effect is added, and the influence of radiated noise can be eliminated. It can be made more effective.

As described above, in the noise filter of the present invention, the grounding electrode foil used to improve characteristics in the high frequency range is wound only around the outermost part, so the winding length of this grounding electrode foil is short. This eliminates unnecessary inductance, prevents unnecessary resonance in the damping characteristics, and provides excellent characteristics.Moreover, the grounding electrode foil is only wound around the outermost part. This makes winding work easier, making it possible to downsize the entire product, and also reducing material costs and reducing costs.It also acts as an electrostatic shield, reducing the effects of radiated noise. It has the advantage of being completely free, and has great practical value.

[Brief explanation of drawings]

Fig. 1 is a partially exploded perspective view of a noise filter that has been developed recently, Fig. 2 is an electrical equivalent circuit diagram of the same, Fig. 3 is a perspective view showing an embodiment of the noise filter of the present invention, and Fig. 4 5 is a partially exploded perspective view of the same coil, FIG. 5 is an electrical equivalent circuit diagram of the same noise filter, and FIG. 6 is a perspective view showing a noise filter of another embodiment. 8...Magnetic core, 9,10...Insulating sheet, 11゜12...Electrifying electrode foil, 13...
...Grounding electrode foil, 14...Insulating sheet.

Claims (2)

[Scope of utility model registration request] (1) In a noise filter configured to obtain inductance and capacitance by winding a stack of two metal foil current-carrying electrode foils through an insulating sheet with a high dielectric constant, the insulating sheet and current-carrying electrode A noise filter consisting of a grounding electrode foil wrapped around the outermost periphery of the foil. (2) The noise filter according to claim 1, wherein the grounding electrode foil is wider than the current-carrying electrode foil.