JPH058661Y2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to a noise filter that prevents interference to telephones or terminal equipment due to radio wave induction such as medium wave broadcast waves and CB radio waves to telephone lines.

Conventionally, methods for preventing this type of radio wave induced interference include inserting a capacitor between the line and ground to bypass it, inserting an inductor into the line to prevent interference waves from entering, or inserting an induct and a capacitor. Was.

However, when using a capacitor, it is troublesome to connect it to the ground, and the ground wire becomes an antenna, reducing the prevention effect.

Also, when inserting an inductor into each line of a telephone line, the impedance of the filter is high (e.g.
Approximately 60KΩ at 1MHz, 9.5mH in inductance
Therefore, in the case of pulse transmission, the transmission characteristics deteriorate, and it is difficult to maintain a balance between the two telephone lines.

On the other hand, interference voltages have also been eliminated by inserting a common mode choke coil into the telephone line. The inductance of a common mode choke coil is 1/2 that of inserting an inductor in each line (for example, about 30KΩ at 1MHz), and the common mode choke coil has the advantage of not affecting the signal. . Therefore, the common mode chiyoke coil is suitable as a chiyoke coil that prevents this kind of induced noise. However, since conventional common mode choke coils are wound around a toroidal core, the winding work is troublesome and expensive. There was a problem with having to insert the chiyoke coil into the telephone line.

An object of the present invention is to provide a chiyoke coil that is less expensive than conventional common mode chiyoke coils and prevents broadband induction noise.

The present invention is a chiyoke coil that prevents radio wave interference induced in telephone lines to which telephones and data communication equipment are connected.The present invention is based on a system in which multiple drum-shaped cores with annular grooves formed on the outer periphery of a rod-shaped core are connected in the axial direction. This is a chiyoke coil for preventing induced noise in telephone lines, which is characterized by comprising a shaped core and windings sequentially wound by bifilar winding in a plurality of annular grooves on the outer periphery of the core.

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 shows an embodiment of the present invention, in which two drum-shaped cores 1 and 2, whose flanges have the same outer diameter and thickness and whose annular grooves 11 and 21 have different dimensions, are arranged in the axial direction. This is a chain-yoke coil in which the windings 3 and 4 are overlapped and integrated, and the windings 3 and 4 are bifilar-wound first in the groove 11 and then in the groove 21 with the polarities in the same direction.

The characteristics of this choke coil are closely related to the shape and dimensions of the drum-shaped core, and an example of this for medium waves is shown in FIG. That is, it can be seen that the smaller the width W of the groove, the higher the inductance and the smaller the capacitance, so it is desirable to make it smaller. However, in order to obtain high impedance, it is necessary to have a large number of windings, and considering the wire diameter (for example, having a maximum current withstand capacity of 100 mA), for example, about 4 mm can be selected. The deeper the groove depth H (see Figure 1), the higher the inductance and the smaller the capacitance. The depth should be such that the diameter of the hole is about 3 to 4 mm. Further, the larger the outer diameter of the core (diameter of the flange), the higher the inductance, so the larger the diameter, the better.
However, considering the mounting dimensions, it is selected to be 15 mm or less, for example.

The coil consisting of windings 3 and 4 wound on core 1 is a choke coil that prevents interference in medium waves, and the coil CB consisting of windings 3 and 4 wound on core 2 prevents interference. This is a chiyoke coil that prevents this.

A chi-yoke coil having such a structure is inexpensive because the winding operation can be easily performed continuously in the two grooves 11 and 21, and wide-band induction noise can be prevented as shown in FIG.

The chiyoke coil shown in FIG. 4 shows another embodiment of the present invention, in which the drum-shaped cores 1 and 2 in FIG. be.

Alternatively, a magnetic tape (permalloy, amorphous, etc.) may be wound around the outer circumference of one of the coils, and a broadband noise prevention coil can be realized by combining two coils.

As is clear from the description of the above embodiments, according to the present invention, it is possible to obtain a chiyoke coil for preventing induction noise in a telephone line, which is easy to wind, is inexpensive, and can prevent induction noise in a wide band.

[Brief explanation of the drawing]

FIG. 1 is a perspective view showing an embodiment of the present invention;
Figure 2 is a frequency characteristic diagram of the groove width and impedance of the drum-shaped core at medium waves, Figure 3 is a diagram showing the impedance characteristic of the embodiment of Figure 1, and Figure 4 is a diagram of another embodiment of the present invention. FIG. 1, 2...Drum-shaped core, 3, 4...Winding, 5
...Drum-shaped integral core, 11, 21, 51, 52
...Annular groove, W...Groove width, H...Groove depth.

Claims (1)

[Scope of utility model registration request] A chiyoke coil that prevents radio interference induced in telephone lines to which telephones and data communication equipment are connected includes a drum-shaped core in which a plurality of annular grooves with different groove widths are formed on the outer periphery of a rod-shaped core, and A chiyoke coil for preventing induced noise in telephone lines, characterized by comprising windings sequentially wound by bifilar winding in a plurality of annular grooves on the outer periphery.