JPH0528014U - Common mode chiyoke coil - Google Patents

Abstract

(57) [Summary] [Purpose] To provide a common mode choke coil which has a good noise elimination effect in a high frequency band and can be mass-produced by mechanical winding. [Structure] A primary winding 11 and a secondary winding 12 are wound around a bobbin 1 in a single layer by bifilar winding. The input side ends 11a and 12a of the windings 11 and 12 are soldered to the terminals 6 and 7, and the output side ends 11b and 12b are soldered to the terminals 8 and 9. Further, a rod-shaped core made of ferrite is inserted into the center hole of the bobbin 1.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to a common mode choke coil used as a noise countermeasure in a high frequency band (30 MHz to 1 GHz).

[0002]

[Prior Art]

 Conventionally, the common mode choke coil shown in FIG. 4 has been used to remove asymmetrical component noise (common mode noise) that flows between the power line of an electronic device and the ground. This choke coil is formed by bifilarly winding an annular toroidal core 25 with a primary winding 26 and a secondary winding 27 made of copper wire coated with polyurethane.

However, in this type of common mode choke coil, since the winding ends of the terminals on the input side and the output side are close to each other, the stray capacitance between the windings increases and the noise attenuation characteristic in the high frequency band deteriorates. Had problems. Moreover, since the winding work cannot be done mechanically and is done manually, the productivity is poor and the cost is increased.

[0004]

[Purpose, configuration, operation of the device]

 Therefore, an object of the present invention is to provide a common mode choke coil which has a good noise removal effect in a high frequency band and can be mass-produced by mechanical winding. In order to achieve the above object, the common mode choke coil according to the present invention has a single-layer bifilar winding of a primary winding and a secondary winding around a rod-shaped core made of a high-resistivity magnetic material. Is characterized by.

Since the winding is wound around a rod-shaped core, the winding is coupled with high density in combination with the bifilar winding, and the distance between the winding ends of the winding start and the winding end becomes large, so that the line stray capacitance is reduced. This reduces the problem of bypassing high frequency common mode noise and improves high frequency characteristics. In addition, a bobbin can be used, and if the winding work is done mechanically, mass productivity will be improved.

Further, stray capacitance is generated between different poles on the input side and the output side of the winding, and the stray capacitance causes symmetric component noise (normal mode noise) that is superimposed on the load current and reciprocates between power lines. To be removed.

[0007]

【Example】

 An embodiment of a common mode choke coil according to the present invention will be described below with reference to the accompanying drawings. 1 and 2, the common mode choke coil includes a bobbin 1, a rod-shaped core 5 inserted into the center hole 2 of the bobbin 1, a primary winding 11 and a secondary winding wound around the outer peripheral surface of the bobbin 1. And winding 12.

The windings 11 and 12 are made of polyurethane-coated copper wire, and are wound around the outer peripheral surface of the bobbin 1 in a single layer by bifilar winding. Although the number of turns varies depending on the target frequency band, it is set to 20 in this embodiment. Input side terminals 6 and 7 and output side terminals 8 and 9 are attached to the flanges 3 and 4 provided at both ends of the bobbin 1. The input side end 11 a of the primary winding 11 is connected (soldered) to the input side terminal 6, and the output side end 11 b is connected to the output side terminal 8. The input side end 12 a of the secondary winding 12 is connected to the input side terminal 7, and the output side end 12 b is connected to the output side terminal 9.

The rod-shaped core 5 is made of a magnetic material having a high resistivity, specifically, a Ni—Zn type ferrite having a magnetic permeability μi of about 550, and the center hole 2 of the bobbin 1 around which the winding wires 11 and 12 are wound. Is inserted into. In the common mode choke coil configured as described above, the input side terminals 6 and 7 are connected to the power source, the output side terminals 8 and 9 are connected to the electronic device, respectively, and a common common applied to the primary winding 11 and the secondary winding 12. Remove mode noise. Since the windings 11 and 12 are wound in a single layer, and the output side and the input side are largely separated from each other, the stray capacitance between lines becomes small, and there is no fear that high frequency noise will be bypassed. Further, stray capacitance is also generated between terminals 6 and 7 and between 8 and 9, and this capacitance has a function of letting out normal mode noise that reciprocates between windings 11 and 12 to the earth line.

Further, by using the rod-shaped core 5 having a high resistivity, the high frequency characteristics are improved, and by using the bobbin 1, the windings 11 and 12 can be mechanically wound by an automatic winding machine. , Mass productivity is improved. FIG. 3 shows the attenuation characteristic of high frequency noise, and curve A shows the attenuation characteristic of common mode noise in the product of the present invention. Curve B shows the attenuation characteristic of normal mode noise in the present invention. For comparison, a curve C shows the attenuation characteristic of common mode noise in the conventional product shown in FIG. Note that these common mode choke coils are designed as a countermeasure against noise in the 30.0 to 1000 MHz band.

The common mode choke coil according to the present invention is not limited to the above embodiment, but can be variously modified within the scope of the gist thereof. For example, the primary winding and the secondary winding may be directly wound around the rod-shaped core. In this case, it is preferable to form an electrode by applying a conductive paste to the core instead of the terminal and baking it.

[0012]

[Effect of the device]

 As is clear from the above explanation, according to this consideration, since the primary winding and the secondary winding are wound in a single layer around the rod-shaped core, the winding start and end distances are large. Therefore, the stray capacitance between lines is reduced, the high-frequency common-mode noise attenuation characteristics are improved, and the normal mode noise can also be attenuated by the stray capacitance generated between the different poles of the winding. Also, mechanical winding of the winding is possible, mass productivity is improved, and production cost is reduced.

[Brief description of drawings]

FIG. 1 is a bottom view showing an embodiment of a common mode choke coil according to the present invention.

FIG. 2 is a perspective view showing a bobbin and a core of the common mode choke coil shown in FIG.

FIG. 3 is a graph showing attenuation characteristics of high frequency noise components.

FIG. 4 is a perspective view of a conventional common mode choke coil.

[Explanation of symbols]

 1 ... Bobbin 5 ... Rod-shaped core 11 ... Primary winding 12 ... Secondary winding

Claims (1)

[Scope of utility model registration request] 1. A common mode choke coil characterized in that a primary winding and a secondary winding are bifilarly wound in a single layer around a rod-shaped core made of a magnetic material having a high resistivity.