JPH05291865A - Lc filter - Google Patents

Abstract

PURPOSE:To provide an excellent attenuation performance comprising an L and a C component only and to obtain an LC filter with simple configuration at a low cost by winding plural conductor wires arranged closely so as to be insulated with each other in a coil form and using at least two of the plural conductor wires as conduction conductors. CONSTITUTION:Two electric cords 10-1, 10-2 are wired in parallel. The electric cords 10-1, 10-2 are formed by giving a sheath to a conductor wire 12 made of a copper wire or the like with an insulator 13. An LC filter is formed by winding the two electric cords 10-1,10-2 to be a coil in spiral. In this case, an integrated flat parallel cord may be used for the two electric cords 10-1,10-2 or two electric cords 10-1, 10-2 independent of each other may be wound in parallel.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an LC filter, and more particularly to an LC filter formed by using a plurality of conductive lines.

[0002]

2. Description of the Related Art As is well known, a large number of IC elements are used in various electronic / electrical devices today, and in particular, with the development of electronic technology in recent years, a large number of high performance ICs in various electronic devices. The element is being used. Therefore, interference is prevented from being generated from the terminal lines of each of these IC elements to the surroundings, and the operation of the high-performance IC element is not disturbed by the interference waves generated from other electronic devices. Regulations on the waves are getting severer year by year.

Therefore, a noise filter is connected to the electronic circuit of the device to be regulated, particularly the terminal line of the IC element used in this electronic device, the noise components flowing on these IC lines are removed, and the interference wave is removed. Measures are also being taken to suppress this.

[0004]

However, most of the conventional LC filters are simply a combination of discrete components such as a capacitor and a coil, and are of a one-chip type that can obtain good attenuation characteristics with a simple structure. There was no LC filter.

In particular, in the conventional LC filter, there is no technique for easily making an LC filter having a good attenuation characteristic by using a wire material such as an electric wire, and an improvement thereof has been desired.

The present invention has been made in view of such conventional problems, and an object thereof is to provide an LC filter using a conductive wire and having a simple structure and good attenuation characteristics. ..

[0007]

In order to achieve the above-mentioned object, the present invention is formed by winding a plurality of conductive wires adjacent to each other so as to be insulated from each other in a coil shape.
At least two of the plurality of conductive wires are formed as current-carrying conductors.

According to the present invention, a plurality of conductive wires that are adjacently arranged so as to be insulated from each other are wound in a coil shape, and at least one of the plurality of conductive wires is formed as a current-carrying conductor. At least one of the plurality of conductive lines is formed as a ground conductor.

[0009]

With the above structure, in the LC filter of the present invention, the plurality of conductive wires formed by winding in a coil function as inductors. In addition, the plurality of conductive wires are arranged adjacent to each other in a bundle so as to be insulated from each other. Therefore, a capacitance is formed in a distributed constant manner between the conductive lines, or a capacitance due to the floating capacitance is formed in each conductive line.

Therefore, when at least two conductive wires are used as the current-carrying conductors as in the LC filter of claim 1, the LC filter functions as an LC noise filter having at least four input / output terminals.

In addition, like the LC filter of claim 2,
By using at least one of the conductive wires as a current-carrying conductor and using at least another one of the conductive wires as a ground conductor, it is possible to form, for example, a three-terminal type LC filter.

In particular, according to the present invention, the LC filter can be formed by winding a plurality of conductive wires, which are arranged adjacent to each other in a bundle in a state of being insulated, into a coil shape to form an LC filter. It will be extremely simple and inexpensive.

Further, the plurality of conductive wires are wound in a coil shape to function as an inductor, and the capacitance is effectively distributed by the capacitance formed in a distributed constant between these inductors or the floating capacitance formed in each inductor. Therefore, it functions as an LC filter having a good attenuation characteristic as a whole.

In addition to this, since the LC filter of the present invention can be formed as a one-chip element, the cost thereof can be significantly reduced as compared with the case where the LC filter is composed of a plurality of discrete components such as a coil and a capacitor. it can.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT A preferred embodiment of the present invention will now be described in detail with reference to the drawings.

First Embodiment FIG . 1 shows a preferred embodiment of an LC noise filter to which the present invention is applied. When manufacturing the LC filter of the embodiment, as shown in FIG. 1A, two electric wire cords 10-1 and 10-2 are arranged in parallel with each other. Each electric wire cord 10-1 and 10-2 is shown in FIG.
As shown in the cross-sectional view of FIG.
Is formed by covering the surface of the with an insulator 13.

The two electric wire cords 10-1 and 10-2 arranged in parallel are wound in a spiral coil shape as shown in FIG.
Form a filter.

At this time, the two electric wire cords 10-
As 1 and 10-2, ones which are previously formed as an integral type parallel cord connected to each other may be used, or two independently formed electric wire cords 10-1 and 10-2 are arranged in parallel and wound. It may be formed by turning.

Then, the electric wire cords of the LC filter thus formed are fixed to each other by self-bonding or an adhesive agent, so that the shape of the electric wire cord can be prevented.

FIG. 7A shows an equivalent circuit diagram of the 4-terminal LC noise filter thus formed. Since each of the conductive wires 12-1 and 12-2 is wound in the shape of a spiral coil,
Each of which functions as an inductor L _1, L _2. Moreover, these are the conductive wires 12-1 and 12-2, the insulator 13
The capacitance C is formed in a distributed constant manner between the two because they are opposed to each other in parallel. In addition, a capacitance such as a floating capacitance is also formed around these conductive lines 12-1 and 12-2.

Therefore, these conductive lines 12-1, 12-2
At both ends of the input / output terminals 14a, 14b, 14
By providing c and 14d, it is possible to obtain a 4-terminal LC filter having good attenuation characteristics of L and C.

Particularly, in the LC filter of the embodiment, only 2
Since the electric wire cords 10-1 and 10-2 of the book can be formed only by arranging them in parallel and winding them around each other, the structure thereof is simple and inexpensive.

Further, as shown in FIG. 7B, input / output terminals 14a and 14b are provided only at both ends of one conductive line 12-1 of the LC filter shown in FIG. 1, and the other conductive line 12-2 is provided. By providing the ground terminal 14c only on one end side thereof, it is possible to obtain a three-terminal LC filter having good attenuation characteristics.

When forming such a three-terminal type LC filter, it is an important problem to obtain a good attenuation characteristic as to where the ground terminal 14c is formed with respect to the input terminals 14a and 14b. .. According to an experiment by the present inventor, the ground terminal 14c is arranged with respect to the one input terminal 14a in terms of circuit arrangement
It has been confirmed that the closer they are to each other, the better the attenuation characteristics of the filter.

FIG. 8A shows one input / output terminal 14a.
Is set as the reference position 0, and the ground terminal 14 is placed at this reference position.
The state of forming c is shown. Then, the position of the ground terminal 14c is set to the reference position 0 as shown in FIG.
When the LC filter is formed in the same manner as in the above embodiment, the attenuation characteristics of the noise filter are measured. Fell. In the experiment,
Good attenuation characteristics could be obtained by bringing the distance between the ground terminal 14c and the input / output terminal 14a close to each other within at least several percent of the distance between the input / output terminals 14a and 14b.

In consideration of such experimental results, in the embodiment, the ground terminal 14c is formed at substantially the same position as one of the input / output terminals 14a so that good attenuation characteristics can be obtained.

Further, as shown in FIG. 7C, an example in which the grounding conductive wire 12 is divided into two parts 12-2a and 12-2b is shown. In this case, one ground terminal 1
It is preferable that 4c is arranged close to the input / output terminal 14a in terms of circuit arrangement and the other ground terminal 14d is arranged close to the other input / output terminal 14b in terms of circuit arrangement.

Further, as shown in FIG. 7D, the conductive wire 12
It is also conceivable to divide -2 into three or more pieces such as 12-2a, 12-2b, 12-2c and use these as ground conductors. In this case, each divided ground conductor 12
The end portion on the side closer to the input / output terminal 14 may be connected to the ground terminal 14c or 14d provided near the input / output terminal. For example, taking the divided conductor 12-2c as an example, in the conductive wire 12-2c, the distance between the left end portion and the input / output terminal 14a is greater than the distance between the right end portion and the input / output terminal 14b in terms of circuit layout. It's short. Therefore, the divided conductor 12-2c is formed so that the left end thereof is connected to the ground terminal 14c. By doing so, even when the grounding conductive wire 12-2 is divided into a plurality of pieces, better attenuation characteristics can be obtained.

In this embodiment, each conductive wire 12-1,
As described above, the case where the cross section 12-2 has a circular cross section as shown in FIG. 1C is taken as an example.
When it is desired to form a large capacitance between -1, 12-2 or to obtain a large rated current capacity, a rectangular wire having a rectangular cross section is used as the conductive wire 12- as shown in FIG. It is preferably used as 1, 12-2.

Further, in the above embodiment, the LC filter is formed by spirally winding the two electric wire cords 10-1 and 10-2 arranged in parallel, but if necessary, three or more electric wire cords may be used. The LC filters may be arranged in parallel and wound into a coil to form an LC filter.

FIG. 9 shows an equivalent circuit diagram of the LC filter thus formed. In this embodiment, 3
2 of the electric wire cords 10-1, 10-2, 10-3 of the book
I / O terminals 14a, 14b, 14e, 14f are connected to both ends of the electric wire cords 10-1, 10-3, respectively, and these are formed as current-carrying conductors.
The ground terminal 14c is connected to one end side of -2, and this is formed as a ground conductor. This also makes it possible to obtain an LC filter having good attenuation characteristics.

Second Embodiment FIG. 2 shows a second preferred embodiment of the LC filter according to the present invention. As shown in FIG. 2 (A), Example LC
The filter is formed by winding two electric wire cords 10-1 and 10-2 into a twisted coil.
With this configuration, the two electric wire cords 1
0-1 and 10-2 are integrated, a capacitance is formed between them in a distributed constant manner, and a floating capacitance is also formed on each wire cord 10-1 and 10-2. Moreover, since the electric wire cords 10-1 and 10-2 are formed in a twisted winding shape, they also function as a coil. Therefore, similarly to the first embodiment, it can function as a noise filter composed of L and C.

In the present embodiment, in addition to this, FIG.
Two twisted and wound electric wire cords 10-1 and 10 shown in
2 is wound in the shape of a spiral coil as shown in FIG. 2B and is integrally formed with an adhesive or the like so as not to lose its shape. By doing so, the LC filter of the embodiment can obtain larger L and C, and functions as a filter having a good attenuation curve.

Third Embodiment FIG. 3 shows a preferred third embodiment of the present invention.
As shown in FIG. 3A, in the LC filter of the embodiment, a longer electric wire cord 10-1 and a shorter electric wire cord 10-2 are arranged in parallel. And long wire cord 10-1
A notch 11 is provided at a predetermined position in the middle of the
-Expose part of -1. Further, in the vicinity of the cutout portion 11, the conductive wire 12 of the lower electric wire cord 10-2 is pulled out from the insulator 13.

The parallel electric wire cord 10 thus formed
-1, 10-2 are wound and formed in a spiral coil shape as shown in FIG. 3 (B) to form an LC filter.

FIG. 9B shows an equivalent circuit thereof. One input / output terminal 14a is taken out from the cutout portion 11 from the first conductive wire 12-1, and the other input / output terminal 14b is provided from the other end portion where the second electric wire cord 10-2 is not adjacent. It has been taken out. A ground terminal 14c is taken out from the second conductive wire 12-2 for grounding at a position close to the input / output terminal 14a in terms of circuit arrangement.
By doing so, the discarded winding coil portion (the coil portion that does not carry a signal) 12 of the first conductive wire 12-1
-1a is magnetically coupled to the grounding conductive line 12-2, and both of the conductive lines 12-1a and 12-2 are magnetically coupled to the conductive line 12-1b functioning as an energization region. Moreover, a capacitance is formed in a distributed constant manner between the conductive lines 12-1a and 12-2 facing each other, and each conductive line 1
Floating capacitors are also formed around 2-1a, 12-1b, and 12-2.

Therefore, the LC filter of the embodiment has good attenuation characteristics in which the conductive lines 12-1a, 12-1b and 12-2 are magnetically coupled to each other and L and C act effectively. It will function as a LC filter having.

FIG. 4 shows an example in which leads 20a, 20b, 20c functioning as input / output terminals 14a, 14b and a ground terminal 14c are attached and fixed to the LC filter shown in FIG. Each of these leads 20a,
It is preferable that the 20c and 20b are formed at equal intervals and located on the same plane, and by doing so, it is possible to easily install them at predetermined positions on the PC board.

FIG. 5 shows the LC filter 100 shown in FIG.
An example of forming an SMD type element by using is shown.

This SMD type element includes the LC filter 100 according to the first embodiment and an insulating mounting portion 110 to which the LC filter 100 is mounted and fixed.

The mounting portion 110 is formed of an insulating resin into a rectangular thick plate shape, and terminals 14a, 14b, 14c and 14d are provided at four corners thereof. These terminals 14a, 14b, 14c, 14d are attached to the mounting portion 1
It is formed by coating a conductive material from the front surface side of 10 to the PC board mounting surface side of the back surface. Then, each conductive wire 12-1, 1 of the LC filter 100 is
2-2 are connected to the corresponding terminals 14a, 14b, 14
It is formed by connecting and fixing to c and 14d.

With the above structure, the element of the embodiment functions as a 4-terminal LC filter regardless of whether the element is attached to the PC board in the right direction or the left direction. It is possible to reduce the mounting mistake of.

Further, by grounding only one of the terminals 14c and 14d and leaving the other in an open state,
It can also be used as the 3-terminal LC filter shown in FIG. As described above, the LC filter shown in FIG. 5 can be used as a 4-terminal LC filter or a 3-terminal LC filter depending on the situation of the PC board on which the mounting portion 110 is mounted and fixed. ..

FIG. 6 shows another example of the present invention.

The LC element of the embodiment is an electronic component formed by winding the LC filter 100 as shown in FIG. 1 around the bobbin 120. Then, the LC filter 10
Each of the ends of the conductive wires 12-1 and 12-2 of 0 has four terminals 14a, 14b, which are provided on the insulating bobbin 120.
14c and 14d, respectively. Here, each of the terminals 14 is mounted on the bobbin 12 having an insulating property.
It is formed by using a conductive material from the upper surface of 0 to the PC board mounting surface installation surface.

By doing so, the LC filter also functions as an LC filter having a good attenuation characteristic as in the above-mentioned embodiment.

In particular, in the LC filter of the type using the bobbin 120 as in the present embodiment, an LC filter having a larger inductance can be obtained by using the magnetic material in the portion which becomes the winding core of the bobbin 120.

FIG. 10 shows an example of a manufacturing process of a 3-terminal LC filter using a lead frame.

First, as shown in FIG. 10A, in the lead frame 200 used in the embodiment, the three leads 20a, 20c, 20b arranged in parallel form a set of units 210, and a plurality of units 210 are provided. Both ends of are connected and fixed by connecting members 212 and 214. The lead frame 200 thus formed is first attached to each unit 2
The connecting members 212 and 214 are cut and removed so as to be separated for each 10.

Next, as shown in FIG. 10B, with respect to each of the leads 20a and 20c of the cut unit 210,
Conductive wires 12-1, 12 of electric wire cords 10-1, 10-2
-One end side of -2 is bonded and fixed by soldering or welding.

Next, as shown in FIG. 10 (C), the lead wires 20a, 20c, 20b are wound around the leads 20a, 20c, 20b as cores while being kept parallel to each other, and then fixed. The other end of the conductive wire 12-1 is connected to the lead 20b.
It is fixed by attaching to, for example, by welding or soldering.

Next, as shown in FIG. 10 (D), the connecting material 214 located on the upper side is cut and removed, and then, FIG. 11 (E).
The surface of the winding is coated with epoxy resin, etc.

Thereafter, the remaining connecting material 212 is cut and removed from the unit 210 as shown in FIG.
An LC filter having the equivalent circuit shown in FIG.

By doing so, it becomes possible to manufacture an LC filter having always stable quality.

The present invention is not limited to the above embodiments, and various modifications can be made within the scope of the present invention.

For example, in the above embodiment, the conductive wire 12
As described as an example of using a wire rod having a circular cross section or a rectangular wire having a rectangular cross section, the present invention is not limited to this.
For example, as shown in FIG. 11A, electric wire cords 10-1, 1
As 0-2, a thin plate-shaped conductive wire 12-1.12-2 whose surface is covered with an insulating material 13 may be used.

Then, as shown in FIG. 11B, the thin plate-shaped electric wire cords 10-1 and 10-2 are arranged in parallel.
Is spirally wound to form a coil. Then, similarly to the above-described embodiment, the LC filter can be formed by connecting terminals (not shown) to both ends or one end of each of the conductive lines 12-1 and 12-2.

In particular, by forming in this way, the facing area of the thin plate-shaped conductive lines 12-1 and 12-2 becomes large, so that an LC filter having a large capacitance C can be obtained. Further, the facing area can be further increased by providing unevenness such as jaggedness on the surfaces of the conductive wires 12-1 and 12-2.

The capacitance can also be increased by increasing the dielectric constant of the insulator 13 of the wire cord 10.

Further, in each of the above-mentioned embodiments, in order to increase the inductance of the LC filter, a part or all of the conductive wire 12 may be formed by using a magnetic conductive material (for example, iron).

If necessary, the LC filter 100 of each of the embodiments can be provided with a core made of a magnetic material to increase its inductance.

In the above-mentioned embodiment, the wire cord 10 is described as an example in which the surface of the conductive wire 12-1 is coated with the insulator 13, but the present invention is not limited to this. When the two conductive wires 12-1 and 12-2 are arranged in parallel and wound, either one of the conductive wires 1
It suffices to coat the insulating material only on the surface of 2-1.

Experimental Data FIGS. 12 to 14 show experimental data of the LC filter according to the present invention.

In the experiment, the air-core type LC filter of the first embodiment shown in FIG. 1 was used.

First, in FIG. 12, the inductance of the first conductive line 12-1 is L = 0,56 μH, and the resistance is R = 435 m.
Ω, the filter 10 having a capacitance C = 49.2 pF between the first conductive line 12-1 and the second conductive line 12-2.
It is the experimental data obtained with 0 as the measurement target.

FIG. 13 shows L = 0.15 μH and R = 318 m.
The data is obtained by using the filter 100 of Ω and C = 27.0 pF as a measurement target, and FIG. 14 shows L = 0.13 μ.
Filter 10 with H, R = 111 mΩ and C = 12.2 pF
This is data obtained by setting 0 as a measurement target.

As is clear from all the measured data, it was confirmed that the LC filter of this example exhibits excellent die attenuation characteristics over a wide band.

[0068]

As described above, according to the present invention,
By winding a plurality of conductive wires arranged in close proximity so as to be insulated from each other in a coil shape and using at least two of the plurality of conductive wires as current-carrying conductors, a good attenuation characteristic consisting of L and C is obtained, Moreover, it is possible to obtain a low cost LC filter having a simple structure.

Further, according to the present invention, any one of the plurality of conductive wires is used as the current-carrying conductor, and at least one of the other conductive wires is used.
By using one as a grounding conductor, it is possible to obtain a grounding type LC filter having a good attenuation, a simple structure, and a low cost.

Further, by using flat conductor wires as the plurality of conductive wires, an LC filter having a large capacitance can be obtained.

Further, by providing a plurality of conductive wires wound in a coil shape on the mounting portion in which the PC board mounting surface is formed in line symmetry, a mounting error of the LC filter attached to the PC board can be significantly reduced. It can be reduced.

[Brief description of drawings]

FIG. 1 is an explanatory view of a preferred first embodiment of an LC filter according to this embodiment, FIG. 1 (A) is an illustration of a parallel wire cord used in the LC filter of the embodiment, and FIG. 1 (B). Is an explanatory view of an LC filter formed by winding the parallel electric wire cord in a spiral shape, FIG. 3C is a schematic cross-sectional explanatory view of the electric wire cord shown in FIG. 3A, and FIG. It is a cross-sectional explanatory drawing of the modification which uses a rectangular conducting wire as an electric wire code shown in FIG.

FIG. 2 is an explanatory view of a second preferred embodiment of the LC filter of the present invention, and FIG. 2 (A) is an explanatory view showing a state in which a plurality of electric wires are twisted together and arranged adjacent to each other; ) Is a schematic explanatory view of an LC filter formed by spirally winding the electric wire shown in FIG. 7A, and FIG.
It is a cross-sectional schematic explanatory drawing of the electric wire cord shown in FIG.

FIG. 3 is an explanatory view of a preferred third embodiment of the LC filter of the present embodiment, FIG. 3A is an explanatory view of an electric wire cord used in the embodiment, and FIG. 3B is an explanatory view of the electric wire cord. It is explanatory drawing of the LC filter formed by winding in a spiral shape.

FIG. 4 is a schematic explanatory view of a three-terminal type LC filter formed by connecting leads as terminals to the LC filter shown in FIG.

5 is an explanatory diagram of a case where the LC filter shown in FIG. 1 is used by being fixedly mounted on a PC board mounting portion.

FIG. 6 is a schematic explanatory diagram of the case where the LC filter shown in FIG. 1 is wound around a bobbin to be formed.

FIG. 7 is an equivalent circuit diagram of each embodiment of the LC filter of the present embodiment. FIG. 7A is an equivalent circuit diagram when the LC filter shown in FIG. 1 is used as a 4-terminal type filter. (B) is an equivalent circuit diagram when it is used as a three-terminal LC filter, and (C) and (D) are explanatory diagrams of an equivalent circuit when the ground conductor is divided into a plurality of parts.

FIG. 8 is an explanatory diagram of the case where the position of the ground terminal with respect to the input / output terminal of the three-terminal LC filter is changed. FIG. FIG. 2B is a schematic explanatory diagram when it is provided at a position, and FIG. 6B is an explanatory diagram when the ground terminal is moved with reference to the one input / output terminal.

FIG. 9 is an equivalent circuit diagram of another embodiment of the present invention, where FIG. 9A is an equivalent circuit diagram of an LC filter when three conductive wires are used, and FIG. FIG. 4 is an equivalent circuit diagram of an LC filter formed by facing a winding conductor to a ground conductor.

FIG. 10 is an explanatory diagram showing a series of manufacturing steps in the case where the LC filter of the example is formed using a lead frame.

FIG. 11 is an explanatory diagram of a case where the LC filter of the example is formed by using thin plate-shaped conductive wires, and FIG. 11A is a description of a state in which two current-carrying conductors arranged in parallel are developed. Figure,
FIG. 2B is an explanatory diagram of a case where the spirally wound member is formed.

FIG. 12 shows the LC filter shown in FIG.
It is explanatory drawing of the attenuation characteristic data when using it as a terminal normal mode type LC filter.

FIG. 13 is an explanatory diagram of attenuation characteristic data measured under different experimental conditions from FIG. 12.

FIG. 14 is an explanatory diagram of attenuation characteristic data measured under different experimental conditions from FIGS. 12 and 13.

[Explanation of symbols]

 10 Wire Cord 12 Conductive Wire 13 Insulator 14 Terminal 20 Lead 100 LC Filter 110 Mounting Plate 120 Bobbin 200 Lead Frame

Claims (7)

[Claims] 1. A plurality of conductive wires, which are arranged adjacent to each other so as to be insulated from each other, are wound in a coil shape, and at least two of the plurality of conductive wires are formed as current-carrying conductors. LC filter to do. 2. A plurality of conductive wires, which are arranged adjacent to each other so as to be insulated from each other, are wound in a coil shape, and at least one of the plurality of conductive wires is formed as a current-carrying conductor. An LC filter, wherein at least one of the wires is formed as a ground conductor. 3. The LC filter according to claim 1, wherein the plurality of conductive wires are wound in a spiral coil shape. 4. The LC filter according to claim 1, wherein the plurality of conductive wires are wound into a twisted coil shape. 5. The LC filter according to claim 1, wherein the plurality of conductive wires are twisted and wound into a spiral coil. 6. The LC filter according to claim 1, wherein a flat conductor wire is used as the conductive wire. 7. The mounting body according to claim 1, wherein the plurality of conductors wound in the coil shape are mounted and fixed, and a PC board mounting surface thereof is formed in a line-symmetrical shape. , A plurality of terminal portions connected to the plurality of conductors are arranged line-symmetrically on the PC board mounting surface of the mounting portion, and the mounting portion can be bidirectionally mounted and fixed to the PC board. LC filter characterized by.