JP2769346B2 - Cylindrical LC noise filter and method of manufacturing the same - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a completely novel LC noise filter using an insulating cylinder and a method of manufacturing the same.

[Background Art] With the development of electronic technology in recent years, electronic circuits have been widely used in various fields, and it is desired to operate each of these electronic circuits stably and reliably without being affected by outside.

However, since noise enters the electronic circuit directly or indirectly from the outside, malfunctions are often caused in various electronic devices using the electronic circuit.

In order to remove such noise, various noise filters are generally used in electronic circuits. In particular, in recent years, many types of high-performance electronic devices have been used, and regulations on noise have become increasingly strict. For this reason, a compact and high-performance noise filter that can reliably remove generated noise has been developed. Is desired.

[Problems to be Solved by the Invention] The present invention has been made in view of such conventional problems, and an object of the present invention is to provide an LC noise adopting a completely novel structure using an insulating cylinder. To provide a filter.

[Means for Solving the Problems by the Invention] In order to achieve the above object, the present invention provides an insulating cylinder, and a spirally provided inner or outer peripheral surface of the cylinder to function as an inductor. A first conductor, and an outer circumferential surface or an inner circumferential surface of the cylindrical body,
And a second conductor that is provided to face the first conductor and forms a capacitor with the first conductor.

In addition, the method of the present invention includes dipping an insulative cylinder having a spiral groove formed on an inner peripheral surface thereof and a resist applied thereon to form a conductor pattern having a predetermined shape on an outer peripheral surface, in a conductive tank. Thereafter, the conductive layer coated on the inner peripheral surface of the cylindrical body is polished and removed using a polishing member to form a spiral-shaped first conductor on the inner peripheral surface, and the first conductor is formed on the outer peripheral surface through the cylindrical body. A second conductor is formed so as to face the first conductor.

[Operation] Next, the operation of the present invention will be described.

In the noise filter of the present invention, the second conductor and the first conductor formed in a spiral shape are arranged to face each other via an insulating cylinder.

The first conductor is used as a signal line or a power supply line, and functions as an inductor by being formed in a spiral shape. The second conductor forms a capacitor between the second conductor and the first conductor.

Therefore, the filter of the present invention has L
And C as an LC noise filter.

In particular, according to the present invention, it is preferable that a first conductor used for a signal line or a power supply line is provided on an inner periphery of a cylinder, and the second conductor is provided on an outer periphery of the cylinder. Accordingly, the noise radiated from the signal line or the power supply line is absorbed by the second conductor provided around the signal line or the power supply line, and the noise radiated from the line to the surroundings can be reduced.

Further, according to the noise filter manufacturing method of the present invention, the insulating cylinder in which the spiral groove is formed in advance and the periphery of which is coated with the second conductor forming resist is placed in the conductive tank. Dipping in. Thereafter, the cylindrical body is pulled up from the conductive tank, and the conductive material attached to the inner peripheral surface of the cylindrical body is removed using a polishing means. As a result, only the conductive material attached to the spiral groove remains on the inner peripheral surface of the cylindrical body, and this functions as the first conductor.

Further, since the outer peripheral surface of the cylindrical body is coated with a resist so as to cover the second conductor having a predetermined shape, the outer peripheral surface of the cylindrical body is merely dipped in a conductive bath. Is formed by coating.

Thus, according to the method of the present invention, the L and C noise filters can be easily formed using the insulating cylinder.

Next, a preferred embodiment of the present invention will be described with reference to the drawings.

First Embodiment FIG. 1 shows a preferred first embodiment of the LC noise filter according to the present invention.

In the case of manufacturing the noise filter of the embodiment, as shown in FIG. 2 (A), a spiral groove 12 having a predetermined pitch is formed in advance on the inner peripheral surface of a cylindrical ceramic body 10 having a cylindrical shape. deep. In an embodiment, the spiral groove 12
Are formed at a constant pitch, and both ends thereof are extended to both ends of the cylindrical body.

Further, on the outer peripheral surface of the cylindrical body 10, resists 14a and 14b are applied in a ring shape in the vicinity of the openings at both ends thereof, so that the conductor is not attached to this portion.

Then, as shown in FIG. 2 (B), the cylindrical body 10 is dipped in a conductive tank 16 filled with a liquid conductive material, and the conductive material is attached to the surface thereof.

Thereafter, as shown in FIG. 2C, when the cylindrical body 10 is pulled up from the conductive tank 16, the conductive material is entirely covered except for the region where the resist 14 is applied. At this time, the conductive material adhered to the surface of the cylindrical body 10 is electrically separated by the resists 14a and 14b.
One conductive layer 100 is formed by coating from the inner surface of the cylindrical body 10 to both ends thereof, and the other conductive layer 200
Is formed to cover the outer peripheral surface of the cylindrical body 10 in a cylindrical shape.

Then, after the conductive layers 100 and 200 are dried, the conductive layer 100 attached to the inner peripheral surface 10a of the cylindrical body 10 is removed using the surface polishing member 20 as shown in FIG. In the embodiment, the surface polishing member 20 is formed in a substantially cylindrical shape in accordance with the inner diameter of the cylindrical body 10, and a surface polishing agent is provided on an outer peripheral surface thereof. Then, the surface abrasive 20 is rotated while being inserted into the inner peripheral surface of the cylindrical body 10, and the conductive layer 1 adhered to the inner peripheral surface 10a is rotated.
00 is entirely removed except for the conductive layer adhered in the spiral groove 12.

By doing so, as shown in FIG.
A first conductor 30 is formed on the inner peripheral surface 10a of the cylindrical body 10 along the spiral groove 12, and both ends of the first conductor 30 are cylindrical bodies.
It will be electrically connected to the conductive layers 100a and 100b provided in the openings at both ends of 10. And each of these conductive layers 100
Input and output leads 34a and 34b are connected to a and 100b.

FIG. 1B schematically shows the first conductor 30 spirally provided on the inner peripheral surface of the cylindrical body 10 in this manner.

Further, a conductive layer 200 formed on the outer peripheral surface of the cylindrical body 10 by coating.
Is used as the second conductor 40. And this second
The conductor 40 is disposed to face the first conductor 30 with the cylindrical body 10 interposed therebetween, and forms a capacitor between the two. In the embodiment, the second conductor 40 is used as a ground conductor to which a ground lead 42 is connected.

Accordingly, in the noise filter of the present embodiment, the first conductor 30 provided in a spiral shape functions as an inductor, and the second conductor 40 provided so as to face the first conductor 30 functions as a capacitor. It operates as a normal mode noise filter composed of L and C shown in the figure.

Accordingly, by connecting the first conductor 30 to a signal line or a power supply line, noise can be removed from a signal or a power supply current flowing through these lines.

In particular, according to the present embodiment, the second conductor 40 is disposed so as to face the first conductor 30 wound in a spiral shape, and a capacitor is formed between them in a distributed constant manner. For this reason, the noise component can be effectively removed from the signal or power supply current propagating in the first conductor 30 as compared with the lumped constant type LC noise filter.

Further, according to the present embodiment, the first conductor 30 connected to the signal line or the power supply line is provided inside the cylinder 10, and the second conductor 40 used as the ground conductor is
It is provided outside the cylinder 10. Therefore, the first conductor
When a signal or power supply current flows through 30, this first conductor
The noise radiated from 30 to the surroundings is absorbed by the second conductor 40, and the noise radiated to the outside can be greatly reduced.

Further, by providing a cut or a streak in the second conductor 40, for example, eddy current flowing through the second conductor 40 can be reduced, and noise can be more effectively removed.

Further, the noise filter of the present embodiment can be formed as a distributed constant circuit in which L and C are unevenly distributed as shown in FIG. By doing so, depending on the type of signal, it is possible to more effectively remove only noise components without causing distortion in the signal.

A noise filter having such a non-uniform distributed constant circuit can be formed by changing the pitch intervals l ₁ and l ₂ of the first conductor 30 formed in a spiral shape, for example, as shown in FIG. Alternatively, as shown in FIG. 6, it can be formed by sequentially changing the diameter 2R of the inner peripheral surface 10a of the cylindrical body 10.

In the embodiment, both ends of the first conductor 30 are connected to the conductive layers 100a, 100a provided near the both ends of the cylindrical body 10.
00b, and the input / output leads 34 from the conductive layers 100a and 100b.
Although the case where the a and 34b are taken out has been described as an example, the present invention is not limited to this. In addition, for example, at both ends of the first conductor 30 formed in a spiral shape as shown in FIG. 7 to FIG. It may be formed so as to directly connect the input / output leads 34a and 34b.

Second Embodiment By the way, in the first embodiment, the second conductor is formed in a cylindrical shape so as to cover the outside of the first conductor 30 formed in a spiral shape. For example, when a signal current is applied, an eddy current may be generated in the second conductor 40, and the expected inductance of the first conductor 30 may not be obtained.

That is, in such an LC noise filter,
A second conductor 40 as a ground conductor is capacitively coupled to the spiral first conductor 30 by electrostatic capacitance and inductively coupled. Accordingly, a magnetic flux generated by the current flowing through the spiral first conductor 30 generates an electromotive force also on the second conductor 40, and the electromotive force generates an eddy current on the second conductor 40.

If the spiral first conductor 30 is compared to the primary coil of a transformer, the second conductor 40 as a ground conductor acts like a short-circuited secondary coil, and the spiral first conductor
The expected inductance L cannot be obtained in the conductor 30 and there is a possibility that a sufficient function as an LC noise filter cannot always be exhibited.

In order to solve such a problem, it is conceivable that the second conductor 40 as the ground conductor has a structure in which streaks or cuts are formed and eddy current hardly flows. However, even in this case, although the value is reduced, the eddy current flows through the second conductor 40.

In view of such a fact, the present inventor has proposed how to form the second conductor 40 with respect to the first conductor 30 formed in a spiral shape and functioning as an inductor. We investigated whether an LC noise filter with good characteristics could be obtained without deteriorating the function as a filter.

The inventor can reduce the inductance of the first conductor 30 by forming the second conductor 40 so as not to obstruct the magnetic path of the magnetic flux generated when the spiral first conductor 30 is energized. It has been found that an LC noise filter having good electric characteristics can be obtained without lowering.

FIGS. 10 to 13 show a preferred embodiment of the present invention made from such a viewpoint.

The noise filter of the embodiment has an inner peripheral surface 10a of the cylindrical body 10,
Similar to the first embodiment, the first
Is formed in a spiral shape.

Further, in the noise filter of the embodiment, as shown in FIG. 10, a second conductor 40 is formed in a spiral shape on the outer peripheral surface 10b of the cylindrical body 10 so as to face the first conductor 30, The second conductor 40 and the second conductor 40 are capacitively coupled by capacitance, and a capacitor is formed therebetween.

Then, input / output leads 34 are provided at both ends of each of these conductors 30, 40.
a, 34b, 42a, 42b are connected.

In this case, as shown in FIG. 11, for example, the second conductor 40 is coated with a resist so that the conductor is coated on the outer peripheral surface 10b of the cylindrical body 10 in a spiral shape, and then the cylindrical body 10 is placed in the conductive layer. It may be formed by dipping. In addition, as shown in FIG. 12, for example, as shown in FIG. 12, a spiral groove 44 is formed in advance on the outer periphery of the cylindrical body 10, and after this cylindrical body 10 is dipped in a conductive tank, the conductive The conductor 40 may be formed by polishing the outer peripheral surface so as to leave only the layer.

FIG. 13 is an equivalent circuit diagram of the LC noise filter of the present embodiment, and the first conductor 30 formed in a spiral shape in the present embodiment functions as a first inductor L1. Further, the first conductor 30 and the second conductor 40 are cylindrical bodies.
Since they are spirally formed so as to be opposed to each other with 10 interposed therebetween, they are capacitively coupled to each other by capacitance, and a capacitor C is formed between them as a distributed constant.

Further, since the second conductor is formed in a spiral shape, the second conductor 40 also functions as the second inductor L2.

Therefore, the noise filter of this embodiment functions as a distributed constant type LC noise filter having a circuit configuration as shown in FIG.

In particular, in the noise filter of the present invention, the second conductor 40 forming a capacitor with the first conductor 30 is formed so as not to obstruct the magnetic path of the first conductor 30.

That is, the magnetic flux generated when the first conductor 30 is energized passes between the lines of the first conductor 30 from the back side to the front side of the cylindrical body 10 or in the opposite direction. At this time, if the second conductor 40 is provided so as to obstruct the magnetic path (for example, the second conductor 40 is opposed to the line region of the first conductor 30).
If the first conductor 30 is provided), the magnetic path may be blocked by the second conductor 40, and the first conductor 30 may not function sufficiently as an inductor.

On the other hand, by providing the second conductor 40 in a spiral shape so as to face the spiral first conductor 30 as in the present invention, the magnetic path of the first conductor 30 is
Is not hindered by anything. Therefore, the effect of the LC noise filter can be sufficiently exhibited without reducing the inductance of the spiral first conductor 30.

Therefore, for example, the input / output leads 42a, 42b of the second conductor 40
At least one of the first conductor 30
If the input / output leads 34a and 34b are connected to the input / output terminals, respectively, the noise filter of the present embodiment can be used as a normal mode noise filter having good electrical characteristics.

Further, each input / output lead 34 of the first and second conductors 30 and 40 is provided.
If a, 34b, 42a, 42b are used as input / output terminals, respectively,
The noise filter of this embodiment can be used as a four-terminal type common mode noise filter having good electric characteristics.

Third Embodiment FIG. 14 shows a third preferred embodiment of the present invention.

As shown in FIG. 14 (B), the LC noise filter of the embodiment has two sets of inductor conductors 30a, 3a on the inner peripheral surface 10a of the cylindrical body 10.
0b as a first conductor in a spiral shape.
As shown in FIG. 14A, two sets of capacitor conductors 40a and 40b opposed to the inductor conductors 30a and 30b are formed in a spiral shape on the outer peripheral surface 10b of the cylindrical body 10 as second conductors. A common mode LC noise filter as shown in FIG. 13 is formed.

That is, the noise filter of the embodiment is shown in FIG.
As shown in FIG. 5, a first inductor conductor 30a and a second inductor conductor 30b are formed in a spiral shape on the inner peripheral surface 10a of the cylindrical body 10 so as to be adjacent to each other. And each inductor conductor
Outer ends of 30a, 30b are connected to conductive layers 100a, 110a, 100b, 110b provided at both ends of the cylindrical body 10.

And, in each of these conductive layers 100a, 110a, 100b, 110b,
Input / output leads 34a, 36a, 34b, 36b are connected.

Further, as shown in FIG.
In b, a capacitor conductor 40a is formed spirally so as to face the inductor conductor 30a, and similarly, the capacitor conductor 40b is formed spirally so as to face the inductor conductor 30b. One end of each of these capacitor conductors 40a and 40b is electrically connected to each other,
Connected to ground lead 42a.

FIG. 15 shows an equivalent circuit diagram of the LC noise filter of the present embodiment. In the present embodiment, the inductor conductor 30a formed in a spiral shape functions as the first inductor L1, and likewise has a spiral shape. The inductor conductor 30b formed as described above functions as a second inductor L2.

The two sets of capacitor conductors 40a, 40b provided on the outer peripheral surface 10b of the cylindrical body 10 may obstruct the magnetic path between the inductor conductors 30a, 30b opposed to each other across the cylindrical body 10. The capacitor is formed with a distributed constant so as not to cause the problem.

Therefore, the noise filter according to the present embodiment does not reduce the inductance of each of the inductor conductors 30a and 30b,
The function and effect of the common mode type LC noise filter can be sufficiently exhibited.

Fourth Embodiment By the way, when the signal current or the power supply current is applied to the first conductor 30 functioning as an inductance and the frequency of the applied current increases, the first to third embodiments are wound in a spiral shape. A short circuit occurs between the first conductors 30 and the first conductor 30 does not function sufficiently as an inductance.

In particular, such a line-to-line short-circuit phenomenon occurs more frequently as the frequency of the energized signal becomes higher, and thus a countermeasure is required.

FIG. 16 shows a preferred embodiment of the present invention in which such a problem is solved.

The feature of this embodiment is that the shield conductor 60 is formed in a spiral shape between the lines of the first conductor 30 formed on the inner peripheral surface 10a of the cylindrical body 10 as shown in FIG. 16 (B). It is in.

One end of the shield conductor 60 is a cylindrical body.
It is electrically connected to the conductive layer 100c formed on the end face of the ten.

Further, in the noise filter of this embodiment, as shown in FIG. 16 (A), a shield conductor 70 is formed in a spiral shape on the outer peripheral surface of the cylindrical body 10 between the lines of the second conductor 40. One end of the shield conductor 70 is similarly connected to the conductive layer 100c. The conductive layer 100c is connected to the ground lead 72.

With the above configuration, in the noise filter of the present embodiment, the line between the first and second conductors 30 and 40 is shielded by the shield conductors 60 and 70, and the occurrence of a short circuit between the lines is reduced. Since it is prevented, it functions as a noise filter having excellent electric characteristics from a low frequency band to a high frequency band.

In particular, in the present embodiment, not only the first conductor 30 but also the second conductor 40 is prevented from being short-circuited by the shield conductor, so that the second conductor 40 is suitable for use as a common mode noise filter. Become.

When the noise filter of the present embodiment is used as a normal mode noise filter, the first conductor
It is sufficient to provide the shield conductor 60 for preventing the line-to-line short-circuit of the 30, and the shield conductor 70 for preventing the line-to-line short-circuit of the second conductor 40 may be omitted.

Fifth Embodiment FIG. 17 shows a fifth preferred embodiment of the present invention.

The feature of this embodiment is that the noise filter shown in FIG. 14 is provided between inductor conductors 30a and 30b in FIG.
The first shield conductor 60a is formed as shown in FIG.
Similarly, a second shield conductor 60b is formed spirally between the inductor conductors 30b and 30a,
Shielding between a and 30b.

One end of each of the conductors 60a and 60b is connected to the ground lead 72 via a conductive layer 100c provided on the opposite end surface of the cylindrical body 30.

By doing so, according to the present embodiment, it is possible to obtain a common mode noise filter having excellent electrical characteristics from a low frequency to a high frequency band.

Sixth Embodiment In the LC noise filter according to the present invention, the first
In addition to the number of turns and arrangement of the conductor 30 and the second conductor 40,
By appropriately selecting the material of the cylinder 10, the inductance L and the capacitance C of the noise filter can be arbitrarily set.

For example, when a large inductance L is required, the cylindrical body 10 may be formed using a magnetic material or the like, or may be dipped in magnetic powder. If it is desired to increase the capacitance C, the cylinder 10 may be formed using a material having a high dielectric constant such as ceramics. In order to increase both L and C, the cylinder 10 may be formed using both a material having a high dielectric constant and a magnetic material.

In addition, when it is desired to increase the inductance L, for example, the hollow portion of the cylindrical body 10 may be filled with a magnetic material. In this way, a noise filter having a large L component can be formed.

FIGS. 18 and 19 show a preferred embodiment of the present invention from such a viewpoint. In the noise filter of the embodiment, a screw groove 80 is formed in a spiral shape on the inner peripheral surface 10a of the cylindrical body 10, and the first groove is formed at the bottom of the screw groove 80.
Of the conductor 30 is formed. Thereby, the first conductor
30 is formed in a spiral shape as in the above-described embodiments.

Although not shown, a second conductor 40 is formed in a spiral shape on the outer peripheral surface of the cylindrical body 10 so as to face the first conductor 30.

A screw 90 is formed in the cylindrical body 10 so as to be screwed while the screw thread 92 is screwed with the screw groove 80. In this case, the thread 92 has a thread groove 80
The top is formed flat so that it does not contact the first conductor 30 formed on the bottom when screwed.

The feature of this embodiment is that the screw 90 is formed using a magnetic material.

Thus, by adjusting the depth at which the screw 90 is screwed into the cylinder 10, the inductances L1 and L2 of the first conductor 30 and the second conductor 40 can be adjusted to arbitrary values, and the inductance adjustment can be performed. Is very suitable as a required LC noise filter.

Other Embodiments 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, the second to fifth embodiments can be formed as a noise filter having a circuit having a non-uniform distribution constant as in the first embodiment.

In this case, for example, the pitch interval of the first conductor 30 formed in a spiral shape may be changed as shown in FIG. 5, or as shown in FIG. surface
The diameter 2R of 10a may be changed.

Also in the second to fifth embodiments, the first conductor
Both ends of 30 may be formed so as to be directly connected to input / output leads 34a and 34b as shown in FIGS. 7 to 9 without using a conductive layer.

In each of the above embodiments, the first conductor
The case in which 30 is formed on the inner peripheral surface 10a of the cylindrical body 10 has been described as an example. However, the present invention is not limited to this.
Is formed on the outer peripheral surface 10b of the cylindrical body 10, and the second conductor 40
May be formed on the inner peripheral surface of the cylindrical body 10.

Further, in each of the above embodiments, the case where each of the conductors 30 and 40 is formed by dipping the cylindrical body 10 in the conductive tank is described as an example, but the present invention is not limited to this, and for example, the first embodiment
The conductor 30 may be a conductive wire wound in advance in a spiral shape, and the conductor 40 may be a conductive plate or a conductive wire formed in a cylindrical or spiral shape.

Further, the LC noise filter of the present invention can be used both as a high-frequency noise filter for a signal line and as a low-frequency noise filter for a power supply line. When used as a high-frequency noise filter, it is preferable to set the values of L and C to small values. When used as a low-frequency noise filter for a power supply line, L
It is preferable to set the values of C and C large.

In particular, when the noise filter of the present invention is used as a high-frequency filter, since L and C function as a noise filter having a distribution constant, the noise component can be favorably used without distorting the waveform of the original signal. There is an excellent effect that it can be removed.

Further, in the present embodiment, by forming the cylindrical body 10 using a material such as a high-frequency absorption heating element, noise generated from a signal passing through the conductor 30, particularly high-frequency noise is absorbed as heat, and Effective noise removal can be performed.

Further, in the present embodiment, the case where the cylindrical body 10 is formed in a cylindrical shape has been described as an example, but other than this, cylindrical bodies of various shapes may be used as needed.

For example, the filter of the present invention can be formed as an SMD type electronic component by forming the cylindrical body 10 into a rectangular cylindrical body as shown in FIG.

Further, by connecting the filter of the present invention to each channel of a multi-channel plug or a multi-channel socket (not shown) shown in FIG. 21, a multi-channel noise filter can be easily formed.

For example, taking a multichannel plug shown in FIG. 21 as an example, the filter F _1, F ₂ ... F ₅ of the present invention connected to the pins P _1, P ₂ ... P ₅ multichannel, inside the plug With this arrangement, a multi-channel noise filter can be configured.

[Effects of the Invention] As described above, according to the present invention, a novel configuration is adopted in which a first conductor and a second conductor formed in a spiral shape are opposed to each other via an insulating tubular body. By doing so, it is possible to provide a cylindrical noise filter capable of reliably removing various noises.

In particular, in the present invention, the second conductor is formed so as to face the first conductor so as not to obstruct the magnetic path of the magnetic flux generated when the first conductor formed in a spiral shape is energized. Thus, a cylindrical LC noise filter having excellent electrical characteristics can be obtained without reducing the inductance of the first conductor.

Furthermore, according to the present invention, by providing a shield conductor between the spiral first conductors to prevent this line-to-line short-circuit, noise components can be removed without causing a line-to-line short-circuit even in a high-frequency band. Thus, a cylindrical LC noise filter that can be manufactured can be obtained.

[Brief description of the drawings]

1 (A) and 1 (B) are explanatory diagrams showing an example of an LC noise filter according to the present invention. FIGS. FIG. 3 is an equivalent circuit diagram of the noise filter shown in FIG. 1, FIG. 4 is an equivalent circuit diagram of another embodiment of the noise filter of the present invention, and FIGS. 5 and 6 are equivalent diagrams shown in FIG. FIGS. 7 to 9 are explanatory diagrams showing other specific examples of the noise filter of the present invention, and FIGS. 10 to 12 are noise filters of the present invention. Preferred second
FIG. 13 is an equivalent circuit diagram of FIGS. 10 to 12, FIGS. 14 (A) and (B) are explanatory diagrams of a preferred third embodiment of the present invention, and FIG. FIG. 14 is an equivalent circuit diagram, FIGS. 16 (A) and (B) are explanatory diagrams of a preferred third embodiment of the present invention, and FIGS. 17 (A) and (B) are preferred fourth embodiments of the present invention. FIGS. 18 and 19 are explanatory diagrams of a preferred fifth embodiment of the present invention, FIG. 20 is an explanatory diagram of a filter of the present invention formed as an SMD type, FIG. FIG. 3 is an explanatory diagram of a multi-channel noise filter formed using the present invention. 10: cylindrical body, 12: spiral groove, 14: resist, 16: conductive tank, 30: first conductor, 30a, 30b: inductor conductor 40: second conductor, 40a, 40b: capacitor conductor, 60, 70 ... Sealed conductor, 80 ... thread groove, 90 ... screw, 92 ... thread.

Claims (11)

(57) [Claims] 1. An insulating cylinder, a first conductor spirally provided on one of an inner peripheral surface and an outer peripheral surface of the cylinder and functioning as an inductor, and a first conductor provided on the other surface of the cylinder. A second conductor provided so as to face the first conductor via a cylinder, and forming a capacitor with the first conductor, the second conductor being the other of the cylinders Are formed in a spiral shape so as not to obstruct the magnetic path of the first conductor. Both ends of the first and second conductors are respectively connected to input / output leads, and are formed as a common mode type. A cylindrical LC noise filter characterized by the following. 2. An insulative cylinder, a first conductor spirally provided on one of an inner peripheral surface and an outer peripheral surface of the cylinder and functioning as an inductor, and a second conductor on the other surface of the cylinder. A second conductor that is provided to face the first conductor via a cylinder, and forms a capacitor with the first conductor; and a first conductor on the one surface of the cylinder, A cylindrical LC noise filter, comprising: a shield conductor provided between conductor lines to prevent a short circuit between the first conductors. 3. An insulating tubular body, a first conductor spirally provided on one of an inner peripheral surface and an outer peripheral surface of the tubular body and functioning as an inductor, and a first conductor provided on the other surface of the tubular body. A second conductor that is provided on the inner peripheral surface to face the first conductor via a cylinder and forms a capacitor with the first conductor; and a thread groove formed on a hollow inner wall of the cylinder. And a magnetic material formed in a screw shape so as to be able to arbitrarily adjust the depth of entry into the cylindrical hollow portion by screwing with the screw groove, and the depth of entry of the screw type magnetic material into the cylindrical hollow portion. A cylindrical LC noise filter characterized by being formed so as to change the inductance and adjust the inductance to an arbitrary value. 4. An insulating tubular body, a first conductor spirally provided on one of an inner peripheral surface and an outer peripheral surface of the tubular body and functioning as an inductor, and a first conductor provided on the other surface of the tubular body. A second conductor provided to face the first conductor via a cylinder, and forming a capacitor between the first conductor and the first conductor, wherein the cylinder is formed using an electromagnetic wave absorbing heating element. A cylindrical LC noise filter characterized by: 5. The semiconductor device according to claim 2, wherein both ends of the first conductor are connected to input / output leads, respectively, and the second conductor is connected to a ground lead, and molded as a normal mode type. A cylindrical LC noise filter characterized by the following. 6. The cylindrical noise filter according to claim 5, wherein the second conductor is formed with cuts or streaks so as to reduce eddy currents. 7. The normal mode type according to claim 2, wherein both ends of said first conductor are respectively connected to input / output leads, and said second conductor is connected to a ground lead. A cylindrical LC noise filter characterized by being formed as: 8. The first conductor according to claim 1, wherein the first conductor includes at least two sets of inductor conductors formed on the one surface of the cylindrical body so as to be spiral when adjacent to each other, The second conductor is formed in a spiral shape on the other surface of the cylindrical body so as to face each of the inductor conductors, and includes at least two sets of capacitor conductors that form a capacitor between each of the inductor conductors. A cylindrical LC noise filter characterized in that each end of each set of the inductor conductors is connected to an input / output lead to form a common mode type. 9. The shield according to claim 1, wherein the shield is provided on the other surface of the cylindrical body between the wires of the second conductor, and prevents a short circuit between the wires of the second conductor. A cylindrical LC noise filter comprising a conductor. 10. The method according to claim 1, wherein the second conductor is provided on an outer periphery of the cylinder, and the first conductor is provided on an inner periphery of the cylinder. Cylindrical
LC noise filter. 11. An insulating cylindrical body having a spiral groove formed on an inner peripheral surface thereof and a register applied thereon to form a conductor pattern having a predetermined shape on an outer peripheral surface is dipped in a conductive tank. By polishing and removing the conductive layer coated on the inner peripheral surface of the body using a polishing member, a spiral-shaped first conductor is formed on the inner peripheral surface, and the first conductor is formed on the outer peripheral surface via the cylindrical body. A method for manufacturing a cylindrical LC noise filter, comprising forming a second conductor so as to face a conductor.