JP2001211048A - Lc noise filter - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a distributed constant type LC noise filter which has excellent electrical characteristics. SOLUTION: This LC noise filter includes an inductor conductor 12 which is formed spirally on one side of a dielectric substrate 10, and a plurality of grounding block conductors 50 which sandwich the dielectric substrate 10 and are disposed at a position which is free from blocking up the magnetic path of the inductor conductor 12 and parallel to the inductor conductor 12 only to face one part of the inductor conductor 12 so as to make a mutual inductance formed between a self-inductance and the inductor conductor 12 small.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to an improvement of a distributed constant type LC noise filter.

[0002]

2. Description of the Related Art Conventionally, as shown in FIG. 16A, an inductor conductor 12 is spirally formed on one surface 10a of an insulating substrate 10 made of ceramic or the like, and as shown in FIG. A noise filter in which a ground conductor 14 is formed on 10b is known.

In this noise filter, as shown in FIG. 17, a spiral inductor conductor 12 has an inductance L _1.
And the capacitance C is distributed between the spiral inductor conductor 12 and the ground conductor 14 in a distributed constant manner.
Functions as a noise filter.

[0004]

However, such a conventional LC noise filter has the following problems.

(A) First Problem This noise filter is composed of an inductor conductor 12 provided on the front side of a substrate 10 and a ground conductor 14 provided on the back side.
There is a problem that the capacitance C as expected cannot be obtained, and that only electrical characteristics worse than those of the lumped-constant type LC noise filter can be obtained.

In particular, when the frequency of a signal applied to the inductor conductor 12 increases, the inductance of the inductor conductor 12 changes, and the capacitance C between the inductor conductor 12 and the ground conductor 14 decreases. There was a problem that it could not be accomplished.

(B) Second problem When this noise filter is used in a signal circuit,
A signal is applied to the electrodes 16 and 18 at both ends of the inductor conductor 12 to remove noise contained in the signal. When the frequency of the signal to be applied increases, an arrow is applied to the spirally wound inductor conductor 12. There is a problem that a line short-circuit as shown by B occurs and the inductor conductor 12 does not function as an inductor.

In particular, such a line-to-line short-circuit phenomenon occurs more frequently as the frequency of a signal to be supplied becomes higher, and thus there is a problem that a conventional noise filter cannot be used as a high-frequency noise filter. Was.

The present invention has been made in view of such conventional problems, and an object of the present invention is to provide a distributed constant type LC noise filter having excellent electric characteristics to solve the above-mentioned problems. It is in.

[0010]

In order to solve the above-mentioned first problem, an LC noise filter according to the present invention comprises a spirally formed inductor conductor formed on one surface of a dielectric, and the above-described dielectric sandwiching the dielectric. It is arranged along the inductor conductor at a position that does not block its magnetic path, and faces only a part of the inductor conductor so as to reduce the self-inductance and the mutual inductance formed between the inductor conductor. And a plurality of earth block conductors arranged as described above.

In order to solve the above first and second problems, an LC noise filter according to the present invention comprises an inductor conductor spirally formed on one surface of a dielectric, and an inductor conductor sandwiching the dielectric between the inductor conductor. Along with a part of the inductor conductor so as to reduce the self inductance and the mutual inductance formed between the inductance conductor and the self-inductance, it is arranged at a position that does not block the magnetic path thereof. And a plurality of grounding block conductors, wherein a shield conductor for preventing a short circuit between the inductor conductors is provided between the conductors of the inductor conductor.

Next, the operation of the present invention will be described.

The present inventor has found that, for example, in the LC noise filter shown in FIG.
The reason why the expected capacitance C could not be obtained between 4 and 4 was examined. Then, the major cause is hypothesized to be in short-circuit current flowing through the ground conductor 14, studying about what inductance L ₁ and capacity thin drawers C of the LC noise filter shown in FIG. 17 is actually working Was.

In this LC noise filter, a ground conductor 14 is capacitively coupled to a spiral inductor conductor 12 by electrostatic capacitance and inductively coupled. Therefore, the magnetic flux generated by the current flowing through the inductor conductor 12 causes the ground conductor 14
An electromotive force is also generated on the upper side, and the electromotive force causes a short-circuit current as indicated by a solid line A to flow.

(A) Consideration of capacitance First, the reason why the expected capacitance C cannot be obtained between the inductor conductor 12 and the ground conductor 14 will be examined.

If the spiral inductor conductor 12 is compared to a primary coil in a transformer, the ground conductor 14 acts like a short-circuited secondary coil, and even though the ground conductor 14 is formed on a plane, the ground conductor 14 has the same shape. The inductance component becomes unexpectedly large.

Therefore, the accurate equivalent circuit of the conventional LC noise filter shown in FIG. 16 is not as shown in FIG. 17, but is actually as shown in FIG. In this, L ₁ is the inductance of the inductor conductor 12, L _E is a distributed constant manner capacitance formed between the inductance, C is the two conductors 12 and 14 of the ground conductor 14.

If the capacitance C is Ca, C
Let us consider three lumped capacitors b and Cc.
The inductance L _E of the ground conductor 14 increases, the capacitance Cb that is located away from the ground terminal 20,
Cc energized by both the inductance L _E is is prevented. Therefore, only the capacitance Ca of the ground conductor 14 near the ground terminal 20 acts as the capacitance of the noise filter.

Therefore, the conventional LC noise filter is
It is considered that only the capacitance of Ca is obtained when viewed as a filter, and the expected capacitance C cannot be obtained due to its structure.

Further, since a substantial capacitance can be formed only in a portion of the ground conductor 14 close to the ground terminal 20, the area of the ground conductor 14 shown in FIG. , The substantial characteristics as a noise filter hardly change, and any capacitance C
There is also a problem that it is difficult to obtain an LC noise filter having the following.

(B) Study on Inductance Next, the inductance of the inductor conductor 12 will be examined.

As described above, this LC noise filter is configured such that the spiral inductor conductor 10 is connected to the ground conductor 14.
Are capacitively coupled by capacitance and are inductively coupled.
Therefore, the inductor conductor 12 in addition to the self-inductance L _1, the mutual inductance M between the ground conductor 14 will act. In particular, when the area of the ground conductor 14 is increased as in the related art, the mutual inductance M becomes too large, and it is considered that the inductor conductor 12 cannot sufficiently function as an inductor for an LC noise filter.

Further, since the conventional ground conductor 14 on the plane is opposed to the entire surface of the spiral inductor conductor 12, it blocks the magnetic path of the inductor conductor 12 and increases its magnetic resistance. Therefore, the expected inductance is not obtained in the inductor conductor 12, which is also considered to be a major factor in reducing the function as a noise filter.

As is apparent from the above-described studies (a) and (b), the conventional LC noise filter cannot obtain sufficient capacitance and inductance when viewed from the whole circuit, and the lumped-constant LC noise filter cannot be obtained. It will be appreciated that only worse properties can be obtained.

(C) Investigation of the present invention In view of the above fact, how the ground conductor functioning as a capacitor on the other surface of the dielectric is changed with respect to the inductor conductor formed spirally on one surface of the dielectric. The study was conducted to determine whether or not it would be possible to obtain an LC noise filter having good characteristics.

The inventor of the present invention provided one or a plurality of ground block conductors so as to oppose a part of the intactor conductor with a dielectric material interposed therebetween, thereby forming an LC noise filter.

[0027] The grounding block conductor can be used small self-inductance L _E because the area is small, as it is a noise filtering capacitor the capacitance formed between the Intakuta conductor.

Further, since the ground block conductor faces only a part of the inductor conductor, mutual inductance between the inductor conductor and the ground block conductor can be almost ignored, and the characteristic of the noise filter can be reduced. , An LC noise filter that does not include the mutual inductance that reduces the noise can be configured.

Further, since the ground block conductor only faces a part of the inductor conductor and does not block the magnetic path of the inductor conductor, the inductance of the inductor conductor does not decrease.

Therefore, the LC noise filter of the present invention is
An LC noise filter having sufficient L and C and having a small mutual inductance that adversely affects characteristics can be obtained.

An experiment was conducted using this LC noise filter. As a result, even with the provision of one earth block conductor, characteristics superior to those of the conventional LC noise filter shown in FIG. 16 could be obtained. In addition, when a plurality of block conductors for grounding are provided, each block conductor individually forms a capacitor that functions effectively with the inductor conductor. Therefore, by providing an arbitrary number of these earth block conductors, an LC noise filter having a desired capacitance can be obtained.

Further, according to the present invention, by providing a plurality of the block conductors for grounding, an LC having a distribution constant approximation which cannot be obtained by a conventional filter can be obtained.
The characteristics as a noise filter can also be obtained.

The present inventor further studied and found that the position of the grounding block conductor facing the inductor conductor greatly affected the attenuation characteristics of the noise filter. It has been confirmed that excellent attenuation characteristics can be obtained by arranging the conductor at a position closer to the input or output terminal of the conductor in terms of an electric circuit.

Therefore, when one grounding block conductor is provided, it may be disposed close to one of the input and output terminals of the inductor conductor.

When a plurality of grounding block conductors are provided, one of them is arranged close to the input terminal of the inductor conductor, the other is arranged close to the output terminal, and the other is opposed to another position. It should just be arranged.

Further, by forming a shield conductor which is located between the lines of the inductor conductor and prevents short-circuit between the lines of the inductor conductor, the inductor conductor functioning as an inductor can be used as a conventional line conductor even in a high frequency region. It was confirmed that no short circuit occurred during the operation, and the circuit sufficiently functioned as an inductor.

Thus, according to the present invention, it is possible to obtain an LC noise filter having excellent electrical characteristics from a low frequency range to a high frequency range.

[0038]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will now be described in detail with reference to the drawings.

[First Embodiment] FIG. 1 shows a first preferred embodiment of a distributed constant type LC noise filter according to the present invention.

The LC noise filter of the embodiment is shown in FIG.
(A) As shown in FIG.
An inductor conductor 12 functioning as an inductor is spirally formed on one surface 10a. The outer end of the spiral inductor conductor 12 is connected to the terminal 16 as it is,
Its inner end is connected to a terminal 1 via a jumper wire or a lead 17.
8 is connected.

A first feature of the present invention is that, as shown in FIG. 1B, one or a plurality of grounds are provided on the other surface 10b of the insulating substrate 10 so as to face a part of the inductor conductor 12. That is, the block conductor 50 is provided.

In this embodiment, 50-1, 50-2,... 50
-4 four ground block conductors are provided.

In this case, one of the ground block conductors 50-1, 50-2,..., 50-4 is connected to one of the terminals 16 of the inductor conductor 12 in an electric circuit position. 12 and is preferably arranged opposite to the other block conductor 50.
At a position closer to the other terminal 18 in terms of electric circuit,
It is preferable to dispose it so as to face the inductor conductor 12.

Therefore, the ground block conductor 50
-1 is provided so as to face a part of the region 12-1 located at a position close to the terminal 16 of the inductor conductor 12 on the electric circuit. Further, the block conductor 50-4 is provided so as to face a part of the region 12-4 which is located close to the terminal 18 of the inductor conductor 12 on the electric circuit.
Further, the remaining two block conductors 50-2 and 50-3 are respectively formed in partial regions 2-2 and 12-2 of the inductor conductor 12.
-3, respectively.

In this case, at least the input / output terminal 1
Grounding block conductor 50- disposed close to 6, 18
From the viewpoint of obtaining good attenuation characteristics, it is preferable that the leads 1-1 and 50-4 lead out the leads 51-1 and 51-4 from positions near the terminals 16 and 18 and connect them to the ground terminal 20.

Each block conductor 50 is formed to be slightly wider than the opposing inductor conductor 12.

FIG. 2 is an equivalent circuit diagram of the LC noise filter of the present embodiment. In the embodiment, the spirally formed inductor conductor 12 functions as the inductor L1. In addition, each of the ground block conductors 50-1, 50 facing each other across the inductor conductor 12 and the substrate 10 is provided.
,..., 50-4 are the respective regions 12 of the inductor conductor 12.
Capacitively coupled by the electrostatic capacitance between the -1,12-2,12-3,12-4, to form a capacitor _{C 1, C 2, C 3} , C 4.

In particular, according to the present invention, each of the ground block conductors 50-1, 50-2,..., 50-4 is formed in a block shape having a small area, and is connected to the ground terminal 20. Therefore, each block conductor 50-1, 50-2,
Since the eddy current flowing through... 50-4 is small and the inductance thereof is small, the capacitors C ₁ , C ₂ ,... C ₄ are directly connected to the ground terminal 20. As a result, the state is the same as when a plurality of LC noise filters are connected in series, and an LC noise filter that functions substantially as a distributed constant type can be obtained.

Therefore, according to the present invention, it is possible to increase the capacitance C by increasing the number of the block conductors 50 for grounding, and to decrease the capacitance C by reducing the number of the block conductors 50. A noise filter can be obtained.

Each of the ground block conductors 50-
, 50-2,... Have a small area and a part of the regions 12-1, 12-2, 12-
It is only arranged facing 3, 12-4. Therefore, the inductor conductor 12 and each ground block conductor 5
The mutual inductance between 0-1, 50-2,... 50-4 can be almost neglected, and the mutual inductance component that contributes to the deterioration of the characteristics of the noise filter can be greatly reduced.

Further, in the noise filter of the present invention, the ground block conductor 50 is formed so as not to obstruct the magnetic path of the inductor conductor 12.

That is, the magnetic flux generated when the inductor conductor 12 is energized,
0 passes from the front side to the back side and vice versa.
At this time, if the block conductor 50 is provided so as to obstruct the magnetic path (for example, if the block conductor 50 is provided so as to face the inter-line region of the inductor conductor 12), the magnetic path is changed to the block conductor 50. And the inductor conductor 12 cannot function sufficiently as an inductor.

On the other hand, by providing each of the block conductors 50 so as to face the inductor conductor 12 as in the present invention, the magnetic path of the inductor conductor 12 is not obstructed by the block conductor 50 at all. The effect of the LC noise filter can be sufficiently exhibited without lowering the inductance of the inductor conductor 12.

Therefore, the terminals 16 of the inductor conductor 12,
If 18 is used as an input / output terminal, it can be used as a normal mode noise filter having good electrical characteristics.

In this embodiment, each of the ground block conductors 50-1, 50-2,..., 50-4 is formed wider than a part of the opposing inductor conductor 12. (Length, length) may be arbitrarily set as necessary.

[Second Embodiment] FIG. 3 shows a preferred second embodiment of the present invention.

The LC noise filter of the embodiment is shown in FIG.
As shown in FIG. 2A, two sets of inductor conductors 12a and 12b are formed in a spiral shape on the surface 10a of the substrate 10.

As shown in FIG. 3B, on the back surface 10b side of the substrate 10, a group of ground block conductors 50a-1, 50a facing a part of one inductor conductor 12a is provided.
50a-4 are provided in the same manner as in the first embodiment. Similarly, a group of ground block conductors 50b- opposing a part of another inductor conductor 12b-
., 50b-4 are provided similarly to the first embodiment.

In this case, the ground block conductors 50a-1, 50a-2,... 50a-4 are connected to the respective portions 12a-1, 12a-2,.
2a-4 are arranged to face each other. Also, other grounding block conductors 50b-1, 50b-2,... 50b
-4 indicates each part 12b of the other inductor conductor 12b.
, 12b-2, ..., 12b-4.

In the same figure, 16a and 18a are input / output terminals of one inductor conductor 12a,
18b is an input / output terminal of the other inductor conductor 12b.

FIG. 4 shows an equivalent circuit diagram of the LC noise filter of the present embodiment. In this embodiment, the spirally formed inductor conductor 12a functions as a _first inductor L1. The inductor conductor 30b formed in a spiral shape functions as a _second inductor L2.

A group of ground block conductors 50a-1, 50a-2,... Provided on the back side of the substrate 10 is provided.
50a-4 during in the capacitor C ₁ so as not to disturb the magnetic _{path, C 2, C 3, C} 4 a distributed constant formed between one inductor conductor 12a which faces sandwiching the substrate 10 I do.

Similarly, another group of ground block conductors 50b-1, 50b-
2, ... 50b-4 reveals that between the other inductor conductor 12b, a capacitor C ₅ so as not to disturb the magnetic _{path, C 6, C 7, C} 8 to the distributed constant manner.

Accordingly, the noise filter of the present embodiment functions as a distributed constant type common mode type four-terminal noise filter having a circuit configuration as shown in FIG.

In this embodiment, the case where four ground block conductors 50 are provided for each of the inductor conductors 12a and 12b has been described as an example. However, the present invention is not limited to this, and the present invention is not limited thereto. By increasing or decreasing the number of the earth block conductors 50, it can be used as a distributed constant type common mode noise filter having an arbitrary capacitance.

Third Embodiment The first and second embodiments can solve the first problem described in the section for solving the problems, but can solve the second problem. It is not possible.

FIGS. 5 and 6 show a third preferred embodiment of the present invention which has solved such a problem.

The feature of this embodiment is that in the noise filter shown in FIG. 1, the shield conductor 40 is formed spirally between the lines of the inductor conductor 12 formed on one surface 10a of the substrate 10.

A through hole 42 is provided at the center of the substrate 10 as shown in FIG.
0 is connected to the substrate 10 through the through hole 42.
Earth block conductor 50 provided on the other surface 10b side
-4.

With the above configuration, the noise filter of this embodiment solves the first and second problems, and has excellent electrical characteristics from a low frequency band to a high frequency band as shown in FIG. It functions as a normal mode three-terminal noise filter.

Further, in the noise filter of the present embodiment, by providing the shield conductor 40, the inductor conductor 1
In addition to preventing the short circuit between the conductors 2 and 3, the inductance of the inductor conductor 12 and the capacitance formed between the conductors 12 and 50 are improved, and a more excellent damping characteristic than the first embodiment is exhibited. it can.

[Fourth Embodiment] FIG. 7 shows a preferred fourth embodiment of the present invention.

The feature of the present embodiment is that in the noise filter shown in FIG. 3, the first shield conductor 40a is formed in a spiral shape between the inductor conductors 12a and 12b, and the first shield conductor 40a is formed between the inductor conductors 12b and 12a. In the same manner, the second shield conductor 40b is similarly formed in a spiral shape to shield between the inductor conductors 12a and 12b.

The shield conductors 40a and 40a
The inner end of Ob is electrically connected to ground block conductors 50a and 50b provided on the back surface 10b side of the substrate 10 through through holes 42a and 42b provided in the center of the substrate 10. .

By doing so, according to the present embodiment, a common mode type four-terminal noise filter having excellent electrical characteristics from low frequency to high frequency as shown in FIG. 8 can be obtained. Thus, better attenuation characteristics can be obtained as compared with the second embodiment.

[Fifth Embodiment] FIG. 9 shows a preferred fifth embodiment of the present invention.

This embodiment is characterized in that, as shown in FIG. 9B, each of the ground block conductors 50-1, 50-2,.
0-4 is formed wider, and as shown in FIG.
Each of the regions 12-1, 12-2,..., 12-4 of the inductor conductor 12 facing the block conductor 50 is formed wide.

[0078] Thus, the inductor conductor 12, the block conductors 50-1, 50-2, ... opposing area between 50-4 becomes wide, the capacitance between the two C _1, C _2, ...
C ₄ can be a larger value.

FIG. 9 is a modified example of the embodiment shown in FIG. 1, but a similar method is used in the second embodiment to the second embodiment.
It goes without saying that the present invention can be applied to the fourth embodiment.

On the substrate 10, irregularities are formed in advance by, for example, etching in the regions where the regions 12 and the ground block conductors 50 are to be provided, and the substantial area is increased. By forming the conductor 50 and the inductor conductor 12, the facing area between the block conductor 50 and the inductor conductor 12 is increased,
The capacitance C can be increased.

Sixth Embodiment In the LC noise filter of the present invention, the number of turns of the inductor conductor 12 and the number of
By appropriately selecting the material, the inductance L and the capacitance C of the noise filter can be arbitrarily set.

For example, when it is desired to increase the inductance L, the substrate 10 may be formed using a magnetic material or the like. When it is desired to increase the capacitance C, the substrate 10 may be formed of a ceramic or other material having a high dielectric constant. What is necessary is just to form using a material. In order to increase both L and C, the substrate 10 may be formed using both a material having a high dielectric constant and a magnetic material.

In addition, when the inductance L is increased, the noise filter formed as in the first to fifth embodiments may be housed in a housing forming a magnetic circuit.

FIG. 10 shows an example of the noise filter formed as described above. The characteristic of this noise filter is that the noise filter is provided in a housing 80 formed of a magnetic material. The noise filter 210 shown in FIG.

In this case, a magnetic core insertion hole 10c is formed substantially at the center of the substrate 10, and the magnetic core 82 provided at the center of the housing 80 is inserted into the insertion hole 10c. Then, a lid 84 is placed on the housing 80 from above, thereby forming a closed magnetic path dedicated to the noise filter between the magnetic core 82 and the housing 80 and the lid 84 provided around the magnetic core 82.

Thus, the noise filter according to the present embodiment has an LC having a sufficiently large inductance.
It will be formed as a noise filter.

In this embodiment, the case where the closed magnetic circuit is formed using the housing has been described as an example. However, the present invention is not limited to this, and the magnetic circuit may be an open magnetic circuit if necessary. A housing may be formed.

FIG. 11 shows an example of a noise filter in which the surface of the substrate 10 is powder-coated with a magnetic material.

In the noise filter of this embodiment, a magnetic core insertion hole 10c is formed substantially at the center of the substrate 10, and the front and back surfaces of the substrate 10 are powder-coated with magnetic powder. As a result, the powder coating layer 86 forms a closed magnetic path dedicated to the noise filter, and the magnetic flux leaking to the outside can be significantly reduced.

As a result, even when a plurality of the noise filters are arranged adjacent to each other and used as another channel noise filter, the noise filters of the present embodiment are less likely to cause mutual interference such as ringing as adjacent noise filters, and are excellent. Electrical characteristics can be exhibited.

[Embodiment of PC Board] As shown in the first to fifth embodiments, the present invention uses a distributed constant type LC noise filter having good electric characteristics by using both sides of the insulating substrate 10. For example, if a PC board or the like is used as the insulating substrate 10, an arbitrary number of distributed constant type LC noise filters can be provided on the PC board without increasing the thickness of the PC board itself. .

Accordingly, by forming the distributed constant type noise filter of the present invention on a PC board, it becomes very suitable as a noise filter for various electronic devices which are required to be further reduced in size and weight in recent years. By forming the filter on a PC board, it is possible to greatly reduce the thickness and weight of the entire device as compared with the case where a conventional chip-type noise filter is used. In addition, as a PC board, you may use a film-shaped or sheet-shaped thing as needed other than a normal board | substrate.

Therefore, by using the distributed constant type LC noise filter of the present invention in, for example, a laptop computer, the size and weight of the laptop computer can be further reduced.

Further, if the LC noise filter of the present invention is applied to a PC board (constituted of a film substrate) for an IC card and the like in which a noise filter cannot be mounted conventionally due to a required thickness constraint, Any number of LC noise filters can be easily implemented.

The distributed constant type LC noise filter of the present invention can be formed by simply performing printed wiring on a PC board.
It can be easily mounted on the C board without increasing its thickness.

FIG. 12 shows a preferred embodiment in which a multi-channel noise filter for signal lines is formed on a PC board.

In the embodiment, a plurality of ICs 110 are mounted on the PC board 100.
And a plurality of signal lines 112 are connected to the substrate 110.

Under the PC board 100, a PC board 200 provided with a multi-channel noise filter is stacked. This PC board 200 is provided with each IC
A plurality of LC noise filters 210 of any of the first to fifth embodiments are formed at positions corresponding to the input / output leads 112 of the 110. Thus, a multi-channel noise filter corresponding to the lead 112 of each IC 110 is formed on the PC board 200.

Such a multi-channel noise filter 210 can be easily formed on the PC board 200 by using a method such as printing, for example, and its size is small in accordance with required L and C. It can be formed in space.

The PC board 200 thus formed is stacked on the PC board 100, and is electrically connected to each lead 112 of the IC 110 located above the PC board 200.

As described above, according to this embodiment, a multi-channel noise filter can be formed on the PC board 200 without increasing the thickness of the PC board 200, and the size and weight of the electronic device itself can be reduced. Can be planned.

Although the embodiment has been described by taking as an example the case where the multi-channel noise filter 210 is formed on a board 200 different from the PC board 100 provided with the IC 110 and the like, the present invention is not limited to this. If there is room on the PC board 100 on which the IC 110 is mounted, the multi-channel 21
0 may be formed.

In this embodiment, the case where a multi-channel noise filter for a signal line is formed on the PC board 200 has been described as an example. However, a noise filter for a power supply line may be formed as necessary. You can also.

FIG. 13 shows a PC on which the IC 110 is mounted.
On the board 100, a multi-channel noise filter 210 for signal lines and a noise filter 2 for power lines
An example in which the circuit board 20 is formed is shown, and the PC board 100 having such a circuit configuration is extremely suitable as a PC board for an IC card. When there are a plurality of ICs 110, the power line noise filter 220 may be formed as a multi-channel noise filter in accordance with the number of ICs 110.

In particular, in a portable device such as an IC card which does not have a sufficient grounding case, it is preferable to use the common mode noise filter shown in the fourth embodiment.

FIG. 14 shows an example in which a plurality of the noise filters shown in the first to fifth embodiments are provided on an insulating substrate 10 formed in a rectangular shape and formed as a multi-channel noise filter 300. ing.

The multi-channel noise filter 30 of the embodiment
0 can be easily mounted and mounted on the PC board 100 like ordinary electronic components, and can be used for, for example, a multi-channel noise filter for ICs and other uses. Alternatively, a film substrate may be used as the insulating substrate 10, and the film substrate 10 provided with the multi-channel noise filter on the PC board 100 may be mounted horizontally without standing as illustrated. Thus, even when the PC board 100 is installed in a place where the thickness is limited, the multi-channel noise filter can be mounted without increasing the thickness of the PC board 100.

Further, the noise filter of the present invention can be used not only as a noise filter for a signal line but also as a noise filter for a power supply line, for example, for an IC power supply line. As described above, as the insulating substrate used for the noise filter of the present invention, a film-shaped or sheet-shaped insulating substrate or another type of insulating substrate may be used as necessary.

Note that the present invention is not limited to the above-described embodiment, and various modifications can be made within the scope of the present invention.

For example, when the noise filter of the present invention is formed as an SMD type element, it is conceivable that a single noise filter may not be able to obtain sufficient L and C required. In this case, by stacking a plurality of noise filters and connecting each noise filter in series or in parallel, L having arbitrary C and L can be obtained.
A C noise filter can be obtained.

In the case of providing a large number of block conductors for grounding in the LC noise filter of the present invention, how to connect each block conductor to a ground terminal becomes a problem.

In this case, for example, FIG.
As shown in (B), the inductor conductor 12 is provided on the surface 10a.
The auxiliary substrate 96 is prepared in addition to the insulating substrate 10 provided with a and 12b and a large number of grounding block conductors 50 on the back surface 10b. The auxiliary substrate 96 is provided with a large number of electrodes 92 in contact with the block conductors 50 on the front surface 96a, and with leads 98 for connecting the electrodes 92 and the ground terminal 20 via through holes on the back surface 96b. Then, the back surface 10b of the substrate 10 and the front surface 96a of the auxiliary substrate 96 are stacked so as to overlap each other, and this is integrally dipped.

As a result, even when a large number of ground block conductors 50 are present, they can be easily connected to the lead terminals 20.

In each of the above embodiments, the short circuit between the inductor conductors used as the current-carrying conductors was prevented by using the shield conductors. In addition to this, the present invention covers the surface 10a of the substrate 10 provided with such a conductor, or both the surface 10a and the back surface 10b of the substrate 10 with an insulating shield layer so as to reduce the line-to-line short-circuit phenomenon. It can be more effectively prevented.

In this embodiment, the substrate 10 is formed using a material such as a high-frequency absorption heating element, so that noise generated from a signal passing through the inductor conductor 12, particularly high-frequency noise, is absorbed as heat. Thus, it is possible to more effectively remove noise.

Further, as the substrate 10, a ceramic material used for a varistor for taking a lightning surge or the like can be used if necessary.

In each of the above embodiments, the inductor conductor 12, the shield conductor 40, and the ground block conductor 5 are used.
By forming a magnetic conductor by bonding a magnetic body to the surface of the zero by plating or the like, the magnetic resistance of the inductor conductor 12 is reduced, and the inductance thereof can be increased.

Further, in the above-described embodiment, the case where the dielectric is formed as the substrate 10 has been described as an example. However, the present invention is not limited to this. For example, a cylindrical dielectric such as a cylinder or a square cylinder may be used. May be used. In this case, a plurality of spiral grooves may be provided on one of the inner and outer surfaces of the cylindrical body, and the inductor conductor may be formed in this groove. Also, inductor conductors may be formed on both the inner and outer circumferences of the cylindrical body.

[0119]

As described above, according to the present invention,
One or a plurality of ground block conductors are provided so as to face a part of the inductor conductor with the dielectric therebetween, and capacitors are individually formed between each block conductor and the inductor conductor. This makes it possible to obtain an LC noise filter that is composed of the inductance of the inductor conductor and the capacitor of each block conductor and functions well as a distributed constant type.

Further, according to the present invention, a distributed constant type LC noise filter having an arbitrary capacitance can be easily obtained by increasing or decreasing the number of the block conductors.

Further, according to the present invention, by providing a shield conductor for preventing this line-to-line short-circuit between spiral inductor conductors, noise components can be removed without causing a line-to-line short-circuit even in a high frequency band. Distributed constant type L
A C noise filter can be obtained.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram of a first preferred embodiment of a distributed constant type LC noise filter according to the present invention, and FIG.
Is an explanatory diagram of the front surface of the substrate, and FIG.

FIG. 2 is an equivalent circuit diagram of the noise filter shown in FIG.

FIGS. 3A and 3B are explanatory diagrams of a second preferred embodiment of the LC noise filter according to the present invention. FIG. 3A is an explanatory diagram of a front surface side, and FIG. FIG.

FIG. 4 is an equivalent circuit diagram of the LC noise filter shown in FIG. 3;

FIG. 5 is an explanatory view of a third preferred embodiment of the present invention. FIG. 5 (A) is an explanatory view of the front side, and FIG. 5 (B) is an explanatory view of the back side. .

FIG. 6 is an equivalent circuit diagram of the LC noise filter shown in FIG.

FIGS. 7A and 7B are explanatory views of a preferred fourth embodiment of the present invention, wherein FIG. 7A is an explanatory view of the front side and FIG. 7B is an explanatory view of the back side. . ,

FIG. 8 is an equivalent circuit diagram of the LC noise filter shown in FIG. 7;

FIG. 9 is an explanatory view of a fifth preferred embodiment of the present invention. FIG. 9A is an explanatory view of an example of a front surface, and FIG. 9B is an explanatory view of an example of a back side thereof.

FIG. 10 is an explanatory view of a sixth preferred embodiment of the LC noise filter according to the present invention formed using a housing.

FIG. 11 is an explanatory diagram of an LC noise filter in which a magnetic material is powder-coated to form a closed magnetic circuit.

FIG. 12 is an explanatory diagram of a case where PC boards are stacked and arranged, and a multi-channel noise filter is formed using one of the noise filters according to the first to fifth embodiments.

FIG. 13 shows a circuit board on which a IC is mounted.
FIG. 4 is an explanatory diagram in a case where both a multi-channel noise filter for a signal line and a noise filter for a power supply line are formed.

FIG. 14 is an explanatory diagram of a case in which a multi-channel noise filter is formed on a vertically long insulating substrate and mounted on a PC board.

FIG. 15 is an explanatory diagram of another embodiment of the present invention.

FIG. 16 is an explanatory diagram illustrating an example of a conventional noise filter.

FIG. 17 is an equivalent circuit diagram of the conventional noise filter shown in FIG.

FIG. 18 is an equivalent circuit diagram of the conventional noise filter shown in FIG.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Insulating board 12 Inductor conductor 40 Shield conductor 50 Grounding block conductor

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) H03H 7/075 H01G 4/40 321A

Claims (4)

[Claims] 1. An inductor conductor spirally formed on one surface of a dielectric, and disposed at a position sandwiching the dielectric so as not to block a magnetic path along the inductor conductor. A plurality of ground block conductors arranged so as to oppose only a part of the inductor conductor so as to reduce mutual inductance formed between the inductor conductor and the inductor conductor. filter. 2. An inductor conductor spirally formed on one surface of a dielectric, and disposed at a position sandwiching the dielectric along the inductor conductor so as not to block its magnetic path. And a plurality of ground block conductors arranged so as to oppose only a part of the inductor conductor so as to reduce mutual inductance formed between the inductor conductor and the inductor conductor. Characterized by providing a shield conductor for preventing a short circuit between inductor conductors.
C noise filter. 3. The device according to claim 1, wherein a portion of the inductor conductor facing the block conductor for grounding is formed wide, and a capacitance between the inductor conductor and each block conductor for grounding is increased. An LC noise filter characterized in that: 4. The method according to claim 1, wherein the inductor conductor includes two sets of inductor conductors formed on one surface of the dielectric so as to be adjacent to each other, and is formed as a common mode type. Characteristic LC noise filter.