JPH01176109A - Multi-channel noise filter - Google Patents

Abstract

PURPOSE:To realize a compact multi-channel noise filter suitable for high density mount board by using a flat tubular noise filter to eliminate noise for each channel. CONSTITUTION:Plural split conductors 32a, 32b, 32c are wound into a tubular shape while the insulation layers are overlapped and smashed flat to form a noise filter 30 thereby making the thickness per one noise filter very thin. That is, the flat tubular noise filter 30 is easily formed by winding plural strip conductors 32a, 32b, 32c in several turns, at most, ten and several turns like vinegared rice rolled in layer and then smashing it. Thus, the thickness of one noise filter is made thinner than the multi-channel pitch of the signal path with sufficient margin. Thus, the noise filter can be mounted simply and surely without giving any hindrance to high density mounting on the high density mount board even against the multi-channel pitch of the signal path provided with very narrow pitch.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a multi-channel noise filter, particularly to a multi-channel noise filter provided in a multi-channel input/output path of a high-density mounting board.

[Prior Art] A high-density mounting board is a board for surface mounting on which various electrical and electronic components are mounted at high density, and is widely used, for example, in frame memory for image data storage and other applications by various companies. There is.

In particular, recent high-density mounting boards have become even more dense due to the miniaturization of electronic components, so it is possible to handle multi-channel signal paths provided on the board without reducing the mounting density of the board. It has been desired to develop a multi-channel noise filter that can be reliably and easily implemented.

FIG. 7<A) shows an example of a high-density mounting board, on which electronic components are mounted at high density to form various electric circuits.

Such a high-density mounting board 10 often inputs and outputs multi-channel signals to and from the outside via input/output terminals, and also inputs and outputs multi-channel signals between circuits formed on the board 10.
There are many cases where multi-channel signals are output manually.

Therefore, there are various multi-channel signal paths 1 on the board 10.
00 is set. In Fig. 7(B), 100-1, 10〇-2)...100-
An example of n n-channel signal paths is shown.

Various types of noise are often mixed into signals flowing through such a multi-channel signal path 100.

These mixed noises often cause malfunctions of each electric circuit provided on the board 10 and malfunctions of external devices connected to the board 10.

Therefore, in order to reliably remove noise components from each signal flowing through the multi-channel signal path 100, each of these signal paths 100-1, 100-2), . . . 100-n is provided with a noise filter.

In particular, in recent years, high-density mounting boards 10 have been formed with extremely high density as electronic devices have become smaller and lighter.
．． 100-2)...The pitch of 100-1 is narrowed to about several millimeters.

Therefore, there is a need to develop a small and inexpensive noise filter that can be easily and reliably attached to the multi-channel signal paths 100-1, 100-2)...100-n provided at such narrow intervals. There is.

FIG. 8(A) shows an example of a noise filter circuit mounted on the multi-channel signal path 100, and such a noise filter is usually formed by combining a coil L and a capacitor C. .

[Problems to be Solved by the Invention] However, as shown in FIG. 9, the conventional noise filter is formed by combining a capacitor element C and a coil element which are separately formed. For this reason, as described above, the multi-channel signal path 10 is provided with an extremely narrow width.
There is a problem in that the zero noise filter is large and expensive.

In particular, conventional noise filters use bead core coils as coil elements. This bead core coil is formed by using a ferrite called a bead core as a magnetic material and winding the coil around this flight.

For this reason, the diameter Φ of the coil element itself is at least approximately 1
For example, if each channel pitch d is extremely narrow, such as several millimeters, as described above, the thickness of the noise filter will exceed the channel pitch d. Therefore, when a conventional noise filter is used as a multi-channel noise filter for the high-density mounting board 10, there is a problem in that it causes a decrease in the assembly efficiency of the entire board, and furthermore, it becomes an obstacle to increasing the density of the board itself.

In addition to this, conventionally, a noise filter as shown in FIG.
2) Since it is necessary to install each unit every 100-n, there is a problem that the installation work becomes extremely complicated.

[Object of the Invention] The present invention has been made in view of the above-mentioned conventional problems, and its purpose is to solve the problem of high density mounting on a high-density mounting board even for multi-channel signal paths provided at extremely narrow pitches. It is an object of the present invention to provide a multi-channel noise filter which is small in size and can be mounted easily and reliably without hindering the increase in density, and which is efficient in mounting.

[Means for Solving the Problems] In order to achieve the above object, the present invention includes a plurality of flat tubular noise filters integrally formed by winding a plurality of strip-shaped conductors laminated with an insulating layer interposed therebetween. , a casing that accommodates a plurality of these flat tubular noise filters aligned in the thickness direction, and a multi-channel high-density mounting board provided in this casing, one end of which is connected to each noise filter, and the other end of which is connected to each noise filter. Multi-channel input/output terminals each connected to a signal path, and noise in a multi-channel signal path of a high-density mounting board is removed.

"Function" The present invention has the above-mentioned configuration, and its function will be explained next.

The present invention involves rolling a plurality of band-shaped conductors into a tubular shape by overlapping insulating layers, and crushing this into a flat shape to form a noise filter, thereby making it possible to extremely reduce the thickness of each noise filter. First feature 9: In other words, the flat tubular type noise filter can be easily manufactured by winding the plurality of band-shaped conductors described above in a spiral shape with several turns, at most ten or more turns, without crushing it into a flat shape. can be formed into For this reason, noise filter 1
The thickness of each individual signal path can be made thinner with a sufficient margin than the pitch interval of the multi-channel signal path described above.

A second feature of the present invention is that a plurality of flat tubular noise filters are packaged in a casing in a state in which they are aligned in the thickness direction, and one end of the casing is connected to each noise filter, and the other end is connected to a high This is because multi-channel input/output terminals are provided which are respectively connected to the multi-channel signal paths of the high-density mounting board.

By doing so, the multi-channel noise filter of the present invention is formed as a single-chip element in which the noise filters of each channel are housed at a high density, making it extremely suitable as a multi-channel noise filter for a high-density mounting board. .

Therefore, according to the present invention, it is extremely easy to attach a high-density mounting path to a multi-channel signal path, and the assembly process of a high-density mounting board can be simplified.

[Example] Next, preferred embodiments of the present invention will be described based on the drawings.

FIG. 2 shows a preferred example of a noise filter used in the present invention.

The first feature of the present invention is that the signal path 100 of each channel
As the noise filter 30 used in the present invention, a flat tubular type noise filter is used which is integrally formed by winding a plurality of strip-shaped conductors laminated with an insulating layer interposed therebetween.

By doing so, the noise filter 30 used for each channel can be made very small, and in particular, the thickness D of the noise filter 30 can be made extremely thin compared to the pitch d of each channel, and high-density packaging is possible. Substrate 10
3 filters on each channel without reducing packaging density.
FIG. 3 shows an example of such a flat tubular noise filter 30.

The noise filter 30 of the embodiment includes three strip-shaped conductors 32.
a, 32b, 32c, and each strip-shaped conductor 32a, 32b,
It has lead wires 34a, 34b, . . . , 34f connected to the ends of the band-shaped conductors serving as current-carrying conductors among the conductors 32c, and band-shaped insulators 36a, 36b, and 36c such as insulating sheets.

Then, the three strip-shaped conductors 32a, 32b, 32c
are rolled into a stacked tubular shape with band-shaped insulators 36a, 36b, and 36c interposed therebetween, and this is crushed into a flat shape as shown in FIG.

In this way, when the band-shaped conductors 32a, 32b, and 32C are overlapped and rolled into a flat tubular shape, each of these conductors 3
2a, 32b, and 32c each function as an independent coil, and capacitance exists between these coils in a distributed constant manner. As a result, the entire circuit functions as a noise filter consisting of L and C.

That is, the strip-shaped conductors 32a, 32b, 3 shown in FIG.
2c through insulating sheets 36a, 36b, and 36C to form a filter element, three strip-shaped conductors 32
Three capacitances are formed between a, 32b, and 32c, and these three strip-shaped conductors 32a, 32b, and 32
c will be inductively coupled to each other.

In the filter element configured in this way, one or two of the three strip-shaped conductors 32a, 32b, and 32c
By using one strip-shaped conductor as a current-carrying conductor and using the remaining strip-shaped conductor as a grounding conductor, this element can be utilized as a noise filter for various circuit configurations.

In this embodiment, as shown in FIG. 4<A>, two strip-shaped conductors 32a and 32c are used as current-carrying conductors, and the lead wires 34a and 34b at one end are taken out as input/output terminals, and the lead wires 34a and 34b at the other end are taken out as input/output terminals. Lead wires 34b and 34f are connected to each other. Furthermore, the lead wires 34d provided at one end of the other strip-shaped conductor 32b are taken out as ground terminals, and the lead wires at the other end are left open.

By doing this, the strip-shaped conductors 32a, 3
In addition to its inductance, 2c is a strip-shaped conductor 32b.
A capacitance is formed between the two in a distributed manner. As a result, the noise filter 30 can remove noise with an operation similar to that of a 1'' type filter having the circuit configuration shown in FIG. 8 (A>).

Furthermore, by connecting the band-shaped conductors 32a, 32b, and 32c as shown in FIG. 4(B), the noise filter 30 is similar to the π-type filter having the circuit configuration shown in FIG. 8(B). The movement will remove noise.

In this embodiment, each of the terminals 34a, 34e, 34
d, respectively, the input/output pins 30 as shown in FIG.
a, 30b and a grounding bin 30c are connected to form a noise filter 30.

Here, the values of the noise filter and C can be set to arbitrary values by selecting the number of turns and width of the strip-shaped conductor 32 and other conditions.

For example, assume that the noise filter 30 is for a multi-channel signal path with a pitch interval of d=1.25 mm, and the values of L and C are set to L=0.05 μH and C=183 pF, respectively. In this case, the noise filter can be formed by winding the band-shaped conductor '32 by four turns, and the dimensions of the noise filter 30 shown in FIG. , width L
= 5.0 mm, thickness 1) = about 1.2 mm, which made it extremely small.

Further, the noise filter 30 used in the present invention can be formed smaller in accordance with the pitch interval d of the multi-channel signal path used, for example, its thickness can be reduced to 1)=
It can also be about 0.05 mm. By forming it in this way, it is possible to make it sufficiently thinner than the pitch interval of the channel signal path 100 that will be used in the future, for example, about d=0.8 mm.

Jannel noise filter Therefore, such a flat tubular noise filter 30
If used as a noise filter in the multi-channel signal path 100, for example, as shown in FIG. -1.30
-2)...Even if 30-■ are placed adjacent to each other, each filter 3
0-1.3〇-2)...30-n can be installed with sufficient margin without interfering with each other.

Furthermore, the noise filter 30 used in the present invention has a thickness D of each signal 100-1.1002.100-n.
Since the pitch interval d can be made sufficiently thinner than the pitch interval d, shield plates 31-1, 31-2, .

However, multiple noise filters 30-1, 30-2)
...30-n as signal path 100-1.1 of each channel
00-2)...If each component is individually attached to 100-n, the number of components to be handled will be extremely large, making component management extremely troublesome, and will be a major factor in reducing the efficiency of assembly of the high-density mounting board 10. .

In particular, in the high-density mounting board 10, the signal paths 100-1, 100-2), . . . 100-n of each channel are laid out extremely close to each other.

For this reason, each noise filter 30-1, 30-2)...
・30-n for each signal path 100-1.100-2)
...100-N The work of accurately positioning and attaching each piece one by one is extremely time-consuming, and if this is to be done automatically using a machine, the assembly machine must have extremely high working accuracy. That will happen.

In particular, a plurality of noise filters 30-1.30-2)
...30-n individually for each signal path 100-1,100
-2)...100-n, it is necessary to connect the ground terminals 30c of each noise filter 30-1, 30-2)...30-n to the ground line 110 individually. This was also a major factor causing a decrease in assembly efficiency.

The second feature of the present invention is that a plurality of flat tubular noise filters 30-1, 30-2)...30-■ are packaged in a state in which they are aligned in the thickness direction to form a multi-channel noise filter. It's what I did.

FIG. 1(A) shows a preferred example of a multi-channel noise filter 200 according to the present invention. The multi-channel noise filter 200 of the embodiment uses a casing 40 to combine a plurality of flat tubular noise filters 30-
1.30-2)...30-n are integrally packaged in a state where they are aligned in the thickness direction.

Then, n-channel input terminals 42-1, 42-2)...
42-n, n channel output terminal 44-1.44-2
)...44-n and a common ground terminal 46 are formed to protrude.

Here, the input terminals 42-1, 42-2)...
42-n is an n-channel signal path 100-1.
100-2)... are provided at the same pitch as 100-n. One end side thereof is connected to the input side of the corresponding noise filter 30-1, 30-2), . . . 30-n.

In addition, the output terminals 44-1, 44-2)...44-
n is the signal path of n channels 100-1.100-2
)... are provided at the same pitch as 100-n. And one end side corresponds to each noise filter 3.
0-1.30-2)...Connected to the output side of 30-H.

Further, the common ground terminal 46 is provided at a position corresponding to the ground line 110 provided on the board 10, and is connected to the ground side of each noise filter 30-1, 30-2)...30-n. has been done.

By using the above +15 configuration, the multi-channel noise filter 200 of the present invention has a filter 3 of each channel.
0-1.30-2)...30-n are packaged and formed as one element. Therefore, when mounting a multi-channel noise filter on the high-density mounting board 10, the number of parts can be significantly reduced, and the management of parts can be made easier.

In particular, according to the present invention, a plurality of flat tubular noise filters 30-1 each having an extremely small size are provided.
30-2)...30-n are packaged as one element within the casing 40. Therefore, although the multi-channel noise filter 200 has an extremely high density, it can be made to a size that is neither too large nor too small, making it easy to handle as a mounted component.

Further, in the present invention, the multi-channel noise filter 200 is formed as a one-chip element. For this reason, mounting to the multi-channel signal path 100 requires complicated work such as individually positioning a large number of noise filters 30-1, 30-2, etc. using supports as shown in FIG. There is no need to perform any additional work, and only one element needs to be aligned.

Therefore, when automatically assembling the high-density mounting board 10,
It is possible to greatly increase the assembly efficiency and to simplify the automatic assembly equipment.

Furthermore, according to this embodiment, the casing 40 is provided with a common ground terminal 46 that is commonly connected to the ground sides of the noise filters 30-1, 30-2), . . . , 30-n. Therefore, it is sufficient to simply connect the ground terminal 46 to the ground line 110 on the board 10 side, and as shown in FIG.
Separately connect each grounding bin 30C to the common ground line 1.
10 can be eliminated, and from this point of view as well, assembly work efficiency can be improved.

Further, according to the present invention, the adjacent noise filters 30
A multi-channel noise filter 200 may be formed by providing a shield plate 31 for preventing crosstalk as shown in FIG. 5 between them.

Further, in the embodiment shown in FIG. 1, one end side of the common ground terminal 46 is connected to the ground line 110, but in addition to this, for example, the common ground terminal 46 can be grounded at two points on both ends thereof. If it is formed in such a way that it can be formed, the grounding efficiency can be further increased. Furthermore, if the grounding terminals 46 are formed so that they can be installed at multiple points, the grounding efficiency can be further improved.

In addition, in this embodiment, the casing 40 may be formed as a dedicated case for accommodating each noise filter, or for example, a plurality of noise filters 30-1, 30-2 arranged in an array. ...30-n can be formed by molding or by dipping.

In addition, in this embodiment, each terminal 42, 44, 46 is
For example, it is preferable to form using a lead frame 300 as shown in FIG.

For example, when forming a 7-channel noise filter 200, first, as shown in FIG.
4-2...44-7.46 are integrally formed. A lead frame 300 is prepared.

Next, noise filter 30-1.30 for 7 channels
-2...30-7 <not shown) for each terminal 42.44
．． Align the positions with the mounting holes a, b, and c provided in 46,
Solder.

Next, each noise filter 30 - up to the line 320 in the figure.
1. The casing 40 is formed by dipping or molding 30-2...30-7 together. Finally, each terminal 42, 44, 46 of the multi-channel noise filter 200 formed on the lead frame 300 is separated from the frame 310.

By using the lead frame 300 in this way,
Multi-channel noise filter 200 can be formed efficiently.

Note that the present invention is not limited to the embodiments described above, and various modifications can be made within the scope of the gist of the present invention. A specific example will be explained below.

(a) Other embodiments of filter In the embodiment described above, three strip-shaped conductors 32a, 32
Although the explanation has been given by taking as an example a case where a flat tubular type noise filter is formed by laminating B and 32c, the present invention is not limited to this, but a flat tubular type noise filter formed by winding four or more strip-shaped conductors. It is also possible to use At this time, noise filters with various circuit configurations can be formed by devising connections between the strip-shaped conductors.

Further, in the present invention, a flat tubular noise filter in which the band-shaped conductor is formed using a magnetic material may be used.

FIG. 10 shows an example of such a type of flat tubular noise filter, and this noise filter 30 consists of two strip-shaped magnetic conductors 38a and 38b formed into strips of insulating sheets such as capacitor paper. Insulator 36a
, 36b are placed on top of each other and rolled into a tubular shape.

By doing so, the two strip-shaped magnetic conductors 38a, 38b function as a coil, and a capacitor is distributed over the entire area between each of the strip-shaped magnetic conductors 38a, 38b forming the coil. It is formed. Therefore, the entire circuit functions as an L and C noise filter.

In the above embodiment, a three-terminal type noise filter 30 is used as the noise filter 30 for each channel. However, the present invention is not limited to this, and the flat tubular noise filter 30 having four or more terminals can also be used to form a multi-channel noise filter.

As such a noise filter 30 having four or more terminals,
For example, a plurality of ground terminals may be provided, and by providing a plurality of ground terminals in this manner, the noise filter 30 can have good attenuation characteristics over a wide band.

As shown in FIG. 12, the inventor has constructed a strip-shaped conductor 32a provided with input/output terminals 34a and 34b at both ends, and a strip-shaped conductor 32b for grounding provided with a grounding terminal 34c at one end. A noise filter 30 was formed using the same, and its attenuation characteristics were measured.

At this time, a strip-shaped conductor 32a used as a current-carrying conductor
The strip conductor 32b used for grounding is set to have a width of 6 mm and a length of 50 cm.
2>, 12.5 cm (band-shaped conductor 32b), and three types of noise filters 30 were formed.

The capacitances of samples of these three types of noise filters 30 at low frequencies between current-carrying and grounding conductors were 2.6 nF, 1.3 nF, and 0.7 nF, respectively.

When we measured the attenuation characteristics of these three types of noise filters 30 over a wide band of 400MHz, we found that
The characteristics shown in FIG. 13 were obtained.

As is clear from the figure, at relatively low frequencies of several tens of MHz, an attenuation characteristic is observed that is directly proportional to the length of the grounding strip conductor 32b. The length is 1/ of the total length of the current-carrying band-shaped conductor 32a.
It has been found that substantially the same attenuation characteristics can be obtained even when the value is about 4.

Therefore, such a tubular noise filter 3
0, excellent characteristics can be obtained even if the length of the grounding strip conductor 32b is short, and moreover, the grounding strip conductor 3
By shortening 2b, the amount of the required band-shaped conductor, such as aluminum foil, can be reduced by a factor of 11, and the dimensions of the noise filter 30, that is, the external shape, can be greatly reduced. can. Therefore, if such a noise filter 30 is applied to the present invention, the multi-channel noise filter can be made smaller and lighter.

By the way, as shown in the equivalent circuit of FIG.
It has been experimentally discovered that by providing a plurality of 2b's, excellent attenuation characteristics can be exhibited over a wide band. Here, each grounding strip conductor 32b-1, 32b
-2...32b-B need only be sufficiently shorter than the current-carrying band-shaped conductor 32a, and each of them should be grounded.

FIG. 14 shows an example of the noise filter 30 formed in this way, and the noise filter 30 is
A band-shaped conductor 32a for current carrying with a total length of 50 cm, and a band-shaped conductor 32b-1, 32 for grounding, which is divided into two and has a total length of about 20 cm.
b-2.

Here, the grounding terminals of the grounding strip conductors 32b-1 and 32b-2 are provided to match the input/output terminals of the strip conductor 23a, and the effect of each grounding strip conductive strip is utilized to the maximum. ing.

In addition, FIG. 7 shows a current-carrying conductor 32a with a total length of 50 cm.
and a grounding strip conductor 3 divided into three parts with a total length of about 13 cm.
2b-1, 32b-2, and 32b-3 are shown.

Further, in FIG. 16, a strip-shaped conductor 32a with a total length of 50 cm is shown.
A noise filter 30 is shown that is formed using grounding strip-shaped conductors 321b-1, 32b-2, 32b-3, and 32b-4 divided into four parts each having a total length of about 10 cm.

When the attenuation characteristics of each of these noise filters 30 were measured, it was confirmed that the noise filters 30 exhibited excellent attenuation characteristics over a wide band as shown in FIG. In the same figure,
E is the characteristic of the noise filter shown in FIG. 12 using one grounding strip conductor 32b, the same figure is the characteristic of the noise filter shown in FIG. 14, and the same figure F is the characteristic of the noise filter shown in FIG. 15. G in the figure shows the characteristics of the noise filter shown in FIG.

As is clear from the attenuation characteristics shown in FIG. 17, the attenuation characteristics of the divided ground type noise filter 200 each have two peak values. It is estimated that the first peak in the 33 low frequency band is due to distributed capacitance, and the second peak in the high frequency band is due to inductance.

When the total length of the current-carrying strip-shaped conductor 32a is constant, the first and second peak values become higher depending on the number of divisions of the grounding strip-shaped conductor 32b. In particular, in this measurement example, it can be seen that each time the number of divisions increases by one, the frequency of the second peak value decreases by about 100 MHz, and the degree of attenuation increases by about 10 dB. In addition, over a wide band of 400MHz, the first
Split grounding type noise filter 30 shown in Figs. 4 to 16
Both exhibit superior characteristics compared to the normal type noise filter shown in FIG.

Although FIGS. 14 to 16 all show cases in which the noise filter 30 is formed using one strip-shaped conductor 32a for current-carrying, two or more strip-shaped conductors for current-carrying may be used as necessary. Even if a noise filter is formed by combining the conductors 32a, similarly excellent attenuation characteristics can be obtained.

By the way, such a divided grounding type noise filter 30
A plurality of ground pins 30c are provided.

Therefore, such a divided grounding type noise filter 30
When forming the multi-channel noise filter 200 of the present invention using the above, it is sufficient to provide a plurality of common ground terminals 46 in accordance with the number of ground pins.

For example, when using a noise filter 30 having two ground pins 30c, two common ground terminals 46a are used as shown in FIGS. 1(B) and 1(C).

46b may be provided.

(b) Other Embodiments of Caging The present invention also provides each noise filter 38-1, 38-2) forming the multi-channel noise filter 200.
38-n and the casing 40 can also be formed separately.

FIG. 6 shows an example of a multi-channel noise filter 200 formed in this manner.

In the multi-channel noise filter 200 of the embodiment, the casing 40 is provided with an electrode socket 60 and a filter guide 50 corresponding to the noise filter 30 of each channel.

Each socket 60 is composed of three cylindrical electrodes 60a, 60b, 60c electrically connected to terminals 42, 44, 46, and pins 30a, 30b of the flat tubular noise filter 30 guided by a guide 50. , 30c are formed so as to be inserted into the respective cylindrical electrodes 60a, 60b, 60c.

By doing so, the multi-channel noise filter 200 of the embodiment can be mounted on the mounting board 1 with the noise filter 30 of each channel inserted into the casing 40 in advance.
Alternatively, each noise filter 30 may be inserted into the socket 60 after the casing 40 is attached to the signal path 100 in advance.

[Effects of the Invention] As explained above, according to the present invention, since a flat tubular noise filter is used to remove noise in each channel, the size of each filter, especially its thickness, can be reduced. It is possible to realize a compact multi-channel noise filter that can be made sufficiently thin and suitable for high-density mounting boards.

Furthermore, according to the present invention, since a plurality of flat tubular noise filters are packaged and configured as a single chip electronic component, the number of components required for a multi-channel noise filter is significantly reduced, and a high-density mounting board can be used. Parts management during assembly can be facilitated.

Furthermore, according to the present invention, since a plurality of flat tubular noise filters are arranged in the thickness direction and packaged inside the casing, the packaging density is high, but the size is not too large or too small. A multi-channel noise filter can be formed as an electronic component, and from this point of view as well, mounting on a high-density mounting board can improve work efficiency.

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram showing a preferred example of the multi-channel noise filter according to the present invention. C
) is an explanatory diagram when using multiple ground terminals, Figure 2 is an external perspective view of the flat tubular noise filter used in the multi-channel noise filter shown in Figure 1 <A>, and Figure 3 is an explanatory diagram of the case where multiple ground terminals are used. 4 is an explanatory diagram showing a specific example of the connection state of the noise filter shown in FIG. 3. FIG. 5 is an explanatory diagram of the flat tubular type noise filter shown in FIG. 2. An explanatory diagram when a noise filter is connected to a multi-channel signal path. FIG. 6 is an explanatory diagram showing another example of the multi-channel noise filter according to the present invention. FIG. 7 is an explanatory diagram showing an example of a high-density mounting board. Figure 8 (A) is an overall explanatory diagram, Figure 8 (B) is an enlarged explanatory diagram of the multi-channel part, and Figure 8 is an electrical circuit diagram of the noise filter.
> is the electrical circuit diagram of the T-type noise filter, and (B) is π
(C) is an electric circuit diagram of a divided grounding type noise filter. Figure 9 is an explanatory diagram of the external appearance of a conventional noise filter. Figure 10 is a flat tubular type noise filter according to the present invention. FIG. 11 is an explanatory diagram showing another configuration of the lead frame used in creating a multi-channel noise filter, and FIG. 12 is an explanatory diagram showing a lead frame used when creating a multi-channel noise filter. An explanatory diagram, Fig. 13 is a diagram of the attenuation characteristics of a noise filter obtained when the length of the grounding strip conductor is changed, Figs. 14 to 16 are explanatory diagrams of a split grounding type noise filter, Fig. 17 is an attenuation characteristic diagram of each noise filter shown in FIG. 12 and FIG. 14 to FIG. 16. 10; high-density mounting board; 30; flat tubular noise filter 32a, 3
2b, 32c; band-shaped conductors 36a, 36b, 36c
; Strip-shaped insulating bands 38a, 38b; Strip-shaped magnetic conductor 40; Casing 42-1.42-2)...42-n; Input terminal 44-1.44-2)...44-n; Output terminal 46; Common earth terminal 100-1.10--2)...100-n; Multi-channel signal path

Claims (4)

[Claims] (1) A plurality of flat tubular noise filters integrally formed by winding a plurality of strip-shaped conductors laminated with an insulating layer interposed therebetween, and a plurality of flat tubular noise filters arranged in alignment in the thickness direction. and a multi-channel input/output terminal provided in the casing, one end of which is connected to each noise filter, and the other end of which is connected to the multi-channel signal path of the high-density mounting board. A multi-channel noise filter that removes noise from multi-channel signal paths on a mounted board. (2) The filter according to claim (1) includes a common ground terminal provided on the casing so as to be commonly connected to the ground of each of the noise filters and connected to the ground path of the high-density mounting board. Features a multi-channel noise filter. (3) The filter according to any one of claims (1) and (2), characterized in that the multi-channel input/output terminals are provided at intervals matching the multi-channel signal paths of the high-density mounting board. Multi-channel noise filter. (4) In the filter according to any one of claims (1) to (3), the flat tubular noise filter includes a plurality of strip-shaped conductors and a strip-shaped insulator, and the plurality of strip-shaped A multi-channel noise filter characterized in that insulators are stacked with the strip-shaped insulator interposed therebetween and wound into a flat tubular shape, and the strip-shaped conductor is formed into a coil having distributed capacitance.