JPH0438573Y2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a noise filter device including a number of inductances and a number of capacitors.

[Prior Art] In digital signal processing circuits of various electronic devices that handle digital signals, the input conductors thereof are easily affected by external noise, and there is a possibility that an erroneous input due to external noise will be processed as a correct input signal.

In order to eliminate the influence of such external noise, an inductance element is constructed by passing the input conductor of the signal processing circuit through a ferrite bead (cylindrical ferrite), and a capacitor is also connected between the signal line and ground. It is known to connect.

Further, as shown in FIG. 14, a ferrite block 1 having a through hole and a ground plate 2 having a through hole are provided.
and a dielectric substrate 3 having a through hole,
Individual electrodes 4 are provided on the upper surface of the dielectric substrate 3 to surround the through holes, a common electrode is provided on the lower surface of the dielectric substrate 3, and an inverted U-shaped conducting wire 5 is inserted into each pair of through holes. Solder the individual electrode 4 to the conductor 5 (not shown)
The two inductances L1 and L2 and one capacitor C shown in FIG.
1 and C2, which has a substantially T-shaped configuration, has been proposed in Japanese Utility Model Application No. 131284/1984.

[Problem to be solved by the invention] By the way, in the case of configuring a noise filter using the former individual ferrite beads and individual capacitors, it is necessary to prepare a large number of ferrite beads and capacitors for a large number of signal lines. This makes assembly difficult.

On the other hand, the latter noise filter device using the dielectric block 1 and the dielectric substrate 3 has the advantage of being easy to assemble and can be miniaturized. When one leg and the other leg face each other via a common ferrite block 1, mutual interference occurs (a phenomenon in which noise absorbed by one leg enters the other leg), making it impossible to effectively remove noise. It has its drawbacks.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide a noise filter device that can be miniaturized, is easy to assemble, and has an excellent noise removal effect.

[Means for Solving the Problems] To achieve the above object, the present invention will be described with reference to the reference numerals in the drawings showing the embodiments. The insulating magnetic block 11 and the plurality of through holes 19 that are juxtaposed to the first insulating magnetic block 11 and corresponding to the plurality of through holes 18 of the first insulating magnetic block 11 are aligned. The second insulating magnetic block 12 is disposed in a substantially U-shape having a pair of legs 17a, 17b and a top 17c, with one leg 17a being connected to the first insulating magnetic block 12. A plurality of inverted U-shaped conducting wires 17 are inserted into the through holes 18 of the magnetic material block 11, and the other leg portions 17b are inserted into the through holes 19 of the second insulating magnetic material block 12; A substrate 15, a plurality of individual electrodes 20 provided on one main surface of the dielectric substrate 15, and a portion provided on the other main surface of the dielectric substrate 15 so as to have a portion facing the plurality of individual electrodes 20. and a metal plate 13a, 13b or 13 having a common terminal 28, and the metal plate 13a, 13b or 13 has the first and second insulating magnetic elements. The metal plates 13a, 13b or 1 are disposed between the body blocks 11 and 12.
3, the common terminal 28 and the inverted U-shaped conducting wire 17
The tip portions of the pair of legs 17a, 17b are connected to the first and second insulating magnetic blocks 11, 1.
2 in the same direction, and the capacitor block 16 is connected to the main portion of the first and second insulating magnetic blocks 11 and 12 on the side where the top portion 17C of the inverted U-shaped conducting wire 17 is arranged. on the surface or the first and second insulating magnetic blocks 11,
The plurality of individual electrodes 20 of the capacitor block 16 are respectively connected to the top portions 17c of the plurality of inverted U-shaped conducting wires 17, and the common electrodes of the capacitor block 16 Reference numeral 21 relates to a noise filter device characterized in that it is connected to the metal plate 13a, 13b or 13.

[Function] When divided into the first and second insulating magnetic blocks 11 and 12 as in the above idea, interference between the pair of legs 17a and 17b of the inverted U-shaped conducting wire 17 is reduced; The noise removal effect is improved. In other words, an inverted U
Noise absorbed by the magnetic material surrounding one leg 17a of the character-shaped conducting wire 17 is prevented from entering the other leg 17b, and the noise removal effect is enhanced. The metal plate 13a, 13b or 13 is not only used for electrical connection, but also functions as a spacer between the first and second insulating magnetically suppressive blocks 11, 12 and contributes to magnetic separation.

[First Embodiment] A T-type LC noise filter device (filter array) according to the first embodiment of the present invention is shown in FIGS. 1 to 5.
This will be explained with reference to the figures. This noise filter device includes a capacitor including first and second ferrite blocks 11 and 12 made of insulating magnetic material, first and second ground plates 13a and 13b, a pedestal 14, and a dielectric substrate 15. It consists of a block 16 and a plurality of inverted U-shaped conducting wires 17.

Each ferrite block 11, 12 is made of rectangular parallelepiped ferrite and has a plurality of through holes 18, 19 extending from one main surface to the other main surface. In addition,
These ferrite blocks 11 and 12 are made by adding a binder to a Ni-Zn ferrite material, granulating it, dry molding it, and, taking into account shrinkage due to firing, correspond to the pair of legs 17a and 17b of the inverted U-shaped conducting wire 17. It is fired after forming through holes 18 and 19 by drilling at the positions, has a magnetic permeability of about 1000, and has dimensions of 30 mm in length, 4 mm in width, and 7 mm in thickness.

The dielectric substrate 15 has a length of 30 mm, a width of 3 mm, and a thickness.
It consists of a 0.85 mm strontium titanate dielectric ceramic substrate, with individual electrodes 20 on one main surface (top surface) corresponding to the inverted U-shaped conductor 17, and a common electrode on the other main surface (bottom surface). (ground electrode) 21. The individual electrodes 20 and the common electrode 21 are formed by screen printing and firing silver (Ag) paste, and are arranged so as to have portions facing each other. The dielectric constant of the dielectric substrate 15 is approximately 30,000, and each individual electrode 2
0 and the common electrode 21 is approximately 50 pF.

First and second earth plates (ground connection members)
13a, 13b and the pedestal 14 are metal plates such as brass plated with solder. The first and second ground plates 13a and 13b are arranged between the first and second ferrite blocks 11 and 12, and the pedestal 14 is arranged between the first and second ferrite blocks 1.
1 and 12. The pedestal 14 is provided with a through hole 22 corresponding to each conducting wire 17, into which each leg portion 17a, 17b of the inverted U-shaped conducting wire 17 is inserted. Note that the through hole 22 is connected to the leg portion 17.
It is formed sufficiently large so as not to come into contact with a and 17b.

In order to integrate the first and second ground plates 13a and 13b and the pedestal 14, grooves 23a and 23 are formed in the first and second ground plates 13 as shown in FIG.
b is provided, and the pedestal 14 is also provided with a groove 24. Grooves 23a, 23b, 24 are connected to each ground plate 13.
a, 13b and the pedestal 14 in the longitudinal direction, the first and second grounding plates 13
The extended portions of the grooves 23a, 23b of the base plates 13a, 13b are placed in the grooves 24 of the pedestal 14, and the extended portions of the grooves 24 of the pedestal 14 are placed in the grooves 23a, 23 of the ground plates 13a, 13b.
By arranging it at point b, an assembly having a cruciform cross-sectional shape as shown in FIG. 2 is obtained.

When assembling this noise filter device,
The first and second parts have bent parts 25a and 25b.
The earth plates 13a and 13b are combined so that they have a T-shaped cross section, and these and the pedestal 14 are connected to the groove 23.
Connect using a, 23b, and 24. Next, the upper portions of the ground plates 13a and 13b, that is, the bent portions 25
The common electrode 21 of the dielectric substrate 15 is placed on a and 25b.
are conductively coupled by solder 26 based on solder reflow.

Next, the first and second ground plates 13a, 13b
The first and second ferrite blocks 11 and 12 are arranged so as to sandwich them, and the vertical positioning of the first and second ferrite blocks 11 and 12 is achieved by the pedestal 14 and the bent portions 25a and 25b. do. Note that the first ferrite block 11
The first and second ferrite blocks 11,
12. Next, one leg 17a of the inverted U-shaped conducting wire 17 is attached to the first ferrite block 1.
The other leg 17b is inserted into the through hole 20 of the second ferrite block 12 and the through hole 22 of the pedestal 14, and the top 17c is inserted into the individual electrode 20. Bring it into contact.
Thereafter, each individual electrode 20 is conductively coupled to the top 17c of the inverted U-shaped conducting wire 17 by solder 27.

When installing the completed noise filter device on the circuit board, remove the inverted U-shaped conductor 1 that protrudes downward.
7 and the ground terminals 28 of the first and second ground plates 13a, 13b are inserted into the through holes of the circuit board and connected to the wiring conductor layer of the signal line and the ground wiring conductor layer of the circuit board. do. Since each conducting wire 17 is connected in series to each signal line, two inductance elements are connected in series to each signal line, and one capacitor is connected between the signal line and ground. A T-type noise filter circuit is obtained.

In order to investigate the noise absorption effect of this noise filter device, we connected the noise filter device to the connection board of the interface cable of a personal computer, kept the other end of this cable open, and
The amount of radiated noise from 30MHz to 240MHz was measured using the 3m method and at an open site in accordance with the regulations of the Japanese Commission. Furthermore, since it is an open site, broadcast waves etc. entering from outside were removed.

Figure 13 shows the noise measurement results.
A shows the noise level emitted from the computer interface cable when no noise filter device is connected, and B shows the noise level emitted from the interface cable when the conventional noise filter device shown in Fig. 14 is connected. The noise level is shown, and C shows the radiation noise level when the noise filter device of the first embodiment is connected. As is clear from the comparison of Fig. 13A, B, and C, in the case of the conventional noise filter device, 15~
It has a noise reduction effect of about 20dBμV/m, and is the first
In the case of the noise filter device in the example of
It has a noise reduction effect of about 30dBμV/m.

In the noise filter device of the first embodiment, the pair of legs 17a, 17 of the inverted U-shaped conducting wire 17
b is not inserted through the through holes of the common ferrite block and the common dielectric substrate, but is inserted through the through holes 18 and 19 of the divided first and second ferrite blocks 11 and 12, and First and second ground plates 13a and 13b are arranged between the second ferrite blocks 11 and 12. As a result, one leg 1 of the inverted U-shaped conducting wire 17
Mutual interference of noise absorbed by the ferrite surrounding 7a affecting the other leg 17b is reduced,
The noise reduction effect is improved.

Further, in this embodiment, the first and second earth plates 1
3a and 13b connect the common electrode 21 to the ground wiring conductor layer of the circuit board through the shortest distance.
Contributes to noise reduction.

[Second Example] Next, FIGS. 6 to 10 showing a second example will be described. However, in Figures 6 to 10,
Components common to those in FIGS. 5 to 5 are designated by the same reference numerals, and description thereof will be omitted.

In this embodiment, the dielectric substrate 15 is the first and second
The ferrite blocks 11 and 12 are arranged between each other. In addition, the top 17 of the inverted U-shaped conducting wire 17
A common electrode 21 is conductively coupled with solder 26 to the ground plate 13 which is formed so as not to come into contact with the ground plate 13.
The ground plate 13 and the pedestal 14 are integrated using respective grooves 23 and 24 shown in FIG.

The individual electrodes 20 are also provided on the side surface of the dielectric substrate 15 as shown in FIG.
It is conductively coupled to the top portion 17c of the character-shaped conducting wire 17. Even with this configuration, the same effects as in the first embodiment can be obtained.

[Third Example] Next, a noise filter device according to a third example shown in FIGS. 11 and 12 will be described. However, the first
1 and 12, parts common to those in FIGS. 1 to 10 are designated by the same reference numerals and their explanations will be omitted. The noise filter device of this third embodiment has a case 29 added to the noise filter device of the second embodiment. The case 29 is made of synthetic resin that can be slightly elastically deformed, and the pedestal 14
A hole 31 for fitting the protrusion 30 provided in the
has. The tip of the protrusion 30 is rounded, so when the case 29 is fitted, the opposite side of the case 29 opens slightly and the protrusion 30 enters the hole 31, and then the opposite side of the case 29 returns to its original shape, allowing for assembly. is completed. As a result, a noise filter device in which each part is more firmly integrated can be obtained.
In addition, as shown by the chain line in Fig. 7, the inverted U-shaped conductor 1
A noise filter device in which the top portion 17c of the noise filter 7 is electrically insulated by the case 29 is obtained.

[Modifications] The present invention is not limited to the above-described embodiments, but can be modified as follows, for example.

(1) Two dielectric substrates each having an individual electrode and a common electrode are arranged above the first and second grounding plates 13a and 13b, and the two dielectric substrates are placed between the signal line and the ground as shown in Fig. 15. Two capacitors may be provided. Further, a dielectric substrate having individual electrodes and a common electrode is arranged on the left side of the grounding plate 13 in FIG.
7c to form a circuit configuration equivalent to that shown in FIG.

(2) The pedestal 14 may be made of synthetic resin.

(3) A plurality of noise filter devices shown in FIG. 1 or FIG. 7 may be arranged side by side to form a structure in which they are integrated.

[Effect of the idea] The present invention has the following effects.

(b) Since the magnetic material is divided into the first and second insulated magnetism inhibiting material blocks 11 and 12, a magnetic circuit based on one leg 17a of the inverted U-shaped conducting wire 17 and a magnetic circuit based on the other leg 17b are connected. It is possible to prevent mutual interference between the based magnetic circuits and obtain a good noise removal effect.

(b) By arranging the metal plates 13a, 13b or 13 between the first and second insulating magnetic blocks 11 and 12, the capacitor block 1
Not only can the electrical connection of the common electrode 21 at 6 be easily achieved, but also the metal plate 1
3a, 13b or 13 function as a spacer between the first and second insulating magnetic blocks 11, 12, and good magnetic separation between them is achieved.

(c) A plurality of LC filters can be easily obtained by combining the first and second insulating magnetic blocks 11 and 12 and the dielectric substrate 15.

[Brief explanation of the drawing]

FIG. 1 is a perspective view showing the noise filter device of the first embodiment, FIG. 2 is an enlarged vertical sectional view of the noise filter device of FIG. 1, and FIG. 3 is an individual electrode on one main surface of the dielectric substrate. FIG. 4 is a bottom view showing the common electrode on the other main surface of the dielectric substrate, FIG. 5 is a perspective view showing the first and second ground plates and the pedestal,
6 is an exploded perspective view showing the noise filter device of the second embodiment, FIG. 7 is an enlarged vertical sectional view of the noise filter device of FIG. 6, and FIG. 8 is the dielectric substrate and individual electrodes of FIG. 6. , FIG. 9 is a diagram showing the dielectric substrate and common electrode in FIG. 6, FIG. 10 is a perspective view showing the ground plate and pedestal in FIG. 6, and FIG. 11 is a noise diagram in the third embodiment. FIG. 12 is a perspective view showing the state of the noise filter device of the third embodiment before the case is attached, FIG. 13 is a perspective view of the noise filter device of the third embodiment after the case is attached, and FIG. 13 is the first embodiment. FIG. 14 is a perspective view of the conventional noise filter device, and FIG. 15 is an equivalent circuit diagram of the conventional noise filter device. 11...first ferrite block, 12...
Second ferrite block, 13, 13a, 13
b...Earth plate, 14...Pedestal, 15...Dielectric substrate, 16...Capacitor block, 17...Inverted U-shaped conducting wire, 18, 19...Through hole, 20...Individual electrode, 21... Common electrode, 26, 27...solder.

Claims (1)

[Claims for Utility Model Registration] A first insulating magnetic block 11 in which a plurality of through holes 18 are arranged in an array; a second insulating magnetic block 12 in which a plurality of through holes 19 corresponding to the plurality of through holes 18 of the first insulating magnetic block 11 are arranged in an aligned state; a pair of legs 17a and 17b; It is formed into a substantially U-shape having a top portion 17c, and one leg portion 17a is connected to the through hole 18 of the first insulating magnetic block 11.
A plurality of inverted U-shaped conducting wires 17 are inserted into the through hole 19 of the second insulating magnetic block 12, and the other leg portion 17b is inserted into the through hole 19 of the second insulating magnetic block 12; A capacitor block consisting of a plurality of individual electrodes 20 provided on one main surface and a common electrode 21 provided on the other main surface of the dielectric substrate 15 so as to have a portion facing the plurality of individual electrodes 20. 16, and a metal plate 13a, 13b or 13 having a common terminal 28, and the metal plate 13a, 13b or 13 is provided between the first and second insulating magnetic blocks 11, 12. The common terminal 28 of the metal plate 13a, 13b or 13 and the tip end portions of the pair of legs 17a, 17b of the inverted U-shaped conducting wire 17 are connected to the first and second insulating magnetic blocks 11. , 12 in the same direction, and the capacitor block 16 is connected to the inverted U of the first and second insulating magnetic blocks 11 and 12.
It is arranged on the main surface of the side where the top part 17C of the character-shaped conducting wire 17 is arranged or between the first and second insulating magnetic blocks 11 and 12, and the plurality of capacitor blocks 16 The individual electrodes 20 are respectively connected to the top portions 17c of the plurality of inverted U-shaped conducting wires 17, and the common electrodes 20 of the capacitor block 16
A noise filter device 1 is connected to the metal plate 13a, 13b or 13.