JPH0621211Y2 - Noise filter device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial application] The present invention relates to a noise filter device including a large number of inductances.

[Prior Art] In digital signal processing circuits of various electronic devices that handle digital signals, the input conductors are easily affected by external noise, and erroneous input due to external noise (noise) may be directly processed as a correct input signal. There is. In addition, noise may be emitted from the digital signal processing circuit to the outside.

In order to eliminate the influence of such noise, it is known to construct an inductance element by passing the input and output conductors of a signal processing circuit through ferrite beads (cylindrical ferrite).

Further, as shown in FIG. 1, a plurality of pairs of through holes 2 are provided in the ferrite block 1 and the inverted U-shaped conducting wire 3 is inserted to form an assembly of a plurality of inductance elements (multiple inductance elements). It is also known.

[Problems to be solved by the invention] By the way, in the case of forming an inductance element using the former ferrite beads, it is necessary to prepare a large number of ferrite beads for a large number of signal lines and insert conductor wires into each of them. I have to. Therefore, this inductance element has the drawback of being cumbersome to assemble.

On the other hand, the latter multiple inductance element has a feature that it is easy to assemble and can be downsized, but
Since one leg portion 3a and the other leg portion 3b of the inverted U-shaped conductor 3 face each other via the common ferrite block 1 and also face each other outside the ferrite block 1, one leg portion There is a drawback in that noise absorbed by the ferrite block surrounding the coil interferes with the other leg and a mutual interference phenomenon occurs, and noise cannot be satisfactorily removed.

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] The present invention for achieving the above object includes a first insulating magnetic body block in which a plurality of through holes are arranged in an aligned state, and the first insulating magnetic body. A second insulating magnetic body block juxtaposed to the body block and having a plurality of through holes corresponding to the plurality of through holes of the first insulating magnetic body block arranged in alignment; A plurality of substantially inverted U-shaped conductive wires whose parts are inserted into the through holes of the first insulating magnetic body block and the other leg parts are inserted into the through holes of the second insulating magnetic body block. , A ground connection plate arranged between the facing surfaces of the first and second insulating magnetic material blocks so as not to come into contact with the conducting wire.

[Operation and Effect of the Invention] In the noise filter device of the present invention, one leg and the other leg of the inverted U-shaped conductor are inserted into the first and second insulating magnetic material blocks, and A ground connection conductor (earth plate) between the first and second insulating magnetic material blocks
Are arranged, the interference between the legs is reduced, and a good noise reduction effect can be obtained.

[First Embodiment] A noise filter device (filter array) according to a first embodiment of the present invention will be described with reference to Figs.
This noise filter device comprises first and second ferrite blocks 4 and 5 made of an insulating magnetic material and a plurality of inverted U-shaped conductors 6. The first and second ferrite blocks 4,
5 is made of rectangular parallelepiped ferrite and has a plurality of through holes 7 and 8 penetrating from one main surface to the other main surface, respectively. The ferrite blocks 4 and 5 are made of Ni-Zn.
Binder is added with a ferrite ferrite material, granulated, dry-molded, and then the through-holes 7 and 8 are formed by drilling at positions corresponding to the inverted U-shaped conducting wire 6 in consideration of shrinkage due to firing, and then fired. It has a magnetic permeability of about 1000, and has dimensions of 25 mm in length, 3 mm in width, and 7 mm in thickness.

The noise filter device further includes a ground plate 10 and a synthetic resin (ABS resin) insulating pedestal 11. The ground plate 10 is made of a metal plate (bronze plate) solder-plated, and is arranged between the first and second ferrite blocks 4 and 5. The pedestal 11 is arranged so as to cover the lower surfaces of the first and second ferrite blocks 4 and 5, and the conductor 6
It has a through hole 12 for inserting the leg portions 6a and 6b. In order to easily achieve the attachment of the ground plate 10 and the pedestal 11, the groove 13 is provided in the ground plate 10 and the pedestal 1
1 is also provided with a groove 14. Since the grooves 13 and 14 are provided in the longitudinal half of the ground plate and the pedestal 11, the extended portion of the groove 13 of the ground plate 10 is arranged in the groove 14 of the pedestal 11, and the extended portion of the groove 14 of the pedestal 11 is arranged. Is arranged in the groove 13 of the ground plate 10 to obtain an assembly having a cross-shaped cross section.

The ground plate 10 is fixed to the first and second ferrite blocks 4 and 5 with an insulating adhesive 9 as shown in FIG. Since the ground plate 10 is provided with the terminal 15 protruding downward, this is connected to the ground conductor layer of the circuit board.

The first and second ferrite blocks 4 and 5 as the first and second insulating magnetic material blocks are arranged so that the through holes 7 and 8 formed therein face each other, and the pair of leg portions 6a is formed. , 6b and the top portion 6c, one leg portion 6a of the U-shaped conductor 6 is inserted into the through hole 7 of the first ferrite block 4, and the other leg portion 6b is connected to the second ferrite block 5.
Through the through hole 8 and the top 6c is fixed to the upper surfaces of the ferrite blocks 4 and 5 with an adhesive 9.

When the noise filter device having the multiple structure is mounted on the circuit board, the terminals 15 of the ground plate 10 are connected to the ground (ground) conductor layer of the circuit board, and each of the ferrite blocks 4 and 5 protrudes from the lower surface. Legs 6a, 6b
Is inserted into the through hole of the circuit board and connected to the wiring conductor layer of the signal line of the circuit board. Since each conductor 6 is connected in series to each signal line, a circuit in which two inductance elements are connected in series to each signal line can be obtained.

In order to investigate the noise absorption effect of this noise filter device, a noise filter layer is connected to the connection board of the interface cable of the personal computer, and the other end of this cable is kept open, and the FCC (Federal Commun
30MHz ~ 240MHz according to regulations of the ication Commission)
The amount of radiation noise of was measured at an open site using the 3 m method. In addition, since it is an open site, we have removed broadcast waves that entered from the outside.

FIG. 2 shows the result of noise measurement, (A) shows the level of noise radiated from the interface cable of the computer when the noise filter device is not connected, and (B) shows the conventional one shown in FIG. The radiation noise level from the interface cable when the noise filter device of No. 1 is connected is shown. (C) shows the case where the noise filter device of the comparative example of the configuration in which the earth plate 10 is omitted from the noise filter device of the embodiment is connected. The radiation noise level is shown, and (D) shows the radiation noise level when the noise filter device of the first embodiment is connected. Figure 2 (A)
As is clear from the comparison between (B) and (C), the conventional noise filter device has a noise reduction effect of about 5 to 10 dBμV / m, and the noise filter device of the comparative example has a noise reduction effect of 5 to 15 dBμV / m. There is a noise reduction effect of about m.

On the other hand, the radiation noise level of the noise filter device of the first embodiment is as shown in FIG.
A noise reduction effect of about 20 dBμV / m was obtained. This effect is divided into the first and second ferrite blocks 4 and 5, and the ground plate 10 is arranged between them, so that one and the other leg portions 6 of the inverted U-shaped conductor 6 are provided.
This is obtained because the mutual interference of a and 6b is reduced.

[Second Embodiment] Next, a noise filter device according to a second embodiment shown in FIGS. 7 to 9 will be described. However, in FIG. 7 to FIG. 9, the same parts as those in FIG. 1 to FIG. 6 are designated by the same reference numerals and the description thereof will be omitted.

In the second embodiment, a lid 16 made of synthetic resin (ABS resin) that is slightly elastically deformed is provided, and a protrusion 18 for inserting into the fitting hole 17 of the lid 16 is provided on the pedestal 11a. . The pedestal 11a of this embodiment is made of bronze metal plated with solder, and is integrally formed with the ground plate portion 10.
a. Since the tip of the protrusion 18 has a rounded shape,
When the lid 16 is fitted, the opposite side surface of the lid 16 is slightly opened and the projection 18 is inserted into the hole 17, and then the opposite side surface of the lid 16 returns to its original state, and the assembly is completed.

In the second embodiment, the pedestal 11a and the lid 16 are used to form the first and second ferrite blocks 4 and 5 and the top portion 6 of the conductive wire 6.
Since c is surrounded, electrical insulation of the top 6c of the conductor 6
Protection of the first and second ferrite blocks 4, 5 is achieved. Further, it becomes possible to integrate the respective parts without depending on the adhesive material. Further, since the pedestal 11a is made of metal and is grounded by the grounding terminal 15a, it is possible to obtain the effect of separating the leg portions 6a, 6b of the conductive wire 6 protruding below the first and second ferrite blocks 4, 5. it can.

[Modification] The present invention is not limited to the above-described embodiments, and the following modifications are possible, for example.

(1) As shown in FIG. 10, a protrusion 18 may be provided at the intermediate portion of the ground plate 10.

(2) As shown in FIG. 11, the ground plate 10 may be provided with no protrusion and the entire lower portion of the ground plate 10 may be inserted into the groove of the circuit board. In this way, the leg portions 6a and 6b of the conductor wire 6 protruding below the first and second ferrite blocks 4 and 5 are sufficiently separated from each other.

(3) A plurality of noise filter devices shown in FIG. 3 may be arranged side by side, and these may be integrated.

(4) It is also applicable to the case where capacitors and the like are arranged above or below the first and second ferrite blocks 4 and 5.

(5) Ground plate portion 10a and pedestal 1 in the second embodiment
1a may be separated, and the pedestal 11a may be made of synthetic resin as in the first embodiment.

[Brief description of drawings]

FIG. 1 is a perspective view showing a conventional noise filter device, FIG. 2 is a diagram showing the noise absorption effect of the noise filter devices of the conventional example, the comparative example and the first example, and FIG. 3 is the first example. FIG. 4 is an enlarged vertical sectional view of the noise filter device of FIG. 3, FIG. 5 is an exploded perspective view of the noise filter device of FIG. 3, and FIG. FIG. 7 is a perspective view showing a ground plate and a pedestal of the noise filter device, FIG. 7 is a perspective view showing the noise filter of the second embodiment, FIG. 8 is an exploded perspective view of the noise filter device of FIG. 7, and FIG. Is an enlarged vertical cross-sectional view of the noise filter device of FIG. 7, FIGS. 10 and 11 are front views showing modified examples of the ground plate, 4 ... First ferrite block, 5 ... Second ferrite block, 6 ... Conductors, 6a, 6b ... Legs, 7, 8 ... Through holes, 10 ... Ground plate.

Claims (1)

[Scope of utility model registration request] 1. A first insulating magnetic body block in which a plurality of through holes are arranged in an array, and a first insulating magnetic body which is juxtaposed with the first insulating magnetic body block. A second insulating magnetic body block in which a plurality of through holes corresponding to the plurality of through holes of the block are arranged in an aligned state, and one leg is a through hole of the first insulating magnetic body block. A plurality of substantially inverted U-shaped conductors that are inserted and the other leg is inserted into the through hole of the second insulating magnetic body block, and the first and second conductors so as not to contact the conductors. A noise filter device comprising a ground connection plate arranged between opposing surfaces of an insulating magnetic body block.