JPH0786863A - Noise eliminating parts - Google Patents

Abstract

PURPOSE:To provide noise eliminating parts that can eliminate both common and normal mode noises. CONSTITUTION:A pair of circuits have the inductors connected in series, and a capacitor is connected between the inductors of both circuits. Then the ferrite sheets 2 containing the printed patterns of internal electrodes 1 are put on each other in the order of A, B, C and D. A coil is formed by a through hole 3, and a rectangular dielectric 4 formed by means of a PET film 5 is put on the coil so as to match with the rectangular pattern of the sheet D. Then the sheets F, G, H and I are put on the dielectric 4 in the same way. The cover sheets provided on the upper and lower sides of those sheets 2 put on each other. Thus a laminated structure is acquired, and the terminals A1, A2, B1 and B2 of a coil conductor are led out through the side faces of the laminated structure.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a noise removing component for removing common mode noise and normal mode noise.

[0002]

2. Description of the Related Art Noise generated inside an electronic device flows out of the device from an AC line or a DC line, or noise generated outside enters the device.

There are two types of noise, common mode noise and normal mode noise. As the noise removing component for removing the former common mode noise, there is a common mode choke coil, which has a magnetic ferrite core on a resin bobbin. It is common that the magnetic core is attached and the conductor wire wound around the magnetic core is wound, and its appearance and equivalent circuit diagram are shown in FIG.
Shown in (a) and (b). The terminals a1 and a2 are inserted into the power supply secondary side line, and the terminals b1 and b2 are inserted into the ground for use.

As the noise removing component for removing the latter normal mode noise, there is an EMI removing filter, which has two inductors connected in series and one terminal of a capacitor is connected to the connecting line to connect in series. The terminal of the connected inductor and the other terminal of the capacitor constitute a three-terminal component, and its appearance and equivalent circuit diagram are shown in FIG.
Shown in (a) and (b). The a and c terminals are connected in series to the signal line, and the b terminal is inserted into the ground line.
A coil having a and c terminals absorbs noise, and a high frequency component is released to the ground by the electrostatic capacitance component of the capacitor.

[0005]

Among the conventional noise removing parts, there are noise removing parts corresponding to normal mode noise and common mode noise.

For normal mode noise, if an EMI removal filter is used, for example, normal mode noise is removed but common mode noise remains unremoved, and for common mode noise, for example, common If a mode choke coil is used, common mode noise will be removed, but normal mode noise will remain without being removed. Therefore, when trying to remove both noises, there are problems of inconvenience of using two parts and obstacles to downsizing due to an increase in the number of parts.

Therefore, an object of the present invention is to reduce both normal mode noise and common mode noise to 1
It is to provide a noise removal component that can be removed by one component.

[0008]

DISCLOSURE OF THE INVENTION As a result of researches aimed at achieving the above object, the inventors of the present invention have firstly provided a circuit in which inductors are connected in series in a ceramic laminated body in a pair, and A capacitor is connected in between and one end of each inductor is led to the side surface of the laminated body, or
In the same manner, a circuit in which inductors are connected in series in the laminated body and one inductor are provided in a pair, and a capacitor is connected between the inductors of the circuit and one terminal of the other inductor, and the inductor of the circuit is connected. The present invention has been found out that both the common mode noise and the normal mode noise can be removed by a single component by constructing the noise elimination component by deriving both ends of the terminal and the other inductor to the side surface of the laminated body. .

Therefore, the present invention is, firstly, a noise elimination component in which a conductor is formed in a ceramic laminated body, an end of the conductor is led to a side surface of the laminated body, and is connected to an external electrode terminal formed on the side surface. And a circuit in which inductors are connected in series is provided, and a capacitor is connected between the inductors of one circuit of the pair and between the inductors of the other circuit, and one terminal of each inductor is A noise removing component characterized by being led to the side surface of the laminated body;
Secondly, a noise removal component in which a conductor is formed in a ceramic laminate, the end of the conductor is led to a side surface of the laminate, and the inductor is connected in series to an external electrode terminal formed on the side surface. The connected circuit and one inductor are provided in a pair, a capacitor is connected between the inductors of the circuit and one terminal of the other inductor, and both terminals of the inductor of the circuit and the other terminal of the inductor are It is intended to provide a noise removal component, which is characterized in that it is led to the side surface of a laminated body.

[0010]

According to the first aspect of the present invention, a circuit in which inductors are connected in series is provided in a pair, and a capacitor is connected between the inductors of the one circuit and the inductors of the other circuit, and one of the inductors is connected. Since the terminal of is connected to the external electrode provided on the side surface of the laminated body, the common mode noise among the noise that has been riding on the signal line is
It is attenuated and substantially removed by an inductor placed in series between the signal line and ground. In the normal mode noise, the capacitor releases the normal mode noise to the ground, the inductor in the ground attenuates the normal mode noise, and substantially removes the noise.

Further, in the second invention, since one inductor on the ground side of the first invention is removed, the impedance on the ground side is lowered to make it easier for noise to return to the ground, thereby preventing noise radiation. Has the effect of

[0012]

[Embodiment 1] FIG. 1 is an exploded perspective view of a laminated body manufactured in this embodiment, FIG. 3 is a perspective view showing an appearance of a manufactured noise removing component, FIG. 4 is its equivalent circuit diagram, and FIG. FIG. 7 is a measurement circuit diagram used for the noise elimination test, FIG. 7 is a measurement circuit diagram used for the common mode noise elimination test in which the components of the present invention are incorporated, and FIG. 8 is a measurement circuit diagram used for the normal mode noise elimination test. 9 is a frequency characteristic graph of the harmonics before the noise removal component is inserted, FIG. 10 is a frequency characteristic graph showing the removal effect when the harmonics of FIG. 9 enter the component of the present invention as common mode noise, and FIG. 9 is a frequency characteristic graph showing the removal effect when the harmonics of 9 enters the component of the present invention as normal mode noise,
A description will be given below with reference to these drawings.

(1) A Ni-Zn based magnetic ferrite green sheet was prepared, and a sheet having through holes formed at predetermined positions and a sheet having no through holes were prepared. The size of the green sheet is such that several hundred to one thousand and several hundred noise-removed parts are obtained, and the pattern described below is printed for each of the parts. For ease of understanding, we describe one component.

(2) As shown in FIG. 1, the through hole 3
B, C, D and G on the ferrite sheet 2 on which
The patterns of the conductor 1 corresponding to H and I were printed with a conductive paste such as Ag.

(3) Further, the pattern of the conductor 1 corresponding to A and F was printed on the sheet having no through hole.

(4) Separately, a dielectric green sheet is formed on a polyethylene terephthalate (PET) film 5, and a pattern of the dielectric 4 corresponding to the rectangular pattern formed inside the coil conductor is left. A PET film is prepared in which only the green sheet is punched out and the other dielectric green sheets are removed.

(5) When these are prepared, first, several sheets on which patterns are not printed and through holes are not formed are stacked to form one cover sheet (not shown), and A, B, C, and The PET film 5 on which the green sheet of the dielectric material 4 is placed after being stacked in the order of the D pattern and temporarily pressure-bonded
Are laminated so that the surface of the dielectric green sheet coincides with the pattern of the same shape located inside the conductor pattern D, and provisionally pressure-bonded, and the PET film is peeled off.

On top of that, F, G, H, and I are stacked in this order, and several sheets on which no pattern is printed and through holes are not formed are stacked on top of that to form the other cover sheet (not shown), which is then crimped. To form a laminated body.

(6) Terminals A1, A2 and B1, B2 of the coil conductor are led out on the side surface of the laminated body. This is fired to form external electrode terminals on the side surfaces of the laminated body and connected to the terminals.

(7) The noise removing component of FIG. 3 thus obtained has an equivalent circuit as shown in FIG.

(8) Using the measurement circuit shown in FIG. 6 as the noise elimination component, in order to see the effect of eliminating common mode noise in which noise of the same phase appears in the signal line and ground,
The measurement circuit was connected as shown in FIG.

The harmonics as shown in the graph of FIG. 9 are input to the A1 and B1 terminals of the noise removing component, output from the A2 and B2 terminals, and passed through this component by the spectroanalyzer at point P of FIG. The result of measuring the waves is shown in the graph of FIG. In the graph of FIG. 10, it is clear that the harmonic level is attenuated as compared with the graph of FIG. 9 and is effective in removing common mode noise.

(9) In order to see the effect of removing noise (normal mode noise) coming only to the signal line, the connection is made as shown in FIG.

The graph of FIG. 11 shows the results of inputting the harmonics shown in FIG. 9 to the A1 terminal and measuring the harmonics output from the A2 terminal with a spectroanalyzer. It is clear that the graph of FIG. 11 has a higher harmonic level than the graph of FIG. 9 and is effective in eliminating normal mode noise.

[0025]

[Embodiment 2] FIG. 2 is an exploded perspective view of a laminated body manufactured in this embodiment, and FIG. 5 is an equivalent circuit diagram of a noise removing component obtained from the laminated body of FIG. And explain.

In Example 1, patterns F and G shown in FIG.
Instead, the same procedure as in Example 1 was carried out except that J and K were used as shown in FIG. 2 to construct a noise removal component having an equivalent circuit diagram shown in FIG.

As a result (not shown) of using the parts in the same manner as in Example 1, the same effect was obtained. Compared with the component of the first embodiment, the component of the present embodiment has one of the inductors on the ground side removed, so that the inductance on the ground side is low, noise easily returns to the ground, and noise radiation is reduced. It has the effect of preventing.

In the present embodiment, the ferrite green sheet laminated on the dielectric disposed inside the coil is
An electrode for obtaining electrostatic capacity is formed on the surface on which the coil conductor is formed, and the surface on which the conductor is not formed is laminated in contact with the dielectric layer, but the electrode for acquiring electrostatic capacitance is formed by the coil conductor. If a pattern is formed on the back surface of the exposed surface and connected to a through hole to lead to the front surface, the counter electrode can be configured without the dielectric material being interposed between the magnetic materials, so that a large capacitance can be obtained. It can be easily analogized.

[0029]

As described above, if the noise removing component of the present invention is used, one noise removing component can be applied to remove noise in both common mode noise and normal mode noise. It is not necessary to use two parts as in the past to remove noise in both modes. Therefore, it is effective in reducing the number of parts and improving miniaturization.

[Brief description of drawings]

FIG. 1 is a laminated exploded perspective view of a laminated body manufactured in one example of the present invention.

FIG. 2 is an exploded perspective view of a laminated body manufactured according to another embodiment of the present invention.

FIG. 3 is a perspective view showing an appearance of a noise removing component of the present invention.

FIG. 4 is an equivalent circuit diagram of a noise removal component obtained from the laminated body of FIG.

5 is an equivalent circuit diagram of a noise removal component obtained from the laminated body of FIG.

FIG. 6 is a measurement circuit diagram used in a noise removal test.

FIG. 7 is a measurement circuit diagram for a common mode noise elimination test in which the component of the present invention is incorporated.

FIG. 8 is a measurement circuit diagram for a normal mode noise reduction test in which the components of the present invention are incorporated.

FIG. 9 is a frequency characteristic graph showing a basic clock for harmonics before the noise removal component is inserted.

FIG. 10 is a frequency characteristic graph showing a common mode noise removal effect of the component of the present invention.

FIG. 11 is a frequency characteristic graph showing a normal mode noise removal effect of the component of the present invention.

FIG. 12 (a) is a perspective view showing the appearance of a common mode choke coil, and FIG. 12 (b) is an equivalent circuit diagram thereof.

13A is a side view showing the appearance of an EMI removal filter, and FIG. 13B is an equivalent circuit diagram thereof.

[Explanation of symbols]

1 Internal Electrode 2 Ferrite Sheet 3 Through Hole 4 Dielectric 5 PET Film A1, A2; B1, B2 Coil Terminal a, b, c; a1, a2; b1, b2 Terminal A, B, C, D, F, G, H, I Internal electrode pattern E Dielectric pattern

Claims (2)

[Claims] 1. A conductor is formed in a ceramic laminate,
A noise elimination component in which an end of the conductor is led to a side surface of the laminated body and connected to an external electrode terminal formed on the side surface, and a circuit in which inductors are connected in series is provided in a pair, and one of the pair of A noise removing component, wherein a capacitor is connected between inductors of a circuit and between inductors of the other circuit, and one end of each inductor is led to a side surface of the laminate. 2. A conductor is formed in the ceramic laminate,
A noise elimination component in which an end of the conductor is led to a side surface of the laminate and is connected to an external electrode terminal formed on the side surface, and a circuit in which inductors are connected in series and one inductor are provided in a pair, A capacitor characterized in that a capacitor is connected between the inductors of the circuit and one terminal of the other inductor, and both terminals of the inductor of the circuit and both terminals of the other inductor are led to the side surface of the laminate. Removal parts.