JP2000315930A - filter - Google Patents

Abstract

(57) [Problem] To improve the function of a common mode choke used for a filter as a normal mode filter. SOLUTION: The filter according to the present invention comprises a first or second capacitor 1 or 3 connected to an input or output side of a common mode choke 2 having two magnetically coupled windings. Two connection lines 60 and 61 for electrically connecting any one of the second capacitors 3 and the common mode choke 2 are wired so as to three-dimensionally intersect.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a filter for suppressing noise using a common mode choke having two magnetically coupled windings.

[0002]

2. Description of the Related Art Usually, a filter for suppressing noise generated on an AC line or a DC line includes an inductance component inserted in series with these lines,
That is, it is composed of a choke coil and a capacitance component, that is, a capacitor, connected in parallel between two lines on the input side or the output side. The filter is a low-pass filter that removes high-frequency components. This filter is used particularly in a power supply device using a commercial AC power supply as an input source so that noise generated in the power supply device does not propagate through an input AC line and adversely affect other electronic devices.

FIG. 5 is a circuit diagram showing a conventional filter used in a power supply device. As shown in FIG. 5, the conventional filter includes a common mode choke 2 and first and second capacitors 1 and 3 connected to an input side and an output side thereof. The conventional filter configured as described above is often disposed on an input AC line of a power supply device. As a technique relating to such a filter wiring pattern, there is a technique disclosed in Japanese Patent Application Laid-Open No. 9-266678.

FIG. 6 is a layout diagram showing a wiring pattern of a filter in the power supply device disclosed in Japanese Patent Application Laid-Open No. 9-266678. As shown in FIG. 6, a pattern PA having one polarity, a pattern PB having the other polarity, a DC positive electrode pattern PC, and a DC negative electrode pattern PD of the commercial AC power supply e are formed on the substrate 5. As shown in FIG. 1, in the patterns PA and PB having different polarities, each is linearly arranged so as not to enter. Also, a pattern PA and a pattern PC having the same polarity are used.
The portions overlapping in the longitudinal direction of the substrate 5 are made small between them, and the patterns PB and PD are arranged so as to be away from each other. As described above, since the wiring pattern in the conventional filter is formed, high-frequency short circuit due to stray capacitance is prevented, and noise is reduced.

[0005]

In the conventional filter configured as shown in FIG. 5, the magnetic coupling between the windings of the common mode choke 2 is not 100%, and each line has an independent inductance component. Thus, the common mode choke 2 also functions as a normal mode choke. Therefore, the common mode choke 2 has a function as a normal mode filter together with the first capacitor 1 and the second capacitor 2.

FIG. 7 is an explanatory diagram schematically showing a wiring pattern of the conventional filter shown in FIG. In the wiring pattern shown in FIG. 7, a first high-frequency current loop formed by an input device 11 and a first capacitor 1 connected to the input device 11, an output device 12 and an output device 12 Has a second high-frequency current loop formed by a second capacitor 3 connected to the second capacitor. In the case of this configuration, since the first high-frequency current loop and the second high-frequency current loop are magnetically coupled, the high-frequency current input to the filter from the input device 11 is supplied to the common mode choke 2.
Is transmitted around. Therefore, in the case of the wiring pattern shown in FIG. 7, the performance as a normal mode filter deteriorates. An object of the present invention is to improve the function as a normal mode filter in a filter having a common mode choke.

[0007]

In order to achieve the above object, a filter according to the present invention comprises two magnetically coupled filters.
A common mode choke having two windings, a first capacitor connected to an input side of the common mode choke, a second capacitor connected to an output side of the common mode choke, Two input-side connection lines electrically connecting both ends and two input-side terminals of the common mode choke so as to three-dimensionally cross each other; two output-side terminals of the common mode choke; And two output-side connection lines electrically connected to both ends of the capacitor and arranged substantially in parallel.

With the above configuration, the characteristics of the normal mode filter at a high frequency can be improved. This is because the direction of transmission of the magnetic coupling between the first high-frequency current loop formed on the input side and the second high-frequency current loop formed on the output side is reversed, and the direction of the normal mode high-frequency current that is to be blocked by the filter. It is considered that the transmission direction of the high-frequency current by the magnetic coupling is reversed.

Further, in the filter of the present invention configured as described above, the common mode choke, the first capacitor, and the second capacitor are mounted on a substrate, and the input side connection lines are provided on both sides of the substrate. It can be constituted by the formed wiring pattern. Further, in the filter of the present invention configured as described above, the common mode choke, the first capacitor, and the second capacitor are mounted on a substrate, and the input side connection line is formed on one surface of the substrate. And a jumper wire provided on the other surface of the substrate.

According to another aspect of the present invention, there is provided a filter comprising: a common mode choke having two windings magnetically coupled to each other; a first capacitor connected to an input side of the common mode choke; A second capacitor connected to the output side, and a second capacitor electrically connected between both ends of the first capacitor and two input terminals of the common mode choke and arranged substantially in parallel.
And two output-side connection lines that electrically connect two output-side terminals of the common mode choke and both ends of the second capacitor so as to three-dimensionally cross each other. I do.

With the above configuration, the characteristics of the normal mode filter at high frequencies can be improved. This is because the direction of transmission of the magnetic coupling between the first high-frequency current loop formed on the input side and the second high-frequency current loop formed on the output side is reversed, and the direction of the normal mode high-frequency current that is to be blocked by the filter. It is considered that the transmission direction of the high-frequency current by the magnetic coupling is reversed.

In the filter of the present invention configured as described above, the common mode choke, the first capacitor, and the second capacitor are mounted on a board, and the output-side connection lines are provided on both sides of the board. It can be constituted by the formed wiring pattern. Further, in the filter of the present invention configured as described above, the common mode choke, the first capacitor, and the second capacitor are mounted on a substrate, and the output-side connection line is formed on one surface of the substrate. And a jumper wire provided on the other surface of the substrate.

[0013]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the filter according to the present invention will be described below with reference to the accompanying drawings.

Embodiment 1 FIG. 1 shows Embodiment 1 according to the present invention.
FIG. 6 is a circuit diagram showing a wiring pattern in the filter of FIG.
In FIG. 1, a first capacitor 1 is connected to an input side of a common mode choke 2 having two magnetically coupled windings, and a second capacitor 3 is connected to an output side.
Is connected. As shown in FIG. 1, in the filter of the first embodiment, two connection lines connecting the first capacitor 1 and the common mode choke 2 are configured to three-dimensionally intersect. Also, common mode choke 2
The two connection lines connecting the second capacitor 1 and the second capacitor 1 are arranged substantially in parallel.

FIG. 2 shows an example in which a wiring pattern in the filter of the first embodiment shown in FIG. 1 is embodied. The substrate 50 shown in FIG. 2 has wiring patterns formed on both surfaces thereof. In FIG. 2, a first capacitor 1, a common mode choke 2, and a second capacitor 3 are mounted on a surface of a substrate 50, and a wiring pattern indicated by oblique lines is formed on this surface.

On the other hand, a wiring pattern indicated by a broken line is formed on the back surface of the substrate 50. The connection line 61 of the wiring pattern formed on the back surface of the substrate 50 electrically connects the first capacitor 1 and the common mode choke 2.
As shown in FIG. 2, in the filter of the first embodiment, the connection line 60 that electrically connects the first capacitor 1 and the common mode choke 2 in the wiring pattern formed on the surface of the substrate 50 Are formed so as to three-dimensionally intersect the line 61 of the wiring pattern formed on the substrate 50 with the substrate 50 interposed therebetween. On the other hand, two connection lines 62 and 63 for electrically connecting the common mode choke 2 and the second capacitor 3 in the wiring pattern on the surface of the substrate 50.
Are arranged substantially in parallel. As described above, in the filter according to the first embodiment, the two connection lines that electrically connect the first capacitor 1 on the input side and the common mode choke 2 are three-dimensionally interposed across the double-sided wiring board. It is configured to be.

FIG. 3 is a graph comparing the attenuation characteristics in the normal mode between the filter according to the first embodiment of the present invention and the filter having the conventional configuration. The same components as the first capacitor 1, the common mode choke 2, and the second capacitor 3 were used for the filter of the first embodiment and the conventional filter used in the attenuation characteristic comparison experiment of FIG.
Specifically, a capacitor (type: ECQE2A104MW) manufactured by Matsushita Electric Industrial Co., Ltd. having a capacitance of 0.1 μF and having a capacitance of 0.1 μF is used as the first capacitor 1 and the second capacitor 3. A 3.9 mH common mode choke (model: ELF18D290R) manufactured by Matsushita Electronic Components Co., Ltd. was used. The filter of Example 1 used in the comparative experiment and the conventional filter have different wiring patterns. As is clear from the graph of FIG. 3, a difference of up to 20 dB between the filter of the first embodiment and the conventional filter is observed at about 500 kHz in the attenuation characteristic. Therefore, by using the filter of the first embodiment according to the present invention, it is possible to greatly attenuate at a specific frequency as compared with the conventional configuration, and the filter of the first embodiment is used as a normal mode filter for a specific high frequency. It was found that the characteristics were greatly improved.

In the first embodiment, the two connection lines connecting the first capacitor 1 on the input side and the common mode choke 2 are three-dimensionally crossed. However, the same effect as in the first embodiment can be obtained with a configuration in which two connection lines connecting the second capacitor 3 on the output side and the common mode choke 2 are three-dimensionally crossed.

FIG. 4 is a plan view showing a wiring pattern in another embodiment of the filter according to the present invention. In the filter shown in FIG. 4, the substrate 51 is a single-sided wiring board,
The wiring pattern is formed only on the back surface of the substrate. In FIG. 4, the wiring pattern formed on the back surface of the substrate 51 is indicated by a broken line. On the other hand, the components of the first capacitor 1, the common mode choke 2, and the second capacitor 3 are mounted on the surface of the substrate 51. The first capacitor 1, common mode choke 2, and second capacitor 3 in FIG. 4 have the same functions and configurations as the components shown in FIG.

As shown in FIG. 4, on the surface of the substrate 51, the first capacitor 1 on the input side and the common mode choke 2 are electrically connected by a jumper wire 4. A connection line 70 for electrically connecting the first capacitor 1 of the wiring pattern and the common mode choke 2 is arranged so as to face the jumper wire 4 with the substrate 51 interposed therebetween. On the other hand, two connection lines 71 and 72 for electrically connecting the common mode choke 2 and the second capacitor 3 in the wiring pattern on the back surface of the substrate 51 are arranged substantially in parallel.

Using the filter shown in FIG. 4, the inventor conducted an experiment similar to the above-described comparative experiment of the attenuation characteristics shown in FIG. The experimental result was similar to the graph shown in FIG. Therefore, the filter of the present invention can be made conventional by using a double-sided wiring board or a single-sided wiring board as a substrate, by three-dimensionally intersecting the connection lines on the input or output side of the common mode choke 2. Compared to this, it is possible to greatly attenuate a specific frequency, and according to the filter of the present invention, it is possible to greatly improve the characteristics as a normal mode filter at a high frequency.

[0022]

As is apparent from the detailed description of the embodiments, the present invention has the following effects.
According to the present invention, the common mode choke and the first and second
By changing the wiring pattern of the filter composed of the capacitors described above, it becomes possible to greatly improve the attenuation characteristics as a normal mode filter, without changing the components of the conventional filter or increasing the manufacturing cost. The noise suppression function can be improved.

[Brief description of the drawings]

FIG. 1 is a circuit diagram showing a wiring pattern in a filter according to a first embodiment of the present invention.

FIG. 2 is a plan view showing a wiring pattern in which the filter of Example 1 is configured using a double-sided wiring board.

FIG. 3 is a graph showing experimental results obtained by measuring normal mode attenuation characteristics of a filter according to the present invention and a filter according to a conventional configuration.

FIG. 4 is a plan view showing another embodiment of the filter according to the present invention, showing a wiring pattern formed using a single-sided wiring board.

FIG. 5 is a circuit diagram of a conventional filter.

FIG. 6 is a plan view showing a wiring pattern of a conventional filter.

FIG. 7 is an explanatory diagram schematically showing a wiring pattern of a conventional filter.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 1st capacitor 2 Common mode choke 3 2nd capacitor 50 Substrate 60 Connection line 61 Connection line 62 Connection line 63 Connection line

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 5G066 EA01 5H740 NN02 PP03 5J024 AA01 BA14 CA06 DA01 DA26 DA32 EA09

Claims (6)

[Claims] 1. A common mode choke having two windings magnetically coupled to each other, a first capacitor connected to an input side of the common mode choke, and a second capacitor connected to an output side of the common mode choke. Two input-side connection lines for electrically connecting both ends of the first capacitor and two input-side terminals of the common mode choke so as to three-dimensionally cross each other, and two outputs of the common mode choke A filter comprising: two output-side connection lines that are electrically connected between a side terminal and both ends of the second capacitor and disposed substantially in parallel. 2. The method according to claim 1, wherein the common mode choke, the first capacitor, and the second capacitor are mounted on a substrate, and the input-side connection lines are formed by wiring patterns formed on both surfaces of the substrate. The filter described. 3. The wiring pattern in which the common mode choke, the first capacitor, and the second capacitor are mounted on a substrate, and the input side connection line is formed on one surface of the substrate and the other of the substrate. The filter according to claim 1, wherein the filter is configured by a jumper wire provided on the surface. 4. A common mode choke having two windings magnetically coupled to each other, a first capacitor connected to an input side of the common mode choke, and a second capacitor connected to an output side of the common mode choke. Two input-side connection lines electrically connected between both ends of the first capacitor and two input-side terminals of the common mode choke and arranged substantially in parallel; A filter comprising: two output-side terminals and two output-side connection lines that electrically connect two output terminals and two ends of the second capacitor so as to three-dimensionally cross each other. 5. The circuit according to claim 4, wherein the common mode choke, the first capacitor, and the second capacitor are mounted on a substrate, and the output-side connection line is formed by a wiring pattern formed on both surfaces of the substrate. The filter described. 6. A wiring pattern in which the common mode choke, the first capacitor, and the second capacitor are mounted on a substrate, and the output-side connection line is formed on one surface of the substrate and the other side of the substrate. The filter according to claim 4, wherein the filter is configured by a jumper wire provided on the surface.