JP2005218030A - Circuit board provided with line filter circuit - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a circuit board provided with a line filter circuit capable of effectively rejecting noise by reducing stray capacitance that occurs between connection parts of a wiring pattern of the circuit board connected to a choke coil. <P>SOLUTION: A space W1 between connection parts 16a and 16b, and 16c and 16d of respective lines L1 and L2 that connect respective terminals 15a to 15d of the choke coil 11 is defined as ≥5 mm, and the width W of the connection parts 16a to 16d is set to ≤4 mm. A slit 17 whose width W2 is ≥1 mm and whose length S is ≥17 mm is formed among the connection parts 16a to 16d of the respective lines L1 and L2. This can reduce stray capacitance that occurs between the connection parts 16a and 16b and the connection parts 16c and 16d to enhance a noise rejection effect. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a circuit board having a line filter circuit for removing noise, and more particularly to a circuit board having a line filter circuit in which stray capacitance in the line filter circuit is reduced.

  Conventionally, due to the development of various electronic devices, various interferences have occurred from the operation power line of the electronic device while operating these electronic devices, and the interference affects other electronic devices, causing malfunction of the electronic device. It is a factor. In order to prevent these interferences, in Japan, according to the Electrical Appliance and Material Control Law, suppression of the occurrence of the interference and removal of the interference are implemented for each of various electronic devices.

  As a method of removing the interference generated in these power supply lines, for example, as shown in Patent Document 1, a power supply line filter is generally used in the power supply circuit of the electronic equipment. The interference frequency to be removed is removed. That is, as shown in FIG. 3, between the line L1 and the line L2 of the line filter L, capacitors CX1 and CX2 for reducing normal mode noise are connected in parallel. A common mode choke coil L for reducing common mode noise is connected between the capacitors CX1 and CX2. Further, two capacitors Cy1 and Cy2 for reducing common mode noise are connected to the next stage of the capacitor CX2 so as to be in series with each other and in parallel with the capacitor CX2. With the configuration of CX1 and CX2, common mode noise is reduced, and normal mode noise is reduced with capacitors Cy1 and Cy2. The common mode choke coil L and capacitors CX1, CX2, Cy1, and Cy2 are mounted on a circuit board, and a wiring pattern that forms a line filter circuit is formed on the circuit board. The mode choke coils L, CX1, CX2, Cy1, and Cy2 are connected by soldering.

Japanese Patent Laid-Open No. 10-303674

  By the way, the common mode choke coil L includes two sets of coils K1 and K2, and the terminals a to d of the coils K1 and K2 are soldered to connection portions S1 to S4 formed on the lines L1 and L2 of the wiring pattern P, respectively. Conventionally, the interval between the connecting portions S1 and S2 of the lines L1 and L2 and the line connecting portions S3 and S4 formed on the circuit board is set to be extremely narrow. For this reason, stray capacitance is generated between the connection portions S1 and S2 and the connection portions S3 and S4 of the lines L1 and L2, and as a result, as shown in FIG. 4, the connection portions S1 and S2 of the lines L1 and L2, respectively. In addition, since it is equivalent to a state in which the capacitor C is virtually inserted between the connection portions S3 and S4, there is a problem that noise cannot be effectively removed.

  The present invention has been made in view of the above problems, and is a line filter circuit capable of effectively eliminating noise by reducing stray capacitance generated between connection portions of a circuit board wiring pattern connected to a choke coil. It aims at providing a circuit board provided with.

  According to a first aspect of the present invention, there is provided a circuit board including the line filter circuit, wherein a line pattern of the line filter circuit is formed on the circuit board, and the choke that configures the line filter at a connection portion formed on the line of the line filter circuit In a circuit board provided with a line filter to which a coil terminal is connected, the connection portions are formed apart from each other, and a slit is formed between the connection portions.

  According to the configuration of the first aspect, a space is formed by forming a slit between the connecting portions, and the stray capacitance generated between the connecting portions can be escaped from the slit or hardly generated, so that the stray capacitance is reduced.

  The circuit board provided with the line filter circuit according to claim 2 of the present invention is characterized in that in the circuit board provided with the line filter circuit according to claim 1, the interval between the connecting portions is 5 mm or more.

  According to the configuration of the second aspect, the stray capacitance generated between the connection portions is reduced by separating the connection portions by 5 mm or more.

  The circuit board provided with the line filter circuit according to claim 3 of the present invention is the circuit board provided with the line filter circuit according to claim 1 or 2, wherein the slit has a length of 17 mm or more and a width of 1 mm or more. It is characterized by that.

  According to the configuration of the third aspect, the interval between the connection portions can be separated as much as possible, and a slit having a sufficient size to escape the stray capacitance can be formed on the circuit board.

  The circuit board provided with the line filter circuit according to claim 4 of the present invention is the circuit board provided with the line filter circuit according to any one of claims 1 to 3, wherein the width of the connecting portion is 4 mm or less. It is characterized by that.

  According to the configuration of the fourth aspect, the stray capacitance is further reduced by suppressing the surface area of the connection portion to be small.

  According to the circuit board having the line filter circuit of the first aspect of the present invention, the wiring pattern of the line filter circuit is formed on the circuit board, and the line filter is configured at the connection portion formed on the line of the line filter circuit. In the circuit board provided with the line filter to which the terminals of the choke coil to be connected are formed, the connecting portions are formed apart from each other, and a slit is formed between the connecting portions, so that the connecting portion to which the choke coil is connected is formed. It is possible to reduce the stray capacitance generated between them, and also to allow the stray capacitance to escape from the slit and to make it difficult to generate. The removal effect is improved. Moreover, stray capacitance can be reduced simply by forming a slit in the circuit board without adding a countermeasure component for removing stray capacitance, so there is no need to worry about an increase in the number of components and cost reduction. Can contribute.

  According to the circuit board provided with the line filter circuit of claim 2 of the present invention, in the circuit board provided with the line filter circuit according to claim 1, the distance between the connection parts is 5 mm or more. By separating 5 mm or more, stray capacitance generated between the connecting portions can be surely reduced.

  According to a circuit board provided with the line filter circuit of claim 3 of the present invention, in the circuit board provided with the line filter circuit according to claim 1 or 2, the slit has a length of 17 mm or more and a width of 1 mm or more. Therefore, it is possible to form a slit on the circuit board that is large enough to escape the stray capacitance.

  According to the circuit board provided with the line filter circuit according to claim 4 of the present invention, in the circuit board provided with the line filter circuit according to any one of claims 1 to 3, the width of the connecting portion is 4 mm or less. Therefore, by suppressing the surface area of the connection portion to be small, the stray capacitance can be further reduced and the noise removal effect can be enhanced.

  Hereinafter, an embodiment as the best mode for carrying out the present invention will be described with reference to the accompanying drawings. The line fill circuit in this embodiment is substantially the same as the conventional line fill circuit shown in FIG. 3, and the line fill circuit will be described with the same reference numerals assigned to the same parts as those in FIG. As shown in FIG. 4, between the line L1 and line L2 of the line filter L, capacitors CX1 and CX2 for reducing normal mode noise are connected in parallel. A common mode choke coil L for reducing common mode noise is connected between the capacitors CX1 and CX2. Further, two capacitors Cy1 and Cy2 for reducing common mode noise are connected to the next stage of the capacitor CX2 in series with each other and in parallel with the capacitor CX2.

  Reference numeral 10 denotes a circuit board on which a wiring pattern 10A including lines L1 and L2 of the line filter circuit is formed. The choke coil 11 constituting the line filter L includes two sets of windings 13 and 14, and the terminals 15a to 15d of the windings 13 and 14 are formed on the lines L1 and L2. The parts 16a to 16d are connected to each other by soldering. The widths W of the connecting portions 16a to 16d formed on the lines L1 and L2 are set to 4 mm or less, and are formed narrower than the wiring pattern 10A of the lines L1 and L2. That is, the width W of the connecting portions 16a to 16d is set to the minimum width that allows the terminals 15a to 15d of the choke coil 11 to be soldered. Further, the connecting portions 16a and 16b and the connecting portions 16c and 16d in the lines L1 and L2 are formed to be separated from each other, but the interval W1 is determined to some extent by the size of the choke coil 11, It is set to 5 mm or more. A slit 17 is formed between the connecting portions 16a and 16b and the connecting portions 16c and 16d of the lines L1 and L2. The slit 17 has a width W2 set to 1 mm or more and a length S set to 17 mm or more.

  As described above, in this embodiment, by forming the slits 17 in which the width W2 between the connection portions 16a and 16b and the connection portions 16c and 16d in each line L1 and L2 is set to 1 mm or more, The distance W1 between the connecting portions 16a and 16b and the connecting portions 16c and 16d in the lines L1 and L2 can be separated as much as possible. In this way, a space is formed by the slit 17 between the connection portions 16a and 16b and the connection portions 16c and 16d, and the interval W1 between the connection portions 16a and 16b and the connection portions 16c and 16d in each line L1 and L2 is 5 mm. As described above, stray capacitance generated between the connection portions 16a and 16b to which the choke coil 11 is connected and the connection portions 16c and 16d can be reduced. In addition, since the stray capacitance can be escaped from the slit 17 or hardly generated, the stray capacitance generated between the connection portions 16a and 16b to which the choke coil 11 is connected and the connection portions 16c and 16d is more effectively used. Can be reduced. Further, in this embodiment, the connection portions 16a and 16b to which the choke coil 11 is connected and the widths W of the connection portions 16c and 16d are formed to be 4 mm or less, thereby reducing the surface areas of the connection portions 16a to 16d. Therefore, stray capacitance generated between the connection portions 16a and 16b and the connection portions 16c and 16d can be further reduced. That is, the stray capacitance generated between the connection portions 16a and 16b and the connection portions 16c and 16d is proportional to the interval W1 between the connection portions 16a and 16b and the connection portions 16c and 16d, and inversely proportional to the area of each connection portion 16a to 16d. Therefore, setting the interval W1 between the connection portions 16a and 16b and the connection portions 16c and 16d as wide as possible and reducing the areas of the connection portions 16a and 16b and the connection portions 16c and 16d reduces the stray capacitance. This is extremely effective, and the noise removal effect can be further improved by reducing the stray capacitance. In addition, in this embodiment, the slit 17 is simply formed in the circuit board 10 without adding a countermeasure component for removing the stray capacitance, so there is no fear of increasing the number of components and contributing to cost reduction. it can.

  As mentioned above, although the present Example was explained in full detail, this invention is not limited to the said Example, A various deformation | transformation implementation is possible within the range of the summary of this invention. For example, the circuit configuration of the line filter or the shape of the slit is not limited to the above embodiment, and may be selected as appropriate.

It is explanatory drawing of the state which connected the choke coil which shows one Example of this invention. It is sectional drawing which shows the state which connected the choke coil to the circuit board same as the above. It is a circuit diagram which shows the conventional line filter circuit. It is explanatory drawing which shows the stray capacitance by a pattern same as the above.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Circuit board 10A Wiring pattern 13, 14 Winding 11 Choke coil 15a-15d Terminal 16a-16d Connection part W Connection part width W1 Connection part interval W2 Slit width S Slit length

Claims (4)

  In a circuit board comprising a line filter in which a wiring pattern of a line filter circuit is formed on a circuit board and a terminal of a choke coil constituting the line filter is connected to a connection part formed in a line of the line filter circuit, the connection A circuit board provided with a line filter circuit, characterized in that a part is formed apart and a slit is formed between these connection parts.   The circuit board provided with the line filter circuit according to claim 1, wherein an interval between the connection portions is 5 mm or more.   The circuit board having a line filter circuit according to claim 1, wherein the slit has a length of 17 mm or more and a width of 1 mm or more.   The width of the said connection part is 4 mm or less, The circuit board provided with the line filter circuit of any one of Claims 1-3 characterized by the above-mentioned.

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