JP2018078205A - Circuit board - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a circuit board comprising a noise filter which has high noise removal effects and is inexpensive and free of a fault.SOLUTION: The present invention relates to a circuit board (100) comprising a processing circuit (122) which processes an input signal and a drive circuit (124) which controls a controlled object based upon the output of the processing circuit. The circuit board comprises at least a power supply terminal (119), a power supply line (113) connecting the power supply terminal to an object of power supply, a ground pattern (132) connected to the processing circuit, a ground pattern (130) connected to the drive circuit, and an electrically conductive pattern (116a, 116b) electrically connected to one of respective ground patterns, and the electrically conductive pattern is arranged along the power supply line at a predetermined distance to an outer edge of the power supply line at least partially in the proximity to the power supply terminal of the power supply line, thereby constituting capacitive coupling to the power supply line.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a circuit board, and more particularly to a circuit board including a noise filter using a circuit pattern.

  Generally, a noise filter is mounted on a circuit board on which an electronic circuit is mounted in order to prevent malfunction due to, for example, high frequency noise superimposed on a power supply line. For example, by inserting a noise filter consisting of a bypass capacitor between the power line and the ground line, the high-frequency noise is released to the ground line via a bypass capacitor having a low high-frequency impedance, and is thus removed from the power line. Removed.

  The high frequency noise superimposed on the power supply line or the like may include, for example, a plurality of noise components composed of the operating frequency of the electronic circuit and its harmonics, and a plurality of bypass capacitors are used to remove each noise component. It may be mounted on a circuit board.

  Further, depending on the magnitude of the superimposed high-frequency noise current, for example, an overcurrent flows through the bypass capacitor, and the bypass capacitor may be short-circuited, and in the worst case, the power supply line and the ground line may be short-circuited. In order to avoid such a situation, for example, a spare bypass capacitor is added in series with the main bypass capacitor, and even if one of the bypass capacitors is short-circuited, the circuit board can function so that the other bypass capacitor functions. However, according to such a method, the number of bypass capacitors mounted on the circuit board is further increased.

  As a bypass capacitor, a multilayer ceramic capacitor is usually used. However, in a general-purpose multilayer ceramic capacitor, an equivalent series inductance (ESL) increases at an operating frequency exceeding several hundred MHz, and a resonance circuit is formed. The characteristic of reflecting and reflecting much of the high frequency noise to be configured and removed appears significantly. As a result, the high frequency noise reflected by the multilayer ceramic capacitor propagates through the power supply line and the like to emit radiation noise, and the radiation noise is superimposed on other wiring lines and circuit components.

  In order to reduce such reflection noise, for example, there is a method of using a bypass capacitor having a sufficiently low ESL at the operating frequency of the electronic circuit. However, if all of the plurality of bypass capacitors as described above are replaced with expensive low ESL bypass capacitors, the cost of the circuit board cannot be avoided.

  As described above, the circuit board configured as described above requires a large number of expensive noise filters, which not only increases the component cost but also increases the occupancy ratio of the noise filters in the circuit board. There is a problem that the degree of freedom of arrangement of electric parts is limited.

Japanese Patent Laid-Open No. 2006-143845

  From such a background, it is desired to realize a circuit board including a noise filter that can efficiently remove high-frequency noise, is inexpensive, and has no short-circuit failure.

One embodiment of the present invention is a circuit board including a processing circuit that processes an input signal and a driving circuit that controls a control target based on an output of the processing circuit. The circuit board includes a power supply terminal, a power supply line connecting the power supply terminal and a power supply target, a ground pattern connected to the processing circuit, and a ground pattern connected to the drive circuit, At least a conductive pattern electrically connected to one of the ground patterns, the conductive pattern being at least partially adjacent to the power supply terminal of the power supply line and a predetermined outer edge of the power supply line. The power supply line is disposed along the power supply line with a distance of 1 to form a capacitive coupling with the power supply line.
According to another aspect of the present invention, the conductive pattern includes two conductive patterns, and the two conductive patterns are arranged so as to face each other with the power supply line interposed therebetween.
According to another aspect of the present invention, the conductive pattern is wider than the power supply line, and is disposed directly below the power supply line via an insulating layer.
According to another aspect of the present invention, the circuit board includes at least a connector that is electrically connected to an external power source, and the power supply terminal is a connection terminal that electrically connects the connector and the circuit board. Of these, the connection terminal is connected to the power supply potential of the external power supply.
According to another aspect of the invention, the power supply terminal is a power output terminal of a power circuit mounted in the circuit board.
According to another aspect of the invention, the conductive pattern is connected to a ground pattern of the processing circuit.
According to another aspect of the present invention, the power supply target is the drive circuit, and the conductive pattern is connected to a ground pattern of the drive circuit.
According to another aspect of the present invention, there is provided an electronic device including the circuit board and a housing that houses the circuit board therein.

It is a figure which shows the structure of the circuit board which concerns on 1st Embodiment of this invention. It is a figure which shows the structure of the circuit board which concerns on the modification of 1st Embodiment of this invention. It is a figure which shows the structure of the circuit board which concerns on the modification of 1st Embodiment of this invention. It is a figure which shows the structure of the circuit board which concerns on 2nd Embodiment of this invention. It is a figure which shows the structure of the circuit board which concerns on 3rd Embodiment of this invention.

  Embodiments of the present invention will be described below with reference to the drawings. In this embodiment, a circuit board constituting an electronic device such as an electronic control unit (ECU) mounted on a vehicle is shown as a circuit board according to the present invention. The configuration is not limited to this and can be widely applied to general electronic devices.

[First Embodiment]
FIG. 1 is a diagram showing a configuration of an electronic device on which a circuit board according to a first embodiment of the present invention is mounted. The circuit board 100 is a circuit board that constitutes an electronic device 10 that is mounted on a vehicle and performs engine control of the vehicle, and on which electronic components that constitute a control circuit are mounted. In addition, the circuit board 100 is a rectangular flat plate, and is composed of, for example, a multilayer board (for example, a multilayer printed wiring board) in which a plurality of insulator layers having a predetermined dielectric constant are stacked. The circuit board 100 is provided with a connector 102, and receives a signal from a sensor (not shown) mounted outside the electronic device 10 through the connector 102, and controls the engine and the like. A control signal or the like is transmitted to (not shown). Since the circuit board 100 on which the connector 102 is mounted is housed in the housing 104, the circuit board 100 cannot be visually recognized from the outside of the housing 104. However, in FIG. The part which is mainly inside is also shown using a solid line.

  The housing 104 is provided with flanges 106 and 108 on the outer surface thereof. The housing 104 and the flanges 106 and 108 are both made of a conductive material such as a metal (for example, aluminum). The housing 104 is mechanically fixed to the vehicle body 110 by the flanges 106 and 108 and the vehicle body 110. Are electrically connected directly.

  The circuit board 100 includes a power supply circuit 120, a processing circuit 122, a drive circuit 124, and the like, and is electrically connected to and controlled by an electric circuit pattern (wiring line) such as a copper foil formed on the circuit board 100. The circuit is configured. In FIG. 1, the line segment connecting the power supply circuit 120, the processing circuit 122, the drive circuit 124, and the like shown on the circuit board 100 schematically shows an electric circuit pattern formed on the circuit board 100. The black circles shown at the intersections of the line segments indicate that the electric circuit patterns are electrically connected to each other at the intersections. Further, the intersection of the line segments not indicated by black circles indicates that the electric circuit pattern constituting the intersection is not electrically connected. For example, in the intersection, one electric circuit pattern However, the electrical connection is avoided by escaping to the inside or the back side of the circuit board 100 through via holes or the like provided in the circuit board 100. In addition to the electronic circuit and circuit pattern described in FIG. 1, various electronic circuits and circuit patterns may be formed on the circuit board 100. However, in order to simplify the drawing and facilitate understanding, FIG. These are not shown in FIG.

  The power supply circuit 120 receives, for example, a voltage (for example, 12V) supplied from an external power supply 107 configured by an in-vehicle generator or a battery via the power supply line 109, the connector lead 119 of the connector 102, and the power supply line 113. The voltage is converted into a predetermined voltage value (for example, 5 V) and supplied to the processing circuit 122 or the like.

  The processing circuit 122 includes, for example, a CPU, an AD converter (analog-to-digital converter), a logic circuit device such as an AND circuit or an OR circuit, a PLD (Programmable Logic Device), an ASIC (Application Specific Integrated). A control object (not shown), which is configured by a digital circuit such as a circuit) and is arranged outside the electronic device 10 based on a sensor signal received from a sensor (not shown) provided outside the electronic device 10. A control amount for controlling is calculated. The sensor is a sensor that detects an operation amount for controlling the control target, and is, for example, a speed sensor, an acceleration sensor, an engine rotation sensor, or the like. Further, the control target may be, for example, various actuators that operate a brake, an engine throttle, an electromagnetic valve provided in a fuel supply pipe, and the like that affect the running of the vehicle.

  The drive circuit 124 is configured by a power amplification circuit using a transistor such as a MOSFET (Metal-Oxide-Semiconductor Field-Effect Transistor), and power is supplied from the external power source 107 via the connector lead 125, the power supply line 127, and the like. The current or voltage value to be applied to the control target is determined based on the control amount received from the processing circuit 122, and an output having the determined current or voltage value is output to the control target.

  An external connector 112 fitted to the connector 102 is connected to the connector 102 mounted on the circuit board 100. Thus, the electronic circuit on the circuit board 100 is electrically connected to, for example, the external power source 107 and the like placed outside the electronic device 10 via the external connector 112 and the wire harness 114 connected to the external connector 112. Connected. The wire harness 114 includes a power supply line 109 that supplies the power supply potential V of the external power supply 107 to the circuit board 100 and a ground line 111 that supplies a ground potential of the external power supply 107.

  For example, a power ground (PG) pattern 130 and a logic circuit ground (LG) pattern 132 are provided on a part of the outer periphery of the circuit board 100. In the present embodiment, the PG pattern 130 is arranged on the lower side of the circuit board 100 in FIG. 1 and the LG pattern 132 is arranged on the upper side of the circuit board 100 in FIG.

  The ground of the drive circuit 124 is connected to the PG pattern 130 via the wiring line 129. The PG pattern 130 is electrically connected to the housing 104 via a conductor plate 134 made of a conductor, and is electrically connected to the vehicle body 110 via the flange 108 and the like of the housing 104. It is connected to the ground terminal of the external power source 107 via the vehicle body 110. Here, the conductor plate 134 can be formed of, for example, a copper plate, and the connection of the conductor plate 134 and the housing 104 can be performed by, for example, soldering. However, the electrical connection between the PG pattern 130 and the housing 104 is not limited to this. For example, the circuit board 100 is sandwiched between members constituting the housing 104 and the PG pattern 130 and the housing 104 are directly connected. The electrical connection can also be made by contact.

  The LG pattern 132 is connected to the ground terminal GND of the external power source 107 via a wiring line 115 formed on the circuit board 100, a conductive pattern 116a, and ground lines 111a and 111. The LG pattern 132 is connected to the ground of the processing circuit 122 via a wiring line 139 formed on the circuit board 100, and the voltage of the pulse signal used for the internal operation and output signal to the processing circuit 122. A level, that is, a reference for defining the logical value of the pulse signal is given. Further, the LG pattern 132 is also connected to the ground of the power supply circuit 120 through the wiring line 139.

  Here, in the circuit board 100 in the present embodiment, in particular, two conductive patterns 116a and 116b are provided so as to face each other with the power supply line 113 sandwiched therebetween, and the conductive patterns 116a and 116b High frequency noise superimposed on the power supply line 113 is removed.

  Specifically, the conductive patterns 116a and 116b run parallel to each other along the power supply line 113 at a predetermined distance from the outer edge of the power supply line 113 so as to form capacitive coupling with the power supply line 113. Is arranged. The conductive patterns 116a and 116b are connected to the connector 102 so as to sandwich the connection portion (black circle in the figure) between the connector lead 119 of the connector 102 to which the power supply potential V of the external power supply 107 is supplied and the power supply line 113. It is formed so that about 1/3 of the length of the power supply line 113 in the horizontal direction in the figure extends from a connection portion with the connector leads 121 and 123 erected on the side to a position sandwiched between both conductive patterns. .

  The conductive patterns 116a and 116b can be formed of an electric circuit pattern (wiring line) made of copper, aluminum, or the like, like other wiring lines. The conductive pattern 116a is connected to the LG pattern 132 via the wiring line 115. Further, the conductive pattern 116a and the conductive pattern 116b are electrically connected to each other by the wiring 111a and the wiring 111b inside the external connector 112. In addition to being connected, it is electrically connected to the ground GND of the external power source 107 through the ground line 111.

  With this configuration, in the circuit board 100 according to the present embodiment, the capacitance formed by the conductive patterns 116 a and 116 b provided on both sides in the extending direction (the horizontal direction in the drawing) of the power supply line 113 and the power supply line 113. The coupling functions as a bypass capacitor having a low impedance with respect to the high frequency noise superimposed on the power supply line 113, and the high frequency noise is immediately eliminated to the ground GND of the external power source 107 through the conductive patterns 116a and 116b. The capacitance of the bypass capacitor is determined by the distance between the power supply line 113 and the conductive patterns 116a and 116b and the length in the extending direction of the conductive patterns 116a and 116b (the horizontal direction of the conductive patterns 116a and 116b in the figure). Therefore, a desired impedance corresponding to the frequency of the superimposed high frequency noise can be configured by adjusting the distance and the length. In addition, the conductive patterns 116a and 116b may be configured to have different lengths, or the distance between the power supply line 113 and the conductive pattern 116a and the distance between the power supply line 113 and the conductive pattern 116b. By configuring them differently, two bypass capacitors having different capacities can be provided on both sides of the power supply line 113.

  The high frequency noise flowing into the power supply line 113 from the outside of the circuit board 100 is always removed at the connection portion between the circuit board 100 and the outside (connection portion between the circuit board 100 and the connector lead 119). Therefore, for example, even if high-frequency noise superimposed on the power supply line 109 flows into the circuit board 100, it is immediately removed. Therefore, abnormalities in the control operation of the electronic circuit formed on the circuit board 100 and generation of control errors are caused. Is effectively prevented. Further, since the high frequency noise is not superimposed except in the vicinity of the connection portion of the power supply line 113, there is no possibility of becoming a noise source that emits radiation noise.

  In general, high-frequency noise in a wiring line is concentrated and distributed near the outer edge of the wiring line due to the skin effect, but in the circuit board 100, the high-frequency noise in the power supply line 113 follows the distribution of the high-frequency noise. Since the conductive patterns 116a and 116b are arranged so as to face both outer edges of the power supply line 113, high frequency noise can be efficiently removed from the power supply line 113.

  Further, since the conductive patterns 116a and 116b are connected to the LG pattern 132 that reduces the high frequency noise and provides a stable potential as compared with the PG 130, the high frequency noise flows backward from the conductive patterns 116a and 116b to the power supply line 113. There is no fear of doing. Further, since the conductive patterns 116a and 116b are provided in the middle of the return portion from the LG pattern 132 to the ground GND of the external power supply 107, the LG pattern 132 is caused by noise released to the conductive patterns 116a and 116b. Does not disturb the potential. For this reason, the circuit operations of the power supply circuit 120 and the processing circuit 122 in which the ground is connected to the LG pattern 132 are not adversely affected.

  Further, even if a large noise current flows into the bypass capacitor formed by the conductive patterns 116a and 116b and the power supply line 113, the conductive pattern 116a in the extending direction of the power supply line 113 (the horizontal direction in the drawing). , 116b are formed so as to constitute a counter electrode over a long distance, so that the amount of current per unit length can be suppressed by dispersing and releasing the noise current over the counter electrode. For this reason, it is possible to protect the bypass capacitor from being destroyed due to an excessive inflow of noise current.

  Further, in the present embodiment, the bypass capacitor constituted by the conductive patterns 116a and 116b and the power supply line 113 has a distance between opposing electrodes (for example, the length of the gap between the conductive pattern 116a and the power supply line 113). Is a so-called LW reverse type capacitor having a configuration shorter than the dimension in the length direction of the electrode (the length of the conductive patterns 116a and 116b in the horizontal direction in the drawing). In general, in the LW reverse type capacitor, even when the operating frequency is increased, the equivalent series inductance is small and the formation of a resonance circuit is suppressed. Similarly, since the equivalent series inductance can be reduced in the bypass capacitor in the circuit board 100 of the present embodiment, the high frequency noise can be quickly removed to the conductive patterns 116a and 116b without being reflected, There is no possibility that high frequency noise is superimposed on the power supply line 113 again.

  As described above, the bypass capacitor configured by the conductive patterns 116a and 116b and the power supply line 113 mounted on the circuit board 100 of the present embodiment reliably removes high-frequency noise, and excessive noise current is generated. In case of inflow, it will not be destroyed. Furthermore, since the bypass capacitor formed on the circuit board 100 of the present embodiment is configured using only the circuit pattern formed on the circuit board 100, it can be formed at low cost, and can be formed with individual components. Compared with the case where a certain noise filter is mounted on a circuit board, a significant cost reduction can be realized.

  In the present embodiment, the conductive patterns 116a and 116b are formed so as to sandwich the connecting portion (black circle in the figure) between the connector lead 119 and the power supply line 113. However, the present invention is not limited to this. For example, if at least a part of the power supply line 113 is formed so as to be sandwiched between the conductive patterns 116a and 116b, a certain effect can be obtained. In the present embodiment, 1/3 of the length of the power supply line 113 (the length in the left-right direction in the drawing) is formed between the conductive patterns 116a and 116b. Both conductive patterns 116a and 116b may be formed so that the entire length of 113 is sandwiched.

  In the present embodiment, the conductive pattern 116a and the conductive pattern 116b are electrically connected by connecting the wiring 111a and the wiring 111b in the external connector 112. However, the present invention is not limited to this. Both of the conductive patterns 116a and 116b may be electrically connected using a metal wiring or via formed in the 100.

  In the present embodiment, the conductive patterns 116a and 116b are provided in the middle of the return portion from the LG pattern 132 to the ground GND of the external power source 107. However, the present invention is not limited to this, and the conductive patterns 116a and 116b The circuit pattern may be configured to reach the ground GND of the external power supply 107 via the LG pattern 132.

  2 and 3 are modifications of the circuit board 100 according to the first embodiment, and show the shapes of the first, second, and third conductive patterns that can be used in place of the conductive patterns 116a and 116b. ing.

  FIG. 2A is a diagram showing a configuration of a circuit board 200a on which a noise filter according to a first modification of the first embodiment is formed, and a part of connector leads of the circuit board 200a and the connector 202a. It is a partial detail drawing which shows the vicinity of a connection part with 219a, 221a, etc. A conductive pattern 216, which is the first conductive pattern, is provided around the connection portion (black circle in the figure) between the connector lead 219a to which the power supply potential V of the external power supply 107 is supplied through the power supply line 209a and the power supply line 213a. It is formed in a letter shape and is provided so as to surround three sides (upper and lower left directions in the drawing) of the connection portion. Further, a part of the conductive pattern 216 is electrically connected to the LG pattern 132 (FIG. 1) by the wiring pattern 215a, and the other part of the conductive pattern 216 includes the connector lead 221a and the wiring 211a. And is electrically connected to the ground GND (FIG. 1) of the external power source 107.

  Thus, by arranging the conductive pattern 216 as the first conductive pattern so as to surround the connection portion, noise superimposed on the power supply line 213a is also removed from the portion near the connector 202a of the connection portion. Therefore, noise removal efficiency can be increased. Moreover, since radiation noise emitted from the power supply line 213a to the connector 202a side is absorbed, it is possible to effectively suppress the power supply line 213a from becoming a noise radiation source.

  FIG. 2B is a diagram showing a configuration of a circuit board 200b on which a noise filter according to a second modification of the first embodiment is formed, and a part of connector leads of the circuit board 200b and the connector 202b. It is a partial detail drawing which shows the vicinity of a connection part with 219a, 221b, 223b etc. FIG. In the outer edge portions of the conductive patterns 216b and 216c, which are the second conductive patterns, each outer edge portion facing the power supply line 213b is in contact with the outer edge of the power supply line 213b according to the distance from the connector leads 221b and 223b. It has a step-like shape such that the distance between the gaps is reduced stepwise. One end of the conductive pattern 216b is electrically connected to the LG pattern 132 (FIG. 1) by the wiring pattern 215b, and the other part of the conductive pattern 216b is connected via the connector lead 221b and the wiring 211b. Thus, it is electrically connected to the ground GND (FIG. 1) of the external power source 107. Furthermore, the conductive pattern 216b and the conductive pattern 216c are electrically connected to each other by vias, wirings 220b, and the like inside the circuit board 200b.

  In this way, by configuring the power supply line 213b and the conductive patterns 216b and 216c so that the inter-electrode distances are gradually different, a plurality of bypass capacitors having different capacitances are provided on the circuit board 200b. Can be configured. The capacitance of each of the plurality of bypass capacitors can be adjusted according to the distance between the electrodes of the power supply line 213b and the conductive patterns 215b and 216c, so that, for example, noise including a plurality of frequency components supplies power. In the case of being superimposed on the line 213b or the like, if each of the capacitances is adjusted so as to obtain a desired impedance corresponding to each of the frequency components, it differs depending on the capacitance. The high frequency noise of the frequency component can be surely released to the conductive patterns 216b and 216c.

  In this modification, the outer edge portions of the conductive patterns 216b and 216c are configured to be stepped, but the present invention is not limited to this. For example, each of the outer edge portions of the conductive patterns 216b and 216c and the power supply line You may comprise so that the clearance gap with the outer edge of 213b may become narrow gradually continuously. Further, the shape of the outer edge portion of the conductive patterns 216b and 216c facing the power supply line 213b is not limited to a step shape, and may be any shape as long as it has capacitive coupling with a desired capacitance.

  FIG. 3A is a top view showing a configuration of a circuit board 300 on which a noise filter according to a third modification of the first embodiment is formed, and a part of connectors of the circuit board 300 and the connector 302 is shown. FIG. 3 is a partial detail view showing the vicinity of a connection portion with leads 319, 321 and the like, and FIG. 3B is a perspective view thereof. The circuit board 300 is constituted by, for example, a multilayer board (for example, a multilayer printed wiring board) in which insulator layers 330, 340, and 350 having a predetermined dielectric constant are stacked, and the circuit board 300 is indicated by a dotted line in FIG. The conductive pattern 316 that is the third conductive pattern is formed on the insulating layer 340 that is the inner insulating layer, and constitutes a bypass capacitor having the power supply line 313 and the insulating layer 330 as dielectric layers. Further, the width of the conductive pattern 316 (vertical length in FIG. 3A) is wider than the width of the power supply line 313 (vertical length in FIG. 3A). Has been. Further, a part of the conductive pattern 316 is electrically connected to the LG pattern 132 (FIG. 1) by a wiring pattern 315 formed on the upper surface of the insulating layer 340 in the drawing, and another part of the conductive pattern 316 is also connected. This part is electrically connected to the ground GND (FIG. 1) of the external power source 107 through the connector lead 321 and the ground line 311 connected by the vias indicated by dotted lines in FIG.

  As described above, by disposing the conductive pattern 316 wider than the power supply line 313 via the insulating layer 330 serving as a dielectric immediately below the power supply line 313, leakage occurs from the width direction of the power supply line 313. Since a bypass capacitor capable of causing the electric field component to reach the conductive pattern 316 can be configured, high-frequency noise superimposed on the power supply line 313 can be surely released to the conductive pattern 316 without leakage, It becomes possible to efficiently remove high-frequency noise concentrated and distributed near the back of the outer edge of the supply line 313.

[Second Embodiment]
Next, a circuit board according to a second embodiment of the present invention will be described. In the circuit board according to the present embodiment, the conductive pattern is provided so as to sandwich both sides of the power supply line output from the power supply circuit provided in the circuit board. Thereby, in the electronic circuit according to the present embodiment, high-frequency noise superimposed on the power supply line output from the power supply circuit provided in the circuit board can be efficiently removed.

FIG. 4 is a diagram showing a configuration of an electronic circuit according to the second embodiment of the present invention. In the circuit board 400 shown in FIG. 4, the same components as those of the circuit board 100 according to the first embodiment shown in FIG. 1 are denoted by the same reference numerals as those shown in FIG. The description about FIG. 1 is used.

  The circuit board 400 is a circuit board that can be used in place of the circuit board 100 according to the first embodiment. Conductive patterns 416a and 416b are formed on the surface of the circuit board 400. The conductive patterns 416a and 416b are arranged so as to sandwich a power supply line 117 for supplying power from the power supply circuit 120 to the processing circuit 122 from both sides (left and right in the drawing), and in particular, an output terminal for the power supply potential of the power supply circuit 120. And at least a portion where the power supply line 117 is connected is provided. One end of the conductive pattern 416a is electrically connected to the LG pattern 132 by a wiring line 415. Further, another part of the conductive pattern 416a is connected to the power supply 107 by a connector lead 421, a ground line 411, or the like. It is electrically connected to the ground GND. In addition, the conductive pattern 416a and the conductive pattern 416b are electrically connected to each other by vias, wirings, or the like inside the circuit board 400.

  With this configuration, the conductive patterns 416a and 416b and the power supply line 117 are capacitively coupled to form, for example, a bypass capacitor having a low impedance against high frequency noise superimposed on the power supply line 117 from the power supply circuit 120. The high-frequency noise released from the power supply line 117 to the conductive patterns 416a and 416b is immediately eliminated to the ground GND of the external power source 107 through the connector lead 421 and the ground line 411. The power supply line 117 does not become a noise source that emits noise to other wiring lines such as signal lines because most of the power supply line 117 is not likely to be superposed with high-frequency noise. Thereby, it is possible to prevent an abnormality in the control operation of the electronic circuit formed on the circuit board 400.

[Third Embodiment]
Next, a circuit board according to a third embodiment of the present invention will be described. In the circuit board 500 according to the present embodiment, conductive patterns are provided so as to sandwich both sides of a power supply line that supplies power to the drive circuit. As a result, in the electronic circuit according to the present embodiment, the power supply noise superimposed on the power supply line that supplies power to the drive circuit can be effectively removed, and control abnormality and control error of the drive circuit can be generated. Prevent in advance.

FIG. 5 is a diagram showing a configuration of an electronic circuit according to the third embodiment of the present invention. In the circuit board 500 shown in FIG. 5, the same components as those of the circuit board 100 according to the first embodiment shown in FIG. 1 are denoted by the same reference numerals as those shown in FIG. The description about FIG. 1 is used.

  The circuit board 500 is a circuit board that can be used in place of the circuit board 100 according to the first embodiment. Conductive patterns 516a and 516b are formed on the surface of the circuit board 500. The conductive patterns 516 a and 516 b are provided so as to sandwich both sides of the power supply line 127 connected to the connector lead 525 that supplies power from the external power supply 107. One end of each of the conductive patterns 516a and 516b is connected to the PG pattern 130 by wiring lines 526a and 526b.

  With this configuration, the capacitive coupling formed by the conductive patterns 516 a and 516 b provided so as to face the outer edge of the power supply line 127 and the power supply line 127 can prevent high frequency noise superimposed on the power supply line 127. And functions as a low impedance bypass capacitor. The high-frequency noise released from the power supply line 127 to the conductive patterns 516a and 516b is immediately eliminated to the housing 104 through the wiring lines 526a and 526b, the PG pattern 130, and the conductor plate 134. In general, since a large current flows into and out of the drive circuit, the noise current removed by the conductive patterns 516a and 516b of the circuit board 500 is larger than the noise current removed by the first and second embodiments. It will be big. For this reason, when the conductive patterns 516a and 516b are connected to the LG pattern 132 as in the first and second embodiments, for example, the potential of the LG pattern 132 becomes unstable due to the inflow of noise, and the LG pattern There is a risk of adversely affecting the circuit operations of the power supply circuit 120 and the processing circuit 122 connected to the pattern 132. For this reason, the conductive patterns 516a and 516b are preferably connected to the PG pattern 130 into which a larger current flows than the LG pattern 132.

  As described above, the circuit board 500 is configured such that high-frequency noise flowing into the power supply line 127 from the connector lead 525 is always removed in the vicinity of the inflow port. Even when noise flows in, it is immediately removed. As a result, there is no possibility of noise being superimposed on the other power lines such as signal lines from the power supply line 127, and an abnormal control operation of the electronic circuit formed on the circuit board 500 and generation of a control error can be effectively performed. Can be prevented.

  As described above, the circuit boards according to the first, second, and third embodiments have the processing circuit 122 that processes the input signal and the drive circuit 124 that controls the control target based on the output of the processing circuit. A circuit board 100 provided with a power supply terminal 119, a power supply line 113 connecting the power supply terminal and the power supply target 120, etc., and the processing circuit. Ground pattern 132, ground pattern 130 connected to the drive circuit, and conductive patterns 116a, 116b, etc. electrically connected to one of the ground patterns. At least part of the line adjacent to the power supply terminal, along the power supply line at a predetermined distance from the outer edge of the power supply line Cormorant to arranged that it constitutes a power source supply line and the capacitive coupling.

  With this configuration, the power supply line and the conductive pattern constitute a bypass capacitor having a low impedance with respect to the high frequency noise, and the high frequency noise can be eliminated to the ground through the conductive pattern. Further, since the noise current that is eliminated is dispersed and escaped across the counter electrode, the amount of current flowing in per unit length can be suppressed, and destruction of the bypass capacitor can be prevented. Furthermore, in the bypass capacitor formed on the circuit board according to the present invention, since the equivalent series inductance can be reduced, the bypass capacitor can efficiently remove the high frequency noise without reflecting the high frequency noise. it can. Furthermore, since the bypass capacitor formed on the circuit board of the present invention is configured using only the circuit pattern formed on the circuit board, it can be formed at low cost, and a noise filter that is an individual component can be provided. Compared to mounting on a circuit board, a significant cost reduction can be realized.

  In each of the circuit boards of the first to third embodiments and the modifications thereof, a conductive pattern is arranged on one power supply line formed on the circuit board, and the high frequency superimposed on the one power supply line. Although only the noise is removed, the present invention is not limited to this. For example, any one of the conductive patterns shown in the first to third embodiments and the modifications thereof is applied to all power supply lines formed on the circuit board. can do.

  The housing 104 is composed of, for example, two supports, a cover and a base, and the cover and the base are fixed to each other by screws or the like to form an internal cavity, and the circuit of the present invention is formed in the internal cavity. It is good also as what accommodates a board | substrate. In this case, the cover and the base are made of a conductive material such as metal (for example, aluminum), and at least one of the two supports is arranged so as to be in contact with the surface of the PG pattern 130. The circuit board can be fixed in the casing by sandwiching the circuit board in the thickness direction at the contact position. With such a configuration, the PG pattern 130 and the housing 104 can be easily electrically connected.

  In this embodiment, a multilayer board is used as the circuit board. However, the present invention is not limited to this, and a single-layer printed board may be used, for example.

  Note that the present invention is not limited to the above-described embodiment, and can be modified and used without departing from the spirit of the present invention.

  10, 40, 50 ... Electronic device, 100, 200a, 200b, 300, 400, 500 ... Circuit board, 102, 202a, 202b, 302 ... Connector, 104 ... Housing, 106, 108 ... Flange, 107 ... External power supply, 109 ... Power supply line, 110 ... Car body, 111, 211a, 211b, 311, 411, 511 ... Ground line, 113, 117, 213a, 213b, 313: power supply line, 114: wire harness, 116a, 116b, 216, 216b, 216c, 316, 416a, 416b, 516a, 516b ... conductive pattern, 119, 121, 123, 219a, 221a, 219b, 221b, 223b, 319, 321, 419, 421, 519, 521, 525 ... 120 ... Power supply circuit, 122 ... Processing circuit, 124 ... Drive circuit, 130 ... PG pattern, 132 ... LG pattern, 134 ... Conductor plate, 330, 340, 350 ..Insulator layers.

Claims (8)

A circuit board including a processing circuit for processing an input signal and a driving circuit for controlling a control target based on an output of the processing circuit;
The circuit board is
A power supply terminal;
A power supply line connecting the power supply terminal and a power supply target;
A ground pattern connected to the processing circuit;
A ground pattern connected to the drive circuit;
A conductive pattern electrically connected to one of the ground patterns;
Comprising at least
The conductive pattern is disposed along the power supply line at a predetermined distance from an outer edge of the power supply line in at least a part of the power supply line adjacent to the power supply terminal. And capacitive coupling,
Circuit board. The circuit board according to claim 1,
The conductive pattern consists of two conductive patterns,
The two conductive patterns are arranged so as to face each other across the power supply line,
Circuit board. The circuit board according to claim 1,
The conductive pattern is wider than the power supply line, and is disposed directly below the power supply line via an insulating layer.
Circuit board. The circuit board according to any one of claims 1 to 3,
The circuit board includes at least a connector electrically connected to an external power source,
The power supply terminal is a connection terminal connected to a power supply potential of the external power source among connection terminals for electrically connecting the connector and the circuit board.
Circuit board. The circuit board according to any one of claims 1 to 3,
The power supply terminal is a power output terminal of a power circuit mounted in the circuit board.
Circuit board. The circuit board according to claim 4 or 5,
The conductive pattern is connected to a ground pattern of the processing circuit.
Circuit board. The circuit board according to claim 4,
The power supply target is the drive circuit,
The conductive pattern is connected to a ground pattern of the drive circuit.
Circuit board. A circuit board according to any one of claims 1 to 7,
A housing that houses the circuit board therein;
An electronic device comprising:

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