JP6696071B2 - Output noise reduction device - Google Patents

Description

  The technology disclosed in the present application relates to an output noise reduction device that suppresses noise mixed in an output signal, and more particularly to a noise reduction device that includes an inductance element that is inserted in a signal path of an output signal.

  2. Description of the Related Art Conventionally, switching noise of an operating frequency of an electronic device or a harmonic frequency thereof may be mixed in an output voltage or an output signal output from a switching power supply or another electronic device via a conductive bar. Such noise may adversely affect external electronic devices, and it is necessary to suppress it as necessary. In a switching power supply, when an output voltage having a predetermined voltage value is output by a switching operation of a power transistor, switching of a current path by turning on / off a power transistor causes noise at a switching frequency and its harmonic frequency depending on an output rating. It is conceivable that this noise is superimposed on the output voltage and propagates to the external electronic device via the conductive bar. In particular, when a switching power supply is mounted in an automobile, there is a problem that, depending on the switching frequency, noise of the switching frequency and its harmonic frequency is superimposed on audio signals, which adversely affects viewing, that is, so-called radio noise occurs. is there.

  In order to suppress such noise, an output noise reducing device such as an inductance element such as a choke coil or a combination of a choke coil and a capacitor is inserted in an output path such as an output voltage (Patent Documents 1, 2, 3, etc.). .. The switching power supply device described in Patent Document 1 includes an output filter including a smoothing capacitor and a smoothing reactor in an output path. In addition, the switching power supply device described in Patent Document 2 includes a core unit configured by surrounding a bus bar that is an output path with a magnetic core. This magnetic core functions as a noise filter. Patent Document 3 describes a noise reduction device including an inductance element inserted in a signal path of an output signal of a switching power supply device and other electronic devices.

JP2012-210002 JP, 2005-93536, A JP, 2016-34180, A

  In the output noise reduction devices described in Patent Documents 1 and 2, noise generated due to switching operation of a switching power supply and other electronic devices propagates around signal wiring or ground wiring and propagates. The output noise is not necessarily sufficiently suppressed because it is transmitted to the output terminal as radiation noise radiated by electromagnetic coupling such as inductive coupling. In particular, the noise source generated due to the switching operation or the like and the conductive bar or the output terminal are close to each other in terms of the circuit configuration, and they may be mounted close to each other. Therefore, the noise generated by the switching operation is radiated by electromagnetic coupling such as capacitive coupling and inductive coupling due to parasitic capacitance components and inductive components, and depends on the routing of signal paths and ground wiring and the mutual arrangement relationship. Propagation around the signal path or the ground wiring may reach the conductive bar or the output terminal without passing through the output path of the output noise reduction device having the original noise reduction function. Even if an output noise reduction device is provided on the output path such as the conductive bar toward the output terminal, noise is mixed into the conductive bar and the output terminal in front of this output noise reduction device, and noise cannot be sufficiently suppressed. There's a problem.

  In addition, the noise reduction device described in Patent Document 3 includes a choke coil that is an inductance element and a capacitor, and is located outside the metal housing of the switching power supply device and other electronic devices on the output terminal side of the choke coil. By arranging the section and the capacitor, it is possible to prevent the metal housing from exerting an electromagnetic shielding effect and propagating the radiation noise generated in the metal housing to the output terminal of the noise reduction device. However, since part of the noise reduction device is inside the metal housing of the switching power supply device and other electronic devices, part of the noise reduction device is exposed to radiation noise generated inside the metal housing, and the performance of the noise reduction device is reduced. There is a problem that it cannot be fully exerted.

  The technology disclosed in the present application has been proposed in view of the above problems, and is radiated by electromagnetic coupling caused by an electronic device housed in a metal housing or wraps around via an output terminal to be output. It is an object of the present invention to provide an output noise reduction device capable of suppressing the noise propagating to a device and sufficiently exhibiting the performance of the noise reduction device.

  In order to achieve the above object, the output noise reduction device according to claim 1 is an output noise reduction device that reduces noise mixed in an output signal from an electronic device, and is a metal that houses the electronic device and the output noise reduction device. A housing and a conductive bar formed of a conductive material, one end of which serves as a connection terminal for connecting to an output end of an electronic device, and the other end of which serves as an output terminal, and a conductive bar formed of a magnetic material. And a magnetic core having a through-hole penetrating therethrough, and at least one of the magnetic core and the output terminal or the magnetic core and the connection terminal, between the conductive bar and the metal housing. A capacitive element to be connected, and a mounting board having one surface serving as a mounting surface for mounting the capacitive element, and the other surface having a metal surface to which one terminal of the capacitive element is connected and having the same potential as the metal casing. Characterize.

  The output noise reduction device according to a second aspect is the output noise reduction device according to the first aspect, wherein the conductive bar and the magnetic core except the connection terminal and the output terminal are molded by a molding member formed of a resin material. It is characterized by

  An output noise reduction device according to a third aspect of the present invention is the output noise reduction device according to the first or second aspect, wherein the mounting substrate is arranged with its mounting surface facing the magnetic core.

  The output noise reduction device according to claim 4 is the output noise reduction device according to claim 3, wherein the output noise reduction device is a flat plate-shaped member that connects the metal surface of the mounting substrate to the metal housing, and is parallel to the conductive bar. It is characterized by comprising a connecting member that covers at least one of the body core and the conductive bar.

  An output noise reduction device according to a fifth aspect is the output noise reduction device according to the first or second aspect, wherein the mounting substrate has a mounting surface facing the metal casing and is provided between the magnetic core and the metal casing. It is characterized by being sandwiched.

  In the output noise reduction device according to the first aspect, the choke coil is formed between the output terminal and the connection terminal where the conductive bar penetrates the magnetic core and is connected to the output end of the electronic device. Furthermore, by providing a capacitive element that connects the conductive bar and the metal casing to at least one of the magnetic core and the output terminal or the magnetic core and the connection terminal, the LC type (L Type) or CLC type (π type) noise filter is formed. Thereby, the conduction noise generated from the electronic device and propagating in the signal path is suppressed. Further, the output noise reduction device is arranged in the metal casing together with the electronic device. Therefore, the radiation noise from the electronic device is suppressed from propagating to the output terminal. One surface of the mounting substrate is a mounting surface on which the capacitance element is mounted, and the other surface is a metal surface to which one terminal of the capacitance element is connected and which has the same potential as the metal case. As a result, the mounting surface is shielded, and the radiation noise of the electronic device generated in the metal housing with respect to the capacitive element is suppressed. As a result, the performance of the output noise reduction device as a filter can be sufficiently exhibited.

  In the output noise reduction device according to the second aspect, the portion of the choke coil formed by the conductive bar penetrating the magnetic core portion is molded by the molding member formed of the resin material. As a result, the conductive bar is kept in a state of penetrating the magnetic core portion, and is insulated from the metal casing which is a conductive member, so that the choke coil can be stably held. Thereby, the performance as a filter of the output noise reduction device composed of the choke coil and the capacitive element can be sufficiently exerted easily.

  In the output noise reduction device according to the third aspect, the mounting substrate is arranged with the mounting surface facing the magnetic core. As a result, the metal surface of the mounting board is arranged on the outer surface of the output noise reduction device. Since the output noise reduction device can be shielded entirely by the metal surface of the mounting substrate, the output noise reduction device can be effectively shielded.

  In the output noise reduction device according to claim 4, since the flat plate-shaped connecting member that connects the metal surface of the mounting board to the metal casing covers at least one of the magnetic core and the conductive bar, the metal surface of the mounting board is reduced. In addition, the connecting member can also shield the output noise reduction device. Therefore, a higher shield effect can be obtained.

  In the output noise reduction device according to claim 5, the mounting surface of the mounting substrate is a metal surface and a metal surface by sandwiching the mounting substrate between the magnetic core and the metal housing with the mounting surface facing the metal housing. It can be shielded by being sandwiched between the housing. As a result, the radiation noise of the electronic device generated in the metal housing with respect to the capacitive element can be suppressed more effectively, and the performance of the output noise reduction device as a filter can be sufficiently exhibited.

FIG. 3 is a circuit diagram when a noise filter module is connected to a switching power supply as an example of the output noise reduction device according to the first embodiment. It is a disassembled perspective view of the noise filter module of 1st Embodiment. It is a perspective view of the noise filter module of the first embodiment in a molded state. It is the top view seen from the state where the noise filter module of the first embodiment was molded. It is the top view (A) seen from above of the output noise reduction apparatus which concerns on 2nd Embodiment, the front view (B), the side view (C) seen from the output side, and the perspective view (D). It is the top view (A) seen from the top of the output noise reduction apparatus which concerns on 3rd Embodiment, the front view (B), the side view (C) seen from the output side, and the perspective view (D).

  FIG. 1 is a circuit diagram of a first embodiment according to the present application. As an example of the output noise reduction device, the case where the noise filter module 1 is connected between the output terminal VX and the output terminal VO of the switching power supply 5 is shown. The switching power supply 5 and the noise filter module 1 are housed in a metal housing 3 made of aluminum die casting or the like. In FIG. 1, the electrical operation and effect of the noise filter module 1 will be described.

  The switching power supply 5 is, for example, a vehicle-mounted power supply. It is a step-down type switching power supply that lowers the voltage value from a main battery (not shown) that supplies a power supply voltage VIN of a drive system in a hybrid vehicle or an electric vehicle to supply power to an auxiliary battery (not shown). The auxiliary battery supplies power supply voltage to in-vehicle electrical equipment such as audio equipment, air conditioner equipment, and lighting equipment.

  The switching power supply 5 obtains an output of a predetermined voltage by controlling on / off of a power transistor (not shown) at a predetermined switching frequency f. In the switching power supply 5, in accordance with the switching operation, a voltage fluctuation alternately occurs between a high voltage and a low voltage at the switching frequency f depending on the internal connection. Further, a current according to the load current is alternately intermittently connected to the power supply voltage VIN and the ground potential GND, and a flow current fluctuation occurs. The voltage fluctuation and the current fluctuation due to the switching operation may become a noise source and cause noise to the output terminal.

  Such a noise source may propagate to the output terminal as conduction noise that sneak through a signal path or a ground wiring, and may propagate to the output terminal as radiation noise radiated by electromagnetic coupling such as capacitive coupling or inductive coupling. Here, the radiation noise may occur, for example, in accordance with the voltage fluctuation of the internal connection. This is a case where an unexpected voltage fluctuation is caused to the circuit element of the coupling destination in response to the capacitive coupling due to the parasitic capacitance component existing between the circuit elements or between the wirings. In addition, it may occur due to current fluctuations in the power supply voltage VIN and the ground potential GND. This is a case where an unexpected voltage fluctuation is caused in the power supply voltage VIN and the ground potential GND according to the counter electromotive force due to the parasitic inductive component interposed in the wiring path of the power supply voltage VIN and the ground potential GND to be wired.

  The noise filter module 1 is connected to the output terminal VX of the switching power supply 5. In the noise filter module 1, the choke coil L1 is provided in the output voltage path connecting the output terminal VX and the output terminal VO of the switching power supply 5, and the capacitor C1 is provided between the output terminal VX of the switching power supply 5 and the ground potential GND. The capacitor C2 is connected between the output terminal VO and the ground potential GND. This is a so-called CLC type (π type) filter configuration. The capacitors C1 and C2 are mounted on the component surface of the mounting board 7. The surface of the mounting substrate 7 opposite to the component surface is a ground surface and is connected to the ground potential GND. One end of each of the capacitors C1 and C2 is connected to the ground plane and is connected to the ground potential GND. The noise filter module 1 can suppress the noise of the switching frequency f propagating in the signal path and the harmonic frequency thereof among the conduction noise. Here, the switching frequency f in the switching power supply 5 is determined according to the output power rating, the specifications and ratings of each component, and the like. For example, a vehicle-mounted switching power supply may operate at several 100 kHz. For this reason, the switching frequency f and its harmonic frequency may overlap with the frequency band of the in-vehicle AM radio, and by providing the noise filter module 1, it is possible to suppress conduction noise propagating in the signal path in these bands. it can.

  The switching power supply 5 and the noise filter module 1 are housed in a metal housing 3 made of aluminum die casting or the like. As a result, the metal casing 3 exerts an electromagnetic shielding effect, so that the radiation noise generated by the switching operation in the metal casing 3 is suppressed from propagating to the output terminal VO.

  Further, since the ground surface of the mounting substrate 7 is connected to the ground potential GND, the ground surface has an electromagnetic shielding effect, so that the radiation noise generated by the switching operation in the metal housing 3 causes the component surface. Propagation to the capacitors C1 and C2 mounted on is suppressed. As a result, the performance of the noise filter module 1 as a filter can be sufficiently exhibited.

  Next, the shape / structure that is the module configuration of the noise filter module 1 will be described. FIG. 2 is an exploded perspective view of the noise filter module 1. FIG. 3 is a perspective view of the noise filter module 1 in a molded state. FIG. 4 is a top view of the noise filter module 1 as seen from above in a molded state.

  The output voltage path connecting the output terminal VX and the output terminal VO of the switching power supply 5 shown in FIG. The conductive bar 11 has a substantially flat plate shape and a laterally elongated shape extending in the direction of the output terminal VX and the output terminal VO of the switching power supply 5, and is formed of a metal material such as copper or carbon steel. Bolt portions 11a, 11a are formed at both ends on the outer side in the extending direction with the central portion 11b interposed therebetween. A bolt hole 11c for connecting to the output terminal VX of the switching power supply 5 is connected to one bolt portion 11a (left side in FIG. 2), and an output terminal VO is connected to the other bolt portion 11a (right side in FIG. 2). A bolt hole 11d is provided for this purpose. That is, one bolt portion 11a is connected to the output terminal VX of the switching power supply 5 by using the bolt hole 11c, and the other bolt portion 11a is the output terminal VO, which is connected to the subsequent electronic device or the like by using the bolt hole 11d. To be done. The bolt portions 11a, 11a and the central portion 11b are arranged in the same straight line, and the conductive bar 11 is formed of a single metal member. The central portion 11b is slightly narrower in the width direction than the bolt portions 11a, 11a, and the magnetic core 13 is arranged at the center of the central portion 11b so as to be penetrated by the conductive bar 11.

  The magnetic core 13 is formed in a substantially rectangular parallelepiped shape having a hollow portion 13a, and is made of a magnetic material such as ferrite. In addition, a slit 13b is formed so as to penetrate through the conductive bar 11 in parallel with the extending direction of the conductive bar 11, and a part of the path that circulates in the circumferential direction with respect to the central portion 11b of the conductive bar 11 is discontinuous. ing. This is a so-called core gap, and the magnetic resistance in the magnetic core 13 is adjusted to prevent the occurrence of magnetic saturation. The conductive bar 11 penetrates the hollow portion 13a of the magnetic core 13, and the inner side surface of the hollow portion 13a and the central portion 11b of the conductive bar 11 are arranged to face each other, whereby the choke coil L1 is formed. By adjusting the width of the slit 13b, the magnetic resistance is adjusted to suppress magnetic saturation, and the inductance of the choke coil L1 required for removing noise components is secured.

  Here, the extending direction of the conductive bar 11 corresponds to the penetrating direction that penetrates the magnetic core 13.

  Electromagnetic shield plates 14, 14 are arranged on both end surfaces of the magnetic core 13 in the penetrating direction. The electromagnetic shielding plates 14 and 14 are formed in a flat plate shape having substantially the same shape as both end surfaces of the magnetic core 13 in the penetrating direction, and the conductive bar 11 penetrates like the magnetic core 13. The electromagnetic shielding plates 14 and 14 are formed of a conductive metal material such as copper, nickel, or iron, or formed of a conductive paint or a conductive polymer film containing powder or foil of the metal material. There is. The electromagnetic shielding plate 14 has an effect of electrically shielding the conductive bar 11 penetrating the hollow portion 13 a of the magnetic core 13. This has the effect of suppressing the propagation of radiation noise propagating from the conductive bar 11 to the outside. At the same time, the radiation noise propagating from the outside to the conductive bar 11 can be suppressed. Although the electromagnetic shield plates 14 are provided on both end faces of the magnetic core 13 in the present embodiment, they may be provided on one end face.

  The conductive bar 11 and the magnetic core 13 (including the electromagnetic shielding plates 14 and 14) configured as described above are molded by the lower mold part 32 and the upper mold part 31 as shown in FIG. Specifically, the magnetic core 13 part (including the electromagnetic shielding plates 14 and 14) is located in the central recess 32e of the lower mold part 32, and the central part 11b of the conductive bar 11 penetrating the magnetic core 13 part is at both ends. The conductive bar 11 and the magnetic core 13 (including the electromagnetic shielding plates 14 and 14) are disposed in the concave portions 32c and 32d of the mold and sandwiched between the mold lower portion 32 and the mold upper portion 31 from the mold lower portion 32 and the mold upper portion 31. It is fixed in the mold part.

  The mounting substrate 7 is arranged on the upper surface above the mold upper portion 31. The mounting board 7 has a component surface on which the capacitor 22 (C1) and the capacitor 23 (C2) are mounted and a ground surface on the surface opposite to the component surface. As shown in FIG. Attached to the upper mold part 31. A rectangular through hole 7e is provided in the substantially central portion of the mounting substrate 7, and the mounting substrate 7 is positioned by fitting with a square columnar convex portion 31a provided on the upper surface of the mold upper portion 31. Further, the mounting board 7 is provided with square pattern holes 7a, 7b, 7c and 7d. The pattern hole 7a is connected to one of the electrodes of the capacitor 22 on the component side by a conductive pattern, the pattern hole 7b is connected to one of the electrodes of the capacitor 23 on the component surface by a conductive pattern, and the pattern hole 7c is connected to the component 22 of the capacitor 22. It is connected to the other of the electrodes by a conductive pattern and is also connected to the ground pattern on the ground surface, and the pattern hole 7d is connected to the other of the electrodes of the capacitor 23 on the component surface by the conductive pattern, and at the same time, is grounded on the ground surface. It is also connected to the pattern. The pattern holes 7a, 7b, 7c and 7d are through holes for joining lead members by soldering or the like as described below.

  Further, the lead members 15, 17, 19 and 21 are attached to the upper part 31 of the mold. The lead members 15, 17, 19 and 21 are made of a conductive metal material such as copper, nickel, or iron, and the pattern holes 7a, 7b, 7c of the mounting board 7 are formed at the upper ends of the lead members. Fitting portions 15a, 17a, 19a, and 21a that fit into and 7d are provided. The fitting portion 15a of the lead member 15 is a pattern hole 7a of the mounting board 7, the fitting portion 17a of the lead member 17 is a pattern hole 7b of the mounting board 7, and the fitting portion 19a of the lead member 19 is a pattern of the mounting board 7. The hole 7c and the fitting portion 21a of the lead member 21 are fitted into the pattern hole 7d of the mounting board 7, respectively. After fitting, they are joined by soldering or the like.

  A male screw 15b (not shown) and a male screw 17b are fixed to the lower ends of the lead members 15 and 17, respectively. , And the male screw 15b and the male screw 17b are tightened from below the conductive bar 11 with a nut (not shown) which is a female screw. As a result, the lead member 15 is fixedly connected to one bolt portion 11a (left side in FIG. 2) connected to the output terminal VX of the switching power supply 5, and the lead member 17 is the other bolt that is the output terminal VO. It is fixed and connected to the portion 11a (right side in FIG. 2). The method of connecting the lower end portions of the lead members 15 and 17 and the bolt portions 11a and 11a of the conductive bar 11 is not limited to using screws and nuts. For example, when the male screw 15b and the male screw 17b are bolts. While penetrating the holes 11e and 11f, they may be fixed by soldering for connection, or resistance welding may be used.

  In addition, circular through holes 19b and 21b are provided at the lower ends of the lead members 19 and 21. Then, the mold lower portion 32 is provided with circular through holes 32a and 32b having a hole diameter substantially the same as the hole diameters of the through holes 19b and 21b. In the state where the lower mold part 32 and the upper mold part 31 are joined, the through hole 19b of the lead member 19 is arranged concentrically with the through hole 32a of the lower mold part 32, and the through hole 21b of the lead member 21 is the through hole of the lower mold part 32. It is arranged concentrically with 32b. The through hole 32a and the through hole 32b of the lower part 32 of the mold are mounting holes for mounting the noise filter module 1 in the metal housing 3 in which the noise filter module 1 and the switching power supply 5 are housed, and are mounted with metal bolts or the like. As a result, the lower ends of the lead members 19 and 21 are connected to the metal housing 3.

  As described above, the noise filter module 1 is arranged between the output terminal VX and the output terminal VO of the switching power supply 5, and is housed in the metal housing 3 together with the switching power supply 5. The choke coil L1 including the conductive bar 11 and the magnetic core 13 is connected between the output terminal VX and the output terminal VO of the switching power supply 5. In addition, a capacitor 22 is provided between the output terminal VX of the switching power supply 5 connected to one of the bolt portions 11a of the conductive bar 11 via the lead member 15 and the lead member 19 and the metal housing 3 at the ground potential GND. A capacitor 23 is connected between the output terminal VO, which is the other bolt portion 11a of the conductive bar 11, and the metal housing 3 that is at the ground potential GND via the lead member 17 and the lead member 21. As a result, the noise filter module 1 is configured as a CLC type (π type) filter.

  Since the switching power supply 5 and the noise filter module 1 are both housed in the metal casing 3, it is possible to suppress the radiation noise generated by the switching operation of the switching power supply 5 from propagating to the output terminal VO. Further, since the capacitors 22 and 23 are shielded by the ground surface of the mounting board 7, the capacitors 22 and 23 are suppressed from being exposed to the radiation noise generated in the metal housing 3, and the filter of the noise filter module 1 is suppressed. As a result, it can fully exhibit its performance.

  Next, the noise filter module 1a which is the output noise reduction device according to the second embodiment will be described with reference to FIG. 5A is a plan view of the noise filter module 1a as seen from above, FIG. 5B is a front view as seen from the lead member 25, and FIG. 5C is a side view as seen from the lead member 17. FIG. 5 (D) shows a perspective view. The circuit diagram of the noise filter module 1a is the same as that of the first embodiment, and will not be described here.

  The conductive bar 11, the magnetic core 13 (including the electromagnetic shielding plates 14 and 14), the mounting board 7, the lead member 15 and the lead member 17 are the same as those in the first embodiment. The conductive bar 11 and the magnetic core 13 (including the electromagnetic shielding plates 14 and 14) are molded in the same manner as in the first embodiment by using the mold member 26 instead of the mold upper portion 31 and the mold lower portion 32 of the first embodiment. ing. The lead member 25 is used instead of the lead member 19 of the first embodiment, and the lead member 24 is used instead of the lead member 21 of the first embodiment. Like the lead members 15 and 17, the lead members 24 and 25 are made of a conductive metal material such as copper, nickel, or iron. The circular through holes 24a and 25a provided at the lower ends of the lead members 24 and 25 are mounting holes for mounting the noise filter module 1a to the metal housing 3, and the mounting substrate is mounted via the lead members 24 and 25. The ground surface of 7 is connected to the metal housing 3 and grounded.

  As shown in FIG. 5, the lead members 24 and 25 are formed of a flat plate that is wide in the extending direction of the conductive bar 11, and the width thereof is the width of the side surface of the molding member 26 or the width (length of the side surface of the mounting substrate 7). ) Is almost the same width. When the noise filter module 1 a is attached to the metal housing 3, the lower ends of the lead members 24 and 25 are connected to the metal housing 3. As a result, the lead members 24 and 25 shield the choke coil L1 formed of the conductive bar 11 and the magnetic core 13 and both sides of the capacitors 22 and 23 mounted on the mounting surface of the mounting substrate 7. Further, the upper surfaces of the capacitors 22 and 23 mounted on the mounting surfaces of the choke coil L1 and the mounting board 7 are shielded by the ground surface of the mounting board 7, and the lower surfaces are shielded by the metal housing 3. As described above, since the noise filter module 1a according to the second embodiment shields the entire CLC type (π type) filter including the choke coil L1 and the capacitors 22 and 23 vertically and horizontally, it is generated in the metal housing 3. Radiated noise is further suppressed, and the performance of the noise filter module 1a as a filter can be sufficiently exerted.

  Next, the noise filter module 1b which is the output noise reduction device according to the third embodiment will be described with reference to FIG. 6A is a plan view of the noise filter module 1b as seen from above, FIG. 6B is a front view as seen from the lead member 35, and FIG. 6C is a side view as seen from the lead member 34. FIG. 6D shows a perspective view. Since the circuit diagram of the noise filter module 1b is also the same as that of the first embodiment, its details will not be described here.

  The conductive bar 11, the magnetic core 13 (including the electromagnetic shields 14 and 14), and the mounting board 7 are the same as those in the first embodiment. The molding member 26 for molding the conductive bar 11 and the magnetic core 13 (including the electromagnetic shielding plates 14 and 14) is the same as in the second embodiment. A lead member 33 is used instead of the lead member 15 of the first embodiment, a lead member 34 is used instead of the lead member 17 of the first embodiment, and a lead member 35 is used instead of the lead member 19 of the first embodiment. The lead member 36 is used instead of the lead member 21 of the embodiment. The lead members 33, 34, 35, and 36 are formed of a conductive metal material such as copper, nickel, or iron, as in the first embodiment. The circular through holes 35a and 36a provided at the lower end portions of the lead members 35 and 36 are mounting holes for mounting the noise filter module 1b on the metal housing 3, and the mounting substrate is mounted via the lead members 35 and 36. The ground surface of 7 is connected to the metal housing 3 and grounded.

  In the noise filter module 1b, the mounting substrate 7 is arranged on the lower surface of the molding member 26 with the ground surface facing upward. The lead members 35 and 36 are formed with a height such that the capacitors 22 and 23 mounted on the mounting surface of the mounting substrate 7 do not contact the metal housing 3 when the noise filter module 1b is mounted on the metal housing 3. ing.

  With such a configuration, the capacitors 22 and 23 mounted on the mounting surface of the mounting board 7 are shielded by the ground surface of the mounting board 7 in the upper part and shielded by the metal housing 3 in the lower part. Thereby, the radiation noise generated in the metal housing 3 with respect to the capacitors 22 and 23 is suppressed, and the performance of the noise filter module 1b as a filter can be sufficiently exhibited.

  Further, in the third embodiment, a recess may be provided in the metal casing 3 so that the capacitors 22 and 23 mounted on the mounting surface of the mounting board 7 can be accommodated in the recess. As a result, the capacitors 22 and 23 mounted on the mounting surface of the mounting board 7 are shielded not only by the metal casing 3 but also in the side direction, so that the radiation noise can be further suppressed.

  Here, the switching power supply 5 is an example of an electronic device, the noise filter modules 1, 1a and 1b are examples of an output noise reduction device, the conductive bar 11 is an example of a conductive bar, and the magnetic core 13 is a magnetic body. The mounting board 7 is an example of a mounting board, the capacitors 22 and 23 are an example of capacitive elements, the lead members 19, 21, 24, 25, and 3536 are examples of a connecting member, and the ground plane is an example. It is an example of a metal surface, and the metal housing 3 is an example of a metal housing.

  Although the embodiments of the present invention have been described above in detail, these are merely examples, and the present invention should not be construed as being limited to the specific description of the embodiments, and those skilled in the art will understand. The present invention can be carried out in a mode in which various changes, modifications, improvements, etc. are added based on knowledge, and all such embodiments are within the scope of the present invention as long as such an embodiment does not depart from the gist of the present invention. It should be understood that it is included in.

  For example, although the noise filter module is a CLC type (π type) noise filter in the above embodiment, an LC type (L type) noise filter may be adopted depending on the conduction noise propagating in the signal path.

  Further, in the above-described embodiment, the conductive bar 11 and the magnetic core 13 which form the choke coil are molded by the molding member, but if the conductive bar 11 and the magnetic core 13 can be arranged insulated from other conductive members, they are necessarily molded. No need.

1, 1a, 1b ··· Noise filter module 3 · · Metal housing 5 · · Switching power supply 7 · · Mounting board 11 · · Conducting bar 13 · · Magnetic core 15, 17, 19, 21, 24, 25, 33 , 34, 35, 36 ... Lead members 22, 23. Capacitor 31. Mold upper part 32. Mold lower part

Claims (5)

An output noise reduction device for reducing noise mixed in an output signal from an electronic device,
A metal housing that houses the electronic device and the output noise reduction device;
A conductive bar formed of a conductive material, one end of which is a connection terminal for connecting to an output end of the electronic device, and the other end of which is an output terminal,
A magnetic core formed of a magnetic material, having a through hole through which the conductive bar penetrates;
Between the magnetic core and the output terminal or between at least one of the magnetic core and the connection terminal, a capacitive element for connecting between the conductive bar and the metal housing,
One surface is a mounting surface for mounting the capacitive element, and the other surface is provided with a mounting substrate to which one terminal of the capacitive element is connected and which is a metal surface having the same potential as the metal housing. Output noise reduction device.   The output noise reduction device according to claim 1, wherein the conductive bar and the magnetic core except the connection terminal and the output terminal are molded by a molding member formed of a resin material.   The output noise reduction device according to claim 1, wherein the mounting substrate is arranged such that the mounting faces the magnetic core.   A flat plate-shaped member that connects the metal surface of the mounting substrate to the metal housing, and includes a connection member that is parallel to the conductive bar and covers at least one of the magnetic core and the conductive bar. The output noise reduction device according to claim 3, wherein   3. The output noise reduction device according to claim 1, wherein the mounting substrate is sandwiched between the magnetic core and the metal housing with the mounting surface facing the metal housing. ..

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