JP2002324630A - Electronic device and power supply plug - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an electronic device and power supply plug with a big noise suppression effect at high-frequency band, and enabled to reduce the size and cost. SOLUTION: A commercial alternating current power source line 60 connected to a power supply plug 51 is connected to a switching power source 51 through two inductors, filter circuit 53, and coils L1, L2, and connected further to a load circuit 56. The inductor 30 is composed of a solenoid coil embedded in magnetic material. The synthetic resin molding, for example, made of epoxy resin, polyphenylene sulfide, or polyethylene terephthalate, as a main component, including Ni-Cu-Zn group ferrite powder by 30-90 weight %, or a material, made by burning a slurry formed by kneading the mixture of magnetic ceramics powder and binder, is used as the magnetic material.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electronic device and a power outlet, and more particularly, to an electronic device having a commercial AC power line and a power outlet of the commercial AC power line.

[0002]

2. Description of the Related Art In general, switching power supplies are the most frequently used power supply devices because they are efficient and can be miniaturized. However, a switching power supply uses a method of once rectifying a commercial AC current, performing switching while controlling the rectification, and rectifying the commercial AC current. Therefore, in each of these steps, a distorted wave containing a large number of harmonic components over a wide frequency band is used. When a digital circuit or the like including a high-frequency component is connected to the load, a noise component flows out through the switching power supply device to the outside. For this reason, unless countermeasures are taken against noise in a wide band from the KHz band to the GHz band, there arise problems such as those harmonics flowing back to the AC power supply line as noise and radiating outside.

[0003] In addition, the switching power supply alone can take measures against noise to achieve a level that satisfies the noise regulation standard value.
As soon as a load with a high noise level such as a digital circuit is connected to the switching power supply, noise may be radiated from the switching power supply or the commercial AC power supply line. This is because the switching power supply becomes a path for noise. To solve such a problem,
It is necessary to connect a noise filter capable of covering an expected frequency band to the primary side or the secondary side of the switching power supply. Further, since a large current flows through the commercial AC power supply line, a noise filter having a good current superposition characteristic is required.

FIG. 12 shows an example of a conventional noise countermeasure for an electronic device 50 having a switching power supply 55. The commercial AC power supply line 60 connected to the outlet 51 is connected to the switching power supply 55 via the filter circuit 53 and the coils L1 and L2 after being bifilar wound around the ferrite ring core 52, and further connected to the load circuit 56. I have.

The ferrite ring core 52 functions as a common mode choke coil when the commercial AC power supply line 60 is wound, and removes high frequency band common mode noise. This ferrite ring core 52
Since the commercial AC power supply line 60 is wound, a core having a large size is used and current superimposition characteristics are secured. Then, the filter circuit 53 removes the common mode noise in the middle and low frequency bands. This filter circuit 53
It is composed of three capacitors C1 to C3 and one common mode choke coil 54, and has good current superposition characteristics. On the other hand, the coils L1 and L2 remove normal mode noise.

[0006]

However, when the ferrite ring core 52 is used, there are various problems as described below.

(1) Since the size is large, it is necessary to secure a wide mounting space. (2) The work of winding the commercial AC power supply line 60 around the ferrite ring core 52 is complicated.

(3) When mounting on a printed circuit board or the like,
A fixing method different from that of other chip components must be adopted, and a special fixing member is also required, so that the mounting cost is high.

(4) Since the primary AC voltage is applied, when the commercial AC power supply line 60 is wound around the ferrite ring core 52 from the viewpoint of safety such as insulation assurance and withstand voltage assurance, the AC power supply line 60 It is necessary to secure a sufficient distance between the ferrite ring core 52 and the large and expensive ferrite ring core 52.
Must be used.

(5) The impedance in a high frequency band (particularly, a band of 100 MHz or more) is low, and almost no normal mode impedance can be obtained. Therefore, the noise suppression effect in the high frequency band is not sufficient.

SUMMARY OF THE INVENTION An object of the present invention is to provide an electronic device and a power outlet which have a large noise suppressing effect in a high frequency band and which can be reduced in size and cost.

[0012]

In order to achieve the above object, an electronic apparatus according to the present invention comprises an inductor in which a coil formed by winding a metal wire is buried in a magnetic material, and which is connected to a commercial AC power supply line. It is characterized by the fact that the connection is made. As the magnetic body, for example, a resin molded body containing magnetic powder or a ceramic sintered molded body is used.

A power outlet according to the present invention includes an insulating housing, an inductor built in the insulating housing, and a first metal terminal electrically connected to one external terminal electrode of the inductor. A second metal terminal electrically connected to the other external terminal electrode of the inductor, wherein the inductor embeds a coil formed by winding a metal wire in a magnetic body, and connects both ends of the coil to each other. It is an inductor connected to the external terminal electrode. The magnetic body is, for example, a ceramic sintered compact,
Alternatively, it is made of a resin molded body containing magnetic powder.

With the above configuration, the effect of removing noise in a high frequency band is increased as compared with the case where a ferrite ring core is used.

When using an inductor in which a coil formed by winding a metal wire is embedded in a magnetic material, it is necessary to connect at least two inductors to a commercial AC power supply line. However, unlike the conventional configuration in which the commercial AC power line is wound around a ferrite ring core, the primary side voltage is not applied to the inductor, so it is necessary to secure a distance between the commercial AC power lines in terms of safety such as withstanding voltage. Because of this, a small and inexpensive inductor can be used, and the mounting space is small.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of an electronic device and a power outlet according to the present invention will be described below with reference to the accompanying drawings.

[First Embodiment, FIGS. 1 to 5] FIG. 1 is an electric circuit block diagram of an AC power supply line of an electronic apparatus (for example, a personal computer) 1 having a switching power supply. The commercial AC power supply line 60 connected to the outlet 51 has two inductors 30 and a filter circuit 53.
And the switching power supply 55 via the coils L1 and L2, and further connected to the load circuit 56.

As shown in FIG. 2, the switching power supply 55 is a well-known type including a primary rectifier circuit 2, a switching circuit 3, a secondary rectifier circuit 4, and a control circuit 5. The primary rectifier circuit 2 includes four diodes D1 to D4 and one capacitor C11. Switching circuit 3
Is composed of a primary transformer L11 and a transistor Tr. The secondary rectifier circuit 4 includes a secondary transformer L12
And two diodes D5 and D6, a coil L13 and a capacitor C12, and has a capacitor input smoothing circuit including a diode D5 and a capacitor C12.

The filter circuit 53 removes common mode noise in the middle and low frequency bands and normal mode noise in the middle and low frequency bands. The filter circuit 53 includes three capacitors C1 to C3 and one common mode choke coil 5
4 and has good current superposition characteristics. On the other hand, the coils L1 and L2 remove normal mode noise.

As shown in FIG. 3, the inductor 30 has a solenoidal coil (air-core coil) 10 embedded in a magnetic body 15. Solenoid part 1 of coil 10
The outside and inside of 1 are filled with a magnetic body 15.
External terminal electrodes 21 and 22 are formed on both ends of the magnetic body 15 in a state of being electrically connected to the coil 10.

The solenoid coil 10 is formed by densely winding (single-layer aligned winding) a metal wire covered with an insulating film. Both ends of the solenoid-shaped coil 10 are linear drawers 12 respectively. For metal wires,
For example, a metal wire or an alloy wire containing one or more of Ag, Pd, Pt, Au, Cu, and Al is used.
As a material of the insulating film, for example, a resin such as polyester or polyamide imide is used.

In the present embodiment, a desired (50
(Ω or more) is formed by winding a single-layer solenoid coil 10 having an impedance of Ω or more. This is because the stray capacitance generated in parallel with the coil 10 is suppressed, and the noise removal capability in the high frequency band is not reduced. Incidentally, when the coil 10 has a multilayer winding structure (for example, after the first layer is aligned and wound from left to right, then the second layer is aligned and wound from right to left on the first layer) Since a part of the solenoid portion 11 of the coil 10 approaches the external terminal electrode 21 (or 22) on the opposite side where the voltage difference is large, the stray capacitance generated between the external terminal electrodes 21 and 22 and the coil 10 increases. Also, between the upper and lower layers adjacent to the solenoid portion 11, a large stray capacitance is generated at the winding portion where the voltage difference is large.

As the magnetic body 15, for example, a synthetic resin molded body containing epoxy, polyphenylene sulfide, or polyethylene terephthalate as a main component and containing 30 to 90% by weight of a Ni-Cu-Zn ferrite powder is used. . When the content of the ferrite powder is 85% by weight, the initial magnetic permeability μ of the inductor 30 becomes about 12, and a sufficient noise removing ability can be obtained even with a small size. However, when the content of the ferrite powder is less than 30% by weight,
The initial permeability μ of the inductor 30 becomes about 2 to 3, and the inductance value decreases. Therefore, in order to obtain a sufficient noise removal capability, the inductor 30 needs to have a very large size, which is not suitable for practical use. Conversely, if the content of the ferrite powder is more than 90% by weight, the current superimposition characteristics of the inductor 30 deteriorate, and the inductor 30 is not suitable for a noise filter for a commercial AC power supply line. In addition,
The magnetic body 15 may be made of a ceramic sintered compact.

The electronic device 1 having the above-described configuration uses the inductor 30 in which the solenoidal coil 10 is embedded in the magnetic body 15 instead of the ferrite ring core. The size can be increased as compared with the case where a ring core is used. FIG. 4 shows an AC power supply line 60 of the electronic device 1.
Shows the result of measuring the common mode noise current flowing through (see solid line 35). In the graph shown in FIG. 4, the noise current is converted into a voltage and displayed. FIG. 4 shows, for comparison, a common mode noise current when the inductor 30 is removed (see a dashed line 36) and a common mode noise current when a ferrite ring core is attached instead of the inductor 30 (see a dotted line 37). Are also shown.

FIG. 4 shows that the electronic device 1 to which the inductor 30 is attached is excellent in reducing radiation noise particularly in a high-frequency band of 100 to 150 MHz. As can be seen from the frequency-impedance curve 38 of the inductor 30 and the frequency-impedance curve 39 of the ferrite ring core shown in FIG. 5, the impedance of the inductor 30 becomes larger than the impedance of the ferrite ring core on the high frequency side from around 100 MHz. Because.

When a ferrite ring core is used, a voltage on the primary side is applied to the ferrite ring core.
When winding 0 on the ferrite ring core, it is necessary to secure a sufficient distance between the commercial AC power supply lines 60, and a covered wire covered with a thick insulator or an insulating cover covering the ferrite ring core is required. Necessary and large (typical example: diameter = 21.5 mm, thickness = 13.0 mm)
The expensive ferrite ring core had to be used. On the other hand, when the inductor 30 is used, the primary-side voltage is not applied to the inductor 30 itself, which is excellent in safety. In addition, the inductor 30 is small (representative example: length = 4.5 mm, width = 3.2 mm, height = 3.3 mm).
2 mm), the space for mounting may be about 1/50 of the ferrite ring core even when the two inductors 30 are connected to the commercial AC power supply line 60, and the electronic device 1 can be downsized. it can.

Further, when the inductor 30 is used, the operation of winding the commercial AC power supply line 60 around the ferrite ring core can be omitted. In addition, when the inductor 30 is mounted on a printed circuit board or the like, it can be mounted using an automatic surface mounter similarly to other chip components, so that mounting cost can be reduced.

It is preferable that the capacitor input smoothing circuit of the secondary rectifier circuit 4 of the switching power supply 55 has a non-conduction time of 50% or more. High frequency noise is generated irregularly regardless of whether the capacitor input smoothing circuit is energized or deenergized. It is preferable that the inductor 30 not be magnetically saturated by the supplied current. However, even if a large current flows when the capacitor input smoothing circuit is energized and the inductor 30 is magnetically saturated and the noise removing effect is lost, the noise removing effect is obtained when the inductor is not energized. Because it is effective, it is averaged up to about 6
This is because the noise reduction effect of dB (half) can be suppressed.

[Second Embodiment, FIGS. 6 and 7] An electronic apparatus according to a second embodiment differs from the first embodiment in FIG.
This is the same as the one using an inductor made of a ceramic sintered compact (hereinafter referred to as a ceramic sintered inductor) instead of the inductor 30 made of a synthetic resin molded body containing ferrite powder.

The structure of the ceramic sintered inductor is shown in FIG.
Is the same as the inductor 30 shown in FIG. This inductor is manufactured, for example, as follows. A slurry in which the magnetic ceramic powder is kneaded together with a binder and the like is poured into a molding die in which the solenoidal coil 10 is arranged, thereby producing a sealed molded body incorporating the solenoidal coil 10. Next, after baking this sealing molded body to obtain a magnetic body (ceramic sintered molded body) 15, external terminal electrodes 21 and 22 are formed on both ends thereof.

The electronic device 1 having the ceramic sintered inductor has the same functions and effects as those of the electronic device of the first embodiment. That is, a high frequency band (especially 100 to 15)
The noise removal effect at around 0 MHz) can be increased as compared with the case where a ferrite ring core is used. FIG. 6 shows the result of measuring the common mode noise current of the AC power supply line 60 of the electronic device 1 (see the solid line 45). FIG. 6 shows, for comparison, the common mode noise current when the ceramic sintered inductor was removed (see the dashed line 46) and the common mode noise current when the ferrite ring core was used (see the dotted line 47). The results are also shown.

FIG. 6 shows that the electronic device 1 to which the inductor 30 is attached is excellent in reducing radiation noise particularly in a high-frequency band of 100 to 150 MHz. As can be seen from the frequency-impedance curve 40 of the inductor 30 and the frequency-impedance curve 41 of the ferrite ring core shown in FIG. 7, the impedance of the inductor 30 becomes larger than the impedance of the ferrite ring core on the high frequency side from around 100 MHz. Because.

The ceramic sintered inductor is small (typical example: length = 3.2 mm, width = 2.5 mm, height =
2.5 mm), even if two ceramic sintered inductors are connected to the commercial AC power supply line 60, the space for mounting is about 1/11 of that of the ferrite ring core.
0, and the size of the electronic device 1 can be reduced.

[Third Embodiment, FIGS. 8 to 11] As shown in FIG. 8, an electronic device 1A according to a third embodiment
8, a device-side outlet 71 is attached, and a power cord-side outlet 70 connected to one end of a commercial AC power cord 60a is inserted into the device-side outlet 71.
The other end of the power cord 60a is connected to the outlet 51.

The device-side outlet 71 has a lead wire 60
One end of b is soldered. The other end of the lead wire 60b is soldered to a printed circuit board 57 provided inside the device housing 58, and the filter circuit 53 and the normal mode choke coils L1, L on the printed circuit board 57 are provided.
2 is electrically connected to a switching power supply.

The device-side outlet 71 is shown in FIGS.
As shown in FIG. 5, the insulating housing 72 includes two inductors 73 built in the insulating housing 72, two first metal terminals 81 and second metal terminals 82, and a ground metal terminal 83, respectively. I have. The insulating housing 72 is a plastic case made of an insulating material such as a phenol resin.

The inductor 73 is similar to the inductor 30 shown in FIG. 3, and has a solenoidal coil (air-core coil) 10 embedded in a magnetic body 15. External terminal electrodes 74 and 75 are formed on both ends of the magnetic body 15 in a state of being electrically connected to the coil 10. In the third embodiment, a copper wire having a diameter of 0.2 mm is used, and the inner diameter of the solenoid portion 11 is 1.8 mm, and the length of the solenoid portion 11 is 3.2 mm.
Was formed. Further, as the magnetic body 15, a ferrite resin having an initial magnetic permeability μ of 10 to 20, which is obtained by adding a Ni—Cu—Zn-based ferrite powder to a polyphenylene sulfide resin, was used. The size of the inductor 73 is length =
4.5 mm, width = 3.2 mm, height = 3.2 mm.

FIG. 11 is a graph showing superimposed current characteristics of the inductor 73 at 100 MHz. The inductor 73 has an impedance of 500Ω or more at a frequency of 100 MHz when a DC current of 2 A (rated current value) is applied.

As shown in FIG. 10, the first and second metal terminals 81 and 82 are respectively connected to inductor connection parts 81b and 82b arranged horizontally and a lead-out part 81 arranged vertically.
a, 82a. The inductor connecting portions 81b and 82b of the first and second metal terminals 81 and 82 have
The external terminal electrodes 74 and 75 of the inductor 73 are connected by soldering. The first and second metal terminals 81 and 82 to which the inductor 73 is soldered are housed together with the ground metal terminal 83 in the insulating housing 72 with an insulation distance therebetween.

As shown in FIG. 9, the lead-out portions 81a and 83a of the metal terminals 81 and 83 project from a concave portion 72a formed on the front surface of the insulating housing 72. The outlets 81a and 83a are connected to the power cord-side outlet 70. On the other hand, the lead portions 82a, 8 of the metal terminals 82, 83
3b protrudes from the back surface of the insulating housing 72. The lead wire 60b routed from the printed board 57 is soldered to the lead-out portion 82a. Derivation unit 8
A ground wire 60c is soldered to 3b. If necessary, the insulating housing 72 may be filled with a resin or the like having excellent insulating properties.

The device-side outlet 71 having the above configuration
Uses an inductor 73 in which the solenoidal coil 10 is embedded in a magnetic body 15 made of a resin containing a magnetic substance powder without using an inductor of a type in which a metal wire is wound around a ferrite core. Even when the rated current flows, magnetic saturation does not easily occur, and the impedance in a high frequency band becomes high. Therefore, the device side outlet 7
No. 1 can increase the noise removal effect in the high frequency band as compared with the case where a ferrite core is used in which a metal wire is wound around a ferrite core.

Table 1 shows the power cord 60a of the electronic device 1A.
5 shows the results of measuring the common mode noise current flowing through. However, the electronic device 1A is a personal computer having a clock frequency of 33 MHz (power consumption: about 1
50 W) and the length of the power cord 60a was 150 cm. Table 1 also shows, for comparison, the results of measuring the common mode noise current when a conventional ferrite ring core was attached.

[0043]

[Table 1]

It can be seen from Table 1 that the use of the inductor 73 reduces the common mode noise current flowing through the power cord 60a by 10 dB or more. As a result, it is possible to obtain the device-side outlet 71 that exhibits an excellent effect of reducing radiation noise in a high-frequency band.

Since the inductor 73 is small,
Even when the two inductors 73 are accommodated in the device-side outlet 71, the size of the device-side outlet 71 is the same as that of the conventional device-side outlet, and does not require a new component space.

[Other Embodiments] The present invention is not limited to the above-described embodiment, and can be variously modified within the scope of the gist. In particular, in the above embodiment, the normal mode coils L1 and L2 are not always necessary, and can be omitted according to the specifications.

In the third embodiment, the device-side outlet 71 is of a male type, but may be of a female type.
Further, instead of incorporating the inductor 73 in the device-side outlet 71, the inductor 73 may be incorporated in the power cord-side outlet 70. In addition, when the electronic device 1A is provided with a power outlet for supplying power to another device, the present invention may be applied to the power outlet for supplying power. This allows
It is possible to suppress conducted noise to other devices or to suppress conducted noise from other devices.

[0048]

As apparent from the above description, according to the present invention, an inductor in which a coil formed by winding a metal wire is embedded in a magnetic material is electrically connected to a commercial AC power supply line. The noise removal effect in the high frequency band can be increased as compared with the case where a ferrite ring core is used. In addition, since the size of the inductor is reduced, the mounting space may be reduced, and the electronic device may be reduced in size and cost.

[Brief description of the drawings]

FIG. 1 is an electric circuit block diagram illustrating a first embodiment of an electronic apparatus according to the invention.

FIG. 2 is an electric circuit diagram showing a switching power supply used in the electronic device shown in FIG.

FIG. 3 is a partial cross-sectional view showing an inductor used in the electronic device shown in FIG.

FIG. 4 is a graph showing a noise level of the electronic device shown in FIG.

FIG. 5 is a graph showing frequency-impedance characteristics of each of the inductor and the ferrite ring core shown in FIG. 3;

FIG. 6 is a graph showing a noise level of a second embodiment of the electronic apparatus according to the invention.

FIG. 7 is a graph showing frequency-impedance characteristics of each of an inductor and a ferrite ring core according to a second embodiment.

FIG. 8 is an electric circuit block diagram illustrating a third embodiment of the electronic apparatus according to the invention.

FIG. 9 is a perspective view showing an example of a power outlet according to the present invention.

FIG. 10 is an exemplary perspective view showing the internal configuration of the power outlet shown in FIG. 9;

11 is a graph showing superimposed current characteristics of the inductor shown in FIG.

FIG. 12 is an electric circuit block diagram showing a conventional electronic device.

[Explanation of symbols]

 1, 1A: Electronic equipment 10: Solenoid coil 15: Magnetic body 30: Inductor 53: Filter circuit 55: Switching power supply 56: Load circuit 60: Commercial AC power supply line 71: Equipment side outlet (power outlet) 72: Insulating housing 73 ... Inductor 74,75 ... External terminal electrode 81 ... First metal terminal 82 ... Second metal terminal

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Masami Sugitani 2-26-10 Tenjin, Nagaokakyo-shi, Kyoto Inside Murata Manufacturing Co., Ltd. (72) Junichi Hamaya 2-26-10 Tenjin, Nagaokakyo-shi, Kyoto Stock Company Inside Murata Manufacturing Co., Ltd. (72) Inventor, Junto Oshima 2-26-10 Tenjin, Nagaokakyo-shi, Kyoto, Japan Inside Murata Manufacturing Co., Ltd. F term (reference) 5E021 FA03 FA10 FA14 FB03 FB13 FC02 FC12 FC13 FC14 FC19 KA13 MA09 MA13 MA14 MA18 MA19 MA27 MA30 MB01 MB03 5E321 AA31 AA32 BB32 BB51 GG05

Claims (5)

[Claims] 1. An electronic apparatus, wherein an inductor having a coil formed by winding a metal wire embedded in a magnetic material is electrically connected to a commercial AC power supply line. 2. The electronic device according to claim 1, wherein the magnetic body is a resin molded body containing magnetic powder. 3. The electronic device according to claim 1, wherein the magnetic material is a ceramic sintered compact. 4. An insulative housing, an inductor built in the insulative housing, and a first metal terminal electrically connected to one external terminal electrode of the inductor.
A second metal terminal electrically connected to the other external terminal electrode of the inductor, wherein the inductor embeds a coil formed by winding a metal wire in a magnetic material, and includes both ends of the coil. A power outlet, comprising: an inductor connected to the external terminal electrode. 5. The method according to claim 1, wherein the magnetic material is a ceramic sintered compact,
The power outlet according to claim 4, wherein the power outlet is made of any one of a resin molded body containing magnetic powder.