JP2014086479A - Electronic apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce EMC countermeasure member costs because in the prior art, gaps are filled with EMC countermeasure components such as metal fingers, but these EMC countermeasure components are not cheap at all, and in addition the length of the gaps, which will be radiation openings of noise, becomes larger in proportion to the size of an enclosure, and the number of the gaps exists as many as the number of PKGs + 1, which makes the usage amount of the EMC countermeasure components quite a few per device in current communication devices, and therefore the EMC countermeasure member costs become expensive.SOLUTION: Bringing into contact between protrusions 6 provided at front panels of adjacent units and an enclosure can prevent radiation of noise from a gap between the units.

Description

  The present invention relates to an electronic device, and more particularly, to an electronic device that requires EMC countermeasures and involves insertion / extraction of a printed circuit board unit with a metal casing.

  Electronic devices that handle high-speed digital signals typified by computers and communication devices emit unintentional electromagnetic waves (noise) with the operation of the devices. In order to prevent television and radio broadcasts and wireless communication facilities from being affected by this noise, laws, international standards, etc. require that the noise level be kept below the standard.

  In general electronic devices, in order to prevent such noise emission, the casing of the electronic device is made of metal, and has a noise shielding structure that does not create a gap serving as a noise emission port. However, the communication device is required to have a structure in which a plurality of printed circuit board units, a power supply unit, a hard disk unit, and the like can be inserted into and removed from an insertion port provided in the housing. For this reason, it is difficult for the communication device to cover the outside of the housing with a metal plate without a gap. That is, a gap is inevitably generated between adjacent units due to the structure.

  The structure of a general communication device will be described with reference to FIG. In FIG. 1, the communication device has a structure in which several types of PKGs 2 are inserted into a plurality of unit insertion ports provided in the housing 1. The PKG 2 is generally composed of a PCB (Printed Circuit Board) 5 and a front plate 3. The front plate 3 is a component whose cross section is bent into a U shape in order to prevent deformation. In FIG. 1, elastic thin plate-like metal fingers, electromagnetic shielding gaskets, electromagnetic shielding tapes, and the like are attached to the upper and lower sides of the cross section C of the front plate 3 and the corresponding portion (hatched portion) of the casing 1, and adjacent front plates 3 And electrically connecting the front plate and the housing. This prevents noise from radiating from the gap between the front plates 3 and the gap between the front plate and the housing.

  Also in Patent Document 1, metal fingers are attached to the gaps between adjacent units to shield noise emission. In Patent Document 2, the radiation of noise is shielded by an electromagnetic shield tape.

  Next, the principle of noise resonance and radiation will be described based on paragraph numbers 0008 and 0016 of Patent Document 3 and paragraph numbers 0008 and 0009 of Patent Document 4. When a high frequency generated from an electronic component in the electronic device hits the inside of the housing, a current flows on the surface of the location. Further, if there is a gap in the housing, the high-frequency current flows along the edge of the gap. This current is called a traveling wave. The traveling wave is reflected at both ends of the gap and forms a reflected wave that travels in the opposite direction. When the length of the gap is equal to the half wavelength of the radiation noise, the traveling wave and the reflected wave form a standing wave. In other words, the gap resonates. Next, the principle of radiation is that the current flowing along the edge of the gap forms a magnetic field. The magnetic field forms an orthogonal electric field. The electric field similarly forms orthogonal magnetic fields, and as a result of repeating this, noise is radiated from the gap to the outside of the housing.

  In addition, the value of current flowing in the gap becomes extremely large due to resonance generated in the gap. As a result, the electric field strength of the noise radiated outside the housing is extremely increased. When an electronic device becomes NG in the EMI test, that is, when the electric field strength of the radiated noise is determined to be higher than the reference, the noise radiated after resonance is almost always caused.

JP 2008-31451 A Japanese Patent Laid-Open No. 2004-200444 Japanese Patent Application Laid-Open No. 2002-026637 JP 2006-344933 A

  EMC countermeasure parts such as metal fingers are expensive. In addition, the length of the gap that becomes the noise emission port increases in proportion to the width of the housing, and there are as many gaps as the number of units +1. The amount of EMC countermeasure parts used is considerably increased. Therefore, the EMC countermeasure member cost becomes high.

  Another problem is the time for assembling the EMC countermeasure component to the apparatus. The operation of incorporating the metal fingers into the front plate requires fitting the metal finger feet into the holes one by one, which is very time consuming. The electromagnetic shielding gasket and electromagnetic shielding tape are used by sticking to the front plate. Assembling in a short time is also difficult, such as the occurrence of the work of peeling the release paper of the adhesive, the displacement of the pasting position, and the management of the pasting strength.

  The present invention provides an electronic device that can be realized at low cost and shields noise radiated from a gap between adjacent units. In the electronic device of the present invention, the projections provided on the front plate and the housing of the adjacent units come into contact with each other, thereby preventing noise emission from the gap between the units.

  Since the electronic device of the present invention can remove the EMC countermeasure parts from the apparatus configuration, the member cost and the assembly time can be greatly reduced. And noise emission can be suppressed.

It is a general communication device. It is a figure explaining a housing. It is an expansion perspective view of a housing. It is a figure explaining a package. It is a figure explaining the connection relation of a printed wiring board and a front board. It is a figure explaining the detailed connection relation of a printed wiring board and a front board. It is a figure explaining the package insertion to a housing. It is a front view of the state which inserted the package in the housing. It is a figure explaining the package which attached the thumbscrew to the front plate. It is a figure explaining the package which attached the thumbscrew to the angle.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings using examples. The same reference numerals are assigned to substantially the same parts, and the description will not be repeated.

  With reference to FIG. 2, the housing of Example 1 will be described. Here, FIG. 2A is a perspective view of the housing, and FIG. 2B is a front view of the housing. In FIG. 2A, guides are provided on both inner sides of the metal casing 100. The PKG (package) 200 is inserted into this guide. In FIG. 2B, the housing 100 inserts eight PKGs 200. Slot No. No. 8 makes it easy to understand the number of PKG insertion holes from the bottom. The housing 100 is provided with protrusions 6 on the inner sides of the upper and lower surfaces. In addition, the housing 100 is provided with a spring 7 at a guide portion inside one side of the opening. In an electronic device that holds a substrate horizontally on a vertical surface, both sides are upper and lower surfaces.

  2 and 3, the protrusions 6 are provided on the lower side of the slot No. 1 and the upper side of the No. 8. The protrusion 6 is formed by drawing (embossing). The spring 7 has a shape having elasticity, and the slots No. 1, 3, 5, and 7 are attached only to the left side when viewed from the front of the housing. Conversely, in slots No. 2, 4, 6, 8, the spring 7 is attached only to the right side when viewed from the front of the housing. There is no problem even if the position of the spring 7 is reversed from the above. The functions of the protrusions 6 and the springs 7 provided at equal pitches on the housing will be described later. Further, the guide rail 9 corrects the insertion direction when inserting the PKG 200.

  The structure and configuration of the PKG will be described with reference to FIGS. Here, FIG. 4A is a perspective view of the PKG. FIG. 4B is a rear perspective view of the PKG. FIG. 4C is a partial front view of the front plate of the PKG. As shown in FIGS. 4A and 4B, the protrusions 6 are provided on both the upper side and the lower side of the front plate 10. The protrusions 6 are provided with the same shape and the same pitch as the protrusions provided on the housing 100 described with reference to FIGS. In FIG. 4C, the protrusions 6 are alternately positioned on the upper side and the lower side of the front plate 10, and there is a protrusion 6 on the opposite side at an intermediate position between the two protrusions 6 on the same side.

  The configuration of the PKG will be described with reference to FIG. In FIG. 5, the PKG 200 first fixes an angle (L-shaped bracket) 15 to a PCB (printed wiring board) 5 with screws 12a. A metal front plate 10 is attached to the angle 15 with screws 12b. A bush 11 is fitted into a screw 12b for attaching the front plate 10. The thickness of the bush 11 is designed to be thicker than the thickness of the front plate of the long circular hole 16 portion into which the bush 11 is fitted. The handle 13 is used when inserting and removing PKG. The spring receivers 14 are attached to the left and right sides of the front plate 10. The functions of the spring receiver 14 and the protrusion 6 will be described later.

  The structure of the bush portion will be described with reference to FIG. Here, Fig.6 (a) is a perspective view of a bush peripheral part. FIG. 6B is a front view of the bush periphery. FIG. 6C is a cross-sectional view taken along the line I-I ′ of FIG.

  6A, the height direction of the PKG 200 is defined as the z-axis, the depth direction of the PKG 200 is defined as the y-axis, and the x-axis is defined as the right-handed system. 6C, the front plate 10 has a degree of freedom in the x-axis direction with respect to the PCB 5 even after screwing by making the bush 11 thicker than the thickness of the front plate 10 (with a floating structure). Call). That is, the front plate 10 can be moved in the direction (width direction) indicated by the arrow A in FIG. However, if the thickness of the bush 11 is significantly larger than the thickness of the front plate 10, the front plate 10 has a degree of freedom in the y-axis direction with respect to the PCB 5, and the play of the front plate becomes large. . Therefore, the thickness of the bush 11 needs to be in a range where the front plate 10 is not fixed and the backlash does not increase. As for the size of the oval hole 16 into which the bush 11 provided on the front plate 10 fits, the vertical dimension is preferably the same as or slightly larger than the bush diameter as shown in FIG. This is to prevent the front plate 10 from being given a degree of freedom in the z-axis direction with respect to the PCB 5. In FIGS. 5 and 6, the oval hole having a floating structure is drawn in an oval shape, but in other drawings, it may be drawn simply in a circle. In an electronic device that holds a substrate horizontally on a vertical surface, the width direction is the vertical direction.

  With reference to FIG. 7, the relationship between the spring and the spring receiver when the PKG is inserted into the housing will be described. In FIG. 7, the PKG 200 is inserted into the housing 100 in the order of FIG. 7 (a) → FIG. 7 (b) → FIG. 7 (c). 7A and 7B, the PKG 200 is inserted in the direction of arrow B. In FIG. 7C, the spring 7 finally pushes the spring receiver 14, and the force in the x-axis direction indicated by the arrow C acts on the front plate 10. Here, since the front plate 10 has a floating structure in the ± x-axis direction with respect to the PCB 5, only the front plate 10 moves in the + x-axis direction. As described above, since the springs 7 are alternately provided in the slot No. order, the front plate 10 of the PKG inserted in the slot Nos. 1, 3, 5, and 7 moves to the right when viewed from the front of the housing. The PKG inserted in No. 2, 4, 6, 8 moves to the opposite left.

  With reference to FIG. 8, the function of the protrusion 6 provided on the housing and the front plate will be described. FIG. 8A is a front view and a partially enlarged view when PKG is inserted into a temporary housing without a spring. On the other hand, FIG. 8B is a front view and a partially enlarged view when the PKG is inserted into the housing with the spring 7.

  In FIG. 8A, the plurality of front plates 10 close the plurality of openings of the housing 100. However, adjacent protrusions 6 are not in contact with each other. On the other hand, in FIG. 8B, since the front plate 10 of the PKG 200 moves in the direction of the white arrow, the adjacent protrusions 6 are in contact with each other, and the housing 100 and the front plate 10 are electrically connected to each other. Is done. Note that the length of the gap between the protrusions 6 of the front plate 10 is 1 mm at most and does not cause resonance. Further, all of the eight PKG front plates 10 to be inserted may have the same shape, and it is not necessary to change the shape, pitch, and the like of the protrusions 6 provided on the front plate 10 for each PKG. Therefore, the manufacturing cost of adding the protrusion 6 to the front plate 10 can be suppressed.

  According to the present embodiment, by electrically connecting the protrusions 6 to each other, the gap between the front plates 10 is finely divided, and the length of the gap is half of the noise having the highest frequency among the noises radiated from the electronic device. A standing wave is not formed by making it shorter than the wavelength. That is, since the gap does not resonate, it is possible to prevent the noise of the electric field strength that is determined to be above the reference in the EMI test from being radiated to the outside of the housing.

  However, as a premise, it is necessary that the height of the protrusions 6 be at least half the gap between the front plates. This is because the gap between the front plates cannot be separated if the projections 6 cannot contact each other even if the adjacent front plates are pressed from opposite directions by receiving a force from the spring 7. In this embodiment, there is no restriction on the insertion order of PKG. The width in the x-axis direction of the protrusion 6 of the housing 100 is slightly wider than the width of the protrusion in the front plate 10 in the x-axis direction. This is because the protrusion 6 of the housing 100 does not move. Another solution is to apply a force in the opposite direction with the protrusion-forming surface of the housing 100 as a floating structure.

In the first embodiment, the handle 13 is provided on the front plate 10 of the PKG 200. In Example 2, a thumbscrew that can fix the front plate 10 to the housing is attached instead of the handle.
FIG. 9A is a rear perspective view of the PKG. FIG. 9B is a perspective view for explaining the relationship between the PKG and the housing. In FIG. 9A, the shape of the front plate 10 is slightly different from that of the first embodiment, but the basic feature is the same as that of the first embodiment, and the structure in which the spring 7 pushes the spring receiver 14 is not changed. In FIG. 0B, the front plate 10 can be fixed to the housing by tightening the thumbscrew 18 into the screw hole 19 for the thumbscrew. As in the first embodiment, the order of inserting the PKG is not important. Further, since the front plate 10 has a floating structure, the thumb screw 18 needs to be a floating screw so that the thumb screw 18 can be aligned with the position of the screw hole 19 for the thumb screw.

  In the second embodiment, it is stated that the thumbscrew 18 needs to be a floating screw. Only the front plate 10 moves in the + -x-axis direction, and the PCB 5 is corrected to the guide rail 9 and does not move except in the PKG insertion direction. In the third embodiment, the thumb screw 18A is attached to the angle 20 fixed to the PCB 5. Then, the thumbscrew does not have to be a floating screw.

  FIG. 10A is a rear perspective view of the PKG. FIG. 9B is a perspective view of the PKG. In FIG. 10A, the thumbscrew 18A is attached to the angle 20 fixed to the PCB 5, and is not floating. On the other hand, the screw 12b is attached to the angle 20 in a floating structure. In FIG. 10B, the thumb screw 18A is different in position in the y-axis direction from the thumb screw 18 of FIG. 9, so that the amount of insertion of the PCB 5 into the backboard (not shown) becomes shallow. As a countermeasure, it is preferable to add the bending process of the angle 20 to the same as that in FIG. In Example 3, the shape of the front plate 10 and the angle 20 is slightly different, but the point that the front plate 10 has a floating structure and the position of the spring receiver 14 is pushed and the front plate 10 moves is different. Absent.

  A modified example of the above Example 1-3 will be described below. Although the springs 7 provided on the housing are alternately provided on the left and right in the slot number order, the effect of the embodiment can be obtained even on only one side. Specifically, the springs 7 are provided in the slots No. 1, 3, 5, and 7, and the springs are not provided in the slots No. 2, 4, 6, and 8. Even in such a form, since adjacent protrusions come into contact with each other, it is possible to prevent noise from radiating from the gap between the front plates.

  The protrusion 6 is simply a column with an oval bottom (rounded rectangle) and has a shape with a gradient on the side surface of the column, but may have other shapes. In addition, the electrical connection is more stable when the protrusions 6 are in contact with each other than with the wires. However, if the contact surface is inclined with respect to the insertion direction, the insertion and removal performance of the PKG is deteriorated, or the order of insertion and removal of the PKG is restricted. Therefore, the contact surface is preferably parallel to the insertion direction. Moreover, when the gradient is given to the height direction of the protrusion 6 as in the first embodiment, when the adjacent front plates are pressed from the opposite direction by receiving a force from the spring 7, the front plates are vertically moved by reaction. Move to. As a result, the front plate of slot No. 1 is pushed downward, and the front plate inserted in No. 8 is pushed upward, so that the electrical connection with the projection 6 of the housing becomes more stable.

  The spring 7 may be a separate component spring, or may be a rubber or resin material component as long as it has elasticity. Although the device in which the PKG is inserted in the horizontal direction (parallel to the xy plane) is shown, the device inserted in the vertical direction (parallel to the yz plane) functions similarly. Although the manufacturing method of the projection 6 provided on the front plate 10 and the casing is described as drawing (embossing), other manufacturing methods such as die casting and extrusion + cutting may be used.

  DESCRIPTION OF SYMBOLS 1 ... Housing, 2 ... PKG (package: Printed circuit board unit), 3 ... Front board, 5 ... PCB (Printed Circuit Board), 6 ... Protrusion, 7 ... Spring, 8 ... Slot No., 9 ... Guide rail, 10 ... Front plate, 11 ... bush, 12 ... screw, 13 ... handle, 14 ... spring receiver, 15 ... angle (L-shaped bracket), 16 ... oblong hole, 18 ... thumb screw, 19 ... screw hole for thumb screw, 20 ... Angle, 100 ... Case, 200 ... PKG.

Claims (6)

An electronic device that closes the plurality of openings by inserting a plurality of packages in which a front board is attached to a printed wiring board into a housing having a plurality of continuous openings,
Forming a spring acting on the front plate on one side of the opening;
The electronic device according to claim 1, wherein the front plate includes a plurality of protrusions that are movably attached to the printed board in a width direction of the printed board and are in electrical contact with another adjacent front plate. The electronic device according to claim 1,
The electronic device according to claim 1, wherein the spring is provided on the one side in odd-numbered slots and on the other side in even-numbered slots. The electronic device according to claim 1,
The electronic device according to claim 1, wherein the spring is provided on the one side in odd slots and is not provided in even slots. An electronic device according to any one of claims 1 to 3,
The electronic device, wherein the protrusion is formed by drawing. An electronic device according to any one of claims 1 to 3,
The height of the said protrusion part has the height exceeding 1/2 of the width | variety of the clearance gap between a 1st front board and a 2nd front board, The electronic device characterized by the above-mentioned. An electronic device according to any one of claims 1 to 5,
The housing and the front plate are made of metal.

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