JP2007214443A - Enclosure and electronics - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To suppress the amplification of electromagnetic waves generated inside an enclosure due to a cavity resonance phenomenon. <P>SOLUTION: The enclosure 1 includes a paralellepipedic exterior enclosure member 2 having conductive inner side faces; and conductive partitions 5 extending from a partition mounting face 3 of one of the inner side faces, to a point before an inner side face 4 opposite to the partition mounting face 3 through the inside of the exterior enclosure member 2. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a housing for storing electronic components and an electronic device in which the electronic components are stored in the housing, and more particularly to a housing that suppresses unnecessary electromagnetic radiation from the electronic components.

  In general, electromagnetic waves having various frequency components are generated from circuit boards, power supply circuits, and other units. These electronic components are housed in a housing. However, if electromagnetic waves leak outside the housing, other electronic devices such as a television and a radio may be affected. Such a phenomenon is called EMI (Electro Magnetic Interface) and is currently subject to private voluntary regulations. In high-performance electronic components, it is also important to reduce the influence of electromagnetic waves on the electronic components themselves. Therefore, the housing for storing these electronic components is generally formed of a conductive (metal) material, or formed by coating a thin film of a conductive material on the inner surface of the housing made of plastic or the like. Has been.

  A housing for storing an electronic component is usually provided with an opening for internal cooling and heat dissipation, or an opening for connection provided around the unit, such as a cable connector. These openings have shapes such as holes and slits. Due to the nature of such openings, there is a high need for installation, and electronic devices that operate at high speed, such as high-performance personal computers and routers, tend to increase the opening area. Also, an opening for adding various units later is often provided. These openings also have shapes such as holes and slits. The opening is also generated due to imperfect engagement between the panels constituting the casing. Electromagnetic waves generated inside are also radiated from these openings. Therefore, many techniques for suppressing electromagnetic radiation from the opening of the housing are disclosed as measures against EMI.

  Patent Document 1 discloses a technique in which a material that absorbs electromagnetic waves is provided on an inner surface of a casing around an opening. Patent Document 2 discloses a technique of providing a sheet that absorbs electromagnetic waves over the entire inner surface of a housing. Patent Document 3 discloses a technique of providing a strip-like conductive structure perpendicular to the opening surface along the edges of a plurality of openings provided in the housing. Positive and negative charges are likely to accumulate in the opening of the housing, which becomes a new electromagnetic wave generation source (slot antenna). However, according to such a configuration, current flows through the conductive structure, and charges are not accumulated in the opening, so that radiation of electromagnetic waves due to the antenna effect is suppressed.

  In addition, in order to suppress leakage of unnecessary electromagnetic waves from the slit-like opening due to imperfect engagement between the panels constituting the casing, a metal gasket is often installed in the gap between them. As a result, the electrical connection between the panels constituting the housing is maintained, and leakage of electromagnetic waves is suppressed.

  On the other hand, in order to suppress the emission of electromagnetic waves, it is also effective to suppress the generation of electromagnetic waves themselves. A problem in this regard is the cavity resonance phenomenon. That is, when there is an electromagnetic wave generation source inside the casing, a cavity resonance phenomenon occurs in a rectangular parallelepiped casing whose inner surface is formed of a metallic material, and an electromagnetic wave having a resonance frequency component is amplified inside the casing. The frequency at which the cavity resonance phenomenon occurs (cavity resonance frequency) is determined by the size of the casing. Since the casing is often in the shape of a rectangular parallelepiped, the cavity resonance phenomenon becomes a problem in many casings.

  The cavity resonance phenomenon occurs according to the size of the space inside the housing, and occurs even when the opening is provided. In the case of having an opening, the electromagnetic wave having the resonance frequency amplified inside the housing is radiated from the opening. If the casing is completely sealed, a sufficient shielding effect can be obtained with respect to the outside, and electromagnetic waves are not radiated to the outside. However, in practice, it is difficult to completely eliminate the opening as described above. Therefore, no matter what case is used, electromagnetic waves may be radiated to the outside due to the cavity resonance phenomenon. Further, when electromagnetic waves are amplified inside the housing by the cavity resonance phenomenon, electromagnetic waves interfere with internal substrates and units.

As a technique for suppressing such a cavity resonance phenomenon, Patent Document 4 discloses a technique in which a partition plate made of a conductive material is provided inside a casing. The space inside the housing is completely divided by the partition plate. As described above, since the frequency at which the cavity resonance phenomenon occurs depends on the size of the housing, this adjusts the resonance frequency of the cavity resonance and suppresses the cavity resonance phenomenon of the electromagnetic wave generated from the electromagnetic wave generation source inside the housing. be able to.
Japanese Patent Laid-Open No. 9-8490 Japanese Patent Laid-Open No. 11-177273 JP-A-8-316679 JP-A-5-129790

  As described above, in the housing that houses the electronic components, it is effective to suppress the amplification of the electromagnetic waves inside the housing in order to suppress the radiation of the electromagnetic waves generated inside to the outside. In order to suppress the amplification of electromagnetic waves, it is desirable to shift the cavity resonance frequency of the casing itself from the frequency of electromagnetic waves generated from electronic components inside the casing.

  The techniques described in Patent Documents 1 and 2 cannot be expected to change the cavity resonance frequency of the casing. In the frequency region where the cavity resonance occurs, since the current flowing in the vicinity of the wall surface of the housing is small, the effect is small even if the electromagnetic wave absorbing material is provided on the wall surface. It is also difficult to install the electromagnetic wave absorbing material with a thickness sufficient to effectively absorb the electromagnetic wave having the cavity resonance frequency. From the above, the effect of suppressing the cavity resonance phenomenon is small.

  The technique described in Patent Document 3 suppresses the antenna effect caused by the current flowing through the opening, and cannot suppress the cavity resonance phenomenon that occurs inside the housing. Since the cavity resonance frequency is not related to the size of the opening, the cavity resonance frequency cannot be controlled. In addition, it is necessary to change the conductive structure provided in the opening for each size of the opening.

  Since the technique described in Patent Document 4 completely partitions the inside of the housing, there is a great restriction on the mounting of the printed wiring board and the like, and the cooling performance inside the housing may be affected.

  The method of arranging a gasket or the like between the panels and suppressing leakage of electromagnetic waves from the gap cannot be applied in principle to the opening provided for heat dissipation or the like.

  An object of the present invention is to provide a housing for storing electronic components, which can suppress amplification of electromagnetic waves due to a phenomenon of cavity resonance of electromagnetic waves generated inside the housing. Moreover, an object of this invention is to provide the electronic device provided with this housing | casing.

  The housing of the present invention includes a rectangular parallelepiped outer enclosure member having a conductive inner face, and an inner face that faces the partition plate attachment face from the partition plate attachment face that is one of the inner faces. And a conductive partition plate extending to the front.

  For this reason, the internal space structure of the surrounding member changes, and the cavity resonance phenomenon that depends on the inner space size of the surrounding member is partially disturbed. That is, the cavity resonance phenomenon occurs depending on the size of each region partitioned by the partition plate, and the cavity resonance frequency is shifted to a higher region than when no partition plate is installed. Since the cavity resonance frequency can be freely adjusted by appropriately setting the number of partition plates, the installation interval, etc., the cavity resonance frequency depends on the cavity resonance phenomenon of the electromagnetic wave emitted from the electromagnetic wave generation source provided inside the surrounding member. Amplification can be suppressed.

  The height of the partition plate from the partition plate mounting surface is preferably 1/8 or more of the interval between the partition plate mounting surface and the inner surface facing the partition plate mounting surface.

  It is desirable that the partition plate mounting surface be a surface determined by a first side that is the longest side of the surrounding member and a second side that is the second longest side.

  The partition plate includes a first partition plate extending in parallel with the first side inside the outer member and a first partition plate extending in parallel with the first side and parallel to the second side through the first partition plate. And a second partition plate extending.

  At that time, the length of the side parallel to the first side of each region of the partition plate mounting surface divided by the first and second partition plates is Ai (mm) (i is a natural number of 2 or more), the first For any combination of Ai and Bj where the length of the side parallel to the side of 2 is Bj (mm) (j is a natural number of 2 or more), and M and N are arbitrary natural numbers that are not 0 simultaneously. ,

The value F calculated in (1) may be 1000 or more.

  A rectangular opening may be provided in one region of the partition plate mounting surface, and in this case, the length of each side of the region in which the rectangular opening is provided is 1 to 3 of the length of the long side of the opening. It is desirable to be within the double range.

  The partition plate can be made of a metal material.

  The partition plate may include a communication opening that communicates the front surface and the back surface of the partition plate.

  In this case, the communication opening can be a plurality of holes formed in the partition plate. The communication opening may be formed by a conductive wire knitted into a mesh shape.

  The partition plate may be covered with a radio wave absorber.

  An electronic device of the present invention includes the above-described casing and an electronic component housed in the casing.

  As described above, according to the present invention, it is possible to provide a housing that can suppress amplification of electromagnetic waves generated inside the housing due to a cavity resonance phenomenon. In addition, the present invention can provide an electronic device including such a housing.

  (First Embodiment) An embodiment of the present invention will be described in detail with reference to the drawings.

  Referring to FIG. 1, the housing 1 includes a rectangular parallelepiped surrounding member 2 and a partition plate 5 provided therein. The surrounding member 2 is formed of a conductive metal, but may be a structure having a conductive inner surface such as a conductive thin film formed on the inner surface of a plastic substrate. The surrounding member 2 has a first side 6A having a side length A (mm), a second side 6B having a side length B (mm), and a third side 6C having a side length C (mm). . The side lengths A, B, and C satisfy the relationship of A ≧ B ≧ C. The housing 1 does not have to be a strict rectangular parallelepiped. Even if the corners are rounded, the structure may be approximate to a rectangular parallelepiped as a whole. An electronic component (not shown) such as a printed wiring board (hereinafter referred to as PCB) and various component units is accommodated in the outer member 2.

The cavity resonance frequency Fres (MHz) of the surrounding member 2 can be obtained by Expression 2. Here, L ₀ = 150, (M, N, L) is a set of arbitrary natural numbers that do not simultaneously become zero. When the cavity resonance phenomenon occurs, an electromagnetic wave containing a lot of components of the cavity resonance frequency is radiated to the outside from an opening such as a hole or a slit provided in the surrounding member 2.

  The surrounding member 2 includes an inner side surface formed by the first side 6A and the second side 6B, an inner side surface formed by the second side 6B and the third side 6C, and a third side. There are a total of three types of inner surfaces, the inner surface formed by 6C and the first side 6A. In the present specification, one of the inner side surfaces formed by the first side 6A and the second side 6B is referred to as a partition plate mounting surface 3 among them. Inside the surrounding member 2, there is a gap between the partition plate mounting surface 3 and the front surface 4 facing the partition plate mounting surface 3. A partition plate 5 extending vertically from 3 is formed. Therefore, the internal space of the surrounding member 2 is not completely divided into a plurality of spaces by the partition plate 5 but is maintained as an integral space. The partition plate 5 is made of a conductive material such as a metal material, and is electrically connected to the surrounding member 2 made of the conductive material. The height h of the partition plate 5 from the partition plate mounting surface 3, that is, the length in the direction parallel to the third side 6C, is 1 of the interval (side length C) between the partition plate mounting surface 3 and the opposing surface 4. It is desirable to be / 8 or more. The reason will be described later. The partition plate 5 does not need to extend strictly vertically from the partition plate mounting surface 3, and may be slightly inclined with respect to the partition plate mounting surface 3.

  The partition plate 5 crosses the inside of the surrounding member 2 with the first partition plate 5A extending in parallel with the first side 6A of the partition plate mounting surface 3 and the first partition plate 5A. The second partition plate 5 </ b> B extends in parallel with the second side 6 </ b> B of the surface 3. A plurality of first partition plates 5A and second partition plates 5B are provided, but only one sheet may be provided. Only one of the first partition plate 5A and the second partition plate 5B may be provided. In the present embodiment, the first partition plate 5A is provided at unequal intervals A1, A2, A3, but may be provided at equal intervals. Similarly, the second partition plate 5B is also provided at unequal intervals B1, B2, B3, but may be provided at equal intervals.

  The partition plate mounting surface 3 is divided into regions 71 to 79 by the first partition plate 5A and the second partition plate 5B. Each of the regions 71 to 79 has a planar dimension determined by any one of the intervals A1, A2, and A3 and any one of the intervals B1, B2, and B3. An opening 8 for heat dissipation and ventilation is formed in the central region 75. The opening 8 has a square shape, but may have an arbitrary shape such as a rectangle, a circle, or a slit, and may be composed of a plurality of holes or slits. Note that a housing of a commercially available personal computer or the like often uses an opening provided with a plurality of small holes, and a cooling fan or the like is disposed inside the opening.

  The installation interval between the first partition plate 5A and the second partition plate 5B is generally Ai, Bj (where i and j are natural numbers, at least one is greater than 1), and M and N are simultaneously set to 0. The cavity resonance frequency of each divided region is given by a value F (unit: MHz) calculated by Equation 3 when an arbitrary natural number that does not have to be used.

  By installing the partition plate 5 electrically connected to the surrounding member 2 inside the surrounding member 2, the internal space structure of the surrounding member 2 changes and depends on the inner space size of the surrounding member 2. The cavity resonance phenomenon is partially disturbed. That is, the cavity resonance phenomenon occurs depending on the size of the regions 71 to 79 partitioned by the partition plate 5, and the cavity resonance frequency is shifted to a region higher than the frequency determined by Equation 2. Since the electric field strength of the electromagnetic wave emitted from the electronic component housed in the surrounding member 2 has few flat frequency characteristics, the cavity resonance frequency should not overlap with the frequency region where the electric field strength is high. If the partition plate 5 is disposed, the cavity resonance phenomenon can be suppressed. For this reason, not only the electromagnetic wave emission to the outside is effectively suppressed, but also the electromagnetic interference to the internal electronic components is reduced.

  If the value F is set to 1000 or more, that is, the cavity resonance frequency of all the regions 71 to 79 is set to 1 GHz or more, it is easy to comply with the current private voluntary regulations. In this embodiment, it is also effective for the need to suppress the emission of electromagnetic waves having a certain frequency or less.

  FIG. 2 is a conceptual diagram showing a modification of the present embodiment. A heat dissipation opening 108 is provided in the vicinity of the center of the partition plate mounting surface 103 of the surrounding member 102. The opening 108 can have any shape such as a square, a rectangle, a circle, or a slit. The partition plate 105 is partially provided so as to surround the opening 108, and does not reach the outer peripheral portion of the partition plate mounting surface 103. The partition plate 105 is electrically connected to the surrounding member 102. In the case of a housing having an opening, electromagnetic waves generated inside are likely to be emitted from the opening. Therefore, the amplification of the electromagnetic wave in the vicinity of the opening can be suppressed by simply installing the partition plate around the opening.

(Second Embodiment)
FIG. 3 is a configuration diagram of a housing according to the second embodiment of the present invention. A conductive partition plate 205 is installed inside the enclosure member 202 as in the first embodiment. The difference from the first embodiment is that the partition plate 205 includes a communication opening 209. The communication opening 209 may be provided in the entire region of one partition plate 205 or in a part or the entire region of each partition plate 205. The communication opening 209 is a plurality of holes that are formed in the partition plate 205 and communicate with the front surface and the back surface of the partition plate 205. The shape of the hole is arbitrary such as a circle or a slit. The communication opening 209 is provided so that the maximum size of the hole is 1/10 to 1/20 or less of the wavelength of the electromagnetic wave corresponding to the resonance frequency generated inside the outer member 202. In general, an electromagnetic wave cannot pass through an opening having a size of 1/10 to 1/20 or less of the wavelength, and therefore, such an opening is the same as not existing for the electromagnetic wave. Therefore, even if a partition plate provided with a small communication opening is used, the same effect as that of the first embodiment can be obtained. According to this embodiment, since there is a communication opening in the partition plate, there is a merit that the flow of air inside the housing is further promoted, and the internal cooling and heat dissipation effect is enhanced.

(Third embodiment)
FIG. 4 is a configuration diagram of a housing according to the third embodiment of the present invention. A conductive partition plate 305 is installed inside the enclosure member 302 as in the first embodiment. Also in this embodiment, the partition plate 305 includes a communication opening 309 as in the second embodiment, but the communication opening 309 is formed of a conductive wire knitted in a mesh shape. The communication opening 309 may be provided in the entire region of one partition plate 305 or in a part or the entire region of each partition plate 305. As in the second embodiment, the mesh interval is desirably 1/10 to 1/20 or less of the wavelength of the electromagnetic wave of interest. In this case, the same effect can be obtained for the same reason as in the second embodiment. Moreover, since the partition plate part has a mesh structure, the air flow inside the housing is further promoted than in the second embodiment.

(Fourth embodiment)
FIG. 5 is a configuration diagram of a housing according to the fourth embodiment of the present invention. A conductive partition plate 405 is installed inside the enclosure member 402 as in the first embodiment. Both surfaces of the partition plate 405 are covered with a radio wave absorber 410. The radio wave absorber 410 is formed by applying a substance that absorbs an electromagnetic wave having a frequency of interest or attaching a radio wave absorption sheet. By providing the radio wave absorber 410, the electromagnetic wave contributing to the resonance phenomenon generated inside the surrounding member 402 is suppressed not only by the change in the internal space of the surrounding member 402 but also by the effect of the surface material of the partition plate 405. Therefore, electromagnetic wave radiation to the outside can be more effectively suppressed. In addition, the electromagnetic wave amplified by the resonance phenomenon appears more strongly in the space portion (center portion) of the surrounding member 402 than in the inner wall surface of the surrounding member 402. In the present embodiment, the radio wave absorber 410 can be easily provided at a position where the electric field strength is relatively large, so that the electromagnetic wave absorption effect is further enhanced.

  In addition, it can be expected that the electromagnetic wave suppression effect and the heat dissipation effect can be improved at the same time by combining the radio wave absorber in the present embodiment and the structure of the partition plate in the second and third embodiments. Moreover, the partition plate combined with an electromagnetic absorber is not restricted to the example of this embodiment.

  Next, examples corresponding to the embodiments described above will be described. Examples 1 to 4 correspond to the first to fourth embodiments, respectively.

Example 1
An aluminum surrounding member having a thickness of 1.5 mm, a side length A of 500 mm, a side length B of 350 mm, and a side length C of 200 mm was produced. Next, two aluminum plates each having a thickness of 1.5 mm and plane dimensions of 500 mm × 50 mm and 350 mm × 50 mm were prepared, for a total of four. Next, four aluminum plates are assembled as a partition plate in a lattice shape so as to be 50 mm in height perpendicular to the partition plate mounting surface of the surrounding member, and using conductive tape or conductive paint And it attached so that it might electrically connect with the partition plate attachment surface of an outer enclosure member. The opening was provided in the center area | region of the partition plate attachment surface divided by the partition plate. Next, a conductive (Cu) plate simulating PCB is attached to the surface facing the partition plate mounting surface to which the partition plate is mounted, using an insulator or the like so as not to be electrically connected to the surrounding member. . Next, a Cu wire of about 10 mm was connected to the PCB via the SMA connector, and a signal from 30 MHz to 1 GHz was input to measure the radiated electric field intensity at 3 m in the anechoic chamber. As a comparative example, a case without a partition plate was also prepared.

  When no partition plate was provided inside the outer member, it was observed that the radiation electric field intensity increased at some of the frequencies calculated by Equation 2. On the other hand, when the partition plate was provided, it was confirmed that the radiated electric field intensity at that frequency was reduced by approximately 20 dB or more, particularly in the fundamental mode (the lowest frequency mode). The same effect was obtained when the surrounding member and the partition plate were made of a steel plate having a thickness of 1 mm.

  Next, a three-dimensional electromagnetic field analysis was performed using the FDTD method for a case model having the same configuration as the case described above. The structural model of the surrounding member used for the analysis was a rectangular parallelepiped having a side length A of 500 mm, a side length B of 350 mm, and a side length C of 200 mm. The resonance frequency calculated by Expression 2 is 300, 428, 523, 737, 857, 899, 907, 996,. Next, in order to calculate the far-field electric field strength, a three-dimensional electromagnetic field simulation by the FDTD method was performed with a structure in which a square opening of 50 mm × 50 mm was provided on one surface of the housing model and internal electromagnetic waves leaked to the outside. It was. A ground plate to which a cable is connected is disposed inside the housing, and a signal source that maintains a constant electromagnetic wave intensity level in a frequency range up to several GHz is disposed between the cable and the PCB. As an electromagnetic wave generation factor, common mode noise flowing in the PCB and a case where the PCB operates as an antenna were assumed.

  First, in the case where no partition plate was provided, the far-field radiation electric field strength at the 3 m position was calculated. FIG. 6 shows a radiation electric field intensity spectrum obtained as a result of the calculation. The radiated electric field strength sharply increased near 445 MHz and 890 MHz, and it was reproduced by simulation that the radiated electric field strength increased at a specific frequency among the resonance frequencies obtained by Equation 2. The reason why the number of resonance frequency peaks is smaller than the calculated value is considered to be due to the influence of the symmetry due to the position of the signal source, the mode of the electromagnetic field radiated from the PCB, and the like. Through this analysis, it was confirmed that the resonance phenomenon at the peak frequency shown in FIG. 6 occurred inside the housing, and the electromagnetic wave of the component was radiated from the opening. In addition, although the case where opening was installed in the surface orthogonal to the partition plate attachment surface shown in FIG. 1 was also examined, the radiation electric field strength spectrum similar to FIG. 6 was obtained.

  Next, in the case where the partition plate was provided, the far radiation electric field strength at the 3 m position was calculated. Specifically, a plurality of partition plates similar to those of the above-described prototype example are arranged perpendicular to the partition plate mounting surface and in parallel with each side of the surrounding member, and are electrically connected to the surrounding member. The partition plate was an aluminum plate and the opening was set in the central region. In FIG. 7, the analysis result performed using the height of the partition plate as a parameter is shown. It was confirmed that the radiated electric field intensity was reduced as compared with the case without the partition plate. In order to obtain a reduction effect of 10 dB or more, the height of the partition plate may be secured by 1/8 or more of the side length C. If the height of the partition plate exceeds 1/2 of the side length C, the effect tends to saturate, and restrictions on mounting of electronic components also increase, so it is not preferable to make it too large. When the height of the partition plate is equal to the side length C of the surrounding member, it is the same as making a fine casing separately, and is different from the technical idea of the present invention.

  Next, a square opening having a side length D (mm) was provided in the central region partitioned by the partition plate, and the far field electric field intensity was calculated at a position of 3 m using the partition plate installation interval as a parameter. FIG. 8 shows the calculation result of the radiation electric field intensity. When the installation interval is 4D, the reduction of the primary peak component of the cavity resonance is 10 dB or less compared to the case where there is no partition plate. The reduction effect increases as the installation interval decreases. Assuming that the opening is accommodated in one area, if the length of each side of the area provided with the square opening is within a range of 1 to 3 times the side length of the opening, the reduction is 10 dB or more. An effect is obtained. The opening may be generally rectangular, and in the case of a rectangle, the long side may be D. However, when it is desired to suppress the emission of electromagnetic waves below a predetermined frequency (for example, 1 GHz), it is necessary to make the cavity resonance frequency calculated by Equation 3 equal to or lower than the predetermined frequency.

  In the above calculation, the opening is disposed in the central region of the partition plate mounting surface of the surrounding member. However, the same calculation result can be obtained even if the opening is provided in a region near the periphery of the partition plate mounting surface.

(Example 2)
The same material and the same size housing as in Example 1 and a partition plate made of an aluminum plate of the same size as in Example 1 were manufactured. In the partition plate, holes having a diameter of about 3 mm were formed at a pitch of 10 mm. Other structures were the same as in Example 1. Next, the partition plate was attached to the inside of the surrounding member while being electrically connected to the surrounding member in the same manner as in Example 1. Using the casing thus produced, the far field intensity at 3 m was measured. As a result, it was confirmed that the same radiation reduction effect as in Example 1 was obtained.

(Example 3)
The same material and the same size housing as in Example 1 and a partition plate made of an aluminum plate of the same size as in Example 1 were manufactured. The partition plate was provided with a mesh portion knitted with a 0.5 mm diameter Cu wire at an interval of about 2 mm. Other structures were the same as in Example 1. Next, the partition plate was attached to the inside of the surrounding member in the same manner as in Example 1. Using the casing thus produced, the far field intensity at 3 m was measured. As a result, it was confirmed that the same radiation reduction effect as in Example 1 was obtained.

Example 4
Next, a casing made of the same material and the same size as in Example 1 and an aluminum plate having the same size as in Example 1 were manufactured. A ferrite sheet having a thickness of 1 mm to 2 mm was attached to the entire area of both sides of the partition plate. Other structures were the same as in Example 1. Next, the partition plate was attached to the inside of the surrounding member in the same manner as in Example 1. Using the casing thus produced, the far field intensity at 3 m was measured. As a result, it was confirmed that the radiation field intensity reduction effect of 2 to 5 dB was further obtained than in the case of Example 1.

It is a schematic perspective view which shows the inside of the housing | casing by the 1st Embodiment of this invention. It is a schematic perspective view which shows the modification of the housing | casing by 1st Embodiment. It is a schematic perspective view which shows the inside of the housing | casing by the 2nd Embodiment of this invention. It is a schematic perspective view which shows the inside of the housing | casing by the 3rd Embodiment of this invention. It is a schematic perspective view which shows the inside of the housing | casing by the 4th Embodiment of this invention. It is a radiation electric field strength spectrum of a housing | casing when the partition plate is not installed. It is a graph of the radiation electric field strength of a housing | casing which made the height of the partition plate the parameter. It is a graph of the radiation electric field strength of a housing | casing which made the installation space | interval of a partition plate a parameter.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Housing | casing 2,102,202,302,402 Outer member 3,103,203,303,403 Partition plate attachment surface 4 Opposite surface 5,105,205,305,405 Partition plate 5A 1st partition plate 5B 1st 2 partition plates A, B, C Side length 6A First side 6B Second side 6C Third side 8, 108, 208, 308, 408 Opening 71-79 Area 209, 309 Communication opening 410 Wave absorber

Claims (12)

A rectangular parallelepiped enclosure member having a conductive inner surface;
A conductive partition plate extending from the partition plate mounting surface which is one of the inner side surfaces to the front of the inner side surface facing the partition plate mounting surface, inside the outer member;
A housing having   The height of the said partition plate from the said partition plate attachment surface is 1/8 or more of the space | interval of the said partition plate attachment surface and the inner surface facing this partition plate attachment surface. body.   The housing according to claim 1 or 2, wherein the partition plate mounting surface is a surface determined by a first side that is the longest side of the surrounding member and a second side that is the second longest side. body. The partition plate is
A first partition plate extending in parallel with the first side inside the surrounding member;
A second partition plate extending in parallel with the second side, intersecting the first partition plate, and the inside of the surrounding member;
The housing according to claim 3, comprising: Ai (mm) (i is a natural number of 2 or more), the length of the side parallel to the first side of each region of the partition plate mounting surface divided by the first and second partition plates, When the length of the side parallel to the second side is Bj (mm) (j is a natural number of 2 or more), and M and N are arbitrary natural numbers that are not 0 simultaneously, for any combination of Ai and Bj And

The housing | casing of Claim 4 from which the value F calculated by is 1000 or more. A rectangular opening is provided in one area of the partition plate mounting surface,
The case according to claim 5, wherein the length of each side of the region in which the rectangular opening is provided is in a range of 1 to 3 times the length of the long side of the opening.   The housing according to any one of claims 1 to 6, wherein the partition plate is made of a metal material.   The casing according to any one of claims 1 to 7, wherein the partition plate includes a communication opening that communicates a front surface and a back surface of the partition plate.   The housing according to claim 8, wherein the communication opening is a plurality of holes formed in the partition plate.   The casing according to claim 8, wherein the communication opening is formed by a conductive wire knitted in a mesh shape.   The housing according to claim 1, wherein the partition plate is covered with a radio wave absorber. A housing according to any one of claims 1 to 10,
Electronic components housed in the housing;
Electronic equipment having

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