JP2010038559A - Apparatus, method and program for evaluating performance of electromagnetic wave shielding structure - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method and apparatus for efficiently evaluating a shielding performance of a shielding structure of an electronic device. <P>SOLUTION: A CPU 120 calculates a contribution of an opening in the shielding structure on an electromagnetic field in an observation region far from the shielding structure based on an electromagnetic field analysis program 201 and a contribution calculation program 202 stored in a hard disk 122. The CPU 120 configures a projection of the opening to a reference plane surrounding the shielding structure as a leakage candidate region. The CPU 120 calculates the contribution as a ratio of an electromagnetic field value of the observation region having a wave source as the electromagnetic field in the leakage candidate region to an electromagnetic field value of the observation region having a wave source as the electromagnetic field on the entire reference plane. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a technique for evaluating the performance of a structure for shielding electromagnetic waves. In particular, the present invention relates to a technique for determining the degree of contribution to a far electromagnetic field at a location where electromagnetic waves leak in a structure.

  2. Description of the Related Art In recent years, EMI (Electro Magnetic Interference) problems caused by unnecessary electromagnetic waves radiated from electronic devices have become apparent in electronic devices as circuit density and signal speed increase. For example, unnecessary electromagnetic waves cause problems such as degradation of power supply quality and signal quality and occurrence of malfunction of equipment.

  For this reason, standards such as VCCI (Voluntary Council for Radio Wave Interferences such as Information Processing Devices) are provided for the level of unnecessary electromagnetic waves radiated from electronic devices. In designing electronic devices, various measures are taken to satisfy these standards. If the standard is not satisfied, further measures need to be taken. At this time, it is very important to specify a location that causes unnecessary electromagnetic waves.

So far, techniques for identifying the cause of unnecessary electromagnetic waves have been proposed. For example, as described in Patent Document 1, a method for calculating the influence of individual currents on the surface of an object serving as a wave source of electromagnetic waves on a far electromagnetic field has been proposed. In the technique described in Patent Document 1, the ratio of the far electromagnetic field created by each current to the far electromagnetic field created by the entire object is obtained as an index of the influence of each current on the far electromagnetic field.
JP 2002-277500 A

  In the standards such as VCCI, the electromagnetic wave at a point sufficiently separated from the electronic device as an evaluation target with respect to the size of the electronic device (for example, a point 3 [m] or 10 [m] away from the target). The world is often evaluated.

  Therefore, when evaluating an electronic device, in order to identify the location of the electronic device that affects the far electromagnetic field, not the influence (contribution) to the vicinity of the electromagnetic field created by the electronic device but the contribution to the far field. It is necessary to judge. According to the method proposed in Patent Document 1, it is possible to determine the degree of contribution of individual currents (described as current elements in Patent Document 1) flowing through each point on the evaluation object to a distant place.

  By the way, an electronic device may be covered with an electromagnetic wave shielding structure (hereinafter referred to as a shielding structure) such as a metal shield case. Evaluation of an electronic device covered with a shielding structure using the method described in Patent Document 1 is inefficient as described below.

  Of the electromagnetic waves generated by the electronic device covered with the shielding structure, it is expected that the electromagnetic waves passing through the openings (slits, etc.) of the shielding structure will affect the far electromagnetic field. However, since the method described in Patent Document 1 does not consider the structure of the shielding structure, it is not possible to efficiently identify a location that affects the far electromagnetic field.

  Moreover, the opening part which is not intended by design may arise in a shielding structure. For example, in design, there may be a gap in connection between the shield case and the chassis in contact with each other by screwing or the like. According to the method described in Patent Document 1, it is not possible to determine the degree of contribution to the far electromagnetic field at such a location.

  As described above, in the method described in Patent Document 1, the electronic component surrounded by the shielding structure actually affects the electromagnetic field at a distant point that is an evaluation target in the standard. The location cannot be identified efficiently. Therefore, a wasteful period and an increase in man-hours are caused for EMI countermeasures.

  The present invention has been made to solve the above problems, and an object of the present invention is to provide a method and an apparatus for efficiently evaluating the shielding performance of a shielding structure of an electronic device.

  The present invention according to one aspect is an electromagnetic wave shielding structure performance evaluation apparatus for evaluating the performance of an electromagnetic wave shielding structure surrounding an electromagnetic wave generation source, and an analysis model of a space including the electromagnetic wave generation source and the electromagnetic wave shielding structure And a leakage candidate area corresponding to the opening of the electromagnetic shielding structure on a reference plane surrounding the electromagnetic shielding structure, and an electromagnetic field for acquiring electromagnetic field information of the leakage candidate area Based on the electromagnetic field information of the acquisition unit, the analysis model, and the leakage candidate region, the electromagnetic field in the observation region farther from the electromagnetic shielding structure than the reference plane, using the electromagnetic field of the leakage candidate region as a wave source A contribution calculating unit for calculating an opening contributing electromagnetic field.

  Preferably, the electromagnetic field acquisition unit sets a projection region on the reference plane of the region of the opening as the leakage candidate region.

  Preferably, the electromagnetic field acquiring unit further acquires electromagnetic field information on the reference surface, and the contribution calculating unit is based on the analysis model and electromagnetic field information on the reference surface. A reference plane contribution electromagnetic field that is an electromagnetic field in the observation region is calculated using an electromagnetic field as a wave source, and the electromagnetic field in the observation region is a ratio of the value of the aperture contribution electromagnetic field to the value of the reference plane contribution electromagnetic field. The contribution of the opening to the field is calculated.

  More preferably, the contribution calculation unit extracts a specific point where the value of the reference plane contribution electromagnetic field is equal to or greater than a predetermined value in the observation region, and calculates the contribution at the specific point.

  Preferably, the electromagnetic field acquisition unit sets the opening in a connection portion of the parts of the electromagnetic shielding structure.

  The present invention according to another aspect is a performance evaluation method for an electromagnetic wave shielding structure surrounding an electromagnetic wave generation source using an arithmetic device including an arithmetic unit and a storage unit, wherein the arithmetic unit is configured to transmit the electromagnetic wave from the storage unit. A step of reading an analysis model of a space including the generation source and the electromagnetic wave shielding structure, and a leak candidate region corresponding to the opening of the electromagnetic wave shielding structure on the reference plane surrounding the electromagnetic wave shielding structure by the arithmetic unit A step in which the calculation unit acquires electromagnetic field information of the leakage candidate region, and the calculation unit calculates the leakage candidate region based on the analysis model and the electromagnetic field information of the leakage candidate region. And calculating an aperture-contributing electromagnetic field that is an electromagnetic field in an observation region farther from the electromagnetic shielding structure than the reference plane.

  The invention of the present application according to still another aspect is a performance evaluation program for an electromagnetic shielding structure for causing a computing device including a computing unit and a storage unit to perform performance evaluation of an electromagnetic shielding structure surrounding an electromagnetic wave generation source, A step of reading an analysis model of a space including the electromagnetic wave generation source and the electromagnetic wave shielding structure from a storage unit; and a leakage candidate region corresponding to an opening of the electromagnetic wave shielding structure on a reference plane surrounding the electromagnetic wave shielding structure A step of acquiring electromagnetic field information of the leakage candidate area, and using the electromagnetic field of the leakage candidate area as a wave source based on the analysis model and the electromagnetic field information of the leakage candidate area Calculating the aperture-contributing electromagnetic field, which is an electromagnetic field in the observation region farther from the electromagnetic wave shielding structure than the plane,

  According to the present invention, the leakage candidate region corresponding to the opening of the shielding structure is set on the reference plane surrounding the shielding structure, and the electromagnetic field of the far-field observation region is set using the electromagnetic field of the leakage candidate region as a wave source. calculate. As a result, the electromagnetic wave shielding performance of the shielding structure can be efficiently evaluated.

  Alternatively, according to the present invention, a remote electromagnetic field can be calculated by setting a location where there is actually a gap but no gap in design as an opening. In this way, although there is no problem in design, it is possible to efficiently identify a region that is actually a leakage point of electromagnetic waves.

  Hereinafter, embodiments of the present invention will be exemplarily described based on the drawings. The configurations, dimensions, shapes, other relative arrangements, and the like described below are not intended to limit the present invention only to those unless otherwise specified.

  As will be apparent from the following description, the simulation program according to the present embodiment specifies an electromagnetic wave leakage location that actually affects a distant point in an electromagnetic wave shielding structure having an opening, and takes time for EMI countermeasures. Can be omitted.

(1. System configuration)
A hardware configuration of a computer 100 that executes a simulation program according to the present embodiment will be described with reference to FIG. FIG. 1 is a block diagram showing the configuration of a computer 100 that executes a simulation program according to the present embodiment.

  A computer 100 shown in FIG. 1 includes a computer main body 101, a flexible disk (hereinafter referred to as "FD") drive 103, an optical disk drive 104, a communication interface 105, a monitor 106 as a display device, and an input device. As a keyboard 107 and a mouse 108. The FD drive 103, the optical disk drive 104, the communication interface 105, the keyboard 107 and the mouse 108 are each connected to the computer main body 101 via the bus 102.

  The FD drive 103 reads and writes information from and to the FD 113. The optical disc drive 104 reads information on an optical disc such as a CD-ROM (Compact Disc Read-Only Memory) 114. The communication interface 105 exchanges data with the outside.

  The computer main body 100 includes a CPU (Central Processing Unit) 120, a memory 121 including a ROM (Read Only Memory) and a RAM (Random Access Memory), and a hard disk 122. The CPU 120, the memory 121, and the hard disk 122 are each connected to the bus 102.

  The hard disk 122 is a design shape of an analysis object such as an electromagnetic shielding structure or an electronic device (for example, a printed circuit board on which a circuit element is mounted) including a wave source through which a current flows, a dielectric constant of a medium constituting the analysis object, and the like Computer-aided design (CAD) data 200 that specifies parameters and the like representing the physical properties of the computer, an electromagnetic field analysis program 201, a contribution calculation program 202 that calculates the contribution to the far electromagnetic field, and an electromagnetic field analysis Analysis condition 203, analysis object analysis model 204, electromagnetic field analysis result 205, and contribution 206 are stored. The hard disk 122 is an example of a direct access memory device, and other types of direct access memory devices may be used instead of the hard disk 122.

  Here, for example, the CAD data 200 and the analysis condition 203 may be supplied from an external database via the communication interface 105. Further, the electromagnetic field analysis program 201 and the contribution calculation program 206 may be supplied by a storage medium such as the FD 113 or the CD-ROM 114, or may be supplied by another computer via a communication line. The electromagnetic field analysis may be executed by an external computer via the communication interface 105 and the result may be stored in the hard disk 122.

  The simulation program (electromagnetic field analysis program 201, contribution calculation program 202) according to the present invention is software executed by the CPU 120 as described above. Generally, such software is stored and distributed in a storage medium such as a CD-ROM or FD, read from the storage medium by the optical disk drive 114 or the FD drive 113, and temporarily stored in the hard disk 122. Alternatively, when the computer 100 is connected to the network, it is temporarily copied from the server on the network to the hard disk 122. Further, it is read from the hard disk 122 to the RAM in the memory 121 and executed by the CPU 120. In the case of network connection, the program may be directly loaded into the RAM and executed without being stored in the hard disk 122.

  The hardware itself of the computer 100 shown in FIG. 1 and its operating principle are general. Therefore, an essential part for realizing the functions of the present invention is software stored in a storage medium such as the FD 113, the CD-ROM 114, and the hard disk 122.

  The functional configuration of the CPU 120 will be described with reference to FIG. FIG. 2 is a block diagram illustrating a functional configuration of the CPU 120. Referring to FIG. 2, CPU 120 includes an electromagnetic field analysis unit 210, a contribution calculation unit 220, and an analysis control unit 230 that controls the electromagnetic field analysis unit 210 and the contribution calculation unit 220.

  The electromagnetic field analysis unit 210 performs electromagnetic field analysis according to the electromagnetic field analysis program 201. The electromagnetic field analysis unit 210 includes a model creation unit 211 and an analysis execution unit 212.

  The model creation unit 211 creates an analysis model to be analyzed. More specifically, the model creation unit 211 obtains design shape information of the electromagnetic wave shielding structure, mechanism design information of a wave source (for example, a circuit board or an antenna) in the electromagnetic wave shielding structure, and electromagnetic field analysis from the CAD data 200. Required physical property values such as dielectric constant, magnetic permeability, and electrical conductivity are extracted. Then, the model creation unit 211 creates an analysis model 204 according to the analysis condition 203 based on the extracted data.

  For example, when performing electromagnetic field analysis by the FDTD (Finite Difference Time Domain) method, the model creation unit 211 divides the analysis space by the cell size given by the analysis condition 203, and each cell satisfies each cell. An analysis model 204 is created with physical property values according to the above.

  The model creation unit 211 stores the created analysis model 204 in the hard disk 122.

  The analysis execution unit 212 executes electromagnetic field analysis such as the FDTD method. More specifically, the analysis execution unit 212 reads the analysis model 204 stored in the hard disk 122 and calculates the electromagnetic field in the analysis space according to the analysis condition 203 (for example, the time step of the FDTD method). In particular, the analysis execution unit 212 calculates an electromagnetic field on a closed curved surface (referred to as a reference surface) set so as to surround the structure. Then, the analysis execution unit 212 writes the analysis result 205 to the hard disk 122.

  The contribution calculation unit 220 calculates the contribution 206 to the far electromagnetic field of the leakage candidate region based on the electromagnetic field analysis result 205 of the electromagnetic field analysis unit 210 in accordance with the contribution calculation program 202 as follows.

  First, the contribution calculation unit 220 acquires the opening of the electromagnetic shielding structure from the CAD data 200. The contribution calculation unit 220 regards the slit of the structure or the joint of the parts of the structure as an opening.

  Next, the contribution degree calculation unit 220 sets an area where the opening is projected on the reference plane as an electromagnetic wave leakage candidate area. When there are a plurality of openings, the contribution calculation unit 220 sets a projection area corresponding to each opening as a leakage candidate area.

  Here, it is assumed that the contribution calculation unit 220 sets an area obtained by projecting the opening obtained from the CAD data 200 on the reference plane as a leakage candidate area. However, the method for setting the leakage candidate area is not limited to this. For example, the contribution degree calculation unit 220 may set an area on the reference plane corresponding to the opening as a leakage candidate area based on an input to the keyboard 107 by the user.

  Then, based on the electromagnetic field analysis result 205, the contribution calculation unit 220 calculates an electromagnetic field in a distant observation region using the electromagnetic fields on the reference plane and the leakage candidate region as wave sources. Specifically, the contribution calculation unit 220 calculates the electromagnetic field in the observation region using each of the electromagnetic fields on the reference plane and the leakage candidate region as a secondary wave source such as an equivalence theorem. Note that the contribution calculation unit 220 may calculate the electromagnetic field in the observation region using a method of converting a detailed mesh to a coarse mesh on an arbitrary boundary surface such as the FDTD-MAS method.

  Thus, in the shielding structure evaluation method according to the present embodiment, a far electromagnetic field is calculated by regarding the leakage candidate region corresponding to the opening as a wave source. Therefore, it is possible to reduce the load of the far electromagnetic field calculation process.

  Then, based on the calculated electromagnetic field magnitude in the far field, the contribution 206 of the leakage candidate area to the far field is calculated and stored in the hard disk 122. Here, the contribution of the leakage candidate area to the far electromagnetic field is the ratio of the electromagnetic field value given from the leakage candidate area to the electromagnetic field value given from the entire analysis surface at a specific point on the far field. Say.

  Preferably, the contribution calculation unit 220 has a point where the electromagnetic field strength value exceeds a predetermined standard value (for example, the VCCI standard value) or the maximum or maximum electromagnetic field strength in the electromagnetic field strength in the far field. A point is a specific point. The condition for determining the specific point is included in the analysis condition 203. And the contribution calculation part 220 calculates | requires the contribution in a specific point. The calculation load is reduced by obtaining the contribution of the specific point after obtaining the specific point.

  In the above description, the contribution calculation unit 220 calculates the contribution based on the electromagnetic field analysis result 205 obtained by an analysis method such as the FDTD method. However, the contribution degree calculation unit 220 may calculate the contribution degree using the measurement result of the electromagnetic field instead of the electromagnetic field analysis result 205. For example, a user observes the amplitude and phase of an electromagnetic field at each point on a closed curved surface surrounding a metal structure using an electromagnetic field measuring device such as a probe, and the observation result is displayed on a hard disk instead of the electromagnetic field analysis result 205. 122 may be stored. In this case, the space that can be measured by the electromagnetic field measuring apparatus corresponds to the analysis space.

(2. Analysis process (1))
Hereinafter, a method for evaluating the shielding performance of the metal structure 301 as shown in FIGS. 3 and 4 will be described. More specifically, a method for analyzing the influence of unnecessary electromagnetic waves leaking from the metal structure 301 on the far electromagnetic field will be described. FIG. 3 is a bird's-eye view of the metal structure 301. FIG. 4 is a cross-sectional view of the metal structure 301 as viewed from the side.

  With reference to FIG. 3 and FIG. 4, the metal structure 301 which is an evaluation object has a slit 302a and a slit 302b. Hereinafter, when the slit 302a and the slit 302b are not distinguished, they are collectively referred to as the slit 302. Inside the metal structure 301, a wave source 401 (for example, an antenna or a printed board) is disposed. In other words, the metal structure 301 is disposed so as to surround the wave source 401. The metal structure 301 is in contact with the chassis 303.

  With reference to FIG. 5, calculation of a value in the far field of the electromagnetic field generated from the entire metallurgy structure 301 and determination of a specific point in the far field, which are necessary for the shielding performance evaluation, will be described. FIG. 5 is a diagram for explaining the analysis plane, the observation region, and the specific point.

  First, the electromagnetic field analysis unit 210 analyzes a closed curved surface (surface sufficiently close to the distance from the metal structure 301 to a region where the influence of unnecessary electromagnetic waves is to be evaluated) as shown in FIG. The electromagnetic field on the analysis surface 501 is obtained by setting the surface 501.

  Next, the contribution degree calculation unit 220 regards the electromagnetic field of the entire analysis surface 501 as a wave source, and is an area (hereinafter referred to as observation) at a predetermined distance (for example, a distance determined by the EMI standard) from the metal structure 301. The electromagnetic field of area 502) is calculated. For example, the electromagnetic field of the observation region 502 is calculated by regarding the electromagnetic field of the entire analysis surface 501 as a secondary wave source of the equivalent theorem. Here, the reason for using the equivalence theorem is that the time and hardware resources required for the analysis can be reduced while the electromagnetic field in the far region is directly obtained by the FDTD method or the like.

  In this calculation method, an electromagnetic field leaking from the slit 302 of the metal structure 301 is replaced with an electromagnetic field on the analysis surface 501. This replacement does not affect the calculation result of the electromagnetic field in the observation region 502. The distance between the metal structure 301 and the analysis surface 501 is sufficiently shorter than the distance between the metal structure 301 and the observation region 502, and the electromagnetic field on the analysis surface 501 is a slit of the metal structure 301. This is because it can be considered that the electromagnetic field leaking from 302 is substantially equal.

  Next, the contribution calculation unit 220 sets, as the specific point 503, a point in the observation region 502 where the electromagnetic wave of the entire analysis surface 501 calculated by the above method satisfies a predetermined condition. Specifically, the contribution calculation unit 220 sets, as the specific point 503, a point where the electromagnetic wave intensity takes a value larger than a predetermined value (for example, the standard value of EMI) or the maximum point of the electromagnetic field intensity. .

  Next, with reference to FIG. 6, the calculation of the value in the far region of the electromagnetic field generated from the leakage candidate region and the calculation of the contribution necessary for the shielding performance evaluation will be described. FIG. 6 is a diagram for explaining setting of a leakage candidate region and calculation of a contribution degree.

  First, as illustrated in FIG. 6, the contribution calculation unit 301 projects the areas of the slits 302 a and 302 b in the metal structure 301 onto the analysis surface 501. The contribution calculating unit 301 sets the projection areas of the slits 302a and 302b as electromagnetic wave leakage candidate areas 601a and 601b, respectively. Hereinafter, when the leakage candidate area 601a and the leakage candidate area 601b are not distinguished, they are collectively referred to as the leakage candidate area 601.

  Next, the contribution calculation unit 301 calculates the electromagnetic field at the specific point 503 using the electromagnetic field in each leakage candidate region 601 as a wave source. Specifically, the contribution calculation unit 301 calculates an electromagnetic field created by each leakage candidate region 601 at the specific point 503 using an equivalence theorem.

  Then, the ratio of the electromagnetic field value at the specific point 503 having each leakage candidate region 601 as the wave source to the electromagnetic field value at the specific point 503 having the electromagnetic field of the entire analysis surface 501 as the wave source is calculated, and the calculated value Is a contribution 206 to the far electromagnetic field from each leakage candidate region 601.

  The contribution calculation unit 301 stores the calculated contribution 206 in the hard disk 122. The contribution calculation unit 301 may display the calculated contribution 206 on the monitor 106. The user can know which electromagnetic wave from which leakage candidate area 601 strongly affects the specific point 503 by comparing the calculated contribution values. Therefore, the user can take effective noise countermeasures. The user can efficiently improve the shielding performance of the shielding structure by preferentially taking measures against noise in the leakage candidate region 601 that strongly affects the specific point 503.

  Above, description of the determination method of the contribution to the distance of the electromagnetic field which leaks from the slit 302 of the metal structure 301 concerning this Embodiment is complete | finished.

(3. Analysis process (2))
Hereinafter, a method for determining the degree of contribution to the far electromagnetic field by treating the connection part of the parts of the metal structure 301 as a leakage point of electromagnetic waves will be described. According to this method, although there is no gap between components in the mechanism design, it is possible to know the influence of a connection portion that actually has a gap.

  In this method, as shown in FIG. 7, the contribution degree calculation unit 220 is configured so that a gap is generated between the metal structure 301 and the chassis 303 at the connection portion 701 between the metal structure 301 and the chassis 303. The position of the metal structure 301 set in the data 200 is moved. This movement creates an opening 702.

  The means for providing the opening 702 related to the connection portion 701 is not limited to the movement of the position of the metal structure 301. For example, a means such as deforming the metal structure 301 so as to provide the opening 702 in the connection portion 701 may be used.

  The contribution calculation unit 220 sets the projection area on the analysis surface 501 of the slit 302 in the metal structure 301 as the leakage candidate area 601 by the same method as described above. Further, as shown in FIG. 8, similarly to the setting of the leakage candidate region 601 corresponding to the slit 302, the projection region of the region of the opening 702 onto the analysis surface 501 is set as the electromagnetic wave leakage candidate regions 801a and 801b.

  The contribution degree calculation unit 220 calculates the contribution degree of each leakage candidate area using the same method as described above. That is, the contribution calculation unit 220 calculates an electromagnetic field at a specific point with each leakage candidate region 601 and 801 as a wave source, and calculates the contribution of each leakage candidate region to the far electromagnetic field.

  According to this method, although the user does not cause the far electromagnetic field by design, the user can actually identify the leaking part that affects the far electromagnetic field, and efficiently identify the part that requires EMI countermeasures. it can.

(4. Implementation on a computer)
With reference to FIG. 9, the evaluation process of the shielding structure which concerns on this Embodiment is demonstrated. FIG. 9 is a flowchart showing the flow of the shielding structure evaluation process according to the present embodiment. The following processing is realized by the CPU 120 operating according to the electromagnetic field analysis program 201 and the contribution calculation program 202 stored in the hard disk 122. Moreover, the procedure demonstrated below is only an example, For example, you may replace a step suitably.

  First, in step S <b> 901, the CPU 120 reads the CAD data 200 and the analysis condition 203 from the hard disk 122.

  Next, in step S902, the CPU 120 creates an analysis model 204 based on the CAD data 200 and the analysis conditions 203 read in step S901. Then, the CPU 120 stores the created analysis model 204 in the hard disk 122.

  Next, in step S903, the CPU 120 reads the analysis model 204, obtains electromagnetic field information (amplitude and phase) at each point on the analysis surface 501 by the FDTD method or the like, and stores it as the electromagnetic field analysis result 205 in the hard disk 122.

  When there is actually a shielding structure having the wave source 401 inside, it is possible to measure the electromagnetic field at each point on the measurement surface (corresponding to the analysis surface 501) surrounding the shielding structure. In this case, the CPU 120 may acquire an actual electromagnetic field measurement result instead of the analysis result 205 and store it in the hard disk 122. For example, the CPU 120 acquires the measurement result by the electromagnetic field measurement device via the communication interface 105.

  Next, in step S904, the CPU 120 obtains electromagnetic field information in the observation region 502 from the electromagnetic field information on the analysis surface 501 acquired in step S903.

  Next, in step S <b> 905, the CPU 120 determines the specific point 503 in the observation region 502 based on the electromagnetic field information of the observation region 502 and the conditions for determining the specific point included in the analysis condition 203. For example, the CPU 120 sets a specific point 503 at a point where the electromagnetic field value exceeds a value determined by a standard such as VCCI or a point at which the electromagnetic field value is maximum or maximum.

  Next, in step S <b> 906, the CPU 120 projects the slit area of the shielding structure onto the analysis surface 501 and sets it as an electromagnetic wave leakage candidate area 601. When there is a joint where a plurality of parts of the shielding structure are in contact with each other by design, the CPU 120 moves the arrangement of the parts of the shielding structure to create an opening between the contacting parts, and to the analysis plane 501 of the opening. Is set as a leakage candidate area 801. Note that the method of setting the opening is not limited to the movement of the position of the structure. For example, the shielding structure may be modified so that an opening is provided in the connection portion.

  Next, in step S907, the CPU 120 calculates an electromagnetic field at a specific point with the leakage candidate area as a wave source based on the electromagnetic field information of each leakage candidate area.

  Finally, in step S908, the CPU 120 obtains the contribution 206 of the leakage candidate region to the far electromagnetic field, which is the ratio of the electromagnetic field value calculated in step S907 to the electromagnetic field value obtained in step S904. Store in the hard disk 122.

  As described above, the simulation program according to the present embodiment performs an analysis process of the influence of the shielding structure on the far field. In other words, the simulation program according to the present embodiment performs the performance of the shielding structure having an opening (the opening of the slit or the connection portion) on the projection area onto the surface set around the shielding structure of the opening. As a leakage candidate area, the degree of contribution of each leakage candidate area to a specific point, that is, the influence on the specific point is analyzed. The user can utilize the analysis result for EMI countermeasures. Based on the analysis result, the user can efficiently identify a location that greatly affects the far electromagnetic field in the shielding structure.

  Note that when the specific point is determined in advance, the CPU 120 can omit the process of step S905. Moreover, CPU120 should just obtain | require the electromagnetic field of a specific point instead of covering all the observation areas 502 in step S904.

  Further, the contribution degree of the leakage candidate region may be obtained over the entire observation region 502 without obtaining the specific point. However, as described above, it is possible to reduce the amount of calculation by obtaining a specific point and calculating the contribution of the specific point.

  Further, the contribution calculation unit 220 may obtain the electromagnetic field value itself created in the observation region 502 by the leakage candidate region instead of the contribution as an influence of the leakage candidate region on the observation region 502. In this case, the CPU 120 can omit the processes of step S904 and step S908. However, it is easier for the user to grasp the influence of each leakage candidate area on the observation area 502 by the contribution degree than the electromagnetic field value itself.

  The embodiment disclosed this time should be considered as illustrative in all points and not restrictive. The scope of the present invention is defined by the terms of the claims, rather than the description above, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.

It is the figure which showed the structure of the computer 100 which runs the simulation program which concerns on this Embodiment with the block diagram. 2 is a block diagram showing a functional configuration of a CPU 120. FIG. 3 is a bird's-eye view of a metal structure 301. FIG. It is sectional drawing which looked at the metal structure 301 from the side surface. It is a figure for demonstrating an analysis surface, an observation area | region, and a specific point. It is a figure for demonstrating the setting of a leakage candidate area | region, and calculation of a contribution degree. It is a figure for demonstrating an example of the method of setting opening to the connection part of the components of a shielding structure. It is a figure which shows the leakage candidate area | region corresponding to a slit, and the leakage candidate area | region corresponding to the opening of a connection part. It is the flowchart which showed the flow of the evaluation process of the shielding structure which concerns on this Embodiment.

Explanation of symbols

  100 computer, 101 computer main body, 102 bus, 103 FD drive, 104 optical disk drive, 105 communication interface, 106 monitor, 107 keyboard, 108 mouse, 120 CPU, 121 memory, 122 hard disk, 200 CAD data, 201 electromagnetic field analysis program, 202 contribution calculation program, 203 analysis condition, 204 analysis model, 205 electromagnetic field analysis result, 206 contribution, 210 electromagnetic field analysis unit, 211 model creation unit, 212 analysis execution unit, 220 contribution calculation unit, 301 metal structure , 302 Slit, 401 Wave source, 501 Analysis plane, 502 Observation plane, 503 Specific point, 601 Leakage candidate area, 701 Connection, 702 Opening, 801a, 801b Leakage candidate area.

Claims (7)

An electromagnetic wave shielding structure performance evaluation apparatus for evaluating the performance of an electromagnetic wave shielding structure surrounding an electromagnetic wave generation source,
A storage unit for storing an analysis model of a space including the electromagnetic wave generation source and the electromagnetic wave shielding structure;
On the reference surface surrounding the electromagnetic shielding structure, an electromagnetic field acquisition unit that sets a leakage candidate region corresponding to the opening of the electromagnetic shielding structure and acquires electromagnetic field information of the leakage candidate region;
Based on the analysis model and the electromagnetic field information of the leakage candidate region, the electromagnetic field of the leakage candidate region is used as a wave source, and the aperture contribution is an electromagnetic field in an observation region farther from the electromagnetic shielding structure than the reference plane. An apparatus for evaluating the performance of an electromagnetic wave shielding structure, comprising: a contribution calculation unit that calculates an electromagnetic field.   2. The electromagnetic wave shielding structure performance evaluation apparatus according to claim 1, wherein the electromagnetic field acquisition unit sets a projection area of the area of the opening on the reference plane as the leakage candidate area. The electromagnetic field acquisition unit further acquires electromagnetic field information on the reference plane,
The contribution calculation unit calculates a reference plane contribution electromagnetic field that is an electromagnetic field in the observation region using the electromagnetic field on the reference plane as a wave source based on the analysis model and electromagnetic field information on the reference plane. The electromagnetic shielding according to claim 1, wherein the degree of contribution of the opening to the electromagnetic field in the observation region, which is a ratio of the value of the opening contribution electromagnetic field to the value of the reference plane contribution electromagnetic field, is calculated. Structure performance evaluation device.   The electromagnetic wave according to claim 3, wherein the contribution calculation unit extracts a specific point where a value of the reference plane contribution electromagnetic field is equal to or greater than a predetermined value in the observation region, and calculates the contribution degree at the specific point. A device for evaluating the performance of shielding structures.   The said electromagnetic field acquisition part is a performance evaluation apparatus of the electromagnetic shielding structure of any one of Claims 1-4 which sets the said opening part in the connection part of the components of the said electromagnetic shielding structure. A method for evaluating the performance of an electromagnetic wave shielding structure surrounding an electromagnetic wave generation source using an arithmetic device including a calculation unit and a storage unit,
The arithmetic unit reads out an analysis model of a space including the electromagnetic wave generation source and the electromagnetic wave shielding structure from the storage unit;
The arithmetic unit setting a leakage candidate region corresponding to an opening of the electromagnetic shielding structure on a reference plane surrounding the electromagnetic shielding structure; and
The arithmetic unit obtaining electromagnetic field information of the leakage candidate region;
Based on the analysis model and the electromagnetic field information of the leakage candidate area, the arithmetic unit uses an electromagnetic field of the leakage candidate area as a wave source, and electromagnetic waves in an observation area farther from the electromagnetic shielding structure than the reference plane A method for evaluating the performance of an electromagnetic wave shielding structure, comprising: calculating an aperture-contributing electromagnetic field that is a field. A performance evaluation program for an electromagnetic shielding structure for causing a computing device including a computation unit and a storage unit to perform performance evaluation of the electromagnetic shielding structure surrounding the electromagnetic wave generation source,
Reading an analysis model of a space including the electromagnetic wave generation source and the electromagnetic wave shielding structure from the storage unit;
On the reference plane surrounding the electromagnetic shielding structure, setting a leakage candidate region corresponding to the opening of the electromagnetic shielding structure;
Obtaining electromagnetic field information of the leakage candidate region;
Based on the analysis model and the electromagnetic field information of the leakage candidate region, the electromagnetic field of the leakage candidate region is used as a wave source, and the aperture contribution is an electromagnetic field in an observation region farther from the electromagnetic shielding structure than the reference plane. A program for evaluating the performance of an electromagnetic wave shielding structure, which causes the calculation unit to execute a step of calculating an electromagnetic field.

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