Electromagnetic shielding

Abstract

An electromagnetic shield (10) comprises: several substrates (11), each having one or more conductors (12), wherein of the several substrates (11) adjacent substrates (11) are held such that a distance between a conductor (12) of one of the adjacent substrates (11) and a conductor (12) of the other of the adjacent substrates (11) changes due to disturbances that are naturally present around the adjacent substrates (11).

Description

Technical field

[0001] The present disclosure relates to electromagnetic shielding. State of the art

[0002] There is a general concern about information leaks due to the interception of electromagnetic waves. For example, there is concern about eavesdropping on communications using an electromagnetic wave of a specific frequency used for wireless communication, and about eavesdropping on information within a device (for example, if a monitor is provided, an image displayed by it, or the like) using an electromagnetic wave of a specific frequency unintentionally emitted by an electronic device (so-called electromagnetic noise) (so-called TEMPEST, Transient Electromagnetic Pulse Emanation Standard).

[0003] As a remedy against information leakage, a method for reducing the leakage of an electromagnetic wave to the outside of a building is known by attaching an electromagnetic shield to a wall, window, or the like of a building. For example, patent literature 1 discloses a conventional electromagnetic shield. List of citations from patent literature

[0004] Patent literature 1: JP 2017 - 188 516 A Brief description of the invention Technical task

[0005] The electromagnetic shielding disclosed in patent reference 1 enables the transmission or shielding of electromagnetic waves by means of an elastic structure. In the electromagnetic shielding disclosed in patent reference 1, an electromagnetic wave from a radio wave transmitter is shielded in a state where the elastic structure is not elastically deformed. Conversely, in the state where the elastic structure is elastically deformed, the electromagnetic wave from the radio wave transmitter is transmitted. Therefore, in order to transmit or shield the electromagnetic wave in the electromagnetic shielding disclosed in patent reference 1, it is necessary to artificially control the elastic structure.As a result, the control may become adversely complicated in a case where the electromagnetic shielding disclosed in patent literature 1 is used to try to prevent the leakage of information due to the interception of electromagnetic waves.

[0006] The present invention was made to solve the aforementioned adverse problem, and it is an object of the invention to provide an electromagnetic shield capable of modulating an electromagnetic wave without requiring artificial control. Solution to the task

[0007] An electromagnetic shield according to the present disclosure comprises: several substrates, each having one or more conductors, and substrates adjacent to each other are held by the several substrates in such a way that a distance between a conductor of one of the adjacent substrates and a conductor of the other of the adjacent substrates changes due to disturbances that are naturally present around the adjacent substrates. Advantageous effects of the invention

[0008] According to the present disclosure, electromagnetic waves can be modulated without requiring artificial control. Brief description of the drawings Fig. Figure 1 is a perspective view of an electromagnetic shield according to a first embodiment. Fig. 2 is an enlarged view of the main part of Fig. 1. Fig. Figure 3 is a concept diagram of the change in the frequency characteristic of the complex transmission coefficient and is a diagram showing the change in the absolute value of the complex transmission coefficient. Fig. Figure 4 is a concept diagram of the change in the frequency characteristic of the complex transmission coefficient and is a diagram showing the change in the argument of the complex transmission coefficient. Fig. Figure 5 is a perspective view of an electromagnetic shield according to a second embodiment. Fig. Figure 6 is an enlarged view of the main part of Fig. 5. Fig. Figure 7 is a perspective view of an electromagnetic shield according to a third embodiment. Fig. Figure 8 is an enlarged view of the main part of Fig. 7. Fig. Figure 9 is a perspective view of an electromagnetic shield according to a fourth embodiment. Fig. Figure 10 is an enlarged view of the main part of Fig. 9. Fig. Figure 11 is a perspective view of an electromagnetic shield according to a fifth embodiment. Fig. Figure 12 is an enlarged view of the main part of Fig. 11. Description of the embodiments

[0009] In order to describe the present disclosure precisely, embodiments for carrying out the present disclosure are described below together with the accompanying drawings. First embodiment

[0010] An electromagnetic shield 10 according to a first embodiment is described with reference to Fig. 1, Fig. 2, Fig. 3 to Fig. 4 described.

[0011] First, the structure of the electromagnetic shielding 10 is described with reference to Fig. 1 and Fig. 2 described. Fig. Figure 1 is a perspective view of an electromagnetic shield 10 according to the first embodiment. Fig. 2 is an enlarged view of the main part of Fig. 1.

[0012] A in Fig. 1 The orthogonal coordinate system of a three-dimensional space shown in the electromagnetic shielding 10 is defined by three x-, y- and z-axes that are perpendicular to each other in space. Fig. Figure 1 is an example where the longitudinal direction of the electromagnetic shield 10 is set as the x-axis, the lateral direction (or width direction) of the electromagnetic shield 10 is set as the y-axis, and the vertical direction (or thickness direction) of the electromagnetic shield 10 is set as the z-axis. The arrows of the x-axis, y-axis, and z-axis indicate the respective positive direction.

[0013] The in Fig. The electromagnetic shield 10 shown in Figure 1 is provided in such a way that it separates, for example, the inside from the outside of a building. The electromagnetic shield 10 has a flat inner surface 10a facing the interior of the building and a flat outer surface 10b facing the exterior of the building. The inner surface 10a and the outer surface 10b are arranged parallel to each other. Note that, unlike on a building, the electromagnetic shield 20 can be provided on a mobile object such as a vehicle, a train, or an aircraft.

[0014] In this example, a device is located inside the building that emits an electromagnetic wave containing information that must be prevented from leaking out. This device could be, for example, a wireless device emitting an electromagnetic wave for wireless communication, an electronic device emitting electronic noise, or something similar. In some cases, a receiving device capable of receiving and intercepting the electromagnetic wave, including the information, is located outside the building.

[0015] As in Fig. As shown in Figure 1, the electromagnetic shield 10 incorporates several substrates 11. All substrates 11 are arranged between the inner surface 10a and the outer surface 10b of the electromagnetic shield 10. The electromagnetic shield 10 is configured by forming a step parallel to an xy-plane from several substrates 11 arranged in the x-axis direction and several substrates 11 arranged in the y-axis direction, and by stacking several steps in the z-axis direction. Fig. 1 includes a step parallel to the xy-plane, three substrates 11 arranged in the x-axis direction, and three steps stacked in the z-axis direction.

[0016] All substrates 11 have the same shape and are arranged periodically. One substrate, for example, has a rectangular shape. A substrate 11 contains one or more conductors 12. Furthermore, all conductors 12 have the same shape and are arranged periodically within a substrate. One conductor 12, for example, has a rectangular shape.

[0017] Fig. Figure 1 is an example in which a substrate 11 contains four conductors 12. Furthermore, although the substrate 11 and the conductor 12 are rectangular, their shapes are not limited to this. Moreover, the shapes of the substrate 11 and the conductor 12 need not be the same. For example, the substrate 11 and the conductor 12 can have a round shape, a rhombus shape, a triangular shape, or the like.

[0018] As in Fig. 1 and Fig. As shown in Figure 2, in the electromagnetic shield 10, substrates 11 adjacent to one another in the x-axis, y-axis, or z-axis direction are held such that the distance between their conductors 12 changes due to a disturbance that is naturally present around the electromagnetic shield 10 (around the substrates 11). In particular, the substrates 11 adjacent to one another in the x-axis, y-axis, or z-axis direction are connected by an elastic body. Fig. 1 and Fig. Figure 2 are examples in which the elastic body is a spring 13. A first end of a spring 13 is connected to one substrate 11 of two adjacent substrates 11, and a second end of the spring 13 is connected to the other substrate 11.

[0019] Note that the disturbances naturally present around the electromagnetic shield 10 include, for example, vibration, wind, sound, or the like. The elastic body can be made of rubber.

[0020] In this example, substrates 11 adjacent to each other in the x-axis direction are arranged at intervals of distance D1 in a state where a spring 13 is neither stretched nor compressed. Furthermore, substrates 11 adjacent to each other in the y-axis direction are arranged at intervals of distance D2 in a state where a spring 13 is neither stretched nor compressed. Finally, substrates 11 adjacent to each other in the z-axis direction are arranged at intervals of distance D3 in a state where a spring 13 is neither stretched nor compressed. The distances D1, D2, and D3 are distances between conductors 12.

[0021] Therefore, because the electromagnetic shield 10 has the structure described above and adjacent substrates 11 are connected by a spring 13, the substrates 11 also vibrate with vibration generated in the electromagnetic shield 10, and with vibration generated in the building in which the electromagnetic shield 10 is installed.

[0022] The building's vibration occurs in connection with natural phenomena such as wind or sound, or artificial phenomena such as the movement of a person or mobile object outside the building. The vibration of the electromagnetic shield 10 is also generated by wind pressure or sound pressure exerted directly on the electromagnetic shield 10. Such natural and artificial phenomena occur naturally and are not artificially controlled for the purpose of generating vibration in the electromagnetic shield 10.

[0023] Furthermore, because these vibrations are generated by various contributing factors, their magnitude, frequency, and direction of generation vary irregularly depending on the installation position of the electromagnetic shield 10 and the time period. That is, the multiple substrates 11 contained within the electromagnetic shield 10 vibrate randomly depending on the time period and installation position, without requiring a power source.

[0024] In this way, the distances D1, D2, and D3 between the adjacent substrates 11 also vary randomly with the temporally and spatially random vibration of the substrates 11. At this point, a local complex transmission coefficient in a specific region of the electromagnetic shield 10 depends on the specific distances D1, D2, and D3 in that specific region. Note that the local complex transmission coefficient indicates the degree of change in the amplitude and phase of an electromagnetic wave when the electromagnetic wave is transmitted through the electromagnetic shield 10.

[0025] Next, the points described above will be discussed with reference to Fig. 3 and Fig. 4 described.

[0026] Fig. Figure 3 is a conceptual diagram of a change in the frequency characteristic of the complex transmission coefficient and is a diagram showing the change in the absolute value of the complex transmission coefficient (in other words, the transmission amplitude of an electromagnetic wave). Fig. Figure 4 is a conceptual diagram of the change in the frequency characteristic of the complex transmission coefficient and is a diagram that shows the change in the argument of the complex transmission coefficient (in other words, the transmission phase of an electromagnetic wave). Note that the in Fig. 3 and Fig. The frequency characteristics shown in Figure 4, I, II and III, were obtained by randomly extracting three predetermined combinations of two or more values ​​from the values ​​of the distances D1, D2 and D3.

[0027] As in Fig. As shown in Figure 3, when the distances D1, D2, and D3 change, the absolute value of the complex transmission coefficient changes depending on the magnitude of the frequency. For example, in a case where the frequency of an electromagnetic wave transmitted through the electromagnetic shield 10 is f1, the amplitude of the electromagnetic wave transmitted through the electromagnetic shield 10 varies for each of the frequency characteristics I, II, and III.

[0028] As in Fig. As shown in Figure 4, when the distances D1, D2, and D3 change, the argument of the complex transmission coefficient changes depending on the magnitude of the frequency. For example, in a case where the frequency of an electromagnetic wave transmitted through the electromagnetic shield 10 is f1, the transmission phase of the electromagnetic wave transmitted through the electromagnetic shield 10 varies for each of the frequency characteristics I, II, and III.

[0029] Therefore, the electromagnetic wave incident on the electromagnetic shield 10 leaks out to the outside of the building after the transmission amplitude and transmission phase change depending on the transmission time and transmission position. In other words, the electromagnetic wave incident on the electromagnetic shield 10 is modulated depending on the transmission time and transmission position and leaks out to the outside of the building.

[0030] Therefore, when an electromagnetic wave used for wireless communication and an electromagnetic wave (electromagnetic noise) emitted by an electronic device encounter the electromagnetic shield 10, each of the electromagnetic waves is randomly modulated in time and space by the electromagnetic shield 10. Consequently, the information contained in the electromagnetic wave becomes different from the original information before the electromagnetic wave was modulated and then leaks out of the building.

[0031] Therefore, the electromagnetic shield 10 is able to modulate the transmitted electromagnetic wave through disturbances such as vibration, wind, and sound, which are naturally present around the electromagnetic shield 10. As a result, even if a person listening to the electromagnetic wave outside the building improves their receiver sensitivity, the electromagnetic shield 10 is able to prevent the information contained in the original electromagnetic wave from being intercepted.

[0032] Note that the substrates 11 and the conductors 12 need not be arranged periodically. Furthermore, the characteristics of the springs 13 need not be the same. In this case, the randomness of the modulation on an electromagnetic wave transmitted through the electromagnetic shield 10 can be further increased.

[0033] As described above, the electromagnetic shield 10 according to the first embodiment comprises the plurality of substrates 11, each containing one or more conductors 12. Adjacent substrates 11 are held such that the distance between a conductor 12 of one of the adjacent substrates 11 and a conductor 12 of the other adjacent substrates 11 changes due to disturbances naturally present around the adjacent substrates. Therefore, the electromagnetic shield 10 is able to modulate electromagnetic waves without requiring artificial control. Second embodiment

[0034] An electromagnetic shield 20 according to a second embodiment is now described with reference to Fig. 5 and Fig. 6 described. Fig. Figure 5 is a perspective view of an electromagnetic shield 20 according to the second embodiment. Fig. Figure 6 is an enlarged view of the main part of Fig. 5.

[0035] The in Fig. The electromagnetic shield 10 shown in the first embodiment is designed to modulate electromagnetic interference caused by disturbances such as vibration, wind, or sound pressure by providing an elastic body between adjacent substrates 11. On the other hand, the shield modulates the electromagnetic interference caused by disturbances such as vibration, wind, or sound pressure. Fig. 5 electromagnetic shielding 20 shown according to the second embodiment provides electromagnetic shielding against disturbances such as wind by assembling several substrates 24 into a propeller shape.

[0036] As in Fig. As shown in Figure 5, the electromagnetic shield 20 has a flat inner surface 20a facing the interior of a building and a flat outer surface 20b facing the exterior of the building. The inner surface 20a and the outer surface 20b are arranged parallel to each other. The electromagnetic shield 20 further comprises several fastening components 21 and several propellers 22. All fastening components 21 and all propellers 22 are arranged between the inner surface 20a and the outer surface 20b. The xy-plane, the inner surface 20a, and the outer surface 20b represent reference planes.

[0037] The mounting components 21 are, for example, attached to the side of the outer surface 20b. One mounting component 21 has a wave-like shape and is arranged such that it extends in the y-axis direction. One or more propellers 22 are rotatably mounted by each of the mounting components 21. Fig. Figure 5 is an example in which three fastening components 21 are provided and three propellers 22 are rotatably held by each of the fastening components 21.

[0038] As in Fig. 5 and Fig. As shown in Figure 6, a propeller 22 includes, for example, a rotating shaft 23, substrates 24, and conductors 25. The in Fig. The 6 arrows shown indicate the direction of rotation of the propeller 22.

[0039] The rotating shaft 23 is arranged such that it is orthogonal to the longitudinal direction of the mounting component 21. The rotating shaft 23 is also arranged such that it extends in the Z-axis direction. The proximal end of the rotating shaft 23 is rotatably held by the mounting component 21, such that its axial center forms the pivot point. Conversely, the distal end of the rotating shaft 23 is a free end. The rotating shaft 23 has several branch shafts 23a. Each of the branch shafts 23a extends radially from the distal end of the rotating shaft 23.

[0040] A substrate 24 is provided at the distal end of each of the branch shafts 23a. The substrates 24 represent blades of the propeller 22. The substrates 24 are arranged such that their front and rear surfaces are inclined with respect to the xy-plane. All substrates 24 have the same shape. For example, the substrates 24 have a rectangular shape.

[0041] A substrate 24 contains several conductors 25. All conductors 25 have the same shape and are arranged periodically on the substrate 24. The conductors 25 have, for example, a rectangular shape. Furthermore, each conductor 25 is positioned on the substrate 24 such that its front surface is inclined with respect to the xy-plane.

[0042] This means that the substrates 24 are arranged at constant intervals around the axial center of the rotating shaft 23 such that the conductors 25 are inclined with respect to the xy-plane, which serves as the reference plane. Therefore, a substrate 24 is rotatable such that the distances between the conductors 25 of substrate 24 and the conductors 25 of the other substrates 24 held by the rotating shaft 23 change due to disturbances that naturally occur around the electromagnetic shield 20 (around the substrates 24). Note that the disturbance naturally occurring around the electromagnetic shield 20 is, for example, wind or the like.

[0043] Fig. Figure 5 is an example where a propeller 22 includes four substrates 24, each having eight conductors 25. Note that for electromagnetic shielding 20, the number of installed propellers 22, the number of substrates 24 installed on a propeller 22, and the number of conductors 25 installed on a substrate 24 can be adjusted depending on the circumstances.

[0044] Therefore, when the wind hits the substrates 24 representing the blades of the propellers 22, the propellers 22 rotate if the electromagnetic shield 20 has the structure described above.

[0045] The wind blowing against the electromagnetic shield 20 is generated in conjunction with a natural phenomenon such as wind or rain, or an artificial phenomenon such as the movement of a person or a mobile object outside the building. Furthermore, if the electromagnetic shield 20 is attached to a mobile object, the (moving) wind generated by the moving object also acts upon the electromagnetic shield 20. Such natural and artificial phenomena occur naturally and are not artificially controlled for the purpose of blowing wind onto the electromagnetic shield 20.

[0046] Furthermore, the directions and speeds of the phenomenon are influenced by various conditions, such as weather conditions and the arrangement of surrounding objects, which contribute in a complex manner. In a case where the electromagnetic shield 20 is mounted on a mobile object, the speed and direction of travel of the mobile object also contribute to the above. Therefore, the direction and speed of the wind blowing on the electromagnetic shield 20 change irregularly depending on the installation position of the electromagnetic shield 20 and the time interval. That is, the propellers 22 contained in the electromagnetic shield 20 rotate at random speeds depending on the time interval and the installation position, without requiring a power source.

[0047] As described above, the rotation of the propellers 22 occurs randomly in time and space, causing the distance, angle of attack, and overlap area to change randomly between conductors 25 of substrates 24 on one propeller 22 and conductors 25 of substrates 24 on a propeller 22 adjacent to the propeller 22. At this point, a local complex transmission coefficient in a specific region of the electromagnetic shield 20 depends on the distance, angle of attack, and overlap area in that specific region.

[0048] Therefore, the electromagnetic wave incident on the electromagnetic shield 20 leaks out to the outside of the building after the transmission amplitude and transmission phase change depending on the transmission time and transmission position. In other words, the electromagnetic wave incident on the electromagnetic shield 10 is modulated depending on the transmission time and transmission position and leaks out to the outside of the building.

[0049] Therefore, when an electromagnetic wave used for wireless communication and an electromagnetic wave (electromagnetic noise) emitted by an electronic device encounter the electromagnetic shield 20, each of the electromagnetic waves is randomly modulated in time and space by the electromagnetic shield 20. Consequently, the information contained in the electromagnetic wave becomes different from the original information before the electromagnetic wave was modulated and then leaks out of the building.

[0050] Therefore, the electromagnetic shield 20 is able to modulate the transmitted electromagnetic wave through disturbances such as vibration, wind, and sound that are naturally present around the electromagnetic shield 20. As a result, even if a person listening to the electromagnetic wave outside the building improves their receiver sensitivity, the electromagnetic shield 20 is able to prevent the information contained in the original electromagnetic wave from being intercepted.

[0051] Note that the propellers 22 and the conductors 25 need not be arranged periodically. Furthermore, the number of substrates 24 installed on a propeller 22, the number of conductors 25 installed on a substrate 24, the inclination angles of the front and back of the substrates 24 with respect to the xy-plane, the shapes of the substrates 24, and the shapes of the conductors 25 need not be the same. In this case, the randomness of the modulation of an electromagnetic wave transmitted through the electromagnetic shield 10 can be further increased.

[0052] As described above, the electromagnetic shield 20 according to the second embodiment comprises: a substrate 24 with one or more conductors 25; and several rotating shafts 23, each holding the substrate 24 about an axial center in a state in which the conductors 25 are inclined relative to the reference plane, the substrate 24 rotating such that the distance between a conductor 25 of the substrate 24 and a conductor 25 of a substrate 24 held by another rotating shaft 23 changes due to disturbances naturally present around the substrate. Therefore, the electromagnetic shield 20 is able to modulate electromagnetic waves without requiring artificial control. Third embodiment

[0053] An electromagnetic shield 30 according to a third embodiment is now described with reference to Fig. 7 and Fig. 8 described. Fig. Figure 7 is a perspective view of an electromagnetic shield 30 according to the third embodiment. Fig. Figure 8 is an enlarged view of the main part of Fig. 7.

[0054] The in Fig. 1 and Fig. The electromagnetic shields 10 and 20 shown in the first and second embodiments are structured to modulate an electromagnetic wave through disturbances such as vibration, wind, or sound. On the other hand, the electromagnetic shield 30 modulates according to the one shown in Fig. 7. In the third embodiment shown, an electromagnetic wave is transmitted through an electromagnetic field, which is a different physical phenomenon than the ones above.

[0055] As in Fig. As shown in Figure 7, the electromagnetic shield 30 has a flat inner surface 30a facing the interior of a building and a flat outer surface 30b facing the exterior of the building. The inner surface 30a and the outer surface 30b are arranged parallel to each other. The electromagnetic shield 30 further comprises multiple substrates 31, multiple conductors 32, multiple varactors 33, and multiple retaining elements 34. The multiple substrates 31, multiple conductors 32, multiple varactors 33, and multiple retaining elements 34 are arranged between the inner surface 30a and the outer surface 30b.

[0056] The substrates 31 are stacked in the z-axis direction. In this case, the z-axis direction is the stacking direction. The substrates 31 adjacent to each other in the z-axis direction are connected to each other via the retaining elements 34. The retaining elements 34 connect four corners on the back of one of the adjacent substrates 31 to four corners on the front of the other adjacent substrate 31. Therefore, the multiple substrates 31 are stacked at a certain interval by the retaining elements 34. Note that the substrates 31 do not need to be stacked at regular intervals. Furthermore, only one substrate 31 needs to be provided.

[0057] As in Fig. 7 and Fig. As shown in Figure 8, a substrate 31 contains several conductors 32. All conductors 32 have the same shape and are arranged periodically on a substrate 31. In particular, a substrate 31 contains one or more pairs of conductors 32.

[0058] A varactor 33 connects a pair of conductors 32. The varactors 33 are located on the front face of the substrate 31. A varactor 33 acts as a coupling element. The varactors 33 have the characteristic that their electrostatic capacitance changes depending on the applied voltage. Furthermore, the capacitance of the varactors 33, which is a physical property, changes due to disturbances that are naturally present around the electromagnetic shield 30 (around the substrates 31). In this case, the disturbance naturally present around the electromagnetic shield 30 is, for example, an electromagnetic field.

[0059] Fig. Figure 7 shows an example in which two substrates 31 are stacked and twelve conductor pairs 32 are provided for each substrate 31, with each pair being connected by a varactor 33. Note that in the electromagnetic shield 30, the number of stacked substrates 31, the number of conductor pairs 32 provided on a substrate 31, and the number of varactors 33 installed between a pair of conductors 32 can be adapted according to the circumstances.

[0060] Therefore, the electromagnetic shield 30 with the configuration described above generates an electric field and a voltage V1, which is linked to the electric field between a pair of conductors 32 connected by the varactor 33, through an electric field naturally present around the electromagnetic shield 30.

[0061] The naturally occurring electric field around the electromagnetic shield 30 is generated by an electromagnetic wave for wireless communication emitted by a wireless device, an electromagnetic wave emitted by an electronic device (electromagnetic noise), electromagnetic waves from various other devices, electromagnetic waves due to electrostatic discharges caused by the proximity of human bodies or objects, or other sources. Such a phenomenon of generating an electromagnetic field occurs naturally and is not artificially controlled for the purpose of generating the electric field and the voltage V1 associated with the electric field in the electromagnetic shield 30.

[0062] Furthermore, the frequency spectrum, polarization, and arrival direction of each of these electromagnetic waves are determined by various conditions, such as the positional relationships between the electromagnetic wave sources and the electromagnetic shield 30, and the arrangement of objects on the propagation paths of the electromagnetic waves from the radiation sources (devices) to the electromagnetic shield 30, and contribute in a complex manner. Therefore, the frequency spectrum, polarization, and arrival direction of each of these electromagnetic waves change irregularly depending on the installation position of the electromagnetic shield 30 and the time interval. That is, the voltage V1 generated in the electromagnetic shield 30 changes randomly depending on the time interval and the installation position, without requiring a current source.

[0063] As described above, the voltage V1 generated in the electromagnetic shield 30 changes randomly in time and position, which also causes the electrostatic capacitance of the varactors 33 to change randomly. At this point, a local complex transmission coefficient in a specific region of the electromagnetic shield 30 depends on the voltage V1 in that specific region.

[0064] Therefore, the electromagnetic wave incident on the electromagnetic shield 30 leaks out to the outside of the building after the transmission amplitude and transmission phase have changed depending on the transmission time and transmission position. In other words, the electromagnetic wave incident on the electromagnetic shield 30 is modulated depending on the transmission time and transmission position and then leaks out to the outside of the building.

[0065] Therefore, when an electromagnetic wave used for wireless communication and an electromagnetic wave (electromagnetic noise) emitted by an electronic device encounter the electromagnetic shield 30, each of the electromagnetic waves is randomly modulated in time and space by the electromagnetic shield 30. Consequently, the information contained in the electromagnetic wave becomes different from the original information before the electromagnetic wave was modulated and then leaks out of the building.

[0066] Therefore, the electromagnetic shield 30 is able to modulate the transmitted electromagnetic wave by interference such as an electromagnetic wave that is naturally present around the electromagnetic shield 30. As a result, even if a person listening to the electromagnetic wave outside the building improves their receiver sensitivity, the electromagnetic shield 30 is able to prevent the information contained in the original electromagnetic wave from being intercepted.

[0067] Note that the conductors 32 need not be arranged periodically. Additionally, the shapes of the substrates 31, the shapes of the conductors 32, the shapes of the varactors 33, and the characteristics of the varactors 33 need not be the same. In this case, the randomness of the modulation of an electromagnetic wave transmitted through the electromagnetic shield 30 can be further increased.

[0068] As described above, the electromagnetic shield 30 according to the third embodiment comprises: one or more substrates 31, each having one or more pairs of conductors 32; and a varactor 33 that couples the one or more pairs of conductors 32 and whose physical properties change due to a disturbance naturally present around the one or more substrates. Therefore, the electromagnetic shield 30 is able to modulate electromagnetic waves without requiring artificial control. Fourth embodiment

[0069] An electromagnetic shield 40 according to a fourth embodiment is now described with reference to Fig. 9 and Fig. 10 described. Fig. Figure 9 is a perspective view of the electromagnetic shielding 40 according to the fourth embodiment. Fig. Figure 10 is an enlarged view of the main part of Fig. 9. Note that the same symbols are assigned to components that have similar functions to those described in the third embodiment, and their description is omitted.

[0070] For electromagnetic shielding 30 according to the in Fig. In the third embodiment shown in Figure 7, an electromagnetic wave is modulated by an electric field, which is a physical phenomenon. On the other hand, the electromagnetic shield 40 modulates according to the one shown in Figure 7. Fig. In the fourth embodiment shown in Figure 9, an electromagnetic wave is modulated by an electromagnetic field and light, vibration, heat, or the like, which is a different physical phenomenon. That is, the electromagnetic shield 40 according to the fourth embodiment modulates an electromagnetic wave by two different types of physical phenomena.

[0071] As in Fig. As shown in Figure 9, the electromagnetic shield 40 has a flat inner surface 40a facing the interior of a building and a flat outer surface 40b facing the exterior of the building. The inner surface 40a and the outer surface 40b are arranged parallel to each other. The electromagnetic shield 40 further comprises multiple substrates 31, multiple conductors 32, multiple varactors 33, and multiple ambient current-generating elements 41. The multiple substrates 31, multiple conductors 32, multiple varactors 33, and multiple ambient current-generating elements 41 are arranged between the inner surface 40a and the outer surface 40b. The electromagnetic shield 40 is obtained by adding the ambient current-generating elements 41, which serve as coupling elements, to the configuration of the electromagnetic shield 30.

[0072] As in Fig. 9 and Fig. As shown in Figure 10, a pair of conductors 32 is connected by a varactor 33 and an ambient current-generating element 41. The ambient current-generating element 41 is located on the front face of a substrate 31. The ambient current-generating element 41 has the characteristic that the amount of current generated changes depending on the energy source, such as light, vibration, or heat. That is, the amount of energy generated by the ambient current-generating element 41 changes, which is a physical property, due to disturbances that are naturally present around the electromagnetic shield 40 (around the substrate 31). In this case, the disturbance naturally present around the electromagnetic shield 40 is, for example, any kind of light, vibration, or heat.

[0073] Fig. Figure 9 shows an example in which two substrates 31 are stacked, and twelve pairs of conductors 32 are connected, each pair being linked by a varactor 33, and an environmental power generation element 41 is provided for each of the substrates 31. Note that in the electromagnetic shield 40, the number of stacked substrates 31, the number of conductors 32 provided for each substrate 31, the number of installed varactors 33, and the number of environmental power generation elements 41 installed between a pair of conductors 32 can be adapted according to the circumstances.

[0074] The following operation of the electromagnetic shielding 40 is now described for a case in which the environmental power generating elements 41 receive light to produce electricity. The operation is the same even in cases in which the environmental power generating elements 41 produce electricity from received vibrations, heat, or the like.

[0075] Therefore, by having the electromagnetic shield 40 in the configuration described above, an electric field and a voltage V1 associated with the electric field are generated between a pair of conductors 32 connected to a varactor 33, by means of an electromagnetic field naturally present around the electromagnetic shield 40. Additionally, with the electromagnetic shield 40 in the configuration described above, an environmental power-generating element 41 generates current from light naturally present around the electromagnetic shield 40, thereby generating a voltage V2 associated with this current generation between a pair of conductors 32 connected to the environmental power-generating element 41.

[0076] The light naturally present around the electromagnetic shield 40 includes natural phenomena such as sunlight and artificial phenomena such as light emitted from a television screen. Such natural and artificial phenomena occur naturally and are not artificially controlled for the purpose of emitting light towards the electromagnetic shield 40.

[0077] Furthermore, the intensity of the light naturally present around the electromagnetic shield 40 and the voltage V2 generated in the environmental power generation element 41, which depends on the light intensity, are determined by various conditions, such as the positional relationship between the light source and the electromagnetic shield 40, and the arrangement of objects in the light's propagation path from the light source to the electromagnetic shield 40, and contribute in a complex manner. Therefore, the light intensity and the voltage V2 change irregularly depending on the installation position of the electromagnetic shield 40 and the time interval. That is, the voltage V2 generated in the electromagnetic shield 40 changes randomly depending on the time interval and the installation position, without requiring a power source.

[0078] As described above, the amount of current generated by the environmental power-generating elements 41 changes randomly in time and position, which also causes the voltage V2 generated between the pair of conductors 32 to change randomly. At this point, a local complex transmission coefficient in a specific region of the electromagnetic shield 40 depends on the voltage generated in that specific region.

[0079] Therefore, an electromagnetic wave striking the electromagnetic shield 40 leaks out to the outside of the building after the transmission amplitude and transmission phase have changed depending on the transmission time and transmission position. In other words, the electromagnetic wave striking the electromagnetic shield 40 is modulated depending on the transmission time and transmission position and then leaks out to the outside of the building.

[0080] Therefore, when an electromagnetic wave used for wireless communication and an electromagnetic wave (electromagnetic noise) emitted by an electronic device encounter the electromagnetic shield 40, each of the electromagnetic waves is randomly modulated in time and position by the electromagnetic shield 40. Consequently, the information contained in the electromagnetic wave becomes different from the original information before the electromagnetic wave was modulated and then leaks out of the building.

[0081] Therefore, the electromagnetic shield 40 is able to modulate the transmitted electromagnetic wave through disturbances such as light, vibration, and heat that are naturally present around the electromagnetic shield 40. As a result, even if a person listening to the electromagnetic wave outside the building improves their receiver sensitivity, the electromagnetic shield 40 is able to prevent the information contained in the original electromagnetic wave from being intercepted.

[0082] Note that the conductor pairs 32 connected by the varactors 33 and the environmental energy generating elements 41 need not be arranged periodically. Furthermore, the shapes and characteristics of the environmental energy generating elements 41 and the varactors 33 need not be identical. In this case, the randomness of the modulation of an electromagnetic wave transmitted through the electromagnetic shield 40 can be further increased.

[0083] As described above, the electromagnetic shield 40 according to the fourth embodiment comprises: one or more substrates 31, each having one or more pairs of conductors 32; and an ambient current-generating element 41, which couples each of the one or more pairs of conductors 32 and whose physical properties change due to a disturbance naturally present around the substrates. Therefore, the electromagnetic shield 40 is able to modulate electromagnetic waves without requiring artificial control. Fifth embodiment

[0084] An electromagnetic shield 50 according to a fifth embodiment is now described with reference to Fig. 11 and Fig. 12 described. Fig. Figure 11 is a perspective view of the electromagnetic shielding 50 according to the fifth embodiment. Fig. Figure 12 is an enlarged view of the main part of Fig. 11. Note that the same symbols are assigned to components that have similar functions to those described in the third embodiment, and their description is omitted.

[0085] For electromagnetic shielding 30 according to the in Fig. In the third embodiment shown in Figure 7, an electromagnetic wave is modulated by an electric field, which is a physical phenomenon. On the other hand, the electromagnetic shield 50 modulates according to the one shown in Figure 7. Fig. 11 fifth embodiment shown an electromagnetic wave through light, temperature, sound or other physical phenomena.

[0086] As in Fig. As shown in Figure 11, the electromagnetic shield 50 has a flat inner surface 50a facing the interior of a building and a flat outer surface 50b facing the exterior of the building. The inner surface 50a and the outer surface 50b are arranged parallel to each other. The electromagnetic shield 50 further comprises multiple substrates 31, multiple conductors 32, and multiple sensors 51. The multiple substrates 31, multiple conductors 32, and multiple sensors 51 are arranged between the inner surface 40a and the outer surface 40b. Instead of the varactor 33 of the electromagnetic shield 30, the electromagnetic shield 50 has a sensor 51 that serves as a coupling element.

[0087] As in Fig. 11 and Fig. As shown in Figure 12, a pair of conductors 32 is connected by a sensor 51. The sensor 51 is located on the front face of a substrate 31. The sensor 51 detects the intensity of light, temperature, sound pressure, or other parameters and exhibits a characteristic such that its impedance Z changes depending on these parameters. That is, the impedance Z in the sensor 51 changes, which is a physical property, due to disturbances that are naturally present around the electromagnetic shield 50 (around the substrate 31). For example, if the sensor 51 is an optical sensor, the disturbance is light. Alternatively, if the sensor 51 is a temperature sensor, the disturbance is temperature. Furthermore, if the sensor 51 is a sound sensor, the disturbance is sound.

[0088] Fig.Figure 11 shows an example in which two substrates 31 are stacked, and twelve pairs of conductors 32 are provided for each substrate 31, with each pair being connected by a sensor 51. Note that in the electromagnetic shield 50, the number of stacked substrates 31, the number of conductors 32 provided for each substrate 31, and the number of sensors 51 installed between a pair of conductors 32 can be adapted according to the circumstances.

[0089] The following operation of the electromagnetic shielding 50 is now described for a case in which the sensors 51 are optical sensors. The operation is the same even in cases in which the sensors 51 are temperature sensors or sound sensors.

[0090] Therefore, a sensor 51 connecting a pair of conductors 32, in the electromagnetic shield 50 with the configuration described above, detects light naturally present around the electromagnetic shield 50, thereby generating the impedance Z within the sensor 51.

[0091] The light naturally present around the electromagnetic shield 50 includes natural phenomena such as sunlight and artificial phenomena such as light emitted from a television screen. Such natural and artificial phenomena occur naturally and are not artificially controlled for the purpose of emitting light for the electromagnetic shield 50.

[0092] Furthermore, the intensity of naturally occurring light around the electromagnetic shield 50 and the impedance Z generated in the sensor 51 as a function of the light depend on various conditions, such as the positional relationship between the light source and the electromagnetic shield 50, and the arrangement of objects in the light's propagation path from the light source to the electromagnetic shield 50, which contributes to a complex situation. Therefore, the light intensity and the impedance Z change irregularly depending on the installation position of the electromagnetic shield 50 and the time interval. That is, the impedance Z generated in the electromagnetic shield 50 changes randomly depending on the time interval and the installation position.

[0093] As described above, the intensity of the light detected by sensor 51 changes randomly in time and position, which also causes the impedance Z of sensor 51 to change randomly. At this point, a local complex transmission coefficient in a specific region of the electromagnetic shield 50 depends on the impedance Z in that specific region.

[0094] Therefore, an electromagnetic wave striking the electromagnetic shield 50 leaks out to the outside of the building after the transmission amplitude and transmission phase have changed depending on the transmission time and transmission position. In other words, the electromagnetic wave striking the electromagnetic shield 50 is modulated depending on the transmission time and transmission position and then leaks out to the outside of the building.

[0095] Therefore, when an electromagnetic wave used for wireless communication and an electromagnetic wave (electromagnetic noise) emitted by an electronic device encounter the electromagnetic shield 50, each of the electromagnetic waves is randomly modulated in time and position by the electromagnetic shield 50. Consequently, the information contained in the electromagnetic wave becomes different from the original information before the electromagnetic wave was modulated and then leaks out of the building.

[0096] Therefore, the electromagnetic shield 50 is able to modulate the transmitted electromagnetic wave through disturbances such as light, temperature, and sound that are naturally present around the electromagnetic shield 50. As a result, even if a person listening to the electromagnetic wave outside the building improves their reception sensitivity, the electromagnetic shield 50 is able to prevent the information contained in the original electromagnetic wave from being intercepted.

[0097] Note that the pair of conductors 32 connected by the sensors 51 need not be arranged periodically. Furthermore, the shapes and characteristics of the sensors 51 need not be identical. In this case, the randomness of the modulation of an electromagnetic wave transmitted through the electromagnetic shield 50 can be further increased.

[0098] As described above, the electromagnetic shield 50 according to the fifth embodiment comprises: one or more substrates 31, each having one or more pairs of conductors 32; and a sensor 51 that couples the one or more pairs of conductors 32 and whose physical properties change due to a disturbance that is naturally present around the substrates. Therefore, the electromagnetic shield 50 is able to modulate electromagnetic waves without requiring artificial control.

[0099] Note that the present disclosure may include flexible combinations of embodiments, a modification of any component of the embodiments, or the omission of any component of the embodiments within the scope of the disclosure. Commercial applicability

[0100] An electromagnetic shield according to the present disclosure is able to prevent the leakage of information contained in an electromagnetic wave by modulating the electromagnetic wave by means of disturbances naturally present around substrates, and is suitable for use as an electromagnetic shield or the like. Reference symbol list 10, 20, 30, 40, 50 electromagnetic shielding 10a, 20a, 30a, 40a, 50a Inner surface 10b, 20b, 30b, 40b, 50b external surface 11 Substrat 12 ladders 13 spring 21 Fastening component 22 propellers 23 Rotational shaft 23a Branch wave 24 substrate 25 leaders 31 Substrat 32 ladders 33 Varactor 34 Mounting component 41 Ambient power generation element 51 Sensor D1 to D3 distance V1, V2 voltage Z impedance QUOTES INCLUDED IN THE DESCRIPTION

[0000] This list of documents cited by the applicant was automatically generated and is included solely for the reader's convenience. The list is not part of the German patent or utility model application. The DPMA accepts no liability for any errors or omissions. Cited patent literature

[0000] JP 2017 - 188 516 A

[0004]

Claims

[1] Electromagnetic shielding, comprising: Several substrates, each having one or more conductors, wherein of the several substrates adjacent to each other are held such that a distance between a conductor of one of the adjacent substrates and a conductor of the other of the adjacent substrates changes due to disturbances naturally present around the adjacent substrates. [2] Electromagnetic shielding according to claim 1, wherein the adjacent substrates are held over an elastic body. [3] Electromagnetic shielding according to claim 1 or 2, wherein the elastic body is a spring. [4] Electromagnetic shielding according to claim 1 or 2, wherein the elastic body is a rubber. [5] Electromagnetic shielding according to any one of claims 1 to 4, wherein the disturbance is at least one of vibration, wind or sound. [6] Electromagnetic shielding, comprising: a substrate with one or more conductors; and several rotating waves, each holding the substrate around an axial center in a state in which the conductors are inclined with respect to a reference plane, wherein the substrate rotates such that a distance between a conductor of the substrate and a conductor of a substrate held by another rotating wave changes due to disturbances naturally present around the substrate. [7] Electromagnetic shielding according to claim 6, wherein the disturbance is wind. [8] Electromagnetic shielding, comprising: one or more substrates, each comprising one or more conductor pairs; and a coupling component that couples one or more pairs of conductors, wherein the coupling component has a physical property that changes due to a disturbance that is naturally present around one or more substrates. [9] Electromagnetic shielding according to claim 8, wherein the coupling component is a varactor; and a change in the capacity of the varactor due to a disturbance that is naturally present around one or more substrates. [10] Electromagnetic shielding according to claim 9, wherein the interference is a magnetic field. [11] Electromagnetic shielding according to claim 8, wherein the coupling component is an ambient power generation element, and a change in the amount of electricity generated by the surrounding electricity-generating element due to a disturbance that is naturally present around one or more substrates. [12] Electromagnetic shielding according to claim 11, wherein the disturbance is any of light, vibration and heat. [13] Electromagnetic shielding according to claim 8, wherein the coupling element is a sensor, and a change in the sensor's impedance due to a disturbance that is naturally present around one or more substrates. [14] Electromagnetic shielding according to claim 13, wherein the interference is any of light, temperature and sound.

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