Information leakage preventing shielding device

Abstract

A leakage prevention shielding device (100) has a control section that outputs a frequency setting signal that sets a filter frequency for electromagnetic waves radiated from a device (200), and a modulation signal based on a time variation pattern that sequentially indicates a plurality of different transmission characteristics as time passes, and a dynamic electromagnetic wave filter (5a-5c) that is set with the filter frequency by the frequency setting signal from the control section, and is set with the transmission characteristics that differ as time passes by the modulation signal from the control section, the dynamic electromagnetic wave filter (5a-5c) transmitting electromagnetic waves other than the filter frequency set by the frequency setting signal, and having the transmission characteristics that differ as time passes set by the modulation signal for the filter frequency set by the frequency setting signal.

Description

Technical Field

[0001] This invention relates to an information leakage prevention shielding device that prevents information leakage due to electromagnetic waves emitted from information devices and other equipment. Background Technology

[0002] In recent years, as a countermeasure to prevent the leakage of information in a device by receiving and demodulating electromagnetic waves emitted from devices such as information devices, Patent Document 1 discloses an information leakage prevention device that prevents electromagnetic waves from leaking out through a window.

[0003] That is, Patent Document 1 shows a device for preventing information leakage as follows: when receiving an electromagnetic wave emitted from the device, the target frequency to be attenuated is determined, the incident direction of the electromagnetic wave of the determined frequency is determined, a predetermined voltage corresponding to the determined frequency and the determined incident angle is provided to a special structural unit that absorbs the electromagnetic wave of the specific frequency, and the frequency component that is consistent with the higher harmonic component of the dot clock frequency of the leaking electromagnetic wave is attenuated by the special structural unit.

[0004] Existing technical documents

[0005] Patent documents

[0006] Patent Document 1: Japanese Patent Application Publication No. 2016-1796 Summary of the Invention

[0007] The problem that the invention aims to solve

[0008] In the information leakage prevention device shown in Patent Document 1, the frequency component that is consistent with the higher harmonic component of the point clock frequency of the electromagnetic wave emitted from the device is attenuated, thereby reducing the intensity of the leaked electromagnetic wave received by the eavesdropping device. Therefore, there is a problem that even if the leaked electromagnetic wave is weak after being attenuated by the information leakage prevention device, if time is spent trying to eavesdrop during the period of emitting the leaked electromagnetic wave, and the eavesdropped leaked electromagnetic wave is averaged, it is possible to steal information from the leaked electromagnetic wave.

[0009] The present invention was proposed to solve the above-mentioned problems, and its object is to provide an information leakage prevention shielding device that reduces the possibility of information being stolen from electromagnetic waves emitted by a device.

[0010] Methods for solving problems

[0011] The information leakage prevention shielding device of the present invention includes: a control unit that outputs a frequency setting signal for setting the filter frequency of electromagnetic waves emitted from a device and a modulation signal based on a time-varying pattern, wherein the time-varying pattern is used to sequentially indicate a plurality of different transmission characteristics as time passes; and a dynamic electromagnetic wave filter that has its filter frequency set by the frequency setting signal from the control unit and its transmission characteristics that differ as time passes by the modulation signal from the control unit. The dynamic electromagnetic wave filter transmits electromagnetic waves other than the filter frequency set by the frequency setting signal and exhibits transmission characteristics that differ as time passes by the modulation signal for the filter frequency set by the frequency setting signal.

[0012] Invention Effects

[0013] According to the present invention, the effect of preventing information leakage from electromagnetic waves emitted by information devices and other devices can be improved. Attached Figure Description

[0014] Figure 1 This is a schematic diagram showing the state of the information leakage prevention shielding device of Embodiment 1.

[0015] Figure 2 This is a structural diagram showing the information leakage prevention shielding device of Embodiment 1.

[0016] Figure 3 This is a flowchart illustrating the operation of the modulation signal generation unit in the information leakage prevention shielding device of Embodiment 1.

[0017] Figure 4 This is a graph showing the relationship between time and transmission phase in the numerical example 1 of the modulation method example 2 used to illustrate the information leakage prevention shielding device of embodiment 1.

[0018] Figure 5 This is a graph showing the result obtained by calculating the relationship between higher harmonics and the amplitude of the leaked electromagnetic wave in the numerical example 1 of the modulation method example 2 used to illustrate the information leakage prevention shielding device of embodiment 1.

[0019] Figure 6 This is a graph showing the amplitude of the leakage electromagnetic wave relative to the number of modulation method example 2 in the information leakage shielding device for illustrating embodiment 1.

[0020] Figure 7 This is a graph showing the amplitude of the leaked electromagnetic wave relative to the number of times, for example 3 of the modulation method example 2 used to illustrate the information leakage shielding device of embodiment 1.

[0021] Figure 8This is a structural diagram showing the information leakage prevention shielding device of Embodiment 2.

[0022] Figure 9 This is a structural diagram showing the information leakage prevention shielding device of Embodiment 3.

[0023] Figure 10 This is a structural diagram showing the information leakage prevention shielding device of Embodiment 4. Detailed Implementation

[0024] Implementation Method 1

[0025] use Figures 1 to 7 The information leakage prevention shielding device 100 of Embodiment 1 will be described.

[0026] like Figure 1 As shown, the information leakage prevention shielding device 100 is installed on the structure 400 that separates the information equipment and other equipment 200 from the eavesdropping device 300.

[0027] Device 200 is a listening device that may be the target of eavesdropping, and in Embodiment 1 it is envisioned as a monitor. However, the monitor is not limited to one unit, and multiple units may exist. In addition, besides monitors, the information leakage prevention shielding device 100 of Embodiment 1 can also be applied to devices that intentionally or unintentionally emit electromagnetic waves, such as wireless communication devices and printers.

[0028] In the description of this invention, the information being monitored is mainly described in terms of the image information of the monitor. However, the information being monitored can also be the content of wireless communication contained in the radio waves emitted by the wireless communication device, the printing information of the printer, etc. In short, the information leakage prevention shielding device of this invention can be applied to information that is intentionally or unintentionally emitted as radio waves.

[0029] The eavesdropping device 300 is an eavesdropping device consisting of an antenna, a receiving device, etc., used by the eavesdropper.

[0030] Structure 400 is a shell or cover surrounding equipment 200, curtains or windows of a building housing equipment 200, or other structures.

[0031] like Figure 2 As shown, the information leakage prevention shielding device 100 includes an electromagnetic wave detection unit 1, a storage unit 2, a modulation signal generation unit 3, a control signal output unit 4, and a first dynamic electromagnetic wave filter 5a to a third dynamic electromagnetic wave filter 5c.

[0032] Regarding the information leakage prevention shielding device 100, it is described as having three dynamic electromagnetic wave filters 5, namely the first dynamic electromagnetic wave filter 5a to the third dynamic electromagnetic wave filter 5c. However, it may also have one dynamic electromagnetic wave filter 5, two dynamic electromagnetic wave filters 5, or four or more dynamic electromagnetic wave filters 5.

[0033] In addition, in the following description, in particular, where it is not necessary to separately define the first dynamic electromagnetic wave filter 5a to the third dynamic electromagnetic wave filter 5c, the additional reference numerals a to c will be omitted to avoid confusion.

[0034] The electromagnetic wave detection unit 1 detects electromagnetic waves (emissions, radiants) containing image information emitted from the device 200 and outputs the frequency of the detected electromagnetic waves to the modulation signal generation unit 3.

[0035] Furthermore, the electromagnetic wave detection unit 1 extracts, for example, background information from the electromagnetic waves emitted from the periphery of the device 200, detects the frequency of background noise from the background information, and outputs the detected frequency of background noise to the modulation signal generation unit 3.

[0036] The electromagnetic wave detection unit 1 performs the actions of detecting the frequency of electromagnetic waves and extracting information features from electromagnetic waves using generally known techniques.

[0037] The frequency of the electromagnetic waves emitted by the slave device 200 detected by the electromagnetic wave detection unit 1 is set to the frequency that contains image information within the electromagnetic waves emitted by the slave device 200. Specifically, it is equivalent to the frequency of the dot clock frequency, which is called the image information, and the frequency of its higher harmonics, which are integer multiples of the frequency.

[0038] In the following description, the frequency of the electromagnetic waves emitted from the device 200 detected by the electromagnetic wave detection unit 1 will be set to the frequency of the electromagnetic waves emitted from the device 200.

[0039] Furthermore, if the device 200 for preventing information leakage is known in advance, the frequency of the electromagnetic waves emitted from the device 200 can be pre-stored in the storage unit 2, eliminating the need for the electromagnetic wave detection unit 1.

[0040] Storage unit 2 stores modulation methods that switch to multiple different transmission phases over time.

[0041] The modulation schemes stored in storage unit 2 are modulation scheme 1 to modulation scheme 5. Modulation schemes 1 to 5 will be described in detail later.

[0042] Furthermore, the modulation method is not limited to modulation method 1 to modulation method 5. In short, it is a modulation method in the dynamic electromagnetic wave filter 5 that sequentially switches the transmission amplitude and transmission phase, i.e., the transmission characteristics, according to the set filter frequency over time.

[0043] The modulation signal generation unit 3 receives the frequency of the electromagnetic wave emitted from the device 200 detected by the electromagnetic wave detection unit 1 or the frequency of the electromagnetic wave emitted from the device 200 stored in the storage unit 2, and determines the filter frequency for the electromagnetic wave emitted from the device 200. In addition, it reads out at least one of the modulation modes stored in the storage unit 2, namely modulation mode 1 to modulation mode 5, and generates a time variation pattern for sequentially indicating multiple different transmission characteristics as time passes based on the read modulation mode.

[0044] In order to generate a time-varying pattern, the modulation signal generation unit 3 determines the modulation method for the dynamic electromagnetic wave filter 5 after considering various factors.

[0045] Specifically, the modulation method determined by the modulation signal generation unit 3 is determined based on various conditions such as the modulation mode of the dynamic electromagnetic wave filter 5, the modulation period in the case of periodic modulation, the duration of continuous modulation, and the distribution of the modulation method at each position in the dynamic electromagnetic wave filter 5. The modulation mode stored in the storage unit 2 is read out, that is, at least one of the modulation modes 1 to 5.

[0046] In addition, factors in the modulation method determined by the modulation signal generation unit 3 include the frequency and level of the electromagnetic waves emitted from the device 200, the screen display characteristics of the monitor in the device 200, whether the monitor is moving, the duration of continuous setting of the monitor, the number of monitors, the electromagnetic environment around the structure 400, and in particular the presence and level of background noise of the electromagnetic waves emitted from the periphery of the device 200.

[0047] As an example of a factor, the electromagnetic environment surrounding structure 400 is shown. For example, when there is relatively high level background noise in the vicinity, the modulation mode read from storage unit 2 by modulation signal generation unit 3 is set to "Example 1 of the value of modulation mode 2" described later.

[0048] The modulation signal generation unit 3 generates a time variation pattern based on "numerical example 1 of modulation mode 2", and controls the transmission phase of the dynamic electromagnetic wave filter 5 by using a modulation signal based on the time variation pattern.

[0049] In this case, the leakage electromagnetic waves from the dynamic electromagnetic wave filter 5 incident on the electromagnetic waves emitted from the device 200 are converted into the frequency of the background noise around the structure 400.

[0050] As a result, the leaked electromagnetic waves received by the eavesdropper are superimposed with a relatively high level of background noise, thus the eavesdropper's reconstructed image becomes an unclear image containing more noise.

[0051] Alternatively, when the ambient background noise level is relatively low, the modulation mode read from the storage unit 2 by the modulation signal generation unit 3 is set to "Numerical Example 2 of Modulation Mode 2" as described later.

[0052] The modulation signal generation unit 3 generates a time variation pattern based on "numerical example 2 of modulation mode 2", and controls the transmission phase of the dynamic electromagnetic wave filter 5 by using a modulation signal based on the time variation pattern.

[0053] In this case, the dynamic electromagnetic wave filter 5 diffuses and emits the frequency of the electromagnetic waves emitted from the device 200.

[0054] The electromagnetic wave levels at each frequency after the frequency diffusion of the dynamic electromagnetic wave filter 5 are reduced relative to the electromagnetic wave level emitted from device 200 in the leakage electromagnetic wave.

[0055] As a result, the background noise level is increased relative to the level of the leaked electromagnetic waves received by the eavesdropper, and therefore, the eavesdropper's reconstructed image becomes an unclear image containing more noise.

[0056] Modulation signal generation unit 3 is implemented Figure 3 The actions shown.

[0057] That is, in step ST1, the filter frequencies of the first dynamic electromagnetic wave filter 5a to the third dynamic electromagnetic wave filter 5c, which are for the frequency of the electromagnetic waves emitted from the device 200, are determined.

[0058] In step ST2, after considering various factors, the modulation methods for the first dynamic electromagnetic wave filter 5a to the third dynamic electromagnetic wave filter 5c are determined respectively.

[0059] In step ST3, a time variation pattern representing the determined filter frequency and modulation method is generated.

[0060] The control signal output unit 4 outputs a frequency setting signal generated by the modulation signal generation unit 3, which sets the filter frequency for the electromagnetic waves emitted from the device 200, and a modulation signal based on a time variation pattern generated by the modulation signal generation unit 3 to the first dynamic electromagnetic wave filter 5a to the third dynamic electromagnetic wave filter 5c.

[0061] The modulation signal from the control signal output unit 4 is a signal generated by the modulation signal generation unit 3 to sequentially indicate multiple different transmission characteristics as time passes. For example, it is a signal for applying a bias voltage to control the active element incorporated into the dynamic electromagnetic wave filter 5, or a signal for mechanically changing the filter shape in the dynamic electromagnetic wave filter 5.

[0062] The filter frequency is set to the frequency of the electromagnetic waves emitted from device 200.

[0063] In addition, the filter frequency does not only mean the determined frequency, but also includes the frequency band.

[0064] Furthermore, the filter frequency for the electromagnetic waves emitted by the device may not be generated by the modulation signal generation unit 3, and the control signal output unit 4 may directly set the frequency of the electromagnetic waves emitted by the device 200 detected by the electromagnetic wave detection unit 1 or the frequency of the electromagnetic waves emitted by the device 200 stored in the storage unit 2 as the frequency setting signal.

[0065] The modulation signal generation unit 3 and the control signal output unit 4 are described as different structural elements, but the control unit can also be composed of these two.

[0066] In this case, the control unit receives the frequency of the electromagnetic wave emitted from the device 200 detected by the electromagnetic wave detection unit 1 or the frequency of the electromagnetic wave emitted from the device 200 stored in the storage unit 2, and outputs a frequency setting signal to set the filter frequency for the electromagnetic wave emitted from the device 200. It also reads out the modulation mode stored in the storage unit 2 and outputs a modulation signal based on a time-varying mode according to the read modulation mode. The time-varying mode is used to sequentially indicate multiple different transmission characteristics as time passes.

[0067] In order to realize a time-varying pattern that sequentially indicates multiple different transmission characteristics as time passes, the control unit outputs a modulation signal for operating the dynamic electromagnetic wave filter 5. For example, it outputs a modulation signal for applying a bias voltage to control the active elements incorporated into the dynamic electromagnetic wave filter 5, or it outputs a modulation signal for mechanically changing the filter shape in the dynamic electromagnetic wave filter 5.

[0068] Figure 2The modulation signal generation unit 3, control signal output unit 4, and storage unit 2, represented by function blocks, are constructed from a general-purpose PC (Personal Computer) or microcomputer, consisting of a CPU, RAM, and ROM. The executable program stored in the ROM, which will become the storage medium of storage unit 2, is loaded into the RAM. The CPU then performs various processes based on the loaded executable program. The ROM also functions as the recording medium of storage unit 2, storing various modulation schemes. The CPU is driven by a general-purpose operating system.

[0069] The first dynamic electromagnetic wave filter 5a to the third dynamic electromagnetic wave filter 5c are arranged side by side. The first dynamic electromagnetic wave filter 5a to the third dynamic electromagnetic wave filter 5c can also be connected sequentially to form a single structure.

[0070] The dynamic electromagnetic wave filter 5 has its filter frequency set by a frequency setting signal from the control signal output unit 4, and its transmission characteristics, which vary with time, are set by a modulation signal from the control signal output unit 4. The dynamic electromagnetic wave filter 5 transmits frequencies other than the filter frequency set by the frequency setting signal, exhibiting transmission characteristics that vary with time, as set by the modulation signal, for the filter frequency set by the frequency setting signal. Transmission characteristics refer to transmission amplitude and transmission phase.

[0071] As a result, the dynamic electromagnetic wave filter 5 attenuates or suppresses the components of the filter frequency set according to the electromagnetic wave emitted from the device 200, and modulates the electromagnetic wave emitted from the device 200, thereby emitting a leakage electromagnetic wave as a higher harmonic component obtained by adding the modulation frequency to the frequency of the electromagnetic wave emitted from the device 200.

[0072] In summary, the dynamic electromagnetic wave filter 5 attenuates not only electromagnetic waves that are components of the set filter frequency, but also electromagnetic waves of all frequency components generated by modulation.

[0073] The dynamic electromagnetic wave filter 5, for example, is composed of a frequency selective surface (FSS) and is a filter for electromagnetic waves with a two-dimensional surface. It has the following functions: it can achieve arbitrary dielectric constant / permeability for the wavelength of the incident electromagnetic wave at a set filter frequency, and it can dynamically control the amount of phase change (transmission phase) and the amount of electromagnetic wave attenuation (transmission amplitude), i.e., transmission characteristics.

[0074] The transmission characteristics are controlled by generally known methods, such as controlling the active elements incorporated into the dynamic electromagnetic wave filter 5 using electrical signals or controlling the filter shape by mechanical driving.

[0075] On the other hand, the dynamic electromagnetic wave filter 5 transmits light and frequencies other than the filter frequency. Therefore, even if the information leakage prevention shielding device 100 is installed in the window, the inside and outside of the structure 400 can be visually confirmed, and wireless communication between the inside and outside of the structure 400 can be carried out.

[0076] The dynamic electromagnetic wave filter 5 has multiple units configured in a matrix shape with multiple rows and columns.

[0077] Alternatively, all units can be set to the same filter frequency by a frequency setting signal from the control signal output unit 4, and their transmission characteristics can be controlled to be the same by a modulation signal from the control signal output unit 4.

[0078] Alternatively, multiple units may be independently set to different filter frequencies by a frequency setting signal from the control signal output unit 4, and their transmission characteristics may be controlled by a modulation signal from the control signal output unit 4.

[0079] In this case, multiple units can be divided into multiple groups, and each group can be set as a dynamic electromagnetic wave filter section with multiple units. For each dynamic electromagnetic wave filter section, the frequency can be set to a different filter frequency independently by the frequency setting signal from the control signal output section 4, and the transmission characteristics can be controlled to be different by the modulation signal from the control signal output section 4.

[0080] Next, the operation of the information leakage prevention shielding device 100 will be explained.

[0081] When electromagnetic waves containing image information are emitted from device 200, such as Figure 3 As shown in step ST1, the modulation signal generation unit 3 receives the frequency of the electromagnetic wave emitted from the device 200 or the frequency of the electromagnetic wave emitted from the device 200 stored in the storage unit 2, and determines the filter frequency of the first dynamic electromagnetic wave filter 5a to the third dynamic electromagnetic wave filter 5c.

[0082] The modulation signal generation unit 3 determines the frequency fE1 (Hz) of the electromagnetic wave emitted from the device 200 as the filter frequency for the first dynamic electromagnetic wave filter 5a, determines the frequency fE2 (Hz) of the electromagnetic wave emitted from the device 200 as the filter frequency for the second dynamic electromagnetic wave filter 5b, and determines the frequency fE3 (Hz) of the electromagnetic wave emitted from the device 200 as the filter frequency for the third dynamic electromagnetic wave filter 5c.

[0083] Next, as Figure 3 As shown in step ST2, the modulation signal generation unit 3 selects a modulation method from the modulation method 1 to modulation method 5 stored in the storage unit 2 according to various factors, and determines the modulation method according to various conditions.

[0084] After determining the modulation method, the modulation signal generation unit 3, such as Figure 3 As shown in step ST3, a time-varying pattern representing the determined filter frequency and modulation method is generated.

[0085] The control signal output unit 4 outputs a frequency setting signal that sets the filter frequency of the electromagnetic waves emitted from the device 200, generated by the modulation signal generation unit 3, and a modulation signal based on the time variation pattern generated by the modulation signal generation unit 3 to the first dynamic electromagnetic wave filter 5a to the third dynamic electromagnetic wave filter 5c.

[0086] The first dynamic electromagnetic wave filter 5a to the third dynamic electromagnetic wave filter 5c are each set to a filter frequency by a frequency setting signal from the control signal output unit 4, and are controlled by a modulation signal from the control signal output unit 4 to achieve different transmission characteristics over time.

[0087] That is, the first dynamic electromagnetic wave filter 5a to the third dynamic electromagnetic wave filter 5c attenuate or suppress the frequencies fE1 (Hz), fE2 (Hz), and fE3 (Hz) of the electromagnetic waves emitted from the device 200, respectively, and emit leakage electromagnetic waves after the frequencies fE1 (Hz), fE2 (Hz), and fE3 (Hz) are modulated based on the time-varying mode.

[0088] In the information leakage prevention shielding device 100 of Embodiment 1, the dynamic electromagnetic wave filter 5 attenuates or suppresses the frequency of the electromagnetic waves emitted from the device 200 and emits leakage electromagnetic waves after the frequency of the electromagnetic waves emitted from the device 200 is modulated based on the time variation pattern. Therefore, by eavesdropping on the electromagnetic waves emitted from the device 200, the accumulation of image data required for averaging can be interfered with, and the possibility of information being stolen from the electromagnetic waves emitted from the device 200 can be reduced.

[0089] Next, the dynamic electromagnetic wave filter 5 will be controlled by modulation mode 1 to modulation mode 5 according to each modulation mode.

[0090] <Modulation Method 1>

[0091] A modulation method for modulating electromagnetic waves by randomly switching the transmission characteristics mode of the dynamic electromagnetic wave filter 5 over time.

[0092] Based on the electromagnetic waves emitted from the device 200 detected by the electromagnetic wave detection unit 1, when the screen display characteristics of the monitor in the device 200, which is a factor in determining the modulation method, are determined to be frequently changing, the modulation mode 1 stored in the storage unit 2 is read out, and a time variation pattern for indicating multiple different transmission phases is generated by randomly switching the transmission characteristics over time using the modulation mode 1.

[0093] The transmission characteristics that switch randomly over time are mainly the transmission phase, but the transmission amplitude can also be changed at the same time.

[0094] The control signal output unit 4 outputs the modulation signal based on the time variation mode of modulation method 1 to the first dynamic electromagnetic wave filter 5a to the third dynamic electromagnetic wave filter 5c.

[0095] The first dynamic electromagnetic wave filter 5a is set to fE1 (Hz) as the filter frequency by the frequency setting signal from the control signal output unit 4. For the electromagnetic waves emitted from the device 200, the frequency fE1 (Hz) is randomly changed over time by the modulation signal from the control signal output unit 4, and is emitted as a randomly changed leakage electromagnetic wave.

[0096] The second dynamic electromagnetic wave filter 5b is set to fE2 (Hz) as the filter frequency by the frequency setting signal from the control signal output unit 4. For the electromagnetic waves emitted from the device 200, the frequency fE2 (Hz) is randomly changed over time by the modulation signal from the control signal output unit 4, and is emitted as a randomly changed leakage electromagnetic wave.

[0097] The third dynamic electromagnetic wave filter 5c is set to fE3 (Hz) as the filter frequency by the frequency setting signal from the control signal output unit 4. For the electromagnetic waves emitted from the device 200, the frequency fE3 (Hz) is randomly changed over time by the modulation signal from the control signal output unit 4, and is emitted as a randomly changed leakage electromagnetic wave.

[0098] By means of modulation 1, the waveform of the leakage electromagnetic wave from the dynamic electromagnetic wave filter 5, which is incident on the electromagnetic wave containing image information emitted from the device 200, is randomly modulated, and the waveform of the electromagnetic wave containing image information emitted from the device 200 is changed.

[0099] By randomly altering the waveform of the leaked electromagnetic waves, it is possible to prevent eavesdroppers from accurately reproducing image information.

[0100] <Modulation Method 2>

[0101] This is a modulation method that modulates electromagnetic waves by repeatedly switching the transmission characteristics of the dynamic electromagnetic wave filter 5 in a time-periodic manner.

[0102] The transmission characteristics that change periodically over time are mainly the transmission phase, but the transmission amplitude can also be changed at the same time.

[0103] Modulation method 2 is used to modulate the leaked electromagnetic wave containing image information as follows.

[0104] The waveform of the leakage electromagnetic wave under the condition of repeated modulation in a periodic mode is obtained as follows. Let the period of the periodic modulation mode be Tm (s), and the modulation frequency be fm = 1 / Tm (Hz).

[0105] At this time, the complex transmission coefficient T(t) of the dynamic electromagnetic wave filter 5 is represented by the complex Fourier series shown in equation (1).

[0106]

[0107] The coefficient of the nth degree of the series can be calculated by the following formula (2).

[0108]

[0109] Therefore, the complex electric field Et(t) of the leakage electromagnetic wave when the electromagnetic wave of frequency f (Hz) is incident on the dynamic electromagnetic wave filter 5 is represented by the following equation (3).

[0110]

[0111] Therefore, it can be seen that through periodic modulation, the leaked electromagnetic wave has higher harmonic components of f+n·fm in addition to the components at frequency f (Hz).

[0112] Furthermore, the frequency of the higher harmonics containing the higher harmonic components mentioned here is not a frequency equivalent to an integer multiple of the higher harmonics of the electromagnetic waves emitted from the device 200, but rather a frequency obtained by adding an integer multiple of the modulation frequency to the frequency of the electromagnetic waves emitted from the device 200.

[0113] The following shows a numerical example of modulation mode 2 and its effect.

[0114] Furthermore, the following numerical example illustrates a periodic modulation method and its effects, and any modulation method based on combinations of other periodic values ​​can be used. In any case, it is possible to interfere with the eavesdropper's tuning of the receiving frequency of the eavesdropping device to the frequency of the leaking electromagnetic wave, the reconstruction of the image after reception, and the accumulation of the reconstructed image and improvement of image clarity through averaging.

[0115] Numerical Example 1 for Modulation Mode 2

[0116] As the first dynamic electromagnetic wave filter 5a to the third dynamic electromagnetic wave filter 5c, the transmission amplitude is set to a fixed value of -50dB. Following the approach of modulation method 2, such as... Figure 4 As shown, modulation is performed to increase the transmission phase to 2π in 10 stages at 2π / 10 (rad) increments.

[0117] At this point, the numerical example 1 of modulation mode 2 becomes a periodic mode with period Tm(s).

[0118] exist Figure 4 In the diagram, the horizontal axis represents time, and the vertical axis represents the transmission phase.

[0119] In addition, to avoid complicated explanations, the transmission amplitude is set to a fixed value of -50dB. However, it does not have to be a fixed value like -50dB. It can also be changed to -45dB and -55dB for each cycle.

[0120] When the modulation signal generation unit 3 determines that a relatively high level of background noise exists in the electromagnetic environment around the device 200 detected by the electromagnetic wave detection unit 1, which is a factor in determining the modulation method, the modulation signal generation unit 3 reads out the numerical example 1 of the modulation method 2 stored in the storage unit 2 and generates a time variation pattern that sequentially indicates multiple different transmission phases as time passes. This time variation pattern is achieved by repeatedly modulating the numerical example 1 of the modulation method 2, that is, increasing the transmission phase to 2π in 10 stages every 2π / 10 (rad) in the period Tm (s).

[0121] The control signal output unit 4 outputs the modulation signal based on the time variation mode of the numerical example 1 of modulation method 2 to the first dynamic electromagnetic wave filter 5a to the third dynamic electromagnetic wave filter 5c.

[0122] The dynamic electromagnetic wave filter 5, which receives the modulation signal from the control signal output unit 4, emits a leakage electromagnetic wave with an amplitude calculated by the above formula (3).

[0123] Figure 5 The calculation results of the amplitude of the leaked electromagnetic wave up to the frequency of the ±5th higher harmonic component from the dynamic electromagnetic wave filter 5 are shown.

[0124] exist Figure 5 In the diagram, the horizontal axis represents the order of higher harmonics, the vertical axis represents the amplitude of the leaked electromagnetic wave, the 0 symbol indicates the case of numerical example 1 where modulation mode 2 is implemented, and the × symbol indicates the case where no modulation is performed, that is, a comparative example where the transmission amplitude is set to a fixed value of -50dB and the transmission phase is not changed, i.e., a fixed value is set without modulation.

[0125] In the comparative example, only the 0th harmonic is present, which is the component with the same frequency f (Hz) as the incident wave.

[0126] In contrast, when the dynamic electromagnetic wave filter 5 is modulated by modulation method 2 (numerical example 1), the leakage electromagnetic wave from the dynamic electromagnetic wave filter 5 has a first-order harmonic, that is, a high-order harmonic component with frequency f+fm (Hz), and the component with frequency f (Hz) is suppressed.

[0127] Furthermore, in both modulation mode 2 and the comparative example, the transmission amplitude (amplitude of the leaked electromagnetic wave) is approximately -50 dB.

[0128] Therefore, the first dynamic electromagnetic wave filter 5a is set to fE1 (Hz) as the filter frequency by the frequency setting signal from the control signal output unit 4. For the electromagnetic waves emitted from the device 200, it suppresses the component of frequency fE1 (Hz) and emits leakage electromagnetic waves composed of the first higher harmonic component of frequency fE1+fm1 (Hz).

[0129] The second dynamic electromagnetic wave filter 5b is set to fE2 (Hz) as the filter frequency by the frequency setting signal from the control signal output unit 4. For electromagnetic waves emitted from the device 200, it suppresses the component of frequency fE2 (Hz) and emits leakage electromagnetic waves composed of the first higher harmonic component of frequency fE2 + fm2 (Hz).

[0130] The third dynamic electromagnetic wave filter 5c is set to fE3 (Hz) as the filter frequency by the frequency setting signal from the control signal output unit 4. For electromagnetic waves emitted from the device 200, it suppresses the component of frequency fE3 (Hz) and emits leakage electromagnetic waves composed of the first higher harmonic component of frequency fE3+fm3 (Hz).

[0131] In this way, by performing modulation in modulation mode 2 (numerical example 1), the leakage electromagnetic wave emitted from the dynamic electromagnetic wave filter 5 consists only of the first harmonic component with frequency f+fm (Hz), and the leakage electromagnetic wave emitted from the dynamic electromagnetic wave filter 5 can deceive the electromagnetic wave emitted from the device 200.

[0132] Therefore, by switching the control of the dynamic electromagnetic wave filter 5 based on modulation mode 2 (numerical example 1) and the control that prevents the dynamic electromagnetic wave filter 5 from operating, only one of the frequency f+fm (Hz) of the leakage electromagnetic wave from the dynamic electromagnetic wave filter 5 and the frequency f (Hz) of the electromagnetic wave emitted from the device 200 exists in time. Therefore, the eavesdropper cannot stably tune to the frequency of the electromagnetic wave emitted from the device 200.

[0133] The result is that the accumulation of image data required for averaging can be disrupted.

[0134] Furthermore, by varying the period Tm(s) in a timely manner instead of keeping it fixed, the frequency f+fm(Hz) can be varied, which can interfere with the accumulation of image data required for averaging.

[0135] Numerical Example 2 for Modulation Mode 2

[0136] As the first dynamic electromagnetic wave filter 5a to the third dynamic electromagnetic wave filter 5c, the transmission amplitude is set to a fixed value of -50dB. Following the approach of modulation method 2, the transmission phase is set to 2.5sin(α(t))(rad). Figure 4 As shown, modulation is performed to increase α(t) to 2π in 10 stages at 2π / 10 (rad) increments.

[0137] At this point, the numerical example 2 of modulation method 2 becomes a periodic modulation mode in time.

[0138] In addition, to avoid complicated explanations, the transmission amplitude is set to a fixed value of -50dB. However, it does not have to be a fixed value like -50dB. It can also be changed to -45dB and -55dB for each cycle.

[0139] When the modulation signal generation unit 3 determines that the electromagnetic environment around the structure 400 detected by the electromagnetic wave detection unit 1 is a relatively low level of background noise, which is a factor in determining the modulation method, the modulation signal generation unit 3 reads the numerical example 2 of the modulation method 2 stored in the storage unit 2 and generates a time variation pattern that sequentially indicates multiple different transmission phases as time passes. This time variation pattern is achieved by repeatedly modulating the numerical example 2 of the modulation method 2, that is, setting the transmission phase to 2.5sin(α(t))(rad) and increasing α(t) to 2π in 10 stages at 2π / 10(rad).

[0140] The control signal output unit 4 outputs the modulation signal based on the time variation mode of the numerical example 2 of modulation method 2 to the first dynamic electromagnetic wave filter 5a to the third dynamic electromagnetic wave filter 5c.

[0141] The dynamic electromagnetic wave filter 5, which receives the modulation signal from the control signal output unit 4, emits a leakage electromagnetic wave with an amplitude calculated by the above formula (3).

[0142] Figure 6 The calculation results of the amplitude of the leaked electromagnetic wave up to the frequency of the ±5th higher harmonic component from the dynamic electromagnetic wave filter 5 are shown.

[0143] exist Figure 6In the diagram, the horizontal axis represents the order of higher harmonics, the vertical axis represents the amplitude of the leaked electromagnetic wave, the 〇 symbol indicates the case of numerical example 2 with modulation mode 2 implemented, and the × symbol indicates the comparative case without modulation.

[0144] When the dynamic electromagnetic wave filter 5 is modulated using modulation method 2 (numerical example 2), the frequency f (Hz) in the leakage electromagnetic wave from the dynamic electromagnetic wave filter 5, which is the same as the incident wave, is suppressed by about -25dB. The nth harmonic component with frequency f+n·fm (Hz) in the leakage electromagnetic wave from the dynamic electromagnetic wave filter 5 is suppressed by more than several dB.

[0145] Therefore, the first dynamic electromagnetic wave filter 5a is set to fE1 (Hz) as the filter frequency by the frequency setting signal from the control signal output unit 4. For electromagnetic waves emitted from the device 200, the component with frequency fE1 (Hz) is suppressed by about -25dB, and the nth higher harmonic component with frequency fE1+n·fm1 (Hz) is suppressed by more than several dB.

[0146] The second dynamic electromagnetic wave filter 5b is set to fE2 (Hz) as the filter frequency by the frequency setting signal from the control signal output unit 4. For electromagnetic waves emitted from the device 200, the component with the emission frequency fE2 (Hz) is suppressed by about -25dB, and the nth higher harmonic component with the frequency fE2+n·fm2 (Hz) is suppressed by more than several dB.

[0147] The third dynamic electromagnetic wave filter 5c is set to fE3 (Hz) as the filter frequency by the frequency setting signal from the control signal output unit 4. For electromagnetic waves emitted from the device 200, the component with the emission frequency fE3 (Hz) is suppressed by about -25dB, and the nth higher harmonic component with the frequency fE3+n·fm3 (Hz) is suppressed by more than several dB.

[0148] In this way, by performing modulation in modulation mode 2 (numerical example 2), the frequency f (Hz) of the same frequency as the incident wave in the leakage electromagnetic wave can be reduced, and the frequency f+n·fm (Hz) of each higher harmonic component emitted can be used as the leakage electromagnetic wave.

[0149] Therefore, by performing modulation in modulation method 2 (numerical example 2), the relative amount of background noise with respect to the leakage electromagnetic wave from the dynamic electromagnetic wave filter 5 increases. Thus, when the eavesdropper tunes to any frequency, there is an effect of reducing the clarity of the reproduced image.

[0150] The result is that the accumulation of image data required for averaging can be disrupted.

[0151] Furthermore, by switching the presence or absence of modulation mode 2 (numerical example 2), or by making the period Tm(s) in modulation mode 2 (numerical example 2) change in a timely manner instead of being fixed, the frequency f(Hz) and frequency f+n·fm(Hz) of the leakage electromagnetic wave can be changed, thereby interfering with the accumulation of image data required for averaging.

[0152] Numerical Example 3 for Modulation Mode 2

[0153] As the first dynamic electromagnetic wave filter 5a to the third dynamic electromagnetic wave filter 5c, the transmission amplitude is set to a fixed value of -50dB. According to the idea of ​​modulation method 2, the transmission phase is modulated by switching between the two values ​​of 0 (rad) and π (rad) every period Tm / 2 (s).

[0154] At this point, the numerical example 3 of modulation method 2 becomes a periodic mode with period Tm(s).

[0155] In addition, to avoid complicated explanations, the transmission amplitude is set to a fixed value of -50dB. However, it does not have to be a fixed value like -50dB. It can also be changed to -45dB and -55dB for each cycle.

[0156] When the modulation signal generation unit 3 determines that the electromagnetic environment around the structure 400 detected by the electromagnetic wave detection unit 1 is low-level background noise, which is a factor in determining the modulation method, it reads the numerical example 3 of the modulation mode 2 stored in the storage unit 2 and generates a time variation pattern that sequentially indicates multiple different transmission phases as time passes. This time variation pattern is achieved by the numerical example 3 of the modulation mode 2, which is the mode that switches the transmission phase to the values ​​of 0 (rad) and π (rad) according to each period Tm / 2 (s).

[0157] The control signal output unit 4 outputs the modulation signal based on the time variation mode of the numerical example 3 of modulation method 2 to the first dynamic electromagnetic wave filter 5a to the third dynamic electromagnetic wave filter 5c.

[0158] The dynamic electromagnetic wave filter 5, which receives the modulation signal from the control signal output unit 4, emits a leakage electromagnetic wave with an amplitude calculated by the above formula (3).

[0159] Figure 7 The calculation results of the amplitude of the leaked electromagnetic wave up to the frequency of the ±5th higher harmonic component from the dynamic electromagnetic wave filter 5 are shown.

[0160] exist Figure 7 In the diagram, the horizontal axis represents the order of higher harmonics, the vertical axis represents the amplitude of the leaked electromagnetic wave, the 〇 symbol indicates the case of numerical example 3 where modulation mode 2 was implemented, and the × symbol indicates the comparative case where no modulation was performed.

[0161] When the dynamic electromagnetic wave filter 5 is modulated by modulation method 2 (numerical example 3), in the leakage electromagnetic wave from the dynamic electromagnetic wave filter 5, the high-order harmonic components with the same frequency f (Hz) as the incident wave and even-order frequencies f+n·fm (Hz) (where n is even) are suppressed, and the high-order harmonic components with odd-order frequencies f+n·fm (Hz) (where n is odd) are suppressed by more than dB.

[0162] Therefore, the first dynamic electromagnetic wave filter 5a is set to fE1 (Hz) as the filter frequency by the frequency setting signal from the control signal output unit 4. For electromagnetic waves emitted from the device 200, it suppresses components with frequency fE1 (Hz) and even-order high-order harmonic components with frequency fE1+n·fm1 (Hz) (where n is even), and emits leakage electromagnetic waves with odd-order high-order harmonic components with frequency fE1+n·fm1 (Hz) (where n is odd) suppressed by more than a few dB.

[0163] The second dynamic electromagnetic wave filter 5b is set to fE2 (Hz) as the filter frequency by the frequency setting signal from the control signal output unit 4. For electromagnetic waves emitted from the device 200, it suppresses components with frequency fE2 (Hz) and even-order high-order harmonic components with frequency fE2+n·fm2 (Hz) (where n is even). It emits leakage electromagnetic waves with odd-order high-order harmonic components with frequency fE2+n·fm2 (Hz) (where n is odd) that are suppressed by more than a few dB.

[0164] The third dynamic electromagnetic wave filter 5c is set to fE3 (Hz) as the filter frequency by the frequency setting signal from the control signal output unit 4. For electromagnetic waves emitted from the device 200, it suppresses components with frequency fE3 (Hz) and even-order high-order harmonic components with frequency fE3+n·fm3 (Hz) (where n is even). It emits leakage electromagnetic waves with odd-order high-order harmonic components with frequency fE3+n·fm3 (Hz) (where n is odd) that are suppressed by more than several dB.

[0165] Thus, by performing modulation in modulation mode 2 (numerical example 3), the frequency f (Hz) and even-numbered frequencies f+n·fm (Hz) (where n is even) of the leakage electromagnetic wave from the dynamic electromagnetic wave filter 5 are not present, and the frequency f+n·fm (Hz) (where n is odd) is emitted.

[0166] Therefore, by performing modulation in modulation mode 2 (numerical example 3), it is difficult for the eavesdropper to determine the frequency of the leaked electromagnetic wave.

[0167] As a result, it is possible to interfere with the frequency tuning of the leaked electromagnetic waves, and also to interfere with the accumulation of image data required for averaging.

[0168] <Modulation Method 3>

[0169] The modulation method in which multiple dynamic electromagnetic wave filters 5 are modulated in a shielding device 100 for preventing information leakage by means of multiple dynamic electromagnetic wave filters 5.

[0170] Multiple dynamic electromagnetic wave filters 5 are set to different filter frequencies and modulated by either modulation method 1 or modulation method 2. The modulation method is a modulation method that makes the frequencies of the modulated higher harmonic components equal to each other.

[0171] The modulation signal generation unit 3 determines different filter frequencies for the first dynamic electromagnetic wave filter 5a to the third dynamic electromagnetic wave filter 5c, makes a judgment based on the factors that determine the modulation method, and reads the numerical value of modulation mode 2, for example, Example 1, from the storage unit 2 to generate a time variation pattern.

[0172] The control signal output unit 4 outputs the frequency setting signal for setting the filter frequency and the modulation signal for the time variation mode based on the numerical example 1 of modulation method 2 to the first dynamic electromagnetic wave filter 5a to the third dynamic electromagnetic wave filter 5c.

[0173] The first dynamic electromagnetic wave filter 5a sets the frequency fE1 (Hz) of the electromagnetic wave emitted from the device 200 as the filter frequency. As shown in the numerical example 1 of modulation mode 2, for the electromagnetic wave emitted from the device 200, the component of frequency fE1 (Hz) is suppressed, and the leakage electromagnetic wave composed of the first higher harmonic component of frequency fE1+fm1 (Hz) obtained by adding the modulation frequency fm1 (Hz) to the filter frequency fE1 (Hz) is emitted.

[0174] The second dynamic electromagnetic wave filter 5b sets the frequency fE2 (Hz) of the electromagnetic wave emitted from the device 200 as the filter frequency. As shown in the numerical example 1 of modulation mode 2, for the electromagnetic wave emitted from the device 200, the component of frequency fE2 (Hz) is suppressed, and the leakage electromagnetic wave composed of the first higher harmonic component of frequency fE2+fm2 (Hz) obtained by adding the modulation frequency fm2 (Hz) to the filter frequency fE2 (Hz) is emitted.

[0175] The third dynamic electromagnetic wave filter 5c sets the frequency fE3 (Hz) of the electromagnetic wave emitted from the device 200 as the filter frequency. As shown in the numerical example 1 of modulation mode 2, for the electromagnetic wave emitted from the device 200, the component of frequency fE3 (Hz) is suppressed, and the leakage electromagnetic wave composed of the first higher harmonic component of frequency fE3+fm3 (Hz) obtained by adding the modulation frequency fm3 (Hz) to the filter frequency fE3 (Hz) is emitted.

[0176] Here, the modulation frequency fm1 (Hz) of the first dynamic electromagnetic wave filter 5a, the modulation frequency fm2 (Hz) of the second dynamic electromagnetic wave filter 5b, and the modulation frequency fE3 (Hz) of the third dynamic electromagnetic wave filter 5c are set to be the same, so that the frequencies fE1+fm1 (Hz) of the modulated leakage electromagnetic wave from the first dynamic electromagnetic wave filter 5a, fE2+fm2 (Hz) of the modulated leakage electromagnetic wave from the second dynamic electromagnetic wave filter 5b, and fE3+fm3 (Hz) of the modulated leakage electromagnetic wave from the third dynamic electromagnetic wave filter 5c are set to be the same.

[0177] Thus, by performing modulation method 3, the frequencies of the leakage electromagnetic waves from the first dynamic electromagnetic wave filter 5a to the third dynamic electromagnetic wave filter 5c are the same. Therefore, for the frequencies fE1 (Hz) to fE3 (Hz) of the three electromagnetic waves, there is only one frequency of the modulated leakage electromagnetic wave.

[0178] Therefore, by modulating in modulation mode 3, it is difficult for the eavesdropper to determine the frequency of the leaked electromagnetic wave.

[0179] As a result, it is possible to interfere with the frequency tuning of the leaked electromagnetic waves, and also to interfere with the accumulation of image data required for averaging.

[0180] In addition, the number of dynamic electromagnetic wave filters 5 is not limited to 3; it can be 2 or 4 or more, as long as there are multiple filters.

[0181] <Modulation Method 4>

[0182] The modulation method 4 is as follows: In the dynamic electromagnetic wave filter 5 with multiple units, the multiple units are divided into multiple groups, and each group is set as a dynamic electromagnetic wave filter section with multiple units. The multiple dynamic electromagnetic wave filter sections are modulated by different modulation methods.

[0183] That is, it is a modulation method that makes the modulation method different depending on the position on the dynamic electromagnetic wave filter 5.

[0184] As an example, for the multiple dynamic electromagnetic wave filter sections in the dynamic electromagnetic wave filter 5, the numerical example 1 of modulation method 2 is used for modulation, so that the period Tm(s) of the modulation mode for the multiple dynamic electromagnetic wave filter sections in the dynamic electromagnetic wave filter 5 are different respectively.

[0185] That is, the modulation signal generation unit 3 makes a judgment based on the factors that determine the modulation method. For example, it reads the numerical value of the modulation mode 2 from the storage unit 2, and generates a time variation pattern with different period Tm(s) of the modulation mode for multiple dynamic electromagnetic wave filter units in the dynamic electromagnetic wave filter 5.

[0186] The operation of the multiple dynamic electromagnetic wave filter sections in the dynamic electromagnetic wave filter 5 is the same as that described in the numerical example 1 of modulation mode 2, so the description is omitted.

[0187] Thus, by performing modulation mode 4, which varies depending on the position of the dynamic electromagnetic wave filter 5, the frequency of the leaked electromagnetic wave varies depending on the location where the leaked electromagnetic wave from the dynamic electromagnetic wave filter 5 is received.

[0188] Therefore, by using modulation method 4, the frequency of the leakage wave is difficult to tune, which is achieved by modulation method 2 (numerical example 1). Even if the eavesdropper moves around while trying to eavesdrop, or sets up multiple eavesdropping devices in different locations to try to eavesdrop, the frequency of the leakage electromagnetic wave will vary depending on the location of reception. Therefore, it is necessary to repeatedly tune according to each movement or according to each eavesdropping device.

[0189] The result is that the accumulation of image data required for averaging can be disrupted.

[0190]

[0191] A variation of modulation method 4 is as follows: In a dynamic electromagnetic wave filter 5 having multiple units, the multiple units are divided into multiple groups, and each group is set as a dynamic electromagnetic wave filter section having multiple units. For each of the multiple dynamic electromagnetic wave filter sections, a beam scanning technique known as a phased array is applied.

[0192] That is, the modulation method is as follows: for the dynamic electromagnetic wave filter section, the modulation timing is modulated with an appropriate time offset, thereby controlling the emission direction of the leakage electromagnetic wave, or setting the timing so that the leakage electromagnetic wave does not radiate in a specific direction at all.

[0193] The modulation signal generation unit 3 generates a time variation pattern based on a beam scanning technique known as a phased array, which is applied to multiple dynamic electromagnetic wave filter units in the dynamic electromagnetic wave filter 5.

[0194] The control signal output unit 4 outputs a modulation signal based on a time-varying mode of modulation using beam scanning technology to multiple dynamic electromagnetic wave filter units of each of the first dynamic electromagnetic wave filter 5a to the third dynamic electromagnetic wave filter 5c.

[0195] The multiple dynamic electromagnetic wave filter sections of the dynamic electromagnetic wave filter 5 are modulated by a modulation method that applies beam scanning technology to emit leakage electromagnetic waves.

[0196] In this way, modulation is performed with a time offset according to the position on the dynamic electromagnetic wave filter 5. As a result, if the leakage electromagnetic wave cannot be received according to the location where the leakage electromagnetic wave from the dynamic electromagnetic wave filter 5 is received, the direction of receiving the leakage electromagnetic wave will be completely different.

[0197] Therefore, by performing modulation of the variation of modulation method 4, it is difficult to tune the leaked electromagnetic waves regardless of whether the eavesdropper moves or the number of locations where the eavesdropping device is set.

[0198] The result is that the accumulation of image data required for averaging can be disrupted.

[0199] <Modulation Method 5>

[0200] The modulation method 5 is as follows: it is not fixed to one of the modulation methods 1, 2 (numerical examples 1 to 3), 3, and 4 (including variant examples) shown above, but selects at least two of these multiple modulation methods and repeats them in turn to modulate the dynamic electromagnetic wave filter 5.

[0201] Thus, by using different modulation methods, the frequency of the leaked electromagnetic wave modulated by the dynamic electromagnetic wave filter 5 varies according to each modulation method.

[0202] Therefore, by using modulation mode 5, it is difficult for the eavesdropper to take countermeasures corresponding to the modulation mode each time the modulation mode is switched, and it is difficult for the eavesdropper to determine the frequency of the leaked electromagnetic wave.

[0203] As a result, it is possible to interfere with the frequency tuning of the leaked electromagnetic waves, and also to interfere with the accumulation of image data required for averaging.

[0204] Implementation Method 2

[0205] use Figure 8 The information leakage prevention shielding device 100 of Embodiment 2 will be described.

[0206] The difference between the information leakage prevention shielding device 100 of Embodiment 2 and the information leakage prevention shielding device 100 of Embodiment 1 is that a first interference wave generating device 6 is added, and the other aspects are the same as the information leakage prevention shielding device 100 of Embodiment 1.

[0207] exist Figure 8 In, with Figure 2 The same labels indicate the same or equivalent parts.

[0208] In the information leakage prevention shielding device 100 of Embodiment 2, the structure is the same as that of the information leakage prevention shielding device 100 of Embodiment 1, except for the first interference wave generating device 6. Therefore, the description is omitted and the description will focus on the first interference wave generating device 6.

[0209] The information leakage prevention shielding device 100 of Embodiment 2 intentionally superimposes the interference electromagnetic waves from the first interference wave generating device 6 into the leakage electromagnetic waves from the first dynamic electromagnetic wave filter 5a to the third dynamic electromagnetic wave filter 5c, thereby improving the information leakage prevention effect.

[0210] The first interference wave generating device 6 is a device that radiates radio waves by means of radiating elements such as antennas.

[0211] The first interference wave generating device 6 is positioned closer to the eavesdropping device 300 than the first dynamic electromagnetic wave filter 5a to the third dynamic electromagnetic wave filter 5c, specifically on the side opposite to the side where the device 200 is located.

[0212] That is, the first interference wave generating device 6 is located on the outside of the structure 400, or on the outside of the structure 400, compared to the first dynamic electromagnetic wave filter 5a to the third dynamic electromagnetic wave filter 5c.

[0213] The first interference wave generating device 6 receives the filter frequencies of the first dynamic electromagnetic wave filter 5a to the third dynamic electromagnetic wave filter 5c determined by the modulation signal generating unit 3 and the time variation pattern of the modulation method for the first dynamic electromagnetic wave filter 5a to the third dynamic electromagnetic wave filter 5c respectively, and emits an interference electromagnetic wave with a frequency equal to that of the leakage electromagnetic wave emitted from the first dynamic electromagnetic wave filter 5a to the third dynamic electromagnetic wave filter 5c.

[0214] For example, when the leakage electromagnetic waves emitted from the first dynamic electromagnetic wave filter 5a to the third dynamic electromagnetic wave filter 5c have high-order harmonic components with frequencies of fL1 (Hz) to fL10 (Hz), the frequency of the interference electromagnetic waves from the first interference wave generating device 6 is fL1 (Hz) to fL10 (Hz).

[0215] When the first dynamic electromagnetic wave filter 5a to the third dynamic electromagnetic wave filter 5c are modulated using the numerical example 1 of modulation method 2, the higher harmonic components of the leakage electromagnetic waves emitted from the first dynamic electromagnetic wave filter 5a to the third dynamic electromagnetic wave filter 5c with frequencies fL1 (Hz) to fL10 (Hz) are frequencies fE1+fm1 (Hz), fE2+fm2 (Hz), and fE3+fm3 (Hz). When modulated using the numerical example 2 of modulation method 2, the higher harmonic components of the leakage electromagnetic waves emitted from the first dynamic electromagnetic wave filter 5a to the third dynamic electromagnetic wave filter 5c with frequencies fL1 (Hz) to fL10 (Hz) are... The higher harmonic components of z) are frequencies fE1+n·fm1 (Hz), fE2+n·fm2 (Hz), and fE3+n·fm3 (Hz). When modulated by the numerical example 3 of modulation method 2, the higher harmonic components of frequencies fL1 (Hz) to fL10 (Hz) in the leakage electromagnetic waves emitted from the first dynamic electromagnetic wave filter 5a to the third dynamic electromagnetic wave filter 5c are odd-order frequencies fE1+n·fm1 (Hz) (where n is odd), odd-order frequencies fE2+n·fm2 (Hz) (where n is odd), and odd-order frequencies fE3+n·fm3 (Hz) (where n is odd).

[0216] Next, the operation of the information leakage prevention shielding device 100 will be explained.

[0217] Similar to the operation of the information leakage prevention shielding device 100 in Embodiment 1, the modulation signal generation unit 3 determines the filter frequency for the first dynamic electromagnetic wave filter 5a to the third dynamic electromagnetic wave filter 5c and generates a time variation pattern based on the selected modulation method.

[0218] The control signal output unit 4 outputs a frequency setting signal for setting the filter frequency and a modulation signal based on the selected modulation method to the first dynamic electromagnetic wave filter 5a to the third dynamic electromagnetic wave filter 5c.

[0219] The first dynamic electromagnetic wave filter 5a to the third dynamic electromagnetic wave filter 5c are set to filter frequency by a frequency setting signal. By modulating the signal, the transmission phase is switched over time, and leakage electromagnetic waves with high-order harmonic components with frequencies fL1 (Hz) to fL10 (Hz) are emitted.

[0220] On the other hand, the first interference wave generating device 6 receives the filter frequencies of the first dynamic electromagnetic wave filter 5a to the third dynamic electromagnetic wave filter 5c determined by the modulation signal generating unit 3 and the time variation patterns of the modulation methods for the first dynamic electromagnetic wave filter 5a to the third dynamic electromagnetic wave filter 5c respectively, and emits interference electromagnetic waves with frequencies fL1 (Hz) to fL10 (Hz) that are equal to the frequencies of the leakage electromagnetic waves emitted from the first dynamic electromagnetic wave filter 5a to the third dynamic electromagnetic wave filter 5c.

[0221] Therefore, interference electromagnetic waves with frequencies fL1 (Hz) to fL10 (Hz) from the first interference wave generating device 6 are superimposed on the leakage electromagnetic waves with high-order harmonic components from the first dynamic electromagnetic wave filter 5a to the third dynamic electromagnetic wave filter 5c.

[0222] Therefore, it is difficult for eavesdroppers to determine the frequency of the leaked electromagnetic waves.

[0223] As a result, it is possible to interfere with the frequency tuning of the leaked electromagnetic waves, and also to interfere with the accumulation of image data required for averaging.

[0224] Furthermore, by limiting the frequency of the radiated interference electromagnetic wave to the frequency of the leakage electromagnetic wave, not only can the power required for the radiation of the interference electromagnetic wave in the first interference wave generating device 6 be reduced to a minimum, but the possibility of the interference electromagnetic wave from the first interference wave generating device 6 causing wireless interference to other devices can also be reduced.

[0225] In addition, the first interference wave generating device 6 emits interference electromagnetic waves with frequencies that are all equal to the frequencies of the leakage electromagnetic waves emitted from the first dynamic electromagnetic wave filter 5a to the third dynamic electromagnetic wave filter 5c. However, it may also emit interference electromagnetic waves with frequencies that are equal to a portion of the frequencies of the leakage electromagnetic waves emitted from the first dynamic electromagnetic wave filter 5a to the third dynamic electromagnetic wave filter 5c.

[0226] Implementation Method 3

[0227] use Figure 9 The information leakage prevention shielding device 100 of Embodiment 3 will be described.

[0228] The difference between the information leakage prevention shielding device 100 of Embodiment 3 and the information leakage prevention shielding device 100 of Embodiment 1 is that a second interference wave generating device 7 is added, and the other aspects are the same as the information leakage prevention shielding device 100 of Embodiment 1.

[0229] exist Figure 9 In, with Figure 2 The same labels indicate the same or equivalent parts.

[0230] In the information leakage prevention shielding device 100 of Embodiment 3, the structure is the same as that of the information leakage prevention shielding device 100 of Embodiment 1, except for the second interference wave generating device 7. Therefore, the description is omitted and the description will focus on the second interference wave generating device 7.

[0231] The information leakage prevention shielding device 100 of embodiment 3 intentionally superimposes interference electromagnetic waves from the second interference wave generating device 7 into the electromagnetic waves emitted by the slave device 200 that are incident on the first dynamic electromagnetic wave filter 5a to the third dynamic electromagnetic wave filter 5c, thereby improving the information leakage prevention effect.

[0232] The second interference wave generating device 7 is a device that radiates radio waves by means of radiating elements such as antennas.

[0233] The second interference wave generating device 7 is located on the side farther away from the eavesdropping device 300 than the first dynamic electromagnetic wave filter 5a to the third dynamic electromagnetic wave filter 5c, and on the side closer to the device 200 than the first dynamic electromagnetic wave filter 5a to the third dynamic electromagnetic wave filter 5c.

[0234] That is, the second interference wave generating device 7 is located inside the structure 400, closer to the first dynamic electromagnetic wave filter 5a to the third dynamic electromagnetic wave filter 5c, or is located inside the structure 400.

[0235] The second interference wave generating device 7 receives the filter frequencies of the first dynamic electromagnetic wave filter 5a to the third dynamic electromagnetic wave filter 5c determined by the modulation signal generating unit 3, namely the frequencies fE1 (Hz), fE2 (Hz), and fE3 (Hz) of the electromagnetic waves emitted from the device 200, and emits interference electromagnetic waves with frequencies equal to fE1 (Hz), fE2 (Hz), and fE3 (Hz).

[0236] Next, the operation of the information leakage prevention shielding device 100 will be explained.

[0237] The electromagnetic waves with frequencies fE1 (Hz), fE2 (Hz), and fE3 (Hz) emitted from the device 200 are superimposed with the interfering electromagnetic waves with frequencies fE1 (Hz), fE2 (Hz), and fE3 (Hz) emitted from the second interference wave generating device 7 and are incident on the first dynamic electromagnetic wave filter 5a to the third dynamic electromagnetic wave filter 5c.

[0238] Similar to the operation of the information leakage prevention shielding device 100 in Embodiment 1, the modulation signal generation unit 3 determines the filter frequency for the first dynamic electromagnetic wave filter 5a to the third dynamic electromagnetic wave filter 5c and generates a time variation pattern based on the selected modulation method.

[0239] The control signal output unit 4 outputs a frequency setting signal for setting the filter frequency and a modulation signal based on the selected modulation method to the first dynamic electromagnetic wave filter 5a to the third dynamic electromagnetic wave filter 5c.

[0240] The first dynamic electromagnetic wave filter 5a to the third dynamic electromagnetic wave filter 5c have their filter frequencies set by a frequency setting signal. By using a modulation signal, the transmission phase is switched over time. This modulates the electromagnetic wave emitted from device 200, which contains superimposed interference electromagnetic waves emitted from the second interference wave generating device 7, and emits leakage electromagnetic waves with high-order harmonic components at frequencies fL1 (Hz) to fL10 (Hz).

[0241] Therefore, the leakage electromagnetic waves with high-order harmonic components with frequencies fL1 (Hz) to fL10 (Hz) from the first dynamic electromagnetic wave filter 5a to the third dynamic electromagnetic wave filter 5c are superimposed on the leakage electromagnetic waves based on the electromagnetic waves emitted from the device 200, and the leakage electromagnetic waves based on the interference electromagnetic waves emitted from the second interference wave generating device 7.

[0242] Therefore, it is difficult for eavesdroppers to determine the frequency of the leaked electromagnetic waves.

[0243] As a result, it is possible to interfere with the frequency tuning of the leaked electromagnetic waves, and also to interfere with the accumulation of image data required for averaging.

[0244] Furthermore, by limiting the interfering electromagnetic waves to the frequency emitted from the device 200, not only can the power required for the emission of interfering electromagnetic waves from the second interfering wave generating device 7 be minimized, but the possibility of the interfering electromagnetic waves from the second interfering wave generating device 7 causing wireless interference to other devices can also be reduced.

[0245] Modulation is performed in the first dynamic electromagnetic wave filter 5a to the third dynamic electromagnetic wave filter 5c according to the numerical examples 1 and 2 of modulation method 2. When the leakage electromagnetic wave from the first dynamic electromagnetic wave filter 5a to the third dynamic electromagnetic wave filter 5c has n-th order harmonic components and diffuses, the number and amplitude of the high-order harmonic components are large, and the interference to the frequency tuning of the leakage electromagnetic wave is greater.

[0246] Thus, even if the number of frequencies of the leakage electromagnetic waves from the first dynamic electromagnetic wave filter 5a to the third dynamic electromagnetic wave filter 5c is increased, the frequency of the interference electromagnetic waves from the second interference wave generating device 7 can be the frequency of the electromagnetic waves emitted from the device 200. Therefore, a simple electromagnetic wave generating device can be used as the second interference wave generating device 7.

[0247] In addition, the second interference wave generating device 7 is configured to emit interference electromagnetic waves with frequencies that are all equal to the frequencies of the electromagnetic waves emitted from the device 200. However, it is also possible to emit interference electromagnetic waves with frequencies that are equal to a portion of the frequencies of the electromagnetic waves emitted from the device 200.

[0248] Implementation Method 4

[0249] use Figure 10 The information leakage prevention shielding device 100 of Embodiment 4 will be described.

[0250] The information leakage prevention shielding device 100 of Embodiment 4 differs from the information leakage prevention shielding device 100 of Embodiment 1 in that a third interference wave generating device 8 and an interference wave dynamic electromagnetic wave filter 5d are added. Otherwise, it is the same as the information leakage prevention shielding device 100 of Embodiment 1.

[0251] exist Figure 10 In, with Figure 2 The same labels indicate the same or equivalent parts.

[0252] In the information leakage prevention shielding device 100 of Embodiment 4, the structure is the same as that of the information leakage prevention shielding device 100 of Embodiment 1, except for the third interference wave generating device 8 and the dynamic electromagnetic wave filter 5d for interference waves. Therefore, the description is omitted and the description will focus on the third interference wave generating device 8 and the dynamic electromagnetic wave filter 5d for interference waves.

[0253] The information leakage prevention shielding device 100 of embodiment 4 intentionally superimposes the leakage electromagnetic waves based on the third interference wave generating device 8 and the interference wave dynamic electromagnetic wave filter 5d into the leakage electromagnetic waves from the first dynamic electromagnetic wave filter 5a to the third dynamic electromagnetic wave filter 5c, thereby improving the information leakage prevention effect.

[0254] The third interference wave generating device 8 is a device that radiates radio waves by means of radiating elements such as antennas.

[0255] The third interference wave generating device 8 is located on the side farther away from the eavesdropping device 300 than the first dynamic electromagnetic wave filter 5a to the third dynamic electromagnetic wave filter 5c, and on the side closer to the device 200 than the first dynamic electromagnetic wave filter 5a to the third dynamic electromagnetic wave filter 5c.

[0256] That is, the third interference wave generating device 8 is located inside the structure 400, closer to the first dynamic electromagnetic wave filter 5a to the third dynamic electromagnetic wave filter 5c, or is located inside the structure 400.

[0257] The third interference wave generating device 8 emits an interference electromagnetic wave with a frequency fD1 that is different from the filter frequencies of the first dynamic electromagnetic wave filters 5a to the third dynamic electromagnetic wave filters 5c determined by the modulation signal generating unit 3, i.e., the frequency of the electromagnetic wave emitted from the device 200.

[0258] Frequency fD1 is selected from the frequencies transmitted by the first dynamic electromagnetic wave filter 5a to the third dynamic electromagnetic wave filter 5c without being attenuated and modulated.

[0259] The interference wave is operated by using the frequency fD1 of the interference electromagnetic wave from the third interference wave generating device 8 as the filter frequency by the dynamic electromagnetic wave filter 5d.

[0260] The dynamic electromagnetic wave filter 5d for interference waves has the same structure as the first dynamic electromagnetic wave filter 5a to the third dynamic electromagnetic wave filter 5c.

[0261] The interference wave dynamic electromagnetic wave filter 5d is arranged side by side with the first dynamic electromagnetic wave filter 5a to the third dynamic electromagnetic wave filter 5c. The interference wave dynamic electromagnetic wave filter 5d and the first dynamic electromagnetic wave filter 5a to the third dynamic electromagnetic wave filter 5c can also be connected sequentially to form a single structure.

[0262] The interference wave dynamic electromagnetic wave filter 5d sets the filter frequency to frequency fD1 by using a frequency setting signal output from the control signal output unit 4 based on the frequency fD1 determined by the modulation signal generation unit 3. It then modulates the interference electromagnetic wave from the third interference wave generating device 8 by using an interference modulation signal based on the time variation mode of the modulation method generated by the modulation signal generation unit 3, and emits interference leakage electromagnetic waves.

[0263] The modulation method used for the interference modulation signal is as follows: no attenuation of the interference electromagnetic wave, that is, the transmission amplitude is 0dB, the transmission phase is switched, and the frequency of the interference leakage electromagnetic wave emitted from the interference wave dynamic electromagnetic wave filter 5d is part or all of the frequency of the leakage electromagnetic wave of the first dynamic electromagnetic wave filter 5a to the third dynamic electromagnetic wave filter 5c.

[0264] Therefore, leakage electromagnetic waves with frequencies fL1 (Hz) to fL10 (Hz) from the interference wave dynamic electromagnetic wave filter 5d are superimposed on the leakage electromagnetic waves with high-order harmonic components from the first dynamic electromagnetic wave filter 5a to the third dynamic electromagnetic wave filter 5c.

[0265] Therefore, it is difficult for eavesdroppers to determine the frequency of the leaked electromagnetic waves.

[0266] As a result, it is possible to interfere with the frequency tuning of the leaked electromagnetic waves, and also to interfere with the accumulation of image data required for averaging.

[0267] Furthermore, the frequency fD1 of the interference electromagnetic wave emitted from the third interference wave generating device 8 can be one, so a simple radio wave generating device can be used as the third interference wave generating device 8.

[0268] Furthermore, by setting the frequency fD1 of the interfering electromagnetic wave emitted from the third interfering wave generating device 8 to a frequency that is not attenuated and modulated by the first dynamic electromagnetic wave filter 5a to the third dynamic electromagnetic wave filter 5c, the output from the third interfering wave generating device 8 can be reduced, and the power consumption required for the emission of the interfering electromagnetic wave in the third interfering wave generating device 8 can be reduced.

[0269] Furthermore, it is possible to freely combine the various embodiments, modify any structural elements of each embodiment, or omit any structural elements in each embodiment.

[0270] Industrial availability

[0271] The information leakage prevention shielding device 100 of the present invention is applicable to devices that intentionally or unintentionally emit electromagnetic waves, such as devices that may eavesdrop on information from emitted electromagnetic waves, monitors, wireless communication devices, printers, etc.

[0272] Label Explanation

[0273] 100: Information leakage prevention shielding device; 200: Equipment; 300: Eavesdropping device; 400: Structure; 1: Electromagnetic wave detection unit; 2: Storage unit; 3: Modulation signal generation unit; 4: Signal output unit; 5a~5c: ​​First dynamic electromagnetic wave filter~Third dynamic electromagnetic wave filter; 6: First interference wave generating device; 7: Second interference wave generating device; 8: Third interference wave generating device.

Claims

1. A shielding device for preventing information leakage, comprising: The control unit outputs a frequency setting signal that sets the filter frequency for the electromagnetic waves emitted from the device, and a modulation signal based on a time-varying pattern. This time-varying mode is used to sequentially indicate multiple different transmission characteristics as time progresses; and A dynamic electromagnetic wave filter has its filter frequency set by a frequency setting signal from the control unit and its transmission characteristics, which vary with time, set by a modulation signal from the control unit. This dynamic electromagnetic wave filter transmits electromagnetic waves other than the filter frequency set by the frequency setting signal and exhibits transmission characteristics that vary with time, set by the modulation signal, for the filter frequency set by the frequency setting signal.

2. The information leakage prevention shielding device according to claim 1, wherein, The time variation mode is a time variation mode in which the transmission characteristics are randomly switched over time.

3. The information leakage prevention shielding device according to claim 1, wherein, The time variation pattern is a time variation pattern in which the transmission characteristics increase in 10 stages at a rate of 2π / 10 to 2π.

4. The information leakage prevention shielding device according to claim 1, wherein, The time variation mode is a time variation mode in which the transmission characteristic is set to 2.5sin(α(t)) and α(t) increases to 2π in 10 stages at 2π / 10 increments.

5. The information leakage prevention shielding device according to claim 1, wherein, The time variation mode is a time variation mode in which the transmission characteristics switch between the two values ​​of 0 and π.

6. The information leakage prevention shielding device according to any one of claims 1 to 5, wherein, The control unit outputs a modulation signal that repeatedly repeats the time variation pattern, and the repeated time variation pattern is a time variation pattern based on the same modulation method.

7. The information leakage prevention shielding device according to claim 1, wherein, The control unit outputs a modulation signal that repeatedly repeats the time variation pattern, and the repeated time variation patterns are different time variation patterns.

8. The information leakage prevention shielding device according to claim 1, wherein, The dynamic electromagnetic wave filter has multiple units arranged in a matrix of multiple rows and columns. These multiple units are divided into multiple groups, and each group is designated as a dynamic electromagnetic wave filter section with multiple units. The control unit outputs modulation signals based on different time-varying patterns for each of the multiple dynamic electromagnetic wave filter sections of the dynamic electromagnetic wave filter.

9. The information leakage prevention shielding device according to claim 1, wherein, The information leakage prevention shielding device has multiple dynamic electromagnetic wave filters. The control unit outputs modulation signals based on different time-varying patterns for each of the plurality of dynamic electromagnetic wave filters.

10. The information leakage prevention shielding device according to any one of claims 1 to 5, wherein, The information leakage prevention shielding device has a first interference wave generating device, which emits an interference electromagnetic wave with the same frequency as the leakage electromagnetic wave emitted from the dynamic electromagnetic wave filter.

11. The information leakage prevention shielding device according to claim 10, wherein, The first interference wave generating device is positioned on the opposite side from the side where the dynamic electromagnetic wave filter is located.

12. The information leakage prevention shielding device according to any one of claims 1 to 5, wherein, The information leakage prevention shielding device has a second interference wave generating device, which is disposed on the side of the device disposed closer to the dynamic electromagnetic wave filter, and emits an interference electromagnetic wave with the same frequency as the electromagnetic wave emitted from the device.

13. The information leakage prevention shielding device according to any one of claims 1 to 5, wherein, The information leakage prevention shielding device has the following features: A third interference wave generating device emits interference electromagnetic waves at a frequency different from the frequency of the electromagnetic waves emitted from the device; and The interference wave uses a dynamic electromagnetic wave filter, which operates by setting the frequency of the interference electromagnetic wave from the third interference wave generating device to the filter frequency.

14. The information leakage prevention shielding device according to claim 13, wherein, The frequency of the interference leakage electromagnetic wave emitted from the interference wave using the dynamic electromagnetic wave filter is equal to the frequency of the leakage electromagnetic wave emitted from the dynamic electromagnetic wave filter.

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