WO1998015161A1 - Dispositif de protection contre les champs electromagnetiques - Google Patents
Dispositif de protection contre les champs electromagnetiques Download PDFInfo
- Publication number
- WO1998015161A1 WO1998015161A1 PCT/JP1997/003556 JP9703556W WO9815161A1 WO 1998015161 A1 WO1998015161 A1 WO 1998015161A1 JP 9703556 W JP9703556 W JP 9703556W WO 9815161 A1 WO9815161 A1 WO 9815161A1
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- WIPO (PCT)
- Prior art keywords
- electromagnetic field
- shielding
- coil
- shield device
- parallel resonance
- Prior art date
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- 230000005672 electromagnetic field Effects 0.000 title claims abstract description 299
- 238000001514 detection method Methods 0.000 claims description 22
- 239000004020 conductor Substances 0.000 claims description 13
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Classifications
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
- H01J29/00—Details of cathode-ray tubes or of electron-beam tubes of the types covered by group H01J31/00
- H01J29/003—Arrangements for eliminating unwanted electromagnetic effects, e.g. demagnetisation arrangements, shielding coils
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R1/00—Details of instruments or arrangements of the types included in groups G01R5/00 - G01R13/00 and G01R31/00
- G01R1/02—General constructional details
- G01R1/18—Screening arrangements against electric or magnetic fields, e.g. against earth's field
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R29/00—Arrangements for measuring or indicating electric quantities not covered by groups G01R19/00 - G01R27/00
- G01R29/08—Measuring electromagnetic field characteristics
- G01R29/0807—Measuring electromagnetic field characteristics characterised by the application
- G01R29/0814—Field measurements related to measuring influence on or from apparatus, components or humans, e.g. in ESD, EMI, EMC, EMP testing, measuring radiation leakage; detecting presence of micro- or radiowave emitters; dosimetry; testing shielding; measurements related to lightning
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01Q—ANTENNAS, i.e. RADIO AERIALS
- H01Q1/00—Details of, or arrangements associated with, antennas
- H01Q1/52—Means for reducing coupling between antennas; Means for reducing coupling between an antenna and another structure
- H01Q1/526—Electromagnetic shields
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04B—TRANSMISSION
- H04B15/00—Suppression or limitation of noise or interference
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R29/00—Arrangements for measuring or indicating electric quantities not covered by groups G01R19/00 - G01R27/00
- G01R29/08—Measuring electromagnetic field characteristics
- G01R29/0864—Measuring electromagnetic field characteristics characterised by constructional or functional features
- G01R29/0878—Sensors; antennas; probes; detectors
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
- H01J2229/00—Details of cathode ray tubes or electron beam tubes
- H01J2229/0007—Elimination of unwanted or stray electromagnetic effects
- H01J2229/0015—Preventing or cancelling fields leaving the enclosure
- H01J2229/0023—Passive means
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
- H04N5/00—Details of television systems
- H04N5/64—Constructional details of receivers, e.g. cabinets or dust covers
- H04N5/645—Mounting of picture tube on chassis or in housing
Definitions
- the present invention relates to a device for shielding an electromagnetic field leaking from the inside of an electric device or the like, and particularly to a resonance-type shield and an active shield using electronic components.
- Electric and electronic devices generate leakage electromagnetic fields, albeit weakly. Such electromagnetic fields must be shielded because they can cause other equipment to malfunction or adversely affect the human body.
- FIGS. 21 (a) and 21 (b) are diagrams for explaining a conventional method of shielding an electromagnetic field by a shield member.
- FIG. 21 (a) shows a state in which an electromagnetic field generated inside an electric device leaks out of the opening 11 of the housing 10 thereof.
- FIG. 21 (b) shows a state in which the opening 11 is covered with the shield member 12 in order to block the leakage electromagnetic field.
- the electromagnetic field can be shielded by reflecting the leaked electromagnetic field inside the housing by eddy current generated as a reaction to the leaked electromagnetic field.
- the shield member 12 is a magnetic material, a material having a permeability higher than that of air can be used to confine and shield the magnetic field of the leakage electromagnetic field.
- the strength of the shieldable magnetic field is limited in the shield member 12 made of a magnetic material. For example, it is extremely difficult to shield high magnetic fields, such as over 1.5 Tesla.
- the present invention has been made in view of such a problem, and an electromagnetic field that can shield an electromagnetic field leaking from an opening of an equipment housing without closing the opening without closing the opening.
- the primary purpose is to provide a shield device.
- a second object of the present invention is to provide a flexible electromagnetic field shield device which can easily cope with various types of electromagnetic fields having different intensities and frequencies.
- a third object of the present invention is to provide a uniform shielding effect without changing component parts or materials, even in the case of a fluctuating leakage electromagnetic field whose intensity and frequency change with time. It is to provide an electromagnetic field shielding device capable of performing the following. Further, a fourth object of the present invention is to provide an electromagnetic field shielding device capable of shielding against a strong magnetic field exceeding 1.5 Tesla. Disclosure of the invention
- an electromagnetic field detecting means including a coil or the like for detecting a leakage electromagnetic field, and a circuit constant is determined in advance so as to tune to a frequency of an electromotive force induced by the electromagnetic field detecting means. And a resonance means with reduced power consumption.
- the electromotive force induced in the electromagnetic field detecting means by the leakage electromagnetic field is supplied to the resonance means, where energy is consumed, so that the intensity of the leakage electromagnetic field is attenuated and shielded.
- the first object can be achieved because the electromagnetic field leaking from the opening can be shielded without closing the opening while maintaining the opening state.
- the resonance means may be a parallel resonance circuit composed of L, C, and R electronic components, or may be a conductor that can be handled as a distributed constant circuit.
- the CR electronic component is a circuit component having a variable circuit constant, and further, means for specifying a center frequency of the electromotive force, and a resonance at the specified center frequency. Means for determining and controlling the circuit constant as described above.
- the device can change the resonance frequency or change the amount of energy consumption following the leakage electromagnetic field whose frequency or intensity changes. Achieved.
- the present invention provides an electromagnetic field detecting means for detecting a leakage electromagnetic field, an electromagnetic field generating means for generating an electromagnetic field, and an electromagnetic field for canceling the electromagnetic field detected by the electromagnetic field detecting means.
- An active electromagnetic field shielding device including a control unit for controlling the electromagnetic field generating unit may also be provided.
- the electromagnetic field detecting means and the electromagnetic field generating means may be hollow coils having a hollow portion common or having the same central axis, and may be provided so as to overlap an outer periphery of an opening or the like of an electric device from which the electromagnetic field leaks. .
- FIG. 1 shows the appearance of an electromagnetic field shield device 20 according to the first embodiment.
- FIG. 2 is an electric circuit diagram of the electromagnetic field shield device 20.
- FIG. 3 is an overall external view of the case where the electromagnetic field shield device 20 is attached to the outside of the housing 10 of the electric device along the periphery of the opening 11.
- Fig. 4 (a) is an overall external view of the same electromagnetic field shield device 20 when it is mounted inside the housing 10 of an electric device
- Fig. 4 (b) is a sectional view taken along the line AA in Fig. 4 (a). It is a figure.
- FIG. 5 (a) to 5 (c) show simulation models for verifying the shielding effect of the electromagnetic field shield device 20
- FIG. 5 (a) is a perspective view
- FIG. 5 (b) is a top view
- FIG. (c) is a sectional view taken along the line BB in FIG. 5 (b).
- FIG. 6 shows the distribution of leakage magnetic flux lines on the BB section in FIG. 5 (b) when the electromagnetic field shield device 20 is not placed in the models shown in FIGS. 5 (a) to 5 (c).
- FIG. 7 shows the distribution of leakage magnetic flux lines on the BB section in FIG. 5 (b) when the electromagnetic field shield device 20 is placed in the models shown in FIGS. 5 (a) to 5 (c).
- FIG. 8 is a graph showing the shielding effect of the leakage electromagnetic field when the inductance of the coil 23 of the electromagnetic field shielding device 20 is changed.
- FIG. 9 is an external view of the electromagnetic field shield device 40 according to the first modification of the first embodiment.
- FIG. 10 shows a distributed constant circuit for explaining the shielding principle of the electromagnetic field shielding device 40.
- FIG. 11 is a circuit diagram generalizing each of the resonance type electromagnetic field shield device and the electromagnetic field shield device using the distributed constant circuit according to the present invention.
- FIG. 12 is a block diagram showing a configuration of the electromagnetic field shield device 30 according to the second modification of the first embodiment.
- FIG. 13 is a block diagram showing a detailed configuration of the variable reactor 34 of the electromagnetic field shielding device 30. As shown in FIG.
- FIG. 14 is a block diagram showing a detailed configuration of the circuit constant control unit 33 of the electromagnetic field shield device 30.
- FIG. 15 shows an appearance of an electromagnetic field shield device 50 according to the second embodiment.
- FIG. 16 is a block diagram showing the configuration of the electromagnetic field shield device 50. As shown in FIG.
- Fig. 17 (a) shows the waveform of the induced electromotive force Vs generated in the electromagnetic field detector 51 of the electromagnetic field shield device 50
- Fig. 17 (b) shows the waveform of the signal of the center frequency component of the induced electromotive force Vs.
- Figure 17 (c) shows the waveform of the delay signal VI output from the delay unit 53b.
- FIG. 18 shows an example in which an electromagnetic field shield device 20 is provided inside the front surface of the CRT device.
- FIG. 19 (a) shows an example in which the electromagnetic field shield device 20 is provided inside the front surface of the mobile phone, and
- FIG. 19 (b) is a cross-sectional view taken along the line CC in FIG. 19 (a).
- FIG. 20 (a) shows an example in which the electromagnetic shield device 20 is provided around the disk slot of the floppy disk drive device provided in the personal computer main unit
- Fig. 20 (b) shows the example in Fig. 20 (a).
- FIG. FIG. 21A is an external view showing a state in which an electromagnetic field generated inside the electric device leaks from the opening 11 of the housing 10.
- FIG. 21 (b) is a view for explaining a conventional technique in which the opening 11 is covered with the shield member 12 to block the leakage electromagnetic field.
- Embodiment 1 relates to a resonance-type electromagnetic field shielding device using electronic components.
- FIG. 1 shows the appearance of an electromagnetic field shield device 20 according to the first embodiment.
- FIG. 2 is an electric circuit diagram of the electromagnetic field shield device 20.
- FIG. 3 is an overall external view of the case where the electromagnetic field shield device 20 is attached to the outside of the housing 10 in order to shield an electromagnetic field leaking from the opening 11 of the housing 10 of the electric device.
- FIG. 4 (a) is an overall external view when the electric device is mounted inside the housing 10, and FIG. 4 (b) is a cross-sectional view along AA in FIG. 4 (a).
- the electromagnetic field shield device 20 includes an electromagnetic field detecting coil 21, a capacitor 22 mounted on a circuit board 25, a coil 23, and a resistor 24.
- the electromagnetic field detecting coil 21 is a hollow coil for detecting a leaked electromagnetic field, and is formed by winding an enamel-coated copper wire in an L shape so as to surround the outer periphery of the opening 11.
- an induced electromotive force Vs proportional to the change of the interlinking magnetic flux ⁇ is generated as shown in the following equation 1.
- Vs — N
- this electromagnetic field shield device 20 is strictly for detecting a change in leakage “magnetic flux” (AC leakage magnetic flux). Since the electromagnetic field is generated, it can be said that the electromagnetic field shield device 20 detects the “electromagnetic field”.
- the capacitor 22, the coil 23, and the resistor 24 mounted on the circuit board 25 are loads when the electromotive force V s induced in the electromagnetic field detecting coil 21 is used as a signal source, and the resonance frequency f O constitutes a parallel resonance circuit represented by the following equation (2).
- C is the capacitance (F) of the capacitor 22
- L 1 is the inductance (H) of the coil 23
- R is the resistance value ( ⁇ ) of the resistor 24.
- the specific values of C, L 1, and R are determined by the center frequency (the frequency of the most signal component in the frequency spectrum) of the leakage magnetic flux to be shielded by the electromagnetic shielding device 20. This is a value determined in advance so as to match the resonance frequency f 0 represented by the above equation (2).
- an electromagnetic shielding device that shields a leakage electromagnetic field of 4788 KHz is realized from a capacitor 22 of 0.01 ⁇ F, a coil 23 of 10 H, and a resistor 24 of 10 ⁇ . .
- FIGS. 5 (a) to 5 (c) show simulation models for verifying the shielding effect of the electromagnetic field shield device 20.
- FIG. 5 (a) is a perspective view
- FIG. 5 (b) is a top view
- FIG. 5 (c) is a sectional view taken along the line BB in FIG. 5 (b).
- This model consists of a coil 13 that generates a radiated electromagnetic field of 10 OKHz, a lower housing 10a with an open top that houses the coil, and an upper opening 14 with the lower housing 10a and the opening gap 14. And an electromagnetic field shield device 20 arranged to shield an electromagnetic field leaking forward from the opening gap 14 of the upper case 10b.
- the lower housing 10a and the upper housing 10b respectively correspond to the five surfaces and the upper surface excluding the upper surface of the originally rectangular parallelepiped housing, and these are made of a magnetic material.
- FIG. 6 shows the distribution of leakage magnetic flux lines on the BB cross section in FIG. 5B when the electromagnetic field shield device 20 is not placed in the above model.
- Fig. 7 shows the model shown in Fig. 5 with the electromagnetic shielding device 20 placed.
- (b) shows the distribution of leakage magnetic flux lines on the BB cross section.
- Figure 8 shows the shielding effect of the leakage electromagnetic field when the inductance of the coil 23 is changed while the capacitance of the capacitor 22 and the resistance of the resistor 24 are fixed at a fixed value and the inductance of the coil 23 is changed. It is a graph. The vertical axis shows the shielding effect of the leakage magnetic field, that is, the opening gap when the electromagnetic field shielding device 20 is not placed 14 The electromagnetic field shielding device 20 when the strength of the leakage magnetic field at the position 4 is 1 It shows the strength of the stray magnetic field when is placed.
- the maximum shielding effect can be obtained. It can be seen that it can be obtained.
- the electromagnetic field that is going to pass through the electromagnetic field detection coil 21 is shielded. Since the coil 21 can be formed in any shape, the electromagnetic field leaking from the opening can be shielded without closing the opening of the equipment housing while maintaining the open state. it can.
- an electromagnetic field shield device 40 using a distributed constant circuit will be described as a first modification of the electromagnetic field shield device 20 according to the first embodiment.
- FIG. 9 is an external view of the electromagnetic field shield device 40 according to the first modification.
- This electromagnetic field shield device 40 is a shield device for an AC leakage electromagnetic field of a higher frequency than that of the first embodiment, that is, a high frequency that can treat the device itself as a distributed constant circuit. It is composed of an electromagnetic field detecting coil 21 and a plate-shaped conductor 41.
- the conductor 41 is, for example, an aluminum plate or the like. Both ends 41 a and 41 b connected to the electromagnetic field detecting coil 21 are arranged so as to face each other, and the main body 41 except for both ends 41 a and 41 b is provided. c is bent into a rectangular loop.
- the conductor 41 has a resistance value inherent to the metal material constituting the conductor 41, has a capacitance due to opposing end portions 41a and 41b, and has a main body portion 41c of 1%. Since it corresponds to a turn coil, it can be said that it constitutes a cavity resonator corresponding to the resonance circuits 22 to 24 of the first embodiment. Therefore, with the electromagnetic field shield device 40 of the first modification, the same shielding effect as that of the first embodiment can be obtained against a high-frequency leakage electromagnetic field.
- the shielding principle using a distributed constant circuit such as the present electromagnetic field shielding device 40, and the conditions for exhibiting the shielding effect will be described below from the viewpoint of the distribution constant circuit.
- the electromagnetic field shield device 40 includes a high-frequency power supply 42 corresponding to the electromagnetic field detection coil 21, a line 43 for transmitting power therefrom, and a load 44 It can be regarded as a distributed constant circuit composed of
- V (x) Vie— Tx + v 2 e + a X (Equation 5) ⁇
- Equations 8 and 9 must be satisfied.
- V2 0
- the power supplied from 2 can be consumed by the load 4 4 without being reflected.
- the high-frequency leakage electromagnetic field is shielded by matching the impedance between the AC electromagnetic field targeted by the electromagnetic field shielding device 40 and the line and load formed by the conductor 41.
- this principle is based on the fact that the electromagnetic field shield device 20 in the first embodiment is connected to the load circuits 22 to 24 that resonate with the target AC electromagnetic field, thereby shielding the relatively low frequency leakage electromagnetic field. It can be said that the principle is basically the same. Shielding Principles in Embodiment 1 and Modification 1 The conditions for exhibiting the shielding effect are generalized as follows.
- FIG. 11 is a circuit diagram generalizing each of the resonance type electromagnetic field shield device and the electromagnetic field shield device using the distributed constant circuit according to the present invention.
- These electromagnetic shielding devices 20 and 40 can be considered to be composed of an induced electromotive force 42 due to a leakage electromagnetic field, a load 44 and a four-terminal network 45 connecting them.
- each s parameter is determined so that S 1 1 (voltage reflection coefficient) approaches zero as much as possible.
- the lumped constant element is used based on the principle that the energy of the power source 42 is transferred only in one direction by the four-terminal network 45 and is consumed by the load 44 to shield the leakage electromagnetic field.
- the electromagnetic field shield device 20 by parallel resonance and the electromagnetic field shield device 40 by impedance matching using a distributed constant circuit are common.
- FIG. 12 is a block diagram showing the configuration of the electromagnetic field shield device 30 according to the second modification.
- the electromagnetic field shield device 30 includes an electromagnetic field detecting coil 21, a waveform analysis unit 32, a circuit constant control unit 33, a variable rear turtle 34, a variable capacitor 35, and a variable resistor 36.
- This device 30 is the same as the first embodiment in that it is a resonance type shield device, but has a function of tuning to the frequency of the leakage electromagnetic field detected by the electromagnetic field detecting coil 21. Different from 1.
- the waveform analysis unit 32 is composed of a DSP (Digital Signal Processor) or the like that executes FFT (Fast Fourier Transformation), and calculates the center frequency f O of the electromotive force Vs induced in the electromagnetic field detection coil 21 at regular time intervals. Identify and notify circuit constant control unit 33.
- DSP Digital Signal Processor
- FFT Fast Fourier Transformation
- the variable reactor 34 includes a plurality of MOS transistors 37a to 37d as switches, a plurality of coils 38a to 38d, and a MOS transistor 37a to 37d. It consists of a decoder circuit 39 connected to the gate, and changes the inductance stepwise by turning on only one of the MOS transistors 37a to 37d based on an instruction from the circuit constant control unit 33. .
- the variable capacitor 35 is a variable capacitance diode or the like, and its capacitance changes within a certain range according to a control voltage from the circuit constant control unit 33.
- the variable resistor 36 is an MS transistor or the like, and the resistance value changes within a certain range according to a control voltage from the circuit constant control unit 33.
- the circuit constant control unit 33 controls the circuit constants of the electronic components 34 to 36 according to the above equation 2 so that the parallel resonance circuits 34 to 36 are tuned to the center frequency f O notified from the waveform analysis unit 32. I do.
- FIG. 14 is a block diagram showing a detailed configuration of the circuit constant control unit 33.
- the circuit constant control unit 33 includes a circuit constant storage table 33b in which the inductance to be selected for each center frequency f O notified from the waveform analysis unit 32, the adjustable circuit constant range of each electronic component, and the like are recorded in advance, The contents of the circuit constant storage table 33 b and A circuit constant calculator 33 a for calculating the optimum circuit constants of the electronic components 34 to 36 according to the center frequency f 0 notified from the waveform analyzer 32 and the above equation 2, and It is composed of DZA converters 33c and 33d that convert digital data into control voltage.
- the electromagnetic field shield device 30 According to the electromagnetic field shield device 30 according to the second modification configured as described above, even if the frequency of the AC electromagnetic field interlinking the electromagnetic field detection coil 21 changes, the change follows the change. Since the circuit constants of the circuit components 34 to 36 are adjusted and tuned, a constant shielding effect is always exerted. In other words, an electromagnetic field shield device 30 that can exhibit a shielding effect uniformly without changing components or materials depending on the frequency of the target leakage electromagnetic field is realized.
- Embodiment 2 relates to an active shield provided with an electromagnetic field generating means for canceling a leakage electromagnetic field.
- FIG. 15 shows the appearance of an electromagnetic field shield device 50 according to the second embodiment.
- the electromagnetic field shield device 50 includes an electromagnetic field detection unit 51, an electromagnetic field generation unit 52, and a leakage electromagnetic field control unit 53.
- the electromagnetic field detecting section 51 is the same as the electromagnetic field detecting coil 21 in the first embodiment.
- the electromagnetic field generating section 52 is a hollow coil in which a conductor is wound in the same shape and direction as the electromagnetic field detecting section 51, and the hollow portion of the electromagnetic field generating section 51 and the above-mentioned hollow section are shared or have the same central axis. It is used in close contact with or overlaid to generate a reaction electromagnetic field that cancels out a leakage electromagnetic field that links the electromagnetic field detection unit 51.
- the leakage electromagnetic field control unit 53 generates the above-described reaction electromagnetic field by generating an electromotive force having a phase opposite to the induced electromotive force generated in the electromagnetic field detection unit 51 and supplying the generated electromotive force to the electromagnetic field generation unit 52. It is a control circuit.
- FIG. 16 is a functional block diagram showing the configuration of the electromagnetic field shield device 50.
- the leakage electromagnetic field control unit 53 further includes a band-pass filter 53a, a delay unit 53b, and a power amplification unit 53c.
- FIGS. 17 (a) to 17 (c) are waveform diagrams for explaining the phase relationship of signals output from the respective components of the device 50, and FIG. 17 (a) shows the induction generated in the electromagnetic field detecting section 51.
- Figure 17 (b) shows the waveform of the center frequency component signal of the induced electromotive force Vs (broken line) and the waveform of the filter signal V0 output from the band-pass filter 53a (solid line).
- (c) shows the waveform of the delay signal VI output from the delay unit 53b (this is assumed to be equal in phase to the voltage waveform V2 output from the power amplification unit 53c).
- the band-pass filter 53a is an active filter composed of an operational amplifier or the like for removing unnecessary frequency components from the induced electromotive force Vs generated in the electromagnetic field detection unit 51, and the induction generated in the electromagnetic field detection unit 51. After amplifying the electromotive force Vs, it passes only the predetermined frequency component V0 of the band to be shielded and sends it to the delay unit 53b.
- the delay unit 53b is provided by a delay line or the like for delaying the phase of the input signal V0 so that the leakage electromagnetic field interlinking the electromagnetic field detection unit 51 and the electromagnetic field generated by the electromagnetic field generation unit 52 cancel each other. For example, when the center frequency component V0 is output after being delayed by td1 in the band-pass filter 53a, the phase delay is further delayed by td2 to generate a total phase delay of 180 degrees.
- the power amplifier 53c is an AC amplifier that amplifies the power of the signal from the delay unit 53b, and supplies the electromagnetic field generator 52 with an AC current for generating the above-mentioned reaction electromagnetic field.
- the electromagnetic field detection unit 51 generates an induced electromotive force Vs proportional to a change in the interlinking magnetic flux, as shown in the following Expression 11.
- the delay unit 5 3b further delays the input signal V0 by td2 to generate a signal VI represented by the following expression 13 and delayed by a phase ⁇ from the center frequency component of the original induced electromotive force Vs. I do.
- the power amplifying unit 53 c generates the following signal V2, which is obtained by amplifying the delayed signal VI by k times, so that the electromagnetic field generating unit 52 generates an electromagnetic field enough to cancel the leakage electromagnetic field. generate. ( ⁇ 1 4)
- the electromagnetic field shield device 50 causes the leakage electromagnetic field of a specific frequency detected by the electromagnetic field detection unit 51 to be equal to the electromagnetic field detection unit. Since the electromagnetic field generated by the electromagnetic field generator 52 superimposed on 51 cancels the electromagnetic field, the electromagnetic field in the hollow of the electromagnetic field detector 51 no longer exists, and the leakage electromagnetic field is shielded. You.
- the coils constituting the electromagnetic field detection unit 51 and the electromagnetic field generation unit 52 are formed in any shape. Therefore, the electromagnetic field leaking from the opening can be shielded without closing the opening of the device housing without closing the opening.
- the electromagnetic field detecting unit 51 is a coil for detecting an alternating electromagnetic field.
- the present invention is not limited to this.
- a vertical coil for detecting an electric field may be used.
- An antenna or a Hall element that detects not only AC but also DC magnetic fields may be used.
- the leakage electromagnetic field control unit 53 performs control according to the characteristics of the electromagnetic field detection unit 51, so that various types of leakage electromagnetic fields can be shielded.
- the electromagnetic field detecting unit 51 and the electromagnetic field generating unit 52 are separate coils, but these may be shared by one coil. Specifically, a single coil that performs both detection and generation of the electromagnetic field is placed in the leakage electromagnetic field, and power is supplied to the coil so that the induced electromotive force Vs becomes zero. Control it.
- the electromagnetic field shield device 50 of the second embodiment targets a leakage electromagnetic field of a specific frequency.
- the electromagnetic field shield device 30 of the second modification of the first embodiment the By further providing the circuit 32 and the circuit constant control unit 33, a dynamic active shield that can shield following changes in the leakage electromagnetic field can be provided.
- one electromagnetic field shield device was used to shield the leakage electromagnetic field, but a plurality of electromagnetic field shield devices corresponding to the distribution of the leakage electromagnetic field were installed in the equipment. Can also be attached.
- one electromagnetic field shield device may be provided with a plurality of electromagnetic field detection coils, or may be provided with a plurality of electromagnetic field generation coils.
- FIG. 18 shows an example in which an electromagnetic field shield device 20 is provided inside the front surface of the CRT device.
- FIGS. 19 (a) and (b) show an example in which an electromagnetic field shield device 20 is provided inside the front of a portable telephone.
- FIGS. 20 (a) and (b) show an example in which an electromagnetic field shield device 20 is provided around a disk insertion slot of a floppy disk drive device provided in a personal computer main body.
- the electromagnetic field leaking from the opening of the device housing is maintained without closing the opening. It is possible to manufacture a shield device that can easily handle various types of electromagnetic fields with different strengths and frequencies without changing the components and materials, Even with a fluctuating leakage electromagnetic field where the strength and frequency change, a uniform shielding effect can be exhibited.
- the electromagnetic field shielding device is a computer display.
- a component to shield electromagnetic fields leaking from optical devices such as optical devices, mobile phones, and other devices that generate high magnetic fields such as MRI (Magnetic Resonance Imaging).
- the device is particularly suitable for use as an electronic component that easily shields an electromagnetic field leaking through a disk slot or a door of a floppy disk drive without closing the opening.
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- Electromagnetism (AREA)
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- Engineering & Computer Science (AREA)
- Computer Networks & Wireless Communication (AREA)
- Signal Processing (AREA)
- Shielding Devices Or Components To Electric Or Magnetic Fields (AREA)
Description
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Priority Applications (4)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
JP50364898A JP3176636B2 (ja) | 1996-10-04 | 1997-10-03 | 電磁界シールド装置 |
US09/077,392 US6249006B1 (en) | 1996-10-04 | 1997-10-03 | Electromagnetic field shielding device |
DE69728650T DE69728650D1 (de) | 1996-10-04 | 1997-10-03 | Schutzvorrichtung vor elektromagnetischen feldern |
EP97942249A EP0880311B1 (en) | 1996-10-04 | 1997-10-03 | Electromagnetic field shielding device |
Applications Claiming Priority (2)
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JP26427496 | 1996-10-04 | ||
JP8/264274 | 1996-10-04 |
Publications (1)
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WO1998015161A1 true WO1998015161A1 (fr) | 1998-04-09 |
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PCT/JP1997/003556 WO1998015161A1 (fr) | 1996-10-04 | 1997-10-03 | Dispositif de protection contre les champs electromagnetiques |
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US (1) | US6249006B1 (ja) |
EP (1) | EP0880311B1 (ja) |
JP (1) | JP3176636B2 (ja) |
DE (1) | DE69728650D1 (ja) |
WO (1) | WO1998015161A1 (ja) |
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- 1997-10-03 JP JP50364898A patent/JP3176636B2/ja not_active Expired - Fee Related
- 1997-10-03 WO PCT/JP1997/003556 patent/WO1998015161A1/ja active IP Right Grant
- 1997-10-03 EP EP97942249A patent/EP0880311B1/en not_active Expired - Lifetime
- 1997-10-03 US US09/077,392 patent/US6249006B1/en not_active Expired - Lifetime
- 1997-10-03 DE DE69728650T patent/DE69728650D1/de not_active Expired - Lifetime
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JPH02159595A (ja) * | 1988-12-13 | 1990-06-19 | Fujita Corp | 磁気シールドルーム用窓 |
JPH03280595A (ja) * | 1990-03-29 | 1991-12-11 | Nippon Sharyo Seizo Kaisha Ltd | 磁気遮へい方法 |
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KR100752835B1 (ko) * | 2000-02-23 | 2007-08-29 | 루센트 테크놀러지스 인크 | 간섭 억제 장치 및 방법 |
JP2004327710A (ja) * | 2003-04-24 | 2004-11-18 | Ricoh Co Ltd | 電子応用装置 |
JP2005045127A (ja) * | 2003-07-24 | 2005-02-17 | Tokai Univ | 電磁界感応機能材料 |
JP4581105B2 (ja) * | 2003-07-24 | 2010-11-17 | 学校法人東海大学 | 電磁界感応機能体 |
JP2005347393A (ja) * | 2004-06-01 | 2005-12-15 | Tokai Univ | 電磁界感応機能性材料 |
JP4542827B2 (ja) * | 2004-06-01 | 2010-09-15 | 学校法人東海大学 | 電磁界感応機能体 |
JP2007129049A (ja) * | 2005-11-02 | 2007-05-24 | Takenaka Komuten Co Ltd | 磁気シールドルーム |
JP2017022272A (ja) * | 2015-07-10 | 2017-01-26 | 公益財団法人鉄道総合技術研究所 | アクティブシールド設置位置決定方法及びアクティブシールド設置位置決定装置 |
CN109407120A (zh) * | 2018-10-30 | 2019-03-01 | 泰州市计量测试院 | 一种基于北斗/gps的gnss信号模拟器校准装置 |
CN109407120B (zh) * | 2018-10-30 | 2023-07-28 | 泰州市计量测试院 | 一种基于北斗/gps的gnss信号模拟器校准装置 |
Also Published As
Publication number | Publication date |
---|---|
US6249006B1 (en) | 2001-06-19 |
EP0880311B1 (en) | 2004-04-14 |
DE69728650D1 (de) | 2004-05-19 |
EP0880311A1 (en) | 1998-11-25 |
JP3176636B2 (ja) | 2001-06-18 |
EP0880311A4 (en) | 2000-08-09 |
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