JP2010010268A - Jamming electromagnetic wave-reducing device and electronic equipment - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a jamming electromagnetic wave-reducing device or electronic equipment exhibiting an electromagnetic wave-reducing effect in a wide band against linear polarization. <P>SOLUTION: The jamming electromagnetic wave-reducing device reducing jamming electromagnetic waves generated from the electronic equipment includes a longitudinal structure 1 constituted by electrically connecting two conductive members arrayed in the same direction as the longitudinal direction of an electromagnetic wave noise source generating the jamming electromagnetic waves via a resistor 2, and at least a pair of longitudinal structures 1 latitudinally disposed about the structure 1 symmetrically. Conductive members which are half in length and twice in number the conductive members of the longitudinal structure 1 adjacent to the central side are electrically connected together via the resistor 2 to constitute each longitudinal structure 1. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a disturbing electromagnetic wave reducing device used for countermeasures against electromagnetic noise and an electronic apparatus including the same.

  As electronic devices have higher functionality and higher clocks in recent years, obstacles due to electromagnetic waves generated from electronic devices have become a problem. In particular, in an image reading unit such as a copying machine, the clock frequency is high for high image quality, and leakage electromagnetic wave noise has become an important problem.

  Therefore, Patent Document 1 proposes an electromagnetic wave absorber that absorbs magnetic field energy by module heat in which a metal plate is brought into close contact with a ferromagnetic material and an induced current caused by a magnetic field collected in the ferromagnetic material is generated in the metal plate. .

  However, since the relative permeability of a ferromagnetic material generally decreases in a high frequency region, it is unclear to what extent it is effective as a ferromagnetic material at a frequency of several hundred MHz.

  Further, in Patent Document 2, the slit is arranged by paying attention to the current distribution in the resonance mode of the casing, but the slit absorbs electromagnetic waves by arranging the slit so as not to disturb the original casing shielding performance. Not what you want.

Patent Document 3 discloses that an electric resistor is attached to a plate having an equiangular spiral structure to absorb electric field energy in the housing.
JP-A-11-261280 JP 2003-115961 A JP 2008-47839 A

  However, although the invention described in Patent Document 3 is effective for circularly polarized waves, linearly polarized electromagnetic wave noise emitted from a longitudinal structure such as a harness cannot be efficiently absorbed.

  The present invention has been made in view of such problems, and an object of the present invention is to provide an interference electromagnetic wave reduction device that is an electronic device that exhibits an electromagnetic wave reduction effect in a wide band with respect to linearly polarized waves.

  In order to achieve the above object, as a first aspect, the present invention provides a disturbance electromagnetic wave reduction device for reducing electromagnetic interference emitted from an electronic device, and is a longitudinal direction of an electromagnetic noise source that is the source of the electromagnetic interference A first longitudinal structure formed by electrically connecting two conductive members arranged in the same direction via a resistor, and the first longitudinal structure around the first longitudinal structure. And at least a pair of second longitudinal structures arranged symmetrically in the short direction of the structure, each of the second longitudinal structures being adjacent to the center side of the first or second longitudinal structure The present invention provides an interference electromagnetic wave reducing device characterized in that a conductive member having a length half that of the conductive member is electrically connected through a resistor, twice as many as the conductive member. is there.

  In the first aspect of the present invention, when the output impedance of the longitudinal structure is Z1, the output resistance is R, the reactance is X, and Z1 = R + jX (j is an imaginary unit), the impedance of the resistor is Z2 = R -JX is preferable. The conductive member is preferably a metal. The conductive member is formed on the basis of a thin film, and the first and second longitudinal structures are preferably provided on the insulating thin film layer. In addition, the insulating thin film layer includes the first thin film layer. It is more preferable that an adhesive layer is provided on the surface opposite to the side on which the second longitudinal structure is provided.

  Moreover, in order to achieve the said objective, this invention provides the electronic device characterized by the interference electromagnetic wave reduction apparatus which concerns on the said 1st aspect of the said invention being installed in the housing | casing as a 2nd aspect. Is.

  ADVANTAGE OF THE INVENTION According to this invention, the electromagnetic wave reduction apparatus which shows the electromagnetic wave reduction effect with respect to a linear polarization in a wide band, and an electronic device provided with the same can be provided.

  A preferred embodiment of the present invention will be described. In FIG. 1, the external appearance of the interference electromagnetic wave reduction apparatus which concerns on this embodiment is shown. The interference electromagnetic wave reducing device has a longitudinal structure 1 having a conductive member and a resistor 2, and is installed in a casing 4 of an electronic device provided with a half-wave dipole antenna 3 simulating a harness as a noise source. .

  2 and 3, the dimensions in the X and Y directions of the conductive longitudinal structure group are a1 and b1. In addition, the dimension in the Y direction of the half-wave dipole antenna 3 simulating a harness of an electronic device that is a noise source is b2, and the distance to the conductive longitudinal structure group is d. In addition, the dimensions in the X, Y, and Z directions of the housing incorporating the electronic device are a3, b3, and c3.

  The principle that the radiated electromagnetic wave is reduced will be described with reference to FIG. An example is a structure in which a harness as a radiation source is inside the housing, but a scanner having a wide opening is assumed as the housing, and the housing is hardly affected. In FIG. 4A, from the relationship of the sensitivity of the half-wave dipole antenna 3, it is preferable that the half-wave dipole antenna 3 and the conductive longitudinal structure group 1 are parallel.

  In the longitudinal structure group 1, a half-wave voltage distribution is generated as in the voltage distribution 7 with the length of the dipole antenna being a half wavelength, and a voltage is generated in the resistor 2. At that time, when a current flows through the resistor 2, Joule heat is generated, and electromagnetic noise can be reduced.

  However, when the frequency is increased, the voltage distribution 7 becomes as shown in FIG. 4B, and the voltage applied to the resistor 2 becomes zero, so that the electromagnetic wave noise reduction effect is reduced.

  In this case, as shown in FIG. 4 (c), a longitudinal structure 1d is installed on both sides of the longitudinal structure 1, and each of the longitudinal structures 1d has three resistors 2d, and the longitudinal structure has 4 etc. Arrange to divide. Thereby, since a resistor can be placed at a high voltage location in the voltage distribution 7, an electromagnetic noise reduction effect can be realized even at a high frequency.

In addition, the longitudinal structure group may be sequentially installed, the number of resistors may be 6, 14, 30, 62, and the number of conductive members may be 8, 16, 32, and 64. The number y1 of resistors is represented by the following formula (1), and the number y2 of conductive members is represented by the following formula (2). And the reduction effect in a wide band is realizable by putting a some longitudinal structure.
y1 = −2 + 8 × 2 ^(k−1) (k = 1, 2, 3,...) (1)
y2 = 8 × 2 ^(k−1) (k = 1, 2, 3,...) (2)

Next, the effect obtained by the casing having the above configuration is verified by numerical simulation.
First, when the longitudinal structure group 1 made up of the resistor 2 and the conductive member is placed on the noise source built in the housing shown in FIG. 1 (CASE 1), it is built in the housing as shown in FIG. The radiated electric field strength is calculated for the case of only the noise source (CASE 2).
1 and 5 are already shown in FIGS. 2 and 3. FIG. Here, a1 = 100 mm, b1 = 400 mm, b2 = 390 mm, a3 = 500 mm, b3 = 400 mm, c3 = 60 mm, and d = 40 mm. The resistance value of the resistor 2 is 50Ω. Here, the radiated magnetic field is evaluated by simulation using a calculation analysis method called FDTD method (Finite Difference Time Domain method). In this analysis, the analysis space is divided into a grid and the Maxwell equation is subtracted and solved in the time domain. Specifically, a Gaussian pulse including a wide range of frequency components is input to the input end of the dipole antenna, which is the input point, and all lattice points in the time domain on the xy plane 55 mm in the z direction from the resistor. Capture magnetic field information. The magnetic field information is frequency-converted to obtain average magnetic field information on the xy plane in the frequency domain.

FIG. 6 shows the radiated magnetic field intensity in the case of CASE 1 shown in FIG. 1 and CASE 2 shown in FIG. For example, CASE2 is 5.28e ^-5 [A / m] and CASE1 is 1.28e ^-5 [A / m] with a frequency of 374 MHz. It can be confirmed that a reduction effect is obtained at a frequency of 270 MHz or higher.

  In this way, by placing half-wave dipole antennas of different lengths adjacent to each other, electromagnetic noise can be reduced over a wide range of frequencies against linearly polarized electromagnetic noise from a longitudinal structure such as a harness. It becomes possible.

  When the output impedance of the conductive member is Z1, the output resistance is R, the reactance is X, the imaginary number is j, and Z1 = R + jX, the impedance of the resistor is preferably Z2 = R−jX. In this way, as shown in Saji Manabu, “Electric Circuit A”, Ohm Co., p75, power is most effectively consumed by the resistor from the maximum power supply theorem. Thereby, the effect of reducing electromagnetic wave noise can be obtained more remarkably. That is, electromagnetic wave noise can be further reduced by matching the output impedance between the resistor and the half-wave dipole antenna.

  The conductive member constituting the longitudinal structure 1 can be any material as long as it is a material having electrical conductivity, but by making it made of metal, the material cost is higher than when using conductive plastic or the like. The same electromagnetic wave reduction effect can be realized with a cheaper configuration.

  Further, as shown in FIG. 7, a structure in which the conductive longitudinal structure group 1 and the resistor 2 are provided on the insulating layer 5 may be formed as a thin film. By setting it as such a structure, it becomes possible to implement | achieve a thin absorption structure as a whole. For example, even for a thin structure such as a document feeder of a copying machine, the absorption structure can be installed at an arbitrary place.

  Further, as shown in FIG. 8, the insulating layer 5 has a structure in which the conductive longitudinal structure group 1 and the resistor 2 are provided on one side, and the adhesive layer 6 is provided on the other side, and the insulating layer 5 and the conductive longitudinal structure are provided. The group 1 and the resistor 2 may be formed as a thin film. Generally, in the case of a copying machine, it is covered with an exterior plastic so as to surround a metal frame. When electromagnetic wave noise is generated from the harness, it is possible to easily install the interference radio wave reducing device using the adhesive layer 6 inside the exterior plastic at that location.

  In addition, the said embodiment is an example of suitable implementation of this invention, and various deformation | transformation are possible for this invention, without being limited to this.

It is a figure which shows the structure of the electronic device with which the interference electromagnetic wave reduction apparatus which concerns on suitable embodiment of this invention was installed. It is a figure which shows the structure of the electronic device with which the interference electromagnetic wave reduction apparatus which concerns on suitable embodiment of this invention was installed. It is a figure which shows the structure of the electronic device with which the interference electromagnetic wave reduction apparatus which concerns on suitable embodiment of this invention was installed. It is a figure which shows the principle by which a radiation electromagnetic wave is reduced. It is a figure which shows the structure of the electronic device in which the interference electromagnetic wave reduction apparatus is not installed. It is a figure which shows a radiation magnetic field intensity | strength. It is a figure which shows the interference electromagnetic wave reduction apparatus of the structure which provided the electroconductive longitudinal structure group and the resistor on the insulating layer. It is a figure which shows the interference electromagnetic wave reduction apparatus of the structure which provided the electroconductive longitudinal structure group and the resistor in one side of the insulating layer, and provided the adhesion layer in the other.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Longitudinal structure 2 Resistor 3 Half-wavelength dipole antenna 4 Case 5 Insulating layer 6 Adhesive layer

Claims (6)

An interference electromagnetic wave reducing apparatus for reducing electromagnetic interference emitted from electronic equipment,
A first longitudinal structure configured by electrically connecting two conductive members arranged in the same direction as the longitudinal direction of the electromagnetic noise source that is the source of the disturbing electromagnetic wave through a resistor;
Having at least a pair of second longitudinal structures disposed symmetrically in the lateral direction of the first longitudinal structure, with the first longitudinal structure as a center,
Each of the second longitudinal structures is composed of a conductive member that is half the length of the conductive member of the first or second longitudinal structure adjacent to the center side, and has twice as many resistors. A device for reducing interference electromagnetic waves, characterized in that the device is configured to be electrically connected to each other.   When the output impedance of the conductive member is Z1, the output resistance is R, the reactance is X, and Z1 = R + jX (j is an imaginary unit), the impedance of the resistor is Z2 = R-jX. The interference electromagnetic wave reducing device according to claim 1.   The interference electromagnetic wave reducing apparatus according to claim 1, wherein the conductive member is a metal.   4. The conductive member according to claim 1, wherein the conductive member is formed based on a thin film, and the first and second longitudinal structures are provided on an insulating thin film layer. The interference electromagnetic wave reducing device as described.   5. The interference electromagnetic wave reducing device according to claim 4, wherein the insulating thin film layer is provided with an adhesive layer on a surface opposite to the side on which the first and second longitudinal structures are provided.   6. An electronic apparatus, wherein the interference electromagnetic wave reducing device according to claim 1 is installed in a housing.

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