Electromagnetic wave absorbing device

Abstract

To provide an electromagnetic wave absorbing device capable of improving storage property and transportability of an electromagnetic wave absorbing sheet.SOLUTION: An electromagnetic wave absorbing device includes: an electromagnetic wave absorbing sheet capable of being wound in a roll shape; a housing that accommodates a roll of the wound electromagnetic wave absorbing sheet and rotatably supports the roll; and a support column that is provided in the housing and supports a tip of the electromagnetic wave absorbing sheet unwound from the roll. The housing is formed of a material that does not reflect electromagnetic waves or is configured to be hidden behind the unwound electromagnetic wave absorbing sheet.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present invention relates to an electromagnetic wave absorbing device using an electromagnetic wave absorbing sheet. [Background technology]

[0002] Depending on the application, electromagnetic wave absorbing materials may have a large surface area, and therefore, they are required to be rolled up and made compact for storage or transportation. To achieve this, electromagnetic wave absorbing materials are required to have a bendable structure.

[0003] Patent Document 1 discloses an electromagnetic shielding roller screen that is placed on the windows of a building to block unnecessary electromagnetic waves from the outside in order to realize high-speed, large-volume communication inside the building. In this technology, the electromagnetic shielding roller screen has a roll-up mechanism so that it can be stored and the window can be opened when the electromagnetic shielding is not required. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2006-188895 A Summary of the Invention [Problem to be solved by the invention]

[0005] Here, since there is a demand for the electromagnetic wave absorbing member to be made compact by rolling it up as described above, it is conceivable to configure it in the form of a roll screen as in Patent Document 1.

[0006] However, generally, electromagnetic shields are made of metal film and can be rolled up, whereas electromagnetic wave absorbing materials may have a two-layer structure and are not easily rolled up. In addition, electromagnetic wave absorbing materials and electromagnetic shields have different applications and modes of use.

[0007] Specifically, for example, an electromagnetic shield can prevent electromagnetic waves from entering from the outside to the inside, or vice versa. Therefore, all that is required for an electromagnetic shield is to block electromagnetic waves by reflecting them. In contrast, an electromagnetic wave absorbing material prevents both the reflection and transmission of electromagnetic waves, and literally absorbs them with the material itself. Therefore, an electromagnetic wave absorbing material has a more complex and large-scale structure than an electromagnetic shield.

[0008] Therefore, there is a problem in that it is difficult to apply the structure described in Patent Document 1 as it is to an electromagnetic wave absorbing member.

[0009] The present invention has been made in consideration of the above-mentioned problems, and an object of the present invention is to provide an electromagnetic wave absorbing device that can improve the storability and transportability of an electromagnetic wave absorbing sheet. [Means for solving the problem]

[0010] The electromagnetic wave absorbing device of the present invention comprises an electromagnetic wave absorbing sheet that can be wound into a roll, a housing that houses the roll of the electromagnetic wave absorbing sheet and rotatably supports the roll, and a support pillar provided in the housing that supports the tip of the electromagnetic wave absorbing sheet unwound from the roll, and is characterized in that the housing is formed of a material that does not reflect electromagnetic waves or is configured to be hidden behind the unwound electromagnetic wave absorbing sheet. Effect of the Invention

[0011] According to the present invention, it is possible to improve the storability and transportability of an electromagnetic wave absorbing sheet. [Brief description of the drawings]

[0012] [Figure 1] FIG. 1 is a diagram showing a usage form of an electromagnetic wave absorbing device according to a first embodiment of the present invention. [Diagram 2] FIG. 1 is a diagram showing the overall configuration of an electromagnetic wave absorbing device. [Diagram 3] 4 is a side cross-sectional view of the housing, showing the configuration of a portion where an electromagnetic wave absorbing sheet is pulled out from the housing. FIG. [Figure 4] FIG. 2 is a cross-sectional view illustrating an electromagnetic wave absorbing sheet. [Diagram 5] FIG. 4 is a top view showing an example of an electromagnetic wave absorbing layer. [Figure 6] FIG. 4 is a diagram showing the overall configuration of an electromagnetic wave absorbing device according to a second embodiment. [Figure 7] FIG. 13 is a diagram showing the configuration of a housing of a second embodiment. [Figure 8] FIG. 13 is a diagram showing the overall configuration of an electromagnetic wave absorbing device according to a third embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0013] Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.

[0014] (First embodiment) FIG. 1 is a diagram showing a usage form of an electromagnetic wave absorbing device 100 according to a first embodiment of the present invention.

[0015] In recent years, advanced driver-assistance systems (ADAS) have been developed in the field of automobiles for the purpose of collision prevention, etc. In such systems, the radar and control devices mounted on the vehicle need to be adjusted and calibrated periodically to ensure that they always operate normally. This adjustment and calibration work is called an aiming test.

[0016] In an aiming test, as shown in FIG. 1, electromagnetic waves emitted from an automobile 102 and reflected by a target 104 are received by a receiver, and based on the received signal, it is determined whether the radar and control device of the automobile 102 are functioning normally.

[0017] In this case, if there are electromagnetic wave reflecting objects 106 other than the target 104 around the automobile 102, the electromagnetic waves reflected therefrom become noise, and the reflected signal from the target 104 cannot be accurately detected. As a result, the inspection cannot be performed normally. Basically, it is desirable to perform the aiming inspection in a large space where there are absolutely no electromagnetic wave reflecting objects around the automobile 102, but in a typical automobile repair shop or the like, it may not be possible to secure a work area of ​​such a size.

[0018] Therefore, one or more electromagnetic wave absorbing devices 100 of this embodiment are placed at appropriate locations between the automobile 102 and the electromagnetic wave reflecting object 106 to absorb electromagnetic waves radiated in directions other than the target 104, thereby preventing the device from being affected by the electromagnetic wave reflecting object 106 behind it.

[0019] Next, Fig. 2 is a diagram showing the overall configuration of the electromagnetic wave absorbing device 100 of this embodiment. Fig. 2(a) shows a side cross-sectional view of the electromagnetic wave absorbing device 100, Fig. 2(b) shows a partial cross-sectional view taken along line AA in Fig. 2(a) when the electromagnetic wave absorbing device 100 is viewed from the back, and Fig. 2(c) is a front view of the electromagnetic wave absorbing device 100.

[0020] The electromagnetic wave absorbing device 100 has the form of a partition, and is installed between a target 104 and an electromagnetic wave reflecting object 106 as shown in Fig. 1. Usually, the electromagnetic wave absorbing device 100 is installed so that a surface B of an electromagnetic wave absorbing sheet 203 described later as shown in Fig. 2(a) faces the automobile 102. The size of the electromagnetic wave absorbing device 100 is not particularly limited, but the height is usually 0.1 m to 3.0 m, preferably 0.4 m to 2.2 m, and more preferably 0.8 m to 2.0 m. Meanwhile, the width is usually 0.1 m to 2.0 m, preferably 0.4 m to 1.7 m, and more preferably 0.8 m to 1.2 m.

[0021] In FIG. 2, the electromagnetic wave absorbing device 100 is installed on a floor surface or the like and comprises a housing 201 which forms the base of the electromagnetic wave absorbing device 100, an electromagnetic wave absorbing sheet 203 wound in a roll which is contained within the housing 201, and a support 205 which supports the electromagnetic wave absorbing sheet 203 in an upright position.

[0022] The housing 201 is formed to have a rectangular parallelepiped space capable of accommodating the electromagnetic wave absorbing sheet 203 wound in a roll. Inside the housing 201, a shaft member 207 for rotatably supporting the electromagnetic wave absorbing sheet 203 wound in a roll is disposed. The shaft member 207 is rotatably supported relative to the housing 201 by a bearing 209 such as a bearing. Inside the shaft member 207, a torsion spring (not shown) is built in to bias the shaft member 207 so as to rotate the electromagnetic wave absorbing sheet 203 in a direction in which the electromagnetic wave absorbing sheet 203 is wound up, and the electromagnetic wave absorbing sheet 203 is not normally in an undrawn state as shown in FIG. 2 but is in a state in which it is wound up inside the housing 201 due to the biasing force of the torsion spring.

[0023] The housing 201 is formed with a rectangular opening 201a for pulling out the electromagnetic wave absorbing sheet 203 to the outside of the housing 201. The electromagnetic wave absorbing sheet 203 is held in a state pulled out to the outside of the housing 201 through this opening 201a, and from this state, the user pulls up the tip of the electromagnetic wave absorbing sheet 203 to unfold it into a usable state as shown in Fig. 2. That is, the electromagnetic wave absorbing device 100 according to this embodiment is a free-standing type. Therefore, there is a high degree of freedom in the installation location compared to a type in which the housing is installed in a high place such as a ceiling or a wall and the sheet is pulled down from the housing to unfold it.

[0024] 2(c), when the side B of the electromagnetic wave absorbing sheet 203 faces the automobile 102, the housing 201 has an area 201b (a hatched area) that protrudes from the electromagnetic wave absorbing sheet 203 when viewed from the front. For example, if the area 201b is made of a metal material that reflects electromagnetic waves, the electromagnetic waves emitted from the automobile 102 are reflected by the area 201b, causing noise. For this reason, it is preferable that the housing 201 is made of a nonmetallic material that does not reflect electromagnetic waves, or that a so-called magnetic type electromagnetic wave absorbing layer, for example, made of resin with ferromagnetic metal powder dispersed therein, is formed on the surface of the housing 201. Even if the housing 201 is made of a metal material, by lowering the position of the opening 201a of the housing 201 as much as possible, most of the housing 201 is hidden by the electromagnetic wave absorbing sheet 203, so that the noise caused by the reflection of the electromagnetic waves at the housing 201 can be minimized. As for the hidden area, for example, it is preferable that 90% or more of the area of ​​the front side of the housing 201 is hidden behind the electromagnetic wave absorbing sheet 203, and it is more preferable that 95% or more is hidden behind the electromagnetic wave absorbing sheet 203.

[0025] Support columns 205 are erected on both the left and right sides of the upper part of housing 201. Locking members 205a made of magnets are arranged on the tips of support columns 205, and are configured to support the tip of electromagnetic wave absorbing sheet 203 by the attraction force of locking members 205a. Correspondingly, attraction members 203a made of a magnetic material (metal such as iron) or a magnet, which are attracted by locking members 205a, are also attached to the tip of electromagnetic wave absorbing sheet 203.

[0026] Here, if attraction member 203a is also made of an iron plate or the like, it will reflect electromagnetic waves and become a source of noise, so attraction member 203a is desirably configured to cover the iron plate, magnet, or the like with a nonmetallic material that does not reflect electromagnetic waves. Note that, here, it has been described that a magnet is placed at the tip of support 205, and a magnetic body is placed at the tip of electromagnetic wave absorbing sheet 203. However, the present invention is not limited to this, and a magnet may be placed at the tip of electromagnetic absorption sheet 203 and a magnetic body may be placed at the tip of support 205, or magnets may be placed on both.

[0027] Furthermore, when the use of the electromagnetic wave absorbing device 100 is finished and the electromagnetic wave absorbing sheet 203 is rolled up inside the housing 201, the adsorption member 203a gets caught at the entrance of the opening 201a, thereby preventing the electromagnetic wave absorbing sheet 203 from being completely drawn into the housing 201.

[0028] The support 205 is configured to be extendable (telescopic), and Fig. 2 shows a state in which it is extended and the electromagnetic wave absorbing device 100 can be used. From this state, the user can retract the support 205, and when putting away or transporting the electromagnetic wave absorbing device 100, the support 205 can be reduced in size to the height indicated by D in Fig. 2(b). The retracted support 205 may be structured so that it can be tilted toward the housing 201 and fixed to the housing 201.

[0029] When using the electromagnetic wave absorbing device 100 configured as above, the user carries and installs the electromagnetic wave absorbing device 100 to a place where electromagnetic waves are to be blocked. Then, the support 205 is pulled up and extended, and the tip of the electromagnetic wave absorbing sheet 203 is pulled up, so that the adsorption member 203a at the tip is adsorbed to the locking member 205a of the support 205. By such an operation, the electromagnetic wave absorbing device 100 is ready for use. On the other hand, when putting away or transporting the electromagnetic wave absorbing device 100, the user removes the adsorption member 203a at the tip of the electromagnetic wave absorbing sheet 203 from the locking member 205a of the support 205, and winds up the electromagnetic wave adsorption sheet 203 inside the housing 201 by the biasing force of the torsion spring. After that, the support 205 is retracted to make it smaller. By such an operation, the electromagnetic wave absorbing device 100 is ready for portability.

[0030] In the above description, an example is given in which an extendable support is used, but the present invention is not limited to this, and the type of support is not important as long as it is configured to support the electromagnetic wave absorbing sheet.

[0031] Next, FIG. 3 is a side cross-sectional view of the housing, showing the configuration of a portion where electromagnetic wave absorbing sheet 203 is pulled out from housing 201. As shown in FIG.

[0032] In the above Fig. 2(a) and its description, it has been described that the electromagnetic wave absorbing sheet 203 is pulled out substantially horizontally from the housing 201 and then bent upward as shown in Fig. 3. In this case, as shown in Fig. 3(a), the housing 201 is formed with a guide portion 201c that guides the electromagnetic wave absorbing sheet substantially horizontally.

[0033] However, when the electromagnetic wave absorbing sheet 203 is pulled out horizontally in this manner, the curvature of the bent portion 203b of the electromagnetic wave absorbing sheet 203 becomes large, and it is considered that the electromagnetic wave absorbing sheet 203 may become curled. If the electromagnetic wave absorbing sheet 203 becomes curled, the flatness of the electromagnetic wave absorbing sheet 203 in the used state may deteriorate, and the electromagnetic wave absorption characteristics may deteriorate. Furthermore, when the electromagnetic wave absorbing sheet 203 is wound up around the housing 201, it may not be wound up smoothly.

[0034] Therefore, in a modification of this embodiment, the housing 201 is provided with guide portions 201d having a gentle curvature that bend the electromagnetic wave absorbing sheet 203 gently obliquely upward. By providing such guide portions 201d, the electromagnetic wave absorbing sheet 203 is less likely to develop a curling habit, and the electromagnetic wave absorbing sheet 203 can be made more flat when pulled out upward. Furthermore, the electromagnetic wave absorbing sheet 203 can be smoothly rolled up into the housing 201 when it is stored.

[0035] Next, a description will be given of the configuration of the electromagnetic wave absorbing sheet 203. The electromagnetic wave absorbing sheet 203 in this embodiment is configured so as to be easily rolled up so that it can be used in the electromagnetic wave absorbing device 100.

[0036] FIG. 4 is a cross-sectional view along the thickness direction, which diagrammatically shows the electromagnetic wave absorbing sheet 203 in this embodiment.

[0037] 4, the electromagnetic wave absorbing sheet 203 of this embodiment has a resistive layer 20, a spacer layer 30, and a reflective layer 40. Moreover, the resistive layer 20, the spacer layer 30, and the reflective layer 40 are laminated in this order.

[0038] The reflective layer 40 is disposed on the other surface (rear surface) 20b side of the resistive layer 20. The spacer layer 30 is disposed between the resistive layer 20 and the reflective layer 40. That is, the resistive layer 20 and the reflective layer 40 are laminated with the spacer layer 30 interposed therebetween.

[0039] The resistive layer 20 may be a single layer, or may include a substrate 21 and a conductive pattern 22 formed on the substrate 21 as shown in FIG.

[0040] When the resistive layer 20 is a single layer, the resistive layer 20 is made of the same material as the conductive pattern 22 described below.

[0041] In the electromagnetic wave absorbing sheet 203 of this embodiment, a plurality of slits 50 are formed from the outermost surface of the resistive layer 20 (one surface (upper surface) 21a of the substrate 21 in FIG. 4) in the thickness direction of the resistive layer 20 and the spacer layer 30. A laminate 60 consisting of the resistive layer 20 and the spacer layer 30 is divided into a plurality of regions (regions 60A, 60B, and 60C in FIG. 4) via the plurality of slits 50. The slits 50 may be parallel to the thickness direction of the resistive layer 20 and the spacer layer 30, or the slit width may be narrowed toward the side end of the reflective layer 40 in the spacer layer 30.

[0042] In the electromagnetic wave absorbing sheet 203 of this embodiment, the width of the plurality of slits 50, i.e., the width W0 of the slits 50 on the outermost surface of the resistance layer 20 (one surface 21a of the substrate 21) in Fig. 1, is less than 10 mm, preferably 5 mm or less, and more preferably 2 mm or less. When the width W0 is equal to or less than the above upper limit, the resistance layer 20 is likely to have sufficient transmission characteristics for the intended electromagnetic wave.

[0043] In the electromagnetic wave absorbing sheet 203 of the present embodiment, it is preferable that adjacent spacer layers 30 are at least partially connected to each other at the ends of the plurality of slits 50 on the reflective layer 40 side. In other words, it is preferable that the reflective layer 40 is not exposed at the ends of the plurality of slits 50 on the reflective layer 40 side. This makes it possible to provide the obtained electromagnetic wave absorbing sheet 203 with excellent durability against repeated winding.

[0044] In the electromagnetic wave absorbing sheet 203 of this embodiment, in a plan view of the electromagnetic wave absorbing sheet 203, the interval d0 between the plurality of slits 50 is preferably 0.1 mm or more and 30 cm or less, more preferably 1 mm or more and 100 mm or less, and even more preferably 3 mm or more and 20 mm or less. When the interval d0 is equal to or more than the above lower limit, the frequency of dividing the laminate 60 by the slits 50 decreases, and the transmission characteristics of the resistance layer 20 are easily maintained. When the interval d0 is equal to or less than the above upper limit, the winding property of the electromagnetic wave absorbing sheet 203 is improved, and the storage size of the electromagnetic wave absorbing sheet 203 is reduced. Note that the interval d0 is the distance of the center line C passing through the slits 50 in parallel with the thickness direction of the resistance layer 20 and the spacer layer 30. Note that in FIG. 4, the direction indicated by the arrow A is the outer periphery side of the roll around which the electromagnetic wave absorbing sheet 203 is wound, and the direction indicated by the arrow B is the inner periphery side of the roll. That is, the electromagnetic wave absorbing sheet 203 is arranged so that the electromagnetic wave is incident on the surface on which the slits 50 are formed.

[0045] The slits 50 are formed by cutting the resistance layer 20 and the spacer layer 30 in the thickness direction with a cutter or the like. When the electromagnetic wave absorbing sheet 203 is spread out in a planar state (unwound state), the physical gaps (gaps caused by the slits 50) in the electromagnetic wave absorbing sheet 203 are minimized, and therefore the reflection of electromagnetic waves from the reflective layer 40 is also minimized. Therefore, the electromagnetic wave absorbing sheet 203 of this embodiment has the best electromagnetic wave absorption properties when it is unrolled and used in a planar state after being rolled up. With the above-mentioned configuration, the winding property of the electromagnetic wave absorbing sheet 203 can be improved.

[0046] The electromagnetic wave absorbing sheet 203 of this embodiment has a bending stiffness of 1.0×10 -4 Pa mm 4 More than 2250Pa mm 4 Less than or equal to 1.7×10 is preferable. -3 Pa mm 4 More than 1040Pa mm 4 Less than 6.7×10 is more preferable. -3 Pa mm 4 More than 390Pa mm 4 The following is even more preferred:

[0047] The bending rigidity of the electromagnetic wave absorbing sheet 203 is determined by the product of the Young's modulus and the second moment of area of ​​the reflective layer 40. In this specification, the second moment of area is calculated for a rectangular model with a unit width of 20 cm.

[0048] Furthermore, even without providing the slits 50, the spacer layer 30 can be made thin by increasing its dielectric constant, and thus the electromagnetic wave absorbing sheet 203 that is easy to roll can be obtained. For example, the relative dielectric constant of the spacer layer 30 can be adjusted to 5 to 15 by adding a high dielectric material such as titanium oxide, barium titanate, or strontium titanate to the spacer layer 30. In this case, the thickness of the spacer layer is usually 1.5 mm or less, preferably 1.0 mm or less, and more preferably 0.4 mm or less. When such a thin spacer layer 30 is used, the total thickness of the electromagnetic wave absorbing sheet 203 is usually 2 mm or less, preferably 1 mm or less, and more preferably 0.5 mm or less, which is suitable for rolling. The lower limit of the total thickness is not particularly restricted, but is about 0.1 mm or more in consideration of electromagnetic wave absorption. Even when such a highly dielectric spacer layer 30 is used, the slits 50 similar to those described above may be provided. In that case, the rolling property of the electromagnetic wave absorbing sheet 203 becomes even better.

[0049] The resistive layer 20 is made of a frequency selective surface (FSS). A frequency selective surface is a surface that can block or transmit only electromagnetic waves of a specific frequency by forming a continuous structure of a shape smaller than the wavelength using a conductive material or the like.

[0050] Fig. 5 is a top view showing an example of a resistance layer in this embodiment. As shown in Fig. 5, the resistance layer 20 has a flat base material 21 and a conductor pattern 22 formed on one surface 21a of the base material 21.

[0051] As described above, with the configuration as shown in Figs. 4 and 5, the electromagnetic wave absorbing sheet 203 of this embodiment can be easily rolled up.

[0052] As described above, according to this embodiment, the roll-up ability of the electromagnetic wave absorbing sheet can be improved, and further, if the casing is made of a material that does not reflect electromagnetic waves, or if it is made of a material that reflects electromagnetic waves, the storability and transportability of the electromagnetic wave absorbing sheet can be improved by making the casing hidden by the electromagnetic wave absorbing sheet.

[0053] Second embodiment In the first embodiment, an example has been described in which the housing 201 covers the entire width of the electromagnetic wave absorbing sheet 203. In contrast, in the present embodiment, an example will be described in which the horizontal width of the housing 201 is narrower than the width of the electromagnetic wave absorbing sheet 203, and most of the housing 201 is hidden behind the electromagnetic wave absorbing sheet 203.

[0054] Fig. 6 is a diagram showing the overall configuration of an electromagnetic wave absorbing device 600 of this embodiment. Fig. 6(a) shows a diagram of the electromagnetic wave absorbing device 600 seen from the back, and Fig. 6(b) shows a diagram of the electromagnetic wave absorbing device 600 seen from the front. Fig. 7 shows the configuration of a housing 601, with Fig. 7(a) showing a top view of the housing 601, Fig. 7(b) showing a back view of the housing 601, and Fig. 7(c) showing a side view of the housing 601.

[0055] The electromagnetic wave absorbing device 600 has the form of a partition as shown in Fig. 6, and is used by being placed between the target 104 and the electromagnetic wave reflecting object 106 as shown in Fig. 1. Usually, it is placed so that the C surface of the electromagnetic wave absorbing sheet 203 described later as shown in Fig. 6(b) faces the automobile 102. The size of the electromagnetic wave absorbing device 600 is the same as that of the first embodiment.

[0056] In FIG. 6, the electromagnetic wave absorbing device 600 is installed on a floor surface or the like and comprises a housing 601 which forms the base of the electromagnetic wave absorbing device 600, an electromagnetic wave absorbing sheet 203 wound in a roll whose central portion is contained in the housing 601, and a support 605 which supports the electromagnetic wave absorbing sheet 203 in an upright position.

[0057] The housing 601 is formed to have a rectangular parallelepiped space capable of accommodating the central portion of the electromagnetic wave absorbing sheet 203 wound in a roll shape. As shown in FIG. 7(a), arm parts 601c that are U-shaped when viewed from above are formed on both sides of the housing 601. Between the U-shaped arm parts 601c, an axis member 607 for rotatably supporting the electromagnetic wave absorbing sheet 203 wound in a roll shape is disposed. The axis member 607 is rotatably supported relative to the housing 601 by a bearing 609 such as a bearing. A torsion spring (not shown) is built in the inside of the axis member 607 to bias the axis member 607 so as to rotate the electromagnetic wave absorbing sheet 203 in a direction in which the electromagnetic wave absorbing sheet 203 is wound up. In a normal state, the electromagnetic wave absorbing sheet 203 is not in a pulled-out state as shown in FIG. 6 but is in a rolled-up state within the housing 601 by the biasing force of the torsion spring.

[0058] A groove-shaped opening 601a is formed in the housing 601 for drawing out the electromagnetic wave absorbing sheet 203 to the outside of the housing 601. The electromagnetic wave absorbing sheet 203 is held in a state drawn out to the outside of the housing 601 through this opening 601a, and from this state, the user pulls up the tip of the electromagnetic wave absorbing sheet 203, unfolding it into a usable state as shown in FIG.

[0059] Moreover, the width of the housing 601 is smaller than the width of the electromagnetic wave absorbing sheet 203, and most of the housing 601 is hidden behind the electromagnetic wave absorbing sheet 203. Therefore, even if the housing 601 is made of metal, the electromagnetic waves do not reach the metal surface directly, and it does not become a source of noise. As shown by hatching in FIG. 6(b), a small area 601b of the housing 601 may exist as a part not hidden by the electromagnetic wave absorbing sheet 203, but since this area is small, it is possible to minimize the reflection of electromagnetic waves that become noise. Alternatively, the area 601b not hidden by the electromagnetic wave absorbing sheet 203 may be formed of a nonmetallic material that does not reflect electromagnetic waves. Also, the area of ​​the area 601b may be made as small as possible by positioning the opening 601a of the housing 601 as low as possible. As in the first embodiment, in this embodiment too, it is desirable that, for example, 90% or more of the area of ​​the front side of the housing 601 is hidden behind the electromagnetic wave absorbing sheet 203, and it is even more desirable that 95% or more is hidden behind the electromagnetic wave absorbing sheet 203.

[0060] Support columns 605 are erected on both the left and right sides of the upper part of housing 601. Locking members 605a made of magnets are arranged on the tips of support columns 605, and are configured to support the tip of electromagnetic wave absorbing sheet 203 by the attraction force of locking members 605a. Correspondingly, an attraction member 603a made of a magnetic material (metal such as iron) or a magnet is attached to the tip of electromagnetic wave absorbing sheet 203, which is attracted by locking members 605a.

[0061] Here, if the attraction member 603a is also made of an iron plate or the like, it will reflect electromagnetic waves and become a source of noise, so it is desirable that the attraction member 603a is configured so that the iron plate or magnet is covered with a non-metallic material that does not reflect electromagnetic waves.

[0062] Furthermore, when the use of the electromagnetic wave absorbing device 600 is finished and the electromagnetic wave absorbing sheet 203 is rolled up inside the housing 601, the adsorption member 603a gets caught at the entrance of the opening 601a, thereby preventing the electromagnetic wave absorbing sheet 603 from being completely drawn into the housing 601.

[0063] 6 shows the support pole 605 in an extended state in which the electromagnetic wave absorbing device 600 can be used. From this state, the user can retract the support pole 605, and when putting away or transporting the electromagnetic wave absorbing device 600, the support pole 605 can be retracted to make it smaller.

[0064] As described above, according to this embodiment, by making the housing almost completely hidden by the electromagnetic wave absorbing sheet, in addition to the effects of the first embodiment, the effect of increasing the freedom in the material used for the housing is obtained.

[0065] (Third embodiment) Next, a third embodiment of the present invention will be described. Since the third embodiment has many common parts with the first embodiment, the same parts are denoted by the same reference numerals as in the first embodiment and the description thereof will be omitted.

[0066] Fig. 8 is a diagram showing the overall configuration of an electromagnetic wave absorbing device 800 of a third embodiment. Fig. 8(a) shows a side cross-sectional view of the electromagnetic wave absorbing device 800, Fig. 8(b) shows a partial cross-sectional view taken along line DD in Fig. 8(a) when the electromagnetic wave absorbing device 800 is viewed from the rear, and Fig. 8(c) is a front view of the electromagnetic wave absorbing device 800.

[0067] In FIG. 8, the electromagnetic wave absorbing device 800 is installed on a floor surface or the like and comprises a housing 201 which forms the base of the electromagnetic wave absorbing device 800, a rolled-up electromagnetic wave absorbing sheet 203 housed within the housing 201, and a foldable support 808 which supports the electromagnetic wave absorbing sheet 203 in an upright position.

[0068] A shaft member 207 for rotatably supporting the rolled electromagnetic wave absorbing sheet 203 is disposed inside the housing 201. As in the first embodiment, in a normal state, the electromagnetic wave absorbing sheet 203 is not in a pulled-out state as shown in Fig. 8, but in a wound state inside the housing 201 due to the biasing force of a torsion spring in the shaft member 207.

[0069] The housing 201 is formed with a rectangular opening 201a for drawing out the electromagnetic wave absorbing sheet 203 to the outside of the housing 201. In this embodiment, unlike the first embodiment, the opening 201a opens not in the front surface of the housing 201 but in the center of the top surface. When in use, the electromagnetic wave absorbing sheet 203 is drawn upward from this opening 201a.

[0070] The aforementioned support 808 is disposed on the upper surface of the housing 201. The support 808 has two arms 802a and 802b that rotate around fulcrums 804a and 804b disposed on the housing 201, and two arms 802c and 802d that are disposed at the tips of these arms and further rotate around fulcrums 805a and 805b. The tips of the two arms 802c and 802d are connected to a support member 203c disposed at the tip of the electromagnetic wave absorbing sheet 203 via a connection part 806 so that these arms can rotate.

[0071] The arms 802a to 802d constituting the support 808 can be extended and retracted in a pantograph-like manner as shown by arrows E and F in FIG. 8(b) by the above-mentioned configuration. The arms 802a to 802d are configured to be able to be stopped at a plurality of height positions by a locking mechanism (not shown). When the arms 802a to 802d are locked at the highest position, they are held in an extended use state as shown in FIG. 8(b). When the support member 203c is further raised from this state, the lock is released and the arms 802a to 802d can be folded. When the arms 802a to 802d are locked in the folded state by a locking member (not shown), the support 808 can be held in a contracted state. As described above, the support 808 is configured to be able to be locked at a plurality of height positions, so that it is possible to use it at an intermediate height, not just the maximum height as shown in FIG.

[0072] When using the electromagnetic wave absorbing device 800 configured as above, the user carries and installs the electromagnetic wave absorbing device 800 at a place where electromagnetic waves are to be blocked. Then, the user releases the locking member that locks the support 808, pulls up the support member 203c at the tip of the electromagnetic wave absorbing sheet 203, makes the support 808 stand upright, and locks it at that position with the above-mentioned locking mechanism. By such operations, the electromagnetic wave absorbing device 800 is ready for use. On the other hand, when putting away or transporting the electromagnetic wave absorbing device 800, the user pulls up the support member 203c one more step to release the lock, and shrinks the support 808 so that the electromagnetic wave absorbing sheet 203 is completely wound up inside the housing 201. Then, the user locks the support 808 in the shrunken state with a locking member (not shown). By such operations, the electromagnetic wave absorbing device 800 is ready for portability.

[0073] In this embodiment, as shown in FIG. 8(c), when the device is viewed from the front, the housing 201 is not hidden behind the electromagnetic wave absorbing sheet 203. Therefore, in this embodiment, the housing 201 is formed of a non-metallic material that does not reflect electromagnetic waves so that the housing 201 does not reflect electromagnetic waves. Alternatively, a magnetic type electromagnetic wave absorbing layer, for example, made of resin with ferromagnetic metal powder dispersed therein, may be formed on the surface of the housing 201. Similarly, the support member 203c at the tip of the electromagnetic wave absorbing sheet 203 is also formed of a non-metallic material that does not reflect electromagnetic waves so that the support member does not reflect electromagnetic waves.

[0074] As described above, in the configuration of this embodiment as well, similarly to the first embodiment, the effect of improving the storability and transportability of the electromagnetic wave absorbing sheet can be obtained. [Explanation of symbols]

[0075] 100: electromagnetic wave absorbing device, 201: housing, 203: electromagnetic wave absorbing sheet, 205: support, 207: shaft member, 209: bearing

Claims

1. An electromagnetic wave absorbing sheet that can be wound into a roll; a housing that houses a roll of the electromagnetic wave absorbing sheet and rotatably supports the roll; a support provided in the housing for supporting a tip of the electromagnetic wave absorbing sheet unwound from the roll; Equipped with The electromagnetic wave absorbing device is characterized in that the housing is formed of a material that does not reflect electromagnetic waves, or is configured so as to be hidden behind the unrolled electromagnetic wave absorbing sheet.

2. 2. The electromagnetic wave absorbing device according to claim 1, wherein the support is extendable or foldable.

3. 2. The electromagnetic wave absorbing device according to claim 1, wherein the housing is placed on a floor, and the electromagnetic wave absorbing sheet is unrolled in a direction to be lifted up from the housing.

4. 2. The electromagnetic wave absorbing device according to claim 1, wherein the electromagnetic wave absorbing sheet has a resistive layer, a spacer layer, and a reflective layer in this order from the electromagnetic wave incident side.

Images