CN106659099B - Transparent electromagnetic shielding device for graphene grids and double-layer metal grids - Google Patents

Transparent electromagnetic shielding device for graphene grids and double-layer metal grids Download PDF

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CN106659099B
CN106659099B CN201510449179.3A CN201510449179A CN106659099B CN 106659099 B CN106659099 B CN 106659099B CN 201510449179 A CN201510449179 A CN 201510449179A CN 106659099 B CN106659099 B CN 106659099B
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CN106659099A (en
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谭久彬
陆振刚
王赫岩
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Harbin Institute of Technology
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Abstract

Graphene net gate/double-layer metal net gate transparent electromagnetic shielding device with two-way wave-absorbing effect belongs to the technical field of optical transparent part electromagnetic shielding, and the electromagnetic shielding device utilizes different light-transmitting and microwave shielding characteristics shown when graphene net gate films have different mesh unit opening area ratios, organically combines the low-reflection and partial-absorption microwave characteristics of the graphene net gate films and the strong electromagnetic reflection characteristic of the high-light-transmitting double-layer metal net gate, and arranges the multi-layer graphene net gate films on two sides of the double-layer metal net gate to form a multi-layer laminated structure: using a double-layer metal grid as a transparent reflecting layer, and using N layers of graphene grid films separated by transparent media as transparent absorbing layers; the structure can enable radio frequency radiation on two sides of the device to pass through the absorption layer for multiple times to be strongly absorbed, so that the bidirectional strong shielding and low reflection characteristics are realized, and visible light only penetrates through the laminated structure once and has high light transmittance; the electromagnetic shielding device solves the problem that the existing transparent electromagnetic shielding method cannot give consideration to both low electromagnetic reflection, strong electromagnetic shielding and high light transmission.

Description

Transparent electromagnetic shielding device for graphene grids and double-layer metal grids
Technical Field
The invention belongs to the field of electromagnetic shielding of optical transparent parts, and particularly relates to a graphene grid and double-layer metal grid transparent electromagnetic shielding device with a bidirectional wave absorbing effect.
Background
With the development of broadcasting, television, wireless communication technology and microwave technology, radio frequency equipment is equipped in a large number in various places where people move, the frequency spectrum range is continuously widened, and the intensity is multiplied, so that the radio frequency equipment not only causes interference to electronic equipment, but also threatens human health. The invisible electromagnetic pollution directly acts on machines or human bodies, is an invisible killer with serious harm, and becomes the fifth largest pollution following atmospheric pollution, water pollution, solid waste pollution and noise pollution. Electromagnetic shielding (including absorption and reflection) is a major measure for preventing and treating electromagnetic pollution, and in recent years, electromagnetic shielding technology has received much attention. The electromagnetic shielding, namely transparent electromagnetic shielding, which is required in visual observation occasions is always a difficult point and a hot point, and the application of the electromagnetic shielding, namely transparent electromagnetic shielding, comprises a medical electromagnetic isolation room observation window, a communication equipment transparent electromagnetic shielding element, an aerospace equipment optical window, an advanced optical instrument optical window, a confidential facility electromagnetic leakage prevention optical window, a liquid crystal display screen, a mobile phone touch screen, a vehicle-mounted transparent antenna and the like.
At present, the difficulty of realizing transparent electromagnetic shielding mainly lies in that most of traditional wave-absorbing materials are opaque or have poor transparency, and the transparency and the conductive shielding capability of the reflection transparent shielding technology based on transparent conductive materials or devices are mutually restricted, so that high transparency and strong electromagnetic shielding are difficult to realize simultaneously. In addition, the conductive reflective transparent shielding technology reflects electromagnetic radiation back to the space, which causes secondary pollution to the space environment and is not beneficial to the thorough prevention and treatment of electromagnetic pollution.
The transparent metal oxide film mainly made of indium tin oxide is widely applied to the visible light transparent occasions, but the light transmission waveband of the transparent metal oxide film is narrow, and the shielding capacity is not strong although the microwave shielding waveband is wide. The nano silver conductive network film can realize about 90% of light transmittance, but the nano silver wires have inevitable contact resistance, and particularly, the nano silver wires are very thin and sparse to enable the surface resistance of the nano silver wires to be higher when the nano silver wires are highly transparent, so that the shielding efficiency is reduced. The band-pass type frequency selective surface adopts a periodic resonance unit structure, can highly reflect interference microwaves outside an operating frequency band, but has poor light transmission and is difficult to realize a wide light transmission band. Therefore, the technical schemes can not meet the requirements of the electromagnetic shielding optical window on high light transmission and strong microwave shielding capability.
In contrast, the metal mesh grid with the period from millimeter to submillimeter is much shorter than the interference electromagnetic wavelength and much longer than the optical wavelength, so that the low-frequency broadband electromagnetic shielding can be realized, and meanwhile, the higher light transmittance of the visible light and the infrared band can be ensured. Therefore, the metal mesh grid with millimeter and sub-millimeter period is widely applied in the technical field of optical window electromagnetic shielding due to good transparent conductive performance:
1. patent 200810063988.0 entitled "an electromagnetic shielding optical window with double-layer square metal grid structure" describes an electromagnetic shielding optical window formed by placing square metal grids or metal wire nets with the same structural parameters in parallel on two sides of an optical window or a transparent substrate, which greatly improves the electromagnetic shielding efficiency.
2. Patent 200810063987.6 entitled "electromagnetic shielding optical window with double-layer circular ring metal grid structure" describes an electromagnetic shielding optical window formed by two layers of circular ring metal grids loaded on two sides of the optical window, which solves the problem that high light transmittance and strong electromagnetic shielding efficiency cannot be simultaneously considered.
3. Patent 201410051497.X "multi-period master-slave nested circular ring array electromagnetic shielding optical window with concentric circular rings" describes a metal mesh grid structure nested with the concentric circular rings and used for realizing the electromagnetic shielding function of the optical window, wherein the metal mesh grid structure enables stray light caused by high-level diffraction to be homogenized to a certain extent, and the influence of the mesh grid on the imaging quality of the optical window is reduced.
4. Patent 201410051496.5 entitled "electromagnetic shielding optical window with double-layer staggered multicycle metal ring nested array" describes an electromagnetic shielding optical window formed by two layers of staggered metal grids, which significantly reduces the nonuniformity of the grid diffraction light intensity distribution and the influence on imaging.
Patent 200810063988.0 and patent 200810063987.6 all adopt double-deck metal net bars parallel to place in the both sides of light window transparent substrate or substrate and constitute, and two-deck metal net bars have the same unit appearance and structural parameter, through the interval of optimizing two-layer net bars, have improved electromagnetic shielding efficiency. Patent 201410051497.X proposes a mesh grid structure with a master-slave nested circular ring array of multi-period concentric circular rings, which realizes the depth homogenization of high-order diffraction and reduces the influence on the imaging quality. Patent 201410051496.5 makes stray light distribution more even through the selection of double-layer grid stagger angle, and has less influence on imaging quality. In the above patents, the metal mesh grid (or the metal wire mesh) is used as a core device for microwave shielding, so that a better electromagnetic shielding effect and light transmittance can be realized, but when the metal is used as a reflective electromagnetic shielding material, a reflected radio frequency signal can cause secondary pollution to the space environment, and the prevention and treatment of electromagnetic pollution is not facilitated thoroughly.
Among many allotropes of carbon, graphene is a very typical material, and graphene is a hexagonal honeycomb lattice planar thin film composed of carbon atoms with sp2 hybrid orbitals, and is a two-dimensional material with only one carbon atom thickness, which has many excellent properties, one of the outstanding properties is excellent transparent conductivity and certain microwave absorption performance, so that graphene has a very high application value in the field of transparent electromagnetic shielding:
5. U.S. Pat. No. 20130068521, "graphene preparation method using graphene prepared by Chemical Vapor Deposition (CVD)" is loaded on a metal plate or a polymer substrate to realize Electromagnetic shielding, and compared with a metal plate or a polymer substrate which is not loaded with graphene, the Electromagnetic shielding efficiency of the whole structure is improved after the graphene is loaded.
6. Patent 201310232829.X "graphene-based structure and method for shielding electromagnetic radiation" describes an electromagnetic shielding structure for shielding electromagnetic radiation having a frequency greater than 1 mhz, the structure being composed of one or more layers of graphene, at least one layer of graphene being doped with a dopant.
7. Patent 201420099425.8 "a transparent electromagnetic shielding film based on graphene film" describes a transparent electromagnetic shielding film with nano-silver wires arranged between a transparent substrate and a graphene film, wherein the nano-silver wires act as a charge bridge to increase the conductivity of the whole electromagnetic shielding film and improve the shielding efficiency.
8. James M.Tour et al, Rice University (Rice University), USA, prepares a metal mesh with a line width of 5 μm by photolithography, and transfers single-layer Graphene on the surface thereof to prepare a Graphene-metal mesh mixed conductive film (James M.Tour et al, "random Design of Hybrid Graphene Films for High-Performance transmission Electrodes". ACS Nano, 2011, 5 (8): 6472-6479), which can realize a light transmittance of 90% and a sheet resistance of 20 Ω/sq.
9. Seul Ki Hong et al, Korea scientific and technical institute (KAIST), reported that the shielding efficiency of single-layer graphene was 2.27dB (Hong S K et al, "Electromagnetic interference shielding efficiency of monolayer graphene". Nanotechnology,2012,23 (45): 455704), with absorption and reflection losses of-4.38 dB and-13.66 dB, respectively.
10. Kim S of the University of Korea (Sungkyunkwan University) and Myeong-Gi, et al of the Korea three-star Motor company (Samsung Electro-Mechanics) use a polyetherimide/redox method to prepare a Graphene (PEI/RGO) laminate structure to achieve Electromagnetic Shielding (Kim S, et al, "Electromagnetic Interference (EMI) Transmission Shield of Reduced Graphene Oxide (RGO) Electromagnetic Interference disposed". AppACS plied materials & interfaces, Electromagnetic Shielding 2014,6 (20): 17647 17653), the efficiencies of the double-layer PEI/RGO and single-layer PEI/RGO laminates are 6.37 and 3.09dB, respectively, and the absorption loss accounts for 96% and 92% of the total efficiency, respectively.
11. Hanjie et al, Harbin university of Industrial science, uses a copper mesh as a sacrificial layer, and prepares a plurality of graphene meshes (Han J, et al, "isolated-transmissive film based on a modulated graphene network fabric for electronic shielding". Carbon,2015,87: 206-type 214) by Chemical Vapor Deposition (CVD), respectively achieving 70.85% Infrared transmittance and 12.86dB shielding efficiency, and achieving 87.85% Infrared transmittance and 4dB shielding efficiency. And the graphene grid electromagnetic shielding is also dominated by absorption.
According to the scheme, the graphene is used for electromagnetic shielding, and a certain electromagnetic shielding effect can be achieved. US20130068521 uses graphene as a core device of an electromagnetic shielding device, and transfers a whole large-area graphene onto substrates such as metal and polymer by a roll-to-roll graphene transfer method, so as to achieve an excellent electromagnetic shielding effect, but the electromagnetic shielding device does not have transparency. Patent 201310232829.X "graphene-based structure and method for shielding electromagnetic radiation" takes a graphene thin film as a main body of an electromagnetic shielding structure, and at least one layer of the graphene thin film is doped to improve the electromagnetic shielding efficiency, but the doping affects the light transmittance of the whole structure. Patent 201420099425.8, "a transparent electromagnetic shielding film based on graphene thin film", utilizes nano-silver wires to increase the conductivity of the graphene thin film and increase the reflection loss to achieve the improvement of the electromagnetic shielding efficiency, but the main contribution of the electromagnetic shielding is caused by reflection. In the document 8, the graphene film is loaded on the metal mesh to form a structure in which the graphene and the metal mesh are tightly attached to each other, so that the conductivity of the metal mesh is improved, and meanwhile, the light transmittance reaches 91%, but the electromagnetic shielding of the structure is mainly reflected. The research results in the above-mentioned document 9 indicate that although the shielding efficiency of graphene increases greatly as the number of layers increases, the absorption loss increases little, and the light transmittance is lost by 2.3% per one layer of graphene, making it difficult to achieve high light transmittance, low reflection, and strong electromagnetic shielding at the same time with this structure. In the above document 10, the graphene thin film (RGO) and Polyetherimide (PEI) laminated structure prepared by the redox method realizes electromagnetic shielding, and the shielding mainly involves absorption loss, but the shielding efficiency of the double-layer PEI/RGO structure is only 6.37dB, and the light transmittance is only 62%, and it is difficult to realize both strong electromagnetic shielding and high light transmittance. The document 11 only adopts a graphene grid structure, and the shielding efficiency is low, and the strong shielding efficiency and the high light transmittance cannot be obtained at the same time.
In a word, in the prior electromagnetic shielding technology, a method mainly based on reflection-type electromagnetic shielding is easy to cause secondary electromagnetic pollution; in the electromagnetic shielding method with absorption loss, either the light transmittance is not high or the electromagnetic shielding efficiency is not strong, so that it is difficult to realize high transparency and strong electromagnetic shielding at the same time.
Disclosure of Invention
The invention aims to overcome the defects of the existing transparent electromagnetic shielding technology, in particular to the problems that the transparency and the conductive shielding capability of the existing reflective transparent shielding technology are mutually restricted, the high light transmittance and the strong microwave shielding efficiency are difficult to be considered, and electromagnetic leakage and secondary pollution are caused by reflected electromagnetic signals.
The purpose of the invention is realized as follows: the graphene grid and double-layer metal grid transparent electromagnetic shielding device with the bidirectional wave-absorbing effect is formed by assembling a transparent absorption layer A, a transparent medium A, a metal grid A, a transparent medium B, a metal grid B, a transparent medium C and a transparent absorption layer B which are sequentially overlapped and arranged in parallel; the transparent absorption layers A and B are both composed of N layers of graphene grid films separated by transparent media, and the metal grid A and the metal grid B which are arranged in parallel form a transparent reflection layer.
The good effect produced by the invention is mainly focused on realizing the performance of simultaneously having bidirectional strong electromagnetic shielding, high light transmission and low electromagnetic reflection, and the good effect is as follows:
firstly, electromagnetic shielding with high light transmission and absorption as main functions is realized by utilizing different light transmission and microwave shielding characteristics shown when the graphene grid film has different aperture unit opening area ratios; when the aperture area ratio t of the mesh unit of the graphene grid film is between 0.05 and 0.7, good light transmission and shielding performance can be realized by adjusting the number of layers of the graphene grid film. When the opening area ratio t of the mesh unit of the graphene grid film meets the condition that t is more than or equal to 0.3 and less than or equal to 0.7, the light transmittance which is similar to that of a single-layer graphene film is realized by utilizing the multi-layer graphene grid film, and meanwhile, the shielding performance is improved; when the opening area ratio t of the mesh unit of the graphene grid film meets the condition that t is more than or equal to 0.05 and less than 0.3, the microwave shielding performance similar to that of a single-layer graphene film is realized by utilizing the single-layer graphene grid film, and meanwhile, the light transmittance is improved; meanwhile, the microwave shielding performance of the graphene grid film is mainly microwave absorption.
Secondly, the microwave absorption characteristic of the graphene grid film and the strong microwave reflection characteristic of the double-layer metal grid are organically combined, the double-layer metal grid is used as a transparent reflection layer, and compared with a single-layer metal grid, the microwave shielding efficiency and the reflectivity are remarkably improved on the premise that the light transmission performance is not changed, and strong electromagnetic shielding and reflection of radio frequency radiation can be better realized; the N layers of graphene grid thin film structures separated by transparent media are used as transparent absorption layers, so that radio frequency radiation can be partially absorbed and pass through the transparent absorption layers in a low-reflection mode; two groups of transparent absorption layers are respectively arranged on two sides of the transparent reflection layer, so that the microwave which penetrates through the transparent absorption layers is strongly reflected back to the transparent absorption layers, and good electromagnetic shielding is realized through reflection and multiple absorption; two groups of transparent absorption layers are respectively arranged on two sides of the transparent reflection layer to form an electromagnetic shielding device, and simultaneously absorb radio frequency radiation on the inner side and the outer side of the electromagnetic shielding device, so that the radio frequency radiation from two sides of the electromagnetic shielding device is reflected and absorbed for multiple times, and finally, bidirectional low-reflection strong electromagnetic shielding is realized.
According to the laminated structure, on one hand, due to the existence of the transparent absorption layer, the problem that secondary electromagnetic pollution is easily caused by shielding mainly based on reflection when only a metal mesh is provided is solved; on the other hand, due to the existence of the transparent reflecting layer and the arrangement between the two groups of transparent absorbing layers, microwaves to be shielded from two sides of the electromagnetic shielding device are reflected and absorbed for multiple times, so that the problem of low shielding efficiency when only the graphene grid film absorbing layer exists is solved, the bidirectional shielding effect is achieved, and the bidirectional shielding effect is mainly absorption; meanwhile, for light waves, the light waves only penetrate through the transparent absorption layer and the transparent reflection layer once, the loss is less, and when the opening area ratio t of the mesh units of the graphene grid film is between 0.05 and 0.7, the graphene grid film has a periodic opening structure, so that the light transmission performance is improved, and the high light transmission characteristic can be realized; and when the double-layer metal mesh grid adopts a mesh grid structure with uniform distribution of diffracted stray light, the influence of the whole laminated structure on the imaging quality is very low.
In conclusion, the invention has the most outstanding effects of simultaneously having bidirectional strong electromagnetic shielding, high light transmission and low electromagnetic reflection performance.
Drawings
Fig. 1 is a schematic cross-sectional view of a transparent electromagnetic shielding device with a graphene grid and a double-layer metal grid having a bidirectional wave-absorbing effect.
Fig. 2 is a schematic structural diagram of a grid unit arrangement mode of a square-hole graphene grid.
Fig. 3 is a schematic structural diagram of a grid unit arrangement mode of a circular hole graphene grid.
Fig. 4 is a schematic structural diagram of a grid unit arrangement of a grid metal grid.
Fig. 5 is a schematic structural diagram of an arrangement mode of grid units of a circular ring metal grid.
Fig. 6 is a schematic diagram of the arrangement of grid cells of the multi-period micro-ring metal grid.
Fig. 7 is a schematic cross-sectional view of the transparent electromagnetic shielding device with a graphene grid and a double-layer metal grid having a bidirectional wave-absorbing effect according to the embodiment.
Fig. 8 is a schematic structural view of the transparent electromagnetic shielding device with the graphene grid and the double-layer metal grid having the bidirectional wave-absorbing effect according to the embodiment.
Description of part numbers in the figures: 1. the protective layer A2, the antireflection film A3, the transparent absorption layer A4, the transparent medium A5, the metal mesh A6, the transparent medium B7, the metal mesh B8, the transparent medium C9, the transparent absorption layer B10, the antireflection film B11, the protective layer B12, the square-hole graphene mesh film A13, the transparent medium D14, the square-hole graphene mesh film B15 and the square-hole graphene mesh film C.
Detailed Description
Embodiments of the invention are described in detail below with reference to the accompanying drawings:
the electromagnetic shielding device is formed by assembling a transparent absorption layer A (3), a transparent medium A (4), a metal mesh grid A (5), a transparent medium B (6), a metal mesh grid B (7), a transparent medium C (8) and a transparent absorption layer B (9) which are sequentially overlapped and arranged in parallel; the transparent absorption layers A, B (3, 9) are both composed of N layers of graphene grid films separated by transparent media, and the metal grid A (5) and the metal grid B (7) which are arranged in parallel form a transparent reflection layer. The graphene grid film forming the transparent absorption layer A, B (3, 9) is formed by a graphene film with a mesh array structure; the mesh array structure is a two-dimensional array structure formed by periodically arranging mesh units; the mesh units are in the shape of square holes or round holes; the mesh unit size is in the range of submicron to millimeter, and the mesh unit array period is in the range of micron to millimeter; the opening area ratio t of the mesh units is between 0.05 and 0.7; the open area ratio of the mesh unit refers to the ratio of the open area of the mesh unit to the unit area of the array period in one array period.
Arranging a single-layer or multi-layer antireflection film A (2) and a single-layer or multi-layer protective layer A (1) in parallel on the outer side part of the transparent absorption layer A (3) in sequence; a single-layer or multi-layer antireflection film B (10) and a single-layer or multi-layer protective layer B (11) are arranged in parallel on the outer side of the transparent absorption layer B (9) in sequence.
When the ratio t of the open area of the mesh unit of the graphene grid film satisfies 0.3. ltoreq. t.ltoreq.0.7, the transparent absorption layer A, B (3, 9) is composed of N layers of the graphene grid film separated by a transparent medium, wherein N.ltoreq.6 { [1/(1-t) ] +1}, and [1/(1-t) ] represents a maximum positive integer not exceeding 1/(1-t).
When the ratio t of the open area of the mesh units of the graphene grid film is more than or equal to 0.05 and less than or equal to 0.3, the transparent absorption layers A, B (3 and 9) are formed by N graphene grid films separated by transparent media, wherein N is less than or equal to 6.
The metal grids A, B (5, 7) are both composed of two-dimensional plane structures with grid units arranged periodically, the period of the grid units is sub-millimeter to millimeter magnitude, the width of the metal lines is sub-micrometer to micrometer magnitude, and connecting metal for communicating the two metal lines is arranged between the adjacent grid units through metal line overlapping or at the overlapping position.
The distance between the metal mesh grid A (5) and the metal mesh grid B (7) is millimeter magnitude, and the distance is less than 0.25 time of the minimum shielding wavelength.
The number of graphene grid films constituting the transparent absorbing layer A, B (3, 9) is a single layer, a double layer or a triple layer, and the number of graphene grid films separated by the transparent medium may be the same or different.
The metal grids A, B (5, 7) are made of alloy materials with good conductivity, and the thickness of the alloy is larger than 100 nm.
The transparent reflective layer made of metal mesh A, B (5, 7) has a light transmittance of greater than 90%.
The transparent medium A, B, C (4, 6, 8) and the transparent medium manufacturing material for separating the transparent absorbing layer A, B (3, 9) and the graphene grid film comprise common glass, quartz glass, infrared materials and transparent resin materials.
According to the graphene grid and double-layer metal grid transparent electromagnetic shielding device with the bidirectional wave-absorbing effect, the distance between the double-layer metal grid A5 and the double-layer metal grid B7 forming the transparent reflecting layer is in millimeter order, and compared with a single-layer metal grid structure, the microwave shielding effect of the electromagnetic shielding optical window can be remarkably improved under the condition that the light transmittance is not changed.
Examples
The electromagnetic shielding device is formed by assembling a transparent absorption layer A3, a transparent medium A4, a metal mesh grid A5, a transparent medium B6, a metal mesh grid B7, a transparent medium C8 and a transparent absorption layer B9 which are sequentially overlapped and arranged in parallel; the transparent absorption layer A3 is composed of a single-layer graphene grid film A12, a transparent medium D13 and a single-layer graphene grid film B14 which are sequentially arranged in parallel, the transparent absorption layer B9 is composed of a single-layer graphene grid film C15, and a transparent reflection layer is composed of a metal grid A5 and a metal grid B7 which are arranged in parallel.
The invention has the technical effects that: when the electromagnetic shielding efficiency of the double-layer metal grid is 29.8dB, if radio frequency radiation comes from the outer side of the transparent absorption layer A3 of the electromagnetic shielding device, the electromagnetic shielding efficiency of the double-layer metal grid is 34.55dB, and the absorption loss accounts for 58.7 percent of the total shielding energy; if the radio frequency radiation comes from the outer side of the transparent absorbing layer B7 of the electromagnetic shielding device, the absorption loss accounts for 49.9 percent of the total shielding energy; the electromagnetic shielding device has the advantages that strong electromagnetic shielding mainly based on absorption is realized for radio frequency radiation on two sides of the electromagnetic shielding device with the structure, the light transmittance is 88.1%, and the electromagnetic shielding device still has high light transmittance. If radio frequency radiation comes from the outer side of a transparent absorption layer A3 of the electromagnetic shielding device, the electromagnetic shielding efficiency is 24.2dB, and the absorption loss accounts for 56.8% of the total shielding energy; if the radio frequency radiation comes from the outer side of the transparent absorbing layer B7 of the electromagnetic shielding device, the absorption loss accounts for 51.2 percent of the total shielding energy, and the light transmittance is 88.1 percent. Compared with a simulation result that a single-layer micro-ring metal mesh grid is used as a transparent reflecting layer, the graphene mesh grid with the bidirectional wave-absorbing effect and the double-layer metal mesh grid transparent electromagnetic shielding device have the advantage that the microwave shielding performance is remarkably improved under the condition that the light transmittance is kept unchanged.
The invention also corresponds to other embodiments, changes the shape and the structural parameters of the grid units of the double-layer metal grid in the figure 7 and the arrangement mode of the grid units, keeps the original arrangement mode of each layer unchanged, and finally can obtain similar effect; increasing or decreasing the number of layers of the graphene grid thin film separated by the transparent medium in the transparent absorption layer in fig. 7 will increase the absorption loss or increase the light transmittance, and can be adjusted accordingly according to actual needs.

Claims (6)

1. Graphene net bars and double-deck metal net bars transparent electromagnetic shield device with two-way wave absorption effect, its characterized in that: the electromagnetic shielding device is formed by assembling a transparent absorption layer A (3), a transparent medium A (4), a metal mesh grid A (5), a transparent medium B (6), a metal mesh grid B (7), a transparent medium C (8) and a transparent absorption layer B (9) which are sequentially overlapped and arranged in parallel; the transparent absorption layer A (3) and the transparent absorption layer B (9) are both formed by N layers of graphene grid films separated by transparent media, and the metal grid A (5) and the metal grid B (7) which are arranged in parallel form a transparent reflection layer; the graphene grid film forming the transparent absorption layer A (3) and the transparent absorption layer B (9) is formed by a graphene film with a mesh array structure; the mesh array structure is a two-dimensional array structure formed by periodically arranging mesh units; the mesh units are in the shape of square holes or round holes; the mesh unit size is in the range of submicron to millimeter, and the mesh unit array period is in the range of micron to millimeter; the opening area ratio t of the mesh units is between 0.05 and 0.7; the ratio of the open area of the mesh units refers to the ratio of the open area of the mesh units to the area of the units in an array period; when the ratio t of the open area of the mesh units of the graphene grid film satisfies 0.3 ≤ t ≤ 0.7, the transparent absorption layer A (3) and the transparent absorption layer B (9) are composed of N layers of graphene grid films separated by transparent medium, wherein N ≤ 6 × { [1/(1-t) ] +1}, [1/(1-t) ] represents the maximum positive integer of not more than 1/(1-t); when the ratio t of the opening area of the mesh units of the graphene grid film is more than or equal to 0.05 and less than 0.3, the transparent absorption layer A (3) and the transparent absorption layer B (9) are formed by N graphene grid films separated by transparent media, wherein N is less than or equal to 6; the metal mesh grid A (5) and the metal mesh grid B (7) are both formed by two-dimensional plane structures in which mesh grid units are periodically arranged, the period of each mesh grid unit is in the magnitude of submillimeter to millimeter, the width of metal lines of the metal mesh grid A (5) and the metal mesh grid B (7) is in the magnitude of submicrometer to micrometer, and connecting metal for communicating the two metal lines is arranged between the adjacent mesh grid units through metal line overlapping or at the overlapping position; the distance between the metal mesh grid A (5) and the metal mesh grid B (7) is millimeter magnitude, and the distance is less than 0.25 time of the minimum shielding wavelength.
2. The transparent electromagnetic shielding device with the bidirectional wave-absorbing function for the graphene grids and the double-layer metal grids of claim 1 is characterized in that: arranging a single-layer or multi-layer antireflection film A (2) and a single-layer or multi-layer protective layer A (1) in parallel on the outer side part of the transparent absorption layer A (3) in sequence; a single-layer or multi-layer antireflection film B (10) and a single-layer or multi-layer protective layer B (11) are arranged in parallel on the outer side of the transparent absorption layer B (9) in sequence.
3. The transparent electromagnetic shielding device with the bidirectional wave-absorbing function for the graphene grids and the double-layer metal grids of claim 1 is characterized in that: the number of layers of the graphene grid films which form the transparent absorption layer A (3) and the transparent absorption layer B (9) and are separated by the transparent medium is the same or different.
4. The transparent electromagnetic shielding device with the bidirectional wave-absorbing function for the graphene grids and the double-layer metal grids of claim 1 is characterized in that: the metal mesh grid A (5) and the metal mesh grid B (7) are both made of alloy materials with good conductivity, and the thickness of the alloy is larger than 100 nm.
5. The transparent electromagnetic shielding device with the bidirectional wave-absorbing function for the graphene grids and the double-layer metal grids of claim 1 is characterized in that: the light transmittance of the transparent reflecting layer consisting of the metal mesh A (5) and the metal mesh B (7) is more than 90 percent.
6. The transparent electromagnetic shielding device with the bidirectional wave-absorbing function for the graphene grids and the double-layer metal grids of claim 1 is characterized in that: the transparent medium manufacturing materials among the transparent medium A (4), the transparent medium B (6), the transparent medium C (8) and the graphene grid thin film for separating the transparent absorption layer A (3) and the transparent absorption layer B (9) comprise common glass, quartz glass, infrared materials and transparent resin materials.
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