KR100524637B1 - Radio wave absorbing panel - Google Patents

Abstract

The radio wave absorbing panel is composed of a central insulating substrate disposed in equilibrium between a first insulating substrate, a second insulating substrate, and a first insulating substrate and a second insulating substrate, which are disposed in equilibrium at a predetermined distance. Each of the first and second insulating substrates has a conductive film coated on its entire surface. On one surface of the central insulating substrate is coated with a multilayer conductive film arranged in a row or matrix form. By this means, a thin radio wave absorption panel having excellent radio wave absorption capacity and light permeability can be obtained.

Description

Radio wave absorption panel {RADIO WAVE ABSORBING PANEL}

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates generally to absorbing panels for absorbing radio waves entering a building, and more particularly to radio wave absorbing panels that absorb incoming radio waves and transmit visible light.

In recent years, with the increase in the number of high-rise buildings, the case of radio waves in the TV frequency range such as VHF and UHF reflected in the building has become commonplace. Therefore, ghosting, that is, a phenomenon that appears on the TV screen when the radio wave (direct wave) reaching the antenna of the TV receiver directly from the TV base station and the radio wave reflected by the building (reflected wave) are incident on the antenna at the same time. Is a serious social problem. For this reason, in order to reduce the number of these radio waves reflected by the building's exterior walls, radio wave absorption panels made of magnetic materials such as ferrites were fixed or embedded outside the walls to absorb radio waves entering the building.

However, in the glass windows installed in the building windows, in order to reduce the cooling load of the air conditioner in the summer (for energy saving), glass coated with a film having a heat ray reflection function is used. Because of their low radio wave reflectivity, this is a cause of radio wave disturbances.

Radio wave absorbing panels for reducing radio wave reflection using ferrite cannot be applied to building windows because ferrite does not transmit visible light. Therefore, due to this situation, heat reflecting ability is sacrificed and transparent heat reflecting film having relatively high electric resistance is used to coat the windows of the building to reduce the reflection of radio waves and to transmit radio waves through the windows to the inside of the building, thereby preventing radio waves. Is blocking.

Regarding the windows of buildings and vehicles, according to known techniques (for example, from Japanese Patent Laid-Open Nos. 3-250797, 5-042623, 5-050548 and 7-242441), high-performance heat reflecting film In order to prevent the interference caused by the reflection of radio waves, the conductive film divided into a region sufficiently smaller than the wavelength of the incident radio wave is used to realize high heat ray reflectivity and low radio wave reflectance at the same time, thereby improving radio wave permeability. .

In the related art, radio wave absorbing panels having radio wave permeability attempt to prevent radio wave reflection problem by providing radio wave permeability to the glass window of the building. Affects the same office equipment, and electromagnetic radiation emitted from electrical equipment inside the building leaks out of the building through glass windows. Although this type of radio wave disturbance is expected to increase further in the future, no effective countermeasures have been taken other than to block radio waves by using reflective and conductive lines or conductive films in the windows of buildings, and radio wave reflection disturbances may increase. Where possible, it is difficult to build buildings with large windows or to prevent radio waves.

In order to solve this problem, it is necessary to provide a practically useful transparent panel that absorbs instead of reflecting or transmitting radio waves.

Currently, there are radio wave absorbing panels made to equilibrate two transparent substrates, each coated with a conductive film with a controlled sheet resistivity, by using resonance due to the interference of multiple reflections of the radio wave. High radio wave absorption ability can be realized. However, in order to absorb radio waves in the VHF region (about 100 MHz), the distance between the two substrates constituting the radio wave absorption panel should be made from several tens of centimeters to more than 1 m. Few.

Preferred embodiments of the present invention will be described in more detail with reference to the accompanying drawings, wherein;

1 is a partial cross-sectional view showing the structure of a radio wave absorption panel according to the present invention,

Figure 2 is a state diagram showing a conductive film according to the present invention arranged in a row shape,

3 is a state diagram showing a conductive film according to the present invention arranged in a matrix form,

4A is a structural diagram of an insulating substrate having a stripe conductive film formed on a surface thereof, FIG. 4B is a plan view of a stripe conductive film, FIG. 4C is a cross-sectional view taken along line C-C of FIG. 4B,

5 is a diagram illustrating radio wave conduction reflection and absorption frequency characteristics when an insulating substrate on which a strip-shaped conductive film is formed is not embedded between two opposing insulating substrates.

6 is a diagram illustrating radio wave conduction reflection and absorption frequency characteristics when an insulation substrate on which a row-shaped conduction film is formed is embedded between two opposing insulation substrates according to the present invention.

7 is a graph showing the theoretical calculation results obtained for the first embodiment of the present invention,

8 is a graph showing the theoretical calculation results obtained for the first comparative example.

Accordingly, it is an object of the present invention to provide a radio wave absorption panel having excellent radio wave absorption and light permeability.

In order to achieve this and other objects, the present invention is arranged in equilibrium with at least two or more insulating substrates and at least two insulating substrates each having a continuous conductive film formed on at least one surface and disposed in equilibrium at a predetermined distance apart from each other. And at least one insulating substrate having a stripe or matrix conductive film formed on the surface thereof.

As a result, the present invention can increase the radio wave absorbance even if the relative permittivity of the radio wave absorbing panel becomes large and the thickness of the panel becomes thin. Therefore, the present invention is suitable to be installed in, for example, the open window of a building. It can be applied to the VHF area radio wave absorption panel.

In the radio wave absorption panel according to the present invention, suitably, when a continuous conductive film is used, the sheet resistivity of the continuous conductive film is 1 Ω / □ to 3000 Ω / □, and each width of the conductive film arranged in a string shape When the sheet resistivity is expressed as Hcm and R _BM Ω / □, respectively, and the insulation resistance of the insulating substrate on which a strip-shaped conductive film is formed is represented as R _D cmΩ, H, R _BM and R _D are 1 cm≤H 50 cm, 1 dB / □ ≦ R _BM ≦ 40 dB / □, R _D ≧ 30,000 cm 0,000. When a string-shaped conductive film having such a value is used, the relative permittivity of the radio wave absorption panel can be large and its radio wave absorption is increased, and even if the panel is thin, improving the absorbency of the radio wave reached from the fixed direction is reduced. It is possible.

When the matrix type conductive film is used, suitably the continuous sheet resistivity of the continuous film is 1 Ω / □ to 3000 Ω / □, and the width, length and sheet resistivity of each conductive film arranged in the matrix form are Hcm, Vcm, And R _BM Ω / □, and when the insulation resistance of the insulating substrate on which the matrix type conductive film is formed is represented by R _D cmΩ, H, V, R _BM , and R _D are 1 cm ≦ H ≦ 50 cm, 1 cm ≤ V ≤ 50 cm and 1 Ω / □ ≤ R _BM ≤ 40 Ω / □. When a matrix type conductive film having such a value is used, the relative permittivity of the radio wave absorption panel can be large and its radio wave absorption is increased, and even if the panel is thin, it is desirable to improve the radio paradox absorbance reached from any direction. It is possible.

In addition, when a strip-shaped conductive film is used, the sheet resistivity of the continuous conductive film formed on the surface of one insulating substrate is suitably not greater than 30 mW / square, and the sheet resistivity of the continuous conductive film formed on the surface of the other insulating substrate. Is 50 mV / □ to 3000 mV / □, and the width and sheet resistivity of each conductive film arranged in a row shape are represented by Hcm and R _BM Ω / □, respectively, and insulation of the insulating substrate on which the conductive film is arranged in a row shape is formed. When the resistance is expressed by R _D cmΩ, H, R _BM and R _D become 1 cm ≦ H ≦ 50 cm, 1 dB / □ ≦ R _BM ≦ 40 dB / □, R _D ≧ 30,000 cm0,000. The sheet resistivity of the conductive film on one insulated substrate is not greater than 30 mW / square, and the sheet resistivity of the conductive film of the other insulated substrate is 50 mW / square to 3000 mV / square, thereby maintaining the increased radio wave absorption capacity. It is possible to make the panel thinner.

In addition, when the matrix type conductive film is used, the sheet resistivity of the continuous conductive film formed on the surface of one insulating substrate is not larger than 30 k? / Square, but the sheet resistivity of the continuous conductive film formed on the surface of the other insulating substrate. Is 50 mV / □ to 3000 mV / □, and the width, length, and sheet resistivity of each conductive film arranged in a matrix form are represented by Hcm, Vcm and R _BM Ω / □, respectively. When the insulation resistance of the formed insulating substrate is represented by R _D cmΩ, H, V, R _BM and R _D are 1 cm≤H≤50cm, 1cm≤V≤50cm, 1Ω / □ ≤R _BM ≤40Ω / □, R is a _D ≥30,000㎝Ω. The sheet resistivity of the conductive film on one insulated substrate is not larger than 30 mW / square, and the sheet resistivity of the conductive film of the other insulated substrate is 50 mW / square to 3000 mV / square by this method, and the matrix type is set to a predetermined value. Since the conductive film is used, it is possible to increase the relative permittivity of the radio wave absorption panel and to increase its radio wave absorption capacity.

Suitably, the transparent plate glass is used as the insulating substrate and the strip or matrix conductive film is a transparent conductive film mainly composed of SnO ₂ or In ₂ O ₃ or a metal film mainly composed of Ag, Au, Cu, or Al, thereby It is possible to lower the sheet resistivity of the conductive film and to increase their light transmittance.

Further, suitably, dry air may be sealed in a space between at least two insulating substrates and at least one insulating substrate on which a conductive film arranged in a stripe or matrix form is formed on the surface thereof, thereby preventing external temperature change. Condensation caused by this can be prevented, and inhibition of the radio wave absorption ability due to water vapor in the conductive film can be prevented.

On the other hand, the resin can be sealed in the space between the at least two insulating substrates and the insulating substrate having a conductive film arranged in the form of a strip or matrix on the surface thereof to be suitable to form a laminated glass structure, thereby Splitting and dispersion can be prevented.

The present invention provides a thin radio wave absorption panel which can be applied to window glass of a building and prevents reflection of the radio wave and transmission of the radio wave into the building by absorbing visible light and absorbing radio waves from the outside. .

In FIG. 1, the radio wave absorption panel 1 includes a first insulating film 2 forming one surface of the panel, a first conductive film 3 coated on the entire inner surface of the first insulating substrate 2, and a first insulating film 2. The second insulating film 6 coated on the entire surface of the inner surface of the second insulating substrate 6 and the second insulating substrate 6, which is disposed in equilibrium with a predetermined distance from the insulating substrate 2 to form another surface of the panel. A central insulating substrate 4 disposed in equilibrium between the first insulating substrate 2 and the second insulating substrate 6, and a conductive film coated on the surface of the central insulating substrate 4 in the form of a string or a matrix ( 5) consists of. The insulating substrates 2, 6 and 4 are firmly fixed and the air layer 8 is sealed.

Although the radio wave absorption panel 1 in the embodiment shown in FIG. 1 has a three-layer structure composed of the first insulating substrate 2, the central insulating substrate 4, and the second insulating substrate 6, The panel 1 may be selectively composed of a plurality of such three-layer structures.

In addition, the first conductive film 3 and the second conductive film 7 may be continuously coated on the outer surfaces of the first and second insulating substrates 2 and 6, respectively, or on both surfaces of the second insulating substrate 6. It can also be applied continuously.

In addition, a plurality of central insulating substrates 4 may be disposed between the first insulating substrate 2 and the second insulating substrate 6.

Alternatively, a single central insulating substrate 4 and one or more conventional insulating substrates may be disposed between the first insulating substrate 2 and the second insulating substrate 6.

Figure 2 shows the form of a row-shaped conductive film of the radio wave absorption panel according to the present invention.

As shown in Fig. 2, the row-shaped conductive film 5A has a width H of the row and a gap D between adjacent rows.

Figure 3 shows the form of the matrix type conductive film of the radio wave absorption panel according to the present invention.

In Fig. 3, the matrix of the conductive film 5B is composed of a plurality of rectangular film pieces arranged in a matrix. The widths of the film pieces in the transverse and longitudinal directions are H and V, respectively, and the transverse and longitudinal spacings between adjacent sections are D.

4A to 4C are views of an insulating substrate according to the present invention in which a row-shaped conductive film is formed on its surface.

FIG. 4A shows the structure of the central insulating substrate 4 having the row-shaped conductive film 5A formed on the surface thereof, and also shows the action of the irregular radio wave region imprinted on the row-shaped conductive film 5A. FIG. 4B shows the form of the row-shaped conductive film 5A, and FIG. 4C is a cross-sectional view of the row-shaped conductive film 5A shown by the C-C line in FIG. 4B.

In FIG. 4A, the y-axis direction vector represents the direction of the irregular magnetic field region and the vector α having an oblique line of the x-z coordinate represents the propagation direction of the electromagnetic wave.

In Fig. 4C, the major axis of the planar ellipse of each of the row-shaped conductive films 5A in cross section (the width of the row-shaped film) is H, the minor axis (the thickness of the film) is A, and the distance from the adjacent row-shaped film is D to be. The insulation resistance between adjacent stripe films is represented by R _D , and the relative permittivity around the planar ellipse film is represented by ε ^eX .

In general, when two insulating substrates are formed in equilibrium (i.e., in addition to the air layer 8 in FIG. 1) when two insulating substrates having conductive films formed on each front face are arranged in equilibrium for absorption of radio waves accompanied by resonance due to interference of multiple reflections. In the absence of (4), it is essential that the distance between the two substrates be about one quarter of the radio wave wavelength. Therefore, since the relative permittivity is 1 when the space between the two substrates is an air layer, for example, for a radio wave with a frequency of 100 MHz, the distance between the two substrates should be 75 cm. When glass with high relative permittivity is used instead of air, its relative permittivity is about 7, so the distance between the substrates should be about 28 cm. To reduce the spacing between the two substrates to about 10 cm, for radio waves with a frequency of 100 MHz, an intermediary with dozens or more of relative permittivity is needed.

In a study conducted by the present inventors, it is shown that the conductive film 5A divided into strips as shown in FIG. 4C has a characteristic perpendicular to the center line of the interval between adjacent stripe films with respect to the radio wave region in a certain state. If the film thickness of the row-shaped conductive film 5A is expressed in Acm and the principal axis of the planar ellipse in the cross section of the film is expressed in Hcm, it has a large actual relative permittivity (typically about 10 ⁷ ) of about H / A, It can also be regarded as a continuous intermediate of thickness Acm.

The radio wave absorbing panel according to the present invention has the same function as when an insulator film having a large real dielectric constant of this kind is disposed between two insulated substrates each having a continuous insulating film formed thereon and arranged in parallel, and having a row shape or matrix The conductive film divided into molds can have a large phase change effect on the radio wave. As a result, even if the distance between the two substrates (panel thickness) is much smaller than 1/4 of the wavelength, resonance induced by interference of multiple reflections can be generated, thereby achieving high radio wave absorption capability.

Next, the appropriate calculation of the large actual permittivity mentioned above can be performed based on a simple model.

The modeling takes the stripe conductive film 5A as a planar elliptical prism extending in a direction perpendicular to the direction (y-axis direction) of the radio wave region as shown in Fig. 4C, and the spacing between adjacent elliptical prisms is defined as insulation resistance R Formed by _D and distance (width) D, carried out by enclosing an elliptical prism with an insulator of relative permittivity ε ^eX ; The polarization effect when a constant outer region is imprinted on this one elliptical prism is calculated and the effective relative permittivity ∑ _BM of this insulating layer is given by equation (1) by spatial leveling through the entire layer of the divided insulating film.

… … (One)

here:

A is an auxiliary axis of the elliptical prism (corresponding to the thickness of the conductive film);

H is the main axis of the elliptical prism (corresponding to the width of the strip-shaped conductive film);

D is the width of the high resistance section for dividing the adjacent stripe-shaped film;

k is coverage, (π / 4) AH / {A (H + D)};

λ is the wavelength [cm] in the vacuum of the incident radio wave.

Z _o is the space resistance of vacuum, 4πc / 109 ≒ 377Ω;

R _BM is the sheet resistivity of the strip-shaped film [줄 / □]; And

R _D is the insulation resistance [cmΩ] between adjacent stripe films of unit length.

When the stripe-shaped insulating film, the spacing between the resistor R _D R _D is large enough to be at infinity, Equation 1 can be simplified as equation (2).

… … (2)

Further, the main axis H of the elliptical conductive film is set at a value sufficiently smaller than the wavelength λ of the incident radio wave (H << λ) and the sheet resistivity R _BM of the conductive film is set at a value sufficiently smaller than the space resistance Z _o of the vacuum. When R _BM << Z _o , equation (2) can be simplified to equation (3).

… … (3)

From equation (3), the effective relative dielectric constant? _BM of the actual insulating layer of the row conductive film 5A shown in Figs. 4A to 4C corresponds to a large actual relative dielectric constant (about 10 ⁷ ).

Radio wave when the equation (3) relative dielectric constant of Σ the insulating substrate sandwiched therebetween using the _BM is formed a conducting film divided into stripe-shaped two insulating substrate having a conductive film continuously on each disposed in equilibrium shown in The transmission, reflection and absorption properties are calculated by Maxwell's equation.

The radio wave transmission, reflection and absorption frequency characteristics of two insulating substrates each having a continuous conductive film formed thereon are formed when the insulating substrate having a conductive film divided into rows is not sandwiched or sandwiched between them. 5 and 6.

5 shows radio wave transmission, reflection, and absorption characteristics when an insulating substrate on which a conductive film divided into strips is formed is not provided. In this case, the thickness of the air layer is 60 cm between two insulating substrates each having a conductive film formed thereon.

In FIG. 5, the radio wave absorbance is very large (absorbance = 1) near the frequency 100 MHz, and the radio wave reflectance is greatly reduced (reflectivity = 0.011; attenuation 60 Hz).

FIG. 6 shows radio wave transmission, reflection and absorption frequency characteristics when a central insulating substrate having a conductive film divided into strips according to the present invention is mediated between the first and second insulating substrates. As shown in FIG. 1, the distance between the first insulating substrate 2 and the central insulating substrate 4 is 15 cm, and the distance between the central insulating substrate 4 and the second insulating substrate 6 is 1 cm. It becomes

In FIG. 6, the radio wave absorbance is very large (absorbance = 1) near the frequency 100 MHz, and the radio wave reflectance is greatly reduced (reflectivity = 0.01; attenuation 40 Hz).

In this way, the radio wave absorbing panel according to the present invention is divided into a strip since a central insulating board having a conductive film divided into a strip is provided between at least two insulating substrates having a continuous conductive film respectively formed therein. Even if the panel width is reduced to a quarter compared with the absence of a central insulating substrate on which the conductive film is formed, the radio wave reflectance can be reduced and the absorbance is increased.

The characteristics of the conductive film used in the radio wave absorption panel of the present invention have the function of reflecting almost 100% of the radio waves and of reflecting or transmitting some of the radio waves and slightly absorbing them.

In order to obtain the former characteristics, a conductive film having a small sheet resistivity R _BM is suitable, but in order to reduce the sheet resistivity R _BM , it is necessary to thicken the conductive film and its manufacturing cost is increased. Also, if a metal film is used as the conductive film, its transmission to visible light is reduced when the conductive film is thick. For this reason, the sheet resistivity R _BM is set between 1 mW / square and 3000 mV / square to solve the problems of manufacturing cost and visible light transmittance. In addition, sheet resistivity R _BM is set between 5 kV / square and 20 kV / square as most suitable in order to obtain visible light transmittance which is not significantly different from ordinary transparent glass.

In the latter case, the radio wave absorption characteristics vary when multiple insulated substrates coated with a continuous conductive film are used, and the absorption of the radio waves is too large when the sheet resistivity R _BM is 3000 Ω / □ or more, so that sufficient absorption is achieved. When the sheet resistivity R _BM is 50 kV / square or less, it is difficult to obtain sufficient absorption because the radio wave reflection is too large. Therefore, the sheet resistivity R _BM is suitably set between 200 kV / square and 1500 kV / square.

In the characterization of a stripe or matrix conductive film, the effective relative permittivity ∑ _BM must be large to increase radio wave absorption. When the actual portion of the relative dielectric constant ∑ _BM is not large enough compared to the imaginary portion, resonance is not reliably generated and the absorption is inferior, so that the major axis H of the elliptical conducting film is set at a value sufficiently smaller than the wavelength λ of the incident radio wave ( H << λ) It is important that the sheet resistivity R _BM of the conductive film is set sufficiently less than the vacuum space resistance Z _o (R _BM << Z _o ).

From equation (3), the relative permittivity ∑ _BM can be set to a large value when the width H of the string-shaped conductive film becomes large, but the wavelength λ of the reached radio wave is about 300 cm in the VHF band, so H << λ To achieve this, the width H of the strip-shaped conductive film must be smaller than 50 cm.

When the width H of the strip-shaped conductive film becomes small, the relative permittivity Σ _BM becomes small, thereby making the radio wave absorption capacity small and making the conductive film difficult. For this reason, the value of H should typically be set at least 1 cm (H ≧ 1 cm). In other words, the width H of each row-shaped conductive film should be in the range of 1 cm ≤ H ≤ 50 cm.

For the same reason as for the stripe conductive film, the longitudinal pattern width V of each matrix type conductive film shown in FIG. 3 is also in the range of 1 cm ≤ V ≤ 50 cm.

The sheet resistivity R _BM of the strip-shaped conductive film must be sufficiently smaller than the space resistance Z _o of the vacuum as described above (R _BM << Z _o Ω 377 Ω), and typically the sheet resistivity R _BM is 40 Ω / □ (R _BM ² should not be set higher than 40Ω / □).

However, in order to reduce the sheet resistivity R _BM , it is necessary to increase the thickness of the conductive film and the manufacturing cost increases. When the film thickness of the conductive film and the metal film is used as the conductive film, a problem occurs that the transmittance of visible light decreases. For this reason, the sheet resistivity R _BM should be set to at least 1 dB / □ (R _BM ? 1 dB / □), suitably from 5 dB / □ to 20 dB / □.

In the state where the relative dielectric constant? _BM is larger than the imaginary part, the insulation resistance R _D of the gap between adjacent stripe films needs to be large as shown in equation (4).

… (4)

Typically, the width H of the row-shaped conductive film is generally amplified larger than the spacing D of the adjacent row-shaped film (H >> D) and is applied to equation (4) to obtain equation (5).

… (5)

Substituting the radio wave wavelength λ = 300 cm, relative permittivity ε ^eX = 7 (glass), and Z _o = 377 에 into equation (5), insulation resistance R _D ≫3300 cm As a result, the insulation resistance R _D becomes larger than 30,000 cmΩ.

When the area of the radio wave is imprinted in the longitudinal direction of the string on the conductive film divided in one direction in the string shape, the effect of the above-described conductive wire film cannot be expected and the same characteristics as in the continuous conductive film are obtained.

In order to obtain the same radio wave absorption characteristics as the strip-shaped conductive film for the electromagnetic field in either direction, the conductive film is set in a matrix. In the matrix shape, the above-mentioned one-way line conditions must be satisfied.

Next, as a preferred embodiment of the radio wave absorbing panel according to the present invention, as shown in Fig. 1, a conductive film having a function of reflecting radio waves almost 100% is formed on one of the insulating substrates constituting the panel, and the other insulation. Describes a panel on which a conductive film is formed which partially reflects, transmits, and partially absorbs radio waves, and at least one insulating substrate is formed between these two substrates with a matrix conductive film formed on the surface thereof. .

In this kind of radio wave absorbing panel, the thickness of the air layer can be reduced to about 1/2 compared to the case where an insulating substrate having a function of partially reflecting, transmitting, and partially absorbing radio waves is disposed all over the outer surface of the panel. In addition, the effect of the insulating substrate on which the strip-shaped or matrix-type conductive film is formed can be equivalent to twice the effect of such a substrate.

The sheet resistivity R _BM of the continuous conductive film having a function of reflecting radio waves almost 100% is set to 1 mW / square to 30 mV / square. In particular, the optical sheet resistivity R _BM is 5 kV / square to 20 kV / square. However, a conductive film having a low sheet resistivity R _BM can be used when no light transmittance is necessary, whereby a more significant effect can be obtained.

The sheet resistivity R _BM of the continuous conductive film having a function of partially reflecting and transmitting and partially absorbing radio waves is set to 50 mW / square to 3000 mV / square. In particular, the optical sheet resistivity R _BM is 200 kV / square to 1500 kV / square.

In order to apply the radio wave absorbing panel according to the present invention to a window of a building, it is necessary to use a transparent substrate against visible light as an insulating substrate, and transparent pane is suitable. In addition, a conductive film transparent to light is also used for the conductive film formed on the insulating substrate. In particular, in order to lower the sheet resistivity of the stripe or matrix type conductive film and to maintain light transmittance, the film material should be selected from a limited range of both. As a film material capable of realizing such a function, for example, a transparent conductive film mainly composed of SnO ₂ or In ₂ O ₃ or a metal film composed mainly of Ag, Au, Cu or Al is suitable.

These conducting films or metal films, in addition to radio wave absorption, reflect near-ultraviolet rays of sunlight and have a warm heat radiation function, thus saving energy in indoor air conditioners when the panel is used as a glass window.

In order to ensure the durability of the film, when a film of these films is used, particularly a metal film mainly composed of Ag, Au, Cu, or Al, a resin is interposed between a multilayer glass or a glass substrate prepared by enclosing dry air between glass substrates. Coated glass prepared by the above can be used. In order to impart radio wave absorption by using dry air or resin, the thickness of the air layer, the thickness of the glass substrate, and the thickness of the resin layer are set based on the conditions described above.

Hereinafter, the Example of this invention is described characteristically with a comparative example.

First embodiment

 Nitrogen oxide CrOxNy films were formed into sheets of soda-lime silica glass having a thickness of 4 nm by injecting 90 mol% of nitrogen gas and 10 mol% of oxygen using a linear sputtering device and reacting sputtering using a Cr metal target. Is formed. The thickness of this film is about 40 nm and the sheet resistivity of the film is about 400 GPa / square.

Next, a film of ZnO, Ag and ZnO is sequentially formed from the substrate surface on the soda-lime silica glass substrate having a thickness of 4 mm by a linear sputtering apparatus to form an Ag film. The linear sputtering apparatus is adjusted so that the thickness of each film is 40 nm, 15 nm, and 40 nm. ZnO film has a role to maintain the durability of Ag film. The sheet resistivity of the obtained film is about 5 GPa / square.

In addition, by using the same line sputtering apparatus, a thin stainless steel mask mask having a thickness of about 0.5 mm having a square hole having a distance of 4 mm and a side length of 5 cm between adjacent holes was prepared to prepare a soda lime silica having a thickness of 4 mm. Placed on a glass substrate, films of ZnO, Ag and ZnO are formed in turn from the surface of the glass substrate to adjust the line sputtering apparatus so that the films are 40 nm, 15 nm and 40 nm in thickness, respectively.

The mask is then removed to form a 5 cm square transparent ZnO / Ag / ZnO film in a matrix on the substrate. The sheet resistivity of a film is about 5 kPa / square, and the insulation resistance between adjacent films is 20 kPa or more.

Then, these three glass substrates were cut into a square having a length of 120 cm and 4 mm glass / CrOxNy: 0.6 cm Air layer: ZnO / Ag / ZnO matrix film / 4 mm Glass: 2.4 cm Air layer: ZnO / Ag / ZnO film / 4 It is used to construct a laminated plate of mm glass structure.

When measuring the radio wave reflections and transmissions of 200 MHz to 1 GHz for this laminate, it was found that at about 500 MHz the reflections are reduced and excitation is a region where strong resonance absorption occurs.

The calculation results of the radio wave reflectance and absorption characteristics obtained using the above-described near-theory theory for this panel are shown in FIG.

Comparative Example 1

The laminated plate was manufactured by replacing the glass substrate having a thickness of 4 nm of the first embodiment in which the matrix type Ag film was formed thereon with the glass substrate without the film. Measure As a result, although there was a decrease in reflectance and an increase in permeability near 1㎓, there was no resonance absorption below 1㎓.

In the theoretical calculation results of radio wave reflectance and permeability obtained for this structure, there was a resonance absorption near about 1.2 Hz as shown in FIG.

In order to increase resonance absorption near the 500 MHz frequency as in the first embodiment, it is necessary to increase the 2.5 cm thick air layer to 10 cm.

Second embodiment

About 60 nm thick ITO on a 4 mm-thick soda-lime silica glass substrate by injecting a tin indium oxide (ITO) sintered target into a line sputtering apparatus and adding 20 mol% oxygen to argon. Form a film. The film forming conditions are adjusted so that the sheet resistivity of the film is about 400 GPa / square.

The laminated plate is manufactured by substituting this substrate instead of the substrate of the first embodiment in which a CrOxNy film is formed thereon, and measuring the 1 GHz radio wave reflectance and radio wave transmittance from 200 MHz to the laminate. As a result, this laminate had substantially the same characteristics as in the first embodiment.

Third embodiment

Using a linear sputtering apparatus, SnO ₂ , Ag and SnO ₂ films are formed on a 4 mm thick soda lime silica glass substrate. The film thickness was adjusted to 40 nm, 15 nm, and 40 nm, respectively, and the film of sheet resistivity 5 mA / square was obtained.

The film surface of this glass substrate is marked by a checkerboard form using steel needles, and is thereby divided into squares of about 20 cm in length. When the divided area is observed with an optical microscope, it is observed that the film is divided into lines having a width of 200 µm or less. Thus, the electrical resistance between the divided adjacent conductive films is generally about 50 kΩ or more. The laminated board was manufactured by substituting the glass substrate having a 20 cm square matrix film formed thereon instead of the glass substrate of the first embodiment in which the matrix film of ZnO / Ag / ZnO was formed thereon. Radio wave reflectance and radio wave permeability were measured. The result was a resonance absorption slightly weaker than that of the first embodiment at around 250 MHz.

Comparative Example 2

ITO, Ag and ITO films were formed on glass substrates using a linear sputtering apparatus. The thickness of the film was adjusted to 40 nm, 15 nm and 40 nm, respectively, and a film with a sheet resistivity of about 5 GPa / square was obtained.

In the same manner as in the third embodiment, the film surface was marked using a steel needle in the form of a check board, thereby dividing the film into a square having a length of about 20 cm. Thus, the electrical resistivity between the divided adjacent conductive films was 50 kPa (about 1000 cmPa as R _D ).

The laminated plate was manufactured by substituting this glass substrate having a 20 cm square matrix film formed thereon instead of the glass substrate of the first embodiment having a matrix of ZnO / Ag / ZnO films formed thereon. ㎓ Measure radio wave reflectance and transmittance. The results showed a slight decrease in reflectance near the frequency of 250 MHz, but no resonance absorption.

Fourth embodiment

The chromium oxide film CrNxOy having a sheet resistivity of about 400 GPa / square mentioned in the first embodiment was formed on a 10 mm thick glass, cut into squares having a side length of 80 cm, and placed perpendicular to the bottom surface.

Then, a 1 cm long styrofoam cube is used as a space and attached to the film surface of this glass at a grid point spaced about 30 cm apart.

This is a colorless float glass with a thickness of 4 mm coated with a transparent conductive film composed of SnO ₂ film with a sheet resistivity of about 10 Ω / □ treated with a fluorine film at a thickness of about 300 nm. It is 20 cm wide and 180 cm long. It was cut and aligned closely to the plastic sheet in the longitudinal direction to fix a panel of 180 cm in length.

The panel is placed vertically, facing the 10 mm thick glass, with a styrofoam spacer in between.

In addition, the panel was sandwiched and placed to be in equilibrium with another panel having a stretched aluminum foil having a thickness of 15 μm, so that the thickness of the air layer formed between the panels could be varied.

The reflectance was then measured in the frequency region 50 MHz to 500 MHz with the linearly polarized radio wave directed at the 10 mm thick glass surface on the laminate thus constructed.

When the polarization of the radio wave region becomes horizontal and the thickness of the variable air layer is about 15 cm, the reflectivity decreases and strong resonance absorption occurs at about 100 MHz.

Comparative Example 3

The reflectance was substantially 100% at frequencies 50 MHz to 500 MHz when the radio wave in the vertically polarized region was directed to the laminate of the fourth embodiment.

Comparative Example 4

From the laminated plate structure of the fourth embodiment, a panel made by aligning 20 cm by 180 cm glass pieces coated with a transparent conductive film was removed, and the air absorption was varied to vary the thickness of the air layer. The search was about 100 MHz. As a result, it was found that it is essential to make the thickness of the air layer about 70 cm.

Fifth Embodiment

4mm thick soda-lime silica glass substrate coated with continuous ITO film with sheet resistivity of about 400Ω / □ and SnO ₂ / Ag / SnO ₂ film with sheet resistivity of about 5Ω / □ are formed to make marks with steel needles 18mm thick soda-lime silica glass substrate coated with a transparent conductive film made of 5cm square matrix and 4mm thick coated with continuous ZnO / Ag / ZnO / Ag / ZnO film with a sheet resistivity of about 3Ω / □ 4 mm glass / ITO film: 0.36 mm resin: segmented SnO ₂ / Ag / SnO ₂ film / 18 mm glass: 0.36 mm resin: ZnO / Ag A laminated panel panel of a / ZnO / Ag / ZnO film / 4 mm glass structure was formed.

The radio wave was directed to the surface of the glass substrate coated with the ITO film on the laminate and the radio wave reflectance and radio wave transmittance of 400 MHz to 1.5 GHz were measured. As a result, it was found that resonance absorption occurred around 600 MHz.

Comparative Example 5

The laminated glass is constructed by using an 18 mm thick soda lime silica glass substrate, on which nothing is applied, in place of the 18 mm thick soda lime silica glass substrate in which the matrix of the transparent conductive film is formed in the laminated structure of the fifth embodiment.

When the radio wave was directed to the surface of the glass substrate coated with ITO film on this laminated panel and the 400 MHz to 1.5 GHz radio wave reflectance and radio wave permeability were measured, the resonance absorption occurred around 1.2 dB.

As described above, the present invention increases the relative permittivity of the radio wave absorption panel and makes it possible to obtain a thin radio wave absorption panel having excellent light transmission as well as excellent light transmission. Therefore, the radio wave absorbing panel according to the present invention is ideal as a panel installed as a glass window of a building.

Claims (10)

At least two insulating substrates each having a continuous conductive film formed on at least one surface thereof and disposed in equilibrium with a predetermined distance therebetween; A radio wave absorbing panel, comprising at least one insulating substrate disposed in parallel with these insulating substrates and having a stripe or matrix conductive film formed thereon. The sheet resistivity of the continuous conductive film is 1 Ω / □ to 3000 Ω / □, and each width and sheet resistivity of the conductive film arranged in a row are represented by Hcm and R _BM Ω / □, respectively. The insulation resistance of the insulation substrate on which the strip-shaped conductive film is formed is expressed as R _D cmΩ, where H, R _BM and R _D are 1 cm ≤ H ≤ 50 cm, 1 Ω / □ ≤R _BM ≤40Ω / □, R _D ≥30,000 cm Radio wave absorption panel characterized in that. The sheet resistivity of the continuous conductive film is 1 Ω / □ to 3000 Ω / □, and the width, length and sheet resistivity of each conductive film arranged in a matrix form are Hcm, Vcm, and R _BM Ω / When the insulation resistance of the insulating substrate on which the matrix type conductive film is formed is represented by R _D cmΩ, H, V, R _BM , and R _D are 1 cm ≤ H ≤ 50 cm, 1 cm ≤ V ≤ 50 cm, 1Ω / □ ≤R _BM ≤40Ω / □ R _D ≥30,000 cm Radio wave absorption panel characterized in that. The sheet resistivity of the continuous conductive film formed on the surface of one insulating substrate is 1 GPa / □ to 30 GPa / □, and the sheet resistivity of the continuous conductive film formed on the surface of the other insulating substrate is 50 GPa / □ to 3000 / □, the width and sheet resistivity of each conductive film arranged in a row shape are indicated by Hcm and R _BM Ω / □, respectively, and the insulation resistance of the insulating substrate on which the conductive film arranged in a line shape is formed is R _D cm When denoted by H, H, R _BM and R _D are 1 cm ≤ H ≤ 50 cm, 1 Ω / □ ≤R _BM ≤40Ω / □, R _D ≥30,000 cm Radio wave absorption panel characterized in that. The sheet resistivity of the continuous conductive film formed on the surface of one insulating substrate is 1 GPa / □ to 30 GPa / □, and the sheet resistivity of the continuous conductive film formed on the surface of the other insulating substrate is 50 GPa / □ to 3000Ω / □, and a width, the length and the sheet resistivity of each conductive film arranged in a matrix and displayed in each H㎝, V㎝ and R _BM Ω / □, the insulation of an insulating substrate a conductive film arranged in a matrix formed When the resistance is expressed in R _D cmΩ, H, V, R _BM and R _D are 1 cm ≤ H ≤ 50 cm, 1 cm ≤ V ≤ 50 cm, 1 Ω / □ ≤R _BM ≤40Ω / □, R _D ≥30,000 cm Radio wave absorption panel characterized in that. The transparent conductive film according to any one of claims 1 to 5, wherein the transparent plate glass is used as the insulating substrate and the strip or matrix conductive film is mainly composed of SnO ₂ or In ₂ O ₃ or mainly Ag, Au, Cu, or Radio wave absorption panel characterized by a metal film composed of Al. The method according to any one of claims 1 to 5, wherein dry air is sealed in a space between at least two insulating substrates and at least one insulating substrate having conductive films arranged in a stripe or matrix form on the surface thereof. Featuring a radio wave absorption panel. The radio wave according to any one of claims 1 to 5, wherein the resin is sealed in a space between at least two insulating substrates and an insulating substrate on which a conductive film arranged in a strip or matrix form is formed on the surface thereof. Absorption panel. 7. The radio wave absorbing panel according to claim 6, wherein dry air is sealed in a space between at least two insulating substrates and at least one insulating substrate having conductive films arranged in a stripe or matrix form on the surface thereof. . The radio wave absorbing panel according to claim 6, wherein the resin is sealed in a space between the at least two insulating substrates and the insulating substrate having conductive films arranged in a row or matrix form on the surface thereof.