JPH11330774A - Electromagnetic wave shielding body - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve the electromagnetic wave shielding performance and the see-through property of an image display device by providing a thin-film layer which consists of a transparent conductive material and a pattern layer consisting of a conductive material. SOLUTION: A plurality of straight line groups, that do not cross one another or a mesh-shaped pattern where the straight line groups cross form a continuous conductive layer in which region consisting of a low-resistance conductive material is continuous over the entire surface of a shielding body. Since the generation of a moire fringe or the like which adversely affects a display image can be suppressed, mutually discrete figures whose surface area is equal to or less than 1 cm2 can be formed. No pattern can be seen in those with a line width 10 of 5-20 μm and a pitch of 50-200 μm, thus preventing a display image from being affected. Either glass or resin can be used for a transparent base. With the transparent resin base, the resins can be formed in a film or sheet shape by extrusion molding or the like. By randomly changing the shape and a pitch 11 of the patterns, the interference with the scanning line fringe, stripe, or the like of the display image with a periodical property can be suppressed, thus highly maintaining the quality of the display image.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electromagnetic wave shield. More specifically, the present invention relates to an electromagnetic wave shield having excellent electromagnetic wave shielding properties as well as excellent transparency, and which is suitably used for an electromagnetic wave shielding filter of an image display device.

[0002]

2. Description of the Related Art Conventionally, as a method of shielding an electromagnetic wave while maintaining transparency, a method using a conductive mesh obtained by etching a conductive fiber or a metal deposition film, a method using indium tin oxide (hereinafter abbreviated as ITO), and the like. There is known a method of using a transparent conductive thin film obtained by evaporating a substance by sputtering or the like. However, CR
When an electromagnetic wave shield made of a conductive mesh is used for an image display device such as a plasma display or a plasma display, the luminance value is significantly reduced, and the power consumption is increased, especially in a plasma display in which it is difficult to increase the luminance, and the panel is short. Inviting longer life, etc.
Not preferred. At the same time, there is also a problem that the displayed image is significantly deteriorated, such as narrowing of the viewing angle and occurrence of moire.

On the other hand, in the method using a transparent conductive thin film, although the deterioration of a displayed image is relatively small, the shielding property against electromagnetic waves is insufficient, and it is necessary to increase the film thickness in order to obtain a sufficient shielding property. There is a problem that the brightness value is reduced. Attempts have been made to solve these problems by using a low-resistance thin film containing a highly conductive metal such as Ag, but this requires a complicated vapor deposition process, resulting in an increase in cost. In addition, since a highly reflective highly conductive metal causes a problem of increasing the reflectance, the emergence of a technology for shielding electromagnetic waves simply, at a high efficiency and at a low cost without deteriorating a display image is awaited. I was

[0004]

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems in the prior art relating to an electromagnetic wave shield, and has excellent electromagnetic wave shielding properties as well as excellent transparency. It is an object of the present invention to provide an electromagnetic wave shield suitably used for a shielding filter or the like.

[0005]

The gist of the present invention is to provide an electromagnetic wave shield characterized in that a thin film layer made of a transparent conductive material and a pattern layer made of a conductive material are provided on the surface of a transparent substrate. Exists.

[0006]

BEST MODE FOR CARRYING OUT THE INVENTION As the transparent substrate used in the present invention, any of glass and resin can be used, but it is particularly preferable to use a transparent resin which is lightweight and has excellent workability.
Specifically, polyester resin, polycarbonate resin, poly (meth) acrylate resin, alicyclic polyolefin resin, polystyrene resin, polyvinyl chloride resin, polyvinyl acetate resin, polyarylate resin And thermoplastic resins such as polyethersulfone resins.

[0007] The transparent resin substrate in the present invention can be formed into a film by a known method such as extrusion molding, calender molding, compression molding, injection molding or the like, or a method of casting by dissolving in a solvent. Molded into a shape or sheet, the thickness is 10μm
About 5 mm. In addition, these transparent resin base materials include
Commonly used additives, for example, phenolic,
A phosphorus-based antioxidant, a halogen-based or phosphorus-based flame retardant, a heat stabilizer, an ultraviolet absorber, an infrared absorber, a lubricant, an antistatic agent, etc. may be added and coated.

As a thin film layer made of a transparent conductive material used in the present invention, typically, metal oxides such as tin oxide, indium oxide, antimony tin oxide, aluminum zinc oxide, tin fluoride oxide, gold, silver, Examples include a thin film made of a metal such as a platinum-palladium alloy. Coating methods include thin film using dry process such as resistance heating evaporation, sputtering, ion plating, chemical vapor deposition, spray coating of conductive fine particle dispersion, spin coating, dip coating, Mayer bar coating, roll coating, etc. Any of thin films using a wet process can be used.

In particular, a low-resistance,
In order to obtain a uniform thin film layer, it is preferable to use a dry process. The thickness of the thin film layer made of a transparent conductive material varies depending on the required physical properties, applications, and the like.
It is 0 to 500 nm, more preferably 50 to 300 nm. When forming a thin film by sputtering or the like,
In order to improve the adhesiveness to the transparent substrate, it is desirable to coat the base coat agent on the surface on which the thin film is to be formed in advance.

In the present invention, the pattern made of a conductive substance is composed of a simple metal such as gold, silver, platinum, palladium, nickel, copper, or aluminum, or a carbon material such as carbon black or graphite. The line width is 5 to 500 μm, more preferably 5 to 100 μm, still more preferably 5 to 25 μm, and the pattern pitch is 10 to 50 μm.
The thickness is 00 μm, more preferably 30 to 3000 μm, and still more preferably 50 to 2000 μm.

The height of these lines is 2 to 15 μm.
It is preferable from the viewpoint of electromagnetic wave shielding properties. The method of forming the pattern is not particularly limited, and printing of a paint made of a conductive paste or a conductive ink, sticking of a conductive fiber, etching of a deposited film, and the like can be used. Screen printing of a conductive paint made of is most preferable because of excellent pattern uniformity, controllability, and productivity. Here, the above-mentioned materials are used as the conductive fine powder, and their average particle size is usually
It is about 0.01 to 10 μm.

Further, as the binder resin, an acrylic resin, a polyester resin, a polyvinyl chloride resin or the like is used, and the content of the conductive fine powder in the conductive portion is based on the total amount with the binder resin. It is about 75 to 95% by weight. Screen printing is performed by, for example, 75 to 95% by weight of the conductive fine powder, 25 to 5% of the binder resin.
% By weight and 100 parts by weight thereof, toluene,
From 3 to 65 parts by weight of a solvent such as xylene, methyl ethyl ketone, or cyclohexanone, and 1 to 10 parts by weight of a dispersant such as an anionic or nonionic surfactant, is used as a solvent.
~ 100,000 cps, preferably 3000-2000
A conductive paint having a viscosity of about 0 cps is prepared, and a printing is performed on the transparent base material by using a screen having a resist coating obtained by printing a pattern such as the square of the line width and the pattern pitch. .

At this time, prior to printing, a corona discharge treatment, a plasma discharge treatment, a flame treatment,
Known surface treatments such as a chemical treatment and a primer treatment can also be performed. Either the thin film or the pattern may be provided first. In the present invention, the pattern made of a conductive material used is composed of one or more straight lines, or curves, as long as it has the line width and the pitch,
There is no particular limitation in this range because the pattern is not visible and there is no adverse effect on the displayed image.

One example is a mesh-like pattern obtained by intersecting a plurality of non-intersecting straight line groups or straight line groups as shown in FIGS. 1 and 2. The mesh-like pattern is made of a low-resistance conductive material. Since the conductive region forms a continuous conductive layer over the entire surface of the shield, it is particularly suitable for obtaining a shield having high electromagnetic wave shielding properties. Of course, not only a straight line but also a curve group may be used.

In order to suppress the occurrence of moire fringes or the like which adversely affect the displayed image, it is preferable to use mutually discrete figures having a surface area of 1 cm ² or less. The figure referred to here is, for example, a pattern composed of a large number of squares or circles as shown in FIGS. 3, 4, 5, and 6, and more specifically, a large number of parallel straight lines and intersecting them. A triangle, by at least two of a number of parallel straight lines,
Or, in addition to those in which squares such as squares, rectangles, and rhombuses are drawn adjacent to each other, for example, each of the turtle-shaped squares may be drawn adjacent to each other. Or, each of the circles includes one drawn independently.

In particular, by randomly changing the shape and pitch of these patterns, it is possible to suppress the interference of the display image having periodicity with scanning line stripes, stripes, and the like, and to keep the quality of the display image high. is there. In addition, these patterns play a role as a kind of antenna against the incident electromagnetic wave, and express the electromagnetic wave shielding effect, so the size,
By devising the shape, the characteristics can be changed so as to shield a specific frequency band more.

In the electromagnetic wave shield of the present invention, it is preferable that a protective film is further laminated on a layer or pattern made of a conductive substance formed on the surface of the transparent base material. The resins mentioned as materials for the resin base material are preferably used, and these resins are dry-laminated,
Lamination is performed by a known method such as wet lamination or extrusion lamination.

The electromagnetic wave shield of the present invention obtained as described above has a coating layer made of a transparent conductive material having a high resistivity and insufficient electromagnetic wave shielding properties by itself.
The average resistivity of the conductive layer as a whole, even if the pattern is made of a conductive material with high electromagnetic wave shielding and has a small pattern that has little effect on surface brightness or image quality due to ohmic contact. Has the effect of significantly reducing
It is possible to exhibit high electromagnetic wave shielding properties.

Therefore, it is possible to provide an electromagnetic wave shield having a high electromagnetic wave shielding property while suppressing the adverse effect on the transmitted image while having a high electromagnetic wave shielding property, and having a high transparency. display,
As an electromagnetic wave shielding filter used for an image display device such as an electroluminescence display and a liquid crystal display, it can be particularly suitably used. Further, a near-infrared absorbing layer, an antireflection layer, an anti-scratch layer, and the like can be appropriately laminated to provide a more sophisticated filter.

[0020]

EXAMPLES Hereinafter, the present invention will be described in more detail with reference to examples, but the present invention is not limited to the following examples unless it exceeds the gist.

Example 1 A polyethylene terephthalate resin film (thickness 100
μm), indium oxide (a target manufactured by Kojundo Chemical Co., Ltd.) was deposited by sputtering to obtain a coat layer made of a transparent conductive material having a total light transmittance of 80%. A stainless steel wire mesh screen (aperture 25 μm) was applied to the surface of the coat layer using a screen printing machine (manufactured by Microtec).
m), by screen-printing a special gold ink manufactured by DuPont containing gold fine powder, to obtain a line width of 15 μm.
m, a pattern pitch of 1000 μm, a line height of 5 μm, and a pattern (FIG. 4) made of a conductive material formed by dispersing and drawing a square pattern.

Further, a protective film made of polyethylene terephthalate resin and having a thickness of 100 μm was laminated on the conductive layer to obtain an electromagnetic wave shield. With respect to the obtained electromagnetic wave shielding body, the electromagnetic wave shielding property and the transparency were evaluated.
It was shown to. In addition, the electromagnetic wave shielding property has a frequency of 30 to 500.
The attenuation (dB) in the MHz range was measured. In addition, see through the electromagnetic wave shield that stands up 1m away visually,
The case where the pattern could not be confirmed was evaluated as ○, and the case where it could be confirmed was evaluated as ×.

Example 2 Silver ink (JELCO manufactured by Jujo Kako) containing fine silver powder
M SH-1) was used, and a square pattern was formed with a line width of 20 μm.
m, a pattern pitch of 1000 μm, and a line height of 3 μm, except that the electromagnetic wave shield was manufactured in the same manner as in Example 1,
The electromagnetic wave shielding property and the transparency were measured, and the results are shown in Table 1.

Embodiment 3 In addition to providing a mesh made up of a straight line group having a line width of 12 μm, a pitch of 1000 μm, and a line height of 5 μm, and a straight line group having the same shape and orthogonal to this, as a pattern made of a conductive material In the same manner as in Example 1, an electromagnetic wave shielding body was manufactured, and the electromagnetic wave shielding property and the transparency were measured. The results are shown in Table 1.

Comparative Example 1 An electromagnetic wave shield was manufactured in the same manner as in Example 1 except that the pattern made of a conductive material was not provided, and the electromagnetic wave shield and the transparency were measured. The results are shown in Table 1. Indicated. Comparative Example 2 A square pattern having a line width of 100 μm and a pattern pitch of about 6670 μm was provided without performing sputtering of indium tin oxide (a target manufactured by Kojundo Chemical Co., Ltd.). Manufacturing shields,
The electromagnetic wave shielding property and the transparency were measured, and the results are shown in Table 1.

[0026]

[Table 1]

[0027]

According to the present invention, it is possible to provide an electromagnetic wave shielding body which is excellent not only in electromagnetic wave shielding properties but also in transparency, and is suitably used for an electromagnetic wave shielding filter of an image display device.

[Brief description of the drawings]

FIG. 1 shows an example of a pattern made of a conductive material.

FIG. 2 shows an example of a pattern made of a conductive material.

FIG. 3 shows an example of a pattern made of a conductive material.

FIG. 4 shows an example of a pattern made of a conductive material.

FIG. 5 shows an example of a pattern made of a conductive material.

FIG. 6 shows an example of a pattern made of a conductive substance.

[Explanation of symbols]

 10 line width 11 pitch

Claims (10)

[Claims] 1. An electromagnetic wave shield comprising a transparent base material surface provided with a thin film layer made of a transparent conductive material and a pattern layer made of a conductive material. 2. The electromagnetic wave shield according to claim 1, wherein the transparent substrate is a transparent resin. 3. The thin film layer made of a transparent conductive material is a film formed by depositing a transparent conductive material.
2. The electromagnetic wave shield according to claim 1. 4. The transparent conductive substance is at least one selected from the group consisting of metal oxides consisting of tin oxide, indium tin oxide, antimony tin oxide, aluminum zinc oxide, and tin fluorinated oxide. 4. The electromagnetic wave shield according to any one of 3. 5. A pattern layer made of a conductive substance is coated with a paint containing a conductive fine powder and a binder resin so as to have a line width of 5 to 20.
2. A printing method according to claim 1, wherein the printing is performed on a straight line or a curved line with a pitch of 50 to 2000 .mu.m.
5. The electromagnetic wave shield according to any one of items 1 to 4. 6. A pattern layer made of a conductive substance is coated with a paint containing a conductive fine powder and a binder resin to have a line width of 5 to 20.
[mu] m, the electromagnetic wave shielding member according to claims 1, characterized in that those provided by printing a pitch pattern as discrete surface area 1 cm ² following figures together as 50 to 2000 m 4. 7. The electromagnetic wave shield according to claim 5, wherein the pattern layer made of a conductive substance is formed by screen printing. 8. The electromagnetic wave shield according to claim 5, wherein the conductive fine powder is at least one selected from the group consisting of gold, silver, platinum, palladium, and nickel. 9. The electromagnetic wave shielding body according to claim 1, wherein a protective layer is further laminated on the thin film layer made of a conductive substance and the pattern layer. 10. The electromagnetic wave shield according to claim 1, wherein the electromagnetic wave shield is an electromagnetic wave shield filter for an image display device.