JP2003202810A - Electromagnetic wave shield filter for display, filter for plasma display panel, and plasma display panel display - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an electromagnetic shield filter for a display which has a superior electromagnetic wave shielding property for an electromagnetic wave shield filter used for a display, etc., and also has high transmissivity to emitted light and low reflectivity to external light at a low cost and with simple constitution. <P>SOLUTION: The electromagnetic wave shield filter comprises an absorption type circular polarization plate 1, an electromagnetic wave shield material 2, and a selective reflection type circular polarization plate 3 which reflects circular polarized light in the same direction as circular polarized light that the absorption type circular polarization plate 1 absorbs and transmits circular polarized light in a reverse direction thereto in order from the observer side of a display 4. <P>COPYRIGHT: (C)2003,JPO

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 filter for a display device, a plasma display panel (hereinafter referred to as PDP) filter to which the filter is applied, and a PDP display device using this filter.

[0002]

2. Description of the Related Art Display display devices such as PDPs, CRTs, and field emission displays have large and small sizes due to their operating principles, but unnecessary electromagnetic waves are emitted, which not only cause malfunctions of peripheral devices and noise sources. There is also concern about the effects on the human body. Therefore, it is necessary to provide some electromagnetic wave shield filter and cut them.

The electromagnetic wave shield of a normal device is achieved by surrounding them with a conductor, but in the case of a display, it must be an electromagnetic wave shield filter having both transparency and conductivity. For example, a transparent conductive film such as an indium tin oxide thin film is one example, but the surface resistance is at most about several tens Ω / □, which is insufficient to shield the electromagnetic waves of high intensity radiated from the PDP or the like. .

The electromagnetic waves radiated from such equipment are VCCI (Voluntary Control).
l Council for Interferc
eby data processing equip
ment electronic office ma
Chinese) and FCC (Federal Commu)
There is a regulation set by the Nation Commission. Although the frequency range of radiated electromagnetic waves covered by these regulations is 30 MHz to 1 GHz, problems such as becoming a noise source of home video also occur with respect to electromagnetic waves in the lower frequency region, and a wider range of frequencies is used. In the band, a filter having an excellent electromagnetic wave shielding property is required.

In response to such requirements, an excellent electromagnetic wave shielding property, particularly a magnetic field shielding property at low frequencies is excellent, and in addition, a conductive mesh filter is used to ensure transparency. That is, the conductive mesh has a thick conductive layer of the order of μm,
Particularly, the electromagnetic wave shielding property in the low frequency region is good, and an electromagnetic wave shielding filter having a low resistance of 1 Ω / □ or less, particularly 0.1 Ω / □ or less can be easily realized.

However, in the case of a mesh filter,
It is necessary to make the wire diameter of the mesh as thin as possible in order to arrange it on the front surface of the display so as not to impair its visibility. In addition, moire may occur between the display pixels and the visibility may be significantly reduced.
For example, a fiber type mesh obtained by plating a metal on a polyester fiber is inexpensive and has a good electromagnetic wave shielding property, but has a limitation in thinning the wire diameter, and significantly reduces the visibility of the display. For this reason, for example, it is necessary to manufacture an extremely fine mesh in a large area by making full use of photolithography technology to which a semiconductor manufacturing technology is applied, which is an extremely expensive electromagnetic wave shield filter.

Further, since the above-mentioned mesh filter basically uses a metal mesh such as copper, reflection of outside light due to metallic luster is remarkable, visibility is remarkably deteriorated due to reflection of indoor lighting, and only fine lines are formed. Then it cannot be reduced. Therefore, it is necessary to further perform the blackening treatment on the surface, which further increases the manufacturing cost. Further, although such processing can suppress external light reflection to some extent, it is not easy to realize a higher bright room contrast.

In addition to the mesh filter, there is a method of using a metal thin film as a means for imparting an electromagnetic wave shielding property. Generally, metals are not transparent to visible light and cannot be used for display applications, but when the film thickness is several tens of nm or less, visible light is transmitted. Among them, silver has the highest electric conductivity among metals, and is a material having extremely excellent visible light transmittance, and thus it can satisfy both transparency and conductivity at the same time. However, dozens of n
Even a thin film having a thickness of m or less has a high visible light reflectance due to metal reflection and cannot be suitably used for display applications. For this reason, it is necessary to perform an optical design in consideration of antireflection of the silver thin film.

As a method for solving the above problems, for example, as disclosed in Japanese Patent Laid-Open No. 2000-98131, a method of alternately stacking high refractive index thin films and silver thin films has been proposed. By performing an optical design by appropriately selecting the refractive index of each layer, the film thickness, the configuration, the number of repeated layers, etc.
It is possible to simultaneously satisfy electrical conductivity, visible light transmittance, and low visible light reflectance. The optical design can be easily performed using commercially available optical design software based on the classical optical design method.

However, as described in Japanese Patent No. 3004222, the medium is air (refractive index = 1.0).
Even when the visible light reflectance is low, the visible light reflectance changes when an adjacent layer having a different refractive index is formed thereon. Further, when it is used as a display filter, a means for suppressing the reflection on the surface by bonding an antireflection layer or an antireflection film on the outermost surface is taken. If the interface reflection with the adjacent layer is large, the reflectance will eventually be high, and the filter will have a significantly poor visibility.

The surface resistance and other values are also designed to reduce the visible light reflectance, so that the degree of freedom in designing is naturally limited. In general, when performing an optical design that suppresses such interface reflection, it is necessary to reduce the thickness of the silver thin film or increase the number of repeated layers. In the former case, it is difficult to achieve sufficient electromagnetic wave shielding property with a simple structure, and in the latter case, not only the manufacturing cost is significantly high, but also a strict optical design and a highly accurate manufacturing process for reproducing it are required. Required.

As described above, according to the conventional technique, it is very difficult to inexpensively provide an electromagnetic wave shield filter which is excellent in electromagnetic wave shielding property, and is also excellent in transparency and low visible light reflection property. It was On the other hand, as a method of reducing the external light reflection of the display device filter, a method of forming an antireflection layer or an antiglare layer on the outermost surface, or a method of bonding a separately prepared film having those functions is generally adopted. There is. However, even if the reflection on the outermost surface can be reduced by such a method, the interface reflection between the electromagnetic wave shielding material and its adjacent layer cannot be reduced.

As a method of preventing interfacial reflection inside the display device or in each layer, a method of installing an absorption type circularly polarizing plate on the outermost surface has been proposed, for example, JP-A-7-14.
The application example is shown in Japanese Patent Laid-Open No. 2170, and JP-A-11-2
In Japanese Patent No. 42933, a proposal to apply to PDP is also made. In this proposal, the action of the absorptive circularly polarizing plate makes it possible to absorb all the external light reflection generated inside it.
In principle, about 50% of the emitted light from the display device itself is absorbed by the absorptive circularly polarizing plate, and there is a problem that the brightness of the display device is halved. However, it is known that about 50% of the emitted light is lost because the absorption type circularly polarizing plate has an extremely large effect of preventing the reflection of external light and improving the contrast.
There are many cases where this method is adopted.

In a liquid crystal display, Japanese Patent Laid-Open No. 10-30
As disclosed in Japanese Patent No. 1097, a cholesteric liquid crystal layer or a quarter-wave retardation plate is used, and the light of the backlight, which is normally absorbed by a linear polarizer, is transmitted to the absorption axis of the linear polarizing plate again. A technique for improving the brightness by converting into orthogonal linearly polarized light has also been proposed. In the case of a liquid crystal display, in principle, a linearly polarizing plate is left in a crossed nicols state with a liquid crystal cell sandwiched between them, so that the reflected light inside the device does not pose a problem. Therefore, it is possible to improve the brightness of the display by using the above technique. Furthermore, Japanese Patent Laid-Open No. 2001-215886 discloses a PDP.
There have been proposals for combining an absorption-type polarizer and a reflection-type polarizer.

However, in each case, these proposals are inventions made to reduce the reflection of external light inside the display device, and no mention is made of reflection prevention by the electromagnetic wave shield material. In addition, due to the principle of light emission, the PDP has a wavelength of 800 to 1,100 nm in addition to unnecessary electromagnetic waves.
Near infrared rays in the wavelength range of are also emitted at the same time. The near-infrared ray has no adverse effect on the human body and is not particularly regulated. However, since the near-infrared ray in this wavelength range is used as a remote controller for household appliances, it easily causes malfunctions of home electric appliances. Therefore, a function of transmitting visible light and cutting off near infrared rays must be added. Further, since Ne is used as the discharge gas, there is a problem in principle that orange emission light due to it is generated near the wavelength of 585 nm, and the color purity of the red emission of the PDP is significantly reduced. Is desirable.

[0016]

As described above, the high electromagnetic wave shielding properties required for various display devices, the high light-transmitting property, the low external light reflectivity, and the PDP's near-infrared cutting property and color At present, no means has been proposed for providing an electromagnetic wave shield filter for a display device that satisfies the improvement in purity at the same time with a simple structure and at a low cost.

In view of the above circumstances, the present invention shows an excellent electromagnetic wave shielding property in an electromagnetic wave shielding filter used for a display device such as a display, having a high transmittance of emitted light and a low reflectance of external light. It is an object of the present invention to provide an electromagnetic wave shield filter for a display device that can be realized with an inexpensive and relatively simple structure. Also,
An object of the present invention is to provide a PDP filter having an optimum function as a filter used in a PDP display device, and further to provide a PDP display device.

[0018]

Means for Solving the Problems As a result of intensive studies for solving the above problems, the present inventors have found that (1) an absorption type circularly polarizing plate and an electromagnetic wave shielding material are sequentially provided from the observer side of a display device. And a selective reflection type circularly polarizing plate that reflects circularly polarized light in the same direction as the circularly polarized light absorbed by the absorption type circularly polarizing plate and transmits circularly polarized light in the opposite direction. Therefore, it is possible to obtain an electromagnetic wave shield filter for a display device that can almost completely reduce the interface reflection due to the electromagnetic wave shield material and can efficiently radiate the light emitted from the display device to the observer side while minimizing the loss. And completed the present invention.

Further, in the electromagnetic wave shield filter for a display device described above, (2) a selective reflection type circularly polarizing plate is provided with a cholesteric liquid crystal layer exhibiting circular dichroism, so that the configuration is simpler. It turned out that the effect can be expressed. Further, (3) the electromagnetic wave shield material is made of a conductive mesh, and the line width is 20 μm or more and the aperture ratio is 85% or less, so that an electromagnetic wave shield mesh that is inexpensive and usually has poor visibility is suitable. Found to be available. (4) The electromagnetic wave shielding material includes one or more silver-based transparent conductor thin film layers, and the electromagnetic wave shielding material and the adjacent layer formed on the surface thereof have an interface reflectance of 0.5 to 30%. By configuring,
The structure of multilayer films including silver-based transparent conductor thin films can be simplified, and the degree of freedom in optical design is greatly expanded.
Moreover, it was found that the electromagnetic wave shielding property was extremely excellent.

The present inventors can also provide (5) a PDP filter equipped with the electromagnetic wave shielding filter having the above-mentioned configurations, in which case (6) a wavelength between the absorption type circularly polarizing plate and the display device is provided. By having a structure in which a layer for cutting near infrared rays of 850 to 1,000 nm is inserted, the near infrared ray cutting property can be easily imparted, and (7) the selective reflection type circularly polarizing plate has a wavelength range of 580 to 590 nm. Due to the absence of selective reflectivity, it was caused by Ne emission.
It was found that the light transmittance of orange emission light near 85 nm can be reduced by half, and the color purity of red emission can be improved.

Further, the inventors of the present invention have (8) a structure in which the front surface of the PDP is equipped with a front surface filter for PDP in which a transparent molded body installed via an air layer is provided with the PDP filter of each of the above structures. By doing, (9) PDP
A PDP display device provided with the PDP filter is provided by directly bonding the PDP filter of each of the above configurations to the front display glass portion of the main body via a transparent adhesive or a transparent adhesive. It turned out to be possible.

[0022]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below.
This will be described with reference to FIGS. 1 and 2. FIG. 1 is a schematic diagram showing a basic configuration in which an electromagnetic wave shield filter for a display device of the present invention is attached to a display device. In FIG. 1, the electromagnetic wave shield filter A for a display device includes an absorption type circular polarizing plate 1, an electromagnetic wave shielding material 2, and a selective reflection type circular polarizing plate 3 arranged in this order from the observer side of the display device 4. . It is preferable that each of the circular polarizing plates 1 and 3 is a perfect circular polarizing plate, but the circular polarizing plates 1 and 3 can be suitably used even if they are slightly deviated from the perfect circular polarizing plate to an elliptically polarizing plate. That is, each of the circular polarizing plates 1 and 3 includes an elliptical polarizing plate in addition to the perfect circular polarizing plate.

The absorptive circularly polarizing plate 1 is an absorptive linearly polarizing plate 1.
1 and the phase difference plate 12 in which the phase difference between the birefringent light is 1/4 wavelength
And is laminated. The absorption-type circularly polarizing plate 1 has the phase difference plate 12 with respect to the transmission axis of the absorption-type linearly polarizing plate 11.
Are formed by intersecting the optical axes of the light beams at an angle of 45 degrees or 135 degrees, and the angle determines whether right circularly polarized light or left circularly polarized light is absorbed. The selective reflection type circularly polarizing plate 3 is the absorption type circularly polarizing plate 1 described above.
Selectively reflects circularly polarized light in the same direction as the circularly polarized light absorbed by
It has a property of transmitting circularly polarized light in the opposite direction. Further, the electromagnetic wave shield material 2 is arranged between the absorption type circularly polarizing plate 1 and the selective reflection type circularly polarizing plate 3 described above.

The operation of the electromagnetic wave shield filter A having the above structure will be described in detail below with reference to FIG. In addition, here, a circularly polarizing plate that absorbs left circularly polarized light is adopted as the absorption type circularly polarizing plate 1, and accordingly, the selective reflection type circularly polarizing plate 3 is used.
An example in which a circularly polarizing plate that selectively reflects left circularly polarized light and transmits right circularly polarized light is adopted is shown in FIG. On the contrary, the absorptive circularly polarizing plate 1 adopts a circularly polarizing plate that absorbs right circularly polarized light,
Therefore, a circularly polarizing plate that selectively reflects right circularly polarized light and transmits left circularly polarized light may be adopted as the selective reflection circularly polarizing plate 3. Also in this case, the right circular polarized light and the left circular polarized light are exactly the same as the following description except that they are reversed.

First, the process of reflecting external light will be described. When the randomly polarized natural light enters the display device, it is first polarized and separated by the linear polarizing plate 11, one of which is absorbed and the other of which is transmitted to the retardation plate 12. At this point, about 50% of the external light is absorbed and becomes invisible to the observer as reflected light. The half of the linearly polarized light that has been transmitted is converted by the retardation plate 12 into right circularly polarized light. Phase difference plate 12
When the right-handed circularly polarized light 12 emitted from the laser light enters the electromagnetic wave shielding material 2, the circles that are regularly reflected at each interface having a refractive index higher than that of the retardation plate 12 or the transparent pressure-sensitive adhesive layer for bonding them. The polarized light has its phase inverted by 180 degrees, and is reflected as left-hand circularly polarized light having a reverse rotation to the incident right-hand circularly polarized light. For this reason, for example, in the case of a conductive mesh, the right circularly polarized light reflected by the metal line is converted again by the retardation plate 12 into linearly polarized light parallel to the absorption axis of the linearly polarizing plate 11, and the linearly polarizing plate 11 Is absorbed by. That is, the circularly polarizing plate 1
By arranging, the external light reflected by the electromagnetic wave shielding material 2 is absorbed by the circularly polarizing plate 1 regardless of the magnitude of its reflectance and becomes invisible to the observer.

The right-handed circularly polarized light, which is transmitted without being reflected by the electromagnetic wave shield material 2, is incident on the selective reflection type circularly polarizing plate 3.
Since the circularly polarizing plate 3 transmits right circularly polarized light, the light reaches the inside of the display device 4. Temporarily, display device 4
If the internal smoothness is good and the structure is such that the light regularly specularly reflects, the reflected right circularly polarized light is converted into left circularly polarized light by the same principle as described above. When the reflected left circularly polarized light is incident on the selective reflection circularly polarizing plate 3, it is reflected this time and returned to the inside of the display device 4 as the left circularly polarized light. Similarly, the left circularly polarized light specularly reflected inside the display device 4 is further phase-inverted to the right circularly polarized light again, and this time passes through the selective reflection type circularly polarizing plate 3 and is partially reflected by the electromagnetic wave shield material 2. Meanwhile, the light enters the absorptive circularly polarizing plate 1. The right-handed circularly polarized light passes through the absorptive circularly polarizing plate 1 and a part of the right-handed circularly polarized light comes into the eyes of the observer as external light reflection. In this case, the reflection by the electromagnetic wave shield material 2 where external light reflection becomes a problem is It is completely reduced and the reflected light entering the observer is greatly reduced.

The actual display device 4 has a complicated surface condition and structure. For example, in the case of PDP, partition walls are formed or phosphors are applied. Therefore, as described above, clean specular reflection does not occur, but diffuse reflection, internal absorption, or reflected light is depolarized by scattering and is in a state close to random polarization. In many cases. In this case, as schematically illustrated in FIG. 2, the reflected light returned to the observer side is further reduced, and the black display of the display device becomes tighter.
A display device with high bright room contrast can be obtained.

Next, regarding the light emitted from the display device,
The process will be explained. The emitted light emitted from the display device 4 is usually random natural light. The emitted light first enters the selective reflection circularly polarizing plate 3. At this time, polarized light is separated by the circularly polarizing plate 3, the right circularly polarized light enters the electromagnetic wave shielding material 2, is partially reflected, and most of the remaining part enters the absorption circularly polarizing plate 1 as the right circularly polarized light. In this case, right circularly polarized light can be transmitted as it is, and about 50% of the emitted light enters the eyes of the observer. on the other hand,
The left circularly polarized light selectively reflected by the circularly polarizing plate 3 is specularly reflected inside the display device 4 and converted into right circularly polarized light. After that, the light is transmitted through the absorptive circularly polarizing plate 1 in the same manner as above and enters the eyes of the observer.

Therefore, most of the emitted light can be delivered to the observer, although there is some loss in the electromagnetic wave shield material 2. However, like the previous explanation,
In an actual display device, depolarization due to scattered reflection occurs. For example, even if it is completely depolarized, half of it can pass through the selective reflection type circularly polarizing plate 3. Further, half of the reflected light repeats the same process as described above, and even if depolarized, the emitted light can be returned to some extent. Further, even if depolarized, if the degree of polarization is maintained to some extent, more light can be transmitted.

As described above, in the conventional method in which only the ordinary absorption type circularly polarizing plate is installed, the external light can be reduced, but
The emitted light is also absorbed by about half, and although the antireflection effect is obtained, there is a problem that the brightness is lowered. On the other hand, in the above-described present invention, the reflected light of the electromagnetic wave shielding material, which is most likely to lead to a reduction in visibility, can be completely reduced, and the reflected light inside the display device can be reduced by at least half or more. Absorption can be avoided as much as possible, and most of it can be guided to the observer side. If the display device itself emits polarized light, the effect of the present invention is further exerted.

Next, the material structure of the electromagnetic wave shield filter will be described. In the electromagnetic wave shield filter of the present invention, the respective members are actually formed by adhering them via a transparent adhesive or a transparent adhesive. In addition, these materials may be fused so as not to impair the polarization characteristics and electromagnetic wave shielding properties of each member, or may be installed with air layers separated, and the method is arbitrary. Further, a color adjustment layer, a near infrared ray cut layer, a barrier layer and the like may be added to any layer.

What is important in the present invention is to use, for these pressure-sensitive adhesive layers and other layers, those having small optical anisotropy, and those not ideal. If the inserted layer has optical anisotropy, the polarization state of light will change, and the effect of the present invention will be impaired. Since general pressure-sensitive adhesives and adhesives do not have optical anisotropy, any adhesive having excellent bonding strength and transparency can be suitably used. When the electromagnetic wave shielding material 2 and the selective reflection type circularly polarizing plate 3 are formed on a base material, for example, a glass plate, an epoxy resin substrate, a cellulose triacetate film, a norbornene resin film, or other commercially available products. A film having no optical anisotropy can be preferably used. Further, an antireflection layer may be formed on the outermost surface of the absorption type circularly polarizing plate 1, or a separately prepared antireflection film or antiglare film may be attached. In this case, it is clear from the above description using FIG. 2 that the effect of the present invention is not affected even if the antireflection film has optical anisotropy.

In the absorptive circularly polarizing plate 1, a suitable polarizing plate can be used as the absorptive linearly polarizing plate 11,
There is no particular limitation. In general, a polarizer obtained by dyeing a film made of a hydrophilic polymer such as polyvinyl alcohol with a dichroic dye or iodine and stretching the film in a boric acid aqueous solution by about 2 to 10 times is used. For example, “NPF” manufactured by Nitto Denko Corporation can be mentioned. Moreover, you may use what is obtained by orienting the liquid crystal or liquid crystal polymer containing a dichroic dye. The liquid crystal and the liquid crystal polymer are not limited, and nematic type, smectic type, cholesteric type, discotic type, and positive and negative materials thereof are used. You may use the polarizing element obtained by apply | coating on a base material film using the "lyotropic liquid crystal" by Optiva, Inc., etc.

Further, as the input / 4 wavelength retardation plate 12,
As the birefringent film having a retardation delay of ¼ wavelength of the visible light wavelength, a wide band λ / 4 plate having a wide retardation of ¼ wavelength in the visible light region may be used. Broadband λ / 4
The plate can be generally realized by a combination of birefringent films having different retardation values. Further, the retardation film may be a polymer film stretched and oriented. The polymer film used for the above retardation film is not particularly limited, but an optically transparent film with little alignment unevenness is preferably used. Examples thereof include polycarbonate, polyarylate, polysulfone, polyolefin-based, polyethylene terephthalate, polyethylene naphthalate, norbornene-based, acrylic-based, polystyrene-based, and cellulose-based. The polymer film may be coated or impregnated with the liquid crystal composition.

The electromagnetic wave shield material 2 may be any material as long as it can sufficiently shield the electromagnetic wave emitted from the display device 4, and among them, it is a conductive mesh made of metal or a multilayer film type including a silver-based transparent conductive thin film. Are preferred.

The conductive mesh has a line width of 20 μm or more, particularly 40 μm, in order to make the most of the features of the present invention.
As mentioned above, the aperture ratio is 85% or less, particularly 70% or less,
It is preferable to use an inexpensive conductive mesh which is not subjected to surface blackening treatment and which exhibits a metallic luster of high reflectance by itself. Specific examples thereof include, but are not limited to, a fiber mesh obtained by subjecting polyester fiber to metal plating, and a fiber mesh produced at low cost by a roll-to-roll method by screen printing. Even if such an inexpensive mesh having poor visibility is used, all the reflected light is absorbed by the polarizing plate by the configuration of the present invention. Therefore, there is no need to apply the photolithography technology, which requires high manufacturing cost, or to perform the surface blackening treatment. Such an expensive conductive mesh having good visibility can provide an electromagnetic wave shield filter having relatively good visibility without applying the present invention.

The multi-layer film type including the silver-based transparent conductor thin film may be of any type as long as it can sufficiently shield the electromagnetic waves emitted from the display device. Transparent thin film layer, transparent thin film layer / silver-based transparent conductor thin film layer / transparent thin film layer or silver-based transparent conductor thin film layer /
Examples thereof include a transparent thin film layer / silver-based transparent conductor thin film layer structure or a structure in which these are further repeated. These silver-based transparent conductor thin film layers and transparent thin film layers may all have the same composition or material, or may have different compositions. The silver-based transparent conductor thin film layer and the transparent thin film layer can be formed by a known thin film forming technique such as a vacuum process such as a vacuum deposition method, an ion plating method and a sputtering method, or a wet method.

Such a multilayer film type is optically designed such that the interface reflectance between the electromagnetic wave shielding material and the adjacent layer formed on the surface thereof is 0.5 to 30%. Is desirable. When the interface reflectance is less than 0.5%, an electromagnetic wave shield filter with good visibility can be obtained without applying the present invention, but the thickness of the silver-based transparent conductor thin film can be reduced or repeated. By increasing the number of layers,
High-precision optical design and film formation technology are required, and it is difficult to provide an inexpensive electromagnetic wave shield filter. Further, when the interface reflectance is more than 30%, the reflection of external light can be reduced, but the emitted light from the display device is also reflected, so that the emission intensity is reduced.

The reflectance referred to in the present invention is the JIS R
3106 is an average luminous reflectance in a bright place. Strictly speaking, the interface reflectance between the electromagnetic wave shield layer and the adjacent layer formed on the surface of the electromagnetic wave shield according to the present invention is reflection caused by the difference between the optical admittance of the adjacent layer and the optical admittance of the electromagnetic wave shield material. However, the optical admittance of a multilayer film such as an electromagnetic wave shield cannot be measured because it is calculated from the values of the optical constants of each layer. Therefore, the interface reflectance should be measured as follows. First, the reflectance R ₀ of the adjacent layer alone is measured with the back surface thereof painted black. Next, the adjacent layer is formed on the surface of the electromagnetic shielding material,
Similarly, the back surface is painted black and its reflectance R ₁ is measured. R
_1- R ₀ is defined as the above interface reflectance in the present invention.

The material of the silver-based transparent conductor thin film layer was composed of 80% by weight or more of silver and one or more elements selected from gold, copper, palladium, platinum, manganese, and cadmium. Things are used. Among the metallic materials, silver has the highest electric conductivity, small light absorption, and excellent optical transparency. However,
It easily deteriorates to moisture, sulfur and chlorine in the air. Therefore, from the viewpoint of electrical conductivity, optical transparency, and deterioration resistance,
A material in which 90 to 99% by weight of silver and 1 to 10% by weight of the above metal are solid-dissolved is preferable. A solid solution of 1 to 10% by weight of gold in silver is particularly preferable from the viewpoint of preventing deterioration of silver. If 10% by weight or more of gold is mixed, it will be colored,
The transparency is likely to be impaired, and the electrical conductivity is greatly reduced.
If the amount of gold mixed is less than 1% by weight, silver is likely to deteriorate.

As a material for the transparent thin film layer, any material having optical transparency can be used. The refractive index of the thin film layer may be selected so that desired optical characteristics can be easily achieved in optical design, and the material and refractive index of each layer may be different. A single material or a material obtained by sintering a plurality of materials may be used. It is more preferable if the material has a migration-preventing effect on the silver-based transparent conductor thin film layer and a water and oxygen barrier effect.

Suitable materials include indium oxide, tin oxide, titanium dioxide, cerium oxide, zirconium oxide,
Zinc oxide, tantalum oxide, niobium pentoxide, silicon dioxide,
Silicon nitride, aluminum oxide, magnesium fluoride, magnesium oxide, silicon dioxide, aluminum oxide,
Examples include one or more compounds selected from the group consisting of magnesium fluoride and magnesium oxide. A material containing indium oxide as a main component and containing a small amount of titanium dioxide, tin oxide, or cerium oxide has an effect of preventing deterioration of the metal thin film layer and has electrical conductivity, so that it is electrically connected to the metal thin film layer. It is preferable because it is easy to establish continuity. In forming these transparent thin film layers, it is preferable to employ a sputtering method from the viewpoint of film thickness controllability and uniformity.

The selective reflection type circularly polarizing plate 3 can be used without particular limitation as long as it is a polarizer exhibiting circular dichroism in a necessary wavelength range. For example, a large number of films having different optical anisotropies may be laminated to form this polarizer, but such a polarizer can be formed more easily by using a cholesteric liquid crystal layer. As the cholesteric liquid crystal layer,
Various compounds having cholesteric liquid crystallinity can be used without particular limitation. For example, the cholesteric liquid crystal layer is
It is formed of a liquid crystal polymer having various skeletons of a main chain type, a side chain type, or a composite type thereof showing cholesteric liquid crystal alignment.

Examples of the main chain type liquid crystal polymer include condensation type polymers having a structure in which mesogenic groups such as aromatic units are bonded, such as polyester type, polyamide type, polycarbonate type and polyester imide type polymers. To be Examples of the aromatic unit that becomes the mesogen group include phenyl-based, biphenyl-based, and naphthalene-based aromatic units, and these aromatic units have a substituent such as a cyano group, an alkyl group, an alkoxy group, or a halogen group. May be.

Examples of the side chain type liquid crystal polymer include those having a polyacrylate-based, polymethacrylate-based, polysiloxane-based or polymalonate-based main chain as a skeleton and having a mesogenic group composed of a cyclic unit or the like in the side chain.
Examples of the cyclic unit to be a mesogen group include biphenyl-based, phenylbenzoate-based, phenylcyclohexane-based, azoxybenzene-based, azomethine-based, azobenzene-based, phenylpyrimidine-based, diphenylacetylene-based, diphenylbenzoate-based, bicyclohexane-based, Examples thereof include cyclohexylbenzene type and terphenyl type. The ends of these cyclic units may have a substituent such as a cyano group, an alkyl group, an alkoxy group, or a halogen group.

Further, the mesogenic group of any of the above liquid crystal polymers may be bonded via a spacer portion which imparts flexibility. As the spacer part, a polymethylene chain,
Examples include polyoxymethylene chains. The number of repeating structural units forming the spacer portion is appropriately determined depending on the chemical structure of the mesogen portion, but the repeating unit of the polymethylene chain is 0 to 20, preferably 2 to 12, and the repeating unit of the polyoxymethylene chain is 0. -10, preferably 1
It is 3. The cholesteric liquid crystal polymer can be prepared by incorporating a low molecular weight chiral agent into the nematic liquid crystal polymer or introducing a chiral component into the polymer component.

The molecular weight of the liquid crystal polymer is not particularly limited, but it is preferably about 2,000 to 100,000 based on the weight average molecular weight. If the weight average molecular weight of the liquid crystal polymer is too large, the liquid crystal polymer tends to be difficult to form a uniform alignment state due to poor alignment properties as a liquid crystal, especially monodomain formation through a rubbing alignment film. Therefore, the weight average molecular weight of the liquid crystal polymer is more preferably 50,000 or less. Further, if the weight average molecular weight of the liquid crystal polymer is too small, the film-forming property as a non-fluid layer tends to be poor. Therefore, the weight average molecular weight of the liquid crystal polymer is more preferably 2.5 thousand or more.

The glass transition temperature of the liquid crystal polymer is appropriately determined depending on the purpose of use, but it is usually about 50 to 150 ° C. from the viewpoint of heat resistance of the substrate. The cholesteric liquid crystal layer is formed by applying a solution of a cholesteric liquid crystal polymer and drying it, or by polymerizing a polymerizable cholesteric liquid crystal monomer with heat or light. In the cholesteric liquid crystal layer, the chiral component exhibiting cholesteric properties is appropriately prepared according to the desired selective reflection band in the preparation stage of the cholesteric liquid crystal polymer or the polymerization stage of the cholesteric liquid crystal monomer. The thickness of the cholesteric liquid crystal layer is preferably 1 to 20 μm, and 2
10 μm is more desirable.

In forming the cholesteric liquid crystal layer, an alignment film is provided to align the cholesteric liquid crystal. As the alignment film, various conventionally known ones can be used, for example, a film formed by a method of rubbing a thin film made of polyimide or polyvinyl alcohol on a transparent substrate, a transparent film. Various films capable of aligning cholesteric liquid crystals, such as a stretched film obtained by stretching, a polymer having a cinnamate skeleton or an azobenzene skeleton, or a polyimide irradiated with polarized ultraviolet light can be used.

As described above, when the cholesteric liquid crystal is used, the selective reflection wavelength region in which circular dichroism is exhibited can be designed to some extent. For example, if cholesteric liquid crystal layers having different selective reflection wavelength regions are laminated in multiple layers,
A selective reflection type circularly polarizing plate which exhibits circular dichroism in the entire visible region of 780 nm can be produced.

External light reflection on the electromagnetic wave shield material 2 is reduced regardless of the selective reflection type circularly polarizing plate 3, as is clear from the description of FIG. Therefore, if the selective reflection wavelength range of the selective reflection type circularly polarizing plate 3 is basically only at the peak position of the emission spectrum of the display device 4, the effect of the present invention can be sufficiently exhibited. That is, it is preferable that the wavelength region having no emission peak does not have selective reflectivity.
This is because, of the external light reflected inside the display device, the reflected light that deviates from the selective reflection wavelength range of the selective reflection type circularly polarizing plate 3 is reduced by the same principle as the reflected light at the electromagnetic wave shield member 2, The incoming light can be further reduced. In this case, it can be easily realized by forming a cholesteric liquid crystal layer that exhibits selective reflection in the wavelength regions of the emission spectrum peaks of red, green, and blue in an overlapping manner. Further, these cholesteric liquid crystal layers may be formed by patterning for each pixel of the display device. In this case, the green area with high visibility is about 1 /
Since it can be reduced to 3, external light reflection can be further reduced.

As described above, in the present invention, it is essential that the selective reflection type circularly polarizing plate 3 exhibiting circular dichroism is provided in the emission wavelength range of the display device 4, and the wavelength range other than that is required. With respect to the above, it may be appropriately designed according to the purpose and is not particularly limited.

The electromagnetic wave shield filter for a display device of the present invention can be preferably used for any application as long as it is a display device which is required to have an electromagnetic wave shielding property. In particular, strong electromagnetic waves are radiated. It can be suitably used for PDPs. That is, the present invention can provide a PDP filter including the electromagnetic wave shield filter having the above configuration. In addition to the functions required for a normal display device, the PDP is further required to have a near infrared ray cut property and a Ne light emission cut property.

When the electromagnetic wave shielding material 2 is of a multi-layer type including a silver-based transparent conductor thin film layer and a transparent thin film layer, the electromagnetic wave shielding property and the near infrared ray cutting property can be satisfied at the same time. On the other hand, when a conductive mesh is used, or when the effect is insufficient with a silver-based transparent conductor thin film, the wavelengths of 850 to 1 are placed at any position between the absorptive circularly polarizing plate 1 and the display device 4. A layer that cuts near infrared rays of 1,000 nm may be appropriately inserted. The near infrared ray cut layer may be one using a phthalocyanine-based absorption material,
Two cholesteric liquid crystal layers that exhibit circular dichroism in the near-infrared wavelength range are attached together with a 1/2 wavelength phase difference plate, or cholesteric liquid crystal layers that are perpendicular to each other in the shake direction are also attached together. Used.

If the selective reflection type circularly polarizing plate 3 has no selective reflection property within the wavelength range of 580 to 590 nm, that is, if it does not exhibit circular dichroism in the Ne emission wavelength range, From the description of FIG. 2, about half of the emitted light in the wavelength range is absorbed by the absorption-type linear circularly polarizing plate 11, so that the Ne emission cut-off property can be improved about twice. Ne emission is usually around 585 nm, and its bandwidth is about 10 nm. However, the above-mentioned cut property can be realized by appropriately selecting the selective reflection wavelength region of the cholesteric liquid crystal layer and combining them. By doing so, the light transmittance of the orange emission light due to the Ne emission can be halved, and the color purity of the red emission can be improved.

In the present invention, the PDP filter having such a structure is attached to a separately prepared transparent molded body (the filter is formed and / or bonded), and P
A PDP display device can be obtained by producing a full-screen filter for DP and mounting it on the front surface of the PDP via an air layer. As another mode, the PDP filter having the above configuration is directly attached to the front display glass portion of the PDP main body via a transparent adhesive or a transparent adhesive, so that the characteristics of the present invention can be further utilized. It may be a device. In this case, an effect of preventing scattering when the front display glass portion is damaged can be obtained at the same time. At this time, in order to compensate for the insufficient strength of the front surface glass portion, an impact relaxation layer may be added and bonded.

[0057]

EXAMPLES Next, the present invention will be specifically described with reference to examples, but the present invention is not limited to the following examples. Further, as described above, the circularly polarized light is also expressed including elliptically polarized light that is close to perfect circularly polarized light. Furthermore, the evaluation items and evaluation methods in the following Examples and Comparative Examples are
It is as follows.

<Surface Resistance Value> Regarding the electromagnetic wave shielding material, the surface resistance value was measured by the four-point probe method using "Lorester SP" manufactured by Mitsubishi Petrochemical Co., Ltd.

<Average Luminous Reflectivity> Using an instantaneous multi-photometric system "MCPD3000" manufactured by Otsuka Electronics Co., Ltd., the reflection spectrum is 10 nm in the wavelength range of 380 to 780 nm.
It was measured every other time. Based on that data, JIS R310
6, the average luminous reflectance was calculated.

<Interfacial reflectance> One side of the acrylic pressure-sensitive adhesive was painted black and the average luminous reflectance was measured. Next, attach the acrylic adhesive to the surface of the electromagnetic wave shielding material,
The average luminous reflectance was measured with the back surface of the electromagnetic wave shield material being painted black. The increase in the average luminous reflectance after bonding the electromagnetic wave shield material was defined as the interface reflectance.

<Reflectance of Filter> In the PDP display device, the entire PDP display was black display, and the average luminous reflectance at that time was measured.

<Emission intensity ratio> Using the instantaneous multi-photometry system "MCPD3000" manufactured by Otsuka Electronics Co., Ltd., the PDP display is displayed in white and the peak intensity of green emission when no filter is attached is measured. Was set to 1. Under the same conditions, the strength when the filter was installed was measured, and the ratio with that without the filter was obtained. This ratio roughly corresponds to the transmittance of the filter.

<Near-infrared cut-off rate> The instantaneous multi-photometry system "MCPD3000" manufactured by Otsuka Electronics Co., Ltd. was used to measure the transmittance at a wavelength of 900 nm, and the measured value was 100%.
Was subtracted from the above to obtain the near infrared ray cut rate.

Example 1 <Production of Absorption Circularly Polarizing Plate> A birefringent film obtained by stretching a polyvinyl alcohol film having a thickness of 75 μm in a 5% by weight oxalic acid aqueous solution (30 ° C.) by 300%, and a thickness. 5
35% of 0μm polycarbonate film at 160 ℃
The birefringent films obtained by stretching were laminated via a transparent acrylic pressure-sensitive adhesive so that their optical axes were orthogonal to each other to obtain a quarter-wave retardation plate. Furthermore, a polarizing film (“NPF manufactured by Nitto Denko Corporation” is used so that the optical axis of the polyvinyl alcohol film crosses the transmission axis at an angle of 45 degrees through a transparent acrylic adhesive. -G1225DU "), and an absorption type circularly polarizing plate that transmits right circularly polarized light was produced.

<Production of electromagnetic wave shield material> Thickness 50 μm
Prepare 2 sheets of transparent acrylic adhesive and wire diameter 50μ
m, pitch 190 μm, aperture ratio 63%, surface resistance value 0.
A fiber mesh of 1Ω / □ was sandwiched between the above acrylic adhesives and bonded, and defoaming treatment was carried out in an autoclave to prepare an electromagnetic wave shielding material made of a conductive mesh.

<Preparation of Selective Reflective Circularly Polarizing Plate> (1) A polyvinyl alcohol layer having a thickness of 0.1 μm was provided on a cellulose triacetate film having a thickness of 50 μm and showing no optical anisotropy, and a rayon cloth was used. An alignment film is formed by rubbing treatment, a 20 wt% tetrahydrofuran solution of an acrylic thermotropic cholesteric liquid crystal polymer is applied on the alignment film with a wire bar and dried, and then heated at 150 ± 2 ° C for 5 minutes. After the alignment treatment, it is allowed to cool at room temperature to form a cholesteric liquid crystal polymer layer having a thickness of 1 μm, and the wavelength range showing circular dichroism is (A).
350-450 nm, (B) 450-550 nm,
(C) 600 to 700 nm, (D) 750 to 850 nm
Then, four types of cholesteric liquid crystal polymer layers that reflect left-handed circularly polarized light were obtained. (2) Next, the cholesteric liquid crystal polymer layers of (A) and (B) described above are adhered to each other at their liquid crystal surfaces to form 150
After heat and pressure treatment at ± 2 ° C. for 2 minutes, the cellulose triacetate film on the (B) side is peeled off, and the cholesteric liquid crystal polymer layer of (C) is adhered to the exposed surface of the liquid crystal polymer layer. Then, after heat-pressing treatment at 150 ± 2 ° C. for 2 minutes, the cholesteric liquid crystal polymer layer of (D) is also heat-pressing treatment according to the above, and the helical pitch changes in the thickness direction to obtain circular dichroism. Wavelength range shown is 400-8
A 00 nm selective reflection type circularly polarizing plate was produced.

<Production of Electromagnetic Wave Shield Filter> The surface of the retardation plate of the above-mentioned absorption type circularly polarizing plate and the electromagnetic wave shield material composed of the above conductive mesh are bonded together, and the opposite surface of this electromagnetic wave shield material and the above The surfaces of the cholesteric liquid crystal layer of the selective reflection type circularly polarizing plate were pasted together. After that, the reflectance is 1.0% on the surface of the linear polarizing plate of the absorption type circular polarizing plate.
A commercially available anti-reflection film (trade name “Rialck 2200” manufactured by NOF CORPORATION) was attached via a transparent acrylic pressure-sensitive adhesive to prepare an electromagnetic wave shield filter.

<Production of PDP Display Device> The above electromagnetic wave shield filter is used as a PDP filter, and this is 10 cm.
Cut out to a size of 10 cm, and the side of the selective reflection type circularly polarizing plate is a PDP display device (type name "PDP manufactured by Pioneer".
-502HP "), the front plate filter was removed, and it was directly attached to the front glass portion of the main body display panel via a transparent acrylic pressure-sensitive adhesive to manufacture a PDP display device.

Comparative Example 1 An electromagnetic wave shield filter was produced in the same manner as in Example 1 except that the selective reflection type circularly polarizing plate was not used, and a PDP display device was produced using this.

Comparative Example 2 Without using both the absorption type circularly polarizing plate and the selective reflection type circularly polarizing plate,
An electromagnetic wave shield filter was produced in the same manner as in Example 1 except that an antireflection film was attached to one surface of the electromagnetic wave shield material made of a conductive mesh, and a PDP display device was produced using this. .

COMPARATIVE EXAMPLE 3 In Example 1, the retardation plate was set so that the optical axis was 13 relative to the transmission axis.
A polarizing film was laminated so as to intersect with each other at an angle of 5 degrees to prepare an absorption-type circularly polarizing plate that transmits left circularly polarized light. An electromagnetic wave shield filter was produced in the same manner as in Example 1 except that this was used, and a PDP display device was produced using this.

Comparative Example 4 A wire diameter of 15 μm, a pitch of 170 μm, an aperture ratio of 87% prepared by the photolithography method in Example 1 were used.
An electromagnetic wave shielding material made of a conductive mesh was produced using a blackened mesh having a surface resistance value of 0.8Ω / □. Except for using this, in the same manner as in Example 1,
I made an electromagnetic wave shield filter, and using this,
A PDP display device was produced.

Comparative Example 5 Without using both the absorption type circularly polarizing plate and the selective reflection type circularly polarizing plate,
An electromagnetic wave shield filter was produced in the same manner as in Comparative Example 4 except that an antireflection film was attached to one surface of the electromagnetic wave shield material made of a conductive mesh, and a PDP display device was produced using this. .

PDs of Example 1 and Comparative Examples 1 to 5 above
Regarding the P display device, the surface resistance value of the electromagnetic wave shielding material,
The emission intensity ratio and the reflectance of the filter were examined. These results are shown in Table 1 together with the evaluation of the low cost of the mesh filter. The low cost property was evaluated as ◯ when the blackening treatment and the photolithography process were not required and the cost was low, and as x when the blackening treatment and the photolithography process were required and the cost was high.

[0075]

As is clear from the results shown in Table 1 above, in Example 1 of the present invention, the emission intensity ratio was low even though the conductive mesh which was inexpensive and had a large wire diameter was used as the electromagnetic wave shielding material. The reflectance was high and the reflectance of the filter at the time of black display was suppressed to be low, so that a PDP display device with a tight image and a high bright room contrast could be obtained. Moreover, the electromagnetic wave shielding property was such that the electromagnetic wave generated from the PDP could be sufficiently shielded from the surface resistance value of 0.1 Ω / □.

On the other hand, in Comparative Example 1 in which the selective reflection type circularly polarizing plate was not used, the reflectance was low, but
The emission intensity ratio decreased to 0.30, and the device became a dark PDP display device. In Comparative Example 2 in which only the conductive mesh is mounted,
Although the emission intensity ratio was high and bright, the reflectance was 15.9% and the bright room contrast was extremely low. In Comparative Example 3 in which the circularly polarized light absorbed by the absorptive circularly polarizing plate and the circularly polarized light in the opposite direction are reflected, almost all the emitted light from the PDP is absorbed by the absorptive circularly polarizing plate, and the emission intensity ratio is Is 0.0
It decreased to 1%, and the PDP display became almost invisible.

Further, in Comparative Example 4 in which a fine one was prepared by making full use of photolithography for the conductive mesh, the emission intensity ratio was increased due to the higher aperture ratio, but the surface resistance value was 0. It was 0.8 Ω / □, the electromagnetic wave shielding property was poor, and the cost was very high, and no superiority was observed as compared with Example 1. Further, in Comparative Example 5 in which only the fine conductive mesh was mounted, the reflection of the mesh became a concern when the external light became strong, and the PDP itself was bright, but the bright room contrast was low.

Example 2 As an electromagnetic wave shield material, a multilayer film type including a silver-based transparent conductor thin film layer was prepared as follows. That is, a 75 μm thick norbornene-based resin film (J
Electromagnetic waves are formed on one surface of SR (trade name "Arton" manufactured by SR Inc.) by a DC magnetron sputtering method by repeatedly forming a high refractive index transparent thin film, a silver-based transparent conductor thin film, and a high refractive index transparent thin film in this order. A shield material was produced. As a target material for forming a high refractive index transparent thin film, In ₂
O ₃ -12.6 wt% TiO ₂ (hereinafter referred to as ITO)
Ag-5 wt% Au (hereinafter, simply referred to as Ag) is used as a target material for forming a silver-based transparent conductive thin film.
It was used. The film thickness was controlled using a calibration curve of the film formation rate obtained from the measurement of the film thickness by a film surface roughness meter (“DEKTAK3”) attached to the thick film.

The electromagnetic wave shielding material produced in this way is
It had the following structure. However, the film thickness (nm) is shown in parentheses. Arton film / ITO (40) / Ag (20) / I
TO (40) Example 1 except that this electromagnetic wave shielding material was used and the multilayer film side was bonded via a transparent acrylic pressure-sensitive adhesive so that the multilayer film side was the retardation plate side of the absorption type circularly polarizing plate.
An electromagnetic wave shield filter was produced in the same manner as in 1. and a PDP display device was produced using the same.

Example 3 The composition of the electromagnetic wave shielding material was as follows: Arton film / ITO (35) / Ag (13) / I
TO (70) / Ag (13) / ITO (70) / Ag
An electromagnetic wave shield filter was produced in the same manner as in Example 2 except that (13) / ITO (35) was used. However, the film thickness (n
m) is shown. In addition, a PDP display device was manufactured using this electromagnetic wave shield filter.

Comparative Example 6 An electromagnetic wave shield filter was produced in the same manner as in Example 2 except that the selective reflection type circularly polarizing plate was not used, and a PDP display device was produced using this.

Comparative Example 7 Absorption type circularly polarizing plate and selective reflection type circularly polarizing plate were not used,
An electromagnetic wave shield filter was prepared in the same manner as in Example 2 except that an antireflection film was attached to one side of a multilayer film type electromagnetic wave shield material including a silver-based transparent conductor thin film layer. A PDP display device was manufactured using the above.

Comparative Example 8 As the selective reflection type circularly polarizing plate, a cholesteric liquid crystal having a deflection direction opposite to that of Example 2 was used, and the selective reflection type circularly polarizing plate which reflects right circularly polarized light and transmits left circularly polarized light. An electromagnetic wave shield filter was produced in the same manner as in Example 2 except that was used, and a PDP display device was produced using this.

Comparative Example 9 The composition of the electromagnetic wave shielding material was as follows: Arton film / ITO (44) / Ag (6.5) /
An electromagnetic wave shield filter was produced in the same manner as in Example 2 except that ITO (44) was used. However, the film thickness (n
m) is shown. In addition, a PDP display device was manufactured using this electromagnetic wave shield filter. The filter is designed so that the optical admittance of the acrylic pressure-sensitive adhesive and the optical admittance of the electromagnetic wave shielding material are matched so as to minimize the interface reflectance, and the thickness of the Ag layer is selected to be 6.5 nm. It is

For the PDP display devices of Examples 2 and 3 and Comparative Examples 6 to 9 described above, the interface reflectance between the electromagnetic wave shield material and the acrylic pressure-sensitive adhesive which is the adjacent layer formed on the surface of the electromagnetic wave shield material was examined. The results were as shown in Table 2 below.

[0087]

Next, with respect to the PDP display devices of Examples 2 and 3 and Comparative Examples 6 to 9 described above, the surface resistance value of the electromagnetic wave shielding material, the reflectance of the filter, the emission intensity ratio and the near infrared ray cut rate were examined. The results were as shown in Table 3 below.

[0089]

As is clear from the results shown in Tables 2 and 3, in Example 2, a relatively low surface resistance was obtained because the film thickness was increased to 20 nm with a simple Ag single layer structure. However, since the optical design is not such that the optical admittance of the electromagnetic wave shielding material and the acrylic pressure-sensitive adhesive which is the adjacent layer are matched, the interface reflectance was as large as 22.4%. However, with the configuration of the present invention, the reflectance of the filter was reduced to 1.7%, and a high emission intensity ratio could be achieved. Similarly, in Example 3,
By making the electromagnetic wave shield material a further multilayer structure,
It was possible to achieve both lower surface resistance and excellent near-infrared ray cutting property.

On the other hand, Comparative Examples 6 to 8 were similar to the results shown in Table 1 and were not suitable as the electromagnetic wave shield filter for the display device. In Comparative Example 9 in which the optical admittances of the electromagnetic wave shield material and the acrylic pressure-sensitive adhesive are matched, a simple Ag is used.
With a one-layer structure, the film thickness must be as thin as 6.5 nm. In this case, the interface reflectance can be suppressed to 0.2%, and the two types of circularly polarizing plates of the present invention are not used. A low reflectance and a high emission intensity ratio were achieved, but the surface resistance was 30.3.
It suddenly increased to Ω / □ and the electromagnetic wave shielding property was extremely deteriorated.

Example 4 An electromagnetic wave shield filter was produced in the same manner as in Example 1 except that the following near infrared ray cut film was inserted between the absorptive circularly polarizing plate and the electromagnetic wave shield material made of a conductive mesh. Further, using this, a PDP display device was manufactured.

<Near-Infrared Cut Film> (1) A polyvinyl alcohol layer having a thickness of 0.1 μm is provided on a cellulose triacetate film having a thickness of 50 μm which does not show optical anisotropy and rubbed with a rayon cloth. An alignment film is formed by applying a 20 wt% tetrahydrofuran solution of an acrylic thermotropic cholesteric liquid crystal polymer on the alignment film with a wire bar and drying, and then heat alignment treatment at 150 ± 2 ° C. for 5 minutes. In the method of cooling at room temperature to form a cholesteric liquid crystal polymer layer having a thickness of 1 μm, the wavelength range showing circular dichroism is (A) 800 to 900 nm, (B) 900 to 1,000.
nm, (C) 1,000 to 1,100 nm to obtain three types of cholesteric liquid crystal polymer layers that reflect left-handed circularly polarized light. (2) The cholesteric liquid crystal polymer layers of (A) and (B) are brought into close contact with each other at their liquid crystal surfaces, and the cholesteric liquid crystal polymer layer is heated at 150 ± 2 ° C. for 2 hours.
After heat and pressure treatment for minutes, the cellulose triacetate film on the (B) side is peeled off, and the cholesteric liquid crystal polymer layer of the above (C) is adhered to the exposed surface of the liquid crystal polymer layer, and the liquid crystal surfaces are adhered to each other by 150 ± The mixture was heated and pressed at 2 ° C. for 2 minutes to produce a selective reflection type circularly polarizing plate having a wavelength range of 800 to 1,100 nm that exhibits circular dichroism by changing the screw pitch in the thickness direction. (3) In the same manner as above, the screw pitch is reverse swing,
A selective reflection type circularly polarizing plate that reflects right circularly polarized light was produced. These two selective reflection type circularly polarizing plates are pasted together with a transparent acrylic pressure-sensitive adhesive, and the wavelength is 800 to 1,100 nm.
A near-infrared cut film that totally reflects the near-infrared rays was produced. FIG. 3 shows the transmission spectrum of this near-infrared cut film.

In Example 1, since a conductive mesh was used as the electromagnetic wave shielding material, the near infrared ray cut property, which is a function required as a PDP filter, was not obtained. However, in Example 4 described above, by inserting the near-infrared ray cut film, the near-infrared ray cutability is easily imparted while maintaining functions such as electromagnetic wave shielding properties, low visible light reflectance, and high visible light transmittance. We were able to.

Example 5 An electromagnetic wave shield filter was produced in the same manner as in Example 4 except that the selective reflection type circularly polarizing plate produced by the following method was used as the selective reflection type circularly polarizing plate. A PDP display device was manufactured using the above.

<Preparation of Selective Reflective Circularly Polarizing Plate> (1) Rayon cloth with a polyvinyl alcohol layer having a thickness of 0.1 μm provided on a cellulose triacetate film having a thickness of 50 μm which does not exhibit optical anisotropy. To form an alignment film, and a 20 wt% tetrahydrofuran solution of acrylic thermotropic cholesteric liquid crystal polymer is applied on the alignment film with a wire bar and dried, and then at 150 ± 2 ° C. for 5 minutes. After the heating alignment treatment, the system is left to cool at room temperature to form a cholesteric liquid crystal polymer layer having a thickness of 1 μm, and the wavelength range showing circular dichroism is (A).
400-500 nm, (B) 460-560 nm,
(C) Three types of cholesteric liquid crystal polymer layers that reflect left-handed circularly polarized light at 600 to 700 nm were obtained. (2) Next, the films of (A), (B), and (C) described above were bonded together via an acrylic pressure-sensitive adhesive to produce a selective reflection type circularly polarizing plate. FIG. 4 shows the transmission spectrum (curve-a) of the selective reflection type circularly polarizing plate thus produced and the emission spectrum (curve-b) of the PDP display device produced in Example 5 during white light emission. It is also shown.

As shown in FIG. 4, the selective reflection type circularly polarizing plate used in this Example 5 is designed so as not to exhibit selective reflection in the Ne emission wavelength region appearing in the wavelength of 580 to 590 nm. Here, the emission color of Ne is orange emission, which reduces the color purity of red of the PDP display device.
It is desirable to cut. From the principle of the present invention, the light in the above wavelength range is not affected by the selective reflection type circularly polarizing plate, and enters the absorption type circularly polarizing plate as natural light, and at least 50% thereof is absorbed by the circularly polarizing plate. In other words, the necessary emission color works by the action of the selective reflection type circularly polarizing plate of the present invention so as not to be absorbed by the absorption type circularly polarizing plate, and unnecessary Ne light can be halved. As a result, the peak intensity of Ne light with respect to other emission peaks is reduced, and the color reproducibility and color purity of PDP can be improved. Of course, the electromagnetic wave shielding property and other optical properties were not affected at all, and the composition was suitable for use.

[0098]

As described above, according to the present invention, in the conventional circular polarization filter method, which has a problem that the reflection of external light can be reduced but the emission intensity thereof is also halved, the decrease in emission intensity accompanying it is minimized. It can be limited. Moreover,
Only by providing a selective reflection type circularly polarizing plate, it is possible to manufacture a display device that has excellent electromagnetic wave shielding properties, does not impair the emission brightness of the display device as much as possible, has little external light reflection, has excellent visibility, and has high bright room contrast. The electromagnetic wave shielding filter can be provided as a single composite film. Further, by using this filter, it is possible to provide a PDP display device having excellent visibility without becoming a noise source for external peripheral devices.

[Brief description of drawings]

FIG. 1 is a schematic view showing a basic configuration of an electromagnetic wave shield filter for a display device of the present invention.

FIG. 2 is an explanatory view of the operation of the electromagnetic wave shield filter.

FIG. 3 is a diagram showing a transmission spectrum of a near-infrared cut film used in Example 4.

FIG. 4 is a diagram showing a transmission spectrum of the selective reflection type circularly polarizing plate used in Example 5 and an emission spectrum of the PDP display device produced in Example 5 during white light emission.

[Explanation of symbols]

A Electromagnetic wave shield filter for display device 1 Absorption type circularly polarizing plate 11 Absorption type linear polarizing plate 12 1/4 wave retarder 2 Electromagnetic wave shield material 3 Selective reflection type circularly polarizing plate 4 display device

Front page continuation (51) Int.Cl. ⁷ identification code FI theme code (reference) H04N 5/72 H05K 9/00 V 5G435 H05K 9/00 G02B 1/10 Z (72) Inventor Shusaku Nakano Ibaraki City, Osaka Prefecture Shimohozumi 1-2, Nitto Denko Co., Ltd. F-term (reference) 2H048 AA06 AA16 AA18 2H049 BA02 BA03 BA05 BA07 BB67 BC22 2K009 CC03 CC14 EE03 5C058 AA11 DA08 5E321 AA04 BB21 BB41 CC16 GG05 GH16BB06AFF

Claims (9)

[Claims] 1. A circularly polarized light that is in the same direction as the circularly polarized light absorbed by the absorption circularly polarizing plate, the electromagnetic wave shielding material, and the absorption circularly polarizing plate is reflected in order from the viewer side of the display device, An electromagnetic wave shield filter for a display device, comprising a selective reflection type circularly polarizing plate that transmits circularly polarized light in the opposite direction. 2. The electromagnetic wave shield filter for a display device according to claim 1, wherein the selective reflection type circularly polarizing plate comprises a cholesteric liquid crystal layer exhibiting circular dichroism. 3. The electromagnetic wave shield filter for a display device according to claim 1, wherein the electromagnetic wave shield material is made of a conductive mesh and has a line width of 20 μm or more and an aperture ratio of 85% or less. 4. The electromagnetic wave shield material includes one or more silver-based transparent conductor thin film layers, and has an interface reflectance of 0.5 to 30% between the electromagnetic wave shield material and an adjacent layer formed on the surface thereof. An electromagnetic wave shield filter for a display device according to claim 1 or 2. 5. A filter for a plasma display panel, comprising the electromagnetic wave shield filter according to any one of claims 1 to 4. 6. The filter for a plasma display panel according to claim 5, wherein a layer for cutting near infrared rays having a wavelength of 850 to 1,000 nm is inserted between the absorption type circularly polarizing plate and the display device. 7. The selective reflection type circularly polarizing plate has a wavelength of 580-5.
The plasma display panel filter according to claim 5, which does not have selective reflectivity in a range of 90 nm. 8. A front surface of the plasma display panel,
A plasma display panel display device, comprising: a transparent molded body installed via an air layer, and a plasma display panel front filter having the plasma display panel filter according to any one of claims 5 to 7 attached thereto. . 9. The filter for a plasma display panel according to claim 5, which is directly bonded to the front display glass portion of the plasma display panel body via a transparent adhesive or a transparent adhesive. Plasma display panel display device characterized by: