JP2007094301A - Front filter for pdp - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a front filter for PDP which suppresses whitening of a black display part of a PDP, which accompanies spark discharge, to give high contrast to an image. <P>SOLUTION: The front filter for PDP has at least a substantially achromatic light absorbing filter and has a total transmittance of 15 to 35%. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a PDP front filter used by being arranged in front of a PDP (Plasma Display Panel), and more particularly to a PDP front filter having a light absorption filter that enables beautiful black display and high contrast of an image. .

  In recent years, a plasma display panel (PDP) has attracted attention as a flat screen image display device with a large screen. The PDP excites the Xe (xenon) gas and Ne (neon) gas molecules enclosed by the discharge between the electrodes, and generates ultraviolet rays as excitation luminescence when the excited state molecules return to the lower level, Light in the visible region is generated by irradiating phosphors of R (red), G (green), and B (blue) with the ultraviolet rays.

  In the PDP, even in a so-called black state where the light emission intensity of the panel is the lowest, a weak discharge called a seed discharge (priming) is always performed. This is because when black display is performed, if the electrode voltage is set to 0 and the discharge is completely stopped, it takes time to perform color display again. However, due to this kind of fire discharge, the brightness of the black display portion becomes high, so that the black display portion looks whitish and cannot be felt as a complete black display, and as a result, the contrast (monochrome density difference) of the image is insufficient. The problem of being felt is occurring.

  Conventionally, for example, as disclosed in Patent Document 1, in addition to the function of shielding near infrared rays and electromagnetic waves generated from a PDP, it is visible for the purpose of correcting the color tone of an image and absorbing the emission spectrum of Ne atoms. There has been proposed a colored filter in which a near-infrared absorption filter to which a pigment that absorbs a partial band of a light beam is added and an electromagnetic wave shielding sheet are integrated. However, the coloring filter is intended to adjust the color tone of the PDP and does not suppress an increase in the brightness of the black display portion of the PDP.

JP 11-116826 A

  The present invention provides a front filter for a PDP that is arranged and used on the front surface of a PDP, which suppresses whitening due to a seed discharge in a black display portion of the PDP and enables high contrast of an image. With the goal.

The front filter for PDP of the present invention has at least a substantially achromatic light absorption filter and has a total light transmittance of 15 to 35%.
According to the front filter for PDP according to the present invention, by adjusting the total light transmittance to 15 to 35% by the substantially achromatic light absorption filter, the screen output light intensity can be suppressed in the black display portion, and visually. It becomes less than the threshold value that can be recognized and does not feel whiteness due to the seed discharge, and can be recognized as complete black. On the other hand, although the screen output light intensity can be suppressed even in the white display portion, the white intensity is higher than the threshold that can be visually recognized, and the light intensity is stronger than the surroundings, so the white color appears relatively maintained. Therefore, visually, the density difference between black and white becomes large and the contrast is felt high.

  The front filter for PDP of the present invention has an electromagnetic wave shielding function, a near infrared absorption function, a neon light absorption function, a color tone adjustment function, an ultraviolet absorption function, an antireflection function, an antiglare function, an anti-scratch function, and It is preferable to have one or two or more types of antifouling functions.

  The present invention can provide a front filter for a PDP that can suppress whitening of an image due to seed discharge in a black display portion of the PDP and enables high contrast of the image.

The front filter for PDP of the present invention is characterized by containing at least a substantially achromatic light absorption filter and having a total light transmittance of 15 to 35%.
According to the front filter for PDP according to the present invention, by adjusting the total light transmittance to 15 to 35% by the substantially achromatic light absorption filter, the screen output light intensity can be suppressed in the black display portion, and visually. Since the brightness is less than the threshold that can be recognized, the whiteness due to the seed discharge is not felt, and it can be visually recognized as complete black. On the other hand, although the screen output light intensity can be suppressed even in the white display portion, the white intensity is higher than the threshold that can be visually recognized, and the light intensity is stronger than the surroundings, so the white color appears relatively maintained. Therefore, visually, the density difference between black and white becomes large and the contrast is felt high.

  When the total light transmittance exceeds the above range, when the front filter for PDP is installed and used in the PDP, the light intensity (luminance) is not less than the threshold for visual recognition at the black display portion, so the image is slightly white. Taste is felt (hereinafter sometimes referred to as “white”), and the recognizable range (dynamic range) of density and color is compressed in the low density part and the high density part, particularly in the low density part. Therefore, the contrast may be insufficient. Also, when the total light transmittance is less than the above range, the black display is sufficiently black, but for example, a dark color display such as dark brown or magenta that can be recognized without the front filter is black. Recognized (hereinafter sometimes referred to as “blackout”), the perceivable range (dynamic range) of density and color is also compressed in both the high and low density parts, particularly the high density part. Further, in the white display portion, the image may be slightly black and the contrast may be insufficient.

The contrast evaluation of the PDP provided with the PDP front filter of the present invention is performed by sensory evaluation (visual evaluation). Using a luminance meter, measure the luminance when displaying black (black luminance) and the luminance when displaying white (white luminance). The contrast calculated from these values, the chromaticity measured with a spectrocolorimeter, and human This is because the quality of the contrast and the color tone based on this sense do not always match.
The sensory evaluation of contrast is, for example, two colors consisting of image data of the highest density of achromatic color (perfect black) and the lowest density of achromatic color (perfect white), with grid lines (rectangular grids) alternately (white Place the filter on the front of the image data (Fig. 4) of the pattern that has been arranged (with all black next to it and all white next to black). The quality can be judged by whether or not the black and white border of the pattern is clearly visible.

The sensory evaluation of the blackout is, for example, achromatic gradation image data (FIG. 5) having 15 levels of density obtained by equally dividing the interval between complete black and complete white at 15 equal density intervals, and red, orange , Yellow, green, blue, indigo, azure, and achromatic colors are displayed in different shades of color in 5 levels and displayed in 40 different shades of image data (Fig. 6) in a predetermined PDP. In addition, the front filter for PDP obtained in the example or the comparative example can be installed on the front surface for evaluation. Here, the concentration is defined as an amount proportional to the common logarithm of the reciprocal of the light intensity. Also, it has a correlation with luminance on the screen.
In the evaluation of the blackout, the display of the image data displayed by the PDP is visually observed through the filter, and the black of the darkest part and the black of the next density in the display of the gradation color image data of the infinite color are displayed. Or “blackout” when the image data of 40 colors is not distinguishable from the seven chromatic colors having the highest density and the achromatic color having the highest density (completely black on the data). It can be determined that there is.

  The white sensory evaluation can be determined to be “white” when, for example, whitening in the display portion of the achromatic color gradation image data (FIG. 5) can be clearly distinguished.

〔Layer structure〕
The basic form of the PDP front filter of the present invention will be described below.
The front filter for PDP of the present invention only needs to have at least a substantially achromatic light absorption filter. In the present invention, since the range of the total light transmittance of the front filter for PDP is set to the above range using the substantially achromatic light absorption filter, the screen output light intensity can be suppressed in the black display portion, and It can be recognized as complete black by visual inspection without feeling whiteness due to electric discharge. The substantially achromatic light absorption filter has an electromagnetic shielding function, a near infrared absorption function, a neon light absorption function, a color tone adjustment function, an ultraviolet absorption function, an antireflection function, an antiglare function, an anti-scratch function, and an antifouling function. Any one or two or more functions may be provided. The layer structure of the PDP front filter may be a single layer or two or more layers. For example, a single-layer substantially achromatic light absorption filter may be used as the front filter for PDP, or a laminate of the transparent substrate 1 and the substantially achromatic light absorption filter 2 as shown in FIG. It may be used as a filter.

  In addition, the PDP filter of the present invention includes an electromagnetic wave shielding function, a near infrared absorption function, a neon light absorption function, a color tone adjustment function, an ultraviolet absorption function, an antireflection function, an antiglare function, an anti-scratch function, an anti-scratch function as necessary. One layer or two or more layers having one or two or more functions of the contamination function may be further laminated. For example, as shown in FIG. 2, an electromagnetic wave shielding filter 3 having a metal mesh region, an adhesive layer 4, and a substantially achromatic light absorption filter 2 are sequentially laminated on the transparent substrate 1, or as shown in FIG. The laminated body of the structure which laminated | stacked the electromagnetic wave shielding filter 3 which has a metal mesh area | region on the transparent base material 1, the adhesive bond layer 4, the substantially achromatic light absorption filter 2, the near-infrared absorption filter 5, and the antireflection filter 6 in order. Can be used as a front filter for PDP. In FIG. 3, the adhesive layer 4 may have a neon light absorption function, a color tone adjustment function, and / or an ultraviolet absorption function, and further, an antifouling layer is provided on the antireflection filter 6 below. May be provided with an antiglare layer and / or an anti-scratch layer.

  In addition, the above illustration does not limit the aspect of the front filter for PDP of this invention. Any device that has substantially the same structure as the technical idea described in the claims of the present invention and that exhibits the same effect can be included in the technical scope of the present invention. .

Hereinafter, the front filter for PDP of this invention is demonstrated in order for every layer.
[Substantially achromatic light absorption filter]
The substantially achromatic light absorption filter according to the present invention is a filter that absorbs light so as to maintain a substantially achromatic color in the entire visible spectrum band (380 to 780 nm). By being an achromatic color, the contrast can be improved without affecting the color of the image. The total light transmittance of the substantially achromatic light absorption filter is adjusted so that the total light transmittance (JIS K7105) of the front filter for PDP is 15 to 35% which is the range of the present invention.

The total light transmittance of the substantially achromatic light absorption filter single layer is selected in a range of 15 to 35% when the substantially achromatic light absorption filter is a single layer PDP front filter. In addition, when a substantially achromatic light absorption filter and other layers (electromagnetic wave shielding filter, antireflection filter, etc.) are laminated to form a front filter for PDP, the total light transmittance of other layers and the laminated structure Since it depends on the total light transmittance, it is generally not necessary to select one having a total light transmittance of about 35 to 65%.
The substantially achromatic color mentioned here includes a typical achromatic color as a matter of course, but it does not necessarily have to be an achromatic color with a strict definition in terms of chromaticity. Strictly speaking, even if it is in the category of chromatic colors, the present invention is effective if it is in a category in which the hue of the image is not visually perceived as being unnaturally shifted when viewed from the front of the image display device. Treated as a neutral color. For example, a slightly reddish black, a slightly bluish black, a slightly greenish black, a slightly purpleish black, and the like.

  As the substantially achromatic light absorption filter, a substantially achromatic light absorption filter forming composition containing substantially achromatic powder such as black powder in a transparent resin is formed into a single layer of substantially achromatic light absorption filter. A light absorption filter may be formed, or applied on a functional filter described later, and a single layer substantially achromatic light absorption filter may be formed through drying, curing treatment, etc., if necessary. Or the said composition may be apply | coated on a transparent base material, and a substantially achromatic light absorption filter of two or more layers may be formed through drying, a hardening process, etc. as needed. A substantially achromatic color commercial film (for example, black PET (polyethylene terephthalate)) may be used.

  As the black powder used in the substantially achromatic light absorption filter, for example, one or more kinds of light-shielding particles such as inorganic pigments such as carbon black and metal oxide, and organic pigments such as aniline black are used. be able to. Alternatively, a known achromatic color may be obtained by mixing known yellow, red and blue pigments. For example, yellow pigments such as yellow lead and isoindolinone yellow, red pigments such as petals and quinacridone red, and blue pigments such as cobalt blue, phthalocyanine blue, and diimmonium dyes are used.

  The transparent resin used for the substantially achromatic light absorption filter is appropriately selected from resins that do not substantially change the transmission spectrum of the front filter for PDP. For example, as a transparent resin suitable for film formation, a transparent resin usually used for a transparent substrate is preferably used. For example, polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, terephthalic acid-isophthalic acid- Polyester resins such as ethylene glycol copolymers, terephthalic acid-cyclohexanedimethanol-ethylene glycol copolymers, polyamide resins such as nylon 6, polyolefin resins such as polypropylene and polymethylpentene, and acrylic resins such as polymethyl methacrylate Examples thereof include resins, polystyrene, styrene resins such as styrene-acrylonitrile copolymer, cellulose resins such as triacetyl cellulose, imide resins, and polycarbonate resins. Moreover, as a transparent resin suitable for use on a transparent substrate or a functional filter described later to form a coating film, it is appropriately selected from those conventionally used as a known binder resin. For example, a resin such as a polyester resin, a polyurethane resin, an acrylic resin, an epoxy resin, or a vinyl chloride-vinyl acetate copolymer is used.

  Substantially achromatic light absorption filter is any of electromagnetic shielding function, near infrared absorption function, neon light absorption function, color tone adjustment function, ultraviolet absorption function, antireflection function, antiglare function, anti-scratch function, and antifouling function. Since it may also have one or two or more functions, the composition for forming a substantially achromatic light absorbing filter may have a near-infrared absorbing dye, neon light absorption as described later, as necessary. You may add additives, such as a pigment | dye, a color tone adjustment pigment | dye, a ultraviolet absorber, a filler, a plasticizer, an antifouling agent, and an antistatic agent.

  The method for forming the substantially achromatic light absorbing filter forming composition is not particularly limited, and when forming a single layer, a known film forming method such as a melt extrusion method, a casting method, or a calendar method may be used. It can be used as appropriate. Moreover, when apply | coating on a transparent base material, well-known coating methods, such as a roll coat, a gravure roll coat, a bar coat, and a comma coat, are used as a coating method. Drying and curing methods after the coating film is formed include dry solidification method by drying solvent (or dispersion medium) from solution (or emulsion), polymerization by energy such as heat, ultraviolet ray, electron beam, and crosslinking reaction. A curing method using a reaction such as crosslinking or polymerization between a functional group such as a hydroxyl group or an epoxy group in a resin and an isocyanate group in a curing agent can be applied.

  On the other hand, if the transparent base material that is a support for the coating film of the substantially achromatic light absorbing filter forming composition has light permeability, other factors such as mechanical strength, heat resistance, and insulation are also taken into consideration as appropriate. Above, what is necessary is just to select and use a thing according to a use. Specific examples of the transparent substrate include, for example, plates and sheets (or films; the same applies hereinafter) made of an organic material such as a resin, and plates made of an inorganic material such as glass.

As the transparent resin used as the plate and sheet made of the organic material, those described above for the transparent resin used for a normal transparent substrate can be used. In addition, these resins are used as a single or a plurality of types of mixed resins (including polymer alloys) as a resin material, and as a layer, they are used as a single layer or a laminate of two or more layers. In the case of a resin sheet, a uniaxially stretched or biaxially stretched sheet is more preferable in terms of mechanical strength.
Further, in the case of using a glass plate as a transparent substrate and forming a substantially achromatic light absorption filter on the glass plate, the glass includes quartz glass, borosilicate glass, soda lime glass, and the like, and more preferably Has a low coefficient of thermal expansion, excellent dimensional stability and workability in high-temperature heat treatment, and non-alkali glass that does not contain an alkali component in the glass, and can also be used as an electrode substrate such as a front substrate of a display. it can.

  In addition, the thickness of a transparent base material should just be a thing according to a use, and there is no restriction | limiting in particular. When it consists of transparent resin, it is about 12-1000 micrometers normally, Preferably it is 50-500 micrometers. On the other hand, when a transparent base material is a glass plate, about 1-5 mm is usually suitable. In any material, when the thickness is less than the above, the mechanical strength is insufficient and warping, loosening, breakage, and the like occur. When the thickness exceeds the above, the cost is increased due to excessive performance and it is difficult to reduce the thickness.

  The transparent substrate may also be used as a front substrate that is a constituent element of the display body. In addition, the transparent base material used for the front filter placed in front of the front substrate is thinner than a plate in terms of thinness and lightness, and is more resin than a glass plate in terms of not cracking. The sheet is excellent.

In this respect, a resin sheet is a preferable material for the transparent substrate, but among the resin sheets, in particular, polyester resin sheets such as polyethylene terephthalate and polyethylene naphthalate have transparency, heat resistance, cost, and the like. In view of this, a biaxially stretched polyethylene terephthalate sheet is more preferable. In addition, although the transparency of a transparent base material is so good that it is high, Preferably the light transmittance which becomes 80% or more by visible light transmittance | permeability is good.
The transparent substrate is appropriately subjected to known easy adhesion treatment such as corona discharge treatment, plasma treatment, ozone treatment, flame treatment, primer treatment, pre-heat treatment, dust removal treatment, vapor deposition treatment, alkali treatment, etc. May be.

  Next, an electromagnetic wave shielding function, a near infrared absorption function, a neon light absorption function, a color tone adjustment function, an ultraviolet absorption function, an antireflection function, an antiglare function, an antireflection function, which may be further laminated on the substantially achromatic light absorption filter. A single layer or two or more layers of filters or protective films (which may be collectively referred to as “functional filters”) having one or two or more functions of the scratch function and the antifouling function will be described in order.

[Electromagnetic wave shielding filter]
In the front filter for PDP of the present invention, the electromagnetic shielding filter that can be added to the substantially achromatic light absorbing filter or the laminate thereof shields electromagnetic waves generated from the plasma display. A metal mesh layer and a transparent conductive thin film layer are used for the electromagnetic wave shielding filter, but a metal mesh having high electromagnetic wave shielding properties is preferable. The metal mesh is obtained by laminating a metal foil on a transparent base material or other functional filter and forming a mesh by etching. The material used for the above-mentioned substantially achromatic light absorption filter can be used suitably for a transparent base material. An adhesive layer may be interposed between the base material and the metal mesh. When the adhesive layer is interposed, the adhesive layer is composed of an adhesive such as a polyester resin, a polyurethane resin, or an epoxy resin. As long as the metal mesh has an electromagnetic wave shielding function, the type of the metal is not particularly limited. For example, copper, iron, nickel, chromium, aluminum, gold, silver, stainless steel, tungsten, chromium, titanium In particular, copper is preferable. Examples of the copper foil include rolled copper foil and electrolytic copper foil, and the electrolytic copper foil is particularly preferable. By selecting the electrolytic copper foil, it is possible to achieve a good uniformity with a thickness of 10 μm or less, and to improve the adhesion with the blackened layer when blackened. Because you can.

  Here, in this invention, it is preferable that the one side or both surfaces of the said metal mesh are blackened. The blackening treatment is a treatment for blackening the surface of the metal mesh by coating with a thin film of copper oxide, blackened nickel, copper-cobalt alloy or the like. When applied to the front filter for PDP, this blackening treatment is performed. The conversion processing surface is usually arranged to be a surface on the viewer side. Since the external light on the surface of the metal mesh is absorbed by the copper oxide formed on the surface of the metal mesh by this blackening treatment, it is possible to prevent light from being scattered on the surface of the metal mesh.

The aperture ratio of the metal mesh is preferably as low as possible from the viewpoint of electromagnetic wave shielding ability. However, the aperture ratio is preferably 50% or more because the light transmittance decreases as the aperture ratio decreases.
Moreover, since the opening part and non-opening part of a metal mesh are uneven | corrugated, the planarizing layer formed so that transparent resin might fill the unevenness | corrugation of a metal mesh on the metal mesh, and the surface may be planarized May be laminated.

[Near infrared absorption filter]
As the near-infrared absorbing filter, a commercially available film having a near-infrared absorber (for example, Toyobo Co., Ltd., trade name No. 2832) is used, or a composition containing a near-infrared absorbing dye in a binder is formed, or This can be applied on a transparent substrate or other functional filter, and can be formed through drying, curing treatment, or the like, if necessary.

  As the near-infrared absorbing dye, a near-infrared region generated due to xenon gas discharge emitted from the plasma display panel, that is, a pigment that absorbs a wavelength region of 800 nm to 1100 nm is used. The near-infrared transmittance of the band is preferably 20% or less, more preferably 10% or less. At the same time, it is desirable that the near-infrared absorbing filter has a sufficient light transmittance in the visible light region, that is, in the wavelength region of 380 nm to 780 nm. Specific examples of near-infrared absorbing dyes include polymethine compounds, cyanine compounds, phthalocyanine compounds, naphthalocyanine compounds, naphthoquinone compounds, anthraquinone compounds, dithiol compounds, imonium compounds, diimonium compounds, Aminium compounds, pyrylium compounds, cerium compounds, squarylium compounds, copper complexes, nickel complexes, dithiol metal complexes organic near-infrared absorbing dyes, tin oxide, indium oxide, magnesium oxide, titanium oxide, oxidation It is possible to use one or more inorganic near infrared absorbing dyes such as chromium, zirconium oxide, nickel oxide, aluminum oxide, zinc oxide, iron oxide, ammonium oxide, lead oxide, bismuth oxide and lanthanum oxide in combination. it can.

  As the binder resin, a resin such as a polyester resin, a polyurethane resin, an acrylic resin, or an epoxy resin is used. Binder resin drying and curing methods include a drying and solidification method by drying a solvent (or dispersion medium) from a solution (or emulsion), a polymerization method using heat, ultraviolet light, electron beam energy, and a crosslinking reaction. Alternatively, a curing method utilizing a reaction such as crosslinking or polymerization between a functional group such as a hydroxyl group or an epoxy group in a resin and an isocyanate group in a curing agent can be applied.

[Neon light absorption filter]
The neon light absorption filter is installed to absorb neon light emitted from the plasma display panel, that is, an emission spectrum of neon atoms when the optical filter is used for a plasma display. Since the emission spectrum band of neon light has a wavelength of 550 to 640 nm, it is preferable to design the neon light absorption filter so that the spectral transmittance is 50% or less at wavelengths of 550 nm to 640 nm. The neon light absorption filter is made of a composition in which a dye that has been conventionally used as a dye having an absorption maximum in a wavelength region of at least 550 to 640 nm is dispersed in a binder resin as mentioned in the near infrared absorption filter. It can be formed into a film, or can be formed on a transparent substrate or other functional filter, and dried or cured as necessary. Specific examples of the dye include cyanine, oxonol, methine, subphthalocyanine or porphyrin. As the binder resin, resins such as those listed above for the near infrared absorption filter can be used.

[Color adjustment filter]
The color tone adjustment filter is used to adjust the color of the display filter to improve the color purity of the light emitted from the panel, the color reproduction range, the display color when the power is turned off, and the like. For example, a composition in which a color tone adjusting pigment is dispersed in a binder resin can be formed into a film, or can be formed on a transparent substrate or other functional filter, and dried or cured as necessary. it can. As the color tone adjusting dye, a known dye having a maximum absorption wavelength in the visible region of 380 to 780 nm can be used in combination with any dye according to the purpose. Examples of known dyes that can be used as the color tone adjusting dyes include the dyes described in JP 2000-275432 A, JP 2001-188121 A, JP 2001-350013 A, JP 2002-131530 A, and the like. Can be suitably used. In addition, other dyes such as anthraquinone, naphthalene, azo, phthalocyanine, pyromethene, tetraazaporphyrin, squarylium, and cyanine that absorb visible light such as yellow light, red light, and blue light. Can be used. As the binder resin, resins such as those listed above for the near infrared absorption filter can be used.

[Ultraviolet absorption filter]
In addition, as the ultraviolet absorption filter, for example, a composition in which an ultraviolet absorber is dispersed in a binder resin is formed, or this is applied onto a transparent substrate or other functional filter, and dried as necessary. It can be formed through a curing process or the like. Examples of the ultraviolet absorber include organic compounds such as benzotriazole and benzophenone, and inorganic compounds composed of particulate zinc oxide, cerium oxide, and the like. As the binder resin, resins such as those listed above for the near infrared absorption filter can be used.

[Antireflection filter]
Moreover, as an antireflection (AR) filter, for example, a multi-layer structure in which low refractive index layers and high refractive index layers are alternately laminated is generally used, and a dry method such as vapor deposition or sputtering, or coating is used. The wet method can also be used. Note that silicon oxide, magnesium fluoride, fluorine-containing resin, or the like is used for the low refractive index layer, and titanium oxide, zinc sulfide, zirconium oxide, niobium oxide, or the like is used for the high refractive index layer.

[Anti-glare filter]
In addition, anti-glare (AG) filters can be applied to the surface of the layer by forming a coating using an inorganic filler such as silica in a resin binder, or by shaping using a shaping sheet or shaping plate. It can be formed as a layer provided with fine irregularities that diffusely reflect. As the resin of the resin binder, a curable acrylic resin, an ionizing radiation curable resin, or the like is preferably used in the same manner as the hard coat layer described below because surface strength is desired as the surface layer.

[Hard coat layer]
The purpose of the hard coat layer (HC layer) is to improve the mechanical strength of the surface of the PDP front filter and to protect it from physical damage (scratch-proofing function, also referred to as scratch resistance). Provided. Examples of the hard coat layer include polyfunctional (meth) acrylate prepolymers such as polyester (meth) acrylate, urethane (meth) acrylate, and epoxy (meth) acrylate, or trimethylolpropane tri (meth) acrylate, pentaerythritol tetra An ionizing radiation curable resin in which a trifunctional or higher polyfunctional (meth) acrylate monomer such as (meth) acrylate, dipentaerythritol hexa (meth) acrylate or the like is used alone or in combination of two or more selected from these. It can be formed as a coating film used. Here, (meth) acrylate is a composite notation meaning acrylate or methacrylate.

[Anti-fouling layer]
The antifouling layer is generally a water-repellent or oil-repellent coat, and a siloxane-based, fluorinated alkylsilyl compound or the like can be applied. A fluorine-based or silicone-based resin used as a water-repellent paint can be preferably used. For example, when the low refractive index layer of the antireflection layer is formed of SiO ₂ , a fluorosilicate water-repellent paint is preferably used.
As a method for forming the above-described functional filter into a single layer, particles, pigments and the like necessary for expressing a desired function are mixed in a resin serving as a binder, and a melt extrusion method, a casting method, a calendar A known film forming method such as a method can be appropriately employed. In addition, as a method for forming the functional filter and the protective film coating film described above, a known layer forming method, for example, a coating method such as roll coating, comma coating, gravure coating, or partial formation in an arbitrary shape is easy. Printing methods such as screen printing and gravure printing can be appropriately employed.

Further, two or more of the substantially achromatic light absorbing filter and each functional filter may be bonded and laminated via an adhesive layer. For the adhesive layer, materials used in the above-described electromagnetic wave shielding sheet can be appropriately used. The shape of the substantially achromatic light absorbing filter, the functional filter, and the protective film may be a continuous belt shape or a single wafer shape depending on the method of lamination.
The method of adhering and laminating two or more filters via an adhesive layer is not particularly limited, and examples thereof include a method of adhering and laminating using a laminator having a pressure portion such as a pressure roll.
In addition, the manufacturing method of the front filter for PDP of this invention is not limited to the said embodiment.

Hereinafter, the present invention will be specifically described with reference to examples. These descriptions do not limit the present invention. In the examples, parts represent parts by weight unless otherwise specified.
<Example 1>
First, the pigment | dye (diimonium type | system | group) was added to the acrylic resin binder as black powder, adjusting the addition amount, and the coating film forming composition was obtained. This is coated on the easy-adhesion-treated surface side of a transparent biaxially stretched and easily-adhesive PET film having a thickness of 100 μm, and further dried, so that the transparent biaxially-stretched PET film (easy-adhesion-treated surface) A substantially achromatic light absorbing filter having a layer structure was obtained (the layers before and after / indicate that they are laminated and integrated). The obtained substantially achromatic light absorbing filter had a total light transmittance of 60%.

Next, a laminate having a layer structure of an adhesive layer / ultraviolet absorption filter / antireflection filter containing a near-infrared absorbing dye and a neon light absorbing dye was prepared.
As the ultraviolet absorbing filter, a Tetron film (trade name “HB type” manufactured by Teijin Ltd.), which is a transparent biaxially stretched PET film having a thickness of 50 μm and kneaded with an ultraviolet absorber, was used. The ultraviolet absorbing filter was also used as a base material for coating and forming an antireflection filter.

The antireflection filter was formed by sequentially forming a high refractive index layer and a low refractive index layer on the ultraviolet absorption filter.
Here, the high refractive index layer is a cured product having a thickness of 3 μm and a refractive index of 1.69 of a composition (trade name “KZ7973” manufactured by JSR Corporation) in which ultrafine zirconia particles are dispersed in an ultraviolet curable resin. Consists of layers.
The low refractive index layer is made of a cured product having a thickness of 100 nm and a refractive index of 1.41 made of a fluororesin ultraviolet curable resin (manufactured by JSR Corporation, trade name “TM086”).

Further, an adhesive layer is formed on the side opposite to the antireflection filter of the ultraviolet absorption filter, and the adhesive layer is formed by adding a near infrared absorber and a neon light absorber to the adhesive layer. Also used as near-infrared absorption filter and neon light absorption filter.
Cyanine dyes (trade name “TY-167” manufactured by Asahi Denka Kogyo Co., Ltd.) as neon light absorbers, and diimmonium dyes (trade name “CIR1085” manufactured by Nippon Carlit Co., Ltd.), phthalocyanines as near infrared absorbers. And a phthalocyanine dye (manufactured by Nippon Shokubai Co., Ltd., trade name “IR14”) were added.

As the adhesive, an acrylic resin-based pressure-sensitive adhesive (manufacturer: manufactured by Yodogawa Paper Mill, trade name: “TU-41A”) was used.
And it laminated | stacked mutually on the direction in which the light absorptive coating film side of the obtained substantially achromatic light absorption filter and the adhesive bond layer side of the laminate face each other. The PDP front filter of Example 1 was manufactured by stacking at this time.

<Example 2>
The same as in Example 1 except that the pigment (diimmonium-based) was added to the acrylic resin binder with the added amount adjusted so that the total light transmittance of the substantially achromatic light absorbing filter obtained was 40%. A front filter for PDP was obtained.

<Comparative Example 1>
The same as in Example 1 except that the dye (diimmonium-based) was added to the acrylic resin binder with the added amount adjusted so that the total light transmittance of the obtained substantially achromatic light absorbing filter was 70%. A front filter for PDP was obtained.
<Comparative example 2>
The same as in Example 1 except that the dye (diimmonium-based) was added to the acrylic resin binder with the added amount adjusted so that the total light transmittance of the obtained substantially achromatic light absorbing filter was 30%. A front filter for PDP was obtained.

[Performance evaluation method]
The following points were evaluated with respect to the front filter for PDP obtained in each of the above Examples and Comparative Examples. The evaluation results are shown in Table 1.
(1) Total light transmittance The total light transmittance of the obtained front filter for PDP was measured using a spectrophotometer (manufactured by Shimadzu Corporation, product number: “UV-3100PC”).

(2) Sensory evaluation (visual contrast evaluation, blackout evaluation, whitish evaluation)
The sensory evaluation of contrast is an image of a pattern in which grids (rectangular grids) are alternately arranged in two colors consisting of image data of the highest density of achromatic color (perfect black) and the lowest density of achromatic color (perfect white) Data (Figure 4) is displayed in PDP (Pioneer, product name “PDP-435HDL (42 inches)”, image quality (brightness and contrast) set to “standard” mode) All the filters of the example and the comparative example were placed side by side, and the quality was judged by whether or not the black and white boundary of the pattern was clearly visible. The case where the black-and-white border was clearly visible was marked with ○, and the case where it was not so was marked with ×.

  The sensory evaluation of blackout is based on the image data, achromatic gradation image data (FIG. 5) having a density of 15 levels obtained by dividing the area between complete black and complete white at 15 equal density intervals. Image data of various colors with 40 shades (Fig. 6), which is displayed with 8 shades of orange, yellow, green, blue, indigo, azure, and achromatic, changing the shade in 5 levels (Pioneer, product name “PDP-435HDL (42 inch)” image quality is set to “standard” mode) and the front filter for each PDP obtained in the example or comparative example is further arranged on the front. Installed and evaluated black crushing. Here, the concentration is defined as an amount proportional to the common logarithm of the reciprocal of the light intensity.

  The evaluation of the blackout is performed by visually observing the display of the image data displayed on the PDP through the filter, and in the display of the achromatic color gradation image data, the black of the darkest part and the black of the next density are displayed. Are visually indistinguishable, or in the display of the image data of the above-mentioned various colors, the highest density 7 chromatic colors and the highest density achromatic color (complete black on the data) cannot be discriminated. In this case, it was determined that “blackout” occurred, and “◯” was assigned when no blackening occurred, and “X” was indicated when blackening.

The sensory evaluation of white is judged as “white” if the whitening in the display portion of the above-mentioned achromatic gradation image data (FIG. 5) can be clearly discriminated and is not white Was marked with ◯, and a white one with x.
In addition, each above sensory evaluation was performed by evaluation of 20 evaluators. The criteria for each evaluation are as follows.

[Criteria]
○: When 11 or more evaluators are ○ ○: When 10 evaluators are ○ ×: When 9 or less evaluators are ○

<Summary of results>
In the front filter for PDP according to the present invention of Examples 1 and 2, the sensory evaluation results of contrast, blackout, and whitish were all within acceptable ranges.
On the other hand, the PDP front filter described in Comparative Example 1 in which the total light transmittance of the PDP front filter exceeds the range of the present invention did not show dark-colored black crushing, but had a black display. I was injured. As a result, the expression range (dynamic range) of the image gray scale is narrowed on the low density (white) side, and the contrast becomes insufficient.

  Further, the front filter for PDP described in Comparative Example 2 in which the total light transmittance of the front filter for PDP is less than the range of the present invention was not recognized as white at the time of black display. Crushing occurred. As a result, the expression range (dynamic range) of the image gray scale is narrowed on the high density (black) side, and the contrast becomes insufficient.

It is sectional drawing of an example of the front filter for PDP which concerns on this invention. It is sectional drawing of an example of the front filter for PDP which concerns on this invention. It is sectional drawing of an example of the front filter for PDP which concerns on this invention. 3 shows image data for sensory evaluation of contrast of the front filter for PDP according to the present invention. The image data for the sensory evaluation of black crushing and whitishness of the front filter for PDP according to the present invention is shown. 3 shows image data for sensory evaluation of blackout of the front filter for PDP according to the present invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Transparent base material 2 Substantially achromatic light absorption filter 3 Electromagnetic wave shielding filter 4 Flattening layer 5 Near-infrared absorption filter 6 Antireflection filter

Claims (2)

  A front filter for PDP which contains at least a substantially achromatic light absorption filter and has a total light transmittance of 15 to 35%.   Electromagnetic wave shielding function, near infrared absorption function, neon light absorption function, color tone adjustment function, ultraviolet absorption function, antireflection function, antiglare function, anti-scratch function, and antifouling function The front filter for PDP according to claim 1.

Images