JP2004198978A - Luminance-enhancing sheet for plasma display panel, and the plasma display panel system using the sheet - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a luminance-enhancing sheet for PDP, capable of easily enhancing brightness of the visible light, and the PDP device using the same. <P>SOLUTION: The luminance-enhancing sheet formed of a laminate for use in front of the plasma display panel an adhesive agent layer is provided on the outer layer of the laminate, and a light transmissive layer having an uneven surface on the outermost surface, the other surface of which faces the adhesive agent layer is provided. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a brightness enhancement sheet for a plasma display panel (hereinafter, referred to as PDP) used for various thin display panels, and a PDP device using the same.
[0002]
[Prior art]
The PDP can drastically reduce the depth as compared with a CRT direct-view display device or a rear-projection display device, and is expected as a promising means for realizing a wall-mounted large-screen television in the future.
[0003]
FIG. 8 is a perspective view showing a configuration of the PDP, and FIG. 9 is a sectional view thereof. 1 is a front glass, 2 is a rear glass, 3 is a partition, 4 is an address electrode, 5R, 5G, and 5B are phosphors, 6 is a display electrode, 7 is a dielectric layer, and 8 is a protective film. However, hatching representing a cross section may be omitted in the drawings in this specification.
[0004]
The PDP 11 has a configuration in which a front glass 1 and a rear glass 2 face each other while sandwiching a partition wall 3.
[0005]
A display electrode 6 is formed inside the front glass 1 and an address electrode 4 is formed inside the rear glass 2 by photo-etching or the like. The display electrodes 6 formed inside the front glass 1 and the address electrodes 4 formed inside the rear glass 2 are arranged so as to be orthogonal to each other.
[0006]
The display electrode 6 on the front glass 1 is covered with a dielectric layer 7 having a predetermined thickness formed by printing and firing low-melting glass, and a protective film 8 is formed thereon.
[0007]
On the back glass 2, the partition walls 3 are stacked by thick film printing for each address electrode 4, and the space between the adjacent partition walls 3 forms a cell. The phosphors 5R, 5G, and 5B are applied so as to cover the address electrodes 4, respectively.
[0008]
Further, in the cell space, a discharge gas mainly composed of neon mixed with xenon of several volume% is sealed, so that each cell forms a discharge cell.
[0009]
A discharge cell is located at each intersection of the orthogonal address electrode 4 and display electrode 6, and each discharge cell forms a pixel. Therefore, a plurality of pixels are arranged in a matrix.
[0010]
In the PDP 11 configured as described above, when a voltage is applied to the address electrode 4 and the display electrode 6 at an appropriate timing, discharge occurs in a discharge cell, and ultraviolet rays are generated by xenon gas. An image can be displayed by emitting visible light from the phosphor 5 excited by the ultraviolet light.
[0011]
However, the principle of light emission of the PDP 11 is basically the same as that of a fluorescent lamp. By generating glow discharge, ultraviolet light is generated from xenon gas, and the phosphor 5 is excited to emit light. The conversion efficiency of the phosphor into visible light is said to be low. Further, in FIG. 9, as indicated by an arrow in the trajectory of the visible light emitted from the phosphor 5, the refractive index of the front glass 1 is higher than the refractive index of air, so that the interface between the front glass 1 and air is increased. Due to refraction, there is visible light that cannot be emitted due to total internal reflection, or visible light that is dissipated in an oblique horizontal direction. As described above, since visible light cannot be effectively extracted to the outside, it is difficult to obtain high luminance as in a fluorescent lamp, and currently only about 0.2% is finally used.
[0012]
For this reason, as a method of obtaining high luminance, there is a method of making the surface of the display electrode uneven (for example, see Patent Document 1). In this case, the main purpose is to improve the heat radiation, and it is said that the improvement of the luminance has also been achieved with the improvement of the heat radiation, but there was no effect on the improvement of the luminance.
[0013]
Therefore, at present, there is no fundamental measure for obtaining a high luminance.
[0014]
[Patent Document 1]
JP-A-2002-117770
[0015]
[Problems to be solved by the invention]
Then, the inventors of the present invention diligently studied the above problem, and produced a laminate having an uneven surface, and by attaching such a laminate to the front surface of the PDP, radiation by the phosphor was performed. It has been found that the visible light can be sufficiently utilized and the luminance can be easily improved. That is, an object of the present invention is to provide a brightness enhancement sheet for PDP, which can easily improve brightness of visible light, and a PDP device using the same.
[0016]
[Means for Solving the Problems]
In order to achieve the above object, the present invention provides a brightness enhancement sheet for a plasma display panel comprising a laminate used on the front surface of a plasma display panel, wherein the outermost layer on the plasma display panel side of the laminate has an adhesive. A light transmitting layer having an uneven surface is provided on the outermost layer on the side opposite to the side where the pressure-sensitive adhesive layer of the laminate is provided.
[0017]
When adhered to the front surface of the PDP by the pressure-sensitive adhesive layer, it is possible to control the emission light characteristics from the brightness enhancement sheet for the PDP by the light transmission layer having the uneven surface, and to reduce the visible light emitted by the phosphor. Can be fully utilized. That is, by controlling the shape of the uneven surface, the refractive index, and the like, the visible light emitted from the brightness enhancement sheet for PDP can be converged or diffused within a desired angle range. The luminance of visible light can be improved.
[0018]
Furthermore, since the pressure-sensitive adhesive layer is present between the PDP brightness enhancement sheet and the PDP, there is no air layer, so that visible light or oblique light that cannot be emitted due to total reflection due to refraction at the interface between glass and air cannot be emitted. The visible light that is dissipated in the lateral direction can be reduced and can be emitted to the light transmitting layer.
[0019]
Further, since the PDP brightness enhancement sheet can be directly adhered to the PDP, the step of applying an adhesive or the like can be omitted, so that the PDP device can be easily assembled.
[0020]
It is preferable that the pressure-sensitive adhesive layer has a refractive index of 1.4 or more and 1.7 or less. If the refractive index is less than 1.4, the reflection of visible light from the glass increases, while if the refractive index exceeds 1.7, no visible light is emitted to the light transmitting layer.
[0021]
Further, it is preferable that the uneven surface has a semi-elliptical spherical concave portion and / or a semi-elliptic spherical convex portion having a ratio of a major axis length to a minor axis length of 1 or more and 3 or less.
[0022]
The “irregular surface” means that the surface is not composed of only a surface perpendicular to the normal direction of the emitted light (hereinafter, referred to as “flat”), and has a prism-like shape having a triangular cross section. The triangular cross section is not particularly limited, and may have an isosceles or unequal sides, but preferably has a surface structure such as a spherical surface or a cylindrical side surface. The “irregular surface portion” means one of the uneven portions formed on the concave and convex surface. The light transmitting layer constituting the present invention may or may not have a flat portion between the uneven surface portions. Such a flat portion allows visible light to pass through without being diffused. Therefore, the emission light characteristics can be more controlled by adjusting the area ratio between the uneven surface portion and the flat portion. Further, the uneven surface is formed of a fixed size or various sizes, may be configured only with a convex portion, may be configured only with a concave portion, or may be configured with a mixture of a convex portion and a concave portion. May be done. It should be noted that even when elliptical spherical beads or the like are contained, an uneven interface exists, so that the surface has an uneven surface.
[0023]
Also, the “semi-ellipse” does not mean that it is the positive half of the ellipse, but it is sufficient if it is equal to or less than half the ellipse. Thereby, the effect of the present invention can be obtained. Further, a circle having a ratio of the major axis length to the minor axis length of 1 is included, and the object of the present invention can be achieved as long as the shape is not limited to a regular ellipse but is apparently elliptical. Therefore, even a partial shape of a sine curve or a parabola is included in the scope of the present invention.
[0024]
Here, a method of controlling the emission light characteristics from the brightness enhancement sheet for PDP will be described with reference to FIGS. FIG. 6 is a diagram showing a locus of visible light from the light transmitting layer having a semi-elliptical concave surface formed thereon, and FIG. 7 is a diagram showing visible light from a light transmitting layer having a semi-elliptical convex surface formed thereon. FIG.
[0025]
In FIG. 6, the major axis direction of the ellipse of the major axis a and the minor axis b is directed to the normal direction of the emitted light in the light transmitting layer 41, and the length of the major axis a is measured from the end of the major axis. 80%, a concave surface portion cut out in a shape cut by a plane perpendicular to the long axis is formed.
[0026]
The trajectory of the visible light is indicated by an arrow.
[0027]
Here, the refractive index of air is n₁, Refraction angle θ₁And the refractive index of the light transmitting layer 41 is n_Two, Incident angle θ_TwoThen, the relationship of Expression (1) is satisfied.
[0028]
n₁sin θ₁= N_Twosin θ_Two        (1)
That is, the visible light from the normal direction is incident on the concave surface at an incident angle θ._TwoAnd the refraction angle θ₁Will be released. In general, the refractive index n of air₁Is the refractive index n of the light transmitting layer_TwoThe visible light is diffused and emitted by the concave portion.
[0029]
Therefore, the refractive index n of the light transmitting layer 41_TwoIs controlled so as to increase the refraction angle θ₁Is increased, and as a result, the emission range of visible light can be increased.
[0030]
Further, when visible light from the normal direction is incident on the flat part, the light goes straight. That is, when a flat portion is provided between the concave portions, the visible light converges in the normal direction of the flat portion.
[0031]
Next, FIG. 7 shows that the major axis direction of the ellipse of the major axis a and the minor axis b is directed to the normal direction of the emitted light on the light transmitting layer 42, and the major axis a At the position of 80% of the length of the surface, a convex portion cut in a plane perpendicular to the long axis is formed.
[0032]
The trajectory of the visible light is indicated by an arrow.
[0033]
Here, the refractive index of air is n_Three, Refraction angle θ_ThreeAnd the refractive index of the light transmitting layer 42 is n_Four, Incident angle θ_FourThen, a relationship similar to the expression (1) is satisfied.
[0034]
That is, the visible light from the normal direction is incident on the convex surface at an incident angle θ._FourAnd the refraction angle θ_FourWill be released. In general, the refractive index n of air_ThreeIs the refractive index n of the light transmitting layer 42_FourTherefore, the visible light is converged and emitted by the convex portion.
[0035]
Therefore, the refractive index n of the light transmitting layer 42_FourIs controlled to be large, the refraction angle θ_ThreeIs increased, and as a result, the emission range of visible light can be reduced.
[0036]
Further, when visible light from the normal direction is incident on the flat part, the light goes straight.
[0037]
As described with reference to FIGS. 6 and 7, the emission light characteristics can be controlled by controlling the shape of the semi-elliptical uneven surface, the refractive index, and the area ratio with the flat portion.
[0038]
Also, the emission light characteristics can be controlled by controlling the position of the uneven surface portion, the ratio of the major axis length to the minor axis length, and the height and depth of the uneven surface portion.
[0039]
At this time, the ratio of the major axis length to the minor axis length is set to 1 or more and 3 or less. If it exceeds 3, refraction becomes too large, and it becomes difficult to control emission light characteristics.
[0040]
Therefore, if the semi-elliptical spherical concave portion and / or the semi-elliptical spherical convex portion having such a ratio of the major axis length to the minor axis length of 1 to 3 is formed, the PDP becomes The light emitted from the brightness enhancement sheet can be converged or diffused in a desired angle range in the front-rear direction and the left-right direction.
[0041]
Further, the uneven surface formed on the light transmitting layer has a semi-elliptic cylindrical concave portion and / or a semi-elliptic cylindrical convex portion in which a ratio of a major axis length to a minor axis length is 1 or more and 3 or less. It is also preferred to have
[0042]
With such a configuration, light emitted from the brightness enhancement sheet for PDP can be converged or diffused in only one of the front-back direction and the left-right direction within a desired angle range.
[0043]
It is also preferable that the light transmitting layer is formed by dispersing a large number of beads in a binder.
[0044]
With such a configuration, it is possible to form a concave-convex surface portion without requiring a complicated manufacturing tool, and to impart good light transmission and light diffusion to light emitted from the brightness enhancement sheet for PDP.
[0045]
Further, it is preferable that the large number of beads are composed of beads completely embedded in the binder and / or beads partially embedded in the binder.
[0046]
The difference between the refractive index of the beads and the refractive index of the binder is preferably 0.01 or more and 0.15 or less.
[0047]
Furthermore, a plasma display panel device can be configured using the above-described brightness enhancement sheet for a plasma display panel.
[0048]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
[0049]
It should be noted that a PDP device using the PDP brightness enhancement sheet alone or a PDP device using the PDP brightness enhancement sheet also corresponds to the invention.
[0050]
FIG. 1 is a sectional view showing an example of an embodiment of the PDP device of the present invention, FIG. 2 is a front view thereof, 11 is a PDP, and 21 is a brightness enhancement sheet for a PDP.
[0051]
The above-described PDP 11 is mounted in a housing of a PDP device (not shown), and a PDP brightness enhancement sheet 21 is mounted on the front glass side of the PDP 11 in the housing.
[0052]
The PDP brightness enhancement sheet 21 is a laminate, 30 is an adhesive layer, and 32 is a light transmitting layer. These members are integrated to constitute a PDP brightness enhancement sheet 21.
[0053]
In FIG. 1, a PDP brightness enhancement sheet 21 is adhered and fixed to the surface of the front glass of the PDP 11 by an adhesive layer 30.
[0054]
Further, a light transmitting layer 32 is provided on a surface of the adhesive layer opposite to the PDP 11 (hereinafter, referred to as a front surface).
[0055]
As shown in FIGS. 1 and 2, a large number of semicircular concave portions are irregularly formed in the light transmitting layer 32 at the interface with air. In addition, a flat portion is formed between the semicircular concave portion and the semicircular concave portion.
[0056]
In the above configuration, as shown by an arrow in the trajectory of the light emitted from the phosphor 5, the refractive index of the front glass 1 is lower than the refractive index of the pressure-sensitive adhesive layer. The visible light emitted from the phosphor 5 can be emitted to the light transmission layer 32 by reducing visible light that cannot be emitted or visible light that is dissipated in the oblique horizontal direction.
[0057]
Further, the visible light transmitted from the pressure-sensitive adhesive layer 30 is emitted from the light transmission layer 32 having the semicircular concave portion. At this time, the light is uniformly and isotropically diffused within a desired angle range by utilizing the light diffusion effect of the semi-elliptical spherical concave portion as described above.
[0058]
Therefore, the visible light emitted from the phosphor 5 can be sufficiently used, and the luminance of the visible light can be improved.
[0059]
Further, since the PDP brightness enhancement sheet 21 can be directly adhered to the PDP 11, the step of applying an adhesive or the like can be omitted, so that the PDP device can be easily assembled.
[0060]
Further, the shape of the light transmitting layer constituting the present invention may be as follows.
[0061]
FIG. 3 is a perspective view showing a part of another example of the light transmitting layer in the present invention.
[0062]
In FIG. 3A, a large number of convex portions are formed in the light transmitting layer 43 in such a manner that a cylindrical shape having a radius a and a height c is cut along a plane parallel to the central axis at a central axis thereof. are doing.
[0063]
In FIG. 3B, the light transmitting layer 44 cuts out the sphere having the radius a in half, and further cuts the sphere having the radius a in half. A large number of concave portions are formed.
[0064]
In FIG. 3C, in the light transmitting layer 45, the minor axis direction of the elliptical sphere having the major axis a and the minor axis b is oriented in the normal direction of the emission light, and the height d is measured from the minor axis end. A large number of concave portions are cut out in a shape cut at a position perpendicular to the short axis at the position.
[0065]
The thickness of the light transmitting layer is not particularly limited, but is, for example, 10 to 500 μm, and preferably 75 to 250 μm. Note that the thickness of the light transmitting layer is the thickness of a portion where the uneven surface portion is not formed.
[0066]
The height and / or depth of the uneven surface portion is not particularly limited, and is preferably set to a value in the range of 0.5 to 10 μm. If the height and / or depth of the uneven surface portion exceeds 10 μm, it is easily broken, and if the height and / or depth of the uneven surface portion is less than 0.5 μm, it becomes difficult to control the emission light characteristics. .
[0067]
Further, the radius of curvature of the uneven surface portion is not particularly limited, and is preferably set to a value within a range of 1 to 30 μm. Even if the radius of curvature of the uneven surface portion exceeds 30 μm or more and is less than 1 μm, it becomes difficult to control emission light characteristics. In the case where the concave-convex surface portion has an elliptical shape, the radius of curvature of the concave-convex surface portion is an average value of the major axis and the minor axis.
[0068]
The area occupied by the uneven surface portion on the front surface of the light transmitting layer is not particularly limited, and is preferably 60 to 90%. If the area occupied by the uneven surface portion exceeds 90%, the production is difficult, and it is easy to break. If the area occupied by the uneven surface portion is less than 60%, it becomes difficult to control the emission light characteristics.
[0069]
Further, it is preferable not to form a structure in which the visible light incident on the uneven surface portion from the normal direction of the emitted light is totally reflected and is not transmitted therethrough.
[0070]
The light-transmitting layer must be selected so as to sufficiently transmit visible light to the extent that it does not hinder the use of each application, and is most preferably colorless and transparent. It may be transparent. The light transmitting layer is not particularly limited, for example, polymethyl methacrylate, a homo- or copolymer of acrylate or methacrylate such as polymethyl acrylate, polyethylene terephthalate, polyester such as polybutylene terephthalate, Thermoplastic resins such as polycarbonate, polystyrene and polymethylpentene, or acrylates such as polyfunctional urethane acrylates and polyester acrylates cross-linked by ultraviolet rays or electron beams, transparent resins such as unsaturated polyesters, polyolefins, cellulose acetate, and weather-resistant vinyl chloride And transparent ceramics such as transparent glass.
[0071]
As a method of forming an uneven surface on the light transmitting layer,
(A) a method in which a synthetic resin is laminated on a sheet mold having a shape obtained by inverting the irregular surface shape, and the sheet mold is peeled off to form an irregular surface on the surface;
(B) an injection molding method of injecting a molten resin into a mold having an inverted shape of an uneven surface,
(C) a method of transferring the shape by reheating the sheeted resin, pressing the same between the metal mold and the metal plate and pressing the same.
(D) an extruded sheet molding method in which a molten sheet-like resin is passed through a nip between a roll having an inverted shape of the concavo-convex surface and another roll, and the shape is transferred,
(E) A UV curable resin is applied to a base sheet or the like, pressed onto a roll having the same inverted shape as above, and the shape is transferred to the uncured UV curable resin, and then the UV curable resin is cured by applying ultraviolet rays. How to make
(F) There is a method of using an EB curing resin instead of the UV curing resin.
[0072]
Next, the pressure-sensitive adhesive layer will be described.
[0073]
The pressure-sensitive adhesive layer is not particularly limited as long as it has a refractive index of 1.4 or more and 1.7 or less, and includes acrylic, rubber, and polyester-based adhesives. Is preferred. Acrylic pressure-sensitive adhesives include, as a main monomer for imparting appropriate wettability and flexibility as a pressure-sensitive adhesive, a (meth) acrylic acid alkyl ester having a glass transition point of −10 ° C. or less when polymerized. One or two or more, and if necessary, a functional group-containing monomer such as acrylic acid, methacrylic acid, or 2-hydroxyethyl acrylate, and another copolymerizable monomer are appropriately dissolved using a polymerization catalyst. An acrylic polymer obtained by polymerization by a polymerization method, an emulsion polymerization method, a bulk polymerization method (particularly, a polymerization method using ultraviolet light), a suspension polymerization method, or the like, to which various additives such as a crosslinking agent are added is used. . A thermal crosslinking type, a light (ultraviolet ray, electron beam) crosslinking type, or the like may be used.
[0074]
Further, the thickness of the pressure-sensitive adhesive layer is 10 to 500 μm, and more preferably 25 to 300 μm. If the thickness of the pressure-sensitive adhesive layer exceeds 500 μm, the thickness of the PDP device cannot be reduced, and if the thickness of the pressure-sensitive adhesive layer is less than 10 μm, an external impact is transmitted to the front glass of the PDP 11 and cracks are generated. Failure may occur.
[0075]
The elastic modulus of the pressure-sensitive adhesive layer is 1 × 10^Five ~ 1 × 10⁷dyn / cm^TwoIt is preferable that Within this range, even if an external impact is applied, the pressure-sensitive adhesive layer absorbs the impact, so that the PDP is not easily scratched and the glue thickness is instantaneously reduced, but the self-recovery occurs immediately. Then, the smooth surface is restored as if there was nothing. In addition, when directly adhered to the PDP, it absorbs undulations on the PDP surface, and the lamination becomes good.
[0076]
Next, a mode in which the light transmitting layer is formed by dispersing a large number of beads in a binder will be described.
[0077]
FIG. 4 is a sectional view showing another example of the embodiment of the PDP device of the present invention, wherein 11 is a PDP, and 54 is a brightness enhancement sheet for PDP.
[0078]
The above-described PDP 11 is mounted in a housing of a PDP device (not shown), and a PDP brightness enhancement sheet 54 is mounted on the front glass 1 side of the PDP 11 in the housing.
[0079]
The PDP brightness enhancement sheet 54 is a laminate, 50 is an adhesive layer, 51 is a base film, 58 is a binder, and 59 is beads. These members are integrated to constitute a PDP brightness enhancement sheet 54.
[0080]
In FIG. 4, a PDP brightness enhancement sheet 54 is adhered and fixed to the front glass surface of the PDP 11 by an adhesive layer 50.
[0081]
Further, on the surface of the pressure-sensitive adhesive layer opposite to PDP 11, a light transmitting layer 57 composed of a film substrate 51, a binder 58 and beads 59 is provided in this order.
[0082]
The light transmitting layer 57 is formed by completely or partially embedding beads 59 of various particle sizes in the binder 58.
[0083]
FIG. 5 is a cross-sectional view showing a part of another example of the light transmitting layer constituting the present invention.
The light transmitting layer 63 is formed by completely burying beads 62 having a uniform particle size in the binder 61.
[0084]
In the above configuration, as shown by an arrow in the trajectory of the light emitted from the phosphor 5, the refractive index of the front glass 1 is lower than the refractive index of the pressure-sensitive adhesive layer. Visible light emitted from the phosphor 5 can be emitted to the light transmission layer 57 by reducing visible light that cannot be emitted and visible light that is dissipated obliquely in the horizontal direction.
[0085]
Further, the visible light transmitted from the pressure-sensitive adhesive layer 50 is reflected and / or refracted by the beads 62 dispersed in the binder 61, and is emitted from the light transmitting layer 57.
At this time, the visible light is uniformly and isotropically diffused by repeating reflection and / or refraction.
[0086]
Therefore, the visible light emitted from the phosphor 5 can be sufficiently used, and the luminance of the visible light can be improved.
[0087]
Further, since the PDP brightness enhancement sheet 54 can be directly adhered to the PDP 11, the step of applying an adhesive or the like can be omitted, so that the PDP device can be easily assembled.
[0088]
The thickness of the light transmitting layers 57 and 63 is not particularly limited, but may be 10 to 500 μm in consideration of the difficulty of application to the base film, strength, light diffusivity, and the like. preferable.
[0089]
Examples of the binder include a polyester resin, an acrylic resin, a polystyrene resin, a polyvinyl chloride resin, a polyvinylidene chloride resin, a polyethylene resin, a polypropylene resin, a polyurethane resin, a polyamide resin, and a polyvinyl acetate resin. Polyvinyl alcohol resin, epoxy resin, cellulose resin, organosiloxane resin, polyimide resin, polysulfone resin, polyarylate resin, and the like can be used. Among them, polyester resins are particularly preferable in terms of controllability, wettability, adhesion to the film substrate 51, and scratch resistance, light resistance, transparency, and the like of the resin itself.
[0090]
Examples of the beads include methacrylate polymers, typical examples include methyl methacrylate, ethyl methacrylate, propyl methacrylate, and butyl methacrylate.Also, acrylate polymers, and typical examples include methyl acrylate, ethyl acrylate, n-propyl acrylate, and isopropyl Acrylate, butyl acrylate, etc., average particles obtained by polymerizing styrene, vinyl toluene, α-methyl styrene, halogenated styrene, etc. as aromatic vinyl monomers and further polymerizing allyl methacrylate, triallyl cyanurate, etc. as crosslinkable monomers It is a polymer having a diameter of 1 to 50 μm, preferably a polymer having an average particle diameter of 3 to 10 μm, and these beads may be used alone or in combination of two or more.
[0091]
The beads may be not only solid beads but also hollow beads.
[0092]
The hollow beads are those containing air in the beads, and any of shell walls made of an inorganic material or organic materials can be used.Examples of the inorganic materials include silica hollow beads and glass. Examples of the organic substance include hollow beads and the like. A balloon in which a low-boiling hydrocarbon is microencapsulated with a shell wall of a polymer having good gas barrier properties can be used. It is also preferable to use these hollow beads made of an inorganic substance and hollow beads made of an organic substance in combination.
[0093]
Preferable examples of the hollow beads made of an organic material include acrylonitrile simple resin, a balloon having a shell wall made of a copolymer of acrylonitrile and vinylidene chloride, and a microcapsulated balloon having a low boiling point, and having a particle size. Thermal expansion microspheres having a size of 4 to 8 μm are exemplified.
[0094]
On the other hand, the hollow beads made of an inorganic material are preferably in the range of 20 to 80 μm in terms of excellent strength and more air layers. If it exceeds 80 μm, uniform coating becomes difficult, and the total thickness becomes undesirably large.
[0095]
The advantage of using the hollow beads is that the beads themselves contain air and are excellent in light diffusion effect.
[0096]
As the above-mentioned beads, hollow beads, solid beads, beads made of an inorganic substance, and beads made of an organic substance may be used alone or in combination.
[0097]
Further, the beads are preferably mixed and dispersed in 50 to 500 parts by weight with respect to 100 parts by weight of the binder.
[0098]
The difference between the refractive index of the binder and the refractive index of the beads is preferably 0.01 or more and 0.15 or less.
[0099]
In addition, in the form in which the light transmitting layer is one in which a large number of beads are dispersed in a binder, a film substrate is provided.However, the film substrate is made of polycarbonate or polycarbonate from the viewpoint of transparency, light resistance, and coating suitability. It is preferable to use polyethylene terephthalate, and the thickness of the film substrate is preferably 50 to 200 μm from the viewpoint of easy handling.
[0100]
As a method for forming the light transmitting layer on the film substrate, a dipping method, a curtain flow method, a roll coating method, a knife coating method, or the like can be used.
[0101]
The pressure-sensitive adhesive layer may be the same as described above.
[0102]
Although the main part of the present invention has been described above, between the light transmitting layer and the pressure-sensitive adhesive layer, while preventing reflection in a wide wavelength range and adjusting the optical path of visible light, a layer whose refractive index has been adjusted. May be formed in several layers.
[0103]
For example, by laminating layers having a higher refractive index in order from the pressure-sensitive adhesive layer, reflection in a wide wavelength range can be prevented, and visible light can be incident on the light transmitting layer from the normal direction.
[0104]
Further, a layer or the like for protecting the uneven surface of the light transmitting layer may be formed with a different refractive index from the light transmitting layer.
[0105]
For example, since the concave portion is easily damaged and attaches dust and the like, a material that fills the concave portion may be formed.
[0106]
Furthermore, in the brightness enhancement sheet for PDP of the present invention, the laminate preferably has at least one function of reducing unnecessary radiation, cutting off infrared rays, and adjusting light transmittance. This is because electromagnetic waves and / or infrared rays can be prevented from going outside. Also, high contrast can be achieved.
[0107]
The brightness enhancement sheet for PDP of the present invention may be provided with a hard coat layer, an antistatic layer or an intermediate layer. The hard coat layer preferably contains a cross-linked polymer. The hard coat layer can be formed using an acrylic, urethane, epoxy, or siloxane-based polymer, oligomer, or monomer (eg, an ultraviolet curable resin). A silica-based filler can be added to the hard coat layer.
[0108]
Various layers in the brightness enhancement sheet for PDP of the present invention, that is, the pressure-sensitive adhesive layer and the like can be formed by a general coating method. Examples of the coating method include a dip coating method, an air knife coating method, a curtain coating method, a roller coating method, a wire bar coating method, a gravure coating method, and the like. Two or more layers may be formed by simultaneous coating. In addition, as a method for forming a layer in the brightness enhancement sheet for a PDP of the present invention, a sputtering method, a vacuum evaporation method, an ion plating method, a plasma CVD method, or a PVD method can be appropriately selected.
[0109]
The brightness enhancement sheet for PDP of the present invention is used for an image display device such as a liquid crystal display (LCD), a plasma display panel (PDP), an electroluminescence display (ELD), and a cathode ray tube display (CRT). In particular, a remarkable effect can be obtained by using the brightness enhancement sheet for PDP of the present invention in a plasma display panel (PDP) and its PDP device.
[0110]
【Example】
Hereinafter, the present invention will be described in detail with reference to examples. However, it is needless to say that the present invention should not be limitedly interpreted based on the description of the examples.
[0111]
(Example 1)
(1) Formation of light transmission layer 32 (see FIG. 1)
A take-up roll of a colorless and transparent biaxially stretched polyethylene terephthalate substrate sheet having a thickness of 100 μm was prepared.
[0112]
(2) A roll-shaped relief plate having a hemispherical shape engraved on the surface of a metal cylinder is prepared, and an ultraviolet-curable resin liquid is supplied to the plate surface from a T-die nozzle while rotating the plate around a central axis. The surface of the reverse mold was filled and coated.
[0113]
The ultraviolet-curable resin liquid is a mixture of a polyfunctional polyester acrylate oligomer and a photoreaction initiator.
[0114]
(3) Next, the base sheet is unwound from the take-up roll at a speed synchronized with the rotational peripheral speed of the roll-shaped relief plate, and the base sheet is laminated on the roll relief plate by a pressing roll with the resin liquid interposed therebetween. In this state, ultraviolet rays from a mercury lamp were irradiated from the substrate sheet side, and the resin liquid was cross-linked and cured in the inverted mold and simultaneously adhered to the substrate sheet.
[0115]
(4) Next, the base sheet running using the peeling roll was peeled off together with the cured resin formed in a cutout shape of the hemispherical shape adhered thereto, thereby obtaining the light transmitting layer 32.
[0116]
The shape on the front side of the light transmitting layer 32 is as follows.
Hemispherical concave surface
・ Radius = 20 μm
・ Depth = 8μm
・ Concave part / flat part = 80/20
(5) Formation of pressure-sensitive adhesive layer 30
An adhesive surface of a 38 μm-thick polyethylene terephthalate film coated with a 25 μm-thick acrylic pressure-sensitive adhesive is closely adhered to the rear surface of the light transmitting layer 32 and laminated to have an adhesive layer 30 and protect the surface. A PDP brightness enhancement sheet 21 of the present invention provided with a film (not shown) was produced.
[0117]
(Evaluation of brightness enhancement sheet for PDP)
The PDP 11 was attached to the PDP 11 by attaching the PDP brightness enhancement sheet prepared in Example 1 to the PDP 11 by the adhesive layer 30. Then, it was confirmed that, in the PDP brightness enhancement sheet of Example 1, the image became brighter than before the PDP 11 was attached to the PDP brightness enhancement sheet.
[0118]
【The invention's effect】
As described above, according to the present invention, when adhered to the front surface of a PDP by the pressure-sensitive adhesive layer, the light-transmitting layer having the uneven surface controls the emission light characteristics from the brightness enhancement sheet for the PDP. And the visible light emitted by the phosphor can be sufficiently utilized. That is, by controlling the shape of the uneven surface, the refractive index, and the like, the visible light emitted from the brightness enhancement sheet for PDP can be converged or diffused within a desired angle range. The luminance of visible light can be improved.
[0119]
Furthermore, since the pressure-sensitive adhesive layer is present between the PDP brightness enhancement sheet and the PDP, there is no air layer, so that visible light or oblique light that cannot be emitted due to total reflection due to refraction at the interface between glass and air cannot be emitted. The visible light that is dissipated in the lateral direction can be reduced and can be emitted to the light transmitting layer.
[0120]
Further, since the PDP brightness enhancement sheet can be directly adhered to the PDP, the step of applying an adhesive or the like can be omitted, so that the PDP device can be easily assembled.
[Brief description of the drawings]
FIG. 1 is a sectional view showing an example of an embodiment of a PDP device of the present invention.
FIG. 2 is a front view showing the PDP device shown in FIG.
FIG. 3 is a perspective view showing a part of another example of the light transmitting layer constituting the present invention.
FIG. 4 is a sectional view showing another example of the embodiment of the PDP device of the present invention.
FIG. 5 is a cross-sectional view showing a part of another example of the light transmitting layer constituting the present invention.
FIG. 6 is a diagram showing a locus of visible light from a light transmitting layer having a semi-elliptical concave portion.
FIG. 7 is a diagram showing a locus of visible light from a light transmitting layer on which a semi-elliptical convex portion is formed.
FIG. 8 is a perspective view showing a configuration of a PDP.
FIG. 9 is a sectional view showing the conventional PDP shown in FIG.
[Explanation of symbols]
1 front glass
2 Back glass
3 partition
4 Address electrode
5 phosphor
6 Display electrode
7 Dielectric layer
8 Protective film
11 PDP
21,54 Brightness improving sheet for PDP
30, 50 adhesive layer
32, 41, 42, 43, 44, 45, 57, 63 Light transmitting layer
51 Film substrate
58, 61 binder
59, 62 beads

Claims (8)

A brightness enhancement sheet for a plasma display panel comprising a laminate used on the front surface of the plasma display panel,
An adhesive layer is provided on the outermost layer on the plasma display panel side of the laminate,
A brightness enhancement sheet for a plasma display panel, wherein a light transmission layer having an uneven surface is provided on the outermost layer on the opposite side of the laminate from the side where the pressure-sensitive adhesive layer is provided. The brightness enhancement sheet for a plasma display panel according to claim 1, wherein a refractive index of the pressure-sensitive adhesive layer is 1.4 or more and 1.7 or less. The said uneven surface has a semi-elliptical spherical concave part and / or a semi-elliptical spherical convex part whose ratio of the major axis length to the minor axis length is 1 or more and 3 or less. Brightness enhancement sheet for plasma display panels. The said uneven | corrugated surface has a semi-elliptical cylinder type concave surface part and / or a semi-elliptical cylinder type convex surface part whose ratio with respect to the minor axis length of a major axis length is 1 or more and 3 or less. Brightness enhancement sheet for plasma display panels. 3. The brightness enhancement sheet for a plasma display panel according to claim 1, wherein the light transmitting layer is formed by dispersing a large number of beads in a binder. 4. The brightness enhancement sheet for a plasma display panel according to claim 5, wherein the plurality of beads are made of beads completely embedded in the binder and / or beads partially embedded in the binder. 7. The brightness enhancement sheet for a plasma display panel according to claim 5, wherein a difference between a refractive index of the beads and a refractive index of the binder is 0.01 or more and 0.15 or less. A plasma display panel device using the brightness enhancement sheet for a plasma display panel according to claim 1.

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