Patent Application
20080144180
The present invention relates to a plasma display panel and a field emission display each having an anti-reflection function.
In various displays (a plasma display panel (hereinafter referred to as a POP), a field emission display (hereinafter referred to as an FED), and the like), there may be a case where it becomes hard to see images of a display screen due to reflection of its surroundings by surface reflection of incident light from external or the like, so that visibility is decreased. This is a considerable problem particularly when the size of the display device is increased or the display device is used outdoors.
In order to prevent such reflection of incident light from external, a method for providing an anti-reflection film for display screens of a PDP and an FED has been employed. For example, there is a method for providing an anti-reflection film that has a multilayer structure of stacked layers having different refractive indexes so as to be effective for a wide wavelength range of visible light (for example, Reference 1: Japanese Published Patent Application No. 2003-248102). With the multilayer structure, incident lights from external reflected at interfaces between the stacked layers interfere and cancel each other, which provides an anti-reflection effect.
Alternatively, as an anti-reflection structure, minute cone-shaped or pyramid-shaped projections are arranged over a substrate, so that reflectance on a surface of the substrate is decreased (for example, Reference 2: Japanese Published Patent Application No. 2004-85831).
However, with the above-described multilayer structure, light, which cannot be cancelled, of the incident lights from external reflected at the layer interfaces is emitted to a viewer side as reflected light. Further, in order to achieve mutual cancellation of incident lights from external, it is necessary to precisely control optical characteristics of materials, thicknesses, and the like of stacked films, and it has been difficult to perform anti-reflection treatment to all lights from external which are incident from various angles. In addition, the cone-shaped or pyramid-shaped anti-reflection structure does not have a sufficient anti-reflection function.
In view of the foregoing, a conventional anti-reflection film has a functional limitation, and a PDP and an FED each having a higher anti-reflection function have been demanded.
It is an object of the present invention to provide a highly-visible PDP and a highly-visible FED each having an anti-refection function capable of further reducing reflection of incident light from external.
The present invention provides a PDP and an FED each including an anti-reflection layer having a structure, in which a plurality of pyramid-shaped projections are arranged densely without a space therebetween, thereby changing a refractive index due to a physical shape that is the pyramid-shaped projections protruding toward the outside (air side) from a substrate surface to serve as a display screen. In the present invention, apexes of the plurality of pyramid-shaped projections are arranged at equal intervals, and each side of a base which forms a pyramid shape of a pyramid-shaped projection is arranged to be in contact with a side of a base which forms a pyramid shape of an adjacent pyramid-shaped projection. In other words, one pyramid-shaped projection is surrounded by other pyramid-shaped projections, and the base of the pyramid-shaped projection shares a side of a base with the base of the adjacent pyramid-shaped projection.
Thus, since the pyramid-shaped projections are arranged densely without a space, at equal intervals between the apexes thereof, a PDP and an FED of the present invention each have an excellent anti-reflection layer with which incident light from external can be efficiently scattered in many directions.
As for the anti-reflection layer according to the present invention, it is preferable that each of the intervals between the apexes of the plurality of pyramid-shaped projections be 350 nm or less and the height of each of the plurality of pyramid-shaped projections be 800 nm or more. Further, the fill rate (filling (occupying) percentage on the substrate surface to serve as a display screen) of bases of the plurality of pyramid-shaped projections per unit area on the substrate surface to serve as a display screen is preferably 80% or more, and more preferably 90% or more. The fill rate is a percentage of a formation region of a pyramid-shaped projection over the substrate surface to serve as a display screen. When the fill rate is 80% or more, the percentage of a plane portion where a pyramid-shaped projection is not formed on the substrate surface to serve as a display screen is 20% or less. In addition, it is preferable that the ratio of the height to the width of a base of a pyramid-shaped projection be 5 or more.
The present invention can provide a PDP and an FED each having an anti-reflection layer including a plurality of adjacent pyramid-shaped projections; accordingly, a high anti-reflection function can be provided.
As the PDP, a main body of a display panel having a discharge cell, and a display panel to which a flexible printed circuit (FPC) or a printed wiring board (PWB) having one or more of an IC, a resistor, a capacitor, an inductor, a transistor, and the like is attached, can be given. In addition, an optical filter having an electromagnetic field shielding function or a near-infrared ray shielding function may be included.
As the FED, a main body of a display panel having a light emitting cell, and a display panel to which a flexible printed circuit (FPC) or a printed wiring board (PWB) having one or more of an IC, a resistor, a capacitor, an inductor, a transistor, and the like is attached, can be given. In addition, an optical filter having an electromagnetic field shielding function or a near-infrared ray shielding function may be included.
The PDP and the FED of the present invention are each provided with an anti-reflection layer having a plurality of pyramid-shaped projections which are arranged without a space on a surface. Since a side of a pyramid-shaped projection is not planar (a surface parallel to a display screen), incident light from external is reflected to not a viewer side but another adjacent pyramid-shaped projection, or travels between the pyramid-shaped projections. In addition, the pyramid-shaped projection is a shape which enables dense arrangement without a space and is an optimum shape having the largest number of sides among such shapes and having a high anti-reflection function capable of scattering light in multi-directions efficiently. Part of incident light enters a pyramid-shaped projection, and then the other part of the light is incident on an adjacent pyramid-shaped projection as reflected light. In this manner, incident light from external reflected at an interface of a pyramid-shaped projection repeats incidence on adjacent pyramid-shaped projections.
In other words, the number of entries of light from external which is incident on the pyramid-shaped projections of the anti-reflection layer is increased; therefore, the amount of incident light from external entering the pyramid-shaped projections of the anti-reflection layer is increased. Thus, the amount of incident light from external reflected to a viewer side can be reduced, and the cause of a reduction in visibility such as reflection can be prevented.
Accordingly, a PUP and an FED each having higher image quality and higher performance can be manufactured.
In the accompanying drawings:
Embodiment modes of the present invention will be hereinafter described with reference to the drawings. It is easily understood by those skilled in the art that various changes may be made in forms and details without departing from the spirit and the scope of the invention. Therefore, the present invention should not be interpreted as being limited to the descriptions of the embodiment modes below. In addition, the same reference numerals are commonly given to the same components or components having a similar function throughout all the drawings for explaining the embodiment modes, and repetitive explanation thereof is omitted.
In Embodiment Mode 1, an anti-reflection layer provided for a PDP and an FED of the present invention will be described. Specifically, an example of an anti-reflection layer having an anti-reflection function capable of further reducing reflection of incident light from external on a surface of each of a PDP and an FED, and aimed at providing high visibility for the PDP and the FED will be described.
When an anti-reflection layer has a plane portion (surface parallel to the display screen) to incident light from external, the incident light is reflected to the viewer side. Therefore, when the plane portion is small, an anti-reflection function is high. In addition, in order to scatter incident light from external further, a surface of the anti-reflection layer preferably includes surfaces with a plurality of angles.
The anti-reflection layer according to the present invention has a structure in which a plurality of pyramid-shaped projections are geometrically and densely arranged without a space; thus, the refractive index varies due to a physical shape that is a pyramid-shaped projection protruding toward the outside (toward a side of air) from a side of a display screen surface, so that reflection of light is prevented. In this embodiment mode, apexes of the plurality of pyramid-shaped projections are arranged at equal intervals and each side of a base which forms a pyramid shape of a pyramid-shaped projection is arranged to be in contact with a side of a base which forms a pyramid shape of an adjacent pyramid-shaped projection. That is, one pyramid-shaped projection is surrounded by other pyramid-shaped projections, and the base of the pyramid-shaped projection shares a side of a base with the base of the adjacent pyramid-shaped projection.
Thus, since the pyramid-shaped projections are arranged densely without a space, at equal intervals between the apexes thereof, a PDP and an FED of the present invention has an excellent anti-reflection function with which incident light from external can be efficiently scattered in many directions.
Since the plurality of pyramid-shaped projections 451 of this embodiment mode are arranged at equal intervals between the adjacent apexes thereof, the cross sections of
Further, the plurality of pyramid-shaped projections preferably have as many sides with different angles to the bases thereof as possible because incident light are scattered in more directions. In this embodiment mode, a pyramid-shaped projection has six sides which are in contact with a base of the pyramid-shaped projection at six different angles. In addition, since a base of a pyramid-shaped projection shares a vertex with bases of other pyramid-shaped projections and the pyramid-shaped projection is surrounded by a plurality of sides, which are provided at a plurality of angles, of the pyramid-shaped projections, incident light is more easily reflected in many directions. Therefore, the more vertices the base of a pyramid-shaped projection has, the more easily an anti-reflection function thereof can be exerted, and thus the base of the pyramid-shaped projection in this embodiment mode has six vertices. The pyramid-shaped projection having a hexagonal base of this embodiment mode is a shape by which pyramid-shaped projections can be arranged densely without a space therebetween, and is an optimal shape having the largest number of sides among such shapes and having an excellent anti-reflection function with which incident light can be scattered efficiently in many directions.
Since the plurality of pyramid-shaped projections 451 of this embodiment mode are arranged so that apexes of the adjacent pyramid-shaped projections are spaced at equal intervals, cross sections of
In
Optical calculation results of Comparative Example 1, Comparative Example 2, and the pyramid-shaped projection having a hexagonal base and six sides (also referred to as Structure A) of this embodiment mode are shown below. An optical calculation simulator for an optical device, Diffract MOD (manufactured by Rsoft Design Group Inc.) is used in the calculation of this embodiment mode. Each reflectance is calculated by 3D optical calculation.
In
When the fill rate of bases of a plurality of pyramid-shaped projections per unit area on a surface of a display screen (that is, a substrate surface to serve as a display screen) is 80% or more, and preferably 90% or more, the percentage of light from external which is incident on a plane portion is reduced. Accordingly, incident light from external can be prevented from being reflected to a viewer side, which is preferable. The fill rate is a percentage of a formation region of the pyramid-shaped projection over the substrate surface to serve as a display screen. When the fill rate is 80% or more, the percentage of the plane portion where the pyramid-shaped projection is not formed on the substrate surface to serve as a display screen is 20% or less.
Further,
Similarly, the change of the reflectances of the models, in which the pyramid-shaped projections each having a hexagonal base and six sides according to this embodiment mode are arranged densely, in each wavelength is calculated in which the width a and the height b of the pyramid-shaped projection is changed.
Further,
As shown in
Since the interval between apexes of the plurality of pyramid-shaped projections is the same as the width of each of the plurality of pyramid-shaped projections, in consideration of the above, it is preferable that each interval between apexes of the plurality of pyramid-shaped projections be 350 nm or less (more preferably, equal to or more than 100 nm and equal to or less than 300 nm) and the heights of the plurality of pyramid-shaped projections be 800 nm or more (more preferably equal to or more than 1000 nm, and still more preferably equal to or more than 1600 nm and equal to or less than 2000 nm). In addition, in the pyramid-shaped projection, the ratio of the height to the width of the base is preferably 5 or more.
Although
A glass substrate, a quartz substrate, or the like can be used as a substrate on which the pyramid-shaped projections are provided (that is, a substrate to serve as a display screen). Alternatively, a flexible substrate may be used. The flexible substrate refers to a substrate which can be bent or curved. For example, in addition to a plastic substrate made of polyethylene terephthalate, polyether sulphone, polystyrene, polyethylene naphthalate, polycarbonate, polyimide, polyarylate, or the like, elastomer which is a high molecular material having a property of being plasticized at a high temperature so that it can be shaped similarly to plastic and having a property of being elastic like a rubber at a room temperature, can be given. Alternatively, a film (made of polypropylene polyester, vinyl, polyvinyl fluoride, vinyl chloride, or polyamide; a film with an inorganic thin layer formed by evaporation; or the like) can be used.
In addition, the pyramid-shaped projection can be formed of not a material with a uniform refractive index but a material whose refractive index changes from an apical portion of the pyramid-shaped projection to a side of a substrate to serve as a display screen. For example, in each of the plurality of pyramid-shaped projections, a portion closer to the apical portion of the pyramid-shaped projection can be formed of a material having a refractive index equivalent to that of the air, so that reflection of light from external which is incident on the pyramid-shaped projection from the air, at the surface of the pyramid-shaped projection can be further reduced. On the other hand, in each of the plurality of pyramid-shaped projections, a portion closer to the substrate to serve as a display screen can be formed of a material having a refractive index more equivalent to that of the substrate, so that reflection, at an interface between the pyramid-shaped projection and the substrate, of light which travels through the pyramid-shaped projection and is incident on the substrate can be further reduced. When a glass substrate is used as the substrate, since the refractive index of the air is lower than that of a glass substrate, the pyramid-shaped projection may have such a structure in which a portion closer to an apical portion of the pyramid-shaped projection is formed of a material having a lower refractive index, and a portion closer to a base of the pyramid-shaped projection is formed of a material having a higher refractive index. In other words, the pyramid-shaped projection may have such a structure in which the refractive index increases from the apical portion to the base of the pyramid-shaped projection.
A material used for forming the pyramid-shaped projection may be appropriately selected in accordance with a material of the substrate forming a display screen surface, such as silicon, nitrogen, fluorine, oxide, nitride, or fluoride. As the oxide, the following can be used: silicon oxide, boric acid, sodium oxide, magnesium oxide, aluminum oxide (alumina), potassium oxide, calcium oxide, diarsenic trioxide (arsenious oxide), strontium oxide, antimony oxide, barium oxide, indium tin oxide (ITO), zinc oxide, indium zinc oxide (IZO) in which indium oxide is mixed with zinc oxide, a conductive material in which indium oxide is mixed with silicon oxide, organic indium, organic tin, indium oxide containing tungsten oxide, indium zinc oxide containing tungsten oxide, indium oxide containing titanium oxide, indium tin oxide containing titanium oxide, or the like. As the nitride, aluminum nitride, silicon nitride, or the like can be used. As the fluoride, lithium fluoride, sodium fluoride, magnesium fluoride, calcium fluoride, lanthanum fluoride, or the like can be used. One or more kinds of the above-described silicon, nitrogen, fluorine, oxide, nitride, and fluoride may be included. A mixing ratio thereof may be appropriately set in accordance with a ratio of components (a composition ratio) of the substrate.
The pyramid-shaped projection can be formed in such a manner that a thin film is formed by a sputtering method, a vacuum evaporation method, a PVD (physical vapor deposition) method, or a CVD (chemical vapor deposition) method such as a low-pressure CVD (LPCVD) method or a plasma CVD method, and then etched into a desired shape. Alternatively, a droplet discharge method by which a pattern can be selectively formed, a printing method by which a pattern can be transferred or drawn (a method for forming a pattern such as screen printing or offset printing), a coating method such as a spin coating method, a dipping method, a dispenser method, a brush coating method, a spraying method, a flow coating method, or the like can be employed. Still alternatively, an imprint technique or a nanoimprint technique with which a nanoscale three-dimensional structure can be formed by a transfer technology can be employed. Imprinting and nanoimprinting are techniques with which a minute three-dimensional structure can be formed without using a photolithography process.
The anti-reflection function of the anti-reflection layer having the plurality of pyramid-shaped projections according to the present invention will be described with reference to
In this manner, the anti-reflection layer according to this embodiment mode includes a plurality of pyramid-shaped projections, and incident light from external is reflected to not a viewer side but another adjacent pyramid-shaped projection because a side of the pyramid-shaped projection is not parallel to a display screen. Alternatively, reflected light travels between adjacent pyramid-shaped projections. Part of incident light enters an adjacent pyramid-shaped projection, and the other part of the incident light is then incident on the other adjacent pyramid-shaped projection as reflected light. In this manner, incident light from external reflected at an interface of a pyramid-shaped projection repeats incidence on adjacent pyramid-shaped projections.
In other words, the number of entries of light from external which is incident on the pyramid-shaped projections of the anti-reflection layer is increased; therefore, the amount of incident light from external entering the anti-reflection layer is increased. Thus, the amount of incident light from external reflected to a viewer side is reduced, and the cause of a reduction in visibility such as reflection can be prevented.
The present invention can provide a PDP and an FED with high visibility, each of which has an anti-reflection layer having a plurality of adjacent pyramid-shaped projections on a surface and thus has a high anti-reflection function capable of reducing reflection of incident light from external. Accordingly, a PDP and an FED with higher image quality and higher performance can be manufactured.
In Embodiment Mode 2, a PDP having an anti-reflection function capable of further reducing reflection of incident light from external and having excellent visibility will be described. That is, a structure of a PDP which includes a pair of substrates, at least a pair of electrodes provided between the pair of substrates, a phosphor layer provided between the pair of electrodes, and an anti-reflection layer provided on an outer side of one substrate of the pair of substrates will be described in detail.
In this embodiment mode, a surface discharge PDP of alternating current discharge type (AC type) is shown.
Discharge cells of a display portion are arranged in matrix, and each discharge cell is provided at an intersection of a display electrode included in the front substrate 110 and a data electrode 122 included in the back substrate 120.
In the front substrate 110, a display electrode extended in a first direction is formed over one surface of a first light-transmitting substrate 111. The display electrode includes light-transmitting conductive layers 112a and 112b, a scan electrode 113a, and a sustain electrode 113b. In addition, a light-transmitting insulating layer 114 which covers the first light-transmitting substrate 111, the light-transmitting conductive layers 112a and 112b, the scan electrode 113a, and the sustain electrode 113b is formed. Further, a protective layer 115 is formed over the light-transmitting insulating layer 114.
An anti-reflection layer 100 is formed over the other surface of the first light-transmitting substrate 111. The anti-reflection layer 100 includes a pyramid-shaped projection 101. As the pyramid-shaped projection 101, the pyramid-shaped projection described in Embodiment Mode 1 can be used.
In the back substrate 120, a data electrode 122 extended in a second direction intersecting with the first direction is formed over one surface of a second light-transmitting substrate 121. A dielectric layer 123 which covers the second light-transmitting substrate 121 and the data electrode 122 is formed. Over the dielectric layer 123, partitions (ribs) 124 for separating discharge cells are formed. A phosphor layer 125 is formed in a region surrounded by the partitions (ribs) 124 and the dielectric layer 123.
A space surrounded by the phosphor layer 125 and the protective layer 115 is filled with a discharge gas.
A high strain point glass substrate, a soda lime glass substrate, or the like which can withstand a baking process with a temperature of more than 500° C. can be used for the first light-transmitting substrate 111 and the second light-transmitting substrate 121.
The light-transmitting conductive layers 112a and 112b formed over the first light-transmitting substrate 111 preferably have light-transmitting properties to transmit light emitted from a phosphor and are formed using ITO or tin oxide. In addition, the light-transmitting conductive layers 112a and 112b may be rectangular or T-shaped. The light-transmitting conductive layers 112a and 112b can be formed in such a way that a conductive layer is formed over the first light-transmitting substrate 111 by a sputtering method, a coating method, or the like and then selectively etched. Alternatively, the light-transmitting conductive layers 112a and 112b can be formed in such a way that a composition is selectively applied by a droplet discharge method, a printing method, or the like and baked. Further alternatively, the light-transmitting conductive layers 112a and 112b can be formed by a lift-off method.
The scan electrode 113a and the sustain electrode 113b are preferably formed using a conductive layer with a low resistance value and can be formed using chromium, copper, silver, aluminum, gold, or the like. In addition, a stack of copper, chromium, and copper or a stack of chromium, aluminum, and chromium can be used. As a method for forming the scan electrode 113a and the sustain electrode 113b, a similar method to the method for forming the light-transmitting conductive layers 112a and 112b can be used as appropriate.
The light-transmitting insulating layer 114 can be formed using low melting glass containing lead or zinc. As a method for forming the light-transmitting insulating layer 114, a printing method, a coating method, a green sheet laminating method, or the like can be used.
The protective layer 115 is provided to protect the dielectric layer from discharged plasma and promote secondary electron release. Therefore, a material having a low ion sputtering rate, a high secondary electron emission coefficient, a low voltage to generate discharged plasma, and a high surface insulating property is preferably used. A typical example of such a material is magnesium oxide. As a method for forming the protective layer 115, an electron beam evaporation method, a sputtering method, an ion plating method, an evaporation method, or the like can be used.
Note that a color filter and a black matrix may be provided at an interface between the first light-transmitting substrate 111 and the light-transmitting conductive layers 112a and 112b, at an interface between the light-transmitting conductive layers 112a and 112b and the light-transmitting insulating layer 114, in the light-transmitting insulating layer 114, at an interface between the light-transmitting insulating layer 114 and the protective layer 115, or the like. By providing a color filter and a black matrix, contrast between light and dark can be improved and a color purity of emission color of a phosphor can be improved. As a color filter, a colored layer corresponding to an emission spectrum of a light-emission cell is provided.
As a material of the color filter, there are a material in which an inorganic pigment is dispersed in light-transmitting glass having a low melting point, colored glass in which a metal or metal oxide is included as a colored component, and the like. As the inorganic pigment, an iron oxide based material (red), a chromium based material (green), a chromium-vanadium based material (green), a cobalt aluminate based material (blue), or a zirconium-vanadium based material (blue) can be used. As the inorganic pigment of the black matrix, a cobalt-chromium-iron based material can be used. Other than the inorganic pigment, pigments can be mixed as appropriate to be used for a desired color tone of RGB or a desired color tone of the black matrix.
The data electrode 122 can be formed in a similar manner to the scan electrode 113a and the sustain electrode 113b.
The dielectric layer 123 is preferably white with a high reflectance in order to efficiently take out light emitted by a phosphor to the front substrate side. The dielectric layer 123 can be formed using low melting glass containing lead, alumina, titania, or the like. As a method for forming the dielectric layer 123, a similar method to the method for forming the light-transmitting insulating layer 114 can be used as appropriate.
The partitions (ribs) 124 are formed using low melting glass containing lead and ceramic. The partitions (ribs) can prevent color mixture of emitted light between adjacent discharge cells and improve color purity when the partitions (ribs) each have a well curb shape. As a method for forming the partitions (ribs) 124, a screen printing method, a sandblast method, an additive method, a photosensitive paste method, a pressure casting method, or the like can be used. Although the partitions (ribs) 124 each have a well curb shape in
The phosphor layer 125 can be formed using various phosphor materials which can emit light by ultraviolet irradiation. For example, there are BaMgAl14O23:Eu as a phosphor material for blue, (Y.Ga)BO3:Eu as a phosphor material for red, and Zn2SiO4:Mn as a phosphor material for green; however, other phosphor materials can be used as appropriate. The phosphor layer 125 can be formed by a printing method, a dispenser method, an adhesive method using light, a phosphor dry film method in which a dry film resist including dispersed phosphor powder is laminated, or the like.
As the discharge gas, a mixed gas of neon and argon; a mixed gas of helium, neon, and xenon; a mixed gas of helium, xenon, and krypton; or the like can be used.
Next, a method for manufacturing a PDP is described hereinafter
At the periphery of the back substrate 120, glass for sealing is printed by a printing method and then pre-baked. Next, the front substrate 110 and the back substrate 120 are aligned, provisionally fixed, and then heated. Accordingly, the glass for sealing is melted and cooled, so that the front substrate 110 and the back substrate 120 are attached together to be made as a panel. Next, an inside of the panel is exhausted to a vacuum while the panel is heated. Then, after a discharge gas is introduced to the inside of the panel from a vent pipe provided for the back substrate 120, an open end portion of the vent pipe is closed and the inside of the panel is hermetically sealed by heating the vent pipe provided for the back substrate 120. Then, a cell of the panel discharges electricity, and aging in which discharging is continued until light-emission properties and discharge characteristics become stable is performed, so that the panel can be completed.
As shown in
When plasma is generated inside the PDP, electromagnetic waves, infrared rays, and the like are released to the outside of the PDP. The electromagnetic waves are harmful to human bodies. In addition, the infrared rays cause malfunction of a remote controller. Therefore, the optical filter 130 is preferably used for shielding electromagnetic waves and infrared rays.
The anti-reflection layer 100 may be formed over the light-transmitting substrate 131 by the manufacturing method described in Embodiment Mode 1. Alternatively, the anti-reflection layer 100 may exist in a surface part of the light-transmitting substrate 131. Further alternatively, the anti-reflection layer 100 may be attached to the light-transmitting substrate 131 with a UV hardening adhesive or the like.
As a typical example of the electromagnetic wave shield layer 133, there are metal mesh, metal fiber mesh, mesh in which an organic resin fiber is coated with a metal layer, and the like. The metal mesh and the metal fiber mesh are formed of gold, silver, platinum, palladium, copper, titanium, chromium, molybdenum, nickel, zirconium, or the like. The metal mesh can be formed by a plating method, an electroless plating method, or the like after a resist mask is formed over the light-transmitting substrate 131. Alternatively, the metal mesh can be formed in such a way that a conductive layer is formed over the light-transmitting substrate 131, and the conductive layer is selectively etched using a resist mask formed by a photolithography process. In addition, the metal mesh can be formed by appropriately using a printing method, a droplet discharge method, or the like. Note that each surface of the metal mesh, the metal fiber mesh, and the metal layer formed on a surface of a resin fiber is preferably processed to be black in order to reduce visible-light reflectance.
An organic resin fiber of which surface is covered with a metal layer can be formed of polyester, nylon, vinylidene chloride, aramid, vinylon, cellulose, or the like. In addition, the metal layer over the surface of the organic resin fiber can be formed using any of the materials for the metal mesh.
As the electromagnetic wave shield layer 133, a light-transmitting conductive layer having a surface resistance of 10Ω/□ or less, preferably 4Ω/□ or less, more preferably 2.5Ω/□ or less can be used. As the light-transmitting conductive layer, a light-transmitting conductive layer formed of ITO, tin oxide, zinc oxide, or the like can be used. The thickness of the light-transmitting conductive layer is preferably 100 nm or more and 5 μm or less in terms of surface resistance and light-transmitting properties.
In addition, as the electromagnetic wave shield layer 133, a light-transmitting conductive film can be used. As the light-transmitting conductive film, a plastic film in which conductive particles are dispersed can be used. As the conductive particles, there are particles or the like of carbon, gold, silver, platinum, palladium, copper, titanium, chromium, molybdenum, nickel, zirconium, and the like.
Further, as the electromagnetic wave shield layer 133, a plurality of electromagnetic wave absorbers 135 each having a pyramid shape as shown in
Note that the electromagnetic wave shield layer 133 may be attached to the near-infrared ray shielding layer 132 with an adhesive or the like such as an acrylic-based adhesive, a silicone-based adhesive, or a urethane-based adhesive.
Note that an end portion of the electromagnetic wave shield layer 133 is grounded to an earth terminal.
The near-infrared ray shielding layer 132 is a layer in which one or more kinds of dyes having the maximum absorption wavelength at a wavelength of 800 nm to 1000 nm is dissolved in an organic resin. As the dyes, there are a cyanine-based compound, a phthalocyanine-based compound, a naphthalocyanine-based compound, a naphthoquinone-based compound, an anthraquinone-based compound, a dithiol-based complex, and the like.
As the organic resin which can be used for the near-infrared ray shielding layer 132, a polyester resin, a polyurethane resin, an acrylic resin, or the like can be used as appropriate. In addition, a solvent can be used as appropriate to dissolve the dye.
As the near-infrared ray shielding layer 132, a light-transmitting conductive layer of a copper based material, a phthalocyanine based compound, zinc oxide, silver, ITO, or the like; or a nickel complex layer may be formed over the surface of the light-transmitting substrate 131. Note that in the case where the near-infrared ray shielding layer 132 is formed of the material, the near-infrared ray shielding layer 132 has light-transmitting properties and a thickness which blocks near-infrared rays.
As a method for forming the near-infrared ray shielding layer 132, a composition can be applied by a printing method, a coating method, or the like and hardened by heat or light irradiation.
As the light-transmitting substrate 131, a glass substrate, a quartz substrate, a flexible substrate, or the like can be used. The flexible substrate is a substrate capable of being bent, and for example, a plastic substrate formed of polyethylene terephthalate, polyethersulfone, polystyrene, polyethylene naphthalate, polycarbonate, polyimide, polyarylate, or the like; and the like are given. In addition, a film (formed of polypropylene, polyester, vinyl, polyvinyl fluoride, vinyl chloride, or polyamide; a film with an inorganic thin layer formed by evaporation; or the like) can be used.
Note that in
In particular, when plastic is used for the light-transmitting substrate 131 and the optical filter 130 is provided over the surface of the front substrate 110 using the adhesive 136, reduction in thickness and weight of a plasma display can be achieved.
Note that the electromagnetic wave shield layer 133 and the near-infrared ray shielding layer 132 are formed using different layers here; however, one functional layer having an electromagnetic wave shield function and a near-infrared ray shielding function may be formed for the electromagnetic wave shield layer 133 and the near-infrared ray shielding layer 132. In this way, the thickness of the optical filter 130 can be reduced, and reduction in weight and thickness of the PDP can be achieved.
Next, a PDP module and a driving method thereof are described with reference to
As shown in
A data electrode driver circuit 144 that drives a data electrode is provided over the second light-transmitting substrate which is part of the back substrate 120 and is connected to the data electrode. Here, the data electrode driver circuit 144 is provided over a wiring board 146 and connected to the data electrode through an FPC 147, Although not shown, a control circuit which controls the scan electrode driver circuit 142, the sustain electrode driver circuit 143, and the data electrode driver circuit 144 is provided for the first light-transmitting substrate 111 or the second light-transmitting substrate 121.
As shown in
Note that, since the sustain electrode 113b does not need to scan the inside of the display portion 145, the sustain electrode 113b can be used as a common electrode. In addition, by setting the sustain electrode as a common electrode, the number of driver ICs can be reduced.
In this embodiment mode, the reflection type surface discharge PDP of AC type is shown as a PDP; however, the present invention is not limited to this. In a transmissive discharge PDP of AC discharge type, the anti-reflection layer 100 can be provided. Further, also in a PDP of direct current (DC) discharge type, the anti-reflection layer 100 can be provided.
The PDP described in this embodiment mode includes the anti-reflection layer on its surface. The anti-reflection layer includes a plurality of pyramid-shaped projections, and incident light from external is reflected to not a viewer side but another adjacent pyramid-shaped projection because the interface of the pyramid-shaped projection is not perpendicular to an incident direction of the light from external. Alternatively, the reflected light travels between adjacent pyramid-shaped projections. Part of incident light enters an adjacent pyramid-shaped projection having a hexagonal base, and the other part of the incident light is then incident on the other adjacent pyramid-shaped projection as reflected light. In this manner, incident light from external reflected at an interface of a pyramid-shaped projection repeats incidence on adjacent pyramid-shaped projections.
In other words, the number of entries of light from external which is incident on the pyramid-shaped projections of a PDP is increased; therefore, the amount of incident light from external entering the pyramid-shaped projections is increased. Thus, the amount of incident light from external reflected to a viewer side is reduced, and the cause of a reduction in visibility such as reflection can be prevented.
In addition, by a structure, in which a plurality of pyramid-shaped projections are arranged densely without a space therebetween, a refractive index changes due to a physical shape that is the pyramid-shaped projections protruding toward the outside (air side) from a display screen surface. In this embodiment mode, apexes of the plurality of pyramid-shaped projections are arranged at equal intervals, and each side of a base which forms a pyramid shape of a pyramid-shaped projection is arranged to be in contact with a side of a base which forms a pyramid shape of an adjacent pyramid-shaped projection. In other words, one pyramid-shaped projection is surrounded by other pyramid-shaped projections, and the base of the pyramid-shaped projection shares a side of a base with the base of the adjacent pyramid-shaped projection.
Thus, since the pyramid-shaped projections are arranged densely without a space, at equal intervals between the apexes thereof, a PDP of the present invention has an excellent anti-reflection function with which incident light from external can be efficiently scattered in many directions.
In this embodiment mode, it is preferable that each of the intervals between the apexes of the plurality of pyramid-shaped projections and the width of the base of each of the plurality of pyramid-shaped projections be 350 nm or less each and the height of each of the plurality of pyramid-shaped projections be 800 nm or more. Further, the fill rate (filling (occupying) percentage on the substrate surface to serve as a display screen) of bases of the plurality of pyramid-shaped projections per unit area on the substrate surface to serve as a display screen is preferably 80% or more, and more preferably 90% or more. The fill rate is a percentage of a formation region of a pyramid-shaped projection over the substrate surface to serve as a display screen. When the fill rate is 80% or more, the percentage of a plane portion where a pyramid-shaped projection having a hexagonal base is not formed on the substrate surface to serve as a display screen is 20% or less. In addition, it is preferable that the ratio of the height to the width of a base of a pyramid-shaped projection be 5 or more. When the above-described conditions are satisfied, the percentage of incidence of light from external which is incident on the plane portion is reduced and thus reflection to a viewer side can be prevented.
Further, the plurality of pyramid-shaped projections preferably have as many sides with different angles to the bases thereof as possible because incident light are scattered in more directions. In this embodiment mode, a pyramid-shaped projection has six sides which are in contact with a base of the pyramid-shaped projection at six different angles. In addition, since a base of a pyramid-shaped projection shares a vertex with bases of other pyramid-shaped projections and the pyramid-shaped projection is surrounded by a plurality of sides, which are provided at a plurality of angles, of the pyramid-shaped projections, incident light is more easily reflected in many directions. Therefore, the more vertices the base of a pyramid-shaped projection has, the more easily an anti-reflection function thereof can be exerted, and thus the base of the pyramid-shaped projection in this embodiment mode has six vertices. The pyramid-shaped projection having a hexagonal base of this embodiment mode is a shape by which pyramid-shaped projections can be arranged densely without a space therebetween, and is an optimal shape having the largest number of sides among such shapes and having an excellent anti-reflection function with which incident light can be scattered efficiently in many directions.
The pyramid-shaped projection can be formed of not a material with a uniform refractive index but a material of which the refractive index changes from an apical portion of the pyramid-shaped projection to a side of a substrate to serve as a display screen. For example, in each of the plurality of pyramid-shaped projections, a portion closer to the apical portion of the pyramid-shaped projection can be formed of a material having a refractive index equivalent to that of air, so that reflection of light from external which is incident on the pyramid-shaped projection from the air, at the surface of the pyramid-shaped projection can be further reduced. On the other hand, in each of the plurality of pyramid-shaped projections each having a hexagonal base, a portion closer to the substrate to serve as a display screen can be formed of a material having a refractive index more equivalent to that of the substrate, so that reflection, at an interface between the pyramid-shaped projection and the substrate, of light which travels through the pyramid-shaped projection and is incident on the substrate can be reduced. When a glass substrate is used as the substrate, since the refractive index of the air is lower than that of the glass substrate, the pyramid-shaped projection may have such a structure in which a portion closer to an apical portion of the pyramid-shaped projection is formed of a material having a lower refractive index and a portion closer to a base of the pyramid-shaped projection is formed of a material having a higher refractive index. In other words, the pyramid-shaped projection may have such a structure in which the refractive index increases from the apical portion to the base of the pyramid-shaped projection.
By being provided with an anti-reflection layer having a plurality of adjacent pyramid-shaped projections on a surface, the PDP shown in this embodiment mode has a high anti-reflection function capable of reducing reflection of incident light from external. Therefore, a PDP with high visibility can be provided. Accordingly, a PDP with higher image quality and higher performance can be manufactured.
Embodiment Mode 3 will describe an FED having an anti-reflection function capable of reducing reflection of incident light from external and having excellent visibility. That is, a structure of an FED including a pair of substrates, a field emission element provided over one substrate of the pair of substrates, an electrode provided on the other substrate of the pair of substrates, a phosphor layer which is in contact with the electrode, and an anti-reflection layer provided on an outer side of the other substrate will be described in detail.
The FED is a display device in which phosphors are exited by an electron beam to emit light. The FED can be classified into a diode-type FED, a triode-type FED, and a tetrode-type FED according to the configurations of electrodes.
The diode-type FED has a structure where a rectangular cathode electrode is formed on a surface of a first substrate while a rectangular anode electrode is formed on a surface of a second substrate, and the cathode electrode and the anode electrode cross each other with a distance of several micrometers to several millimeters interposed therebetween. By setting the potential difference at an intersection in a vacuum space between the cathode electrode and the anode electrode at 10 kV or less, an electron beam is emitted between the electrodes. This electron reaches the phosphor layer which is provided for the cathode electrode to excite a phosphor, so that an image can be displayed by light emission.
The triode-type FED has a structure where a gate electrode is formed over a first substrate provided with a cathode electrode so that the gate electrode crosses the cathode electrode with an insulating film interposed therebetween. The cathode electrode and the gate electrode are arranged with a rectangular shape or in matrix, and an electron-emission element is formed at the intersection portion between the cathode electrode and the gate electrode, which includes the insulating film. By applying a voltage to the cathode electrode and the gate electrode, an electron beam can be emitted from the electron-emission element. This electron beam is pulled toward the anode electrode of the second substrate to which a voltage higher than the voltage to the gate electrode is applied, thereby exciting a phosphor in the phosphor layer provided for the anode electrode, so that an image can be displayed by light emission.
The tetrode-type FED has a structure where a plate-like or thin film converging electrode having an opening is formed in each pixel between the gate electrode and the anode electrode of the triode type-FED. By converging electron beams emitted from the electron-emission element by the converging electrode in each pixel, a phosphor in the phosphor layer provided for the anode electrode can be excited, and thus, an image can be displayed by light emission.
The discharge cells of a display portion are arranged in matrix.
In the front substrate 210, the phosphor layer 232 is formed over one surface of a first light-transmitting substrate 211. A metal back 234 is formed over the phosphor layer 232. Note that an anode electrode may be formed between the first light-transmitting substrate 211 and the phosphor layer 232. As the anode electrode, a rectangular conductive layer which extends in a first direction can be formed.
An anti-reflection layer 200 is formed over the other surface of the first light-transmitting substrate 211. The anti-reflection layer 200 includes a pyramid-shaped projection 201. As the pyramid-shaped projection 201, the pyramid-shaped projection described in Embodiment Mode 1 can be used.
In the back substrate 220, an electron-emission element 226 is formed over one surface of a second light-transmitting substrate 221. As the electron-emission element, various structures are proposed. Specifically, there are a Spindt-type electron-emission element, a surface-conduction electron-emission element, a ballistic-electron surface-emission electron-emission element, a MIM (metal-insulator-metal) element, a carbon nanotube, graphite nanofiber, diamond-like carbon (DLC), and the like.
Here, a typical electron-emission element is shown with reference to
A cathode electrode 222 and a cone-shaped electron source 225 formed over the cathode electrode 222 are included in a Spindt-type electron-emission element 230. The cone-shaped electron source 225 is formed of a metal or a semiconductor A gate electrode 224 is provided at the periphery of the cone-shaped electron source 225. Note that the gate electrode 224 and the cathode electrode 222 are insulated from each other by an interlayer insulating layer 223.
When a voltage is applied through the gate electrode 224 and the cathode electrode 222 formed in the back substrate 220, the electric field concentrates in an apical portion of the cone-shaped electron source 225 to produce an intense electric field, so that electrons are discharged into a vacuum from a metal or a semiconductor which forms the cone-shaped electron source 225 by tunneling. On the other hand, the front substrate 210 is provided with the metal back 234 (or anode electrode) and the phosphor layer 232. By applying a voltage to the metal back 234 (or anode electrode), an electron beam 235 emitted from the cone-shaped electron source 225 is guided to the phosphor layer 232, and a phosphor is exited, so that light emission can be obtained. Therefore, by arranging the cone-shaped electron sources 225 surrounded by the gate electrodes 224 in matrix and selectively applying a voltage to the cathode electrode, the metal back (or anode electrode), and the gate electrode, light emission of each cell can be controlled.
The Spindt-type electron-emission element has advantages in that electron extraction efficiency is high since an electron-emission element is provided in a central region of a gate electrode, which has the highest concentration of the electric field; in-plane uniformity of an extraction current is high since patterns having the arrangement of electron-emission elements can be accurately drawn to suitably arrange electric field distribution; and the like.
Next, a structure of a cell having the Spindt-type electron-emission element will be described. The front substrate 210 includes the first light-transmitting substrate 211, the phosphor layer 232 and a black matrix 233 formed over the first light-transmitting substrate 211, and the metal back 234 formed over the phosphor layer 232 and the black matrix 233.
As the first light-transmitting substrate 211, a substrate similar to the first light-transmitting substrate 111 described in Embodiment Mode 2 can be used.
For the phosphor layer 232, a phosphor material which is excited by the electron beam 235 can be used. Further, as the phosphor layer 232, phosphor layers of RGB can be provided in rectangular arrangement, lattice arrangement, or delta arrangement, so that color display is possible. Typically, Y2O2S:Eu (red), Zn2SiO4:Mn (green), ZnS:Ag, Al (blue), or the like can be used. Other than these, a phosphor material which is excited by a known electron beam can also be used.
The black matrix 233 is formed between the respective phosphor layers 232. By providing the black matrix, discrepancy in luminous color due to misalignment of an irradiated position of the electron beam 235 can be prevented. Further, by providing conductivity to the black matrix 233, the charge up of the phosphor layer 232 due to the electron beam 235 can be prevented. For the black matrix 233, carbon particles can be used. Alternatively, a known black matrix material for an FED can also be used.
The phosphor layer 232 and the black matrix 233 can be formed using a slurry process or a printing method. The slurry process is such a method that a composition in which the above-described phosphor material or carbon particles are mixed into a photosensitive material, a solvent, or the like is applied by spin coating and dried, and then exposed and developed.
The metal back 234 can be formed using a conductive thin film of aluminum or the like having a thickness of 10 to 200 nm, and preferably 50 to 150 nm. By providing the metal back 234, light which is emitted from the phosphor layer 232 and travels to the back substrate 220 side can be reflected toward the first light-transmitting substrate 211, so that luminance can be improved. In addition, damage to the phosphor layer 232 due to shock of ions generated by ionization of a gas which remains in a cell by the electron beam 235, can be prevented. Since the metal back 234 functions as an anode electrode with respect to the electron-emission element 230, the metal back 234 can guide the electron beam 235 to the phosphor layer 232. The metal back 234 can be formed in such a way that a conductive layer is formed by a sputtering method and then selectively etched.
The back substrate 220 includes the second light-transmitting substrate 221, the cathode electrode 222 formed over the second light-transmitting substrate 221, the cone-shaped electron sources 225 formed over the cathode electrode 222, the interlayer insulating layer 223 which separates the electron sources 225 into each cell, and the gate electrode 224 formed over the interlayer insulating layer 223.
As the second light-transmitting substrate 221, a substrate similar to the second light-transmitting substrate 121 described in Embodiment Mode 2 can be used.
The cathode electrode 222 can be formed using tungsten, molybdenum, niobium, tantalum, titanium, chromium, aluminum, copper, or ITO. As a method for forming the cathode electrode 222, an electron beam evaporation method, a thermal evaporation method, a printing method, a plating method, or the like can be used. Alternatively, the cathode electrode 222 can be formed in the following way: a conductive layer is formed by a sputtering method, a CVD method, an ion plating method, or the like over an entire surface, and then, the conductive layer is selectively etched by using a resist mask or the like. When an anode electrode is formed, the cathode electrode can be formed with a rectangular conductive layer which extends in a first direction parallel to the anode electrode.
The electron sources 225 can be formed of tungsten, a tungsten alloy, molybdenum, a molybdenum alloy, niobium, a niobium alloy, tantalum, a tantalum alloy, titanium, a titanium alloy, chromium, a chromium alloy, silicon which imparts n-type conductivity (doped with phosphorus), or the like.
The interlayer insulating layer 223 can be formed using an inorganic siloxane polymer including a Si—O—Si bond among compounds including silicon, oxygen, and hydrogen formed by using a siloxane polymer-based material as a starting material, which is typified by silica glass; or an organic siloxane polymer in which hydrogen bonded to silicon is substituted by an organic group such as methyl or phenyl, which is typified by an alkylsiloxane polymer, an alkylsilsesquioxane polymer, a silsesquioxane hydride polymer, or an alkylsilsesquioxane hydride polymer. When the interlayer insulating layer 223 is formed using the above material, a coating method, a printing method, or the like is used. Alternatively, as the interlayer insulating layer 223, a silicon oxide layer may be formed by a sputtering method, a CVD method, or the like. Note that the interlayer insulating layer 223 is provided with an opening in a region where the electron sources 225 are formed.
The gate electrode 224 can be formed using tungsten, molybdenum, niobium, tantalum, chromium, aluminum, copper, or the like. As a method for forming the gate electrode 224, the method for forming the cathode electrode 222 can be used as appropriate. The gate electrode 224 can be formed using a rectangular conductive layer which extends in a second direction that intersects with the first direction at 90°, Note that the gate electrode is provided with an opening in a region where the electron sources 225 are formed.
Note that in a space between the gate electrode 224 and the metal back 234, that is, in a space between the front substrate 210 and the back substrate 220, a converging electrode may be formed. The converging electrode is provided to converge an electron beam emitted from the electron-emission element. By providing the converging electrode, light emission luminance of a light-emission cell can be improved, reduction in contrast due to color mixture of adjacent cells can be suppressed, and so on. A more negative voltage compared with the metal back (or the anode electrode) is preferably applied to the converging electrode.
Next, a structure of a cell of an FED having a surface-conduction electron-emission element is described.
A surface-conduction electron-emission element 250 includes element electrodes 255 and 256 which are opposed to each other, and conductive layers 258 and 259 which are in contact with the element electrodes 255 and 256 respectively. The conductive layers 258 and 259 have a gap portion therebetween. When a voltage is applied to the element electrodes 255 and 256, an intense electric field is generated in the gap portion, and electrons are emitted from one of the conductive layers to the other thereof, due to a tunnel effect. By applying a positive voltage to the metal back 234 (or the anode electrode) formed in the front substrate 210, the electrons emitted from one of the conductive layers to the other thereof are guided to the phosphor layer 232. Then, this electron beam 260 excites a phosphor, thereby providing light emission.
Therefore, surface-conduction electron-emission elements are arranged in matrix, and a voltage is selectively applied to the element electrodes 255 and 256 and the metal back (or the anode electrode), so that light emission of each cell can be controlled.
Because a drive voltage of the surface-conduction electron-emission element is low compared with another electron-emission element, power consumption of the FED can be lowered.
Next, a structure of a cell having a surface-conduction electron-emission element is described. The front substrate 210 includes the first light-transmitting substrate 211, the phosphor layer 232 and the black matrix 233 formed over the first light-transmitting substrate 211, and the metal back 234 formed over the phosphor layer 232 and the black matrix 233. Note that an anode electrode may be formed between the first light-transmitting substrate 211 and the phosphor layer 232. As the anode electrode, a rectangular conductive layer which extends in a first direction can be formed.
The back substrate 220 includes the second light-transmitting substrate 221, a row direction wiring 252 formed over the second light-transmitting substrate 221, an interlayer insulating layer 253 formed over the row direction wiring 252 and the second light-transmitting substrate 221, a connection wiring 254 connected to the row direction wiring 252 with the interlayer insulating layer 253 interposed therebetween, the element electrode 255 which is connected to the connection wiring 254 and formed over the interlayer insulating layer 253, the element electrode 256 formed over the interlayer insulating layer 253, a column direction wiring 257 connected to the element electrode 256, the conductive layer 258 which is in contact with the element electrode 255, and the conductive layer 259 which is in contact with the element electrode 256. Note that the electron-emission element 250 shown in
The row direction wiring 252 can be formed using a metal such as titanium, nickel, gold, silver, copper, aluminum, or platinum; or an alloy thereof. As a method for forming the row direction wiring 252, a droplet discharge method, a vacuum evaporation method, a printing method, or the like can be used. Alternatively, the row direction wiring 252 can be formed in such a way that a conductive layer formed by a sputtering method, a CVD method, or the like is selectively etched. The thickness of each of the element electrodes 255 and 256 is preferably 20 nm to 500 nm.
As the interlayer insulating layer 253, a material and a formation method similar to those of the interlayer insulating layer 223 shown in
As the connection wiring 254, a material and a formation method similar to those of the row direction wiring 252 can be used as appropriate.
The pair of the element electrodes 255 and 256 can be formed using a metal such as chromium, copper, iridium, molybdenum, palladium, platinum, titanium, tantalum, tungsten, or zirconium; or an alloy thereof. As a method for forming the element electrodes 255 and 256, a droplet discharge method, a vacuum evaporation method, a printing method, or the like can be used. Alternatively, the element electrodes 255 and 256 can be formed in such a way that a conductive layer formed by a sputtering method, a CVD method, or the like is selectively etched. The thickness of each of the element electrodes 255 and 256 is preferably 20 nm to 500 nm.
As the column direction wiring 257, a material and a formation method similar to those of the row direction wiring 252 can be used as appropriate.
As materials of the pair of the conductive layers 258 and 259, a metal such as palladium, platinum, chromium, titanium, copper, tantalum, or tungsten; an oxide such as palladium oxide, tin oxide, or a mixture of indium oxide and antimony oxide; silicon; carbon; or the like can be used as appropriate. Further, a stack using a plurality of the above-described materials may be used. The conductive layers 258 and 259 can be formed using particles of any of the above-described materials. Note that an oxide layer may be formed at the peripheries of the particles of any of the above-described materials. By using the particles having an oxide layer, electrons can be accelerated and easily emitted. As a method for forming the conductive layers 258 and 259, a droplet discharge method, a vacuum evaporation method, a printing method, or the like can be used. The thickness of each of the conductive layers 258 and 259 is preferably 0.1 nm to 50 nm.
A distance of the gap portion formed between the pair of the conductive layers 258 and 259 is preferably 100 mm or less, and more preferably, 50 nm or less. The gap portion can be formed by cleavage due to application of a voltage to the conductive layers 258 and 259 or cleavage using a converged ion beam. Alternatively, the gap portion can be formed by selective etching using wet etching or dry etching with the use of a resist mask.
Note that a converging electrode may be formed between the front substrate 210 and the back substrate 220. By providing the converging electrode, an electron beam emitted from the electron-emission element can be converged; accordingly, light emission luminance of a cell can be improved, reduction in contrast due to color mixture of adjacent cells can be suppressed, or the like. A negative voltage compared with the metal back 234 (or the anode electrode) is preferably applied to the converging electrode.
Next, a method for manufacturing an FED panel is described hereinafter
At the periphery of the back substrate 220, glass for sealing is printed by a printing method and then pre-baked. Next, the front substrate 210 and the back substrate 220 are aligned, provisionally fixed, and then heated. Accordingly, the glass for sealing is melted and then cooled, so that the front substrate 210 and the back substrate 220 are attached together to be made as a panel. Next, an inside of the panel is exhausted into a vacuum while the panel is heated. Next, by heating a vent pipe provided for the back substrate 220, an open end portion of the vent pipe is closed and the inside of the panel is vacuum locked. Accordingly, an FED panel can be completed.
As shown in
Note that in
In particular, by using plastic for the light-transmitting substrate 131 and providing the optical filter 130 on the surface of the front substrate 210 using the adhesive 136, reduction in thickness and weight of an FED can be achieved.
Note that here, the structure in which the optical filter 130 includes the electromagnetic wave shield layer 133 and the anti-reflection layer 200 is described; however, a near-infrared ray shielding layer may be provided together with the electromagnetic wave shield layer 133 in a similar manner to Embodiment Mode 2. Further alternatively, one layer of a functional layer having an electromagnetic wave shield function and a near-infrared light shielding function may be formed.
Next, an FED module having a Spindt-type electron-emission element and a driving method thereof will be described with reference to
As shown in
A driver circuit 263 which applies a voltage to a metal back (or an anode electrode) is provided for the second light-transmitting substrate which is part of the back substrate 220 and is connected to the metal back (or the anode electrode). Here, the driver circuit 263 which applies a voltage to the metal back (or the anode electrode) is provided over a wiring board 264, and the driver circuit 263 and the metal back (or the anode electrode) are connected through an FPC 265. Further, although not shown, a control circuit which controls the driver circuits 261 to 263 is provided over the first light-transmitting substrate 211 or the second light-transmitting substrate 221.
As shown in
Next, an FED module having a surface-conduction electron-emission element and a driving method thereof will be described with reference to
As shown in
Over the second light-transmitting substrate which is part of the back substrate 220, the driver circuit 263 which applies a voltage to a metal back (or an anode electrode) is provided and connected to the metal back (or the anode electrode). Although not shown, a control circuit which controls the driver circuits 261 to 263 is provided over the first light-transmitting substrate or the second light-transmitting substrate.
As shown in
The FED described in this embodiment mode includes the anti-reflection layer on its surface. The anti-reflection layer includes a plurality of pyramid-shaped projections, and incident light from external is reflected to not a viewer side but another adjacent pyramid-shaped projection because the interface of the pyramid-shaped projection is not perpendicular to an incident direction of the light from external. Alternatively, reflected light travels between adjacent pyramid-shaped projections. Part of incident light enters an adjacent pyramid-shaped projection having a hexagonal base, and the other part of the incident light is then incident on the other adjacent pyramid-shaped projection as reflected light. In this manner, incident light from external reflected at an interface of a pyramid-shaped projection repeats incidence on adjacent pyramid-shaped projections.
In other words, the number of entries of light from external which is incident on the pyramid-shaped projections of an FED is increased; therefore, the amount of incident light from external entering the pyramid-shaped projections is increased. Thus, the amount of incident light from external reflected to a viewer side is reduced, and the cause of a reduction in visibility such as reflection can be prevented.
In the present invention, by a structure, in which a plurality of pyramid-shaped projections are arranged densely without a space therebetween, a refractive index changes due to a physical shape that is the pyramid-shaped projections protruding toward the outside (air side) from a display screen surface. In this embodiment mode, apexes of the plurality of pyramid-shaped projections are arranged at equal intervals, and each side of a base which forms a pyramid shape of a pyramid-shaped projection is arranged to be in contact with a side of a base which forms a pyramid shape of an adjacent pyramid-shaped projection. In other words, one pyramid-shaped projection is surrounded by other pyramid-shaped projections, and the base of the pyramid-shaped projection shares a side of a base with the base of the adjacent pyramid-shaped projection.
Thus, since the pyramid-shaped projections are arranged densely without a space, at equal intervals between the apexes thereof, an FED of the present invention has an excellent anti-reflection function with which incident light from external can be efficiently scattered in many directions.
In this embodiment mode, it is preferable that each of the intervals between the apexes of the plurality of pyramid-shaped projections and the width of the base of each of the plurality of pyramid-shaped projections be 350 nm or less each and the height of each of the plurality of pyramid-shaped projections be 800 nm or more. Further, the fill rate (filling (occupying) percentage on the substrate surface to serve as a display screen) of bases of the plurality of pyramid-shaped projections per unit area on the substrate surface to serve as a display screen is preferably 80% or more, and more preferably 90% or more. The fill rate is a percentage of a formation region of a pyramid-shaped projection over the substrate surface to serve as a display screen. When the fill rate is 80% or more, the percentage of a plane portion where a pyramid-shaped projection having a hexagonal base is not formed on the substrate surface to serve as a display screen is 20% or less. In addition, it is preferable that the ratio of the height to the width of a base of a pyramid-shaped projection be 5 or more. When the above-described conditions are satisfied, the percentage of incidence of light from external which is incident on the plane portion is reduced and thus reflection to a viewer side can be prevented.
Further, the plurality of pyramid-shaped projections preferably have as many sides with different angles to the bases thereof as possible because incident light are scattered in more directions. In this embodiment mode, a pyramid-shaped projection has six sides which are in contact with a base of the pyramid-shaped projection at six different angles. In addition, since a base of a pyramid-shaped projection shares a vertex with bases of other pyramid-shaped projections and the pyramid-shaped projection is surrounded by a plurality of sides, which are provided at a plurality of angles, of the pyramid-shaped projections, incident light is more easily reflected in many directions. Therefore, the more vertices the base of a pyramid-shaped projection has, the more easily an anti-reflection function thereof can be exerted, and thus the base of the pyramid-shaped projection in this embodiment mode has six vertices. The pyramid-shaped projection having a hexagonal base of this embodiment mode is a shape by which pyramid-shaped projections can be arranged densely without a space therebetween, and is an optimal shape having the largest number of sides among such shapes and having an excellent anti-reflection function with which incident light can be scattered efficiently in many directions.
The pyramid-shaped projection can be formed of not a material with a uniform refractive index but a material of which the refractive index changes from an apical portion of the pyramid-shaped projection to a side of a substrate to serve as a display screen. For example, in each of the plurality of pyramid-shaped projections, a portion closer to the apical portion of the pyramid-shaped projection can be formed of a material having a refractive index equivalent to that of air, so that reflection of light from external which is incident on the pyramid-shaped projection from the air, at the surface of the pyramid-shaped projection can be further reduced. On the other hand, in each of the plurality of pyramid-shaped projections each having a hexagonal base, a portion closer to the substrate to serve as a display screen can be formed of a material having a refractive index more equivalent to that of the substrate, so that reflection, at an interface between the pyramid-shaped projection and the substrate, of light which travels through the pyramid-shaped projection and is incident on the substrate can be reduced. When a glass substrate is used as the substrate, since the refractive index of the air is lower than that of the glass substrate, the pyramid-shaped projection may have such a structure in which a portion closer to an apical portion of the pyramid-shaped projection is formed of a material having a lower refractive index and a portion closer to a base of the pyramid-shaped projection is formed of a material having a higher refractive index. In other words, the pyramid-shaped projection may have such a structure in which the refractive index increases from the apical portion to the base of the pyramid-shaped projection.
By being provided with a plurality of adjacent pyramid-shaped projections on a surface, the FED shown in this embodiment mode has a high anti-reflection function capable of reducing reflection of incident light from external. Therefore, an FED with high visibility can be provided. Accordingly, an FED with higher image quality and higher performance can be manufactured.
With the PDP and FED of the present invention, a television device (also simply referred to as a television or a television receiver) can be completed.
A driver IC 2751 may be mounted on the substrate 2700 by a COG (chip on glass) method as shown in
As a structure of other external circuits in
An audio signal among signals received by the tuner 904 is sent to an audio signal amplifier circuit 909, and an output thereof is supplied to a speaker 913 through an audio signal processing circuit 910. A control circuit 911 receives control information of a receiving station (reception frequency) or sound volume from an input portion 912 and transmits signals to the tuner 904 and the audio signal processing circuit 910.
A television device can be completed by incorporating the display module into a chassis as shown in
A display panel 2002 is incorporated in a chassis 2001, and general TV broadcast can be received by a receiver 2005. When the display device is connected to a communication network by wired or wireless connections via a modem 2004, one-way (from a sender to a receiver) or two-way (between a sender and a receiver or between receivers) information communication can be performed. The television device can be operated by using a switch built in the chassis 2001 or a remote control unit 2006. A display portion 2007 for displaying output information may also be provided in the remote control device 2006.
Further, the television device may include a sub screen 2008 formed using a second display panel so as to display channels, volume, or the like, in addition to the main screen 2003.
Naturally, the present invention is not limited to the television device, and can be applied to various use applications as a large-sized display medium such as an information display board at a train station, an airport, or the like, or an advertisement display board on the street, as well as a monitor of a personal computer.
This embodiment mode can be appropriately combined with any of Embodiment Mode 1 to 3.
Examples of electronic devices using a PDP and an FED in accordance with the present invention are as follows: a television device (also simply referred to as a television or a television receiver), a camera such as a digital camera or a digital video camera, a cellular telephone device (also simply referred to as a cellular phone or a cell-phone), a portable information terminal such as a PDA, a portable game machine, a computer monitor, a computer, a sound reproducing device such as a car audio system, an image reproducing device including a recording medium such as a home-use game machine, and the like. In addition, the present invention can be applied to any gaming machine having a display device, such as a pachinko machine, a slot machine, a pinball machine, or a large-sized game machine. Specific examples of them are described with reference to
A portable information terminal device shown in
A digital video camera shown in
A cellular phone shown in
A portable television device shown in
A portable computer shown in
A slot machine shown in
As described above, a high-performance electronic device which can display a high-quality image with high visibility can be provided by using the display device of the present invention.
This embodiment mode can be appropriately combined with any of Embodiment Modes 1 to 4.
This application is based on Japanese Patent Application serial no. 2006-328025 filed with Japan Patent Office on Dec. 5, 2006, the entire contents of which are hereby incorporated by reference.
100: anti-reflection layer, 101: pyramid-shaped projection, 110: front substrate, 111: light-transmitting substrate, 114: light-transmitting insulating layer, 115: protective layer, 116: plasma, 117; ultraviolet ray, 118: light emission, 120: back substrate, 121: light-transmitting substrate, 122: data electrode, 123: dielectric layer, 124: partition (rib), 125: phosphor layer, 130: optical filter, 131; light-transmitting substrate, 132: near-infrared ray shielding layer, 133: electromagnetic wave shield layer, 134: gap, 135: electromagnetic wave absorber, 136: adhesive, 141: glass for scaling, 142: scan electrode driver circuit, 143: sustain electrode driver circuit, 144: data electrode driver circuit, 145: display portion, 146: wiring board, 147: FPC, 150: discharge cell, 200: anti-reflection layer, 201: pyramid-shaped projection, 210: front substrate, 211: light-transmitting substrate, 213: spacer, 220: back substrate, 221: light-transmitting substrate, 222: cathode electrode, 223: interlayer insulating layer, 224: gate electrode, 225: electron source, 226: electron-emission element, 230: electron-emission element, 232: phosphor layer, 233: black matrix, 234: metal back, 235: electron beam, 250: electron-emission element, 252: row direction wiring, 253: interlayer insulating layer, 254: connection wiring, 255: element electrode, 256: element electrode, 257: column direction wiring, 258: conductive layer, 259: conductive layer, 260: electron beam, 261: driver circuit, 262: driver circuit, 263: driver circuit, 264: wiring board, 265: FPC, 266: display portion, 267: light-emission cell, 410: substrate, 450: substrate, 451: pyramid-shaped projection, 470: substrate, 471: pyramid-shaped projection, 480: substrate, 481: pyramid-shaped projection, 486: film, 490: substrate, 491: pyramid-shaped projection, 904: tuner, 905: video signal amplifier circuit, 906: video signal processing circuit, 907: control circuit, 908: signal dividing circuit, 909: audio signal amplifier circuit, 910: audio signal processing circuit, 911: control circuit 912: input portion, 913: speaker, 112a: light-transmitting conductive layer, 113a: scan electrode, 113b: sustain electrode, 2001: chassis, 2002: display panel, 2003: main screen, 2004: modem, 2005: receiver, 2006: remote control unit, 2007: display portion, 2008: sub screen, 2009: speaker portion, 2010: chassis, 2011: display portion, 2012: remote control device, 2013: speaker portion, 2700: substrate, 2701: pixel portion, 2702: pixel, 2703: input terminal, 2750: PC (flexible printed circuit), 2751: driver IC, 411a: pyramid-shaped projection, 411b: pyramid-shaped projection, 411c: pyramid-shaped projection, 412a: incident light ray, 412b: reflected light ray, 412c: reflected light ray, 412d: reflected light ray, 413a: transmitted light ray, 413b: transmitted light ray, 413c: transmitted light ray, 413d: transmitted light ray, 5000: pyramid-shaped projection having a hexagonal base, 5100: apex, 5200: cone-shaped projection, 5230: pyramid-shaped projection having a square base, 5250: pyramid-shaped projection having a triangle base, 5300: pyramid-shaped projection having a hexagonal base, 5301: pyramid-shaped projection having a hexagonal base, 9101: main body, 9102: display portion, 9201: main body, 9202; display portion, 9301: main body, 9302: display portion, 9401: main body, 9402: display portion, 9501: main body, 9502: display portion, 9701: display portion, 9702: display portion, 5001a: pyramid-shaped projection, 5101a: apex, 5201a: cone-shaped projection, 5231a: pyramid-shaped projection, and 5251a: pyramid-shaped projection.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2006-328025 | Dec 2006 | JP | national |
