EP1691585A1 - Lichtemittierende einrichtung - Google Patents

Lichtemittierende einrichtung Download PDF

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Publication number
EP1691585A1
EP1691585A1 EP04792763A EP04792763A EP1691585A1 EP 1691585 A1 EP1691585 A1 EP 1691585A1 EP 04792763 A EP04792763 A EP 04792763A EP 04792763 A EP04792763 A EP 04792763A EP 1691585 A1 EP1691585 A1 EP 1691585A1
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EP
European Patent Office
Prior art keywords
light
emitting
layer
emitting element
electrode
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Withdrawn
Application number
EP04792763A
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English (en)
French (fr)
Inventor
Iwao c/o Matsushita Electric Industrial Co.L UENO
Junichi c/o Matsushita Electric Industrial C KATO
Seiji c/o Matsushita Electric Industria NISHIYAMA
Naoki c/o Matsushita Electric Industrial Co NODA
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Panasonic Corp
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Matsushita Electric Industrial Co Ltd
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Filing date
Publication date
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Publication of EP1691585A1 publication Critical patent/EP1691585A1/de
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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J61/00—Gas-discharge or vapour-discharge lamps
    • H01J61/02—Details
    • H01J61/38—Devices for influencing the colour or wavelength of the light
    • H—ELECTRICITY
    • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05B—ELECTRIC HEATING; ELECTRIC LIGHT SOURCES NOT OTHERWISE PROVIDED FOR; CIRCUIT ARRANGEMENTS FOR ELECTRIC LIGHT SOURCES, IN GENERAL
    • H05B33/00—Electroluminescent light sources
    • H05B33/12—Light sources with substantially two-dimensional radiating surfaces
    • H05B33/14—Light sources with substantially two-dimensional radiating surfaces characterised by the chemical or physical composition or the arrangement of the electroluminescent material, or by the simultaneous addition of the electroluminescent material in or onto the light source
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J31/00—Cathode ray tubes; Electron beam tubes
    • H01J31/08—Cathode ray tubes; Electron beam tubes having a screen on or from which an image or pattern is formed, picked up, converted, or stored
    • H01J31/10—Image or pattern display tubes, i.e. having electrical input and optical output; Flying-spot tubes for scanning purposes
    • H01J31/12—Image or pattern display tubes, i.e. having electrical input and optical output; Flying-spot tubes for scanning purposes with luminescent screen
    • H01J31/123—Flat display tubes
    • H01J31/125—Flat display tubes provided with control means permitting the electron beam to reach selected parts of the screen, e.g. digital selection
    • H01J31/127—Flat display tubes provided with control means permitting the electron beam to reach selected parts of the screen, e.g. digital selection using large area or array sources, i.e. essentially a source for each pixel group
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J61/00—Gas-discharge or vapour-discharge lamps
    • H01J61/02—Details
    • H01J61/12—Selection of substances for gas fillings; Specified operating pressure or temperature
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J61/00—Gas-discharge or vapour-discharge lamps
    • H01J61/70—Lamps with low-pressure unconstricted discharge having a cold pressure < 400 Torr
    • H01J61/76—Lamps with low-pressure unconstricted discharge having a cold pressure < 400 Torr having a filling of permanent gas or gases only
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J63/00—Cathode-ray or electron-stream lamps
    • H01J63/02—Details, e.g. electrode, gas filling, shape of vessel
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J63/00—Cathode-ray or electron-stream lamps
    • H01J63/06—Lamps with luminescent screen excited by the ray or stream
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J65/00—Lamps without any electrode inside the vessel; Lamps with at least one main electrode outside the vessel
    • H01J65/04—Lamps in which a gas filling is excited to luminesce by an external electromagnetic field or by external corpuscular radiation, e.g. for indicating plasma display panels
    • H01J65/042—Lamps in which a gas filling is excited to luminesce by an external electromagnetic field or by external corpuscular radiation, e.g. for indicating plasma display panels by an external electromagnetic field
    • H01J65/046—Lamps in which a gas filling is excited to luminesce by an external electromagnetic field or by external corpuscular radiation, e.g. for indicating plasma display panels by an external electromagnetic field the field being produced by using capacitive means around the vessel

Definitions

  • the present invention relates to a light-emitting element.
  • the invention relates to a light-emitting element as a constituent of a unit pixel of a large-screen display that is configured and manufactured easily and achieves low power consumption.
  • ELD electroluminescence display
  • FED field emission display
  • Non-patent document 1 an ELD has a basic structure in which an electric field is applied to a phosphor serving as a light-emitting layer via an insulating layer, and is classified into a distribution type and a thin film type.
  • the former has a structure in which particles of ZnS to which impurities such as Cu are added are distributed in an organic binder, which is then sandwiched between upper and lower electrodes via an insulating layer.
  • the impurities form a pn junction in the phosphor particles.
  • an electric field is applied, electrons emitted by a high electric field generated on the junction surface are accelerated, and then are recombined with positive holes, resulting in light emission.
  • the latter has a structure in which an electrode is provided at a phosphor thin film of Mn doped ZnS or the like serving as a light-emitting layer via an insulating layer. The presence of the insulating layer allows a high electric field to be applied to the light-emitting layer, and emitted electrons accelerated by the electric field excite the luminescence center, resulting in light emission.
  • a FED has a structure in which an electron-emitting element and a phosphor opposed thereto are contained in a vacuum vessel. Electrons emitted from the electron-emitting element in vacuum are accelerated and irradiated to the phosphor layer, whereby light is emitted.
  • Non-patent document 2 proposes the following as shown in FIG. 20.
  • a PZT ceramic 31 having a flat electrode 32 on one surface and a lattice electrode 33 on the other surface is provided in a vacuum vessel 36 so as to be opposed to a platinum electrode 34 with a grid electrode 35 interposed therebetween.
  • Reference numeral 37 denotes an air outlet. This proposal describes that the pressure in the vessel is 1.33 Pa (10 -2 Torr), and that no discharge occurs under atmospheric pressure.
  • Patent documents 1 and 2 also describe the technique for allowing a light-emitting layer to emit light by accelerating electrons emitted by polarization reversal of a ferroelectric in a vacuum vessel, or a display using this light emission technique.
  • a basic configuration thereof is as follows: an electrode having a phosphor layer is provided instead of the platinum electrode in Non-patent document 2, thereby allowing the phosphor layer to emit light.
  • Patent document 3 discloses an electric light emitting surface light source element as an example of a light-emitting element achieved by using electrons emitted by polarization reversal of a ferroelectric in non-vacuum.
  • this element includes a lower electrode 42, a ferroelectric thin film 41, an upper electrode 43, a carrier intensifying layer 48, a light-emitting layer 44, and a transparent electrode 46, which are formed on a substrate 45 in this order.
  • the upper electrode has an opening portion 47.
  • the carrier intensifying layer is formed of a semiconductor that is relatively low in dielectric constant and has a band gap that does not allow light of a wavelength emitted from the light-emitting layer to be absorbed. This element can be regarded as a kind of ELD.
  • Patent document 4 discloses a configuration in which a light-emitting layer made of a phosphor formed by sputtering is sandwiched between insulating layers, to which a pulse electric field is applied.
  • the insulator on one side of the light-emitting layer is formed of a ferroelectric thin film.
  • Plasma displays need no vacuum vessel.
  • a plasma display utilizes light emission caused by converting discharge energy into ultraviolet light energy once, so that the ultraviolet light excites phosphors.
  • a large amount of the ultraviolet light is absorbed by members other than the phosphors. For this reason, it is difficult to increase the luminous efficiency, and a large amount of power will be consumed by a large-screen plasma display.
  • EL displays need no vacuum vessel.
  • an inorganic EL display has a problem in luminous efficiency and color reproduction, and an organic EL display requires large-scale facilities for a thin film formation process for manufacturing a liquid crystal display and the like. Further, it is difficult to realize a large-screen EL display, and thus no such display is yet commercially available.
  • a light-emitting element of the present invention includes a light-emitting layer including a phosphor, and at least two electrodes.
  • the light-emitting element includes at least two kinds of electrically insulating layers with different dielectric constants, one of the electrically insulating layers is the light-emitting layer, and one of the two electrodes is formed in contact with one of the insulating layers.
  • the light emission principle of the present invention is as follows. That is, dielectric breakdown is caused between at least two electrodes to generate primary electrons (e-).
  • the primary electrons (e-) collide with phosphor particles of a light-emitting layer to cause surface discharge, and a large number of secondary electrons (e-) are generated.
  • Electrons and ultraviolet rays generated thereby in an avalanche manner collide with the luminescence center of the phosphor, so that the phosphor particles are excited to emit light.
  • a light-emitting element of the present invention includes, from a back surface side, at least a first electrode, a dielectric layer, a porous light-emitting layer, and a second electrode, and has a gap between the porous light-emitting layer and the electrode. Therefore, when an AC electric field is applied between the first electrode and the second electrode, gas breakdown is caused in the gap to accelerate the generation of primary electrons. By the primary electrons, surface discharge occurs in the porous light-emitting layer between the electrodes, so that secondary electrons and ultraviolet rays are emitted. The emitted secondary electrons and ultraviolet rays excite the luminescence center of the porous light-emitting layer, so that the porous light-emitting layer emits light.
  • the gap may be provided to have an arbitrary width, but the width is preferably in a range of not less than 1 ⁇ m to not more than 300 ⁇ m. When the width is less than 1 ⁇ m, it tends to be difficult to control the gap. When the width is more than 300 ⁇ m, dielectric breakdown is less likely to occur. In general, it is necessary to apply an electric field of 300 V or more (at intervals of 100 ⁇ m) at 3 kV/mm to cause dielectric breakdown of air in the atmosphere. Under a reduced pressure, although dielectric breakdown occurs at 300 V or less, the application of a high voltage causes damage to various parts of a cell structure.
  • the width of the gap is preferably in the above-mentioned range. More preferably, the width of the gap is in a range of not less than 10 ⁇ m to not more than 100 ⁇ m.
  • the light-emitting element of the present invention emits light by surface discharge in the porous light-emitting layer. There is no need to use a thin film formation process, a vacuum system, a carrier intensifying layer, and the like for forming the porous light-emitting layer. Therefore, the light-emitting element has a simple structure and is manufactured easily. Further, the light-emitting element exhibits favorable luminous efficiency and is to be driven with relatively low power consumption when being applied to a large-screen display. Further, in the light-emitting element of the present invention, discharge separation means may be provided between the porous light-emitting layers, whereby crosstalk during light emission can be avoided. Crosstalk herein refers to a phenomenon in which light emission from a pixel interacts with that from adjacent pixels to deteriorate the luminous efficiency.
  • the discharge separation means of the present invention is formed in particular of a partition wall and/or a space or the like.
  • the partition wall for separating the porous light-emitting layers is preferably an electrical insulator with a thickness of 80 to 300 ⁇ m.
  • a partition wall it preferably is made of an inorganic material.
  • an inorganic material glass, ceramic, a dielectric, or the like can be used.
  • a dielectric Y 2 O 3 , Li 2 O, MgO, CaO, BaO, SrO, Al 2 O 3 , SiO 2 , MgTiO 3 , CaTiO 3 , BaTiO 3 , SrTiO 3 , ZrO 2 , TiO 2 , B 2 O 3 , PbTiO 3 , PbZrO 3 , PbZrTiO 3 (PZT), or the like may be used.
  • the space preferably has a width of 80 to 300 ⁇ m.
  • the gap between the porous light-emitting layer and the second electrode may be partitioned by a rib in a thickness direction.
  • a preferable material of the rib may be selected from the materials for the partition wall. It is preferable that the rib and the partition wall have a surface that is as smooth as possible. A smooth surface facilitates hopping of generated electrons on the rib, resulting in increased luminous efficiency of the porous light-emitting layer.
  • an atmosphere in the light-emitting element is at least one selected from atmospheric air, oxygen, nitrogen, and a rare gas.
  • the light-emitting element is in an atmosphere under a reduced pressure including at least one selected from the above-mentioned gases.
  • the porous light-emitting layer emits light of at least red (R), green (G), or blue (B).
  • the porous light-emitting layer is formed of a phosphor particle with an insulating layer on its surface.
  • the porous light-emitting layer is formed of a phosphor particle and an insulative fiber.
  • the porous light-emitting layer is formed of a phosphor particle with an insulating layer on its surface and an insulative fiber.
  • the porous light-emitting layer has an apparent porosity in a range of not less than 10% to less than 100%.
  • an apparent porosity in a range of not less than 10% to less than 100%.
  • the first or second electrode is an address electrode or a display electrode.
  • the second electrode is a transparent electrode arranged on an observation side.
  • the light-emitting element of the present invention includes a dielectric layer, a porous light-emitting layer, a pair of electrodes, and another electrode.
  • the porous light-emitting layer includes an inorganic phosphor particle, a pair of the electrodes are arranged so that an electric field is applied to at least a part of the dielectric layer, and the other electrode is arranged so that an electric field is applied to at least a part of the porous light-emitting layer between the other electrode and at least one of a pair of the electrodes.
  • this light-emitting element is a multi-terminal light-emitting element such as a three-terminal light-emitting element, for example.
  • a pair of the electrodes may be arranged on the dielectric layer.
  • One of a pair of the electrodes may be arranged at a boundary between the dielectric layer and the porous light-emitting layer, and the other may be arranged on the dielectric layer. Further, the other electrode may be arranged on the porous light-emitting layer.
  • a pair of the electrodes may be formed so as to sandwich the boundary between the dielectric layer and the porous light-emitting layer therebetween.
  • a pair of the electrodes may be both formed at the boundary between the dielectric layer and the porous light-emitting layer.
  • One of a pair of the electrodes may be formed at the boundary between the dielectric layer and the porous light-emitting layer, and the other may be formed on the dielectric layer.
  • the porous light-emitting layer may be formed of a fine pore connected to a surface of the porous light-emitting layer, a gas filled in the fine pore, and a phosphor particle.
  • the gas filled in the fine pore can be at least one gas selected from at least one of atmospheric air, oxygen, nitrogen, and an inert gas, and a gas under a reduced pressure.
  • the dielectric layer may be formed of a sintered dielectric.
  • the dielectric layer may be formed of a dielectric particle and a binder.
  • the dielectric layer may be formed of a thin film.
  • the porous light-emitting layer may be formed of a phosphor particle and an insulating layer on a surface of the phosphor particle.
  • the porous light-emitting layer may be formed of a phosphor particle and an insulative fiber.
  • the porous light-emitting layer may be formed of a phosphor particle, an insulating layer on a surface of the phosphor particle, and an insulative fiber.
  • the porous light-emitting layer may emit light in at least one gas atmosphere selected from an atmosphere of atmospheric air, oxygen, nitrogen, and an inert gas, and a gas atmosphere under a reduced pressure. It is also preferable that an alternating electric field is applied between the other electrode and at least one electrode of a pair of the electrodes after the application of an electric field between a pair of the electrodes for polarization reversal.
  • the light-emitting element of the present invention includes a porous light-emitting body.
  • the porous light-emitting body includes an insulative phosphor particle, and a predetermined electric field or higher is applied to the porous light-emitting body, so that electric charge transfer is carried out.
  • the light-emitting element of the present invention includes an electron-emitting body, a porous light-emitting body, and a pair of electrodes.
  • the porous light-emitting body includes an inorganic phosphor particle and is arranged adjacent to the electron-emitting body so as to be irradiated with electrons generated from the electron-emitting body, and a pair of the electrodes are arranged so that an electric field is applied to at least a part of the porous light-emitting body.
  • a light-emitting element is formed of an assembly of a plurality of porous light-emitting layers, each having a dielectric layer and a first electrode on one surface and a second electrode on the other surface where the dielectric layer and the first electrode are not formed, and includes discharge separation means between the plurality of porous light-emitting layers.
  • the dielectric layer is shared by part of the plurality of porous light-emitting layers, and the discharge separation means is formed of a partition wall.
  • FIG. 1 is a cross-sectional view of the light-emitting element of the present embodiment.
  • FIGs. 2 to 6 are views for explaining manufacturing processes of the light-emitting element of the present embodiment.
  • reference numeral 1 denotes a light-emitting element
  • 2 denotes a porous light-emitting layer
  • 3 denotes a phosphor particle
  • 4 denotes an insulating layer
  • 5 denotes a substrate
  • 6 denotes a first electrode (back side electrode)
  • 7 denotes a second electrode (observation side electrode)
  • 8 denotes a transparent substrate
  • 9 denotes a gap (gas layer)
  • 10 denotes a dielectric layer
  • 11 denotes a partition wall.
  • an Ag paste is baked to a thickness of 30 ⁇ m to form the first electrode 6 into a predetermined shape. Then, as shown in FIG. 3, the dielectric layer with the electrode shown in FIG. 2 is adhered onto the substrate 5 made of glass or ceramic.
  • BaTiO 3 is used as the dielectric.
  • SrTiO 3 , CaTiO 3 , MgTiO 3 , PZT(PbZrTiO 3 ), PbTiO 3 , or the like also may be used as the dielectric to achieve the same effect.
  • Al 2 O 3 , MgO, ZrO 2 , or the like also may be used as the dielectric to achieve the same effect. In this case, however, the luminescence decreases as compared with the above-mentioned dielectrics having a higher relative dielectric constant. This can be improved by reducing the thickness of the dielectric layer.
  • the dielectric layer may be formed by a molecule deposition method such as sputtering, CVD, and deposition or with a thin film formation process such as a sol-gel process.
  • a molecule deposition method such as sputtering, CVD, and deposition
  • a thin film formation process such as a sol-gel process.
  • the dielectric layer is formed of a sintered body, this can be used also as the substrate 5.
  • the thickness of the dielectric layer varies considerably depending on how the dielectric layer is formed, e.g., the case where a sintered body is used or the case where a thick film process is used. Practically, however, the thickness is adjusted relative to the dielectric constant since a certain capacitance property is required.
  • the plurality of porous light-emitting layers 2 are formed on the dielectric layer 10 into a predetermined shape by screen printing.
  • the phosphor particles 3, each being coated with the insulating layer 4 made of a metal oxide such as MgO, are prepared for the porous light-emitting layer 2 as follows.
  • an inorganic compound such as BaMgAl 10 O 17 :Eu 2+ (blue), Zn 2 SiO 4 :Mn 2+ (green), and YBO 3 :Eu 3+ (red), with an average particle diameter of 2 to 3 ⁇ m can be used.
  • the insulating layer 4 of MgO is formed on a surface of each phosphor particle in a common manner. Specifically, the phosphor particle 3 is added to an Mg precursor complex solution, stirred for a long time, and then taken out from the solution, followed by drying.
  • the phosphor particle 3 is subjected to heat treatment at 400°C to 600°C in the atmosphere, whereby a uniform coating layer of MgO, i.e., the insulating layer 4, is formed on the surface of the phosphor particle 3.
  • a kneaded paste containing 45 mass% of terpineol ( ⁇ -terpineol) and 5 mass% of ethyl cellulose with respect to 50 mass% of the phosphor particle coated with the insulating layer 4 is prepared for each phosphor.
  • the porous light-emitting layer 2 is screen-printed into a predetermined shape by using this paste, followed by drying. This operation is repeated a plurality of times, so that the thickness of the printed porous light-emitting layer is adjusted to be 80 to 100 ⁇ m.
  • the porous light-emitting layers in order for the porous light-emitting layers to emit red (R), green (G), and blue (B) light, respectively, the porous light-emitting layers, in general, are formed so as to be arranged regularly by being printed in order in a predetermined pattern (e.g., a strip shape) for the respective luminescent colors.
  • a predetermined pattern e.g., a strip shape
  • the substrate 5 on which the porous light-emitting layers are printed as described above is placed finally in an N 2 atmosphere, and subjected to heat treatment at 400°C to 600°C for 2 to 5 hours, whereby the assembly of the porous light-emitting layers 2 with a thickness of about 50 to 80 ⁇ m is formed.
  • the paste is obtained by adding the organic binder and the organic solvent to the phosphor particle.
  • the same effect is achieved by using a paste obtained by adding a colloidal silica solution to the phosphor particle.
  • FIG. 6 is an enlarged schematic cross-sectional view of the porous light-emitting layer 2 of the present embodiment.
  • the figure shows a state in which the phosphor particles 3, each being coated uniformly with the insulating layer 4 of MgO, are in contact with each other as a result of being subjected to the heat treatment to form the porous light-emitting layer.
  • the porosity of the porous light-emitting layer is increased.
  • the apparent porosity is in a range of not less than 10% to less than 100%. It is not preferable that the porosity is increased extremely to 100%, so that pores are opened widely, because such a porous light-emitting layer causes a decrease in luminous efficiency and air discharge to occur therein.
  • the porosity is less than 10%, the generation of surface discharge is inhibited. (Surface discharge occurs at an interface between gas (in this case, an air gap) and an insulator solid (phosphor particle).
  • the apparent porosity is decreased, the air gaps disappear, resulting in difficulty in generating surface discharge.
  • the apparent porosity when the apparent porosity is increased, the air gaps become larger than a mean free path of electrons as mentioned above, resulting in difficulty in generating surface discharge.
  • the apparent porosity is in a range of not less than 10% to less than 100%, it is assumed that the phosphor particles are in approximate point contact so as to be adjacent three-dimensionally to each other.
  • the partition wall 11 with a thickness of about 80 to 300 ⁇ m is formed as shown in FIG. 5.
  • the partition wall 11 may be formed in advance. Further, the partition wall 11 may be formed of a glass paste or a resin containing ceramic particles.
  • a kneaded paste containing 50 mass% of ⁇ -terpineol with respect to 50 mass% of mixed particles of ceramic and glass (1 : 1 by weight) is screen-printed in a predetermined pattern, followed by drying. This operation is repeated so that the thickness of the printed paste is adjusted to be about 100 to 350 ⁇ m.
  • the thus-obtained assembly is subjected to heat treatment at 400°C to 600°C for 2 to 5 hours in an N 2 atmosphere, whereby the partition wall 11 with a thickness of about 80 to 300 ⁇ m can be formed.
  • the partition wall is formed of a thermosetting resin, such as an epoxy resin, a phenol resin, and a cyanate resin. One of these resins is screen-printed in the air gap between the porous light-emitting layers to form the partition wall.
  • the assembly of the porous light-emitting layers is covered entirely with the transparent substrate 8 such as a glass plate on which the second electrode 7 made of ITO (indium-tin oxide alloy) is formed beforehand so as to be opposed to the porous light-emitting layer, whereby the light-emitting element 1 of the present embodiment as shown in FIG. 1 is obtained.
  • the transparent substrate 8 is attached to the partition wall 11 by using colloidal silica, water glass, a resin, or the like, so that the slight gap is provided between the porous light-emitting layer 2 and the second electrode 7.
  • the gap 9 between the porous light-emitting layer 2 and the second electrode 7 preferably has a vertical width in a range of 30 to 250 ⁇ m, and in particular in a range of 40 to 220 ⁇ m. When the width is beyond this range, a high voltage is required to be applied for the generation of primary electrons due to gas breakdown, which is not preferable for the reasons of economical efficiency and reliability.
  • the width of the gap may be smaller than the above range, it is desirable that the gap has such a width as to prevent the porous light-emitting layer from being in contact with the second electrode so as to allow the porous light-emitting layer to emit light uniformly and thoroughly.
  • a transparent substrate on which copper wiring is provided can be used.
  • Copper wiring is formed in a microporous mesh shape and has an open area ratio (ratio of a portion where no wiring is provided to the entire substrate) of 90%, and accordingly this substrate allows light to pass therethrough approximately as favorably as the transparent substrate with the ITO film. Further, copper is favorable since it has a much lower resistance than ITO and greatly contributes to increased luminous efficiency.
  • gold, silver, platinum, or aluminum can be used instead of copper. However, in the case of using copper and aluminum that are likely to be oxidized, a treatment for providing resistance to oxidization is necessary.
  • the light-emitting element that is formed of an assembly of the plurality of porous light-emitting layers, each having the dielectric layer and the first electrode on one surface and the second electrode on the other surface where the dielectric layer and the first electrode are not formed, and includes the discharge separation means between the plurality of porous light-emitting layers.
  • the partition wall is formed as the discharge separation means between the plurality of porous light-emitting layers
  • the dielectric layer is formed on part of the plurality of porous light-emitting layers so that the dielectric layer is shared by the part of the plurality of porous light-emitting layers.
  • the phosphor particle 3 is coated with the insulating layer 4 of MgO. Since MgO has a high specific resistance (10 9 ⁇ •cm or more), surface discharge can occur efficiently. An insulating layer with a low specific resistance is not preferable since surface discharge is less likely to occur, and a short circuit may occur in some cases. For these reasons, it is desirable to coat the phosphor particle with an insulating metal oxide with a high specific resistance. It should be appreciated that when the phosphor particle itself to be used has a high specific resistance, surface discharge occurs easily without the coating of an insulating metal oxide.
  • the insulating layer at least one selected from Y 2 O 3 , Li 2 O, CaO, BaO, SrO, Al 2 O 3 , SiO 2 , and ZrO 2 can be used as well as MgO.
  • These oxides are stable substances with an extremely low standard free energy of formation ⁇ G f0 (e.g., - 100 kcal/mol or less at room temperature).
  • the insulating layer of these substances is favorable since it has a high specific resistance and allows discharge to occur easily, and is less likely to be reduced.
  • this layer also serves as an excellent protective coating for suppressing reduction and deterioration due to ultraviolet rays of the phosphor particle during discharge, resulting in increased durability of the phosphor.
  • the insulating layer can be formed by chemisorption or physical adsorption using a CVD method, a sputtering method, a deposition method, a laser method, a shearing stress method, and the like. It is desirable for the insulating layer to be homogeneous and uniform so as not to be peeled off. To this end, it is important, in forming the insulating layer, to immerse the phosphor particle in a weak acid solution of acetic acid, oxalic acid, citric acid, or the like so as to wash impurities attached to a surface of the phosphor particle.
  • the phosphor particle is subjected to a pretreatment in a nitrogen atmosphere at 200°C to 500°C for about 1 to 5 hours before the formation of the insulating layer.
  • the reason for this is as follows.
  • a usual phosphor particle contains a large amount of adsorbed water and water of crystallization, and the formation of the insulating layer on the phosphor particle in such a state exerts an undesirable effect on the lifetime property, such as a deterioration in brightness and a shift in emission spectrum.
  • the phosphor particle is washed with a weak acid solution, it is rinsed thoroughly in water before performing the pretreatment.
  • the points to note during the heat treatment process for forming the porous light-emitting layer include heat treatment temperature and atmosphere.
  • the heat treatment is performed in a nitrogen atmosphere at a temperature in a range of 450°C to 1200°C, a valence of the doped rare earth element in the phosphor is not changed.
  • the treatment is performed at temperatures higher than this temperature range, however, the valence of the doped rare earth element may be changed or a solid solution of the insulating layer and the phosphor may be formed, and therefore care should be taken to avoid this.
  • the optimum heat treatment temperature is preferably in a range of 450°C to 1200°C.
  • the heat treatment atmosphere it is preferable to perform the heat treatment in a nitrogen atmosphere so as to avoid an effect on the valence of the doped rare earth element in the phosphor particle.
  • the thickness of the insulating layer is set to about 0.1 to 2.0 ⁇ m.
  • the thickness may be determined in view of an average particle diameter of the phosphor particle and efficiency of surface discharge occurrence.
  • the phosphor with an average particle diameter on a submicron order has a relatively thin coating.
  • a large thickness of the insulating layer is not preferable since it may result in a shift in emission spectrum, a deterioration in brightness, and the like.
  • an AC electric field is applied between the first electrode 6 and the second electrode 7.
  • the dielectric layer 10, the porous light-emitting layer 2, and the gap (gas layer) 9 are present in series in a thickness direction between the electrodes 6 and 7.
  • the applied electric field is focused on the gap 9 in inverse proportion to the capacitance of each of the portions.
  • gas breakdown is caused in the gap 9, and primary electrons (e-) 24 shown in FIG. 17 are generated.
  • the primary electrons (e-) collide with the phosphor particles 3 and the insulating layers 4 of the porous light-emitting layer 2 to cause surface discharge, and a large number of secondary electrons (e ⁇ ) 25 are generated.
  • polarization reversal is performed repeatedly in the dielectric layer. Accordingly, electrons are generated, and as a result of electric charge being injected into the porous light-emitting layer, surface discharge occurs. Surface discharge occurs continuously during the application of an electric field. Electrons and ultraviolet rays generated in an avalanche manner during the application of an electric field collide with the luminescence center of the phosphors, so that the phosphor particles 3 are excited to emit light.
  • an electric field (frequency: 1 kHz) of about 0.72 to 1.5 kV/mm is applied in a thickness direction of the porous light-emitting layer to allow the phosphor particles 3 to emit light.
  • an alternating electric field (frequency: 1 kHz) of about 0.5 to 1.0 kV/mm is applied, so that surface discharge occurs continuously to sustain the light emission of the phosphor particles 3.
  • a current value during discharge is 0.1 mA or less. It was confirmed that light emission once started was sustained even when the voltage was decreased to about 50% to 80% of the voltage applied initially, and that a high brightness, a high contrast, a high recognition capability, and a high reliability were ensured in light emission of each of the three colors.
  • the light-emitting element is driven in the atmosphere. However, it was confirmed that even in an atmosphere of oxygen, nitrogen, and an inert gas or in a gas atmosphere under a reduced pressure, the light-emitting element emitted light similarly.
  • the light-emitting element of the present embodiment emits light by surface discharge in the porous light-emitting layer.
  • the light-emitting element unlike a conventional light-emitting element, there is no need to use a thin film formation process for manufacturing the light-emitting element, and neither a vacuum system nor a carrier intensifying layer is necessary. Therefore, the light-emitting element has a simple structure and is manufactured and processed easily. Further, it is possible to provide a light-emitting element that exhibits favorable luminous efficiency and is to be driven with relatively low power consumption when being applied to a large-screen display.
  • the partition wall is provided as the discharge separation means at a boundary between the porous light-emitting layers, whereby crosstalk during light emission can be avoided in a relatively simple manner.
  • a light-emitting element is formed of an assembly of a plurality of porous light-emitting layers, each having a dielectric layer and a first electrode on one surface and a second electrode on the other surface where the dielectric layer and the first electrode are not formed, and includes discharge separation means between the plurality of porous light-emitting layers.
  • the discharge separation means is formed of a partition wall.
  • FIG. 7 is a cross-sectional view of the light-emitting element of the present embodiment.
  • Reference numeral 1 denotes a light-emitting element
  • 2 denotes a porous light-emitting layer
  • 3 denotes a phosphor particle
  • 4 denotes an insulating layer
  • 5 denotes a substrate
  • 6 denotes a first electrode (back side electrode)
  • 7 denotes a second electrode (observation side electrode)
  • 8 denotes a transparent substrate
  • 9 denotes a gap (gas layer)
  • 10 denotes a dielectric layer
  • 11 denotes a partition wall.
  • the dielectric layer 10 and the first electrode 6 formed under the porous light-emitting layers are shared by the plurality of porous light-emitting layers.
  • the dielectric layer and the first electrode may be formed with respect to each of the plurality of porous light-emitting layers.
  • the light-emitting element of the present embodiment has such a configuration, and a cross section thereof is shown in FIG. 7.
  • the light-emitting element of the present embodiment can be manufactured in the same manner as in Embodiment 1. Practically, an Ag paste is baked initially to form the first electrode 6 at a place where the porous light-emitting layer is to be formed in a predetermined pattern and to be arranged. On the first electrode 6, the dielectric layer is formed by a thick film process or the like, and then the porous light-emitting layer is formed by screen printing. After that, as in Embodiment 1, the partition wall is formed, and finally the transparent substrate 8 with the second electrode is arranged, whereby the light-emitting element of the present embodiment as shown in FIG. 7 can be manufactured.
  • an electric field of about 0.72 to 1.5 kV/mm is applied in a thickness direction of the porous light-emitting layer to allow the phosphor particles 3 to emit light. Thereafter, an alternating electric field of about 0.5 to 1.0 kV/mm is applied, so that surface discharge occurs continuously to sustain the light emission of the phosphor particles 3.
  • an electric field of about 0.72 to 1.5 kV/mm is applied in a thickness direction of the porous light-emitting layer to allow the phosphor particles 3 to emit light.
  • an alternating electric field of about 0.5 to 1.0 kV/mm is applied, so that surface discharge occurs continuously to sustain the light emission of the phosphor particles 3.
  • a current value during discharge is 0.1 mA or less. It was confirmed that light emission once started was sustained even when the voltage was decreased to about 50% to 80% of the voltage applied initially, and that a high brightness, a high contrast, a high recognition capability, and a high reliability were ensured in light emission of each of the three colors.
  • the light-emitting element is driven in the atmosphere. However, it was confirmed that even in an atmosphere of oxygen, nitrogen, and an inert gas or in a gas atmosphere under a reduced pressure, the light-emitting element emitted light similarly.
  • the light-emitting element of the present embodiment emits light by surface discharge in the porous light-emitting layer.
  • the light-emitting element unlike a conventional light-emitting element, there is no need to use a thin film formation process for manufacturing the light-emitting element, and neither a vacuum system nor a carrier intensifying layer is necessary. Therefore, the light-emitting element has a simple structure and is manufactured and processed easily. Further, it is possible to provide a light-emitting layer that exhibits favorable luminous efficiency and is to be driven with relatively low power consumption when being applied to a large-screen display.
  • the partition wall is provided as the discharge separation means at a boundary between the porous light-emitting layers, whereby crosstalk during light emission can be avoided in a relatively simple manner.
  • a description will be given of a light-emitting element that is formed of an assembly of a plurality of porous light-emitting layers, each having a dielectric layer and a first electrode on one surface and a second electrode on the other surface where the dielectric layer and the first electrode are not formed, and includes discharge separation means between the plurality of porous light-emitting layers.
  • the discharge separation means is formed of a conductive partition wall.
  • FIG. 8 is a cross-sectional view of the light-emitting element of the present embodiment.
  • reference numeral 1 denotes a light-emitting element
  • 2 denotes a porous light-emitting layer
  • 3 denotes a phosphor particle
  • 4 denotes an insulating layer
  • 5 denotes a substrate
  • 6 denotes a first electrode (back side electrode)
  • 7 denotes a second electrode (observation side electrode)
  • 8 denotes a transparent substrate
  • 9 denotes a gap (gas layer)
  • 10 denotes a dielectric layer
  • 11 denotes a partition wall.
  • the conductive partition wall 11 that has a static-shielding effect and is effective in extending surface discharge is used as the discharge separation means.
  • a conductive partition wall can be formed of a deposited metal of various kinds. A description will be given of a method for forming the conductive partition wall by using electroless nickel plating, for example.
  • the light-emitting element is manufactured specifically as follows. Initially, on a surface of the substrate 5 made of ceramic, a resist film is screen-printed at places other than a place where the partition wall is to be formed. Then, the substrate 5 is immersed in a solution of tin chloride and palladium chloride. This treatment is referred to as a catalyzing/sensitizing treatment, and the treatment including its pre-treatment and after-treatment can be performed easily with a commercially available treatment agent.
  • the ceramic substrate 5 treated in this manner is immersed in a solution (pH 4 to 6) containing nickel sulfite and sodium hypophosphite as main components, and is subjected to a treatment at about 90°C so that metal nickel is deposited to a thickness of 80 to 300 ⁇ m, whereby the partition wall 11 with a predetermined shape can be formed on the surface of the substrate 5. In this manner, the ceramic substrate 5 on which the conductive partition wall 1 is formed can be obtained.
  • an Ag paste is baked on the substrate 5 to form the first electrode 6.
  • the first electrode 6 is formed slightly apart from the conductive partition wall 11 so as to be kept from contact therewith.
  • the dielectric layer 10 is formed on the first electrode 6 by a thick film process or the like.
  • a paste containing phosphor particles 3, each being coated uniformly with the insulating layer 4 is screen-printed, followed by firing, whereby the porous light-emitting layer 2 is formed in a predetermined pattern.
  • an assembly of the porous light-emitting layers is covered entirely with the transparent substrate 8 made of glass on which an ITO film is provided as the second electrode 7, resulting in the light-emitting element 1 as shown in FIG. 8.
  • the second electrode of ITO is spaced slightly apart from the conductive partition wall so as to be kept from contact therewith, whereby the application of a voltage for driving the light-emitting element is not hindered.
  • the light-emitting element that is formed of an assembly of the plurality of porous light-emitting layers, each having the dielectric layer and the first electrode on one surface and the second electrode on the other surface where the dielectric layer and the first electrode are not formed, and includes the discharge separation means between the plurality of porous light-emitting layers.
  • the discharge separation means is formed of the conductive partition wall.
  • the conductive partition wall is formed as in the present embodiment, surface discharge occurs easily, which contributes to a decrease in the driving voltage. More specifically, an electric field of about 0.58 to 1.2 kV/mm is applied in a thickness direction of the porous light-emitting layer to allow the phosphor particles 3 to emit light. Thereafter, an alternating electric field of about 0.4 to 0.8 kV/mm is applied, so that surface discharge occurs continuously to sustain the light emission of the phosphor particles 3. When a higher electric field is applied, the generation of electrons and ultraviolet rays is accelerated, and when a lower electric field is applied, the generation thereof is insufficient.
  • a current value during discharge is 0.1 mA or less. It was confirmed that light emission once started was sustained even when the voltage was decreased to about 50% to 80% of the voltage applied initially, and that a high brightness, a high contrast, a high recognition capability, and a high reliability were ensured in light emission of each of the three colors.
  • the light-emitting layer of the present embodiment emits light by surface discharge in the porous light-emitting layer.
  • the light-emitting element unlike a conventional light-emitting element, there is no need to use a thin film formation process for manufacturing the light-emitting element, and neither a vacuum system nor a carrier intensifying layer is necessary. Therefore, the light-emitting element has a simple structure and is manufactured and processed easily. Further, it is possible to provide a light-emitting layer that exhibits favorable luminous efficiency and is to be driven with relatively low power consumption when being applied to a large-screen display.
  • the partition wall is provided as the discharge separation means at a boundary between the porous light-emitting layers, whereby crosstalk during light emission can be avoided in a relatively simple manner.
  • a description will be given of a light-emitting element that is formed of an assembly of a plurality of porous light-emitting layers, each having a dielectric layer and a first electrode on one surface and a second electrode on the other surface where the dielectric layer and the first electrode are not formed, and includes discharge separation means between the plurality of porous light-emitting layers.
  • the plurality of porous light-emitting layers are arranged so as to share the second electrode, and the discharge separation means is formed of a gap.
  • FIG. 9 is a cross-sectional view of the light-emitting element of the present embodiment
  • FIGs. 10 to 13 are views for explaining manufacturing processes of the light-emitting element of the present embodiment.
  • reference numeral 1 denotes a light-emitting element
  • 2 denotes a porous light-emitting layer
  • 3 denotes a phosphor particle
  • 4 denotes an insulating layer
  • 5 denotes a substrate
  • 6 denotes a first electrode (back side electrode)
  • 7 denotes a second electrode (observation side electrode)
  • 8 denotes a transparent substrate
  • 9 denotes a gap (gas layer)
  • 10 denotes a dielectric layer
  • 12 denotes a space for separating the porous light-emitting layers
  • 15 denotes a side wall.
  • an Ag paste is baked on one side of the substrate 5 made of glass or ceramic to form the first electrode 6 into a predetermined shape. Then, as shown in FIG.11, the dielectric layer 10 is formed on the first electrode 6 by a thick film process or the like.
  • the porous light-emitting layer 2 is formed into a predetermined shape on the dielectric layer 10.
  • the phosphor particles 3, each being coated with the insulating layer 4 made of a metal oxide such as MgO, are used as in Embodiment 1.
  • an inorganic compound such as BaMgAl 10 O 17 :Eu 2+ (blue), Zn 2 SiO 4 :Mn 2+ (green), and YBO 3 :Eu 3+ (red), with an average particle diameter of 2 to 3 ⁇ m can be used.
  • a kneaded paste containing 45 mass% of ⁇ -terpineol and 5 mass% of ethyl cellulose with respect to 50 mass% of the phosphor particle coated with the insulating layer 4 is prepared for each phosphor.
  • This paste is screen-printed on the dielectric layer 10, followed by drying. This operation is repeated a plurality of times, so that the thickness of the printed paste is adjusted to be 80 to 100 ⁇ m.
  • the substrate 5 on which the porous light emitting layer is printed in the above-mentioned manner is subjected to heat treatment at 400°C to 600°C for 2 to 5 hours in an N 2 atmosphere.
  • heat treatment at 400°C to 600°C for 2 to 5 hours in an N 2 atmosphere.
  • an assembly of the porous light-emitting layers 2 with a thickness of about 50 to 80 ⁇ m is formed on the substrate.
  • the space 12 of about 80 to 300 ⁇ m is left, instead of providing a partition wall, at a boundary in the assembly of the porous light-emitting layers, and functions as an alternative to the partition wall.
  • the side wall 15 is formed so as to surround the entire assembly of the porous light-emitting layers, thereby supporting the transparent substrate 8 as described later.
  • the side wall 15 is formed by screen-printing of a glass paste, followed by drying. This operation is performed a plurality of times, and then the thus-obtained substrate is fired at 600°C. As a result, as shown in FIG. 13, the side wall 15 with a thickness of about 80 to 300 ⁇ m is formed.
  • the side wall 15 may be formed of a glass paste or a resin containing ceramic particles. Specifically, in the former case, a kneaded paste containing 50 mass% of ⁇ -terpineol with respect to 50 mass% of mixed particles of ceramic and glass (1 : 1 by weight) is screen-printed, followed by drying. This operation is repeated so that the thickness of the printed paste is adjusted to be about 100 to 350 ⁇ m. Then, the thus-obtained substrate is subjected to heat treatment at 400°C to 600°C for 2 to 5 hours in an N 2 atmosphere, whereby the side wall 15 with a thickness of about 80 to 300 ⁇ m can be formed.
  • the partition wall is formed of a thermosetting resin, such as an epoxy resin, a phenol resin, and a cyanate resin.
  • a thermosetting resin such as an epoxy resin, a phenol resin, and a cyanate resin.
  • One of these resins is selected and printed so as to surround the entire assembly of the porous light-emitting layers.
  • the transparent substrate 8 such as a glass plate on which the second electrode 7 made of ITO (indium-tin oxide alloy) is formed is adhered to the side wall 15 so as to cover the assembly of the porous light-emitting layers entirely, whereby the light-emitting element 1 in the present embodiment as shown in FIG. 9 is obtained.
  • the second electrode 7 is formed in a stripe shape, for example, so as to be opposed to the porous light-emitting layer, and is shared by the plurality of porous light-emitting layers.
  • the slight gap is provided between the porous light-emitting layer 2 and the second electrode 7, and the width of the gap is preferably in a range of 30 to 250 ⁇ m, and in particular in a range of 40 to 220 ⁇ m.
  • a substrate on which mesh-shaped fine wiring made of copper, gold, silver, platinum, aluminum, or the like is patterned can be used.
  • the light-emitting element that is formed of an assembly of the plurality of porous light-emitting layers, each having a dielectric layer and the first electrode on one surface and the second electrode on the other surface where the dielectric layer and the first electrode are not formed, and includes the discharge separation means between the plurality of porous light-emitting layers.
  • the second electrode is arranged so as to be shared by the plurality of porous light-emitting layers, and the discharge separation means is formed of the space.
  • this light-emitting element 1 In order to drive the light-emitting element 1 as shown in FIG. 9, an AC electric field is applied between the first electrode 6 and the second electrode 7. By the application of an AC electric field, gas breakdown is caused in the gap 9, and accordingly electrons are generated. As a result of electric charge being injected into the porous light-emitting layer, surface discharge occurs. Surface discharge occurs continuously during the application of an electric field. Electrons and ultraviolet rays generated in an avalanche manner during the application of an electric field collide with the luminescence center of the phosphors, so that the phosphor particles 3 are excited to emit light.
  • an electric field of about 0.85 to 1.8 kV/mm is applied in a thickness direction of the porous light-emitting layer to allow the phosphor particles 3 to emit light. Thereafter, an alternating electric field of about 0.6 to 1.2 kV/mm is applied, so that surface discharge occurs continuously to sustain the light emission of the phosphor particles 3.
  • an electric field of about 0.85 to 1.8 kV/mm is applied in a thickness direction of the porous light-emitting layer to allow the phosphor particles 3 to emit light.
  • an alternating electric field of about 0.6 to 1.2 kV/mm is applied, so that surface discharge occurs continuously to sustain the light emission of the phosphor particles 3.
  • a current value during discharge is 0.1 mA or less. It was confirmed that light emission once started was sustained even when the voltage was decreased to about 50% to 80% of the voltage applied initially, and that a high brightness, a high contrast, a high recognition capability, and a high reliability were ensured in light emission of each of the three colors.
  • the light-emitting element is driven in the atmosphere. However, it was confirmed that even in an atmosphere of oxygen, nitrogen, and an inert gas or in a gas atmosphere under a reduced pressure, the light-emitting element emitted light similarly.
  • the light-emitting element of the present embodiment emits light by surface discharge in the porous light-emitting layer.
  • the light-emitting element unlike a conventional light-emitting element, there is no need to use a thin film formation process for manufacturing the light-emitting element, and neither a vacuum system nor a carrier intensifying layer is necessary. Therefore, the light-emitting element has a simple structure and is manufactured and processed easily. Further, it is possible to provide a light-emitting layer that exhibits favorable luminous efficiency and is to be driven with relatively low power consumption when being applied to a large-screen display.
  • the space is provided as the discharge separation means at a boundary between the porous light-emitting layers, whereby crosstalk during light emission can be avoided in a relatively simple manner.
  • a description will be given of a light-emitting element that is formed of an assembly of a plurality of porous light-emitting layers, each having a dielectric layer and a first electrode on one surface and a second electrode on the other surface where the dielectric layer and the first electrode are not formed, and includes discharge separation means between the plurality of porous light-emitting layers.
  • the following description is directed particularly to the porous light-emitting layer.
  • FIGs. 14 and 15 are schematic enlarged cross-sectional views of the porous light-emitting layer of the present embodiment.
  • reference numeral 2 denotes a porous light-emitting layer
  • 3 denotes a phosphor particle
  • 4 denotes an insulating layer
  • 18 denotes an insulative fiber.
  • the porous light-emitting layer 2 is formed of the phosphor particles and the insulative fibers 18 of ceramic, glass, or the like, regardless of the presence/absence of the insulating layer on a surface of the phosphor particle.
  • An example of the insulative fiber 18 includes a SiO 2 -Al 2 O 3 -CaO based fiber, which preferably has a diameter of 0.1 to 5 ⁇ m and a length of 0.5 to 20 ⁇ m.
  • 1 weight part of fiber having dimensions in the above range is used with respect to 2 weight parts of phosphor particle, whereby the porosity is increased relatively, and accordingly surface discharge occurs easily in the porous light-emitting layer.
  • a kneaded paste containing 45 mass% of ⁇ -terpineol and 5 mass% of ethyl cellulose with respect to 50 mass% of a mixture of the phosphor particles and the insulative fibers is prepared.
  • the paste is screen-printed in a pattern to form the porous light-emitting layer as in Embodiment 1.
  • FIGs. 14 and 15 are schematic enlarged cross-sectional views of the thus-obtained porous light-emitting layer containing the insulative fibers 18.
  • FIG. 15 shows the porous light-emitting layer 2 formed of the phosphor particles 3 and the insulative fibers 18.
  • FIG. 14 shows the porous light-emitting layer formed of the phosphor particles 3, each being coated with the insulating layer 4, and the insulative fibers.
  • the first electrode, the dielectric layer, the second electrode, and the partition wall are formed in the same manner as in Embodiment 1, and finally the same light-emitting element as in Embodiment 1 is manufactured (not shown).
  • a SiO 2 -Al 2 O 3 -CaO based fiber is thermally and chemically stable, has a specific resistance of 10 9 ⁇ •cm or more, achieves easily a high apparent porosity in a range of not less than 10% to less than 100% in the porous light-emitting layer, and allows discharge to occur easily on a surface of the fiber, allowing surface discharge to occur in the entire porous light-emitting layer.
  • an insulative fiber including a fiber of SiC base, ZnO base, TiO 2 base, MgO base, BN base, and Si 3 N 4 base may be used to achieve substantially the same effect.
  • the light emitting action of this light-emitting element is the same as in Embodiment 1.
  • an AC electric field is applied between the first electrode and the second electrode.
  • gas breakdown is caused in the gap 9, and accordingly electrons are generated.
  • surface discharge occurs.
  • Surface discharge occurs continuously during the application of an electric field. Electrons and ultraviolet rays generated in an avalanche manner during the application of an electric field collide with the luminescence center of the phosphors, so that the phosphor particles 3 are excited to emit light.
  • an electric field of about 0.65 to 1.4 kV/mm is applied in a thickness direction of the porous light-emitting layer to allow the phosphor particles 3 to emit light. Thereafter, an alternating electric field of about 0.45 to 0.90 kV/mm is applied, so that surface discharge occurs continuously to sustain the light emission of the phosphor particles 3.
  • an electric field of about 0.65 to 1.4 kV/mm is applied in a thickness direction of the porous light-emitting layer to allow the phosphor particles 3 to emit light.
  • an alternating electric field of about 0.45 to 0.90 kV/mm is applied, so that surface discharge occurs continuously to sustain the light emission of the phosphor particles 3.
  • a current value during discharge is 0.1 mA or less. It was confirmed that light emission once started was sustained even when the voltage was decreased to about 50% to 80% of the voltage applied initially, and that a high brightness, a high contrast, a high recognition capability, and a high reliability were ensured in light emission of each of the three colors.
  • the light-emitting element is driven in the atmosphere. However, it was confirmed that even in an atmosphere of oxygen, nitrogen, and an inert gas or in a gas atmosphere under a reduced pressure, the light-emitting element emitted light similarly.
  • the light-emitting element of the present embodiment emits light by surface discharge in the porous light-emitting layer.
  • the light-emitting element unlike a conventional light-emitting element, there is no need to use a thin film formation process for manufacturing the light-emitting element, and neither a vacuum system nor a carrier intensifying layer is necessary. Therefore, the light-emitting element has a simple structure and is manufactured and processed easily. Further, it is possible to provide a light-emitting layer that exhibits favorable luminous efficiency and is to be driven with relatively low power consumption when being applied to a large-screen display.
  • the partition wall is provided as the discharge separation means at a boundary between the porous light-emitting layers, whereby crosstalk during light emission can be avoided in a relatively simple manner.
  • a description will be given of an operation of a light-emitting element that is formed of an assembly of a plurality of porous light-emitting layers, each having a dielectric layer and an address electrode on one surface and a data electrode on the other surface where the dielectric layer and the address electrode are not formed, and includes discharge separation means between the plurality of porous light-emitting layers.
  • FIG. 16 is an exploded perspective view of the light-emitting element of the present embodiment.
  • the light-emitting element in which the discharge separation means is formed of a gap is shown.
  • reference numeral 1 denotes a light-emitting element
  • 2 denotes a porous light-emitting layer
  • 5 denotes a substrate
  • 8 denotes a transparent substrate
  • 10 denotes a dielectric layer
  • 12 denotes a gap
  • 21 denotes an address electrode
  • 22 denotes a display electrode.
  • the address electrode 21 is formed on the substrate 5, and the plurality of porous light-emitting layers 2, each having the dielectric layer 10, are arranged regularly thereon, whereby an array of the porous light-emitting layers that emit light of three colors R, G, and B, respectively, is formed.
  • the gap 12 is present between the porous light-emitting layers, and a side wall usually is provided (not shown) so as to surround the entire array of the porous light-emitting layers 2.
  • the display electrode 22 is formed so as to be opposed to the porous light-emitting layer 2 and to cross the address electrode 21.
  • the address electrode and the display electrode in the present embodiment may correspond to the first electrode and the second electrode, respectively, in Embodiments 1 to 5, these electrodes may be provided additionally in some cases.
  • the light-emitting element that is formed of an assembly of the plurality of porous light-emitting layers, each having the dielectric layer and the address electrode on one surface and the data electrode on the other surface where the dielectric layer and the address electrode are not formed, and includes the discharge separation means between the plurality of porous light-emitting layers.
  • the discharge separation means is formed of the gap.
  • a two-dimensional image can be displayed on the porous light-emitting layer.
  • the light-emitting element 1 of the present embodiment can be driven in a so-called simple matrix.
  • a pulse signal is transmitted sequentially to an X electrode, and ON/OFF information is input to a Y electrode at a timing of the signal transmission, whereby a pixel at a place where the address electrode and the display electrode cross each other is allowed to emit light in accordance with the ON/OFF information, so that one line is displayed.
  • a two-dimensional image can be displayed by switching scan pulses sequentially.
  • the light-emitting element 1 can be driven more actively.
  • the gap 12 is provided between the porous light-emitting layers, little crosstalk occurs during light emission.
  • a partition wall is provided between the unit light-emitting elements as in Embodiment 1, crosstalk during light emission can be avoided almost completely.
  • FIG. 18 shows a cross section of a display device of the present embodiment.
  • the present embodiment is the same as Embodiment 1 shown in FIG. 1 except for ribs 23a and 23b provided between the partition walls 11.
  • the partition wall 11 has a horizontal thickness of 150 ⁇ m and a height of 270 ⁇ m.
  • the ribs 23a and 23b have a thickness of 50 ⁇ m and a height of 250 ⁇ m.
  • the width of one pixel is 100 ⁇ m.
  • the porous light-emitting layer has a thickness of 230 ⁇ m.
  • the gap (gas layer) 9 has a width of a distance of 20 ⁇ m.
  • the dielectric layer 10 made of BaTiO 3 has a thickness of 250 ⁇ m.
  • a distance between the first electrode 6 and the second electrode 7 is 500 ⁇ m.
  • an electric field (frequency: 1 kHz) of about 0.72 to 1.5 kV/mm is applied in a thickness direction of the porous light-emitting layer to allow the phosphor particles 3 to emit light.
  • an alternating electric field (frequency: 1 kHz) of about 0.4 kV/mm is applied, so that surface discharge occurs continuously to sustain the light emission of the phosphor particles 3.
  • a current value during discharge is 0.1 mA or less. It was confirmed that light emission once started was sustained even when the voltage was decreased to about 50% to 80% of the voltage applied initially, and that a high brightness, a high contrast, a high recognition capability, and a high reliability were ensured in light emission of each of the three colors.
  • the light-emitting element is driven in the atmosphere. However, it was confirmed that even in an atmosphere of oxygen, nitrogen, and an inert gas or in a gas atmosphere under a reduced pressure, the light-emitting element emitted light similarly.
  • FIG. 19 shows a cross section of a display device of the present embodiment.
  • the present embodiment is the same as Embodiment 1 shown in FIG. 1 except that the partition wall 11 is formed by cutting the dielectric layer 10 made of BaTiO 3 .
  • the partition wall 11 has a horizontal thickness of 150 ⁇ m and a height of 270 ⁇ m.
  • the width of one pixel is 250 ⁇ m.
  • the porous light-emitting layer has a thickness of 230 ⁇ m.
  • the gap 9 has a width of 20 ⁇ m.
  • the dielectric layer made of BaTiO 3 has a thickness of 520 ⁇ m.
  • a distance between the first and second electrodes is 500 ⁇ m.
  • an electric field (frequency: 1 kHz) of about 0.72 to 1.5 kV/mm is applied in a thickness direction of the porous light-emitting layer to allow the phosphor particles 3 to emit light.
  • an alternating electric field (frequency: 1 kHz) of about 0.4 kV/mm is applied, so that surface discharge occurs continuously to sustain the light emission of the phosphor particles 3.
  • a current value during discharge is 0.1 mA or less. It was confirmed that light emission once started was sustained even when the voltage was decreased to about 50% to 80% of the voltage applied initially, and that a high brightness, a high contrast, a high recognition capability, and a high reliability were ensured in light emission of each of the three colors.
  • the light-emitting element is driven in the atmosphere. However, it was confirmed that even in an atmosphere of oxygen, nitrogen, and an inert gas or in a gas atmosphere under a reduced pressure, the light-emitting element emitted light similarly.
  • silicone oil was impregnated as in a dielectric breakdown test of a multilayer chip capacitor. Specifically, in a multilayer chip capacitor, a true dielectric breakdown voltage value cannot be measured since surface discharge occurs frequently. To solve this problem, silicone oil was impregnated into fine pore portions of an element, and a true dielectric breakdown voltage value was obtained in a state in which no surface discharge occurred. Based on this method, gas in fine pores in the porous light-emitting layer 2 of the light-emitting element 1 in FIG. 1 was substituted by silicone oil. The fine pores were impregnated with the silicone oil for several minutes, followed by wiping the silicone oil off a surface of the light-emitting element, and an alternating electric field as in Embodiment 1 was applied.
  • the light-emitting layer 2 has fine pores connected to its surface, and that the fine pores are filled with gas or evacuated.
  • the electrons rush into the light-emitting layer 4, the electrons are accelerated while causing surface discharge repeatedly in an avalanche manner along the fine pore portions. Then, the accelerated electrons collide with the luminescence center of the phosphor particles, so that the phosphor particles are excited to emit light.
  • the fine pore portions are filled with silicon oil or a conductive solution, it is difficult for electrons to move, or short circuit occurs, so that no surface discharge occurs, and accordingly no light is emitted.
  • the fine pore portion has a size of several hundreds ⁇ m or less. However, care should be taken when the size of the fine pore portion is several mm or more, since air discharge may occur to destroy the element.
  • the phosphor particles 3 are packed so as to be in point contact with each other. Ideally, it is desirable that the light-emitting layer is porous with an apparent porosity in a range of not less than 10% to less than 100%.
  • the insulating layer 4 is provided for the following reasons:
  • the thickness of the porous light-emitting layer 2 is not particularly limited. However, light emission was observed when the thickness was in a range of 10 ⁇ m to 3 mm caused. It should be appreciated that without the occurrence of short circuit, light is emitted even when the thickness is as small as several ⁇ m.
  • FIG. 22 is a cross-sectional view of the light-emitting element 1 of the present embodiment.
  • Reference numeral 6 denotes a first electrode
  • 7 denotes a second electrode
  • 3 denotes a phosphor particle
  • 4 denotes an electrically insulating layer
  • 2 denotes a porous light-emitting layer
  • 10 denotes a dielectric layer.
  • the porous light-emitting layer 2 is formed of the phosphor particles 3 as a main component, and each of the phosphor particles 3 is coated with the insulating layer 4.
  • three inorganic compounds of BaMgAl 10 O 17 :Eu 2+ (blue), Zn 2 SiO 4 :Mn 2+ (green), and YBO 3 :Eu 3+ (red), each having an average particle diameter of 2 to 3 ⁇ m, can be used as the phosphor particle 3 singly or in a mixture.
  • the blue phosphor particle 3 coated with the insulating layer 4 of an insulative inorganic substance of MgO is used.
  • the phosphor particles are added to an Mg precursor complex solution, stirred, and taken out from the solution, followed by drying. After that, the phosphor particle is subjected to heat treatment at 400°C to 600°C in the atmosphere, whereby a uniform coating layer of MgO shown in FIG. 6 is formed on a surface of the phosphor.
  • the slurry is applied to one surface of the dielectric layer 10 (i.e., a plate-shaped sintered body containing BaTiO 3 as a main component, on a back surface of which an Ag electrode paste is baked to a thickness of about 50 ⁇ m to form the first electrode 6) with a diameter of 15 mm ⁇ and a thickness of 1 mm, on the other surface of which the second electrode 7 is formed, and drying is carried out with a dryer at 100°C to 150°C for 10 to 30 minutes.
  • the porous light-emitting layer 2 with a thickness of about 100 ⁇ m is laminated on the dielectric layer 10.
  • the transparent substrate (glass plate) 8 to which the transparent second electrode (indium-tin oxide alloy (ITO), thickness: about 0.1 ⁇ m) 7 is applied is laminated. Consequently, the light-emitting element 1 in which a pair of the electrodes 6 and 7 are formed so as to sandwich the dielectric layer 10 and the porous light-emitting layer 2 therebetween is obtained.
  • ITO indium-tin oxide alloy
  • polarization reversal is performed repeatedly in the dielectric layer. Accordingly, electrons are generated, and as a result of electric charge being injected into the porous light-emitting layer, surface discharge occurs. Surface discharge occurs continuously during the application of an electric field. Electrons and ultraviolet rays generated in an avalanche manner during the application of an electric field collide with the luminescence center of the phosphors, so that the phosphor particles 3 are excited to emit light.
  • the primary electrons (e-) 24 are emitted due to polarization reversal and the secondary electrons (e-) 25 are generated due to surface discharge, followed by light emission.
  • a current value during discharge is 0.1 mA or less. It was confirmed that light emission once started was sustained even when the voltage was decreased to 50% to 80% of the voltage applied initially, and that a high brightness, a high contrast, a high recognition capability, and a high reliability were ensured in light emission. Further, it becomes possible to manufacture a light-emitting device with luminous efficiency of about 2 to 5 lm/w.
  • the light-emitting element is driven in the atmosphere. However, it was confirmed that even in an atmosphere of oxygen, nitrogen, and an inert gas or in a gas atmosphere under a reduced pressure, the light-emitting element emitted light similarly.
  • the light-emitting element 1 of the present embodiment has a structure similar to that of an inorganic EL display (ELD), but has a completely different configuration and mechanism.
  • a phosphor used in an inorganic EL display is a light-emitting body formed of a semiconductor such as ZnS : Mn 2+ and GaP : N as described in the background art section.
  • the phosphor particle in Embodiment 9 may be either an insulator or a semiconductor.
  • a phosphor layer has a thickness of submicron to several ⁇ m.
  • the phosphor layer in Embodiment 9 has a porous structure with a thickness of several ⁇ m to several hundreds ⁇ m. Further, in Embodiment 9, the light-emitting layer has a porous structure.
  • the phosphor particles are packed so as to be in point contact with each other.
  • the phosphor particle powder that emits ultraviolet rays, which is used in current plasma display panels (PDPs).
  • PDPs current plasma display panels
  • ZnS:Ag blue
  • ZnS:Cu gold
  • Au gold
  • Al green
  • Y 2 O 3 red
  • the phosphor for use in CRTs has a low resistance value
  • surface discharge is less likely to occur.
  • the coating of the insulating layer 4 allows surface discharge to occur easily, and accordingly light is emitted easily.
  • the light-emitting element of the present invention emits light by surface discharge that occurs in an avalanche manner due to electrons emitted by polarization reversal in the dielectric.
  • the light-emitting element is expected to emit light easily.
  • a colloidal silica solution is used to form the slurry of the phosphor particles 3.
  • an organic solvent A kneaded slurry containing 45 mass% of ⁇ -terpineol and 5 mass% of ethyl cellulose with respect to 50 mass% of the phosphor particle is used and screen-printed on a surface of the dielectric layer 10.
  • the thus-obtained substrate is subjected to heat treatment at 400°C to 600°C for 10 to 60 minutes in the atmosphere, whereby the porous light-emitting layer 23 with a thickness of several ⁇ m to several tens ⁇ m can be formed.
  • controlling temperature and heat treatment atmosphere is important since the phosphor is likely to be deteriorated when the heat treatment temperature is increased excessively.
  • the organic slurry may contain inorganic fibers 18 to achieve the same effect.
  • the dielectric layer may be formed of a sintered body or may be formed by sputtering, CVD, deposition or with a thin film formation process such as a sol-gel process.
  • the dielectric layer is formed of a sintered body.
  • light emission is also possible when the dielectric layer is formed of dielectric fine particles and a binder. More specifically, it is possible to use a dielectric layer of dielectric particles and a binder that is formed as follows. A slurry of fine particles in which 15 mass% of glass powder is mixed with respect to 40 mass% of BaTiO 3 powder, the fine particles being kneaded with 40 mass% of ⁇ -terpineol and 5 mass% of ethyl cellulose, is applied to an Al metal substrate, followed by drying. Then, the thus-obtained substrate is subjected to heat treatment at 400°C to 600°C in the atmosphere.
  • the blue phosphor particle is used. However, it was found that the same effect also was achieved by using a red or green phosphor particle. Further, mixed particles of blue, red, and green also achieve the same effect.
  • the light-emitting element of the present embodiment emits light by surface discharge.
  • a conventional light-emitting element there is no need to use a thin film formation process for forming the phosphor layer, and neither a vacuum system nor a carrier intensifying layer is necessary. Therefore, the light-emitting element has a simple structure and is processed easily.
  • ITO is used for the electrode 7.
  • copper wiring may be provided on the transparent substrate. Copper wiring is formed in a microporous mesh shape and has an open area ratio (ratio of a portion where no wiring is provided to the entire substrate) of 90%, and accordingly this substrate allows light to pass therethrough approximately as favorably as the transparent substrate with the ITO film. Further, copper is favorable since it has a much lower resistance than ITO and greatly contributes to increased luminous efficiency.
  • gold, silver, platinum, or aluminum can be used instead of copper.
  • a mesh-shaped (about 5 to 10 mesh) Ag paste is printed and baked on one surface of the dielectric 10 used in FIG. 22, on the other surface of which the first electrode 6 is formed, whereby the second electrode 7 is formed. Then, as stated above, a slurry of the phosphor particle powder 3 and a colloidal silica solution is applied to a top surface of the second electrode 7, and drying is carried out with a dryer at 100°C to 150°C for 10 to 30 minutes.
  • the porous light-emitting layer 2 with a thickness of about 100 ⁇ m is laminated on a surface of the dielectric layer 10. Consequently, the light-emitting element 1 in which the second electrode 7 is formed between the dielectric layer 10 and the porous light-emitting layer 2 and the first electrode 6 is formed exteriorly so as to sandwich the dielectric layer 10 against the second electrode 7 is obtained.
  • This light-emitting element emits light in the same manner as that in FIG. 22. That is, an AC electric field is applied between the first electrode 6 and the second electrode 7.
  • polarization reversal is performed in the dielectric layer 10, and accordingly primary electrons (e-) 24 are emitted. At this time, ultraviolet rays and visible light are generated.
  • the primary electrons (e-) collide with the phosphor particles 3 and the insulating layers 4 of the porous light-emitting layer 2 to cause surface discharge, and a large number of secondary electrons (e-) 25 are generated.
  • Electrons and ultraviolet rays generated thereby in an avalanche manner collide with the luminescence center of the phosphors, so that the phosphor particles 3 are excited to emit light.
  • polarization reversal is performed repeatedly in the dielectric layer. Accordingly, electrons are generated, and as a result of electric charge being injected into the porous light-emitting layer, surface discharge occurs. Surface discharge occurs continuously during the application of an electric field.
  • Electrons and ultraviolet rays generated in an avalanche manner during the application of an electric field collide with the luminescence center of the phosphors, so that the phosphor particles 3 are excited to emit light.
  • the alternating electric field to be applied has its waveform changed from a sine wave or a sawtooth wave to a rectangular wave or has its frequency increased by several tens to thousands of Hz, electrons are emitted by polarization reversal and surface discharge occurs more vigorously, resulting in increased emission brightness. Further, as a voltage value of the alternating electric field is increased, a burst wave is generated.
  • a burst wave which is generated when polarization reversal is performed in the dielectric layer 10, is generated at a frequency immediately before the peak of the frequency in the case of a sine wave, and is generated at the peak of the frequency in the case of a sawtooth wave or a rectangular wave, and the emission brightness increases with increasing peak voltage of the burst wave.
  • the second electrode 7 has a mesh shape so as to allow the primary electrons (e-) 24 generated by polarization reversal as shown in FIG. 17 to be emitted easily in the porous light-emitting layer 2. If the electrode 7 is formed to have a uniform thickness, the primary electrons (e-) 24 shown in FIG. 17 are less likely to be emitted in the porous light-emitting layer 2.
  • the colloidal silica used as a binder functions as the insulating layer 4.
  • FIG. 24 is a cross-sectional view of the light-emitting element 1 of Embodiment 11.
  • Reference numeral 6 denotes a first electrode
  • 7 denotes a second electrode
  • 3 denotes a phosphor particle
  • 2 denotes a porous light-emitting layer
  • 10 denotes a dielectric layer.
  • the porous light-emitting layer 2 is formed of a material containing the phosphor particles 3 and ceramic fibers 18 as main components.
  • an Ag paste is applied to and baked on one surface of the sintered dielectric 10 used in FIG. 22, so that a pair of the electrodes 6 and 7 are formed. Then, a kneaded slurry containing 45 mass% of the phosphor particle, 10 mass% of inorganic fiber powder, 40 mass% of ⁇ -terpineol, and 5 mass% of ethyl cellulose is applied, followed by drying.
  • the thus-obtained dielectric 10 is subjected to heat treatment at 400°C to 600°C, whereby the porous light-emitting layer 2 with a thickness of about 50 ⁇ m is laminated on the dielectric layer 10. Consequently, the light-emitting element 1 in which a pair of the electrodes 6 and 7 both are formed at the boundary between the dielectric layer 10 and the porous light-emitting layer 2 is obtained.
  • This light-emitting element emits light in the same manner as that in FIG. 22. That is, an AC electric field is applied between the first electrode 6 and the second electrode 7. By the application of a voltage, polarization reversal is performed in the dielectric layer 10, and accordingly primary electrons (e-) 24 are emitted. At this time, ultraviolet rays and visible light are generated. The primary electrons (e ⁇ ) collide with the phosphor particles 3 and the ceramic fibers 18 of the porous light-emitting layer 2 to cause surface discharge, and a large number of secondary electrons (e-) 25 are generated.
  • polarization reversal is performed repeatedly in the dielectric layer. Accordingly, electrons are generated, and as a result of electric charge being injected into the porous light-emitting layer, surface discharge occurs. Surface discharge occurs continuously during the application of an electric field. Electrons and ultraviolet rays generated in an avalanche manner during the application of an electric field collide with the luminescence center of the phosphors, so that the phosphor particles 3 are excited to emit light.
  • the alternating electric field to be applied has its waveform changed from a sine wave or a sawtooth wave to a rectangular wave or has its frequency increased by several tens to thousands of Hz, electrons are emitted by polarization reversal and surface discharge occurs more vigorously, resulting in increased emission brightness. Further, as a voltage value of the alternating electric field is increased, a burst wave is generated.
  • a burst wave which is generated when polarization reversal is performed in the dielectric layer 10, is generated at a frequency immediately before the peak of the frequency in the case of a sine wave, and is generated at the peak of the frequency in the case of a sawtooth wave or a rectangular wave, and the emission brightness increases with increasing peak voltage of the burst wave.
  • FIG. 24 shows the case where a pair of electrodes both are formed at the boundary between the dielectric layer and the porous light-emitting layer.
  • a pair of the electrodes 6 and 7 are arranged on a top surface of a dielectric layer, the porous light-emitting layer 2 is laminated on the dielectric layer via a pair of the electrodes, and another electrode 70 is arranged on a top surface of the porous light-emitting layer 2.
  • FIG. 25 is a cross-sectional view of the light-emitting element 1 of the present embodiment.
  • Reference numerals 6 and 7 denote a first electrode and a second electrode, respectively, as a pair of electrodes.
  • Reference numeral 3 denotes a phosphor particle
  • 4 denotes an electrically insulating layer
  • 2 denotes a porous light-emitting layer
  • 10 denotes a dielectric layer
  • 70 denotes a third electrode.
  • the porous light-emitting layer is formed of the phosphor particles 3 or a material containing the phosphor particles 3 as a main component.
  • the phosphor particle 3 coated with the insulating layer 4 is used.
  • the blue phosphor particle 3 coated with the insulating layer 4 of an insulative inorganic substance of MgO is used.
  • the phosphor particles 11 are added to an Mg precursor complex solution, stirred for a long time, and taken out from the solution, followed by drying. After that, the phosphor particle is subjected to heat treatment at 400°C to 600°C in the atmosphere, whereby a uniform coating layer of MgO, i.e., the insulating layer 4, is formed on a surface of the phosphor particle 3.
  • the slurry is applied to the dielectric layer 10 (i.e., a plate-shaped sintered body containing BaTiO 3 as a main component, on a top surface of which an Ag electrode paste is baked to a thickness of 30 ⁇ m to form the first electrode 6 and the second electrode 7) with a diameter of 15 mm ⁇ and a thickness of 1 mm, on which the first electrode 6 and the second electrode 7 are formed, via a pair of the electrodes, i.e., the first electrode 6 and the second electrode 7, and drying is carried out with a dryer at 100°C to 150°C for 10 to 30 minutes.
  • the porous light-emitting layer 2 with a thickness of about 100 ⁇ m is laminated on the dielectric layer 10.
  • a glass (not shown) to which the transparent electrode (indium-tin oxide alloy (ITO), thickness: 0.1 ⁇ m) 70 is applied is laminated. Consequently, the light-emitting element 1 as shown in FIG. 25 in which a pair of the electrodes 6 and 7 are formed at a boundary between the dielectric layer 10 and the porous light-emitting layer 2 and the third electrode 70 is formed on the top surface of the porous light-emitting layer is obtained.
  • an inorganic fiber board supporting phosphor particle powder may be used as the porous light-emitting layer.
  • Electrons and ultraviolet rays generated thereby in an avalanche manner collide with the luminescence center of the phosphors, so that the phosphor particles 3 are excited to emit light.
  • polarization reversal is performed repeatedly in the dielectric layer. Accordingly, electrons are generated, and as a result of electric charge being injected into the porous light-emitting layer, surface discharge occurs. Surface discharge occurs continuously during the application of an electric field. Electrons and ultraviolet rays generated in an avalanche manner during the application of an electric field collide with the luminescence center of the phosphors, so that the phosphor particles 3 are excited to emit light.
  • a burst wave which is generated when polarization reversal is performed in the dielectric layer 10, is generated at a frequency immediately before the peak of the frequency in the case of a sine wave, and is generated at the peak of the frequency in the case of a sawtooth wave or a rectangular wave, and the emission brightness increases with increasing voltage of the burst wave.
  • an electric field of about 0.65 to 1.3 kV/mm is applied in a thickness direction of the dielectric layer 10 for polarization reversal. Thereafter, an alternating electric field of about 0.5 to 1.0 kV/mm is applied in a thickness direction of the light-emitting element 1 by using an AC power supply.
  • an alternating electric field of about 0.5 to 1.0 kV/mm is applied in a thickness direction of the light-emitting element 1 by using an AC power supply.
  • a current value during discharge is 0.1 mA or less. It was confirmed that light emission once started was sustained even when the voltage was decreased to 50% to 80% of the voltage applied initially, and that a high brightness, a high contrast, a high recognition capability, and a high reliability were ensured in light emission. It becomes possible to manufacture a light-emitting device with luminous efficiency of 2 to 5 lm/W with respect to blue light.
  • the light-emitting element is driven in the atmosphere. However, it was confirmed that even in an atmosphere of oxygen, nitrogen, and an inert gas or in a gas atmosphere under a reduced pressure, the light-emitting element emitted light similarly.
  • the light-emitting element 1 of Embodiment 12 has a structure similar to that of an inorganic EL display (ELD), but has a completely different configuration and mechanism.
  • a phosphor used in an inorganic EL display is a light-emitting body formed of a semiconductor such as ZnS : Mn 2+ and GaP : N as described in the background art section.
  • the phosphor particle in Embodiment 1 may be either an insulator or a semiconductor.
  • a phosphor layer has a thickness of submicron to several ⁇ m.
  • the phosphor layer in the present embodiment has a porous structure with a thickness of several ⁇ m to several hundreds ⁇ m.
  • the light-emitting layer has a porous structure.
  • the phosphor particles are packed so as to be in point contact with each other.
  • the phosphor particle powder that emits ultraviolet rays, which is used in current plasma display panels (PDPs).
  • PDPs current plasma display panels
  • ZnS:Ag blue
  • ZnS:Cu gold
  • Au gold
  • Al green
  • Y 2 O 3 red
  • the phosphor for use in CRTs has a low resistance value
  • surface discharge is less likely to occur.
  • the light-emitting element of the present invention emits light by surface discharge that occurs in an avalanche manner due to primary electrons emitted by polarization reversal in the dielectric, followed by the generation of a large number of secondary electrons.
  • the light-emitting element is expected to emit light easily.
  • a colloidal silica solution is used to form the slurry of the phosphor particles 3.
  • an organic solvent A kneaded slurry containing 45 mass% of ⁇ -terpineol and 5 mass% of ethyl cellulose with respect to 50 mass% of the phosphor particle is used and screen-printed on a surface of the dielectric layer 10.
  • the thus-obtained substrate is subjected to heat treatment at 400°C to 600°C for 10 to 60 minutes in the atmosphere, whereby the porous light-emitting layer 23 with a thickness of several ⁇ m to several tens ⁇ m can be formed.
  • controlling temperature and heat treatment atmosphere is important since the phosphor is likely to be deteriorated when the heat treatment temperature is increased excessively.
  • the organic slurry may contain inorganic fibers 18 to achieve the same effect.
  • the dielectric layer may be formed of a sintered body or may be formed by sputtering, CVD, deposition or with a thin film formation process such as a sol-gel process.
  • the dielectric layer is formed of a sintered body.
  • light emission is also possible when the dielectric layer is formed of dielectric fine particles and a binder. More specifically, it is possible to use a dielectric layer of dielectric particles and a binder that is formed as follows. A slurry of fine particles in which 15 mass% of glass powder is mixed with respect to 40 mass% of BaTiO 3 powder, the fine particles being kneaded with 40 mass% of ⁇ -terpineol and 5 mass% of ethyl cellulose, is applied to an Al metal substrate, followed by drying. Then, the thus-obtained substrate is subjected to heat treatment at 400°C to 600°C in the atmosphere.
  • the blue phosphor particle is used.
  • a red or green phosphor particle is used.
  • mixed particles of blue, red, and green also achieve the same effect.
  • the light-emitting element of the present embodiment emits light by surface discharge.
  • the light-emitting element has a simple structure and is processed easily.
  • ITO is used for the electrode 70.
  • copper wiring may be provided on the transparent substrate. Copper wiring is formed in a microporous mesh shape and has an open area ratio (ratio of a portion where no wiring is provided to the entire substrate) of 90%, and accordingly this substrate allows light to pass therethrough approximately as favorably as the transparent substrate with the ITO film. Further, copper is favorable since it has a much lower resistance than ITO and greatly contributes to increased luminous efficiency.
  • gold, silver, platinum, or aluminum can be used instead of copper.
  • the first electrode 6 and the second electrode 7 are formed on a bottom surface and a top surface, respectively, of the dielectric layer 10. Descriptions for the same reference numerals as in FIG. 1 may be omitted.
  • the second electrode 7 is formed in a central portion on the top surface, and the first electrode 6 is formed on the entire bottom surface by printing and baking an Ag paste as in Embodiment 12.
  • the slurry containing the phosphor particles 3 as used in Embodiment 12 is applied to a surface of the second electrode 7, and drying is carried out with a dryer at 100°C to 150°C for 10 to 30 minutes.
  • the porous light-emitting layer 2 with a thickness of about 100 ⁇ m is laminated on the dielectric layer 10.
  • a glass plate (not shown) to which the transparent electrode 70 (indium-tin oxide alloy (ITO), thickness: 0.1 ⁇ m) is applied is laminated as in Embodiment 12. Consequently, the light-emitting element 1 with a cross-sectional structure as shown in FIG.
  • the porous light-emitting layer 2 is laminated on the top surface of the dielectric 10 via the second electrode 7, and the third electrode 70 is formed on the top surface of the porous light-emitting body, is obtained.
  • an AC electric field is applied between the first electrode 6 and the second electrode 7.
  • polarization reversal is performed in the dielectric layer 10, and accordingly primary electrons (e-) 24 are emitted.
  • primary electrons (e-) 24 are emitted.
  • ultraviolet rays and visible light are generated.
  • an alternating electric field is applied between the third electrode 70 and at least one of a pair of the electrodes.
  • the primary electrons (e ⁇ ) collide with the phosphor particles 3 and the insulating layers 4 of the porous light-emitting layer 2 to cause surface discharge, and a large number of secondary electrons (e-) 25 are generated.
  • polarization reversal is performed repeatedly in the dielectric layer. Accordingly, electrons are generated, and as a result of electric charge being injected into the porous light-emitting layer, surface discharge occurs. Surface discharge occurs continuously during the application of an electric field. Electrons and ultraviolet rays generated in an avalanche manner during the application of an electric field collide with the luminescence center of the phosphors, so that the phosphor particles 3 are excited to emit light.
  • Embodiment 13 as described in Embodiment 12, when the alternating electric field to be applied has its waveform changed from a sine wave or a sawtooth wave to a rectangular wave or has its frequency increased by several tens to thousands of Hz, electrons are emitted by polarization reversal and surface discharge occurs more vigorously, resulting in increased emission brightness. Further, as a voltage value of the alternating electric field is increased, a burst wave is generated.
  • a burst wave which is generated when polarization reversal is performed in the dielectric layer 10, is generated at a frequency immediately before the peak of the frequency in the case of a sine wave, and is generated at the peak of the frequency in the case of a sawtooth wave or a rectangular wave, and the emission brightness increases with increasing peak voltage of the burst wave.
  • Embodiment 13 when a voltage of about 0.84 to 1.4 kV/mm is applied between the first electrode 6 and the second electrode 7 in a thickness direction of the dielectric layer 10, primary electrons are emitted due to polarization reversal. Thereafter, when an alternating electric field of about 0.7 to 1.2 kV/mm is applied between at least one of the first electrode 6 and the second electrode 7 and the electrode 70 in a thickness direction of the light-emitting element 1, surface discharge occurs and a large number of secondary electrons are generated, followed by light emission.
  • a current value during discharge is 0.1 mA or less. It was confirmed that light emission once started was sustained even when the voltage was decreased to 50% to 80% of the voltage applied initially, and that a high brightness, a high contrast, a high recognition capability, and a high reliability were ensured in light emission. It becomes possible to manufacture a light-emitting device with luminous efficiency of 2 to 5 lm/W with respect to blue light.
  • the second electrode 7 is formed not on the entire top surface of the dielectric layer 10 but in a certain portion on the top surface thereof. This prevents primary electrons emitted by polarization reversal from being blocked by the electrode itself and allows the primary electrons to be introduced into the porous light-emitting layer 2 efficiently.
  • the electrode may have any shape, such as a mesh shape, as long as electrons generated by polarization reversal are emitted to the porous light-emitting layer 2 smoothly.
  • Embodiment 14 will be described with reference to FIG. 27.
  • a pair of the electrodes 6 and 7 are arranged on a bottom surface of the dielectric layer 10, the porous light-emitting layer 2 is laminated on a top surface thereof, and the third electrode 70 is arranged on a top surface of the porous light-emitting layer 2.
  • the phosphor particle is coated with the insulating layer 4.
  • a uniform coating layer of MgO is formed on a surface of the phosphor particle.
  • a method for manufacturing the light-emitting element of the present embodiment will be described with reference to FIG. 27.
  • 50 mass% of the phosphor particle 11 coated uniformly with the insulating layer 4 and 50 mass% of a colloidal silica solution are mixed to form a slurry.
  • the slurry is applied to a top surface of the dielectric layer 10 (i.e., a plate-shaped sintered body containing BaTiO 3 as a main component, on a bottom surface of which an Ag electrode paste is baked to a thickness of 30 ⁇ m to form the first electrode 6 and the second electrode 7) with a diameter of 15 mm ⁇ and a thickness of 1 mm, on which the first electrode 6 and the second electrode 7 are formed, and drying is carried out with a dryer at 100°C to 150°C for 10 to 30 minutes.
  • the porous light-emitting layer 2 with a thickness of about 100 ⁇ m is laminated on the dielectric layer 10.
  • a glass (not shown) to which the transparent electrode (indium-tin oxide alloy (ITO), thickness: 0.1 ⁇ m) 70 is applied is laminated on a top surface of the porous light-emitting layer 2. Consequently, the light-emitting element 1 as shown in FIG. 27 in which a pair of the electrodes 6 and 7 are formed on the bottom surface of the dielectric layer 10, the porous light-emitting layer 2 is laminated on the top surface of the dielectric layer 10, and the third electrode 70 is formed on the top surface of the porous light-emitting layer 2 is obtained.
  • ITO indium-tin oxide alloy
  • polarization reversal is performed repeatedly in the dielectric layer. Accordingly, electrons are generated, and as a result of electric charge being injected into the porous light-emitting layer, surface discharge occurs. Surface discharge occurs continuously during the application of an electric field. Electrons and ultraviolet rays generated in an avalanche manner during the application of an electric field collide with the luminescence center of the phosphors, so that the phosphor particles 3 are excited to emit light.
  • a burst wave which is generated when polarization reversal is performed in the dielectric layer 10, is generated at a frequency immediately before the peak of the frequency in the case of a sine wave, and is generated at the peak of the frequency in the case of a sawtooth wave or a rectangular wave, and the emission brightness increases with increasing voltage of the burst wave.
  • an electric field of about 0.4 to 0.8 kV/mm is applied in a thickness direction of the dielectric layer 10 for polarization reversal. Thereafter, an alternating electric field of about 0.5 to 1.0 kV/mm is applied in a thickness direction of the light-emitting element 1 by using an AC power supply. As a result, primary electrons are emitted and surface discharge occurs, followed by light emission. When a higher electric field is applied for polarization reversal, the generation of electrons is accelerated, and when an excessively low electric field is applied, the emission of electrons is insufficient.
  • a current value during discharge is 0.1 mA or less. It was confirmed that light emission once started was sustained even when the voltage was decreased to 50% to 80% of the voltage applied initially, and that a high brightness, a high contrast, a high recognition capability, and a high reliability were ensured in light emission. It becomes possible to manufacture a light-emitting device with luminous efficiency of 2 to 5 lm/W with respect to blue light.
  • Embodiment 15 of the present invention will be described with reference to FIG. 28.
  • the first electrode 6 is arranged on a bottom surface of the dielectric layer 10
  • the porous light-emitting layer 2 is laminated on a top surface of the dielectric layer 10
  • the second electrode 7 and the third electrode 70 are arranged on a top surface of the porous light-emitting layer 2.
  • the phosphor particle is coated with the insulating layer 4.
  • a uniform coating layer of MgO is formed on a surface of a blue phosphor particle in the same manner as in Embodiment 12.
  • the light-emitting element of Embodiment 15 is manufactured as follows. Initially, 50 mass% of the phosphor particle 3 coated uniformly with the insulating layer 4 and 50 mass% of a colloidal silica solution are mixed to form a slurry. Then, the slurry is applied to a top surface of the dielectric layer 10 (i.e., a plate-shaped sintered body containing BaTiO 3 as a main component, on a bottom surface of which an Ag electrode paste is baked to a thickness of 30 ⁇ m to form the first electrode 6) with a diameter of 15 mm ⁇ and a thickness of 1 mm, on which the first electrode 6 is formed, and drying is carried out with a dryer at 100°C to 150°C for 10 to 30 minutes.
  • a top surface of the dielectric layer 10 i.e., a plate-shaped sintered body containing BaTiO 3 as a main component, on a bottom surface of which an Ag electrode paste is baked to a thickness of 30 ⁇ m to form the
  • the porous light-emitting layer 2 with a thickness of about 100 ⁇ m is laminated on the dielectric layer 10. Further, on a top surface of the porous light-emitting layer 2, an Ag electrode paste is baked to a thickness of 30 ⁇ m to form the second electrode 7 in a portion on the surface of the porous light-emitting layer 2, and then a glass plate (not shown) to which the transparent electrode (indium-tin oxide alloy (ITO), thickness: 0.1 ⁇ m) 70 is applied partially is laminated. Consequently, the light-emitting element 1 with a cross-sectional structure as shown in FIG.
  • ITO indium-tin oxide alloy
  • polarization reversal is performed repeatedly in the dielectric layer. Accordingly, electrons are generated, and as a result of electric charge being injected into the porous light-emitting layer, surface discharge occurs. Surface discharge occurs continuously during the application of an electric field. Electrons and ultraviolet rays generated in an avalanche manner during the application of an electric field collide with the luminescence center of the phosphors, so that the phosphor particles 3 are excited to emit light.
  • a burst wave which is generated when polarization reversal is performed in the dielectric layer 10, is generated at a frequency immediately before the peak of the frequency in the case of a sine wave, and is generated at the peak of the frequency in the case of a sawtooth wave or a rectangular wave, and the emission brightness increases with increasing voltage of the burst wave.
  • an electric field of about 0.5 to 1.0 kV/mm is applied in a thickness direction of the dielectric layer 10 for polarization reversal. Thereafter, an alternating electric field of about 0.5 to 1.0 kV/mm is applied in a thickness direction of the light-emitting element 1 by using an AC power supply.
  • an AC power supply As a result, primary electrons are emitted, surface discharge occurs, and a large number of secondary electrons are generated, followed by light emission.
  • a higher electric field is applied for polarization reversal, the generation of electrons is accelerated, and when an excessively low electric field is applied, the emission of electrons is insufficient.
  • a current value during discharge is 0.1 mA or less. It was confirmed that light emission once started was sustained even when the voltage was decreased to 50% to 80% of the voltage applied initially, and that a high brightness, a high contrast, a high recognition capability, and a high reliability were ensured in light emission. It becomes possible to manufacture a light-emitting device with luminous efficiency of 2 to 5 lm/W with respect to blue light.
  • a light-emitting element including an electron-emitting body, a porous light-emitting body, and a pair of electrodes according to the present embodiment will be described with reference to FIGs. 29 and 30.
  • the porous light-emitting body includes inorganic phosphor particles and is arranged adjacent to the electron-emitting body so as to be irradiated with electrons generated from the electron-emitting body, and a pair of the electrodes are arranged so that an electric field is applied to at least a part of the porous light-emitting body.
  • the electron-emitting body includes a cathode electrode, a gate electrode, and a Spindt-type emitter interposed between the two electrodes, and electrons emitted from the Spindt-type emitter by the application of a gate voltage between the cathode electrode and the gate electrode are irradiated to the porous light-emitting body, whereby the porous light-emitting body is allowed to emit light.
  • FIG. 29 is a cross-sectional view of the light-emitting element of the present embodiment.
  • Reference numeral 1 denotes a light-emitting element with an overall thickness of about 2 mm
  • 2 denotes a porous light-emitting layer with a thickness of about 30 ⁇ m
  • 3 denotes a phosphor particle with an average particle diameter of 2 ⁇ m
  • 4 denotes an insulating layer with a thickness of 0.5 ⁇ m provided on a surface of the phosphor particle
  • 100 denotes a triangular pyramid Spindt-type emitter with a bottom surface of 1 ⁇ m and a height of 1 ⁇ m
  • 6 denotes a first electrode with a thickness of 200 nm
  • 7 denotes a second electrode with a thickness of 200 nm
  • 111 denotes an anode electrode with a thickness of 150 nm
  • 112 denotes a cathode electrode with a thickness of 150 nm
  • 113
  • FIGs. 30A to 30F are views for explaining the manufacturing method of the light-emitting element shown in FIG. 29.
  • Au is deposited on a surface of the substrate 117 made of glass to form the cathode electrode 112.
  • the cathode electrode 112 Ag, Al, or Ni may be deposited instead of Au.
  • the substrate 117 may be made of ceramic instead of glass.
  • the insulating layer 116 is formed by using a so-called photolithography technique. That is, the cathode electrode is coated with SiO 2 by sputtering, the thus-obtained substrate is exposed to UV light using a photoresist and a photomask to be developed, and etching is performed, whereby the insulating layer 116 is formed selectively.
  • Al is sputtered to form a film, and the gate electrode 113 of Al is formed on the insulating layer 116 by using a photolithography technique.
  • Ni may be used instead of Al.
  • the Spindt-type emitter is formed in a recess between the gate electrode 113 by a two-step deposition method.
  • the substrate shown in FIG. 30C is placed in a deposition device while being tilted at an angle of about 20°, and Al 2 O 3 as a sacrificial material is deposited while the substrate is rotated.
  • Al 2 O 3 is deposited so as to coat the gate electrode 113 and forms an Al 2 O 3 layer 118 with a thickness of 200 nm, with no Al 2 O 3 deposited on the cathode electrode 112.
  • a metal such as Nb, Zr, Ni, and molybdenum steel may be used instead of Mo, and the emitter of these materials can be manufactured based on the above-mentioned method used for the emitter of Mo.
  • the porous light-emitting body 2 is formed of the phosphor particles 3 or a material containing the phosphor particles 3 as a main component, and the phosphor particle 3 coated with the insulating layer 4 is used.
  • three inorganic compounds of BaMgAl 10 O 17 :Eu 2+ (blue), Zn 2 SiO 4 :Mn 2+ (green), and YBO 3 :Eu 3+ (red), each having an average particle diameter of 2 to 3 ⁇ m, for example, can be used as the phosphor particle 3 singly or in a mixture.
  • the blue phosphor particle 3 is used, and the insulating layer 4 of an insulative inorganic substance of MgO is formed on its surface.
  • the phosphor particles 3 are added to an Mg precursor complex solution, stirred for a long time, and taken out from the solution, followed by drying. After that, the phosphor particle is subjected to heat treatment at 400°C to 600°C in the atmosphere, whereby a uniform coating layer of MgO, i.e., the insulating layer 4, is formed on the surface of the phosphor particle 3.
  • 50 mass% of the phosphor particle 3 coated with the insulating layer 4 and 50 mass% of a colloidal silica solution are mixed to form a slurry.
  • a ceramic board formed of inorganic fiber (an Al 2 O 3 -CaO-SiO 2 based ceramic fiber board with a thickness of about 1 mm and a void ratio of about 45%) is immersed in the slurry, followed by drying at 100°C to 150°C for 10 to 30 minutes.
  • the ceramic board supports phosphor particle powder.
  • an Ag electrode paste is baked to a thickness of 30 ⁇ m to form the first electrode 6 and the second electrode 7.
  • the ceramic fiber board thus obtained is attached to the electron-emitting body 119 by using colloidal silica, water glass, or an epoxy resin.
  • the porous light-emitting body 2 On a top surface of the porous light-emitting body 2, a glass (not shown) to which the transparent anode electrode (indium-tin oxide alloy (ITO), thickness: 15 ⁇ m) 111 is applied is laminated. Consequently, the light-emitting element 1 as shown in FIG. 29 in which the porous light-emitting body 2 is formed on the electron-emitting body 119 and the electrodes are arranged at predetermined positions is obtained. Regarding the electrodes of the light-emitting element 1, the first electrode 6 and the second electrode 7 are inserted as auxiliary electrodes since the transparent electrode of ITO used as the anode electrode 111 has a high resistance value. Thus, it is possible to form the anode electrode 11 and the second electrode 7 as one electrode or the gate electrode 113 and the first electrode 6 as one electrode.
  • ITO indium-tin oxide alloy
  • an Ag paste may be screen-printed on the gate electrode so as to form a focusing electrode.
  • a direct electric field of 800 V and 80 V is applied between the anode electrode 111 and the cathode electrode 112 and between the gate electrode 113 and the cathode electrode 112, respectively, in FIG. 29, so that primary electrons are emitted from the Spindt-type emitter 100 in the direction of an arrow in the figure.
  • a higher electric field is applied, the generation of electrons is accelerated, and when an excessively low electric field is applied, the emission of electrons is insufficient.
  • an alternating electric field is applied between the first electrode 6 and the second electrode 7.
  • Primary electrons emitted due to electric charge transfer are doubled in an avalanche manner, and cause surface discharge in the porous light-emitting body 2.
  • Surface discharge occurs continuously in a chain reaction, so that electric charge transfer is carried out in the vicinity of the phosphor particles.
  • ultraviolet rays and visible light also are generated, and the porous light-emitting body 2 also is excited to emit light by the ultraviolet rays.
  • the alternating electric field to be applied has its waveform changed from a sine wave or a sawtooth wave to a rectangular wave and has its frequency increased by several tens to thousands of Hz, electrons are emitted and surface discharge occurs more vigorously, resulting in increased emission brightness.
  • a current value during discharge is 0.1 mA or less. It was confirmed that light emission once started was sustained even when the voltage was decreased to 50% to 80% of the voltage applied initially, and that a high brightness, a high contrast, a high recognition capability, and a high reliability were ensured in light emission. Consequently, it is possible to manufacture a light-emitting device with luminous efficiency of 2.0 lm/W, a brightness of 200 cd/m 2 , and a contrast of 500 : 1 with respect to blue light.
  • the light-emitting element is driven in the atmosphere. However, it was confirmed that even in an atmosphere of oxygen, nitrogen, and an inert gas or in a gas atmosphere under a reduced pressure, the light-emitting element emitted light similarly.
  • the light-emitting element 1 of the present embodiment has a structure similar to that of an inorganic EL display (ELD), but has a completely different configuration and mechanism.
  • a phosphor used in an inorganic EL display is a light-emitting body formed of a semiconductor such as ZnS : Mn 2+ and GaP : N as described in the background art section.
  • the phosphor particle in the embodiment may be either an insulator or a semiconductor, although an insulative phosphor particle is preferable.
  • a phosphor layer has a thickness of submicron to several ⁇ m.
  • the phosphor layer in the present embodiment has a porous structure with a thickness of several ⁇ m to several hundreds ⁇ m.
  • the light-emitting body has a porous structure.
  • the phosphor particles are packed so as to be in point contact with each other.
  • the phosphor particle powder that emits ultraviolet rays, which is used in current plasma display panels (PDPs), is used.
  • PDPs current plasma display panels
  • ZnS:Ag blue
  • ZnS:Cu gold
  • Au gold
  • Al green
  • Y 2 O 3 red
  • the light-emitting element of the present invention emits light by surface discharge that occurs in an avalanche manner due to electrons emitted from the electron-emitting body 119.
  • the light-emitting element is expected to emit light easily.
  • a colloidal silica solution is used to form the slurry of the phosphor particles 3.
  • an organic solvent it was confirmed that the same effect also was achieved by using an organic solvent. It is possible that a kneaded slurry containing 45 mass% of ⁇ -terpineol and 5 mass% of ethyl cellulose with respect to 50 mass% of the phosphor particle is formed, and the above-mentioned ceramic fiber board is immersed in the slurry, followed by heat treatment for degreasing.
  • the blue phosphor particle is used. However, it was found that the same result also was obtained by using a red or green phosphor particle. Further, mixed particles of blue, red, and green also provide the same result. Further, in the present embodiment, although an alternating electric field is applied between the first electrode 6 and the second electrode 7, a direct electric field may be applied.
  • the light-emitting element of the present embodiment emits light by surface discharge.
  • a conventional light-emitting element there is almost no need to use a thin film formation process for forming the phosphor layer, and neither a vacuum system nor a carrier intensifying layer is necessary. Therefore, the light-emitting element has a simple structure and is processed easily.
  • a light-emitting element including an electron-emitting body, a porous light-emitting body, and a pair of electrodes according to the present embodiment will be described with reference to FIGs. 31 and 32A to 32G.
  • the porous light-emitting body includes inorganic phosphor particles and is arranged adjacent to the electron-emitting body so as to be irradiated with electrons generated from the electron-emitting body, and a pair of the electrodes are arranged so that an electric field is applied to at least a part of the porous light-emitting body.
  • the electron-emitting body includes a cathode electrode, a gate electrode, and a carbon nanotube interposed between the two electrodes, and electrons emitted from the carbon nanotube by the application of a gate voltage between the cathode electrode and the gate electrode are irradiated to the porous light-emitting body, whereby the porous light-emitting body is allowed to emit light.
  • FIG. 31 is a cross-sectional view of the light-emitting element of the present embodiment.
  • Reference numeral 1 denotes a light-emitting element
  • 2 denotes a porous light-emitting body
  • 3 denotes a phosphor particle
  • 4 denotes an insulating layer
  • 6 denotes a first electrode
  • 7 denotes a second electrode
  • 111 denotes an anode electrode
  • 112 denotes a cathode electrode
  • 113 denotes a gate electrode
  • 116 denotes an insulating layer
  • 117 denotes a substrate
  • 127 denotes a carbon nanotube.
  • FIGs. 32A to 32G are views for explaining the manufacturing method of the light-emitting element shown in FIG. 31.
  • Au is deposited on a surface of the substrate 117 made of glass to form the cathode electrode 112 in the same manner as in Embodiment 16.
  • the substrate in the present embodiment may be made of ceramic instead of glass.
  • the insulating layer 116 is formed on the cathode electrode 112
  • the gate electrode 113 made ofAl is formed on the insulating layer 116 in the same manner as in Embodiment 16.
  • a kneaded paste containing 45 mass% of ⁇ -terpineol and 5 mass% of ethyl cellulose with respect to 50 mass% of carbon nanotube is dropped into a recess between the gate electrode 113 by screen printing, followed by drying.
  • the thus-obtained substrate is subjected to heat treatment at 400°C in an N 2 atmosphere, whereby the carbon nanotube is deposited in the recess as shown in FIG. 32E.
  • the carbon nanotube is subjected to orientation by adhering an adhesive film to a surface of the carbon nanotube and then peeling it off, whereby the vertically oriented carbon nanotube as shown in FIG.32F, which is favorable as an electron-emitting body, is formed.
  • the substrate on which the gate electrode is formed is coated with a photosensitive carbon nanotube paste and is exposed to light using a photomask to be developed, whereby the carbon nanotube is patterned.
  • a laser irradiation method may be used as a process for vertically orienting the carbon nanotube. Specifically, the paste containing carbon nanotube is used to form a carbon nanotube film, and then the film is irradiated with a laser, so that an organic resin contained in the carbon nanotube film is burned out, whereby the carbon nanotube can be exposed and raised on a surface of the film.
  • a ceramic board formed of inorganic fiber (an Al 2 O 3 -CaO-SiO 2 based ceramic fiber board with a thickness of about 1 mm and a void ratio of about 45%) supports phosphor particle powder.
  • an Ag electrode paste is baked to a thickness of 30 ⁇ m to form the first electrode 6 and the second electrode 7.
  • the ceramic fiber board thus obtained is attached to the electron-emitting body 119 by using colloidal silica, water glass, or an epoxy resin.
  • the porous light-emitting body 2 On a top surface of the porous light-emitting body 2, a glass (not shown) to which the transparent anode electrode (indium-tin oxide alloy (ITO), thickness: 15 ⁇ m) 111 is applied is laminated. Consequently, the light-emitting element 1 of the present embodiment as shown in FIG. 31 in which the porous light-emitting body 2 is formed on the electron-emitting body 119 and the electrodes are arranged at predetermined positions is obtained.
  • ITO indium-tin oxide alloy
  • a direct electric field of 750 V and 80 V is applied between the anode electrode 111 and the cathode electrode 112 and between the gate electrode 113 and the cathode electrode 112, respectively, in FIG. 31, so that electrons are emitted from the carbon nanotube in the direction of an arrow in the figure.
  • Electrons emitted due to electric charge transfer are doubled in an avalanche manner, and cause surface discharge in the porous light-emitting body 2. Surface discharge occurs continuously in a chain reaction, so that electric charge transfer is carried out in the vicinity of the phosphor particles. Electrons accelerated further collide with the luminescence center, so that the porous light-emitting body 2 is excited to emit light. At this time, ultraviolet rays and visible light also are generated, and the porous light-emitting body 2 also is excited to emit light by the ultraviolet rays.
  • the alternating electric field to be applied has its waveform changed from a sine wave or a sawtooth wave to a rectangular wave and has its frequency increased by several tens to thousands of Hz, electrons are emitted and surface discharge occurs more vigorously, resulting in increased emission brightness.
  • a current value during discharge is 0.1 mA or less. It was confirmed that light emission once started was sustained even when the voltage was decreased to 50% to 80% of the voltage applied initially.
  • the light-emitting element is driven in the atmosphere. However, it was confirmed that even in an atmosphere of oxygen, nitrogen, and an inert gas or in a gas atmosphere under a reduced pressure, the light-emitting element emitted light similarly.
  • the blue phosphor particle is used. However, it was found that the same result also was obtained by using a red or green phosphor particle. Further, mixed particles of blue, red, and green also provide the same result.
  • the light-emitting element of the present embodiment emits light by surface discharge.
  • a conventional light-emitting element there is almost no need to use a thin film formation process for forming the phosphor layer, and neither a vacuum system nor a carrier intensifying layer is necessary. Therefore, the light-emitting element has a simple structure and is processed easily.
  • a light-emitting element including an electron-emitting body, a porous light-emitting body, and a pair of electrodes according to the present embodiment will be described with reference to FIGs. 33 and 34A to 34C.
  • the porous light-emitting body includes inorganic phosphor particles and is arranged adjacent to the electron-emitting body so as to be irradiated with electrons generated from the electron-emitting body, and a pair of the electrodes are arranged so that an electric field is applied to at least a part of the porous light-emitting body.
  • the electron-emitting body is a surface-conduction-type electron-emitting element
  • a minute gap is provided in a metal oxide film
  • electrons generated from the gap by an electric field applied to the gap by the application of a voltage to an electrode provided on the metal oxide film beforehand are irradiated to the porous light-emitting body.
  • FIG. 33 is a cross-sectional view of the light-emitting element of the present embodiment.
  • Reference numeral 1 denotes a light-emitting element
  • 2 denotes a porous light-emitting body
  • 3 denotes a phosphor particle
  • 4 denotes an insulating layer
  • 6 denotes a first electrode
  • 7 denotes a second electrode
  • 117 denotes a substrate
  • 130 denotes a gap
  • 131 denotes a PdO ultrafine particle film
  • 132 denotes a Pt electrode.
  • FIGs. 34A to 34C are views for explaining the manufacturing method of the light-emitting element of the present embodiment shown in FIG. 33.
  • a Pt paste is subjected to patterning by screen printing on a surface of the ceramic substrate 17 so as to form the Pt electrode 132 with a small gap provided therebetween.
  • PdO ink coats the Pt electrode 132 so as to bridge between the Pt electrode 132 by ink-jet printing, followed by firing.
  • the PdO ultrafine particle film 131 is formed on the Pt electrode 132.
  • the thus-obtained substrate is subjected to an electrical treatment, so that as shown in FIG. 34C, the PdO ultrafine particle film 31 is cracked to form the minute gap 30 of about 10 nm.
  • the electron-emitting body of the present embodiment is formed without using a photolithography process and with a relatively smaller number of processes, and thus it is very excellent in economical efficiency and in view of achieving a large-screen display.
  • a ceramic board formed of inorganic fiber (an Al 2 O 3 -CaO-SiO 2 based ceramic fiber board with a thickness of about 1 mm and a void ratio of about 45%) supports phosphor particle powder.
  • an Ag electrode paste is baked to a thickness of 30 ⁇ m to form the first electrode 6 and the second electrode 7, respectively.
  • the ceramic fiber board thus obtained is attached to the electron-emitting body 119 by using colloidal silica, water glass, or an epoxy resin.
  • the light-emitting element 1 of the present embodiment as shown in FIG. 313 in which the porous light-emitting body 2 is provided on the electron-emitting body 119 and the electrodes are arranged at predetermined positions is obtained.
  • a DC voltage of 12 to 16 V is applied between the two Pt electrodes 132 shown in FIG. 33, so that electrons are emitted from one of the electrodes via the slit of 10 nm by a tunnel effect in the direction of an arrow in the figure and are irradiated to the porous light-emitting body 2.
  • Electrons emitted due to electric charge transfer are doubled in an avalanche manner, and cause surface discharge in the porous light-emitting body 2. Surface discharge occurs continuously in a chain reaction, so that electric charge transfer is carried out in the vicinity of the phosphor particles. Electrons accelerated further collide with the luminescence center, so that the porous light-emitting body 2 is excited to emit light. At this time, ultraviolet rays and visible light also are generated, and the porous light-emitting body 2 also is excited to emit light by the ultraviolet rays.
  • the alternating electric field to be applied has its waveform changed from a sine wave or a sawtooth wave to a rectangular wave and has its frequency increased by several tens to thousands of Hz, electrons are emitted and surface discharge occurs more vigorously, resulting in increased emission brightness.
  • a current value during discharge is 0.1 mA or less. It was confirmed that light emission once started was sustained even when the voltage was decreased to 50% to 80% of the voltage applied initially.
  • the light-emitting element is driven in the atmosphere. However, it was confirmed that even in an atmosphere of oxygen, nitrogen, and an inert gas or in a gas atmosphere under a reduced pressure, the light-emitting element emitted light similarly.
  • the phosphor particle powder that emits ultraviolet rays, which is used in current plasma display panels (PDPs), is used.
  • PDPs current plasma display panels
  • ZnS:Ag blue
  • ZnS:Cu gold
  • Au gold
  • Al green
  • Y 2 O 3 red
  • the light-emitting element of the present invention emits light by surface discharge that occurs in an avalanche manner due to electrons emitted from the electron-emitting body 119.
  • the light-emitting element is expected to emit light easily.
  • the blue phosphor particle is used. However, it was found that the same result also was obtained by using a red or green phosphor particle. Further, mixed particles of blue, red, and green also provide the same result.
  • the light-emitting element of the present embodiment emits light by surface discharge.
  • a conventional light-emitting element there is almost no need to use a thin film formation process for forming the phosphor layer, and neither a vacuum system nor a carrier intensifying layer is necessary. Therefore, the light-emitting element has a simple structure and is processed easily.
  • an electron-emitting body instead of using the electron-emitting body as described in the present embodiment, it is also possible to use a similar electron-emitting body in which an insulating layer is sandwiched between two electrodes and electrons are emitted by the application of an electric field between the electrodes.
  • an upper electrode is formed of an Ir-Pt-Au alloy
  • a cathode electrode is formed of Al
  • the insulating layer is formed of Al 2 O 3 .
  • the insulating layer is sandwiched between the two electrodes, and electrons are emitted from the upper electrode when an electric field is applied between the electrodes.
  • Such an electron-emitting body can be used to manufacture the light-emitting element to irradiate the porous light-emitting body with electrons.
  • a light-emitting element including an electron-emitting body, a porous light-emitting body, and a pair of electrodes according to the present embodiment will be described with reference to FIGs. 35 and 36A to 36D.
  • the porous light-emitting body includes inorganic phosphor particles and is arranged adjacent to the electron-emitting body so as to be irradiated with electrons generated from the electron-emitting body, and a pair of the electrodes are arranged so that an electric field is applied to at least a part of the porous light-emitting body.
  • the electron-emitting body includes a polysilicon thin film, a silicon microcrystal, and an oxide film formed on a surface of the silicon microcrystal, and electrons emitted by the application of a voltage to the electron-emitting body are irradiated to the porous light-emitting body, whereby the porous light-emitting body is allowed to emit light.
  • FIG. 35 is a cross-sectional view of the light-emitting element of the present embodiment.
  • Reference numeral 1 denotes a light-emitting element
  • 2 denotes a porous light-emitting body
  • 3 denotes a phosphor particle
  • 4 denotes an insulating layer
  • 6 denotes a first electrode
  • 7 denotes a second electrode
  • 112 denotes a cathode electrode
  • 119 denotes an electron-emitting body
  • 141 denotes a metal thin film electrode
  • 145 denotes polysilicon
  • 147 denotes a silicon microcrystal.
  • FIGs. 36A to 36D are views for explaining the manufacturing method of the light-emitting element shown in FIG. 35. As shown in FIG.
  • the polysilicon 145 formed on the cathode electrode 112 is made porous to form the nanosilicon microcrystal 147.
  • the substrate is immersed in a mixed solution of hydrofluoric acid and ethyl alcohol, and a voltage is applied between the substrate as a positive electrode and, as a counter electrode, Pt as a negative electrode, whereby the silicon microcrystal is formed on the cathode electrode 112.
  • the substrate 143 is washed and then is immersed in a sulphuric acid solution.
  • a voltage is applied between the substrate as a positive electrode and Pt as a negative electrode as above, so that surfaces of both the polysilicon 145 and the silicon microcrystal are oxidized.
  • the metal thin film electrode 141 formed of an Au alloy, an Ag alloy, or the like is provided by sputtering, followed by photoetching for patterning. As a result the electron-emitting body 119 is obtained.
  • the manufacturing method of the electron-emitting body of the present embodiment requires a relatively small number of processes and can include a wet process, and therefore is excellent in economical efficiency.
  • a ceramic board formed of inorganic fiber (an Al 2 O 3 -CaO-SiO 2 based ceramic fiber board with a thickness of about 1 mm and a void ratio of about 45%) supports phosphor particle powder.
  • an Ag electrode paste is baked to a thickness of 30 ⁇ m to form the first electrode 6 and the second electrode 7, respectively.
  • the ceramic fiber board thus obtained is attached to the electron-emitting body 119 by using colloidal silica, water glass, or an epoxy resin.
  • the light emitting action of the light-emitting element 1 will be described.
  • a direct electric field of 15 to 20 V is applied between the metal thin film electrode 141 and the cathode electrode 112 shown in FIG. 35, so that electrons from the cathode electrode tunnel through the silicon microcrystal, are accelerated by the oxide film on its surface, and are emitted into the porous light-emitting body.
  • Electrons emitted due to electric charge transfer are doubled in an avalanche manner, and cause surface discharge in the porous light-emitting body 2. Surface discharge occurs continuously in a chain reaction, so that electric charge transfer is carried out in the vicinity of the phosphor particles. Electrons accelerated further collide with the luminescence center, so that the porous light-emitting body 2 is excited to emit light. At this time, ultraviolet rays and visible light also are generated, and the porous light-emitting body 2 also is excited to emit light by the ultraviolet rays.
  • the alternating electric field to be applied has its waveform changed from a sine wave or a sawtooth wave to a rectangular wave and has its frequency increased by several tens to thousands of Hz, electrons are emitted and surface discharge occurs more vigorously, resulting in increased emission brightness.
  • an alternating electric field of about 0.5 to 1.0 kV/mm is applied in a thickness direction of the porous light-emitting body 2 by using an AC power supply, electric charge transfer is carried out and surface discharge occurs, followed by light emission.
  • a higher electric field is applied, the generation of electrons is accelerated, and when an excessively low electric field is applied, the generation of electrons is insufficient.
  • a current value during discharge is 0.1 mA or less. It was confirmed that light emission once started was sustained even when the voltage was decreased to 50% to 80% of the voltage applied initially.
  • the light-emitting element is driven in the atmosphere. However, it was confirmed that even in an atmosphere of oxygen, nitrogen, and an inert gas or in a gas atmosphere under a reduced pressure, the light-emitting element emitted light similarly.
  • the blue phosphor particle is used. However, it was found that the same result also was obtained by using a red or green phosphor particle. Further, mixed particles of blue, red, and green also provide the same result.
  • the light-emitting element of the present embodiment emits light by surface discharge.
  • a conventional light-emitting element there is almost no need to use a thin film formation process for forming the phosphor layer, and neither a vacuum system nor a carrier intensifying layer is necessary. Therefore, the light-emitting element has a simple structure and is processed easily.
  • the electron-emitting body of the present embodiment is formed of a whisker emitter instead of the carbon nanotube as mentioned above.
  • FIGs. 37A to 37C are views for explaining the manufacturing method of the electron-emitting body of the present embodiment.
  • Reference numeral 112 denotes a cathode electrode
  • 113 denotes a gate electrode
  • 116 denotes an insulating layer
  • 117 denotes a substrate
  • 155 denotes an organic metal complex gas
  • 157 denotes a whisker emitter.
  • Au is deposited on a surface of the substrate 117 formed of glass to form the cathode electrode 112, the insulating layer 116 is formed thereon, and the gate electrode 113 is formed on the insulating layer 116 in the same manner as in Embodiment 19. Then, as shown in FIG.
  • the whisker emitter is formed by a CVD method. Specifically, a large amount of Al : Zn organic metal complex gas 155 is showered toward the cathode electrode. At this time, when a certain amount or more of gas is showered, a thermally-oxidized Al : ZnO film grows in a vertical direction. Further, as the source gas is increased, a front end of the film becomes sharp to a level of several nm. In this manner, the Al : ZnO whisker is patterned and oriented vertically in a self-aligned manner. The film is formed by paying attention to a source gas input, a film forming temperature, and a film formation time. As a result, the electron-emitting body having the Al : ZnO whisker emitter 157 as shown in FIG. 37C is obtained.
  • the porous light-emitting body is manufactured by allowing a ceramic board formed of inorganic fiber (an Al 2 O 3 -CaO-SiO 2 based ceramic fiber board with a thickness of about 1 mm and a void ratio of about 45%) to support phosphor particle powder.
  • Predetermined electrodes are arranged on the porous light-emitting body, and the thus-obtained porous light-emitting body is laminated on the above-mentioned electron-emitting body, whereby the light-emitting element (not shown) is obtained.
  • a direct electric field of 850 V and 80 V is applied between an anode electrode and the cathode electrode and between the gate electrode and the cathode electrode, respectively, so that electrons are emitted from the whisker emitter.
  • Electrons emitted due to electric charge transfer are doubled in an avalanche manner, and cause surface discharge in the porous light-emitting body. Surface discharge occurs continuously in a chain reaction, so that electric charge transfer is carried out in the vicinity of the phosphor particles. Electrons accelerated further collide with the luminescence center, so that the porous light-emitting body is excited to emit light. At this time, ultraviolet rays and visible light also are generated, and the porous light-emitting body 2 also is excited to emit light by the ultraviolet rays.
  • the alternating electric field to be applied has its waveform changed from a sine wave or a sawtooth wave to a rectangular wave and has its frequency increased by several tens to thousands of Hz, electrons are emitted and surface discharge occurs more vigorously, resulting in increased emission brightness.
  • the light-emitting element is driven in the atmosphere. However, it was confirmed that even in an atmosphere of oxygen, nitrogen, and an inert gas or in a gas atmosphere under a reduced pressure, the light-emitting element emitted light similarly.
  • the blue phosphor particle is used. However, it was found that the same result also was obtained by using a red or green phosphor particle. Further, mixed particles of blue, red, and green also provide the same result.
  • the light-emitting element of the present embodiment emits light by surface discharge.
  • a conventional light-emitting element there is almost no need to use a thin film formation process for forming the phosphor layer, and neither a vacuum system nor a carrier intensifying layer is necessary. Therefore, the light-emitting element has a simple structure and is processed easily.
  • silicon carbide or a diamond thin film may be used instead of the whisker emitter.
  • electrons can be emitted from the material by the application of a gate voltage between the cathode electrode and the gate electrode and irradiated to the porous light-emitting body.
  • a light-emitting element including an electron-emitting body, a porous light-emitting body, and a pair of electrodes will be described with reference to FIGs. 38 to 40.
  • the description is directed to the pair of electrodes provided to apply an electric field to the porous light-emitting body.
  • FIGs. 38 to 40 are cross-sectional views of the porous light-emitting body constituting a part of the light-emitting element.
  • Reference numeral 2 denotes a porous light-emitting body
  • 3 denotes a phosphor particle
  • 4 denotes an insulating layer
  • 6 denotes a first electrode
  • 7 denotes a second electrode.
  • the blue phosphor particle 3 coated with the insulating layer 4 of an insulative inorganic substance of MgO is used as in Embodiment 16.
  • the phosphor particle is added to an Mg precursor complex solution, stirred for a long time, and then taken out from the solution, followed by drying.
  • the phosphor particle is subjected to heat treatment at 400°C to 600°C in the atmosphere, whereby a uniform coating layer of MgO, i.e., the insulating layer, is formed on a surface of the phosphor particle.
  • a uniform coating layer of MgO i.e., the insulating layer
  • 50 mass% of the phosphor particle 3 coated with the insulating layer 4 and 50 mass% of a colloidal silica solution are mixed to form a slurry.
  • a ceramic board formed of inorganic fiber (an Al 2 O 3 -CaO-SiO 2 based ceramic fiber board with a thickness of about 1 mm and a void ratio of about 45%) is immersed in the slurry, followed by drying at 120°C to 150°C for 10 to 30 minutes.
  • the ceramic board supports phosphor particle powder.
  • an Ag electrode paste is baked to a thickness of 30 ⁇ m to form the first electrode 6 and the second electrode 7.
  • the ceramic fiber board thus obtained is attached to the electron-emitting body by using colloidal silica, water glass, or an epoxy resin, whereby the light-emitting element (not shown) of the present invention is obtained.
  • the first electrode 6 and the second electrode 7 are formed on a top surface and a bottom surface, respectively, of the porous light-emitting body so as to be opposed to each other.
  • these electrodes may be formed on both the top surface and the bottom surface in a diagonally crossed manner.
  • the porous light-emitting body When the porous light-emitting body has an apparent porosity of less than 10%, surface discharge occurs only on a surface of the phosphor, resulting in decreased luminous efficiency. Therefore, it is desirable that the porous light-emitting body has a porous structure with an apparent porosity of not less than 10%. On the other hand, when the porosity is excessively high due to too large pores of the phosphors, it is expected that the luminous efficiency is decreased or that surface discharge is less likely to occur. On this account, ideally, the apparent porosity is preferably in a range of not less than 10% to less than 100%.
  • an Ag electrode paste is baked to a thickness of 30 ⁇ m to form the first electrode 6 and the second electrode 7.
  • 50 mass% of the phosphor particle 3 coated with the insulating layer 4 and 50 mass% of a colloidal silica solution are mixed to form a slurry, and the slurry is applied to the surface of the porous light-emitting body on which the electrodes are formed, followed by drying at 120°C to 150°C for 10 to 30 minutes.
  • the porous light-emitting body in which both the first electrode 6 and the second electrode 7 are buried is obtained.
  • the insulating layer of MgO may be formed on the surface of the phosphor particle in the following manner. Initially, Mg(OC 2 H 5 ) 2 powder (1 molar ratio) as metal alkoxide is mixed well by stirring in a solution of CH 3 COOH (10 molar ratio), H 2 O (50 molar ratio), and C 2 H 5 OH (50 molar ratio) at room temperature, whereby a substantially transparent sol/gel solution is prepared.
  • Phosphor particles (2 molar ratio), such as BaMgAl 10 O 17 :Eu 2+ (blue), Zn 2 SiO 4 :Mn 2+ (green), and YBO 3 :Eu 3+ (red), with an average particle diameter of 2 to 3 ⁇ m are mixed little by little by stirring into the sol/gel solution. This operation is performed continuously for 1 day, and then the mixed solution undergoes centrifugal separation so as to take powder therefrom to a tray made of ceramic, which is allowed to dry at 150°C all day and night.
  • the dried powder is calcined in the air at 400°C to 600°C for 2 to 5 hours, so that the uniform insulating layer of MgO is formed on the surface of the phosphor particle.
  • the thickness of the insulating layer is 0.1 to 2.0 ⁇ m.
  • the coating of the insulating layer can be provided by immersing the phosphor particle in a metal alkoxide solution, by using a metal complex solution as mentioned above, or by deposition, sputtering, CVD, and the like.
  • Y 2 O 3 Li 2 O, MgO, CaO, BaO, SrO, Al 2 O 3 , SiO 2 , MgTiO 3 , CaTiO 3 , BaTiO 3 , SrTiO 3 , ZrO 2 , TiO 2 , B 2 O 3 , and the like are known. It is desirable to use at least one of these materials to form the insulating layer.
  • the phosphor particle when the insulating layer is formed by a vapor phase method, it is desirable that the phosphor particle is subjected to a pretreatment in a nitrogen atmosphere at 200°C to 500°C for about 1 to 5 hours.
  • phosphor particles contain a large amount of absorbed water and water of crystallization, and it is not preferable to form the insulating layer on the phosphor particles in such a state because this has an effect on lifetime properties such as a deterioration of brightness and a shift in emission spectrum.
  • the thickness of the insulating layer is set to about 0.1 to 2.0 ⁇ m. However, the thickness may be determined in view of an average particle diameter of the phosphor particle and the occurrence of surface discharge. In the case of an average particle diameter on a submicron order, it is considered that a very thin coating layer is required to be formed.
  • the relationship between the average particle diameter of the phosphor particle and the thickness of the insulating layer is preferably in the proportion of 1 part to 1/10 to 1/500.
  • each phosphor particle is coated with the insulating layer of a metal oxide. Practically, however, 2 or 3 phosphor particles are coated in a flocculated state. Even when the phosphor particles are coated in such a somewhat flocculated state, there is substantially no effect on light emission.
  • the light-emitting element of the present invention is manufactured by using the porous light-emitting body thus obtained. As a result, it was confirmed that the light-emitting element exhibited a high brightness, a high contrast, a high recognition capability, and a high reliability.
  • FIG. 41 shows a schematic cross-sectional view of the porous light-emitting body thus obtained.
  • a mixture of the phosphor particles 3 and the insulative fibers 18 may be used simply.
  • FIG. 42 is a schematic cross-sectional view of the porous light-emitting body formed of the mixture of the phosphor particles 3 and the insulative fibers 18.
  • FIG. 43 is an exploded perspective view of main portions of the field emission display of the present embodiment.
  • FIG. 44 is a cross-sectional view of an array of light-emitting elements using the Spindt-type emitter according to the present embodiment.
  • reference numeral 2 denotes a porous light-emitting body
  • 119 denotes an electron-emitting body
  • 170 denotes a field emission display
  • 171 denotes a gate line
  • 172 denotes a cathode line
  • 173 denotes an anode substrate
  • 174 denotes a cathode substrate.
  • reference numeral 1 denotes a light-emitting element
  • 2 denotes a porous light-emitting body
  • 3 denotes a phosphor particle
  • 4 denotes an insulating layer
  • 100 denotes a Spindt-type emitter
  • 111 denotes an anode electrode
  • 112 denotes a cathode electrode
  • 113 denotes a gate electrode
  • 116 denotes an insulator
  • 117 denotes a substrate
  • 175 denotes a spacer.
  • the anode substrate 173 with the porous light-emitting bodies 2 is laminated on the cathode substrate 174 mounted with the electron-emitting bodies 119 so as to be opposed thereto.
  • the cathode substrate 174 On the cathode substrate 174, two-layer wirings of the gate lines 171 and the cathode lines 172 that are orthogonal to each other are formed, and the electron-emitting body 119 is formed at a point of intersection of these lines. This allows the field emission display 170 of the present embodiment to display a two-dimensional image on a phosphor screen without deflecting an electron beam as in a CRT.
  • the electron-emitting body 119 using the Spindt-type emitter 100 includes the cone-shaped Spindt-type emitter 100 and the gate electrode 113 formed so as to surround the Spindt-type emitter 100 for the application of a voltage for drawing electrons.
  • a positive potential is applied to the gate, and a negative potential is applied to the emitter.
  • a high electric field is concentrated on a front end portion of the cone-shaped emitter, and electrons are emitted therefrom toward the porous light-emitting body 2.
  • Mo Spindt-type emitter the application of a voltage of 15 to 80 V causes electrons to be emitted.
  • a plurality of emitters are provided for each pixel, so that a high level of redundancy can be ensured with respect to an operating state of the emitters. Consequently, current fluctuations specific to this type of element are averaged statistically, and thus each pixel is allowed to emit light stably.
  • the field emission display can be driven in a so-called simple matrix.
  • One line is displayed at a time by applying a negative data voltage to the emitter line 172 while applying a positive scan pulse to the gate line 171.
  • a two-dimensional image can be displayed.
  • the field emission display can be driven more actively.
  • FIG. 44 shows a cross section of an exemplary light-emitting element in which a plurality of the Spindt-type emitters 100 are formed and the porous light-emitting bodies 2 are laminated so as to correspond to the respective emitters.
  • the spacer 175 between the porous light-emitting bodies 2 it is desirable to form the spacer 175 between the porous light-emitting bodies 2 so as to avoid crosstalk during light emission.
  • the Spindt-type emitter 100 is used as the electron-emitting body 119.
  • the present invention is not necessarily limited thereto, and any devices having a function of emitting electrons may be combined with the porous light-emitting body of the present invention to manufacture the field emission display.
  • FIGs. 45A to 45C are cross-sectional views of a light-emitting element of the present embodiment.
  • reference numeral 1 denotes a light-emitting element
  • 2 denotes a porous light-emitting layer
  • 3 denotes a phosphor particle
  • 4 denotes an insulating layer
  • 5 denotes a substrate
  • 6 denotes a first electrode
  • 7 denotes a second electrode
  • 8 denotes a transparent substrate
  • 9 denotes a gas layer
  • 10 denotes a dielectric layer
  • 11 denotes a partition wall.
  • the light-emitting element in FIG. 45A is manufactured as follows. Initially, on one side of the sintered dielectric 10 with a thickness of 0.3 to 1.0 mm, an Ag paste is baked to a thickness of 30 ⁇ m to form the first electrode 6 of a predetermined shape. Then, the side of the dielectric on which the first electrode is formed is adhered onto the substrate 5 made of glass or ceramic.
  • the dielectrics as described in Embodiment 1 are available.
  • the phosphor particles 3, each being coated with the insulating layer 4 made of a metal oxide such as MgO, are prepared.
  • an inorganic compound such as BaMgAl 10 O 17 :Eu 2+ (blue), Zn 2 SiO 4 :Mn 2+ (green), and YBO 3 :Eu 3+ (red), with an average particle diameter of 2 to 3 ⁇ m can be used.
  • the phosphor particle 3 coated with the insulating layer 4 of MgO is mixed with 5 mass% of polyvinyl alcohol to be granulated, and then the granules are molded in a plate shape under a pressure of about 50 MPa by using a molding die.
  • the thus-obtained molded granules are subjected to heat treatment at 450°C to 1200°C for 2 to 5 hours in a nitrogen atmosphere, whereby the plate-shaped porous light-emitting body 2 is manufactured.
  • the porous light-emitting body When the porous light-emitting body has an apparent porosity of less than 10%, the luminous efficiency is decreased for the following reason. That is, when electrons collide with the porous light-emitting layer, although light is emitted on a surface of the porous light-emitting layer, electrons are not injected into the light-emitting layer, and thus substantially no light is emitted inside the layer. To avoid this, in order to allow electrons generated due to discharge to be injected smoothly into the porous light-emitting layer, it is desirable that the porous light-emitting body of the present embodiment has a porous structure with an apparent porosity of not less than 10%.
  • the porous light-emitting body has an excessively high apparent porosity, the luminous efficiency is decreased or surface discharge is less likely to occur inside the porous light-emitting layer.
  • the apparent porosity is preferably in a range of not less than 10% to less than 100%, and in particular in a range of 50% to less than 100%.
  • the plate-shaped porous light-emitting body 2 thus obtained is attached to the dielectric layer 10 by using a glass paste.
  • the glass paste is screen-printed on the porous light-emitting layer at its both ends, so that the porous light-emitting layer is adhered thereto, followed by heat treatment at 580°C.
  • the porous light-emitting layer can be adhered to the dielectric layer 10 with the gas layer interposed therebetween.
  • the porous light-emitting layer is covered with the transparent substrate 8 such as a glass plate on which the second electrode 7 made of ITO (indium-tin oxide alloy) is formed beforehand so as to be opposed to the porous light-emitting layer, whereby the light-emitting element 1 shown in FIG. 45A is obtained.
  • the transparent substrate 8 is attached by heat treatment using a glass paste, colloidal silica, water glass, a resin, or the like, so that a slight gap for gas is provided between the porous light-emitting layer 2 and the second electrode 7. Consequently, as shown in FIG. 45A, the both end portions of the porous light-emitting layer are adhered by a glass paste or the like that functions as the partition wall 11 in a state where the gas layers are provided on and under the porous light-emitting layer.
  • the gas layers provided both on and under the porous light-emitting layer i.e., the gas layer interposed between the porous light-emitting layer 2 and the dielectric layer 10 and the gas layer interposed between the porous light-emitting layer and the second electrode, which are a characteristic of the present embodiment, have a thickness preferably in a range of 20 to 250 ⁇ m, and most preferably in a range of 30 to 220 ⁇ m.
  • the thickness of the gas layer may be smaller than the above range, and there is no practical problem as long as the thickness is not less than a mean free path of gas.
  • the gas layer has a very small thickness, it may be somewhat difficult to control the thickness in the process of manufacturing the light-emitting element.
  • the gas layers provided on and under the porous light-emitting layer according to the present embodiment have the same thickness.
  • the thickness of each of the gas layers is set to be slightly smaller than that of the gas layer provided only on one side of the light-emitting layer as in FIG. 1.
  • the thickness of the gas layers is larger, a relatively high voltage is required to be applied for the occurrence of discharge, which is not preferable for the reason of economical efficiency.
  • the present embodiment is characterized in that the gas layers are provided on and under the porous light-emitting layer.
  • an AC electric field is applied between a pair of the first electrode and the second electrode, discharge occurs simultaneously in both the gas layers, so that electrons are emitted from above and below the porous light-emitting layer to be injected into the light-emitting layer efficiently.
  • the AC electric field to be applied is increased gradually, and when a voltage not less than the dielectric breakdown voltage is applied to the gas layers, discharge occurs. Accordingly, electrons are doubled in the gas layers and collide with the porous light-emitting body to excite the luminescence center thereof, so that the porous light-emitting layer emits light.
  • the gas layers function as an electron supply source, and generated electrons are injected from above and below the porous light-emitting layer and pass through the light-emitting layer in an avalanche manner while causing surface discharge throughout the layer.
  • Surface discharge occurs continuously during the application of an electric field. Electrons generated in an avalanche manner during the application of an electric field collide with the luminescence center of the phosphors, so that the phosphor particles 3 are excited to emit light. As described above, electrons are injected efficiently from above and below the porous light-emitting layer.
  • the light-emitting layer having a porous structure according to the present embodiment wholly emits light thoroughly, uniformly, and efficiently, resulting in a remarkably increased brightness.
  • the light-emitting element including the gas layers, the porous light-emitting layer in contact with the gas layers, and at least a pair of the electrodes for applying an electric field to the gas layers and the porous light-emitting layer.
  • the dielectric layer and the first electrode of a pair of the electrodes for applying an electric field are arranged on one surface of the porous light-emitting layer via the gas layer, and the second electrode of a pair of the electrodes is arranged on the other surface of the porous light-emitting layer where the dielectric layer and the first electrode are not arranged, via the gas layer.
  • the points to note in particular during the heat treatment process for forming the porous light-emitting layer include heat treatment temperature and atmosphere.
  • the heat treatment is performed in a nitrogen atmosphere at a temperature in a range of 450°C to 1200°C, a valence of the doped rare earth element in the phosphor is not changed.
  • the heat treatment atmosphere it is preferable to perform the heat treatment in a nitrogen atmosphere so as to avoid an effect on the valence of the doped rare earth element in the phosphor particle.
  • the thickness of the insulating layer is set to about 0.1 to 2.0 ⁇ m.
  • the thickness may be determined in view of an average particle diameter of the phosphor particle and efficiency of surface discharge occurrence.
  • the phosphor with an average particle diameter on a submicron order has a relatively thin coating.
  • a large thickness of the insulating layer is not preferable since it may result in a shift in emission spectrum, a deterioration in brightness, and the like.
  • an AC electric field is applied between the first electrode 6 and the second electrode 7.
  • the AC electric field to be applied is increased gradually, and when a voltage not less than the dielectric breakdown voltage is applied to the gas layers, discharge occurs. Accordingly, electrons are doubled in the gas layers and collide with the porous light-emitting body to excite the luminescence center thereof, so that the light-emitting layer emits light.
  • the gas layers function as an electron supply source, and in the present embodiment, generated electrons are injected from above and below the porous light-emitting layer and pass through the light-emitting layer in an avalanche manner while causing surface discharge throughout the porous light-emitting layer.
  • electrons are injected from above and below the porous light-emitting layer. Therefore, as compared with the light-emitting element in which electrons are injected from only one side of the light-emitting layer as described in Embodiment 1, the porous light-emitting layer wholly emits light thoroughly, uniformly, and efficiently, resulting in a remarkably increased brightness.
  • the porous light-emitting body having an apparent porosity in a range of not less than 10% to less than 100% is used.
  • a usual light-emitting layer without a porous structure light is emitted on its surface but is hardly emitted inside the layer.
  • the porous light-emitting layer of the present embodiment light is emitted not only on its surface but also inside the light-emitting layer, resulting in considerably favorable luminous efficiency.
  • the porous structure allows electrons generated due to discharge to be injected smoothly into the layer, so that surface discharge occurs throughout the layer, and the layer wholly emits light with a high brightness.
  • the porous light-emitting body used in the present embodiment has a porous structure with an apparent porosity of not less than 10%.
  • the apparent porosity is desirably in a range of not less than 10% to less than 100%, and most preferably in a range of 50% to less than 100%.
  • the generation of electrons is accelerated, and when a lower electric field is applied, the generation thereof is suppressed.
  • the gas present in the gas layer is air
  • at least a voltage of about 0.3 kV/mm which is a dielectric breakdown voltage of air, is required to be applied.
  • a current value during discharge is 0.1 mA or less. It was confirmed that light emission once started was sustained even when the voltage was decreased to about 50% to 80% of the voltage applied initially, and that a high brightness, a high contrast, a high recognition capability, and a high reliability were ensured in light emission of the phosphor particles of each of the three colors.
  • the light-emitting element is driven in the atmosphere. However, it was confirmed that even in an atmosphere of a rare gas or in a gas atmosphere in which pressure is applied or a negative pressure is formed, the light-emitting element emitted light similarly.
  • the porous light-emitting layer is formed by a thick film process or the like.
  • the light-emitting element has a simple structure and is manufactured and processed easily. Further, electrons generated due to discharge can collide with the porous light-emitting layer from both sides thereof, and due to the porous structure of the light-emitting body, the colliding electrons are allowed to be injected smoothly into the light-emitting layer while causing surface discharge, resulting in light emission with a very high brightness.
  • the porous light-emitting layer of the present embodiment wholly emits light thoroughly, resulting in a high brightness. Further, the luminous efficiency is considerably favorable as compared with that achieved by phosphors that emit ultraviolet rays as in plasma display panels. Further, it is possible to provide a light-emitting element that is to be driven with relatively low power consumption when being used in a large-screen display. Since the partition walls are provided as discharge separation means at both ends of the porous light-emitting layer, crosstalk during light emission can be avoided easily.
  • FIG. 45C shows the same light-emitting element as in FIGs. 45A and 45B except that the dielectric layer 10 interposed between the porous light-emitting layer 2 and the first electrode 6 is not provided.
  • the light-emitting element in FIG. 45C is manufactured as follows. Initially, on one side of the substrate 5 made of glass or ceramic, an Ag paste is baked to a thickness of 30 ⁇ m to form the first electrode 6 into a predetermined shape.
  • the phosphor particles 3, each being coated with the insulating layer 4 made of a metal oxide such as MgO, are prepared.
  • an inorganic compound such as BaMgAl 10 O 17 :Eu 2+ (blue), Zn 2 SiO 4 :Mn 2+ (green), and YBO 3 :Eu 3+ (red), with an average particle diameter of 2 to 3 ⁇ m can be used.
  • the phosphor particle 3 coated with the insulating layer 4 of MgO is mixed with 5 mass% of polyvinyl alcohol to be granulated, and then the granules are molded in a plate shape under a pressure of about 50 MPa by using a molding die.
  • the thus-obtained molded granules are subjected to heat treatment at 450°C to 1200°C for 2 to 5 hours in a nitrogen atmosphere, whereby the plate-shaped porous light-emitting body 2 is manufactured.
  • Both ends of the plate-shaped porous light-emitting body 2 thus obtained are attached to an electrode side of the substrate 5 by using a glass paste.
  • the glass paste is screen-printed, so that the porous light-emitting layer is adhered, followed by heat treatment at 580°C.
  • the porous light-emitting layer 2 is fixed with a slight gap formed of the gas layer provided between the porous light-emitting layer 2 and the first electrode.
  • the gas layer provided between the porous light-emitting layer 2 and the first electrode 6 preferably has a thickness in a range of 20 to 250 ⁇ m, and in particular in a range of 30 to 220 ⁇ m.
  • the thickness of the gas layer may be smaller than the above range, and there is no problem as long as the thickness is larger than a mean free path of gas.
  • the porous light-emitting layer is covered with the transparent substrate 8 such as a glass plate on which the second electrode 7 made of ITO (indium-tin oxide alloy) is formed beforehand so as to be opposed to the porous light-emitting layer, whereby the light-emitting element 1 of the present embodiment as shown in FIG. 45C is obtained.
  • the transparent substrate 8 is attached by heat treatment using colloidal silica, water glass, a resin, or the like, so that a slight gap formed of the gas layer is provided between the porous light-emitting layer 2 and the second electrode 7.
  • the width of the gap between the porous light-emitting layer 2 and the second electrode 7 is not necessarily required to be the same as that of the gap between the porous light-emitting layer and the first electrode. They may be set to be substantially the same.
  • the present embodiment is characterized in that the slight gaps are provided between the porous light-emitting layer and the first and second electrodes, respectively, provided on both sides of the porous light-emitting layer.
  • This configuration allows the gas layers formed of a rare gas, atmospheric air, oxygen, nitrogen, or a mixed gas thereof to be interposed between the porous light-emitting layer and a pair of the electrodes, respectively.
  • An AC electric field is applied between a pair of the electrodes of the light-emitting element, and when a voltage not less than the dielectric breakdown voltage is applied to the gas layers, discharge occurs.
  • the gas layers function as an electron supply source, and generated electrons collide with the light-emitting layer, are injected into the layer, and pass through the light-emitting layer in an avalanche manner while causing surface discharge throughout the layer. Surface discharge occurs continuously during the application of an electric field. Electrons generated in an avalanche manner collide with the luminescence center of the phosphors, so that the phosphor particles 3 are excited to emit light.
  • the light-emitting layer wholly emits light uniformly and efficiently with an increased brightness.
  • the phosphor particle 3 coated with the insulating layer 4 of MgO is used.
  • MgO has a high specific resistance (10 9 ⁇ •cm or more) and surface discharge can occur efficiently.
  • An insulating layer with a low specific resistance is not preferable since surface discharge is less likely to occur, and a short circuit may occur in some cases.
  • the insulating layer at least one selected from Y 2 O 3 , Li 2 O, CaO, BaO, SrO, Al 2 O 3 , SiO 2 , and ZrO 2 can be used as well as MgO.
  • These oxides are stable substances with an extremely low standard free energy of formation ⁇ G f 0 (e.g., - 100 kcal/mol or less at room temperature).
  • the insulating layer of these substances is favorable since it has a high specific resistance and is less likely to be reduced.
  • this layer also serves as an excellent protective coating for suppressing reduction and deterioration of the phosphor particle due to electrons, resulting in increased durability of the phosphor.
  • the insulating layer can be formed by chemisorption or physical adsorption using a CVD method, a sputtering method, a deposition method, a laser method, a shearing stress method, and the like. It is desirable for the insulating layer to be homogeneous and uniform so as not to be peeled off. To this end, it is important, in forming the insulating layer, to immerse the phosphor particle in a weak acid solution of acetic acid, oxalic acid, citric acid, or the like so as to wash impurities attached to a surface of the phosphor particle.
  • the phosphor particle is subjected to a pretreatment in a nitrogen atmosphere at 200°C to 500°C for about 1 to 5 hours before the formation of the insulating layer.
  • the reason for this is as follows.
  • a usual phosphor particle contains a large amount of adsorbed water and water of crystallization, and the formation of the insulating layer on the phosphor particle in such a state exerts an undesirable effect on the lifetime property, such as a deterioration in brightness and a shift in emission spectrum.
  • the phosphor particle is washed with a weak acid solution, it is rinsed thoroughly in water before performing the pretreatment.
  • the light emitting action of the light-emitting element 1 will be described with reference to FIG. 45C.
  • an AC electric field is applied between the first electrode 6 and the second electrode 7.
  • the light-emitting element is inserted in a silica tube, and a mixed gas of Ne and Xe is sealed under slight pressure.
  • the AC electric field to be applied is increased gradually, and when a voltage not less than the dielectric breakdown voltage is applied to the gas layers, discharge occurs. Accordingly, electrons are doubled in the gas layers and collide with the porous light-emitting body to excite the luminescence center thereof, so that the porous light-emitting layer emits light.
  • the gas layers function as an electron supply source, and generated electrons are injected into the porous light-emitting layer from both sides of the layer and pass through the light-emitting layer in an avalanche manner while causing surface discharge throughout the porous light-emitting layer.
  • Surface discharge occurs continuously during the application of an electric field. Electrons generated in an avalanche manner during the application of an electric field collide with the luminescence center of the phosphors, so that the phosphor particles 3 are excited to emit light.
  • electrons are injected from both sides of the porous light-emitting layer, i.e., from above and below the layer.
  • the porous light-emitting layer wholly emits light thoroughly, uniformly, and efficiently, resulting in a remarkably increased brightness.
  • the porous light-emitting body having an apparent porosity in a range of not less than 10% to less than 100% is used.
  • a usual phosphor layer without a porous structure light is emitted on its surface but is hardly emitted inside the layer.
  • the porous light-emitting layer light is emitted not only on its surface but also inside the layer, resulting in considerably favorable luminous efficiency. The reason for this is that the porous light-emitting layer allows electrons due to discharge to go into the layer, so that surface discharge occurs throughout the layer, resulting in light emission with a high brightness.
  • an electric field of about 0.57 to 1.2 kV/mm is applied in a thickness direction of the porous light-emitting layer to allow the phosphor particles 3 to emit light. Thereafter, an alternating electric field of about 0.39 to 0.78 kV/mm is applied, so that surface discharge occurs continuously to sustain the light emission of the phosphor particles 3.
  • an electric field of about 0.39 to 0.78 kV/mm is applied, so that surface discharge occurs continuously to sustain the light emission of the phosphor particles 3.
  • light emission is sustained even when the voltage value is decreased to about 60% to 80%. The reason for this is that the sealed rare gas makes an atmosphere in which discharge is more likely to occur. Further, the brightness can be increased remarkably by sealing the rare gas under pressure.
  • a current value during discharge is 0.1 mA or less. It was confirmed that light emission once started was sustained even when the voltage was decreased to about 50% to 80% of the voltage applied initially, and that a high brightness, a high contrast, a high recognition capability, and a high reliability were ensured in light emission of the phosphor particles of each of the three colors as compared with the light-emitting element of Embodiment 2.
  • the light-emitting element without the dielectric layer according to the present embodiment when the light-emitting element without the dielectric layer according to the present embodiment is to be driven to emit light in the atmosphere, it is required that an electric field of about 0.89 to 1.9 kV/mm is applied to allow the phosphor particles 3 to emit light, and that an alternating electric field of about 0.62 to 1.3 kV/mm is applied thereafter, so that surface discharge occurs continuously to sustain the light emission of the phosphor particles 3.
  • the porous light-emitting layer is formed by a thick film process or the like.
  • the light-emitting element unlike a conventional light-emitting element, there is no need to use a thin film formation process for manufacturing the light-emitting element, and neither a vacuum system nor a carrier intensifying layer is necessary. Therefore, the light-emitting element has a simple structure and is manufactured and processed easily. Further, the light-emitting element emits light by surface discharge that occurs due to electrons injected into the porous light-emitting layer, resulting in a high brightness.
  • the present embodiment is characterized in that the porous light-emitting layer wholly emits light thoroughly, unlike a usual phosphor that emits light only on its surface.
  • the luminous efficiency is considerably favorable as compared with that achieved by phosphors that emit ultraviolet rays as in plasma display panels. Further, it is possible to provide a light-emitting element that is to be driven with relatively low power consumption when being used in a large-screen display. Since the partition walls are provided as discharge separation means at both ends of the porous light-emitting layer, crosstalk during light emission can be avoided easily.
  • the light-emitting element according to the present invention emits light by surface discharge.
  • a conventional light-emitting element there is no need to use a thin film formation process for forming the phosphor layer, and neither a vacuum vessel nor a carrier intensifying layer is necessary. Therefore, the light-emitting element can be manufactured easily. Consequently, the light-emitting element of the present invention is useful as a light-emitting body that constitutes a unit pixel of a large-screen display, and also as a light-emitting body to be applied to lighting, a light source, and the like.

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EP1783804A3 (de) * 2005-11-08 2008-05-07 Samsung SDI Co., Ltd. Plasmaanzeigetafel
EP1936661A1 (de) 2006-12-18 2008-06-25 Industrial Technology Research Institute Lichtemittierende Elektronenemissionsvorrichtung und Lichtemissionsverfahren dafür
US7923915B2 (en) 2006-12-18 2011-04-12 Industrial Technology Research Institute Display pixel structure and display apparatus
US7969091B2 (en) * 2007-03-02 2011-06-28 Industrial Technology Research Institute Field-emission apparatus of light source comprising a low pressure gas layer
US8026657B2 (en) 2006-12-18 2011-09-27 Industrial Technology Research Institute Electron emission light-emitting device and light emitting method thereof
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TWI643524B (zh) * 2017-10-03 2018-12-01 王欽戊 Asymmetric structure electroluminescent element with photothermal separation technology

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WO2005051045A1 (ja) 2005-06-02

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