JP2007180036A - Light emitting element, its manufacturing method, and display device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a light emitting element in which the brightness of a fluorescent material is less deteriorated and the reliability thereof is less lowered, and vacuum sealing and application of high-voltage are not required unlike in the case of glow discharge, and advanced thin-film technique is not required. <P>SOLUTION: This light emitting device 1 comprises a porous luminous body 13 including an insulating element having voids and inorganic fluorescent material particles 11, and at least two electrodes 14a, 14b provided to come into contact with the surface of the luminous body 13. A voltage is applied to the at least two electrodes 14a, 14b to generate discharge. When such light emitting devices 1 are two-dimensionally arranged in a matrix form, a simple-structure and low-cost flat display device can be provided. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a light emitting element, a manufacturing method thereof, and a display device in which the light emitting elements are arranged.

  In recent years, flat displays have attracted attention as display devices, and plasma displays have been put into practical use as an example. Plasma displays are attracting attention because they can be easily enlarged, have high brightness, and have a wide viewing angle. However, since the structure of the display is complicated and the manufacturing process is also complicated, the improvement is progressing, but it is still expensive at present.

  In addition, a display using an electroluminescence (EL) phenomenon has been proposed. In inorganic EL, an electrode is arranged on a semiconductor inorganic phosphor, and light is emitted by recombination or excitons of electrons and holes of the inorganic phosphor by applying a voltage, or accelerated electrons of a semiconductor injection collide with the emission center, When the atom or ion which becomes the emission center is excited and returns to its original state, light is emitted (see Non-Patent Documents 1 and 2 below). However, inorganic EL has not been widely used due to the fact that it is difficult to increase the size because it uses a thin film process and the process cost is high. In addition, organic dispersion EL has also been proposed, but there are problems such as difficulty in full color and life characteristics, and this has not been widely used.

In addition to the plasma displays currently in practical use, as a display using discharge, porous particles (metal oxide or polymer spherical particles) are used in a sealed container as described in Patent Document 1. It has been proposed that organic fluorescent molecules are adsorbed on at least the surface of the substrate, an anode and a cathode are formed on the surface, and a direct current electric field is applied to these electrodes to cause discharge to emit light. Further, Patent Document 2 proposes that an electrode is arranged on a phosphor and light is emitted by ultraviolet rays by glow discharge of a rare gas such as He or Xe in a vacuum.
Shigeo Shioya et al. “Light Property Handbook” Asakura Shoten (1984), pp. 523-531 Hiroshi Kobayashi “Principles of Luminescence”, Asakura Shoten (2000), 10-11 JP-A-11-162640 JP 59-18558 A

  The light-emitting element described in Patent Document 1 has a problem of deterioration in luminance and reliability due to vaporization (sublimation) of organic fluorescent molecules due to voltage load and heat generation due to discharge.

  In addition, in the invention described in Patent Document 2, it is necessary to apply a high voltage or vacuum-fill rare gas in order to generate glow discharge.

  The present invention does not cause the above-described problems, causes little deterioration in luminance and reliability of the phosphor, and further does not require vacuum encapsulation such as glow discharge, high voltage application, and further advanced thin film technology. An element and a manufacturing method thereof are provided. In addition, an inexpensive display with a simple structure is provided.

  The present invention includes a porous luminescent material including an insulator having voids and inorganic phosphor particles, and at least two electrodes provided so as to be in contact with the surface of the luminescent material, and a voltage is applied to the at least two electrodes. And a light emitting element that generates discharge and excites the light emitter by the discharge.

  The display device of the present invention is characterized in that the light emitting elements are arranged in a matrix.

  The method for producing a light emitting device of the present invention is a method for producing the above light emitting device, wherein the inorganic phosphor paste is applied to the surface of a plate-like porous body made of an insulator having voids. And a second step of heat-treating the insulator to form a porous light emitter, and a third step of forming at least two electrodes in contact with the surface of the light emitter.

  Another light-emitting device manufacturing method of the present invention is a method for manufacturing the above-described light-emitting device, in which a paste containing insulating fibers and inorganic phosphor particles is applied on a conductive substrate and heat-treated. It includes a first step of forming a porous light emitter and a second step of forming an electrode in contact with the surface of the light emitter.

  Still another light emitting device manufacturing method of the present invention is a method for manufacturing the above light emitting device, in which a porous light emitter is formed by molding and heat-treating a paste containing insulating fibers and inorganic phosphor particles. And a second step of forming at least two electrodes in contact with the surface of the light emitter.

  According to the present invention, it is possible to provide a light emitting device that is less susceptible to deterioration in luminance and reliability of a phosphor, and that does not require vacuum encapsulation such as glow discharge, application of a high voltage, and further advanced thin film technology. By arranging the light emitting elements in a two-dimensional matrix, a flat display device having a simple configuration can be provided.

  The light-emitting element of the present invention is a light-emitting element having a porous light-emitting body having an insulating inorganic material formed on the surface and at least two electrodes in contact with the surface of the light-emitting body. A voltage is applied to the light emitting element to generate a creeping discharge on the surface and inside of the luminous body, and the luminous body is excited to emit light by ultraviolet rays generated by the creeping discharge.

  The light-emitting device of the present invention is a light-emitting device having a porous light-emitting body composed of an aggregate of inorganic phosphor particles whose surface is coated with an insulating inorganic material, and at least two electrodes in contact with the surface of the light-emitting body. . A voltage is applied to the light emitting element to generate a creeping discharge on the surface and inside of the luminous body, and for example, the luminous body is excited and emitted by ultraviolet rays generated by the creeping discharge.

Further, as the insulating inorganic material (insulating metal _{oxides), 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 and PbZrTiO ₃ (PZT) are used, and the standard free energy of formation ΔG _f ^{0 of} the oxide is very high. It is a small substance (for example, −100 kcal / mol or less at room temperature), a stable substance, or a substance having a capacitance of 100 or more. Therefore, it is possible to continue to be an insulating metal oxide that has a high insulation resistance value, easily generates creeping discharge, and is not easily reduced even when creeping discharge occurs.

  Furthermore, the light-emitting element has a structure in which a through-hole is intentionally provided with a needle or the like in the light-emitting body between the electrodes, and creeping discharge easily occurs inside the light-emitting body.

  Further, the light emitting element has a structure in which a substance having a lower resistance than the insulating metal oxide is dispersed inside the light emitting body between the electrodes, and creeping discharge is easily generated even on the inner surface of the light emitting body.

  Further, the light-emitting element has an atmosphere in which an inert gas is sealed inside the light-emitting body and ultraviolet rays are easily generated.

  The light-emitting element of the present invention includes a porous light-emitting body including an insulator having voids and inorganic phosphor particles, and at least two electrodes provided so as to be in contact with the surface of the light-emitting body. A voltage is applied to the electrode to generate a discharge, and the luminous body is excited to emit light by ultraviolet rays generated by the discharge.

  The insulator having the voids is preferably at least one selected from a foam having fibers and open cells. This is because the inorganic phosphor particles are easily attached and easily discharged. The insulator is preferably colorless or white. This is because it does not become an obstacle when emitting phosphors such as red, blue, and green.

  Moreover, it is preferable that a light-emitting body is what made the inorganic fluorescent substance particle adhere to the surface of the insulator which has a space | gap.

  Furthermore, the insulating fiber having voids preferably contains at least one of Al, Si, Ca, Mg, Ti, Zn, and B. Insulation resistance is high, and it is also strong in heat resistance, acid resistance, and alkali resistance. Therefore, a light-emitting element having a structure that easily generates discharge and is resistant to heat and chemicals can be obtained.

  Further, the fiber is preferably an insulating ceramic or glass crushed. This is because the insulation resistance value is high, the heat resistance, the acid resistance and the alkali resistance are strong, the discharge is easily generated, and the structure is strong against heat and chemicals.

  The fiber is preferably a heat-resistant synthetic fiber having a heat distortion temperature of 220 ° C. or higher. The heat distortion temperature means that it does not melt or soften. Since the inside of the luminous body is only filled, it is sufficient to keep the shape without melting or softening. Examples of heat-resistant synthetic fibers having a heat distortion temperature of 220 ° C. or higher include polytetrafluoroethylene (PTFE), tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer (PFA), polychlorotrifluoroethylene (PCTFE), poly Fluorine fiber such as vinylidene fluoride (PVDF), polyvinyl fluoride (PVF), tetrafluoroethylene-hexafluoropropylene copolymer (FEP), tetrafluoroethylene-ethylene copolymer (PETFE), polyimide fiber, aramid fiber Known heat resistant fibers such as polyester fibers, polyamide fibers, polyamide imide fibers, polyester imide fibers, polyether fibers, polyether ether fibers, polysulfone fibers (including meta and para fibers) can be used.

  Furthermore, by covering the inorganic phosphor particles with an insulating inorganic substance, it is possible to efficiently generate a discharge.

Insulating inorganic materials include 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 , and PbZrTiO ₃ (PZT) can be used. These are oxides having a very small standard free energy of formation ΔG _f ⁰ (for example, −100 kcal / mol or less at room temperature), stable materials, or materials having a dielectric constant of 100 or more. Therefore, it is an insulating metal oxide that has a high insulation resistance value, easily generates discharge, and is not easily reduced even if discharge occurs, and has high durability.

  Furthermore, it is good also as a structure which disperse | distributes the substance of lower resistance than an insulating fiber in the inside of the light-emitting body between electrodes, and discharge is easy to generate | occur | produce to the light-emitting body internal surface.

  The inside of the light emitter may be an atmospheric pressure atmosphere, or an atmosphere in which an inert gas is sealed and ultraviolet rays are easily generated.

  Furthermore, when the weight of the insulating fiber is 1, the inorganic phosphor may be blended so that the weight is 0.1 to 10.0. Thereby, it can be set as the structure where discharge is easy to generate | occur | produce to the inside surface of a light-emitting body.

  Furthermore, it is preferable that the insulating fiber has a diameter of 0.1 to 20 μm, a length of 0.5 to 100 μm, and the average particle diameter of the inorganic phosphor particles is 0.1 to 5.0 μm. Thereby, it becomes a structure which discharge tends to generate | occur | produce even to the inside surface of a light-emitting body.

  It is preferable that the porosity of the insulator having voids is in the range of 50% to 90%. This is because the inorganic phosphor particles are easily attached and easily discharged.

  Next, in the first method for producing a light emitting device of the present invention, the inorganic phosphor paste preferably contains inorganic phosphor particles whose surface is covered with an insulating inorganic substance. As a result, it is possible to manufacture a light emitting device having a structure in which discharge is easily generated efficiently.

  Furthermore, it is possible to manufacture a light-emitting element having a structure in which discharge is easily generated efficiently by applying heat treatment after the inorganic phosphor particles are immersed in a metal complex solution, a metal alkoxide solution, or a colloidal solution. It becomes.

  By coating the insulating inorganic material by any one of vapor deposition, sputtering, and CVD, it is possible to manufacture a light-emitting element having a structure in which discharge is easily generated efficiently.

  Further, after the second step and before the third step, the phosphor is immersed in a metal complex solution or a metal alkoxide solution and then heat-treated to easily generate a discharge efficiently by covering the surface with an insulating inorganic substance. It becomes possible to manufacture a light emitting device having a structure.

  In addition, the light-emitting element has a structure in which discharge is easily generated efficiently by coating the surface of the light-emitting body with an insulating inorganic material by any one of vapor deposition, sputtering, and CVD after the second step and before the third step. Can be manufactured.

  Furthermore, a display device can be manufactured by applying three types of inorganic phosphor pastes of red, blue, and green in stripes.

  Further, by providing a light-shielding film or a separator such as a groove between inorganic phosphors of different colors, it becomes possible to manufacture a light-emitting element with a clear color while suppressing color bleeding.

  Further, the inorganic phosphor paste contains a foaming agent, and a light-emitting element having a porous structure can be easily manufactured.

  In the second and third methods for producing a light-emitting device of the present invention, it is preferable that the phosphor is immersed in a metal complex solution, a metal alkoxide solution, or a colloidal solution after the first step and before the second step, and then heat-treated. . Accordingly, it becomes possible to manufacture a light emitting device having a structure in which discharge is efficiently generated by covering the surface of the inorganic phosphor particles with an insulating inorganic substance.

  Furthermore, if the light emitting element of the present invention is used as a display device arranged in a matrix, it can be manufactured at a low cost with a simple configuration.

  Hereinafter, specific embodiments will be described.

(Embodiment 1)
Hereinafter, a light-emitting element of the present invention and a display device using the same will be described using Embodiment 1 with reference to the drawings.

  1 is a cross-sectional view of a light-emitting element 1 according to Embodiment 1 of the present invention, FIG. 2A is a primary particle constituting the light-emitting element 1 shown in FIG. 1, and FIG. 2B is a cross-sectional view of a phosphor particle of the secondary particle. It is. 11 is an inorganic phosphor particle of primary particles or aggregated secondary particles, 12 is a coating layer made of MgO which is an insulating metal oxide, and 13 is composed of phosphor particles 10a and 10b shown in FIGS. 2A and 2B. The porous light emitters 14a and 14b are ITO transparent electrodes provided on the surface of the light emitter 13 so as to have a predetermined interval, and 1 is a light emitting element.

Hereinafter, a method for manufacturing the light-emitting element 1 according to the first embodiment will be described. First, CH ₃ COOH (10 mole ratio), H ₂ O (50 mole ratio), C ₂ H ₅ OH (39 mole ratio) are added to Mg (OC ₂ H ₅ ) ₂ powder (1 mole ratio) which is a metal alkoxide. By stirring and mixing at room temperature, an almost transparent sol-gel solution was prepared. Next, the inorganic phosphor powder (2 molar ratio) was stirred and mixed in the sol-gel solution. Thereafter, the mixed solution was centrifuged, and only the powder was taken in a ceramic vat and dried at 150 ° C. for a whole day and night. Next, the dried powder is calcined in the atmosphere at 400 to 600 ° C. for 2 to 5 hours, and phosphor particles (10a [primary particles], 10b [10b [10a [primary particles], 10b [primary particles] having the MgO coating layer 12 on the surface of the particles 11). Secondary particles]) (see FIG. 2). As the inorganic phosphor particles 11, BaMgAl ₁₀ O ₁₇ : Eu ²⁺ (blue), Zn ₂ SiO ₄ : Mn ²⁺ (green), YBO ₃ : Eu ³⁺ (red) having an average particle diameter of 2 to 3 μm. Using the types, phosphor particles 10a and 10b were produced, respectively. The thickness of the coating layer 12 was 0.1 to 2.0 μm as a result of observing each of the phosphor particles 10a and 10b with a transmission electron microscope (TEM). Next, these phosphor particles 10a and 10b were mixed with 5 wt% polyvinyl alcohol and granulated, and then formed into a disk shape having a diameter of 10 mm and a thickness of 1 mm at a pressure of about 50 MPa. Next, heat treatment was performed at 450 to 1200 ° C. for 2 to 5 hours in a nitrogen atmosphere, so that the porous luminous body 13 was produced. Thereafter, indium tin oxide alloy (ITO) transparent electrodes 14a and 14b were formed on the upper and lower surfaces of the light emitter 13 by sputtering, whereby the light emitting device 1 was obtained.

  Next, a light emitting method of the light emitting element 1 will be described. First, a voltage is applied between the electrodes 14 a and 14 b through the lead wires 2 and 3. The voltage may be either AC or DC. When a voltage is applied, creeping discharge is generated in the coating layer 12, and the discharge is continuously generated in a chain reaction, and ultraviolet rays and visible rays are generated. Next, the generated ultraviolet light photoexcites the particles 11 to emit visible light. Once creeping discharge is started, the discharge is repeated in a chain reaction, and ultraviolet rays and visible rays are generated. Therefore, in order to suppress the adverse effect on the particles 10a and 10b by these rays, the voltage value is lowered after the start of light emission. Is preferred.

  When a voltage of about 0.5 to 1.0 kV / mm was applied with an AC power source or a DC power source, creeping discharge occurred, and light emission started. The current value at this time was 0.1 mA or less. Further, once the light emission started, the light emission continued continuously even when the voltage value was 50 to 80% of the applied voltage. It was confirmed that all three colors of blue, green, and red were light emitting elements with high luminance, high contrast, high recognizability, and high reliability. That is, the light-emitting element 1 of Embodiment 1 has a structure that is structurally close to an inorganic EL, but has a completely different light emission mechanism. In the first embodiment, the particles 11 are excited by light (ultraviolet rays) generated by creeping discharge by voltage application to emit light (photoluminescence). On the other hand, the light emission principle of inorganic EL is as described in the background art section.

Therefore, the phosphor used for the inorganic EL is a semiconductor light emitter as represented by ZnS: Mn ²⁺ , GaP: N, etc., but the particle 11 in the first embodiment is an insulator or a semiconductor. I do not care. That is, even when semiconductor phosphor particles are used, light can be continuously emitted without being short-circuited because they are uniformly coated with an insulating metal oxide.

  Further, the light emitting element 1 does not require vacuum sealing or a high voltage value like glow discharge, and can be expected as a light emitting element having high brightness, high contrast, high recognizability, and high reliability in the atmosphere. Therefore, compared with organic EL and inorganic EL, the structure is simple and can be manufactured easily (there is no need to use advanced thin film technology). Further, it has been found that efficient creeping discharge greatly depends on the filling rate of the particles 10a and 10b. That is, by using the porous light-emitting body 13 as in the first embodiment, creeping discharge is generated not only on the surface of the light-emitting body 13 but also inside, and the particles 11 emit light efficiently. Care must be taken because air discharge occurs if the distance between the particles 10a and 10b constituting the light emitter 13 becomes too large. Ideally, it is desirable that the particles 10a and 10b are in point contact with at least one adjacent particle 10a and 10b in three dimensions.

  When the sintered density of the light emitter 13 (for example, 90% or more of the theoretical density) is improved, creeping discharge is generated only on the surface of the light emitter 13 and the light emission efficiency is low. Therefore, the light emitter 13 having a porous structure less than 90% of the theoretical density is desired. However, if the pores of the light-emitting body 13 are too large and the porosity is excessive, it is expected that the light emission efficiency is lowered and the creeping discharge is less likely to occur. Therefore, ideally, the light-emitting body 13 having a sintered density of 50 to 90% of the theoretical density seems to be appropriate. In addition, if it has mechanical strength, it is not necessary to harden by heat processing. It was confirmed that when a similar voltage application was performed on a green body (green compact) that was not heat-treated at all, light was emitted. It was confirmed that light was emitted in the same manner with respect to a molded body (compact) that was not mixed with polyvinyl alcohol.

  The coating layer 12 is formed to be as uniform and uniform as possible. This is because when the layer is inhomogeneous or non-uniform, light emission is possible, but a decrease in luminance and a deterioration in life (ultraviolet ray deterioration) are likely to occur. Further, as a comparative example, a voltage was applied to a light-emitting body composed only of insulating particles 11 that did not have the coating layer 12 to evaluate the light emission state. Creeping discharge was generated on the surface of the inorganic phosphor particles, and it was confirmed that light was emitted in the same manner as in the present embodiment. However, luminance was instantaneously reduced, and continuous light emission was difficult.

  From this, it can be seen that the coating layer 12 not only has a function of generating creeping discharge and continuing the discharge, but also acts as a protective film for suppressing the ultraviolet ray deterioration and the electric field deterioration of the particles 11.

In the above embodiment, MgO is used for the coating layer 12 because the resistance value is 10 ⁹ Ω · cm or more, and creeping discharge can be generated efficiently. When the resistance value is lower than 10 ⁹ Ω · cm, creeping discharge hardly occurs, and in the worst case, there is a possibility of short circuit, which is not desirable. Therefore, it is desirable to use an insulating metal oxide having a resistance value of 10 ⁹ Ω · cm or more. However, it is desirable to avoid those that block ultraviolet rays or have deliquescence / wind defusing action. Most of these oxides block ultraviolet rays, but can be improved by reducing the coating thickness. The insulating metal oxide constituting the coating layer 12 is a stable substance having a very small standard free energy ΔG _f ⁰ of the oxide (for example, −100 kcal / mol or less at room temperature), or a dielectric constant. May be a substance having a capacity of 100 or more. Therefore, it is desirable not only to have a high insulation resistance value, but also to be an insulating metal oxide that is not easily reduced even when creeping discharge occurs.

Therefore, considering these, 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 Preferably, the coating layer 12 is formed using at least one of ₂ , B ₂ O ₃ , PbTiO ₃ , PbZrO ₃ , and PbZrTiO ₃ (PZT).

  Further, the coating layer 12 may be formed by a physical adsorption method using a chemical adsorption method, a CVD method, a sputtering method, a vapor deposition method, a laser method, a shear stress method or the like other than the sol / gel method. The effect is obtained. What is important is that the coating layer 12 is homogeneous and uniform and does not delaminate. Therefore, before forming the coating layer 12, it is desirable to wash the impurities adhering to the surface by immersing the inorganic phosphor particles 11 in a weak acid solution such as acetic acid, oxalic acid or citric acid. This is because the particles 11 whose surfaces have been cleaned easily form the coating layer 12 having a uniform thickness.

  Furthermore, it is desirable to pretreat the particles 11 in a nitrogen atmosphere at 200 to 500 ° C. for about 1 to 5 hours before forming the coating layer 12. This is because the untreated particles 11 contain a large amount of adsorbed water and crystal water, and when the coating layer 12 is formed in such a state, deterioration of life characteristics such as a decrease in luminance and a shift in emission spectrum becomes remarkable. It is. When the particles 11 are washed with a weakly acidic solution, a pretreatment is performed after the washing.

  Further, the matters to be noted in the heat treatment process for forming the light emitter 13 are the heat treatment temperature and the atmosphere. In the above embodiment, since the heat treatment was performed in a nitrogen atmosphere and at a relatively low temperature (450 to 1200 ° C.), the valence of the doped rare earth atoms of the particles 11 did not change. However, when processing at a higher temperature, it is necessary to be careful because there is a possibility that the valence of the rare earth atoms will change and the solid solution of the coating layer 12 and the particles 11 may occur. Since the density of the light-emitting body 13 is improved as the heat treatment temperature is increased, further caution is required. Accordingly, the ideal heat treatment temperature is preferably 450 to 1200 ° C. The heat treatment atmosphere is preferably carried out in a nitrogen atmosphere in consideration of the valence of rare earth atoms doped in the particles 11.

  The thickness of the coating layer 12 is about 0.1 to 2.0 μm in the present embodiment, but is determined in consideration of the average particle diameter of the particles 11 and the efficiency of creeping discharge. If the average particle size is on the order of submicron, it is thought that it is necessary to coat further thinner. Further, if the thickness of the coating layer 12 is increased, the emission spectrum shifts, the brightness decreases, and the ultraviolet rays are blocked. On the contrary, when the coating layer 12 becomes thin, it is expected that creeping discharge will not occur. Accordingly, the relationship between the average particle diameter of the particles 11 and the thickness of the coating layer 12 is preferably 1/10 to 1/500 of the latter with respect to the former 1.

  The light emitter 13 is ideally composed of particles 10a in which an insulating metal oxide coating layer 12 is provided on primary phosphor particles 11 as shown in FIG. 2A. As shown in FIG. 2B, the phosphor 11 is composed of the luminous particles 10b in which the agglomerated particles 11 are provided with the coating layer 12. However, as a light emitting element, there is no great difference in performance regardless of which phosphor particle is used.

  Further, the electrodes 14a and 14b may be affixed with glass on which an ITO film is formed. If one is transparent, the other may be a metal plate such as aluminum or stainless steel.

(Embodiment 2)
Next, a light-emitting element 1 manufactured using a porous inorganic phosphor will be described with reference to FIG. FIG. 3 is a cross-sectional view of the light-emitting element 1 according to Embodiment 2 of the present invention, in which 21 is a porous inorganic phosphor layer, 12 is a coating layer made of MgO, which is an insulating metal oxide, and 23 is a phosphor. A porous luminous body layer composed of the layer 21, the coating layer 12, and the pores 16, 14a and 14b are ITO transparent electrodes provided on the surface of the luminous body layer 23 with a predetermined interval, 1 is a light emitting element, 15 is The through holes 16 provided in the luminescent layer 23 are pores.

Hereinafter, a method for manufacturing the light-emitting element 1 according to the second embodiment will be described. First, using the same three-color inorganic phosphor powder as in the first embodiment, each was mixed with 5 wt% polyvinyl alcohol, granulated, and then molded into a disk shape having a diameter of 10 mm and a thickness of 1 mm at a pressure of about 50 MPa. did. At this time, several through holes 15 having a diameter of 50 to 500 μm were randomly provided using metal needles. Next, heat treatment was performed at 450 to 1200 ° C. for 2 to 5 hours in a nitrogen atmosphere to prepare a porous inorganic phosphor layer 21. Next, the phosphor layer 21 is immersed for 10 to 30 minutes in a suspension in which Mg (OH) ₂ and ammonia water are mixed in an approximately equimolar ratio, and further dried at 150 ° C. Repeated a few times. Thereafter, the phosphor layer 23 was calcined in the atmosphere at 400 to 600 ° C. for 2 to 5 hours to produce the phosphor layer 23 having the MgO coating layer 12 on the surface of the phosphor layer 21 and having innumerable pores 16. . At this time, it was observed with a transmission electron microscope (TEM) that the coating layer 12 was also formed on the surfaces of the through holes 15 and the pores 16. The thickness of the coating layer 12 was 0.1 to 2.0 μm. Thereafter, electrodes 14a and 14b were formed on the upper and lower surfaces of the light emitting layer 23 by sputtering, and the light emitting device 1 was obtained.

  Next, a light emitting method of the light emitting element 1 will be described. As in the first embodiment, a voltage is applied between the electrodes 14a and 14b through the lead wires 2 and 3. The voltage may be either AC or DC. When a voltage is applied, creeping discharge is generated in the coating layer 12, and the discharge is continuously generated in a chain reaction, and ultraviolet rays and visible rays are generated. Next, the generated ultraviolet light photoexcites the phosphor layer 21 to emit visible light. Once creeping discharge is started, the discharge is repeated in a chain reaction, and ultraviolet rays and visible rays are generated. Therefore, in order to suppress the adverse effect on the luminous body layer 23 by these rays, the voltage value is started after the emission is started. It is preferable to make it 50 to 80% of the hour. When a voltage of about 0.3 to 1.0 kV / mm was applied with an AC power source or a DC power source, creeping discharge occurred, and light emission started. The current value at this time was 0.1 mA or less. Moreover, once light emission started, light emission continued even if the voltage value was lowered. As in the first embodiment, high-quality light emission was confirmed for all three colors of blue, green, and red. The light emission mechanism is the same as that of the first embodiment. In order to efficiently generate creeping discharge and obtain high-quality light emission, a good effect was obtained by executing what is described in the first embodiment.

  Furthermore, in the present embodiment, in order to improve the luminous efficiency, the luminous body layer 23 is provided with the through hole 15 having a diameter of 50 to 500 μm. However, if it is too large, air discharge occurs, so care must be taken. . Ideally, even if the through hole 15 is provided, the luminescent particles are in a three-dimensional point contact with at least one adjacent luminescent particle. Therefore, it is desirable that the diameter of the through hole 15 be less than 2 mm in order to suppress the influence of air discharge and mechanical strength.

  The electrodes 14a and 14b may be affixed with glass on which an ITO film is formed. If one is transparent, the other may be a metal plate such as aluminum or stainless steel.

(Embodiment 3)
In the second embodiment, the phosphor layer 21 is formed by a press. However, in the present embodiment, the case where the light-emitting element 1 is formed by screen printing a paste containing the phosphor particles 10a and 10b is shown in FIG. 4 will be described.

  FIG. 4 is a cross-sectional view of the light-emitting element 1 according to the third embodiment, in which 30 is a ceramic substrate, 33 is a porous light emitter, and 34a and 34b are ITO transparent electrodes. The luminous body 33 is an aggregate of luminous body particles 10a and 10b having a coating layer 12 of MgO which is an insulating metal oxide on the surface of the inorganic phosphor particles 11.

  Next, a method for manufacturing the light-emitting element 1 will be described. First, a paste was prepared by adding ethyl cellulose and α-terpineol to the phosphor particles 10a and 10b shown in the first embodiment. Next, the paste was screen-printed and dried on the ceramic substrate 30 to produce a thick film layer having a printed thickness of about 80 to 100 μm. Thereafter, heat treatment was performed in a nitrogen atmosphere at 450 to 1200 ° C. for 2 to 5 hours, and a very porous light emitting body 33 was produced. The thickness of the light emitter 33 at this time is about 50 to 80 μm. Thereafter, two ITO transparent electrodes 34a and 34b were formed on the upper surface of the light emitter 33 by sputtering. At this time, several through-holes 15 having a diameter of 50 to 500 μm were randomly provided in the light-emitting body 33 using a metal needle. With the above structure, the light-emitting element 1 shown in FIG. 4 was obtained. Next, a light emitting method of the light emitting element 1 will be described. As in the first and second embodiments, a voltage is applied between the electrodes 34a and 34b through the lead wires 2 and 3. The voltage may be either AC or DC. An electric field is generated between the arrows A by applying the voltage. As a result, creeping discharge occurs in the coating layer 12, and the discharge continuously occurs in a chain reaction, and ultraviolet rays and visible rays are generated. Next, the generated ultraviolet light photoexcites the particles 11 to emit visible light. Once the creeping discharge is started, the discharge is repeated in a chain reaction, and ultraviolet rays and visible rays are generated. Therefore, in order to suppress the adverse effect on the illuminant 33 by these rays, the voltage value is It is preferable to set it as 50 to 80%. When a voltage of about 0.1 to 0.8 kV / mm was applied with an AC power source or a DC power source, a creeping discharge occurred, and light emission started. The current value at this time was 0.1 mA or less. Moreover, once light emission started, light emission continued even if the voltage value was lowered. As with the first and second embodiments, high-quality light emission was confirmed for all three colors of blue, green, and red.

  Note that the mechanism of light emission is the same as that in the first embodiment. In order to efficiently generate creeping discharge and obtain high-quality light emission, a good effect was obtained by executing what has been described in the first and second embodiments.

  Furthermore, in the third embodiment, it was confirmed that the light emitting body 33 was made relatively thin compared to the first and second embodiments, and light was emitted even when the electrodes 34a and 34b were formed on the same surface. . However, when the electrodes 34a and 34b are formed on the same surface, it is expected that the surface leaks, so it is necessary to control the distance between the electrodes 34a and 34b. The distance between the electrodes 34a and 34b depends on the thickness of the light emitter 33 and the applied voltage value, but it needs to be at least 10 μm or more.

In the third embodiment, coating the surface of the light emitting element 1 with SiO ₂ or the like is a means for reducing the possibility of surface leakage. In this case, the SiO ₂ on the electrodes 34a and 34b must be removed to ensure conduction.

  The light-emitting element 1 of Embodiment 3 has a structure that is structurally close to an inorganic EL, but has a completely different light emission mechanism. The phosphor particles 11 in the third embodiment may be an insulator or a semiconductor. That is, even if a semiconductor phosphor is used, the coating layer 12 is provided, and therefore, it is possible to emit light continuously without causing a short circuit.

  In Embodiment 3, the light-emitting element 1 was formed by screen printing a paste containing the phosphor particles 10a and 10b.

  The electrodes 34a and 34b may be affixed with glass on which an ITO film is formed. Further, in order to emit light from between the electrodes 34a and 34b, 34a and 34b are not transparent and may be a metal plate (aluminum, stainless steel, etc.).

(Embodiment 4)
Next, an embodiment in which the light emitting device 1 is formed by screen printing a paste containing phosphor powder will be described.

  FIG. 5 is a cross-sectional view of the light-emitting element 1 according to Embodiment 4 of the present invention, in which 21 is a porous inorganic phosphor layer, 12 is a coating layer made of MgO which is an insulating metal oxide, and 23 is a phosphor. A porous luminous body layer composed of the layer 21, the coating layer 12 and the pores 16, 34a and 34b are ITO transparent electrodes provided on the surface of the luminous body layer 23 with a predetermined interval, and 1 is a light emitting element.

  A method for manufacturing the light-emitting element 1 according to the fourth embodiment will be described. First, a paste is prepared by adding ethyl cellulose and α-terpineol to three color inorganic phosphor powders. Next, the phosphor layer 21 was printed on the ceramic substrate 30 by screen printing. At this time, the thickness of the phosphor layer 21 is about 20 to 25 μm.

  Thereafter, heat treatment was performed in a nitrogen atmosphere at 450 to 1200 ° C. for 2 to 5 hours, and a porous phosphor layer 21 including a large number of pores 16 in the layer was produced. At this time, the thickness of the phosphor layer 21 is about 15 to 20 μm. Further, MgO was formed by sputtering on the upper layer portion of the phosphor layer 21 to form a coating layer 12, and a porous luminous body layer 23 composed of the phosphor layer 21, the coating layer 12 and the pores 16 was formed. Thereafter, two ITO transparent electrodes 34a and 34b were formed on the upper surface of the light emitting layer 23 by sputtering. With the above structure, the light-emitting element 1 shown in FIG. 5 was obtained.

  Next, a light emitting method of the light emitting element 1 will be described. As in the third embodiment, a voltage is applied between the electrodes 34a and 34b through the lead wires 2 and 3. The voltage may be either AC or DC. An electric field is generated between the arrows A by applying the voltage. As a result, creeping discharge occurs in the coating layer 12, and the discharge continuously occurs in a chain reaction, and ultraviolet rays and visible rays are generated. Next, the generated ultraviolet light photoexcites the phosphor layer 21 to emit visible light. When creeping discharge starts, the discharge is repeated in a chain reaction, and ultraviolet rays and visible rays are generated. Therefore, in order to suppress the adverse effect on the luminous body layer 23 by these rays, It is preferable to set it as 50 to 80%. When a voltage of about 0.05 to 0.8 kV / mm was applied with an AC power source or a DC power source, creeping discharge was generated, and then light emission started. The current value at this time was 0.1 mA or less. Moreover, once light emission started, light emission continued even if the voltage value was lowered. As in the first to third embodiments, high-quality light emission could be confirmed for all three colors of blue, green, and red.

  Note that the mechanism of light emission is the same as that of the second embodiment. In order to efficiently generate creeping discharge and obtain high-quality light emission, a good effect was obtained by executing what has been described in the first and second embodiments.

  Furthermore, in the fourth embodiment, it was confirmed that the light emitting layer 23 was made relatively thin compared to the second embodiment, and light was emitted even when the electrodes 34a and 34b were formed on the same surface. . However, when the electrodes 34a and 34b are formed on the same surface, it is expected that the surface leaks, so it is necessary to control the distance between the electrodes 34a and 34b. The distance between the electrodes 34a and 34b depends on the thickness of the light-emitting layer 23 and the applied voltage value, but is required to be at least 10 μm.

In the fourth embodiment, coating the surface of the light-emitting element 1 with SiO ₂ or the like is a means for reducing the possibility of surface leakage. In this case, SiO ₂ on the surfaces of the electrodes 34a and 34b must be removed to ensure conduction.

  The light-emitting element 1 of Embodiment 4 has a structure that is structurally close to an inorganic EL, but has a completely different light emission mechanism. The phosphor layer 21 in the fourth embodiment may be an insulator or a semiconductor. That is, even if a semiconductor phosphor is used, the coating layer 12 is provided, and therefore, it is possible to emit light continuously without causing a short circuit.

  Further, in the fourth embodiment, it was confirmed that by providing the through hole 15, light was emitted to the inside of the phosphor layer 21 at a lower voltage. And when the thickness of the fluorescent substance layer 21 was made thinner than 20 micrometers, even if it did not provide the through-hole 15, it confirmed that it light-emitted also inside the fluorescent substance layer 21 enough.

  Furthermore, since the MgO coating layer 12 tends to be amorphous when formed by sputtering, it is desirable to perform crystallization by performing heat treatment at 450 to 1200 ° C. for 2 to 5 hours in air or nitrogen atmosphere.

  The electrodes 34a and 34b may be affixed with glass on which an ITO film is formed. Further, in order to emit light from between the electrodes 34a and 34b, 34a and 34b are not transparent and may be a metal plate (aluminum, stainless steel, etc.).

(Embodiment 5)
FIG. 6 is a cross-sectional view of the light-emitting element 1 according to Embodiment 5 of the present invention, in which 11 is a primary particle or agglomerated secondary phosphor inorganic phosphor particles, and 12 is a coating made of MgO which is an insulating metal oxide. A layer, 13 is a porous illuminant composed of illuminant particles 10a and 10b, 14a and 14b are ITO transparent electrodes provided on the surface of the illuminant 13 with a predetermined interval, 17 is a low-resistance substance, 1 Is a light emitting element.

  A method for manufacturing the light-emitting element 1 according to the fifth embodiment will be described. First, one type of phosphor particles (10a [primary particles], 10b [secondary particles]) (10 to 100 vol ratio) and fine particles Pd, Pt, Ag, Ni, Cu, and Zn produced in the first embodiment. The above metal powder (0.1 to 0.5 μm) (1 vol ratio) was mixed with 5 wt% polyvinyl alcohol, granulated, and then formed into a disk shape having a diameter of 10 mm and a thickness of 1 mm at a pressure of about 50 MPa. Next, heat treatment was performed at 450 to 1200 ° C. for 2 to 5 hours in a nitrogen atmosphere or a reducing atmosphere, so that a porous luminous body 13 was produced. Thereafter, ITO transparent electrodes 14a and 14b were formed on the upper and lower surfaces of the light emitter 13 by sputtering, and the light emitting device 1 was obtained. Lead wires 2 and 3 were connected to this. The metal powder used at this time is Pd. The light emission method is exactly the same as that of the first embodiment, but the difference is that the light emission start voltage value is reduced to about 0.1 to 0.8 kV / mm. Although there are differences depending on the resistance value and the amount of dispersion of the metal powder to be dispersed, creeping discharge occurs at a lower voltage, and high-quality light emission can be confirmed as in the first embodiment, and the practicality can be further improved.

  Note that the mechanism of light emission is the same as that in the first embodiment.

  Note that in the fifth embodiment, it is necessary to control the heat treatment temperature, the atmosphere, and the particle size of the metal powder so that the metal powder 17 does not form a solid solution with the phosphor particles 10a and 10b during the heat treatment.

  As a reason for selecting the metal powder, Pd, Pt, and Ag are metal materials that are difficult to be oxidized and can maintain a low resistance state. Ni and Cu are easy to oxidize, but they are inexpensive metal materials that can maintain a low resistance value by heat treatment in an atmosphere. Further, even if Zn is oxidized, it has a semiconductor property and can maintain a relatively low resistance value. Since these metal materials have different melting points and may be 1000 ° C. or lower, attention must be paid to the heat treatment temperature. The metal powder has a particle size of 0.1 to 0.5 μm, which is finer than the light emitter.

  The electrodes 14a and 14b may be affixed with glass on which an ITO film is formed. If one is transparent, the other may be a metal plate such as aluminum or stainless steel.

  Furthermore, the same effect can be obtained by diffusing a low resistance material having fluidity instead of using metal powder. This will be described in Embodiment 6.

(Embodiment 6)
The light-emitting element 1 manufactured in Embodiment 2 is impregnated in a weak acid solution such as pure water, oxalic acid, acetic acid, boric acid, and citric acid or a conductive polymer such as polyacetylene for 10 to 30 minutes, and the surface of the light-emitting element 1 When a voltage was applied after removing the solution, light emission started at a voltage value of about 0.1 to 0.5 kV / mm. Creeping discharge occurred at a lower voltage, and high-quality light emission was confirmed as in the first embodiment.

  At this time, if the conductive polymer diffuses in a matrix, a short circuit phenomenon occurs or creeping discharge hardly occurs. Therefore, pure water or a weak acid solution requires drying at 50 to 80 ° C. for 5 to 10 minutes, and a conductive polymer requires dilution with alcohol after impregnation.

However, since the sample of the fifth embodiment is easily dried by being left in the atmosphere or generated by creeping discharge, the light-emitting element 1 is coated with SiO ₂ or the like or vacuum sealed as shown in the third embodiment. It is desirable to do. In this case, SiO ₂ on the electrodes 14a and 14b was removed and conducted.

  In the sixth embodiment, since the conductive polymer is impregnated on the surface and inside of the light emitter, there is a possibility that a short-circuit phenomenon may occur in the initial stage of voltage application. At the same time, creeping discharge occurs.

(Embodiment 7)
Hereinafter, a light-emitting element of the present invention and a display device using the same will be described using Embodiment 7 with reference to the drawings.

FIG. 7 is a cross-sectional view of light-emitting element 1 according to Embodiment 7 of the present invention, in which 11 is inorganic phosphor particles, 18 is a SiO ₂ —Al ₂ O ₃ —CaO-based insulating fiber, and 113 is a particle 11. A porous illuminant composed of insulating fibers 18, 14 is an ITO transparent electrode, and 40 is a metal substrate.

Hereinafter, a method for manufacturing the light-emitting element 1 according to the seventh embodiment will be described. BaMgAl ₁₀ O ₁₇ : Eu ²⁺ (blue: B), Zn ₂ SiO ₄ : Mn ²⁺ (green: G), Y ₂ O ₃ : Eu ^{3+ with an} average particle diameter of 2 to 3 μm as inorganic phosphor particles 11 (Red: R) Using 100 kinds of powder, 45 g of butyl acetate, 10 g of BBP (butylbenzyl phthalate), 33.3 g of α-terpineol, 10 g of thinner and 15 g of binder (butyral resin) are mixed. Thus, three types of pastes were produced. Next, the paste is applied to the surface of a plate-like sintered body board made of SiO ₂ —Al ₂ O ₃ —CaO-based insulating fibers 18 having a length of 60 mm, a width of 25 mm, and a thickness of about 0.7 mm in a horizontal stripe shape. , G, and B were screen-printed separately. The width of the stripe was 100 to 200 μm. At this time, the average particle diameter of the particles 11 is about 3 μm, and the board has a fiber diameter of about 10 to 20 μm, a fiber length of about 50 to 100 μm, or a fiber length of about 200 to 500 μm. It is. Further, since the porosity (porosity) of the board is 50 to 90%, the printed paste quickly absorbs the solvent therein. And since the particle | grains 11 are also small in particle size, they permeate the inside of a board. Gradually, the particles 11 become clogged and cannot enter the particles 11 and accumulate on the surface of the board, resulting in the state shown in FIG. That is, the particles 11 are present at a high concentration on one surface of the board.

  When the fiber diameter of the insulating fiber 18 is 20 μm or more and the fiber length is larger than 100 μm, the surface of the board becomes rough and it becomes difficult to uniformly apply the particles 11. Accordingly, the fiber diameter is preferably 20 μm or less and the fiber length is 100 μm or less.

  The insulating fiber also includes acicular particles, whiskers, and particles obtained by pulverizing long fibers.

  Next, after drying in air at 100 to 150 ° C., heat treatment was performed at 450 to 1200 ° C. in air or in a nitrogen atmosphere for 0.25 to 10 hours, whereby the light emitter 113 was manufactured.

  Thereafter, as a test body for confirming discharge, an indium tin oxide alloy (ITO) transparent electrode 14 is formed on the upper surface of the light emitter 113, the metal substrate 40 is connected to the lower surface of the light emitter 113, and the light emitting element 1 is mounted. Obtained. At this time, using a colloidal silica aqueous solution or a colloidal alumina aqueous solution as an adhesive and drying at 100 to 200 ° C., the contact between the light emitter 113 and the electrodes 14 and 40 was improved. It was confirmed that the metal substrate 40 had the same effect even when the electrode paste was baked. When the colloidal silica aqueous solution was used, the life characteristics were extended. The reason is considered that the phosphor particles are coated with colloidal particles, and the colloidal particles act as a coating layer.

  Next, a light emitting method of the light emitting element 1 will be described. First, a voltage was applied between the electrodes 14 and 40 through the lead wires 2 and 3. The voltage may be either AC or DC. Due to the voltage application, a discharge occurred on the surface of the insulating fiber 18, the discharge continued in a chain reaction, and ultraviolet rays and visible light were generated. Next, the generated ultraviolet light photoexcited the particles 11 to emit visible light.

  Once the discharge starts, the discharge is repeated in a chain reaction, and ultraviolet rays and visible light are generated. Therefore, in order to suppress the adverse effect on the light emitter 113 by these light rays, it is preferable to lower the voltage value after the start of light emission. .

  When a voltage of about 0.3 to 1.0 kV / mm was applied with an AC power source or a DC power source, a discharge occurred, and light emission started. The current value at this time was 0.1 mA or less. Further, once the light emission started, the light emission continued continuously even when the voltage value was 50 to 80% of the applied voltage. It was confirmed that all three colors of blue, green, and red are light emitting elements 1 with high luminance, high contrast, high recognizability, and high reliability.

  The light-emitting element 1 of Embodiment 7 has a structure that is structurally close to an inorganic EL, but has a completely different light-emitting mechanism. In other words, the inorganic phosphor particles 11 are excited by light (ultraviolet rays) generated by discharge due to voltage application to emit light (photoluminescence). On the other hand, the light emission principle of inorganic EL is as described in the background art section.

  Further, the light emitting element 1 does not require vacuum sealing or a high voltage value like glow discharge, and can be expected as a light emitting element having high brightness, high contrast, high recognizability, and high reliability in the atmosphere. Therefore, compared with organic EL or inorganic EL, the structure is simple and can be easily manufactured. That is, it is not necessary to use advanced thin film technology.

  Furthermore, it has been found that efficient discharge is highly dependent on the porosity of the insulating fiber 18 board. A dense board with a small porosity is unlikely to generate a discharge, and even if a discharge occurs, light emission occurs only on the surface, resulting in low light emission efficiency. That is, in order to emit light efficiently, the structure of the light emitter 113 in which the particles 11 penetrate into the board is required. By using the porous light emitter 113 as in the seventh embodiment, discharge occurs not only on the surface of the light emitter 113 but also inside, and the inorganic phosphor particles 11 emit light efficiently.

  Further, it has been found that a plurality of insulating fibers 18 constituting the light emitter 113 are overlapped to form a network structure, which is an important factor for the generation of discharge.

  On the contrary, when the porosity of the board is increased, the smoothness of the board surface is impaired or the mechanical strength is weak and brittle. Therefore, the porosity of the board is preferably 50 to 90%.

Furthermore, the reason why the SiO ₂ —Al ₂ O ₃ —CaO fiber is selected as the insulating fiber 18 is that it is thermally and chemically stable, has a resistance value of 10 ⁹ Ω · cm or more, and more structurally 50 to 50 This is because it can have a large porosity of 90%, and is generated by electric discharge on the surface of each fiber, and as a result, electric discharge can be generated in the entire board. If the board is too dense, discharge will only occur on the surface or at the edges. The same effect can be obtained by using a sintered body board containing SiC, ZnO, TiO ₂ , MgO, BN, or Si ₃ N ₄ fibers.

  An important point is the heat treatment condition. It is necessary to control the heat treatment temperature and atmosphere by the composition of the fiber so that the fiber and the inorganic phosphor particles 11 do not react or dissolve in the heat treatment. In this embodiment, the heat treatment is performed in air or in a nitrogen atmosphere for 0.25 to 10 hours, and the temperature is set to the lowest temperature at which organic substances contained in the particles 11 can be removed, that is, 450 to 1200 ° C. It should be noted that if the organic substance is contained in a large amount in the illuminant 113, the light emission characteristics and the life characteristics deteriorate significantly. However, when no organic binder is used, the heat treatment is not necessary. For example, when a slurry obtained by mixing phosphor particles 11 with a colloidal silica aqueous solution is immersed in the insulating fiber 18 board and dried at 100 to 200 ° C. in the air, the porous light emitter 113 is formed.

  In the above embodiment, a light shielding film or a groove may be provided between the R, G, B color inorganic phosphor regions. For example, as shown in FIG. 16A, a light shielding film 20 from the surface side to the inside is formed. The light shielding film can be formed by absorbing paste paint from the surface of the light emitter 113 by coating using a black paste. A preferable width of the light shielding film 20 is 25 to 50 μm, and a preferable depth is 10 μm or more.

  Further, as shown in FIG. 16B, a groove 21 may be formed. By providing the light shielding film or the groove, it is possible to prevent the emission colors from the respective phosphors from being mixed, and a clear full color display can be performed. A preferable width of the groove 22 is 25 to 50 μm, and a preferable depth is 10 μm or more.

(Embodiment 8)
Next, the case where the surface of the inorganic phosphor particles is coated with an insulating inorganic material will be described with reference to FIG.

FIG. 8 is a cross-sectional view of the light-emitting element 1 according to Embodiment 8 of the present invention, 11 is inorganic phosphor particles, 12 is a coating layer, 18 is an SiO ₂ —Al ₂ O ₃ —CaO-based insulating fiber, and 123 is A porous luminous body composed of particles 11 and fibers 18, 14 is an ITO transparent electrode, 40 is a metal substrate, and 1 is a light emitting element.

Hereinafter, a method for manufacturing the light-emitting element 1 according to the eighth embodiment will be described. First, a paste was prepared using the same three-color inorganic phosphor powder as in the seventh embodiment. Next, the paste was screen-printed on the surface of the plate-like sintered body board of the SiO ₂ —Al ₂ O ₃ —CaO insulating fiber 18 having a thickness of about 0.7 mm.

  Next, after drying at 100 to 150 ° C. in air, heat treatment was performed at 450 to 1200 ° C. in air or nitrogen atmosphere for 0.25 to 10 hours. Next, this is immersed in a solution of tetraethyl orthosilicate (TEOS) at room temperature (ethanol as a solvent, the concentration is 50 to 100%), dried, and 0.25 to 0.25 to 450 to 1200 ° C. in air or in a nitrogen atmosphere. Heat treatment was performed for 1 hour to produce a porous luminescent material 123 in which the coating layer 12 was formed on the surfaces of the inorganic phosphor particles 11 and the insulating fibers 18. Thereafter, the ITO transparent electrode 14 and the metal substrate 40 were connected to the upper and lower surfaces of the light emitter 123 to obtain the light emitting element 1. At this time, using a colloidal silica aqueous solution or a colloidal alumina aqueous solution as an adhesive and drying at 100 to 200 ° C., the contact between the light emitter 123 and the electrodes 14 and 40 was improved. It was confirmed that the metal substrate 40 had the same effect even when the electrode paste was baked.

  Next, a light emitting method of the light emitting element 1 will be described. As in the seventh embodiment, a voltage was applied between the electrodes 14 and 40 through the lead wires 2 and 3. The voltage may be either AC or DC. By applying a voltage, a discharge occurred on the surface of the coating layer 12, and the discharge continued in a chain reaction, and ultraviolet rays and visible light were generated. Next, the generated ultraviolet light photoexcited the particles 11 to emit visible light. Once the discharge is started, the discharge is repeated in a chain reaction, and ultraviolet rays and visible rays are generated. Therefore, in order to suppress the adverse effect on the light emitter 123 by these rays, the voltage value is It is preferable to set it as 50 to 80%. When a voltage of about 0.3 to 1.0 kV / mm was applied with an AC power source or a DC power source, discharge was generated and light emission started. The current value at this time was 0.1 mA or less. Moreover, once light emission started, light emission continued even if the voltage value was lowered. As in the seventh embodiment, high-quality light emission was confirmed for all three colors of blue, green, and red.

  Note that the mechanism of light emission is the same as that of the seventh embodiment. In order to efficiently generate discharge and obtain high-quality light emission, a good effect was obtained by carrying out what has been described in Embodiment 7.

  The coating layer 12 was formed to be as uniform and uniform as possible. This is because if the layer is inhomogeneous or non-uniform, light emission is possible, but a decrease in luminance and a deterioration in life (ultraviolet ray deterioration) are likely to occur. The purpose of the coating layer 12 is to prevent UV degradation and moisture degradation of the particles 11 in addition to efficiently generating discharge. Discharge may occur, and luminous efficiency is improved. The thickness of the coating layer 12 is about 0.05 to 2.0 μm in the present embodiment, but is determined in consideration of the average particle diameter of the particles 11 and the fiber diameter of the insulating fibers 18.

  An increase in the thickness of the coating layer 12 is not preferable because the emission spectrum shifts, the luminance decreases, and the ultraviolet rays are blocked. Therefore, the relationship between the average particle diameter of the particles 11 and the thickness of the coating layer 12 is preferably 1/10 to 1/500 for the latter with respect to the former.

In the present embodiment, SiO ₂ is used for the coating layer 12 because it has good film forming properties and is effective in measures against ultraviolet deterioration and moisture deterioration of the particles 11 which are the main purpose.

In addition to the above-described effects, the resistance value is 10 ⁹ Ω · cm or more, and there is an effect that discharge can be generated efficiently. When the resistance value is lower than 10 ⁹ Ω · cm, it is difficult to generate discharge, and in the worst case, there is a possibility of short-circuiting, which is not desirable. Therefore, the coating layer 12 is desirably formed using an insulating metal oxide having a resistance value of 10 ⁹ Ω · cm or more. However, it is desirable to avoid UV rays and those that have water absorption, deliquescence, and wind defusing action. Most of the insulating metal oxides block ultraviolet rays, but can be improved by reducing the thickness.

The insulating metal oxide constituting the coating layer 12 is a stable substance having a very small standard free energy ΔG _f ⁰ of the oxide (for example, −100 kcal / mol or less at room temperature), or a dielectric constant. May be a substance having a capacity of 100 or more. Therefore, it is desirable that not only the insulation resistance value is high but also that it is difficult to be reduced even if a discharge occurs and it can continue to be an insulating metal oxide.

Therefore, considering these, 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, and it is desirable to form a coating layer 12 with at least one kind selected from PbZrTiO ₃ (PZT).

  Further, the coating layer 12 may be formed by a physical adsorption method using a chemical adsorption method, a CVD method, a sputtering method, a vapor deposition method, a laser method, a shear stress method or the like other than the sol / gel method. The effect is obtained. What is important is that the coating layer 12 is as homogeneous and uniform as possible and does not delaminate. Therefore, before forming the coating layer 12, it is desirable to immerse the luminescent material 123 in a weak acid solution such as acetic acid, oxalic acid, or citric acid to wash away impurities adhering to the surface. This is because the phosphor 123 whose surface has been washed easily forms the coating layer 12 having a uniform thickness.

  In addition, the matters to be noted in the two heat treatment steps for forming the light emitter 123 are the heat treatment temperature and the atmosphere. In the present embodiment, since the heat treatment was performed at a relatively low temperature in air or in a nitrogen atmosphere, the valence of the doped rare earth atoms of the inorganic phosphor particles 11 did not change. However, when processing at a higher temperature, it is necessary to be careful because there is a possibility that the valence of the rare earth atoms will change and the solid solution of the coating layer 12 and the particles 11 may occur.

  Therefore, the valence of rare earth atoms is prevented from changing by heat treatment.

The phosphor used in the eighth embodiment may be a semiconductor or an insulator. The phosphor used in the inorganic EL is a semiconductor light emitter as represented by ZnS: Mn ²⁺ , GaP: N, and the like, but the particle 11 in the eighth embodiment may be an insulator or a semiconductor. . In other words, even when semiconductor phosphor particles are used, light is continuously emitted without being short-circuited because they are uniformly coated with the insulating metal oxide coating layer 12. Like Embodiment 7, the coating layer 12 is formed in the surface of the inorganic fluorescent substance particle 11 and the insulating fiber 18 by being immersed in colloidal silica aqueous solution and drying at 100-200 degreeC in the air. It was confirmed that the same effect was obtained even when this coating layer 12 was used.

(Embodiment 9)
In Embodiments 7 and 8, the porous phosphor can be produced by applying an inorganic phosphor paste to a plate-like sintered body board of insulating fibers and performing heat treatment. Next, a method for producing a phosphor from a mixed powder of insulating fibers and inorganic phosphor will be described.

A light-emitting element 1 manufactured using a paste in which inorganic phosphor particles 11 and insulating fibers 18 are mixed will be described with reference to FIG. FIG. 9 is a cross-sectional view of the light-emitting element 1 according to Embodiment 9 of the present invention, 11 is inorganic phosphor particles, 12 is a coating layer, 18 is a SiO ₂ —Al ₂ O ₃ —CaO-based insulating fiber, and 133 is A porous luminous body composed of particles 11 and insulating fibers 18, 14 is an ITO transparent electrode, 40 is a metal substrate, and 1 is a light emitting element.

Hereinafter, a method for manufacturing the light-emitting element 1 according to the ninth embodiment will be described. First, using the same three-color inorganic phosphor powder as in Embodiments 7 and 8, fiber powder was blended in a 1/10 to 10 weight ratio with respect to the inorganic phosphor powder 1 to prepare a mixed powder. Next, an organic solution such as ethyl cellulose and α-terpineol or butyl acetate was added, and a paste was prepared using a kneader such as a triple roll. The fiber 18 used at this time had a fiber diameter of about 1 to 2 μm and a fiber length of about 25 to 50 μm. Next, the paste is screen-printed on the Pt metal substrate 40, dried in air at 100 to 150 ° C., and then heat treated at 450 to 1200 ° C. in air or nitrogen atmosphere for 0.25 to 10 hours to insulate the particles 11 The porous light-emitting body 133 comprised of the conductive fiber 18 was obtained. At this time, the coating thickness after the heat treatment was 10 to 500 μm. In addition, when the insulating fiber 18 is mixed, the smoothness of the printed surface is deteriorated. Therefore, it is preferable to prepare a paste after previously mixing and pulverizing the inorganic phosphor powder and the insulating fiber 18 with a ball mill or the like because the smoothness is improved. Next, this is immersed in a tetraethyl orthosilicate (TEOS) solution, dried, and then subjected to heat treatment at 450 to 1200 ° C. in air for 0.25 to 10 hours to form SiO on the surfaces of the inorganic phosphor particles 11 and the insulating fibers 18. ₂ A light-emitting body 133 on which the coating layer 12 was formed was produced. Thereafter, the ITO transparent electrode 14 is connected to the upper surface of the light emitter 133 to obtain the light emitting element 1. At this time, the contact property between the light emitter 133 and the electrode 14 was improved by drying at 100 to 200 ° C. using an aqueous colloidal silica solution or an aqueous colloidal alumina solution as an adhesive.

  Next, a light emitting method of the light emitting element 1 will be described. As in the seventh and eighth embodiments, a voltage was applied between the electrodes 14 and 40 through the lead wires 2 and 3. The voltage may be either AC or DC. By applying voltage, a discharge occurred on the surface of the coating layer 12, and the discharge continued in a chain reaction, and ultraviolet rays and visible light were generated.

  Next, the generated ultraviolet light photoexcites the inorganic phosphor particles 11 to emit visible light. Once the discharge is started, the discharge is repeated in a chain reaction, and ultraviolet rays and visible light are generated. Therefore, in order to suppress the adverse effect on the light emitter 133 by these light rays, It is preferable to set it as 50 to 80%. When a voltage of about 0.3 to 1.0 kV / mm was applied with an AC power source or a DC power source, discharge was generated and light emission started. The current value at this time was 0.1 mA or less. Moreover, once light emission started, light emission continued even if the voltage value was lowered. As in the seventh and eighth embodiments, high-quality light emission could be confirmed for the three colors of blue, green, and red.

  The light emission mechanism and the like are the same as in the seventh and eighth embodiments. In order to generate discharge efficiently and to obtain high-quality light emission, a good effect was obtained by carrying out what has been described in Embodiments 7 and 8.

  In the present embodiment, since the light emitter 133 is formed using a paste made of a mixture of the particles 11 and the insulating fibers 18, the depth of the particles 11 compared to the seventh and eighth embodiments. The concentration gradient in the direction was suppressed, and the entire luminous body 133 emitted light uniformly.

  In addition, describing the mixing ratio of the particles 11 and the insulating fibers 18, when the amount of the former powder is increased, a dense structure is formed and electric discharge is less likely to occur. Conversely, when the amount of the latter powder increases, a porous structure is obtained, but the luminance tends to decrease. Accordingly, the mixing ratio of the insulating fibers 18 to the particles 11 is 1/10 to 10, preferably 1/5 to 5, by weight.

Furthermore, the insulating fiber 18 can generate a discharge in a network form. Therefore, considering the structure of the light emitter 133 and the light emission intensity, the finer one is better. The shape of the SiO ₂ —Al ₂ O ₃ —CaO fiber used as a commercially available product was about 1 to 2 μm in fiber diameter and about 25 to 50 μm in fiber length, but the fiber length was shortened by mechanical grinding (about 5 μm). It is also possible to use it. However, if it is too short, it is difficult to form a network, and it is difficult for electric discharge to occur. Accordingly, it is preferable that the fiber diameter is about 0.5 μm and the fiber length is about 3 μm.

  In addition, the thickness of the light-emitting body 133 after heat treatment is 10 to 500 μm. However, in screen printing, there is a risk of short-circuiting when a voltage is applied, so it is considered that a coating thickness of at least 5 μm is necessary. The optimum coating thickness was 10 to 100 μm. However, the thickness can be further reduced when the film is formed by vapor deposition, sputtering, CVD, or the like.

  The coating layer 12 is formed to be as uniform and uniform as possible. This is because when the layer is inhomogeneous or non-uniform, light emission is possible, but a decrease in luminance and a deterioration in life (ultraviolet ray deterioration) are likely to occur. The purpose of the coating layer 12 is to prevent UV degradation and moisture degradation of the particles 11 in addition to efficiently generating discharge. Since discharge may occur, the luminous efficiency is very good. The thickness of the coating layer 12 is about 0.05 to 2.0 μm in the present embodiment, but is determined in consideration of the average particle diameter of the particles 11 and the fiber diameter of the fibers 18. An increase in the thickness of the coating layer 12 is not preferable because the emission spectrum shifts, the luminance decreases, and the ultraviolet rays are blocked. Accordingly, the relationship between the average particle diameter of the inorganic phosphor particles 11 and the thickness of the coating layer 12 is preferably 1/10 to 1/500 for the latter with respect to the former 1.

  The coating layer 12 is formed on the surfaces of the inorganic phosphor particles 11 and the insulating fibers 18 by immersing in an aqueous colloidal silica solution instead of a TEOS solution as in the above embodiment and drying in air at 100 to 200 ° C. The It was confirmed that the same effect was obtained even when this coating layer 12 was used.

  In the ninth embodiment, the coating layer 12 is formed. However, even if the coating layer 12 is not formed, since the fibers entangled in a mesh form easily generate discharge, the light emitter 133 emits light. However, discharge deterioration and ultraviolet light deterioration were suppressed when the coating layer 12 was formed.

  Further, in the ninth embodiment, the phosphor 133 is applied to the upper layer portion of the Pt metal substrate 40 and heat treatment is performed. For example, the light emitter 133 is applied on a PET film, and after the film is peeled off, the heat treatment is performed. It may be pasted. In addition, the adhesive strength increased by drying at 100-200 degreeC using colloidal silica aqueous solution or colloidal alumina aqueous solution as an adhesive agent at this time. The metal substrate 40 at this time may be a noble metal other than Pt or a base metal.

(Embodiment 10)
Next, the case where electrodes are formed on the same surface will be described with reference to FIG.

FIG. 10 is a cross-sectional view of the light-emitting element 1 according to Embodiment 10 of the present invention, 11 is inorganic phosphor particles, 12 is a coating layer, 18 is an SiO ₂ —Al ₂ O ₃ —CaO-based insulating fiber 18, 133. Is a porous luminous body composed of coated particles 11 and coated insulating fibers 18, 34a and 34b are ITO transparent electrodes provided on the surface of the luminous body 133, 30 is a substrate of ceramic, glass, metal, etc. Reference numeral 1 denotes a light emitting element.

  Hereinafter, a method for manufacturing the light-emitting element 1 according to the tenth embodiment will be described. First, the same paste as in Embodiment 9 was used. Next, the paste is screen-printed on the substrate 30, dried at 100 to 150 ° C. in air, and then heat treated at 450 to 1200 ° C. in air or nitrogen atmosphere for 0.25 to 10 hours. A porous luminous body 133 composed of insulating fibers 18 was obtained. At this time, the coating thickness after the heat treatment was 10 to 500 μm. Next, this was immersed in a magnesium complex solution, dried, and then subjected to heat treatment at 450 to 600 ° C. in air for 0.25 to 1 hour, whereby the MgO coating layer 12 was formed on the surfaces of the particles 11 and the fibers 18. A body 133 was produced. The reason why the complex solution is used here is that it is easy to form a uniform and thin coating layer 12 as compared with a sol-gel solution or the like. Thereafter, ITO transparent electrodes 34a and 34b were formed on the upper surface of the light emitter 133 by sputtering, and the light emitting device 1 was obtained.

  The electrodes 34a and 34b may be made of glass on which ITO is formed. In order to emit light between the electrodes 34a and 34b, the electrodes 34a and 34b are not transparent and may be made of aluminum or stainless steel. .

  Next, a light emitting method of the light emitting element 1 will be described. A voltage was applied between the electrodes 34 a and 34 b through the lead wires 2 and 3. The voltage may be either AC or DC. At this time, an electric field is generated between the electrodes 34a and 34b (arrow A). By applying voltage, a discharge occurred on the surface of the coating layer 12, and the discharge continued in a chain reaction, and ultraviolet rays and visible light were generated. Next, the generated ultraviolet light photoexcited the inorganic phosphor particles 11 to emit visible light. Once the discharge is started, the discharge is repeated in a chain reaction, and ultraviolet rays and visible light are generated. Therefore, in order to suppress the adverse effect on the light emitter 133 by these light rays, It is preferable to set it as 50 to 80%. When a voltage of about 0.3 to 1.0 kV / mm was applied with an AC power source or a DC power source, discharge was generated and light emission started. The current value at this time was 0.1 mA or less. Moreover, once light emission started, light emission continued even if the voltage value was lowered. High-quality light emission was confirmed in the three colors of blue, green, and red as in the seventh to ninth embodiments. The light emission mechanism and the like are the same as those in the seventh to ninth embodiments. In order to generate electric discharge efficiently and to obtain high-quality light emission, a good effect was obtained by executing what has been described in Embodiments 7 to 9.

  The effect and purpose of the coating layer 12 are the same as those described in the eighth and ninth embodiments.

In the tenth embodiment, since the phosphor 133 is formed using a paste made of a mixture of the inorganic phosphor particles 11 and the insulating fibers 18 mainly composed of the SiO ₂ —Al ₂ O ₃ —CaO based material. In addition, as compared with Embodiments 7 and 8, the concentration gradient in the depth direction of the particles 11 was suppressed, and the entire luminous body 133 emitted light uniformly.

  Further, when the particles 11 and the fibers 18 are mixed, when the amount of the former powder is increased, a dense structure is obtained and electric discharge is hardly generated. Conversely, when the amount of the latter powder increases, a porous structure is obtained, but the luminance tends to decrease. Accordingly, the mixing ratio of the fibers 18 with respect to the particles 11 is in the range of 1/10 to 10, preferably 1/5 to 5, by weight.

  Furthermore, in the tenth embodiment, it was confirmed that the light emitting body 133 was further reduced in thickness as compared with the ninth embodiment, and light was emitted even when the electrodes 34a and 34b were formed on the same surface.

  However, when the electrodes 34a and 34b are formed on the same surface, it is expected that the surface leaks, so it is necessary to control the distance between the electrodes 34a and 34b. The distance between the electrodes 34a and 34b depends on the thickness of the light emitter 133 and the applied voltage value, but it needs to be at least 10 to 1000 μm or more. Preferably it is 50-500 micrometers.

  In the tenth embodiment, providing the coating layer 12 on the surface of the light emitting element 1 also serves as a means for reducing the possibility of surface leakage. In this case, the coating layer 12 on the surfaces of the electrodes 34a and 34b must be removed to ensure conduction.

  The coating layer 12 is formed on the surfaces of the inorganic phosphor particles 11 and the insulating fibers 18 by immersing in a colloidal silica aqueous solution instead of the magnesium complex aqueous solution as in the above embodiment and drying in air at 100 to 200 ° C. Is done. It was confirmed that the same effect was obtained even when this coating layer 12 was used.

  In the tenth embodiment, the coating layer 12 is formed. However, even if the coating layer 12 is not formed, the illuminator 133 emits light due to the discharge of the insulating fibers 18 entangled in a mesh shape. However, when the coating layer 12 was formed, discharge deterioration and ultraviolet light deterioration were suppressed.

  Furthermore, in the tenth embodiment, the phosphor 133 is applied to the upper layer portion of the substrate 30 and subjected to heat treatment. However, for example, the light emitter 133 may be applied onto a PET film, peeled off and then heat treated, and the heat treated substrate 30 attached. Good. In addition, the adhesive strength increased by drying at 100-200 degreeC using colloidal silica aqueous solution or colloidal alumina aqueous solution as an adhesive agent at this time.

(Embodiment 11)
In Embodiments 8 to 10, the coating layer 12 was attached to both the inorganic phosphor 11 and the insulating fiber 18. Next, the case where the coating layer 12 adheres only to the particles 11 will be described with reference to FIG.

FIG. 11 is a cross-sectional view of the light-emitting element 1 according to Embodiment 11 of the present invention, 11 is inorganic phosphor particles, 18 is an insulating fiber mainly composed of SiO ₂ —Al ₂ O ₃ —CaO, and 143 is particles. 11 is a porous light emitter composed of 11 and fibers 18, 34a and 34b are ITO transparent electrodes provided on the surface of the light emitter 143, 30 is a substrate composed of ceramic, glass, metal, etc., and 1 is a light emitting element.

  Hereinafter, a method for manufacturing the light-emitting element 1 according to Embodiment 11 will be described. First, each of the three-color inorganic phosphor particles 11 is immersed in a magnesium complex solution, dried, and then heat treated at 450 to 600 ° C. in air for 0.25 to 1 hour, and then pulverized to form inorganic phosphor particles 11. An MgO coating layer 12 was formed on the surface. Next, 1/10 to 10 of the insulating fiber 18 was blended in a weight ratio with respect to the particles 11 to which the coating layer 12 was applied to prepare a mixed powder. Further, an organic solution such as α-terpineol or butyl acetate is added, and a paste is prepared using a kneader such as a three roll. The fiber 18 used at this time had a fiber diameter of about 1 to 2 μm and a fiber length of about 25 to 50 μm. Next, the paste 11 is screen-printed on the substrate 30, dried at 100 to 150 ° C. in the air, and then heat-treated at 450 to 1200 ° C. in the air or in a nitrogen atmosphere for 0.25 to 10 hours. And a porous luminous body 143 composed of fibers 18 were obtained. At this time, the coating thickness after the heat treatment was 10 to 500 μm. Thereafter, ITO transparent electrodes 34 a and 34 b were connected to the upper surface of the light emitter 143 to obtain the light emitting element 1. Moreover, since light emission is generated between the electrodes 34a and 34b, it is not transparent and may be a metal plate (aluminum, stainless steel, or the like).

  Next, a light emitting method of the light emitting element 1 will be described. As in the tenth embodiment, a voltage was applied between the electrodes 34 a and 34 b through the lead wires 2 and 3. The voltage may be either AC or DC. At this time, an electric field is generated between the electrodes 34a and 34b (arrow A). By applying voltage, a discharge occurred on the surface of the coating layer 12, and the discharge continued in a chain reaction, and ultraviolet rays and visible light were generated.

  Next, the generated ultraviolet light photoexcites the particles 11 to emit visible light. Once the discharge is started, the discharge is repeated in a chain reaction, and ultraviolet rays and visible rays are generated. Therefore, in order to suppress the adverse effect on the illuminant 143 by these rays, the voltage value after the start of the emission is changed. It is preferable to set it as 50 to 80%. When a voltage of about 0.3 to 1.0 kV / mm was applied with an AC power source or a DC power source, discharge was generated and light emission started. The current value at this time was 0.1 mA or less. Moreover, once light emission started, light emission continued even if the voltage value was lowered. High-quality luminescence was confirmed in the three colors of blue, green, and red, as in Embodiments 7 to 10.

  The light emission mechanism is the same as in Embodiments 7 to 10. In order to efficiently generate discharge and obtain high-quality light emission, a good effect was obtained by executing what has been described in Embodiments 7 to 10.

  The effect and purpose of the coating layer 12 are the same as those described in the eighth to tenth embodiments.

  In the present embodiment, since the luminous body 143 is formed using a paste made of a mixture of the particles 11 and the fibers 18, the concentration of the particles 11 in the depth direction compared to the seventh and eighth embodiments. The gradient was suppressed and the entire light emitter 143 emitted light uniformly.

  In addition, when the mixing ratio of the particles 11 and the fibers 18 is described, when the amount of the former powder is increased, a dense structure is obtained and electric discharge is hardly generated. Conversely, when the amount of the latter powder increases, a porous structure is obtained, but the luminance tends to decrease. Accordingly, the mixing ratio of the fibers 18 with respect to the particles 11 is in the range of 1/10 to 10, preferably 1/5 to 5, by weight.

  Furthermore, in the eleventh embodiment, it was confirmed that the light emitter 143 was made thinner than the ninth embodiment, and light was emitted even when the electrodes 34a and 34b were formed on the same surface. However, when the electrodes 34a and 34b are formed on the same surface, it is expected that the surface leaks, so it is necessary to control the distance between the electrodes 34a and 34b. The distance between the electrodes 34a and 34b depends on the thickness of the light emitter 143 and the applied voltage value, but is required to be at least 10 to 1000 μm in order to suppress air discharge. Preferably it is 50-500 micrometers.

  In the eleventh embodiment, light emission was started at a slightly lower voltage value than in the tenth embodiment. The reason for this is considered to be that the insulating fiber 18 is not provided with the coating layer 12 having a high resistance value.

  Further, in the tenth embodiment, the light emitter 143 is applied to the upper layer portion of the substrate 30 and heat treatment is performed. . In addition, the adhesive strength increased by drying at 100-200 degreeC using colloidal silica aqueous solution or colloidal alumina aqueous solution as an adhesive agent at this time.

  Moreover, the coating layer 12 which has the same effect is formed by immersing the inorganic fluorescent substance particle 11 in colloidal silica aqueous solution instead of a magnesium complex solution, drying at 100-200 degreeC in the air, and grind | pulverizing. It was confirmed.

(Embodiment 12)
In the eleventh embodiment, an inorganic phosphor powder or a powder obtained by mixing an inorganic phosphor powder with (fiber) powder was used as a base. In Embodiment 12, a light-emitting element 1 manufactured using a paste to which a foaming agent is further added will be described with reference to FIGS.

12 is a cross-sectional view of light-emitting element 1 according to Embodiment 12 of the present invention, 11 is an inorganic phosphor particle, 18 is an insulating fiber mainly composed of a SiO ₂ —Al ₂ O ₃ —CaO system, and 153 is a particle. 11 is a porous light emitter composed of 11 and fibers 18, 34a and 34b are ITO transparent electrodes provided on the surface of the light emitter 153, 30 is a substrate made of ceramic, glass, metal, etc. 1 is a light emitting element.

  Hereinafter, a method for manufacturing the light-emitting element 1 according to the twelfth embodiment will be described. First, a thermal decomposition type chemical foaming agent was additionally added to the paste used in Embodiment 11 in an amount of 1 to 25 wt%. As the chemical foaming agent used at this time, organic thermal decomposition type foaming agents such as azo compound type, nitroso compound type and hydrazine compound type, bicarbonate type and carbonate type inorganic thermal decomposition type foaming agents were used. Moreover, the average particle diameter of the foaming agent at this time was 5-10 micrometers. Next, a paste is screen-printed on the substrate 30, dried in air at 50 to 250 ° C., and foamed. Then, the porous light-emitting body 153 comprised by the particle | grains 11 and the fiber 18 which have the coating layer 12 by heat-processing at 450-1200 degreeC in the air or nitrogen atmosphere for 0.25-10 hours was obtained. The coating thickness after the heat treatment was 20 to 1000 μm. In order to suppress the deformation of the light-emitting body 153 due to the rapid thermal expansion of the foaming agent, drying was performed from room temperature and performed slowly over time. With a chemical foaming agent, when temperature rises to 150-250 degreeC, it will thermally decompose and generate | occur | produce gas, such as nitrogen gas and a carbon dioxide gas, As a result, the light-emitting body 153 is thermally expanded. Therefore, it is preferable to use an organic thermal decomposition type foaming agent.

  Hereinafter, a light-emitting element 1 was manufactured using the same method as in Embodiment 11. Further, the light emitting method and the light emitting mechanism are the same as those in the eleventh embodiment. That is, a voltage was applied between the electrodes 34 a and 34 b through the lead wires 2 and 3. The voltage may be either AC or DC. At this time, an electric field is generated between the electrodes 34a and 34b (arrow A). By applying voltage, a discharge occurred on the surface of the coating layer 12, and the discharge continued in a chain reaction, and ultraviolet rays and visible light were generated.

  Next, the generated ultraviolet light photoexcites the inorganic phosphor particles 11 to emit visible light. Once the discharge started, the discharge was repeated in a chain reaction to generate ultraviolet rays and visible light.

  Since the volume of the foaming agent is increased by mixing the foaming agent and the efficiency of discharge is further improved, the light-emitting element 1 manufactured in Embodiment 12 emits light at a voltage value about 10% lower than that of the light-emitting element manufactured in Embodiment 11. Started. The elasticity is increased as compared with the light emitting element manufactured in Embodiment Mode 11, and for example, the light emission starting voltage value can be lowered by pressurizing the light emitting element 1. Further, the mixing ratio of the foaming agent is preferably 1 to 10 wt% with respect to the particles 11, and if it is more than this, the mechanical strength may be weakened or the emission intensity may be lowered in extreme cases.

(Embodiment 13)
In Embodiments 7 to 12, an inorganic phosphor paste is applied to the surface of the porous body composed of the insulating fibers 18 or a paste in which the insulating fibers 18 and the inorganic phosphor particles 18 are mixed is applied. Thus, the light emitting device 1 was manufactured. In this thirteenth embodiment, a light-emitting element 1 manufactured by sheet molding will be described with reference to FIGS.

FIG. 13 is a cross-sectional view of the light-emitting element 1 according to Embodiment 13 of the present invention, 11 is inorganic phosphor particles, 18 is an insulating fiber mainly composed of a SiO ₂ —Al ₂ O ₃ —CaO system, and 163 is a particle. 11 is a porous luminous body composed of 11 and fibers 18, 14 is an ITO transparent electrode provided on the surface of the luminous body 163, 40 is a metal substrate, and 1 is a light emitting element.

  Hereinafter, a method for manufacturing the light-emitting element 1 according to the thirteenth embodiment will be described.

  First, the inorganic phosphor particles 11 and the insulating fibers 18 were mixed at a weight ratio of 2: 1. 100 g of the mixed powder was mixed with 35 g of butyl acetate, 0.5 g of BBP, 16 g of butyl cellosolve, 8 g of ethanol, and 12 g of butyral resin to prepare a slurry.

  Next, it shape | molded so that the sheet | seat thickness might be set to about 25 micrometers using the sheet forming machine. Thereafter, 2 to 10 sheets were laminated with a laminator, and the thickness after lamination was adjusted to about 50 to 250 μm.

  Next, heat treatment was performed at 450 to 1200 ° C. in air or a nitrogen atmosphere for 0.25 to 10 hours, so that a light-emitting body 163 was manufactured. At this time, the thickness of the light emitter 163 was 45 to 250 μm.

  Thereafter, the ITO transparent electrode 14 and the metal substrate 40 were connected to the upper and lower surfaces of the light emitter 163 to obtain the light emitting element 1.

  As in the seventh to ninth embodiments, a voltage is applied between the electrodes 14 and 40. The voltage may be either AC or DC. By applying voltage, a discharge occurred on the surface of the electrically insulating fiber 18, and the discharge continued in a chain reaction, and ultraviolet rays and visible light were generated.

  Next, the generated ultraviolet light photoexcites the particles 11 to emit visible light. Once the discharge is started, the discharge is repeated in a chain reaction, and ultraviolet rays and visible rays are generated. Therefore, in order to suppress the adverse effect on the light emitter 163 by these rays, It is preferable to set it as 50 to 80%. When a voltage of about 0.3 to 1.0 kV / mm was applied with an AC power source or a DC power source, discharge was generated and light emission started. The current value at this time was 0.1 mA or less. Moreover, once light emission started, light emission continued even if the voltage value was lowered. As in the seventh embodiment, high-quality light emission was confirmed for all three colors of blue, green, and red.

  The light emission mechanism is the same as in Embodiments 7 to 12. In order to generate discharge efficiently and to obtain high-quality light emission, a good effect was obtained by executing what has been described in Embodiments 7 to 12.

  In the thirteenth embodiment, when bonding the light emitter 163 to the electrode 14 and the metal substrate 40, the adhesive strength was increased by drying at 100 to 200 ° C. using a colloidal silica aqueous solution or a colloidal alumina aqueous solution as an adhesive. Moreover, it was confirmed that the coating layer 12 was formed by being immersed in colloidal silica aqueous solution and drying at 100-200 degreeC in the air.

  In the thirteenth embodiment, the coating layer 12 is not provided, but the same effect occurs even if it is provided. However, discharge deterioration and ultraviolet light deterioration were suppressed when the coating layer 12 was formed.

(Embodiment 14)
In Embodiments 7 to 13, since an organic binder was used, a degreasing step was required during the production process, and it was necessary to perform heat treatment at 450 to 1200 ° C. in air or in a nitrogen atmosphere for 0.25 to 10 hours. Then, the method to produce the porous light-emitting body 173 by drying at 100 to 200 ° C. in the air by using an aqueous binder will be described.

This will be described with reference to FIG. First, the inorganic phosphor powder 11 and the insulating fiber 18 mainly composed of SiO ₂ —Al ₂ O ₃ —CaO were mixed at a weight ratio of 2: 1. A slurry was prepared by mixing 50 g of a 5 wt% colloidal silica aqueous solution or colloidal alumina aqueous solution with respect to 100 g of the mixed powder.

  Next, the slurry was placed on the Al metal foil 41 and dried with a dryer at 100 to 200 ° C. for 0.25 to 10 hours to produce a light emitter 173 having a thickness of about 25 to 1000 μm. Then, the ITO transparent electrode 14 was connected to the upper surface of the light emitter 173, and the light emitting element 1 was obtained.

  As in the thirteenth embodiment, a voltage was applied between the electrodes 14 and 40 through the lead wires 2 and 3. The voltage may be either AC or DC. By applying a voltage, a discharge occurred on the surface of the insulating needle-like particles (fibers) 18, and the discharge continued in a chain reaction, and ultraviolet rays and visible rays were generated.

  Next, the generated ultraviolet light photoexcited the particles 11 to emit visible light. Once the discharge is started, the discharge is repeated in a chain reaction, and ultraviolet rays and visible rays are generated. Therefore, in order to suppress the adverse effect of these rays on the illuminant 173, the voltage value is changed to It is preferable to set it as 50 to 80%. When a voltage of about 0.3 to 1.0 kV / mm was applied with an AC power source or a DC power source, discharge was generated and light emission started. The current value at this time was 0.1 mA or less. Moreover, once light emission started, light emission continued even if the voltage value was lowered. As in the seventh embodiment, high-quality light emission was confirmed for all three colors of blue, green, and red.

  Note that the mechanism of light emission is the same as that in the thirteenth embodiment. In order to efficiently generate discharge and obtain high-quality light emission, a good effect was obtained by executing what is described in Embodiment 13.

  At this time, heat treatment was performed at 450 to 1200 ° C. in air or nitrogen atmosphere for 0.25 to 10 hours to produce the light emitter 173, and it was confirmed that the same light emission phenomenon occurred.

  In the fourteenth embodiment, the colloidal particles are formed on the surfaces of the inorganic phosphor particles 11 and the insulating fibers 18 to form the coating layer 12. That is, it was also confirmed that the colloidal silica aqueous solution or the colloidal alumina aqueous solution used as the binder formed the coating layer 12. In addition, instead of colloidal silica aqueous solution or colloidal alumina aqueous solution, as an organic binder, fluorine resin such as polyimide, BCB (benzocyclobutene), PTFE (polytetrafluoroethylene), aramid, PBO (polyparaphenylene benzobisoxazole), Totally aromatic polyester, epoxy resin, cyanate ester resin, phenol resole resin, PPE (polyphenylene ether) resin, bismaleimide triazine resin, unsaturated polyester resin, PPE (polyphenylene ether) resin, PEEK (polyether ether ketone) resin, PEK A thermosetting resin such as a (polyetherketone) resin or a thermoplastic resin can also be used.

(Embodiment 15)
Next, a method for producing a porous light emitter 183 using ZnO-based whiskers as insulating needle-like particles will be described with reference to FIG. First, the particles 11 and the ZnO whiskers 19 were mixed at a weight ratio of 2: 1. A slurry was prepared by mixing 50 g of a 5 wt% colloidal silica aqueous solution or a colloidal alumina aqueous solution with respect to 100 g of the mixed powder. Next, the slurry was placed on the Cu metal foil 41 and dried with a dryer at 100 to 200 ° C. for 0.25 to 10 hours to produce a porous luminous body 183 having a thickness of about 25 to 1000 μm. Thereafter, the ITO transparent electrode 14 was connected to the upper surface of the light emitter 183, and the light emitting element 1 was obtained.

  Next, as in the fourteenth embodiment, a voltage was applied between the electrodes 14 and 40 through the lead wires 2 and 3. The voltage may be either AC or DC. By applying the voltage, a discharge occurred on the surface of the whisker 19, and the discharge continued in a chain reaction, and ultraviolet rays and visible light were generated.

  Next, the generated ultraviolet light photoexcited the particles 11 to emit visible light. Once the discharge is started, the discharge is repeated in a chain reaction, and ultraviolet rays and visible rays are generated. Therefore, in order to suppress the adverse effect on the light emitter 183 by these rays, It is preferable to set it as 50 to 80%. When a voltage of about 0.3 to 1.0 kV / mm was applied with an AC power source or a DC power source, discharge was generated and light emission started. The current value at this time was 0.1 mA or less. Moreover, once light emission started, light emission continued even if the voltage value was lowered. As in the seventh embodiment, high-quality light emission was confirmed for all three colors of blue, green, and red.

  Note that the mechanism of light emission is the same as that in the fourteenth embodiment. In order to efficiently generate discharge and obtain high-quality light emission, a good effect was obtained by executing what is described in Embodiment 14.

  At this time, heat treatment was performed at 450 to 1200 ° C. in air or nitrogen atmosphere for 0.25 to 10 hours to manufacture the light emitter 183, and it was confirmed that a similar light emission phenomenon occurred.

  In the fifteenth embodiment, the coating layer 12 is formed by forming colloidal particles on the surfaces of the inorganic phosphor particles 11 and the insulating fibers 18. That is, it was also confirmed that the colloidal silica aqueous solution or the colloidal alumina aqueous solution used as the binder formed the coating layer 12.

In the above embodiment, a porous structure is provided by using, for example, SiO ₂ —Al ₂ O ₃ —CaO-based insulating fibers. However, a three-dimensional porous structure can be easily formed by using ZnO whiskers. As a result, it becomes easier to generate a discharge, and as a result, the emission intensity is improved.

  Moreover, although Cu was used for the electrode substrate, the resistance value was low and it was not inferior to Al.

(Embodiment 16)
The light-emitting element 1 manufactured in Embodiment Modes 1 to 15 was inserted into a quartz tube and sealed with an inert gas such as Ne, Ar, Kr, or Xe. Thereafter, when a voltage was applied to the light emitting element 1, light emission started at a voltage value of about 0.03 to 0.8 kV / mm. Compared to the case where no inert gas was sealed, the voltage value was reduced by about 60 to 80%, and the light emitting device was further improved in high luminance, high contrast, high recognizability, and high reliability. The reason for this is that by enclosing the inert gas, an electric discharge is more easily generated and an atmosphere in which ultraviolet rays are easily generated is obtained. However, in this case, glow discharge could not be confirmed.

  A flat display is manufactured by arranging the light-emitting elements obtained in Embodiments 1 to 16 in a two-dimensional matrix and turning on and off the applied voltage to each light-emitting element by a driving circuit. can do. This flat display can be realized at a low cost with a simple configuration.

In Embodiments 7 to 14, although the SiO ₂ —Al ₂ O ₃ —CaOO-based composition is used for the insulating fiber 18, Al ₂ O ₃ , SiC, ZnO, TiO ₂ , MgO, BN, Si ₃ N _The same effect can be obtained even if ₄ type fibers are used.
[Industrial applicability]
The light-emitting elements of the present invention can provide an inexpensive flat display device with a simple configuration by two-dimensionally arranging in a matrix.

It is sectional drawing of the light emitting element in Embodiment 1 of this invention. A is a sectional view of the phosphor particles in the first and third embodiments of the present invention, and B is a sectional view of the phosphor particles in the first and third embodiments of the present invention. It is sectional drawing of the light emitting element in Embodiment 2 of this invention. It is sectional drawing of the light emitting element in Embodiment 3 of this invention. It is sectional drawing of the light emitting element in Embodiment 4 of this invention. It is sectional drawing of the light emitting element in Embodiment 5 of this invention. It is sectional drawing of the light emitting element in Embodiment 7 of this invention. It is sectional drawing of the light emitting element in Embodiment 8 of this invention. It is sectional drawing of the light emitting element in Embodiment 9 of this invention. It is sectional drawing of the light emitting element in Embodiment 10 of this invention. It is sectional drawing of the light emitting element in Embodiment 11 of this invention. It is sectional drawing of the light emitting element in Embodiment 12 of this invention. It is sectional drawing of the light emitting element in Embodiment 13 of this invention. It is sectional drawing of the light emitting element in Embodiment 14 of this invention. It is sectional drawing of the light emitting element in Embodiment 15 of this invention. A is a cross-sectional view of a light-emitting element having a light-shielding film formed from the light-emitting body surface side to the inside in Embodiment 7 of the present invention, and B is a cross-sectional view of the light-emitting element having the same groove.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Light emitting element 2, 3 Lead wire 10a, 10b Luminescent body particle 11 Inorganic fluorescent substance particle 12 Coating layer 13,113,123,133,143,153,163,173,183 Light emitting body 14,14a, 14b, 34a, 34b Electrode 15 Through hole 16 Pore 17 Low resistance material 18 Insulating fiber 19 Whisker 20 Light shielding film 21 Inorganic phosphor layer 22 Groove 23 Light emitter layer 30 Substrate 33 Light emitter 40 Metal substrate (electrode)
41 Metal foil

Claims (31)

  A porous illuminant including an insulator having voids and inorganic phosphor particles; and at least two electrodes provided in contact with the surface of the illuminant; applying a voltage to the at least two electrodes; A light emitting element that generates and excites the light emitter by the discharge.   The light emitting device according to claim 1, wherein ultraviolet rays are emitted by the discharge.   The light emitting element according to claim 1, wherein a surface of the porous light emitter is formed of an insulating inorganic material.   The light emitting device according to claim 1, wherein the porous light emitter is formed of an aggregate of inorganic phosphor particles whose surface is coated with an insulating inorganic substance. The insulating inorganic materials are 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 5. The light emitting device according to claim 3, wherein the light emitting device is at least one substance selected from ₂ O _3, PbTiO ₃ , PbZrO ₃ and PBZRTIO ₃ (PZT).   The light emitting device according to claim 1, wherein a through-hole is provided in the light emitter between the electrodes.   The light emitting device according to claim 1, wherein a substance having a resistance lower than that of the insulating metal oxide is dispersed inside the light emitting body between the electrodes.   The light emitting device according to claim 1, wherein the inside of the light emitter is filled with an atmospheric pressure atmosphere or an inert gas.   The light emitting device according to claim 1, wherein the discharge is creeping discharge.   2. The light emitting device according to claim 1, wherein the insulator having the void is at least one selected from a fiber and a foam having open cells.   The light emitting device according to claim 1, wherein the phosphor is obtained by attaching inorganic phosphor particles to the surface of an insulator having the voids.   2. The light emitting device according to claim 1, wherein the insulator having the void is an inorganic substance containing at least one selected from Al, Si, Ca, Mg, Ti, Zn, and B. 3.   The light emitting device according to claim 10, wherein the fiber is obtained by pulverizing an insulating ceramic or glass.   The light emitting device according to claim 10, wherein the fiber is a heat resistant synthetic fiber having a heat distortion temperature of 220 ° C. or higher.   The light emitting device according to claim 1, wherein a substance having a lower resistance than an insulator is dispersed inside the light emitter.   The light emitting device according to claim 1, wherein when the weight of the insulator is 1, the weight of the inorganic phosphor particles is in the range of 0.1 to 10.0.   11. The light emitting device according to claim 10, wherein the fiber has a diameter of 0.1 to 20.0 μm, a length of 0.5 to 100 μm, and an inorganic phosphor particle has an average particle diameter of 0.1 to 5.0 μm.   The light-emitting element according to claim 1, wherein a porosity of the insulator having the void is in a range of 50% to 90%.   A display device in which the light-emitting elements according to any one of claims 1 to 18 are arranged in a matrix.   19. The method for producing the light emitting device according to claim 1, wherein the inorganic phosphor paste is applied to the surface of a plate-like porous body made of an insulator having a void. And a second step of forming a porous light emitter by heat-treating the insulator, and a third step of forming at least two electrodes in contact with the surface of the light emitter. Manufacturing method.   The method of manufacturing a light emitting element according to claim 20, wherein the inorganic phosphor paste contains inorganic phosphor particles whose surfaces are covered with an insulating inorganic substance.   The method for manufacturing a light-emitting element according to claim 21, wherein the coating of the insulating inorganic material is performed by immersing the inorganic phosphor particles in at least one solution selected from a metal complex solution, a metal alkoxide solution, and a colloidal solution, followed by heat treatment. .   The method for manufacturing a light-emitting element according to claim 21, wherein the insulating inorganic substance is coated by attaching the insulating inorganic substance to the surface of the inorganic phosphor particles by any one of vapor deposition, sputtering, and CVD.   After the second step and before the third step, the phosphor is immersed in at least one solution selected from a metal complex solution, a metal alkoxide solution, and a colloidal solution, and then heat treated to coat the surface with an insulating inorganic material. The manufacturing method of the light emitting element of Claim 20.   21. The method for manufacturing a light-emitting element according to claim 20, wherein after the second step and before the third step, an insulating inorganic material is adhered to the surface of the light-emitting body by any one of vapor deposition, sputtering, and CVD.   21. The method for manufacturing a light-emitting element according to claim 20, wherein three types of inorganic phosphor pastes of red, blue, and green are applied in a stripe shape in the first step.   27. The method for manufacturing a light emitting device according to claim 26, wherein a light shielding film or a groove is provided between the inorganic phosphors of different colors.   The method of manufacturing a light emitting device according to claim 20, wherein the inorganic phosphor paste contains a foaming agent.   A method for producing the light emitting device according to claim 1, wherein a paste containing insulating fibers and inorganic phosphor particles is applied on a conductive substrate, and is porous by heat treatment. The manufacturing method of the light emitting element characterized by including the 1st process of forming a quality light-emitting body, and the 2nd process of forming an electrode so that the said light-emitting body surface may be contact | connected.   19. A method for producing a light emitting device according to claim 1, wherein a porous light emitter is formed by molding a paste containing insulating fibers and inorganic phosphor particles and heat-treating the paste. And a second step of forming at least two electrodes in contact with the surface of the light-emitting body.   After the first step, before the second step, the phosphor is immersed in at least one solution selected from a metal complex solution, a metal alkoxide solution, and a colloidal solution, and heat-treated to thereby insulate the surface of the inorganic phosphor particles. The method for producing a light-emitting device according to claim 29 or 30, wherein the light-emitting device is coated with.

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