WO2006008863A1 - Inorganic dispersion electroluminescence element - Google Patents

Abstract

An inorganic dispersion electroluminescence element having a novel structure which suppresses deterioration due to heat and emits light for a long time with high luminance. The inorganic dispersion electroluminescence element is provided with at least a light emitting layer between a pair of electrodes composed of a back plate and a transparent electrode. On a plane opposite to the light emitting layer of the back plate, a ceramic sheet having a thermal emissivity of 0.8 or more and a thickness of 50μm-1,000μm is provided.

Description

 Specification

 Inorganic dispersion type electoluminescence element

 Technical field

 [0001] The present invention relates to an inorganic dispersion-type electroluminescent device.

 Background art

 [0002] Electric mouth luminescence (hereinafter also referred to as "EL") phosphors are voltage-excited phosphors, which are used as inorganic dispersion-type EL devices in which phosphor powders are sandwiched between electrodes. It is known that The general shape of an inorganic dispersion-type EL device is a structural force in which phosphor powder is dispersed in a binder with a high dielectric constant and is sandwiched between two transparent electrodes. Light is emitted by applying an alternating electric field. EL elements made from phosphor powders can be several millimeters or less in thickness, are surface emitters, and have many advantages such as low heat generation, so road signs and various intelligent devices Applications include exterior lighting, light sources for flat panel displays such as liquid crystal displays, and illumination light sources for large-area advertisements.

[0003] Since inorganic dispersion type EL elements do not use a high-temperature process, it is possible to form a flexible element using a plastic substrate, and a relatively simple process without using a vacuum apparatus. It can be manufactured at low cost, and it is easy to adjust the luminescent color of the element by mixing multiple phosphor particles with different luminescent colors, and it can be applied to knock lights and display devices such as LCDs. Has been. However, the range of applications is limited because of the low luminance and efficiency of light emission and the necessity of high voltage of 100V or higher for high-luminance light emission. Sign and display use).

 [0004] In addition, EL devices generally have a problem of generating heat when a voltage is applied. The EL device cannot emit light for a long time due to the accelerated deterioration of heat-sensitive parts (for example, binders in which phosphor powder is dispersed in the case of inorganic dispersion type EL devices) due to heat generation that is weak to heat. .

In order to solve this problem, for example, in Patent Document 1, thermal conductivity is applied to the back surface of the EL element. Discloses a method to dissipate and equalize local heat generation by pasting a graphite sheet with a high level of heat and improve drive life, but it is possible to equalize heat by simply pasting a graphite sheet. The power that is heat dissipation is high!

 [0005] On the other hand, Patent Document 2 discloses a method for improving the heat dissipation effect of a heat sink by forming a film containing sodium silicate and Z or potassium silicate on a heat sink attached to various devices. Yes.

 Patent Document 1: Japanese Patent Laid-Open No. 2003-59644

 Patent Document 2: Japanese Patent Laid-Open No. 2003-309383

 Disclosure of the invention

 Problems to be solved by the invention

[0006] The present invention has been made in order to solve the above-mentioned problems, and an object of the present invention is to provide an inorganic dispersion having a novel structure that can suppress deterioration due to heat generation and emit light with high brightness for a long time. Type EL elements.

 Means for solving the problem

[0007] As a result of intensive studies to solve the above problems, the present inventors can cause the inorganic dispersion type EL element to emit light with high luminance by increasing the applied voltage or increasing the AC frequency. However, it was found that the inorganic dispersion type EL device consumes most of the input power due to heat generation because the light emission efficiency is particularly low in high luminance light emission, that is, the device is greatly deteriorated during high luminance light emission.

 The above problem is solved by an inorganic dispersion EL device having the following specific structure:

 It came to be solved.

 [0008] (1) An organic dispersion type electroluminescent device having at least a light emitting layer between a pair of electrodes such as a back electrode and a transparent electrode, on the surface of the back electrode opposite to the light emitting layer. An inorganic dispersion-type electroluminescent device having a thermal emissivity of 0.8 or more and a thickness of 50 μm to 1000 μm (first embodiment).

(2) An inorganic electroluminescent element having at least a light emitting layer between a pair of electrodes such as a back electrode and a transparent electrode, wherein the back electrode is a graphite sheet Dispersion type electoluminescence element. (3) The inorganic dispersion-type electroluminescent device according to (1), wherein the back electrode is a graphite sheet (second embodiment).

 (4) The inorganic dispersion-type electroluminescent device according to (2) or (3) above, wherein the back electrode has a thermal conductivity of 200 WZm′K or more.

 (5) The deviation of the above (1) to (4), wherein the transparent electrode is a transparent conductive sheet having a transparent conductive film portion and a metal and Z or alloy fine wire structure portion. An inorganic dispersion-type electoluminescence element described in Crab.

 (6) The inorganic dispersion type elect mouth according to any one of (1) to (5) above, wherein the average size of the phosphor particles contained in the light emitting layer is 0.1 to 15 μm Luminescence element.

 The invention's effect

 [0009] According to the present invention, it is possible to provide an inorganic dispersion-type EL element having a novel structure capable of suppressing heat generation and emitting light with high brightness for a long time.

 Brief Description of Drawings

FIG. 1 is an example of an inorganic dispersion-type EL element according to a first embodiment, and is a schematic cross-sectional view.

 FIG. 2 is a schematic cross-sectional view of an inorganic dispersion-type EL element having a moisture-proof film as an example of the inorganic dispersion-type EL element of the first embodiment.

 FIG. 3 is an example of an inorganic dispersion-type EL element according to a second embodiment, and is a schematic plan view.

 FIG. 4 is an example of an inorganic dispersion-type EL element according to a second embodiment, and is a schematic cross-sectional view.

 Explanation of symbols

[0011] 1 Rear electrode

 2 Dielectric layer

 3 Light emitting layer

 4 Transparent electrode

 5 Power supply unit

 6 Moisture-proof film

 7 Light emitter

10 Ceramic sheet 12a ゝ 12b Lead piece

 13a, 13b Lead wire

 BEST MODE FOR CARRYING OUT THE INVENTION

Hereinafter, the inorganic dispersion type EL device of the present invention will be described in detail below. In this specification, “to” is used to mean that the numerical values described before and after it are included as a lower limit value and an upper limit value.

[0013] (First embodiment)

 A first embodiment of the inorganic dispersion-type EL device of the present invention is an inorganic dispersion-type electoluminescence device having at least a light-emitting layer between a pair of electrodes consisting of a back electrode and a transparent electrode. On the opposite side, the thermal emissivity is 0.8 or more and the thickness

It has a ceramic sheet of 50 μm to 1000 μm.

 By placing a ceramic sheet with high thermal emissivity on the surface of the back electrode opposite to the light-emitting layer, the generated heat can be radiated and the life of the inorganic dispersed EL element can be extended. Monkey.

The inorganic dispersion type EL device of the above embodiment is particularly preferable when emitting light with high luminance accompanied by intense heat generation, preferably when emitting light with a luminance of 300 cd / m ² or more, more preferably 500 cd / m ² or more. There is a remarkable heat dissipation effect.

[0014] The inorganic dispersion-type EL device of the first embodiment will be described below with reference to FIGS.

 FIG. 1 is a schematic cross-sectional view showing an example of an inorganic dispersion-type EL element according to the first embodiment. FIG. 2 is a schematic cross-sectional view showing an example of the inorganic dispersion-type EL element of the first embodiment when covered with a moisture-proof film.

The inorganic dispersion-type EL element shown in FIG. 1 has a light emitting portion 7 in which a dielectric layer 2, a light emitting layer 3, and a transparent electrode 4 are laminated in this order on a back electrode 1. In the light emitting unit 7, a conductive power supply unit (pass line) 5 is mounted in an electrically connected state in the vicinity of at least one side of the transparent electrode 4 on the side in contact with the light emitting layer 3. Further, a ceramic sheet 10 excellent in heat radiation is mounted on the back electrode 1. The back electrode 1 and the power supply unit 5 are provided with lead pieces 12a and 12b connected to an AC power source, respectively. Also, lead piece 12a, 12b Are electrically connected to the lead wires 13a and 13b, respectively.

In addition, the light emitting unit 7 or the light emitting unit 7 and the power supply unit 5 may be covered with a moisture-proof film 6 so as to eliminate the influence of humidity from the external environment. FIG. 2 shows an example of the inorganic dispersion type EL element of the first embodiment in which the entire light emitting portion 7 is covered with the moisture-proof film 6. The inorganic dispersion type EL element of the embodiment shown in FIG. 2 has a light emitting portion 7 in which a dielectric layer 2, a light emitting layer 3, and a transparent electrode 4 are laminated in this order on a back electrode 1. In the light emitting unit 7, a conductive power supply unit (pass line) 5 is mounted in an electrically connected state in the vicinity of at least one side of the transparent electrode 4 on the side in contact with the light emitting layer 3. Furthermore, a ceramic sheet 10 having excellent thermal radiation is placed on the back electrode 1 with a moisture-proof film 6 interposed therebetween. The back electrode 1 and the power supply unit 5 are provided with lead pieces 12a and 12b connected to an AC power source, respectively. The lead pieces 12a and 12b are electrically connected to the lead wires 13a and 13b, respectively.

[0017] [Ceramic sheet]

 Hereinafter, the ceramic sheet used in the present invention will be described in detail. The ceramic sheet used in the present invention has a coating film containing sodium silicate and Z or potassium silicate on a substrate.

 The thickness of the ceramic sheet is 50 μm to 1000 μm, preferably 80 μm to 800 μm, more preferably 100 μm to 500 μm. When the sheet thickness is less than 50 μm, the thermal emissivity is lowered, and further, the sheet becomes brittle and the bending strength is lowered. On the other hand, if it exceeds 1000 m, the heat capacity increases, so it is difficult to radiate heat, and it is difficult to bend it, so it is difficult to say that it is flexible.

 Further, the thermal emissivity (JIS A 1423) of the ceramic sheet of the present invention is 0.8 or more, preferably 0.85 or more, more preferably 0.9 or more. From the viewpoint of heat retention, the higher the thermal emissivity, the better.

 Thermal radiation is the heat release due to electromagnetic wave conversion of thermal energy, and the thermal emissivity is a numerical value representing the intensity of infrared rays emitted when an object is heated. 1. Expressed as a ratio when set to 0 (100%).

[0018] Examples of the base material include polyethylene terephthalate, polyethylene naphthalate, and polyetherolate. In addition to flexible polymers such as sulfone, polystyrene, polyethylene, polyarylate, polyether ether ketone, polycarbonate, polypropylene, polyimide, triacetyl cellulose, etc., double-sided adhesive tape such as Sumitomo 3M acrylic soft tape 9894FR-10 It is done.

 [0019] The coating film containing sodium silicate and Z or potassium silicate is particularly preferably a mixture of both sodium silicate and potassium silicate. The coating film can also contain an alkali silicate other than sodium or strong sodium, for example, lithium silicate. This coating film can further contain a metal oxide. As the metal oxide, silicon oxide and aluminum oxide are preferable. Further, the coating film can further contain acid tin. Oxidized tin may be added to sodium silicate and Z or potassium silicate systems, or metal oxides may be added to sodium silicate and Z or potassium silicate systems, and then oxidized tin can be added. You can bark. The metal oxides contained in the coating include aluminum silicate (kaolin), magnesium silicate (talc), silicon oxide, silicon oxide, and tin oxide, as well as titanium oxide, zirconium oxide, and acid oxide. Examples thereof include antimony, acid germanium, boron oxide, calcium oxide, barium oxide, strontium oxide, and acid bismuth.

 [0020] Needless to say, natural minerals such as kaolin and talc containing these metal compounds can also be contained. Further, a metal nitride can be contained. Specific examples of the metal nitride include boron nitride, zirconium nitride, tin nitride, strontium nitride, titanium nitride, and nitride nitride. The metal oxide, metal nitride and the like contained in the coating film in the present invention are preferably used in a fine powder state. In order to make a fine powder, it is preferable to grind with a ball mill, a jet mill or the like.

 [0021] When sodium silicate and potassium silicate are used in combination, the ratio of sodium silicate to potassium silicate is preferably 0.5 to 7 (based on solid content) sodium silicate with respect to potassium silicate 1. The content of alkali silicate in the coating is preferably 3 to 30% by weight. The quantitative ratio of the metal oxide is preferably 12 to 92% by weight in the solid content of the coating film. The ratio of tin oxide to the solid content in the coating film is preferably 6 to 45% by weight.

[0022] The coating material for forming the coating film contains sodium silicate and Z or potassium silicate as basic components. Sodium silicate and potassium silicate are each in the form of an aqueous solution Available at An aqueous solution of sodium silicate is known as water glass. An aqueous solution of sodium silicate and potassium silicate can be used by diluting with water. The aqueous solution containing sodium silicate and Z or potassium silicate is used as a coating material, and coating is performed on the substrate by spraying, applying with a brush, or screen printing. After coating, air dry in the atmosphere. A film forms on the surface of the substrate after air drying. The obtained ceramic sheet exhibits excellent heat dissipation.

 [0023] Further, fine particles of silicon oxide or aluminum oxide can be further added to the coating material for forming the coating film. In this case, the coating liquid becomes a suspension. A ceramic sheet obtained by coating the suspension on the substrate in the same manner exhibits a remarkable heat dissipation effect. Furthermore, fine powder of acid tin can be added. The coating material added with acid tin shows further excellent heat dissipation. Since the coating liquid needs to have an appropriate viscosity, it is preferable to adjust the viscosity of the liquid by adding water as appropriate according to the type and amount of the additive.

 [0024] The inorganic dispersion-type EL element in the first embodiment has a ceramic sheet on the surface opposite to the side having the light emitting layer of the back electrode. The EL element of the above embodiment does not necessarily require a moisture-proof film from the viewpoint of heat dissipation, but as in the embodiment shown in FIG. 2, the entire light emitting unit 7 or the entire light emitting unit 7 and power supply unit 5 Can be mounted on the back electrode 1 with the moisture-proof film 6 sandwiched therebetween. However, from the viewpoint of heat dissipation, it is preferable to mount the electrode so as to be in direct contact with the back electrode.

 Larger area is preferable from the viewpoint of heat dissipation unless there is a restriction on the element design, and the area of the ceramic sheet is not particularly limited, but if the area is too large, the light weight, flexibility, It is not preferable from the viewpoint of the degree of freedom of installation location. The area of the ceramic sheet is preferably 0.7 to 2 times, more preferably 0.9 to 1.5 times the area of the light emitting portion of the inorganic dispersion type EL element.

 There are no particular restrictions on the method of placing the ceramic sheet on the inorganic dispersion-type EL device.For example, there are methods such as attachment with an adhesive, embedding in a moisture-proof film 6, and application to a substrate with grease. .

[0025] The ceramic sheet is provided with a mechanism for cooling the ceramic sheet for the purpose of enhancing the heat dissipation effect. It is also preferable. Specifically, a method of installing a cooling fin on a ceramic sheet, a method of installing an electronic cooling element such as a Bercher element, and the like can be mentioned.

 [0026] [Back electrode]

 Without taking light, the back electrode 1 on the side can be manufactured using any material having conductivity. For example, gold, silver, copper, aluminum, beryllium, connort, chromium, iron, germanium, iridium, potassium, lithium, magnesium, molybdenum, sodium, nickel, platinum, silicon, tin, tantalum, tungsten, zinc, etc. , And graphite sheets, etc., which can be selected as appropriate according to the form of the inorganic dispersion-type EL element to be manufactured and the temperature of the manufacturing process. Among them, it is preferable to use a graphite sheet. This is because the graphite sheet is excellent in electrical conductivity and thermal conductivity, and is lighter and more flexible than metals such as copper, which are generally used as a back electrode, and thus is suitable as an electrode material. In the present invention, it is preferable to use the graphite sheet by acting as a thermal diffusion / radiation sheet just as an electrode! /. By using the graphite sheet as the back electrode, heat generation in the light emitting layer is effectively diffused and dissipated, and light emission with high brightness and long time is possible.

 [0027] The graphite sheet used here is a sheet containing graphite as a main component. In the graphite sheet, carbon atoms are preferably 98.0% by mass or more, more preferably 99.0%. It contains at least 9 mass%, more preferably at least 99.5 mass%.

 Among the above, the graphite sheet used in the present invention is particularly preferably a highly oriented graphite sheet excellent in electrical conductivity and thermal conductivity. Hereinafter, the force S described for the method for producing a highly oriented dullite sheet is not limited to these.

[0028] A highly oriented graphite sheet can be obtained by treating a stretched aromatic imide film at 2600 degrees in an inert gas atmosphere. By stretching the film, it is considered that the aromatic unit force S is oriented parallel to the film surface, and it becomes easier to obtain orientation graphite. As yet another production method, a highly oriented graphite sheet can also be obtained by heating and pressure-curing a mixture of carbon powder and phenol resin in a predetermined shape. The carbon powder here is applicable as long as it contains carbon as a main component, and examples thereof include carbon black, graphite, and charcoal powder. The shape of the carbon powder is particularly limited However, spherical carbon powder is preferred because of its high reliability when forming an element that is easily dispersed uniformly in phenolic resin. As phenol rosin, novolac type and resol type are known depending on the synthesis conditions. Any of the present inventions can be applied.

 [0029] Further, the higher the electrical conductivity of the graphite sheet, the more preferable it is 1000 SZcm or more, and it is more preferable that it is 5000 SZcm or more.

 From the viewpoint of suppressing the temperature rise due to heat generation in the inorganic dispersion type EL device, it is preferable that the thermal conductivity of the graphite sheet is high. Specifically, it is preferably 200 WZm'K or more, more preferably 300. WZm′K or more, more preferably 400 WZm′K or more.

 Further, the thickness of the graphite sheet is preferably 50 m to 5 nm, more preferably 80 / ζ πι to 3 nm, and even more preferably 100 m to lnm! /.

[0030] [Light emitting layer]

 Hereinafter, the light emitting layer will be described.

 The light emitting layer 3 included in the light emitting part 7 is a layer formed by dispersing and containing EL phosphor particles. The EL phosphor particles used in the present invention preferably have an average sphere equivalent diameter of 0.1 to 15 / ζ πι, and more preferably 1 to L0 m. By setting the average average sphere equivalent diameter to the above size, an element capable of emitting light with high luminance can be obtained. The coefficient of variation of the equivalent sphere diameter is preferably 5 to 20%, more preferably 30% or less.

 Here, “sphere equivalent diameter” means the diameter of a sphere when the EL phosphor particle size is converted to a sphere having the same volume as the EL phosphor particle size.

 [0031] As a method for preparing the EL phosphor particles, a firing method, a urea melting method, a spray pyrolysis method, or a hydrothermal method can be preferably used. The prepared EL phosphor particles preferably have a multiple twin structure. For example, when the EL phosphor particles are zinc sulfate, the plane spacing of the multiple twins (stacking defect structure) is preferably 1 to: LOnm, more preferably 2 to 5 nm.

[0032] The EL phosphor particles used in the present invention can be prepared by a firing method (solid phase method) widely used in the art. For example, in the case of zinc sulfate, 10-50 nm particle powder (general This is used as primary particles, and an impure substance called activator is mixed in it and mixed with the flux in a crucible at a high temperature of 900 to 1300 ° C for 30 minutes to 10 hours. 1 is fired to obtain an intermediate fluorescent powder. Next, the obtained intermediate phosphor powder is repeatedly washed with ion-exchanged water to remove alkali metal or alkaline earth metal, excess activator and coactivator. Next, second baking is performed on the obtained intermediate phosphor powder. The second baking is performed at a temperature lower than that of the first baking at 500 to 800 ° C., and the baking time is 30 minutes to 12 hours and the heating (annealing) is performed for a short time.

 [0033] Although many stacking faults are generated in the intermediate phosphor particles by the first and second firings, the first firing is performed so that the particle size is smaller and more stacking faults are included in the particles. And, it is preferable to select the second firing conditions appropriately.

 [0034] By applying an impact force in a certain range to the first fired product, the density of stacking faults without destroying the particles can be greatly increased. As a method of applying an impact force, a method of contacting and mixing intermediate fluorescent particles, a method of mixing and mixing spheres such as alumina (ball mill), a method of accelerating and colliding intermediate phosphor particles, and irradiating ultrasonic waves. A method or the like can be preferably used.

 [0035] According to the above method, in the present invention, particles having 10 or more stacking faults having a stacking fault density of 5 nm or less can be formed. As a method of evaluating the frequency, 10 layers of stacking faults of 5 nm or less were observed when the particles were ground with a mortar and crushed into fragments of thickness of approximately 0.2 m or less with an electron microscope with an acceleration voltage of 200 KV. It can be evaluated by the frequency of the fragment particles contained above. When the particle size is less than 0.2 m, the crushing is not necessary. In order for the device of the present invention to emit light with higher luminance, the above frequency is preferably over 50%, more preferably over 70%. The higher the frequency, the better the narrower the interval.

 [0036] Thereafter, the intermediate phosphor particles are etched with an acid such as HC1 to remove the metal oxides adhering to the surface, and the copper sulfide adhering to the surface is removed by washing with a KCN solution. The Subsequently, the intermediate phosphor is dried to obtain EL phosphor particles.

In the case of zinc sulfide or the like, it is preferable to use a hydrothermal synthesis method as a method for forming phosphor particles because a multiple twin structure is introduced into the phosphor crystal. In hydrothermal synthesis systems, particles Is dispersed in a well-stirred aqueous solvent, and zinc ions and Z or sulfur ions that cause particle growth are added at a flow rate controlled by the reaction vessel external force aqueous solution for a predetermined time. Therefore, in this system, the particles can move freely in an aqueous solvent, and the added ions can diffuse in water and cause particle growth uniformly. For this reason, according to the hydrothermal synthesis method, the concentration distribution of the activator or coactivator inside the particles can be changed, and particles that cannot be obtained by the firing method can be obtained. In addition, in adjusting the particle size distribution, the nucleation process and the growth process can be clearly separated, and the particle size distribution can be adjusted by freely controlling the degree of supersaturation during particle growth. It is possible to obtain powdered zinc oxide particles. An Ostwald ripening step is preferred between the nucleation process and the growth process to adjust the grain size and achieve a multiple twin structure!

 [0038] For example, zinc sulfide crystals have very low solubility in water, which is very disadvantageous when particles are grown by ionic reaction in an aqueous solution. The solubility of zinc sulfide crystals in water increases with increasing temperature, but above 375 ° C, water becomes supercritical and the solubility of ions decreases drastically. Therefore, the particle preparation temperature is preferably 100 to 375 ° C, more preferably 200 to 375 ° C. The time required for particle size adjustment is preferably within 100 hours, more preferably 5 minutes to 12 hours.

 [0039] As another method for increasing the solubility of zinc sulfate in water, a chelating agent is preferably used in the present invention. As chelating agents for Zn ions, those having an amino group or a carboxyl group are preferred. Specifically, ethylenediamine amine acetic acid (EDTA), N-2-hydroxyhexyl ethylenediamine amine acetic acid (EDTA) —OH), diethylenetriaminepentaacetic acid, 2-aminoethylethyleneglycoltetraacetic acid, 1,3-diamino-1-hydroxypropyltetraacetic acid, utilloloacetic acid, 2-hydroxyethyliminodiacetic acid, iminoniacetic acid, 2- Examples thereof include hydroxyschetinoreglicin, ammonia, methinoreamine, ethenoreamine, propylamine, dimethylamine, diethylenetriamine, triaminotriethylamine, allylamamine, ethanolamine and the like.

[0040] In addition, in the case where the constituent metal ion and force Lugogen-on are directly precipitated by using a precipitation reaction without using a precursor of the constituent elements, rapid mixing of both solutions is necessary, and a double jet type mixer is used. Is preferred to use. [0041] It is preferable to use the urea melting method as a method for preparing the phosphor particles used in the present invention. The urea melting method is a method using molten urea as a medium for synthesizing phosphor particles. A substance containing an element that forms a phosphor matrix or an activator is dissolved in a molten liquid in which urea is maintained at a temperature higher than the melting point. Add reactants as needed. For example, when a sulfide phosphor is synthesized, a sulfur source such as ammonium sulfate, thiourea or thioacetamide is added to cause a precipitation reaction. When the temperature of the melt is gradually raised to about 450 ° C., a solid in which phosphor particles and phosphor intermediates are uniformly dispersed in urea-derived resin is obtained. After this solid is finely pulverized, it is fired in the electric furnace while thermally decomposing the resin. By selecting an inert atmosphere, an oxidizing atmosphere, a reducing atmosphere, an ammonia atmosphere, or a vacuum atmosphere as the firing atmosphere, phosphor particles based on oxides, sulfides, and nitrides can be synthesized.

 [0042] It is also preferable to use a spray pyrolysis method as a method for preparing the phosphor used in the present invention. By spray pyrolysis, the precursor solution of the phosphor is made into fine droplets using an atomizer, and phosphor particles are condensed by chemical reaction inside the droplet or chemical reaction with the ambient gas around the droplet. Alternatively, a phosphor intermediate product can be synthesized. By making the conditions for droplet formation suitable, particles with fine particles, homogenous trace impurities, spheroids, and narrow particle size distribution can be obtained. As an atomizer that generates micro droplets, it is preferable to use a two-fluid nozzle, an ultrasonic atomizer, or an electrostatic atomizer. The fine droplets generated by the atomizer are introduced into an electric furnace using a carrier gas and heated to dehydrate and condense, and the chemical reaction and sintering of the substances in the droplets or chemistry with the atmosphere gas The target phosphor particles or phosphor intermediate products are obtained by the reaction. The obtained particles are additionally fired as necessary.

[0043] For example, when synthesizing a zinc sulfide phosphor, a mixed solution of zinc nitrate and thiourea is atomized and thermally decomposed in an inert gas (for example, nitrogen) at a temperature of about 800 ° C. A zinc sulfide phosphor is obtained. If trace impurities such as Mn, Cu and rare earth are dissolved in the starting mixed solution, it acts as a luminescent center. In addition, starting from a mixed solution of yttrium nitrate and europium nitrate at about 1000 ° C in an oxygen atmosphere, an yttrium oxide phosphor activated with europium is obtained. The components in the droplets may contain ultrafine silicon dioxide particles that need not be completely dissolved. Asia Zinc silicate phosphor particles can be obtained by thermal decomposition of micro droplets containing ultrafine particles of lead solution and silicon dioxide.

 [0044] In addition, as a method for preparing the phosphor particles used in the present invention, laser ablation method, CVD method, plasma CVD method, sputtering, resistance heating, electron beam method, fluid oil surface vapor deposition combined method, etc. A phase method, a metathesis method, a method using a precursor thermal decomposition reaction, a reverse micelle method, a method combining these methods with high-temperature firing, a liquid phase method such as a freeze drying method, and the like can also be used. In these methods, phosphor particles having a size of 0.1 to 15 μm that are preferable for the present invention can be obtained by controlling the preparation conditions of the particles.

 [0045] As described in Japanese Patent No. 2756044 and US Pat. No. 6458512, the phosphor particles are non-luminescent composed of a metal oxide or metal nitride of 0.01 m or more. Good waterproofness and water resistance can be imparted by coating with a shell layer. Further, as described in WO02Z080 626, a technique for improving light extraction efficiency by forming a double structure comprising a core portion including a light emission center and a non-light emitting shell portion can be preferably used.

 [0046] The phosphor particles used in the present invention more preferably have a non-light emitting shell layer on the surface of the particles. This non-light-emitting shell layer is formed with a thickness of 0.01 m or more, preferably 0.01 mm or more, using a chemical method following the preparation of the semiconductor fine particles that serve as the core of the EL phosphor particles, preferably 0.01 to Hope to do.

 [0047] The non-light-emitting shell layer can be made of oxide, nitride, oxynitride, or a material force having the same composition formed on the host phosphor particles and containing no emission center. In addition, it is possible to produce material forces of different compositions that are epitaxially grown on the matrix phosphor particle material.

[0048] As a method for forming the non-light-emitting shell layer, a gas-phase method such as a laser one 'abrasion method, a CVD method, a plasma CVD method, a sputtering method, a resistance heating method, an electron beam method, and a fluid oil surface deposition method may be used. , Metathesis method, sol-gel method, ultrasonic chemistry method, precursor thermal decomposition method, reverse micelle method, combined method of these methods and high temperature firing, hydrothermal synthesis method, urea melting method, freeze drying method, etc. Liquid phase methods and spray pyrolysis methods can also be used. Particularly suitable for phosphor particle formation, hydrothermal synthesis, urea melting Methods and spray pyrolysis methods are also suitable for the synthesis of non-luminescent shell layers!

 [0049] For example, when a non-light-emitting shell layer is formed on the surface of zinc sulfide phosphor particles by using a hydrothermal synthesis method, a zinc sulfate phosphor serving as a core particle is added to a solvent, and suspended. Make it cloudy. As in the case of particle formation, a solution containing a metal ion to be a non-light-emitting shell layer material and a cation as required is added from outside the reaction vessel at a controlled flow rate for a predetermined time. By sufficiently stirring the inside of the reaction vessel, the particles can move freely in the solvent, and the added ions can diffuse in the solvent and cause particle growth uniformly. A non-light emitting shell layer can be uniformly formed on the surface. By firing the particles as necessary, zinc sulfide phosphor particles having a non-light emitting shell layer on the surface can be synthesized.

 [0050] Further, when the non-light emitting shell layer is formed on the surface of the zinc sulfide phosphor particles by using the urea melting method, the metal salt as the non-light emitting shell layer material is dissolved and melted in the molten urea solution.亜 鉛 Add zinc phosphor particles. Since zinc sulfate does not dissolve in urea, the temperature of the solution is raised as in the case of particle formation to obtain a solid in which zinc sulfide phosphor and non-luminescent shell layer material are uniformly dispersed in urea-derived resin. . After this solid is finely pulverized, it is fired in an electric furnace while thermally decomposing the resin. By selecting an inert atmosphere, an oxidizing atmosphere, a reducing atmosphere, an ammonia atmosphere, or a vacuum atmosphere as a firing atmosphere, a sulfur having a non-light emitting shell layer such as an oxide, sulfide, or nitride on the surface. Zinc phosphor particles can be synthesized.

 [0051] Further, when the non-light emitting shell layer is formed on the surface of the zinc sulfide phosphor particles by using the spray pyrolysis method, the zinc sulfide is dissolved in a solution in which the metal salt to be the non-light emitting shell layer material is dissolved. Add phosphor. The solution is atomized and pyrolyzed to form a non-luminescent shell layer on the surface of the zinc sulfide phosphor particles. By selecting a pyrolysis atmosphere or an additional firing atmosphere, zinc sulfate phosphor particles having a non-light-emitting shell layer such as an oxide, sulfide, or nitride can be synthesized.

[0052] The matrix material of the EL phosphor particles preferably used in the present invention includes, specifically, one or more elements selected from a group power consisting of Group II elements and Group VI elements, and Group III It is a semiconductor fine particle composed of one or more elements, and the group power composed of elements and group V elements is also selected arbitrarily depending on the required emission wavelength region. For example, CdS, CdSe, CdTe ZnS, ZnSe, ZnTe, CaS, MgS, SrS, GaP, GaAs, and their mixed crystals include ZnS, CdS, CaS, and the like.

[0053] Further, as the base material of the EL phosphor particles, BaAl S, CaGa S, Ga 2 O, Zn SiO

 2 4 2 4 2 3 2

, Zn GaO, ZnGa O, ZnGeO, ZnGeO, ZnAl O, CaGa O, CaGeO, Ca

4 2 4 2 4 3 4 2 4 2 4 3 2

Ge O, CaO, Ga O, GeO, SrAl O, SrGa O, SrP O, MgGa O, Mg GeO

2 7 2 3 2 2 4 2 4 2 7 2 4 2 4

, MgGeO, BaAl O, Ga Ge O, BeGa O, Y SiO, Y GeO, Y Ge O, Y Ge

 3 2 4 2 2 7 2 4 2 5 2 5 2 2 7 4

O, Y 2 O, Y 2 O 3 S, SnO and mixed crystals thereof can be preferably used.

 8 2 3 2 2 2

 [0054] As the activator of the EL phosphor particles used in the present invention, at least one ion selected from copper, manganese, silver, gold and rare earth elements can be preferably used. As the coactivator, at least one kind of ions selected from chlorine, bromine, iodine and aluminum power can be preferably used.

 [0055] As the emission center, metal ions such as Mn and Cr and rare earths can be preferably used.

 [0056] By appropriately selecting the matrix material, activator, and emission center of the EL phosphor particles described above, and using a plurality of phosphor particles, a chromaticity diagram can be used without using dyes or fluorescent dyes. White light emission in the range of 3 <x <0.4 and 0.3 <y <0.4 can be substantially obtained.

 [0057] The light emitting layer 3 can be formed by dispersing the above-described phosphor particles in a dispersant. Examples of the dispersant used to disperse the phosphor particles in the light emitting layer 3 include polymers having a relatively high dielectric constant such as cyanoethyl cellulose resin, polyethylene, polypropylene, polystyrene resin, A silicone resin, an epoxy resin, a rubber beidene, or the like can be used. Moreover, BaTiO and SrTiO

 The dielectric constant can be adjusted by mixing fine particles with a high dielectric constant such as 3 3. As a dispersing method of the dispersant, a homogenizer, a planetary kneader, a roll kneader, an ultrasonic disperser, or the like can be used. In order to emit light with high brightness, the weight ratio of the particles to the dispersing agent in the light emitting layer is preferably 5.0 to 20.

[0058] In order to obtain high luminance, it is preferable that the thickness of the light-emitting layer 3 is 1 to 60 μm, and it is more preferable that the thickness is 3 to 50 / ζ πι. The light emitting layer 3 emits light when the variation in the distance between the back electrode 1 and the transparent electrode 4 described later is viewed as the centerline average roughness Ra. The surface of the optical layer 3 preferably has a smoothness of (dXlZ8) or less with respect to the thickness d of the light emitting layer 3.

[0059] [Dielectric layer]

 The inorganic dispersion type EL device of the present invention can be formed by adjoining the light emitting layer 3 with the dielectric layer 2 containing an inorganic dielectric substance, if necessary. As the inorganic dielectric substance, any material can be used as long as it has a high dielectric constant and insulation and a high dielectric breakdown voltage. As the inorganic dielectric material, various metal oxides and nitrides can be used. For example, SiO, TiO, BaTiO, SrTiO, PbTiO, KNbO, PbNbO, Ta O

 2 2 3 3 3 3 3 2 3

BaTa 2 O, LiTaO, Y 2 O, Al 2 O 3, ZrO, A10N, ZnS, and the like can be used.

 2 6 3 2 3 2 3 2

 These can be used alone or in combination. The dielectric layer 2 may be formed as a uniform film or may be formed as a film having a particle structure. Furthermore, the dielectric layer 2 may be a single layer or a laminate of different insulating layers.

 [0060] The dielectric layer 2 may be either a thin film crystal layer structure or a particle shape structure, or a combination thereof. The dielectric layer 2 may be provided only on one side of the light emitting layer 3 as shown in FIG. 2, but is preferably provided on both sides of the light emitting layer 3 from the viewpoint of obtaining high luminance. When the dielectric layer 2 has a thin film crystal layer structure, it may be a thin film formed on a substrate by a vapor phase method such as sputtering, or a sol-gel film using an alkoxide such as Ba or Sr. Further, when the dielectric layer 2 has a particle shape structure, it is preferable that the size of the dielectric material is sufficiently smaller than the phosphor particle size. Specifically, it is preferable that the particles of the dielectric substance have an average particle size of the phosphor particles of 1Z3 ~: LZ100 00! / ,.

 [0061] The inorganic dispersion-type EL device of the present invention has a structure having a light emitting layer containing a phosphor material sandwiched between a pair of opposing electrodes, at least one of which is transparent. Therefore, the total thickness (hereinafter also referred to as “element thickness”) of the light emitting layer 3 and the dielectric layer 2 described above is to ensure the smoothness of the force element having a size equal to or larger than the average diameter of the EL phosphor particles. The element thickness is preferably 1.1 to 10 times that of the average sphere equivalent diameter of the EL phosphor particles. It is preferably 2 to 10 times and more preferably 3 to 5 times. Is more preferable.

[0062] Further, the dielectric layer 2 is formed so as to cover a part of the upper part of the particle, that is, on a part of the light emitting layer 3. It is preferable because the effect of increasing the contact point or improving the smoothness of the device surface appears by coating it so that it can be placed on the surface.

 [0063] The dielectric substance contained in the dielectric layer 2 and the phosphor particles contained in the light emitting layer 3 can be in direct contact with the dielectric substance, but the dielectric substance It is preferred to contact the phosphor particles that are fully or partially covered with a non-luminescent shell layer. Further, the contact between the dielectric material and the phosphor material may be merely contact, but the upper part of the phosphor particles may be completely or partially covered, that is, the light emitting layer 3 is entirely covered with the dielectric layer 2. If there is a contact between the light-emitting layer 3 and the dielectric layer 2 in contact with the light-emitting layer 3, the contact point increases and the device A viewpoint power capable of developing effects such as improving the smoothness of the surface is also preferable.

 [0064] The dielectric layer 2 and the light emitting layer 3 are preferably formed by application using a spin coating method, a dip coating method, a bar coating method, a spray coating method, or the like. In particular, it is preferable to use a method that does not select a printing surface, such as a screen printing method, or a method that allows continuous application, such as a slide coating method. For example, in the screen printing method, a dispersion liquid in which phosphor or dielectric fine particles are dispersed in a polymer solution having a high dielectric constant is applied through a screen mesh. The film thickness can be controlled by appropriately selecting the thickness of the screen mesh, the aperture ratio, and the number of coatings. By adjusting the dispersion, not only the dielectric layer 2 and the light-emitting layer 3 but also the back electrode 1 can be formed, and the large area can be easily obtained by changing the size of the screen mesh. The method for preparing the dielectric layer 2 may be a vapor phase method such as a sputtering method or a vacuum deposition method. In addition, by coating the dielectric layer 2 so that the portion of the dielectric layer 2 is placed on a part of the light emitting layer 3, the contact points between the phosphor particles and the dielectric material can be increased, and the smoothness of the EL element can be further improved. It is preferable because an effect such as improvement can be obtained.

 [0065] [Transparent electrode]

The transparent electrode 4 can be formed of any commonly used transparent electrode material. Examples of such transparent electrode materials include tin-doped tin oxide, antimony monophosphate tin, zinc-doped tin oxide, tin-doped indium (ITO), and other oxides, and silver thin films with a high refractive index. Examples include multilayer structures sandwiched between layers, and π-conjugated polymers such as polyarine and polypyrrole. Transparent electrodes include polyethylene terephthalate (PET) and polyethylene naphthalate It can be formed by providing a transparent conductive film formed of the above transparent electrode material on a substrate made of a transparent sheet such as (PEN).

 [0066] The resistance value of the transparent conductive sheet preferably used as the transparent electrode 4 preferably has a surface resistivity of 0.05 to 50Ω in view of uniformity of luminance on the light emitting surface. More preferably, it is 1 to 30Ω.

 [0067] The method for preparing the transparent electrode 4 may be any of a sputtering method and a vapor phase method such as vacuum deposition. However, there is a case where these cannot be sufficiently low resistance alone. In that case, for example, it is preferable to improve the conductivity by arranging a mesh-like metal such as a comb type or a grid type, and a thin wire of an iron or alloy.

 Copper, silver, and aluminum are preferable as the fine wires of metals and alloys, but depending on the purpose, the above-mentioned transparent electrode material used in the formation of a transparent conductive film can be used for high electrical conductivity and thermal conductivity. Preferred to be a material ,. The thickness of the thin wire of the metal and metal or alloy is arbitrary, but is preferably between 0.1 m and 100 μm. It is particularly preferred that the thin wires are arranged at a pitch of 50 μm to 1000 μm, with a pitch of 100 μm to 500 μm being particularly preferred. The light transmittance is reduced by arranging metal and Z or alloy fine wires, but it is important to keep the reduction as small as possible, and the interval between the fine wires is made too narrow and the width and height of the fine wires are increased. It is important to ensure a transmittance of 90% or more and less than 100% without taking too much.

 Preferably, the shape of the thin line is a square mesh shape, a rectangular mesh shape, or a rhombus mesh shape. The width of the fine line may be determined according to the purpose, but typically, the fine line interval is preferably 1Z10000 or more and 1Z10 or less.

 The height of the fine wire is the same. The range of 1Z100 to 10 times the width of the fine wire is preferably used.

 As a method for forming a transparent electrode having a transparent conductive film portion and a fine wire structure portion of metal and Z or an alloy, the fine wire may be bonded to a transparent conductive sheet, or on a mesh-like fine wire formed on the sheet. A transparent electrode material such as ITO may be applied and evaporated.

[0068] [Power Supply Unit]

The power supply unit 5 is a conductive bus line electrically connected to the transparent electrode 4, for example, As shown in FIGS. 1 and 2, the light emitting layer 3 and the transparent electrode 4 can be mounted on at least one side of the light emitting layer 3. The power supply unit 5 can also be placed on at least one side of the transparent electrode 4. The power supply unit 5 can be formed of a printed layer of a conductive paste such as silver paste or carbon paste, for example. Also, gold, silver, copper, aluminum, beryllium, cobalt, chromium, iron, germanium, iridium, potassium, lithium, magnesium, molybdenum, sodium, nickel, platinum, silicon, tin, tantalum, tandastene, zinc, It can also be formed from a metal such as a graphite sheet, or an alloy or inorganic material thereof. When the power supply unit is mounted as in the embodiment shown in FIG. 1 and FIG. 2, the lead piece 12a and the power supply unit 5 described later can be integrally manufactured.

 On the other hand, it is possible to place the power supply portion on the back electrode 1 on at least one side of the back electrode 1 between the back electrode 1 and the dielectric layer 2.

 [0069] In this specification, the term "installed in the vicinity of the side" means that the element side length is about 1Z100 to 1Z10, as well as the case where the element side is completely matched with each side of the element. It also includes the case of mounting at the center side position.

 [0070] The length of the power supply unit 5 in the longitudinal direction and the width direction can be appropriately determined according to the size of the designed inorganic dispersion-type EL element. For example, in the case of the inorganic dispersion-type EL element of the embodiment shown in FIG. 2, the length of the power supply unit 5 in the longitudinal direction can be substantially the same as the length of the element side in the longitudinal direction of the power supply unit 5.

 [0071] [Moisture-proof film]

 In the inorganic dispersion type EL device of Embodiment 1, as shown in the embodiment of FIG. 2, the light emitting part 7 or the light emitting part 7 and the power supply part 5 are covered with a moisture-proof film 6 so as to eliminate the influence of humidity from the external environment. Can do. If the light-emitting unit 7 itself has sufficient shielding properties against humidity, a shielding sheet is placed over the formed light-emitting unit 7 or the light-emitting unit 7 and the power supply unit 5, and the periphery is a cured material such as epoxy. Seal with. Such a shielding sheet is selected from metal and plastic film according to the purpose.

[0072] From the viewpoint of lightness, flexibility, and flexibility in installation location, the moisture-proof film 6 is preferably made of a lightweight and highly flexible material such as a resin film. Moisture-proof film 6 is a transparent film with a low water-moisture permeability, such as a polychlorinated trifluoroethylene film. A film can be used. The moisture-proof film 6 is formed by sandwiching the entire light-emitting part 7 or the light-emitting part 7 and the power-supplying part 5 between two sheets and applying heat and roll pressure to seal the protruding part of the sheet. 7 and the power supply part 5 can be sealed.

 [0073] When the light-emitting part 7 or the light-emitting part 7 and the power supply part 5 are sealed with the moisture-proof film 6, in order to prevent moisture absorption of the light-emitting part 7 with the passage of time, between the transparent electrode 4 and the moisture-proof film 6, It is preferable to provide a hygroscopic layer (not shown) integrally. For the hygroscopic layer, a hygroscopic film such as a 6-knife film can be used.

 [0074] [Lead piece and lead wire]

 In the inorganic dispersion-type EL element of the first embodiment, the lead wires 13a and 13a electrically connected to the back electrode 1 and the transparent electrode 4 for the purpose of applying an alternating electric field to the back electrode 1 and the transparent electrode 4 and 13b is disposed. The lead wires 13a and 13b are electrically connected to the back electrode 1 and the transparent electrode 4 through lead pieces 12a and 12b, respectively. However, when the power supply unit 5 is provided between the transparent electrode 4 and the light emitting layer 3, the lead piece 12a and the power supply unit 5 are electrically connected. From the viewpoint of high luminance emission of the inorganic dispersion type EL element, it is preferable that the lead pieces (12a, 12b) and the lead wires (13a, 13b) have high electrical conductivity. Furthermore, from the viewpoint of electrical conductivity, the lead piece and the lead wire (12a and 13a, 12b and 13b), the lead piece 12a and the transparent electrode 4 or the power supply section 5, and the lead piece 12b and the back electrode 1 are integrated. It is preferable to produce it.

 Specifically, for example, when the back electrode 1 of the present invention made of a graphite sheet and the lead piece 12b are produced integrally, the graphite sheet is cut out to produce a back electrode having a lead piece portion. By using this, the back electrode and the lead piece can be integrated together.

[0075] From the viewpoint of heat dissipation, it is preferable that the lead pieces 12a and 12b have high thermal conductivity.

 Specifically, it is preferable that the thermal conductivity of the lead piece is equal to or greater than lOOWZm′K, and more preferably equal to or greater than 200W Zm′K.

Preferred materials include metals selected from gold, silver, copper, aluminum, beryllium, iridium, potassium, magnesium, molybdenum, sodium, silicon, tungsten, zinc, graphite sheets, and alloys and inorganics thereof. Can be more preferred Examples of such materials include metals such as gold, silver, copper, aluminum, beryllium, and graphite sheets, and alloys and inorganic substances thereof.

 [0076] In particular, from the viewpoint of increasing the thermal conductivity in the portion where the lead piece 12b is attached to the back electrode 1 and the portion where the lead piece 12a is attached to the transparent electrode 4 or the power supply portion 5, power is supplied onto the transparent electrode 4. Part 5 is preferred.

 [0077] From the standpoint of further increasing the thermal conductivity, the power supply section 5 and the lead piece 12a mounted on the transparent electrode 4 and the back electrode 1 and the lead piece 12b are each integrally formed. Is more preferable. It is more preferable that these and the lead wires 13a and 13b are manufactured integrally.

 [0078] [Production method]

 Next, a method for manufacturing the EL element of the first embodiment will be described.

 The EL device of the first embodiment can be manufactured by the process of forming the light emitting portion 7 having the light emitting layer 3 between the transparent electrode 4 and the back electrode 1, and in the case shown in FIG. In addition to the above steps, the step of mounting the power supply unit 5 on the transparent electrode 4, the step of mounting the lead piece 12b on the back electrode 1, the lead piece 12a on the transparent electrode 4 or the power supply unit 5 A step of electrically connecting the lead wires 13a, 13b to the lead pieces 12a, 12b, and a step of mounting the ceramic sheet 10 on the back electrode 1. it can.

 In addition, as shown in FIG. 2, it may have a step of covering the entire light emitting unit 7 or the entire light emitting unit 7 and the power supply unit 5 with the moisture-proof film 6. Although the ceramic sheet 10 may be affixed to the rear electrode 1, it is preferable that the ceramic sheet 10 is directly adhered to the rear electrode 1 and then covered with the moisture-proof film 6 from the viewpoint of heat dissipation.

 [0079] In the step of forming the light-emitting portion 7, the dielectric layer 2 and the light-emitting layer 3 are formed on the back electrode 1 in a desired shape by using a spin coat method, a dip coat method, a bar coat method, or a spray coating method. Can be produced by laminating the transparent electrode 4 on which the power supply unit 5 is mounted.

[0080] In the step of mounting the lead piece 12a, the light emitting unit 7 or the light emitting unit 7 and the power supply unit 5 are The terminal piece 12a is attached in a state of being electrically connected to the transparent electrode 4 or the power supply unit 5. In the process of mounting the lead wire 13a, the lead wire 13a is attached in a state where it is electrically connected. It is preferable that the lead piece 12a is manufactured integrally with the power supply unit 5, and it is more preferable that the lead wire 13a is integrated.

 If the light-emitting part 7 or the light-emitting part 7 and the power-supply part 5 are covered with the moisture-proof film 6, the light-emitting part is formed by the moisture-proof film 6 with the lead piece 12 b electrically connected to the back electrode 1. 7 or the light emitting unit 7 and the power supply unit 5 can be covered entirely.

 In the step of mounting the lead wire 13b, the lead wire 13b is attached in a state where it is electrically connected. It is preferable that the lead piece 12b is integrally formed with the back electrode 1, and it is further preferable that these are integrated with the lead wire 13b.

[0081] (Second Embodiment)

 The inorganic dispersion-type EL element according to the second embodiment of the present invention is an inorganic dispersion-type electroluminescent device having at least a light-emitting layer between a pair of electrodes having a back electrode and a transparent electrode. The back electrode is a graphite. It is a sheet. The graphite sheet acts not only as an electrode but also as a thermal diffusion and heat dissipation sheet.

The inorganic dispersion-type EL device of the second embodiment is particularly effective when emitting high-intensity light with strong heat generation, preferably when emitting light with a luminance of lOOcdZm ² or more, more preferably 300 cd / m ² or more. It has remarkable heat diffusion and heat dissipation effects.

FIG. 3 and FIG. 4 show an example of an inorganic dispersion-type EL element according to the second embodiment in which the entire light-emitting portion 7 is covered with the moisture-proof film 6 (FIG. 3 is a schematic plan view, FIG. 4). Is a schematic cross-sectional view). The inorganic dispersion type EL element of the embodiment shown in FIGS. 3 and 4 has a light emitting portion 7 in which a dielectric layer 2, a light emitting layer 3, and a transparent electrode 4 are laminated in this order on a back electrode 1. In the light emitting part 7, a conductive power supply part (pass line) 5 is placed in an electrically connected state at least near one side of the transparent electrode 4 on the side in contact with the light emitting layer 3. The back electrode 1 and the power supply unit 5 are provided with lead pieces 12a and 12b connected to an AC power source, respectively. The lead pieces 12a and 12b are electrically connected to the lead wires 13a and 13b, respectively. [0083] As the graph eye sheet used as the back electrode in the second embodiment, the graph eye sheet described in the first embodiment can be used. In addition, the other members such as the light emitting layer, the back electrode, and the transparent electrode can be the same as those described in the first embodiment.

 [0084] [Production method]

 Next, a manufacturing method of the inorganic dispersion type EL display element of the second embodiment will be described. The EL display element according to the second embodiment includes a step of forming a light-emitting portion 7 having a light-emitting layer 3 between the transparent electrode 1 and the back electrode 4, and a step of mounting a power supply portion 5 on the transparent electrode 4. The lead piece 12b is placed on the back electrode 1, the lead piece 12a is placed on the transparent electrode 4 or the power supply section 5, and the lead wires 13a and 13b are electrically connected to the lead pieces 12a and 12b. And the step of covering the entire light-emitting part 7 or the entire light-emitting part 7 and the power supply part 5 with the moisture-proof film 6.

 [0085] In the step of forming the light-emitting portion 7, the dielectric layer 2 and the light-emitting layer 3 are formed on the back electrode 1 in a desired shape by using a spin coat method, a dip coat method, a bar coat method, or a spray coating method. Can be produced by laminating the transparent electrode 4 on which the power supply unit 5 is mounted.

 In the step of mounting the lead piece 12a, the lead piece 12a is attached to the light emitting unit 7 or the light emitting unit 7 and the power supply unit 5 in a state of being electrically connected to the transparent electrode 4 or the power supply unit 5. In the process of placing the lead wire 13a, the lead wire 12a is attached in an electrically connected state. It is preferable that the lead piece 12a is integrally formed with the power supply unit 5, and it is more preferable that the lead piece 13a is integrated with the lead wire 13a. The lead piece 12b can be covered with the moisture-proof film 6 while covering the light emitting part 7 or the light emitting part 7 and the power supply part 5 in a state where the lead piece 12b is attached in a state of being electrically connected to the back electrode 1. In the step of mounting the lead wire 13b, the lead wire 13b is attached in a state where it is electrically connected. It is preferable that the lead piece 12b is manufactured integrally with the back electrode 1, and it is more preferable that the lead wire 13b is integrated with these.

 [0087] [Usage]

The light emission color of the inorganic dispersion EL element used in the present invention is considered as a light source. The white color is preferred. Specific methods for setting the emission color to white include, for example, a method using phosphor particles that emit white light alone, such as a ZnS phosphor activated with manganese and gradually cooled after firing, and three primary colors Alternatively, it is preferable to use a method of mixing a plurality of phosphors that emit light of complementary colors (for example, a combination of blue, green, and red, or a combination of blue, green, and orange). In addition, light is emitted at a short wavelength such as blue as described in JP-A-7-166161, JP-A-9-245511, and JP-A-2002-62530, and light is emitted using a fluorescent pigment or fluorescent dye. It is also preferable to use a method of converting a part of the light into green or red and then whitening it. Furthermore, the CIE chromaticity coordinates (X, y) are preferably in the range of the X value force SO. 30 to 0.40 and the force y value force SO. 30 to 0.40.

[0088] Usually, the inorganic dispersion type EL element is driven by an alternating current, and is typically driven by using an alternating current power source of 100V and 50 to 400Hz. When the area of the inorganic dispersion-type EL element is small, the luminance increases almost in proportion to the applied voltage and frequency. However, in the case of an inorganic dispersion type EL element having a large area of 0.25 m ² or more, the capacitance component of the inorganic dispersion type EL element increases, and there is a deviation between the inorganic dispersion type EL element and the impedance matching of the power source. The time constant required for the charge stored in the device may increase. For this reason, large-area inorganic dispersion-type EL elements may have insufficient power supply even at higher voltages, especially at higher frequencies. In particular, in the case of an inorganic dispersion type EL element having a large area of 0.25 m ² or more, for AC driving of 500 Hz or more, the applied voltage often decreases as the driving frequency increases, resulting in lower brightness. Often happens.

In contrast, since the inorganic dispersion type EL element of the present invention can suppress deterioration of the element due to heat generation, even at a size of 0.25 m ² or more, driving at a higher frequency than normal, preferably driving at 500 Hz to 5 KHz, Preferably, driving at 800 Hz to 4 KHz is possible, and high brightness can be obtained.

 The inorganic dispersion-type EL element of the present invention can be used as, for example, a knock light for a backlight display film for ink jet recording on which an image is recorded by an ink jet recording method.

In addition, the inorganic dispersion type EL device of the present invention has, for example, a high image quality with a maximum density of 1.5 or more. It can also be used as a backlight for transparent print images, and can realize high-quality, large-area advertisements and the like.

 Example

 [0090] Specific examples of the inorganic dispersion-type EL device of the present invention are described below, but the present invention is not limited to these examples.

[0091] (First embodiment)

 <Example 1 1>

Phosphor particles having an average particle size of 25 μ m (ZnS; Cu, CI) and mean particle size of red Pigment is 4 mu m (Shinroihi FA- 001, manufactured by Shinroihi Ltd.) 30 mass and _^0/0 Shiano Dispersed in an ethyl cellulose solution to obtain a light emitting layer paste. Further, barium titanate powder having an average particle size of 0.2 m was uniformly dispersed in 30% by mass of cyanoethyl cellulose solution to obtain a dielectric paste.

 The above dielectric paste is applied on an aluminum sheet (thickness 75 m, thermal emissivity 0.04, thermal conductivity 180 WZm'K) so that the film thickness after drying is 35 / zm. And dried at 110 ° C for 4 hours. Further, the above light emitting layer paste was applied on this so that the film thickness after drying was 35 μm, and dried at 110 ° C. for 6 hours by a hot air dryer.

 Next, using a sheet of ITO uniformly deposited to a thickness of lOOnm by sputtering on polyethylene terephthalate with a thickness of 100 m as a transparent electrode, silver paste is printed on the conductive surface side of the sheet as a power line by screen printing, After drying, a lead electrode made of a lead piece made of a copper aluminum sheet was attached.

 In addition, a lead electrode made of a copper aluminum sheet is attached to the side opposite to the coated surface of the aluminum sheet, and then the coated surface of the aluminum sheet and the conductive surface of the transparent conductive sheet are bonded together. And thermocompression bonded. Further, a ceramic sheet (“First to paste first” made by Ceramission, thermal emissivity; 0.96, sheet thickness 30 O / zm) was pasted on the side opposite to the coated surface of the aluminum sheet. The size of the light emitting surface of the element was set to 500 mm X 500 mm.

 <Example 1 2>

Instead of the above aluminum sheet, Graphite Sheet ("PGS Graphite Sheet" Matsushita Electronics The procedure was the same as Example 1-1, except that a component manufactured and a thermal conductivity of 800 WZm'K) was used.

 <Example 1 3>

 A thin copper wire with a width of 5 microns and a height of 2.5 microns is deposited on polyethylene terephthalate with a thickness of 100 microns by vacuum deposition to form a square with an interval of lmm, and then ITO is sputtered to 30 nm. The same procedure as in Example 1-1 was performed, except that a sheet having a uniform thickness was used as the transparent electrode.

[0094] <Example 1-4>

 The same procedure as in Example 1-1 was performed, except that phosphor particles (ZnS: Cu, C1) having an average particle size of 10 / zm were used to produce a light emitting layer paste.

<Example 1 5>

 A thin copper wire with a width of 5 microns and a height of 2.5 microns is deposited on polyethylene terephthalate with a thickness of 100 microns by vacuum deposition to form a square with an interval of lmm, and then ITO is sputtered to 30 nm. The same procedure as in Example 1-4 was performed, except that a sheet having a uniform thickness was used as the transparent electrode.

[0096] <Example 1-6>

 The same procedure as in Example 15 was performed, except that a graphite sheet (“PGS graphite sheet” manufactured by Matsushita Electronic Components, thermal conductivity: 800 WZm. K) was used instead of the above aluminum sheet. O

 [0097] <Comparative Example 1 1>

 The same procedure as in Example 1-1 was performed except that the ceramic sheet was not attached to the aluminum sheet.

 [0098] <Comparative Example 1 2>

 Except that the graphite sheet (“PGS Graphite Sheet”, manufactured by Matsushita Electronic Components, thermal conductivity: 800 WZm. K, thermal emissivity: 0.75) was attached to the aluminum sheet, the same procedure as in Example 1-1 was performed. It was.

[0099] <Comparative Example 1 3>

Except for sticking ceramic sheet (thermal emissivity 0.5, thickness 40 μm) to aluminum sheet, The same procedure as in Example 1-1 was performed.

[0100] Under the driving conditions of voltage 200V and frequency ΙΚΗζ, the EL display panels of Examples 1 to 16 and Comparative Example 1 1 and 13 were driven in an environment of 20 ° C and 60% humidity. The luminance of each was 600 cd / m ² . Furthermore, Table 1 shows the relative luminance with respect to the initial luminance when these devices are driven continuously for 300 hours under the same environment.

[0101] [Table 1]

Compared to Comparative Example 1 and 1, using a ceramic sheet on the surface of the back electrode opposite to the light-emitting layer as in Examples 1 1 and 1 2 improves heat dissipation and increases the relative luminance after time. did. In addition, the effect was increased by changing the back electrode to a graphite sheet. Compared with Comparative Example 1-2, it was found that the effect of the ceramic sheet application was greater than that of the graphite sheet application. Particularly in Example 1-2, since the back electrode is a graphite sheet, the local heat of the light emitting layer is soaked and further radiated by the ceramic sheet, so that the effect is remarkable.

 Also, in contrast to Example 1-1, changing the transparent electrode from ITO to copper fine wire + ITO as in Example 1-3 can improve not only the deterioration of ITO but also the heat dissipation from the transparent electrode, Furthermore, the change in relative luminance after time was small.

 When the average particle size of the phosphor particles was reduced as in Example 14 and the calorific value was increased, as a result, the heat dissipation effect was enhanced and the life was improved compared to Example 1-1.

 Furthermore, in contrast to Example 14, good results were obtained by changing the transparent electrode to copper fine wire + ITO as in Example 15. In Example 1-6, when the back electrode was changed to a graphite sheet from Example 1-5, a further heat radiation effect was obtained, and the best result was obtained.

 As in Comparative Example 13 and 3, even if the ceramic sheet had a thermal emissivity of less than 0.8 and a sheet thickness of less than 50 m, the heat dissipation effect was not obtained.

(Second Embodiment) <Example 2-1>

Phosphor particles having an average particle size of 25 μ m (ZnS; Cu, CI) and red Pigments having an average particle diameter of 4 mu m (Shinroihi FA- 001, Shinroihi Co. (Ltd.)) and a 30 weight _^0/0 It was dispersed in a cyanoethyl cellulose solution to obtain a light emitting layer paste. Also Xia Bruno ethylcellulose solution of 30 weight _^0/0 uniformly dispersed barium titanate powder having an average particle diameter of 0. 2 m, and the dielectric paste.

 The above dielectric paste is applied on a graphite sheet (PGS graphite sheet (thermal conductivity; 800 W / mK), manufactured by Matsushita Electronic Components Co., Ltd.) to a film thickness of 35 μm, and a hot air dryer And dried at 110 ° C for 4 hours. Further, the above light emitting layer paste was applied to a thickness of 35 μm, and dried at 110 ° C. for 6 hours with a hot air dryer.

Next, using a sheet of ITO uniformly deposited to a thickness of lOOnm by sputtering on polyethylene terephthalate with a thickness of 100 m as a transparent electrode, silver paste is printed on the conductive surface side of the sheet as a power supply line by screen printing. Dry and made of copper aluminum sheet A lead electrode made of a piece was attached.

 The coated surface of the graphite sheet and the conductive surface of the transparent conductive sheet were bonded together and thermocompression bonded to obtain an inorganic dispersion-type electroluminescent device.

 The size of the light emitting surface of the device was set to 500 mm X 500 mm.

[0104] Example 2-2->

 The test was performed in the same manner as in Example 2-1, except that the graphite sheet was changed to Super E GS (thermal conductivity: 350 W / m'K, manufactured by Suzuki Sogo Co., Ltd.).

[0105] Example 2-3—

 A thin copper wire with a width of 5 / zm and a height of 2.5 m was deposited on a polyethylene terephthalate with a thickness of 100 / zm by vacuum deposition to form a square with a spacing of lmm, and ITO was further deposited on the surface by a notch. The same procedure as in Example 2-1 was performed except that a sheet uniformly adhered to a thickness of 30 nm was used as the transparent electrode.

[0106] Examples 2-4>

 The same procedure as in Example 2-1 was performed, except that phosphor particles (ZnS: Cu, C1) having an average particle diameter of 10 / zm were used and a light emitting layer paste was prepared.

[0107] Example 2-5>

 A thin copper wire with a width of 5 / zm and a height of 2.5 m was deposited on a polyethylene terephthalate with a thickness of 100 / zm by vacuum deposition to form a square with a spacing of lmm, and ITO was further deposited on the surface by a notch. The same procedure as in Example 2-4 was performed except that a sheet uniformly adhered to a thickness of 30 nm was used as the transparent electrode.

[0108] <Comparative Example 2-1>

 Performed in the same manner as in Example 2-1, except that an aluminum sheet was used instead of the graphite sheet o

 [0109] <Comparative Example 2-2>

 On the back side of the aluminum sheet (surface opposite to the light emitting layer of the back electrode)

The procedure was the same as Comparative Example 2-1, except that a GS graphite sheet (thermal conductivity; 800 WZm'K, manufactured by Matsushita Electronic Components Co., Ltd.) was placed.

[0110] Examples 2-1 to 2-5 and Comparative Example 2— under the driving conditions of voltage 200V and frequency ΙΚΗζ When the 1 and 2-2 EL display panels were driven in an environment with an air temperature of 20 ° C and a humidity of 60%, the initial luminance was 600 cd / m ² . Furthermore, Table 2 shows the luminance half-life (drive time required for the EL luminance to drop to half of the initial luminance) when these elements are driven continuously in the same environment.

[Table 2]

(Table 2)

 Back electrode of phosphor particles

 Transparent electrode Luminance half-life Type Thermal conductivity Average particle size

Example 2— 1 Graphite sheet 800 W / mK 25 U m ITO 500 hours Example 2— 2 〃 350 W / mK II II 420 hours Example 2— 3 〃 800 W / mK II copper wire + ITO 600 hours Example 2— 4 // // 10 m ITO 520 hours Example 2— 5 〃 〃 銅 Copper wire + ITO 550 hours Comparative Example 2-1 Aluminum sheet 237 W / mK 25 m ITO 200 hours On the back of the aluminum sheet

 237 W / m-K

Comparative Example 2—2 Affixing the Graph Eye Sheet 〃 〃 280 hours

 (800 W / m-K)

Date

[0112] Compared to Comparative Example 2-1 in which the back electrode is an aluminum sheet, heat dissipation is improved by making the back electrode a graphite sheet as in Examples 2-1 and 2-2, and the luminance half-life is increased. Increased. In particular, Example 2-1 exhibited a remarkable effect because of the high thermal conductivity of the back electrode. In addition, by changing the ITO force of the transparent electrode to the copper fine wire + ITO as in Example 2-3, the heat dissipation of the transparent electrode force can be improved, and the luminance half-life is further increased. When the average particle diameter of the phosphor particles was reduced as in Example 24, the amount of heat generation was increased, and as a result, the heat dissipation effect was enhanced and the life was improved compared to Example 2-1. Furthermore, the best results were obtained by changing the transparent electrode to copper fine wire + ITO as in Example 2-5.

 [0113] Although the present invention has been described in detail and with reference to specific embodiments, it will be apparent to those skilled in the art that various changes and modifications can be made without departing from the spirit and scope of the invention. is there.

 This application is based on a Japanese patent application filed on July 15, 2004 (Japanese Patent Application No. 2004-208790) and a Japanese patent application filed on July 28, 2004 (Japanese Patent Application No. 2004-220330). Incorporated herein by reference.

Claims

The scope of the claims

 [1] An inorganic dispersion-type electroluminescent device having at least a light emitting layer between a pair of electrodes such as a back electrode and a transparent electrode, on the surface opposite to the light emitting layer of the back electrode

An inorganic dispersive electoluminescence element comprising a ceramic sheet having a thermal emissivity of 0.8 or more and a thickness of 50 μm to 1000 μm.

[2] An inorganic dispersion-type electoluminescent element having at least a light emitting layer between a pair of electrodes such as a back electrode and a transparent electrode, wherein the back electrode is a graphite sheet Dispersion type electoluminescence element.

[3] The inorganic dispersive electoluminescence device according to [1], wherein the back electrode is a graphite sheet.

 [4] The inorganic dispersive electoluminescence device according to [2] or [3], wherein the back electrode has a thermal conductivity of 200 WZm′K or more.

[5] The transparent electrode according to any one of claims 1 to 4, wherein the transparent electrode is a transparent conductive sheet having a transparent conductive film portion and a fine wire structure portion of metal and Z or alloy. Inorganic dispersion type electoluminescence element.

[6] The inorganic dispersed electoluminescence device according to any one of [1] to [5], wherein an average size of the phosphor particles contained in the light emitting layer is 0.1 to 15 m.