JP2006066133A - Surface-emitting device and illuminated display device using it - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To drastically facilitate discrimination of characters and symbols even in the dark such as discrimination characters and symbols equivalent to an ID of an object such as the number of a vehicle, and enable to easily mount a device for such discrimination without the need of any special processing on an installation site. <P>SOLUTION: The illumination device has an electroluminescent element, an optical member imparting directivity to emission light from the electroluminescent element, a transmission sheet on which discrimination characters or symbols equivalent to the ID of an object are printed, or a surface-emitting sheet equipped with cut-out discrimination characters and symbols incorporated for display. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a directional surface illumination device using an electroluminescence element. In particular, the present invention relates to an illumination display device for an identification character or an identification symbol corresponding to an object ID.

  An electroluminescence (hereinafter also referred to as “EL”) element is a surface-emitting light source, and a dispersion-type EL element is known in which a phosphor powder is sandwiched between electrodes to form a light-emitting element. The general shape of a dispersion-type EL element consists of a structure in which phosphor powder is dispersed in a binder with a high dielectric constant, and at least one is sandwiched between two transparent electrodes. Light is emitted by applying an electric field. A light emitting device made of phosphor powder can be made to have a thickness of several millimeters or less, is a surface light emitter, has many advantages such as low heat generation and excellent light resistance and heat resistance. There are applications as lighting for various interiors and exteriors, light sources for flat panel displays such as liquid crystal displays, and illumination light sources for large areas.

  Dispersive EL elements do not use a high-temperature process, so that it is possible to form flexible elements using plastic as a substrate, and they can be manufactured at a low cost in a relatively simple process without using a vacuum apparatus. In addition, it has the feature that the emission color of the element can be easily adjusted by mixing a plurality of phosphor particles having different emission colors, and is applied to backlights and display elements such as LCDs. Furthermore, it has been strongly desired to apply such a characteristic to a light-emitting body that displays characters and symbols.

However, the dispersion type EL element has a defect that the outline of a display object or characters is blurred by emitting light in multiple directions. Therefore, as a means for solving this, a sheet made of a lens such as a prism is EL. Combination with an element sheet is described in Patent Document 1 and Patent Document 2.
JP-A-9-73983 JP 2003-197364 A

  However, a means for achieving a sufficiently high luminance and long life has not yet been obtained, and it has been insufficient to express information such as characters and symbols in a high luminance state without bleeding. Dispersive EL elements can generally adjust the luminance by voltage. However, increasing the luminance makes the lifetime extremely short, so it has a high luminance and a long lifetime, and reduces blurring and blurring of characters and symbols under high luminance. However, with the technique described in the above-mentioned patent document, the solution of such a problem is still insufficient.

Accordingly, an object of the present invention is to provide an EL element sheet having high recognizability and high brightness and long life that could not be realized conventionally.
Another object of the present invention is to provide a distributed EL element having directivity suitable for displaying an identification character or an identification symbol corresponding to an object ID. Another object of the present invention is to provide a lighting device with high added value incorporating a dispersion type EL element having directivity.

The above object of the present invention can be achieved by the following constitution.
(1) A surface light emitting device comprising an inorganic dispersive electroluminescent element having a luminous efficiency of 15 lumen / W or more at a light emission luminance of 100 cd / m ² and a directional optical member.
(2) A surface light emitting device comprising an inorganic dispersive electroluminescent element having a luminous efficiency of 15 lumen / W or more at a light emission luminance of 200 cd / m ² and a directional optical member.

(3) An illumination display device characterized in that characters, figures, symbols, or image information that is a combination thereof is provided on the light emitting side of the surface light emitting device according to (1) or (2).
(4) The illumination display device according to (3), wherein the image information is an identification character or an identification symbol corresponding to the ID of the object.
(5) The illumination display device according to (4), wherein the image information is an automobile number.

  According to the present invention, by using an inorganic dispersion-type EL element having a specific luminous efficiency in combination with a directional optical member, a surface light emitting device having a high luminance and a long life and good visibility can be obtained, and this can be used as a light source. Thus, it can be easily mounted on an existing product that is difficult to process and attach, such as a license plate, and can be used as an excellent illumination display device for a long time. Furthermore, it is a device that can give high added value to differentiation from others, and can compensate for the weaknesses of EL, which is an expensive material.

  The present invention is a distributed EL element (surface emitting device) suitable for a lighting device having directivity, and an illumination display device incorporating the distributed EL element.

The dispersion type EL element of the present invention has a configuration in which a light emitting layer is sandwiched between a pair of opposing electrodes, at least one of which is transparent. It is preferable that a dielectric layer is adjacent between the light emitting layer and the electrode. The EL element of the present invention is characterized in that the luminous efficiency is 15 lumen / W or more at an emission luminance of 100 cd / m ² . By using an EL element having such luminous efficiency in combination with a directional member, a surface light emitting device having high luminance, long life, good visibility, and excellent practicality can be obtained. From the viewpoint of high luminance and long life, the luminous efficiency of the EL element is more preferably 15 lumen / W or more at an emission luminance of 200 cd / m ² . The light emission luminance of the present invention can be measured using a luminance meter, and specifically, can be measured by focusing on the measurement surface with a BM9 manufactured by Topcon Corporation.

The EL device having high luminous efficiency of the present invention can be achieved by appropriately using the following techniques (1) to (5), preferably by combining two or more.
(1) EL phosphor particles having high luminous efficiency (for example, particles having a particle size in the range of 0.1 μm to 15 μm, particles having a coefficient of variation of less than 35%, particles having a high stacking fault density, etc.) use. (2) Use low resistance transparent electrodes. (3) The thickness of the light emitting layer is 0.5-30 μm. (4) The phosphor content in the light emitting layer is 40 to 95% by mass. (5) The dielectric particle content of the dielectric layer is 40 to 95% by mass.
In particular, it is preferable to use the above technique (1) in combination with at least one of the above techniques (2) to (5). The EL element with high luminous efficiency of the present invention suppresses heat generation of the driving EL element even when driven at high luminance, and achieves both visibility and life by using in combination with a directional member. Can do.

  For example, as shown in FIG. 1, the dispersion type EL element of the present invention has a configuration in which a light emitting layer 1 is sandwiched between opposing transparent electrodes 2 and 3. Furthermore, it is preferable to have the dielectric layer 4 between the light emitting layer 1 and the electrode 3, to have the film base 5 on the transparent electrode 2, and to seal with moisture-proof films 6a and 6b.

As the base material of the phosphor particles preferably used for the light emitting layer of the present invention, specifically, one or more elements selected from the group consisting of Group II elements and Group VI elements, and Group III elements And a semiconductor fine particle composed of one or a plurality of elements selected from the group consisting of Group V elements, and is arbitrarily selected depending on the necessary emission wavelength region. Examples thereof include CdS, CdSe, CdTe, ZnS, ZnSe, ZnTe, CaS, MgS, SrS, GaP, GaAs, and mixed crystals thereof, CaGa ₂ S ₄ , SrGa ₂ S ₄ , BaAl ₂ S _{4, and the} like. ZnS, CaS, SrS, etc. can be preferably used. As the activator, metal ions such as Mn and Cu and rare earth elements can be preferably used. As the coactivator, in addition to halogen elements such as Cl, Br, and I, Al or the like can be preferably used. Furthermore, it is also preferable to add elements such as Au, Sb and Bi in order to extend the lifetime of the phosphor particles.

  As the phosphor fine particles usable in the present invention, a firing method (solid phase method) in which a phosphor base material, an activator and a flux are mixed and fired can be preferably used. As the flux, it is preferable to use halides of alkali metals and alkaline earth metals, and the addition amount of the flux is preferably 20% by mass or more with respect to the phosphor raw material, and 40% by mass or more is finely dispersed and monodispersed. It is particularly preferable for obtaining phosphor particles. Furthermore, it is also preferable to add a particle growth inhibitor and bake to obtain fine phosphor particles. Also formed by hydrothermal synthesis method that synthesizes in a heated and pressurized solvent, urea melting method that uses molten urea as a reaction solvent, spray pyrolysis method that thermally decomposes the liquid for phosphor precursor that has been made into fine droplets, etc. It is also more preferable to obtain monodispersed phosphor particles with fine particles. In forming phosphor particles, it is preferable to provide a step of applying a physical impact to the formation process in order to increase the luminance of the EL element. Further, the phosphor particles preferably have a non-light emitting shell layer of oxide or nitride in the range of 0.01 μm or more and 1.0 μm or less on the particle surface in order to prevent deterioration due to moisture.

  The particle size of the EL phosphor particles of the present invention is preferably in the range of 0.1 μm to 15 μm. This is because EL phosphor particles greatly contribute to light emission near the particle surface of the EL phosphor, and reducing the particle size to increase the specific surface area leads to improvement in luminous efficiency. Further, when the variation coefficient of the particle size is widened, a large amount of coarse particles and fine particles having low light emission efficiency are contained. Therefore, the variation coefficient is preferably less than 35%. Furthermore, the EL phosphor particles are excited and emit light by the electrons generated from the copper compound segregated in the crystal by the application of an electric field. However, in the case of a ZnS phosphor, this copper compound is formed in a stacking fault. Therefore, it is preferable that the stacking fault density of the particles is high. It is preferable to have 30% or more of particles containing 10 or more stacking faults with a spacing of 5 nm or less.

As the light emitting layer, a material in which phosphor particles are dispersed in a dispersant can be used. As the dispersant, a polymer having a relatively high dielectric constant, such as a cyanoethyl cellulose resin, or a resin such as polyethylene, polypropylene, polystyrene resin, silicone resin, epoxy resin, or vinylidene fluoride can be used. The dielectric constant can be adjusted by appropriately mixing fine particles having a high dielectric constant such as BaTiO ₃ and SrTiO _{3 with} these resins. As a dispersion method, a homogenizer, a planetary kneader, a roll kneader, an ultrasonic disperser, or the like can be used.

  The transparent electrode used for at least one of the pair of electrodes of the EL element is a combination of ITO formed by sputtering or the like, a thin film in which conductive fine particles are dispersed and applied in a binder, and a mesh-like metal electrode, etc. Etc. are preferably used. The surface resistance value of the transparent electrode is preferably in the range of 0.01Ω / □ to 100Ω / □, particularly preferably in the range of 30Ω / □.

As the dielectric layer, any material can be used as long as it has a high dielectric constant and insulation and has a high dielectric breakdown voltage. These are selected from metal oxides and nitrides, such as TiO ₂ , BaTiO ₃ , SrTiO ₃ , PbTiO ₃ , KNbO ₃ , PbNbO ₃ , Ta ₂ O ₃ , BaTa ₂ O ₆ , LiTaO ₃ , Y ₂ O ₃ , Al. ₂ O ₃ , ZrO ₂ , AlON, ZnS or the like is used. These may be installed as a uniform film, or may be used as a film having a particle structure. In the case of a uniform film, the method for preparing the dielectric film may be a vacuum film forming method such as sputtering or vacuum deposition. In this case, the thickness of the film is usually in the range of 0.1 μm to 10 μm.

  The light emitting layer and the dielectric layer are preferably applied 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 capable of continuous application such as a doctor blade method, a slide coating method, and an extrusion coating method.

  In the present invention, the thickness of the light emitting layer (film thickness after drying of the coating film) is preferably in the range of 0.5 μm or more and 30 μm or less in order to increase the electric field strength applied to the EL element and obtain high luminance, The total film thickness of the sandwiched light emitting layer and dielectric layer is preferably in the range of 1 μm to 50 μm. The phosphor content in the light emitting layer is preferably in the range of 40% by mass to 95% by mass in order to increase the particle density and obtain high brightness. The dielectric particle content of the dielectric layer is preferably in the range of 40% by mass to 95% by mass in order to increase the dielectric constant of the dielectric layer and concentrate the electric field on the light emitting layer.

The EL element of the present invention is preferably sealed with a moisture-proof film having a water vapor transmission rate of 0.05 g / m ² / day or less in order to prevent deterioration due to moisture. In addition, in order to cancel or absorb vibration and noise due to driving of the EL element, a compensation electrode layer is provided with an insulating layer interposed therebetween, and a voltage having a phase opposite to that applied to the light emitting layer is applied, or a buffer material layer Is preferably imparted to the EL element.

  Considering the application of the present invention, the emission color is preferably white. Examples of a method for making the emission color white include a method using phosphor particles that emit white light alone, such as a zinc sulfide phosphor activated by manganese with copper and gradually cooled after firing, or three primary colors or A method of mixing a plurality of phosphors that emit light in complementary colors is preferable. (A combination of blue-green-red, a combination of blue-green-orange, etc.) Also, like the blue color described in JP-A-7-166161, JP-A-9-245511, and JP-A-2002-62530 Also preferred is a method in which light is emitted at a short wavelength, and a part of the light emission is converted into green or red by using a fluorescent pigment or a fluorescent dye (light emission) and whitened. Further, the CIE chromaticity coordinates (x, y) preferably have an x value in the range of 0.30 to 0.43 and a y value in the range of 0.27 to 0.41.

  The directional sheet in the present invention is preferably a transparent resin such as an acrylic resin, a polycarbonate resin, or a polyethylene resin, and is not limited to colorless and transparent, and may be a resin added with a colorant. The thickness of the directional sheet is not limited, but is preferably 30 μm or more, more preferably 50 μm or more.

  In the directional sheet, a light emitting surface of an EL sheet is bonded to a prism lens sheet which is an example of a lens sheet, and light is emitted through the prism lens sheet. The prism lens sheet preferably has a plurality of triangular prisms or lens-like spherical bodies as lens bodies formed on the surface thereof. As shown in detail in the surface light emitting element (a) of FIG. 3, the prism body is formed in the same cross-sectional shape (directional sheet 12a), and in the same direction (perpendicular to the plane of the drawing) along the sheet plane. It extends straight and directs the light emitted from the EL sheet 10 in a predetermined direction. The lens-shaped spherical body is also formed in the same cross-sectional shape as shown in detail in the surface light emitting element (b) of FIG. 3 (directional sheet 12b), and in the same direction along the sheet plane (perpendicular to the paper surface). The light emitted from the EL sheet 10 is directed in a predetermined direction. More specifically, the three-dimensional pattern having a lens function is a three-dimensional pattern in which the prisms are substantially triangular and arranged so that the directions of the ridges are substantially parallel to each other, or a columnar body with a sinusoidal cross section. Solid patterns arranged so that the length directions are almost parallel to each other, or solid shapes arranged so that the length directions are almost parallel to each other with columnar bodies having a semicircular cross-section, or pyramidal or hemispherical projections It is a three-dimensional pattern with a unit of shape.

  The prism-shaped triangular prism has a triangular cross section, and the shape of the triangle may be either equilateral or unequal, but when guiding outgoing light in a direction perpendicular to the EL light emitting layer surface, an equilateral triangle, particularly an isosceles triangle, is used. It is preferable to integrate in the emission direction. The apex angle of the triangle can be selected widely, but is preferably 60 to 150 °. Within this range, the emission direction is not excessively divided and an effect of directing in the desired emission direction is obtained, which is preferable. In addition, a lens array in which the directions of the top ridges are substantially parallel and at the same time the slopes of the triangular prisms are connected so that the intersection lines of the slopes of the adjacent triangular prisms are in common is preferable. Further, this prism shape may be a lens array having a curvature at the top and / or valley, and is a sinusoidal corrugated columnar body having a curvature at both the top and the valley. A three-dimensional pattern arranged in parallel may be used. Furthermore, it is also possible to use a three-dimensional pattern in which the cross-section is semicircular or a circular arc columnar part of a part of a circle and arranged so that the length directions thereof are substantially parallel to each other. A lens array in which pyramidal or hemispherical convex units are continuously arranged on a plane is also preferable.

Next, an illumination display device using the surface light emitting device of the present invention will be described.
The present invention is characterized in that image information that is a character, a figure, a symbol, or a combination thereof is provided on the light emitting side of the surface light emitting device.

  As a method of providing the image information on the light emitting side of the surface light emitting device, the image information is printed or printed on a transmissive sheet, and the transmissive sheet is incorporated on the light emitting side of the surface light emitting device. A method of attaching directly to the light emitting side of the surface light emitting device in a cutout form that does not transmit light, or a method of attaching to the outside of the directional sheet, or a direct surface emission in a cutout form that substantially transmits light. For example, a method of adhering to the light emitting side of the apparatus or the outside of the directional sheet is exemplified.

As a method of printing or printing image information on a transparent sheet, printing may be performed by using ink such as inkjet on a transparent plastic sheet such as PET / TAC coated with a binder layer that easily adheres ink such as gelatin. The oil-based ink may be printed directly on the plastic sheet by offset printing or screen printing. Further, a silver salt type transmission sheet with high productivity may be used in consideration of small-quantity production. The material to be printed is preferably excellent in heat resistance and light resistance. Further, the permeable sheet is preferably made of a material having a high tensile strength in order to prevent pressure bonding by a laminator or the like, and specifically, has a tensile strength of 8 kgf / mm ² or more. Furthermore, the thickness of the transparent sheet is preferably 50 μm or more, more preferably 100 μm or more, still more preferably 150 μm or more, and 500 μm or less.

  The density of the image information is not particularly limited, but it is preferable that the density difference between the background and the image information is larger. For example, it is preferable that the X-rite status A density has a density difference of 2.0 or more. The material is not particularly limited as long as it can be made substantially opaque, and a material that does not cause discoloration due to heat or light is preferable. A metal component that can be made into a thin layer at low cost, such as Al, Fe, and Cu, is preferable.

  The method of overlapping the transmission sheet having image information with the light emitting layer and the directional member is not particularly limited, and the order of the directional member on the light emitting layer and the transparent sheet having the image information thereon is most preferable. The order may be a transparent sheet having image information on the light emitting layer and a directional member thereon.

  Furthermore, a directional member on the light emitting layer, a transparent sheet having image information thereon, or a laminate in which cutout image information is arranged in order may be sealed with a laminator, and in that case, sealed at room temperature. A cold laminator is preferred.

  The image information of the present invention may consist of a plurality of arbitrary combinations of characters, figures, symbols, etc., and are displayed for commercial purposes, road signs and various guidance signs, identification characters corresponding to object IDs Or an identification symbol etc. are mentioned. In the present invention, from the viewpoint of clarifying the visibility of image information in a specific direction, the image information is preferably a road sign, a guide sign, or an identification character or an identification symbol corresponding to an object ID.

  Here, the “identification character or identification symbol corresponding to the object ID” is information indicating the attribution, affiliation or possession of the object to which the image information is attached or attached, and distinguishing it from other objects. Means a character or symbol to do. Specifically, there are a car number, a house nameplate, a residence display by letters, a symbol or mark indicating a place or presence used as a so-called landmark. Advertisements displayed using letters and symbols for commercial purposes reveal the name of the advertiser through some medium, such as an outdoor signage, and show and encourage ideas, products, and services without human intervention Therefore, it does not correspond to the identification character or identification symbol corresponding to the ID of the object referred to in the present invention.

  The “car number” in the present invention refers to a vehicle registration number unique to an automobile issued by the Ministry of Land, Infrastructure, Transport and Tourism Transport Bureau / Inspection Registration Office. In this case, the object corresponds to the car, and the identification character or symbol corresponding to the ID corresponds to the vehicle registration number. By cutting out letters representing numbers or laminating a transparent sheet on which letters are printed together with EL sheets, counterfeiting and alteration can be prevented and weight reduction can be realized.

  The “house nameplate” is a display indicating the householder of the house attached to the entrance or gate of the house. In this case, the object corresponds to the house, and the character corresponding to the ID corresponds to the first and last name written on the nameplate. The nameplate is preferably attached to or attached to existing equipment such as a built-in type, and the display sheet of the present application is one of suitable shapes.

  The illumination display device of the present invention is also preferably used as a light emitter that constitutes a display board that prompts guidance in a certain direction, such as a road sign or a display board, in addition to an identification symbol or an identification character corresponding to an ID.

  In the present invention, an AC 100V power source may be used as a power source, but a solar solar battery or a dry cell may be used as a power source, or in combination with an infrared sensor for the purpose of power saving, it emits light only when a person approaches. Also good.

  Specific examples of the EL display device of the present invention are described below, but the present invention is not limited to these examples.

Example 1
<Phosphor particles A>
To a dry powder obtained by adding 0.07 mol% of copper sulfate to ZnS to 25 g of zinc sulfide (ZnS) particle powder having a crystallite size of 25 nm, 1.0 g of sodium chloride as a flux, barium chloride dihydrate 2 0.1 g and 4.25 g of magnesium chloride hexahydrate were mixed to obtain a mixture. Next, the mixture was filled in an alumina crucible and fired at 1200 ° C. for 4 hours in air to obtain a fired product. Next, the fired product was washed with a 1N aqueous hydrochloric acid solution, and then washed with distilled water several times to remove the flux and obtain a powder. Next, the obtained powder was subjected to a ball mill treatment to such an extent that the powder was not pulverized, and then filled again into an alumina crucible and fired in air at 700 ° C. for 6 hours to obtain a powder. Next, the obtained powder was washed with a 10% KCN aqueous solution, and then washed with distilled water several times to remove excess copper compound deposited on the powder surface, whereby phosphor particles A were obtained.
The phosphor particles A thus obtained had an average particle size of 25 μm and a coefficient of variation of 43%. Further, the phosphor particles were pulverized with a mortar, and fragments having a thickness of 0.2 μm or less were taken out and observed with a transmission electron microscope having an acceleration voltage of 200 kV. As a result, 40% or more of the fragments had stacking faults of 5 nm or less. The part which has 10 sheets or more was included.

<Phosphor particles B>
To a dry powder obtained by adding 0.09 mol% of copper sulfate to ZnS to 25 g of zinc sulfide (ZnS) particle powder having a crystallite size of 25 nm, 2.0 g of sodium chloride as a flux, 27 strontium chloride hexahydrate 0.0 g and 8.5 g of magnesium chloride were mixed to obtain a mixture. Next, the mixture was filled in an alumina crucible and fired at 1200 ° C. for 4 hours in air to obtain a fired product. Next, the fired product was washed with a 1N aqueous hydrochloric acid solution, and then washed with distilled water several times to remove the flux and obtain a powder. Next, the obtained powder was subjected to a ball mill treatment to such an extent that the powder was not pulverized, and then filled again into an alumina crucible and fired in air at 700 ° C. for 6 hours to obtain a powder. Next, the obtained powder was washed with a 10% KCN aqueous solution, and then washed with distilled water several times to remove excess copper compound deposited on the powder surface, whereby phosphor particles B were obtained.
The phosphor particles B thus obtained had an average particle size of 14 μm and a coefficient of variation of 32%. Further, the phosphor particles were pulverized with a mortar, and fragments having a thickness of 0.2 μm or less were taken out and observed with a transmission electron microscope having an acceleration voltage of 200 kV. As a result, 80% or more of the fragments had stacking faults of 5 nm or less. The part which has 10 sheets or more was included.

<Phosphor particles C>
To a dry powder obtained by adding 0.09 mol% of copper sulfate to ZnS to 25 g of zinc sulfide (ZnS) particle powder having a crystallite size of 25 nm, 2.0 g of sodium chloride as a flux, 27 strontium chloride hexahydrate 0.0 g, 8.5 g of magnesium chloride, and 5 g of magnesium oxide as a particle growth inhibitor were mixed to obtain a mixture. Next, the mixture was filled in an alumina crucible and fired at 1200 ° C. for 4 hours in air to obtain a fired product. Next, the fired product was washed with a 1N aqueous hydrochloric acid solution, and then washed with distilled water several times to remove the flux and the particle growth inhibitor to obtain a powder. Next, the obtained powder was subjected to a ball mill treatment to such an extent that the powder was not pulverized, and then filled again into an alumina crucible and fired in air at 700 ° C. for 6 hours to obtain a powder. Next, the obtained powder was washed with a 10% KCN aqueous solution and then washed with distilled water several times to remove excess copper compound deposited on the powder surface, thereby obtaining phosphor particles C.
The phosphor particles C thus obtained had an average particle size of 9 μm and a coefficient of variation of 28%. Further, the phosphor particles were pulverized with a mortar, and fragments having a thickness of 0.2 μm or less were taken out and observed with a transmission electron microscope having an acceleration voltage of 200 kV. As a result, 80% or more of the fragments had stacking faults of 5 nm or less. The part which has 10 sheets or more was included.

<EL element A>
Using the phosphor particles A obtained above, a white EL element was prepared by the following method.
BaTiO ₃ dielectric fine particles (Cabot Specialties, Inc .; BT-02) with an average particle size of 0.2 μm are dispersed in a 30 wt% cyanoresin (Shin-Etsu Chemical Co., Ltd .; CR-S) solution, and the film thickness of the dielectric layer Was applied on a 75 μm thick aluminum sheet and dried at 120 ° C. for 1 hour. Subsequently, the phosphor particles A and the fluorescent pigment (manufactured by Sinloihi; FA-001) are in the range of x = 3.3 ± 0.2 and y = 3.4 ± 0.2 in CIE chromaticity coordinates. The mixture was dispersed in a 30 wt% cyanoresin solution, and a doctor blade was applied onto the dielectric layer so that the light emitting layer had a thickness of 50 μm, and dried at 120 ° C. for 1 hour to obtain a laminate.

  Next, a conductive film in which an ITO transparent electrode having a surface resistivity of 100 Ω / □ is vapor-deposited on a 75 μm-thick transparent PET film is laminated at 150 ° C. so that the ITO surface is in contact with the surface of the light emitting layer of the laminate. Thus, an EL cell was obtained. Next, after a terminal for power supply was pulled out from the ITO and aluminum sheet of this EL cell, an EL element A was obtained by laminating a nylon 6 film of a water absorption layer and a PCTFE film of a moisture-proof film.

<EL element B>
An EL element B was prepared in the same manner as the EL element A, except that the phosphor layer B was used and the thickness of the light emitting layer was 25 μm.

<EL element C>
An EL element C was produced in the same manner as the EL element A, except that the phosphor layer C was used and the thickness of the light emitting layer was 25 μm.

  After creating a transparent sheet X on which the identification character corresponding to the object ID is printed on the upper surface of the EL element A created as described above, the sheet is sandwiched from both sides with a laminate film Y as shown in FIG. did. An example of creating a house nameplate as an identification character corresponding to an object ID is shown below. Fuji Photo Film Co., Ltd., Fuji G Color Film Pro Laser FT uses a Durst Lanbda76 laser exposure machine to expose characters representing the first and last names displayed on the nameplate, and then a Noritz CSR development processor A transparent sheet X on which the identification characters were printed by printing was prepared. Lamination was performed using a roll laminator LOV6507 using an outdoor laminate film POL150 manufactured by KK Trading Co., Ltd. The light emitting element sheet thus obtained was designated as Sample 001.

  A light emitting element sheet was prepared on the EL element A shown in FIG. 2 by further bonding with two kinds of directional sheets made of acrylic resin shown in FIG. The directional sheet 12 (a) has a shape such that the cross section of the protrusion is an equilateral triangle with a side of 100 μm, and the directional sheet 12 (b) has a semicircle with a cross section of the protrusion of 50 μm on a side. Shape. Moreover, it was set as the form which has a parallel protrusion which maintains such a cross section. The size of the light emitting element sheet was 10 cm × 30 cm. Using EL elements B and C, light emitting element sheets were respectively prepared in the same manner as described above to obtain samples 004, 005, 006, and 007, 008, 009.

The EL device A created above in luminance of 50,100,200cd / m ^2, the EL elements B and C to drive in the luminance of 100,200cd / m ^2, its frequency fixed AC voltage to 120V Adjusted. At this time, the luminance was measured with a luminance meter (Topcon; BM9), and the power consumption when driving at each luminance was measured with a power multimeter (NF Circuit; 2721) to calculate the luminous efficiency. . The luminance half time τ300 when driving at an initial luminance of 300 cd / m ² was also measured. Furthermore, as an indicator of directivity from the front and oblique directions, the sensation of 10 people in five stages with respect to the spread of characters from the position 30 ° 120 cm away from the perpendicular and the front 120 cm in the irradiation direction in the direction in which the sample is irradiated Evaluation was performed in a dark room. For bleeding, the average value for both 30 ° and the front from the perpendicular was taken as 5 for a good state that clearly appeared and 1 for a bad state that appeared blurred. The results are shown in Table 1.

  It can be seen from Table 1 that the effects of the directivity sheets (a) and (b) are remarkably exhibited by combining with the B and C EL elements, and the bleeding performance is greatly improved.

Example 2
After the EL light emitting sheet was prepared in the same manner as in Example 1, an identification character corresponding to the ID of the object punched with an aluminum thin plate was created on the upper surface of the EL element A, and an opaque character Z colored green was created. As shown, the film was sandwiched between the laminate films Y and laminated to be bonded. An example of creating a car number as an identification character corresponding to an object ID is shown below.

  When the sheet-like illuminant shown in FIG. 4 was replaced with the illuminant of Example 1 except that the sheet-like illuminant was adjusted to the size of the license plate, the same effect was observed. The illumination display device of the present invention is thin and can be easily mounted without significant modification of the dedicated installation site of the car. Furthermore, the EL sheet shines brightly and clearly, so that the blocked character portion can be recognized clearly, indirect lighting from the periphery of the plate is unnecessary, and license plate identification during night driving is facilitated.

It is the schematic which shows the structural example of the EL element (light emitting element sheet | seat) which can be used for this invention. It is the schematic which shows the illumination display apparatus used in Example 1 of this invention. It is the schematic which shows the structural example of the surface emitting device of this invention. It is the schematic which shows the illumination display apparatus used in Example 2 of this invention.

Explanation of symbols

1 Light emitting layer 2 Transparent electrode (ITO layer)
3 Electrode 4 Dielectric layer 5 Film base 6a, 6b Moisture-proof film 10 EL light emitting sheet 12 (a), 12 (b) Directional sheet

Claims (5)

A surface light emitting device comprising: an inorganic dispersion type electroluminescent element having a luminous efficiency of 15 lumens / W or more at an emission luminance of 100 cd / m ² and a directional optical member. A surface light-emitting device comprising: an inorganic dispersion type electroluminescence element having a luminous efficiency of 15 lumen / W or more at an emission luminance of 200 cd / m ² and a directional optical member.   3. An illumination display device comprising: a light emitting side of a surface light emitting device according to claim 1 or 2; and image information that is a character, a figure, a symbol, or a combination thereof.   4. The illumination display device according to claim 3, wherein the image information is an identification character or an identification symbol corresponding to the ID of the object.   5. The illumination display device according to claim 4, wherein the image information is an automobile number.

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