JPH0757874A - Element for dispersion type el panel - Google Patents

Abstract

PURPOSE:To attain a low voltage drive with a super-high illuminance, and improve moisture resistance by laminating a transparent conductive film and a light emitting layer, and forming the light emitting layer by dispersing phosphor particles covered with dielectric films in a dispersing medium. CONSTITUTION:An element for dispersed type EL panel A is formed of a transparent conductive layer 2, a light emitting layer 3, and a back plate 7, which are successively laminated, and in the light emitting layer 3, phosphor particles 4 covered with dielectric films 5 are dispersed in a dispersing medium 6. The particles 4 covered with the dielectric films 5 are made into paste with a dimethyl formamido solution of cyano ethylpuran followed by printing, and dried. Then, the light emitting layer 3 in which the particles 4 covered with the dielectrics 5 are dispersed with the cyano ethylpuran as the dispersing medium 6 can be provided. Since the particles 4 are covered with the films 5, penetration of moisture is prevented, and the moisture contained in the dispersing medium 6 is removed with the film 5 as a barrier layer.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a dispersion type EL panel element, and more particularly, to an element having an ultrahigh brightness, a low voltage drive and improved moisture resistance, which enables an ultrathin shape. .

[0002]

2. Description of the Related Art Conventionally, an element 11 for a dispersion type EL panel
As shown in FIG. 2, the transparent conductive film 12,
ZnS: Cu, Al, ZnS: Cu, Cl, or other fluorescent material dispersed light emitting layer 13, dielectric material dispersed dielectric layer 2
It is known that a back electrode 17 made of 0, Al foil or the like is laminated. In order to further improve the moisture resistance, a hygroscopic nylon 6 film 18 is laminated on the back electrode 17, and the entire element is made of polychlorotriline. A structure in which a fluoroethylene film is hermetically sealed is known. In such an element 11 for dispersion type EL panel, high brightness and high reliability are obtained by laminating a dielectric material on the phosphor.

[0003]

However, in such a conventional dispersion type E panel element 11, the light emitting layer 13 is used.
, The phosphor is pasted with a dimethylformamide solution of cyanoethylplan and printed, and the film thickness is limited by the printing plate. This film thickness is usually 40 to 60 μm.
It has been considered difficult to reduce the thickness to about 30 μm or less in about m. Further, a dielectric layer is printed between the light emitting layer and the Al foil, and the thickness is 4 μm when the particle size of the dielectric layer is 1 to 3 μm.
It is about 0 to 50 μm. Therefore, the total thickness of the light emitting layer and the dielectric layer is about 100 μm,
Normally, a voltage is applied to both ends so that an electric field of about 10 ⁵ to 10 ⁶ V / cm is applied, so that the applied voltage becomes as large as about 120V. Further, the surface emitting phosphor contributes to the brightness, but the emitting light emitting layer on the dielectric layer side does not contribute to the brightness, and further improvement in brightness is desired. Further, in the conventional element for dispersion type EL panel, the main cause of the deterioration is due to moisture, but the fluorescent substance and the dielectric layer are formed separately, and each of them is formed of cyanoethyl as the fluorescent substance or the dielectric substance. It is printed as a paste with a solution of pullulan in dimethylformamide. In this case, it is difficult to remove water from the cyanoethyl pullulan dissolved in dimethylformamide, which is an organic solvent having a large polarity, which is used when forming a paste, and it is difficult to remove the water due to the vapor pressure of each, and the moisture content in the panel is There is a limit to removal, and it has been desired to deal with deterioration due to moisture. Under the circumstances, the present invention is based on the conventional distributed E
It is intended to solve the problems of luminance, driving voltage, and moisture resistance in an L panel element, and a structure in which a dispersion type EL panel element has ultrahigh brightness, can be driven at a low voltage, and has improved moisture resistance. It is intended to provide a panel of.

[0004]

As shown in FIGS. 1A and 1B, a dispersion type EL panel element of the present invention comprises a transparent conductive film 2, a light emitting layer 3 and a back electrode 7, which are laminated. Becomes
The light emitting layer 3 includes fluorescent particles 4 covered with a dielectric coating 5.
Are dispersed in the dispersion medium 6. The dielectric film 5 is made of TiO ₂ , Y ₂ O ₃ , Nb.
Any dielectric selected from ₂ O ₅ , SnO ₂ , BaTiO ₃ , and HfO ₂ can be used, and in particular, in order to obtain the most effect as a moisture barrier layer for improving the moisture resistance, which will be described later, , BaTiO ₃ , TiO ₂ , HfO
It is preferably ₂ . Furthermore, the dispersion medium 6 that disperses the fluorescent particles 4 covered with the dielectric coating 5 can be cyanoethyl pullulan. In the element for dispersion type EL panel of the present invention, the phosphor particles 4 include ZnS and C
u, added with Al (ZnS: Cu, Al), Zn
Cu and Cl added to S (ZnS: Cu, Cl)
Etc. can be used. The fluorescent particles 4 covered with the dielectric coating 5 are made into a paste with a solution of cyanoethyl pullulan in dimethylformamide, printed, and dried to use cyanoethyl pullulan as a dispersion medium 6 for dielectric. A light-emitting layer 3 in which the phosphor particles 4 coated with the body 5 are dispersed is obtained. In the conventional element for dispersion type EL panel, it is necessary to form two layers of a light emitting layer and a dielectric layer between the transparent conductive film and the back electrode,
The total thickness of the light emitting layer and the dielectric layer was about 100 μm. However, in the dispersion type EL panel element of the present invention,
Only the light emitting layer 3 in which the phosphor particles 4 coated with the dielectric 5 are dispersed is formed, and the thickness of the light emitting layer 3 is 50 μm.
Since it is about m, it is significantly thinned as compared with the conventional one. A hygroscopic film 8 such as a nylon 6 film is arranged on the outer side of the back electrode 7, and a transparent conductive film 2 is provided.
It is possible to cover the outer side of the above and the outer side of the hygroscopic film 8 with the moistureproof films 9a and 9b made of polychlorofluoroethylene or the like.

As shown in FIG. 5, the above-mentioned luminescent layer 3 is prepared by suspending the phosphor in ethyl alcohol and atomizing it with nitrogen gas, and spraying the dielectric sol with nitrogen gas. The shaped thing is put in one chamber, heated and dried to prepare a state in which the primary particles 3 of the fluorescent substance are covered with a dielectric film, and this is collected by a cyclone. Then, the fluorescent particles 4 covered with the collected dielectric film 5 are printed in a paste form with a dimethylformamide solution of cyanoethyl pullulan or the like, and the paste is printed to dry the cyanoethyl pullulan dispersion medium 6. As dielectric 5
Emitting layer 3 in which phosphor particles 4 coated with
To make. Also in the EL panel element of the present invention, a voltage may be applied to both ends of the light emitting layer so that an electric field of about 10 ⁵ to 10 ⁶ V / cm may be applied, as in the conventional case. Since the sum of the thickness of the light emitting layer and the dielectric layer is about half, in order to obtain the same electric field as before, the applied voltage for light emission applied to both ends of the light emitting layer should be about half of the conventional voltage. Good.

In the EL panel element of the present invention, since the particles 4 of the fluorescent substance are coated with the dielectric coating 5, the structure prevents the infiltration of water. In a conventional dispersion-type EL panel element, a dimethylformamide solution of cyanoethyl pullulan comes into direct contact with a phosphor when a light emitting layer is formed. In particular, cyanoethyl pullulan as a dispersion medium has a functional group in its synthesis. Since it contains water corresponding to the substitution ratio of and it is difficult to completely remove it, deterioration due to water is unavoidable. However, in the dispersion type EL panel element of the present invention, The film 5 serves as a barrier layer to improve moisture resistance.

The brightness of the device also varies depending on the amount of the dielectric coating 5 deposited around the phosphor particles 4, but TiO ₂ is used as the dielectric coating to perform spraying and drying operations for coating formation. The luminance-voltage characteristics when repeated three times are as shown in FIG. Compared with the conventional element for dispersion type EL panel, the luminance at the same applied voltage is several times higher in the present invention.
It is improved several tens of times, and it is possible to drive at a lower voltage than conventional ones. This is because in the case of the present invention, the electric field of the light emitting layer is the same as that of the conventional one, and only about half the voltage is required, and in the past, even if the fluorescent substance emits light, it does not appear on the surface. In the case of the present invention, on the contrary, in the case of the present invention, since the transparent dielectric film is arranged around the fluorescent body, the light of the fluorescent body emitting light at the lower side does not It is judged that it contributes to the brightness by passing through and coming out. The amount of the coating seems to be almost proportional to the number of times the phosphor particles pass through the heating / drying chamber shown in FIG. 5, but the relative brightness was as shown in FIG. 6 depending on the number of passes. As the film becomes thicker, the relative brightness also rises, and after 3 to 4 times, M
When the thickness becomes ax and becomes thicker than that, the relative luminance tends to decrease, and it is necessary to select an appropriate film thickness from the relative luminance. The reason for this is that when the light emitting layer 3 is prepared by pasting, if the dielectric film 5 becomes too thick, the distance between the phosphor particles 4 becomes too wide, and the number of the phosphor particles 4 itself decreases. It is decided that it depends.

[0008]

In the EL panel element of the present invention, the light emitting layer has a structure in which the fluorescent particles covered with the dielectric coating are dispersed in the dispersion medium. There is no need to form a dielectric layer, a transparent conductive film, a light emitting layer,
The configuration including the back electrode is made possible, and as a result, the thickness of the light emitting layer between the transparent conductive film and the back electrode can be reduced, and low voltage driving and high brightness display are possible. Also, by forming a dielectric coating on the phosphor, it is possible to efficiently contribute to the emission of light from the phosphor. Furthermore, since the dielectric film functions as a moisture barrier layer, deterioration due to moisture contained in the dispersion medium can be prevented, and a dispersion-type EL panel element having high humidity resistance can be obtained.

[0009]

Embodiments of the present invention will be described with reference to the drawings.
FIG. 5 is a diagram showing a manufacturing process of a fluorescent substance with a dielectric coating used for the dispersion type EL panel element of the present invention, and FIG. 7 is a view showing a manufacturing process of the dispersion type EL panel element of the present invention. First, a dielectric sol having an average particle size of 10 nm and a TiO ₂ content of 4 to 7%, and a particle size of 15 to 40 μm (average particle size of 30 μm).
m) the phosphors ZnS: Cu, Al suspended in ethanol were each used as a carrier gas using a quartz glass atomizer and N ₂ gas having a flow rate of 0.3 to 1.0 Kg / cm ² as a carrier gas. 300-600 ° c from spray nozzle
Sent to the heating and drying chamber 24 set to
A TiO ₂ coating was formed on the surface of the phosphor. The fluorescent material on which the dielectric film was formed, which passed through the chamber, was collected through the cyclone 25. Next, the collected fluorescent substance with the TiO ₂ coating is again sprayed into the chamber 24 together with the above-mentioned dielectric sol and fed to form a TiO ₂ coating, and the cyclone 25 collects after passing through the chamber. This was repeated once to obtain a phosphor having a TiO ₂ film having a predetermined film thickness (spray drying treatment). Ti obtained
65 parts of the O ₂ -coated phosphor and 35 parts of a dimethylformamide solution of cyanoethylplan (concentration: 60% by weight) were mixed and stirred with a homogenizer at 3000 rpm for about 1 hour to form a paste. The mixing ratio of the fluorescent substance and the dimethylformamide solution of cyanoethyl pullulan is such that the fluorescent substances 60 to 75 are adjusted so that the dielectric constant of the entire EL panel element becomes high.
It is preferable to use 25 to 40 parts of a solution of cyanoethylplan in dimethylformamide for each part (paste). Then, this was printed on a 100 μm thick Al foil, which is a back electrode, using a printing plate (printing). Then
This was dried at 175 ° C. for 60 minutes in a N ₂ gas atmosphere. In parallel with this, a transparent conductive film (70 μm
A silver collector electrode was printed on the sheet with a thickness of 100Ω / □). This is an electrode required for uniform surface emission. A carbon electrode may be used to reduce the cost. The silver particle diameter of the collector electrode was 2 to 7 μm, and fine powder was printed, followed by drying at 110 ° C. for 30 minutes. Then, the lead terminals are fixed to the printed Al foil and the conductive film with heat-resistant fixing tape, and the polychlorotrifluoroethylene moisture-proof film, nylon 6 film, A
1 foil, a transparent conductive film, and a polychlorotrifluoroethylene moisture-proof film were laminated in this order and quickly laminated (lamination). Next, the extra film portion was punched (press molding) with a simple press to fabricate an EL panel element. Before laminating, the nylon 6 film and the polychlorotrifluoroethylene moisture-proof film are dried at 100 to 120 ° C. for 2 to 5 hours to remove water.

[0010]

According to the present invention, a dispersion type EL panel element capable of low voltage driving and high luminance display can be obtained. Further, it is possible to improve the humidity resistance and obtain an element for dispersion type EL panel in which the deterioration of the brightness due to moisture is extremely small. .

[Brief description of drawings]

FIG. 1 is a diagram showing a cross section of an element for a dispersion-type EL panel of the present invention.

FIG. 2 is a view showing a cross section of a conventional element for a dispersion type EL panel.

FIG. 3 is a diagram showing luminance-voltage characteristics of the element for dispersed EL panel of the present invention.

FIG. 4 is a diagram showing the results of accelerated life test of the element for dispersed EL panel of the present invention.

FIG. 5 is a diagram showing a process of spray-drying a phosphor used in the element for a dispersion-type EL panel of the present invention.

FIG. 6 is the number of spray drying treatments of the phosphor and the dispersion type E of the present invention.
The figure which shows the brightness | luminance relationship of the element for L panels.

FIG. 7 is a diagram showing a manufacturing process of an element for dispersed EL panel of an example.

[Explanation of symbols]

1 Dispersion type EL panel element of the present invention 2, 12 Transparent conductive film 3, 13 Light emitting layer 4 Fluorescent body 5 Dielectric coating 6 Dispersion medium 7, 17 Back electrode 8, 18 Nylon 6 film 9a, 9b Polychlorotrifluoro Ethylene film 19a, 19b Polychlorotrifluoroethylene film 11 Conventional dispersion type EL panel element 20 Dielectric layer 24 Heating / drying chamber 25 Cyclone

Claims (3)

[Claims] 1. An element used in an EL panel, comprising a transparent conductive film, a light emitting layer, and a back electrode laminated, wherein the light emitting layer comprises fluorescent particles covered with a dielectric film as a dispersion medium. An element for a dispersion-type EL panel, characterized in that it is dispersed in. 2. The dielectric coating is TiO ₂ , Y ₂ O ₃ , Nb ₂
The element for a dispersion-type EL panel according to claim 1, comprising a dielectric material selected from O ₅ , SnO ₂ , BaTiO ₃ , and HfO ₂ . 3. The element for a dispersion type EL panel according to claim 1, wherein the dispersion medium for dispersing the fluorescent substance particles covered with the dielectric film is cyanoethyl pullulan.