JPH119U - EL element - Google Patents

Abstract

(57) [Problem] To provide an EL element having a small outer shape and a small thickness, and having the same function as a device provided with a moisture-proof film in light emission luminance and moisture-proof property. SOLUTION: A transparent electrode film 1 having a transparent electrode layer formed on an upper surface is formed, a light emitting layer 2 is formed on an upper surface of the transparent electrode film, an insulating layer 3 is formed on an upper surface of the light emitting layer, and an upper surface of the insulating layer is formed. Then, a back electrode layer 4 is sequentially formed. The light emitting layer 2 is composed of a cyanoethylated resin as a binder, and the insulating layer 3
The back electrode layer 4 is made of a fluororesin as a binder. Fluororesin layers 5a and 5b are formed on the outer surfaces of the transparent electrode film 1 and the back electrode layer 4.

Description

[Detailed description of the invention]

[0001]

[Industrial applications]

 The present invention relates to an EL device.

[0002]

[Prior art]

 As shown in FIG. 2, a general EL element conventionally used includes a light emitting layer 12, a light emitting layer 12, a transparent electrode film 11 formed by depositing a transparent electrode layer made of ITO on a polyethylene terephthalate (PET) film. An insulating layer 14 and a back electrode layer 16 are laminated thereon, and both sides of these laminated layers are sealed by sandwiching between moisture-proof films 20, 20.

The light emitting layer 12 is formed by dispersing a phosphor powder obtained by doping zinc sulfide (ZnS) with an activator such as Cu or Mn and an activator such as Cl in a cyanoethylated cyanoethylated highly inductive binder. It is composed of The insulating layer 14 is formed by dispersing a high dielectric substance such as barium titanate (BaTiO ₃ ) in a cyanoethylated cyanoethylated high dielectric binder. The back electrode layer 16 is made of carbon powder, silver powder, copper powder, or a mixture of these powders and polyester as a binder.

In the above-mentioned conventional technology, the thickness of each of the moisture-proof films 20, 20 is about 200 to 300 μm, occupying about half of the thickness of the entire EL element, and the outer shape is also around. Since each joining portion requires at least about 1 mm, the thickness and the outer shape are both large.

[0005] As described above, the EL element in the related art has a weak point that it cannot fully cope with a tendency to downsize a device to which the EL element is mounted. For this reason, attempts have been made to reduce the size of EL devices used in precision equipment such as watches and clocks.

FIG. 3 shows an example of an attempt to reduce the size of an EL element. The use of a fluororesin as a high dielectric binder for the light emitting layer 23 and the insulating layer 25 laminated on the upper surface of the transparent electrode layer 21 is shown. Increases moisture resistance. In addition, the outer shape of the moisture-proof film is reduced by eliminating the need for a joint around the moisture-proof films 30 provided on the outer surface of the transparent electrode layer 21 and the upper surface of the back electrode layer 26, and the durability is excellent. An EL element is intended (JP-A-57-63797).

[0007]

[Problems to be solved by the invention]

 In the prior art, sealing with a moisture-proof film improves the durability of the light-emitting layer, but is disadvantageous in terms of thickness and external dimensions. It is disadvantageous in terms of size, especially when it is incorporated into a small device such as a watch. On the other hand, the use of fluororesin as a binder for the high dielectric substance can cope with reducing the size of the outer shape, but it still requires moisture-proof films on both sides, so it is difficult to reduce the size. Not enough. In addition, fluororesin has a disadvantage that a sufficient light emission amount cannot be obtained because the dielectric constant is lower than that of a cyanoethylated cyanoethylated high dielectric binder.

Accordingly, an object of the present invention is to provide an EL device having a small outer shape and a small thickness, and having the same function as the device provided with a moisture-proof film in terms of luminous brightness and moisture-proof property.

[0009]

[Means for Solving the Problems]

 In order to solve the above problems, the EL device of the present invention employs the following means.

A transparent electrode film having a transparent electrode formed on the upper surface, a light emitting layer formed on the upper surface of the transparent electrode film, an insulating layer formed on the upper surface of the light emitting layer, and a light emitting layer formed on the upper surface of the insulating layer. In the EL device including the formed back electrode layer, the light emitting layer is formed using a cyanoethylated resin as a binder, and the insulating layer and the back electrode layer are formed using a fluorine resin as a binder.

[0011]

[Action]

 By forming the light-emitting layer using a cyanoethylated resin as a binder, an increase in luminance can be obtained, and by forming the insulating layer and the back electrode layer using a fluorine resin as a binder, an improvement in moisture resistance can be obtained. This makes it possible to reduce the thickness and size of the EL element by eliminating the need for a moisture-proof film, which occupies about half the thickness of the conventional EL element.

[0012]

【Example】

 Hereinafter, an embodiment of the present invention will be described with reference to FIG. The light emitting layer 2 is formed on the upper surface of the transparent electrode film 1, the insulating layer 3 is formed on the upper surface of the light emitting layer, and the back electrode layer 4 is formed on the upper surface.

The transparent electrode film 1 is formed by depositing ITO constituting a transparent electrode film on a polyethylene terephthalate (PET) film to form a transparent conductive film.

The light emitting layer 2 is formed by printing a light emitting ink on the upper surface of the transparent electrode film 1. Cu-doped zinc sulfide (ZnS) is used as a phosphor constituting the luminescent ink. 60 g of the phosphor and 10 g of cyanoethylated cellulose, which is a high dielectric substance, dissolved in 25 g of propylene carbonate as a binder in advance are used, and these are mixed to prepare a luminescent ink. The luminescent ink is attached to the upper surface of the transparent electrode film 1 by a method such as a screen printing method and the like, and the luminescent layer 2 is formed by heating and drying.

Next, an insulating layer 3 is formed on the upper surface of the light emitting layer 2 by the same method as the formation of the light emitting layer 2. The insulating layer 3 is formed by mixing and stirring 60 g of a high dielectric substance made of barium titanate (BaTiO ₃ ) with a binder obtained by previously dissolving 10 g of a copolymer of vinylidene fluoride and propylene hexafluoride in 25 g of methyl ethyl ketone. An insulating ink is prepared, the insulating ink is printed on the light emitting layer 2, and the insulating layer 3 containing the fluororesin binder is formed by heating and drying.

At this time, the fluorine-based binder has a lower dielectric constant than the cyanoethylated cellulose described in the related art, but has a very high dielectric constant of BaTiO ₃ (1800 (F / m)). The difference in the dielectric constant of the fluorine-based binder does not cause a significant difference in the luminance of the EL element.

Finally, a back electrode layer 4 is formed on the insulating layer 3. In this, the back electrode layer 4 is composed of carbon powder as a conductor and a fluororesin binder. Specifically, 30 g of carbon powder and 20 g of a copolymer of vinylidene fluoride and propylene hexafluoride in advance are used. Carbon ink was prepared by mixing with a binder dissolved in 50 g of methyl ethyl ketone, and the carbon ink was printed on the insulating layer 3 and then heated and dried.

As described above, by forming the transparent electrode film 1, the light emitting layer 2, the insulating layer 3, and the back electrode layer 4, the basic configuration of the EL device of this embodiment is completed. In this embodiment, in order to prevent moisture from invading into the light emitting layer, a configuration in which fluororesin layers 5a and 5b are provided on both outer surfaces of the EL element having the basic configuration is shown.

The fluororesin layers 5a and 5b are prepared by dissolving 10 g of a copolymer of vinylidene fluoride and propylene hexafluoride in 30 g of methyl ethyl ketone to produce a fluororesin ink, printing the ink on the surface to be formed by screen printing or the like, and heating the ink.・ It is formed by drying. The thickness of the fluororesin layer is about 10 μm.

The EL element thus obtained is not sealed with a moisture-proof film having a total thickness of about 500 μm between the upper and lower two pieces, and the insulating layer 3 and the back electrode layer 4 are made of a fluororesin as a binder. With this configuration, it is possible to prevent moisture from entering the light emitting layer 2. Therefore, if the device incorporating the EL element has a certain degree of hermeticity, the EL element sufficiently secures reliability. If a fluororesin layer 5a having a thickness of about 10 μm is formed on the outer surface of the transparent electrode film 1, the moisture-proof layer can be further enhanced.

Incidentally, the water absorption of the fluororesin is 0.04% or less, and there is a remarkable difference of 1/50 or less as compared with 2% of cyanoethylated cellulose. Satisfactorily functions as a protective layer against the penetration of water.

[0022]

[Effect of the invention]

 According to the present invention, the light-emitting layer is formed using a cyanoethylated resin as a binder, and the insulating layer and the back electrode layer are formed using a fluorine resin as a binder. It is possible to provide an EL device which is excellent in shape and excellent in moisture resistance.

[Brief description of the drawings]

FIG. 1 is a sectional view showing an embodiment of the present invention.

FIG. 2 is a sectional view showing a conventional configuration.

FIG. 3 is a cross-sectional view showing another conventional configuration.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Transparent electrode film 2 Light emitting layer 3 Insulating layer 4 Back electrode layer

Claims (1)

[Utility model registration claims] A transparent electrode film having a transparent electrode layer formed on an upper surface thereof; a light emitting layer formed on an upper surface of the transparent electrode film; an insulating layer formed on an upper surface of the light emitting layer;
A back electrode layer formed on the upper surface of the insulating layer.
In the L element, the light emitting layer is formed using a cyanoethylated resin as a binder, and the insulating layer and the back electrode layer are formed using a fluorine resin as a binder.