JPH07106064A - El element - Google Patents

Abstract

PURPOSE:To prevent the deterioration of an EL element from the end surface thereof by using fluororesin having a high volatility as a binder in a light emitting layer and an insulating layer formed in order on a transparent electrode, and forming a back plate layer on the insulating layer a little smaller than the insulating layer. CONSTITUTION:ITO is vapor-deposited on a polyethylene terephthalate film to form a transparent electrode film l. The top surface of this film 1 is printed with the light emitting ink obtained by mixing phosphor 2a in the binder made of copolymer, which is composed of vinylidene fluoride and propylene hexafluoride, by screen printing or the like. An insulating layer 3 is formed by the similar method with the insulating ink obtained by mixing high dielectric material made of barium titanate in the described binder made of fluororesin. A back plate layer 4 is formed on the insulating layer 3 a little smaller than the insulating layer 3 by printing with the carbon ink, and heating it for drying. Deterioration of an EL element from the end surface can be thereby prevented without coating both surfaces with moisture-proof film.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an EL device.

[0002]

2. Description of the Related Art As a general EL element which has been conventionally used, a light emitting layer, an insulating layer and a transparent electrode film formed by depositing a transparent electrode layer made of ITO on a polyethylene terephthalate (PET) film are provided. The back electrode layer was laminated on top, and both sides of these laminated ones were sandwiched with a moisture-proof film for sealing. The light emitting layer is composed of zinc sulfide (ZnS) in which an activator such as Cu or Mn and an activator such as Cl are doped and dispersed in a cyanoethylated cyanoethylated high dielectric binder. Has been done. The insulating layer is formed by dispersing a high dielectric material such as barium titanate (BaTiO ₃ ) in a high dielectric binder of cyanoethylated cyanoethylated compound. The back electrode layer was composed of carbon powder, silver powder, copper powder, and a mixture of these powders and polyester as a binder.

The structure of the EL element in the above-mentioned prior art is such that each of the moisture-proof films has a thickness of about 200 to 300.
μm, which occupies about half of the total thickness of the EL element, and requires about 1 mm at the minimum for the outer joints of the moisture-proof film.
Both the thickness and the outer shape of the moisture-proof film had become large.

Therefore, in contrast to the conventional general EL element in which both sides are sandwiched by moisture-proof films, by eliminating sandwiching both sides by moisture-proof films, the thickness becomes thin and the outer shape becomes small. The EL elements that have been tried to be downsized are
As shown in FIG. 7, in order, a transparent electrode film 11 having a transparent electrode layer formed on the upper surface, a light emitting layer 12, an insulating layer 13,
It is known that a back electrode 14 is provided and a moisture-proof effect is obtained by using a fluororesin as a binder for forming the light emitting layer 12 and the insulating layer 13.
In all of these, the back electrode layer 14 formed on the insulating layer 13 has the same area as the insulating layer 13, and the entire EL element emits light.

[0005]

As described above, the conventional EL element having both surfaces sandwiched by the moisture-proof film, which has been conventionally used, cannot cope with the trend toward miniaturization of equipment to which the EL element is mounted. There are no weaknesses. For this reason, attempts have been made to reduce the size of EL elements used in precision instruments such as watches.

The EL element is vulnerable to moisture and will be deteriorated immediately if some measures against moisture are not taken. In the EL element in which the fluororesin is used as the binder of the light emitting layer and the insulating layer, the fluororesin has extremely high water repellency among the resins, and EL due to the intrusion of moisture from the outside
Although it is extremely strong against deterioration of the element, the EL element deteriorates from its end surface because the transparent electrode film and the back electrode are exposed at the end surface of the EL element and exposed to the external environment. It had a problem that it did.

Therefore, an object of the present invention is to prevent the deterioration from the end face portion of the EL element without sandwiching the both surfaces of which the fluorine resin is used as the binder of the light emitting layer and the insulating layer with the moistureproof film. And

[0008]

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

As a first means thereof, a transparent electrode film having a transparent electrode layer formed on the upper surface thereof, a light emitting layer formed on the upper surface of the transparent electrode film, and an insulating layer formed on the upper surface of the light emitting layer, In an EL element including a back electrode layer formed on the upper surface of the insulating layer, the light emitting layer and the insulating layer are formed by using a highly water-repellent fluororesin as a binder, and the back electrode layer is a layer closer than the insulating layer. It is formed small.

As a second means, the light emitting layer in the first means is formed to be slightly smaller than the transparent electrode film, and the end face portion is covered with an insulating layer to ensure the protection of the light emitting layer. There is.

As the third means, the first means or the second means
By forming the back electrode layer in the means using a fluororesin having high water repellency as a binder, the moisture-proof effect is improved.

As the fourth means, the first means or the second means
A reliable moisture-proof effect is achieved by covering the back electrode layer and the insulating layer exposed from the edge of the back electrode layer in the means or the third means with a fluororesin layer having high water repellency.

[0013]

Embodiments of the present invention will be described below with reference to the drawings.

(Embodiment 1) FIG. 1 shows E in this embodiment.
Example 1 of an L element is shown.

The transparent electrode film 1 is composed of a film made of polyethylene terephthalate (PET) on which ITO forming a transparent electrode film is vapor deposited to form a transparent conductive film 1.

The luminescent layer 2 is formed by printing luminescent ink on the upper surface of the transparent electrode film 1. Cu-doped zinc sulfide (ZnS) is used as the phosphor 2a forming the luminescent ink. 60 g of this phosphor 2a and 10 g of a copolymer of vinylidene fluoride and propylene hexafluoride as a fluororesin binder were added to methyl ethyl ketone 2
Using a binder dissolved in 5 g, these are mixed and stirred to make a luminescent ink. This luminescent ink is printed on the ITO vapor deposition surface by a method such as screen printing, and then heated and dried to form the luminescent layer 2.

Next, the insulating layer 3 is formed on the light emitting layer 2 by the same method as that for forming the light emitting layer 2. The insulating ink that forms the insulating layer 3 is barium titanate (BaTiO ₃ ).
It is made by mixing 60 g of a high dielectric substance composed of the above and 35 g of the above-mentioned fluororesin binder and stirring. The back electrode layer 4 is formed by printing carbon ink on the insulating layer 3,
It is formed by heating and drying. Here, the present invention is characterized in that the back electrode layer 4 is formed to be slightly smaller than the insulating layer 3. The carbon ink is composed of a mixture of carbon powder and polyester as a binder. In addition, the back electrode layer 4 may be composed of carbon powder, silver powder, copper powder, and polyester as a binder.

In FIG. 2, the EL element of this structure is shown in the back electrode layer 4
The top view seen from the side is shown. The width A shown in the figure corresponds to the amount by which the back electrode layer 4 is formed to be slightly smaller than the insulating layer 3, and thus serves as the non-light emitting portion of the EL element of this embodiment.

As an embodiment of the present invention, the width A in which the back electrode layer 4 is formed to be slightly smaller than the insulating layer 3 is shown in Tables 1 to 3 below (Samples a to d have a width of 0). We made various EL elements in 40 (℃) 90 (% R
When the EL element was caused to emit light in the atmosphere of (H) under the conditions of 100 (V) and 400 (Hz), the deterioration of the end face portion of the EL element resulted in the result shown in FIG.

[0020]

[Table 1]

From the results shown in FIG. 3, it is apparent that the deterioration from the end surface portion of the EL element can be prevented by providing the non-light emitting portion on the end surface portion of the EL element.

(Embodiment 2) As shown in FIG.
Is a light-emitting layer 2 provided in the same area as the transparent electrode film 1 in Example 1 is formed to be slightly smaller than the transparent electrode film 1, and the end face portion thereof is covered with the insulating layer 3. is there. The other back electrode layers 4 are the same as those in the first embodiment. The EL device configured as in this example is inferior to that in Example 1 in terms of the manufacturing process, but is excellent in the effect of protecting moisture from entering the light emitting layer 2.

(Embodiment 3) As shown in FIGS. 5 (a) and 5 (b), Embodiment 3 is similar to FIG.
In (b), the back electrode layer 4 of Example 2 is replaced with a back electrode layer 5 formed of a high dielectric substance and a fluororesin, and a protective effect against moisture intrusion into one light emitting layer 2 is further provided. It is intended.

The back electrode layer 5 used in Example 3 is
It is composed of carbon powder and fluororesin. Specifically, 30 g of carbon powder and 10 g of a copolymer of vinylidene fluoride and propylene hexafluoride as a fluororesin binder
Using a binder in which 25 g of methyl ethyl ketone is dissolved, these are mixed and stirred to prepare a carbon ink.
This carbon ink is printed on the insulating layer 3 of Example 1 or Example 2, heated and dried to form the back electrode layer 5.

(Embodiment 4) An EL element given as Embodiment 4 is shown in FIGS. 6 (a), 6 (b), 6 (c) and 6 (d). Example 4 is an insulating layer protruding from the back electrode layer 4 or 5 or around the back electrode layer 4 or 5 and the back electrode layer 4 or 5 in the EL element in the example 1 or 2 or 3. The protective layer 6 made of a fluororesin is formed on the surface of the protective layer 3 in order to further protect the moisture from entering. The thickness of this protective layer 6 is about 1
0 μm, the thickness of the conventional moisture-proof film is about 200
The thickness of the EL element is not significantly affected as compared with the thickness of 300 μm. An example of application to the first embodiment is shown in FIG.
6A is an example of application to (a) and the second embodiment, and FIGS. 6C and 6D are examples of application to the third embodiment.

The protective layer 6 made of a fluororesin is prepared by dissolving 10 g of a copolymer of vinylidene fluoride and propylene hexafluoride in 25 g of methyl ethyl ketone to prepare a fluororesin ink, and the fluororesin ink is formed on the back electrode layer 4 or 5 or A protective layer 6 made of a fluororesin layer is formed by printing by screen printing or the like on the back electrode layer 4 or 5 and the insulating layer 3 protruding from the periphery of the back electrode layer 4 or 5 and heating and drying.

[0027]

OTHER EXAMPLE In this example, a binder prepared by dissolving 10 g of a copolymer of vinylidene fluoride and propylene hexafluoride in 25 g of methyl ethyl ketone was used as a fluororesin binder for forming the light emitting layer 2 and the insulating layer 3. Although examples have been given, as the fluororesin binder,
As a polymer of vinylidene fluoride, polyvinylidene fluoride or vinylidene fluoride and other fluororesins, for example,
Any one or more copolymers of ethylene fluoride, vinyl fluoride, ethylene trifluoride, ethylene trifluoride chloride, tetrafluoroethylene, and hexafluoropropylene may be used.

Further, as the fluororesin used as the binder for the back electrode layer 5 and the protective layer 6, ethylene fluoride, vinyl fluoride, vinylidene fluoride, ethylene trifluoride, ethylene trifluoride chloride, ethylene tetrafluoride, Any two or more copolymerizable copolymers of propylene hexafluoride and polymers with those monomers may be used.

As the phosphor 2a, ZnS doped with Cu was used.
O _2, may also be used coated with a transparent dielectric inorganic, such as TiO _2, Ai ₂ O _3.

[0030]

According to the structure of the present invention, it is possible to prevent deterioration from the end surface portion of an EL element in which the end surface portion is exposed without sandwiching both surfaces with a moisture-proof film, and as a result, long-term It is possible to maintain high display quality throughout.

Further, the light emitting layer constituting the EL element is formed to be slightly smaller than the transparent electrode film, and its end face portion is covered with an insulating layer, the back electrode layer is formed with a fluororesin as a binder, or the back electrode is formed. By covering the layer and the insulating layer exposed from the edge of the back electrode layer with a fluororesin layer, the light emitting layer can be protected more reliably.

[Brief description of drawings]

FIG. 1 is a sectional view showing a configuration of a first embodiment.

FIG. 2 is a plan view of the first embodiment viewed from the back electrode side.

FIG. 3 is a measurement result of deterioration of an end surface portion of an experiment performed in Example 1.

FIG. 4 is a cross-sectional view showing a configuration of a second embodiment.

5A and 5B are cross-sectional views showing a configuration of Example 3, where FIG. 5A shows an example applied to Example 1 and FIG. 5B shows an example applied to Example 2.

6A and 6B are cross-sectional views showing a configuration of Example 4, where FIG. 6A is an example applied to Example 1, FIG. 6B is an example applied to Example 2, and FIGS. An example applied to No. 3 is shown.

FIG. 7 is a cross-sectional view showing a configuration of a conventional example.

[Explanation of symbols]

 1 Transparent Electrode Film 2 Light Emitting Layer 2a Phosphor 3 Insulating Layer 4 Back Electrode Layer 5 Back Electrode Layer (Fluorine Resin Binder) 6 Protective Layer

Claims (4)

[Claims] 1. A transparent electrode film having a transparent electrode layer formed on the upper surface, a light emitting layer formed on the upper surface of the transparent electrode film, and an insulating layer formed on the upper surface of the light emitting layer.
E comprising a back electrode layer formed on the upper surface of the insulating layer
In the L element, the light emitting layer and the insulating layer are formed by using a fluororesin having high water repellency as a binder, and the back electrode layer is formed to be slightly smaller than the insulating layer. element. 2. A transparent electrode film having a transparent electrode layer formed on the upper surface, a light emitting layer formed on the upper surface of the transparent electrode film, and an insulating layer formed on the upper surface of the light emitting layer.
E comprising a back electrode layer formed on the upper surface of the insulating layer
In the L element, the light emitting layer and the insulating layer are formed by using a fluororesin having high water repellency as a binder, the light emitting layer is formed to be slightly smaller than the transparent electrode film, and the end face portion thereof is An EL element, which is covered with the insulating layer, wherein the back electrode layer is formed to be slightly smaller than the insulating layer. 3. The EL element according to claim 1 or 2, wherein the back electrode layer is formed using a fluororesin having high water repellency as a binder. 4. The EL according to claim 1, 2 or 3.
In the device, the back electrode layer and the insulating layer exposed from the edge of the back electrode layer are covered with a fluororesin layer having high water repellency.