JPH0785969A - El element - Google Patents

Abstract

PURPOSE:To make an EL element small and thin by eliminating the use of any anti-moistening film. CONSTITUTION:A light emitting layer 2 is provided on the oversurface of a transparent electrode film 1, and thereover an insulation layer 5 which uses as binder a fluoric resin having anti-moistening effect, and further thereover a back electrode layer 7 is formed which uses fluoric resin as a binder. Fluoric resin layers 8b, 8c having anti-moistening effect are formed on the outside surface of the film 1 (top in the attached illustration) and the oversurface of the back electrode layer 7 (bottom). Because moisture prevention of the light emitting layer 2 is made by the fluoric resin and the fluoric resin layer, sealing with a conventional anti-moistening film is no more needed, which has caused enlargement of the thickness and contour. The anti-moistening effect of the light emitting layer will be further enhanced by allowing the fluoric resin layer to serve solely for moisture prevention so that the insulative layer and back electrode layer are made free from fluoric resin, according to the use conditions of EL element, or by forming a moisture absorbing layer on the oversurface of the back electrode layer which are than sealed totally with fluoric resin layer.

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 shown in FIG. 8, a general EL element which has been conventionally used is formed by depositing a transparent electrode layer made of ITO on a polyethylene terephthalate (PET) film on a transparent electrode film 11. The light emitting layer 12, the insulating layer 14, and the back electrode layer 16 are laminated on the light emitting layer 12, the insulating layer 14, and the both sides of these laminated layers are sandwiched by the moisture-proof films 20 and 20 to be sealed.

The light emitting layer 12 is composed of zinc sulfide (ZnS) and Cu.
A phosphor powder doped with an activator such as Mn and Mn and an activator such as Cl is dispersed in a high dielectric binder of cyanoethylated cyanoethylated compound. The insulating layer 14 is barium titanate (BaTiO ₃ ).
And a high-dielectric material such as a cyanoethylated cyanoethylated product dispersed in a high-dielectric binder.
The back electrode layer 16 is composed of carbon powder, silver powder, copper powder, and a mixed powder of these and polyester as a binder.

In the above-mentioned conventional structure, each of the moisture-proof films 20 and 20 has a thickness of about 200 to 300.
It is μm, occupies about half of the total thickness of the EL element, and the outer shape also needs to have a minimum of about 1 mm for each portion to be joined in the periphery, so that both the thickness and the outer shape are large.

As described above, the EL element in the prior art has a weak point that it cannot fully cope with the trend toward miniaturization of equipment in which the EL element is mounted. Therefore, attempts have been made to reduce the size of EL elements used in precision instruments such as watches.

FIG. 9 shows an example of an attempt to reduce the size of an EL element. By using a fluorine resin 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, Improves 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 and 30 provided on the outer surface of the transparent electrode layer 21 and the upper surface of the back electrode layer 26, and the EL having excellent durability is also provided. It is intended to be used as an element (JP-A-57-63797).

[0007]

DISCLOSURE OF THE INVENTION In the prior art,
The sealing with a moisture-proof film improves the durability of the light emitting layer, but is more disadvantageous in terms of thickness and external size. In particular, it is disadvantageous in terms of size when incorporated in a small device such as a watch. On the other hand, in the case of using a fluororesin as a binder for a high-dielectric material, it can be dealt with in terms of reducing the size of the outer shape, but it still requires a moisture-proof film on both sides, so it is insufficient to support miniaturization. Is. Further, since the fluororesin has a lower dielectric constant than the high dielectric binder of cyanoethylated cyanoethylated compound,
There is a disadvantage that a sufficient amount of light emission cannot be obtained.

It is therefore an object of the present invention to provide an EL element having a small outer shape and a small thickness, and having a light emission amount having a function equivalent to that provided with a moisture-proof film.

[0009]

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. The back electrode layer is formed on the upper surface of the insulating layer, and the fluororesin layer is formed on both surfaces or the outer surface of the transparent electrode film and the outer surface of the back electrode layer.

As the second means, the insulating layer in the first means is made of a high dielectric material having a fluororesin as a binder, and the formation of the fluororesin layer on the outer surface of the back electrode layer is omitted to reduce the cost. There is.

As the third means, the back electrode layer in the first means is made of a conductor having a fluororesin as a binder, and the formation of the fluororesin layer is omitted as in the second means.

As a fourth means, the insulating layer in the first means is made of a high dielectric material having a fluororesin as a binder, and at the same time, the back electrode layer is made of a conductor having a fluororesin as a binder to protect the light emitting layer. To ensure.

As a fifth means, a hygroscopic layer made of a hygroscopic substance is formed between the back electrode layer and the fluororesin layer formed on the outside thereof, and the hygroscopic layer is not exposed by the fluororesin layer. By covering it, a reliable moisture-proof effect is achieved.

[0015]

In the first means described above, since the fluororesin layer, which is a highly moisture-proof substance, is formed on both surfaces or the outer surface of the transparent electrode layer and the outer surface of the back electrode layer, sealing with a moisture-proof film is required. Not.

In the second means, since the insulating layer is made of a high dielectric material using a fluororesin, which is a highly moisture-proof substance, as a binder, fluorine on the outer surface of the back electrode layer formed in the first means is used. By eliminating the need for forming a resin layer, the number of manufacturing steps can be reduced.

In the third means, instead of the insulating layer in the second means, the back electrode layer is made of a conductor having a fluororesin as a binder, so that the outer surface of the back electrode layer is the same as in the second means. The formation of the fluororesin layer is unnecessary.

The fourth means employs all of the above-mentioned first to third means, and the best moistureproof effect can be realized.

In the fifth means, a moisture absorbing layer is formed on the outer surface of the back electrode layer in the first means or the outer surface of the back electrode layer in the fourth means, and the whole is covered with a fluororesin layer to form a light emitting layer. To further improve the moisture-proof effect of.

[0020]

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

(Embodiment 1) FIG. 1 shows an EL in this embodiment.
The structure of Example 1 of an element is shown.

A fluororesin layer 8a having a thickness of about 10 μm is formed between the transparent electrode film 1 and the light emitting layer 2, and a fluororesin layer 8b having the same thickness is formed on the opposite surface of the transparent electrode film 1. Has been formed. An insulating layer 4 is formed on the upper surface of the light emitting layer 2, and a back electrode layer 6 is formed on the upper surface thereof. Further, on the back electrode layer 6, a fluororesin layer 8c is formed similarly to the upper surface of the transparent electrode film 1. After all, the fluororesin layer is formed in three layers as a whole, and the total thickness thereof is about 30 μm.

The fluororesin layer 8 is prepared by dissolving 10 g of a copolymer of vinylidene fluoride and propylene hexafluoride in 30 g of methyl ethyl ketone to prepare a fluororesin ink, and printing the ink on the forming surface by screen printing or the like and heating.
It is formed by drying.

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

The luminescent layer 2 is formed by printing luminescent ink on the upper surface of the fluororesin layer 8a on the lower surface of the transparent electrode film 1. Cu-doped zinc sulfide (ZnS) is used as the phosphor forming the luminescent ink. 60 g of this phosphor and, as a binder, 10 g of cyanoethylated cellulose, which is a highly dielectric substance, is dissolved in 25 g of propylene carbonate as a solvent in advance, and these are mixed to prepare a luminescent ink. This luminescent ink is attached to the upper surface of the fluororesin layer 8a by a method such as a screen printing method, and this is heated and dried to form the luminescent layer 2.

Similar to the fluororesin layer 8a, a fluororesin layer 8b is formed on the side of the transparent electrode film 1 opposite to the surface in contact with the light emitting layer 2 (upper surface in FIG. 1).

Next, the insulating layer 4 is formed on the light emitting layer 2 by the same method as that for forming the light emitting layer 2. The insulating ink for forming the insulating layer 4 is composed of barium titanate (BaTiO ₃ ) 60 g of a high dielectric substance and the high dielectric binder 3 described above.
It is made by mixing and stirring 5 g.

The back electrode layer 6 is formed by printing carbon ink on the insulating layer 4. The carbon ink is composed of a mixture of carbon powder and polyester as a binder. In addition to this, the back electrode layer 6 is
It may be composed of carbon powder and silver powder, copper powder and polyester as a binder.

Finally, a third fluororesin layer 8c is formed on the back electrode layer 6 to complete the EL device.

The EL element formed in this way has two layers
A fluororesin layer 8a is provided between the transparent electrode film 1 and the light emitting layer 2 on the front side of the transparent electrode film 1 and the back electrode layer 6 without providing a moisture-proof film having a total thickness of about 500 μm. By forming it, it becomes possible to prevent moisture from entering the light emitting layer. Therefore, if the device incorporating the EL element has a certain degree of airtightness, this EL
The element ensures sufficient reliability.

Incidentally, the water absorption of the fluororesin 8 is 0.04.
%, Which is a remarkable difference of 1/50 or less as compared with 2% of cyanoethylated cellulose, and functions sufficiently as a protective layer against the intrusion of water into the light emitting layer 2.

As to the dielectric constant of the EL element provided with the fluororesin layer 8 as described above, as shown in the following calculation example, it is comparable to that of the high dielectric binder, and the light emitting property is high. Is not inferior in terms of.

The dielectric constant (ε) synthesized by the fluororesin layer 8a and the light emitting layer 2 is equal to the dielectric constant of the fluororesin layer.
₁ , the layer thickness is d ₁ , the dielectric constant of the high dielectric material of the light emitting layer is ε ₂ , and the layer thickness is d ₂ , ε = ε ₁ ε ₂ (d ₁ + d ₂ ) / (ε ₁ It is given by d ₂ + ε ₂ d ₁ ).

In the above equation, ε ₁ = 13 (at 120 Hz), ε
₂ = 17.5 (same) and d ₁ = 10 μm, d ₂ = 30 μ
If m is set and this is calculated by the above formula, the calculation result is 16.1
Therefore, ε is slightly smaller than ε ₂ = 17.5, and has little effect on luminance.

In this embodiment, the following may be taken as a means for further thinning the EL element.

(Embodiment 2) As shown in FIG.
Is intended to reduce the cost by omitting the fluororesin layer 8a formed between the transparent electrode film 1 and the light emitting layer 2 in Example 1. Other insulating layer 4, back electrode layer 6
Alternatively, the fluororesin layers 8b and 8c are formed on the outside of the electrode layers in the same manner as in Example 1. The EL element constructed according to this example is inevitably a little inferior in the protection effect against the intrusion of moisture into the light emitting layer 2, but it is a trade-off with the life and brightness of the EL element and the airtightness of the device itself incorporating the EL element. If you select with, the effect can be fully demonstrated.

(Embodiment 3) As shown in FIG.
Replaces the insulating layer in Example 1 with an insulating layer 5 formed of a high dielectric substance and a fluororesin layer, and the back electrode layer 6
The formation of the fluororesin layer 8c formed on the upper side of is omitted, and it is aimed at further thinning and cost reduction.

The high dielectric material forming the insulating layer 5 is BaTi.
Insulating ink is prepared by mixing and stirring 60 g of O ₃ with a binder prepared by dissolving 10 g of a copolymer of vinylidene fluoride and propylene hexafluoride in 25 g of methyl ethyl ketone in advance. This insulating ink is printed on the light emitting layer 2, and the insulating layer 5 containing a fluororesin binder is formed by heating and drying.

The fluorine-based binder at this time has a lower dielectric constant than that of cyanoethylated cellulose, but BaTi
Since the dielectric constant of O ₃ is very high (1800 (F / m)), the difference in the dielectric constant of the fluorine-based binder does not cause a great difference in the brightness of the EL element.

Since the insulating layer 5 prevents moisture from entering the light emitting layer 2, the durability of the EL element is not affected even if the fluororesin layer is not formed on the upper surface of the back electrode layer 6. Therefore, the same effect as that of the first embodiment is obtained. In this embodiment, since no change is made to the light emitting layer 2, it does not affect the brightness of the EL element. Therefore, moisture can be prevented from entering the light emitting layer without the moistureproof film and the fluororesin layer 8c on the back electrode side, which contributes to downsizing and cost reduction of the EL element.

(Embodiment 4) As shown in FIG.
Replaces the back electrode 6 (see FIG. 2) in Example 2 with a back electrode layer 7 composed of carbon powder as a conductor and a fluororesin binder, and in the same manner as in Example 3, the fluororesin layer 8c on the back electrode side is formed. The formation is omitted.

Specifically, 30 g of carbon powder is mixed with a binder prepared by dissolving 20 g of a copolymer of vinylidene fluoride and propylene hexafluoride in 50 g of methyl ethyl ketone in advance to prepare a carbon ink. This carbon ink is printed on the insulating layer 4, heated and dried to form the back electrode layer 7.

(Embodiment 5) As shown in FIG.
Is an insulating layer 5 using the fluororesin as a binder in Example 3 (see FIG. 3), a back electrode 7 using the fluororesin in Example 4 as a binder (see FIG. 5), and a fluororesin layer 8c in Example 1 (see FIG. (See 1)) is provided at the same time. On the upper surface side (lower surface in FIG. 5) of the light emitting layer 2, the moisture-proof effect by the fluororesin becomes large, and the shape and thickness become smaller and the brightness becomes higher, so that it is the best configuration functionally. As a manufacturing method, each layer may be formed according to each of the above-described examples.

The insulating layer 4 of the first embodiment (see FIG. 1) is replaced with the insulating layer 5 of the fluororesin of the third embodiment + a binder of high dielectric material, or the back electrode layer 6 (see FIG. 1). By replacing the reference) with the back electrode layer 7 formed of the carbon powder and the fluororesin of Example 4,
It is also possible to obtain an EL element having high durability.

Example 6 As shown in FIGS. 6 and 7, a moisture absorption layer 9 is provided on the back electrode layer 6 or 7 of Examples 2 and 5,
By sealing this with a fluororesin layer 8d, the moisture-proof effect is improved.

The hygroscopic layer 9 is formed by printing an ink prepared by mixing a starch-based hygroscopic substance and a binder in which acrylic or polyester is dissolved in a solvent, followed by heating and drying. By forming the fluororesin layer 8d so as to cover the moisture absorption layer 9, the moisture absorption layer 9 is sealed to enhance the effect of preventing moisture from entering the light emitting layer 2.

[0047]

According to the present invention, as a means for preventing moisture in the light emitting layer, an extremely thin fluororesin layer is formed in place of the conventionally used moisture-proof film. It is possible to downsize the EL element without impairing the brightness of.

Further, when the insulating layer is made of a high dielectric material and a fluororesin as a binder, a sufficient moistureproof effect for the light emitting layer can be obtained even if the formation of the fluororesin layer formed on the back electrode layer is omitted. It is possible to reduce the thickness of the E
It is possible to obtain the L element at low cost.

Similarly, the same effect can be obtained by forming the back electrode layer from a conductor and a fluororesin as a binder.

Further, if the insulating layer and the back electrode layer are made of the above-mentioned fluororesin as a binder and further the fluororesin layer is formed on the upper surface of the back electrode layer, the moisture-proof effect of the light emitting layer is excellent. A small and thin EL element can be obtained at the same time that the above effect is exhibited.

Further, if a hygroscopic layer is provided on the upper surface of the back electrode layer and the hygroscopic layer is covered with a fluororesin and sealed, it is somewhat disadvantageous in terms of thickness and cost.
It is possible to obtain an EL element having an excellent moistureproof effect on the light emitting layer.

[Brief description of drawings]

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

FIG. 2 is a cross-sectional view showing a configuration of a second embodiment.

FIG. 3 is a cross-sectional view showing a configuration of a third embodiment.

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

FIG. 5 is a cross-sectional view showing the structure of a fifth embodiment.

FIG. 6 is a cross-sectional view showing the structure of a sixth embodiment.

FIG. 7 is a cross-sectional view showing the configuration of Example 7.

FIG. 8 is a cross-sectional view showing a configuration of a conventional example.

FIG. 9 is a cross-sectional view showing the configuration of another conventional example.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Transparent electrode film 2 Light emitting layer 4,5 Insulating layer 6,7 Back electrode layer 8 (8a-8d) Fluororesin layer 9 Moisture absorption layer

Claims (5)

[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.
An EL device comprising a back electrode layer formed on the upper surface of the insulating layer, and a fluororesin layer formed on both surfaces or the outer surface of the transparent electrode film and the outer surface of the back electrode layer. 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.
A back electrode layer formed on the upper surface of the insulating layer and a fluororesin layer formed on the outer surface of the transparent electrode film are provided, and the insulation layer is made of a high dielectric material using a fluororesin as a binder. An EL device characterized by the above. 3. 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.
A back electrode layer formed on the upper surface of the insulating layer and a fluororesin layer formed on the outer surface of the transparent electrode film are provided, and the back electrode layer is made of a conductor having a fluororesin as a binder. An EL device characterized by the above. 4. A transparent electrode film having a transparent electrode layer formed on an upper surface thereof, a light emitting layer formed on the upper surface of the transparent electrode film, and 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; and a fluororesin layer formed on the outer surface of the transparent electrode film and on the outer surface of the back electrode layer, wherein the insulating layer is a fluororesin binder. The back electrode layer is composed of a dielectric,
An EL element comprising a conductor having a fluororesin as a binder. 5. The hygroscopic layer formed of a hygroscopic substance is formed between the back electrode layer and the fluororesin layer according to claim 1, wherein the hygroscopic layer is the fluororesin. An EL device, which is covered with a layer so that it cannot be exposed.