JP2719559B2 - EL element - Google Patents

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 conventionally used, a light emitting layer, an insulating layer, and a light emitting layer are formed on a transparent electrode film formed by depositing a transparent electrode layer made of ITO on a polyethylene terephthalate (PET) film. The back electrode layer was laminated thereon, and the laminate was sealed by sandwiching both sides of the laminated body with a moisture-proof film. The light-emitting layer 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 high dielectric binder. Have been. The insulating layer 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 was composed of carbon powder, silver powder, copper powder, or a mixture of these powders and polyester as a binder.

[0003] The structure of the EL element in the prior art described above is such that the thickness of each moisture-proof film is about 200 to 300.
μm, and occupies approximately half of the thickness of the entire EL element.
Both the thickness and the outer shape of the moisture-proof film became large.

[0004] In contrast to a conventional general EL element in which both surfaces are sandwiched by a moisture-proof film, by eliminating the need to sandwich both surfaces by a moisture-proof film, the thickness is reduced so that the outer shape is reduced. The EL elements for which miniaturization has been attempted are:
As shown in FIG. 7, 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 fluorine resin as a binder for forming the light emitting layer 12 and the insulating layer 13.
In any 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, a conventional EL element having a moisture-proof film sandwiched on both sides, which has been conventionally used, can cope with a tendency to miniaturize a device to which the element is mounted. There are no weaknesses. For this reason, attempts have been made to reduce the size of EL elements used in precision equipment such as watches and clocks.

[0006] The EL element is susceptible to moisture, and quickly degrades if no measures are taken against moisture. In the EL element using a fluororesin as a binder for the light emitting layer and the insulating layer, the fluororesin has extremely high water repellency among the resins, and the EL due to invasion of moisture from the outside.
Although extremely resistant to element deterioration, the transparent electrode film and the back electrode are exposed at the end face of the EL element, and are exposed to the external environment. Therefore, the EL element deteriorates from the end face. Had the problem of doing so.

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to prevent deterioration from an end face of an EL element in which a fluororesin is used as a binder for a light emitting layer and an insulating layer, and both sides are not pinched by a moisture proof film. And

[0008]

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

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

As a second means, the light emitting layer in the first means is formed to be smaller than the transparent electrode film by a size, and its end face is covered with an insulating layer to ensure protection of the light emitting layer. I have.

As the third means, the first means or the second means
The back electrode layer in the means is formed of a highly water-repellent fluororesin as a binder to improve the moisture-proof effect.

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 highly water-repellent fluororesin layer.

[0013]

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

(Embodiment 1) FIG.
Example 1 of an L element is shown.

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 1.

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 the phosphor 2a constituting 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 produce a luminescent ink. This luminescent ink is printed on the ITO vapor-deposited surface by a method such as a screen printing method, and then heated and dried to form the luminescent layer 2.

Next, an insulating layer 3 is formed on the light emitting layer 2 by the same method as the formation of the light emitting layer 2. The insulating ink forming the insulating layer 3 is barium titanate (BaTiO ₃ ).
It is made by mixing and stirring 60 g of a high dielectric substance made of and 35 g of the above-mentioned fluororesin binder. The back electrode layer 4 prints carbon ink on the insulating layer 3,
It is formed by heating and drying. Here, the feature of the present invention resides in that the back electrode layer 4 is formed one size smaller than the insulating layer 3. The carbon ink is formed by mixing carbon powder with 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.

FIG. 2 shows that the EL element of this structure is
The top view seen from the side is shown. The width A shown in the figure corresponds to the portion where the back electrode layer 4 is formed to be smaller than the insulating layer 3 by one turn, and thus serves as a 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 one size smaller than the insulating layer 3 is shown in Samples ad shown in Table 1 below (sample a has a width of 0). Various EL devices are manufactured at 40 (° C.) 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 end face of the EL element was deteriorated as shown in FIG.

[0020]

[Table 1]

It is apparent from the results shown in FIG. 3 that the provision of the non-light-emitting portion on the end face of the EL element can prevent the deterioration from the end face of the EL element.

(Embodiment 2) As shown in FIG.
Is such that the light emitting layer 2 provided in the same area as the transparent electrode film 1 in Example 1 is formed to be smaller than the transparent electrode film 1 by one turn, and the end face is covered with the insulating layer 3. is there. The other back electrode layer 4 is the same as that of the first embodiment. The EL element configured as in the present embodiment is inferior to the first embodiment in the complexity of the manufacturing process, but is excellent in the effect of protecting the light emitting layer 2 from intrusion of moisture.

(Embodiment 3) As shown in FIGS. 5 (a) and 5 (b), the embodiment 3 is similar to the embodiment 1 shown in FIG.
(B) shows a case in which the back electrode layer 4 of Example 2 is replaced by a back electrode layer 5 formed of a high dielectric substance and a fluororesin, and has a further protective effect against the intrusion of moisture into the light emitting layer 2. It is intended.

The back electrode layer 5 used in the third embodiment 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
Is dissolved in 25 g of methyl ethyl ketone, and these are mixed and stirred to produce a carbon ink.
This carbon ink was printed on the insulating layer 3 of Example 1 or Example 2, and heated and dried to form the back electrode layer 5.

Example 4 FIGS. 6A, 6B, 6C and 6D show an EL device of Example 4. FIG. The fourth embodiment is different from the first to third embodiments in that the insulating layer protrudes from the back electrode layer 4 or 5 or from the periphery of the back electrode layer 4 or 5 and the back electrode layer 4 or 5. The protective layer 6 made of a fluororesin is formed on the substrate 3 to achieve a further protective effect against intrusion of moisture. The thickness of this protective layer 6 is about 1
0 μm, the thickness of the conventional moisture-proof film is about 200
It does not significantly affect the thickness of the EL element as compared with a thickness of up to 300 μm. FIG. 6 shows an application example to the first embodiment.
(A), an application example to the second embodiment is FIG. 6 (b), and an application example to the third embodiment is FIG. 6 (c) and (d).

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 applying the fluororesin ink on the back electrode layer 4 or 5. The back electrode layer 4 or 5 and the insulating layer 3 protruding from the periphery of the back electrode layer 4 or 5 are printed by screen printing or the like, and are heated and dried to form a protective layer 6 made of a fluororesin layer.

[0027]

Other Embodiments In this embodiment, a binder obtained by dissolving 10 g of a copolymer of vinylidene fluoride and propylene hexafluoride in 25 g of methyl ethyl ketone has been used as a fluororesin binder for forming the light emitting layer 2 and the insulating layer 3. Examples have been given, but as the fluororesin binder,
As a polymer of vinylidene fluoride, polyvinylidene fluoride or vinylidene fluoride and another fluororesin, for example,
A copolymer of at least one of ethylene fluoride, vinyl fluoride, ethylene trifluoride, ethylene trifluoride chloride, ethylene tetrafluoride, and propylene hexafluoride may be used.

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

As the phosphor 2a, ZnS doped with Cu was used.
A material coated with an inorganic transparent dielectric material such as O ₂ , TiO ₂ or Ai ₂ O ₃ may be used.

[0030]

According to the structure of the present invention, deterioration of the EL element in which the end faces are exposed is prevented by eliminating the need to hold the both faces with the moisture-proof film, and as a result, the long-term operation is prevented. It is possible to maintain high display quality throughout.

Further, the light emitting layer constituting the EL element is formed to be smaller than the transparent electrode film by one size and its end face is covered with an insulating layer, the back electrode layer is formed by using a fluorine resin as a binder, or the back electrode layer is formed. By covering the layer and the insulating layer exposed from the edge of the back electrode layer with a fluororesin layer, the protection of the light emitting layer can be further ensured.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view illustrating a configuration of a first embodiment.

FIG. 2 is a plan view of Example 1 as viewed from a back electrode side.

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

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

5A and 5B are cross-sectional views illustrating a configuration of a third embodiment, in which FIG. 5A illustrates an example applied to the first embodiment, and FIG. 5B illustrates an example applied to the second embodiment.

FIGS. 6A and 6B are cross-sectional views illustrating a configuration of a fourth embodiment. FIG. 6A is an example applied to the first embodiment, FIG. 6B is an example applied to the second embodiment, and FIGS. Example 3 is shown below.

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

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Transparent electrode film 2 Light emitting layer 2a Phosphor 3 Insulating layer 4 Back electrode layer 5 Back electrode layer (fluororesin binder) 6 Protective layer

 ──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-6-338393 (JP, A) JP-A-6-52988 (JP, A) JP-A-7-85974 (JP, A) JP-A-2- 227991 (JP, A) JP-A-3-216998 (JP, A) JP-A-63-290993 (JP, A) JP-A-2-57596 (JP, U) JP-A-1-86096 (JP, U) Actual opening 1988-188896 (JP, U)

Claims (4)

(57) [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;
E comprising the 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 using a highly water-repellent fluororesin as a binder, and the back electrode layer is formed to be smaller than the insulating layer by one size. 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, an insulating layer formed on the upper surface of the light emitting layer,
E comprising the 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 using a highly water-repellent fluororesin as a binder, and the light emitting layer is formed to be smaller than the transparent electrode film by one size, and an end face thereof is formed. An EL element covered with the insulating layer, wherein the back electrode layer is formed to be smaller than the insulating layer by one size. 3. The EL device according to claim 1, wherein the back electrode layer is formed using a fluorine resin having high water repellency as a binder. 4. The EL according to claim 1, 2 or 3.
An EL element, wherein the back electrode layer and the insulating layer exposed from an edge of the back electrode layer are covered with a highly water-repellent fluororesin layer.