JPH02197080A - Distributed el panel - Google Patents

Abstract

PURPOSE:To keep and show the high emission and the lighting grade easily and maintain the performance for a long term by using the resin having the softening point lower than that of an organic binder of an illuminance layer as an organic binder of an insulating material layer. CONSTITUTION:The paste having the softening point at 140 deg.C is coated on a transference electrode layer 2 to form an illuminant layer 3 integrally and adherently on it, and thereafter, the paste having the softening point at 80 deg.C is coated on the illuminant layer 3 for form an insulating material layer 4 integrally and adherently on it. Further, the Al, foil is themocompression-bonded on the insulating material layer 4 to form a back plate layer 5. A distributed EL panel is thus formed. Since an organic binder having the relatively high softening point is used in the illuminant layer 3, the temperature dependency is restrained, and the dielectric loss is small, and the fine luminance is kept. On the other hand, an organic binder having the relatively low softening point is used in the insulating material layer 4, the fine bonding and the adhesion to the back plate layer 5 is showed.

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Industrial Application Field) The present invention relates to a distributed EL element, and particularly to a distributed EL element with improved lifetime characteristics.

(Prior art) For example, a light source that utilizes the luminescence phenomenon that occurs when a required electric field or voltage is applied to a luminescent layer containing dispersed phosphor particles such as ZnS is shown in Fig. 1 in a cross-sectional view. A distributed EL element (distributed EL device) configured as shown in FIG. 1 is in practical use. That is, for example, I formed on the −1 side of the transparent plastic film I
A transparent electrode layer 2 made of n2O3 or the like, and a luminescent layer 3 integrally disposed on the side of the transparent electrode layer 2. For example, phosphor particles such as ZnS (average particle size of about 20 to 30 μm) are formed in a volume ratio of 40 to 30 μm. a layer formed by dispersing an organic binder having a high dielectric constant of about 80%, for example, a cyanethyl binder;
an insulator layer 4 integrally provided opposite to the light emitting layer 3;
For example, 50 to 90% by volume of high dielectric constant inorganic oxide powder (particle size of several microns or less) such as TiO2 or TiBaO3.
an organic binder having a relatively high dielectric constant, such as a cyanoethyl binder dispersed therein; and the insulating layer 4.
For example, a back electrode layer 5 integrally provided opposite to A
It basically consists of metal foil or metal film such as 1,
If necessary, it is known to further package this with a film having a low moisture permeability, such as a polytrifluorochloroethylene film. However,
This type of distributed EL cord is lightweight.

Because it has features such as thinness, flexibility, and low cost, there is a lot of interest in its use as a backlight for liquid crystal display elements (liquid crystal display devices), for example.

(Problems to be Solved by the Invention) However, the following disadvantages are often found in the distributed EL element having the above configuration. That is, this kind of distributed E
In the L element, in order to respectively constitute the light emitting layer 3 and the insulating layer 4, the same type of organic binder is generally selected as the negative component. for example,
As the organic binder for the light emitter layer 3 and the insulator layer 4, ethyl cyano type or fluorine rubber type is selected. Therefore, it is desired that the light emitting layer 3 has a relatively high softening point from the viewpoint of required luminance and life characteristics. In other words, the luminance and lifetime characteristics of the luminescent layer 3 are easily affected by the dielectric loss and permittivity of the binder, and the organic binder is selected to have a low dielectric loss and a softening point with low temperature dependence. Generally, it has a relatively high softening point. On the other hand, the insulator layer 4 contains inorganic oxide powder with a high dielectric constant dispersed therein, and serves to provide an electric field to the luminescent layer 3, provide insulation between the electrodes 1 and 5, and reflect light from the luminescent layer 3. However, since the high dielectric constant inorganic oxide powder has a smaller particle size than the phosphor in the luminescent layer, when a binder with a high softening point is used, It is often the case that the adhesion or adhesion is poor and the required light emitting function cannot be sufficiently maintained or exhibited over a long period of time.

[Structure of the Invention] (Means for Solving the Problems) The present invention has been made in response to the above circumstances, and in the structure of the dispersion type EL element, a binder having a lower softening point than the organic binder of the light emitting layer is used. The main point is that the organic binder is used as the insulating layer's organic binder. That is, the dispersion type EL element is characterized in that the organic binder of the light emitting layer and the insulating layer are not the same type, but an organic binder with a relatively low softening point is used for the insulating layer.

(Function) According to the above structure of the present invention, since an organic binder with a relatively high softening point is used in the light emitting layer, temperature dependence is suppressed, resulting in low dielectric loss and excellent luminance. and maintain and exhibit long life characteristics. - On the other hand, since an organic binder with a relatively low softening point is used for the insulating layer, it exhibits good adhesion or adhesion to the back electrode layer.

(Example) The present invention will be described in detail below. Distributed EL according to the present invention
The structure of the element itself is basically the same as that shown in FIG. 1 above. That is, at least the back electrode layer 5, the insulator layer 4 containing dispersed inorganic oxide powder with a high dielectric constant, the luminescent layer 3 containing dispersed phosphor particles, and the transparent electrode layer 2
This is a dispersion type EL element formed by sequentially laminating and integrating the above, and is characterized by using a resin having a lower softening point than the organic binder of the light emitting layer 3 as the organic binder of the insulating layer 4, for example: The structure and manufacture are as follows. First, a transparent electrode layer 2 is formed on the entire surface of a transparent plastic film 1 by a vapor deposition method, a coating method, or the like.

Next, cyanoethylated pullulan (
Apply a paste mixed and adjusted so that the volume ratio of Cu-activated ZnS phosphor particles is 60% during the softening temperature (softening point: 140°C), and dry to integrally form a luminescent layer 3 with a thickness of about 50 μm. did. Thereafter, 'r' was added to the luminescent layer 3 in cyanoethylated polyvinyl alcohol (softening point: 80°C).
A paste mixed and adjusted so that the volume ratio of TO 2 powder was 60% was applied and dried to integrally form an insulating layer 4 having a thickness of about 30 μm. Furthermore, a back electrode layer (counter electrode) is formed by thermocompression bonding A1 foil on the insulator layer 4,
A distributed EL element having the structure shown in FIG. 1 was constructed (Example 1).

In the above, a mixed organic binder of cyanoethylated pullulan and cyanoethylated polyvinyl alcohol (softening point 140°C at a mixing volume ratio of 1:1) was used as the organic binder for the luminescent layer 3, but instead of this organic binder, A dispersion type EL device was constructed under the same conditions as above except that a cyanoethylated cornstarch organic binder (softening point: 100° C.) was used (Example 2).

In addition, as a comparative example, a dispersed type was prepared under the same conditions as above, except that the organic binder used for the luminescent layer 3 in Example 1 was used as the organic binder for the luminescent layer 3 and the insulating layer 4. An EL element was constructed (Comparative Example 1).

Further, as the organic binder for the light emitter layer 3 and the insulator layer 4, the organic binder used for the organic binder for the light emitter layer 3 in Example 2 was used, and the TIo in the insulator layer 4 was used.
A dispersion type EL element was constructed under the same conditions as described above, except that a paste prepared by mixing and adjusting the volume ratio of the two powders to 50% was used (Comparative Example 2).

When each of the above-configured distributed EL elements was driven by applying the required voltage, both the distributed EL elements of Examples 1 and 2 showed high luminance and luminous quality (no uneven luminescence). On the other hand, in the case of Comparative Example 1, the light emission quality was poor (uneven light emission occurred), and in the case of Comparative Example 2, the light emission brightness was poor. Further, in each of the examples, the above-mentioned favorable luminance brightness and luminous quality (no uneven luminescence) were maintained even after long-time driving.

In the present invention, if the organic binder used for the light emitting layer 3 is selected to have a softening point of about 120°C or higher, and the organic binder used for the insulator layer 4 is selected to have a softening point of about 40 to 100°C, The above actions and effects can be obtained.

[Effects of the Invention] As described above, the distributed EL element adopting the configuration of the present invention not only easily maintains and exhibits high luminance and luminous quality, but also maintains these excellent functions and performances for a long time ( maintained over a long period of time.

Thus, the distributed type element of the present invention is lightweight and ? jj.

Together with its features such as shape, flexibility, low cost, and ease of manufacture, it can be said to be suitable for backlights for liquid crystal display devices, for example.

[Brief explanation of the drawing]

FIG. 1 is a partial cross-sectional view showing the configuration of a distributed EL element. 1... Transparent electrode layer support (transparent film) 2... Transparent electrode layer 3... Luminescent layer 4... Insulator layer 5... Back electrode layer (counter electrode)

Claims (1)

[Scope of Claims] A dispersed type formed by sequentially laminating and integrating at least a back electrode layer, an insulating layer containing dispersed inorganic oxide powder with a high dielectric constant, a luminescent layer containing dispersed phosphor particles, and a transparent electrode layer. A dispersion type EL device, characterized in that the organic binder of the insulator layer is a resin having a lower softening point than the organic binder of the light emitting layer.