JPH0636878A - Electroluminescent element - Google Patents

Abstract

PURPOSE:To provide excellent moisture resistance by forming a light emitting layer by dispersing a phosphor in a thermosetting resin having a low water absorptivity. CONSTITUTION:A dielectric paste obtained by dispersing a dielectric 2a of barium titanate in a thermosetting resin 2b having a low water absorptivity which consists of an epoxy resin is applied onto an aluminium foil 1, and dried to form a dielectric layer 2. On the other hand, a light emitting layer 5 is applied onto a transparent electrode 4 consisting of ITO formed on a transparent polyester film 3, and dried. For the light emitting layer 5, a light emitting body paste obtained by dispersing a phosphor 5a consisting of an activating agent of copper and, as occasion demands, an activating agent of chlorine into a thermosetting resin 5b having a low water absorptivity is used. The foil 1 is opposed to the film 3 so that the dielectric layer 2 makes contact with the light emitting layer 5, and after heated and pressurized, these are sealed by a moisture preventing film 6. A thermosetting high dielectricity resin layer may be provided on the surface of the phosphor followed by capsulation.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electroluminescent device for use in a lighting environment such as an automobile instrument, particularly in a humid environment.

[0002]

2. Description of the Related Art In general, a light emitting layer in a dispersion type electroluminescent device is a phosphor obtained by doping a base material such as zinc sulfide with an activator such as copper (if necessary, an activator such as chlorine is added). It was formed by being dispersed in a high dielectric constant binder resin (binder), and as the binder, cyanoethylated pullulan, cyanoethylated cellulose, cyanoethylated PVD, etc. were used (JP-A-3-250582).

[0003]

However, this type of light emitting layer has a problem in moisture resistance because the light emitting life is remarkably shortened by water absorption. In general, the entire electroluminescent device may be covered with a moisture-proof film such as a polymer film (Japanese Patent Laid-Open No. 4-13
8688), and a water-absorbing film is interposed so as to prevent moisture permeating the moisture-proof film from being transmitted to the light-emitting layer.
4-169093 gazette) etc. had to be taken.

Alternatively, ceramics or glass is used as a binder, and a fluorescent substance is dispersed in the binder (Japanese Patent Laid-Open No. 3-30083).
No. 238793) is also proposed, but it is difficult to uniformly disperse the fluorescent substance in the binder, and therefore, there is a problem that it is difficult to obtain uniform light emission.

[0005]

In order to solve the above-mentioned problems, the present invention is characterized in that it is a light-emitting layer in which a fluorescent substance is dispersed in a thermosetting resin having a low water absorption coefficient. Furthermore, the fluorescent substance is further provided. It is characterized in that a thermosetting high dielectric constant resin layer is provided on the surface of and encapsulated.

[0006]

In the electroluminescent device of the present invention having a light emitting layer in which a fluorescent substance is dispersed in a thermosetting resin having a low water absorption, the light emitting layer has a low degree of water absorption, and therefore the emission life is not shortened. Further, the electroluminescent element of the present invention having a phosphor light emitting layer in which a thermosetting high dielectric constant resin layer is provided on the surface of the phosphor is used to emit light by the high dielectric constant resin around the phosphor. Is enhanced, and light emission with good brightness can be obtained.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The electroluminescent device of the present invention will be described below based on each embodiment shown in the accompanying drawings.

FIG. 1 shows the structure of the main part of the first embodiment, in which a dielectric material 2a of barium titanate is made of epoxy resin (Kayatron L-850P manufactured by Nippon Kayaku Co., Ltd.) on an aluminum foil 1. The dielectric paste dispersed in the thermosetting resin 2b having a low temperature was applied by screen printing and dried to form the dielectric layer 2.

On the other hand, a light emitting layer 5 is applied by screen printing on a transparent electrode 4 made of indium tin oxide (ITO) formed on a transparent polyester film 3.
The light-emitting layer 5 is formed by drying, but the phosphor 5a made of a zinc sulfide base material, a copper activator, and optionally a chlorine activator is used as the light-absorbing layer 5 having the same water-absorbing property as the thermosetting resin 2b of the dielectric layer 2. The luminous body paste dispersed in the thermosetting resin 5b having a low rate was used.

Then, the aluminum foil 1 and the polyester film 3 are opposed to each other so that the dielectric layer 2 and the light emitting layer 5 are in contact with each other, and these are heat-pressed, and then sealed with a moisture-proof film 6 of a trifluoroethylene chloride film. did.

In the electroluminescent device having such a structure, since the light emitting layer 5 has excellent moisture resistance, the conventionally used water-absorbing film can be omitted, and the moisture-proof film 6 need not be expensive as in the conventional case. Not only good but can be omitted depending on the usage environment.

FIG. 2 shows the structure of the main part of the second embodiment. If the same parts as those in the first embodiment are designated by the same reference numerals and detailed description thereof is omitted, a dielectric layer is formed on the aluminum foil 1. 2 and the light emitting layer 5 are sequentially laminated, and a transparent electrode layer 7 made of coating type ITO (see JP-A-63-10496) is further formed on the light emitting layer 5 and sealed with a moisture-proof film 6. ing. Also in this electroluminescent device, the same effect as in the above-described embodiment can be obtained, and the moisture-proof film 6 can be omitted.

FIG. 3 is an enlarged view of the light emitting layer 5 of the third embodiment, in which a thermosetting high dielectric constant resin layer 5c of cyanoethylated pullulan or the like is provided on the surface of the phosphor 5a to encapsulate it. The light-emitting layer 5 is formed by being dispersed in a thermosetting resin 5b having a low water absorption rate.

With this structure, since the high-dielectric-constant resin layer 5c is provided around the fluorescent body 5a, the electric field applied to the fluorescent body 5a is strengthened, and the electric field is superior in light emission brightness to the first and second embodiments. A light emitting device can be obtained.

In addition to the structure of the third embodiment, the dielectric layers 2 and the light emitting layer 5 are alternately laminated in plural layers in the first and second embodiments as a structure for increasing the emission brightness. Forming is also effective. Further, it is possible to combine the third embodiment with this plural laminated structure. As the thermosetting resins 2b and 5b, resins such as melanin, urea and phenol can be appropriately selected and used.

[0016]

The present invention is characterized in that it is a light-emitting layer in which a fluorescent substance is dispersed in a thermosetting resin having a low water absorption coefficient. Further, a thermosetting high dielectric constant resin is provided on the surface of the fluorescent substance. It is characterized by providing a layer and encapsulating it, and since the light emitting layer has excellent moisture resistance, it is suitable for use in lighting environments such as automobile instrument lighting sources, especially in places where humidity is severe, and has been used conventionally. The water-absorbing film can be omitted, and the moisture-proof film need not be expensive as in the past, and can be omitted depending on the use environment, and the structure of the electroluminescent device can be simplified.

Further, in contrast to the conventional one in which ceramics or glass is used as a binder and the fluorescent substance is dispersed therein,
The present invention, in which the phosphor is initially dispersed in a liquid thermosetting resin and then the light emitting layer is stabilized by heating, is easy to uniformly disperse the phosphor in the entire light emitting layer, and thus uniform light emission is achieved. Easy to get.

Further, the light-emitting layer of the fluorescent body, in which the high dielectric constant resin layer is provided on the surface of the fluorescent body and is encapsulated, enhances the light emission and makes it possible to obtain light emission of good brightness.

[Brief description of drawings]

FIG. 1 is a sectional view of an essential part of a first embodiment of the present invention.

FIG. 2 is a sectional view of a main part of a second embodiment of the present invention.

FIG. 3 is an enlarged sectional view of a light emitting layer according to a third embodiment of the present invention.

[Explanation of symbols]

 5 Light Emitting Layer 5a Fluorescent Material 5b Thermosetting Resin with Low Water Absorption 5c Thermosetting High Dielectric Constant Resin Layer

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Ryuji Igarashi 1-1190, Fujihashi, Nagaoka City, Niigata Prefecture 1 R & D Center, Nippon Seiki Co., Ltd. (72) Inventor Zhang Yiei Fujihashi, Nagaoka City, Niigata Prefecture 1-chome 190 1 Nippon Seiki Co., Ltd. R & D Center

Claims (2)

[Claims] 1. An electroluminescent device comprising a light emitting layer in which a phosphor is dispersed in a thermosetting resin having a low water absorption rate. 2. The electroluminescent device according to claim 1, wherein a thermosetting resin layer having a high dielectric constant is provided on the surface of the fluorescent body for encapsulation.