JPH10134963A - Electroluminescent lamp and its manufacture - Google Patents

Abstract

PROBLEM TO BE SOLVED: To bond a light emitting layer made of resin whose hardening point is hardly determined or is equal to or more than 200 deg.C, easily over to a transparent conductive film excellently in adhesive properties without being lowered in brightness by means of thermo compression bonding by way of an intermediate layer made out of conductive thermoplastics whose softening point is less than 200 deg.C. SOLUTION: A reflection insulating layer 2 is formed over a back face electrode 1 formed out of an aluminum foil and the like, a light emitting layer 3 comprising fluorescent material 3a dispersed in resin whose softening point is hardly determined or is equal to or more than 200 deg.C, is printed so as to be formed in order, and ink material formed out of resin whose softening point is less than 200 deg.C, and of transparent conductive powder, is coated over the light emitting layer 3 up to the thickness of 1 to 3μm so as to allow an intermediate layer 4 whose surface resistance value is 10<4> to 10<8> Ω/square. And furthermore, a transparent conductive film 5 on which a transparent electrode 5b such as an ITO and the like is formed over a transparent film 5a, is bonded over the intermediate layer 4 by means of thermal adhesion with pressure, so that the electroluminesce lamp can thereby be obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electroluminescent lamp and a method of manufacturing the same, and more particularly to an electroluminescent lamp having an intermediate layer interposed between a transparent conductive film and a light emitting layer to improve adhesion and withstand voltage, and to manufacture the same. It is about the method.

[0002]

2. Description of the Related Art Conventionally, an electroluminescent lamp 30 has a back electrode 3 made of aluminum foil or the like as shown in an enlarged sectional view of a main part of FIG.
1, a reflective insulating layer 32 and a light emitting layer 33 are sequentially laminated and printed,
In general, a transparent conductive film 34 in which a transparent electrode 34b is formed on a transparent film 34a is attached to the light emitting layer 33 by thermocompression bonding. Here, the resin generally used for the light emitting layer has a high dielectric constant, and when the transparent conductive film 34 and the light emitting layer 33 are thermocompression-bonded, the heat resistance of the transparent film 34a which is the base material of the transparent conductive film 34 is reduced. Considering that the treatment is performed at a temperature of 200 ° C. or less, a resin such as cyanoethyl pullulan having a low softening point is used. Further, a fluorine-based resin having low hygroscopicity is preferable.

[0003]

However, in the above structure,
When a fluorinated resin is used for the light emitting layer, the phosphor used is as large as 20 to 50 μm, the affinity between the fluororesin and the phosphor is poor, and the light emitting layer after printing is difficult to level, so the light emitting layer has irregularities. Since it is in a state and the fluorine-based resin does not have a softening point and is not thermoplastic, a sheet obtained by laminating and printing a reflective insulating layer and a light emitting layer on an aluminum foil cannot be bonded to a transparent conductive film by thermocompression bonding. There was a problem. Similarly, cyanoethylcellulose could not be bonded by thermocompression bonding because of its high softening point.

[0004] In order to solve these problems, Japanese Utility
No. 26720 and Japanese Utility Model Application Laid-Open No. 2-73091 disclose a structure in which a light emitting layer is provided with a resin layer on a transparent conductive film to improve the adhesion between the transparent conductive film and the light emitting layer. Since is an insulating material, there are problems that the intensity of the electric field applied to the light emitting layer is reduced and the luminance is reduced, and that unevenness in light emission occurs if the resin layer is not applied uniformly. Japanese Utility Model Application Laid-Open No. 2-62697 discloses a structure in which a transparent conductive resin layer is interposed between a light emitting layer and a transparent conductive film, but the surface resistance of the transparent conductive resin layer is in the order of 10 ² Ω / □. Therefore, there is a problem in that, when the fixed-size cutting is performed, the back electrode and the transparent conductive resin layer are electrically connected by sagging, thereby causing a short circuit.

[0005]

Means for Solving the Problems The present invention solves the above-mentioned problems, and even if a light emitting layer is laminated and formed using a resin having no softening point or having a softening point of 200 ° C. or higher, a transparent conductive film is formed thereon. It has been proposed for the purpose of providing an electroluminescent lamp that can be attached by thermocompression bonding, improves luminance reduction, and prevents short-circuiting at the time of fixed-size cutting. In an electroluminescent lamp in which a light emitting layer and a reflective insulating layer are disposed between, between the transparent electrode and the light emitting layer,
A transparent conductive powder comprising at least one of indium oxide, tin oxide and tin oxide to which antimony is added;
℃ than consisting lower thermoplastic resin surface resistance of 10 ⁴ -
It is characterized in that an intermediate layer of 10 ⁸ Ω / □ is interposed.

Further, a reflective insulating layer on the back electrode, a light emitting layer using a resin having no softening point or having a softening point of 200 ° C. or more, a surface resistance of 10 ⁴ to 10 ⁸ Ω / □ and a softening point of 20
A thermoplastic intermediate layer having a temperature lower than 0 ° C. is sequentially laminated, and a transparent conductive film is bonded thereon by thermocompression bonding.

According to the present invention, since a thermoplastic and conductive intermediate layer is formed on the light-emitting layer, the light-emitting layer using a resin having no softening point or having a softening point of 200 ° C. or more can be used. It can be easily and thermally bonded to the transparent conductive film without lowering the luminance. In particular, the adhesiveness of a fluorine resin having low moisture permeability or cyanoethyl cellulose having good heat resistance is improved, and the characteristics and reliability under high temperature and high humidity can be improved. The surface resistance of the intermediate layer is 10 ⁴ to 10 ⁸ Ω.
/ □, there is no short circuit due to sagging of the back surface electrode or the intermediate layer when cutting to a fixed length. Further, the unevenness of the light emitting layer is reduced by the intermediate layer, the adhesion to the transparent conductive film is improved, and the light emitting quality can be improved.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The electroluminescent lamp of the present invention is characterized in that an intermediate layer made of a conductive resin having a softening point lower than 200 ° C. is interposed between a light emitting layer and a transparent conductive film. This intermediate layer is a mixture of a resin having thermoplasticity (for example, an acrylic resin) and a transparent conductive powder.
As the conductive powder, one or more of tin oxide, indium oxide, tin oxide to which antimony is added, and the like are preferable.

By interposing the intermediate layer, even if a resin having no softening point or a resin having a softening point of 200 ° C. or more is used as the resin used in the light emitting layer, the transparent conductive film can be adhered to the transparent conductive film by thermocompression bonding. Can be glued. For this reason, characteristics unique to these resins can be utilized and an electroluminescent lamp having high characteristics and high reliability can be provided. For example, when fluororubber is used, the hygroscopicity is low, so that the luminance under high humidity is improved. When cyanoethylcellulose is used, the luminance under high temperature is improved.

The intermediate layer has a surface resistance of 10 ⁴ to 10.
⁸ Ω / □ is formed by mixing the materials, so when the electroluminescent lamp is cut to a fixed size and completed, it will be electrically short-circuited even if the back electrode and the intermediate layer make contact due to sagging. Nothing.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A first embodiment of the electroluminescent lamp according to the present invention will be described with reference to FIG. Electroluminescent lamp 10 of the present invention
As shown in the cross-sectional view of FIG. 1A, first, a white high dielectric substance such as barium titanate is coated on a back electrode 1 made of aluminum foil or the like with a low hygroscopic resin such as fluoro rubber (for example, Daikin Industries, Ltd.). A reflective insulating layer 2 dispersed in a G501 manufactured by Co., Ltd., and a phosphor 3a in which zinc sulfide is activated with copper is coated thereon with a moisture-proof coating (for example, Sylvania phosphor TYPE.2).
0) is dispersed in a low hygroscopic resin such as fluororubber (for example, G501 manufactured by Daikin Industries, Ltd.) to form a light emitting layer 3 by printing. At this time, the phosphor has a large particle size of 20 to 50 μm, and the affinity between the fluororesin and the phosphor is poor, and it is difficult to perform leveling.
As shown in the main part enlarged cross-sectional view of (b), unevenness occurs, and the surface roughness d (difference between the concave portion and the convex portion) is about 25 μm.

Next, an ink obtained by dispersing and mixing a thermoplastic resin (for example, an acrylic resin) having a softening point lower than 200 ° C. and a transparent conductive powder composed of tin oxide and indium oxide on the light emitting layer 3 is 1 to 3 μm. And the surface resistance is about 10
An intermediate layer 4 of ⁶ Ω / □ is formed. By coating the intermediate layer 4 on the light emitting layer 3, the surface of the light emitting layer 3 is smoothed as shown in FIG. 1 (c), and the surface roughness d becomes a smooth surface state reduced to 8 to 10 μm. .

Next, a transparent conductive film 5 in which a transparent electrode 5b of ITO or the like is formed on the transparent film 5a is adhered on the intermediate layer 4 by thermocompression to obtain an electroluminescent lamp 10. Middle layer 4
Since is a thermoplastic and smooth film, the transparent conductive film 5 can be easily attached by thermocompression bonding. Further, the light emitting layer 3 and the transparent conductive film 5 are completely electrically connected with the intermediate layer 4 interposed therebetween. Because of the connection, a uniform electric field is applied to all the phosphors, and high-quality light emission can be obtained.

Next, FIG. 2 shows the relationship between the surface resistance of the intermediate layer and the luminance, and FIG. 3 shows the relationship between the surface resistance of the intermediate layer and the breakdown voltage ratio. As described above, the lower the surface resistance value of the intermediate layer, the smaller the resistance loss and the higher the brightness, but the higher the probability of short-circuiting due to sagging of the intermediate layer and burrs of the aluminum foil as the back electrode, and the occurrence rate of withstand voltage failure increases. Get higher. In order to lower the surface resistance, the concentration of the transparent conductive powder in the ink may be increased. However, since the transparent conductive powder is very expensive, it is disadvantageous in cost. Therefore, the surface resistance of the intermediate layer is particularly preferably 10 ⁴ to 10 ^{8 in} consideration of the luminance, the breakdown voltage ratio, and the cost.
Ω / □ is desirable.

Next, the electroluminescent lamp 10 obtained in the first embodiment
The characteristics of FIG. 4 shows the life characteristics of the electroluminescent lamp 10 according to the present invention under high humidity in comparison with a conventional example. Here, the electroluminescent lamp of the conventional structure uses cyanoethyl pullulan as a resin for the light emitting layer and has no intermediate layer. In addition, the electroluminescent lamp of the present invention is in the state of a moisture-proof outer film, and the conventional structure was comparatively evaluated for the presence or absence of a moisture-proof outer film. As described above, the electroluminescent lamp of the present invention using the fluororubber having no softening point as the resin for the light-emitting layer allows the light-emitting layer and the transparent conductive film to be securely bonded by thermocompression by interposing the intermediate layer. Therefore, even without a moisture-proof outer film, it is possible to obtain the same life characteristics as a conventional structure provided with an outer film by making use of the low moisture absorption of fluororubber, without using an expensive outer film. Thus, a highly reliable electroluminescent lamp can be provided at low cost.

Next, a second embodiment of the present invention will be described. In the first embodiment, an example is described in which a low moisture-absorbing fluorine resin is used for the resin used for the light emitting layer, and the reliability under high humidity is improved by thermocompression bonding to the transparent conductive film via the intermediate layer. In the second embodiment, an example will be described in which a resin having a high softening point can be used to improve the life characteristics at high temperatures.

FIG. 5 is a sectional view of an electroluminescent lamp 20 according to a second embodiment of the present invention. First, a reflective insulating layer 12 in which a white high dielectric substance such as barium titanate is dispersed in a low hygroscopic resin such as fluoro rubber is formed on a back electrode 11 made of aluminum foil or the like, and zinc sulfide is formed thereon. A phosphor (for example, Sylvania phosphor TYPE.723) activated with copper is dispersed in cyanoethylcellulose (for example, CR-C manufactured by Shin-Etsu Chemical Co., Ltd.) which is softened at a high temperature of 270 ° C. or more to form a print. Next, an ink obtained by dispersing and mixing a thermoplastic resin (for example, an acrylic resin) having a softening point of 50 to 70 ° C. and a transparent conductive powder made of tin oxide and indium oxide is applied to the light emitting layer 13 at 1 to 3 μm. Then, the intermediate layer 14 is formed. Further, a transparent conductive film 15 in which a transparent electrode 15b of ITO or the like is formed on the transparent film 15a is stuck on the intermediate layer 14 by thermocompression to obtain an electroluminescent lamp 20.

Next, the electroluminescent lamp 20 obtained in the second embodiment
The characteristics of FIG. 6 shows the life characteristics of the electroluminescent lamp 20 at a high temperature. Here, the conventional electroluminescent lamp shown for comparison has a structure in which cyanoethyl pullulan is used as the resin of the light emitting layer and there is no intermediate layer. However, both were evaluated in a state sealed with a moisture-proof outer skin film. As described above, by using a resin having a high softening point and excellent heat resistance for the light emitting layer, the permittivity of the resin is increased at a high temperature, and as a result, the life characteristics at a high temperature such as a high luminance are significantly improved. be able to.

As the transparent conductive powder, "tin oxide +
In addition to "indium oxide", tin oxide alone, indium oxide alone, or tin oxide to which antimony is added may be used alone. Especially in the case of tin oxide with antimony added,
This is more cost effective than “tin oxide + indium oxide”. The solvent for the intermediate layer used in the present invention may be an organic solvent-based solvent or an aqueous solvent.

[0020]

According to the present invention, since a thermoplastic and conductive intermediate layer having a softening point lower than 200 ° C. is interposed on the light emitting layer, there is no softening point or the softening point is 200 ° C.
A light-emitting layer using a resin having a temperature of not less than ° C. can be easily adhered to a transparent conductive film with good adhesion by thermocompression bonding without lowering luminance. Accordingly, there is no limitation on the resin used for the light emitting layer, and the characteristic reliability under high humidity or high temperature can be improved by utilizing the characteristics of the resin. Further, since the surface resistance of the intermediate layer is 10 ⁴ to 10 ⁸ Ω / □, there is no short circuit due to sagging of the back electrode or the intermediate layer when cutting to a fixed length. further,
The unevenness of the light emitting layer is reduced by the intermediate layer, the adhesion to the transparent conductive film is improved, and the light emitting quality can be improved. Also, even if the transparent electrode is disconnected, the conductive layer is maintained conductive because the conductive intermediate layer is present,
An inexpensive and high-quality electroluminescent lamp can be provided.

[Brief description of the drawings]

FIG. 1 is a sectional view of an electroluminescent lamp showing a first embodiment of the present invention.

FIG. 2 is a diagram showing the relationship between the surface resistance value and the luminance of the intermediate layer of the electroluminescent lamp according to the first embodiment of the present invention.

FIG. 3 is a diagram showing the relationship between the surface resistance value of the intermediate layer of the electroluminescent lamp according to the first embodiment of the present invention and the breakdown voltage failure rate.

FIG. 4 is a diagram showing the life characteristics of the electroluminescent lamp according to the first embodiment of the present invention.

FIG. 5 is a sectional view of an electroluminescent lamp according to a second embodiment of the present invention.

FIG. 6 is a view showing a life characteristic of an electroluminescent lamp according to a second embodiment of the present invention.

FIG. 7 is a sectional view showing a conventional electroluminescent lamp.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1,11 Back electrode 2,12 Reflective insulating layer 3,13 Light emitting layer 3a Phosphor 4,14 Intermediate layer 5,15 Transparent conductive film 5a, 15a Transparent film 5b, 15b Transparent electrode (ITO etc.) 10,20 Electroluminescent lamp

Claims (4)

[Claims] 1. An electroluminescent lamp in which a light emitting layer and a reflective insulating layer are provided between a transparent electrode and a back electrode, wherein a surface resistance between the transparent electrode and the light emitting layer is 10 ⁴ to 10 ⁸ Ω / □. And
An electroluminescent lamp characterized by interposing a thermoplastic intermediate layer having a softening point lower than 200 ° C. 2. The electroluminescent lamp according to claim 1, wherein the intermediate layer contains a transparent conductive powder of at least one of indium oxide, tin oxide and tin oxide to which antimony is added. 3. A reflective insulating layer on a back electrode, a light emitting layer using a resin having no softening point or having a softening point of 200 ° C. or more,
A method for manufacturing an electroluminescent lamp, comprising sequentially laminating an intermediate layer having a surface resistance of 10 ⁴ to 10 ⁸ Ω / □ and having thermoplasticity, and pasting a transparent conductive film thereon by thermocompression bonding. 4. The method according to claim 3, wherein the resin used for the light emitting layer is a fluororesin or cyanoethyl cellulose.