JPH05299178A - El element - Google Patents

Abstract

PURPOSE:To prevent a spark and improve productivity by concurrently forming a current collecting belt and a back electrode so that they are not overlapped each other. CONSTITUTION:A luminescence layer 3 coated with phosphors is formed on a transparent electrode 2 deposited with ITO on a glass substrate, and a reflecting/insulating layer 4 is formed with insulating paste by screen printing on it. A back electrode 6 coated with silver paste by screen printing is formed on the reflecting/insulating layer 4, and a current collecting belt 5 is concurrently formed on the transparent electrode 2. A back plate 7 is stuck to the reflecting/insulating layer 4, and they are closely sealed with sealing resin. The current collecting belt 5 and the back electrode 6 are concurrently formed so that they are not overlapped each other, the dielectric breakdown by a spark is prevented, the manufacturing process is simplified, and productivity can be improved.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an EL device, and more particularly to an EL device having improved reliability due to improved sparks between electrodes.

[0002]

2. Description of the Related Art As a backlight of a display device, an EL element having uniform brightness, light weight and thinness is used. For example, an EL element using a glass substrate on the light emitting surface side is generally a light emitting element in which a transparent electrode, a light emitting layer, a reflective insulating layer, and a back electrode are laminated on a glass substrate, and a back electrode having moisture resistance from the back electrode side. It has a structure in which face plates are laminated and the peripheral edges of the glass substrate and the back plate are hermetically sealed with an adhesive.

In an EL element having such a structure, ITO glass having a conductive film previously provided on one surface of a glass substrate is generally used as a transparent electrode on the substrate. IT
Since the transparent electrode made of O has a higher electric resistance than a metal, a current collecting band made of a conductive paste such as silver paste or copper paste is formed in a strip shape on the periphery thereof. The electrode lead is led to the outside by connecting to the current collecting band and the back electrode.

[0004]

However, the conventional E
When the electrode lead is energized, the L element has a defect that, in some cases, a defect in the light emitting layer or the reflective insulating layer causes a spark between the current collecting band and the back electrode to cause dielectric breakdown.
In order to prevent dielectric breakdown, an insulating layer may be provided between the current collecting band and the light emitting layer as disclosed in Japanese Utility Model Laid-Open No. 3-28695, but with this technique, an extra insulating layer is provided. It is not practical because the number of manufacturing processes is increased because it is further included. Further, since the film thickness is increased only in the current collecting band portion, there is a defect that causes a film thickness defect of the light emitting layer coated and laminated thereon.

Further, apart from the dielectric breakdown, the effective light emitting portion of the EL element is the inner portion surrounded by the current collecting band, so the power consumption of the light emitting portion between the current collecting band and the back electrode is wasted. Has become.

Therefore, the present invention has been made in view of the above circumstances, and it is possible to prevent the spark between the current collecting band and the back electrode, and to make the most of the effective light emitting portion, which is even easier. An EL device that can be manufactured is provided.

[0007]

In an EL device of the present invention, a transparent electrode and a current collecting band are formed on the periphery of the transparent electrode on at least a glass substrate, and a light emitting layer and a reflective insulating layer are formed on the transparent electrode. , And an EL element having a light emitting element in which a back electrode is sequentially laminated, the current collecting band is formed without overlapping the back electrode.

The EL device of the present invention will be described in detail with reference to FIGS. 1, 2 and 3. 1 is a plan view of an EL device according to an embodiment of the present invention as seen from the back plate 8 side, FIG. 2 is a cross-sectional view of the EL device of FIG. 1 seen from the direction A, and FIG. EL
It is sectional drawing which looked at the element from the B direction. In FIG. 1, only the current collecting band 5 and the back electrode 6 between the glass substrate 1 and the back plate 78 are shown by wavy lines, and the other parts are omitted.

As shown in FIG. 2 and FIG.
In the L element, a transparent electrode 2 is formed on a glass substrate 1, and a current collecting band 5 is formed on the transparent electrode 2 so as not to overlap a back electrode 6 to be formed later, and further on the transparent electrode 2. ,
The light emitting layer 3, the reflective insulating layer 4, and the back electrode 6 are laminated in this order to form a light emitting element, and the back plate 7 is laminated from above the back electrode 6,
The rear plate 7 and the glass substrate 1 are hermetically sealed by bonding the peripheral edges thereof with a sealing resin 8. Also, FIG.
As shown by the wavy line, the current collecting band 5 and the back electrode 6 are formed separately from each other so that they do not overlap.

As the glass substrate 1, a normal glass plate such as soda glass or lead glass can be used. Thickness is 0.1-5.0
mm, further considering strength and weight, 0.4 to 1.
It is preferable to use one having a size of about 1 mm. Further, in order to prevent alkali elution from the glass, a film of silica, alumina or the like may be coated.

The transparent electrode 2 is made of ITO, SnO ₂ , In ₂ O ₃
Can be formed by methods such as vacuum deposition, sputtering, sol-gel method, etc., usually several Ω / □ to several thousand Ω
/ □ can be used, but preferably 30 to 30
A material of 0Ω / □ is used. Also, ITO on the glass substrate
The vapor-deposited product is also commercially available.

The current collecting band 5 is formed by using an electrically conductive paste such as Ag paste or Cu paste by a printing technique such as a screen printing method so as not to overlap the position where the back electrode is to be formed. It is formed at the edge (single edge) or the peripheral edge. However, in the present invention, the peripheral portion does not mean the entire circumference but also a single edge portion (end edge portion) as shown in FIG.

The light emitting layer 3 can be formed by applying a paste in which zinc sulfide-based phosphor particles are dispersed in a suitable organic binder to a film thickness of 20 to 60 μm by the same technique as screen printing. Similarly, for the reflective insulating layer 5, a paste in which a powder having a high dielectric constant such as barium titanate is dispersed in an organic binder is applied to a screen printing method in a range of 10 to 30.
It can be formed with a thickness of μm. In this step, the light emitting layer 3
The reflective insulating layer 4 may overlap the collector band 5.

The back electrode 6 can also be formed by a screen printing method using a conductive paste such as Ag paste or carbon paste on the reflective insulating layer 4 so as not to overlap the current collecting band 5. Alternatively, Al, Au or the like may be formed by vapor deposition. Further, in this step, the current collecting band 5 can be formed at the same time as the back electrode 6, and it is preferable to form the current collecting band 5 at the same time because the number of steps can be reduced.

Any material may be used for the back plate 7 as long as it does not allow water to permeate therethrough. For example, a metal foil, a glass plate, or a material obtained by laminating a metal foil with a resin may be used.

The sealing resin 8 may be made of any material as long as it can bond the back plate 7 and the glass substrate 1 to each other. For example, unsaturated polyester, phenol resin, thermosetting resin such as epoxy resin, or hot polyolefin resin. An adhesive such as a melt adhesive can be used.

[0017]

In the EL device of the present invention, the current collecting band does not overlap with the back electrode, so that the voltage is completely applied to the transparent electrode and the back electrode. Therefore, it becomes possible to eliminate the dielectric breakdown due to the spark of the current collector and the back electrode. Furthermore, since the effective light emitting portion of the EL element is only the area where the back electrode is formed, this is equal to the power consumed between the transparent electrode and the back electrode, and wasteful power is required as in the past. Not.

[0018]

EXAMPLE A glass substrate 1 on which ITO was previously deposited as a transparent electrode 2 was prepared, and the transparent electrode 2 was etched into a predetermined pattern.

Zn is formed on the patterned transparent electrode.
A phosphor paste in which S: Cu, Br phosphor was dispersed in cyanoethyl cellulose was applied by a screen printing method so as to have a dry film thickness of about 30 μm to form a light emitting layer 3.

After the light emitting layer 3 was dried, an insulating paste in which barium titanate was dispersed in cyanoethyl cellulose was screen-printed to form the reflective insulating layer 4 so that the dry film thickness was about 15 μm.

After the reflective insulating layer 4 was dried, a silver paste was applied by screen printing to form a back electrode 6 on the reflective insulating layer 4 and a collector band 5 on the transparent electrode 2 at the same time.

Next, the sealing resin 8 is formed on the entire periphery of the glass substrate 1.
Epoxy adhesive is applied as a
The back plate 7 laminated with ET (polyethylene terephthalate) was brought into close contact with the reflective insulating layer and hermetically sealed. A water trapping layer made of, for example, nylon or paper may be provided between the back plate 7 and the back electrode 6 in order to trap water that has penetrated through the adhesive.

[0023]

As described above, since the EL element of the present invention has a structure in which the current collecting band and the back electrode do not overlap each other, that is, the structure in which the effective light emitting portion does not overlap, dielectric breakdown due to spark can be prevented. Yes, it is very reliable. Further, since the current collecting band and the back electrode can be formed at the same time, the number of manufacturing steps is reduced and the productivity is very excellent.

Further, since the current collecting band does not overlap the effective light emitting portion, the upper part of the current collecting band from the end of the light emitting layer can serve as a "margin" for sealing, thereby reducing the margin area compared to the conventional case. You can

In addition, the conventional EL which does not use a glass substrate
In the element, since the current collector on the transparent electrode side is a resin film on which ITO is vapor-deposited, if the current collector is formed at a position that does not overlap the back electrode, the position where the current collector is formed will collapse during pressure bonding. Although there is a drawback that the reliability of the obtained EL element cannot be ensured, the EL element of the present invention uses the glass substrate on which the transparent electrode is formed to form the current collecting band, and thus the current collecting band may collapse. It is possible to provide an EL element having excellent reliability.

[Brief description of drawings]

FIG. 1 is a plan view of an EL device according to an embodiment of the present invention viewed from a back plate side.

FIG. 2 is a cross-sectional view of the EL element of FIG. 1 viewed from the A direction.

FIG. 3 is a cross-sectional view of the EL element of FIG. 1 viewed from the B direction.

[Explanation of symbols]

1 ... Glass substrate 2 ... Transparent electrode 3 ... Light emitting layer 4 ... Reflective insulating layer 5 ... Current collecting band 6 ... Back electrode 7 ... Back Face plate 8 ... Encapsulating resin

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Yoshinori Shimizu 491, Oka, Kaminaka-cho, Anan City, Tokushima Prefecture Nichia Kagaku Kogyo Co., Ltd.

Claims (1)

[Claims] 1. A light emitting device in which a transparent electrode is formed on at least a glass substrate, and a current collecting band is formed on the periphery of the transparent electrode, and a light emitting layer, a reflective insulating layer, and a back electrode are laminated in that order from above. An EL element having the current collector band formed so as not to overlap the back electrode.