JP2824451B2 - EL light emitting device - 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 in which a flexible printed cable is connected to an EL element.

[0002]

2. Description of the Related Art As will be described later, there are various types of EL elements having a total thickness of about 1 mm to several mm.
EL elements of various shapes are used as EL light emitting devices. In any case, since the EL element emits light by applying a voltage to the light emitting layer by the transparent electrode and the back electrode, it is necessary to connect both of these electrodes to the terminal cable. In recent EL elements, a moisture-proof film is not provided on the outermost layer on the back side, the transparent electrode layer is exposed around the light emitting layer, and a flexible printed cable is brought into contact with the exposed portion of the transparent electrode layer and the back electrode layer. In addition, there has been proposed a device in which connection is performed by thermocompression bonding via a conductive hot melt material.

However, in the case of thermocompression bonding using a hot melt material, there is a disadvantage that adjacent terminals arranged in a plane on a flexible printed cable are easily short-circuited, so that the terminal arrangement pitch cannot be made dense. To address this, it is proposed to provide a parallel conductive path on one surface of the insulating sheet as a flexible printed cable and connect it with a heat-sealable flexible printed cable provided with a hot melt layer in a predetermined range from the end of the cable. (JP-B-63-31904). When connecting a parallel conductive path to an EL element or the like of the other party, this heat-sealable flexible printed cable is configured such that the terminal electrode of the other party is opposed to these parallel conductive paths and pressed under heating using a pressing jig. To join the two. This pressing bends to form a concave groove extending in a direction intersecting these conductive paths, and at the same time, melts with the hot melt layer and removes it from the pressed position, thereby directly connecting the parallel conductive paths and the electrode terminal portions. The EL element and the flexible printed cable are physically connected to each other while being electrically connected and solidifying the molten hot melt material.

[0004]

The connection between the EL element and the flexible printed cable in the prior art described above depends only on the adhesive strength of the hot melt material. Since only the intersecting sections of the parallel conductive paths to be connected are thermocompression-bonded, there is a problem that they are weak against external force and cause a failure. Furthermore, when the flexible printed cable is brought into contact with the electrode terminal portion of the EL element, it is inevitable that a projection will be formed only at that portion, and when handling, it will be peeled off by external force such as contact with surrounding objects. There was a problem.

An object of the present invention is to provide an EL light emitting device in which the connection strength between an EL element and a flexible printed cable is enhanced so that the EL element is not easily damaged by an external force.

[0006]

In order to achieve the above object, in the EL light emitting device of the present invention, a transparent electrode layer is formed on the back side of a base film, and a portion around the transparent electrode layer is transparent. An EL element in which a light emitting layer, an insulating layer, and a back electrode layer are sequentially laminated on the back surface of the transparent electrode layer other than the exposed portion, and one side is abutted on the back side of the EL element, and thermocompression bonding is performed. in EL light-emitting device comprising a flexible printed cable is connected by flexible
The shibble print cable has two strips on one side of the insulating sheet.
Are formed in parallel and the back of the EL element
Hot melt layer and heat resistance
Resin layers are formed alternately, and both conductive paths are
And the transparent electrode exposed part, and interposed between them.
The hot-melt material is removed from the flexible printed cable, and a reinforcing sheet is attached to the back of the flexible printed cable so as to cover the periphery of the flexible printed cable to the EL element.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS As shown in FIG. 2, an EL element which is a main part of an EL light emitting device of the present invention has a transparent electrode layer 2 on the back side of a substantially square base film 1. Is formed. The base film 1 is made of a polyethylene terephthalate (PET) film and has a thickness of 0.05
It has a thickness of about 0.2 mm. Also,
The transparent electrode layer 2 is made of indium tin oxide (IT
O) to a thickness of several μm.

On the back surface of the transparent electrode layer 2, a light emitting layer 3 is formed with a transparent electrode exposed portion 2a of a predetermined width left around. The light-emitting layer 3 is made of zinc sulfide (ZnS) as a phosphor.
Is formed by screen printing using a printing ink obtained by mixing and agitating a fluorine-based resin binder having high moisture proofness with copper (Cu) being doped.

On the back surface of the light emitting layer 3, an insulating layer 4 having the same size as that of the insulating layer 4 is formed. The insulating layer 4 is formed by screen printing using a printing ink obtained by mixing and stirring the same binder used for the light emitting layer 3 with powder of barium titanate (BaTiO ₃ ), which is a high dielectric material. .

On the back surface of the insulating layer 4, a back electrode layer 5 is formed to have a size in which the periphery thereof is slightly recessed from the periphery of the insulation layer 4. The back electrode layer 5 is also formed by screen printing using a printing ink obtained by mixing and stirring the same binder as the binder used for the light emitting layer 3 with the carbon powder.

The transparent electrode exposed portion 2a has an electrode portion 6 formed by printing with the same printing ink as the back electrode layer 5. Since the electrode portion 6 has a relatively large electric resistance of ITO constituting the transparent electrode layer 2, the terminal for local connection has insufficient conductivity. It forms a high carbon electrode layer. The electrode portion 6 is formed by printing together with the back electrode layer 5 when printing. On the back surface of the electrode part 6, a silver paste 7 constituting a connection terminal part is formed. Also,
Similarly, on the back surface of the back electrode layer 5, a silver paste 8 is formed in a belt shape slightly receding from the periphery. Each silver paste 7, 8
Are formed to increase the conductivity between the conductive path and each electrode layer when a flexible printed cable described later is connected.

Next, the flexible printed cable F connected to the EL element will be described. As shown in FIG.
On one surface (upper surface) of the insulating sheet 9, two conductive paths 10
Are provided in parallel. The conductive path 10 is formed by printing the same printing ink as that of the back electrode layer 5 of the EL element described above. On the conductive path forming surface of the insulating sheet 9,
A hot melt layer (not shown) and a heat-resistant resin layer (not shown) are alternately formed in a lattice. The hot melt layer is formed by screen printing using a polyester-based thermoplastic resin material as a printing ink. The hot melt layer has an insulating property, and functions as an adhesive by melting when heated. The heat-resistant resin layer is printed using a printing ink made of a polyester-based resin material having insulation properties and considerably higher heat resistance than the hot-melt layer.

The conductive path forming surface of the flexible printed cable F is opposed to a part of the rear surface of the EL element E, and one conductive path 10a and the silver paste 8 on the upper surface of the back electrode layer 5 are in contact with each other, and the other conductive path 10b And the silver paste 7 on the transparent electrode exposed portion 2a are brought into contact with each other so that the hot melt material interposed therebetween is eliminated. On the other hand, the opposing surfaces of the one conductive path 10a and the silver paste 7 and the other conductive path 10b and the silver paste 8 are in an insulated state because the heat-resistant resin layer is interposed therebetween.

The flexible printed cable F is connected to the EL element E at a predetermined position. A heating iron is applied to the EL element E from the outside of the flexible printed cable F in the direction of the EL element E, and the silver pastes 7 and 8 are connected to the flexible printed cable F. The surfaces facing the print cable F are simultaneously pressed. Then, the portion facing the hot melt layer is removed from the pressed portion by heat and pressure around the portion, and one conductive path 10a and silver paste 8 and the other conductive path 10b and silver paste 7 Abuts. At this time, the removed hot-melt agent of the hot-melt layer solidifies around the conductive paths 10a and 10b and the silver bases 7 and 8, and has a strong adhesive action.

On the other hand, the portion of the flexible printed cable F which faces the heat-resistant resin layer maintains its state even when subjected to such heat pressurization, and the conductive path 10 and the silver paste 7, 8 Is kept in a non-contact state. Thus, the EL element E is connected to a required circuit via the flexible printed cable F. The mechanical connection between the EL element E and the flexible printed cable F is made by a portion excluding the conductive path on the surface of the flexible printed cable F where the hot melt layer is formed.

Although the electrical and mechanical connection of the EL light emitting device can be obtained inexpensively by the above-mentioned joining, in the present invention, the EL light emitting device is attached to the EL element E in order to further improve the mechanical strength of the connection portion. A reinforcing sheet 13 is provided so as to cover the upper surface of the flexible printed cable and the area around the flexible printed cable.

FIG. 1 shows a reinforcing sheet 13 so as to overlap the periphery of the flexible printed cable F attached to the EL element E and a part of the flexible printed cable F.
Is attached. A double-sided adhesive tape 14 is attached to the attaching surface of the reinforcing sheet 13, and the attaching process is completed only by removing the backing paper and abutting the adhesive tape attaching surface of the reinforcing sheet 13 at a predetermined position and pressing it. Although the bonding strength between the EL element E and the flexible printed cable F is improved by sticking the reinforcing sheet 13,
The extension of the reinforcing sheet 13 is also applied to the portion of the flexible printed cable outside the outer periphery of the EL element E.
By providing 3a, the portion where the bending moment is applied by the external force applied to the flexible printed cable is reinforced, so that the strength of the boundary portion of the flexible printed cable is improved.

FIG. 3 shows an example in which the reinforcing sheet 15 is attached so that the periphery of the flexible printed cable F and the entire flexible printed cable F overlap. The strength of the entire flexible printed cable is improved in addition to the above-described joint and the boundary between the flexible printed cables.

[0019]

According to the present invention, in an EL light-emitting device in which an EL element and a flexible printed cable are electrically and mechanically connected only by applying heat and pressure in an extremely simple process, the flexible printed cable is bonded. By attaching the reinforcing sheet to the surrounding area, the connection strength between the EL element and the flexible printed cable is improved. Therefore, they do not peel off or break during installation of the EL light emitting device. In addition, if the range of attachment of the reinforcing sheet is expanded to the entire flexible printed cable, the resistance to the action of the moment due to the external force increases.

[Brief description of the drawings]

FIG. 1 shows an embodiment of the present invention, in which (a) is a partially cutaway sectional view and (b) is a rear view.

FIG. 2 shows an EL element used in the present invention, in which (a)
Is a schematic cross-sectional view, and (b) is a rear view.

FIG. 3 is a rear view showing another embodiment of the present invention.

[Explanation of symbols]

 E EL element F Flexible printed cable 1 Base film 2 Transparent electrode layer 2a Transparent electrode exposed part 3 Light emitting layer 4 Insulating layer 5 Back electrode layer 13, 15 Reinforcement sheet

Claims (1)

(57) [Claims] 1. A transparent electrode layer is formed on the back side of a base film, a portion around the transparent electrode layer is left as a transparent electrode exposed portion, and a light emitting layer is formed on a back surface of the transparent electrode layer other than the exposed portion. , the insulating layer, and the EL elements formed by the back electrode layer are sequentially stacked, the EL light-emitting device comprising a flexible printed cable is connected by thermocompression bonding one surface in contact with the back surface side of the EL device, the flexible printed Cable is made of insulating sheet
Two conductive paths are formed in parallel on one side and
A hot surface is formed on the conductive path forming surface facing the back surface of the EL element.
A melt layer and a heat-resistant resin layer are alternately formed, and the two conductive paths are exposed to the back electrode layer and the transparent electrode.
Hot melt that is in contact with the
And a reinforcing sheet covering the periphery of the flexible printed cable to be attached to the EL element is attached to the back surface of the flexible printed cable. apparatus.