JPH074793Y2 - EL element structure - Google Patents

Description

[Detailed Description of the Invention] [Industrial application] The present invention relates to an EL element used in a display device for displaying characters, numbers, symbols, patterns, etc., and in particular, it is a distributed EL device capable of double-sided display. It relates to the structure of the device.

[Prior Art] In recent years, with the demand for flatness, thinness, portability, etc. of information display media, as an EL (electroluminescence) element widely used in displays for digital wrist watches, displays for calculators, and word processors. Is roughly divided into a dispersion type EL element and a thin film type EL element, and both are classified into an AC driving type and a DC driving type depending on a voltage applied between electrodes. As shown in FIG. 3, the type EL element uses a light emitting layer 3 in which a phosphor 1 is dispersed in a binder 2 and a thickness of several tens of μm is formed by a screen printing method or the like. The insulating layer 6 is interposed between the metal electrode 5 and the like, and the whole is covered and protected by the moisture-proof seal 7. In this case, it is divided into an organic type (organic adhesive) and an enamel type (low melting point glass) depending on the material of the binder 2, and the light emitting layer 3 is practically used.
In many cases, a white reflective layer such as BaTiO ₃ is provided on the back surface side of.
In the case of the AC drive system, ZnS is used as the base material for phosphor 1 and C
A blue-green light emitting material to which u, Al, Cl, etc. are added is general. The principle of operation is that when the electric field applied to the light emitting layer 3 reaches a predetermined value, a high electric field is locally generated at the grain boundary of the phosphor 1 and the boundary with the binder 2, so that the electrons are shallow donor quasi-states in the barrier. Excited into the conduction band from the position and become photoelectrons. Then, this is accelerated by a stronger local electric field and collides with the emission center to excite secondary electrons into the conduction band, and emits light 8 when the electron falls into the empty emission center. .

In addition, the extraction electrodes 9 and 10 and the power source 11 are provided.

[Problems to be Solved by the Invention] By the way, all of the conventional dispersion type EL elements 12 are only one-sided display, and there is a demand for a double-sided display. In that case, as shown in FIG. 4, a method of disposing the light emitting layers 3 on both surfaces of the metal electrode 5 with the insulating layer 6 interposed therebetween, and as shown in FIG.
It is conceivable that the two-sided tape 13 is integrally bonded.

However, the light emitting layers 3 and 3 are formed on both sides of the former one metal electrode 5.
In the method of providing the above, not only the insulative treatment and the conductive treatment of one of the extraction electrodes 10 connected to the metal electrode 5 are troublesome, but also because of the mounting dimension D of the extraction electrode 10 to the metal electrode 5, the extraction electrode 10 side There is a problem that the dimension of the light emitting layer 3 is shortened and the light emitting areas of the front and back surfaces of the display device are different. Further, if the light emitting layer 3 is formed on one surface and then the other light emitting layer 3 is applied to the other surface, the light emitting layer 3 already attached may be damaged, and careful handling is required. It Furthermore, since the front and back sides are manufactured simultaneously, if a defect occurs on only one side, the entire dispersion type EL element 12 becomes a defective product, and there are many drawbacks such as a reduction in product yield.

On the other hand, the latter method of adhering the two dispersed EL elements 12 and 12 with the double-sided tape 13 does not meet the demand for thinning because the total thickness increases significantly, and there is a problem in the durability of the tape. Yes, and if you want to bend the distributed EL element 12 if it is thicker,
There was also a problem that it was difficult to bend.

Therefore, the present invention solves the above-mentioned problems of the related art, and realizes double-sided display with the same display area with a relatively simple structure and a slight increase in thickness.
The purpose is to provide the structure of the EL element.

[Means for Solving the Problems] In order to achieve the above-mentioned object, the present invention has two dispersion type EL devices in which a light emitting layer is interposed between a transparent electrode and a metal electrode with an insulating layer interposed therebetween. It is integrally joined with a conductive adhesive, and these dispersion type EL elements are covered and protected by a moisture-proof seal.

[Operation] In the present invention, two dispersion type EL elements, in which a light emitting layer is interposed between an insulating layer and a transparent electrode and a metal electrode, are back-to-back and integrally bonded by a conductive adhesive. Therefore, the extraction electrode can be sandwiched between these two elements at the time of this bonding.

[Embodiment] Hereinafter, the present invention will be described in detail based on an embodiment shown in the drawings.

FIG. 1 is a sectional view showing an embodiment of the structure of an EL device according to the present invention, and FIG. 2 is a plan view. The same parts as those in FIGS. 3 to 5 are designated by the same reference numerals, and the description thereof will be omitted. In these figures, the present embodiment shows a dispersion-type EL device 1 having two identical shapes before sealing, each consisting of a light emitting layer 3, a transparent electrode 4, a metal electrode 5 and an insulating layer 6.
The two electrodes 12 and 12 are back-to-back so that the metal electrodes 5 are in close contact with each other, and one of the extraction electrodes 10 is sandwiched, and they are integrally joined by a conductive adhesive 20. After being connected to the transparent electrodes 4 of 12 and 12, both dispersion type EL elements 12 and 12 are covered and protected by a transparent moistureproof seal 7. Each distributed EL element 1
2,12 are manufactured individually in advance by the same manufacturing process as before, and those that have been inspected as good products are used.

Thus, in such an EL element 21, since one extraction electrode 10 is sandwiched between the joint surfaces of two dispersion type EL elements 12 formed in the same shape, the display area of the front and back surfaces can be made the same. It is possible to prevent the non-light emitting portion from increasing due to the extraction electrode. In addition, since two good products that have been inspected are used, the defective rate as a final product is small. Further, as compared with the conventional structure shown in FIG. 4 which uses the double-sided tape, the moisture-proof seal between the bonding surfaces of the metal electrode 5 can be reduced to about half, so that the material cost can be saved and the conductive adhesive can be used. 20
Since it is completely shielded from the outside air by the moisture-proof seal 7, it is not short-circuited or deteriorated and the EL element 21 has good durability.

[Effects of the Invention] As described above, the structure of the EL element according to the present invention is such that two dispersion type EL elements are integrally joined back to back with a conductive adhesive sandwiching the extraction electrodes. Since the element is covered and protected by the moisture-proof seal, it is not affected by the extraction electrode, and therefore the same emission area on the front and back sides can be achieved without increasing the number of non-emission areas. Its practical effects are extremely large, such as the generation of non-defective products.

[Brief description of drawings]

FIG. 1 is a sectional view showing an embodiment of the structure of an EL device according to the present invention, FIG. 2 is a plan view, FIG. 3 is a sectional view showing the basic structure of a conventional distributed EL device, FIG. FIG. 5 is a cross-sectional view showing a method of making a double-sided type. 1 ... Phosphor, 2 ... Binder, 3 ... Light emitting layer, 4 ...
Transparent electrode, 5 ... Metal electrode, 6 ... Insulating layer, 7 ... Moisture-proof seal, 9,10 ... Extraction electrode, 12 ... Dispersion type EL element,
20: Conductive adhesive.

Claims (1)

[Scope of utility model registration request] 1. A dispersion type EL element having a light emitting layer interposed between a transparent electrode and a metal electrode with an insulating layer interposed therebetween is back-to-back and integrally joined by a conductive adhesive to disperse these elements. EL element structure characterized by covering and protecting the type EL element with a moisture-proof seal.