JPH0332079Y2 - - Google Patents

Description

[Detailed explanation of the idea]

[Industrial Application Field] The present invention relates to a moisture-proof structure for an electroluminescent device. [Prior art] In recent years, electroluminescent devices (hereinafter referred to as
As the materials and technology of ELDs (abbreviated as ELDs) have progressed, relatively bright ELDs have become manufactured.
Its uses are expanding. Among them, decentralized
The range of use of ELD is expanding due to its low cost and high brightness, and it is attracting a lot of attention. FIG. 2 is a cross-sectional view showing an example of a conventional ELD, in which 1 is a transparent sheet, 2 is a transparent electrode formed on the lower surface of the transparent sheet 1, and 3 is a light emitting layer made of a phosphor and a dielectric. , 4 is a counter electrode made of metal foil, 5 is a moisture absorption layer made of a material with high moisture absorption efficiency,
6 and 7 are protective sheets that hermetically cover the laminate of the transparent sheet 1, the transparent electrode 2, the light emitting layer 3, the counter electrode 4, and the moisture absorption layer 5. The transparent electrode 2 and the counter electrode 4 are each led out to the outside through lead terminals (not shown), and by applying a voltage from the outside between the transparent electrode 2 and the counter electrode 4, the light emitting layer 3 is now lit. By the way, if such an ELD is used with moisture present in the light-emitting layer 3, the phosphor will rapidly decompose, the brightness will deteriorate, and the lifespan will be significantly reduced. By tightly joining the ends of the protective sheets 6 and 7 made of plastic films by heat sealing or the like, it is possible to prevent moisture from entering the inside of the ELD. A moisture-absorbing layer 5 formed by adhering water-absorbing powder such as silica gel to a polyester film is interposed. In other words, although a considerable moisture-proofing effect can be expected from the protective sheets 6 and 7, in reality, moisture that permeates through the joints between the protective sheets 6 and 7 and the protective sheets 6 and 7 themselves cannot be ignored. From the direction of arrow A in Figure 2
Water vapor that has entered the inside of the ELD can be adsorbed by the moisture absorbing layer 5 through the gap 8. [Problems to be solved by the invention] However, the above-mentioned conventional ELD has problems because moisture-proofing measures are taken on the opposite electrode 4 side of the light emitting layer 3 by the moisture absorbing layer 5 and the opposite electrode 4 made of metal foil. However, there was a problem with the moisture-proofing measures on the transparent electrode 2 side of the light-emitting layer 3. That is, water that permeates the protective sheet 6 made of polyethylene film or the like permeates the transparent sheet 1 made of polyester film or the like that is in close contact with the protective sheet 6 and soaks into the light-emitting layer 3. I was forced to shorten my lifespan. Therefore, the moisture absorption layer 5
It is also possible to interpose a moisture absorption layer similar to that between the protective sheet 6 and the transparent sheet 1, but since materials with high moisture absorption efficiency are generally opaque, the transparency of the light-transmitting part of the ELD will deteriorate significantly. There's a problem. Therefore, it is an object of the present invention to provide a moisture-proof structure for an electroluminescent element that solves the problems of the prior art and provides a reliable moisture-proof effect without deteriorating the transparency of the light-transmitting part. There is a particular thing. [Means for solving the problem] In order to achieve the above object, the present invention provides a light-emitting layer between a transparent electrode formed on one side of a transparent sheet and a counter electrode arranged opposite to the transparent electrode. In the electroluminescent element, the transparent electrodes facing each other are hermetically covered with a protective sheet, and a hygroscopic layer made of a material with high moisture absorption efficiency is interposed between the protective sheet and the counter electrode. Fine powder was scattered between the sheet and the protective sheet, and the gap defined by the fine powder was configured to communicate with the moisture absorbing layer. [Function] That is, in the present invention, the protective sheet and the transparent sheet facing each other are not in close contact with each other, and a gap is defined between the two sheets, and this gap is communicated with the moisture absorbing layer. through the protective sheet
The moisture absorbing layer is designed to absorb water vapor that enters the ELD. [Example] Hereinafter, an example of the present invention will be described with reference to the drawings. FIG. 1 is a partial sectional view of an ELD showing an embodiment of the present invention, and parts corresponding to those in FIG. 2 are given the same reference numerals. In FIG. 1, 1 is a transparent sheet made of polyester film, 2 is a transparent electrode formed by forming a thin film of mixed oxide of In and Sn on the lower surface of the transparent sheet 1, and 3 is ZnS-Mn, ZnS-Cu, etc. 4 is a counter electrode made of aluminum foil, and 5 is a moisture absorption layer made of a polyester film to which water-absorbing powder such as silica gel is attached.
6 and 7 are protective sheets made of polyethylene film, and the ends of these protective sheets 6 and 7 are tightly bonded together by heat sealing or the like, so that the transparent sheet 1, the transparent electrode 2, the light emitting layer 3,
The counter electrode 4 and the laminate of the moisture absorption layer 5 are hermetically coated. 9 is the transparent sheet 1 and the protective sheet 6
In this example, alumina powder with a particle size of 2μ is used as the fine powder scattered between the Then, a small amount of fine powder 9 was blown onto the transparent sheet 1 using air. Reference numeral 10 denotes a gap defined between the transparent sheet 1 and the protective sheet 6 due to the presence of the fine powder 9, and this gap 10 is similar to the gap 8.
It is communicated with the moisture absorbing layer 5 via. Also,
The transparent electrode 1 and the counter electrode 4 are each led out to the outside via a lead terminal (not shown),
By applying a voltage from the outside between the transparent electrode 2 and the counter electrode 4, the light emitting layer 3 emits light. In this way, when the transparent sheet 1 and the protective sheet 6 are not in close contact with each other and a gap 10 is defined between the sheets 1 and 6, and this gap 10 is communicated with the moisture absorption layer 5, the protective sheet Since water vapor entering the ELD through the gap 6 is adsorbed by the moisture absorbing layer 5 through the gap 10 and the gap 8, the moisture-proofing effect of the light emitting layer 3 on the transparent electrode 2 side is enhanced. Moreover, the moisture-proofing means is simply a small amount of powder with a small particle size scattered, and it is visually indistinguishable from a product without powder mixed in, and there is no risk of impairing the transparency of the light-transmitting part of the ELD. . Further, the side of the counter electrode 4 of the light emitting layer 3 has a moisture-proof structure with the moisture absorbing layer 5 and the counter electrode 4 made of metal foil, as in the conventional example, so there is no fear that moisture will penetrate. In addition,
The moisture-absorbing layer 5 formed by adhering water-absorbing powder to a polyester film can be expected to have a high moisture-absorbing effect because a gap is defined between it and the protective sheet 7 due to the presence of this water-absorbing powder. can. Table 1 below shows the case where fine powder 9 is mixed between the transparent sheet 1 and the protective sheet 6 to define a gap 10 (this example), and the case where both sheets 1 and 1 are mixed with no fine powder, These are the experimental results obtained by conducting an ELD humidity test for the case where ELD 6 was brought into close contact (conventional example). Here, the experimental conditions were a temperature of 40°C and a humidity of 90°C.
~95%, 100V-50Hz, and the half-life of the luminance was measured.

[Effect of idea]

As explained above, according to the present invention, a gap is defined between the protective sheet and the transparent sheet that face each other, and this gap is communicated with the moisture absorption layer, so that the transparent electrode side of the light emitting layer is also It is possible to prevent the penetration of moisture, greatly extending the life of the electroluminescent element, and since such moisture-proofing measures only involve scattering fine powder between the protective sheet and the transparent sheet, electroluminescent elements There is no risk of deteriorating the transparency of the light-transmitting portion of the sense element.

[Brief explanation of drawings]

FIG. 1 is a partial sectional view of an ELD showing an embodiment of the present invention, and FIG. 2 is a sectional view of an ELD showing a conventional example. DESCRIPTION OF SYMBOLS 1...Transparent sheet, 2...Transparent electrode, 3...Light emitting layer, 4...Counter electrode, 5...Moisture absorption layer, 6,7...
...protective sheet, 8...gap, 9...fine powder, 1
0...Gap.

Claims (1)

[Scope of utility model registration request] A light-emitting layer is interposed between a transparent electrode formed on one side of a transparent sheet and a counter electrode disposed opposite to the transparent electrode, and the light-emitting layer is hermetically covered with a protective sheet, and the protective sheet and the counter electrode are In an electroluminescence element, a moisture absorbing layer made of a material with high moisture absorption efficiency is interposed between the two electrodes, and the light emitting layer is made to emit light by applying a voltage between the two electrodes, wherein the transparent sheet and the transparent sheet facing each other are made to emit light. 1. A moisture-proof structure for an electroluminescent element, characterized in that fine powders are interspersed with a protective sheet, and gaps defined by these fine powders are communicated with the moisture absorbing layer.