JPS6276279A - Electroluminescent indicator - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to an electroluminescent (hereinafter referred to as EL) display body used outdoors.

(Prior art and its drawbacks) FIG. 2 is a sectional view showing the basic structure of the EL element.

The phosphor layer 13 is made of zinc sulfide (ZnS), a mixed crystal of ZnS and zinc selenide (ZnSe), a mixed crystal of ZnS and cadmium sulfide (CdS), etc. as a base material, and an appropriate activator is added thereto. It is formed by This phosphor layer 13
On the surface of the transparent conductive film, tin oxide (SnOz) 12
A back electrode 15 made of animinium (AI) or the like is formed on the back surface of the phosphor layer 13 with a white reflective layer 14 interposed therebetween. Furthermore, a fluororesin film is used as a protective sheet 11 to seal the entire structure, and the EL element is completed. At this time, between the transparent electrode 12 and the surface electrode 15, 50 to 1000
H2: When an alternating voltage of 50 to 100 V is applied, the phosphor layer 13 emits surface light. By using the activator, it is possible to emit surface light in any color such as green, blue, orange, yellow, etc.

However, to date, EL elements have only been used in some consumer instruments, indoor accessory lighting devices, and liquid crystal backlights.

This is because the EL element is extremely susceptible to weather resistance such as moisture and ultraviolet rays. For example, a voltage of 50 Hz and 100 V is applied to the EL element to cause it to emit surface light at a humidity of 90%. In this state, the half-life of the luminance of the EL element is 1000 hours,
It was not suitable for outdoor use.

(Object of the present invention) An object of the present invention is to eliminate the above-mentioned drawbacks and to provide an EL display whose characteristics are less likely to deteriorate due to moisture and ultraviolet rays even when used outdoors.

(Specific Means for Solving the Problems) The specific means taken by the present invention to solve the above-mentioned problems is to cover an electroluminescent element covered with an organic film using an ethylene-vinyl acetate copolymer sheet. This is because they are sandwiched and arranged on transparent substrates.

(Function) By the above-described specific means, the present invention provides an ethylene-vinyl acetate copolymer sheet that completely seals an EL element that is extremely weak in weather resistance by heating, and a blue plate glass that is an ultraviolet ray-resistant transparent substrate. By using acrylic plate and polycarbonate plate together, moisture and ultraviolet rays (wavelength 450n)
m or less), thereby effectively suppressing the deterioration of the luminance of the EL element (in the present invention, illuminance was considered), resulting in an EL display that can be used satisfactorily even outdoors.

(Example) Hereinafter, the present invention will be explained in detail based on the drawings.

Table 1 is a cross-sectional view of the EL display of the present invention.

Reference numeral 1 denotes a translucent substrate that blocks light in the ultraviolet region, and by printing arbitrary characters, symbols, etc. on the front or back surface of the translucent substrate 1, it also functions as a display substrate. The material is preferably one that blocks light in the ultraviolet region, has moisture resistance, and can also withstand a certain degree of temperature during manufacturing, such as blue plate glass, acrylic plate, and polycarbonate plate.

A first ethylene vinyl acetate copolymer sheet 2 is superimposed on the transparent substrate 1, and an EL element 3 having the above-described structure is further provided.
are arbitrarily arranged to completely cover the EL element 3 with the second ethylene vinyl acetate copolymer sheet 4, and at the same time bring it into close contact with the first ethylene vinyl acetate copolymer sheet 2 around the outer periphery of the EL element 3.

The ethylene vinyl acetate copolymer sheets 2 and 4 are brought into close contact with each other by heating and further block light in the ultraviolet region, and in this example, Dumilan (trade name), commonly known as EvA, was adopted.

Reference numeral 5 denotes a moisture-resistant sheet, which prevents, when the translucent substrate 1 equipped with the EL element 3 is attached to a frame, for example, moisture that has entered through the gap in the attachment part from getting around to the back side of the EL element and having an adverse effect. The moisture-resistant sheet 5 is made of vinyl fluoride polymer and/or aluminum foil.

This greatly improves moisture resistance.

The present inventors manufactured EL display boards with different combinations by changing the transparent substrate 1 and the ethylene vinyl acetate copolymer sheet, and examined the deterioration of the illuminance of the EL elements by irradiating them with ultraviolet rays.

Structure 1 A blue plate glass (thickness: 3.0 mm) is used as a translucent substrate 1, and first and second ethylene vinyl acetate copolymer sheets 2 are used.
, 4 was made of EVA (thickness: 0.8 mm). Among ethylene vinyl acetate copolymer sheets, EvA has particularly high moisture resistance. However, in order to tightly seal the EL element 3, it is necessary to heat it to a temperature of 160° C. or higher, which may cause a thermal shock to the protective sheet 11 of the EL element 3, so extreme caution is required. . Further, considering the same reason, blue plate glass with excellent heat resistance was used for the light-transmitting substrate 1.

EVA was superimposed on the blue plate glass, and then the EL element 3 and EVA were further superimposed. Finally, a vinyl fluoride polymer sheet (trade name: Tetra) was superimposed as a moisture-resistant sheet 5.

In this state, the temperature is raised to 160° C. while being evacuated, maintained for several minutes, and then pressurized and the entire body is heat-treated at about 155° C. for EVA crosslinking.

As a result, the EL display body 6 of the laminate is closely attached to the blue plate glass.
I got it.

Structure 2 An acrylic plate (3.0 mm thick) is used as the transparent substrate 1, and the first and second ethylene vinyl acetate copolymer sheets 2
．． Dumilan (thickness: 0.8 mm) was used for No. 4.

Dumiran is superimposed on the acrylic board, and EL element 3 is added.
and Dumilan were superimposed. Finally, a fluorinated vinyl polymer sheet was superimposed as a moisture-resistant sheet 5. In this state, heat to 110℃ while vacuuming and maintain for several tens of minutes.
Thereafter, pressure was applied to obtain an EL display body 6.

At this time, since the EL display body 6 is formed at a heating temperature of about 110°C, the adverse effects of heat on the EL element 3 are not considered at all (because the EL element 3 is molded at 120 to 130°C). There is no deformation caused by this, and an inexpensive transparent substrate made of plastic can be used.

Structure 3 Polycarbonate plate (thickness 3.0 mm) on transparent substrate 1
Dumilan (thickness: 0.8 mm) was used as the first and second ethylene vinyl acetate copolymer sheets 2.4.

Further, a vinyl fluoride polymer sheet was superimposed as a moisture-resistant sheet 5, heated under vacuum under the same conditions as Structure 2, and then pressurized to obtain an EL display 6.

Structure 4 A blue plate glass (thickness: 3.0 mm) is used as the translucent substrate 1, and the first and second ethylene vinyl acetate copolymer sheets 2
, 4 was made of Dumilan (thickness: 0.8 mm).

Further, a vinyl fluoride copolymer sheet was superimposed as a moisture-resistant sheet 5, heated under vacuum under the same conditions as Structures 2 and 3, and then pressurized to obtain an EL display 6.

The present inventors measured the initial illuminance of the EL display body 6 of structures 1 to 4 of the present invention, the illuminance after 100 hours of ultraviolet irradiation from an ultraviolet irradiation device, and the illuminance after 200 hours of irradiation. The deterioration rate was considered.

In addition, 100 hours of irradiation with an ultraviolet irradiation device is equivalent to half a year's worth of UV irradiation from natural light, and 200 hours of irradiation is equivalent to 1
Equivalent to a year's worth of UV irradiation.

As a comparative example of the EL display 6 of the present invention, an EL element with only a protective sheet shown in FIG. 2 was used.

The results are shown in the table below.

As is clear from the above table, all of the ELL displays 6 of the present invention can extremely suppress the deterioration rate due to ultraviolet rays compared to the comparative example, and especially after 200 hours, the illuminance completely exceeds that of the comparative example. I understand that. Also, no yellowing was observed in the transparent substrate 1 in terms of appearance.

Further, the present inventors exposed Structure 1 outdoors for one month, and found that the deterioration in illuminance was 2.8χ, and almost no deterioration due to moisture was observed.

In the above embodiment, a vinyl fluoride polymer sheet was used as the moisture-resistant sheet 5 superimposed on the second ethylene vinyl acetate copolymer sheet 4, but aluminum foil or a combination of these may also be used. You may.

In fact, when the ELL display of the present invention is used as an ELL display device, characters and symbols may be formed on the surface of the light-transmitting substrate 1 by printing or by a sheet having an arbitrary light-transmitting window and color filter.

(Effects of the present invention) As described above, according to the present invention, the transparent substrate - ethylene vinyl acetate copolymer sheet - EL element - ethylene vinyl acetate copolymer sheet - moisture-resistant sheet are superimposed in this order and brought into close contact. By sealing, there is no deterioration in brightness of the EL element due to moisture, and furthermore, deterioration due to ultraviolet rays of the translucent substrate and the ethylene vinyl acetate copolymer sheet can be effectively suppressed. Therefore, it becomes possible to create an EL display furnace that can be used outdoors, which has not been possible until now.

[Brief explanation of drawings]

FIG. 1 is a sectional view of an electroluminescent display body of the present invention, and FIG. 2 is a sectional view showing the basic structure of an electroluminescent element. 1... Transparent substrate 2.4. Ethylene vinyl acetate copolymer sheet 3... Electroluminescent element 5... Moisture resistant sheet

Claims (3)

[Claims] (1) An electroluminescent display comprising an electroluminescent element covered with an organic film sandwiched between ethylene vinyl acetate copolymer sheets and laminated on a transparent substrate. (2) blue plate glass in which the transparent substrate absorbs ultraviolet rays;
The electroluminescent display according to claim 1, characterized in that it is either an acrylic plate or a polycarbonate plate. (3) Claim 1, characterized in that a fluorinated vinyl polymer and/or aluminum foil is superimposed on the ethylene vinyl acetate copolymer sheet as a moisture-resistant sheet.
The electroluminescent display described in Section 1.