JPS6235236B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention comprises sandwiching a phosphor layer between a pair of electrodes,
An electroluminescent display element (hereinafter referred to as EL) that emits light by applying a DC voltage between both electrodes.
(referred to as a display element).

The phenomenon of emitting light when voltage is applied to a phosphor made of zinc sulfide (ZnS) or other material injected with activator or activator impurities is well known as electroluminescence (EL), and this phenomenon can be used to
EL light emitting devices have been developed. EL light-emitting elements have attracted attention in recent years as an energy-saving light source because they consume less power and generate less heat, and can be made very thin. Furthermore, with the rapid digitalization of electronic devices and the diversification of display formats, attempts have been made to put EL light-emitting elements into practical use for display purposes. However,
If moisture is present inside an EL light-emitting element, the decomposition of the phosphor such as zinc sulfide will progress and the brightness will deteriorate significantly, making it unusable as an EL display element. Therefore, when manufacturing EL display elements, sufficient care must be taken to ensure that no moisture is present inside the element.

Figure 1 shows the structure of a general EL display element. 1 is an organic transparent insulating film made of ethylene trifluoride chloride, etc.; 2 is an oxidized film of gold, aluminum or ITO (In and Sn) formed into a mesh shape; 3 is a transparent electrode that allows EL light to pass through, and is formed by vapor-depositing a substance such as a substance) on a transparent insulating film, and 3 is a transparent electrode that can transmit EL light. A phosphor layer made by dispersing phosphor powder injected with phosphor powder in an organic binder such as cyanoethylated cellulose or fluorine resin,
4 is a counter electrode made of aluminum or gold foil or plate, and 5 is a moisture-proof protective film made of a fluorochloroethylene film alone or a laminate of a trifluorochloride ethylene film and a polyethylene film. When a DC voltage is applied between the transparent electrode 2 and the counter electrode 4 of the EL display element having the above configuration, the phosphor layer 3 emits light and a display is performed.

Next, a method of manufacturing a conventional EL display element will be explained. First, a phosphor layer forming paste containing a mixture of cyanoethylated cellulose and phosphor powder is applied onto the counter electrode 4 made of metal foil or metal plate such as aluminum and dried to form the phosphor layer 3. . Further, a transparent electrode 2 formed on the transparent insulating film 1
is placed on the phosphor layer 3 and bonded under heat and pressure to produce an EL display element substrate.

Furthermore, the EL display element substrate is sandwiched between a moisture-proof protective film made of a single trifluorochloroethylene film or a laminate of a trifluorochloroethylene film and a polyethylene film, and then passed between heating rolls and adhesively sealed. stop
They were making EL display elements.

Figure 2 A and B were produced using the conventional method described above.
These are a front view and a cross-sectional side view, respectively, showing an EL display element. As shown in FIG. 2A, in the EL display element manufactured by the conventional manufacturing method, the periphery (non-display area) of the protective film 5 is
It had to be made 3 to 5 mm larger than the EL display element substrate. Also, as shown in Figure 2B,
When adhesively sealing the EL display element substrate 6 with the protective film 5, a void 7 is created near the end of the EL display element substrate 6.
is likely to occur and moisture is likely to be contained in the void 7, and the completed
This reduced the reliability of EL display elements.

FIG. 3 shows an EL display element manufactured by a conventional method in which the middle part of the display part has an opening, and numeral 8 indicates the opening. A conventional method for manufacturing this type of EL display element is as follows. First, the EL in the opening
A display element substrate is prepared, and the EL display element substrate is sandwiched between protective films and passed between heated rolls to be adhesively sealed. Next, excess portions of the protective film 5 on the outer periphery and the opening are cut off to complete the EL display element.

This type of EL display element manufactured using the conventional method is
As shown in the figure, the protective film on the outer periphery and around the opening 8 (non-display area) is 3 to 5 mm larger than the EL display element base 6 to prevent moisture, which limits the shape and limits miniaturization. It was hot. In addition, the conventional method is not suitable for continuous manufacturing and mass production because the EL display element substrate is cut or apertures are formed before moisture-proof sealing to form a complicated shape.

The present invention has been made to solve the above-mentioned drawbacks, and a phosphor-forming paste is applied and dried on a transparent insulating film on which transparent electrodes of a predetermined shape are continuously formed on the surface. a step of continuously forming a phosphor film to produce a phosphor film; a step of press-bonding a metal foil onto the phosphor layer of the phosphor film to produce a continuous phosphor film; A process of sandwiching two protective films from above and below and sealing by heat-pressing to produce a continuous EL display element base film, and a process of punching and cutting the EL display element base film into an arbitrary shape to produce an EL display element base film. and a step of sealing the periphery of the cut portion of the EL display element substrate.

Hereinafter, the present invention will be explained in more detail with reference to Examples.

Example 1 A transparent electrode made of indium oxide and tin oxide is formed on a transparent insulating film made of a polyester sheet with a thickness of 0.1 mm by sputtering or vapor deposition. Next, a vehicle was prepared by mixing cyanoethylated cellulose and a solvent such as acetone, methyl ethyl ketone, or ethyl acetoacetate at a weight ratio of 1:1 to 10, and copper and aluminum were injected into the zinc sulfide. A phosphor paste is prepared by mixing phosphor powder and cyanoethylated cellulose in a vehicle at a weight ratio of 1:1 to 10. The phosphor paste is continuously coated and dried on the transparent electrode using a roll coater method, a printing method, or a spray method so that the film thickness after drying is 10 to 50 μm to form a phosphor layer. Create a body film. The fluorescent film and a counter electrode made of aluminum foil with a thickness of 10 to 50 μm are stacked together, heated to 80 to 170°C, and pressed together by passing through a roll at a pressure of 10 to 80 kg/cm ² to create a luminescent film. do. It is preferable to use silicone rubber with a thickness of 3 to 10 mm on the back surface of the counter electrode for the roll used for crimping to prevent damage such as distortion during crimping due to surface irregularities of the phosphor layer. Next, the polyethylene sides of two hoop-shaped moisture-proof protective films that are wider than the luminescent film and laminated with trifluorochloroethylene and polyethylene are bonded together, and the luminescent film is sandwiched between them and heated to 90 to 150°C. A continuous hoop-shaped EL display element substrate film is produced by passing through a heated roll and sealing by pressure. Further, the hoop-shaped EL display element substrate film is punched out into a predetermined shape using a press or the like and cut into individual pieces to produce an EL display element substrate.

Finally, the EL display element substrate is heated to 250 to 350° C. with a hot melt gun, and liquid chlorinated trifluoride is applied to the periphery of the cut portion, followed by cooling to complete the EL display element.

4A and 4B are a front view and a cross-sectional side view, respectively, of the EL display element produced in this way,
As shown in Figure A, the peripheral area of the EL display element substrate 6 and the peripheral area of the opening 8 (non-display area) are also extremely small, and as shown in Figure B, the area near the end of the EL display element substrate 6 is also small. No voids occur. Therefore, an EL display element that can be miniaturized and has high signal quality can be manufactured. In addition, since the phosphor layer is formed by applying and drying the paste on the insulating film, there is no need to form a sheet-like phosphor layer in advance.
Since no cracks occur in the formed phosphor layer during formation of the phosphor layer, high-quality EL display elements can be manufactured with good yield.

In addition, 1 is a transparent insulating film, 2 is a transparent electrode,
3 is a phosphor layer, 4 is a counter electrode, and 5 is a protective film.

Example 2 FIG. 5 is a cross-sectional side view of an EL display element during the manufacturing process according to this example. Same as Example 1
An EL display element substrate was prepared, as shown in Figure 5.
A U-shaped sealing material 9 made of trifluorochloroethylene is sandwiched around the outer periphery of the EL display element substrate, and an opening 8 is formed.
An umbrella-shaped sealing material 10 made of ethylene trifluoride chloride is applied. Next, around the outer periphery and the opening,
The sealing materials 9 and 10 are melted and sealed using a heating iron heated to 250 to 350° C. or by blowing hot air to complete the EL display element. In this example as well, the completed
The EL display element is completely sealed around the periphery, and is small and highly reliable.

In addition, 1 is a transparent insulating film, 2 is a transparent electrode,
3 is a phosphor layer, 4 is a counter electrode, and 5 is a protective film.

Example 3 In the same manner as in Example 1, when the periphery of the EL display element substrate including the opening is heated from above and below to 250 to 350°C using a heating beam such as a laser beam or an infrared beam, the upper and lower moisture-proof protective films are heated. , it melts and flows to cover the cut surface. After that, when the heating beam is removed, the peripheral area is cooled and a strong moisture-proof film made of trifluorochloroethylene is formed.

As can be seen from the above description, in the present invention, there is no need to form a sheet-like phosphor layer in advance, and there is no need to form cracks in the phosphor layer when forming the phosphor layer. Since this does not occur, high-quality EL display elements can be manufactured with high yield. Furthermore, since the non-display area can be made extremely small, there is a greater degree of freedom in shape design, and there is no gap at the edge of the EL display element substrate, making it highly reliable.
There is a great advantage in that it can provide a display element substrate.

[Brief explanation of the drawing]

Fig. 1 is an enlarged cross-sectional side view of the main part of an EL display element, Fig. 2 A and B are a front view and an end sectional side view of a conventional EL display element, respectively, and Fig. 3 is a conventional example showing an opening. FIG. 4 is a front view of an EL display element according to an embodiment of the present invention, FIG. 4A is a front view of the EL display element, FIG. This is an example. 1...Transparent insulating film, 2...Transparent electrode, 3
... Fluorescent layer, 4 ... Counter electrode, 5 ... Protective film, 6 ... EL display element substrate, 7 ... Gap, 8
... Opening portion, 9, 10 ... Sealing material.

Claims (1)

[Claims] 1. A step of manufacturing a phosphor film by coating and drying a phosphor-forming paste on a transparent insulating film on which transparent electrodes of a predetermined shape are continuously formed on the surface to continuously form a phosphor layer; a step of press-bonding a metal foil onto the phosphor layer of the phosphor film to produce a continuous luminescent film; and 2.
A process of creating a continuous EL display element base film by inserting two protective films from above and below and sealing them by heat and pressure, and punching and cutting the EL display element base film into an arbitrary shape to produce an EL display element base. and a step of sealing the periphery of the cut portion of the EL display element substrate.
Method for manufacturing EL display elements.