JP2000268979A - Electroluminescent display - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an electronic element having power saving, a long life, high performance and a low cost, by providing a dielectric insulating layer between a transparent electrode and a luminescent layer and between the luminescent layer and a back plate, and by installing a wire feeding body having a pattern like a mesh, a grid, stripes and the like on the upper surface or the lower surface of the transparent electrode. SOLUTION: A hexagonal feeding body 3 is provided on a luminescent layer 4. A transparent electrode 2 formed into a letter shape or a figure shape is provided on the feeding body 3, and a moisture-proof surface layer 1 is provided on it. A flat back plate 5 is provided on the lower surface of the luminescent layer 4 and a moisture-proof rear surface layer 6 is provided on its lower surface. There is no problem in visibility of luminescence from the luminescent layer 4, because the hexagonal feeding body 3 comprises fine wires. A clear image of a letter or a figure can be obtained. Power is supplied to the feeding body 3 from wide collectors on its end surface sides. Since the transparent electrode 2 randomly receives power from many contact positions of the feeding body 3 right under it, it is seldom influenced by the resistance of the transparent electrode 2. Uniform electroluminescence having high luminance can be materialized.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electroluminescent display (EL lamp) which uses a conductive paint excellent in migration resistance as a power supply to an electroluminescent element, consumes less power, and has a low production cost. ).

[0002]

2. Description of the Related Art An electroluminescent display is not suitable as a light source for illumination, but does not give any discomfort to human eyes because there is no sharp bright line like the emission spectrum of a fluorescent lamp. It has a very excellent feature that it can be a good surface light emitter and consumes little power. Taking advantage of these features, they have recently been used for instrument display panels and liquid crystal back panels. In addition to the above power saving and visibility,
Utilization of indoor and outdoor display devices is being studied, taking advantage of the advantage of high safety because a thick glass such as a fluorescent tube or a light bulb is not used.

[0003] However, despite having such excellent characteristics, a stable manufacturing method of an electroluminescent display has not been established, and as described later, there is no relation to the arrangement of individual figures and characters. However, the design of the display device is complicated, and the visibility of the devices of the same device varies, the power consumption is higher than expected, the lifetime is short, and the manufacturing cost is high as a whole. Was.

[0004] One of the conventional methods of designing an electroluminescent display is to incorporate an electroluminescent display over the entire surface of a display panel, that is, dispose a light-emitting layer and a transparent electrode layer over the entire surface to emit light, thereby reducing unnecessary light. A device in which light is shielded by a shield and necessary characters and figures are displayed by transmitted light has been devised. The biggest drawback of such an electroluminescent display is that power loss is large because the entire surface of the device emits light. Further, there is much waste such as disposing a transparent electrode layer, which is a relatively expensive material, on the entire surface. Furthermore, for characters such as enclosing characters and enclosing figures (for example, "mouth, country"
In the case where the shield is disconnected from the outside, the shield will fall as it is, so that it is partially connected to the outer shield (for example, a thin string-shaped shield) in order to hold the shield at that portion. Body) must be left. Such a shape is clearly unnatural and looks very bad.
In addition, there are restrictions on the design, and there is a drawback that the design is complicated in order to try to avoid such unnaturalness as much as possible.

[0005] In consideration of such a drawback, a method of directly emitting only characters and figures has been devised. In this case, of course, the light emitting layer or the transparent electrode layer itself is formed into a character or a figure, but a power supply line for supplying power thereto is provided along the outer periphery of the display pattern of the light emitting element or the transparent electrode layer. It was necessary to form a highly accurate feed line pattern that was continuous throughout. Even if a power supply line pattern is formed at one bit, the power supply line pattern needs to be adjusted to the outer periphery of the display pattern of the light emitting layer or the transparent electrode layer. Was inevitable, resulting in higher costs. Further, as described above, the power supply line pattern needs to be connected to the whole on the one hand, and on the other hand, needs to be created so that the power supply line pattern does not affect the display of the light emission pattern. As a result, the design of characters and figures is restricted, and fine displays and complicated figures cannot be arranged with continuous power supply lines between them. was there. Furthermore, even if the patterns of the power supply lines are connected as a whole, when the distance between the power supply lines increases, the electrical resistance of the transparent electrode increases, and there is a problem in that the brightness at a position away from the power supply lines decreases. For this reason, the luminance of characters and figures which should be originally the same is unbalanced, and the quality is reduced. At first glance, it seemed that the method of directly emitting light from a character or figure could solve the conventional disadvantage, but there was a problem that the size of the character or figure was restricted. From the above, at present, there is no fundamental solution even in the conventional method in which only characters and figures are directly emitted.

Further, there is a problem of the lifetime of the electroluminescent display. Generally, a conductive paint of silver particles is used as a power supply line. However, since a high voltage is applied to emit light, migration of silver occurs and a short circuit occurs between electrodes. Although this migration is affected by the presence of moisture, it is practically difficult to completely seal the electroluminescent display, so it is affected by external humidity, and the life of the electroluminescent display is particularly shortened outdoors. was there. For this reason, development of a power feeder material that does not cause migration and that can be adapted to outdoor use as an electroluminescent display has been awaited.

[0007]

According to the present invention, the design of a display device relating to the arrangement of figures and characters is simple, there is no variation in visibility among elements of the same device, the power consumption is small, and the life is short. It is an object of the present invention to obtain an electroluminescent display which is long and has improved performance as a whole and low manufacturing cost.

[0008]

The present invention provides: (1) a dielectric insulating layer provided between a transparent electrode and a light-emitting layer and / or between a light-emitting layer and a back electrode; 2. An electroluminescent display comprising a linear feeder having a pattern such as a lattice or a stripe. 2. An electroluminescent display comprising phosphor particles dispersed in a dielectric material. Luminescent display body 3 A light emitting layer in which phosphor particles are dispersed in a dielectric is provided between a transparent electrode and a back electrode, and a linear power supply having a pattern such as a mesh, a grid, or a stripe on the upper or lower surface of the transparent electrode. Electroluminescent display body characterized in that a body is installed. 4. A conductive copper powder coated with silver or nickel or a composite copper powder coated with silver on nickel. Wherein characterized in that it is a linear feeder printed sex paint 1
The present invention relates to an electroluminescent display according to any one of (1) to (3).

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 4 shows an example of a thin-film type electroluminescent display in which a dielectric insulating layer is provided between a transparent electrode and a light emitting layer and between a light emitting layer and a back electrode. In this example, a transparent electrode 15 is provided between the glass substrate 11 and the dielectric insulating layer 12, and a back electrode 16 is provided on the back of the dielectric insulating layer 13.
Is provided, and a light-emitting layer (phosphor thin film) 14 is provided between the dielectric insulating layers 12 and 13 to form an electroluminescent display. Barium titanate (BaTiO ₃ ), titanium oxide, or the like can be used as a material for the dielectric insulating layers 12 and 13. Dielectric insulating layer 12 on glass substrate 11 side
Is sufficiently thin, there is almost no obstacle to light transmission from the light emitting layer (phosphor thin film) 14. In addition, this dielectric insulating layer may be only one. The arrows in the figure indicate the direction of light emission. Although an AC power supply is connected between the electrodes, a DC power supply may be used. FIG. 5 shows an example of a dispersion-type electroluminescent display having a light-emitting layer in which phosphor particles are dispersed in a dielectric between a transparent electrode and a back electrode.
In this example, there is a light emitting layer 17 in which phosphor particles 18 are dispersed in a dielectric. Back electrode 16 and phosphor particles 18
A dielectric insulating layer 19 may be further provided between the light emitting layer 17 and the light emitting layer 17 as shown in FIG.

The above shows the basic structure of the electroluminescent display. In order to avoid the complexity of the structure, in the following description, a description (including a description of a figure) relating to a dielectric insulating layer and a dielectric such as a light emitting layer in which phosphor particles are dispersed in a dielectric and / or an insulating layer is included. Although omitted, the present invention can be applied to all the basic structures of the above-described electroluminescent display and includes these.
The feature of the electroluminescent display of the present invention is that a linear feeder having a pattern such as a mesh, a lattice, or a stripe is arranged on the upper surface or the lower surface of the transparent electrode provided on the light emitting layer, and only characters and figures are directly displayed. The point is to emit light. ,
This example is shown in FIG. 1 and FIG. In FIG. 1, a linear power supply (layer) having a pattern such as a mesh, a lattice, and a stripe, specifically, a tortoise-shaped linear power supply 3 is provided on the light emitting layer 4. A transparent electrode layer 2 in the form of characters or figures is provided on the linear feeder 3, and a surface moisture-proof layer 1 is further provided thereon.
Is provided. A flat back electrode 5 is provided on the lower surface of the light emitting layer 4, and a back moistureproof layer 6 is further provided on the lower surface. In FIG. 2, FIG.
The only difference is that the tortoise-shaped linear feeder 3 and the transparent electrode layer 2 are turned upside down, that is, the tortoise-like linear feeder 3 is disposed on the transparent electrode layer 2. Other configurations are the same as those in FIG. Since the tortoise-shaped linear feeder 3 is a thin wire, there is no problem in the visibility of light emission from the light emitting layer 4. That is, neither the configuration of FIG. 1 nor the configuration of FIG.
A clear image of characters or figures can be obtained. Note that a large upward arrow in FIGS. 1 and 2 indicates a direction in which light is emitted.

The power supply 3 is supplied with power from wide current collectors on the left and right end faces shown in FIGS. As described above, since the transparent electrode layer 2 can randomly obtain power from a large number of contact positions of the linear feeder 3 directly above or directly below, the resistance of the transparent electrode is hardly affected. As a result, uniform and high-brightness electroluminescence can be achieved. Although characters and figures can be formed in the light emitting layer, light is emitted only when power is supplied to the transparent electrode layer 2. Therefore, in order to simplify the working process, characters and figures are not formed on the light emitting layer 4. It is simpler in design to form a single layer and form characters and graphics on the transparent electrode layer 2. In addition, jumping characters, jumping figures, or delicate figures and expressions can be realized, and the degree of freedom in display body design is dramatically improved. Although FIGS. 1 and 2 show only a turtle-shape for the linear feeder 3, it can be formed in various meshes, lattices, and stripes. If a delicate character or graphic is required for the display, the mesh of the linear feeder 3 can be made finer accordingly, so that the power supply to the transparent electrode layer 2 can be adjusted freely. As described above, since the linear feeder 3 can be manufactured irrespective of the characters and figures of the transparent electrode layer 2, if the external shape and the dimensions of the mesh of the linear feeder are determined, a material formed up to the mesh of the linear feeder is formed. Can be prepared in large quantities in advance. It is advisable from the viewpoint of cost to use a conductive paint, which will be described later, as a material of the linear feeder.

As described above, the electroluminescent display of the present invention does not require the operation of preparing and printing a precise pattern of the power supply line for each character or figure of the transparent electrode, resulting in significant cost reduction. Although a transparent electrode pattern such as a mesh is required, it can be applied to various light emitting devices per se, and the cost can be hardly increased because the light emitting device can be a fixed type. Further, since power is directly supplied to the light-emitting surface, power loss is small, and a decrease in luminance at a position distant from the power supply line does not occur. Therefore, it has an excellent feature that a large-sized electroluminescence device can be manufactured.

As a material for the conductive paint, composite copper powder (Ag-Cu powder, Ni-Cu
Powder) or a composite copper powder (Ag-Ni-Cu powder) in which silver is further coated on nickel. As described above, an electroluminescent display used particularly outdoors is used under a high voltage and a high humidity, so that it is required to have migration resistance and weather resistance. It has been found that the conductive paint using the composite copper powder has remarkably improved migration resistance under high voltage and high humidity. Although the reason for this is not necessarily clear, in a conventional silver power supply line, charges are uniformly received by all silver particles in the coating film, and silver ionization and silver ion migration from the silver particle surface occur. In contrast, composite copper powder coated with silver or nickel (Ag-Cu powder, N
In the case of i-Cu powder), since the charge is supported by the entire composite particle system, there is a gap of an atomic order between the particles, and silver,
It is considered that the electric characteristics of nickel and copper are different from each other, so that the driving force of ionization of silver on the silver surface and movement of silver ion in the coating film, which induces migration, is suppressed as compared with silver particles. In particular, in the case of a composite copper powder (Ni-Cu powder) coated with nickel, since oxidation of copper is suppressed by a nickel film and nickel itself has a good migration resistance, it has a low cost and a long life. A luminescence display can be realized. However, although the conductivity is inferior to silver-coated composite copper powder, the use of silver-coated copper powder is rather important for use in large and inexpensive electroluminescent displays that can use a wide power supply line for outdoor applications where the demand for migration resistance is severe. It can be said that it is more suitable than composite copper powder. Further, composite copper powder (Ag-Ni-Cu powder) in which silver is further coated on nickel has both the conductivity of silver and the anti-migration property of nickel, and is therefore more suitable.

A conductive paste is prepared using these conductive metal composite powders. In this case, an organic binder such as an epoxy resin, a phenol resin, an unsaturated polyester resin, a saturated polyester resin, a polyamide resin, a polyimide resin, a polyamideimide resin, an acrylic resin, or an inorganic binder such as a glass frit is used as the binder. If necessary, a curing accelerator and a solvent may be added. Typical curing accelerators such as imidazole and amines, and solvents such as butyl cellosolve, terpineol,
Examples include ethylene carbitol and carbitol acetate. The conductive paste is obtained by appropriately adding and mixing these. The content of the binder is preferably 5 to 30% based on the conductive paste.

The electroluminescent display of the present invention can be used for various display panels, figures and designs. For example, it can be used indoors for information boards, emergency lights, warning boards, bulletin boards, etc., and outdoors for company names, store names, display boards / towers, advertising boards / towers, various traffic signs, and display of construction sites. Of course, it can be used for the display panel of various instruments and the back panel of liquid crystal. Since the electroluminescent display of the present invention can be made very thin as described above, it is much easier to install than a conventional display or a device containing a fluorescent tube, a light bulb or a neon tube. And it can be easily mounted on indoor walls.
Further, since glass is not used, there is an advantage that the safety is high, the assembling or supporting device of the display body is simple, the time required for the construction is reduced, and the cost is reduced. And, as described above, light emission by electroluminescence is visually recognized as very gentle light, so it is particularly used for various display devices such as guide lights and display boards in hospitals, movie theaters, night buildings, railway and subway premises. It is suitable. In addition, for advertisements and advertisements, conventional means such as neon signs of excessively stimulating and high energy consumption are not always effective, and advertisements and advertisements with a calm atmosphere of the display device of the present invention will be developed in the future. It is expected to grow. Fluorescent tubes, light bulbs, or neon tubes are themselves heating elements that dissipate considerable heat, and thus have the problem of accumulating heat when used in buildings or tunnels. In addition, only areas where neon signs and lights for advertisements are used have a brightness higher than expected, causing a loss of light / dark balance and causing discomfort. Since the electroluminescent display of the present invention does not have unpleasant glare, illumination or heat dissipation, these problems can be solved at once.

[0016]

Examples and Comparative Examples Examples of the present invention are shown below. Example 1 of an electroluminescent display (EL lamp) having a width of 300 mm and a length of 400 mm according to the present invention
Power line pattern (power line width, shape and size), type of power line printed surface (light emitting layer or transparent electrode layer), type of conductive paint (Ag-Cu powder, Ni-Cu)
Powder, Ag-Ni-Cu powder), display form (characters, figures)
Table 1 shows the results of the evaluations. Example 1
In each case of 4, the entire display section had uniform luminance, and the pattern of the power supply line did not disturb the display, and a good electroluminescent display was obtained.

[0017]

[Table 1]

Next, the manufacturing cost, the power consumption, the easiness of design of characters and figures, and the easiness of construction are compared between the embodiment of the present invention and the comparative example of the prior art. As an example of the present invention, Example 2 shown in Table 1 is given as a representative example. Further, as a comparative example of the prior art, there is a method (a) in which electroluminescence of full-surface light emission is shielded and only characters and figures are displayed as transmitted light passing through a light-transmitting body (hereinafter, referred to as a method).
It is referred to as a “transmission light display method”. ) And (b) a method in which the power supply line for supplying power is formed along the outer periphery of the display pattern of the light emitting element or the transparent electrode layer to form a continuous power supply line pattern (hereinafter referred to as a “specific power supply line method”). )). The cost and the power consumption are indicated by an index with the present invention as 100. Table 2 shows the results.

[0019]

[Table 2]

As is clear from Table 2, the present invention can greatly reduce the manufacturing cost and the power consumption.
In the present invention, for example, as shown in the shape of a turtle shell, the power supply line is fine and arranged in a large number of patterns, so that display of characters and figures is not disturbed, and characters and figures in enclaves away from the whole are not affected. Can also be supplied easily. For this reason, the degree of freedom in designing characters and figures is extremely high. On the other hand, in the conventional (b) “specific power supply line method”, it is impossible to express characters such as “river”, “ぱ”, and “ba” as they are. Also, in the conventional (a) “transmitted light display method”, an enclosed character or an enclosed figure (for example, “mouth,
In the case of a character such as "country", the shield will be disconnected from the outside, and the shield will fall as it is. Therefore, it is necessary to leave a part of the outer shield (for example, a thin shield). Although such characters are still simple, they still look unnatural and significantly reduce visibility.

In this way. According to the present invention, not only the production cost and the power consumption can be remarkably reduced, but also an electroluminescence display having a very high degree of freedom in designing characters and figures can be obtained. In the prior art (a) “transmitted light display method” or (b) “specific power supply line method”, since the power supply line is disposed at the end of the light emitting layer or around or at the end of a figure or character, The distance at which the luminance does not decrease due to the resistance of the transparent electrode has been the limit of the dimensions of the electroluminescent display and the dimensions of figures and the like therein. However, in the present invention, since the transparent electrodes can be arranged irrespective of the size of the transparent electrodes, there is no concern about a decrease in luminance due to the resistance of the transparent electrodes, and a large-sized electroluminescent display can be manufactured.

Next, the migration resistance of the embodiment of the present invention and the comparative example of the prior art will be compared. On a 100 mm × 100 mm light-emitting layer coated on an aluminum back electrode, a line width of 0.3 mm and a pattern diameter of 10 mm
The size of the feeding line of the turtle shell mesh was printed by silk printing, and a transparent electrode was printed on the entire surface of the feeding line of the mesh. Further, both the transparent electrode side and the back electrode side were covered with a moisture-proof film as shown in FIG. 1 to form a package, thereby producing an electroluminescent display. The thus produced electroluminescent display was subjected to a humidity of 95% and a temperature of 45 °.
Under the environment of C, an acceleration test was performed by applying a voltage of 200 V between the back electrode and the transparent electrode, and the time during which migration occurred was determined. The result is shown in FIG.

As is apparent from FIG. 3, migration occurs in 50 hours in the conventional conductive paint using silver particles (reference numeral 7). In contrast, the Ag of the present invention
In the conductive paint using the -Cu composite powder, migration occurred in about 1500 hours (reference numeral 8), and the migration resistance was greatly improved. Ag-N
The conductive paint using the i-Cu composite powder has about 30% more improved migration resistance than the Ag-Cu composite powder (reference numeral 9). Further, with the conductive paint using the Ni-Cu composite powder, no migration was observed even after 2500 hours (reference numeral 10). As described above, the use of the conductive paint composed of the composite copper powder coated with silver or nickel of the present invention or the composite copper powder further coated with silver on nickel as the power supply line greatly improves migration resistance. As a result, the life of the electroluminescent display is drastically extended. It should be noted that some of the materials and methods described in the above embodiments are merely examples, and various changes can be made without departing from the gist of the present invention. All of these changes are included in the present invention.

[0024]

The transparent electrode layer in the electroluminescent display of the present invention randomly obtains electric power from a large number of contact positions of the linear feeder directly above or below the transparent electrode layer, and thus is hardly affected by the resistance of the transparent electrode. In addition, jumping characters, jumping figures, or delicate figures and expressions can be realized, and the degree of freedom in display design can be dramatically improved. Further, the electroluminescent display of the present invention does not require the operation of preparing and printing a precise pattern of the power supply line for each character or figure of the transparent electrode, and thus greatly reduces the cost. In addition, since power is directly supplied to the light emitting surface, power loss is small, and luminance does not decrease at a position distant from the power supply line. Therefore, it has an excellent feature that a large-sized electroluminescent display can be manufactured. And by using a conductive paint made of a composite copper powder coated with silver or nickel of the present invention or a composite copper powder further coated with silver on nickel as a feeder line, migration resistance is greatly improved, The life of the electroluminescent display is dramatically extended. As described above, it has an extremely excellent effect as compared with the conventional electroluminescent display.

[Brief description of the drawings]

FIG. 1 is a schematic explanatory view of an electroluminescent display of the present invention in which a power supply line pattern is formed on a light emitting layer.

FIG. 2 is a schematic explanatory view of an electroluminescent display according to the present invention in which a power supply line pattern is formed on a transparent electrode layer.

Fig. 3 Results of migration resistance evaluation test

FIG. 4 is an explanatory cross-sectional view of a thin film type electroluminescent display.

FIG. 5 is an explanatory cross-sectional view of a dispersion type electroluminescent display.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Surface moisture-proof layer 2, 15 Transparent electrode (layer) 3 Power supply (line) 4, 14, 17 Light-emitting layer (phosphor thin film) 5, 16 Back electrode (layer) 6 Back surface moisture-proof layer 7 Conductivity using Ag particles Example of paint (conventional product) 8 Example of conductive paint using Ag-Cu composite powder (product of the present invention) 9 Example of conductive paint using Ag-Ni-Cu composite powder (product of the present invention) 10 Ni- Example of conductive paint using Cu composite powder (product of the present invention) 11 Glass substrate 12, 13 Dielectric insulating layer 18 Phosphor particles 19 Dielectric insulating layer

Continued on the front page (71) Applicant 397070901 Mami Kaneko Hokkaido, 11-11, Shinonome-cho, Hakodate-shi, Hokkaido (71) Applicant 397069374 Yokoyama Politics 13-17, Otemachi, Hakodate-shi, Hokkaido (71) Applicant 397069514 Koshin Electric Industry Co., Ltd. 4-7-5 Showa, Hakodate City (71) Applicant 000173511 Technopolis Hakodate Technology Promotion Association 379 Kikyocho, Hakodate-shi, Hokkaido (72) Inventor Shinichi Kawashima 32-6, Kamedahoncho, Hakodate-shi, Hokkaido (72) Inventor Hitoshi Kurokawa 2024-2, Takamatsucho, Hakodate-shi, Hokkaido 607 (72) Inventor Kanda Shuhei 8-3, Higashikawacho, Hakodate-shi, Hokkaido (72) Inventor Mami Kaneko 11-13, Shinonomecho, Hakodate-shi, Hokkaido (72) Inventor Yokoyama Politics 13-17 Otemachi, Hakodate City, Hokkaido (72) Inventor Toshio Takahashi 4-7-5 Showa, Hakodate City, Hokkaido (72) Inventor Hisashi Kaga 3-1-8 Kitamihara, Hakodate City, Hokkaido (72) Inventor Tomoaki Sugawara 3-23-13 Kamiyama, Hakodate, Hokkaido (72) Inventor Takanori Kobayashi Hakodate, Hokkaido 2-16-3 Mihara F term (reference) 3K007 AB00 AB05 AB17 AB18 CA01 CB01 CC05 DA04 DA05 EC01 5G307 AA02 FA01 FB02 FC02 FC04 FC07

Claims (4)

[Claims] 1. A dielectric insulating layer is provided between a transparent electrode and a light emitting layer and / or between a light emitting layer and a back electrode, and a pattern such as a mesh, a lattice, or a stripe is provided on an upper surface or a lower surface of the transparent electrode. An electroluminescent display comprising a linear power supply. 2. The electroluminescent display according to claim 1, wherein the electroluminescent display is a light emitting layer in which phosphor particles are dispersed in a dielectric. 3. A light emitting layer in which phosphor particles are dispersed in a dielectric material is provided between a transparent electrode and a back electrode, and a linear, grid, or stripe pattern is formed on the upper or lower surface of the transparent electrode. An electroluminescent display, comprising a power supply. 4. A linear power feeder in which a conductive paint made of a composite copper powder coated with silver or nickel or a composite copper powder further coated with silver on nickel is printed. 4. The electroluminescent display according to 3.