JP2545694B2 - Method for manufacturing dispersed EL panel - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a dispersion type EL panel used as an information display panel.

[0002]

2. Description of the Related Art An EL panel is disclosed in JP-A-60-21.
No. 6498 and the like are known.

A conventional dispersion type EL (electroluminescence) panel will be described with reference to FIG.

In FIG. 6, in a dispersion type EL panel, an insulating layer 2 and a light emitting layer 3 are sequentially formed on a back surface electrode 1 made of an aluminum foil, and a transparent front surface electrode 4 is superposed thereon, and then both surfaces are formed. Has a structure in which the outer packaging films 5a and 5b are wrapped.

In FIG. 6, the light emitting layer 3 has a structure in which phosphor particles 7 and a filler 8 are dispersed in an organic binder 6 having a high dielectric constant.

In order to sequentially form the insulating layer 2 and the light emitting layer 3 on the back electrode 1 made of aluminum foil, first, an organic binder having a high dielectric constant, such as cyanoethyl cellulose, vinylidene fluoride, is used as the insulating layer coating material. Barium titanate (BaTiO ₃ ), lead titanate (PbTiO ₃ ), titanium dioxide (TiO ₂ ) having high dielectric constant in a copolymer of vinylidene fluoride and propylene hexafluoride, etc.
In addition to being used by mixing and dispersing fine powder such as
As the light emitting layer coating material, zinc sulfide (ZnS) and copper, in an organic binder similar to that for the insulating layer coating material having a high dielectric constant,
Aluminium foil to be used as the back electrode by using these paints, which are mixed and dispersed with phosphor particles to which a trace amount of aluminum, silver, manganese, beryllium, etc. are added, and if necessary, fillers such as barium titanate. The insulating layer 2 and the light emitting layer 3 are sequentially formed on the above by a screen printing method or the like.

By the way, in order to obtain the phosphor particles 7, the following method has been conventionally used. That is, ammonium sulfide is allowed to act on a solution of a zinc salt such as zinc chloride (ZnCl ₂ ), and ZnS is first obtained as an amorphous precipitate.

Next, the ZnS obtained as the above precipitate is dried and then pulverized, and the pulverized ZnS phosphor particles are treated with an aqueous solution of nitrate, sulfate, acetate or the like of copper, aluminum, silver, manganese, beryllium or the like. Alkaline solution of hydroxide, K
Immerse in a solution containing a dopant such as a CN aqueous solution. At this time, ZnS particles aggregate, so after washing with water and drying,
The particles are pulverized again to obtain phosphor particles 7.

[0009]

However, the size of the phosphor particles 7 obtained through the crushing process as described above is as large as several .mu.m to several tens of .mu.m, and they are irregular and have various shapes. This also applies to the ferroelectric particles 10 contained in the insulating layer.

For this reason, in the dispersion type EL panel in which the phosphor particles and the like obtained as described above are dispersed, the surface roughness of the light emitting layer 3 and the insulating layer 2 prevents the incident light from the outside. There is a problem that the display light from the panel surface is difficult to read due to the phenomenon of so-called washout, which is strongly diffused and reflected.

That is, when light is incident on an ideally flat surface, only specular reflection light is generated, but when the surface is rough, considerable diffuse reflection light is generated as shown in FIG. The washout phenomenon occurs.

The light that has entered the inside of the light emitting layer 3 and the insulating layer 2 is reflected by the Al foil forming the back electrode 1 having a high reflectance, and the reflected light is again reflected by the phosphor particles 7 described above.
The light is diffusely reflected by the dispersed light emitting layer and the like, and further causes washout.

In view of the above problems, it is an object of the present invention to provide a method of manufacturing a dispersion type EL panel in which washout is prevented by reducing the diffuse reflection light and the display light of the panel is easy to read. And

[0014]

In order to achieve the above-mentioned object, the invention according to claim 1 synthesizes phosphor fine particles in a vapor phase by using a metal organic chemical vapor deposition method, and further, the phosphor fine particles are synthesized. In the vapor phase of the emission center substance, dispersing the phosphor fine particles doped with the emission center substance in the first organic binder, and adding the first organic binder to the first conductive layer. A step of applying to the film, a step of synthesizing dielectric fine particles by a chemical vapor deposition method, a step of dispersing the dielectric fine particles in a second organic binder, and a step of dispersing the second organic binder in a second conductive layer. And a step of applying to the film.

Further, the invention of claim 2 is characterized in that, in the invention of claim 1, at the same time as the synthesis of the fluorescent fine particles, the emission center substance is doped into the fluorescent fine particles.

Further, in the invention of claim 3, in the invention of claim 1, the film thickness of the first organic binder is set to about half the diameter of the phosphor fine particles, and The phosphor fine particles are dispersed in

[0017]

In the invention of claim 1, since the phosphor particles are synthesized and the emission center substance is doped into the phosphor particles in the gas phase, the formed phosphor ultra-fine particles have a uniform particle size. As a result, since the dielectric fine particles are similarly synthesized in the gas phase, the formed ultrafine dielectric particles are spherical particles having a uniform particle size and no aggregation. Therefore, the diffused reflected light can be reduced.

According to the second aspect of the present invention, at the same time that the phosphor fine particles are synthesized, the emission center substance is uniformly doped in the phosphor fine particles by doping the emission center substance into the phosphor fine particles. And the efficiency of light emission is improved.

According to the third aspect of the present invention, the first organic binder is formed to have a thickness of about half the diameter of the fine phosphor particles, so that the fine phosphor particles are contained in the first organic binder. Since it is a flat light emitting layer in which only layers are densely arranged,
It is possible to reduce diffusely reflected light due to diffused reflection between the phosphor particles.

[0020]

Embodiments of the present invention will now be described with reference to the drawings.

FIG. 1 is a cross-sectional view of a dispersion type EL panel obtained by the method of this embodiment, in which a transparent film 17b provided in the central portion and a transparent conductive film provided on both sides of the transparent film 17b. A pair of light emitting layers 15a and 15b are provided via 19b and 19c, and insulating layers 16a and 16b are further provided on the front surface side and the back surface side of the light emitting layers 15a and 15b. Reference numerals 17a and 17c denote translucent films provided on the front surface side and the back surface side of the insulating layers 16a and 16b via transparent conductive films 19a and 19d. The translucent films 17a and 17c further include the outer packaging film 18a, It is configured to be covered with 18b. The transparent conductive films 19a, 19b, 19c, 19d
A thin metal wire 20 is adhered to each of them.

FIG. 2 is an enlarged detailed view of the portion A of FIG. 1, in which the light emitting layer 15a has a high dielectric constant organic binder resin 22.
Insulation is formed by dispersing and mixing spherical phosphor ultrafine particles 21 having a particle diameter of 1 μm or less therein, and spherical dielectric ultrafine particles 23 are also dispersed and mixed in the organic binder 24 thereon. A layer 16a is provided.

Dispersion type EL obtained by the method of this embodiment
The sectional structure of the panel can be equivalently regarded as shown in FIG. That is, it is composed of a light emitting layer 15 in which spherical phosphor ultrafine particles 15A are dispersed and mixed in an organic binder 15B having a high dielectric constant, a flat insulating layer 16, and similarly flat envelope films 18, 18.

Reflected components when light is incident on the panel having the above structure from the outside are specularly reflected light, diffusely reflected light and retroreflected light as shown in FIG.

Here, the spherical phosphor ultrafine particles 15A are used.
However, the closer it is to the ideal sphere, the more the retroreflective component increases, and the diffusely reflected light decreases accordingly. Therefore, in this embodiment, the diffused reflected light is reduced by bringing the phosphor ultrafine particles 15A closer to an ideal spherical particle.

Dispersion type EL obtained by the method of this embodiment
The panel is constructed as described above. Next, a method for manufacturing the panel will be described.

First, zinc sulfide (Z
nS) with a small amount of manganese (Mn) etc. added (doping)
The spherical ultrafine particles having a diameter of 1 μm or less are used. For example, ZnS; Mn particles (ZnS doped with Mn) are prepared by using dimethylzinc (Zn (CH ₃ ) ₂ ) and hydrogen sulfide (H ₂ S) as raw materials. It is formed by the MO / CVD method (metalorganic chemical vapor deposition method). The size of the ultrafine particles obtained by this method can be controlled by the pressure in the reaction chamber, the gas flow rate, the temperature, etc.
Ultrafine particles of ZnS of m or less can be obtained.

Mn, which is a dopant, is made of tricarbonylpentadiene manganese (TCM) or the like as a raw material, and is introduced into the reaction chamber after being subjected to a cracking treatment by light or thermal plasma, and simultaneously at the process of forming the ZnS ultrafine particles. Doping in gas phase.

Other phosphor ultrafine particles ZnS; Tb, F particles and the like can also be obtained by doping Znb ultrafine particles with Tb and F in the gas phase. That is, T in the reaction chamber
By evaporating bF ₃ by resistance wire heating, T
b and F can be doped into ZnS ultrafine particles.

Next, as the dielectric ultrafine particles, TiO ₂ particles having a high dielectric constant are used. The TiO ₂ particles are titanium tetrachloride (TiCl ₄ ) and oxygen or C as a raw material.
VD (Chemical Vapor Deposition) method is used, and spherical fine particles having a diameter of 0.3 μm and no aggregation are obtained by controlling pressure and the like, as in the case of obtaining the above-mentioned phosphor ultrafine particles. .

Further, the phosphor ultrafine particles and the dielectric ultrafine particles obtained as described above are mixed with a fluorine-based resin such as polyvinylidene fluoride, which is an organic binder having a high dielectric constant, and further mixed with a suitable solvent such as dimethyl. Adjust the viscosity with acetamide or the like.

Next, In ₂ is formed on both sides of a transparent film having a relatively high heat resistance made of a polyester film or the like.
While forming a transparent conductive film such as an O ₃ thin film,
_{The 2} O ₃ thin film is etched into an appropriate pattern.

Then, to the translucent film having the transparent conductive film formed on both sides thereof, a mucus in which the ultrafine phosphor particles are dispersed in the organic binder is applied by a dipping method,
Dry with an infrared lamp. A suitable drying temperature at this time is around 80 ° C. In this case, the film thickness that can be formed in one dip can be adjusted by adjusting the amount of the solvent mixed in the organic binder, but the film thickness is about half the diameter of the phosphor ultrafine particles to be mixed. When the organic binder layer is obtained, it is possible to form a light emitting layer in which only one ultrafine phosphor particle is densely arranged as shown in FIG.

Further, the above-mentioned organic binder is similarly coated with a mucus in which ultrafine dielectric particles are dispersed by a dipping method and dried to form an insulating layer. In this case, the viscosity can be adjusted by the solvent in the same manner as in the case of forming the light emitting layer described above, but since the light emitting layer formed earlier may be dissolved by the dipping of the latter, both organic binders may be dissolved. It is effective to change the type of solvent or the type of solvent. For example, polyvinylidene fluoride is used as the organic binder for dispersing the phosphor ultrafine particles to be dipping first, dimethylacetamide is used as the solvent, and tetrafluoroethylene and polyfluoride are used as the organic binder to disperse the dielectric ultrafine particles to be dipping later. There is an example of using a vinylidene copolymer and ethyl acetate as a solvent.

In this way, the dielectric ultrafine particles can be densely arranged to form an insulating layer having a flat surface.

The light emitting layer and the insulating layer can be formed by a method such as a spray method other than the dipping method. However, when the light emitting layer and the insulating layer are formed on both sides of the film as in this embodiment, The dipping method is convenient.

Next, a translucent film with a transparent conductive film is adhered from both sides with silicon rubber or the like, and thermocompression-bonded with a roll.

Finally, the outer packaging film is laminated and completed.

In this embodiment, a thin metal wire having a diameter of about 0.1 mm is adhered on the transparent conductive film to reduce the unevenness of light emission luminance due to the resistance of the transparent conductive film.

Further, in this embodiment, when the phosphor ultrafine particles are dispersed and mixed in the organic binder, only one layer is dispersed and arranged in parallel, so that a flat light emitting layer is obtained, and the phosphor particles are diffused due to diffused reflection or the like. The amount of reflected light is reduced.

As described above, the dispersion type EL panel obtained in this example has a light emitting layer formed by dispersing spherical phosphor ultrafine particles in an organic binder having a high dielectric constant, a flat insulating layer, and the same flat layer. Since the phosphor superfine particles are spherical, the retroreflective component is increased and the diffuse reflected light is reduced by that amount when the light enters from the outside.

As a result, in the present embodiment, the diffuse reflectance of the dispersion type EL panel can be suppressed to one third or less of the conventional one, and the display light of the panel can be easily read.

Next, the dispersion type EL obtained in this example
FIG. 5 shows a comparison of the contrast expressed by the following equation between the panel and the conventional dispersion type EL panel. Contrast = (display part brightness−non-display part brightness) / display part brightness This is the brightness difference between the display part and the non-display part of the panel when the light is emitted, and the above value ( The larger the contrast, the higher the visibility. For example, when the illuminance of external light is 1000 lx, the conventional example has a contrast of 0.13 and the brightness difference is small and almost invisible, whereas the present example shows a high visibility of 0.61.

The structure of the present invention is not limited to the above-mentioned embodiment. For example, a resin substrate may be used instead of the translucent film 17b, or a light emitting layer or an insulating layer may be provided on one side of the translucent film or resin substrate. It is also possible to provide only on one side to form a single-sided light emitting panel.

The dielectric particles constituting the insulating layer are TiO 2.
₂ Not limited to ultrafine particles, but Al ₂ O ₃ and PbPT
It may be dielectric particles such as iO ₃ .

Further, the thin metal wire is not necessary for a small-scale display panel.

Further, the fluorine-based resin used as the organic binder may be another resin having high moisture resistance, such as a silicone resin or a polyurethane resin.

The insulating layer may be provided below the light emitting layer.

By subjecting the dielectric ultrafine particles forming the insulating layer to the same spherical treatment as the phosphor ultrafine particles, the diffuse reflected light can be further reduced.

[0050]

As described above, the present invention has the following effects.

(1) Since the phosphor particles are synthesized and the emission center substance is doped into the phosphor particles in the gas phase, the formed phosphor ultra-fine particles have a uniform particle size and do not aggregate. The particles become spherical particles, and since the dielectric particles are similarly synthesized in the vapor phase, the formed ultrafine particles of the particles become spherical particles having a uniform particle size and no aggregation.
Therefore, it is possible to reduce the diffusely reflected light (the effect of the invention of claim 1).

(2) At the same time when the phosphor fine particles are synthesized, the emission center substance is uniformly contained in the phosphor fine particles by doping the phosphor fine particles with the emission center substance. Therefore, the efficiency of light emission is improved (the effect of the invention of claim 2).

(3) By forming the first organic binder to have a thickness of about half the diameter of the phosphor fine particles, one layer of the phosphor fine particles are densely arranged in the first organic binder. Since it becomes a flat light emitting layer, it is possible to reduce diffuse reflection light due to diffused reflection between the fluorescent fine particles (effect of the invention of claim 3).

[Brief description of drawings]

FIG. 1 is a cross-sectional view of a dispersion type EL panel obtained by a method of an example to which the present invention is applied.

FIG. 2 is a partial detailed view of FIG.

FIG. 3 is an equivalent sectional view of the dispersion type EL panel shown in FIG.

FIG. 4 is an explanatory diagram of incident light in a dispersion type EL panel obtained by a method according to an embodiment of the present invention.

FIG. 5 is a contrast comparison diagram of a dispersion type EL panel obtained by an embodiment method to which the present invention is applied and a conventional example.

FIG. 6 is a sectional view of a dispersion type EL panel in a conventional example.

FIG. 7 is an explanatory diagram of incident light in a conventional example.

[Explanation of symbols]

 15a, 15b Light emitting layer 16a, 16b Insulating layer 17a, 17b, 17c Translucent film 21 Phosphor ultrafine particle 22 Organic binder 23 Dielectric ultrafine particle 24 Organic binder

Claims (3)

(57) [Claims] 1. Phosphor fine particles are formed by a metal organic chemical vapor deposition method.
A step of synthesizing the phosphor particles in the gas phase and doping the phosphor fine particles with the emission center substance in the gas phase;
In an organic binder, a step of applying the first organic binder to a first conductive film, a step of synthesizing dielectric fine particles by a chemical vapor deposition method, and a step of forming the dielectric fine particles in a second And a step of applying the second organic binder to the second conductive film, the method of manufacturing a dispersion-type EL panel, comprising: 2. The method of manufacturing a dispersion type EL panel according to claim 1, wherein the emission center substance is doped into the phosphor fine particles at the same time as the synthesis of the phosphor fine particles. 3. The film thickness of the first organic binder is set to about half the diameter of the phosphor fine particles, and the phosphor fine particles are dispersed in the first organic binder. 1. The method for manufacturing the dispersion type EL panel according to 1.