JP2002208490A - Laminated el element display device, and manufacturing method of the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an EL element display device at a low cost, which is made to have high light emitting efficiency for visual sensation by forming a light emission surface with one or both surfaces which faces the direction of sight line. SOLUTION: The EL element display device comprises a substrate, the first electrode formed on the substrate, a light emitting layer made of electroluminescent material, formed at least on a part of the substrate. The second electrode facing the light emitting layer, formed in a state which is not conductive with the first electrode, and the substrate and at least one side of the first electrode or the second electrode are formed by light transmitting material. Further, an insulation layer, separating the light emitting layer and the second electrode, and insulating the first electrode from the second electrode, is formed. Here, by forming both of the substrate and the first electrode, and the second electrode and the insulation layer, with light transmitting material, the light emissions on both surface of the light emission layer are made visible.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a voltage-excitation type EL (Electronic Luminescence) element that emits light (electroluminescence) by colliding accelerated electrons with the center of a phosphor in an electric field, and is used for a cellular phone or a wristwatch. The present invention relates to a stacked EL element display device for use as a light source for a backlight of a liquid crystal display, an ornament for emitting and displaying a decorative pattern or the like, and a manufacturing method thereof.

[0002]

2. Description of the Related Art Conventionally, this type of EL element has been
In this structure, the nS phosphor is overlapped and sandwiched between a light-transmitting glass electrode and a metal foil, and emits light by applying an electric field of about 10 ⁴ (V / cm). In such light emission, Zn
When a small amount of Mn is added to S (zinc sulfide), a yellow-orange light is emitted, and when a small amount of Tb is added to ZnS, a green light is emitted. In recent years, a phosphor using an organic substance instead of an inorganic substance has been developed.

[0003] In the EL element, in a structure in which it is overlapped and sandwiched in a plane, light emission from a cross section cannot be obtained.
For this reason, a light transmissive material such as indium tin oxide (hereinafter, referred to as “ITO”) is used as the sandwiching electrode. This IT0 material is in the form of a paste that is easy to handle at about room temperature, and is used as a sheet-like light-transmitting electrode material formed over a wide area by a vapor deposition technique on a sheet material such as polyethylene terephthalate (PT).

In such an EL element, when an EL layer is formed on a light transmitting electrode material, an electrode is formed on the other EL layer surface, and a voltage is applied to the EL layer, whereby uniform light emission from the light transmitting electrode material side is obtained. Is obtained. This light emission is used as a light source for a backlight of a liquid crystal display of a mobile phone or a wristwatch. Further, such an EL element is arranged, for example, so as to have a desired pattern, and an ITO electrode (cathode) is provided.
When a predetermined voltage is applied between the electrode and another electrode (anode) on the EL layer, a desired pattern is emitted and displayed.

FIG. 5 is a sectional view showing the structure of a conventional EL element, and FIG. 6 is an external perspective view for explaining a manufacturing process of the conventional EL element. FIG. 7 is a flowchart in a manufacturing process of the EL element shown in FIG.

The cross-sectional view shown in FIG. 5 shows a cross-sectional structure taken along the line BB in FIG.

In FIGS. 5, 6 and 7, first, an ITO film 2 serving as a light transmitting electrode is deposited on substantially the entire surface of one of the light transmitting substrates (PET) 1 (FIG. 6A). next,
The EL layer 3 is formed at a plurality of predetermined positions on the ITO film 2 (in the case of a backlight light source, a plurality of positions where the illumination is effectively performed). This formation is performed by application of screen printing. This application is performed so that a predetermined thickness is obtained.
For example, it is performed a plurality of times (FIG. 6B).

Further, a plurality of insulating films 4 are applied by screen printing to a predetermined thickness so as to cover each of the plurality of EL layers 3. For example, the application is performed a plurality of times (FIG. 6C). Thereafter, a resist (not shown) having a substantially similar thickness is applied around the plurality of insulating films 4 by screen printing. This application is performed a plurality of times, for example, so as to obtain a predetermined thickness.

Then, a back electrode 5 using a carbon paste or a silver paste is applied by screen printing to substantially the entire surface of the substrate (PET) 1 so as to be in contact with each of the plurality of insulating films 4 (FIG. d)). Further, a protective film 6 shown in FIG. When a voltage is applied to the ITO film 2 and the back electrode 5, all the EL layers 3 emit light, and serve as a backlight source for a liquid crystal display (LCD) or a wristwatch, for example.

As described above, in the conventional EL device, the light-transmitting electrode (IT) is provided on the back side of the light-transmitting supporting material to be the light emitting surface.
O), a light emitting layer, a dielectric layer, a back material layer, and a resist layer are formed by screen printing. For this reason, the structure is complicated, the material is expensive and the cost is increased, and the deterioration with time is large.

[0011] As an example of improvement of such a complicated structure, expensive material and deterioration with time, there is, for example, a registered utility model publication No. 3066629 "Circuit board". The circuit board disclosed herein has, as its EL element, a pair of electrodes provided on a substrate of a printed circuit board as a plane, a dielectric layer formed on one or both electrodes, and a light emitting layer formed thereon. And a light-transmitting sealing layer.

In this case, the pair of electrodes has an electrode structure with a planar arrangement. That is, it has a comb-shaped electrode structure in which one electrode is inserted between a plurality of electrodes having the same shape and the other electrode is inserted. In addition, the pair of electrodes has a spiral electrode structure in which two electrodes are arranged in parallel so that adjacent electrodes have opposite poles.

[0013]

As described above, in the above-mentioned conventional example, since the expensive ITO film of the light-transmitting electrode is formed on substantially the entire surface of one of the substrates, the cost is increased, so that it is applicable to a wide range of applications. Not suitable. In addition, since the light emitting surface is formed to be perpendicular to the visual direction, there is a disadvantage that the light emitting efficiency is substantially low.

The present invention solves the above-mentioned problems in the prior art, and minimizes the amount of ITO material, which is a relatively expensive light-transmitting electrode, and reduces its cost. The present invention provides an EL element display device and a method of manufacturing the EL element display device, which can be used in a wide range of applications, and in which the light emitting surface can be formed on one or both surfaces parallel to the visual direction. Aim.

[0015]

In order to achieve the above object, the present invention provides a substrate, a first electrode formed on the substrate, and an electrode formed on at least a part of the first electrode. A light-emitting layer made of a luminescent material, and a second electrode facing the light-emitting layer and formed in a non-conductive state with the first electrode, wherein the substrate and the first electrode or the second electrode
An object of the present invention is to provide a multi-layer EL element display device, wherein at least one side of an electrode is formed of a light transmitting material.

In the present stacked EL device display device, an insulating layer is formed to separate the light emitting layer from the second electrode and to insulate the first electrode from the second electrode. This insulating layer is usually formed of a dielectric. In addition, since both the substrate and the first electrode and the second electrode and the insulating layer are formed of a light-transmitting material, it is possible to provide a structure in which light emission can be visually observed on both surfaces of the light emitting layer.

Further, on the substrate, a first conductive connecting portion for applying a light emitting voltage to which a part of the first electrode is connected, and a light emitting voltage applying portion for connecting a part of the second electrode. And a second conductive connection for forming a wiring pattern formed by screen printing a highly conductive metal on the substrate or by etching the highly conductive metal. Here, the surface shape of the first electrode is formed so as to substantially match that of the light emitting layer. The first electrode having light transmittance uses, for example, indium tin oxide (ITO). The light emitting layer is ZnS, and the highly conductive metal forming the second electrode is Cu or Ag.

In the present laminated EL element display device, a protective layer is formed on the second electrode to improve use durability. Further, the light emitting layer used in the present invention may be a mixed material of an electroluminescent material and a dielectric material.

In the present laminated EL display device, a light-emitting portion constituted by the substrate, the first electrode, the light-emitting layer, the insulating layer and the second electrode is provided on a predetermined area on the substrate. It is formed so as to display a symbol. Here, the symbol can be displayed by printing including colors, excluding the light-emitting portion. Further, by making the substrate deformable, it is possible to dramatically expand the application field of the present device.

The present invention further comprises a first step of forming a light-transmitting conductive first electrode on a light-transmitting substrate by screen printing, and an electroluminescent material on at least a part of the first electrode. A second step of forming a light-emitting layer by screen printing to form an insulating layer covering the light-emitting layer by screen printing, and on the insulating layer, facing the light-emitting layer, and A third method in which the first electrode and the second electrode in a non-conductive state are formed by screen printing.
The present invention provides a method for manufacturing a multi-layer EL element display device, comprising: a step; and a fourth step for drying a forming material in the first to fourth steps.

Here, a first conductive connection portion for applying a light emitting voltage to which a part of the first electrode is connected is formed by screen printing on the substrate, and a part of the second electrode is connected to the first conductive connection portion. The second conductive connection portion for applying a light emitting voltage to be applied is formed by screen printing, and the insulating layer is a light transmitting material having conductivity, and the light transmitting material is formed by screen printing. A dielectric layer is formed between the light emitting layer and the second electrode by screen printing.

With such a configuration, the present laminated EL element display device according to the present invention can reduce the manufacturing cost by reducing the amount of the ITO material, which is an expensive light-transmitting electrode, and can be used in a wide range of applications. It can be used. And
On the front and back sides of the EL element display (both sides of the light-emitting layer), the light emission can be visually observed, so that the light emission on the front side (one side of the light-emitting layer) or the light emission on both sides of the display can be selected. It is possible to improve the degree of freedom of the configuration of the device in which is incorporated.

[0023]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view of a multilayer EL display device according to the present invention;

FIG. 1 is a sectional view showing the structure of an EL device according to the present invention in an embodiment. FIG. 2 is an external perspective view for explaining a manufacturing process of the EL device shown in FIG. 1, and FIG. 3 is a flowchart in the manufacturing process of the EL device corresponding to FIG. Here, the cross-sectional view shown in FIG.
3 shows a cross-sectional structure taken along line B.

In FIG. 1, FIG. 2 and FIG.
The figure shows an EL element having a laminated structure and a manufacturing method thereof.

First, a plurality of wiring connection portions 11a and 11b, each of which is a set of two parallel electrodes, shown in FIG. Carbon paste) is applied by screen printing to form (step C1 in FIG. 2A and FIG. 3). Note that the plurality of wiring connection portions 11a and 11b may be arranged in a wiring pattern formed by etching Cu on the printed circuit board. A liquid crystal display to be illuminated is arranged on the other side of the substrate 10.

Next, a plurality of ITOs shown in FIG. 3 which are circular light-transmitting electrodes on the substrate 10 between the wiring connection portions 11a and 11b and some of the protrusions are connected to the wiring connection portion 11a.
The film 12 is formed by applying by screen printing. Multiple I
For example, when the device is a backlight light source, the TO film 12 is arranged at a plurality of positions where the illumination is effectively performed (step C2 in FIGS. 2B and 3).

Further, on each of the plurality of ITO films 12, a plurality of EL layers 13 shown in FIG. 3 having a circular area slightly smaller than the area of the ITO film 12 are formed. EL layer 13
Is ZnS (containing an active material such as Mn). The plurality of EL layers 13 are formed by applying by screen printing. For example, the coating is performed a plurality of times so as to have a predetermined thickness (FIG. 2C, step C3 in FIG. 3).

Next, a plurality of EL layers 13 and a plurality of ITO
So that each circular part of the membrane 12 is covered,
A plurality of insulating films 14 shown in FIG. 3 are applied by screen printing. For example, the coating is performed a plurality of times so as to have a predetermined thickness (step C4 in FIG. 2D and FIG. 3).

Further, a back electrode 16 is formed on each of the plurality of insulating films 14. This back electrode 16
A plurality of belt-like shapes shown in FIG. 3 which cover at least include the circular portion of the EL layer 13 and extend and connect to the wiring connection portion 11b are formed by applying by screen printing (FIG. 2 ( e) Step C5) in FIG. In addition,
The back electrode 16 is coated with a paste material of Cu or Ag by screen printing.

Next, a protective film (not shown) is formed on the back electrode 16 on the portion 3. Thereafter, a drying step is performed.

An EL produced by such a laminated structure
The element is connected, for example, to DC /
A predetermined frequency and voltage are applied through a DC converter. As a result, all the EL layers 13 emit light on the front surface in the viewing direction, and can be used as a backlight source for a liquid crystal display (LCD) or a wristwatch, for example.

Next, application by screen printing will be described. The plurality of ITO films 12, the EL layers 13, the insulating films 14, and the like are formed by screen printing. The area and the thickness of this coating are determined by the openings formed in the screen mask. In this case, application is performed a plurality of times to form a predetermined thickness.

In the case where the number of the applied portions (light emitting portions) is N, the capacitance becomes N times as large. Also, if the capacitance of each light emitting unit is different, the charging time due to voltage application and the charge amount within a certain time are different, and the light emitting amount and the light emitting speed (light rising time) in each light emitting unit are different. Will change.

For example, when the capacitance is from 7000 pF to 10
In the case of kpF, there is not much difference in the light emission amount between the individual light emitting units, but in the case of 10 kpF to 15 kpF, the light emission amount (illuminance / Lux) decreases to about 2/3.

From these, a liquid crystal display (LCD)
In the case where uniform illuminance over a wide area is required as in the case of the backlight light source, that is, when the application portion (light emitting portion) has a large number of N, the area and the area of the application are adjusted so that the capacitance error does not occur. Manage its thickness. Conversely, by intentionally forming light-emitting portions having different capacitances, it becomes possible to change the light-emission rising speed at the time of blinking light emission or the like.

In the EL device having such a laminated structure, a plurality of ITO films 12, which are light transmitting electrodes, are formed only between the wiring connection portions 11a and 11b. And multiple IT
The O film 12 has a circular shape having an area slightly larger than that of the EL layer 13. Therefore, the expensive light transmitting electrode ITO
The material does not have to be applied to the entire surface of the substrate 10, for example, and the amount of use is minimized, so that the cost can be reduced. This makes it usable for a wide range of applications.

Next, a modification of the EL element shown in FIG. 1 will be described.

When the insulating film 14 is made of a light-transmitting conductive material as the back electrode 16 together with a light-transmitting conductive material, the light emission can be seen from both sides of the light emitting layer (EL layer 13). Become like Therefore, it is possible to select the light emission only on the front side (one surface of the light emitting layer) or the light emission on both surfaces of the light emitting layer, thereby improving the degree of freedom of the configuration (design) of the device incorporating the device.

Further, a dielectric layer in which a dielectric material (for example, a material having light transmissivity) for adjusting the capacitance may be formed between the EL layer 13 and the back electrode 16. The dielectric layer may use a mixed material of an electroluminescent material and a dielectric material.

Next, an application example of the EL element shown in FIG. 1 will be described.

FIG. 4 is a diagram showing a configuration of an application example using the EL element shown in FIG.

FIG. 4A is a front view showing a front configuration, and FIG. 4B is a cross-sectional view showing a main configuration taken along line CC in FIG. 4A.

This example is an application example of a Christmas tree using the EL device having the laminated structure described with reference to FIGS. In FIG. 4A, EL elements 20, 21, and 22 emitting light such as stars and circles are provided on the front surface as a circular ornament.
Are arranged so as to conform to the shape of the Christmas tree.

As shown in FIG. 4 (b), EL
An electronic circuit board 24 for driving and controlling light emission of the EL elements 20, 21, 22,... Is provided together with a button battery 23 serving as a power supply for the elements 20, 21, 22,. The electronic circuit board 24 includes a switching DC /
It is composed of a DC converter and an IC driver or the like that controls the emission order and emission time arbitrarily so as to be preferable for emission display of a Christmas tree.

As is apparent from the above description, the multilayer EL display device of the present invention has a substrate, a first electrode formed on the substrate, and at least a part formed on the first electrode. A light-emitting layer made of an electroluminescent material, and a second electrode facing the light-emitting layer and formed in a non-conductive state with the first electrode.
At least one side of the electrode or the second electrode is formed of a light transmitting material. As a result, the cost can be reduced by minimizing the amount of the ITO material, which is an expensive light-transmitting electrode, and it can be used in a wide range of applications.

Further, in the present invention, since the light emitting surface is formed on one or both surfaces facing the visual direction, a stacked EL having a high visual light emitting efficiency and a very high degree of freedom in configuration is provided.
An element display was realized.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view showing a structure of an EL device according to an embodiment of the present invention.

FIG. 2 is an external perspective view for explaining a manufacturing process of the EL element shown in FIG.

FIG. 3 is a flowchart in a manufacturing process of an EL element corresponding to FIG. 2;

4 is a diagram showing a configuration of an application example using the EL element shown in FIG. (A) is a front view which shows a front structure.
FIG. 3B is a cross-sectional view illustrating a main part structure taken along line CC.

FIG. 5 is a cross-sectional view showing a structure of a conventional EL element.

FIG. 6 is an external perspective view for explaining a manufacturing process of a conventional EL element.

7 is a flowchart of a manufacturing process of the EL element shown in FIG.

[Description of Signs] 10 Substrate 11a, 11b Wiring connection part 12 ITO film 13, 20, 21, 22 EL layer 14 Insulating film 16 Back electrode 23 Button battery 24 Electronic circuit board

Claims (17)

[Claims] 1. A substrate, a first electrode formed on the substrate, a light emitting layer made of an electroluminescent material formed on at least a part of the first electrode, and the first electrode facing the light emitting layer. An electrode and a second electrode formed in a non-conductive state, wherein the substrate and the first electrode or the second electrode
A stacked EL device display device, wherein at least one side of the electrode is formed of a light transmitting material. 2. The multi-layer EL element display device according to claim 1, wherein an insulating layer is formed to separate the light emitting layer and the second electrode and to insulate the first electrode and the second electrode. 3. The substrate, the first electrode, and the second electrode.
3. The multilayer EL device display device according to claim 2, wherein both the electrode and the insulating layer are formed of a light-transmitting material, and have a structure in which light emission is visible on both surfaces of the light-emitting layer. 4. 4. The display device according to claim 3, wherein the insulating layer is formed of a dielectric. 5. A light-emitting voltage applying first conductive connection portion to which a part of the first electrode is connected, and a light-emitting voltage to which a part of the second electrode is connected. The display device according to claim 1, further comprising a second conductive connection portion for applying voltage. 6. The first conductive connection portion and the second conductive connection portion are formed by screen printing a highly conductive metal on the substrate or by etching a highly conductive metal. The display device according to claim 5, wherein the display device is a wiring pattern. 7. The multi-layer EL display device according to claim 1, wherein a surface shape of the first electrode substantially matches a surface shape of the light emitting layer. 8. The display device according to claim 1, wherein a protective layer is formed on the second electrode. 9. The display device according to claim 1, wherein the light emitting layer is a mixed material of an electroluminescent material and a dielectric material. 10. A light-emitting portion including the substrate, the first electrode, the light-emitting layer, the insulating layer, and the second electrode is formed so as to display a predetermined symbol on the substrate. The multilayer EL device display device according to claim 1, wherein: 11. The multi-layer EL element display device according to claim 10, wherein the symbols are displayed by printing including a color except for the light emitting portion. 12. The display device according to claim 1, wherein the first electrode having light transmittance is made of indium tin oxide (ITO). 13. The light emitting layer is made of ZnS.
The display device according to claim 1, wherein the highly conductive metal forming the electrodes is Cu or Ag. 14. The display device according to claim 1, wherein the substrate is deformable. 15. A first step of forming a first electrode having light-transmitting conductivity on a substrate that transmits light by screen printing, and a light-emitting layer made of an electroluminescent material on at least a part of the first electrode. A second step of forming an insulating layer covering the light emitting layer by screen printing, a second step of forming an insulating layer covering the light emitting layer by screen printing, and a first electrode on the insulating layer facing the light emitting layer. And a third step of forming a second electrode in a non-energized state by screen printing, and a fourth step of drying the forming material in the first to fourth steps. A method for manufacturing a multilayer EL element display device. 16. A first conductive connection for applying a light emitting voltage to which a part of the first electrode is connected is formed on the substrate by screen printing, and a part of the second electrode is connected. The method according to claim 15, wherein the second conductive connection for applying the emission voltage is formed by screen printing. 17. The insulating layer is a light-transmitting material having conductivity, the light-transmitting material is formed by screen printing, and a dielectric layer is screen-printed between the light emitting layer and the second electrode. The multilayer EL according to claim 16, which is formed by:
A method for manufacturing an element display device.