JP4169838B2 - EL display device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a display device using electroluminescence (EL), and more particularly to an EL display device that prevents moisture from entering from the periphery of an external electrode.
[0002]
[Prior art]
2. Description of the Related Art Conventionally, there is a display device using an EL light emitting element as a light source of a backlight of a liquid crystal display device or various displays. Conventionally, as this type of EL display device, for example, one having a structure as shown in FIGS. 3 and 4 is known. This EL display device 1 is in the form of a sheet, and a laminated body 6 composed of a back electrode 2, an insulating layer 3, a light emitting layer 4 and a surface electrode 5, and upper and lower surfaces covering the outer surfaces of the back electrode 2 and the surface electrode 5. The hygroscopic material 7a, 7b and the package film 10 with the outer sides of the hygroscopic material 7a, 7b sealed. The back electrode 2 and the front electrode 5 are provided with current collecting bands 8a and 8b, respectively, and electrode lead terminals 9a and 9b are drawn out from the current collecting bands 8a and 8b. The light emitting layer 4 emits light by applying an AC voltage of about 35 to 150 V from the electrode lead terminals 9 a and 9 b between the back electrode 2 and the front electrode 5.
[0003]
[Problems to be solved by the invention]
However, in the conventional EL display device 1 described above, the upper and lower surfaces of the laminate 6 composed of the back electrode 2, the insulating layer 3, the light emitting layer 4 and the front electrode 5 are covered with the moisture absorbents 7a and 7b, and further the package film 10 However, if moisture is externally absorbed from the gap 15 between the electrode lead terminals 9a and 9b drawn out from the back electrode 2 or the front electrode 5, and is used for a long time as it is, the light emitting layer Thus, there was a problem that moisture penetrated to zinc sulfide, which is the luminescent agent No. 4, and discolored the luminescent layer 4 to cause a decrease in life and a decrease in luminance.
[0004]
Therefore, the present invention provides an EL display device that suppresses a decrease in EL light emission lifetime and light emission luminance by reliably preventing moisture from entering from each electrode terminal portion of the back electrode and the front electrode. It is.
[0005]
[Means for Solving the Problems]
In order to solve the above-described problem, an EL display device according to claim 1 of the present invention covers a back electrode, an insulating layer, a light-emitting layer, and a surface electrode, which are sequentially stacked on a substrate, with a sealing material, In an EL display device in which a light emitting layer emits light by applying an alternating voltage between the surface electrode and the substrate, a pair of through-hole electrodes are provided on the substrate, and the viscosity of the through-hole electrode on the back electrode side of the substrate is higher An external extraction electrode made of a highly conductive paint is provided to close the through hole, and the back electrode and the front electrode are electrically connected to the external extraction electrode, respectively, and on the side opposite to the back electrode side of the substrate Each of the external electrodes is provided to be electrically connected to each through-hole electrode.
[0006]
Further, EL display devices according to claim 2 of the present invention, the external take-out electrode, characterized in that it is formed by printing overlapping the top of the through-hole electrode.
[0007]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of an EL display device according to the present invention will be described below with reference to the accompanying drawings. FIG. 1 shows a cross-sectional structure of an EL display device 12 according to the present invention. In this EL display device 12, a back electrode 2, an insulating layer 3, a light emitting layer 4 and a front electrode (ITO electrode) 5 are sequentially laminated on the surface of a substrate 13 such as glass, and the whole is sealed with transparent glass or resin. The structure is covered with a stopper 14. In addition, through holes penetrating the upper and lower surfaces are formed at appropriate two locations in the substrate 13, and through-hole electrodes 18 a and 18 b respectively connected to the back electrode 2 and the front electrode 5 are formed in the respective through holes.
[0008]
On the other hand, on the upper surface side of the substrate 13, an external extraction electrode 16a of the back electrode 2 and an external extraction electrode 16b of the front electrode 5 are formed so as to block the through-hole electrodes 18a and 18b, respectively. Further, external electrodes 17a and 17b are provided on the lower surface side of the substrate 13 at the periphery of the through-hole electrodes 18a and 18b, respectively, and the external extraction electrode 16a and the external electrode 17a on one side connect the through-hole electrode 18a. The external extraction electrode 16b and the external electrode 17b on the other side are electrically connected via the through-hole electrode 18b.
[0009]
The through-hole electrodes 18a and 18b and the external extraction electrodes 16a and 16b are formed of a conductive paint such as silver-palladium. First, silver-palladium paint having a certain degree of viscosity is placed on the through hole of the substrate 13 from the back electrode 2 side, and this is sucked from the opposite side of the substrate 13 so that the silver-palladium paint falls down, and the through hole Through-hole electrodes 18a and 18b are formed by adhering to the inner peripheral surface of the electrode. Next, when the silver-palladium paint having a slightly higher viscosity is placed on the through hole in the same manner as described above and sucked from the opposite side of the substrate with a suction force weaker than before, the silver-palladium paint is deformed into a flat shape. Thus, the upper surfaces of the through holes are closed, and external extraction electrodes 16a and 16b connected to the through hole electrodes 18a and 18b are formed. In this way, after printing the silver-palladium paint twice in succession, this is baked at a high temperature around 750 ° C. to form both electrodes. Finally, silver-palladium paint is printed around the through-hole from the opposite side of the substrate 13 to form external electrodes 17a and 17b connected to the through-hole electrodes 18a and 18b, which are again baked at a high temperature around 750 ° C. To do. Thus, since the board | substrate 13 is exposed to high temperature many times, it is desirable to utilize high heat resistant glass. It goes without saying that the external electrodes 17a and 17b can be configured to close the through holes in the same manner as the external extraction electrodes 16a and 16b. It is also possible to use conductive paints other than silver-palladium.
[0010]
The back electrode 2 is formed on the upper surface of the substrate 13. The back electrode 2 is formed by vapor-depositing a highly conductive silver powder on the substrate 13 or screen-printing a conductive paint on the substrate 13. Or the like. The back electrode 2 is formed so as to overlap the above-described external extraction electrode 16a, but an insulating space 22 is provided around it so as not to contact the external extraction electrode 16b on the surface electrode 5 side. The insulating space 22 can be easily formed by covering the external extraction electrode 16b and the periphery thereof with a mask when the back electrode 2 is formed.
[0011]
An insulating layer 3 is formed on the back electrode 2 by printing. This insulating layer 3 is for protecting the light emitting layer 4 from electrical breakdown, and barium titanate having a high withstand voltage is used. Since the paint in which barium titanate is dispersed has high light reflectance, it also serves as a reflector that reflects light emitted from the light emitting layer 4 toward the surface electrode 5 side. When the insulating layer 3 is printed, a circular space 23 is formed around the external extraction electrode 16b so as to escape from the external space 16 corresponding to the insulating space 22. The size of the circular space 23 is the insulating space 22 described above. Formed slightly smaller. By forming the circular space 23 slightly smaller than the insulating space 22 in this way, a step portion 24 is formed between the edge of the insulating space 22 of the back electrode 2 and the edge of the circular space 23 of the insulating layer 3. It will be.
[0012]
The light emitting layer 4 laminated on the insulating layer 3 is formed by dispersing phosphor powder in an organic binder. Zinc sulfide (ZnS) is used as the base material of the phosphor powder, and various luminescent colors can be obtained by adding Cu, Cl, I, or Mn atoms as activators or coactivators serving as emission centers. . The fluorescent matrix to which such an activator is added is made into a paint, and this is screen-printed to form the light emitting layer 4 having a thickness of about 50 to 100 μm on the insulating layer 3. Also during this printing, a circular space 25 having the same size as the circular space 23 of the insulating layer 3 is provided so as not to contact the external extraction electrode 16b.
[0013]
After laminating the back electrode 2, the insulating layer 3, and the light emitting layer 4 as described above, the surface electrode 5 is printed on the light emitting layer 4, and at this time, the surface electrode 5 is formed in the circular space 25 of the light emitting layer 4, It also enters the circular space 23 of the insulating layer 3 and the insulating space 22 of the back electrode 2 and is printed on the upper surface of the external extraction electrode 16b. Since the circular space 25 of the light emitting layer 4 and the circular space 23 of the insulating layer 3 are smaller than the insulating space 22 of the back electrode 2 and the stepped portion 24 is formed between the circular space 23 and the insulating space 22, the surface electrode 5 and the external extraction electrode 16b are not in contact with the back electrode 2, and the insulation between the back electrode 2 and the front electrode 5 is maintained. The conductive portion 20 may contact the insulating layer 3 and the light emitting layer 4.
[0014]
The coating material for forming the surface electrode 5 is a coating material obtained by doping indium oxide with tin oxide and mixing ITO (Indium Tin Oxide) powder with a transparent resin.
[0015]
The back electrode 2, the insulating layer 3, the light emitting layer 4, and the front electrode 5 sequentially laminated on the substrate 13 are entirely covered with a sealing material 14, and a sealing agent that coats the sealing material 14 around the substrate 13. It is sealed by adhering to 19. The sealing material 14 protects the light emitting layer 4 from external moisture and transmits light emitted from the light emitting layer 4, and is made of a material such as light transmissive glass, metal, or epoxy resin. The Further, as the sealant 19, a silicon resin, an acrylic resin, an epoxy resin, or the like is used, and is cured by any one of room temperature curing, heat curing, and UV (ultraviolet) curing.
[0016]
In the EL display device 12 having such a configuration, one through-hole electrode 18a is electrically connected to the back electrode 2 through the external extraction electrode 16a, and the other through-hole electrode 18b is connected to the external extraction electrode 16b and the conduction part 20. Since it is electrically connected to the front electrode 5, a predetermined AC voltage can be applied between the back electrode 2 and the front electrode 5 from the external electrodes 17 a and 17 b by surface mounting the EL display device 12 on the mother board 21.
[0017]
Further, since the through-hole electrodes 18a and 18b opened in the EL substrate 13 are closed by the external extraction electrodes 16a and 16b, it is possible to reliably prevent moisture from the outside from entering the inside through the through-hole electrodes 18a and 18b. can do. Further, in this embodiment, since the inside is sealed by the substrate 13 and the sealing material 14, moisture does not enter the inside from other parts.
[0018]
【The invention's effect】
As described above, according to the EL display device of the present invention, the through-hole electrode provided on the substrate is closed by the external extraction electrode, and the entire EL is completely sealed with the sealing material. Moisture and moisture do not enter the EL, and EL life and emission luminance can be prevented from decreasing.
[0019]
Also, according to the EL display device of the present invention, the external extraction electrode is formed by being printed over the through-hole electrode with a conductive paint having a higher viscosity than the through-hole electrode. Can be reliably blocked, and moisture can be completely prevented from entering from the through-hole electrode.
[0020]
In addition, since the back electrode and the external electrode drawn from the front electrode are formed on the back side of the substrate, the EL display device can be directly mounted on the mother board, and the SMD (Surface-Mounted Device) type LED or chip resistor Connection with circuit components such as a chip capacitor becomes easy.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view showing a configuration of an EL display device according to the present invention.
FIG. 2 is a bottom view of an EL display device according to the present invention.
FIG. 3 is a perspective view showing a configuration of a conventional sheet-like EL display device.
FIG. 4 is a cross-sectional view of a conventional sheet-like EL display device.
[Explanation of symbols]
2 Back electrode 3 Insulating layer 4 Light emitting layer 5 Front surface electrode 12 EL display device 13 Substrate 14 Sealing material 16a, 16b External extraction electrodes 17a, 17b External electrodes 18a, 18b Through-hole electrodes

Claims (2)

An EL display device in which a back electrode, an insulating layer, a light emitting layer, and a surface electrode sequentially laminated on a substrate are covered with a sealing material, and an AC voltage is applied between the back electrode and the surface electrode to cause the light emitting layer to emit light In
A pair of through-hole electrodes is provided on the substrate, and an external extraction electrode formed of a conductive paint having a viscosity higher than that of the through-hole electrode is provided on the back electrode side of the substrate of the through-hole electrode so as to close the through-hole. An EL display device comprising: an electrode, a surface electrode, and the external extraction electrode are electrically connected to each other; and an external electrode that is electrically connected to each through-hole electrode is provided on a side opposite to the back electrode side of the substrate. . The external take-out electrode, EL display devices according to claim 1, wherein the printed formed overlapping the top of the through-hole electrode.

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