Electric lamp and discharge devices – With luminescent solid or liquid material – Solid-state type
Reexamination Certificate
2002-02-08
2004-08-31
Patel, Ashok (Department: 2879)
Electric lamp and discharge devices
With luminescent solid or liquid material
Solid-state type
C313S504000, C445S025000
Reexamination Certificate
active
06784612
ABSTRACT:
CROSS REFERENCE TO RELATED APPLICATIONS
This application claims the benefit of Korean Patent Application No. 2001-46018, filed on Jul. 30, 2001, in the Korean Industrial Property office, the disclosure of which is incorporated herein by reference.
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a flat panel display device, and more particularly, to an organic electroluminescent (EL) display device and a method of encapsulating the same.
2. Description of Related Art
Examples of a flat panel display device include a liquid crystal display (LCD) device, an organic EL display (OELD) device, a field emitter display (FED) device, and a plasma display panel (PDP). Of these, the organic EL display device attracts attention due to a wide viewing angle, a clearer moving picture, a high durability, and a high temperature resistance.
FIG. 1
is a cross-sectional view illustrating a conventional organic EL display device. The organic EL display device includes a lower electrode
12
, an organic EL layer
14
, and an upper electrode
16
which are sequentially stacked on a transparent insulating substrate (“insulating substrate”)
10
.
A structure that emits light from the organic EL layer
14
toward the insulating substrate
10
is referred to as a back surface light emitting structure, and a structure that emits light from the organic EL layer
14
toward a direction opposite to the insulating substrate
10
is referred to as a front surface light emitting structure.
In case of the back surface light emitting structure, the lower electrode
12
is made of a transparent conductive material, and the upper electrode
16
is made of an opaque conductive material. On the other hands, in case of the front surface light emitting structure, the lower electrode
12
is made of an opaque conductive material, and the upper electrode
16
is made of a transparent conductive material.
Hereinafter, the organic EL display device is described focusing on the back surface light emitting structure.
The lower electrode
12
is made of a transparent conductive material including one of indium tin oxide (ITO) and indium zinc oxide (IZO), and the upper electrode
16
is made of an opaque conductive material including one of magnesium, aluminum, indium, and silver-magnesium.
A passivation layer (not shown) can be formed over the entire surface of the insulating substrate
10
to cover an organic EL element
18
.
A metal cap
20
is attached to the insulating substrate
10
using an adhesive
22
to encapsulate the organic EL element
18
so as to protect the organic EL display from oxygen or moisture. The metal cap
20
is made of an aluminum alloy. A moisture/water absorbing layer
24
is arranged on an inner surface of the metal cap
20
to prevent element characteristics (e.g., a light-emitting efficiency) from being deteriorated due to the moisture or water.
FIG. 2
shows a flow chart illustrating a process of encapsulating the organic EL display device of FIG.
1
. The lower electrode
12
, the organic EL layer
14
, and the upper electrode
16
are sequentially formed on the insulating substrate
10
(operation
202
). The adhesive
22
is coated on a periphery region of the insulating substrate
10
to a thickness of about 150 &mgr;m (operation
204
). The metal cap
20
is rested on the adhesive
22
and pressurized to attach the metal cap
20
to the insulating substrate
10
(operation
206
). The adhesive
20
is cured at a predetermined temperature using a UV light (operation
208
). Accordingly, encapsulation of the organic EL element
18
is completed.
However, the conventional encapsulating method has at least the following problems. As the adhesive
22
is pressurized by the metal cap
20
, the thickness of the adhesive
22
is reduced to ~50 &mgr;m. Therefore, an inner pressure of a space formed by the insulating substrate
10
and the metal cap
20
is increased. Also, as the adhesive
22
is cured using a UV light, a gas volume of the space causes a thermal expansion. As a result, the adhesive
22
can be separated from the insulating substrate
10
and can have a non-uniform width. Accordingly, moisture can leak into the space, thereby deteriorating element characteristics of the organic EL display device.
In addition, the conventional organic EL display having the structure described above cannot satisfy a current trend toward a compact display device.
SUMMARY OF THE INVENTION
Accordingly, it is an object of the present invention provide an organic EL display device having improved element characteristics.
It is another object of the present invention to provide an organic EL display device having a compact structure.
Additional objects and advantages of the invention will be set forth in part in the description which follows and, in part, will be obvious from the description, or may be learned by practice of the invention.
To achieve the above and other objects of the present invention, there is provided an organic electroluminescent (EL) display device, comprising a substrate, an organic EL element having a lower electrode, an organic EL layer and an upper electrode sequentially stacked on the substrate, a flat panel which encapsulates the organic EL element and is attached to the substrate, at least one through hole formed in the substrate and/or the flat panel, and a through hole shutting cap which shuts the through hole.
To achieve the above and other objects of the present invention, there is also provided a method of encapsulating an organic EL display device, comprising providing at least one through hole in a substrate and/or a flat panel, forming an organic EL element including a lower electrode, an organic EL layer and an upper electrode that are sequentially stacked on the substrate, coating an adhesive on the substrate and/or the flat panel, attaching the substrate and the flat panel to each other, curing the adhesive at a predetermined temperature, and shutting the through hole.
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Kim Hun
Park Jin-Woo
Song Seung-Yong
Colón German
Patel Ashok
Samsung SDI & Co., Ltd.
Staas & Halsey , LLP
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