Electric lamp and discharge devices – With luminescent solid or liquid material – Solid-state type
Reexamination Certificate
1998-05-18
2002-04-16
Patel, Ashok (Department: 2879)
Electric lamp and discharge devices
With luminescent solid or liquid material
Solid-state type
C313S504000, C313S509000, C427S066000
Reexamination Certificate
active
06373187
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to a display panel and a method for the manufacture thereof, in particular to a display panel using organic electroluminescent material and a method for manufacturing the same.
FIG. 7
illustrates an arrangement of luminescent picture elements in a conventional full-color display panel using organic electroluminescent material. As shown in
FIG. 7
, the conventional display panel has a plurality of luminescent picture elements
101
arranged in matrix manner. Each picture element
101
includes a red luminescent unit R, a green luminescent unit G and a blue luminescent unit B, all extending in a predetermined direction so as to form a stripe pattern on the display.
FIG. 8
illustrates the structure of a base section
101
a
mounting the luminescent picture elements
101
. As shown in
FIG. 8
, the base section
101
a
has a plurality of first type electrodes
103
consisting of ITO, which are formed on the surface of one side of a transparent glass substrate
102
. Further, a plurality of electrically insulating layers
104
and a plurality of electrically insulating partition walls
105
are provided at a predetermined interval over the first type electrodes
103
on the glass substrate
102
, in a manner such that both the layers
104
and the walls
105
are orthogonal to and partially cover the electrodes
103
.
Referring again to
FIG. 8
, a plurality of thin layers
106
of an organic electroluminescent material are formed in parallel with the layers
104
and partition walls
105
on exposed portions of the electrodes
103
, a plurality of second type electrodes
107
are formed over the thin layers
106
so that both the electrodes
107
and the thin layers
106
are arranged in the same direction as the partition walls
105
.
As shown in
FIG. 8
, the plurality of second type electrodes
107
are separated from one another by the partition walls
105
so as to prevent a possible electric short between two adjacent electrodes
107
. Further, in order to exactly separate two adjacent electrodes
107
, it is preferred that each partition wall
105
be formed to have an inverted trapezoidal cross section.
However, since both the electroluminescent layers
106
and the partition walls
105
are all apt to be affected by a moisture, it is necessary to provide a glass cover or a protection layer on the transparent glass substrate
102
to cover up the organic electroluminescent layers
106
and the partition walls
105
, as shown in FIG.
9
.
FIG. 9
a
is a cross sectional view illustrating a display panel base section
101
a
including a plurality of picture elements which are sealed up by a glass cover
108
.
FIG. 9
b
is a cross sectional view illustrating a display panel base section
101
a
including a plurality of picture elements ire sealed up by a protection layer
109
having a moisture proof property.
In use, the first type electroeds
103
and the second type electrodes
107
are energized, so that some portions of the organic electroluminescent layers
106
corresponding to intersections of the first type electrodes
103
with the second type electrodes
107
, are caused to emit lights which are displayed through the transparent glass substrate
102
.
A process for manufacturing a display panel base section
101
a
may be described in the following with reference to
FIGS. 10
a
-
10
c.
At first, as shown in
FIG. 10
a,
a plurality of first type electrodes
103
consisting of an electrically conductive transparent material such as ITO are formed on the transparent glass substrate
102
. Then, a plurality of partition walls
105
are formed on the glass substrate
102
. Each partition wall
105
has a cross section formed into an inverted trapezoidal shape having an overhang angle &thgr; with a vertical axis X.
Subsequently, as shown in
FIG. 10
b,
with the use of a mask
111
punched in accordance with a predetermined pattern, the organic electroluminescent layers
106
corresponding to red luminescent unit R and green luminescent unit G and blue luminescent unit B, are formed on exposed portions of the first type electrodes
103
.
Finally, as shown in
FIG. 10
c,
a metal of low electric resistance such as Al, Cu or Au is vapor depositted on the organic electroluminescent layers
106
so as to form thereon a plurality of second type electrodes
107
.
When the above metal is vapor depositted, the deposition direction is usually controlled to be perpendicular with respect to the substrate
102
, so that the metal may be prevented from being depositted onto the side surfaces of the partition walls
105
. In this way, the metal depositted on the top of each partition wall
105
is separated from adjacent second type electrodes
107
, thereby preventing any possible electric short between two adjacent electrodes
107
.
However, with the above method for producing a display panel, there is a possibility that some of the partition walls
105
will be partially broken, and another possibility that some fine contaminants or particles will attach to the side surfaces or the surrounding areas of the partition walls
105
. As a result, when a metal is vapor depositted to form the second type electrodes
107
, two adjacent electrodes
107
will be undesirably connected through the above fine contaminates or particles.
FIG. 11
is a cross sectional view indicating a condition where two adjacent electrodes
107
together with two organic electroluminescent layers
106
on both sides of a partition wall
105
are undesirably connected to each other through a mass of fine particles attached on the side surfaces of the partition wall
105
. Accordingly, it is impossible to prevent electric short between two adjacent electrodes
107
.
SUMMARY OF THE INVENTION
It is an object of the present invention to provide an improved display panel capable of exactly isolating two second type electrodes even if they are disposed very close to each other, so as to solve the above-mentioned problems peculiar to the above-mentioned prior art.
According to the present invention, there is provided an improved display panel using an organic electroluminescent material, comprising: a substrate; a plurality of first type electrodes formed on the surface of one side of the substrate; a plurality of electrically insulating partition wall groups each including a plurality of partition walls, partially covering and partially exposing the first type electrodes; a plurality of organic electroluminescent layers formed on exposed portions of the first type electrodes; and a plurality of second type electrodes formed on the organic electroluminescent layers. In particular, each partition wall group has one or more internal spaces each formed between two adjacent partition walls.
In more detail, there is provided an improved display panel which employs an organic electroluminescent material and in which a plurality of luminescent units are arranged in a matrix manner, said display panel comprising: a substrate; a plurality of first type electrodes arranged in parallel with one another at a predetermined interval on the surface of one side of the substrate; a plurality of electrically insulating partition wall groups each including a plurality of partition walls, partially covering and partially exposing the first type electrodes, arranged at a predetermined interval in a direction orthogonal to the first type electrodes on the substrate; a plurality of organic electroluminescent layers formed on exposed portions of the first type electrodes, arranged in parallel with said partition walls; and a plurality of second type electrodes formed on the organic electroluminescent layers in parallel therewith, each disposed between two adjacent partition wall groups. In particular, each partition wall group includes a plurality of partition walls arranged in parallel with one another at a predetermined interval, producing one or more internal spaces each formed between two adjacent partition walls.
In one aspect of the present invention, an elongated internal
Nagayama Kenichi
Watanabe Teruichi
Arent Fox Kintner & Plotkin & Kahn, PLLC
Patel Ashok
Pioneer Electronic Corporation
Santiago Mariceli
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