Electric lamp and discharge devices – With luminescent solid or liquid material – Solid-state type
Reexamination Certificate
2001-03-23
2003-09-30
Patel, Ashok (Department: 2879)
Electric lamp and discharge devices
With luminescent solid or liquid material
Solid-state type
C313S504000
Reexamination Certificate
active
06628069
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to a structure and a method of manufacturing organic electroluminescent (EL) elements. More particularly, it is related to patterns of icons of organic electroluminescent (EL) elements manufactured by ramparts.
BACKGROUND OF THE INVENTION
On the display panels of portable personal digital assistants and cell phones, some display information characteristics, e.g. residual power, signal intensity, call-ringing and envelope, are shown by icons instead of array type display panels. Therefore, a low-resolution problem caused by array type display panels is solved.
Referring to
FIG. 1A
, it is a cross-sectional view of a conventional structure using an organic EL element to form a pattern on the display panel.
FIG. 1B
is a top view of a first display electrode.
As shown in
FIG. 1A
, the organic EL element includes a first display electrode
22
, i.e. an Indium-tin Oxide (ITO) film, formed on a substrate
21
which is composed of light-transparent glass. A pattern of the first electrode
22
formed by etching the ITO film is shown in FIG.
1
B. An organic function layer
23
, including a stacked structure of a hole injection layer, a hole transport layer, an emitting layer, an electron transport layer and an electron injection layer, and a second display electrode
24
are layered in turn on the substrate
21
and first display electrode
22
. When a specific voltage is applied to the first and second display electrodes
22
and
24
, a current flows through an area of the organic function layer
23
between electrodes
22
and
24
, the light-emitting area of organic function layer
23
emits a corresponding pattern of an icon showed in FIG.
1
B.
Such pattern of the icon, which comes from an organic EL element by utilizing the above method is defined by a first display electrode
22
. However, the first display electrode
22
and the substrate
21
are made of different materials, so that their reflectivities, transmissivities and refractive indexes are not equivalent. Then, the defects of the pattern of an icon are visible from the side of the substrate
21
while no voltage is applied between these electrodes.
To improve the above disadvantages, U.S. Pat. No. 5,949,186 of Pioneer Electronic Corporation, entitled “organic electroluminescent element” (issued date, Sep. 7, 1999) shows a structure using the organic EL element to manufacture icons in a display panel.
Referring to
FIG. 2A
, it is a cross-sectional view of a conventional structure using the organic EL element to form a pattern on the display panel.
FIG. 2B
is a top view of an electron injection layer.
As shown in
FIG. 2A
, the organic EL element includes a first display electrode
32
, i.e. an ITO film, formed on a substrate
31
. An organic function layer is layered on the first display electrode
32
. The organic function layer includes an electron injection layer
34
having a pattern shown in
FIG. 2B
, and a combined layer
33
composed of a hole injection, a hole transport layer, an emitting layer, and an electron transport layer. A second display electrode
35
is thereafter formed on the organic layers. When a specific voltage is applied to the first and second electrodes
32
and
35
, a current flows through only an area of the organic function layer, which is defined by an electron injection layer
34
, and the light-emitting area creates a corresponding pattern of an icon shown in FIG.
2
B.
Referring to
FIG. 3A
, it is a cross-sectional view of a conventional structure using the organic EL element to form a pattern on the display panel.
FIG. 3B
is a top view of a hole injection layer.
As shown in
FIG. 3A
, the organic EL element includes a first display electrode
42
, i.e. an ITO film, formed on substrate
41
. An organic function layer is layered on the first display electrode
42
. The organic function layer includes a hole injection layer
48
having a pattern shown in
FIG. 3B
, and a combined layer
49
composed of a hole transport layer
48
, an emitting layer, an electron transport layer, and an electron injection layer. A second display electrode
40
is layered on the organic function layer. When a specific voltage is applied to the first and second electrodes
42
and
40
, a current flows through only an area of the organic function layer, which is defined by the hole injection layer
48
, and the light-emitting area generates a corresponding pattern of an icon shown in FIG.
3
B.
Referring to
FIG. 4A
, it is a cross-sectional view of a structure of a conventional method using the organic EL element to form a pattern on the display panel.
FIG. 4B
is a top view of an electron obstruction layer.
As shown in
FIG. 4A
, the organic EL element includes a first display electrode
50
, i.e. an ITO film, formed on substrate
59
. An organic function layer
51
is layered on the first display electrode
50
. An electron obstruction layer
52
having a pattern, shown in
FIG. 4B
, is formed on the organic function layer
51
. Then, a second display electrode
53
is layered both on the organic function layer and the electron obstruction layer. When a specific voltage is applied to the first and second electrodes
50
and
53
, a current flows through only an area of the organic function layer, which is not determined by the electron obstruction layer
52
, and the light-emitting area produces, a corresponding pattern
57
of an icon shown in FIG.
4
B.
Referring to
FIG. 5A
, it is a cross-sectional view of a structure of a conventional method using the organic EL element to form a pattern on the display panel.
FIG. 5B
is a top view of a hole obstruction layer.
As shown in
FIG. 5A
, the organic EL element includes a first display electrode
62
, i.e. an ITO film, formed on substrate
61
. A hole injection layer
67
covered with the organic function layer is layered on the first display electrode
62
. A hole obstruction layer having a pattern shown in
FIG. 5B
is formed on the hole injection layer. Then, a combined layer
69
stacked with a hole transport layer, an emitting layer, an electron transport layer and an electron injection layer, and the second display electrode
66
are layered on the hole injection layer and the hole obstruction layer. When a specific voltage is applied to the first and second electrodes
62
and
66
, a current flows through only an area of the organic functioning layer, which is not determined by the hole obstruction layer
52
, and the light-emitting area brings a corresponding pattern
63
of an icon shown in FIG.
5
B.
The organic EL element shown by Pioneer Electronic Corporation uses the ITO film as the continuous surface. However, during the process of manufacturing patterns on an electron injection layer, a hole injection layer, an electron obstruction layer or hole obstruction layer, the formation of patterns is utilizing metal mask process for evaporation that increase the complex as well as the disadvantages of pollution and vulnerable pattern control. In addition, the metal mask processes are not compatible with the conventional method of manufacturing an array type display panel. So the processes of the array type display panel and the organic EL element must be divided, and it increases the complexity of manufacturing the display panel.
SUMMARY OF THE INVENTION
One aspect of the present invention is to provide a structure and a method of manufacturing an organic EL element. Initially, a rampart is formed on the ITO film with continuous surface, to define a pattern of an icon. The organic function layer and electrodes are then formed.
The present invention is also provides a structure and a method of manufacturing an organic EL element. The rampart of the present invention is used to separate the organic function layer and the second display electrode so as to, avoid the additional metal mask process on the organic function layer or the second display electrode for pattern formation, and to further reduce the cost of evaporation process.
Another aspect of the present invention is to provid
Chung Chia-Tin
Chung Mao-Jung
Guo Hong-Ru
Lee Yao-Hui
Chi Mei Optoelectronics Corp.
Patel Ashok
Stroock & Stroock & Lavan LLP
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