Electric lamp and discharge devices – With luminescent solid or liquid material – Solid-state type
Reexamination Certificate
2002-06-25
2004-08-24
Philogene, Haissa (Department: 2821)
Electric lamp and discharge devices
With luminescent solid or liquid material
Solid-state type
C313S506000, C257S072000, C257S383000, C257S761000, C257S766000
Reexamination Certificate
active
06781306
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an organic electro-luminescence device, and more particularly, to an electro-luminescence device, having data lines, gate lines and voltage supplying lines formed from materials that are different from each other and corresponding to each function, and capable of enhancing its characteristics, and to a method of fabricating the same.
2. Discussion of the Related Art
Recently, there has been an increased requirement for a flat panel display device having a small possessory space independent of an enlarged display device. An electro-luminescence device is at the forefront of the flat panel display devices.
The electro-luminescence device is divided into an inorganic electro-luminescence device and an organic electro-luminescence device in accordance with the material used.
The inorganic electro-luminescence device conventionally applies a high electrical field to a light-emitting portion in order to emit light. The high electrical field accelerates electrons and allows the accelerated electrons to be impacted, thereby exciting a light emitting center. During excitation of the light emitting center, the inorganic electro-luminescence device emits the light.
The organic electro-luminescence device injects electrons from a cathode and holes from an anode into a light-emitting portion to transfer excitons from an exciting status to a base status, thereby emitting light. The electron and holes, which are injected into the light-emitting portion are combined to form the exciton.
The inorganic electro-luminescence device having the operation principle as described above requires a high voltage of 100 to 200 volts as a driving voltage because of the application of the high electric field to the light-emitting portion. The organic electro-luminescence device has an advantage that it is driven by a low voltage of about 5 to 20 volts. In light of this point, the organic electro-luminescence device is actively developed.
Also, the organic electro-luminescence device is used for a picture element (or a pixel) of a graphic display, a television image display or a surface light source, owing to its characteristics of wide viewing angle, high-speed response and high contrast. Furthermore, since the organic electro-luminescence device is thin and light and provides a high chrominance, it is adapted for a next generation flat panel display.
FIG. 1
shows an organic electro-luminescence device including gate lines GLl through GLm and data lines DLl to DLn arranged to cross each other on a glass substrate
10
, and picture elements PE arranged at each crossing of the gate lines GLl to GLm and the data line DLl through DLn.
When a gate line on the gate line GLl to GLm is enabled, each picture element PE is driven to generate light corresponding to a video signal on the data line DL.
In order to drive the electro-luminescence device, a gate driver
12
is connected to the gate lines GLl to GLn and a data driver
14
is electrically coupled to the data lines DLl through DLn. The gate line
12
sequentially drives the gate line GLl through GLm. The data driver
14
applies video signals to the picture elements PE through the data lines DLl to DLn.
The picture elements PE driven by the gate driver
12
and the data driver
14
each include an electro-luminescence cell OLED connected to a ground voltage line GND and a cell driving circuit
16
for driving the electro-luminescence cell OLED, as shown in FIG.
2
. The cell driving circuit
16
is connected between the electro-luminescence cell OLED and the ground voltage line GND.
Referring to
FIG. 2
, the cell driving circuit includes a second PMOS TFT (P-channel Metal Oxide Thin Film Transistor) T
2
connected between the electro-luminescence cell OLED and a supply voltage line VDD to drive the electro-luminescence cell OLED, and a first PMOS TFT T
1
connected between the data line DL and a gate electrode of the second PMOS TFT T
2
to switch the picture signal to be applied to the gate electrode of the second PMOS TFT T
2
, and a capacitor Cst connected between a drain electrode of the PMOS TFT T
1
and the supply voltage line VDD.
In explaining an operation of the cell driving circuit in association with a driving waveform diagram of
FIG. 3
, the first PMOS TFT T
1
is turned-on when a low input signal, i.e., a scanning signal from the gate driver
12
is applied to the gate line GL. If the first PMOS TFT T
1
is turned-on, a video signal received synchronously with the scanning signal from the data line DL flows through the first PMOS TFT T
1
and is charged into the capacitor Cst. The video signal has a predetermined amplitude.
The capacitor Cst connected between the drain electrode of the first PMOS TFT T
1
and the supply voltage line VDD charges the video signal applied from the data line DL while the low input signal is supplied to the gate line GL. The capacitor Cst holds the video signal, which is applied from the data line and charged thereinto, during one frame. The holding operation of the capacitor Cst enables the application of the video signal from the data line DL to the electro luminescence device OLED to be maintained.
An organic electro-luminescence device having such a configuration of the picture element PE requires a number of data lines adapted for receiving each image signal such as R(Red), G(Green), B(Blue), etc.
FIG. 4
is a circuit diagram showing another configuration of the conventional picture element PE. The picture element PE of
FIG. 4
includes an electro luminescence cell OLED connected to a ground voltage line GND and a cell driving circuit
26
positioned at a crossing of a data line DL and a gate line GL. The cell driving circuit
26
is connected between the electro luminescence cell OLED and the data line DL.
The cell driving circuit
26
includes a third and fourth PMOS TFT T
3
and T
4
forming a current mirror between the electro luminescence cell OLED and a supply voltage line VDD; a fifth PMOS TFT T
5
connected between the data line DL and the gate line GL to respond to a signal on the gate line GL; a sixth PMOS TFT T
6
connected between nodes of gate electrodes of the third and fourth PMOS TFTs T
3
and T
4
, the gate line GL and the fifth PMOS TFT T
5
; and a capacitor Cst connected between the node of gate electrodes of the third and fourth PMOS TFFs T
3
and T
4
and the supply voltage line VDD.
FIG. 5
explains an operation of the picture element shown in FIG.
4
. The fifth and sixth PMOS TFTs TS and T
6
are turned-on if a low input signal is applied to the gate line GL. When the fifth and sixth PMOS TFTs TS and T
6
are turned-on, a video signal received synchronously with the scanning signal from the data line DL is charged into the capacitor Cst through the fifth and sixth PMOS TFTs T
5
and T
6
. The video signal has a predetermined amplitude.
The capacitor Cst between the node of the gate electrodes of the third and fourth PMOS TFTs T
3
and T
4
charges the video signal from the data line DL while the low input signal is applied to the gate line GL. The capacitor Cst holds the video signal, which is applied from the data line DL and charged thereinto, during one frame. The holding of the capacitor Cst allows the application of the video signal from the data line DL to the electro luminescence cell OLED to be maintained.
An organic electro-luminescence device having such a configuration of the picture element PE requires a number of data lines adapted for receiving each image signal such as R(Red), G(Green), B(Blue), etc.
The video signal, which is charged into the capacitor Cst and held during one frame, is applied to the electro luminescence cell OLED so that an image (or a picture) is displayed on a display panel.
FIG. 5
is a plan view showing the construction of the gate line and the data line of the organic electro-luminescence device in
FIGS. 2 and 4
crossing each other.
Referring to
FIG. 5
, there are data lines DL and supply voltage lines VDD arranged alternatively in the horizontal direction a
LG.Philips LCD Co. , Ltd.
McKenna Long & Aldridge LLP
Philogene Haissa
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