Liquid crystal cells – elements and systems – Particular excitation of liquid crystal – Electrical excitation of liquid crystal
Reexamination Certificate
1998-09-25
2001-01-23
Sikes, William L. (Department: 2871)
Liquid crystal cells, elements and systems
Particular excitation of liquid crystal
Electrical excitation of liquid crystal
C349S139000, C349S141000, C349S143000
Reexamination Certificate
active
06177970
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to liquid crystal displays and a method of manufacturing the same. More particularly, the present invention relates to liquid crystal displays that have electrode arrays for applying electric fields parallel to substrates and thin film transistors as switching elements and a method of manufacturing the same.
2. Description of the Related Art
A liquid crystal display (LCD) having an electrode array for generating an electric field parallel to substrates (IPS mode; in-plane switching mode) is disclosed in U.S. Pat. No. 5,598,285 to Kondo et al.
The IPS mode LCD of Kondo et al. has two substrates opposite each other and a liquid crystal layer therebetween. Two kinds of electrodes for generating an electric field, common electrodes and pixel electrodes, are formed on one of the substrates. An alignment layer is coated on the electrodes.
However, since dielectric layers as a gate insulating layer or passivation layer, which are made of oxide or nitride, are formed on the common electrodes and the pixel electrodes, a potential difference is generated between the electrodes and the alignment layer. As a result, the effective voltage applied to the liquid crystal layer is decreased, and an afterimage appears due to a decrease in the effective voltage. Accordingly, a high driving voltage is required to drive the liquid crystal.
Also, since the two kinds of electrodes are made of different layers and have different thicknesses, the surface of the alignment layer may not be flat, causing non-uniform rubbing which may result in the light leakage.
SUMMARY OF THE INVENTION
In view of the above, it is an object of the present invention to reduce the light leakage and the afterimage, and to lower the driving voltage of an IPS mode liquid crystal display.
These and other objects, features and advantages are provided, according to the present invention, by removing dielectric layers between pixel electrodes and an alignment layer.
Common electrodes and pixel electrodes may be formed on a passivation layer, a gate insulating layer or a transparent insulating substrate, and they directly contact an alignment layer by removing the passivation layer or the gate insulating layer on the electrodes.
Potential difference is not generated between the electrodes and the alignment layer, and the effective voltage applied to the liquid crystal layer is not decreased.
The thickness of the pixel electrode and the common electrode on the passivation layer may be equal to or less than 1,000 Å. It is preferable that the electrodes are tapered.
The alignment layer has a flat surface since the electrodes are relatively thin and tapered. The flat surface enables uniform rubbing, and reduces the leakage of light.
According to the present invention, a gate wire including a gate line delivering a scanning signal and a gate electrode connected to the gate line, and a common signal line are formed on the substrate. A gate insulating layer over the gate wire and the common signal line is formed, and a semiconductor layer on a portion of the gate insulating layer over the gate electrode is formed. A data line crossing the gate line is formed on the gate insulating layer, a source electrode which is connected to the data line is formed on the semiconductor layer, and a drain electrode which is separated from the source electrode is formed on the semiconductive layer. A protection insulating layer covering the source and the drain electrodes and the data line, common electrodes which are connected to the common signal line, and pixel electrodes which are formed respectively between the common electrodes and are connected to the drain electrode are formed on the substrate. An alignment layer aligning liquid crystal material is formed on the common electrodes and the pixel electrodes, to be contacted with the common and the pixel electrodes.
Here, the common electrodes and the pixel electrodes may be formed on the protection insulating layer, the gate insulating layer or the substrate. The protection insulating layer or the gate insulating layer on the common electrodes and the pixel electrodes are removed, to directly contact the alignment layer with common electrodes and the pixel electrodes.
REFERENCES:
patent: 5786876 (1998-07-01), Ota et al.
patent: 5847781 (1998-12-01), Ono et al.
patent: 5852485 (1998-12-01), Shimada et al.
patent: 5892562 (1999-04-01), Yamazaki et al.
patent: 5995182 (1999-11-01), Watanabe et al.
patent: 5995187 (1999-11-01), Wakagi et al.
patent: 6014190 (2000-01-01), Kim et al.
Howrey Simon Arnold & White , LLP
Ngo Julie
Samsung Electronics Co,. Ltd.
Sikes William L.
LandOfFree
In-plane switching mode liquid crystal display and a method... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with In-plane switching mode liquid crystal display and a method..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and In-plane switching mode liquid crystal display and a method... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2468180