Liquid crystal cells – elements and systems – Particular excitation of liquid crystal – Electrical excitation of liquid crystal
Reexamination Certificate
2000-03-14
2001-10-23
Parker, Kenneth (Department: 2871)
Liquid crystal cells, elements and systems
Particular excitation of liquid crystal
Electrical excitation of liquid crystal
Reexamination Certificate
active
06307602
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a liquid crystal display (LCD) and a method of manufacturing the same, and more particularly, to an LCD and a method of manufacturing the LCD which is capable of preventing electrical shorts between neighboring pixel electrodes.
2. Description of Background Art
A conventional LCD is driven by an active matrix method which employs thin film transistors (TFTs), signal lines, data lines and others for driving the pixels. Such a conventional LCD is widely used as a display device in audio-video (AV) and official-automation (OA) systems. The conventional LCD has a thinner thickness, a smaller size, a lighter weight, and a lower power consumption than other display devices, such as a cathode-ray-tube (CRT) device. Further, the conventional LCD has a good response speed and display quality for displaying moving video data.
FIG. 1
shows the structure of a conventional active matrix liquid crystal display (AMLCD) device.
As shown in
FIG. 1
, on a transparent insulation substrate (such as non-alkalic glass), a plurality of scan lines
10
extending in a horizontal direction and a plurality of data lines
20
extending in a vertical direction are formed. A pixel electrode
30
is formed in an area defined by two adjacent scan lines
10
and two adjacent data lines
20
. A TFT
40
is electrically connected with the pixel electrode
30
, the scan line
10
, and the data line
20
. The pixel electrode
30
overlaps a portion of the scan line
10
. An insulating layer is formed between the pixel electrode
30
and scan line
10
. The overlapping portion
6
f the pixel electrode
30
and the overlapped portion of the scan line
10
function as the electrodes of a storage capacitor
70
.
FIG. 2
shows a section of a storage capacitor and pixel electrodes in the conventional LCD.
As shown in
FIG. 2
, a metal segment
50
is formed on a gate insulation layer (not shown) covering the scan line
10
. The metal segment
50
covers a portion of the scan line
10
, whereas a protection layer (not shown) covers the metal segment
50
. The metal segment
50
is electrically connected with the pixel electrode
30
through a storage contact hole
60
which exposes a surface of the metal segment
50
. The overlapping portion of the pixel electrode
30
, the metal segment
50
and the overlapped portion of the scan line
10
function as the electrodes of the storage capacitor
70
.
FIG. 3
shows a cross-sectional view of
FIG. 2
, taken along line III—III.
As shown in
FIG. 3
, a scan line
10
made with an aluminum (Al) or chromium (Cr) metal is formed on a transparent insulation substrate
1
. A gate insulation layer
11
including silicon oxide or silicon nitride covers the entire surface of the substrate
1
. On the gate insulation layer
11
, a metal segment
50
having Al or Cr is formed. A protective insulating layer (passivation layer)
17
having silicon nitride covers the metal segment
50
. A storage contact hole
60
is formed through the passivation layer
17
for exposing a surface of the metal segment
50
. On the passivation layer
17
, a pixel electrode
30
having ITO (Indium Tin Oxide) is formed. The pixel electrode
30
is electrically connected with the metal segment
50
through the storage contact hole
60
.
In the conventional LCD, however, the neighboring pixel electrodes are positioned to close to each other because each pixel electrode overlaps a substantial portion of the scan line. The overlapping portion of the pixel electrode is positioned too close to the neighboring pixel electrode. When the storage capacitor is not formed or is formed by another method, the distance between the neighboring pixel electrodes is 6 &mgr;m which is greater than the width of the scan line (30 &mgr;m).
Because the neighboring pixel electrodes are positioned so close to each other, when the data signal driven by the TFT is applied to one of the pixel electrodes, the neighboring pixel can be inadvertently driven, causing the pixel electrodes to be shorted out. When the pixel electrode short occurs, the display has point defects and poor color quality.
SUMMARY OF THE INVENTION
Accordingly, the present invention is directed to an LCD and a method of manufacturing the same that substantially obviates one or more of the above and other problems due to limitations and disadvantages of the related art.
An object of the present invention is to overcome the problem of shorts between pixel electrodes in the conventional LCDs.
Another object of the present invention is to provide an LCD with high display quality and a method of manufacturing the same.
According to the embodiments of the present invention, an LCD includes a transparent insulation substrate, a plurality of scan lines and data lines formed on the substrate and perpendicularly crossing each other, an insulation layer covering the scan lines, a metal segment formed on the insulation layer overlapping a part of one of the scan lines, a pixel electrode electrically connected with the metal segment and formed in an area surrounded by two neighboring scan lines and two neighboring data lines, and a TFT electrically connected with the pixel electrode, the scan line and the data line.
A method of manufacturing an LCD according to the embodiments of the present invention includes the steps of forming a scan line on a transparent insulation substrate, forming an insulation layer on the scan line, forming a metal segment overlapping with a part of the scan line, forming a passivation layer, forming a contact hole in the passivation layer for exposing a surface of the metal segment, and forming a pixel electrode for contacting with the metal segment through the contact hole.
In one embodiment, each pixel electrode includes at least one expanded portion projecting toward the corresponding metal segment so as to allow the pixel electrode to contact the corresponding metal segment through a contact hole. In another embodiment, each metal segment includes at least one expanded portion projecting toward the corresponding pixel electrode so as to allow the pixel electrode to contact the metal segment through a contact hole.
Further scope of applicability of the present invention will become apparent from the detailed description given hereinafter. However, it should be understood that the detailed description and specific examples, while indicating preferred embodiments of the invention, are given by way of illustration only, since various changes and modifications within the spirit and scope of the invention will become apparent to those skilled in the art from this detailed description.
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LG Electronics Inc.
Parker Kenneth
Schechter Andrew
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