Liquid crystal cells – elements and systems – Particular structure – Having significant detail of cell structure only
Reexamination Certificate
1997-02-28
2001-03-06
Sikes, William L. (Department: 2871)
Liquid crystal cells, elements and systems
Particular structure
Having significant detail of cell structure only
C349S139000, C349S150000, C349S151000, C349S152000, C349S153000, C250S559070, C029S830000
Reexamination Certificate
active
06198519
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to the field of displays and more particularly to liquid crystal displays.
BACKGROUND OF THE INVENTION
A conventional method for bonding out lead bonding (OLB) pads and tape carrier package (TCP) pads is described below with reference to
FIGS. 1 and 2
. The dummy pad groups
10
and the data/gate pad group
20
are formed on a liquid crystal display (LCD) panel
100
as shown in FIG.
1
. The dummy pad groups
10
are formed on both sides of data/gate pad group
20
. Generally, each of the pads in groups
10
and
20
includes a metal pad
12
and a layer of indium tin oxide (ITO)
13
formed on one end portion of the respective metal pad
12
. The dummy pad group also includes ITO dummy pads
30
, wherein each of the ITO dummy pads includes only a layer of ITO.
Each of the ITO layers
13
and the ITO dummy pads
30
in each pad group
10
or
20
correspond to a respective TCP OLB pad
40
, and are bonded by an anisotropic conductive layer (ACL)
50
therebetween, as shown in FIG.
2
. The ITO layers
13
enable the pad groups
10
and
20
to be bonded with the TCP OLB pads
40
, and the ITO dummy pads
30
enable the misalignment of the pads to be tested as the pads are bonded on the basis of the ITO dummy pad
30
.
It may be difficult to test misalignment of the ITO dummy pad
30
, however, because the ITO layer is transparent. In addition, measurement of any misalignment may be difficult because the pad pitch can become fine gradually. Accordingly, there continues to exist a need in the art for improved alignment tests which will allow increased productivity and reduced cost.
SUMMARY OF THE INVENTION
It is therefor an object of the present invention to provide improved liquid crystal displays and related methods.
It is another object of the present invention to provide liquid crystal displays having improved alignment and related methods.
These and other objects are provided according to the present invention by a liquid crystal display comprising a liquid crystal display panel. In addition, a dummy pad is provided on the face of the liquid crystal display panel wherein the dummy pad includes an alignment pattern therein. Accordingly, the alignment pattern can be used to determine any misalignment between the liquid crystal display panel and a bonding pad of a tape carrier package. In particular, the alignment pattern can be a vernier pattern or a saw tooth pattern. The liquid crystal display can also include a data/gate pad on the face of the liquid crystal display panel wherein the data/gate pad includes a metal layer.
The liquid crystal display can also include a tape carrier package layer adjacent the data pad and the dummy pad opposite the face of the liquid crystal display panel, and an out lead bonding pad on the tape carrier package layer adjacent the alignment pattern of the dummy pad wherein the alignment pattern indicates an alignment of the out lead bonding pad relative to the dummy pad. As discussed above, the alignment pattern can be used to determine misalignment between the liquid crystal display panel and the tape carrier package which can be bonded together. In particular, the liquid crystal display panel and the tape carrier package can be bonded by an anisotropic conductive material therebetween.
The dummy pad can include a layer of a transparent conductive material on the alignment pattern, and the alignment pattern can be a layer of a metal with the alignment pattern therein. This metal can be chromium or tantalum, and the dummy pad can include a layer of indium tin oxide on the alignment pattern.
According to an alternate aspect of the present invention, a method for forming a liquid crystal display is provided. This method includes the step of forming a data pad on a face of a liquid crystal display panel wherein the data pad includes a first metal layer. In addition, a dummy pad is formed on the face of the liquid crystal display panel wherein the dummy pad includes an alignment pattern therein.
According to the displays and methods of the present invention, misalignment between a liquid crystal display panel and a tape carrier package can be accurately determined. Furthermore, misalignment can thus be reduced.
REFERENCES:
patent: 5317438 (1994-05-01), Suzuki et al.
patent: 5434429 (1995-07-01), Dillen et al.
patent: 5526563 (1996-06-01), Tamaki et al.
patent: 5576869 (1996-11-01), Yoshida
patent: 5657104 (1997-08-01), Kanezawa
patent: 5822030 (1998-10-01), Uchiyama
patent: 5982468 (1999-11-01), Satou et al.
patent: 6052172 (2000-04-01), Kajiwara et al.
Myers Bigel & Sibley & Sajovec
Ngo Julie
Samsung Electronics Co,. Ltd.
Sikes William L.
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