Active solid-state devices (e.g. – transistors – solid-state diode – Responsive to non-electrical signal – Electromagnetic or particle radiation
Reexamination Certificate
2002-05-22
2003-11-18
Jackson, Jerome (Department: 2815)
Active solid-state devices (e.g., transistors, solid-state diode
Responsive to non-electrical signal
Electromagnetic or particle radiation
C257S072000, C349S113000
Reexamination Certificate
active
06649992
ABSTRACT:
The present invention claims the benefit of Korean Patent Application No. 2001-28119, filed in Korea on May 22, 2001, which is hereby incorporated by reference.
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a liquid crystal display (LCD) device, and more particularly, to a transflective LCD device for a mobile communication system, using a dispensing method.
2. Description of the Related Art
In general, a liquid crystal display (LCD) device has a first substrate that includes a thin film transistor (TFT), a second substrate that includes a color filter layer, and a liquid crystal material layer interposed therebetween. Fabrication of a liquid crystal cell of the LCD device includes formation of a common electrode and a pixel electrode on opposing surfaces of the first and second substrates, respectively, and the liquid crystal material is injected through an injection hole between the first and second substrates. A polarizing plate is attached on an outer surface of each of the first and second substrates to complete the liquid crystal cell. Accordingly, image data is displayed by the LCD device by adjusting a voltage that is applied to the common and pixel electrodes to control transmittance of the liquid crystal cell.
The complete process for fabricating the liquid crystal cell includes a limited number of individual steps. In contrast, fabrication processes for forming the TFT on the first substrate and forming the color filter layer on the second substrate may be classified into a significant number of individual fabrication steps. The individual fabrication steps include processes of forming an orientation film, forming a cell gap, injecting liquid crystal material into the cell gap, and forming individual liquid crystal cells. The process for injecting liquid crystal material is performed through one of a dip method or a contact method. In the dip method, the bonded first and second substrates are dipped into a vessel containing the liquid crystal material, and a pressure difference between the bonded first and second substrates and the vessel causes injection of the liquid crystal material into the cell gap through the injection hole. In the contact method, the injection hole contacts a surface of the liquid crystal material in the vessel, and a pressure difference between the bonded first and second substrates and the vessel causes injection of the liquid crystal material into the cell gap through the injection hole. Both the dip method and the contact method are time consuming and may cause contamination of the injection hole, thereby deteriorating display quality of the LCD device.
To solve the above problems, a dispensing method is suggested wherein a sealant is printed along a boundary of an array substrate that includes a plurality of individual liquid crystal cells. Then, the liquid crystal material is dropped within a region defined by the sealant using a dispenser. Accordingly, processing time is reduced and a production yield is dramatically improved.
FIGS. 1A
to
1
C are plan views showing a fabricating process of a liquid crystal cell using a dispensing method according to the related art, and
FIGS. 1D
to
1
F are cross-sectional views of the fabrication process shown in
FIGS. 1A
to
1
C according to the related art, respectively.
In
FIGS. 1A and 1D
, a first substrate
2
includes a plurality of unit cells “A” and a second substrate
4
(in
FIGS. 1B and 1E
) includes an array line (not shown), a pixel electrode (not shown), and a switching device (not shown). A sub-color filter layer (not shown) that corresponds to the pixel electrode and a black matrix (not shown) that corresponds to a space between the pixel electrodes are formed on the first substrate
2
.
In
FIGS. 1B and 1E
, a sealant
6
is printed on the second substrate
4
corresponding to a boundary of the plurality of unit cells “A.” A liquid crystal material
8
(in
FIG. 1E
) is dropped on an inner region of the sealant
6
using a dispenser, and the first substrate
2
is attached to the second substrate
4
to form a LCD panel
10
(in FIG.
1
F).
In
FIGS. 1C and 1F
, a photo mask
12
(in
FIG. 1F
) includes a transmissive portion “B” and a blocking portion “C” that are disposed over the LCD panel
10
(in
FIG. 1F
) for hardening of the sealant
6
by exposure to ultraviolet (UV) light. The transmissive portion “B” corresponds to a position of the sealant
6
of the LCD panel
10
, and the blocking portion “C” correspond to an interior position “D” of each of the unit cells “A” (in FIG.
1
C). The interior “D” of each of the unit cells “A” provides a mask to prevent a channel region of the TFT on the second substrate
4
from being exposed to the ultraviolet light during the hardening of the sealant
6
. Then, the first and second substrates
2
and
4
are fully attached through a subsequent hot press process. Finally, the attached substrates are cut (diced) into individual unit cells “A.”
FIG. 2
is a plan view showing a second substrate of a unit cell according to the related art. In
FIG. 2
, a second substrate
20
includes a display portion “E” and a surrounding portion “F.” A plurality of array lines (not shown), a plurality of switching devices (not shown), and a plurality of pixel electrodes (not shown) are formed within the display portion “E.” A pad portion “J” is formed to extend from the plurality of array lines at the surrounding portion “F.” The pad portion “J” is formed within a region that will be covered with a case of a mobile communication system.
FIG. 3
is a magnified plan view of partial regions “G”, “H,” and “I” of
FIG. 2
according to the related art. In
FIG. 3
, a second substrate
20
includes a gate line
26
and a data line
28
. The gate line
26
includes a gate pad
24
formed within a specific area at one end of the gate line
26
. The gate line
26
crosses the data line
28
at a crossing point with an insulating layer (not shown) interposed therebetween, thereby defining a pixel region “P.” The data line
28
includes a data pad
30
formed within a specific area at one end of the data line
28
. In general, the gate pads
24
and the data pad
30
are disposed within the surrounding portion “F” of the second substrate
20
, and an external signal is applied to the gate pad
24
and the data pad
30
. A TFT “T” includes a gate electrode
32
, an active layer
34
formed on the gate electrode
32
, and a source electrode
36
and a drain electrode
38
formed on both ends of the active layer
34
. The TFT “T” is disposed adjacent to the crossing point of the gate line
26
and the data line
28
. A transflective electrode
40
is formed on the pixel region “P” and is connected to the drain electrode
38
for applying the external signal that drives a liquid crystal layer (not shown). The transflective electrode
40
defines a reflective portion “K” and a transmissive portion “L,” and includes a reflective electrode
40
a
having a transmissive hole
42
and a transmissive electrode
40
b
formed over or under the reflective electrode
40
a
with an insulating layer (not shown) interposed therebetween. A sealant (not shown) is formed at the surrounding portion “F” (of
FIG. 2
) of the array substrate
20
.
FIG. 4
is a cross-sectional view taken along IV—IV of
FIG. 3
according to the related art, and
FIG. 5
is a cross-sectional view taken along V—V of
FIG. 3
according to the related art. In
FIG. 4
, an LCD panel “M” for a mobile communication system
50
includes an attached array substrate
20
and a color filter substrate
52
, and a liquid crystal material layer
48
disposed therebetween. The LCD panel “M” may be classified into a display portion “E” and a surrounding portion “F.” A backlight
54
is disposed under the LCD panel “M” and is used for a transmissive mode of the LCD panel “M.” A case
56
covers the backlight
54
and the surrounding portion “F” of the LCD panel “M” in FIG.
5
.
As shown in
FIG. 5
, an LCD device fabricated using the dispensing method, a black matrix
58
should n
Jackson Jerome
LG. Philips LCD Co. Ltd.
Morgan & Lewis & Bockius, LLP
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