Liquid crystal cells – elements and systems – Particular structure – Having significant detail of cell structure only
Reexamination Certificate
2001-10-11
2003-04-22
Kim, Robert H. (Department: 2871)
Liquid crystal cells, elements and systems
Particular structure
Having significant detail of cell structure only
C349S187000
Reexamination Certificate
active
06552769
ABSTRACT:
This application claims the benefit of Korean Applications No. P2000-0060042, filed in Korea on Oct. 12, 2000, 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) panel, and more particularly, to a method for fabricating a liquid crystal display panel.
2. Discussion of the Related Art
A rapid development in the information and communication field has caused an increasing demand for thin, lightweight and low cost display devices for displaying information. Display development industries are responding to this need by placing high emphasis on development of flat panel type displays.
Historically, the Cathode Ray Tube (CRT) has been widely used in application for display devices, such as televisions, computer monitors, and the like. This is because CRT screens can display various colors with high brightness. However, the CRT cannot adequately satisfy the present demand for display applications that require a reduced volume/weight, improved portability, and lower power consumption as well as a large screen size and high resolution. To respond to this need, the display industry has placed high emphasis on developing flat panel displays to replace the CRT. Over the recent years, flat panel displays have found wide use in monitors for computers, spacecraft, and aircraft, etc.
Examples of flat panel display types currently used include the LCD, the electroluminescent display (ELD), the field emission display (FED), and the plasma display panel (PDP).
Characteristics required for an ideal flat panel display include a light weight, high luminance, high efficiency, high resolution, high speed response time, low driving voltage, low power consumption, low cost, and natural color.
In forming an LCD device, a sealant is applied to a first substrate that has a color filter, and the sealant is used as a sealing material at a later time. A spacer is dispersed on a second substrate having electrodes to define a proper cell gap with respect to the first substrate having the color filter. Then, the two glass substrates are attached to each other by using the sealant, and a liquid crystal is inserted therebetween.
To inject the liquid crystal, the cell defined by the two substrates is vacuumed, and the liquid crystal is inserted into the cell by utilizing a pressure difference. Thus, the liquid crystal is dispersed under a reduced pressure condition.
In more detail, the liquid crystal is injected between first and second substrates of the panel utilizing a pressure difference created by a vacuum chamber, as follows. First, the liquid crystal display panel with the sealant is located in the vacuum chamber, and the pressure is gradually reduced so that the interior of the liquid crystal display panel assumes a low pressure state close to the vacuum pressure. Then, while the interior of the liquid crystal display panel is maintained at the low pressure state, a liquid crystal injection hole is made in contact with the liquid crystal within the vacuum chamber. Then, the air is introduced into the chamber, causing the pressure at the outside of the pannel in the vacuum chamber to gradually increase. This way, a pressure difference is created between the interior and the exterior of the panel. Due to this pressure difference, the liquid crystal is injected into the interior of the panel that is in the vacuumed state. As a result, a liquid crystal layer is formed between the first and second substrates.
FIG. 1
is a sectional view of a liquid crystal display panel according to the related art. As shown in
FIG. 1
, a liquid crystal display panel includes a first substrate
11
, a second substrate
11
a,
and a sealant
13
attaching the first substrate
11
to the second substrate
11
a.
The first substrate
11
is referred to as a TFT (Thin Film Transistor) substrate, and includes pixel regions defined by mutually crossing data lines and gate lines on an active region of the first substrate
11
; a TFT at each intersection of the data lines and the gate lines, serving as a switching device; and a pixel electrode connected to a drain electrode of the TFT in a pixel region.
The second substrate
11
a
is referred to as a color filter substrate, and includes a color filter layer for displaying colors R (Red), G (Green), and B (Blue) on an active region of the second substrate
11
a;
a black matrix layer
15
for preventing light from impinging upon the TFT, data lines, and the gate lines; and an overcoat layer
17
on the entire surface of the insulating substrate including the black matrix layer
15
and a color filter layer.
Once these patterns are formed on the first and second substrates
11
and
11
a,
respectively, a spacer is dispersed on the first substrate
11
to maintain a constant gap between the first and second substrates
11
and
11
a.
A sealant
13
is applied to the peripheral of the second substrate
11
a,
and the first and second substrates
11
and
11
a
are attached to each other. A liquid crystal material is injected into the cell gap via an liquid crystal injection hole using a vacuum chamber as described above. This completes the related art method of fabricating a liquid crystal display panel.
However, in this method, a large amount of impurities and ionic materials is generated when the first and second substrates are attached to each other. These impurities and ionic materials remain in the panel, and cause stains in the panel, degrading the picture quality.
SUMMARY OF THE INVENTION
Accordingly, the present invention is directed to a method for fabricating a liquid crystal display panel that substantially obviates one or more of the problems due to limitations and disadvantages of the related art.
An object of the present invention is to provide a method for fabricating a liquid crystal display panel, which prevents generation of stains due to the liquid crystal injection process, thereby providing a liquid crystal display having an improved picture quality.
Additional advantages, objects, and features of the invention will be set forth in part in the description which follows, and in part will become apparent to those having ordinary skill in the art upon examination of the following description, or may be learned from practice of the invention.
The objectives and other advantages of the invention will be realized and attained by the scheme particularly pointed out in the written description and claims hereof as well as the appended drawings.
To achieve these and other advantages and in accordance with the purpose of the present invention, as embodied and broadly described herein, the present invention provides, in one aspect, a method for fabricating a liquid crystal display panel, including the steps of preparing a TFT substrate having a plurality of electrodes; preparing a color filter substrate having a color filter layer, a black matrix layer, and an overcoat layer; forming a groove adjacent an edge of the overcoat layer of the color filter substrate; forming a double sealant at the sides of the groove in the overcoat layer; forming a liquid crystal layer on at least one of the TFT substrate and the color filter substrate; and attaching the TFT substrate to the color filter substrate.
In another aspect, the present invention provies a method for fabricating a liquid crystal display pannel, including the steps of preparing a TFT substrate having a plurality of electrodes; preparing a color filter substrate having a color filter layer, a black matrix layer, and an overcoat layer; forming a groove adjacent an edge of the overcoat layer of the color filter substrate; forming double sealants at both sides of the groove in the overcoat layer; attaching the TFT substrate to the color filter substrate, the attached TFT substrate and the color filter substrate defining a cell; and forming a liquid crystal layer that fills the cell defined by the TFT substrate and the color filter substrate.
In the method for fabricating a liquid crystal display panel according to thes
Cho So Haeng
Chung In Jae
LG. Philips LCD Co. Ltd.
Rude T L
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