Liquid crystal cells – elements and systems – Nominal manufacturing methods or post manufacturing... – Sealing of liquid crystal
Reexamination Certificate
2002-10-07
2004-05-25
Ton, Toan (Department: 2871)
Liquid crystal cells, elements and systems
Nominal manufacturing methods or post manufacturing...
Sealing of liquid crystal
C349S153000, C349S187000
Reexamination Certificate
active
06741322
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a production line for manufacturing a liquid crystal display (LCD) device, and more particularly, to a production line of an LCD device based on a liquid crystal dispensing method.
2. Discussion of the Related Art
Generally, ultra thin sized flat panel displays having a display screen with a thickness of several centimeters or less, and in particular, flat panel LCD devices, are widely used in monitors for notebook computers, spacecraft, and aircraft because such LCD devices have low power consumption because of a low driving voltage and are easy to carry.
Such LCD devices include a lower substrate, an upper substrate and a liquid crystal layer. A thin film transistor (TFT) and a pixel electrode are formed on the lower substrate. A light-shielding layer, a color filter layer and a common electrode are formed on the upper substrate, which is opposite to the lower substrate. Then, the liquid crystal layer is formed between the lower and upper substrates. In operation, an electric field is generated between the lower and upper substrates by the pixel and common electrodes, so that the alignment of molecules in the liquid crystal layer is driven by the electric field. Transmissivity of light through the liquid crystal layer is controlled with driving the liquid crystal layer, thereby displaying an image.
In manufacturing this LCD device, a vacuum injection method based on capillary phenomenon and pressure difference has been conventionally used to form the liquid crystal layer between lower and upper substrates. However, such a vacuum injection method has a problem in that it takes a long time to inject the liquid crystal due to the large sized display area, thereby reducing the productivity.
A liquid crystal dispensing method has been proposed to solve such a problem. A prior art method for manufacturing an LCD device based on the liquid crystal dispensing method will be explained with reference to
FIG. 1A
to FIG.
1
D.
As illustrated in
FIG. 1A
, a lower substrate
1
and an upper substrate
3
are prepared. Although not shown in drawings, a plurality of gate and data lines are formed on the lower substrate
1
. The gate lines cross the data lines to define pixel regions. A thin film transistor (TFT) is formed at each crossing point between the gate and data lines. A pixel electrode connected with the thin film transistor is formed in the pixel region.
A light-shielding layer is formed on the upper substrate
3
to prevent light from leaking out from the gate and data lines and the thin film transistor. Color filter layers of red(R), green(G), and blue(B) are formed on the light-shielding layer, and a common electrode is formed on the color filter layers. An alignment layer is formed on at least one of the lower substrate
1
and the upper substrate
3
to initially align molecules in a liquid crystal to be interposed between the upper and lower substrates
1
and
3
.
As shown in
FIG. 1B
, a sealant
7
is formed on the lower substrate
1
and a liquid crystal
5
is dropped thereon, so that a liquid crystal layer is formed. A spacer (not shown) is spread onto the upper substrate
3
to maintain a cell gap between the upper and lower substrates
1
and
3
.
In manufacturing an LCD device according to the vacuum injection method, the liquid crystal is injected between the substrates after bonding the substrates to each other. However, in manufacturing an LCD device according to the liquid crystal dispensing method, the lower and upper substrates
1
,
3
are bonded to each other after dispensing the liquid crystal
5
onto the substrates. Therefore, if a heat-hardening sealant is used as the sealant
7
in the LCD device according to the liquid crystal dispensing method, the sealant
7
may flow out of the substrate when it is heated. For this reason, a problem arises in that the liquid crystal
5
is contaminated. Accordingly, in the method of manufacturing the LCD based on the liquid crystal dispensing method, a UV-hardening sealant is used as the sealant
7
instead of a heat-hardening sealant.
Referring to
FIG. 1C
, the lower substrate
1
is attached to the upper substrate
3
.
Referring to
FIG. 1D
, UV light is irradiated from a UV irradiating device
9
so that the sealant
7
is hardened, thereby bonding the lower substrate
1
and the upper substrate
3
to each other.
In manufacturing the LCD device based on the liquid crystal dispensing method, after attaching the lower substrate to the upper substrate, the sealant
7
formed on the lower substrate
1
is hardened in a UV irradiating process and the lower substrate
1
is bonded to the upper substrate
3
. Accordingly, if the sealant formed on the lower substrate
1
is hardened before attaching the lower and upper substrates to each other, the lower substrate
1
is not bonded to the upper substrate
3
perfectly.
A production line of the LCD device based on the prior art liquid crystal dispensing method will be explained as follows.
First, the lower substrate having the TFT and the pixel electrode is loaded to a first loading device and then is moved to a sealant forming device and a liquid crystal dispensing device. Then the sealant and the liquid crystal layer are formed on the lower substrate. The upper substrate having the light-shielding layer, the color filter layer and the common electrode is loaded to a second loading device and is moved to a spacer scattering device, thereby forming a spacer on the upper substrate. The lower and upper substrates are moved to an attaching device and are attached to each other. After that, the attached substrates are moved to the UV irradiating device to harden the sealant, thereby bonding the lower and upper substrates to each other.
At this time, a cover is provided to an upper space of each device and a line between the devices. The cover is made of a transparent material for being watched by an operator. The top of the cover is opened so that dust generated during manufacturing the LCD device are discharged through the top of the cover. Also, a lamp is provided above the devices for manufacturing the LCD. If UV light is irradiated on the substrates through the cover and the upper space where the cover is not formed, the sealant may be hardened before arriving in the attaching device, so that the lower and upper substrates are not bonded perfectly.
SUMMARY OF THE INVENTION
Accordingly, the present invention is directed to a production line for manufacturing an LCD device that substantially obviates one or more problems due to limitations and disadvantages of the related art.
An advantage of the present invention is to provide a production line for the manufacture of an LCD device, in which a sealant is not hardened until arriving in an attaching device.
Additional advantages 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 or may be learned from practice of the invention. These and other advantages of the invention may be realized and attained by the structure 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 invention, as embodied and broadly described herein, a production line of an LCD device according to the preferred embodiments of the present invention includes a production line shield being formed of a UV blocking material and positioned along a sealant forming device and an attaching device and between the sealant forming device and the attaching device; and at least one work lamp that irradiates light in a band other than an ultraviolet band.
If the work lamp is provided in the entire production line, the aforementioned problem is not generated. However, it has a problem in that an operator cannot watch process steps of a production line since the brightness of the work lamp is low.
Accordingly,
Byun Yong Sang
Jung Sung Su
Park Moo Yeol
LG. Philips LCD Co. Ltd.
McKenna Long & Aldridge LLP
Schechter Andrew
Ton Toan
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