Liquid crystal cells – elements and systems – Particular structure – Having significant detail of cell structure only
Reexamination Certificate
2001-01-19
2004-10-05
Parker, Kenneth (Department: 2871)
Liquid crystal cells, elements and systems
Particular structure
Having significant detail of cell structure only
C349S087000, C349S090000
Reexamination Certificate
active
06801273
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a liquid crystal display, and more particularly, to an apparatus and method for injecting a liquid crystal into a liquid crystal display panel and sealing it.
2. Discussion of the Related Art
Generally, an active matrix liquid crystal display (LCD) uses a thin film transistor (TFT) as a switching device to display a moving picture. Since the LCD can be made smaller in size than the existing cathode ray tube (CRT), it has been widely used in various applications including a display for personal computer, or a notebook computer, as well as an office automation equipment (e.g., a copy machine) and a portable equipment (e.g., a PDA or a pager).
A process of fabricating the active matrix LCD includes substrate cleaning, substrate patterning, alignment film formation, substrate adhesion/liquid crystal injection and packaging steps. In the substrate cleaning process, a foreign substance on the substrates is removed by a cleaner before and after patterning of the upper and lower substrates. The substrate patterning process is divided into a step of patterning the upper substrate and a step of patterning the lower substrate. On the upper substrate, color filters, a common electrode and black matrices, are formed. Signal wires such as data lines and gate lines are formed on the lower substrate. A thin film transistor (TFT) is formed at each intersection of the data lines and the gate lines. A pixel electrode is formed at each pixel area defined by the data lines and the gate lines and connected to a source electrode of the TFT. In the substrate adhesion/liquid crystal injection process, an alignment film is coated on the lower substrate and a rubbing step is performed which are sequentially followed by an upper/lower substrate adhesion step, liquid crystal injection step and an injection hole sealing step. Finally, in the packaging process, a tape carrier package (TCP) mounted with integrated circuits (ICs) such as a gate driver and a data driver is connected to a pad portion on the substrate.
In such an LCD fabricating method, a process of injecting a liquid crystal into the liquid crystal display panel has been performed by a liquid crystal injecting apparatus as shown in FIG.
1
.
Referring to
FIG. 1
, the conventional liquid crystal injecting apparatus includes a loader
2
loaded with cassettes, first and second pre-heaters
4
and
6
for heating a liquid crystal display panel conveyed from the loader
2
, a vacuum unit for making the interior of the liquid crystal display panel into a vacuum state, and a bubble remover
16
for removing air bubbles within the liquid crystal display panel. The loader
2
is mounted with cassettes, each of which has been vertically loaded with a liquid crystal display panel. The first pre-heater
4
activates humidity and ionized contaminants, etc. at the interior of the liquid crystal display panel and evacuates them into the exterior of the liquid crystal display panel. The second pre-heater
6
heats the liquid crystal display panel to relieve stress on the liquid crystal display panel. The vacuum unit
8
causes the space for liquid crystal injection to be in a vacuum state of 10
−6
Torr so that the liquid crystal can be injected into the interior of the liquid crystal display panel. The first injector
10
is converted from the vacuum state to the atmospheric state to primarily inject the liquid crystal into the liquid crystal injecting space. The second injector
12
secondarily injects the liquid crystal into the liquid crystal injecting space in the atmospheric state. The unloader
14
is loaded with the cassettes, each of which is mounted with the liquid crystal display panel into which a liquid crystal has been injected.
In operation, the liquid crystal display panel as discussed above is vertically loaded in the cassette such that the liquid crystal injection hole points downward to be mounted onto the loader
2
. The cassette mounted onto the loader
2
is conveyed to the first pre-heater
4
by means of a conveyor (not shown). The first pre-heater
4
heats the liquid crystal display panel to a desired temperature to activate humidity and ionized contaminants at the interior of the liquid crystal display panel, thereby forcing them to the exterior of the liquid crystal display panel. The liquid crystal display panel heated at the first pre-heater
4
is conveyed to the second pre-heater
6
. The second pre-heater
6
heats the liquid crystal display panel at a desired temperature to relieve stress on the liquid crystal display panel. The liquid crystal display panel heated at the second pre-heater
6
is conveyed to the vacuum unit
8
. The vacuum unit
8
cuases the liquid crystal injecting space to be in a vacuum state so that liquid crystal can be injected into the interior space of the liquid crystal display panel. The liquid crystal display panel, in the vacuum state, is moved into the first injector
10
. Thereafter, the first injector
10
receives nitrogen from a nitrogen supplier (not shown) to convert the LCD panel from the vacuum state to the atmospheric state. At this time, the liquid crystal in which air bubbles are removed is primarily injected from the bubble remover
16
by a pressure difference between the liquid crystal injecting space and the first injector
10
. Thereafter, the liquid crystal display panel is moved into the second injector
12
. The second injector
12
secondarily injects the liquid crystal into the liquid crystal display panel while maintaining the atmospheric state. By this procedure, a desired number of liquid crystal display panels loaded in the cassette is injected. The liquid crystal display panels into which liquid crystal has been injected are moved into the unloader
14
. The liquid crystal display panels moved into the unloader
14
are conveyed into a liquid crystal sealing apparatus to seal the liquid crystal injection hole.
FIG. 2
is a block diagram showing a configuration of a conventional sealing apparatus employing a dispenser system. Referring to
FIG. 2
, the conventional sealing apparatus of the dispenser system includes a loader
18
mounted with a cassette loaded with a desired number of liquid crystal display panels, first and second inverters for inverting the liquid crystal display panels conveyed from the loader
18
, a residual liquid crystal remover
23
for removing contaminated liquid crystal at the periphery of a liquid crystal injection hole in a liquid crystal injection process, a sealer
24
for sealing the liquid crystal injection hole, an ultraviolet irradiating unit
25
for hardening a sealant sealed at the sealer
24
, a third inverter
26
for inverting the liquid crystal display panels, and an unloader
28
mounted with the cassette. The liquid crystal display panel into which a liquid crystal panel has been injected by the liquid crystal injecting apparatus is vertically loaded in the cassette to be mounted into the loader
18
. Each of the first and second inverters
20
and
22
rotates the liquid crystal display panel by 90° in the same direction to make a total rotation of 180°. The residual liquid crystal remover
23
jets nitrogen at a high pressure to remove liquid crystal formed at the liquid crystal injection hole. The sealer
24
seals the liquid crystal injection hole using a sealant. The ultraviolet irradiating unit
25
irradiates an ultraviolet ray to harden the sealant. The third inverter
26
rotates the liquid crystal display panel by 90°. The unloader
28
is mounted with a cassette which is loaded with the liquid crystal display panel in which the liquid crystal sealing process has been finished.
In operation, the liquid crystal display panel into which liquid crystal has been injected is vertically loaded in the cassette such that the liquid crystal injection hole points downward to be mounted onto the loader
18
. The cassette mounted onto the loader
18
is conveyed to the first inverter
20
by means of a conveyor (not shown). The first inv
Lee Sang Mun
Ryu Joung Ho
LG. Philips LCD Co. Ltd.
McKenna Long & Aldridge LLP
Parker Kenneth
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