Apparatus and method of manufacturing liquid crystal display

Liquid crystal cells – elements and systems – Liquid crystal system

Reexamination Certificate

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Details

C349S158000, C349S153000

Reexamination Certificate

active

06646689

ABSTRACT:

BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an apparatus and a method of manufacturing a liquid crystal display by bonding two transparent substrates in a vacuum, and particularly, to an apparatus and a method of manufacturing a liquid crystal display, which makes it possible to easily perform an alignment with high precision in a short time.
2. Description of the Related Art
Conventionally, as a method of manufacturing a liquid crystal display, there has been a method having the steps of forming a sealing material between two substrates and injecting a liquid crystal into the inside thereof as described below. Hereinafter, this manufacturing method is referred to as “a first prior art”.
FIG. 1
is a flowchart showing the method of manufacturing a liquid crystal display according to the first prior art.
First, two substrates are provided. On one surface of one substrate, a thin film transistor (TFT) is formed in an array shape. Hereinafter, this substrate is referred to as “a TFT substrate”. On one surface of the other substrate, a color filter (CF) is formed. Hereinafter, this substrate is referred to as “a CF substrate”. Thereafter, an orientation film is formed on both the TFT substrate and the CF substrate (step S
1
). Next, spacers are formed on the surface of the CF substrate on which the CF is formed (step S
2
a
), and a sealing material having an injection hole in part is formed in a rectangular shape on the surface of the first substrate (the TFT substrate) on which the TFT is formed (step S
2
b
). Thereafter, the surfaces of the second substrate (the CF substrate) and the first substrate on which the CF and the TFT are respectively formed are opposed to each other, and then superposed one on another (step S
3
). Subsequently, these are heated so that the sealing material formed in the first substrate is burned (step S
4
).
Thereafter, the superposed first and second substrates are cut and divided into the predetermined number of panels (step S
5
). Then, a liquid crystal is injected into the inside through the injection hole provided in the sealing material (step S
6
). Thereafter, the injection hole is sealed (step S
7
). And then, a cleaning of the panel is performed in order to eliminate contamination made by the liquid crystal injection and the like (step S
8
). Thereafter, a polarizing plate is attached thereon, and a driving circuit and the like are installed, thereby a liquid crystal display is completed.
However, in the first prior art, there is a problem that there are too many steps.
Therefore, recently, in the standpoint of reducing the number of steps, a manufacturing method having the steps of dropping a liquid crystal in a TFT substrate and bonding the TFT substrate and a CF substrate in a vacuum has been developed and known. Hereinafter, this manufacturing method is referred to as “a second prior art”.
FIG. 2
is a flowchart showing the method of manufacturing a liquid crystal display according to the second prior art.
First, as in the first prior art, two substrates are provided. After that, an orientation film is formed on both a first substrate (a TFT substrate) and a second substrate (a CF substrate) (step S
11
). Next, spacers are formed on the surface of the second substrate on which the CF is formed (step S
12
a
), and a sealing material composed of a photo-curable resin is formed in a rectangular shape on the surface of the first substrate on which the TFT is formed (step S
12
b
). Thereafter, a liquid crystal is dropped inside of the sealing material in the first substrate, and the surfaces of the second substrate and the first substrate on which the CF and the TFT are respectively formed are opposed in a vacuum and aligned, and pressed each other, and then the vacuum is ventilated (released to the atmosphere), so that the second substrate and the first substrate are fixed by an atmospheric press (step S
13
).
Next, the sealing material is irradiated by ultraviolet rays to become a semi-cured state (step S
14
). Subsequently, the sealing material is heated to be thermally cured (step S
15
). Then, the bonded first and second substrates are cut and divided into the predetermined number of panels (step S
16
). Thereafter, a polarizing plate is attached thereon, and a driving circuit and the like are installed, thereby a liquid crystal display is completed.
FIG. 3
is a cross sectional view showing the structure of an apparatus for manufacturing a liquid crystal display used in the second prior art.
In the conventional apparatus for manufacturing a liquid crystal display, there is provided with a vacuum chamber
111
, and a first surface plate
112
and a second surface plate
113
are provided within the vacuum chamber
111
in parallel to each other. In the vacuum chamber
111
, there are provided with a vacuum suction opening
111
a
and a vacuum exhaust opening
111
b
. The material for the first surface plate
112
is, for example, ceramics, and an electrode (the first substrate sucker)
114
for electrostatic suction of a first substrate
131
is padded in the surface opposite to the second surface plate
113
. Likewise, the material for the second surface plate
113
is, for example, ceramics, and an electrode (the second substrate sucker)
115
for electrostatic suction of a second substrate
132
is padded in the surface opposite to the first surface plate
112
. Also, in each of the first surface plate
112
and the second surface plate
113
, inhalation holes (not shown) and the like for vacuum suction of the first substrate
131
and the second substrate
132
are provided.
Furthermore, the lower surface of the first surface plate
112
is connected to the upper end of a first surface plate-connecting pedestal
125
, and the lower end of the first surface plate-connecting pedestal
125
is connected to a position-adjusting table
126
. On the position-adjusting table
126
, there is provided with a motor (not shown), which enables the first surface plate-connecting pedestal
125
to move straight in two directions perpendicular to each other (X direction and Y direction) and to rotate in a circumferential direction (&thgr; direction) having the central axis as a rotating axis. Therefore, the position of the first surface plate
112
and the first substrate
131
is adjusted by the position-adjusting table
126
.
Further, there is provided with a pressing motor
127
, which moves the second surface plate
113
in a vertical direction to press the second surface plate
113
and the first surface plate
112
each other. The pressing motor
127
is fixed to a fixing member
128
a
. Also, outside of the vacuum chamber
111
, there are provided with an alignment camera
130
for detecting positions of alignment marks
133
and
134
respectively provided in the first substrate
131
and the second substrate
132
, and an ultraviolet rays source
135
irradiating ultraviolet rays to a photo-curable resin
143
for tacking applied between the substrates Also, a second surface plate-supporting member
129
, which supports the second surface plate
113
against the first surface plate
112
in parallel, is supported to a fixing member
128
b.
In addition, in the second prior art, although the CF substrate and the TFT substrate are pressed with superposed state in a vacuum, an alignment between the second substrate
132
(the CF substrate) and the first substrate
131
(the TFT substrate) is performed before being pressed. At this time, the gap between the second substrate and the first substrate is from about 0.2 to 0.5 mm. Further, the gap between the CF substrate and the TFT substrate, after being pressed by atmosphere (referred to as “an atmospheric press”), is about 5 &mgr;m.
According to the second prior art, in comparison to the first prior art, there are advantages that the number of steps can be reduced, and because there is no process step of injecting a liquid crystal followed by superposing the substrates, the contamination therefrom can be prevented, and the material for sealing a hole

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