Radiation imagery chemistry: process – composition – or product th – Imaging affecting physical property of radiation sensitive... – Making named article
Reexamination Certificate
2000-10-12
2002-11-12
McPherson, John A. (Department: 1756)
Radiation imagery chemistry: process, composition, or product th
Imaging affecting physical property of radiation sensitive...
Making named article
C430S396000, C349S124000, C349S129000
Reexamination Certificate
active
06479218
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a method or manufacturing a multi-domain liquid crystal cell, and more particularly, to a method for manufacturing a multi-domain liquid crystal cell in which a liquid crystal cell of a multi-domain liquid crystal cell having a wider viewing angle is obtained by a simple process.
2. Discussion of the Related Art
Recently, a liquid crystal display (LCD) mainly used for portable televisions or notebook computers requires a large sized screen, so as to be used for a wall type television or a monitor. A twisted-nematic (TN) liquid crystal cell is generally used as an LCD. The TN liquid crystal cell has different optical transmittivity characteristics at each gray level depending on viewing angles. For this reason, a large area of the TN liquid crystal cell is limited. That is, optical transmittivity is substantially symmetrical in view of a viewing angle in left and right direction while optical transmittivity is asymmetrical in view of us and down direction. Accordingly, an image inversion area exists in the viewing angle in up and down direction. As a result, there is a problem that the viewing angle becomes narrow. To solve such a problem, there is suggested a multi-domain liquid crystal cell in which a compensation effect of a viewing angle is obtained by varying a main viewing angle in each pixel. To obtain the multi-domain liquid crystal cell, a reverse rubbing process will be described with reference to FIG.
1
.
As shown in
FIG. 1
a
, an entire substrate
11
on which a polyimide
12
is deposited is processed by rubbing. Thus, a mono-domain is formed as shown in
FIG. 1
b
. As shown in
FIG. 1
c
, one domain is blocked by a photoresist
13
. Rubbing is then performed in a direction opposite to the rubbing direction of
FIG. 1
a
. As shown in
FIG. 1
d
, a domain which is not blocked by the photoresist
13
is processed by reverse rubbing. As shown in
FIG. 1
e
, if the photoresist
13
is removed, a substrate divided into two domains having opposite pretilt angles can be obtained.
However, the liquid crystal cell manufactured by the above rubbing process has problems in that dust or static electricity occurs during the rubbing process, thereby reducing yield or damaging the liquid crystal cell.
In another related art, to solve such problems, photo-alignment methods based on UV rays have been suggested instead of rubbing One photo-alignment method will be described with reference to FIG.
2
. As shown in
FIG. 2
a
, a substrate
21
on which an alignment film
22
is deposited is periodically shielded by a mask
23
having a light-transmitting portion
25
and a light-shielding portion
24
. When light (solid line arrow in tilt direction on a top of the drawing) is irradiated at a tilt at an angle of &thgr;, a first pretilt is determined in a portion
26
where light is transmitted. As shown in
FIG. 2
b
, the mask
23
is rearranged to shield light in the portion
26
. Then, when light (solid line arrow in tilt direction on a top of the drawing) is irradiated at a tilt at an angle of −&thgr;, a second pretilt is determined in a portion
27
where light is shielded in
FIG. 2
a
. Thus, as shown in
FIG. 2
c
, a first substrate of two domains having different pretilts can be obtained. Also, as shown in
FIG. 2
d
, a second substrate of two domains can be obtained by the above alignment method and lower and upper substrates are assembled with each other.
Furthermore, as shown in
FIG. 3
, areas Q and R are light-shielded, and the photo-alignment methods having an angle &thgr; of irradiation in
FIGS. 2
a
and
2
b
are sequentially applied to areas O and P as shown in
FIGS. 3
a
and
3
b
. The areas O and P are then light-shielded, and the photo-alignment methods having an angle &thgr; of irradiation in
FIGS. 2
a
and
2
b
are sequentially applied to the areas Q and R as shown in
FIGS. 3
c
and
3
d
. Thus, light irradiation of total four times is performed on the substrate, thereby obtaining a substrate having four domains.
As described above, the first substrate and the second substrate in which four domains are formed are bonded to face each other and then the liquid crystal is injected thereto, so that a four-domain liquid crystal cell can be obtained.
In still another related art, as shown in
FIG. 4
a
, a semi-transparent portion
43
of a mask is arranged in some area of a substrate
41
on which an alignment film
42
is deposited, and then light irradiation is performed. Thus, the irradiated light is absorbed in the alignment film
42
on the substrate
41
in an aperture portion. However, some of the irradiated light is only absorbed in the alignment film
42
in an area of the alignment film
42
of the substrate
41
corresponding to the semi-transparent portion
43
of the mask. Polysiloxane based materials used as the alignment film
42
are characterized in that the size of tie pretilt angle becomes small as absorbing light energy increases. Accordingly, the size of the pretilt angle formed in the alignment film can easily be controlled. Based on this characteristic, a substrate having different pretilt angles and divided pixels is manufactured, and a sectional view of the substrate is shown in
FIG. 4
b
. As shown in
FIG. 4
c
, a liquid crystal cell is manufactured in such a manner that upper and lower substrates are bonded to each, other by applying the substrate of
FIG. 4
b
. In this structure, alignment direction of each domain is identical in each substrate but the size of the pretilt angle is different. Accordingly, a multi-domain is formed to improve a viewing angle. Also, in case that the divided pixels are applied, a four domain liquid crystal cell can be obtained as shown in FIG.
5
. In this case, areas III and IV are light-shielded and the photo-alignment method of
FIG. 4
a
is applied to areas I and II (see
FIGS. 5
a
to
5
d
). Subsequently, the areas I and II are light-shielded, and in the areas III and IV, a four-domain substrate is obtained by varying polarization direction of tie irradiated light in the photo-alignment method of
FIG. 4
a
(see
FIGS. 5
e
to
5
h
) . After the first and second substrates in which four domains are formed are bonded to each other by the above method, the liquid crystal is injected into the substrates so as to obtain a four-domain liquid crystal cell.
However, the methods for manufacturing a liquid crystal cell through the photo-alignment methods have several problems in controlling alignment direction of the multi-domain to realize a wider viewing angle.
The first method requires light irradiation of eight times (vertical irradiation of four times and tilt irradiation of four times) into the upper and lower substrates to form a multi-domain divided into two pixel areas, and mask bond no process of four times. Moreover, to form a multi-domain having four domains, the process steps increase two times. Thus, in addition to light irradiation and mask bonding processes of several times, a cap between the masks and the substrate should additionally be controlled. These process steps are unattractive in view of the mass production. The second method requires light irradiation of four times (vertical irradiation of two times and tilt irradiation of two times) into the upper and lower substrates and mask bonding process of two times when forming a multi-domain having two domains. In the second method, the light irradiation and the mask bonding process steps have been reduced but error may occur in arranging a number of masks, thereby reducing the productivity.
SUMMARY OF THE INVENTION
Accordingly, the present invention is directed to a method for manufacturing a multi-domain liquid crystal cell 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 manufacturing a multi-domain liquid crystal cell fin which a photo mask required for photo-alignment is improved to perform tilt irradiation having two di
LG Philips LCD Co., Ltd
McKenna Long & Aldridge LLP
McPherson John A.
LandOfFree
Method for manufacturing multi-domain liquid crystal cell does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Method for manufacturing multi-domain liquid crystal cell, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Method for manufacturing multi-domain liquid crystal cell will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2933480