Liquid crystal cells – elements and systems – Particular structure – Having significant detail of cell structure only
Reexamination Certificate
2003-05-23
2004-01-06
Niebling, John F. (Department: 2812)
Liquid crystal cells, elements and systems
Particular structure
Having significant detail of cell structure only
C438S145000
Reexamination Certificate
active
06674501
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to a pixel unit, and more particularly to a pixel unit included in a multi-domain vertically aligned liquid crystal display.
BACKGROUND OF THE INVENTION
The current trend is towards liquid crystal displays for achieving a larger panel size and a higher resolution. However, the characteristics of response time and wide-viewing angles of a liquid crystal display are still needed to be improved.
In order to improve the response time and the wide-viewing angles, a multi-domain vertically aligned (MVA) liquid crystal display is developed as shown in FIGS.
1
(
a
) and (
b
). Liquid crystal molecules
13
around protrusions
12
which are formed on an upper substrate
10
and a lower substrate
11
are aligned with an advance inclination as shown in FIG.
1
(
a
) by the protrusions
12
. Therefore, when the liquid crystal molecules
13
are applied with an electric field, the liquid crystal molecules
13
are in the inclination state, so that the response time and the wide-viewing angle are improved.
Please refer to FIGS.
2
(
a
) and (
b
) showing another type of a multi-domain vertically aligned liquid crystal display. The protrusion
22
is only formed on the upper substrate
20
, and the lower substrate
21
has corresponding slits
23
thereon. Therefore, the liquid crystal molecules
24
are aligned as those in
FIG. 1
, and the response time and the wide-viewing angle of the multi-domain vertically aligned liquid crystal display are improved.
The fabricating processes of the foresaid multi-domain vertically aligned liquid crystal display are complex, so that a cruciform bump structure
31
formed around a pixel electrode
30
as shown in
FIG. 3
is developed. The fabricating process is easier, and the four regions having different alignments of the liquid crystal molecules are formed. However, disclination lines are generated at some positions around the pixel electrode, and the transmittance of the panel of the liquid crystal display are decreased.
The present invention provides a pixel unit for being used in a multi-domain vertically aligned liquid crystal display to overcome the foresaid drawbacks.
SUMMARY OF THE INVENTION
It is an object of the present invention to provide a pixel unit included in a multi-domain vertically aligned liquid crystal display.
In accordance with present invention, the pixel unit includes a first insulating substrate, a second insulating substrate, a plurality of liquid crystal molecules, an electric field generation device, and a cone protrusion.
The first insulating substrate has a first side and a second side.
The second insulating substrate has a third side and a fourth side.
A plurality of liquid crystal molecules are filled between the first side of the first insulating substrate and the fourth side of the second insulating substrate.
The electric field generation device provides an electric field to change alignment of the liquid crystal molecules.
The cone protrusion is formed on the first side of the first insulating substrate for generating an advance inclination of the liquid crystal molecules around the cone protrusion.
Preferably, the first substrate and the second substrate are substrates pervious to light.
Preferably, the substrates are glass substrates.
In addition, the electric field generation device includes a pixel electrode formed on the fourth side of the second insulating substrate, and a common electrode formed on the first side of the first insulating substrate.
Preferably, the cone protrusion is disposed above a center of the pixel electrode.
It is another object of the present invention to provide a method for fabricating a cone protrusion in a fabricating process of a liquid crystal display.
In accordance with the present invention, the method includes steps of providing an insulating substrate, forming a positive photoresist layer on the insulating substrate, performing an exposure on the positive photoresist layer by using a mask, wherein a masking region of the mask is a pattern having a masking rate decreased progressively from center to surrounding, and performing a development to remove the positive photoresist layer and form a cone protrusion on the insulating substrate.
Preferably, the insulating substrate is a substrate pervious to light.
Preferably, the substrate is a glass substrate.
Preferably, the masking region is circle-shaped.
Preferably, the liquid crystal display is a multi-domain vertically aligned liquid crystal display.
It is another object of the present invention to provide a method for fabricating a cone protrusion in a fabricating process of a liquid crystal display.
In accordance with the present invention, the method includes steps of providing an insulating substrate, forming a negative photoresist layer on the insulating substrate, performing an exposure on the negative photoresist layer by using a mask, wherein a masking region of the mask is a pattern having a masking rate decreased progressively from center to surrounding, and performing a development to remove the negative photoresist layer and form a cone protrusion on the insulating substrate.
Preferably, the insulating substrate is a substrate pervious to light.
Preferably, the substrate is a glass substrate.
Preferably, the masking region is circle-shaped.
Preferably, the liquid crystal display is a multi-domain vertically aligned liquid crystal display.
REFERENCES:
patent: 6285123 (2001-09-01), Yamada et al.
patent: 6369870 (2002-04-01), Koma
patent: 6410368 (2002-06-01), Kawasaki et al.
patent: 6452573 (2002-09-01), Martinot-Lagarde et al.
patent: 6456349 (2002-09-01), Hanyu et al.
patent: 6471903 (2002-10-01), Sherman et al.
patent: 6483643 (2002-11-01), Zuchowski
patent: 6501526 (2002-12-01), Oh
Tanaka Sakae
Wu Long-Hai
Klein O'Neill & Singh, LLP
Luk Olivia
Niebling John F.
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