Liquid crystal cells – elements and systems – Particular structure – Having significant detail of cell structure only
Reexamination Certificate
1998-12-18
2001-12-04
Sikes, William L. (Department: 2871)
Liquid crystal cells, elements and systems
Particular structure
Having significant detail of cell structure only
C349S124000
Reexamination Certificate
active
06327012
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to a method for manufacturing a liquid crystal display (referred to as LCD hereinafter), and more particularly to an LCD manufacturing method capable of obtaining an LCD having high display grade and high reliability.
An orientation film for performing alignment control of liquid crystal material in the LCD is formed so as to cover not only a display area on an electrode substrate but also a seal-forming area outside the display area. However, the orientation film is not formed on external connection terminals in order to connect with connecting terminals of peripheral parts which constitutes part of the LCD.
When a surface of the orientation film on the electrode substrate is processed by a rubbing method, the external connection terminals are directly subject to friction by a rubbing cloth. This leads to a problem that the external connection terminals are prone to becoming damaged and dirtied by foreign matters and thereby conduction failures might occur when electrically connected to the connecting terminals of the peripheral parts. Further, there is a difference in level between one region where the orientation film is formed and the other region where the orientation film is not formed. Therefore, the difference in level allows pile (fine threads) of the rubbing cloth to be disordered at the time of rubbing. This leads to another problem, non-uniformity on the orientation film that appears in the display area and deteriorates the display grade when the disorder of the pile is transferred to the orientation film.
As measures for solving these problems, there has been proposed a method, as disclosed in Japanese Patent Laid-open Publication Nos. HEI 5-11250 and HEI 7-301776, in which after forming an orientation film as a protective film on the external connection terminals and then performing the orientation process to the surface of the orientation film by the rubbing method, the orientation film is removed by plasma etching so that the external connection terminals are electrically connected to terminals of peripheral parts.
However, since the orientation film is removed by plasma etching, the equipment for plasma etching is large in scale. Also disadvantages in processing capacity and equipment investment are incurred and a problem of high cost arises.
Meanwhile, there has recently been proposed a method for removing the orientation film in which molecular bonds of the orientation film are decomposed and sublimated by using a mercury ultraviolet lamp. With reference to
FIG. 3
, numeral
20
denotes an ultraviolet beam
20
from a mercury ultraviolet lamp and numeral
21
denotes an electrode substrate. Numerals
22
a
and
22
b
denote a display electrode and external connection terminals continuous from the display electrode, respectively. The display electrode
22
a
and the external connection terminals
22
b
are formed from a transparent electrically conducting film. Numerals
23
and
24
denote a transparent insulating film and an orientation film, respectively. Also, numeral
25
denotes a mask which has openings so as to be open above regions of the orientation film
24
overlying the external connection terminals
22
b.
After the mask
25
is placed above the electrode substrate
21
, the orientation film
24
on the external connection terminals
22
b
is irradiated via the mask
25
with the ultraviolet beam
20
from the mercury ultraviolet lamp. Thereby the orientation film
24
on the external connection terminals
22
b
is removed.
However, in the above method for removing the orientation film
24
, it is impossible to accurately control the irradiation range of the ultraviolet beam
20
from the mercury ultraviolet lamp. This is because the ultraviolet beam
20
does not have sufficient directivity. Accordingly, the mask
25
should be used and there arises a problem that production efficiency of the LCD is lowered since it is necessary to add a process of placing the mask
25
.
Also, it is difficult to concentrate light intensities of the mercury ultraviolet lamp to the wavelength range in which molecular bonds of the orientation film
24
are decomposed and sublimated. As a result, the electrodes
22
a
of the transparent conducting film, the insulating film
23
, a color filter and other members located near the orientation film
24
that is to be removed are adversely affected, involving faulty phenomena such as deformation due to temperature increases, deterioration of strength, deterioration of coloring and transparency caused by photochemical changes.
SUMMARY OF THE INVENTION
The object of the present invention is to provide a method for manufacturing an LCD in which an LCD that is superior in display grade and higher, in reliability is obtained without the above problems of the prior art.
In order to achieve the above-mentioned object, the present invention provides a method for manufacturing a liquid crystal display, comprising the steps of:
forming an orientation film over an entire electrode substrate, said electrode substrate having external connection terminals at a peripheral portion thereof;
processing a surface of the orientation film by a rubbing method; and
irradiating the orientation film on the external connection terminals with an ultraviolet laser beam so as to remove the orientation film from the external connection terminals.
In an embodiment of the invention, energy density of the ultraviolet laser beam is adjusted with an attenuator.
In an embodiment of the invention, energy density of the ultraviolet laser beam is within a range of 110 to 210 mJ/cm
2
.
REFERENCES:
patent: 5691792 (1997-11-01), Mizushima et al.
patent: 5705096 (1998-01-01), Kano et al.
patent: 5770826 (1998-06-01), Chaudhari et al.
patent: 5817743 (1998-10-01), Gibbons et al.
patent: 5854803 (1998-12-01), Yamazaki et al.
patent: 5855968 (1999-01-01), Hirata et al.
patent: 5965691 (1999-10-01), Gibbons et al.
patent: 6099786 (2000-08-01), Hu et al.
patent: 05011250A (1993-01-01), None
patent: 07301776A (1995-11-01), None
patent: 10104625A (1998-04-01), None
Conlin David G.
Daley, Jr. William J.
Dike Bronstein Roberts & Cushman
Nguyen Dung
Sharp Kabushiki Kaisha
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