U.S. patent application number 09/994020 was filed with the patent office on 2002-05-30 for liquid crystal panel for a liquid crystal display device.
Invention is credited to Choi, Su-Seok, Choi, Suk-Won.
Application Number | 20020063838 09/994020 |
Document ID | / |
Family ID | 19702028 |
Filed Date | 2002-05-30 |
United States Patent
Application |
20020063838 |
Kind Code |
A1 |
Choi, Suk-Won ; et
al. |
May 30, 2002 |
Liquid crystal panel for a liquid crystal display device
Abstract
A liquid crystal panel for the liquid crystal display device has
a plurality of ribs disposed on an opposite internal edge to the
injection hole in order to speed up the injection time of the
liquid crystal and the ribs of the liquid crystal panel have a
shape of the teeth of a comb.
Inventors: |
Choi, Suk-Won; (Gyeonggi-do,
KR) ; Choi, Su-Seok; (Gyeonggi-do, KR) |
Correspondence
Address: |
LONG ALDRIDGE & NORMAN LLP
Suite 600
701 Pennsylvania Avenue, N.W.
Washington
DC
20004
US
|
Family ID: |
19702028 |
Appl. No.: |
09/994020 |
Filed: |
November 27, 2001 |
Current U.S.
Class: |
349/154 |
Current CPC
Class: |
G02F 1/1341
20130101 |
Class at
Publication: |
349/154 |
International
Class: |
G02F 001/1339 |
Foreign Application Data
Date |
Code |
Application Number |
Nov 28, 2000 |
KR |
2000-71352 |
Claims
What is claimed is:
1. A liquid crystal panel for a liquid crystal display device
comprises: an upper substrate having color filters and black
matrices; a lower substrate having array elements; a seal pattern
between the upper and lower substrates, the seal pattern having an
injection hole; a liquid crystal between the upper and lower
substrates; and a plurality of ribs on an internal edge facing the
injection hole.
2. The liquid crystal panel according to claim 1, wherein the ribs
are disposed in a region corresponding to black matrices.
3. The liquid crystal panel according to claim 1, wherein the ribs
include an acryl-based resin.
4. The liquid crystal panel according to claim 1, wherein the ribs
have a shape of teeth of a comb.
5. A method of injecting liquid crystal material into a liquid
crystal panel, comprising: injecting a liquid crystal material
through an injection hole into a gap formed between an upper
substrate and a lower substrate of the liquid crystal panel; and
forming a plurality of ribs within the gap opposite the injection
hole such that the liquid crystal material contacts the plurality
of ribs when more than half of the liquid crystal panel is injected
with the liquid crystal material.
6. The method of injecting liquid crystal material according to
claim 5, wherein the injection hole is formed in a seal pattern
between the upper substrate and the lower substrate.
7. The method of injecting liquid crystal material according to
claim 5, wherein the liquid crystal material is injected into the
gap through the injection hole by capillary action.
8. The method of injecting liquid crystal material according to
claim 5, wherein the liquid crystal material completely fills the
gap by capillary action of the liquid crystal material in contact
with the plurality of ribs.
9. The method of injecting liquid crystal material according to
claim 5, wherein the shape of an advancing surface of the liquid
crystal material changes from a curved shaped to a flat shape when
more than half of the liquid crystal panel is injected with the
liquid crystal material.
10. The method of injecting liquid crystal material according to
claim 5, wherein the upper substrate includes color filters and
black matrices; and the lower substrate includes array
elements.
11. The method of injecting liquid crystal material according to
claim 5, wherein the ribs are disposed on a region where the black
matrices are formed.
12. The method of injecting liquid crystal material according to
claim 5, wherein the ribs are formed of an acryl-based resin.
13. A liquid crystal panel for a liquid crystal display device,
comprising: an upper substrate; a lower substrate; a seal pattern
between the upper and lower substrates, the seal pattern having an
injection hole; a liquid crystal between the upper and lower
substrates; and a plurality of ribs on an internal edge opposite
the injection hole.
14. The liquid crystal panel according to claim 13, wherein the
ribs are disposed in a region corresponding to black matrices.
15. The liquid crystal panel according to claim 13, wherein the
ribs include an acryl-based resin.
16. The liquid crystal panel according to claim 13, wherein the
ribs have a shape of teeth of a comb.
17. A method of filling a gap in a liquid crystal panel with liquid
crystal material, comprising: injecting a liquid crystal material
into a gap formed between an upper substrate and a lower substrate
of the liquid crystal panel; and filling the gap with the liquid
crystal material using a plurality of ribs formed between the upper
substrate and the lower substrate.
Description
[0001] This application claims the benefit of Korean Patent
Application No. 2000-71352, filed on Nov. 28, 2000 in Korea, which
is hereby incorporated by reference as if fully set forth
herein.
BACKGROUND OF THE INVENTION
[0002] 1. Field of the Invention
[0003] The present invention relates to a liquid crystal display
(LCD) device and more particularly, to a liquid crystal panel
having ribs therein to reduce an injection time of liquid
crystal.
[0004] 2. Discussion of the Related Art
[0005] A typical liquid crystal display (LCD) panel has an upper
substrate and a lower substrate and a liquid crystal layer
interposed therebetween. More specifically, the upper substrate
includes common electrodes, while the lower substrate includes
switching elements, such as thin film transistors (TFTs), and pixel
electrodes.
[0006] A manufacturing process and an operation of the liquid
crystal cell will be described. Common electrodes and pixel
electrodes are formed on upper and lower substrates, respectively.
A seal is then formed on the lower substrate. The upper and lower
substrates are then bonded together using a sealing material so
that the common electrodes of the upper substrate and the pixel
electrodes of the lower substrate face each other. Thereafter,
liquid crystal panels are completed. A liquid crystal material is
injected into a gap between the upper and lower substrates through
injection holes. The injection holes are then sealed. Finally,
polarizing films are attached to outer surfaces of the upper and
lower substrates.
[0007] In operation of the liquid crystal panel, light passing
through the liquid crystal panel is controlled by electric fields.
The electric fields are applied through the pixel and common
electrodes. By controlling the electric fields, desired characters
or images are displayed on the panel.
[0008] Fabrication processes of various components of the liquid
crystal display device, such as the thin film transistors or color
filters, typically require numerous manufacturing steps. However,
the overall fabrication process for the liquid crystal display
device is relatively straightforward. FIG. 1 is a flow chart
illustrating a fabricating sequence of the liquid crystal cell for
the conventional liquid crystal display device. In the first step
(ST1), the upper and lower substrates, i.e., a color filter
substrate and an array substrate, are initially cleaned. The object
of this process is to remove impurities that may exist on the
substrate. At this time one or more cells have been already formed
on the upper and lower substrates respectively.
[0009] In the second step (ST2), alignment layers are formed on the
upper and lower substrates. The alignment layers are formed on the
common and pixel electrodes. This step includes processes for
coating an alignment layer, hardening and rubbing. A
polyimide-based resin is usually selected for an alignment layer
material because it exhibits good alignment characteristics with
various liquid crystal materials. A surface of the hardened
alignment layer is rubbed by a fabric in order to make scratches in
a uniform direction. This rubbing process is needed in order to
provide uniform alignment of the liquid crystal molecules and thus
provide a display with uniform characteristics. Accordingly, it is
very important to form the alignment layer uniformly on a large
surface of electrodes.
[0010] In the third step (ST3), a seal pattern is printed and
spacers are dispensed on the substrate. When the upper and lower
substrates are attached, the seal patterns form cell gaps that will
receive the liquid crystal material. The seal pattern also prevents
the interposed liquid crystal material from leaking out of the
completed liquid crystal cell. The seal is conventionally
fabricated using thermosetting resin including glass fiber and
screen-print technology. The seal pattern includes an injection
hole and is formed along edges of a display area of each cell.
After the seal pattern is printed, spacers are dispensed in order
to keep an accurate and uniform cell gap between the upper and
lower substrates. Accordingly, spacers have to be dispensed on
substrates with a uniform density. There are two ways for
dispensing spacers. One is a wet dispensing method which includes
spraying a mixture of alcohol and spacers, for example; and the
other is a dry dispensing method which includes spraying only
spacers.
[0011] In the fourth step (ST4), the upper and lower substrates are
aligned and attached to each other. An aligning error margin in
this case is less than a few micrometers. If the upper and lower
substrates are aligned and attached with an aligning margin larger
than the error margin discussed above, display quality of the
liquid crystal display is deteriorated due to a leakage of light
during operation of the liquid crystal cell.
[0012] In the fifth step (ST5), the liquid crystal cell fabricated
in the above steps is cut into individual liquid crystal cells. The
cutting process includes a step of scribing by which cutting lines
are formed on the substrate and a step of breaking, in which the
substrate is severed along the scribed lines.
[0013] In the sixth step (ST6), liquid crystal material is injected
into individual liquid crystal cells. Since each individual liquid
crystal cell has a gap of only a few micrometers between the
substrates per hundreds of square centimeters in area, a vacuum
injection method using a pressure difference is widely used for
injecting liquid crystal material into this liquid crystal cell. In
general, because the injection process of the liquid crystal
material into the cells takes the longest time among many
fabrication processes for the liquid crystal display device, it is
important to optimize the vacuum injection in order to increase the
fabrication yield. After the liquid crystal material is injected to
the liquid crystal cell, the injection hole needs to be sealed. The
injection hole is usually sealed by forming an ultraviolet light
curable resin on the injection hole and irradiating an ultraviolet
light to the sealed hole. Because inferior goods may be produced by
contaminations if the liquid crystal cell is exposed to the air,
the liquid crystal cell must be protected from the air and must not
be left in the air for a long time when it is not sealed.
[0014] After the injection and sealing process, the liquid crystal
cell undergoes inspection and grinding processes. In the inspection
process, the existence of contaminations in the liquid crystal
cell, of point defects caused by an inferiority of the thin film
transistor, of line defects caused by severance of the gate and
data line, and of defective optical properties caused by a
difference of a cell thickness, for example, are inspected.
[0015] A conventional injection process for the liquid crystal cell
and the degree of the injection in the liquid crystal panel will be
explained hereinafter with reference to FIG. 2 and FIGS. 3A to 3C.
FIG. 2 is a schematic diagram illustrating a conventional injection
process of the liquid crystal and more particularly illustrating
the vacuum injection method whereby the liquid crystal material is
injected in a vacuum chamber using a pressure difference between
the interior and exterior of the liquid crystal cell. Though this
injection process is usually executed using a cell cassette that
loads a number of liquid crystal panels at one time, the injection
process will be described on the basis of one liquid crystal panel
for the sake of convenience. As shown in the FIG. 2, a vacuum
chamber 2 has an inlet 4, an outlet 6 for nitrogen gas, and a
container 10 having the liquid crystal 8 therein. The liquid
crystal panel 14 having the injection hole 12 is disposed over the
container 10 in the vacuum chamber 2. The seal pattern 13 is formed
along internal edges of the liquid crystal panel 14 except the
injection hole 12. The seal pattern is needed to form the cell gap
for the injection of the liquid crystal and to prevent the leakage
of the liquid crystal. Before the injection process is commenced,
the interior of the liquid crystal panel 14 should be vacuumed and
an autoclave process removing air bubbles in the liquid crystal
should be executed. If the liquid crystal with air bubbles is
injected into the liquid crystal panel, inferior goods may be
produced. If the pressure is changed rapidly to reduce the
injection time, the liquid crystal 8 may be altered and the liquid
crystal panel 14 may be deformed and damaged.
[0016] After air bubbles that exist in the liquid crystal panel 14
and in the liquid crystal 8 are adequately removed, the injection
hole 12 of the liquid crystal panel 14 is dipped into the container
10. At this time, if the interior of the liquid crystal panel 14 is
kept in a vacuum state of about 1/1000 Torr, the liquid crystal 8
in the container 10 is drawn into the interior of the liquid
crystal panel 14 through capillary action. When the liquid crystal
panel 14 is filled with the liquid crystal 8 to a certain degree,
nitrogen gas (N.sub.2) is supplied through the inlet 4 to cause a
pressure difference between the interior and exterior of the liquid
crystal panel 14. Accordingly, the liquid crystal fills the rest in
the gap of the liquid crystal panel.
[0017] FIGS. 3A to 3C are schematic diagrams illustrating a
movement of the liquid crystal injected in stages according to the
injection degree of the conventional liquid crystal panel 14. As
described in FIG. 2, the conventional injection process of the
liquid crystal is executed using capillary action and the pressure
difference. FIG. 3A shows an early stage of the liquid crystal
injection. When the injection hole 12 of the liquid crystal panel
14 contacts the liquid crystal 8, the liquid crystal 8 starts to
permeate into the liquid crystal panel 14 by capillary action. FIG.
3B shows an intermediate stage of the liquid crystal injection. As
shown in the figure, a front surface of the liquid crystal moving
upward forms a curved surface because of surface tension, and the
liquid crystal fills more than half of the liquid crystal panel 14.
FIG. 3C shows a last stage of the liquid crystal injection. At the
last stage of the liquid crystal injection, nitrogen gas is
supplied to the vacuum chamber to induce a pressure difference
between the interior and exterior of the liquid crystal panel as
described in FIG. 2, and accordingly, the liquid crystal comes to
fill the rest of the liquid crystal panel left vacant using the
pressure difference. However, when the liquid crystal 8 fills the
liquid crystal panel 14 to a certain degree, the shape of the front
surface of the liquid crystal moving upward is changed from the
curved surface to a flat surface due to an equilibrium between the
capillary climbing power of the liquid crystal and gravity, and
thus the speed of the liquid crystal injection slows down suddenly.
This phenomenon becomes more serious as the size of the liquid
crystal panel is larger. Due to the general trend in the industry,
the size of the liquid crystal panel has a tendency to increase.
Accordingly, those problems described above should be avoided to
increase a production yield of the liquid crystal display
device.
SUMMARY OF THE INVENTION
[0018] Accordingly, the present invention is directed to a liquid
crystal panel for a liquid crystal display device that
substantially obviates one or more of problems due to limitations
and disadvantages of the related art.
[0019] An object of the present invention is to provide a liquid
crystal panel, which has ribs therein in order to reduce an
injection time of the liquid crystal and thus increase a production
yield of the liquid crystal display device.
[0020] Additional features and advantages of the invention will be
set forth in the description which follows, and in part will be
apparent from the description, or may be learned by practice of the
invention. The objectives and other advantages of the invention
will be realized and attained by the structure particularly pointed
out in the written description and claims hereof as well as the
appended drawings.
[0021] To achieve these and other advantages and in accordance with
the purpose of the present invention, as embodied and broadly
described, a liquid crystal panel for a liquid crystal display
device comprises an upper substrate having color filters and black
matrices, a lower substrate having array elements, a seal pattern
between the upper and lower substrates, the seal pattern having an
injection hole, a liquid crystal between the upper and lower
substrates, and a plurality of ribs on an internal edge facing the
injection hole. The ribs are disposed on a region where black
matrices are formed and have a shape of the teeth of a comb. In
addition, an acryl-based resin is selected for a material used for
the ribs.
[0022] It is to be understood that both the foregoing general
description and the following detailed description are exemplary
and explanatory and are intended to provide further explanation of
the invention as claimed.
BRIEF DESCRIPTION OF THE DRAWINGS
[0023] The accompanying drawings, which are included to provide a
further understanding of the invention and are incorporated in and
constitute a part of this specification, illustrate embodiments of
the invention and together with the description serve to explain
the principles of the invention. In the drawings:
[0024] FIG. 1 is a flow chart illustrating a fabricating sequence
of liquid crystal cells for the conventional liquid crystal display
device;
[0025] FIG. 2 is a schematic diagram illustrating a conventional
injection process of liquid crystal;
[0026] FIGS. 3A to 3C are schematic diagrams illustrating movements
of the liquid crystal injected by stages according to the injection
degree of a conventional liquid crystal panel;
[0027] FIG. 4 is a simplified plan view illustrating a part of a
liquid crystal panel for a liquid crystal display device; and
[0028] FIGS. 5A to 5C are schematic diagrams illustrating movements
of the liquid crystal injected by stages according to the injection
degree of the liquid crystal panel of the present invention.
DETAILED DESCRIPTION OF THE EMBODIMENTS
[0029] Reference will now be made in detail to an embodiment of the
present invention, which is illustrated in the accompanying
drawings.
[0030] FIG. 4 is a simplified plan view illustrating a part of a
liquid crystal panel for a liquid crystal display device and only a
region whereto a liquid crystal is injected is shown in the figure
for convenience sake. As shown in the figure, a liquid crystal
panel 200 for a liquid crystal display device according to the
present invention comprises an upper substrate 100a having color
filters and black matrices (not shown) thereon, a lower substrate
100b having array elements (not shown) thereon, a seal pattern 110
disposed between the upper and lower substrates and having an
injection hole 104, a liquid crystal 106 injected between the upper
and lower substrate through the injection hole 104 of the seal
pattern 110, and a plurality of ribs 108 disposed on an internal
edge of the liquid crystal panel 100 facing the injection hole 104.
The ribs may be formed on a region of one of the substrates where
incident light is intercepted, and they may be formed on the region
where black matrices are formed. The ribs provide increased contact
area with the liquid crystal and maximize a capillary action,
thereby preventing a slow down of an injection speed of the liquid
crystal at the last stage of an injection. The ribs 108 may be
formed by a photolithographic process, and may be made of a
photosensitive material such as an acryl-based resin which is a
photo resin material.
[0031] FIG. 5A and 5B shows early and intermediate stages of the
liquid crystal injection according to the present invention. At
these stages the liquid crystal panel is filled with the liquid
crystal using the capillary action described with respect to FIG.
3A and 3B.
[0032] FIG. 5C shows a last stage of the liquid crystal injection.
When more than half of the liquid crystal panel 100 is filled with
the liquid crystal 106, the shape of the advancing surface of the
liquid crystal is changed from a curved surface to a flat surface.
When the liquid crystal 106 moving upward contacts the ribs 108
disposed in an upper part of the liquid crystal panel 100, the
liquid crystal 106 permeates into a space between each rib 108 by
maximizing the surface tension between the liquid crystal 106 and
the rib 108. Accordingly, the liquid crystal 106 fills the rest of
the interior of the liquid crystal panel 100 quickly using
capillary action. The liquid crystal injection method according to
the present invention may be used in various modes such as Twisted
Nematic (TN), In Plane Switching (IPS), Ferroelectric Liquid
Crystal (FLC) and Vertical Alignment (VA) mode, for example.
[0033] It will be apparent to those skilled in the art that various
modifications and variation can be made in the fabrication and
application of the present invention without departing from the
spirit or scope of the invention. Thus, it is intended that the
present invention cover the modifications and variations of this
invention provided they come within the scope of the appended
claims and their equivalents.
* * * * *