U.S. patent application number 09/782214 was filed with the patent office on 2002-03-07 for process for repairing defect applied in liquid crystal display.
Invention is credited to Chang, Shou-Jen, Cheng, Jia-Shyong, Li, Hsien-Hua.
Application Number | 20020027128 09/782214 |
Document ID | / |
Family ID | 21661059 |
Filed Date | 2002-03-07 |
United States Patent
Application |
20020027128 |
Kind Code |
A1 |
Cheng, Jia-Shyong ; et
al. |
March 7, 2002 |
Process for repairing defect applied in liquid crystal display
Abstract
A process is provided for repairing a defect applied in
producing a liquid crystal display, wherein the liquid crystal
display includes a repair circuit structure, and at least one color
filter and a liquid crystal formed on a front thereof. The process
includes steps of (a) providing a laser having a wavelength of
infrared spectrum, and (b) welding the repair circuit from a back
of the liquid crystal display by the laser to repair the
defect.
Inventors: |
Cheng, Jia-Shyong; (Hsinchu
Shien, TW) ; Chang, Shou-Jen; (Hsinchu, TW) ;
Li, Hsien-Hua; (Taipei Shien, TW) |
Correspondence
Address: |
Edwards & Angell, LLP
130 Water Street
Boston
MA
02109-4280
US
|
Family ID: |
21661059 |
Appl. No.: |
09/782214 |
Filed: |
February 13, 2001 |
Current U.S.
Class: |
219/121.64 |
Current CPC
Class: |
G02F 1/136263 20210101;
G02F 1/136259 20130101 |
Class at
Publication: |
219/121.64 |
International
Class: |
B23K 026/22 |
Foreign Application Data
Date |
Code |
Application Number |
Sep 6, 2000 |
TW |
089118264 |
Claims
What is claimed is:
1. A process for repairing a defect applied in producing a liquid
crystal display, wherein said liquid crystal display comprises a
repair circuit structure, and at least one color filter and a
liquid crystal formed on a front thereof, comprising steps of: (a)
providing a laser having a wavelength of infrared spectrum; and (b)
welding said repair circuit from a back of said liquid crystal
display by said laser to repair said defect.
2. The process according to claim 1, wherein said repair circuit is
a point defect repair circuit.
3. The process according to claim 1, wherein said repair circuit is
a line defect repair circuit.
4. A process for repairing a defect applied in producing a liquid
crystal display, wherein said liquid crystal display comprises a
repair circuit structure, and at least one color filter and a
liquid crystal formed on a front thereof, comprising steps of: (a)
providing a laser; and (b) welding said repair circuit from a back
of said liquid crystal display by said laser to repair said
defect.
5. The process according to claim 4, wherein said laser has a
wavelength of infrared spectrum.
6. The process according to claim 4, wherein said repair circuit is
a point defect repair circuit.
7. The process according to claim 4, wherein said repair circuit is
a line defect repair circuit.
8. A process for repairing a defect applied in producing a liquid
crystal display, wherein said liquid crystal display comprises a
repair circuit structure, and at least one color filter and a
liquid crystal formed on a front thereof, comprising steps of: (a)
providing a laser having a wavelength of infrared spectrum; and (b)
welding said repair circuit by said laser to repair said
defect.
9. The process according to claim 8, wherein said laser performed
in said welding step is from a back of said liquid crystal
display.
10. The process according to claim 8, wherein said repair circuit
is a point defect repair circuit.
11. The process according to claim 8, wherein said repair circuit
is a line defect repair circuit.
Description
FIELD OF THE INVENTION
[0001] The present invention relates to a process for repairing
defects, and more particularly to a process for repairing defects
of a thin film transistor liquid crystal display (TFTLCD).
BACKGROUND OF THE INVENTION
[0002] Along with the producing technology development, the liquid
crystal display has been become a widely used display device. The
working principle of the liquid crystal display is based on the
phenomenon that the alignment condition of liquid crystal molecules
is changed by applying an electrical field to change the path of
light passing through the liquid crystal molecules and the display
effect of changing in light and shade is further achieved.
[0003] FIG. 1 is a diagram illustrating a unit circuit block of a
thin film transistor liquid crystal display according to the prior
art. The thin film transistor 11 is controlled by the voltage Vs of
scanning line for switching the statuses of "on" and "off". The
voltage Vd of the data line is applied to a liquid crystal 12
located between a pixel electrode 131 and a common electrode 132
for changing the alignment condition of the liquid crystal 12 and
further controlling the light penetrating degree of the liquid
crystal molecules 12. Thus, the emissive intensity from a light
source 14 at the back of the liquid crystal display will occur
change while the light reaches to the eyes of a user for achieving
the display effect of the changing in light and shade. The storage
capacitance 15 is used for reinforcing the device
characteristics.
[0004] The thin film transistor liquid crystal display is formed by
producing a lot of arrays constructed by the unit circuit as shown
in FIG. 1 on a display panel. However, some defects in the thin
film transistor or the connecting line are possible to occur by
mistake or through carelessness. The defects will cause a portion
of pixel points in the liquid crystal display cannot be operated
normally and further seriously affect the image quality of the
liquid crystal display. For ruling out the problems caused by the
point or line defects, a repair circuit structure is established in
the layout of the current thin film transistor liquid crystal
display.
[0005] FIG. 2A is a top view illustrating a structure of a point
defect repair circuit according to the prior art. A repair region
21 is located on a portion of a scanning line 221 overlapped with a
portion of a pixel electrode 222 as shown in FIG. 2A. When a thin
film transistor 20 is damaged, which results in the pixel point
occur the glow point, the laser is applied to the repair region 21
for welding the scanning line 221 and the pixel electrode 222
together to form a common electric potential condition. Thus, the
pixel point will not occur apparent glow point for achieving the
repairing action.
[0006] FIGS. 2B-2C are a top view and a sectional view of a
structure of a line defect repair circuit according to the prior
art. FIG. 2B illustrates a line defect repair circuit locates
between a thin film transistor array 20 and an external control
circuit 27. As shown in FIG. 2C, a first metal layer 23 and a
second metal layer 24 are electrically connected to a conducting
structure 25, respectively. An insulating layer 26 is located
between the first metal layer 23 and a second metal layer 24 for
insulation. When a defect occurs in a region 251 of the conducting
structure 25, a laser is applied to weld a region of the insulating
layer 26 which is in contact with the first metal layer 23 and the
second metal layer 24 at the same time. Upon the region of the
insulating layer 26 is broken by the laser, the first metal layer
23 and the second metal layer 24 are fused to form a region 28 for
efficiently achieving the repairing action.
[0007] For typical technology, the point or line defect can be
detected when the thin film transistor array is finished. The
defect can be welded from the front side by a laser having a
wavelength of green spectrum for repairing. However, some defects
cannot be detected in this stage or occurred in the following
stages. At this moment, the upper glass substrate, the color filter
and the liquid crystal have already formed on the thin film
transistor array, so the color filter and the liquid crystal will
be damaged if using a laser having a wavelength of green spectrum
is employed for repairing the defect according to the prior art.
Hence, generally, the product having the defect is not repaired and
would be discarded as the inferior products. Thus, the yield will
be decreased because of the defect problem.
[0008] Therefore, the purpose of the present invention is to
develop a process to deal with the above situations encountered in
the prior art.
SUMMARY OF THE INVENTION
[0009] It is therefore an object of the present invention to
propose a process for repairing a defect applied in producing a
liquid crystal display to avoid damaging both a color filter and a
liquid crystal formed on the liquid crystal display.
[0010] It is therefore another object of the present invention to
propose a process for repairing a defect applied in producing a
liquid crystal display to reduce the inferior product occurred.
[0011] It is therefore an additional object of the present
invention to propose a process for repairing a defect applied in
producing a liquid crystal display to improve the yield.
[0012] According to the present invention, there is proposed a
process for repairing a defect applied in producing a liquid
crystal display, wherein the liquid crystal display includes a
repair circuit structure, and at least one color filter and a
liquid crystal formed on a front thereof. The process includes
steps of (a) providing a laser having a wavelength of infrared
spectrum, and (b) welding the repair circuit from a back of the
liquid crystal display by the laser to repair the defect.
[0013] Certainly, the repair circuit can be a point defect repair
circuit or a line defect repair circuit.
[0014] According to the present invention, there is proposed a
process for repairing a defect applied in producing a liquid
crystal display, wherein the liquid crystal display includes a
repair circuit structure, and at least one color filter and a
liquid crystal formed on a front thereof. The process includes
steps of (a) providing a laser, and (b) welding the repair circuit
from a back of the liquid crystal display by the laser to repair
the defect.
[0015] Preferably, the laser has a wavelength of infrared
spectrum.
[0016] Certainly, the repair circuit can be a point defect repair
circuit or a line defect repair circuit.
[0017] According to the present invention, there is proposed a
process for repairing a defect applied in producing a liquid
crystal display, wherein the liquid crystal display includes a
repair circuit structure, and at least one color filter and a
liquid crystal formed on a front thereof. The process includes
steps of (a) providing a laser having a wavelength of infrared
spectrum, and (b) welding the repair circuit by the laser to repair
the defect.
[0018] Preferably, the laser performed in the welding step is from
a back of the liquid crystal display.
[0019] Certainly, the repair circuit can be a point defect repair
circuit or a line defect repair circuit.
[0020] The present invention may best be understood through the
following description with reference to the accompanying drawings,
in which:
BRIEF DESCRIPTION OF THE DRAWINGS
[0021] FIG. 1 is a diagram illustrating a unit circuit block of a
thin film transistor liquid crystal display (TFTLCD) according to
the prior art;
[0022] FIG. 2A is a top view illustrating a structure of a point
defect repair circuit according to the prior art;
[0023] FIG. 2B is a top view illustrating a structure of a line
defect repair circuit according to the prior art;
[0024] FIG. 2C is a sectional view illustrating a structure of a
line defect repair circuit according to the prior art; and
[0025] FIG. 3 is a sectional view illustrating a structure of a
thin film transistor liquid crystal display having a color filter
and a liquid crystal formed thereon according to the present
invention.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0026] As shown in FIG. 3A, a color filter 31 and a liquid crystal
32 are formed on a thin film transistor liquid crystal display. The
structure of a point or line defect repair circuit is constructed
by a first metal layer 33, an insulating layer 35 and a second
metal layer 34, which are in order formed on the front of a glass
substrate 30 as shown in FIG. 3. When a point or line defect
occurred and found after finishing the color filter 31 and the
liquid crystal 32 on the thin film transistor liquid crystal
display, a laser having a wavelength of infrared spectrum can be
provided to illuminate from the back of the glass substrate 30 for
repairing the point or line defect. The first metal layer 33 and
the second metal layer 34 are welded by the laser, so the
insulating layer 35 is broken to fuse the first metal layer 33 with
the second metal layer 34 for achieving the electricity. Thus, the
defect in the thin film transistor liquid crystal display can be
efficiently repaired.
[0027] In sum, even though the color filter 31 and the liquid
crystal 32 are finished, the method according to the present
invention can repair the point or line defect by using the laser
having a predetermined wavelength and illuminating directions.
Furthermore, according to the present invention, the thin film
transistor liquid crystal display can be repaired without damaging
the color filter or the liquid crystal. Therefore, the present
invention can avoid producing the defect products for efficiently
increasing the yield.
[0028] While the invention has been described in terms of what are
presently considered to be the most practical and preferred
embodiments, it is to be understood that the invention need not to
be limited to the disclosed embodiment. On the contrary, it is
intended to cover various modifications and similar arrangements
included within the spirit and scope of the appended claims which
are to be accorded with the broadest interpretation so as to
encompass all such modifications and similar structures.
* * * * *