Electric heating – Metal heating – By arc
Reexamination Certificate
2001-02-13
2002-10-01
Heinrich, Samuel M. (Department: 1725)
Electric heating
Metal heating
By arc
Reexamination Certificate
active
06459070
ABSTRACT:
FIELD OF THE INVENTION
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
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.
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.
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.
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.
2
A. 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.
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.
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.
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
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.
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.
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.
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.
Certainly, the repair circuit can be a point defect repair circuit or a line defect repair circuit.
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.
Preferably, the laser has a wavelength of infrared spectrum.
Certainly, the repair circuit can be a point defect repair circuit or a line defect repair circuit.
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.
Preferably, the laser performed in the welding step is from a back of the liquid crystal display.
Certainly, the repair circuit can be a point defect repair circuit or a line defect repair circuit.
The present invention may best be understood through the following description with reference to the accompanying drawings, in which:
REFERENCES:
patent: 5171963 (1992-12-01), Saruta et al.
patent: 6340806 (2002-01-01), Smart et al.
patent: 2244374 (1991-11-01), None
Chang Shou-Jen
Cheng Jia-Shyong
Li Hsien-hua
Corless Peter F.
Edwards & Angell LLP
Hannastar Display Corp.
Heinrich Samuel M.
O'Day Christine C.
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