Active solid-state devices (e.g. – transistors – solid-state diode – Physical configuration of semiconductor – With peripheral feature due to separation of smaller...
Reexamination Certificate
1999-07-06
2001-01-09
Ng{circumflex over (o)}, Ng{circumflex over (a)}n V. (Department: 2814)
Active solid-state devices (e.g., transistors, solid-state diode
Physical configuration of semiconductor
With peripheral feature due to separation of smaller...
C257S059000, C257S072000, C257S350000
Reexamination Certificate
active
06172410
ABSTRACT:
FIELD OF THE INVENTION
This invention relates to a collective substrate of active-matrix substrates that is used for an active-matrix liquid crystal display panel, in which a driving signal is applied via a switching element to a pixel electrode and a potential difference between electrodes opposing each other enables to provide a display.
BACKGROUND OF THE INVENTION
Conventionally, a liquid crystal display device has been provided with a plurality of pixel electrodes which are disposed in a matrix form, and opposing electrodes which oppose the pixel electrodes and serve as common electrodes. Liquid crystal serving as a display medium exists between the pixel and opposing electrodes. When a display is provided, a potential is selectively written by the pixel electrodes, and a voltage difference between the pixel electrodes and the opposing electrodes allows the liquid crystal existing therebetween to be subjected to an optical modulation, so that a display pattern is visually observed.
An active-matrix driving method has been known as a method for driving the pixel electrodes disposed in a matrix form. Each of the pixel electrodes is connected with a switching element and is driven by the switching element. A TFT (thin-film transistor) and an MIM (metal-insulating film-metal) elements are generally used as the switching element.
An active-matrix liquid crystal display device includes an active-matrix liquid crystal display panel, in which: (a) an active-matrix substrate having a plurality of scanning lines and a plurality of signal lines disposed so as to intersect one another on a transparent insulating substrate, each of the intersections having a pixel electrode and a switching element for driving the pixel electrode, and (b) an opposing substrate having opposing electrodes formed on a transparent insulating substrate, are provided with alignment films on the respective opposing surfaces and are bonded to each other via a liquid crystal layer.
FIG. 15
shows a construction of one pixel of the active-matrix substrate, which uses the TFT element (hereinafter, abbreviated as TFT) as the switching element.
A scanning line
2
is connected with a gate electrode of a pixel TFT
101
, and a scanning signal inputted therein drives the pixel TFT
101
. A signal line
3
is connected with a source electrode of the pixel TFT
101
and a display signal (video signal) is inputted therein. A drain electrode of the pixel TFT
101
is connected with a pixel electrode
104
and one of the terminals of an auxiliary capacity via an auxiliary capacity electrode
108
. The other terminal of the auxiliary capacity is connected with an auxiliary capacity wire
4
. Upon constructing a liquid crystal cell, the other terminal is connected to the opposing electrode disposed on the opposing substrate. On the insulating substrate, the pixel TFTs
101
and the pixel electrodes
104
are disposed in a matrix form.
FIG. 16
shows an example of the cross section of the active-matrix substrate. On an insulating substrate
117
, a gate electrode
118
, a gate insulating film
119
, a semiconductor layer
120
, an n
+
-Si layer
121
serving as source and drain electrodes, a metal layer serving as a signal line
3
, a between-layer insulating film
123
, and a transparent conductor layer serving as a pixel electrode
104
are successively formed. The pixel electrode
104
is connected with the drain electrode of the pixel TFT
101
via a contact hole
125
penetrating the between-layer insulating film
123
, specifically, via the auxiliary capacity electrode
108
.
In the construction of
FIG. 16
, the between-layer insulating film
123
is formed between the scanning line
2
(disposed on the same layer as the gate electrode
118
) and signal line
3
and the pixel electrode
104
; thus, it is possible to allow the pixel electrode
104
to overlap the signal line
3
. Such a construction makes it possible to improve an aperture rate and to shield an electric field caused by the signal line
3
; consequently, alignment defects are prevented in liquid crystal.
Next, referring to
FIG. 17
, a succeeding process is described.
FIG. 17
is a plan model view of the conventional active-matrix liquid crystal display device. Here,
FIG. 17
illustrates a state in which one cell is cut out so as to correspond to each of the display devices of a large substrate. Actually, in many cases, a collective substrate is manufactured so as to include several cells formed laterally and longitudinally.
A polyimide alignment film is formed on an effective display area (inside a phantom line)
167
of a completed active-matrix substrate
150
, and an aligning function is added by using an operation such as a rubbing operation. on an opposing substrate
151
as well, transparent opposing electrodes (not shown) including ITO (indium tin oxide) are formed, and then, a part corresponding to the effective display area
167
is subjected to the same operation.
Around the liquid crystal display panel, except for an inlet for filling liquid crystal (not shown), a sealing material (not shown) is applied thereon by using a printing method so as to surround the panel. Further, a conductive material
159
is applied to an opposing substrate signal input terminal
157
disposed on the active-matrix substrate
150
, and then, spacers (not shown) are dispersed for maintaining a cell thickness of the liquid crystal layer, the active-matrix substrate
150
is bonded to the opposing substrate, and a heating operation is performed so as to harden the sealing material.
Afterwards, the cells, which are formed laterally and longitudinally in the collective substrate of the active-matrix substrate
150
, are cut out one by one, liquid crystal is filled from the liquid crystal inlet, and the liquid crystal inlet is filled with the sealing material so as to achieve the panel of the liquid crystal display device. And then, a source driver
160
a
for applying a display signal to each of the signal lines
3
, a gate driver
160
b
for applying a scanning signal to each of the scanning lines
2
, a control circuit (not shown), a back light (not shown), and other members are installed so as to complete the liquid crystal display device. Here, the liquid crystal display device of
FIG. 17
is not provided with the auxiliary capacity wire
4
.
Normally, on such a liquid crystal display device, an optical inspection is performed in each step of the process, an electrical inspection is performed when the active-matrix substrate is completed, and a lighting and an electrical inspections are performed between when the panel is completed and when members including a driver have been installed.
These inspections are carried out so as not to allow defected portions to remain in the succeeding process. The defected portions cause loss of materials and works. When a defect is found, the substrate is discarded immediately, or the defect is corrected by using a means such as a laser.
Incidentally, because of the recent improvement of manufacturing techniques, a liquid crystal display panel has offered a higher definition. Accordingly, the inspection also requires a more improved technique.
Namely, terminals for inputting signals to the signal lines
3
and the scanning lines
2
has a shorter pitch. When pins electrically become contact with the lines so as to supply signals, it is necessary to provide an extremely fine and expensive probe. Further, in some cases, even small dust on the terminal does not allow a normal lighting upon inspection; thus, an inspection defect may be mistakenly recognized as a defect of the panel. In order to solve this problem, the inspection needs to be performed in an extremely clean environment. Therefore, it is necessary to increase the total cost.
Hence, in order to realize a simpler lighting inspection performed upon completion of the panel, in the liquid crystal display device of
FIG. 17
, the signal lines
3
and scanning lines
2
for applying the same signals upon inspection are respectively short-circuited by inspection displa
Katayama Mikio
Nagata Hisashi
Takahama Manabu
Yamashita Toshihiro
Ng{circumflex over (o)} Ng{circumflex over (a)}n V.
Nixon & Vanderhye PC
Sharp Kabushiki Kaisha
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