Liquid crystal cells – elements and systems – Particular structure – Having significant detail of cell structure only
Reexamination Certificate
2000-10-17
2003-09-09
Ton, Toan (Department: 2871)
Liquid crystal cells, elements and systems
Particular structure
Having significant detail of cell structure only
C345S098000
Reexamination Certificate
active
06618111
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to a liquid crystal display device, in particular, to a packaging structure in which a liquid crystal display panel and a circuit substrate which supplies a drive voltage and a drive signal as liquid-crystal-drive signals are mounted to a liquid crystal display device.
BACKGROUND OF THE INVENTION
Conventionally, a TCP (tape carrier package) or COG (chip on glass) packaging technique is used to mount, to a liquid crystal display device, a liquid crystal panel and a circuit substrate, drive IC, etc. which supply a drive signal and a drive voltage as liquid-crystal-drive signals to the liquid crystal panel.
According to TCP packaging, as shown in
FIG. 11
, a liquid crystal panel
101
is connected to flexible substrates (hereinafter, will be referred to TCPs)
102
carrying a liquid crystal drive IC thereon, and receives a drive voltage and a drive signal from the liquid crystal drive IC mounted to the TCPs
102
.
Each TCP
102
receives an external drive voltage and drive signal via the circuit substrate
103
connected to the TCP
102
opposite to the panel.
The circuit substrate
103
for use with a TCP technique requires numerous input signal lines to transmit the drive voltage and the drive signal to the TCPs
102
. Therefore, the circuit substrate
103
is normally fabricated from a multilayer plate including four to eight conductor layers and measures 5 mm to 10 mm in width and 0.6 mm to 1 mm in thickness.
As described above, according to a TCP technique, numerous lines are needed to transmit the drive voltage and the drive signal to the TCPs
102
via the circuit substrate
103
for use with the liquid crystal display device; therefore, the circuit substrate
103
is either bulky, or compact but costly due to multilayer wiring or other special techniques involved.
Japanese Laid-Open Patent Application No. 8-146449/1996 (Tokukaihei 8-146449; published on Jun. 7, 1996) discloses another packaging structure, which is an application of a TCP technique. This packaging structure is similar to conventional TCP techniques in that there are provided TCPs in the peripheral part of a liquid crystal panel and also that flexible wiring substrates are lined along the outer edge of a row of TCPs. The distinction lies where the wires on the flexible wiring substrates and the wires on the TCPs are connected to each other in the gaps between the TCPs in this structure, while they are connected in the gaps between the flexible wiring substrates and the TCPs according to conventional techniques. This structure thus enables reduction in dimensions of the peripheral part (frame) of the liquid crystal panel.
The arrangement is equivalent to a packaging structure used in a conventional TCP technique, with an only change in the location of the area where the wires on the flexible wiring substrates and the wires on the TCPs are connected to each other. The disclosed structure therefore cannot reduce the number of wires formed on the flexible wiring substrates. Besides, the wires on the flexible wiring substrates need additional length, in comparison to conventional wires, so as to reach the gaps between the TCPs. If the flexible wiring substrates need to be further elongated to suit increased dimensions of the panel, the drive signal and the drive voltage are likely to deteriorate during transmission. The issue will be elaborated again later.
Meanwhile, according to a COG technique, as shown in
FIG. 12
, liquid crystal drive ICs
112
and circuit substrates
113
for supplying a drive voltage and a drive signal to the liquid crystal drive ICs
112
are disposed in the peripheral part of a glass substrate
111
a
constituting a liquid crystal panel
111
.
As described above, according to a COG technique, the circuit substrate
113
supplies a drive voltage and a drive signal to the liquid crystal drive ICs
112
; therefore, the circuit substrate
113
can be readily connected to the liquid crystal panel
111
.
As mentioned earlier, packaging of panels, which are becoming increasingly larger, using a TCP technique cause the drive signal and the drive voltage to decay during transmission. The decay occurs because the drive signal and the drive voltage are provided externally and must be passed through an area (supply point) which is located, for example, near a corner of the liquid crystal panel on the flexible wiring substrate, before being applied to the TCPs via the wires on the wiring substrates. The longer distance the drive signal and the drive voltage need to propagate from the supply point to the TCPs, the further they decay. Such deterioration does not occur in a liquid crystal display device with an about 10-inch display under typical conditions. The drive signal, however, cannot be transmitted in a 15-inch or larger liquid crystal display device, because the distance grows between the TCPs located at both ends, and the resultant large resistance of the wires on the flexible wiring substrate causes a large voltage drop.
If the drive signal can be successfully transmitted to all the TCPs in a 15-inch or even larger liquid crystal display device, there is a further problem: the drive voltage is more likely to decay and more difficult to transmit properly than the drive signal. To address this problem, a separate circuit substrate becomes necessary to supply a drive voltage to TCPs. This inevitably requires more investment in manufacturing machines and results in higher manufacturing cost in the manufacture of liquid crystal display devices.
Meanwhile, according to the aforementioned COG technique, as shown in
FIG. 12
, the circuit substrate
113
supplies the drive voltage and the drive signal to the liquid crystal drive ICs
112
. The circuit substrate
113
can be readily connected to the liquid crystal panel
111
in an about 10-inch liquid crystal display device. It can, however, be connected to them only with difficulties in a 15-inch or larger liquid crystal display device due to the increased dimensions of the circuit substrate
113
.
Besides, in the COG technique, the liquid crystal drive IC
112
and the circuit substrates
113
are connected to the peripheral part of the liquid crystal panel
111
. This structure increases the total dimensions of the liquid crystal display device only without ever contributing to an increase in the screen size.
SUMMARY OF THE INVENTION
To address these problems, the present invention has an object to offer a liquid crystal display device of such a packaging structure that a drive voltage can be supplied to TCPs without being affected adversely by a voltage drop caused by an increased resistance of wires despite a growth in size of a liquid crystal panel.
To achieve the object, a liquid crystal display device in accordance with the present invention includes a liquid crystal panel in which a liquid crystal is interposed between two substrates on which drive electrodes for driving the liquid crystal are provided,
the liquid crystal panel including:
electrode-connecting-terminal sections (TCPs) each connected to a predetermined number of the drive electrodes and provided with drive means which is capable of driving the predetermined number of the drive electrodes; and
a circuit substrate for supplying a liquid-crystal-drive signal to the electrode-connecting-terminal sections,
wherein:
connecting wires are provided between a pair of adjacent electrode-connecting-terminal sections so as to transmit the signal supplied by the circuit substrate sequentially from one electrode-connecting-terminal section to a next; and
stabilizer means is provided between at least a pair of adjacent electrode-connecting-terminal sections so as to stabilize the signal transmitted via the connecting wires.
According to the arrangement, stabilizer means is provided to stabilize the signal transmitted via the connecting wires connecting adjacent electrode-connecting-terminal sections. Therefore, the liquid crystal display device is not affected adversely by a voltage drop caused by an increased resistance of wires despit
Kawaguchi Hisao
Nagata Katsunori
Sakaki Yoichiro
Akkapeddi P. R.
Nixon & Vanderhye P.C.
Sharp Kabushiki Kaisha
Ton Toan
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