Liquid crystal cells – elements and systems – Particular structure – Having significant detail of cell structure only
Reexamination Certificate
2002-11-05
2004-05-11
Chowdhury, Tarifur R. (Department: 2871)
Liquid crystal cells, elements and systems
Particular structure
Having significant detail of cell structure only
C349S152000
Reexamination Certificate
active
06734941
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a liquid crystal display device, and more particularly to a liquid crystal display device which can enhance the reliability by obviating the occurrence of cracks in a substrate of a liquid crystal display panel when output terminals of a flexible printed circuit board are connected to electrode terminals of a liquid crystal display panel by compression bonding.
2. Description of the Related Art
In a panel type display device such as a liquid crystal display device, a display region having a plurality of pixels constituted of electrodes and active elements is formed on an inner surface of an insulating substrate made of glass or the like, and a flexible printed circuit board is popularly used as connection means between driving circuits of the pixels and external devices such as host computers for applying signals and voltages for displaying (hereinafter also referred to as display signals) to these pixels. Here, the explanation is made using the liquid crystal display device as an example, the same goes for an organic EL display device, a field emission type cathode ray tube and the like.
For example, in an active matrix type liquid crystal display device which is currently well known as this type of panel type display device, in general, a display region having active elements such as thin film transistors provided for respective pixels is formed on one substrate of a liquid crystal display panel which sandwiches liquid crystal between two sheets of substrates, and a plurality of driving circuit chips which perform switching driving of these active elements are provided on a periphery of the substrate or in the vicinity of the periphery of the substrate.
Various methods have been known as modes for mounting the driving circuit chips on the liquid crystal display panel. One of such modes is a so-called flip chip method (hereinafter referred to as “FCA method”) which directly mounts the driving circuit chips on the periphery of the substrate which constitutes the liquid crystal display panel. Besides such a method, a method which mounts the above-mentioned driving circuit chips on the flexible printed circuit board or a method which mounts the above-mentioned driving circuit chips on an interface substrate interposed between the liquid crystal display panel and the external device has been commercialized. In these methods, electrode terminals are pulled out from the display region of the liquid crystal display panel and outputs of the driving circuit chips which apply display signals to these electrode terminals are connected to the electrode terminals.
In the FCA method, the output terminals of the driving circuit chips are directly connected to the above-mentioned electrode terminals. Further, to panel input terminals which are formed on the glass substrate and are connected with input terminals of the driving circuit chips, the output terminals of the flexible printed circuit board are connected through an anisotropic conductive film by compression bonding.
In the method which mounts the driving circuit chips on the flexible printed circuit board or in the method which mounts the driving circuit chips on the interface substrate, the electrode terminals which are pulled out from the display region of the liquid crystal display panel are used as the panel input terminals and the output terminals of the flexible printed circuit board are connected to these panel input terminals using the same means by compression bonding.
Further, various methods have been also proposed for supplying display signals and, recently, a data transfer method which sequentially transfers display signals with respect to a plurality of driving circuit chips mounted in the FCA method has been popularly adopted. This data transfer method is a method which sequentially transfers driving signals to the driving circuit chip of succeeding stage in response to the completion of the pixel selection operation of the driving circuit chip of preceding stage. This data transfer method reduces a burden incurred by wiring at the flexible printed circuit board side by mounting some display signal paths on the substrate of the liquid crystal display panel.
FIG.
7
A and
FIG. 7B
are schematic views for explaining an essential part of a liquid crystal display device in which a flexible printed circuit board is connected to a liquid crystal display panel adopting the data transfer method which is provided with driving circuit chips of FCA method.
FIG. 7A
is a plan view of the liquid crystal display device and
FIG. 7B
is a cross-sectional view taken along a line A-A′ in FIG.
7
A. In FIG.
7
A and
FIG. 7B
, reference symbol SUB
1
indicates one substrate which constitutes a liquid crystal display panel LCD, reference symbol SUB
2
indicates another substrate which constitutes the liquid crystal display panel LCD, reference symbol CH
1
indicates driving circuit chips at a scanning signal supply side (hereinafter also referred to as gate drivers), and reference symbol CH
2
indicates driving circuit chips at a video signal supply side (hereinafter also referred to as drain drivers).
Further, reference symbol FPC
1
indicates a first flexible printed circuit board which is connected to one substrate SUB
1
side on which the gate drivers CH
1
are mounted and reference symbol FPC
2
indicates a second flexible printed circuit board which is connected to one substrate SUB
1
side on which the drain drivers CH
2
are mounted. The constitution around the wiring of the first flexible printed circuit board FPC
1
and the gate drivers CH
1
of the liquid crystal display panel LCD is substantially equal to the constitution around the wiring of the second flexible printed circuit board FPC
2
and the drain drivers CH
2
, so that the constitution around the wiring of the first flexible printed circuit board FPC
1
and the gate driver CH
1
of the liquid crystal display panel LCD is explained here.
With respect to the first flexible printed circuit board FPC
1
, on a base film BFM, a wiring pattern PTN having an input terminal portion TM which is connected to an interface printed circuit board not shown in the drawing and output terminals FTM which are connected to the wiring pattern PTN are formed. Here, the output terminals FTM are exposed from a cover film. Although the wiring pattern PTN is covered with the cover film in the same manner except for the output terminals FTM and the input terminal portion TM (a connection portion with the interface substrate) provided to an end portion of the wiring pattern PTN, the illustration of such a constitution is omitted from FIG.
7
A and FIG.
7
B.
The wiring pattern PTN of the first flexible printed circuit board FPC
1
is formed to be extended in the longitudinal direction of the first flexible printed circuit board FPC
1
from an input terminal portion TM thereof connected to an interface printed circuit board (not shown in the drawing). Output terminals FTM of the first flexible printed circuit board FPC
1
are arranged as a plurality of groups of terminals protruded between a plurality of gate drivers CH
1
respectively from the region where the wiring pattern PTN is formed in the direction transverse to the wiring pattern PTN.
The output terminals FTM of the first flexible printed circuit board FPC
1
are exposed to overlap to panel inputting terminals LTM of the liquid crystal display panel LCD in an opposed manner and are connected to the panel inputting terminals LTM using an anisotropic conductive film ACF. Here, the panel inputting terminals LTM which constitute inputting terminals of the driving printed circuit board are not shown in FIG.
7
A. Each of terminal groups being formed of plural terminals is simply described as a terminal for convenience in this specification.
SUMMARY OF INVENTION
This compression bonding connection is performed by heating and pressing to a substrate (a first substrate SUB
1
) of a liquid crystal display panel LCD in a direction indicated by an arrow
Kawamura Tetsuya
Oosone Tomio
Yamazaki Hiroyuki
Chowdhury Tarifur R.
Chung David Y.
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