Liquid crystal cells – elements and systems – Particular excitation of liquid crystal – Electrical excitation of liquid crystal
Reexamination Certificate
1999-10-04
2002-05-21
Sikes, William L. (Department: 2871)
Liquid crystal cells, elements and systems
Particular excitation of liquid crystal
Electrical excitation of liquid crystal
C349S043000, C349S046000, C349S054000, C349S139000, C349S140000
Reexamination Certificate
active
06392721
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to a liquid crystal display device; and, more particularly, the invention relates to a liquid crystal display device in which the production yield is improved by eliminating the occurrence of a disconnection of a wired laminated portion in an active matrix liquid crystal display device of a thin film transistor (TFT) type or the like, as well as to a method of manufacturing the same.
Liquid crystal display devices have been widely utilized for displaying a variety of images, including still images and motion images. These liquid crystal display devices are basically classified into a first type (called the “simple matrix type”) wherein a liquid crystal layer is sandwiched between two substrates, at least one of which is made of transparent glass, and wherein a predetermined pixel is turned on/off by applying a voltage selectively to the various electrodes formed on the substrates for forming the pixels; and a second type (called the “active matrix type”) in which thin film transistors (TFTS) arc used as the switching elements, and wherein the various electrodes and pixel selecting switching elements are formed so that a predetermined pixel is turned on/off by selecting the switching elements.
In particular, the latter active matrix type liquid crystal display device has become very popular because of its contrast performance, its quick display performance and the like. In the active matrix type liquid crystal display device, the longitudinal field type device has been generally adopted, in which an electric field for changing the orientation of a liquid crystal layer is applied between electrodes formed on one substrate and electrodes formed on the other substrate. In recent years, however, a transverse field type (In-Plane Switching Mode: IPS type) liquid crystal display device has been developed, in which the direction of the electric field to be applied to the liquid crystal is generally in parallel with the substrate face.
FIG. 16
is an exploded perspective diagram illustrating the basic structure of one example of an active matrix type liquid crystal display device to which the present invention is applied.
FIG. 16
shows a specific structure of the liquid crystal display device (or a module which includes a liquid crystal display panel, a circuit substrate, a back light and other components in an integrated form: the module is called “MDL”) according to the present invention.
The liquid crystal display device has a shield case (also called the “metal frame”) SHD made of a metal sheet; a display window WD; insulating sheets INS
1
to INS
3
; circuit substrates, of which: PCB
1
denotes a drain side circuit substrate and a video signal line driving circuit substrate; PCB
2
denotes a gate side circuit substrate and a scanning signal line driving circuit substrate; and PCB
3
denotes an interface circuit substrate; joiners JN
1
to JN
3
for joining the circuit substrates PCB
1
to PCB
3
electrically; tape carrier packages TCP
1
and TCP
2
; a liquid crystal display panel PNL; a rubber cushion GC; a shielding spacer ISL; a prism sheet PRS; a scattering sheet SPS; a light guide board GLB; a reflection sheet RFS; a lower case (or mold frame) MCA, formed by integral molding and having an opening MO; a fluorescent lamp LP; a lamp cable LPC; a pressure sensitive adhesive double coated tape BAT, a rubber bushing GB for supporting the fluorescent lamp LP; and a back light BL composed of the fluorescent lamp and the light guide board. The scattering sheet members are stacked in the shown arrangement to assemble the liquid crystal display module MDL.
The liquid crystal display module MDL includes two kinds of accommodating/holding members of the lower case MCA and the shield case SHD and is constructed by integrating the metallic shield case SHD accommodating and fixing the insulating sheets INS
1
to INS
3
, the circuit substrates PCB
1
to PCB
3
and the liquid crystal display panel PNL, and the lower case MCA accommodating the back light BL composed of the fluorescent lamp LP, the light guide board GLB, the prism sheet PRS and the like.
On each of the drain side circuit substrate PCB
1
and the gate side circuit substrate PCB
2
, there is mounted an integrated circuit chip for driving the individual pixels of the liquid crystal display panel PNL. On the interface circuit substrate PCB
3
, there are mounted an integrated circuit chip for receiving video signals from an external host and control signals, such as timing signals, a timing converter (TCON) for generating clock signals by processing the timings, and the like. The clock signals generated by the timing converter are fed to the integrated circuit chip through a clock signal line which is laid on the interface circuit substrate PCB
3
as well as the drain side circuit substrate PCB
1
and the gate side circuit substrate PCB
2
. The interface circuit substrate PCB
3
, the drain side circuit substrate PCB
1
and the gate side circuit substrate PCB
2
are multi-layered wiring substrates, and the clock signal line is formed as an inner wiring line of the interface circuit substrate PCB
3
, the drain side circuit substrate PCB
1
and the gate side circuit substrate PCB
2
.
Here, the liquid crystal display panel PNL is constructed by joining the TFT substrate having TFTs and various wiring lines/electrodes and the filter substrate having the color filter and by seating the liquid crystal material in the clearance between the two substrates, such that the drain side circuit substrate PCB
1
for driving the TFTs, the gate side circuit substrate PCB
2
and the interface circuit substrate PCB
3
are connected by the tape carrier packages TCP
1
and TCP
2
, and such that the individual circuit substrates are connected by the joiners JN
1
, JN
2
and JN
3
.
FIG. 17
is a schematic diagram illustrating the wired structure in the vicinity of one pixel of the TFT substrate forming the liquid crystal display device shown in FIG.
16
. Reference numeral
1
designates a substrate; numeral
2
denotes a scanning signal line (a gate line, a gate wiring line or a gate electrode); numeral
2
denotes an adjacent scanning signal line (an adjoining gate line), numeral
3
denotes a video signal line (a drain line or a drain electrode); numeral
4
denotes a source electrode (a source line or a source electrode); numeral
5
denotes a pixel electrode; letters TFT designate a thin film transistor; and letters Cadd designate a capacity added element.
In
FIG. 17
, the central portion of the substrate
1
, except for the periphery, provides a display area which is filled up with a liquid crystal in the clearance which is formed by joining the other substrate (filter substrate) to it. In this display area, moreover, there are formed the scanning signal line
2
(or gate line) extending in the X-direction, as viewed in
FIG. 17
, and the video signal line
3
(or drain line) extending in the Y-direction. There is further formed the source electrode
4
which extends in the Y-direction, while being insulated from the scanning signal line
2
and which also extends in the X-direction. The region defined by the scanning signal line
2
and the video signal line
3
constitutes one region for each pixel. In other words, the aforementioned display area is formed of a set of numerous pixel regions arranged in a matrix shape.
Each pixel region is composed of a thin film transistor TFT to be turned on when the scanning signal is fed from the scanning signal line
2
and the video signal line
3
, and a pixel electrode
5
which receives a video signal from the video signal line
3
through the thin film transistor TFT, which is turned on. In addition to the thin film transistor TFT and pixel electrode
5
, a capacity added clement Cadd is formed between the scanning signal line
2
′ adjoining the scanning signal line
2
for driving the thin film transistor TFT and the aforementioned pixel electrode
5
. This capacity added clement Cadd is provided for storing the video signal in the pixel el
Fujii Kazumi
Kaneko Toshiki
Ochiai Takahiro
Takahashi Takuya
Antonelli Terry Stout & Kraus LLP
Hitachi , Ltd.
Ngo Julie
Sikes William L.
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