Liquid crystal cells – elements and systems – Particular structure – Having significant detail of cell structure only
Reexamination Certificate
2001-02-16
2004-12-21
Chowdhury, Tarifur R. (Department: 2871)
Liquid crystal cells, elements and systems
Particular structure
Having significant detail of cell structure only
C349S108000, C349S144000, C349S149000
Reexamination Certificate
active
06833888
ABSTRACT:
This application claims the benefit of Korean Patent Application No. 2000-7715, filed on Feb. 18, 2000, which is hereby incorporated by reference for all purposes as if fully set forth herein.
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a liquid crystal display (LCD) device, and more particularly, to a LCD device having color filters arranged in a stripe shape.
2. Discussion of the Related Art
In general, the LCD device includes a liquid crystal panel having upper and lower substrates and an interposed liquid crystal layer. The upper substrate, referred to as a color filter substrate, includes a common electrode and color filters. The lower substrate is called an array substrate and includes gate lines arranged in a transverse direction and data lines arranged in a longitudinal direction perpendicular to the gate lines. A pixel electrode is formed on a region of the lower substrate defined by the gate and data lines. Thin film transistors (TFTs) are formed as switching elements at a crossing point of the gate and data lines in a matrix. Each of the TFTs includes a gate electrode, a source electrode and a drain electrode. The drain electrode contacts the pixel electrode via a drain contact hole. Peripheral portions of the two substrates are sealed by a sealant to prevent liquid crystal leakage. The gate lines serve to transmit scanning signals to the gate electrodes, and the data lines serve to transmit data signals to the source electrodes. The data signals change alignments of the liquid crystal molecules according to the scanning signals such that the LCD device displays various gray levels.
In such an LCD device, a driver integrated circuit (IC) that applies signals to each electrode through each line on the lower substrate may be mounted using various methods, for example, chip on board (COB), chip on glass (COG), tape carrier package (TCP), and the like.
The COB method is conventionally adopted for a segment type LCD device, or a LCD panel having a low resolution. Since the segment type LCD device or the low resolution LCD panel uses a small number of leads, the driver IC thereof has also a small number of leads. Therefore, the driver IC thereof is first installed on a printed circuit board (PCB) having a plurality of leads, and the leads of the PCB are connected with the LCD panel via a proper method, which is relatively simple.
However, as the LCD devices have high resolutions, a great number of leads are adopted for the driver IC. When the driver IC has a great number of leads, it is difficult to install the driver IC on the above-mentioned PCB.
In another method, the COG method, the driver IC is directly installed on the LCD panel without interposing the PCB. Therefore, the connection between the driver IC and the LCD panel is stable, and a minute pitch is applicable for the installation of the driver IC. The COG method employs a multi-layered flexible printed circuit board (FPCB) instead of the PCB. The multi-layered FPCB contacts the LCD panel via an anisotropic conductive film (ACF) and transmits input signals to the driver IC.
The above-mentioned COG method has advantages of low cost and high stability. However, since a pad of the LCD panel needs an additional area to install the driver IC, the LCD panel should be enlarged. In addition, when the COG method is adopted for the LCD panel, it is difficult to repair defects of the driver IC or terminal lines of the LCD panel.
In another method, the TCP method, the driver IC is installed on a polymer film. The TCP method is widely used for LCD devices as well as mobile phones that need small, thin, and light electrical packages.
FIG. 1
is a cross-sectional view illustrating a liquid crystal panel having a driver IC mounted thereon using the TCP technique. As shown in
FIG. 1
, a driver IC
17
is mounted on a polymer film
19
, and the polymer film
19
having the driver IC
17
is connected with both a lower substrate
11
and a printed circuit board
15
through an anisotropic conductive film (ACF)
18
. Signals are applied through such a tape carrier package from one or each end portion of gate and data lines (not shown) in order to drive the liquid crystal panel having the lower and upper substrates
11
and
13
.
FIG. 3
is a plan view illustrating a conventional quad type color LCD device. A liquid crystal panel
111
generally includes a number of dots, and each unit pixel includes four sub-pixels or dots: an RGBW (red, green, blue, and white) arrangement as shown in
FIG. 3
or an RGGB (red, green, green, and blue) arrangement (not shown).
In a large-sized LCD device employing the TFT as a switching element, when a direct current bias is applied to the liquid crystal layer, the liquid crystal layer can deteriorate. Thus, it is preferable to change a polarity of a voltage applied to the liquid crystal layer for each frame. Such inversion driving methods are classified into frame inversion, column inversion, line inversion, and dot inversion.
FIGS. 2A
to
2
D are plan views illustrating the four inversion methods mentioned above. In the frame inversion driving method, as shown in
FIG. 2A
, all of the sub-pixels receive signals of the same polarity in one frame and in next frame all of the sub-pixels receive signals of inverse polarity.
FIG. 2B
illustrates the column inversion driving method, that sub-pixels of every other column receive the signals of the same polarity and the polarity of the signal is changed at the next frame.
FIG. 2C
illustrates the line inversion driving method, that sub-pixels of every other line (row direction) receive the signals of the same polarity and the polarity of the signal is changed at the next frame.
FIG. 2D
illustrates the dot inversion driving method. In the dot inversion drive method, the drive voltages applied to the pixel electrodes are such that the polarities of two adjacent pixel electrodes, which are disposed adjacent to each other in either the column or row direction, are opposite to each other with respect to the counter electrode. In other words, the polarities of the pixel electrodes with respect to the counter electrodes alternate as viewed along both the column direction and the row direction in each instance.
Through such inversion methods, cross talk and flickering of a screen can be reduced and a large-sized color LCD device is driven using such a method.
In order to drive the LCD device, gate driver ICs and data driver ICs, which are respectively connected with data lines and gate lines, are mounted to the liquid crystal panel through various method described above. Further, the LCD device employs either a dual bank structure or a single bank structure to drive the liquid crystal layer. In the dual bank structure, the data driver ICs are arranged on both top and bottom side portions of the liquid crystal panel, or the gate driver ICs are arranged on both right and left side portions of the liquid crystal panel. In the single bank structure, the data driver ICs are all arranged on either the top or the bottom portion of the liquid crystal panel, or the gate driver ICs are all arranged on either the right or left portion of the liquid crystal panel.
As shown in
FIG. 3
, the liquid crystal panel
111
adopts the dual bank structure that has a plurality of the driver ICs at all four sides of the liquid crystal panel. Namely, the data driver ICs
115
a
and
115
b
that apply the data signals to the data lines
119
are arranged on both top and bottom portion of the liquid crystal panel
111
, and the gate driver ICs
113
a
and
113
b
that apply the scanning signals to the gate lines
117
are arranged on both left and right side portions of the liquid crystal panel
111
. For a more detailed explanation, the two gate driver ICs
113
a
are arranged on a left side portion of the liquid crystal panel
111
, and two gate driver ICs
113
b
are arranged on a right side portion of the liquid crystal panel
111
in the dual bank structure. Also, the four data driver ICs
115
a
are arranged in the top portion of the
Chung In-Jae
Song In-Duk
Chowdhury Tarifur R.
LG.Philips LCD Co. , Ltd.
McKenna Long & Aldridge LLP
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