Liquid crystal cells – elements and systems – Particular structure – Holder – support – frame – or housing
Reexamination Certificate
2002-12-26
2004-12-07
Kim, Robert H. (Department: 2871)
Liquid crystal cells, elements and systems
Particular structure
Holder, support, frame, or housing
C118S728000, C118S500000, C427S455000
Reexamination Certificate
active
06829022
ABSTRACT:
This application claims the benefit of Korean Patent Application No. 2001-0088755, filed on Dec. 31, 2001, 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 chuck for an exposure apparatus that is used in forming a liquid crystal display (LCD) device, especially an in-plane switching mode liquid crystal display (IPS-LCD) device.
2. Description of the Related Art
A liquid crystal display device uses the optical anisotropy and polarization properties of liquid crystal molecules to produce an image. Liquid crystal molecules have a definite alignment direction as a result of their long, thin shapes. That alignment direction can be controlled by an applied electric field. In other words, as an applied electric field changes, so does the alignment of the liquid crystal molecules. Due to the optical anisotropy, the refraction of incident light depends on the alignment direction of the liquid crystal molecules. Thus, by properly controlling an applied electric field a desired image can be produced.
Of the different types of known LCDs, active matrix LCDs (AM-LCDs), which have thin film transistors and pixel electrodes arranged in a matrix form, are the subject of significant research and development because of their high resolution and superiority in displaying moving images.
LCD devices have wide application in office automation (OA) equipment and video units because they are light and thin and have low power consumption characteristics. The typical liquid crystal display (LCD) panel has an upper substrate, a lower substrate and a liquid crystal layer interposed therebetween. The upper substrate, commonly referred to as a color filter substrate, usually includes a common electrode and color filters. The lower substrate, commonly referred to as an array substrate, includes switching elements, such as thin film transistors (TFTs) and pixel electrodes.
As previously described, LCD device operation is based on the principle that the alignment direction of the liquid crystal molecules is dependent upon an electric field applied between the common electrode and the pixel electrode. Thus, the alignment direction of the liquid crystal molecules is controlled by the application of an electric field to the liquid crystal layer. When the alignment direction of the liquid crystal molecules is properly adjusted, incident light is refracted along the alignment direction to display image data. The liquid crystal molecules function as an optical modulation element having variable optical characteristics that depend upon polarity of the applied voltage.
FIG. 1
shows a schematic exploded perspective view illustrating an LCD device according to a related art. The LCD device
11
includes an upper substrate
5
and lower substrate
22
that are spaced apart and face each other, and a liquid crystal layer
14
interposed therebetween. The upper substrate
5
and the lower substrate
22
are called a color filter substrate and an array substrate, respectively. On the rear surface of the upper substrate
5
, a black matrix
6
and a color filter layer
8
, including a plurality of red (R), green (G) and blue (B) color filters, are formed. The black matrix
6
surrounds each color filter forming an array matrix. The upper substrate
5
also includes a common electrode
18
covering the color filter layer
8
and the black matrix
6
. The common electrode
18
is preferably made of a transparent conductive material.
On the front surface of the lower substrate
22
, thin film transistors (TFTs) T acting as switching elements, are formed in the shape of an array matrix corresponding to the color filter layer
8
. In addition, a plurality of gate and data lines
13
and
15
cross each other such that each TFT is positioned near each crossing of the gate and data lines
13
and
15
. Each individual pair of gate and pair of data lines
13
and
15
define a pixel region P. In the pixel region P, a pixel electrode
17
is disposed. The pixel electrode
17
is formed of a transparent conductive material, such as indium tin oxide, which has an excellent transmissivity.
The LCD device having the above-mentioned structure displays color images by applying signals through the TFTs T to the pixel electrodes
17
. The gate line
13
applies a first signal to a gate electrode of the TFT T, and the data line
15
applies a second signal to a source electrode of the TFT T. Therefore, the LCD device drives the liquid crystal molecules using their electro-optic characteristics.
The liquid crystal layer
14
is a dielectric anisotropic material having spontaneous polarization characteristics. Due to their dipole and spontaneous polarization when electric signals are applied to the pixel electrode
17
and to the common electrode
18
, the liquid crystal molecules of the liquid crystal layer
14
are rearranged in accordance with the electric field. As the liquid crystal molecules are rearranged, the optical property of the liquid crystal layer changes, creating an electro-optic modulation effect.
In the LCD device of the related art shown in
FIG. 1
, since the pixel and common electrodes are positioned on the lower and upper substrates, respectively, the electric field induced between them is perpendicular to the lower and upper substrates. However, the above-described LCD devices having the longitudinal electric field have a drawback in that they have a very narrow viewing angle. In order to solve the problem of narrow viewing angle, in-plane switching liquid crystal display (IPS-LCD) devices have been proposed. The IPS-LCD devices typically include a lower substrate where a plurality of pixel electrodes and common electrodes are disposed, an upper substrate having no electrode, and a liquid crystal interposed between the upper and lower substrates. A detailed explanation about the lower substrate (i.e., array substrate) of the IPS-LCD device will be provided referring to figures.
FIG. 2
is a schematic plan view illustrating one pixel of an array substrate of an in-plane switching mode liquid crystal display (IPS-LCD) device according to a related art. As shown, gate lines
32
and a common line
36
are arranged parallel to each other, and data lines
44
are arranged perpendicular to the gate and common lines
32
and
36
. A pair of gate and a pair of data lines
32
and
44
define a pixel region P. A thin film transistor (TFT)
41
that is connected to the gate and data lines
32
and
44
is disposed at a crossing portion of the gate and data lines
32
and
44
. The common line
36
transversely crosses the pixel region, and a plurality of common electrodes
38
are disposed perpendicular to the common line
36
and connected thereto at a center of the pixel region. The plurality of common electrodes
38
are spaced apart from each other with a predetermined interval therebetween.
A plurality of pixel electrodes
50
are disposed parallel to the data line
44
and connected to a pixel connecting line
51
, which is disposed above the gate line
32
. Since the pixel connecting line
51
overlaps a portion of the gate line
32
, the pixel connecting line
51
and the portion of the gate line
32
constitute a storage capacitor S. Namely, the pixel connecting line
51
acts as a first electrode of the storage capacitor S, while the portion of the gate line
32
acts as a second electrode of the storage capacitor S.
Furthermore, one of the pixel electrodes
50
is electrically connected with the TFT
41
. The plurality of common electrodes
38
and the pixel electrodes
50
are spaced apart from each other with a predetermined interval therebetween and arranged in an alternating pattern. Therefore, each common electrode
38
is parallel to an adjacent pixel electrode
50
.
The TFT
41
includes a gate electrode
34
, an active layer
40
, a source electrode
46
and a drain electrode
48
. The gate electrode
34
is a portion of the gate line
32
; the source electrode
46
extends from the
Kim Robert H.
LG.Philips LCD Co. , Ltd.
McKenna Long & Aldridge LLP
Qi Mike
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