Liquid crystal cells – elements and systems – Particular structure – Having significant detail of cell structure only
Reexamination Certificate
1999-11-04
2001-10-23
Sikes, William L. (Department: 2871)
Liquid crystal cells, elements and systems
Particular structure
Having significant detail of cell structure only
C349S044000, C349S110000
Reexamination Certificate
active
06307613
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a liquid crystal display panel, and more particularly to an active matrix type liquid crystal display panel provided with an alignment checking mark for checking alignment of a first polarizer with respect to its corresponding substrate in the liquid crystal display panel.
2. Description of the Related Art
In general, the liquid crystal display panel is constructed of: a glass substrate (hereinafter referred to as the TFT substrate) provided with a plurality of thin film transistors (hereinafter referred to as the TFTs); another glass substrate (hereinafter referred to as the CF substrate) provided with a color filter (hereinafter referred to as the CF substrate); a liquid crystal layer sandwiched between the TFT substrate and the CF substrate; and, a pair of polarizers each of which is applied to each of the TFT substrate and the CF substrate. In fabricating such a liquid crystal display panel, it is necessary for each of the polarizers to be precisely aligned in position with each of the TFT substrate and the CF substrate. Further, in order to keep constant in production quality the liquid crystal display panel, it is necessary to check alignment of the polarizer after completion of its application to each of the TFT substrate and the CF substrate. Further, in order to improve the liquid crystal display panel both in production quality and in productivity, it is important to check alignment of the polarizer precisely and in a speedy manner.
Heretofore, checking alignment of the polarizer and the CF substrate has been performed with reference to a side edge of the CF substrate and its corresponding side edge of the polarizer. In other words, by using the polarizer which is similar to the CF substrate in shape but slightly smaller in size than the CF substrate (for example, by the amount of from 1 to 0.5 mm in each side), a gap in each side between the CF substrate and the corresponding polarizer is visually checked. In the case that the CF plate and the polarizer are precisely aligned with each other, the same gap is observed in every side. Consequently, with respect to the CF substrate, it is possible to visually check alignment of the polarizer with practically allowable accuracy.
In contrast with the above, it is not possible to perform an alignment operation of the polarizer with respect to the TFT substrate in the same manner as that described above, because: in general, the TFT substrate is provided with a terminal region for mounting therein a drive IC circuit (i.e., Integrated Circuit serving as a drive circuit), and therefore larger in size than the CF substrate in plan view by the amount of the corresponding area of such terminal region. As for a display area of the liquid crystal display panel, there is substantially no difference between the TFT substrate and the CF substrate. As a result, the terminal region of the TFT substrate is placed off a side edge line of the CF substrate in plan view. Further, in order to avoid interface between the liquid crystal display panel and a mechanism element of a module in which the liquid crystal display panel is mounted, the polarizer of the liquid crystal display panel is restricted in plan view to a plane size larger than the display area of the liquid crystal display panel by the amount of from approximately 1 to approximately 2 mm in each of width and height. In this case, even when the alignment operation of the polarizer and the TFT substrate is precisely performed, a gap between the side edge of the TFT substrate and the corresponding side edge of the polarizer varies in each of side edges of the TFT substrate (for example, within a range of from 1 to 5 mm). Consequently, as for the TFT substrate, it is difficult to visually check alignment of the polarizer and the TFT substrate in the same manner as that used in the case of the CF substrate.
On the other hand, Japanese Patent Laid-Open No. Hei 5-216021 discloses a conventional liquid crystal display panel which is capable of checking alignment of a substrate and a polarizer with the use of an alignment checking mark.
FIG. 7
shows an exploded perspective view of the conventional liquid crystal display panel disclosed in this Japanese Patent Laid-Open No. Hei 5-216021 (hereinafter referred to the prior art 1).
As is clear from
FIG. 7
, this conventional liquid crystal display panel is constructed of: a glass substrate (hereinafter referred to as the TFT substrate)
101
provided with a plurality of thin film transistors (i.e., TFT not shown); another glass substrate (hereinafter referred to as the CF substrate) provided with a color layer (i.e., CF layer)
109
; a liquid crystal layer sandwiched between these substrates
101
and
109
; and, a pair of polarizers
102
,
107
.
The plurality of the TFTs are arranged in a matrix on a surface
101
a
of the TFT substrate
101
, in which a plurality of pixel electrodes (not shown) are electrically connected with these TFTs. The plurality of the pixel electrodes and the TFTs are combined to form a pixel group region
108
shown in gray in FIG.
7
. Further formed on the surface
101
a
of the TFT substrate
101
are: a plurality of scanning lines (not shown) for feeding a selection signal to each of the TFTs; and, a plurality of signal lines (not shown) for feeding a video signal to each of the TFTs.
In the surface
101
a
of the TFT substrate
101
, formed outside the pixel group region
108
are three common electrode wiring layers
104
a,
104
b
and
104
c.
As is clear from
FIG. 7
, each of the common electrode wiring layers
104
a,
104
b
assumes an inverted L-shaped form in plan view, while the remaining common electrode wiring layer
104
c
assumes a U-shaped form in plan view. A predetermined voltage is supplied from an external source to each of these common electrode wiring layers
104
a,
104
b
and
104
c.
A transfer electrode
110
is formed in each of these common electrode wiring layers
104
a,
104
b
and
104
c
and electrically connected with these wiring layers
104
a,
104
b
and
104
c.
The polarizer
102
is aligned with and mounted in its mounting area
130
(shown in dotted lines in
FIG. 7
) which is defined in a rear surface
101
b
of the TFT substrate
101
. The polarizer
102
is larger in size than the pixel group region
108
in plan view to cover the entire pixel group region
108
from the rear surface (
101
b
) side of the TFT substrate
101
.
Formed in a rear surface
106
b
of the CF substrate
106
is a color filter (i.e., CF) layer
109
, which comprises: respective pigment dots or strips of R (i.e., red), G (i.e., green), and B (i.e., Blue) colors each arranged in a predetermined pattern; and, a black matrix (not shown) arranged so as to fill a space between these pigment dots or strips of R, G, and B colors, the black matrix being made of light shielding metal or black resins. The CF layer
109
defines a display region
111
in the above conventional liquid crystal display panel.
Integrally formed with the black matrix (not shown) around the outside of the CF layer
109
is a belt-like light shielding layer
105
. Formed further outside the light shielding layer
105
are eight pairs of alignment checking marks
103
, which are made of the same material as that of the light shielding layer
105
and disposed in four corners of the CF substrate
106
.
Formed in surfaces of both the CF layer
109
and the light shielding layer
105
are common electrodes (not shown), each of which is made of transparent and electrically conductive material to cover the entire area of the rear surface
106
b
of the CF substrate including the alignment checking marks
103
. The common electrodes (not shown) are electrically connected with the transfer electrodes
110
. A predetermined voltage is supplied from each of the common electrode wiring layers
104
a,
104
b
and
104
c
to the corresponding one of the common electrodes (not shown) through the corresponding one of the transfer electrodes
110
.
On the oth
Chowdhury Tarifur R.
McGinn & Gibb PLLC
NEC Corporation
Sikes William L.
LandOfFree
Liquid crystal display panel with plurality of alignment... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Liquid crystal display panel with plurality of alignment..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Liquid crystal display panel with plurality of alignment... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2603382