Liquid crystal cells – elements and systems – Nominal manufacturing methods or post manufacturing... – Defect correction or compensation
Reexamination Certificate
1999-04-28
2001-05-29
Dudek, James A. (Department: 2871)
Liquid crystal cells, elements and systems
Nominal manufacturing methods or post manufacturing...
Defect correction or compensation
Reexamination Certificate
active
06239856
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to a liquid crystal panel having an image display function and a method of manufacturing the same.
BACKGROUND OF THE INVENTION
Owing to the recent progress in micro-processing technology, liquid crystal material technology and mounting technology, liquid crystal panels of 5 to 50 cm in diagonal size are commercially presented as practicable display devices of television image and various images. Color display is also realized easily by forming coloring layers of R, G, B in one of the two glass substrates for composing a liquid crystal panel. In particular, in the so-called active type liquid crystal panel having switching elements incorporated in each pixel, images of small crosstalk, fast response, and high contrast ratio are guaranteed.
In such liquid crystal panels, the matrix is generally composed of 100 to 1,000 scanning lines and 200 to 2,000 signal lines, but lately trends for larger screen size and higher definition are promoted simultaneously.
FIG. 8
shows a mounting state on a liquid crystal panel in a prior art. This liquid crystal panel
1
is realized by various mounting methods, such as COG (chip on glass) method in which a semiconductor integrated circuit chip
3
for supplying drive signals is directly connected to an electrode terminal group
6
of scanning lines formed on one transparent insulating substrate (for example, glass substrate)
2
, or TCP (tape carrier package) method in which a TCP film
4
having terminals (not shown) of gold-plated copper foils are fixed to a terminal group
5
of signal lines by pressing with an adequate adhesive containing a conductive medium, using, for example, a polyimide resin thin film as the base, and therefore electric signals are supplied into the image display unit. In the drawing, two mounting methods are shown simultaneously, but actually either method is selected appropriately.
Reference numerals
7
and
8
are wiring routes for connecting between the image display unit of the liquid crystal panel
1
and electrode terminal groups
5
and
6
of signal lines and scanning lines, and they may not be always composed of same conductive materials as the electrode terminal groups
5
and
6
.
Reference numeral
9
is other transparent insulating substrate (for example, glass substrate) having a counter electrode of transparent conductivity common to all liquid crystal cells. Two substrates
200
and
900
for composing the liquid crystal panel
1
are disposed at a specified gap of about several microns through a spacer member such as resinous fiber or bead. This gap is a closed space as being closed by a seal member and a stopping member made of organic resin in the peripheral parts of the substrates
200
,
900
, and this closed space is filled with liquid crystal.
To realize a color display, generally, the closed space side of the glass substrate
9
is coated with an organic thin film in a thickness of about 1 to 2 &mgr;m containing either one or both of dye and pigment called coloring layer, and a color display function is provided, and in such a case the color substrate
900
is particularly called “color filter substrate.” Depending on the properties of liquid crystal material, a polarizer is adhered to either one or both of the upper surface of the glass substrate
9
and the lower surface of the glass substrate
2
, and the liquid crystal panel
1
functions as an electro-optic element. A general twisted nematic (TN) liquid crystal requires two polarizers.
FIG. 9
is an equivalent circuit diagram of an active type liquid crystal panel having, for example, thin film insulating gate type transistors disposed at each pixel as conventional switching elements. Elements indicated by solid line are switching elements formed on one glass substrate
2
, and compose the active substrate
200
, and elements indicated by broken line are formed on other glass substrate
9
, and compose the color filter substrate
900
. Scanning lines
11
(
8
) and signal lines
12
(
7
) are formed on the active substrate
200
simultaneously when forming a TFT (thin film transistor)
10
using, for example, amorphous silicon as semiconductor layer and silicon nitride layer as gate insulating layer.
Liquid crystal cells
13
are composed of transparent conductive pixel electrodes
14
(see
FIG. 10
) formed on the active substrate
200
, transparent conductive counter electrodes
15
formed on the color filter substrate
900
, and liquid crystal
16
(see
FIG. 10
) contained in the closed space formed between the two substrates
200
and
900
, and electrically they are equivalent to capacitors. The constitution of storage capacity for increasing the time constant of the liquid crystal cells
13
may be realized by several methods. In
FIG. 9
, for example, a storage capacity
17
is composed by inserting an insulating layer such as gate insulating layer of TFT
10
between common electrodes
18
common to all pixel electrodes
14
and the pixel electrodes
14
.
FIG. 10
is a sectional view showing essential parts of an active type color liquid crystal panel. Coloring layers
19
composed of stained photosensitive gelatin or coloring photosensitive resin are disposed in a specified arrangement in three primaries of R, G, B, corresponding to the pixel electrodes
14
, at the closed space side of the color filter substrate
900
. Counter electrodes
15
common to all pixel electrodes
14
are formed on the coloring layers
19
in order to avoid loss of voltage distribution in the liquid crystal cells due to interposition of the coloring layers
19
. Orientation films (for example, polyimide resin thin film layers in a film thickness of about 0.1 &mgr;m)
20
applied on the two substrates
200
,
900
, contacting with the liquid crystal
16
are intended to align the liquid crystal molecules in a specified direction. Thus, when the twisted nematic (TN) type is used as the liquid crystal
16
, upper and lower polarizers
21
are needed.
When opaque films
22
of low reflectivity are arranged in the boundaries of R, G, B coloring layers
19
, reflected light from the wiring layers such as signal lines
12
on the active substrate
200
can be prevented, and therefore the contrast ratio of the image is enhanced. It is also possible to prevent increase of leak current during OFF operation due to external light irradiation of the TFT
10
which is a switching element,
80
that the liquid crystal panel can be operated even under an intense external light. This is already realized as black matrix (BM).
Various examples may be also considered for the composition of the black matrix (BM). From the viewpoint of cost, it is not advantageous in consideration of occurrence of step in the boundaries of adjacent coloring layers
19
and transmissivity of light, therefore, it is easy and rational to use metal thin films in a film thickness of about 0.1 &mgr;m, for example, Cr thin films, as the opaque films
22
.
In
FIG. 10
, meanwhile, in addition to the TFT
10
, scanning lines
11
and storage capacity
17
, other constituent elements such as back light source and spacer are omitted. Reference numeral
23
is a conductive thin film for connecting between the pixel electrodes
14
and the drain of the TFT
10
. This conductive thin film
23
is generally formed simultaneously by the same material as the signal lines
12
, and is called a drain wiring (electrode). Although not shown in the drawing, the counter electrode
15
is connected to a proper conductive pattern on the active substrate
200
having the TFT
10
, through an appropriate conductive paste on the outer circumference slightly outside of the image display unit, and is incorporated in part of the electrode terminal groups
5
,
6
(see
FIG. 8
) so as to be connected electrically.
The liquid crystal cells in this liquid crystal panel are composed of transparent conductive pixel electrodes formed on one substrate
200
, similar counter electrodes on the color filter substrate
900
, and liquid crystal contained in the clearance between
Imura Hideyuki
Kawasaki Kiyohiro
Dudek James A.
Matsushita Electric - Industrial Co., Ltd.
Parkhurst & Wendel LLP
LandOfFree
Liquid crystal panel and its manufacturing method 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 panel and its manufacturing method, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Liquid crystal panel and its manufacturing method will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2562388