Liquid crystal cells – elements and systems – Particular structure – Having significant detail of cell structure only
Reexamination Certificate
1998-11-25
2001-03-27
Malinowski, Walter J. (Department: 2871)
Liquid crystal cells, elements and systems
Particular structure
Having significant detail of cell structure only
C349S110000, C349S187000
Reexamination Certificate
active
06208394
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a liquid crystal display device used for displays of office automation apparatuses, audio and video apparatuses, and the like, and a method for fabricating such a liquid crystal display device.
2. Description of the Related Art
A conventional transistor-type active matrix driven liquid crystal display device will be described with reference to
FIGS. 6A and 6B
, as the first prior art example.
FIG. 6A
is a perspective view of the conventional liquid crystal display device, and
FIG. 6B
is a sectional view taken along line
6
B—
6
B of FIG.
6
A.
Referring to
FIG. 6B
, the conventional liquid crystal display device includes a first substrate
601
(hereinbelow, referred to as a counter substrate) and a second substrate
602
(hereinbelow, referred to as an active matrix substrate) disposed to face each other with a predetermined gap therebetween. A liquid crystal layer
612
is provided between the substrates
601
and
602
. Referring to
FIG. 6A
, the active matrix substrate
602
includes: a plurality of parallel source bus lines
609
and a plurality of parallel gate bus lines
610
which are formed on the surface of a glass substrate
620
facing the liquid crystal layer
612
; and thin film transistors (TFTs)
611
disposed at the respective crossings of the source bus lines
609
and the gate bus lines
610
. Pixel electrodes
608
are formed on the surface of the glass substrate
620
facing the liquid crystal layer
612
and connected to drain electrodes of the corresponding TFTs
611
. A voltage is applied to each of the pixel electrodes
608
for controlling the orientation direction of liquid crystal molecules in the liquid crystal layer
612
.
Referring to
FIG. 6B
, the counter substrate
601
includes: a plurality of colored portions
605
on the surface thereof facing the liquid crystal layer
612
at positions corresponding to the pixel electrodes
608
of the active matrix substrate
602
; and a counter electrode
603
formed covering the colored portions
605
. A black matrix (BM) layer
604
made of a light-blocking material is disposed to fill gaps between the adjacent colored portions
605
.
Hereinbelow, a color filter layer as used herein will be described. For example, when pixels are arranged in a strip shape, stripe-shaped colored portions of red (R), green (G), and blue (B) are arranged cyclically in parallel. A color layer is composed of a plurality of stripe-shaped color portions of a single color or a plurality of colored portions of a single color corresponding to respective pixel electrodes. Such color layers constitute a color filter layer. The color filter layer as used herein does not include the BM layer formed between the adjacent colored portions. Herein, a region of the liquid crystal display device defined by each of the pixel electrodes is called a pixel region.
Referring back to
FIGS. 6A and 6B
, in the conventional liquid crystal display device, a scanning signal voltage is sequentially applied to the gate bus lines
610
so as to switch on the TFTs
611
connected to the respective gate bus lines
610
, thereby allowing a specific display signal voltage to be written in each of the pixel electrodes
608
and held for a certain time period. The liquid crystal layer
612
interposed between the substrates
601
and
602
is driven with the potential difference between the voltage at each of the pixel electrodes
608
and a counter voltage applied to the counter electrode
603
.
Two exemplary methods normally used for fabricating the counter substrate having a plurality of colored portions as described above will be described with reference to
FIGS. 7A
to
7
E and
8
A to
8
E.
FIGS. 7A and 8A
are flowcharts showing normal fabrication steps for the counter substrate having colored portions.
FIGS. 7B
to
7
D and
8
B to
8
D are plan views, together with corresponding sectional views, at the respective fabrication steps.
FIGS. 7E and 8E
are sectional views of the respective complete counter substrates.
Herein, a normal dry film fabrication method will be described with reference to
FIGS. 7A
to
7
E. A resin film (dry film) having red (R) pigments dispersed therein is laminated to a glass substrate
720
, followed by steps such as exposure to light, development, and baking, to form an R color layer composed of a plurality of stripe-shaped R colored portions
705
.
A dry film having green (G) pigments dispersed therein is then laminated to substantially the entire top entire top surface of the resultant substrate to form a counter electrode
703
. Thus, a counter substrate
701
is fabricated. As the BM layer, a metal film may also be used as shown in
FIG. 8B
as a metal BM film
804
.
FIGS. 8A
to
8
E illustrate a fabrication process of the counter substrate by a spin coat method. Resin materials having color pigments dispersed therein are applied to substantially the entire top surface of a glass substrate
820
by spin coating, to form R, G, and B colored portions
805
,
806
, and
807
, so as to fabricate a counter substrate
801
.
Hereinbelow, a common transfer portion formed in a conventional liquid crystal display device such as described above will be described with reference to
FIGS. 9A
to
9
C. The common transfer portion as used herein refers to a portion for securing an electrical connection between the counter substrate and the active matrix substrate to be used as a terminal formed on the active matrix substrate for applying a voltage to the counter electrode.
FIG. 9A
is a plan view, together with a corresponding sectional view, of a conventional liquid crystal display device.
FIG. 9B
is a plan view, together with a corresponding sectional view, illustrating a common transfer portion of an active matrix substrate
902
of the conventional liquid crystal display device. In
FIG. 9B
, the reference numerals
909
and
910
denote source bus lines and gate bus lines, respectively.
FIG. 9C
is a plan view, together with a corresponding sectional view, illustrating a common transfer portion of a counter substrate
901
of the conventional liquid crystal display device. In
FIG. 9C
, the reference numeral
905
denotes colored portions.
Referring to
FIG. 9B
, the active matrix substrate
902
includes a common transfer electrode
917
formed between adjacent source driver connection blocks in a source terminal extension portion. The common transfer electrode
917
is connected to a common line at a position on the periphery of the display panel, and is electrically connected with a counter electrode
903
(
FIG. 9C
) of the counter substrate
901
via carbon paste
918
. The number of such common transfer electrodes
917
formed for one display panel may be appropriately determined depending on the definition level of the panel, the size of the panel, the difference in resistance from the transparent counter electrode, and the like. For example, for a panel equivalent to Type 10 VGA, about four to eight common transfer electrodes are normally provided.
Referring to
FIG. 9C
, in the counter substrate
901
, ITO is deposited using a mask so that an ITO portion
903
is formed on the area of the counter substrate
901
corresponding to the common transfer electrode
917
of the active matrix substrate
902
, so that the ITO portion
903
comes into contact with the carbon paste
918
of the active matrix substrate
902
. The resultant connection portion of the counter substrate
901
has a structure of a glass substrate
920
/a BM layer
904
/the ITO portion
903
/the carbon paste
918
formed in this order. Alternatively, ITO may be formed over the entire surface of the counter substrate
901
, instead of masking. In this case also, the same structure as described above is obtained.
The counter substrate
901
and the active matrix substrate
902
fabricated as described above are placed to face each other with a predetermined gap therebetween. While a sealer
919
is provided between the substrates
901
and
902
along t
Tanaka Keiichi
Yamamoto Tomohiko
Malinowski Walter J.
Nixon & Vanderhye P.C.
Sharp Kabushiki Kaisha
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