Liquid crystal cells – elements and systems – Particular structure – Having significant detail of cell structure only
Reexamination Certificate
2001-02-26
2004-08-10
Chowdhury, Tarifur R. (Department: 2871)
Liquid crystal cells, elements and systems
Particular structure
Having significant detail of cell structure only
C349S155000, C349S123000, C349S138000, C349S110000
Reexamination Certificate
active
06774975
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to a liquid crystal display panel, and more particularly to a liquid crystal display panel wherein a lower substrate provided with a thin film transistor array has a constant distance from an upper substrate provided with color filters.
2. Description of the Related Art
Generally, a liquid crystal display (LCD) panel consists of a lower transparent substrate, an upper transparent substrate and a liquid crystal injected into a space defined by an adhesion of the upper transparent substrate to the lower transparent substrate.
In the lower transparent substrate, a pixel array in which a plurality of thin film transistors each consists of a gate electrode, a gate insulating film, an active layer, an ohmic contact layer, source and drain electrodes is electrically connected to a pixel electrode to make each pixel. Also, a driving circuit is formed or installed on the lower transparent substrate. In the upper transparent substrate, color filters and black matrices used as light-shielding layers are formed.
In a fabricating process of the LCD panel, the lower substrate and the upper substrate are manufactured by a separate process. Then, the lower substrate and the upper substrate are adhered to each other by a sealant such that the pixel electrodes of the lower substrate are opposed to the color filters of the upper substrate at a desired distance to define a space. A liquid crystal is injected into this space.
FIG. 1
is a planar view showing a lower substrate of a conventional liquid crystal panel, and
FIG. 2
is a sectional view showing a structure of a conventional LCD panel, which includes the lower substrate of
FIG. 1
, across line A-A′ of FIG.
1
.
Referring to
FIGS. 1 and 2
, the conventional LCD panel consists of a lower substrate
10
, an upper substrate
40
and a liquid crystal
45
filled in a space between the lower substrate
10
and the upper substrate
40
.
The lower substrate
10
includes: a gate line
15
; a data line
26
; a thin film transistor positioned at a intersection of the gate line
15
with the data line
26
; a pixel electrode
31
formed in a pixel area defined by crossing the gate and data lines
15
and
26
; a spacer
43
on the intersection of the gate line
15
with the data line
26
for maintaining a constant distance between the upper and lower substrates The thin film transistor consisting of a gate electrode
13
, a gate insulating film
17
, an active layer
19
, an ohmic contact layer
21
and source and drain electrodes
23
and
25
formed on a first transparent substrate
11
. The gate electrode
13
is connected to a date line
15
, and the source electrode
23
is connected to a data line
26
.
A protective layer
27
covering the thin film transistors having the above-mentioned structure are formed on the gate insulating film
17
, and a contact hole
29
exposing the drain electrode
25
is defined at this protective layer
27
. On the protective layer
27
are provided a transparent pixel electrode
31
being in contact with and electrically connected to the drain electrode via the contact hole
29
. Also, a first alignment film
33
covering a pixel electrode
31
is formed on the protective layer
27
.
The upper substrate
40
has a black matrix
37
and color filters (not shown) formed on a second transparent substrate
35
. The black matrix
37
is formed at a portion corresponding to the thin film transistor of the lower substrate, or a portion corresponding to the gate line
15
and the data line
26
including said portion corresponding to the thin film transistor. The color filters are formed in correspondence with the pixel electrode to filter and pass red(R), green(G) and blue(B) lights. A transparent common electrode
39
are formed at the front side of the second transparent substrate
35
, and a second alignment film
41
is formed on this common electrode
39
.
The lower substrate
10
and the upper substrate
40
are adhered to each other such that the thin film transistor is opposed to the black matrix
37
. In this case, a spacer
43
for allowing the lower substrate
10
to have a constant distance from the upper substrate is provided. The spacer
43
is made from an organic insulating material. The spacer
43
is formed at an intersection between the gate line
15
and the data line
26
of the data line
26
of the lower substrate
10
to constantly keep a distance between the lower substrate
10
and the upper substrate
40
. The spacer
43
may be formed at the lower substrate
10
or the upper substrate
40
. A liquid crystal
45
is injected a space made by an adhesion of the lower substrate
10
to the upper substrate
40
.
As described above, the conventional LCD panel has constantly keep a space between the lower substrate and the upper substrate adhered to each other by means of the spacer formed at an intersection between the gate line and the data line of the lower substrate or the upper substrate.
However, the conventional LCD panel has a problem in that, since the lower substrate requires a spacer for constantly keeping a space between the lower substrate adhered to the protective layer protecting the thin film transistor and the upper substrate and the upper substrate requires a black matrix for shutting off a light, its structure and its fabricating process become complex. Also, the conventional LCD panel has a problem in that, since it is necessary to define a contact hole for connecting the pixel electrode to the drain electrode, its fabricating process becomes complex
SUMMARY OF THE INVENTION
Accordingly, it is an object of the present invention to provide a liquid crystal display panel wherein a space between a lower substrate and an upper substrate can be constantly kept by means of a protective film pattern.
Another object of the present invention is to provide a liquid crystal display panel wherein an upper substrate thereof does not require a block matrix for shielding a light.
In order to achieve these and other objects of the invention, a liquid crystal display panel according to one aspect of the present invention includes: a first substrate and a second substrate spaced from and facing to each other to have a gap therebetween; a liquid crystal layer between the first and second substrate; a thin film transistor formed on the first substrate, the thin film transistor having a semiconductor pattern, a source electrode and drain electrode, a portion of the semiconductor pattern being exposed between the source electrode and the drain electrode; and a patterned spacer formed on the thin film transistor and supporting the second substrate, the patterned spacer having an insulating layer on the bottom which is in contact with the exposed portion or the semiconductor pattern.
The first substrate and the second substrate include a first alignment layer ants a second alignment layer respectively. A part of the first alignment layer contacts contact the second alignment layer on a top surface of the patterned spacer. The patterned pacer includes a nontransparent layer on the organic layer. The nontransparent layer is wider than the exposed portion of the semiconductor pattern.
The liquid crystal display panel further including a data line formed on the first substrate and electrically coupled to one of the source and drain electrodes. The organic layer of the patterned spacer extends over the data line.
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patent: 3978580 (1976-09-01), Leupp et al.
patent: 4904056 (1990-02-01), Castleberry
patent: 5003356 (1991-03-01), Wakai et al.
patent: 6016181 (2000-01-01), Shimada
patent: 6266122 (2001-07-01), Kishimoto et al.
patent: 6429921 (2002-08-01), Chen et al.
patent: 6433852 (2002-08-01), Sonoda et al.
patent: 6573969 (2003-06-01), Watanabe et al.
patent: 4-68318 (1992-03-01), None
patent: 8-234212 (1996-09-01), None
patent: 9-22028 (1997-01-01), None
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