Liquid crystal cells – elements and systems – Particular structure – Having significant detail of cell structure only
Reexamination Certificate
2000-02-25
2002-08-06
Sikes, William L. (Department: 2871)
Liquid crystal cells, elements and systems
Particular structure
Having significant detail of cell structure only
C349S111000, C349S122000, C349S138000, C349S106000
Reexamination Certificate
active
06429917
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to a color liquid-crystal panel and a manufacturing process therefor. In particular, it relates to a color liquid-crystal panel comprising a switching element such as a thin-film transistor (TFT), a color filter and a black matrix on a single substrate.
2. Description of the Prior Art
A color liquid-crystal panel is conventionally constituted by first substrate
1
having a switching element such as a TFT comprising a gate electrode
2
, a gate insulating film
3
, a semiconductor layer
4
and source-drain electrodes
5
and
6
, interconnection layers to the individual electrodes (not shown), all of which are covered by an interlayer film
7
, pixel electrodes
11
to individual pixels, which are covered by a passivation film
12
, an oriented film
18
a
, and a terminal
13
for interconnection with an external circuit; and a second substrate
16
comprising a black matrix
8
, color filter layers
10
R,
10
G and
10
B for individual colors R, G and B, respectively, a transparent common electrode
17
such as an ITO, and an oriented film
18
b
, where these substrates are put together via an intervening spacer
14
for ensuring a given gap between them and a sealer
15
surrounding their peripheries in a manner that their device-forming surfaces face, as shown in FIG.
11
. Then, the sealer is burned, a gap between both substrates is determined and then a liquid-crystal material
19
is poured into the panel.
Liquid crystal may be injected by, e.g., a two-hole method where two holes are formed in selected places in the panel and liquid crystal is injected from one hole while the panel is vacuumed from the other hole to facilitate feeding the liquid crystal, or a vacuum-injection method where an empty cell having an inlet and liquid crystal are vacuumed to 1×10
−2
to 1×10
−4
Torr to deposit the liquid crystal around the inlet and then the vacuum of the system is gradually broken to the atmospheric pressure so that a pressure difference between the inside and the outside of the liquid-crystal cell induces transfer of the liquid crystal into the inside of the cell. The latter method has been predominantly employed.
After injecting liquid crystal, the inlet is sealed and then polarizing plates
20
a
and
20
b
are attached to the outer faces of the substrates to provide a liquid-crystal panel.
To improve definition of a liquid-crystal panel, it is necessary to provide a higher pixel density. A conventional liquid-crystal panel where a color filter and a black matrix are disposed on a substrate facing to an active-matrix substrate must be manufactured with a given margin for an alignment error which may occur during an assembling process. It has been, therefore, difficult to ensure the maximum area of the pixel opening (opening ratio).
Thus, there has been proposed a method where a color filter and a black matrix are formed on an active-matrix substrate comprising a switching element such as a TFT (CF-on-TFT; hereinafter, referred to as “COT”).
Due to forming a color filter and a black matrix on a COT substrate, it is not necessary to consider an assembling margin, leading to a more simplified manufacturing process and increase in a pixel opening ratio.
However, forming a color filter or black matrix directly on a TFT or an interconnection may cause malfunctioning of the switching element because elements or ions in the color filter or black matrix enter into the main component of the switching element. Thus, JP-A 10-39292 has proposed that a protective film, i.e., a passivation film, is formed between a switching element and a color filter.
SUMMARY OF THE INVENTION
An object of this invention is to disclose a specific structure for such a COT type of liquid-crystal panel. The above application (JP-A 10-39292 has not described an edge structure for a liquid-crystal panel.
This invention provides a color liquid-crystal panel comprising the first substrate having pixel electrodes on which are formed a thin-film transistor as a switching element for each pixel, which is covered by a passivation film, and a color filter layer and a black matrix on the passivation film, which are covered by an overcoat layer, and where the first substrate and the second substrate having a transparent common electrode facing the first substrate are put together via a sealer, forming an inner space which is filled with a liquid-crystal material, wherein a frame-shaped black matrix covers the periphery of the first substrate.
According to this invention, a liquid-crystal panel suitable for a COT configuration can be provided.
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patent: 5446562 (1995-08-01), Sato
patent: 5739880 (1998-04-01), Suzuki et al.
patent: 5818550 (1998-10-01), Kadota et al.
patent: 5933208 (1999-08-01), Kim
patent: 6002462 (1999-12-01), Sato et al.
patent: 6038006 (2000-03-01), Sasaki et al.
patent: 6118505 (2000-09-01), Nagata et al.
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patent: 4-342229 (1992-11-01), None
patent: 5-88189 (1993-04-01), None
patent: 09-146084 (1997-06-01), None
patent: 09-160015 (1997-06-01), None
patent: 10-39292 (1998-02-01), None
patent: 10-325951 (1998-12-01), None
patent: 11-133404 (1999-05-01), None
patent: 11-212045 (1999-08-01), None
patent: 11-295744 (1999-10-01), None
Ihara Hirofumi
Kikkawa Hironori
Nakata Shinichi
Okamoto Mamoru
Sakamoto Michiaki
Chowdhury Tarifur R.
Hayes & Soloway P.C.
NEC Corporation
Sikes William L.
LandOfFree
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