Liquid crystal cells – elements and systems – Particular structure – Having significant detail of cell structure only
Reexamination Certificate
2001-04-17
2003-09-16
Niebling, John F. (Department: 2812)
Liquid crystal cells, elements and systems
Particular structure
Having significant detail of cell structure only
C349S106000, C349S113000
Reexamination Certificate
active
06621539
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a reflective type LCD, for example, a STN (super twisted nematic) type LCD, a TFT (thin film transistor) type LCD, and the like, and more specifically, to a reflective type LCD relating a construction of a reflective layer and a color layer thereof and to a method of manufacturing the same.
2. Description of the Related Art
A color filter with a reflective layer is used in a color reflective STN type LCD, and a reflection plate is used in a black and white STN type LCD, respectively.
FIG. 6
is a view explaining a manufacturing process of a conventional color filter with a reflective layer. First, as shown in
FIG. 6A
, after a hill and valley forming resist layer
52
is formed on a glass substrate
51
by coating photosensitive resin thereon and fine hills and valleys are formed on a surface of the resist layer
52
(FIG.
6
B), exposure L is executed to the resist layer
52
with a mask
53
placed thereon (FIG.
6
C), and a hard resin layer
54
is formed by developing and post baking the resist layer
52
(FIG.
6
D).
Next, as shown in
FIG. 6E
, a reflective layer
55
composed of aluminum or the like is formed on the hard resin layer
54
, a black mask resist
56
is coated on the reflective layer
55
(FIG.
6
F), thereafter a black mask
57
having a predetermined pattern is formed on the reflective layer
55
by exposing and developing the black mask resist
56
(FIG.
6
G). A blue filter
58
, a green filter
59
, and a red filter
60
are sequentially formed by the same manner, that is, by repeatedly coating, exposing and developing resists. (FIG.
6
H).
Thereafter, the thus obtained substrate is entirely covered with an overcoat layer
61
(FIG.
6
I), and then a protective layer
62
composed of SiO
2
and a transparent electrode
63
composed of ITO are sequentially formed on the overcoat layer
61
(FIG.
6
J), whereby the color filter with the reflective layer is constructed.
FIG. 7
is a partly enlarged sectional view of the color filter, wherein color filters such as the blue filter
58
, the green filter
59
, the red filter
60
and the like are formed with edges
64
thereof overlapping the black mask
57
in order to prevent leakage of light. The black mask
57
is formed to improve characteristics by improving contrast.
As shown in
FIG. 7
, in the conventional color filter with the reflective layer, since the edges
64
of the color filters overlap the black mask
57
, the edges
64
project upward and have a step &Dgr;t
1
of about 1 &mgr;m which approximately corresponds to a thickness of the black mask
57
.
While a surface of the color filter with the reflective layer is flattened by coating the overcoat layer
61
, a sufficient surface flattening effect cannot be obtained by the overcoat layer
61
because projections formed by the overlapped edges
64
have an area smaller than that of the portions of only the color filters. Thus, even if the overcoat layer
61
is formed, a step &Dgr;t
2
of about 0.5 to 1 &mgr;m remains on a surface of the overcoat layer
61
. Thus, there is a drawback that the step adversely affects display quality of a LCD.
Since very strict gap accuracy is required particularly to the STN type LCD, flatness having a higher degree of precision is indispensable to the STN type LCD.
SUMMARY OF THE INVENTION
Accordingly, an object of the present invention is to overcome the above drawbacks of the conventional art and to provide a reflective type LCD having high display quality and a method of manufacturing the same.
To achieve the above object, the present invention is characterized by including a substrate, for example, a glass substrate or the like, one color layer, for example, a black mask or the like formed on an approximately overall surface of a display region of the substrate, and a reflective layer composed of, for example, aluminum or the like and covering the other portion of the color layer excluding a desired pattern portion thereof, wherein the pattern of the one color layer is exposed through the reflective layer.
The above invention is characterized in that the one color layer is a black and white type black mask.
The above invention is characterized in that the one color layer is a color type black mask, a color filter having a blue filter, a green filter, and a red filter is disposed on the reflective layer, and edges of the color filter partly overlap the black mask.
The above invention is characterized in that fine hills and valleys are formed on a surface of the one color layer.
The above invention is characterized in that the LCD is a STN (super twisted nematic) type LCD.
Further, the present invention is characterized by including the steps of forming one color layer, for example, a black mask or the like on an approximately overall surface of a display region of a substrate, for example, a glass substrate or the like, forming a reflective layer composed of, for example, aluminum or the like on an approximately overall surface of the one color layer and partly removing the reflective layer and exposing a pattern of the one color layer through the remaining reflective layer.
The above invention is characterized in that the one color layer is a white and black type black mask.
The above invention is characterized in that the one color layer is a black mask and the invention includes the step of patterning a color filter having a blue filter, a green filter, and a red filter on the remaining reflective layer and partly overlapping edges of the color filter on the black mask.
The above invention is characterized by including the step of forming fine hills and valleys on a surface of the one color layer.
The above invention is characterized in that the LCD is a STN (super twisted nematic type) LCD.
REFERENCES:
patent: 5220444 (1993-06-01), Mitsui et al.
patent: 5990992 (1999-11-01), Hamanaka et al.
patent: 6476890 (2002-11-01), Funahata et al.
Alps Electric Co. ,Ltd.
Beyer Weaver & Thomas LLP
Simkovic Viktor
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