Liquid crystal cells – elements and systems – Particular structure – Having significant detail of cell structure only
Reexamination Certificate
1999-02-16
2001-05-08
Dudek, James A. (Department: 2871)
Liquid crystal cells, elements and systems
Particular structure
Having significant detail of cell structure only
Reexamination Certificate
active
06229586
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a reflection type liquid crystal display device, and in particular, to a reflection type liquid crystal display device that can be manufactured more easily than a conventional reflection type liquid crystal display device.
2. Description of the Related Art
In general, a liquid crystal display device is available in a transparent type device provided with backlighting and a reflection type device. A reflection type liquid crystal display device uses only external light such as sun light, illumination light and displays without backlighting, and is used mainly in a personal digital assistant required to be thin and lightweight.
FIG. 4
is a partial cross sectional view of one example of a conventional liquid crystal display device of reflection plate built-in type. The liquid crystal display device 1 of reflection plate built-in type generally comprises a pair of vertically-opposed glass substrates
2
and
3
, a sealing member
4
sandwiched by the pair of glass substrates
2
and
3
, and liquid crystal
5
sealed in a space surrounded by the sealing member
4
and the pair of glass substrates
2
and
3
. On the obverse surface of the upper glass substrate
2
, phase difference plates
6
,
7
and a polarizing plate
8
are laminated from the bottom side. On the reverse surface of the upper glass substrate
2
, a color filter
9
, a flattening film
17
, an electrode layer
10
made of ITO (indium tin oxide), an orientation film
31
are laminated. Further, on the obverse surface of the lower glass substrate
3
, an organic film
12
having depressions and projections on the surface thereof, a metallic reflection film
13
, a flattening film
14
, an electrode layer
15
made of ITO, and an orientation film
16
are laminated in order.
FIG. 5
is a partial enlarged cross sectional view of the portion near the end of the metallic reflection film
13
of the liquid crystal display device 1 of reflection plate built-in type. In the drawing, it should be appreciated that the various elements have not been drawn to exact scale and that some dimensions have been emphasized so that the invention disclosed can be clearly understood. The thickness of the lower glass substrate is about 0.7 mm, the maximum thickness of the organic film
12
is about 4 &mgr;m, the thickness of the metallic reflection film
13
is about 1000 Å, the maximum thickness of the flattening film
14
is about 5 &mgr;m, and the thickness of the electrode layer
15
is about 2000 Å. Further, the height of the depression and projection on the surface of the organic film
12
is about 1 to 2 &mgr;m.
When the depressions and projections are formed on the surface of the organic film
12
laminated on the lower glass substrate
3
by pressing a die to manufacture the reflection body, the shape of depression and projection tends to be disturbed at the end of the depressed and projected surface and an extremely pointed protrusion
12
a,
as shown in
FIG. 5
, might be formed. If the pointed protrusion
12
a
is formed, it is difficult to flatten the depressed and projected surface by the insulating flattening film
14
and hence the electrode layer
15
might be broken, or the metallic reflection film
13
and the electrode layer
15
might make a short circuit at the pointed protrusion
12
a.
In particular, in the electrode terminal forming region where the wiring lines of the electrode layer
15
are made dense because they are connected to a LSI or the like and where a wiring pattern is made complex because a circuit is formed, there is a strong possibility that the defective electrode layer
15
causes a serious problem in the liquid crystal display device 1 of reflection plate built-in type.
On the other hand, an alignment mark is formed on the glass substrate as a part used for aligning the glass substrates which are overlaid on each other or for printing the sealing member or the color filter on the substrate.
FIG. 6
is a cross sectional view of one example of the alignment mark formed on the glass substrate. As shown in
FIG. 6
, the alignment mark
15
a
on the lower glass substrate
3
is formed by patterning ITO, which is the same layer as the electrode layer
15
, on the peripheral portion of the lower glass substrate
3
. In this respect, if the depressions and projections are formed on the entire surface of the lower glass substrate
3
, it is difficult to recognize the alignment mark
15
a
and hence to manufacture the liquid crystal display device.
SUMMARY OF THE INVENTION
The present invention has been achieved in consideration of the above-described drawbacks of the conventional reflection type liquid crystal display device. An object of the present invention is to provide a reflection type liquid crystal display device that does not cause defects of a short circuit between a metallic reflection film and an electrode layer which are laminated on a substrate or a break in the electrode layer and that can be easily manufactured because various elements can be easily aligned.
A reflection type liquid crystal display device according to the present invention comprises a pair of substrates, a sealing member sandwiched by the pair of substrates, and liquid crystal sealed in a space surrounded by the sealing member and the pair of substrates, and is characterized in that many depressions and projections are formed on the surface of one substrate of the pair of substrates and that a metallic reflection film and a flattening film are laminated on the depressed and projected surface, and that many depressions and projections are formed on the surface of the substrate at least other than an electrode terminal forming region and that the surface of the substrate is made flat in the electrode terminal forming region.
In this specification, an electrode terminal forming region means a region where a terminal is formed to connect the wiring lines of an electrode layer to a LSI or the like or to form a drive circuit.
That is, in the electrode terminal forming region where the wiring lines of the electrode layer are made dense because they are connected to the LSI or the like or where a wiring pattern is made complex because the circuit is formed, the flat surface of the substrate can be made flat because many depressions and projections on the surface of the substrate are not formed there. This prevents defects such as a break in the electrode layer in the electrode terminal forming region and hence can improve the yield of the reflection type liquid crystal display device.
A reflection type liquid crystal display device according to the present invention is characterized in that many depressions and projections are formed on the surface of the substrate other than the electrode terminal forming region and an alignment mark forming region, and that the surface of the substrate is made flat in the electrode terminal forming region and the alignment mark forming region.
That is, when the glass substrates are overlaid on each other or the sealing member or the color film is printed, the alignment mark can be easily recognized because many depressions and projections are not formed on the surface of the substrate in the alignment mark forming region where the alignment mark is formed as a part for aligning the substrates, the sealing member, or the color film.
Further, the reflection type liquid crystal display device according to the present is characterized in that a boundary between a region where many depressions and projections are formed on the surface of the substrate and a flat region lies outside the sealing member, and that the end of the metallic reflection film lies inside the boundary and outside the sealing member.
That is, there is a possibility that a protrusion might be formed at the boundary of the region where many depressions and projections are formed on the surface of the substrate and a flat region, but since the boundary lies outside the sealing member, a gap between the substrates is not changed b
Date Takashi
Omote Kenji
Alp Electric Co., Ltd.
Brinks Hofer Gilson & Lione
Dudek James A.
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