Liquid crystal cells – elements and systems – Particular structure – Having significant detail of cell structure only
Reexamination Certificate
1997-05-13
2002-05-14
Sikes, William L. (Department: 2871)
Liquid crystal cells, elements and systems
Particular structure
Having significant detail of cell structure only
C349S153000
Reexamination Certificate
active
06388728
ABSTRACT:
FIELD OF THE INVENTION AND RELATED ART
The present invention relates to an electrode plate including metal electrodes with gaps therebetween filled with a resin, a process for producing the electrode plate, a liquid crystal device including the electrode plate, and a process for producing the liquid crystal device.
Electrode plates conventionally used in liquid crystal devices of, e.g., a twisted nematic (TN)-type and a super twisted nematic (STN)-type generally comprise a glass substrate and transparent electrodes of ITO (indium-tin-oxide), etc., formed thereon. However, such transparent electrodes have a fairly high resistivity so that they have caused a problem of voltage waveform deformation due to electrical signal delay along with increases in size and resolution of the display area. This problem is particularly noticeable in the case of a liquid crystal device using a ferroelectric liquid crystal due to a smaller cell gap.
In order to solve the problem, it may be possible to increase the thickness of the transparent electrodes, but the formation of such thick transparent electrodes requires increased time and cost and results in a lower transparency of the electrodes.
In order to solve the above-mentioned problems, it has been practiced to form a metal electrode along a transparent electrode of a small thickness (as disclosed in Japanese Laid-Open Patent Application (JP-A) 2-63019). According to the practice, an electrode plate having metal electrodes thereon embedded with a transparent insulating material is provided, and transparent electrodes of ITO film, etc., are formed thereon so as to be electrically connected with the corresponding metal electrodes, respectively, via through-holes in the insulating material.
In producing an electrode plate having a structure as described above, it has been also proposed to use a transparent resin as the insulating material filling the gaps between the metal electrodes (e.g., JP-A 6-347810 and JP-A 8-304842) as illustrated in
FIGS. 23
to
25
.
According to the proposed process, as shown in
FIG. 23A
, on a smooth or smoothening mold substrate (hereinafter called “smooth plate”)
100
, a prescribed amount of a liquid resin of ultraviolet (UV)-curable resin
101
is placed dropwise by using a dispenser (not shown). Then, as shown in
FIGS. 23B
and
23
C, a glass substrate
104
already provided with a pattern of ca. 1 &mgr;m-thick metal electrodes
103
is placed thereon so that the surface thereof provided with the metal electrodes
103
contacts the liquid resin
101
.
Further, as shown in
FIGS. 24A and 24B
, the smooth plate
100
and the substrate
104
are pressed to each other to ensure an intimate contact over the entire area by pressing with a press
105
. In this step, in order to ensure a good contact and electrical conductance between the metal electrodes
103
and corresponding transparent electrodes formed in a later step, the smooth plate
100
and the substrate
104
are caused to come in contact with each other strongly and uniformly over the entire area so as to remove the UV-curable resin
101
from the metal electrode surface completely or to the extent that a very small amount of the resin
101
remains on a part of the metal electrode surface.
Thereafter, the substrate
104
in contact with the smooth plate
100
is taken out from the press
105
and is irradiated with UV rays
106
from the substrate side by using a mask (not shown) disposed in a peripheral region of the substrate
104
to cure the UV-curable resin
101
, as shown in FIG.
25
A. Then, the smooth plate
100
.is removed from the substrate
104
by using a peeling unit (not shown), followed by ultrasonic cleaning in, e.g., isopropyl alcohol (IPA) to remove the uncured resin, thus obtaining an electrode plate
107
having thereon a plurality of metal electrodes
103
and a UV-cured resin
101
filling the gaps between the metal electrodes
103
, as shown in
FIGS. 25B and 25C
.
In the above-described production process of the electrode plate, however, as shown in
FIG. 24B
, a part
101
a
of the UV-curable resin
101
flows out or is squeezed out from the side (edge) portions between the smooth plate
100
and the glass substrate
104
under pressure in the pressing (or resin-filling) step. In such a state, even when the smooth plate
100
and the glass substrate
104
are further pressed against each other by further increasing an applied pressure by means of the press
105
, the UV-curable resin
101
disposed therebetween is not extended or expanded any longer. As a result, a part of the gaps between the metal electrodes
103
is not filled or is partially filled with the UV-curable resin
101
to result in an uneven surface portion, thus being liable to cause adhesion (or contact) failure between the metal electrodes and associated transparent electrodes, respectively, in a later step.
Further, the flowing-out part
101
a
of the UV-curable resin
101
as described above is attached to and contaminates the press
105
, thus leading to dirt when such a press
105
is repetitively used. Consequently, a production yield of the electrode plate is liable to be lowered.
SUMMARY OF THE INVENTION
In view of the above-mentioned problems, a principal object of the present invention is to provide an electrode plate improved in uniformity and flatness (or planarity) of a resin filling gaps between metal electrodes formed on a substrate and capable of preventing contamination due to flowing-out of the resin, thus enhancing a product yield, and a liquid crystal device including such an electrode plate.
Another object of the present invention is to provide processes for producing an electrode plate and a liquid crystal device as described above.
According to the present invention, there is provided an electrode plate, comprising: a substrate, a plurality of metal electrodes formed with gaps therebetween in a prescribed pattern on the substrate, and a resin filling the gaps; wherein
the substrate is provided with an elongated projection disposed in a peripheral region thereof.
According to another aspect of the present invention, there is provided a process for producing an electrode plate comprising the steps of:
forming on a substrate a plurality of metal electrodes with gaps therebetween in a prescribed pattern,
forming an elongated projection in a peripheral region of the substrate,
placing a resin between the substrate and a mold substrate, and
filling the gaps with the resin by pressing within a region inside said elongated projection.
According to another aspect of the present invention, there is also provided a process for producing an electrode plate comprising the steps of:
forming on a substrate a plurality of metal electrodes with gaps therebetween in a prescribed pattern,
forming an elongated projection in a peripheral region of a mold substrate,
placing a resin between the substrate and the mold substrate, and
filling the gaps with the resin by pressing within a region inside said elongated projection.
According to a further aspect of the present invention, there is provided a liquid crystal device, comprising: a pair of oppositely disposed plates, and a liquid crystal disposed between the plates; at least one of the plates having an electrode plates comprising:
a substrate, a plurality of metal electrodes formed with gaps therebetween in a prescribed pattern on the substrate,:and a resin filling the gaps, and a plurality of transparent electrodes each electrically connected with an associated metal electrode; wherein
the substrate is provided with an elongated projection disposed in a peripheral region thereof.
According to a still further aspect of the present invention, there is provided a process for producing a liquid crystal device in which a liquid crystal is disposed between a pair of oppositely disposed plates including at least one electrode plate comprising: a substrate, a plurality of metal electrodes formed with gaps therebetween on the substrate, a resin filling the gaps, and a plurality of transparent electrodes each electri
Kamio Masaru
Matsuo Yuji
Tokunaga Hiroyuki
Tomono Haruo
Nguyen Dung
Sikes William L.
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