Plastic color filter manufacturing method and color filter manufactured in the manufacturing method

An insulating layer is formed on a plurality of electrodes formed on a plastic film substrate, the insulating layer having a plurality of electrode connecting holes formed therein. Electrodes of the plurality of electrodes are selectively connected to an external circuit via respective ones of the plurality of connecting holes. Conductive color filter layers are formed on the thus-connected electrodes by an electrochemical method. A value obtained as a result of subtracting a width of each one of the plurality of electrode connecting holes from a width of a respective one of the plurality of electrodes is large so that a position of the electrode connecting hole is maintained to correspond to a position of the electrode even when the plastic film substrate expands or contracts maximally.

BACKGROUND OF THE INVENTION 
1. Field of the Invention 
The present invention relates to a color liquid-crystal display device, 
and, in particular, to a liquid-crystal display device which is superior 
as a portable device and uses a plastic-film substrate. 
2. Description of the Related Art 
Liquid-crystal display devices have been used in various fields. As an 
information display device, a liquid-crystal display device is a match for 
a CRT. In particular, in a portable apparatus, it is demanded that a size 
of the apparatus be small, a weight of the apparatus be light, and power 
consumption of the apparatus be low. Therefore, a liquid-crystal display 
device is used in such a portable apparatus in many cases. In almost all 
cases, a liquid-crystal display device uses a glass as a substrate. 
However, in a portable apparatus such as a portable telephone, an 
electronic pocket book or the like, a liquid-crystal display device using 
a plastic film as a substrate is used. A plastic film has a thickness on 
the order of 0.1 through 0.3 mm, and the weight thereof is light. 
Therefore, a plastic film is suitable for being used in a portable 
apparatus. However, performing fine patterning on a plastic-film substrate 
is difficult. Further, the dimensions of a plastic-film substrate change 
due to environmental changes in temperature, humidity and so forth. 
Therefore, it is difficult to put a color filter using a plastic-film 
substrate into practice. As a result, in almost all cases, a plastic-film 
substrate is used in a monochrome display device. A color displaying 
method which does not use a color filter using a plastic-film substrate 
has been proposed. However, in this method, the number of colors which can 
be displayed is limited, and displayed colors are not clear. Further, in 
this method, it is necessary to strictly control a distance (cell gap) 
between two substrates. Because control of the distance between two 
substrates is difficult in a plastic-film liquid-crystal display device, 
this method has yet to be put into practice. 
As methods for manufacturing a color filter for a liquid crystal, various 
methods such as a dye dissolution method, a pigment dispersed method, an 
electro-deposition method, a micelle-disruption method, a printing method 
and so forth have been proposed. (With regard to the micelle-disruption 
method, see `Formation of Organic Thin Films by Electrolysis of 
Surfactants with the Ferrocenyl Moiety`, Tetsuo Saji, Katsuyosi Hoshino, 
Yoshiyuki Ishii, and Masayuki Goto, J. Am. Chem. Soc. 1991, 113, 450-456.) 
In each of the dye dissolution method, pigment dispersed method, printing 
method and so forth, in forming patterns of red (R), green (G), blue (B) 
and black (BK), it is necessary to accurately positioning each pattern 
with respect to the other patterns. For example, first, a black pattern is 
formed, and, then, red, green and blue patterns are accurately positioned 
with respect to the black pattern and are thus formed. Further, 
positioning between the color filter patterns and liquid-crystal driving 
electrodes is also necessary. An accuracy in positioning depends on 
material, size, and manufacturing apparatus for a substrate to be used. 
When a glass substrate is used, it is possible to perform positioning on 
the order of microns. In comparison to the glass substrate, a plastic 
substrate changes in dimensions greatly. Not only due to thermal 
hysteresis but also due to temperature and humidity changes, a plastic 
substrate changes in dimensions by .+-.0.1%. Therefore, it is very 
difficult to perform accurate positioning of color filter patterns. In 
order to put forming of color filter patterns on a plastic-film substrate 
into practice, a manufacturing process, which does not need accurate 
positioning of color filter patterns, or, in which the number of steps 
which needs accurate positioning is reduced to the utmost, is demanded. 
In each of the electro-deposition method and micelle-disruption method of 
the above-mentioned methods for manufacturing color filters, color filter 
layers are formed on transparent conductive film patterns 
electrochemically. Therefore, deviation in positions of the respective 
colors, R, G, B, with respect to each other does not occur. 
Japanese Laid-Open Patent Application No. 6-34809 discloses using 
electrodes for driving liquid crystal also as electrodes by which color 
filter layers are formed, as a result of making the color filter layers of 
conductive material or mixing conductive material in the color filter 
layers. 
When the color filter layers are conductive, when a plurality of colors 
(for example, three colors, R, G, B) of color filter layers are formed, it 
is necessary to selectively connect the electrodes to an external circuit 
for each color. Generally speaking, the pitch of the electrodes is equal 
to or less than 100 .mu.m. It is difficult to directly probe each 
electrode so as to connect the electrode to an external circuit. 
Therefore, in the art disclosed in Japanese Laid-Open Patent Application 
No. 3-102302, as shown in FIG. 1, electrode connecting holes 2 are formed 
in a photosensitive resin 3 so that electrodes 1 for the respective colors 
R, G, B on a substrate 4 can be selectively connected to an external 
circuit. Then, as shown in FIG. 2, the electrodes 1 are selectively 
connected to the external circuit 7 through conductive silver paste 6. 
Then, a color filter forming area 5 is immersed in electrolytic liquid, 
and a voltage is applied to the electrodes selectively connected to the 
external circuit 7. As a result, color filter layers 8 are formed on the 
electrodes 1, respectively. However, when attempting to form conductive 
color filter layers on a plastic film in this method, problems such as 
shifting of the electrode connecting holes 2 from the electrodes 1, poor 
electrical connection between the electrodes 1 and the silver paste 6, and 
so forth, due to change in dimensions of the substrate 4, occurred. As a 
result, good conductive color filter layers could not be formed. 
Further, Japanese Laid-Open Patent Application Nos. 2-175897 and 3-4202 
disclose methods in which electrode connecting holes 2 are not used, and, 
electrodes after being colored are cut by etching. However, in either 
method, manufacturing steps are complicated, and it is difficult to apply 
the method to a plastic film substrate. 
SUMMARY OF THE INVENTION 
An object of the present invention is to solve the above-described problems 
by providing a method for forming conductive color filters by an 
electrochemical method on a plastic film substrate, this film substrate, 
and a plastic color liquid-crystal display device using this substrate. 
A plastic color filter manufacturing method, according to the present 
invention, comprises the steps of: 
forming an insulating layer on a plurality of electrodes formed on a 
plastic film substrate, the insulating layer having a plurality of 
electrode connecting holes formed therein; 
selectively connecting electrodes of the plurality of electrodes to an 
external circuit via respective ones of the plurality of connecting holes, 
in turn; and 
forming conductive color filter layers on the thus-connected electrodes in 
by electrochemical method, 
wherein a value obtained as a result of subtracting a width of each one of 
the plurality of electrode connecting holes from a width of a respective 
one of the plurality of electrodes is large enough so that a position of 
the electrode connecting hole is prevented from deviating from a position 
of the electrode even when the plastic film substrate expands or contracts 
maximally. 
The width of each one of said plurality of electrodes at a position where a 
respective one of said plurality of electrode connecting holes is placed 
may be greater than a width of the electrode at a position at which the 
conductive color filter layer is formed on the electrode. 
Thus, according to the present invention, as a result of the width of each 
electrode being widened at the position at which a respective one of the 
electrode connecting holes is positioned, an allowable range in alignment 
of the electrode connecting hole with the electrode is widened. Thereby, 
it is not likely to occur that the position of the electrode connecting 
hole deviates from the position of the electrode, even when the plastic 
film substrate expands or contracts maximally. That is, as a result of the 
width of each electrode being widened at the position at which a 
respective one of the electrode connecting holes is positioned, the 
position of the electrode connecting hole does not deviate from the 
position of the electrode, even when the plastic film substrate which 
expands or contracts significantly is used. 
The electrical connection between selected ones of the plurality of 
electrodes and the external circuit may be performed through conductive 
resin which can change in shape in response to a change in shape of the 
plastic film substrate. 
The step of electrically connecting the selected ones of the plurality of 
electrodes with the external circuit may comprise the steps of: 
scattering conductive particles in at least respective ones of the 
plurality of electrode connecting holes; and 
performing the electrical connection of the selected ones of the plurality 
of electrodes with the external circuit through the conductive particles 
and a conductive material. 
A diameter of each of the conductive particles may be larger than a 
thickness of the insulating layer, the electrical connection being made 
between selected ones of the plurality of electrodes and the external 
circuit as a result of the conductive material being pressed on the 
insulating layer. 
The conductive particles may be soft. 
The step of electrically connecting the selected ones of the plurality of 
electrodes with the external circuit may comprise the steps of: 
depositing a layer in each of at least respective ones of the plurality of 
electrode connecting holes; and 
electrically connecting the selected ones of the plurality of electrodes 
with the external circuit through the thus-deposited layers and a 
conductive material. 
A thickness of each of the deposited layers may be larger than a thickness 
of the insulating layer, the electrical connection being made between the 
selected ones of the plurality of electrodes and the external circuit as a 
result of the conductive material being pressed on the insulating layer. 
The deposited layers may comprise layers formed through plating. 
The conductive material may comprise an adhesive tape. 
The step of electrically connecting the selected ones of the plurality of 
electrodes with the external circuit may be performed using a conductive 
material which has a surface having irregularities of a height on the 
order of a thickness of the insulating layer. 
The irregularities of the surface of the conductive material may comprise 
soft conductive resin. 
The conductive material may comprise an adhesive tape. 
A plastic color filter according to the present invention is made in any of 
the above-described methods. 
As a result, good electrical connection is made between the selected ones 
of the plurality of electrodes and the external circuit. Thereby, the 
plastic color filter having the conductive color filter layers, without 
any defects and any color nonuniformity, on the electrodes, respectively, 
can be formed. 
A color liquid-crystal display device according to the present invention 
comprises: 
two substrates; and 
an electrooptic-material layer, a light transmitting condition thereof 
being electrically controlled, the electrooptic material layer being 
sandwiched by the two substrates, 
wherein, as a result of an electric field being applied to the 
electrooptic-material layer by a plurality of electrodes, on which 
conductive color filter layers are formed, the electrooptic-material layer 
displays information, and 
wherein at least one of the two substrate comprises any of the 
above-described plastic color filters. 
Thereby, it is possible to provide the color liquid-crystal display device 
which can perform improved color display. 
Other objects and further features of the present invention will become 
more apparent from the following detailed descriptions when read in 
conjunction with the accompanying drawings.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
A method for manufacturing a plastic color filter according to the present 
invention and a structure of the plastic color filter will now be 
described. 
As a method for selectively connecting arbitrary ones of a plurality of 
electrodes formed on a plastic film substrate to an external circuit, an 
insulating layer having electrode connecting holes formed therein is 
formed on the electrodes. As such an insulating layer, not only an 
inorganic film such as that of SiOx, alumina or the like, but also an 
organic film such as that of epoxy resin, acrylic resin, polyimide resin 
or the like is used. However, because the plastic film substrate is used, 
it is preferable to use the organic film for which a processing 
temperature is relatively low. As a method for forming the electrode 
connecting holes (which may also be referred to as contact holes) in the 
insulating layer, an ordinary photolithography process is used. It is 
possible to simplify the process as a result of using photosensitive resin 
as the insulating layer. The thickness of the insulating layer may be on 
the order of 0.1 through 10 .mu.m. However, in order to provide positive 
insulation, it is preferable to use the insulating layer having the 
thickness equal to or more than 0.3 .mu.m. 
As mentioned above, the dimensions of the plastic film substrate change 
greatly. Therefore, it is not possible to perform accurate alignment. As a 
result, as shown in FIG. 3, it is necessary to sufficiently reduce the 
width of each contact hole 2 in comparison to the width of a respective 
one of the electrodes 1. For example, when the contact hole 2 having a 
width w2 of 20 .mu.m is formed on the electrode 1 having a width w1 of 100 
.mu.m, 80 .mu.m, which is a difference between the width w1 of the 
electrode 1 and the width w2 of the contact hole 2, is an alignment 
margin. However, when the width w2 of the contact hole 2 is excessively 
reduced in order to obtain a larger alignment margin, it is difficult to 
achieve positive electrical connection with the electrode 1 via the 
contact hole 2. Therefore, it is preferable to have the width w2 of the 
contact hole 2 equal to or more than 5 .mu.m. In order to achieve more 
positive electrical connection, it is further preferable to have the width 
w2 of the contact hole 2 equal to or more than 20 .mu.m. Therefore, 
instead of reducing the width w2 of the contact hole 2, the width w1 of 
the electrode 1 at the position at which the contact hole 2 is formed is 
widened, as shown in FIG. 4. Thereby, the alignment margin is increased. 
Thus, even when using the plastic film substrate which significantly 
changes in dimensions, the contact holes 2 are formed through the 
photolithography process and good electrical connection with the 
electrodes 1 via the contact holes 2 can be obtained. 
In order to electrically connect the electrodes on the substrate with an 
external circuit via the contact holes, respectively, a method in which 
metallic-material film is formed on the insulating layer through an 
ordinary vapor deposition method or the like can be used. On the other 
hand, a method in which a conductive resin such as silver paste or the 
like is used can be easily performed. However, the plastic film substrate 
changes in dimensions due to thermal hysteresis, and changes in 
temperature and humidity, as mentioned above. Therefore, it is likely that 
the conductive resin peels off and poor electrical connection with the 
electrodes via the contact holes, respectively, occurs. Such phenomenon is 
more likely to occur when the size of each of the contact holes is small. 
When various trials were made in order to eliminate occurrence of poor 
electrical connection, it was found that the following methods are 
effective: a method in which conductive resin which can change in size in 
response to a change in shape of the substrate, for example, a resin, such 
as polyester, polyurethane, silicon or the like, which has a small elastic 
modulus, is used for electrically connecting the electrodes with an 
external circuit via the contact holes, respectively; a method in which, 
as shown in FIG. 5, after conductive particles 9, such as those made of 
nickel, gold or the like, or conductive resin particles 9, each of which 
has a metal film coated thereon, are scattered in each contact hole 2, a 
conductive layer 10 such as conductive paste, a metal plate, a metal tape 
or the like is pressed on the insulating layer 3; a method in which, as 
shown in FIG. 6, a conductive layer 11 having a surface having 
irregularities is pressed on the insulating layer 3; and a method in 
which, as shown in FIG. 7, after a conductive layer 12 is deposited 
through plating or the like in each contact hole 2, a conductive layer 10 
such as conductive paste, a metal plate, a metal tape or the like is 
pressed on the insulating layer 3. Further, as a result of using the 
conductive particles 9, each having the diameter larger than the thickness 
of the insulating layer 3, to be scattered in each contact hole 2, and/or 
using the soft conductive particles 9 to be scattered in each contact hole 
2, it is possible to obtain more positive electrical connection with the 
electrodes 1 via the contact holes 2, respectively. Similarly, as a result 
of using the conductive layer 11 having the surface having irregularities 
shown in FIG. 6, the irregularity of the surface being made of soft 
conductive material such as conductive silicon resin, it is possible to 
obtain more positive electrical connection with the electrodes 1 via the 
contact holes 2, respectively. Further, as a result of using an adhesive 
resin tape as the conductive layer 10 or 11, shown in FIGS. 5, 6 or 7, the 
work efficiency in the filter manufacturing process can be improved. 
Embodiments of the present invention will now be described. 
A first embodiment of the present invention will now be described. 
A transparent conductive layer on a plastic film in a transparent 
conductive film FST-5340 (substrate, made by Sumitomo Bakelite Co., Ltd. 
of Japan) having the size of 150 mm by 150 mm and the thickness of 0.15 mm 
is processed through an ordinary photolithography method so that 960 
stripe-shaped electrodes 1 are formed, the pitch thereof being 110 .mu.m, 
and the width of each electrode being 90 .mu.m. Then, after posi-type 
photoresist is coated on the entire surface of the substrate so that a 
layer having the thickness of approximately 2 .mu.m is formed thereon, a 
photo-mask is used, exposure and development are performed, and thus, the 
insulating layer 3, having the contact holes 2 each having the width of 20 
.mu.m and the length of 100 .mu.m formed therein, is formed, as shown in 
FIG. 3. Thus, a plastic film substrate in the first embodiment is 
produced. In this case, the contact holes 2 each having the width of 20 
.mu.m are aligned with the electrodes 1 each having the width 90 .mu.m, 
respectively. Thus, the alignment margin is 70 .mu.m. Therefore, when the 
change in dimensions of the substrate is within the range of .+-.0.02%, it 
is possible to align each contact hole 2 with a respective one of the 
electrodes 1. In this embodiment, as a result of managing the time from 
the pre-baking finish time until the exposure, the dimensions of the 
substrate are controlled to be within .+-.0.02%. 
A second embodiment of the present invention will now be described. 
Similar to the first embodiment, a transparent conductive layer on a 
plastic film in a transparent conductive film FST-5340 (substrate, made by 
Sumitomo Bakelite Co., Ltd. of Japan) having the size of 150 mm by 150 mm 
and the thickness of 0.15 mm is processed through an ordinary 
photolithography method so that the 960 stripe-shaped electrodes 1 are 
formed, the pitch thereof being 110 .mu.m, and the width of each electrode 
being 90 .mu.m. At a position where the contact holes 2 are formed, the 
electrodes 1 have patterns such as those shown in FIG. 4. Thus, at the 
position, the width w1 of each electrode 1 is widened to 250 .mu.m. In 
this pattern, the width w1' of the electrodes 1 at which the width of the 
electrodes 1 is narrowest is 20 .mu.m. Then, after posi-type photoresist 
is coated on the entire surface of the substrate so that a layer having 
the thickness of approximately 2 .mu.m is formed, a photo-mask is used, 
exposure and development are performed, and thus, similar to the first 
embodiment, the insulating layer 3, having the contact holes 2 each having 
the width of 20 .mu.m and the length of 100 .mu.m formed therein, is 
formed. Thus, a plastic film substrate in the second embodiment is 
produced. In this case, the contact holes 2 each having the width of 20 
.mu.m are aligned with the electrodes 1 each having the width 250 .mu.m at 
the position where the contact holes 2 are formed, respectively. Thus, the 
alignment margin is 230 .mu.m. Therefore, when the change in dimensions of 
the substrate is within the range of .+-.0.08% (larger than .+-.0.02% in 
the first embodiment), it is possible to align each contact hole 2 with a 
respective one of the electrodes 1. 
A third embodiment of the present invention will now be described. 
The plastic film substrate in the first embodiment is annealed for one hour 
at 180.degree. C. so that a solvent resistance of the photoresist is 
increased. Then, conductive paste, which is obtained as a result of filler 
(minute powder) of silver being dispersed in polyurethane resin, is coated 
by a dispenser at a position 13 shown in FIG. 8, and is dried at 
120.degree. C. The conductive paste after being dried has a width of 0.5 
mm and a thickness of 0.5 mm. The substrate on which the conductive paste 
has been thus formed is immersed in micelle solution consisting of red 
hydrophobic pigment, conductive particles, surfactants and a supporting 
electrolyte. Then, a voltage is applied to the conductive paste, and 
thereby, red conductive color filter layers are formed on the electrodes 
1, respectively, which are connected with the conductive paste and are 
thus selected. Then, the substrate is washed by demineralized water, and 
then, is dried at 120.degree. C. Similarly, after the conductive paste is 
coated at a position 13' shown in FIG. 8, by using a micelle solution in 
which green hydrophobic pigment instead of the red hydrophobic pigment is 
dispersed, green conductive color filter layers are formed. Similarly, 
after the conductive paste is coated at a position 13" shown in FIG. 8, by 
using a micelle solution in which blue hydrophobic pigment instead of the 
red hydrophobic pigment is dispersed, blue conductive color filter layers 
are formed. Thus, a plastic color filter including the red, green and blue 
color filter layers is formed. (The contact holes 2 formed on the 
electrodes 1 on which the green color filter layers are formed are apart 
from the contact holes 2 formed on the electrodes 1 on which the red color 
filter layers are formed sufficiently so that the conductive paste coated 
at the position 13' does not come into contact with the conductive paste 
coated at the position 13. Similarly, the contact holes 2 formed on the 
electrodes 1 on which the blue color filter layers are formed are apart 
from the contact holes 2 formed on the electrodes 1 on which the green 
color filter layers are formed sufficiently so that the conductive paste 
coated at the position 13" does not come into contact with the conductive 
paste coated at the position 13'.) Thus, a plastic color filter 
(substrate) is produced. As a result of the soft polyurethane resin being 
used as the conductive paste, electrical connection between the conductive 
paste and the electrodes 1 can be positively performed. As a result, a 
color filter free from a coloring defect can be produced. 
A fourth embodiment of the present invention will now be described. 
The plastic film substrate in the first embodiment is annealed for one hour 
at 180.degree. C. so that a solvent resistance of the photoresist is 
increased. Then, conductive paste, which is obtained as a result of filler 
(minute powder) of silver being dispersed in acrylic resin, is coated by a 
dispenser, after nickel particles each having the diameter of 1 .mu.m are 
scattered in each contact hole, and is dried at 100.degree. C. Then, in a 
method similar to the method described in the description of the third 
embodiment, the conductive color filter layers are formed. Thus, the 
plastic color filter (substrate) is produced. In comparison to the 
polyurethane resin or silicon resin, the acrylic resin has a large elastic 
modulus. As a result, poor electrical connection with the electrodes 1 is 
likely to occur. However, as a result of the conductive particles (nickel 
particles) being scattered in each contact hole before the conductive 
paste of the acrylic resin is coated, electrical connection between the 
conductive paste and the electrodes 1 can be positively performed through 
the conductive particles. As a result, the color filter free from a 
coloring defect can be produced. 
A fifth embodiment of the present invention will now be described. 
After nickel particles each having a diameter of 3 .mu.m are scattered in 
each contact hole 2 of the plastic film substrate in the first embodiment, 
an aluminum plate having a width of 2 mm, a thickness of 2 mm and a length 
of 200 mm is pressed on the insulating layer 3. Thus, the aluminum plate 
10 and the electrodes 1 are electrically connected through the nickel 
particles 9 as shown in FIG. 5. Then, in a method similar to the method 
described in the description of the third embodiment, the conductive color 
filter layers are formed on the electrodes 1, respectively. In the fifth 
embodiment, the aluminum plate is pressed at the position 13 shown in FIG. 
8 when the red color filter layers are formed, is pressed at the position 
13' when the green color filter layers are formed, and is pressed at the 
position 13" when the blue color filter layers are formed. (The contact 
holes 2 formed on the electrodes 1 on which the green color filter layers 
are formed are apart from the contact holes 2 formed on the electrodes 1 
on which the red color filter layers are formed sufficiently, and the 
contact holes 2 formed on the electrodes 1 on which the blue color filter 
layers are formed are apart from the contact holes 2 formed on the 
electrodes 1 on which the green color filter layers are formed 
sufficiently so that the aluminum plate pressed at the position 13 covers 
neither the contact holes 2 which should be pressed by the aluminum plate 
when the aluminum plate is pressed at the position 13' nor the contact 
holes 2 which should be pressed by the aluminum plate when the aluminum 
plate is pressed at the position 13", the aluminum plate pressed at the 
position 13' covers neither the contact holes 2 which should be pressed by 
the aluminum plate when the aluminum plate is pressed at the position 13 
nor the contact holes 2 which should be pressed by the aluminum plate when 
the aluminum plate is pressed at the position 13", and the aluminum plate 
pressed at the position 13" covers neither the contact holes 2 which 
should be pressed by the aluminum plate when the aluminum plate is pressed 
at the position 13 nor the contact holes 2 which should be pressed by the 
aluminum plate when the aluminum plate is pressed at the position 13'.) 
Thus, the plastic color filter (substrate) is produced. As a result of 
using the conductive particles (nickel particles) each having the diameter 
larger than the thickness of the insulating layer 3, merely by pressing a 
conductive layer such as a metal plate (aluminum plate) on the insulating 
layer 3, good electrical connection with the electrodes 1 on the film 
substrate via the contact holes 2 can be obtained through the conductive 
particles 9. 
A sixth embodiment of the present invention will now be described. 
After polystyrene particles each having a diameter of 3 .mu.m and plated by 
nickel are scattered in each contact hole 2 of the plastic film substrate 
in the first embodiment, the aluminum plate is pressed on the insulating 
layer 3 similar to the fifth embodiment. Thus, the aluminum plate 10 and 
the electrodes 1 are electrically connected through the nickel-plated 
polystyrene particles 9 as shown in FIG. 5. Then, in a method similar to 
the method described in the description of the fifth embodiment, the 
conductive color filter layers are formed on the electrodes 1, 
respectively. Thus, the plastic color filter (substrate) is produced. 
Because the nickel-plated polystyrene particles are soft, better 
electrical connection with the electrodes 1 on the film substrate via the 
contact holes 2 can be obtained through the conductive particles 9. 
A seventh embodiment will now be described. 
After polystyrene particles each having a diameter of 3 .mu.m and plated by 
nickel are scattered in each contact hole 2 of the plastic film substrate 
in the first embodiment, a conductive shield tape made by Sumitomo 3M 
Limited., instead of the aluminum plate in the sixth embodiment, is stuck 
on the insulating layer 3. Thus, the conductive shield tape 10 and the 
electrodes 1 are electrically connected through the nickel-plated 
polystyrene particles 9 as shown in FIG. 5. Then, in a method similar to 
the method described in the description of the third embodiment, the 
conductive color filter layers are formed on the electrodes 1, 
respectively. In the seventh embodiment, the conductive shield tape is 
stuck at the position 13 shown in FIG. 8 when the red color filter layers 
are formed, is stuck at the position 13' when the green color filter 
layers are formed, and is stuck at the position 13" when the blue color 
filter layers are formed. (The contact holes 2 formed on the electrodes 1 
on which the green color filter layers are formed are apart from the 
contact holes 2 formed on the electrodes 1 on which the red color filter 
layers are formed, sufficiently, so that the conductive shield tape stuck 
at the position 13' does not come into contact with the conductive shield 
tape stuck at the position 13. Similarly, the contact holes 2 formed on 
the electrodes 1 on which the blue color filter layers are formed are 
apart from the contact holes 2 formed on the electrodes 1 on which the 
green color filter layers are formed, sufficiently, so that the conductive 
shield tape stuck at the position 13" does not come into contact with the 
conductive shield tape stuck at the position 13'.) Thus, the plastic color 
filter (substrate) is produced. Because the conductive shield tape 10 uses 
a conductive adhesive layer, good electrical connection is achieved with 
the electrodes 1 on the substrate via the contact holes 2 through the 
nickel-plated polystyrene particles 9, merely as a result of the 
conductive shield tape 10 being stuck on the insulating layer 3. 
An eighth embodiment of the present invention will now be described. 
After a dry film resist of a thickness of 10 .mu.m is stuck on a glass 
substrate of a thickness of 2 mm and an area of 200 mm.sup.2, mask 
exposure and development are performed. Thus, a surface having 
irregularities having a height of 5 .mu.m with a pitch of approximately 10 
.mu.m is formed on the glass substrate. Then, an aluminum layer of a 
thickness of 1 .mu.m is formed on the surface having the irregularities of 
the substrate in an ordinary vapor deposition method. Then, as a result of 
this substrate being scribed to a strip of a width of 2 mm, a conductive 
substrate 11, such as that shown in FIG. 6, having the surface having the 
irregularities of the height of 5 .mu.m is formed. The conductive surface 
having the irregularities of the thus-formed conductive substrate is 
pressed on the insulating layer 3 of the plastic film substrate in the 
first embodiment. Thus, the conductive substrate is electrically connected 
with the electrodes 1 on the plastic film substrate via the contact holes 
2. Then, in a method similar to the method described in the description of 
the fifth embodiment, the conductive color filter layers are formed. In 
the eighth embodiment, the conductive substrate having the surface having 
the irregularities is used instead of the aluminum plate in the fifth 
embodiment. Thus, the plastic color filter (substrate) is produced. 
A ninth embodiment of the present invention will now be described. 
As a result of room-temperature-setting conductive silicon-resin paste 
being sprayed on a surface of an aluminum plate having a width of 2 mm, a 
thickness of 2 mm and a length of 200 mm, a conductive substrate 11, such 
as that shown in FIG. 6, having the surface having irregularities of a 
height of 5 .mu.m, is formed. The surface having the irregularities of the 
thus-formed conductive substrate is pressed on the insulating layer 3 of 
the plastic film substrate in the first embodiment. Thus, the conductive 
substrate is electrically connected with the electrodes 1 on the plastic 
film substrate via the contact holes 2. Then, in a method similar to the 
method described in the description of the eighth embodiment, the 
conductive color filter layers are formed. Thus, the plastic color filter 
(substrate) is produced. As a result of the irregularities of the surface 
of the conductive substrate being formed of the conductive silicon resin, 
it is possible to electrically connect with the electrodes on the plastic 
film substrate more positively. 
A tenth embodiment of the present invention will now be described. 
Similar to the ninth embodiment, a surface having irregularities is formed 
of conductive silicon resin on the conductive adhesive layer of the 
conductive shield tape made by Sumitomo 3M Limited. The surface having the 
irregularities of the conductive silicon resin of the conductive shield 
tape is stuck on the insulating layer 3 of the plastic film substrate in 
the first embodiment. Thus, the conductive shield tape is electrically 
connected with the electrodes 1 on the plastic film substrate via the 
contact holes 2. Then, in a method similar to the method described in the 
description of the seventh embodiment, the conductive color filter layers 
are formed. Thus, the plastic color filter (substrate) is produced. 
An eleventh embodiment of the present invention will now be described. 
The plastic film substrate in the first embodiment is annealed for one hour 
at 180.degree. C. so that a solvent resistance of the photoresist is 
increased. Then, nickel is plated in each contact hole 2 of the insulating 
layer 3 of the plastic film substrate so that a nickel layer having a 
thickness of 1 .mu.m is formed in the contact hole 2. The composition of 
the plating bath is nickel sulfamate, boric acid and sulfamic acid. 
Further, a value of a current during the plating is controlled to 0.01 
A/100 m.sup.2. Then, conductive paste, which is obtained as a result of 
filler (minute powder) of silver being dispersed in acrylic resin, is 
coated on the insulating layer 3 by a dispenser, and is dried at 
100.degree. C. Then, in a method similar to the method described in the 
description of the third embodiment, the conductive color filter layers 
are formed. Thus, the plastic color filter (substrate) is produced. As a 
result of performing nickel plating in each contact hole 2, the depth of 
the contact hole 2 is reduced, and the conductive paste is well stuck on 
the thus-formed nickel layers. As a result, good electrical connection 
with the electrodes 1 on the plastic film substrate can be obtained. 
A twelfth embodiment of the present invention will now be described. 
Similar to the eleventh embodiment, nickel plating is performed in each 
contact hole 2 so that a layer having a thickness of 3 .mu.m is formed. 
Then, an aluminum plate having a width of 2 mm, a thickness of 2 mm and a 
length of 200 mm is pressed at the position 13 shown in FIG. 8. Thus, the 
aluminum plate 10 is electrically connected with the electrodes 1 on the 
substrate 4 via the contact holes 2 through the nickel layers 12 formed 
through the nickel plating, as shown in FIG. 7. Then, in a method similar 
to the method described in the description of the fifth embodiment, the 
conductive color filter layers are formed. Thus, the plastic color filter 
(substrate) is produced. Thus, as a result of the metal layer being formed 
in each contact hole 2 through plating, the metal layer having a thickness 
greater than the thickness of the insulating layer 3, good electrical 
connection with the electrodes 1 on the film substrate can be obtained, 
merely as a result of a conductive layer such as a metal plate being 
pressed on the insulating layer 3. 
A thirteenth embodiment will now be described. 
After nickel plating is performed in each contact hole 2 of the plastic 
film substrate in the first embodiment, in a method similar to the method 
described in the description of the eleventh embodiment, so that a nickel 
layer of 3 .mu.m is formed, the conductive shield tape made by Sumitomo 3M 
Limited, instead of the aluminum plate in the twelfth embodiment, is stuck 
on the insulating layer 3. Thus, the conductive shield tape 10 and the 
electrodes 1 are electrically connected via the contact holes 2 through 
the nickel layers 12 formed through the plating, as shown in FIG. 7. Then, 
in a method similar to the method described in the description of the 
seventh embodiment, the conductive color filter layers are formed on the 
electrodes 1, respectively. Thus, the plastic color filter (substrate) is 
produced. Because the conductive shield tape uses a conductive adhesive 
layer, good electrical connection is obtained with the electrodes 1 on the 
plastic substrate via the contact holes 2 through the nickel layers 12, 
merely as a result of the conductive shield tape 10 being stuck on the 
insulating layer 3. 
A fourteenth embodiment of the present invention will now be described. 
After the electrode drawing-out portion is cut off from any of the plastic 
color filters (substrates) in the third through thirteenth embodiments, an 
alignment layer for liquid crystal having a thickness of 0.1 .mu.m is 
formed as a result of the agent AL3046 made by Japan Synthetic Rubber Co., 
Ltd. (JSR) being coated on the plastic color filter (substrate). Then, 
rubbing is performed and thus an alignment process is performed on the 
plastic color filter (substrate) having the alignment layer thus formed 
thereon. Then, the thus-obtained substrate and an opposite substrate, 
which has 240 stripe-shaped electrodes and has an alignment process 
performed thereon, are stuck together. Then, a liquid crystal is injected 
between the two opposite substrates. Thus, an STN (Super Twisted 
Nematic)-mode liquid-crystal cell having a twist angle of 240 degrees and 
a cell gap of 7 .mu.m is produced. The cross-sectional view of this cell 
is shown in FIG. 9. In the cross-sectional view, the plastic color filter 
substrate A in any of the third through thirteenth embodiments includes 
the plastic film substrate 4, the electrodes 1 and conductive color 
filters 8, and has an alignment layer 14 formed thereon. The opposite 
substrate B includes stripe-shaped electrodes 16 and has the alignment 
layer 14 formed thereon. After the two substrates A and B are stuck 
together, the liquid crystal 15 is injected between the two substrates A 
and B. A circuit for driving the liquid crystal is connected to the 
thus-obtained liquid crystal cell. Then, the liquid crystal cell is 
sandwiched by polycarbonate color compensators and polarizers. Thus, a 
color liquid-crystal display device is completed. The thus-obtained color 
liquid-crystal display device can perform improved color display. 
In a method for completing the color liquid-crystal display device in the 
fourteenth embodiment, the process of forming the alignment layers on the 
two substrates A and B, respectively, the alignment process performed on 
the two substrates A and B, the process of sticking the thus-obtained two 
substrates A and B together, the process of injecting the liquid crystal 
therebetween, the process of connecting the circuit for driving the liquid 
crystal to the thus-obtained liquid-crystal cell, the process of 
sandwiching the liquid-crystal cell with the polycarbonate color 
compensators and polarizers are those in accordance with a manner for 
producing a liquid-crystal display device well known in the field of 
liquid crystal display devices. 
Further, the present invention is not limited to the above-described 
embodiments, and variations and modifications may be made without 
departing from the scope of the present invention. 
The contents of the basic Japanese Patent Application No.9-254193, filed on 
Sept. 3, 1997, are hereby incorporated by reference.