U.S. patent application number 10/105389 was filed with the patent office on 2002-10-03 for transport belt, process for manufacturing the transport belt, and image-forming apparatus having the transport belt.
This patent application is currently assigned to Canon Kabushiki Kaisha. Invention is credited to Kanome, Osamu, Shimura, Shoichi, Takeuchi, Kazutaka.
Application Number | 20020142120 10/105389 |
Document ID | / |
Family ID | 18947302 |
Filed Date | 2002-10-03 |
United States Patent
Application |
20020142120 |
Kind Code |
A1 |
Takeuchi, Kazutaka ; et
al. |
October 3, 2002 |
Transport belt, process for manufacturing the transport belt, and
image-forming apparatus having the transport belt
Abstract
A transport belt comprising a base member layer formed of a film
comprised of a thermoplastic material and wound in the shape of a
belt, and a plurality of electrodes arranged at given intervals in
the shape of comb teeth on the outer periphery or inner periphery
of the first base member layer. The electrodes each comprise a
linear film comprised of a thermoplastic material and are joined by
heating onto the first base member layer. This transport belt is
improved in attraction of recording mediums and enables transport
of the recording mediums in a high accuracy. Also disclosed are a
process for its manufacture and an image-forming apparatus making
use of the same.
Inventors: |
Takeuchi, Kazutaka;
(Kanagawa, JP) ; Shimura, Shoichi; (Kanagawa,
JP) ; Kanome, Osamu; (Kanagawa, JP) |
Correspondence
Address: |
FITZPATRICK CELLA HARPER & SCINTO
30 ROCKEFELLER PLAZA
NEW YORK
NY
10112
US
|
Assignee: |
Canon Kabushiki Kaisha
Tokyo
JP
|
Family ID: |
18947302 |
Appl. No.: |
10/105389 |
Filed: |
March 26, 2002 |
Current U.S.
Class: |
428/36.9 |
Current CPC
Class: |
B29C 66/71 20130101;
B29C 66/71 20130101; B32B 27/08 20130101; Y10T 428/139 20150115;
B29C 66/71 20130101; B29C 66/71 20130101; B29C 66/03241 20130101;
B29C 66/1122 20130101; B41J 11/007 20130101; B29C 66/71 20130101;
B29L 2009/00 20130101; B29D 29/06 20130101; B29C 53/42 20130101;
B29C 66/71 20130101; B65H 5/004 20130101; B29C 66/4322 20130101;
B29C 65/18 20130101; B29C 66/71 20130101; B29C 66/71 20130101; B29C
65/02 20130101; B32B 3/02 20130101; B29C 66/71 20130101; B29C 66/71
20130101; B29C 66/71 20130101; Y10T 156/1075 20150115; B29C 66/71
20130101; B29C 66/71 20130101; B29C 66/71 20130101; B29C 66/71
20130101; B29C 66/71 20130101; B29K 2023/18 20130101; B29K 2081/04
20130101; B29K 2071/00 20130101; B29K 2023/06 20130101; B29K
2033/18 20130101; B29K 2067/003 20130101; B29K 2081/06 20130101;
B29K 2069/00 20130101; B29K 2027/12 20130101; B29K 2067/00
20130101; B29K 2067/006 20130101; B29K 2079/085 20130101; B29K
2025/06 20130101; B29K 2023/12 20130101; B29K 2077/00 20130101 |
Class at
Publication: |
428/36.9 |
International
Class: |
B32B 001/08 |
Foreign Application Data
Date |
Code |
Application Number |
Mar 28, 2001 |
JP |
092906/2001 |
Claims
What is claimed is:
1. A transport belt which comprises a first base member layer
formed of a film comprised of a thermoplastic material and wound in
the shape of a belt, and a plurality of electrodes arranged at
given intervals in the shape of comb teeth on the outer periphery
or inner periphery of the first base member layer, wherein; said
electrodes each comprise a film comprised of a thermoplastic
material, formed in a line, and are joined by heating onto the
first base member layer.
2. The transport belt according to claim 1, wherein the
thermoplastic material constituting said electrodes has a lower
volume resistivity than the volume resistivity of the thermoplastic
material constituting said first base member layer.
3. The transport belt according to claim 2, wherein the
thermoplastic material constituting said electrodes has a volume
resistivity lower which is lower than
1.0.times.10.sup.5.OMEGA..multidot.cm.
4. The transport belt according to claim 1, wherein a second base
member layer formed of a film comprised of a thermoplastic material
and wound in the shape of a belt is so provided as to hold said
electrodes between said first base member layer and the second base
member layer.
5. The transport belt according to claim 4, wherein the
thermoplastic material constituting the base member layer
positioned on the outer peripheral side in said first base member
layer and second base member layer has a volume resistivity which
is higher than the volume resistivity of the thermoplastic material
constituting said electrodes and is lower than the volume
resistivity of the thermoplastic material constituting the base
member layer positioned on the inner peripheral side in said first
base member layer and second base member layer.
6. The transport belt according to claim 4, wherein an intermediate
layer comprised of a thermoplastic material is provided at spaces
between electrodes adjoining to each other which are held between
said first base member layer and said second base member layer,
with which intermediate layer the spaces are filled up.
7. The transport belt according to claim 6, wherein the
thermoplastic material constituting said intermediate layer has the
same volume resistivity as the volume resistivity of the
thermoplastic material constituting said first base member
layer.
8. The transport belt according to any one of claims 1 to 7,
wherein the thermoplastic materials constituting the respective
layers comprise a like base material.
9. A process for producing a transport belt comprising a base
member layer formed of a film comprised of a thermoplastic material
and wound in the shape of a belt, and a plurality of electrodes
arranged at given intervals in the shape of comb teeth on the outer
periphery of the base member layer; the process comprising the
steps of: winding around a cylindrical member a sheetlike film
comprised of the thermoplastic material making up the base member
layer; arranging a plurality of linear films comprised of a
thermoplastic material making up the respective electrodes, on the
outer periphery of the sheetlike film wound around the cylindrical
member, and at given intervals in the shape of comb teeth; and
inserting into a tubular mold member the cylindrical member with
these films, followed by heating in the state that the respective
films are so held between the cylindrical member and the tubular
mold member as to be capable of being pressed against each other,
to join the sheetlike film at its ends and simultaneously join the
films to each other at their part coming into contact with each
other.
10. The process for producing a transport belt according to claim
9, wherein the thermoplastic material constituting said electrodes
has a volume resistivity which is lower than the volume resistivity
of the thermoplastic material constituting said base member
layer.
11. The process for producing a transport belt according to claim
10, wherein the thermoplastic material constituting the electrodes
has a volume resistivity which is lower than 1.0.times.10.sup.5
.mu..multidot.cm.
12. A process for producing a transport belt comprising a first
base member layer formed of a film comprised of a thermoplastic
material and wound in the shape of a belt, a plurality of
electrodes arranged at given intervals in the shape of comb teeth
on the outer periphery of the first base member layer, and a second
base member layer formed of a film comprised of a thermoplastic
material and wound in the shape of a belt, which is so provided as
to hold the electrodes between the first base member layer and the
second base member layer; the process comprising the steps of:
winding around a cylindrical member a first sheetlike film
comprised of the thermoplastic material making up the first base
member layer; arranging a plurality of linear films comprised of a
thermoplastic material making up the respective electrodes, on the
outer periphery of the first sheetlike film wound around the
cylindrical member, and at given intervals in the shape of comb
teeth; winding around the first base member layer a second
sheetlike film comprised of a thermoplastic material making up the
second base member layer; and inserting into a tubular mold member
the cylindrical member with these films, followed by heating in the
state that the respective films are so held between the cylindrical
member and the tubular mold member as to be capable of being
pressed against each other, to join each of the first and second
sheetlike films at their ends and simultaneously join the films to
each other at their part coming into contact with each other.
13. The process for producing a transport belt according to claim
12, wherein the thermoplastic material constituting said second
base member layer has a volume resistivity which is higher than the
volume resistivity of the thermoplastic material constituting said
electrodes and is lower than the volume resistivity of the
thermoplastic material constituting said first base member
layer.
14. A process for producing a transport belt comprising a first
base member layer formed of a film comprised of a thermoplastic
material and wound in the shape of a belt, a plurality of
electrodes arranged at given intervals in the shape of comb teeth
on the outer periphery of the first base member layer, a second
base member layer formed of a film comprised of a thermoplastic
material and wound in the shape of a belt, which is so provided as
to hold the electrodes between the first base member layer and the
second base member layer, and an intermediate layer comprised of a
thermoplastic material, provided at spaces between electrodes
adjoining to each other which are held between the first base
member layer and the second base member layer; the process
comprising the steps of: winding around a cylindrical member a
first sheetlike film comprised of the thermoplastic material making
up the first base member layer; winding around the first base
member layer a sheetlike film with fitting openings which is
comprised of a thermoplastic material making up the intermediate
layer and has a plurality of fitting openings arranged at given
intervals in the shape of comb teeth; fitting in the fitting
openings of the film with fitting openings a plurality of linear
films comprised of a thermoplastic material making up the
respective electrodes; winding around the film with fitting
openings a second sheetlike film comprised of a thermoplastic
material making up the second base member layer; and inserting into
a tubular mold member the cylindrical member with these films,
followed by heating in the state that the respective films are so
held between the cylindrical member and the tubular mold member as
to be capable of being pressed against each other, to join each of
the first and second sheetlike films and the film with fitting
openings at their ends and simultaneously join the films to each
other at their part coming into contact with each other.
15. The process for producing a transport belt according to claim
14, wherein the thermoplastic material constituting said second
base member layer has a volume resistivity which is higher than the
volume resistivity of the thermoplastic material constituting said
electrodes and is lower than the volume resistivity of the
thermoplastic material constituting said first base member layer,
and the thermoplastic material constituting said intermediate layer
has the same volume resistivity as the volume resistivity of the
thermoplastic material constituting said first base member
layer.
16. A process for producing a transport belt comprising a first
base member layer formed of a film comprised of a thermoplastic
material and wound in the shape of a belt, a plurality of
electrodes arranged at given intervals in the shape of comb teeth
on the outer periphery of the first base member layer, a second
base member layer formed of a film comprised of a thermoplastic
material and wound in the shape of a belt, which is so provided as
to hold the electrodes between the first base member layer and the
second base member layer, and an intermediate layer comprised of a
thermoplastic material, provided at spaces between electrodes
adjoining to each other which are held between the first base
member layer and the second base member layer; the process
comprising the steps of: winding around a cylindrical member a
first sheetlike film comprised of the thermoplastic material; the
first sheetlike film having in an integral form the part forming
the first base member layer and the part forming the intermediate
layer, having a plurality of fitting openings arranged at given
intervals in the shape of comb teeth which openings have been made
in the part forming the intermediate layer, and being so wound that
the part forming the intermediate layer is superposed on the part
forming the first base member layer; fitting in the fitting
openings of the first sheetlike film a plurality of linear films
comprised of a thermoplastic material making up the respective
electrodes; winding around the first sheetlike film with these
films a second sheetlike film comprised of a thermoplastic material
making up the second base member layer; and inserting into a
tubular mold member the cylindrical member with these films,
followed by heating in the state that the respective films are so
held between the cylindrical member and the tubular mold member as
to be capable of being pressed against each other, to join each of
the first and second sheetlike films at their ends and
simultaneously join the films to each other at their part coming
into contact with each other.
17. The process for producing a transport belt according to claim
16, wherein the thermoplastic material constituting said second
base member layer has a volume resistivity which is higher than the
volume resistivity of the thermoplastic material constituting said
electrodes and is lower than the volume resistivity of the
thermoplastic material constituting said first base member
layer.
18. An image-forming apparatus which comprises a recording means
for forming an image on a recording medium and a transport means
for transporting the recording medium, wherein; said transport
means comprises the transport belt according to claim 1, which is
rotatingly driven by a drive means, and an electrical-feed means
for feeding electricity to electrodes of said transport belt.
19. The image-forming apparatus according to claim 18, wherein said
recording means is an ink-jet recording head which ejects an ink
out of nozzles to form images.
Description
BACKGROUND OF THE INVENTION
[0001] 1. Field of the Invention
[0002] This invention relates to a transport belt used to transport
a transport object to a preset position in a high accuracy, and a
process for its manufacture. More particularly, this invention
relates to a transport belt used to transport recording mediums
such as paper and OHP film used in image-forming apparatus such as
copying machines, laser beam printers, facsimile machines, ink-jet
printers and composite machines of any of these.
[0003] 1. Related Background Art
[0004] As a conventional means for transporting such recording
mediums used in electrophotographic apparatus such as copying
machines, known is a resin belt formed of a single layer or
multiple layer having been controlled to an appropriate resistance
value the both sides of which belt is electrostatically charged to
impart electric charges to its surface so that the recording
mediums can be transported while being attracted thereto by the aid
of the electric charges.
[0005] In contrast thereto, as shown in FIG. 17, a resin belt 101
on the outer surface or inner surface of which pairs of
comb-tooth-shaped electrodes 102 and 103 are continuously formed in
the state they engage with one another leaving constant gaps 104 is
also known as disclosed in Japanese Patent Publication No.
57-58872. According to this construction, positive and negative
voltages are applied to the electrodes 102 and 103, respectively,
where a recording medium 105 is transported while being
electrostatically locally more strongly attracted to the belt. This
electrostatic-attraction transport belt provided with the
comb-tooth-shaped electrodes enables stronger attraction of the
recording medium to transport it more stably than the one which
transport the recording medium only by the aid of the charging of
the resin belt as in the above.
[0006] Ink-jet recording apparatus of a full-line type making use
of a line type recording head having a large number of ejection
orifices arranged in the width direction of recording paper to be
fed as the recording medium enable achievement of much higher
recording speed, and it is more effective to use the above
electrostatic-attraction transport belt. As an example in which
such an electrostatic-attraction transport belt is used in an
ink-jet recording apparatus, one disclosed in Japanese Patent
Application Laid-Open No. 11-151842 is available.
[0007] As methods used conventionally to manufacture transport
belts, available are a heat-melting extrusion method as typified by
blown-film extrusion (inflation) and a casting method in which a
resin or its precursor is brought into a melt which is then coated
on the inner surface and outer surface of a tubular mold in a
stated quantity, followed by removal of solvent, and thereafter
films formed are peeled.
[0008] A method is also disclosed in Japanese Patent Application
Laid-Open No. 8-187773 by the present inventors, in which a
thermoplastic sheetlike film is wound around a cylindrical member
in such a way that the film itself substantially overlaps at its
both ends, which is then covered on its outside with a tubular mold
member having a smaller coefficient of thermal expansion than the
cylindrical member, and these are heated to narrow the gap between
the cylindrical member and the tubular mold member and fuse the
sheetlike film at its both ends while pressing the ends with a
force, to manufacture a tubular film.
[0009] To manufacture such an electrostatic-attraction transport
belt provided with the comb-tooth-shaped electrodes on the outer
surface or inner surface of the belt, it is necessary to prepare
the resin belt by the heat-melting extrusion, the casting or the
manufacturing method disclosed in Japanese Patent Application
Laid-Open No. 8-187773, and join the resin belt, which serve as a
base sheet, to a sheet on which an electrode pattern has previously
been formed, or form an electrode pattern by various printing on
the resin belt formed.
[0010] Especially, recording mediums have come required to be
transported at a higher speed as the recording speed of
image-forming apparatus has been made higher. Hence, in the
conventional example in which the resin belt formed of a single
layer or multiple layer is charged so that the recording medium can
be attraction-transported, there has been a problem that the
recording medium may come apart upward from the resin belt without
completely resisting the air resistance acting on the recording
medium during its transport. As the cause thereof, it is considered
that physical external force such as vibration of the belt makes
the recording medium tend to come apart upward from the resin belt,
or that, when used in ink-jet recording apparatus, the dropping of
ink on the recording medium may temporarily lower the resistance
value of belt surface to lessen the surface electric charges which
attract the recording medium.
[0011] Accordingly, in order to achieve higher recording speed of
such ink-jet recording type image-forming apparatus, it is
preferable to use as the transport belt a composite belt like the
one described above, provided with the comb-tooth-shaped electrodes
which enable the recording medium to be strongly and continuously
electrostatically attracted to the surface of the transport
belt.
[0012] Where such a composite belt provided with the
comb-tooth-shaped electrodes is manufactured by the heat-melting
extrusion method (such as blown-film extrusion), it is usually
necessary to continuously wind up the transport belt having been
produced in a tubular form. However, when such a tubular belt is
folded when it is wound up and if any fold is made, the fold may
inevitably affect the images to be recorded on the recording
medium. On the other hand, if, in order to prevent it, the
transport belt thus produced is cut into endless belts as it is
kept tubular, a long forming line must be provided to require a
large space, resulting in a high manufacture cost.
[0013] Where the composite belt provided with the comb-tooth-shaped
electrodes is manufactured by the casting method, there is a
problem that much cost is required because the management of
concentration of solutions and the control of drying atmosphere
must accurately be made in order to obtain films with uniform
thickness and also the solvent vapor occurring in the drying step
must be disposed of.
[0014] The composite belt provided with the comb-tooth-shaped
electrodes can also be manufactured by preparing the resin belt by
the heat-melting extrusion, the casting or the manufacturing method
disclosed in Japanese Patent Application Laid-Open No. 8-187773,
and thereafter forming thereon the electrode pattern by various
printing. In such a case, however, as a matter of course, a higher
manufacture cost should result for the part corresponding to the
formation of the electrode pattern than in the case of the resin
belt prepared by the heat-melting extrusion, the casting or the
manufacturing method disclosed in Japanese Patent Application
Laid-Open No. 8-187773,
SUMMARY OF THE INVENTION
[0015] The present invention has been made taking account of the
above problems. Accordingly, an object of the present invention is
to provide a transport belt improved in attraction of recording
mediums, which is used to transport recording mediums in
image-forming apparatus.
[0016] Another object of the present invention is to provide a
process by which the transport belt improved in attraction of
recording mediums can be manufactured at a low cost.
[0017] Still another object of the present invention is to provide
an image-forming apparatus which can form recorded images with a
higher quality.
[0018] To achieve the above objects, the transport belt of the
present invention comprises a first base member layer formed of a
film comprised of a thermoplastic material and wound in the shape
of a belt, and a plurality of electrodes arranged at given
intervals in the shape of comb teeth on the outer periphery or
inner periphery of the first base member layer, wherein;
[0019] the electrodes each comprise a film comprised of a
thermoplastic material, formed in a line, and are joined by heating
onto the first base member layer.
[0020] In the transport belt of the present invention, both the
film constituting a base member layer and the film constituting
electrodes are formed of a thermoplastic material. This enables
manufacture of the transport belt with a uniform thickness without
causing any fold. Hence, the transport belt of the present
invention can be improved in attraction of recording mediums, and
enables the recording medium to be transported in a high
accuracy.
BRIEF DESCRIPTION OF THE DRAWINGS
[0021] FIG. 1 is a perspective illustration of how a sheetlike film
serving as a base member layer of a transport belt according to
First Embodiment of the present invention is wound around a
cylindrical member and a plurality of linear films serving as
electrodes are arranged on the surface of the sheetlike film.
[0022] FIG. 2 is a perspective illustration of a tubular mold
member into which the cylindrical member around which the sheetlike
film has been wound is to be inserted.
[0023] FIG. 3 is an illustration of the part where the sheetlike
film wound around the cylindrical member overlaps at its both
ends.
[0024] FIG. 4 is a see-through, perspective illustration of how the
cylindrical member around which the sheetlike film has been wound
is inserted into the tubular mold member.
[0025] FIG. 5 a perspective illustration of a heating furnace used
to heat the sheetlike film and the linear films.
[0026] FIGS. 6A, 6B and 6C illustrate the step of heating the
sheetlike film and the linear films.
[0027] FIG. 7 illustrates the step of cooling the sheetlike film
and the linear films.
[0028] FIG. 8 illustrates the whole construction of an
image-forming apparatus in which the transport belt of the present
invention is used.
[0029] FIG. 9 is a plan view showing an image-recording area of the
image-forming apparatus shown in FIG. 8.
[0030] FIG. 10 is a perspective illustration of how first and
second sheetlike films serving as base member layers of a transport
belt according to Second Embodiment of the present invention and
linear films serving as an electrode are wound around a cylindrical
member.
[0031] FIG. 11 is a see-through, perspective illustration of how
the cylindrical member around which the sheetlike film and so forth
have been wound as shown in FIG. 10 is inserted into a tubular mold
member.
[0032] FIG. 12 is a perspective illustration of how first and
second sheetlike films serving as base member layers of a transport
belt according to Third Embodiment of the present invention, linear
films serving as an electrode and a sheetlike film serving as an
intermediate layer are wound around a cylindrical member.
[0033] FIG. 13 a see-through, perspective illustration of how the
cylindrical member around which the sheetlike film and so forth
have been wound as shown in FIG. 10 is inserted into a tubular mold
member.
[0034] FIG. 14 is a plan view showing the sheetlike film serving as
an intermediate layer, shown in FIG. 12 and so forth.
[0035] FIG. 15 is a sectional view of a transport belt according to
Third Embodiment of the present invention.
[0036] FIG. 16 is a plan view showing a modification of a sheetlike
film serving as an intermediate layer in the transport belt
according to Third Embodiment of the present invention.
[0037] FIG. 17 illustrates a recording medium transport mechanism
in a conventional image-forming apparatus.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0038] The transport belt of the present invention comprises a
first base member layer formed of a film comprised of a
thermoplastic material and wound in the shape of a belt, and a
plurality of electrodes arranged at given intervals in the shape of
comb teeth on the outer periphery or inner periphery of the first
base member layer. The electrodes each comprise a film formed of a
thermoplastic material and are joined by heating onto the first
base member layer.
[0039] The transport belt of the present invention may preferably
be so constructed that the thermoplastic material constituting the
electrodes has a volume resistivity which is lower than the volume
resistivity of the thermoplastic material constituting the first
base member layer.
[0040] The transport belt of the present invention may also
preferably be so constructed that the thermoplastic material
constituting the electrodes has a volume resistivity which is lower
than 1.0.times.10.sup.5 .OMEGA..multidot.cm.
[0041] The transport belt of the present invention may still also
be so constructed that a second base member layer formed of a film
comprised of a thermoplastic material and wound in the shape of a
belt is so provided as to hold the electrodes between the first
base member layer and the second base member layer.
[0042] The transport belt of the present invention may still also
be so constructed that the thermoplastic material constituting the
base member layer positioned on the outer peripheral side in the
first base member layer and second base member layer has a volume
resistivity which is higher than the volume resistivity of the
thermoplastic material constituting the electrodes and is lower
than the volume resistivity of the thermoplastic material
constituting the base member layer positioned on the inner
peripheral side in the first base member layer and second base
member layer. This makes conducting paths more concentrate on the
outer periphery (the side to which the recording medium is
attracted) of the transport belt than the inner periphery of the
transport belt to enable stronger attraction of the recording
medium.
[0043] The transport belt of the present invention may also be so
constructed that an intermediate layer comprised of a thermoplastic
material is provided at spaces between electrodes adjoining to each
other which are held between the first base member layer and the
second base member layer, with which intermediate layer the spaces
are filled up. This makes the surface of the transport belt less
uneven, so that the images to be formed on the recording medium
transported by the transport belt can be formed in a higher image
quality.
[0044] The above transport belt of the present invention may also
be so constructed that the thermoplastic material constituting the
intermediate layer has the same volume resistivity as the volume
resistivity of the thermoplastic material constituting the first
base member layer.
[0045] The above transport belt of the present invention may still
also be so constructed that the thermoplastic materials
constituting the respective layers (films) comprise a like base
material.
[0046] The process for manufacturing the transport belt of the
present invention is a process for producing a transport belt
comprising a base member layer formed of a film comprised of a
thermoplastic material and wound in the shape of a belt, and a
plurality of electrodes arranged at given intervals in the shape of
comb teeth on the outer periphery of the base member layer; the
process comprising the steps of:
[0047] winding around a cylindrical member a sheetlike film
comprised of the thermoplastic material making up the base member
layer;
[0048] arranging a plurality of linear films comprised of a
thermoplastic material making up the respective electrodes, on the
outer periphery of the sheetlike film wound around the cylindrical
member, and at given intervals in the shape of comb teeth; and
[0049] inserting into a tubular mold member the cylindrical member
with these films, followed by heating in the state that the
respective films are so held between the cylindrical member and the
tubular mold member as to be capable of being pressed against each
other, to join the sheetlike film at its ends and simultaneously
join the films to each other at their part coming into contact with
each other.
[0050] According to the process for manufacturing the transport
belt of the present invention, the film which forms the base member
layer and the films which form the electrodes can be joined with
ease by heating these. This enables manufacture of the transport
belt having a uniform thickness without causing any fold. Hence,
the transport belt of the present invention can be improved in
attraction of recording mediums, and enables the recording medium
to be transported in a high accuracy.
[0051] The above process of the present invention may also
preferably be so constructed that the thermoplastic material
constituting the electrodes has a volume resistivity which is lower
than the volume resistivity of the thermoplastic material
constituting the base member layer.
[0052] The above process of the present invention may still also
preferably be so constructed that the thermoplastic material
constituting the electrodes has a volume resistivity which is lower
than 1.0.times.10.sup.5 .OMEGA..multidot.cm.
[0053] Another process for manufacturing the transport belt
according to the present invention is a process for producing a
transport belt comprising a first base member layer formed of a
film comprised of a thermoplastic material and wound in the shape
of a belt, a plurality of electrodes arranged at given intervals in
the shape of comb teeth on the outer periphery of the first base
member layer, and a second base member layer formed of a film
comprised of a thermoplastic material and wound in the shape of a
belt, which is so provided as to hold the electrodes between the
first base member layer and the second base member layer; the
process comprising the steps of:
[0054] winding around a cylindrical member a first sheetlike film
comprised of the thermoplastic material making up the first base
member layer;
[0055] arranging a plurality of linear films comprised of a
thermoplastic material making up the respective electrodes, on the
outer periphery of the first sheetlike film wound around the
cylindrical member, and at given intervals in the shape of comb
teeth;
[0056] winding around the first base member layer a second
sheetlike film comprised of a thermoplastic material making up the
second base member layer; and
[0057] inserting into a tubular mold member the cylindrical member
with these films, followed by heating in the state that the
respective films are so held between the cylindrical member and the
tubular mold member as to be capable of being pressed against each
other, to join each of the first and second sheetlike films at
their ends and simultaneously join the films to each other at their
part coming into contact with each other.
[0058] In the above manufacturing process, the process may be so
constructed that the thermoplastic material constituting the second
base member layer has a volume resistivity which is higher than the
volume resistivity of the thermoplastic material constituting the
electrodes and is lower than the volume resistivity of the
thermoplastic material constituting the first base member layer.
This makes conducting paths more concentrate on the outer periphery
(the side to which the recording medium is attracted) of the
transport belt than the inner periphery of the transport belt to
enable manufacture of a transport belt which can make stronger
attraction of the recording medium.
[0059] Still another process for manufacturing the transport belt
according to the present invention is a process for producing a
transport belt comprising a first base member layer formed of a
film comprised of a thermoplastic material and wound in the shape
of a belt, a plurality of electrodes arranged at given intervals in
the shape of comb teeth on the outer periphery of the first base
member layer, a second base member layer formed of a film comprised
of a thermoplastic material and wound in the shape of a belt, which
is so provided as to hold the electrodes between the first base
member layer and the second base member layer, and an intermediate
layer comprised of a thermoplastic material, provided at spaces
between electrodes adjoining to each other which are held between
the first base member layer and the second base member layer; the
process comprising the steps of:
[0060] winding around a cylindrical member a first sheetlike film
comprised of the thermoplastic material making up the first base
member layer;
[0061] winding around the first base member layer a sheetlike film
with fitting openings which is comprised of a thermoplastic
material making up the intermediate layer and has a plurality of
fitting openings arranged at given intervals in the shape of comb
teeth;
[0062] fitting in the fitting openings of the film with fitting
openings a plurality of linear films comprised of a thermoplastic
material making up the respective electrodes;
[0063] winding around the film with fitting openings a second
sheetlike film comprised of a thermoplastic material making up the
second base member layer; and
[0064] inserting into a tubular mold member the cylindrical member
with these films, followed by heating in the state that the
respective films are so held between the cylindrical member and the
tubular mold member as to be capable of being pressed against each
other, to join each of the first and second sheetlike films and the
film with fitting openings at their ends and simultaneously join
the films to each other at their part coming into contact with each
other.
[0065] This process makes the surface of the transport belt less
uneven to enable low-cost manufacture of a transport belt with
which the images to be formed on the recording medium transported
by the transport belt can be formed in a higher image quality.
[0066] In the above manufacturing process, the process may be so
constructed that the thermoplastic material constituting the second
base member layer has a volume resistivity which is higher than the
volume resistivity of the thermoplastic material constituting the
electrodes and is lower than the volume resistivity of the
thermoplastic material constituting the first base member layer,
and that the thermoplastic material constituting the intermediate
layer has the same volume resistivity as the volume resistivity of
the thermoplastic material constituting the first base member
layer.
[0067] A further process for manufacturing the transport belt
according to the present invention is a process for producing a
transport belt comprising a first base member layer formed of a
film comprised of a thermoplastic material and wound in the shape
of a belt, a plurality of electrodes arranged at given intervals in
the shape of comb teeth on the outer periphery of the first base
member layer, a second base member layer formed of a film comprised
of a thermoplastic material and wound in the shape of a belt, which
is so provided as to hold the electrodes between the first base
member layer and the second base member layer, and an intermediate
layer comprised of a thermoplastic material, provided at spaces
between electrodes adjoining to each other which are held between
the first base member layer and the second base member layer; the
process comprising the steps of:
[0068] winding around a cylindrical member a first sheetlike film
comprised of the thermoplastic material;
[0069] the first sheetlike film having in an integral form the part
forming the first base member layer and the part forming the
intermediate layer, having a plurality of fitting openings arranged
at given intervals in the shape of comb teeth which openings have
been made in the part forming the intermediate layer, and being so
wound that the part forming the intermediate layer is superposed on
the part forming the first base member layer;
[0070] fitting in the fitting openings of the first sheetlike film
a plurality of linear films comprised of a thermoplastic material
making up the respective electrodes;
[0071] winding around the first sheetlike film with these films a
second sheetlike film comprised of a thermoplastic material making
up the second base member layer; and
[0072] inserting into a tubular mold member the cylindrical member
with these films, followed by heating in the state that the
respective films are so held between the cylindrical member and the
tubular mold member as to be capable of being pressed against each
other, to join each of the first and second sheetlike films at
their ends and simultaneously join the films to each other at their
part coming into contact with each other.
[0073] This process makes the surface of the transport belt less
uneven to enable simpler and lower-cost manufacture of a transport
belt with which the images to be formed on the recording medium
transported by the transport belt can be formed in a higher image
quality.
[0074] In the above manufacturing process, the process may be so
constructed that the thermoplastic material constituting the second
base member layer has a volume resistivity which is higher than the
volume resistivity of the thermoplastic material constituting the
electrodes and is lower than the volume resistivity of the
thermoplastic material constituting the first base member
layer.
[0075] The above process of the present invention may also be so
constructed that the thermoplastic materials constituting the
respective films comprise a like base material.
[0076] Any of the above processes of the present invention may also
preferably be so constructed that the cylindrical member has a
coefficient of thermal expansion which is larger than the
coefficient of thermal expansion of the tubular mold member. This
makes gradually narrow the gap between the outer periphery of the
cylindrical member and the inner periphery of the tubular mold
member because of the difference in coefficient of thermal
expansion between the both when heated in the state the cylindrical
member with films is inserted into the tubular mold member, so that
the films standing between the both can be heated in the state the
former is tightly held between the latter.
[0077] The image-forming apparatus of the present invention
comprises a recording means for forming an image on a recording
medium and a transport means for transporting the recording medium,
wherein the transport means comprises the above transport belt of
the present invention, which is rotatingly driven by a drive means,
and an electrical-feed means for feeding electricity to the
electrodes of the transport belt. According to this image-forming
apparatus, the recording medium can be transported at a high
accuracy by means of the transport belt described above, having
been improved in attraction of recording mediums, and hence
recorded images with a higher image quality can be formed.
[0078] The apparatus of the present invention may also be so
constructed that the above recording means is an ink-jet recording
head which ejects an ink out of nozzles to form images.
[0079] Specific embodiments of the present invention are described
below with reference to the accompanying drawings.
First Embodiment
[0080] FIGS. 1 to 7 are illustrations used to describe the
construction of First Embodiment of the transport belt according to
the present invention and its manufacturing process.
[0081] As shown in FIG. 1, the transport belt according to this
embodiment has a sheetlike film 7 which forms the former's base
member layer. Used as this film is, e.g., a polyvinylidene fluoride
resin (hereinafter called "PVdF resin") film of 100 .mu.m in layer
thickness, cut into a sheet of 945 mm.times.270 mm in length and
breadth dimensions. Such dimensions may appropriately be selected
in accordance with the inner diameter of the transport belt to be
manufactured. On the surface of this sheetlike film 7, linear films
8 which form electrodes, comprised of the like PVdF resin, are
arranged in the shape of comb teeth in such a way that they are
alternately shifted in the width direction of the sheetlike
film.
[0082] A cylindrical member 6 serving as a shaft around which the
sheetlike film 7 is to be wound is also used. In this embodiment,
it is constructed in a solid rod. In this embodiment, the
cylindrical member 6 is formed of aluminum having a coefficient of
thermal expansion of 2.4.times.10.sup.-5/.degree. C., and is of
300.0 mm in diameter and 300.0 mm in length.
[0083] Meanwhile, a tubular mold member 9 shown in FIG. 2 has inner
diameter necessary for the cylindrical member 6 to be inserted
thereinto in the state the sheetlike film 7 is wound around it. In
this embodiment, it is 300.7 mm in inner diameter, 320.0 mm in
outer diameter and 300.0 mm in length. The tubular mold member 9 is
formed of stainless steel having a coefficient of thermal expansion
of 1.5.times.10.sup.-5/.degree. C.
[0084] Thus, the tubular mold member 9 has a larger coefficient of
thermal expansion than the cylindrical member 6 so that the
cylindrical member 6 and the tubular mold member 9 may come to have
a size difference of 200 .mu.m.+-.20 .mu.m between the outer
diameter of the cylindrical member 6 and the inner diameter of the
tubular mold member 9 when heated to 210.degree. C. in a heating
step described later. Also, dimensions of the cylindrical member 6
and those of the tubular mold member 9 may be determined in
accordance with the size of the sheetlike film 7.
[0085] Steps of manufacturing the transport belt of this embodiment
are described below.
[0086] First, as shown in FIG. 1, the sheetlike film 7 serving as
the base member layer is wound on the outer periphery 6a of the
cylindrical member 6 in such a way that the film itself overlaps at
its both ends 7a and 7b as shown in FIG. 3. Here, the film 7
overlaps at the both ends 7a and 7b in a width of about 4.0 mm. In
this embodiment, the sheetlike film 7 is wound on the outer
periphery 6a of the cylindrical member 6 only by one round, and
hence the sheet 7 itself is made to overlap at its both ends 7a and
7b in this way. Where, however, the sheetlike film 7 is wound on
the outer periphery 6a of the cylindrical member 6 by a plurality
of rounds, it need not necessarily be made to overlap at the both
ends 7a and 7b.
[0087] Next, as shown in FIG. 1, on the surface of the sheetlike
film 7 wound on the cylindrical member 6, linear films 8 cut in
lines of 50 .mu.m in thickness, 8 mm in width and 200 mm in length
are arranged at intervals of 3 mm one another in the shape of comb
teeth in such a way that they are alternately shifted in the width
direction of the sheetlike film 7. As a base material of the linear
films 8, the same PVdF resin as that used in the sheetlike film 7
is used, provided that particles of KETJEN BLACK (trade name),
which is high-performance conductive carbon black, are mixed in the
linear films 8 so that, while the sheetlike film 7 has a volume
resistivity of 1.0.times.10.sup.13 .OMEGA..multidot.cm, the linear
films 8 may have a volume resistivity of 1.0.times.10.sup.2
.OMEGA..multidot.cm. Hence, the linear films 8 function as
electrodes. It is nothing but an example that the linear films 8
have been made to have the volume resistivity of 1.0.times.10.sup.2
.OMEGA..multidot.cm. The linear films 8 can be made to serve as
electrodes as long as its value is smaller than 1.0.times.10 .sup.5
.OMEGA..multidot.cm. Also, the linear films 8 may have any shape as
long as they can serve as electrodes. They may be in a linear shape
as in this embodiment, or may have the shape of an elongated "T" as
shown in FIG. 17.
[0088] Subsequently, as shown in FIG. 4, the cylindrical member 6
around which the sheetlike film 7 with films 8 is kept wound is
inserted into the hollow part of the tubular mold member 9. This
assemblage is put into a heating furnace 10 shown in FIG. 5 and
heated. Conditions for the heating in the heating furnace 10 are a
heating temperature of 210.+-.5.degree. C. and a heating time of
60.+-.1 minutes. This heating time may be determined taking account
of the melting temperature of materials for the films 7 and 8 and
the state of heat deterioration. Incidentally, what is shown in
FIG. 4 is in the state the cylindrical member 6 and sheetlike film
7 inserted into the tubular mold member 9 are seen through.
[0089] When heated in the heating furnace 10, the sheetlike film 7
and the linear films 8 come worked as shown in FIGS. 6A to 6C.
[0090] As shown in FIG. 6A, before heating, there is a gap d of 350
.mu.m between the outer periphery of the cylindrical member 6 and
the inner periphery of the tubular mold member 9 because of a size
difference of 700 .mu.m between the outer diameter of the
cylindrical member 6 and the inner diameter of the tubular mold
member 9. The heating is started from this condition, whereupon the
members 6 and 9 begin expanding in accordance with their
coefficients of thermal expansion and the films 7 and 8 begin
softening with rise of temperature.
[0091] As described previously, since the aluminum which is the
material of the cylindrical member 6 has a larger coefficient of
thermal expansion than the coefficient of thermal expansion of the
stainless steel which is the materials of the tubular mold member
9, the cylindrical member 6 more expands than the tubular mold
member 9, so that, with rise of temperature, the gap d between the
outer periphery of the cylindrical member 6 and the inner periphery
of the tubular mold member 9 becomes gradually narrower than the
initial condition (see FIG. 6B).
[0092] With further progress of expansion, the gap d becomes
further narrower, until the films 7 and 8 come tightly held between
the outer periphery of the cylindrical member 6 and the inner
periphery of the tubular mold member 9. Since the sheetlike film 7
has softened on heating, its both ends 7a and 7b extend between the
outer periphery of the cylindrical member 6 and the inner periphery
of the tubular mold member 9 in the peripheral direction of these
members 6 and 7, until they fuse one another to come joined. Also,
since the sheetlike film 7 and the linear films 8 are both formed
of the like base material, they fuse one another to come into close
contact. As the result, the both ends 7a and 7b of the sheetlike
film 7 come to have no difference in height, and the gap d between
the cylindrical member 6 and the tubular mold member 9 finally
comes equal to the thickness of the films 7 and 8 (see FIG.
6C).
[0093] This embodiment has been described giving an example in
which the heating furnace 10 is used, having the most simple
construction as a heating means. Instead, a heating means employing
induction heating or lamp heater heating may also be used in order
to shorten the heating time.
[0094] After the heating step has thus been completed, the above
assemblage is cooled.
[0095] Here, the assemblage may be cooled by bringing it into
natural cooling after the heating step has been completed, but may
rapidly be cooled in order to shorten the cooling time. In this
embodiment, as shown in FIG. 7, the assemblage on which the heating
step has been completed is immersed in a liquid coolant held in a
cistern, to cool the assemblage at a cooling rate of 200.degree.
C./minute until it comes to a temperature around room
temperature.
[0096] Thereafter, the cylindrical member 6 with films is pulled
out of the tubular mold member 9, and the sheetlike film 7 with
linear films, having been wound on the outer periphery 6a of the
cylindrical member 6, is taken out. The film 7 with linear films
thus taken out has good joins between the overlapped portions 7a
and 7b and between the sheetlike film 7 and the linear films 8 to
come into a belt (tubular or cylindrical).
[0097] Thus, a transport belt 1 (see FIGS. 8 and 9) according to
this embodiment is obtained which has a base member layer formed of
the film 7 made into a belt and, provided on its surface,
electrodes 2 and 3 (see FIG. 9) formed of the linear films 8. This
transport belt has a wall thickness dimension of 100 .mu.m (the
dimension of thickness of films 7 and 8), and has a dimensional
tolerance of within .+-.10 .mu.m over the whole, having
substantially uniform wall thickness.
[0098] An ink-jet image-forming apparatus in which the transport
belt manufactured through the foregoing manufacturing process is
described below. FIG. 8 illustrates the whole construction of an
ink-jet image-forming apparatus in which the transport belt of this
embodiment is used. FIG. 9 is a plan view showing part of the
image-forming apparatus shown in FIG. 8.
[0099] As shown in FIG. 8, an image-forming apparatus 20 has a
paper pick-up section 21 in which recording mediums sheets of
recording paper 5 are piled up. The sheets of recording paper 5
piled up in the paper pick-up section 21 are so set as to be fed
sheet by sheet from the top by the rotation of a feed roller 22.
The recording paper 5 thus fed is transported by a lower transport
guide 23 to a position where it is held between a pinch roller 25
and the transport belt 1 put over a pressure roller 29. The
transport belt 1 is put over a drive roller 27, a follower roller
28 and the pressure roller 29, and is so set as to be rotatingly
driven by the drive roller 27. The transport belt 1 is rotated as
the drive roller 27 is driven, and transports the recording paper 5
to a position on a platen 26 at which the image recording is
started.
[0100] At the upper part of the platen 26, a group of recording
heads 35 which form images on the recording paper 5 are arranged
interposing the transport belt 1 between them and the platen 26.
The group of recording heads 35 consists of a recording head 35K
for black, a recording head 35C for cyan, a recording head 35M for
magenta and a recording head 35Y for yellow. These recording heads
are arranged at given intervals in order from the upstream side of
the transport direction of the recording paper 5, and are attached
to a recording head holder 35a. Also, each recording head is what
is called a full-line type recording head, which has a plurality of
recording elements over the full width of the recording area of the
recording paper 5. These recording heads are what is called ink-jet
recording heads in which the recording elements are constituted of
nozzles from ejection orifices of which the ink is ejected by a
fluid ejection means such as an electricity-heat conversion
element.
[0101] As shown in FIG. 9, charging brushes 30a and 30b are also
provided on the top surface of the transport belt at the both sides
in the direction of transportation as electrical-feed means for
applying a high voltage to each of the electrodes 2 and 3 of the
transport belt 1 so that an electrostatic force can thereby be
produced in the transport belt. Incidentally, in FIG. 9, power
sources connected to these charging brushes 30a and 30b and wirings
therefor are omitted from illustration. Also, the charging brushes
30a and 30b are constituted of a set of electrode plate and ground
plate (both not shown) which are made of conductive metal, and
positive or negative voltage is applied to a feed spot of the
electrode plate. A feed spot of the ground plate is grounded.
[0102] In the image-forming apparatus 20 constructed as described
above, the recording paper 5 fed onto the transport belt 1 is
attracted onto the transport belt by the action of static
electricity produced across the electrodes 2 and 3 of the transport
belt 1 by charging with the brushes 30a and 30b, and is transported
by the transport belt 1 while images are formed by the recording
heads 25.
[0103] The recording paper 5 on which the images have been formed
is delivered while being held between an output roller 36 and a
spur 37 which is a rotator provided in pressure contact with the
former, and outputted to an output tray 38.
[0104] In the transport belt 1 of this embodiment, since both the
sheetlike film 7 which forms the base member layer and the linear
films 8 which form the electrodes are comprised of the
thermoplastic material, the both can readily be joined by heating
them. This enables manufacture of the transport belt in a uniform
thickness without causing any fold. Thus, the transport belt 1 of
this embodiment can be improved in attraction of the recording
medium 5, and enables the recording medium 5 to be transported in a
high accuracy.
[0105] In the foregoing, what has been shown is an example in which
the linear films 8 which form the electrodes are arranged on the
surface of the sheetlike film 7 which forms the base member layer.
Conversely, the transport belt may also be so constructed that the
linear films 8 which form the electrodes are arranged on the back
of the sheetlike film 7 which forms the base member layer. In such
a case, it may be manufactured in the above manufacturing process
by arranging a plurality of linear films 8 on the outer periphery
6a of the cylindrical member 6 in the shape of comb teeth and
winding the sheetlike film 7 thereon.
[0106] Materials applicable in the respective members used in this
embodiment are described below.
[0107] As the thermoplastic material (thermoplastic resin material)
which forms the sheetlike film 7 and the linear films 8, usable are
polyethylene, polypropylene, polymethylpentene-1, polystyrene,
polyamide, polycarbonate, polysulfone, polyarylate, polyethylene
terephthalate, polybutylene terephthalate, polyphenylene sulfide,
polyether sulfone, polyether nitrile, various fluorine resins,
thermoplastic polyimide materials, polyether ether ketone,
thermotropic liquid-crystal polymers and polyamic acid, as well as
alloy resins obtained by compounding or mixing any of these
thermoplastic resins in a desired proportion. In particular,
systems in which ion-conductive polymers have been blended for the
purpose of controlling conductivity and so forth are also most
suitable. Also usable are those in which at least one organic or
inorganic fine powder has been compounded for the purpose of
providing the above resin materials with heat-resistant
reinforcement, conductivity and heat-conducting properties.
[0108] Here, as the organic fine powder, condensation polyimide
powder is preferred. As the inorganic fine powder, inorganic
spherical fine particles such as carbon black powder, magnesium
oxide powder, magnesium fluoride powder, silicon oxide powder,
aluminum oxide powder and titanium oxide powder, and fibrous
particles such as carbon fiber and glass fiber, and wiskery powders
such as potassium 6-titanate, potassium 8-titanate, silicon carbide
and silicon nitride are preferred.
[0109] In this embodiment, an example in which aluminum is used as
the material of the cylindrical member 6 has been given, and an
example in which stainless steel is used as the material of the
tubular mold member 9 has been given. Besides these materials,
combination of a resin material such as polytetrafluoroethylene
with a glass material may also be used.
Second Embodiment
[0110] FIGS. 10 and 11 are illustrations used to describe Second
Embodiment of the transport belt according to the present
invention. In FIGS. 10 and 11, the same components as those in
First Embodiment are denoted by the same reference numerals as
those. The transport belt of this embodiment is characterized in
that linear films 8 which form comb-tooth-shaped electrodes are
provided between two sheetlike films 7 and 11 so that the belt can
have a stronger attraction transport power.
[0111] A cylindrical member 6 in this embodiment is also made of
aluminum and a tubular mold member 9 is also made of stainless
steel. These are made to have the same coefficients of thermal
expansion and component dimensions as those in First
Embodiment.
[0112] Steps of manufacturing the transport belt of this embodiment
are described below.
[0113] First, as shown in FIG. 10, a first sheetlike film 7 which
forms a first base member layer, comprised of thermoplastic PVdF
resin and provided in the same length and breadth dimensions as the
case of First Embodiment, is wound on the outer periphery 6a of the
cylindrical member 6 in such a way that the film itself overlaps at
its both ends. Also, in this embodiment, the sheetlike film 7 has a
thickness of 50 .mu.m.
[0114] Next, as shown in FIG. 10, on the surface of the sheetlike
film 7 wound on the cylindrical member 6, thermoplastic linear
films 8 cut in lines of 50 .mu.m in thickness, 6 mm in width and
200 mm in length are arranged at intervals of 3 mm one another in
the shape of comb teeth in such a way that they are alternately
shifted in the width direction of the sheetlike film 7. The films 8
are then thermocompression bonded by means of a 170.degree. C. hot
plate to attach them provisionally to the film 7. As a base
material of the linear films 8, like First Embodiment, the PVdF
resin is used in which particles of KETJEN BLACK (trade name),
which is high-performance conductive carbon black, are mixed.
[0115] Subsequently, on the first sheetlike film 7 with films 8, a
thermoplastic, second sheetlike film 11 of 50 .mu.m in layer
thickness, cut into a sheet of 945 mm.times.230 mm in length and
breadth dimensions, which forms a second base member layer is so
wound by one round that it holds the linear films 8 between it and
the film 7. Here, the sheetlike film 11 is made to overlap at its
both ends in a width of 4 mm.
[0116] In this embodiment, the sheetlike films 7 and 11 and linear
films 8 have volume resistivities set in the following way. First,
the first sheetlike film 7 and linear films 8 are made to have a
volume resistivity of 1.0.times.10.sup.13 .OMEGA..multidot.cm and a
volume resistivity of 1.0.times.10.sup.2 .OMEGA..multidot.cm,
respectively, like those in First Embodiment. As for the second
sheetlike film 11, it is made to have a volume resistivity of
1.0.times.10.sup.10 .OMEGA..multidot.cm, which is a value of a
little lower resistance (a lower dielectric) than the first
sheetlike film 7 so that electric charges may readily be generated
on the top surface of the transport belt 1. The second sheetlike
film 11 is formed of a material comprising PVdF resin compounded
appropriately with an ion conductive polymer, in order to make the
film 11 have a lower resistivity than the first sheetlike film
7.
[0117] Subsequently, as shown in FIG. 11, the cylindrical member 6
around which these films 7 and 11 with films 8 are kept wound is
inserted into the hollow part of the tubular mold member 9. This
assemblage is heated and then cooled by the same means as those in
First Embodiment. As the result, the respective sheetlike films 7
and 8 themselves join at their overlapped portions and
simultaneously the films 7, 8 and 11 join to each other at their
part coming into contact with each other. Thus, a transport belt of
triple-layer structure consisting of the sheetlike films 7 and 11
and the linear films 8 is obtained.
[0118] The transport belt of this embodiment has been used as the
transport belt of the image-forming apparatus shown in FIGS. 8 and
9, where it has been ascertained that this transport belt can
attain attraction about twice the attraction attained by the
transport belt of First Embodiment when an A4-size OHP sheet is
used as the recording medium to be transported. The reason therefor
is considered as follows: In the case of the transport belt of
First Embodiment, the electrodes 2 and 3 have only equal conducting
paths between them, and hence only weak electric current flows
across the positive and negative electrodes 2 and 3, so that only
slight electric charges have been generated on the surface. On the
other hand, the transport belt of this embodiment has on the
attracting-surface side the second sheetlike film 11, which has
lower volume resistivity than the first sheetlike film 7, and hence
the conducting paths have concentrated on the attracting-surface
side, so that more electric charges can be generated on the
attracting surface.
Third Embodiment
[0119] FIGS. 12 and 13 are illustrations used to describe Third
Embodiment of the transport belt according to the present
invention. In FIGS. 12 and 13, the same components as those in
First Embodiment are denoted by the same reference numerals as
those. The transport belt of this embodiment is characterized in
that the transport belt having the comb-tooth-shaped electrodes are
improved in its surface smoothness (in particular, surface profile)
so that the belt can have a stronger attraction transport power and
also the recording medium can be transported at a high accuracy to
achieve higher image quality of the images to be recorded by means
of the image-forming apparatus.
[0120] A cylindrical member 6 in this embodiment is also made of
aluminum and a tubular mold member 9 is also made of stainless
steel. These are made to have the same coefficients of thermal
expansion and component dimensions as those in First Embodiment
except that the tubular mold member 9 has an inner diameter of
300.8 mm.
[0121] Steps of manufacturing the transport belt of this embodiment
are described below.
[0122] First, as shown in FIG. 12, a first sheetlike film 7 which
forms a first base member layer, comprised of thermoplastic PVdF
resin and provided in the same length and breadth dimensions as the
case of First Embodiment, is wound on the outer periphery 6a of the
cylindrical member 6 in such a way that the film itself overlaps at
its both ends. Also, in this embodiment, the sheetlike film 7 has a
thickness of 50 .mu.m.
[0123] Next, on this film 7, a sheetlike film 12 which forms an
intermediate layer comprised of the same material, and has the same
volume resistivity, as the film 7 is so wound by one round that the
film 12 itself overlap at its both ends. This sheetlike film 12 has
the same length and breadth dimensions as the first sheetlike film
7, provided that, as shown in FIG. 14, the sheetlike film 12 is
provided with a plurality of fitting openings 13 in which linear
films 8 described later are to be fitted; the openings being
arranged at intervals of 3 mm in the shape of comb teeth in such a
way that they are alternately shifted in the width direction of the
sheetlike film 12. These fitting openings 13 are formed in the film
12 by means of a punching tool and a film set jig (both not shown);
the openings being so formed as to be 6 mm in width and 200 mm in
length.
[0124] Next, as shown in FIG. 12, thermoplastic linear films 8 cut
in lines of 50.mu.m in thickness, 6 mm in width and 200 mm in
length are fitted in the fitting openings 13 of the film 12 wound
on the cylindrical member 6. As a base material of the linear films
8, like First Embodiment, the PVdF resin is used in which particles
of KETJEN BLACK (trade name), which is high-performance conductive
carbon black, are mixed.
[0125] Subsequently, on the first sheetlike film 12, a
thermoplastic, second sheetlike film 11 of 50 .mu.m in layer
thickness, cut into a sheet of 945 mm.times.230 mm in length and
breadth dimensions, which forms a second base member layer is wound
by one round. Here, the sheetlike film 11 is made to overlap at its
both ends in a width of 4 mm.
[0126] In this embodiment, the sheetlike films 7, 11 and 12 and
linear films 8 have volume resistivities set in the following way.
First, the first sheetlike film 7 and the sheetlike film 12 which
forms the intermediate layer are made to have a volume resistivity
of 1.0.times.10.sup.13 .OMEGA..multidot.cm, and the linear films 8
are made to have a volume resistivity of 1.0.times.10.sup.2
.OMEGA..multidot.cm. As for the second sheetlike film 11, it is
made to have a volume resistivity of 1.0.times.10.sup.10
.OMEGA..multidot.cm in the same manner as in Second Embodiment.
[0127] Incidentally, FIGS. 12 and 13 show an example in which the
respective sheetlike films 7, 11 and 12 themselves each overlap at
the like position with respect to the position in the peripheral
direction of the cylindrical member 6. These, however, may overlap
at any position in the peripheral direction. For example, in order
to make the transport belt having been completed have a higher
thickness uniformity, the sheetlike films 7, 11 and 12 may be made
to overlap at positions appropriately scattered in the peripheral
direction of the cylindrical member 6.
[0128] Subsequently, as shown in FIG. 13, the cylindrical member 6
around which these films 7, 11 and 12 with films 8 are kept wound
is inserted into the hollow part of the tubular mold member 9. This
assemblage is heated and then cooled by the same means as those in
First Embodiment. As the result, the respective sheetlike films 7,
11 and 12 themselves join at their overlapped portions and
simultaneously the films 7, 8, 11 and 12 join to each other at
their part coming into contact with each other. Thus, a transport
belt of triple-layer structure consisting of the sheetlike films 7,
11 and 12 and the linear films 8 is obtained. A sectional view of
this transport belt along the peripheral direction is shown in FIG.
15.
[0129] The transport belt of this embodiment has been used as the
transport belt of the image-forming apparatus shown in FIGS. 8 and
9, where it has been ascertained that this transport belt can
attain attraction about twice the attraction attained by the
transport belt of First Embodiment when an A4-size OHP sheet is
used as the recording medium to be transported. The mechanism by
which this can be attained is considered to be the same as the
mechanism explained in Second Embodiment. In addition, the
transport belt of this embodiment is so constructed that the
electrode films 8 have been fitted in the fitting openings 13 of
the film 12. Hence, the sheetlike film 12 which forms the
intermediate layer also comprised of a thermoplastic material,
which is present in the spaces lying between the linear films 8 one
another between the first sheetlike film 7 and the second sheetlike
film 11, makes any unevenness not appear at the transport belt
surface to make the surface uniform. As the result, the ink-shot
position on the recording medium being transported by this
transport belt can be improved in accuracy, and hence recorded
images with a higher image quality can be formed.
Fourth Embodiment
[0130] FIG. 16 is a plan view of a sheetlike film used as a
modification of the sheetlike film shown in FIG. 15.
[0131] The sheetlike film 7' used in this modification has a shape
that the part corresponding to the first sheetlike film 7 which
forms the first base member layer, shown in FIG. 12, and the part
corresponding to the sheetlike film 12 which forms the intermediate
layer are linked in a single sheet. Accordingly, the sheetlike film
7' has a length for the first sheetlike film 7 and sheetlike film
12 put together, and a plurality of fitting openings 13 are formed
only in the part corresponding to the sheetlike film 12 having a
length which is half of the total length.
[0132] This sheetlike film 7' is wound in the following way. First,
its part not provided with the fitting openings 13 (the part
corresponding to the first sheetlike film 7) is wound by one round
on the outer periphery 6a of the cylindrical member 6 (see FIG.
12). Then, its part provided with the fitting openings 13 (the part
corresponding to the sheetlike film 12) is superposingly wound
thereon. Accordingly, while two steps are required to wind the
sheetlike films 7 and 12 which form the base member layer and the
intermediate layer, respectively, in the example shown in FIG. 12,
the sheetlike film 7' which forms both the base member layer and
the intermediate layer can be wound in one step in this
modification. This enables cost reduction in the manufacture of
transport belts.
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