U.S. patent application number 12/056763 was filed with the patent office on 2008-10-02 for solvent absorbing device and image forming apparatus.
Invention is credited to Gentaro Furukawa, Toshiya Kojima.
Application Number | 20080236480 12/056763 |
Document ID | / |
Family ID | 39792109 |
Filed Date | 2008-10-02 |
United States Patent
Application |
20080236480 |
Kind Code |
A1 |
Furukawa; Gentaro ; et
al. |
October 2, 2008 |
SOLVENT ABSORBING DEVICE AND IMAGE FORMING APPARATUS
Abstract
The solvent absorbing device includes: a hollow open roller
composed of a cylindrical member of which inner side is divided
into at least a first space and a second space in such a manner
that a cross-section of the cylindrical member in a plane
perpendicular to an axial direction of the cylindrical member is
divided into a plurality of regions, the cylindrical member having
a first opening section and a second opening section passing from
an outer surface of the cylindrical member to an inner surface of
the cylindrical member and opening respectively to the first space
and the second space; a cylindrical absorbing body which is
arranged over the outer surface of the cylindrical member and is
rotatable in a rotational direction relatively to the hollow open
roller; and a pressure application device which applies a negative
pressure to the first space of the hollow open roller, and applies
a prescribed pressure to the second space of the hollow open
roller. The first and second opening sections are disposed other
than a position facing a portion of a surface of the absorbing body
making in contact with solvent, and the first opening section is
disposed on an upstream side of the second opening section in terms
of the rotational direction of the absorbing body.
Inventors: |
Furukawa; Gentaro;
(Kanagawa-ken, JP) ; Kojima; Toshiya;
(Kanagawa-ken, JP) |
Correspondence
Address: |
BIRCH STEWART KOLASCH & BIRCH
PO BOX 747
FALLS CHURCH
VA
22040-0747
US
|
Family ID: |
39792109 |
Appl. No.: |
12/056763 |
Filed: |
March 27, 2008 |
Current U.S.
Class: |
118/50 |
Current CPC
Class: |
C23C 26/02 20130101;
B41J 2/0057 20130101 |
Class at
Publication: |
118/50 |
International
Class: |
C23C 26/00 20060101
C23C026/00 |
Foreign Application Data
Date |
Code |
Application Number |
Mar 29, 2007 |
JP |
2007-089621 |
Claims
1. A solvent absorbing device, comprising: a hollow open roller
composed of a cylindrical member of which inner side is divided
into at least a first space and a second space in such a manner
that a cross-section of the cylindrical member in a plane
perpendicular to an axial direction of the cylindrical member is
divided into a plurality of regions, the cylindrical member having
a first opening section and a second opening section passing from
an outer surface of the cylindrical member to an inner surface of
the cylindrical member and opening respectively to the first space
and the second space; a cylindrical absorbing body which is
arranged over the outer surface of the cylindrical member and is
rotatable in a rotational direction relatively to the hollow open
roller; and a pressure application device which applies a negative
pressure to the first space of the hollow open roller, and applies
a prescribed pressure to the second space of the hollow open
roller, wherein the first and second opening sections are disposed
other than a position facing a portion of a surface of the
absorbing body making in contact with solvent, and the first
opening section is disposed on an upstream side of the second
opening section in terms of the rotational direction of the
absorbing body.
2. The solvent absorbing device as defined in claim 1, wherein the
pressure application device applies a negative pressure to the
second space.
3. The solvent absorbing device as defined in claim 1, wherein the
pressure application device applies a positive pressure to the
second space.
4. The solvent absorbing device as defined in claim 3, further
comprising a heating device which heats air to be supplied to the
second space.
5. The solvent absorbing device as defied in claim 1, wherein: the
cylindrical member further has a third space in the inner side and
a third opening section opening to the third space; the third
opening section is disposed on a downstream side of the first
opening section and the upstream side of the second opening section
in terms of the rotational direction of the absorbing body; and the
solvent absorbing device further comprises a liquid deposition
device which deposits a prescribed liquid onto the surface of the
absorbing body and is arranged at a position facing the third
opening section through the absorbing body.
6. The solvent absorbing device as defined in claim 1, wherein the
cylindrical member further has a liquid storage section in the
inner side, collected excess solvent being accumulated in the
liquid storage section.
7. An image forming apparatus comprising the solvent absorbing
device as defined in claim 1.
Description
BACKGROUND OF THE INVENTION
[0001] 1. Field of the Invention
[0002] The present invention relates to a solvent absorbing device
and to an image forming apparatus, and more particularly, to a
solvent absorbing device and an image forming apparatus whereby
excess solvent on a medium is collected by rotating a cylindrical
absorbing body.
[0003] 2. Description of the Related Art
[0004] In general, an inkjet recording apparatus performs recording
by ejecting ink droplets toward a recording medium from a plurality
of nozzles, which are formed in a recording head (inkjet head). The
inkjet recording apparatus is widely used due to its excellence
low-noise performance, low running costs, and the fact that it is
capable of recording images of high quality onto recording media of
various different types. The ink ejection methods include, for
example, a piezoelectric method, which uses the displacement of a
piezoelectric element, a thermal method, which uses thermal energy
generated by a heating element, and the like.
[0005] In the inkjet recording apparatus, an ink of relatively low
viscosity is used due to the ejection system, and it is then
necessary to remove the excess solvent (generally, water or the
like) from the recording medium on which the ink has been
deposited. If the excess solvent is not removed sufficiently, then
problems are liable to occur, such as bleeding of the recorded
image, wrinkling of the recording medium, and the like. In
particular, when using a non-permeable medium (for example,
plastic, metal, glass, or the like) as the recording medium,
bleeding is liable to occur in the recorded image, and this may
cause deterioration of image quality.
[0006] There is an inkjet recording apparatus based on an
intermediate transfer method, in which an image is formed on an
intermediate transfer body by depositing ink from a recording head
and the image is then transferred to a recording medium. Even in
the recording apparatus of this kind, there is a problem in that a
satisfactory transferred image cannot be obtained unless the excess
solvent on the intermediate transfer body is removed
satisfactorily.
[0007] There is an inkjet recording apparatus based on a two-liquid
reaction method, which uses an ink and a treatment liquid causing
an aggregating reaction of the coloring material in the ink, and
mixes and causes the reaction of the ink and the treatment liquid
on the medium (the recording medium or the intermediate transfer
body). In the inkjet recording apparatus based on the two-liquid
reaction method particular, since a large amount of solvent is
deposited on the surface of the medium, then the aforementioned
problems caused by the excess solvent are even more liable to
occur.
[0008] In order to resolve the above-described problems, various
technologies have been proposed thus far in order to remove excess
solvent from the surface of the medium, such as the recording
medium or the intermediate transfer body (see, for example,
Japanese Patent Application Publication Nos. 2001-179959 and
2002-023504).
[0009] Japanese Patent Application Publication No. 2001-179959
discloses a liquid solvent absorbing body that absorbs liquid
solvent through an ink absorbing body making contact with the ink.
A ventilation device is provided inside the liquid solvent
absorbing body, whereby the liquid solvent absorbed by the
absorbing body can escape from the inner side of the body. However,
this is problematic in that since the air flows into the absorbing
body from all sides, then the suction force is low and it is
difficult to collect the excess solvent, unless the surface of the
absorbing body is sealed with liquid, or the like.
[0010] Japanese Patent Application Publication No. 2002-023504
discloses a liquid removal apparatus that collects a development
solution. This liquid removal apparatus has a porous cylinder and a
shielding body, which is not permeable to air and arranged at a
position inside the porous cylinder where it makes contact with the
liquid, and the liquid is collected by reducing the pressure inside
the porous cylinder. However, although this resolves the problems
associated with Japanese Patent Application Publication No.
2001-179959, since it is only able to suction from a part of the
porous body, then while it is possible to collect the excess
solvent, it is not possible to dry the porous body sufficiently. If
the porous body is not dried sufficiently, then the absorption
performance of the porous body is reduced, and the excess solvent
cannot be collected adequately.
SUMMARY OF THE INVENTION
[0011] The present invention has been contrived in view of these
circumstances, an object thereof being to provide a solvent
absorbing device and an image forming apparatus whereby there is no
decline in the excess solvent absorption performance and excess
solvent can be collected reliably.
[0012] In order to attain the aforementioned object, the present
invention is directed to a solvent absorbing device, comprising: a
hollow open roller composed of a cylindrical member of which inner
side is divided into at least a first space and a second space in
such a manner that a cross-section of the cylindrical member in a
plane perpendicular to an axial direction of the cylindrical member
is divided into a plurality of regions, the cylindrical member
having a first opening section and a second opening section passing
from an outer surface of the cylindrical member to an inner surface
of the cylindrical member and opening respectively to the first
space and the second space; a cylindrical absorbing body which is
arranged over the outer surface of the cylindrical member and is
rotatable in a rotational direction relatively to the hollow open
roller; and a pressure application device which applies a negative
pressure to the first space of the hollow open roller, and applies
a prescribed pressure to the second space of the hollow open
roller, wherein the first and second opening sections are disposed
other than a position facing a portion of a surface of the
absorbing body making in contact with solvent, and the first
opening section is disposed on an upstream side of the second
opening section in terms of the rotational direction of the
absorbing body.
[0013] According to this aspect of the present invention, it is
possible to promote the collection of the excess solvent by the
absorbing body through the first opening section corresponding to
the first space, due to the negative pressure applied to the first
space, as well as being able to dry the absorbing body through the
second opening section corresponding to the second space, at the
downstream side in terms of the rotational direction of the
absorbing body, due to the prescribed pressure applied to the
second space. In other words, in the absorbing body rotating over
the outer side of the hollow open roller, the solvent collection
and the drying are repeated alternately, and consequently there is
no decline in the absorptive properties of the absorbing body and
it is possible to collect the excess solvent continuously in a
reliable manner, while maintaining a prescribed absorption
performance.
[0014] Preferably, the pressure application device applies a
negative pressure to the second space.
[0015] According to this aspect of the present invention, it is
possible to collect the excess solvent contained in the absorbing
body reliably to the inner side (the side of the second space),
without the excess solvent being expelled to the outer side, and
therefore the absorbing body can be dried in a reliable manner.
[0016] It is also preferable that the pressure application device
applies a positive pressure to the second space.
[0017] According to this aspect of the present invention, since
foreign material adhering to the surface of the absorbing body can
be blow out from the inner side toward the outer side, as well as
the excess solvent contained in the absorbing body, then it is
possible to prevent blockages as well as drying the absorbing
body.
[0018] Preferably, the solvent absorbing device further comprises a
heating device which heats air to be supplied to the second
space.
[0019] According to this aspect of the present invention, it is
possible to promote the evaporation of the excess solvent contained
in the absorbing body, as well as being able to lower the viscosity
of the excess solvent, and therefore the excess solvent can be
blown out readily to the outer side of the absorbing body and the
absorbing body can be dried in a more reliable fashion.
[0020] Preferably, the cylindrical member further has a third space
in the inner side and a third opening section opening to the third
space; the third opening section is disposed on a downstream side
of the first opening section and the upstream side of the second
opening section in terms of the rotational direction of the
absorbing body; and the solvent absorbing device further comprises
a liquid deposition device which deposits a prescribed liquid onto
the surface of the absorbing body and is arranged at a position
facing the third opening section through the absorbing body.
[0021] According to this aspect of the present invention, the
liquid deposited on the surface of the absorbing body by the liquid
deposition device is absorbed into the absorbing body by means of
the third opening section corresponding to the third space, due to
the negative pressure applied to the third space, and therefore it
is possible to lower the viscosity of the excess solvent contained
in the absorbing body. Consequently, the absorbing body can be
dried in a more reliable fashion, to the downstream side in terms
of the direction of rotation of the absorbing body.
[0022] If a cleaning liquid is deposited by the liquid deposition
device, then it is possible to remove foreign matter adhered to the
absorbing body, as well as being able to prevent blockages.
[0023] Preferably, the cylindrical member further has a liquid
storage section in the inner side, collected excess solvent being
accumulated in the liquid storage section.
[0024] According to this aspect of the present invention, since
there is no need to provide a separate container for storing the
excess solvent that has been collected, then space savings can be
made.
[0025] In order to attain the aforementioned object, the present
invention is also directed to an image forming apparatus comprising
the above-described solvent absorbing device.
[0026] According to the present invention, it is possible to
promote the collection of the excess solvent by the absorbing body
through the first opening section corresponding to the first space,
due to the negative pressure applied to the first space, as well as
being able to dry the absorbing body through the second opening
section corresponding to the second space, at the downstream side
in terms of the rotational direction of the absorbing body, due to
the prescribed pressure applied to the second space. In other
words, in the absorbing body rotating over the outer side of the
hollow open roller, the solvent collection and the drying are
repeated alternately, and consequently there is no decline in the
absorptive properties of the absorbing body and it is possible to
collect the excess solvent continuously in a reliable manner, while
maintaining a prescribed absorption performance.
BRIEF DESCRIPTION OF THE DRAWINGS
[0027] The nature of this invention, as well as other objects and
advantages thereof, will be explained in the following with
reference to the accompanying drawings, in which like reference
characters designate the same or similar parts throughout the
figures and wherein:
[0028] FIG. 1 is a schematic drawing showing a composition of an
inkjet recording apparatus according to an embodiment of the
present invention;
[0029] FIG. 2 is a principal block diagram showing a system
configuration of the inkjet recording apparatus;
[0030] FIGS. 3A and 3B are schematic drawings showing compositions
of inkjet recording apparatuses according to embodiments of the
present invention;
[0031] FIG. 4 is a schematic drawing showing a composition of a
solvent absorbing device according to a first embodiment;
[0032] FIGS. 5A and 5B are external perspective diagrams including
partial cross-sections showing compositions of solvent absorbing
rollers;
[0033] FIG. 6 is a schematic drawing showing a composition of a
solvent absorbing device according to a second embodiment;
[0034] FIG. 7 is a schematic drawing showing a composition of a
solvent absorbing device according to a third embodiment;
[0035] FIG. 8 is a schematic drawing showing a composition of
another solvent absorbing device according to the third
embodiment;
[0036] FIG. 9 is a schematic drawing showing a composition of a
solvent absorbing device according to a fourth embodiment;
[0037] FIG. 10 is a schematic drawing showing a composition of
another solvent absorbing device according to the fourth
embodiment;
[0038] FIG. 11 is a schematic drawing showing a composition of yet
another solvent absorbing device according to the fourth
embodiment;
[0039] FIG. 12 is a schematic drawing showing a composition of a
solvent absorbing device according to a fifth embodiment; and
[0040] FIG. 13 is a schematic drawing showing a composition of a
solvent absorbing device according to a sixth embodiment.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
Image Forming Apparatus
[0041] FIG. 1 is a schematic drawing showing a composition of an
inkjet recording apparatus according to an embodiment of an image
forming apparatus relating to the present invention.
[0042] The inkjet recording apparatus 10 shown in FIG. 1 is based
on an intermediate transfer method, in which an image is formed on
an endless belt-shaped intermediate transfer body 12 and the image
is then transferred to a recording medium 14. The intermediate
transfer body 12 is made of a non-permeable material (for example,
a polyimide film, urethane rubber, silicone rubber, or the like).
It is also possible to make only the layer on the outer surface of
the intermediate transfer body 12 (the side on which the ink is
deposited), from a non-permeable material.
[0043] In FIG. 1, the intermediate transfer body 12 is configured
to be wound about the exterior of three rollers 16, 18 and 20. The
first roller 16 is a drive roller, to which the motive force of a
drive motor 48 (see FIG. 2) is transmitted, and the second roller
18 and the third roller 20 are idle rollers, which rotate due to
the movement of the intermediate transfer body 12. When the first
roller 16 rotates due to the driving of the drive motor 48, the
intermediate transfer body 12 turns in the counter-clockwise
direction in FIG. 1 (hereinafter, called the "direction of rotation
of the transfer body") due to the rotation of the first roller
16.
[0044] A plurality of recording heads 22 (22K, 22C, 22M and 22Y),
which correspond to colored inks of black (K), cyan (C), magenta
(M) and yellow (Y), respectively, are arranged in sequence from the
upstream side in the direction of rotation of the transfer body, at
positions facing the outer circumferential surface of the
intermediate transfer body 12, between the first roller 16 and the
second roller 18.
[0045] The recording heads 22 (22K, 22C, 22M and 22Y) are
configured as long full-line heads, in each of which a plurality of
nozzles are arranged through the maximum recordable width in the
breadthways direction of the intermediate transfer body 12 (the
direction perpendicular to the direction of rotation of the
transfer body; the direction of the lo obverse-reverse of the sheet
containing FIG. 1). The colored irks (K, C, M, Y) are ejected as
droplets from the corresponding nozzles.
[0046] It is possible to record an image on the whole surface of
the intermediate transfer body 12 by means of just one operation of
relatively moving the intermediate transfer body 12 and the
recording heads 22 with respect to each other, in the direction of
rotation of the transfer body, without moving the recording heads
22 in the breadthways direction of the intermediate transfer body
12. Therefore, the recording speed can be raised. Higher-speed
printing is thereby made possible and productivity can be improved
in comparison with a shuttle type head configuration, in which a
recording head reciprocates in the direction orthogonal to the
paper conveyance direction (the main scanning direction).
[0047] Of course, the present invention can also be applied to a
serial type of recording apparatus, which records an image on an
intermediate transfer body 12 while moving a recording head of
short dimensions (a serial head) reciprocally in the breadthways
direction of the intermediate transfer body 12.
[0048] The ejection method of the recording heads 22 uses a
piezoelectric method whereby droplets of the inks are ejected from
the nozzles by pressurizing the inks inside the pressure chambers
by utilizing the displacement of piezoelectric elements, or a
thermal method whereby bubbles are generated in the inks inside
pressure chambers (also called bubble chambers) by using the
thermal energy created by heating elements, and droplets of the
inks are ejected from the nozzles due to the pressure caused by the
growth of the bubbles. Other types of ejection methods may also be
used.
[0049] A platen 24 serving as a supporting member for the
intermediate transfer body 12 is disposed at a position facing the
recording heads 22 across the intermediate transfer body 12.
[0050] The droplets of the inks are ejected from the recording
heads 22 in a state where at least the portion of the surface of
the intermediate transfer body 12 that opposes the recording heads
22 is kept flat by the platen 24.
[0051] A solvent removing roller 50 to which the present invention
is applied is disposed on the downstream side from the recording
head 22Y in terms of the direction of rotation of the transfer
body, in such a manner that the solvent removing roller 50
substantially makes contact with the outer surface of the
intermediate transfer body 12. The solvent removing roller 50 is a
solvent removal device, which removes excess solvent by making
contact with the solvent of the inks that have been deposited on
the intermediate transfer body 12. The concrete composition of the
solvent removing roller 50 is described in detail hereinafter.
[0052] In the embodiment shown in FIG. 1, one solvent removing
roller 50 is arranged on the firthest downstream side of the
recording heads 22; however, the implementation of the present
invention is not limited to this. For instance, there is also a
mode in which solvent removing rollers 50 are disposed respectively
on the downstream sides of the recording heads 22. This mode is
especially suitable for cases where the amount of solvent of the
inks deposited by the recording heads 22 is high, and it enables
the excess solvent to be collected reliably.
[0053] A transfer unit 26, which transfers the image from the
intermediate transfer body 12 to the recording medium 14, is
disposed on the downstream side of the solvent removing roller 50
in terms of the direction of rotation of the transfer body. A nip
roller 28 is arranged in the transfer unit 26 at a position facing
the third roller 20 across the intermediate transfer body 12, and a
prescribed nip pressure is applied by the nip roller 28 to the
inner surface side of the recording medium 14 (the surface reverse
to the recording surface)
[0054] Next, the action of the inkjet recording apparatus 10 is
described.
[0055] Firstly, the ink droplets are ejected from the recording
heads 22 (22K, 22C, 22M and 22Y) and deposited on the intermediate
transfer body 12, thereby forming an image on the intermediate
transfer body 12. When the image forming region (the region where
the ink droplets have been deposited) on the intermediate transfer
body 12 is moved to the position where the solvent removing roller
50 is disposed, on the downstream side in terms of the direction of
rotation of the transfer body, then the excess solvent of the inks
on the intermediate transfer body 12 is removed by the solvent
removing roller 50. Moreover, when the image forming region on the
intermediate transfer body 12 from which the excess solvent has
been removed is then moved to the transfer unit 26, which is on the
downstream side, then the image is transferred from the
intermediate transfer body 12 to the recording medium 14, while the
prescribed nip pressure is applied by the nip roller 28, to the
inner surface side of the recording medium 14. Thereupon, the
recording medium 14 onto which the image has been transferred is
outputted to the exterior of the inkjet recording apparatus 10.
[0056] Although the configuration with the KCMY four standard
colors is described in the present embodiment, combinations of the
colored inks and the number of colors are not limited to those.
Light colored inks, dark colored inks or special colored inks can
be added as required. For example, a configuration is possible in
which recording heads for ejecting light-colored inks such as light
cyan and light magenta are added.
[0057] Although not shown in the drawings, there is a mode in which
a treatment liquid deposition device, which deposits, onto the
intermediate transfer body 12, a treatment liquid (coloring
material aggregating liquid) containing a component that causes the
coloring materials of the colored inks to aggregate, is disposed on
the upstream side or the downstream side of the recording heads
(ink ejection heads) 22 corresponding to the colored inks. The
treatment liquid deposition device may adopt a mode using a
recording head that ejects the treatment liquid (treatment liquid
head) or a treatment liquid application roller, or the like. It is
possible to provide either only one treatment liquid deposition
device, or to provide a treatment liquid deposition device for each
of the recording heads 22 corresponding to the colored inks.
According to a mode which uses the treatment liquid in this way,
the colored inks and the treatment liquid are deposited onto the
intermediate transfer body 12, and an aggregate of the coloring
materials is generated by the mixing and reacting of the colored
inks and the treatment liquid on the intermediate transfer body 12.
Therefore, it is possible to improve the fixing properties of the
recorded image on the intermediate transfer body 12.
[0058] FIG. 2 is a principal block diagram showing the system
configuration of the inkjet recording apparatus 10 of the present
embodiment. As shown FIG. 2, the inkjet recording apparatus 10
includes a communication interface 30, a system controller 32, an
image memory 34, a motor driver 36, a heater driver 3 8, a pressure
driver 39, a print controller 40, an image buffer memory 42, a head
driver 44, a print determination unit 47, and the like.
[0059] The communication interface 30 is an interface unit for
receiving image data sent from a host computer 46. A serial
interface or a parallel interface may be used as the communication
interface 30. A buffer memory (not shown) may be mounted in this
portion in order to increase the communication speed.
[0060] The image data sent from the host computer 46 is received by
the inkjet recording apparatus 10 through the communication
interface 30, and is temporarily stored in the image memory 34. The
image memory 34 is a storage device for temporarily storing image
data inputted through the communication interface 30, and the data
is written and read to and from the image memory 34 through the
system controller 32. The image memory 34 is not limited to a
memory composed of semiconductor elements, and a hard disk drive or
another magnetic medium may he used.
[0061] The system controller 32 is a control unit which controls
the respective sections, such as the communication interface 30,
the image memory 34, the motor driver 36, the heater driver 38, the
pressure driver 39, and the like. The system controller 32 includes
a central processing unit (CPU) and peripheral circuits thereof
controls communications with the host computer 46 and reading from
and writing to the image memory 34, and the like, and generates
control signals for controlling the motors 48 and heaters 49 in the
conveyance system.
[0062] The motor driver (drive circuit) 36 drives the motor 48 in
accordance with commands from the system controller 32. The heater
driver (drive circuit) 38 drives each heater 49 of the respective
units in accordance with commands from the system controller
32.
[0063] In particular, in the inkjet recording apparatus 10
according to the present embodiment, the system controller 32
includes a pressure control unit 32a, by which the pressure
apparatus 41 is controlled through a pressure driver 39. The
pressure apparatus 41 corresponds to suction devices 74 and 76 (see
FIG. 4) and a device 82 (see FIG. 7), which are described
hereinafter. Furthermore, although not shown in the drawings, in
the case of a mode where a heater 86 (see FIG. 9) is provided in
the solvent absorbing device, which is described hereinafter, the
system controller 32 also controls the heater 86.
[0064] The print controller 40 has a signal processing function for
performing various tasks, compensations, and other types of
processing for generating print control signals from the image data
stored in the image memory 34 in accordance with commands from the
system controller 32 so as to supply the generated print control
signal (dot data) to the head driver 44. Prescribed signal
processing is carried out in the print controller 40, and the
ejection amount and the ejection timing of the ink droplets from
the recording heads 22 are controlled through the head driver 44,
on the basis of the print data. By this means, prescribed dot size
and dot positions can be achieved.
[0065] The print controller 40 is provided with the image buffer
memory 42; and image data, parameters, and other data are
temporarily stored in the image buffer memory 42 when image data is
processed in the print controller 40. The aspect shown in FIG. 2 is
one in which the image buffer memory 42 accompanies the print
controller 40; however, the image memory 34 may also serve as the
image buffer memory 42. Also possible is an aspect in which the
print controller 40 and the system controller 32 are integrated to
form a single processor.
[0066] The head driver 44 generates drive signals for driving the
actuators (e.g., piezoelectric elements) of the recording heads 22
on the basis of the print data supplied by the print controller 40,
and the head driver 44 supplies the drive signals thus generated to
the actuators. The head driver 44 can be provided with a feedback
control system for maintaining constant drive conditions for the
print heads.
[0067] The print determination unit 47 is a block that includes the
line sensor, reads the image printed on the recording head 22,
determines the print conditions (presence of the ejection,
variation in the dot formation, and the like) by performing desired
signal processing, or the like, and provides the determination
results of the print conditions to the print controller 40.
[0068] According to requirements, the print controller 40 makes
various corrections with respect to the recording head 22 on the
basis of information obtained from the print determination unit
47.
[0069] FIGS. 3A and 3B are schematic drawings showing compositions
of the inkjet recording apparatus according to other embodiments of
the present invention. In FIGS. 3A and 3B, the parts common or
similar with those in FIG. 1 are denoted with the same reference
numerals.
[0070] In the inkjet recording apparatus 10A shown in FIG. 3A, an
intermediate transfer body 12A constituted of a drum-shaped member
is used. At least the surface of the intermediate transfer body
(drum-shaped member) 12A is formed of a non-permeable medium. For
example, the intermediate transfer body 12A used is formed by
coating the surface of a metal drum with a layer of a non-permeable
medium (polyimide, polytetrafluoroethylene, or the like).
[0071] Recording heads 22 (22K, 22C, 22M, 22Y) are arranged at
positions facing the surface of the intermediate transfer body 12A,
and a solvent removing roller 50 is arranged on the downstream side
of the recording head 22Y in the direction of rotation of the
transfer body (the counter-clockwise direction in FIG. 3A). The
solvent removing roller 50 is disposed so as to substantially make
contact with the surface of the intermediate transfer body 12A, and
the solvent removing roller removes excess solvent from the
intermediate transfer body 12A.
[0072] Here, the action of the inkjet recording apparatus 10A is
described.
[0073] Firstly, an image is formed on the intermediate transfer
body 12A by ejection of droplets of the inks from the recording
heads 22 (22K, 22C, 22M, 22Y) corresponding to the respective
colored inks. When the image forming region on the intermediate
transfer body 12A (the region where the ink droplets have been
deposited) arrives at the position where the solvent removing
roller 50 is disposed, on the downstream side in the direction of
rotation of the transfer body, due to the rotation of the
intermediate transfer body 12A in the direction of rotation of the
transfer body (the counter-clockwise direction in FIG. 3A), then
the excess solvent on the intermediate transfer body 12A is removed
by the solvent removing roller 50. Moreover, in the transfer unit
26, which is disposed further to the downstream side, the image is
transferred from the intermediate transfer body 1 2A to the
recording medium 14, in a state where a prescribed nip pressure is
applied by the nip roller 28 to the recording medium 14 that has
entered in between the intermediate transfer body 12A and the nip
roller 28. Thereupon, the recording medium 14 onto which the image
has been transferred is outputted to the exterior of the inkjet
recording apparatus 10A.
[0074] The inkjet recording apparatus 10B shown in FIG. 3B is a
direct recording type of recording apparatus, which records
directly onto a recording medium 14B, by performing ink ejection
from the recording heads 22 (22K, 22C, 22M, 22Y) corresponding to
the respective colored inks, onto the recording medium 14B. In the
present embodiment, a non-permeable medium (made of plastic, metal,
glass, or the like), or a recording medium having a slow speed of
permeation (coated paper, or the like), is used as the recording
medium 14B.
[0075] A conveyance belt 12B, which serves as the conveyance device
for the recording medium 14B, is an endless belt wound about the
exterior of three rollers 16B, 18B and 20B. The first roller 16B is
a drive roller, the second roller 18B is an idle roller and the
third roller 20B is a tensioning roller. The third roller
(tensioning roller) 20B is movable in the vertical direction in
FIG. 3B, in order to avoid slack, distortion, or the like, of the
conveyance belt 12B. By this means, since a prescribed tension is
applied to the conveyance belt 12B, then it is possible to convey
the recording medium 14B in a stable state at all times.
[0076] When the recording medium 14B is supplied onto the
conveyance belt 12B by a paper conveyance mechanism (not shown),
then due to the movement (rotation) of the conveyance belt 12B
caused by the rotation of The drive roller 16B, the recording
medium 14B is conveyed successively to positions facing the
respective recording heads 22, the corresponding inks are deposited
onto the recording medium 14B from the respective recording heads
22, and at a further downstream position in the paper conveyance
direction (the left to right direction in FIG. 3B), the excess
solvent on the recording medium 14B is removed by the solvent
removing roller 50. Thereupon, the recording medium 14B is
outputted to the exterior of the inkjet recording apparatus
10B.
[0077] The intermediate transfer bodies 12 and 12A in FIGS. 1 and
3A and the recording medium 14B in FIG. 3B are not limited to being
non-permeable bodies, and for example, if using an ink of low
permeability that has a viscosity of 20 cP or above, then it is
possible to use a permeable body made of porous rubber, or the
like.
[0078] The embodiment shown in FIG. 1 is desirable for the general
paper having a high permeation speed, since the coloring materials
are transferred to the paper after removing the excess solvent, and
deterioration of the image quality due to bleeding of the coloring
materials, wrinkling of the paper, or the like, is avoided. The
embodiment shown in FIG. 3A can be considered to be similar to FIG.
1; however, since the apparatus becomes larger in size and the
related costs are higher, then the composition in FIG. 1 is
preferable.
Solvent Absorbing Device
[0079] Next, the solvent absorbing devices according to embodiments
of the present invention are described with respect to the solvent
absorbing device that has the solvent removing roller 50 used in
the above-described inkjet recording apparatuses in FIGS. 1, 3A and
3B.
First Embodiment
[0080] FIG. 4 is a schematic drawing showing the composition of the
solvent absorbing device according to a first embodiment. In FIG.
4, numeral 50 denotes a solvent removing roller, 52 denotes a
nonpermeable medium, 54 denotes ink and treatment liquid (coloring
material aggregating reaction liquid), 56 denotes coloring material
(colorant), and 58 denotes a solvent. The non-permeable medium 52
corresponds to the intermediate transfer body 12 (in FIG. 1) or 12A
(in FIG. 3A) or the recording medium 14B (see FIG. 3B), which is
used in the above-described inkjet recording apparatus. The
coloring material 56 is formed by pigment particles or dye that has
aggregated and formed particles. FIG. 4 shows a mode where, when
the non-permeable medium 52 having the ink 54 deposited on the
surface thereof is conveyed in the medium conveyance direction (the
direction of an arrow A in FIG. 4), then a portion of the solvent
58 (the excess solvent) on the non-permeable medium 52 is removed
by the solvent removing roller 50.
[0081] As shown in FIG. 4, the solvent removing roller 50 is
composed of a hollow open roller 60 and a cylindrical absorbing
body (porous body) 62. The hollow open roller 60 is constituted of
a cylindrical member, of which the inner side is divided into two
spaces (chambers) 66 and 68 whereby the cross-section in the
direction perpendicular to the axial direction is divided into a
plurality of regions, and in which opening sections 70 and 72 are
formed in the respective spaces 66 and 68 so as to pass from the
outer surface of the cylindrical member to the inner surface
thereof. The cylindrical absorbing body 62 is arranged over the
outer surface of the hollow open roller 60, and is rotatable
relatively with respect to the hollow open roller 60.
[0082] The inner side of the hollow open roller 60 is divided into
the two spaces 66 and 68 by means of a plate-shaped partition 64,
which is parallel to the axial direction of the roller 60 (the
obverse-reverse direction of the sheet containing FIG. 4), and the
first space 66 is a sucking space, which promotes the collection of
the solvent through the absorbing body 62, and the second space 68
is a drying space for drying the absorbing body 62.
[0083] The first opening section 70, which corresponds to the first
space 66, and the second opening section 72, which corresponds to
the second space 68, are formed in the hollow open roller 60. The
first and second spaces 66 and 68 on the inner side of the hollow
open roller 60 respectively connect through the first and second
opening sections 70 and 72 with the absorbing body 62, which is
disposed over the outer side of the hollow open roller 60.
[0084] FIGS. 5A and 5B are external oblique views including partial
cross-sections showing the composition of the solvent removing
roller 50 according to the present embodiment. It is possible that
each of the opening sections 70 and 72, which are formed
respectively in the spaces 66 and 68, is formed as one large
opening 73A as shown in FIG. 5A, or as a plurality of small
openings 73B as shown in FIG. 5B. The shapes of the openings
constituting the opening sections 70 and 72 are not limited in
particular to the examples shown in FIGS. 5A and 5B, and besides
the rectangular shape or the circular shape, it is of course also
possible to adopt an elliptical shape, or other polygonal shapes.
Furthermore, the sizes and shapes of the openings of the opening
sections 70 and 72 do not have to be uniform. For example, it is
also possible to achieve reliable drying by setting a larger
opening surface area in the central portion of the roller, where
the ejection volume, or the amount of solvent, is greater,
relatively to the end portions. The solvent removing roller 50
shown in FIG. 4 depicts the cross-sectional view with respect to
FIG. 5A, for example.
[0085] In implementing the present invention, although there are no
particular restrictions on the opening area of each of the opening
sections 70 and 72 (if each is constituted of a plurality of
openings, the opening area is the total area of the plurality of
openings), it is desirable that each of the opening sections 70 and
72 has as broad as possible the opening area in relation to the
corresponding one of the spaces 66 and 68, from the viewpoint of
raising the efficiency of the collection of the excess solvent
through the absorbing body 62, and the drying of the absorbing body
62. On the other hand, it is also necessary to ensure the rigidity
of the hollow open roller 60. Hence, it is desirable that each of
the opening sections 70 and 72 has an opening area of 40% to 80%,
more desirably 50% to 70%, with respect to the surface area of the
inner surface (before the opening sections 70 and 72 are formed)
that makes contact with the corresponding one of the spaces 66 and
68 of the cylindrical member forming the base of the hollow open
roller 60.
[0086] As shown in FIG. 4, the solvent removing roller 50 is
disposed so as to be substantially in contact with the surface of
the non-permeable medium 52. More specifically, the solvent
removing roller 50 is disposed in such a manner that at least a
portion of the surface of the absorbing body 62, which rotates over
the outer side of the hollow open roller 60, makes contact with the
solvent 58 of the ink 54 that has been deposited on the
non-permeable medium 52. In this case, from the viewpoint of
preventing degradation of the image, it is desirable that the
solvent removing roller 50 is disposed in such a manner that a
slight gap is formed between the surface of the absorbing body 62
and the non-permeable medium 52, in such a manner that the surface
of the absorbing body 62 does not make contact with the coloring
material 56 on the non-permeable medium 52. When the surface of the
absorbing body 62 makes contact with the solvent 58, the solvent 58
is absorbed into the absorbing body 62 by the capillary action in
the absorbing body 62.
[0087] The opening sections 70 and 72, which are formed in the
hollow open roller 60, are disposed at the positions that do not
face the solvent contacting surface of the absorbing body 62. The
reason for this is that if the opening sections 70 and 72 were
disposed at the positions facing the solvent contacting surface of
the absorbing body 62, then due to the effects of the negative
pressure applied to the spaces 66 and 68, as described hereinafter,
the coloring material 56 would adhere to the surface of the
absorbing body 62, giving rise to degradation of the image.
[0088] The first opening section 70 and the second opening section
72 are arranged successively on the downstream side in the
direction of rotation of the absorbing body 62 (the direction of
arrow B in FIG. 4), from the solvent contacting surface of the
absorbing body 62. In other words, the first opening section 70 is
disposed on the upstream side of the second opening section 72, in
terms of the direction of rotation of the absorbing body 62.
[0089] Lets of the suction devices 74 and 76 are connected
respectively to the spaces 66 and 68, and outlets of the suction
devices 74 and 76 are connected to a common liquid collection
container 78. The liquid collection container 78 is an unsealed
container having an air connection hole 78a formed in a portion
thereof. Prescribed negative pressures (suction pressures) are
applied to the spaces 66 and 68 by the suction devices 74 and 76.
The negative pressures applied to the spaces 66 and 68 may be same
or they may be different.
[0090] Due to the negative pressure applied to the first space 66,
the negative pressure is transmitted to the peripheral area of the
solvent contacting surface of the absorbing body 62 through the
first opening section 70, and therefore the collection of the
excess solvent through the absorbing body 62 can be promoted.
Consequently, the first opening section 70 is desirably positioned
in the vicinity of the solvent contacting surface of the absorbing
body 62, to the downstream side thereof in terms of the direction
of rotation of the absorbing body 62. For example, it is desirable
that the lower end (the end on the side of the non-permeable medium
52) of the first opening section 70 is disposed at a position that
is distanced at least 5 mm from the liquid surface of the solvent
58 on the non-permeable medium 52.
[0091] It is necessary that the negative pressure applied to the
first space 66 is set to a suitable range. If the absolute value of
the negative pressure applied to the first space 66 is too great
(i.e., the pressure applied to the first space 66 is excessively
less than the atmospheric pressure), then the negative pressure is
transmitted to the non-permeable medium 52 through the first
opening section 70 and the gap inside the absorbing body 62, and
therefore it is possible that image degradation may occur due to
the adherence of the coloring material 56 to the surface of the
absorbing body 62. On the other hand, if the absolute value of the
negative pressure applied to the first space 66 is too little
(i.e., the pressure applied to the first space 66 is not enough
less than the atmospheric pressure), then it is not possible
sufficiently to collect the excess solvent from the non-permeable
medium 52. Consequently, it is desirable that the negative pressure
applied to the first space 66 is set to the appropriate range
whereby the aforementioned problems can be prevented. Hereinafter,
the expression "the negative pressure is great" means that the
absolute value of the negative pressure is great and the pressure
is relatively much less than the atmospheric pressure, and the
expression "the negative pressure is little" means that the
absolute value of the negative pressure is little and the pressure
is not much less than the atmospheric pressure.
[0092] Due to the negative pressure applied to the second space 68,
it is possible to dry the absorbing body 62 through the second
opening section 72. When a great negative pressure is applied to
the second space 68, since the interior of the absorbing body 62
that corresponds to the second space 68 does not fill with the
solvent, then the negative pressure is not transmitted through the
interior of the absorbing body 62 and air flows into the solvent
removing roller 50 from outside. Consequently, it is possible to
set the negative pressure applied to the second space 68 greater
than the negative pressure applied to the first space 66, and it is
thus possible to improve the drying capacity in relation to the
absorbing body 62.
[0093] The negative pressures applied to the spaces 66 and 68 can
be controlled by means of the suction forces of the suction devices
74 and 76, which are connected respectively to the spaces 66 and
68. The suction forces of the suction devices 74 and 76 can be
controlled by changing the flow rates in the suction devices 74 and
76, for example.
[0094] For example, if the print rate (the print volume per unit
surface area) is high and the amount of the excess solvent on the
non-permeable medium 52 is large, then it is desirable to
strengthen the suction forces of the suction devices 74 and 76,
whereby the collection of the excess solvent through the absorbing
body 62, and the drying of the absorbing body 62 can be further
promoted. More specifically, the flow rates in the suction devices
74 and 76 are controlled in proportion with the print rate, as
calculated from the image data.
[0095] Next, the operation start and halt timings of the suction
devices 74 and 76 according to the present embodiment are
described.
[0096] The operation start timing of the first suction device 74 is
set between the start of the ink ejection by the recording heads 22
and the time at which the solvent 58 on the non-permeable medium 52
arrives at the absorbing body 62. Desirably, the amount of movement
of the non-permeable medium 52 is measured by an encoder (not
shown) or the like, and the operation of the first suction device
74 is started when the non-permeable medium 52 is at a position
some 10 mm to 50 mm less than the distance of movement from the
recording heads 22 to the absorbing body 62. Furthermore, the
operation halt timing of the first suction device 74 is set to a
time when the ink ejection by the recording heads 22 has ended and
the solvent 58 is no longer present in the portion where the
absorbing body 62 and the non-permeable medium 52 make contact.
Desirably, the amount of movement of the non-permeable medium 52
from the end of the ink ejection by the recording heads 22 is
measured by the encoder (not shown), and the operation of the first
suction device 74 is halted when the non-permeable medium 52 is at
a position some 10 mm to 50 mm greater than the distance of the
movement from the recording heads 22 to the absorbing body 62.
[0097] On the other hand, the operation start timing of the second
suction device 76 is set to the same timing as the operation start
timing of the first suction device 74, and the operation halt
timing of the second suction device 76 is set to the timing at
which the non-permeable medium 52 halts.
[0098] Next, the action of the solvent absorbing device is
described.
[0099] When a portion of the solvent 58 (the excess solvent) of the
ink 54, that has been deposited on the non-permeable medium 52
makes contact with the absorbing body 62, which constitutes the
surface of the solvent removing roller 50, then the excess solvent
is absorbed into the absorbing body 62 due to the capillary action
in the absorbing body 62. After absorbing the excess solvent, the
portion of the absorbing body 62 containing the excess solvent
moves to the position facing the first opening section 70, with the
rotation of the absorbing body 62 in the direction of rotation of
the absorbing body. In this case, since the negative pressure is
applied on the first space 66 by the first suction device 74, then
the excess solvent that has been absorbed in the absorbing body 62
is collected into the first space 66 through the first opening
section 70, and is then collected into the collection container 78
through the suction device 74. After collecting the excess solvent,
the portion of the absorbing body 62 containing the excess solvent
moves to the position facing the second opening section 72, with
the rotation of the absorbing body 62 in the direction of rotation
of the absorbing body. Since the negative pressure is applied to
the second space 68, the absorbing body 62 is dried through the
second opening section 72. Subsequently, with the rotation of the
absorbing body 62, the collection of the excess solvent by the
absorbing body 62 and the drying of the absorbing body 62 are
repeated alternately.
[0100] According to the present embodiment, since the prescribed
negative pressures are applied respectively to the spaces 66 and
68, then it is possible to collect the excess solvent by means of
the absorbing body 62 through the first opening section 70, and to
dry the absorbing body 62 through the second opening section 72.
Consequently, since the solvent collection and the drying are
repeated alternately in the absorbing body 62 configured to be
rotatable relatively with respect to the open hollow roller 60,
then there is no decline in the absorptive properties of the
absorbing body 62, and the collection of the excess solvent can be
carried out continuously and reliably, while maintaining desired
absorption performance.
[0101] In particular, in the present embodiment, since the suction
devices 74 and 76 are connected respectively to the spaces 66 and
68, then by controlling the suction forces (for example, the flow
rates) of the respective suction devices 74 and 76, it is possible
to control independently the negative pressures applied to the
spaces 66 and 68, and therefore the pressures can be optimized in
accordance with the shapes of the first and second spaces 66 and
68, the first and second opening sections 70 and 72, and the shape
and material of the absorbing body 62, and the like.
Second Embodiment
[0102] Next, a solvent absorbing device according to the second
embodiment of the present invention is described. Below, the parts
common with the first embodiment described above are not explained
further, and the following description centers on the
characteristic features of the second embodiment.
[0103] FIG. 6 is a schematic drawing showing the composition of the
solvent absorbing device according to the second embodiment. In
FIG. 6, the parts common or similar with those in FIG. 4 are
denoted with the same reference numerals.
[0104] The solvent absorbing device shown in FIG. 6 has a check
valve 80 arranged in the partition 64, which divides the interior
of the hollow open roller 60 into the first and second spaces 66
and 68, and the suction device 74 is connected only to the first
space 66. The check valve 80 is configured to be openable and
closeable in accordance with the pressure difference between the
first and second spaces 66 and 68, and when the check valve 80 is
in the closed state, the first and second spaces 66 and 68 are not
connected together, and when the check valve 80 is in the opened
state, the first and second spaces 66 and 68 are connected
together.
[0105] If the suction force of the suction device 74 is low and the
negative pressure applied to the first space 66 is little, then the
check valve 80 is in the closed state, and therefore the first and
second spaces 66 and 68 are not connected and the absorption of the
excess solvent by the absorbing body 62 is promoted through the
first opening section 70.
[0106] On the other hand, if the suction force of the suction
device 74 is high and the negative pressure applied to the first
space 66 is great, then the check valve 80 is opened, and therefore
the first and second spaces 66 and 68 are connected together.
Consequently, the negative pressure in the first space 66 becomes
less, the solvent absorbing force of the absorbing body 62 through
the first opening section 70 is weakened, and the pressure in the
second space 68 falls. Therefore, the absorbing body 62 is dried
through the second opening section 72.
[0107] Similarly to the first embodiment, the operation start
timing of the suction device 74 is set between the start of the ink
ejection by the recording heads 22 and the time at which the
solvent 58 on the non-permeable medium 52 arrives at the absorbing
body 62. Desirably, the amount of movement of the non-permeable
medium 52 is measured by an encoder (not shown) or the like, and
the operation of the suction device 74 is started when the
non-permeable medium 52 is at the position some 10 mm to 50 mm less
than the distance of movement from the recording heads 22 to the
absorbing body 62. Furthermore, the operational halt timing of the
suction device 74 is simultaneous with the timing at which the
non-permeable medium 52 halts.
[0108] According to the present embodiment, it is possible to
promote the collection of the excess solvent by the absorbing body
62, as well as drying the absorbing body 62, simply by controlling
the suction force of the suction device 74 connected to the first
space 66, and therefore it is possible to achieve cost reductions
as well as reducing the size of the apparatus (space savings). In
particular, even in cases where there is a sudden change in the
suction force of the suction device 74, it is still possible to
maintain a uniform pressure in the first space 66 by means of the
check valve 80, and therefore it is possible to prevent adherence
of the coloring material 56 to the surface of the absorbing body
62.
Third Embodiment
[0109] Next, a solvent absorbing device according to the third
embodiment of the present invention is described. Below, the parts
common with the above-described embodiments are not explained
further, and the following description centers on the
characteristic features of the third embodiment.
[0110] FIG. 7 is a schematic drawing showing the composition of the
solvent absorbing device according to the third embodiment. In FIG.
7, the parts common or similar with those in FIG. 4 are denoted
with the same reference numerals.
[0111] In the solvent absorbing device shown in FIG. 7, the suction
device 74 is connected to the first space 66 and a pressurization
device 82 is connected to the second space 68. Since the negative
pressure is applied to the first space 66 by the suction device 74,
then it is possible to promote the collection of the excess solvent
by the absorbing body 62 through the first opening section 70. On
the other hand, since a positive pressure (i.e., a pressure higher
than the atmospheric pressure) is applied to the second space 68 by
the pressurization device 82, then it is possible to apply air flow
to the absorbing body 62 through the second opening section 72 due
to the air supplied to the second space 68, so as to blow away the
solvent and foreign material inside the absorbing body 62 toward
the outer side. Thus, it is possible to dry the absorbing body 62
while also preventing blockages. The operation start and halt
timings of the suction device 74 are the same as in the first
embodiment, and the operation start and halt timings of the
pressurization device 82 are the same as the operation start and
halt timings of the second suction device 76 in FIG. 4.
[0112] FIG. 8 is a schematic drawing showing another composition of
the solvent absorbing device according to the third embodiment. In
FIG. 8, the parts common or similar with those in FIG. 7 are
denoted with the same reference numerals.
[0113] In the solvent absorbing device shown in FIG. 8, the liquid
collection container 78 is a sealed container having a hermetically
sealed interior, and the liquid collection container 78 and the
second space 68 are connected directly, without passing through
another device (suction device or pressurization device).
Therefore, the negative pressure is applied to the suction space 66
by the suction device 74, and the positive pressure is applied to
the drying space 68 through the liquid collection container (sealed
container) 78. The operation start and halt timings of the suction
device 74 are the same as those of the solvent absorbing device
shown in FIG. 6.
[0114] According to the present embodiment, by applying the
negative pressure to the first space 66 while applying the positive
pressure to the second space 68, it is possible to promote the
collection of the excess solvent by the absorbing body 62 and to
dry the absorbing body 62 through the first and second opening
sections 70 and 72.
[0115] In particular, the solvent absorbing device shown in FIG. 8
can be achieved by using the single suction device 74, and
therefore it is possible to achieve cost reduction and size
reduction (space saving).
Fourth Embodiment
[0116] Next, a solvent absorbing device according to the fourth
embodiment of the present invention is described. Below, the parts
common with the above-described embodiments are not explained
further, and the following description centers on the
characteristic features of the fourth embodiment.
[0117] FIG. 9 is a schematic drawing showing the composition of the
solvent absorbing device according to the fourth embodiment. In
FIG. 9, the parts common or similar with those in FIG. 8 are
denoted with the same reference numerals.
[0118] The solvent absorbing device shown in FIG. 9 includes a
heating device 86, which is arranged between the liquid collection
container (sealed container) 78 and the second space 68. Since the
air that has been heated by the heating device 86 is supplied to
the second space 68, then it is possible to apply the flow of
heated air to the absorbing body 62 through the second opening
section 72 so as to promote the evaporation of the solvent inside
the absorbing body 62. Furthermore, since the heated air can make
the viscosity of the solvent inside the absorbing body 62 lowered,
then it is possible readily to blow away the solvent toward the
outside of the absorbing body 62, and therefore the drying of the
absorbing body 62 can be promoted.
[0119] The heating device 86 is controlled so as to start heating
at the timing that the positive pressure is applied to the second
space 68, and to halt heating at the timing that the application of
the positive pressure is halted. Moreover, it is desirable that the
heating temperature of the heating device 86 is controlled in such
a manner that the temperature of the air supplied to the second
space 68 is within a range of 40.degree. C. to 80.degree. C. If the
absorbing body 62 has poor thermal resistance or the solvent 58 is
liable to react with heat, then a desirable mode is one where a
temperature sensor is arranged in the second space 68, for
instance, and the heating device 86 is controlled on the basis of
the temperature measured with this temperature sensor, so as to set
the air that is supplied to the second space 68 to an optimum
temperature. The operation start and halt timings of the suction
device 74 are the same as those of the second embodiment.
[0120] FIG. 10 is a schematic drawing showing another composition
of the solvent absorbing device according to the fourth embodiment.
In FIG. 10, the parts common or similar with those in FIG. 9 are
denoted with the same reference numerals.
[0121] In the solvent absorbing device shown in FIG. 10, the
heating device 86 is arranged in the second space 68. In this case,
compared to the solvent absorbing device shown in FIG. 9, the air
in the second space 68 can be controlled more readily to an optimum
temperature and the heating efficiency is improved.
[0122] FIG. 11 is a schematic drawing showing yet another
composition of the solvent absorbing device according to the fourth
embodiment. In FIG. 11, the parts common or similar with those in
FIG. 9 are denoted with the same reference numerals.
[0123] In the solvent absorbing device shown in FIG. 11, the
heating device 86 is arranged in the second space 68, and the
pressurization device 82 is connected to the second space 68.
Moreover, the liquid collection container 78 is the non-sealed
container, which has the air connection hole 78a. The positive
pressure is applied to the second space 68 by the pressurization
device 82, and the air thereby supplied to the second space 68 is
heated by the heating device 86.
[0124] According to the present embodiment, as well as obtaining
similar beneficial effects to those of the third embodiment, it is
also possible to promote the evaporation of the solvent inside the
absorbing body 62 through the second opening section 72, by means
of the heating device 86, and furthermore, since the viscosity of
the solvent inside the absorbing body 62 can be lowered, then the
solvent can be blown out more readily to the outer side of the
absorbing body 62. Thus, the drying of the absorbing body 62 can be
promoted more readily.
Fifth Embodiment
[0125] Next, a solvent absorbing device according to the fifth
embodiment of the present invention is described. Below, the parts
common with the above-described embodiments are not explained
further, and the following description centers on the
characteristic features of the fifth embodiment.
[0126] FIG. 12 is a schematic drawing showing the composition of
the solvent absorbing device according to the fifth embodiment. In
FIG. 12, the parts common or similar with those in FIG. 4 are
denoted with the same reference numerals.
[0127] The solvent absorbing device shown in FIG. 12 is provided
with the solvent removing roller 50 constituted of the hollow open
roller 60 in which the inner side of the cylindrical member is
divided into three spaces, the first and second spaces 66 and 68
and a third space 90, and in which three opening sections, the
first and second spaces 70 and 72 and a third opening section 92,
are respectively formed in the first, second and third spaces 66,
68 and 90 so as to pass from the outer surface of the cylindrical
member to the inner surface thereof. The cylindrical absorbing body
(porous body) 62 is arranged over the outer surface of the hollow
open roller 60, and is rotatable relatively with respect to the
hollow open roller 60. Three suction devices, the first and second
suction devices 74 and 76 and a third suction device 94, are
connected respectively to the first, second and third spaces 66, 68
and 90. The suction devices 74, 76 and 94 are connected to the same
liquid collection container (non-sealed container) 78.
[0128] The first opening section 70 corresponding to the first
space 66, the third opening section 92 corresponding to the third
space 90, and the opening section 72 corresponding to the second
space 68, are disposed in sequence toward the downstream side from
the solvent contacting surface of the absorbing body 62, following
the direction of rotation of the absorbing body 62. In other words,
the third opening section 92 is disposed to the downstream side of
the opening section 70, in terms of the direction of rotation of
the absorbing body 62, and to the upstream side of the second
opening section 72 in terms of the direction of rotation of the
absorbing body 62.
[0129] A liquid deposition device 96 is provided at a position
opposite to the third opening section 92 through the absorbing body
62. The liquid deposition device 96 deposits a prescribed liquid
(for example, water or cleaning liquid) onto the surface of the
absorbing body 62 placed over the third opening section 92. There
are no particular restrictions on the liquid deposition method used
by the liquid deposition device 96, and it is possible to use
various methods, such as spraying, dripping, spreading, or the
like.
[0130] Due to the negative pressure applied to the absorbing body
62 by the third suction device 94 through the third space 90 and
the third opening section 92, the liquid deposited on the surface
of the absorbing body 62 by the liquid deposition device 96 is
absorbed efficiently in a short period of time into the absorbing
body 62, and the excess solvent of the ink having been absorbed in
the absorbing body 62 and the liquid deposited by the liquid
deposition device 96 on the absorbing body 62 are collected into
the third space 90 though the third opening section 92.
Consequently, the viscosity of the solvent having been absorbed in
the absorbing body 62 is lowered, and the absorbing body 62 is
dried on the downstream side in terms of the direction of rotation
of the absorbing body. Furthermore, if a cleaning liquid is
deposited on the absorbing body 62 by the liquid deposition device
96, then foreign material adhering to the absorbing body 62 can be
collected and blockages can be prevented. In general, the solvent
of the ink includes a high-boiling-point solvent such as glycerin.
The high-boiling-point solvent has a high viscosity compared to
water and if the high-boiling-point solvent contained in the
absorbing body 62 dries directly in the absorbing body 62 then the
viscosity rises further and there is a risk that blockages may
occur. On the other hand, by depositing the liquid on the surface
of the absorbing body 62 by means of the liquid deposition device
96, while applying the negative pressure to the third space 90 by
means of the third suction device 94 as described above, it is
possible to reduce the amount of high-boiling-point solvent
remaining in the absorbing body 62 by lowering the viscosity of the
solvent in the absorbing body 62 while it is collected, and
therefore the prescribed absorptive properties of the absorbing
body 62 can be maintained.
[0131] Next, the operation start and halt timings of the third
suction device 94 according to the present embodiment are
described.
[0132] With regard to the operation start timing of the third
suction device 94, for example, soil of the absorbing body 62 is
determined by using a detector (not shown) such as a reflective
optical sensor, or the like, and when the soil has become heavier
than a prescribed threshold, the operation of the third suction
device 94 is started and the liquid is deposited by the liquid
deposition device 96. With regard to the operation halt timing of
the third suction device 94, the soil is determined by the detector
at regular sampling timings, and the operation of the third suction
device 94 is halted when the soil has not exceeded the prescribed
threshold for a number of determination operations corresponding to
one revolution of the absorbing body 62. For example, it is
desirable that the sampling timing interval is set to 1/10 to 1/2
of the period taken for the absorbing body 62 to perform one
revolution.
[0133] Moreover, as a further example, the amount of solvent or the
recording time is calculated from the image data, the total solvent
volume or recording time is determined accordingly, and when this
total becomes greater than a prescribed threshold, then the
operation of the third suction device 94 is started and the liquid
is deposited by the liquid deposition device 96. As regards the
timing at which the operation of the third suction device 94 is
halted, this timing is set either to the time at which the
non-permeable medium 52 is halted, or after the liquid deposition
has been performed for a prescribed time period. At the halt
timing, the total of the solvent volume or the recording time is
reset and when the liquid deposition is next performed, the
calculation process is repeated again.
[0134] The operation start and halt timings of the first and second
suction devices 74 and 76 are the same as those of the solvent
suction device shown in FIG. 4, and therefore detailed description
thereof is omitted here.
[0135] According to the present embodiment, since the viscosity of
the solvent inside the absorbing body 62 is lowered by the liquid
deposited by the liquid deposition device 96, while the excess
solvent is collected by the absorbing body 62 and subsequent drying
of the absorbing body 62 is carried out, then it is possible to
reduce the amount of high-boiling-point solvent remaining in the
absorbing body 62. Consequently, since the solvent collection, the
lowering of the solvent viscosity and the drying are repeated
successively in the absorbing body 62 rotatable relatively with
respect to the open hollow roller 60, then there is no decline in
the absorptive properties of the absorbing body 62, and the
collection of the excess solvent can be carried out continuously
and reliably, while maintaining desired absorption performance.
Sixth Embodiment
[0136] Next, a solvent absorbing device according to the sixth
embodiment of the present invention is described. Below, the parts
common with the above-described embodiments are not explained
further, and the following description centers on the
characteristic features of the sixth embodiment.
[0137] FIG. 13 is a schematic drawing showing the composition of
the solvent absorbing device according to the sixth embodiment. In
FIG. 13, the parts common or similar with those in FIG. 4 are
denoted with the same reference numerals.
[0138] The solvent absorbing device shown in FIG. 13 has a
cylindrical liquid storage section 98 formed in the central portion
of the inner side of the hollow open roller 60. The inlets of the
first and second suction devices 74 and 76 are respectively
connected to the first and second spaces 66 and 68, and the outlets
of the first and second suction devices 74 and 76 are connected to
the liquid storage section 98.
[0139] The excess solvent collected by the suction devices 74 and
76 is accumulated in the liquid storage section 98. When the
absorbing body 62 is replaced with a new one, due to deterioration,
it is possible simultaneously to discard the excess solvent
accumulated in the liquid storage section 98, and therefore the
associated maintenance tasks can be simplified. Furthermore, since
there is no need to provide a separate liquid collection container,
it is also possible to save space.
[0140] The operation start and halt timings of the suction devices
74 and 76 are the same as those of the solvent absorbing device
shown in FIG. 4.
[0141] As described above, according to the solvent absorbing
device of the present invention, it is possible to promote the
collection of the excess solvent by means of the absorbing body 62
through the first opening section 70, due to the negative pressure
applied to the first space 66, and it is also possible to carry out
drying of the absorbing body 62 through the second opening section
72, due to the prescribed pressure (negative pressure or positive
pressure) applied to the second space 68, to the downstream side in
the direction of rotation of the absorbing body 62. In other words,
in the absorbing body 62 rotating over the outer side of the hollow
open roller 60, the solvent collection and the drying are repeated
alternately, and consequently there is no decline in the absorptive
properties of the absorbing body 62 and it is possible to collect
the excess solvent continuously in a reliable manner, while
maintaining a prescribed absorption performance.
[0142] In the above-described embodiments, the interior of the
hollow open roller 60 is divided into two or three spaces, but in
implementing the present invention, it may be divided into four or
more spaces. For example, a mode is possible in which each of the
first and second spaces 66 and 68 is divided into a plurality of
spaces (small chambers), and a prescribed pressure is applied to
each of these small chambers independently. According to this mode,
it is possible to optimize the solvent collection and the drying,
in accordance with the size of the recorded image.
[0143] It should be understood, however, that there is no intention
to limit the invention to the specific forms disclosed, but on the
contrary, the invention is to cover all modifications, alternate
constructions and equivalents falling within the spirit and scope
of the invention as expressed in the appended claims.
* * * * *