Liquid ejection apparatus, cleaning apparatus for liquid ejection head, and inkjet recording apparatus

A liquid ejection apparatus includes: a liquid ejection head; a long wiping member configured to come in contact with and wipe a liquid ejection face of the head; a wiping member conveyance device configured to drive the wiping member to be conveyed in a lengthwise direction of the wiping member; a pressing member configured to cause the wiping member to come in contact and pressed against the liquid ejection face when the pressing member is placed at a first position; and a slack elimination mechanism configured to push down the pressing member to a second position lower than the first position before the wiping member is brought into contact with the liquid ejection face, and to stop pushing the pressing member so as to move the pressing member along with the wiping member to the first position to bring the wiping member into contact with the liquid ejection face.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a liquid ejection apparatus, a cleaning apparatus for a liquid ejection head, and an inkjet recording apparatus, and more particularly to head cleaning technology for wiping a liquid ejection face of a liquid ejection head by means of a long wiping member, and to a liquid ejection apparatus and an inkjet recording apparatus using this technology.

2. Description of the Related Art

In an inkjet recording apparatus, with use, foreign material such as ink residue or paper dust adheres to a liquid ejection face (a nozzle face formed with nozzles) of a liquid ejection head. When the foreign material adheres to the nozzles and/or the periphery thereof, the adhering material affects ink droplets ejected from the nozzles and causes deviation in the ejection direction of the ink droplets, and it is then difficult to deposit the ink droplets at prescribed positions on the recording medium. As a result of this, the output image quality declines. Therefore, in an inkjet recording apparatus, a maintenance operation is carried out to remove foreign material adhering to the nozzle face, periodically or at a suitable timing (see, for example, Japanese Patent Application Publication Nos. 2005-022251 and 2007-030482).

Japanese Patent Application Publication No. 2005-022251 discloses a wiping unit including: a cleaning liquid supply device, which supplies cleaning liquid to a long wiping sheet (wiping member) wound in the form of a roll; and a pressing device, which presses the wiping sheet against the nozzle face of the liquid ejection head. The wiping sheet is paid out from a pay-out reel of a sheet supply unit, and is taken up onto a take-up reel through a pressing roller. By moving the pressing roller over the nozzle face while thus conveying the wiping sheet in a prescribed direction, the wiping sheet is pressed against the nozzle face and caused to rub the nozzle face, thereby wiping the nozzle face. Moreover, Japanese Patent Application Publication No. 2005-022251 proposes to provide the wiping unit with a controller configured to cause a first wiping operation of pressing the wiping sheet impregnated with the cleaning liquid against the nozzle face, and to then cause a second wiping operation of pressing a wiping sheet in a dry state against the nozzle face.

Japanese Patent Application Publication No. 2007-030482 discloses a cleaning apparatus for an inkjet head including: a supporting device, which supports a flexible cleaning device in the form of a sheet, such as a cloth or film, at a position under a lower face of a head; and a pressing device, which presses the cleaning device supported by the supporting device to the lower face of the head from below.

In Japanese Patent Application Publication No. 2005-022251, the pressing roller for pressing the wiping sheet against the nozzle face is constituted of an elastic roller formed by attaching an elastic body of rubber, or the like, to the outer circumference of a shaft (paragraph 0056 in Japanese Patent Application Publication No. 2005-022251). When the elastic roller (pressing roller) moves transversely in the region under the nozzle face, the wiping sheet and the pressing roller are compressed in the downward direction, in such a manner that the wiping sheet is pressed against the nozzle face due to an elastic restoring force of the pressing roller. However, the apparatus according to Japanese Patent Application Publication No. 2005-022251 does not include any device to manage the pressing force.

On the other hand, in Japanese Patent Application Publication No. 2007-030482, the pressing force applied to the head is adjusted by deformation of the pressing device, which deforms elastically upon the pressing action.

However, due to the deformation of the elastic member, the sheet-formed flexible cleaning device (the wiping member such as cloth or film) is distorted, and it becomes impossible to convey the cleaning device. When it becomes impossible to convey the cleaning device due to the occurrence of distortion, the wiping surface of the sheet-shaped cleaning device is not renewed, then the wiping surface having been soiled is used to wipe the head, and hence there is a problem in that the soiling becomes attached again to the nozzle face.

This issue in the related art is described here by a concrete example shown inFIGS. 13 and 14.FIGS. 13 and 14show a liquid ejection head (hereinafter referred to as the “head”)520and a wiping unit630, which wipes a nozzle face522of the head520. The wiping unit630includes: a pay-out side web core634, which supplies a long wiping web632; a take-up side web core636, which takes up the wiping web632that has been paid out; a pressing roller640, which presses the wiping web632against the nozzle face522of the head520; an impelling spring642, which impels the pressing roller640and the wiping web632wrapped thereon in the upward direction inFIGS. 13 and 14; and a pair of web driving rollers650, which drives the wiping web632to be conveyed.

The wiping web632that has been paid out from the pay-out side web core634is wound up onto the take-up side web core636through a first guide roller672, a second guide roller676and the pressing roller640. A cleaning liquid deposition roller662is disposed between the first guide roller672and the second guide roller676, and is configured to deposit the cleaning liquid on the wiping web632.

In the composition shown inFIG. 13, a relative movement of the head520and the wiping unit630is carried out. Here, an example is described where the head520is horizontally moved from the left-hand side toward the right-hand side in the direction indicated with an arrow A inFIG. 13, but it is also possible to adopt a composition where the head520is stationary and the wiping unit630is moved from the right-hand side toward the left-hand side in the drawing.

As shown inFIG. 13, in a state before the wiping web632comes in contact with the nozzle face522of the head520, the wiping unit630is arranged in such a manner that the uppermost position638of the wiping web632wrapped around the pressing roller640is slightly (for example, by approximately 1.5 mm) higher than the position of the nozzle face522. When wiping the nozzle face522, the impelling spring642is compressed in accordance with the height differential (the amount of overlap) between the nozzle face522and the uppermost position638of the wiping web632, and the wiping web632is pressed against the nozzle face522.

When the wiping web612thereby comes in contact with the nozzle face522while the impelling spring622is compressed, then as shown inFIG. 14, slacks702of the wiping web632occur on both of the upstream side and the downstream side of the pressing roller640. For example, if there is the overlap of approximately 1.5 mm, then when the wiping web632comes in contact and pressed against the nozzle face522, the slack702of 1.5 mm occurs in the wiping web632on each side of the pressing roller640, i.e., the slacks702in total of approximately 3 mm occur on both the sides. In this case, when the web drive roller650drives the wiping web632at the conveyance speed of 3.2 mm/s, then a state arises in which the wiping web632cannot be conveyed for approximately one second between the occurrence and disappearance of the slacks702. During this time, the nozzle face522is wiped with a soiled surface of the wiping web632.

An issue of this kind is not limited to the inkjet printer, but rather is also a common problem in liquid ejection apparatuses of various kinds which use liquid ejection heads.

SUMMARY OF THE INVENTION

The present invention has been contrived in view of these circumstances, an object thereof being to provide a liquid ejection apparatus, a cleaning apparatus for a liquid ejection head, and an inkjet recording apparatus, in which head cleaning properties can be improved by suppressing slack of a long wiping member when the long wiping member comes in contact and pressed against a liquid ejection face of a liquid ejection head and caused to wipe the liquid ejection face.

In order to attain the aforementioned object, the present invention is directed to a liquid ejection apparatus, comprising: a liquid ejection head which has a liquid ejection face formed with nozzles configured to eject droplets of liquid; a long wiping member which is configured to come in contact with the liquid ejection face to wipe the liquid ejection face; a wiping member conveyance device which is configured to drive the wiping member to be conveyed in a forward conveyance direction in a lengthwise direction of the wiping member; a pressing member which is configured to cause the wiping member to come in contact and pressed against the liquid ejection face when the pressing member is placed at a first position; an elastic member which is configured to elastically deform and apply a force to cause the wiping member to be pressed against the liquid ejection face through the pressing member when the wiping member comes in contact and pressed against the liquid ejection face; a relative movement device which is configured to cause relative movement of the liquid ejection head with respect to the wiping member that is in contact with the liquid ejection head and travels by being driven to be conveyed by the wiping member conveyance device; and a slack elimination mechanism which is configured to push down the pressing member against the force of the elastic member to a second position lower than the first position before the wiping member is brought into contact with the liquid ejection face, and is configured to stop pushing the pressing member having been pushed down to the second position so as to move the pressing member along with the wiping member to the first position to bring the wiping member into contact with the liquid ejection face.

According to this aspect of the invention, an occurrence of slack of the wiping member when the wiping member comes in contact with the liquid ejection face of the liquid ejection head can be prevented. Accordingly, the wiping member can come in contact and pressed against the liquid ejection face in a slack-free state (including a state where an amount of slack is suppressed to a level at which such slack does not pose a problem). Consequently, it is possible to wipe the liquid ejection face always with a new wiping surface by successively conveying the wiping member, and hence the wiping properties can be improved.

Preferably, the slack elimination mechanism includes a tensioning mechanism which is configured to restrain travel of the wiping member in the forward conveyance direction at an upstream side of the pressing member in the forward conveyance direction, to tension the wiping member in cooperation with the wiping member conveyance device, and is configured to push down the pressing member along with the wiping member to the second position by tensioning the wiping member.

According to this aspect of the invention, by tensioning the wiping member that is in contact with the pressing member, the pressing member can be pushed down together with the wiping member.

Preferably, the tensioning mechanism includes: a nip member which is arranged on the upstream side of the pressing member in the forward conveyance direction of the wiping member, the nip member being movable to a nip position where the nip member nips the wiping member to suppress a conveyance movement of the wiping member, and to a nip release position where the nip member releases the wiping member; a nip member drive mechanism which is configured to move the nip member to the nip position and the nip release position; and a control device which is configured to control the wiping member conveyance device and the nip member drive mechanism, wherein before the wiping member is brought into contact with the liquid ejection face, the control device controls the wiping member conveyance device to drive the wiping member to be conveyed while controls the nip member drive mechanism to nip the wiping member by the nip member so as to tension the wiping member and thereby push down the pressing member to the second position, and when the wiping member is brought into contact with the liquid ejection face, the control device controls the nip member drive mechanism to move the nip member to the nip release position to release the wiping member.

According to this aspect of the invention, the configuration can be adopted in which the wiping member is fixed by the nip member as the device for suppressing the conveyance movement of the wiping member on the upstream side of the pressing member in the forward conveyance direction of the wiping member.

It is also preferable that the tensioning mechanism includes: a reverse conveyance driving device which is configured to apply a traveling force to the wiping member in a reverse conveyance direction reverse to the forward conveyance direction at the upstream side of the pressing member in the forward conveyance direction; and a control device which is configured to control the wiping member conveyance device and the reverse conveyance driving device, wherein before the wiping member is brought into contact with the liquid ejection face, the control device controls the wiping member conveyance device to drive the wiping member to be conveyed in the forward conveyance direction while controls the reverse conveyance driving device to drive the wiping member to be conveyed in the reverse conveyance direction so as to tension the wiping member and thereby push down the pressing member to the second position.

According to this aspect of the invention, the configuration can be adopted in which the wiping member is driven in the direction reverse to the forward conveyance direction as the device for suppressing the conveyance movement of the wiping member on the upstream side of the pressing member in the forward conveyance direction of the wiping member.

Preferably, the liquid ejection apparatus further comprises: a pay-out conveyance driving device which is configured to drive the wiping member to be paid out in the forward conveyance direction from the upstream side of the pressing member in the forward conveyance direction, wherein the control device causes the pay-out conveyance driving device to serve as the reverse conveyance driving device by switching a drive direction of the pay-out conveyance driving device to drive the wiping member to be returned in the reverse conveyance direction.

According to this aspect of the invention, by reversely driving the pay-out conveyance driving device, which usually drives the wiping member to be paid out in the forward conveyance direction, it is possible to cause the pay-out conveyance driving device to also serve as the reverse conveyance driving device.

Preferably, before the wiping member is brought into contact with the liquid ejection face, the control device controls the pay-out conveyance driving device to drive the wiping member to be returned in the reverse conveyance direction so as to tension the wiping member and thereby push down the pressing member to the second position, and when the wiping member is brought into contact with the liquid ejection face, the control device controls the pay-out conveyance driving device to drive the wiping member to be paid out in the forward conveyance direction.

According to this aspect of the invention, by performing the control for switching the driving directions of the pay-out conveyance driving device, tensioning and conveying of the wiping member can be appropriately performed.

It is also preferable that the slack elimination mechanism includes: a pressing member driving device which is configured to move the pressing member against the force of the elastic member to the second position; and a control device which is configured to control the wiping member conveyance device and the pressing member driving device, wherein when the control device controls the pressing member driving device to push down the pressing member to the second position, the control device controls the wiping member conveyance device to convey the wiping member in the forward conveyance direction so as to eliminate slack of the wiping member, and when the wiping member is subsequently brought into contact with the liquid ejection face, the control device controls the pressing member driving device to stop pushing the pressing member.

According to this aspect of the invention, as an alternative to or in combination with the mode in which the wiping member is tensioned to push down the pressing member, the configuration can be adopted in which the pressing member is pushed down to the second position by causing an external force to act directly on the pressing member using the pressing member driving device.

Preferably, the pressing member driving device includes a solenoid actuator.

According to this aspect of the invention, the simple configuration is achieved and control can be readily performed.

Preferably, the wiping member is wound around a first core on a pay-out side; and the wiping member conveyance device is configured to drive the wiping member to be paid out from the first core, to pass through the pressing member, and to be taken up onto a second core on a take-up side.

According to this aspect of the invention, the long wiping member is wound in the form of a roll around the first core, and is conveyed from the first core toward the second core through the pressing member.

Preferably, the wiping member conveyance device is configured to drive the wiping member to be conveyed in a direction opposite to a direction of the relative movement of the liquid ejection head with respect to the wiping member caused by the relative movement device.

According to this aspect of the invention, it is possible to achieve effective wiping and cleaning.

Preferably, a conveyance speed of the wiping member caused by the wiping member conveyance device is less than 1/10 of a speed of the relative movement of the liquid ejection head with respect to the wiping member caused by the relative movement device.

According to this aspect of the invention, it is possible to maintain good wiping properties, while suppressing the used amount of the wiping member.

In order to attain the aforementioned object, the present invention is also directed to a cleaning apparatus for a liquid ejection head, comprising: a long wiping member which is configured to come in contact with a liquid ejection face of a liquid ejection head to wipe the liquid ejection face, the liquid ejection face being formed with nozzles configured to eject droplets of liquid; a wiping member conveyance device which is configured to drive the wiping member to be conveyed in a forward conveyance direction in a lengthwise direction of the wiping member; a pressing member which is configured to cause the wiping member to come in contact and pressed against the liquid ejection face when the pressing member is placed at a first position; an elastic member which is configured to elastically deform and apply a force to cause the wiping member to be pressed against the liquid ejection face through the pressing member when the wiping member comes in contact and pressed against the liquid ejection face; and a slack elimination mechanism which is configured to push down the pressing member against the force of the elastic member to a second position lower than the first position before the wiping member is brought into contact with the liquid ejection face to wipe the liquid ejection face by relative movement of the liquid ejection head with respect to the wiping member that is in contact with the liquid ejection head and travels by being driven to be conveyed by the wiping member conveyance device, and is configured to stop pushing the pressing member having been pushed down to the second position so as to move the pressing member along with the wiping member to the first position to bring the wiping member into contact with the liquid ejection face.

In this aspect of the invention, it is possible to combine the composition described in any of the above-described aspects of the invention.

In order to attain the aforementioned object, the present invention is also directed to an inkjet recording apparatus, comprising: a liquid ejection head which has a liquid ejection face formed with nozzles configured to eject droplets of liquid; a medium conveyance device which is configured to convey a recording medium on which the droplets ejected from the liquid ejection head are deposited; the above-described cleaning apparatus; and a relative movement device which is configured to cause the relative movement of the liquid ejection head with respect to the wiping member that is in contact with the liquid ejection head and travels by being driven to be conveyed by the wiping member conveyance device.

In this aspect of the invention, it is possible to combine the composition described in any of the above-described aspects of the invention.

Preferably, a plurality of the liquid ejection heads are arranged in a conveyance path of the recording medium, and the cleaning apparatus is arranged for each of the liquid ejection heads.

According to this aspect of the invention, it is possible to wipe each of the liquid ejection heads in a satisfactory manner. In this aspect of the invention, the “relative movement device” can be a common relative movement device which causes the relative movement of the plurality of heads simultaneously.

According to the present invention, the pressing member is pushed down to the second position before the wiping member is brought into contact with the liquid ejection face of the liquid ejection head. Subsequently, when the wiping member is brought into contact with the liquid ejection face, the push down of the pressing member is released from the second position, the pressing member is pushed up together with the wiping member to the first position by a force of the elastic member, and the wiping member is brought into contact with the liquid ejection face. Accordingly, the wiping member comes in contact and pressed against the liquid ejection face of the liquid ejection head in a slack-free state (including a state where an amount of slack is suppressed to a level at which such slack does not pose a problem). Consequently, it is possible to wipe and clean the liquid ejection face by bringing the wiping member into contact with the liquid ejection face while preventing an occurrence of slack of the wiping member.

According to the present invention, it is possible to suppress the slack of the wiping member which wipes the liquid ejection face of the liquid ejection head, and wiping properties can be improved. Therefore, it is possible to maintain and improve the ejection characteristics of the liquid ejection head and stable droplet ejection becomes possible.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

First Embodiment

FIG. 1is a schematic diagram showing a composition of a liquid ejection apparatus10according to a first embodiment of the present invention. As shown inFIG. 1, the liquid ejection apparatus10includes: a liquid ejection head (hereinafter referred to as the “head”)20; and a wiping unit30, which wipes and cleans a nozzle face22(corresponding to a “liquid ejection face”) of the head20.

The wiping unit30includes: a pay-out side web core34(corresponding to a “first core”), which supplies a long wiping web32(corresponding to a “wiping member”); a take-up side web core36(corresponding to a “second core”), which takes up the wiping web32paid out from the pay-out side web core34; a pressing roller40(corresponding to a “pressing member”), which is arranged in a web conveyance path from the pay-out side web core34to the take-up side web core36so that the wiping web32is wrapped around the pressing roller40to come in contact and pressed against the nozzle face22of the head20; an impelling spring42(corresponding to an “elastic member”), which impels the pressing roller40in the upward direction inFIG. 1(in a direction pressing the pressing roller40toward the nozzle face22of the head20during wiping); and a pair of web drive rollers50, which drives the wiping web32to be conveyed.

Furthermore, the liquid ejection apparatus10includes a relative movement mechanism90(corresponding to a “relative movement device”), which causes relative movement of the head20with respect to the wiping unit30. Here, the embodiment is described in which the head20is moved in parallel to the wiping unit30from the left-hand side toward the right-hand side in the direction indicated with an arrow A inFIG. 1, but the method of relative movement is not limited to this.

For instance, it is also possible to adopt a composition where the head20is stationary and the wiping unit30is moved from the right-hand side toward the left-hand side inFIG. 1(in the direction reverse to the direction of the arrow A), or a composition where both of the head20and the wiping unit30are moved in mutually opposing directions.

The wiping web32is, for example, constituted of a knitted or woven sheet made of ultra-fine fibers of polyethylene terephthalate (PET), polyethylene (PE), nylon (NY), or the like, and is formed in a band shape having the width corresponding to the width of the nozzle face22of the head20to be wiped. The wiping web32is supplied in a state of being wound in the form of a roll around the pay-out side web core34, the front end of the web being fixed to the take-up side web core36.

One end of the pay-out side web core34is fitted on a pay-out spindle (not shown), which is supported horizontally. The pay-out spindle has a dual-tube structure, in which an outer tube is supported rotatably about the periphery of an inner tube. A reverse locking mechanism and a friction mechanism are arranged between the inner tube and the outer tube, and the outer tube can rotate only in one direction (the pay-out direction of the wiping web32; the counter-clockwise direction inFIG. 1) with a uniform resistance.

The take-up side web core36is fitted onto a take-up spindle (not shown), which is supported horizontally and rotatably. The take-up spindle can rotate in one direction (the take-up direction of the wiping web32; the counter-clockwise direction inFIG. 1) in coordination with the rotational driving of the pair of web drive rollers50. A web conveyance motor54drives the web drive rollers50to rotate, and the web conveyance motor54can also serve as a take-up motor to drive the take-up spindle to rotate. The take-up spindle of the take-up side web core36has a dual-tube structure, in which an outer tube is supported rotatably about the periphery of an inner tube. A torque limiter is arranged between the inner tube and the outer tube, and is composed in such a manner that when a load (torque) equal to or greater than a prescribed load is applied, the outer tube slides with respect to the inner tube. By this means, it is possible to prevent the wiping web32from being applied with excessive tension.

The pressing roller40is disposed horizontally, and one end of the spindle part of the pressing roller40is supported rotatably. The pressing roller40can be constituted of an elastic roller capable of elastic deformation, such as a rubber roller. The pressing roller40has a roller width corresponding to the width of the wiping web32, and the pressing roller40is impelled in the upward direction inFIG. 1by the impelling spring42. Then, the wiping web32is impelled in the upward direction inFIG. 1by the force of the impelling spring42through the pressing roller40. When the wiping web32comes in contact with the nozzle face22of the head20, the impelling spring42is elastically deformed or compressed, and the wiping web32is pressed with a prescribed pressure against the nozzle face22by the restoring force created by the elastic deformation of the impelling spring42and the restoring force created by the elastic deformation of the pressing roller40.

The pair of web drive rollers50(corresponding to a “wiping member conveyance device”) drives the wiping web32to be conveyed and is constituted of the pair of rollers arranged to face each other across the wiping web32. The web conveyance motor54is coupled to the pair of drive rollers50, and the wiping web32nipped between the pair of drive rollers50is conveyed by driving the web conveyance motor54. The pair of web drive rollers50is arranged in the vicinity of the take-up side web core36, and the take-up spindle of the take-up side web core36is driven to rotate in coordination with the rotation of the pair of web drive rollers50.

The wiping unit30is provided with a cleaning liquid deposition unit60before the pressing roller40. The wiping unit30further includes in the conveyance path of the wiping web32: a first guide roller72, which guides the wiping web32paid out from the pay-out side web core34to the cleaning liquid deposition unit60; and a second guide roller76, which leads the wiping web32on which the cleaning liquid has been deposited by the cleaning liquid deposition unit60, to the pressing roller40.

The cleaning liquid deposition unit60includes a cleaning liquid deposition roller (transfer roller)62. Although not shown in the drawings, the cleaning liquid deposition unit60further includes: a cleaning liquid tray (container), which stores the cleaning liquid; an anilox roller, which is partially immersed in the cleaning liquid contained in the cleaning liquid tray; a doctor blade, which is in contact with the anilox roller and removes excess liquid on the surface of the anilox roller; an intermediate roller, which rotates while being in contact with the anilox roller, and the like. The cleaning liquid held on the surface of the intermediate roller is transferred to the surface of the cleaning liquid deposition roller (transfer roller)62. The anilox roller is a dosing roller in the surface of which a plurality of cells for holding the cleaning liquid are formed, and has a width corresponding to the width of the wiping web32. The intermediate roller and the cleaning liquid deposition roller62also have widths corresponding to the width of the wiping web32, and the cleaning liquid is supplied to the surface of the cleaning liquid deposition roller62through the anilox roller and the intermediate roller. The cleaning liquid deposition roller62is in contact with the wiping web32and rotates in the same direction as the conveyance direction of the wiping web32. The cleaning liquid held on the surface of the cleaning liquid deposition roller (transfer roller)62is supplied to the wiping web32. Consequently, the cleaning liquid is absorbed in the wiping web32.

In the present embodiment, the application roller system is employed as the cleaning liquid supply device for the wiping web32, but instead of this, it is also possible to employ a composition which deposits the cleaning liquid onto the wiping web32by spraying the cleaning liquid from a cleaning liquid spraying nozzle.

As described above, the wiping web32is provided in the state of rolled on the pay-out side web core34, and can therefore be installed (replaced) in the wiping unit30in this state. More specifically, after the pay-out side web core34has been installed by fitting onto the pay-out spindle, the wiping web32is wrapped in sequence around the first guide roller72, the second guide roller76and the pressing roller40, and the take-up side web core36is fitted onto the take-up spindle, thereby completing installation.

By driving the pair of web drive rollers50to rotate, the wiping web32before wiping is paid out from the pay-out side web core34. The wiping web32that has been paid out is conveyed successively through the first guide roller72, the second guide roller76and the pressing roller40, and is taken up onto and recovered on the take-up side web core36.

The wiping unit30in the present embodiment is provided with a tensioning mechanism80(corresponding to a “slack elimination mechanism”) on the upstream side of a head contact surface of the wiping web32, in other words, on the upstream side of the pressing roller40, in the web conveyance direction. The tensioning mechanism80in the present embodiment includes: a nip roller82(corresponding to a “nip member”), which is arranged to face the first guide roller72and nips the wiping web32with the first guide roller72; an impelling spring84, which impels the nip roller82toward the first guide roller72; and a drive unit86(corresponding to a “nip member drive mechanism”), which drives the nip roller82to move between a nip position and a nip release position. The drive unit86includes a drive source (not shown), such as a motor and a cam, or a solenoid actuator.

When the nip roller82is moved to a nip position (the position where the nip roller82is in contact with the wiping web32) by the drive unit86to nip the wiping web32between the first guide roller72and the nip roller82, the wiping web32is fixed. By driving the wiping web32to be conveyed by the web driving rollers50in this fixed state (a restrained state due to the nipping), the wiping web32is unable to travel and is tensioned. When the wiping web32is tensioned, the pressing roller40is pushed downward inFIG. 1against the impelling force of the impelling spring42.

On the other hand, when the nip roller82is moved to a nip release position (a non-contact position where the nip roller82is separated from the wiping web32) by the drive unit86to release the nipping of the wiping web32, the wiping web32can now be conveyed by the web driving rollers50.

The liquid ejection apparatus10includes a control circuit120(corresponding to a “control device”) as a device that controls the drive unit86of the tensioning mechanism80, the web conveyance motor54, and a motor (hereinafter referred to as the “relative movement motor”)92as a drive source of the relative movement mechanism90. The control circuit120can be constituted of a central processing unit (CPU) and peripheral circuits thereof.

Although not shown inFIG. 1, the liquid ejection apparatus10includes an elevator mechanism which is capable of raising and lowering the wiping unit30in the vertical direction inFIG. 1(the direction of the z axis). With the elevator mechanism, it is possible to change the z-direction position of the wiping unit30, and the height of the uppermost position38of the wiping web32wrapped around the pressing roller40can thereby be varied and adjusted.

The wiping unit30is arranged in such a manner that, in a state before starting the wiping operation (i.e., before bring the wiping web32in contact with the head20), the uppermost position38of the wiping web32wrapped around the pressing roller40is slightly (for example, by approximately 1.5 mm) higher than the position of the nozzle face22.

<Description of Operation of Liquid Ejection Apparatus10>

Next, a wiping and cleaning operation of the head20in the liquid ejection apparatus10according to the present embodiment is described.FIG. 2is a flowchart showing a control procedure during the wiping and cleaning operation of the liquid ejection apparatus10. An operation of the liquid ejection apparatus10is described with reference to this flow chart.

When a wiping instruction to carry out wiping and cleaning is issued and the processing of the flowchart inFIG. 2is started, firstly, the tensioning mechanism80is driven, the wiping web32is nipped by the nip roller82and the first guide roller72, and the wiping web32is fixed (step S11). Subsequently, while maintaining this nipped state, the web conveyance motor54coupled to the web driving rollers50is driven to convey the wiping web32(step S12). At this time, since the wiping web32is fixed by the nip roller82, the wiping web32does not travel but is tensioned, the impelling spring42of the pressing roller40yields to the web conveying force and contracts, and the pressing roller40is moved downward inFIG. 1.

In other words, since the wiping web32is restrained on the upstream side of the pressing roller40in the web conveyance direction, the drive of the web driving rollers50in this state causes the wiping web32to be tensioned. The tension acts as a force that pushes the pressing roller40downward, and the pressing roller40is moved downward inFIG. 1together with the wiping web32.

This state is shown inFIG. 3, in which the relative movement mechanism90and the relative movement motor92shown inFIG. 1are omitted. As shown inFIG. 3, when the web driving rollers50are driven to rotate in the state where the wiping web32is fixed by the tensioning mechanism80arranged on the upstream side of the pressing roller40in the web conveyance direction, the pressing roller40is pushed down by the tension of the wiping web32.

If a position of the pressing roller40when the wiping web32is in contact with the nozzle face22during the cleaning of the nozzle face22is assumed to be a reference position (corresponding to a “first position”, hereinafter referred to as a “reference position during contact”), then, before the wiping web32is brought into contact with the nozzle face22, the tensioning mechanism80and the web driving rollers50collaborate to push down the pressing roller40to a withdrawn position (corresponding to a “second position”, hereinafter referred to as a “pushed-down position before contact”), which is lower than the reference position during contact as shown inFIG. 3.

Once the pressing roller40is moved to the pushed-down position before contact where the uppermost position38of the wiping web32wound around the pressing roller40becomes lower than the position of the nozzle face22of the head20, the web conveyance motor54is temporarily stopped (step S13inFIG. 2).

In this state, the relative movement motor92is driven to move the head20to the wiping position (step S14). Thereby, the head20is moved in the direction of the arrow A inFIG. 3toward the wiping unit30. In accordance with a timing where the head20arrives at the wiping position, the tensioning mechanism80is driven to separate the nip roller82from the wiping web32(to release nipping) (step S15). Moreover, at the same timing, the web conveyance motor54is driven to start to convey the wiping web32(step S16). Accordingly, the pressing roller40is pushed up together with the wiping web32by the force of the impelling spring42, and the wiping web32comes in contact with the head20without slackening. Due to the movement of the pressing roller40to the reference position during contact, the wiping web32is pressed against the nozzle face22by the predetermined pushing pressure. Thus, the wiping of the nozzle face22can be started in a slack-free state.

FIG. 4is a schematic view showing a state where the wiping web32is in contact with the head20. InFIG. 4, the relative movement mechanism90and the relative movement motor92shown inFIG. 1are omitted. As shown inFIG. 4, the wiping web32comes in contact with the nozzle face22, the head20and the wiping unit30are moved relative to each other while causing the wiping web32to travel by the driving of the web driving rollers50, and thereby the nozzle face22of the head20is wiped and cleaned. The wiping position (contact position) of the wiping web32is changed sequentially by moving the head20relatively with respect to the wiping unit30, and the whole area of the nozzle face22is sequentially wiped by the wiping web32. During this relative movement, the wiping web32itself is also conveyed by the web drive rollers50and the contact region (wiping surface) of the wiping web32where the wiping web32is in contact with the nozzle face22is sequentially made new. Consequently, a new wiping surface of the wiping web32is constantly supplied to the wiping section.

Then, the control circuit120judges whether or not wiping and cleaning of the whole area of the nozzle face22has been completed (step S17inFIG. 2), and if it has not yet been completed, the operation of wiping and cleaning is continued. For example, it is possible to judge whether or not wiping and cleaning has been completed, on the basis of a signal from an encoder, or the like, which determines an amount of movement of the relative movement mechanism90.

When the wiping and cleaning has been completed, the relative movement motor92is halted (step S18), and the web conveyance motor54is also halted (step S19). In this way, the wiping and cleaning process is completed.

Thereafter, when the head20is returned to the original position (image forming position), the wiping unit30is lowered until the wiping web32reaches a prescribed withdrawn position at a height where the wiping web32is not in contact with the head20, and the head20is then moved in the direction reverse to the direction of arrow A.

According to the present embodiment, an occurrence of slackening of the wiping web32when the wiping web32is brought into contact with the head20can be prevented. Therefore, wiping of the head20by the wiping web32can be performed in a slack-free state. According to the present embodiment, the head20is not wiped with a soiled surface of the wiping web32and therefore it is possible to improve the head cleaning properties. Thus, it is possible to improve the ejection stability from the head20.

In the first embodiment shown inFIG. 1, a combination of the wiping unit30and the tensioning mechanism80corresponds to a “cleaning apparatus for the liquid ejection head”. Moreover, the tensioning mechanism80corresponds to a “slack elimination mechanism”.

<Relative Movement Speed and Web Conveyance Speed>

The head movement speed (relative movement speed) caused by the relative movement mechanism90and the web conveyance speed are specified by taking overall consideration of the physical properties of the wiping web32, the properties of the cleaning liquid, the controllability of the relative movement mechanism90, the productivity, the used amount of web, and so on. In general, the web conveyance speed is set to a speed sufficiently smaller than the head movement speed (the relative movement speed). For example, the web conveyance speed is set to a speed not greater than 1/10 of the head movement speed. Desirably, the web conveyance speed is set to a speed not greater than 1/20 of the head movement speed. For example, the head movement speed is set to 80 mm/s, and the web conveyance speed is set to 3.2 mm/s.

Second Embodiment

FIG. 5is a schematic drawing showing a composition of a liquid ejection apparatus110according to a second embodiment of the present invention. InFIG. 5, the elements which are the same as or similar to those in the first embodiment described with reference toFIG. 1are denoted with the same reference numerals, and description thereof is omitted here.

In the liquid ejection apparatus110according to the second embodiment shown inFIG. 5, a tensioning device is constituted of a pay-out roller88configured to convey the wiping web32to be paid out and a motor (hereinafter referred to as a “web pay-out motor”)89coupled to the pay-out roller88, in place of the tensioning mechanism80in the liquid ejection apparatus10described with reference toFIG. 1.

The pay-out roller88can come in contact with the wiping web32and rotate, and is capable of conveying the wiping web32in a pay-out direction or a reverse direction that is reverse to the pay-out direction. The web pay-out motor89, which acts as a power source to drive the pay-out roller88, is capable of switching rotational directions. The control circuit120controls the rotational direction and the drive timing of the web pay-out motor89.

FIG. 5shows a state where the web pay-out motor89is driven in the direction reverse to the direction of the normal web conveying. Instead of fixing the wiping web32with the nip roller82of the tensioning mechanism80described with reference toFIG. 1, the web pay-out motor89shown inFIG. 5is rotated in reverse to convey the wiping web32in the reverse direction, thereby the wiping web32is tensioned, and the pressing roller40can be pushed down.

Driving the web pay-out motor89in the direction reverse to the direction of the normal web conveying causes the pay-out roller88to rotate in the counter-clockwise direction inFIG. 5. Due to the rotation (rotation in the reverse direction) of the pay-out roller88, the wiping web32is driven to be conveyed in the reverse direction. Combination of driving of the web driving rollers50in the forward direction and driving of the pay-out roller88in the reverse direction causes the wiping web32to be tensioned, and the tension causes the pressing roller40to be pushed down to the pushed-down position before contact, which is lower than the reference position during contact.

Subsequently, in a similar manner to the first embodiment, the head20is moved to the wiping position by the relative movement mechanism90, and the web conveyance motor54and the web pay-out motor89are driven in the forward direction in accordance with the position of the head20. Accordingly, as shown inFIG. 6, the pressing roller40is pushed up together with the wiping web32by the force of the impelling spring42, and the wiping web32comes in contact with the head20without slackening. Due to the movement of the pressing roller40to the reference position during contact, the wiping web32is pressed against the nozzle face22by the predetermined pushing pressure. Thus, the wiping of the nozzle face22can be started in a slack-free state.

FIG. 6is a schematic view showing a state where the wiping web32is in contact with the head20. InFIG. 6, the relative movement mechanism90and the relative movement motor92shown inFIG. 5are omitted. As shown inFIG. 6, when the web pay-out motor89is driven in the forward direction, the pay-out roller88is caused to rotate in the clockwise direction inFIG. 6, and the wiping web32can be paid out toward the pressing roller40. During the normal web conveying in the wiping operation of the nozzle face22, the wiping web32is conveyed by the forward rotation. The control circuit120controls the web conveyance motor54and the web pay-out motor89to keep a predetermined conveying velocity of the wiping web32.

According to the second embodiment, similarly to the first embodiment, an occurrence of slackening of the wiping web32when the wiping web32is brought into contact with the head20can be prevented. Thereby, the head20is not wiped with a soiled surface of the wiping web32and therefore it is possible to improve the head cleaning properties. Thus, it is possible to improve the ejection stability from the head20.

In the second embodiment described with reference toFIGS. 5 and 6, the combination of the pay-out roller88, which drives the wiping web32to be paid out, and the web pay-out motor89, which is the drive source of the pay-out roller88, is also served as the tensioning mechanism, and when the web pay-out motor89is driven in reverse, the combination of the pay-out roller88and the web pay-out motor89functions as the tensioning mechanism, which inhibits or suppresses travel of the wiping web32in the normal conveyance direction.

In the second embodiment, the combination of the pay-out roller88and the web pay-out motor89corresponds to the “slack elimination mechanism”, the “tensioning mechanism”, and the “pay-out conveying driving device”, and the control circuit120corresponds to the “control device”.

Third Embodiment

FIGS. 7A and 7Bare schematic views showing a substantial part of a liquid ejection apparatus according to a third embodiment of the present invention.FIG. 7Ashows a situation where the pressing roller40has been pushed down to the pushed-down position before contact, andFIG. 7Bshows a situation where the pressing roller40is positioned at the reference position during contact.FIGS. 7A and 7Bare side schematic views from the forward side in the movement direction of the head20caused by the relative movement mechanism90shown inFIG. 1(the direction indicated with the arrow A). For convenience of the drawings, the wiping web32is omitted inFIGS. 7A and 7B.

In place of the tensioning mechanism80of the liquid ejection apparatus10described with reference toFIG. 1, as shown inFIGS. 7A and 7B, a configuration can be adopted which is provided with a displacing mechanism that moves the pressing roller40to the pushed-down position before contact (FIG. 7A) and the reference position during contact (FIG. 7B). The other components are similar to those shown inFIG. 1.

For the third embodiment shown inFIGS. 7A and 7B, a structure for moving the pressing roller40by means of solenoid actuators150is described. The impelling springs42are respectively arranged at shaft sections41on both ends of the pressing roller40, and the shaft sections41are impelled upward inFIG. 7Aby the impelling springs42. The solenoid actuators150are arranged on both sides of the pressing roller40. A movable section152of each solenoid actuator150is coupled with a push-down member154, which can come into contact with the shaft section41of the pressing roller40and regulate a height position of the pressing roller40.

When the solenoid actuators150are driven to extend the movable sections152, the push-down members154coupled to the tips (lower ends inFIG. 7A) of the movable sections152move downward inFIG. 7A. Due to movement of the push-down members154, the shaft sections41of the pressing roller40are pushed downward inFIG. 7Aagainst the impelling force of the impelling springs42and the pressing roller40is displaced to the pushed-down position before contact. In doing so, an amount by which the pressing roller40is pushed down is greater than an amount by which the pressing roller40descends during wiping (for example, 1.5 mm).

When the driving of the solenoid actuators150are stopped, the movable sections152are retracted into the cores and the push-down members154rise as shown inFIG. 7B. At this time, the pressing roller40is lifted by the restoring force of the impelling springs42and the pressing roller40moves to the predetermined reference position during contact.

The driving of the solenoid actuators150is controlled by the control circuit120described with reference toFIG. 1.

Next, an operation according to the third embodiment is described.FIG. 8is a flowchart showing a control procedure during the wiping and cleaning operation of the liquid ejection apparatus according to the third embodiment. An operation of the liquid ejection apparatus is described with reference to this flowchart.

When a wiping instruction to carry out wiping and cleaning is issued and the processing of the flowchart inFIG. 8is started, firstly, the solenoid actuators150are driven to lower the pressing roller40(step S21). Subsequently, the web conveyance motor54is driven to eliminate the slack of the wiping web32caused when the pressing roller40is pushed down (step S22). In other words, a state is created where the wiping web32is not slackened (including a state where an amount of slack is suppressed to a level at which such slack does not pose a problem) while the pressing roller40is being lowered to the pushed-down position before contact (the second position). Thereafter, the relative movement motor92is driven to move the head20to the wiping position (step S23). In accordance with a timing where the head20arrives at the wiping position, the driving of the solenoid actuators150is stopped (step S24).

Thereby, the pressing roller40is lifted (seeFIG. 7B) and brings the wiping web32into contact with the nozzle face22of the head20(step S25inFIG. 8). At this time, the wiping web32is not slackened, because the amount by which the pressing roller40is pushed down in step S21prior to bringing the wiping web32in contact with the nozzle face22is greater than the amount of descending of the pressing roller40during contact. Then, the wiping of the nozzle face22can be started in a slack-free state.

Thus, the wiping web32comes in contact with the nozzle face22, the head20and the wiping unit30are moved relative to each other while causing the wiping web32to travel by the driving of the web driving rollers50, and thereby the nozzle face22of the head20is wiped and cleaned. The wiping position (contact position) of the wiping web32is changed sequentially by moving the head20relatively with respect to the wiping unit30, and the whole area of the nozzle face22is sequentially wiped by the wiping web32. During this relative movement, the wiping web32itself is also conveyed by the web drive rollers50and the contact region (wiping surface) of the wiping web32where the wiping web32is in contact with the nozzle face22is sequentially made new. Consequently, a new wiping surface of the wiping web32is constantly supplied to the wiping section.

Then, the control circuit120judges whether or not wiping and cleaning of the whole area of the nozzle face22has been completed (step S26), and if it has not yet been completed, the operation of wiping and cleaning is continued. For example, it is possible to judge whether or not wiping and cleaning has been completed, on the basis of a signal from an encoder, or the like, which determines an amount of movement of the relative movement mechanism90.

When the wiping and cleaning has been completed, the relative movement motor92is halted (step S27), and the web conveyance motor54is also halted (step S28). In this way, the wiping and cleaning process is completed.

According to the present embodiment, an occurrence of slackening of the wiping web32when the wiping web32is brought into contact with the head20can be prevented. According to the present embodiment, the head20is not wiped with a soiled surface of the wiping web32and therefore it is possible to improve the head cleaning properties. Thus, it is possible to improve the ejection stability from the head20.

In the third embodiment, a combination of the solenoid actuators150and the push-down members154corresponds to the “slack elimination mechanism”.

In the embodiments described above, the relative positioning of the head20and the wiping unit30in the height direction (z direction) is described in terms of raising and lowering the wiping unit30in the vertical direction; however, instead of this or in combination with this, it is also possible to use a mechanism that raises and lowers the head20in the vertical direction.

In the first embodiment, although the configuration has been described in which the wiping web32is nipped and fixed by the nip roller82to restrain the conveyance of the wiping web32by the web driving rollers50so that the wiping web32is tensioned, a configuration can alternatively be adopted in which the wiping web32is not fixed on the upstream side of the pressing roller40in the conveyance direction but gradually conveyed in the forward direction while applying tension (back tension) in the direction reverse to the forward conveyance.

In other words, the configuration can be adopted in which, with respect to the wiping web32partially wound around the pressing roller40, the tension is applied to the wiping web32before and after the pressing roller40in the web conveyance direction to apply a force that pushes down the pressing roller40.

In the second embodiment, although the configuration has been described in which the wiping web32is tensioned using the reverse drive of the web pay-out motor89, a configuration can alternatively be adopted in which a mechanism including a motor, a roller, and the like, is separately arranged for tensioning the wiping web32.

Embodiment of Application in Inkjet Recording Apparatus

Next, an embodiment is described in which the liquid ejection apparatus10or110described above is applied to an inkjet recording apparatus.

FIGS. 9,10and11are a front view diagram, a plan view diagram and a side view diagram, respectively, showing a composition of the principal part of an inkjet recording apparatus210according to an embodiment of the present invention. As shown inFIGS. 9,10and11, the inkjet recording apparatus210is a single-pass type of line printer, and includes: a paper conveyance mechanism220(which corresponds to a “medium conveyance device”) configured to convey paper (cut sheet paper) P, which is a recording medium; a head unit230, which ejects ink droplets of respective colors of cyan (C), magenta (M), yellow (Y) and black (K) toward the paper P which is conveyed by the paper conveyance mechanism220; a maintenance unit240, which carries out maintenance of heads232of the respective colors (corresponding to “liquid ejection heads”) installed on the head unit230; and a nozzle face cleaning apparatus250, which cleans the nozzle faces of the respective heads232installed on the head unit230. The head232inFIG. 9corresponds to the head20inFIGS. 1 and 5, and the nozzle face cleaning apparatus250inFIG. 9corresponds to the wiping unit30inFIGS. 1 and 5.

The paper conveyance mechanism220shown inFIG. 9is constituted of a belt conveyance mechanism, and conveys the paper P holding the paper P on a conveyance face of a travelling belt222by suction.

As shown inFIG. 10, the head unit230includes: a head232C, which ejects cyan (C) ink droplets; a head232M, which ejects magenta (M) ink droplets; a head232Y, which ejects yellow (Y) ink droplets; and a head232K, which ejects black (K) ink droplets. The heads232C,232M,232Y and232K are constituted of line heads, which correspond to the maximum width of the paper P, which is the object of printing.

Since the heads232C,232M,232Y and232K have a common composition, then the following description refers to a head or heads232, unless the particular ink colors are to be distinguished.

The head unit230includes: a head supporting frame234, on which the heads232are installed; and a head supporting frame movement mechanism (not shown), which moves the head supporting frame234.

The head supporting frame234includes a head installation section (not shown) for installing the heads232. The heads232are installed detachably in this head installation section. Furthermore, the head installation section is arranged so as to be raisable and lowerable on the head supporting frame234, and is raised and lowered by an elevator mechanism (not shown). The heads232which are installed on the head installation section are raised and lowered perpendicularly with respect to the conveyance face of the paper P.

The heads232installed on the head supporting frame234are arranged perpendicularly with respect to the conveyance direction of the paper P. Furthermore, the heads232are arranged at a fixed interval apart in a prescribed order in the conveyance direction of the paper P. Although the configuration with the CMYK standard four colors is described in the present embodiment, combinations of the ink colors and the number of colors are not limited to those. As required, light inks, dark inks and/or special color inks can be added. For example, a configuration in which inkjet heads for ejecting light-colored inks such as light cyan and light magenta are added is possible. Moreover, there are no particular restrictions of the sequence in which the heads of respective colors are arranged.

The head supporting frame movement mechanism causes the head supporting frame234to slide horizontally in the direction perpendicular to the conveyance direction of the paper P above the paper conveyance mechanism220. The “head supporting frame movement mechanism” corresponds to the “relative movement mechanism90” inFIG. 1.

The head supporting frame movement mechanism includes, for example: a ceiling frame, which is disposed horizontally above the paper conveyance mechanism220; guide rails, which are arranged on the ceiling frame; a traveling body, which slides over the guide rails; and a drive device, which moves the traveling body along the guide rails (for example, a screw feed mechanism, or the like). The head supporting frame234is installed on the travelling body and slides horizontally.

The head supporting frame234is driven by the head supporting frame movement mechanism, and is arranged movably between a prescribed “image recording position (image formation position)” and a “maintenance position”. The head supporting frame234is arranged above the paper conveyance mechanism220when positioned at the image recording position. Thereby, it is possible to carry out printing onto the paper P conveyed by the paper conveyance mechanism220.

On the other hand, the head supporting frame234is arranged at the position where the maintenance unit240is disposed when the head supporting frame234is situated at the maintenance position.

Caps242(242C,242M,242Y,242K) configured to cover the nozzle faces233of the heads232are arranged in the maintenance unit240. When the inkjet recording apparatus210is halted for a long period of time, for example, the heads232are moved to the position where the maintenance unit240is disposed (the maintenance position) and the nozzle faces233are covered with the caps242. Thus, ejection failure due to drying is prevented.

A pressurizing and suctioning mechanism (not shown) for pressurizing and suctioning the interior of the nozzles and a cleaning liquid supply mechanism (not shown) for supplying cleaning liquid to the interior of the caps242are arranged in the caps242. Furthermore, a waste liquid tray244is arranged at a position below the caps242. The cleaning liquid supplied to the caps242is discarded into the waste liquid tray244and is recovered into a waste liquid tank248from the waste liquid tray244through a waste liquid recovery pipe246.

The nozzle face cleaning apparatus250is arranged between the paper conveyance mechanism220and the maintenance unit240. The nozzle face cleaning apparatus250cleans the nozzle faces233by wiping the nozzle faces233of the heads232with wiping webs312when the head supporting frame234is moved from the image recording position to the maintenance position. Each of the wiping webs312corresponds to the wiping web32shown inFIG. 1.

The nozzle face wiping apparatus250includes: a wiping apparatus main body frame252; wiping units300C,300M,300Y and300K, which are installed on the wiping apparatus main body frame252; and a wiping apparatus main body elevator device (not shown), which raises and lowers the wiping apparatus main body frame252.

The wiping units300C,300M,300Y and300K respectively make the wiping webs312in contact with the nozzle faces233of the heads232while causing the band-shaped wiping webs312to travel, thereby wiping the nozzle faces233. The wiping units300C,300M,300Y and300K are arranged for the respective heads232, and are arranged on the wiping apparatus main body frame252in accordance with the installation pitch of the heads232. The wiping units300C,300M,300Y and300K all have the same composition and therefore the composition is described here with respect to one wiping unit, which is referred to as the wiping unit300. The composition of the wiping unit300is similar to the composition of the wiping unit30described with reference toFIGS. 1 and 5.

<Embodiment of Composition of Head>

FIG. 12is a plan view perspective diagram of the head232. A plurality of nozzles235configured to eject ink droplets are formed in the nozzle face233of the head232. The head232according to the present embodiment is constituted of a so-called matrix head, in which the plurality of nozzles235are arranged in a two-dimensional matrix configuration. By adopting the composition in which the nozzles are arranged in the two-dimensional fashion on the nozzle face233, it is possible to reduce the interval between the nozzles which are effectively arranged in the lengthwise direction of the head232(the paper width direction, which is perpendicular to the paper conveyance direction), and high recording resolution can be achieved.

In the case of the inkjet head (matrix head) having the two-dimensional nozzle arrangement, a projected nozzle row in which the nozzles in the two-dimensional nozzle arrangement are projected (by orthogonal projection) to an alignment in a direction (corresponding to a “main scanning direction”) that is perpendicular to the medium conveyance direction (corresponding to a “sub-scanning direction”) can be regarded as equivalent to a single nozzle row in which the nozzles are arranged at roughly even spacing at a nozzle density that achieves the recording resolution in the main scanning direction (the medium width direction). Here, “roughly even spacing” means substantially even intervals between the droplet deposition points which can be recorded by the inkjet printing system. For example, the concept of “even spacing” also includes cases where there is slight variation in the intervals, to take account of manufacturing errors or movement of the droplets on the medium due to landing interference. Taking account of the projected nozzle row (also referred to as the “effective nozzle row”), it is possible to associate the nozzle positions (nozzle numbers) in the alignment sequence of the projected nozzles which are aligned following the main scanning direction. In the description given below, reference to “nozzle positions” means the positions of the nozzles in the effective nozzle rows.

In implementing the present embodiment, the mode of arrangement of the nozzles235in the head232is not limited to the embodiment shown inFIG. 12, and it is possible to adopt various nozzle arrangements. For example, instead of the matrix arrangement shown inFIG. 12, it is possible to use a linear arrangement in one row, a V-shaped nozzle arrangement and a bent line-shaped nozzle arrangement such as a zig-zag shape (W shape, or the like) in which the V-shaped nozzle arrangement is repeated.

An image of a prescribed recording resolution (for example, 1200 dpi) can be recorded on an image formation region of the paper P (recording medium), by performing just one operation of relatively moving the paper P with respect to the head232provided with the nozzle row of this kind (in other words, by a single sub-scanning action).

The head232according to the present embodiment ejects ink droplets from nozzles235by a so-called piezoelectric method. Each of the nozzles235is connected to a pressure chamber236, and a droplet of ink is ejected from the nozzle235by causing a wall face of the corresponding pressure chamber236(for example, the upper face of the pressure chamber236when the ejection direction of droplet from the nozzle235is a downward direction) to vibrate by a piezoelectric element (not shown). The devices for generating ejection pressure (ejection energy) for ejecting the droplets from the nozzles in the inkjet head are not limited to the piezoelectric actuators (piezoelectric elements), and it is also possible to employ pressure generating elements (ejection energy generating elements) of various types, such as electrostatic actuators, heaters in a thermal method (a method which ejects ink by using the pressure created by film boiling upon heating by heaters) or actuators of various kinds based on other methods. A corresponding energy generating element is arranged in the flow channel structure in accordance with the ejection method of the head.

The nozzle face cleaning apparatus250wipes the respective nozzle faces233by causing the wiping webs312to slide over the nozzle faces233of the heads232, during the course of the movement of the heads232from the image recording position to the maintenance position.

The nozzle face cleaning apparatus250is situated at a prescribed standby position when cleaning is not being performed, and during the cleaning, is situated at a prescribed operating position, which is raised by a prescribed amount with respect to the standby position. Furthermore, when the nozzle face cleaning apparatus250is situated in the prescribed operating position, it is possible to wipe the nozzle faces233with the wiping units300. In other words, the wiping webs312can come in contact and pressed against the nozzle faces233when the heads232pass over the wiping units300.

When a nozzle face cleaning instruction is applied and the inkjet recording apparatus210enters into nozzle face cleaning mode, the slack elimination mechanisms in the nozzle face cleaning apparatus250are driven to prepare the wiping webs312to be in the non-slackened state, and the heads232are moved from the image recording position to the maintenance position. When the heads232reach the prescribed positions, the wiping webs312are conveyed in the direction opposite to the direction of travel of the heads232and brought into contact with the nozzle faces233of the heads232in the slack-free state. By wiping the nozzle faces233through causing the wiping webs312to travel in the direction opposite to the direction of movement of the nozzle faces233, it is possible to wipe the nozzle faces233efficiently. Furthermore, it is also possible to wipe each nozzle face233always using a new surface (unused region) of the wiping web312.

In the embodiments described above, the inkjet recording apparatus using the page-wide full-line type heads having the nozzle rows of the lengths corresponding to the full width of the recording medium (the single-pass image forming apparatus, which completes an image by a single sub-scanning action) has been described; however, the application of the present invention is not limited to this, and the present invention can also be applied to an inkjet recording apparatus which performs image recording by means of a plurality of scanning actions over a recording medium by moving a short recording head, such as a serial head (shuttle scanning head), or the like.

<Head Movement Direction During Wiping and Cleaning>

In the embodiments described above, the nozzle face is wiped and cleaned while the head is moved from the image recording position to the maintenance position; however, instead of this or in combination with this, it is also possible to wipe and clean the nozzle face during the movement of the head from the maintenance position to the image recording position.

Moreover, in the embodiments described above, the wiping member has the width corresponding to the width of the nozzle face of the head in the breadthwise direction, and the nozzle face is wiped in the lengthwise direction; however, the wiping direction is not limited to this direction. For example, it is also possible that a wiping member that has the width corresponding to the length of the nozzle face in the lengthwise direction is used to wipe the nozzle face in the breadthwise direction.

In either of these modes, the slack eliminating member is arranged to the outside of the nozzle formation region, taking account of the relative movement direction of the head with respect to the wiping member, in such a manner that the wiping member comes in contact with the slack eliminating member before the wiping member comes in contact with the nozzle face of the head (the nozzle formation region).

<Device for Causing Relative Movement of Head and Recording Medium>

In the embodiments described above, the embodiments are given in which the recording medium is conveyed with respect to the stationary head, but in implementing the present invention, it is also possible to move a head with respect to a stationary recording medium (image formation receiving medium), or move both of the head and the recording medium.

The full line type recording head based on the single pass method is normally arranged in the direction perpendicular to the feed direction (conveyance direction) of the recording medium; however, a mode is also possible in which the head is arranged in an oblique direction forming a certain prescribed angle with respect to the direction perpendicular to the conveyance direction. In this case also, it is possible to specify the effective nozzle row direction, and the like, by defining two mutually intersecting axes (a first direction and a second direction).

Furthermore, in the embodiments described above, the paper conveyance mechanism220based on the belt conveyance method is given as an example of the medium conveyance device; however, the conveyance method is not limited to the belt conveyance method and it is also possible to adopt a drum conveyance method, which conveys a recording medium by wrapping the recording medium around the circumferential surface of the drum.

In the embodiments described above, the nozzle face of the head is taken to be in the horizontal plane, and the droplet ejection direction is taken to be the vertically downward direction; however, it is also possible to adopt a composition in which the nozzle face of the head is inclined at a prescribed angle with respect to the horizontal plane. In this case, the contacting surface of the wiping web is also inclined in accordance with the inclination of the nozzle face. Furthermore, a composition is adopted in which the flat surface section of the slack eliminating member is arranged to form the same plane with the nozzle face.

The “recording medium” is a general term for a medium on which dots are recorded by droplets ejected from the liquid ejection head, and this includes various terms, such as print medium, recorded medium, image formation medium, image receiving medium, deposition receiving medium, print sheet, and the like. In implementing the present invention, there are no particular restrictions on the material or shape, or other features, of the recording medium, and it is possible to employ various different media, irrespective of their material or shape, such as continuous paper, cut paper, seal paper, OHP sheets or other resin sheets, film, cloth, nonwoven cloth, a printed substrate on which a wiring pattern, or the like, is formed, or a rubber sheet.

<Application Examples of the Apparatus>

In the embodiments described above, application to the inkjet recording apparatus for graphic printing has been described, but the scope of application of the present invention is not limited to this. For example, the present invention can also be applied widely to inkjet apparatuses which obtain various shapes or patterns using liquid function material, such as a wire printing apparatus for forming an image of a wire pattern for an electronic circuit, manufacturing apparatuses for various devices, a resist printing apparatus using resin liquid as a functional liquid for ejection, a color filter manufacturing apparatus, a fine structure forming apparatus for forming a fine structure using a material for material deposition, or the like.