Inkjet recording apparatus

An inkjet recording apparatus includes a record head having an ejection surface and a conveyance mechanism having a conveyance surface which passes through a position facing the ejection surface. The inkjet recording apparatus further includes: a capping mechanism which has a annular component provided around the record head to circumscribe the record head and is able to achieve capping such that the ejection surface is covered with the conveyance surface and the annular component as the annular component is caused to contact the conveyance surface; a recognition unit which recognizes a position of a first region on the conveyance surface, the first region being not smaller than an enclosed range on the conveyance surface which range is circumscribed by the annular component and being a region in which a predetermined amount or less ink adheres to an arbitrary range which is within the first region and is identical in size with the enclosed range; and a control unit which controls the capping mechanism and the conveyance mechanism so that the capping is achieved in such a way that the first region of the conveyance surface recognized by the recognition unit contacts the annular component.

CROSS REFERENCE TO RELATED APPLICATION

The present application claims priority from Japanese Patent Application No. 2010-149589, which was filed on Jun. 30, 2010, the disclosure of which is herein incorporated by reference in its entirety.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to an inkjet recording apparatus recording an image onto a recording medium.

2. Description of the Related Art

A known inkjet recording apparatus caps the nozzle surface (ejection surface) of a record head by a cap and a conveyance belt in such a way that the cap provided around the record head is caused to closely contact the conveyance belt.

SUMMARY OF THE INVENTION

According to this known inkjet recording apparatus, the capping of the ejection surface, i.e. the formation of a closed space defined by the ejection surface, the cap, and the conveyance belt, is carried out by causing the cap to closely contact a desired portion of the surface of the conveyance belt. When the capping is in action, aqueous ink adhering to the surface of the conveyance belt opposing the ejection surface is often dry ink which adhered to the surface while ago, in other words, thickened ink. Since such thickened ink absorbs moisture from the surrounding atmosphere (i.e. is hygroscopic), the moisture of the ink inside the ejection opening is reduced. For this reason, the ink inside the ejection opening gets dry even if the capping is in action.

An object of the present invention is to provide an inkjet recording apparatus in which ink in ejection openings is hardly dried while the capping is in action.

The inkjet recording apparatus of the present invention includes a recording head, a conveyance mechanism, a capping mechanism, a recognition unit, and a control unit. The record head has an ejection surface on which a plurality of ejection openings ejecting aqueous ink are funned. The conveyance mechanism has a conveyance surface passing through a position facing the ejection surface and conveys, by moving the conveyance surface in a travel direction, a recording medium supported on the conveyance surface so as to cause the recording medium to pass through the position facing the ejection surface. The capping mechanism has a annular component provided around the record head to circumscribe the record head and is able to achieve capping such that the ejection surface is covered with the conveyance surface and the annular component as the annular component is caused to contact the conveyance surface. The recognition unit recognizes a position of a first region on the conveyance surface, the first region being not smaller than an enclosed range on the conveyance surface which range is circumscribed by the annular component and being a region in which a predetermined amount or less ink adheres to an arbitrary range which is within the first region and is identical in size with the enclosed range. The control unit controls the capping mechanism and the conveyance mechanism so that the capping is achieved in such a way that the first region of the conveyance surface recognized by the recognition unit contacts the annular component.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

First, the overall structure of an inkjet printer1according to embodiment of the present invention will be described with reference toFIG. 1,FIG. 2A, andFIG. 2B.

The printer1has a rectangular parallelepiped chassis1a. On top of the chassis1ais provided an area31where ejected sheets are stacked. The inside space of the chassis1ais divided into spaces A, B, and C sequentially from the top. The spaces A and B are spaces having therein a conveying path connected to the area31. The space C accommodates four ink cartridges39serving as an ink supply source for supplying ink to inkjet heads10.

In the space A are disposed four inkjet heads10(hereinafter, heads10), a capping mechanism70restraining the thickening of ink in the four heads10which are record heads ejecting magenta, cyan, yellow, and black inks, a capping mechanism70restraining the thickening of ink in each head10, a conveying unit21which conveys a sheet P in a conveyance direction (left to right inFIG. 1), a wiping mechanism60which is wiping means provided around the lower edge of the conveying unit21, and a guide unit which guides the sheet P. On top of the space A is a control unit1p. The control unit1pcontrols operations of various parts of the printer1so as to administrate the entire operation of the printer1.

The control unit1pcontrols recording operations (conveying sheets P by various components of the printer1, ejection of ink in sync with the conveyance of sheets P, or the like), based on image data supplied from an external apparatus. In response to a maintenance instruction, the control unit1pcontrols the conveying unit21, the wiping mechanism60, and the capping mechanism70. The maintenance indicates a capping operation to cap the ejection surfaces10aof the four heads10and/or a wiping operation to remove foreign matters (ink, paper powder, or the like) on the outer surface8aof the conveyance belt8when the capping is performed. The details of the maintenance will be given later with reference toFIG. 8.

The conveying unit21includes belt rollers6and7, an endless conveyance belt8which is stretched between the rollers6and7and has a surface (conveyance surface)8awhich passes through positions opposing the ejection surfaces10aof the heads10, a nipping roller4and a peeling plate5provided outside the conveyance belt8, and an attracting platen22provided inside the conveyance belt8. The belt roller7is a drive roller which is rotated clockwise inFIG. 1by a conveyance motor121(seeFIG. 6) driven by the control unit1p. As the belt roller7rotates, the conveyance belt8moves in the direction indicated by the thick arrow inFIG. 1. The belt roller7is provided with an encoder80(seeFIG. 6). The number of rotations of the belt roller7is measured by this encoder80. The belt roller6is a driven roller which is rotated anticlockwise inFIG. 1in accordance with the travel of the conveyance belt8.

The conveyance belt8is made of a material such as polyimide and fluororesin, has a volume resistivity of about 108 to 1014 ohm centimeters, and is flexible. Alternatively, the conveyance belt8may be made of another material having a similar volume resistivity and flexibility. The conveyance belt8forms a ring and the outer surface8aalso forms a ring. As shown inFIG. 2AandFIG. 2B, the outer surface8ais provided with a preliminary ejection region H which is long in the main scanning directions. The preliminary ejection region H is a region to which later-described preliminary ejection is carried out. The liquid repellent coating is applied onto the region by means of fluororesin or silicon water repellent, and hence the region has higher liquid repellency than the other regions on the outer surface8a. When the conveyance belt8is made of fluororesin, the preliminary ejection region H is coated with fluororesin which includes a larger amount of fluorine than the fluororesin of which the conveyance belt8is made. The preliminary ejection region H is formed across the entire width of the conveyance belt8. Moreover, the preliminary ejection region H is shorter than the sheet P and a later-described sub wiper51, in the sub-scanning directions. The sub-scanning directions indicate the directions in parallel to the conveyance direction of sheets P by the conveying unit21, whereas the main scanning directions indicate directions orthogonal to the sub-scanning directions in the horizontal plane. On the outer surface8ais provided an unillustrated mark which opposes a later-described sheet sensor20. Since the reflectance of the mark is different from that of the outer surface8a, the mark is detectable by the sheet sensor20. The control unit1pis able to grasp the position of the preliminary ejection region H on the outer surface8awith reference to the position of the mark and the number of rotations of the belt roller7.

The attracting platen22includes, as shown inFIG. 1,FIG. 2A, andFIG. 2B, a plate-shaped base32made of an insulating material, two electrodes33and34adhered to the upper surface32aof the base32, and a protective film23adhering to the upper surface32ato entirely cover the electrodes33and34. The attracting platen22is arranged to face the four heads10across the conveyance belt8so as to support the upper loop portion of the conveyance belt8from the inside. The electrodes33and34form a comb shape such that a plurality of long portions33aand34aextending along the sub-scanning directions are connected with one another at their proximal ends. The long portions33aand the long portions34aare alternately provided in the main scanning directions. The electrodes33and34are connected to a power source36(secFIG. 6) which is provided in the chassis1a. This power source36is controlled by the control unit1p. The attracting platen22and the power source36constitute a attracting unit which attracts a sheet P onto the outer surface8aof the conveyance belt8.

The protective film23is made of a material such as polyimide fluororesin and has a volume resistivity of about 108 to 1014 ohm centimeters. Alternatively, the protective film23may be made of another material having a similar volume resistivity.

The nipping roller1made of a conductive material is provided at the upstream end of the attracting platen22in the conveyance direction and faces the long portions33aand34aof the electrodes33and34. The nipping roller4presses a sheet P sent out from the sheet supply unit1bonto the outer surface8aof the conveyance belt8.

With the arrangement above, the conveyance belt8is moved by rotating the belt roller7clockwise inFIG. 1under the control of the control unit1p. As the conveyance belt8is moved, the belt roller6and the nipping roller4are rotated. While a sheet P is conveyed on the conveyance belt8, different electric potentials are applied to the two electrodes33and34under the control of the control unit1p, respectively. (For example, a positive (e.g. 1 kV) or negative electric potential is applied to the electrode33whereas a ground potential is applied to the electrode34.)

When the electric potentials are applied to the two electrodes33and34in this manner, the nipping roller4is conductive and hence, at the portion facing the nipping roller4, an electric current flows from the electrode33(long portion33a) to the nipping roller4via the protective film23, the conveyance belt8, and the sheet P, and also flows from the nipping roller4to the electrode34(long portion34a) via the sheet P, the conveyance belt8, and the protective film23. As a result, a positive or negative electric charge is generated at a portion of the conveyance belt8which faces the sheet P, and an electric charge whose polarity is opposite to that electric charge is induced at the surface of the sheet P facing the conveyance belt8. As these opposing electric charges attract each other, the attracting force attracting the sheet P onto the conveyance belt8is generated.

In the meanwhile, at a portion not facing the nipping roller4, an electric current flows from the electrode33(long portion33a) to the sheet P via the protective film23and the conveyance belt8, and also flows from the sheet P to the electrode34(long portion34a) via the conveyance belt8and the protective film23. Since the resistance of the sheet P in this case is significantly higher than that of the nipping roller4, the overall resistance of this path is higher than the overall resistance of the path which passes through the nipping roller4. For this reason, even though the same electric potentials are applied to the respective electrodes33and34, the electric current on the path passing through the nipping roller4is larger than that of the other path. The Johnsen-Rahbek force between the conveyance belt8and the sheet P, i.e. the attracting force generated by the attracting platen22, increases as the current flowing between the conveyance belt8and the sheet P increases. In other words, as the electric current is increased, the attracting force at the portion facing the nipping roller4becomes larger than in the remaining portions.

As such the sheet P sent out from the sheet supply unit1bis attracted to the outer surface8aat the portion where the attracting force is significantly large (i.e. at the portion facing the nipping roller4). The sheet P is conveyed while being supported and attracted by the other portions (i.e. the portions not facing the nipping roller4), as the conveyance belt8moves in the travel direction. When the sheet P conveyed while being attracted onto the outer surface8aof the conveyance belt8passes through the region immediately below each head10, i.e. passes through the region facing each ejection surface10a, the control unit1pcontrols each head10so that the head10discharges the ink of the corresponding color onto the sheet P. As a result, a desired color image is formed on the sheet P. The peeling plate5is arranged to face the belt roller7. This peeling plate5peels the sheet P off from the outer surface8aand sends the same toward the downstream of the conveyance direction.

The wiping mechanism60includes a main wiper41, a sub wiper51, and a wiper cleaner45. The components of the wiping mechanism60are arranged to face the outer circumferential surface of the lower loop portion of the conveyance belt8. Inside the conveyance belt8, a platen9is provided to face the wipers41and51across the conveyance belt8and to support the lower loop portion of the conveyance belt8from the inside. When the wipers41and51remove foreign matters, the platen9prevents the conveyance belt8from being warped by the pressures exerted by the wipers41and51. This equalizes the contact pressures of the wipers41and51onto the conveyance belt8, thereby ensuring a good wiping performance. The details of the structure of the wiping mechanism60will be given later with reference toFIG. 3andFIG. 4AtoFIG. 4G.

Each head10is, as shown inFIG. 1andFIG. 2A, a substantially rectangular parallelepiped line-type head which is long in the main scanning directions. The lower surface of each head10is the ejection surface10awhere a plurality of ejection openings10bare formed. For recording, i.e. for image formation, the ejection surfaces10aof the respective heads10eject black, magenta, cyan, and yellow inks. These four heads10are aligned in the sub-scanning directions. Each of these heads10is provided so that the ejection surface10afaces the outer surface8aof the upper loop portion of the conveyance belt8and a gap suitable for recording is formed between the ejection surface10aand the outer surface8a.

The guide unit includes an upstream guide unit provided between the conveying unit21and the sheet supply unit1band a downstream guide unit provided between the conveying unit21and the area31. The upstream guide unit includes two guides27aand27band a pair of forwarding rollers26. The downstream guide unit includes two guides29aand29band two pairs of forwarding rollers28.

In the space B, the sheet supply unit1bis detachably attached to the chassis1a. The sheet supply unit1bhas a sheet feeding tray24and a pickup roller25. The sheet feeding tray24is an open-top box and in which plural types of sheets P having different sizes cam be stacked and stored. The pickup roller25sends out the topmost sheet P in the sheet feeding tray24and supplies the sheet P to the upstream guide unit.

As such, in the spaces A and B, a conveying path is formed from the sheet supply unit1bto the area31via the conveying unit21. Based on a recording instruction supplied from an external apparatus, the control unit1pdrives, in accordance with a predetermined sequence, a pickup motor125(seeFIG. 6) connected to the pickup roller25, a feed motor127(seeFIG. 6) connected to the forwarding rollers of each guide unit, and a conveyance motor121(seeFIG. 6). The sheet P sent out from the sheet feeding tray24is supplied to the conveying unit21by the forwarding rollers26. In so doing, the control unit1pcontrols the power source36so as to cause the sheet P supplied to the conveyance belt8to be attracted onto the outer surface8a. When the sheet P passes through the region immediately below each head10in the conveyance direction, the control unit1acontrols the heads10so that inks having corresponding colors are ejected from the respective heads10and a color image is formed on the sheet P. The ejection of ink is carried out based on a detection signal from the sheet sensor20. The sheet sensor20is, as shown inFIG. 2A, provided around one end of the conveyance belt8in the sub-scanning directions, and hence it can detect the leading edge of the conveyed, sheet P. After passing through the regions immediately below the four heads10, respectively, the sheet P is peeled off by the peeling plate5. The sheet P is then conveyed upward by the two forwarding rollers28and, is ejected to the area31through an upper opening30. On the downstream in the conveyance direction of the peeling plate5, a sheet sensor81is provided. The control unit1.pdetermines that paper jam has occurred, when the sheet P conveyed in the conveyance direction is not detected by the sheet sensor81after a predetermined time has passed from the detection of the sheet P by the sheet sensor20. The sheet sensor81is not necessarily provided downstream of the peeling plate5in the conveyance direction. The sheet sensor81is only required to be provided downstream of the heads10.

In the space C, a cartridge unit1cis detachably attached to the chassis1a. This cartridge unit1cincludes a tray35and four cartridges39aligned in the tray35. Each cartridge39stores magenta, cyan, yellow, or black ink. The cartridge39supplies the ink to the corresponding head10via an unillustrated tube. The inks in the present embodiment are aqueous ink. More specifically, such aqueous ink includes water, a moistening agent, a penetrant, and a colorant. The moistening agent is either glycerine or diethylene glycol. The moistening agent restrains ink drying, i.e. the reduction in the moisture in the ink. In this regard, however since the concentration of the moistening agent is high in the thickened ink which is dry and has a reduced amount of moisture, the moistening agent adversely functions as a moisture absorbent absorbing moisture from the surrounding ink. In other words, because of the hygroscopic properly of the moistening agent, the thickened ink absorbs moisture from the surrounding non-dry ink.

Now, the structure of the wiping mechanism60will be described with reference toFIG. 3andFIG. 4AtoFIG. 4G. As shown inFIG. 3, the wiping mechanism60includes a main wiping mechanism40and a sub wiping mechanism50.

The main wiping mechanism40includes a main wiper41and a wiper cleaner45. The main wiper41is used for later-described first wiper drive. This main wiper41is a blade made of an elastic material such as rubber, and is long in the main scanning directions. The proximal end, i.e. the lower end of the main wiper41is fixed to the circumferential surface of the shaft42. The shaft42extends along the main scanning directions and is swingably supported by a frame62. As the shaft42rotates, the main wiper41swings about the shaft42. The frame62is fixed to the chassis1a(seeFIG. 1).

The main wiping mechanism40includes, as components for rotating the shaft42, a gear43afixed to the output shaft of a motor41M, a gear43bengaged with the gear43a, and a worm gear43crotated in accordance with the rotation of the gear43b. At one end of the shaft42, a worm wheel42gis provided to be engaged with the circumferential surface of the worm gear43c. As the gears43a,431), and43care rotated by the motor41M, the worm wheel42gis rotated. Because of the above, the shaft42rotates about its shaft extending along the main scanning directions, with the result that the tilt angle of the main wiper41is changed with respect to the horizontal plane.

The tilt angle of the main wiper41is controlled by the control unit1pso that the leading end part of the main wiper41contacts and is warped by the outer surface8aof the conveyance belt8during the first wiper drive whereas the leading end of the main wiper41is distanced from the outer surface8aof the conveyance belt8when the first wiper drive is not carried out. In particular, the tilt angle of the main wiper41is controlled by the control unit1pso that, when the first wiper drive is not carried out, the leading end of the main wiper41contacts the wiper cleaner45during later-described wiper cleaning whereas the leading end of the main wiper41is distanced from the wiper cleaner45when the wiper cleaning is not carried out.

The main wiper41is slightly longer in the main scanning directions than the width of the conveyance belt8and is formed across the entire width of the conveyance belt8. In other words, the main wiper41is provided so that its center in the main scanning directions corresponds to the center of the conveyance belt8in the width directions and in a plan view the main wiper41protrudes from the both sides of the conveyance belt8in the width directions. The leading edge of the main wiper41contacts the entire width of the conveyance belt8during the first wiping. As a result of the first wiper drive, most of the foreign matters are removed from the region of the outer surface8awhich region is wiped by the main wiper41. This prevents the foreign matters adhering to the outer surface8afrom adhering to the back side of the sheet P on the conveyance belt8and avoids a problem that the conveyance belt cannot convey the sheet P as the foreign matters adhering to the outer surface8alower the force of attracting the sheet P onto the conveyance belt8.

The wiper cleaner45used for the wiper cleaning is constituted by, for example, an absorbent such as sponge. The wiper cleaner45is tube-shaped and extends in the main scanning directions, and pivoted at the shaft46. The shaft46extends along the main scanning directions and rotatably supported by the frame62. As the shaft46rotates, the wiper cleaner46rotates.

The main wiping mechanism40includes, as components used for rotating the shaft46, a pulley47fixed to the output shaft of a motor45M, a pulley46pfixed to one end of the shaft46, and a belt48stretched between the pulley46pand the pulley47. As the pulley47is rotated by the motor45M, the belt48moves and the pulley46protates. As a result, the shaft46rotates with the wiper cleaner45.

The sub wiping mechanism50includes a sub wiper51and a sub wiper cleaner55a, and is provided downstream of the main wiping mechanism40in the travel direction of the conveyance belt8. The sub wiper51is used for later-described second wiper drive. The sub wiper51is a blade made of an elastic material such as rubber and extends in the sub-scanning directions. The length of the sub wiper51in the sub-scanning directions is longer than the length of the preliminary ejection region H in the sub-scanning directions. The proximal end, i.e. the lower end of the sub wiper51is fixed to a wiper supporter51a. This wiper supporter51aextends in the sub-scanning directions. At the both ends of the wiper supporter51ain the sub-scanning directions, sliders52are provided, respectively. The wiper supporter51ais supported by the pair of sliders52so as to be swingable about the axis along the sub-scanning directions. As the wiper supporter51aswings, the sub wiper51also swings. The sub wiper51and the wiper supporter51aare biased clockwise inFIG. 1Aby an unillustrated biasing component such as a spring. The pair of sliders52are supported by a pair of bars53to be movable in the main scanning directions. The pair of bars53extend in the main scanning directions and are inserted into holes penetrating the sliders52. As the pair of sliders52move in the main scanning directions, the sub wiper51also moves in the main scanning directions.

The sub wiping mechanism50includes, as components for moving the sub wiper51in the main scanning directions, a pair of endless belts54, pulleys54a1and54a2around which the pair of belts54travel, a roller54baround which the pair of belts54travel, and pulleys54b1and54b2provided at the respective ends of the roller54b. On the lower loop portion of each belt54, a single slider52is fixed. The sub wiping mechanism50further includes a gear54cwhich rotates together with the pulley54b2and a gear54dwhich is engaged with the gear54cand fixed to the output shaft of the motor59M. As the gears54cand54dare rotated by the motor59M, the pulley54b2rotates. Then the rotation of the pulley54b2causes the roller54bto rotate, with the result that the pair of belts54move. The sliders52therefore move in the main scanning directions while supporting the wiper supporter51a.

The sub wiping mechanism50also includes a plate58below the wiper supporter51a, as a component for rotating the sub wiper51. This plate58is long in the main scanning directions and is in parallel to the horizontal plane. As shown inFIG. 4A, while the sub wiper51is moving in the main scanning direction, the lower edge of the wiper supporter51aslides on the upper surface of the plate58.

The upper surface of the plate58is flat except at the both ends in the main scanning directions. At one end of the plate58in the main scanning directions (i.e. at the end on the upstream of the movement direction (indicated by the arrow inFIG. 3) of the sub wiper51during the wiping operation), a lowered part58ais provided. At the other end of the plate58is provided a slope58b. The lowered part58ais lower than a part of the upper surface of the plate58which part is different from the both end parts of the upper surface in the main scanning directions. On the upper surface of the plate58, an ear portion58a1is provided at the border between the lowered part58aand the remaining part of the plate58. The ear portion58a1selectively takes, as discussed later, a protruding position at which it protrudes from the upper surface of the plate58and a retracted position at which it does not protrude from the upper surface of the plate58.

The sub wiper cleaner55acleans the sub wiper51after the second wiper drive and is made of an absorbent such as sponge. The sub wiper cleaner55ais tube-shaped and extends along the sub-scanning directions, and is pivoted at the shaft55b. The shaft55bextends in the sub-scanning directions and is rotatably supported by the frame62. As the shaft55brotates, the sub wiper cleaner55aalso rotates.

The sub wiping mechanism50includes, as components for rotating the shaft55b, a pulley57fixed to the output shaft of a motor51M, a pulley55a1fixed to one end of the shaft55b, and a belt56stretched between the pulley57and the pulley55a1. As the pulley57is rotated by the motor51M, the belt56moves and the pulley55a1rotates. Consequently, the shaft55brotates with the sub wiper cleaner55aabout the axis extending in the sub-scanning directions. The ear portion58a1is arranged to be movable between a protruding position at which it protrudes upward from the upper surface of the plate58except the both edges of the upper surface in the main scanning directions and a retracted position at which it is retracted into the plate58so as to be flush with the upper surface of the plate58except the both edges of the upper surface in the main scanning directions. The ear portion38a1is biased upward by an unillustrated mechanism and is therefore at the protruding position when no external force is exerted thereto.

Now, the operation of the sub wiper51during the second wiper drive will be described. The second wiper drive is an operation such that the sub wiper51moves along the main scanning directions while contacting the outer surface8aof the conveyance belt8to remove foreign matters from the outer surface8a.

When the second wiper drive is not carried out, as shown inFIG. 4A, the sub wiper51is at a home position at one end of the plate58in the main scanning directions. At this home position, the sub wiper51vertically faces the outer surface8aof the conveyance belt8and is stationary at a tilt angle with which the leading end thereof does not contact the outer surface8a. At this position, as shown inFIG. 4B, the lower end51a1of the wiper supporter51ais in contact with the right side of the ear portion58a1, i.e. in contact with the right inclined plane of the ear portion58a1facing the lowered part58a.

When the slider52starts to move in a main scanning direction in response to the drive of the motor59M in the second wiper drive, as serially shown inFIG. 4B,FIG. 4C, andFIG. 4D, the lower end51a1swings anticlockwise while contacting the right inclined plane of the ear portion58a1. This causes the sub wiper51to swing with the wiper supporter51aabout the shaft51bwhich extends along the sub-scanning directions, against the biasing force exerted by the biasing component, and hence the tilt angle of the sub wiper51with respect to the horizontal plane gets large (θ1inFIG. 48, θ2(>θ1) inFIG. 4C, and θ3(>θ2) inFIG. 4D). When the tilt angle shown inFIG. 4Dreaches θ3, the leading end of the sub wiper51contacts the outer surface8aof the conveyance belt8. As the sliders52further move in the main scanning direction, the ear portion58a1is pushed downward by the lower end51a1, with the result that the ear portion58a1takes the retracted position. As the sliders52further move in the main scanning direction, as shown inFIG. 4E, the lower end51a1passes through the space above the ear portion58a1. In this state, the sub wiper51and the wiper supporter51aare receiving the biasing force exerted by the biasing component (in the direction of changing the tilt angle of the sub wiper51from θ3to θ1). However, since the lower end51a1is supported by the surface of the plate58, the tilt angle of the sub wiper51is maintained at θ3. Then the sub wiper51moves in the main scanning direction while keeping its leading end to contact the outer surface8a. When the sub wiper51reaches the other end of the plate58in the main scanning directions, the lower end51a1faces the slope58b. In this state, as shown inFIG. 4F, the lower end51a1is distanced from the upper surface (slope58b) of the plate58. As such, the sub wiper51rotates clockwise about the shaft51btogether with the wiper supporter51aon account of the biasing force of the biasing component, with the result that the tilt angle of the sub wiper51returns from θ3to θ1and the leading end of the sub wiper51is distanced from the outer surface8aof the conveyance belt8.

After the second wiper drive, the sub wiper51moves to a position where its leading end contacts the sub wiper cleaner55a, while keeping the leading end to be distanced from the outer surface8aand maintaining the tilt angle at θ1. After the leading end of the sub wiper51is cleaned, by the sub wiper cleaner55a, as shown inFIG. 4G, the sub wiper51moves in the main scanning direction toward the home position while keeping the tilt angle at θ1. At around the home position, the lower end51a1contacts the left inclined plane of the ear portion58a1which does not face the lowered part58a, and passes through the ear portion58a1while changing the position of the ear portion58a1to the retracted position. Thereafter, the sub wiper51stops at the home position while maintaining its tilt angle at θ1and keeping its leading end to be distanced from the outer surface8a.

When the tilt angle is at θ3, the leading end part of the sub wiper51contacts and is warped by the outer surface8aof the conveyance belt8. The pressure of the sub wiper51onto the outer surface8aof the conveyance belt8when the tilt angle is at θ3is lower than the pressure of the main wiper41onto the outer surface8aduring the first wiper drive. In the present embodiment, the distance between the shaft51bwhich is the center of rotation of the sub wiper51and the outer surface8aof the conveyance belt8is longer than the distance between the shaft42which is the center of rotation of the main wiper41and the outer surface8aof the conveyance belt8. It is noted that the distance between the shaft51band the outer surface8aof the conveyance belt8may be identical with the distance between the shaft42and the outer surface8aof the conveyance belt8. In such a case, the tilt angle θ3of the sub wiper51during the second viper drive may be smaller than the tilt angle of the main wiper41during the first wiper drive.

Since the pressure of the sub wiper51is lower than the pressure of the main wiper41as described above, the wiping capability of the sub wiper51to wipe foreign matters from the outer surface8ais lower than the wiping capability of the main wiper41, and hence the frictional force between the sub wiper51and the outer surface8ais small during the second wiper drive. This restrains, in the second wiper drive, the conveyance belt8from being displaced in the main scanning directions on account of the movement of the sub wiper51in the main scanning directions. Since the displacement of the conveyance belt8in the main scanning directions is restrained, it is possible to restrain the deterioration of the conveying accuracy of the conveyance belt. Furthermore, the main wiper41exerting a high pressure certainly gathers, as described later, foreign matters to a small area, without allowing the sub wiper51exerting a low pressure to displace the conveyance belt8.

It is noted that, even if the pressure of the sub wiper51is small, a desired amount of foreign matters are removed from the outer surface8aof the conveyance belt8because the sub wiper51contacts the outer surface8a. In other words, removed by the sub wiper51are the foreign matters remaining at around the area of the outer surface8afrom which area the main wiper41has been detached and gathered to the small area by the main wiper41or the foreign matters adhering to the highly liquid repellent preliminary ejection region H, and few foreign matters remain after the wiping by the sub wiper51. This prevents the foreign matters remaining on the outer surface8aeven after the wiping of the sub wiper51from adhering to the back side of the sheet P conveyed by the conveyance belt8and prevents the attracting force of the conveyance belt8for attracting the sheet P from being lowered by the foreign matters adhering to the outer surface8a, thereby preventing the conveyance belt8from becoming unable to convey the sheet P.

The components (e.g. the belt54) by which the sub wiper51is moved in the main scanning directions are provided across the entire width of the conveyance belt8. The sub wiper51therefore moves, during the second wiper drive, from the one end to the other end of the conveyance belt8in the width direction while keeping the leading end part to contact and to be warped by the outer surface8aof the conveyance belt8, so as to remove the foreign matters across the entire width of the conveyance belt8. The foreign matters removed by the wipers41and51are received by an unillustrated receiver below the wipers41and51.

The capping mechanism70includes, as shown inFIG. 2A,FIG. 5A, andFIG. 5B, a annular component71circumscribing the four heads10and a moving mechanism72which vertically moves the annular component71. The annular component71circumscribes the four heads10and contacts the side faces of the assembly of the four heads11) only at around the upper end of the inner circumferential surface of the component71. The lower end of the annular component71is thrilled by an elastic material such as rubber.

The moving mechanism72includes two flanges71aand71bfixed to the side face of the annular component71, a guide75which slidably supports the flange71ain vertical directions, a shaft76having a male-threaded outer circumferential surface, and a motor77which rotates the shaft76under the control of the control unit1p. The guide75is fixed to the chassis1aand passes through a hole formed at the center of the flange71a. The shaft76is connected to the motor77fixed to the chassis1aand is screwed into a screw hole which is formed at the center of the flange71band has a female-threaded inner circumferential surface.

According to this arrangement, when the shaft76rotates forward under the control of the control unit1p, the annular component71moves from a retracted position (shown inFIG. 5A) where the lower end of the annular component71is distanced from the conveyance belt8to a contact position (shown inFIG. 5B) where the lower end of the annular component71contacts the outer surface8aof the conveyance belt8. The retracted position is a position where the ejection surfaces10a, the annular component71, and the outer surface8aof the conveyance belt8do not form a closed space and where the ejection surfaces10aare not covered by the annular component71and the outer surface8aof the conveyance belt8. On the other hand, the contact position is a position where the ejection surfaces10a, the annular component71, and the outer surface8aof the conveyance belt8form a closed space and where the ejection surfaces10aare covered by the annular component71and the outer surface8aof the conveyance belt8. At this position, since the upper end part of the annular component71contacts the side faces of the assembly of the four heads10, the ejection surfaces10a, the outer surface8aof the conveyance belt8, and the annular component71form a closed space. The four ejection surfaces10aare entirely covered by the annular component71and the outer surface8aof the conveyance belt8, i.e. these ejection surfaces10aare capped and sealed. This makes it possible to restrain the thickening of the ink around the ejection openings10bof the heads10. On the other hand, when the shaft76rotates backward under the control of the control unit1p, the annular component71moves from the contact position to the retracted position.

Now referring toFIG. 6andFIG. 7, the electric configuration of the printer1will be described. The control unit1pincludes, as shown inFIG. 6, a ROM (Read Only Memory)102, a RAM (Random Access Memory)103, an ASIC (Application Specific Integrated Circuit)104, an I/F (Interface)105, and an I/O port (Input/Output Port)106, in addition to a CPU (Central Processing Unit)101which is a processing unit. The ROM102stores programs executed by the CPU101and various types of data. The RAM103temporarily stores data (e.g. image data regarding an image to be printed on a sheet P) required for running a program. The ASIC104performs conversion of image data (e.g. signal processing and image processing). The I/F105performs data exchange with an external apparatus. The I/O port106is responsible for input and output of detection signals from/to various sensors.

The control unit1pis connected to the motors121,125,127,41M,45M,51M,59M, and77, the sheet sensor20, the power source36, and the control substrate of each head10. The control unit1phas, as shown inFIG. 7, functional parts such as a first wiping execution unit131, a second wiping execution unit132, a storage unit133, a recognition unit134, a capping control unit135, and a preliminary ejection control unit136, which are constructed by the above-described hardware.

The first wiping execution unit131controls the motor41M and the conveyance motor121to carry out the first wiper drive such that the leading end of the main wiper41distanced from the outer surface8ais moved to contact the outer surface8aand the main wiper41and the outer surface8aare relatively moved in the conveyance direction to wipe out the foreign matters on the outer surface8a. The first wiper drive of the present embodiment includes a preliminary wiping operation (first wiping operation) to wipe the outer surface8ato form a later-described first region G before the capping and a post wiping operation (second wiping operation) to wipe a later-described second region F during the capping.

The second wiping execution unit132controls the motor59M and the conveyance motor121to perform the second wiper drive such that the leading end of the sub wiper51distanced from the outer surface8ais moved to contact the outer surface8aand the sub wiper51and the outer surface8aare relatively moved in the main scanning direction to wipe the foreign matters on the outer surface8a.

The storage unit133stores the activity log of the printer1from the power on to the power off of the power source of the printer1. The activity log stored in the storage unit133is reset when a series of operations are carried out in response to a later-described maintenance instruction for the capping.

The recognition unit134recognizes the positions of the first region G and the second region F on the outer surface8a, based on the activity log stored in the storage unit133. In other words, based on the activity log, the recognition unit134recognizes, as the first region (3, a region which is not smaller in size than an enclosed range8b(seeFIG. 5B) of the outer surface8awhich range is enclosed by the annular component71at the contact position and is a region where an amount of adhering ink in an arbitrary range which is in the first region and is identical in size with the enclosed range is not larger than a predetermined amount. On the other hand, based on the activity log, the recognition unit134recognizes, as the second region F, a region which is not smaller in size than the enclosed, range8bof the outer surface8aand is a region where an amount of adhering ink in an arbitrary range which is in the second region and is identical in size with the enclosed range is larger than the predetermined amount. In regard to the first region G, it is assumed that an amount of adhering ink is not larger than the predetermined amount wherever in the first region G the selected arbitrary range identical in size with the enclosed range8bmight be. In the meanwhile, in the second region F, it is assumed that an amount of adhering ink is larger than the predetermined amount wherever in the second region F the selected arbitrary range identical in size with the enclosed range8bmight be.

For example, the activity log stored in the storage unit133indicates that an operation involving adherence of ink to the entirety of the outer surface8aof the conveyance belt8(e.g. a recording operation with which ink mist involving an adhering ink amount larger than the predetermined amount seems to occur, paper jam, and purging) has been carried out by the printer1, the recognition unit134recognizes that the predetermined amount or more of ink adheres to the entirety of the outer surface8aof the conveyance belt8. In short, the entirety of the outer surface8ais recognized as the second region F. It is noted that the case where a recording operation with which ink mist involving an adhering ink amount larger than the predetermined amount seems to occur has been carried out by the printer1corresponds to a case where the cumulative ink amount ejected from the heads10after a series of operations are carried out in response to the later-described maintenance instruction for the capping, i.e. after the wiping of the outer surface8a, exceeds a threshold. In this case, the recognition unit134recognizes that ink mist adheres to the entirety of the outer surface8aof the conveyance belt8and the amount of adhering ink exceeds the predetermined amount. When paper jam occurs, it is assumed that a large amount of ink adheres to the entirety of the outer surface8abecause ink is ejected from the head10even though no sheet P is conveyed. For this reason, the recognition unit134recognizes the entire surface as the second region F when paper jam occurs. In addition to the above, when purging (i.e. an operation to impart pressure to the ink in the heads10by driving the pump so as to eject the ink from all ejection openings) is carried out and a large amount of ink is ejected, it is also assumed in the same manner as the paper jam that a large amount of ink adheres to the entirety of the surface. For this reason, the entirety of the outer surface8ais recognized as the second region F, when purging is carried out. It is noted that the “predetermined amount” of adhering ink in the arbitrary range identical in size with the enclosed range may be arbitrarily determined as long as the amount is not zero. The “predetermined amount”, however, is preferably determined so that, when the ejection surfaces10aare entirely covered with the annular component71and the outer surface8a, the ink adhering to the outer surface8aabsorbs the moisture of the ink around the ejection openings10band hence the ink in the ejection openings10brapidly dries faster than a predetermined rate. In addition to the above, the recognition unit134recognizes the region wiped by the wiping mechanism60in the outer surface8aas the first region G. In other words, even after recognizing that the entirety of the outer surface8aof the conveyance belt8is the second region F, the recognition unit134further recognizes a region of the outer surface8awhich region has been wiped by the wiping mechanism60as the first region G, because an amount of ink remaining in that region is small.

When the activity log of the printer1indicates that preliminary ejection (i.e. an operation to cause the ejection openings10bto eject ink onto the preliminary ejection region H based on preliminary ejection data different from the image data) has been performed, the recognition unit134recognizes the preliminary ejection region H as the second region F and recognizes the region other than the region H as the first region G based on the activity log.

The capping control unit135controls the motor77of the moving mechanism72and the conveyance motor121of the conveying unit21to carry out the capping such that the first region G recognized by the recognition unit134contacts the annular component71and the ejection surfaces10aare entirely covered with the annular component71and the first region G. The capping control unit135performs the capping by controlling the moving mechanism72and moving the annular component71from the retracted position (indicated inFIG. 5A) to the contact position (indicated byFIG. 5B). The capping control unit135makes it possible to select one of provisional capping and definitive capping by controlling the moving mechanism72. The pressure of the annular component71onto the outer surface8aduring the provisional capping is lower than the pressure of the annular component71onto the outer surface8aduring the definitive capping. More specifically, the capping control unit135controls the moving mechanism72so that the position of the annular component71during the definitive capping is lower than the position during the provisional capping.

The preliminary ejection control unit136controls the heads10and the conveying unit21(conveyance motor121) so that ink is ejected from the ejection openings10bof the heads10to the preliminary ejection region H based on preliminary ejection data which is different from the image data which is supplied from an external apparatus. While the preliminary ejection is performed on the preliminary ejection region H in the present embodiment, the preliminary ejection may be performed on the entirety of the outer surface8a.

Now, referring toFIG. 8, the details of the maintenance carried out by the control unit1pwill be described. The steps below are executed by the CPU101based on programs stored in the ROM102.

First, the control unit1pdetermines, as shown inFIG. 8, whether a maintenance instruction for capping has been received (S1). The maintenance instruction is received, for example, in the following cases: after the power on of the printer1; when paper jam occurs after purging or preliminary ejection is carried out for the outer surface8aof the conveyance belt8; and when recording operations are not carried, out for a predetermined period.

If no maintenance instruction is received in S1(S1: NO), the control unit1pis kept on standby. If the maintenance instruction is received in S1(S1: YES), the control unit1pproceeds to S2. In S2, based on the activity log stored in the storage unit133, the recognition unit134recognizes whether the second region F exists on the outer surface8a. When the activity log stored in the storage unit133does not show an operation involving adherence of ink to at least a part of the outer surface8a(e.g. a recording operation with which ink mist involving an adhering ink amount larger than the predetermined amount seems to occur, paper jam, purging, and preliminary ejection) (S2: NO), the recognition unit134recognizes that the entirety of the outer surface8aof the conveyance belt8is the first region G, and the process proceeds to S10. On the other hand, when the activity log shows an operation involving adherence of ink to at least a part of the outer surface8a(S2: YES), the recognition unit134recognizes that the second region F corresponding to the operation exists on the outer surface8a, and the process proceeds to S3. When the activity log shows an operation involving adherence of ink to at least a part of the outer surface8a(e.g. a recording operation with which ink mist involving an adhering ink amount larger than the predetermined amount seems to occur, paper jam, and purging) (S2: YES), the recognition unit134recognizes that the entirety of the outer surface8ais the second region F and hence no first region G exists. In this case, on the outer surface8a, the later-described region wiped in the preliminary wiping operation is recognized as the first region G by the recognition unit134.

Subsequently, in S3, the control unit1pdetermines whether the entirety of the outer surface8ais the second region F, based on the activity log. When the entirety of the outer surface8ais the second region F (S3: YES), the process proceeds to S4. When only the preliminary ejection region H of the outer surface8ais recognized as the second region F (S3: NO), the process proceeds to S9. While the preliminary ejection is carried out only on the preliminary ejection region H in the present embodiment, the preliminary ejection may be carried out on the entirety of the outer surface8a. In such a case the process skips S3and proceeds to S4. On the other hand, when the ink ejected from the head by the purging adheres only to a particular region of the outer surface8a, the process proceeds to S9.

In S4, the control unit1pdrives the motor41M while the conveyance belt8being stopped, so as to rotate the main wiper41once clockwise inFIG. 1about the axis along the main scanning directions. During this rotation, the leading end of the main wiper41contacts and is warped by the circumferential surface of the wiper cleaner45. The foreign matters adhering to the leading end of the main wiper41are therefore transferred to the wiper cleaner45and removed therefrom (wiper cleaning).

The control unit1protates the wiper cleaner45for a predetermined angle smaller than 360 degrees, each time the wiper cleaning (S4) is completed once or several times. This causes the leading end of the main wiper41to contact a different part of the wiper cleaner45in the wiper cleaning, and hence the foreign matters adhering to the leading end of the main wiper41are effectively removed.

In S5, the first wiping execution unit131drives the motor41M so as to slightly rotate the main wiper41about the axis along the main scanning directions and causes the leading end of the main wiper41distanced from the outer surface8aof the conveyance belt8to contact the outer surface8a. When the leading end of the main wiper41contacts and is warped by the outer surface8a, the first wiping execution unit131stops the motor41M. The first wiping execution unit131then drives the conveyance motor121to cause the conveyance belt8to go around less than once. As such, the foreign matters on the outer surface8aof the conveyance belt8are gathered to a narrow range on the outer surface8aand removed by the main wiper41. More specifically, as shown inFIG. 9A, the conveyance belt8is moved while the main wiper41is in contact with the outer surface8a, with the result that the outer surface8ais wiped and the first region G is formed (preliminary wiping operation). It is noted that, inFIG. 9AtoFIG. 9C, only the second region F is hatched.

Subsequently, in S6, the capping control unit135stops the conveyance motor121when, as shown inFIG. 9B, the leading end of the first region G in the traveling direction faces the downstream end of the annular component71in the conveyance direction. The capping control unit135then controls the motor77so that the annular component71is moved from the retracted position to the contact position and the provisional capping starts. At the start of the provisional capping, as shown inFIG. 9B, a second region exists on the outer surface8aof the conveyance belt8, and the recognition unit134recognizes the existence of the second region.

Thereafter, in S7, the first wiping execution unit131drives the conveyance motor121again to move the conveyance belt8, and stops the conveyance motor121after the conveyance belt8goes around at least once including the movement for the preliminary wiping operation. As such, the conveyance belt8is moved while the capping is in action, and hence the leading end of the main wiper41contacts and is warped by the outer surface8awhereas the conveyance belt8goes around at least once. As a result, as shown inFIG. 9C, the entirety of the outer surface8abecomes the first region G. In other words, in S7the second region F which is not wiped in the preliminary wiping operation is wiped (post wiping operation). Therefore the entirety of the outer surface8ais wiped by the main wiper41, and hence ink is hardly stuck on the outer surface8a. Then the first wiping execution unit131drives the motor41M while the conveyance belt8being stopped, so as to slightly rotate the main wiper41about the axis along the main scanning directions and cause the leading end of the main wiper41to be distanced from the outer surface8a.

Thereafter, in S8, the second wiping execution unit132drives the conveyance motor121to move the conveyance belt8, and stops the conveyance motor121when the part of the outer surface8awhich part contacts the main wiper41at the very moment when the main wiper41is detached from the outer surface8aoverlaps the center of the sub wiper51in the sub-scanning directions. In this case, the region of the outer surface8afacing the annular component71is the first region G. Then the capping control unit135controls the motor77so that the pressure of the annular component71onto the outer surface8ais higher than the pressure during the provisional capping (i.e. the definitive capping starts). This improves the tightness concerning the ejection surfaces10aafter the post wiping operation. Furthermore, since the pressure onto the outer surface8aduring the provisional capping is lower than the pressure onto the outer surface8aduring the definitive capping, the frictional force between the outer surface8aand the annular component71is small when the conveyance belt8is moved while the provisional capping is conducted in the post wiping operation. This reduces the load caused by the travel of the conveyance belt8.

During the definitive capping, the second wiping execution unit132drives the motor59M forward. As a result, the leading end of the sub wiper51distanced from the outer surface8aof the conveyance belt8is moved to contact the outer surface8aand the sub wiper51is moved from the home position to the main scanning direction. Therefore the foreign matters on the outer surface8aof the conveyance belt8, i.e. the foreign matters remaining on the outer surface8aafter the main wiper41is detached therefrom are gathered to a narrow range and removed by the sub wiper51(second wiper drive). Therefore the ink hardly remains on the outer surface8a. Consequently, ink hardly adheres to the surface of the sheet P facing the outer surface8awhen the sheet P is conveyed on the outer surface8a, and hence the sheet P hardly gets dirty. In addition to the above, during the second wiper drive, the frictional force between the conveyance belt8and the annular component71is large due to the definitive capping. It is therefore possible to restrain the conveyance belt8from being displaced in the directions of the movement of the sub wiper51in the second wiper drive. The second wiping execution unit132temporarily stops the motor59M when the sub wiper51reaches the other end of the plate58in the main scanning directions. At this point, the leading end of the sub wiper51is distanced from the outer surface8a(seeFIG. 4F) and contacts the sub wiper cleaner55a. Thereafter, the second wiping execution unit132drives the motor59M backward to move the sub wiper51backward in the main scanning direction (i.e. in the direction in reverse to the direction of the movement (indicated by the arrow inFIG. 3) of the sub wiper51during the removal of the foreign matters) (seeFIG. 4G), and stops the motor59M when the sub wiper51reaches the home position. As a result, the first and second wiper drives are completed and the ejection surfaces10aare capped by the annular component71.

In the meanwhile, in S9, the second wiping execution unit132causes the conveyance belt8to move by driving the conveyance motor121, and stops the conveyance motor121when the center of the sub wiper51overlaps the center of the second region F (preliminary ejection region H) in the sub-scanning directions. At this point, since all regions of the conveyance belt8other than the preliminary ejection region H are the first region G, the region facing the annular component71is also the first region G. The capping control unit135then controls the motor77to move the annular component71from the retracted position to the contact position (i.e. the definitive capping starts). The motor77at this point is controlled so that the pressure of the annular component71onto the outer surface8ais identical with the pressure in the definitive capping in S8.

After the annular component71is moved to the contact position, i.e. during the definitive capping, the second wiping execution unit132drives the motor59M forward to perform the second wiper drive in the same manner as in S8, and temporarily stops the motor59M when the sub wiper51reaches the other end of the plate58in the main scanning directions. Thereafter, the second wiping execution unit132drives the motor59M backward to move the sub wiper51backward in the main scanning direction, and stops the motor59M when the sub wiper51reaches the home position. The second wiper drive is finished in this way, and the ejection surfaces10aare capped by the annular component71.

In S10, the capping control unit135controls the motor77so that an arbitrary position of the outer surface8acontacts the annular component71(i.e. the definitive capping starts). The motor77is controlled such that the pressure of the annular component71onto the outer surface8ais identical with the pressure in the definitive capping in S8. As such, the ejection surfaces10aare capped by the annular component71.

As described above, in the printer1of the present embodiment, only the predetermined amount or less ink adheres to the arbitrary range which is identical in size with the enclosed range8b, on the first region G of the outer surface8acovering the ejection surfaces10a. It is therefore possible to reduce the amount of thickened ink in the closed space formed by the capping, by performing the capping in such a way as to cause the first region G to contact the annular component71. It is therefore possible to restrain the progress of the drying of the ink in the ejection openings10b.

In S6, the provisional capping of the ejection surfaces10ais carried out even if the second region F exists on the outer surface8a. The capping control unit135can therefore perform the capping of the ejection surfaces10abefore the entirety of the outer surface8ais wiped by the main wiper41to eliminate the second region F on the outer surface8a. It is therefore possible to further restrain the drying of the ink in the ejection openings10b.

In S5, the outer surface8ais wiped before the capping so that the first region G is formed. As such, even if the entirety of the outer surface8ais the second region F, it is possible to easily form the first region G by wiping a part of the outer surface8aby the main wiper41. In the first region G which is formed by wiping a part of the outer surface8aby the main wiper41, the amount of adhering ink is smaller than the amount in the first region G which is not formed by wiping. For this reason, it is possible to further restrain the progress of the drying of the ink in the capped ejection openings10b, by setting the wiped region as the first region G.

In addition to the above, in S5to S7, the conveyance belt8goes around less than once in the preliminary wiping operation, and the provisional capping is performed after this preliminary wiping operation. The post wiping operation is then carried out during the provisional capping, and the ink not wiped in the preliminary wiping operation is wiped away from the outer surface8a. Since this arrangement shortens the time required for the preliminary wiping operation, the capping is carried out at an earlier timing. It is therefore possible to further restrain the drying of the ink in the ejection openings10b.

In addition to the above, the recognition unit134recognizes a region to which no ink is ejected by the preliminary ejection as the first region G and recognizes a preliminary ejection region H to which ink is ejected by the preliminary ejection and the ink is not wiped away as the second region F. The structure is therefore simplified in comparison with recognition means which recognizes the first region G and the second region F by actually measuring an amount of ink adhering to the outer surface8a. Furthermore, since the recognition unit134recognizes the position of the first region G (i.e. a region on the outer surface8awhich region is not the preliminary ejection region H) based on the activity log stored in the storage unit133, the structure of the recognition means is further simplified.

As a first variation, alternatively, when in S2the recognition unit134recognizes that no second region F exists on the outer surface8aand the entirety of the outer surface8ais recognized as the first region G, the process proceeds to S10, whereas J3and the subsequent steps are carried out as shown inFIG. 10when it is recognized that the second region F exists on the outer surface8a. In J3, the wiper cleaning is carried out in the same manner as S4above.

Subsequently, in J4, the first wiping execution unit131drives the motor41M to slightly rotate the main wiper41about the axis along the main scanning directions and causes the leading end of the main wiper41distanced from the outer surface8aof the conveyance belt8to contact the outer surface8a, and stops the motor41M when the leading end of the main wiper41contacts and is warped by the outer surface8a. After driving the conveyance motor121to cause the conveyance belt8to go round at least once, the first wiping execution unit131stops the conveyance motor121. As a result, the foreign matters on the entirety of the outer surface8aof the conveyance belt8are gathered to a narrow range on the outer surface8aand removed by the main wiper41. Consequently the first region G is formed on the entirety of the outer surface8a(first wiper drive). The first wiping execution unit131then drives the motor41M while the conveyance belt8being stopped, so as to slightly rotate the main wiper41about the axis along the main scanning directions and moves the leading end of the main wiper41away from the outer surface8a.

Subsequently, in J5, the second wiping execution unit132drives the conveyance motor121to move the conveyance belt8, and stops the conveyance motor121when a part of the outer surface8awhich part contacts the main wiper41at the very moment when the main wiper41is detached from the outer surface8aoverlaps the center of the sub wiper51in the sub-scanning directions. Since the entirety of the outer surface8ais the first region G at this point, the region facing the annular component71is also the first region G. The capping control unit135then controls the motor77so that the annular component71moves from the retracted position to the contact position (i.e. the definitive capping starts). The motor77is controlled so that the pressure of the annular component71onto the outer surface8ais identical with the pressure in the definitive capping in S8.

After the annular component71is moved to the contact position, i.e. during the definitive capping, the second wiping execution unit132drives the motor59M forward to perform the second wiper drive similar to that of S8, and temporarily stops the motor59M when the sub wiper51reaches the other end of the plate58in the main scanning directions. Thereafter, the second wiping execution unit132drives the motor59M backward to move the sub wiper51backward in the main scanning directions, and stops the motor59M when the sub wiper51reaches the home position. As such, the first and second wiper drives are finished and the ejection surfaces10aare capped by the annular component71.

Also in the first variation above, in the first region G of the outer surface8acovering the ejection surfaces10a, only the predetermined amount or less ink adheres to the arbitrary range identical in size with the enclosed range8b, and hence it is possible to restrain the progress of the drying of the ink in the capped ejection openings10b. Furthermore, since the entirety of the outer surface8ais wiped in J4, the entirety of the outer surface8abecomes the first region G and the capping can be carried out at an arbitrary position on the outer surface8a. Also, the control structure becomes simple. In addition to the above, ink hardly remains on the outer surface8aon account of the second wiper drive. Consequently; ink hardly adheres to the surface of the sheet P facing the outer surface8awhen the sheet P is conveyed on the outer surface8a, and hence the sheet P hardly gets dirty.

According to a second variation, the process proceeds to J3inFIG. 10when the condition in S3inFIG. 8is satisfied (S3: YES). In other words, the steps J3to J5similar to those in the first variation are carried out only when the entirety of the outer surface8ais the second region F. Effects similar to the above are achieved in this case. Also, the control structure becomes simple.

According to a third variation, when in S2shown inFIG. 8andFIG. 10the recognition unit134recognizes that no second region F exists on the outer surface8aand the entirety of the outer surface8ais the first region G, the process proceeds to S10. When the recognition unit134recognizes that there is a second region F on the outer surface8a, the process skips S3and proceeds to S4. Also in this case, it is possible to restrain the progress of the drying of the ink in the capped ejection openings10b, in the same manner as the embodiment above. Also, the control structure becomes simple.

According to another variation, there is recognition means which is arranged such that an image sensor having a detection surface facing the entire width of the outer surface8ais provided, the image sensor detects the first region G and the second region F on the outer surface8a, and a recognition unit134recognizes the positions of the first region G and second region F on the outer surface8abased on the detection signal. This arrangement improves the accuracy of the recognition of the first region G and the second region F on the outer surface8a.

In addition to the above, the wiping mechanism60may not be provided. In this case, based on the received maintenance instruction, the capping control unit controls the moving mechanism72and the conveying unit21so that the first region G recognized by the recognition unit134contacts the annular component71. In addition to the above, the wiping mechanism may have only one of the main wiping mechanism40and the sub wiping mechanism50. The main wiper41may extend in the directions orthogonal to both the main scanning directions and the sub-scanning directions. In addition to the above, the sub wiper51may extend in the directions orthogonal to both the main scanning directions and the sub-scanning directions. In addition to the above, in the second wiper drive, the sub wiper51may move in a direction orthogonal to both the main scanning directions and the sub-scanning directions. In addition to the above, in the first wiper drive, the main wiper41may be moved in the sub-scanning direction while either the conveyance belt8being stopped or the conveyance belt8being moved.

In addition to the above, recognition unit134may recognize only a position of the first region G on the outer surface8a. In short, the second region F may not be recognized. In addition to the above, the preliminary ejection control unit136may not be provided.

In addition to the above, the conveyance mechanism may have a rotational drum instead of the conveyance belt. The main and sub wipers may not be blade-shaped and may be variously shaped on condition that foreign matters on a surface of a conveyance component are removed by the relative movement of the leading end of the wiper with respect to the surface while the leading end contacts the surface.

The present invention may be used in all line-type and serial-type inkjet recording apparatuses. Also, the present invention may be used not only for printers but also for other apparatuses such as facsimile machines and photocopiers. The recording medium is not limited to sheets P but may be various recordable media.