JP6256376B2 - Inkjet recording device - Google Patents

Description

  The present invention relates to an ink jet recording apparatus.

  As a kind of image forming apparatus, an ink jet recording apparatus including a transport unit, a suction unit, and a recording head is known. The conveyance unit includes a conveyance belt, and conveys the sheet below the recording head by the conveyance belt. The suction unit sucks the sheet toward the conveyance belt. The recording head has nozzle holes, and ejects ink droplets from the nozzle holes toward the sheet conveyed below the recording head to record an image on the sheet. According to this type of ink jet recording apparatus, the recording speed can be improved by increasing the sheet conveying speed by the conveying belt.

  However, in the above-described ink jet recording apparatus, when a partially curled sheet is conveyed below the recording head, the curled portion of the sheet collides with the recording head, and a jam (sheet clogging) occurs. There is.

  Patent Document 1 describes an ink jet recording apparatus that solves this problem. Specifically, the ink jet recording apparatus described in Patent Document 1 suppresses the occurrence of jam due to sheet curl by making the suction force below the recording head larger than the suction force at other locations. .

  However, when the suction force below the recording head increases, the speed of the suction air generated below the recording head increases. For this reason, foreign matters such as paper dust adhering to the sheet rise and easily adhere to the nozzle holes. There is a possibility that ink droplets cannot be ejected from the nozzle holes to which foreign matter has adhered. Hereinafter, a nozzle hole that is unable to eject ink droplets is referred to as a non-ejection nozzle. When a non-ejection nozzle is generated, white stripes along the sheet conveyance direction are generated in an image recorded on the sheet. Therefore, the image quality is degraded.

JP 2004-18151 A

  By the way, the ink jet recording apparatus generally performs recording head maintenance whenever the total number of sheets on which images are recorded reaches a certain number. Specifically, the maintenance of the recording head is executed by a purge / wipe operation. By periodically performing the purge / wipe operation, the occurrence of a non-missing nozzle is suppressed. Accordingly, even when the suction force below the recording head is larger than the suction force at other locations, the interval between the maintenance timings of the recording head, that is, the interval between the execution timings of the purge / wipe operation, is set to a general inkjet recording apparatus. By making the length shorter than that, it is possible to suppress the occurrence of non-ejection nozzles.

  However, images cannot be recorded during maintenance of the recording head. For this reason, the processing speed (working efficiency) decreases when the interval between the maintenance periods of the recording head is shortened, that is, when the frequency of performing maintenance of the recording head is increased. In addition, the higher the frequency with which the print head maintenance is performed, the more ink is consumed for the purge operation.

  The present invention has been made in view of the above problems, and provides an ink jet recording apparatus capable of suppressing the frequency with which recording head maintenance is performed while suppressing the occurrence of jamming due to sheet curling. For the purpose.

  The ink jet recording apparatus of the present invention includes a conveyance belt, a suction unit, a recording head, a maintenance mechanism, a suction force control unit, a counting unit, and a maintenance control unit. The conveyance belt conveys a sheet. The suction unit generates a suction force to suck the sheet toward the conveyance belt. The recording head ejects ink droplets toward the sheet being conveyed by the conveyance belt. The maintenance mechanism performs maintenance of the recording head. The suction force control unit controls the suction force generated by the suction unit. The counting unit counts the total number of sheets transported by the transport belt according to the suction force. The maintenance control unit operates the maintenance mechanism when a result of counting by the counting unit exceeds a predetermined value.

  According to the present invention, it is possible to suppress the frequency with which the maintenance of the recording head is performed while suppressing the occurrence of a jam due to the curl of the sheet.

1 is a diagram illustrating a configuration of an ink jet recording apparatus according to a first embodiment of the present invention. It is the top view which looked at the 1st conveyance part and recording part shown in Drawing 1 from the upper part. It is the top view which looked at the 1st conveyance belt shown in Drawing 1 from the upper part. It is a figure which shows the structure of the 1st conveyance part and recording part which are shown in FIG. It is the top view which looked at the conveyance board shown in FIG. 4 from upper direction. (A) It is a top view of the groove | channel and through-hole which are shown in FIG. (B) It is sectional drawing of the groove | channel and through-hole along the AA line shown to Fig.6 (a). It is a figure which shows the structure of the ink supply mechanism which concerns on embodiment of this invention. It is a figure which shows operation | movement of the wiping unit which concerns on embodiment of this invention. It is a figure which shows operation | movement of the wipe blade which concerns on embodiment of this invention. It is a figure which shows the structure of the control part which concerns on 1st Embodiment of this invention. FIG. 6 is a diagram illustrating a relationship between a wind speed blown below a recording head and the number of ejection failure nozzles. It is a figure which shows the structure of the inkjet recording device which concerns on 2nd Embodiment of this invention. It is a figure which shows the structure of the curl amount measurement part shown in FIG. It is a figure which shows the structure of the control part which concerns on 2nd Embodiment of this invention. It is a figure which shows the structure of the curl amount measurement part which concerns on 3rd Embodiment of this invention. It is a figure which shows the structure of the control part which concerns on 3rd Embodiment of this invention.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. However, in the figures, the same or corresponding parts are denoted by the same reference numerals, and description thereof will not be repeated. In order to facilitate understanding, the drawings schematically show each component as a main component. In addition, numerical values, shapes, and the like shown in the following embodiments are examples and are not particularly limited.

[First Embodiment]
First, the configuration of the inkjet recording apparatus 1 according to the first embodiment will be described with reference to FIG. FIG. 1 is a diagram showing the configuration of the inkjet recording apparatus 1. Specifically, FIG. 1 shows the ink jet recording apparatus 1 at the time of recording an image on paper P (an example of a sheet). The ink jet recording apparatus 1 records an image on the paper P by ejecting ink droplets.

  The ink jet recording apparatus 1 includes an apparatus housing 100, a paper feeding unit 2, a first paper conveyance path 3, a first conveyance part 4, a recording unit 5, a second conveyance part 6, and a second paper conveyance path. 7, a branch member 8, a sheet reversing unit 9 (an example of a sheet reversing unit), a discharge tray 10, a wiping unit 11, and a control unit 12.

  The paper feed unit 2 feeds the paper P to the first paper transport path 3. The paper feed unit 2 includes a paper feed cassette 21 that is detachable from the apparatus housing 100. The paper feed unit 2 includes a paper feed roller 22. The paper feed roller 22 is disposed on one end side of the paper feed cassette 21.

  The paper feed cassette 21 can store a plurality of sheets of paper P. The paper feed roller 22 (pickup roller) takes out the paper P one by one from the paper feed cassette 21 and feeds it toward the first paper transport path 3.

  The first paper transport path 3 guides the paper P to the first transport unit 4. The ink jet recording apparatus 1 includes a plurality of transport roller pairs 31 provided along the first paper transport path 3. Further, the ink jet recording apparatus 1 includes a registration roller pair 32 provided at the most downstream location of the first paper transport path 3. The paper P fed from the paper feed unit 2 is sent toward the registration roller pair 32 by the first paper transport path 3 and the plurality of transport roller pairs 31.

  The registration roller pair 32 performs skew correction of the paper P. In addition, the registration roller pair 32 temporarily stops the sheet P in order to synchronize the recording timing of the image on the sheet P and the conveyance timing of the sheet P to the first conveying unit 4, and then performs image recording. The paper P is sent to the first transport unit 4 in accordance with the timing. More specifically, the sheet P comes into contact with the registration roller pair 32 and stops. The skew correction of the paper P is performed by this contact. Thereafter, the registration roller pair 32 sends the paper P toward the first transport unit 4 in accordance with the image recording timing.

  The first transport unit 4 is located immediately below the recording unit 5 when recording an image on the paper P. The first transport unit 4 transports the paper P sent from the registration roller pair 32 toward the second transport unit 6.

  The first transport unit 4 includes a first transport belt 410. The first conveyor belt 410 is an endless belt. The paper P sent out by the registration roller pair 32 is guided onto the first transport belt 410. The first transport unit 4 attracts the paper P to the first transport belt 410. As a result, the first transport belt 410 holds the paper P. The first transport unit 4 rotates the first transport belt 410 in a predetermined rotation direction (counterclockwise direction in FIG. 1). As the first transport belt 410 rotates, the paper P is transported in the direction indicated by the arrow X1 (sub-scanning direction). Hereinafter, the direction in which the paper P is transported by the first transport unit 4 (first transport belt 410) is referred to as a paper transport direction X1.

  The recording unit 5 records an image on the paper P by ejecting ink droplets toward the paper P being transported by the first transport unit 4. The recording unit 5 includes line heads 51Bk, 51C, 51M, and 51Y. The line head 51Bk ejects black ink droplets. The line head 51C discharges cyan ink droplets. The line head 51M ejects magenta ink droplets. The line head 51Y ejects yellow ink droplets. Since the line heads 51Bk, 51C, 51M, and 51Y have substantially the same configuration, they may be collectively referred to as the line head 51.

  The line head 51 records an image on the paper P by ejecting ink droplets toward the paper P while the first transport unit 4 (first transport belt 410) transports the paper P. Specifically, the line head 51 ejects ink droplets toward the paper P that passes through a position facing the line head 51. As a result, images such as characters and figures are recorded on the paper P.

  The second transport unit 6 transports the paper P sent from the first transport unit 4 toward the second paper transport path 7. The second transport unit 6 includes a second transport belt 610. The second conveyor belt 610 is an endless belt. The paper P sent out from the first transport unit 4 is guided onto the second transport belt 610. The second transport unit 6 attracts the paper P to the second transport belt 610. As a result, the second transport belt 610 holds the paper P. Further, the second transport unit 6 rotates the second transport belt 610 in a predetermined rotation direction (counterclockwise direction in FIG. 1). As the second transport belt 610 rotates, the paper P is transported toward the second paper transport path 7.

  The second paper transport path 7 guides the paper P toward the discharge port 101 formed in the apparatus housing 100. The inkjet recording apparatus 1 includes a plurality of conveyance roller pairs 71 provided along the second paper conveyance path 7. When the recording of the image on the paper P is completed, the paper P sent out from the second transport unit 6 is sent toward the discharge port 101 by the second paper transport path 7 and the plurality of transport roller pairs 71. The discharge port 101 is formed on one side surface (left side surface in FIG. 1) of the apparatus housing 100.

  The branch member 8 is provided in the middle of the path of the second paper transport path 7. The branch member 8 is rotatably supported. The conveyance destination of the paper P is switched between the discharge port 101 and the paper reversing unit 9 by the rotation of the branch member 8. Specifically, when images are recorded on both sides of the paper P, the paper P on which an image is recorded on one side is guided to the paper reversing unit 9.

  The paper reversing unit 9 reverses the transport direction of the paper P guided to the paper reversing unit 9 by the branch member 8. Specifically, the paper reversing unit 9 includes a plurality of transport roller pairs 91 for transporting the paper P. The paper reversing unit 9 includes a switchback unit 92 for reversing the conveyance direction of the paper P.

  First, the sheet reversing unit 9 sends the sheet P to the switchback unit 92. Next, the sheet reversing unit 9 sends the sheet P in the direction opposite to the direction in which the sheet P enters the switchback unit 92 and causes the sheet P to exit from the switchback unit 92. Thereby, the conveyance direction of the paper P is reversed. Thereafter, the sheet reversing unit 9 sends the sheet P after the conveyance direction is reversed to the first sheet conveyance path 3. In the present embodiment, the downstream end of the sheet reversing unit 9 joins the first sheet transport path 3 before the registration roller pair 32. According to such a configuration, after an image is recorded on the first surface of the paper P, the image can be recorded on the second surface of the paper P opposite to the first surface.

  The discharge tray 10 is fixed to one side surface (left side surface in FIG. 1) of the apparatus housing 100. The paper P discharged to the outside of the apparatus housing 100 through the discharge port 101 is placed on the discharge tray 10.

  The wiping unit 11 is positioned below the second transport unit 6 when an image is recorded on the paper P. The wiping unit 11 includes a plurality of wipe blades 111. The wipe blade 111 is a cleaning member for cleaning the nozzle surface 51 a of the line head 51. The nozzle surface 51 a of the line head 51 faces the first transport unit 4 (first transport belt 410) when an image is recorded on the paper P. A plurality of nozzle holes (not shown) for discharging ink droplets are formed in the nozzle surface 51a. The wiping unit 11 moves directly below the recording unit 5 when the wiping operation is performed, and wipes (wipes or wipes) the nozzle surface 51a with the wipe blade 111. Thereby, the nozzle surface 51a is cleaned.

  The control unit 12 has a memory 121. The memory 121 stores programs, setting information, and the like. The memory 121 is composed of a magnetic disk, a random access memory (RAM), a read only memory (ROM), and the like provided in an HDD (Hard Disk Drive). The control unit 12 controls the operation of each unit of the inkjet recording apparatus 1 by executing a program stored in advance in the memory 121.

  Next, the configuration of the line head 51 will be described with reference to FIG. FIG. 2 is a plan view of the first transport unit 4 and the recording unit 5 shown in FIG. 1 as viewed from above. As shown in FIG. 2, the line heads 51Bk, 51C, 51M, and 51Y are arranged in parallel from the upstream side to the downstream side in the paper transport direction X1 (leftward in FIG. 2).

  Each of the line heads 51Bk, 51C, 51M, and 51Y includes a first recording head 55a, a second recording head 55b, and a third recording head 55c. The first recording head 55a, the second recording head 55b, and the third recording head 55c are arranged in a staggered manner along a direction X2 orthogonal to the paper transport direction X1. Hereinafter, a direction X2 orthogonal to the paper transport direction X1 is referred to as a width direction X2. Further, the first recording head 55a, the second recording head 55b, and the third recording head 55c have substantially the same configuration, and may be collectively referred to as the recording head 55.

  The recording head 55 is formed with the nozzle surface 51a described with reference to FIG. The recording head 55 ejects ink droplets from the nozzle holes corresponding to the printing position onto the paper P transported by the first transport belt 410. As a result, images such as characters and figures are recorded on the paper P.

  Next, the first conveyor belt 410 will be described with reference to FIG. FIG. 3 is a plan view of the first conveyor belt 410 shown in FIG. 1 as viewed from above. As shown in FIG. 3, a plurality of suction holes 411 are formed in the first transport belt 410. The plurality of suction holes 411 are arranged along the paper transport direction X1 and the width direction X2. The plurality of suction holes 411 may be arranged in a staggered manner as shown in FIG.

  Next, the first transport unit 4 and the recording unit 5 will be described with reference to FIGS. FIG. 4 is a diagram illustrating the configuration of the first transport unit 4 and the recording unit 5 illustrated in FIG. 1. FIG. 4 shows a partial cross section of the first transport section 4 for easy understanding.

  The recording unit 5 further includes a head base 52 in addition to the line head 51 (recording head 55). The head base 52 supports each line head 51 (each recording head 55).

  The first transport unit 4 faces the line head 51 when an image is recorded on the paper P. The first transport unit 4 includes a drive roller 412, a belt speed detection roller 413, a tension roller 414, and a pair of guide rollers 415 disposed on the inner peripheral side of the first transport belt 410. The first transport unit 4 further includes a suction roller 416 disposed on the outer peripheral side of the first transport belt 410. The first transport unit 4 includes a transport plate 42 (an example of a guide member) and a suction unit 43.

  The first transport belt 410 is stretched around a drive roller 412, a belt speed detection roller 413, a tension roller 414, and a pair of guide rollers 415. The conveying plate 42 and the suction part 43 are arranged on the inner peripheral side of the stretched first conveying belt 410. The conveyance plate 42 faces the line head 51 via the first conveyance belt 410 when an image is recorded on the paper P. The suction unit 43 is disposed below the transport plate 42 on the inner peripheral side of the first transport belt 410.

  The drive roller 412 is disposed on the downstream side (left side in FIG. 4) of the transport plate 42 with respect to the paper transport direction X1. The drive roller 412 is rotationally driven by a motor (not shown), and rotates the first transport belt 410 in a predetermined rotation direction (counterclockwise direction in FIG. 4). As the first transport belt 410 rotates, the paper P is transported in the paper transport direction X1.

  The belt speed detection roller 413 is disposed on the upstream side (right side in FIG. 4) of the conveyance plate 42 with respect to the paper conveyance direction X1, and rotates due to friction generated between the belt conveyance detection roller 413 and the first conveyance belt 410. Preferably, the belt speed detection roller 413 and the driving roller 412 are arranged so as to maintain the flatness of the first conveyance belt 410 at a location facing the line head 51.

  The belt speed detection roller 413 includes a pulse plate (not shown), and the pulse plate rotates integrally with the belt speed detection roller 413. By measuring the rotational speed of the pulse plate, the rotational speed of the first conveyor belt 410 is detected.

  The tension roller 414 applies tension to the first transport belt 410 so that the first transport belt 410 does not bend. The pair of guide rollers 415 guides the first conveyor belt 410 so that the first conveyor belt 410 passes below the suction portion 43.

  The suction roller 416 is a driven roller. The suction roller 416 is opposed to the upstream end of the transport plate 42 in the paper transport direction X1 with the first transport belt 410 interposed therebetween. The suction roller 416 guides the paper P sent by the registration roller pair 32 (see FIG. 1) onto the first transport belt 410 and causes the first transport belt 410 to suck the paper P.

  The conveyance plate 42 supports the first conveyance belt 410 and supports the paper P via the first conveyance belt 410. The transport plate 42 guides the paper P transported by the first transport unit 4 (first transport belt 410) in the paper transport direction X1. The transport plate 42 has a plurality of grooves 421 arranged along the paper transport direction X1 and the width direction X2. Each groove 421 extends in the paper transport direction X1. Each groove 421 has an opening on the recording unit 5 side (first conveyance belt 410 side) and communicates with a suction hole 411 (see FIG. 3) of the first conveyance belt 410.

  Further, the transport plate 42 has a plurality of through holes 422 arranged along the paper transport direction X1 and the width direction X2. The plurality of through holes 422 are provided corresponding to the plurality of grooves 421, and the end surface of each through hole 422 on the recording unit 5 side (first conveyance belt 410 side) is the inner surface (bottom surface) of the corresponding groove 421. Is open. Accordingly, each through hole 422 communicates with the suction hole 411 of the first transport belt 410 via the corresponding groove 421. On the other hand, the end surface of each through hole 422 on the suction portion 43 side is open to the lower surface of the transport plate 42.

  The suction unit 43 generates a suction force to suck the paper P toward the first transport belt 410. Specifically, the suction unit 43 sucks air from the space above the first transport belt 410 through the grooves 421 and the through holes 422 of the transport plate 42 and the suction holes 411 of the first transport belt 410. By this suction, a wind (suction air) toward the suction unit 43 is generated in a space above the transport plate 42. When the paper P is guided onto the first transport belt 410 and covers a part of the first transport belt 410, a suction force (negative pressure) acts on the paper P, and the paper P is attracted to the first transport belt 410. The

  The suction part 43 includes a box-shaped member 431 whose upper surface is open, a suction device 432, and a duct 433. The conveyance plate 42 is disposed so as to cover the upper surface opening of the box-shaped member 431. A pressure chamber 434 is defined by the transport plate 42 and the box-shaped member 431. The pressure chamber 434 communicates with the suction hole 411 of the first transport belt 410 through the through hole 422 and the groove 421 of the transport plate 42.

  The suction device 432 is fixed to the lower surface of the box-shaped member 431. Specifically, an opening 435 is formed in the bottom wall of the box-shaped member 431. The suction device 432 is disposed corresponding to the opening 435. A duct 433 is connected to the suction device 432. The suction device 432 is a fan. However, the suction device 432 is not limited to a fan, and may be a vacuum pump, for example.

  When the suction device 432 is driven, a negative pressure is generated in the pressure chamber 434. Due to this negative pressure, a suction force is generated in the groove 421 through the through hole 422, and a suction force is generated in the suction hole 411 of the first conveying belt 410 through the groove 421. As a result, air is sucked into the pressure chamber 434 through the suction holes 411 of the first transport belt 410 and the grooves 421 and the through holes 422 of the transport plate 42. The air sucked into the pressure chamber 434 is exhausted through the suction device 432 and the duct 433. Further, when the paper P is guided onto the first conveying belt 410 and blocks a part of the plurality of suction holes 411, a suction force (negative pressure) is applied to the paper P from the suction holes 411 closed by the paper P. Acts to attract the paper P to the first transport belt 410.

  Subsequently, the conveyance plate 42 will be described with reference to FIGS. 5 and 6. FIG. 5 is a plan view of the transport plate 42 shown in FIG. 4 as viewed from above. Specifically, FIG. 5 shows a part of the surface 420 of the transport plate 42 on the line head 51 side. Hereinafter, the surface 420 on the line head 51 side of the transport plate 42 is referred to as a support surface 420. The transport plate 42 supports the paper P via the first transport belt 410 by the support surface 420.

  As shown in FIG. 5, a plurality of grooves 421 are formed on the support surface 420. Each groove 421 is a long groove that opens on the line head 51 side. Specifically, the shape of each groove 421 is an ellipse extending in the paper transport direction X1.

  The plurality of grooves 421 are arranged along the paper transport direction X1 and the width direction X2. The plurality of grooves 421 can be arranged in a staggered manner as shown in FIG. Specifically, the plurality of grooves 421 are arranged at positions that can face the suction holes 411 (see FIG. 3) of the first transport belt 410. That is, the plurality of grooves 421 are arranged at positions where they can communicate with the suction holes 411. With this arrangement, as the first conveying belt 410 advances (rotates), the suction holes 411 facing the grooves 421 are replaced one by one. Each groove 421 is formed so as to face at least two suction holes 411.

  Further, one through hole 422 is located in each groove 421. Each through hole 422 communicates with a corresponding groove 421. The plurality of through holes 422 may be arranged in a staggered manner as shown in FIG.

  6A is a plan view of the groove 421 and the through hole 422 shown in FIG. 4, and FIG. 6B is a plan view of the groove 421 and the through hole 422 along the line AA shown in FIG. FIG. As shown in FIG. 6B, the through hole 422 penetrates the transport plate 42 in the thickness direction, and one end of the through hole 422 opens into the corresponding groove 421.

  Next, an ink supply mechanism 500 that supplies ink to the recording head 55 will be described with reference to FIG. FIG. 7 is a diagram illustrating a configuration of the ink supply mechanism 500. Specifically, FIG. 7 shows an ink supply mechanism 500 corresponding to an arbitrary color. The ink jet recording apparatus 1 illustrated in FIG. 1 includes an ink supply mechanism 500 illustrated in FIG. 7 for each of black, cyan, magenta, and yellow colors.

  As shown in FIG. 7, the ink supply mechanism 500 includes an ink tank 501 and a pump mechanism 502. The ink supply mechanism 500 includes a first flow path 503 that connects the ink tank 501 and the pump mechanism 502, and a second flow path 504 that connects the pump mechanism 502 and the recording head 55. Further, the ink supply mechanism 500 includes a first electromagnetic valve 505 (an example of an inflow side switching valve) provided in the first flow path 503 and a second electromagnetic valve 506 (an example of an outflow side switching valve) provided in the second flow path 504. ).

  The second flow path 504 connects the pump mechanism 502 to each of the first recording head 55a, the second recording head 55b, and the third recording head 55c described with reference to FIG. However, in FIG. 7, for ease of understanding, any one of the first recording head 55a, the second recording head 55b, and the third recording head 55c is shown.

  The ink tank 501 stores ink 511 of any one color. In the present embodiment, the ink 511 is a water-based ink. For this reason, when an image is recorded on one side of the paper P, it is wetted by water contained in the ink, so that one side (image recording surface) of the paper P expands and a part of the paper P can curl. There is sex.

  The pump mechanism 502 includes a hollow cylinder 521 and a piston 522. A part of the piston 522 is inserted into the hollow part of the cylinder 521. The piston 522 can be moved in the longitudinal direction of the cylinder 521 by a driving device (not shown).

  One end of the first flow path 503 is connected to the ink tank 501, and the other end of the first flow path 503 is connected to the ink inlet formed at the bottom of the cylinder 521. One end of the second flow path 504 is connected to an ink outlet formed at the bottom of the cylinder 521, and the other end of the second flow path 504 is a fine flow path formed inside the recording head 55. 551 is connected to the inlet.

  The recording head 55 has a nozzle surface 51a, and a plurality of nozzle holes 51b arranged in the width direction X2 are formed in the nozzle surface 51a. Each nozzle hole 51 b communicates with the fine channel 551.

  When recording an image on the paper P, ink 511 is accommodated in the cylinder 521. Further, both the first electromagnetic valve 505 and the second electromagnetic valve 506 are opened, and the piston 522 is stopped at a preset position. When an ink droplet is ejected from the recording head 55 (nozzle hole 51b), the ink 511 is supplied from the cylinder 521 to the fine flow path 551 of the recording head 55 by a capillary phenomenon. When the ink 511 is stored in the cylinder 521, the piston 522 provided in the pump mechanism 502 performs a pulling operation in a state where the first electromagnetic valve 505 is opened and the second electromagnetic valve 506 is closed. As a result, the ink 511 stored in the ink tank 501 is drawn into the cylinder 521 included in the pump mechanism 502 via the first flow path 503.

  The ink supply mechanism 500 operates when the purge operation is performed. The operation of the ink supply mechanism 500 is controlled by the control unit 12 shown in FIG. When the purge operation is executed, the ink 511 is stored in the cylinder 521. Further, the first electromagnetic valve 505 is closed and the second electromagnetic valve 506 is opened, and the piston 522 performs a pushing operation. As a result, the ink 511 stored in the cylinder 521 is supplied to the fine flow path 551 via the second flow path 504, and the ink 511 (purge ink) is forcibly pushed out (purged) from the nozzle hole 51b. ) By this purging operation, bubbles, foreign matter such as thickened ink 511 and paper dust are pushed out of the recording head 55. Air bubbles, foreign matter such as thickened ink 511 and paper dust cause non-ejection nozzles.

  Next, the wiping unit 11 will be described with reference to FIGS. 8 and 9. FIG. 8 is a diagram illustrating the operation of the wiping unit 11. The operation of the wiping unit 11 is controlled by the control unit 12 shown in FIG.

  As shown in FIG. 8, the wiping unit 11 moves directly below the line head 51 when the wiping operation is performed. The wiping unit 11 includes three wipe blades 111 for each of the line heads 51Bk, 51C, 51M, and 51Y. The three wipe blades 111 are arranged so as to correspond to the first recording head 55a, the second recording head 55b, and the third recording head 55c described with reference to FIG.

  FIG. 9 is a diagram illustrating the operation of the wipe blade 111. The operation of the wipe blade 111 is controlled by the control unit 12 shown in FIG. During maintenance of the line head 51 (recording head), the purge operation described with reference to FIG. 7 is first performed. As a result, as shown in FIG. 9A, a part of the purge ink 511a pushed out from the nozzle hole 51b of the recording head 55 remains on the nozzle surface 51a. Thereafter, a wiping operation is performed.

  When the wipe operation is executed, the wipe blade 111 is pressed against the nozzle surface 51a of the recording head 55 as shown in FIG. Specifically, the corresponding wipe blade 111 is pressed against one end (the right end in FIG. 9) of the nozzle surface 51a in the width direction X2. Next, as shown in FIGS. 9A and 9B, the wipe blade 111 moves in the direction indicated by the arrow D1 (leftward in FIG. 9) while being pressed against the nozzle surface 51a. With this movement of the wipe blade 111, the purge ink 511a remaining on the nozzle surface 51a is wiped off by the wipe blade 111 and flows down along the wipe blade 111 from the nozzle surface 51a.

  Next, the controller 12 shown in FIG. 1 will be described with reference to FIG. FIG. 10 is a diagram illustrating a configuration of the control unit 12 according to the first embodiment. As illustrated in FIG. 10, the control unit 12 includes a suction force control unit 122, a curl amount calculation unit 123 a, a counting unit 124, and a maintenance control unit 125 by executing a program stored in advance in the memory 121. To work.

  The suction force control unit 122 controls the suction force generated by the suction unit 43 described with reference to FIG. Specifically, the paper P stored in the paper feed cassette 21 shown in FIG. 1 may be curled, and the predicted range of the curl amount (curl amount) is shown in the product specification of the paper P. . The suction force control unit 122 changes the suction force generated by the suction unit 43 according to the maximum value of the curled amount prediction range. Thereby, even if the paper P fed from the paper feed cassette 21 is curled, the paper P can be reliably attracted to the first transport belt 410 shown in FIG.

  In the present embodiment, the suction force control unit 122 controls the operation of the suction device 432 described with reference to FIG. The suction device 432 in the present embodiment is a fan. Therefore, the suction force can be controlled, for example, by controlling the rotational speed of the fan.

  In the present embodiment, the memory 121 stores the first table 126. The first table 126 defines the suction force corresponding to the maximum value of the curl amount prediction range for each paper P that can be stored in the paper feed cassette 21. That is, the first table 126 is capable of attracting the paper P to the first transport belt 410 even when the curl amount of the paper P stored in the paper feed cassette 21 is the maximum value in the predicted range. Force is set. The suction force control unit 122 determines the suction force with reference to information specifying the paper P fed from the paper feed cassette 21 and the first table 126.

  Even if the curl amount is the same, if the paper type (material), basis weight (mass per unit area), or size of the paper P is different, the stiffness (stiffness, waist) of the paper P is different. The suction force necessary to reliably attract the paper P to the transport belt 410 is also different. Therefore, the first table 126 is preferably set to a value obtained by correcting the suction force according to the curled amount prediction range based on at least one of the paper type, basis weight, and size of the paper P. The As a result, the paper P can be more reliably attracted to the first transport belt 410. Therefore, it is possible to further suppress the occurrence of jam.

  Further, when the suction force below the recording head 55 increases, the speed of the suction air generated below the recording head 55 increases. For this reason, foreign substances such as paper dust adhering to the paper P rise and easily adhere to the nozzle holes. As a result, non-ejection nozzles are likely to occur. Therefore, the suction force set in the first table 126 is set to the lowest suction force (lower limit value of the suction force) among the suction forces that can reliably attract the paper P to the first transport belt 410. preferable. Thereby, generation | occurrence | production of a non-ejection nozzle can be suppressed.

  Next, the suction force generated by the suction unit 43 when images are recorded on both sides of the paper P will be described. As described with reference to FIG. 7, in this embodiment, since the ink 511 is a water-based ink, when an image is recorded on one surface (first surface) of the paper P, the ink is wetted by the water contained in the ink. As a result, one surface of the paper P may expand, and a part of the paper P may curl. Therefore, when images are recorded on both sides of the paper P, after an image is recorded on the first side of the paper P, the image is recorded on the second side of the paper P opposite to the first side. Then, the curled portion of the paper P may collide with the recording head 55 to cause a jam.

  In order to solve this problem, the suction force control unit 122 of the present embodiment is configured such that the suction unit 43 is used when the first transport belt 410 transports the paper P whose transport direction has been reversed by the paper reversing unit 9. The suction force generated by the is changed. Specifically, the suction force control unit 122 is generated by the suction unit 43 when an image is recorded on the second surface of the paper P after the image is recorded on the first surface of the paper P. The suction force is set larger than the suction force generated by the suction unit 43 when the image is recorded on the first surface of the paper P. Thus, even when the first surface of the paper P is expanded and a part of the paper P is curled, the paper P is reliably placed on the first conveying belt 410 when an image is recorded on the second surface of the paper P. It is possible to suppress the occurrence of jam by adsorbing.

  Further, the amount of curl (curl amount) generated due to the image recording on the first surface of the paper P can be calculated based on the printing rate of the image recorded on the first surface of the paper P. . In the first embodiment, the curl amount calculation unit 123a illustrated in FIG. 10 calculates the amount of curl (curl amount) generated due to the image recording on the first surface of the paper P.

  That is, the curl amount calculation unit 123a first calculates the printing rate of the image recorded on the first surface of the paper P. Next, the curl amount calculation unit 123a calculates the curl amount based on the printing rate. The curl amount increases in proportion to the printing rate of the image recorded on the first surface of the paper P. That is, the curl amount increases as the printing rate increases. Therefore, the curl amount can be calculated based on the printing rate of the image recorded on the first surface of the paper P. The printing rate is calculated by counting the number of dots of the image recorded on the first surface of the paper P and dividing the counted result by the size of the paper P.

  Furthermore, the curl amount calculation unit 123a according to the present embodiment weights the number of dots at the edge of the paper P when counting the number of dots of the image recorded on the first surface of the paper P. Count the number of dots. That is, when the image pattern of the image recorded on the first surface of the paper P includes an image recorded on the edge of the paper P, the paper P is likely to be curled. Therefore, when the printing rate is calculated, a more accurate curl amount can be calculated by weighting the number of dots at the edge of the paper P. Note that curl is likely to occur at the four corners of the paper P, and is largest at the four corners of the paper P. Therefore, weighting may be applied only to the number of dots at the four corners of the paper P.

  Further, when counting the number of dots of an image recorded on the first surface of the paper P, the curl amount calculation unit 123a performs weighting according to the print quality setting and counts the number of dots. That is, as the print quality setting is higher, the maximum density of the image is set higher, so that the ink discharge amount increases and the curl amount increases. Therefore, a more accurate curl amount can be calculated by weighting according to the print quality setting (density) when calculating the printing rate.

  Even if the printing rate is the same, if the paper type, basis weight, or size of the paper P is different, the rigidity of the paper P is different, and this occurs due to the image recording on the first surface of the paper P. The amount of curling (curling amount) is also different. The curl amount calculation unit 123a of the present embodiment acquires at least one of the paper type, basis weight, and size of the paper P from the information for specifying the paper P. Then, the curl amount calculation unit 123a corrects the curl amount calculated based on the printing rate in accordance with at least one of the paper type, basis weight, and size of the paper P. Thereby, a more accurate curl amount can be calculated.

  The shape of the paper conveyance path that guides the paper P delivered from the second conveyance unit 6 to the first conveyance unit 4 may affect the curl amount. For example, when the paper conveyance path includes a bent portion with a small curvature, the bent portion easily causes curling. Therefore, the curl amount calculated based on the printing rate may be corrected according to the shape of the paper transport path. Thereby, a more accurate curl amount can be calculated.

  On the other hand, the memory 121 stores a second table 127 in which a suction force is defined for each curl amount. The suction force control unit 122 determines the suction force by referring to the curl amount calculated by the curl amount calculation unit 123a and the second table 127. In the second table 127, for each curl amount, a suction force that can reliably attract the paper P to the first conveyance belt 410 is set even if the curl amount is curled.

  According to this embodiment, the suction force control unit 122 generates the suction unit 43 according to the amount of curl (curl amount) generated on the paper P due to the recording of the image on the first surface of the paper P. Change the suction force. As a result, even if one surface (first surface) of the paper P expands and the paper P is curled, the paper P is placed on the first conveying belt 410 when an image is recorded on the second surface of the paper P. Adsorption can be ensured. Therefore, the occurrence of jam can be suppressed.

  Even if the curl amount is the same, if the paper type, basis weight, or size of the paper P is different, the stiffness of the paper P is different, so that it is necessary to securely attract the paper P to the first conveying belt 410. The suction force is also different. Therefore, the memory 121 may store the second table 127 for each paper type, basis weight, or size of the paper P. Alternatively, the memory 121 may store the second table 127 for each combination of at least two of the paper type, basis weight, and size of the paper P. This makes it possible to more reliably attract the paper P to the first transport belt 410 when recording an image on the second surface of the paper P. Therefore, it is possible to further suppress the occurrence of jam.

  Further, the suction force set in the second table 127 is the lowest among the suction forces that can reliably attract the paper P to the first transport belt 410, similarly to the suction force set in the first table 126. The suction force (lower limit of suction force) is preferable. Thereby, generation | occurrence | production of a non-ejection nozzle can be suppressed.

  Next, the timing for starting maintenance of the line head 51 (recording head 55) will be described. In the inkjet recording apparatus 1 of the present embodiment, the maintenance mechanism of the line head 51 includes the ink supply mechanism 500 described with reference to FIG. 7 and the wiping unit 11 described with reference to FIGS. 1, 8, and 9. Including. When the maintenance mechanism of the line head 51 is activated, a purge operation is first executed, and then a wipe operation is executed.

  FIG. 11 is a diagram illustrating the relationship between the wind speed of the wind (suction air) blown below the recording head 55 and the number of non-ejection nozzle generations. In FIG. 11, the horizontal axis indicates the wind speed (m / sec) of the wind blown below the recording head 55. The vertical axis indicates the number of ejection failure nozzles. The non-ejection nozzle generation start number indicates how many sheets P of non-ejection nozzles have started to be generated when images are recorded on a plurality of sheets P.

  As shown in FIG. 11, the value of the non-ejection nozzle generation start number decreases as the suction wind speed increases. That is, as the suction force generated by the suction unit 43 increases, non-ejection nozzles are more likely to occur with a smaller number of sheets. On the other hand, in this embodiment, for example, when images are recorded on both sides of the paper P, the suction force control unit 122 changes the suction force generated by the suction unit 43. Therefore, in the present embodiment, the counting unit 124 illustrated in FIG. 10 counts the total number of sheets P transported by the first transport belt 410 according to the suction force generated by the suction unit 43.

  The coefficient used for weighting is set based on the relationship (relationship shown in FIG. 11) between the wind speed of the wind (suction air) blown below the recording head 55 and the number of non-ejection nozzle generations. In other words, the coefficient used for weighting is set based on the relationship between the suction force generated by the suction unit 43 and the number of non-ejection nozzle generation start. As a result, even if the suction force changes, it is possible to determine whether or not the total number of sheets P conveyed by the first conveyance belt 410 has reached the non-ejection nozzle generation start number. That is, it is possible to determine whether or not the time when the non-ejection nozzle occurs has arrived.

  In the present embodiment, the maintenance control unit 125 illustrated in FIG. 10 determines whether the count result (count value) by the count unit 124 has reached a threshold value (predetermined value). Further, when the count value exceeds the threshold value, the maintenance control unit 125 activates the maintenance mechanism of the line head 51 (recording head 55). On the other hand, the counting unit 124 initializes the count value when the maintenance mechanism of the line head 51 is activated.

  The threshold value that defines the maintenance start timing of the line head 51 is set so that the maintenance of the line head 51 is started before the timing at which a non-ejection nozzle starts to be generated. Note that an arbitrary threshold can be set as long as the maintenance of the line head 51 is started before the time when the non-ejection nozzle starts to be generated. For example, as the threshold value is decreased, the certainty that white streaks due to non-ejection nozzles can be prevented increases. On the other hand, when the threshold value is increased, it is possible to reduce the consumption of ink used for the purge operation and improve the processing speed (working efficiency). Therefore, when priority is given to image quality, a smaller threshold is set. When priority is given to ink consumption and processing speed, a larger threshold is set.

[Second Embodiment]
Next, a second embodiment will be described with reference to FIGS. However, items different from the first embodiment will be described, and descriptions of the same items as the first embodiment will be omitted. The second embodiment differs from the first embodiment in that the curl amount measurement unit 13 measures the curl amount of the paper P.

  FIG. 12 is a diagram illustrating a configuration of the inkjet recording apparatus 1 according to the second embodiment. As shown in FIG. 12, the ink jet recording apparatus 1 according to the second embodiment includes a curl amount measurement unit 13.

  The curl amount measurement unit 13 is provided in the paper reversing unit 9 and measures the curl amount of the paper P after the conveyance direction is reversed by the paper reversing unit 9. Specifically, the curl amount measurement unit 13 is provided below the portion of the transport path of the paper reversing unit 9 where the paper P is transported in the horizontal direction. Further, the curl is likely to occur at the four corners of the paper P, and becomes the largest at the four corners of the paper P. Therefore, the curl amount measurement unit 13 is preferably arranged at a position where the curl amounts at the four corners of the paper P can be measured.

  FIG. 13 is a diagram illustrating a configuration of the curl amount measurement unit 13 illustrated in FIG. Specifically, FIG. 13A shows the operation of the curl amount measurement unit 13 when measuring the curl amount of the front end portion of the paper P. FIG. 13B shows the operation of the curl amount measurement unit 13 when measuring the curl amount of the trailing edge of the paper P. An arrow X3 shown in FIG. 13 indicates the transport direction of the paper P.

  As shown in FIG. 13, the curl amount measuring unit 13 includes a light emitting unit 131, a first light receiving unit 132, and a second light receiving unit 133. The light emitting unit 131 emits the light L1 toward the paper P. For the light emitting unit 131, an LED (Light Emitting Diode) can be used. The first light receiving unit 132 and the second light receiving unit 133 receive the reflected light L2 reflected from the paper P. A charge coupled device (CCD) may be used for the first light receiving unit 132 and the second light receiving unit 133.

  As shown in FIG. 13A, when the front end portion of the paper P is curled, the reflected light L <b> 2 reflected from the paper P is received by the first light receiving unit 132. The first light receiving unit 132 outputs a signal corresponding to the incident position of the reflected light L2. Specifically, the signal output from the first light receiving unit 132 indicates the position where the reflected light L2 is incident on the first light receiving unit 132. The position where the reflected light L <b> 2 is incident on the first light receiving portion 132 changes according to the curl amount of the front end portion of the paper P.

  As shown in FIG. 13B, when the rear end portion of the paper P is curled, the reflected light L2 reflected from the paper P is received by the second light receiving unit 133. The second light receiving unit 133 outputs a signal corresponding to the incident position of the reflected light L2. Specifically, the signal output from the second light receiving unit 133 indicates the position where the reflected light L2 is incident on the second light receiving unit 133. The position where the reflected light L <b> 2 is incident on the second light receiving unit 133 changes according to the curl amount at the rear end of the paper P.

  The curl amount measuring unit 13 may include a condensing lens disposed above the light emitting unit 131, the first light receiving unit 132, and the second light receiving unit 133, respectively. By arranging the condensing lens above the light emitting unit 131, the light L1 emitted from the light emitting unit 131 is condensed on the paper P by the condensing lens. As a result, the image of the reflected light L2 received by the first light receiving unit 132 and the second light receiving unit 133 is less likely to become a blurred image, so that a more accurate curl amount can be calculated. In addition, since the condensing lens is disposed above the first light receiving unit 132, the reflected light L2 reflected from the paper P is condensed on the first light receiving unit 132 by the condensing lens. As a result, the image of the reflected light L2 received by the first light receiving unit 132 is less likely to be a blurred image, and thus a more accurate curl amount can be calculated. Similarly, by arranging the condensing lens above the second light receiving unit 133, the reflected light L2 reflected from the paper P is condensed on the second light receiving unit 133 by the condensing lens. As a result, since the image of the reflected light L2 received by the second light receiving unit 133 is less likely to be a blurred image, a more accurate curl amount can be calculated.

  FIG. 14 is a diagram illustrating a configuration of the control unit 12 according to the second embodiment. The control unit 12 according to the second embodiment includes a suction force control unit 122, a curl amount calculation unit 123b, a counting unit 124, and a maintenance control unit 125 by executing a program stored in the memory 121 in advance. Function. In the control unit 12 of the second embodiment, the curl amount calculation unit 123b is based on a signal output from the curl amount measurement unit 13 (the first light receiving unit 132 and the second light receiving unit 133) illustrated in FIG. The amount of curl is calculated.

[Third Embodiment]
Next, a third embodiment will be described with reference to FIGS. 15 and 16. However, matters different from the first embodiment and the second embodiment will be described, and descriptions of the same matters as the first embodiment and the second embodiment will be omitted. The third embodiment differs from the second embodiment in the configuration of the curl amount measurement unit 13. The curl amount measuring unit 13 according to the third embodiment is provided in the paper reversing unit 9 in the same manner as the curl amount measuring unit 13 according to the second embodiment.

  FIG. 15 is a diagram illustrating a curl amount measurement unit 13 according to the third embodiment. Specifically, FIG. 15A shows a state of the curl amount measurement unit 13 when the paper P is not curled. FIG. 15B shows the operation of the curl amount measuring unit 13 when measuring the curl amount of the front end portion of the paper P. FIG. 15C shows the operation of the curl amount measurement unit 13 when measuring the curl amount of the trailing edge of the paper P. An arrow X3 shown in FIG. 15 indicates the transport direction of the paper P.

  The curl amount measurement unit 13 according to the third embodiment includes a detection piece 135 and an inclination angle detector 136. As shown in FIG. 15, the curl amount measurement unit 13 does not contact the detection piece 135 when the paper P is not curled, and the front end of the detection piece 135 when the paper P is curled. The sheet P is disposed at a position where the sheet P collides with the part.

  The detection piece 135 has a long axis. The detection piece 135 is rotatably supported by an inclination angle detector 136. Further, the inclination angle detector 136 returns the detection piece 135 to a vertically upward posture as shown in FIG. 15A after the curled paper P collides with the detection piece 135 and the detection piece 135 is inclined. Thus, the detection piece 135 is urged.

  The tilt angle detector 136 outputs a signal indicating the tilt angle of the detection piece 135. In the present embodiment, when the posture of the detection piece 135 is a vertically upward posture as shown in FIG. 15A, the inclination angle detector 136 indicates that the inclination angle of the detection piece 135 is 0 °. The signal shown is output. In this case, the greater the curl amount of the paper P, the greater the tilt angle indicated by the signal output from the tilt angle detector 136.

  FIG. 16 is a diagram illustrating a configuration of the control unit 12 according to the third embodiment. The control unit 12 according to the third embodiment includes a suction force control unit 122, a curl amount calculation unit 123c, a counting unit 124, and a maintenance control unit 125 by executing a program stored in advance in the memory 121. Function. In the control unit 12 of the third embodiment, the curl amount calculation unit 123c calculates the curl amount of the paper P based on a signal output from the curl amount measurement unit 13 (tilt angle detector 136) illustrated in FIG. .

  Note that, in the present embodiment, the form in which the curl amount measurement unit 13 outputs a signal indicating the tilt angle of the detection piece 135 has been described. However, the present invention is not limited to this. The curl amount measurement unit 13 may output a signal indicating whether or not the detection piece 135 is tilted. In this case, in the control unit 12, the function of the curl amount calculation unit 123c can be omitted. In this case, the suction force control unit 122 determines whether or not to change the suction force generated by the suction unit 43 according to whether or not the detection piece 135 is tilted. That is, when the paper P is curled, the suction force control unit 122 causes the suction unit 43 to generate the image on the first surface of the paper P when the image is recorded on the second surface of the paper P. A predetermined suction force larger than the suction force is generated in the suction portion 43. On the other hand, when the paper P is not curled, the suction force control unit 122 causes the suction unit 43 to generate the image on the first surface of the paper P when the image is recorded on the second surface of the paper P. The suction unit 43 generates the same suction force as the suction force.

  As described above, according to the embodiment of the present invention, it is possible to suppress the occurrence of jam due to the curling of the paper P. Further, the suction force generated by the suction unit 43 is adjusted according to the curl amount of the paper P. Further, the maintenance start timing of the line head 51 (recording head 55) is adjusted according to the suction force generated by the suction unit 43. Therefore, the frequency at which the maintenance of the line head 51 is performed can be suppressed as compared with the case where the purge / wipe operation is periodically performed. Therefore, the processing speed can be improved as compared with the case where the purge / wipe operation is periodically executed. In addition, the consumption of ink used for the purge operation can be suppressed.

  Further, when the purge / wipe operation is periodically performed, there is a possibility that a non-ejection nozzle may be generated before the purge / wipe operation is performed. On the other hand, according to the embodiment of the present invention, the total number of sheets P transported by the first transport belt 410 is weighted and counted according to the suction force generated by the suction unit 43. As a result, generation of non-ejection nozzles can be suppressed as compared with the case where the purge / wipe operation is periodically executed.

  The embodiments of the present invention have been described above with reference to the drawings. However, the present invention is not limited to the above-described embodiment, and can be implemented in various modes without departing from the gist thereof.

  For example, in the embodiment of the present invention, the curl amount calculation unit 123a calculates the curl amount by counting the number of dots of the entire image recorded on the first surface of the paper P, but the present invention is not limited to this. . For example, the curl amount calculation unit 123a may count only the number of dots at the end or four corners of the paper P to calculate the curl amount at the end or four corners of the paper P. Alternatively, the curl amount calculation unit 123a may calculate the curl amount based only on the density of the image recorded on the first surface of the paper P.

  In the embodiment of the present invention, the suction force is changed according to the calculated curl amount, but the present invention is not limited to this. For example, the suction force may be changed according to only the print quality setting.

  In the embodiment of the present invention, the line head 51 configured by the three recording heads 55 has been described as an example, but the present invention is not limited to this. The line head 51 can be configured by one, two, or four or more recording heads.

  In the embodiments of the present invention, the case where the present invention is applied to an inkjet recording apparatus capable of recording an image in full color has been described. However, the present invention can also be applied to an inkjet recording apparatus that records an image in monochrome. .

  Note that the items described in the embodiment of the present invention can be combined as appropriate.

  The present invention can be used in an electronic apparatus capable of recording an image on a sheet by discharging ink droplets.

DESCRIPTION OF SYMBOLS 1 Inkjet recording device 4 1st conveyance part 5 Recording part 9 Paper reversing part 11 Wiping unit 12 Control part 43 Suction part 51, 51Bk, 51C, 51M, 51Y Line head 55, 55a-55c Recording head 111 Wipe blade 122 Suction force control Units 123a to 123c curl amount calculating unit 124 counting unit 125 maintenance control unit 410 transport belt 500 ink supply mechanism P paper

Claims (10)

A conveyor belt for conveying the sheet;
A suction unit that generates a suction force and sucks the sheet toward the transport belt;
A recording head that ejects ink droplets toward the sheet being conveyed by the conveying belt;
A maintenance mechanism for performing maintenance of the recording head;
A suction force control unit for controlling the suction force generated by the suction unit;
A counting unit for weighting and counting the total number of sheets conveyed by the conveyance belt according to the suction force;
An inkjet recording apparatus comprising: a maintenance control unit that activates the maintenance mechanism when a result of counting by the counting unit exceeds a predetermined value.   The inkjet recording apparatus according to claim 1, wherein the suction force control unit changes the suction force according to a curl amount of the sheet. A curl amount calculating unit for calculating the curl amount of the sheet;
The inkjet recording apparatus according to claim 2, wherein the suction force control unit changes the suction force according to the curl amount calculated by the curl amount calculation unit.   The inkjet recording apparatus according to claim 3, wherein the curl amount calculation unit calculates a curl amount of the sheet based on a printing rate of an image to be recorded on the sheet.   The curl amount calculation unit calculates the curl amount of the sheet based on a print rate of an image to be recorded on the sheet and at least one of an image pattern of the image and a print quality setting. Inkjet recording apparatus.   The curl amount calculation unit, after calculating the curl amount of the sheet, corrects the calculated curl amount based on at least one of the material, mass per unit area, and size of the sheet. The inkjet recording device according to any one of claims 3 to 5. A curl amount measuring unit for measuring the curl amount of the sheet;
The inkjet recording apparatus according to claim 2, wherein the suction force control unit changes the suction force according to a curl amount measured by the curl amount measurement unit.   The suction force control unit determines the suction force according to the curl amount of the sheet, and then determines the suction determined based on at least one of the material, mass per unit area, and size of the sheet The ink jet recording apparatus according to claim 2, wherein the force is corrected. A sheet reversing unit for reversing the conveying direction of the sheet;
The sheet reversing unit is configured to discharge the ink droplets onto the second surface of the sheet opposite to the first surface after the ink droplets are ejected onto the first surface of the sheet. Reverse the transport direction,
The suction force control unit changes the suction force when the transport belt transports the sheet after the transport direction is reversed by the sheet reversing unit. 2. An ink jet recording apparatus according to item 1.   The ink jet recording apparatus according to claim 1, wherein the counting unit initializes a result of the counting when the maintenance mechanism is operated.

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