JP5316443B2 - Inkjet printer - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To enhance the printing quality of rear end part of recording paper where influence of suction of ink by a suction hole easily appears without lowering the printing quality of the other part in an inkjet printer having a conveying mechanism for conveying the recording paper, a platen for attracting and holding the recording paper P conveyed by the conveying mechanism via the suction hole, and a print head H having a plurality of head units 13a, 13b arranged so as to line in the conveying direction of the recording paper P and discharging ink. <P>SOLUTION: The recording paper P is conveyed a predetermined quantity k smaller than a unit conveying quantity T, printing is carried out by only an upstream side head unit 13a when the conveying stops, the recording paper P is conveyed only differential quantity between the unit conveying quantity T an the predetermined quantity k after the printing, and printing is carried out by only a downstream side head unit 13b when the conveying stops, when the upstream side head unit 13a carries out the printing to the rear end predetermined area U of the recording paper P. <P>COPYRIGHT: (C)2011,JPO&amp;INPIT

Description

  The present invention belongs to a technical field related to an ink jet printer.

  Conventionally, a transport mechanism for transporting recording paper, a platen that supports the recording paper transported by the transport mechanism, and a print head having a plurality of head units arranged in the transport direction of the recording paper are provided. Inkjet printers are known. In this ink jet printer, while the recording paper is intermittently transported by a constant unit transport amount by the transport mechanism, ink is ejected from each of the plurality of head units of the print head when the recording paper is stopped during the intermittent transport. An image is printed on recording paper.

  In this type of printer, in order to ensure the flatness of the recording paper during printing, a suction hole is formed on the surface of the platen and a suction device is provided on the back side of the platen. In some cases, it is adsorbed and held on the platen surface.

  In this case, the ink ejected from the print head toward the downstream end or upstream end of the recording paper is sucked into the suction hole due to the negative pressure of the suction device, and the ink landing position is a predetermined landing position. There is a problem that it is displaced from the position.

  In order to solve this problem, in the ink jet printer disclosed in Patent Document 1, a region having a predetermined width from directly below each head unit toward the downstream side of conveyance is set, and the suction hole is closed in each region and the diameter of the suction hole is changed. I try to make it smaller than this part. This prevents ink discharged from the print head toward the downstream end of the recording paper from being transported to the downstream side due to the negative pressure of the suction device.

JP 2007-031007 A

  By the way, in the ink jet printer of the type that holds the recording paper on the platen surface as described above, it is important to ensure that the leading edge of the recording paper adsorbs to the platen surface when the recording paper enters the platen in order to prevent an adsorption error. become. For this reason, the diameter of the suction hole formed on the transport upstream side of the platen may be set larger than that on the transport downstream side. In this case, at the rear end of the recording paper, there is a problem that the influence of ink suction by the suction holes becomes significant and the print quality is extremely lowered.

  To solve this problem, the influence of ink suction by the suction holes at the rear end of the recording paper is reduced by closing a part of the suction holes or reducing the number of suction holes as in the case of Patent Document 1. It is possible. However, in this case, since the adsorption force of the recording paper by the suction holes is reduced as a whole, there is a problem that the flatness of the recording paper cannot be ensured sufficiently.

  Therefore, it is conceivable to prevent the deviation of the ink landing position at the rear end portion of the recording paper by controlling the conveyance amount of the recording paper while maintaining the number of suction holes and the hole diameter. Specifically, when the head unit located on the most upstream side performs printing on the trailing edge of the recording paper, the ink ejected from the head unit toward the trailing edge of the recording paper is drawn toward the upstream side of the conveyance. In anticipation of this, the conveyance amount of the recording paper should be reduced accordingly.

  However, in this case, there is a problem that the print quality is deteriorated due to the influence of this correction on head units other than the most upstream head unit that needs to correct the intermittent conveyance amount.

  The present invention has been made in view of such a point, and an object of the present invention is to convey a recording sheet and to hold the recording sheet conveyed by the conveying mechanism through suction holes. In the ink jet printer having a platen and a print head that is provided so as to be aligned in the recording paper conveyance direction and has a plurality of head units that eject ink, the trailing edge of the recording paper that is likely to be affected by ink suction through the suction holes It is intended to improve the print quality of a part without lowering the print quality of other parts.

  In order to achieve the above object, according to the present invention, when the head unit located on the most upstream side in the transport direction performs printing on the rear end portion of the recording paper, the recording paper is fed by a predetermined amount smaller than the unit transport amount. When the conveyance stops, printing is performed only with the head unit positioned on the most upstream side, and after the printing, the recording paper is conveyed by a difference amount between the unit conveyance amount and the predetermined amount, When the conveyance is stopped, printing is performed only with the other head units except for the head unit located on the most upstream side.

  Specifically, in the first aspect of the invention, a transport mechanism for transporting the recording paper, a platen having a suction hole opened on the surface, and the recording paper transported by the transport mechanism are sucked through the suction hole. The present invention is directed to an ink jet printer that includes a suction device that sucks and holds the platen surface on the platen surface, and a print head that is provided so as to be aligned in the conveyance direction of the recording paper and that has a plurality of head units that discharge ink. .

Of the suction holes formed in the platen, the suction hole located closer to the upstream side of the recording paper is formed so as to have a larger diameter than the suction hole located closer to the downstream side of the transport, The recording paper is intermittently conveyed by a constant unit conveyance amount by a conveyance mechanism, and printing is performed on the recording paper by ejecting ink from each of the plurality of head units of the print head when the recording paper is stopped during the intermittent conveyance. When the normal print control means to perform and the head unit located on the most upstream side in the transport direction among the plurality of head units prints on the rear end portion of the recording paper, the transport mechanism causes the recording paper to be A predetermined amount smaller than the unit transport amount is transported, and when the transport is stopped, ink is ejected from only the head unit located on the most upstream side and printing is performed on the recording paper. After printing by the one correction printing control means and the first correction printing control means, when the recording paper is conveyed by the difference amount between the unit conveyance amount and the predetermined amount by the conveyance mechanism, and the conveyance is stopped And a second correction printing control unit that prints on recording paper by ejecting ink only from other head units except the head unit positioned on the most upstream side.

According to this configuration, when the recording paper enters the platen, the leading end can be reliably held by suction, and a suction error can be prevented as much as possible. In such an ink jet printer, since the hole diameter of the suction hole located on the upstream side of the conveyance is larger than that on the downstream side, the influence of ink suction by the suction hole tends to occur at the rear end portion of the recording paper.

On the other hand , when the head unit located on the most upstream side among the plurality of head units performs printing on the rear end portion of the recording paper, the first correction printing control means sets the recording paper to a predetermined amount smaller than the unit transport amount. When the conveyance is stopped and the conveyance is stopped, printing on the recording paper by the head unit is executed.

  Therefore, even if the ink ejected from the head unit is sucked into the suction hole in the vicinity of the trailing edge of the recording paper and its landing position is shifted to the trailing edge of the recording paper, the amount of conveyance of the recording paper is reduced by that amount. By reducing the size, the ejected ink can be landed at a desired position. At the time of printing by the first correction printing control means, ink is ejected only from the head unit located on the most upstream side, so that the print quality is reduced due to the effect of reducing the transport amount to other head units. Can be prevented.

  After printing by the first correction printing control means (the most upstream head unit), the recording paper is conveyed by the second correction printing control means by the difference amount between the unit conveyance amount and the predetermined conveyance amount, and the conveyance is stopped. In this case, the print processing on the recording paper is executed by the other head units except the head unit located on the most upstream side. Accordingly, in the portion excluding the rear end portion of the recording paper (that is, the portion where the influence of ink suction by the suction holes is small), the first correction printing control means applies the recording paper to the recording paper at the same feed pitch (unit transport amount) as in normal printing control. Printing can be performed.

  According to a second aspect of the present invention, in the first aspect of the invention, the first correction printing control means is configured to perform printing on a region having a predetermined width from the trailing edge of the recording paper toward the leading edge. It shall be.

  According to this configuration, it is possible to reliably prevent the landing position from being shifted due to the suction of ink by the suction holes in a region having a predetermined width from the trailing edge of the recording paper toward the leading edge.

  Here, the region having a predetermined width is a region having a width in which the deviation amount of the ink landing position exceeds a predetermined threshold, and may be set in advance by performing test printing or the like.

  According to a third aspect of the present invention, in the first or second aspect of the invention, the normal printing control means causes the plurality of head units to eject ink during the forward operation and the backward operation of the print head, respectively, thereby the recording paper. The normal print control means is configured to print the ink from the plurality of head units during the forward operation and the backward operation of the print head, respectively. And the second correction printing control means is configured to print the same dots on the recording paper as compared with the case where printing is performed by the normal printing control means. It is assumed that the operation of the print head is controlled so that the direction of movement of the print head when printing on a line is the same.

  According to this configuration, the direction of movement of the print head when printing on the recording paper by the second correction print control unit is the same as the direction of movement of the print head when printing is performed by the normal print control unit. can do. Therefore, it is possible to prevent the image quality from being different between the print image by the normal print control means and the print image by the second correction print control means, and as a result, a color change or the like occurs at the boundary between the two images. Can be prevented from decreasing.

  As described above, according to the ink jet printer of the present invention, it is possible to improve the print quality of the trailing edge of the recording paper that is easily affected by the suction of ink through the suction holes without deteriorating the print quality of other portions. it can.

FIG. 2 is a perspective view illustrating an appearance of the printer according to the embodiment of the present invention, viewed from an oblique right side on the front side of printing. It is the schematic seen from the printer right side which shows the internal structure of a printer. It is a top view which shows the structure of a pair of magazine rollers. FIG. 3 is a front view showing the configuration of a main conveyance roller pair as viewed from the front side of the printer. It is a top view which shows the structure of the platen of a printing part. FIG. 6 is a schematic diagram illustrating a state in which a switchback roller pair of a switchback unit receives a recording sheet conveyed from a pair of conveyance rollers after cutting. FIG. 7 is a view corresponding to FIG. 6 showing a state in which the driven rollers of the switchback roller pair are switched to the second position. FIG. 2 is a block diagram illustrating a configuration of a printer control system. 6 is a flowchart illustrating print control in a print control unit. FIG. 4 is an explanatory diagram of normal print control and correction print control in a print control unit, where (a) is a schematic view of the print head viewed from the main scanning direction, and (b) is a diagram illustrating recording paper held by suction on a platen. FIG. 6 is a diagram schematically illustrating the print head scanning direction, whether or not ink is ejected from the head unit during the scanning, and the conveyance amount of the recording paper when viewed from above.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. It should be noted that the following description of the preferred embodiment is merely illustrative in nature and is not intended to limit the present invention, its application, or its use.

  FIG. 1 is a perspective view showing a partially omitted configuration of an ink jet printer according to an embodiment of the present invention. The printer A is used in a photo print system. For example, the printer A obtains image data and order information and performs necessary correction processing from a reception block 200 (see FIG. 8) via a communication cable. The transmitted image data is configured to be printed on the recording paper P based on the order information.

-Overall configuration-
FIG. 2 is a schematic diagram illustrating the configuration of the printer A. As shown in FIG. 2, the printer A has a recording paper storage unit 1 provided in the lower part of the printer for storing a roll-shaped recording paper P, and a recording paper P drawn from the recording paper storage unit 1. And a printing unit 2 provided on the upper part of the printer so as to perform recording printing of the image data.

  At the upper part of the printer A and on the downstream side of the conveyance of the printing unit 2, a cutter unit 4 that cuts the printed recording paper P into a predetermined print size, and the printed recording paper P is switched back by switching back. The switchback unit 5 for changing the orientation, the back surface printing unit 6 for printing the reference number and the like on the back surface of the recording paper P, the drying unit 7 for drying the printing surface of the recording paper P, and wound in a roll shape A decurling unit 8 for removing the curl of the recording paper P and discharging it, and a conveyor device for distributing the discharged recording paper P to one side of the printer in the left-right direction (direction perpendicular to the paper surface of FIG. 2) 150, receiving a large-sized tray 104 (see FIG. 1) for receiving a large-sized recording paper P such as B5 size or A4 size, and a photo-sized recording paper P such as an L plate Stacking device 210 for integrating each over da is disposed.

  The printer A is covered with a casing 3 except for the large-size tray 104 and the stacking device 210, and a moving caster 3 a is attached to the lower surface of the casing 3.

  The recording paper storage unit 1 is positioned almost directly below the printing unit 2 and can store two magazines M1 and M2 for storing the recording paper P. The magazines M1 and M2 are arranged side by side in the vertical direction, and a roll-shaped recording sheet P is accommodated in the magazines M1 and M2 while being held by the winding core R. In the present embodiment, a roll-shaped recording paper P having a wide size (for example, a width exceeding 12 inches) is accommodated in the magazine M1, and a narrow size (for example, a width of 12 inches or less) is accommodated in the magazine M2. ) Roll-shaped recording paper P is accommodated in two rows in the axial direction.

  The printer A also includes a manual feed unit 9 (recording paper set unit) on which a single sheet of recording paper P cut into a predetermined size is set. It is configured to be able to print on a single sheet of recording paper P.

-Recording paper transport mechanism-
As shown in FIG. 2, the printer A includes a recording paper transport mechanism that pulls out the recording paper P from the recording paper storage unit 1 and transports it along a predetermined transport path while performing various processes such as printing and cutting of images. Is provided in the upper part of the printer.

  In this embodiment, in addition to supplying the recording paper P from the recording paper storage unit 1, the recording paper P having a predetermined size is supplied from the manual feed tray 102 via the manual feed roller pair 27 (auxiliary transport roller pair). A manual feeder 9 configured to be able to be provided is provided. In the following description, the side on which the manual feed tray 102 is provided is defined as the front side of the printer, and the opposite side is defined as the rear side of the printer. Further, the left side when viewed from the front side of the printer is defined as the left side of the printer, and the right side is defined as the right side of the printer.

  The recording paper storage unit 1 stores two magazines M1 and M2, and when printing on a wide size recording paper P, the recording paper P stored in the magazine M1 is the leading end of the recording paper P. The magazine is pulled out from the magazine and is fed out of the magazine by the magazine roller pair 22 while being guided by the guide roller 21. The recording paper P sent out of the magazine passes through a branch portion 23b on the rear side of the printer of the guide portion 23 branched into two on the upstream side, and is disposed opposite to the supply roller 24 and the supply roller 24 that form the recording paper conveyance mechanism. It is sandwiched between a pair of pressure rollers 24a and 24b. The pressure roller 24 a (or pressure roller 24 b) and the supply roller 24 constitute a main conveyance roller pair 100. Note that only one of the pair of pressure rollers 24a and 24b may be provided.

  The recording paper P conveyed by the rotation of the supply roller 24 is supplied to the printing unit 2 on the downstream side of the conveyance, and an image is printed on the recording paper P by the print head H.

  When printing on a narrow-sized recording sheet P, both or one of the two roll-shaped recording sheets P accommodated in the magazine M2 is pulled out from the leading end portion and pulled out. P is fed out of the magazine by the magazine roller pair 22 while being guided by the guide roller 21. The recording paper P sent out of the magazine passes through the branch portion 23a on the front side of the printer of the guide portion 23, is sandwiched between the supply roller 24 and the pair of pressure rollers 24a and 24b, and is supplied to the printing portion 2. Then, an image is printed on the recording paper P by the print head H.

  The guide portion 23 guides the leading end portion of the recording paper P so as not to deviate from the conveyance path, and positions the recording paper P in the width direction.

  The printed recording paper P is sent to the cutter unit 4 by the post-printing conveyance roller pair 25 and cut into a predetermined print size. The cut recording paper P is delivered to the switchback unit 5 by the three post-cutting conveyance roller pairs 26. These three post-cutting conveying roller pairs 26 are prepared for receiving the recording paper P that is transported next after the recording paper P is delivered to the switchback unit 5 and then simultaneously released from pressure bonding.

  In the switchback unit 5, the cut recording paper P is received from the leading end side and drawn by the switchback roller pair 73, and then the conveyance direction is changed from the horizontal direction to the vertical direction (from the horizontal direction in FIG. 2 to the vertical direction). Change and discharge from the rear end.

  The recording paper P discharged from the switchback unit 5 is sent to the back surface printing unit 6 by the supply roller pair 75 and printed with a serial number on the back surface of the recording paper P and then conveyed to the drying unit 7. .

  In the drying unit 7, the printing surface P is dried while being transported by the transport roller pair 28. The recording paper P that has been dried is sent to the decurling unit 8 by the conveying roller pair 29.

  In the decurling unit 8, in order to remove the curling of the recording paper P wound in a roll shape, the decurling roller 82 is moved between the driving conveying roller 81 while the recording conveying P is sandwiched and conveyed by the driving conveying roller 81 and the decurling roller 82. It moves to the clockwise direction of FIG. 2 along an outer peripheral surface. As a result, the recording paper P is decurled while being bent in a direction opposite to the curling direction, and is discharged from the discharge port 90 onto the conveying belt 151 of the conveyor device 150.

-Details of each component-
Hereinafter, each component of the printer A will be described in detail. The recording paper storage unit 1 is provided with a slide base 30 on which the magazines M1 and M2 are placed. The slide table 30 is configured to be slidable in the front-rear direction of the printer by linear guides (not shown) provided on the left and right sides in the housing 3 and extending in the front-rear direction of the printer. Thus, the magazines M1 and M2 can be taken in and out of the housing 3 by sliding the slide table 30. The front surface of the slide table 30 is covered with a door member 31 that forms a part of the housing 3 and can be opened and closed, and the recording paper P is replaced by opening the door member 31. Can do.

  In the following description, the left side of FIG. 2 (showing a state where magazines M1 and M2 are set in the recording paper storage unit 1) is defined as the magazine front side, and the right side is defined as the magazine rear side. Further, a direction perpendicular to the paper surface of FIG. 2 is defined as a magazine length direction (a direction matching the printer left-right direction).

  The magazines M1 and M2 are substantially hermetically sealed box-type containers configured to be portable. An opening 111 for pulling out the recording paper P stored in the magazines M1 and M2 to the outside of the magazines M1 and M2 is formed at the front end of the magazines M1 and M2. The opening 111 has a substantially rectangular shape extending in the magazine length direction. The magazines M1 and M2 are provided with an opening / closing shutter mechanism (not shown) for opening and closing the opening 111, and the magazines M1 and M2 are left for a long time with the opening 111 opened. The air in the magazines M1 and M2 is prevented from drying, and the recording paper P in the magazines M1 and M2 is protected from cracks and the like.

  The magazine roller pair 22 provided in the recording paper storage chambers S1 and S2 inside the magazines M1 and M2 is a pressure-bonding roller pair including a magazine driving roller 32 and a magazine driven roller 33.

  Here, in the magazine M1 in which the wide-sized recording paper P is accommodated, both the magazine driving roller 32 and the magazine driven roller 33 are configured by a single cylindrical roller.

  On the other hand, in the magazine M2 in which the narrow size recording paper P is accommodated, the magazine driven roller 33 is constituted by a single cylindrical roller, whereas the magazine driving roller 32 has a left divided roller 32a and a right divided roller. Two cylindrical rollers with the roller 32b are arranged in series (coaxially) (see FIG. 3). The left and right divided rollers 32 a and 32 b constituting the magazine drive roller 32 are connected to left and right drive motors 91 provided in the housing 3 and can be driven independently. One of the left and right drive motors 91, 91 (in this embodiment, the left drive motor 91) is also used as a drive source for the magazine drive roller 32 provided in the magazine M1.

  The left and right divided rollers 32a and 32b constituting the magazine drive roller 32 in the magazine M2 are set to a length corresponding to the width of each recording paper P. When both the left and right recording papers P stored in the magazine M2 are pulled out, both the left and right divided rollers 32a and 32b are driven by the drive motor 91. Further, when pulling out only one of the two rows of recording paper P accommodated in the magazine M <b> 2, only the division rollers 32 a and 32 b corresponding to the one recording paper P are driven by the drive motor 91. When pulling out the wide-sized recording paper P stored in the magazine M1, the magazine driving roller 32 disposed in the magazine M1 is driven by the left driving motor 91.

  Here, in FIG. 3, the left and right divided rollers 32 a and 32 b are directly connected to the drive motor 91, but actually, the drive motor 91 is fixed to the motor mounting base in the housing 3, and the magazine When M1 is set at a predetermined position, the left and right drive motors 91 are connected to the respective divided rollers 32a and 32b via gear mechanisms (not shown). The left drive motor 91 is also coupled to the magazine drive roller 32 in the magazine M2 when the magazine M2 is set at a predetermined position.

  As described above, in this embodiment, the magazine drive roller 32 in the magazine M2 is composed of the two divided rollers 32a and 32b, and each of the divided rollers 32a and 32b can be independently driven by different drive motors 91. . Therefore, as described above, by controlling the driving of the left and right divided rollers 32a and 32b constituting the magazine driving roller 32, only the necessary recording paper P is selectively pulled out of the recording paper P in the magazine M2. be able to. In addition, the motor which drives each roller 32a, 32b is controlled by the conveyance control part 202 mentioned later.

  FIG. 4 is a front view showing the configuration of the main conveyance roller pair as viewed from the front side of the printer. As shown in FIGS. 2 and 4, the main conveyance roller pair 100 includes a supply roller 24 and two pressure rollers 24 a and 24 b.

  The supply roller 24 is composed of a single cylindrical roller. The pressure-bonding rollers 24a and 24b are constituted by divided rollers having a roller surface 24c that is divided into a plurality at intervals in the axial direction. The supply roller 24 is driven by a motor (not shown), rotates in the forward direction to pull out the recording paper P from the recording paper storage unit 1 and transport it to the printing unit 2 side, and the recording paper P into the recording paper storage unit 1. The rotation in the reverse direction can be switched.

  Thus, after the printed portion of the recording paper P is cut into a predetermined size by the cutter unit 4 on the downstream side of the supply roller 24, the long recording paper P is returned to the upstream side and the head of the recording paper P is started. When printing is performed, or when a single sheet of recording paper P is supplied from the manual feed unit 9 instead of the long recording paper P, the long recording paper P can be returned to the recording paper storage unit 1. It can be done. A motor that drives the supply roller 24 is controlled by a conveyance control unit 202 described later.

  On the downstream side of the supply roller 24, a sensor 42 (consisting of a light projecting part and a light receiving part) for detecting the leading edge of the recording paper P sent out from the supply roller 24 is disposed. From the detection of the leading edge of the recording paper P by the sensor 42, when the recording paper P is conveyed by the supply roller 24 by an amount such that the print start portion of the recording paper P reaches the lower position of the print head H, the recording paper P Start printing on Further, when the leading edge of the recording paper P is detected by the sensor 42, when the recording paper P is conveyed by the supply roller 24 by an amount such that the leading edge of the recording paper P reaches the conveyance roller pair 25 after printing, the supply roller 24 Is changed from the pressure-bonded state to the pressure-released state, and the post-printing conveyance roller pair 25 is changed from the pressure-released state to the pressure-bonded state.

  On the other hand, a manual feed roller pair 27 is disposed on the upstream side (front side of the printer) of the main transport roller pair 100. This pair of manual feed rollers 27 is for pulling out the sheet-like recording paper P set on the manual feed tray 102 and transporting it to the main transport roller pair 100. On the printing surface of the recording paper P by the printing unit 2 is provided. A manual drive roller 27a that comes into contact with a manual feed roller 27b that comes into contact with a surface opposite to the printing surface is provided.

  The manual feed roller 27a is a so-called half-moon roller with a part of the roller surface cut. When the manual feed roller 27a is driven by a motor (not shown), the recording paper P on the manual feed tray 102 is pressure-bonded to the roller surface and sent toward the main conveying roller pair 100. When the leading end portion of the recording paper P is transferred to the main transport roller pair 100, the cut portion of the roller surface and the manual driven roller 27b face each other, so that the pressure supply state of the manual feed roller pair 27 is released. The

  The printing unit 2 ejects ink onto the recording paper P, thereby forming a print head H that forms an image composed of a large number of ink dots, and the recording paper P provided below the printing head H is sucked to the printing position. And a recording paper holding unit D for holding the recording paper. On the downstream side of the recording paper holder D, a pressure-bonding post-printing conveyance roller pair 25 is disposed.

  The print head H is configured to be movable along a guide rail (not shown) extending in the main scanning direction X. Furthermore, the print head H has two head units 13a and 13b arranged in the sub-scanning direction (recording paper transport direction) Y, and ink is discharged from the ink discharge nozzles provided in these head units 13a and 13b. By discharging, a predetermined image, character, or the like can be printed on the recording paper P. In the following description, the head unit 13a located on the upstream side of conveyance is referred to as an upstream head unit 13a, and the head unit 13b located on the downstream side of conveyance is referred to as a downstream head unit 13b.

  Here, the main scanning direction X corresponds to the left-right direction of the printer (also the width direction of the recording paper P), and the sub-scanning direction Y corresponds to the front-rear direction of the printer.

  Seven ink cartridges (not shown) in which inks having different hues are sealed are detachably accommodated in the lower portions on the left and right sides of the inkjet printer A, respectively. Accordingly, by attaching or detaching these ink cartridges from the case, it is possible to exchange used or used ones with new ones.

  Each of these ink cartridges includes yellow (Y), magenta (M), cyan (C), black (K), red (R), violet (V), and clear (CL: transparent) inks. Is enclosed.

  Each of the head units 13a and 13b has the same configuration, and each of the head units 13a and 13b includes a plurality of nozzle arrays that eject inks arranged in the main scanning direction X. In each nozzle array, ink discharge nozzles are arranged in a row in the sub-scanning direction Y. Thereby, each head unit 13a, 13b is set as the structure which can form a color image independently.

  Here, the configuration of each of the head units 13a and 13b is not particularly limited, but each head unit 13a and 13b in the present embodiment is provided for each ink discharge nozzle and is filled with ink. It is a general piezo system that ejects ink by changing the volume of a chamber by a piezoelectric element (piezo element).

  Then, the recording paper P on the recording paper holding section D is intermittently (stepwise) at a constant unit transport amount T by the supply roller 24 provided on the upstream side of the recording paper holding section D in the sub-scanning direction. When the recording paper P is conveyed to Y, and the recording paper P is stopped during this intermittent conveyance, the print head H is scanned one time in the main scanning direction (one-way operation or one-time operation). Thus, ink is ejected from the ink ejection nozzles of the head units 13a and 13b. In this embodiment, as will be described in detail later, the recording paper P is transported by a transport amount smaller than the unit transport amount T (= predetermined amount k or difference amount d) under predetermined conditions. When stopped, the print head H is scanned once in the main scanning direction, and ink is ejected from either one of the head units 13a and 13b. Thus, a desired image composed of a plurality of dot rows arranged in the recording paper conveyance direction is printed on the recording paper P.

  Further, a head standby position for the print head H to wait when printing is not being performed is set at a position outside the print area in the main scanning direction X of the print head H. Cap portions (not shown) are provided to be in close contact with the head units 13a and 13b of the print head H in order to prevent the ink from thickening when the print head H is not used.

  As shown in FIG. 5, the recording paper holder D has a plurality of suction holes 60 opened on the surface (upper surface) corresponding to the print area of the print head H, and a flushing hole 61 corresponding to the flushing area. The recording paper P is removed from the platen 45 through the suction holes 60 by sucking and exhausting air in a space provided in the platen 45 below the print area of the print head H and communicating with the suction holes 60. A suction fan (not shown) is provided as a suction device that sucks and holds the surface.

  A large number of the suction holes 60 are formed in the passage region of the recording paper P on the surface of the platen 45. The suction hole 60a located on the most upstream side of the platen 45 is formed so as to have a larger hole diameter than the other suction holes 60b. As a result, the leading edge of the recording paper P that has entered the platen 45 can be reliably sucked and held by the platen 45, and a suction error can be prevented as much as possible.

  The flushing hole 61 is for receiving a small amount of ink ejected from the ink ejection nozzle of the print head H at the start of printing in order to prevent the ink from thickening. The waste ink ejected into the flushing hole 61 is The liquid is stored in a waste liquid tank (not shown) through a waste pipe.

  A plurality of recesses 45b extending in the sub-scanning direction Y are formed on the support surface 45a of the platen 45 at intervals in the main scanning direction X (14 locations in FIG. 5). An ink absorbing member 72 is accommodated in the recess 45b. When the ink absorbing member 72 performs borderless printing for printing an image on the entire recording paper P, a part of the ink ejected from each head unit 13a, 13b of the print head H is recorded on the recording paper P on the support surface 45a. This is provided in order to prevent the support surface 45a of the platen 45 from being soiled by the ink that has come off the outside even if it protrudes outward from the edge in the width direction. For this reason, the concave portion 45b is located along the edge at a position corresponding to the edge in the width direction of the recording paper P on the support surface 45a on the support surface 45a and at a position corresponding to the print head H in the sub-scanning direction Y. It is formed to extend (that is, to extend in the sub-scanning direction Y).

  The ink absorbing member 72 is formed in a substantially rectangular parallelepiped shape extending in the sub-scanning direction Y along the recess 45b. The ink absorbing member 72 is detachably accommodated in the recess 45b. In the state where the ink absorbing member 72 is accommodated in the recess 45 b, the longitudinal direction of the ink absorbing member 72 coincides with the sub-scanning direction Y.

  Further, a protrusion 46 is formed on the inner peripheral surface of the recess 45b so as to protrude inward of the recess 45b. Six projections 46 are formed at intervals in the inner circumferential direction, and the ink absorbing member 72 is positioned by the tip of the projection 46 contacting the outer circumferential surface of the ink absorbing member 72. . Here, since the protrusion 46 of the recess 45 b is in contact with the ink absorbing member 72, a gap is formed between the inner peripheral surface of the recess 45 b and the outer peripheral surface of the ink absorbing member 72. This gap communicates with the waste liquid tank through a waste pipe.

  With such a configuration, a large amount of waste ink is generated by continuously printing images with the print head H, and even if the waste ink cannot be completely absorbed by the ink absorbing member 72, the waste ink is removed from the gap. It can be recovered.

  The cutter unit 4 is disposed on the lower side of the conveyance path of the recording paper P and the fixed blade 4a on the upper side of the conveyance path of the recording paper P, and is vertically moved with respect to the fixed blade 4a by a motor (not shown). The movable blade 4b moves to the lower side of the recording paper P, and the recording paper P is cut. Chips resulting from this cutting fall and are stored in a waste box (not shown) disposed in the lower part of the housing 3.

  The switchback unit 5 switches back the recording paper P and discharges the recording paper P from the rear end side of the recording paper P to the transport path so that the printing surface of the recording paper P faces the upper surface on the transport belt 151 of the conveyor device 150. It is something to be made.

  As shown in FIG. 2, FIG. 6 and FIG. 7, the switchback portion 5 includes a pair of pressure-switching switchback rollers 73 composed of a lower driving roller 73a and an upper driven roller 73b, and the switchback roller. A pair of first guide members 74 that are provided on the upstream side of the pair 73 so as to sandwich the conveyance path and guide the recording sheet P conveyed by the conveyance roller pair 26 after cutting to the switchback roller pair 73, and the switched back recording. Supplying the switch-backed recording paper P provided to sandwich the conveyance path between the pressure-feed type supply roller pair 75 for supplying the paper P to the back surface printing unit 6, and the switchback roller pair 73 and the supply roller pair 75. A pair of second guide members 76 that lead to the roller pair 75 are provided.

  The driving roller 73a of the switchback roller pair 73 is driven forward by a motor (not shown) to sandwich the recording paper P and transport it to the front side of the printer, and reversely rotated to sandwich the recording paper P and transport it to the rear side of the printer. And is configured to be possible.

  The switchback roller pair 73 and the first guide member 74 can be moved integrally around the rotation axis of the drive roller 73a of the switchback roller pair 73 by a motor (not shown). The relative position of the driven roller 73b with respect to the driving roller 73a of the roller pair 73 is positioned almost directly above the driving roller 73a as shown in FIG. 6, and the first position for conveying the recording paper P to the rear side of the printer. As shown in FIG. 7, the switch is switched to the second position which is located on the rear side of the printer with respect to the driving roller 73a and supplies the switched back recording paper P to the back surface printing unit 6 from the rear end side. It has become.

  Here, a switchback operation for switching back the recording paper P transported from the transport roller pair 26 after cutting will be described. When the switchback roller pair 73 receives the recording paper P conveyed from the conveying roller pair 26 after cutting, the driving roller 73a is rotating forward and the driven roller 73b is in the first position. Then, when the recording paper P is conveyed to the rear side of the printer by the switchback roller pair 73 such that the rear end of the recording paper P is positioned on the first guide member 74 (see FIG. 6), the drive roller 73a is rotated forward. To stop.

  At this time, the leading end portion of the recording paper P is bent and bent downward due to the weight of the recording paper P. When the recording paper P is stiff and does not bend due to its own weight, the leading end of the recording paper P is bent downward along the curved guide plate 77 by contacting the curved guide plate 77 provided on the downstream side of the conveyance. It is supposed to be.

  Subsequently, the switchback roller pair 73 and the first guide member 74 are rotated clockwise in FIG. 6 to switch the driven roller 73b from the first position to the second position. Thereby, the rear end side (front side of the printer) of the recording paper P is lifted.

  Thereafter, the driving roller 73a is rotated in the reverse direction, and the recording paper P is conveyed from the rear end side toward the supply roller pair 75 disposed on the upper side of the printer. The recording paper P to be switched back by the switchback roller pair 73 reaches the supply roller pair 75 through the first guide member 74 and the second guide member 76.

  In the present embodiment, the position of the switchback roller pair 73 is switched between the first position and the second position by moving the driven roller 73b around the drive roller 73a of the switchback roller pair 73. However, the present invention is not limited to this configuration. For example, the drive roller 73a and the driven roller 73b are both movable, and the first position and the first position can be changed by changing the position of the entire switchback roller pair 73. The position 2 may be switched.

  Further, in the present embodiment, the switchback roller pair 73 is configured by the driving roller 73a that conveys the recording paper P and the driven roller 73b that rotates following the driving roller 73a. However, the driven roller 73b can be driven. Thus, both of the rollers constituting the switchback roller pair 73 may be configured by the drive roller 73a.

  A recording paper collection box 83 that opens upward is provided below the switchback unit 5. The recording paper collection box 83 is for collecting the recording paper P remaining in the transport path when an error (for example, a paper jam error) occurs. When an error occurs, the recording paper P remaining on the transport path is transported to the switchback unit 5 by the recording paper transport mechanism. The switchback unit 5 receives the recording paper P and discharges it to the recording paper collection box 83. As a result, when an error occurs, the recording paper P remaining in the transport path can be easily removed without opening a necessary portion of the printer cover (housing 3).

  The back surface printing unit 6 is composed of a dot impact type thermal printer, and is disposed on the back surface side of the recording paper P (on the rear side of the printer with respect to the transport path).

  On the downstream side of the conveyance of the back surface printing unit 6, a conveyance roller pair 28 for feeding the recording paper P after the back surface printing is disposed. Then, the recording paper P is transported to the drying unit 7 on the downstream side by the rotation of the transport roller pair 28.

  The drying unit 7 records a suction fan 54 for taking air into the drying device 53, a heater 55 for heating the air taken in by the suction fan 54, and the air heated by the heater 55 as dry air. The exhaust nozzle unit 56 is configured to spray on the printing surface of the paper P.

  The decurling unit 8 includes a driving conveyance roller 81 and a decurling roller 82 configured to be movable around the driving conveyance roller 81. The decurling unit 8 switches the position of the decurling roller 82 between the transport position and the decurling position according to the type of recording paper P (roll paper / cut sheet).

  The conveyance position is defined as a position where the decurling roller 82 is located directly above the driving conveyance roller 81. At this transport position, the recording paper P is transported without being decurled by both rollers 81 and 82.

  The decurling position is defined as a position where the decurling roller 82 is rotated in the clockwise direction around the driving conveying roller 81 from the conveying position. At this decurling position, the recording paper P is conveyed while being decurled by both rollers 81 and 82.

  The decurling unit 8 controls the decurling roller 82 to the conveying position when the recording sheet P conveyed from the drying unit 7 is a single-sheet recording sheet P fed from the manual feed unit 9. When the recording paper P is a roll-shaped recording paper P drawn from the magazines M1 and M2, the decurling roller 82 is controlled to the decurling position. Accordingly, the recording paper P drawn from the magazines M1 and M2 can be surely decurled without unnecessarily curling the recording paper P supplied from the manual feed supply unit 9.

  The accumulating device 210 is for accumulating the recording paper P conveyed from the conveyor device 150, and is disposed at the upper and lower ends of the accumulating main body 211, and a box-shaped accumulating main body 211 having an opening on the front side of the printer. An endless stacking belt 213 wound around the pair of rollers (not shown) with an appropriate tension, and a stacking plate 212 provided on the outer peripheral surface of the stacking belt 213 at substantially equal intervals. Yes. The roller pair is connected to a drive motor (not shown) for rotating the accumulation belt 213 to move the accumulation plate 212 in the transport direction.

  Of the plurality of stacking plates 212, the stacking plate 212 exposed to the outside of the stacking main body 211 moves downward following the rotation of the stacking belt 213, and is accommodated inside the stacking main body 211. The collecting plate 212 is configured to move upward following the rotation of the collecting belt 213. That is, the accumulation plate 212 is configured to be able to rotate continuously around the roller pair together with the accumulation belt 213.

  The stacking plate 212 waits at the delivery position of the recording paper P on the downstream side of the conveyance belt 151 so that the plate surface is horizontal and substantially flush with the belt surface of the conveyance belt 151. After the number of sheets corresponding to 1 is accumulated, the recording paper P of the next order is conveyed downward by the accumulation belt 213 before being conveyed.

-Control system configuration-
As shown in FIG. 8, the inkjet printer A has a microprocessor 201 (hereinafter referred to as a CPU), a conveyance control unit 202 connected to the CPU 201 via a data bus, a head control unit 203, a print system, and the like. A control unit 204, a semiconductor memory RAM / ROM 205, and a communication interface 206 are provided.

  The conveyance control unit 202 controls the operation of the recording paper conveyance mechanism. The head control unit 203 controls the print head H by reciprocating the print head H in the main scanning direction and supplying a voltage having a predetermined waveform to each piezoelectric element. The communication interface 206 is for transmitting and receiving information to and from the reception block 200. Each of the conveyance control unit 202 and the head control unit 203 receives a command from the print control unit 204 and outputs a necessary control signal. The print control unit 204 performs control for realizing printing of image data on the recording paper P based on the image data received from the reception block 200 via the communication interface 206. Here, the order information includes print channel information for specifying the size of the recording paper P to be printed, and print form information for specifying the number of printed sheets.

-About print control in the print controller-
The print control unit 204 intermittently transports the recording paper P by a constant unit transport amount T by the recording paper transport mechanism, and the two head units 13a and 13b of the print head H when the recording paper P is stopped during the intermittent transport. Normal printing control for printing on the recording paper P by discharging ink from each of the recording paper P, and when the upstream head unit 13a performs printing on the predetermined area U at the rear end of the recording paper P, the recording paper P is unitized by the transport mechanism. A first correction printing control in which a predetermined amount k smaller than the transport amount T is transported and ink is ejected only from the upstream head unit 13a when the transport is stopped, and printing is performed on the recording paper P; The recording paper P is transported by a difference amount d between the unit transport amount T and the predetermined amount k, and ink is ejected only from the downstream head unit 13b when the transport is stopped. It is configured to perform a second correction print control for printing on paper P.

  When the recording paper P to be printed is a roll-like recording paper P drawn from the magazines M1 and M2, the print control unit 204 executes only the normal printing control and performs the first and second corrections. Do not execute print control. On the other hand, when the recording paper P to be printed is the single-sheet recording paper P supplied from the manual feed unit 9, the print control unit 204 performs the first and second in addition to the normal printing control. Execute correction printing control.

  The aforementioned “predetermined rear end area U of the recording paper P” is an area having a predetermined width W from the rear end edge of the recording paper P toward the front end, and the deviation amount of the ink landing position is negative in the suction hole 60. This is an area where the threshold is exceeded due to the pressure. The width W is set at the design stage by performing test printing or the like in advance.

  The print control unit 204 executes the normal printing control until the trailing edge position of the recording paper P reaches the setting position set on the conveyance path, while the trailing edge position of the recording paper P has passed the setting position. After that, that is, after the upstream side head unit 13a starts printing in the rear end predetermined area U, the first correction printing control and the second correction printing control are alternately executed.

  For example, the set position may be a position separated from the head unit (substantially central position in the transport direction) by the predetermined width W from the transport upstream side.

  The print control in the print control unit 204 will be specifically described with reference to the flowchart of FIG.

  In the first step S1, the detection information of the recording paper P from each sensor 42, the rotational speed information from each drive motor constituting the recording paper transport mechanism, and the image data information and order information from the receiving block are read.

  In step S2, it is determined whether there is a print request based on the order information read in step S1, etc., and if this determination is NO, the process returns. If YES, the process proceeds to step S3.

  In step S3, it is determined whether normal printing conditions for executing normal printing control are satisfied. Specifically, first, the rear end position of the recording paper P is calculated from the detection information of the recording paper P read in step S1 and the rotational speed information of each drive motor. If it is determined that the calculated trailing edge position of the recording paper P is on the upstream side of the set position, the process proceeds to step S4 on the assumption that the normal printing condition is satisfied. Advances to step S7 assuming that the normal printing conditions are not satisfied.

  In step S4, a normal printing program stored in a memory (not shown) is read, and the following steps S5 and S6 are executed.

  In step S5, a necessary control signal is output to the conveyance control unit 202, whereby the recording paper P is conveyed by the unit conveyance amount T by the recording paper conveyance mechanism.

  In step S6, a necessary control signal is output to the head control unit 203, and after the recording paper P is stopped, the print head H is scanned in the main scanning direction, and ink is ejected from each of the head units 13a and 13b. Print. The direction in which the print head H is scanned is set in the opposite direction to the previous execution of this step. Returns after executing this step.

  In step S7 which proceeds when the determination in step S3 is NO, the corrected printing program is read and the following steps S8 to S11 are executed.

  In step S <b> 8, a necessary control signal is output to the conveyance control unit 202, so that the recording paper P is conveyed by a predetermined amount k smaller than the unit conveyance amount T by the recording paper conveyance mechanism.

  In step S9, by outputting a necessary control signal to the head controller 203, after the recording paper P is stopped, the print head H is scanned in the main scanning direction, and ink is ejected only from the upstream head unit 13a. Print.

  In step 10, a necessary control signal is output to the conveyance control unit 202, so that the recording paper P is conveyed by the recording paper conveyance mechanism by a difference amount d (= T−k) between the unit conveyance amount T and the predetermined amount k. Transport.

  In step S11, by outputting a necessary control signal to the head controller 203, after the recording paper P is stopped, the print head H is scanned in the main scanning direction, and ink is ejected only from the downstream head unit 13b. Print. The scanning direction of the print head H is set to be the same as the scanning direction of the print head H in step S9. After executing step S11, the process returns.

  FIG. 10 shows the operation of the print head H when printing is performed on the sheet-like recording paper P by the ink jet printer A (the direction of scanning of the print head H and the ink ejection from each head unit during the scanning). FIG. 6 is a diagram schematically showing the presence or absence) and the transport amount (that is, the feed pitch) of the recording paper P. When printing the recording paper P, the print control unit 204 first executes normal printing control, so that the recording paper P is intermittently conveyed by the unit transport amount T toward the transport downstream side (in the direction of the thick arrow in FIG. 10). While being conveyed, at each stop during the intermittent conveyance, the print head H performs one scan in the main scanning direction X, and ink is ejected from the head units 13a and 13b. The print head H performs forward and reverse operations alternately. Thus, an image composed of a plurality of dot rows arranged in the recording paper conveyance direction is printed on the printing surface of the recording paper P.

  After the trailing edge position of the recording paper P reaches the set position, the upstream head unit 13a starts printing on the trailing edge predetermined area U set on the printing surface of the recording paper P.

  Here, the rear end predetermined region U is close to the suction hole 60 formed on the upstream side of conveyance of the platen 45, so that the ink ejected from the upstream head unit 13a is sucked into the suction hole 60 and landed. There is a problem that the position shifts to the upstream side of conveyance. In particular, in the ink jet printer according to the present embodiment, this problem becomes significant because the hole diameter of the suction hole 60a located on the most upstream side of the platen 45 is set larger than the hole diameters of the other suction holes 60b.

  On the other hand, in the present embodiment, after the trailing edge position of the recording paper P reaches the set position, the print control unit 204 first executes the first correction printing control, and the conveyance amount of the recording paper P is increased. The predetermined amount k is smaller than the unit transport amount T (the process of step S8 is executed, see FIG. 10B). Therefore, even if the landing position of the ink ejected from the upstream head unit 13a to the predetermined rear end region U is shifted to the upstream side due to the negative pressure of the suction hole 60, the transport amount of the recording paper P is correspondingly increased. By reducing the size, the ejected ink can be landed at a desired position. Further, when the print head H scans when the conveyance of the recording paper P is stopped, since the ink is ejected only from the upstream head unit 13a (because the process of step S9 is executed), the downstream head unit. It is possible to prevent the landing position of the ink in the printing region, which is affected by the reduction of the transport amount up to 13b and is less affected by the suction hole 60 from being shifted to the recording paper front end side.

  After the first correction printing control is executed by the print control unit 204, the second correction printing control is executed. As a result, the recording paper P is transported by a difference amount d between the unit transport amount T and the predetermined transport amount k (the processing of step S10 is executed), and when the transport is stopped, the downstream head unit 13b. A printing process on the recording paper P is executed (the process of step S11 is executed). Accordingly, in the portion of the printing surface of the recording paper P excluding the predetermined rear end region U, that is, the portion where ink is hardly sucked by the suction holes 60, the transport amount (feed pitch) of the recording paper P is set to the unit transport amount T. Can be printed. Therefore, it is possible to prevent the image quality of the two images from differing by matching the dot row interval of the image between the print image by the normal print control and the print image by the second correction print control.

  Further, the print control unit 204 performs normal printing without executing the first correction print control on the predetermined area of the rear end of the recording paper P, for the scanning direction of the print head H when executing the second print control. The operation of the print head H is controlled so as to be in the same direction as compared with the case where the control is executed. This means that in the process of step S11 in the print control unit 204, the scan direction of the print head H when executing the second print control is the scan direction of the print head H when executing the first print control immediately before that. It is realized by matching.

Thereby, it is possible to more reliably prevent the image quality from being different between the print image by the normal print control and the print image by the second correction print control.
(Other embodiments)
The configuration of the present invention is not limited to the previous embodiment, but includes various other configurations. That is, in the above embodiment, the print head H is assumed to have two head units 13a, 13, not limited thereto, may have three or more Heddoyuni' bets.

Further, in the above embodiment, so that set larger than the diameter of the suction holes 60a located on the most upstream side of the platen 45 in the hole diameter of the other of the suction holes 60b, not limited thereto, examples For example, the hole diameters of the suction holes 60a in the range of 3 to 5 lines from the uppermost stream side toward the downstream side may be set larger than the hole diameters of the other suction holes 60b.

The present invention provides a transport mechanism for transporting recording paper, a platen having a suction hole opened on the surface, and sucks the recording paper transported by the transport mechanism through the suction hole to adsorb onto the platen surface. a suction device for holding, an inkjet printer including a printhead, a having a plurality of head units for ejecting and ink is provided so as to be aligned in the transport direction of the recording paper, the position on the conveyor upstream side of the platen This is useful for an ink jet printer in which the diameter of the suction hole to be set is relatively large.

A Inkjet printer H Print head P Recording paper T Unit transport amount W Predetermined width X Main scanning direction d Difference amount k Predetermined amount 13a Upstream head unit 13b Downstream head unit 24 Supply roller (recording paper transport mechanism)
24a Pressure roller (recording paper transport mechanism)
24b Pressure roller (recording paper transport mechanism)
45 platen
60 Suction hole 204 Print control unit (normal print control means, first correction print control means, second correction print control means)

Claims (3)

A transport mechanism for transporting recording paper, a platen having suction holes opened on the surface, and a suction device for sucking and holding the recording paper transported by the transport mechanism through the suction holes on the platen surface And a print head having a plurality of head units that are provided so as to be aligned in the conveyance direction of the recording paper and eject ink,
Of the suction holes formed in the platen, the suction holes located closer to the upstream side of the recording paper are formed so that the hole diameter is larger than the suction holes located closer to the downstream side of the transport,
The recording paper is intermittently transported by a constant unit transport amount by the transport mechanism, and ink is ejected from each of the plurality of head units of the print head when the recording paper is stopped during the intermittent transport. Normal printing control means for performing,
When the head unit located on the most upstream side in the transport direction among the plurality of head units performs printing on the rear end portion of the recording paper, the transport mechanism causes the recording paper to be smaller than the unit transport amount. First correction printing control means for carrying out printing on a recording sheet by ejecting ink only from the head unit located on the most upstream side when the conveyance is stopped,
After printing by the first correction printing control means, the recording mechanism conveys the recording paper by the difference amount between the unit conveyance amount and the predetermined amount, and is positioned on the most upstream side when the conveyance is stopped. An ink jet printer comprising: a second correction printing control unit that discharges ink from only the other head unit excluding the head unit and performs printing on the recording paper. The inkjet printer according to claim 1.
The ink jet printer according to claim 1, wherein the first correction printing control unit is configured to perform printing on a region having a predetermined width from the trailing edge of the recording paper toward the leading edge. The inkjet printer according to claim 1 or 2,
The print head is configured to be capable of reciprocating in a main scanning direction orthogonal to the conveyance direction of the recording paper,
The normal printing control unit prints an image composed of a plurality of dot rows arranged in the transport direction on the recording paper by ejecting ink from the plurality of head units during the forward operation and the backward operation of the print head. Is configured to
The second correction printing control unit is configured so that the print head moves in the same direction when printing on the same dot row of the recording paper as compared with the case where printing is performed by the normal printing control unit. And an ink jet printer configured to control the operation of the print head.

Images