JP2016155365A - Printing apparatus and printing control program - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a printing apparatus capable of suppressing reduction in printing quality due to a deviation of an impact position of liquid occurring in the transport direction of a medium, and a printing control program executed in the printing apparatus.SOLUTION: When printing is performed on a medium, a computer of a printing apparatus acquires an interval (an LPG level number and a thickness of the medium) between a surface of the medium and a print head, which is formed when an ink is discharged onto the medium from the print head in a printing unit (S14). Highness or lowness of a carriage speed (print speed mode), a print color (monochrome or color), and a transport region (normal region or lower end region) as a transport position of the medium are determined (S15-S17). A calculation expression is selected depending on the carriage speed, the print color, and the transport region, and a correction amount depending on a gap length is calculated using the selected calculation expression (S18, S19). Also, a transport distance is corrected using the correction amount (S20). Transport control is performed based on the transport distance (S21).SELECTED DRAWING: Figure 16

Description

  The present invention relates to a printing apparatus such as an ink jet printer and a print control program executed in the apparatus.

  Conventionally, as a type of printing apparatus, an ink jet printer that performs printing by ejecting ink, which is an example of liquid, from a print head that moves in a direction perpendicular to the medium conveyance direction with respect to a medium conveyed in a predetermined direction. Are known. In such a printer, since the ink ejected from the print head has inertia in the moving direction of the print head, the landing position of the ink on the medium is slightly displaced in the moving direction of the print head. Further, such a positional deviation varies depending on the degree of change when the distance between the surface of the medium and the print head changes. Therefore, in order to suppress the misalignment in such a case, a printing apparatus that controls the ejection timing for ejecting ink from the moving print head to the medium according to the difference in the distance between the surface of the medium and the print head is proposed. (For example, refer to Patent Document 1).

JP 2007-216480 A

  Incidentally, the displacement of the ink landing position that occurs when the print head moves while ejecting ink may also occur in the conveyance direction of the medium that intersects the movement direction of the print head. For example, when the print head moves, the print head pushes air in the moving direction and winds up, so that the landing position of the ink ejected from the print head due to the influence of the wind is in a direction parallel to the conveyance direction of the medium. Misalignment. This type of misregistration includes ink dots that are formed by landing ink ejected when the print head moved last time, and ink dots that are formed by landing ink ejected when the print head moved this time. A relative misalignment occurs between the two. In order not to deteriorate the print quality, it is desirable to suppress the relative positional deviation between dots due to such positional deviation in the transport direction.

  However, in this regard, Patent Document 1 only discloses a technique for suppressing the positional deviation that occurs in the movement direction of the print head by controlling the ejection timing, and the positional deviation of the landing position of the ink that occurs in the conveyance direction of the medium. There is no disclosure about the suppression technology. Further, even if the positional deviation of the ink landing position that occurs in the transport direction is allowed, there is no disclosure of a technique for suppressing a decrease in print quality due to the positional deviation.

  The present invention has been made in view of such circumstances, and an object of the present invention is to provide a printing apparatus capable of suppressing a decrease in print quality due to a displacement of a landing position of a liquid that occurs in a medium transport direction, and An object of the present invention is to provide a print control program executed in the printing apparatus.

Hereinafter, means for solving the above-described problems and the effects thereof will be described.
A printing apparatus that solves the above problems includes a conveyance unit that conveys a medium, a printing unit that performs printing by discharging liquid from a print head to the medium while moving in a direction that intersects the conveyance direction of the medium, and the printing A correction unit that corrects the conveyance amount of the medium with a correction amount corresponding to the size of the interval between the surface of the medium and the print head in the unit, and the medium with the corrected conveyance amount by controlling the conveyance unit And a control unit for transporting.

  According to this configuration, when printing is performed by ejecting liquid from the print head onto the medium transported to the printing unit by the transport unit, in the transport of the medium after the discharge of the liquid is finished while the print head is moving, The carry amount is corrected by a correction amount corresponding to the interval between the surface of the medium and the print head in the printing unit. Then, the medium is conveyed by the corrected conveyance amount. By the way, the amount of deviation of the landing position when the liquid ejected from the print head is flowed in the direction parallel to the transport direction in the process of flying the interval until it reaches the surface of the medium is determined by the strength of the wind. Under the same conditions, the larger the interval, the larger. As described above, even when the liquid landing position is shifted in the transport direction, the medium is transported by the transport amount after correction corrected by the correction amount corresponding to the size of the interval. As a result, before and after the medium is transported by the transport amount after correction, transport is performed between the print result (print dot group) when the print head was moved last time and the print result (print dot group) when it was moved this time. The relative positional deviation of the landed liquid (printing dots) generated in the direction can be suppressed to a small value. Therefore, it is possible to suppress a decrease in print quality due to this type of misregistration. For example, it is possible to reduce banding caused by an overlap or a gap between a print result obtained by the previous movement of the print head and a print result obtained by the current movement.

  In the printing apparatus, the correction unit includes an interval acquisition unit that acquires the size of the interval between the surface of the medium and the print head in the printing unit, and a correction amount corresponding to the size of the interval. It is preferable to include a correction amount acquisition unit that corrects the carry amount.

  According to this configuration, the size of the interval between the surface of the medium and the print head in the printing unit is acquired, and the conveyance amount of the medium is corrected with a correction amount corresponding to the acquired size of the interval. Therefore, even if the liquid ejected from the print head is caused to flow in the transport direction and the landing position thereof shifts in the transport direction, it is possible to suppress a decrease in print quality due to the positional shift in the transport direction.

  In the printing apparatus, the reference data in which the first gap amount, which is the size of the gap between the support unit that supports the medium, and the print head, and the thickness of the medium are individually associated with each piece of medium information is stored. The interval acquisition unit acquires medium information, refers to the reference data based on the medium information, and the first gap amount corresponding to the medium information and the thickness of the medium Is obtained, and the thickness of the medium is subtracted from the first gap amount to obtain a second gap amount that is the size of the gap between the surface of the medium and the print head.

  According to this configuration, the first gap amount and the medium thickness corresponding to the medium information are acquired by referring to the reference data based on the acquired medium information, and the medium thickness is subtracted from the first gap amount. Thus, the second gap amount that is the size of the interval between the medium and the print head is acquired. Therefore, the size of the interval (second gap amount) can be acquired based on the medium information acquired at the time of printing. The control unit can transport the medium by the corrected transport amount corrected by the correction amount according to the size of the interval.

  In the printing apparatus, the first reference data in which the first gap amount, which is the size of the gap between the support unit capable of supporting the medium and the print head, is individually associated for each of a plurality of types of medium information. And a storage unit that stores second reference data including a plurality of sets of set data in which the first gap amount and the correction amount are individually associated with each other, and the correction unit includes the acquired medium One first gap amount corresponding to the medium information is obtained by referring to the first reference data based on information, and another value having two values sandwiching the value of the first first gap amount Two set data including two first gap amounts and correction amounts corresponding to the other two first gap amounts are acquired from the second reference data, and interpolation using the two set data is performed. By calculating, the one first gap amount is It is preferable to obtain the correction amount.

  According to this configuration, the correction unit acquires one first gap amount according to the medium information with reference to the first reference data based on the acquired medium information, and the one first first Two sets of data including the other two first gap amounts having two values sandwiching the value of the gap amount and the correction amounts corresponding to the other two first gap amounts are obtained from the second reference data. The correction amount corresponding to one first gap amount is acquired by acquiring and performing interpolation calculation using two sets of set data. Therefore, it is possible to relatively easily acquire the correction amount corresponding to the first gap amount other than the first gap amount included in the set data while suppressing the number of set data stored in the storage unit.

In the printing apparatus, it is preferable that the correction unit corrects the carry amount with the correction amount when the control unit performs printing corresponding to band printing.
According to this configuration, when printing corresponding to band printing is performed, the length of a range in which a plurality of used nozzles are arranged in the medium transport direction in the print head (for example, the nozzle row length), or this length shorter than this length. The medium is greatly conveyed (largely fed) by a conveyance amount of a length close to that. Thus, during printing corresponding to band printing in which the medium is largely fed, the medium is conveyed by the conveyance amount corrected by the correction amount according to the interval. Banding due to the gap can be reduced.

  In the printing apparatus, when the moving speed of the print head is the first moving speed, the correction unit corrects the correction amount more than when the moving speed is the second moving speed that is slower than the first moving speed. Is preferably larger.

  According to this configuration, when the moving speed of the print head is the first moving speed, a stronger air current (wind) is likely to be generated than when the moving speed of the print head is slower than the second moving speed. The ejected droplets are more likely to flow in the transport direction due to the airflow. The amount of deviation of the landing position of the droplet in the transport direction due to the flow is determined according to the strength of the air flow, that is, the moving speed of the print head, and as the moving speed of the print head increases, the droplet flows in the transport direction. It becomes easy to be done. However, when the moving speed of the print head is the first moving speed, the transport amount is corrected with a correction amount that is larger than the correction amount corresponding to the second moving speed that is slower than the first moving speed. Banding and the like due to relative deviation from the printing result can be reduced.

In the printing apparatus, the correction unit may increase the correction amount when the interval is a second value wider than the first value than the correction amount when the interval is the first value. preferable.
According to this configuration, the correction amount when the second value is larger than the first value is larger than the correction amount when the size of the interval is the first value. Therefore, both in the case where the distance between the print head and the medium is the first value and the second value, the deviation of the liquid landing position in the transport direction can be reduced.

  In the printing apparatus, the print head is capable of ejecting droplets having different weights, and the correction unit is more effective than the first weight than a correction amount when ejecting droplets having the first weight. It is preferable to increase the correction amount when discharging a droplet having a light second weight.

  According to this configuration, the correction amount when discharging the second droplet having the second weight lighter than the first weight is smaller than the correction amount when discharging the droplet having the first weight. Become bigger. Therefore, even if the interval is the same, the transport amount is corrected by an appropriate correction amount according to the weight of the ejected droplets, so that the landing of the liquid does not depend on the difference in the weight of the ejected droplets. Deviation in the transport direction of the position can be suppressed more appropriately.

  The printing apparatus preferably includes a monochrome printing mode and a color printing mode as printing modes, and the correction unit preferably changes the correction amount between the monochrome printing mode and the color printing mode.

  According to this configuration, the specific gravity of the droplet differs between the monochrome printing mode and the color printing mode, for example, depending on the difference in the pigment or the dye in the droplet. The difference in specific gravity of the droplet affects the amount of deviation of the landing position in the transport direction when the droplet is flowed into the air stream. However, the correction amount is changed between the color printing mode and the monochrome printing mode. Therefore, even if the interval is the same, the transport amount is corrected with different correction amounts according to the monochrome printing mode and the color printing mode, so the liquid landing position in both the monochrome printing mode and the color printing mode. The shift in the transport direction can be suppressed more appropriately.

  In the printing apparatus, the correction unit is a correction amount when a liquid discharge amount rate representing a ratio of an actual total discharge amount to a maximum total discharge amount that can be discharged by one movement of the print head is a first rate. It is preferable to increase the correction amount when the second rate is higher than the first rate.

  According to this configuration, the first amount is higher than the correction amount when the liquid discharge rate representing the ratio of the actual total discharge amount to the maximum total discharge amount that can be discharged by one movement of the print head is the first rate. The correction amount when the second rate is higher than the rate is increased. By the way, the higher the liquid discharge rate, the more force is generated in the direction in which the discharged droplets are separated from each other, and the landing position of the liquid is displaced in the transport direction, but after correction corrected by the correction amount according to the liquid discharge rate Since the medium is transported by this transport amount, a decrease in print quality due to the positional deviation of the liquid landing position in the transport direction is suppressed.

  A printing control program that solves the above problems includes a conveyance unit that conveys a medium in a conveyance direction, a printing unit that performs printing by discharging liquid from a print head onto the medium while moving in a direction intersecting the conveyance direction, A printing control program to be executed by a computer in a printing apparatus including a control unit that controls the transport unit and the printing unit, the computer having the interval between the surface of the medium and the print head in the printing unit. A correction step of acquiring the size and correcting the transport amount of the medium by a correction amount corresponding to the size of the interval, and a control step of controlling the transport unit to transport the medium by the corrected transport amount And execute. According to this configuration, it is possible to obtain the same operation and effect as the above-described printing apparatus.

1 is a schematic side cross-sectional view showing a schematic structure of a printing apparatus. FIG. 3 is a block diagram illustrating a control configuration of the printing apparatus. The figure which shows the PLG table which shows the correspondence of medium information, the number of PLG steps, and the thickness of a medium. FIG. 3 is a schematic plan view of a medium printed by a normal band printing method. FIG. 6 is a schematic plan view showing an example in which white banding occurs in a printing result printed by a normal band printing method. FIG. 6 is a schematic plan view illustrating an example in which black banding occurs in a printing result printed by a normal band printing method. FIG. 6 is a schematic front view for explaining the influence of ink droplet wind when the distance between the print head and the medium is relatively narrow. FIG. 3 is a schematic front view illustrating the influence of ink droplet wind when the distance between the print head and the medium is relatively wide. FIG. 4 is a schematic side view showing a state where a medium being printed is positioned in an upper end region. FIG. 4 is a schematic side view showing a state where a medium being printed is located in a central region. FIG. 4 is a schematic side view showing a state where a medium being printed is located in a lower end region. The schematic side view explaining printing with respect to the medium located in a lower end area | region. The figure which shows the table data which show the relationship between PLG stage number and gap amount. The figure which shows the correction table referred when selecting the correction amount calculation formula according to various modes and the number of PLG steps. The graph which shows the relationship between gap amount and correction amount. The flowchart which shows a conveyance control processing routine. The flowchart which shows a correction amount calculation routine. The graph which shows the relationship between the gap amount and correction amount in a modification.

Hereinafter, an embodiment of a printing apparatus will be described with reference to the drawings.
As shown in FIG. 1, the printing apparatus 11 includes a substantially box-shaped housing 12, and in the housing 12, a transport unit 13 that transports a medium P such as paper along a transport path, and a transport unit. And a printing unit 14 that performs printing by discharging ink onto the medium P conveyed by the printer 13. In addition, a medium P to be fed one by one to the printing unit 14 is stacked in the cassette housing unit 16 that is recessed with a rectangular opening 15 in the front surface of the housing 12 in the lower part of the housing 12. A plurality of cassettes 17 that can be accommodated in a state are inserted through the front-side opening 15 so that they can be inserted and removed.

  In addition, an operation unit 18 composed of a liquid crystal panel or the like that is used when a user inputs or visually recognizes information related to printing to the printing apparatus 11 is provided on the upper front surface of the housing 12. . A hinge pin 19 extending in the horizontal direction is provided at a position below the operation unit 18 on the front surface of the housing 12, and a front cover 20 constituting a part of the front surface of the housing 12 is illustrated on the hinge pin 19. 1 is supported so that it can be opened and closed between a closed position indicated by a solid line and an open position indicated by a two-dot chain line.

  Further, on the front surface of the housing 12, between the lower end of the front cover 20 and the opening 15 of the cassette housing portion 16, the medium P on which an image or the like is printed by the printing unit 14 can be discharged to the outside of the housing 12. A discharge port 21 is provided. A discharge table 22 capable of supporting the medium P discharged from the discharge port 21 from below is disposed in the lower part of the discharge port 21 so as to be slidable forward in the discharge direction.

  In addition, a plate-shaped transport path constituting member 23 whose upper surface can constitute a part of the transport path of the medium P is provided at a position that is substantially the same height as the discharge table 22 and that is upper in the interior of the cassette housing portion 16. It has been. A lever member 24 is swingably supported on the conveyance path constituting member 23, and a feed roller 25 is rotatably supported on the lower end of the lever member 24. The feeding roller 25 is rotatable while being in contact with the upper surface of the uppermost medium P among a plurality of media P placed in a stacked state in the cassette 17, and is transmitted from a feeding motor (not shown). By rotating based on the driving force, the medium P is sent from the cassette 17 toward the separation slope 26 provided in the innermost part of the cassette housing portion 16. The separation slope 26 separates the media P one by one and guides them obliquely upward and rearward when the media P are fed from the cassette 17 by the feeding roller 25 in an overlapped state.

  As shown in FIG. 1, a retard roller 27 that is rotatable about an axis extending in the left-right direction is disposed at the upper end of the separation slope 26, and the retard roller 27 is positioned at a position obliquely above and in front of the retard roller 27. A large-diameter reversing roller 28 that can be driven to rotate with the medium P interposed between the roller 27 and the roller 27 is disposed. Further, around the reversing roller 28 in the housing 12, there are a plurality of conveying path constituting members 29 different from the conveying path constituting member 23 described above between the reversing roller 28 and between the conveying path constituting member 23 described above. The transport path for the medium P can be formed.

  Then, by the transport path constituting members 23 and 29 and the reverse roller 28, the casing 12 is sent from the separation slope 26 between the retard roller 27 and the reverse roller 28 and obliquely upward and rearward. A reversing path K1 for receiving and reversing the medium P and a printing path K2 for conveying the medium P received from the downstream end of the reversing path K1 to the printing unit 14 are formed. Further, in order to perform double-sided printing on the medium P that has been printed on one side by the printing unit 14, a return path K3 that can be returned and conveyed to the upstream end of the reverse path K1 through a path different from the print path K2 is provided in the vertical direction (FIG. 1). In the direction parallel to the Z direction) between the conveyance path constituting members 23 and 29 adjacent to each other. The transport unit 13 transports the medium P fed to the printing unit 14 in the transport direction F that intersects (especially orthogonal) with the scanning direction S through the reversing path K1, the print path K2, and the return path K3.

  In addition, a loading tray 30 on which the medium P can be loaded is provided at the rear upper end portion of the housing 12 so as to extend obliquely rearward and upward. A path that continues diagonally forward and downward from the lower end of the loading tray 30 is a merging path K4 with respect to the printing path K2, and this merging path K4 is located slightly downstream of the boundary position between the printing path K2 and the reversing path K1. It has joined K2. Furthermore, at the boundary position between the merging path K4 and the loading tray 30, the cross section D is rotated when the medium P placed on the loading tray 30 is sent to the merging path K4 and supplied to the printing path K2. A shaped delivery roller 31 is supported.

  In addition, as shown in FIG. 1, in the housing 12, a scanning direction that intersects (particularly orthogonally) the conveyance direction F of the medium P passes through the printing unit 14 that conveys the medium P from the printing path K <b> 2 of the conveyance unit 13. A guide shaft 32 extending along S is provided. A carriage 33 is supported on the guide shaft 32 so as to be movable in the scanning direction S along the guide shaft 32, and a print head 34 capable of ejecting ink is supported below the carriage 33. As illustrated in FIG. 6, a nozzle row including a plurality of nozzles 34 </ b> N is formed along the conveyance direction F of the medium P on the nozzle formation surface 34 a that is the lower surface of the print head 34.

  In the housing 12, a support base 35 capable of supporting the medium P conveyed to the printing unit 14 is located at a position facing the print head 34 (specifically, the nozzle forming surface 34 a) in the vertical direction. , Provided so as to extend along a direction parallel to the scanning direction S. The print head 34 ejects ink from the nozzles 34N of the nozzle forming surface 34a while moving in the scanning direction S with respect to the medium P conveyed to the printing unit 14 and supported on the back surface thereof by the support base 35. Thus, an image or the like is printed on the surface of the medium P.

  A holder portion 36 having a frame shape is provided at a position on the back side of the front cover 20 in the upper front portion of the housing 12, and the holder portion 36 includes a plurality of (this embodiment) containing different colors of ink. In the embodiment, four ink cartridges 37 are mounted. That is, in the present embodiment, a plurality of (for example, four) ink cartridges 37 that individually accommodate each of the four colors of black, cyan, magenta, and yellow have the holder portion in a state where the front cover 20 is in the open position. 36 is detachable. Then, each color ink is supplied from each ink cartridge 37 to the print head 34 through an individual ink supply tube 38.

  Further, as shown in FIG. 1, in the transport path of the medium P from the printing path K <b> 2 through the support base 35 to the discharge port 21 in the housing 12, the printing unit 14 (specifically, the support base 35. ), A first transport roller pair 39 is disposed on the upstream side, and a second transport roller pair 40 is disposed on the downstream side of the printing unit 14. The pair of transport rollers 39 and the pair of transport rollers 40 can transport the medium P in the transport direction F by rotating the pair of rollers up and down with the medium P sandwiched from both the front and back sides.

  Further, a substrate unit 41 is disposed in the housing 12 next to the holder portion 36, and a controller 45 is configured by the substrate unit 41. The board unit 41 is mounted with a computer 50 constituted by, for example, a one-chip microcomputer. The computer 50 performs operations of the transport unit 13 and the printing unit 14 in the printing apparatus 11 based on information input from the outside of the printing apparatus 11 through a communication line and information input from the operation unit 18 of the printing apparatus 11. Control.

Next, a control configuration in the printing apparatus 11 will be described.
As shown in FIG. 2, a computer 50 in the printing apparatus 11 includes a CPU 51 having a logical operation function as a central processing unit, a ROM for storing predetermined information in a readable manner, and various information in a readable / writable manner. It is configured as a digital computer including a storage unit 52 composed of a RAM or the like.

  When various types of information are input via an interface (not shown), the computer 50 performs various processes necessary for controlling processing procedures such as transport of the medium P by the printing apparatus 11 and printing on the medium P. A logical operation is performed, and various information used in the logical operation is read and written. The storage unit 52 stores various programs used to control the operating state of the printing apparatus 11.

  Of the various programs stored in the storage unit 52, the transport amount when the transport unit 13 transports the medium P based on the size of the interval between the surface of the medium P and the print head 34 at the time of printing. A print control program executed by the computer 50 for control is also included. Incidentally, the print control program is stored in a storage medium such as a memory card that can be inserted into a card insertion slot (not shown) provided in the printing apparatus 11 and read out from the storage medium as needed. Alternatively, it may be downloaded from the server when necessary via the Internet.

  As shown in FIG. 2, the operation unit 18 provided in the printing apparatus 11 is connected to the computer 50 in a state where input information based on the operation can be input, and the user owns the computer 50 as an external terminal, for example. A PC (personal computer) 53 is connected via a communication line so that data communication is possible. The PC 53 can cause the printing unit 14 to print a desired image or the like on the medium P based on the control of the computer 50 by transmitting print information to the computer 50. Further, during printing, the PC 53 can receive information indicating that printing is being performed from the computer 50.

  The computer 50 is connected to an encoder 54 and a medium sensor 55 so that detection signals detected by the respective sensors can be input. The encoder 54 is, for example, a rotary encoder that detects the amount of rotation of a roller that rotates in contact with the medium P when the medium P is conveyed to the printing unit 14 (for example, the rollers of the first conveying roller pair 39). The shaft is connected to the rotating shaft of the roller so as to be integrally rotatable. The medium sensor 55 detects the presence or absence of the medium P at the nearest position upstream of the printing unit 14 in the transport direction F. When the medium sensor 55 detects an end (front end or rear end) in the transport direction F of the medium P, The detection state (ON / OFF) is switched. For example, a detection position is defined between the first transport roller pair 39 and the support base 35, and a photo sensor or the like disposed at that position is used.

  As shown in FIG. 2, the computer 50 is connected to a plurality of drive units 56 to 59 that are driven by the printing apparatus 11. That is, a transport system drive unit 56 such as an electric motor that drives the transport unit 13, a carriage drive unit 57 such as an electric motor that drives the carriage 33, a head drive unit 58 that drives the print head 34 during printing, and a print head An interval adjustment drive unit 59 such as an electric motor driven when adjusting the size of the interval between the support 34 and the support base 35 is connected to the computer 50.

  The transport system drive unit 56 rotates each roller (for example, the drive roller of the transport roller pair 39, 40) constituting the transport unit 13 or stops its rotation by the computer 50 being controlled in rotation state. To do. The carriage driving unit 57 is controlled by the computer 50 so that the carriage 33 is driven and connected via a pulley or an endless belt so that the carriage 33 intersects (particularly orthogonally) the conveyance direction F of the medium P. It moves along the line 32 or stops its movement. Further, the head driving unit 58 applies a voltage to a piezoelectric element or the like that is driven when the print head 34 ejects ink based on the control of the computer 50, or stops the application of the voltage.

  Further, the interval adjusting drive unit 59 is moved in the vertical direction by a bearing member (not shown) of the guide shaft 32 that is drivingly connected via, for example, a pinion and rack mechanism, by the computer 50 controlling the rotation state. Or stop the movement. That is, when the electric motor of the interval adjusting drive unit 59 is rotationally driven, the rotational force is converted into a moving force in the vertical direction by the pinion and rack mechanism, and the bearing member of the guide shaft 32 by the moving force in the vertical direction. Also, the carriage 33 supported by the guide shaft 32 and the print head 34 supported by the carriage 33 also move in the vertical direction. Note that the direction in which the print head 34 moves by the interval adjustment drive unit 59 is such that the surface of the medium P supported by the support base 35 and the print head 34 move relative to each other in the opposite direction, and the interval between the two changes. If it is a direction to do, it will not be limited to an up-down direction.

  Through such control of the distance adjustment drive unit 59, the first gap amount Lpg and the support table, which are the size of the interval PLG between the print head 34 and the support table 35 (hereinafter also referred to as “first interval PLG”). The second gap amount x, which is the size of the interval PAG (hereinafter also referred to as “second interval PAG”) between the medium P supported on the print head 34 and the print head 34, can be adjusted. When the interval PLG (or PAG) is adjusted by the interval adjustment drive unit 59 as described above, the value of the interval PLG (or PAG) is temporarily stored in the storage unit 52. The second gap amount x, which is the size of the second interval PAG, is equivalent to the thickness LP of the medium P than the first gap amount Lpg, which is the size of the first interval PLG. The value is small.

  The CPU 51 in the computer 50 according to the present embodiment includes a plurality of functional units that perform various processes by performing data communication between the PC 53 and the operation unit 18. That is, the CPU 51 includes a control unit 60 and a data acquisition unit as functional units for correcting the conveyance amount of the medium P by the conveyance unit 13 based on the distance PAG between the surface Pa of the medium P and the print head 34 at the time of printing. 61, an interval acquisition unit 62, a determination unit 63, and a correction amount acquisition unit 64. In the present embodiment, the interval acquisition unit 62, the determination unit 63, and the correction amount acquisition unit 64 constitute an example of a correction unit.

  The control unit 60 controls the printing apparatus 11 in an integrated manner, and drives and controls the transport system driving unit 56, the carriage driving unit, the head driving unit 58, and the interval adjustment driving unit 59. The control unit 60 controls the transport amount of the medium P by drivingly controlling the transport system driving unit 56. Further, the control unit 60 controls the moving speed in the scanning direction S of the print head 34 mounted on the carriage 33 by controlling the driving of the carriage driving unit 57. Further, the control unit 60 controls the head drive unit 58 based on the print data during the scanning of the carriage 33 to discharge ink droplets from the nozzles 34N of the print head 34. A document or an image based on the print data is printed on the medium P by the dots that the ejected ink droplets land on the surface Pa of the medium P. Further, the control unit 60 controls the size of the interval PLG (first gap amount Lpg) between the print head 34 and the support base 35 by controlling the interval adjustment driving unit 59. In this example, by driving the interval adjustment drive unit 59, the first interval PLG is adjusted to a plurality of levels. The control unit 60 handles the multi-stage interval PLG by the number of PLG stages. The number of PLG stages is, for example, seven stages PLG1 to PLG7. As the step number of the interval PLG increases, the first gap amount Lpg increases stepwise.

  The data acquisition unit 61 acquires data such as print information (print condition information) input from the operation unit 18 at the time of printing, print information (print condition information) input from the PC 53, and the acquired data is used as necessary. To be stored in the storage unit 52. In addition to the image information representing the image printed on the medium P, the print information includes print mode information indicating print quality (standard, high definition) and print color (monochrome, color), and whether the printing method is single-sided printing. The discrimination information indicating the discrimination of double-sided printing and the media information regarding the type (medium type) of the medium P and the thickness LP are included. Further, the data acquisition unit 61 includes detection information including a number of pulses proportional to the conveyance amount of the medium P input from the encoder 54 during printing, and detection information when the medium sensor 55 detects the presence or absence of the medium P at the detection position. Is temporarily stored in the storage unit 52.

  The interval acquisition unit 62 acquires an interval PAG between the print head 34 and the surface Pa of the medium P. The interval PAG is also referred to as a paper gap when the medium P is a sheet. The interval acquisition unit 62 acquires the number of PLG steps that define the first gap amount Lpg and the thickness LP of the medium P based on the medium information included in the print information. Then, the interval acquisition unit 62 acquires the first gap amount Lpg corresponding to the number of PLG stages. Further, the interval acquisition unit 62 subtracts the thickness LP of the medium P from the first gap amount Lpg, thereby obtaining the second PAG that is the size of the interval PAG between the print head 34 and the surface P of the medium P on the support base 35. The gap amount x is obtained. Note that the interval acquisition unit only acquires the first gap amount Lpg and the thickness LP of the medium P, which is information necessary for acquiring the second gap amount x, and is a second difference that is the difference between the two. In some cases, the gap amount x is not acquired.

  The storage unit 52 stores the PLG table data TD1 shown in FIG. In the PLG table data TD1, the number of PLG steps and the thickness LP of the medium P are associated with each combination of medium type and medium size. The interval obtaining unit 62 refers to the PLG table data TD1 shown in FIG. 3 on the basis of the medium type and the medium size, and determines the number of PLG steps corresponding to the medium type and the medium size at that time and the thickness LP of the medium P. get. Then, when it is necessary to acquire the second gap amount x, the interval acquisition unit 62 subtracts the acquired thickness P of the medium P from the first gap amount Lpg corresponding to the acquired number of PLG steps, The second gap amount x is acquired. As shown in FIG. 3, the medium types to be printed by the printing apparatus 11 of the present embodiment include “plain paper”, “photo paper”, “envelope”, and the like. "A4 size", "A3 size", L size, 2L size, envelope standard size (for example, L1 × L2, L1 × L2), and the like. The medium thickness LP is set to, for example, “0.11 mm” for plain paper, “LP3”, “LP4”, “LP5”, etc. for photographic paper, “LP6”, “LP7”, etc. for envelopes.

  The determination unit 63 acquires various types of information necessary for correcting the transport amount from the various types of information acquired by the data acquisition unit 61, and makes various determinations based on the acquired various types of information. The determination unit 63 determines whether the carriage speed, which is the moving speed of the print head 34 at the time of printing, is high speed or low speed, determines whether the print color is monochrome or color, and the medium P being printed. It is determined whether the position is the normal area or the lower end area, whether the printing method is single-sided printing or double-sided printing, and whether the print quality is standard or high-definition.

  Of the two types of correction amounts ΔPF1 and ΔPF2 used for correcting the transport amount PF, the correction amount acquisition unit 64 is the latter used for reducing the positional deviation in which the landing position of the ink droplet shifts in the transport direction F due to the influence of wind. A correction amount ΔPF2 is acquired. The correction amount acquisition unit 64 of this example acquires the correction amount ΔPF2 by calculation using a predetermined calculation formula based on the second gap amount x. That is, the correction amount acquisition unit 64 selects one calculation formula according to the determination result of the determination unit 63, and the first gap amount Lpg acquired by the interval acquisition unit 62 based on the medium information is selected as the calculation formula. A correction amount ΔPF2 corresponding to the second gap amount x defined from the thickness LP of the medium P is calculated. The correction amount ΔPF2 is a function f (x) of the second gap amount x obtained by subtracting the thickness LP of the medium P from the first gap amount Lpg corresponding to the number of PLG stages determined from the medium information at that time. Represented.

  This function f (x) needs to be set individually for each printing apparatus 11. However, there are multiple types of parameters that determine the influence of wind, and measuring all the combinations of multiple types of parameters before shipment increases the amount of work. Therefore, as a value used for correcting the transport amount of the medium P, the thickness PPO of the medium P serving as a reference with respect to a predetermined number of PLG stages (that is, the first gap amount Lpg) set as a reference is set. Only a predetermined number of sets of data consisting of a combination of the first gap amount Lpg and the correction amount ΔPF2 serving as a reference in the case of “reference thickness LP0” is measured and stored in the storage unit 52.

  Then, the number of PLG steps applied to the current printing at the time of printing is obtained, and the combination of the two first gap amounts Lpg and the correction amount ΔPF sandwiching the value of the first gap amount Lpg corresponding to this PLG step number. Are selected, and interpolation calculation using the selected two sets of data is performed to calculate a correction amount ΔPF2 corresponding to the current number of PLG stages. Specifically, the first gap amount Lpg applied at the time of printing this time, the first gap amount Lpg (for example, X1 (see FIG. 14)) serving as a reference in one of the selected two sets, and the medium A difference dx (= Lpg−X1− (Lp−Lp0)) is acquired based on the information on the thickness LP of P and the reference thickness LP0. A correction amount difference dy is obtained based on the difference dx and the function f (x). A correction amount ΔPF2 (Y1 + dy) corresponding to the current second gap amount x1 is obtained by adding the correction amount difference dy to the reference correction amount Y1 in one set of data.

  In the present embodiment, the second gap amount x is not obtained, and information about the number of PLG stages, the thickness P of the medium P, and the reference thickness LP0, which are control parameters of the printing apparatus 11, and a part of the reference. Based on correction table data TD3 including set data corresponding to the number of PLG stages, a correction amount ΔPF2 corresponding to the second gap amount x is acquired. In this example, a graph line represented by a curved function representing the relationship between the second gap amount x and the amount of deviation of the landing position of the ink droplet in the transport direction F due to the influence of wind is a straight line or a broken line. Use approximate linear functions. Then, a plurality of types of linear functions (y = f (x) = ax + b) are used as a calculation formula for obtaining the correction amount ΔPF2 corresponding to the second gap amount x (see FIG. 15).

  The printing unit 14 prints an image or the like on the medium P based on the control by the computer 50 as described above. As a printing method of this kind, an image corresponding to the length of the nozzle array of the nozzles 34N (see FIG. 7 and the like) in the print head 34 is printed by one movement (scanning) of the carriage 33, and then the nozzle array There is a printing technique called band printing (hereinafter referred to as “normal band printing”) in which the medium P is transported in the transport direction F by the length, and thereafter, printing of the same image and transport of the medium P are repeated. In the printing apparatus 11 according to the present embodiment, when the print information input from the operation unit 18 or the print information input from the PC 53 includes command information for normal band printing, the control unit 60 includes the transport unit 13 and the control unit 60. The printing unit 14 is controlled to perform normal band printing.

  As shown in FIG. 4, in normal band printing, the first image GR1 having an image length GL corresponding to the length of the nozzle row is printed on the medium P after the first conveyance of the medium P having the conveyance amount PF1. Then, a second image GR2 having the same image length GL as that of the first image GR1 is printed on the medium P after the second conveyance of the medium PF2. Then, a third image GR3 having the same image length GL as the first image GR1 and the second image GR2 is printed on the medium P after the third conveyance amount PF3 of the medium conveyance.

  In this case, if the first transport amount PF1, the second transport amount PF2, and the third transport amount PF3 are equal, as shown in FIG. 4, the first image GR1, the second image GR2, and the third time The image GR3 is not printed with a gap formed between adjacent images in the transport direction F or printed partially overlapping. However, in such normal band printing, if there is a difference in the transport amount for each scan, adjacent images may form a gap or partially overlap between the two images.

  That is, as shown in FIG. 5, in normal band printing, the first transport amount PF1 is equal to the second transport amount PF2, but the third transport amount PF3 is larger than the transport amounts PF1 and PF2. A white banding area WA that appears white with a gap between the second image GR2 and the third image GR3 is formed.

  As shown in FIG. 6, in normal band printing, the first transport amount PF1 is equal to the second transport amount PF2, but the third transport amount PF3 is smaller than the transport amounts PF1 and PF2. The second image GR2 and the third image GR3 partially overlap to form a black banding area KA that is printed in a black belt shape.

  By the way, as shown in FIG. 7, for example, in normal band printing, the conveyance direction F (the direction indicated by the white arrow in the figure) is equal to the conveyance amount PF corresponding to the length of the nozzle row formed by a large number of nozzles 34N on the nozzle formation surface 34a. ) Is intermittently conveyed, but the conveyance amount PF at that time may not match the image length GL of the image formed on the medium P. For example, the ink INC discharged from the print head 34 due to the influence of the wind generated when the carriage 33 and the print head 34 move in a direction intersecting the conveyance direction F of the medium P (a direction orthogonal to the paper surface in FIG. 7). May be displaced in the transport direction F of the medium P, and the image length GL of an image formed on the medium P may be larger than the transport amount PF. Further, in the process of moving the print head 34, an air flow flows into a gap of a kind of ink droplet curtain formed by the ink droplets ejected from the nozzles 34 </ b> N adjacent between the nozzle rows in the print head 34, thereby causing the ink droplets. Spread outward in a direction parallel to the transport direction F. In this case, each landing position of the ink INC is displaced so as to spread in a direction parallel to the transport direction F of the medium P, and the image length GL of the image formed on the medium P becomes larger than the transport amount PF. There is.

  Further, as shown in FIG. 8, the difference between the transport amount PF and the image length GL generated in such a case is the difference between the surface Pa of the medium P supported on the support base 35 and the nozzle formation surface 34a of the print head 34. It changes according to the size of the interval PAG (for example, paper gap). The size of the second interval PAG is obtained by subtracting the thickness LP of the medium P from the size of the first interval PLG (second gap amount). In the example of FIGS. 7 and 8, since the first interval PLG and the second interval PAG are larger in the case of FIG. 8 than in the case of FIG. 7, the difference between the transport amount PF and the image length GL is also large. 8 is larger than that in FIG.

  For this reason, in the present embodiment, by correcting the transport amount PF according to the image length GL, even if the landing position of the ink droplet is shifted in the transport direction F due to wind, It is possible to suppress relative displacement between the print result and the current print result in the transport direction F. As a result, banding due to an overlap or gap between the previous print result and the current print result is reduced. As shown in FIGS. 7 and 8, in the normal band printing method, the used nozzles used for discharging the ink INC among all the nozzles 34N in which the transport amount PF is arranged at a constant nozzle pitch along the transport direction F. Large feed is performed at a transport amount corresponding to the total number of nozzles 34N (for example, the total number of nozzles nm (where m is, for example, 2 to 10)) or the total nozzle pitch length of a few minutes. In addition to normal band printing, there is an irregular band printing method (also referred to as “microfeed printing method”) as a printing method in which this type of large-feed intermittent conveyance is performed.

  In normal band printing, the medium P is intermittently conveyed at a predetermined distance equal to the accumulated length (total nozzle pitch length) of all the nozzle pitches of all the used nozzles 34N of the print head 34, and printing is performed between the intermittent conveyances. This is a printing method in which ink is ejected from the head 34 for printing. On the other hand, irregular band printing means that the medium P is intermittently transported (minute feed) at a minute distance equal to (0.5 × J) times the nozzle pitch (where J is an odd number), and the cumulative length of all nozzle pitches (total This is a printing method in which ink is ejected from the print head 34 during intermittent conveyance while alternately performing intermittent conveyance (large feed) at a distance close to the cumulative length below (nozzle pitch length).

  Here, the transport amount PF shown in FIGS. 7 and 8 is obtained by correcting the set transport amount PFo determined based on the print mode and print data with the transport system correction amount ΔPF1 in the case of normal band printing and irregular band printing. (PF = PFo + ΔPF1). The transport system correction amount ΔPF1 includes a correction amount ΔPF11 caused by an error in the roller diameters of the transport roller pair 39, 40 and a correction amount ΔPF12 considering the slip amount between the medium P and the transport roller pair 39, 40. . In this embodiment, the transport amount PF (= PFo + ΔPF1) corrected for the transport system is transported by the correction amount ΔPF2 for reducing the amount of deviation of the ink droplet landing position in the transport direction due to the influence of wind. By correcting the PF, the corrected transport amount PFa (= PFo + ΔPF1 + ΔPF2) is acquired.

  Here, the following may be cited as factors that cause the ejected ink droplets to flow in the wind and the landing position to shift in the transport direction F. That is, the carriage speed Vcr, the size of the space in the machine, the size of the interval PAG between the print head 34 and the surface Pa of the medium P (second gap amount), the ink droplet ejection speed Vm, and the print head 34 once. Ink discharge rate (printing duty) (%), ink weight (or ink density) per movement (scan).

  As the carriage speed Vcr increases, the volume of air that the carriage 33 pushes away per unit time increases, so that a stronger air current is generated. The narrower the space in the machine, the higher the flow rate of the airflow generated by the air that is pushed away when the carriage 33 moves, and thus a stronger wind is generated. The larger the interval (second gap amount), the longer the dwell time (flying time) that is caused to flow by the air current until the ink droplets land on the surface Pa of the medium P. The longer the time, the longer the ink droplets. The amount of deviation of the landing position in the transport direction F increases. The ejection velocity Vm is the initial velocity of the ink droplet ejected from the nozzle 34N, and the velocity during the flight of the ink droplet is approached from the ejection position to the landing position due to the air resistance that the ink droplet receives during the flight. Decrease gradually. For this reason, the lower the ejection speed Vm, the longer the time for which the ink droplets land on the surface Pa with a predetermined gap, and the greater the amount of displacement of the ejected ink drops in the transport direction F. .

  The ink discharge rate (print duty) (%) indicates the ratio of the actual total discharge amount to the maximum total discharge amount that can be discharged using all the used nozzles 34N by one movement of the print head 34. The ink ejection rate is, for example, “100%” when large dot ink droplets are ejected from all the nozzles 34N, and “50%” when large dot ink droplets are ejected from half of the nozzles 34N. Furthermore, even if ink droplets are ejected from all the nozzles 34N, if the ejected ink droplet is a medium dot, the ink ejection rate is, for example, “50%”, and if the ejected ink droplet is a small dot, The ink discharge rate is, for example, “20%”. When the ink droplets are ejected from all the nozzles 34N all at once, a force is generated in which the adjacent ink droplet rows belonging to the adjacent nozzle row repel each other due to the momentum of the respective ejection flows. For this reason, the plurality of rows of ink droplets ejected from the print head for each nozzle row spread in a fan shape from the center to the outside in the transport direction of the print head 34 due to the repulsive force of each other (FIGS. 7 and 8). Here, each time the carriage 33 acquires the print data for one pass in which the carriage 33 moves once in the scanning direction S, the control unit 60 analyzes the print data for the one pass and acquires the ink discharge rate. The ratio (%) of the number of ejection pixels among all the pixels (all dots) is obtained by weighting the pixel size (large / medium / small) of the ejection pixels.

  The larger the ink weight (or ink density), the less affected by the wind, the smaller the deviation amount of the landing position, and the smaller the correction amount for correcting the deviation amount, the smaller the ink weight. In other words, the correction amount when the weight of the ink droplet is the first weight may be larger than the correction amount when the second weight is heavier than the first weight. Here, the modes with different ink drop weights include a color printing mode that defines a printing color in one mode and a monochrome printing mode, and the other one is a standard printing that defines an ink droplet size (dot size). Mode and high-definition printing mode. The latter mode for defining the print quality may be divided into three stages of low quality, standard, and high definition. The black ink used in the monochrome printing mode includes a black pigment or dye, and the color ink used in the color printing mode includes, for example, pigments or dyes of CMY colors. For this reason, since the specific gravity and content of the pigment or dye contained in the ink differ depending on whether it is monochrome printing or color printing, the ink density is different. If the ink droplet size is the same, the higher the ink density, the heavier the ink weight, the less affected by the wind, and the smaller the correction amount.

  In the present embodiment, the print head 34 can eject ink droplets of different sizes from the nozzle 34N. In this example, ink droplets can be ejected in a total of three types, for example, a large size, a medium size, and a small size. In the normal printing mode, ink droplets are ejected in two types of large and medium sizes, and in the high quality printing mode, ink droplets are ejected in two types of medium size and small sizes. Here, assuming that the ink specific gravity is constant, in the normal printing mode, the average size of the ink droplets is relatively large and the average weight of the ink droplets is also relatively large. On the other hand, in the high quality printing mode, since the average size of the ink droplets is relatively small, the average weight of the ink droplets is also relatively small. For this reason, the correction amount is increased as the print quality is higher, in which smaller (lighter) ink droplets are used in average size.

  Next, how to select the first interval PLG will be described. Here, the computer 50 in the printing apparatus 11 uses the combination of the medium type (for example, paper type) and the medium size (for example, paper size) included in the printing condition information input together with the print command, and the PLG table data TD1 shown in FIG. Each information of one PLG stage number and the thickness of the medium P is acquired. Further, the control unit 60 corrects the previously selected PLG stage number in accordance with the combination of the print mode (standard / high definition) and the single-sided / double-sided discrimination information included in the print information.

  When one PLG stage number is thus determined, the interval acquisition unit 62 refers to the table data TD2 shown in FIG. 13 based on the PLG stage number, and acquires a gap amount Lpg (mm) corresponding to the PLG stage number. The interval acquisition unit 62 acquires the first gap amount Lpg, which is the size of the interval PLG between the print head 34 and the support surface 35a, and the thickness LP of the medium P, and if necessary, the difference between the two. Is obtained, the second gap amount x (= Lpg−LP), which is the gap amount of the interval PAG (for example, paper gap) between the print head 34 and the surface Pa of the medium P, is obtained.

  For example, as the print mode, the number of PLG stages having a larger gap amount is selected in the high-definition print mode than in the standard print mode. This is because the amount of ink landed per unit area of the medium P is relatively large in the high-definition mode so that the print head 34 can avoid rubbing on the medium P swollen by the ink absorbed by the medium P. In the high-definition printing mode, the number of PLG stages having a wider gap than in the standard printing mode is selected.

  For the printing surface designation information for double-sided printing / single-sided printing, a wider PLG stage number is selected for double-sided printing than for single-sided printing. This is because in double-sided printing, the medium P absorbs ink and swells when the surface (one side) is printed, and it is relatively easy to curl, so that the print head 34 is not rubbed against the medium P. It is. For this reason, at the time of double-sided printing, the number of PLG stages at which a gap amount wider than the gap amount at the time of single-sided printing is selected at least during back-side printing. In this example, during double-sided printing, the same number of PLG stages larger than the number of PLG stages during single-sided printing is selected without distinguishing between the front and back surfaces. Note that the same number of PLG steps as in single-sided printing may be used during front side printing in double-sided printing, and a larger amount of PLG steps may be selected during backside printing than during single-sided printing.

  Further, in the printing apparatus 11, the user can operate the operation unit 18 to select validity / invalidity of the rubbing prevention function. When the computer 50 receives an input signal for enabling the rubbing prevention function from the operation unit 18, the computer 50 selects the number of PLG stages that can obtain a gap amount larger than the gap amount when the function is invalid. As described above, in this example, the number of PLG stages determined by referring to the PLG table data TD1 shown in FIG. 3 based on the medium information, the discrimination information for single-sided printing / double-sided printing, the invalid / valid information of the anti-friction function, and Based on the above, when the double-sided printing and the rubbing prevention function are effective, the number of PLG steps is changed to obtain a larger gap amount.

  Next, with reference to FIGS. 9 to 12, three types of regions where the medium P is positioned during printing will be described. In the conveyance process, the medium P is supported at two locations by the upper end region shown in FIG. 9 where the leading end (upper end) in the conveyance direction of the medium P is located between the conveyance roller pairs 39 and 40 and the medium P by the conveyance roller pairs 39 and 40. 10 and the lower end region shown in FIG. 11 in which the rear end (lower end) in the conveyance direction of the medium P is located between the conveyance roller pairs 39 and 40 are sequentially taken.

  As shown in FIG. 9, when the medium P is located in the upper end region, the upper end portion of the medium located between the transport roller pairs 39 and 40 is supported only by the upstream transport roller pair 39, The upper end portion extends along the support surface 35 a of the support base 35 with the tension of the medium P. On the other hand, as shown in FIG. 10, when the medium P is located in the central region, the central portion of the medium P is supported (clamped) at two locations on both sides by the transport roller pairs 39 and 40, so This portion is not lifted up and is supported along the support surface 35a of the support base 35.

  Further, as shown in FIG. 11, when the medium P is positioned in the lower end region, the lower end portion of the medium P positioned between the transport roller pairs 39 and 40 is supported only by the downstream transport roller pair 40. is there. At this time, the portion where printing has already been completed on the downstream side in the transport direction from the lower end portion of the medium P is likely to curl due to swelling due to ink absorption, and the lower end portion is likely to be lifted from the support surface 35a.

  As shown in FIG. 12, when the lower end portion of the medium P is lifted obliquely at an angle θ, for example, it is indicated by a two-dot chain line as compared with the width L1 in the transport direction F of the ink landing range for the medium P indicated by a solid line that is not lifted. The width L2 of the ink landing range for the lifted medium P shown is longer. For this reason, in the present embodiment, when the upper region and the central region are combined into a normal region, the transport amount correction when the medium P is in the lower region is more than the transport amount correction amount when the medium P is in the normal region. The amount is larger.

  Here, the control unit 60 counts the number of pulses of the pulse signal input from the encoder 54 based on the position of the medium P when the medium sensor 55 detects the leading edge of the medium P, and based on the counted value. The transport position of the medium P is managed. Then, the determination unit 63 includes a transport position of the medium P managed by the control unit 60, a first range representing a transport position range when the medium P is in the normal area, and a case where the medium P is in the lower end area. It is compared with the second range representing the range of the transport position to determine whether the medium P belongs to the normal area or the lower end area.

  In the present embodiment, in order to reduce or eliminate the white banding area WA shown in FIG. 5 and the black banding area KA shown in FIG. 6, the transport amount PF of the medium P is set to the first gap amount corresponding to the number of PLG steps at the time of printing. Correction is performed in accordance with the second gap amount x determined from Lpg and the thickness LP of the medium P. The storage unit 52 stores table data TD1 to TD3 shown in FIGS. 3, 13, and 14 that are used by the computer 50 to correct the carry amount during printing.

  First, the table data TD2 shown in FIG. 13 is a table showing the relationship between the number of PLG stages and the gap amount Lpg. As an example, a gap amount Lpg is shown for each number of PLG stages including a total of seven stages of PLG1 to PLG7. The unit of the gap amount Lpg is [0.01 mm]. For example, the gap amount “130” of PLG1 means that the interval between the support surface 35a of the support base 35 and the nozzle formation surface 34a of the print head 34 is “130” × [0.01 mm] = 1.3 mm.

  On the other hand, the correction table data TD3 shown in FIG. 14 is table data in which various data for determining coefficients and constants of calculation formulas used when calculating the correction amount for each print color mode, transport area, and number of PLG stages are set. The correction table data TD3 includes a primary value used when calculating a correction amount ΔPF2 corresponding to the gap amount x for each print color mode, each conveyance region, each print speed mode (carriage speed Vcr), and each PLG stage number. A slope calculation setting value is set to determine the slope of the straight line (that is, the coefficient in the calculation formula) in which the formula of the function is represented in a graph (see FIG. 15). The print color mode is divided into a monochrome print mode and a color print mode. In addition, the transport area is divided into a normal area and a lower end area. The printing speed mode is divided into high speed and low speed. Furthermore, the number of PLG stages is divided into three ranges of PLG1 to PLG3, PLG4 to PLG5, and PLG6 to PLG7.

  In the graph of the linear function representing the calculation formula shown in FIG. 15, the X-axis shows the gap amount x (however, in the example of FIG. 15, the gap amount (x + LP0)), and the Y-axis shows the correction amount ΔPF2. The slope calculation setting values (Y1, Y2, X1, X2) shown in FIG. 14 are the coordinates (X1, Y1) of two points serving as a reference on the straight line that defines the slope of the straight line (FIG. 15) of the linear function. , (X2, Y2). Note that PLG1 to PLG5 are used in a high-speed printing mode that is set when normal band printing and irregular band printing are performed on a relatively thin first medium such as plain paper or photographic paper. One PLG6 to PLG7 is used in a low-speed printing mode that is set when normal band printing and irregular band printing are performed on a relatively thick second medium such as an envelope. Hereinafter, normal band printing and irregular band printing are referred to as “printing corresponding to band printing”, and are simply referred to as “band printing”.

  For example, when the printing mode is monochrome printing and the PLG stage number is PLG4, the gap amount x is a value within the range of “190 (X1)” to “255 (X2)”, and the gap amount x is “190 ( The correction amount in the case of “X1)” is “H3BK (Y1)”, and the correction amount in the case of the gap amount “255 (X2)” is “H4BK (Y2)”. The set value of the correction table data TD3 is obtained by changing each parameter (carriage speed, print color, transport area) using plain paper with a reference thickness LP0 for the reference PLG stage number before shipment of the printing apparatus 11. This is obtained from the measurement result of the shift amount in the transport direction F based on the printing result of the test printing performed by the printing method. In the correction table data TD3, the relationship between the correction amount ΔPF (Y1, Y2) obtained from the measurement value of the deviation amount of the print result of the test printing and the gap amount Lpg (X1, X2) of the reference PLG stage number is printed. This is expressed for each color (mode) and conveyance area (normal / lower end).

  In the correction table data TD3 shown in FIG. 14, the setting values for slope calculation (Y1, Y2, X1, X2) = (H1BK, H3BK, 130, 190) corresponding to the PLG stage number “1 to 3” are, for example, the PLG stage number. Is used to specify the calculation formula when “1” to “3”. The inclination calculation setting values (Y1, Y2, X1, X2) indicate the coordinates (X1, Y1) and (X2, Y2) of the two ends of the straight line (FIG. 15) representing the linear function. The correction amount ΔPF corresponding to the number of PLG steps between these two points is calculated by interpolation calculation using the coordinates of these two points.

  The graph shown in FIG. 15 shows the relationship between the gap amount Lpg corresponding to the number of PLG steps and the correction amount ΔPF2 when printing corresponding to band printing is performed using the medium P having the reference thickness LP0 (for example, 0.11 mm). The calculation formula of the linear function shown is graphed. Therefore, the X-axis is the gap amount Lpg when applied to the medium having the reference thickness LP0, that is, the gap amount (x + LP0). When this graph is shifted in the minus X direction by the reference thickness LP0 (= 0.11 mm), a graph of a linear function with the X axis as the gap amount x is obtained. In this example, the calculation formula is specified by a graph showing the relationship between the gap amount Lpg of the number of PLG steps and the correction amount ΔPF2 using the value of the measurement result before shipment of the printing apparatus 11, but the above-described gap A calculation function of a linear function indicating the relationship between the amount x and the correction amount ΔPF2 may be used.

  In FIG. 15, a graph A when the number of PLG stages is PLG1 to PLG3 and PLG4 to PLG5 is a high speed that is a first movement speed in which the movement speed (carriage speed Vcr) of the carriage 33 on which the print head 34 is mounted is relatively fast. It is a graph in the case of a printing mode. On the other hand, a graph B when the number of PLG stages is PLG6 to PLG7 is a graph in the case of the low-speed printing mode in which the moving speed of the carriage 33 on which the print head 34 is mounted is the second moving speed that is slower than the first moving speed. It is. As an example, the first moving speed in the high-speed printing mode is 360 cps, which advances 360 inches per second. The second moving speed in the low-speed printing mode is 180 cps, which is advanced by 180 inches per second as an example.

  The reason why the low-speed printing mode is applied when the number of PLG stages in the graph B is PLG6 to PLG7 is as follows. The larger the gap amount, the longer the time for the ink droplets ejected from the print head 34 to land on the surface Pa of the medium P. That is, the shift amount becomes longer. Therefore, the amount of deviation of the landing position of the ink droplets in the transport direction F is suppressed to be small by weakening the wind generated by relatively slowing down the carriage speed Vcr. As understood from the graph A and the graph B in FIG. 15, generally, the larger the gap amount x, the larger the correction amount ΔPF2 used for correcting the carry amount due to the influence of the wind. However, by applying the low-speed printing mode, It is possible to keep the correction amount ΔPF2 small compared with the case where the high-speed printing mode is applied.

  Next, a conveyance control process performed when the computer 50 executes a print control program in the printing apparatus 11 according to the present embodiment will be described with reference to FIGS. 16 and 17. When a printing command is received from the operation unit 18 and the PC 53 together with printing information, the computer 50 of the printing apparatus 11 first drives the transport system driving unit 56 to set the medium P set in a designated feeding source (for example, the cassette 17). Is fed to the printing unit 14. The medium P is fed to the printing start position. Thereafter, the computer 50 drives and controls the carriage drive unit 57 so that the print head 34 moves (scans) in the first scanning direction S, and drives and controls the head drive unit 58 during the movement. By ejecting ink droplets from the print head 34, printing for one pass (one line) by the first scanning is performed. Then, the first intermittent conveyance of the medium P is performed. This routine is executed prior to the first intermittent conveyance. During printing by the printing apparatus 11, the computer 50 performs printing for one movement (one pass) of the print head 34 by driving and controlling the carriage driving unit 57 and the head driving unit 58, and driving of the conveyance system. The intermittent conveyance of the medium P by driving and controlling the unit 56 is alternately performed. This routine is executed by the computer 50 every time the medium P is intermittently conveyed. When receiving a print command, the data acquisition unit 61 of the computer 50 temporarily stores the print information input from the operation unit 18 and the PC 53 in the storage unit 52.

  When this routine is started, in step S11, the computer 50 determines whether or not the printing method for the medium P to be performed is band printing. That is, does the determination unit 63 of the computer 50 include information on printing input from the operation unit 18 and print information input from the PC 53 including normal band printing or irregular band printing command information belonging to band printing? Judge whether or not. If it is determined that the band printing command information is not included (S11 = NO), the computer 50 ends this routine.

  On the other hand, if it is determined that the band printing command information is included (S11 = YES), the transport amount PF is acquired in the next step S12. That is, the control unit 60 of the computer 50 sets the transport amount PF based on the image information for the next one scan included in the print information and the feed rule applied to the next pass according to the printing method at that time. decide.

  In the next step S13, the computer 50 determines whether or not the intermittent conveyance of the medium P to be performed in the future is so-called large feed that is intermittently conveyed at a conveyance distance close to the length of the nozzle row. That is, in the case of normal band printing, since all intermittent conveyance is basically large feed, it is determined as “large feed” in every intermittent scan. In the case of irregular band printing, since minute feed and large feed are alternately performed, it is determined as “large feed” only at times corresponding to large feed. If it is determined that the transport mode is not so-called large feed (S12 = NO), the computer 50 ends this routine.

  On the other hand, when it is determined that the current intermittent conveyance is large feed (S12 = YES), in the next step S14, the computer 50 acquires the number of LPG stages and the thickness LP of the medium. That is, the interval obtaining unit 62 obtains medium information from the print information temporarily stored in the storage unit 52 by the data obtaining unit 61 when a printing command is received, and the medium type and medium size included in the medium information. Based on the above, the PLG table data TD1 shown in FIG. 3 is referred to and the PLG stage number and the medium thickness LP are obtained. Thus, information on the number of PLG stages and the thickness LP corresponding to the combination of the medium type (plain paper, glossy paper, envelope, etc.) and the medium size (A4 size, A3 size, envelope rated size, etc.) is acquired. Further, the interval acquisition unit 62 calculates the thickness of the medium P from the gap amount Lpg (mm) which is the size of the corresponding first interval PLG acquired with reference to the table data TD2 shown in FIG. By subtracting LP, the second gap amount x (= Lpg−LP), which is the size of the second interval PAG, is acquired.

  In the next step S15, the computer 50 determines the carriage speed Vcr. In this example, in band printing, the carriage speed Vcr (that is, the moving speed of the print head 34) is varied depending on the medium type. That is, when the medium type is the first medium having a relatively small thickness, such as plain paper or photographic paper, the high-speed printing mode is applied, and the second medium type having a relatively large thickness, such as an envelope, is applied. If it is a medium, the low-speed printing mode is applied. The determination unit 63 acquires a printing speed mode to be applied based on the medium type information, and acquires a carriage speed Vcr corresponding to the acquired printing speed mode. For example, when the medium is a first medium such as plain paper or photographic paper, the carriage speed Vcr is determined as a relatively high first moving speed (for example, 360 cps), and when the second medium type is an envelope or the like, The carriage speed Vcr is determined to be a second movement speed (for example, 180 cps) that is lower than the first movement speed. The computer 50 temporarily stores the determination result of whether the carriage speed Vcr is high or low in the storage unit 52, and then proceeds to the next step S16.

  In the next step S <b> 16, the computer 50 determines the color used for printing at the time of the current printing. That is, the determination unit 63 determines whether the current print mode is monochrome printing or color printing. This determination is also made based on print information input from the operation unit 18 and the PC 53. The computer 50 temporarily stores the determination result in the storage unit 52, and then proceeds to the next step S17.

  In the next step S <b> 17, the computer 50 determines the conveyance area of the medium. That is, the determination unit 63 determines whether the transport position of the medium P being printed belongs to the normal area or the lower end area. The determination unit 63 includes a transport position of the medium P managed by the control unit 60, a first range representing a transport position range when the medium P is in the normal area, and a transport position when the medium P is in the lower end area. Is compared with the second range representing the above range, and it is determined whether the medium P is in the normal region or the lower end region. The computer 50 temporarily stores the determination result in the storage unit 52, and then proceeds to the next step S18.

  In the next step S18, the computer 50 selects a calculation formula corresponding to the carriage speed, the print color, and the transport area. The calculation amount is selected by the correction amount acquisition unit 64. As shown in FIG. 15, in the high-speed printing mode in which the carriage speed Vcr is high, the correction amount acquisition unit 64 selects a calculation formula in the graph A, and prints colors (monochrome / monochrome) from the graph A. The calculation formula represented by one graph is selected according to the condition of (color) and the condition of the transport area (normal area / lower end area) to which the transport position of the medium P belongs.

  In the next step S19, the computer 50 calculates a correction amount according to the gap amount using the selected calculation formula. In this process, the correction amount acquisition unit 64 calculates the correction amount ΔPF2 corresponding to the second gap amount x based on the calculation formula f (x) represented by the function of the second gap amount x. Specifically, the computer 50 executes the correction amount calculation routine shown in FIG. Details of the processing contents of the correction amount calculation processing routine will be described later.

  In the next step S20, the computer 50 corrects the carry amount. That is, the control unit 60 corrects the transport amount PF with the correction amount ΔPF2 acquired by the correction amount acquisition unit 64. In the present embodiment, each process of steps S14 to S20 corresponds to an example of a correction step.

  In the next step S21, the computer 50 transports the medium by the transport amount PF. That is, the control unit 60 drives and controls the transport system driving unit 56 and transports the medium P by the transport amount PF by the rotation of the transport roller pairs 39 and 40. By this intermittent conveyance, the medium P is conveyed to the next printing position. At this time, when the transport amount is corrected in step S20, the control unit 60 controls the transport system driving unit 56, and the medium P is transported by the corrected transport amount. In the present embodiment, the process of step S21 corresponds to an example of a control step.

  Next, the correction amount calculation routine will be described with reference to FIG. This correction amount calculation routine is executed by the correction amount acquisition unit 64 of the computer 50. Note that before starting this routine, the interval acquisition unit 62 determines the number of PLG stages to be applied to the current printing and the thickness LP of the medium P. Also, the current printing color mode (monochrome printing / color printing), the transport area to which the current transport position of the medium P belongs, the print speed mode (high speed / low speed) that defines the moving speed (carriage speed Vcr) of the print head 34, and the like. Has also been determined. Each of the determined information is temporarily stored in the storage unit 52.

  First, in step S31, inclination calculation setting values Y1, Y2, X1, and X2 corresponding to the print color, the conveyance area, the carriage speed, and the number of PLG steps are acquired. That is, the correction amount acquisition unit 64 selects the print color mode (monochrome / color), the transport area (normal / lower end), the print speed mode (high speed / low speed), and the number of PLG steps (PLG 1 to 7) applied to the current printing. Read from the storage unit 52, and reference to the correction table data TD3 shown in FIG. 14 based on these parameters, the inclination calculation setting values Y1, Y2, X1, X2 are obtained.

In the next step S32, a gap amount difference dx is calculated. That is, the correction amount acquisition unit 64 calculates the difference dx by the following equation (1).
dx = Lpg-X1- (Lp-Lp0) (1)
Here, Lpg is a gap amount (mm) according to the number of PLG steps applied to the current printing, X1 is an X reference coordinate according to the current number of PLG steps, and Lp is the thickness of the medium P to be printed this time ( mm), Lp0 is a reference thickness (for example, 0.11 mm) of the medium P (for example, plain paper) used for test printing before product shipment. This difference dx corresponds to the difference between the gap amount x0 (= X1-LP0) at the reference PLG stage number used in the test printing before product shipment and the gap amount x applied to the current printing.

  In the next step S33, the inclination a is calculated. That is, the correction amount acquisition unit 64 calculates the inclination a by the expression a = (Y2-Y1) / (X2-X1) using the inclination calculation setting values (Y1, Y2, X1, X2).

In the next step S34, a correction amount difference dy is calculated. That is, the correction amount acquisition unit 64 calculates the difference dy by the following equation (2).
dy = int (dx · a + 0.5) (2)
Here, the operator int () represents the maximum integer that does not exceed the value in (), and in this example, the difference dy is obtained as an integer by rounding off the value of dx · a.

  In step S35, a correction amount ΔPF2 is calculated. That is, the correction amount acquisition unit 64 calculates the correction amount ΔPF2 by the equation ΔPF2 = Y1 + dy. When the correction amount ΔPF2 is thus calculated, the process proceeds to step S20 in FIG. Note that the interval acquisition unit 62 calculates the difference between the first gap amount Lpg corresponding to the number of PLG stages applied to printing and the thickness LP of the medium P, and calculates the second gap amount x (= Lpg−LP). ) And the correction amount ΔPF2 may be calculated using a calculation formula represented by a linear function of the gap amount x obtained by shifting the graph of FIG. 15 by the reference thickness LP0 in the minus X-axis direction.

  Next, the operation of the printing apparatus 11 of this embodiment will be described. As a premise, the conveyance amount is corrected when the printing method of the current printing is band printing. Band printing includes intermittent conveyance in which the medium P is greatly fed in the conveyance direction F at a conveyance distance near the nozzle row length of the print head 34.

  When the print command is received, the print color mode (monochrome / color), the print speed mode (high speed / low speed), the medium type and the medium size of the medium P to be printed are as follows. The determination is made based on print information or the like input from the PC 53. Then, the computer 50 refers to the PLG table data TD1 shown in FIG. 3 based on the medium type and the medium size, and acquires the number of PLG steps and the thickness LP of the medium P. Furthermore, the number of PLG stages is appropriately changed to an appropriate number of stages based on the distinction information between single-sided printing and double-sided printing and the information on whether the rubbing prevention function is valid / invalid. When the number of PLG stages is determined in this way, the control unit 60 drives the interval adjustment driving unit 59 as necessary to adjust to the selected number of PLG stages. As a result, the interval PLG between the print head 34 and the support base 35 is adjusted to the first gap amount Lpg corresponding to the number of PLG steps.

  Then, when the medium P is conveyed from the printing path K2 to the printing unit 14 by the conveying unit 13 and the leading edge of the conveyed medium P is detected by the medium sensor 55, for example, the number of pulse edges of the pulse from the encoder 54 is counted. Is started, the transport position of the medium P during printing is grasped based on the counted value. When the medium P reaches the printing start position, printing for one scan in which ink droplets are ejected from the print head 34 while the carriage 33 moves in the scanning direction S, and intermittent conveyance for conveying the medium P to the next printing position. Are alternately performed, the printing on the medium P is advanced. At the time of band printing including normal band printing and irregular band printing, the conveyance amount is corrected by a correction amount corresponding to the second gap amount x or the like prior to intermittent conveyance.

  Suppose now that the print setting conditions are the type of medium P is photographic paper, the medium size is 2L, the number of PLG stages is PLG4, the medium thickness LP is LP4 thicker than LP0, and printing is performed. It is assumed that the color mode is set to monochrome printing, the conveyance area is normal, and the printing speed mode (carriage speed) is set to high speed.

  Then, inclination calculation setting values (Y1, Y2, X1, X2) corresponding to the setting conditions are acquired with reference to the correction table data TD3 in the storage unit 52. That is, a gap amount Lpg (= 230 [0.01 mm]) corresponding to PLG4 is read out from the table data TD2 shown in FIG. 13, and at the same time, from the correction table data TD3 shown in FIG. In this case, setting values for slope calculation (Y1 = H3BK, Y2 = H5BK, X1 = 190, X2 = 255) are read out.

  Next, a second gap amount x that is the size of the interval PAG between the surface Pa of the medium P and the print head 34 at the time of the current printing is calculated. Assuming that the medium type of the medium P is glossy paper, the thickness LP of the glossy paper is thicker than the reference thickness LP0 (= 0.11 mm), so that the above-described equation (1) is used. The difference dx obtained in this way is calculated by dx = Lpg−X1− (Lp−Lp0). As shown in the graph of FIG. 15, when PLG4 and thickness LP4, the difference dx in the X-axis direction between the point of coordinates (X1, Y1) and point R is calculated as dx = 55−LP3. Further, using the equation (2), the correction amount difference dy is calculated by dy = int (dx · a + 0.5). Then, the correction amount ΔPF2 (= Y1 + dy) is calculated by adding the correction amount difference dy to the reference correction amount Y1. The transport amount PF of the medium P is corrected by using the correction amount ΔPF2 adapted to the number of PAG stages and the thickness LP of the medium P applied to this printing.

  Further, in the present embodiment, the ink ejection rate (%) (print duty) calculated based on the print data for one previous scan is used as a parameter, and this parameter is parallel to the transport direction F of the ink ejected from the print head 34. A contribution rate to the spread in a certain direction is obtained, and the correction amount ΔPF2 is adjusted according to the contribution rate. In addition, this parameter is set by the print head 34 using the average size of ink droplets calculated based on the print data for one previous scan or the average size of ink droplets obtained from print quality (standard / high definition) as a parameter. The degree of contribution is determined as to how much ink ejected from the ink is caused to flow in a direction parallel to the transport direction F due to the influence of wind. Then, the correction amount ΔPF2 is adjusted according to the contribution rate.

  For example, as shown in FIG. 7, when the carriage 33 moves in the scanning direction S, wind is generated by pushing away the air. In the process of moving the print head 34 while ejecting ink droplets from the nozzles 34N belonging to the adjacent nozzle rows, the print head 34 moves in the scanning direction S while forming a kind of curtain made of ink droplets. In the movement process of the print head 34, an air flow flows into the gap between the curtains of the ink droplets, so that the ink droplets spread outward in a direction parallel to the transport direction F (see FIGS. 7 and 8).

  At this time, the deviation amount of the ink droplet landing position in the transport direction is larger in FIG. 8 where the second interval PAG is relatively wide than in FIG. 7 where the second interval PAG is relatively narrow. . In this case, the correction amount ΔPF2 added to the carry amount in FIG. 8 is larger than the correction amount ΔPF2 added to the carry amount in the case of FIG. Further, the correction amount ΔPF2 is different depending on whether the print color is monochrome or color. This is because the density of black ink during monochrome printing differs from the density of color ink during color printing due to differences in pigments. As the ink density is larger, the correction amount is adjusted to be smaller because the ink is less likely to be blown by the wind.

  Further, in the process of printing one sheet of the medium P, the transport position of the medium P is supported by only the upstream transport roller pair 39 among the transport roller pairs 39 and 40 (FIG. 9) and the transport roller pair. A central region (FIG. 10) supported by both 39 and 40 and a lower end region (FIG. 11) supported only by the downstream conveying roller pair 39 are taken. Here, when the transport position of the medium P belongs to the lower end region, the already printed portion of the medium P is easily curled by swelling due to ink absorption, and the lower end portion is easily lifted from the support surface 35a. Yes. In this case, as shown in FIG. 12, when the lower end portion of the medium P is lifted obliquely at an angle θ, for example, it is smaller than the width L1 in the transport direction F of the ink landing range for the medium P indicated by a solid line that is not lifted. The width L2 of the ink landing range for the lifted medium P indicated by the dotted line becomes longer. However, in this embodiment, the correction amount of the conveyance amount when it is in the lower end region is made larger than the correction amount of the conveyance amount when it is in the normal region including the upper end region and the central region.

  For this reason, the relative positional deviation in the conveyance direction F between the printing result at the previous scanning and the printing result at the current scanning can be suppressed to be small. As a result, for example, the white banding area WA shown in FIG. 5 and the black banding area KA shown in FIG. 6 can be reduced or eliminated. Therefore, as shown in FIG. 4, high-quality band printing with suppressed banding can be performed.

According to the above embodiment, the following effects can be obtained.
(1) When printing is performed by ejecting ink from the print head 34 on the medium P transported to the printing unit 14 by the transport unit 13, the interval PAG between the surface Pa of the medium P and the print head 34 at the time of printing is set. The medium P is adjusted by the correction amount ΔPF2 corresponding to the size (second gap amount x). Therefore, for example, depending on the type of medium P to be printed, the medium P is transported by a transport amount suitable for the size of the interval PAG at the time of printing, so the position of the landing position of the ink INC generated in the transport direction F of the medium P Deviation can be suppressed.

  (2) When the moving speed of the print head 34 in the scanning direction S is relatively fast, the wind that the print head 34 pushes away the air during the movement is stronger than when the print head 34 moves slowly. When the positional deviation in the transport direction of the landing position of the ink INC increases, such positional deviation is suppressed. That is, the correction amount when the movement speed is the first movement speed is set to a value larger than the correction amount when the movement speed is the second movement speed that is slower than the first movement speed. When the same conveyance amount is commanded, the first adjusted conveyance amount at the first movement speed is adjusted to a value larger than the second adjustment conveyance amount at the second movement speed. Therefore, the medium P can be transported with an adjusted transport amount whose size is changed according to the difference in the moving speed of the print head 34, and also occurs in the transport direction of the medium P even when the moving speed of the print head 34 is different. The positional deviation of the landing position of the ink INC can be more appropriately suppressed.

  (3) When the transport amount PF is corrected by the correction amount ΔPF2 in order to reduce the deviation amount of the ink droplet landing position in the transport direction F due to the influence of wind, the size of the interval PAG between the print head 34 and the medium P The correction amount when the second value is larger than the first value is made larger than the correction amount when is the first value. Therefore, regardless of the size of the interval PAG between the print head 34 and the medium P, it is possible to appropriately reduce banding and provide a high-quality printed matter.

  (4) When the transport amount PF is corrected by the correction amount ΔPF2 in order to reduce the amount of deviation of the ink droplet landing position in the transport direction F due to the influence of wind, the carriage speed Vcr that is the moving speed of the print head 34 is the first speed. The correction amount when the carriage speed Vcr is at the second movement speed higher than the first speed is larger than the correction amount when the movement speed is at one. Therefore, regardless of the carriage speed Vcr, banding can be appropriately reduced and a high-quality printed matter can be provided.

  (5) When the carry amount PF is corrected by the correction amount ΔPF2 in order to reduce the deviation amount of the ink droplet landing position in the carry direction F due to the influence of wind, the correction amount when the print color mode is the monochrome print mode and The amount of correction when the print color was in color print mode was made different. Therefore, banding can be appropriately reduced regardless of whether the print color is monochrome or color, and a high-quality printed matter can be provided.

  (6) When the transport amount PF is corrected by the correction amount ΔPF2 in order to reduce the deviation amount of the ink droplet landing position in the transport direction F due to the influence of wind, the positional relationship between the medium P and the transport roller pair 39, 40 The correction amount when positioned in the lower end region is made larger than the correction amount when positioned in the normal region including the upper end region and the central region. Therefore, even if the medium P is located in any of the upper end region, the central region, and the lower end region, the banding can be appropriately reduced and a high-quality printed matter can be provided.

  (7) When the carry amount PF is corrected with the correction amount ΔPF2 in order to reduce the deviation amount of the ink droplet landing position in the carry direction F due to the influence of the wind, per pass in which the carriage 33 moves (scans) once. A different correction amount ΔPF2 corresponding to the ink discharge rate (print duty) (%) representing the ratio of the actual total discharge amount to the maximum total discharge amount that can be discharged by all the nozzles used was applied. In particular, the correction amount at the second rate, which is higher than the first rate, is made larger than the correction amount when the ink discharge rate (%) is the first rate. Therefore, both after finishing printing for one line in a pass with a high ink discharge rate (%) and after finishing printing for one line with a pass with a low ink discharge rate, each ink discharge rate (%). Accordingly, the medium P can be transported with an appropriate transport amount after correction according to the degree of spreading of the ink droplet landing position in the transport direction F. Therefore, it is possible to appropriately reduce banding and provide a high-quality printed matter.

  (8) When the transport amount PF is corrected by the correction amount ΔPF2 in order to reduce the shift amount of the ink droplet landing position in the transport direction F due to the influence of wind, the average size of the ink droplets is the first average size. The correction amount when the second average size is smaller than the first average size is made larger than the correction amount at that time. Therefore, both the first average size of the ink droplets having a relatively large average size and the second average size having a relatively small average size both appropriately reduce banding and provide a high-quality printed matter. Can do.

  (9) When the transport amount PF is corrected by the correction amount ΔPF2 in order to reduce the deviation amount of the ink droplet landing position in the transport direction F due to the influence of the wind, the weight (μg) of the ink droplet is the first weight. The correction amount when the second weight is smaller than the first weight is made larger than the correction amount at a certain time. Therefore, regardless of the weight of the ink droplet, banding can be appropriately reduced and a high-quality printed matter can be provided.

  (10) When the carry amount PF is corrected by the correction amount ΔPF2 in order to reduce the deviation amount of the ink droplet landing position in the carry direction F due to the influence of the wind, the ink density (g / ml) is the first density. The correction amount when the second density is smaller than the first density is made larger than the correction amount when. Therefore, regardless of the density of the ink, banding can be appropriately reduced and a high-quality printed matter can be provided.

  (11) Normal band printing method and irregular band printing method, etc. include intermittent conveyance in which the medium P is greatly fed by a predetermined distance equal to the entire nozzle pitch length or a predetermined distance shorter than the entire nozzle pitch length and close to the entire nozzle pitch length. When band printing is performed, the carry amount is corrected by the correction amount ΔPF2. Therefore, it is possible to suppress a relative positional shift in the transport direction F between the printing result before the medium P is largely fed and the printing result after the medium P is largely fed in the band printing method. As a result, it is possible to reduce banding caused by overlapping or gaps between the print results (print dot groups) before and after the medium P is largely fed. In this respect, it is possible to avoid a decrease in the quality of the printed image.

  (12) A second gap amount x (= Lpg−LP) which is the size of the distance PAG between the print head 34 and the surface P of the medium P based on the medium information included in the print information input together with the image information. ) Is determined. That is, referring to the PLG table data TD1 (FIG. 3) based on the medium type and medium size included in the medium information, the PLG stage number and the thickness LP of the medium P are obtained, and the first gap corresponding to the PLG stage number is obtained. The second gap amount x is obtained by subtracting the thickness LP from the amount Lpg (FIG. 13). The correction amount ΔPF2 can be easily obtained based on the second gap amount x determined in this way.

  (13) The first gap amount Lpg corresponding to the distance between the support base 35 and the print head 34 at the time of printing is acquired, and the reference first gap amount Lpg stored in the storage unit 52 in advance and the correction amount Correction table data TD3 including a plurality of sets of combinations is stored in the storage unit 52. Two sets of data including two first gap amounts sandwiching the value of one first gap amount Lpg acquired with reference to the PLG table data TD1 based on the medium information are acquired from the correction table data TD3. Then, an interpolation calculation is performed using the two sets of acquired set data to acquire a correction amount for one first gap amount Lpg. In other words, the adjustment amount dy is obtained based on the equation (2) using the difference dx obtained from the equation (1), and the correction amount (Y1 + dy) is obtained by adding the adjustment correction amount dy to the reference correction amount Y1. The first gap amount at the time of printing using the first gap amount Lpg based on the medium information and the two sets of data composed of the two reference first gap amounts Lpg and the correction amount as described above. A correction amount according to Lpg and the thickness LP of the medium P can be acquired relatively easily. Therefore, the correction amount corresponding to the number of PLG stages (first gap amount Lpg) other than the reference set data is set to the second gap amount x while keeping the number of reference set data stored in the storage unit 52 small. Can be obtained relatively easily without directly calculating.

In addition, you may change the said embodiment as shown below.
Although the calculation formula is a linear function, a calculation formula represented by a curve function such as a quadratic function or a cubic function in which the rate of increase in the correction amount gradually increases as the medium surface gap increases may be used. For example, as shown in FIG. 18, the curve functions f1 (x) to f4 (x) are used in the high-speed printing mode, and the curve functions g1 (x) to g4 (x) are used in the low-speed printing mode. According to this configuration, since the function of the calculation formula is not an approximate expression, the correction amount ΔPF2 with higher accuracy can be acquired, and the transport amount can be corrected more appropriately. As a result, banding can be more effectively reduced.

  In place of the configuration using the calculation formula indicating the relationship between the gap amount and the correction amount, a correction table (an example of reference data) including all combinations of the gap amount and the correction amount may be stored in the storage unit 52. In this case, the corresponding correction amount ΔPF2 is acquired by referring to the correction table based on the gap amount applied during the current printing. For example, in obtaining the correction amount for correcting the carry amount, it is possible to omit a calculation process using a calculation formula.

-Printing color (monochrome printing / color printing) may not be used as a parameter for determining the correction amount.
The correction amount may be increased when the transport position of the medium P belongs to the upper end area during printing as compared to when it belongs to the center area. Further, the configuration may be such that whether the transport area to which the transport position of the medium P belongs is the normal area or the lower end area is not a parameter for determining the correction amount.

  ・ When determining the number of PLG steps (or gap amount Lpg) to be applied at the time of printing, all of medium information (medium type, medium size), single-sided printing or double-sided printing discrimination information, and anti-friction function valid / invalid information It does not have to be based on information, but may be based on at least one piece of information. For example, the rubbing prevention function may be eliminated. For example, the same number of PLG steps (gap amount Lpg) may be set for single-sided printing and double-sided printing.

  The correction of the transport amount is not limited to correction that increases the transport amount by adding the correction amount due to the influence of the wind to the transport amount before correction, for example, the transport amount by subtracting the correction amount from the transport amount before correction It is good also as correction which makes small. For example, when the ink landing area is relatively narrow with respect to the used nozzle area in the transport direction F due to the influence of wind, the correction amount is subtracted from the transport amount before correction (or a negative correction amount is added). Thus, banding can be reduced.

  The second gap amount x, which is the size of the interval PAG between the print head 34 and the medium P, is obtained by subtracting the thickness LP of the medium P from the first gap amount Lpg. A gap amount x of 2 may be acquired. For example, table data in which the medium information (medium type and medium size) and the second gap amount x are associated is stored in the storage unit 52, and the table data is referred to from the medium information and the second data corresponding to the medium information is stored. A gap amount x of 2 may be acquired. Further, the second gap amount x may be acquired based on information other than the medium information commission in the print information. Further, the second gap amount x (paper gap) may be acquired by detecting the distance between the print head and the surface of the medium with a distance sensor.

The PAG may be obtained without adjusting the PLG even when the moving speed of the print head 34 in the scanning direction S is different from the threshold speed.
In the above embodiment, the liquid ejecting apparatus is not limited to the printing apparatus 11 that ejects ink, and may be a liquid ejecting apparatus that ejects liquid other than ink. In this type of liquid ejecting apparatus as well, the positional deviation of the ejected liquid (droplet) landing position on the medium in the transport direction can be reduced, and the landing position accuracy of the liquid droplet can be increased.

  The correction of the conveyance amount by the correction amount ΔPF2 due to the influence of the wind may be applied to only one of the normal band printing and the irregular band printing belonging to the band printing. In addition to normal band printing and irregular band printing, the conveyance amount may be corrected in a printing method in which large feed (for example, a conveyance distance of 2/3 or more of the nozzle row) is performed.

  -The application of the carry amount correction is not limited to printing methods including large feed. For example, the correction by the correction amount ΔPF2 of the transport amount is applied to a printing method in which the medium P is transported by a small feed by a predetermined pitch such as 1/2, 1/3, or 1/4 of the length of the used nozzle in the transport direction. May be. According to this configuration, it is possible to suppress a shift in the transport direction F between the previous print result and the current print result before and after the small-feed transport of the medium P.

  As the parameter for determining the correction amount, an appropriate parameter that causes a shift in the transport direction due to the influence of the wind at the landing position of the ink droplet can be selected. For example, only the number of PLG stages (or the first gap amount Lpg) or only the second gap amount x may be used as a parameter. For example, the transport amount may be corrected with a correction amount corresponding to the first gap amount Lpg. Thus, since the thickness LP of the medium P with respect to the first gap amount Lpg is considerably small, the first gap amount Lpg is taken as an example of the interval size without considering the thickness LP of the medium P. Even if it is a structure, the fall of the printing quality resulting from the position shift of the landing position of the ink which arises in the conveyance direction F of a medium can be suppressed.

  The parameter for determining the correction amount may be only information related to the moving speed of the print head 34 (or the carriage speed Vcr) at the time of printing, or the print head moving speed such as the print speed mode (high speed / low speed). Furthermore, only the ink discharge rate (%) (print duty) may be used as a parameter, or only the print color may be used as a parameter. Alternatively, only the average size of ink droplets per scan of the print head 34 may be used as a parameter, or only the average weight or average density of ink droplets may be used as a parameter. Further, the correction amount may be determined by combining a plurality of types of parameters such as two or three of the above-described plurality of parameters.

  -It may replace with the space | interval adjustment drive part 59, and the structure provided with the space | interval adjustment mechanism which can adjust PLG stage number (or 1st gap amount Lpg) by manual operation, for example may be sufficient. In this case, the interval may be detected by a sensor, or the user may input the interval to the printing apparatus 11 by operating the operation unit 18.

  The present invention may be applied to a printing apparatus in which only one fixed first gap amount Lpg or second gap amount x is used. That is, the gap amount Lpg, x need not be a parameter that determines the correction amount. In this case, the correction amount may be changed according to the carriage speed. That is, when the moving speed of the print head 34 (that is, the carriage speed Vcr) based on the mode information regarding the printing speed included in the printing information acquired by the data acquiring unit 61 (an example of the speed information acquiring unit) is the first moving speed. Instead, the correction amount is increased at a second movement speed that is slower than the first movement speed. Even with this configuration, even if the landing position of the ink droplets shifts in the transport direction due to the influence of the wind, the positional shift of the relative position in the transport direction between the previous print result and the current print result is suppressed, and the print quality is reduced. Can be suppressed.

The technical idea grasped from the embodiment and the modified examples will be described below.
(1) A conveyance unit that conveys a medium, a printing unit that performs printing by ejecting liquid from the print head onto the medium while moving in a direction that intersects the conveyance direction of the medium, and when the print head performs printing A speed information acquisition unit that acquires information on the moving speed of the medium, and an adjustment transport amount is acquired by correcting the transport amount of the medium by a correction amount corresponding to the movement speed acquired by the speed information acquisition unit, and the transport unit And a controller that controls the medium to convey the medium by the adjusted conveyance amount. According to this configuration, in the process until the liquid ejected from the print head lands on the medium due to the airflow generated by pushing away air in the printing apparatus when the print head moves in the direction intersecting the transport direction. Even if the landing position is deviated in the carrying direction due to the flow, the medium is carried by the adjusted carry amount in which the carry amount is corrected by the correction amount corresponding to the deviation amount. Therefore, the next printing can be performed at an appropriate position with respect to the printing result before the medium is conveyed.

  DESCRIPTION OF SYMBOLS 11 ... Printing apparatus as an example of a liquid discharge apparatus, 13 ... Conveyance part, 14 ... Printing part, 34 ... Print head, 34N ... Nozzle, 45 ... Controller, 50 ... Computer, 52 ... Memory | storage part, 60 ... Control part, 61 ... Data acquisition unit, 62 ... Interval acquisition unit constituting an example of correction unit, 63 ... Judgment unit constituting an example of correction unit, 64 ... Correction amount acquisition unit constituting an example of correction unit, P ... Media, Pa ... Front surface, TD1... PLG table data as an example of reference data and first reference data, TD2... Table data, TD3 as an example of second reference data, dx... Difference, dy. PF ... conveyance amount, LP ... medium thickness, PLG ... interval (first interval), Lpg ... first gap amount, PAG ... interval (second interval), x ... second gap amount, [Delta] PF ... correction amount.

Claims (11)

A transport unit for transporting the medium;
A printing unit that performs printing by discharging liquid from a print head to the medium while moving in a direction that intersects the conveyance direction of the medium;
A correction unit that corrects the conveyance amount of the medium by a correction amount according to the size of the interval between the surface of the medium and the print head in the printing unit;
And a control unit configured to control the transport unit to transport the medium by the corrected transport amount. The correction unit is
An interval obtaining unit for obtaining a size of an interval between the surface of the medium and the print head in the printing unit;
The printing apparatus according to claim 1, further comprising: a correction amount acquisition unit that corrects the conveyance amount of the medium by a correction amount corresponding to the size of the interval. A storage unit for storing reference data in which a first gap amount, which is a size of a gap between the support unit supporting the medium and the print head, and a thickness of the medium are individually associated with each other for each medium information; Prepared,
The interval acquisition unit acquires medium information, acquires the first gap amount and the thickness of the medium corresponding to the medium information with reference to the reference data based on the medium information, 3. The printing apparatus according to claim 2, wherein a second gap amount that is a size of the gap between the surface of the medium and the print head is obtained by subtracting the thickness of the medium from the gap amount. . First reference data in which a first gap amount, which is a size of a gap between a support unit capable of supporting the medium and the print head, is individually associated for each of a plurality of types of medium information, and the first A storage unit that stores second reference data including a plurality of sets of set data in which the gap amount and the correction amount are individually associated,
The correcting unit refers to the first reference data based on the acquired medium information, acquires one first gap amount according to the medium information, and sets the value of the first first gap amount. Two sets of data including two other first gap amounts having two sandwiched values and correction amounts corresponding to the other two first gap amounts are acquired from the second reference data, and The printing apparatus according to claim 1, wherein the correction amount corresponding to the one first gap amount is obtained by performing an interpolation calculation using two sets of data.   5. The printing according to claim 1, wherein the correction unit corrects the transport amount by the correction amount when the control unit performs printing corresponding to band printing. 6. apparatus.   The correction unit makes the correction amount larger when the movement speed of the print head is the first movement speed than when the movement speed is the second movement speed slower than the first movement speed. The printing apparatus according to claim 1, wherein:   The correction unit is configured to increase a correction amount when the interval is a second value having a wider interval than the first value, compared to a correction amount when the interval is a first value. The printing apparatus as described in any one of Claims 1-6. The print head can eject droplets of different weights,
The correction unit increases a correction amount when discharging a droplet having a second weight that is lighter than the first weight, than a correction amount when discharging a droplet having the first weight. The printing apparatus according to claim 1, wherein the printing apparatus is a printer. Monochrome print mode and color print mode are provided as print modes.
The printing apparatus according to claim 1, wherein the correction unit changes the correction amount between the monochrome printing mode and the color printing mode.   The correction unit is more than the correction amount when the liquid discharge rate ratio representing the ratio of the actual total discharge amount to the maximum total discharge amount that can be discharged by one movement of the print head is the first rate. 10. The printing apparatus according to claim 1, wherein the correction amount when the second rate is higher than the rate of 1 is made larger. 11. A transport unit that transports the medium in the transport direction, a printing unit that performs printing by discharging liquid from the print head onto the medium while moving in a direction intersecting the transport direction, and the transport unit and the printing unit are controlled. A printing control program to be executed by a computer in a printing apparatus including a control unit,
On the computer,
A correction step of acquiring a size of an interval between the surface of the medium and the print head in the printing unit, and correcting a conveyance amount of the medium by a correction amount according to the size of the interval;
And a control step of transporting the medium by the transport amount after correction by controlling the transport unit.