JP6602082B2 - Inkjet printing method and inkjet printing apparatus - Google Patents

Description

  The present invention relates to an ink jet printing method and an ink jet printing apparatus that print an image by ejecting ink (ink droplets) onto a transported print medium, and more particularly, to a labyrinth technique for preventing clogging.

  The ink jet printing apparatus includes a transport mechanism that transports continuous paper (print medium) and a print (printing) head that discharges ink onto the transported continuous paper. In order to prevent clogging, the inkjet printing apparatus periodically performs a lasing that ejects ink from all nozzles of the print head at the position of the ink receiving member (see, for example, Patent Document 1). Further, the lasing is performed in a non-printing area of continuous paper that is not used as a printing area for image data, such as between printing areas for image data exemplified by characters, graphics, and photographs.

JP 2005-262551 A

  However, the conventional example having such a configuration has the following problems. In other words, the ink jet printing apparatus performs the lainishing on the conveyed continuous paper, but there is a problem in that the ink drying property is poor, such as the ink adhering to the continuous paper bleeding. As a result, problems such as transfer to another part of the adhered ink and show-through occur. Therefore, it is desired to improve the drying property of the ink adhered by the lainishing.

  In addition, as shown in FIG. 8A, the laundering is performed at the page head position TP which is a non-printing area, while the print start mark MA1 is also printed at the page head position TP. For this reason, an overlapping area K1 that overlaps between the print start mark MA1 and the laminating areas C, M, and Y occurs. For this reason, the total ink discharge amount (total ink adhesion amount) per unit area of the overlapping region K1 increases, and there arises a problem that the drying property of the ink is further deteriorated.

  The reason why the overlapping area K1 occurs will be specifically described. The print start mark MA1 is a mark for determining the print start timing for back side printing, and is preferably printed at the page top position TP. On the other hand, the lainishing is performed across the width direction 202 of the continuous paper WP by ejecting ink from all nozzles of the print head (see FIG. 8B). For this reason, the lainishing cannot be performed except for the print start mark MA1. Further, if the printing start mark MA1 and printing are performed in an area shifted in the conveyance direction 201 of the continuous paper WP, the non-printing area becomes large. For example, the continuous paper WP is unnecessarily consumed and the image data printing area Will decrease.

  This invention is made | formed in view of such a situation, Comprising: It aims at providing the inkjet printing method and inkjet printing apparatus which can improve the drying property of the adhering ink.

In order to achieve such an object, the present invention has the following configuration.
That is, the ink jet printing method according to the present invention is an ink jet printing method for printing an image by ejecting ink onto a transported print medium, and a plurality of ink jet nozzles for ejecting ink intersect with the transport direction of the print medium. A control unit that controls the print heads arranged in the width direction executes a lainwashing process that causes lainishing to eject ink from the inkjet nozzles related to all image printing on the transported print medium. The lainwashing step includes (a) ejecting ink at least once to the transported print medium in any one of two or more groups obtained by grouping the plurality of inkjet nozzles; ) The step (a) is performed, and the transported print medium is preliminarily performed. Case of discharging a constant and number of times ink, a step of alternating the other of said groups, and a step of causing at least one round ejection of ink by each group of (c) the step (a) and the step (b) The control unit further includes a mark printing step for printing a page information mark indicating information on a page of the print medium on the transported print medium, which is performed together with the lainishing, The page information mark is set so that there is an overlapping area in which an area where the page information mark is printed with a set color ink and an area where the lainwashing is performed with an ink of a color other than the color overlap. The mark printing step for printing is performed .

According to the ink jet printing method of the present invention, the control unit causes the printing medium to perform the lasing that ejects ink from the ink jet nozzles related to all image printing. In that case, a control part discharges an ink at least once with respect to the conveyed printing medium in either of two or more groups which divided the some inkjet nozzle into groups. At the same time, when the ink is ejected a predetermined number of times on the transported print medium, the control unit switches to another group. Then, the controller causes at least one round of ink ejection by each group. As a result, the amount of ink adhering per unit area due to the lainishing can be reduced, and the drying property of the ink can be improved.
Also, for example, it is assumed that there is an overlapping area where a printing area of a page information mark printed with black ink overlaps with an area where lainishing is performed with cyan ink other than black. Even in this case, the amount of ink adhering per unit area due to lainishing is small, so that it is possible to improve the drying property of the ink in the overlapping region. In addition, by overlapping the page information mark print area and the area where the lainishing is performed, the print area of the image data can be increased in the transport direction of the print medium.

  Moreover, in the ink jet printing method according to the present invention, it is preferable that the ink jet nozzles of each group are arranged in every other one or plural. Thereby, it is possible to suppress unevenness in the drying property of the ink.

  In the inkjet printing method according to the present invention, the mark printing step may include (d) adhering ink per unit area for printing the page information mark in the overlapping region when printing the page information mark. It is preferable that the method includes a step of reducing the amount as compared with a region where the page information mark is printed other than the overlapping region and the region where the lainishing is performed. This makes it possible to reduce the ink adhesion amount per unit area of the page information mark while supplementing the density necessary for mark detection in the overlapping region. Therefore, in the overlapping area, it is possible to reduce the ink adhesion amount per unit area for both printing of the page information mark and the lainishing, and further, it is possible to improve the drying property of the ink in the overlapping area.

The ink jet printing apparatus according to the present invention is an ink jet printing apparatus that prints an image by ejecting ink onto a transported print medium, and a plurality of ink jet nozzles that eject ink intersect the transport direction of the print medium. A print head arranged in a width direction; and a control unit that controls the print head, wherein the control unit performs ink from the inkjet nozzles related to all image printing on the transported print medium. The labyrinth is discharged, and the control unit performs at least the print medium to be conveyed in any of two or more groups obtained by grouping the plurality of inkjet nozzles when performing the lainwashing. Ink is ejected once and the ink is ejected a preset number of times for the transported print medium. Is alternation to other of said groups when issued, the ejection of the ink by each group is at least one round, the control unit may further together with the line flushing, the printing medium is the transport, which is set in advance The page information of the print medium is changed so that there is an overlapping area in which the area where the page information mark is printed with the color ink and the area where the lainwashing is performed with the ink of a color other than the color. The page information mark shown is printed .

According to the ink jet printing apparatus of the present invention, the control unit causes the laminating to eject ink from the ink jet nozzles related to all image printing on the print medium. In that case, a control part discharges an ink at least once with respect to the conveyed printing medium in either of two or more groups which divided the some inkjet nozzle into groups. At the same time, when the ink is ejected a predetermined number of times on the transported print medium, the control unit switches to another group. Then, the controller causes at least one round of ink ejection by each group. As a result, the amount of ink adhering per unit area due to the lainishing can be reduced, and the drying property of the ink can be improved.
Also, for example, it is assumed that there is an overlapping area where a printing area of a page information mark printed with black ink overlaps with an area where lainishing is performed with cyan ink other than black. Even in this case, the amount of ink adhering per unit area due to lainishing is small, so that it is possible to improve the drying property of the ink in the overlapping region. In addition, by overlapping the page information mark print area and the area where the lainishing is performed, the print area of the image data can be increased in the transport direction of the print medium.

  According to the ink jet printing method and the ink jet printing apparatus according to the present invention, the control unit causes the printing medium to perform the lasing that ejects ink from the ink jet nozzles related to all image printing. In that case, a control part discharges an ink at least once with respect to the conveyed printing medium in either of two or more groups which divided the some inkjet nozzle into groups. At the same time, when the ink is ejected a predetermined number of times on the transported print medium, the control unit switches to another group. Then, the controller causes at least one round of ink ejection by each group. As a result, the amount of ink adhering per unit area due to the lainishing can be reduced, and the drying property of the ink can be improved.

It is a figure which shows schematic structure of the inkjet printing apparatus which concerns on an Example. (A), (b) is a figure for demonstrating the structure of a print head. (A) is a figure which shows the example of the discharge of the conventional lain ashing, (b) is a figure which shows the example of the discharge of the lain ashing which concerns on this invention. (A)-(c) is a figure which shows the other example of discharge of the lainishing which concerns on this invention. (A), (b) is a figure which shows the other example of discharge of the lainishing which concerns on this invention. (A)-(c) is a figure for demonstrating the operation | movement of printing of a printing start mark, and a labyrinth operation. It is a figure which shows the printing area | region of the cutter mark which concerns on a modification, a lainishing area | region, etc. FIG. (A) is a figure which shows the printing area | region of a printing start mark, and a lainishing area | region, (b) is a figure which mainly shows a laminating area | region.

  Embodiment 1 of the present invention will be described below with reference to the drawings. FIG. 1 is a diagram illustrating a schematic configuration of the ink jet printing apparatus according to the first embodiment. 2A and 2B are diagrams for explaining the configuration of the print head.

  Please refer to FIG. The ink jet printing apparatus (hereinafter referred to as “printing apparatus”) 1 includes a paper feeding unit 3, a front surface printing unit 5, a reversing unit 7, a back surface printing unit 9, and a paper discharge unit 11.

  The paper supply unit 3 holds the roll-shaped continuous paper WP so as to be rotatable about a horizontal axis, and unwinds and supplies the continuous paper WP to the front surface printing unit 5. The front surface printing unit 5 is, for example, an ink jet type, and performs printing on the surface of the continuous paper WP. The reversing unit 7 includes a plurality of rollers and reverses the surface of the continuous paper WP downward. The back surface printing unit 9 is, for example, an ink jet type, and performs printing on the back surface of the continuous paper WP. The paper discharge unit 11 winds the continuous paper WP that has been printed on the front and back surfaces in a roll shape around the horizontal axis.

  If the supply side of the continuous paper WP is the upstream side and the discharge side of the continuous paper WP is the downstream side, the paper feed unit 3 is disposed upstream of the front surface printing unit 5, and the paper discharge unit 11 is the back surface printing unit 9. It is arranged downstream. The continuous paper WP corresponds to the printing medium of the present invention.

  The front surface printing unit 5 includes a driving roller 13 for taking in the continuous paper WP from the paper feeding unit 3 on the upstream side. The continuous paper WP unwound from the paper feeding unit 3 by the driving roller 13 is conveyed downstream along the plurality of conveying rollers 15. The front surface printing unit 5 includes a driving roller 17 on the most downstream side. Between the driving roller 13 and the driving roller 17, a printing unit 19 and a drying unit 21 are arranged in that order from the upstream side. The printing unit 19 includes a print head 23 that ejects ink (ink droplets). The drying unit 21 dries the portion printed by the printing unit 19.

  The reversing unit 7 reverses the front and back of the continuous paper WP sent out from the driving roller 17 of the front surface printing unit 5. Further, the reversed continuous paper WP is sent out toward the back surface printing unit 9.

  The back surface printing unit 9 includes a driving roller 25 for taking in the continuous paper WP from the reversing unit 7 on the upstream side. The continuous paper WP taken in by the driving roller 25 is conveyed downstream along a plurality of conveying rollers 27. The back surface printing unit 9 includes a driving roller 29 on the most downstream side. An imaging unit 30, a printing unit 31, a drying unit 33, and a double-sided inspection device 35 are arranged in this order from the upstream side between the driving roller 25 and the driving roller 29. The printing unit 31 includes a print head 37 that ejects ink. The drying unit 33 dries the portion printed by the printing unit 31. The double-sided inspection device 35 inspects both sides of the continuous paper WP printed by the printing units 19 and 31.

  The transport rollers 15 and 27 are rotatable rollers that do not have a drive mechanism. The drive rollers 13, 17, 25, and 29 are rotated by a drive unit such as a motor.

  The photographing unit 30 is arranged to be spaced downward on the lower surface side of the continuous paper WP. The imaging unit 30 captures an area including the print start mark MA1 printed on one part of the continuous paper WP as an optical image. The print start mark MA1 is a mark for determining the print start timing for back side printing. Printing of the print start mark MA1 and line infrasing are performed by the front surface printing unit 5. Based on the image of the area including the print start mark MA1 photographed by the photographing unit 30, the mark detection unit 39 detects the print start mark MA1. Further, the mark detection unit 39 outputs a signal indicating the print start mark MA1 to the control unit 43 which will be described later, and back side printing is performed.

  Here, the printing unit 19 of the front surface printing unit 5 will be described. The printing unit 19 includes a plurality of (for example, four) print heads 23 arranged along the conveyance direction 201 of the continuous paper WP. Each print head 23 is a first print head 23a, a second print head 23b, a third print head 23c, and a fourth print head 23d in order from the upstream side. The continuous paper WP is printed in this order. Each of the print heads 23a to 23d is arranged apart from each other by a predetermined distance in the transport direction 201. The print head 23 is driven by a piezo method or a thermal method to discharge ink.

  Four print heads 23a to 23d eject ink and print. For example, the first print head 23a ejects black (K) ink, and the second print head 23b ejects cyan (C) ink. The third print head 23c ejects magenta (M) ink, and the fourth print head 23d ejects yellow (Y) ink. Each color ink is supplied from a supply unit (not shown).

  As shown in FIG. 2A, the print head 23 includes a plurality of inkjet nozzles 41 that eject ink. The plurality of inkjet nozzles 41 are arranged (arranged) over the width direction 202 of the continuous paper WP with a length equal to or longer than the width of the continuous paper WP. The width direction (main scanning direction) 202 of the continuous paper WP is substantially orthogonal to (intersects) the conveyance direction (sub-scanning direction) 201 of the continuous paper WP. In FIG. 2 (a), the inkjet nozzles 41 are arranged in a line, but may be configured in a staggered arrangement as shown in FIG. 2 (b). In FIG. 2A and FIG. 2B, the print head 23 is configured as a single unit, but printing is performed by arranging a plurality of short inkjet heads in a row or a staggered pattern in the width direction 202. The head 23 may be configured. The print head 23 is fixed with respect to the conveyance direction 201 and the width direction 202 at the installation position.

  In addition, although the printing part 31 of the back surface printing unit 9 is provided with the print head 37 (37a-37d), since it is comprised similarly to the above-mentioned printing part 19, the description is abbreviate | omitted. Further, when the print heads 23a to 23d are not particularly distinguished, the print heads 23 will be described. This also applies to the print head 37 and the like.

  In addition, the printing apparatus 1 includes a control unit 43 and a setting unit 45 as shown in FIG. The control unit 43 controls each component of the printing apparatus 1 such as the front surface printing unit 5 and the back surface printing unit 9 in an integrated manner. The control unit 43 is configured by a computer, for example, and includes a liquid crystal monitor that displays an operation screen and the like, a setting unit 45 that functions as an input unit such as a keyboard and various switches, a storage unit that stores image data and the like, And an arithmetic processing unit (CPU). Note that the storage unit stores a print start mark MA1 and a discharge waveform signal for normal printing for printing image data, and a discharge waveform signal for lainwashing for lainishing.

  Next, the control unit 43 that is a characteristic part of the present invention will be further described. The control unit 43 controls (instructs) the ink ejection operation by the print head 23. Then, as described below, the control unit 43 performs the lasing that ejects ink from all the inkjet nozzles 41. Each inkjet nozzle 41 ejects a preset number of inks, and all the inkjet nozzles 41 eject the same number (the same total amount) of ink.

  Further, the lay infiltration is performed by a discharge waveform signal for the lay infiltration. A single ink discharge amount based on the discharge waveform signal for lainishing is set to be larger than a single ink discharge amount based on the discharge waveform signal for normal printing.

  FIG. 3A is a view showing an example of discharge of conventional lay infrassing. The positions of the dots generated as a result of ejecting the ink are densely arranged so as to be solid. On the other hand, FIG. 3B is a diagram showing a discharge example of the labyrinth according to the present invention. The positions of dots generated as a result of ejecting ink are arranged in a checkered pattern. In other words, the control unit 43 ejects ink in a checkered pattern in the lay infrasing.

  The labyrinth operation by the control unit 43 will be specifically described. The control unit 43 divides the plurality of ink jet nozzles 41 into two first groups GR1 and second groups GR2 when performing the labyrinth (see FIG. 2A and the like). That is, the control unit 43 divides the dot rows arranged in one row in FIG. 3A into the first group GR1 and the second group GR2, as shown in FIG. 3B. This grouping is set in advance.

  In addition, the control unit 43 performs ink at least once (a preset number of times) with respect to the continuous paper WP conveyed in one of the two first groups GR1 and GR2, for example, the first group GR1. To discharge. At the same time, when the control unit 43 ejects ink for a preset number of times (for example, once) on the conveyed continuous paper WP, the control unit 43 switches to another second group GR2. Then, the control unit 43 causes at least one round of ink ejection by the groups GR1 and GR2.

  In FIG. 3 (b), ink is ejected once to the other continuous group WP to be transferred to the other second group GR2, and ink is ejected once to be changed to the other first group GR1. ing. Then, the ink ejection by each group GR1, GR2 is performed twice. The rotation of the first group GR1 and the second group GR2 may be two or more rounds. The number of circulations is set by a preset number of times of discharge of lain ashing.

  Note that the control unit 43 continuously discharges ink at a predetermined timing to the continuous paper WP being conveyed. In FIG. 3A, all the inkjet nozzles 41 are discharged twice continuously at a predetermined timing. In FIG. 3B, ink is ejected once at a predetermined timing in the first group GR1, and ink is ejected once at a predetermined timing in the second group GR2. The predetermined timing indicates the timing for forming the next adjacent dot when dots are continuously formed in the transport direction 201.

  In addition, the ink jet nozzles 41 (see FIG. 2A, etc.) of each group GR1, GR2 are arranged in either one (dot) or plural arrangement. By arranging the positions of the dots generated as a result of ejecting the ink so as to be equally spaced, it is possible to suppress the occurrence of unevenness in the drying property of the ink. In FIG. 3B, the positions of dots generated as a result of ejecting ink are arranged every other dot. It is preferable that the preset number for changing the group is not a variable number but a constant number. Also in this case, the positions of the dots are equally spaced, and unevenness in the drying property of the ink can be suppressed.

  Moreover, you may make the control part 43 control as FIG. 4 (a)-FIG.4 (c), FIG.5 (a), and FIG.5 (b).

  In FIG. 4A, the positions of dots generated as a result of ejecting ink are adjacent to each other. A plurality (for example, two) of the inkjet nozzles 41 (see FIG. 2A, etc.) of each group GR1, GR2 are adjacent to each other. A plurality of (for example, two) adjacent inkjet nozzles 41 are arranged at intervals of a plurality (for example, two) in the width direction 202.

  In FIG. 4B, when the ink is ejected a preset number of times (for example, twice) for the conveyed continuous paper WP, the control unit 43 changes to the other second group GR2, for example. In this example, every time ink is ejected, the other group is not changed, but before the group is changed, the ink is continuously ejected twice in the same group.

  In FIG. 4C, the methods of FIG. 4A and FIG. 4B are combined. That is, a plurality of (for example, two) dot positions formed as a result of ink ejection are adjacent to each other, and ejected twice in the transport direction 201 to change the group.

  In FIG. 5A, the plurality of inkjet nozzles 41 (see FIG. 2A and the like) are divided into three groups GR1, GR2, and G3. When the controller 43 ejects ink for a preset number of times (for example, once) on the conveyed continuous paper WP, the control unit 43 switches to another group GR2, for example. Then, the control unit 43 causes ink ejection by the groups GR1, GR2, and G3 to go through two cycles in the order of the first group GR1, the second group GR2, and the third group G3. In FIG. 5A, the positions of the dots are not checkered but diagonal.

  FIG. 5B shows a state where the positions of the dots of the groups GR1 and GR2 are not arranged at equal intervals between the ranges R. That is, the inkjet nozzles 41 (see FIG. 2 (a)) of each group GR1, GR2 do not have to be arranged either every other or every plurality.

  Next, the operation of the printing apparatus 1 will be described.

  The print start mark MA1 is a mark used in double-sided printing, and is a mark printed on the surface of the continuous paper WP by the print head 23 of the surface printing unit 5 in FIG. As shown in FIG. 2A, the print start mark MA1 is arranged on the downstream side of the continuous paper WP from the page head position TP, and is arranged at the left end in the width direction 202 of the continuous paper WP. After printing the print start mark MA1, in the back surface detection unit 9, the photographing unit 30 photographs an image including the print start mark MA1, and the mark detection unit 39 detects the print start mark MA1 based on the photographed image. Thereby, the printing timing of the back surface can be determined by the print head 37, and the positions of the front and back pages can be aligned.

  First, an outline of the operation by the control unit 43 in FIGS. 6A to 6C will be described. The control unit 43 performs the lainwashing on the continuous paper WP (corresponding to the lainwashing process of the present invention) and prints the print start mark MA1 together with this lainwashing (corresponding to the mark printing process of the present invention). ). Further, in any one of the lasing and the printing start mark MA1, the control unit 43 uses the printing start mark MA1 printed with black ink and inks of colors other than the color (that is, cyan, magenta, yellow). It is determined whether or not there is an overlapping area K1 in which the areas C, M, and Y in which the labyrinth is performed overlap.

  As shown in FIG. 2A and FIG. 3B, the control unit 43 divides the plurality of inkjet nozzles 41 into two first groups GR1 and second groups GR2 in advance. The control unit 43 performs continuous paper transported in one of the two first groups GR1 and GR2, for example, the first group GR1, when performing lainwashing with black, cyan, magenta, and yellow inks. Ink is ejected at least once to WP (corresponding to step (a) of the present invention). At the same time, the control unit 43 switches to another second group GR2 when ink is ejected once on the conveyed continuous paper WP (corresponding to step (b) of the present invention). In addition, the control unit 43 causes at least one round of ink ejection by the groups GR1 and GR2 (corresponding to step (c) of the present invention). In FIG. 3B, two rounds are performed.

  As a result, as shown in FIG. 6C, each color is subjected to the lasing, and the print start mark MA1 is printed.

  Next, operations of the print heads 23a to 23d controlled by the control unit 43 will be described with reference to FIGS.

[Discharge of black ink by the first print head 23a]
In FIG. 6A, the control unit 43 controls the first print head 23a in FIG. 1 to discharge black ink. Then, the control unit 43 causes the raw infrastructure to be performed in the section SC1 adjacent to the page head position TP. It should be noted that the black ink is performed using a discharge waveform signal for raw infrasing. Cyan, magenta, and yellow ink, which will be described later, are also performed by a discharge waveform signal for lainwashing, and each color ink is subjected to lainwashing under the same conditions.

  As shown in FIG. 3B, the control unit 43 discharges black ink in a checkered pattern, for example, and performs the lainishing as shown in the printing region K2 in FIG. 6A.

  As a result, it is possible to reduce the ink adhesion amount per unit area due to the black ink. Therefore, it is possible to improve the drying property of the ink in the area L2 of the lainishing. Note that the print start mark MA1 in the section SC1 is printed by the black ink laundering.

  In the next section SC2 to section SC5, the continuation of the print start mark MA1 is printed. In the sections SC2 to SC4, there is an overlapping area K1 in which the print start mark MA1 printed with black ink and the areas C, M, and Y overlapped with ink other than black overlap. The black ink printing start mark MA1 in the section SC2 to the section SC5 is printed by a normal discharge waveform signal for printing. The printing of the printing start mark MA1 in the sections SC2 to SC4 is performed with the same ink adhesion amount per unit area as in the section SC5.

[Discharge of cyan ink by the second print head 23b]
In FIG. 6B, the control unit 43 controls the second print head 23b in FIG. 1 to discharge cyan ink. Then, the control unit 43 causes the cyan ink to perform the labyrinth in the section SC2. In the case of the cyan ink, the ink is ejected in, for example, a checkered pattern like the black ink. For this reason, it is possible to reduce the ink adhesion amount per unit area of the area C of the lainishing. As a result, the drying property of the ink can be improved in the area C of the lainishing.

  In addition, the cyan ink laundering region C overlaps with the black ink print start mark MA1 in the overlapping region K1. However, in this case, since the ink is ejected in, for example, a checkered pattern, the ink adhesion amount (ink ejection amount) per unit area is reduced in the cyan ink laminating region C. Therefore, in the overlapping region K1, the total ink adhesion amount per unit area can be reduced, and the ink drying property can be improved.

[Ejection of magenta ink and yellow ink by third and fourth print heads 23c and 23d]
In FIG. 3C, the control unit 43 controls the third print head 23c in FIG. 1 to discharge magenta ink, and controls the fourth print head 23d to discharge yellow ink. Then, the control unit 43 causes the magenta ink to perform the labyrinth in the section SC3 and performs the yellow ink for the infrastructure in the section SC4.

  In the magenta and yellow inks, the ink is ejected in, for example, a checkered pattern as in the case of the black ink. Therefore, it is possible to reduce the amount of ink attached per unit area of the lay infrasing regions M and Y. As a result, it is possible to improve the drying property of the ink in the areas M and Y of the lainishing.

  In addition, the magenta and yellow ink laminating regions M and Y overlap the black ink printing start mark MA1 in the overlapping region K1. However, since the ink is ejected, for example, in a checkered pattern in the laminating regions M and Y, the ink adhesion amount per unit area is reduced. Therefore, in the overlapping region K1, the total ink adhesion amount per unit area can be reduced, and the ink drying property can be improved.

  According to the present embodiment, the control unit 43 causes the lasing to discharge ink from all the ink jet nozzles 41 to the continuous paper WP. At that time, the control unit 43 ejects ink at least once to the conveyed continuous paper WP in, for example, the first group GR1 of one of the two groups GR1 and GR2 in which the plurality of inkjet nozzles 41 are grouped. Let At the same time, when the ink is ejected once with respect to the continuous paper WP being conveyed, the control unit 43 switches to another second group GR2. Then, the control unit 43 causes at least one round of ink ejection by the groups GR1 and GR2. As a result, the amount of ink adhering per unit area due to the lainishing can be reduced, and the drying property of the ink can be improved.

  Next, Embodiment 2 of the present invention will be described with reference to the drawings. In addition, the description which overlaps with Example 1 is abbreviate | omitted.

  In the first embodiment, as shown in FIGS. 6A to 6C, each color is subjected to lainishing, and a print start mark MA1 is printed. At this time, there is an overlapping region K1 where the laminating regions C, M, and Y of cyan, magenta, and yellow inks other than black overlap with the black ink printing start mark MA1. In the overlap area K1, the dryness is poor, but the lainness of each color is performed by ejecting ink in a checkered pattern, for example. Therefore, the total ink adhesion amount per unit area in the overlapping region K1 can be reduced. Thereby, the drying property of the ink can be improved.

  On the other hand, in the second embodiment, the ink drying property is further improved in printing the print start mark MA1.

  When the printing start mark MA1 is printed, the control unit 43 sets the ink adhesion amount per unit area for printing the black ink printing start mark MA1 in the overlapping area K1 in the area other than the overlapping area K1 and the black ink. The print start mark MA1 other than the area K2 where the lainishing is performed is reduced compared to the area K3 where the printing is performed (corresponding to step (d) of the present invention).

  That is, in the overlapping area K1 of the sections SC2 to SC4 in FIG. 6A, the ink adhesion amount per unit area of the black ink printing start mark MA1 is made smaller than the area K3 of the printing start mark MA1 in the section SC5. The printing start mark MA1 in the sections SC2 to SC5 is printed by a normal printing ejection waveform signal.

  The mark detection unit 39 presets a density threshold for mark detection using the white and black solid print images of the continuous paper WP. In the overlapping region K1 in the sections SC2 to SC4, the ink discharge amount per unit area is set so that the print images of a plurality of colors exceed the threshold, and the threshold is set. On the other hand, the area K3 of the printing start mark MA1 in the section SC5 is an area that does not overlap with colors other than black. The area K3 is printed only with black ink. Therefore, the ink discharge amount (density) per unit area is set in the area K3 of the section SC5 such that the detection of the print start mark MA1 by the mark detection unit 39 is not impaired.

  According to the present embodiment, when the printing start mark MA1 is printed, the control unit 43 sets the ink adhesion amount per unit area for printing the printing start mark MA1 in the overlapping area K1 except for the overlapping area K1. In addition, the print start mark MA1 other than the area K2 where the black ink is subjected to the laundering is reduced compared to the area K3 where the printing is started. Thereby, in the overlap region, the ink adhesion amount per unit area of the page information mark can be reduced. Therefore, in the overlapping area, it is possible to reduce the ink adhesion amount per unit area for both printing of the page information mark and the lainishing, and further, it is possible to improve the drying property of the ink in the overlapping area.

  Further, the ink discharge amount per unit area of the black ink printing start mark MA1 in the overlapping area K1 is smaller than that in the area K3 of the printing start mark MA1 other than the overlapping area K1 and other than the laminating area K2. However, the laminating is performed on the overlapping area K1 with inks of colors other than black (cyan, magenta, yellow, etc.). Therefore, even if the density of the print start mark MA1 in the overlapping area K1 decreases, the density necessary for mark detection can be compensated.

  The present invention is not limited to the above embodiment, and can be modified as follows.

  (1) In each of the above-described embodiments, the information of the page top position of the continuous paper WP is shown, and the print start mark MA1 is described as an example of the page start position mark printed from the page top position. However, the present invention is not limited to this. . For example, the page head position mark may be a cutter mark MA2 for a processing machine that cuts the continuous paper WP after printing by the printing apparatus 1 as shown in FIG. The cutter mark MA2 is arranged on the downstream side of the continuous paper WP from the page head position TP, and is arranged at a position on the continuous paper WP other than both ends in the width direction 202 of the continuous paper WP.

  According to the page head position mark including the print start mark MA1, the cutter mark MA2, and the like, it is possible to improve the drying property of the ink when there is an overlapping area that overlaps between the print area of the page head position mark and the laminating area. . In FIG. 7, the print start mark MA1 and the cutter mark MA2 are printed. However, the print start mark MA1 may not be printed if necessary.

  (2) In each of the above-described embodiments and modification (1), the page head position mark including the print start mark MA1, the cutter mark MA2, and the like has been described as an example of the page information mark indicating the page information of the continuous paper WP. However, it is not limited to this. For example, the mark may not be printed from the page top position.

  (3) In each of the above-described embodiments, in the above-described embodiments and modifications, the front surface printing unit 5 performs printing of the print start mark MA1, the cutter mark MA2, and the like, and the lainishing, but the back surface printing. The unit 9 may also perform at least one of printing of the cutter mark MA2 and the like and raw lancing.

  (4) In each of the above-described embodiments and modifications, the print start mark MA1 is printed with black ink, but may be ink of a color other than black as long as the mark detection unit 39 can detect it. As a result, when there is an overlap area K1 between the print start mark MA1 printed with ink of a color other than black and the area of the lainishing, it is possible to improve the drying property of the ink.

  (5) In each of the above-described embodiments and modifications, the labyrinth process discharges ink from all the inkjet nozzles 41 provided. In this regard, ink may be ejected from the inkjet nozzles 41 related to all image printing (related to printing) without ejecting ink from all the inkjet nozzles 41 provided.

  As shown in FIGS. 2A and 2B, in the width direction 202 of the continuous paper WP, the width of the plurality of inkjet nozzles 41 of the print head 23 may be larger than the width of the continuous paper WP. In this case, if the print quality by the ink jet nozzles 41 used during the printing operation is not adversely affected, it is not necessary to drive the ink jet nozzles 41 not used during the printing operation at the time of the labyrinth.

  For this reason, the control unit 43 causes the continuous paper WP to perform a lasing that ejects ink from the inkjet nozzles 41 necessary for maintaining the print quality, that is, all the inkjet nozzles 41 related to image printing. In other words, the control unit 43 causes the lainness to be performed without using the inkjet nozzle 41 disposed outside the width W1 of the continuous paper WP or the preset width W1 including the width of the continuous paper WP. . At this time, the control unit 43 may group a plurality of inkjet nozzles 41 related to image printing.

  (6) In each of the above-described embodiments and modifications, as shown in FIGS. 2A and 2B, the plurality of inkjet nozzles 41 of the print head 23 have a length that is equal to or greater than the width of the continuous paper WP. And arranged over the width direction 202 of the continuous paper WP. In this regard, the plurality of inkjet nozzles 41 may have a length less than the width of the continuous paper WP.

  (7) In each of the above-described embodiments and modifications, for example, in FIG. 3B, ink is continuously ejected at a predetermined timing in one of the two groups GR1 and GR2. However, for example, between the two groups GR1 and GR2 in FIG. 3B or between the two groups GR1 and GR2 or while ejecting ink twice in succession in the transport direction 201 of the first group GR1 in FIG. You may provide the time at which GR1 and GR2 do not discharge ink at least once.

  (8) In each embodiment and each modification described above, the continuous paper WP is made of paper, but may be, for example, a resin sheet.

DESCRIPTION OF SYMBOLS 1 ... Inkjet printer 19, 31 ... Printing part 23 (23a-23d) ... Print head 37 (37a-37d) ... Print head 41 ... Inkjet nozzle 43 ... Control part 201 ... Conveyance direction 202 ... Width direction WP ... Continuous paper MA1 … Print start mark (and its area)
MA2 ... Cutter mark (and its area)
K (K1 to K3): Black ink (and its area)
K1 ... Overlapping area C ... Cyan ink (and its area)
M: Magenta ink (and its area)
Y ... Yellow ink (and its area)
SC1 to SC5 ... Section TP ... Page top position GR1 to GR3 ... Group

Claims (4)

An inkjet printing method for printing an image by ejecting ink onto a transported print medium,
A control unit that controls a print head in which a plurality of inkjet nozzles that eject ink are arranged in a width direction intersecting with a conveyance direction of the print medium,
Performing a labyrinsing process for performing lainwashing to eject ink from the inkjet nozzles related to all image printing on the transported print medium;
The raw infiltration process includes:
(A) ejecting ink at least once on the transported print medium in any of two or more groups obtained by grouping the plurality of inkjet nozzles;
(B) causing the step (a) to be performed, and in the case where ink is ejected a preset number of times to the transported print medium, the step of changing to another group;
(C) having at least one round of ink ejection by each group of the step (a) and the step (b) ,
The control unit is a mark printing step for printing a page information mark indicating information of a page of the print medium on the transported print medium, which is performed together with the lainishing, and is set in advance. The page information mark is printed so that there is an overlapping area in which an area where the page information mark is printed with color ink and an area where the lainwashing is performed with ink of a color other than the color are present. An ink-jet printing method comprising performing a mark printing step . The inkjet printing method according to claim 1, wherein
The inkjet printing method according to claim 1, wherein the inkjet nozzles of each group are arranged in every other one or more. The inkjet printing method according to claim 1 , wherein
In the mark printing step, (d) when the page information mark is printed, an ink adhesion amount per unit area for printing the page information mark in the overlapping area is set to a value other than the overlapping area and the line. An ink jet printing method comprising a step of reducing the page information mark other than the area where flushing is performed, compared to the area where the page information mark is printed. An inkjet printing apparatus that prints an image by ejecting ink onto a transported print medium,
A plurality of inkjet nozzles that eject ink, the print heads being arranged in a width direction intersecting the transport direction of the print medium;
A control unit for controlling the print head,
The controller causes the labyrinth to eject ink from the inkjet nozzles related to all image printing on the transported print medium,
The control unit causes the ink to be ejected at least once to the transported print medium in any of two or more groups obtained by grouping the plurality of inkjet nozzles when performing the lainishing. When the ink is ejected a preset number of times for the print medium to be conveyed, the other group is replaced, and at least one round of ink ejection by each group is performed ,
The control unit further includes an area where the page information mark is printed with ink of a preset color on the transported print medium together with the lainishing, and the ink of a color other than the color. An ink jet printing apparatus that prints a page information mark indicating information on a page of the print medium so that there is an overlapping area that overlaps an area in which laundering is performed .

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