Inkjet printing equipment

Abstract

In a serial inkjet printing system that prints on multiple printing media, it is possible to print with different print resolutions for each printing medium in the direction of transport of the printing media within a single print job. [Solution] The control unit controls the inkjet head 41 to print an image on the printing media 11A and 11B by alternately performing the operation of ejecting ink onto the printing media 11A and 11B based on the print job while moving the inkjet head 41 in the main scanning direction, and the operation of transporting the printing media 11A and 11B by the transport unit 2. The control unit adjusts the amount of transport by the transport unit 2 in the operation of transporting the printing media 11A and 11B so that the amount of transport by the transport unit 2 is smaller for the printing media 11A and 11B, and controls the inkjet head 41 so that the pitch of the dots formed by the ink ejected by the inkjet head 41 in the sub-scanning direction becomes smaller for the printing media 11A and 11B with a smaller transport amount by the transport unit 2.

Description

Technical Field

[0006] , ,

[0005] , ,

[0007] ,

[0001] The present invention relates to an inkjet printing apparatus.

Background Art

[0002] There is known a serial type inkjet printing apparatus that ejects ink from an inkjet head onto a printing medium while moving the inkjet head to perform printing.

[0003] Among this type of inkjet printing apparatus, there are some in which a plurality of printing medium rolls are arranged side by side in the direction in which the inkjet head moves, and printing can be performed simultaneously on a plurality of printing media pulled out from the plurality of printing medium rolls (see Patent Document 1).

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] In the inkjet printing apparatus as described above, printing is performed on a plurality of printing media by alternately performing an operation of printing on a plurality of printing media while moving the inkjet head and an operation of conveying the plurality of printing media, thereby performing printing on a plurality of printing media in one printing job. <00000​​​​​The present invention has been made in view of the above, and aims to enable a serial inkjet printing apparatus that prints on multiple printing media to print with different printing resolutions in the transport direction of each printing medium in a single print job. [Means for solving the problem]

[0008] To achieve the above objective, the inkjet printing apparatus of the present invention comprises an inkjet head movable in the main scanning direction, a transport unit that transports a plurality of printing media arranged in parallel in the main scanning direction in a sub-scanning direction perpendicular to the main scanning direction and can individually adjust the transport amount of each printing media, and a control unit that controls the inkjet head to print an image on the plurality of printing media by alternately performing the operation of ejecting ink onto the plurality of printing media based on a print job while moving the inkjet head in the main scanning direction and the operation of transporting the plurality of printing media by the transport unit, wherein the control unit adjusts the transport amount by the transport unit for each printing medium and controls the inkjet head so that the pitch of dots formed by the ink ejected by the inkjet head in the sub-scanning direction becomes smaller for printing media with smaller transport amounts. [Effects of the Invention]

[0009] According to the present invention, in a serial inkjet printing apparatus that prints on multiple printing media, it is possible to print with different printing resolutions for each printing medium in the transport direction of the printing media within a single printing job. [Brief explanation of the drawing]

[0010] [Figure 1] This is a perspective view showing the schematic configuration of an inkjet printing apparatus according to the first embodiment. [Figure 2] Figure 1 is a side view showing the schematic configuration of the inkjet printing apparatus. [Figure 3] Figure 1 is a side view of the main components of the inkjet printing apparatus shown. [Figure 4]Figure 1 is a plan view of the main components of the inkjet printing apparatus shown. [Figure 5] Figure 1 is a control block diagram of the inkjet printing apparatus. [Figure 6] This is a timing chart illustrating an example of how the transport unit transports the printing medium. [Figure 7] This is a diagram illustrating the printing process for each pass. [Figure 8] This is a diagram illustrating the printing process for each pass. [Figure 9] This is a diagram illustrating the printing process for each pass. [Figure 10] This is a diagram illustrating the printing process for each pass. [Figure 11] This is a diagram illustrating the printing process for each pass. [Figure 12] This is a diagram illustrating the printing process for each pass. [Figure 13] This figure shows a dot image of an image printed on a print medium. [Figure 14] This is a side view of the main part of an inkjet printing apparatus according to the second embodiment. [Modes for carrying out the invention]

[0011] Embodiments of the present invention will be described below with reference to the drawings. Throughout the drawings, the same or equivalent parts and components are denoted by the same or equivalent reference numerals.

[0012] The embodiments shown below illustrate devices and the like that embody the technical concept of this invention, and the technical concept of this invention does not specify the material, shape, structure, arrangement, etc., of each component as described below. The technical concept of this invention can be modified in various ways within the scope of the claims.

[0013] [First Embodiment] FIG. 1 is a perspective view showing a schematic configuration of an inkjet printing apparatus according to a first embodiment of the present invention. FIG. 2 is a side view showing the schematic configuration of the inkjet printing apparatus shown in FIG. 1. FIG. 3 is a side view of a main part of the inkjet printing apparatus shown in FIG. 1. FIG. 4 is a plan view of a main part of the inkjet printing apparatus shown in FIG. 1. FIG. 5 is a control block diagram of the inkjet printing apparatus shown in FIG. 1. In the following description, the up, down, left, right, front, and rear directions indicated by the arrows in FIG. 1 are defined as the up, down, left, right, front, and rear directions in the inkjet printing apparatus.

[0014] As shown in FIGS. 1 to 5, an inkjet printing apparatus 1 according to the first embodiment includes a conveyance unit 2, a platen 3, a fan 4, a main scanning drive guide 5, a main scanning drive motor 6, a head unit 7, and a control unit 8.

[0015] The conveyance unit 2 conveys two printing media 11A and 11B made of a belt-like sheet or the like. The conveyance unit 2 includes a printing medium roll holding unit 12, a conveyance roller (corresponding to a driving roller) 13, a conveyance drive motor 14, two nip rollers 15A and 15B, two nip release mechanism units 16A and 16B, a take-up shaft holding unit 17, take-up shafts 18A and 18B, take-up drive motors 19A and 19B, and guide members 20 and 21. Note that the alphabetic subscripts in the symbols such as 11A and 11B of the printing media may be omitted and collectively represented.

[0016] The printing medium roll holding unit 12 rotatably holds two printing medium rolls 31A and 31B. The printing medium rolls 31A and 31B are formed by winding printing media 11A and 11B around cores 32A and 32B in a roll shape, respectively.

[0017] In the printing medium roll holding unit 12, the printing medium rolls 31A and 31B are arranged in parallel in the left-right direction (main scanning direction). The printing medium roll 31B is arranged on the left side of the printing medium roll 31A.

[0018] The core 32 of the printing medium roll 31 is subjected to rotational resistance such that it rotates due to the transport force of the printing medium 11 by the transport rollers 13 and nip rollers 15, but does not rotate due to the force of winding the printing medium 11 onto the winding shaft 18 by the winding drive motor 19.

[0019] The transport roller 13 nips the printing media 11A and 11B between itself and the nip rollers 15A and 15B, and is rotated to transport the printing media 11A and 11B toward the platen 3. The transport roller 13 is located near the rear of the platen 3.

[0020] The transport direction of the printing medium 11 by the transport roller 13 and the nip roller 15 is from the rear to the front in the front-to-back direction (sub-scanning direction), which is perpendicular to the left-to-right direction (main scanning direction).

[0021] The transport drive motor 14 rotates the transport roller 13.

[0022] The nip rollers 15A and 15B are provided corresponding to the printing media 11A and 11B, respectively, and nip the printing media 11A and 11B between them and the transport roller 13 to transport the printing media 11A and 11B.

[0023] In this embodiment, the nip roller 15 consists of three unit rollers 15a arranged in parallel in the left-right direction, as shown in Figure 4. However, the nip roller 15 may also consist of a single roller.

[0024] The nip roller 15 is configured to be movable between the nip position shown by the solid line in Figure 3 and the nip release position shown by the dashed line.

[0025] The nip position of the nip roller 15 is the position where the nip roller 15 nips the printing medium 11 between itself and the transport roller 13. In the nip state, positioned at the nip position, the nip roller 15 nips the printing medium 11 between itself and the rotationally driven transport roller 13, thereby transporting the printing medium 11. At this time, the nip roller 15 rotates in accordance with the transport roller 13.

[0026] The nip release position of the nip roller 15 is above the nip position, and is the position where the nip roller 15 moves away from the printing medium 11 and releases the nip of the printing medium 11 between it and the transport roller 13. In the nip release state, when the nip roller 15 is positioned in the nip release position, the printing medium 11 corresponding to the nip roller 15 is not transported even if the transport roller 13 is rotated.

[0027] The nip release mechanisms 16A and 16B move the nip rollers 15A and 15B, respectively, between the nip position and the nip release position. This allows for individual switching between the nip state and the nip release state of the nip rollers 15A and 15B. By switching between the nip state and the nip release state of the nip rollers 15A and 15B, the nip release mechanisms 16A and 16B can individually adjust the amount of printing media 11A and 11B being transported. The nip release mechanism 16 includes a mechanism for raising and lowering the nip roller 15 using a cam system or the like, and a motor (neither shown) that drives this mechanism.

[0028] The winding shaft holding section 17 rotatably holds the two winding shafts 18A and 18B. In the winding shaft holding section 17, the winding shafts 18A and 18B are arranged in parallel in the left-right direction, with winding shaft 18B positioned to the left of winding shaft 18A.

[0029] The winding shafts 18A and 18B each wind up the printing media 11A and 11B that have been drawn from the printing media rolls 31A and 31B and transported via the platen 3. The winding shafts 18A and 18B are located below the front of the platen 3.

[0030] The winding drive motors 19A and 19B rotate the winding shafts 18A and 18B, respectively.

[0031] Guide member 20 guides the printing media 11A and 11B upstream of the transport roller 13 in the transport direction of the printing media 11A and 11B. Guide member 21 guides the printing media 11A and 11B downstream of the platen 3.

[0032] The platen 3 supports the printing media 11A and 11B. The platen 3 is positioned directly below the area from which ink is ejected by the head unit 7 of the printing media 11A and 11B. The platen 3 is formed in an elongated shape that extends in the left-right direction. The platen 3 has a plurality of air intake holes (not shown) formed therein.

[0033] The fan 4 draws air through the suction holes in the platen 3, generating an adhesive force at the suction holes and causing the printing media 11A and 11B to adhere to the platen 3. This suppresses the lifting of the printing media 11A and 11B from the platen 3, and prevents them from colliding with the inkjet head 41, which will be described later.

[0034] The main scan drive guide 5 guides the head unit 7 to move in the main scan direction (left-right direction). The main scan drive guide 5 is formed in an elongated shape that extends in the left-right direction.

[0035] The main scanning drive motor 6 moves the head unit 7 in the main scanning direction.

[0036] The head unit 7 moves in the main scanning direction and ejects ink onto the printing media 11A and 11B to perform printing. The head unit 7 is movable between a position to the right of the right edge of the printing medium 11A and a position to the left of the left edge of the printing medium 11B. As shown in Figure 3, the head unit 7 includes an inkjet head 41 and a carriage 42.

[0037] The inkjet head 41 has a nozzle surface 41a, which is the lower surface facing the platen 3, and has a plurality of nozzles (not shown) arranged along the front-to-back direction (sub-scanning direction), and ejects ink from the nozzles.

[0038] The carriage 42 holds the inkjet head 41.

[0039] The control unit 8 controls the operation of the entire inkjet printing device 1. The control unit 8 is composed of a CPU, RAM, ROM, hard disk, etc.

[0040] Specifically, the control unit 8 moves the head unit 7 in the main scanning direction and, based on the print job, ejects ink from the inkjet head 41 to the print media 11A and 11B to perform one pass of printing, after which the transport unit 2 transports the print media 11A and 11B forward. Next, the control unit 8 moves the head unit 7 in the opposite direction to the previous pass and performs the next pass of printing, after which the transport unit 2 transports the print media 11A and 11B forward. The control unit 8 alternates between this one-pass printing operation and the operation of transporting the print media 11A and 11B to print an image on the print media 11A and 11B.

[0041] In this process, the control unit 8 adjusts the amount of material transported by the transport unit 2 during the transport of the printing media 11A and 11B so that the amounts transported by the transport unit 2 are different for printing media 11A and 11B. The control unit 8 also controls the inkjet head 41 so that the pitch of the dots formed by the ink ejected by the inkjet head 41 in the sub-scanning direction becomes smaller for the printing media 11A or 11B that is transported by the transport unit 2.

[0042] Next, the printing operation of the inkjet printer 1 will be described.

[0043] When a print job is input from an external device such as a personal computer, the control unit 8 starts driving the fan 4.

[0044] Next, the control unit 8 controls the main scanning drive motor 6 to move the head unit 7 to the left or right, and controls the inkjet head 41 based on the print job to eject ink onto the printing media 11A and 11B, thereby performing the first pass of printing.

[0045] In the first pass, printing is performed on the printing media 11A and 11B in an area with a width (length in the sub-scanning direction) equivalent to the amount of each medium 11A and 11B transported in one pass. Details of the printing operation for each pass will be described later.

[0046] Once the first pass of printing is complete, the control unit 8 causes the transport unit 2 to transport the printing media 11A and 11B forward. At this time, the control unit 8 adjusts the amount of each printing medium 11A and 11B transported by the transport unit 2 according to the printing resolution in the sub-scanning direction (the transport direction of the printing medium 11) of the image to be printed on each printing medium 11A and 11B. The higher the printing resolution in the sub-scanning direction, the smaller the amount of the printing medium 11 is transported, and the smaller the pitch of the dots in the sub-scanning direction.

[0047] An example of the operation by which the transport unit 2 transports the printing media 11A and 11B will be explained with reference to the timing chart in Figure 6. This example is one in which the image printed on printing media 11A has a higher print resolution in the sub-scanning direction than the image printed on printing media 11B.

[0048] At time t1 in Figure 6, when the printing operation for one pass is completed (turned off), at the following time t2, the control unit 8 starts driving (turns on) the transport roller 13.

[0049] Here, both nip rollers 15A and 15B are in the nip position. As a result, the transport roller 13 drives the printing media 11A and 11B, which are pulled out from the printing media rolls 31A and 31B as they are transported.

[0050] When the amount of printing media 11A and 11B transported from time t2 reaches a predetermined amount corresponding to the printing resolution in the sub-scanning direction of the image to be printed on printing media 11A, the control unit 8 stops (turns off) the transport roller 13 at time t3. This stops the transport of printing media 11A and 11B. At this point, the slack printing media 11A and 11B that have been transported by the transport roller 13 and nip rollers 15A and 15B are wound onto the winding shafts 18A and 18B.

[0051] After stopping the transport roller 13 at time t3, at time t4, the control unit 8 moves the nip roller 15A to the nip release position. This switches the nip roller 15A from the nip state to the nip release state.

[0052] Next, at time t5, the control unit 8 starts driving the transport roller 13. This causes the printing medium 11B to be transported. However, since the nip roller 15A is in the nip release state, the printing medium 11A is not transported even when the transport roller 13 is driven. Furthermore, the printing medium 11A is held in place by the suction force generated by the drive of the fan 4, so the position of the printing medium 11A is maintained.

[0053] When the sum of the amount of printing medium 11B transported during the period from time t2 to t3 and the amount of printing medium 11B transported from time t5 reaches a predetermined transport amount corresponding to the printing resolution in the sub-scanning direction of the image to be printed on the printing medium 11B, the control unit 8 stops the transport roller 13 at time t6. This stops the transport of the printing medium 11B. At this point, the slackened printing medium 11B that has been transported by the transport roller 13 and the nip roller 15B is wound onto the winding shaft 18B.

[0054] At time t6, the transport roller 13 is stopped, and at time t7, the control unit 8 moves the nip roller 15A to the nip position. This switches the nip roller 15A from the released nip state to the nip state. At time t8, the printing operation for the next pass is started.

[0055] As described above, in the example shown in Figure 6, the nip roller 15B maintains a nip state, and the nip roller 15A is switched from a nip state to a nip release state in the middle of the transport operation, thereby adjusting so that the amount of print medium 11A transported is smaller than that of print medium 11B.

[0056] Furthermore, when switching the nip roller 15A from the nip state to the nip release state, the transport roller 13 is stopped (times t3 to t5). This allows for more precise adjustment of the amount of printing medium 11A transported compared to when the nip roller 15A is switched from the nip state to the nip release state while the transport roller 13 is still running.

[0057] Once the transport operation of the printing media 11A and 11B after the printing operation of the first pass is completed, the control unit 8 moves the head unit 7 in the opposite direction to the first pass and controls the inkjet head 41 based on the print job to eject ink onto the printing media 11A and 11B, thereby performing the printing of the second pass.

[0058] Once the printing operation of the second pass is completed, the control unit 8 causes the transport unit 2 to transport the printing media 11A and 11B forward, just as it did after the printing operation of the first pass.

[0059] Similarly thereafter, the control unit performs printing on the printing media 11A and 11B by alternately repeating the printing operation for one pass and the transport operation of the printing media 11A and 11B.

[0060] Next, we will explain the printing process for each pass in the printing operation described above.

[0061] In the inkjet printing apparatus 1, for each of the printing media 11A and 11B, an area with a width (length in the sub-scanning direction) equivalent to the amount transported per pass is printed in a predetermined number of passes according to the printing resolution in each sub-scanning direction.

[0062] For example, if the print resolution of print medium 11A in the sub-scanning direction is twice that of print medium 11B, then for print medium 11A, an area with a width equivalent to the amount transported per pass is printed in 8 passes, and for print medium 11B, an area with a width equivalent to the amount transported per pass is printed in 4 passes. In this case, the amount transported per pass for print medium 11A is half that of print medium 11B.

[0063] In this example, the first printing pass is performed on area Ra1 of printing medium 11A and area Rb1 of printing medium 11B, as shown in Figure 7. The widths of areas Ra1 and Rb1 are equivalent to the amount of material transported per pass on printing mediums 11A and 11B, respectively. The same applies to the widths of areas Ra2-Ra8 and Rb2-Rb8, which will be described later. In the first printing pass, some dots (pixels) are formed in each of areas Ra1 and Rb1. The dots formed in each pass will be described later.

[0064] In the second printing pass, as shown in Figure 8, printing is performed on areas Ra1 and Ra2 of the printing medium 11A and areas Rb1 and Rb2 of the printing medium 11B, forming some dots in each of the areas Ra1, Ra2, Rb1, and Rb2.

[0065] In the third printing pass, printing is performed on areas Ra1-Ra3 of printing medium 11A (see Figure 9) and areas Rb1-Rb3 of printing medium 11B (see Figure 9), forming some dots in areas Ra1-Ra3 and Rb1-Rb3, respectively. Note that the illustration of the state of the printed images on printing mediums 11A and 11B at the end of the third pass is omitted.

[0066] In the fourth printing pass, printing is performed on areas Ra1 to Ra4 of printing medium 11A (see Figure 9) and areas Rb1 to Rb4 of printing medium 11B (see Figure 9), forming some dots in areas Ra1 to Ra4 and Rb1 to Rb4, respectively. As a result, as shown in Figure 9, printing of area Rb1 of printing medium 11B is completed. Area Rb1 has been printed in four passes, from the first to the fourth pass.

[0067] In the fifth printing pass, printing is performed on areas Ra1 to Ra5 ​​(see Figure 10) of printing medium 11A and areas Rb2 to Rb4 of printing medium 11B, forming some dots in areas Ra1 to Ra5 ​​and Rb2 to Rb4, respectively. This completes the printing of areas Rb1 and Rb2 of printing medium 11B. Area Rb2 has been printed in the four passes from the second to the fifth pass.

[0068] In the sixth printing pass, printing is performed on areas Ra1 to Ra6 of printing medium 11A (see Figure 10) and areas Rb3 and Rb4 of printing medium 11B, forming some dots in each of these areas. This completes the printing of areas Rb1 to Rb3 on printing medium 11B. Area Rb3 has been printed in the four passes from the third to the sixth pass.

[0069] Note that the illustrations showing the state of the printed images on printing media 11A and 11B at the end of the 5th and 6th passes, respectively, have been omitted.

[0070] In the seventh printing pass, printing is performed on areas Ra1 to Ra7 (see Figure 10) of the printing medium 11A and area Rb4 of the printing medium 11B, forming some dots in areas Ra1 to Ra7 and Rb4, respectively. When the seventh printing pass is completed, as shown in Figure 10, the printing of one page (areas Rb1 to Rb4) of the image on the printing medium 11B is complete. Area Rb4 was printed in the four passes from the fourth to the seventh pass.

[0071] In the eighth printing pass, printing is performed on areas Ra1 to Ra8 (see Figure 11) of the printing medium 11A, forming some dots in each of these areas. As a result, as shown in Figure 11, printing of area Ra1 of the printing medium 11A is completed. Area Ra1 has been printed in eight passes, from the first to the eighth. After this eighth pass, no further printing is performed on the printing medium 11B.

[0072] Here, after the completion of the 7th print pass, the print medium 11B is not transported, and only the print medium 11A is transported in each pass. That is, while the print medium 11A is being transported with the nip roller 15A in the nip state, the nip roller 15B is released from the nip state.

[0073] In the 9th to 15th printing passes, printing is performed on areas Ra2 to Ra8 of the printing medium 11A in the same manner as printing on areas Rb2 to Rb4 of the printing medium 11B in the 5th to 7th printing passes described above. As a result, printing on areas Ra2 to Ra8 of the printing medium 11A is sequentially completed by the 9th to 15th printing passes.

[0074] When the 15th printing pass is completed, as shown in Figure 12, the printing of one page (area Ra1 to Ra8) of the image on the printing medium 11A is complete. Note that the illustrations of the printed images on the printing mediums 11A and 11B at the end of each of the 9th to 14th passes are omitted.

[0075] Regions Ra2 to Ra8, like region Ra1, were each printed in 8 passes. For example, region Ra2 was printed in 8 passes, from the 2nd to the 9th pass. Similarly, region Ra8 was printed in 8 passes, from the 8th to the 15th pass.

[0076] In the examples shown in Figures 7 to 12 above, printing on the printing medium 11B was completed after one page. However, if a second page needs to be printed on the printing medium 11B, the printing of the second page may be started while the first page of the printing medium 11A is still printing.

[0077] Figure 13 shows the dot images of the images printed on printing media 11A and 11B, respectively, in the examples shown in Figures 7 to 12 above. Figure 13 shows the dot images of some of the regions Ra1 and Ra2 of the image printed on printing media 11A, and the dot images of some of the region Rb1 of the image printed on printing media 11B.

[0078] In this example, the print resolution in the main scanning direction (left-right direction) of the images printed on printing media 11A and 11B is assumed to be the same as the print resolution in the sub-scanning direction (transport direction of printing medium 11) of the respective images. Furthermore, the density of the printed images is assumed to be the same for the image printed on printing medium 11A and the image printed on printing medium 11B.

[0079] In Figure 13, the numbers written inside each dot Da, Db indicate the order of the paths in which that dot Da, Db was formed. Here, for each dot Da in region Ra2, the number indicates the order of the paths starting from the first path printed in region Ra2. That is, as mentioned above, the first path printed in region Ra2 is the second path overall, so the dots Da "1" to "8" in region Ra2 in Figure 13 were formed in the 2nd to 9th paths, respectively.

[0080] In the printing operations shown in the examples in Figures 7 to 12 above, as shown in Figure 13, in the printing operation of each pass, dots Da and Db corresponding to the pass are formed sequentially, and printing is completed in 8 passes for areas Ra1 and Ra2, and in 4 passes for area Rb1. The same applies to areas Ra3 to Ra8 and Rb2 to Rb4, which are not shown in Figure 13.

[0081] Dot Da is formed at a pitch that is half the pitch of dot Db in both the main scanning direction and the sub-scanning direction. That is, in both the main scanning direction and the sub-scanning direction, dots are formed on the printing medium 11A at half the pitch of the printing medium 11B. As a result, in both the main scanning direction and the sub-scanning direction, the printing medium 11A is printed at twice the printing resolution of the printing medium 11B.

[0082] In this example, the amount of ink ejected for dot Da is set to be smaller than the amount of ink ejected for dot Db, so that regions Ra1-Ra8 and Rb1-Rb4 are printed at the same density.

[0083] As described above, in the inkjet printing apparatus 1, the control unit 8 adjusts the amount of material transported by the transport unit 2 during the transport operation of the printing media 11A and 11B so that the amount of material transported by the transport unit 2 is different for printing media 11A and 11B. Furthermore, the control unit 8 controls the inkjet head 41 so that the pitch of the dots formed by the ink ejected by the inkjet head 41 in the sub-scanning direction becomes smaller for the printing media 11A or 11B that is transported by the transport unit 2. This makes it possible to print with different print resolutions in the sub-scanning direction for each printing medium 11 in a single print job.

[0084] Furthermore, in the inkjet printing apparatus 1, the transport unit 2 can individually switch between the nip state and the nip release state of the nip rollers 15A and 15B. By switching between the nip state and the nip release state of the nip rollers 15A and 15B, the transport unit 2 individually adjusts the transport amount of the printing media 11A and 11B. This makes it possible to adjust the transport amount for each printing medium 11.

[0085] Furthermore, in the inkjet printing apparatus 1, when switching the nip roller 15 from the nip state to the nip release state, the transport roller 13 is stopped. This allows for more precise adjustment of the amount of printing medium 11 transported compared to when the nip roller 15 is switched from the nip state to the nip release state while the transport roller 13 is still running.

[0086] [Second Embodiment] Next, a second embodiment, which modifies part of the first embodiment described above, will be explained.

[0087] In the second embodiment, the nip rollers 15A and 15B are configured to be movable between the nip position shown by the solid line in Figure 14 and the guide pressing position shown by the dashed line.

[0088] In the second embodiment, the nip position of the nip roller 15 is the same as in the first embodiment.

[0089] The guide pressing position of the nip roller 15 is the position where the printing medium 11 is pressed against the guide member 20. In the second embodiment, the nip rollers 15A and 15B are individually movable between the nip position and the guide pressing position by two corresponding sliding mechanisms (not shown).

[0090] In the second embodiment, the control unit 8 positions the nip roller 15 at the guide pressing position when the nip of the printing medium 11 between it and the transport roller 13 is released. This makes it easier to maintain the position of the printing medium 11 by pressing the non-transported printing medium 11 against the guide member 20.

[0091] [Other embodiments] As described above, the present invention has been described by first and second embodiments, but the descriptions and drawings that constitute part of this disclosure should not be understood as limiting the invention. Various alternative embodiments, examples and operational techniques will become apparent to those skilled in the art from this disclosure.

[0092] In the first and second embodiments described above, a serial inkjet printing apparatus 1 that prints on two printing media 11A and 11B was described. However, the number of printing media is not limited to two. A serial inkjet printing apparatus that prints on multiple printing media arranged in parallel in the main scanning direction is also acceptable, as long as the transport amount by the transport unit is adjusted for each printing medium, and the inkjet head is controlled so that the pitch of the dots formed by the ink ejected by the inkjet head in the sub-scanning direction becomes smaller for printing media with smaller transport amounts.

[0093] In the first and second embodiments described above, the transport roller 13 was stopped when switching the nip roller 15 from the nip state to the nip release state. However, the nip roller 15 may be switched from the nip state to the nip release state while the transport roller 13 is still being driven.

[0094] In the first and second embodiments described above, the transport unit 2 transports the printing media 11A and 11B by nipping them between the transport roller 13 and the nip rollers 15A and 15B. Furthermore, the amount of printing media 11A and 11B transported can be individually adjusted by switching between the nip state and the release state of the nip rollers 15A and 15B. However, the transport unit is not limited to this, and can transport multiple printing media in the sub-scanning direction, as long as the amount of each printing medium transported can be individually adjusted.

[0095] Thus, it goes without saying that the present invention includes various embodiments and the like that are not described herein. Therefore, the technical scope of the present invention is defined solely by the inventive features relating to the claims that are reasonable based on the above description.

[0096] [Note] This application discloses the following invention:

[0097] (Note 1) An inkjet head that can move in the main scanning direction, A transport unit that transports multiple printing media arranged in parallel in the main scanning direction in a sub-scanning direction perpendicular to the main scanning direction, and allows for individual adjustment of the transport amount of each printing medium, The system includes a control unit that alternately performs the operation of ejecting ink onto the plurality of printing media based on a print job while moving the inkjet head in the main scanning direction, and the operation of transporting the plurality of printing media using the transport unit, thereby controlling the printing of an image onto the plurality of printing media. The control unit adjusts the amount of material transported by the transport unit for each printing medium, and controls the inkjet head so that the pitch of the dots formed by the ink ejected by the inkjet head in the sub-scanning direction becomes smaller for printing media with smaller transport amounts.

[0098] (Note 2) The aforementioned transport unit is A drive roller that is driven to rotate, Each of the aforementioned plurality of printing media is provided with a plurality of nip rollers that nip the printing media between themselves and the drive roller to transport the printing media, The plurality of nip rollers can individually switch between a nip state, where the printing medium is nipped between them and the drive roller, and a nip release state, The inkjet printing apparatus according to Appendix 1, characterized in that the amount of each printing medium transported is adjusted by switching between a nip state and a nip release state at each nip roller.

[0099] (Note 3) The aforementioned transport unit is The system further includes a guide member that guides the plurality of printing media upstream of the drive roller in the transport direction of the printing media, The inkjet printing apparatus according to Appendix 2, characterized in that the nip roller in the nip-released state is positioned to press the printing medium against the guide member.

[0100] (Note 4) The inkjet printing apparatus according to Appendix 2 or 3, characterized in that the control unit stops the drive roller when switching any of the nip rollers from a nip state to a nip release state. [Explanation of Symbols]

[0101] 1. Inkjet printing device 2. Conveying section 3 Platen 4 Fans 5 Main scanning drive guide 6. Main scanning drive motor 7 Head Unit 8 Control Unit 11,11A,11B Print media 12 Print media roll holding section 13 Conveyor rollers 14. Transport drive motor 15, 15A, 15B Nipple Roller 15a Unit Roller 16,16A,16B Nip release mechanism section 17 Winding shaft holding part 18, 18A, 18B winding shaft 19, 19A, 19B Winding drive motor 20,21 Guide members 31, 31A, 31B Print media rolls 32,32A,32B core body 41 Inkjet heads 42 Carriage

Claims

1. An inkjet head that can move in the main scanning direction, A transport unit that transports multiple printing media arranged in parallel in the main scanning direction in a sub-scanning direction perpendicular to the main scanning direction, and allows for individual adjustment of the transport amount of each printing medium, The system includes a control unit that alternately performs the operation of moving the inkjet head in the main scanning direction and ejecting ink onto the plurality of printing media based on a print job, and the operation of transporting the plurality of printing media using the transport unit, thereby controlling the printing of an image onto the plurality of printing media. The control unit adjusts the amount of material transported by the transport unit for each printing medium, and controls the inkjet head so that the pitch of the dots formed by the ink ejected by the inkjet head in the sub-scanning direction becomes smaller for printing media with smaller transport amounts.

2. The aforementioned transport unit is A drive roller that is driven to rotate, Each of the aforementioned plurality of printing media is provided with a plurality of nip rollers that nip the printing media between themselves and the drive roller to transport the printing media, The plurality of nip rollers can individually switch between a nip state, where the printing medium is nipped between them and the drive roller, and a nip release state, The inkjet printing apparatus according to claim 1, characterized in that the amount of each printing medium transported is adjusted by switching between a nip state and a nip release state at each nip roller.

3. The aforementioned transport unit is The system further includes a guide member that guides the plurality of printing media upstream of the drive roller in the transport direction of the printing media, The inkjet printing apparatus according to claim 2, characterized in that the nip roller in the nip-released state is positioned to press the printing medium against the guide member.

4. The inkjet printing apparatus according to claim 2 or 3, characterized in that the control unit stops the drive roller when switching any of the nip rollers from a nip state to a nip release state.

Images