JP2018171743A - Ink jet printer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an ink jet printer which can alleviate reduction in the printing quality.SOLUTION: An ink jet printer 3 includes: a plurality of ink jet heads which are arranged side by side in the conveyance direction of a web W and print an image by discharging ink to the conveyed web W; edge sensors 23, 24 which are arranged side by side in the conveyance direction of the web W and detect the position of the edge in the width direction of the web W respectively; a meander correction unit 22 which corrects the meander of the web W; and a printer control unit 26 which calculates the meander amount of the web W on the basis of the detection values by the edge sensors 23, 24 at the timing at which the conveyance times of the web W between the edge sensors 23, 24 are shifted from each other, and controls the meander correction unit 22 so as to correct the meander of the web W on the basis of the calculated meander amount. The distance on the conveyance path of the web W between the adjacent ink jet heads is the natural number multiple of the distance on the conveyance path of the web W between the edge sensors 23, 24.SELECTED DRAWING: Figure 1

Description

  The present invention relates to an inkjet printing apparatus that prints an image by discharging ink from an inkjet head onto a web.

  2. Related Art Inkjet printing apparatuses that print an image by ejecting ink from an inkjet head onto a web while conveying a long web as a print medium are known.

  In such an ink jet printing apparatus, if meandering in which the position in the width direction of the web is shifted occurs, the landing positions of the inks between the plurality of ink jet heads may be shifted, and the print image quality may be deteriorated.

  On the other hand, a meandering correction device that corrects meandering by adjusting the position of the web in the width direction by rotating the roller around which the web is wound so as to be inclined with respect to the width direction of the web is known. . When such a meandering correction device is used, the edge position of the web is detected by an edge sensor, and based on the detected value, the meandering correction device is controlled so as to return the edge to a normal position to correct the meandering of the web. .

  By the way, the edge of the web may have unevenness in the width direction due to a web processing error or the like. For this reason, even when the meandering of the web does not occur, the meandering may be erroneously detected by the edge sensor detecting the uneven portion of the edge of the web. When the meandering correction operation of the web by the meandering correction device is performed based on the meandering erroneously detected in this way, the print image quality is deteriorated.

  Here, Patent Document 1 discloses a technique for calculating the amount of meandering of the web based on the difference between the detected values of the edge of the web by each edge sensor at the timing shifted by the web conveyance time between the two edge sensors. Is disclosed. As a result, even if there is unevenness in the width direction at the edge due to a web processing error or the like, the influence is removed, and the web meandering is detected with high accuracy.

JP, 2006-87891, A

  However, the technique of Patent Document 1 cannot detect meandering having a period during which the web is transported between two edge sensors as one cycle, and meandering having a frequency that is a multiple of the meandering time. For this reason, even if the meandering correction is performed based on the meandering amount of the web detected by the technique of Patent Document 1, a meandering component that is not corrected remains, and there is a possibility that the print image quality is deteriorated.

  The present invention has been made in view of the above, and an object of the present invention is to provide an ink jet printing apparatus that can reduce a decrease in print image quality.

  In order to achieve the above object, a first feature of an ink jet printing apparatus according to the present invention is a plurality of ink jet heads that are arranged side by side in the web conveyance direction and print an image by ejecting ink onto the web being conveyed. , Two detection units arranged side by side in the conveyance direction, each detecting the position of the edge in the width direction of the web, a meandering correction unit correcting the meandering of the web, and the web conveyance between the two detection units A control unit that calculates the meandering amount of the web based on the detection values by the two detection units at timings shifted from each other, and controls the meandering correction unit to correct the meandering of the web based on the calculated meandering amount The distance on the web conveyance path between the adjacent inkjet heads is a distance on the web conveyance path between the two detection units. It lies in the fact of a natural number times.

  A second feature of the ink jet printing apparatus according to the present invention is that the ink jet head has a plurality of head modules arranged in a staggered manner along the width direction, and is arranged in a staggered manner and shifted in the transport direction. The distance on the web conveyance path between the head modules is a natural number multiple of the distance on the web conveyance path between the two detection units.

  According to the first feature of the ink jet printing apparatus according to the present invention, the control unit is configured to control the web based on the detection value by the two detection units at a timing when the web conveyance time between the two detection units is shifted from each other. The amount of meandering is calculated. Then, the control unit controls the meandering correction unit to correct the meandering of the web based on the calculated meandering amount. As a result, even if there is unevenness in the width direction at the edge of the web, the influence can be removed and the meandering of the web can be detected and corrected with high accuracy. Further, the distance on the web conveyance path between the adjacent inkjet heads is a natural number multiple of the distance on the web conveyance path between the two detection units. For this reason, even if the meandering of the web having a frequency that is a natural number multiple of meandering with one cycle of the web conveyance time between the two detection units occurs and the meandering correction cannot be performed, the ink landing positions between the respective inkjet heads Deviation is suppressed.

  Thus, according to the first feature of the ink jet printing apparatus according to the present invention, it is possible to detect and correct the web meandering with high accuracy, and even when the web meandering that cannot be corrected occurs, between the ink jet heads. Ink landing position deviation is suppressed. Accordingly, it is possible to reduce a decrease in print image quality.

  According to the second feature of the inkjet printing apparatus according to the present invention, the distance between the head modules arranged in the staggered arrangement in the web conveyance direction on the web conveyance path is the web between the two detection units. Is a natural number multiple of the distance on the transport path. For this reason, even when the meandering of the web having a frequency that is a natural number multiple of meandering, where the web conveyance time between the two detection units is one cycle, and the meandering correction cannot be performed, in the print image by the joint portion of the head module Generation of white and black lines is suppressed. Therefore, it is possible to further reduce the deterioration in print image quality.

1 is a schematic configuration diagram of a printing system including an inkjet printing apparatus according to an embodiment. It is a perspective view which shows the meandering correction | amendment part and edge sensor of the inkjet printing apparatus which concerns on embodiment. It is a top view of the inkjet head of the inkjet printing apparatus which concerns on embodiment. It is a top view of the inkjet head of the inkjet printing apparatus which concerns on embodiment. FIG. 2 is a control block diagram of the printing system shown in FIG. 1. It is a flowchart for demonstrating meandering correction | amendment control of a web. It is explanatory drawing of the amount of meandering of a web. It is description of the meandering of the web which is not detected in the inkjet printing apparatus which concerns on embodiment. Schematic representation of the movement of dots formed on a web between inkjet heads when the web has a meander frequency that is a multiple of the natural number of meanders with the web transport time between edge sensors as one cycle. FIG. When web meandering having a frequency that is a natural number multiple of meandering with the web conveyance time between edge sensors as one period occurs, between the head modules of dots formed on the web at the joint portion of the head module It is a figure which shows the mode of a movement typically.

  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.

  The following embodiments exemplify devices for embodying the technical idea of the present invention, and the technical idea of the present invention is the material, shape, structure, arrangement, etc. of each component. Is not specified as follows. The technical idea of the present invention can be variously modified within the scope of the claims.

  FIG. 1 is a schematic configuration diagram of a printing system including an inkjet printing apparatus according to an embodiment of the present invention. FIG. 2 is a perspective view showing a meandering correction unit and an edge sensor of the ink jet printing apparatus. FIG. 3 is a plan view of the ink jet head of the ink jet printing apparatus. FIG. 4 is a partially enlarged view of the inkjet head. FIG. 5 is a control block diagram of the printing system shown in FIG. In the following description, the direction orthogonal to the paper surface of FIG. 1 is the front-rear direction, and the front surface direction is the front. Also, the top, bottom, left, and right of the paper surface in FIG.

  As shown in FIGS. 1 and 5, the printing system 1 according to the present embodiment includes an unwinding device 2, an inkjet printing device 3, and a winding device 4.

  The unwinding device 2 unwinds the web W, which is a long print medium made of film, paper, or the like, to the inkjet printing device 3. The unwinding device 2 includes a web roll support shaft 11, a brake 12, and an unwinding device control unit 13.

  The web roll support shaft 11 rotatably supports the web roll 16. The web roll support shaft 11 is formed in a long shape extending in the front-rear direction. The web roll 16 is obtained by winding a web W in a roll shape.

  The brake 12 brakes the web roll support shaft 11. Thereby, a tension | tensile_strength is provided to the web W between the web roll 16 and the conveyance roller 42 of the inkjet printing apparatus 3 mentioned later.

  The unwinding device control unit 13 controls the brake 12. The unwinding device control unit 13 includes a CPU, a memory, a hard disk, and the like.

  The inkjet printing apparatus 3 prints an image on the web W while conveying the web W unwound from the unwinding apparatus 2. The ink jet printing apparatus 3 includes a transport unit 21, a meandering correction unit 22, edge sensors (detection units) 23 and 24, printing units 25 </ b> A and 25 </ b> B, and a printing device control unit (control unit) 26. In some cases, the alphabetic suffixes in the reference numerals of the printing units 25A and 25B are omitted and collectively described.

  The transport unit 21 transports the web W unwound from the unwinding device 2. The transport unit 21 includes guide rollers 31 to 40, 20 head lower support members 41, a pair of transport rollers 42, and a transport motor 43.

  The guide rollers 31 to 40 guide the web W conveyed in the inkjet printing apparatus 3. The guide rollers 31 to 40 are driven to rotate by the web W being conveyed. The guide rollers 31 to 40 are formed in a long shape extending in the front-rear direction. A guide path of the web W in the ink jet printing apparatus 3 is formed by the guide rollers 31 to 40, the head lower support member 41, the transport roller 42, and meander correction rollers 46 and 47 of the meander correction unit 22 described later.

  The guide rollers 31 and 32 guide the web W between the unwinding device 2 and the meandering correction unit 22. The guide roller 31 is disposed below the left end portion of the inkjet printing apparatus 3. The guide roller 32 is disposed between the guide roller 31 and a meandering correction roller 46 of the meandering correction unit 22 described later.

  The guide rollers 33 to 39 guide the web W between the meandering correction unit 22 and the conveyance roller 42. The guide roller 33 is disposed on the left side of a meandering correction roller 47 of the meandering correction unit 22 described later. The guide roller 34 is disposed above the guide roller 33. The guide roller 35 has the same height as the guide roller 34 and is disposed on the right side of the guide roller 34. The guide roller 36 is disposed below the guide roller 35 and at a position higher than the guide roller 33. The guide roller 37 is disposed on the left side of the guide roller 36, in the vicinity of the right side of the web W between the guide rollers 33 and 34, and at the same height as the guide roller 36. The guide roller 38 is disposed on the lower right side of the guide roller 37. The guide roller 39 is disposed slightly below the right side of the guide roller 38.

  The guide roller 40 guides the web W between the conveyance roller 42 and the winding device 4. The guide roller 40 is disposed at the lower part of the right end portion of the inkjet printing apparatus 3.

  The head lower support member 41 supports the web W under the head unit 51 described later between the guide rollers 34 and 35 and between the guide rollers 36 and 37. The head lower support member 41 is formed in a long shape extending in the front-rear direction. Ten head support members 41 are arranged between the guide rollers 34 and 35 and between the guide rollers 36 and 37, respectively. Two head lower support members 41 are arranged immediately below each head unit 51.

  The pair of transport rollers 42 transport the web W toward the winding device 4 while nipping the web W. The conveyance roller 42 is formed in a long cylindrical shape extending in the front-rear direction. The pair of transport rollers 42 is disposed between the guide rollers 39 and 40.

  The carry motor 43 drives the carry roller 42 to rotate.

  The meandering correction unit 22 corrects the meandering of the web W by moving the web W in the width direction (front-rear direction). The meandering correction unit 22 is disposed on the upstream side in the web W conveyance direction from the printing unit 25 on the web W conveyance path. Specifically, the meandering correction unit 22 is disposed between the guide rollers 32 and 33. As shown in FIGS. 1, 2, and 5, the meandering correction unit 22 includes meandering correction rollers 46 and 47, a meandering correction roller holding unit 48, and a meandering correction motor 49.

  The meandering correction rollers 46 and 47 are rollers for guiding the web W and correcting the meandering of the web W. The meandering correction rollers 46 and 47 are formed in a long cylindrical shape extending in the front-rear direction. The meandering correction rollers 46 and 47 are driven to rotate following the web W being conveyed. The meandering correction roller 46 is disposed on the right side of the guide roller 32. The meandering correction roller 47 is disposed above the meandering correction roller 46. The meandering correction rollers 46 and 47 correct the meandering by moving the web W in the width direction by rotating so as to be inclined with respect to the width direction (front-rear direction) of the web W when viewed from the left-right direction. is there. The amount of movement of the web W in the width direction is adjusted by the rotation angle of the meandering correction rollers 46 and 47.

  The meandering correction roller holding unit 48 holds the meandering correction rollers 46 and 47. The meandering correction roller holding portion 48 can be rotated around a rotation shaft 48a parallel to the left-right direction. Thereby, the meandering correction rollers 46 and 47 are rotatable so as to be inclined with respect to the width direction (front-rear direction) of the web W when viewed from the left-right direction.

  The meandering control motor 49 rotates the meandering correction roller holding portion 48 around the rotation shaft 48a.

  The edge sensors 23 and 24 detect the position of the edge in the width direction (front-rear direction) of the web W. In the present embodiment, the edge sensors 23 and 24 are arranged on the front side of the web W and detect the position of the front edge of the web W. The edge sensors 23 and 24 are arranged in the vicinity of the meandering correction roller 47 on the downstream side in the web W conveyance direction (left-right direction) at predetermined intervals.

  The printing units 25A and 25B print images on the front surface and the back surface of the web W, respectively. The printing unit 25 </ b> A is disposed in the vicinity of the upper portion of the web W between the guide rollers 34 and 35. The printing unit 25 </ b> B is disposed near the upper portion of the web W between the guide rollers 36 and 37. Each of the printing units 25A and 25B includes five head units 51.

  The head unit 51 has an inkjet head 56. The inkjet head 56 prints an image by ejecting ink onto the web W. In the printing unit 25, the five inkjet heads 56 eject inks of different colors. Each inkjet head 56 has a plurality of head modules 57. In the present embodiment, as shown in FIG. 3, each inkjet head 56 has 10 head modules 57.

  As shown in FIG. 4, the head module 57 includes a plurality of nozzles 58 that discharge ink and open in a nozzle surface 57 a that faces the web W. The nozzles 58 are arranged at a predetermined pitch P along the main scanning direction (front-rear direction) that is the width direction of the web W.

  In the inkjet head 56, the ten head modules 57 are staggered along the main scanning direction. Specifically, the ten head modules 57 are arranged in the main scanning direction (front-rear direction), and every other position is shifted in the sub-scanning direction (left-right direction) which is the web W conveyance direction. Has been placed. In other words, the ten head modules 57 each include five head modules 57 arranged at predetermined intervals in the main scanning direction, and form head module rows 59A and 59B that are separated from each other in the sub scanning direction. . The head module rows 59A and 59B are arranged so as to be shifted from each other by half the interval of the head modules 57 in the head module row 59 in the main scanning direction.

  Further, each head module 57 is arranged so that the head modules 57 adjacent in the main scanning direction partially overlap in the main scanning direction. That is, in the inkjet head 56, there is a joint portion E between the head modules 57 adjacent in the main scanning direction, where the head modules 57 overlap in the main scanning direction.

  In each head module 57, one head module 57 sharing the joint portion E and the other head module 57 are arranged such that the positions of the respective nozzles 58 in the main scanning direction coincide with each other.

  Here, in the printing unit 25, each inkjet head 56 is arranged such that the head distance Y1 is n times the edge sensor distance L (n is a natural number). The head-to-head distance Y1 is a distance on the web conveyance path between the adjacent inkjet heads 56. More specifically, the head-to-head distance Y1 is a distance on the web conveyance path between the nozzles 58 of the head module row 59A or the nozzles 58 of the head module row 59B in the adjacent inkjet head 56. The distance L between the edge sensors is a distance on the conveyance path of the web W between the edge sensors 23 and 24.

  In the inkjet head 56, the head module distance Y2 is m times the edge sensor distance L (m is a natural number). The inter-head module distance Y2 is a distance on the conveyance path of the web W between the head modules 57 arranged in a staggered arrangement and shifted in the sub-scanning direction. More specifically, the distance Y2 between the head modules is on the transport path of the web W between the nozzles 58 of the head module 57 of the head module row 59A and the head module 57 of the head module row 59B in the same inkjet head. The distance at.

  The printing device control unit 26 controls the operation of each unit of the inkjet printing device 3. The printing apparatus control unit 26 includes a CPU, a RAM, a ROM, a hard disk, and the like.

  When performing printing, the printing apparatus control unit 26 drives the inkjet head 56 of the printing units 25 </ b> A and 25 </ b> B to print an image on the web W while rotating the conveyance roller 42 by the conveyance motor 43 to convey the web W. Let

  Further, the printing device control unit 26 performs meandering correction control of the web W during the printing operation. Specifically, during the printing operation, the printing apparatus control unit 26 determines the web W based on the detection values of the edge sensors 23 and 24 at the timing when the conveyance time of the web W between the edge sensors 23 and 24 is shifted from each other. The amount of meandering is calculated. Then, the printing apparatus control unit 26 controls the meandering correction unit 22 to correct the meandering of the web W based on the calculated meandering amount.

  The winding device 4 winds the web W printed by the inkjet printing device 3. The winding device 4 includes a winding shaft 61, a winding motor 62, and a winding device control unit 63.

  The winding shaft 61 winds and holds the web W. The winding shaft 61 is formed in a long shape extending in the front-rear direction.

  The winding motor 62 rotates the winding shaft 61 in the clockwise direction in FIG. The web W is wound around the winding shaft 61 by the rotation of the winding shaft 61.

  The winding device control unit 63 controls driving of the winding motor 62. The winding device control unit 63 includes a CPU, a memory, a hard disk, and the like.

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

  When printing is performed by the printing system 1, when a print job is input, the printing apparatus control unit 26 starts driving the conveyance motor 43, and the winding apparatus control unit 63 starts driving the winding motor 62. Thereby, the conveyance of the web W is started from the unwinding device 2 toward the winding device 4. When the conveyance speed of the web W reaches a predetermined printing conveyance speed Vg after the conveyance of the web W is started, the unwinding device control unit 13 starts driving the brake 12. When the web roll support shaft 11 is braked by the brake 12, the web W is conveyed while tension is applied to the web W between the web roll 16 and the conveyance roller 42. Further, after the conveyance speed of the web W reaches the printing conveyance speed Vg, the printing apparatus control unit 26 controls the conveyance motor 43 so as to maintain the printing conveyance speed Vg.

  After starting the constant speed conveyance at the print conveyance speed Vg of the web W, the printing apparatus control unit 26 controls the inkjet heads 56 of the printing units 25A and 25B to print an image on the web W based on the print job.

  Here, in the joint portion E of the inkjet head 56, the nozzle 58 used for image printing is between the nozzle 58 of one head module 57 and the nozzle 58 of the other head module 57 in the middle of the joint portion E. Can be switched. For example, in the example of FIG. 4 in which there are eight nozzles 58 in the joint portion E, four nozzles 58 on the front side of the joint portion E are used in the front head module 57, and after the joint portion E in the rear head module 57. Four nozzles 58 on the side are used. Thus, dots are formed at the pitch P of the nozzles 58 even at the joint portion E.

  Further, the printing apparatus control unit 26 starts the meandering correction control of the web W after starting the constant speed conveyance at the printing conveyance speed Vg of the web W and before starting the printing by the inkjet head 56.

  This meandering correction control will be described with reference to the flowchart of FIG. The meandering correction control of the web W is started after L / Vg, which is the conveyance time of the web W between the edge sensors 23 and 24, has elapsed after the start of constant-speed conveyance at the printing conveyance speed Vg of the web W. Here, the printing apparatus control unit 26 acquires the detected value of the position of the edge of the web W from the edge sensors 23 and 24 in a predetermined cycle before the start of the meandering correction control of the web W.

  When the meandering correction control is started and the detection value is acquired from the downstream edge sensor 23 in step S1 of FIG. 6, in step S2, the printing apparatus control unit 26 meanders in the acquisition period of the detection value of the current edge position. The quantity δX (t) is calculated. The meandering amount δX (t) is calculated by the following equation (1).

δX (t) = S1 (t) −S2 (t−L / Vg) (1)
Here, S1 (t) is a detection value of the downstream edge sensor 23 acquired in the acquisition period of the detection value of the current edge position. Further, S2 (t−L / Vg) is a detection value of the upstream edge sensor 24 in a period including a timing L / Vg earlier than the acquisition timing of the detection value of the edge position in the current period. .

  That is, S1 (t) and S2 (t−L / Vg) are detected values by the edge sensors 23 and 24 at the timing when the web W conveyance time (L / Vg) between the edge sensors 23 and 24 is shifted from each other. It corresponds to.

  S1 (t) and S2 (t−L / Vg) are values obtained by the edge sensors 23 and 24 respectively detecting the position in the width direction of the same portion in the conveyance direction of the web W. For this reason, for example, as shown in FIG. 7, when the edge portion of the web W has an uneven portion Wa, and the detection value S1 (t) of the edge sensor 23 detects a part of the uneven portion Wa, the edge The detection value S2 (t−L / Vg) of the sensor 24 is also the same portion detected. Thereby, even if the edge portion of the web W has the uneven portion Wa, the meandering amount δX (t) from which the influence of the uneven portion Wa is removed can be calculated.

  Since the meandering amount δX (t) is calculated using the detection values S1 (t) and S2 (t−L / Vg) as described above, the meandering correction control is performed as described above. After the start of constant-speed conveyance at the speed Vg, the operation starts after L / Vg has elapsed.

  Returning to FIG. 6, in step S <b> 3, the printing apparatus control unit 26 controls the meandering correction unit 22 to cancel the meandering of the web W based on the meandering amount δX (t) calculated in step S <b> 2. Specifically, the printing apparatus control unit 26 controls the meandering correction motor 49 to rotate the meandering correction rollers 46 and 47 so that the meandering amount δX (t) becomes zero.

  Next, in step S4, the printing apparatus control unit 26 determines whether printing based on the print job is finished. If it is determined that printing has not ended (step S4: NO), the printing apparatus control unit 26 returns to step S1, acquires the detection value of the next cycle from the downstream edge sensor 23, and performs the subsequent processing. repeat.

  When it is determined that the printing is finished (step S4: YES), the printing apparatus control unit 26 finishes the meandering correction control.

  By the way, as shown in FIG. 8, when the meandering of the web W has L / Vg as one cycle, the meandering amount δX (t) calculated by the equation (1) becomes zero. In such meandering, even if the web W is meandering, the position of the edge sensor 23 and the position of the edge sensor 24 in the conveyance direction of the web W are the same in the width direction of the web W. . The same applies to meandering having a frequency that is a multiple of meandering with L / Vg as one cycle.

  That is, in the inkjet printing apparatus 3, when the meandering of the web W having a frequency that is a natural number multiple of meandering with L / Vg as one cycle is generated, the meandering is not detected, and the meandering is not corrected.

  On the other hand, as described above, in the inkjet printing apparatus 3, the distance Y1 between the heads is a natural number times the distance L between the edge sensors.

  Here, the state of movement of the dots formed on the web W between the inkjet heads 56 when the meandering of the web W having a frequency that is a natural number multiple of the meandering with L / Vg as one cycle occurs. This is schematically shown in FIG. In the example of FIG. 9, the meandering of the web W has L / Vg as one cycle, and Y1 = 4L. In the example of FIG. 9, the movement of dots between two adjacent inkjet heads 56 is shown.

  In FIG. 9, dots 71 are formed by the upstream inkjet head 56. When the dot 71 reaches a position where the downstream inkjet head 56 overlaps the dot 71 in the sub-scanning direction, the position of the dot 71 in the main scanning direction is the position when formed by the inkjet head 56. Have returned to. For this reason, the landing position deviation of the ink between the two inkjet heads 56 is suppressed.

  In the example of FIG. 9, the case where the meandering of the web W has one cycle of L / Vg is shown, but the same applies to the case of meandering having multiple times the frequency of meandering with one cycle of L / Vg. It is. In the example of FIG. 9, the two adjacent inkjet heads 56 are shown, but similarly, the landing position deviation of the ink can be suppressed between any inkjet heads. The same applies to the case where Y1 is a natural number multiple other than four times L.

  Therefore, in the inkjet printing apparatus 3, meandering having a frequency that is a natural number multiple of meandering with L / Vg as one cycle occurs in the web W, and even when the meandering correction is not performed, the printing unit 25 has a gap between the inkjet heads 56. Ink landing position deviation is suppressed.

  Further, as described above, in the inkjet printing apparatus 3, the head module distance Y2 is a natural number times the edge sensor distance L.

  Here, when the meandering of the web W having a frequency that is a natural number multiple of meandering with one cycle of L / Vg occurs, the movement between the head modules 57 of the dots formed on the web W at the joint portion E This is schematically shown in FIG. In the example of FIG. 10, the meandering of the web W has L / Vg as one cycle, and Y2 = L.

  In FIG. 10, a dot 72 is formed by the front head module 57 of the two head modules 57 sharing the joint portion E. When the dot 72 reaches the position of the nozzle 58 of the rear head module 57 in the sub-scanning direction, the position of the dot 72 in the main scanning direction returns to the position when formed by the inkjet head 56.

  For this reason, in the main scanning direction, the distance between the rearmost dot 72 and the frontmost dot 73 formed by the rear head module 57 is the same as the pitch P of the nozzles 58. Dots 73 are formed. As a result, in the image formed by the joint portion E, the occurrence of white stripes due to wide dot intervals and black stripes due to narrow dot intervals can be suppressed.

  In the example of FIG. 10, the case where the meandering of the web W has one cycle of L / Vg is shown, but the same applies to the case of meandering having multiple times the frequency of meandering with one cycle of L / Vg. It is. The same applies to the case where Y2 is a multiple of L.

  Therefore, in the ink jet printing apparatus 3, meandering having a frequency that is a natural number multiple of meandering with L / Vg as one cycle occurs in the web W, and even when the meandering correction is not performed, in the print image by the joint portion E of the head module 57. Generation of white and black lines is suppressed.

  After the printing based on the print job is completed, the unwinding device control unit 13 stops the brake 12, the printing device control unit 26 stops the conveyance motor 43, and the winding device control unit 63 stops the winding motor 62. . Thereby, conveyance of a web is complete | finished and a series of operation | movement is complete | finished.

  As described above, in the inkjet printing apparatus 3, the printing apparatus control unit 26 detects the edge sensors 23 and 24 at the timing when the web W conveyance time (L / Vg) between the edge sensors 23 and 24 is shifted from each other. Based on the value, the amount of meandering of the web W is calculated. Then, the printing apparatus control unit 26 controls the meandering correction unit 22 to correct the meandering of the web W based on the calculated meandering amount. Thereby, even when the edge of the web W has unevenness in the width direction, the influence can be removed, and the meandering of the web W can be detected and corrected with high accuracy.

  In the inkjet printing apparatus 3, the head distance Y1 is a natural number times the edge sensor distance L. For this reason, even if the meandering of the web W having a frequency that is a natural number times the meandering of the meandering of the web W between the edge sensors 23 and 24 (L / Vg) occurs and the meandering correction cannot be performed, each ink jet Ink landing position deviation between the heads 56 is suppressed.

  As described above, the ink jet printing apparatus 3 can detect and correct the meandering of the web W with high accuracy, and suppress the deviation of the landing positions of the inks between the ink jet heads 56 even when the meandering of the web W cannot be corrected. It is done. Therefore, according to the inkjet printing apparatus 3, it is possible to reduce a decrease in print image quality.

  Further, in the inkjet printing apparatus 3, the distance Y2 between the head modules is a natural number times the distance L between the edge sensors. For this reason, even if the meandering of the web W having a frequency that is a natural number multiple of meandering with the conveyance time (L / Vg) of the web W between the edge sensors 23 and 24 as one cycle occurs and the meandering cannot be corrected, the joint portion The occurrence of white and black lines in the printed image due to E is suppressed. Therefore, it is possible to further reduce the deterioration in print image quality.

  In the above-described embodiment, the configuration in which the inkjet head 56 includes the plurality of head modules 57 has been described. However, the inkjet head may be a single unit that covers the entire width of the web W.

  In the above-described embodiment, the configuration in which the unwinding device and the winding device are connected to the inkjet printing apparatus as separate devices has been described, but the configuration in which the unwinding unit and the winding unit are incorporated in the inkjet printing apparatus is also possible. Good.

  The present invention is not limited to the above-described embodiments as they are, and can be embodied by modifying the components without departing from the scope of the invention in the implementation stage. Various inventions can be formed by appropriately combining a plurality of constituent elements disclosed in the embodiments. For example, some components may be deleted from all the components shown in the embodiment.

DESCRIPTION OF SYMBOLS 1 Printing system 2 Unwinding device 3 Inkjet printing device 4 Winding device 21 Conveyance part 22 Meandering part 23, 24 Edge sensor 25, 25A, 25B Printing part 26 Printing apparatus control part 51 Head unit 56 Inkjet head 57 Head module 58 Nozzle E Joint part W Web

Claims (2)

A plurality of inkjet heads arranged side by side in the web conveyance direction and ejecting ink onto the web to be conveyed to print an image;
Two detectors arranged side by side in the transport direction, each detecting the position of an edge in the width direction of the web;
A meandering correction unit for correcting the meandering of the web;
The web meandering amount is calculated based on the detection value by the two detecting units at the timing when the web conveyance time between the two detecting units is shifted from each other, and the web meandering is corrected based on the calculated meandering amount. And a control unit for controlling the meandering correction unit,
An ink jet printing apparatus, wherein a distance on the web conveyance path between the adjacent inkjet heads is a natural number multiple of a distance on the web conveyance path between the two detection units. The inkjet head has a plurality of head modules arranged in a staggered manner along the width direction,
In the staggered arrangement, a distance on the web conveyance path between the head modules arranged in the conveyance direction is a natural number multiple of a distance on the web conveyance path between the two detection units. The inkjet printing apparatus according to claim 1.