JP2019147360A - Printing device - Google Patents

Abstract

To provide a printing device that can suppress deterioration in printing quality while being suppressed from being complicatedly structured.SOLUTION: An encoder 22A outputs a pulse signal according to a rotation angle of a guide roller 34 that rotates in synchronization with a web W to be carried. An encoder 22B outputs a pulse signal according to a rotation angle of a guide roller 36 that rotates in synchronization with a web W to be carried. A printing device control unit 24 controls timing for discharging ink in each inkjet head of a printing unit 23A on the basis of an output pulse signal by the encoder 22A after timing when carrying of the web W is started. Further, the printing device control unit 24 controls timing for discharging ink in each inkjet head of a printing unit 23B on the basis of an output pulse signal by the encoder 22B after timing when the carrying of the web W is started.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a printing apparatus for printing on a web.

  2. Description of the Related Art There is known a printing apparatus that prints an image by ejecting ink from an inkjet head onto a web while conveying a long web as a printing medium.

  Moreover, as such a printing apparatus, a printing unit for the front surface of the web and a printing unit for the back surface arranged on the downstream side of the printing unit for the front surface in the web conveying direction can be printed on both sides of the web. (See Patent Document 1).

  In addition, as a printing apparatus capable of double-sided printing as described above, there are printers in which the front-side printing unit and the back-side printing unit each have a plurality of inkjet heads that eject inks of different colors. Here, the plurality of inkjet heads in each printing unit are arranged in parallel in the web conveyance direction.

  In such a printing apparatus, the ink ejection timing in each inkjet head is controlled based on the output pulse signal of an encoder connected to a roller that rotates in synchronization with the conveyed web.

JP 2003-63072 A

  In the ejection timing control as described above, the accuracy of the ink landing position decreases as the inkjet head is farther from the encoder due to the effect of web expansion and contraction. For this reason, for example, when the encoder is disposed in the vicinity of the upstream side of the printing unit for the front surface, the deviation of the ink landing position between the inkjet heads due to the decrease in the ink landing accuracy in the printing unit for the back surface far from the encoder. May occur. That is, there is a possibility that color misregistration occurs in the printed image on the back surface and the print image quality is deteriorated.

  On the other hand, there is known a printing apparatus that arranges encoders in the vicinity of the front surface printing unit and the back surface printing unit, and uses these encoders to control the ejection timing of ink in each printing unit. Yes.

  In such a printing apparatus, a mark serving as a mark is placed on the web, and the mark is detected by sensors arranged in the vicinity of the upstream side of the front surface printing unit and the back surface printing unit. The ink ejection timing of each inkjet head is determined based on the output pulse signal of the corresponding encoder with respect to the timing at which the corresponding sensor detects the mark for the front surface printing unit and the back surface printing unit. To control.

  In this way, by controlling the ink discharge timing using the encoders corresponding to the front surface printing unit and the back surface printing unit, printing based on the deviation of the ink landing position between the ink jet heads as described above. Reduction in image quality is suppressed.

  However, with the above-described technology for controlling the ink ejection timing of the front surface printing unit and the back surface printing unit using the encoders corresponding to the timing at which the sensor detects the mark, the mark It is necessary to provide a mechanism for hitting the mark and a sensor for detecting the mark. This leads to complication of the device configuration.

  The present invention has been made in view of the above, and an object of the present invention is to provide a printing apparatus capable of reducing deterioration in print image quality while suppressing the complexity of the apparatus configuration.

  In order to achieve the above object, a printing apparatus of the present invention has a plurality of printing mechanisms arranged in parallel in the web conveyance direction, and prints an image on each first printing mechanism on the first surface of the web to be conveyed. And a plurality of printing mechanisms that are arranged on the downstream side of the first printing unit in the conveying direction and arranged in parallel with the conveying direction, and are provided on the second surface of the web to be conveyed A second printing unit that prints an image by each of the printing mechanisms; at least one first roller that is arranged upstream of the second printing unit and that rotates in synchronization with a conveyed web; and the first printing unit Installed and installed on the first roller different from the at least one second roller that is disposed on the downstream side of the first roller that is further downstream and the most downstream and rotates in synchronization with the conveyed web. Rotation of the first roller At least one first encoder that outputs a pulse signal according to the degree and at least one second encoder that is installed on each of the different second rollers and outputs a pulse signal according to the rotation angle of the installed second roller. Based on the output pulse signal of the encoder and at least one first encoder from the control start timing, the printing timing in each printing mechanism of the first printing unit is controlled, and at least one second from the control start timing. And a control unit that controls printing timing in each of the printing mechanisms of the second printing unit based on an output pulse signal of the encoder.

  According to the printing apparatus of the present invention, it is possible to reduce deterioration in print image quality while suppressing the complexity of the apparatus configuration.

1 is a schematic configuration diagram of a printing system including a printing apparatus according to an embodiment. FIG. 2 is a control block diagram of the printing system shown in FIG. 1. FIG. 2 is a block diagram illustrating a configuration of a printing apparatus control unit included in the printing apparatus of the printing system illustrated in FIG. 1. It is explanatory drawing of the holding angle of the web with respect to a guide roller. It is explanatory drawing of ink discharge timing control.

  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 a printing apparatus according to an embodiment of the present invention. FIG. 2 is a control block diagram of the printing system shown in FIG. FIG. 3 is a block diagram illustrating a configuration of a printing apparatus control unit included in the printing apparatus of the printing system illustrated in FIG. 1. In the following description, the direction orthogonal to the paper surface of FIG. Also, the top, bottom, left, and right of the paper surface in FIG.

  As shown in FIGS. 1 and 2, the printing system 1 according to the present embodiment includes an unwinding device 2, a 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 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 16 is obtained by winding a web W in a roll shape.

  The brake 12 brakes the web roll support shaft 11. Thereby, tension | tensile_strength is provided to the web W between the web roll 16 and the conveyance roller 43 of the 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 printing apparatus 3 prints an image on the web W while conveying the web W unwound from the web roll 16. The printing apparatus 3 includes a transport unit 21, an encoder 22A (first encoder), an encoder 22B (second encoder), a printing unit 23A (first printing unit), a printing unit 23B (second printing unit), And a printing apparatus control unit (control unit) 24. In some cases, alphabetic suffixes in the codes of the encoders 22A, 22B, etc. are omitted and are generally described.

  The transport unit 21 transports the web W unwound from the web roll 16 toward the winding device 4. The transport unit 21 includes guide rollers 31 to 40, 20 head lower rollers 41, a meandering control unit 42, a pair of transport rollers 43, and a transport motor 44.

  The guide rollers 31 to 40 guide the web W conveyed in the printing apparatus 3. The guide rollers 31 to 40 are driven to rotate by the web W being conveyed. A guide path of the web W in the transport unit 21 is formed by the guide rollers 31 to 40, the head lower roller 41, the transport roller 43, and meander control rollers 46 and 47 of the meander control unit 42 described later.

  The guide rollers 31 and 32 guide the web W between the unwinding device 2 and the meandering control unit 42. The guide roller 31 is disposed at the lower left end of the printing apparatus 3. The guide roller 32 is disposed between the guide roller 31 and a meandering control roller 46 of a meandering control unit 42 described later.

  The guide rollers 33 to 39 guide the web W between the meandering control unit 42 and the conveying roller 43. The guide roller 33 is disposed slightly above the left side of the meandering control roller 47 of the meandering control unit 42 described later. The guide roller 34 is disposed above the guide roller 33. The guide roller 35 is substantially 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 43 and the winding device 4. The guide roller 40 is disposed at the lower right end of the printing apparatus 3.

  The head lower roller 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. Ten head lower rollers 41 are arranged between the guide rollers 34 and 35 and between the guide rollers 36 and 37, respectively. Two head lower rollers 41 are arranged immediately below each head unit 51. The head lower roller 41 rotates following the web W being conveyed.

  The meandering control unit 42 corrects meandering that is a change in position in the width direction (front-rear direction) orthogonal to the conveyance direction of the web W. The meandering control unit 42 includes meandering control rollers 46 and 47 and a meandering control motor 48.

  The meandering control rollers 46 and 47 are rollers for guiding the web W and correcting the meandering of the web W. The meandering control rollers 46 and 47 are driven to rotate by the web W being conveyed. The meandering control rollers 46 and 47 are rotated so as to be inclined with respect to the width direction of the web W when viewed from the left and right directions, thereby moving the web W in the width direction and correcting meandering. The meandering control roller 46 is disposed on the right side of the guide roller 32. The meandering control roller 47 is disposed above the meandering control roller 46.

  The meandering control motor 48 rotates the meandering control rollers 46 and 47 about a rotation axis parallel to the left-right direction.

  The pair of transport rollers 43 transport the web W toward the winding device 4 while nipping the web W. The pair of transport rollers 43 are disposed between the guide rollers 39 and 40.

  The transport motor 44 drives the transport roller 43 to rotate.

  The encoder 22A is installed on the guide roller 34 (first roller), and outputs a pulse signal according to the rotation angle of the guide roller 34 that is driven to rotate (synchronously rotates) with the web W being conveyed. The encoder 22B is installed on the guide roller 36 (second roller), and outputs a pulse signal in accordance with the rotation angle of the guide roller 36 that rotates (synchronously rotates) following the web W being conveyed.

  Here, the guide rollers 34 and 36 on which the encoders 22A and 22B are respectively installed are folding rollers provided at positions where the web W is bent in the vicinity of the upstream side of the printing units 23A and 23B in the conveyance direction of the web W, respectively. ing.

  The folding roller is a roller in which the holding angle of the web W is equal to or larger than a specified angle. The specified angle of the holding angle is an angle set as the size of the holding angle at which the slippage of the web W with respect to the roller is suppressed. The holding angle of the web W in the roller is an angle at which the web W is wound around the roller. For example, the holding angle of the web W with respect to the guide roller 34 is θ shown in FIG.

  The printing unit 23A prints an image on the front surface (first surface) of the web W. The printing unit 23 </ 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 23A includes head units 51K, 51C, 51M, 51Y, and 51P.

  The head units 51K, 51C, 51M, 51Y, and 51P have inkjet heads (printing mechanisms) 56K, 56C, 56M, 56Y, and 56P, respectively. The head units 51K, 51C, 51M, 51Y, and 51P are arranged in parallel in the web W conveyance direction (left-right direction). For this reason, the inkjet heads 56K, 56C, 56M, 56Y, and 56P are also arranged in parallel in the conveyance direction of the web W.

  The inkjet heads 56K, 56C, 56M, 56Y, and 56P print images by ejecting black (K), cyan (C), magenta (M), yellow (Y), and preliminary ink colors onto the web W, respectively. . Red, light cyan or the like is used as the preliminary ink color.

  The inkjet head 56 has a plurality of nozzles (not shown) that are opened in the ink ejection surface facing the web W and are arranged along the main scanning direction (front-rear direction), and ejects ink from the nozzles.

  The printing unit 23B prints an image on the back surface (second surface) of the web W. The printing unit 23 </ b> B is disposed in the vicinity of the upper portion of the web W between the guide rollers 36 and 37. That is, the printing unit 23B is disposed on the downstream side of the printing unit 23A in the web W conveyance direction. The printing unit 23B includes head units 51K, 51C, 51M, 51Y, and 51P, similarly to the printing unit 23A.

  The printing unit 23B has a configuration in which the printing unit 23A is reversed left and right. The printing unit 23B has the same configuration as the printing unit 23A except that the printing unit 23B is reversed left and right.

  The printing device control unit 24 controls the operation of each unit of the printing device 3. As illustrated in FIG. 3, the printing apparatus control unit 24 includes a main control unit 61 and a conveyance control unit 62.

  The main control unit 61 controls the entire printing apparatus 3. The main controller 61 includes print controllers 66Ak, 66Ac, 66Am, 66Ay, 66Ap, 66Bk, 66Bc, 66Bm, 66By, and 66Bp. The print controllers 66Ak, 66Ac, 66Am, 66Ay, 66Ap, 66Bk, 66Bc, 66Bm, 66By, and 66Bp are each configured with a CPU, a memory, a hard disk, and the like.

  The print control units 66Ak, 66Ac, 66Am, 66Ay, and 66Ap control the driving of the inkjet heads 56K, 56C, 56M, 56Y, and 56P of the print unit 23A, respectively. The printing control units 66Ak, 66Ac, 66Am, 66Ay, 66Ap are respectively based on the output pulse signal of the encoder 22A from the web W conveyance start timing (control start timing), and the inkjet heads 56K, 56C, 56M, 56Y of the printing unit 23A, respectively. , 56P, the ink ejection timing (printing timing) is controlled.

  The print control units 66Bk, 66Bc, 66Bm, 66By, and 66Bp control the driving of the inkjet heads 56K, 56C, 56M, 56Y, and 56P of the printing unit 23B, respectively. The print control units 66Bk, 66Bc, 66Bm, 66By, 66Bp are based on the output pulse signals of the encoder 22B from the web W conveyance start timing, and the inks in the inkjet heads 56K, 56C, 56M, 56Y, 56P of the printing unit 23B, respectively. Control the discharge timing.

  The conveyance control unit 62 controls the conveyance of the web W by the conveyance unit 21. The conveyance control unit 62 includes a CPU, a memory, and the like.

  The winding device 4 winds the web W printed by the printing device 3. The winding device 4 includes a winding shaft 71, a winding motor 72, and a winding device control unit 73.

  The winding shaft 71 winds and holds the web W.

  The winding motor 72 rotates the winding shaft 71 in the clockwise direction in FIG. The web W is wound around the winding shaft 71 by the rotation of the winding shaft 71.

  The winding device control unit 73 controls driving of the winding motor 72. The winding device control unit 73 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, compressed image data to be printed by the inkjet head 56 controlled by each printing control unit 66 of the printing device control unit 24 is input from an external device. For example, compressed image data for printing with black ink on the surface of the web W by the inkjet head 56K of the printing unit 23A is input to the printing control unit 66Ak.

  When the compressed image data is input, each print control unit 66 performs a process of expanding the compressed image data.

  Further, the print control unit 66Ak instructs the conveyance control unit 62, the unwinding device control unit 13, and the winding device control unit 73 to start the conveyance of the web W, and starts the conveyance of the web W to the other printing control unit 66. To be notified.

  When the start of conveyance of the web W is instructed, the unwinding device control unit 13 causes the brake 12 to start outputting the braking force. Further, the conveyance control unit 62 of the printing apparatus control unit 24 causes the conveyance motor 44 to start driving the conveyance roller 43. Further, the winding device control unit 73 causes the winding motor 72 to start driving the winding shaft 71. Thereby, the unwinding and conveyance of the web W from the web roll 16 are started. 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 43.

  When the conveyance of the web W is started, the encoders 22A and 22B start outputting pulse signals in accordance with the rotation of the guide rollers 34 and 36, respectively. The output pulse signal of the encoder 22A is input to the print control units 66Ak, 66Ac, 66Am, 66Ay, 66Ap. The output pulse signal of the encoder 22B is input to the print control units 66Bk, 66Bc, 66Bm, 66By, and 66Bp.

  The print controllers 66Ak, 66Ac, 66Am, 66Ay, and 66Ap perform ink ejection timing control in the inkjet heads 56K, 56C, 56M, 56Y, and 56P of the printer 23A, respectively, based on the output pulse signal of the encoder 22A. The print controllers 66Bk, 66Bc, 66Bm, 66By, and 66Bp perform ink ejection timing control in the inkjet heads 56K, 56C, 56M, 56Y, and 56P of the printing unit 23B, respectively, based on the output pulse signal of the encoder 22B.

  Specifically, the printing control units 66Ak, 66Ac, 66Am, 66Ay, 66Ap start counting the number of output pulses of the encoder 22A when the input of the pulse signal from the encoder 22A is started. Further, when the input of the pulse signal from the encoder 22B is started, the print control units 66Bk, 66Bc, 66Bm, 66By, and 66Bp start counting the number of output pulses of the encoder 22B.

  When the count value of the number of output pulses of the encoder 22 reaches the print start count value set for each of the print control units 66, ink ejection based on image data by the corresponding inkjet head 56 is started. Let

  Specifically, for example, as shown in the upper part of FIG. 5, the print control unit 66Ak sets the count value of the number of output pulses of the encoder 22A from the web W conveyance start timing to the print control unit 66Ak. When the print start count value is reached, printing by the inkjet head 56K of the printing unit 23A is started. That is, the print control unit 66Ak causes the inkjet head 56K of the printing unit 23A to start ejecting ink based on image data for printing with the black ink on the surface of the web W. The print control unit 66Ak controls the ink ejection timing based on the image data by the inkjet head 56K of the printing unit 23A based on the output pulse signal of the encoder 22A, and causes each page to be printed.

  Here, when the conveyance of the web W is started, the web W is accelerated at a predetermined acceleration until the conveyance speed reaches a predetermined printing conveyance speed. When the transport speed of the web W reaches the print transport speed, the web W is then transported at a constant speed at the print transport speed. Printing on the web W is performed after the start of constant speed conveyance at the print conveyance speed of the web W.

  Therefore, the print start count value corresponding to the print control unit 66Ak is set so that printing by the inkjet head 56K is started after the constant speed conveyance of the web W is started. Until the count value of the number of output pulses of the encoder 22A reaches the print start count value corresponding to the print control unit 66Ak, it is a print start waiting period in the inkjet head 56K.

  Also, the print control units 66Ac, 66Am, 66Ay, and 66Ap also start printing, in which the count value of the number of output pulses of the encoder 22A from the web W conveyance start timing is set for each, similarly to the print control unit 66Ak. When the count value is reached, printing by the inkjet heads 56C, 56M, 56Y, and 56P of the printing unit 23A is started. The print control units 66Ac, 66Am, 66Ay, and 66Ap control the ink ejection timing based on the image data by the inkjet heads 56C, 56M, 56Y, and 56P of the print unit 23A based on the output pulse signal of the encoder 22A. Execute printing.

  Here, the print start count value corresponding to the print control unit 66Ac is equal to the distance between the inkjet heads 56K and 56C of the print unit 23A (the distance on the transport path) than the print start count value corresponding to the print control unit 66Ak. Only getting bigger. Similarly, the print start count values corresponding to the print controllers 66Am, 66Ay, and 66Ap are increased by the distance between the inkjet heads 56C and 56M, between the inkjet heads 56M and 56Y, and between the inkjet heads 56Y and 56P, respectively. Is set to As a result, ink of each color can be laid on the same pixel.

  Further, for example, as shown in the lower part of FIG. 5, the print control unit 66Bk starts the printing in which the count value of the number of output pulses of the encoder 22B from the web W conveyance start timing is set for the print control unit 66Bk. When the count value is reached, printing by the inkjet head 56K of the printing unit 23B is started. That is, the print control unit 66Bk causes the inkjet head 56K of the printing unit 23B to start ejecting ink based on image data for printing with the black ink on the back surface of the web W. The print control unit 66Bk controls the ink ejection timing based on the image data by the inkjet head 56K of the printing unit 23B based on the output pulse signal of the encoder 22B, and causes each page to be printed.

  The print start count value corresponding to the print control unit 66Bk is smaller than the print start count value corresponding to the print control unit 66Ap (the transport path) between the inkjet head 56P of the print unit 23A and the inkjet head 56K of the print unit 23B. It is larger by the distance above. In other words, the print start count value corresponding to the print control unit 66Bk is more between the inkjet head 56K of the print unit 23A and the inkjet head 56K of the print unit 23B than the print start count value corresponding to the print control unit 66Ak. It is larger by the distance.

  In addition, the print control units 66Bc, 66Bm, 66By, and 66Bp also start printing in which the count value of the number of output pulses of the encoder 22B from the web W conveyance start timing is set for each, similarly to the print control unit 66Bk. When the count value is reached, printing by the inkjet heads 56C, 56M, 56Y, and 56P of the printing unit 23B is started. The print control units 66Bc, 66Bm, 66By, and 66Bp control the ink ejection timing based on the image data by the inkjet heads 56C, 56M, 56Y, and 56P of the print unit 23B based on the output pulse signal of the encoder 22B, respectively. Execute printing.

  The print start count value corresponding to the print control unit 66Bc is larger than the print start count value corresponding to the print control unit 66Bk by the distance between the inkjet heads 56K and 56C of the print unit 23B. Similarly, the print start count values corresponding to the print control units 66Bm, 66By, 66Bp are increased by the distance between the inkjet heads 56C, 56M, between the inkjet heads 56M, 56Y, and between the inkjet heads 56Y, 56P, respectively. Is set to

  When printing based on the image data by the inkjet heads 56 of the printing units 23A and 23B is completed, the print control unit 66Ak conveys the web W to the conveyance control unit 62, the unwinding device control unit 13, and the winding device control unit 73. Instruct the end.

  When the end of conveyance of the web W is instructed, the conveyance control unit 62 stops the conveyance motor 44, the unwinding device control unit 13 stops the brake 12, and the winding device control unit 73 stops the winding motor 72. . Thereby, conveyance of the web W is complete | finished and a series of operation | movement is complete | finished.

  As described above, in the printing apparatus 3, the printing apparatus control unit 24 controls the ejection timing of ink in each inkjet head 56 of the printing unit 23A based on the output pulse signal of the encoder 22A from the conveyance start timing of the web W. To do. Further, the printing apparatus control unit 24 controls ink ejection timing in each inkjet head 56 of the printing unit 23B based on the output pulse signal of the encoder 22B from the conveyance start timing of the web W.

  In this way, by controlling the ink ejection timing in the printing units 23A and 23B using the encoders 22A and 22B arranged in the vicinity thereof, ink landing between the inkjet heads 56 in both the printing units 23A and 23B. Misalignment can be suppressed. As a result, a decrease in print image quality can be suppressed.

  Here, unlike the present embodiment, when the ink ejection timing in the printing units 23A and 23B is controlled using only the encoder 22A without providing the encoder 22B, the printing unit 23B is far from the encoder 22A. For this reason, the output pulse signal of the encoder 22A is likely to be displaced with respect to the actual movement of the web W at the position of the printing unit 23B. For this reason, in the printing unit 23 </ b> B, there is a possibility that a deviation of the ink landing position between the inkjet heads 56 due to a decrease in ink landing accuracy may occur.

  In this case, the presence of guide rollers 35 and 36 that are folding rollers between the encoder 22A and the printing unit 23B also causes a shift in the ink landing position between the inkjet heads 56 in the printing unit 23B. It becomes a factor. That is, since the folding roller is required to have high strength and the roller diameter of the folding roller is large, the mechanical tolerance of the roundness greatly affects the tension fluctuation (speed fluctuation) of the web W. As a result, the output pulse signal of the encoder 22A is likely to deviate from the actual movement of the web W at the position of the printing unit 23B. As a result, the landing position of the ink between the inkjet heads 56 in the printing unit 23B is likely to shift.

  On the other hand, in this embodiment, as described above, by using the encoders 22A and 22B arranged in the vicinity of the printing units 23A and 23B, between the inkjet heads 56 in both the printing units 23A and 23B. The deviation of the ink landing position can be suppressed.

  In the printing apparatus 3, the printing units 23A and 23B are controlled based on the output signals of the encoders 22A and 22B from the common control start timing (web W conveyance start timing). The mark on the web W, which is a mark for starting counting the number of output pulses of the encoders 22A and 22B, is unnecessary. For this reason, a mechanism for placing a mark on the web W and a sensor for detecting the mark are not required, and thus the complexity of the apparatus configuration can be suppressed.

  Therefore, according to the printing apparatus 3, it is possible to reduce the deterioration of the printing image quality while suppressing the complexity of the apparatus configuration.

  The encoders 22A and 22B are installed on guide rollers 34 and 36 that are folding rollers provided at positions where the web W is bent. That is, since the encoders 22A and 22B are installed on the guide rollers 34 and 36 which are folding rollers that hardly cause the web W to slip, it is possible to suppress the output pulse signal from being shifted from the actual movement of the web W. . Thereby, since the fall of the ink landing position precision in printing part 23A, 23B is suppressed, the fall of printing image quality can be reduced more.

  In the above-described embodiment, one encoder 22 corresponding to each printing unit 23 is installed, but a plurality of encoders 22 installed on different rollers are arranged for one printing unit 23. Also good.

  For example, the encoder 22 corresponding to the printing unit 23 </ b> A may be installed on the guide roller 35. In this case, for example, the encoder 22A installed on the guide roller 34 is used for controlling the inkjet heads 56K, 56C of the printing unit 23A, and the encoder 22 installed on the guide roller 35 is used for controlling the inkjet heads 56M, 56Y, 56P. What should I do? For example, the encoder 22 corresponding to the printing unit 23 </ b> B may be installed in the guide roller 37. In this case, for example, the encoder 22B installed on the guide roller 36 is used for controlling the inkjet heads 56K, 56C of the printing unit 23B, and the encoder 22 installed on the guide roller 37 is used for controlling the inkjet heads 56M, 56Y, 56P. What should I do? When a plurality of encoders 22 are provided for one printing unit 23, at least one inkjet head 56 corresponds to each encoder 22, and each encoder 22 is used to control the corresponding inkjet head 56.

  The roller on which the encoder 22 is installed may be a roller that is not a folding roller. For example, a roller that is driven and rotated by the web W may be provided in the middle of the printing unit 23, that is, between the guide rollers 34 and 35 or between the guide rollers 36 and 37, and the encoder 22 may be installed on the roller. The roller (first roller) on which the encoder 22 corresponding to the printing unit 23A is installed may be provided near or in the middle of the printing unit 23A on the upstream side of the printing unit 23B. The roller (second roller) on which the encoder 22 corresponding to the printing unit 23B is installed is downstream of the printing unit 23A and downstream of the most downstream roller on which the encoder 22 corresponding to the printing unit 23A is provided. In this case, it may be provided near or in the middle of the printing unit 23B.

  Further, in the case where a plurality of encoders 22 are provided for one printing unit 23, when an abnormality is found in the output pulse signals of some of the encoders 22, at least one other than the encoder 22 in which an abnormality is found in the output pulse signal. The ink ejection timing in each inkjet head 56 may be controlled using two encoders 22.

  For example, it is assumed that there are two encoders 22A installed on the guide roller 34 and encoder 22 installed on the guide roller 35 as the encoder 22 used for controlling the ink ejection timing in each inkjet head 56 of the printing unit 23A. The encoder 22A installed on the guide roller 34 corresponds to the inkjet heads 56K and 56C of the printing unit 23A, and the encoder 22 installed on the guide roller 35 corresponds to the inkjet heads 56M, 56Y, and 56P.

  In this case, for example, it is assumed that an abnormality is found in the output pulse signal of the encoder 22 installed on the guide roller 35. In this case, the ejection timing of ink in all the inkjet heads 56K, 56C, 56M, 56Y, and 56P of the printing unit 23A is controlled by using the encoder 22A installed on the guide roller 34 that has no abnormality in the output pulse signal. You can do it.

  Further, for example, there are two encoders 22, which are installed in the guide roller 36 and encoder 22, which is installed in the guide roller 37, as the encoder 22 used for controlling the ink ejection timing in each inkjet head 56 of the printing unit 23 </ b> B. To do. The encoder 22B installed on the guide roller 36 corresponds to the inkjet heads 56K and 56C of the printing unit 23B, and the encoder 22 installed on the guide roller 37 corresponds to the inkjet heads 56M, 56Y, and 56P.

  In this case, for example, it is assumed that an abnormality is found in the output pulse signal of the encoder 22 installed on the guide roller 37. In this case, using the encoder 22B installed on the guide roller 36, which has no abnormality in the output pulse signal, the ink ejection timing in all the inkjet heads 56K, 56C, 56M, 56Y, 56P of the printing unit 23B is controlled. You can do it.

  As a result, even if there is an abnormality in the output pulse signal of some of the encoders 22 corresponding to one printing unit 23, the encoder 22 is excluded and another encoder 22 is used. A decrease in ink landing accuracy can be suppressed.

  Here, the abnormality of the output pulse signal of the encoder 22 includes, for example, disturbance of the pulse period. Such an abnormality in the output pulse signal of the encoder 22 is caused by, for example, a large eccentricity of the roller on which the encoder 22 is installed or a slip of the web W with respect to the roller on which the encoder 22 is installed. It is.

  In the above-described embodiment, the web W conveyance start timing is the ink discharge control start timing based on the output pulse signals of the encoders 22A and 22B. However, the control start timing is not limited thereto. For example, the ink ejection control start timing based on the output pulse signals of the encoders 22A and 22B may be set to the timing when the web W conveyance speed reaches the print conveyance speed.

  In the above-described embodiment, a printing apparatus including an inkjet head as a printing mechanism has been described. However, the printing mechanism may be of another type such as an electrophotographic method.

  In the above-described embodiment, the configuration in which the unwinding device and the winding device are connected to the printing device as separate devices has been described. However, a configuration in which the unwinding unit and the winding unit are incorporated in the printing device may be used.

  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.

[Appendix]
The present application discloses the following inventions.

(Appendix 1)
A first printing unit having a plurality of printing mechanisms arranged in parallel in the web conveyance direction, and printing an image on each first printing mechanism on the first surface of the web to be conveyed;
It has a plurality of printing mechanisms arranged on the downstream side of the first printing unit in the conveying direction and arranged in parallel in the conveying direction, and images are printed on the second surface of the conveyed web by the respective printing mechanisms. A second printing section for printing;
At least one first roller disposed upstream from the second printing unit and rotating in synchronization with the conveyed web;
At least one second roller disposed downstream of the first printing unit and downstream of the most downstream first roller and rotating in synchronization with the conveyed web;
At least one first encoder installed on each of the different first rollers and outputting a pulse signal in accordance with the rotation angle of the installed first roller;
At least one second encoder that is installed on each different second roller and outputs a pulse signal in accordance with the rotation angle of the installed second roller;
Based on the output pulse signal of at least one of the first encoders from the control start timing, the printing timing in each of the printing mechanisms of the first printing unit is controlled, and the output of at least one of the second encoders from the control start timing And a control unit that controls printing timing in each of the printing mechanisms of the second printing unit based on a pulse signal.

(Appendix 2)
At least one of the first roller on which the first encoder is installed and the second roller on which the second encoder is installed is a folding roller provided at a position where the web bends. The printing apparatus according to appendix 1.

(Appendix 3)
A plurality of first encoders each corresponding to at least one of the printing mechanisms of the first printing unit;
The controller is
The printing timing of each printing mechanism of the first printing unit is controlled based on the output pulse signal of the first encoder corresponding to each printing mechanism,
In the case where an abnormality is found in the output pulse signals of some of the first encoders of the plurality of first encoders, at least one of the first encoders other than the first encoder in which an abnormality is found in the output pulse signal. The printing apparatus according to appendix 1 or 2, wherein a printing timing in each of the printing mechanisms of the first printing unit is controlled based on an output pulse signal.

(Appendix 4)
A plurality of second encoders each corresponding to at least one of the printing mechanisms of the second printing unit;
The controller is
The printing timing in each printing mechanism of the second printing unit is controlled based on the output pulse signal of the second encoder corresponding to each printing mechanism,
When an abnormality is found in the output pulse signal of a part of the second encoders of the plurality of second encoders, the abnormality of the output pulse signal is detected by at least one second encoder other than the second encoder. The printing apparatus according to any one of appendices 1 to 3, wherein a printing timing in each of the printing mechanisms of the second printing unit is controlled based on an output pulse signal.

DESCRIPTION OF SYMBOLS 1 Printing system 2 Unwinding device 3 Printing device 4 Winding device 21 Conveyance part 22, 22A, 22B Encoder 23, 23A, 23B Printing part 24 Printing apparatus control part 31-40 Guide roller 41 Head lower roller 42 Meander control part 43 Conveyance Roller 44 Conveyance motor 46, 47 Meander control roller 48 Meander control motor 51, 51K, 51C, 51M, 51Y, 51P Head unit 56, 56K, 56C, 56M, 56Y, 56P Inkjet head 61 Main control unit 62 Conveyance control unit 66, 66Ak, 66Ac, 66Am, 66Ay, 66Ap Print control unit 66Bk, 66Bc, 66Bm, 66By, 66Bp Print control unit

Claims (4)

A first printing unit having a plurality of printing mechanisms arranged in parallel in the web conveyance direction, and printing an image on each first printing mechanism on the first surface of the web to be conveyed;
It has a plurality of printing mechanisms arranged on the downstream side of the first printing unit in the conveying direction and arranged in parallel in the conveying direction, and images are printed on the second surface of the conveyed web by the respective printing mechanisms. A second printing section for printing;
At least one first roller disposed upstream from the second printing unit and rotating in synchronization with the conveyed web;
At least one second roller disposed downstream of the first printing unit and downstream of the most downstream first roller and rotating in synchronization with the conveyed web;
At least one first encoder installed on each of the different first rollers and outputting a pulse signal in accordance with the rotation angle of the installed first roller;
At least one second encoder that is installed on each different second roller and outputs a pulse signal in accordance with the rotation angle of the installed second roller;
Based on the output pulse signal of at least one of the first encoders from the control start timing, the printing timing in each of the printing mechanisms of the first printing unit is controlled, and the output of at least one of the second encoders from the control start timing And a control unit that controls printing timing in each of the printing mechanisms of the second printing unit based on a pulse signal.   At least one of the first roller on which the first encoder is installed and the second roller on which the second encoder is installed is a folding roller provided at a position where the web bends. The printing apparatus according to claim 1. A plurality of first encoders each corresponding to at least one of the printing mechanisms of the first printing unit;
The controller is
The printing timing of each printing mechanism of the first printing unit is controlled based on the output pulse signal of the first encoder corresponding to each printing mechanism,
In the case where an abnormality is found in the output pulse signals of some of the first encoders of the plurality of first encoders, at least one of the first encoders other than the first encoder in which an abnormality is found in the output pulse signal. The printing apparatus according to claim 1, wherein a printing timing in each of the printing mechanisms of the first printing unit is controlled based on an output pulse signal. A plurality of second encoders each corresponding to at least one of the printing mechanisms of the second printing unit;
The controller is
The printing timing in each printing mechanism of the second printing unit is controlled based on the output pulse signal of the second encoder corresponding to each printing mechanism,
When an abnormality is found in the output pulse signal of a part of the second encoders of the plurality of second encoders, the abnormality of the output pulse signal is detected by at least one second encoder other than the second encoder. 4. The printing apparatus according to claim 1, wherein a printing timing in each printing mechanism of the second printing unit is controlled based on an output pulse signal. 5.