JP2017052586A - Conveyance device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a conveyance device which can suppress the tension fluctuation of a web.SOLUTION: A printer 1 having a conveyance device includes: a main shaft roller 37 which conveys a web; an in-feed roller 48 which is arranged on the downstream side of the main shaft roller 37 in the conveyance direction of the web and conveys the web to the further downstream side; an encoder which detects the conveyance speed by the main shaft roller 37; and a pulse conversion part and rewinder control part 54 which control the conveyance speed by the in-feed roller 48 so that the conveyance speed by the in-feed roller 48 becomes equal to the conveyance speed by the main shaft roller 37 on the basis of the conveyance speed by the main shaft roller 37 detected by the encoder.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a conveyance device that conveys a web.

  2. Description of the Related Art A conveyance device that continuously conveys a long web printed by a printing apparatus is known.

  In general, a web conveying device is provided with a dancer roller for maintaining the tension of the web (see, for example, Patent Document 1). The dancer roller keeps the web tension by pushing down the web by its own weight. The dancer roller moves up and down due to fluctuations in the amount of sag of the web in accordance with the speed difference between the two conveyance rollers that convey the web.

  In such a transport apparatus, web transport speed control using a dancer roller is performed. Specifically, the conveyance speed by the conveyance roller on the downstream side is controlled in accordance with on / off of a sensor that detects the presence or absence of the dancer roller at a predetermined height position. Thereby, with a simple configuration, the speed difference between the conveying rollers can be suppressed, and the web tension can be maintained.

Japanese Patent Laid-Open No. 5-116823

  However, in the web conveyance speed control using the dancer roller described above, when the sensor is turned on or off, the downstream conveyance roller suddenly accelerates or decelerates, which causes web tension fluctuations. May be. If tension changes in the web being printed, the print quality may be reduced.

  The present invention has been made in view of the above, and an object of the present invention is to provide a conveyance device that can suppress a change in web tension.

  In order to achieve the above object, the first feature of the transport device according to the present invention is a first transport roller for transporting a web, and a downstream side of the first transport roller in the web transport direction. Based on the second conveyance roller that conveys to the downstream side, the speed detection unit that detects the conveyance speed by the first conveyance roller, and the conveyance speed by the first conveyance roller that is detected by the speed detection unit, the second conveyance roller And a controller that controls the conveyance speed by the second conveyance roller so that the conveyance speed by the roller is equal to the conveyance speed by the first conveyance roller.

  The 2nd characteristic of the conveying apparatus which concerns on this invention is arrange | positioned in the downstream of the said 1st conveyance roller in the conveyance direction of a web with the 1st conveyance roller which conveys a web, and the 2nd which conveys a web further downstream. A conveyance roller, a speed detection unit that detects a conveyance speed by the first conveyance roller, and a dancer roller that moves up and down according to fluctuations in the amount of sag of the web between the first conveyance roller and the second conveyance roller; A dancer roller detection unit that detects the presence or absence of the dancer roller at a predetermined height position, and controls a conveyance speed by the second conveyance roller according to a change in the detection result of the dancer roller by the dancer roller detection unit At the same time, based on the transport speed by the first transport roller detected by the speed detector, the transport speed by the second transport roller is changed to the first transport roller. In that a control unit for controlling the conveying speed by the equal as the second conveying roller and the conveying speed of la.

  A third feature of the transport apparatus according to the present invention is that the control unit includes a factor related to a transport speed by the first transport roller, a factor related to a detected value of the transport speed by the speed detection unit, and transport by the second transport roller. Using a constant corresponding to a factor related to speed, the transport speed by the second transport roller that is equal to the transport speed by the first transport roller is calculated from the transport speed by the first transport roller detected by the speed detector. There is to do.

  A fourth feature of the transport device according to the present invention is that the factor related to the transport speed by the first transport roller and the factor related to the transport speed by the second transport roller include a web thickness, Using the constant according to the thickness of the web, the transport speed by the second transport roller that is equal to the transport speed by the first transport roller is equal to the transport speed by the first transport roller detected by the speed detection unit. It is to calculate.

  According to the first feature of the transport apparatus according to the present invention, the control unit is configured such that the transport speed by the second transport roller is based on the transport speed by the first transport roller detected by the speed detection unit. The conveyance speed by the second conveyance roller is controlled to be equal to the speed. Thereby, since it is suppressed that a speed difference arises between a 1st conveyance roller and a 2nd conveyance roller, the fluctuation | variation of the amount of sagging of a web is suppressed. For this reason, sudden acceleration and sudden deceleration of the second transport roller that occur when the transport speed of the second transport roller is controlled in accordance with fluctuations in the amount of sag of the web can be suppressed. Thereby, the tension | tensile_strength fluctuation | variation of a web can be suppressed.

  According to the second feature of the transport apparatus according to the present invention, the control unit is configured such that the transport speed by the second transport roller is transported by the first transport roller based on the transport speed by the first transport roller detected by the speed detection unit. The conveyance speed by the second conveyance roller is controlled to be equal to the speed. Thereby, since it is suppressed that a speed difference arises between a 1st conveyance roller and a 2nd conveyance roller, the fluctuation | variation of the amount of sagging of a web is suppressed. For this reason, the situation which controls the conveyance speed by a 2nd conveyance roller according to the change of the detection result of a dancer roller can be reduced. Thereby, sudden acceleration and sudden deceleration of the second transport roller are suppressed. As a result, web tension fluctuations can be suppressed.

  According to the third feature of the conveying apparatus according to the present invention, the control unit relates to a factor related to the conveying speed by the first conveying roller, a factor related to the detected value of the conveying speed by the speed detecting unit, and a conveying speed by the second conveying roller. Using the constant according to the factor, the transport speed by the second transport roller that is equal to the transport speed by the first transport roller is calculated from the transport speed by the first transport roller detected by the speed detector. Thereby, the conveyance speed by a 1st conveyance roller and the conveyance speed by a 2nd conveyance roller can be match | combined with high precision.

  According to the 4th characteristic of the conveying apparatus which concerns on this invention, a control part uses the constant according to the thickness of a web, and the 1st conveyance from the conveyance speed by the 1st conveyance roller detected by the speed detection part. A transport speed by the second transport roller that is equal to the transport speed by the roller is calculated. Thereby, it can respond to the change of the thickness of a web.

It is a schematic block diagram of a printing apparatus provided with the conveying apparatus which concerns on embodiment. FIG. 2 is a block diagram for explaining a configuration of a main part of a printer unit and a rewinder unit of the printing apparatus shown in FIG. 1. It is a figure which shows an example of the circumferential speed of the roller which conveys a web, and the conveyance speed of a web. It is a flowchart of an in-feed roller speed adjustment process.

  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 apparatus including a transport device according to an embodiment of the present invention. FIG. 2 is a block diagram for explaining the configuration of the main parts of the printer unit and the rewinder unit of the printing apparatus shown in FIG. 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 FIG. 1, the printing apparatus 1 according to the present embodiment includes an unwinder unit 2, a printer unit 3, and a rewinder unit 4. In addition, the conveyance apparatus of a claim has the spindle roller 37 mentioned later, the encoder 45, the infeed roller 48, the rewinder control part 54, and the pulse conversion part 64. FIG.

  The unwinder unit 2 unwinds the web W, which is a long print medium made of paper, film, or the like, to the printer unit 3. The unwinder unit 2 includes a web roll support shaft 11, a first buffer unit 12, an outfeed roller 13, a nip roller 14, a second buffer unit 15, and an unwinder control unit 16.

  The web roll support shaft 11 supports the web roll 17 in a rotatable manner. The web roll support shaft 11 is formed in a long shape extending in the front-rear direction. The web roll 17 is a roll of the web W. The web roll support shaft 11 is driven to rotate clockwise in FIG. 1 by a motor (not shown). The web roll 17 rotates in the same direction by the rotation of the web roll support shaft 11, and the web W is unwound to the downstream side (right side).

  The first buffer unit 12 holds the slack of the web W between the web roll support shaft 11 and the outfeed roller 13. The first buffer unit 12 includes support rollers 18 and 19 and a dancer roller 20.

  The support rollers 18 and 19 support the web W between the web roll 17 and the outfeed roller 13. The support rollers 18 and 19 are arranged at the same height and spaced apart from each other by a predetermined distance in the left-right direction.

  The dancer roller 20 pushes down the web W by its own weight between the support rollers 18 and 19. As a result, the slack of the web W between the web roll support shaft 11 and the outfeed roller 13 is absorbed by the first buffer portion 12, and the tension of the web W is maintained. The dancer roller 20 moves up and down due to fluctuations in the amount of sag of the web W according to the speed difference of the web W between the web roll support shaft 11 and the outfeed roller 13.

  The outfeed roller 13 conveys the web W unwound from the web roll 17 toward the printer unit 3 while being nipped with the nip roller 14. The outfeed roller 13 is disposed between the first buffer unit 12 and the second buffer unit 15. The outfeed roller 13 is rotationally driven by a motor (not shown).

  The nip roller 14 conveys the web W unwound from the web roll 17 while being nipped with the outfeed roller 13. The nip roller 14 is disposed adjacent to the upper side of the outfeed roller 13. The nip roller 14 is driven to rotate by the outfeed roller 13 via the web W.

  The second buffer unit 15 absorbs the speed difference of the web W between the outfeed roller 13 and a tension applying roller 27 of the printer unit 3 described later. The second buffer unit 15 includes support rollers 21 and 22 and a web floating suppression unit 23.

  The support rollers 21 and 22 support the web W while maintaining the slack of the web W between the outfeed roller 13 and a guide roller 26 of the printer unit 3 described later. The support rollers 21 and 22 are spaced apart from each other by a predetermined distance in the left-right direction and are disposed at the same height.

  The web lifting suppression unit 23 suppresses lifting due to fluctuations in the behavior of the web W between the support rollers 21 and 22.

  The unwinder control unit 16 controls the entire operation of the unwinder unit 2. The unwinder control unit 16 includes a CPU, a memory, a clock (internal clock), and the like.

  The printer unit 3 prints on the web W while transporting the web W transported from the unwinder unit 2. The printer unit 3 includes a guide roller 26, a pair of tension applying rollers 27, a brake 28, a tension detection roller 29, tension detection auxiliary rollers 30 and 31, a tension sensor 32, guide rollers 33 and 34, Five head support rollers 35, a guide roller 36, a main shaft roller (corresponding to the first transport roller in the claims) 37, a nip roller 38, a guide roller 39, four ink jet heads 40, and a printer control unit 41.

  The guide roller 26 guides the web W between the support roller 22 and the tension applying roller 27 of the unwinder unit 2.

  The pair of tension applying rollers 27 applies tension to the web W. The pair of tension applying rollers 27 nip the web W and follow the web W conveyed by the main shaft roller 37 and the nip roller 38. When one of the tension applying rollers 27 is braked by the brake 28, tension is applied to the web W between the main shaft roller 37 and the tension applying roller 27.

  The brake 28 brakes one tension applying roller 27. The brake 28 is a powder brake, for example.

  The tension detection roller 29 is a member around which the web W is wound in order to detect the tension of the web W. A web W is wound around the tension detection roller 29 from above.

  The tension detection auxiliary rollers 30 and 31 assist the winding of the web W around the tension detection roller 29. The tension detection auxiliary rollers 30 and 31 are spaced apart from each other in the left-right direction with the tension detection roller 29 interposed therebetween, and are disposed below the tension detection roller 29. The tension detection auxiliary rollers 30 and 31 press the web W from above on the upstream side (left side) and the downstream side (right side) of the tension detection roller 29, respectively.

  The tension sensor 32 detects the tension of the web W by receiving and detecting a load corresponding to the tension of the web W from the tension detection roller 29.

  The guide rollers 33 and 34 guide the web W between the tension detection auxiliary roller 31 and the uppermost head lower support roller 35.

  The head lower support roller 35 supports the web W below the inkjet head 40. The five head lower support rollers 35 are arranged between the guide roller 34 and the guide roller 36 so as to draw a convex arch. As a result, the web W is stretched between the head lower support rollers 35, and the web W is maintained in a stable posture.

  The guide roller 36 guides the web W between the most downstream head lower support roller 35 and the main shaft roller 37.

  The main shaft roller 37 conveys the web W toward the rewinder unit 4 while nipping the web W with the nip roller 38. As shown in FIG. 2, a spindle motor 42 is connected to the spindle roller 37 via a speed reducer 43. The spindle motor 42 generates a rotational driving force for rotating the spindle roller 37 under the control of the printer control unit 41. The reducer 43 transmits the rotational driving force of the spindle motor 42 to the spindle roller 37 at a predetermined reduction ratio.

  Further, an encoder 45 (corresponding to a speed detection unit in claims) 45 is connected to the spindle roller 37 via a speed reducer 44. The reducer 44 transmits the rotation of the spindle roller 37 to the encoder 45 at a predetermined reduction ratio. The encoder 45 outputs a pulse signal for each predetermined rotation angle of the main shaft roller 37.

  The nip roller 38 conveys the web W while being nipped with the main shaft roller 37. The nip roller 38 is disposed adjacent to the lower side of the main shaft roller 37. The nip roller 38 is driven to rotate by the main shaft roller 37 via the web W.

  The guide roller 39 guides the web W between the main shaft roller 37 and a guide roller 46 of the rewinder unit 4 described later.

  The inkjet head 40 prints by ejecting ink onto the web W being conveyed. The four inkjet heads 40 are arranged above the lower head support roller 35 at intervals along the web W conveyance direction.

  The printer control unit 41 controls the operation of the entire printer unit 3. The printer control unit 41 includes a CPU, a memory, a clock (internal clock), and the like.

  The rewinder unit 4 winds up the web W printed by the printer unit 3. The rewinder unit 4 includes a guide roller 46, a third buffer unit 47, an in-feed roller (equivalent to the second transport roller in the claims) 48, a nip roller 49, a fourth buffer unit 50, and a pair of tension applying rollers. 51, a brake 52, a winding shaft 53, and a rewinder control unit 54.

  The guide roller 46 guides the web W between a guide roller 39 of the printer unit 3 and a support roller 55 described later.

  The third buffer unit 47 holds the slack of the web W between the main shaft roller 37 and the infeed roller 48 of the printer unit 3. The third buffer unit 47 includes support rollers 55 and 56, a dancer roller 57, and a dancer sensor (corresponding to a dancer roller detection unit in claims) 58.

  The support rollers 55 and 56 support the web W between the guide roller 46 and the infeed roller 48. The support rollers 55 and 56 are spaced apart from each other by a predetermined distance in the left-right direction and are disposed at the same height.

  The dancer roller 57 pushes down the web W by its own weight between the support rollers 55 and 56. Thereby, the slack of the web W between the spindle roller 37 and the infeed roller 48 of the printer unit 3 is absorbed by the third buffer unit 47, and the tension of the web W is maintained. The dancer roller 57 moves up and down due to fluctuations in the amount of sag of the web W according to the speed difference of the web W between the main shaft roller 37 and the in-feed roller 48 of the printer unit 3.

  The dancer sensor 58 detects the presence or absence of the dancer roller 57 at a predetermined height position.

  The in-feed roller 48 conveys the web W fed from the printer unit 3 toward the take-up shaft 53 while being nipped with the nip roller 49. The infeed roller 48 is disposed between the third buffer unit 47 and the fourth buffer unit 50. As shown in FIG. 2, an infeed motor 59 is connected to the infeed roller 48 via a speed reducer 60. The infeed motor 59 generates a rotational driving force for rotating the infeed roller 48 under the control of the rewinder controller 54. The reducer 60 transmits the rotational driving force of the infeed motor 59 to the infeed roller 48 at a predetermined reduction ratio.

  The nip roller 49 conveys the web W while nipping it with the in-feed roller 48. The nip roller 49 is disposed adjacent to the upper side of the infeed roller 48. The nip roller 49 is driven to rotate by the infeed roller 48 via the web W.

  The fourth buffer unit 50 holds the slack of the web W between the in-feed roller 48 and the tension applying roller 51. The fourth buffer unit 50 includes support rollers 61 and 62 and a dancer roller 63.

  The support rollers 61 and 62 support the web W between the in-feed roller 48 and the tension applying roller 51. The support rollers 61 and 62 are disposed at the same height and spaced apart from each other by a predetermined distance in the left-right direction.

  The dancer roller 63 pushes down the web W by its own weight between the support rollers 61 and 62. Thereby, the slack of the web W between the in-feed roller 48 and the tension applying roller 51 is absorbed by the fourth buffer unit 50, and the tension of the web W is maintained. The dancer roller 63 moves up and down due to fluctuations in the amount of sag of the web W according to the speed difference of the web W between the infeed roller 48 and the tension applying roller 51.

  The pair of tension applying rollers 51 applies tension to the web W. The pair of tension applying rollers 51 are rotated around the web W wound up by the winding shaft 53 while the web W is nipped. When one of the tension applying rollers 51 is braked by the brake 52, tension is applied to the web W taken up by the take-up shaft 53. Thereby, wrinkles and the like can be prevented from occurring on the web W wound around the winding shaft 53.

  The brake 52 brakes one tension applying roller 51. The brake 52 is a powder brake, for example.

  Instead of the pair of tension applying rollers 51 and the brake 52, the brake device may be configured by three or more rollers and a brake.

  The winding shaft 53 winds and holds the web W. The winding shaft 53 is formed in a long shape extending in the front-rear direction. The winding shaft 53 is driven to rotate clockwise in FIG. 1 by a motor (not shown). The web W is wound around the winding shaft 53 by the rotation of the winding shaft 53.

  The rewinder control unit 54 controls the overall operation of the rewinder unit 4. The rewinder control unit 54 includes a CPU, a memory, a clock (internal clock), and the like.

  The rewinder controller 54 receives a pulse signal from the pulse converter 64 shown in FIG. 2 provided in the rewinder unit 4. The rewinder controller 54 controls the conveyance speed by the infeed roller 48 based on the pulse signal from the pulse converter 64. In addition, the rewinder control part 54 and the pulse conversion part 64 comprise the control part of a claim.

  Further, the rewinder control unit 54 controls the conveyance speed by the infeed roller 48 according to the change in the detection result of the dancer roller 57 by the dancer sensor 58. Specifically, the rewinder control unit 54 changes the web W when the amount of sag of the web W varies in the third buffer unit 47 and the dancer roller 57 moves up and down to switch the dancer sensor 58 on and off. The conveyance speed by the in-feed roller 48 is controlled so as to cancel the fluctuation of the amount of slack.

  The pulse conversion unit 64 converts the pulse signal output from the encoder 45 into a pulse signal indicating the conveyance speed VL calculated by the following equation (1), and outputs the pulse signal after the frequency conversion to the rewinder control unit 54. To do.

VL = a × VH + b (1)
Here, VH is a detection value by the encoder 45 of the conveyance speed by the spindle roller 37. VL is a conveyance speed by the infeed roller 48. a and b are constants for calculating the conveyance speed VL by the in-feed roller 48 that is equal to the conveyance speed by the main shaft roller 37. “a” and “b” are constants corresponding to a factor relating to the conveyance speed by the spindle roller 37, a factor relating to the detected value of the conveyance speed by the encoder 45, and a factor relating to the conveyance speed by the infeed roller 48.

  Factors relating to the conveying speed of the main shaft roller 37 include the diameter of the main shaft roller 37, the reduction ratio of the speed reducer 43, the thickness of the web W, and the clock (internal clock) error in the printer control unit 41. Factors relating to the detected value of the conveyance speed by the encoder 45 include the reduction ratio of the speed reducer 44 and the resolution of the encoder 45. Factors relating to the conveyance speed by the infeed roller 48 include the diameter of the infeed roller 48, the reduction ratio of the speed reducer 60, the thickness of the web W, and an error in the clock (internal clock) in the rewinder control unit 54.

  The constant a is a constant (speed proportional constant) according to a factor whose degree of influence on the speed is proportional to the speed. Factors related to the constant a include a fixed constant of design parameters of the component parts and the thickness of the web W. The fixed constants of the design parameters of the component parts are the diameters of the spindle roller 37 and the infeed roller 48, the reduction ratios of the speed reducers 43, 44, 60, the resolution of the encoder 45, and the like.

  Here, an example of the peripheral speed of the roller which conveys the web W, and the conveyance speed of the web W are shown in FIG. In the example of FIG. 3, the thickness of the web W is 0.1 mm. As shown in FIG. 3, a speed difference is generated between the peripheral speed of the roller and the conveyance speed of the web W. This speed difference varies depending on the thickness of the web W. That is, a difference occurs in the conveyance speed depending on the thickness of the web W.

  In addition, a difference occurs in the conveyance speed of the roller depending on the diameter of the roller that conveys the web W and the reduction ratio between the motor and the roller. The speed difference caused by the thickness of the web W, the diameter of the roller, and the speed reduction ratio increases as the speed increases. The influence of such a factor proportional to the speed is represented by a constant a as a speed proportional component.

  The constant b is a constant (speed difference constant) corresponding to a factor whose degree of influence on the speed is not proportional to the speed. As a factor related to the constant b, there is a clock (internal clock) error in the printer control unit 41 and the rewinder control unit 54. Further, an error at the time of speed measurement when acquiring constants a and b, which will be described later, is also included in the factors related to the constant b.

  The constants a and b are acquired in advance and stored in the pulse conversion unit 64. Acquisition of the constants a and b is performed as follows. That is, in the printing apparatus 1, while the web W is being transported, a transport speed by the spindle roller 37 and a transport speed by the infeed roller 48 are measured using a speed measuring device such as a laser Doppler speedometer. This speed measurement is performed for a set speed of the plurality of spindle rollers 37. Then, constants a and b are calculated using a plurality of speed measurement results.

  Here, the constant a varies depending on the thickness of the web W. Therefore, a constant a corresponding to the thickness of the plurality of webs W used in the printing apparatus 1 is acquired and stored in the pulse converter 64.

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

  When printing is performed by the printing apparatus 1, first, the unwinder control unit 16, the printer control unit 41, and the rewinder control unit 54 start conveyance of the web W. Specifically, the unwinder control unit 16 starts to rotate the web roll support shaft 11 and the outfeed roller 13. The printer control unit 41 activates the brake 28 and activates the spindle motor 42 to start the rotation drive of the spindle roller 37. The rewinder control unit 54 activates the infeed motor 59 to start the rotational drive of the infeed roller 48 and starts the rotational drive of the take-up shaft 53. Further, the rewinder control unit 54 activates the brake 52.

  After starting the conveyance of the web W, the printer control unit 41 ejects ink from the inkjet head 40 based on the image data to be printed. Thereby, an image is printed on the web W.

  During conveyance of the web W, the printer control unit 41 controls the brake 28 based on the detection value of the tension sensor 32 so that the tension of the web W becomes constant. Further, the pulse converter 64 and the rewinder controller 54 execute an infeed roller speed adjustment process. The in-feed roller speed adjustment process will be described later.

  When the image printing is completed, the unwinder control unit 16, the printer control unit 41, and the rewinder control unit 54 end the conveyance of the web W. Specifically, the unwinder control unit 16 stops the rotational drive of the web roll support shaft 11 and the outfeed roller 13. The printer control unit 41 stops the brake 28 and stops the spindle motor 42 to stop the rotation drive of the spindle roller 37. The rewinder controller 54 stops the infeed motor 59 to stop the rotation drive of the infeed roller 48 and stops the rotation drive of the take-up shaft 53. Further, the rewinder control unit 54 stops the brake 52. Thereby, a series of operation | movement is complete | finished.

  Next, the infeed roller speed adjustment process will be described with reference to the flowchart of FIG.

  When the conveyance of the web W is started, in step S1 of FIG. 4, the pulse conversion unit 64 determines whether or not the speed calculation timing has come. The speed calculation timing is a timing for calculating the transport speed VL by the infeed roller 48 so as to be equal to the transport speed by the main shaft roller 37. The speed calculation timing is set to a timing every predetermined time. If it is determined that the speed calculation timing has not come (step S1: NO), the pulse converter 64 proceeds to step S5.

  When it is determined that the speed calculation timing has come (step S1: YES), in step S2, the pulse conversion unit 64 calculates a transport speed VL by the infeed roller 48 that is equal to the transport speed by the main shaft roller 37.

  Specifically, the pulse converter 64 calculates the detected value VH of the conveyance speed by the spindle roller 37 based on the pulse signal input from the encoder 45. Next, the pulse conversion unit 64 calculates the conveyance speed VL by the infeed roller 48 using the detected value VH and the constants a and b according to the above equation (1). Here, the pulse converter 64 uses a value corresponding to the thickness of the web W being conveyed as the constant a.

  Next, in step S3, the pulse converter 64 converts the frequency of the pulse signal input from the encoder 45 into a pulse signal indicating the transport speed VL calculated in step S2. The pulse converter 64 outputs the pulse signal after the frequency conversion to the rewinder controller 54.

  Next, in step S <b> 4, the rewinder controller 54 controls the infeed motor 59 based on the pulse signal input from the pulse converter 64 to adjust the conveyance speed by the infeed roller 48. Thereby, the conveyance speed by the main shaft roller 37 and the conveyance speed by the infeed roller 48 become equal. Thereafter, the process proceeds to step S5.

  In step S5, the pulse conversion unit 64 determines whether or not the conveyance of the web W has been completed. When it is determined that the conveyance of the web W has not ended (step S5: NO), the pulse conversion unit 64 returns to step S1. When the pulse conversion unit 64 determines that the conveyance of the web W has ended (step S5: YES), the infeed roller speed adjustment process ends.

  When the dancer sensor 57 is turned on and off by moving the dancer roller 57 up and down due to the amount of sag of the web W changing in the third buffer unit 47 during the conveyance of the web W, the rewinder control unit 54 Controls the conveyance speed by the in-feed roller 48 so as to cancel the fluctuation of the amount of sag of the web W. In this case, sudden acceleration or sudden deceleration of the infeed roller 48 may occur, which may cause fluctuations in the tension of the web W.

  However, as long as the web W is normally conveyed, the conveyance speed by the main shaft roller 37 and the conveyance speed by the infeed roller 48 are equalized by the infeed roller speed adjustment processing, so the dancer roller 57 moves up and down. Is suppressed. Therefore, as long as the web W is transported normally, the situation where the control of the infeed roller 48 based on the on / off of the dancer sensor 58 as described above does not occur.

  As described above, in the printing apparatus 1, based on the transport speed by the main shaft roller 37 detected by the encoder 45, the transport by the infeed roller 48 is equal to the transport speed by the infeed roller 48. Control the speed. Specifically, the pulse converter 64 calculates the transport speed VL by the infeed roller 48 that is equal to the transport speed by the main shaft roller 37 from the detection value VH by the encoder 45 of the transport speed by the main shaft roller 37. The pulse converter 64 converts the frequency of the pulse signal input from the encoder 45 into a pulse signal indicating the calculated transport speed VL. The rewinder controller 54 controls the conveyance speed by the infeed roller 48 based on the pulse signal after frequency conversion by the pulse converter 64.

  As a result, the occurrence of a speed difference between the main shaft roller 37 and the in-feed roller 48 is suppressed, so that fluctuations in the amount of sag of the web W can be suppressed. For this reason, the sudden movement of the infeed roller 48 that occurs when the conveyance speed of the infeed roller 48 is controlled in accordance with the fluctuation amount of the sag of the web W (change in the detection result of the dancer roller 57 by the dancer sensor 58). Acceleration and sudden deceleration are suppressed. Thereby, the tension | tensile_strength fluctuation | variation of the web W can be suppressed. As a result, it is possible to suppress a decrease in print image quality in the printer unit 3.

  In other words, the occurrence of a speed difference between the main shaft roller 37 and the in-feed roller 48 is suppressed, and fluctuations in the amount of sag of the web W are suppressed. It is possible to reduce the situation where the conveyance speed of the in-feed roller 48 is controlled according to the change in the detection result of the roller 57). Thereby, sudden acceleration and sudden deceleration of the infeed roller 48 are suppressed. As a result, the tension fluctuation of the web W can be suppressed.

  Further, the pulse conversion unit 64 uses constants a and b corresponding to factors relating to the conveyance speed by the spindle roller 37, factors relating to the detected value of the conveyance speed by the encoder 45, and factors relating to the conveyance speed by the infeed roller 48, and A transport speed VL by the in-feed roller 48 that is equal to the transport speed by the main shaft roller 37 is calculated from the detected value VH by the encoder 45 of the transport speed by the roller 37. Thereby, the conveyance speed by the spindle roller 37 and the conveyance speed by the infeed roller 48 can be matched with high accuracy.

  In the printing apparatus 1, the factor relating to the conveyance speed by the main shaft roller 37 and the factor relating to the conveyance speed by the in-feed roller 48 include the thickness of the web W. The pulse conversion unit 64 uses a constant a corresponding to the thickness of the web W to determine an infeed roller 48 that is equal to the conveyance speed of the main shaft roller 37 from the detected value VH of the conveyance speed of the main shaft roller 37 by the encoder 45. The transport speed VL is calculated. Thereby, it can respond to the change of the thickness of the web W used with the printing apparatus 1. FIG.

  The pulse conversion unit 64 is omitted, and the rewinder control unit 54 calculates the detection value VH of the conveyance speed by the spindle roller 37 from the output pulse signal of the encoder 45, and calculates the conveyance speed VL by the infeed roller 48 from the VH. You may do it.

  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 apparatus 2 Unwinder part 3 Printer part 4 Rewinder part 20,57,63 Dancer roller 37 Spindle roller 38,49 Nip roller 42 Spindle motor 43,44,60 Decelerator 45 Encoder 48 Infeed roller 54 Rewinder control part 58 Dancer sensor 59 Infeed motor 64 Pulse converter W Web

Claims (4)

A first transport roller for transporting the web;
A second transport roller disposed downstream of the first transport roller in the web transport direction and transporting the web further downstream;
A speed detector for detecting a transport speed by the first transport roller;
Based on the transport speed by the first transport roller detected by the speed detector, the transport speed by the second transport roller is controlled so that the transport speed by the second transport roller is equal to the transport speed by the first transport roller. And a control unit. A first transport roller for transporting the web;
A second transport roller disposed downstream of the first transport roller in the web transport direction and transporting the web further downstream;
A speed detector for detecting a transport speed by the first transport roller;
A dancer roller that moves up and down in response to fluctuations in the amount of sag of the web between the first transport roller and the second transport roller;
A dancer roller detector for detecting the presence or absence of the dancer roller at a predetermined height position;
According to the change of the detection result of the dancer roller by the dancer roller detection unit, the conveyance speed by the second conveyance roller is controlled, and based on the conveyance speed by the first conveyance roller detected by the speed detection unit, And a controller that controls the conveyance speed by the second conveyance roller so that the conveyance speed by the second conveyance roller is equal to the conveyance speed by the first conveyance roller.   The control unit uses the constants according to factors relating to the conveyance speed by the first conveyance roller, factors relating to the detection value of the conveyance speed by the speed detection unit, and factors relating to the conveyance speed by the second conveyance roller. The conveyance speed by the second conveyance roller that is equal to the conveyance speed by the first conveyance roller is calculated from the conveyance speed by the first conveyance roller detected by the detection unit. Transport device. The factor relating to the conveying speed by the first conveying roller and the factor relating to the conveying speed by the second conveying roller include the thickness of the web,
The control unit uses the constant according to the thickness of the web to make the second transport equal to the transport speed by the first transport roller from the transport speed by the first transport roller detected by the speed detection unit. The conveyance apparatus according to claim 3, wherein a conveyance speed by the roller is calculated.