US20180273330A1 - Transport control method, a transport apparatus, and a printing apparatus - Google Patents

Transport control method, a transport apparatus, and a printing apparatus Download PDF

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Publication number
US20180273330A1
US20180273330A1 US15/899,824 US201815899824A US2018273330A1 US 20180273330 A1 US20180273330 A1 US 20180273330A1 US 201815899824 A US201815899824 A US 201815899824A US 2018273330 A1 US2018273330 A1 US 2018273330A1
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United States
Prior art keywords
gain
drive roller
stable
transport
tension
Prior art date
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Abandoned
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US15/899,824
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English (en)
Inventor
Shoji Kakimoto
Osamu Morizono
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Screen Holdings Co Ltd
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Screen Holdings Co Ltd
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Assigned to SCREEN Holdings Co., Ltd. reassignment SCREEN Holdings Co., Ltd. ASSIGNMENT OF ASSIGNORS INTEREST (SEE DOCUMENT FOR DETAILS). Assignors: KAKIMOTO, SHOJI, MORIZONO, OSAMU
Publication of US20180273330A1 publication Critical patent/US20180273330A1/en
Abandoned legal-status Critical Current

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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B65—CONVEYING; PACKING; STORING; HANDLING THIN OR FILAMENTARY MATERIAL
    • B65H—HANDLING THIN OR FILAMENTARY MATERIAL, e.g. SHEETS, WEBS, CABLES
    • B65H23/00—Registering, tensioning, smoothing or guiding webs
    • B65H23/04—Registering, tensioning, smoothing or guiding webs longitudinally
    • B65H23/044—Sensing web tension
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B65—CONVEYING; PACKING; STORING; HANDLING THIN OR FILAMENTARY MATERIAL
    • B65H—HANDLING THIN OR FILAMENTARY MATERIAL, e.g. SHEETS, WEBS, CABLES
    • B65H20/00—Advancing webs
    • B65H20/02—Advancing webs by friction roller
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B65—CONVEYING; PACKING; STORING; HANDLING THIN OR FILAMENTARY MATERIAL
    • B65H—HANDLING THIN OR FILAMENTARY MATERIAL, e.g. SHEETS, WEBS, CABLES
    • B65H23/00—Registering, tensioning, smoothing or guiding webs
    • B65H23/04—Registering, tensioning, smoothing or guiding webs longitudinally
    • B65H23/18—Registering, tensioning, smoothing or guiding webs longitudinally by controlling or regulating the web-advancing mechanism, e.g. mechanism acting on the running web
    • B65H23/1806—Registering, tensioning, smoothing or guiding webs longitudinally by controlling or regulating the web-advancing mechanism, e.g. mechanism acting on the running web in reel-to-reel type web winding and unwinding mechanism, e.g. mechanism acting on web-roll spindle
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B65—CONVEYING; PACKING; STORING; HANDLING THIN OR FILAMENTARY MATERIAL
    • B65H—HANDLING THIN OR FILAMENTARY MATERIAL, e.g. SHEETS, WEBS, CABLES
    • B65H23/00—Registering, tensioning, smoothing or guiding webs
    • B65H23/04—Registering, tensioning, smoothing or guiding webs longitudinally
    • B65H23/18—Registering, tensioning, smoothing or guiding webs longitudinally by controlling or regulating the web-advancing mechanism, e.g. mechanism acting on the running web
    • B65H23/188—Registering, tensioning, smoothing or guiding webs longitudinally by controlling or regulating the web-advancing mechanism, e.g. mechanism acting on the running web in connection with running-web
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B65—CONVEYING; PACKING; STORING; HANDLING THIN OR FILAMENTARY MATERIAL
    • B65H—HANDLING THIN OR FILAMENTARY MATERIAL, e.g. SHEETS, WEBS, CABLES
    • B65H2301/00—Handling processes for sheets or webs
    • B65H2301/40—Type of handling process
    • B65H2301/41—Winding, unwinding
    • B65H2301/4165—Unwinding or winding material from or to one station in which the material is stored
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B65—CONVEYING; PACKING; STORING; HANDLING THIN OR FILAMENTARY MATERIAL
    • B65H—HANDLING THIN OR FILAMENTARY MATERIAL, e.g. SHEETS, WEBS, CABLES
    • B65H2515/00—Physical entities not provided for in groups B65H2511/00 or B65H2513/00
    • B65H2515/30—Forces; Stresses
    • B65H2515/31—Tensile forces
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B65—CONVEYING; PACKING; STORING; HANDLING THIN OR FILAMENTARY MATERIAL
    • B65H—HANDLING THIN OR FILAMENTARY MATERIAL, e.g. SHEETS, WEBS, CABLES
    • B65H2557/00—Means for control not provided for in groups B65H2551/00 - B65H2555/00
    • B65H2557/20—Calculating means; Controlling methods
    • B65H2557/264—Calculating means; Controlling methods with key characteristics based on closed loop control
    • B65H2557/2644—Calculating means; Controlling methods with key characteristics based on closed loop control characterised by PID control
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B65—CONVEYING; PACKING; STORING; HANDLING THIN OR FILAMENTARY MATERIAL
    • B65H—HANDLING THIN OR FILAMENTARY MATERIAL, e.g. SHEETS, WEBS, CABLES
    • B65H2801/00—Application field
    • B65H2801/03—Image reproduction devices
    • B65H2801/06—Office-type machines, e.g. photocopiers
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B65—CONVEYING; PACKING; STORING; HANDLING THIN OR FILAMENTARY MATERIAL
    • B65H—HANDLING THIN OR FILAMENTARY MATERIAL, e.g. SHEETS, WEBS, CABLES
    • B65H2801/00—Application field
    • B65H2801/03—Image reproduction devices
    • B65H2801/12—Single-function printing machines, typically table-top machines
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B65—CONVEYING; PACKING; STORING; HANDLING THIN OR FILAMENTARY MATERIAL
    • B65H—HANDLING THIN OR FILAMENTARY MATERIAL, e.g. SHEETS, WEBS, CABLES
    • B65H2801/00—Application field
    • B65H2801/03—Image reproduction devices
    • B65H2801/21—Industrial-size printers, e.g. rotary printing press

Definitions

  • This invention relates to a transport control method, a transport apparatus, and a printing apparatus for transporting an elongate printing medium in a predetermined direction.
  • a printing apparatus having this type of transport apparatus includes a paper feeder, a printing station, a takeup roller and the transport apparatus (see Japanese Unexamined Patent Publication No. 2014-24266 ( FIG. 1 ), for example).
  • the above transport apparatus includes a first drive roller, a second drive roller, a third drive roller, and a fourth drive roller.
  • the first drive roller is disposed downstream of the paper feeder, which supplies elongate printing paper, and has a nip roller for feeding the printing paper from the paper feeder.
  • the second drive roller has a nip roller for feeding the printing paper sent by the first drive roller into a printing area directly under the printing station.
  • the third drive roller also called a heat roller
  • the fourth drive roller has a nip roller for sending the printing paper dried by the third drive roller on to the takeup roller.
  • the transport apparatus further includes a first tension sensor disposed downstream of the first drive roller for detecting the tension of the printing paper sent from the first drive roller, a second tension sensor disposed downstream of the second drive roller and upstream of the printing station for detecting the tension of the printing paper in a position upstream of the printing station, and a third tension sensor disposed upstream of the fourth drive roller for detecting the tension in a position upstream of the fourth drive roller.
  • the transport apparatus of such construction employs a transport control method which, while driving the second drive roller at a constant transport speed, controls transport of the printing paper by operating the other drive rollers. Specifically, the first drive roller is operated so that the first tension sensor will attain a target value. The third drive roller is operated so that the second tension sensor will attain the target value. Further, the fourth drive roller is operated so that the third tension sensor will attain the target value. Note that the fourth drive roller is made to reflect speed variations of the third drive roller operated in accordance with the second tension sensor, thereby to reflect tension variations occurring in the printing area.
  • PID Proportional Integral Differential
  • This invention has been made having regard to the state of the art noted above, and its object is to provide a transport control method, a transport apparatus, and a printing apparatus which can inhibit transport irregularities, while suppressing tension variations at the time of acceleration, by rendering a gain variable according to a stability level of tension control.
  • a transport control method for use in transporting a medium in a predetermined direction by an upstream drive roller disposed in an upstream position in a transport direction of the medium, and a downstream drive roller disposed in a downstream position in the transport direction, to operate the downstream drive roller by using PID control based on a detection value of a tension sensor disposed downstream in the predetermined direction of the upstream drive roller and upstream of the downstream drive roller for detecting tension of the medium, the transport control method comprising a stable state determining step for determining, at time of the operation, whether a difference between the detection value of the tension sensor and a target value is within a stable width to make a stable state which maintains a stability time; and a gain decreasing step for decreasing a gain of the PID control to be less than an initial value when the difference is determined to be in the stable state.
  • the gain decreasing step decreases the gain of PID control to be less than the initial value. Therefore, when tension control is not stable such as at a time of acceleration, PID control is carried out with the gain at the initial value. Only when tension control is stable, PID control is carried out with sensitivity lowered by a small gain. As a result, when tension control is unstable as at the time of acceleration, for example, the control amount becomes large. The control amount becomes small when tension control is stable as in a constant speed state. Thus, transport irregularities of the medium can be inhibited while inhibiting tension variations at the time of acceleration.
  • an initial value setting step is executed to set the gain to the initial value when the upstream drive roller starts to be driven from a stopped state, and when the upstream drive roller starts to be decelerated toward the stopped state.
  • the tension is unstable at times of acceleration and deceleration.
  • the control amount is increased to be able to inhibit tension variations at the times of acceleration and deceleration.
  • a gain increasing step is executed to increase the gain when, after the gain decreasing step, the difference is determined to have deviated from the stable width, or although within the stable width, is in a nonstable state incapable of maintaining the stability time.
  • the gain is enlarged to increase the control amount at the time of nonstable state. This can stabilize tension even at times of large tension variations.
  • each of the stable state determining step and the gain decreasing step has the stable width in at least two types.
  • the gain decreasing step has a minimum gain set as a lower limit in decreasing the gain to be less than the initial value.
  • the gain increasing step has a maximum gain set as an upper limit in increasing the gain.
  • the gain is a proportional gain.
  • control In transport control of an elongate printing medium, the control can be performed well only by adjusting the proportional gain.
  • a transport apparatus for transporting a medium in a predetermined direction, comprising an upstream drive roller disposed in an upstream position in a transport direction of the medium; a downstream drive roller disposed in a downstream position in the transport direction; a tension sensor disposed downstream in the predetermined direction of the upstream drive roller, and upstream of the downstream drive roller, for detecting tension of the medium; a drive control unit for operating the downstream drive roller by using PID control based on a detection value of the tension sensor; a stable state determining unit for determining, at time of the operation, whether a difference between the detection value of the tension sensor and a target value is within a stable width to make a stable state which maintains a stability time; and a gain adjusting unit for decreasing a gain of the PID control to be less than an initial value when the stable state determining unit has determined that the difference is in the stable state.
  • the stable state determining unit determines whether or not the difference between the detection value of the tension sensor and the target value is in a stable width to make a stable state which maintains a stability time.
  • the gain adjusting unit makes the gain of PID control smaller than an initial value. Therefore, when tension control is not stable such as at a time of acceleration, PID control is carried out with the gain at the initial value. Only when tension control is stable, PID control is carried out with sensitivity lowered by a small gain. As a result, when tension control is unstable as at the time of acceleration, for example, the control amount becomes large. The control amount becomes small when tension control is stable as in a constant speed state. Thus, transport irregularities of the medium can be inhibited while inhibiting tension variations at the time of acceleration.
  • a printing apparatus for performing printing while transporting an elongate printing medium in a predetermined direction, comprising a printing station for printing on the printing medium in a printing area disposed along a transport path of the printing medium; an upstream drive roller disposed upstream of the printing area; a downstream drive roller disposed downstream of the printing area; a tension sensor disposed downstream in the predetermined direction of the upstream drive roller, and upstream of the printing area, for detecting tension of the printing medium; a drive control unit for operating the downstream drive roller based on a detection value of the tension sensor and by using PID control; a stable state determining unit for determining, at time of the operation, whether a difference between the detection value of the tension sensor and a target value is within a stable width to make a stable state which maintains a stability time; and a gain adjusting unit for decreasing a gain of the PID control to be less than an initial value when the stable state determining unit has determined that the difference is in the stable state.
  • the stable state determining unit determines whether or not the difference between the detection value of the tension sensor and the target value is in a stable width to make a stable state which maintains a stability time.
  • the gain adjusting unit makes the gain of PID control smaller than an initial value. Therefore, when tension control is not stable such as at a time of acceleration, PID control is carried out with the gain at the initial value. Only when tension control is stable, PID control is carried out with sensitivity lowered by a small gain.
  • tension control is unstable as at the time of acceleration, for example, the control amount becomes large. The control amount becomes small when tension control is stable as in a constant speed state.
  • transport irregularities of the printing medium can be inhibited while inhibiting tension variations at the time of acceleration. As a result, the quality of printing on the printing medium by the printing station can be improved.
  • FIG. 1 is a schematic view showing an entire inkjet printing system having a transport apparatus according to an embodiment
  • FIG. 2 is a schematic view showing a control relationship of a first to a fourth drive rollers
  • FIG. 3 is a graph showing a relationship between a command value to the second drive roller, gain, and tension as matched with transport distances of web paper WP;
  • FIG. 4 is a flow chart showing an example of control
  • FIG. 5 is a flow chart showing the example of control
  • FIG. 6 is a graph showing variations in tension in the inkjet printing system according to the embodiment.
  • FIG. 7 is a graph showing variations in command value in the inkjet printing system according to the embodiment.
  • FIG. 8 is a graph showing variations in tension with a gain set to 100% in an inkjet printing system according to a conventional example
  • FIG. 9 is a graph showing variations in command value with the gain set to 100% in the inkjet printing system according to the conventional example.
  • FIG. 10 is a graph showing variations in tension with the gain set to 30% in the inkjet printing system according to the conventional example.
  • FIG. 11 is a graph showing variations in command value with the gain set to 30% in the inkjet printing system according to the conventional example.
  • FIG. 1 is a schematic view showing an entire inkjet printing system having a transport apparatus according to this embodiment.
  • An inkjet printing system 1 includes an inkjet printing apparatus 3 , a paper feeder 5 and a takeup roller 7 .
  • the inkjet printing apparatus 3 performs printing on elongate web paper WP.
  • the paper feeder 5 holds a roll of web paper WP to be rotatable about a horizontal axis, and unwinds the web paper WP from the roll of web paper WP to feed it to the inkjet printing apparatus 3 .
  • the takeup roller 7 winds up the web paper WP printed by the inkjet printing apparatus 3 about a horizontal axis.
  • the paper feeder 5 is disposed upstream of the inkjet printing apparatus 3 while the takeup roller 7 is disposed downstream of the inkjet printing apparatus 3 .
  • the inkjet printing apparatus 3 corresponds to the “printing apparatus” in this invention.
  • the web paper WP corresponds to the “printing medium” and the “medium” in this invention.
  • the inkjet printing apparatus 3 includes a first drive roller M 1 in an upstream position thereof for taking in the web paper WP from the paper feeder 5 .
  • the web paper WP unwound from the paper feeder 5 by the first drive roller M 1 is transported downstream toward the takeup roller 7 along a plurality of rotatable transport rollers 11 .
  • An edge position controller 15 is disposed downstream of the first drive roller M 1 . When the web paper WP wanders off in directions perpendicular to a transport direction, the edge position controller 15 will automatically adjust and control the web paper WP to be transported to a right position.
  • a second drive roller M 2 is disposed downstream of the edge position controller 15 .
  • the web paper WP fed downstream by the second drive roller M 2 has the transport direction changed by a transport roller 11 disposed downstream of the second drive roller M 2 , to advance along a transport path to a printing area PA where printing is done.
  • This transport roller 11 has a rotary encoder 13 mounted thereon.
  • the printing area PA has a plurality of transport rollers 11 arranged along the transport path of the web paper WP.
  • a printing station 19 is disposed above the printing area PA.
  • the printing station 19 in this embodiment includes four inkjet heads 19 a - 19 d, for example.
  • the inkjet head 19 a in the most upstream position for example, dispenses ink droplets of black (K), the next inkjet head 19 b ink droplets of cyan (C), the next inkjet head 19 c ink droplets of magenta (M), and the next inkjet head 19 d ink droplets of yellow (Y).
  • the inkjet heads 19 a - 19 d are arranged separately at predetermined intervals in the transport direction.
  • the web paper WP printed in the printing area PA has the transport direction changed by a downstream transport roller 11 .
  • a third drive roller M 3 is disposed ahead.
  • the third drive roller M 3 winds the web paper WP at a large winding angle, and contacts the web paper WP to dry the ink droplets on the web paper WP.
  • This third drive roller M 3 has a built-in heater, and is also called a heat drum.
  • the web paper WP dried by the third drive roller M 3 is sent by a fourth drive roller M 4 to the takeup roller 7 , while having its direction changed by a plurality of transport rollers 11 .
  • An inspecting unit 23 is disposed upstream of the fourth drive roller M 4 .
  • the inspecting unit 23 inspects the web paper WP printed at the printing station 19 .
  • the takeup roller 7 takes up in a roll form the web paper WP inspected by the inspecting unit 23 .
  • a carrying force to the web paper WP is applied by the nip roller 25 pinching the web paper WP with each drive roller.
  • the pressing force of each nip roller 25 is applied by an air cylinder (not shown), for example.
  • the nip rollers 25 are formed of an elastic material such as rubber, for example.
  • a first tension sensor TP 1 is disposed downstream of the first drive roller M 1 and upstream of the edge position controller 15 .
  • a second tension sensor TP 2 is disposed downstream of the second drive roller M 2 and upstream of the printing area PA.
  • a third tension sensor TP 3 is disposed downstream of the third drive roller M 3 and upstream of the fourth drive roller M 4 .
  • the first to third tension sensors TP 1 -TP 3 successively detect current tension applied to the web paper WP, and output detection values of the tension.
  • the inkjet printing apparatus 3 , paper feeder 5 and takeup roller 7 are operable under overall control of a main controller 49 .
  • the main controller 49 includes a control unit 51 and a storage unit 57 .
  • the control unit 51 is constructed of a CPU and other components.
  • the control unit 51 upon instructions by the operator to start printing, controls transportation of the web paper WP by giving the second drive roller M 2 a command value indicating a transport speed, and giving the first drive motor M 1 , third drive motor M 3 and fourth drive motor M 4 control amounts based on PID control as described in detail hereinafter.
  • the control is carried out with reference to the command value given to the second drive roller M 2 , to realize a printing speed provided by the transport speed at the time of printing which meets printing conditions set beforehand by the operator.
  • the control unit 51 determines the transport speed and transport distances of the web paper WP based on output signals of the rotary encoder 13 .
  • the printing conditions are conditions relating to print quality, such as the transport speed of the web paper WP and each target value of tension in each part applied to the web paper WP, for example.
  • the storage unit 57 stores beforehand two types of stable width, a stability time, a target value of tension, an initial value of gain, a decrease amount of gain, an increase amount of gain, two types of minimum gain, and a maximum gain to be described hereinafter.
  • FIG. 2 is a schematic view showing a control relationship of the first to fourth drive rollers.
  • the control unit 51 carries out PID control based on a difference between a target value of tension to be applied to the web paper W in the location of the first tension sensor TP 1 and a detection value of the first tension sensor TP 1 , and gives a control amount to the first drive roller M 1 to make the detection value equal to the target value.
  • the control unit 51 carries out PID control based on a difference between a target value of tension to be applied to the web paper W in the location of the second tension sensor TP 2 and a detection value of the second tension sensor TP 2 , and gives a control amount to the third drive roller M 3 to make the detection value equal to the target value.
  • control unit 51 carries out PID control based on a difference between a target value of tension to be applied to the web paper WP in the location of the third tension sensor TP 3 and a detection value of the third tension sensor TP 3 , and gives a control amount to the fourth drive roller M 4 to make the detection value equal to the target value. Further, the control unit 51 preferably performs control by adding to the above control amount for the fourth drive roller M 4 an adjustment value based on an amount of change in the rotating speed of the third drive roller M 3 .
  • the second drive roller M 2 described above corresponds to the “upstream drive roller” in this invention.
  • the third drive roller M 3 corresponds to the “downstream drive roller” in this invention.
  • the second tension sensor TP 2 described above corresponds to the “first tension sensor” in this invention.
  • the above control unit 51 carries out PID control based on differences between detection values and target values, and for this purpose the initial value is set to 100%.
  • control is carried out based on only PI of PID control, and the gain adjusted when the state is determined stable is only proportional gain (P) as described hereinafter.
  • control unit 51 described above corresponds to the “drive control unit”, “stable state determining unit” and “gain adjusting unit” in this invention.
  • FIG. 3 is a graph showing a relationship between the command value to the second drive roller M 2 , gain and tension as matched with transport distance of the web paper WP.
  • the control of the command value to the second drive roller M 2 is a control for making a converted speed based on the above rotary encoder 13 constant.
  • the command value to the second drive roller M 2 is therefore zero for distance zero (which corresponds also to time), which command value provides printing speed SP at distance d 1 .
  • the command value given begins deceleration from the printing speed SP at distance d 18 where the printing ends, and reduces the transport speed to zero at distance d 19 .
  • the control amounts to the first drive roller M 1 , third drive roller M 3 , and fourth drive roller M 4 vary as shown in a vertically oscillating dotted line in the graph of the command value to the second drive roller M 2 , for example.
  • the control unit 51 outputs the command value according to a difference between each of the detection values of tension by the first to third tension sensors TP 1 -TP 3 and the target value, and the proportional gain.
  • the control unit 51 determines the differences, it is preferred to make the detection values of tension into moving average deviations. This can suppress disturbance of the control caused by temporary variations of tension due to the influence of noise or external factors.
  • the initial value of gain provides a gain at the time PID control is started, a gain at the time of increasing transport speed from stopped state to printing speed, and a gain the time of stopping transport speed from printing speed.
  • the decrease amount of gain G 1 provides an amount of gain subtracted from a current gain when stable state is determined.
  • the increase amount of gain G 2 provides an amount of gain added to a current gain when a nonstable state is determined.
  • Minimum gain Gmin 1 provides a lower limit to a gain resulting from a subtraction made when a stable state is determined in stable width A.
  • Minimum gain Gmin 2 provides a lower limit to a gain resulting from a subtraction made when a stable state is determined in stable width B.
  • Maximum gain Gmax provides an upper limit to a gain resulting from an addition.
  • the gain may be decreased by a decrease amount of gain G 2 having a larger value than the decrease amount of gain G 1 when the stable state is determined based on stable width A. Since the gain can thereby be made small quickly, tension control can be performed with increased stability when the stable state is continued.
  • the tension and gain in FIG. 3 may represent any combination of the first tension sensor TP 1 and first drive roller M 1 , the second tension sensor TP 2 and third drive roller M 3 , or the third tension sensor TP 3 and fourth drive roller M 4 .
  • the second drive roller M 2 , third drive roller M 3 , second tension sensor TP 2 , and control unit 51 correspond to the “transport apparatus” in this invention.
  • FIGS. 4 and 5 are a flow chart showing an example of control.
  • the initial value need not necessarily be 100%, but should preferably be a maximum value of gains to be adjusted.
  • the control unit 51 repeatedly checks whether acceleration is completed, and moves to the next process in step S 3 upon completion of acceleration.
  • the control unit 51 branches the process based on whether deceleration is started or not.
  • Difference ⁇ ts between the detection value of tension and the target value is calculated.
  • the detection values of tension at the time of calculating difference ⁇ ts preferably, are moving average deviations for the reason noted hereinbefore.
  • Steps S 6 -S 9 carry out processes for lowering the gain when difference ⁇ ts of tension is within the stable width A to maintain a stability time ST.
  • step S 7 Checking is made whether or not difference ⁇ ts is within the stable width A and this state maintains the stability time ST, and the process branches according to the result.
  • difference ⁇ ts is within the stable width A to make a stable state which maintains the stability time ST, the process moves to step S 7 . Otherwise it is a nonstable state, and the process moves to step S 2 .
  • step S 6 When step S 6 indicates a stable state in which difference ⁇ ts is within the stable width A and this state maintains the stability time ST, the gain decrease amount G 1 is subtracted from a current gain to make a new gain.
  • the gain resulting from the subtraction is compared with the minimum gain Gmin 1 , and the process branches according to a result of the comparison.
  • the process branches to step S 2 .
  • the process moves to step S 9 .
  • the gain resulting from the subtraction is smaller than minimum gain Gmin 1 , the gain is set to minimum gain Gmin 1 and the gain is fixed irrespective of the arithmetic result. This can avoid an excessively small gain lowering sensitivity too much, which would cause an inconvenience in tension adjustment.
  • Steps S 10 -S 13 carry out processes for lowering the gain when difference ⁇ ts of tension is within the stable width B to maintain a stability time ST.
  • a gain decrease amount G 1 a larger than the gain decrease amount G 1 may be used to increase the decrease amount in the case of stable width A.
  • step S 11 the process moves to step S 14 .
  • step S 10 When step S 10 indicates a stable state in which difference ⁇ ts is within the stable width B and this state maintains the stability time ST, the gain decrease amount G 1 is subtracted from a current gain to make a new gain.
  • the gain resulting from the subtraction is compared with the minimum gain Gmin 2 , and the process branches according to a result of the comparison.
  • the process branches to step S 2 .
  • the process moves to step S 13 .
  • minimum gain Gmin 2 When the gain resulting from the subtraction is smaller than minimum gain Gmin 2 , the gain is set to minimum gain Gmin 2 and the gain is fixed irrespective of the arithmetic result. This can avoid an excessively small gain lowering sensitivity too much, which would cause an inconvenience in tension adjustment.
  • minimum gain Gmin 2 >minimum gain Gmin 1 The reason for minimum gain Gmin 2 >minimum gain Gmin 1 is that the stable width B is wider than the stable width A and has larger tension variations than the stable width A, and therefore preferably has a larger gain than in the stable state within the stable width A.
  • Steps S 14 -S 17 confirm a shift of difference ⁇ ts from stable width A to stable width B. In other words, these steps check whether or not the tension control has been disturbed.
  • step S 15 Checking is made whether or not difference ⁇ ts has shifted from stable width A to stable width B or has shifted outside stable width B, and the process branches according to the result. When it has shifted, the process moves to step S 15 . Otherwise the process moves to step S 18 .
  • the gain increase amount G 2 is added to the current gain.
  • the gain resulting from the addition is compared with the maximum gain Gmax, and the process branches according to a result of the comparison.
  • the process branches to step S 17 .
  • the process moves to step S 2 .
  • the gain is fixed to the maximum gain Gmax. Setting the maximum gain Gmax as an upper limit can avoid an excessively large gain raising sensitivity too much, which would cause an inconvenience in tension adjustment.
  • Steps S 18 -S 21 confirm a shift of difference ⁇ ts beyond stable width B. In other words, these steps check whether or not the tension control has been further disturbed.
  • step S 19 the process moves to step S 19 . Otherwise the process moves to step S 2 .
  • the gain increase amount G 2 is added to the current gain.
  • the gain resulting from the addition is compared with the maximum gain Gmax, and the process branches according to a result of the comparison.
  • the process branches to step S 21 .
  • the process moves to step S 2 .
  • the gain is fixed to the maximum gain Gmax.
  • the control unit 51 when operating the first drive roller M 1 , third drive roller M 3 , and fourth drive roller M 4 by PID control, determines whether or not differences ⁇ ts between the detection values of the first-third tension sensors TP 1 -TP 3 and the target value are in the stable width A or B to make a stable state which maintains a stability time ST.
  • the gain of PID control is made smaller than an initial value. Therefore, when tension control is not stable such as at a time of acceleration, PID control is carried out with the gain at the initial value. Only when tension control is stable, PID control is carried out with sensitivity lowered by a small gain. As a result, when tension control is unstable as at the time of acceleration, for example, the control amount becomes large.
  • the control amount becomes small when tension control is stable as in a constant speed state.
  • transport irregularities of the web paper WP can be inhibited while inhibiting tension variations at the time of acceleration.
  • the quality of printing on the web paper WP by the printing station 19 can be improved.
  • the gain is set to the initial value when starting drive from a stopped state to the printing speed and when starting deceleration from the printing speed to a stopped state. This can inhibit tension variations at the times of acceleration and deceleration. Further, the gain is enlarged to increase the control amount at the time of nonstable state. This can stabilize tension even at times of large tension variations.
  • FIG. 6 is a graph showing variations in tension in the inkjet printing system according to the embodiment.
  • FIG. 7 is a graph showing variations in the command value in the inkjet printing system according to the embodiment.
  • FIG. 8 is a graph showing variations in tension with a gain set to 100% in an inkjet printing system according to the conventional example.
  • FIG. 9 is a graph showing variations in the command value with the gain set to 100% in the inkjet printing system according to the conventional example.
  • FIG. 10 is a graph showing variations in tension with the gain set to 30% in the inkjet printing system according to the conventional example.
  • FIG. 11 is a graph showing variations in the command value with the gain set to 30% in the inkjet printing system according to the conventional example.
  • the gain is reduced a plurality of times when a stable state is indicated.
  • the gain may be reduced only once.
  • the foregoing embodiment provides two types of stable width.
  • This invention is not limited to this.
  • the stable width may be provided in one type, or in three or more types.

Landscapes

  • Controlling Rewinding, Feeding, Winding, Or Abnormalities Of Webs (AREA)
  • Feedback Control In General (AREA)
US15/899,824 2017-03-21 2018-02-20 Transport control method, a transport apparatus, and a printing apparatus Abandoned US20180273330A1 (en)

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JP2017054419A JP6913488B2 (ja) 2017-03-21 2017-03-21 搬送制御方法及び搬送装置並びに印刷装置
JP2017-054419 2017-03-21

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Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US10338539B1 (en) * 2018-02-19 2019-07-02 Hamilton Sundstrand Corporation Actuator control system with transient reduction after redundancy level changes
US10377598B2 (en) * 2017-02-17 2019-08-13 Eaton Intelligent Power Limited Dynamic performance and active damping methods in web winder tension control systems
US11148412B2 (en) * 2016-11-14 2021-10-19 Asahi Kasei Kabushiki Kaisha Roll-to-roll printing apparatus
WO2022223156A1 (de) * 2021-04-23 2022-10-27 Thyssenkrupp Steel Europe Ag Beschichtungsanlage zum beschichten eines bands und verfahren zum beschichten eines bands
US11884059B2 (en) 2019-09-27 2024-01-30 SCREEN Holdings Co., Ltd. Printing device

Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US11148412B2 (en) * 2016-11-14 2021-10-19 Asahi Kasei Kabushiki Kaisha Roll-to-roll printing apparatus
US10377598B2 (en) * 2017-02-17 2019-08-13 Eaton Intelligent Power Limited Dynamic performance and active damping methods in web winder tension control systems
US10338539B1 (en) * 2018-02-19 2019-07-02 Hamilton Sundstrand Corporation Actuator control system with transient reduction after redundancy level changes
US11884059B2 (en) 2019-09-27 2024-01-30 SCREEN Holdings Co., Ltd. Printing device
WO2022223156A1 (de) * 2021-04-23 2022-10-27 Thyssenkrupp Steel Europe Ag Beschichtungsanlage zum beschichten eines bands und verfahren zum beschichten eines bands

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JP6913488B2 (ja) 2021-08-04

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