WO2021065103A1

WO2021065103A1 - Method for adjusting tension in printing device and printing device

Info

Publication number: WO2021065103A1
Application number: PCT/JP2020/024380
Authority: WO
Inventors: 修森園; 浩明岸田; 昌二柿本
Original assignee: 株式会社Ｓｃｒｅｅｎホールディングス
Priority date: 2019-09-30
Filing date: 2020-06-22
Publication date: 2021-04-08
Also published as: JP7278918B2; JP2021054581A

Abstract

In the present invention, a step for restoring the tension in a continuous paper WP to a target value Ln is changed in accordance with the value of the tension in the continuous paper WP during a state in which conveyance of the continuous paper WP is stopped. That is to say, if the tension in the continuous paper WP is at or above a reference value Bo, the tension in the continuous paper WP is restored by means of drive from a drive roller M4, etc., without actuating a driven roller movement part 53. Meanwhile, if the tension in the continuous paper WP is less than the reference value Bo, the driven roller movement part 53 is actuated and a nip state in the continuous paper WP is released so that slack in the continuous feed paper WP, which had accumulated in a downstream region Wb, is distributed. Then, after a prescribed amount of time has passed since releasing the nip, the nip state is reinstated, and the continuous paper WP is conveyed in a reverse direction J2.

Description

Tension adjustment method in printing equipment and printing equipment

The present invention relates to a printing apparatus using an inkjet printing apparatus as an example, a method of adjusting the tension of a printing medium such as long paper or a long film, and a printing apparatus using the method.

Conventionally, as a printing device for printing a long print medium, a supply unit, a printing unit that prints on the print medium, a collection unit, and a long print medium are conveyed in a predetermined direction. Those provided with a transfer device have been proposed (for example, Patent Document 1).

The transfer device is arranged on the downstream side of the supply unit that supplies a long print medium, and has been fed by a first drive roller having a nip roller that feeds out printing paper from the supply unit, and the first drive roller. A second drive roller provided with a nip roller that feeds the print medium into the printing unit, a third drive roller (also called a heat roller) that winds the print medium at a large winding angle to dry it, and feeds the print medium. It is provided with a fourth drive roller provided with a nip roller that sends the print medium dried by the drive roller 3 to the collection unit.

Further, the transfer device includes a plurality of transfer rollers arranged at predetermined positions. The print medium is fed along a predetermined trajectory such that the respective transport rollers come into contact with each other. That is, the nip roller and the transport roller are configured to apply a predetermined amount of tension to the print medium.

JP-A-2017-109872

However, in the case of the conventional example having such a configuration, there are the following problems. That is, in a printing apparatus having a conventional configuration, if the transfer of the print medium is stopped for various reasons and then the transfer is restarted, the transfer error that the print medium cannot be sent normally occurs frequently, so that the printing efficiency is lowered. There is concern about the problem. In addition, the print medium may be broken when the transport is stopped and restarted.

The present invention has been made in view of such circumstances, and is a tension adjusting method capable of more preferably eliminating the slack generated in a long print medium and recovering the tension of the print medium. , And a printing apparatus comprising the method.

As a result of examination by the present inventors in order to solve the above problem, it became clear that the cause of the above situation is as follows. That is, in the printing apparatus having the conventional configuration, since the printing medium is dried by the third drive roller, the print medium is wound at a large winding angle. Therefore, the third drive roller has a larger diameter and is larger than the other drive rollers. The inertia is also large. Therefore, when the printing apparatus is stopped, the relatively small rollers such as the first drive roller have a small inertia and therefore stop quickly. On the other hand, the third drive roller having a large inertia takes time to stop.

As a result of such a difference in rotational speed of the drive rollers when the printing apparatus is stopped, the tension of the print medium is lowered, especially in the downstream region of the third drive roller, and the print medium is frequently loosened. Since the print quality deteriorates when the print medium is loosened, it is necessary to remove the looseness of the print medium to recover the tension. Since it takes time to manually recover the tension, the operating efficiency of the printing apparatus is lowered.

In particular, in the case of an emergency stop of a printing device different from the normal stop procedure, the difference in rotation speed of the drive rollers at the time of stop becomes larger, so that the slack generated in the print medium becomes larger. Then, the print medium may buckle due to a large slack, and the buckled print medium may be caught in the rollers. If the buckled print medium is caught in the roller, there is a concern that the print medium may be broken when the printing apparatus is returned from the stop. When the print medium is broken, it takes a lot of time and labor to restore the print medium so that it has a long shape along a predetermined locus. As a result, the operating efficiency of the printing apparatus is further reduced.

The present invention has the following configuration in order to achieve such an object.
That is, the tension adjusting method according to the present invention includes a feeding unit that feeds out a long print medium, a winding unit that winds up the printing medium, a printing unit that prints on the printing medium, and the feeding unit. It has a main roller disposed between the take-up portion and a first drive roller and a first driven roller having a smaller inertia than the main roller, and the take-up portion and the main roller A second nip roller having a first nip roller disposed between them, a second drive roller and a second driven roller, and arranged between the delivery portion and the main roller, and the said In a printing apparatus including a first tension sensor that detects the tension of the printing medium between the main roller and the first nip roller, in a direction of conveying the printing medium when printing by the printing unit. A normal transfer step of transporting the print medium from the feed section to the take-up section by driving each of the main roller, the first drive roller, and the second drive roller in a certain transport direction. The first tension detection step of detecting the output of the first tension sensor when the normal transfer process is stopped and the recovery process different depending on the value of the output detected in the first tension detection step are performed. The print medium is provided with a tension recovery step of recovering the tension of the print medium to the tension value in the normal transfer step, and the tension recovery step is such that the output detected in the first tension detection step is equal to or higher than a predetermined reference value. In some cases, the operation of driving the first drive roller in the transport direction and the direction opposite to the transport direction of the second drive roller while the print medium is nipped by the first nip roller. When the output detected in the first recovery step and the first tension detection step, which executes at least one of the operations of driving the print medium, is smaller than the reference value, the nip of the print medium is released by the first nip roller. After the nip release step, the nip recovery step of niping the print medium by the first nip roller after a lapse of a predetermined time from the nip release step, and the nip recovery step, the second drive roller is moved in the opposite direction to the transport direction. It is characterized by including a driving process for driving in the direction of the above and a second recovery process including.

[Action / Effect] According to the tension adjusting method according to the present invention, after stopping the normal transfer process, the tension of the print medium can be automatically restored to the value of the tension in the normal transfer process by the tension recovery step. Therefore, the operating efficiency of the printing device can be improved. Further, the tension recovery step recovers the tension of the print medium to the tension value in the normal transfer step by performing different recovery processes according to the output value detected in the first tension detection step. Therefore, it is possible to execute an appropriate recovery process according to the pattern in which the normal transfer process is stopped.

That is, if the degree of tension drop of the print medium is small when stopped, the first recovery step without controlling the nip roller is performed. Therefore, it is possible to avoid a situation in which the operating efficiency of the printing apparatus is unnecessarily reduced as a result of performing the processing for a long processing time even though the degree of tension reduction of the printing medium is small at the time of stopping. On the other hand, if the degree of tension drop of the print medium is large when stopped, the second recovery step is performed. The second recovery step includes a step of releasing the nip roller and re-execution, and the step disperses and reduces the slack of the print medium. Therefore, it is possible to avoid a situation in which a transport error occurs in the print medium after resuming printing as a result of performing a process in which the tension recovery efficiency is small even though the degree of tension drop of the print medium is large at the time of stopping.

Further, in the above-described invention, the second recovery step includes a second tension detection step for detecting the output of the first tension sensor after the nip recovery step, and the output detected in the second tension detection step. Is smaller than the reference value, the tension of the print medium is recovered by executing the drive step, and when the output detected in the second tension detection step is equal to or more than the reference value, the drive step is replaced. It is preferable to recover the tension of the print medium by executing the first recovery step.

[Action / Effect] According to the tension adjusting method according to the present invention, the second recovery step is also controlled so as to perform different recovery processes according to the output value detected in the second tension detection step. Therefore, an appropriate recovery process can be executed according to the degree of slack generated in the print medium.

Further, in the above-described invention, in the drive step, a distance storage step of storing the distance of the print medium conveyed in the reverse direction as the reverse transfer distance by driving the second drive roller in the reverse direction is further performed. After the tension recovery step, it is preferable to feed the print medium in the forward direction by the amount of the reverse transport distance and then restart the normal transport step.

[Action / Effect] According to the tension adjusting method according to the present invention, after the tension recovery step, the print medium is fed forward by the distance that the print medium is conveyed in the reverse direction, and then the normal transfer process is restarted. .. In this case, the position of the print medium at the time when the normal transfer process is restarted is matched with the position of the print medium at the time when the normal transfer process is stopped. Therefore, when the normal transfer process is restarted and the printing process is performed, it is possible to avoid a situation in which the information to be printed deviates from the originally planned location.

Further, in the above-described invention, it is preferable to drive the second drive roller in the reverse direction and drive the first drive roller in the forward direction in the drive step.

[Action / Effect] According to the tension adjusting method according to the present invention, in the driving process, the second driving roller is driven in the opposite direction and the first driving roller is driven in the forward direction. That is, since the print medium is conveyed so as to be pulled in both directions, the tension of the print medium can be recovered in a shorter time.

Further, in the above-described invention, the printing apparatus includes a second tension sensor that detects the tension of the printing medium between the main roller and the second nip roller, and the tension recovery step is the driving. After the step, it is preferable to include a third tension detection step of detecting the output of the second tension sensor.

[Action / Effect] According to the tension adjusting method according to the present invention, the tension of the print medium between the main roller and the second nip roller is detected by the second tension sensor. In this case, the tension recovery step can be executed while detecting the tension in a wider range. Therefore, it is possible to avoid a situation in which a transfer error of the print medium occurs when the normal transfer process is restarted because the tension of the print medium between the main roller and the second nip roller cannot be fully recovered.

Further, in the above-described invention, the printing apparatus includes a dancer roller disposed between the take-up portion and the first nip roller, and the nip is eliminated by the nip release step. It is preferable to include a slack eliminating step of relieving at least a part of the slack of the printing medium between the winding portion and the main roller with the dancer roller.

[Action / Effect] According to the tension adjusting method according to the present invention, by performing the slack eliminating step in a state where the nip is eliminated, at least a part of the slack of the print medium between the take-up portion and the main roller is performed. Is solved with a dancer roller. Therefore, the slack in the print medium can be more preferably eliminated in the second recovery step, so that the tension recovery efficiency can be improved.

In order to achieve such an object, the present invention may have the following configuration.
That is, the printing apparatus according to the present invention includes a feeding unit that feeds out a long print medium, a winding unit that winds up the printing medium, a printing unit that prints on the printing medium, and the feeding unit. It has a main roller disposed between the take-up portion, a first drive roller and a first driven roller having a smaller inertia than the main roller, and is between the take-up portion and the main roller. A second nip roller which has a first nip roller, a second drive roller, and a second driven roller and is arranged between the delivery portion and the main roller, and the main The main tension sensor that detects the tension of the print medium between the roller and the first nip roller, and the main in the transfer direction that is the direction in which the print medium is conveyed when printing is performed by the printing unit. When the normal transport process of transporting the print medium from the feeding portion to the winding portion by driving each of the roller, the first driving roller, and the second driving roller is stopped, the first By detecting the output of the tension sensor of the above and performing different processing according to the output value of the first tension sensor, the tension of the printing medium is restored to the tension value in the normal conveying process. The control unit includes a control unit that controls the transfer of the print medium, and when the output of the first tension sensor is equal to or higher than a predetermined reference value, the print medium is nipated by the first nip roller. Control is performed to execute at least one of the operation of driving the first drive roller in the transport direction and the operation of driving the second drive roller in the direction opposite to the transport direction, and the first tension is performed. When the output of the sensor is smaller than the reference value, the nip of the print medium is released by the first nip roller, and the print medium is niped by the first nip roller after a lapse of a predetermined time from the release of the nip of the print medium. The second drive roller is controlled to be driven in a direction opposite to the transport direction while the print medium is nipped.

With this configuration, after the normal transfer process is stopped, the tension of the printing medium can be automatically restored to the value of the tension in the normal transfer process, so that the operating efficiency of the printing apparatus can be improved. Further, the control unit recovers the tension of the print medium to the tension value in the normal transfer process by performing different recovery processes according to the output value detected in the first tension detection step. Therefore, it is possible to execute an appropriate recovery process according to the pattern in which the normal transfer process is stopped.

According to the tension adjusting method and the printing apparatus according to the present invention, after stopping the normal transfer process, the tension of the printing medium can be automatically restored to the value of the tension in the normal transfer process. Therefore, it is possible to improve the operating efficiency of the printing apparatus, and it is possible to avoid a situation such as a transfer error or breakage of the print medium when the transfer of the print medium is stopped and then restarted.

Further, the control unit recovers the tension of the print medium to the tension value in the normal transfer process by performing different recovery processes according to the output value detected in the first tension detection step. That is, since an appropriate recovery process can be executed according to the pattern in which the normal transfer process is stopped, the time required for tension recovery can be shortened, and a transfer error can be more reliably generated when the transfer of the print medium is restarted. Can be prevented.

It is a figure explaining the schematic structure of the printing apparatus which concerns on Example. It is a figure explaining step S1 and step S2 which concerns on Example. (A) is a time chart showing the time-series change of the output value of the tension sensor TP3 when the printing process is started and stopped, and (b) is a schematic diagram showing the state of step S1. c) is a schematic diagram showing a state in which the rotation of the drive roller is gently stopped in step S2, and (d) is a schematic diagram showing a state in which the rotation of the drive roller is suddenly stopped in step S2. .. It is a flowchart explaining the operation process of the printing apparatus which concerns on Example. It is a figure explaining step S4 and step S5 which concerns on Example. (A) is a schematic diagram showing a state before executing the process according to step S4, (b) is a schematic diagram showing a state in which the process according to step S4 is being executed, and (c) is a schematic diagram showing a state in which the process according to step S4 is being executed. It is a schematic diagram which shows the state in. It is a figure explaining step S11 which concerns on Example. (A) is a schematic diagram showing a state before releasing the nip, (b) is a schematic diagram showing a state in which the nip is released, and (c) is a schematic diagram showing a state in which the dancer roller is operated. It is a figure. It is a figure explaining step S12 which concerns on Example. It is a figure explaining step S14 which concerns on Example. (A) is a schematic diagram showing a state before executing the process according to step S14, and (b) is a schematic diagram showing a state in which the process according to step S14 is being executed. It is a figure explaining step S14 which concerns on Example. It is a figure explaining step S16 which concerns on Example. It is a figure explaining the modification of step S4 of an Example.

Hereinafter, examples of the present invention will be described with reference to the drawings. FIG. 1 is a schematic configuration diagram showing the entire printing apparatus according to the embodiment. In this embodiment, the printing apparatus according to the present invention will be described by taking an inkjet printing system as an example.

<Explanation of the overall configuration>
The inkjet printing system 1 according to the embodiment includes an inkjet printing device 3, a paper feeding unit 5, and a paper discharging unit 7. Assuming that the supply side of the continuous paper WP is upstream and the discharge side of the continuous paper WP is downstream, the paper feed unit 5 is arranged on the upstream side of the inkjet printing device 3, and the paper discharge unit 7 is located on the downstream side of the inkjet printing device 3. Have been placed.

The inkjet printing device 3 prints on a long continuous paper WP. The paper feeding unit 5 includes a feeding mechanism 5a and a buffer mechanism 5b. The feeding mechanism 5a includes an original roll on which the continuous paper WP is wound and a bobbin on which the original roll is loaded, and is rotatably held around a horizontal axis. The feeding mechanism 5a unwinds the continuous paper WP and supplies it to the inkjet printing apparatus 3. The buffer mechanism 5b is arranged downstream of the delivery mechanism 5a, and includes a buffer roller 60 and a dancer roller 61. By moving the dancer roller 61 up and down, the tension of the continuous paper WP in the paper feed unit 5 can be adjusted. The feeding mechanism 5a corresponds to the feeding portion in the present invention.

The paper ejection unit 7 includes a winding mechanism 7a and a buffer mechanism 7b. The take-up mechanism 7a includes a bobbin for collecting the continuous paper WP printed by the inkjet printing device 3 around the horizontal axis. The buffer mechanism 7b is arranged on the upstream side of the winding mechanism 7a, and includes a buffer roller 70 and a dancer roller 71. By moving the dancer roller 71 up and down, the tension of the continuous paper WP in the paper ejection unit 7 can be adjusted. The winding mechanism 7a corresponds to the winding portion in the present invention.

The inkjet printing device 3 is provided with a drive roller M1 for taking in continuous paper WP from the paper feed unit 5 on the upstream side. The continuous paper WP unwound from the paper feed unit 5 by the drive roller M1 is conveyed toward the paper discharge unit 7 on the downstream side along the rotatable transfer roller 11 and the like.

An edge position control unit 15 is arranged on the downstream side of the drive roller M1. The edge position control unit 15 automatically adjusts when the continuous paper WP meanders in the direction orthogonal to the conveying direction J1 and controls so that the continuous paper WP is conveyed to the correct position.

A drive roller M2 is arranged on the downstream side of the edge position control unit 15. A transport roller 11 to which the rotary encoder 13 is attached is arranged on the downstream side of the drive roller M2. The continuous paper WP sent to the downstream side by the drive roller M2 is conveyed to the printing area PA by changing the conveying direction by the conveying roller 11.

In the print area PA, a plurality of transfer rollers 11 are arranged along the transfer path of the continuous paper WP. A printing unit 19 is arranged above the printing area PA. The printing unit 19 is composed of four inkjet heads 19a to 19d as an example. For example, the most upstream inkjet head 19a ejects black (K) ink droplets, the next inkjet head 19b ejects cyan (C) ink droplets, and the next inkjet head 19c ejects magenta (M). Inkjet head 19d ejects yellow (Y) ink droplets. The inkjet heads 19a to 19d are arranged apart from each other by a predetermined interval in the transport direction.

The continuous paper WP printed in the print area PA is changed in the transport direction by the transport roller 11 on the downstream side. A drive roller M3 is arranged at that position. The drive roller M3 winds the continuous paper WP at a large winding angle and abuts on the continuous paper WP to dry the ink droplets on the continuous paper WP. The drive roller M3 has a built-in heater and is also called a heat drum.

By winding the continuous paper WP around the drive roller M3 with a large winding angle, the heat of the heater is more efficiently transferred to the continuous paper WP, so that the drying efficiency of the continuous paper WP can be improved. Therefore, the drive roller M3 is composed of a large roller having a larger diameter than the drive rollers M1, M2, and M4. The third drive roller M3 has a larger inertia than the drive rollers M1, M2, and M4. The drive roller M3 corresponds to the main roller in the present invention.

The continuous paper WP dried by the drive roller M3 is sent to the paper ejection unit 7 by the drive roller M4 while being changed in direction by the plurality of transfer rollers 11. An inspection unit 23 is arranged on the upstream side of the drive roller M4. The inspection unit 23 inspects the continuous paper WP printed by the printing unit 19. The paper ejection unit 7 winds up the continuous paper WP inspected by the inspection unit 23 in a roll shape.

The drive roller M1, the drive roller M2, and the drive roller M4 described above are individually rotatably attached with a driven roller N. Specifically, the driven roller N1 is attached to the drive roller M1, and the nip roller 25a is composed of the drive roller M1 and the driven roller N1. A driven roller N2 is attached to the drive roller M2, and the nip roller 25b is composed of the drive roller M2 and the driven roller N2. A driven roller N3 is attached to the drive roller M4, and a nip roller 25c is formed by the drive roller M4 and the driven roller N3. The driven rollers N1 to N3 are made of an elastic body such as rubber as an example.

In the present embodiment, the nip roller 25c arranged downstream of the drive roller M3 corresponds to the first nip roller in the present invention, and the nip roller 25b arranged upstream of the drive roller M2 corresponds to the second nip roller 25b in the present invention. Corresponds to a nip roller.

The driven rollers N1 to N3 are configured to be movable back and forth by the driven roller moving unit 53, which will be described later, and the on / off of the nip of the continuous paper WP by the nip rollers 25a to 25c is controlled by the moving back and forth. As an example, the driven roller N1 moves so as to approach the driving roller M1, so that the nip roller 25a sandwiches the continuous paper WP. That is, the nip by the nip roller 25a is turned on. On the other hand, when the driven roller N1 moves away from the driving roller M1, the nip of the continuous paper WP by the nip roller 25a is released. That is, the nip by the nip roller 25a is turned off.

The conveying force to the continuous paper WP is given by sandwiching the continuous paper WP between each driving roller and each driven roller in the nip rollers 25a to 25c. The pressing force by the driven roller 25 is applied by the driven roller moving unit 53. The nip roller 25 is made of an elastic body such as rubber.

The tension sensor TP1 is arranged on the downstream side of the drive roller M1 and on the upstream side of the edge position control unit 15. Further, the tension sensor TP2 is arranged on the downstream side of the drive roller M2 and on the upstream side of the print area PA, and the tension sensor TP3 is arranged on the downstream side of the drive roller M3 and on the upstream side of the drive roller M4. Has been done. The tension sensors TP1 to TP3 sequentially detect the current tension applied to the continuous paper WP and output it as a tension detection value.

The above-mentioned inkjet printing apparatus 3, the paper feeding unit 5, and the paper discharging unit 7 are collectively controlled by the main control unit 49. The main control unit 49 includes a control unit 51 composed of a CPU and the like. The control unit 51 controls the rotation of the drive rollers M1 to M4 described above, and the drive rollers M1 to M4 are configured to be rotatable in both forward and reverse directions. By rotating the drive rollers M1 to M4 in the forward direction, the continuous paper WP is conveyed in the conveying direction J1. By rotating the drive rollers M1 to M4 in the opposite direction, the continuous paper WP can be conveyed in the direction opposite to the conveying direction J1.

The control by the control unit 51 is performed so that the transfer speed is set according to the printing conditions set in advance by the operator. The control unit 51 determines the transfer speed and the transfer distance based on the output signal of the rotary encoder 13. The printing conditions are conditions related to print quality, such as the transport speed of the continuous paper WP and each target value of tension in each part applied to the continuous paper WP.

The inkjet printing device 3 includes a driven roller moving unit 53 and a notification unit 55. The driven roller moving unit 53 is configured by an air cylinder or the like as an example, and the operation of the driven roller moving unit 53 is controlled by the control unit 51. The driven roller moving unit 53 is connected to each of the driven rollers N1 to N3, and each of the driven rollers N1 to N3 can move forward and backward with respect to the driving rollers M1, M2, and M4 by the operation of the driven roller moving unit 53. It is configured as follows.

The notification unit 55 operates according to the control of the control unit 51. If the tension of the continuous paper WP does not recover to a desired value even after performing the tension adjusting step automatically executed, the notification unit 55 notifies the information that the continuous paper WP has not been recovered by the automatic processing. Examples of the configuration of the notification unit 55 include a buzzer that generates an alarm sound to notify the notification, a lamp that generates light to notify the notification, a display that displays information that the tension is not automatically recovered, and the like. The main control unit 49 further includes a storage unit 57. The storage unit 57 stores in advance a reference value and the like, which will be described later.

Here, with reference to FIG. 2, an outline regarding the start and stop of the printing process in the inkjet printing system 1 according to the embodiment will be described. Note that FIG. 2A is a schematic diagram showing a time-series change in the output value of the tension sensor TP3 when the printing process is started and stopped. Of FIGS. 2 (b) to 2 (d), the upper figure is a diagram schematically showing the configurations of the drive roller M3 upstream and downstream, and the lower figure is the upstream region Wf and the downstream region Wb of the drive roller M3. It is a figure which shows typically the value of the tension (tension) of continuous paper WP in.

In this embodiment, the upstream region Wf corresponds to the region between the drive roller M3 and the nip roller 25b. Further, in this embodiment, the downstream region Wb corresponds to the region between the drive roller M3 and the nip roller 25c.

When the operation of the inkjet printing system 1 is started at time t0, as shown in FIG. 2B, the nip rollers 25a to 25c nip (hold) the continuous paper WP according to the control of the control unit 51, and further, the drive roller M1 ~ M4 rotates in the forward direction. By this control, tension is gradually applied to the continuous paper WP. Then, when the tension applied to the entire continuous paper WP reaches the target value Ln, the transfer of the continuous paper WP and the printing on the continuous paper WP are started at a predetermined time t1.

Then, at time t2, the operation of the inkjet printing system 1 is stopped. At this time, the pattern in which the tension in the downstream region Wb of the drive roller M3 decreases differs depending on the pattern for stopping the operation.

When the urgency is relatively low as the first stop pattern, the transfer and printing of the continuous paper WP are stopped by gradually reducing the rotation speed of each motor that drives the drive rollers M1 to M4. When such a relatively gentle stop is performed, the difference between the inertia (inertia force) in the drive roller M3 and the inertia in the drive roller M4 is relatively small. Therefore, as shown in FIG. 2C, the slack of the continuous paper WP generated in the downstream region Wb is relatively small. Therefore, the output value of the tension sensor TP3, that is, the tension value in the downstream region Wb, decreases relatively slowly as shown by the alternate long and short dash line P1 in FIG. 2A, and becomes a predetermined value F1 from the target value Ln.

The predetermined value F1 is a value higher than the predetermined reference value Bo. The reference value Bo is a value determined by conditions such as the thickness and strength of the continuous paper WP, and is a value that serves as a threshold value for branching the content of the tension adjustment process described later.

When the urgency is relatively high as the second stop pattern, the transfer and printing of the continuous paper WP are stopped by rapidly reducing the rotation speed of each motor for driving the drive rollers M1 to M4 to zero. When such a sudden stop is performed, the difference between the inertia in the drive roller M3 and the inertia in the drive roller M4 is relatively large. That is, even after the drive rollers M1, M2, and M4 having a small inertia are stopped, the drive roller M3 rotates for a relatively long time due to the inertia.

As a result, as shown in FIG. 2D, a relatively large slack is generated with respect to the continuous paper WP in the downstream region Wb. Therefore, the output value of the tension sensor TP3 sharply decreases as shown by the solid line P2 in FIG. 2A, and decreases from the target value Ln to the predetermined value F2. The predetermined value F2 is a value lower than the reference value Bo. As described above, the tension value of the downstream region Wb in the state where the drive rollers M1 to M4 are stopped differs depending on the stop pattern.

After the rotation of the drive rollers M1 to M4 is stopped, the process of adjusting the tension of the continuous paper WP is started at time t3. By the tension adjustment process, the tension of the continuous paper WP is restored from the predetermined value F1 (or F2) to the target value Ln. After the tension recovers to the target value Ln at time t4, the transfer of the continuous paper WP and the printing on the continuous paper WP are restarted at the time t5.

<Explanation of operation>
Here, the operation for adjusting the tension in the inkjet printing system 1 according to the embodiment will be described with reference to FIGS. 3 and 4 to 9 as appropriate. FIG. 3 is a flowchart illustrating the operation of the inkjet printing system 1 according to the embodiment. 4 is a schematic diagram for explaining steps S4 and S5, which will be described later, FIG. 5 is a schematic diagram for explaining step S11, FIG. 6 is a schematic diagram for explaining step S12, and FIGS. 7 and 8 are. FIG. 9 is a schematic diagram for explaining step S14, and FIG. 9 is a schematic diagram for explaining step S16. More specifically, FIG. 4A is a schematic diagram showing a state before executing the process according to step S4, and FIG. 4B is a schematic diagram showing a state in which the process according to step S4 is being executed. (C) is a schematic diagram showing the state in step S5. FIG. 5A is a schematic view showing a state before the nip is released according to step S11, FIG. 5B is a schematic view showing a state in which the nip release operation is being executed, and FIG. 5C is a schematic view showing a state in which the dancer roller is operated. It is a schematic diagram which shows the state which is present. FIG. 7A is a schematic diagram showing a state before executing the process according to step S14, and FIG. 7B is a schematic diagram showing a state in which the process according to step S14 is being executed.

Step S1 (Start of printing process)
First, the operator operates the inkjet printing system 1 by operating an input unit (not shown) or the like. By this operation, the nip of the continuous paper WP by the nip rollers 25a to 25c is turned on and the drive rollers M1 to M4 rotate, so that the continuous paper WP is moved from the paper feed unit 5 to the paper discharge unit 7 along the transport direction J1. Will be transported to. Then, in the print area PA, the printing unit 19 prints on the continuous paper WP.

Step S2 (Stop printing process)
When it becomes necessary to temporarily stop the transportation of the continuous paper WP due to the discovery of an abnormality or the like, the operator stops the operation of the inkjet printing system 1 by operating an input unit (not shown) or the like. By the stop operation, the control unit 51 stops the operation of the drive mechanism (for example, the motor) that rotates each of the drive rollers M1 to M4. As a result, the transport and printing of the continuous paper WP are stopped.

Step S3 (Tension detection)
The difference in inertial force between the drive roller M3 and the drive roller M4 differs depending on the operation pattern of the stop process in step S2. The degree of slack generated in the continuous paper WP in the downstream region Wb of the drive roller M3 also differs depending on the difference in inertial force. Therefore, the tension sensor TP3 detects the tension of the continuous paper WP in the downstream region Wb, and the subsequent processing is branched according to the output of the tension sensor TP3 (step T1).

In this embodiment, the content of the tension adjustment process is configured to be different with the reference value Bo as the threshold value. As an example, the reference value Bo is predetermined as a value of tension low enough to cause buckling in the continuous paper WP, and is stored in advance in the storage unit 57. The reference value Bo can be appropriately changed according to various conditions such as the thickness of the continuous paper WP and the constituent materials.

Step S4 (Activate the drive roller)
When the output of the tension sensor TP3 is equal to or higher than the reference value Bo, as shown in FIG. 2C or FIG. 4A, the slack generated in the continuous paper WP in the downstream region Wb is relatively small. Therefore, when the tension of the downstream region Wb is equal to or higher than the reference value Bo, the process proceeds to step S4 to start the tension adjustment process.

In the tension adjustment process according to step S4, as shown in FIG. 4B, the nip rollers 25a to 25c are arranged downstream of the downstream region Wb while maintaining the state (nip state) of sandwiching the continuous paper WP. The drive roller M4 is rotated in the forward direction. Since the continuous paper WP is pulled to the downstream side by the rotation, the tension of the continuous paper WP that has been lowered increases.

When the slack generated in the continuous paper WP in the downstream region Wb is relatively small, there is a great risk that the continuous paper WP in the loosened state will be damaged when it passes through the nip roller 25c due to the rotation of the drive roller M4. Is small. Further, when the continuous paper WP is transported in the transport direction J1, there is no limit to the transportable distance of the continuous paper WP. Therefore, by rotating the drive roller M4 in the forward direction, the tension of the continuous paper WP can be reliably restored to the target value Ln while avoiding the situation where the continuous paper WP is damaged (FIG. 4 (b), FIG. (Figure below). The step according to step S4 corresponds to the first recovery step in the present invention.

Step S5 (Resume printing process)
After the output of the tension sensor TP3 recovers from F1 to the target value Ln, the printing process is restarted. That is, the control unit 51 rotates the drive rollers M1 to M4 in the forward direction in the same manner as in step S1 by using the output of the tension sensor TP3 or the like recovered to the target value Ln as a trigger (FIG. 4 (c)). By the rotation control, the continuous paper WP is conveyed again in the conveying direction J1 and printing is performed by the printing unit 19.

As described above, when the output value of the tension sensor TP3 detected in step S3 is equal to or higher than the reference value Bo, the process proceeds from step S3 to step S4, and the tension is adjusted by the process related to step S4. On the other hand, when the output value of the tension sensor TP3 is smaller than the reference value Bo, the process proceeds from step S3 to step S11.

Step S11 (Release of nip)
When the output of the tension sensor TP3 is smaller than the reference value Bo, as shown in FIG. 2D or FIG. 5A, the slack generated in the continuous paper WP in the downstream region Wb is large, and the continuous paper WP in the relevant portion has a large amount of slack. Buckling may occur. Further, when the stop processing according to step S2 is performed, a part of the continuous paper WP that is largely loosened becomes the nip roller 25c arranged on the downstream side of the downstream region Wb due to the rotation of the drive roller M3 due to inertia. You may get caught. If the continuous paper WP is conveyed while the loose continuous paper WP is caught in the nip roller 25c, there is a concern that the continuous paper WP may break.

Therefore, when the tension of the downstream region Wb is equal to or higher than the reference value Bo, the process proceeds to step S11 and the tension adjustment process is started. First, the driven roller moving unit 53 moves the driven roller N3 provided on the nip roller 25c under the control of the control unit 51. By the movement control, the driven roller N3 moves away from the driving roller M4 as shown in FIG. 5 (b). As a result, the nip state of the continuous paper WP by the nip roller 25c is released.

When the nip by the nip roller 25c is released, the slack of the continuous paper WP accumulated in the downstream region Wb is transmitted to the downstream side beyond the portion sandwiched by the nip roller 25c. As a result, as shown in FIG. 5B, the slack of the continuous paper WP in the downstream region Wb becomes relatively small, so that the tension of the continuous paper WP in the downstream region Wb increases to some extent.

In this embodiment, after releasing the nip state by the nip roller 25c, the dancer roller 71 provided in the buffer mechanism 7b of the paper ejection unit 7 is operated as shown in FIG. 5 (c). That is, as the dancer roller 71 rises from the initial position indicated by the dotted line to the position indicated by the solid line, the continuous paper WP is pulled to the downstream side. Therefore, by operating the dancer roller 71, at least a part of the slack generated in the continuous paper WP on the downstream side of the drive roller M3 is eliminated, and the tension of the continuous paper WP in the downstream region Wb is further increased.

Step S12 (re-execution of nip)
A predetermined time has passed since the nip by the nip roller 25c was released, and after the slack of the continuous paper WP in the downstream region Wb became small, the nip of the continuous paper WP by the nip roller 25c was again controlled by controlling the driven roller moving portion 53. Turn it on. That is, as shown in FIG. 6, the driven roller moving unit 53 moves the driven roller N3 so as to approach the driving roller M4 under the control of the control unit 51. By the drive control, the nip roller 25c again sandwiches the continuous paper WP. That is, the nip by the nip roller 25c is turned on again, and the continuous paper WP can be conveyed by the drive roller M4.

Step S13 (Tension detection)
By the process according to steps S11 to S12, the tension of the continuous paper WP in the downstream region Wb is increased. Therefore, the tension of the continuous paper WP in the downstream region Wb is detected by measuring the output value of the tension sensor TP3 again. Then, the subsequent processing is branched according to the output of the tension sensor TP3 (step T2).

When the output of the tension sensor TP3 detected in step S13 is equal to or higher than the reference value Bo, as shown in FIG. 4A, the slack generated in the continuous paper WP in the downstream region Wb is relatively small. That is, even if the continuous paper WP passes through the nip roller 25c, the risk of buckling or the like or breakage of the continuous paper WP is very small.

Therefore, when the tension of the downstream region Wb is equal to or higher than the reference value Bo, the process proceeds to step S4 and the tension adjustment process is started. That is, as shown in FIG. 4B, the drive rollers M4 arranged downstream of the downstream region Wb are rotated in the forward direction while maintaining the state in which the nip rollers 25a to 25c sandwich the continuous paper WP. .. The rotation pulls the continuous paper WP downstream, and the tension of the continuous paper WP recovers to the target value Ln. After that, the process proceeds to step S5, and the printing process is restarted.

Step S14 (Rewinding continuous paper)
On the other hand, if the output of the tension sensor TP3 detected in step S13 is smaller than the reference value Bo, the process proceeds to step S14. In this case, as shown in FIG. 7A, even if the nip state is released in step S11, the continuous paper WP in the downstream region Wb is still in a state of being greatly loosened.

In step S14, as shown in FIG. 7B, the continuous paper WP is conveyed in the direction opposite to the conveying direction J1 by rotating the drive motor M2 in the opposite direction (see reference numeral J2). At this time, the distance at which the continuous paper WP is conveyed in the reverse direction J2 is measured using a rotary encoder 13 or the like. The measured distance is stored in the storage unit 57 as the transport distance V1.

By transporting the continuous paper WP in the reverse direction J2 with the nip by the nip roller 25c turned on, the continuous paper WP is pulled in the reverse direction J2. Further, a part of the slack of the continuous paper WP in the downstream region Wb is dispersed in the continuous paper WP in the upstream region. Therefore, the slack of the continuous paper WP generated in the downstream region Wb is further eliminated, and the tension of the continuous paper WP increases. Further, since the continuous paper WP is conveyed in the reverse direction J2, it is possible to prevent a situation in which the continuous paper WP in a loosened state is caught in the nip roller 25c or the like and damaged in the downstream region Wb.

In this embodiment, after the continuous paper WP is conveyed in the reverse direction J2, the dancer roller 61 provided in the buffer mechanism 5b of the paper feed unit 5 is operated as shown in FIG. That is, as the dancer roller 61 rises from the initial position indicated by the dotted line to the position indicated by the solid line, the continuous paper WP is drawn to the upstream side. Therefore, the tension of the continuous paper WP is further increased by the operation of the dancer roller 61.

In this embodiment, after the drive roller M2 is rotated in the reverse direction to convey the continuous paper WP in the reverse direction J2, the dancer roller 61 is operated with the rotation of the drive roller M2 stopped, but the drive roller M2 is reversed. The dancer roller 61 may be operated while rotating. After operating the dancer roller 61 to further recover the tension, the process proceeds to step S15.

Step S15 (Tension detection)
By the process according to step S14, the tension of the continuous paper WP in the downstream region Wb increases. Therefore, the tension of the continuous paper WP in the downstream region Wb is detected by measuring the output value of the tension sensor TP3 again. Then, the subsequent processing is branched according to the output of the tension sensor TP3 (step T3).

Step S16 (Feeding out continuous paper)
When the output of the tension sensor TP3 detected in step S15 is equal to or higher than the reference value Bo, it is determined that the tension of the continuous paper WP has been improved, and the process proceeds from step S15 to step S16. When the process proceeds to step S16, the control unit 51 controls each of the drive rollers M1 to M4 to rotate in the forward direction. By this control, as shown in FIG. 9, the continuous paper WP is conveyed in the conveying direction J1.

In this embodiment, the rotation of the drive rollers M1 to M4 is controlled so that the distance at which the continuous paper WP is conveyed in the transfer direction J1 in step S16 is the transfer distance V1 stored in step S14. By equalizing the distance at which the continuous paper WP is conveyed in the reverse direction J2 in step S14 and the distance at which the continuous paper WP is conveyed in the transfer direction J1 in step S16, the position of the continuous paper WP is related to step S2. It will return to the position at the time when the print stop processing was executed. Therefore, when the printing process is restarted in step S5, it is possible to avoid a situation in which the information to be printed deviates from the originally planned location.

Further, in step S16, the rotation amount of the drive rollers M1 to M4 is controlled so that the rotation amount of the drive roller on the downstream side is larger than the rotation amount of the drive roller on the upstream side among the drive rollers M1 to M4. Is preferable. By controlling the amount of rotation of each of the drive rollers M1 to M4 in this way, a force for pulling the continuous paper WP downstream is applied when the continuous paper WP is sent out in the transport direction J1. Therefore, the tension of the continuous paper WP can be restored to the target value Ln while sending out the continuous paper WP.

After confirming that the tension of the continuous paper WP has recovered to the target value Ln by referring to the output value of the tension sensor TP2 or the tension sensor TP3, the process proceeds to step S5 to restart the printing process. That is, the control unit 51 rotates the drive rollers M1 to M4 in the forward direction in the same manner as in step S1. By the rotation control, the continuous paper WP is conveyed again in the conveying direction J1 and printing is performed by the printing unit 19.

Step S17 (Notification processing)
When the output of the tension sensor TP3 detected in step S15 is smaller than the reference value Bo, the tension of the continuous paper WP is not sufficiently recovered by the automatic tension adjustment process according to step S11 and thereafter. In such a case, as an example, it is considered that a situation has already occurred in which the continuous paper WP is broken in the lateral direction. Therefore, when the output of the tension sensor TP3 is smaller than the reference value Bo, the process proceeds from step S15 to step S17.

By shifting to step S17, the control unit 51 operates the notification unit 55. The notification unit 55 notifies the operator that the tension of the continuous paper WP has not been recovered by the automatic tension adjustment process by an alarm sound or lighting of a lamp. The operator manually adjusts the continuous paper WP by detecting the operation of the notification unit 55. As an example, after removing the broken continuous paper WP and winding a new continuous paper WP along the transport path, the printing process is restarted. The series of processes related to step S11 and subsequent steps performed when the output of the tension sensor TP3 detected in step S3 is smaller than the reference value Bo corresponds to the second recovery step in the present invention.

<Effect of the configuration of the example>
In the conventional printing apparatus, when the transfer and printing of the continuous paper WP are stopped, a transfer error frequently occurs due to a decrease in the tension of the continuous paper WP when the transfer and printing are restarted. When the tension of the reduced continuous paper WP is manually restored, the required time becomes longer and the burden on the operator increases.

In the present invention, the process of recovering the tension of the continuous paper WP to the target value Ln is changed according to the tension value of the continuous paper WP in the state where the transport of the continuous paper WP is stopped. That is, when the transport is stopped relatively gently, the amount of decrease in the tension of the continuous paper WP in the downstream region Wb of the drive roller M3 having a large inertia is relatively small, and the slack generated in the continuous paper WP is also relatively small. When the tension of the continuous paper WP is equal to or higher than the predetermined reference value Bo or more, the tension of the continuous paper WP is restored by driving the drive roller M4 or the like without operating the driven roller moving unit 53.

That is, since it is not necessary to switch the nip state of the continuous paper WP on and off by the nip roller 25c or the like, the process and time required for tension recovery can be shortened. Since the slack generated in the continuous paper WP is small, even if the continuous paper WP is conveyed while the nip by the nip roller 25c is kept on, the continuous paper WP may be caught in the nip roller 25c and broken. The risk of occurrence is also very small. Therefore, the tension recovery process can be completed more quickly and more reliably.

On the other hand, when the transfer is stopped relatively rapidly due to high urgency, the slack generated in the continuous paper WP in the downstream region Wb of the drive roller M3 having a large inertia is relatively large, and the amount of decrease in the tension of the continuous paper WP is compared. Large. When the continuous paper WP is conveyed by pulling it in the conveying direction J1 in such a state of large slack, there is a concern that the continuously slackened continuous paper WP is caught in the nip roller 25c, buckled, and broken.

Further, in a general printing apparatus, since the distance that the continuous paper WP can be conveyed in the reverse direction J2 is limited, the tension of the continuous paper WP is sufficiently recovered by conveying the continuous paper WP in the reverse direction J2. It is difficult to make it. That is, for the purpose of preventing the slack from being transmitted to a configuration in which a large amount of continuous paper WP is loaded, for example, the feeding mechanism 5a of the paper feed unit 5, the continuous paper WP is moved in the reverse direction J2. There is a limit to the distance that can be transported to. As an example, the upper limit of the distance that can be conveyed in the reverse direction J2 in a general printing apparatus is about 40 mm to 60 mm.

Therefore, when the tension of the continuous paper WP is lower than the reference value Bo, the driven roller moving unit 53 is operated to release the nip state of the continuous paper WP by the nip roller 25c. By temporarily releasing the nip state, the slack of the continuous paper WP accumulated in the downstream region Wb is dispersed from the downstream region Wb to a further downstream region. As a result, the tension in the downstream region Wb can be increased.

Then, after a predetermined time has elapsed after releasing the nip, the continuous paper WP is returned to the nip state and conveyed in the reverse direction J2. Since the continuous paper WP is transported so as to be pulled in the reverse direction J2 instead of the transport direction J1, it is possible to avoid a situation in which the continuous paper WP in the downstream region Wb where slack occurs is caught in the nip roller 25c and breaks. Further, by releasing the nip once, the tension of the continuous paper WP in the downstream region Wb has already been recovered to some extent. Therefore, even when the distance to be conveyed in the reverse direction J2 is limited to a short distance, it becomes easy to restore the tension of the continuous paper WP to the target value Ln by the transfer of the distance.

In this way, the tension of the continuous paper WP is recovered by changing the content of the process of automatically recovering the tension according to the tension value of the continuous paper WP in the state where the driving of the drive rollers M1 to M4 is stopped. The process of making it can be executed more appropriately. That is, when the drive rollers M1 to M4 are stopped gently and the degree of slack generated in the continuous paper WP is small, the tension adjusting step that can be completed in a short time, that is, the tension recovery process according to step S4 is executed. Therefore, it is possible to avoid a situation in which the operating efficiency of the printing apparatus is unnecessarily lowered as a result of performing the processing for a long processing time even though the slack generated in the continuous paper WP is small.

When the drive rollers M1 to M4 are suddenly stopped and the degree of slack generated in the continuous paper WP is large, the tension adjustment step in which the tension recovery efficiency is high even if the operating time is long, that is, the tension recovery process according to step S11 and subsequent steps. To execute. Therefore, as a result of performing a process in which the tension recovery efficiency is small even though the slack generated in the continuous paper WP is large, a situation in which the continuous paper WP is broken or a transport error in the continuous paper WP occurs after printing is restarted. It can be avoided.

It should be noted that the examples disclosed this time are examples in all respects and are not restrictive. The scope of the present invention includes the scope of claims and all modifications within the meaning and scope equivalent to the scope of claims. As an example, the present invention can be modified as follows.

(1) In the above-described embodiment, the step according to step S4 raises the tension of the continuous paper WP only by controlling the drive roller M4 located downstream from the downstream region Wb to be rotationally driven in the forward direction. The process according to the above is not limited to this. That is, as shown in FIG. 10, while the drive roller M4 arranged on the downstream side of the downstream area Wb is rotationally driven in the forward direction, the drive roller M2 arranged on the upstream side of the downstream area Wb is driven in the reverse direction. May be rotationally driven.

In this case, the continuous paper WP is not only pulled in the transport direction J1 but also in the reverse direction J2, so that the tension of the continuous paper WP can be increased more efficiently. The process according to step S4 may be executed only by controlling the drive roller M2 arranged on the upstream side of the downstream region Wb to be rotationally driven in the opposite direction.

(2) In the above-described embodiment, the dancer roller 71 is operated in step S11 to reduce the slack generated in the continuous paper WP on the downstream side of the drive roller M3, but the present invention is not limited to this. .. That is, in the inkjet printing system 1, it is not necessary to dispose the dancer roller 71. Similarly, in the inkjet printing system 1, it is not necessary to dispose the dancer roller 61.

(3) In the above-described embodiment, as the nip roller arranged on the upstream side of the drive roller M3, the nip roller 25b corresponds to the second nip roller according to the present invention, but the present invention is not limited to this. .. That is, instead of the nip roller 25b, the nip roller 25a may correspond to the second nip roller according to the present invention. In this case, the continuous paper WP may be rewound in the reverse direction J2 by rotationally driving the drive roller M1 in the reverse direction in step S14 or the like. Further, both the nip roller 25b and the nip roller 25a may correspond to the second nip roller according to the present invention. That is, in step S14 or the like, both the drive roller M1 and the drive roller M2 may be rotationally driven in the opposite directions.

(4) In the above-described embodiment, the output value of the tension sensor TP3 arranged on the downstream side of the drive roller M3 is detected, and the content of the tension adjustment process is different by comparing the output value with the reference value Bo. However, the configuration is not limited to this. That is, the output of the tension sensor TP2 arranged on the upstream side of the drive roller M3 may be measured. In this case, the tension sensor TP2 corresponds to the second tension sensor in the present invention.

In such a modification, as an example, in step S16, not only the tension of the continuous paper WP in the downstream region Wb is measured by detecting the output value of the tension sensor TP3, but also the output value of the tension sensor TP2 is detected. Also measures the tension of the continuous paper WP in the upstream region Wf. Then, the tension of the continuous paper WP is restored to the target value Ln in both the downstream region Wb and the upstream region Wf, so that the process proceeds to step S5.

When measuring the tension of the upstream region Wf with the tension sensor TP2, the tension is monitored over a wider range than when measuring the tension of only the downstream region Wb, so printing is performed with some slack remaining on the continuous paper WP. It is possible to more reliably avoid the occurrence of a situation such as restarting the process. The tension sensor TP1 may be used as the second tension sensor in the present invention instead of the tension sensor TP2.

(5) In the above-described embodiment, the configuration is not limited to the configuration in which the continuous paper WP is used as the print medium. Another example of the print medium is a long thin layer material such as a film.

(6) In the above-described embodiment, the inkjet printing system is exemplified as the printing apparatus according to the present invention, but the configuration according to the present invention can also be applied to a printing apparatus other than the inkjet type, for example, an offset printing press.

(7) In the above-described embodiment, the transport path of the continuous paper WP is not limited to the configuration shown in FIG. Further, the shapes, numbers, and arrangements of the drive rollers M1 to M4, the driven rollers N1 to N3, and the transport rollers 11 may be appropriately changed as long as the effects according to the present invention can be obtained.

1 ... Inkjet printing system 3 ... Inkjet printing device 5 ... Feeding unit 5a ... Feeding mechanism 7 ... Paper ejection unit 7a ... Winding mechanism 11 ... Conveying roller 13 ... Rotary encoder 19 ... Printing unit 19a-19d ... Inkjet head 23 ... Inspection Units 25a to 25c ... Nip roller TP1 to TP3 ... Tension sensor 51 ... Control unit 53 ... Driven roller moving unit 55 ... Notification unit 57 ... Storage unit M1 ... Drive roller M2 ... Drive roller M3 ... Drive roller (main roller)
M4 ... Drive roller N1 to N3 ... Driven roller

Claims

A delivery section that sends out long print media,
A winding unit that winds up the print medium and
A printing unit that prints on the print medium and
A main roller disposed between the feeding portion and the winding portion,
A first nip roller having a first drive roller and a first driven roller having a smaller inertia than the main roller and arranged between the take-up portion and the main roller, and a first nip roller.
A second nip roller having a second drive roller and a second driven roller and arranged between the delivery portion and the main roller,
In a printing apparatus including a first tension sensor that detects the tension of the printing medium between the main roller and the first nip roller.
The print medium is driven by driving each of the main roller, the first drive roller, and the second drive roller in the transport direction, which is the direction in which the print medium is conveyed when printing is performed by the printing unit. In the normal transport process of transporting the feed from the feed section to the take-up section,
A first tension detection step that detects the output of the first tension sensor when the normal transfer process is stopped, and a first tension detection step.
A tension recovery step of recovering the tension of the print medium to the tension value in the normal transfer step by performing different recovery processes according to the output value detected in the first tension detection step is provided.
The tension recovery step is
When the output detected in the first tension detection step is equal to or higher than a predetermined reference value, the first drive roller is driven in the transport direction while the print medium is nipped by the first nip roller. The first recovery step of executing at least one of the operation of driving and the operation of driving the second drive roller in the direction opposite to the transport direction.
When the output detected in the first tension detection step is smaller than the reference value, the nip release step of releasing the nip of the print medium by the first nip roller and the first release step after a predetermined time has elapsed from the nip release step. A second recovery step including a nip recovery step of niping the print medium by the nip roller of the above, and a drive step of driving the second drive roller in a direction opposite to the transport direction after the nip recovery step.
A tension adjustment method characterized by having.
In the tension adjusting method according to claim 1,
The second recovery step is
A second tension detection step for detecting the output of the first tension sensor is provided after the nip recovery step.
When the output detected in the second tension detection step is smaller than the reference value, the tension of the print medium is recovered by executing the drive step, and the output detected in the second tension detection step is the reference. A tension adjusting method for recovering the tension of the print medium by executing the first recovery step instead of the driving step when the value is equal to or higher than the value.
In the tension adjusting method according to claim 1 or 2.
In the driving step, a distance storage step is further performed in which the distance at which the print medium is conveyed in the opposite direction is stored as the reverse conveying distance by driving the second driving roller in the opposite direction.
A tension adjusting method characterized in that after the tension recovery step, the print medium is fed forward by the amount of the reverse transport distance, and then the normal transport process is restarted.
In the tension adjusting method according to any one of claims 1 to 3,
A tension adjusting method, characterized in that, in the driving step, the second driving roller is driven in the opposite direction and the first driving roller is driven in the forward direction.
In the tension adjusting method according to any one of claims 1 to 4,
The printing apparatus includes a second tension sensor that detects the tension of the printing medium between the main roller and the second nip roller.
The tension recovery step is
A tension adjusting method comprising a third tension detecting step of detecting an output of the second tension sensor after the driving step.
In the tension adjusting method according to any one of claims 1 to 5.
The printing apparatus includes a dancer roller disposed between the take-up portion and the first nip roller.
It is characterized by comprising a slack eliminating step in which at least a part of the slack of the printing medium between the winding portion and the main roller is eliminated by the dancer roller in a state where the nip is eliminated by the nip releasing step. Tension adjustment method.
A delivery section that sends out long print media,
A winding unit that winds up the print medium and
A printing unit that prints on the print medium and
A main roller disposed between the feeding portion and the winding portion,
A first nip roller having a first drive roller and a first driven roller having a smaller inertia than the main roller and arranged between the take-up portion and the main roller, and a first nip roller.
A second nip roller having a second drive roller and a second driven roller and arranged between the delivery portion and the main roller,
A first tension sensor that detects the tension of the print medium between the main roller and the first nip roller, and
The print medium is driven by driving each of the main roller, the first drive roller, and the second drive roller in the transport direction, which is the direction in which the print medium is conveyed when printing is performed by the printing unit. The output of the first tension sensor is detected when the normal transfer process is stopped, and different processes are performed according to the output value of the first tension sensor. A control unit that controls the transfer of the print medium so as to restore the tension of the print medium to the value of the tension in the normal transfer process is provided.
The control unit
When the output of the first tension sensor is equal to or higher than a predetermined reference value, the operation of driving the first drive roller in the transport direction while the print medium is nipped by the first nip roller. Control is performed to execute at least one of the operations of driving the second drive roller in the direction opposite to the transport direction.
When the output of the first tension sensor is smaller than the reference value, the nip of the print medium is released by the first nip roller, and the first nip roller releases the nip of the print medium after a predetermined time has elapsed from the release of the nip of the print medium. A printing apparatus characterized in that the print medium is nipped and the second drive roller is driven in a direction opposite to the transport direction while the print medium is niped.