Patent Publication Number: US-10308459-B2

Title: Medium wind-up apparatus

Description:
BACKGROUND 
     1. Technical Field 
     The present invention relates to a medium wind-up apparatus. 
     2. Related Art 
     A printer, which is an example of a medium wind-up apparatus, will be described. Among printers, apparatuses that are configured to rewind a medium by rotating a roll body in a direction that is opposite to that during reeling out using a roll motor in order to resolve sagging caused in the medium between the roll body and a transport driving roller, are known (refer to JP-A-2009-280398). 
     In a medium wind-up apparatus, in a case in which the roll load, that is, the load that is placed on a motor when a roll body is rotated, is increased in order to prevent a circumstance in which sagging occurs in the medium as a result of the rotation of the roll body being delayed, when the output torque of the motor is set to be high, the current that flows through the motor also increases. 
     SUMMARY 
     An advantage of some aspects of the invention is to provide a medium wind-up apparatus that can reduce the current that flows through a motor. 
     According to an aspect of the invention, there is provided a medium wind-up apparatus including a motor, which is a driving source that winds up a medium, a control portion that controls the motor on the basis of a torque limit value, which regulates an upper limit of an output torque of the motor, and a detection portion that detects a rotation speed of the motor, in which the control portion changes the torque limit value on the basis of the detected rotation speed. 
     According to this configuration, since the torque limit value is changed on the basis of the detected rotation speed, a circumstance in which the motor operates at an output torque that is unnecessarily high is suppressed. As a result of this, it is possible to reduce the current that flows through the motor. 
     In this case, it is preferable that the control portion decrease the torque limit value in a case in which the detected rotation speed exceeds a threshold value. 
     According to this configuration, the output torque is decreased after the detected rotation speed exceeds the threshold value. Therefore, in a case in which the motor is rotating at high speed, a circumstance in which the motor operates at an output torque that is unnecessarily high is suppressed. 
     In this case, it is preferable that the control portion increase the torque limit value in a case in which the detected rotation speed falls below a threshold value. 
     According to this configuration, it is possible to decrease the output torque until the detected rotation speed falls below the threshold value. Therefore, a circumstance in which the motor operates at an output torque that is unnecessarily high is suppressed. In addition, since the output torque is increased after the detected rotation speed falls below the threshold value, even in a case in which sagging occurs in the medium as a result of the rotation speed of the motor decreasing, it is possible to reduce the sagging of the medium. 
     In this case, it is preferable that the control portion increase the torque limit value in a case in which the detected rotation speed falls below a first threshold value, and that the control portion reduce the torque limit value in a case in which the detected rotation speed exceeds a second threshold value, which is larger than the first threshold value. 
     According to this configuration, after the detected rotation speed exceeds the second threshold value, the output torque is decreased until the detected rotation speed falls below the first threshold value. In addition, since the output torque is increased after the detected rotation speed falls below the first threshold value, even in a case in which sagging occurs in the medium as a result of the rotation speed of the motor decreasing, it is possible to reduce the sagging of the medium. Furthermore, the output torque is decreased again when the rotation speed of the motor is increased and the detected rotation speed exceeds the second threshold value as a result of the output torque increasing. Accordingly, it is possible to reduce sagging that occurs in the medium, and it is possible to suppress a circumstance in which the motor operates at an output torque that is unnecessarily high. 
     In this case, it is preferable that the medium wind-up apparatus further include a reel-out portion that includes the motor and in which a roll body, around which the medium is wound, is set, and a wind-up portion that winds up the medium that is reeled out from the roll body, and that the control portion change the torque limit value on the basis of the detected rotation speed when the medium wound up by the wind-up portion is rewound by the reel-out portion. 
     According to this configuration, it is possible to reduce the current that flows through the motor when the medium that is wound up by the wind-up portion is rewound by the reel-out portion. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The invention will be described with reference to the accompanying drawings, wherein like numbers reference like elements. 
         FIG. 1  is a view that shows a schematic configuration of a recording apparatus according to an embodiment of the invention. 
         FIG. 2  is a control block diagram relating to a medium feeding mechanism of the recording apparatus. 
         FIG. 3  is a view for describing changes in a roll load. 
         FIG. 4  is a view for describing a reference example of a control method of a reel-out motor. 
         FIG. 5  is a view for describing a control method of a reel-out motor of the present embodiment. 
     
    
    
     DESCRIPTION OF EXEMPLARY EMBODIMENTS 
     Hereinafter, a recording apparatus  1 , which is an embodiment of a medium wind-up apparatus of the invention, will be described with reference to the appended drawings. 
     A schematic configuration of the recording apparatus  1  will be described on the basis of  FIG. 1 . The recording apparatus  1  is a recording apparatus that prints images on a medium P using an ink jet method while feeding the medium P. The recording apparatus  1  is provided with a medium feeding mechanism  2 , a platen  3 , a suction fan  4 , a recording portion  5 , a drying portion  6 , and a support frame  7  that supports these components. 
     The medium feeding mechanism  2  feeds a long form medium P to a wind-up side roll body  103  from a reel-out side roll body  101  using a roll-to-roll method. The reel-out side roll body  101  is a roll body in which the medium P is wound around a reel-out side core  101   a  (for example, a paper tube). The wind-up side roll body  103  is a roll body in which the medium P, which is reeled out from the reel-out side roll body  101  and on which an image is printed by the recording portion  5 , is wound up onto a wind-up side core  103   a.  Additionally, for example, various materials, such as paper, film, or fabric, can be used as the medium P. For example, the maximum width, maximum diameter (diameter), and maximum weight of a reel-out side roll body  101  that can be set in the recording apparatus  1  are respectively 64 inches (approximately 1.6 m), 250 mm, and 80 kg. The medium feeding mechanism  2  is provided with a reel-out portion  11 , a feeding portion  12 , and a wind-up portion  13 . 
     The reel-out side roll body  101  is set in the reel-out portion  11 . The reel-out portion  11  is provided with a reel-out side support portion  14  and a reel-out motor  21  (refer to  FIG. 2 ). The reel-out side support portion  14  supports the reel-out side roll body  101  so as to be capable of rotating. The reel-out motor  21  is a driving source that rotates the reel-out side roll body  101 . For example, it is possible to use a DC (Direct Current) motor as the reel-out motor  21 . As a result of the reel-out motor  21  rotating one of normally or in reverse, the reel-out side roll body  101  is rotated in a reel-out direction D 1  so that the medium P is reeled out from the reel-out side roll body  101 . In addition, as a result of the reel-out motor  21  rotating in the other of normally and in reverse, the reel-out side roll body  101  rotates in a rewind direction D 2  so that the medium P is rewound onto the reel-out side roll body  101 . 
     The feeding portion  12  feeds the medium P reeled out from the reel-out side roll body  101  toward the wind-up portion  13 . The feeding portion  12  is provided with a feeding roller  16  and a feeding motor  22  (refer to  FIG. 2 ). The feeding roller  16  is provided with a driving roller  18  and a driven roller  19 . The driving roller  18  and the driven roller  19  feed the medium P in a manner in which the medium P is held therebetween. The feeding motor  22  is a driving source that rotates the driving roller  18 . For example, it is possible to use a DC motor as the feeding motor  22 . As a result of the feeding motor  22  rotating one of normally or in reverse, the medium P is fed in a feeding direction D 3 . In addition, as a result of the feeding motor  22  rotating in the other of normally and in reverse, the medium P is fed in a reverse feeding direction D 4 , which is a direction that is opposite to the feeding direction D 3 . 
     The wind-up portion  13  winds up the medium P fed thereto in roll form. The wind-up portion  13  is provided with a wind-up side support portion  15  and a wind-up motor  23  (refer to  FIG. 2 ). The wind-up side support portion  15  supports the wind-up side core  103   a  so as to be capable of rotating. The tip end portion of the medium P is attached to the wind-up side core  103   a.  The wind-up motor  23  is a driving source that rotates the wind-up side core  103   a.  For example, it is possible to use a DC motor as the wind-up motor  23 . When the wind-up motor  23  is rotated one of normally or in reverse, the wind-up side core  103   a  rotates in a wind-up direction D 5 , and the medium P is wound up onto the wind-up side core  103   a.  As a result of this, the wind-up side roll body  103  is formed. When the wind-up motor  23  is rotated the other of normally and in reverse, the wind-up side core  103   a  rotates in a carryback direction D 6  that is opposite to the wind-up direction, and the medium P wound up on the wind-up side core  103   a  is carried back. 
     The platen  3  is provided further on the downstream side of a feeding pathway Pa than the feeding roller  16 . A plurality of suction holes  26 , which pass through the top and bottom of the platen  3 , are formed in the platen  3 . The suction fan  4  is provided below the platen  3 . As a result of the suction fan  4  being operated, the insides of the suction holes  26  reach negative pressures, and the medium P on the platen  3  is suction held. Ink is discharged onto the medium P that is suction held on the platen  3  from a recording head  27 , which will be mentioned later. 
     The recording portion  5  records images on the medium P. The recording portion  5  is provided with the recording head  27 , a carriage  28 , and a carriage movement mechanism  29 . The recording head  27  discharges ink onto the medium P adsorbed onto the upper surface of the platen  3 . The recording head  27  is mounted in the carriage  28 . The carriage movement mechanism  29  causes the carriage  28  to reciprocate in a direction that intersects the feeding direction D 3  of the medium P. 
     The drying portion  6  is provided further on the downstream side than the recording portion  5  in the feeding pathway Pa of the medium P that reaches from the reel-out side roll body  101  to the wind-up side roll body  103 . The drying portion  6  is provided with an aluminum plate  31 , and a tube heater  32  that is provided on the rear surface of the aluminum plate  31 . As a result of the tube heater  32  generating heat, drying of the medium P is accelerated when the medium P, to which ink has been applied, passes over the upper surface of the aluminum plate  31 . 
     A tension bar  34  is provided on the support frame  7 . The tension bar  34  is supported by a bar support shaft  35  to be capable of swinging. The tension bar  34  applies tension to the medium P as a result of coming into contact with the medium P that passes through the drying portion  6 . As a result of this, the medium P is wound up by the wind-up portion  13  in a state in which an appropriate amount of tension is applied to the medium P. 
     A control configuration relating to the medium feeding mechanism  2  of the recording apparatus  1  will be described on the basis of  FIG. 2 . The recording apparatus  1  is provided with a control portion  10 , a reel-out driver  41 , a feeding driver  42 , a wind-up driver  43 , a reel-out side detection portion  51 , a feeding detection portion  52 , and a wind-up side detection portion  53 . 
     The control portion  10  performs integrated control of each portion of the recording apparatus  1 . Although illustration is omitted from the drawings, the control portion  10  is provided with a central processing unit (CPU), read only memory (ROM), random access memory (RAM), programmable ROM (PROM), an application specific integrated circuit (ASIC), and a bus. 
     In addition, a host device (for example, a personal computer), which is not illustrated in the drawings, is connected to the control portion  10  in a manner in which communication can be performed. When a recording job is received from the host device, the control portion  10  controls each portion of the recording apparatus  1  on the basis of the received recording job. As a result of this, the recording apparatus  1  performs alternate repetition of a dot formation operation and a feeding operation. In this instance, the dot formation operation is an operation that discharges an ink from the recording head  27  while moving the carriage  28  in a direction that intersects the feeding direction D 3 , and can also be referred to as a main scan. The feeding operation is an operation that feed the medium P in the feeding direction D 3 , and can also be referred to as a sub-scan. 
     The reel-out driver  41 , the feeding driver  42 , and the wind-up driver  43  respectively drive the reel-out motor  21 , the feeding motor  22 , and the wind-up motor  23  on the basis of a pulse width modulation (PWM) signal that is output from the control portion  10 . 
     The reel-out side detection portion  51 , the feeding detection portion  52 , and the wind-up side detection portion  53  respectively detect the rotation speed of the reel-out motor  21 , the rotation speed of the feeding motor  22 , and the rotation speed of the wind-up motor  23 . For example, it is possible to use a rotary encoder provided in the reel-out motor  21  as the reel-out side detection portion  51 . The rotational position of the reel-out motor  21  is expressed as a count value of an output pulse from the reel-out side detection portion  51 , and the amount of change in the rotational position of the reel-out motor  21  per unit time corresponds to the rotation speed of the reel-out motor  21 . The same applies to the feeding detection portion  52  and the wind-up side detection portion  53 . 
     The recording apparatus  1 , which is configuration in this manner, is capable of rewinding the medium P wound up by the wind-up portion  13  to the reel-out portion  11  on the basis of an instruction, or the like, received by an operation panel, which is not illustrated in the drawings. At this time, the control portion  10  respectively controls the wind-up motor  23 , the feeding motor  22 , and the reel-out motor  21  so that the medium P is fed in the reverse feeding direction D 4  by the feeding roller  16  as a result of the wind-up side roll body  103  rotating in the carryback direction D 6 , and so that the reel-out side roll body  101  rotates in the rewind direction D 2 . Additionally, at this time, the control portion  10  performs PID control of the feeding motor  22  on the basis of a speed table that changes the speed in the order of acceleration, constant speed, and deceleration. 
     When the medium P wound up by the wind-up portion  13  is rewound by the reel-out portion  11 , the control portion  10  controls the reel-out motor  21  on the basis of a torque limit value so that the rotation of the reel-out side roll body  101  is not delayed with respect to feeding speed of the medium P by the feeding roller  16 , or so that the reel-out side roll body  101  does not pull the medium P too much, or the like. 
     The torque limit value is a value that regulates the upper limit of the output torque of the reel-out motor  21 . That is, for example, the control portion  10  compares a control value obtained by performing PID control based on the deviation between a target speed and a current speed of the reel-out motor  21  with the torque limit value. In a case in which the control value does not exceed the torque limit value, the control portion  10  outputs a duty value of the PWM signal based on the control value to the reel-out driver  41 . On the other hand, in a case in which the control value exceeds the torque limit value, the control portion  10  outputs a duty value of the PWM signal based on the torque limit value to the reel-out driver  41 . As a result of this, the upper limit of the output torque of the reel-out motor  21  is restricted to a value based on the torque limit value. 
     Incidentally, as shown in  FIG. 3 , the roll load, that is, the load (torque) that is applied to the reel-out motor  21  when the reel-out side roll body  101  is rotated, fluctuates in conjunction with the rotational period length of the reel-out side roll body  101  as a result of the influence of decentering of the reel-out side roll body  101 . Therefore, when the torque limit value is set to a value that corresponds to an average value of the fluctuating roll load, the output torque of the reel-out motor  21  falls below the roll load at a timing at which the roll load increases. In this case, the rotation of the reel-out side roll body  101  is delayed, and sagging occurs in the medium P between the reel-out side roll body  101  and the feeding roller  16 . 
     Therefore, in a control method of the reel-out motor  21 , which is a reference example of the invention, the torque limit value is set to a value (a first limit value L 1 ) that is higher than a value that corresponds to the maximum value of the fluctuating roll load. 
     The reference example of the control method of the reel-out motor  21  will be described specifically with reference to  FIG. 4 . In the example shown in  FIG. 4 , even at a timing at which the roll load increases, the output torque of the reel-out motor  21  based on the first limit value L 1  exceeds the roll load. Therefore, the medium P is retained in a state of being pulled taut between the reel-out side roll body  101  and the feeding roller  16 , and the reel-out motor  21  operates following the speed of the feeding motor  22 . In this manner, the medium P is stably rewound as a result of the control portion  10  controlling the reel-out motor  21  on the basis of the torque limit value, which is set to the first limit value L 1 . 
     Additionally, the roll load fluctuates depending on the rotation speed of the reel-out side roll body  101  and the radius of the reel-out side roll body  101 , but in order to simplify the description, in the examples shown in  FIGS. 4 and 5 , which will be mentioned later, the influence of such fluctuation will be treated as insignificant. In addition, in the examples shown in  FIGS. 4 and 5 , which will be mentioned later, the reel-out motor  21  outputs torque based on the torque limit value. That is, the control portion  10  outputs a duty value of the PWM signal based on the torque limit value rather than the control value to the reel-out driver  41 . 
     Incidentally, when the medium P is reeled out from the reel-out side roll body  101 , the reel-out motor  21  outputs torque that is lower than the roll load so that a predetermined amount of tension is applied to the medium P between the reel-out side roll body  101  and the feeding roller  16 . In contrast to this, when the medium P is rewound to the reel-out side roll body  101 , the reel-out motor  21  outputs torque that is higher than the roll load in the above-mentioned manner. Therefore, when the medium P is rewound, the reel-out motor  21  outputs higher torque than a case in which the medium is reeled out. Further, since a current that is proportionate to the output torque flows through the reel-out motor  21 , when the medium P is rewound, the current that flows through the reel-out motor  21  is greater than a case in which the medium is reeled out. 
     Additionally, in the above-mentioned reference example, since the control portion  10  sets the torque limit value to the same value (the first limit value L 1 ) in a case in which the roll load is small and in a case in which the roll load is large, the reel-out motor  21  outputs torque that is unnecessarily high in a case in which the roll load is small. Therefore, the current that flows through the reel-out motor  21  rises further. 
     As a result of this, particularly in a case in which the medium P is rewound for a long period of time, the amount of heat generation of the reel-out motor  21  exceeds a heat generation restriction amount, and it becomes necessary to take time in order to cool the reel-out motor  21 . Additionally, examples of cases in which the medium P is rewound over a long period of time include a case in which the medium P of a whole roll body is continuously rewound to the reel-out portion  11  from the wind-up portion  13  in order for a user to check the printing quality after printing of a whole reel-out side roll body  101  is performed. 
     In such an instance, in the present embodiment, the control portion  10  reduces the current that flows through the motor by altering the torque limit value in accordance with the rotation speed of the reel-out motor  21 , which is detected by the reel-out side detection portion  51 . That is, in a case in which the rotation speed of the reel-out motor  21  falls below a first threshold value Va, the control portion  10  sets the torque limit value to the first limit value L 1 . In addition, in a case in which the rotation speed of the reel-out motor  21  exceeds a second threshold value Vb, which is greater than the first threshold value Va, the control portion  10  sets the torque limit value to a second limit value L 2 , which is smaller than the first limit value L 1 . In other words, the control portion  10  makes the torque limit value high in a case in which a wind-up delay of the medium P occurs, but makes the torque limit value low in a case in which a wind-up delay of the medium P by the reel-out side roll body  101  does not occur. 
     For example, the control portion  10  sets a value obtained by adding the torque calculated from a set value of the tension applied to the medium P between the reel-out side roll body  101  and the feeding roller  16 , and the torque calculated from a measured value of the roll load. In this case, the control portion  10  alters the torque limit value by altering the set value of tension in accordance with the detected rotation speed of the reel-out motor  21 . 
     The control portion  10  performs such alteration control of the torque limit value during constant speed control of the feeding motor  22 . In a similar manner to that of the reference example, during acceleration control and deceleration control of the feeding motor  22 , the control portion  10  sets the torque limit value to the first limit value L 1  regardless of the detected rotation speed of the reel-out motor  21 . 
     A control method of the reel-out motor  21  of the present embodiment will be described specifically with reference to  FIG. 5 . In the example shown in  FIG. 5 , the rotation speed of the reel-out motor  21  exceeds the second threshold value Vb at a timing at which the feeding motor  22  switches to the constant speed control, that is, at a timing at which the alteration control of the torque limit value is initiated. Therefore, the control portion  10  alters the torque limit value from the first limit value L 1  to the second limit value L 2 . As a result of this, the output torque of the reel-out motor  21  is low, but at this point in time, since the output torque is higher than the roll load, the rotation speed of the reel-out motor  21  does not decrease. 
     A timing t 1  of  FIG. 5  shows a timing at which the rotation speed turns into an increase after the rotation speed of the reel-out motor  21  decreases temporarily in order for the roll load to temporarily increase and exceed the output torque. As a result of the rotation speed of the reel-out motor  21  temporarily decreasing, sagging occurs in the medium P between the reel-out side roll body  101  and the feeding roller  16 , but thereafter, since the rotation speed of the reel-out motor  21  increases in accordance with a decrease in the roll load, the sagging of the medium P is resolved. After the sagging of the medium P is resolved, the medium P attains a pulled taut state, and the rotation speed of the reel-out motor  21  stabilizes. In this manner, in a case in which a state in which the roll load increases is temporary, the control portion  10  controls the reel-out motor  21  with the torque limit value still set as the second limit value L 2 . 
     The timing t 2  and the timing t 4  of  FIG. 5  show timings at which the rotation speed of the reel-out motor  21  continuously decreases and falls below the first threshold value Va in order for the roll load to increase and exceed the output torque. At these times, the control portion  10  alters the torque limit value from the second limit value L 2  to the first limit value L 1 . As a result of this, the output torque becomes higher than the roll load, and the rotation speed of the reel-out motor  21  continuously decreases in a temporary manner due to inertia, but thereafter, the rotation speed of the reel-out motor  21  increases. 
     The timing t 3  and the timing t 5  of  FIG. 5  show timings at which the rotation speed of the reel-out motor  21 , which was increased, exceeds the second threshold value Vb after the torque limit value is altered from the second limit value L 2  to the first limit value L 1 . At these times, the control portion  10  alters the torque limit value from the first limit value L 1  to the second limit value L 2 . As a result of this, the output torque becomes lower than the roll load, and the rotation speed of the reel-out motor  21  continuously increases in a temporary manner due to inertia, but thereafter, the rotation speed of the reel-out motor  21  decreases. 
     In this manner, in a case in which a state in which the roll is increased continues to a certain extent, the control portion  10  controls the reel-out motor  21  while repeatedly switches between the first limit value L 1  and the second limit value L 2 . 
     In the above-mentioned manner, the recording apparatus  1  of the present embodiment is provided with the reel-out motor  21 , the control portion  10 , and the reel-out side detection portion  51 . The reel-out motor  21  is a driving source that winds up the medium P. The control portion  10  controls the reel-out motor  21  on the basis of the torque limit value, which regulates the upper limit of the output torque of the reel-out motor  21 . The reel-out side detection portion  51  detects the rotation speed of the reel-out motor  21 . Further, the control portion  10  alters the torque limit value on the basis of the detected rotation speed of the reel-out motor  21 . 
     According to this configuration, since the torque limit value is altered on the basis of the detected rotation speed of the reel-out motor  21 , a circumstance in which the reel-out motor  21  operates at an output torque that is unnecessarily high, is suppressed. As a result of this, it is possible to reduce the current that flows through the reel-out motor  21 . Accordingly, it is possible to reduce the amount of heat generation of the reel-out motor  21 , and in particular, it is possible to reduce a circumstance in which the amount of heat generation of the reel-out motor  21  exceeds a heat generation restriction amount in a case in which the medium P is rewound over a long period of time. 
     In addition, in the recording apparatus  1  of the present embodiment, the control portion  10  decreases the torque limit value in a case in which the detected rotation speed of the reel-out motor  21  exceeds the second threshold value Vb. 
     According to this configuration, the output torque is decreased after the detected rotation speed of the reel-out motor  21  exceeds the second threshold value Vb. Therefore, in a case in which the reel-out motor  21  is rotating at high speed, a circumstance in which the reel-out motor  21  operates at an output torque that is unnecessarily high is suppressed. 
     In addition, in the recording apparatus  1  of the present embodiment, the control portion  10  increases the torque limit value in a case in which the detected rotation speed of the reel-out motor  21  falls below the first threshold value Va. 
     According to this configuration, the output torque is decreased until the detected rotation speed of the reel-out motor  21  falls below the first threshold value Va. Therefore, a circumstance in which the reel-out motor  21  operates at an output torque that is unnecessarily high is suppressed. In addition, since the output torque is increased after the detected rotation speed of the reel-out motor  21  falls below the first threshold value Va, even in a case in which sagging occurs in the medium P as a result of the rotation speed of the reel-out motor  21  decreasing, it is possible to reduce the sagging of the medium P. 
     In addition, in the recording apparatus  1  of the present embodiment, the control portion  10  increases the torque limit value in a case in which the detected rotation speed of the reel-out motor  21  falls below the first threshold value Va. In addition, the control portion  10  decreases the torque limit value in a case in which the detected rotation speed of the reel-out motor  21  exceeds the second threshold value Vb, which is larger than the first threshold value Va. 
     According to this configuration, after the detected rotation speed of the reel-out motor  21  exceeds the second threshold value Vb, the output torque is decreased until the detected rotation speed falls below the first threshold value Va. In addition, since the output torque is increased after the detected rotation speed of the reel-out motor  21  falls below the first threshold value Va, even in a case in which sagging occurs in the medium P as a result of the rotation speed of the reel-out motor  21  decreasing, it is possible to reduce the sagging of the medium P. Furthermore, the output torque is decreased again when the rotation speed of the reel-out motor  21  is increased and the detected rotation speed of the reel-out motor  21  exceeds the second threshold value Vb as a result of the output torque increasing. Accordingly, it is possible to reduce sagging that occurs is the medium P, and it is possible to suppress a circumstance in which the reel-out motor  21  operates at an output torque that is unnecessarily high. 
     In addition, the recording apparatus  1  of the present embodiment is provided with the reel-out portion  11  and the wind-up portion  13 . The reel-out portion  11  includes the reel-out motor  21 , and the reel-out side roll body  101 , around which the medium P is wound, is set therein. The wind-up portion  13  winds up the medium P reeled out from the reel-out side roll body  101 . Further, the control portion  10  alters the torque limit value on the basis of the detected rotation speed of the reel-out motor  21  when the medium P wound up by the wind-up portion  13  is rewound by the reel-out portion  11 . 
     According to this configuration, it is possible to reduce the current that flows through the reel-out motor  21  when the medium P wound up by the wind-up portion  13  is rewound by the reel-out portion  11 . 
     Additionally, the reel-out motor  21  is an example of a “motor”. The reel-out side detection portion  51  is an example of a “detection portion”. The first threshold value Va and the second threshold value Vb are examples of “threshold values”. The reel-out side roll body  101  is an example of a “roll body”. 
     The invention is not limited to the above-mentioned embodiment, and naturally, can adopt various configurations within a range in which that does not depart from the aim thereof. For example, the invention can be altered to have a format such as that below. 
     The control portion  10  is not limited to this configuration that alters the torque limit value between the first limit value L 1  and the second limit value L 2  in accordance with the detected rotation speed of the reel-out motor  21 , and may alter the torque limit value between three or more values. In addition, the control portion  10  may acquire a relationship equation of the torque limit value and the rotation speed of the reel-out motor  21  in advance, and alter the torque limit value by setting a value, which is obtained by substituting the detected rotation speed of the reel-out motor  21  into the relationship equation, as the torque limit value. 
     The control portion  10  may perform the alteration control of the torque limit value during acceleration control and deceleration control of the feeding motor  22  in addition to just during constant speed control of the feeding motor  22 . 
     In addition to a case in which the medium P is wound up by the reel-out motor  21 , the invention can also be applied to a case in which the medium P is wound up by the wind-up motor  23 . That is, the control portion  10  may alter the torque limit value of the wind-up motor  23  on the basis of the rotation speed of the wind-up motor  23  that is detected by the wind-up side detection portion  53 . 
     Application examples of the medium wind-up apparatus of the invention are not limited to an ink jet method recording apparatus, and for example, may also be a dot impact method recording apparatus, or an electrophotographic method recording apparatus. Furthermore, the invention is not limited to recording apparatuses and for example, the medium wind-up apparatus of the invention may also be applied to a drying device that carries out a drying treatment on a medium while feeding the medium or a surface treatment device that carries out a surface treatment on a medium while feeding the medium. In addition, the invention is not limited to a device that carries out such a process on a medium, and may also be applied to a device the merely winds up a medium. 
     This application claims priority under 35 U.S.C. § 119 to Japanese Patent Application No. 2016-059683, filed Mar. 24, 2016. The entire disclosure of Japanese Patent Application No. 2016-059683 is hereby incorporated herein by reference.