Patent Publication Number: US-10315445-B2

Title: Printing apparatus and sheet winding method

Description:
BACKGROUND OF THE INVENTION 
     Field of the Invention 
     The present invention relates to a printing apparatus having a sheet winding function of winding a sheet print medium (hereinafter also referred to simply as a sheet) in the form of a roll sheet. 
     Description of the Related Art 
     Conventionally, there is known a printing apparatus that can wind up a printed sheet into the form of a roll sheet while continuing a printing operation. Japanese Patent Laid-Open No. 2013-116561 discloses a printing apparatus having a plurality of roll sheet holding units, each of which can be used for both supplying a sheet to a printing unit and winding a sheet from the printing unit. 
     SUMMARY OF THE INVENTION 
     With the configuration of Japanese Patent Laid-Open No. 2013-116561, however, in the case of using the holding unit for winding, fixing a leading end of a sheet to a roll member for sheet winding requires a user to hold a sheet by hand to apply a tension to the sheet. This may place a burden on the user. Furthermore, at the conclusion of winding up the sheet, the user may also need to hold a rear (i.e., trailing) end of the sheet by hand to avoid loosening of the winding. 
     The present invention has been made to solve the above problems, and an object of the present invention is to provide a printing apparatus having a sheet winding function in which a burden on a user during sheet winding is reduced, and a sheet winding method. 
     A printing apparatus of the present invention for solving the above problems includes a mount unit configured to mount a roll sheet obtained by winding a continuous sheet into a roll shape; a driving unit configured to rotate the roll sheet mounted on the mount unit; a pressing member configured to press a surface of the roll sheet mounted on the mount unit; a printing unit configured to perform printing on the roll sheet supplied from the mount unit; and a control unit which controls the printing apparatus, wherein the control unit controls the pressing force of the pressing member such that, when the roll sheet is fed from the mount unit toward the printing unit, the pressing member presses a surface of the roll sheet at a first pressing force, and when printing is performed on a roll sheet by the printing unit, the pressing member employs a second pressing force that is smaller than the first pressing force to press a surface of the roll sheet. 
     According to the above configuration, in fixing the leading end of the sheet to the roll member for sheet winding, the pressing unit can apply a pressing force to the sheet, and can apply a tension to the sheet without involving the user&#39;s hand. In winding up the sheet to the trailing end, the pressing unit can apply a pressing force to the sheet, so as to avoid loosening of the winding. Accordingly, a printing apparatus having the sheet winding function is achieved in which a load on the user is reduced. 
     Further features of the present invention will become apparent from the following description of exemplary embodiments (with reference to the attached drawings). 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a view showing a configuration of a printing apparatus in a first usage form according to one embodiment; 
         FIGS. 2A to 2C  are views showing a movable configuration of a sheet discharge unit of the printing apparatus according to the embodiment; 
         FIGS. 3A and 3B  are views showing a spool member in the first usage form; 
         FIG. 3C  is a view showing the spool member and a mounting unit of the spool member in the first usage form; 
         FIGS. 4A and 4B  are views showing a sheet supply auxiliary mechanism/winding auxiliary mechanism; 
         FIG. 5  is a flow showing an operation sequence in sheet supply according to a first embodiment; 
         FIG. 6  is a flow showing an operation sequence in printing in the first usage form; 
         FIG. 7  is a flow showing an operation sequence in sheet winding-back; 
         FIG. 8  is a perspective view of the printing apparatus as viewed from a side of the sheet discharge unit; 
         FIG. 9  is a view showing a configuration of the printing apparatus in a second usage form; 
         FIGS. 10A and 10B  are views showing the spool member in the second usage form; 
         FIG. 11A  is a front view of the spool member in the first usage form; 
         FIG. 11B  is a front view of the spool member in the second usage form; 
         FIG. 12  is a view showing a configuration of the printing apparatus in the second usage form; 
         FIG. 13  is a flow showing an operation sequence in paper core attachment in the second usage form; 
         FIG. 14  is a flow showing an operation sequence in printing in the second usage form; 
         FIG. 15  is a flow showing an operation sequence in end processing in the second usage form; 
         FIG. 16  is a block diagram showing an example of a control system; 
         FIG. 17  is a flow showing an operation sequence in supplying in a first usage form according to a second embodiment; 
         FIG. 18  is a flow showing a winding-back operation sequence in the first usage form; 
         FIG. 19  is a flow showing an operation sequence in paper core attachment in a second usage form; 
         FIG. 20  is a flow showing an operation sequence in printing in the second usage form; 
         FIG. 21  is a flow showing an operation sequence in end processing in the second usage form; 
         FIG. 22  is a view showing a configuration of a printing apparatus in a second usage form according to a third embodiment; 
         FIG. 23  is a flow showing an operation sequence in printing in a second usage form according to a fourth embodiment; and 
         FIG. 24  is a flow showing an operation sequence while a drive motor is OFF in a second usage form according to a fifth embodiment. 
     
    
    
     DESCRIPTION OF THE EMBODIMENTS 
     The present invention can be applied to different types of image forming apparatuses, such as a printing apparatus, a copier, and a facsimile. By using an ink jet printing apparatus (hereinafter also referred to simply as a printing apparatus) as the image forming apparatus to which the present invention can be applied, embodiments of the present invention will be described with reference the attached drawings. 
     (Printing Apparatus) 
     A printing apparatus shown in  FIG. 1  has two conveying units  70  (upper and lower conveying units  70 ) arranged in a vertical direction, a sheet conveying unit  300 , a printing unit  400 , and a sheet discharge unit  500 . A sheet  1  is used as a print medium, and a long continuous sheet wound in a roll is attached to the conveying unit  70 . In the present specification, the continuous sheet wound in a roll will also be referred to as a roll sheet  1 . 
     The conveying unit  70  selectably has a function, as a supply unit, of drawing and supplying the sheet  1  from a roll portion of the attached roll sheet  1  and a function, as a winding unit, of winding up the sheet  1  printed in the printing unit  400  into a roll. 
     In the present specification, a usage form in a case where both of the upper and lower conveying units  70  are used as supply units is referred to as a “first usage form.” Meanwhile, a usage form in a case where one of the upper and lower conveying units  70  is used as a supply unit and the other is used as a winding unit is referred to as a “second usage form.” 
     (First Usage Form) 
     First, a description will be given of the usage form in a case where both of the upper and lower conveying units  70  are used as supply units (first usage form). 
     In  FIG. 1 , a spool member (roll member)  2  is inserted into a paper core of the roll sheet  1  and is axially supported by a holding unit of the conveying unit  70 . A rotational force is applied, by a roll drive motor (driving unit), to the spool member  2  which is axially supported by the holding unit of the conveying unit  70 , and this allows the spool member  2  to rotate in forward and backward directions. A plurality of auxiliary mechanisms  200  are provided in a sheet width direction, each having rollers  6  and  7  (rotators) arranged in a sheet supply direction. In a case where the conveying unit  70  is used as a supply unit, the auxiliary mechanism  200  serves as a sheet supply auxiliary mechanism. A conveying guide  8  guides both the front and back sides of the sheet  1  that has been supplied from the conveying unit  70  and leads the sheet  1  to the printing unit  400 . 
     A conveying roller  10  is rotatable in the forward and backward directions by a conveying roller drive motor. A conveying pinch roller  11  can be driven to rotate relative to the rotation of the conveying roller  10 . A conveying pinch roller separation motor (not shown) can switch the conveying pinch roller  11  between a separation state and a contact state relative to the conveying roller  10  and can change a nip pressure (pressing force) in the contact state. 
     Sheet leading end detection sensors  12  and  301  detect a leading end of the sheet  1  supplied from the conveying unit  70 . Detection of the leading end of the sheet  1  triggers rotation control of the above-mentioned roll drive motor, conveying roller drive motor, and conveying pinch roller separation motor or is used for detection of a paper jam. A platen  13  sucks and attaches the back side of the sheet  1  with a negative pressure generated by a suction fan  14  so that printing can be performed by a print head  15  with high precision. 
     The sheet discharge unit  500  cuts, by a cutter  16 , the sheet  1  when printing is finished, and stores the cut printed sheet  1  in a basket unit  62 . 
     A paper discharge guide  61  supports the back side of the printed sheet  1  and guides the printed sheet  1 . The paper discharge guide  61  is rotatable around a rotation center  61   a . In a case where the roll sheet  1  is attached to the upper conveying unit  70 , in  FIG. 1 , the paper discharge guide  61  is rotated in a clockwise rotation direction around the rotation center  61   a  from the state shown in  FIG. 1  to form a space at the front of the printing apparatus. The roll sheet  1  can be attached from that space. 
     A guide member  68  is a movable guide member which extends downward in a vertical direction from an end portion of the paper discharge guide  61  and is rotatably attached to the paper discharge guide  61  around an axis  68   a . It should be noted that in  FIG. 1 , the movable guide member  68  rotates in a counterclockwise direction around the axis  68   a  from the state shown in  FIG. 1  to be housed in the paper discharge guide  61 . The paper discharge guide  61  is provided with a position detection sensor  69  which detects that the movable guide member  68  is housed in the paper discharge guide  61 . 
     The basket unit  62  includes rods  63   a  to  63   d  as a structure body (frame) and a bag cloth  64  in which the discharged sheet  1  can be stored. The basket unit  62  is rotatable around a rotation center  65 . In a case where the roll sheet  1  is attached to the lower conveying unit  70 , in  FIG. 1 , the basket unit  62  is rotated in the counterclockwise rotation direction around the rotation center  65  from the state shown in  FIG. 1  to form a space at the front of the printing apparatus. The roll sheet  1  can be attached from that space. 
     A position detection sensor  67  of the basket unit  62  detects ON if the basket unit  62  is set as shown in  FIG. 1  and detects OFF if the basket unit  62  is rotated and is not in the state shown in  FIG. 1 , for example, when the basket unit  62  is in the states shown in  FIGS. 2B and 2C . 
     To an operation panel  20 , a user inputs the type of roll sheet  1  or the like. 
     (Configuration of Setting a Roll Sheet) 
     With reference to  FIGS. 3A to 3C , a description will be given of a configuration and a procedure of setting the roll sheet  1  on the printing apparatus.  FIG. 3A  is a front view of the spool member  2  in a disassembled state.  FIG. 3B  is a front view of the spool member  2  in an assembled state.  FIG. 3C  is a schematic cross-sectional view of an attachment unit for the roll sheet  1  in the side of the printing apparatus body. 
     In  FIG. 3A , the spool member  2  includes a spool shaft  21 , a friction member  22 , a reference spool flange  23 , a non-reference spool flange  24 , a spool gear  25 , and a supply flange attachment  26 . 
     The supply flange attachment  26  is removably attached to the reference spool flange  23  and the non-reference spool flange  24  by a hook having a spring property or the like. In the first usage form in which the conveying units  70  are kept being used as supply units, the supply flange attachment  26  does not need to be detached from the reference spool flange  23  and the non-reference spool flange  24 . The supply flange attachment  26 , the reference spool flange  23 , and the non-reference spool flange  24  may be integrally handled. As will be described later, it should be noted that in a case where the conveying unit  70  is used as a winding unit in the second usage form, the supply flange attachment  26  needs to be detached. 
     The non-reference spool flange  24  and the supply flange attachment  26  which are fitted to the spool shaft  21  are integrally detached, and the spool shaft  21  is inserted into the paper core of the roll sheet  1 . At this time, since there is a sufficient space between an inner diameter of the paper core of the roll sheet  1  and an outer diameter of the spool shaft  21 , a user can fit the roll sheet  1  to the spool shaft  21  by a small power. At the point when an end portion of the roll sheet  1  comes into contact with the supply flange attachment  26  in the side of the reference spool flange  23 , the friction member  22  provided on the inner side of the reference spool flange  23  in the usage position comes into contact with the inner surface of the paper core of the roll sheet  1 . 
     The non-reference spool flange  24  and the supply flange attachment  26  which have been detached are integrally engaged in the spool shaft  21 , and the friction member  22  provided on the inner side of the non-reference spool flange  24  in the usage position is brought into contact with the inner surface of the paper core of the roll sheet  1 . Accordingly, the paper core of the roll sheet  1  is locked and its movement relative to the spool member is prevented. The resulting state is shown in  FIG. 3B , and the spool member  2  to which the roll sheet  1  is mounted is set on the printing apparatus body. A reflection type sensor  28  is provided for the printing apparatus body, and determines whether the supply flange attachment  26  is in the attached state or not in the attached state. 
     In  FIG. 3C , a spool holder  31  is provided on each of the reference side and the non-reference side of the printing apparatus body and has a U-shaped cross-section. The spool member  2  may be fitted to or detached from a U-shaped opening of the spool holder  31 . A U-shaped bending portion has a diameter to mate with the spool shaft  21 . The spool gear  25  provided to rotate the spool member  2  is connected to a spool drive unit  30  on the side of the printing apparatus body to transmit the driving. The rotation operation of the spool member  2  allows a supply operation or a winding operation of the roll sheet  1 . The printing apparatus can detect the presence or absence of the spool member  2  by using a spool presence/absence detection sensor  32 . 
     (Auxiliary Mechanism) 
     With reference to the schematic views shown in  FIGS. 4A and 4B , a description will be given of a detailed configuration of an auxiliary mechanism  200  according to the present embodiment.  FIG. 4A  shows a cross section of the auxiliary mechanism  200  taken along the sheet supply direction of the printing apparatus.  FIG. 4B  shows a side of the auxiliary mechanism  200  as viewed from a downstream side of the sheet supply direction. 
     A rotation shaft  3  rotatably engages with the printing apparatus body and serves as a rotation shaft of the whole auxiliary mechanism  200 . The auxiliary mechanism  200  rotates around the rotation shaft  3 . The rotation shaft  3  rotatably engages with a portion  4   a  of an arm portion  4 , and both ends of the rotation shaft  3  are restricted in a thrust direction by a ring member (not shown). The arm portion  4  slidably engages with a shaft member  41  in a portion  4   b , and is positioned by urging a rotary cam  42  under the weight of the whole auxiliary mechanism  200 . The rotary cam  42  rotatably engages with a shaft member  43 , touches a surface of the arm portion  4 , and rotates by the driving from a driving mechanism (pressure drive motor), so as to change the position of the arm portion  4 . 
     A swinging member  5  rotatably engages with the shaft member  41  in an engaging unit  5   a , and both ends of the shaft member  41  are restricted in the thrust direction by a ring member (not shown). A driven rotation roller  6  and a sheet presser roller  7  are provided above the swinging member  5 . The rollers  6  and  7  are pressed against the roll sheet  1 . On the swinging member  5 , a roll outer diameter detection sensor  5   c  is arranged on a center portion between the driven rotation roller  6  and the sheet presser roller  7  to detect a distance from the roll sheet  1 . Each of the driven rotation roller  6  and the sheet presser roller  7  rotatably engages with a shaft member  47 , and both ends of the driven rotation roller  6  and the sheet presser roller  7  are restricted in the thrust direction by a ring member (not shown). 
     The shaft member  47  is fitted to an upper hole portion of the swinging member  5  and has a protrusion  47   a . A compression spring  46  is fitted to the protrusion  47   a  of the shaft member  47  and a protrusion  5   b  of the swinging member  5  and is restricted, and urges the shaft member  47  in an upper direction. The two rollers  6  and  7  are arranged to have an equal distance from the center position of the swinging member  5  and swing and rotate around the shaft member  41 , so that the pressing forces against the roll sheet  1  are uniform. Providing a plurality of rollers in an outer peripheral direction of the roll sheet  1  can effectively suppress expansion of the diameter of the roll portion of the roll sheet  1  and loosening of the winding. By rotating the roll sheet  1  via the spool member  2  in a state in which the rollers  6  and  7  are pressed against an outer peripheral surface of the roll sheet  1 , the sheet  1  is conveyed with a friction force of the roll sheet  1  itself. The auxiliary mechanism  200  pressurizes the sheet from a side below a horizontal surface which passes the center of the roll sheet  1 , that is, from a side below the roll sheet  1  in a vertical direction. 
     According to the above configuration of the auxiliary mechanism  200 , a warp of the roll sheet  1  having both ends supported by the spool member  2  is corrected, and conveyance precision that is higher than that in sheet supply can be obtained. 
     An operation area of the auxiliary mechanism  200  acting as a pressure mechanism with respect to the roll sheet  1  is below the roll sheet  1  in the vertical direction. Accordingly, it is possible to secure a space for setting a sheet when a heavy roll sheet is set, and the auxiliary mechanism  200  does not interfere with the setting operation. 
     Further, a conveying path of the sheet conveying unit  300  has a U-turn shape which starts from the lower side, whereas the conveying unit  70  uses a system which pressurizes the roll sheet  1  from the lower side. This system allows the sheet  1  to be supplied in a manner following the curl of the roll sheet  1 . Therefore, it is possible to minimize a conveying resistance in supplying and prevent a sheet surface from being scratched. 
     (Sheet Discharge Unit) 
     With reference to the schematic cross-sectional views of the printing apparatus shown in  FIGS. 2A to 2C  and the perspective view of the printing apparatus shown in  FIG. 8 , a description will be given of a detailed configuration of the sheet discharge unit  500 . 
       FIGS. 2A and 8  show a state in which the basket unit  62  is set in an available state in the sheet discharge unit  500 .  FIG. 2B  shows a state in which the movable guide member  68  is housed in the paper discharge guide  61  and a basket portion of the basket unit  62  is closed.  FIG. 2C  shows a state in which the basket unit  62  is housed below the lower conveying unit  70 . 
     In the present example, the paper discharge guide  61  is a mold component which forms a guide across the entire area in the sheet width direction. The movable guide member  68  is formed by forming/bending wires, and has two positions: a position in which the movable guide member  68  hangs under its own weight in the vertical direction and a position in which the movable guide member  68  is housed in the paper discharge guide  61 . Further, the paper discharge guide  61  is provided with the position detection sensor  69  for detecting that the movable guide member  68  is housed. The position detection sensor  69  detects OFF if the movable guide member  68  hangs under its own weight as shown in  FIG. 2A  and detects ON if the movable guide member  68  is housed as shown in  FIGS. 2B and 2C . 
     The basket unit  62  includes the rods  63   a  to  63   d  as a structure body (frame) and the bag cloth  64  in which the discharged sheet is stored. 
     The thrust direction (axial direction) of the rods  63   a  and  63   b  is the same as the sheet width direction. Each end of the rod  63   a  is connected to one end of the two rods  63   c . Each end of the rod  63   b  is connected to one end of the two rods  63   d . The other end of the rod  63   d  is connected to the rod  63   c . The other end of the rod  63   c  is rotatably attached to the rotation center  65  provided for a stand, and the rod  63   c  can rotate to the position substantially horizontal as shown in  FIG. 2B . From this state, the rod  63   c  is further movable in the thrust direction and can be housed below the lower conveying unit  70  as shown in  FIG. 2C . 
     The position detection sensor  67  for detecting a state of the basket unit  62  detects ON if the basket unit  62  is set as shown in  FIG. 2A  and detects OFF if the basket unit  62  is not set as shown in  FIGS. 2B and 2C . 
     In the set state shown in  FIG. 2A , the bag cloth  64  includes a portion  64   a  on the front side of the printing apparatus, a portion  64   b  on the floor side, and a portion  64   c  on the side of the back of the sheet to be discharged. The discharged sheet is received mainly by the portions  64   a  and  64   b , so as to prevent the printed surface from touching the ground and being smudged. The portion  64   c  has a function of guiding the back of the sheet during printing or discharging, and continuously guides the sheet from the paper discharge guide  61  and the movable guide member  68  so as to prevent the discharged sheet from entering the conveying unit  70 . If the discharged sheet enters the conveying unit  70 , a jam (paper jam) may occur. Accordingly, in a case where the position detection sensor  67  for detecting the state of the basket unit  62  or the position detection sensor  69  for detecting the state of the movable guide member  68  detects OFF indicating that either the basket unit  62  or the movable guide member  68  is housed, a warning is given to the user by the operation panel  20 . It should be noted that this is the case of the first usage form in which the conveying units  70  are used as supply units and the sheet is discharged to the basket. The second usage form in which the conveying unit  70  is used as a winding unit will be described later. 
     (Control System) 
     With reference to  FIG. 16 , a description will be given of a control system according to the present embodiment.  FIG. 16  is a block diagram showing a configuration of the control system in the present embodiment. A CPU  201  controls the conveying units  70  and the printing unit  400  according to a control program stored in a ROM  204 . To the CPU  201 , application selection information indicating whether the conveying unit  70  is for a supply use or for a winding use is inputted from the operation panel  20  via an input interface  202 . The inputted application selection information is written to or read from a RAM  203 . 
     The CPU  201  receives detection results of the spool presence/absence detection sensor  32  and the sheet leading end detection sensors  12  and  301  and ON/OFF signals from the position detection sensors  67  and  69  of the basket unit  62  and the movable guide member  68 . Further, the CPU  201  receives a trigger signal or the like involving a user operation from the operation panel  20 . Based on the received detection results and signals, the CPU  201  executes processing in connection with operation sequences (described later) according to a predetermined control program stored in the ROM  204 . 
     More specifically, the CPU  201  sends a rotation control signal to a pressure drive motor  33  of the upper and lower conveying units  70  to drive the pressure drive motor  33 . The auxiliary mechanism  200  rotates according to the operation of the pressure drive motor  33 . The CPU  201  receives a signal from the roll outer diameter detection sensor  5   c  and controls driving and stopping of the pressure drive motor  33 . 
     The CPU  201  further sends a rotation control signal also to a roll drive motor  34  and a conveying roller drive motor  35  of the upper and lower conveying units  70 . In response to the operations of the roll drive motor  34  and the conveying roller drive motor  35 , the CPU  201  receives signals from driving amount detection encoders  36  and  37  of the motors, and performs rotation control of the motors  34  and  35 . It should be noted that in the control of the motors provided for the upper and lower conveying units  70 , since a control program in the case of using the conveying unit  70  for a supply application and a control program in the case of using the conveying unit  70  for a winding application are different, either control is performed by sequentially referring to the application selection information stored in the RAM  203 . 
     (Operation Sequence in Sheet Supply) 
     With reference to  FIG. 5 , a description will be given of a flow of an operation sequence in sheet supply according to a first embodiment. In the following description, signs in parentheses indicate numbers of steps in the flow shown in the figure. A description will be given based on the following: rotation in the sheet supply direction is defined as forward rotation and rotation in a direction opposite to the forward direction is defined as backward rotation. 
     The spool member  2  is inserted into the paper core of the roll sheet  1  and set on the conveying unit  70  (S 1 ). The spool presence/absence detection sensor  32  provided for the spool holder  31  detects the presence of the spool member  2  (S 2 ). With the detection of the presence of the spool member  2 , a message of the detection is announced on the operation panel. If the user inserts a leading end  9  of the sheet  1  into the conveying guide  8 , the sheet leading end detection sensor  301  detects the leading end  9  of the sheet  1  (S 3 ). Then, the auxiliary mechanism  200  rotates by the pressure drive motor  33  and presses the roll sheet  1 . 
     In this example, driving the pressure drive motor  33  in the forward direction causes the auxiliary mechanism  200  to operate in a direction in which the auxiliary mechanism  200  comes closer to the roll sheet  1 , and driving the pressure drive motor  33  in the backward direction causes the auxiliary mechanism  200  to operate in a direction in which the auxiliary mechanism  200  is separated from the roll sheet  1 . The roll outer diameter detection sensor  5   c  detects a distance between a surface of the roll sheet  1  and the auxiliary mechanism  200  acting as a pressure mechanism, and the pressure drive motor  33  stops at an appropriate pressing position. Controlling a direction and an amount of the driving of the pressure drive motor  33  can change a pressing force of the auxiliary mechanism  200  against the roll sheet  1 . That is, the auxiliary mechanism  200  can be in contact with or be separated from the roll sheet  1 , and various levels of the pressing force when the auxiliary mechanism  200  is in contact with the roll sheet  1  can be set. States of the pressing can be arbitrarily changed in the middle of the sequence according to the situation. 
     Then, the printing apparatus performs a sheet conveying operation. More specifically, driving of the roll drive motor  34  and the conveying roller drive motor  35  in the forward rotation direction is started, and sheet conveyance is started (S 5 ). The sheet leading end detection sensor  12  detects the leading end  9  of the sheet  1  which has been drawn from the roll portion of the roll sheet  1  (S 6 ). The sheet  1  is then fed by a predetermined amount and delivered to pass the conveying roller  10  (S 7 ). Then, the auxiliary mechanism  200  is separated from the roll sheet  1 , and at the same time, a nip pressure of the conveying pinch roller  11  with respect to the conveying roller  10  is set to a low nip pressure which is lower than a normal nip pressure, that is, a nip pressure used in printing (S 8 ). Then, skew of the sheet  1  is corrected by repeating back-feeding and feeding of the sheet  1  (S 9 ). 
     It should be noted that in the present specification, the term feeding indicates conveyance in a sheet conveying direction while printing of the sheet is performed (corresponding to a supply direction), whereas the term back-feeding indicates conveyance in a direction opposite to the sheet conveying direction while printing of the sheet is performed (corresponding to a winding-back direction). 
     Then, while back-feeding the sheet  1 , a sensor (not shown) captures a position of the leading end  9  of the sheet  1  and detects a skew amount (S 10 ), and the sheet  1  is stopped such that the leading end  9  of the sheet  1  is located at a standby position before printing is started (S 11 ). Then, a nip pressure of the conveying pinch roller  11  with respect to the conveying roller  10  is returned to a normal nip pressure (S 12 ), and the supply operation is finished (S 13 ). 
     (Operation Sequence in Printing in the First Usage Form) 
     Next, with reference to  FIG. 6 , a description will be given of a flow of an operation sequence in printing in the first usage form according to the first embodiment. In the following description, signs in parentheses indicate numbers of steps in the flow shown in the figure. It should be noted that since the sequence is started from the operation end state in sheet supply (S 13  in  FIG. 5 ) as described above, the auxiliary mechanism  200  is being separated from the roll sheet  1 , and a nip pressure of the conveying pinch roller  11  with respect to the conveying roller  10  is a normal nip pressure. 
     If print data is received from a PC or the like (S 14 ), driving of the conveying roller drive motor  35  in the forward rotation direction is started, and sheet conveyance is started (S 15 ). The leading end  9  of the sheet at the standby position is fed to a position immediately below the print head  15  (S 16 ). Then, the print head  15  scans the sheet in the width direction and ejects ink to perform printing (S 17 ). 
     More specifically, after the print head  15  scans the sheet in a forward direction to perform printing corresponding to one line, the conveying roller  10  feeds the sheet  1  by a predetermined amount, and then the print head  15  scans the sheet  1  in a backward direction to perform printing corresponding to one line. In this manner, printing is performed by repeating the forward and backward operations of the print head  15  and the feeding operation of the conveying roller  10  while conveying the sheet  1  to the downstream side. At this time, along with the feeding operation by the conveying roller  10 , the roll drive motor  34  (driving unit) is controlled to be driven in the backward rotation direction. In the control of the roll drive motor  34 , a driving force is suppressed with current restriction, and accordingly, the sheet  1  is pulled by the conveying roller  10  with a force which is equal to or greater than the driving force of the conveying roller  10 . Such control is performed so as to apply an appropriate back tension to the roll sheet  1  and achieve stable conveyance without a sag. 
     If printing is finished (S 18 ), the conveying roller  10  feeds the sheet  1  until a trailing end of a printed portion comes to a cut position of the cutter  16  (S 19 ), and a cutter drive motor (not shown) activates the cutter  16  to perform cutting (S 20 ). A cut printed material is stored in the basket unit  62 . The sheet  1  that is left on the printing apparatus side is back-fed by a predetermined amount by the conveying roller  10  (S 21 ), and a new leading end  9  of the sheet  1  produced by the cutting is returned to a print start standby position, and the printing apparatus enters a standby state (S 22 ). 
     (Operation Sequence in Sheet Winding-Back) 
     With reference to  FIG. 7 , a description will be given of an example of a flow of an operation sequence to wind back the sheet  1 . In the following description, signs in parentheses indicate numbers of steps in the flow shown in the figure. It should be noted that the term winding-back as used in the present specification indicates an operation of back-feeding the sheet  1  from a state in which the leading end  9  of the sheet  1  is located near the conveying roller  10  (for example, the standby state as described in S 13  of  FIG. 5  and S 22  of  FIG. 6 ) to a state in which the leading end  9  of the sheet  1  comes near a supply port of the conveying unit  70 . 
     First, the auxiliary mechanism  200  presses the roll sheet  1  (S 23 ). This is to avoid loosening of the winding of the roll sheet  1  in the conveying unit  70  as a supply unit. In this state, the roll drive motor  34  and the conveying roller drive motor  35  are driven in the backward rotation direction at the same time (S 24 ) to back-feed the sheet  1 . After a while, the leading end  9  of the sheet  1  passes the detection position of the sheet leading end detection sensor  12  (S 25 ), and accordingly, driving of the conveying roller drive motor  35  is stopped (S 26 ). The roll drive motor  34  is kept driven, and the sheet  1  is further back-fed. Then, the leading end  9  of the sheet  1  passes the detection position of the sheet leading end detection sensor  301  (S 27 ). After that, the roll drive motor  34  is stopped, and the winding-back operation is finished (S 28 ). 
     It should be noted that in a case where the sheet  1  is wound up to the end for the purpose of replacement of the roll sheet or the like, the roll drive motor is kept driven even after the sheet  1  passes the detection position of the sheet leading end detection sensor  301 , and the sheet  1  is back-fed until the leading end  9  of the sheet  1  is released from the conveying guide  8 . 
     Meanwhile, for example, in a case where the roll sheet used for printing is switched between the upper and lower units, the sheet  1  does not need to be wound up to the end. More specifically, after the leading end  9  of the sheet  1  passes the detection position of the sheet leading end detection sensor  301 , the roll drive motor  34  is stopped immediately, and the leading end  9  of the sheet  1  is made to wait close to the sheet leading end detection sensor  301 . At this time, the auxiliary mechanism  200  maintains a pressing state with respect to the roll sheet  1  to prevent the sheet  1  from dropping from the conveying guide  8  under its own weight. 
     To avoid loosening of the winding of the roll sheet  1  and to prevent the sheet  1  from dropping from the conveying guide  8 , pressing forces of the auxiliary mechanisms  200  in sheet supply may be the same or different. For example, by setting a pressing force for avoiding loosening of the winding and dropping to a pressing force that is greater than that in sheet supply, it is possible to increase an effect of prevention of dropping or the like without affecting precision of sheet conveyance in supplying and damage to the surface of the roll sheet. 
     A description has been given of the case of the first usage form in which both of the upper and lower conveying units  70  are used as supply units. Next, a description will be given of the case of a second usage form in which one of the conveying units  70  is used as a winding unit. 
     (Second Usage Form) 
     With reference to the drawings, a description will be given of the case where the upper conveying unit  70  is used as a supply unit and the lower conveying unit  70  is used as a winding unit (second usage form). It should be noted that a description of the configuration and the operation that are the same as those of the above-described first usage form will be omitted. 
     In  FIG. 9 , in the case of using the lower conveying unit  70  as a winding unit, the paper core  17  for sheet winding is attached to the spool member  2 , and the leading end  9  of the sheet  1  is fixed to the paper core  17  by using a tape or the like, and the sheet  1  that has been conveyed is wound up. Since the movable guide member  68  and the basket unit  62  are obstruction in the state shown in  FIG. 2A , they are used in the positions at which they are housed. That is, in the second usage form, the position detection sensor  69  of the movable guide member  68  is ON and the position detection sensor  67  of the basket unit  62  is OFF. 
     In this example, in a case where the conveying unit  70  is used as a supply unit, the auxiliary mechanism  200  serves as a “sheet supply auxiliary mechanism” which assists supply of a sheet. Meanwhile, in a case where the conveying unit  70  is used as a winding unit, the auxiliary mechanism  200  is pressed against or separated from the surface of the wound sheet  1  in setting the sheet on the paper core, in printing, or in end processing, so as to serve as a “sheet winding auxiliary mechanism” which assists winding of a sheet. In the present specification, depending on application of the conveying unit  70 , that is, depending on the usage form, the auxiliary mechanism  200  is also referred to as a supply auxiliary mechanism  200  or a winding auxiliary mechanism  200 . 
     (Configuration to Set the Paper Core) 
     With reference to  FIGS. 10A to 11B , a description will be given of a configuration of setting the paper core  17  for sheet winding on the printing apparatus. 
       FIG. 10A  is a front view of the spool member  2  in a disassembled state.  FIG. 10B  is a front view of the spool member  2  in an assembled state. A difference between the configuration of the spool member  2  in supplying as described with reference to  FIGS. 3A to 3C  and the configuration of the spool member  2  for winding is that the supply flange attachment  26  is not provided in the configuration of the spool member  2  for winding. That is, as described above, since the supply flange attachment  26  can be detached from the reference spool flange  23  and the non-reference spool flange  24 , the supply flange attachment  26  is detached in the case of the purpose of winding. 
     In  FIGS. 11A and 11B , the spool member  2  in supplying and the spool member  2  in winding are arranged in a vertical direction and compared. 
     As shown in  FIG. 11A , the supply flange attachment  26  is attached to the flange in supplying. An end surface of the supply flange attachment  26  is a flat surface and is caused to abut on the end portion of the roll sheet  1  to be set so as to position the roll sheet  1  in the width direction. A side of the non-reference spool flange  24  does not always need to be a flat surface, and the spool member  2  may be used with the supply flange attachment  26  detached. 
     On the other hand, as shown in  FIG. 11B , end surfaces of the flanges in winding, that is, end surfaces of the reference spool flange  23  and the non-reference spool flange  24 , are arranged with a distance that is greater than the width of the sheet  1 , and are tapered. Therefore, skew of the sheet  1  that is wound around the paper core  17  can be allowed to some extent. It should be noted that the configuration other than this point is the same as the configuration in supplying which is described with reference to  FIG. 3 . 
     (Operation Flow in Paper Core Setting) 
     With reference to  FIGS. 12 and 13 , a description will be given of the operation of attaching the leading end  9  of the sheet  1  to the paper core  17  for sheet winding.  FIG. 12  is a schematic view of the printing apparatus in the second usage form.  FIG. 13  is a flow of an operation sequence when the paper core for sheet winding is set on the printing apparatus. In the following description, signs in parentheses indicate numbers of steps in the flow shown in the figure. A description will be given of the flow starting from the standby state after the sheet  1  is supplied from the upper supply unit  70  in accordance with step S 1  through step S 13  in the flow described with reference to  FIG. 5 . 
     The spool member  2  is inserted into the paper core  17  and set on the lower conveying unit  70  (R 1 ). The spool presence/absence detection sensor  32  provided for the spool holder  31  detects the spool member  2  (R 2 ). The pressure drive motor  33  is driven in the backward direction and the winding auxiliary mechanism  200  is separated from the spool member  2  (R 3 ). Then, the printing apparatus performs the conveying operation of the sheet  1  supplied from the roll sheet  1  of the upper conveying unit  70 . The conveying roller drive motor  35  is driven in the forward rotation direction (R 4 ), and the sheet  1  is fed by the conveying roller  10  by a predetermined amount to reach near the paper core  17  attached to the lower conveying unit  70  (R 5 ). Then, with a user operation, the leading end  9  of the sheet  1  is inserted into the space between the paper core  17  and the winding auxiliary mechanism  200  that is separated from the paper core  17  (R 6 ). 
     After that, if a trigger is generated by the operation on the operation panel  20  by the user, the pressure drive motor  33  of the lower conveying unit  70  is driven in the forward direction, and the winding auxiliary mechanism  200  presses the leading end  9  of the sheet  1  against the paper core  17  (R 7 ). In this state, the conveying roller drive motor  35  is driven in the backward rotation direction, and at the same time, the roll drive motor  34  of the lower conveying unit  70  is driven in the forward rotation direction (R 8 ). 
     That is, at this time, the two motors, namely, the conveying roller drive motor  35  and the roll drive motor  34  of the lower conveying unit  70 , rotate in opposite directions. Since a friction force generated between the conveying roller  10  and the sheet  1  is set sufficiently greater than a friction force generated between the paper core  17  and the sheet  1 , the sheet  1  is back-fed by a predetermined amount along with the backward rotation of the conveying roller  10  (R 9 ). 
     The reason why the lower roll drive motor  34  is driven in the forward rotation direction is that a tension is applied to the sheet  1  by feed rotation of the paper core  17  with respect to the back-feeding operation by the conveying roller  10 . By back-feeding the sheet  1  while the tension is applied, a warp of the sheet  1  to be wound around the paper core  17  is removed, and skew is corrected. 
     Then, in this state, the leading end  9  of the sheet  1  is fixed to the paper core  17  by using a tape or the like (R 10 ). 
     By the way, a conventional winding apparatus does not have a mechanism like the winding auxiliary mechanism  200  of the present embodiment. Accordingly, in a case where the user fixes the leading end  9  of the sheet  1  to the paper core  17 , the user himself/herself needs to apply a tension to the sheet by hand and carefully fix the sheet  1  straight by his/her own sense. That is, in the present embodiment, the winding auxiliary mechanism  200  mitigates the inconveniences of the conventional operation flow and contributes to the reduction of the load on the user. 
     As described above, the operation of attaching the leading end  9  of the sheet  1  to the paper core  17  for sheet winding (paper core setting operation) is completed, and the printing apparatus enters a standby state (R 11 ). 
     (Operation Sequence in Printing in the Second Usage Form) 
     With reference to  FIG. 14 , a description will be given of a flow of an operation sequence in printing in the second usage form according to the first embodiment, that is, when winding is performed while printing. In the following description, signs in parentheses indicate numbers of steps in the flow shown in the figure. 
     If print data is received from a PC or the like (R 12 ), both the conveying roller drive motor  35  and the roll drive motor  34  of the lower conveying unit  70  are driven in the forward rotation direction (R 13 ), and conveyance of the sheet  1  is started. A print start position of the sheet  1  located on the standby position is fed to the position immediately below the print head  15  (R 14 ). Then, the pressure drive motor  33  of the lower conveying unit  70  is driven in the backward direction, and the winding auxiliary mechanism  200  is separated (R 15 ). Then, the print head  15  scans the sheet in the width direction and ejects ink to perform printing (R 16 ). 
     With respect to the printing, the operation of the print head  15 , the operation of the conveying roller  10 , and the back tension applying operation of the roll drive motor  34  of the upper conveying unit  70  which supplies the sheet  1  are performed as described in step S 17  of  FIG. 6 . 
     With respect to winding, the roll drive motor  34  of the lower conveying unit  70  for winding the sheet  1  that has passed the printing unit operates with the conveying roller  10 . If the leading end of the printed sheet  1  is conveyed to the position of the lower conveying unit  70 , the user stops the operation of the lower roll drive motor  34  by a pause button (not shown) or the like. At that time, the printing operation is continued without being stopped. In a state in which the winding operation is stopped, the user fixes the leading end of the sheet  1  to the paper core (R 17 ), and after the paper core setting operation is finished, the user restarts the winding operation of the lower roll drive motor  34  by pressing the pause button again. At this time, the roll drive motor  34  is controlled by current restriction so as not to pull the sheet  1  with a predetermined torque (tension) or greater. This is because if a tension more than necessary is generated, conveyance precision is affected. This control achieves stable conveyance. 
     After printing is finished, in a case where winding is used following the printing, the printing apparatus enters the standby state accordingly (R 18 ). 
     (Operation Sequence of Sheet End Processing) 
     With reference to  FIG. 15 , a description will be given of a flow of an operation sequence of sheet end processing in winding according to the first embodiment. In the following description, signs in parentheses indicate numbers of steps in the flow shown in the figure. 
     If a trigger of the end processing is generated by the operation on the operation panel  20  by the user, the conveying roller drive motor  35  and the roll drive motor  34  of the lower conveying unit  70  are driven in the forward rotation direction (R 19 ), and feeding by a predetermined amount is performed (R 20 ). Then, the pressure drive motor  33  of the lower conveying unit  70  is driven in the forward direction, and the winding auxiliary mechanism  200  is pressed against the surface of the sheet (roll sheet)  1  that is wound in a roll (R 21 ). 
     At this time, if the rollers  6  and  7  of the winding auxiliary mechanism  200  come into contact with a printed portion, there is a possibility of ink transfer or the like. Therefore, in the feeding operation performed in step R 20 , it is preferable to wind and convey the sheet  1  until the printed portion comes to the downstream side at which the printed portion does not come into contact with the rollers  6  and  7 . Alternatively, if the printed portion comes into contact with the rollers  6  and  7 , a technique may be used to press the sheet  1  after a sufficient drying time or to apply fluorine coating or the like to the surfaces of the rollers to avoid transfer. 
     In either case, the cutter  16  is activated by the cutter drive motor (not shown) to cut the sheet  1  in the state in which the winding auxiliary mechanism  200  is pressed against the surface of the sheet (roll sheet)  1  wound in a roll (R 22 ). It should be noted that generally, in cutting, the user holds by hand the trailing end of the sheet (roll sheet)  1  which is wound up by the conveying unit  70  acting as a winding unit so as to prevent the trailing end of the sheet from dropping from the roll portion of the roll sheet after the cutting. 
     After that, with the operation of the operation panel  20  or a button or the like by the user, the trailing end portion of the sheet  1  on the winding unit is wound up (R 23 ). The trailing end of the sheet  1  is fixed to the roll portion of the wound roll sheet  1  by using a tape or the like, and the end processing is finished (R 24 ). 
     As described above, in the first embodiment, in step R 21  and the subsequent steps, the winding auxiliary mechanism  200  presses the surface of the roll sheet  1 . Accordingly, during the operations from step R 22  to step R 24 , there is no possibility that the wound roll sheet  1  is loosened even if there is a sag between the trailing end portion of the sheet  1  held by the user&#39;s hand and a portion pressed by the winding auxiliary mechanism  200 . 
     The conventional winding unit does not have a mechanism like the winding auxiliary mechanism  200 . Therefore, unless the wound roll sheet  1  is held carefully not to produce a sag after cutting, there is a possibility that the wound roll sheet  1  is loosened. Once the wound roll sheet  1  is loosened, then, the printed surface may be scratched to have an abrasion when wound up tight. That is, in the first embodiment, the inconveniences of the conventional operation sequence are reduced by the winding auxiliary mechanism  200 , and at the same time, the winding auxiliary mechanism  200  contributes to improvement of the print quality. 
     According to the configuration described above, it is possible to provide the printing apparatus having the sheet winding function in which a load on the user is reduced. 
     In the above-described first embodiment, the supply auxiliary mechanism  200  and the winding auxiliary mechanism  200  automatically perform the separation operation and the contact operation. Meanwhile, in a second embodiment, a supply auxiliary mechanism  200  and a winding auxiliary mechanism  200  do not perform a separation operation, but maintain a contact state with respect to the outer periphery of a roll sheet  1  (or a paper core  17 ). A description will be given of a flow of an operation sequence according to the second embodiment. It should be noted that a description of the configuration and the operation that are the same as those of the above-described first embodiment will be omitted. 
     (First Usage Form) 
     First, a description will be given of a case where both of upper and lower conveying units  70  are used as supply units in the second embodiment (a first usage form according to the second embodiment). 
     (Operation Sequence in Sheet Supply According to the Second Embodiment) 
       FIG. 17  shows an example of a flow of an operation sequence in sheet supply according to the second embodiment. A description will be given of a difference from the flow in the first embodiment shown in  FIG. 5 . The same signs in  FIGS. 5 and 17  indicate the same steps, so a description thereof will be omitted. 
     In the second embodiment, a series of the steps (S 1  to S 3 ) for setting a sheet by a user is the same as the one of the first embodiment described in  FIG. 5 . 
     In the first embodiment, next, the auxiliary mechanism  200  is rotated by the pressure drive motor  33  to press the roll sheet  1  (S 4 ). Meanwhile, the second embodiment does not include a step corresponding to step S 4 . More specifically, in the first embodiment, the supply auxiliary mechanism  200  and the roll sheet  1  come into contact with each other when the roll sheet  1  is set on the conveying unit  70  in step S 1 , whereas in the second embodiment, this contact state is maintained in step S 1  and the subsequent steps. 
     It should be noted that the essence of the present embodiment is that in a series of steps, the supply auxiliary mechanism  200  and the roll sheet  1  are not separated from each other. This can prevent loosening of the winding of the roll and reduce a load on the user. Accordingly, in the second embodiment, while the contact state is maintained, it is possible to arbitrarily change a pressing force against the roll sheet by rotating the auxiliary mechanism  200  by a pressure drive motor  33  according to the situation. 
     A series of the steps from starting sheet conveyance (S 5 ) by a roll drive motor  34  and a conveying roller drive motor  35  to sheet leading end detection (S 6 ) and sheet delivery (S 7 ) in the second embodiment is the same as the one in the first embodiment described in  FIG. 5 . 
     In the first embodiment, after the sheet delivery (S 7 ), the supply auxiliary mechanism  200  pressing the roll sheet  1  is released by separation before the nip pressure of the conveying pinch roller  11  with respect to the conveying roller  10  is set to a low nip pressure which is lower than a normal nip pressure used in printing (S 8 ). Meanwhile, in the second embodiment, without releasing the pressing by separating the supply auxiliary mechanism  200  from the sheet  1 , a nip pressure is set to a low nip pressure (S 35 ). That is, as described above, in the second embodiment, the contact state between the supply auxiliary mechanism  200  and the roll sheet  1  is maintained. 
     A series of the subsequent steps, from skew correction (S 9 ), skew amount detection (S 10 ), stopping on the standby position (S 11 ), changing a nip pressure to a normal nip pressure (S 12 ), to end of the supply operation (S 13 ), is the same as the one in the first embodiment described in  FIG. 5 . 
     (Operation Sequence in Printing in the First Usage Form According to the Second Embodiment) 
     The flow of the first embodiment shown in  FIG. 6  by itself can be applied to a flow of an operation sequence in printing in the first usage form according to the second embodiment. Also in the second embodiment, like the first embodiment, since the operation sequence in printing is started from the above-described state (step S 13 ) in which the operation in supplying is finished, a nip pressure of the conveying pinch roller  11  with respect to the conveying roller  10  at the time of starting the operation is a normal nip pressure. Meanwhile, unlike the first embodiment, since the second embodiment does not include a step of releasing the pressing of the roll sheet  1  by the supply auxiliary mechanism  200 , the printing operation is performed in the pressing state. 
     (Operation Sequence in Sheet Winding-Back According to the Second Embodiment) 
       FIG. 18  is a flow of an operation sequence of winding back the leading end  9  of the sheet  1  according to the second embodiment. A description will be given of a difference from the flow in the first embodiment shown in  FIG. 7 . The same signs in  FIGS. 7 and 18  indicate the same steps, so a description thereof will be omitted. 
     In the first embodiment shown in  FIG. 7 , to start a winding-back operation, first, the auxiliary mechanism  200  is pressed against the roll sheet  1  (S 23 ). This is performed to avoid loosening of the winding of the roll sheet  1  on the conveying unit  70  as a supply unit. 
     Meanwhile, the flow in the second embodiment shown in  FIG. 18  does not include a step corresponding to step S 23 . As described above, this is because in the second embodiment, the printing operation is performed in the state in which the supply auxiliary mechanism  200  presses the roll sheet  1 , without involving the releasing operation, and the pressing state is maintained at the time of start of the winding-back. Therefore, also in the second embodiment, in performing the winding-back operation, loosening of the winding of the roll sheet  1  on the conveying unit  70  as a supply unit is avoided. 
     The subsequent steps (S 24  to S 28 ) in the second embodiment are the same as those of the first embodiment described in  FIG. 7 . 
     A description has been given of the first usage form according to the second embodiment in which both of the upper and lower conveying units  70  are used as supply units. Next, a description will be given of the case of a second usage form in which one of the conveying units  70  is used as a winding unit. 
     (Second Usage Form) 
     Next, a description will be given of the case of using the upper conveying unit  70  as a supply unit and the lower conveying unit  70  as a winding unit in the second embodiment (a second usage form according to the second embodiment). It should be noted that a description of the configuration and the operation that are the same as those of the above-described first embodiment and the first usage form of the second embodiment will be omitted. 
     (Operation Flow in Paper Core Setting in the Second Usage Form According to the Second Embodiment) 
       FIGS. 12 and 19  illustrate an operation of attaching the leading end  9  of the sheet  1  to the paper core  17  for sheet winding in the second usage form according to the second embodiment.  FIG. 12  is a schematic view of a printing apparatus in the second usage form.  FIG. 19  shows an operation flow when the paper core for sheet winding is set on the printing apparatus. The operation flow in paper core setting is started from the standby state after the sheet  1  is supplied from the upper supply unit  70  in accordance with step S 1  through step S 13  in the operation sequence in sheet supply shown in  FIG. 17 . 
     A description will be given of a difference between the flow in the second embodiment shown in  FIG. 19  and the flow in the first embodiment shown in  FIG. 13 . The same signs in  FIGS. 13 and 19  indicate the same steps, so a description thereof will be omitted. 
     A series of steps from paper core setting (R 1 ) to spool detection (R 2 ) in the second embodiment is the same as the one of the first embodiment described in  FIG. 13 . 
     After it is detected that there is a spool (R 2 ), in the first embodiment, the winding auxiliary mechanism  200  is separated from the paper core  17  (R 3 ). Meanwhile, the second embodiment does not include the separation step corresponding to step R 3 , and thus the contact state of the winding auxiliary mechanism  200  with respect to the paper core  17  is maintained in the second embodiment. 
     A series of the subsequent steps, from driving the conveying roller (R 4 ), feeding the sheet by the predetermined amount (R 5 ), to inserting the sheet leading end into the space between the paper core and the winding auxiliary mechanism (R 6 ), is the same as the one in the first embodiment described in  FIG. 13 . 
     Next, in the first embodiment, the winding auxiliary mechanism  200  is pressed against the paper core  17  (the sheet  1  eventually) (R 7 ). Meanwhile, the second embodiment does not include the separation step corresponding to step R 7 . This is because since the contact state of the winding auxiliary mechanism  200  with respect to the paper core  17  is maintained in the second embodiment, there is no need to have a pressing operation again. 
     A series of steps, from driving the driving motors  34  and  35  (R 8 ), back-feeding the sheet  1  by the predetermined amount (R 9 ), fixing the leading end of the sheet to the paper core  17  (R 10 ), completing the attachment operation, to entering the standby state (R 11 ), is the same as the one in the first embodiment. 
     (Operation Sequence in Printing in the Second Usage Form According to the Second Embodiment) 
       FIG. 20  shows an example of a flow of an operation sequence in the case of printing in the second usage form according to the second embodiment, that is, in the case of printing while winding. A description will be given of a difference from the flow in the first embodiment shown in  FIG. 14 . The same signs in  FIGS. 14 and 20  indicate the same steps, so a description thereof will be omitted. 
     A series of steps from receiving print data (R 12 ), driving the drive motors  34  and  35  (R 13 ), to feeding the sheet  1  by the predetermined amount (R 14 ) is the same as the one in the first embodiment described in  FIG. 14 . 
     After the sheet is fed by the predetermined amount (R 14 ), in the first embodiment, the winding auxiliary mechanism  200  is separated from the paper core  17  (the sheet  1  eventually) (R 15 ). Meanwhile, the second embodiment does not include the separation step corresponding to step R 3 . Thus, the contact state of the winding auxiliary mechanism  200  with respect to the paper core  17  (sheet  1 ) is maintained in the second embodiment. 
     A series of the subsequent steps, from printing (R 16 ), fixing the sheet leading end to the paper core (R 17 ), to finishing printing to entering the standby state (R 17 ), is the same as the one in the first embodiment described in  FIG. 14 . 
     (Operation Sequence of Sheet End Processing in the Second Usage Form According to the Second Embodiment) 
       FIG. 21  shows an example of a flow of an operation sequence of sheet end processing according to the second embodiment. A description will be given of a difference from the flow of the first embodiment shown in  FIG. 15 . The same signs in  FIGS. 15 and 21  indicate the same steps, so a description thereof will be omitted. 
     A difference between the first embodiment and the second embodiment is whether to include the step of pressing the winding auxiliary mechanism  200  against the roll sheet  1  (R 21 ) before the step of cutting the sheet  1  by activating the cutter  16  by the cutter drive motor (R 22 ). The first embodiment shown in  FIG. 15  includes the pressing step (R 21 ), whereas the second embodiment shown in  FIG. 21  does not include the pressing step (R 21 ). This is because since the winding auxiliary mechanism  200  is consistently kept into contact with and pressed against the roll sheet  1  in and after the setting operation of the paper core  17 , there is no need to perform the pressing step (R 21 ) again. 
     As described above, in the present embodiment, the supply auxiliary mechanism  200  and the winding auxiliary mechanism  200  are not separated from the roll sheet  1  (or the outer periphery of the paper core  17 ), but the contact state is maintained. It is possible to perform their respective operations even in this state without problems. 
     According to the configuration described above, it is possible to provide the printing apparatus having the sheet winding function in which a load on the user is reduced. 
     In the above first embodiment, the supply auxiliary mechanism  200  and the winding auxiliary mechanism  200  automatically perform the separation operation and the contact operation. Meanwhile, in the above second embodiment, the supply auxiliary mechanism  200  and the winding auxiliary mechanism  200  maintain the contact state without being separated from the roll sheet  1  or the paper core  17 . Meanwhile, in a third embodiment, a supply auxiliary mechanism  200  and a winding auxiliary mechanism  200  do not automatically perform a separation operation and a contact operation, but a user manually performs the separation operation and the contact operation. This will be described. A description of the configuration and the operation that are the same as those of the above-described first and second embodiments will be omitted. 
     (Second Usage Form According to a Third Embodiment) 
       FIG. 22  is a view showing a configuration of a printing apparatus in a second usage form according to a third embodiment. In  FIG. 22 , a lever  71  is a lever with which a user can manually cause the supply auxiliary mechanism  200  and the winding auxiliary mechanism  200  to be separated from or to be in contact with (separation/contact) a roll sheet  1  or a paper core  17  for sheet winding from the outer periphery side thereof. Although not shown in the figure, there is a sensor that can detect a separation/contact state (e.g., a pressing force). If the printing apparatus body is ON, it is possible to know the states of the auxiliary mechanisms  200 . 
     To have the user operate to change the separation/contact state of the auxiliary mechanism  200  (change in a pressing force), the operation of the printing apparatus body is paused, and a message is displayed on an operation panel  20  so that the user is prompted for an operation. If the user checks the display and changes the state of the lever  71 , a sensor (not shown) detects the change in the state, and the printing apparatus body moves to the next operation. 
     According also to the configuration of the present embodiment, it is possible to provide the printing apparatus having the sheet winding function in which a load on the user is reduced. 
     As described above, in the first embodiment, a description has been given of the case of the operation sequences in which the supply auxiliary mechanism  200  and the winding auxiliary mechanism  200  automatically perform the separation operation and the contact operation. In the second embodiment, a description has been given of the operation sequences in which the supply auxiliary mechanism  200  and the winding auxiliary mechanism  200  do not perform the separation operation but maintain the contact state. In the present invention, there is no problem, in terms of functions, in keeping the supply auxiliary mechanism  200  and the winding auxiliary mechanism  200  in the contact state. Further, during the operations in supplying, printing, winding, setting a roll sheet or a paper core for winding, end processing, and the like, the separation/contact state may be changed automatically or manually as necessary. This operation is not limited. 
     In the present invention, any pressing force of the auxiliary mechanism  200  with respect to the roll sheet  1  (a separation state or a contact state and a level of a pressing force in the contact state) may be set according to the situation. 
     For example, after a leading end of a sheet drawn from a roll sheet is threaded through a nip of a conveying roller in front of a printing unit, using a low pressing force in the supply unit that is lower than a pressing force for drawing the leading end of the sheet can preferably correct skew of the sheet. 
     Further, while printing is performed, using a relatively low pressing force in the supply unit and the winding unit can achieve stable conveyance without producing a tension more than necessary on the sheet, and damage to the roll sheet can be reduced. In addition, separating the auxiliary mechanism at the same time can protect the auxiliary mechanism from ink transfer or the like from the wound sheet. 
     When the sheet is cut, using a relatively large pressing force can prevent a warp of the sheet by releasing a tension by cutting and loosening of the winding of the roll sheet. Furthermore, using a relatively small pressing force in back-feeding to fix and attach the leading end of the sheet to the paper core for winding in the winding unit can preferably correct skew of the sheet. 
     The pressing force may be set in two levels (low and high). To obtain a preferable effect according to the situation, the pressing force may be set in three or more levels. Further, the pressing force of the supply auxiliary mechanism and the pressing force of the winding auxiliary mechanism may be set independently, and these pressing forces may be the same or different. 
     In the present embodiment, the printing apparatus has two conveying units, but the present invention may be applied also to a printing apparatus having three or more conveying units. Furthermore, the present invention is not limited to the printing apparatus, and can be applied generally to a winding apparatus for winding an article in the form of a sheet. 
     In the above first embodiment, the supply auxiliary mechanism  200  and the winding auxiliary mechanism  200  automatically perform the separation operation and the contact operation. In the above second embodiment, the supply auxiliary mechanism  200  and the winding auxiliary mechanism  200  maintain the contact state without being separated from the roll sheet  1  or the paper core  17 . In the above third embodiment, the supply auxiliary mechanism  200  and the winding auxiliary mechanism  200  do not automatically perform the separation operation and the contact operation, but the user manually performs the separation operation and the contact operation. 
     In an operation sequence in printing according to a fourth embodiment, switching between separation and contact of an auxiliary mechanism  200  is performed automatically or manually according to at least one of a sheet type and a winding direction. A description will be given below. 
     For example, in the case of an inwardly wound roll sheet which has a high stiffness and is wound to have a printed surface inwardly, since the roll is highly stiff and is wound in a direction opposite to the curl of the roll, the normal winding results in loosening of the winding and an abrasion. To solve this problem, it is needed to wind up the sheet with a greatly increased tension for winding. However, if a sheet  1  is pulled with a predetermined tension or greater in winding, conveyance precision may be affected and stable conveyance may not be achieved. To avoid this, loosening of the winding can be prevented by bringing the auxiliary mechanism  200  into contact with the sheet  1  in winding and a rotation load can be reduced by forming a pressing portion as a rotor such as a roller. This allows winding without loosening and without increasing a tension in winding. This configuration can achieve normal winding without affecting the conveyance precision or increasing the cost of motors. 
     In the case of a sheet having a low stiffness, loosening of the winding does not occur since the curl of the sheet is small. There is also a case where bringing the auxiliary mechanism  200  into contact with the sheet may produce a trace due to pressure and contact by rollers. In this case, the auxiliary mechanism  200  is separated and used. 
     Further, in the case of an outwardly wound roll sheet which is wound to have a printed surface outwardly, since a curl direction of the sheet and a winding direction of the roll match, loosening of the winding is not likely to occur even without bringing the auxiliary mechanism  200  into contact with the sheet. Further, in the case of a sheet having a lower print drying performance, since the printed surface faces outwardly, an adverse effect such as transfer to the roller or the like may occur by bringing the auxiliary mechanism  200  into contact with the sheet. Also in this case, winding is performed by separating the auxiliary mechanism  200 . 
     As described above, automatically or manually switching between the separation and the contact of the auxiliary mechanism  200  according to the conditions such as a sheet type and a winding direction can maintain conveyance precision and handle more sheets. 
     Regarding setting of the separation and the contact of the auxiliary mechanism  200 , a predetermined value is set in advance for each sheet based on a curl property of a sheet, a transfer property of a print, and the like. In a case where the set value is different from a value intended by a user, the setting may be changed manually. 
       FIG. 23  shows a flow of an operation sequence in printing, that is, in printing while winding (second usage form) according to the fourth embodiment. In the following description, signs in parentheses indicate numbers of steps in the flow shown in the figure. 
     If print data is received from a PC or the like (R 12 ), both the conveying roller drive motor  35  and the roll drive motor  34  of the lower conveying unit  70  are driven in the forward rotation direction (R 13 ), and conveyance of the sheet  1  is started. The leading end  9  of the sheet  1  located on the standby position is fed to the position immediately below the print head  15  (R 14 ). Then, a pressure drive motor  33  of the lower conveying unit  70  is driven in a direction set based at least on one of a sheet type and a winding direction, and the winding auxiliary mechanism  200  is separated from or is kept into contact with the roll sheet  1  (R 46 ). Then, the print head  15  scans the sheet in the width direction and ejects ink to perform printing (R 16 ). 
     Here,  FIGS. 14, 20, and 23  are compared. In the first embodiment shown in  FIG. 14 , the operation of separating the auxiliary mechanism  200  (R 15 ) is performed between step R 14  and step R 16 . In the second embodiment shown in  FIG. 20 , the operation of separating the auxiliary mechanism  200  is not performed between step R 14  and step R 16 , and the contact state is maintained. Meanwhile, in the fourth embodiment, as shown in  FIG. 23 , the separation state or the contact state of the auxiliary mechanism  200  is set or manually switched (R 46 ). This allows preferable printing and sheet winding according to the condition. 
     In the above first embodiment, the supply auxiliary mechanism  200  and the winding auxiliary mechanism  200  automatically perform the separation operation and the contact operation. In the above second embodiment, the supply auxiliary mechanism  200  and the winding auxiliary mechanism  200  maintain the contact state without being separated from the roll sheet  1  or the paper core  17 . In the above third embodiment, the supply auxiliary mechanism  200  and the winding auxiliary mechanism  200  do not automatically perform the separation operation and the contact operation, but the user manually performs the separation operation and the contact operation. In the above fourth embodiment, in the operation sequence in printing, switching between separation and contact of the auxiliary mechanism  200  is performed automatically or manually according to at least one of a sheet type and a winding direction. In a fifth embodiment, when driving of a roll drive motor  34  in winding is stopped, switching between separation and contact of an auxiliary mechanism  200  with respect to a roll sheet  1  is performed. A description will be given below. 
     For example, in a winding apparatus for winding a roll sheet by driving the roll drive motor  34  like this case, unless the drive motor  34  is energized, a spool shaft  2  becomes freely rotated, causing loosening of the winding of the roll sheet and an abrasion. In order to avoid loosening of the winding of the roll sheet, after the apparatus body is turned ON, it is needed to have the roll drive motor  34  always energized even in print standby. However, having the roll drive motor  34  always energized increases a power consumption of the motor and the temperature of the motor rises. In general, therefore, the energization of the roll drive motor  34  is cut. Also when the apparatus body is turned OFF, the energization of the roll drive motor  34  is cut. This causes loosening of the winding. Therefore, in such a winding apparatus, after the apparatus body is turned ON, also in print standby or in the situation of turning OFF the apparatus body, it is needed to avoid loosening of the winding of the roll sheet. Then, in the fifth embodiment, before the energization of the roll drive motor  34  is cut, that is, before the roll drive motor  34  becomes undriven, loosening of the winding is prevented by automatically bringing a winding auxiliary mechanism  200  into contact with the roll sheet, so that degradation of a winding quality can be minimized. 
       FIG. 24  shows a flow of an operation sequence in printing, that is, in printing while winding (second usage form) according to the fifth embodiment. In the following description, signs in parentheses indicate numbers of steps in the flow shown in the figure. 
     If print data is received from a PC or the like (R 12 ), both the conveying roller drive motor  35  and the roll drive motor  34  of the lower conveying unit  70  are driven in the forward rotation direction (R 13 ), and conveyance of the sheet  1  is started. The leading end  9  of the sheet  1  located on the standby position is fed to the position immediately below the print head  15  (R 14 ). Then, the print head  15  scans the sheet in the width direction and ejects ink to perform printing (R 16 ). If the sheet  1  reaches the paper core  17 , the leading end  9  of the sheet  1  is fixed to the paper core  17  (R 17 ). After printing is finished (R 53 ), the pressure drive motor  33  of the lower conveying unit  70  keeps the winding auxiliary mechanism  200  into contact with the wound sheet  1  (R 54 ). Then, driving of the roll drive motor  34  is stopped (undriven) (R 54 ), and the printer enters a standby state (R 55 ). 
     While the present invention has been described with reference to exemplary embodiments, it is to be understood that the invention is not limited to the disclosed exemplary embodiments. The scope of the following claims is to be accorded the broadest interpretation so as to encompass all such modifications and equivalent structures and functions. 
     This application claims the benefit of Japanese Patent Applications No. 2014-234757, filed Nov. 19, 2014, and No. 2015-171424, filed Aug. 31, 2015, which are hereby incorporated by reference herein in their entirety.