Patent Publication Number: US-11020989-B2

Title: Roll paper steering devive, printing apparatus and method for assembling printing roll paper steering device

Description:
The present application is based on, and claims priority from JP Application Serial Number 2019-033650, filed Feb. 27, 2019, the disclosure of which is hereby incorporated by reference herein in its entirety. 
     BACKGROUND 
     1. Technical Field 
     The present disclosure relates to a roll paper steering device, a printing apparatus including the roll paper steering device, and a method for assembling the roll paper steering device in which the roll paper steering device is mounted to a main body frame. 
     2. Related Art 
     JP-A-2015-54782 is a known document disclosing a roll paper steering device and a printing apparatus including the same. JP-A-2015-54782 describes a technique for correcting meandering of a conveyed recording medium by moving, namely, steering a roll paper holding unit in an axial direction according to a position of an end portion of the recording medium. 
     The roll paper holding unit described above includes a roll shaft, which is a component that directly supports the roll paper. The roll shaft has a base portion rotably and axially supported by a bearing portion and a tip portion that protrudes toward the roll paper. When the roll paper holding unit holds the roll paper, the roll paper is heavier closer to the tip of the roll shaft than the bearing portion of the roll shaft. As a result, the roll shaft may deform downward with the bearing portion as a reference point due to the weight of the roll paper, and this may impair horizontal accuracy of the roll shaft. 
     In view of the roll shaft deforming due to the weight of the roll paper, the roll paper holding unit may be slightly inclined and mounted to a target member to offset the deformation of the roll shaft. A drive mechanism that steers such a roll paper holding unit includes an external thread such as a ball screw that rotates by a motor, where the shaft direction of the external thread is arranged parallel with a linear guide rail. 
     However, when the roll paper holding unit is slightly inclined and mounted to the target member as described above, the shaft direction of the external screw deviates from the direction of the linear guide rail and the external screw and the linear guide rail are no longer parallel with each other. As a result, a problem occurs in which meandering is corrected less accurately. 
     JP-A-2015-54782 does not describe or suggest a problem caused by the above-mentioned deviation. 
     SUMMARY 
     The present disclosure for solving the above-described problem includes a linear guide rail fixed to a main body frame, a holding shaft fixing member that is guided by and movably supported by the linear guide rail, can swing in a vertical direction and along the linear guide rail and is mounted with a roll paper holding unit having a roll shaft, a movable member that holds a motor and an external thread portion that rotates by the motor and that is adjustably mounted to the holding shaft fixing portion, a nut member fixed to the main body frame in a posture so that an axis of the external thread portion is parallel with the linear guide rail, a first adjustment unit that causes the holding shaft fixing member to swing to an inclination where a tip of the roll shaft is positioned upward to adjust the posture of the holding shaft fixing member with respect to the main body frame, and a second adjustment unit configured to adjust the position at which the movable member is mounted to the holding shaft fixing member. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a side cross-sectional view schematically illustrating an overview of the overall configuration of a printing apparatus according to an embodiment of the present disclosure. 
         FIG. 2  is a perspective view illustrating a roll paper steering device according to an embodiment of the present disclosure. 
         FIG. 3  is an enlarged perspective view illustrating a first main portion including a first adjustment unit and a swing fulcrum of the roll paper steering device according to an embodiment of the present disclosure. 
         FIG. 4  is a further enlarged perspective view illustrating the first adjustment unit of the roll paper steering device according to an embodiment of the present disclosure. 
         FIG. 5  is a front view illustrating the roll paper steering device according to an embodiment of the present disclosure in a posture where a linear guide rail and an external thread portion are parallel with each other. 
         FIG. 6  is an enlarged perspective view illustrating a second main portion including a second adjustment unit of the roll paper steering device according to an embodiment of the present disclosure. 
         FIG. 7  is an enlarged cross-sectional view taken along A-A in  FIG. 6  illustrating the second main portion including the second adjustment unit of the roll paper steering device according to an embodiment of the present disclosure. 
         FIG. 8  is a perspective view illustrating only main components of the roll paper steering device according to an embodiment of the present disclosure. 
     
    
    
     DESCRIPTION OF EXEMPLARY EMBODIMENTS 
     First, the present disclosure will be schematically described. 
     A roll paper steering device according to a first aspect of the present disclosure for solving the above-described problem includes a guide rail fixed to a main body frame, a guide engaged with the guide rail so as to be movable along the guide rail, a holding shaft fixing member supported by the guide rail via the guide, a roll paper holding unit including a roll shaft and mounted to the holding shaft fixing member, a movable member that holds a motor and an external thread portion that rotates by the motor and is adjustably mounted to the holding shaft fixing member, a nut member including an internal thread portion that receives the external thread portion, the nut member being fixed to the main body frame in a posture so that an axis of the external thread portion is parallel with the guide rail, a first adjustment unit that causes the holding shaft fixing member to swing to an inclination where a tip of the roll shaft is positioned upward, to thereby adjust the posture of the holding shaft fixing member with respect to the main body frame, and a second adjustment unit that adjusts the position at which the movable member is mounted to the holding shaft fixing member. 
     Herein, “roll paper” that is used in a “roll paper holding unit” or similar component is described using the term “roll paper”, which is commonly used to refer to elongated material in sheet form wound into a roll shape. The material used as “roll paper” may be paper, or a cloth material such as a “resin film” or a “fabric”. 
     According to this aspect, the position at which the movable member is mounted to the holding shaft fixing unit can be adjusted. Thus, even if the roll paper holding unit is slightly inclined and mounted to the mounting member and the external thread and the guide rail that make up the drive mechanism for steering are no longer parallel with each other, this deviation can be easily corrected. 
     A roll paper steering device according to a second aspect of the present disclosure is the roll paper steering device according to the first aspect, in which the second adjustment unit includes an abutted portion formed in the movable member, and an adjusting external thread that is inserted into a hole formed in the holding shaft fixing member and abuts against the abutted portion to adjust the position at which the movable member is mounted to the holding shaft fixing member. 
     According to this aspect, the second adjustment unit can be realized with a simple structure because the second adjustment unit consists of the abutted portion and the adjusting external thread. 
     A roll paper steering device according to a third aspect of the present disclosure is the roll paper steering device according to the first aspect or the second aspect, in which the first adjustment unit includes a swing fulcrum provided in the holding shaft fixing member, and causes the holding shaft fixing member to swing about the swing fulcrum to adjust the posture of the holding shaft fixing member with respect to the main body frame. 
     According to this aspect, the first adjustment unit can be realized with a simple structure. 
     A printing apparatus according to a fourth aspect of the present disclosure includes a feeding portion that feeds out roll paper set on a roll shaft toward a transport unit, and an ejecting unit that ejects liquid onto roll paper transported by the transport unit to form an image, in which the feeding portion includes the roll paper steering device of any one of the first to third aspects. 
     According to this aspect, the effect of any one of the first to third aspects can be obtained with a printing apparatus including a roll paper steering device. 
     A method for assembling a roll paper steering device according to a fifth aspect of the present disclosure is a method for assembling a roll paper steering device in which the roll paper steering device of any one of the first to third aspects is assembled to a main body frame in a state where mounting position and mounting angle of the roll paper steering device has been adjusted, the method including first adjustment assembly of fixing the guide to the holding shaft fixing member in a state where a mounting angle of the roll shaft has been adjusted using the first adjustment unit, and second adjustment assembly of fixing the movable member to the holding shaft fixing member in a state where an axis of the external thread portion for performing steering has been made parallel with an axis of the guide rail using the second adjustment unit, in which, after the guide is fixed to the holding shaft fixing member at a predetermined mounting angle in a posture where the holding shaft fixing member is guided to the guide rail via the guide in the first adjustment assembly, in the second adjustment assembly, the holding shaft fixing member is adjusted to a posture where the external thread portion is parallel with the guide rail and the movable member is fixed to the holding shaft fixing member at a predetermined mounting angle. 
     According to this aspect, the mounting angle of the roll shaft and the mounting position of the movable member for making the axis of the linear guide parallel with the axis of the external thread portion can be easily adjusted. As a result, the roll paper steering device can be easily assembled with high precision. 
     Now, the configuration of a roll paper steering device according to an embodiment of the present disclosure, the configuration of a printing apparatus according to an embodiment of the present disclosure, and a method for assembling the roll paper steering device will be described in detail with reference to the drawings. 
     Note that, in the following description, an outline of the overall configuration of the printing apparatus according to the present embodiment will be described first with reference to  FIG. 1 . Then, the configuration of the roll paper steering device, which is a main component of the present embodiment, will be described in detail with reference to  FIGS. 2 to 8 . 
     Next, the method for assembling the roll paper steering device, which is a main part of the present embodiment, will be described in detail based on  FIG. 2  to  FIG. 8  in order of steps of assembly. 
     Finally, operation and effects of the roll paper steering device and the method for assembling the printing apparatus and the roll paper steering device according to the present embodiment configured as described will be mentioned, followed by a brief description of other embodiments. 
     Embodiments 
     1. Outline of Entire Configuration of Printing Apparatus (see  FIG. 1 ) 
     A printing apparatus  1  according to the present embodiment includes a feeding portion  31  configured to feed roll paper R set on a roll shaft  32  toward a transport unit  41 , and an ejecting unit  11  configured to eject liquid onto the roll paper R transported by the transport unit  41  to form an image. 
     The feeding portion  31  is provided with a roll paper steering device  15 , which will be described later. 
     The printing apparatus  1  illustrated in the drawings includes a rotary drum  9  having a cylindrical body  3 , a rotary shaft  5 , and a plurality of arm portions  7  that connect the rotary shaft  5  to an inner surface  3   a  of the cylindrical body  3 . The arm portions  7  are spaced apart from each other in a circumferential direction C by a space S. 
     The feeding portion  31  is provided upstream in a transport direction A of the roll paper R. The feeding portion  31  supports the roll paper R due to the sheet-shaped roll paper R fed from the roll-shaped roll paper R mounted to the roll shaft  32  of the feeding portion  31  being wound around an outer surface  3   b  of the cylindrical body  3  of the rotary drum  9  at a predetermined winding angle. 
     UV ink in different colors as an example of liquid is ejected from the ejecting head  11  as an example of an ejecting unit onto the roll paper R that is wound around and supported by the outer surface  3   b  of the cylindrical body  3  of the rotary drum  9 . Then, the roll paper R is irradiated with UV light from a UV irradiator  13  as an example of a curing unit to cure the UV ink ejected onto the surface of the roll paper R. 
     After the UV ink is ejected onto the surface of the roll paper R and the roll paper R is cured, the roll paper R reaches a winding unit  33  downstream in the transport direction A and is sequentially wound by a roll shaft  34  of the winding unit  33 . Hereinafter, the roll paper R is continuously transported in a roll-to-roll transport manner while a desired image is printed on the roll paper R using the UV ink ejected from the ejecting head  11 . 
     As an example, guide rollers  37 ,  38  and winding rollers  39 ,  40  configured of driven rollers, and transport rollers  41  and discharge rollers  43  as transport units made up of a pair of nip rollers including a driving roller and a driven roller are disposed partway down a transport path  35  of the roll paper R. 
     The roll paper steering device  15  according to the present embodiment acts as a supporting member for the roll shaft  32  in the feeding portion  31  and is configured to accurately correct meandering of the roll paper R fed from the feeding portion  31  by reciprocating within a predetermined stroke range with a roll paper width direction B as the steering direction with respect to a main body frame  2  of the printing apparatus  1 . 
     2. Detailed Configuration of Roll Paper Steering Device (see  FIGS. 2 to 8 ) 
     Next, the configuration of the roll paper steering device  15  according to the present embodiment applied to the feeding portion  31  of the printing apparatus  1  will be described in detail. 
     The roll paper steering device  15  includes a linear guide rail  17  fixed to the main body frame  2  (see  FIG. 7 ), linear guides  19 A,  19 B engaged with the linear guide rail  17  so as to move in the steering direction along the linear guide rail  17 , a holding shaft fixing member  23  supported by the linear guide rail  17  via the linear guides  19 A,  19 B, a roll paper holding unit  21  including the roll shaft  32  and mounted to the holding shaft fixing member  23 , a movable member  27  holding a motor M 1  and an external thread portion  25  that rotates by the motor M 1  and being adjustably mounted to the holding shaft fixing member  23 , and an internal thread portion  29  that receives the external thread portion  25 . The roll paper steering device  15  also includes a nut member  30  fixed to the main body frame  2  with a bracket  61  in a posture so that an axis L 1  of the external thread portion  25  is parallel with the linear guide rail  17 , a first adjustment unit  45  that causes the holding shaft fixing member  23  to swing to an inclination where a tip  32   a  of the roll shaft  32  is positioned upward to adjust the posture of the holding shaft fixing member  23  with respect to the main body frame  2 , and a second adjustment unit  47  that adjusts the position at which the movable member  27  is mounted to the holding shaft fixing member  23 . 
     The linear guide rail  17  is a square bar-shaped member having an upper surface and a lower surface formed with grooves  18 . The linear guide rail  17  is fixed to the main body frame  2  along the width direction B, which is the steering direction. 
     As an example, the two linear guides  19 A,  19 B are mounted to the linear guide rail  17  in a state where claw portions  20  that protrude so as to face inward are engaged with the grooves  18  in the linear guide rail  17 . 
     The two linear guides  19 A,  19 B are screwed into the front surface of a holding shaft fixing plate  23  serving as the holding shaft fixing member after the angle at which the two linear guides  19 A,  19 B are mounted is adjusted using the first adjustment unit  45  described below. 
     As illustrated in  FIG. 2 , the holding shaft fixing plate  23  is a thick, substantially rectangular tabular member formed with two window portions  49 A,  49 B and is disposed in a vertical posture along a vertical direction Z. As illustrated in  FIGS. 2, 3 and 5 , the two linear guides  19 A,  19 B are mounted to left and right sides of the holding shaft fixing plate  23  near the upper end of the holding shaft fixing plate  23 . 
     Further, the roll shaft  32  is horizontally supported on the rear face of the holding shaft fixing plate  23  through two bearing portions  51 A,  51 B. Note that a motor M 2  that imparts driving force for feeding the roll paper R is provided directly on a base end portion of the roll shaft  32  and that the roll paper holding portion  21  is comprised of the roll shaft  32 , the two bearing portions  51 A,  51 B and the motor M 2 . 
     Among the two window portions  49 A,  49 B formed in the holding shaft fixing plate  23 , the window portion  49 B has a larger aperture and is provided to avoid interference with the motor M 2  of the roll paper holding unit  21 . 
     The motor M 1  that imparts driving force for performing a steering operation is disposed on a front face of the square window portion  49 A, which has the smaller aperture of the two window portions  49 A,  49 B formed in the holding shaft fixing plate  23 . Note that the motor M 1  is mounted in a horizontal posture using a mounting bracket  53  formed by folding an end portion of the movable plate  27  forward. The movable plate  27  is to be described next. 
     The movable plate  27  serves as a movable member and is a thin, substantially rectangular tabular member that is long in the width direction B. A block-shaped bearing portion  55  is mounted to the front face of the movable plate  27  near the mounting bracket  53 , and the base end portion of a ball screw  25 , which is an example of an external thread portion, is supported by the bearing portion  55  in a cantilever state. 
     A coupling  59  is coupled to the base end portion of the ball screw  25 . Power is transmitted from an output shaft  57  (see  FIG. 5 ) of the motor M 1 , which is also coupled to the coupling  59 , such that the ball screw  25  is configured to rotate in forward and reverse directions. 
     The internal thread portion  29  of the nut member  30  fixed to the main body frame  2  with the bracket  61  therebetween is screwed into the ball screw  25 . When the ball screw  25  rotates, the ball screw  25  becomes integral with the motor M 1  and the movable plate  27  while rotating and moves back and forth in the width direction B. Note that the nut member  30  remains in place without rotating because the nut member  30  is fixed to the main body frame  2 . 
     The movable plate  27  is formed with two separation regulating portions  63 A,  63 B that are spaced apart in the width direction B so as to maintain a parallel interval T (see  FIG. 5 ) from the linear guide rail  17 . In the present embodiment, the separation regulating portions  63 A,  63 B are the bottom surfaces of two recessed portions  65 A,  65 B having a predetermined depth and formed downward from the upper end edge of the movable plate  27 . 
     The position at which the movable plate  27  is mounted to the holding shaft fixing plate  23  is provided with play so as to be adjustable by a predetermined amount in the vertical direction Z and the width direction B. After the mounting position of the movable plate  27  is adjusted within this range of play, the movable plate  27  is fixed to the holding shaft fixing plate  23  using a lockscrew  67 . 
     The positions at which the linear guides  19 A,  19 B are mounted to the holding shaft fixing plate  23  are also provided with play so as to be adjustable by a predetermined amount in the vertical direction Z and the width direction B. Then, the first adjustment unit  45  to be described next is adjusted. Through this adjustment, the relative positions of the left and right linear guides  19 A,  19 B change and the holding shaft fixing plate  23  swings about a swing fulcrum O so that the mounting angle of the roll shaft  32  can be set to an upward angle where the tip  32   a  faces upward by a predetermined amount. 
     The first adjustment unit  45  is made up of, for example, the swing fulcrum O provided on an upper portion of the holding shaft fixing plate  23  near the left end of the holding shaft fixing plate  23  and, for example, an adjustment operation unit  68  provided on an upper portion of the holding shaft fixing plate  23  near the right end of the holding shaft fixing plate  23 . 
     When the adjustment operation unit  68  is operated, the holding shaft fixing plate  23  swings about the swing fulcrum O and the holding shaft fixing plate  23  can be adjusted to an inclination where the tip  32   a  of the roll shaft  32  fixed to the holding shaft fixing plate  23  is positioned upward. 
     The adjustment operation unit  68  is made up of, for example, an adjustment base plate  69  having an L-shaped cross section and including a back side plate  69   a  fixed to the back side of the holding shaft fixing plate  23  and an upper surface plate  69   b  bent forward into a peak, a nut portion  71  provided on a lower surface of the upper surface plate  69   b , and an adjustment screw  73  that screws into the nut portion  71 . 
     A lower end surface of the adjustment screw  73  abuts against the upper surface of the linear guide  19 B on the right of the lower end surface. Rotating the adjustment screw  73  in the forward or reverse direction while the adjustment screw  73  abuts against the upper surface changes the protruding length of the protruding portion of the adjustment screw  73 , which protrudes below the nut portion  71 . Based on the length of the protruding portion, the holding shaft fixing plate  23  can be swung by a predetermined angle around the swing fulcrum O to adjust the mounting angle of the roll shaft  32  to a desired angle. 
     The second adjustment unit  47  is made up of an abutted portion  75  formed on the movable plate  27  and used for position adjustment, and an adjusting external thread  79  that is inserted into a hole  77  (see  FIG. 6 ) formed in the holding shaft fixing plate  23  and adjusts the position at which the movable plate  27  is mounted to the holding shaft fixing plate  23  by abutting against the abutted portion  75 . 
     The abutted portion  75  is made up of two inclined contact plates  75 A,  75 B provided so as to protrude from left and right lower end portions of the movable plate  27  toward obliquely forward lower portions of the movable plate  27 . Two adjusting external threads  79  are provided. These threads  79  are screwed into internal thread portions formed on the inner wall of the hole  77 . The two adjusting external threads  79  are made to protrude toward the front surface of the holding shaft fixing plate  23  such that tips  79   a  of the adjusting external threads  79  abut against inclined back surfaces  75   a  of the contact plates  75 A,  75 B. As a result, the two contact plates  75 A,  75 B can be individually pressed upward by a predetermined stroke, to thereby adjust the position at which the movable plate  27  is mounted to the holding shaft fixing plate  23 . 
     3. Method for Assembling Roll Paper Steering Device (see  FIGS. 2 to 8 ) 
     Next, a method for assembling the roll paper steering device in which the mounting position and mounting angle of the roll paper steering device  15  according to the present embodiment configured as described above are adjusted and the roll paper steering device  15  is assembled to the main body frame  2  of the printing apparatus  1  according to the present embodiment will be described in detail in order of the steps of assembly. 
     The method for assembling a roll paper steering device according the present embodiment includes a first adjustment assembly step P 1  for adjusting the mounting angle of the roll shaft  32 , and a second adjustment attaching step P 2  for adjusting the mounting position of the movable plate  27 . The first adjustment assembly step P 1  is a step in which the linear guides  19 A,  19 B are fixed to the holding shaft fixing plate  23  at a predetermined mounting angle in a posture where the holding shaft fixing plate  23  is guided to the linear guide rail  17  via the linear guides  19 A,  19 B. After performing the first adjustment assembly step P 1 , in the second adjustment assembly step P 2 , the ball screw  25  is adjusted to a posture parallel with the linear guide rail  17  and the movable plate  27  is fixed to the holding shaft fixing plate  23  at a predetermined mounting position. 
     A. First Adjustment Assembly Step (see  FIGS. 2 to 5 ) 
     The first adjustment assembly step P 1  is a step for fixing the linear guides  19 A,  19 B to the holding shaft fixing plate  23  in a state where the mounting angle of the roll shaft  32  has been adjusted using the first adjustment unit  45 . More specifically, lockscrews  81  (see  FIG. 8 ) that fix the linear guides  19 A,  19 B to the holding shaft fixing plate  23  (see  FIG. 8 ) are loosened in advance to create a state where the mounting positions of the linear guides  19 A,  19 B can be freely adjusted. When the adjustment screw  73  is rotated in the reverse direction in this state, the lower end surface of the adjustment screw  73  at the portion protruding below the nut portion  71  moves in a direction separating from the upper surface of the linear guide  19 B on the right of the lower end surface. Here, the heavy motor M 2  is fixed to the right side of the holding shaft fixing plate  23  below the linear guide  19 B and, in a state where the holding shaft fixing plate  23  is not fixed to the linear guides  19 A,  19 B, the lower end surface of the adjustment screw  73  moves toward a direction separating from the upper surface of the linear guide  19 B due to force that causes the holding shaft fixing plate  23  to rotate clockwise in  FIG. 5  about the swing fulcrum. When this happens, the holding shaft fixing plate  23  follows the movement of the adjustment screw  73  and rotates clockwise by the distance moved by the adjustment screw  73 . 
     As a result, the roll shaft  32  fixed to the holding shaft fixing plate  23  via the bearing portions  51 A,  51 B transitions to an inclined posture in which the tip  32   a  is positioned slightly upward. Then, after the mounting angle of the roll shaft  32  has been changed to a predetermined angle by adjusting the tightness of the adjustment screw  73 , the lockscrews  81  are tightened to fix the linear guides  19 A,  19 B to the holding shaft fixing plate  23 . 
     B. Second Adjustment Assembly Step (See  FIGS. 6 to 8 ) 
     The second adjustment assembly step P 2  is a step in which the movable plate  27  is fixed to the holding shaft fixing plate  23  in a state where the axis L 1  of the ball screw  25  for performing steering is made parallel with an axis L 2  of the linear guide rail  17  using the second adjustment unit  47 . 
     More specifically, the lockscrew  67  used to fix the movable plate  27  to the holding shaft fixing plate  23  is loosened in advance to create a state where the mounting position of the movable plate  27  can be freely adjusted. Then, for example, upper end portions of thick, rectangular tabular-shaped adjustment jigs  83 A,  83 B are fitted into the lower surface of the linear guide rail  17  that faces the two recesses  65 A,  65 B formed in the upper portion of the movable plate  27 . A pair of top and bottom positioning pins  85  is provided on the front face of each of the adjustment jigs  83 A,  83 B. These positioning pins  85  are inserted into positioning holes  87  (see  FIG. 7 ) formed in the main body frame  2  to position the adjustment jigs  83 . 
     After completing this preparation operation, the tips  79   a  of the adjusting external threads  79  are made to abut against the inclined rear face  75   a  of the contact plate  75  integral with the movable plate  27 . 
     When the adjusting external threads  79  are further tightened, an upward force is applied to the contact plate  75 , allowing the movable plate  27  integral with the contact plate  75  to move upward by a predetermined distance. 
     When the separation regulating portions  63 A,  63 B as the bottom surfaces of the two recesses  65 A,  65 B in the movable plate  27  abut against lower end portions of the two adjustment jigs  83 A,  83 B, the movable plate  27  is restricted from moving further upward. In this state, the lockscrew  67  is tightened to fix the movable plate  27  to the holding shaft fixing plate  23 . 
     After fixing the movable plate  27 , the series of operations for assembling the roll paper steering device  15  is complete when the adjustment jigs  83 A,  83 B are removed by pulling out the adjustment jigs  83 A,  83 B behind the rear face of the holding shaft fixing plate  23 . Note that  FIGS. 1 to 5  do not illustrate the structural portion in which the adjustment jigs  83 A,  83 B are removed by being pulled out behind the rear face of the holding shaft fixing plate  23 . 
     With the roll paper steering device  15  according to the present embodiment configured as described above, because the tip  32   a  of the roll shaft  32  can be biased slightly upward, the horizontal state of the roll shaft  32  can be maintained even when heavy roll paper R is attached to and set on the roll shaft  32 . In addition, the axis L 1  of the ball screw  25  and the axis L 2  of the linear guide rail  17  can be kept parallel with each other, resulting in smoother steering performed when the ball screw  25  rotates and therefore a highly-accurate steering operation. 
     With the printing apparatus  1  according to the present embodiment configured as described above, the roll paper R can be transported in a state where meandering of the roll paper R fed out from the feeding portion  31  has been corrected with high accuracy due to the smooth and highly precise steering operation performed by the roll paper steering device  15 . As a result, the quality of the image printed on the roll paper R can be improved. In addition, transportation problems such as blockage of the roll paper R caused by meandering of the roll paper R can be reduced. 
     With the method for assembling a roll paper steering device according to the present embodiment configured as described above, the mounting angle of the roll shaft  32  and the mounting position of the movable plate  27  for making the axis L 2  of the linear guide  17  parallel with the axis L 1  of the ball screw  25  can be easily adjusted. As a result, the roll paper steering device  15  can be easily assembled with high precision. 
     Other Exemplary Embodiments 
     The roll paper steering device  15  and the method for assembling the printing apparatus  1  and the roll paper steering device  15  according to the present disclosure have the configurations and components as described above, but it goes without saying that parts of these configurations may be changed or omitted without departing from the gist of the disclosure of the present application. 
     For example, the roll paper steering device  15  according to the present disclosure can be applied to the winding unit  33  in addition to the feeding portion  31  of the printing apparatus  1 . Furthermore, the roll paper steering device  15  according to the present disclosure is not limited to the printing apparatus  1 , and can be applied to other portions or devices that perform a shaft adjustment operation. 
     The external thread portion  25  in the roll paper holding unit  21  is not limited to the ball screw  25  and may be a screw with another structure, such as a trapezoidal screw. In addition, the holding shaft fixing member  23  and the movable member  27  do not necessarily need to be plate-like members and may have another structure, such as a block-shaped structure or a frame structure. 
     While one adjustment screw  73  used in the first adjustment unit  45  is provided for one linear guide  19 , a plurality of, for example, two adjustment screws  73  may be provided. In a configuration where two adjustment screws  73  are provided at positions spaced apart from each other, the adjustment screws  73  correct the inclination of the linear guide  19  when the linear guide  19  is inclined. As a result, the surface at which the linear guide  19  abuts against the linear guide rail  17  becomes parallel with the linear guide rail  17  and the linear guide rail  17  can be held more reliably. 
     In addition, there is a condition that movement of the movable plate  27  in the steering direction not be hindered, but the movable plate  27  itself may be provided with a protruding portion or similar component that abuts against part of the linear guide rail  17  to fix the movable plate  27  to the holding shaft fixed plate  23  at a position where the tip of the protruding portion is in contact with the linear guide rail  17 . When adopting such a configuration, the adjustment jig  83  need not be used in the second adjustment assembly step P 2 .