Patent Publication Number: US-2021187946-A1

Title: Medium feeding device and recording apparatus

Description:
The present application is based on, and claims priority from JP Application Serial Number 2019-231080, filed Dec. 23, 2019, the disclosure of which is hereby incorporated by reference herein in its entirety. 
     BACKGROUND 
     1. Technical Field 
     The present disclosure relates to a medium feeding device configured to feed a medium and a recording apparatus including the medium feeding device. 
     2. Related Art 
     A recording apparatus such as a facsimile or a printer is, in some cases, configured to manually feed recording paper, which is an example of a medium, into the apparatus. Moreover, as JP-A-5-162871 discloses, in some cases, such a recording apparatus of the related art configured to perform manual feeding includes a detection unit used to detect that recording paper is set in a manual feeding tray, and, when the detection unit detects that recording paper is set in the manual feeding tray, the recording apparatus shifts to a manual feeding mode. 
     When operating the recording apparatus having such an above-described mechanism, a user may take their hand off the recording paper in a state in which the leading end of the recording paper that has been set by the user reaches a detection position of the detection unit but does not reach a paper feeding roller. The recording apparatus of the related art determines that the recording paper is properly set even in such a case and starts a feeding operation in a state in which the recording paper does not reach the paper feeding roller. 
     The recording apparatus then determines such a condition as a feeding anomaly based on the fact that a detection unit provided further downstream than the paper feeding roller has not detected the leading end of the recording paper for a predetermined time. As a result, the recording apparatus cannot determine whether the cause of the feeding anomaly is a recording paper setting error or a jam after feeding starts and cannot issue an appropriate alert. Thus, user convenience may be decreased. 
     SUMMARY 
     According to an aspect of the present disclosure, a medium feeding device includes a feeding roller that is provided in a medium feeding path through which a medium is fed and that feeds a medium downstream by rotating in a forward direction in response to power of a motor, a nip roller that is provided in the medium feeding path and that nips a medium in cooperation with the feeding roller and rotates, and a controller configured to control the motor. Based on an increase in a variation value varying in accordance with a drive load of the motor, the controller controls the motor and causes the feeding roller to start a medium feeding operation. 
     According to an aspect of the present disclosure, a recording apparatus includes a recording head configured to perform recording on a medium, and the medium feeding device configured to feed a medium toward a region facing the recording head. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a perspective view of a printer according to the present disclosure as viewed from the front. 
         FIG. 2  illustrates an overall structure of medium feeding paths of the printer according to the present disclosure. 
         FIG. 3  is a perspective view of the printer according to the present disclosure as viewed from the rear. 
         FIG. 4  illustrates a portion of the medium feeding path of the printer according to the present disclosure. 
         FIG. 5  is a block diagram of a control system of the printer according to the present disclosure. 
         FIG. 6  illustrates a waveform example of a drive current value of a transport motor. 
         FIG. 7  is a flowchart of a first control example performed by a controller. 
         FIG. 8  is a flowchart of a second control example performed by the controller. 
     
    
    
     DESCRIPTION OF EXEMPLARY EMBODIMENTS 
     Hereinafter, the present disclosure will be schematically described. 
     A medium feeding device according to a first aspect includes a feeding roller that is provided in a medium feeding path through which a medium is fed and that feeds a medium downstream by rotating in a forward direction in response to power of a motor, a nip roller that is provided in the medium feeding path and that nips a medium in cooperation with the feeding roller and rotates, and a controller configured to control the motor. Based on an increase in a variation value varying in accordance with a drive load of the motor, the controller controls the motor and causes the feeding roller to start a medium feeding operation. 
     When the leading end of a medium enters between the feeding roller and the nip roller, the variation value varying in accordance with the drive load of the motor changes, and it is thereby possible to detect that the leading end of the medium enters between the feeding roller and the nip roller. The present aspect utilizes such a property. The controller controls the motor and causes the feeding roller to start the medium feeding operation based on an increase in the variation value varying in accordance with the drive load of the motor, and it is thereby possible to suppress a feeding operation from being started in a state in which a medium setting error occurs. As a result, when a feeding anomaly occurs after the feeding operation of a medium is started, it is possible to issue a user an appropriate alert. Thus, user convenience can be improved. 
     According to a second aspect, in the medium feeding device according to the first aspect, the controller emits a notification sound when an increase in the variation value exceeds a threshold value. 
     According to the present aspect, when the variation value exceeds the threshold value, the controller emits the notification sound, and it is thereby possible for a user to know that a medium is nipped by the feeding roller and the nip roller, due to the notification sound. Thus, user convenience is improved. 
     According to a third aspect, the medium feeding device according to the first or second aspect further includes, a medium detection portion that is provided upstream of the feeding roller in the medium feeding path and that detects passage of a medium. When the medium detection portion detects passage of a leading end of a medium, the controller controls the motor to rotate the feeding roller in a reverse direction that is opposite to the forward direction, and, when detecting an increase in the variation value with the feeding roller being rotated in the reverse direction, the controller changes a driving direction of the motor and starts the medium feeding operation. 
     According to the present aspect, when the medium detection portion detects passage of the leading end of a medium, the controller controls the motor to rotate the feeding roller in the reverse direction that is opposite to the forward direction, and a change in the drive current value when the leading end of the medium is entering between the feeding roller and the nip roller thereby becomes noticeable. Thus, it is possible to detect with greater certainty that the leading end of the medium reaches between the feeding roller and the nip roller. 
     According to a fourth aspect, in the medium feeding device according to the third aspect, a rotational speed of the feeding roller when the feeding roller is rotated in the reverse direction is lower than the rotational speed of the feeding roller when the feeding roller is rotated in the forward direction in the medium feeding operation. 
     According to the present aspect, the rotational speed of the feeding roller when the feeding roller is rotated in the reverse direction is lower than the rotational speed of the feeding roller when the feeding roller is rotated in the forward direction in the medium feeding operation, and it is thereby possible to suppress damage to the leading end of a medium when the leading end of the medium enters between the feeding roller and the nip roller from being caused. 
     According to a fifth aspect, the medium feeding device according to the first or second aspect further includes a medium detection portion that is provided upstream of the feeding roller in the medium feeding path and that detects passage of a medium. When not detecting an increase in the variation value, even if a predetermined time elapses from the medium detection portion detecting passage of a leading end of a medium, the controller emits an alert prompting insertion of the medium. 
     According to the present aspect, when not detecting an increase in the drive current value, even if a predetermined time elapses from the medium detection portion detecting passage of the leading end of the medium, the controller emits the alert prompting insertion of the medium. Thus, it is possible to encourage a user to take appropriate action, and, by extension, user convenience is improved. 
     According to a sixth aspect, a recording apparatus includes a recording head configured to perform recording on a medium, and the medium feeding device according to any one of the first to fifth aspects, the medium feeding device feeding a medium toward a region facing the recording head. 
     According to the present aspect, in the recording apparatus, it is possible to obtain the operational effect of the above-described any one of the first to fifth aspects. 
     According to a seventh aspect, the recording apparatus according to the sixth aspect further includes a medium supporting portion that is provided at a position facing the recording head, that supports a medium, and that is configured so that a gap between the medium supporting portion and the recording head is adjusted under control of the controller. When detecting an increase in the variation value, the controller widens the gap between the medium supporting portion and the recording head. 
     According to the present aspect, when detecting an increase in the variation value, the controller widens the gap between the medium supporting portion and the recording head. Thus, when a thick medium is fed, it is possible to avoid the medium rubbing against the recording head and avoid damage to the recording head. 
     According to an eighth aspect, the recording apparatus according to the sixth aspect further includes: a reverse path configured to cause a side of a medium to be reversed by using a portion of the medium feeding path being a linear path extending horizontally from upstream to downstream, that is, from a rear of an apparatus main body having the recording head toward a front of the apparatus main body; and a reverse unit that is configured to be attached to and detached from the apparatus main body having the recording head, that constitutes a portion of the reverse path by being attached to the apparatus main body, and that causes a portion of the reverse path to be exposed by being detached from the apparatus main body. The medium feeding path is caused to be used by detaching the reverse unit from the apparatus main body. 
     According to a ninth aspect, the recording apparatus according to the eighth aspect further includes: a medium supporting portion that is provided at a position facing the recording head, that supports a medium, and that is configured so that a gap between the medium supporting portion and the recording head is adjusted under control of the controller; and a unit detection portion configured to detect an attachment state of the reverse unit with respect to the apparatus main body. When the unit detection portion detects detachment of the reverse unit from the apparatus main body, the controller widens the gap between the medium supporting portion and the recording head. 
     According to the present aspect, when the unit detection portion detects detachment of the reverse unit from the apparatus main body, the controller widens the gap between the medium supporting portion and the recording head. Thus, when a thick medium is fed, it is possible to avoid the medium rubbing against the recording head. 
     According to a tenth aspect, in the recording apparatus according to the seventh or ninth aspect, before the recording head starts a recording operation, the controller adjusts the gap between the medium supporting portion and the recording head in accordance with the variation value. 
     The variation value varies more widely as the thickness of the medium increases, and it is thereby possible to grasp the thickness of the medium based on the variation value. Based on such a property, in the present aspect, before the recording head starts the recording operation, the controller adjusts the gap between the medium supporting portion and the recording head in accordance with the variation value. Thus, appropriate recording quality can be achieved. 
     Hereinafter, the present disclosure will be described in detail. 
     Hereinafter, an ink jet printer  1  will be described as an example of a recording apparatus. Hereinafter, the ink jet printer  1  will simply be referred to as a printer  1 . 
     Regarding the X-Y-Z coordinate system in each figure, the X-axis direction denotes a moving direction of a recording head  17  (refer to  FIG. 2 ) and denotes the width direction of a medium to be subjected to recording. The X-axis direction also denotes the apparatus width direction. In a state of facing the printer  1 , the +X direction is the leftward direction, and the −X direction is the rightward direction. 
     The Y-axis direction denotes the apparatus depth direction and a direction parallel to a medium feeding direction during recording. The +Y direction is a direction from the rear toward the front of the apparatus, and the −Y direction is a direction from the front toward the rear of the apparatus. In the present exemplary embodiment, out of side surfaces constituting the periphery of the printer  1 , a side surface having an operation panel  6  is the front surface of the apparatus. 
     The Z-axis direction denotes a direction parallel to the vertical direction and the apparatus height direction. The +Z direction is the vertically upward direction, and the −Z direction is the vertically downward direction. 
     Hereinafter, a direction in which a medium is fed is sometimes referred to as “downstream”, and a direction opposite thereto is sometimes referred to as “upstream”. 
     First, the overall configuration of the printer  1  will be outlined. In  FIG. 1 , the printer  1  includes a scanner unit  3  provided at an upper portion of an apparatus main body  2  configured to perform ink jet recording on a medium. That is, the printer  1  is configured as a multi-function apparatus having, in addition to an ink jet recording function, a document reading function. 
     The scanner unit  3  is rotatably provided on the apparatus main body  2  and rotates to be in a closed state illustrated in  FIG. 1  and in an open state, which is not illustrated. 
     The scanner unit  3  has a document cover  5  by which a document platen, which is not illustrated, is opened and closed. 
     In the front surface of the apparatus, the apparatus main body  2  has the operation panel  6  including components such as an operating portion used to set various operations and a display portion used to display, for example, contents of print settings and a preview of a print image. 
     A front surface cover  4  is provided in the front surface of the apparatus, and, by the front surface cover  4  being opened, components such as a medium cassette  10 , a medium discharge opening  9 , and a medium receiving tray  21 , which are illustrated in  FIG. 2  but not in  FIG. 1 , are exposed. 
     An upper surface cover  8  is provided on the rear side of the upper surface of the apparatus, and, by the upper surface cover  8  being opened, an inclined supporting portion  12 , which is illustrated in  FIG. 2  but not in  FIG. 1 , is exposed. 
     Next, medium feeding paths of the printer  1  will be described with reference to  FIGS. 2 to 4 . As  FIG. 2  illustrates, the printer  1  has four medium feeding paths that are a medium feeding path T 1  from the medium cassette  10  provided in a lower portion of the apparatus, a medium feeding path T 2  from the rear side of an upper portion of the apparatus, a medium feeding path T 3  (refer to  FIG. 4 ) from the rear of the apparatus, and a medium feeding path  14  through which a medium that has been subjected to recording is fed again toward a reverse roller  20 . Each medium feeding path is made of a path forming member, and the detailed description thereof will be omitted. 
     In the medium feeding path T 1 , a medium is fed from the medium cassette  10  by a pick roller  11  and reversed and fed toward a feeding roller pair  15  by the reverse roller  20 . Reference S in  FIG. 2  denotes media set in the medium cassette  10 . 
     In the medium feeding path T 2 , a medium supported by the inclined supporting portion  12  with the medium orientated in an inclined manner is fed toward the feeding roller pair  15  by a supply roller  13 . 
     The medium feeding path T 3  is a path for manually feeding a medium from the rear toward the front of the apparatus. Although described in detail below, in the present specification, the medium feeding path T 3  is set to be a path from an adapter  23  (refer to  FIG. 4 ), which will be described below, to the medium receiving tray  21 . The medium feeding path T 3  is a substantially linear path and is, in the present exemplary embodiment, a path extending in the horizontal direction. 
     Examples of a medium include a sheet material with flexibility, such as recording paper, and a plate-shaped body that hardly bends, such as an optical disc. Out of such examples, the plate-shaped body that hardly bends, such as an optical disc, is fed by using the medium feeding path T 3 . A medium that is small and not square, such as an optical disc, is fed into the medium feeding path T 3  in a state of being set in a tray for such a medium. 
     As  FIG. 5  illustrates, the feeding roller pair  15  configured to feed a medium to a position facing the recording head  17  is constituted by a feeding roller  15   a  and a nip roller  15   b . The feeding roller  15   a  is configured to rotate in one of the forward direction (counterclockwise direction in  FIGS. 2 and 5 ) in which the feeding roller  15   a  feeds a medium downstream in response to power from a transport motor  53 , which will be described below, and the reverse direction (clockwise direction in  FIGS. 2 and 5 ) in which the feeding roller  15   a  feeds a medium upstream. In the present exemplary embodiment, the feeding roller  15   a  includes a metal shaft body and a high friction layer provided on a surface of the metal shaft body. 
     The nip roller  15   b  is provided so as to be able to advance and retreat with respect to the feeding roller  15   a  and is pressed toward the feeding roller  15   a  by a spring, which is not illustrated, and, while nipping a medium in cooperation with the feeding roller  15   a , the nip roller  15   b  is driven to rotate. Although an illustration is omitted, the nip roller  15   b  is constituted by a plurality of nip rollers provided in the axial direction of the feeding roller  15   a  at an appropriate interval. The nip roller  15   b  is made of a low friction material and, in the present exemplary embodiment, the nip roller  15   b  is made of Polyoxymethylene (POM). 
     The feeding roller  15   a  and the nip roller  15   b  constitute a medium feeding device  14 . 
     Referring back to  FIG. 2 , the recording head  17  and a medium supporting portion  18  are disposed so as to face each other downstream of the feeding roller pair  15 . The medium supporting portion  18  defines a gap between the recording head  17  and a medium by supporting the medium. 
     A carriage  16  having the recording head  17  is provided so as to be able to reciprocate in the medium width direction and moves in the X-axis direction in response to power from a carriage motor  51  (refer to  FIG. 5 ) controlled by a controller  50  (refer to  FIG. 5 ). 
     The carriage  16  is configured to be displaced in the Z-axis direction due to an adjustment mechanism  49  (refer to  FIG. 5 ) controlled by the controller  50  (refer to  FIG. 5 ), and the adjustment mechanism  49  is configured to adjust a gap between the recording head  17  and the medium supporting portion  18 . The adjustment mechanism  49  can be constituted by, for example, a motor and a cam mechanism, which are not illustrated. 
     A discharge roller pair  19  is provided downstream of the recording head  17  and the medium supporting portion  18 , and a medium that has been subjected to recording is discharged toward the outside of the apparatus by the discharge roller pair  19  and supported by the medium receiving tray  21 . 
     When recording is performed on the both sides of a medium, after the recording head  17  performs recording on a first side of the medium, the medium is back-fed in the −Y direction to be fed into the medium feeding path  14  and reversed by the reverse roller  20 . Thus, recording can be performed on a second side of the medium. 
     Next, the medium feeding path T 3  will be described with reference to  FIGS. 3 and 4 . A reverse unit  24  is provided at the rear of the apparatus main body  2  so as to be attachable to and detachable from the apparatus main body  2 . The reverse unit  24  includes the reverse roller  20 . By the reverse unit  24  being detached from the apparatus main body  2  as illustrated by the change from the upper image in  FIG. 3  to the lower image in  FIG. 3 , an opening  2   a  is formed at the rear of the apparatus main body  2  as the lower image of  FIG. 3  illustrates. Due to the opening  2   a , when a jam occurs in the apparatus main body  2 , a medium that has been jammed can be removed. 
     In addition, by the reverse unit  24  being detached from the apparatus main body  2 , the medium feeding path T 3  is exposed as the upper image of  FIG. 4  illustrates, and the medium feeding path T 3  becomes available. 
     As  FIG. 2  illustrates, the adapter  23  is provided at an upper portion of the reverse unit  24 . The adapter  23  is attachable to and detachable from the reverse unit  24 . By the reverse unit  24  being detached from the apparatus main body  2 , the adapter  23  can be attached to and detached from the reverse unit  24 . The adapter  23  that has been detached from the reverse unit  24  can be attached to a region of the apparatus main body  2  to which the reverse unit  24  was attached as the lower image of  FIG. 4  illustrates. A medium S to be fed through the medium feeding path T 3  is supported by the attached adapter  23 . 
     Next, a control system in the printer  1  will be described with reference to  FIG. 5 . 
     The controller  50  performs various controls of the printer  1 , such as feeding, transporting, discharging and recording of a medium. The controller  50  is also a constituent of the medium feeding device  14 . Signals from the operation panel  6  are input into the controller  50 , and signals for display of the operation panel  6  and, in particular, for realization of a user interface (UI) are transmitted from the controller  50  to the operation panel  6 . 
     The controller  50  controls motors relevant to a medium feeding operation and a recording operation, that is, the carriage motor  51 , a supply motor  52 , and the transport motor  53 . In the present exemplary embodiment, each motor is a DC motor. The transport motor  53  constitutes the medium feeding device  14 . 
     Detection signals from detection portions that are a position detection portion  57 , a rotation detection portion  58 , a first medium detection portion  59 , a second medium detection portion  60 , and a unit detection portion  61  are also input into the controller  50 . 
     The position detection portion  57  is a linear encoder and is a detection portion configured to detect the position of the carriage  16  in the X-axis direction. The rotation detection portion  58  is a rotary encoder and is a detection portion configured to detect the amount of rotation and the rotational speed of the feeding roller  15   a.    
     The unit detection portion  61  is a detection portion configured to detect whether the reverse unit  24  (refer to  FIG. 3 ) is attached. The unit detection portion  61  can be constituted by a contact sensor or a noncontact sensor. 
     The first medium detection portion  59  is provided near and upstream of the feeding roller pair  15  and is a detection portion configured to detect passage of the leading end and the trailing end of a medium. In the carriage  16 , the second medium detection portion  60  is provided at a position facing a medium and is used to detect the position of an end portion of a medium in the width direction thereof and, in some cases, to detect passage of the leading end and the trailing end of a medium. The second medium detection portion  60  can be constituted by a noncontact sensor, and the first medium detection portion  59  can be constituted by a contact sensor or a noncontact sensor. 
     In the present exemplary embodiment, the first medium detection portion  59 , the second medium detection portion  60 , and the unit detection portion  61  constitute the medium feeding device  14 . 
     The controller  50  includes a CPU  54 , a flash ROM  55 , and a RAM  56 . The CPU  54  performs various kinds of arithmetic processing in accordance with the program stored in the flash ROM  55  and controls operations of the entire printer  1 . The flash ROM  55 , which is an example of a memory unit, is a nonvolatile memory enabling reading and writing. Various kinds of setting information that have been input by a user by using the operation panel  6  are also recorded into the flash ROM  55 . Various kinds of information are temporarily stored in the RAM  56 , which is an example of a memory unit. 
     The controller  50  also includes an interface  62  and can communicate, via the interface  62 , with an external computer  90 . 
     Next, the control performed by the controller  50  when a medium is manually fed into the medium feeding path T 3  will be described with reference to  FIGS. 5 and 6  and subsequent figures. Hereinafter, a medium is referred to as a medium S, and the leading end of the medium S is referred to as a leading end Sf. 
     The controller  50  is configured to detect that the leading end Sf of the medium S enters the feeding roller pair  15 , by referring a variation value varying in accordance with a drive load of the transport motor  53  and a threshold value with respect to the variation value. As the variation value, for example, a drive current value of the transport motor  53  can be used. 
       FIG. 6  illustrates an example of a waveform L of the drive current value of the transport motor  53 , and the vertical axis denotes a drive current value H and the horizontal axis denotes time t. As the waveform L illustrates, when the leading end Sf of the medium S enters the feeding roller pair  15 , the drive current value H of the transport motor  53  temporarily increases. 
     Thus, by setting a threshold value Hs 1 , it is possible to detect that the leading end Sf of the medium S enters the feeding roller pair  15 . In addition, when a threshold value Hs 2  is set, it is possible to detect whether the thickness of the medium S that has entered exceeds a predetermined thickness. Predetermined values such as the threshold values Hs 1  and Hs 2  are stored in the flash ROM  55  (refer to  FIG. 5 ). 
       FIG. 7  illustrates a first control example performed by the controller  50 . In  FIG. 7 , the controller  50  determines whether the drive current value H of the transport motor  53  exceeds the threshold value Hs 1  (Step S 101 ), and, when the drive current value H exceeds the threshold value Hs 1  (“Yes” in Step S 101 ), the controller  50  emits a notification sound (Step S 102 ). The notification sound can be a short beep such as a “pip” sound. Thus, it is possible for a user to know that the leading end Sf of the medium S is nipped by the feeding roller pair  15 . The notification sound can be issued from a speaker, which is not illustrated, provided in the operation panel  6  (refer to  FIG. 1 ). 
     Next, the controller  50  waits for a predetermined time (Step S 103 ), and, thereafter, the controller  50  positions the medium S at a printing start position by rotating the transport motor  53 , that is, by rotating the feeding roller  15   a  forward by a predetermined amount (Step S 104 ). 
     When the second medium detection portion  60  does not detect the leading end Sf of the medium S within a predetermined time (“No” in Step S 105 ), the controller  50  causes the operation panel  6  to issue an alert. The alert in such a case can be, for example, an error massage such as “Paper is jammed. Remove the jammed paper”. 
     Next,  FIG. 8  illustrates a second control example performed by the controller  50 . In the second control example, the first medium detection portion  59  provided upstream of the feeding roller pair  15  is used. 
     First, when the first medium detection portion  59  detects the leading end Sf of the medium S (“Yes” in Step S 201 ), the controller  50  determines whether the drive current value H of the transport motor  53  exceeds the threshold value Hs 1  (Step S 202 ). When the drive current value H of the transport motor  53  does not exceed the threshold value Hs 1  (“No” in Step S 202 ), the controller  50  determines whether the time that has elapsed from the first medium detection portion  59  detecting the leading end Sf of the medium S exceeds a predetermined first set time (Step S 207 ). As a result, in a case in which the time that has elapsed exceeds the predetermined first set time (“Yes” in Step S 207 ), the controller  50  causes the operation panel  6  to issue a first alert. The first alert in such a case can be, for example, an error message such as “Paper is not properly set. Reset the paper”. 
     Next, when the drive current value H of the transport motor  53  exceeds the threshold value Hs 1  (“Yes” in Step S 202 ), the controller  50  emits a notification sound (Step S 203 ). The notification sound is similar to the notification sound in Step S 102  in  FIG. 7 . 
     Next, the controller  50  waits for a predetermined time (Step S 204 ), and, thereafter, the controller  50  positions the medium S at the printing start position, by rotating the transport motor  53 , that is, by rotating the feeding roller  15   a  forward by a predetermined amount (Step S 205 ). 
     When the second medium detection portion  60  does not detect the leading end Sf of the medium S within the second set time (“No” in Step S 206 ), the controller  50  causes the operation panel  6  to issue a second alert. The alert in such a case can be, for example, an error massage such as “Paper is jammed. Remove the jammed paper”. 
     In a case of measuring the drive current value H varying in accordance with the drive load of the transport motor  53 , for example, when the power of the printer  1  is turned on, the controller  50  performs measurement processing in which the relation between a rotation load applied to the transport motor  53  and the drive current value H is measured. 
     When a reference value H 0  is a drive current value in a case of rotating the transport motor  53  in a standby state in which the medium S is not fed, the reference value H 0  varies in accordance with various factors such as specific differences of the printer  1 , operating environment of the printer  1 , and degradation over time. For example, when the reference value H 0  increases due to degradation of the apparatus over time, the difference between the reference value H 0  and the threshold value Hs 1  decreases, and erroneous detection may be caused when whether the leading end Sf of the medium S enters the feeding roller pair  15  is detected. 
     Thus, the controller  50  may obtain the reference value H 0  by performing the measurement processing and may adjust the threshold value Hs 1  based on the reference value H 0 . Other than when the power of the printer  1  is turned on as with the above-described case, the above-described measurement processing can also be performed when each recording job is performed or when a predetermined time has elapsed from the last measurement processing. 
     As described above, the medium feeding device  14  includes the feeding roller  15   a  that is provided in the medium feeding path T 3  through which the medium S is fed and that feeds the medium S downstream by rotating in the forward direction in response to power from the transport motor  53 . Based on an increase in the drive current value H, which is an example of the variation value varying in accordance with the drive load of the transport motor  53 , the controller  50  controls the transport motor  53  and causes the feeding roller  15   a  to start the medium feeding operation. 
     Thus, it is possible to suppress the feeding operation from starting in a state in which a medium S setting error occurs. As a result, when a feeding anomaly occurs after the feeding operation of the medium S starts, it is possible to issue a user an appropriate alert. Thus, user convenience can be improved. 
     In addition, when detecting an increase in the drive current value H of the transport motor  53 , the controller  50  emits a notification sound. Thus, due to the notification sound, the user can know that the medium S is nipped by the feeding roller pair  15 , and user convenience is thereby improved. 
     In the second control example in  FIG. 8 , when the first medium detection portion  59  detects the leading end Sf of the medium S (“Yes” in Step S 201 ), the controller  50  may counter-rotate the transport motor  53 , that is, the feeding roller  15   a , and, while continuing such counter-rotation, the controller  50  may monitor whether the drive current value H of the transport motor  53  exceeds the threshold value Hs 1 . Thus, an increase in the drive current value H becomes noticeable, and it is thereby possible to detect with greater certainty that the leading end Sf of the medium S is nipped by the feeding roller pair  15 . 
     The rotational speed of the feeding roller  15   a  when the feeding roller  15   a  is rotated in the reverse direction may be lower than the rotational speed of the feeding roller  15   a  when the feeding roller  15   a  is rotated in the forward direction to feed the medium S. Thus, damage to the leading end Sf of the medium S when the leading end Sf enters the feeding roller pair  15  can be suppressed from being caused. 
     In addition, in the above-described second control example, when the controller  50  does not detect an increase in the drive current value H, even if a predetermined time has elapsed from the first medium detection portion  59  detecting passage of the leading end Sf of the medium S (“Yes” in Step S 207  in  FIG. 8 ), the controller  50  emits the first alert prompting insertion of the medium S. Thus, it is possible to encourage a user to take appropriate action, and, by extension, user convenience is improved. 
     In the above-described first control example and second control example, when detecting an increase in the drive current value H, the controller  50  may cause the adjustment mechanism  49  to widen the gap between the medium supporting portion  18  and the recording head  17 . Thus, when a thick medium S is fed, it is possible to avoid the medium S rubbing against the recording head  17  and avoid damage to the recording head  17 . 
     When the gap between the medium supporting portion  18  and the recording head  17  is widened, the gap may be widened to be the maximum gap or may alternatively be widened to be a gap that is narrower than the maximum gap but with which a predetermined level of safety is expected. 
     Instead of the above-described case, when the unit detection portion  61  detects detachment of the reverse unit  24  (refer to  FIG. 3 ) from the apparatus main body  2 , the controller  50  may also widen the gap between the medium supporting portion  18  and the recording head  17 . In such a case, as with the above-described case, the gap between the medium supporting portion  18  and the recording head  17  may be widened to be the maximum gap or may alternatively be widened to be a gap that is narrower than the maximum gap but with which a predetermined level of safety is expected. 
     In addition, before the recording head  17  starts the recording operation, the controller  50  may also adjust the gap between the medium supporting portion  18  and the recording head  17  in accordance with the drive current value H. As described with reference to  FIG. 6 , because an amount of increase in the drive current value H varies in accordance with the thickness of the medium S, for example, after the gap between the medium supporting portion  18  and the recording head  17  is widened to be the maximum gap, the gap between the medium supporting portion  18  and the recording head  17  is reduced to match the thickness of the medium S based on the drive current value H. Thus, appropriate recording quality can be achieved. 
     The controller  50  may also adjust the recording quality in accordance with the thickness of the medium S grasped based on the drive current value H. For example, even if the type of the medium S that is obtained from the driver information is glossy paper and when the thickness of the medium S that is grasped based on the drive current value H corresponds to the thickness of plain paper, the recording quality may be adjusted to match the plain paper. Conversely, even if the type of the medium S that is obtained from the driver information is plain paper and when the thickness of the medium S that is grasped based on the drive current value H corresponds to the thickness of glossy paper, the recording quality may be adjusted to match the glossy paper. When the type of the medium S that is obtained from the driver information and the thickness of the medium S that is grasped based on the drive current value H do not match each other, instead of adjusting the recording quality, an alert to notice such circumstances may be displayed on the operation panel  6 . 
     The present disclosure is not limited to the above-described exemplary embodiments, various modifications can be made within the scope of the disclosure as stated in the claims, and note that such modifications are included in the scope of the present disclosure.