Patent Publication Number: US-8967790-B2

Title: Sheet cutting device and image forming apparatus including the sheet cutting device

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This patent application is based on and claims priority pursuant to 35 U.S.C. §119 to Japanese Patent Application No. 2010-268563, filed on Dec. 1, 2010, in the Japanese Patent Office, the entire disclosure of which is hereby incorporated by reference herein. 
     TECHNICAL FIELD 
     This disclosure relates to a sheet cutting device and an image forming apparatus including the sheet cutting device, and more specifically to a sheet cutting device to cut a rolled sheet to a desired length and an image forming apparatus, such as a printer, a copier, and a facsimile machine, including the sheet cutting device. 
     DESCRIPTION OF THE BACKGROUND ART 
     Image forming apparatuses are used as printers, facsimile machines, copiers, plotters, or multi-functional devices having two or more of the foregoing capabilities. As a conventional type of image forming apparatus, an image forming apparatus is known that feeds a long-size rolled sheet (hereinafter, rolled sheet) in a certain feed direction (hereinafter, sheet feed direction) to form an image on the rolled sheet. 
     The image forming apparatus typically has a sheet cutting device to cut the rolled sheet to a desired length by moving a cutter in a direction perpendicular to the sheet feed direction (hereinafter, width direction). The cutter used in the sheet cutting device may be, for example, a pair of circular blades to cut sheets of different thicknesses or materials. In particular, recently, such cutters are widely used in inkjet-type image forming apparatuses capable of forming images on sheets of different thicknesses or materials. 
     Such a conventional sheet cutting device having the pair of circular blades as the cutter needs to return a cutter holder holding the cutter to an initial position (home position) in preparation for the next sheet cutting. At this time, if a forward path along which the cutter moves to cut the sheet is identical to a backward path along which the cutter moves to return to the home position, the cutter contacts the already-cut sheet on the backward path, thus hampering movement of the cutter holder (so-called “cut jam”) or causing other failure. 
     To prevent such a cut jam or other failure, for example, JP-2009-214200-A proposes a sheet cutting device in which the backward path of the cutter formed with the pair of circular blades differs from the forward path of the cutter. Relative to the forward path, the backward path is arranged at a downstream side in the sheet feed direction in which the sheet is fed along a sheet feed path and at a position away from a leading edge of a subsequent divided sheet upstream from the cutter in the sheet feed direction. Specifically, after the cutter finishes the cutting operation, the cutter holder is tilted toward the downstream side in the sheet feed direction around a guide member for guiding the movement of the cutter holder. Thus, the position of the cutter moving along the backward path in the sheet feed direction is shifted to the downstream side in the sheet feed direction relative to the position of the cutter moving along the forward path. 
     Such a configuration can prevent the cutter from contacting the already-cut sheet on the backward path, thus preventing a cut jam. 
     However, the sheet cutting device tilts the cutter holder toward the downstream side in the sheet feed direction to differentiate the forward path from the backward path of the cutter. As a result, the sheet cutting device requires space for the cutter holder to pivot at the downstream side in the sheet feed direction, thus increasing the size of an apparatus main unit including the sheet cutting device. 
     As described above, in the sheet cutting device, the forward path of the cutter differs from the backward path, thus preventing the cutter from contacting the already-cut sheet. However, the cutter holder still remains on the sheet feed path after cutting operation. As a result, a subsequent sheet cannot be fed from the rolled sheet until the cutter and the cutter holder return to the home position, thus hampering gains in productivity. 
     BRIEF SUMMARY 
     In an aspect of this disclosure, there is provided an improved sheet cutting device including a cutter, a cutter holder, and a guide member. The cutter includes opposed blades opposing each other with a sheet interposed therebetween to cut the sheet to a desired length. The sheet is fed along a sheet feed path to the sheet cutting device. The cutter holder holds the cutter and is reciprocally movable in a width direction of the sheet perpendicular to a sheet feed direction in which the sheet is fed along the sheet feed path to the sheet cutting device. The guide member includes a first path to guide the cutter holder in the width direction of the sheet to cut the sheet with the cutter and a second path to guide the cutter holder in the width direction of the sheet after the sheet is cut with the cutter. The second path is disposed away from the first path in a thickness direction of the sheet perpendicular to both the sheet feed direction and the width direction of the sheet. When the cutter holder moves along the second path, the cutter holder is retracted away from the sheet feed path in the thickness direction of the sheet. 
     In another aspect of this disclosure, there is provided an improved image forming apparatus including an image forming device to form an image on a sheet, a sheet feed device to feed the sheet along a sheet feed path, and a sheet cutting device to cut the sheet fed along the sheet feed path. The sheet cutting device includes a cutter, a cutter holder, and a guide member. The cutter includes opposed blades opposing each other with the sheet interposed therebetween to cut the sheet to a desired length. The cutter holder holds the cutter and is reciprocally movable in a width direction of the sheet perpendicular to a sheet feed direction in which the sheet is fed along the sheet feed path to the sheet cutting device. The guide member includes a first path to guide the cutter holder in the width direction of the sheet to cut the sheet with the cutter and a second path to guide the cutter holder in the width direction of the sheet after the sheet is cut with the cutter. The second path is disposed away from the first path in a thickness direction of the sheet perpendicular to both the sheet feed direction and the width direction of the sheet. When the cutter holder moves along the second path, the cutter holder is retracted away from the sheet feed path in the thickness direction of the sheet. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The aforementioned and other aspects, features, and advantages of the present disclosure would be better understood by reference to the following detailed description when considered in connection with the accompanying drawings, wherein: 
         FIG. 1  is a schematic perspective view of an inkjet recording apparatus including a sheet cutting device according to an exemplary embodiment of this disclosure; 
         FIG. 2  is a schematic side view of the inkjet recording apparatus illustrated in  FIG. 1 ; 
         FIG. 3  is a schematic back view of the sheet cutting device according to an exemplary embodiment of this disclosure; 
         FIG. 4A  is a cross-sectional side view of a portion of the sheet cutting device;  FIG. 4B  is a cross-sectional plan view of a portion of the sheet cutting device; 
         FIG. 5  is a schematic view of a cutter holder of the sheet cutting device having returned to a rolled-sheet cutting area; 
         FIG. 6  is a schematic view of the cutter holder shifting to a backward path; 
         FIG. 7  is a cross-sectional side view of the portion of the sheet cutting device illustrated in  FIG. 4A  when the cutter holder shifts to the backward path; 
         FIG. 8  is a schematic view of the cutter holder moving along the backward path; 
         FIG. 9  is a schematic view of the cutter holder returning from the backward path to a home position; 
         FIG. 10  is a schematic view of the cutter holder returning to the rolled-sheet cutting area; 
         FIG. 11  is a schematic side view of a sheet cutting device according to an exemplary embodiment of this disclosure; and 
         FIG. 12  is a schematic side view of a sheet cutting device according to an exemplary embodiment of this disclosure. 
     
    
    
     The accompanying drawings are intended to depict exemplary embodiments of the present disclosure and should not be interpreted to limit the scope thereof. The accompanying drawings are not to be considered as drawn to scale unless explicitly noted. 
     DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS 
     In describing embodiments illustrated in the drawings, specific terminology is employed for the sake of clarity. However, the disclosure of this patent specification is not intended to be limited to the specific terminology so selected and it is to be understood that each specific element includes all technical equivalents that operate in a similar manner and achieve similar results. 
     Although the exemplary embodiments are described with technical limitations with reference to the attached drawings, such description is not intended to limit the scope of the invention and all of the components or elements described in the exemplary embodiments of this disclosure are not necessarily indispensable to the present invention. 
     Referring now to the drawings, wherein like reference numerals designate identical or corresponding parts throughout the several views, exemplary embodiments of the present disclosure are described below. 
       FIGS. 1 to 12  show a sheet cutting device and an image forming apparatus according to exemplary embodiments of the present disclosure. In  FIGS. 1 to 12 , an inkjet recording apparatus is illustrated as an example of the image forming apparatus. 
     In  FIG. 1 , an inkjet recording apparatus  1  serving as the image forming apparatus is a serial-type inkjet recording apparatus that moves an inkjet head in a width direction (hereinafter, sheet width direction) of a sheet for scanning to form an image on the sheet. After one or more scans are performed to form a line of the image, the inkjet recording apparatus  1  feeds the sheet forward a certain distance to form another line of the image. The image forming apparatus is not limited to the serial-type inkjet recording apparatus but may be, for example, a line-type inkjet recording apparatus having a recording head in which multiple nozzles are arranged across a substantially whole area in the width direction of a sheet to record an image on the sheet without scanning in the width direction. 
     The inkjet recording apparatus  1  includes an image forming section  2  serving as an image forming device, a sheet feed section  3  serving as a sheet feed device, a rolled sheet storage section  4 , and a sheet cutting device  5 . The image forming section  2 , the sheet feed section  3 , the rolled sheet storage section  4 , and the sheet cutting device  5  are disposed within an apparatus main unit  1   a.    
     In the image forming section  2 , a guide rod  13  and a guide rail  14  are extended between side plates, and a carriage  15  is supported by the guide rod  13  and the guide rail  14  so as to be slidable in a direction indicated by an arrow A. 
     The carriage  15  holds liquid ejection heads (recording heads)  16  to eject ink droplets of, e.g., black (K), yellow (Y), magenta (M), and cyan (C). Sub tanks  17  are integrally provided with the corresponding recording heads  16  to supply color inks to the recording heads  16 . 
     A main scanning mechanism  10  moves the carriage  15  for scanning in a main scanning direction, that is, the sheet width direction indicated by the arrow A. The main scanning mechanism  10  includes a driving motor  21  disposed at a first end in the sheet width direction, a driving pulley  22  rotated by the driving motor  21 , a driven pulley  23  disposed at a second end opposite the first end in the sheet width direction, and a belt member  24  looped around the driving pulley  22  and the driven pulley  23 . A tension spring tensions the driven pulley  23  outward, that is, away from the driving pulley  22 . A portion of the belt member  24  is fixed to and held by a belt fixing portion at a rear side of the carriage  15  to draw the carriage  15  in the sheet width direction. 
     To detect a main scanning position of the carriage  15  in the main scanning direction, an encoder sheet is disposed along the sheet width direction in which the carriage  15  moves. An encoder sensor disposed at the carriage  15  reads the encoder sheet to detect the main scanning position of the carriage  15 . 
     In a recording area of a main scanning region of the carriage  15 , the rolled sheet  30  is intermittently fed by the sheet feed section  3  in a direction perpendicular to the sheet width direction, that is, the sheet feed direction indicated by an arrow B in  FIG. 1 . 
     Outside a range of movement of the carriage  15  in the sheet width direction or at a first end side of the main scanning region of the carriage  15 , main cartridges  18  are removably mounted to the apparatus main unit la to store the respective color inks to be supplied to the sub tanks  17  of the recording heads  16 . At a second end side of the main scanning region opposite the first end side, a maintenance unit  19  is disposed to maintain and recover desirable conditions of the recording heads  16 . 
     The rolled sheet storage section  4  serves as a sheet feed unit into which the rolled sheet  30  serving as a sheet material for image recording is set. As the rolled sheet  30 , rolled sheets of different widths can be set to the rolled sheet storage section  4 . The rolled sheet  30  includes a sheet shaft, and flanges  31  are mounted at opposite ends of the sheet shaft. By mounting the flanges  31  to flange bearings  32  of the rolled sheet storage section  4 , the rolled sheet  30  is stored in the rolled sheet storage section  4 . The flange bearings  32  include support rollers to rotate the flanges  31  while contacting the outer circumference of the flanges  31  to feed the rolled sheet  30  to the sheet feed path. 
     As illustrated in  FIG. 2 , the sheet feed section  3  includes a pair of sheet feed rollers  33 , a registration roller  34 , and a registration pressing roller  35 . The pair of sheet feed rollers  33  feeds the rolled sheet  30  from the rolled sheet storage section  4  to the sheet feed path. The registration roller  34  and the registration pressing roller  35  are disposed upstream from the image forming section  2  in the sheet feed direction to feed the rolled sheet  30  to the sheet cutting device  5  via the image forming section  2 . 
     After the rolled sheet  30  is fed from the rolled sheet storage section  4 , the sheet feed section  3  feeds the rolled sheet  30  forward (toward the left side in  FIG. 2 ) from the rear side (right side in  FIG. 2 ) of the apparatus main unit  1   a  to the predetermined recording area below the image forming section  2 . When the rolled sheet  30  is fed to the recording area, the carriage  15  reciprocally moves back and forth in the sheet width direction and the recording heads  16  eject ink droplets in accordance with image information. In addition, while the rolled sheet  30  is intermittently fed forward, the recording heads  16  repeatedly eject ink droplets onto the rolled sheet  30  to record lines of a desired image on the rolled sheet. Thus, the whole image is formed on the rolled sheet  30  in accordance with the image information. 
     After image formation, the sheet cutting device  5  cuts the rolled sheet  30  to a desired length, and the cut sheet is discharged to a sheet output tray at the front side of the apparatus main unit  1   a.    
     Next, the sheet cutting device  5  in this exemplary embodiment is described with reference to  FIGS. 3 to 7 . 
       FIG. 3  is a schematic view of the sheet cutting device  5  seen from the back side of the apparatus main unit  1   a . The sheet cutting device  5  is disposed downstream from the image forming section  2  in the sheet feed direction (see  FIG. 2 ) and has a cutter  50 , a cutter holder  51 , and a guide member  52  as illustrated in  FIG. 3 . 
     The cutter  50  is formed with circular blades  50   a  and  50   b . The circular blades  50   a  and  50   b  are disposed opposing each other and rotatably held by the cutter holder  51 . The circular blades  50   a  and  50   b  rotate with movement of the cutter holder  51  in the sheet width direction indicated by the arrow A in  FIG. 2 . In other words, the cutter  50  rotates the circular blades  50   a  and  50   b  to cut the rolled sheet  30  and is capable of cutting, e.g., a relatively thick rolled sheet. Additionally, the cutter  50  formed with the circular blades prevents a failure, such as uneven wearing of a particular portion as in a stationary blade. It is to be noted that the number of circular blades is not limited to two and may be three or more. The circular blades  50   a  and  50   b  in this exemplary embodiment serve as cutting portions. 
     The cutter holder  51  is reciprocally movable back and forth in the sheet width direction. When the cutter holder  51  moves along a forward path (indicated by an arrow FWD in  FIG. 3 ) from the second end side to the first end side of the apparatus main unit  1   a  (see  FIG. 1 ), the cutter  50  cuts the rolled sheet  30 . By contrast, when the cutter holder  51  moves along a backward path (indicated by an arrow BWD in  FIG. 3 ) from the first end side to the second end side of the apparatus main unit  1   a  (see  FIG. 1 ), the cutter holder  51  returns to an initial position (hereinafter, home position) with the cutter holder  51  retracted from the sheet feed path downward in a thickness direction (sheet thickness direction) of the sheet, that is, the vertical direction. As a result, on the backward path, the cutter holder  51  is separated from the sheet feed path (indicated by a solid line P in  FIG. 3 ) so as not to block the sheet feed path. The cutter holder  51  is controlled based on positions detected with detectors, e.g., micro switches, disposed at opposite ends in the sheet width direction. In this exemplary embodiment, the above-described forward path serves as a first path of the cutter holder and the above-described backward path serves as a second path of the cutter holder. The configuration of the cutter holder  51  is as follows. 
     The cutter holder  51  has a driving roller  51   a  and a driven roller  51   b , and holds the cutter  50  inside. The driving roller  51   a  is connected to a wire  55  extended between a pair of pulleys  54  at opposite ends of the apparatus main unit  1   a  in the sheet width direction. The wire  55  circulates in the sheet width direction via the pair of pulleys  54  rotated by a driving motor. As a result, the driving roller  51   a  is rotationally moved on an upper guide rail  61  in accordance with the circulation of the wire  55 . The cutter holder  51  is movable in the sheet width direction in accordance with the movement of the driving roller  51   a . The driven roller  51   b  is rotatably disposed away from the driving roller  51   a  in the sheet width direction. The driven roller  51   b  moves on the upper guide rail  61  along the forward path of the cutter holder  51  and on a lower guide rail  62  along the backward path. In other words, during the movement of the cutter holder  51 , the driven roller  51   b  functions as a positioning member to position the cutter holder  51  with respect to the upper guide rail  61  and the lower guide rail  62 . The positioning member of the cutter holder  51  is not limited to the driven roller  51   b  but may be, for example, a circular-arc protrusion. In this exemplary embodiment, the driven roller  51   b  serves as a positioning portion of the cutter holder. 
     On switching between the forward path and the backward path, the cutter holder  51  pivots in the vertical direction around the driving roller  51   a . Thus, the cutter holder  51  switches between a first position with which the cutter holder  51  cuts the rolled sheet  30  along the forward path and a second position with which the cutter holder  51  is retracted from the sheet feed path. 
     As illustrated in  FIG. 4A , the driving roller  51   a  and the driven roller  51   b  are offset from each other in the sheet feed direction indicated by the arrow B. Specifically, the driven roller  51   b  is arranged upstream from the driving roller  51   a  in the sheet feed direction. As a result, with the driving roller  51   a  held on the upper guide rail  61 , the driven roller  51   b  is movable between the upper guide rail  61  and the lower guide rail  62 , thus allowing the cutter holder  51  to pivot around the driving roller  51   a . In  FIG. 4A , a broken line P extending in the direction indicated by the arrow B represents the sheet feed path. In this exemplary embodiment, as illustrated in  FIG. 4A , the cutter holder  51  is disposed within the width of the carriage  15  in the sheet feed direction. Alternatively, for example, the cutter holder  51  may be disposed away from the carriage  15  at the upstream or downstream side in the sheet feed direction. 
     As illustrated in  FIG. 3 , the cutter holder  51  has a slanted face  51   c  slanted at a predetermined angle from the sheet feed path (indicated by the solid line P) toward the vertical direction. The slant angle of the slanted face  51   c  is set so that the slanted face  51   c  is parallel to the sheet feed path when the cutter holder  51  moves along the backward path. 
     As illustrated in  FIG. 3 , the guide member  52  is a guide member to guide the movement of the cutter holder  51  in the sheet width direction, and includes the upper guide rail  61 , extending in the sheet width direction for a length that is at least longer than the width (sheet feed width) of the sheet feed path indicated by an arrow SW, and the lower guide rail  62  disposed away from the sheet feed path downward in the vertical direction. The guide member  52  forms the forward path of the cutter holder  51  on the upper guide rail  61  and the backward path of the lower guide rail  62  on the lower guide rail  62 . In this exemplary embodiment, the upper guide rail  61  and the lower guide rail  62  are formed as a single member (the guide member  52 ). Alternatively, the upper guide rail  61  and the lower guide rail  62  may be formed as separate members. In this exemplary embodiment, the lower guide rail  62  serves as a second rail. 
     As illustrated in  FIGS. 4A and 4B , the upper guide rail  61  has a driving-roller guide area  61   a  to guide the driving roller  51   a  in the sheet width direction and a driven-roller guide area  61   b  to guide the driven roller  51   b  so that the cutter holder  51  moves along the forward path. In this exemplary embodiment, the driving-roller guide area  61   a  and the driven-roller guide area  61   b  are formed as a single rail, that is, the upper guide rail  61 . Alternatively, the driving-roller guide area  61   a  and the driven-roller guide area  61   b  may be formed as separate rails. In this exemplary embodiment, the driving-roller guide area  61   a  of the upper guide rail  61  serves as a roller guide rail, and the driven-roller guide area  61   b  serves as a first rail. 
     At a first end side of the driven-roller guide area  61   b  in the sheet width direction, a first connection path  61   c  is formed to switch the path of the cutter holder  51  from the forward path to the backward path. As illustrated in  FIG. 6 , the first connection path  61   c  is formed at the upper guide rail  61  so as to connect the forward path (indicated by an arrow FWD) on the upper guide rail  61  to the backward path (indicated by an arrow BWD) on the lower guide rail  62 . Specifically, a predetermined portion of the upper guide rail  61  is cut out at the first end side in the sheet width direction and folded so as to slant downward at a certain angle, thus forming the first connection path  61   c . Thus, the first connection path  61   c  allows the driven roller  51   b  to move from the upper guide rail  61  to the lower guide rail  62  after the rolled sheet is cut with the cutter  50 . A lower end portion  61   d  of the upper guide rail  61  adjacent to the first connection path  61   c  is folded upward so as not to contact the driven roller  51   b  moving along the backward path. 
     As illustrated in  FIG. 5 , a moving mechanism  70  is disposed at a second end side of the driven-roller guide area  61   b  opposite the first end side in the sheet width direction. When the cutter holder  51  moves from the home position indicated by a solid line in  FIG. 10  to the opposite end in the sheet width direction, the moving mechanism  70  moves the driven roller  51   b  from the lower guide rail  62  to the upper guide rail  61 , that is, returns the cutter holder  51  to a cutting area (rolled-sheet cutting area) of the rolled sheet. 
     The moving mechanism  70  includes a second connection path  61   e  to connect the backward path on the lower guide rail  62  to the forward path on the upper guide rail  61 , and a switching hook  71  disposed adjacent to the second connection path  61   e  at the upper guide rail  61 . 
     The second connection path  61   e  is formed by cutting out a predetermined portion of the upper guide rail  61  at the second end side in the sheet width direction (see  FIG. 4B ). 
     The switching hook  71  pivots between the backward path and the second connection path  61   e  and is constantly urged downward by an urging member, e.g., a coil spring, so that a tip of the switching hook  71  contacts the lower guide rail  62 . As a result, as illustrated in  FIG. 9 , when the cutter holder  51  moves along the backward path (indicated by an arrow BWD) to the second end side in the sheet width direction, the driven roller  51   b  contacts the switching hook  71  to pivot the switching hook  71  as indicated by a broken line. In this state, when the driven roller  51   b  further moves to the second end side in the sheet width direction, the switching hook  71  is separated from the driven roller  51   b  and returned by the urging member to an initial position, that is, a position indicated by a solid line in  FIG. 9 . At the initial position indicated by the solid line in  FIG. 9 , the switching hook  71  is tilted at a predetermined angle. Thus, as illustrated in  FIG. 10 , when the cutter holder  51  returns from the backward path to the forward path, the driven roller  51   b  can shift from the lower guide rail  62  to the upper guide rail  61  via the switching hook  71 . The switching hook  71  may be, for example, a leaf spring. In such a case, the urging member is not necessary. In this exemplary embodiment, the first connection path  61   c  and the moving mechanism  70  serve as a path switching section. 
     The lower guide rail  62  guides the driven roller  51   b  of the cutter holder  51  moving along the backward path. 
     Next, operation of the sheet cutting device  5  is described with reference to  FIGS. 5 to 10 . 
     As illustrated in  FIG. 10 , before the rolled sheet  30  is cut, the cutter holder  51  is placed at the home position (indicated by the solid line in  FIG. 10 ) at the second end side in the sheet width direction. When an instruction for sheet cutting is received, by rotating the driving roller  51   a  via the wire  55  (see  FIG. 3 ), the cutter holder  51  is moved from the home position to the rolled-sheet cutting area (a position indicated by a broken line in  FIG. 10 ), and then moved along the forward path (indicated by an arrow FWD in  FIG. 10 ) to the first end side in the sheet width direction. At this time, the cutter  50  cuts the rolled sheet  30  in accordance with movement of the cutter holder  51 . 
     Next, as illustrated in  FIG. 6 , when the cutter holder  51  moves along the forward path (indicated by an arrow FWD) to the first end side in the sheet width direction across the sheet feed path (indicated by a solid line P), the cutting of the rolled sheet  30  is finished. After the cutter holder  51  moves to the first end side in the sheet width direction, the cutter holder  51  pivots downward in the vertical direction around the driving roller  51   a  under its own weight. Specifically, when the driven roller  51   b  moving on the upper guide rail  61  arrives at the first connection path  61   c , the driven roller  51   b  moves from the upper guide rail  61  to the lower guide rail  62  via the first connection path  61   c . At this time, as illustrated in  FIG. 7 , with the driving roller  51   a  retained on the upper guide rail  61 , only the driven roller  51   b  moves to the lower guide rail  62  under its own weight. As a result, in  FIG. 7 , the cutter holder  51  overlapping the sheet feed path indicated by a broken line P pivots to take a position with which the cutter holder  51  is movable along the backward path, that is, the position (indicated by a broken line in  FIG. 6 ) with which the cutter holder  51  is retracted from the sheet feed path. 
     Then, based on a position detected by a detector at the first end side in the sheet width direction, the wire  55  (see  FIG. 3 ) is circulated in reverse to rotate the driving roller  51   a  in reverse, that is, in a direction opposite a direction in which the driving roller  51   a  rotates on the forward path. Thus, as illustrated in  FIG. 8 , with the position retracted from the sheet feed path indicated by the solid line P, the cutter holder  51  moves along the backward path (indicated by an arrow BWD) to the second end side in the sheet width direction. At this time, the slanted face  51   c  is parallel to the sheet feed path and, unlike on the forward path, the cutter holder  51  is retracted downward from the sheet feed path. Thus, when the cutter holder  51  moves along the backward path, the rolled sheet  30  can be fed along the sheet feed path. 
     Next, as illustrated in  FIG. 9 , when the cutter holder  51  moves to the second end side in the sheet width direction and arrives at a position adjacent to the moving mechanism  70 , the driven roller  51   b  contacts the switching hook  71 . With the movement of the cutter holder  51 , the driven roller  51   b  pushes up the switching hook  71  as indicated by a broken line in  FIG. 9 , and moves from the backward path side (the right side of the switching hook  71  in  FIG. 9 ) to the second end side in the sheet width direction, that is, the side of the second connection path  61   e  (the left side of the switching hook  71  in  FIG. 9 ). When the driven roller  51   b  moves to the side of the second connection path  61   e , the switching hook  71  is separated from the driven roller  51   b  and returned by the urging member to the initial position, that is, the position indicated by the solid line in  FIG. 9 . 
     Thus, the reciprocal movement of the cutter holder  51  in the sheet width direction is finished. If the rolled sheet  30  is subsequently fed, the above-described reciprocal movement is repeated. 
     As described above, in the sheet cutting device according to this exemplary embodiment, when the cutter holder  51  moves along the backward path after the rolled sheet  30  is cut, the cutter holder  51  is retracted downward in the vertical direction from the sheet feed path so as to move away from the sheet feed path. Such a configuration prevents the cutter holder  51  moving along the backward path from getting across the sheet feed path in the sheet width direction, thus preventing the cutter holder  51  moving along the backward path from blocking the sheet feed path. As a result, even when the cutter holder  51  moves along the backward path, a subsequent rolled sheet  30  can be fed, thus enhancing the productivity. Additionally, the cutter holder  51  moving along the backward path is completely retracted from the sheet feed path. Such a configuration prevents the cutter  50  from contacting an already-cut sheet of the rolled sheet  30 , thus securely preventing a cut jam or other failure. 
     In the sheet cutting device according to this exemplary embodiment, the cutter holder  51  is retracted downward in the vertical direction. Such a configuration can reduce, in particular, the width of the apparatus main unit  1   a  in the sheet feed direction as compared to a conventional sheet cutting device that tilts a cutter holder toward a downstream side in a sheet feed direction, thus reducing the size of the apparatus main unit  1   a.    
     In the sheet cutting device according to this exemplary embodiment, on switching from the forward path to the backward path, the driven roller  51   b  moves from the upper guide rail  61  to the lower guide rail  62  to pivot in the vertical direction around the driving roller  51   a . As a result, after the rolled sheet  30  is cut, the cutter holder  51  can be retracted in the vertical direction relative to the sheet feed path. Thus, the cutter holder  51  can move along the backward path in a state in which the cutter holder  51  is retracted relative to the sheet feed path. 
     In this exemplary embodiment, the sheet cutting device includes the moving mechanism  70  to move the driven roller  51   b  from the lower guide rail  62  to the upper guide rail  61  when the cutter holder  51  moves to the second end in the sheet width direction via the backward path. Thus, the moving path of the cutter holder  51  can be switched from the backward path to the forward path by the moving mechanism  70 . 
     In the sheet cutting device according to this exemplary embodiment, the moving mechanism  70  is simply formed with the second connection path  61   e  and the switching hook  71 . Thus, the cutter holder  51  can return from the backward path to the forward path without using a complex mechanism. 
     In this exemplary embodiment, the sheet cutting device employs the rotationally driven roller  51   b  as a positioning member to position the cutter holder  51 , thus allowing smooth movement of the cutter holder  51  in the sheet width direction. 
     In the sheet cutting device according to this exemplary embodiment, the cutter holder  51  has the slanted face  51   c  slanted at a predetermined angle. Such a configuration can reduce the pivot amount of the cutter holder  51  on switching between the forward path and the backward path, thus reducing the size of the apparatus main unit  1   a.    
     In the sheet cutting device according to this exemplary embodiment, the upper guide rail  61  and the lower guide rail  62  are formed as a single member, thus reducing the cost of components. 
     In this exemplary embodiment, as illustrated in  FIG. 4A  or  4 B, the driving roller  51   a  is disposed at only one side of the cutter holder  51 , that is, a downstream side of the cutter holder  51  in the sheet feed direction. Alternatively, for example, as illustrated in  FIG. 11 , another driving roller  51   d  may be disposed at the opposite side of the cutter holder  51 . In  FIG. 11 , the driving roller  51   a  and the driving roller  51   d  oppose each other across the cutter holder  51 . In such a case, beside the upper guide rail  61  at the downstream side from the cutter holder  51  in the sheet feed direction, another guide rail  63  corresponding to the driving roller  51   d  is disposed at the upstream side from the cutter holder  51  in the sheet feed direction. In other words, two rails for guiding the driving roller  51   a  and the driving roller  51   d  are arranged in two lines parallel to the direction perpendicular to the sheet feed direction, that is, the sheet width direction. The driving roller  51   a  and the driving roller  51   d  serve as a first driving roller and a second driving roller, respectively, and the guide rail  63  serves as a second roller guide rail. 
     In this exemplary embodiment, the cutter holder  51  has the driving roller  51   a  at the first end side in the sheet width direction and the driven roller  51   b  at the second end side in the sheet width direction. However, the configuration of the cutter holder  51  is not limited to such a configuration, and for example, the positions of the driving roller  51   a  and the driven roller  51   b  are interchangeable. In such a case, the cutter holder  51  pivots in a direction opposite the pivot direction of the above-described exemplary embodiment. Accordingly, the arrangement of the slanted face  51   c  is modified according to the pivot direction. 
     In this exemplary embodiment, the cutter holder  51  is retracted downward in the vertical direction. Alternatively, for example, in a case in which the sheet cutting device  5  is not horizontally disposed relative to the apparatus main unit  1   a , the cutter holder  51  may be retracted in the thickness direction of the rolled sheet  30  in accordance with the inclination of the sheet cutting device  5 . Furthermore, as illustrated in  FIG. 12 , a cutter holder  151  may be retracted upward in the vertical direction. In such a case, a guide member  152  is disposed above the sheet feed path P. A forward path of the cutter holder  151  is disposed on a lower guide rail  162 , and a backward path of the cutter holder  151  is disposed on an upper guide rail  161 . As a result, after the cutter holder  151  moves along the forward path to cut the rolled sheet, a driven roller  151   b  moves onto the upper guide rail  161  via a moving mechanism corresponding to the moving mechanism  70  of the above-described exemplary embodiment. Thus, the cutter holder  151  is retracted from the sheet feed path so as to be movable along the backward path. After the cutter holder  151  moves along the backward path, the driven roller  151   b  moves onto the lower guide rail  162  via a communication channel corresponding to the first connection path  61   c  of the above-described exemplary embodiment. Thus, the cutter holder  151  takes a position for cutting the rolled sheet. Such a configuration can obtain effects equivalent to the effects described in the above-described exemplary embodiment. 
     Numerous additional modifications and variations are possible in light of the above teachings. It is therefore to be understood that, within the scope of the appended claims, the present disclosure may be practiced otherwise than as specifically described herein. With some embodiments having thus been described, it will be obvious that the same may be varied in many ways. Such variations are not to be regarded as a departure from the scope of the present disclosure and appended claims, and all such modifications are intended to be included within the scope of the present disclosure and appended claims.