Patent Publication Number: US-11027937-B2

Title: Moving gate for guiding print media

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is a continuation of International Application PCT/KR2017/014529 filed on Dec. 12, 2017, which claims the priority benefit of Korean Patent Application No. 10-2016-0168718, filed on Dec. 12, 2016. Both the International Application and the Korean Patent Application are incorporated by reference herein in their entirety. 
    
    
     BACKGROUND 
     A print medium finishing apparatus aligns print media on which images are formed by an image forming apparatus. The print medium finishing apparatus may perform post-processing such as hole-punching, bookbinding, etc. on the print media. 
     Such a print medium finishing apparatus includes a print medium loading device on which print media, with respect to which printing has been completed by the image forming apparatus, are loaded. The print medium loading device includes a transporting roller unit that transports a print medium, and a loading unit on which the transported print medium is loaded. 
    
    
     
       DESCRIPTION OF DRAWINGS 
       Various examples will be described below in conjunction with the accompanying drawings in which: 
         FIG. 1  is a front view of an image forming system according to an example; 
         FIG. 2A  is a perspective view for explaining components of a print medium loading device according to an example; 
         FIG. 2B  is a cross-sectional view of the print medium loading device of  FIG. 2A  according to an example; 
         FIGS. 3A-3G  are cross-sectional views for explaining a print medium loading device according to an example; 
         FIG. 4  is a perspective view of a print medium loading device including a structure for moving a moving gate of  FIGS. 3A-3G  according to an example; 
         FIG. 5A  is a magnified perspective view of one end of the moving gate of  FIG. 4  according to an example; 
         FIG. 5B  is a magnified perspective view for explaining a guide structure arranged on one end of the moving gate according to an example; 
         FIG. 5C  is a view illustrating a cross section of  FIG. 5B  according to an example; 
         FIGS. 6A-6E  are cross-sectional views for explaining an operation of the print medium loading device of  FIG. 4  according to an example; 
         FIG. 7  is a perspective view for explaining a print medium loading device according to an example; 
         FIGS. 8A and 8B  are magnified perspective views of a portion of the print medium loading device of  FIG. 7  viewed at different angles according to an example; 
         FIG. 9A  is a perspective view of one end of the moving gate of  FIG. 7  according to an example; 
         FIG. 9B  is a perspective view of the power transmit unit of  FIG. 7  according to an example; 
         FIG. 9C  is a perspective view of the power transmit unit connected to the one end of the moving gate according to an example; 
         FIGS. 10A-10D  are cross-sectional views for explaining a relationship among a second protrusion, a guide hole, and a power transmit unit, according to an example; and 
         FIGS. 11A-11E  are cross-sectional views for explaining movements of a moving gate, according to an example. 
     
    
    
     DETAILED DESCRIPTION OF EXAMPLES 
     Hereinafter, features and effects of examples of the disclosure will be described more fully with reference to the accompanying drawings, in which examples of the disclosure are shown. 
     Terms used herein will be described briefly, and examples of the present disclosure will be described in more detail. 
     Although general terms presently used were selected for describing examples of the present disclosure in consideration of the functions thereof, these general terms may vary according to intentions of one of ordinary skill in the art, case precedents, the advent of new technologies, or the like. Terms arbitrarily selected by the applicant may also be used in a specific case. In this case, their meanings need to be given in the description of the disclosure. Hence, the terms must be defined based on their meanings and the contents of the entire specification, not by simply stating the terms. 
     The terms “comprises” and/or “comprising” or “includes” and/or “including” when used in this specification, specify the presence of stated elements, but do not preclude the presence or addition of one or more other elements. 
     It will be understood that although the terms “first,” “second,” etc. may be used herein to describe various components, these components should not be limited by these terms. These components are only used to distinguish one component from another. 
     Examples of the present disclosure will now be described more fully with reference to the accompanying drawings, in which examples of the disclosure are shown. The disclosure may, however, be embodied in many different forms and should not be construed as being limited to the examples set forth herein. In the drawings, parts irrelevant to the description are omitted for simplicity of explanation, and like numbers refer to like elements throughout. 
       FIG. 1  is a front view of an image forming system according to an example. 
     Referring to  FIG. 1 , an image forming system  1  includes an image forming apparatus  20  and a print medium finishing apparatus  10 . The image forming apparatus  20  forms an image on at least one surface of a print medium. The print medium on which an image has been formed by the image forming apparatus  20  is transmitted to the print medium finishing apparatus  10 . 
     The print medium finishing apparatus  10  aligns and loads a plurality of print media on which images have been formed by the image forming apparatus  20 . 
     The print medium finishing apparatus  10  includes a print medium loading device  100  that loads the plurality of print media. In the print medium loading device  100 , the plurality of print media may be aligned in order, and a stapling operation, a hole punch operation, or the like may be conducted on the print media. 
     As shown in  FIG. 1 , the print medium finishing apparatus  10  may be, but is not limited to, an independent component that is separate from the image forming apparatus  20 . For example, although not shown, the print medium finishing apparatus  10  may be disposed abutting or connected to the image forming apparatus  20  to serve as a component of the image forming apparatus  20 . 
       FIG. 2A  is a perspective view for explaining components of a print medium loading device according to an example, and  FIG. 2B  is a cross-sectional view of the print medium loading device of  FIG. 2A  according to an example. 
     Referring to  FIGS. 2A and 2B , the print medium loading device  100  may include a transporting roller unit  110 , a loading unit  130 , and a moving gate  200 . The print medium loading device  100  may further includes a print medium guide  150 . 
     The print medium guide  150  may guide a print medium such that a leading end of the print medium is directed toward the transporting roller unit  110 , and may guide the print medium passed through the transporting roller unit  110  such that the leading end of the print medium is directed toward the loading unit  130 . 
     The print medium guide  150  includes an upper surface guide  151  that guides an upper surface of the print medium, and a lower surface guide  153  that guides a lower surface of the print medium. The lower surface guide  153  is disposed to face a portion of the upper surface guide  151 . 
     The upper surface guide  151  includes first openings  1521  into which the transporting roller unit  110  is insertable, and second openings  1522  into which a portion of the moving gate  200  is insertable. 
     The upper surface guide  151  includes a first region  1511  extending in a first direction, a second region  1513  extending in a second direction that makes an acute angle with the first direction, and a curved region  1512  connecting the first region  1511  to the second region  1513 . The first direction may be the direction of gravity. The lower surface guide  153  is disposed to face the first region  1511 . 
     The transporting roller unit  110  is disposed on the print medium guide  150 . For example, the transporting roller unit  110  may be disposed on the first region  1511  of the upper surface guide  151 . 
     The transporting roller unit  110  includes a plurality of rollers  111  spaced apart from each other in a width direction of a print medium. The plurality of rollers  111  may be inserted into the first openings  1521  formed in the first region  1511 . 
     As the plurality of rollers  111  rotate, print media are transported in order along a transport path. 
     The print media transported by the transporting roller unit  110  are loaded on the loading unit  130 . The loading unit  130  is disposed below the transporting roller unit  110 . The loading unit  130  may be disposed at an angle to the direction of gravity. The loading unit  130  may be parallel to the second region  1513 . 
     The print media transported in order by the transporting roller unit  110  may be loaded in the order in which the print media are transported. For example, a later-transported print medium may be loaded on a print medium transported earlier and loaded on the loading unit  130 . 
     However, while a print medium is being transported and loaded on the loading unit  130 , the print medium may be bent. In this case, the print media may not be loaded in the order in which they are transported. 
     For example, a trailing end of a print medium may be above and not in contact with the loading unit  130 . When another print medium is transported while the trailing end of the print medium loaded on the loading unit  130  floats above it, a leading end of the other print medium may be inserted between the previous print medium and the loading unit  130 . In this case, a paper alignment error in which the order of the print media is changed occurs. 
     To address this paper alignment error, the print medium loading device  100  includes the moving gate  200 , which is disposed between the transporting roller unit  110  and the loading unit  130  and moves according to locations to which a print medium is transported. 
     When print media are transported by the transporting roller unit  110 , the moving gate  200  may reduce or block contact between a trailing end of a print medium earlier transported and loaded on the loading unit  130  (hereinafter, referred to as a first print medium) and a leading end of a print medium later transported by the transporting roller unit  110  (hereinafter, referred to as a second print medium). 
     When the second print medium is loaded on the loading unit  130 , the moving gate  200  may contact (e.g., press) a trailing end of the second print medium loaded on the loading unit  130  in a direction closer to the loading unit  130 . Accordingly, a print medium transported after the second print medium is transported (hereinafter, referred to as a third print medium) may avoid contact with the trailing ends of the first and second print media. This may assist with sequential loading of the plurality of print media. 
     The moving gate  200  may be a single component that performs different functions according to different locations. For example, the moving gate  200  may include a first side  211  that guides the second print medium, and a second side  212  opposite to the first side  211 . When the moving gate  200  is at a certain location, the first side  211  guides a movement of the leading end of the second print medium transported by the transporting roller unit  110 . While the moving gate  200  is moving, the second side  212  presses the trailing end of the second print medium loaded on the loading unit  130 . 
     The moving gate  200  may be a single component that moves as a unit. In other words, the moving gate  200  may not include a plurality of components of which respective movements are linked with each other. Accordingly, the moving gate  200  may not have a complicated linkage structure required by a plurality of components of which respective movements are linked with each other, and does not perform a complicated control operation for a complicated linkage structure. Therefore, the moving gate  200  and the print medium loading device  100  including the same have relatively simple structures and thus may be manufactured at low costs. 
       FIGS. 3A-3G  are cross-sectional views for explaining a print medium loading device according to an example. 
     Referring to  FIG. 3A , when a first print medium P 1  is loaded on the loading unit  130 , a second print medium P 2  is transported toward the loading unit  130  by the transporting roller unit  110 . When the second print medium P 2  is transported by the transporting roller unit  110 , the moving gate  200  is positioned at a first location  200   a.    
     When the moving gate  200  is at the first location  200   a , the moving gate  200  is overlapped by a trailing end of the first print medium P 1  and is between the first print medium P 1  and the second print medium P 2 . The first side  211  of the moving gate  200  is directed toward the second print medium P 2  and the second side  212  thereof is directed toward the first print medium P 1 . A certain space or gap exists between the moving gate  200  and the loading unit  130 . For example, a space or gap that is greater than a sum of thicknesses of the print media may exist between the moving gate  200  and the loading unit  130 . 
     Because the moving gate  200  overlaps the trailing end of the first print medium P 1 , the moving gate  200  may reduce or block contact between a leading end of the second print medium P 2  and the trailing end of the first print medium P 1 . At this time, the moving gate  200  may guide movement of the second print medium P 2  via the first side  211 . 
     Referring to  FIG. 3B , the leading end of the second print medium P 2  passes by the moving gate  200 , and the second print medium P 2  is loaded on the loading unit  130 . When the leading end of the second print medium P 2  moves to the same location as the leading end of the first print medium P 1  and the second print medium P 2  is loaded on the loading unit  130 , the trailing end of the second print medium P 2  overlaps the moving gate  200 . At this time, the moving gate  200  is between the trailing end of the second print medium P 2  and the trailing end of the first print medium P 1 . 
     Referring to  FIG. 3C , the moving gate  200  moves from the first location  200   a  to a second location  200   b . When the moving gate  200  is at the second location  200   b , the moving gate  200  is spaced apart from the first print medium P 1  and the second print medium P 2 . In other words, the moving gate  200  deviates from the space between the first print medium P 1  and the second print medium P 2 . Accordingly, the trailing end of the second print medium P 2  and the trailing end of the first print medium P 1  face each other. 
     However, the second print medium P 2  may have been bent due to various causes, such as an internal temperature, friction, and the like of the print medium finishing apparatus  10 . In this case, the trailing end of the second print medium P 2  may be spaced apart from the trailing end of the first print medium P 1  without being adhered thereto (i.e., without abutting the first print medium P 1 ). 
     For example, when the moving gate  200  moves from the first location  200   a  to the second location  200   b , the moving gate  200  may move parallel to a layout direction of the loading unit  130 . Accordingly, when the moving gate  200  moves from the first location  200   a  to the second location  200   b , a space or gap between the moving gate  200  and the loading unit  130  may be maintained constant. The space or gap between the moving gate  200  and the loading unit  130  is defined as a space or gap in a direction perpendicular to the layout direction of the loading unit  130 . 
     As another example, when the moving gate  200  moves from the first location  200   a  to the second location  200   b , the moving gate  200  may move in a direction that makes an acute angle with the layout direction of the loading unit  130 , so as to be away from the loading unit  130 . Accordingly, when the moving gate  200  moves from the first location  200   a  to the second location  200   b , the space or gap between the moving gate  200  and the loading unit  130  may increase. 
     As such, because a space or gap exists between the moving gate  200  and the loading unit  130 , while the moving gate  200  is moving to the second location  200   b , the moving gate  200  may not contact the first print medium P 1 , or may not press the first print medium P 1  even when contacting the first print medium P 1 . Accordingly, while the moving gate  200  is moving to the second location  200   b , the moving gate  200  may prevent misalignment or damage of the first print medium P 1 . 
     When the moving gate  200  is at the first location  200   a , even when the second print medium P 2  and the moving gate  200  contact each other, a force other than gravity is not applied between the second print medium P 2  and the moving gate  200 , and thus, while the moving gate  200  is moving to the second location  200   b , the moving gate  200  may not press a lower surface of the second print medium P 2  and may not damage the second print medium P 2 . 
     Referring to  FIGS. 3D and 3E , the moving gate  200  moves from the second location  200   b  to a third location  200   c . While the moving gate  200  is moving from the second location  200   b  to the third location  200   c , the moving gate  200  may not bump into the trailing end of the second print medium P 2 . 
     For example, as shown in  FIG. 3D , the moving gate  200  moves such that a leading end thereof is directed toward a transport path PT of the second print medium P 2 . The transport path PT of the second print medium P 2  refers to a virtual path in which the leading end of the second print medium P 2  moves. Thereafter, as shown in  FIG. 3E , the moving gate  200  may move in a direction closer to the second print medium P 2 . When the moving gate  200  moves from the second location  200   b  to the third location  200   c , the leading end of the moving gate  200  may be inserted into the second openings  1522  of the print medium guide  150 . 
     Referring to  FIG. 3E , when the moving gate  200  is at the third location  200   c , the moving gate  200  may be positioned over the transport path PT of the second print medium P 2  and may overlap the trailing end of the second print medium P 2 . The leading end of the moving gate  200  may protrude from the second openings  1522 . 
     Referring to  FIG. 3F , the moving gate  200  may move from the third location  200   c  to a fourth location  200   d . When the moving gate  200  is at the fourth location  200   d , the moving gate  200  is disposed closer to the second print medium P 2  than when the moving gate  200  is at the third location  200   c . When the second print medium P 2  is in a bent state and the moving gate  200  is at the fourth location  200   d , the moving gate  200  may contact the trailing end of the second print medium P 2 . 
     When the moving gate  200  moves from the third location  200   c  to the fourth location  200   d , the moving gate  200  may press the trailing end of the second print medium P 2  loaded on the loading unit  130  toward the loading unit  130 . During this process, the leading end of the moving gate  200  passes through the second openings  1522  of the print medium guide  150  from the outside to the inside. When the moving gate  200  is at the fourth location  200   d , the moving gate  200  may be over the first print medium P 1  and the second print medium P 2  and may overlap the trailing ends of the first and second print media P 1  and P 2 . 
     However, when the second print medium P 2  is in a non-bent state and the moving gate  200  is at the fourth location  200   d , the moving gate  200  may not contact the trailing end of the second print medium P 2 . Referring to  FIG. 3G , when the moving gate  200  is at the fourth location  200   d , a third print medium P 3  is transported by the transporting roller unit  110 . The fourth location  200   d  of the moving gate  200  may be the same as the first location  200   a.    
     The moving gate  200  overlaps the trailing ends of the first and second print media P 1  and P 2  and is between the second print medium P 2  and the third print medium P 3 . At this time, the first side  211  of the moving gate  200  is directed toward the third print medium P 3  and the second side  212  thereof is directed toward the second print medium P 2 . 
     Because the moving gate  200  overlaps the trailing ends of the first and second print media P 1  and P 2 , the moving gate  200  may reduce or block contact between a leading end of the third print medium P 3  and the trailing ends of the first and second print media P 1  and P 2 . 
     As such, as the moving gate  200  sequentially moves from the first location  200   a  to the fourth location  200   d , a plurality of print media, namely, the first, second, and third media P 1 , P 2 , and P 3 , may be sequentially loaded on the loading unit  130 . 
       FIG. 4  is a perspective view of a print medium loading device including a structure for moving a moving gate of  FIGS. 3A-3G  according to an example.  FIG. 5A  is a magnified perspective view of one end of the moving gate of  FIG. 4  according to an example.  FIG. 5B  is a magnified perspective view for explaining a guide structure arranged on the one end of the moving gate according to an example.  FIG. 5C  is a view illustrating a cross section of  FIG. 5B  according to an example.  FIGS. 6A-6E  are cross-sectional views for explaining an operation of the print medium loading device of  FIG. 4  according to an example. For convenience of explanation,  FIGS. 4-6E  omit illustration of the transporting roller unit  110  and the loading unit  130 . 
     Referring to  FIG. 4 , the print medium loading device  100  further includes guide structures  310 , and a power transmit unit  330  which transmits a driving force to the moving gate  200 . The guide structures  310  guide movement of the moving gate  200  such that the moving gate  200  sequentially repeats the first location  200   a , the second location  200   b , the third location  200   c , and the fourth location  200   d.    
     The guide structures  310  are respectively disposed on both ends of the moving gate  200  in a direction perpendicular to a movement direction of the moving gate  200 . 
     The power transmit unit  330  includes a motor  331  which is connected to at least one of the guide structures  310  respectively disposed on both ends of the moving gate  200  and generates a driving force, a crank wheel  333  which rotates with rotation of the motor  331 , and a connection link  335  which switches a rotation of the crank wheel  333  to a reciprocating motion thereof. One end of the connection link  335  is pivotably connected to the moving gate  200  and the other end thereof is pivotably connected to the crank wheel  333 . 
     Referring to  FIGS. 5A-5C , a first protrusion  231  and a second protrusion  232 , each extending in a direction perpendicular to the movement direction of the moving gate  200 , are formed on either end of the moving gate  200 . The first protrusion  231  and the second protrusion  232  are spaced apart from each other. A third protrusion  233  that pivotably supports the connection link  335  is formed on at least one of both ends of the moving gate  200 . 
     The guide structures  310  are respectively disposed on both ends of the moving gate  200  in order to guide movements of the first protrusion  231  and the second protrusion  232 . 
     Each of the guide structures  310  includes a first guide rail  311  which guides the movement of the first protrusion  231 , and a second guide rail  312  which guides the movement of the second protrusion  232 . The first guide rail  311  guides a reciprocating motion of the first protrusion  231 . The second guide rail  312  guides a circular motion of the second protrusion  232 . The second protrusion  232  may move in a circular motion counterclockwise along the second guide rail  312 . 
     The first guide rail  311  may extend to have a straight line shape. A width of the first guide rail  311  may correspond to a dimension (e.g., a height or a diameter) of the first protrusion  231 . 
     The second guide rail  312  includes a first section  3121  extending in a same direction as a direction in which the first guide rail  311  extends, a second section  3122  extending in a direction intersecting with the extending direction of the first section  3121 , a third section  3123  extending to intersect with the second section  3122 , and a fourth section  3124  extending to intersect with the third section  3123 . A point where the fourth section  3124  and the first section  3121  are connected to each other is referred to as a point A, a point where the first section  3121  and the second section  3122  are connected to each other is referred to as a point B, a point where the second section  3122  and the third section  3123  are connected to each other is referred to as a point C, and a point where the third section  3123  and the fourth section  3124  are connected to each other is referred to as a point D. 
     The first section  3121  and the third section  3123  may be parallel to each other. The extending direction of the first section  3121  may be the same as the extending direction of the first guide rail  311 . A width of each of the first section  3121 , the second section  3122 , the third section  3123 , and the fourth section  3124  may correspond to a dimension (e.g., a height or a diameter) of the second protrusion  232 . 
     A length of the first guide rail  311  may be equal to that of the first section  3121 . The length of the first guide rail  311  may be equal to that of the third section  3123 . 
     Back flow prevention units  3151  and  3152  may be disposed on the second guide rail  312  in order to prevent the second protrusion  232  from moving in a circular motion in a reverse direction, thereby allowing the second protrusion  232  to move in a circular motion in one direction. For example, the back flow prevention units  3151  and  3152  may be disposed on the second and fourth sections  3122  and  3124 , respectively. 
     For example, when the second protrusion  232  counterclockwise presses the back flow prevention units  3151  and  3152 , the back flow prevention units  3151  and  3152  may be lowered and thus permit the second protrusion  232  to pass. However, when the second protrusion  232  clockwise presses the back flow prevention units  3151  and  3152 , the back flow prevention units  3151  and  3152  may not be lowered and thus may restrict movement of the second protrusion  232 . 
     Referring to  FIGS. 3A, 3B, and 6A , the first protrusion  231  of the moving gate  200  is located on one end of the first guide rail  311 , and the second protrusion  232  thereof is located at the point A of the second guide rail  312 . At this time, the moving gate  200  is positioned at the first location  200   a.    
     Referring to  FIGS. 3C and 6B , as the crank wheel  333  rotates, the connection link  335  connected to the crank wheel  333  moves, and a driving force is transmitted to the moving gate  200  connected to the crank wheel  333 . 
     As the driving force is transmitted to the moving gate  200 , the first protrusion  231  of the moving gate  200  moves up to the other end of the first guide rail  311  along the first guide rail  311 , and the second protrusion  232  thereof moves to the point B along the first section  3121 . Accordingly, the moving gate  200  moves from the first location  200   a  to the second location  200   b.    
     Referring to  FIGS. 3D and 6C , as the crank wheel  333  additionally rotates, a driving force is transmitted to the moving gate  200 . At this time, because the first protrusion  231  of the moving gate  200  has reached the other end of the first guide rail  311 , movement of the first protrusion  231  is restricted, and the second protrusion  232  of the moving gate  200  moves to the point C along the second section  3122 . Accordingly, the leading end of the moving gate  200  pivots. 
     While the second protrusion  232  is moving along the second section  3122 , the back flow prevention unit  3151  is pressed by the second protrusion  232  and thus a height of the back flow prevention unit  3151  is lowered, which allows the back flow prevention unit  3151  to pass the moving gate  200 . The back flow prevention unit  3151  blocks movement of the second protrusion  232  back to the point B along the second section  3122 . 
     Referring to  FIGS. 3E and 6D , as the crank wheel  333  additionally rotates, the connection link  335  moves, and a driving force is transmitted to the moving gate  200 . Accordingly, the first protrusion  231  of the moving gate  200  moves back to the one end of the first guide rail  311  along the first guide rail  311 , and the second protrusion  232  thereof moves to the point D along the third section  3123 . Accordingly, the moving gate  200  is moved to the third location  200   c.    
     Referring to  FIGS. 3F, 3G, and 6E , as the crank wheel  333  additionally rotates when the first protrusion  231  of the moving gate  200  has reached the one end of the first protrusion  231 , movement of the first protrusion  231  is restricted, and the second protrusion  232  of the moving gate  200  moves to the point A along the fourth section  3124 . During this process, the moving gate  200  is moved from the third location  200   c  to the fourth location  200   d.    
     While the second protrusion  232  is moving along the fourth section  3124 , the back flow prevention unit  3152  is pressed by the second protrusion  232  and thus a height of the back flow prevention unit  3152  is lowered, which allows the back flow prevention unit  3152  to pass the moving gate  200 . The back flow prevention unit  3152  blocks movement of the second protrusion  232  back to the point C along the fourth section  3124 . 
       FIG. 7  is a perspective view for explaining a print medium loading device according to an example.  FIGS. 8A and 8B  are magnified perspective views of a portion of the print medium loading device of  FIG. 7  viewed at different angles according to an example. For convenience of explanation,  FIGS. 7, 8A , and  8 B omit illustration of the transporting roller unit  110  and the loading unit  130 . 
     Referring to  FIGS. 7, 8A, and 8B , a print medium loading device  100 A includes a guide structure  310 A disposed on either end of a moving gate  200 A to guide movement of the moving gate  200 A such that the moving gate  200 A sequentially has the first location  200   a , the second location  200   b , the third location  200   c , and the fourth location  200   d , an elastic member  320  providing an elastic force to the moving gate  200 A such that the moving gate  200 A moves from the first location  200   a  to the second location  200   b , and a power transmit unit  340  providing a driving force such that the moving gate  200 A moves from the second location  200   b  to the fourth location  200   d  via the third location  200   c.    
     Each of the guide structures  310 A includes the first guide rail  311  which guides the reciprocating motion of the first protrusion  231 , and a guide hole  313  which guides a circular motion of a second protrusion  232 A. The second protrusion  232 A may move in one direction in accordance with a shape of the guide hole  313 . 
     The first guide rail  311  may extend in a straight line. As described above, the width of the first guide rail  311  may correspond to a dimension (e.g., a height or a diameter) of the first protrusion  231 . 
     The shape of the guide hole  313  may be defined by a straight portion  3131  and a curved portion  3132 . For example, the shape of the guide hole  313  may be semicircular. However, the shape of the guide hole  313  is not limited thereto, and the guide hole  313  may have any of various shapes as long as it includes the straight portion  3131  and the curved portion  3132 . A width of the guide hole  313  is greater than a dimension (e.g., a height or a diameter) of the second protrusion  232 A. 
     One end of the elastic member  320  is connected to the first protrusion  231 , and the elastic member  320  provides an elastic force to the first protrusion  231  in a certain direction of the guide rail  311 . For example, the elastic member  320  may provide an elastic force in such a direction that the moving gate  200 A is kept away from the first print medium P 1  and the second print medium P 2 . The elastic member  320  may provide an elastic force such that the first protrusion  231  moves toward the other end of the first guide rail  311 . 
     The power transmit unit  340  may be configured to transmit a driving force to the second protrusion  232 A that has passed through the guide hole  313 . 
       FIG. 9A  is a perspective view of one end of the moving gate of  FIG. 7  according to an example,  FIG. 9B  is a perspective view of the power transmit unit of  FIG. 7  according to an example, and  FIG. 9C  is a perspective view of the power transmit unit connected to one end of the moving gate according to an example. 
     Referring to  FIG. 9A , the first protrusion  231  and the second protrusion  232 A of the moving gate  200 A are spaced apart from each other. A height of the second protrusion  232 A is greater than that of the first protrusion  231 . 
     Referring to  FIGS. 9B and 9C , the power transmit unit  340  includes a third guide rail  341  into which the second protrusion  232 A is inserted, and a pressurization structure  343  selectively pressing the second protrusion  232 A inserted into the third guide rail  341 . 
     The third guide rail  341  includes a first straight section  3411 , a second straight section  3412  that extends from one end of the first straight section  3411  in a direction intersecting with an extension direction of the first straight section  3411 , and a curved section  3413  connecting the first straight section  3411  to the second straight section  3412 . The first straight section  3411  and the second straight section  3412  are connected to each other at a point A 1 , the second straight section  3412  and the curved section  3413  are connected to each other at a point B 1 , and the curved section  3413  and the first straight section  3411  are connected to each other at a point C 1 . 
     The third guide rail  341  may have a fan shape. A width of each of the first straight section  3411 , the second straight section  3412 , and the curved section  3123  may correspond to a dimension (e.g., a height or a diameter) of the second protrusion  232 A. 
     The pressurization structure  343  is pivotable about a pivoting shaft X 1  and receives an elastic force to pivot in one direction. When the second protrusion  232 A is in the curved section  3413 , the pressurization structure  343  may contact the second protrusion  232 A and provide a driving force to the second protrusion  232 A. 
       FIGS. 10A-10D  are cross-sectional views for explaining a relationship among a second protrusion, a guide hole, and a power transmit unit, according to an example.  FIGS. 11A-11E  are cross-sectional views for explaining movements of a moving gate, according to an example. 
     Referring to  FIGS. 10A and 11A , the second protrusion  232 A is inserted into the curved section  3413  of the third guide rail  341  via the guide hole  313 . The pressurization structure  343  contacts the second protrusion  232 A and presses the second protrusion  232 A with a received elastic force. In this state, the power transmit unit  340  rotates counterclockwise. 
     However, because movement of the second protrusion  232 A is restricted by the straight portion  3131  of the guide hole  313 , the second protrusion  232 A may not move even when the power transmit unit  340  rotates. Thus, due to the rotation of the power transmit unit  340 , the pressurization structure  343  pivots counterclockwise, which is reverse to a direction in which the elastic force is applied. At this time, the moving gate  200 A is positioned at the first location  200   a.    
     Referring to  FIGS. 10B and 11B , as the power transmit unit  340  additionally rotates while the second protrusion  232 A is restricted by the straight portion  3131  of the guide hole  313 , the curved section  3413  rotates, and the second protrusion  232 A is located at the point C 1 . 
     Because the moving gate  200 A is receiving the elastic force from the elastic member  320 , the second protrusion  232 A moves from the point C 1  to the point A 1  along the first straight section  3411 . 
     Referring to  FIGS. 10C and 11C , as the power transmit unit  340  additionally rotates, the second straight section  3412  may be aligned with the straight portion  3131  of the guide hole  313  in the same direction. In this case, because the moving gate  200 A is receiving the elastic force from the elastic member  320 , the second protrusion  232 A is moved from the point A 1  to the point B 1  along the second straight section  3412 . Accordingly, the moving gate  200 A is positioned at the second location  200   b.    
     Referring to  FIGS. 10D and 11D , as the power transmit unit  340  additionally rotates, the second protrusion  232 A located in the curved section  3413  is pressed by the pressurization structure  343 . Because the pressurization structure  343  receives an elastic force in a direction closer to the second protrusion  232 A, the second protrusion  232 A is pressed by the pressurization structure  343  rotating with the rotation of the power transmit unit  340 , in the rotating direction of the pressurization structure  343 . Thus, the second protrusion  232 A moves along the curved portion  3132  of the guide hole  313 . 
     While the first protrusion  231  is moving along the first guide rail  311  and the second protrusion  232 A is moving along a curve of the guide hole  313 , the moving gate  200 A is positioned over the transport path PT of the second print medium P 2  and is moved to the fourth location  200   d  where the moving gate  200 A overlaps the trailing end of the second print medium P 2  loaded on the loading unit  130 , via the third location  200   c  where the moving gate  200 A overlaps the trailing end of the second print medium P 2 . 
     Referring to  FIG. 11E , while the moving gate  200  is moving from the third location  200   c  to the fourth location  200   d , the moving gate  200  presses the trailing end of the second print medium P 2  loaded on the loading unit  130  in a direction closer to the loading unit  130 . 
     A print medium finishing apparatus, an image forming system, and a print medium loading device used in the image forming system, according to an example, may prevent a paper alignment error by using a simple structure. 
     A print medium finishing apparatus, an image forming system, and a print medium loading device used in the image forming system, according to an example, may prevent disorder or damage of loaded print media by minimizing contact with the loaded print media. 
     While one or more examples have shown and described with reference to the figures, it will be understood by those of ordinary skill in the art that various changes in form and details may be made therein without departing from the spirit and scope of the inventive concept as defined by the following claims.