Patent Publication Number: US-2023148093-A1

Title: Post-processing device, method for controlling post-processing device, and non-transitory computer-readable storage medium storing program for controlling post-processing device

Description:
The present application is a continuation of U.S. patent application Ser. No. 17/305,745, filed Jul. 14, 2021, which is based on, and claims priority from JP Application Serial Number 2020-122773, filed Jul. 17, 2020, the disclosures of which are hereby incorporated by reference herein in their entirety. 
    
    
     BACKGROUND 
     1. Technical Field 
     The present disclosure relates to a post-processing device, a method for controlling the post-processing device, and a non-transitory computer-readable storage medium storing a program for controlling the post-processing device. 
     2. Related Art 
     A sheet post-processing device described in JP-A-2011-201679 includes a stapling processing section that has a stapler, a moving table on which the stapler is mounted, and a base member that holds the stapler via the moving table. A motor that serves as a driving source for the stapler is not electrically locked. 
     In the configuration described in JP-A-2011-201679, a unit that mechanically holds a post-processing section is required. Therefore, it is difficult to simplify the configuration of the post-processing device. In addition, in a configuration in which an operation of the driving source for the post-processing section in the related art is electrically kept, it is necessary to separately set a current value to be used to move the post-processing section and a current value to be used to keep the operation of the driving source, and, for example, a configuration for converting output, such as a DC-DC converter, is further required. Therefore, it is difficult to simplify the configuration. 
     Furthermore, the current value to be used to keep the operation of the driving source is lower than the current value to be used to move the post-processing section. Therefore, when post-processing is executed a plurality of times, a component of impact force caused by the operation of the post-processing section may act on the post-processing section and the position of the post-processing section may deviate. 
     SUMMARY 
     To solve the foregoing problems, according to an aspect of the present disclosure, a post-processing device includes a post-processing section that is configured to move over a mounting section on which a medium is mounted in a width direction intersecting a transport direction of the medium and that executes post-processing on the medium mounted on the mounting section, a driving section that moves the post-processing section in the width direction when supplied with a current or a voltage from a power supply, and a controller that controls an operation of the post-processing section and an operation of the driving section. The controller is configured to execute first control to move the post-processing section in the width direction by supplying a set current or a set voltage set in advance from the power supply to the driving section, second control to hold the position of the post-processing section in the width direction by supplying, to the driving section, a supply current with the same value as a value of the set current or a supply voltage with the same value as a value of the set voltage, and third control to stop the supply of the supply current or the supply voltage to the driving section. When the post-processing section executes the post-processing on the medium a plurality of times, the controller repeatedly executes the second control and the third control and causes the post-processing section to execute the post-processing during the execution of the second control. 
     To solve the foregoing problems, according to another aspect of the present disclosure, a method for controlling a post-processing device including a post-processing section that is configured to move over a mounting section on which a medium is mounted in a width direction intersecting a transport direction of the medium and that executes post-processing on the medium mounted on the mounting section, and a driving section that moves the post-processing section in the width direction when supplied with a current or a voltage from a power supply includes a moving step of moving the post-processing section in the width direction by supplying a set current or a set voltage set in advance from the power supply to the driving section, a holding step of holding the position of the post-processing section in the width direction by supplying, to the driving section, a supply current with the same value as a value of the set current or a supply voltage with the same value as a value of the set voltage, and a stopping step of stopping the supply of the supply current or the supply voltage to the driving section. When the post-processing section executes the post-processing on the medium a plurality of times, the holding step and the stopping step are repeatedly executed and the post-processing section executes the post-processing during the execution of the holding step. 
     To solve the foregoing problems, according to still another aspect of the present disclosure, a non-transitory computer-readable storage medium stores a program for controlling a post-processing device including a post-processing section that is configured to move over a mounting section on which a medium is mounted in a width direction intersecting a transport direction of the medium and that executes post-processing on the medium mounted on the mounting section, and a driving section that moves the post-processing section in the width direction when supplied with a current or a voltage from a power supply. The program causes a computer to execute a moving step of moving the post-processing section in the width direction by supplying a set current or a set voltage set in advance from the power supply to the driving section, a holding step of holding the position of the post-processing section in the width direction by supplying, to the driving section, a supply current with the same value as a value of the set current or a supply voltage with the same value as a value of the set voltage, a stopping step of stopping the supply of the supply current or the supply voltage to the driving section, and a processing step of repeatedly executing the holding step and the stopping step and causing the post-processing section to execute the post-processing during the execution of the holding step when the post-processing section executes the post-processing on the medium a plurality of times. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG.  1    is an overall view of a recording system according to a first embodiment. 
         FIG.  2    is a perspective view of a post-processing unit according to the first embodiment. 
         FIG.  3    is a block diagram of main sections of the recording system according to the first embodiment. 
         FIG.  4    is a perspective view of a stapling unit according to the first embodiment when viewed from the bottom of the stapling unit. 
         FIG.  5    is a perspective view of the stapling unit according to the first embodiment when viewed from the top of the stapling unit. 
         FIG.  6    is a plan view illustrating a state in which each of the post-processing unit according to the first embodiment and a post-processing unit according to a second embodiment has executed a stapling process on paper sheets. 
         FIG.  7 A  is a schematic diagram illustrating a state in which the post-processing unit according to the first embodiment has executed a stapling process on upper right portions of paper sheets when viewed from the back side of the paper sheets. 
         FIG.  7 B  is a schematic diagram illustrating a state in which the post-processing unit according to the first embodiment has executed the stapling process on upper left portions of paper sheets when viewed from the back side of the paper sheets. 
         FIG.  8    is a timing chart illustrating an operation of transporting paper sheets, an operation of aligning the paper sheets, an operation of a moving motor, and an operation of a stapler to execute the stapling process in the post-processing unit according to the first embodiment at each time point. 
         FIG.  9    is a timing chart illustrating the case where the post-processing unit according to the first embodiment continuously executes the stapling process on two stacks of paper sheets. 
         FIG.  10    is a flowchart illustrating a procedure for processes to be executed by the post-processing unit according to the first embodiment. 
         FIG.  11 A  is a schematic diagram illustrating a state in which the stapling process has been executed by the post-processing unit according to the first embodiment on an upper left portion of the first stack of paper sheets. 
         FIG.  11 B  is a schematic diagram illustrating, together with a comparative example, a state in which the stapling process has been executed on an upper left portion of the fortieth stack of paper sheets. 
         FIG.  11 C  is a schematic diagram illustrating, together with the comparative example, a state in which the stapling process has been executed on an upper left portion of the eightieth stack of paper sheets. 
         FIG.  12    is a schematic diagram illustrating a state in which the post-processing unit according to the second embodiment has executed a stapling process on two portions of each paper sheet. 
         FIG.  13    is a timing chart illustrating an operation of transporting paper sheets, an operation of aligning the paper sheets, an operation of a moving motor, and an operation of a stapler to execute the stapling process in the post-processing unit according to the second embodiment at each time point. 
         FIG.  14    is a flowchart illustrating a procedure for processes to be executed by the post-processing unit according to the second embodiment. 
     
    
    
     DESCRIPTION OF EXEMPLARY EMBODIMENTS 
     The present disclosure is briefly described below. 
     To solve the foregoing problems, according to a first aspect of the present disclosure, a post-processing device includes a post-processing section that is configured to move over a mounting section on which a medium is mounted in a width direction intersecting a transport direction of the medium and that executes post-processing on the medium mounted on the mounting section, a driving section that moves the post-processing section in the width direction when supplied with a current or a voltage from a power supply, and a controller that controls an operation of the post-processing section and an operation of the driving section. The controller is configured to execute first control to move the post-processing section in the width direction by supplying a set current or a set voltage set in advance from the power supply to the driving section, second control to hold the position of the post-processing section in the width direction by supplying, to the driving section, a supply current with the same value as a value of the set current or a supply voltage with the same value as a value of the set voltage, and third control to stop the supply of the supply current or the supply voltage to the driving section. When the post-processing section executes the post-processing on the medium a plurality of times, the controller repeatedly executes the second control and the third control and causes the post-processing section to execute the post-processing during the execution of the second control. 
     According to the first aspect, in the first control and the second control, the set current and the supply current have the same value or the set voltage and the supply voltage have the same value. Therefore, a converter that changes the magnitude of the supply current to be output and supplied to the driving section or the magnitude of the supply voltage to be output and supplied to the driving section is not required. Therefore, the configuration of the post-processing device can be simplified. 
     Furthermore, according to the first aspect, the post-processing is executed by the post-processing section in a state in which force to hold the post-processing section is increased by supplying, to the driving section, the supply current or the supply voltage that has the same value as the set current or the set voltage. Therefore, even when a component of impact force caused by an operation of executing the post-processing acts on the post-processing section, it is possible to suppress a deviation of the position of the post-processing section in the width direction. 
     According to a second aspect of the present disclosure, in the first aspect, when the post-processing is executed a plurality of times at a single set position in the width direction on the medium, the controller repeatedly executes the second control and the third control without executing the first control. 
     According to the second aspect, since the first control is not executed in the post-processing executed the plurality of times, a speed at which the post-processing is executed can be higher than that in a configuration in which the first control is executed every time the post-processing is to be executed. 
     According to a third aspect of the present disclosure, in the first aspect, when the post-processing is executed a plurality of times at a first position and a second position different from the first position in the width direction on the medium, the controller executes the third control at the first position and the second position. 
     According to the third aspect, when the post-processing section is present at the first position or the second position, the supply of the supply current or the supply voltage to the driving section is stopped. Therefore, it is possible to reduce power to be consumed by the post-processing device, compared to a configuration in which the supply current or the supply voltage is continuously supplied to the driving section. 
     According to a fourth aspect of the present disclosure, in any one of the first to third aspects, the controller synchronizes an operation of the post-processing section to execute the post-processing with an operation of the driving section using, as a reference time point, a time point when a signal is input before the start of the operation of the post-processing section to execute the post-processing. 
     According to the fourth aspect, since the operation of the post-processing section to execute the post-processing is synchronized with the operation of the driving section, an extra supply current or an extra supply voltage is hardly supplied, compared to a configuration in which the operations are not synchronized. Therefore, it is possible to reduce power to be consumed by the post-processing device. 
     According to a fifth aspect of the present disclosure, in any one of the first to fourth aspects, the controller starts the supply of the supply current or the supply voltage to the driving section before the start time of an operation of executing the post-processing. 
     According to the fifth aspect, before the start time of the operation of the post-processing section to execute the post-processing, force to hold the post-processing section by the driving section is increased. Therefore, when the post-processing is executed by the post-processing section, it is possible to suppress a deviation of the position of the post-processing section in the width direction. 
     According to a sixth aspect of the present disclosure, in the fifth aspect, when a set time period elapses after the start time of the supply of the supply current or the supply voltage to the driving section, the controller stops the supply of the current or the voltage to the driving section. 
     According to the sixth aspect, when the set time period elapses after the start time of the supply of the supply current or the supply voltage to the driving section, the supply of the current or the voltage from the power supply to the driving section is stopped. Therefore, it is possible to further reduce power to be consumed by the post-processing device, compared to a configuration in which the current or the voltage is supplied to the driving section for a time period longer than the set time period. 
     According to a seventh aspect of the present disclosure, in the fifth or sixth aspect, when a set elapsed time period elapses after the end time of the operation of the post-processing section to execute the post-processing, the controller stops the supply of the current or the voltage from the power supply to the driving section. 
     According to the seventh aspect, when the set elapsed time period elapses after the end time of the operation of the post-processing section to execute the post-processing, the supply of the current or the voltage from the power supply to the driving section is stopped. Therefore, it is possible to further reduce power to be consumed by the post-processing device, compared to a configuration in which the current or the voltage is supplied to the driving section for a time period longer than the set elapsed time period. 
     According to an eighth aspect of the present disclosure, in any one of the first to seventh aspects, a first time period from the end time of the post-processing to the end time of the second control is longer than a second time period from the start time of the second control to the start time of the post-processing. 
     According to the eighth aspect, since the holding of the position of the post-processing section is released after the termination of the operation of the post-processing section, it is possible to suppress a deviation of the position of the post-processing section in the width direction while reducing power to be consumed by the post-processing device. 
     According to a ninth aspect of the present disclosure, in any one of the first to eighth aspects, the controller causes the post-processing section to execute the post-processing without executing the second control in the last post-processing among the plurality of times of the post-processing. 
     Since the post-processing is not executed after the execution of the last post-processing, a problem does not occur even when the position of the post-processing section deviates in the width direction. 
     According to the ninth aspect, since the number of times that the second control is executed is reduced by 1, it is possible to reduce power to be consumed by the post-processing device, compared to a configuration in which the second control is executed every time the post-processing that is executed a plurality of times is to be executed. 
     According to a tenth aspect of the present disclosure, in any one of the first to ninth aspects, when the number of times that the post-processing is executed on a single portion of the medium is 1, the controller causes the post-processing section to execute the post-processing without executing the second control. 
     When the number of times that the post-processing is executed on a single portion of the medium is 1, the post-processing is not executed after the execution of the post-processing. Therefore, a problem does not occur even when the position of the post-processing section deviates in the width direction. 
     According to the tenth aspect, since the second control is not executed, it is possible to reduce power to be consumed by the post-processing device, compared to a configuration in which the second control is executed when the post-processing is to be executed once. 
     According to an eleventh aspect of the present disclosure, in any one of the first to tenth aspects, the post-processing section is a stapling section that staples the medium, the driving section includes a stepping motor having a coil that is excited by supplying a current to the coil, and force that acts on the stapling section in the width direction when the stapling section staples the medium is larger than holding force caused by detent torque when the coil is not excited. 
     According to the eleventh aspect, since the force that acts on the stapling section in the width direction increases, it is possible to easily move the stapling section in the width direction as a result. 
     According to a twelfth aspect of the present disclosure, a method for controlling a post-processing device including a post-processing section that is configured to move over a mounting section on which a medium is mounted in a width direction intersecting a transport direction of the medium and that executes post-processing on the medium mounted on the mounting section, and a driving section that moves the post-processing section in the width direction when supplied with a current or a voltage from a power supply includes a moving step of moving the post-processing section in the width direction by supplying a set current or a set voltage set in advance from the power supply to the driving section, a holding step of holding the position of the post-processing section in the width direction by supplying, to the driving section, a supply current with the same value as a value of the set current or a supply voltage with the same value as a value of the set voltage, and a stopping step of stopping the supply of the supply current or the supply voltage to the driving section. When the post-processing section executes the post-processing on the medium a plurality of times, the holding step and the stopping step are repeatedly executed and the post-processing section executes the post-processing during the execution of the holding step. 
     According to the twelfth aspect, it is possible to obtain the same actions and effects as those obtained by the post-processing device according to the first aspect. 
     According to a thirteenth aspect of the present disclosure, a non-transitory computer-readable storage medium stores a program for controlling a post-processing device including a post-processing section that is configured to move over a mounting section on which a medium is mounted in a width direction intersecting a transport direction of the medium and that executes post-processing on the medium mounted on the mounting section, and a driving section that moves the post-processing section in the width direction when supplied with a current or a voltage from a power supply. The program causes a computer to execute a moving step of moving the post-processing section in the width direction by supplying a set current or a set voltage set in advance from the power supply to the driving section, a holding step of holding the position of the post-processing section in the width direction by supplying, to the driving section, a supply current with the same value as a value of the set current or a supply voltage with the same value as a value of the set voltage, a stopping step of stopping the supply of the supply current or the supply voltage to the driving section, and a processing step of repeatedly executing the holding step and the stopping step and causing the post-processing section to execute the post-processing during the execution of the holding step when the post-processing section executes the post-processing on the medium a plurality of times. 
     According to the thirteenth aspect, it is possible to obtain the same actions and effects as those obtained by the post-processing device according to the first aspect. 
     First Embodiment 
     An example of a post-processing device, a method for controlling the post-processing device, and a program for controlling the post-processing device according to a first embodiment of the present disclosure is described below in detail. 
       FIG.  1    illustrates a recording system  1  that is an example of a recording device. The recording system  1  is constituted as an ink jet type device that executes recording by ejecting ink onto a paper sheet P. The paper sheet P is an example of a medium. The ink is an example of a liquid. 
     In an X-Y-Z coordinate system illustrated in each drawing, an X direction is a width direction of the device, a Y direction is a depth direction of the device, and a Z direction is a height direction of the device. The X, Y, and Z directions are perpendicular to each other. 
     When left and right sides with respect to the center in the width direction of the device when the recording system  1  is viewed from its front side are distinguished, the left side is referred to as positive X direction and the right side is referred to as negative X direction. When front and rear sides with respect to the center in the depth direction of the device are distinguished, the front side is referred to as negative Y direction and the rear side is referred to as positive Y direction. When upper and lower sides with respect to the center in the height direction of the device are distinguished, the upper side is referred to as positive Z direction and the lower side is referred to as negative Z direction. A post-processing unit  30  is described later using the foregoing directions, an A direction, and a B direction. 
     The recording system  1  includes a recording unit  2 , an intermediate unit  4 , and a post-processing unit  30  that are arranged in this order toward the positive X direction. The recording unit  2 , the intermediate unit  4 , and the post-processing unit  30  are mechanically and electrically coupled to each other in the recording system  1 . The intermediate unit  4  transports the paper sheet P fed from the recording unit  2  to the post-processing unit  30 . 
     In the recording system  1 , an operating section  15  ( FIG.  3   ) to be operated by an operator and a display section  17  ( FIG.  3   ) that displays various types of information of the recording system  1  are installed. The operating section  15  is configured to input various settings of the recording unit  2  and the post-processing unit  30 . The recording system  1  is configured to execute post-processing (described later) on the paper sheet P with information recorded by a printer section  10  (described later). In the recording system  1 , the same actions and effects as those of the post-processing unit  30  can be obtained. 
     The recording unit  2  records various types of information on the transported paper sheet P. The paper sheet P is formed in a sheet-like shape. The recording unit  2  includes the printer section  10 , a scanner section  12 , a cassette storage section  14 , and a power supply  16 . 
     The printer section  10  is an example of a recording section and includes a recording head  20 , a controller  22 , and a transport motor  23  ( FIG.  3   ). 
     The recording head  20  is configured as a line head as an example. 
     The transport motor  23  rotationally drives a plurality of pairs of rollers (not illustrated), a paddle  46  (described later), and a discharge roller  48  (described later) that are included in the recording system  1 . The transport motor  23  does not mean a single motor and is a generic term for a plurality of motors. In the following description, a motor and a motor driver are collectively referred to as “motor” and an illustration and description of the motor driver are omitted. 
     As illustrated in  FIG.  3   , the controller  22  includes a central processing unit (CPU)  24  that functions as a computer, a memory  26  that functions as a storage section, a timer  28  that can measure a time period or time based on each time point, and storage (not illustrated). The controller  22  controls various operations in the recording system  1 . The control by the controller  22  includes control of an operation of a stapling unit  50  ( FIG.  1   ) (described later) and control of an operation of a driving section  34  (described later). 
     In the memory  26 , a program PR to be executed by the CPU  24  and various data (not illustrated) are stored. The memory  26  is an example of a recording medium storing the computer-readable program PR. Other examples of the recording medium are a CD, a DVD, a Blu-ray disc, and a USB memory. The program PR can be loaded into a portion of the memory  26 . 
     The program PR causes the CPU  24  to execute a moving step of moving the post-processing unit  30  ( FIG.  1   ) (described later), a holding step of holding the post-processing unit  30 , a stopping step, and a processing step. 
     As illustrated in  FIG.  1   , the scanner section  12  reads information of an original document (not illustrated). 
     The cassette storage section  14  includes a plurality of storage cassettes  18  that store a plurality of paper sheets P. In the printer section  10  and the cassette storage section  14 , a transport path  19  on which a paper sheet P is transported is formed. On the transport path  19 , a paper sheet P is transported from the storage cassettes  18  through a recording region of the recording head  20  and the intermediate unit  4  to the post-processing unit  30 . 
     The post-processing unit  30  is an example of a post-processing device and collectively executes post-processing on a required number of paper sheets P received from the intermediate unit  4 . In the present embodiment, as an example of the post-processing, a stapling process of stapling a plurality of paper sheets P with a staple  61  ( FIG.  6   ) is executed. In other words, the stapling process is a process of stapling a plurality of paper sheets P with a staple  61  to form a stack Q of paper sheets. In the post-processing unit  30 , a transport path K on which a paper sheet P fed from the intermediate unit  4  is transported is formed. The transport path K includes a main transport path K 1  extending toward a processing tray  32  (described later) and a sub-transport path K 2  extending toward an upper tray  33  (described later) as an example. 
     As illustrated in  FIG.  2   , the post-processing unit  30  includes a housing  31  as a main body. The upper tray  33  is formed at an end portion of the housing  31  in the positive Z direction. A discharge tray  35  is disposed at an end portion of the housing  31  in the positive X direction, while the end portion of the housing  31  in the positive X direction is present in the positive Z direction. The upper tray  33  is inclined in such a manner that a portion of the upper tray  33  in the positive X direction is located at a higher position in the positive Z direction than a portion of the upper tray  33  in the negative X direction. The discharge tray  35  is inclined in such a manner that a portion of the discharge tray  35  in the positive X direction is located at a higher position in the positive Z direction than a portion of the discharge tray  35  in the negative X direction. 
     As illustrated in  FIG.  1   , the post-processing unit  30  includes the processing tray  32 , the stapling unit  50 , the driving section  34  ( FIG.  3   ), and the controller  22  as an example. The present embodiment describes a configuration in which the controller  22  also serves as a controller of the post-processing unit  30  as an example. However, the post-processing unit  30  may include its own controller. 
     In the post-processing unit  30 , alignment plates  42 , side cursors  43  and  44  ( FIG.  6   ), the paddle  46 , and the discharge roller  48  are installed. 
     The processing tray  32  is an example of a mounting section. One or multiple paper sheets P transported along the main transport path K 1  are mounted on the processing tray  32 . The processing tray  32  has a mounting surface  32 A on which one or multiple paper sheets P are mounted. The mounting surface  32 A is inclined in such a manner that a portion of the mounting surface  32 A in the positive X direction is located at a higher position in the positive Z direction than a portion of the mounting surface  32 A in the negative X direction. A direction toward which the mounting surface  32 A is inclined is referred to as A direction. 
     The A direction is an example of a transport direction of a paper sheet P and is perpendicular to the Y direction. The A direction intersects the X direction and the Z direction. When directions toward which the A direction extends are distinguished, a direction that extends toward the stapling unit  50  in the A direction is referred to positive A direction and a direction that extends toward the opposite side to the stapling unit  50  in the A direction is referred to as negative A direction. 
     The Y direction is an example of a width direction of a paper sheet P. As described above, the Y direction intersects the A direction. A direction that is perpendicular to the A direction when viewed from the Y direction is referred to as B direction. A direction toward which paper sheets P are stacked in the B direction is referred to as positive B direction, and a direction that extends toward the opposite direction to the positive B direction is referred to as negative B direction. 
     In the processing tray  32 , a sheet sensor  39  (FIG.  3 ) is installed. The sheet sensor  39  is configured as an optical reflection type sensor as an example. The sheet sensor  39  detects whether a paper sheet P is present on the processing tray  32 , thereby detecting whether the reception of the paper sheet P has been completed. A signal of information detected by the sheet sensor  39  is transmitted to the controller  22  ( FIG.  3   ). 
     The driving section  34  is described using  FIGS.  1 ,  3 ,  4 , and  6   . An operation of the driving section  34  is controlled by the controller  22 . A current or a voltage can be supplied from the power supply  16  to the driving section  34 . 
     The driving section  34  includes a guide motor  38 , a moving motor  36 , and a stapling motor  37  as an example. 
     The guide motor  38  includes a pinion (not illustrated) and drives the side cursors  43  and  44  (described later) in such a manner that the side cursors  43  and  44  become closer to or farther from each other in the Y direction. 
     The moving motor  36  is configured as a stepping motor and includes a coil  36 A. In other words, the driving section  34  includes a stepping motor having the coil  36 A that is excited by supplying a current to the coil  36 A. The moving motor  36  includes a pinion  36 B and drives transmission belts  58  and  59  (described later) to move a stapler  60  (described later) toward the positive Y direction or the negative Y direction. In other words, the driving section  34  moves the stapler  60  in the Y direction. 
     The stapling motor  37  drives the stapler  60  to cause the stapler  61  to staple a paper sheet P with a staple  61 . Specifically, the stapling motor  37  causes the stapler  61  to execute the stapling process. 
     As illustrated in  FIG.  6   , the alignment plates  42  stand upright in the B direction at end portions of the processing tray  32  in the positive A direction. The three alignment plates  42  are arranged at intervals in the Y direction as an example. The positions of paper sheets P in the A direction are determined or end portions of the paper sheets P are aligned due to contact of the end portions of the paper sheets P, which have been transported to the processing tray  32 , in the positive A direction with the three alignment plates  42 . 
     The side cursors  43  and  44  have a predetermined thickness in the Y direction and are formed in a plate-like shape. The side cursors  43  and  44  are arranged at an interval in the Y direction. For the side cursors  43  and  44 , racks (not illustrated) are provided. The racks are moved in the Y direction via the pinion of the guide motor  38  ( FIG.  3   ) in such a manner that the side cursors  43  and  44  move in the Y direction and become closer to or farther from each other to enable paper sheets P to be aligned. 
     As illustrated in  FIG.  1   , the paddle  46  is rotatable around its rotational axis extending in the Y direction and is installed in the housing  31 . The paddle  46  is driven by the transport motor  23  ( FIG.  3   ) to transport a paper sheet P to the processing tray  32 . 
     The discharge roller  48  is arranged downstream of the paddle  46  in the negative A direction. The discharge roller  48  is rotatable around its rotational axis extending in the Y direction and is installed in the housing  31 . The discharge roller  48  is driven by the transport motor  23  to discharge a paper sheet P on the processing tray  32  or a stack Q of paper sheets on the processing tray  32  to the discharge tray  35 . 
     As illustrated in  FIG.  4   , as an example, the stapling unit  50  includes a base frame  52 , guide shafts  55 , a movable frame  56 , two pulleys  57 , the transmission belts  58  and  59 , and the stapler  60 . The stapling unit  50  is arranged in the positive A direction with respect to the processing tray  32  ( FIG.  1   ). 
     The base frame  52  is opened in the negative Z direction and formed in a box-like shape. The base frame  52  includes an upper plate portion  52 A extending along an A-Y plane and side walls  52 B facing each other in the Y direction. The upper plate portion  52 A extends in the Y direction. A guide hole portion  54  is formed in the upper plate portion  52 A. In addition, the moving motor  36  is disposed on the upper plate portion  52 A. 
     The guide hole portion  54  includes a first hole portion  54 A, a second hole portion  54 B, and a third hole portion  54 C. The guide hole portion  54  is formed symmetrically with respect to the center in the Y direction. The first hole portion  54 A extends in the Y direction. The second hole portion  54 B extends in a direction intersecting and oblique to the Y direction from both end portions of the first hole portion  54 A in the Y direction. In addition, the second hole portion  54 B extends toward a position located in the negative A direction. The third hole portion  54 C extends in the Y direction from both end portions of the second hole portion  54 B toward the outer side. 
     The guide shafts  55  extend in the Y direction and are disposed between the side walls  52 B. 
     The movable frame  56  is held by the guide shafts  55  and can move along the guide shafts  55  in the Y direction. The stapler  60  is disposed on the movable frame  56  in such a manner that the stapler  60  can move relatively to the movable frame  56 . 
     The two pulleys  57  are disposed on the base frame  52 . The transmission belt  59  is wound around one of the pulleys  57  and the pinion  36 B. 
     The transmission belt  58  is wound around the two pulleys  57 . The movable frame  56  is fixed to a portion of the transmission belt  58 . 
     The pinion  36 B is rotated forward or backward to cause the movable frame  56  to linearly move toward the positive Y direction or the negative Y direction. In other words, the stapler  60  is moved toward the positive Y direction or the negative Y direction. 
     The stapler  60  is an example of a stapling section and an example of a post-processing section. As illustrated in  FIG.  5   , the stapler  60  is arranged in the positive Z direction with respect to the upper plate portion  52 A. When the stapler  60  is moved to an end portion of the first hole portion  54 A in the Y direction, the stapler  60  enters in the second hole portion  54 B while rotating and is oriented toward a direction intersecting the Y direction. 
     The position of the stapler  60  at an end portion of the base frame  52  in the positive Y direction and the position of the stapler  60  at an end portion of the base frame  52  in the negative Y direction are axisymmetric with respect to a straight line (not illustrated) extending in the A direction through the center in the Y direction. 
     The stapler  60  includes a moving section (not illustrated), a staple  61  ( FIG.  6   ), and a stapling motor  37  ( FIG.  3   ). The staple  61  is an example of a staple. The stapling motor  37  is operated by supplying a current to the stapling motor  37  and drives the moving section to cause the stapler  60  to staple portions of a plurality of paper sheets P with the staple  61 . In other words, the stapler  60  executes the stapling process on a plurality of paper sheets P to staple the paper sheets P by supplying a current. The stapler  60  is provided in such a manner that the stapler  60  can move in the Y direction. The stapler  60  executes the stapling process on a plurality of paper sheets P mounted on the processing tray  32  to form one stack Q of the paper sheets ( FIG.  1   ). The stapling process is an example of post-processing. 
     As illustrated in  FIG.  6   , the stapler  60  can be located at four positions relative to a paper sheet P when viewed from the B direction as an example. In  FIG.  6   , the four positions PA, PB, PC, and PD of the stapler  60  are indicated by virtual lines P 1 , P 2 , P 3 , and P 4  indicating an outer shape of the stapler  60 .  FIG.  6    illustrates a paper sheet P when viewed from the back side. 
     The stapler  60  executes the stapling process on upper right portions of paper sheets P at the position P 1 . Specifically, the stapler  60  staples the upper right portions of the paper sheets P with a staple  61  ( FIG.  7 A ). 
     In addition, the stapler  60  executes the stapling process on upper left portions of the paper sheets P at the position P 4 . Specifically, the stapler  60  staples the upper left portions of the paper sheets P with a staple  61  ( FIG.  7 B ). 
     Furthermore, after the stapler  60  executes the stapling process at the position P 2 , the stapler  60  is moved to the position P 3  in the Y direction and executes the stapling process to staple end portions of the paper sheets P in the positive A direction with two staples  61  in such a manner that the two staples  61  are arranged at an interval in the Y direction. 
     The first embodiment describes an example in which the stapler  60  executes the stapling process on a plurality of paper sheets P at the position P 4 . 
     Control set in advance in the controller  22  illustrated in  FIG.  3    is described below. In other words, various types of control to be executed by the controller  22  are described below. Sections of the post-processing unit  30  are described with reference to  FIGS.  1  to  6   , and a description of the individual figure numbers is omitted. 
     The controller  22  can execute first control, second control, and third control. 
     The first control is to supply a set current Ia or a set voltage Va set in advance from the power supply  16  to the moving motor  36  of the driving section  34  to cause the moving motor  36  to move the stapler  60  in the Y direction. An illustration of the set current Ia and the set voltage Va is omitted. 
     The second control is to supply a supply current Ib with the same value as a value of the set current Ia or a supply voltage Vb with the same value as a value of the set voltage Va to the moving motor  36  of the driving section  34  to cause the moving motor  36  to hold the position of the stapler  60  in the Y direction. An illustration of the supply current Ib and the supply voltage Vb is omitted. 
     The third control is to stop the supply of the supply current Ib or the supply voltage Vb to the moving motor  36  of the driving section  34 . 
     A state in which the value of the set current Ia is the same as the value of the supply current Ib includes not only a state in which Ia=Ib but also a state in which one of the values of the currents Ia and Ib is in a measurement error range of the other. Similarly, a state in which the value of the set voltage Va is the same as the value of the supply voltage Vb includes not only a state in which Va=Vb but also a state in which one of the values of the voltages Va and Vb is in a measurement error range of the other. In the execution of the program PR, the first control corresponds to the moving step, the second control corresponds to the holding step, and the third control corresponds to the stopping step. 
     When the stapler  60  executes the stapling process on paper sheets P a plurality of times, the controller  22  repeatedly executes the second control and the third control and causes the stapler  60  to execute the stapling process during the execution of the second control. This control corresponds to the processing step in the execution of the program PR. 
     When the stapling process is executed a plurality of times at one set position on paper sheets P in the Y direction, the controller  22  repeatedly executes the second control and the third control without executing the first control. 
     The controller  22  synchronizes an operation of the stapler  60  to execute the stapling process with an operation of the driving section  34  using, as a reference time point, a time point when a signal is input before the start of the operation of the stapler  60  to execute the stapling process. In the present embodiment, as an example of the reference time point, a time point when a signal transmitted from the sheet sensor  39  when the reception of a paper sheet P on the processing tray  32  of the post-processing unit  30  is terminated is input is set. 
     At a time point t 9  that is before a time point t 10  when the operation of executing the stapling process is started, the controller  22  starts supplying the supply current Ib or the supply voltage Vb to the moving motor  36  of the driving section  34 . 
     When a set time period ΔT (seconds) ( FIG.  8   ) (described later) elapses after the start time of the supply of the supply current Ib or the supply voltage Vb to the moving motor  36  of the driving section  34 , the controller  22  stops the supply of the current or the voltage to the moving motor  36  from the power supply  16 . When a set elapsed time period Δt 1  (seconds) ( FIG.  8   ) elapses after the end time of the operation of the stapler  60  to execute the stapling process, the controller  22  stops the supply of the current or the voltage to the moving motor  36  of the driving section  34  from the power supply  16 . 
     In the last stapling process among the plurality of times of the stapling process, the controller  22  causes the stapler  60  to execute the stapling process without executing the second control. 
     When the number of times that the stapling process is executed on one portion of a paper sheet P is 1, the controller  22  causes the stapler  60  to execute the stapling process without executing the second control. 
     Settings for operations of the sections of the post-processing unit  30  are described using timing charts. The sections of the post-processing unit  30  are described with reference to  FIGS.  1  to  6   , and a description of the individual figure numbers is omitted. 
       FIG.  8    is a timing chart illustrating time points when an operation of transporting paper sheets P, an operation of aligning the paper sheets P, an operation of the moving motor  36 , and an operation of executing the stapling process are on or off. The operations illustrated in  FIG.  8    are operations to be executed until the stapling process is terminated and one stack Q of the paper sheets is formed.  FIG.  8    illustrates a time period from a time point t 1  through time points t 2  to t 11  to a time point t 12 . Intervals between the time points t 1  to t 12  or lengths of time periods between the time points t 1  to t 12  are schematically illustrated and may be different from actual lengths of time periods between the time points t 1  to t 12 . 
     The operation of transporting the paper sheets P includes an operation of using the paddle  46  to transport the paper sheets P and an operation of using the discharge roller  48  to discharge the stack Q of paper sheets. The operation of transporting the paper sheets P by the paddle  46  is started at the time point t 1  and terminated at the time point t 2 . 
     The operation of aligning the paper sheets is an operation of using the side cursors  43  and  44  to align end portions of the plurality of paper sheets P in the Y direction. The operation of aligning the plurality of paper sheets P is started at the time point t 3  and terminated at the time point t 4 . 
     In the time period from the time point t 1  to the time point t 2 , the plurality of paper sheets P may be transported by the paddle  46  to the processing tray  32  and aligned by the side cursors  43  and  44 . 
     In the operation of the moving motor  36 , the set current Ia or the set voltage Va is supplied to the moving motor  36  at the time point t 5 , and the stapler  60  starts moving at the time point t 6 . The supply of the set current Ia or the set voltage Va to the moving motor  36  is stopped at the time point t 7 , and the stapler  60  is stopped moving at the time point t 8 . 
     The supply current Ib or the supply voltage Vb is supplied to the moving motor  36  at the time point t 9 . The supply of the supply current Ib or the supply voltage Vb is stopped at the time point t 12 . In other words, in a time period from the time point t 9  to the time point t 12 , the moving motor  36  resists external force in such a manner that the moving motor  36  does not rotate and thus the position of the stapler  60  in the Y direction is held. 
     As an example, the time point t 9  is set as a time point when a time period set in advance elapses after the time point t 8  as a reference time point. As an example, the time point t 12  is set as a time point when a time period set in advance elapses after the time point t 11  as a reference time point. The time period from the time point t 9  to the time point t 12  corresponds to the set time period ΔT. 
     The operation of executing the stapling process is an operation of stapling a plurality of paper sheets P by the stapler  60  with a staple  61 . The operation of executing the stapling process is started at the time point t 10  and terminated at the time point t 11 . As an example, the time point t 10  is set as a time point when a time period set in advance elapses after the time point t 8  as a reference time point. 
     In the present embodiment, as an example, in a time period for which the position of the stapler  60  in the Y direction is held, the operation of executing the stapling process is executed. 
     The time period from the time point t 11  to the time point t 12  corresponds to the first time period Δt 1 . The time period from the time point t 9  to the time point t 10  corresponds to a second time period Δt 2  (seconds). 
     Regarding the post-processing unit  30 , the first time period Δt 1  from the end time of the stapling process to the end time of the second control is longer than the second time period Δt 2  from the start time of the second control to the start time of the stapling process. The first time period Δt 1  is an example of a set elapsed time period. 
     In addition, regarding the post-processing unit  30 , force that acts on the stapler  60  in the Y direction when the stapler  60  staples paper sheets P is larger than holding force caused by detent torque when the coil  36 A of the moving motor  36  is not excited. 
       FIG.  9    is a timing chart illustrating the case where the operations illustrated in  FIG.  8    are continuously executed on two stacks Q of paper sheets as an example. For the operations described above, an illustration and description of time points are omitted. In the present embodiment, the second stack Q of paper sheets corresponds to the last stack of media. 
     After the stapling process is executed on the first stack Q of paper sheets, the discharge of the stack Q of paper sheets is started by the discharge roller  48  at a time point to and terminated at a time point tB. Subsequently, an operation of transporting the next paper sheets P and an operation of aligning the next paper sheets P are executed. However, since a position where the stapling process is executed on the paper sheets P is not changed and thus the moving motor  36  does not operate and does not execute holding. After the stapling process is executed in this state, the discharge of the stack Q of paper sheets is started by the discharge roller  48  at a time point tC and terminated at a time point tD. In this manner, the stapling process is executed once on each of the two stacks of paper sheets Q. 
     Next, actions of the post-processing unit  30  according to the first embodiment are described. The sections of the post-processing unit  30  are described with reference to  FIGS.  1  to  6   , and a description of the individual figure numbers is omitted. 
       FIG.  10    is a flowchart illustrating a procedure for processes from a process of receiving paper sheets P by the controller  22  to a process of discharging a stack Q of the paper sheets after the stapling process. The CPU  24  reads the program PR from the memory  26  and loads and executes the program PR, thereby executing the processes illustrated in  FIG.  10   . 
     In step S 10 , the CPU  24  causes the paddle  46  to operate and transport a plurality of paper sheets P to the processing tray  32 . Then, the process procedure proceeds to step S 12 . 
     In step S 12 , the CPU  24  causes the guide motor  38  to operate and move the side cursors  43  and  44 , thereby causing the side cursors  43  and  44  to align the plurality of paper sheets P. Then, the process procedure proceeds to step S 14 . 
     In step S 14 , the CPU  24  causes the moving motor  36  to operate and move the stapler  60  from an initial position to the position P 4 . Then, the process procedure proceeds to step S 16 . 
     In step S 16 , the CPU  24  determines whether the movement of the stapler  60  in the Y direction has been terminated. As an example, the CPU  24  determines, based on a time period that has elapsed after the start of the movement of the stapler  60 , whether the stapler  60  has reached the position P 4 . When the stapler  60  has reached the position P 4  (Yes in S 16 ), the process procedure proceeds to step S 18 . When the stapler  60  has not reached the position P 4  (No in S 16 ), the process procedure proceeds to step S 14 . 
     In step S 18 , the CPU  24  determines whether the plurality of paper sheets P to be subjected to the stapling process are not the last stack Q of paper sheets. When the plurality of paper sheets P are not the last stack Q of paper sheets (No in S 18 ), the process procedure proceeds to step S 20 . When the plurality of paper sheets P are the last stack Q of paper sheets (Yes in S 18 ), the process procedure proceeds to step S 28 . 
     In step S 20 , the CPU  24  supplies the supply current Ib or the supply voltage Vb to the moving motor  36  to keep the moving motor  36  in such a manner that the moving motor  36  does not rotate. Then, the process procedure proceeds to step S 22 . 
     In step S 22 , the CPU  24  causes the stapling motor  37  to operate to cause the stapler  60  to operate and start the stapling process. Then, the process procedure proceeds to step S 24 . 
     In step S 24 , the CPU  24  stops the operation of the stapling motor  37 , thereby stopping the operation of the stapler  60 . Then, the process procedure proceeds to step S 26 . 
     In step S 26 , the CPU  24  stops the supply of the supply current Ib or the supply voltage Vb to the moving motor  36 . This terminates the keeping of the moving motor  36 . Then, the process procedure proceeds to step S 32 . 
     In step S 28 , the CPU  24  causes the stapling motor  37  to operate to cause the stapler  60  to operate and start the stapling process. Then, the process procedure proceeds to step S 30 . 
     In step S 30 , the CPU  24  stops the operation of the stapling motor  37 , thereby stopping the operation of the stapler  60 . Then, the process procedure proceeds to step S 32 . 
     In step S 32 , the CPU  24  causes the transport motor  23  to operate to cause the discharge roller  48  to rotate and discharge the stack Q of paper sheets. Then, the process procedure proceeds to step S 34 . 
     In step S 34 , the CPU  24  determines whether the stapling process on the next paper sheets P is to be executed. As an example, the determination is made based on a difference between a set number of stacks Q of paper sheets and the number of stacks Q of paper sheets discharged. When the stapling process on the next paper sheets P is not to be executed (No in step S 34 ), the program PR is terminated. When the stapling process on the next paper sheets P is to be executed (Yes in step S 34 ), the process procedure proceeds to step S 10 . 
       FIG.  11 A  illustrates a state in which the post-processing unit  30  ( FIG.  1   ) has stapled the first stack Q of paper sheets with a staple  61  at upper left portions of the paper sheets.  FIG.  11 B  illustrates a state in which the post-processing unit  30  ( FIG.  1   ) has stapled the fortieth stack Q of paper sheets with a staple  61  at upper left portions of the paper sheets.  FIG.  11 C  illustrates a state in which the post-processing unit  30  ( FIG.  1   ) has stapled the eightieth stack Q of paper sheets with a staple  61  at upper left portions of the paper sheets. The staples  61  indicated by solid lines are used to staple the paper sheets by the post-processing unit  30 , while staples  61  indicated by broken lines are used to staple the paper sheets by a device according to a comparative example in which a moving motor  36  is not kept based on a supply current Ib or a supply voltage Vb. 
     In the device according to the comparative example, as stapling is progressed in order from the first stack of paper sheets through the fortieth stack of paper sheets to the eightieth stack of paper sheets, a deviation of the position of a staple  61  from a dashed-and-dotted line G indicating a predetermined stapling position becomes larger. 
     On the other hand, in the post-processing unit  30  according to the present embodiment, even when stapling is progressed in order from the first stack of paper sheets through the fortieth stack of paper sheets to the eightieth stack of paper sheets, a deviation of the position of a staple  61  from a predetermined stapling position is smaller than that in the comparative example. 
     As described above, according to the post-processing unit  30 , the set current Ia and the supply current Ib are the same or the set voltage Va and the supply voltage Vb are the same in the first control and the second control, and thus a converter that changes the magnitude of output of the supply current Ib or the supply voltage Vb to be supplied to the driving section  34  is not required. For example, a DC-DC converter is not required. Therefore, the configuration of the post-processing unit  30  can be simplified. 
     In addition, since the supply current Ib or the supply voltage Vb that has the same value as the set current Ia or the set voltage Va is supplied to the driving section  34 , the stapling process is executed by the stapler  60  in a state in which force to hold the position of the stapler  60  is increased. Therefore, even when a component of impact force caused by the operation of executing the stapling process acts on the stapler  60 , it is possible to suppress a deviation of the position of the stapler  60  in the Y direction. 
     In the method for controlling the post-processing unit  30  and the program PR of the post-processing unit  30 , the same actions and effects as those of the post-processing unit  30  can be obtained. 
     According to the post-processing unit  30 , the first control is not executed in the stapling process executed a plurality of times and thus it is possible to increase a speed at which the stapling process is executed, compared to a configuration in which the first control is executed every time the stapling process is to be executed. 
     According to the post-processing unit  30 , the operation of the stapler  60  to execute the stapling process is synchronized with the operation of the driving section  34 , and an extra supply current Ib or an extra supply voltage Vb is hardly supplied, compared to a configuration in which the foregoing operations are not synchronized. Therefore, it is possible to reduce power to be consumed by the post-processing unit  30 . 
     When a time period required to align a plurality of paper sheets P changes, the start time t 10  ( FIG.  8   ) of the stapling process changes from the time point set in advance. Specifically, the time point t 4  ( FIG.  8   ) when the alignment is terminated may deviate to a time point before or after the set time point depending on a mounted state of a plurality of paper sheets P and the time point t 10  may deviate from the set time point to a time point before or after the set time point due to the deviation of the time point t 4 . As described above, in the post-processing unit  30  according to the first embodiment, the operation of executing the stapling process is synchronized with the operation of the driving section  34 . Therefore, even when the time point t 4  when the alignment is terminated deviates to a time point before or after the set time point, an extra supply current Ib or an extra supply voltage Vb is hardly supplied and it is possible to reduce power to be consumed by the post-processing unit  30 . 
     According to the post-processing unit  30 , the moving motor  36  starts the holding at the time point t 9  before the time point t 10  when the operation of executing the stapling process is started, and force to hold the stapler  60  by the moving motor  36  is increased. Therefore, when the stapling process is executed by the stapler  60 , it is possible to suppress a deviation of the position of the stapler  60  in the Y direction. 
     According to the post-processing unit  30 , when the set time period Δt elapses after the time point t 9  that is the start time of the supply of the supply current Ib or the supply voltage Vb to the moving motor  36  of the driving section  34 , the supply of the current or the voltage to the driving section  34  from the power supply  16  is stopped. Therefore, it is possible to further reduce power to be consumed by the post-processing unit  30 , compared to a configuration in which the current or the voltage is supplied to the driving section  34  for a time period longer than the set time period Δt. 
     According to the post-processing unit  30 , when the set elapsed time period Δt 1  elapses after the end time t 11  of the operation of the stapler  60  to execute the stapling process, the supply of the current or the voltage to the moving motor  36  of the driving section  34  from the power supply  16  is stopped. Therefore, it is possible to further reduce power to be consumed by the post-processing unit  30 , compared to a configuration in which the current or the voltage is supplied to the driving section  34  for a time period longer than the set elapsed time period Δt 1 . 
     According to the post-processing unit  30 , the holding of the position of the stapler  60  is released after the termination of the operation of the stapler  60 . Therefore, it is possible to suppress a deviation of the position of the stapler  60  in the Y direction, while reducing power to be consumed by the post-processing unit  30 . 
     Since the stapling process is not executed after the last stapling process, a problem does not occur even when the position of the stapler  60  deviates in the Y direction. According to the post-processing unit  30 , since the number of times that the second control is executed is reduced by 1, it is possible to reduce power to be consumed by the post-processing unit  30 , compared to a configuration in which the second control is executed every time the stapling process that is executed a plurality of times is to be executed. 
     When the number of times that the stapling process is executed on one portion of a paper sheet P is 1, no stapling process is executed after the stapling process executed once. Therefore, a problem does not occur even when the position of the stapler  60  deviates in the Y direction. In this case, the second control is not executed and thus it is possible to reduce power to be consumed by the post-processing unit  30 , compared to a configuration in which the second control is executed when the stapling process is to be executed once. 
     According to the post-processing unit  30 , since force that acts on the stapler  60  in the Y direction increases, it is possible to easily move the stapler  60  in the Y direction as a result. 
     Second Embodiment 
     Next, an example of a post-processing device, a method for controlling the post-processing device, and a program for controlling the post-processing device according to a second embodiment of the present disclosure is described in detail. Sections that are common to the first embodiment are indicated by the same reference signs as those described in the first embodiment, and a description thereof and a description of the individual figure numbers are omitted. 
     A post-processing unit  30  according to the second embodiment is different from the post-processing unit  30  according to the first embodiment in that a stapler  60  executes a stapling process at two positions P 2  and P 3 . The position P 2  is an example of a first position. The position P 3  is an example of a second position. 
     In the post-processing unit  30  illustrated in  FIG.  6   , when the stapling process is executed a plurality of times at the position P 2  and the position P 3  different from the position P 2  on a paper sheet P in the Y direction, the controller  22  ( FIG.  3   ) executes the third control at the positions P 2  and P 3 . 
     Specifically, as illustrated in  FIG.  12   , a stack Q of paper sheets is stapled with two staples  61  at end portions of the stack Q of paper sheets in the positive A direction in such a manner that the two staples  61  are arranged at an interval in the Y direction. 
       FIG.  13    is a timing chart illustrating the case where an operation of transporting paper sheets P, an operation of aligning the paper sheets P, an operation of the moving motor  36 , and an operation of the stapler  60  to execute the stapling process are executed on one stack Q of the paper sheets as an example of an operation of the post-processing unit  30  according to the second embodiment. In an actual operation, each of the operations illustrated in  FIG.  13    is executed a plurality of times on a plurality of stacks Q of paper sheets. For the operations described above, an illustration and description of time points are omitted. 
     In the second embodiment, a time point t 8  when the stapler  60  is stopped moving is set as an example of a reference time point. 
     After the first stapling process is executed at the position P 2  ( FIG.  6   ) before a time point t 12 , the set current Ia or the set voltage Va is supplied to the moving motor  36  at a time point t 13  and the stapler  60  starts moving at a time point t 14 . The supply of the set current Ia or the set voltage Va to the moving motor  36  is stopped at a time point t 15  and the stapler  60  is stopped moving at a time point t 16 . Therefore, the stapler  60  reaches the position P 3  ( FIG.  6   ). 
     The operation of the stapler  60  to execute the stapling process is started at a time point t 17  and terminated at a time point t 18 . 
     Subsequently, the discharge of the stack Q of paper sheets is started by the discharge roller  48  ( FIG.  1   ) at a time point to and terminated at a time point tB. In this manner, the stapling process is executed twice on one stack Q of paper sheets. After that, the stapling process is executed on the second and subsequent stacks Q of paper sheets in the same manner as described above. 
     Next, actions of the post-processing unit  30  according to the second embodiment are described. Sections of the post-processing unit  30  are described with reference to  FIGS.  1  to  6   , and a description of the individual figure numbers is omitted. 
       FIG.  14    is a flowchart illustrating a procedure for processes from a process of receiving paper sheets P by the controller  22  to a process of discharging a stack Q of the paper sheets after the stapling process. The CPU  24  reads the program PR from the memory  26  and loads and executes the program PR, thereby executing the processes illustrated in  FIG.  14   . 
     In step S 50 , the CPU  24  causes the paddle  46  to operate and transport a plurality of paper sheets P to the processing tray  32 . Then, the process procedure proceeds to step S 52 . 
     In step S 52 , the CPU  24  causes the guide motor  38  to operate and move the side cursors  43  and  44 , thereby causing the side cursors  43  and  44  to align the plurality of paper sheets P. Then, the process procedure proceeds to step S 54 . 
     In step S 54 , the CPU  24  causes the moving motor  36  to operate and move the stapler  60  from an initial position to the position P 2 . The stapler  60  may stand by at the position P 2  from an initial state. Then, the process procedure proceeds to step S 56 . 
     In step S 56 , the CPU  24  determines whether the movement of the stapler  60  in the Y direction has been terminated. When the stapler  60  has reached the position P 2  (Yes in S 56 ), the process procedure proceeds to step S 58 . When the stapler  60  has not reached the position P 2  (No in step S 56 ), the process procedure proceeds to step S 54 . 
     In step S 58 , the CPU  24  supplies the supply current Ib or the supply voltage Vb to the moving motor  36  to keep the moving motor  36  in such a manner that the moving motor  36  does not rotate. Then, the process procedure proceeds to step S 60 . 
     In step S 60 , the CPU  24  causes the stapling motor  37  to operate to cause the stapler  60  to operate and start the stapling process. Then, the process procedure proceeds to step S 62 . 
     In step S 62 , the CPU  24  stops the operation of the stapling motor  37 , thereby stopping the operation of the stapler  60 . Then, the process procedure proceeds to step S 64 . 
     In step S 64 , the CPU  24  stops the supply of the supply current Ib or the supply voltage Vb to the moving motor  36 . This terminates the keeping of the moving motor  36 . Then, the process procedure proceeds to step S 66 . 
     In step S 66 , the CPU  24  causes the moving motor  36  to operate and move the stapler  60  from the position P 2  to the position P 3 . Then, the process procedure proceeds to step S 68 . 
     In step S 68 , the CPU  24  determines whether the movement of the stapler  60  in the Y direction has been terminated. When the stapler  60  has reached the position P 3  (Yes in step S 68 ), the process procedure proceeds to step S 70 . When the stapler  60  has not reached the position P 3  (No in step S 68 ), the process procedure proceeds to step S 66 . 
     In step S 70 , the CPU  24  causes the stapling motor  37  to operate to cause the stapler  60  to operate and start the stapling process. Then, the process procedure proceeds to step S 72 . 
     In step S 72 , the CPU  24  stops the operation of the stapling motor  37 , thereby stopping the operation of the stapler  60 . Then, the process procedure proceeds to step S 74 . 
     In step S 74 , the CPU  24  causes the transport motor  23  to operate and rotate the discharge roller  48 , thereby causing the discharge roller  48  to discharge the stack Q of paper sheets. Then, the process procedure proceeds to step S 76 . 
     In step S 76 , the CPU  24  determines whether the stapling process on the next paper sheets P is to be executed. As an example, the determination is made based on a difference between a set number of stacks Q of paper sheets and the number of stacks Q of paper sheets discharged. When the stapling process on the next paper sheets P is not to be executed (No in S 76 ), the CPU  24  terminates the program PR. When the stapling process on the next paper sheets P is to be executed (Yes in step S 76 ), the process procedure proceeds to step S 50 . 
     According to the post-processing unit  30  according to the second embodiment, the supply of the supply current Ib or the supply voltage Vb to the moving motor  36  of the driving section  34  is stopped when the stapler  60  is at the position P 2  or P 3 . Therefore, it is possible to reduce power to be consumed by the post-processing unit  30 , compared to a configuration in which the supply current Ib or the supply voltage Vb is continuously supplied to the driving section  34 . 
     Although the recording systems  1  and the post-processing units  30  according to the first and second embodiments of the present disclosure basically have the foregoing configurations, a partial configuration may be modified, omitted, or the like without departing from the gist of the present disclosure. Modifications are described below. 
     In each of the post-processing units  30  according to the first and second embodiments, the controller  22  may not synchronize the operation of the stapler  60  to execute the stapling process with the operation of the driving section  34  using, as a reference time point, a time point when a signal is input before the start of the operation of the stapler  60  to execute the stapling process. 
     When the set time period elapses after the start time of the operation of the stapler  60  to execute the stapling process, the controller  22  may not stop the supply of the current or the voltage to the driving section  34 . For example, when a predetermined time period elapses after the start time of a movement of the stapler  60 , the controller  22  may stop the supply of the current or the voltage to the driving section  34 . 
     When the set elapsed time period elapses after the end time of the operation of the stapler  60  to execute the stapling process, the controller  22  may not stop the supply of the current or the voltage to the driving section  34 . For example, the end time of the operation of executing the stapling process may be the same as the time when the supply of the current or the voltage to the driving section  34  is stopped. 
     The first time period Δt 1  may be the same as the second time period Δt 2  or may be shorter than the second time period Δt 2 . The first time period Δt 1  may be 0 and second time period Δt 2  may be 0. The start time of the holding operation of the moving motor  36  may be after the start time of the operation of executing the stapling process as long as it is possible to reduce power to be consumed by the post-processing unit  30  and suppress a deviation of the position of the stapler  60  in the Y direction. Similarly, the end time of the holding operation of the moving motor  36  may be before the end time of the operation of executing the stapling process as long as it is possible to reduce power to be consumed by the post-processing unit  30  and suppress a deviation of the position of the stapler  60  in the Y direction. 
     The controller  22  may execute the second control in the last stapling process. Even when the number of times that the stapling process is executed on one portion of a paper sheet P is 1, the controller  22  may execute the second control. 
     Force that acts on the stapler  60  in the Y direction when the stapler  60  staples a paper sheet P may be equal to holding force caused by detent torque when the coil  36 A is not excited. 
     A time point when the holding by the moving motor  36  is terminated may be the same as the end time of the stapling process by the stapler  60 . A convergence time point when vibration of the stapler  60  converges after the stop of the stapling process may be checked in advance, and a time point when the holding by the moving motor  36  is terminated and the convergence time point may be set to the same time point. 
     As a reference time point when the holding by the moving motor  36  and the stapling process by the stapler  60  are synchronized, a time point when a paper sheet P is received may not be used. The start time or end time of a movement of the stapler  60  may be used as the reference time point. 
     In a time period for which the stapler  60  is not moved, the supply current Ib or the supply voltage Vb may be continuously supplied to the moving motor  36 . 
     As an example of post-processing other than the stapling process, a process of pressing a plurality of paper sheets P to bond the paper sheets P together may be executed or a process of forming a through-hole extending through a plurality of paper sheets P in a thickness direction of the plurality of paper sheets P may be executed. 
     The supply of the supply current Ib or the supply of the supply voltage Vb may be selected. To control the moving motor  36 , constant current control is preferably executed. However, to control the moving motor  36 , constant voltage control may be executed. 
     The CPU  24  may not move the stapler  60  from the initial position after the alignment of a plurality of paper sheets P by the side cursors  43  and  44 . For example, the CPU  24  may move the stapler  60  from the initial position at the same time as the alignment by the side cursors  43  and  44 . Alternatively, the CPU  24  may move the stapler  60  from the initial position in the transport of a paper sheet P to the processing tray  32 . Furthermore, the CPU  24  may move the stapler  60  from the initial position before the transport of a paper sheet P to the processing tray  32 . Due to these operations, it is possible to shorten a time period required until the post-processing is terminated. 
     In the post-processing unit  30  according to the first embodiment, a position where the stapling process is executed on paper sheets P may not be limited to the position P 4  where upper right portions of the paper sheets P.A position where the stapling process is executed on paper sheets P may be the position P 1  where upper left portions of the paper sheets P. 
     In the post-processing unit  30  according to the second embodiment, the stapling process may be executed on other paper sheets P at the positions P 2  and P 3  and may be executed twice on a plurality of stacks Q of paper sheets. In addition, positions where the stapling process is executed on paper sheets P may not be limited to the two positions P 2  and P 3  and may be three or more positions. Furthermore, the end time of the stapling process and the end time of the holding by the moving motor  36  may be synchronized using the end time of the stapling process as a reference time point. 
     The medium may not be limited to a paper sheet P and may be a film, cloth, or the like. 
     The stapling process to be executed on paper sheets P is not limited to the process to be executed on a plurality of planar paper sheets P stacked in the B direction and may be a stapling process to be executed on a plurality of paper sheets P folded in advance and stacked in the B direction. 
     The stapling process may not be executed to staple paper sheets P with staples in such a manner that the staples are arranged along longer sides of the paper sheets P. The stapling process may be executed to staple paper sheets P with staples in such a manner that the staples are arranged along shorter sides of the paper sheets P.