Patent Publication Number: US-10308466-B2

Title: Post-processing apparatus including a pushing member

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is based on and claims priority under 35 USC 119 from Japanese Patent Application No. 2017-049828 filed Mar. 15, 2017. 
     BACKGROUND 
     (i) Technical Field 
     The present invention relates to a post-processing apparatus. 
     (ii) Related Art 
     In a post-processing apparatus that performs post-processing, such as stapling or punching, on a recording medium, such as a printing sheet, on which a printing operation has been performed, plural printing sheets on each of which the post-processing is to be performed are stored in a storing unit called a compilation tray, and then the post-processing is performed on the stored printing sheets. 
     When plural printing sheets are accommodated in a compilation tray, and post-processing, such as stapling, is performed, the vertical positions of the trailing ends of the printing sheets may sometimes not become lower depending on the type (weight) of the printing sheets, and as a result, the printing sheets may sometimes not be accommodated in the compilation tray. 
     SUMMARY 
     According to an aspect of the invention, there is provided a post-processing apparatus including a storing unit that stores plural recording media for performing post-processing, a pushing member that pushes trailing ends of the recording media stored in the storing unit toward an ejection port, and a controller that controls the pushing member to stop at a position at which the pushing member supports a recording medium that is transported. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       An exemplary embodiment of the present invention will be described in detail based on the following figures, wherein: 
         FIG. 1  is a perspective view illustrating the appearance of a post-processing apparatus according to an exemplary embodiment of the present invention; 
         FIG. 2  is a diagram illustrating a state in which the post-processing apparatus according to the exemplary embodiment of the present invention is used by being connected to a printer; 
         FIG. 3  is a schematic sectional view illustrating the configuration of a principal mechanism for performing post-processing in the post-processing apparatus according to the exemplary embodiment of the present invention; 
         FIG. 4  is a perspective view illustrating a peripheral portion of stoppers in the post-processing apparatus according to the exemplary embodiment of the present invention; 
         FIG. 5  is a diagram illustrating the state of the stoppers mounted on one of ejection belts in the configuration illustrated in  FIG. 4 ; 
         FIG. 6  is a block diagram illustrating a control configuration of the post-processing apparatus according to the exemplary embodiment of the present invention; 
         FIG. 7  is a diagram illustrating operation of the post-processing apparatus according to the exemplary embodiment of the present invention; 
         FIG. 8  is a diagram illustrating operation of the post-processing apparatus according to the exemplary embodiment of the present invention; 
         FIG. 9  is a diagram illustrating operation of the post-processing apparatus according to the exemplary embodiment of the present invention; 
         FIG. 10  is a diagram illustrating operation of the post-processing apparatus according to the exemplary embodiment of the present invention; 
         FIG. 11  is a diagram illustrating operation of the post-processing apparatus according to the exemplary embodiment of the present invention; 
         FIG. 12  is a diagram illustrating operation of the post-processing apparatus according to the exemplary embodiment of the present invention; 
         FIG. 13  is a diagram illustrating operation of the post-processing apparatus according to the exemplary embodiment of the present invention; 
         FIG. 14  is a diagram illustrating operation of the post-processing apparatus according to the exemplary embodiment of the present invention; 
         FIG. 15  is a diagram illustrating operation of the post-processing apparatus according to the exemplary embodiment of the present invention; 
         FIG. 16  is a diagram illustrating operation of the post-processing apparatus according to the exemplary embodiment of the present invention; 
         FIG. 17  is a diagram illustrating operation of a post-processing apparatus according to a comparative example; 
         FIG. 18  is a diagram illustrating operation of the post-processing apparatus according to the comparative example; 
         FIG. 19  is a flowchart illustrating operation of the post-processing apparatus according to the exemplary embodiment of the present invention; 
         FIG. 20  is a flowchart illustrating operation of the post-processing apparatus according to the exemplary embodiment of the present invention; 
         FIG. 21A  is a perspective view illustrating a standby position of one of the stoppers when a normal sheet is subjected to processing, and  FIG. 21B  is a perspective view illustrating a standby position of the one of the stoppers when a thick sheet is subjected to processing; and 
         FIG. 22A  is a schematic sectional view illustrating standby positions of the stoppers when a normal sheet is subjected to processing, and  FIG. 22B  is a schematic sectional view illustrating standby positions of the stoppers when a thick sheet is subjected to processing. 
     
    
    
     DETAILED DESCRIPTION 
     An exemplary embodiment of the present invention will be described in detail below with reference to the drawings. 
       FIG. 1  is a perspective view illustrating the appearance of a post-processing apparatus  10  according to an exemplary embodiment of the present invention. 
     As illustrated in  FIG. 1 , the post-processing apparatus  10  according to the exemplary embodiment of the present invention has a shape such that the post-processing apparatus  10  is used by being connected to a printer, which functions as an image forming apparatus. The post-processing apparatus  10  has a function of performing post-processing, such as stapling, on plural printing sheets that are recording media ejected from the printer and then ejecting a stack of the printing sheets, on which the post-processing has been performed, to an ejection tray  30 . 
       FIG. 2  illustrates a state in which the post-processing apparatus  10  is used by being connected to a printer  90 . 
       FIG. 2  illustrates a state in which the post-processing apparatus  10  ejects, to the ejection tray  30 , a stack of printing sheets obtained by performing the post-processing, such as stapling, on printing sheets that are ejected from the printer  90  and introduced into the post-processing apparatus  10 . 
     The configuration of the post-processing apparatus  10  according to the present exemplary embodiment for performing the post-processing on printing sheets and an ejecting operation that is to be performed after the post-processing has been performed will now be described. 
       FIG. 3  is a schematic sectional view illustrating the configuration of a principal mechanism for performing post-processing in the post-processing apparatus  10  according to the present exemplary embodiment. Note that  FIG. 3  is a schematic sectional view illustrating an operation for ejecting a stack of printing sheets performed by the post-processing apparatus  10  and does not accurately illustrate the positional relationship in the actual configuration. 
     Referring to  FIG. 3 , the post-processing apparatus  10  according to the present exemplary embodiment includes transport rollers  21 , sub-paddles  22 , main paddles  23 , an end guide  24 , a compilation tray  25 , an ejection port  26 , ejection belts  27 , stoppers  28 , rotating rollers  29 , and the ejection tray  30 . 
     The transport rollers  21  transport printing sheets that are ejected from a printer or the like and on which post-processing is to be performed. 
     The compilation tray  25  is a storing unit that stores plural printing sheets for performing post-processing. A post-processing mechanism (not illustrated) performs post-processing such as, for example, stapling or punching on a stack of printing sheets stored in the compilation tray  25 . 
     The main paddles  23  and the sub-paddles  22  are each formed so as to have the shape of a paddle (blade) having flexibility and are transport members that rotate to transport a printing sheet in a given direction. 
     The sub-paddles  22  transport a printing sheet transported from the upstream side of a transport path by the transport rollers  21  in a direction toward the compilation tray  25 . More specifically, the sub-paddles  22  rotate while being in contact with a surface of a printing sheet to transport the printing sheet to the compilation tray  25 . 
     The main paddles  23  keep transporting a printing sheet transported by the sub-paddles  22  further toward the compilation tray  25  until an end of the printing sheet reaches the end guide  24 . 
     The end guide  24  is a sheet-aligning unit used for aligning the trailing end of a stack of printing sheets accommodated in the compilation tray  25 . 
     A tamper (not illustrated) operates in accordance with the timing at which printing sheets reach the end guide  24 , and as a result, alignment of a stack of the printing sheets on the compilation tray  25  in a width direction of the printing sheets is performed. 
     Each of the ejection belts  27  is an endless belt member and is stretched between a corresponding two of the rotating rollers  29 . 
     Each of the stoppers  28  is a hook member that latches onto the trailing end of a stack of printing sheets. In addition, each of the stoppers  28  functions as a support member that supports a lower surface of a leading end portion of a printing sheet from below. A pair of the stoppers  28  are mounted on each of the ejection belts  27 . 
     The ejection belts  27  are driven when ejecting a stack of printing sheets on which the post-processing has been performed. As a result of each of the ejection belts  27  being driven, the corresponding two stoppers  28  move while rotating by 180 degrees for each movement. Then, the stoppers  28  perform an operation for ejecting the stack of printing sheets, on which the post-processing has been performed in the compilation tray  25 , from the ejection port  26  by latching onto (hooking onto) and pushing the trailing end of the stack of the printing sheets. The ejection belts  27  and the stoppers  28  function as pushing members that hook onto and push the trailing ends of the printing sheets stored in the compilation tray  25  toward the ejection port  26 . The ejection belts  27  are driven in such a manner that stop positions of the stoppers  28  vary with the type of printing sheets on which the post-processing is to be performed. Details of performing control in such a manner that the stop positions of the stoppers  28  vary with the type of printing sheets will be described later. In the following description, the positions of the stoppers  28  that are illustrated in  FIG. 3  will hereinafter be referred to as home positions. Here, the home positions refer to positions at which the stoppers  28  are accommodated in a body of the post-processing apparatus  10 . 
       FIG. 4  illustrates the peripheral structure of the stoppers  28  in the post-processing apparatus  10  according to the present exemplary embodiment. 
       FIG. 4  illustrates the two ejection belts  27  on which a corresponding two of the stoppers  28  are mounted. 
     Referring to  FIG. 4 , the rotating rollers  29 , each of which is located on one end side of a corresponding one of the two ejection belts  27 , are each driven by a motor (not illustrated) serving as a driving source for driving the corresponding ejection belt  27  so that the ejection belt  27  rotates. When the motors rotate, the rotating rollers  29  are driven, and the two ejection belts  27  rotate at the same time such that the stoppers  28  move in parallel with each other. 
       FIG. 5  is illustrates a state in which two of the stoppers  28  are mounted on the corresponding ejection belt  27  in the configuration illustrated in  FIG. 4 . 
     A hook  32  is formed on a surface of each of the stoppers  28 , the surface facing a direction of movement of the stopper  28 . An inclined portion  38  is formed on a surface of each of the stoppers  28 , the surface facing a direction opposite to the direction of movement of the stopper  28 . 
     Each of the hooks  32  is formed at an end portion of the corresponding stopper  28  so as to project in the direction of movement of the stopper  28 . 
     Each of the inclined portions  38  is formed in a side surface of the corresponding stopper  28 , the side surface being opposite to a surface of the stopper  28  on which the corresponding hook  32  is formed. In a state where the stoppers  28  are mounted on the ejection belt  27 , each of the inclined portions  38  is formed so as to be inclined from the side on which the ejection belt  27  is present toward the side on which the corresponding hook  32  is present in the direction of movement of the stopper  28 . 
     In other words, each of the stoppers  28  is configured to latch onto the trailing end of a stack of printing sheets on the compilation tray  25  by using the hooks  32  and push the stack of printing sheets toward the ejection port  26 . Each of the stoppers  28  is configured to support the leading end of a printing sheet, which is to be transported to the compilation tray  25 , from the side on which the inclined portion  38  thereof is present in accordance with the type (thickness) of the printing sheet, and the trailing end of the printing sheet supported by the stopper  28  falls onto the compilation tray  25  and is drawn in by the main paddles  23  so as to be further transported toward the compilation tray  25 . 
     Each of the stoppers  28  according to the present exemplary embodiment is detachable from the corresponding ejection belt  27 , and when the stopper  28  is required to be replaced due to, for example, deterioration thereof, the stopper  28  may be easily replaced. In addition, each of the stoppers  28  is capable of being mounted on a versatile belt member. 
     Each of the ejection belts  27  is formed of, for example, an elastic member made of an elastic rubber or the like, which is a material such as ethylene propylene diene monomer (EPDM) rubber having a high elastic limit and a low modulus of elasticity. Each of the stoppers  28  is formed of, for example, a member made of a resin. 
       FIG. 6  is a block diagram illustrating a control configuration of the post-processing apparatus  10 . 
     As illustrated in  FIG. 6 , the above-mentioned printer  90 , a central processing unit (CPU)  92 , a memory  94 , a storage device  96 , and a user interface (UI) device  98  are connected to the post-processing apparatus  10  via a bus. 
     The transport rollers  21 , the sub-paddles  22 , the main paddles  23 , the rotating rollers  29 , the post-processing mechanism, and the like are controlled among the components included in the post-processing apparatus  10 . 
     The CPU  92  controls the operation of the post-processing apparatus  10  and the operation of the printer  90  by running programs written in the memory  94  or the storage device  96 . An input received via the UI device  98  is transmitted to the CPU  92 , and display information is transmitted from the CPU  92  to the UI device  98 . 
     Note that the CPU  92  may run programs stored in a transportable storage medium, such as a compact disc read-only memory (CD-ROM), which is not illustrated, or may run programs provided via a communication device, which is not illustrated. 
     The storage device  96  stores information related to the type of a recording medium such as the basis weight (thickness (weight)) of a sheet. For example, a hard disk drive or the like is used as the storage device  96 , and the storage device  96  stores data in a writable and readable manner. 
     The operation of the post-processing apparatus  10  according to the present exemplary embodiment will now be described with reference to  FIG. 7  to  FIG. 16 .  FIG. 7  to  FIG. 16  are diagrams each illustrating an operation for performing the post-processing on a printing sheet P, which is a thick sheet, by using the post-processing apparatus  10  according to the present exemplary embodiment. Here, the thick sheet refers to a sheet having a basis weight of, for example, 150 g/m 2  or greater. Note that the basis weight of a normal sheet is about 64 g/m 2  to about 68 g/m 2 . 
     First, in an initial state, blades of the sub-paddles  22  are stationary at positions at which the blades face away from a sheet transport path as illustrated in  FIG. 7 . 
     Thus, as illustrated in  FIG. 7 , the printing sheet P transported by the transport rollers  21  passes under the sub-paddles  22  without being hindered and then stops. 
     In this case, two of the stoppers  28  are stationary at positions in the vicinity of a highest portion of the compilation tray  25  and support a lower surface of a leading end portion of the printing sheet P. Thus, as illustrated in  FIG. 8 , the trailing end of the printing sheet P falls onto the compilation tray  25 . 
     In the state illustrated in  FIG. 8 , when power is supplied to the motors so as to cause the sub-paddles  22  to start rotating, as illustrated in  FIG. 9 , the sub-paddles  22  are brought into contact with the printing sheet P, and the printing sheet P is transported. Then, as illustrated in  FIG. 10 , the printing sheet P is brought into contact with the main paddles  23  and transported until the printing sheet P abuts against the end guide  24 . 
     Subsequently, when the next printing sheet P is transported by the transport rollers  21 , an operation similar to the above is performed, and a predetermined number of printing sheets P are accommodated in the compilation tray  25  as illustrated in  FIG. 11 . After the printing sheets P have been accommodated in the compilation tray  25 , each of the motors is brought into a non-operating state, and each of the sub-paddles  22  is caused, by a spring, to stop at a stop position at which the sub-paddle  22  does not hinder the passage of the printing sheets P. 
     After the post-processing has been performed on the stack of printing sheets P, as illustrated in  FIG. 12 , each of the ejection belts  27  is driven by the driving source (not illustrated). Then, as illustrated in  FIG. 13 , the hooks  32  of the stoppers  28  latch onto and push the trailing end of the stack of printing sheets P, on which the post-processing has been performed, and the stoppers  28  stop at the positions in the vicinity of the highest portion of the compilation tray  25  as illustrated in  FIG. 14 . The stack of printing sheets P, on which the post-processing has been performed, is ejected from the ejection port  26 . As a result, as illustrated in  FIG. 15 , the stack of the printing sheets P, which has been ejected, falls onto the ejection tray  30 . 
     By performing control such as that described above, a stack of printing sheets obtained by performing the post-processing on plural printing sheets, on each of which a printing operation has been performed, is ejected to the ejection tray  30 . When processing based on a single execution instruction is complete, the stoppers  28  move to their home positions and stop as illustrated in  FIG. 16 . 
     Here, different types of printing sheets have different thicknesses. When a thick sheet, a highly resilient sheet, a downwardly curled sheet, or the like (hereinafter referred to as a thick sheet or the like) is used as a printing sheet, there is a case where the vertical position of the leading end of the printing sheet becomes lower while the vertical position of the trailing end of the printing sheet does not, and as a result, the printing sheet will not be accommodated in the compilation tray  25 . 
       FIG. 17  is a diagram illustrating a state in which a thick sheet is transported while the stop positions of the stoppers  28  are located at the home positions, and  FIG. 18  is a diagram illustrating a state in which a thick sheet is transported while the stop positions of the stoppers  28  are located at the home positions and in which the angle of the ejection tray  30  has been changed. 
     As illustrated in  FIG. 17 , especially when transporting a printing sheet such as a thick sheet or the like toward the compilation tray  25  that is short in length in a transport direction, there is a case where the vertical position of the leading end of the printing sheet becomes lower while the vertical position of the trailing end of the printing sheet becomes higher, and as a result, the printing sheet will not be transported toward the compilation tray  25  as a result of rotation of the main paddles  23 . 
     In order to prevent the vertical position of the leading end of a printing sheet, such as a thick sheet or the like, from becoming lower, if the angle of the ejection tray  30  is increased as illustrated in  FIG. 18 , there is a possibility that the printing sheet that is subsequently transported will displace printing sheets on the ejection tray  30  by pushing against them, which in turn leads to a sheet alignment failure on the ejection tray  30 . 
     When the friction coefficient of rubber included in the paddles is decreased due to physical properties of sheets and wear and tear of the paddles, the force that draws in a sheet is also decreased. If the transport force of the paddles is too large, there is a possibility that a secondary problem such as buckling will occur. Regarding physical properties of the sheets, in the case of a coated sheet, a copy sheet, or the like, a calcium carbonate component adheres to the paddles and causes a decrease in the friction coefficient of the rubber included in the paddles. Since a thick sheet or the like is heavy, a sheet-aligning operation may be mechanistically performed with a small transport force on the compilation tray  25  rather than increasing a sheet transport force. 
     Accordingly, in the post-processing apparatus  10  according to the present exemplary embodiment, control is performed such that the trailing ends of printing sheets to be accommodated in the compilation tray  25  are stabilized so as to be easily aligned by lifting the leading ends of the printing sheets in accordance with the type of the printing sheets such as the thicknesses of the printing sheets, and as a result, a sheet accommodation failure is prevented from occurring in the compilation tray  25 . 
     Exemplary operation of the post-processing apparatus  10  according to the present exemplary embodiment will now be described.  FIG. 19  and  FIG. 20  are flowcharts each illustrating operation of the post-processing apparatus  10  according to the present exemplary embodiment.  FIG. 21A  is a perspective view illustrating the stop position (home position) of one of the stoppers  28  when a normal sheet is subjected to processing, and  FIG. 21B  is a perspective view illustrating the stop position of the stopper  28  when a thick sheet is subjected to processing.  FIG. 22A  is a schematic sectional view illustrating the stop positions (home positions) of two of the stoppers  28  when a normal sheet is subjected to processing, and  FIG. 22B  is a schematic sectional view illustrating the stop positions of the stoppers  28  when a thick sheet is subjected to processing. Note that, when starting the processing, the stoppers  28  are stationary at their home positions. 
     First, the CPU  92  acquires information regarding the thickness of one of the printing sheets P from the storage device  96  (step S 10 ). 
     Next, the CPU  92  determines, on the basis of the acquired information regarding the thickness of the printing sheet P, whether the thickness of the printing sheet P to be transported to the post-processing apparatus  10  is equal to or greater than a predetermined threshold, which is, for example, a basis weight of 150 g/m 2  (step S 11 ). 
     In the case where the CPU  92  determines that the thickness of the printing sheet P is equal to or greater than the predetermined threshold (Yes in step S 11 ), the CPU  92  performs control such that the rotating rollers  29  are driven and that two of the stoppers  28  move to and stop at the positions at which the stoppers  28  support the leading end of the printing sheet P, the positions being located in the vicinity of the highest portion of the compilation tray  25  as illustrated in  FIG. 21B  and  FIG. 22B  (step S 12 ). 
     Then, as illustrated in  FIG. 22B , when the trailing end of the thick sheet falls onto the compilation tray  25 , the CPU  92  drives the sub-paddles  22  and the main paddles  23 . As a result, the thick sheet is transported toward the end guide  24 , and a predetermined number of printing sheets P are accommodated in the compilation tray  25 , after which the post-processing is performed on a stack of the printing sheets P (step S 13 ). 
     Subsequently, the CPU  92  causes the stoppers  28  to move and push the trailing end of the stack of the printing sheets P toward the ejection port  26  and controls the stoppers  28  so as to stop at positions at which the stoppers  28  support the printing sheets P (step S 14 ). 
     Then, the CPU  92  determines whether a series of processes has ended (step S 15 ). If the CPU  92  determines that the series of processes has not ended (No in step S 15 ), the process returns to step S 13 . 
     If the CPU  92  determines that the series of processes has ended (Yes in step S 15 ), the CPU  92  controls the stoppers  28  so as to move to and stop at their home positions (step S 16 ). 
     In the case where the CPU  92  determines that the thickness of the printing sheet P is less than the predetermined threshold (No in step S 11 ), as illustrated in  FIG. 22A , when the trailing end of the normal sheet falls onto the compilation tray  25 , the CPU  92  drives the sub-paddles  22  and the main paddles  23 . As a result, the normal sheet is transported toward the end guide  24 , and a predetermined number of printing sheets P are accommodated in the compilation tray  25 , after which the post-processing is performed on a stack of the printing sheets P (step S 20 ). 
     Subsequently, the CPU  92  causes the stoppers  28  to move and push the trailing end of the stack of the printing sheets P toward the ejection port  26  and controls the stoppers  28  so as to stop at their home positions (step S 21 ). 
     After that, the CPU  92  determines whether a series of processes has ended (step S 22 ). If the CPU  92  determines that the series of processes has not ended (No in step S 22 ), the process returns to step S 20 . If the CPU  92  determines that the series of processes has ended (Yes in step S 22 ), the CPU  92  ends the process. 
     In other words, control is performed such that the trailing end of the printing sheet P falls onto the compilation tray  25  and that the printing sheet P is transported toward the end guide  24  as a result of rotations of the sub-paddles  22  and the main paddles  23  so as to be accommodated in the compilation tray  25  in the state illustrated in  FIG. 22A  when the printing sheet P is a normal sheet and in the state illustrated in  FIG. 22B  when the printing sheet P is a thick sheet. 
     [Modifications] 
     Note that, in the above exemplary embodiment, although a configuration has been described in which the stoppers are controlled so as to move to and stop at positions at which the stoppers support a printing sheet when the thickness of the printing sheet is equal to or greater than a predetermined threshold, the present invention is not limited to this configuration, and the stoppers may be controlled so as to be always stationary at the positions at which the stoppers support a printing sheet during the period when the printing sheet is being transported to the compilation tray regardless of the thickness of the printing sheet. 
     In the above exemplary embodiment, although a case has been described in which the present invention is applied to a post-processing apparatus that is configured to be installed onto a printer, the present invention is not limited to such a post-processing apparatus and may also be applied to post-processing apparatuses each having any structure for performing post-processing on a sheet on which a printing operation is not performed as well as on a sheet on which a printing operation has been performed. 
     In the above exemplary embodiment, although a configuration has been described in which the stoppers are controlled so as to stop at positions at which the stoppers support a sheet that is to be transported next or at their home positions, the present invention is not limited to this configuration. After a sheet has been ejected as a result of being pushed toward the ejection port by the stoppers, the stoppers may be controlled so as to move in a direction opposite to the direction in which the stoppers push the sheet and then stop at the positions at which the stoppers support the sheet that is to be transported next. 
     In addition, in the above exemplary embodiment, although a configuration has been described in which the stoppers are detachable from the corresponding ejection belts, the present invention is not limited to this configuration, and the stoppers and the corresponding ejection belts may be integrally formed into one member. 
     Furthermore, in the above-described exemplary embodiment, although a configuration has been described in which two stoppers are mounted on one ejection belt, the present invention is not limited to this configuration, and each ejection belt may be provided with at least one stopper. 
     The foregoing description of the exemplary embodiment of the present invention has been provided for the purposes of illustration and description. It is not intended to be exhaustive or to limit the invention to the precise forms disclosed. Obviously, many modifications and variations will be apparent to practitioners skilled in the art. The embodiment was chosen and described in order to best explain the principles of the invention and its practical applications, thereby enabling others skilled in the art to understand the invention for various embodiments and with the various modifications as are suited to the particular use contemplated. It is intended that the scope of the invention be defined by the following claims and their equivalents.