Patent Publication Number: US-9409741-B2

Title: Sheet processing device, image forming device provided with the same, and sheet bonding method

Description:
RELATED APPLICATIONS 
     The present application is based on, and claims priority from, Japanese Applications No. JP2013-263878 filed Dec. 20, 2013, No. JP2013-263879 filed Dec. 20, 2013, No. JP2013-263880 filed Dec. 20, 2013, No. JP2013-263881 filed Dec. 20, 2013, and No. JP2014-012190 filed Jan. 27, 2014 the disclosure of which is hereby incorporated by reference herein in its entirety. 
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to a processing device that bonds paper sheets carried out from an image forming device, such as a copying machine or a printer, to form a paper sheet bundle and to a device capable of processing paper sheets successively delivered. 
     2. Description of the Related Art 
     A sheet processing device that aligns paper sheets delivered from an image forming device and staples the paper sheets or folds the paper sheets in a booklet form is widely known. Such a sheet processing device is provided with a plurality of sheet storage means for sheet post-processing. For example, in a first sheet storage means, the paper sheets are stored in a bundle and are then stapled and, in a second sheet storage means, the paper sheets stored in a bundle are subjected to saddle stitching and then folded in a booklet form. In recent years, a binding processor that binds a paper sheet bundle without use of a metallic binding needle (metallic staple) in the sheet bundle binding processing and a sheet processing device that uses the binding processor are being provided. 
     For example, Jpn. Pat. Appln. Laid-Open Publication No. 2011-201698 discloses a device that performs bookbinding without use of a metallic binding staple so as to enhance recyclability and safety of the bound paper sheets. In this device, a folding plate and a folding roller pair apply folding to a paper sheet bundle stored in a stacker for storing a plurality of paper sheets in order. A binding mechanism section binds the paper sheet bundle, without use of the metallic staple, in a position at a predetermined interval from a folding position where the paper sheet bundle is subjected to folding by the folding plate and the folding roller pair. 
     In the binding processing, the binding mechanism section causes deformation in a thickness direction of the paper sheet bundle that has been subjected to folding by the folding plate and the folding roller pair so as to bind the paper sheet bundle. More specifically, upper and lower concave-convex crimping teeth are meshed with each other to cause local deformation in the thickness direction of the paper sheet bundle to make the paper sheets to be engaged with each other (see FIGS. 4 and 5 of Jpn. Pat. Appin. Laid-Open Publication No. 2011-201698). 
     A portion to which the binding mechanism applies binding is set so as to be separated by a predetermined interval from the folding position of the paper sheet bundle (see FIGS. 7 and 11 of Jpn. Pat. Appin. Laid-Open Publication No. 2011-201698). In other words, the folding position and binding position are shifted from each other. 
     On the other hand, U.S. Patent Application Publication No. 2013/0133837 (corresponding to Jpn. Pat. Appin. Laid-Open Publication No. 2013-112527) discloses technology that applies a heat sensitive adhesive to paper sheets for bonding to obtain a paper sheet bundle. In this invention, an application section that applies the adhesive is provided at a sheet processing device entrance which is located on an upstream side relative to a sheet processing section that stores the paper sheets in a sheet conveying direction. The application section applies the adhesive to one surface or both surfaces of the carried paper sheet at a portion to be folded. The resultant paper sheet is conveyed along a comparatively long conveying path to a stacker section for sheet storage by means of several stages of conveying rollers. After conveyance to the stacker section, the adhesive-applied positions of the paper sheets are pressurized by a pressure roller to form a paper sheet bundle. Then, the obtained paper sheet bundle is pushed to a folding roller by a folding blade for folding processing. 
     Further, Japanese Patent No. 5,168,474 discloses a bookbinding device provided with a unit housing section that can alternatively houses one of a needle binding unit that applies a needle binding processing to a paper sheet bundle and a paste binding unit that applies pasting onto the paper sheets and pressure-bonds them to form a paper sheet bundle. To this end, the needle binding unit and paste binding unit are set so as to be detachably attached to the unit housing section. Further, this device includes a folding section that folds the paper sheet bundle bound by one of the above units in two. 
     Further, Japanese Patent No. 5,382,597 discloses a device provided with a paste binding unit that applies pasting onto the paper sheets and pressure-bonds them to form a paper sheet bundle and a needle binding unit that performs a needle binding processing. The device alternatively executes the paste binding and needle binding and then executes folding processing. With this configuration, a booklet can be created by paste binding or needle binding according to the need. 
     In the device that aligns paper sheets carried out from an image forming device or the like for subsequent binding processing and/or folding, when the paper sheet bundle is formed without use of the metallic staple or by bonding the paper sheets, the following problems arise. 
     The invention disclosed in Jpn. Pat. Appin. Laid-Open Publications No. 2011-201698 is configured to bind the paper sheet bundle by deforming the paper sheets themselves. For example, upper and lower concave-convex crimping teeth are meshed with each other to cause local deformation in the thickness direction of the paper sheet bundle to make the paper sheets to be engaged with each other. However, it is necessary to mesh the upper and lower concave-convex crimping teeth with a considerable crimping force in order to make the paper sheets to be engaged with each other. An insufficient crimping force results in insufficient binding, that is, only the crimping force cannot make the binding state stable. When the binding position is made to coincide with the folding position in this crimping system, a deformation force due to curve of the paper sheets acts to affect binding performance. 
     Further, as another binding mechanism, there is known a mechanism including a cut forming section that forms a cut bent in a convex shape on one side of a paper sheet bundle and a binding portion forming section that forms, inside a range surrounded by the convex-shaped cut, a binding portion for binding the paper sheet bundle, wherein the convex-shaped cut is inserted into the binding portion for binding. In this case, a comparatively large cut is formed in the paper sheets themselves, so that damage is given to the paper sheets themselves, and outer appearance is affected. 
     Under such circumstances, as disclosed in U.S. Patent Application Publication No. 2013/0133837 (corresponding to Jpn. Pat. Appin. Laid-Open Publication No. 2013-112527), the binding mechanism that binds the paper sheet bundle using an adhesive without use of the crimping mechanism or without forming large cut in the paper sheets can be considered effective. 
     However, in this mechanism, the paper sheet is conveyed along a comparatively long conveying path to a stacker section for sheet storage by means of several stages of conveying rollers, as described above. That is, the sheet applied with an adhesive at the device entrance is conveyed to the stacker section along the comparatively long conveying path through several conveying rollers, so that a sheet jam may occur due to undesired adhesion of the adhesive to surroundings of the conveying path. 
     Further, the adhesive-applied paper sheets stored in the stacker section for bonding are not necessarily aligned with one another, and the paper sheet may be folded in a mutually misaligned state. In addition, in order to prevent the adhesive from being adhered to the surroundings of the long conveying path, it is necessary to select, as a pressure sensitive tape used as the adhesive, one that does not exhibit adhesive power until it receives a significant pressure. That is, it is necessary to carefully select the adhesive to be used and to use a special pressurizing mechanism. 
     On the other hand, in the device disclosed in Japanese Patent No. 5,168,474, one of the needle binding unit and paste binding unit can be attached to the unit housing section of the device. In this configuration, when the paste binding unit is selected to perform pasting, a paper sheet is carried in the unit with a pasting surface (bonding surface) of a preceding paper sheet being exposed, so that the paper sheets may be bonded to each other at an unintended portion. Further, the paper sheet after the pasting is conveyed to a folding device by a distance two or more times a sheet length, so that the adhesive may be adhered to the device component. 
     In the device disclosed in Japanese Patent No. 5,382,597, the paste binding unit and needle binding unit are arranged side by side in the sheet conveying path. Although the paper sheet is conveyed by a suction feeding mechanism in this device, a paper sheet (second paper sheet) is carried in the unit with a pasting surface (bonding surface) of a preceding paper sheet (first paper sheet) being exposed as in the paste binding unit disclosed in Japanese Patent No. 5,168,474. Therefore, for example, a leading end of the second paper sheet to be carried in may be brought into contact with the adhesive on the first paper sheet, with the result that the paper sheets may be bonded to each other at an unintended portion. Further, also in this device, the paper sheet after the pasting is conveyed to an inside of the device by a distance two or more times a sheet length, so that the adhesive may be adhered to the device component. 
     The present invention has been made in view of the above problems, and an object thereof is to provide a comparatively small sheet processing device capable of forming a paper sheet bundle by bonding the paper sheets using an adhesive to reduce stress to be applied to the paper sheet as compared to a case where the paper sheet bundle is bound with a metallic staple or by deforming the paper sheets themselves, capable of comparatively reducing movement of the paper sheet applied with the adhesive to prevent the adhesive from being adhered to a portion other than the paper sheet in the conveying path or stacker section, and capable of reliably bonding the paper sheets through the adhesive at a predetermined position while suppressing the adhesive from being adhered to an unnecessary portion, an image forming device provided with the sheet processing device, and a sheet bonding method. 
     SUMMARY OF THE INVENTION 
     To solve the above problems, the present invention has the following means. 
     That is, the present invention provides a sheet processing device that applies an adhesive onto a paper sheet for bonding paper sheets. The sheet processing device includes: a carry-in path along which the paper sheet is carried in; a stacker section that stores the paper sheet conveyed along the carry-in path; a regulating member that regulates the paper sheet stored in the stacker section; a moving member that moves the stored paper sheet; a bonding member that applies the adhesive onto the paper sheet at a bonding position; and a retreat path that branches off from the carry-in path, along which at least a part of the paper sheet stored in the stacker section is retreated in a direction opposite to a sheet carry-in direction, wherein the bonding member is disposed at a merging point between the carry-in path and retreat path, an adhesive-applied position of a preceding paper sheet is retreated to the retreat path by the moving member when a next paper sheet is carried into the stacker section, and then the next paper sheet is moved to the bonding position for adhesive application, and the above paper sheet retreat operation and adhesive application operation are repeated to generate a paper sheet bundle. The present invention further provides an image forming device provided with the above sheet processing device and a sheet bonding method. 
     The sheet bonding method includes the steps of: applying the adhesive onto a preceding paper sheet at a bonding position; retreating an adhesive-applied position of the preceding paper sheet to the retreat path; carrying in a next paper sheet to the stacker section; moving the next paper sheet to the bonding position with leading end sides of the preceding and next paper sheets overlapped with each other for adhesive application and sheet bonding. The above steps are repeated to generate a paper sheet bundle. 
     With the above configuration, in the present invention, the next paper sheet is carried in after the adhesive-applied position of the preceding paper sheet is moved to the retreat path, and the retreat and carry-in operations are repeated to thereby generate a paper sheet bundle. 
     Thus, a paper sheet bundle can be generated by bonding the paper sheets using an adhesive, so that it is possible to reduce stress to be applied to the paper sheet as compared to a case where the paper sheet bundle is bound with a metallic staple or by deforming the paper sheets themselves. Further, it is possible to comparatively reduce movement of the paper sheet applied with the adhesive to prevent the adhesive from being adhered to a portion other than the paper sheet, thereby preventing the paper sheets from being bonded to each other at a position other than a predetermined position. As a result, there can be provided a sheet processing device, through small, that can bond the paper sheets at a predetermined position, an image forming device provided with the sheet processing device, and a sheet bonding method. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is an explanatory view illustrating an entire configuration in which an image forming device and a sheet processing device according to the present invention are combined; 
         FIG. 2  is an explanatory view illustrating an entire configuration of the sheet processing device according to the present invention provided with an adhesive application device; 
         FIG. 3  is an explanatory view illustrating a peripheral mechanism of the adhesive application device of  FIG. 2 ; 
         FIG. 4  is a perspective view of the adhesive application device of  FIG. 2 ; 
         FIGS. 5A to 5C  are explanatory views of the adhesive application device of  FIG. 3 , in which  FIG. 5A  is a plan view,  FIG. 5B  illustrates an engagement state between a cam member and a stamper holder, and  FIG. 5C  is an explanatory view of the cam member; 
         FIGS. 6A to 6D  are explanatory views of an adhesive tape stamper for applying an adhesive;  FIG. 6A  is an outer appearance view,  FIG. 6B  is a view illustrating a state where an adhesive tape is wound around a reel,  FIG. 6C  is a view illustrating a gear state before pressing of the adhesive tape stamper,  FIG. 6D  is a view illustrating a gear state upon pressing of the adhesive tape stamper; 
         FIGS. 7A to 7C  are explanatory views illustrating an operation state of a stamper holder supporting the adhesive tape stamper; 
         FIGS. 8A to 8C  are explanatory views, continued from  FIG. 7C , illustrating the operation state of a stamper holder supporting the adhesive tape stamper; 
         FIG. 9  is a perspective view of a sheet side edge aligning member disposed in a stacker section; 
         FIG. 10A  illustrates contact and separation of a pinch roller in a sheet carry-in path with respect to a drive roller, and  FIG. 10B  illustrates a pressure roller configured to press and separate from the paper sheet in the stacker section; 
         FIG. 11A  is an explanatory view of a stopper section moved vertically in the stacker section and a gripper, and  FIG. 11B  is a plan view of the stopper section and gripper; 
         FIGS. 12A and 12B  are sheet flow diagrams for explaining a flow of the paper sheet when the paper sheets are bonded to each other to form a paper sheet bundle, in which  FIG. 12A  illustrates a state where a first paper sheet is carried into the carry-in path, and  FIG. 12B  illustrates a state where a rear end of the first paper sheet passes through a branching point between the carry-in path and retreat path; 
         FIGS. 13A and 13B  are sheet flow diagrams continued from  FIG. 12B , in which  FIG. 13A  illustrates a state where the first paper sheet is moved to a bonding position with the rear end of the first paper sheet retreated to the retreat path, and  FIG. 13B  illustrates a state where an adhesive is applied (transferred) onto the first paper sheet stopped at the bonding position; 
         FIGS. 14A and 14B  are sheet flow diagrams continued from  FIG. 13B , in which  FIG. 14A  illustrates a state where an adhesive-applied position of the first paper sheet is retreated to the retreat path, and  FIG. 14B  illustrates a state where a second paper sheet is carried into the stacker section from the carry-in path; 
         FIGS. 15A and 15B  are sheet flow diagrams continued from  FIG. 14B , in which  FIG. 15A  illustrates a state where sheet alignment is performed with a leading end of the second paper sheet abutting against the stopper section and overlapped with the leading end of the first paper sheet, and  FIG. 15B  illustrates a state where the rear ends of the first and second paper sheets pass through the branching point between the carry-in path and retreat path; 
         FIGS. 16A and 16B  are sheet flow diagrams continued from  FIG. 15B , in which  FIG. 16A  illustrates a state where the first and second paper sheets are moved to the bonding position while being gripped by the gripper, where adhesive application and sheet pressing are performed, and  FIG. 16B  illustrates a state where carry-in of a third paper sheet is waited for with the adhesive-applied position of the first and second paper sheets in a bundled state retreated to the retreat path; 
         FIGS. 17A and 17B  are sheet flow diagrams continued from  FIG. 16B , in which  FIG. 17A  illustrates a state where sheet alignment is performed with a leading end of the last third paper sheet abutting against the stopper section, and  FIG. 13B  illustrates a state where the first to third paper sheets are moved to the bonding position while being gripped by the gripper, where adhesive application is performed; 
         FIGS. 18A and 18B  are sheet flow diagrams continued from  FIG. 17B , in which  FIG. 18A  illustrates a state where a rear end of the third paper sheet once passes through the branching point between the carry-in path and retreat path, and  FIG. 18B  illustrates a state where all the first to third paper sheets are switchback-conveyed to the retreat path; 
         FIG. 19  is a sheet flow diagram continued from  FIG. 18B , illustrating a folding processing standby state where the first to third paper sheets are positioned at a folding position; 
         FIGS. 20A to 20D  are explanatory views of a folding roller mechanism in the device illustrated in  FIG. 2 , in which  FIG. 20A  illustrates a state where the paper sheet bundle is stored,  FIG. 20B  illustrates a state where the paper sheet bundle is inserted between a pair of folding rollers by a folding blade,  FIG. 20C  illustrates a state where an initial state of the folding processing by the folding roller pair, and  FIG. 20D  illustrates a state where the paper sheet bundle is being folded by the folding roller pair; 
         FIGS. 21A to 21C  are explanatory views each illustrating a relationship between a sheet pressing slider illustrated in  FIGS. 3, 4, and 6  and a platen, in which  FIG. 21A  is an enlarged view of a bottom surface of the sheet pressing slider,  FIG. 21B  is an explanatory view explaining a position at which a transfer head applies an adhesive tape onto the paper sheet, and  FIG. 21C  is a view explaining a state where the last paper sheet is not applied with the adhesive but pressed by the sheet pressing slider (here, a fourth paper sheet is the last paper sheet); 
         FIGS. 22A and 22B  are modifications of a pressing mechanism of the sheet pressing slider illustrated in  FIGS. 21A to 21C , in which  FIG. 22A  illustrates a mechanism that uses a pressure roller as the sheet pressing member, and  FIG. 22B  illustrates a mechanism that uses a pair of rollers as the sheet pressing member; and 
         FIG. 23  is an explanatory view of a control configuration in the entire configuration illustrated in  FIG. 1 . 
     
    
    
     DESCRIPTION OF THE EMBODIMENTS 
     Hereinafter, the present invention will be described based on a preferred embodiment illustrated.  FIG. 1  is an explanatory view illustrating an entire configuration in which an image forming device and a sheet processing device according to the present invention are combined,  FIG. 2  is an explanatory view illustrating an entire configuration of the sheet processing device, and  FIG. 3  and subsequent figures are explanatory views each illustrating a mechanism configuration of the sheet processing device. A configuration illustrated in  FIG. 1  is constituted by an image forming device A and a sheet processing device B, and an adhesive application device  50  is integrated as a unit in the sheet processing device B. 
     [Configuration of Image Forming Device] 
     The image forming device A illustrated in  FIG. 1  feeds a paper sheet from a sheet supply section  1  to an image forming section  2 , performs printing on the paper sheet in the image forming section  2 , and discharges the paper sheet after printing from a main body discharge port  3 . Paper sheets of a plurality of sizes are accommodated in sheet cassettes  1   a ,  1   b , and  1   c  of the sheet supply section  1 , and the sheet supply section  1  separates, one from the other, paper sheets of a specified size and feeds them one by one to the image forming section  2 . The image forming section  2  includes, e.g., an electrostatic drum  4  and a print head (laser emitter)  5 , a developing unit  6 , a transfer charger  7 , and a fixing unit  8  which are disposed around the electrostatic drum  4 . An electrostatic latent image is formed on the electrostatic drum  4  using the laser emitter  5 , the developing unit  6  adds toner to the image, the transfer charger  7  transfers the image onto the paper sheet, and the fixing unit  8  thermally-fixes the image. The paper sheet with thus formed image is sequentially carried out from the main body discharge port  3 . A reference numeral  9  in  FIG. 1  denotes a circulation path, which is a path for two-side printing in which the paper sheet printed on the front side from the fixing unit  8  is reversed via a main body switchback path  10  and is conveyed to the image forming section  2  again for printing on the back side of the paper sheet. The paper sheet thus printed on both sides is reversed in the main body switchback path  10  and is carried out from the main body discharge port  3 . 
     A reference numeral  11  in  FIG. 1  denotes an image reader, where a document sheet set on a platen  12  is scanned by a scan unit  13  and is electrically read by a photoelectric conversion element  14  through a reflective mirror and a condensing lens. This image data is subjected to, e.g., digital processing by an image processor and is subsequently transferred to a data storage section  17 , and an image signal is sent to the laser emitter  5 . A reference numeral  15  denotes a document feeder that feeds document sheets stored in a stacker  16  to the platen  12 . 
     The image forming device A having the above-described configuration is provided with a control section (controller). Image forming conditions such as, printout conditions such as a sheet size specification, a color or black-and-white printing specification, a print copy count specification, single- or double-side printing specification, and enlarged or reduced printing specification are set via a control panel  18 . On the other hand, in the image forming device A, image data read by the scan unit  13  or transferred through an external network is stored in the data storage section  17 . The image data stored in the data storage section  17  is transferred to a buffer memory  19 , which sequentially transfers data signals to the laser emitter  5 . 
     Simultaneously with the image forming conditions, post-processing conditions are input and specified via the control panel  18 . For example, a “printout mode”, a “stapling mode”, and a “bonded paper sheet bundle folding mode” are specified as the post-processing conditions. The image forming device A forms an image on the paper sheet in accordance with the image forming conditions and the post-processing conditions. 
     [Configuration of Sheet Processing Device] 
     The sheet processing device B connected to the above-described image forming device A receives a paper sheet with the image formed thereon from the main body discharge port  3  of the image forming device A and is configured to (1) store the paper sheet in a first sheet discharge tray  21  (“printout mode” described above), (2) align the paper sheets from the main body discharge port  3  in a bundle to staple them and then store the paper sheets in the first sheet discharge tray  21  (“stapling mode” described above), or (3) align the paper sheets from the main body discharge port  3  in a bundle, then bond the paper sheets, fold the bonded paper sheets in a booklet form, and store the resultant paper sheets in a second sheet discharge tray  22  (“bonded paper sheet bundle folding mode” described above). 
     Thus, as illustrated in  FIG. 2 , the sheet processing device B is provided with the first sheet discharge tray  21  and second sheet discharge tray  22  in a casing  20 . Further, the device B is provided with a sheet carry-in path P 1  having a carry-in port  23  continued to the main body discharge port  3 . The sheet carry-in path P 1  is formed of a straight-line path in a substantially horizontal direction in the casing  20 . Further, there are provided a first switchback conveying path SP 1  and a second switchback conveying path SP 2  that branch off from the sheet carry-in path P 1  to convey a paper sheet in an inverse direction. The first switchback conveying path SP 1  branches off from the sheet carry-in path P 1  to the downstream side of the sheet carry-in path P 1 , the second switchback conveying path SP 2  branches off from the sheet carry-in path P 1  to the upstream side of the sheet carry-in path P 1 , and the paths SP 1  and SP 2  are disposed spaced apart from each other. 
     In such a path configuration, in the sheet carry-in path P 1 , there are disposed a carry-in roller  24  and sheet discharge roller  25 , and the rollers  24  and  25  are coupled to a drive motor (M 1 ) capable of rotating forward and backward. Further, in the sheet carry-in path P 1 , there is disposed a path switching piece  27  for guiding a paper sheet to the second switchback conveying path SP 2 , and the piece  27  is coupled to an operation means such as a solenoid. Further, the sheet carry-in path P 1  has, on the downstream side of the carry-in roller  24 , a punch unit  28  for punching the paper sheet from the carry-in port  23 . The illustrated punch unit  28  is disposed, on the upstream side of the carry-in roller  24 , at the carry-in port so as to be detachably mounted to the casing  20  depending on a device specification. Further, below the punch unit  28 , a punch chip box for housing punch chips generated upon the punch processing is detachably attached to the casing  20 . 
     [Configuration of First Switchback Conveying Path SP 1 ] 
     The first switchback conveying path SP 1  disposed, as illustrated in  FIG. 2 , on the downstream side (rear end portion of the device) of the sheet carry-in path P 1  is configured as described below. The sheet carry-in path P 1  is provided, at its exit end, with the sheet discharge roller  25  and a sheet discharge port  25   a . A first processing tray (hereinafter, referred to as “processing tray  29 ”) is provided downward of the sheet discharge port  25   a  across a level difference formed therebetween. The processing tray  29  includes a tray for loading and supporting the paper sheet discharged from the sheet discharge port  25   a . There is disposed, above the processing tray  29 , a forward/backward rotation roller  30 . The forward/backward rotation roller  30  is coupled with the forward/backward rotation motor M 1  and is controlled to be rotated in a clockwise direction in  FIG. 2  when a paper sheet approaches the processing tray  29 , while rotating in a counterclockwise direction after a paper sheet rear end enters the tray. The forward/backward rotation roller  30  has a lifting roller  31  coupled to a caterpillar belt so as to be movable between positions contacting the tray and separated therefrom. Therefore, the first switchback conveying path SP 1  is configured above the processing tray  29 . 
     Further, the first sheet discharge tray  21  is located downstream of the first switchback conveying path SP 1  and is configured to support a leading end of paper sheet guided to the first switchback conveying path SP 1  and second switchback conveying path SP 2 . 
     With the above-described configuration, the paper sheet from the sheet discharge port  25   a  reaches the processing tray  29  and is conveyed toward the first sheet discharge tray  21  by the forward/backward rotation roller  30 . Once the rear end of the paper sheet reaches the processing tray  29 , the forward/backward rotation roller  30  is reversely rotated (counterclockwise in the figure) to convey the paper sheet on the processing tray  29  in a direction opposite to a sheet discharge direction. At this time, the lifting roller  31  coupled to the caterpillar belt cooperates with the forward/backward rotation roller  30  to switchback-convey the rear end of the paper sheet along the processing tray  29 . 
     A rear end regulating member  33  and an end surface stapler  35  are disposed at a rear end portion of the processing tray  29  in the sheet discharge direction. The rear end regulating member  33  regulates a position of the rear end of the paper sheet. The illustrated end surface stapler  35  staples rear end edge of a paper sheet bundle stored on the tray at one or more positions. The rear end regulating member  33  is also used to provide a function of carrying out the stapled paper sheet bundle to the first sheet discharge tray  21  located downstream of the processing tray  29 . To this end, the rear end regulating member  33  is configured to be able to reciprocate in the sheet discharge direction along the processing tray  29 . The illustrated rear end regulating member  33  is coupled to a not illustrated bundle discharge motor (M 7 ) so as to be reciprocated. 
     The processing tray  29  has a side aligning plate  36  with which the paper sheets stored on the tray are aligned in a width direction thereof. The side aligning plate  36  includes a pair of left and right (front and rear in  FIG. 2 ) aligning plates so as to align the paper sheets with reference to a sheet center and is configured to approach and leave the sheet center. The side aligning plate  36  is coupled to a not illustrated side aligning plate motor (M 6 ). 
     The first switchback conveying path SP 1  configured as described above aligns the paper sheets from the sheet discharge port  25   a  on the processing tray  29  in the “stapling mode” described above, and the end surface stapler  35  staples the paper sheet bundle at one or more portions of the rear end edge of this paper sheet bundle. In the “printout mode”, a paper sheet from the sheet discharge port  25   a  is not subjected to the switchback, but the paper sheet conveyed along the processing tray  29  is carried out to the first sheet discharge tray  21  by the forward/backward rotation roller  30 . Thus, the illustrated device is characterized in that the sheet to be stapled is bridged between the processing tray  29  and the first sheet discharge tray  21  to allow the device to be compactly configured. 
     [Configuration of Second Switchback Conveying Path SP 2 ] 
     The following describes a configuration of the second switchback conveying path SP 2  branching off from the sheet carry-in path P 1 . As illustrated in  FIG. 2 , the second switchback conveying path SP 2  is located in a substantially vertical direction inside the casing  20 . A path carry-in roller  45  is located at an entrance of the second switchback conveying path SP 2 , and a conveying roller  46  is located at an exit of the second switchback conveying path SP 2 . The conveying roller  46  is configured to be movable between a position nipping the paper sheet and a position separated from the paper sheet. This configuration will be described later in detail. 
     The path carry-in roller  45 , located at the entrance of the second switchback conveying path SP 2 , is configured to be rotatable forward and backward. A sheet to be carried in the first switchback conveying path SP 1  located downstream is temporarily held (temporarily reside) on the second switchback conveying path SP 2 . The reason for the temporary holding is as follows. That is, the preceding paper sheets are stored on the processing tray  29 , stapled in response to a job completion signal, the resultant paper sheet bundle is carried out to the first sheet discharge tray  21 . During this carry-out, a paper sheet conveyed from the image forming device A to the sheet carry-in path P 1  is temporarily held on the second switchback conveying path SP 2 . Then, after the processing of the preceding paper sheet bundle is finished, the standing-by sheet is conveyed from the first switchback conveying path SP 1  onto the processing tray  29 . 
     A stacker section  40  constituting the second processing tray that aligns and temporarily stores the paper sheets conveyed along the second switchback conveying path SP 2  is provided downstream of a carry-in path  41  constituting the second switchback conveying path SP 2  and serving also as a paper sheet carry-in path. The illustrated stacker section  40  includes a conveying guide that conveying the paper sheets. The conveying guide is constituted by a stacker upper guide  40   a  and a stacker lower guide  40   b  and configured so that the paper sheets are loaded and housed therein. The illustrated stacker section  40  is connected to the carry-in path  41  and located in a center portion of the casing  20  in the left-right direction so as to extend in the substantially vertical direction. This allows the device to be compactly configured. The stacker section  40  is shaped to have an appropriate length to house maximum sized paper sheets therein. There are provided, inside the stacker section  40 , an adhesive application device  50  as an adhesive applying section for applying an adhesive to the paper sheet and a folding section  80  including a folding blade  86  and a folding roller  81  for folding the paper sheet. These components will be described later in detail. 
     [Configuration of Retreat Path (Third Switchback Path SP 3 )] 
     A retreat path  47  constituting a third switchback path SP 3  is continuously provided from a rear end side of the stacker section  40  in a sheet conveying direction. The retreat path  47  branches off from the carry-in path  41  constituting the above-described second switchback conveying path SP 2  and serving also as a path for carrying the paper sheet in the stacker section  40  and configured to overlap an exit end of the carry-in path and make the paper sheet advance thereinto in a switchback manner. As illustrated in  FIGS. 2 and 3 , the retreat path  47  is constituted by a switchback guide  42  formed of a plate material. Ribs are formed on a surface of the switchback guide  42  along the sheet conveying direction to smooth sheet conveying operation. Further, to cope with a case where a jam of the paper sheet bundle occurs in the retreat path, the switchback guide  42  is configured to turn about a guide releasing shaft  43  to be released. 
     When the rear end of the paper sheet carried in from the carry-in path  41  to the stacker section  40  passes through a position at which the retreat path  47  branches off from the carry-in path  41 , the paper sheet is moved (lifted up) by a stopper section  90  as a regulating member for regulating the leading end of the paper sheet, and the rear end side of the paper sheet is switchback-conveyed to the retreat path  47  together with the paper sheet bundle in the stacker section  40 . 
     The stopper section  90  as the regulating member for regulating the leading end of the paper sheet also serves as a moving member for moving the paper sheet by means of a gripper  91  to be described later for gripping the paper sheet. Although the regulating member and moving member may be separately provided, the functions thereof are achieved by a single member (stopper section  90 ) in the present embodiment. 
     At a merging point between the carry-in path  41  and retreat path  47 , a deflection guide  44  biased by a guide tension spring  44   a  toward the switchback guide  42  side of the retreat path  47  is provided. Further, at the merging point, the adhesive application device  50  for applying an adhesive onto the paper sheet is located so as to immediately follow the deflection guide  44 . The adhesive application device  50  has adhesive tape stampers  51  each serving as a bonding member. Although details will be described later, when a paper sheet (second paper sheet) is carried in from the carry-in path  41  after an adhesive tape is applied (transferred) onto a preceding paper sheet (first paper sheet) by the adhesive tape stampers  51  of the adhesive application device  50 , the leading end of the second paper sheet is adhered to the adhesive-applied portion of the first paper sheet, making it impossible to apply the adhesive onto a center portion of the second paper sheet in the sheet conveying direction, thus failing to form a paper sheet bundle. For this reason, it is necessary to convey the paper sheet to the adhesive tape stampers  51  after the preceding sheet is switchback-conveyed to the retreat path  47 . Thus, the retreat path  47  functions as a retreat path for the adhesive-applied paper sheet. 
     Further, by switching back the paper sheet to the retreat path  47 , a leading end of a paper sheet to be conveyed by the conveying roller  46  of the carry-in path  41  and a rear end of a paper sheet (preceding paper sheet) that has been loaded on and supported by the stacker section  40  are overlapped with each other, thereby keeping the page order of the paper sheets to be stored. 
     [Outline of Configurations of Components Provided Along Path Between Retreat Path and Stopper Section] 
     Based on  FIGS. 2 and 3 , an outline of configurations of components provided along a path between the retreat path  47  and stopper section  90  will be described. 
     At the merging point between the carry-in path  41  and retreat path  47 , the deflection guide  44  is provided, in which a spring is stretched so as to slightly press the paper sheet toward the switchback guide  42  of the retreat path  47 . The deflection guide  44  has such a comb shape as to avoid the adhesive-applied portion of the paper sheet. Thus, even when the adhesive-applied paper sheet passes under the deflection guide  44 , the adhesive is not adhered to the conveying path. A flow of the paper sheet in this section will be described separately later. 
     As illustrated in detail in  FIG. 3 , at the merging point between the carry-in path  41  on the downstream side of the deflection guide  44  and retreat path  47 , the adhesive application device  50  for applying an adhesive onto the paper sheet is provided in the stacker section  40 . A sheet presser  65  for pressing, toward the stopper section  90 , a paper sheet stopped at a bonding position for regulation is mounted to the adhesive application device  50  so as to be vertically movable. Further, a sheet pressing slider  71  configured to be moved vertically to press the paper sheet and feed an adhesive tape AT as an adhesive is provided on a leading end side of the sheet presser  65 . A transfer head  72  for backing up the adhesive tape AT fed from a reel is provided above the sheet pressing slider  71 . The transfer head  72  is also moved between the bonding position at which it presses the paper sheet to apply the adhesive tape AT onto the paper sheet and a separated position at which it is separated from the paper sheet to allow the paper sheet to be conveyed/moved therethrough. 
     The “application” in the present invention includes so-called “transfer” that transfers the adhesive from a tape to the paper sheet by pressing the paper sheet. Further, the “application” includes spraying of the adhesive to the paper sheet while pressing the paper sheet. 
     A sheet side edge aligning member  48  configured to be moved in the sheet width direction to press a side edge of the paper sheet in the stacker section  40  is disposed on both sides of a downstream side of the adhesive application device  50 . The sheet side edge aligning member  48  has a substantially U-like shape, at a center portion of which folding rollers  81   a  and  81   b  serving as the folding section and the folding blade  86  for pressing the paper sheet against the folding rollers  81   a  and  81   b  are movably provided so as to press and separate from the paper sheet. Further, a pressure roller  49  is provided so as to immediately follow the sheet side edge aligning member  48  and to contact and separate from the stacker lower guide  40   b  which is one of the guide members constituting the stacker section  40 . The pressure roller  49  is separated from the paper sheet until the leading end of the paper sheet passes therethrough and, after the sheet leading end passes through the pressure roller  49 , the pressure roller  49  is rotated while pressing the paper sheet against the stacker lower guide  40   b.    
     A regulating member (hereinafter, referred to as “stopper section  90 ”) for regulating the leading end of the paper sheet in the sheet conveying direction is provided on a lower end side of the stacker section  40 . The stopper section  90  is supported by a guide rail of a device frame and is configured to be vertically movable along the stacker section  40  by an elevating belt  93  stretched between vertically arranged upper and lower pulleys  94   a  and  94   b . These bridge pulleys  94  are moved by the motor (M 1 ) to move the elevating belt  93 . As described below, the elevating belt  93  is configured to move the stopper section  90  to and stop the same at positions of Sh 1 , Sh 2 , Sh 3 , and Sh 4 . 
     The Sh 0 , which is the lowermost position, is a home position of the stopper section  90 . A sensor (not illustrated) is used to detect this position for initial position setting. The Sh 1  is a receiving position of a first paper sheet and a position at which the rear ends of the sequentially stacked paper sheets that have passed through the carry-in path are pressed by the deflection guide  44  toward the switchback guide of the retreat path  47 . The Sh 2  is a position at which the paper sheet bundle is subjected to the folding at a substantially half position of the paper sheet in the sheet conveying direction. The Sh 3  is a position at which the adhesive tape stampers  51  each serving as the bonding member is used to apply (transfer), in the sheet width direction, the adhesive tape AT onto the paper sheet at a substantially half position of the paper sheet in the sheet conveying direction. The Sh 4  is a position at which the adhesive-applied position at which the adhesive member (adhesive tape AT) is applied onto the paper sheet is moved to the retreat path  47 . More specifically, when a paper sheet (second paper sheet) is carried in from the carry-in path  41  into the stacker section  40 , the adhesive-applied position of the preceding paper sheet (firs paper sheet) can be retracted to a position (application concealing position  100 ) separated away from the carry-in path of a subsequent sheet so as to prevent a sheet jam or adhesion of the adhesive to an unintended position due to contact of the second paper sheet with the adhesive-applied position of the first paper sheet. In this device, carry-in of the paper sheet, application of the adhesive onto the paper sheet, movement of the adhesive-applied position to the retract path, carry-in of the subsequent paper sheet, and application of the adhesive onto the subsequent paper sheet are performed to bond the paper sheets by the adhesive, and the above operations are repeatedly performed to form the paper sheet bundle. The formation of the paper sheet bundle will be described in detail later in a step by step manner. 
     The resultant paper sheet bundle is then folded in two by the folding section  80  and discharged to the second sheet discharge tray by a bundle discharge roller  95  provided with a bundle kick-out piece  95   a . The discharged paper sheet bundle is stored on the second sheet discharge tray by a bundle press guide  96  for preventing a sheet loading range from being narrowed due to expansion of the bundle and a bundle presser  97  positioned downward of the bundle press guide  96 . 
     [Configuration of Adhesive Application Device] 
     The following describes the adhesive application device  50  with reference to  FIGS. 3 to 8 . A range surrounded by a dashed line of a cross-sectional view of  FIG. 3  corresponds to the adhesive application device  50 .  FIG. 4  is a perspective view of the adhesive application device  50 , and the adhesive application device  50  is attached to the sheet processing device B with an illustrated range as a unit.  FIGS. 5A to 5C  are explanatory views of a main part of adhesive tape units  50   a ,  50   b , and  50   c  constituting an adhesive unit.  FIG. 5A  is a plan view of a cam member  57  and the like.  FIG. 5B  is a front view illustrating an engagement state between the cam member  57  and a stamper holder  52 . An upper stage of  FIG. 5C  illustrates a state where the cam member  57  is moved to a position causing the adhesive tape stampers  51  to be separated from the paper sheet, and a lower stage of  FIG. 5C  illustrates a state where the cam member  57  is moved to a position causing the stamper holder  52  to be pressed against the platen  79 , at which the adhesive tape stampers contact the paper sheet. 
       FIGS. 6A to 6D  are explanatory views of the adhesive tape stampers  51  each serving as a bonding member.  FIG. 6A  is a perspective view,  FIG. 6B  is a internal mechanism view, and  FIGS. 6C and 6D  are views for explaining a drive mechanism for winding the adhesive tape AT in a stamping operation.  FIGS. 7A to 7C  and  FIGS. 8A to 8C  are explanatory views illustrating an operation of applying/transferring the adhesive tape onto the paper sheet performed by the adhesive tape units  50   a  and  50   b  each supporting a plurality of adhesive tape stampers  51 . 
     A range surrounded by a dashed line of  FIG. 3  corresponding to the adhesive application device  50  in the present embodiment. There are disposed, within the dashed-line range, an adhesive tape stamper  51  as a bonding member, a stamper holder  52  as a bonding unit for grouping the adhesive tape stampers  51  and supporting them in parallel, a cam member  57  that moves vertically stamper holder  52  between a position at which the stamper holder  52  is brought close to a platen  79  to press the adhesive tape stampers  51  against the paper sheet for application of the adhesive onto the paper sheet and a position at which the stamper holder  52  is separated from the platen  79 , and a cam moving motor  60  (M 13 ) that moves the cam member  57  in a direction crossing the sheet conveying direction. Further, a plurality of adhesive tape units  50   a  and  50   b  are configured to be attachable to the sheet processing device B, more specifically, to an upstream position of the stacker section  40  as a unitized adhesive application device  50 . Further, in order to prevent the paper sheet from being shifted upon carry-in of the paper sheet into the stacker section  40  or switchback thereof to the retreat path  47 , a part of the carry-in path  41  (more specifically, a portion from a unit path entrance  143  to a carry-in path exit  144 ), deflection guide  44 , a part of the branching retreat path  47  (more specifically, a retreat path exit  145 ), and platen  79  are incorporated in the adhesive application device  50  as a unit. The adhesive application device  50  corresponding to the range surrounded by the dashed line of  FIG. 3  is thus configured and is illustrated in a perspective view of  FIG. 4 . 
     Attachment of the adhesive application device  50  to the sheet processing device B is made by fixing a not illustrated fixing portion of the sheet processing device B and a stop screw hole  50   cb  formed in a frame of the adhesive application device  50  by an illustrated screw, as illustrated in  FIG. 4 . In place of the fixing structure using the screw, rails may be provided in the sheet processing device B and adhesive application device  50 , respectively, so as to allow the adhesive application device  50  to be pulled out. 
     The above unitized configuration allows an increase in accuracy of a positional relationship among the components as compared to a case where the components are individually attached to the sheet processing device B, thereby, in particular, suppressing adhesion of the adhesive to an unintended position due to displacement upon movement of the paper sheet after application of the adhesive. 
     In the adhesive application device  50 , left and right application device frames  50   c , a center support frame  63 , a rear support frame  64   a , and a lower support frame  64   b  constitute one casing. The center support frame  63  connects the left and right application device frames  50   c  at center portions thereof. The rear support frame  64   a  connects the left and right application device frames  50   c  at rear portions thereof. The lower support frame  64   b  connects the left and right application device frames  50   c  at portions thereof below the platen  79 . The cam moving motor  60  is mounted to the one of the left and right application device frames  50   c . Drive of the cam moving motor  60  is transmitted to a moving belt  58  through a gear train  59 . The moving belt  58  is connected to the cam member  57  which is configured to be slidable along two cam guide rods  57   a  extending between the left and right application device frames  50   c  in the sheet width direction. Thus, when the cam moving motor  60  is driven, the cam member  57  is moved to the left or right according to a rotating direction of the cam moving motor  60 . 
     Cam grooves  61  as illustrated in  FIGS. 5B and 5C  are formed in the cam member  57 . As illustrated, the cam member  57  includes an upper horizontal cam groove  61   a , a lower horizontal cam groove  61   c , and an inclined cam groove  61   b . The upper horizontal cam groove  61   a  is positioned at an upper portion of the cam member  57 . The lower horizontal cam groove  61   c  is positioned at a lower portion of the cam member  57 . The inclined cam groove  61   b  connects the upper horizontal cam groove  61   a  and lower horizontal cam groove  61   c . As illustrated, two left and right cam grooves  61  are formed in the cam member  57  and are slightly different in phase. A roller  56  serving as a cam follower and fixed to a moving block  54  for moving vertically the stamper holder  52  is fitted into each of the cam grooves  61 . 
     The roller engaged with (fitted into) each cam member  61  is fixed to the moving block  54  through a shaft. Referring to  FIG. 7A  (which is an explanatory view as viewed from the back of the cam member  57  of  FIG. 4 ), the moving block  54  is slidably supported by inner two guide rods  53  of four guide rods  53  provided in the stamper holder  52  that supports the adhesive tape stamper  51  so as to vertically extend. On the other hand, each of the remaining (outer) two guide rods  53  is slidably supported by a support block  55  fixed to the center support frame  63  connecting the left and right application device frames  50   c . Accordingly, the stamper holder  52  supporting the adhesive tape stamper  51  is supported by the support block  55  in which the outer guide rods  53  slide. 
     On the other hand, the moving block  54  is mounted to the two guide rods  53  at a center of the stamper holder  52  so as to be freely slidable. The moving block  54  is fixed to the roller  56  engaged, as a cam follower, with the above cam groove  61 . Further, a pressure spring  62  is wound around the center two guide rods  53  between a bottom surface of the moving block  54  and a rear surface  52   c  of a bottom surface of the stamper holder  52 . The pressure spring  62  constantly biases the moving block  54  in a direction pressing the same against an upper portion of the stamper holder  52 . Accordingly, when the cam member  57  is moved to cause the roller  56  engaged with the cam groove  61  to descend, a transfer head  72  to be described later of the adhesive tape stamper  51  abuts against the paper sheet to stop the descent of the stamper holder  52 . Then, the pressure spring  62  is compressed between the bottom surface of the moving block  54  and rear surface  52   c  of the bottom surface of the moving block  54 . As a result, the transfer head  72  is pressed more strongly against the paper sheet by an elastic force of the pressure spring  62  compressed by the moving block  54 , allowing the adhesive on the transfer tape AT to be reliably applied (transferred) onto the paper sheet. 
     Further, as illustrated in  FIG. 5C , the left and right cam grooves  61  with which the roller  56  is engaged are different in phase and initial position of the roller  56 . Thus, the left side roller  56  starts to descend earlier, and the right side roller  56  reaches the lower horizontal cam groove  61   c  later. Therefore, the left side lower horizontal cam groove  61   c  is formed longer than the right side lower horizontal cam groove  61   c . As a result, the adhesive tape unit  50   a  presses the paper sheet earlier than the adhesive tape unit  50   b , and the adhesive tape unit  50   b  presses the paper sheet later. A considerable pressing force is required in order for the adhesive tape units  50   a  and  50   b  press the paper sheet at a time, so that a more powerful drive motor needs to be used to move the cam member  57 ; however, by deviating the timing of pressing the paper sheet as described above, it is possible to reduce a size of the motor or weight of the frame. This further makes it unlikely to generate wrinkles or twist in the paper sheet. 
     [Bonding Member (Adhesive Tape Stamper)] 
     The adhesive tape stamper  51  configured to be mountable to the stamper holder  52  constituting the adhesive tape units  50   a  and  50   b  will be described using  FIGS. 6A to 6D .  FIG. 6A  illustrates an outer appearance of the adhesive tape stamper  51 . There are shown, in  FIG. 6A , a stamper cover  70 , a transfer tape AT having an adhesive on a tape base material and configured to be sequentially delivered, a transfer head  72  around which the transfer tape AT is wound and configured to back up the transfer tape AT so as to press the same against the paper sheet, and a sheet pressing slider  71  positioned beside the transfer head  72  and configured to be moved vertically between a position protruding from the transfer head  72  and a retreat position corresponding to the transfer head  72 . When the transfer head  72  is moved down and applies/transfers the transfer tape AT onto the paper sheet, the sheet pressing slider  71  presses the paper sheet positioned thereunder. With this pressing operation, the transfer tape AT is delivered, and a new adhesive surface is delivered. The transfer head  72  then backs up and presses the adhesive surface to thereby apply/transfer the adhesive onto the paper sheet. 
     The following describes a configuration in which extension/contraction of the sheet pressing slider  71  delivers the transfer tape AT. As illustrated in  FIG. 6B , there are disposed, inside the stamper cover  70 , a supply reel  74  freely rotatable about a supply reel shaft  74   a , around which an unused transfer tape AT is wound and a winding reel  75  free rotatable about a winding reel shaft  75   a  and configured to wind the transfer tape AT that is delivered from the supply reel  74  and stretched over the transfer head  72 .  FIG. 6C  illustrates a state before the transfer tape AT is delivered from the supply reel  74 . Above the sheet pressing slider  71  provided inside the stamper cover  70  so as to be extendable/contractible, a resin slider rack  77  is provided. The slider rack  77  is engaged with a gear rotating together with the winding reel  75 . Further, the gear of the winding reel  75  is engaged with a gear rotating together with the supply reel  74  through inter-reel gears  76 . 
     Further, a slider spring  73  is provided in the sheet pressing slider  71  and constantly biases outward (downward in  FIGS. 6A to 6D ) the sheet pressing slider  71 . Thus, when the adhesive tape stamper  51  in a state of  FIG. 6D  is pressed down in a state of  FIG. 6C  where the slider spring  73  is extended, the slider spring  73  is compressed. At the same time, the slider rack  77  is engaged with a winding reel gear  75   b  of the winding reel  75  to rotate the winding reel  75  in a clockwise direction in the drawing. The winding reel gear  75   b  is engaged with one of the inter-reel gears  76 , and the other one of the inter-reel gears  76  is engaged with a supply reel gear  74   b . Thus, when the winding reel  75  is rotated in the clockwise direction in the drawing, the supply reel  74  is also rotated to cause the adhesive tape AT to be wound around the winding reel. At the same time, the transfer tape AT is delivered from the supply reel, and a new adhesive surface is positioned at the transfer head  72 . 
     Then, when the adhesive tape stamper  51  is moved up in the state of  FIG. 6D , the slider spring  73  is elastically restored to press down the sheet pressing slider  71 . At this time, the winding reel gear  75   b  is engaged with the slider rack  77  and is thus rotated in a counterclockwise direction; however, a ratchet mechanism that transmits rotation only in one direction is interposed between the winding reel gear  75   b  and winding reel  75 , so that the winding reel  75  is not rotated. Further, the inter-reel gear  76  engaged with the winding reel gear  75   b  and supply reel gear  74   b  are also rotated in the counterclockwise direction; however, a ratchet mechanism that transmits rotation only in one direction is interposed between the supply reel gear  74   b  and supply reel  74 , so that the supply reel  74  is not rotated. With this mechanism, only when the sheet pressing slider  71  is pressed down, the supply reel  74  and winding reel  75  are rotated, and a new adhesive surface of the adhesive tape AT is delivered to the transfer head and positioned thereat. In the present embodiment, as the ratchet mechanisms which are not illustrated, a one-way clutch that transmits rotation only in one direction between the reel gear and reel may be adopted. 
     The movement from the state of  FIG. 6C  to state of  FIG. 6D  is made by the cam member  57  vertically moving the stamper holder  52  that supports a plurality of adhesive tape stampers  51 . This mechanism is as described above. Note that, as illustrated in  FIG. 3 , a foamed resin cushion material  52   a  for buffering an impact upon the vertical movement is interposed between the stamper holder  52  and adhesive tape stamper  51 . This improves application (transfer) performance of the adhesive from the adhesive tape AT onto the paper sheet. 
     By the way, the adhesive tape AT in the present embodiment has the adhesive on the tape base material and is configured to press the tape base material against the paper sheet to thereby transfer the adhesive onto the paper sheet. 
     [Sheet Bundle Presser Adjacent to Stamper Holder] 
     The following describes, using  FIGS. 3 and 4 , and particularly  FIG. 7A , a sheet presser  65  that prevents movement or flapping of the paper sheet before the sheet pressing slider  71  of the adhesive tape stamper  51  described using  FIGS. 6A to 6D  presses the paper sheet against the platen  79  as the bonding position. 
     As described above, the sheet presser  65  for regulating the paper sheet stopped at the bonding position for bonding is mounted to the adhesive application device  50  so as to be vertically movable with respect to the platen  79 . As illustrated in  FIG. 7A , there is provided, on both side of the two stamper holders  52  each supporting the adhesive tape stampers  51 , a sheet presser support block  67  that slidably supports a sheet presser guide rod  68  having the sheet presser  65 . The sheet presser support block  67  is fixed to the center support frame  63  by screws or the like inserted into round holes formed therein. Further, a pressing pressure spring  65   c  wound around the sheet presser guide rod  68  is provided at both side ends of the sheet presser support block  67  and a side edge presser  65   a  of the sheet presser  65 . 
     The sheet presser  65  is constantly biased in a direction pressing the paper sheet, and one (left side of  FIGS. 7A to 7C ) stamper holder  52  and sheet presser  65  are engaged with each other through an engagement portion  69  to stop the sheet presser  65  at a position separated from the paper sheet on the platen  79 . Thus, when the stamper holder  52  is not moved down with the movement of the cam member  57 , the sheet presser  65  stays at the position separating from the paper sheet, allowing passage of the paper sheet. When the stamper holder  52  starts being moved down toward the paper sheet with the movement of the cam member  57 , the engagement portion between the stamper holder  52  and sheet presser  65  is moved down as illustrated in  FIG. 7C , and the sheet presser  65  is moved down to prevents displacement or flapping of the paper sheet on the platen  79 . This can prevents the displacement or flapping of the paper sheet when the stamper holder  52  is moved down to cause the sheet pressing slider  71  to press the paper sheet, or when the stamper holder  52  is further moved down to cause the transfer head  72  supporting the adhesive tape AT and pressing the same against the paper sheet to press the paper sheet. 
     After each adhesive tape stamper  51  applies (transfers) the adhesive of the adhesive tape AT onto the paper sheet in the width direction thereof with the moving down of the two stamper holders  52 , when the cam member is returned to a state of  FIG. 7B , the engagement portion of the sheet presser  65  is engaged with the stamper holder  52  and moved up to a position retreated from the paper sheet by moving up of the stamper holder  52 . As described above, the sheet presser  65  presses the paper sheet, interlocking with the vertical movement of the stamper holder  52 , before other members do. This sheet presser may be moved down before the moving down of the stamper holder  52  by means of a solenoid or the like. Further, although the side edge presser  65   a  and a center presser  65   b  are provided so as to press the paper sheet over the entire width thereof, only one of them suffices. That is, it is only necessary to prevent the paper sheet from being moved before application of the adhesive. 
     [Operation of Adhesive Application Device] 
     The following describes an operation of applying (transferring) the adhesive onto the paper sheet by the adhesive application device  50  using  FIGS. 7A to 7C  and  FIGS. 8A to 8C .  FIGS. 7A to 7C  and  FIGS. 8A to 8C  are each an explanatory view as viewed from the back of the cam member  57 . 
     In a state of  FIG. 7A , the cam member  57  is situated at an initial position, and the moving block  54  that makes the stamper holder  52  mounted with the adhesive tape stampers  51  slide along the inner guide rods  53  and roller  56  are engaged with the cam groove  61  of the cam member  57 . As described above, the moving block  54  has the pressure spring  62  which is interposed between itself and the moving block  54  and brings the pressure spring  62  into contact with and presses the rear surface  52   c  of the stamper holder  52 , as illustrated in  FIG. 7A . Further, the stamper holder  52  is configured to slide along the outside guide rods  53  slidably supported by the support block  55  fixed to the center support frame  63  connecting the left and right application device frames  50   c  so as to be moved vertically. 
     In  FIG. 7A , the stamper holder  52  and the sheet presser  65  locked to the stamper holder  52  are separated from the platen  79 , thereby maintaining a space for allowing passage of the paper sheet. In this state, the sheet pressing slider  71  and transfer head  72  of each adhesive tape stamper  51  are situated at a position farthest from the paper sheet. The other stamper holder  52  is situated at the same position. 
     In  FIG. 7B , the paper sheet is situated at the bonding position, and the cam moving motor  60  is driven by a signal for commanding application of the adhesive tape AT to move the cam member  57  to the right in the drawing. Then, the roller  56  on the left side in the drawing starts being moved down along the inclined cam groove  61   b . This movement causes the left side stamper holder  52  to be moved down with the support block  55  sliding along the guide rods  53 . The moving down of the stamper holder  52  causes the engagement portion  69  engaged with the stamper holder  52  to be moved down, thereby starting pressing the paper sheet on the platen  79 . On the other hand, the sheet pressing slider  71  and transfer head  72  of each adhesive tape stamper  51  are also moved down, but do not contact the paper sheet. The stamper holder  52  on the right side in the drawing is not moved down since the roller  56  is only slid in the upper horizontal cam groove  61   a  of the cam groove  61 . 
     When the cam member  57  is further moved, the roller  56  on the left side in the drawing is further slid down along the inclined cam groove as illustrated in  FIG. 7C . This sliding down releases the engagement between the sheet presser  65  and right side stamper holder  52  which are engaged with each other at the engagement portion  69 . When the engagement is released, the sheet presser  65  presses the paper sheet more reliably for position regulation by means of the pressing pressure spring  65   c  interposed between itself and sheet presser support block  67 . On the other hand, the sheet pressing slider  71  of the adhesive tape stamper  51  starts to contact the paper sheet. With this contact, the adhesive tape AT is moved from the state of  FIG. 6C  to state of  FIG. 6D  to expose a new adhesive surface. In this state, the transfer head  72  has not yet contact the paper sheet. The stamper holder  52  on the right side in the drawing is not moved down since the roller  56  is only slid in the upper horizontal cam groove  61   a  of the cam groove  61 . 
     Subsequently, when the cam member  57  is moved to the right as illustrated in  FIG. 8A , the stamper holder on the left side in the drawing is moved down to cause the sheet pressing slider  71  and transfer head  72  to abut against the paper sheet. When the transfer head  72  abuts against the paper sheet, the moving down of the stamper holder  52  is stopped, while the moving block  54  is slid along the inclined cam groove  61   b  and moved down. With this movement, the pressure spring  62  starts being compressed, and the elastic force of the pressure spring  62  acts on the transfer head  72  through the stamper holder  52  as a pressurizing force, with the result that the adhesive tape AT is pressed against the paper sheet more strongly. Thus, the adhesive can be reliably applied/transferred onto the paper sheet. 
     On the other hand, the roller  56  of the right side stamper holder  52  starts being slid down along the inclined cam groove  61   b , and the sheet pressing slider  71  of the adhesive tape stamper  51  of the right side stamper holder  52  starts pressing the paper sheet. 
     When the cam member  57  is further moved, a state of  FIG. 8B  is reached. In this state, the stamper holder  52  on the left side in the drawing is maintained in a pressurized state by the elastic force of the pressure spring  62 . On the other hand, the roller  56  of the stamper holder  52  on the right side in the drawing reaches an end point of the inclined cam groove  61   b , with the result that the sheet pressing slider  71  and transfer head  72  of the adhesive tape stamper  51  of the right side stamper holder  52  press the paper sheet. 
     When the cam member  57  is situated at the rightmost position as illustrated in  FIG. 8C , the left side stamper holder  52  is maintained in a more pressurized state by the elastic force of the pressure spring  62 . On the other hand, the roller  56  of the stamper holder  52  on the right side in the drawing reaches the lower horizontal cam groove  61   c , with the result that the sheet pressing slider  71  and transfer head  72  of the adhesive tape stamper  51  of the stamper holder  52  on the left side press the paper sheet and that the pressure spring  62  is compressed. This elastic force acts on the transfer head  72  through the stamper holder  52  as a pressurizing force, with the result that the adhesive tape AT is pressed against the paper sheet more strongly. Thus, the adhesive can be reliably applied (transferred) onto the paper sheet. 
     After all the transfer heads  72  of the left- and right-side stamper holders  52  have applied the adhesive onto the paper sheet by the moving down of the left- and right-side stamper holders  52 , the cam member  57  is moved to the left in the drawing to move up the stamper holder  52  in a reverse order of the moving-down procedure. When the state of  FIG. 7B  is reached, the stamper holder  52  on the left side is engaged with the engagement portion  69  of the sheet presser  65  to move the sheet presser  65  to a position separated from the paper sheet. Subsequently, the state of  FIG. 7A  is restored, and the application of the adhesive onto a next paper sheet is prepared for. 
     As described above, in the present embodiment, the paper sheet is previously pressed by the sheet presser  65  to prevent movement of the paper sheet before the transfer head  72  of the adhesive tape stamper  51  applies the adhesive onto the paper sheet. This prevents displacement or flapping of the paper sheet, thus making it possible to apply the adhesive onto a predetermined position on the paper sheet. Further, even after the transfer head  72  abuts against the paper sheet, the stamper holder  52  that supports the transfer head  72  is pressed by the pressure spring  62 . This makes it possible to press the transfer head  72  against the paper sheet more strongly, allowing the adhesive on the adhesive tape AT to be reliably transferred onto the paper sheet. 
     Further, as described in the explanation of the operation of the adhesive application device, the left and right stamper holders  52  illustrated in  FIGS. 7 and 8  do not press the transfer heads  72  simultaneously, but the timing of pressing the paper sheet is deviated such that first the left side transfer head  72  group is pressed against the paper sheet, and then the right side transfer head  72  group is pressed against the paper sheet while the pressuring state of the left side transfer head  72  group is maintained. Thus, it is possible to reduce a drive force as compared to a case where the both the left- and right-side transfer head  72  groups are pressed against the paper sheet at a time, which in turn can reduce a size of the cam moving motor  60 . Further, the device can be formed even with a slightly brittle frame structure, allowing a reduction in weight of the device. 
     The following sequentially describes the sheet side edge aligning member  48  positioned inside the stacker section  40  at a downstream side of the adhesive application device  50 , conveying roller  46  and pressure roller  49  which are configured to be separated from the paper sheet during the aligning operation, stopper section  90  that regulates a leading end of the paper sheet carried into the stacker section  40 , and gripper  91  provided in the stopper section  90  and configured to grip the paper sheet. 
     [Sheet Side Edge Aligning Mechanism] 
     As described above, the sheet side edge aligning member  48  configured to be moved in the sheet width direction to press a side edge of the paper sheet in the stacker section  40  is disposed on both sides of the downstream side of the adhesive application device  50 . A configuration of the sheet side edge aligning member  48  will be described more in detail using  FIG. 9 . The sheet side edge aligning member  48  includes, on both sides of the sheet width direction, an upstream side aligning plate  110  positioned at an upstream side in the sheet conveying direction, a downstream side aligning plate  111  positioned at a downstream side in the sheet conveying direction relative to the upstream side aligning plate  110 , and an aligning plate connecting portion  112  connecting the upstream- and downstream-side aligning plates  110  and  111 . An interval between the downstream side aligning plates  111  in the sheet width direction is slightly wider than that between the upstream side aligning plates  110 . Racks  114  extending in the sheet width direction are fixed respectively to the left and right aligning plate connecting portions  112  at their rack connecting portions  113 . A pinion  116  meshed with rack teeth is provided at a center of the left and right racks  114  and is connected to an aligning motor  117  (M 12 ). The pinion  116  is rotated by forward/backward rotation of the aligning motor  117 , and the upstream side aligning plate  110  and downstream side aligning plate  111  are reciprocated in the sheet width direction by the rack  114  meshed with the pinion  116 . As a result, side edges of the paper sheet are pressed for alignment. 
     Drive/rotation of the above aligning motor  117  is controlled by a sheet binding/bonding operation controller  201  to be described later. In the present embodiment, an application position at which the adhesive is applied onto the paper sheet for bonding is retreated to the retreat path  47 . This allows a new paper sheet to be bonded to be positioned in the carry-in path  41 . That is, it is possible to align the new and preceding paper sheets in a state where the leading ends thereof whose rear ends are positioned in the different paths (carry-in path  41  and retreat path  47 ) abut against the stopper section  90 . Further, the sheet side edge aligning member  48  is positioned at this position, allowing the alignment processing to be performed immediately before the bonding between the paper sheet on a surface of which the adhesive has been applied and a next paper sheet, which improves alignment accuracy of the paper sheet to be bonded. 
     [Separating Mechanism (Conveying Roller, Etc.)] 
     It is necessary to release nipping and pressure contact with the paper sheet upon the alignment operation of the sheet side edge aligning member  48 . This mechanism will be described using  FIGS. 10A and 10B .  FIG. 10A  illustrates a nipping and nipping release configuration of the conveying roller  46  positioned at the downstream side of the carry-in path  41 .  FIG. 10B  illustrates a pressure contact separating configuration of the pressure roller  49  which is positioned in the middle of the stacker section  40  and straight downstream of the folding section  80  and configured to press the paper sheet against the stacker lower guide  40   b  and apply a conveying force in a direction toward the stopper section  90  side. 
     First, the conveying roller  46  of  FIG. 10A  will be described. The conveying roller  46  is rotated by a roller transmission belt  124  that receives a drive force from a forward/backward rotation conveying motor M 2  includes a drive roller shaft  121 , a drive roller  120 , and a pinch roller  125  configured to contact and separated from the drive roller  120 . Release of the nipping of the conveying roller  46  is made by separation of the pinch roller  125  from the drive roller  120 . The pinch roller  125  includes a support bracket  126  supporting the pinch roller  125  and a turning shaft  127  that turnably support the support bracket  126 . The turning shaft  127  is fixed to a turning gear  129  at a device base end portion. The turning gear  129  is engaged with a separating motor  131  (M 3 ) through a separating motor gear  130 . A protruding pin  127   a  whose lower end side is embedded in the turning shaft  127  and whose upper end protrudes from the turning shaft  127  is engaged with a pin receiving groove  128  of the support bracket  126 . The pin receiving groove  128  is configured to allow the protruding pin  127   a  to be freely moved in a predetermined range. Further, a coil spring  122  wound around the turning shaft  127  is bridged between the support bracket  126  and a not illustrated device frame. 
     Thus, the coil spring  122  causes the pinch roller  125  to be constantly biased by the drive roller  120  and thereby applies a conveying force to the paper sheet. On the other hand, when a signal commanding separation of the pinch roller  125  from the drive roller  120  is output from a sheet conveying controller  195  upon operation of the sheet side edge aligning member  48 , the separating motor  131  for the pinch roller  125  is driven. The drive of the separating motor  131  causes the turning gear  129  fixed to the turning shaft to be rotated in a direction denoted by an arrow of  FIG. 10A  through the separating motor gear  130 . The rotation of the turning gear  129  causes the protruding pin  127   a  on the turning shaft  127  to be rotated in the pin receiving groove  128  in a direction denoted by an arrow of  FIG. 10A . Then, when the protruding pin  127   a  abuts against a protruding wall of the pin receiving groove  128 , the support bracket  126  is moved to separate the pinch roller  125  from the drive roller  120 , thereby releasing the nip with the paper sheet. Conversely, in order to bring the pinch roller  125  into pressure contact with the drive roller  120  for the sheet conveyance, the separating motor  131  is reversed. Then, the protruding pin  127   a  is positioned at a substantial center of the pin receiving groove  128 . Thus, the elastic force of the coil spring  122  causes the pinch roller  125  to be brought into pressure contact with the drive motor, whereby a constant conveying force can be applied to the paper sheet. 
       FIG. 10B  illustrates the pressure roller  49  configured to be movable so as to contact and separate from the stacker lower guide  40   b  of the stacker section  40 . The pressure roller  49  is separated from the stacker lower guide  40   b  until the lead end of the paper sheet passes therethrough and is rotated so as to press the paper sheet against the stacker lower guide  40   b  after the leading end passes therethrough. The illustrated pressure roller  49  is provided at a substantial center in the sheet width direction. The pressure roller  49  is supported by a support arm  132  connected thereto on both sides thereof and is configured to be lifted or lowered by a spring clutch  134  wound between an intermediate shaft holder  136  and an arm holder  132   a  which are fixed to an intermediate shaft  135 . Turning of the intermediate shaft  135  is transmitted to the pressure roller  49  through a pressure roller transmission belt  133 , whereby the pressure roller  49  is driven. The turning drive of the intermediate shaft  135  is made by an intermediate transmission belt  137 , an intermediate gear  138 , a drive shaft  139  for driving the intermediate gear  138 , and a motor transmission belt  140  wounded between the drive shaft  139  and a pressure roller nip/separation motor  141  (M 9 ) for turning the drive shaft  139 . 
     When passing of the leading end of the paper sheet through the pressure roller  49  is detected in the stacker section and, then, the pressure roller nip/separation motor  141  is forward rotated by a stacker section storage operation controller  200 , the intermediate shaft holder  136  is rotated in the forward direction. The rotation in this direction loosen the spring clutch  134  to cause the arm holder  132   a  to be released from regulation, with the result that the pressure roller  49  is brought into pressure contact with the paper sheet by its own weight. While the pressure roller  49  is brought into pressure contact with the paper sheet, a torque for feeding the paper sheet to the downstream side is applied to the paper sheet, whereby the paper sheet is conveyed toward the illustrated stopper section  90 . 
     On the other hand, when the paper sheet entering the stacker section  40  is aligned or when the paper sheet is conveyed to the upstream side (e.g., in the switchback conveying direction toward the retreat path  47 ), the pressure roller nip/separation motor  141  is backward rotated to tighten the spring clutch  134  to lift the pressure roller  49 . Even when the pressure roller nip/separation motor  141  is stopped in this state, the pressure roller  49  is retained at a retreat position separated from the paper sheet by the motor torque and spring clutch. The pressure roller  49  may be lifted and lowered by a solenoid or the like directly connected thereto. 
     [Stopper Section Gripper Opening/Closing Mechanism] 
     With reference to  FIGS. 11A and 11B , a closing state where the gripper  91  positioned at a leading end of the stopper section  90  grips the paper sheet and an opening state where the gripping of the paper sheet by the gripper  91  is released will be described. The vertical movement of the stopper section  90  has already been described, so description thereof will be omitted here. 
       FIG. 11A  illustrates the entire moving range of the gripper  91 , in which the gripper  91  at the uppermost and lowermost positions is denoted by a virtual line.  FIG. 11B  is a plan view illustrating the gripper  91  and stopper section  90  as viewed from above. The gripper  91  is disposed at the leading end of the stopper section  90 , and a moving piece  91   b  of the gripper  91  is separated from a fixed piece  91   a  of the stopper section  90 . A gripper connecting portion  152  connecting the moving pieces  91   b  is disposed below the stopper section  90  and a stopper section connecting portion  151  so as to be overlapped therewith and to freely advance and retreat with respect thereto. Further, a closing spring  91   c  constantly biasing the moving piece  91   b  in a closing direction is provided below the moving piece  91   b.    
     The gripper connecting portion  152  has a connecting arm  153  protruding rearward from the stopper section  90 . The connecting arm  153  has an opening hole. A turning bracket  154  supporting upper and lower portions of a turning bar  156  penetrating the opening hole of the connecting arm  153  is provided. The turning bracket  154  is turned in a direction denoted by an arrow of  FIG. 11B  about a turning support point  155 . The turning bracket  154  has a turning cam  157  having a bracket pressing surface  158 . The turning cam  157  is rotated by a gripper opening/closing motor  160  (M 11 ). When the bracket pressing surface  158  presses the turning bracket  154  with the rotation of the turning cam  157 , the turning bracket  154  swings about the turning support point  155 . With this swing, the turning bar  156  whose upper and lower portions are supported by the turning bracket  154  advances/retreats. Since the turning bar  156  penetrates the opening hole of the connecting arm  153 , the moving piece  91   b  at the leading end of the connecting arm  153  contacts and separates from the fixed piece  91   a  of the stopper section  90 . 
     Further, as illustrated in  FIG. 11A , the turning bar  156  is positioned in the vertical movement range of the stopper section  90 , so that even when the stopper section  90  is moved vertically, the above connecting arm  153  can make the moving piece  91   b  constituting the gripper  91  at any vertical position. Thus, the closing state where the gripper  91  grips the paper sheet by the turning of the gripper opening/closing motor  160  and opening state where the gripping of the paper sheet is released are realized by the stacker section storage controller  200 . As illustrated in  FIG. 11A , the stacker section  40  is disposed in an inclined manner, so that the turning bracket  154  is constantly brought into abutment against the turning cam  157 . The turning bracket  154  may be brought into abutment against the turning cam  157  by a spring or the like. 
     [Sheet Bundle Generation Operation by Bonding] 
     The following sequentially describes a generation operation of a paper sheet bundle obtained by applying the adhesive onto the paper sheet conveyed from the image forming device A by means of the adhesive application device  50  in the stacker section  40  and bonding the paper sheets to each other with reference to  FIGS. 12A to 19 . 
     First, in the image forming device, the paper sheets discharged from the main body discharge port  3  are aligned in a bundle, and then the “bonded paper sheet bundle folding mode” in which the paper sheets are bonded, folded in a booklet form, and stored on the second sheet discharge tray  22  is instructed. 
     Then, as illustrated in  FIG. 12A , a first paper sheet onto which an image has been formed is discharged from the main body discharge port  3  of the image forming device A, passed through the sheet carry-in path P 1  and first switchback conveying path SP 1  of the sheet processing device ( FIG. 2 ), and conveyed along the carry-in path  41  serving as the second switchback path SP 2  by means of the path carry-in roller  45  and conveying roller  46 . At this time, the stopper section  90  for regulating the leading end of the paper sheet to be carried into the stacker section  40  is moved from the illustrated initial home position Sh 0  to the sheet (bundle) rear end branching point passing position Sh 1  at which the rear end of the paper sheet whose leading end abutting with the stopper section  90  is situated at a branching position between the carry-in path  41  and retreat path  47  and stands by there. 
       FIG. 12B  illustrates a state where the rear end of the paper sheet carried into the stacker section  40  is situated at the above branching position. The paper sheet to be conveyed to this position is conveyed until it abuts against the stopper section  90  standing by at the sheet (bundle) rear end branching point passing position Sh 1 . During the conveyance, the paper sheet is conveyed with the sheet leading end pushing up the deflection guide  44  positioned near the exit of the carry-in path  41 . Thereafter, after the leading end of the paper sheet passes through the pressure roller  49 , the pressure roller  49  is moved to a position pressing the paper sheet so as to convey the paper sheet to the stopper section  90 . The gripper  91  disposed at the leading end of the stopper section  90  is situated at a position at which the gripping of the paper sheet is released so as to receive the paper sheet in a state where the moving piece  91   b  is separated from the fixed piece  91   a . At a time point when the leading end of the paper sheet abuts against the stopper section  90 , the rear end of the paper sheet is situated at the branching position and directed to the retreat path  47  constituting the third switchback path SP 3  by the deflection guide  44 . 
       FIG. 13A  illustrates a state where the stopper section  90  gripping the paper sheet by means of the gripper  91  at a time point when the rear end of the sheet passes through the branching position is moved up. In this case, the rear end of the paper sheet is directed to the retreat path  47  by the deflection guide  44 , so that the paper sheet is switchback-conveyed along the retreat path. At this time, a second paper sheet is carried into the sheet carry-in path P 1 . 
       FIG. 13B  illustrates a state where the movement of the first paper sheet by the stopper section  90  is stopped at the adhesive tape transfer position Sh 3  at which a half position of the paper sheet in the sheet conveying direction is situated at the application position (sheet pressing position of the adhesive tape stamper  51 ) of the adhesive application device  50 . At this timing, the width direction side edges of the paper sheets in a stopped state are tapped by the sheet side edge aligning member  48  disposed adjacent to the adhesive application device  50  for position alignment. After completion of the alignment operation, the cam moving motor  60  of the adhesive application device  50  is driven to move each adhesive tape stamper toward the paper sheet. Then, the paper sheet is pressed first by the sheet presser  65  and then by the sheet pressing slider  71 . After that, the transfer head  72  is pressed against the paper sheet to apply the adhesive on the adhesive tape AT onto the paper sheet. After the application, the above members pressing the paper sheet are separated from the paper sheet. During the application, the gripper  91  grips the leading end of the paper sheet. 
       FIG. 14A  illustrates a state where the stopper section  90  is moved, after separation of the transfer head  72 , sheet pressing slider  71 , and sheet presser  65  from the paper sheet, to the adhesive tape concealing position (next sheet receiving position) Sh 4  at which the adhesive-applied portion of the paper sheet is retreated to the retreat path  47  so as to prevent the adhesive-applied position from interfering with conveyance of the next paper sheet. The application position is subjected to switchback conveyance by about 35 mm from the above bonding position and thus situated in the retreat path (position  100  in the drawing). The above moving distance is desirably set as small as possible so as not to allow the adhesive-applied position to be adhered to the conveying guide or deflection guide  44 . Further, a member contacting the paper sheet, such as the deflection guide  44 , is disposed between adhesive lines. After movement of the application position of the preceding paper sheet to the retreat position (position  100  in the drawing), the moving piece  91   b  is separated from the fixed piece  91   a  so as to release the gripping of the paper sheet by the gripper  91  which grips the paper sheet during the application and movement of the application position. 
     In a state where the gripping state of the paper sheet by the gripper  91  is released, a next paper sheet is moved along the carry-in path  41  as illustrated in  FIG. 14B  to be carried into the stacker section  40 . In this state, the application position of the preceding paper sheet is retreated to the retreat path and concealed, so that the next paper sheet can be carried in on the preceding paper sheet without any trouble. The stopper section  90  stands by for carry-in of the next paper sheet at the adhesive tape concealing position (next sheet receiving position/position  100  in the drawing) Sh 4 . 
       FIG. 15A  illustrates a state where the stopper section  90  receives the leading end of the next paper sheet at the adhesive tape concealing position (next sheet receiving position/position  100  in the drawing) Sh 4 . In this state, the rear end of the preceding paper sheet (including the application position thereof) is situated in the retreat path  47 , and rear end of the next paper sheet is situated in the carry-in path  41 . Further, the leading ends of both the preceding and next paper sheets abut against the stopper section  90 . The pressure roller  49  is lowered so as to be brought into pressure contact with the next paper sheet when the leading end of the next paper sheet passes through the pressure roller  49  and applies a conveying force to the next paper sheet. After the preceding and next paper sheets abut against the stopper section  90 , the sheet side edge aligning member  48  is activated so as to align both the paper sheets. Prior to this alignment operation, nipping of the conveying roller  46  positioned in the carry-in path  41  is released, and the pressure roller  49  is separated from the paper sheet. Thereafter, the side edges of both the paper sheets overlapped with each other with the rear ends thereof positioned in the different paths (carry-in path  41  and retreat path  47 ) are pressed by the sheet side edge aligning member  48  for alignment. In the present embodiment, the pressing is performed twice. During the alignment operation, the gripper  91  is in an opened state where the gripping of the paper sheet is released. 
     As illustrated in  FIG. 15B , after the above alignment operation, the conveying roller  46  in the carry-in path  41  is made to nip the paper sheets, and the pressure roller  49  is pressed against the paper sheets. Further, the gripper  91  is made to grip the paper sheets. In this state, the stopper section  90  is moved down to the sheet (bundle) rear end branching point passing position Sh 1  at which the rear end of the second (next) paper sheet passes through the branching position. With this operation, the adhesive-applied position of the first (preceding) paper sheet passes through the pressure roller  49 , and thus the bonding to the next sheet is achieved to some extent. At this time, a third paper sheet is being carried into the sheet carry-in path P 1 . 
       FIG. 16A  illustrates a state where the stopper section  90  is moved up from the sheet (bundle) rear end branching point passing position Sh 1  to adhesive tape transfer position Sh 3 . At a start timing of the movement, the rear end of the second (next) paper sheet is biased toward the retreat path  47  by the deflection guide  44  and is therefore switchback-conveyed along the retreat path  47  in a bundle with the first (preceding) paper sheet. As described above, the Sh 3  is a position at which the adhesive tape stamper  51  of the adhesive application device  50  presses the transfer tape AT against the half position of the second (next) paper sheet in the sheet conveying direction for application of the adhesive. The adhesive application device  50  is activated to apply the adhesive onto the next paper sheet and, at the same time, the next and preceding paper sheets are pressed against each other for bonding. At this position, in particular, the transfer head  72  presses the position at which the adhesive has been applied, so that the paper sheets are reliably boded to each other. At this time, a leading end of the third paper sheet is entering the carry-in path  41 . 
       FIG. 16B  illustrates a state where the stopper section  90  is moved down to the adhesive tape concealing position (next sheet receiving position/position  100  in the drawing) Sh 4  so as to carry in the adhesive-applied positions of the respective first and second paper sheets that have been bonded to each other into the retreat path  47 , and carry-in of the third paper sheet is waited for. The gripper  91  of the stopper section  90  grips the paper sheets during movement of the paper sheet bundle and application of the adhesive, but releases the gripping of the paper sheets when the next paper sheet is received.  FIG. 16B  illustrates the same state as that illustrated in  FIG. 14B . Afterward, processes from  FIG. 14B  to  FIG. 16B  are repeated until the second to last paper sheet constituting the paper sheet bundle is carried in. 
     In the present embodiment, it is assumed that the third paper sheet is the last paper sheet constituting the paper sheet bundle. 
       FIG. 17A  illustrates a state where the adhesive-applied position of the second paper sheet is situated in the retreat path  47  and where the third paper sheet as the last paper sheet constituting the paper sheet bundle is carried in and abuts its leading end against the stopper section  90 . In this state, the sheet side edge aligning member  48  is activated to press the side edges of the third sheet paper and first and second paper sheets a part of each of which is situated in the retreat path  47  for alignment. For this alignment operation, release of the nipping of the conveying roller  46 , retreat of the pressure roller  49  from the sheet pressing position, and release of the gripping of the paper sheet by the gripper  91  are performed in the same manner as for the alignment operation between the first and second paper sheets. Thus, the rear ends of the first and second paper sheets are positioned in the retreat path  47 , and the rear end of the third paper sheet is positioned in the carry-in path. In this state, the alignment operation is performed with the leading ends of the first to third paper sheets overlapped with each other. 
     In a state illustrated in  FIG. 17B , the nipping of the conveying roller  46 , movement of the pressure roller  49  to the sheet pressing position, and the gripping of the paper sheet by the gripper  91  are performed after completion of the above alignment operation, and then the stopper section  90  is moved down to a position (in the present embodiment, this position is set to a position upstream of the adhesive tape transfer position Sh 3  by about 5 mm since the paper sheet is pressed by the sheet pressing slider  71  positioned upstream of the transfer head  72 : position Z in  FIG. 2 ) near the adhesive tape transfer position Sh 3 . This is because the adhesive need not be applied to the last paper sheet, so that the paper sheet is pressed not at the bonding position corresponding to the transfer head  72  but at a position at which only the paper sheet is pressed for bonding between the paper sheets. 
       FIG. 18A  illustrates a state where after completion of bonding of the last third paper sheet to the preceding first and second paper sheets, the third paper sheet is moved down, while being gripped by the gripper  91  of the stopper section  90 , to the sheet (bundle) rear end branching point passing position Sh 1  at which the rear end of the third paper sheet exceeds downward the branching point between the carry-in path  41  and retreat path  47 . In this state, the first to third paper sheets are press-bonded to each other also by the pressure roller  49  which has been already situated at the sheet pressing position, thereby further securing adhesion between the paper sheets. 
       FIG. 18B  illustrates a state where the stopper section  90  is moved up from the sheet (bundle) rear end branching point passing position Sh 1  toward the bonded bundle folding position Sh 2  while the paper sheets are being gripped by the gripper  91 . With this movement, an upstream end of the paper sheet bundle is carried into the retreat path  47  by the deflection guide  44 , and all the three paper sheets are switchback-conveyed. 
       FIG. 19  illustrates a state where the stopper section  90  is situated at the bonded bundle folding position Sh 2 . In this state, the movement of the sheet bundle is stopped, the gripping of the paper sheets by the gripper  91  is released, and then folding processing is performed using the folding roller  81  and folding blade  68 . This folding blade  86  also presses the adhesive-applied position to further strengthen adhesion between the paper sheets. 
     As illustrated in  FIGS. 17A to 19 , for the last paper sheet, the stopper section  90  as the moving member is moved in the order of the adhesive tape concealing position Sh 4 →position 5 mm upstream of the adhesive tape transfer position Sh 3 →sheet rear end branching point passing position Sh 1 →bonded bundle folding position Sh 2 . That is, before being moved to the folding position Sh 2 , the paper sheets are subjected to pressing at a plurality of points (sheet pressing slider  71  and pressure roller  49 ), thereby strengthen adhesion between the paper sheets. 
     The above conveying order may be changed depending on a type of the adhesive to be used or type of the paper sheets to be bound. For example, as a second conveying order of the last paper sheet, an order of Sh 4 →Sh 1 →Sh 3  −5 mm→Sh 2  may be adopted. According to the second conveying order, the paper sheets are pressed first by the pressure roller  49  and then by the sheet pressing slider  71 . 
     Further, as a third conveying order of the last paper sheet, an order of Sh 4 →Sh 1 →Sh 2  may be adopted. According to the third conveying order, the paper sheets are pressed by the pressure roller  49 , and the subsequent pressing by the sheet pressing slider  71  is omitted. 
     When an order of Sh 4 →Sh 3  −5 mm→Sh 2  is adopted so as to allow the paper sheets to the bonded bundle folding position Sh 2  earlier, the paper sheets can be subjected to the folding processing after being pressed by the sheet pressing slider  71 . In this case, the folding processing is performed with the rear end of the third paper sheet positioned in the carry-in path  41  and the rear ends of first and second paper sheets positioned in the retreat path  47 . In the above respective examples, the “Sh 3  −5 mm” is a position of the sheet pressing slider  71  5 mm upstream of the adhesive tape transfer position, at which the adhesive-applied positions of the respective paper sheets other than the last paper sheet are stopped so as to be pressed by the sheet pressing slider  71  for bonding. This “Sh 3  −5 mm” position may appropriately be change as long as the last paper sheet applied with no adhesive and preceding paper sheets can be pressed together for bonding at the adhesive-applied position of the preceding paper sheets. 
     The following describes more in detail the pressing operation of the sheet pressing slider  71  for bonding the last paper sheet and preceding bonded paper sheets using  FIGS. 21A to 21C  and  FIGS. 22A and 22B .  FIGS. 21A to 21C  are explanatory view illustrating a relationship between the sheet pressing slider  71  illustrated in  FIGS. 3, 4, 6A to 6D  and platen  79 . 
       FIGS. 22A and 22B  each illustrate a modification of the pressing mechanism of the sheet pressing slider.  FIG. 22A  illustrates a mechanism that uses a pressure roller as a sheet pressing member, and  FIG. 22B  illustrates a mechanism that uses a pair of rollers as a sheet pressing member. 
       FIG. 21A  is a bottom view of the sheet pressing slider  71 . As illustrated in  FIG. 21A , the sheet pressing slider  71  includes a pressing portion  170  having a substantially quadrangular shape and configured to press a comparatively wide area of the paper sheet, side pressing portions  171  extending from both sides of the pressing portion  170 , and a leading end pressing portion  172  connecting leading sides of the side pressing portions  171 . Inside the above pressing portions, the transfer head  72  supporting the adhesive tape AT is positioned. A symbol X in the drawing denotes a center position of the adhesive tape AT, and the adhesive of the adhesive tape is applied onto the paper sheet with the position X as a center. A symbol Z denotes a sheet pressing position at which the adhesive-applied positions of the paper sheets preceding a last paper sheet to be described later are subjected to pressing. 
       FIG. 21B  illustrates a state where the adhesive of the adhesive tape AT is applied onto the newly conveyed and positioned third paper sheet. That is, first the paper sheets are pressed against the platen by the sheet pressing slider  71 . Then, with the movement of the sheet pressing slider  71 , a new adhesive surface of the adhesive tape AT is exposed, and the transfer head  72  is pressed against the paper sheet on the platen  79 . As a result, the adhesive of the adhesive tape AT is applied onto the new third paper sheet, and preceding first and second paper sheets and third paper sheet are bonded to each other at the adhesive-applied position. After completion of the adhesive application and paper sheet bonding, the transfer head  72  and sheet pressing slider  71  are separated from the paper sheet as illustrated. 
     The above adhesive application and paper sheet bonding are repeated up to carry-in of the second to last paper sheet. The adhesive application and paper sheet bonding are performed for each carry-in of the paper sheet, and the carried-in paper sheets are bound together. 
       FIG. 21C  illustrates a position of the sheet pressing slider  71  with respect to the last paper sheet (in this example, fourth paper sheet). As described above, the last fourth paper sheet is applied with no adhesive, and fourth paper sheet and the preceding first to third paper sheets are pressed together for bonding. At the bonding position X for the preceding first to third paper sheets, the transfer head  72  is pressed against the paper sheet. To avoid this, the adhesive application position is set at a position 5 mm upstream of the bonding position X in the present embodiment. At this position, the paper sheets are pressed between the pressing portion  170  having a comparatively wide pressing area and platen  79 . With this pressing, the last fourth paper sheet is pressed against the adhesive-applied on the preceding third paper sheet and bonded thereto. 
     The platen  79  includes a platen guide portion  176  for guiding conveyance of the paper sheet from the upstream side, a last sheet pressing portion  175 , and a platen cushioning portion  174  positioned facing the transfer head  72  and applied with a slightly elastic sheet for backup of the adhesive application and paper sheet bonding. With this configuration, the paper sheets are reliably bonded to each other. 
       FIGS. 22A and 22B  each illustrate a modification of the pressing mechanism of the sheet pressing slider  71 .  FIG. 22A  illustrates a mechanism that uses a pressure roller  177  as a sheet pressing member. The pressure roller  177  is provided at a position facing a downstream extended portion of the platen  79  and is configured to be movable between a position facing a downstream extended portion of the platen  79  and is moved, by a not illustrated mechanism, between a position pressing the last paper sheet (in this example, all the paper sheets including the fourth paper sheet; the same applies to the following) against the platen and a position separated therefrom. In this modification, a sheet pressing position Z for the last paper sheet is positioned downstream of the bonding position X.  FIG. 22B  illustrates a mechanism in which a backup roller  178  as a member for pressing the last paper sheet is disposed opposite to the pressure roller  177 . That is, bonding of the last paper sheet is performed by the roller pair. By pressing the last paper sheet using both the pressing portion  170  of the sheet pressing slider  71  and pressure roller  177  in the above mechanisms, the paper sheets can be bonded to each other more reliably. 
     [Mechanism and Operation of Folding Section] 
     The following describes a configuration of the folding section  80  that applies folding processing to the bonded bundle at the bonded bundle folding position Sh 2 . As illustrated in  FIG. 20A , there are provided, at the folding position Y disposed downstream of the adhesive application device  50 , a folding roller  81  for folding the bonded paper sheet bundle and a folding blade  86  for inserting the paper sheet bundle into a nip position of the folding roller  81 . The folding roller  81  is constituted by rollers  81   a  and  81   b  brought into pressure contact with each other. The rollers  81   a  and  81   b  are each formed to have a length substantially corresponding to the maximum width of the paper sheet. Rotary shafts of the respective rollers  81   a  and  81   b  constituting the folding roller  81  are fitted respectively into long grooves of a not illustrated device frame and are biased in a pressure-contact direction by respective compression springs  81   a S and  81   b S so as to allow the rollers  81   a  and  81   b  to be brought into pressure contact and coupled with each other. The folding roller may have a structure in which at least one of the rollers  81   a  and  81   b  is axially supported so as to be movable to the pressure-contact direction and is provided with the compression spring. 
     The pair of rollers  81   a  and  81   b  are each formed of a material, such as a rubber, having a large friction coefficient. This is for conveying the paper sheet bundle in a roller rotation direction while folding the same by a soft material such as a rubber, and the rollers  81   a  and  81   b  may be formed by applying lining to a rubber material. 
     The following describes an operation of folding the paper sheet bundle by means of the above folding roller  81  with reference to  FIGS. 20A to 20D . The pair of rollers  81   a  and  81   b  are positioned above the stacker section  40  and below the adhesive application device  50 , and the folding blade  86  having a knife edge is provided at a position facing the roller pair  81   a  and  81   b  with the bonded paper sheet bundle supported by the stacker section  40  interposed therebetween. The folding blade  86  is supported by a device frame so as to be reciprocatable between a standby position illustrated in  FIG. 20A  and a nip position illustrated in  FIG. 20C . 
     The paper sheet bundle supported in a bundle in the stacker section  45  is stopped by the stopper section  90  in a state illustrated in  FIG. 20A , and the folding position of the paper sheet bundle, to which the adhesive is applied by the adhesive tape stampers  51 , is positioned at the folding position. Upon acquisition of a set completion signal of the paper sheet bundle, a drive controller (“sheet folding operation controller  202 ”; the same applies to the following) turns off a clutch. 
     The sheet folding operation controller  202  moves the folding blade  86  from the standby position to nip position at a predetermined speed. Then, as illustrated in  FIG. 20B , the paper sheet bundle is bent by the folding blade  86  at the folded position and is inserted between the rollers  81   a  and  81   b . At this time, the pair of rollers  81   a  and  81   b  are driven into rotation along with the movement of the paper sheet bundle by the folding blade  86 . Then, the sheet folding operation controller  202  stops a blade drive motor (not illustrated) after elapse of an estimated time period during which the paper sheet bundle reaches a predetermined nip position to stop the folding blade  86  at a position illustrated in  FIG. 20C . Around this time, the sheet folding operation controller  202  turns ON the not illustrated clutch to drive the folding roller  81  into rotation. Then, the paper sheet bundle is fed in a delivery direction (leftward in  FIG. 20C ). Thereafter, as illustrated in  FIG. 20D , the sheet folding operation controller  202  moves the folding blade  86  positioned at the nip position toward the standby position concurrently with the delivery of the paper sheet bundle by the folding roller  81 . 
     When the thus folded paper sheet bundle is pushed between the folding rollers  81   a  and  81   b , an outermost paper sheet contacting a roller surface is not drawn completely between the rotating rollers. That is, the folding roller  81  is rotated following the movement of the inserted (pushed) paper sheet bundle, preventing only the paper sheet contacting the roller from being caught between the rollers prior to the other paper sheets. Further, since the roller is rotated following the movement of the inserted paper sheet bundle, the roller surface and the outermost paper sheet contacting the roller surface are not rubbed with each other, so that image rubbing-off does not occur. 
     Referring back to  FIG. 2 , a sheet transfer path (hereinafter, referred to merely as “transfer path”) for guiding the sheet bundle folded in a booklet form to the second sheet discharge tray  22  for storage is provided downstream of the folding roller  81 , and the paper sheet bundle folded in two into a booklet by the folding roller  81  is carried out to the second sheet discharge tray  22  by the bundle discharge roller  95  provided at an exit of the transfer path and having the bundle kick-out piece. The discharged paper sheet bundle is stored on the second sheet discharge tray  22  by the bundle press guide  96  and bundle presser  97  for preventing expansion of the folded paper sheet bundle. 
     [Control Configuration] 
     The following describes a system control configuration for the above-described image forming device with reference to a block diagram of  FIG. 23 . The system for the image forming device illustrated in  FIG. 1  includes an image forming device controller  180  for the image forming device A and a sheet processing controller  191  for the sheet processing device B. The image forming device controller  180  includes an image forming controller  181 , a sheet supply controller  186 , and an input section  183 . A user sets “image forming mode” or “sheet processing mode” through a control panel  18  provided in the input section  183 . As described above, in the image forming mode, the image forming conditions such as a print copy count specification, a sheet size specification, a color or black-and-white printing specification, enlarged or reduced printing specification, a single- or double-side printing specification are set. Then, the image forming device controller  180  controls the image forming controller and sheet supply controller according to the set image forming conditions to form an image onto a predetermined paper sheet and carries out the resultant paper sheet through the main body discharge port  3 . 
     At the same time, the user sets the sheet processing mode through the control panel  18 . The sheet processing mode includes, e.g., a “print-out mode”, a “staple-binding mode”, and a “bonded sheet bundle folding mode”. The image forming device controller  180  transfers the set sheet processing mode, the number of paper sheets, copy number information, and binding or bonding mode (binding at one or a plurality of positions) information to the sheet processing controller  191 . 
     The sheet processing controller  191  includes a control CPU  192  that operates the sheet processing device B in accordance with the specified finishing mode, a ROM  193  that stores an operation program, and a RAM  194  that stores control data. The control CPU  192  includes a sheet conveying controller  195  that executes conveyance of the paper sheet fed to the carry-in port  23 , a sheet punch controller  196  that uses a punch unit  28  to perform punch operation for the paper sheet, a processing tray storage operation controller  197  that uses the processing tray  29  to perform sheet storage operation, a processing tray discharge operation controller  198  that discharges the paper sheet bundle from the processing tray  29 , and a first sheet discharge tray sheet loading operation controller  199  that moved vertically the first sheet discharge tray  21  in accordance with a storage amount of the paper sheets or paper sheet bundle discharged from the processing tray. 
     The sheet processing controller  191  further includes a stacker section storage operation controller  200  for controlling bonding and folding operations while storing the paper sheets in the stacker section  40 , a sheet binding/bonding operation controller  201  for instructing a sheet bonding operation, and a sheet folding operation controller  202  for folding the paper sheet bundle bonded with adhesive in two. The sheet binding/bonding operation controller  201  also controls the end surface stapler  35  that binds the paper sheets stored on the processing tray  29  using a staple. Although not illustrated, the above controllers each receive a position signal from a sensor that detects a position of the sheet conveying path or each member. 
     A connection between the controllers and motors will be described using  FIG. 23 . The sheet conveying controller  195  is connected to a control circuit of a drive motor M 1  so as to control drive of the carry-in roller  24  and the like that receive the paper sheet from the image forming device A and conveys it. The sheet conveying controller  195  once switchback-conveys the paper sheet to the second switchback path SP 2  to put the paper sheet on standby therein when carrying in the paper sheet to the processing tray  29  and then discharges the paper sheet together with a next paper sheet. This is done so as to continue a series of processing without stopping the operation on the image forming device A side. The sheet conveying controller  195  controls the drive motor M 2  that can forward/backward rotate the path carry-in roller  45  in the carry-in path  41  so as to enable the switchback conveyance. The sheet conveying controller  195  also controls a separating motor  131  (M 3 ) that separates the pinch roller  125  from the drive roller  120  when paper sheet alignment is performed with the leading end of the paper sheet positioned in the stacker section  40  and rear end thereof positioned in the carry-in path  41 . 
     The sheet punch controller  196  is connected to a control circuit of a punch motor M 4  so as to punch a punch hole in the paper sheet. 
     The processing tray storage operation controller  197  is connected to a control circuit of a nip/separation motor M 5  that nips and separates the sheet discharge roller  25  so as to carry in the paper sheet to the processing tray  29  or first sheet discharge tray  21  or carry out the paper sheet from the processing tray  29 . The processing tray storage operation controller  197  is also connected to a control circuit of a side aligning plate motor M 6  that reciprocates the side aligning plate  36  in the sheet width direction so as to align the paper sheets on the processing tray  29 . 
     The processing tray discharge operation controller  198  is connected to a control circuit of a bundle discharge motor M 7  that moves the rear end regulating member  33  toward the sheet discharge port  25   a  so as to discharge, to the first sheet discharge tray, the paper sheet bundle whose end portion is bound with the end surface stapler  35  in the processing tray  29 . A control circuit of a first tray elevating motor M 8  that elevates the first sheet discharge tray  21  in accordance with an amount of paper sheets stored therein is connected to the first sheet discharge tray sheet loading operation controller  199  and controlled thereby. 
     The controllers for applying the adhesive onto the half position of the paper sheet in the sheet conveying direction to bond the paper sheets to each other and folding the bonded paper sheets at the adhesive-applied position will be described using  FIG. 23 . The stacker section storage operation controller  200  is connected to a control circuit of a pressure roller nip/separation motor  141  (M 9 ) so as to move, to the sheet pressing position, the pressure roller  49  positioned about the middle of the stacker section  40  and configured to convey downstream the paper sheet carried into the stacker section  40  while pressing the paper sheet, to drive the pressure roller  49  into rotation, and to backward rotate the pressure roller  49  to separate the same from the paper sheet. 
     The stacker section storage operation controller  200  is further connected to a control circuit of a stopper section  90  moving motor M 10  so as to move the stopper section  90  to move the paper sheet entering the stacker section  40  between the initial home position Sh 0 , the sheet (bundle) rear end branching point passing position Sh 1  at which the rear end of the paper sheet is situated at the branching position between the carry-in path  41  and retreat path  47 , bonded bundle folding position Sh 2  at which the bonded paper sheet bundle is folded in two, adhesive tape transfer position Sh 3  at which the preceding paper sheet is switchback-conveyed to the retreat path  47  so as to prevent the adhesive-applied onto the preceding paper sheet from being adhered to the next paper sheet to be carried into the stacker section  40  from the carry-in path  41 . The movement of the paper sheet between the above positions is as described above in detail using  FIGS. 12A to 19 . 
     The stacker section storage operation controller  200  is further connected to a control circuit of a gripper opening/closing motor  160  (M 11 ) so as to grip the leading end of the paper sheet at the leading end of the stopper section  90  and release its gripping. The timing of the gripping operation of the gripper has already been described, so description thereof is omitted. The stacker section storage operation controller  200  is further connected to a control circuit of an aligning motor  117  (M 12 ) that reciprocates, in the sheet width direction, the sheet side edge aligning member  48  that can align even the paper sheets whose leading ends are positioned at the same position (stacker section  40 ), while whose rear ends are positioned at different positions (carry-in path  41  and retreat path  47 ). 
     The sheet binding/bonding operation controller  201  is connected to a control circuit of a cam moving motor  60  (M 13 ) that reciprocates the cam member  57  between a position that presses the adhesive tape stampers  51  of the adhesive application device  50  against the paper sheet to apply the adhesive and a position separated from the paper sheet. The sheet binding/bonding operation controller  201  is connected to the end surface stapler  35  of the processing tray  29 . 
     As already described, the sheet folding operation controller  202  is configured to rotate or reciprocate the folding blade  86 , folding rollers  81   a ,  81   b , and bundle discharge roller  95  by means of a common motor and is connected to a drive circuit so as to control a drive motor M 15 . 
     The controller configured as described above controls the sheet processing device to execute the following operation modes. 
     “Printout Mode” In this mode, the paper sheets each on which an image has been formed in the image forming device A are sequentially conveyed to the first sheet discharge tray  21  through the sheet carry-in path P 1  and sequentially stacked upward in facedown in the order from the first page to n-th page.
 
“Staple Binding Mode”
 
     In this mode, the image forming device A performs image formation on a series of pages from the first page to n-th page and sequentially carries out in facedown the resultant pages from the main body discharge port  3 , as in the printout mode. After being conveyed to the sheet carry-in path P 1 , each of the paper sheets are switchback-conveyed along the first switchback conveying path SP 1  onto the processing tray  29 . By repeating this sheet conveying operation, a series of the paper sheets are stored in facedown on the first processing tray  29  in a bundled state. After the paper sheet bundle is stored, the end surface stapler  35  is activated to staple-bind the rear end edge of the paper sheet bundle staked on the tray. After that, the staple-bound paper sheet bundle is carried out to and stored on the first sheet discharge tray  21 . As a result, a series of the paper sheets each on which the image has been formed in the image forming device A are staple-bound and stored on the first sheet discharge tray  21 . 
     “Bonded Paper Sheet Bundle Folding Mode” 
     In this mode, in the sheet processing device B, the paper sheets are applied with the adhesive and then bonded together in a booklet form. To this end, the paper sheet conveyed to the sheet carry-in path P 1  is guided to the second switchback conveying path P 1  and then to the stacker section  40  by the path carry-in roller  45  and conveying roller  46 . 
     The subsequent flow of the paper sheet, paper sheet bonding operation, and relationship between the preceding and next paper sheet have been already described, so descriptions thereof are omitted. The features of the present embodiment are as follows. 
     1. Operation in which the preceding paper sheet is retreated to the retreat path  47  after applied with the adhesive so as to prevent the adhesive from being adhered to the next paper sheet is repeated until completion of the paper sheet bundle formation. 
     2. The adhesive application device  50  applies the adhesive onto the paper sheet and presses this paper sheet against the preceding paper sheet that has already applied with the adhesive to form the paper sheet bundle. This operation is repeated until completion of the paper sheet bundle formation.
 
3. The paper sheets are aligned by the sheet side edge aligning member  48  before application of the adhesive with the rear ends thereof positioned in the carry-in path  41  and retreat path  47 , respectively, and leading ends abutting against the stopper section  90 .
 
4. The above adhesive application by the adhesive application device  50  and paper sheet movement by the stopper section  90  are performed with the leading end of the paper sheet gripped by the gripper  91 . On the other hand, when the paper sheets are aligned, or when the next paper sheet to be conveyed to the stopper section  90  is received, the gripping is released.
 
5. The adhesive application device  50  groups the adhesive tape stampers  51  and presses the adhesive against the paper sheet in units of the group for adhesive application.
 
6. The adhesive tape stamper  51  is pressed for a certain time so that a constant pressing force is applied by the spring force of the pressure spring  62 .
 
7. The adhesive application device  50  uses the sheet presser  65  to press the paper sheet before application of the adhesive onto the paper sheet so as to prevent displacement or flapping of the paper sheet.
 
8. A part of the sheet conveying path or retreat path is incorporated in the adhesive application device  50  as a unit, and this adhesive application device  50  is incorporated in the stacker section  40  of the sheet processing device B. With this configuration, displacement between the paper sheet and each member caused due to the movement of the paper sheet can be reduced.
 
9. For the last paper sheet, the adhesive application is not performed, and the pressing position is shifted to the upstream side so as to secure the adhesion to the preceding paper sheet.
 
     After the adhesive application and bundle generation operations are performed in the stacker section under the above control, the generated paper sheet bundle is subjected to folding and then carried out to the second sheet discharge tray  22 .