Patent Publication Number: US-10759135-B2

Title: Binding unit, sheet processing device, and image forming device provided with them

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This is a continuation application of Ser. No. 15/990,031 filed on May 25, 2018, which claims priorities of Japanese Patent Applications No. 2017-104476 filed on May 26, 2017, No. 2017-104477 filed on May 26, 2017, No. 2017-104478 filed on May 26, 2017, No. 2017-128935 filed on Jun. 30, 2017 and No. 2017-128936 fled on Jun. 30, 2017, the disclosures of which are incorporated herein as references. 
    
    
     BACKGROUND OF THE INVENTION 
     Field of the Invention 
     The present invention relates to a binding unit that applies binding processing to sheets, a sheet processing device, and an image forming device provided with them and, more particularly, to a binding unit or a sheet processing device that crimps and binds placed sheets after applying water to the sheet crimping range. 
     Description of the Related Art 
     Conventionally, an image forming device such as a copier, a printer, a facsimile device, and a compound machine thereof includes a sheet processing device. The sheet processing device has a binding unit that applies binding processing to a sheet bundle constituted by image-formed sheets placed onto a processing tray. 
     As such a binding unit, there is known a binding unit that crimps and binds sheets without use of a metal stapler needle that operates as a binding member for energy saving and environmental protection. In this so-called crimp-binding, a load is applied to a pair of pressure teeth each provided with projections and recesses with overlapped sheets interposed therebetween such that the projections and recesses mate with each other. As a result, fibers of the sheets are entangled with each other, whereby the sheets are fixedly bound together. 
     In this crimp-binding, the sheets can be bound without use of the staple needle; however, when the number of sheets to be bound is increased, the projections and recesses of the pressure teeth become less liable to mate with each other, with the result that fastening force between the pressure teeth is weakened. 
     For the purpose of increasing the fastening force, in Patent Document 1, a block of water is applied to the surface of a sheet bundle when the sheet bundle is crimped using an upper die (upper pressure teeth) having triangular projections and recesses and a lower die (lower pressure teeth) mating with the upper die (FIG. 1 of Patent Document 1). That is, when water is permeated into a sheet made of a paper material, fibers of the sheet are unfolded and become easy to be entangled with each other, resulting in an increase in bonding power among fibers. 
     Similarly, Patent Document 2 discloses a device that applies water to paper sheets before crimping the paper sheets so as to facilitate mutual entanglement of the fibers of the sheets. In this device, the water is fed along the edge of the sheet during conveyance of the sheet, so that the water can be fed to each sheet being conveyed (FIG. 2 of Patent Document 2). 
     Furthermore, Patent Document 3 discloses a device that applies water to a sheet binding area before performing crimp-binding. In this device, an inkjet head that ejects water from a nozzle hole is used as a water application means (FIG. 10 of Patent Document 3). Further, the disclosed device is configured to change crimping strength by changing the amount of water to be applied. 
     Further, in the device disclosed in Patent Document 4, crimping is done with masking performed to limit the water application range (particularly, FIG. 10 of Patent Document 4). When water is fed along the sheet edge as in the technique disclosed in Patent Document 2, the part of the sheet that is not subjected to crimp-binding becomes shabby due to the water feeding along the edge of the sheet, and thus finishing quality of the bound sheet bundle is deteriorated. Thus, the masking is performed so as to prevent this problem.
     [Patent Document 1] Japanese Patent Gazette No. 3481300   [Patent Document 2] Japanese Patent Gazette No. 3502204   [Patent Document 3] Japanese Patent Application Publication No. 2014-201432   [Patent Document 4] Japanese Patent Application Publication No. 2017-013930   

     However, in Patent Document 1, water is fed from a tank through one water hole formed in the pressure teeth to form a block of water on the sheet surface by surface tension. This is not sufficient to permeate water into the sheet to such a degree that the fibers are unfolded. 
     Further, in Patent Document 2, water is applied to each sheet by a fabric-like belt. Like Patent Document 1, water is hardly permeated into the sheet to such a degree that fibers are unfolded. 
     In Patent Document 3, the inkjet head is used to apply water to a crimp-binding range. However, water needs to be applied to each sheet, and water still cannot be permeated sufficiently. In addition, in Patent Document 3, the inkjet head for water application needs to be moved to a sheet bundle and retracted therefrom, thus complicating the device configuration. 
     Further, in Patent Document 4, the inkjet head is used to apply water with masking performed to limit the water application range, and then crimping is performed. Thus, like Patent Document 4, water cannot be permeated into the sheet sufficiently, and the inkjet head needs to be moved to a sheet bundle and retracted therefrom. 
     SUMMARY OF THE INVENTION 
     The object of the present invention is to facilitate permeation of water when water is applied to the crimping range of a sheet made of a water-permeable paper material. 
     The present invention has the following configuration. 
     A binding unit is a unit that applies water to placed sheets and then crimp-binds the sheets, the unit including a pair of pressurizing parts provided on both the front and back sides of the sheets and configured to crimp-binding the sheets, a water reservoir provided on the back surface side of either one of the pressurizing parts and configured to store water to be applied to the sheet, and a pressurizing member that pressurizes the water in the water reservoir to apply the water to the sheet crimping range. The sheet mentioned in the present invention refers to a thin material into which water is permeated to unfold the fibers thereof. Further, the water mentioned in the present invention refers to a liquid having the same properties as those of water. 
     According to the present invention, water is pressurized to be applied to the crimping range of a sheet made of a water-permeable paper material, so that permeation of water into the sheets is facilitated, making it easy for the fibers of the sheets to be unfolded. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a view illustrating the entire configuration of a system having a combined structure of an image forming device and a sheet processing device according to the present invention; 
         FIG. 2  is a view illustrating the entire configuration of the sheet processing device according to an embodiment of the present invention; 
         FIG. 3  is a plan view of a processing tray and a binding unit; 
         FIGS. 4A and 4B  are perspective views of the binding unit, in which  FIG. 4A  illustrates the back side of the binding unit and  FIG. 4B  illustrates the front side thereof; 
         FIGS. 5A and 5B  are side views of the binding unit, in which  FIG. 5A  illustrates the binding unit as viewed from the rear side of the sheet processing device, and  FIG. 5B  illustrates the binding unit as viewed from the front side thereof; 
         FIGS. 6A and 6B  are perspective views of the water application/pressurizing part of the binding unit, in which  FIG. 6A  is a perspective view from the side, and  FIG. 6B  is a perspective view from slightly above; 
         FIGS. 7A and 7B  are cross-sectional views of the water application/pressurizing part of the binding unit, in which  FIG. 7A  is a front view, and  FIG. 7B  is a side view; 
         FIGS. 8A and 8B  are perspective views for explaining a state where the water application/pressurizing part of the binding unit is compressed, in which  FIG. 8A  is a perspective view from slight above, and  FIG. 8B  is a perspective view from slightly below; 
         FIGS. 9A and 9B  are cross-sectional views for explaining a state where the water application/pressurizing part of the binding unit is compressed, in which  FIG. 9A  is a cross-sectional front view, and  FIG. 9B  is a cross-sectional side view; 
         FIG. 10  is a cross-sectional view of a water replenishment pump unit; 
         FIG. 11  is an exploded perspective view of the water replenishment piston part of the water replenishment pump unit; 
         FIG. 12  is an enlarged view of the water replenishment piston part of the water replenishment pump unit; 
         FIG. 13  is an enlarged view for explaining a state where water is ejected by the water replenishment piston part; 
         FIGS. 14A to 14C  are views illustrating a state where the binding unit performs crimp-binding without water application as viewed from the front side, in which  FIG. 14A  illustrates a sheet receiving state,  FIG. 14B  illustrates a pressure contact state, and  FIG. 14C  illustrates a sheet crimping state; 
         FIGS. 15A to 15C  are views illustrating a state where the binding unit performs crimp-binding without water application as viewed from the rear side, in which  FIG. 15A  illustrates a sheet receiving state,  FIG. 15B  illustrates a pressure contact state, and  FIG. 15C  illustrates a sheet crimping state; 
         FIGS. 16A to 16C  are cross-sectional views illustrating a state where the binding unit performs crimp-binding without water application, in which  FIG. 16A  illustrates a sheet receiving state,  FIG. 16B  illustrates a pressure contact state, and  FIG. 16C  illustrates a sheet crimping state; 
         FIGS. 17A to 17C  are views illustrating a state where the binding unit performs water application/crimp-binding as viewed from the front side, in which  FIG. 17A  illustrates a sheet receiving state,  FIG. 17B  illustrates a pressure contact state, and  FIG. 17C  illustrates a sheet crimping state; 
         FIGS. 18A to 18C  are views illustrating a state where the binding unit performs water application/crimp-binding as viewed from the rear side, in which  FIG. 18A  illustrates a sheet receiving state,  FIG. 18B  illustrates a pressure contact state, and  FIG. 18C  illustrates a sheet crimping state; 
         FIGS. 19A to 19C  are cross-sectional views illustrating a state where the binding unit performs water application/crimp-binding, in which  FIG. 19A  illustrates a sheet receiving state,  FIG. 19B  illustrates a pressure contact state, and  FIG. 19C  illustrates a sheet crimping state; 
         FIGS. 20A to 20C  are views for explaining pressure teeth and receiving teeth of the water application/pressurizing part, in which  FIG. 20A  is a plan view of the pressure teeth,  FIG. 20B  is a cross-sectional view of the pressure teeth and receiving teeth, and  FIG. 20C  is a bottom view of the pressure teeth; 
         FIG. 21  is an enlarged view for explaining a state where the pressure teeth and the receiving teeth mate with each other, in which the chain double-dashed circle is an enlarged view of the mating state; 
         FIG. 22  is a view for explaining the position of the sheet bundle held between a pressure teeth support part and a receiving teeth support part; 
         FIGS. 23A to 23C  are views for explaining the relationship between the positions of the pressure teeth support part and receiving teeth support part and the position of sheets held between the pressure teeth support part and the receiving teeth support part, in which  FIG. 23A  is an explanatory view illustrating the state of  FIG. 22  and  FIGS. 23B and 23C  are explanatory views each illustrating a configuration with a problem; 
         FIGS. 24A to 24D  are views for explaining the relationship between the number of sheets placed on the processing tray and pressurization using pressure teeth/water application, in which  FIG. 24A  is a view for explaining the relationship between the pressure teeth and the number of sheets,  FIG. 24B  is a view for explaining a configuration where water application and crimping are performed for each of added sheets,  FIG. 24C  is a view for explaining a configuration where water application is performed for each of added sheets and crimping is performed after placement of the last sheet (after accumulation of certain number of added sheets), and  FIG. 24D  is a view for explaining a configuration in which water application and crimping are performed after placement of the last added sheet (after accumulation of a certain number of added sheets); 
         FIG. 25  is an explanatory view illustrating a state where the water replenishment pump unit is removed from the binding unit; 
         FIG. 26  is a block diagram of the control configuration of the device according to the embodiment of the present invention; 
         FIG. 27  is a view illustrating a modification (Modification 1) of the configuration illustrated in  FIG. 3 , in which a stapling unit is used in combination with the water application/crimp-binding unit; 
         FIGS. 28A to 28F  are views illustrating a modification (Modification 2) in which the position of a water supply hole (water supply tube) of the pressure teeth and the shape of the receiving teeth are changed, in which  FIG. 28A  illustrates a configuration in which the water supply holes are formed in respective ridges of the pressure teeth,  FIG. 28B  illustrates a configuration in which communication holes of the receiving teeth are each formed into a square shape in cross section,  FIG. 28C  illustrates a configuration in which the communication holes of the receiving teeth are formed in respective receiving ridges,  FIG. 28D  is a cross-sectional view of side view direction of  FIG. 28A ,  FIG. 28E  is a cross-sectional view of side view direction of  FIG. 28B , and  FIG. 28F  is a cross-sectional view of side view direction of  FIG. 28 c   ; and 
         FIGS. 29A and 29B  are explanatory views illustrating a configuration in which an extension tank for increasing the capacity of the water replenishment tank is additionally installed, in which  FIG. 29A  illustrates a state where the amount of water in the extension tank is increased, and  FIG. 29B  illustrates a state where the amount of water in the extension tank is reduced. 
     
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Hereinafter, a preferred embodiment of the present invention will be described in detail with reference to the accompanying drawings. Throughout the description, the same reference numerals are given to the same or similar constituent elements. 
     Image Forming Device 
     An image forming device A illustrated in  FIG. 1  will be described. The illustrated image forming device A is constituted of an image forming main body A 1  and a sheet processing device (finisher) B. The image forming main body A 1  is an electrostatic printing mechanism and constituted of a reading device A 2  and a document conveying device A 3 . A device housing  1  of the image forming main body A 1  incorporates therein a sheet supply section  2 , an image forming section  3 , a sheet discharge section  4 , and a data processing section  5 . 
     The sheet supply section  2  has cassettes  2   a  to  2   c  for storing sheets of different sizes to be image-formed and is configured to deliver sheets of a size specified through an image forming control section  200  and a sheet supply control section  202  to a sheet supply path  6 . Thus, the plurality of cassettes  2   a  to  2   c  are detachably mounted in the device housing  1 , and each cassette incorporates therein a separation mechanism for separating the stored sheets one from another and a sheet supply mechanism for delivering the sheets. The sheet supply path  6  is provided with a conveying roller  7  that conveys downstream the sheets fed from the plurality of cassettes  2   a  to  2   c  and a resist roller pair  8  that aligns the front ends of the sheets. The resist roller pair  8  is provided at the end portion of the sheet supply path  6 . 
     The above sheet supply path  6  is connected with a large capacity cassette  2   d  and a manual feed tray  2   e . The large capacity cassette  2   d  is an option unit that stores sheets of a size to be frequently used, and the manual feed tray  2   e  is configured to feed a special sheet hard to separately feed, such as a cardboard sheet, a coating sheet, and a film sheet. 
     The image forming section  3  is, for example, an electrostatic printing mechanism and includes a photoreceptor  9  (drum, belt) and a light emitter  10  for emitting an optical beam to the photoreceptor  9 . Further, a developer  11  and a cleaner (not illustrated) are disposed around the rotating photoreceptor  9 . The illustrated image forming section  3  is a monochrome printing mechanism, in which a latent image is optically formed on the photoreceptor  9  by the light emitter  10 , and toner ink is deposited onto the latent image by the developer  11 . 
     Then, a sheet is fed along the sheet supply path  6  to the image forming section  3  at the timing when an image is formed on the photoreceptor  9 , the image on the photoreceptor  9  is transferred onto the sheet by a transfer charger  12 , and the image is fixed to the sheet by a fixing unit (roller)  13  disposed on the sheet discharge path  14 . On the sheet discharge path  14 , there are provided a sheet discharge roller pair  15  and a main body sheet discharge port  16 . The image-formed sheet is conveyed to the sheet processing device B to be described later. 
     The aforementioned reading device A 2  is constituted of a platen  17  on which a document is placed, optical carriages  18  and  19  configured to be reciprocated along the platen  17 , light sources mounted on the respective optical carriages  18  and  19 , and a reduction optical system (combination of mirrors and lenses) that guides a reflected light from the document placed on the platen  17  to a photoelectric conversion member  20 . 
     The reading device A 2  further includes a traveling platen  21  as a second platen at the side of the platen  17 . On the traveling platen  21 , an image of a sheet document fed from the document conveying device A 3  is read by the above optical carriages  18 ,  19  and the photoelectric conversion member  20 . The photoelectric conversion member  20  electrically transfers image data obtained through photoelectric conversion to the mage forming section  3 . 
     The document conveying device A 3  is constituted of a document conveying path  23  that guides a sheet document fed from a document supply tray  22  to the traveling platen  21  and a document discharge tray  24  that stores a document whose image has been read on the traveling platen  21 . 
     The image forming main body A 1  is not limited to the above-described mechanism, and may be an offset printing mechanism, an inkjet printing mechanism, or an ink ribbon transfer (thermal transfer ribbon printing, sublimation ribbon printing, etc.). 
     Sheet Processing Device 
     The sheet processing device B receives, through an entrance  36 , a sheet carried out from the main body sheet discharge port  16  of the image forming main body A 1  and processes the sheet, and is called “finisher”. The sheet processing device B has the following modes: (1) printout mode; (2) jog sorting mode; (3) binding mode; (4) bookbinding (saddle-stitching) mode; and (5) manual binding mode. Details of the above modes will be described later. 
     The sheet processing device B is not necessarily required to have all the abovementioned modes. The sheet processing device B may be appropriately arranged in accordance with device specifications (design specifications). The sheet processing device B disclosed herein includes a binding part B 1  (end face binding part) that binds sheets at an end portion thereof from the front and back sides, a saddle-stitching part B 2  that saddle-stitches sheets at a middle portion thereof in the sheet conveying direction, and an escape part B 3  that does not perform binding but performs sorting and the like. As far as the present invention is concerned, it is required to provide a sheet loading/stacking configuration that once conveys sheets to a reference position for alignment before sheet binding. 
       FIG. 2  illustrates the configuration of the sheet processing device B. The sheet processing device B has the sheet entrance  36  connected to the main body sheet discharge port  16  of the image forming device A. At the entrance  36 , an entrance sensor  38  for detecting a sheet fed through the entrance  36  and a punch unit  40  that punches a sheet at an end portion thereof as needed are disposed. Below the punch unit  40 , a punch chip box is detachably attached to a processing device frame  30 . A carry-in roller  41  and a conveying roller  48  that convey a sheet to the downstream are provided at the rear of the punch unit  40 . 
     A substantially linearly extending conveying path  43  along which a sheet is conveyed to a processing tray  58  side, an escape path  33  branched upward from the conveying path  43 , and a saddle-stitching path  65  that guides a switched-back sheet passing through a merging part  45  of the conveying path  43  are provided downward of the carry-in roller  41 . A sheet conveyed by the carry-in roller  41  is conveyed to the escape path  33  or the saddle-stitching path  65 . This switching between the escape path  33  and saddle-stitching path  65  is made by first and second gates  42  and  44  provided in the middle of the conveying path  43 . 
     Escape Part 
     A sheet conveyed substantially linearly along the conveying path  43  is accumulated in a loading tray  34  as a single sheet or a sheet bundle after once being loaded on the processing tray  58  or directly through a sheet discharge port  54 . On the other hand, a sheet conveyed from the conveying path  43  to the escape path  33  provided above the conveying path  43  is accumulated in an escape tray  32 . In this case, although not illustrated, a discharge roller at the last stage is configured to be moved at sheet discharge in a direction crossing the extending direction of the conveying path  43  for each specified number of sheets. This enables sorting jog of the escape part B 3 . 
     Saddle-Stitching Part 
     The conveying path  43  is provided with a sheet sensor  39  for detecting the rear end of a conveyed sheet. After detection by the sheet sensor  39 , the conveying roller  48  is reversely rotated to convey the sheet to a branch roller  64 . The branch roller  64  conveys the sheet along the saddle-stitching path  65 , and the conveyed sheet is accumulated in a slightly inclined stacker  72  for saddle-stitching. A bundle of the accumulated sheets is positioned by upward movement of a saddle-stitching sheet stopper  74  such that the middle of the sheet bundle in the conveying direction corresponds to a binding position of a saddle-stitching unit  66 . 
     The sheet bundle thus positioned is bound by the saddle-stitching unit  66  of the saddle-stitching part B 2 . The bound sheet bundle is then slightly lowered with its binding position aligned to a folding position and folded into two at the folding position by a folding blade  70  and a folding roller  68 . The sheet bundle folded into two by the folding roller  68  is discharged to a bundle stacker  78  by a bundle discharge roller  76  and accumulated there as a saddle-stitched book. As described above, the escape part B 3  and saddle-stitching part B 2  are positioned above and below the conveying path  43 , respectively. 
     End Face Binding Part (Processing Tray and Its Peripheral Members) 
     The end face binding part B 1  is constituted of the processing tray  58  and a (water application/crimp)-binding unit  60 . The processing tray  58  on which a sheet is temporarily placed is positioned with a level difference from the exit of the conveying roller  48  so as to process a sheet conveyed from the conveying path  43  to the conveying roller  48 . A drop-in guide  46  is provided at the exit of the conveying roller  48 . The drop-in guide  46  drops a sheet to the loading face of the processing tray  58  at the same time when the sheet is carried out from the conveying roller  48 . A return paddle  51  having a fin-shaped elastic piece is positioned downstream of the drop-in guide  46  as a transfer member for switch-back transfer of a sheet in the processing tray  58 . 
     A sheet discharge roller  52  is disposed on the side of the return paddle  51  where the loading tray  34  is located. The sheet discharge roller  52  is constituted of a turnable upper discharge roller  52   a  and a fixed lower discharge roller  52   b . The sheet discharge roller  52  performs an operation to nip a sheet conveyed from the conveying roller  48  for conveyance to the loading tray  34 , to nip a first sheet of the sheets to be stored in the processing tray  58  for switch-back conveyance, or to convey a sheet bundle loaded on the processing tray  58  to the loading tray  34 . Further, in the sheet discharge roller  52  disclosed herein, the upper discharge roller  52   a  is rotated in the same direction as the return paddle  51  to assist conveyance of the sheet on the processing tray  58  at the time of the switch-back conveyance. 
     As illustrated in  FIG. 3 , an aligning plate  59  configured to be moved in the sheet width direction crossing the sheet conveying direction every time a sheet is carried out from the conveying roller  48  is provided on the processing tray  58 . The aligning plate  59  is positioned on both sides of a sheet in the sheet width direction so as to sandwich the sheet and is driven to move by an aligning plate motor  59 M in such a direction that the distance between the both sides of the aligning plate  59  becomes small for alignment of the sheet in the width direction. The sheet discharge port  54  is formed at one end of the processing tray  58 , and a reference stopper  62  is provided at the other end of the processing tray  58  obliquely downward of the sheet discharge port  54  so as to receive abutment of a sheet switch-back conveyed by the return paddle  51  and the like. 
     As illustrated in  FIG. 2 , a carry-in guide  57  for guiding a sheet being switch-back conveyed is provided between the return paddle  51  and the reference stopper  62 . The carry-in guide  57  is turnably provided around the lower-side axis of the conveying roller  48  so as to be suspended therefrom by its own weight and guides carry-in of the sheet being switch-back conveyed. Further, there is provided a return belt  61  that further conveys the sheet conveyed by the return paddle  51  toward the reference stopper  62 . Further, a binding unit  60  is provided at the end portions of the stacked sheets (sheet bundle) stopped by the reference stopper  62 . 
     The binding unit  60  illustrated in  FIGS. 2 and 3  adopts crimp-binding to bind sheets by crimping the sheets using pressure teeth without using a metal staple needle and further performs so-called a water application/crimp-binding of applying water to the sheets at crimping and binding them. The sheet mentioned in the present invention refers to a thin material into which water is permeated to unfold the fibers thereof. Further, the water mentioned in the present invention refers to a liquid having the same properties as those of water. Details of the water application/crimp-binding will be described later using  FIGS. 4A and 4B  and subsequent figures. 
     The binding unit  60  that can perform the aforementioned water application/crimp-binding is driven to move in the sheet width direction (between the front and the rear of the device) by a binding unit moving motor (not illustrated) and can bind a sheet bundle at a corner portion thereof or a plurality of positions around the center of the end portion. In the example of  FIG. 3 , the binding unit  60  can be moved to a rear side corner  60  (R) which is the far side from an operator of the sheet processing device B, two positions  60  ( 2 ) along the edge of the sheet in the width direction, and a front side corner  60  (F) which is the front side of the device B or the operator side. 
     Further, the binding unit  60  disclosed herein has a manual binding position at which a sheet bundle inserted through a bundle manual feed port of the device frame  30  is bound. The manual binding position is located at the same position as a position at which a water replenishment tank  174  to be described later is replenished with water and a home position at which positioning of the initial position of the movement of the binding unit  60  is performed. 
     After completion of the binding of a sheet bundle by the binding unit  60 , the bound sheet bundle is pushed by the reference stopper  62  to be moved to the middle of the processing tray  58 . Thereafter, the upper discharge roller  52   a  is lowered during the pushing, and the bound sheet bundle is nipped by the upper and lower discharge rollers  52   a  and  52   b  and discharged toward the loading tray  34  through the sheet discharge port  54 . 
     The loading tray  34  for accumulating a single sheet or a bound sheet bundle is provided below the sheet discharge port  54 . To keep constant the height position of the upper surface of the sheets accumulated on the loading tray  34 , the upper surface of the sheets is detected, and when a certain amount of sheets are accumulated, a loading tray motor  34 M is driven to move the loading tray  34  to keep constant the height position of the upper surface of the sheets from the sheet discharge port  54 . 
     (Water Application/Crimp)-Binding Unit 
     The following describes the binding unit  60  which characterizes the present invention with reference to  FIGS. 4A and 4B  and subsequent figures. At the binding unit  60 , water is applied to the sheet binding position before crimping.  FIGS. 4A and 4B  are perspective views of the (water application/crimp)-binding unit  60 .  FIG. 4A  illustrates the back side (the side remote from the operator) of the binding unit  60 , and  FIG. 4B  illustrates the front side (the side near the operator) thereof.  FIGS. 5A and 5B  are side views of the binding unit  60 .  FIG. 5A  illustrates the binding unit  60  as viewed from the rear side of the sheet processing device, and  FIG. 5B  illustrates the binding unit  60  as viewed from the front side thereof. 
     As illustrated in  FIGS. 4A to 5B , the binding unit  60  is constituted of a water application/pressurizing part  80 , a receiving teeth part  126 , and a water replenishment pump part (pump unit)  150 . The water application/pressurizing part  80  is configured to apply water to a sheet and has pressure teeth  82  (one of a pair of pressure teeth) configured to be vertically movable. The receiving teeth part  126  has receiving teeth  130 . The water replenishment pump part  150  is provided for water replenishment to the water application/pressurizing part  80 . The pressure teeth  82  (upper-side teeth) are provided on a pressure teeth support part  84  and is surrounded by an elastic member  92  such as a rubber plate. 
     The receiving teeth  130  which is the other one (lower-side teeth) of the pair of teeth are supported by a receiving teeth support part  128  to constitute the receiving teeth part  126 . Sheets (sheet bundle) placed on the processing tray  58  are sandwiched between the pressure teeth  82  and the receiving teeth  130 . 
     As illustrated in  FIG. 4B , a cylinder  90  constituting a water reservoir  88  for retaining water to be applied to sheets is disposed on the back side of the pressure teeth  82 , and a cylinder guide  108  is positioned radially outside a piston  104  to be described later. The piston  104  and cylinder  90  constitute a pressurizing member (water application member) for water application. 
     The receiving teeth  130  are supported by the receiving teeth support part  128 , and the receiving teeth support part  128  also supports the lower surface of a sheet. Further, a drain pan  133  for receiving water remaining at water application is disposed below the receiving teeth support part  128 . 
     Further, as illustrated in  FIG. 4A , the water replenishment pump unit  150  serving as a water replenishment pump part that replenishes the water reservoir  88  with water is housed in an outer frame  120  of the binding unit  60  so as to be adjacent to the rear side of the pressure teeth  82  and receiving teeth  130 . While the details will be described later, the water replenishment pump unit  150  is constituted of a water replenishment piston part  154  that supplies water to the water reservoir  88 , a water replenishment head part  156  that moves the water replenishment piston part  154 , and a water replenishment tank part  152  having a water replenishment tank  174  for storing water for replenishment. In  FIG. 4A , a pump holding cover  192  that covers the water replenishment tank  174  can be seen. 
     A compression spring  96  is provided at the left and right of the cylinder  90  constituting the water reservoir  88  so as to be vertically sandwiched between the pressure teeth support part  84  that supports the pressure teeth  82  and the elastic member (rubber plate)  92  and a pressing plate  102  that moves up and down the pressure teeth  82 . 
     Vertical Movement of Pressing Plate 
     The pressing plate  102  is driven by a drive motor (binding motor  60 M) disposed in a space defined by the receiving teeth support part  128  and the outer frame  120  in the following manner. That is, as illustrated in  FIGS. 4A and 5A , an intermediate gear  138  is engaged with a motor output shaft gear  136  mounted to the output shaft of the binding motor  60 M as the drive motor on the rear side outer frame  120 . 
     The torque of the intermediate gear  138  is transmitted to a cam gear  140  that rotates a moving cam  145  and a pinion gear  142  that moves a support rack  144  to a position at which it supports a water replenishment tank bottom  175  and to a position at which it does not. The pinion gear  142  is constituted of a pinion gear  142   a  that receives transmission of the torque from the intermediate gear  138  to be rotated together with its shaft and a pinion gear  142   b  that transmits the torque to the support rack  144  through a one-way clutch  147  with the shaft. With this configuration, whether or not to move the support rack  144  is selected depending on the rotation direction of the drive motor  60 M. As a result, the water replenishment piston part  154  is operated only when required. Details of this mechanism will be described later. 
     The moving cam  145  is provided on both sides (front and rear sides) of the outer frame  120 . Thus, a turning arm  134  moved by the moving cam  145  is mounted to the both sides of the outer frame  120  so as to be turned about an arm fulcrum  146  mounted to the outer frame  120 . The turning arm  134  is kept in a state where an arm rear end  143  always abuts against the moving cam  145  by a return spring  149  stretched between the turning arm  134  and the outer frame  120 . 
     On the other hand, an arm leading end slit  148  formed at the leading end of the turning arm  134  receives insertion of an upper moving pin  110  of the pressing plate  102 . Thus, when the moving cam  145  is rotated, the leading end side of the turning arm  134  is vertically moved to vertically move the pressing plate  102 . The upper moving pin  110  and a lower moving pin  112  of the pressing plate  102  are inserted into a guide slit  124  of the outer frame  120  on the front side (pressure teeth  82  side) of the pressing plate  102 . 
     On the rear side (water replenishment pump unit  150  side) of the pressing plate  102  as well, a rear guide pin  116  of the pressing plate  102  is inserted into the guide slit  124  of the outer frame  120 . Since the upper moving pin  110  is inserted into the arm leading end slit  148  of the turning arm  134 , the pressing plate  102  can be vertically moved by turning of the turning arm  134 . In this way, the pressing plate  102  and turning arm  134  constitute a moving member. 
     Water Application/Pressurizing Part 
     The pressing plate  102  vertically moves the water application/pressurizing part  80 . This mechanism will be described with reference to  FIGS. 6A to 9B .  FIGS. 6A and 6B  are perspective views of the water application/pressurizing part  80  of the binding unit  60 .  FIG. 6A  is a perspective view from the side, and  FIG. 6B  is a perspective view from slightly above.  FIGS. 7A and 7B  are cross-sectional views of the water application/pressurizing part  80 .  FIG. 7A  is a front view, and  FIG. 7B  is a side view. 
     The water application/pressurizing part  80  includes the pressing plate  102 , the pressure teeth support part  84 , and the compression spring  96  interposed between the pressing plate  102  and the pressure teeth support part  84 . The pressure teeth  82  and the elastic member  92  (rubber plate) that surrounds the pressure teeth  82  are provided on the side of pressure teeth support part  84  that contacts a sheet. On the back surface side of the pressure teeth  82  (pressure teeth back surface side), the cylinder  90  integrally formed with the pressure teeth support part  84  and a guide bar  94  around which the compression spring  96  is wound are provided. The guide bar  94  is provided on both sides of the cylinder  90 . The leading end of the guide bar  94  is kept fitted in a guide hole  114  of the pressing plate  102 . 
     As illustrated in  FIGS. 7A and 7B , the water reservoir  88  is formed in the cylinder  90 . The water reservoir  88  occupies about one-third of the cylinder  90  in the height direction and retains water to be applied to sheets. Further, the cylinder  90  is cut to form a replenishment port  98  for receiving water from the water replenishment pump unit  150  to be described later. The illustrated cylinder  90  has the pressure teeth  82  formed integrally therewith, and water supply holes (water supply tubes)  86  are formed in the pressure teeth  82  so as to allow water in the water reservoir  88  to be applied to sheets. 
     The piston  104  is positioned above the cylinder  90 . The piston  104  is configured to be inserted into the cylinder  90  to pressurize water in the water reservoir  88  so as to allow the water to be applied to sheets through the water supply holes  86  of the pressure teeth  82 . The piston  104  is fixed to the pressing plate  102  at the upper end thereof. A piston packing  106  is circumferentially fitted to the insertion portion of the piston  104  into the cylinder  90 . Although the piston packing  106  is fitted in one place in the example of  FIGS. 7A and 7B , it may be fitted in two or more places, which increases pressurization at water application. 
     The pressing plate  102  has the cylinder guide  108  that is moved to overlap the cylinder  90  at a position radially outside thereof so as to facilitate insertion of the piston  104  and water application operation. The pressing plate  102  has the guide hole  114 , the upper and lower moving pins  110  and  112  to be inserted into the guide slit  124  of the outer frame  120 , and the rear guide pin  116 . The upper and lower moving pins  110 ,  112 , and the rear guide pin  116  are fixedly formed. The upper moving pin  110  extends outside slightly longer than other pins so as to allow insertion into the arm leading end slit  148  of the turning arm  134  turning outside the outer frame  120 . 
     Water Application/Pressurizing Part in Compressed State 
     A state where the thus configured water application/pressurizing part  80  is compressed by the turning arm  134  is illustrated in  FIGS. 8A and 9B .  FIGS. 8A and 8B  are perspective views of the water application/pressurizing part  80  from slightly above and below, respectively. The operation of the turning arm  134  that brings the water application/pressurizing part  80  into the compressed state will be described later using  FIGS. 14A to 19C . 
     In the compressed state, the pressing plate  102  is made to abut against the receiving teeth support part  128  by the turning arm  134 , the compression spring  96  wound around the guide bar  94  is compressed, and the guide bar  94  protrudes from the pressing plate  102  through the guide hole  114 . As illustrated in  FIG. 8B , which is a view illustrating this compressed state as viewed from the receiving teeth support part  128  side, the pressure teeth  82  having the water supply holes (water supply tubes) are surrounded by the elastic member  92  such as a rubber plate. That is, the pressure teeth support part  84  is pressed against a sheet bundle first, and then water in the water reservoir  88  is applied to the sheet bundle and, at this time, the elastic member prevents the water applied to an area other than the crimping range of the pressure teeth  82  from being spread. 
       FIGS. 9A and 9B  are cross-sectional views of the water application/pressurizing part  80 .  FIG. 9A  is a cross-sectional front view taken in a direction crossing both the cylinder  90  and the guide bar  94 .  FIG. 9B  is a cross-sectional view taken in a direction perpendicular to that of  FIG. 9A . As illustrated in  FIGS. 9A and 9B , water retained in the water reservoir  88  formed in the cylinder  90  is applied to sheets through the water supply holes (water supply tubes)  86  of the pressure teeth  82  by the piston  104 . In this state, the pressure teeth  82  receives force from the pressing plate  102  by the piston  104  and presses/crimps the water-applied sheets between themselves and the receiving teeth  130  mating with the pressure teeth  82 . 
     The cylinder  90  is formed such that the inner diameter thereof is reduced downward, and as described above, the water reservoir  88  that retains water to be applied to sheets is formed so as to occupy about one-third of the cylinder  90  in the height direction. At this position, the water retained in the water reservoir  88  is pressurized by the piston  104  for water application. Above this position, water from the replenishment pump unit  150  is supplied to the water reservoir  88  through the replenishment port  98 , followed by subsequent operation of the piston  104 . Thus, the amount of water to be applied to sheets per one crimp-binding operation corresponds to the amount of water that can be retained in the water reservoir  88 . 
     Water Replenishment Pump Part 
     The following describes the water replenishment pump unit  150  as the water replenishment pump part that replenishes the water reservoir  88  with water through the replenishment port  98  by referring to  FIGS. 10 to 13 . As already described using  FIGS. 4A and 4B , the water replenishment pump unit  150  is inwardly installed in the outer frame  120  of the binding unit  60  like the pressure teeth support part  84  and the receiving teeth part  126 . This eliminates the need to route water replenishment pipes from outside of the binding unit  60 , facilitating the handling and making the device compact. 
     This water replenishment pump unit  150  will be described below with reference to the accompanying drawings.  FIG. 10  is a cross-sectional view of the water replenishment pump unit  150 .  FIG. 11  is an exploded perspective view of the water replenishment piston part  154  which is an important constituent element of the water replenishment pump unit  150 .  FIG. 12  is an enlarged view of the water replenishment piston part  154 .  FIG. 13  is an enlarged view for explaining a state where water is ejected by the water replenishment piston part  154 . 
     As illustrated in  FIG. 10 , the water replenishment pump unit  150  is constituted of the water replenishment head part  156  pressed by the pressing plate  102  to be vertically moved, the water replenishment piston part  154  that temporarily retains water and ejects the water to the water replenishment head part  156 , and the water replenishment tank part  152  for storing water to be supplied to the water replenishment piston part  154 . Water ejected from the water replenishment piston part  154  by the vertical movement of the water replenishment head part  156  is supplied to the water reservoir  88  through a water replenishment joint part  158  whose projection port extends from the water replenishment head part  156  to the replenishment port  98  of the water application/pressurizing part  80 . 
     A moving plate  176  is provided in the water replenishment tank part  152  so as to be vertically moved with a reduction in the amount of water every time the water is ejected to the water replenishment joint part  158  by the water replenishment piston part  154  to be described using  FIGS. 11 to 13 . An air hole  178  allowing the movement of the moving plate  176  is formed in the water replenishment tank bottom  175  of the water replenishment tank part  152 . 
     Water Replenishment Piston Part 
     The following describes the water replenishment piston part  154  that ejects water to the water replenishment head part  156  with reference to  FIGS. 11 and 12 . The water replenishment piston part  154  has a tank cap  172  screwed to the water replenishment tank part  152  and a water replenishment cylinder  167  that is fixed to the tank cap  172  and temporarily retains water from the water replenishment tank part  152 . A sealing  171  is provided between the tank cap  172  and the water replenishment tank  174  of the water replenishment tank part  152 . In the binding unit  60 , the tank cap  172  is supported by being fitted into a curved portion (see  FIGS. 6 and 8 ) below the replenishment port  98  of the pressure teeth support part  84 . 
     Further, an upper piston  162  is provided at the upper portion of the water replenishment cylinder  167 . The upper piston  162  is vertically moved by the vertical movement of the water replenishment head part  156 . The upper piston  162  is wound with an upper spring  169 , and a pump valve  165  also wound with the upper spring  169  is disposed below the upper piston  162 . Inside the pump valve  165 , a lower piston  163  wound with a lower spring  170  is positioned between the pump valve  165  and the lower portion of the water replenishment cylinder  167 . A lower piston protrusion portion  164  pressed to the pump valve  165  for sealing is provided in the circumferential direction of the lower piston  163 . The lower piston protrusion portion  164  is pressed by the lower spring  170 . 
     A ball valve  166  for taking in water from the water replenishment tank  174  and for sealing inside the water replenishment cylinder  167  is provided at the lower end of the water replenishment cylinder  167 . When the pressure inside the water replenishment cylinder  167  is increased, the ball valve  166  is positioned at the lower end of the water replenishment cylinder  167 ; while, when the pressure inside the water replenishment cylinder  167  is reduced, the ball valve  166  is moved slightly upward so as to take in water from the water replenishment tank  174 . 
     Water Replenishment Operation 
     As illustrated in  FIG. 13 , in the thus configured water replenishment pump unit  150 , when the water replenishment head part  156  is pressed by the pressing plate  102  to be moved down, the upper piston  162  is also moved down. This presses the upper spring  169  wound around the upper piston  162  to press the pump valve  165 . Since the pump valve  165  is thus moved down, the ball valve  166  closes the lower end of the water replenishment cylinder  167 , so that the internal pressure of the water replenishment cylinder  167  increases. 
     When the internal pressure of the water replenishment cylinder  167  exceeds a certain value, the upper spring  169  wound around the pump valve  165  and the upper piston  162  contracts, whereby a gap is generated between the pump valve  165  and lower piston protrusion portion  164 . Through this gap, water in the water replenishment cylinder  167  goes outside and is then passed through the pump valve  165 , the upper portion of the lower piston  163 , and the upper piston  162  as denoted by the arrows of  FIG. 13  to be ejected from the water replenishment joint part  158  of the water replenishment head part  156  to the water reservoir  88 . When the amount of water in the water replenishment tank  174  reduces, the moving plate  176  is moved up due to decompression inside the water replenishment tank  174  so as to maintain the liquid surface level in the water replenishment tank  174  constant. 
     As described above, the water in the water replenishment tank  174  is supplied to the replenishment port  98  of the water application/pressurizing part  80  through the water replenishment joint part  158  every time the water replenishment head part  156  is pressed by the pressing plate  102 . The mechanism of the water replenishment pump unit  150  illustrated in  FIGS. 10 to 13  is described in detail in Japanese Patent Application Laid-Open Publication No. 2014-240286 that discloses a similar device. 
     The following describes a crimp-binding operation for a sheet bundle placed on the processing tray  58  performed in the disclosed binding unit  60 . When executing the crimping using the pair of pressure teeth (pressure teeth  82  and receiving teeth  130 ), the binding unit  60  can select whether to perform water application (water application/crimp-binding, in which crimping is performed after applying water to the crimping part) or not (crimp-binding without water application). 
     Crimp-Binding without Water Application 
     With reference to  FIGS. 14A to 16C , the crimp-binding using the pressure teeth  82  without applying water to the crimping range will be described.  FIGS. 14A to 14C  are views illustrating the binding unit  60  as viewed from the front side,  FIGS. 15A to 15C  are views of the binding unit  60  as viewed from the rear side, and  FIGS. 16A to 16C  are cross-sectional views of the binding unit  60 .  FIGS. 14A, 15A, and 16A  illustrate a state where the pressure teeth support part  84  (pressure teeth  82 ) is separated from sheets,  FIGS. 14B, 15B, and 16B  illustrate a state where the pressure teeth support part  84  is brought into pressure contact with sheets, and  FIGS. 14C, 15C, and 16C  illustrate a state where sheets are crimped without water application. 
       FIGS. 14A, 15A, and 16A  illustrate a sheet receiving stage. Sheets are placed on the processing tray  58 . More specifically, the sheets are placed on the receiving teeth support part  128  and between the pressure teeth  82  and the receiving teeth  130  of the binding unit  60 . For descriptive convenience, the sheets are not illustrated in  FIGS. 14A to 15C  and illustrated in  FIGS. 16A to 16C . When the specified number of sheets are loaded on the receiving teeth support part  128  provided with the receiving teeth  130 , the binding motor  60 M starts driving. 
     In this case, water application is not performed, so that the binding motor  60 M is driven in a direction to turn the moving cam  145  in the clockwise direction on the front side ( FIGS. 14A to 14C ) and turn the moving cam  145  in the counterclockwise direction on the rear side ( FIGS. 15A to 15C ). This moves the protruding side of the moving cam  145  in a direction to press down the leading end of the turning arm  134 . On the other hand, the pinion gear  142  (pinion gear  142   b ) engaged with the intermediate gear  138  does not move the support rack  144  by the action of the one-way clutch  147 . 
     In the state illustrated in  FIGS. 14B, 15B, and 16B , the pressing plate  102  is moved down to bring the pressure teeth support part  84  having the pressure teeth  82  into close contact with the sheets. When the pressing plate  102  is pressurized in this state, the pressure teeth support part  84  is pressed against the sheets by the compression spring  96  interposed between the pressing plate  102  and the pressure teeth support part  84 . The elastic member (rubber plate)  92  that surrounds the pressure teeth  82  is provided in the pressure teeth support part  84  on the pressure teeth  82  side and is brought into pressure contact with the sheets so as not to generate a gap between the pressure teeth  82  and the sheet surface. In the device disclosed herein, a force of 70 kgf to 100 kgf is applied to the sheets. 
     In the state illustrated in  FIGS. 14C, 15C, and 16C , the turning arm  134  is moved by the moving cam  145  in a state where the pressure teeth support part  84  is brought into close contact with the sheets to move down the pressing plate  102 . Then, the piston  104  is inserted inside the cylinder  90  to directly press the pressure teeth support part  84  to crimp the sheets with the pressure teeth  82 . At this time, a voltage to the binding motor  60 M is controlled so as to generate a pressurizing force of 500 kgf to 700 kgf (600 kgf in the device disclosed herein). The control of the output torque of the binding motor  60 M is disclosed in Japanese Patent Application Laid-Open Publication No. 2015-199234 and the like and is already known, so description thereof is omitted here. 
     In the water replenishment pump unit  150 , the water replenishment head part  156  is pressed by the pressing plate  102  in a state where the water replenishment pump unit  150  is sandwiched between the pressing plate  102  and the support rack  144 , whereby the water reservoir  88  is replenished with water from the water replenishment piston part  154 . However, in the state illustrated in  FIG. 16C , the support rack  144  does not support the water replenishment tank bottom  175 , so that the water replenishment pump unit  150  itself is moved down to prevent an action of the water replenishment piston part  154 . 
     As a result, water is not ejected from the water replenishment piston part  154  and, therefore, the water reservoir  88  is not replenished with water and is left empty. In this state, the pressure teeth  82  are brought into pressure contact with the sheets to crimp-bind the sheet bundle without water application. That is, as already described, the pinion gear  142  (pinion gear  142   b ) does not move the support rack  144  by the action of the one-way clutch  147 , so that the water replenishment piston part  154  is not operated. In the device disclosed herein, up to five sheets can be subjected to the crimp-binding without water application at a time. The reason for this will be described later. 
     Crimp-Binding with Water Application 
     The following describes the water application/crimp-binding in which water is applied to the crimping range before crimping operation of the pressure teeth  82  with reference to  FIGS. 17A to 19C .  FIGS. 17A to 17C  are views illustrating the binding unit  60  as viewed from the front side,  FIGS. 18A to 18C  are views of the binding unit  60  as viewed from the rear side, and  FIGS. 19A to 19C  are cross-sectional views for explaining the water application/crimp-binding.  FIGS. 17A, 18A, and 19A  illustrate a state where the pressure teeth support part  84  (pressure teeth  82 ) is separated from sheets,  FIGS. 17B, 18B, and 19B  illustrate a state where the pressure teeth support part  84  is brought into pressure contact with sheets, and  FIGS. 17C, 18C, and 19C  illustrate a state where sheets are crimped with water application. 
       FIGS. 17A, 18A, and 19A  illustrate a sheet receiving stage. Sheets are placed on the processing tray  58 . More specifically, the sheets are placed on the receiving teeth support part  128  and between the pressure teeth  82  and the receiving teeth  130  of the binding unit  60 . For descriptive convenience, the sheets are not illustrated in  FIGS. 17A to 18C  and illustrated in  FIGS. 19A to 19C . When the specified number of sheets are loaded on the receiving teeth support part  128  provided with the receiving teeth  130 , the binding motor  60 M starts driving. In this case, since water application is performed, the binding motor  60 M is rotated in the direction opposite to the direction illustrated in  FIGS. 14A to 16C  in which the sheets are crimp-bound without water application. The number of sheets placed in this case is larger than five (eight in the device disclosed herein). 
     That is, in this case, water application is performed, so that the binding motor  60 M is driven in a direction to turn the moving cam  145  in the counterclockwise direction on the front side ( FIGS. 17A to 17C ) and turn the moving cam  145  in the clockwise direction on the rear side ( FIGS. 18A to 18C ). The moving cam  145  has a symmetric shape with respect to the rotation position, so that, also in this case, the protruding side of the moving cam  145  is moved in a direction to press down the leading end of the turning arm  134 . On the other hand, the pinion gear  142  (pinion gear  142   b ) engaged with the intermediate gear  138  is rotated to move the support rack  144  by the action of the one-way clutch  147  in such a direction that the support rack  144  supports the water replenishment tank bottom  175 . 
     That is, the support rack  144  mates with the one-way clutch  147  interposed between the pinion gear  142  (pinion gear  142   b ) and its shaft by one rotation direction (clockwise direction in  FIGS. 18A to 18C ) of the binding motor  60 M to move to a position at which it supports the water replenishment tank bottom  175 . As a result, the water replenishment tank bottom  175  is fixed, and when the water replenishment head part  156  is pressed by the pressing plate  102 , the water replenishment piston part  154  is operated, with the result that water in the water replenishment tank  174  is supplied to the water reservoir  88  through the water replenishment joint part  158 . As illustrated in  FIGS. 19A to 19C , a rack return spring  139  is interposed between the support rack  144  and the outer frame  120 . The rack return spring  139  is disengaged when the shaft thereof is reversely rotated to return the support rack  144  to its original position. 
     In the state illustrated in  FIGS. 17B, 18B, and 19B , the pressing plate  102  is moved down to bring the pressure teeth support part  84  having the pressure teeth  82  into close contact with the sheets. When the pressing plate  102  is pressurized in this state, the pressure teeth support part  84  is pressed against the sheets by the compression spring  96  interposed between the pressing plate  102  and the pressure teeth support part  84 . The elastic member (rubber plate)  92  that surrounds the pressure teeth  82  is provided in the pressure teeth support part  84  on the pressure teeth  82  side and is brought into pressure contact with the sheets so as not to generate a gap between the pressure teeth  82  and the sheet surface. In the device disclosed herein, a force of 70 kgf to 100 kgf is applied to the sheets. In this stage, water is retained in the water reservoir  88  by the operation of the water replenishment piston part  154 ; however, the piston  104  does not arrive at a position where pressurization occurs between itself and the cylinder  90 , so that water application by pressurization is not performed. 
     In the state illustrated in  FIGS. 17C, 18C, and 19C , the turning arm  134  is moved by the moving cam  145  in a state where the pressure teeth support part  84  is brought into close contact with the sheets to move down the pressing plate  102 . Then, the piston  104  inserted inside the cylinder  90  to apply water in the water reservoir  88  to the sheets through the water supply holes (water supply tubes)  86  formed in the pressure teeth  82 . After water application as well, the pressing plate  102  is moved by the moving cam  145  in a direction crimping the sheets, with the result that the piston  104  presses the pressure teeth  82  against the receiving teeth  130  to crimp the sheets. The pressurizing force in the crimp-binding with water application can be adjusted to be smaller than that in the crimp-binding without water application and is 300 kgf to 400 kgf. In the device disclosed herein, a voltage to the binding motor  60 M is controlled so as to generate a pressurizing force of 350 kgf. 
     As already described above, in the water replenishment pump unit  150 , the water replenishment head part  156  is pressed by the pressing plate  102  in a state where the water replenishment pump unit  150  is sandwiched between the pressing plate  102  and the support rack  144 , whereby the water reservoir  88  is replenished with water from the water replenishment piston part  154 . That is, as illustrated in detail in  FIGS. 19B and 19C , the support rack  144  supports the water replenishment tank bottom  175  from below, and the water replenishment pump unit  150  is fixed. As a result, water is ejected from the water replenishment piston part  154  and supplied to the water reservoir  88 . In the device disclosed herein, eight sheets are placed on the processing tray  58  and subjected to the water application/crimp-binding. 
     Pressure Teeth and Receiving Teeth of Water Application/Pressurizing Part 
     Hereinafter, the pressure teeth  82  and the receiving teeth  130  of the water application/pressurizing part  80  will be described using  FIGS. 20A to 20C , and a mating state between the pressure teeth  82  and the receiving teeth  130  and the position of the water supply holes (water supply tubes)  86  will be described using  FIG. 21 .  FIG. 20A  is a plan view of the pressure teeth  82 . As described above, the cylinder  90  that retains water to be applied to sheets is provided on the back side of the pressure teeth  82  (the side of the pressure teeth support part  84  opposite to the side at which the pressure teeth  82  bite the sheets). The cylinder  90  has a partially cut cylindrical shape and is constituted of a range (water reservoir  88 ) in which the piston  104  pressurizes water for water application, a piston insertion guide having a diameter larger than the water reservoir  88 , and a water replenishment port  118  through which water from the water replenishment pump unit  150  is received. 
       FIG. 20B  is a cross-sectional view of the pressure teeth  82  denoted by a chain double-dashed line in  FIG. 20A  and the receiving teeth part  126 . As is clear from  FIG. 20B , the pressure teeth support part  84  is integrally formed with the pressure teeth  82  and the cylinder  90  and guide bar  94  provided on the back side of the pressure teeth  82 . This ensures strength and easy assembly. The receiving teeth  130  (receiving teeth part  126 ) that mate with the pressure teeth  82  are provided at a position facing the pressure teeth support part  84 . Further, the drain pan  133  for receiving water (residual water) remaining at water application is disposed below the receiving teeth  130 . 
     Further, the water supply holes (water supply tubes)  86  for allowing water in the water reservoir  88  to be applied to the sheets are formed in the respective slopes of the pressure teeth  82 . Further, communication holes  132  are formed in the respective slopes of the receiving teeth  130 . Through the communication holes  132 , air pushed at the time of sheet pressing by the pressure teeth support part  84  and water remaining at water application are made to pass outside the receiving teeth  130 . The communication holes  132  have a larger capacity than that of the water supply holes (water supply tubes)  86 , whereby air and water can be effectively discharged. 
       FIG. 20C  illustrates the pressure teeth support part  84  as viewed from the bottom (pressure teeth  82  side) thereof. As illustrated, the elastic member  92  made of a rubber material that surrounds the pressure teeth  82  is bonded to the pressure teeth support part  84 . This can eliminate a gap around the pressure teeth  82  in a process that the pressure teeth support part  84  is pressed against the sheets by the compression spring  96 , thereby suppressing water applied outside the crimping/pressurization area from spreading. 
     Arrangement of Water Supply Holes (Water Supply Tubes) and Communication Holes 
     The following describes the water supply holes (water supply tubes)  86  formed in the pressure teeth  82  ( FIGS. 20A to 20C ) and the communication holes  132  ( FIG. 20B ) formed in the receiving teeth  130  so as to communicate with the outside (drain pan  133 ) using  FIG. 21 .  FIG. 21  is an enlarged view for explaining the pressure teeth  82  and the receiving teeth  130 . The pressure teeth  82  include ridges  82   a , valleys  82   b , and slopes  82   c  connecting the ridges  82   a  and valleys  82   b . Similarly, the receiving teeth  130  include receiving ridges  130   a , receiving valleys  130   b , and receiving slopes  130   c . Thus configured pressure teeth  82  and receiving teeth  130  mate with each other to make the sheet bundle partially form ridges and valleys, thereby facilitating mutual entanglement of the fibers of the sheets. 
     Water in the water reservoir  88  inside the cylinder  90  is ejected through the water supply holes (water supply tubes)  86  formed in the pressure teeth  82  by pressing of the piston  104 . At this time, the water is ejected from the plurality of slopes  82   c  as illustrated. It is confirmed that, as illustrated in the chain double-dashed circle of  FIG. 21 , when the pressure teeth  82  and the receiving teeth  130  mate with each other so as to make the sheets form ridges and valleys, fibers (in the case of a paper material, cellulose fibers) of the sheets are unfolded to a higher degree in the slopes  82   c  and receiving slopes  130   c  (indicated by the opposing arrows in  FIG. 21 ). 
     When water is applied to the slope where fibers are unfolded to the highest degree, the water is easily permeated into the sheet, facilitating mutual entanglement of the fibers by subsequent pressurization and so-called hydrogen bond. Thus, in the disclosed invention, the water supply holes (water supply tubes)  86  are formed in the respective slopes  82   c  of the pressure teeth  82 . Further, as described above, the communication holes  132  having a larger capacity than that of the water supply holes (water supply tubes)  86  are formed in the respective receiving slopes  130   c  of the receiving teeth  130  so as to facilitate discharge of air and water therethrough. 
     Pressure Teeth Support Part and Receiving Teeth Support Part 
     The following describes the relationship between the positions of the pressure teeth support part  84  and receiving teeth support part  128  and the position of the sheets held and pressed between the pressure teeth support part  84  and the receiving teeth support part  128  with reference to  FIG. 22  and  FIGS. 23A to 23C .  FIG. 22  illustrates the position of the sheet bundle to be subjected to the crimp-binding at the corner thereof on the front side of the processing tray  58  (see  FIG. 3 ). In the device disclosed herein, when the sheet bundle is crimped at the corner thereof, the sheet position is regulated such that the pressure teeth support part  84  that crimps the sheet bundle with the pressure teeth  82  and the receiving teeth support part  128  that supports the receiving teeth  130  mating with the pressure teeth  82  protrude from the apex of the corner of the sheet bundle by a dimension of L 3 . That is, the end of both the support parts  84  and  128  on the side far from the gravity center of the sheet bundle protrude from the apex of the corner of the sheet bundle by a dimension of L 3 . On the other hand, the ends of both the support parts  84  and  128  on the side close to the gravity center of the sheet bundle is separated from the water permeation area by a dimension of L 2 . That is, pressing is performed including an area where water is not applied, i.e., where the applied water is not permeated (area with a dimension of L 2  extending from the end of a position where the water ejected from the pressure teeth  82  is permeated toward the gravity center of the sheet bundle). 
       FIG. 23A  is a cross-section taken along the line Sc of  FIG. 22 . As is clear from  FIG. 23A , the pressing area of the support part  84  and the receiving teeth support part  128  includes the water application area L 1  as substantially the center of the pressing area, the area protruding from the apex of the corner of the sheet bundle by a dimension of L 3 , and area extending toward the gravity center of the sheet bundle from the water application area L 1  by a dimension of L 2 . 
     In the configuration illustrated in  FIG. 23B , the water application range exceeds the sheet pressing range by a dimension of L 2  toward the sheet gravity center side. Thus, fibers of the sheets remain unfolded due to water application, and the sheet may be easily torn at a position near the pressure teeth  82  on the sheet gravity center side. Further, when the sheet bundle is left as it is without being pressed, the water application range on the sheet surface is wrinkled, degrading the appearance. Thus, by adopting the configuration as illustrated in  FIG. 23A  in which the pressing range includes the outside of the water application range, the sheets become less likely to be torn. 
     Further, in the configuration illustrated in  FIG. 23C , the water application area L 1  is larger than the sheet pressing region L 4 , and the corner of the sheet bundle protrudes outward from the pressing position by a diameter of L 5 . In this case, water is applied to a portion that is not pressed, so that, particularly, the corner positions of the respective sheets are liable to be varied vertically. Thus, by adopting the configuration as illustrated in  FIG. 23A  in which the pressing area includes the end portion of the sheet bundle, the water application position is pressed to prevent the positional variation, and the appearance is improved. 
     In the above description, the front side (see  FIG. 3 ) of the processing tray  58  is taken as an example. Similarly, on the rear side as well, by adopting the configuration in which the pressing area includes a portion exceeding the sheet corner on the side far from the gravity center of the sheet bundle and a portion exceeding the water application position on the side close to the gravity center of the sheet bundle, the same effects can be obtained. 
     The following describes, using  FIGS. 24A to 24D , a predetermined number of sheets based on which one of the crimp-binding without water application and the water application/crimp-binding, which have been described using  FIGS. 14A to 19C , is performed and the number of sheets to be subjected to crimping and water application. 
       FIG. 24A  is a schematic view for explaining the relationship between the pair of teeth (pressure teeth  82  as the upper-side teeth and receiving teeth  130  as the lower-side teeth) and the predetermined number of sheets. As illustrated, the ridges and valleys of the sheets are formed by a height difference 1 h between the upper- and lower-side teeth, in other words, a distance between the apex of the ridge  82   a  and the bottom of the valley  82   b . Generally, the height difference is set to 0.4 mm to 0.6 mm. In the case of the pressure teeth  82  and the receiving teeth  130  in the disclosed invention, the height difference is set to 0.5 mm. 
     A sheet used as a normal copying paper has a basis weight of 68 g/cm 2  and a thickness 1 p of about 0.1 mm. That is, five sheets are suitable for formation of the ridges and valleys, and when the predetermined number of sheets exceeds five, the crimping strength between the sheets becomes weak. Thus, the predetermined number of sheets to be subjected to the crimp-binding without water application in the water-application/crimp-binding unit  60  disclosed herein is set to five, and when the number of sheets exceeds five, the water application/crimp-binding is performed so as to once unfold the fibers of the sheets. Therefore, when the height difference between the upper- and lower-side teeth is 0.6 mm, the predetermined number of sheets is six, and when the height difference between the upper- and lower-side teeth is 0.4 mm, the predetermined number of sheets is four. 
     The following describes, using  FIGS. 24B to 24D , patterns of the water application and crimping in the water application/crimp-binding when the sheets (in this case, three sheets are added, and thus eight sheets in total) whose number exceeds the predetermined number of sheets (five, in this case) are placed on the processing tray  58 . The wavy line in the drawing represents a state where the sheets are pressed by the pressure teeth  82  and the partially added straight line represents a water-applied sheet. 
     Water Application and Crimping for Each of Added Sheets 
     In  FIG. 24B , for each of the added three sheets, the water reservoir  88  provided on the back side of the pressure teeth  82  is replenished with water, followed by pressurization with the pressure teeth  82 . The pressurization may be performed once at the timing at which the number of sheets reaches the predetermined number of sheets (five); however, this is not performed in the device disclosed herein, and water application and crimping are repeated for each of added sheets. With this configuration, sheets whose number exceeds the predetermined number can be crimp-bound. As described above, whether or not to perform the water application is switched depending on the rotation direction of the binding motor  60 M. 
     Water Application for Each of Added Sheets and Pressurization after Placement of Last Sheet (After Accumulation of Certain Number of Added Sheets) 
     In  FIG. 24C , only the water application from the water reservoir  88  is performed for each of the added three sheets, and both the water application and pressurization by the pressure teeth  82  are performed after placement of the last sheet. Like the above pattern, the pressurization is not performed at the timing at which the number of sheets reaches the predetermined number of sheets (five), and water application is repeated for each of added sheets. With this configuration, the sheets whose number exceeds the predetermined number can be crimp-bound. The water application to be performed alone is set based on the rotation direction and the rotation range of the binding motor  60 M. Further, a pattern may be adopted, in which only the water application is performed for each addition, and pressurization is performed at the timing at which the number of added sheets reaches a certain number. 
     Water Application and Pressurization after Placement of Last Sheet (After Accumulation of Certain Number of Added Sheets 
     In  FIG. 24D , water in the water reservoir  88  is applied and, at the same time, pressurization by the pressure teeth  82  is performed at the stage when three sheets are added and thus a total of eight sheets are placed on the processing tray  58 . In the device disclosed herein, the water in the water reservoir  88  is pressurized at a considerably high pressure by the piston  104 , so that water is easily permeated into bundled sheets. 
     With this configuration, sheets whose number exceeds the predetermined number can be crimp-bound. The pressurization may be performed once at the timing at which the number of sheets reaches the predetermined number (five); however, this is not performed in the device disclosed herein, and water application and crimping are performed after placement of the last sheet. When a large number of sheets are accumulated until the last sheet is placed, the water application and pressurization may be performed at the timing at which the number of added sheets reaches a certain number. 
     Removal of Water Replenishment Pump Unit 
       FIG. 25  illustrates a state where the water replenishment pump unit  150  is removed from the binding unit  60 . As illustrated, a bottom frame  194  is turned about a frame turning shaft  196  provided in the outer frame  120  of the binding unit  60  to thereby remove the water replenishment pump unit  150  through a pump holding cover  192 . Then, the tank cap  172  is removed from the water replenishment tank  174  and is replenished with water.  FIG. 25  illustrates a state where the bottom frame  194  is turned downward; however, the pump holding cover  192  may be openably slid so as to allow the water replenishment pump unit  150  to be removed in the direction of the arrow in the drawing. 
     Control Configuration 
     The control configuration of the image forming device A disclosed herein will be described using the block diagram of  FIG. 26 . The image forming device A of  FIG. 1  has an image forming control section  200  of the image forming main body A 1  and a sheet processing control section  205  (control CPU) of the sheet processing device B. The image forming control section  200  has a sheet supply control section  202  and an input section  203 . On a control panel  26  provided in the input section  203 , an operator can set the following modes: (1) printout mode; (2) jog sorting mode; (3) binding mode; (4) book-binding (saddle-stitching) mode; and (5) manual binding mode. Details of the above modes will be described later. 
     The sheet processing control section  205  is a control CPU that operates the sheet processing device B according to a sheet processing mode designated from among the above five modes. The sheet processing control section  205  has a ROM  207  that stores an operation program and a RAM  206  that stores control data. Further, the sheet processing control section  205  acquires detection information from a sensor input section  220 . 
     Sensor Input Section 
     The sensor input section  220  has an entrance sensor  38  for detecting carry-in of an image-formed sheet from the image forming main body A 1  and detects the front and rear ends of the sheet to thereby manage drive of motors. A sheet sensor  39  for detecting sheet jamming and the like is provided downstream of the entrance sensor  38 . Further, the processing tray  58  is provided with a processing tray empty sensor  58 S for detecting whether a sheet is present on the processing tray  58 . Further, a loading tray position sensor  34 S for detecting the surface of the loading tray  34  that accumulates thereon the sheet discharged by the sheet discharge roller  52  while being gradually lowered is provided. In addition, there are provided a sensor for the punch unit  40 , a sensor for detecting the position of the binding unit  60 , and a sensor for detecting the operation of the saddle-stitching unit  66  (descriptions thereof are omitted here). 
     Output Section (Motors) 
     The sheet processing control section  205  includes a conveyance control section  210  that controls sheet conveyance. The conveyance control section  210  controls a carry-in roller motor  41 M for sheet carry-in operation and a conveying roller motor  48 M for conveying a sheet to the processing tray  58 . 
     Further, a punch control section  211  is provided for punching the rear end of a sheet carried in by the carry-in roller  41 . The punch control section  211  controls a punch motor that punches a sheet at a designated position in the sheet width direction. Further, a processing tray control section  212  controls an aligning plate motor  59 M that moves the aligning plates  59  that sandwich a sheet carried out to the processing tray  58  from both sides in the sheet width direction for alignment. 
     A binding control section  213  controls the above-described binding motor  60 M and a binding unit moving motor  60 SM for moving the binding unit  60  to a designated position in the sheet width direction so as to achieve two-point binding or corner binding. A sheet bundle thus bound is discharged to the loading tray  34  by a bundle moving belt (not illustrated) and the sheet discharge roller  52 . 
     At this time, a loading tray motor  34 M is controlled by a tray lifting control section  214  based on detection made by a loading tray position sensor  34 S so as to keep the position of the upper surface of the sheet bundle with respect to the sheet discharge port  54  constant at all times. In addition, there are provided a stacker control section  215  and a folding/discharge control section  217  for bookbinding (saddle-stitching); however, these control sections are not directly related to the present disclosure, so descriptions thereof are omitted here. 
     Sheet Processing Mode 
     The sheet processing device B is a device that receives, through the entrance  36 , a sheet carried out from the sheet discharge port  16  of the image forming main body A 1  and processes the received sheet. The sheet processing device B has the following five processing modes: (1) printout mode in which image-formed sheets are loaded/stored; (2) jog sorting mode in which image-formed sheets are aligned and stored; (3) binding mode in which image-formed sheets are aligned, accumulated, and bound; (4) bookbinding (saddle-stitching) mode in which image-formed sheets are aligned, accumulated, and bound, and then folded into a booklet; and (5) manual binding mode in which a sheet bundle inserted into a manual insertion slit  35  is bound for each insertion. 
     The above binding mode and manual binding mode each have a water application/crimp-binding mode in which sheets are bound after water application to the binding position and a non-water application/crimp-binding mode in which sheets are bound without water application. In the device disclosed herein, the above modes are set based on sheet number information acquired from the image forming main body. 
     A determination section that determines whether or not the number of sheets to be bound is equal to or less than the predetermined number may acquire determination information from the sheet processing control section (control CPU)  205  or image forming control section. Further, the thickness of a sheet bundle to be pressurized between the pressure teeth  82  and the receiving teeth  130  may be measured by a known method and converted into the number of sheets. 
     The following describes modifications partially different from the above-described embodiment. Modifications 1 to 3 will be described using  FIG. 27 ,  FIG. 28 , and  FIG. 29 , respectively. In these modifications, the same reference numerals are given to the same or similar constituent elements to those of the above embodiment. 
     Modification 1—Combined Use with Stapling Unit  60 SP 
       FIG. 27  illustrates a modification of the configuration illustrated in  FIG. 3 , in which the water application/crimp-binding unit  60  and a stapling unit  60 SP having a known mechanism are used in combination. More specifically, the front-side corner binding of a sheet bundle and manual binding of a sheet bundle are performed by the water application/crimp-binding unit  60 . In the manual binding in this case, a sheet bundle is inserted into the processing tray  58 , and the water application/crimp-binding is performed with the aligning plate  59  moved to a manual insertion position to guide a sheet bundle and with the reference stopper  62  moved to the position denoted by the dashed lines at the sheet bundle front side. This eliminates wasteful use of stapler needles when a sheet bundle constituted by a small number of sheets is bound, which is environmentally friendly. 
     Modification 2—Positional Change of Water Supply Holes (Water Supply Tubes) 
     In the modification 2 illustrated in  FIGS. 28A to 28C , the positions of the plurality of water supply holes (water supply tubes)  86  formed in the slopes  82   c  of the pressure teeth  82  (see particularly  FIGS. 20A to 20C  and  FIG. 21 ) are changed. In the example of  FIG. 28A , the water supply holes (water supply tubes)  86  are formed in the respective ridges  82   a  of the pressure teeth  82 . In this case as well, water can effectively be applied to the binding position. Further, in the receiving teeth  130 , the communication holes  132  communicating with the outside are formed in the respective receiving valleys  130   b  for discharge of air and residual water. 
     In the example of  FIG. 28B , the water supply holes (water supply tubes)  86  are formed in the respective ridges  82   a  of the pressure teeth  82  like the above example, and the communication holes  132  of the receiving teeth  130  are cut larger into a substantially square shape in cross section. This allows effective discharge of air and residual water. 
     In the example of  FIG. 28C , the water supply holes (water supply tubes)  86  are formed in the respective ridges  82   a  of the pressure teeth  82  like the above examples, and the communication holes  132  are formed in the respective receiving ridges  130   a  of the receiving teeth  130 . This increases the mating accuracy to increase the crimping force and allows discharge of air and water. 
     Modification 3—Installation of Extension Tank 
       FIGS. 29A and 29B  are explanatory views illustrating a configuration in which an extension tank  184  for increasing the capacity of the water replenishment tank  174  of the water replenishment tank part  152  of  FIG. 10  is additionally installed.  FIG. 29A  illustrates a state where the extension tank  184  is substantially filled with water, and  FIG. 29B  illustrates a state where the amount of water in the extension tank  184  is reduced. 
     As illustrated, a connection pipe  180  of the water replenishment tank  174  and an extension pipe  186  of the extension tank  184  are connected at a connection part  190 . Thus, when the amount of water in the water replenishment tank  174  is reduced, water can be supplied to the water replenishment tank  174  through the connection pipe  180  and the extension pipe  186 . 
     A tank manual valve  182  for stopping or releasing the water flow is provided in the connection pipe  180 , and an extension tank manual valve  188  having the same function as that of the tank manual valve  182  is provided in the extension pipe  186 . Thus, the extension tank  184  can be separated from the water replenishment tank  174  as needed for water replenishment. 
     Further, a bellows part  183  is provided at the entrance of the connection pipe  180  fitted to the bottom of the water replenishment tank  174  so as to allow vertical movement of the water replenishment pump unit  150 , enabling operation of the water replenishment piston part  154  in the binding unit  60 . In this case, the moving plate  176  vertically moved with a reduction in the amount of water is provided in the extension tank  184 , and the air hole  178  described above is formed in an upper lid  179 . Thus, according to the modification 3, water application can be performed more frequently without increasing the capacity of the water replenishment pump unit  150 . Further, the extension tank  184  can be separated from the water replenishment tank  174 , thus facilitating water replenishment operation. 
     It should be appreciated that the present invention is not limited to the above embodiment, and various modifications may be made. Further, all technical matters included in the technical ideas set forth in the claims should be covered by the present invention. While the invention has been described based on a preferred embodiment, various substitutions, corrections, modifications, or improvements may be made from the content disclosed in the specification by a person skilled in the art, which are included in the scope defined by the appended claims.