Patent Publication Number: US-10331072-B2

Title: Printing system with creasing control, control method thereof, control apparatus, and non-transitory computer-readable storage medium

Description:
This is a continuation of U.S. patent application Ser. No. 15/427,180, filed Feb. 8, 2017, which is a continuation of U.S. patent application Ser. No. 14/614,438, filed Feb. 5, 2015, now U.S. Pat. No. 9,604,488. 
    
    
     BACKGROUND OF THE INVENTION 
     Field of the Invention 
     The present invention relates to a printing system, a control method thereof, a control apparatus, and a non-transitory computer-readable storage medium and, more particularly, to a method of making a crease at a pressure corresponding to the creasing purpose when performing creasing. 
     Description of the Related Art 
     Recently, it is becoming popular to perform crease processing on a printed material bound by case binding or the like, or a printing sheet to undergo fold processing (to be referred to as a “medium” hereinafter) by using an image forming apparatus such as a digital multi-function peripheral. Creasing is processing of making a crease on a medium before performing fold processing. For example, in case binding, creases are made at the edges of a case binding spine so that the folds at the edges of the spine can look fine, improving the quality of the bound printed material. A crease made at a fold position will be called a “crease for a spine edge (crease for a fold)”. 
     Creasing is also used to prompt the user to make a crease in advance at a position where a fold is to be made. For example, case binding often uses a thick medium as a cover. By making a crease on a cover in advance, the user can easily open the cover. When a cover and inner sheets are glued in case binding, a force is applied to the gluing position at the time of opening the cover, and the cover may readily come unstuck. To prevent this, a crease is made at a location spaced apart from the gluing position so that no force is applied to the gluing position even when the user opens the cover. A crease made at a position where the user is requested to make a fold will be called a “crease for a hinge”. 
     Although the “crease for a spine edge (crease for a fold)” and the “crease for a hinge” are made by crease processing that is performed on one medium, an appropriate pressure at which a creasing blade is pressed when forming each crease is different. For example, when a sheet having a grammage of 250 gsm to 300 gsm is used as a case binding cover, it is desirable to make a fold at a high pressure so that the user can easily fold back the cover. In this case, the pressure for the “crease for a hinge” is preferably about 140 Kgf. To the contrary, for the “crease for a spine edge (crease for a fold)”, a crease is made at a fold position in advance before fold processing, improving the fold quality. At this time, if a fold for the “crease for a spine edge (crease for a fold)” is made at the same pressure as that for the “crease for a hinge”, a creasing trace remains remarkable, degrading the fold quality. To prevent this, the pressure for the “crease for a spine edge (crease for a fold)” is preferably about 70 to 120 Kgf, which is lower than the pressure for the “crease for a hinge”. 
     In a method disclosed in Japanese Patent Laid-Open No. 2012-126472, a crease target medium is creased at a pressure force corresponding to the medium by adjusting, based on sheet information of the target medium, the pressure force of a driving unit that performs crease processing. The method disclosed in Japanese Patent Laid-Open No. 2012-126472 makes a crease based on sheet information of a medium and can perform crease processing at a pressure corresponding to the medium. 
     In Japanese Patent Laid-Open No. 2012-126472, crease processing is performed at the same pressure for the same medium. Hence, when a single medium is creased a plurality of times, the pressure cannot be controlled in accordance with creasing purposes such as the “crease for a spine edge (crease for a fold)” and the “crease for a hinge”. 
     The present invention has been made to solve the above-described problems, and provides a method capable of changing the creasing pressure even for a single medium in accordance with each creasing purpose by executing creasing at a pressure corresponding to the creasing purpose. 
     SUMMARY OF THE INVENTION 
     According to one aspect of the present invention, there is provided a printing system comprising: a printing unit configured to print an image on a sheet; and a control unit configured to control to perform creasing at a first pressure at a portion, corresponding to an edge of a spine cover, of the sheet on which the printing unit has printed the image, and perform creasing at a second pressure different from the first pressure at a portion of the sheet that corresponds to a hinge. 
     According to another aspect of the present invention, there is provided a printing system comprising: a printing unit configured to print an image on a sheet; and a control unit configured to control to perform creasing at a first pressure at a portion, corresponding to an edge of a spine cover, of the sheet on which the printing unit has printed the image, and perform creasing at a second pressure larger than the first pressure at a portion of the sheet that corresponds to a hinge. 
     According to another aspect of the present invention, there is provided a control apparatus comprising: a first control unit configured to control to perform creasing at a first pressure at a portion of a sheet that corresponds to an edge of a spine cover, and a second control unit configured to control to perform creasing at a second pressure different from the first pressure at a portion of the sheet that corresponds to a hinge. 
     According to another aspect of the present invention, there is provided a printing system control method comprising: printing an image on a sheet; and controlling to perform creasing at a first pressure at a portion, corresponding to an edge of a spine cover, of the sheet on which the image has been printed in the printing step, and perform creasing at a second pressure different from the first pressure at a portion of the sheet that corresponds to a hinge. 
     According to another aspect of the present invention, there is provided a non-transitory computer-readable storage medium storing a program for causing a computer to execute a printing system control method, the printing system control method including: printing an image on a sheet; and controlling to perform creasing at a first pressure at a portion, corresponding to an edge of a spine cover, of the sheet on which the image has been printed in the printing step, and perform creasing at a second pressure different from the first pressure at a portion of the sheet that corresponds to a hinge. 
     According to the present invention, a crease can be made on a single medium in accordance with a purpose. 
     Further features of the present invention will become apparent from the following description of exemplary embodiments (with reference to the attached drawings). 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIGS. 1A and 1B  are views respectively showing an example of the arrangements of a system and image forming apparatus; 
         FIGS. 2A and 2B  are sectional views respectively showing an external feeding apparatus and an image forming apparatus main body; 
         FIGS. 3A and 3B  are sectional views respectively showing the image forming apparatus main body and an inserter; 
         FIG. 4  is a sectional view showing a creaser apparatus according to the first embodiment; 
         FIGS. 5A and 5B  are views respectively for explaining the section of a sheet folding apparatus and the formed shape of a medium; 
         FIGS. 6A and 6B  are sectional views respectively showing a case binding apparatus and a finisher apparatus; 
         FIGS. 7A, 7B, and 7C  are block diagrams respectively showing an example of the hardware arrangements of the image forming apparatus, the creaser apparatus, and an information processing apparatus; 
         FIG. 8  is a block diagram showing an example of the software arrangements of the image forming apparatus and information processing apparatus; 
         FIGS. 9A, 9B, 9C, and 9D  are views each showing an example of a job setting window; 
         FIGS. 10A, 10B, and 10C  are views respectively showing a hinge position in case binding, and the relationship between crease positions on a cover; 
         FIG. 11  is a table showing an example of the arrangement of a creasing pressure management table; 
         FIG. 12  is a flowchart showing processing by an image processing apparatus according to the first embodiment; 
         FIG. 13  is a flowchart showing processing by an image forming apparatus according to the first embodiment; 
         FIG. 14  is a view showing an example of a job setting window (crease) according to the second embodiment; 
         FIGS. 15A and 15B  are flowcharts showing processing by an image processing apparatus according to the second embodiment; 
         FIG. 16  is a flowchart showing processing by an image forming apparatus according to the second embodiment; 
         FIG. 17  is a sectional view showing a creaser apparatus according to the third embodiment; 
         FIGS. 18A and 18B  are views each showing an example of a display message according to the third embodiment; 
         FIG. 19  is a flowchart showing processing by an image forming apparatus according to the third embodiment; 
         FIG. 20  is a sectional view showing a creaser apparatus according to the fourth embodiment; 
         FIG. 21  is a view showing an example of a display message according to the fourth embodiment; and 
         FIG. 22  is a flowchart showing processing by an image forming apparatus according to the fourth embodiment. 
     
    
    
     DESCRIPTION OF THE EMBODIMENTS 
     Embodiments of the present invention will now be described with reference to the accompanying drawings. Note that the following embodiments are not intended to limit an invention defined by the scope of the appended claims. 
     [System Arrangement] 
     An example of the arrangement of an image forming system according to the embodiment will be explained with reference to the accompanying drawings. 
     The image forming system shown in  FIG. 1A  includes an image forming apparatus  101 , an image processing apparatus  102 , an information processing apparatus  103 , and a network  104 . The information processing apparatus  103  is an apparatus that is used by an operator to perform processing such as print job setting. The image processing apparatus  102  performs processing including generation of a print job, job management, RIP (Raster Image Processing), and imposition, and performs printing by using the image forming apparatus  101 . The network  104  connects the image forming apparatus  101 , the image processing apparatus  102 , and the information processing apparatus  103  so that they can communicate with each other. 
       FIG. 1B  is a view showing an example of the arrangement of the image forming apparatus  101 . The image forming apparatus  101  is constituted by an external feeding apparatus  201 , an external feeding apparatus  202 , an image forming apparatus main body  203 , an inserter apparatus  204 , a creaser apparatus  205 , a sheet folding apparatus  206 , a case binding apparatus  207 , and a finisher apparatus  208 . 
     The external feeding apparatuses  201  and  202  provide a large volume of media to the image forming apparatus main body  203 . The image forming apparatus main body  203  is a printing apparatus, and prints on media fed from the external feeding apparatuses  201  and  202  and a feeding tray accessory to the image forming apparatus main body  203 . The inserter apparatus  204  conveys a medium to the creaser apparatus  205 , the sheet folding apparatus  206 , the case binding apparatus  207 , and the finisher apparatus  208  without the mediacy of the image forming apparatus main body  203 . For example, the inserter apparatus  204  is used when a product such as a case-bound product is formed using, for example, pre-printed sheets having undergone printing once by the image forming apparatus main body  203 . The creaser apparatus  205  creases a medium. The sheet folding apparatus  206  performs fold forming processing such as Z-folding on a medium. The folding method is not particularly limited. The case binding apparatus  207  is an apparatus for generating a case-bound product. The finisher apparatus  208  performs finishing processing including punching and stapling, and generates a saddle-stitched product. 
       FIG. 2A  is a sectional view showing the external feeding apparatus  201  or  202 . A straight path  307  is a path for conveying downstream media conveyed from feeding trays  301 ,  302 , and  303  and an apparatus connected on the upstream side. In this embodiment, the external feeding apparatus  201  is arranged on the upstream side of the external feeding apparatus  202 , and the image forming apparatus main body  203  is arranged on the downstream side. The external feeding apparatus  202  conveys media stacked on the feeding trays  301 ,  302 , and  303 , and media conveyed from the external feeding apparatus  201  to the image forming apparatus main body  203  through the straight path  307 . 
     The feeding trays  301 ,  302 , and  303  are trays for feeding a medium. By lifting up the lower portions of the feeding trays using lift-up motors (not shown), fed media can be brought into contact with feeding motors  304 ,  305 , and  306 . This mechanism enables feeding regardless of the amount of media. The feeding motors  304 ,  305 , and  306  are motors that pick up media stacked on the feeding trays  301 ,  302 , and  303  one by one, respectively. Media stacked on the feeding trays  301 ,  302 , and  303  are supplied to conveyance paths by the feeding motors  304 ,  305 , and  306 , and conveyed to the straight path  307 . 
       FIGS. 2B and 3A  are sectional views showing the image forming apparatus main body  203 .  FIG. 2B  shows the arrangement of the upstream side of the image forming apparatus main body  203 .  FIG. 3A  shows the arrangement of the downstream side of the image forming apparatus main body  203 . Here, the upstream side is a side on which the image forming apparatus main body  203  is connected to the external feeding apparatus  202 , and the downstream side is a side on which it is connected to the inserter apparatus  204 . 
     Feeding trays  401  and  402  are trays for feeding a medium. By lifting up the lower portions of the feeding trays using lift-up motors (not shown), fed media can be brought into contact with feeding motors  403  and  404 . This mechanism enables feeding regardless of the amount of media. The feeding motors  403  and  404  are motors that pick up media stacked on the feeding trays  401  and  402  one by one, respectively. Media stacked on the feeding trays  401  and  402  are supplied to conveyance paths by the feeding motors  403  and  404 , and conveyed to a conveyance path  411 . A conveyance path  412  is a path for conveying a medium to a secondary transfer position  410 . The conveyance path  412  is connected to the straight path of the external feeding apparatus  202 . A medium conveyed from the conveyance path  411  and a medium conveyed from the straight path  307  of the external feeding apparatus  202  are conveyed through the conveyance path  412 . 
     Developing units  405 ,  406 ,  407 , and  408  are developing units for forming an image, and are constituted by stations of four Y, M, C, and K colors, respectively. Images formed by the developing units  405 ,  406 ,  407 , and  408  are primarily transferred onto an intermediate transfer belt  409  that rotates clockwise in  FIG. 2B . The resultant image is transferred at the secondary transfer position  410  onto a medium conveyed to the conveyance path  412 . 
     The medium on which the image has been transferred is conveyed to a first fixing unit  413  through the conveyance path  412  on the downstream side of the image forming apparatus main body  203  shown in  FIG. 3A . The first fixing unit  413  fixes the transferred image to the medium by heating and pressing the medium on which the image has been transferred. 
     A flapper  415  distributes a medium having passed through the first fixing unit  413  to a conveyance path  416  or a conveyance path  417 . The flapper  415  is constituted to be swingable about a swing shaft, and regulates the conveyance direction of a medium. When the flapper  415  is swung clockwise in  FIG. 3A , a medium is conveyed to the conveyance path  417 . When the flapper  415  is swung counterclockwise in  FIG. 3A , a medium is conveyed to the conveyance path  416 . Either the conveyance path  416  or  417  to which a medium having passed through the first fixing unit  413  is conveyed is decided depending on conditions such as the medium type (for example, grammage). If it is determined that an image needs to be fixed again, the medium is conveyed to the conveyance path  417 . If it is determined that an image need not be fixed again, the medium is conveyed to the conveyance path  416 . A second fixing unit  414  heats and presses a medium conveyed to the conveyance path  417 . 
     A discharge flapper  418  conveys, to the inserter apparatus  204  or a conveyance path  419 , a medium conveyed from the conveyance path  416  or  417 . The discharge flapper  418  is constituted to be swingable about a swing shaft, and regulates the conveyance direction of a medium. When the discharge flapper  418  is swung clockwise in  FIG. 3A , a medium is conveyed to the inserter apparatus  204 . When the discharge flapper  418  is swung counterclockwise in  FIG. 3A , a medium is conveyed to the conveyance path  419 . 
     A medium conveyed to the conveyance path  419  is conveyed to a reversing path  420 . The conveyance direction of the medium is changed by 180° by switchback processing. A flapper  421  is constituted to be swingable about a swing shaft, and regulates the conveyance direction of a medium. When the flapper  421  is swung clockwise in  FIG. 3A , a medium conveyed from the reversing path  420  is conveyed to a conveyance path  422 . The conveyance path  422  communicates with the conveyance path  411  on the upstream side of the image forming apparatus main body  203  shown in  FIG. 2B . Since the medium is reversed on the reversing path  420 , the printing surface of the medium in passing through the first fixing unit  413  and the second fixing unit  414  is turned over. With this mechanism, the image forming apparatus main body  203  executes double-sided printing. 
     When the flapper  421  is swung counterclockwise in  FIG. 3A , a medium passes through the conveyance path  419 . The discharge flapper  418  is then swung counterclockwise in  FIG. 3A , and the medium is conveyed to the inserter apparatus  204 . Since the medium has been reversed on the reversing path  420 , the medium can be conveyed to the inserter apparatus  204  with the fixed image facing down. Note that conveyance of a medium to the inserter apparatus  204  with a fixed image facing up can be implemented by not using the reversing path  420 . 
     An ADF (Auto Document Feeder)  423  is a document feeder for separating a document bundle set on the stacking surface of a document tray sequentially in the page order from a document of the first page, and scanning the document by a scanner  424 . The scanner  424  irradiates, with a light source (not shown), a document conveyed from the ADF  423 , and reads the document image by using a CCD (not shown). The read document image undergoes image processing, and a copy operation is executed using the developing units  405  to  408  shown in  FIG. 2B . 
     An operation panel  425  is an operation panel accessory to the image forming apparatus main body  203 , and is used to make settings in the image forming apparatus  101  and start the copy operation. 
       FIG. 3B  is a sectional view showing the inserter apparatus  204 . A straight path  501  is a path for conveying downstream a medium conveyed from the upstream side. In this embodiment, the inserter apparatus  204  conveys, to the creaser apparatus  205  through the straight path  501 , a medium received from the image forming apparatus main body  203 . 
     A conveyance path  502  is a conveyance path for conveying, to the straight path  501 , a medium fed to an inserter tray  503 . The inserter tray  503  is a tray for feeding, to the creaser apparatus  205 , the sheet folding apparatus  206 , the case binding apparatus  207 , or the finisher apparatus  208 , a medium not to undergo print processing by the image forming apparatus main body  203 . A sheet detection sensor  504  is a sensor that detects whether a medium has been fed to the inserter tray  503 . The inserter apparatus  204  includes a conveyance roller, and conveys, from the conveyance path  502  to the straight path  501 , a medium fed to the inserter tray  503 . The medium is conveyed to the downstream side through the straight path  501 . 
       FIG. 4  is a sectional view showing the creaser apparatus  205 . A straight path  601  is a path for conveying downstream a medium conveyed from the upstream side. In this embodiment, the creaser apparatus  205  conveys, to the sheet folding apparatus  206  through the straight path  601 , a medium received from the inserter apparatus  204 . 
     A conveyance path  602  is a conveyance path for conveying a medium to undergo crease processing. A flapper  603  distributes a medium conveyed from the inserter apparatus  204  to the straight path  601  or the conveyance path  602 . The flapper  603  is constituted to be swingable about a swing shaft, and regulates the conveyance direction of a medium. When the flapper  603  is swung clockwise in  FIG. 4 , a medium is conveyed to the straight path  601 . When the flapper  603  is swung counterclockwise in  FIG. 4 , a medium is conveyed to the conveyance path  602 . 
     A creasing die  604  is a die for performing crease processing on a medium, and includes a creasing blade  605  for performing creasing. Note that the creasing die  604  is detachable from the creaser apparatus  205 , and a sensor (not shown) can detect whether the creasing die  604  is attached in the creaser apparatus  205 . Further, the sensor (not shown) can uniquely recognize the type of attached die. Pressure devices  606 ,  607 , and  608  are devices for applying a pressure to the creasing die  604 . A base  609  is a base for receiving the creasing blade  605 . A conveyance speed control unit  610  controls the conveyance speed of a medium to a predetermined speed, and incorporates a sensor (not shown) for detecting the conveyance speed of a medium. A detection sensor  611  is a sensor for detecting the leading end of a conveyed medium. 
     Creasing of a medium by the creaser apparatus  205  is implemented by performing the following operation. First, based on the detection result of the sensor (not shown) for detecting the conveyance speed of a medium, the conveyance speed control unit  610  accelerates or decelerates a medium so that the conveyance speed of the medium passing through the conveyance path  602  becomes a predetermined speed. When the detection sensor  611  detects the leading end of the medium conveyed at the predetermined speed, the pressure devices  606  to  608  apply a pressure to the creasing die  604  downward from above it in  FIG. 4 . Note that only an arbitrary one of the pressure devices  606  to  608  can operate, or a plurality of devices can operate synchronously. The pressure devices  606  to  608  can control a pressure to be applied to the creasing die  604 . 
     The pressure applied to the creasing die  604  from the pressure devices  606  to  608  is transferred to the creasing blade  605 . The creasing blade  605  moves down from above a medium in  FIG. 4 , and the creasing blade  605  and the base  609  sandwich the medium, thereby implementing creasing. Note that the creaser apparatus  205  can make a crease at an arbitrary position of a medium in the conveyance direction. More specifically, creasing is implemented by performing the following control. 
     The conveyance speed control unit  610  controls a medium conveyed through the conveyance path  502  to a predetermined conveyance speed. The timing to perform creasing by the creasing blade  605  can be calculated by dividing, by a predetermined conveyance speed, a value obtained by adding a crease position (distance from the leading end of a medium) to the distance between the detection sensor  611  and the creasing blade  605 . That is, the pressure devices  606  to  608  are driven so that the creasing blade  605  contacts a medium at the calculated timing based on the timing when the detection sensor  611  detected the leading end of the medium. 
       FIG. 5A  is a sectional view showing the sheet folding apparatus  206 . A straight path  701  is a path for conveying downstream a medium conveyed from the upstream side. In this embodiment, the sheet folding apparatus  206  conveys, to the case binding apparatus  207  through the straight path  701 , a medium received from the creaser apparatus  205 . A conveyance path  702  is a conveyance path for conveying a medium to undergo fold processing. 
     A flapper  703  distributes a medium conveyed from the creaser apparatus  205  to the straight path  701  or the conveyance path  702 . The flapper  703  is constituted to be swingable about a swing shaft, and regulates the conveyance direction of a medium. When the flapper  703  is swung clockwise in  FIG. 5A , a medium is conveyed to the straight path  701 . When the flapper  703  is swung counterclockwise in  FIG. 5A , a medium is conveyed to the conveyance path  702 . A conveyance speed control unit  704  is a unit that controls the conveyance speed of a medium to a predetermined speed, and incorporates a sensor (not shown) for detecting the conveyance speed of a medium. 
     An abutment stopper  705  is used at the time of forming a C-fold. The abutment stopper  705  can be driven by a motor (not shown). The abutment stopper  705  can rotate counterclockwise from 0° to 90° in  FIG. 5A , and move up and down along the conveyance path  702 . First, the abutment stopper  705  is kept at a position in  FIG. 5A  by the rotational motion mechanism, and a medium can be conveyed from top to bottom on the conveyance path  702 . Then, the abutment stopper  705  is rotated counterclockwise by 90° and can close the conveyance path  702 . That is, the abutment stopper  705  functions as an abutment stopper for a medium conveyed through the conveyance path  702 . Further, the vertical motion mechanism along the conveyance path  702  can adjust the length from the abutment stopper  705  to a portion between folding rollers  710  and  711 . 
     A conveyance roller pair  706  is a conveyance roller pair for conveying up or down a medium conveyed through the conveyance path  702 . The rotational direction of the conveyance roller pair  706  can be controlled, and can be rotated in a direction in which a medium is pushed from top to bottom. The conveyance roller pair  706  can also be rotated in a direction in which a medium is pushed from bottom to top. 
     A conveyance path  707  is a conveyance path for drawing a medium at the time of forming a fold. A registration roller pair  708  is a roller pair for temporarily stopping a medium conveyed from the conveyance path  702  to the conveyance path  707 . Further, the registration roller pair  708  can convey a temporarily stopped medium in the up or down direction. The rotational direction of the registration roller pair  708  can be controlled, and can be rotated in a direction in which a medium is pushed from top to bottom. The registration roller pair  708  can also be rotated in a direction in which a medium is pushed from bottom to top. 
     A medium detection sensor  709  is a sensor for detecting the leading end of a medium temporarily stopped by the registration roller pair  708 . The folding roller  710 , the folding roller  711 , and a folding roller  712  are rollers used to form a fold. The folding rollers  710  to  712  are always driven simultaneously. At this time, the folding roller  710  rotates counterclockwise in  FIG. 5A , the folding roller  711  rotates clockwise in  FIG. 5A , and the folding roller  712  rotates counterclockwise in  FIG. 5A . 
     A leading end press guide  713  is a guide used to form a single fold. The leading end press guide  713  is used to guide, to a conveyance path  716 , a medium drawn from the folding rollers  710  and  711  without passing through a conveyance path  714 . The leading end press guide  713  can be driven by a motor (not shown). When a medium drawn from the folding roller  711  is not guided to the conveyance path  716 , the leading end press guide  713  is retracted from the position in  FIG. 5A . More specifically, when the leading end press guide  713  is retracted, the medium drawn from the folding rollers  710  and  711  is drawn to the conveyance path  714 . 
     The conveyance path  714  is a conveyance path for drawing a medium at the time of forming a fold. A portion, close to the top, of the conveyance path  714  in  FIG. 5A  has an arcuate shape so that the length by which a medium is drawn can be adjusted by an abutment stopper  715 . The abutment stopper  715  is an abutment stopper used at the time of forming a Z-fold, a 6-page accordion fold, a double parallel fold, or a C-fold. The abutment stopper  715  can be driven by a motor (not shown) and can rotate along the conveyance path  714 . The length by which a medium is drawn to the conveyance path  714  can be adjusted by adjusting the position of the abutment stopper  715 . 
     The conveyance path  716  is a path for conveying a medium having passed through the folding rollers  710  to  712 . Fold formation processing on the medium has been completed upon passing through the conveyance path  716 . A discharge portion  717  is used to discharge a C-folded or double parallel-folded medium. A conveyance path  718  is used to convey a folded medium to the straight path  701 . 
     A flapper  719  distributes a medium conveyed through the conveyance path  716  to the discharge portion  717  or the conveyance path  718 . The flapper  719  is constituted to be swingable about a swing shaft, and regulates the conveyance direction of a medium. When the flapper  719  is swung clockwise in  FIG. 5A , a medium is conveyed to the conveyance path  718 . When the flapper  719  is swung counterclockwise in  FIG. 5A , a medium is discharged to the discharge portion  717 . 
     Next, fold formation processing for each shape will be explained. First,  FIG. 5B  shows the shape of a fold when a medium passes through the conveyance path  718 . The sheet folding apparatus  206  conveys a medium to the straight path  701  when forming a Z-fold, a 6-page accordion fold, and a single fold, and discharges a medium to the discharge portion  717  when forming a double parallel fold and a C-fold. 
     Subsequently, a case in which the sheet folding apparatus  206  forms a Z-fold will be explained. A medium conveyed through the straight path  701  is conveyed to the conveyance path  702  by the flapper  703 . The conveyance speed control unit  704  controls the conveyance speed of the medium to a predetermined speed. At this time, the abutment stopper  705  exists at the position in  FIG. 5A . Thus, the medium is conveyed through the conveyance path  702  and moves until it is temporarily stopped by the registration roller pair  708 . The medium detection sensor  709  detects the leading end position of the medium temporarily stopped by the registration roller pair  708 . The medium is then drawn to the conveyance path  707  by the registration roller pair  708 . At this time, the length from the leading end of the drawn medium to a portion between the folding rollers  710  and  711  is controlled to be ¼ of the medium length. 
     When the conveyance roller pair  706  is kept controlled to convey the medium downward while the registration roller pair  708  stops the medium at that position, a loop of the medium is formed between the folding rollers  710  and  711 . The folding rollers  710  and  711  draw the looped portion, folding the medium at a ¼ portion from the leading end of the medium. 
     When forming a Z-fold, the leading end press guide  713  is controlled to be retracted, and the medium is drawn to the conveyance path  714 . At this time, the abutment stopper  715  is controlled so that the length up to a portion between the folding rollers  711  and  712  becomes ¼ of the medium length. By the folding rollers  710  and  711 , the medium drawn to the conveyance path  714  forms a loop at the center portion of the medium. The folding rollers  711  and  712  draw the looped portion, and the Z-folded medium is conveyed to the conveyance path  716 . After that, the flapper  719  is controlled to convey the medium to the conveyance path  718 , and the Z-folded medium is conveyed to the straight path  701 . 
     Subsequently, a case in which the sheet folding apparatus  206  forms a 6-page accordion fold will be explained. A process when the sheet folding apparatus  206  forms a 6-page accordion fold is almost the same as that when a Z-fold is formed. A 6-page accordion fold can be formed by setting the length by which a medium is drawn to the conveyance paths  707  and  714 , to be ⅓ of the medium length. The 6-page accordion fold formation process is almost the same as the Z-fold formation process, and a description thereof will not be repeated. 
     Subsequently, a case in which the sheet folding apparatus  206  forms a single fold will be explained. A medium conveyed through the straight path  701  is conveyed to the conveyance path  702  by the flapper  703 . The conveyance speed control unit  704  controls the conveyance speed of the medium to a predetermined speed. At this time, the abutment stopper  705  exists at the position in  FIG. 5A . Thus, the medium is conveyed through the conveyance path  702  and moves until it is temporarily stopped by the registration roller pair  708 . The medium detection sensor  709  detects the leading end position of the medium temporarily stopped by the registration roller pair  708 . The medium is then drawn to the conveyance path  707  by the registration roller pair  708 . At this time, the length from the leading end of the drawn medium to the portion between the folding rollers  710  and  711  is controlled to be ½ of the medium length. 
     When the conveyance roller pair  706  is kept controlled to convey the medium downward while the registration roller pair  708  stops the medium at that position, a loop of the medium is formed between the folding rollers  710  and  711 . The folding rollers  710  and  711  draw the looped portion, folding the medium at a ½ portion from the leading end of the medium. 
     When forming a single fold, the leading end press guide  713  exists at the position in  FIG. 5A . The medium drawn by the folding rollers  710  and  711  is conveyed to be drawn to the conveyance path  716  by the folding rollers  711  and  712 . In this manner, the single-folded medium is conveyed to the conveyance path  716 . The flapper  719  is controlled to convey the medium to the conveyance path  718 , and the single-folded medium is conveyed to the straight path  701 . 
     Subsequently, a case in which the sheet folding apparatus  206  forms a double parallel fold will be explained. A medium conveyed through the straight path  701  is conveyed to the conveyance path  702  by the flapper  703 . The conveyance speed control unit  704  controls the conveyance speed of the medium to a predetermined speed. At this time, the abutment stopper  705  exists at the position in  FIG. 5A . Thus, the medium is conveyed through the conveyance path  702  and moves until it is temporarily stopped by the registration roller pair  708 . The medium detection sensor  709  detects the leading end position of the medium temporarily stopped by the registration roller pair  708 . The medium is then drawn to the conveyance path  707  by the registration roller pair  708 . At this time, the length from the leading end of the drawn medium to the portion between the folding rollers  710  and  711  is controlled to be ½ of the medium length. 
     When the conveyance roller pair  706  is kept controlled to convey the medium downward while the registration roller pair  708  stops the medium at that position, a loop of the medium is formed between the folding rollers  710  and  711 . The folding rollers  710  and  711  draw the looped portion, at a ½ portion from the leading end of the medium. 
     When forming a double parallel fold, the leading end press guide  713  is controlled to be retracted, and the medium is drawn to the conveyance path  714 . At this time, the abutment stopper  715  is controlled so that the length up to the portion between the folding rollers  711  and  712  becomes ¼ of the medium length. By the folding rollers  710  and  711 , the medium drawn to the conveyance path  714  forms a loop at the center portion of the medium. The folding rollers  711  and  712  draw the looped portion, and the double parallel-folded medium is conveyed to the conveyance path  716 . After that, the flapper  719  is controlled to convey the medium to the discharge portion  717 , and the double parallel-folded medium is discharged to the discharge portion  717 . 
     Subsequently, a case in which the sheet folding apparatus  206  forms a C-fold will be explained. A medium conveyed through the straight path  701  is conveyed to the conveyance path  702  by the flapper  703 . The conveyance speed control unit  704  controls the conveyance speed of the medium to a predetermined speed. At this time, the abutment stopper  705  exists at the position in  FIG. 5A . Thus, the medium is conveyed through the conveyance path  702  and moves until it is temporarily stopped by the registration roller pair  708 . The medium detection sensor  709  detects the leading end position of the medium temporarily stopped by the registration roller pair  708 . The medium is then drawn to the conveyance path  707  by the registration roller pair  708 . At this time, the length from the leading end of the drawn medium to the portion between the folding rollers  710  and  711  is controlled to be equal to or larger than ⅔ of the medium length. 
     Then, the abutment stopper  705  is controlled counterclockwise in  FIG. 5A . Further, the abutment stopper  705  is adjusted so that the length on the conveyance path from the abutment stopper  705  to the portion between the folding rollers  710  and  711  becomes ⅓ of the medium length. After that, the registration roller pair  708  is controlled to convey upward the temporarily stopped medium. The medium abuts against the abutment stopper  705 , and a loop of the medium is formed between the folding rollers  710  and  711 . The folding rollers  710  and  711  draw the looped portion, folding the medium at a ⅓ portion from the trailing end of the medium. 
     When forming a C-fold, the leading end press guide  713  is retracted, and the medium is drawn to the conveyance path  714 . At this time, the abutment stopper  715  is controlled so that the length up to the portion between the folding rollers  711  and  712  becomes ⅓ of the medium length. By the folding rollers  710  and  711 , the medium drawn to the conveyance path  714  forms a loop at the center portion of the medium. The folding rollers  711  and  712  draw the looped portion, and the C-folded medium is conveyed to the conveyance path  716 . After that, the flapper  719  is controlled to convey the medium to the discharge portion  717 , and the C-folded medium is discharged to the discharge portion  717 . 
       FIG. 6A  is a sectional view showing the case binding apparatus  207 . A straight path  801  is a path for conveying downstream a medium conveyed from the upstream side. In this embodiment, the case binding apparatus  207  conveys, to the finisher apparatus  208  through the straight path  801 , a medium received from the sheet folding apparatus  206 . A conveyance path  802  is a conveyance path for conveying, to the straight path  801 , media fed to inserter trays  803  and  804 . The inserter trays  803  and  804  are trays for feeding a printed medium when a case-bound product is generated using printed media. 
     A flapper  805  distributes media conveyed from the sheet folding apparatus  206  and the inserter trays  803  and  804  to the straight path  801  or a conveyance path  806 . The flapper  805  is constituted to be swingable about a swing shaft, and regulates the conveyance direction of a medium. When the flapper  805  is swung clockwise in  FIG. 6A , a medium is conveyed to the straight path  801 . When the flapper  805  is swung counterclockwise in  FIG. 6A , a medium is conveyed to the conveyance path  806 . A conveyance speed control unit  807  includes a sensor (not shown) for detecting the leading end of a medium. The conveyance speed control unit  807  has a function of stopping conveyance of a medium after the sensor detects the leading end of the medium and the medium is conveyed by a predetermined distance. 
     A flapper  808  distributes a medium conveyed from the straight path  801  to the straight path  801  or a conveyance path  809 . The flapper  808  is constituted to be swingable about a swing shaft, and regulates the conveyance direction of a medium. When the flapper  808  is swung clockwise in  FIG. 6A , a medium is conveyed to the straight path  801 . When the flapper  808  is swung counterclockwise in  FIG. 6A , a medium is conveyed to the conveyance path  809 . The conveyance path  809  is a conveyance path for conveying a medium to a medium stacking unit  810 . 
     The medium stacking unit  810  is a unit for stacking case binding inner sheets. The medium stacking unit  810  has a U shape that is open on the front side, and has a function of moving from the front side to the back side. A gripper pair  811  grips an inner sheet bundle stacked in the medium stacking unit  810 , and after a gluing unit  812  glues the inner sheet bundle, conveys the inner sheet bundle to a formation roller pair  814 . The gluing unit  812  is a unit that dissolves glue for gluing a case binding inner sheet bundle and a case binding cover. The gluing unit  812  stores the dissolved glue in the unit during the operation of the case binding apparatus  207 , and has a function of moving from the front side to the back side. 
     A gluing table  813  is used when gluing an inner sheet bundle and cover to which the dissolved glue has been attached, and has a function of moving from the front side to the back side. The formation roller pair  814  is used to form the glued inner sheet bundle and cover into the shape of a case-bound product. The formation roller pair  814  rotates a roller pair in a direction in which a medium is pushed from top to bottom. The formation roller pair  814  receives the glued inner sheet bundle and cover from the gripper pair  811 , and drops the formed case-bound product to a turntable  818  along a guide  815  with the spine cover side of the case-bound product facing down. 
     The guide  815  is a guide for dropping the spine cover side of a formed case-bound product to face a widthwise alignment portion  816 . The widthwise alignment portion  816  is a device for adjusting the position in order to cut a formed case-bound product by a cutter  817 . The cutter  817  is a cutter for cutting the edge, top, and bottom of a formed case-bound product. The turntable  818  has a function of rotating a formed case-bound product, and makes it possible to cut the edge, top, and bottom of a case-bound product by only the cutter  817 . A basket portion  819  is a storage place for storing a cut case-bound product. 
     An operation when generating a case-bound product will be explained in detail below. A medium serving as a case binding cover is conveyed to the conveyance path  806  by the flapper  805 . The conveyance speed control unit  807  is controlled to stop the conveyance at a position where the center position of the medium serving as the case binding cover coincides with the center of a case binding spine cover. More specifically, the medium serving as the case binding cover is set on the gluing table  813 . 
     Then, a medium serving as a case binding inner sheet is conveyed to the straight path  801  by the flapper  805 , and conveyed to the medium stacking unit  810  through the conveyance path  809  by the flapper  808 . When an inner sheet bundle is completed, the gripper pair  811  grips the inner sheet bundle, and the medium stacking unit  810  moves from the front side to the back side. At this time, the gripper pair  811  is positioned in the U-shaped space of the medium stacking unit  810 . By moving the medium stacking unit  810  to the back side, the gripper pair  811  can move the inner sheet bundle to the gluing unit  812 . 
     While the gripper pair  811  rotates so that the spine cover direction of the inner sheet bundle faces down, it moves to the gluing unit  812  to perform gluing. Upon completion of gluing, the gripper pair  811  temporarily moves up the inner sheet bundle. Further, the gluing unit  812  is moved from the front side to the back side. Upon completion of the movement of the gluing unit  812 , the gripper pair  811  moves down and adheres the inner sheet bundle to the medium serving as the case binding cover set on the gluing table  813 . Upon completion of adhesion, the gluing table  813  moves from the front side to the back side. Upon completion of the movement, the gripper pair  811  moves down, and the formation roller pair  814  forms a case-bound product. 
     Subsequently, the formed case-bound product is pushed down to the formation roller pair  814  along the guide  815 , and is set on the turntable  818  with the spine cover side facing the widthwise alignment portion  816 . The formed case-bound product laid on the turntable  818  is aligned by the widthwise alignment portion  816 , and a portion serving as the edge is cut by the cutter  817 . The turntable  818  rotates by 90°, the case-bound product is aligned by the widthwise alignment portion  816 , and a portion serving as the top is cut. Further, the turntable  818  rotates by 180°, the case-bound product is aligned by the widthwise alignment portion  816 , and a portion serving as the bottom is cut. Finally, the cut case-bound product is pushed to the left in  FIG. 6A  by the widthwise alignment portion  816 , and dropped into the basket portion  819 . 
       FIG. 6B  is a sectional view showing the finisher apparatus  208 . A conveyance path  901  is a path for conveying a medium conveyed from the upstream side into the finisher apparatus  208 . In this embodiment, the finisher apparatus  208  conveys, into it, a medium received from the case binding apparatus  207 . A conveyance path  902  is a conveyance path for conveying, to the conveyance path  901 , media fed to inserter trays  903  and  904 . The inserter trays  903  and  904  are trays for feeding a printed medium when a punched, stapled, or saddle-stitched product is generated using printed media. 
     A flapper  905  is constituted to be swingable about a swing shaft, and regulates the conveyance direction of a medium conveyed through the conveyance path  901  or  902 . When the flapper  905  is swung counterclockwise in  FIG. 6B , a medium is conveyed to a conveyance path  906 . When the flapper  905  is swung clockwise in  FIG. 6B , a medium is conveyed to a conveyance path  907 . A flapper  908  is constituted to be swingable about a swing shaft, and regulates the conveyance direction of a medium conveyed through the conveyance path  907 . When the flapper  908  is swung counterclockwise in  FIG. 6B , a medium is conveyed to a conveyance path  910 . When the flapper  908  is swung clockwise in  FIG. 6B , a medium is conveyed to a conveyance path  909 . 
     The conveyance path  909  is a conveyance path for conveying a medium to a sample tray  911 . The conveyance path  910  is a conveyance path for conveying a medium to a stacking tray  914 . The sample tray  911  is a tray to which a medium having passed through the conveyance path  909  is discharged. A medium conveyed to the conveyance path  910  passes through a puncher  912  and a stapler  913 , and is conveyed to the stacking tray  914 . The puncher  912  is a device that performs punch processing on a medium passing through the conveyance path  910 . The puncher  912  includes a changeable blade (not shown) for two holes, three holes, or the like. By changing the blade, an arbitrary number of holes can be formed in a medium. 
     The stapler  913  is a device that stacks media passing through the conveyance path  910  and performs staple processing. The stapler  913  includes refillable staples (not shown), and can perform various staple processes such as corner stapling and two-position stapling. The stacking tray  914  is a tray to which a medium having passed through the conveyance path  910  is discharged. The conveyance path  906  is a conveyance path for conveying a medium when performing saddle stitch processing. 
     A stopper  915  is a stopper for stopping a medium conveyed from the conveyance path  906 . The stopper  915  can adjust the length from the stopper  915  to a folding plate  916  by a motor (not shown). In general, the length is set to ½ of the length, in the conveyance direction, of a medium to undergo saddle stitch processing. That is, saddle stitch processing is performed at the center of media to undergo saddle stitch processing. 
     The folding plate  916  is a device for pushing media stopped by the stopper  915  into a saddle stitcher  917 . The saddle stitcher  917  is a device that performs staple processing and fold processing on a medium pushed by the folding plate  916 . Media are folded at the center by the operations of the stopper  915  and folding plate  916 , and come into the saddle stitcher  917 . After the media pass through the saddle stitcher  917 , the media having undergone saddle stitch processing are conveyed to a stacking portion  918 . The media having undergone saddle stitch processing are discharged from the stacking portion  918  to a saddle tray  920  by an external discharge roller  919 . A guide  921  operates to store media having undergone saddle stitch processing and sequentially supply booklets one by one to a saddle stacking portion  922 . The saddle stacking portion  922  stores a large volume of media having undergone saddle stitch processing. 
     [Example of Hardware Arrangement] 
       FIG. 7A  is a block diagram showing an example of the hardware arrangement of the image forming apparatus  101 . A CPU circuit unit  1001  includes a CPU (Central Processing Unit)  1002 , and controls the following control units in accordance with programs stored in a ROM (Read Only Memory)  1003  serving as a storage unit. The CPU circuit unit  1001  controls an operation panel control unit  1005 , a document feeder control unit  1006 , an image reader control unit  1007 , an image signal control unit  1008 , a printer control unit  1009 , and a feeder control unit  1010 , which are control units regarding printing. The CPU circuit unit  1001  controls a creaser control unit  1011 , a sheet folding apparatus control unit  1012 , a case binding control unit  1013 , and a finisher control unit  1014 , which are control units regarding formation of a printed product. Further, the CPU circuit unit  1001  controls an HDD (Hard Disk Drive) I/F  1015  for controlling an HDD  1016 , and a network I/F  1017 , which are internal/external interface control units. A RAM (Random Access Memory)  1004  is a storage unit used as an area for temporarily holding control data, and a work area for calculation accompanying control. 
     The operation panel control unit  1005  controls the operation panel  425 . The document feeder control unit  1006  controls the ADF  423 . The image reader control unit  1007  controls the scanner  424 . The image signal control unit  1008  performs control of performing image processing on received image data, converting the image data into an image signal interpretable by the printer control unit, and delivering the image signal to the printer control unit  1009 . The printer control unit  1009  controls the developing units  405 ,  406 ,  407 , and  408 , the first fixing unit  413 , the second fixing unit  414 , and the like. The feeder control unit  1010  controls the external feeding apparatus  201 , the external feeding apparatus  202 , the feeding tray of the image forming apparatus main body  203 , and the inserter apparatus  204 . 
     The creaser control unit  1011  controls the creaser apparatus  205 . The sheet folding apparatus control unit  1012  controls the sheet folding apparatus  206 . The case binding control unit  1013  controls the case binding apparatus  207 . The finisher control unit  1014  controls the finisher apparatus  208 . The HDD I/F  1015  is an interface with the HDD  1016 , and controls write/readout to/from the HDD  1016 . The network I/F  1017  controls sending/reception of data via the network  104 . The HDD  1016  is a large-capacity storage device and is a nonvolatile area where data are saved. The network I/F  1017  is connected to the image processing apparatus  102  and the information processing apparatus  103  via the network  104 . 
     Control on each control unit by the CPU circuit unit  1001  at the time of a copy operation will be explained. Upon receiving a copy instruction from the operation panel control unit  1005 , the CPU circuit unit  1001  uses the document feeder control unit  1006 , and instructs the ADF  423  to feed documents of a document bundle one by one. The CPU circuit unit  1001  controls the scanner  424  via the image reader control unit  1007  to read the document and generate image data. 
     Then, the CPU circuit unit  1001  temporarily saves the generated image data in the RAM  1004 , and transfers it to the image signal control unit  1008 . The CPU circuit unit  1001  instructs the image signal control unit  1008  to convert the image data into an image signal interpretable by the printer control unit  1009 , and deliver the image signal to the printer control unit  1009 . At the same time, the CPU circuit unit  1001  uses the feeder control unit  1010  to issue an instruction to feed a printing medium from the external feeding apparatus  201  or  202  or the like. The printer control unit  1009  controls the developing units  405 ,  406 ,  407 , and  408 , the first fixing unit  413 , the second fixing unit  414 , and the like, and forms the read image on the fed medium. 
     The medium on which the image has been formed undergoes post-processes in accordance with an output form designated by the user. These post-processes are processes performed by the creaser control unit  1011 , the sheet folding apparatus control unit  1012 , the case binding control unit  1013 , and the finisher control unit  1014 . 
     For example, when performing crease processing on a medium, the CPU circuit unit  1001  uses the creaser control unit  1011  to execute crease processing on the medium. When folding a medium, the CPU circuit unit  1001  uses the sheet folding apparatus control unit  1012  to execute folding control. At this time, it is controlled to discharge the medium to the discharge portion  717  for a double parallel fold or C-fold, or convey the medium to the case binding apparatus  207  for a Z-fold, 6-page accordion fold, or single fold. When forming a case-bound product, the CPU circuit unit  1001  uses the case binding control unit  1013  to perform case-bound product formation processing and discharge media to the basket portion  819 . When performing formation processing by the finisher apparatus  208 , the CPU circuit unit  1001  uses the finisher control unit  1014  to perform processing corresponding to a designated discharge destination or a designated finishing setting such as saddle stitching or two-hole punching. The CPU circuit unit  1001  controls to discharge processed media to the sample tray  911 , the stacking tray  914 , or the saddle stacking portion  922 . 
     Next, control on each control unit by the CPU circuit unit  1001  at the time of a print operation will be explained. The CPU circuit unit  1001  receives print image data from the image processing apparatus  102  via the network I/F  1017 . The CPU circuit unit  1001  temporarily saves the received image data in the RAM  1004  and transfers it to the image signal control unit  1008 . Subsequent control is the same as that of the copy operation, and a description thereof will not be repeated. 
       FIG. 7B  is a block diagram showing in detail the creaser control unit  1011 . A CPU circuit unit  1101  includes a CPU  1102 , and controls the following control units in accordance with programs stored in a ROM  1103 . These control units are a die detection unit  1105 , a pressure control unit  1106 , and a conveyance path control unit  1107 . A RAM  1104  is used as an area for temporarily holding control data, and a work area for calculation accompanying control. 
     The CPU circuit unit  1101  is an intermediation circuit between the CPU circuit unit  1001 , and the die detection unit  1105 , pressure control unit  1106 , and conveyance path control unit  1107 . The CPU circuit unit  1101  has a function of intermediating an instruction from the CPU circuit unit  1001  and a notification from the control unit. The die detection unit  1105  is a detection unit that detects whether the creasing die  604  has been attached in the creaser apparatus  205 . 
     The pressure control unit  1106  controls the pressure devices  606  to  608 , and performs creasing by applying a pressure to the creasing die  604 . The conveyance path control unit  1107  controls the flapper  603 , the conveyance speed control unit  610 , and the like, and performs switching of the conveyance path for a medium and control of the conveyance speed. That is, the CPU circuit unit  1001  can perform centralized control of the die detection unit  1105 , pressure control unit  1106 , and conveyance path control unit  1107  via the CPU circuit unit  1101 , and can control crease processing and the conveyance path for the creaser apparatus  205 . 
       FIG. 7C  is a block diagram showing the hardware arrangements of the image processing apparatus  102  and information processing apparatus  103 . A CPU  1201  controls respective devices connected to a CPU device based on control programs stored in a ROM  1207 , an HDD  1209 , and a CDD (Compact Disk Drive)  1206 . 
     The display window of a display device  1202  displays, for example, windows, icons, messages, menus, and other kinds of operator interface information. In a VRAM (Video Random Access Memory)  1203 , a display image to be displayed on the display device  1202  is drawn. Display image data generated in the VRAM  1203  is transferred to the display device  1202  in accordance with a predetermined convention, and the display device  1202  displays the image. A keyboard  1204  includes various keys for inputting characters. A PD (Pointing Device)  1205  is used to designate, for example, icons, menus, and other objects displayed on the display screen of the display device  1202 . 
     The CDD  1206  is a device that reads out/writes various control programs and data from/to a recording medium such as a CD-ROM or a CD-R. The CDD  1206  may also be a DVD drive. The ROM  1207  holds various control programs and data. A RAM  1208  has a work area for the CPU  1201 , a data save area at the time of error processing, a control program loading area, and the like. 
     For example, the image processing apparatus  102  has a function of RIPing electronic data and sending the data to the image forming apparatus  101 . A program corresponding to this program is stored in the ROM  1207 . When performing RIP processing, the work area of the CPU  1201  or the RAM  1208  is used. The information processing apparatus  103  has a function of sending electronic data as a print job to the image processing apparatus  102 . A program corresponding to this function is stored in the ROM  1207 . When performing send processing, the work area of the CPU  1201  or the RAM  1208  is used. 
     The HDD  1209  is an internal recording device, and saves various control programs and various data. An external recording I/F  1210  is a device that performs readout/write from/to an external recording medium such as a USB memory. A network interface (Net-I/F)  1211  sends/receives data via a network  1212 . In this embodiment, data can be sent/received between the image forming apparatus  101 , the image processing apparatus  102 , and the information processing apparatus  103  via the network  104 . A CPU bus  1213  includes an address bus, a data bus, and a control bus. 
     [Software Arrangement] 
       FIG. 8  is a block diagram showing the software arrangements of the image forming apparatus  101 , image processing apparatus  102 , and information processing apparatus  103 . 
     A UI processing unit  1301 , a device control unit  1302 , a reception processing unit  1303 , a send processing unit  1304 , and a network I/F control unit  1305  are software modules that are executed by the CPU circuit unit  1001  of the image forming apparatus  101 . A UI processing unit  1306 , a job control unit  1307 , a RIP processing unit  1308 , a reception processing unit  1309 , a send processing unit  1310 , and a network I/F control unit  1311  are software modules that are executed by the CPU  1201  of the image processing apparatus  102 . A UI processing unit  1312 , a job generation unit  1313 , a send processing unit  1314 , and a network I/F control unit  1315  are software modules that are executed by the CPU  1201  of the information processing apparatus  103 . 
     The UI processing unit  1301  controls the operation panel control unit  1005 , and takes charge of display of a setting window and the like regarding the image forming apparatus  101  on the operation panel  425 . The UI processing unit  1301  takes charge of processing of saving/reading out values set on a setting window in/from the HDD  1016  of the image forming apparatus  101 . The device control unit  1302  controls the CPU circuit unit  1001 , and takes charge of processes such as image formation, creasing, folding, case-bound product formation, and saddle-stitched product formation by the image forming apparatus  101 . The device control unit  1302  also takes charge of processing of reading out settings about printing from the HDD  1016  of the image forming apparatus  101  and reflecting them in print processing. 
     The reception processing unit  1303  takes charge of processing of receiving, via the network I/F control unit  1305 , image data RIPed by the image processing apparatus  102 , and delivering the image data for each page to the device control unit  1302 . The send processing unit  1304  sends an event generated in the image forming apparatus  101 , a state change notification, and the like via the network I/F control unit  1305 . The network I/F control unit  1305  controls the network I/F  1017 . Further, the network I/F control unit  1305  takes charge of data communication processing between the image forming apparatus  101  and the image processing apparatus  102  via the network  104  in cooperation with the network I/F control unit  1311 . 
     The UI processing unit  1306  takes charge of processing of displaying a job state, settings, and the like on the display device  1202  of the image processing apparatus  102  when the image forming apparatus  101  and the image processing apparatus  102  execute a print job. The job control unit  1307  takes charge of print job send processing to the image forming apparatus  101 . More specifically, the job control unit  1307  performs processing such as sending of a print start request and job setting information for a print job. The RIP processing unit  1308  takes charge of processing of RIPing print data for each page. 
     The reception processing unit  1309  takes charge of processing of receiving an event, state change, and the like from the image forming apparatus  101  via the network I/F control unit  1311 , and delivering them to the UI processing unit  1306 . Further, the reception processing unit  1309  takes charge of processing of transferring, to the job control unit  1307 , a print job that has been received from the information processing apparatus  103  via the network I/F control unit  1311 . The send processing unit  1310  takes charge of processing of transferring RIPed image data for each page to the reception processing unit  1303  of the image forming apparatus  101  via the network I/F control unit  1311 . The network I/F control unit  1311  controls the Net-I/F  1211 . The network I/F control unit  1311  performs data communication processing between the image forming apparatus  101 , the image processing apparatus  102 , and the information processing apparatus  103  via the network  104 . 
     The UI processing unit  1312  takes charge of processing of displaying a job setting window on the display device  1202  of the information processing apparatus  103 , and processing of delivering, to the job generation unit  1313 , an instruction to generate a print job. The job generation unit  1313  takes charge of processing of generating a print job in accordance with an instruction from the UI processing unit  1312 , and delivering print data to the send processing unit  1314 . The send processing unit  1314  takes charge of delivering a print job to the reception processing unit  1309  of the image processing apparatus  102  via the network I/F control unit  1315 . The network I/F control unit  1315  controls the Net-I/F  1211 . Further, the network I/F control unit  1315  takes charge of data communication processing between the image processing apparatus  102  and the information processing apparatus  103  via the network  104  in cooperation with the network I/F control unit  1311 . 
     In this arrangement, a case in which the image processing apparatus  102  sends a print job from the information processing apparatus  103  and RIPs it, and then the image forming apparatus  101  prints is implemented by performing the following processing. First, the job generation unit  1313  of the information processing apparatus  103  generates a job in accordance with job settings made by the UI processing unit  1312 . The information processing apparatus  103  sends the generated print data and job setting information of the print job to the job control unit  1307  of the image processing apparatus  102  by using the send processing unit  1314 . The job control unit  1307  of the image processing apparatus  102  renders the received print data for each page by using the RIP processing unit  1308 , and sends the RIPed image data to the device control unit  1302  of the image forming apparatus  101  by using the send processing unit  1310 . The job control unit  1307  of the image processing apparatus  102  sends the job setting information to the device control unit  1302  of the image forming apparatus  101  by using the send processing unit  1310  in synchronism with the sending of the RIPed image data. 
     The device control unit  1302  of the image forming apparatus  101  receives the received RIPed image data, delivers the image data to the image signal control unit  1008 , and receives the job setting information. Based on the job setting information, the device control unit  1302  issues instructions about the feeding tray and discharge destination to the printer control unit  1009 , the feeder control unit  1010 , the finisher control unit  1014 , and the like. At this time, when controlling creasing or folding, the device control unit  1302  also issues instructions to the creaser control unit  1011  and the sheet folding apparatus control unit  1012 . In addition to issuing the instructions, the device control unit  1302  instructs the image signal control unit  1008  to deliver the image data to the printer control unit  1009 . 
     [Arrangement of Job Setting Window] 
       FIGS. 9A to 9D  show job setting windows displayed on the display device  1202  of the information processing apparatus  103 . This implements an acceptance unit that accepts job settings including a crease setting. In  FIG. 9A , a tag  1401  is a tag obtained by grouping job setting items by the type, and is constituted by six types “general”, “job information”, “medium”, “layout”, “finishing”, and “crease”. In  FIG. 9A , the setting item “medium” is displayed. The “medium” tag is a tag that collects settings associated with a medium used by a print job. 
     A medium type setting  1402 , a medium size setting  1403 , and a feeding tray setting  1404  are setting items about a medium used for a case binding cover or saddle stitching. In  FIG. 9A , “thick paper 1” is selected in the medium type setting  1402 , “A3” is selected in the medium size setting  1403 , and “auto select” is selected in the feeding tray setting  1404 . That is, it is set in  FIG. 9A  to print by feeding a medium from an arbitrary feeding tray as long as the medium type “thick paper 1” and the medium size “A3” are set for this feeding tray. 
     A medium type setting  1405 , a medium size setting  1406 , and a feeding tray setting  1407  are setting items about a medium used as a case binding inner sheet. In  FIG. 9A , “plain paper 1” is selected in the medium type setting  1405 , “A4” is selected in the medium size setting  1406 , and “auto select” is selected in the feeding tray setting  1407 . That is, it is set in  FIG. 9A  to print by feeding a medium from an arbitrary feeding tray as long as the medium type “plain paper 1” and the medium size “A4” are set for this feeding tray. 
     A medium type setting  1408 , a medium size setting  1409 , and a feeding tray setting  1410  are setting items about a medium used when neither case binding nor saddle stitching is performed. In  FIG. 9A , “plain paper 1” is selected in the medium type setting  1408 , “A3” is selected in the medium size setting  1409 , and “auto select” is selected in the feeding tray setting  1410 . That is, it is set in  FIG. 9A  to print by feeding a medium from an arbitrary feeding tray as long as the medium type “plain paper 1” and the medium size “A3” are set for this feeding tray. 
     A print button  1411  is a button for starting printing with contents set on the job setting window. An OK button  1412  is a button for deciding contents set on the job setting window as job settings. A cancel button  1413  is a button for discarding contents set on the job setting window. 
     In  FIG. 9B , the setting item “layout” is displayed. The “layout” tag is a tag that collects settings about a printing layout. A printing method setting  1414  and a binding direction setting  1415  are setting items about the layout of a case binding cover or saddle stitching. In  FIG. 9B , “double sided” is selected in the printing method setting  1414 , and “short-edge binding” is selected in the binding direction setting  1415 . That is, it is set in  FIG. 9B  as the layout of the case binding cover or saddle stitching to perform double-sided printing for image data of two pages by short-edge binding. 
     A printing method setting  1416  and a binding direction setting  1417  are setting items about the layout of a case binding inner sheet. In  FIG. 9B , “double sided” is selected in the printing method setting  1416 , and “long-edge binding” is selected in the binding direction setting  1417 . That is, it is set in  FIG. 9B  as the layout of a case binding inner sheet to perform double-sided printing for image data of two pages by long-edge binding. A printing method setting  1418  and a binding direction setting  1419  are setting items about a layout when neither case binding nor saddle stitching is performed. In  FIG. 9B , “single sided” is selected in the printing method setting  1418 , and “none” is selected in the binding direction setting  1419 . That is, it is set in  FIG. 9B  as a layout when neither case binding nor saddle stitching is performed, to perform single-sided printing for image data of one page. The print button  1411 , the OK button  1412 , and the cancel button  1413  are the same as those in  FIG. 9A , and a description thereof will not be repeated. 
     In  FIG. 9C , the setting item “finishing” is displayed. The “finishing” tag is a tag that collects settings about discharge and formation. A discharge destination setting  1420  is a setting about designation of a discharge destination, and “case binding apparatus” is selected in  FIG. 9C . In this setting, the sample tray  911 , stacking tray  914 , and saddle stacking portion  922  of the finisher apparatus  208 , and the like are selectable in addition to the case binding apparatus. 
     A punch setting  1421  is an item for setting whether to perform punch processing on a medium when discharging the medium to the finisher apparatus  208 . In  FIG. 9C , “OFF” is designated in the punch setting  1421 . A staple setting  1422  is an item for setting whether to perform staple processing on a medium when discharging the medium to the finisher apparatus  208 . In  FIG. 9C , “OFF” is designated in the staple setting  1422 . A fold setting  1423  is an item for setting whether to perform fold processing by the sheet folding apparatus  206 . In  FIG. 9C , “OFF” is designated in the fold setting  1423 . In this setting, “Z-fold”, “6-page accordion fold”, “single fold”, “double parallel fold”, and “C-fold” as described with reference to  FIG. 5B  are selectable in addition to “OFF”. 
     A saddle stitching setting  1424  is an item for setting whether to perform saddle stitch processing on a medium when discharging the medium to the finisher apparatus  208 . In  FIG. 9C , “OFF” is set in the saddle stitching setting  1424 . A case binding setting  1425  is an item set when forming a case-bound product by the case binding apparatus  207 . In  FIG. 9C , “ON” is set in the case binding setting  1425 . The print button  1411 , the OK button  1412 , and the cancel button  1413  are the same as those in  FIG. 9A , and a description thereof will not be repeated. 
     In  FIG. 9D , the setting item “crease” is displayed. The “crease” tag is a tag that collects settings about crease processing. A crease setting  1426  for a hinge at the time of bookbinding is a setting about whether to make a crease at a hinge position at the time of case binding and saddle stitching. In  FIG. 9D , “ON” is selected. This setting is a radio button setting, and “ON” or “OFF” is alternatively selected. 
     An offset position  1427  from a spine edge at the time of bookbinding is a setting about a position where a crease for a hinge is made when the crease setting  1426  for a hinge at the time of bookbinding is “ON”. In  FIG. 9D , it is set to make a crease for a hinge at a position of “15.0 mm” from a spine edge. A crease setting  1428  for each page is an item representing the position and purpose of a crease for each page. In  FIG. 9D , nothing is set in the crease setting for each page (no setting). The print button  1411 , the OK button  1412 , and the cancel button  1413  are the same as those in  FIG. 9A , and a description thereof will not be repeated. 
     Note that the settings on the respective windows shown in  FIGS. 9A to 9D  are read out from or written in the HDD  1209  by the UI processing unit  1312  using the CPU  1201 . When executing printing, the UI processing unit  1312  performs processing of requesting the job generation unit  1313  to generate a job. 
     [Description of Hinge] 
       FIGS. 10A to 10C  give a description of a hinge for a case binding cover. The “spine edge”, “hinge”, and “offset” in this embodiment will be clearly defined with reference to  FIGS. 10A to 10C . Further, the relationship between “spine edge”, “hinge”, “offset”, “crease position 1”, “crease position 2”, “crease position 3”, and “crease position 4” will be explained. 
       FIGS. 10A and 10B  show the positional relationship between the spine edge and the hinge in regard to case binding. As shown in  FIG. 10A , one hinge exists for each of front and back covers in case binding. The interval between the spine edge and the hinge is defined by a name “offset”, and the interval between two spine edges is defined by a name “thickness of the spine cover”. Note that the offset in  FIG. 10B  corresponds to the “offset position from a spine edge at the time of bookbinding”  1427  shown in  FIG. 9D . In the example of  FIG. 9D , the length of the offset in  FIG. 10B  is set to be “15.0 mm”. 
       FIG. 10C  shows the positions of the spine edge and hinge from a reference position (leading end of a medium) for a case binding cover. As described above with reference to  FIG. 6A , an inner sheet bundle is glued to the center of a case binding cover. Therefore, lengths from the reference position (leading end of a medium) to “crease position 1”, “crease position 2”, “crease position 3”, and “crease position 4” have a relationship shown in  FIG. 10C  with the length of a medium serving as a case binding cover, the thickness of the spine cover, and the offset. Note that the thickness of the spine cover depends on the type and number of media used as case binding inner sheets, and changes for each case-bound product to be generated. 
     The relationship in  FIG. 10C  is represented by the following equations:
 
crease position 1(hinge)=(length of case binding cover/2)−(thickness of spine cover/2)−offset value
 
crease position 2(spine edge)=(length of case binding cover/2)−(thickness of spine cover/2)
 
crease position 3(spine edge)=(length of case binding cover/2)+(thickness of spine cover/2)
 
crease position 4(hinge)=(length of case binding cover/2)+(thickness of spine cover/2)+offset value
 
       FIG. 11  shows an example of the arrangement of a management table for a pressure when making a crease (to be referred to as a “creasing pressure” hereinafter). A management table  1600  is saved in the HDD  1016  of the image forming apparatus  101 . In  FIG. 11 , a medium ID  1601  is an identifier (identification information) for uniquely identifying a medium. A medium type  1602  is the name of a medium for each medium ID. The value of the medium type  1602  is displayed in the medium type settings  1402 ,  1405 , and  1408  in  FIG. 9A . A creasing pressure  1603  for a hinge is a pressure when the creasing purpose is “hinge”. A creasing pressure  1604  for a spine edge is a pressure when the creasing purpose is “spine edge”. 
     In the example of  FIG. 11 , creasing pressures appropriate for respective creasing purposes are managed in association with three respective types of media. Note that a creasing pressure managed in the management table  1600  is a creasing pressure used when the creaser apparatus  205  performs crease processing on a medium. Medium types are not limited to those shown in  FIG. 11 , and another type of medium may be registered and handled. A creasing pressure may be further defined for another creasing purpose. The creasing pressures associated with respective media shown in  FIG. 11  are merely an example and, for example, another creasing pressure obtained empirically or experimentally may be used. 
     First Embodiment 
     The first embodiment will explain a case in which when an information processing apparatus  103  sends a case binding job to an image processing apparatus  102 , a “crease for a hinge” and a “crease for a spine edge (crease for a fold)” are made on a case binding cover. 
     The premise of the first embodiment will be explained. First, assume that the above-described settings shown in  FIGS. 9A to 9D  are made as settings of the case binding job sent from the information processing apparatus  103 . 
     When the operator presses a print button  1411  in the information processing apparatus  103 , a UI processing unit  1312  of the information processing apparatus  103  requests a job generation unit  1313  to generate a job, and the job generation unit  1313  generates a case binding job. Assume that the job generation unit  1313  has sent the generated job to a job control unit  1307  of the image processing apparatus  102  by using a send processing unit  1314 . 
     [Processing Sequence] 
     The first embodiment will be explained with reference to the flowcharts of  FIGS. 12 and 13 .  FIG. 12  is a flowchart showing processing to be executed by the job control unit  1307  of the image processing apparatus  102 . A program regarding this processing is stored in a ROM  1207  of the image processing apparatus  102 , and read out and executed by a CPU  1201 .  FIG. 13  is a flowchart showing processing to be executed by a device control unit  1302  of an image forming apparatus  101 . A program regarding this processing is stored in a ROM  1003  of the image forming apparatus  101 , and read out and executed by a CPU  1002 . 
     (Processing in Image Processing Apparatus) 
     First, processing in  FIG. 12  will be explained. When the process starts, the job control unit  1307  determines in step S 1701  whether it has received a print job from the job generation unit  1313 . If the job control unit  1307  has received a print job (YES in step S 1701 ), it advances to step S 1702 . If the job control unit  1307  has not received a print job (NO in step S 1701 ), it waits until it receives a print job. 
     In step S 1702 , the job control unit  1307  analyzes job setting information of the received print job, and determines whether the print job is a case binding job. More specifically, when a discharge destination setting  1420  is “case binding apparatus” and a case binding setting  1425  is “ON”, it is determined that the print job is a case binding job. If the received print job is a case binding job (YES in step S 1702 ), the job control unit  1307  advances to step S 1706 . If the received print job is not a case binding job (NO in step S 1702 ), the job control unit  1307  advances to step S 1703 . 
     In step S 1703 , the job control unit  1307  generates configuration information based on items set in “medium” and “layout” of the job setting window. At this time, the job control unit  1307  inquires, of the device control unit  1302  of the image forming apparatus  101 , the medium ID of a medium type set in a medium type setting  1402  or  1408 , and sets the obtained medium ID in the configuration information. Also, the job control unit  1307  generates finishing information based on items set in “finishing” and “crease” of the job setting window. 
     In step S 1704 , the job control unit  1307  sends a print start request to the device control unit  1302  of the image forming apparatus  101 . Together with this request, the job control unit  1307  sends the configuration information and finishing information generated in step S 1703 . In step S 1705 , the job control unit  1307  instructs an RIP processing unit  1308  to send RIPed image data of the print job to the device control unit  1302  of the image forming apparatus  101 . Then, the job control unit  1307  ends this processing sequence. 
     In step S 1706 , the job control unit  1307  analyzes the job setting information of the received print job, and obtains the medium types of a case binding cover and case binding inner sheet. In the example of  FIG. 9A , these medium types correspond to the medium type setting  1402  and a medium type setting  1405 . 
     In step S 1707 , the job control unit  1307  analyzes the job setting information of the received print job, and calculates the number of inner sheets. More specifically, the number of inner sheets is calculated based on the number of logical pages included in the print job, and the setting of a printing method setting  1416 . In the example of  FIG. 9B , the printing method setting  1416  is “double sided”. Thus, the number of logical pages is divided by 2, and the result of adding a remainder to the quotient serves as the number of inner sheets. When the printing method setting  1416  is “single sided”, the number of logical pages directly indicates the number of inner sheets. 
     In step S 1708 , the job control unit  1307  calculates the thickness of the spine cover according to:
 
thickness of spine cover=(thickness of medium serving as case binding cover)+(thickness of medium serving as case binding inner sheet×number of inner sheets)
 
     The thickness of each medium to be used here is saved in advance in an HDD  1016  of the image forming apparatus  101 , and is managed in association with the medium ID. The thickness of each medium is obtained by inquiring it of the device control unit  1302  of the image forming apparatus  101  by the job control unit  1307 . Note that the spine cover thickness calculation equation is not limited to this embodiment and may be an equation considering a mixture of media serving as inner sheets. An external factor such as gluing may also be taken into account. 
     In step S 1709 , the job control unit  1307  analyzes the job setting information of the received print job, obtains a crease setting  1426  for a hinge at the time of bookbinding, and confirms the setting content. If the crease setting  1426  for a hinge at the time of bookbinding is ON (YES in step S 1709 ), the job control unit  1307  advances to step S 1711 . If the crease setting  1426  for a hinge at the time of bookbinding is OFF (NO in step S 1709 ), the job control unit  1307  advances to step S 1710 . 
     In step S 1710 , the job control unit  1307  calculates crease position 2 and crease position 3. The job control unit  1307  analyzes the job setting information of the received print job, and obtains a medium size from a medium size setting  1403 . In the example of  FIG. 9A , “A3” is designated in the medium size setting  1403 . “A3” is a standard size, and its size in the conveyance direction is 420.0 mm. The job control unit  1307  calculates crease position 2 and crease position 3 based on the medium size setting  1403  and the thickness of the spine cover calculated in step S 1708 . After that, the job control unit  1307  advances to step S 1713 . Here, assume that information about the length (size) of a standard-size medium is held in the image processing apparatus  102 , and the information about the length of a standard size is saved in advance in an HDD  1209 . 
     In step S 1711 , the job control unit  1307  analyzes the job setting information of the received print job, and obtains an offset position  1427  from a spine edge at the time of bookbinding. In step S 1712 , the job control unit  1307  calculates crease position 1, crease position 2, crease position 3, and crease position 4. The job control unit  1307  analyzes the job setting information of the received print job, and obtains a medium size from the medium size setting  1403 . In the example of  FIG. 9A , “A3” is designated in the medium size setting  1403 . “A3” is a standard size, and its size in the conveyance direction is 420.0 mm. The job control unit  1307  calculates the four crease positions based on the medium size setting  1403 , the thickness of the spine cover calculated in step S 1708 , and the offset position  1427  from a spine edge at the time of bookbinding that has been obtained in step S 1711 . 
     In step S 1713 , the job control unit  1307  associates the crease position calculated in step S 1710  or S 1712  with a creasing purpose. More specifically, after passing through the processing in step S 1710 , the job control unit  1307  decides that two creases at crease position 2 and crease position 3 have the purpose “crease for a spine edge (crease for a fold)” on a case binding cover, and associates them. In this case, a “crease for a hinge” does not exist. After passing through the processing in step S 1712 , the job control unit  1307  decides that two creases at crease position 1 and crease position 4 have the purpose “crease for a hinge” on a case binding cover, and associates them. Further, the job control unit  1307  decides that two creases at crease position 2 and crease position 3 have the purpose “crease for a spine edge (crease for a fold)”, and associates them. 
     In step S 1714 , the job control unit  1307  generates configuration information based on items set in “medium” and “layout” of the job setting window. At this time, the job control unit  1307  inquires, of the device control unit  1302  of the image forming apparatus  101 , the medium ID of a medium type set in the medium type setting  1402  or  1408 , and sets the obtained medium ID in the configuration information. Also, the job control unit  1307  generates finishing information based on items set in “finishing” and “crease” of the job setting window. At this time, the job control unit  1307  sets, in the finishing information, even the association information of the crease position and creasing purpose that has been generated in step S 1713 . 
     In step S 1715 , the job control unit  1307  sends a print start request to the device control unit  1302  of the image forming apparatus  101 . Together with this request, the job control unit  1307  sends the configuration information and finishing information generated in step S 1714 . In step S 1716 , the job control unit  1307  instructs the RIP processing unit  1308  to send RIPed image data of the case binding job to the device control unit  1302  of the image forming apparatus  101 . Then, the job control unit  1307  ends this processing sequence. 
     (Processing in Image Forming Apparatus) 
     Next, processing in  FIG. 13  will be explained. When the process starts, the device control unit  1302  of the image forming apparatus  101  determines in step S 1801  whether it has received a print start request for a print job from the job control unit  1307 . If the device control unit  1302  has received a print start request (YES in step S 1801 ), it advances to step S 1802 . If the device control unit  1302  has not received a print start request (NO in step S 1801 ), it waits until it receives a print start request. 
     In step S 1802 , the device control unit  1302  analyzes finishing information of the received print job, and determines whether the print job is a case binding job. More specifically, when the discharge destination setting  1420  described with reference to  FIG. 9C  is “case binding apparatus” and the case binding setting  1425  is “ON”, it is determined that the print job is a case binding job. If the print request is case binding (YES in step S 1802 ), the device control unit  1302  advances to step S 1804 . If the print request is not case binding (NO in step S 1802 ), the device control unit  1302  advances to step S 1803 . 
     In step S 1803 , the device control unit  1302  performs print processing by the image forming apparatus  101  based on the configuration information and finishing information of the received print job. Then, the device control unit  1302  ends this processing sequence. 
     In step S 1804 , the device control unit  1302  analyzes the configuration information of the received print request, and obtains the medium ID of a case binding cover. In step S 1805 , the device control unit  1302  analyzes the finishing information of the received print job, and obtains the number of times of creasing, crease positions, and creasing purposes for the respective crease positions. More specifically, when the image processing apparatus  102  has passed through the processing in step S 1710  of  FIG. 12 , “2” is obtained as the number of times of creasing, crease position 2 and crease position 3 are obtained as crease positions, and the “crease for a spine edge (crease for a fold)” is obtained as a creasing purpose for each crease position. When the image processing apparatus  102  has passed through the processing in step S 1712  of  FIG. 12 , “4” is obtained as the number of times of creasing, and crease position 1, crease position 2, crease position 3, and crease position 4 are obtained as crease positions. As the creasing purpose, the “crease for a hinge” is obtained for crease position 1 and crease position 4, and the “crease for a spine edge (crease for a fold)” is obtained for crease position 2 and crease position 3. 
     In step S 1806 , the device control unit  1302  obtains, from a creasing pressure management table  1600  saved in the HDD  1016 , a “creasing pressure for a hinge” and a “creasing pressure for a spine edge” for all medium IDs obtained in step S 1804 . Since “thick paper 1” is designated in the medium type setting  1402  in this embodiment, “140 Kgf” is obtained as the creasing pressure for a hinge, and “100 Kgf” is obtained as the creasing pressure for a spine edge. 
     In step S 1807 , the device control unit  1302  instructs a CPU circuit unit  1101  of a creaser apparatus  205  via a CPU circuit unit  1001  of the image forming apparatus  101  about crease processing on a case binding cover. At this time, the device control unit  1302  issues an instruction to perform creasing based on the settings obtained in steps S 1805  and S 1806 . More specifically, an instruction is issued to perform creasing at “140 Kgf” as the creasing pressure for a hinge at a position where it is set to make a crease for a hinge. When it is set to make a crease for a spine edge (crease for a fold), an instruction is issued to perform creasing at “100 Kgf” as the pressure of a crease for a spine edge (crease for a fold). As described above with reference to  FIG. 4 , the creasing pressure can be controlled to an arbitrary pressure by controlling pressure devices  606  to  608 . 
     In step S 1808 , the device control unit  1302  controls the CPU circuit unit  1001  of the image forming apparatus  101  to execute printing on a medium used for case binding, and execute crease processing on a case binding cover. In step S 1809 , the device control unit  1302  instructs a case binding control unit  1013  via the CPU circuit unit  1001  of the image forming apparatus  101  to form a case-bound product. After that, the device control unit  1302  ends this processing sequence. By this processing, the case-bound product is formed using media printed and creased in step S 1808 . 
     As described above, a crease can be made on a case binding cover at a plurality of creasing pressures in accordance with creasing purposes. 
     Second Embodiment 
     The second embodiment will explain a case in which when an information processing apparatus  103  sends a print job to an image processing apparatus  102 , a “crease for a hinge” and a “crease for a spine edge (crease for a fold)” are made on an arbitrary medium. This embodiment will give an explanation by exemplifying a case in which printing and creasing on a medium used in case binding are performed when executing offline case binding. 
       FIG. 14  shows a setting window according to the second embodiment that corresponds to the setting window shown in  FIG. 9D  in the first embodiment. A crease setting  1901  for a hinge at the time of bookbinding is a setting about whether to make a crease at a hinge position at the time of case binding and saddle stitching. In  FIG. 14 , “OFF” is selected. This setting is a radio button setting, and “ON” or “OFF” is alternatively selected. 
     A crease setting  1903  for each page is an item representing the position and purpose of a crease for each page. In  FIG. 14 , it is set to make four creases for the first page. It is also set to make “creases for hinges” at positions of 200 mm and 240 mm from the leading end of a sheet, and “creases for spine edges (creases for folds)” at positions of 210 mm and 230 mm. An offset position  1902  from a spine edge at the time of bookbinding, a print button  1904 , an OK button  1905 , and a cancel button  1906  are the same as those in  FIG. 9A , and a description thereof will not be repeated. 
     The second embodiment assumes that a stacking tray  914  of a finisher apparatus  208  is set in a discharge destination setting  1420  shown in  FIG. 9C . Further, the second embodiment assumes that data to be printed for the first page is print data of a case binding cover and the remaining data are print data of case binding inner sheets. 
     [Processing Sequence] 
     The second embodiment will be explained with reference to the flowcharts of  FIGS. 15 and 16 .  FIGS. 15A and 15B  are flowcharts showing processing to be executed by a job control unit  1307  of the image processing apparatus  102 . A program regarding this processing is stored in a ROM  1207  of the image processing apparatus  102 , and read out and executed by a CPU  1201 .  FIG. 16  is a flowchart showing processing to be executed by a device control unit  1302  of an image forming apparatus  101 . A program regarding this processing is stored in a ROM  1003  of the image forming apparatus  101 , and read out and executed by a CPU  1002 . 
     First, as in the first embodiment, when the operator presses the print button  1904  in the information processing apparatus  103 , a UI processing unit  1312  requests a job generation unit  1313  to generate a job. In response to this request, the job generation unit  1313  generates a print job. Assume that the job generation unit  1313  has sent the generated job to the job control unit  1307  of the image processing apparatus  102  via a send processing unit  1314 . 
     (Processing in Image Processing Apparatus) 
     Subsequently, processing by the job control unit  1307  of the image processing apparatus  102  will be explained with reference to  FIGS. 15A and 15B . When the process starts, the job control unit  1307  determines in step S 2001  whether it has received a print job from the job generation unit  1313  of the information processing apparatus  103 . If the job control unit  1307  has received a print job (YES in step S 2001 ), it advances to step S 2002 . If the job control unit  1307  has not received a print job (NO in step S 2001 ), it waits until it receives a print job. 
     In step S 2002 , the job control unit  1307  analyzes job setting information of the received print job, and determines whether a crease setting for each page has been made. More specifically, the job control unit  1307  makes this determination based on whether a setting is made in the crease setting  1903  for each page shown in  FIG. 14 . If a crease setting for each page has been made (YES in step S 2002 ), the job control unit  1307  advances to step S 2006 . If a crease setting for each page has not been made (NO in step S 2002 ), the job control unit  1307  advances to step S 2003 . Steps S 2003  to S 2005  are the same as those in steps S 1703  to S 1705  in  FIG. 17 , and a description thereof will not be repeated. 
     In step S 2006 , the job control unit  1307  analyzes the job setting information of the received print job, and determines single- or double-sided printing. More specifically, the job control unit  1307  makes this determination based on settings in a discharge destination setting  1420  shown in  FIG. 9C , and printing method settings  1414 ,  1416 , and  1418  shown in  FIG. 9B . If the job setting information represents single-sided printing (YES in step S 2006 ), the job control unit  1307  advances to step S 2007 . If the job setting information represents double-sided printing (NO in step S 2006 ), the job control unit  1307  advances to step S 2008 . Since a stacking tray  914  is set in the discharge destination setting  1420 , the setting in the printing method setting  1418  is referred to, and it is assumed to determine that the job setting information represents single-sided printing. 
     In step S 2007 , the job control unit  1307  refers to a medium type setting  1408  shown in  FIG. 9A  and the crease setting  1903  for each page shown in  FIG. 14 . First, the job control unit  1307  inquires, of the device control unit  1302  of the image forming apparatus  101 , the medium ID of a medium type set in the medium type setting  1408 . In the second embodiment, “plain paper 1” is set in the medium type setting  1408 , so a medium ID “3” is obtained based on a management table  1600  shown in  FIG. 11 . Further, the job control unit  1307  reads out settings for one page from settings in the crease setting  1903  for each page, and extracts the number of times of creasing, crease positions, and creasing purposes. After that, the job control unit  1307  advances to step S 2011 . 
     In step S 2008 , the job control unit  1307  refers to the medium type setting  1408  shown in  FIG. 9A  and the crease setting  1903  for each page shown in  FIG. 14 . First, the job control unit  1307  inquires, of the device control unit  1302 , the medium ID of a medium type set in the medium type setting  1408 . Then, the job control unit  1307  reads out settings for two pages from settings in the crease setting  1903  for each page, and extracts the number of times of creasing, crease positions, and creasing purposes. After that, the job control unit  1307  advances to step S 2009 . 
     In step S 2009 , the job control unit  1307  determines whether the crease setting is made for the two surfaces. If the crease setting is made for the two surfaces (YES in step S 2009 ), the process advances to step S 2010 . If the crease setting is not made for the two surfaces (NO in step S 2009 ), the process advances to step S 2011 . 
     In step S 2010 , the job control unit  1307  discards the crease setting made for the back surface, and leaves only the setting of the front surface. The job control unit  1307  then advances to step S 2010 . 
     The second embodiment assumes processing of discarding the crease setting of one surface (back surface in this case) to simplify the description. Instead of this processing, the crease settings of the front and back surfaces may be integrated into a crease on one surface. In this case, it is necessary to consider that the references of crease positions on the front and back surfaces are set for each logical page. For example, when the crease position of the back surface is integrated into the crease position of the front surface, it is controlled to set, as a crease position, a length obtained by subtracting the crease position of the back surface from the length of a medium in the conveyance direction in consideration of the medium size setting  1409  and the binding direction setting  1419 . Depending on the medium type, even if creases are set for the two surfaces, they may be made without any change. Hence, when creases are set for the two surfaces, it may be determined whether to remove or integrate creases depending on the medium type. 
     In step S 2011 , the job control unit  1307  holds, in a RAM  1004 , the number of times of creasing, crease positions, creasing purposes, and a medium ID for the nth medium to be printed. In step S 2012 , the job control unit  1307  checks whether the processes in steps S 2006  to S 2011  have been completed on all the pages of the print data. If the processes have been completed on all the pages (YES in step S 2012 ), the job control unit  1307  advances to step S 2013 . If the processes have not been completed on all the pages (NO in step S 2012 ), the job control unit  1307  returns to step S 2006  and repeats the processing on an unprocessed page. 
     In step S 2013 , the job control unit  1307  generates configuration information based on items set in “medium” and “layout” of the job setting window. At this time, the job control unit  1307  inquires, of the device control unit  1302  of the image forming apparatus  101 , the medium ID of a medium type set in the medium type setting  1402  or  1408 , and sets the obtained medium ID in the configuration information. Also, the job control unit  1307  generates finishing information based on items set in “finishing” and “crease” of the job setting window. At this time, the job control unit  1307  sets, in the finishing information, even association information of the crease position and creasing purpose that has been generated in step S 2011 . 
     In step S 2014 , the job control unit  1307  sends a print start request to the device control unit  1302  of the image forming apparatus  101 . Together with this request, the job control unit  1307  sends the configuration information and finishing information generated in step S 2013 . In step S 2015 , the job control unit  1307  instructs a RIP processing unit  1308  to send RIPed image data of the print job to the device control unit  1302  of the image forming apparatus  101 . Then, the job control unit  1307  ends this processing sequence. 
     (Processing in Image Forming Apparatus) 
     Next, processing in  FIG. 16  will be explained. When the process starts, the device control unit  1302  determines in step S 2101  whether it has received a print start request from the job control unit  1307  of the image processing apparatus  102 . If the device control unit  1302  has received a print start request for a print job (YES in step S 2101 ), it advances to step S 2102 . If the device control unit  1302  has not received a print start request (NO in step S 2101 ), it waits until it receives a print start request. 
     In step S 2102 , the device control unit  1302  analyzes finishing information of the received print job, and determines whether crease processing has been set. If crease processing has been set (YES in step S 2102 ), the device control unit  1302  advances to step S 2104 . If no crease processing has been set (NO in step S 2102 ), the device control unit  1302  advances to step S 2103 . 
     In step S 2103 , the device control unit  1302  performs print processing by the image forming apparatus  101  based on the received configuration information and finishing information. Upon completion of print processing, the device control unit  1302  ends this processing sequence. 
     In step S 2104 , the device control unit  1302  analyzes the finishing information of the received print request, and obtains the number of times of creasing, crease positions, creasing purposes, and a medium ID for each medium. In this case, a setting of making, on the first medium, “creases for hinges” at positions of 200 mm and 240 mm from the leading end of a sheet, and “creases for spine edges (creases for folds)” at positions of 210 mm and 230 mm is obtained. In addition, a medium ID “3” is obtained. 
     In step S 2105 , the device control unit  1302  obtains, from the creasing pressure management table  1600  shown in  FIG. 11  that is saved in an HDD  1016 , a “creasing pressure for a hinge” and a “creasing pressure for a spine edge” for all medium IDs obtained in step S 2104 . Since the medium ID is “3” in this case, “120 Kgf” is obtained as the creasing pressure for a hinge, and “80 Kgf” is obtained as the creasing pressure for a spine edge. 
     In step S 2106 , the device control unit  1302  instructs a CPU circuit unit  1101  of a creaser apparatus  205  via a CPU circuit unit  1001  of the image forming apparatus  101  about crease processing on the medium. At this time, the device control unit  1302  issues an instruction to perform creasing based on the settings obtained in step S 2104 . In this case, the device control unit  1302  issues an instruction to make creases at positions of 200 mm and 240 mm from the leading end of a sheet at a pressure of 120 Kfg and creases at positions of 210 mm and 230 mm at a pressure of 80 Kfg. 
     In step S 2107 , the device control unit  1302  uses the CPU circuit unit  1001  of the image forming apparatus  101  to execute printing and execute crease processing on the first medium. Further, the device control unit  1302  executes discharge to the stacking tray  914  of the finisher apparatus  208 . The device control unit  1302  then ends this processing sequence. 
     As described above, creases can be made on one medium at a plurality of creasing pressures in accordance with creasing purposes. In this embodiment, creases can be made on an arbitrary medium constituting a case-bound product at an arbitrary page desired by the operator at a plurality of creasing pressures in accordance with creasing purposes based on crease settings for each page. 
     This embodiment has described an example in which no crease for a hinge is applied to a cover at the time of bookbinding. When a crease for a hinge is applied, the same processing as that in the first embodiment may be executed additionally. 
     Third Embodiment 
     The third embodiment will exemplify a case in which a creaser apparatus  205  of an image forming apparatus  101  includes only one pressure device. The third embodiment will describe an example in which the creasing pressure is controlled by changing a creasing die  604 . In the third embodiment, there are a plurality of types of creasing dies. Each creasing die is associated with an ID (identification information), and the creaser apparatus  205  can read the ID of the creasing die. The creasing die controls a creasing pressure with respect to a medium by a spring incorporated in the die. In this embodiment, a die for the “creasing pressure of 100 Kgf” is associated with a die ID “1”, and a die for the “creasing pressure of 140 Kgf” is associated with a die ID “2”. 
     Since the premise of the third embodiment is the same as that of the first embodiment, a description of a repetitive part will be omitted, and settings and processing unique to the third embodiment will be explained with reference to  FIGS. 17 to 19 . 
       FIG. 17  is a sectional view showing the creaser apparatus  205  according to the third embodiment. Compared with  FIG. 4 , the three pressure devices  606  to  608  exist in the first embodiment, whereas only a pressure device  2206  exists in the third embodiment. The remaining arrangement is the same as that in  FIG. 4 , and a description thereof will not be repeated. 
       FIGS. 18A and 18B  show message windows displayed on an operation panel  425  of the image forming apparatus  101 .  FIG. 18A  shows a message displayed when a creasing die corresponding to a creasing purpose has not been attached in the creaser apparatus  205 . As an example of a message  2301 , a message that a creasing die (ID=1) for a spine edge has not been attached is displayed. An OK button  2302  is a button that is pressed by the operator after confirming the message  2301 . When the operator presses the OK button  2302 , the message in  FIG. 18A  disappears. 
       FIG. 18B  shows a message displayed to prompt the operator to feed a medium to an inserter apparatus  204  and change a die attached in the creaser apparatus  205 . As an example of a message  2303 , a message to change the die with a creasing die (ID=2) for a hinge is displayed. An OK button  2304  is a button that is pressed by the operator after confirming the message  2303 . When the operator presses the OK button  2304 , the message in  FIG. 18B  disappears. Note that a UI processing unit  1301  of the image forming apparatus  101  controls display/non-display of the windows shown in  FIGS. 18A and 18B . 
     [Processing Sequence] 
       FIG. 19  is a flowchart showing processing to be executed by a device control unit  1302  of the image forming apparatus  101 . A program regarding this processing is stored in a ROM  1003  of the image forming apparatus  101 , and read out and executed by a CPU  1002 . Processes by an information processing apparatus  103  and an image processing apparatus  102  are the same as those in the first embodiment, and a description thereof will not be repeated. Steps S 2401  to S 2406  are the same as steps S 1801  to S 1806  of  FIG. 13  described in the first embodiment, and a description thereof will not be repeated. 
     In step S 2407 , the device control unit  1302  instructs a CPU circuit unit  1101  of the creaser apparatus  205  via a CPU circuit unit  1001  of the image forming apparatus  101  to obtain the ID of an attached creasing die. Upon receiving the instruction, the CPU circuit unit  1101  obtains the ID of the attached creasing die from a die detection unit  1105 , and sends it back to the device control unit  1302  via the CPU circuit unit  1001 . 
     In step S 2408 , the device control unit  1302  checks whether a creasing die for a spine edge has been attached. More specifically, when the medium ID is “1”, the creasing pressure for a spine edge is “100 Kgf”. Hence, if the ID of the creasing die is “1” (YES in step S 2408 ), the device control unit  1302  advances to step S 2411  on the assumption that an appropriate creasing die has been attached. If the ID of the creasing die is not “1” (NO in step S 2408 ), the device control unit  1302  advances to step S 2409 . 
     In step S 2409 , the device control unit  1302  instructs the UI processing unit  1301  to display the message in  FIG. 18A . In step S 2410 , the device control unit  1302  waits until the operator attaches a die for a “crease for a spine edge (crease for a fold)” in the creaser apparatus  205 . More specifically, the device control unit  1302  waits until the ID of the creasing die changes to “1”. If the ID of the creasing die has changed to “1” (YES in step S 2410 ), the device control unit  1302  determines that the creasing die has been changed with a target one, and advances to step S 2411 . If the ID of the creasing die has not changed to “1” (NO in step S 2410 ), the device control unit  1302  waits until the creasing die is changed. 
     In step S 2411 , the device control unit  1302  executes printing on a case binding cover, further makes a “crease for a spine edge (crease for a fold)”, and then discharges the medium to a sample tray  911  of a finisher apparatus  208 . In step S 2412 , the device control unit  1302  instructs the UI processing unit  1301  to display the message in  FIG. 18B . 
     In step S 2413 , the device control unit  1302  checks whether the medium has been fed to an inserter tray  503  of the inserter apparatus  204 . More specifically, the device control unit  1302  obtains a state detected by a sheet detection sensor  504  from a feeder control unit  1010  via the CPU circuit unit  1001  of the image forming apparatus  101 , and checks whether the medium has been fed. If the medium has been fed (YES in step S 2413 ), the device control unit  1302  advances to step S 2414 . If the medium has not been fed (NO in step S 2413 ), the device control unit  1302  waits until the medium is fed. 
     In step S 2414 , the device control unit  1302  waits until the operator attaches a die for a “crease for a hinge” in the creaser apparatus  205 . More specifically, a target creasing pressure for a hinge when the medium ID is “1” is “140 Kgf”. Thus, the device control unit  1302  waits until the ID of the creasing die changes to “2”. If the ID of the creasing die has changed to “2” (YES in step S 2414 ), the device control unit  1302  determines that the creasing die has been changed with a target one, and advances to step S 2415 . If the ID of the creasing die has not changed to “2” (NO in step S 2414 ), the device control unit  1302  waits until the creasing die is changed. 
     In step S 2415 , the device control unit  1302  feeds the medium from the inserter tray  503 , makes a crease for a hinge, and supplies it to a conveyance path  806  of a case binding apparatus  207 . In step S 2416 , the device control unit  1302  starts printing of print data of a case binding body. The device control unit  1302  supplies the printed medium to a medium stacking unit  810  of the case binding apparatus  207 . In step S 2417 , the device control unit  1302  instructs a case binding control unit  1013  via the CPU circuit unit  1001  of the image forming apparatus  101  to form a case-bound product. Then, the device control unit  1302  ends this processing sequence. 
     By the above processing, one medium passes twice through the creaser apparatus  205  to make creases at a plurality of creasing pressures in accordance with creasing purposes. 
     Note that the third embodiment has given an explanation based on the first embodiment, but processing may be executed based on the second embodiment. In the third embodiment, a crease for a hinge is made after making a crease for a spine edge, but the order of making creases may be reversed. 
     Fourth Embodiment 
     The fourth embodiment will exemplify a case in which two creaser apparatuses in the third embodiment are connected. The fourth embodiment will exemplify a case in which a creasing die for a “crease for a spine edge (crease for a fold)” and a creasing die for a “crease for a hinge” are attached in the two creaser apparatuses, respectively. In the fourth embodiment, as in the third embodiment, there are a plurality of creasing dies. An ID (identification information) is assigned to each creasing die, and the creaser apparatus can read the ID of the creasing die. The creasing die has a mechanism of controlling a creasing pressure with respect to a medium by a spring incorporated in the die. 
     As in the third embodiment, the fourth embodiment assumes that a die for the “creasing pressure of 100 Kgf” is associated with a die ID “1”, and a die for the “creasing pressure of 140 Kgf” is associated with a die ID “2”. Since the premise of the fourth embodiment is the same as that of the first embodiment, a description of a repetitive part will be omitted, and settings and processing unique to the fourth embodiment will be explained with reference to  FIGS. 20 to 22 . 
       FIG. 20  is a sectional view showing a creaser apparatus  205  according to the fourth embodiment. Compared with  FIG. 4 , two creaser apparatuses in  FIG. 17  described in the third embodiment are connected. Pressure devices  2506  and  2515  are operable by controlling corresponding creaser control units  1011  by a CPU circuit unit  1001 . In this embodiment, a creaser apparatus that controls the pressure device  2506  includes a CPU circuit unit  1101 A, and a creaser apparatus that controls the pressure device  2515  includes a CPU circuit unit  1101 B. Assume that creaser control units  1011 A and  1011 B are connected, instead of the creaser control unit  1011  in  FIG. 7A . The remaining arrangement is the same as that in  FIG. 17  in the third embodiment, and a description thereof will not be repeated. To simplify the description, a creaser apparatus including the pressure device  2506  will be referred to as creaser A, and a creaser apparatus including the pressure device  2515  will be referred to as creaser B. 
       FIG. 21  shows a message window displayed on an operation panel  425  of an image forming apparatus  101 .  FIG. 21  shows a message displayed when a creasing die corresponding to a creasing purpose has not been attached in the creaser apparatus  205 . As an example of a message  2601 , a message that neither a creasing die (ID=1) for a spine edge nor a creasing die (ID=2) for a hinge has been attached is displayed. An OK button  2602  is a button that is pressed by the operator after confirming the message  2601 . When the operator presses the OK button  2602 , the message in  FIG. 21  disappears. A UI processing unit  1301  of the image forming apparatus  101  controls display/non-display of the message window in  FIG. 21 . 
     [Processing Sequence] 
       FIG. 22  is a flowchart showing processing to be executed by a device control unit  1302  of the image forming apparatus  101 . A program regarding this processing is stored in a ROM  1003  of the image forming apparatus  101 , and read out and executed by a CPU  1002 . Processes by an information processing apparatus  103  and an image processing apparatus  102  are the same as those in the first embodiment, and a description thereof will not be repeated. Steps S 2701  to S 2706  are the same as steps S 1801  to S 1806  of  FIG. 13  described in the first embodiment, and a description thereof will not be repeated. 
     In step S 2707 , the device control unit  1302  issues an instruction via the CPU circuit unit  1001  of the image forming apparatus  101  to obtain the IDs of creasing dies attached in the creaser apparatuses  205 . More specifically, the CPU circuit unit  1001  instructs the die detection units of the CPU circuit units  1101 A and  1101 B to obtain the IDs of attached creasing dies. Upon receiving the instruction, the die detection units of the CPU circuit units  1101 A and  1101 B send back the obtained IDs of the dies to the device control unit  1302  via the CPU circuit unit  1001 . 
     In step S 2708 , the device control unit  1302  checks whether a creasing die for a spine edge has been attached in creaser A and a die for a hinge has been attached in creaser B. When the medium ID is “1”, the target creasing pressure for a spine edge is “100 Kgf”, and the creasing pressure for a hinge is “140 Kgf”. More specifically, if the ID of the creasing die of creaser A is “1” and the ID of the creasing die of creaser B is “2” (YES in step S 2708 ), the device control unit  1302  advances to step S 2711 ; otherwise (NO in step S 2708 ), the device control unit  1302  advances to step S 2709 . 
     In step S 2709 , the device control unit  1302  instructs the UI processing unit  1301  to display the message in  FIG. 21 . In step S 2710 , the device control unit  1302  waits until the operator attaches creasing dies designed in  FIG. 21  to creaser A and creaser B. If the designated creasing dies are attached to creaser A and creaser B (YES in step S 2710 ), the device control unit  1302  advances to step S 2711 . If the designated creasing dies are not attached to creaser A and creaser B (NO in step S 2710 ), the device control unit  1302  waits until they are attached. Processes in steps S 2711  and S 2712  are the same those in steps S 1808  and S 1809  of  FIG. 13 , and a description thereof will not be repeated. 
     By the above processing, creases can be made on one medium at a plurality of creasing pressures in accordance with creasing purposes. Note that the fourth embodiment has given an explanation based on the first embodiment, but processing may be executed based on the second embodiment. In the fourth embodiment, the creasing die for a spine edge is attached in creaser A, and the creasing die for a hinge is attached in creaser B, but these creasing dies may be interchanged. Unlike the message display in  FIG. 21 , even when a creasing die is attached, it may be determined in the processing of step S 2710  that the creasing die has been attached correctly. 
     Although the image forming apparatus  101  and the image processing apparatus  102  are separate in the above-described system, the image processing apparatus  102  may be integrated into the image forming apparatus  101 . 
     Although two types of creases have been exemplified in the above-described example, three or more types of creases may be applied. In this case, it is considered to connect three creaser apparatuses. 
     Other Embodiments 
     Embodiment(s) of the present invention can also be realized by a computer of a system or apparatus that reads out and executes computer executable instructions (e.g., one or more programs) recorded on a storage medium (which may also be referred to more fully as a ‘non-transitory computer-readable storage medium’) to perform the functions of one or more of the above-described embodiment(s) and/or that includes one or more circuits (e.g., application specific integrated circuit (ASIC)) for performing the functions of one or more of the above-described embodiment(s), and by a method performed by the computer of the system or apparatus by, for example, reading out and executing the computer executable instructions from the storage medium to perform the functions of one or more of the above-described embodiment(s) and/or controlling the one or more circuits to perform the functions of one or more of the above-described embodiment(s). The computer may comprise one or more processors (e.g., central processing unit (CPU), micro processing unit (MPU)) and may include a network of separate computers or separate processors to read out and execute the computer executable instructions. The computer executable instructions may be provided to the computer, for example, from a network or the storage medium. The storage medium may include, for example, one or more of a hard disk, a random-access memory (RAM), a read only memory (ROM), a storage of distributed computing systems, an optical disk (such as a compact disc (CD), digital versatile disc (DVD), or Blu-ray Disc (BD)™), a flash memory device, a memory card, and the like. 
     While the present invention has been described with reference to exemplary embodiments, it is to be understood that the invention is not limited to the disclosed exemplary embodiments. The scope of the following claims is to be accorded the broadest interpretation so as to encompass all such modifications and equivalent structures and functions. 
     This application claims the benefit of Japanese Patent Application No. 2014-034711, filed Feb. 25, 2014, which is hereby incorporated by reference herein in its entirety.