Patent Publication Number: US-2009218747-A1

Title: Sheet processing apparatus, sheet processing apparatus control method, and computer-readable storage medium

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to a sheet processing apparatus, a sheet processing apparatus control method, and a computer-readable storage medium. 
     2. Description of the Related Art 
     A conventional electrophotographic image forming apparatus, which feeds a sheet from a sheet feed unit and forms an image on the sheet conveyed therethrough, transfers a toner image formed on a photosensitive drum onto the sheet fed from the sheet feed unit and fixes the toner image on the sheet with a fixing device. The fixing device fixes the toner image on the sheet by applying pressure and heat thereon. In this regard, the sheet may be physically curled (deformed) during fixing the toner image on the sheet. 
     If a sheet is curled, the quality of a resulting processed product may degrade. Furthermore, the maximum quantity of the sheet to be stacked on a sheet discharge tray maybe reduced. That is, if curled sheets are stacked, the total thickness of the stacked sheet bundle may become greater than that of uncurled sheet bundle. Accordingly, if curled sheets are stacked, the maximum quantity of stackable sheets may become small. Furthermore, the stability of the stacked sheet bundle may degrade. 
     In this regard, in order to correct curling of a sheet, Japanese Patent Application Laid-Open No. 2008-013284 discusses an image forming apparatus that corrects the curling of a sheet by using a curling correction roller installed in a sheet conveyance path after fixing the toner image on the sheet with a fixing device. By using the above-described conventional image forming apparatus, a user can adjust the amount of correcting curling of a sheet with the curling correction roller. 
     However, if a plurality of sheet feed units is provided, the conventional image forming apparatus or the method discussed in Japanese Patent Application Laid-Open No. 2008-013284 does not determine from which sheet feed unit the curled sheet has been fed in adjusting the sheet curling correction amount or executing other processing. 
     Accordingly, with the above-described conventional method, the user cannot easily recognize the sheet feed unit that has fed the curled sheet. Furthermore, the user cannot easily input a curling correction amount for the sheet fed from the sheet feed unit. 
     SUMMARY OF THE INVENTION 
     According to an aspect of the present invention, a sheet processing apparatus configured to convey a sheet fed from any one of a plurality of sheet feed units includes a curl detecting unit configured to detect curling of the sheet fed from any one of the plurality of sheet feed units, and a specifying unit configured to specify a sheet feed unit that has fed the sheet having the curling detected by the curl detecting unit from among the plurality of sheet feed units. 
     Further features and aspects of the present invention will become apparent from the following detailed description of exemplary embodiments with reference to the attached drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The accompanying drawings, which are incorporated in and constitute a part of the specification, illustrate exemplary embodiments, features, and aspects of the invention and, together with the description, serve to describe the principles of the present invention. 
         FIG. 1  illustrates an exemplary configuration of an image forming system according to an exemplary embodiment of the present invention. 
         FIG. 2  illustrates an exemplary configuration of an image forming apparatus according to an exemplary embodiment of the present invention. 
         FIG. 3  illustrates an exemplary configuration of an image forming apparatus according to an exemplary embodiment of the present invention. 
         FIG. 4  illustrates an example of a curling correction roller pair according to an exemplary embodiment of the present invention. 
         FIG. 5  illustrates an example of a curling correction roller pair according to an exemplary embodiment of the present invention. 
         FIG. 6  illustrates an example of a paper feed deck according to an exemplary embodiment of the present invention. 
         FIG. 7  illustrates an example of a large-capacity stacker according to an exemplary embodiment of the present invention. 
         FIG. 8  illustrates an exemplary configuration of a saddle stitch binding machine according to an exemplary embodiment of the present invention. 
         FIG. 9  illustrates an example of an operation unit according to an exemplary embodiment of the present invention. 
         FIG. 10  illustrates an example of a display screen displayed on a touch panel according to an exemplary embodiment of the present invention. 
         FIG. 11  illustrates an example of a display screen displayed on the touch panel according to an exemplary embodiment of the present invention. 
         FIG. 12  illustrates an example of a display screen displayed on the touch panel according to an exemplary embodiment of the present invention. 
         FIG. 13  is a flowchart illustrating exemplary control processing according to an exemplary embodiment of the present invention. 
         FIG. 14  is a flowchart illustrating exemplary control processing according to an exemplary embodiment of the present invention. 
         FIG. 15  illustrates an example of a job management table displayed on the touch panel according to an exemplary embodiment of the present invention. 
         FIG. 16  illustrates an example of a display screen displayed on the touch panel according to an exemplary embodiment of the present invention. 
         FIG. 17  illustrates an example of a display screen displayed on the touch panel according to an exemplary embodiment of the present invention. 
         FIG. 18  illustrates an example of a display screen displayed on the touch panel according to an exemplary embodiment of the present invention. 
         FIG. 19  illustrates a sheet discharge operation according to an exemplary embodiment of the present invention. 
         FIG. 20  illustrates an example of a job management table according to an exemplary embodiment of the present invention. 
         FIG. 21  illustrates an example of a display screen displayed on the touch panel according to an exemplary embodiment of the present invention. 
         FIG. 22  illustrates an example of a display screen displayed on the touch panel according to an exemplary embodiment of the present invention. 
         FIG. 23  illustrates a sheet discharge operation according to an exemplary embodiment of the present invention. 
         FIG. 24  illustrates an example of a job management table according to an exemplary embodiment of the present invention. 
         FIG. 25  is a flowchart illustrating exemplary control processing according to an exemplary embodiment of the present invention. 
         FIG. 26  is a flow chart illustrating exemplary control processing according to an exemplary embodiment of the present invention. 
         FIG. 27  illustrates an example of a display screen displayed on the touch panel according to an exemplary embodiment of the present invention. 
         FIG. 28  illustrates a sheet discharge operation according to an exemplary embodiment of the present invention. 
         FIG. 29  illustrates an example of a job management table according to an exemplary embodiment of the present invention. 
         FIG. 30  illustrates an example of a display screen displayed on the touch panel according to an exemplary embodiment of the present invention. 
         FIG. 31  illustrates a sheet discharge operation according to an exemplary embodiment of the present invention. 
         FIG. 32  illustrates an example of a display screen displayed on the touch panel according to an exemplary embodiment of the present invention. 
         FIG. 33  illustrates exemplary program code according to an exemplary embodiment of the present invention. 
     
    
    
     DETAILED DESCRIPTION OF THE EMBODIMENTS 
     Various exemplary embodiments, features, and aspects of the present invention will now be herein described in detail below with reference to the drawings. It is to be noted that the relative arrangement of the components, the numerical expressions, and numerical values set forth in these embodiments are not intended to limit the scope of the present invention. 
     A first exemplary embodiment of the present invention will be described in detail below.  FIG. 1  illustrates an exemplary configuration of an image forming system  1000  according to the present exemplary embodiment. The image forming system  1000  includes an image forming apparatus  100 , to which a paper feed deck  50   a,  a paper feed deck  50   b,  a large-capacity stacker  200   a,  a large-capacity stacker  200   b,  and a saddle stitch binding machine  200   c  are connected. 
       FIG. 2  illustrates an exemplary inner configuration of the image forming apparatus  100  of the image forming system  1000  according to the present exemplary embodiment. The image forming apparatus  100  illustrated in  FIG. 1  is also illustrated in  FIG. 2 . Referring to  FIG. 2 , a paper feed deck  50  includes the paper feed decks  50   a  and  50   b  illustrated in  FIG. 1 . A sheet processing apparatus  200  includes the large-capacity stackers  200   a  and  200   b  and the saddle stitch binding machine  200   c,  which are illustrated in  FIG. 1 . 
     The image forming apparatus  100  includes a control unit  201 , a scanner unit  202 , an operation unit  203 , a compression/decompression unit  204 , a read-only memory (ROM)  205 , a random access memory (RAM)  206 , a printer unit  207 , a hard disk drive (HDD)  208 , and an external interface (I/F) unit  209 , which are in communication with one another. 
     The control unit  201  centrally controls the operation of and processing executed by the image forming system  1000 . The ROM  205  stores a program loaded and executed by the control unit  201 . The RAM  206  is used as a work area for the control unit  201 . Furthermore, the RAM  206  stores a control table used in executing control processing. 
     The operation unit  203  includes a liquid crystal display (LCD) unit and a touch panel. The operation unit  203  can receive an instruction from a user and display a message to the user. The scanner unit  202  reads an image of a document and generates image data of the read document. The printer unit  207  prints the image data. The compression/decompression unit  204  performs compression and decompression processing on image data based on various compression formats, such as Joint Bi-level Image Experts Group (JBIG) or Joint Photographic Experts Group (JPEG). 
     The HDD  208  stores the image data read with the scanner unit  202  and page description language (PDL) data received from an external apparatus, such as a personal computer (PC), via the external I/F unit  209 . 
     The control unit  201  of the image forming apparatus  100  executes a job, such as a copy job or a print job, by loading and executing the program from the ROM  205 . Here, a “copy job” is a job for forming an image with the printer unit  207  based on the image data read with the scanner unit  202  according to a setting received from the operation unit  203 . A “print job” is a job for forming an image with the printer unit  207  based on the image data received via the external I/F unit  209  according to a print setting that has been associated with and set on the image data. 
     Now, an image forming operation performed according to an instruction from the control unit  201  will be described in detail below with reference to a cross section of the image forming system  1000  illustrated in  FIG. 3 .  FIG. 3  is a cross section that illustrates an example of the image forming apparatus  100 , the paper feed deck  50 , and the sheet processing apparatus  200  according to the present embodiment. 
     In the present exemplary embodiment, the image forming apparatus  100  is a 1D (single-drum) type color multifunction peripheral (MFP). However, the present invention is not limited to this. That is, a monochromatic MFP or a 4D (four-drum) type MFP can be used as the image forming apparatus  100 . 
     Referring to  FIG. 3 , an auto document feeder (ADF)  301  separates a document set on a stacking surface of a document tray page by page from the first page. Then, the ADF  301  feeds the document onto a document positioning glass to scan the document with a reading unit  302 . The reading unit  302  reads an image on the document that has been conveyed onto the document positioning glass and converts the read document image into image data with an image sensor, such as a charge-coupled device (CCD). 
     A ray, such as a laser beam, which has been modulated according to the image data, is made incident on a rotating polygonal mirror  303 . The ray reflected from the rotating polygonal mirror  303  then falls on the surface of a photosensitive drum  304  via a reflection mirror as reflection scanning light to form a latent image on the surface of the photosensitive drum  304 . The latent image formed on the surface of the photosensitive drum  304  with the ray is then developed with toner. 
     Furthermore, the image forming apparatus  100  conveys a sheet fed from any one of paper feed cassettes  401  through  408 , each of which is an example of a paper feed unit, to a registration roller  316 . The image forming apparatus  100  further conveys the sheet onto a transfer drum  305  to transfer the toner image on the photosensitive drum  304  onto the sheet on the transfer drum  305 . 
     By serially performing a series of image forming processing on toners of colors of yellow (Y), magenta (M), cyan (C), and black (K), a full color image is formed. After performing four-image forming processing, a sheet on the transfer drum  305 , onto which a full color image has been formed, is then separated from the transfer drum  305  by a separation claw  306 . Then, the separated sheet is conveyed to a fixing device  308  by a pre-fixing conveyance unit  307 . 
     The fixing device  308  includes rollers and a belt in combination with one another. Furthermore, the fixing device  308  includes therein a heat source such as a halogen heater. The fixing device  308  applies heat and pressure to the toner on the sheet having the transferred toner image. Thus, the toner on the sheet having the toner image is fused and fixed. 
     A sheet discharge flapper  309  can swing around an axis. The sheet discharge flapper  309  swings to regulate the direction of conveying a sheet. When the sheet discharge flapper  309  swings clockwise in  FIG. 3 , the sheet is conveyed in a straight direction. Then, the sheet is conveyed to a paper discharge roller  310  and is then discharged to the large-capacity stacker  200   a  by the paper discharge roller  310 . 
     On the other hand, in forming images on both sides of the sheet (two-sided printing), the sheet discharge flapper  309  swings counterclockwise in  FIG. 3  to change the path for conveying the sheet to a downward direction. Thus, the sheet is conveyed to a two-sided conveyance unit. The two-sided conveyance unit includes a reversal flapper  311 , a reversal roller  312 , a reversal guide  313 , and a two-sided tray  314 . 
     The reversal flapper  311  swings around an axis and regulates the direction of conveying the sheet. In performing a two-sided print job, the control unit  201  performs the following control. That is, the control unit  201  performs control so that the reversal flapper  311  swings counterclockwise in  FIG. 3  to convey the sheet, whose first surface has been already printed, into the reversal guide  313  via the reversal roller  312 . 
     Then, the control unit  201  temporarily stops the reversal roller  312  in the state where a trailing edge of the sheet is pinched by a reversal roller  324 . Then, the control unit  201  allows the reversal flapper  311  to swing counterclockwise in  FIG. 3 . Furthermore, the control unit  201  allows the reversal roller  324  to rotate in a reverse direction. 
     As described above, the control unit  201  performs control so that the sheet is switched back to be conveyed. The control unit  201  performs control to guide the sheet to the two-sided tray  314  in the state where the leading edge and trailing edge of the sheet have been changed in position. 
     The two-sided tray  314  temporarily stacks the sheet that has been conveyed thereto as described above. Then, the sheet temporarily stacked on the two-sided tray  314  is conveyed again to the registration roller  316  by a paper refeed roller  315 . At this time, the sheet is fed with a surface thereof opposite to the first surface used in the transfer processing facing the photosensitive drum  304 . 
     Then, the control unit  201  performs control to form an image on the second surface of the sheet as in the processing described above. 
     Thus, images are formed on both sides of the sheet. Then, the sheet having the image formed thereon is subjected to fixing processing by the fixing device  308 . After that, the sheet having the image fixed thereon is conveyed to the paper discharge roller  310  again and conveyed to the large-capacity stacker  200   a  via the paper discharge roller  310 . 
     In the image forming apparatus  100 , which forms an image by electrophotographic processing, a sheet may be physically curled during fixing the toner on the sheet with the fixing device  308 . A sheet may be curled when the toner that has been transferred on the sheet is fused by the heat applied by the fixing device  308  and is later condensed after the heated toner is cooled down. In this regard, the present exemplary embodiment corrects the curling of the sheet on which the toner has been fixed by the fixing device  308  with the curling correction roller pairs  340  and  341 . 
     The amount of curling of a sheet may differ according to the type of the sheet. Therefore, the amount of curling corrected with the curling correction roller pairs  340  and  341  should be changed according to the type of the sheet. In this regard, the present exemplary embodiment allows the user to set the curling correction amount independently and differently for each paper feed cassette by operating the operation unit  203 . Thus, the user can correct the curling of the sheet according to the curling correction amount differently and appropriately set for each paper feed cassette. 
     In the present exemplary embodiment, the curling of the sheet fed from the paper feed cassettes is corrected by two types of curling correction roller pairs. Among the two types of curling correction roller pairs, the upward curling correction roller pair  341  applies the correction force for bending both edges of the sheet downward to the sheet in the sheet conveyance direction to correct upward curling of the sheet, in which both edges of the sheet are curled upward in the sheet conveyance direction. On the other hand, the downward curling correction roller pair  340  applies the correction force for bending both edges of the sheet upward to the sheet in the sheet conveyance direction to correct downward curling of the sheet, in which both edges of the sheet are curled downward in the sheet conveyance direction. 
     The upward curling correction roller pair  341  will be described in detail below with reference to  FIG. 4 . 
     Referring to  FIG. 4 , the upward curling correction roller pair  341  is constituted by a sponge roller  501  having a soft surface and a lower roller  502 , which is pressed against and engages in the sponge roller  501 . A roller shaft  503  of the sponge roller  501  is urged upward against a frame (not illustrated) by an urging unit (not illustrated). The roller shaft  503  can be moved in a vertical direction while being supported by the frame. 
     A bearing  504  contacts the roller shaft  503  from above. An eccentric cam  505  contacts the bearing  504  from above. When the eccentric cam  505  rotates around the shaft  506  from a position illustrated in  FIG. 4 , the bearing  504  is pressed downward due to the shape of the eccentric cam  505 . At the same time, the roller shaft  503  is pressed down, together with the sponge roller  501 , against the urging force from the urging unit and the lower roller  502  engages in the sponge roller  501 . 
     Note that when the eccentric cam  505  is rotated by 180°, the amount of engagement of the lower roller  502  into the sponge roller  501  becomes maximum as illustrated in  FIG. 5 . 
     That is, in the present exemplary embodiment, the vertical position of the roller shaft  503  is determined by adjusting the rotational angle of the eccentric cam  505 . Thus, the amount of engagement of the lower roller  502  into the sponge roller  501  can be changed (adjusted). Furthermore, the curling correction amount (the correction force) can be changed by changing the amount of engagement as described above. 
     Note that in the example illustrated in  FIG. 4 , the eccentric cam  505  is positioned at a state before correcting the curling amount. In the present exemplary embodiment, the amount of engagement is changed by driving the eccentric cam  505  by 12° at a time, for example, starting from the position. The upward curling correction roller pair  341  operates in the above-described manner. The downward curling correction roller pair  340  has a configuration substantially similar to that of the upward curling correction roller pair  341  and operates in substantially the same manner except that in the downward curling correction roller pair  340 , the sponge roller  501  and the lower roller  502  are provided at the opposite positions in the vertical direction. 
     Meanwhile, the larger the amount of toner fixed on a sheet is, the greater the amount of curling that may occur as the time passes may become. In this regard, in order to reduce the amount of curling that may occur after a predetermined length of time has elapsed, the present exemplary embodiment outputs a printed sheet after applying reverse curling to the printed sheet if the sheet is curled, by using either one of the upward curling correction roller pair  341  and the downward curling correction roller pair  340 . Thus, the present exemplary embodiment can prevent a sheet from being curled after a predetermined length of time has elapsed. 
     In the present exemplary embodiment, the amount of engagement of the curling correction roller pair can be set at a plurality of levels. Thus, the present exemplary embodiment changes the amount of engagement according to the amount of curling to be corrected. More specifically, the amount of engagement can be controlled at fifteen levels by driving the eccentric cam  505  by 12° at a time. Furthermore, if the amount of engagement is set at the level  15 , a maximum reverse curling can be applied to a curled sheet. 
     Now, an exemplary configuration of the paper feed deck  50   a  will be described in detail below with reference to  FIG. 6 . 
     The paper feed deck  50   a  includes paper feed cassettes  403  through  405 . The paper feed deck  50   a  feeds a sheet from any one of the paper feed cassettes  403  through  405  according to an instruction from the control unit  201 . Hereinbelow, the sheet feeding operation performed by the paper feed deck  50   a  will be described in detail below with reference to the cross section of the paper feed deck  50   a  illustrated in  FIG. 6 . 
     In feeding a sheet from the paper feed cassette  403 , of the paper feed cassettes  403  through  405 , the control unit  201  picks up a sheet by rotating a paper feed roller  423  and conveys the sheet to an upper vertical path  415 . After conveying the sheet into the upper vertical path  415 , the control unit  201  then performs control so that the sheet is conveyed into a buffer path  412  via a straight path  413 . Then, the sheet is conveyed into the sheet conveyance path of the image forming apparatus  100 . After entering the image forming apparatus  100 , the sheet is conveyed to the registration roller  316 . The operation to be performed thereafter is the same as the operation for feeding a sheet from the paper feed cassette  401 . Accordingly, the detailed description thereof will not be repeated here. 
     In feeding a sheet from the paper feed cassette  404 , the control unit  201  picks up a sheet by rotating a paper feed roller  424  and conveys the sheet to a lower vertical path  416 . After conveying the sheet into the lower vertical path  416 , the control unit  201  then performs control so that the sheet is conveyed into the buffer path  412  via the straight path  413 . Then, the sheet is conveyed into the sheet conveyance path of the image forming apparatus  100 . After entering the image forming apparatus  100 , the sheet is conveyed to the registration roller  316 . The operation to be performed thereafter is the same as the operation for feeding a sheet from the paper feed cassette  401 . Accordingly, the detailed description thereof will not be repeated here. 
     In feeding a sheet from the paper feed cassette  405 , the control unit  201  picks up a sheet by rotating a paper feed roller  425  and conveys the sheet to the lower vertical path  416  in the above-described manner. 
     Furthermore, if double feeding of sheets has occurred, the paper feed deck  50   a  detects the double feeding state with a double feed detection sensor  417 . Here, “double feeding” refers to a state in which a plurality of sheets is fed at the same time in an overlapping state. The double feed detection sensor  417  transmits a signal indicating that the double feeding has occurred to the control unit  201 . After receiving the signal, the control unit  201  discharges the double-fed sheet onto an escape tray  411  via an escape path  410 . 
     The paper feed deck  50   b  has a configuration similar to that of the paper feed deck  50   a.  The paper feed deck  50   b  feeds a sheet from any one of paper feed cassettes  406  through  408  according to an instruction from the control unit  201 . Then, the paper feed deck  50   b  conveys the sheet into an upper vertical path or a lower vertical path. Furthermore, the paper feed deck  50   b  conveys the sheet to a cascade path  414  of the paper feed deck  50   a  via a straight path and a buffer path. 
     After having been conveyed to the cascade path  414  of the paper feed deck  50   a,  the sheet is conveyed to the buffer path  412  via the straight path  413 . Then, the sheet is conveyed to the registration roller  316  via the conveyance path of the image forming apparatus  100 . The operation to be performed thereafter is the same as the operation for feeding the sheet from the paper feed cassette  401 . Accordingly, the detailed description thereof will not be repeated here. 
     As described above, the image forming system  1000  can feed a sheet from any one of the paper feed cassettes  401  through  408 . 
     Now, an exemplary configuration of the large-capacity stacker  200   a  will be described in detail below with reference to  FIG. 7 .  FIG. 7  is a cross section illustrating an example of a configuration of the large-capacity stacker  200   a  according to the present exemplary embodiment. 
     Referring to  FIG. 7 , the large-capacity stacker  200   a  conveys the sheet that has been conveyed from an upstream apparatus selectively into a straight path  253 , an escape path  251 , or a stack path  252 . The straight path  253  is a conveyance path for transferring the sheet that has been received from an upstream apparatus to a downstream apparatus. The escape path  251  is the conveyance path for conveying the sheet onto an escape tray  257 . The escape path  251  is used in executing a verification operation (proof printing) for verifying the finishing state of the printed sheet, for example. The stack path  252  is a conveyance path for discharging the sheet on a stack tray. 
     Note that a plurality of sensors (not illustrated), which is used to detect a status of conveyance of the sheet and paper jamming, if any, is provided in the sheet conveyance path in the large-capacity stacker  200   a.  More specifically, curling amount detection sensors  701  and  702  and a tray full stack state detection sensor  703  are located at positions opposing the surface of the sheets stacked on a stack tray  254 . 
     The control unit  201  receives a signal received from the sensors via a signal line provided between the sheet processing apparatus  200  and the control unit  201  ( FIG. 2 ). The control unit  201  recognizes the conveyance state of the sheet and paper jamming, if any, inside the large-capacity stacker  200   a  according to the received signal to control the large-capacity stacker  200   a.    
     The stack tray  254  is a stacking unit provided on an extendable stay  255 . The stack tray  254  stacks the sheets that have been designated to be stacked on the large-capacity stacker  200   a.  The control unit  201  discharges and stacks the sheet that has been designated to be discharged on the large-capacity stacker  200   a  on the stack tray  254  via the stack path  252 . A wagon  256  is provided below the extendable stay  255 . If a handle (not illustrated) is mounted on the wagon  256 , the user can carry the stacked output product contained thereon to another offline finisher. 
     The large-capacity stacker  200   a  includes a front door as illustrated in  FIG. 1 . By opening the front door, the user can take out the sheet stacked in the large-capacity stacker  200   a.  Furthermore, the large-capacity stacker  200   a  includes a sensor for detecting the open/closed state of the front door. The control unit  201  elevates the extendable stay  255  to a position appropriate for stacking the output product when the front door is closed according to a signal from the sensor. 
     Furthermore, the control unit  201  descends the stack tray  254  by controlling the extendable stay  255  every time a sheet is stacked on the stack tray  254 . Thus, the sheet discharged from the stack path  252  can be stacked on the top of the sheet bundle stacked on the stack tray  254 . If the stack state detection sensor  703  has detected that the stack tray  254  has been descended to a position of the stack state detection sensor  703 , the stack state detection sensor  703  transmits a tray-full signal to the control unit  201 . Here, the “tray-full signal” indicates that the number of stacked sheets has reached a predetermined quantity and thus the stack tray  254  is in a fully stacked state. 
     When the tray-full signal is received from the tray full stack state detection sensor  703 , the control unit  201  recognizes that the stack tray  254  is in a fully stacked state. Furthermore, if the front door has been opened by the operator (user) or if the user has instructed to open the front door, the control unit  201  descends the stack tray  254 . 
     The control unit  201  determines the amount of curling of the sheets stacked on the stack tray  254  by using the curling detection sensors  701  and  702 . The curling detection sensors  701  and  702  can be moved in the sheet conveyance direction. The control unit  201  moves the curling detection sensor  701  to a position for detecting an edge of the sheet according to the size of the sheet to be printed while moving the curling detection sensor  702  to a position for detecting the center of the sheet. The curling detection sensors  701  and  702  each transmit a detected value to the control unit  201 . 
     The curling detection sensors  701  and  702  each measure and detect the total thickness of the sheet bundle on the stack tray  254  at the corresponding positions of the sheet every time another sheet is stacked on the stack tray  254 . Then, the curling detection sensors  701  and  702  each transmit the result of the measurement to the control unit  201 . 
     The control unit  201  determines the amount of curling of the sheet according to the difference between the distances (thickness values) detected by the curling detection sensors  701  and  702 . The control unit  201  determines that the sheet is curled (that excessive curling has occurred) if the amount of curling of the sheet is greater than a predetermined curling amount. 
       FIG. 8  illustrates an exemplary configuration of the saddle stitch binding machine  200   c  according to the present exemplary embodiment. 
     The saddle stitch binding machine  200   c  executes stapling processing, cutting processing, punching processing, and folding processing on the sheet that has been conveyed from the image forming apparatus  100 . 
     Note that a plurality of sheet detection sensors for detecting the state of conveyance of the sheet or paper jamming, if any, is provided in the sheet conveyance path in the saddle stitch binding machine  200   c.  Each of the sensors transmits detected information to the control unit  201  via a signal line for data communication with the control unit  201  provided between the sheet processing apparatus  200  and the control unit  201  ( FIG. 2 ). The control unit  201  recognizes the conveyance state of the sheet and paper jamming, if any, inside the saddle stitch binding machine  200   c  according to the signal received from the saddle stitch binding machine  200   c  to control the saddle stitch binding machine  200   c.    
     If another sheet processing apparatus is provided between the saddle stitch binding machine  200   c  and the image forming apparatus  100 , the sensors each transmit detected information about the large-capacity stacker to the control unit  201  via a signal line provided to the sheet processing apparatus. 
     Referring to  FIG. 8 , the saddle stitch binding machine  200   c  includes a sample tray  281 , an output tray  282 , and a booklet tray  283 . The control unit  201  performs control for switching the unit (tray) to be used according to the type of the job and the number of recording sheets to be discharged. 
     In executing stapling processing, the saddle stitch binding machine  200   c  performs control for conveying the sheet that has been transmitted from the large-capacity stacker  200   b  onto the output tray  282 . The saddle stitch binding machine  200   c  serially stacks the sheets on the processing tray  284 , which is provided within the saddle stitch binding machine  200   c,  and binds the sheet bundle with a stapler  285  on the processing tray  284  before outputting the bound sheets onto the output tray  282 . 
     In addition, the saddle stitch binding machine  200   c  includes a z-folding machine  292  and a puncher  286 . The z-folding machine  292  folds the sheet in a z-like shape. The puncher  286  provides two (or more) holes on the sheet used for filing the print product. The z-folding machine  292  and the puncher  286  each execute respective processing operations according to the print setting where necessary. The sheet that has been processed as described above is then conveyed through the saddle stitch binding machine  200   c  and discharged on the paper discharge tray, such as the output tray  282  or the sample tray  281 . 
     The saddle stitcher unit  287  stacks a plurality of sheets. Furthermore, the saddle stitcher unit  287  folds the sheet bundle in two by causing the center of the sheet bundle to engage the roller after binding the stacked sheet bundle at two positions at the center thereof. Thus, the saddle stitch binding machine  200   c  executes the saddle stitching binding processing for generating a bookbound print product, such as a brochure. The sheet bundle bound with the saddle stitcher unit  287  is discharged onto the booklet tray  283 . 
     Furthermore, an inserter  293  is used for conveying the sheet set on an inserter tray  291  to the output tray  282 , the sample tray  281 , or the saddle stitcher unit  287 . Thus, the sheet set on the inserter  293  can be inserted between the sheets to be conveyed from the image forming apparatus  100  into the saddle stitch binding machine  200   c.    
     Furthermore, the saddle stitch binding machine  200   c  includes a cutting unit  288 . The bookbound print product discharged from the saddle stitcher unit  287  onto the booklet tray  283  is then conveyed to the cutting unit  288 . In this case, the bookbound print product is fed by the roller by a predetermined length. Then, the bookbound print product is cut by a cutter unit  289  by a predetermined length. Then, the cut bookbound print product is stacked on a booklet holding unit  290 . 
     Now, an exemplary configuration of the operation unit  203  will be described in detail below with reference to  FIG. 9 .  FIG. 9  illustrates an exemplary configuration of the operation unit  203  according to the present exemplary embodiment. 
     Referring to  FIG. 9 , the operation unit  203  includes a touch panel unit  203   a  and a key input unit  203   b.  The touch panel unit  203   a  is constituted by an LCD and a transparent electrode attached on the LCD. The touch panel  203   a  displays various setting screens used for receiving an instruction from the operator. 
     That is, the touch panel  203   a  not only functions to display various setting screens but also functions to input an instruction to receive an instruction from the user. The screen displayed on the touch panel  203   a  is displayed by executing a display program previously stored on the ROM  205  with the control unit  201 . 
     The key input unit  203   b  includes a power key  901 , a start key  903 , a stop key  902 , a reset key  904 , an operator mode key  905 , a numeric keypad  906 , and a clear key  907 . Here, the start key  903  can be operated by the operator to issue an instruction for starting a copy job or a send job by the printing apparatus  100 . The numeric keypad  906  can be operated by the operator to enter a numerical value for a print setting item, such as the number of print copies. The clear key  907  can be operated by the operator to clear various parameters set with the numeric keypad  906 . 
     In executing a copy job, the control unit  201  instructs the paper feed cassette on which the sheets of the size and the type that have been set by the user to feed a sheet. The paper feed cassette to which the instruction has been issued then feeds a sheet. Furthermore, it is also useful if the user can directly designate a paper feed cassette instead of designating the size and the type of the sheet. In this case, the control unit  201  instructs the designated paper feed cassette to feed a sheet. 
     In addition, by operating the operation unit  203 , the user can adjust the curling correction amount separately and independently on each paper feed cassette.  FIG. 10  illustrates an example of a screen displayed on the operation unit  203  when the user has pressed the user mode key  905 . 
     When a button  3501  is pressed by the user on the screen illustrated in  FIG. 10 , a screen illustrated in  FIG. 11  is displayed on the operation unit  203 . 
     The screen illustrated in  FIG. 11  is a screen for selecting the paper feed cassette, of a plurality of paper feed cassettes of the image forming system  1000 , whose curling correction amount is to be adjusted with the curling correction roller pairs  340  and  341 . Sheet feed unit buttons  1  through  8  respectively correspond to the paper feed cassettes  401  through  408 . When the user presses the button corresponding to the paper feed unit whose amount of curling correction is to be adjusted with the curling correction roller pairs  340  and  341 , of the paper feed unit buttons  1  through  8 , a screen illustrated in  FIG. 12  is displayed on the operation unit  203 . 
     The screen illustrated in  FIG. 12  is a screen for setting the curling correction amount with respect to the curling correction roller pairs  340  and  341 . The user adjusts the curling correction amount by operating a button  3703  (including a “+” (increase) key and a “−” (decrease) key) on the screen illustrated in  FIG. 12 . In the screen illustrated in  FIG. 12 , a default value (the curling correction value: “0”) is set. 
     Suppose here, for example, that the user has pressed the paper feed unit button  1  via the screen illustrated in  FIG. 11  and has set a parameter “+10” as the curling correction value by pressing the button  3703  via the screen illustrated in  FIG. 12 . In this case, the control unit  201  stores the curling correction value “+10” on the RAM  206  in association with the paper feed cassette  401 , which corresponds to the paper feed unit button  1 . 
     The control unit  201  rotates the eccentric cam  505  by the amount corresponding to the set curling correction value when the sheet fed from the paper feed cassette  401  is conveyed through the curling correction roller pairs  340  and  341 . If a value “+10” is set as the curling correction value, the control unit  201  rotates the eccentric cam  505  ( FIG. 5 ) of the upward curling correction roller pair  341  by 120° (i.e., 12°×10) from a position at which the rotational angle of the eccentric cam  505  is 0° (the state in which the lower roller  502  has not been engaged into the sponge roller  501 ). At the same time, the control unit  201  performs control so that the amount of engagement of the downward curling correction roller pair  340  into the sponge roller  501  becomes “0”. 
     On the other hand, suppose here, for example, that the user has operated the button  3703  to set a value “−5” as the curling correction value. In this case, the control unit  201  stores the curling correction value “−5” on the RAM  206  in association with the paper feed cassette  401 , which corresponds to the paper feed unit button  1 . 
     The control unit  201  rotates the eccentric cam  505  by the amount corresponding to the set curling correction value when the sheet fed from the paper feed cassette  401  is conveyed through the curling correction roller pairs  340  and  341 . If a value “−5” is set as the curling correction value, the control unit  201  rotates the eccentric cam  505  ( FIG. 5 ) of the downward curling correction roller pair  340  by 60° (i.e., 12°33 5) from a position at which the rotational angle of the eccentric cam  505  is 0°. At the same time, the control unit  201  performs control so that the amount of engagement of the upward curling correction roller pair  341  into the sponge roller  501  becomes “0”. 
     With the above-described configuration, the present exemplary embodiment can allow the user to input a curling correction value for the curling correction roller pairs  340  and  341  separately and differently for each of a plurality of paper feed units of the image forming system  1000 . 
     Now, an exemplary control by the control unit  201  for executing a job according to the first exemplary embodiment of the present invention will be described in detail below. Processing illustrated in the flow chart in  FIGS. 13 and 14  is executed with the control unit  201  by loading and executing the program stored on the ROM  205 . A job management table illustrated in  FIG. 15  is stored on the RAM  206  and used for managing information about a job that has been instructed by the user to be executed. 
     The job management table manages various information about the received job. The various information managed with the job management table includes a job number, a job name, the status of the job, a paper feed cassette used in the job, or a sheet discharge destination designated in the job. The content of the information is managed by the control unit  201 . 
     Referring to  FIG. 13 , in step S 2501 , the control unit  201  determines whether a job to be processed, such as a scan job or a print job, exists. The control unit  201  determines that a job to be processed exists if the user has pressed the start key  903  of the operation unit  203 , for example. Furthermore, the control unit  201  determines that a job to be processed exists if the control unit  201  has received a print job from the external I/F unit  209  and if the print job has been stored on a print queue as the data to be printed. If a job to be processed exists in step S 2501  (YES in step S 2501 ), then the processing advances to step S 2502 . 
     On the other hand, if no job to be processed exists in step S 2501  (NO in step S 2501 ), then the processing returns to step S 2501  to repeat the processing therein and wait until a job to be processed is received. 
     In step S 2502 , the control unit  201  refers to the print setting of the job to be processed. Then, the control unit  201  issues a sheet feeding instruction to the paper feed cassette indicated and specified in the print setting. At this time, the control unit  201  records paper feed cassette information indicating the paper feed cassette to which the sheet feeding instruction has been issued in a “paper feed cassette used” field of the job management table ( FIG. 15 ). 
     In step S 2503 , the control unit  201  forms an image on the fed sheet. If the job to be processed is a copy job, then the control unit  201  reads an image of the document with the scanner unit  202  and executes the image forming operation described above with reference to  FIG. 3  with the operation unit  203  according to the set print setting. 
     On the other hand, if the job to be processed is a print job, then the control unit  201  receives image data via the external I/F unit  209  and executes the image forming operation described above with reference to  FIG. 3  with the operation unit  203  according to the print setting associated with the image data. 
     In step S 2504 , the control unit  201  discharges the sheet having an image formed thereon to the paper discharge unit designated in the print setting. If the user has set the setting so that the sheet is to be discharged to the large-capacity stacker, then the control unit  201  discharges the sheet having an image formed thereon by the image forming apparatus  100  to the large-capacity stacker. 
     On the other hand, if the user has set the setting so that the sheet is to be discharged to the saddle stitch binding machine  200   c,  then the control unit  201  discharges the sheet having an image formed thereon by the image forming apparatus  100  to the saddle stitch binding machine  200   c.    
     In step S 2505 , the control unit  201  determines whether a tray full stack state has occurred on the stack tray  254  of the large-capacity stacker according to a tray-full signal transmitted from the tray full stack state detection sensor  703 . If it is determined according to the signal from the stack state detection sensor  703  that no tray full stack state has occurred in step S 2505  (NO in step S 2505 ), then the control unit  201  suspends the paper feeding operation. Then, the processing advances to step S 2506 . 
     On the other hand, if it is determined in step S 2505  that a tray full stack state has occurred (YES in step S 2505 ), then the processing advances to step S 2601  in  FIG. 14 , which is continued from  FIG. 13  by indicating the continued processing with a continued processing reference numeral “1” indicated with a circle in  FIGS. 13 and 14 . 
     In step S 2506 , the control unit  201  determines whether the printing of designated pages has been completed. If the printing of designated pages has been completed in step S 2506  (YES in step S 2506 ), then the processing ends. On the other hand, if the printing of designated pages has not been completed yet, the processing returns to step S 2502 . 
     As described above, if it is determined that a tray full stack state has occurred on the stack tray  254  of the large-capacity stacker, then the processing advances to step S 2601  in  FIG. 14 . 
     In step S 2601 , the control unit  201  determines whether any sheet has been curled to cause the tray full stack state according to the signal from the curling detection sensors  701  and  702 . More specifically, in step S 2601 , the control unit  201  determines the amount of curling of the sheet according to the signal from the curling detection sensors  701  and  702 . If the determined sheet curling amount is greater than a predetermined sheet curling amount, then the control unit  201  determines that the curling of the sheet has caused the tray full stack state. If it is determined in step S 2601  that the curling of the sheet has caused the tray full stack state (YES in step S 2601 ), then the processing advances to step S 2602 . In step S 2602 , the control unit  201  determines whether any job is currently being executed. 
     If it is determined that no job is currently being executed in step S 2602  (NO in step S 2602 ), then the processing advances to step S 2603 . In step S 2603 , the control unit  201  displays a message ( FIG. 18 ) on the operation unit  203  indicating that the stack tray  254  is in a tray full stack state (i.e., that the stack tray  254  is full of or almost full of sheets stacked thereon). In this regard, it is also useful if the control unit  201  displays a message indicating that the curling of the sheet has caused the tray full stack state on the operation unit  203 . With this configuration, the present exemplary embodiment can allow the user to clearly distinguish between the causes for the tray full stack state. 
     On the other hand, if a job is currently being executed in step S 2602  (YES in step S 2602 ), then the processing advances to step S 2604 . In step S 2604 , the control unit  201  specifies (identifies) the paper feed cassette used in the current job according to the job management table illustrated in  FIG. 15 . 
     In step S 2605 , the control unit  201  displays a message illustrated in  FIG. 16  on the operation unit  203  to prompt the user to enter a curling correction value for the paper feed cassette specified in step S 2604 . 
     If the user presses a curling correction button  3903  via the screen illustrated in  FIG. 16 , then a screen illustrated in  FIG. 17  is displayed on the operation unit  203 . The control unit  201  performs control so that the color of a button  3601 , which corresponds to the paper feed cassette specified in step S 2604 , is displayed in a color different from those of the other paper feed unit buttons. Accordingly, the user can easily recognize the paper feed cassette whose curling of the sheet is to be corrected. 
     Referring to  FIG. 17 , when the button  3601  is selected and the setting button  3602  is pressed by the user, the control unit  201  displays the screen illustrated in  FIG. 12  on the operation unit  203 . The user can adjust the curling correction amount for the paper feed cassette  401  corresponding to the paper feed unit button  3601  via the screen illustrated in  FIG. 12 . If an OK button illustrated in  FIG. 12  is pressed by the user and a “resume printing” button  3902  illustrated in  FIG. 16  is pressed by the user, then the processing advances to step S 2606  ( FIG. 14 ) and the control unit  201  resumes printing. 
     In step S 2606 , the control unit  201  determines whether the tray full stack state of the stack tray  254  has been solved. If a tray-full signal is no longer transmitted from the stack state detection sensor  703 , then the control unit  201  determines that the tray full stack state has been solved. If it is determined in step S 2606  that the tray full stack state has been solved (YES in step S 2606 ), then the processing advances to step S 2506  ( FIG. 13 ), which is continued from the processing illustrated in  FIG. 14  and indicated with a processing continuation reference numeral “ 2 ” indicated with a circle in  FIGS. 14 and 13 . 
     Note that in step S 2605 , the control unit  201  suspends resuming the printing until the “resume printing” button  3902  is pressed by the user, as described above. However, the present invention is not limited to this. That is, it is also useful if the processing advances to step S 2606  instead of waiting for the button  3902  to be pressed and the control unit  201  continues the printing by automatically advancing the processing to step S 2506  in  FIG. 13  if it is determined that the tray full stack state has been solved. 
     In this case, it is also useful if the control unit  201  executes the processing in step S 2606  and beyond while displaying the screen illustrated in  FIG. 16 ,  FIG. 17 , or  FIG. 12  on the operation unit  203 . With the above-described configuration, the present exemplary embodiment can increase the efficiency in processing a job by resuming the execution of a suspended job if the tray full stack state has been solved even while the user has been executing an operation for entering a curling correction value. 
     Furthermore, if the user has changed the curling correction value while executing the job after the execution of the job is resumed, then the control unit  201  performs control for changing the amount of engagement of the curling correction roller pairs  340  and  341  at a timing before the sheet passes through the curling correction roller pairs  340  and  341 . With the above-described configuration, the present exemplary embodiment can appropriately correct the curling of a sheet even if the user has changed the setting of the amount of engagement of the curling correction roller pairs  340  and  341  while the sheet is currently being conveyed through the curling correction roller pairs  340  and  341 . 
     On the other hand, if it is determined in step S 2601  that no curling of the sheet that may have caused the tray full stack state has occurred (NO in step S 2601 ), then the processing advances to step S 2607 . In step S 2607 , the control unit  201  displays a message to prompt the user to remove the sheet from the large-capacity stacker. 
     In step S 2606 , the control unit  201  determines whether the full-stack on tray has been solved. If it is determined in step S 2606  that the full-stack on tray has been solved (YES in step S 2606 ), then the processing advances to step S 2506  ( FIG. 13 ), which is continued from the processing in step S 2606  in  FIG. 14  (indicated with processing continuation reference numeral “ 2 ” indicated with a circle in  FIGS. 14 and 13 ). 
     As described above with reference to  FIGS. 13 and 14 , the control unit  201  performs control in executing a job. Now, the present exemplary embodiment will be described in detail below with reference to  FIG. 19 . Suppose here that sheets fed from a paper feed cassette A have been discharged on the stack tray  254  of the large-capacity stacker  200   a  and that the control unit  201  has received a tray-full signal from the stack tray  254  when the sheets fed from the paper feed cassette A have been discharged on the stack tray  254 . In this case, the control unit  201  specifies the paper feed unit used in the currently executed job by referring to the job management table illustrated in  FIG. 15  and then displays the screen illustrated in  FIG. 17 . 
     The screen illustrated in  FIG. 17  is displayed when the paper feed cassette A ( FIG. 19 ) is the paper feed cassette  401 . By referring to the information displayed on the screen illustrated in  FIG. 17 , the user can easily recognize the paper feed cassette, of the plurality of paper feed cassettes, which has fed the curled sheet. 
     The image forming apparatus  100  having the above-described configuration according to the present exemplary embodiment performs the following control with the control unit  201  if a tray full stack state has occurred on the stack tray  254  of the large-capacity stacker and the curling of the sheet has caused the tray full stack state. That is, the control unit  201  displays a screen displaying the paper feed unit that is the paper feed source of the sheet in the currently executed job on the operation unit  203 . By referring to the screen, the user can easily recognize the paper feed unit, of the plurality of paper feed units, which has fed the curled sheet. 
     Furthermore, when the user has selected the paper feed cassette whose curling correction amount is to be adjusted via the screen illustrated in  FIG. 17 , the image forming apparatus  100  according to the present exemplary embodiment displays the screen illustrated in  FIG. 12  to allow the user to adjust the curling correction amount for the paper feed unit. Thus, the user is allowed to adjust the curling correction amount by displaying the screen for adjusting the curling correction amount with a simple operation without shifting the screen displayed on the operation unit  203  from the top (default) screen to the screen for correcting the curling of the sheet that displays the paper feed unit. 
     In the present exemplary embodiment, in step S 2605 , the control unit  201  displays the notification screens illustrated in  FIGS. 16 and 17 . However, the present invention is not limited to this. That is, it is also useful if the control unit  201  displays the screen illustrated in  FIG. 18  in step S 2605 . In this case, the time required for the user to adjust the curling correction amount can be reduced. 
     In the present exemplary embodiment, in step S 2505 , the control unit  201  determines whether curling of the sheet has occurred if it is determined that the tray full stack state has occurred on the stack tray  254  of the large-capacity stacker. However, the present invention is not limited to this. That is, it is also useful if the control unit  201  determines whether curling of the sheet discharged on the stack tray  254  has occurred even if the tray full stack state has not occurred. 
     In this regard, it is also useful, for example, if the control unit  201  determines whether curling of the discharged sheet has occurred with the curling detection sensors  701  and  702  every time a sheet is discharged on the stack tray  254 . In this case, the control unit  201  can refer to the job management table to specify the paper feed unit that has fed the curled sheet and notify the curled sheet feeding source paper feed unit to the user. With this configuration, the present exemplary embodiment can allow the user to easily recognize the paper feed unit that has fed the curled sheet even if a tray full stack state has not occurred. 
     Now, a second exemplary embodiment of the present invention will be described in detail below. 
     In the first exemplary embodiment, if a tray full stack state has occurred on the stack tray  254  of the large-capacity stacker and the curling of the sheet has caused the tray full stack state as illustrated in  FIG. 19 , the control unit  201  displays the screen displaying one paper feed cassette that is the paper feed source of the sheet in the currently executed job. In this regard, the number of paper feed sources in the currently executed job may not be limited to one. That is, a plurality of paper feed units may feed sheets in the currently executed job. That is, a plurality of paper feed source units may be used in a job in which the user has instructed to feed sheets from a plurality of paper feed cassettes or in a job in which the paper feed cassette (paper feed source unit) has been switched because the quantity of sheets remaining in the paper feed unit has become small during executing the job. 
     The second exemplary embodiment concerns control executed when the sheets used in the currently executed job has been fed from a plurality of different paper feed sources in the above-described case, for example. 
     Main components of the image forming system  1000  according to the second exemplary embodiment are similar to those of the image forming system  1000  of the first exemplary embodiment. Accordingly, the detailed description thereof will not be repeated here. That is, only units and components different from those of the first exemplary embodiment will be described in detail below. 
       FIG. 20  illustrates a job management table stored on the RAM  206  in the present exemplary embodiment. Referring to  FIG. 20 , in executing a job B, a plurality of paper feed cassettes is used. 
     In specifying the paper feed unit whose curling of the sheet is to be corrected in step S 2604  ( FIG. 14 ), the control unit  201  refers to a job management table illustrated in  FIG. 20  to specify the paper feed unit used in the currently executed job. The job management table illustrated in  FIG. 20  stores information indicating that a plurality of paper feed cassettes (the paper feed cassettes  401  and  404 ) has been used during the currently executed job B. 
     After specifying the paper feed cassette on which the curling correction amount is to be adjusted in step S 2604 , the control unit  201  displays the screen illustrated in  FIG. 16  on the operation unit  203 . When the user presses the curling correction button  3903  via the screen illustrated in  FIG. 16 , the control unit  201  displays a screen illustrated in  FIG. 21  on the operation unit  203 . 
     Paper feed unit buttons  1  through  8  ( FIG. 21 ) correspond to the paper feed cassettes  401  through  408 , respectively. On the screen illustrated in  FIG. 21 , the control unit  201  performs control so that the paper feed unit buttons  1  (a button  4001  in  FIG. 21) and 4  (a button  4002  in  FIG. 21 ) are displayed in a color different from the color of the other paper feed unit buttons to indicate the paper feed units whose curling of the sheet is to be corrected. With this configuration, the present exemplary embodiment can allow the user to easily recognize the paper feed units whose curling of the sheet is to be corrected. 
     When the user presses the setting button  4003  in the state where the paper feed unit button  1  has been selected, the control unit  201  displays a screen illustrated in  FIG. 22  on the operation unit  203 . The user can adjust the curling correction amount via the screen illustrated in  FIG. 22  by operating a button  3705  for the paper feed cassette  401 , which corresponds to paper feed unit button  1 . 
     The screen illustrated in  FIG. 22  includes a “next” button  3704 . By operating the “next” button  3704 , the user can adjust the curling correction amount for a plurality of paper feed cassettes. Furthermore, by pressing the “next” button  3704 , the user can shift the screen to a screen for adjusting the curling correction amount for another paper feed unit. 
     In the present exemplary embodiment, when the user presses the “next” button  3704  via the screen illustrated in  FIG. 22 , a screen for adjusting the curling correction amount for the paper feed cassette  404  is displayed. 
     The processing in step S 2604  and beyond is similar to that described above in the first exemplary embodiment. Accordingly, the detailed description thereof will not be repeated here. 
     In the present exemplary embodiment, the control unit  201  performs the above-described control. Now, the present exemplary embodiment will be described in detail below with reference to  FIG. 23 . 
     Suppose here that sheets fed from a paper feed cassette A have been discharged on the stack tray  254  of the large-capacity stacker  200   a  and then a sheet fed from a paper feed cassette B has been discharged on the same stack tray as illustrated in  FIG. 23 . If the control unit  201  has received a tray-full signal from the stack tray while the sheet is being fed from the paper feed cassette B, then the control unit  201  specifies the paper feed unit used in the currently executed job by referring to the job management table illustrated in  FIG. 19  and then displays the screen illustrated in  FIG. 21 . 
     The screen illustrated in  FIG. 21  is displayed when the paper feed cassette A is the paper feed cassette  401  and the paper feed cassette B is the paper feed cassette  404  or vice versa. By referring to the information displayed on the screen illustrated in  FIG. 21 , the user can easily recognize the specific paper feed cassettes, of the plurality of paper feed cassettes, which have fed the curled sheets. 
     The image forming apparatus  100  having the above-described configuration according to the present exemplary embodiment performs the following control with the control unit  201  if a tray full stack state has occurred on the stack tray  254  of the large-capacity stacker and the curling of the sheet has caused the tray full stack state. That is, the control unit  201  displays a screen displaying a plurality of paper feed units that are the paper feed sources of the sheets in the currently executed job on the operation unit  203 . By referring to the screen, the user can easily recognize the paper feed source unit, of the plurality of paper feed units, that has fed the curled sheet even when a plurality of paper feed units whose curling of the sheet is to be corrected exists. Furthermore, the present exemplary embodiment can allow the user to easily adjust the curling correction amount for the paper feed units that have fed the curled sheets. 
     Furthermore, when the user has selected the paper feed cassette whose curling correction amount is to be adjusted via the screen illustrated in  FIG. 21 , the image forming apparatus  100  according to the present exemplary embodiment displays the screen illustrated in  FIG. 22  to allow the user to adjust the curling correction amount for the paper feed unit. Thus, the user is allowed to adjust the curling correction amount by displaying the screen for adjusting the curling correction amount with a simple operation without shifting the screen displayed on the operation unit  203  from the top (default) screen to the screen for correcting the curling of the sheet that displays the paper feed unit. 
     Now, a third exemplary embodiment of the present invention will be described in detail below. 
     In the second exemplary embodiment, if a tray full stack state has occurred on the stack tray  254  of the large-capacity stacker and the curling of the sheet has caused the tray full stack state as illustrated in  FIG. 23 , the control unit  201  displays the screen displaying a plurality of paper feed cassettes that are the paper feed sources of the sheets in the currently executed job. In this regard, the sheets that have been discharged and stacked on the stack tray  254  may not be limited to those in the currently executed job. That is, sheets discharged in another job that has been completed may be stacked on the same stack tray. The third exemplary embodiment concerns control executed when sheets that have been discharged in another completed job are stacked on the stack tray. 
     Main components of the image forming system  1000  according to the third exemplary embodiment are similar to those of the image forming system  1000  of the second exemplary embodiment. Accordingly, the detailed description thereof will not be repeated here. That is, only units and components different from those of the second exemplary embodiment will be described in detail below. 
       FIG. 24  illustrates a job management table stored on the RAM  206  in the present exemplary embodiment. Referring to  FIG. 24 , a job A has been already completed. The paper discharge destination is the stack tray  254  of the large-capacity stacker  200   a  in the job A. Furthermore, a “removal flag” stored in the job management table illustrated in  FIG. 24  indicates that the sheets discharged by executing the job A have not been removed from the stack tray. 
     When the sheets are removed therefrom, the control unit  201  changes the parameter for the removal flag to “removed”. If it is detected that the sheets on the stack tray have been removed according to a signal from a sheet presence detection sensor (not illustrated) of the large-capacity stacker, then the control unit  201  recognizes that the sheets have been removed. In this case, the control unit  201  changes the parameter for the removal flag from “unremoved” to “removed”. 
     If the parameter “unremoved” has been set for a plurality of removal flags and the sheets are removed in this state, the control unit  201  changes the parameters for all the removal flags from “unremoved” to “removed”. In this regard, it is also useful if the control unit  201  changes the parameters for the removal flag from “unremoved” to “removed” if a signal indicating that the front door of the large-capacity stacker has been opened is received from the door open/closed state sensor of the large-capacity stacker. 
       FIG. 25  is a flow chart illustrating processing executed by the control unit  201  according to the present exemplary embodiment. The processing illustrated in the flow chart in  FIG. 25  is executed by the control unit  201  loading and executing a program from the ROM  205 . 
     Note that the control unit  201  executes the processing illustrated in the flow chart in  FIG. 25  if a tray full stack state has occurred in step S 2505  in  FIG. 13  during processing illustrated in  FIG. 13 . 
     Referring to  FIG. 25 , in step S 2611 , the control unit  201  determines whether curling of the sheet has occurred and the curling of the sheet has caused a tray full stack state according to a signal from the curling detection sensors  701  and  702 . If the curling of the sheet has caused the tray full stack state in step S 2611  (YES in step S 2611 ), then the processing advances to step S 2612 . In step S 2612 , the control unit  201  determines whether any job is currently being being executed. 
     If it is determined that no job is currently being executed in step S 2612  (NO in step S 2612 ), then the processing advances to step S 2613 . In step S 2613 , the control unit  201  specifies (identifies) the paper feed cassette used in the completed job. In step S 2614 , the control unit  201  displays a message on the operation unit  203  indicating that the stack tray  254  is in a tray full stack state (i.e., that the stack tray  254  is full of or almost full of sheets stacked thereon) At the same time, the control unit  201  displays the screen illustrated in  FIG. 16  on the operation unit  203 . 
     When the user presses the button  3903  on the screen illustrated in  FIG. 16 , the control unit  201  displays a screen on the operation unit  203  that displays the paper feed unit button corresponding to the paper feed cassette specified in step S 2614  in a color different from the colors of the other paper feed unit buttons. 
     On the other hand, if a job is currently being executed in step S 2612  (YES in step S 2612 ), then the processing advances to step S 2615 . In step S 2615 , the control unit  201  performs control illustrated in  FIG. 26 .  FIG. 26  illustrates exemplary control according to the present exemplary embodiment. 
     Referring to  FIG. 26 , in step S 2621 , the control unit  201  determines whether any completed job whose removal flag has the parameter “unremoved” exists. If a completed job whose removal flag has the parameter “unremoved” exists (YES in step S 2621 ), then the processing advances to step S 2622 . In step S 2622 , the control unit  201  refers to the job management table illustrated in  FIG. 24  to specify (identify) the paper feed cassette used in the completed job and the currently executed job. Then, the processing advances to step S 2616  in  FIG. 25 . 
     In step S 2616 , the control unit  201  changes the color of the paper feed unit button corresponding to the paper feed cassette specified in step S 2622  and displays the button on the operation unit  203 . In this regard,  FIG. 27  illustrates an example of the screen displayed on the operation unit  203  in step S 2616 . 
     On the other hand, if no completed job exists in step S 2621  (NO in step S 2621 ), then the processing advances to step S 2623 . In step S 2623 , the control unit  201  refers to the job management table to specify (identify) the paper feed cassette used in the currently executed job. Then, the processing advances to step S 2616  in  FIG. 25 . 
     The processing performed in step S 2616  and beyond is similar to that of the second exemplary embodiment. For example, steps S 2606  and S 2607  of  FIG. 14  correspond to steps S 2617  and S 2618  of  FIG. 25 , respectively. Accordingly, the detailed description thereof will not be repeated here. 
     The image forming apparatus  100  having the above-described configuration according to the present exemplary embodiment performs the following control with the control unit  201  if a tray full stack state has occurred on the stack tray  254  of the large-capacity stacker  200   a  and the curling of the sheet has caused the tray full stack state. 
     That is, the control unit  201  determines whether any completed job whose sheets discharged on the stack tray  254  of the large-capacity stacker have not been removed from the stack tray  254  exists. If a completed job satisfying the above-described condition exists, the control unit  201  specifies the paper feed cassette used in the completed job as well as the paper feed cassette used in the currently executed job. Furthermore, the control unit  201  displays the specified paper feed cassette on the operation unit  203  as the paper feed cassette whose curling correction amount is to be adjusted. With the above-described configuration, the present exemplary embodiment can allow the user to easily recognize the paper feed cassette whose curling of the sheet is to be corrected with respect to the completed job as well as the currently executed job. 
     Suppose here that in a completed job, sheets fed from a paper feed cassette A have been discharged on the stack tray  254  of the large-capacity stacker  200   b  and then sheets fed from a paper feed cassette B have been discharged on the same stack tray as illustrated in  FIG. 28 . If the control unit  201  has received a tray-full signal from the stack tray while the sheet is being fed from a paper feed cassette D after discharging sheets from a paper feed cassette C, then the control unit  201  specifies the paper feed unit used in the currently executed job by referring to the job management table illustrated in  FIG. 24  and then displays the screen illustrated in  FIG. 27 . 
     The screen as illustrated in  FIG. 27  is displayed when the paper feed cassette A ( FIG. 28 ) is the paper feed cassette  401 , the paper feed cassette B ( FIG. 28 ) is the paper feed cassette  404 , the paper feed cassette C ( FIG. 28 ) is the paper feed cassette  403 , and the paper feed cassette D ( FIG. 28 ) is the paper feed cassette  405 . 
     The image forming apparatus  100  according to the present exemplary embodiment allows the user to adjust the curling correction amount for the paper feed cassette by selecting the paper feed cassette and pressing a setting button  4102  via the screen illustrated in  FIG. 27 . Thus, the user is allowed to adjust the curling correction amount by displaying the screen for adjusting the curling correction amount with a simple operation without shifting the screen displayed on the operation unit  203  from the top (default) screen to the screen for correcting the curling of the sheet that displays the paper feed unit. 
     Now, a fourth exemplary embodiment of the present invention will be described in detail below. 
     In the above-described third exemplary embodiment, if a tray full stack state has occurred on the stack tray  254  of the large-capacity stacker and the curling of the sheet has caused the tray full stack state as illustrated in  FIG. 28 , the control unit  201  displays the screen displaying a plurality of paper feed cassettes that are the paper feed sources of sheets in the completed job and the currently executed job. The present exemplary embodiment concerns processing for determining the priority of level of curling correction and notifies the result of the determination to the user if a plurality of paper feed units whose curling of the sheet is to be corrected exists. In the present exemplary embodiment, the priority is determined by the control unit  201  according to the descending numeric order of the number of sheets fed from the paper feed unit. 
       FIG. 29  illustrates a job management table stored on the RAM  206  according to the present exemplary embodiment. Referring to  FIG. 29 , a job A is the completed job whose paper discharge destination is the stack tray  254  of the large-capacity stacker  200   a.  Furthermore, a “removal flag” stored in the job management table illustrated in  FIG. 29  indicates that the sheets discharged by executing the job A have not been removed from the stack tray. 
     The method for managing the “removal flag” is the same as that in the third exemplary embodiment. Accordingly, the detailed description thereof will not be repeated here. The job management table illustrated in  FIG. 29  stores information about the number of sheets that have been fed with respect to each paper feed cassette used in the job. The control unit  201  stores, in the job management table illustrated in  FIG. 29 , a count value about the number of sheets that have been fed from each paper feed unit by using a counter (not illustrated) according to a signal from a sensor provided at a paper feed port of each paper feed unit. 
     Main components of and control executed by the image forming system  1000  according to the fourth exemplary embodiment are similar to those in the third exemplary embodiment. Accordingly, the detailed description thereof will not be repeated here. Hereinbelow, only the configuration different from that of the third exemplary embodiment will be described in detail. 
     The control unit  201  reads the number of sheets fed from each paper feed unit specified in step S 2615  (in  FIG. 25 ) and compares the read the numbers of sheets. In step S 2616 , the control unit  201  determines the priority in the descending numeric order of the number of sheets according to the comparison result. As illustrated in the job management table ( FIG. 29 ), the number of fed sheets is greater in the order of the paper feed cassette  405 , the paper feed cassette  403 , the paper feed cassette  401 , and the paper feed cassette  404 , which are used in the job. Accordingly, in step S 2616 , the control unit  201  displays a screen illustrated in  FIG. 30 . 
     The processing in step S 2616  and beyond is similar to that in the third exemplary embodiment. Accordingly, the detailed description thereof will not be repeated here. 
     The image forming apparatus  100  having the above-described configuration according to the present exemplary embodiment performs the following control with the control unit  201  if a tray full stack state has occurred on the stack tray  254  of the large-capacity stacker  200   a  and the curling of the sheet has caused the tray full stack state. 
     That is, the control unit  201  determines whether any completed job whose sheets discharged on the stack tray  254  of the large-capacity stacker have not been removed from the stack tray  254  exists. If a completed job satisfying the above-described condition exists, the control unit  201  specifies the paper feed cassette used in the completed job as well as the paper feed cassette used in the currently executed job. Furthermore, the control unit  201  displays, on the operation unit  203 , the screen displaying the plurality of paper feed units that are the sheet feeding source units in the currently executed job and the completed job in the priority of descending numeric order of the number of sheets fed from the paper feed unit whose curling of the sheet is to be corrected. Thus, the present exemplary embodiment can allow the user to easily recognize the paper feed units that are the sources of feeding the sheet whose curling is to be corrected in the descending order of the sheets that have been fed therefrom. 
     In this regard, suppose here, for example, as illustrated in  FIG. 31 , that after discharging N sheets (N is an integer of 1 or greater) fed from a paper feed cassette A on the stack tray  254  of the large-capacity stacker  200   a,  M sheets (M is an integer of 1 or greater) fed from a paper feed cassette B have been discharged and stacked on the same stack tray. If the control unit  201  has received a tray-full signal from the stack tray in this state while I sheets (I is an integer of 1 or greater) are being fed from a paper feed cassette D after feeding K sheets (K is an integer of 1 or greater) from a paper feed cassette C, then the control unit  201  specifies the paper feed units used in the completed job and the currently executed job by referring to the job management table illustrated in  FIG. 29 . Furthermore, the control unit  201  compares the number of sheets fed from each of the paper feed cassettes according to the job management table illustrated in  FIG. 29 . Then, the control unit  201  displays the screen illustrated in  FIG. 30 . 
     Here, in the screen illustrated in  FIG. 30 , the paper feed cassettes are provided with specific ascending numbers starting from “1” in the descending numeric order of the number of sheets fed therefrom. The screen illustrated in  FIG. 30  is displayed when the paper feed cassette A is the paper feed cassette  401 , the paper feed cassette B is the paper feed cassette  404 , the paper feed cassette C is the paper feed cassette  403 , and the paper feed cassette D is the paper feed cassette  405 . 
     Furthermore, if it is detected that the user has pressed a setting button  4302  via the screen illustrated in  FIG. 30  in a state where the paper feed unit buttons  1 ,  3 ,  4 , and  5  are selected, then the control unit  201  displays the screen illustrated in  FIG. 22  on the operation unit  203 . When the user presses the “next” button  3704 , the control unit  201  shifts the screens in the order illustrated in  FIG. 32  according to the priority (descending numeric order of the number of sheets fed from the paper feed units). 
     With the above-described configuration, the present exemplary embodiment can allow the user to recognize the paper feed cassettes whose curling of the sheet is to be corrected in the descending numeric order of the number of sheets fed therefrom. In addition, according to the present exemplary embodiment, the user can adjust the curling correction amount for the paper feed units whose curling of the sheet is to be corrected according to the priority determined in the above-described manner. 
     In the above-described embodiments, the image forming apparatus  100  is connected to the paper feed deck  50  and the control unit  201  displays the paper feed units whose curling of the sheet is to be corrected, which have been specified from among the plurality of paper feed units of the image forming apparatus  100  and the paper feed deck  50 , on the operation unit  203 . However, the present invention is not limited to this. That is, the paper feed deck  50  is not always necessary. In this regard, if no paper feed deck  50  is provided (if no paper feed deck  50  is connected to the image forming apparatus  100 ), then it is useful if the control unit  201  displays the paper feed cassette whose curling of the sheet is to be corrected on the operation unit  203 , which has been specified from among a plurality of paper feed cassettes of the image forming apparatus  100 . 
     Furthermore, the number of paper feed cassettes of the image forming apparatus  100  and the paper feed deck  50  is not limited to the above-described number. That is, it is also useful if a greater number of paper feed cassettes are provided. Furthermore, it is also useful if the paper feed unit is not a paper feed cassette but a paper feed unit of any other appropriate type. 
     In the present exemplary embodiment, two paper feed decks  50  (the paper feed decks  50   a  and  50   b ) are connected to the image forming apparatus  100 . However, the present invention is not limited to this. That is, 0 through n (n is a natural number) paper feed decks  50  can be arbitrarily provided and connected to the image forming apparatus  100 . Furthermore, The number of large-capacity stackers is not limited to two. That is, 1 through n (n is an integer of 2 or greater) large-capacity stackers can be used. 
     Furthermore, in the above-described embodiments, the control unit  201  detects the tray full stack state or the occurrence of curling of the sheet, if any, with respect to the sheets stacked on the stack tray  254  of the large-capacity stacker  200   a.  The control unit  201  notifies the paper feed unit whose curling of the sheet is to be corrected. However, the above-described control can be performed on the sheets stacked on the stack tray  254  of the large-capacity stacker  200   b  or on a paper discharge tray such as the output tray  282  of the saddle stitch binding machine  200   c.    
     Furthermore, when the tray full stack state has occurred on the stack tray  254  of one large-capacity stacker but the stack tray of another large-capacity stacker can stack the sheet, it is also useful if the control unit  201  performs control for discharging the sheet on the stack tray of the another large-capacity stacker. With this configuration, the present exemplary embodiment can prevent suspension of a currently executed job due to the occurrence of a tray full stack state. 
     In addition, in the above-described embodiments, various display screens (i.e., the screens illustrated in  FIGS. 10 through 12  and  FIGS. 16 through 18 , for example) are displayed on the operation unit  203  to notify information to the user. However, the notification method is not limited to the method for displaying the button for the specified paper feed unit in a color different from the color of the buttons for the other paper feed units. That is, any method capable of specifying the paper feed unit that has fed the curled sheet can be used. 
     In addition, the notification to the user can be performed by transmitting information to an external computer (a client computer or a server computer) connected to the image forming apparatus  100  via the external I/F unit  209  and displaying a screen similar to the above-described screen on a display of the external computer. Furthermore, the notification can be performed by a method other than displaying information. That is, it is also useful if the image forming apparatus  100  or an external computer having an audio output unit notifies information to the user by audio information output from the audio output unit. 
     Furthermore, in the above-described embodiments, an image forming apparatus that forms an image by electrophotographic processing is described as an example of the sheet conveyance apparatus. However, the present invention is not limited to this. That is, the present exemplary embodiment can be implemented on an image forming apparatus that forms an image by an inkjet image forming method. In addition, the present exemplary embodiment can be implemented on an apparatus that does not form an image but corrects the curling of a sheet to be conveyed therethrough. 
     Moreover, in the above-described embodiments, the user enters a curling correction value for a specific paper feed unit to correct the curling of the sheet. However, various other methods, such as changing the sheet or the image forming condition can be used to address curling of the sheet. 
     As described above, embodiments of the present invention specify the paper feed unit (s) that has fed the curled sheet and notify the specified paper feed unit(s) to the user. Accordingly, the present exemplary embodiment can allow the user to perform correction of the curling of the sheet separately and independently for each paper feed unit. 
     Accordingly, the present exemplary embodiment can prevent the degradation of the quality of a resulting processed product. In addition, the present exemplary embodiment can prevent the reduction of the maximum stackable number of sheets on the stack tray due to the curling of the sheet. Furthermore, the present exemplary embodiment can prevent the deterioration of the stability of the sheet bundle stacked on the stack tray, which may otherwise occur due to the curling of the sheet. 
     Hereinbelow, the configuration of a data processing program that can be read by a sheet processing apparatus according to an exemplary embodiment of the present invention will be described in detail with reference to memory maps illustrated in  FIG. 33 . 
       FIG. 33  illustrates a memory map of a computer-readable storage medium that stores various data processing programs that can be read by a sheet processing apparatus according to an exemplary embodiment of the present invention. 
     Although not illustrated in  FIG. 33 , information for managing the programs stored in the computer-readable storage medium such as version information and information concerning the creator of a program, for example, can be stored in the computer-readable storage medium. In addition, information that depends on an operating system (OS) of an apparatus that reads the program, such as an icon for specifying and displaying the program, can be stored in the computer-readable storage medium. 
     In addition, data that is subordinate to the various programs is also managed in a directory of the computer-readable storage medium. In addition, a program for installing the various programs on a computer can be stored in the computer-readable storage medium. In addition, in the case where a program to be installed is compressed, a program for decompressing the compressed program can be stored in the computer-readable storage medium. 
     In addition, the functions according to the above-described exemplary embodiments can be implemented by a host computer using a program that is externally installed. In this case, the present invention is applied to the case where a group of information including a program is supplied to an output device from a computer-readable storage medium such as a compact disc-read only memory (CD-ROM), a flash memory, and a floppy disk (FD) or from an external computer-readable storage medium through a network. 
     The present invention can also be achieved by providing a system or an apparatus with a computer-readable storage medium storing program code of software implementing the functions of the embodiments and by reading and executing the program code stored in the computer-readable storage medium with a computer of the system or the apparatus (a central processing unit (CPU) or a micro processing unit (MPU)). 
     In this case, the program code itself, which is read from the computer-readable storage medium, implements the functions of the embodiments described above, and accordingly, the computer-readable storage medium storing the program code constitutes the present invention. Accordingly, the program can be configured in any form, such as object code, a program executed by an interpreter, and script data supplied to an OS. 
     As the computer-readable storage medium for supplying such program code, a floppy disk, a hard disk, an optical disk, a magneto-optical disk, a magnetooptic disk (MO), a CD-ROM, a compact disc recordable (CD-R), a compact disc rewritable (CD-RW), a magnetic tape, a nonvolatile memory card, a read only memory (ROM), and a digital versatile disc (DVD (DVD-recordable (DVD-R), DVD-rewritable (DVD-RW))), for example, can be used. 
     In this case, the program code itself, which is read from the computer-readable storage medium, implements the function of the embodiments mentioned above, and accordingly, the computer-readable storage medium storing the program code constitutes the present invention. 
     The above program can also be supplied by connecting to a web site on the Internet by using a browser of a client computer and by downloading the program from the web site to a computer-readable storage medium such as a hard disk. In addition, the above program can also be supplied by downloading a compressed file that includes an automatic installation function from the web site to a computer-readable storage medium such as a hard disk. The functions of the above embodiments can also be implemented by dividing the program code into a plurality of files and downloading each divided file from different web sites. That is, a World Wide Web (WWW) server and a file transfer protocol (ftp) server for allowing a plurality of users to download the program file for implementing the functional processing configure the present invention. 
     In addition, the above program can also be supplied by distributing a computer-readable storage medium such as a CD-ROM and the like which stores the program according to the present invention after an encryption thereof, by allowing the user who is qualified for a prescribed condition to download key information for decoding the encryption from the web site via the Internet, and by executing and installing in the computer the encrypted program code by using the key information. 
     In addition, the functions according to the embodiments described above can be implemented not only by executing the program code read by the computer, but also implemented by the processing in which an OS or the like carries out a part of or the whole of the actual processing based on an instruction given by the program code. 
     Further, in another aspect of the embodiment of the present invention, after the program code read from the computer-readable storage medium is written in a memory provided in a function expansion board inserted in a computer or a function expansion unit connected to the computer, a CPU and the like provided in the function expansion board or the function expansion unit carries out a part of or the whole of the processing to implement the functions of the embodiments described above. 
     In the above-described embodiments of the present invention, the control unit  201  of the image forming apparatus  100  primarily performs the above-described various control operations. However, a part of or the entire various control operations can be performed by an external controller provided in an apparatus or a device other than the image forming apparatus  100 . 
     While the present invention has been described with reference to exemplary embodiments 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 modifications, equivalent structures, and functions. 
     This application claims priority from Japanese Patent Application No. 2008-050127 filed Feb. 29, 2008, which is hereby incorporated by reference herein in its entirety.