Patent Publication Number: US-2022227150-A1

Title: Print control apparatus, control method therefor, storage medium storing control program therefor, and print system

Description:
BACKGROUND OF THE INVENTION 
     Field of the Invention 
     The present invention relates to a print control apparatus, a control method therefor, a storage medium storing a control program therefor, and a print system. 
     Description of the Related Art 
     Production printing employs an image forming apparatus that can treat various types of sheets, such as thin paper, thick paper, coated paper, and a film. Such an image forming apparatus is provided with a sheet feed unit that consists of a plurality of sheet feed cassettes. Different types of sheets are respectively stored in the different sheet feed cassettes. Sheet information about stored sheets is set to each of the sheet feed cassettes. The sheet information includes attributes, such as a name, a size, and basis weight, of a sheet and adjustment values, such as an adjustment value of a secondary transfer voltage and an adjustment value of an image position, that are optimized for each sheet type. 
     Since an image forming apparatus used for production printing has many adjustable items, it takes time and effort to set desired adjustment items to optimum values. For example, a user specifies an adjustment item that should be adjusted on the basis of a symptom of an image defect that is appeared in printed matter. Since the user is required to repeat adjustment and test print until the symptom is canceled, a user&#39;s workload is extremely large. Japanese Laid-Open Patent Publication (Kokai) No. 2020-118931 (JP 2020-118931A) and Japanese Laid-Open Patent Publication (Kokai) No. 2013-37185 (JP 2013-37185A) propose techniques that reduce a user&#39;s workload in an image forming apparatus of an electrophotographic system that forms an image by transferring a toner image onto a sheet while applying voltage to a transfer member. 
     JP 2020-118931A discloses the technique that forms a plurality of patch images while gradually changing a secondary transfer voltage applied to the transfer member and that sets the optimal secondary transfer voltage by a user by checking transfer properties of these patch images. Although the technique can reduce the user&#39;s workload because the repeat of the adjustment and test print becomes unnecessary, the time and effort of a user to visually check a plurality of printed patch images remain. 
     As compared with this, JP 2013-37185A discloses the technique that automatically sets the optimal secondary transfer voltage by detecting a plurality of patch images formed on a sheet with a density sensor. When this technique is used, not only the repeat of the adjustment and test print becomes unnecessary, but also the visual check of the patch images by a user becomes unnecessary. As a result, a user&#39;s workload can be further reduced. 
     However, the method that detects the patch images with the density sensor may not set the optimal secondary transfer voltage that a user desires. In such a case, the user is required to readjust the secondary transfer voltage by visually checking the patch images. Moreover, since this conventional technique respectively requires a plurality of operations in a case of displaying information about an adjustment value of the secondary transfer voltage to determine necessity of the readjustment of the secondary transfer voltage and in a case of displaying a setting screen for readjusting the secondary transfer voltage, the operability is extremely bad. 
     SUMMARY OF THE INVENTION 
     The present invention provides a mechanism that improves operability in readjusting a secondary transfer voltage that has been adjusted. 
     Accordingly, an aspect of the present invention provides a print control apparatus that communicates with an image forming apparatus. The print control apparatus includes an instruction unit configured to instruct the image forming apparatus to execute a process that prints a predetermined chart, reads the predetermined chart by the reading device, and sets a secondary transfer voltage, a reception unit configured to receive an adjustment value obtained by the process from the image forming apparatus, and a display control unit configured to control a display unit to display an object that prompts a user to adjust at least the secondary transfer voltage based on reception of the adjustment value obtained by the process by the reception unit. 
     According to the present invention, the operability in readjusting the secondary transfer voltage that has been adjusted is improvable. 
     Further features of the present invention will become apparent from the following description of exemplary embodiments with reference to the attached drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a configuration diagram schematically showing a configuration of a print system equipped with a print control apparatus according to an embodiment of the present invention. 
         FIG. 2  is a side view of an image forming apparatus in  FIG. 1 . 
         FIG. 3  is a block diagram schematically showing a configuration of the image forming apparatus in  FIG. 1 . 
         FIG. 4A  and  FIG. 4B  are block diagrams describing a configuration of the print control apparatus in  FIG. 1 . 
         FIG. 5  is a view showing an example of a top screen displayed on an external display device of the print control apparatus in  FIG. 1 . 
         FIG. 6  is a flowchart showing procedures of a top-screen-display control process executed by the print control apparatus in  FIG. 1 . 
         FIG. 7  is a flowchart showing procedures of an initialization process executed by the image forming apparatus in  FIG. 1 . 
         FIG. 8  is a view showing an example of the sheet setting management table managed by a sheet management application in  FIG. 4B . 
         FIG. 9  is a view showing an example of a sheet-feed-cassette screen displayed on an external display device in selecting a sheet feed cassette button on the top screen in  FIG. 5 . 
         FIG. 10A  and  FIG. 10B  are views showing examples of charts printed with a print engine in  FIG. 2 . 
         FIG. 11  is a graph showing an example of a result that a reading device in  FIG. 1  reads. 
         FIG. 12  is a flowchart showing procedures of a secondary-transfer-voltage adjustment process executed by the print system in  FIG. 1 . 
         FIG. 13A ,  FIG. 13B ,  FIG. 13C , and  FIG. 13D  are views showing examples of screens displayed on an external display device in  FIG. 4A . 
         FIG. 14A  and  FIG. 14B  are views showing examples of charts printed on sheets in the embodiment. 
         FIG. 15  is a flowchart showing procedures of a modified example of the secondary-transfer-voltage adjustment process executed by the print system in  FIG. 1 . 
         FIG. 16  is a view showing an example of a manual adjustment screen displayed on the external display device in  FIG. 4A . 
     
    
    
     DESCRIPTION OF THE EMBODIMENTS 
     Hereafter, embodiments according to the present invention will be described in detail by referring to the drawings. 
       FIG. 1  is a configuration diagram schematically showing a configuration of a print system  100  equipped with a print control apparatus  102  according to an embodiment of the present invention. 
     As shown in  FIG. 1 , the print system  100  is provided with the print control apparatus  102  and an image forming apparatus  103 . The print control apparatus  102  is connected with the image forming apparatus  103  through an image video cable  107  and a control cable  108 . Moreover, the print control apparatus  102  is connected to a LAN (Local Area Network)  110  through an Ethernet cable  109  and communicates with a client computer  101  through the LAN  110 . The image forming apparatus  103  is not connected to the LAN  110  but communicates with the client computer  101  through the print control apparatus  102 . Although the configuration in which the image forming apparatus  103  is not connected to the LAN  110  is described in the embodiment, the present invention is not restricted to this configuration. For example, the image forming apparatus  103  may be connected to the LAN  110  and communicate with the client computer  101  through the LAN  110 . 
     The client computer  101  issues a print designation etc. to the print system  100  by starting an application installed in the client computer  101 . The print control apparatus  102  is provided with a controller  400  and a display unit  111 . The print control apparatus  102  cooperates with the image forming apparatus  103  to perform an image process. A user selects and switches information currently displayed on the display unit  111  by operating hardware operation buttons  112  of the print control apparatus  102 . Since the display area of the display module  111  is relatively narrow, the display module  111  displays minimum necessary information, such as information for operating ON/OFF of the power of the print control apparatus  102  and an IP address of the print control apparatus  102 . Moreover, an external display device  113 , a keyboard  114 , and a pointing device  115  are connected to the print control apparatus  102 . It should be noted that the external display device  113  may be provided with a touch position detection function like a touchpad to additionally hold the function of the pointing device  115  in the embodiment. Moreover, the print control apparatus  102  designates execution of automatic adjustment of a secondary transfer voltage mentioned later to the image forming apparatus  103  according to an instruction received from a user. 
     The image forming apparatus  103  is a multifunction apparatus having a plurality of functions and is provided with a scanner unit  104 , an operation panel  105 , a discharge tray  106   a , a discharge tray  106   b , a sheet feed unit  116 , and a reading device  117 . The image forming apparatus  103  not only performs image processing of data received from the client computer  101  or the print control apparatus  102 , but also copies data read by the scanner unit  104  and transmits the data concerned to a shared folder. A user operates the operation panel  105  to designate the scanner unit  104  to read a document, for example. Various kinds of information, such as a scanning state, are displayed on the operation panel  105 . A sheet to which an image has been formed is discharged to the discharge tray  106   a  or the discharge tray  106   b . The sheet feed unit  116  consists of a plurality of sheet feed cassettes that store sheets used to print. Sheets that are different in size and type are respectively stored in the different sheet feed cassettes. When receiving a print instruction, the image forming apparatus  103  selects one sheet feed cassette from among the plurality of sheet feed cassettes, feeds a sheet from the selected sheet feed cassette, and prints an image on the sheet concerned. It should be noted that the number of the sheet feed cassettes that constitute the sheet feed unit  116  depends on an option configuration of the image forming apparatus  103 . Moreover, the configuration of the sheet feed unit  116  is not restricted to the above-mentioned configuration but may also include other mechanisms, such as an inserter and a manual feed tray. The reading device  117  is provided with a sensor that reads a chart printed for various adjustments, such as adjustment of a position of a printed image on a sheet, correction of density unevenness, and adjustment of a secondary transfer voltage. 
       FIG. 2  is a side view of the image forming apparatus  103  in  FIG. 1 . It should be noted that  FIG. 2  shows an internal configuration in a transparent state in order to understand easily and omits a part of the sheet feed unit  116 . 
     As shown in  FIG. 2 , the print engine  210  is provided with the sheet feed unit  116 , development stations  203 ,  204 ,  205 , and  206 , an intermediate transfer belt  207 , a secondary transfer roller  208 , a first fixing unit  211 , and a second fixing unit  213 . In the sheet feed unit  116 , an uppermost sheet of a sheet bundle stored in the selected sheet feed cassette is separated from the sheet bundle and is conveyed to a sheet conveyance path  202 . The development stations  203  through  206  respectively form toner images using the color toners of Y (yellow), M (magenta), C (cyan), and K (black). The formed toner images are first primarily transferred to the intermediate transfer belt  207  so as to overlap to form a full color toner image. The intermediate transfer belt  207  rotates clockwise in  FIG. 2 , and the full color toner image is transferred to the sheet conveyed from the sheet conveyance path  202  with the secondary transfer roller  208 . The sheet to which the toner image is transferred is conveyed to the first fixing unit  211 . 
     The first fixing unit  211  is provided with a pressure roller and a heating roller and fixes the toner image to the sheet by melting and press-fitting the toner while passing the sheet between the rollers. The sheet that passed the first fixing unit  211  passes along the sheet conveyance path  212  and is conveyed to a sheet conveyance path  215 . In the meantime, when a sheet type of a used sheet needs additional melting and press-fitting for fixing, the sheet that has passed the first fixing unit  211  is conveyed to the second fixing unit  213  through a sheet conveyance path  214 . The sheet to which the additional melting and press-fitting are applied with the second fixing unit  213  is conveyed to the sheet conveyance path  215 . When a print mode is set to both-sided printing, the print engine  210  conveys the sheet that has passed the first fixing unit  211  or the second fixing unit  213  to a sheet inversion path  216  to invert the surfaces of the sheet concerned. After that, this sheet is conveyed to the secondary transfer roller  208  through a both-sided conveyance path  217 . At the secondary transfer roller  208 , a toner image is transferred to the surface that is different from the surface to which the toner image has been already transferred of the conveyed sheet. For example, the toner image is transferred to the back surface. 
     The sheet conveyed from the print engine  210  is conveyed to the reading device  117 . In the reading device  117 , a first CIS (Contact Image Sensor)  221  and second CIS  222  are arranged at an upper position and a lower position, respectively. Although the CISs are employed in the embodiment, sensors are not limited to CISs. Other sensors may be employed as long as the sensors are able to read a patch and a marker on a sheet. The first CIS  221  reads an upper side of a sheet and the second CIS  222  reads a lower side of a sheet. The reading device  117  reads patches on a sheet using the first CIS  221  and second CIS  222  at timing at which the sheet conveyed to the sheet conveyance path  223  arrives at the predetermined position. Moreover, the reading device  117  feeds back the read result as image position information, density information, etc. to the print engine  210 . The sheet read with the first CIS  221  and second CIS  222  is conveyed to a finisher  231 . 
     The finisher  231  performs finishing processes, such as a staple process, a punch process, and a saddle stitch bookbinding process, to the sheet conveyed from the reading device  117 . The finisher  231  is provided with a discharge tray  106   a  and a discharge tray  106   b . The finisher  231  discharges a sheet to which the finishing process is applied to the discharge tray  106   a  through a sheet conveyance path  232  or discharges a sheet to the discharge tray  106   b  through a sheet conveyance path  233 . 
       FIG. 3  is a block diagram schematically showing a configuration of the image forming apparatus  103  in  FIG. 1  having a controller  300 . As shown in  FIG. 3 , the controller  300  is provided with a CPU  301 , a RAM  302 , a ROM  303 , an operation-panel I/F  305 , a LAN controller  306 , a print I/F  307 , a disk controller  308 , and a nonvolatile memory  309 . Moreover, the controller  300  is provided with an external storage unit  311 , a scanner I/F  312 , a video I/F  314 , and a reading-device I/F  315 . These are mutually connected through a system bus  304 . 
     The CPU  301  develops control programs stored in the ROM  303  and external storage unit  311  onto the RAM  302 , runs the developed programs, and totally controls components connected to the system bus  304 . For example, the CPU  301  outputs an image signal to the print engine  210  connected through the print I/F  307  and receives an image signal from the scanner unit  104  connected through the scanner I/F  312 . Moreover, the CPU  301  controls the sheet feed unit  116  connected to the print engine  210  through the print I/F  307  and obtains a state of the sheet feed unit  116 . Furthermore, the CPU  301  communicates with the print control apparatus  102  through the LAN controller  306  and control cable  108 . The RAM  302  functions as a main memory, a work area, etc. of the CPU  301 . The external storage unit  311  is an HDD, an IC card, etc. The disk controller  308  controls access to the external storage unit  311 . The external storage unit  311  stores application programs, font data, form data, etc. Moreover, the external storage unit  311  is used as a job storage area that spools a print job temporarily and enables control of the spooled job from the outside. Furthermore, the external storage unit  311  is used as a BOX data storage area that holds image data obtained from the scanner unit  104  and image data of a print job as BOX data. The image data held as the BOX data can be referred from the network and can be printed. Moreover, the external storage unit  311  holds various logs, such as a job log and an image log. 
     The operation panel  105  is connected to the controller  300  through the operation panel I/F  305 . A user is able to input various information by operating software keys displayed on the operation panel  105  and hardware keys arranged on the operation panel  105 . The nonvolatile memory  309  stores information about various settings set up from the operation panel  105  or an external apparatus. The video I/F  314  receives image data from the print control apparatus  102 . The reading-device I/F  315  obtains information about a patch that the reading device  117  reads and density information from the reading device  117 . 
     The reading device  117  is provided with a communication I/F  321 , a CPU  322 , a ROM  323 , a RAM  324 , and an image pickup unit  325 . These components are mutually connected through a system bus  326 . The reading device  117  transmits reading control of a patch and a marker, a read patch, and density information to the controller  300 . 
       FIG. 4A  and  FIG. 4B  are block diagrams describing a configuration of the print control apparatus  102  in  FIG. 1 .  FIG. 4A  is a block diagram schematically showing a configuration of the print control apparatus  102  having a controller  400 . As shown in  FIG. 4A , the controller  400  is provided with a CPU  401 , a RAM  402 , a ROM  403 , an operation I/F  405 , a LAN controller  406 , a LAN controller  407 , a disk controller  408 , and an external storage unit  409 . Moreover, the controller  400  is provided with a video I/F  410 , a keyboard controller  411 , and a display controller  412 . These are mutually connected through a system bus  404 . 
     The CPU  401  develops control programs stored in the ROM  403  and external storage unit  409  onto the RAM  402 , runs the developed programs, and totally controls components connected to the system bus  404 . Moreover, the CPU  401  communicates with the image forming apparatus  103  through the LAN controller  406  and control cable  108 . Furthermore, the CPU  401  communicates with the client computer  101  etc. on the network through the LAN controller  407  and LAN  110 . The RAM  402  functions as a main memory, a work area, etc. of the CPU  401 . The external storage unit  409  is a nonvolatile storage device, such as an HDD, an IC card, or the like. The disk controller  408  controls access to the external storage unit  409 . 
     The external storage unit  409  stores application programs, font data, form data, etc. Moreover, the external storage unit  409  is used as a job storage that spools a print job temporarily and stores a print job that is obtained by applying a RIP (Raster Image Processor) process to the spooled job. The operation I/F  405  exchanges data with the operation buttons  112  and display unit  111 . The video I/F  410  transmits image data to which the RIP process is applied, to the image forming apparatus  103 . The keyboard controller  411  exchanges data with the keyboard  114  and pointing device  115 . The display controller  412  is provided with a video memory, draws image data to the video memory according to an instruction received from the CPU  401 , and outputs the image data drawn in the video memory to the external display device  113  as a video signal. 
       FIG. 4B  is a block diagram schematically showing a configuration of a software module  451  that controls the print control apparatus  102 . As shown in  FIG. 4B , the software module  451  includes a UI control module  452 , a sheet management application  453 , sheet-feed-cassette management module  454 , network control module  455 , job management module  456 , and setting management module  457 . The processes by these modules are achieved because the CPU  401  runs programs that are developed to the RAM  402 . 
     The UI control module  452  controls displays of the display unit  111  and the external display device  113 . The UI control module  452  can switch a text and a display unit system of a sheet size that are displayed on a screen according to a setting of the system. The sheet management application  453  obtains the sheet information about the sheets stored in the sheet feed unit  116  from the image forming apparatus  103  and manages the sheet information with a sheet setting management table  800  shown in  FIG. 8  mentioned later. The sheet information includes attributes, such as a name, a size, and basis weight, of a sheet and adjustment values, such as an adjustment value of a secondary transfer voltage and an adjustment value of an image position, that are optimized for each sheet type. The sheet-feed-cassette management module  454  obtains the sheet-feed-cassette information that shows the configuration of the sheet feed unit  116  from the image forming apparatus  103  and manages the obtained sheet-feed-cassette information. 
     The network control module  455  controls communication with the image forming apparatus  103  through the LAN controller  406  and communication with the client computer  101  on the network through the LAN controller  407 . The job management module  456  manages an execution order of print process sequences and jobs. The job management module  456  manages a job received by the print control apparatus  102  and controls data transfer for printing the received job. For example, the job management module  456  controls so as to transfer the received job to the image forming apparatus  103  through the LAN controller  406  or the video interface  410 . The setting management module  457  manages the settings about the sheet management. The settings about the sheet management include a setting of a text displayed on the screen about the sheet management, a setting of the display unit system (millimeter or inch) of a sheet size, for example. 
       FIG. 5  is a view showing an example of a top screen  500  displayed on the external display device  113  of the print control apparatus  102  in  FIG. 1 . The external display device  113  displays the top screen  500  based on the video signal received from the display controller  412 . Specifically, the video signal corresponds to the image data of the top screen  500  drawn in the video memory of the display controller  412 . The information about the sheet feed unit  116  of the image forming apparatus  103  connected to the print control apparatus  102  is displayed on the top screen  500 . 
     When the sheet management application  453  starts, the controller  400  obtains device configuration information mentioned later from the image forming apparatus  103  connected to the print control apparatus  102  and displays the top screen  500  on the external display device  113  on the basis of the device configuration information. In  FIG. 5 , the information about the sheet feed unit  116  that consists of eight sheet feed cassettes is displayed. Sheet-feed-cassette buttons  510 ,  511 ,  512 ,  513 ,  514 ,  515 ,  516 , and  517  correspond to the respective sheet feed cassettes. For example, when a user selects the sheet-feed-cassette button  510  by operating the pointing device  115 , a sheet-feed-cassette screen  900  in  FIG. 9  mentioned later concerning the sheet feed cassette corresponding to the sheet-feed-cassette button  510  is displayed on the external display device  113 . The attributes, such as a type, size, basis weight, and remaining amount, about the sheets stored in a sheet feed cassette are displayed on a corresponding one of the sheet-feed-cassette button  510  through  517 . When receiving a change event notification from the image forming apparatus  103 , the controller  400  obtains sheet-feed-cassette information mentioned later from the image forming apparatus  103 . The change event notification shows that the sheet-feed-cassette information is changed because the state of a sheet feed cassette of the sheet feed unit  116  varies. The controller  400  displays the attributes of which contents are updated on the basis of the obtained sheet-feed-cassette information on the sheet-feed-cassette buttons  510  through  517 . 
     Sheet-feed-cassette open buttons  520 ,  521 ,  522 ,  523 ,  524 ,  525 ,  526 , and  527  are used to instruct the corresponding sheet feed cassettes to open. For example, when a user selects the sheet-feed-cassette open button  520 , the sheet feed cassette corresponding to the sheet-feed-cassette open button  520  opens. A sheet list button  501  is used to instruct the controller  400  to display a sheet list window  530 . When a user selects the sheet list button  501 , the controller  400  display the sheet list window  530  in a state superimposed on the top screen  500 . A setting button  502  is used to change a system configuration of the sheet management application  453 . 
       FIG. 6  is a flowchart showing procedures of a top-screen-display control process executed by the print control apparatus  102  in  FIG. 1 . The process in  FIG. 6  is achieved because the CPU  401  runs programs that are developed onto the RAM  402 . The process in  FIG. 6  is executed when the sheet management application  453  starts, for example. 
     As shown in  FIG. 6 , the CPU  401  inquires of the image forming apparatus  103  connected to the print control apparatus  102  about apparatus type information including information showing the apparatus type of the image forming apparatus  103  concerned, and obtains the apparatus type information from the image forming apparatus  103  (step S 601 ). Next, the CPU  401  determines the apparatus type of the image forming apparatus  103  on the basis of the apparatus type information obtained in the step S 601  and apparatus-type discrimination information held beforehand in the ROM  403  etc. (step S 602 ). The apparatus-type discrimination information includes information showing apparatus types that are beforehand registered into the print control apparatus  102 , for example. Next, the CPU  401  inquires of the image forming apparatus  103  about apparatus configuration information and obtains the apparatus configuration information from the image forming apparatus  103  (step S 603 ). The apparatus configuration information includes information showing the reading device  117  and the sheet feed unit  116  that are connected to the image forming apparatus  103  as options, for example. Next, the CPU  401  determines devices (hereinafter referred to as “optional connected devices”) connected to the image forming apparatus  103  as options on the basis of the obtained apparatus configuration information (step S 604 ). 
     Next, the CPU  401  inquires of the image forming apparatus  103  about the sheet-feed-cassette information and obtains the sheet-feed-cassette information from the image forming apparatus  103  (step S 605 ). The sheet-feed-cassette information includes configuration information about the sheet feed unit  116 , sheet attributes, and automatic pull-out capabilities. The configuration information about the sheet feed unit  116  shows the configuration of the sheet feed unit  116 , such as the sheet feed cassettes, a manual feed tray, and a long sheet tray. The sheet attributes show a type and size of sheets stored in each sheet feed cassette of the sheet feed unit  116 . The automatic pull-out capability shows whether each sheet feed cassette of the sheet feed unit  116  is configured to enable automatic pull-out in response to selection of the sheet-feed-cassette open button. Next, the CPU  401  determines the configuration of the sheet feed unit  116  on the basis of the sheet-feed-cassette information received in the step S 605  (step S 606 ). In the step S 606 , the CPU  401  determines the number of the sheet feed cassettes that constitute the sheet feed unit  116  and determines whether each sheet feed cassette that constitutes the sheet feed unit  116  can be automatically pulled out in response to selection of the corresponding sheet-feed-cassette open button, for example. Next, the CPU  401  generates contents of the sheet-feed-cassette buttons  510  through  517  displayed on the top screen  500  on the basis of the determination result in the step S 606  (step S 607 ). The contents of the sheet-feed-cassette buttons  510  through  517  are displayed on the sheet-feed-cassette buttons  510  through  517 . The contents of each the sheet-feed-cassette buttons  510  through  517  include the attributes, such as a type, size, basis weight, and remaining amount, about the sheets stored in a corresponding sheet feed cassette. Moreover, the contents of a sheet-feed-cassette button corresponding to a sheet feed cassette that is configured to enable the automatic pull-out in response to the selection of a sheet-feed-cassette open button include information about a sheet-feed-cassette open button displayed on the sheet-feed-cassette button in addition to the above-mentioned contents. 
     Next, the CPU  401  inquires of the image forming apparatus  103  about the sheet list information and obtains the sheet list information from the image forming apparatus  103  (step S 608 ). The sheet list information shows a list of sheets of which the attributes and adjustment values are already registered to the print control apparatus  102 , for example. Next, the CPU  401  generates information about the sheet list window  530  displayed on the top screen  500  on the basis of the obtained sheet list information (step S 609 ). Next, the CPU  401  inquires of the image forming apparatus  103  about the adjustment values and obtains the adjustment values from the image forming apparatus  103  (step S 610 ). Next, the CPU  401  generates adjustment presence information on the basis of the obtained adjustment values (step S 611 ). In the step S 611 , when the adjustment value has not been changed from a default value, the CPU  401  generates “not adjusted” as the adjustment presence information. Moreover, when the adjustment value has been changed from the default value, the CPU  401  generates “adjusted” as the adjustment presence information. Next, the CPU  401  displays the top screen  500 , which is generated on the basis of the apparatus type information, the apparatus configuration information, the contents of the sheet-feed-cassette buttons  510  through  517 , the information about the sheet list window  530 , and the adjustment presence information, on the external display device  113  (step S 612 ). Next, the CPU  401  issues a registration request of the transmission destination of the change event notification mentioned above to the image forming apparatus  103  (step S 613 ). When receiving the registration request, the image forming apparatus  103  sets the transmission destination of the change event notification to the print control apparatus  102 . Thereby, the image forming apparatus  103  transmits the change event notification to the print control apparatus  102 , when at least one of the sheet-feed-cassette information and the sheet information of the image forming apparatus  103  is changed. After that, the top-screen-display control process is finished. 
     Although the above-mentioned process in  FIG. 6  describes the case where the execution trigger of the top-screen-display control process is the start of the sheet management application  453 , the execution trigger of the top-screen-display control process is not restricted to this. For example, the process in FIG.  6  may be started when the sheet-feed-cassette information or the sheet information is updated in the image forming apparatus  103 . 
       FIG. 7  is a flowchart showing procedures of an initialization process executed by the image forming apparatus  103  in  FIG. 1 . The process in  FIG. 7  is achieved because the CPU  301  runs programs that are developed onto the RAM  302 . The process in  FIG. 7  is executed in starting the image forming apparatus  103 , for example. 
     As shown in  FIG. 7 , the CPU  301  obtains the information that shows the apparatus type of the image forming apparatus  103  from the external storage unit  311 , and generates apparatus type information on the basis of the obtained information (step S 701 ). Next, the CPU  301  obtains the information that shows the reading device  117  and sheet feed unit  116 , which are connected to the image forming apparatus  103  as options, from the external storage unit  311 , and generates the apparatus configuration information on the basis of the obtained information (step S 702 ). Next, the CPU  301  obtains the configuration information about the sheet feed unit  116 , the sheet attributes, and the automatic pull-out capabilities from the external storage unit  311 , and generates the sheet-feed-cassette information on the basis of these pieces of obtained information (step S 703 ). Next, the CPU  301  obtains the sheet information about the sheets that have been already registered to the print control apparatus  102  from the external storage unit  311 , and generates the sheet list information on the basis of the obtained sheet information (step S 704 ). Next, the CPU  301  obtains the adjustment values of all the adjustable items in the image forming apparatus  103  from the external storage unit  311  (step S 705 ). Next, the CPU  301  waits until receiving an access request from an external apparatus. When an access request is received from an external apparatus, for example, the print control apparatus  102 , the CPU  301  determine whether an inquiry about the apparatus type information is received from the print control apparatus  102  (step S 706 ). 
     As a result of the determination in the step S 706 , when the inquiry about the apparatus type information is not received from the print control apparatus  102 , the initialization process proceeds to a step S 708  mentioned later. As a result of the determination in the step S 706 , when the inquiry about the apparatus type information is received from the print control apparatus  102 , the CPU  301  transmits the apparatus type information generated in the step S 701  to the print control apparatus  102  (step S 707 ). Next, the CPU  301  determines whether an inquiry about the apparatus configuration information is received from the print control apparatus  102  (step S 708 ). 
     As a result of the determination in the step S 708 , when the inquiry about the apparatus configuration information is not received from the print control apparatus  102 , the initialization process proceeds to a step S 710  mentioned later. As a result of the determination in the step S 708 , when the inquiry about the apparatus configuration information is received from the print control apparatus  102 , the CPU  301  transmits the apparatus configuration information generated in the step S 702  to the print control apparatus  102  (step S 709 ). Next, the CPU  301  determines whether an inquiry about the sheet-feed-cassette information is received from the print control apparatus  102  (step S 710 ). 
     As a result of the determination in the step S 710 , when the inquiry about the sheet-feed-cassette information is not received from the print control apparatus  102 , the initialization process proceeds to a step S 712  mentioned later. As a result of the determination in the step S 710 , when the inquiry about the sheet-feed-cassette information is received from the print control apparatus  102 , the CPU  301  transmits the sheet-feed-cassette information generated in the step S 703  to the print control apparatus  102  (step S 711 ). Next, the CPU  301  determines whether an inquiry about the sheet list information is received from the print control apparatus  102  (step S 712 ). 
     As a result of the determination in the step S 712 , when the inquiry about the sheet list information is not received from the print control apparatus  102 , the initialization process proceeds to a step S 714  mentioned later. As a result of the determination in the step S 712 , when the inquiry about the apparatus type information is received from the print control apparatus  102 , the CPU  301  transmits the sheet list information generated in the step S 704  to the print control apparatus  102  (step S 713 ). Next, the CPU  301  determines whether an inquiry about the adjustment values is received from the print control apparatus  102  (step S 714 ). 
     As a result of the determination in the step S 714 , when the inquiry about the adjustment values is not received from the print control apparatus  102 , the initialization process proceeds to a step S 716  mentioned later. As a result of the determination in the step S 714 , when the inquiry about the adjustment values is received from the print control apparatus  102 , the CPU  301  transmits the adjustment values obtained in the step S 705  to the print control apparatus  102  (step S 715 ). Next, the CPU  301  determines whether the registration request of the transmission destination of the change event notification is received from the print control apparatus  102  (step S 716 ). 
     As a result of the determination in the step S 716 , when the registration request of the transmission destination of the change event notification is not received from the print control apparatus  102 , the initialization process proceeds to a step S 718  mentioned later. As a result of the determination in the step S 716 , when the registration request of the transmission destination of the change event notification is received from the print control apparatus  102 , the CPU  301  performs a registration process (step S 717 ) and registers the print control apparatus  102  as the transmission destination of the change event notification. Next, the CPU  301  determines whether the processes corresponding to the inquiries and the registration request received from the print control apparatus  102  have been finished (step S 718 ). For example, when all of the processes in the steps S 707 , S 709 , S 711 , S 713 , S 715 , and S 717  are completed, the CPU  301  determines that the processes corresponding to the inquiries and the registration request received from the print control apparatus  102  have been finished. In the meantime, when at least one of the processes in the steps S 707 , S 709 , S 711 , S 713 , S 715 , and S 717  is not completed, the CPU  301  determines that the processes corresponding to the inquiries and the registration request received from the print control apparatus  102  have not been finished. 
     As a result of the determination in the step S 718 , when the processes corresponding to the inquiries and the registration request received from the print control apparatus  102  have not been finished, the initialization process returns to the step S 706 . As a result of the determination in the step S 718 , when the processes corresponding to the inquiries and the registration request received from the print control apparatus  102  have been finished, the initialization process is finished. 
       FIG. 8  is a view showing an example of the sheet setting management table  800  managed by the sheet management application  453  in  FIG. 4B . The sheet management application  453  is able to edit, add, delete, and search the sheet information in the sheet setting management table  800 . The sheet setting management table  800  is a management table for managing the sheet information for every sheet ID and is stored in the external storage unit  409  that is a nonvolatile storage device. Although the embodiment describes the configuration that the sheet setting management table  800  is stored in the external storage unit  409 , the storage location of the sheet setting management table  800  is not limited to the external storage unit  409 . For example, the sheet setting management table  800  may be stored in the external storage unit  311  of the image forming apparatus  103 . In such a configuration, the print control apparatus  102  obtains the sheet setting management table  800  from the image forming apparatus  103  and stores the sheet setting management table  800  concerned into the RAM  402 . The sheet management application  453  manages the sheet setting management table  800  stored in the RAM  402 . 
     In the sheet setting management table  800 , the attributes and the adjustment values of the adjustment items of a sheet are registered in association with a sheet ID that specifies a sheet. Specifically, the sheet attributes include a sheet name, basis weight, size, width, height, and surface nature. The adjustment items include a sheet conveyance speed of the first fixing unit  211 , a sheet conveyance speed of the second fixing unit  213 , a primarily transfer voltage, an image position, and a secondary transfer voltage, for example. 
       FIG. 9  is a view showing an example of the sheet-feed-cassette screen displayed on the external display device  113  in selecting the sheet-feed-cassette button  510  on the top screen  500  in  FIG. 5 . The sheet-feed-cassette screen  900  is provided with a sheet list display area  901 , a sheet information display area  902 , a detailed adjustment button  903 , an OK button  904 , and a cancel button  905 . Furthermore, the sheet-feed-cassette screen  900  is provided with a pull down menu  906  for selecting a display method of the sheet list and a retrieval word input area  907 . 
     The sheet list is displayed in the sheet list display area  901 . In  FIG. 9 , the types of the sheets are displayed in a column direction and the attributes, such as the basis weight and size, are displayed in a row direction. In the sheet list display area  901 , the information about the sheet selected by a user is highlighted so that the user can easily recognize the selection state of the sheet. In the embodiment, when a user selects the sheet-feed-cassette button  510 , the sheet-feed-cassette screen  900  is displayed in the state where the sheet information set to the sheet feed cassette corresponding to the sheet-feed-cassette button  510  is selected in the sheet list display area  901 . When the user selects another sheet in the sheet list display area  901 , the information about the selected sheet is displayed in the sheet information display area  902 . When the user selects the OK button  904  in the state where the other sheet is selected in the sheet list display area  901 , the controller  400  performs sheet setting to the image forming apparatus  103  on the basis of the information about the sheet that the user selects in the sheet list display area  901 . In the meantime, when the user selects the cancel button  905  in the state where the other sheet is selected in the sheet list display area  901 , the controller  400  closes the sheet-feed-cassette screen  900  without performing the sheet setting to the image forming apparatus  103 . 
     In the sheet information display area  902 , information that the user uses frequently is displayed from among the pieces of sheet information that are selected by the user. Specifically, the information includes a name of a sheet and some adjustment items, such as image position adjustment, adjustment of a secondary transfer voltage, a curl correction amount, adjustment of glossiness/black rank, correction of blank area in a rear end part, a saddle stitch setting, and adjustment of flow rate of a sheet fan. In the sheet information display area  902 , a determination result of whether an adjustment value of each adjustment item has been changed from an initial value of the image forming apparatus  103  is displayed. For example, a message “not adjusted” is displayed to an adjustment item of which an adjustment value is not changed from an initial value, and a message “adjusted” is displayed to an adjustment item of which an adjustment value is changed from an initial value. Moreover, in the sheet information display area  902 , the adjustment buttons are displayed to the adjustment items of which the adjustment values can be changed from the print control apparatus  102 . For example, when the user selects the adjustment button  908 , an automatic adjustment setting screen  1300  of the secondary transfer voltage shown in  FIG. 13A  mentioned later is displayed on the external display device  113 . 
     The detailed adjustment button  903  is used to instruct display of detailed information that is not displayed on the sheet information display area  902 . In the pull-down menu  906 , options for filtering and displaying the sheet displayed on the sheet list display area  901  can be displayed. The retrieval word input area  907  is used to input a keyword that the user retrieves a desired sheet from among the sheets displayed in the sheet list display area  901 . Incremental search is available in the retrieval word input area  907 . Whenever a character is input, the sheets are searched automatically. 
     Next, the adjustment of the secondary transfer voltage in the embodiment will be described. For example, when a sheet of a type that is different in the water content or the resistance is used to print, optimal transfer may be impossible when a secondary transfer voltage is a default value. The secondary transfer voltage is set to a value that is necessary to transfer the toner on the intermediate transfer medium and does not cause abnormal discharge. For example, when resistance of a sheet used to print is larger than a standard value, the default value of the secondary transfer voltage is short, and it is necessary to apply a voltage larger than the default value as the secondary transfer voltage. Moreover, when water content of a sheet used to print is smaller than a standard value, abnormal discharge tends to occur, which causes image defect when the secondary transfer voltage is the default value. In such a case, it is necessary to apply a voltage smaller than the default value as the secondary transfer voltage. In this way, it is necessary to control the secondary transfer voltage to a suitable value in accordance with the type of the sheet used to print. Taking this into consideration, the image forming apparatus  103  automatically adjusts the secondary transfer voltage according to the instruction received from the print control apparatus  102  in the embodiment. In the automatic adjustment of the secondary transfer voltage, the image forming apparatus  103  prints a coarse adjustment chart (first chart) shown in  FIG. 10A  or a fine adjustment chart (second chart) shown in  FIG. 10B , reads the printed chart with the reading device  117 , and determines the adjustment value of the secondary transfer voltage so that the transfer efficiency will fall within a stipulated range. 
     The coarse adjustment chart and fine adjustment chart are formed while changing the secondary transfer voltage by a predetermined pitch width so as to print different patches for the respective secondary transfer voltages. For example, the coarse adjustment chart is formed while changing the secondary transfer voltage from the adjustable minimum value 1750V to the adjustable maximum value 3250V at the pitch width 150V, so that blue solid patches  1001  and black solid patches  1002  are printed. The coarse adjustment chart is used to adjust the secondary transfer voltage roughly. For example, the coarse adjustment chart is used in a case where the secondary transfer voltage is automatically adjusted to an unadjusted sheet. 
     The fine adjustment chart is formed while changing the secondary transfer voltage within a specific range from 2500V to 3000V at the pitch width 50V in the adjustable range of the secondary transfer voltage, so that blue solid patches  1003  and black solid patches  1004  are printed. In print of the fine adjustment chart, the secondary transfer voltage can be adjusted at the pitch width finer than that of the coarse adjustment chart. The fine adjustment chart is used when the secondary transfer voltage is adjusted more finely after adjustment by using the coarse adjustment chart or when the secondary transfer voltage to the adjusted sheet is readjusted because of a lapse of time. The reading device  117  reads these charts with the image pickup unit  325  according to instructions from the CPU  322  and stores the read result into the RAM  324 . Moreover, the CPU  301  is notified of the read result through the communication I/F  321  and reading-device I/F  315 . The CPU  301  stores the obtained reading result into the RAM  302  and determines whether both the transcriptional efficiencies of the blue solid patches and the black solid patches fall within the stipulated range. 
       FIG. 11  is a graph showing an example of a result that the reading device  117  in  FIG. 1  reads. In the example in  FIG. 11 , 90% or more of the transfer efficiency of the blue solid is OK and “8” or more of the black rank is OK. In  FIG. 11 , when the secondary transfer voltage falls within the range 2650V through 2800V, the printed chart satisfies both the condition of the transfer efficiency of the blue solid and the black rank. The CPU  301  stores the smallest voltage 2650V within the range 2650V through 2800V into the external storage unit  311 , for example, and decides the adjustment value of the secondary transfer voltage of the applicable sheet on the basis of this voltage value. Although the adjustment value of the secondary transfer voltage is decided on the basis of the smallest voltage 2650V within the range 2650V through 2800V in the embodiment, the present invention is not restricted to this. For example, the adjustment value of the secondary transfer voltage may be decided on the basis of the voltage value that maximizes the transfer efficiency of the blue solid and the black rank within the range 2650V through 2800V. Moreover, when “front side only” is set as the setting about the automatic adjustment of the secondary transfer voltage, the adjustment value of the secondary transfer voltage only for the front side is stored. In the meantime, when “both sides” is set as the setting about the automatic adjustment of the secondary transfer voltage, the adjustment values for the front side and back side are stored, respectively. When the “both sides” is set as the setting about the automatic adjustment of the secondary transfer voltage, blue solid patches and black solid patches are printed on both sides so that the patches in the front side will not overlap with the patches in the back side in order to avoid influence on the reading result. 
       FIG. 12  is a flowchart showing procedures of a secondary-transfer-voltage adjustment process executed by the print system  100  in  FIG. 1 . The secondary-transfer-voltage adjustment process includes a process by the sheet management application  453  and a process by the image forming apparatus  103 . The process by the sheet management application  453  is controlled by the sheet management application  453  and is achieved because the CPU  401  runs the program that is developed onto the RAM  402 . The process by the image forming apparatus  103  is achieved because the CPU  301  runs the program that is developed onto the RAM  302 . In the secondary-transfer-voltage adjustment process, the process accompanied by communication between the sheet management application  453  and the controller  300  is executed by the CPUs  301  and  401  through the LAN controller  306 , control cable  108 , and LAN controller  406 . The secondary-transfer-voltage adjustment process is executed when a user selects a sheet feed button corresponding to a sheet feed cassette subjected to the automatic adjustment from among the sheet-feed-cassette buttons  510  through  517  on the top screen  500  and selects the adjustment button  908  on the sheet-feed-cassette screen  900  displayed on the external display device  113 . It should be noted that the secondary-transfer-voltage adjustment process assumes that the above-mentioned top-screen-display control process has been already executed. 
     As shown in  FIG. 12 , the sheet management application  453  first determines whether the reading device  117  is connected to the image forming apparatus  103  on the basis of the apparatus configuration information obtained in the step S 603  (step S 1201 ). 
     As a result of the determination in the step S 1201 , when the reading device  117  is not connected to the image forming apparatus  103 , the secondary-transfer-voltage adjustment process proceeds to a step S 1216  mentioned later. As a result of the determination in the step S 1201 , when the reading device  117  is connected to the image forming apparatus  103 , the sheet management application  453  displays the automatic adjustment setting screen  1300  about the secondary transfer voltage on the external display device  113  as shown in  FIG. 13A  (step S 1202 ). 
     The automatic adjustment setting screen  1300  about the secondary transfer voltage is provided with a chart-type setting area  1301 , a print-side setting area  1302 , an execution button  1303 , and a cancel button  1304 . The chart-type setting area  1301  includes radio buttons that are used to set up a type of a chart that will be printed in the automatic adjustment of the secondary transfer voltage. The user can select either one of “coarse adjustment” that shows the fine adjustment chart and “fine adjustment” that shows the coarse adjustment chart by operating the radio buttons. The print-side setting area  1302  includes radio buttons that are used to set up a print side that is subjected to the automatic adjustment of the secondary transfer voltage. The user can select either one of “front side only” showing that only the front side is subjected to the automatic adjustment of the secondary transfer voltage and “both sides” showing that the both sides are subjected to the automatic adjustment of the secondary transfer voltage by operating the radio buttons. The execution button  1303  is used to instruct the image forming apparatus  103  to execute the automatic adjustment of the secondary transfer voltage by using the settings on the automatic adjustment setting screen  1300  about the secondary transfer voltage. The cancel button  1304  is used to instruct the image forming apparatus  103  to close the automatic adjustment setting screen  1300  about the secondary transfer voltage and to display of the sheet-feed-cassette screen  900  again without instructing the image forming apparatus  103  to execute the automatic adjustment of the secondary transfer voltage. The sheet management application  453  waits until the user selects the execution button  1303  or the cancel button  1304 . 
     When the user selects the execution button  1303  or the cancel button  1304 , the sheet management application  453  determines which of the execution button  1303  or the cancel button  1304  is selected by the user (step S 1203 ). 
     As a result of the determination in the step S 1203 , when the user selects the cancel button  1304 , the secondary-transfer-voltage adjustment process is finished. As a result of the determination in the step S 1203 , when the user selects the execution button  1303 , the secondary-transfer-voltage adjustment process proceeds to a step S 1204 . In the step S 1204 , the sheet management application  453  stores (holds) the adjustment value of the secondary transfer voltage of the sheet stored in the sheet feed cassette selected by the user on the top screen  500  into the RAM  402 . Next, the sheet management application  453  instructs the image forming apparatus  103  to execute the automatic adjustment of the secondary transfer voltage for the sheet stored in the sheet feed cassette selected by the user on the basis of the settings on the automatic adjustment setting screen  1300  about the secondary transfer voltage (step S 1205 ). 
     When receiving the execution instruction (step S 1206 ), the CPU  301  of the image forming apparatus  103  automatically adjusts the secondary transfer voltage for the sheet stored in the sheet feed cassette selected by the user according to the received execution instruction (step S 1207 ). In the step S 1207 , the coarse adjustment chart in  FIG. 14A  or the fine adjustment chart in  FIG. 14B  is printed according to the setting set in the chart-type setting area  1301 . The image forming apparatus  103  reads the chart with the reading device  117  and decides the adjustment value of the secondary transfer voltage so that the transfer efficiency falls within the stipulated range. Although the configurations of the charts in  FIG. 14A  and  FIG. 14B  are basically identical to that in  FIG. 10A  and  FIG. 10B , they differ in that adjustment values  1401  and  1402  are printed in association with the patches. Although the printed adjustment values are not used in the automatic adjustment of the secondary transfer voltage, they are used when the user readjusts the secondary transfer voltage adjusted by the automatic adjustment. When the automatic adjustment is completed, the CPU  301  stores the adjustment value of the secondary transfer voltage after adjustment into the external storage unit  311 . Moreover, the CPU  301  transmits an automatic adjustment completion notice showing that the automatic adjustment of the secondary transfer voltage has been completed to the print control apparatus  102  (step S 1208 ). 
     When receiving the automatic adjustment completion notice (step S 1209 ), the sheet management application  453  of the print control apparatus  102  requests the adjustment value of the secondary transfer voltage after adjustment from the image forming apparatus  103  (step S 1210 ). When receiving the adjustment value of the secondary transfer voltage after adjustment (step S 1211 ), the CPU  301  of the image forming apparatus  103  transmits the adjustment value of the secondary transfer voltage after the adjustment stored in the external storage unit  311  to the print control apparatus  102  (step S 1212 ). 
     When receiving the adjustment value of the secondary transfer voltage after adjustment (step S 1213 ), the sheet management application  453  of the print control apparatus  102  displays an execution result screen  1305  shown in  FIG. 13B  on the external display device  113  (step S 1214 ). The execution result screen  1305  is provided with an execution-result display area  1306 , a manual adjustment button (an object)  1307 , and an OK button  1308 . The adjustment value stored in the step S 1204  (i.e., the adjustment value of the secondary transfer voltage before the automatic adjustment in the step S 1207 ) and the adjustment value of the secondary transfer voltage after the automatic adjustment in the step S 1207  are displayed in the execution-result display area  1306 .  FIG. 13B  shows that the adjustment value of the secondary transfer voltage of the front side is changed into “+2” from “0”, and the adjustment value of the secondary transfer voltage of the back side is changed into “+1” from “0”. The manual adjustment button  1307  is used to display a manual adjustment screen  1309  shown in  FIG. 13C . The OK button  1308  is used to close the execution result screen  1305 . The sheet management application  453  waits until the user selects the manual adjustment button  1307  or the OK button  1308 . When the user selects the manual adjustment button  1307  or the OK button  1308 , the sheet management application  453  determines which of the manual adjustment button  1307  or the OK button  1308  is selected by the user (step S 1215 ). 
     As a result of the determination in the step S 1215 , when the user selects the OK button  1308 , the secondary-transfer-voltage adjustment process is finished. As a result of the determination in the step S 1215 , when the user selects the manual adjustment button  1307 , the sheet management application  453  displays the manual adjustment screen (adjustment screen)  1309  on the external display device  113  (step S 1216 ). The manual adjustment screen  1309  is provided with an adjustment value input area  1310 , a chart print button  1311 , an OK button  1312 , and a cancel button  1313 . The adjustment value of the secondary transfer voltage is designated in the adjustment value input area  1310 . The user can readjust the secondary transfer voltage adjusted by the automatic adjustment by directly inputting an adjustment value of the secondary transfer voltage into a text box or by operating plus/minus buttons to designate an adjustment value of the secondary transfer voltage. In the step S 1216 , the manual adjustment screen  1309  is displayed in the state where the adjustment value of the secondary transfer voltage after adjustment received from the image forming apparatus  103  in the step S 1213  are input into the adjustment value input area  1310 . The chart print button  1311  is used to display a chart setting screen  1314  shown in  FIG. 13D . The OK button  1312  is used to transmit the adjustment value input into the adjustment value input area  1310  to the image forming apparatus  103 . The cancel button  1313  is used to close the manual adjustment screen  1309 . 
     Next, the sheet management application  453  determines whether the user selects the chart print button  1311  on the manual adjustment screen  1309  (step S 1217 ). As a result of the determination in the step S 1217 , when the user does not select the chart print button  1311  on the manual adjustment screen  1309 , the secondary-transfer-voltage adjustment process proceeds to a step S 1221  mentioned later. 
     As a result of the determination in the step S 1217 , when the user selects the chart print button  1311  on the manual adjustment screen  1309 , the sheet management application  453  displays the chart setting screen  1314  on the external display device  113 . The chart setting screen  1314  is provided with a chart-type setting area  1315 , a print-side setting area  1316 , a sheet-feed-cassette setting area  1317 , a print button  1318 , and a cancel button  1319 . The chart-type setting area  1315  includes radio buttons that can set either one of “near set voltage value” and “all”. When the “near set voltage value” is selected, a fine adjustment chart is printed while changing the secondary transfer voltage gradually in a plus direction and a minus direction on the basis of the adjustment value input into the adjustment value input area  1310 . When the “all” is selected, a coarse adjustment chart is printed while changing the secondary transfer voltage gradually from the minimum adjustable value to the maximum adjustable value of the secondary transfer voltage. The print-side setting area  1316  includes radio buttons that are used to select either one of “front side only” and “both sides” as with the print-side setting area  1302 . A numerical value showing the sheet feed cassette selected by the user on the top screen  500  is set to the sheet-feed-cassette setting area  1317 . The print button  1318  is used to instruct the image forming apparatus  103  to output a chart on the basis of the settings on the manual adjustment screen  1309  and chart setting screen  1314 . The cancel button  1319  is used to close the chart setting screen  1314  and to display the manual adjustment screen  1309  again. 
     When the user selects the print button  1318 , the sheet management application  453  instructs the image forming apparatus  103  to output a chart including the settings on the manual adjustment screen  1309  and chart setting screen  1314  (step S 1218 , a chart-print instruction unit). Moreover, the sheet management application  453  switches the screen of the external display device  113  from the chart setting screen  1314  to the manual adjustment screen  1309 . 
     When receiving the chart output instruction from the print control apparatus  102  (YES in a step S 1219 ), the CPU  301  of the image forming apparatus  103  controls the print engine  210  to print the chart of the secondary transfer voltage according to the chart output instruction (step S 1220 ). In the step S 1220 , the coarse adjustment chart in  FIG. 14A  or the fine adjustment chart in  FIG. 14B  is printed according to the settings in the print-side setting area  1316 . It should be noted that the CPU  301  proceeds with the process to a step S 1223  mentioned later without printing the chart to a sheet when the chart output instruction is not received from the print control apparatus  102 . 
     The user checks the chart printed by the image forming apparatus  103 . When the intended result is obtained by changing the adjustment value of the secondary transfer voltage to the value input on the manual adjustment screen  1309 , the user selects the OK button  1312  on the manual adjustment screen  1309  currently displayed on the external display device  113  of the print control apparatus  102 . In the meantime, when the intended result is not obtained even if the adjustment value of the secondary transfer voltage is changed to the value input on the manual adjustment screen  1309 , and when the user wants to return the adjustment value to the adjustment value obtained by the automatic adjustment, the user selects the cancel button  1313  on the manual adjustment screen  1309 . 
     The sheet management application  453  of the print control apparatus  102  determines whether the user selects either one of the OK button  1312  and the cancel button  1313  on the manual adjustment screen  1309  (step S 1221 ). 
     As a result of the determination in the step S 1221 , when the user selects the cancel button  1313  on the manual adjustment screen  1309 , the secondary-transfer-voltage adjustment process is finished. As a result of the determination in the step S 1221 , when the user selects the OK button  1312  on the manual adjustment screen  1309 , the secondary-transfer-voltage adjustment process proceeds to a step S 1222 . In the step S 1222 , the sheet management application  453  transmits the adjustment value input into the adjustment value input area  1310  in the manual adjustment screen  1309  to the image forming apparatus  103 . After that, the sheet management application  453  finishes this process. 
     The CPU  301  of the image forming apparatus  103  stores the received adjustment value into the external storage unit  311  as the adjustment value of the secondary transfer voltage for the sheet stored in the sheet feed cassette selected by the user on the top screen  500  (step S 1223 ) and finishes this process. 
     According to the above-mentioned embodiment, when the adjustment value obtained by the automatic adjustment of the secondary transfer voltage is received, the adjustment value obtained by the automatic adjustment of the secondary transfer voltage and the manual adjustment button  137  are displayed on the execution result screen  1305  (on the same screen). That is, the user is not required to perform a plurality of operations for displaying the manual adjustment screen  1309  and the information about the adjustment value of the secondary transfer voltage that is necessary to determine the necessity of readjustment of the secondary transfer voltage. Accordingly, the operability in readjusting the secondary transfer voltage that has been adjusted is improvable. 
     Moreover, when the adjustment value obtained by the automatic adjustment of the secondary transfer voltage is received, the adjustment values of the secondary transfer voltage before and after the automatic adjustment are displayed together with the manual adjustment button  1307  on the execution result screen  1305  in the above-mentioned embodiment. Thereby, the user easily determines whether the readjustment of the secondary transfer voltage is necessary on the basis of the difference between the adjustment values of the secondary transfer voltage before and after the automatic adjustment. 
     Although the present invention has been described using the above-mentioned embodiment, the present invention is not limited to the above-mentioned embodiment. For example, when the user who selected the manual adjustment button  1307  selects the chart print button  1311 , the chart setting screen  1314  may be displayed in a state where the “near set voltage value” is selected in the chart-type setting area  1315 . Since the adjustment value has been roughly adjusted by the automatic adjustment, when the user readjusts the secondary transfer voltage adjusted by the automatic adjustment, it is considered that the secondary transfer voltage is subjected to the fine adjustment. In such a case, it is preferable to use the fine adjustment chart that enables to adjust the secondary transfer voltage at the pitch width finer than that of the coarse adjustment chart. As compared with this, when the user who selected the manual adjustment button  1307  selects the chart print button  1311 , the chart setting screen  1314  is displayed in the state where the “near set voltage value” is set in the chart-type setting area  1315  in the embodiment. The “near set voltage value” is the setting corresponding to the fine adjustment chart. Thereby, the time and effort of the user who sets the chart type is reducible in the readjustment of the adjustment value obtained by the automatic adjustment. 
     Moreover, when the user who selected the manual adjustment button  1307  selects the chart print button  1311 , the chart setting screen  1314  may be displayed in a state where the setting about the print side in the automatic adjustment is selected in the print-side setting area  1316  in the above-mentioned embodiment. The setting of the print side in the automatic adjustment is the setting set in the print-side setting area  1302  in the automatic adjustment setting screen  1300  of the secondary transfer voltage. Thereby, the time and effort of the user who sets up the print side is reducible in the readjustment of the adjustment value obtained by the automatic adjustment. 
     Moreover, when the user who selected the manual adjustment button  1307  selects the chart print button  1311 , the chart output instruction may be issued without displaying the chart setting screen  1314  in the above-mentioned embodiment. This chart output instruction includes the “near set voltage value” as the setting set in the chart-type setting area  1315  and the setting of the print side in the automatic adjustment as the setting set in the print-side setting area  1316 . Thereby, the time and effort of the user who sets up the various settings on the chart setting screen  1314  is reducible. 
     In the above-mentioned embodiment, when the fine adjustment chart is printed in the automatic adjustment of the secondary transfer voltage, the sheet management application  453  may control so as not to accept the operation of the chart output instruction from the user who selected the manual adjustment button  1307 . When the user readjusts the secondary transfer voltage that has been automatically adjusted as mentioned above, it is considered that the secondary transfer voltage is adjusted finely. That is, it is considered that an adjustment value near the adjustment value decided by the automatic adjustment is set up. In the meantime, as shown in  FIG. 14B , the fine adjustment chart printed in the automatic adjustment includes a plurality of patches corresponding to adjustment values near the adjustment value decided by the automatic adjustment in addition to a patch corresponding to the adjustment value decided by the automatic adjustment. Furthermore, the adjustment values are printed in association with the respective patches. There is extremely high possibility that the above-mentioned fine adjustment chart includes a patch corresponding to the adjustment value that the user inputs in the adjustment value input area  1310 . Accordingly, the user is able to readjust the secondary transfer voltage while visually checking the fine adjustment chart output in adjusting the secondary transfer voltage automatically. And there is no need of newly printing a chart. In the embodiment, when the fine adjustment chart is printed in the automatic adjustment of the secondary transfer voltage, the sheet management application  453  controls so as not to accept the operation of the chart output instruction from the user who selected the manual adjustment button  1307 . 
       FIG. 15  is a flowchart showing procedures of a secondary-transfer-voltage adjustment process executed by the print system  100  in  FIG. 1 . The secondary-transfer-voltage adjustment process in  FIG. 15  is similar to the secondary-transfer-voltage adjustment process in  FIG. 12 , and the subjects of the process in  FIG. 15  are the same as that of the process in  FIG. 12 . Hereinafter, process contents different from the secondary-transfer-voltage adjustment process in  FIG. 12  will be described. The secondary-transfer-voltage adjustment process in  FIG. 15  is also executed when the user selects a sheet feed button corresponding to a sheet feed cassette subjected to the automatic adjustment from among the sheet-feed-cassette buttons  510  through  517  on the top screen  500  and selects the adjustment button  908  on the sheet-feed-cassette screen  900  displayed on the external display device  113 . It should be noted that the secondary-transfer-voltage adjustment process in  FIG. 15  assumes that the above-mentioned top-screen-display control process has been already executed. 
     In the secondary-transfer-voltage adjustment process in  FIG. 15 , the process in the steps S 1201  through S 1216  is performed. Next, the sheet management application  453  of the print control apparatus  102  determines which of the coarse adjustment chart or the fine adjustment chart has been printed in the automatic adjustment of the secondary transfer voltage in the step S 1207  (step S 1501 ). 
     As a result of the determination in the step S 1501 , when the fine adjustment chart has been printed in the automatic adjustment of the secondary transfer voltage in the step S 1207 , the sheet management application  453  proceeds with the process to the step S 1221  without issuing the chart output instruction. At this time, the sheet management application  453  controls so as not to accept the operation of the chart output instruction from the user who selected the manual adjustment button  1307 . For example, the sheet management application  453  controls so as to prohibit the selection of the chart print button  1311  on the manual adjustment screen  1309 . Moreover, the sheet management application  453  controls so as not to display the chart print button  1311  on the manual adjustment screen  1309  as shown in  FIG. 16 . 
     As a result of the determination in the step S 1501 , when the coarse adjustment chart has been printed in the automatic adjustment of the secondary transfer voltage in the step S 1207 , the secondary-transfer-voltage adjustment process proceeds to a step S 1502 . In the step S 1502 , the sheet management application  453  instructs the image forming apparatus  103  to output a chart. This chart output instruction includes the “near set voltage value” as the setting in the chart-type setting area  1315  and the setting of the print side in the automatic adjustment as the setting in the print-side setting area  1316 . After that, the secondary-transfer-voltage adjustment process proceeds to the step S 1219 . 
     In the above-mentioned embodiment, when the fine adjustment chart has been printed in the automatic adjustment of the secondary transfer voltage, the sheet management application  453  controls so as not to accept the operation of the chart output instruction from the user who selected the manual adjustment button  1307 . This improves the operability in readjusting the adjusted secondary transfer voltage and prevents print of an unnecessary chart. 
     Moreover, in the above-mentioned embodiment, even when the fine adjustment chart is printed in the automatic adjustment of the secondary transfer voltage, when a predetermined condition is satisfied, the sheet management application  453  may control so as to accept the operation of the chart output instruction from the user who selected the manual adjustment button  1307 . The predetermined condition is satisfied when the user who selected the manual adjustment button  1307  inputs an adjustment value corresponding to a secondary transfer voltage that is not set in print of the fine adjustment chart into the adjustment value input area  1310 , for example. When the fine adjustment chart in  FIG. 14B  is printed during the automatic adjustment of the secondary transfer voltage, the user is able to check the transfer properties of the patches corresponding to the adjustment values “−1” through “9” from the fine adjustment chart. When the user wants to know a transfer property of a patch corresponding to an adjustment value “−2”, the user needs operations to input “−2” into the adjustment value input area  1310  and to select the chart print button  1311  to instruct output of a new chart. However, if the sheet management application  453  controls so as not to accept the chart output instruction from the user who selected the manual adjustment button  1307 , a new chart cannot be printed and the user cannot check a transfer property of a patch corresponding to a desired adjustment value. Against this, in the above-mentioned embodiment, even when the fine adjustment chart is printed in the automatic adjustment of the secondary transfer voltage, when the above-mentioned predetermined condition is satisfied, the sheet management application  453  controls so as to accept the operation of the chart output instruction from the user who selected the manual adjustment button  1307 . This does not obstruct the print of a necessary chart and prevents the damage to the operability. 
     The client computer  101  may be provided with the software module  451  including the sheet management application  453  in the above-mentioned embodiment. In such a case, the client computer  101  executes the secondary-transfer-voltage adjustment process mentioned above. This improves the operability in readjusting the adjusted secondary transfer voltage by a user from the client computer  101 . 
     Moreover, although the print control apparatus  102  is described as the independent apparatus that is separated from the image forming apparatus  103  in the above-mentioned embodiment, the image forming apparatus  103  may be provided with the functions of the print control apparatus  102 . In such a case, the image forming apparatus  103  executes the secondary-transfer-voltage adjustment process mentioned above. This improves the operability in readjusting the adjusted secondary transfer voltage by a user from the operation panel  105 . 
     OTHER EMBODIMENTS 
     Embodiment(s) of the present invention can also be realized by a computer of a system or apparatus that reads out and executes computer executable instructions (e.g., one or more programs) recorded on a storage medium (which may also be referred to more fully as a ‘non-transitory computer-readable storage medium’) to perform the functions of one or more of the above-described embodiment(s) and/or that includes one or more circuits (e.g., application specific integrated circuit (ASIC)) for performing the functions of one or more of the above-described embodiment(s), and by a method performed by the computer of the system or apparatus by, for example, reading out and executing the computer executable instructions from the storage medium to perform the functions of one or more of the above-described embodiment(s) and/or controlling the one or more circuits to perform the functions of one or more of the above-described embodiment(s). The computer may comprise one or more processors (e.g., central processing unit (CPU), micro processing unit (MPU)) and may include a network of separate computers or separate processors to read out and execute the computer executable instructions. The computer executable instructions may be provided to the computer, for example, from a network or the storage medium. The storage medium may include, for example, one or more of a hard disk, a random-access memory (RAM), a read only memory (ROM), a storage of distributed computing systems, an optical disk (such as a compact disc (CD), digital versatile disc (DVD), or Blu-ray Disc (BD)′), a flash memory device, a memory card, and the like. 
     While the present invention has been described with reference to exemplary embodiments, it is to be understood that the invention is not limited to the disclosed exemplary embodiments. The scope of the following claims is to be accorded the broadest interpretation so as to encompass all such modifications and equivalent structures and functions. 
     This application claims the benefit of Japanese Patent Application No. 2021-006601, filed Jan. 19, 2021, which is hereby incorporated by reference herein in its entirety.