Abstract:
An image forming apparatus includes a print engine configured to perform printing on a recording medium, a job issuing unit configured to issue a print job, two print control units configured to control the print engine in accordance with the issued print job, and a job allocating unit configured to allocate the print job to an appropriate print control unit, among the two print control units. If a last print job that is issued is for a first print control unit, the control of the print engine by the first print control unit in accordance with the last print job allocated to the first print control unit is not completed, and a next print job that is issued is for a second print control unit, the job allocating unit is configured to place on standby the allocation of the next print job to the second print control unit.

Description:
INCORPORATION BY REFERENCE 
     This application is based upon, and claims the benefit of priority from, corresponding Japanese Patent Application No. 2012-237535 filed in the Japan Patent Office on Oct. 29, 2012, the entire contents of which are incorporated herein by reference. 
     BACKGROUND 
     Unless otherwise indicated herein, the description in this section is not prior art to the claims in this application and is not admitted to be prior art by inclusion in this section. 
     The present disclosure relates to an image forming apparatus that performs printing on a recording medium. 
     A typical image forming apparatus includes a printer engine that performs printing on a print sheet, two controllers that control the printer engine in accordance with a print job, and a reception data allocation unit that allocates the print job to an appropriate controller among the two controllers. The reception data allocation unit determines whether reception data is mainly composed of text data or graphic data to allocate the print job to an appropriate controller in accordance with the type of the reception data. The reception data allocation unit allocates the reception data to a text data controller if the reception data allocation unit determines that the reception data is mainly composed of the text data, and allocates the reception data to a graphic data controller if the reception data allocation unit determines that the data is mainly composed of graphic data. 
     However, when the process time by the text data controller is different from that of the graphic data controller, a printout based on the data mainly composed of the text data and a printout based on the data mainly composed of the graphic data may possibly be outputted in an inappropriate sequence. 
     SUMMARY 
     According to an embodiment of the present disclosure, an image forming apparatus includes a print engine, a job issuing unit, two print control units, and a job allocating unit. The print engine performs printing on a recording medium. The job issuing unit issues a print job for the printing by the print engine. The two print control units control the print engine in accordance with the print job issued by the job issuing unit. The job allocating unit allocates the print job to an appropriate print control unit, among the two print control units. If a last print job is for a first print control unit, among of the two print control units, the control of the print engine by the first print control unit in accordance with the last print job allocated to the first print control unit is not completed, and a next print job is for a second print control unit, among the two print control units, the job allocating unit places on standby the allocation of the next print job to the second print control unit. 
     According to another embodiment of the present disclosure, an image forming method includes performing printing on a recording medium by a print engine; issuing a print job for printing by the print engine; controlling the print engine in accordance with the issued print job by two print control units; and allocating the issued print job to an appropriate print control unit, among the two print control units. If a last print job that is issued is for a first print control unit, among the two print control units, the control of the print engine by the first print control unit in accordance with the last print job allocated to the first print control unit is not completed, and a next print job that is issued is for a second print control unit, among the two print control units, the allocation of the next print job to the second print control unit is placed on standby. 
     Additional features and advantages are described herein, and will be apparent from the following Detailed Description and the figures. 
    
    
     
       BRIEF DESCRIPTION OF THE FIGURES 
       In the accompanying drawings: 
         FIG. 1  shows a block diagram illustrating a configuration of a network system according to an embodiment of the present disclosure; 
         FIG. 2  shows a block diagram illustrating a configuration of an MFP illustrated in  FIG. 1 ; 
         FIG. 3  shows a block diagram illustrating a configuration of an MFP main body illustrated in  FIG. 2 ; 
         FIG. 4  illustrates an example of job information illustrated in  FIG. 3 ; 
         FIG. 5  shows a block diagram illustrating a configuration of an option print control apparatus illustrated in  FIG. 2 ; 
         FIG. 6  shows a block diagram illustrating a configuration of a computer illustrated in  FIG. 1 ; 
         FIG. 7  illustrates a flow of a print job in the MFP illustrated in  FIG. 2 ; 
         FIG. 8  shows a flowchart illustrating a operation of an arbitrator illustrated in  FIG. 3  when the arbitrator is notified of a new print job by a job manager; 
         FIG. 9A  illustrates an example of queue managed by the arbitrator illustrated in  FIG. 3 ; 
         FIG. 9B  illustrates another example of queue managed by the arbitrator illustrated in  FIG. 3 , which is different from the example of queue illustrated in  FIG. 9A ; 
         FIG. 9C  illustrates another example of queue managed by the arbitrator illustrated in  FIG. 3 , which is different from the example of queues illustrated in  FIG. 9A  and  FIG. 9B ; and 
         FIG. 10  shows a flowchart illustrating an operation of the arbitrator illustrated in  FIG. 3  when the arbitrator is notified of completion of execution of a print job by a print system. 
     
    
    
     DETAILED DESCRIPTION 
     Example apparatus and method are described herein. Other example embodiments or features may further be utilized, and other changes may be made, without departing from the spirit or scope of the subject matter presented herein. In the following detailed description, reference is made to the accompanying drawings, which form a part thereof. 
     Embodiments of the present disclosure will herein be described with reference to the attached drawings. 
     The configuration of a network system according to an embodiment will now be described.  FIG. 1  shows a block diagram illustrating a configuration of a network system  10  according to an embodiment. 
     Referring to  FIG. 1 , the network system  10  includes a multifunction peripheral (“MFP”)  20  functioning as an image forming apparatus and a computer  60 , such as a personal computer (“PC”), capable of transmitting print data to the MFP  20 . The MFP  20  and the computer  60  are connected to each other via a network  11 , such as a local area network (“LAN”) or the Internet, so as to be capable of communicating with each other. 
       FIG. 2  shows a block diagram illustrating a configuration of the MFP  20 . 
     Referring to  FIG. 2 , the MFP  20  includes an MFP main body  30  and an option print control apparatus  40 . The MFP main body  30  performs printing on a recording medium, such as a sheet of paper. The option print control apparatus  40  is connected to the MFP main body  30  as an optional apparatus in order to improve a print function with the MFP main body  30 . The MFP main body  30  is capable of performing printing even in a single state in which the option print control apparatus  40  is not connected to the MFP main body  30 . 
       FIG. 3  shows a block diagram illustrating a configuration of the MFP main body  30 . 
     Referring to  FIG. 3 , the MFP main body  30  includes an operation unit  31 , a display unit  32 , a print engine  33 , a scanner  34 , a facsimile communication unit  35 , a network communication unit  36 , an option print control apparatus communication unit  37 , a storage unit  38 , and a control unit  39 . The operation unit  31  is an input device, such as buttons, with which various operations are inputted by a user. The display unit  32  is a display, such as a liquid crystal display (“LCD”), which displays a variety of information. The print engine  33  is a printer that prints on a recording medium. The scanner  34  is a scanning device that scans an image of a document. The facsimile communication unit  35  performs facsimile communication with an external facsimile apparatus (not illustrated) via a communication line, such as a public telephone circuit. The network communication unit  36  performs communication with an external apparatus via the network  11 . The option print control apparatus communication unit  37  performs communication with the option print control apparatus  40 . The storage unit  38  is a storage device, such as an electrically erasable and programmable read only memory (“EEPROM”) or a hard disk drive (“HDD”), capable of storing a variety of information. The control unit  39  controls the entire MFP main body  30 . 
     The operation unit  31  may include an input device that comprises a touch panel with the display unit  32 . 
     The storage unit  38  stores an image forming apparatus program  38 A and job information  38 B. The image forming apparatus program  38 A is executed by the MFP main body  30 . The job information  38 B relates to a print job used for the printing with the print engine  33 . 
     The image forming apparatus program  38 A may be installed in the MFP main body  30  during the manufacturing process of the MFP main body  30 , may be additionally installed in the MFP main body  30  from a storage medium, such as a secure digital (“SD”) card or a universal serial bus (“USB”) memory, or may be additionally installed in the MFP main body  30  from the network  11 . 
       FIG. 4  illustrates an example of the job information  38 B. 
     Referring to  FIG. 4 , the job information  38 B associates a job identifier (“ID”) serving as job identification information, which is identification information about a print job, with job type information. The job type information indicates whether the print job is for an MFP print system  39 B described below or an option print system  43 A described below. 
     For example, in the job information  38 B illustrated in  FIG. 4 , the job type information about a print job, the job ID of which is “Job001”, is an “MFP print system print job.” The job type information about a print job, the job ID of which is “Job002”, is an option print system print job.” 
     The control unit  39  illustrated in  FIG. 3  includes, for example, a central processing unit (“CPU”), a read only memory (“ROM”), and a random access memory (“RAM”). The CPU executes a program stored in the ROM or the storage unit  38 . The ROM stores programs and a variety of data in advance. The RAM is used as a working area of the CPU. 
     The control unit  39  functions as a job manager  39 A, the MFP print system  39 B, an arbitrator  39 C, and an engine interface  39 D. The job manager  39 A executes the image forming apparatus program  38 A stored in the storage unit  38  to function as a job issuing unit that issues a print job. The MFP print system  39 B controls the print engine  33  in accordance with the print job issued by the job manager  39 A. The arbitrator allocates the print job issued by the job manager  39 A to an appropriate print control unit, among the MFP print system  39 B and the option print system  43 A described below. The engine interface controls the communication with the print engine  33 . 
     The MFP print system  39 B performs a drawing process corresponding to the print job. The MFP print system  39 B is capable of instructing the print engine  33  to perform post-process, such as punching or stapling, in accordance with the print job. 
       FIG. 5  shows a block diagram illustrating a configuration of the option print control apparatus  40 . 
     Referring to  FIG. 5 , the option print control apparatus  40  includes an MFP communication unit  41 , a storage unit  42 , and a control unit  43 . The MFP communication unit  41  performs communication with the MFP main body  30  (refer to  FIG. 3 ). The storage unit  42  is a storage device, such as an EEPROM or an HDD, capable of storing a variety of information. The control unit  43  controls the entire option print control apparatus  40 . 
     The storage unit  42  stores an option print control apparatus program  42 A executed by the option print control apparatus  40 . 
     The control unit  43  includes, for example, a CPU, a ROM that stores programs and a variety of data in advance, and a RAM used as the working area of the CPU. The CPU executes a program stored in the ROM or the storage unit  42 . 
     The control unit  43  executes the option print control apparatus program  42 A stored in the storage unit  42  to function as the option print system  43 A, which is a print control unit controlling the print engine  33  in the MFP main body  30  in accordance with the print job issued by the job manager  39 A in the MFP main body  30 . 
     The option print system  43 A performs the drawing process corresponding to the print job. The option print system  43 A is capable of instructing the print engine  33  to perform the post-process, such as the punching or the stapling, in accordance with the print job. 
     The MFP print system  39 B in the MFP main body  30  differs from the option print system  43 A in the option print control apparatus  40  in at least part of the content of control capable of being performed for the print engine  33 . For example, the MFP print system  39 B is only capable of setting the stapling for one print job, while the option print system  43 A is capable of setting the stapling for a collection of recording media of an arbitrary number on which the printing is continuously performed in one print job. 
     The MFP print system  39 B in the MFP main body  30  operates separately from the option print system  43 A in the option print control apparatus  40 . In other words, the MFP print system  39 B in the MFP main body  30  and the option print system  43 A in the option print control apparatus  40  operate at specific timings. 
       FIG. 6  shows a block diagram illustrating a configuration of the computer  60 . 
     Referring to  FIG. 6 , the computer  60  includes an operation unit  61 , a display unit  62 , a network communication unit  63 , a storage unit  64 , and a control unit  65 . The operation unit  61  includes input devices, such as a keyboard and a mouse, with which various operations are input by a user. The display unit  62  is a display, such as a liquid crystal display (“LCD”), which displays a variety of information. The network communication unit  63  performs communication with an external apparatus via the network  11 . The storage unit  64  is a storage device, such as a hard disk drive (“HDD”), capable of storing a variety of information. The control unit  65  controls the entire computer  60 . 
     The storage unit  64  stores an MFP printer driver  64 A, which is a program causing the MFP main body  30  alone in the MFP  20  to perform printing on a recording medium, and a print control apparatus printer driver  64 B, which is a program causing the MFP main body  30  and the option print control apparatus  40  in the MFP  20  to cooperatively perform printing on a recording medium. 
     The MFP printer driver  64 A and the print control apparatus printer driver  64 B may be installed in the computer  60  in a manufacturing process of the computer  60 , may be additionally installed in the computer  60  from a storage medium, such as a compact disc (“CD”), a digital versatile disk (“DVD”), or a USB memory, or may be additionally installed in the computer  60  from the network  11 . 
     The control unit  65  includes, for example, a CPU, a ROM that stores programs and a variety of data in advance, and a RAM used as the working area of the CPU. The CPU executes a program stored in the ROM or the storage unit  64 . 
     An operations of the network system  10  will be described. 
     A flow of a print job in the MFP  20  will now be described. 
     The control unit  39  in the MFP main body  30  scans an image of a document with the scanner  34  upon receiving a copy instruction via the operation unit  31 . The control unit  39  requests the job manager  39 A to execute the print job based on the image scanned by the scanner  34 . The control unit  39  adds a job ID to the print job and, then, associates the job ID with information indicating the “MFP print system print job”, which is the job type information about the print job, to store the job ID associated with the above information in the job information  38 B in the storage unit  38 . 
     The control unit  39  in the MFP main body  30  requests the job manager  39 A to execute the print job based on FAX data upon receiving the FAX data transmitted from an external facsimile apparatus via the facsimile communication unit  35 . The control unit  39  adds a job ID to the print job and, then, associates the job ID with the information indicating the “MFP print system print job”, which is the job type information, to store the job ID associated with the above information in the job information  38 B in the storage unit  38 . 
     The control unit  39  in the MFP main body  30  requests the job manager  39 A to execute the print job based on print data upon receipt via the network communication unit  36  of the print data transmitted from the MFP printer driver  64 A in the computer  60  via the network communication unit  63 . The control unit  39  adds a job ID to the print job and, then, associates the job ID with the information indicating the “MFP print system print job”, which is the job type information, to store the job ID associated with the above information in the job information  38 B in the storage unit  38 . 
     The control unit  39  in the MFP main body  30  requests the job manager  39 A to execute the print job based on print data upon receipt via the network communication unit  36  of the print data transmitted from print control apparatus printer driver  64 B in the computer  60  via the network communication unit  63 . The control unit  39  adds a job ID to the print job and, then, associates the job ID with information indicating the “option print system print job”, which is the job type information about the print job, to store the job ID associated with the above information in the job information  38 B in the storage unit  38 . 
       FIG. 7  illustrates a flow of a print job in the MFP  20 . 
     Referring to  FIG. 7 , in Step S 101 , the job manager  39 A notifies the arbitrator  39 C of the print jobs the execution of which is requested in the execution requested order. In other words, the job manager  39 A issues the print jobs the execution of which is requested in the execution requested order. 
     If the print job notified by the job manager  39 A in Step S 101  is for the MFP print system  39 B, in Step S 102 A, the arbitrator  39 C notifies the MFP print system  39 B of the print job. 
     The MFP print system  39 B performs, for example, the drawing process corresponding to the print job notified by the arbitrator  39 C in Step S 102 A. In Step S 103 A, the MFP print system  39 B generates pieces of data, which the print engine  33  is to be notified of for every page in the print job, and sequentially notifies the engine interface  39 D of the data for every page. 
     In Step S 104 , the engine interface  39 D sequentially notifies the print engine  33  of the pieces of data for every page notified by the MFP print system  39 B in Step S 103 A. 
     After the print engine  33  sequentially performs the printing on recording media based on the data for every page notified by the engine interface  39 D in Step S 104 , in Step S 105 , the print engine  33  sequentially notifies the engine interface  39 D of completion of the printing for every page. 
     In Step S 106 A, the engine interface  39 D sequentially notifies the MFP print system  39 B of the completion of the printing for every page, notified by the print engine  33  in Step S 105 . 
     If the MFP print system  39 B determines that the MFP print system  39 B is notified of the completion of the printing of all the pages in the print job by the engine interface  39 D, based on the completion of the printing for every page notified by the engine interface  39 D in Step S 106 A, in Step S 107 A, the MFP print system  39 B notifies the arbitrator  39 C of the completion of the execution of the print job. 
     In Step S 108 , the arbitrator  39 C notifies the job manager  39 A of the completion of the execution of the print job notified by the MFP print system  39 B in Step S 107 A. 
     If the print job notified by the job manager  39 A in Step S 101  is for the option print system  43 A, in Step S 102 B, the arbitrator  39 C notifies the option print system  43 A of the print job. The print job which the option print system  43 A is notified of by the arbitrator  39 C is supplied from the arbitrator  39 C to the option print system  43 A sequentially via the option print control apparatus communication unit  37  in the MFP main body  30  and the MFP communication unit  41  in the option print control apparatus  40 . 
     The option print system  43 A performs, for example, the drawing process corresponding to the print job notified by the arbitrator  39 C in Step S 102 B. In Step S 103 B, the option print system  43 A generates pieces of data which the print engine  33  is to be notified of for every page in the print job and sequentially notifies the engine interface  39 D of the generated data for every page. The data which the engine interface  39 D is notified of by the option print system  43 A is supplied from the option print system  43 A to the engine interface  39 D sequentially via the MFP communication unit  41  in the option print control apparatus  40  and the option print control apparatus communication unit  37  in the MFP main body  30 . 
     In Step S 104 , the engine interface  39 D sequentially notifies the print engine  33  of the pieces of data for every page notified by the option print system  43 A in Step S 103 B. 
     After the print engine  33  sequentially performs printing on the recording media based on the data for every page notified by the engine interface  39 D in Step S 104 , in Step S 105 , the print engine  33  sequentially notifies the engine interface  39 D of completion of the printing for every page. 
     In Step S 106 B, the engine interface  39 D sequentially notifies the option print system  43 A of the completion of the printing for every page, notified by the print engine  33  in Step S 105 . 
     If the option print system  43 A determines that the option print system  43 A is notified of the completion of the printing of all the pages in the print job by the engine interface  39 D, based on the completion of the printing for every page notified by the engine interface  39 D in Step S 106 B, in Step S 107 B, the option print system  43 A notifies the arbitrator  39 C of the completion of the execution of the print job. 
     In Step S 108 , the arbitrator  39 C notifies the job manager  39 A of the completion of the execution of the print job notified by the option print system  43 A in Step S 107 B. 
     Operations of the arbitrator  39 C will be described. 
     An operation of the arbitrator  39 C, when the arbitrator  39 C is notified of a new print job by the job manager  39 A, will now be described. 
       FIG. 8  shows a flowchart illustrating an operation of the arbitrator  39 C when the arbitrator  39 C is notified of a new print job by the job manager  39 A. When the arbitrator  39 C is notified of a new print job by the job manager  39 A, the arbitrator  39 C performs the operation illustrated in  FIG. 8 . 
     Referring to  FIG. 8 , in Step S 131 , the arbitrator  39 C adds data about the new print job notified by the job manager  39 A to a queue. Such a print job is hereinafter referred to as a “current print job.” 
       FIG. 9A  illustrates an example of a queue managed by the arbitrator  39 C.  FIG. 9B  illustrates another example of a queue managed by the arbitrator  39 C, which is different from the example of a queue illustrated in  FIG. 9A .  FIG. 9C  illustrates another example of a queue managed by the arbitrator  39 C, which is different from the example of queues illustrated in  FIG. 9A  and  FIG. 9B . 
     Multiple pieces of data are recorded in each of the queues illustrated in  FIG. 9A ,  FIG. 9B , and  FIG. 9C . In each piece of data, the job ID of a print job, the job type of the print job, and the state of the print job are associated with each other. The pieces of data having lower orders are input into the queue earlier. Although only the pieces of data about three print jobs are included in each of the queues in  FIG. 9A ,  FIG. 9B , and  FIG. 9C , the pieces of data about print jobs of a number greater than three may be included in each queue. 
     Upon notification of the job ID of the print job by the job manager  39 A, the arbitrator  39 C acquires the job type of the print job based on the job information  38 B in the storage unit  38 . 
     Referring back to  FIG. 8 , in Step S 132 , the arbitrator  39 C determines whether allocation of a print job notified by the job manager  39 A immediately before the current print job (such a print job is hereinafter referred to as a “next previous print job of the current print job”) to either of the MFP print system  39 B and the option print system  43 A is placed on standby. 
     For example, when the queue including the data about the current print job is in the state illustrated in  FIG. 9A , the next previous print job of the current print job (the print job the order of which is “3”), that is, the print job the order of which is “2” is in a “standby state.” Accordingly, the arbitrator  39 C determines in Step S 132  that allocation of the next previous print job of the current print job to either of the MFP print system  39 B and the option print system  43 A is placed on standby. 
     In contrast, when the queue including the data about the current print job is in the state illustrated in  FIG. 9B  or  FIG. 9C , the next previous print job of the current print job (the print job the order of which is “3”), that is, the print job the order of which is “2” is in an “allocated state.” Accordingly, the arbitrator  39 C determines in Step S 132  that allocation of the next previous print job of the current print job to either of the MFP print system  39 B and the option print system  43 A is not placed on standby. 
     Also when no next previous print job of the current print job exists, the arbitrator  39 C determines in Step S 132  that allocation of the next previous print job of the current print job to either of the MFP print system  39 B and the option print system  43 A is not placed on standby. 
     If the arbitrator  39 C determines in Step S 132  that allocation of the next previous print job of the current print job to either of the MFP print system  39 B and the option print system  43 A is placed on standby, in Strep S 133 , the arbitrator  39 C places allocation of the current print job to either of the MFP print system  39 B and the option print system  43 A on standby. In other words, the arbitrator  39 C sets the current print job to the “standby state.” For example, when the queue including the data about the current print job is in the state illustrated in  FIG. 9A , the arbitrator  39 C sets the current print job, that is, the print job the order of which is “3” to the “standby state” in Step S 133 . Upon completion of the process in Step S 133 , the operation illustrated in  FIG. 8  is terminated. 
     If the arbitrator  39 C determines in Step S 132  that allocation of the next previous print job of the current print job to either of the MFP print system  39 B and the option print system  43 A is not placed on standby, in Strep S 134 , the arbitrator  39 C determines whether the job type of the current print job is different from that of the next previous print job. 
     For example, when the queue including the data about the current print job is in the state illustrated in  FIG. 9B , the job type of the current print job (the print job the order of which is “3”), which is the “MFP print system print job”, is different from the job type of the next previous print job of the current print job (the print job the order of which is “2”), which is the “option print system print job.” Accordingly, the arbitrator  39 C determines in Step S 134  that the job type of the current print job is different from that of the next previous print job. 
     In contrast, when the queue including the data about the current print job is in the state illustrated in  FIG. 9C , the job type of the current print job (the print job the order of which is “3”), which is the “MFP print system print job”, is the same as the job type of the next previous print job of the current print job (the print job the order of which is “2”), which is the “MFP print system print job.” Accordingly, the arbitrator  39 C determines in Step S 134  that the job type of the current print job is the same as that of the next previous print job. 
     Also when no next previous print job of the current print job exists, the arbitrator  39 C determines in Step S 134  that the job type of the current print job is the same as that of the next previous print job. 
     If the arbitrator  39 C determines in Step S 134  that the job type of the current print job is different from that of the next previous print job, in Step S 133 , the arbitrator  39 C places allocation of the current print job to either of the MFP print system  39 B and the option print system  43 A on standby. In other words, the arbitrator  39 C sets the current print job to the “standby state.” For example, when the queue including the data about the current print job is in the state illustrated in  FIG. 9B , the arbitrator  39 C sets the current print job, that is, the print job the order of which is “3” to the “standby state” in Step S 133 . Upon completion of the process in Step S 133 , the operation illustrated in  FIG. 8  is terminated. 
     If the arbitrator  39 C determines in Step S 134  that the job type of the current print job is not different from that of the next previous print job, that is, the job type of the current print job is the same as that of the next previous print job, in Step S 135 , the arbitrator  39 C allocates the current print job to an appropriate print system, among the MFP print system  39 B and the option print system  43 A. Specifically, the arbitrator  39 C allocates the current print job to the MFP print system  39 B (Step S 102 A) if the job type of the current print job is the “MFP print system print job” and allocates the current print job to the option print system  43 A (Step S 102 B) if the job type of the current print job is the “option print system print job.” 
     In Step S 136 , the arbitrator  39 C sets the current print job to the “allocated state.” 
     For example, when the queue including the data about the current print job is in the state illustrated in  FIG. 9C , the arbitrator  39 C allocates the current print job, that is, the print job the order of which is “3” to the MFP print system  39 B in Step S 135  and, then, sets the print job to the “allocated state” in Step S 136 . Upon completion of the process in Step S 136 , the operation illustrated in  FIG. 8  is terminated. 
     An operation of the arbitrator  39 C when the arbitrator  39 C is notified of completion of execution of a print job by a print system will now be described. 
       FIG. 10  shows a flowchart illustrating operation of the arbitrator  39 C when the arbitrator  39 C is notified of completion of execution of a print job by a print system. When the arbitrator  39 C is notified of completion of execution of a print job by a print system, the arbitrator  39 C performs the operation illustrated in  FIG. 10 . 
     Referring to  FIG. 10 , in Step S 161 , the arbitrator  39 C deletes the data about the print job, the completion of the execution of which is notified by a print system, that is, either of the MFP print system  39 B and the option print system  43 A from the queue. Specifically, the arbitrator  39 C deletes the data about the oldest print job in the queue. 
     In Step S 162 , the arbitrator  39 C determines whether the data about the print job remains in the queue. 
     If the arbitrator  39 C determines in Step S 162  that no data about the print job remains in the queue, in Step S 108 , the arbitrator  39 C notifies the job manager  39 A of the completion of the execution of the print job notified by the print system. Then, the operation illustrated in  FIG. 10  is terminated. 
     If the arbitrator  39 C determines in Step S 162  that the data about the print job remains in the queue, in Step S 163 , the arbitrator  39 C determines whether allocation of the oldest print job to either of the MFP print system  39 B and the option print system  43 A is placed on standby, as in Step S 132 . 
     For example, when the queue immediately before the process in Step S 161  is in the state illustrated in  FIG. 9A , the oldest print job in Step S 163  is the print job the order of which is “2” in  FIG. 9A . Since the print job the order of which is “2” is in the “standby state”, the arbitrator  39 C determines in Step S 163  that allocation of the oldest print job to either of the MFP print system  39 B and the option print system  43 A is placed on standby. 
     In contrast, when the queue immediately before the process in Step S 161  is in the state illustrated in  FIG. 9B  or  FIG. 9C , the oldest print job in Step S 163  is the print job the order of which is “2” in  FIG. 9B  or  FIG. 9C . Since the print job the order of which is “2” is in the “allocated state”, the arbitrator  39 C determines in Step S 163  that allocation of the oldest print job to either of the MFP print system  39 B and the option print system  43 A is not placed on standby. 
     If the arbitrator  39 C determines in Step S 163  that allocation of the oldest print job to either of the MFP print system  39 B and the option print system  43 A is not placed on standby, in Step S 108 , the arbitrator  39 C notifies the job manager  39 A of the completion of the execution of the print job notified by the print system. Then, the operation illustrated in  FIG. 10  is terminated. 
     If the arbitrator  39 C determines in Step S 163  that allocation of the oldest print job to either of the MFP print system  39 B and the option print system  43 A is placed on standby, in Step S 164 , the arbitrator  39 C allocates the oldest print job to an appropriate print system, among the MFP print system  39 B and the option print system  43 A, as in Step S 135 . 
     In Step S 165 , the arbitrator  39 C sets the oldest print job to the “allocated state”, as in Step S 136 . 
     For example, when the queue immediately before the process in Step S 161  is in the state illustrated in  FIG. 9A , the oldest print job in Steps S 163  to S 165  is the print job the order of which is “2” in  FIG. 9A . The arbitrator  39 C allocates the print job the order of which is “2” to the option print system  43 A in Step S 164  and, then, sets the print job to the “allocated state” in Step S 165 . 
     In Step S 166 , the arbitrator  39 C determines whether the print job next to the target print job remains in the queue after the process in Step S 165 . For example, when the target print job immediately before the process in Step S 166  is the print job the order of which is “2” in  FIG. 9A , the arbitrator  39 C determines in Step S 166  that the print job next to the print job the order of which is “2”, that is, the print job the order of which is “3” in  FIG. 9A  remains in the queue. 
     If the arbitrator  39 C determines in Step S 166  that the print job next to the target print job does not remain in the queue, in Step S 108 , the arbitrator  39 C notifies the job manager  39 A of the completion of the execution of the print job notified by the print system. Then, the operation illustrated in  FIG. 10  is terminated. 
     If the arbitrator  39 C determines in Step S 166  that the print job next to the target print job remains in the queue, in Step S 167 , the arbitrator  39 C determines whether the job type of the next print job is different from that of the last print job, as in Step S 134 . 
     For example, when the “last print job” and the “next print job” in Step S 167  are the print job the order of which is “2” and the print job the order of which is “3”, respectively, in  FIG. 9A , the arbitrator  39 C determines in Step S 167  that the job type of the next print job is different from that of the last print job. 
     If the arbitrator  39 C determines in Step S 167  that the job type of the next print job is different from that of the last print job, in Step S 108 , the arbitrator  39 C notifies the job manager  39 A of the completion of the execution of the print job notified by the print system. Then, the operation illustrated in  FIG. 10  is terminated. 
     If the arbitrator  39 C determines in Step S 167  that the job type of the next print job is not different from that of the last print job, in Step S 168 , the arbitrator  39 C allocates the next print job to an appropriate print system, among the MFP print system  39 B and the option print system  43 A, as in Step S 135 . In Step S 169 , the arbitrator  39 C sets the next print job to the “allocated state”, as in Step S 136 . Then, the operation goes back to Step S 166 . 
     With the image forming apparatus of the present disclosure, it is possible for the MFP  20  to prevent the sequence of the printing based on the print job for the MFP print system  39 B and the printing based on the print job for the option print system  43 A from being inappropriately changed by, for example, inversion to be executed by the print engine  33 . As a result, it is possible to output the printout based on the print job for the MFP print system  39 B and the printout based on the print job for the option print system  43 A in an appropriate sequence. 
     Since the content of control capable of being executed for the print engine  33  by the MFP print system  39 B is at least partially different from that for the print engine  33  by the option print system  43 A in the MFP  20 , the process time of the print job capable of being processed only by the MFP print system  39 B by the MFP print system  39 B may be significantly different from the process time of the print job capable of being processed only by the option print system  43 A by the option print system  43 A. In addition, since the MFP print system  39 B and the option print system  43 A are achieved by different pieces of hardware: the control unit  39  and the control unit  43 , respectively, in the MFP  20 , the process time of the print job allocated to the MFP print system  39 B by the MFP print system  39 B may be different from the process time of the print job allocated to the option print system  43 A by the option print system  43 A. However, it is possible for the MFP  20  to prevent the sequence of the printing based on the print job for the MFP print system  39 B and the printing based on the print job for the option print system  43 A from being inappropriately changed to be executed by the print engine  33 . Accordingly, it is possible to output the printout based on the print job for the MFP print system  39 B and the printout based on the print job for the MFP print system  39 B in an appropriate sequence. 
     With the image forming apparatus of the present disclosure, after the MFP  20  allocates the last print job issued by the job manager  39 A to the MFP print system  39 B, the MFP  20  allocates the next print job issued by the job manager  39 A to the MFP print system  39 B even if the control by the print engine  33  corresponding to the last print job is not terminated. Accordingly, it is possible for the MFP  20  to reduce the time required for the printing based on the multiple continuous print jobs for the MFP print system  39 B, compared with a configuration in which the allocation of the next print job issued by the job manager  39 A to the MFP print system  39 B is placed on standby when the control by the print engine  33  corresponding to the last print job is not terminated after the MFP  20  allocates the last print job issued by the job manager  39 A to the MFP print system  39 B. 
     Similarly, with the image forming apparatus of the present disclosure, after the MFP  20  allocates the last print job issued by the job manager  39 A to the option print system  43 A, the MFP  20  allocates the next print job issued by the job manager  39 A to the option print system  43 A even if the control by the print engine  33  corresponding to the last print job is not terminated. Accordingly, it is possible for the MFP  20  to reduce the time required for the printing based on the multiple continuous print jobs for the option print system  43 A, compared with a configuration in which the allocation of the next print job issued by the job manager  39 A to the option print system  43 A is placed on standby when the control by the print engine  33  corresponding to the last print job is not terminated after the MFP  20  allocates the last print job issued by the job manager  39 A to the option print system  43 A. 
     Although the image forming apparatus of the present disclosure is the MFP in the above embodiments, an image forming apparatus other than the MFP, such as a printer machine, may be adopted. 
     It should be understood that various changes and modifications to the presently preferred embodiments described herein will be apparent to those skilled in the art. Such changes and modifications can be made without departing from the spirit and scope of the present subject matter and without diminishing its intended advantages. It is therefore intended that such changes and modifications be covered by the appended claims.