Patent Publication Number: US-8970872-B2

Title: Image formation control apparatus, image formation apparatus, image formation system, computer readable medium, and tandem printing system

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is based upon and claims priority under 35 USC 119 from Japanese Patent Application No. 2010-050310, filed Mar. 8, 2010. 
     BACKGROUND 
     Technical Field 
     The present invention relates to an image formation control apparatus, an image formation apparatus, an image formation system, a computer readable medium, and a tandem printing system. 
     SUMMARY OF THE INVENTION 
     According to an aspect of the invention, an image formation control apparatus includes an image formation processing management unit, a communication unit, and a control unit. The image formation processing management unit manages first image formation processing on a first face of a planar recording medium. The first image formation processing is performed by a first image formation apparatus. The communication unit communicates with a second image forming apparatus configured to perform image formation on a second face of the planar recording medium. The second face is an opposing face with respect to the first face. A type of the first image formation apparatus is different from a type of the second image formation apparatus. The control unit performs control of transportation of the planar recording medium from the first image formation apparatus to the second image formation apparatus or from the second image formation apparatus. A first amount of time to start image formation from receiving an image formation instruction in the first image formation apparatus is smaller that a second amount of time to start image formation from receiving an image formation instruction in the second image formation apparatus. When an instruction to start image formation on the planar recording medium is issued, the control unit controls the transportation of the planar recording medium to transport the recording medium for a given time longer than the second amount of time without image forming on the planar recording medium. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Exemplary embodiments of the invention will be described in detail based on the following figures, wherein: 
         FIG. 1  is a perspective view showing a tandem printing system of an exemplary embodiment; 
         FIG. 2  is a conceptual view showing the tandem printing system of the exemplary embodiment; 
         FIG. 3  is a block diagram of a control system of the exemplary embodiment; 
         FIGS. 4A to 4C  are principle views explaining a principle of a displacement of images when duplex printing is performed; 
         FIGS. 5A to 5C  are principle views showing a principle of the exemplary embodiment; 
         FIG. 6  is a flow chart showing an example of procedures of an operation of the exemplary embodiment; 
         FIG. 7  is a flow chart showing an example of procedures of an operation of the exemplary embodiment; 
         FIG. 8  is a flow chart showing an example of procedures of an operation of the exemplary embodiment; 
         FIG. 9  is a flow chart showing an example of procedures of an operation of the exemplary embodiment; 
         FIG. 10  is a flow chart showing an example of procedures of an operation of the exemplary embodiment; and 
         FIGS. 11A and 11B  are principle views showing a principle of the exemplary embodiment. 
     
    
    
     DETAILED DESCRIPTION 
     Overall Configuration 
     A description will be given hereinbelow of an example in which the present invention is utilized.  FIG. 1  shows an example of a tandem printing system in which the present invention is utilized.  FIG. 2  shows a block diagram of the system in  FIG. 1 . Each of  FIGS. 1 and 2  shows a tandem printing system  10 . The tandem printing system  10  has a function of performing image formation on front and back sides (faces) of continuous paper as an example of a planar recording medium by utilizing image formation apparatuses  12  and  14 . 
     First, the image formation apparatus  12  is disposed on the upstream side in terms of a transport path of the paper. The image formation apparatus  12  is a monochrome printer for forming a single color image (a black-and-white image in this case), and externally includes a roll paper feeding apparatus  31  that feeds the continuous paper wound in a roll shape. On the downstream side of the roll paper feeding apparatus  31 , there is disposed a transfer unit  32  that transfers a toner image to a continuous paper P sent out from the roll paper feeding apparatus  31 . The transfer unit  32  includes a photosensitive drum  33 . The photosensitive drum  33  is irradiated with an image-drawing laser beam from an exposure apparatus that is not shown, and an electrostatic latent image is thereby formed. The electrostatic latent image is developed using a black toner by a development apparatus that is not shown, and a monochrome toner image is thereby formed. The toner image is transferred to the continuous paper P. 
     On the downstream side of the transfer unit  32 , a fixing apparatus  34  is disposed. The fixing apparatus  34  irradiates the toner image on the continuous paper P with strong light to fix it onto the continuous paper P. The image formation apparatus  12  includes a control apparatus  35 . The control apparatus  35  controls an operation of the image formation apparatus  12 . The detail of the control apparatus  35  will be described later. 
     The image formation apparatus  12  forms a positioning mark that will be described later on the continuous paper P. The positioning mark is read by the image formation apparatus  14  on the downstream side, and is used for positioning when image formation with respect to the back side of the continuous paper P is performed in the image formation apparatus  14 . 
     The image formation apparatus  12  includes a manipulation panel  20 . The manipulation panel  20  is a touch panel display, and is used for various manipulations by an operator. In addition, the manipulation panel  20  displays various information items for the operator. 
     The paper P formed with an image on one side in the image formation apparatus  12  is sent to a buffer apparatus  18 . The buffer apparatus  18  has a function of bending the continuous paper P during transport inside the buffer apparatus  18  to eliminate looseness, a twist, a flutter, and an excessive tension of the continuous paper P. 
     On the downstream side of the buffer apparatus  18 , a side reversing apparatus  16  is disposed. The side reversing apparatus  16  reverses the front and back sides (upper and under sides) of the continuous paper P, and sends the paper P to the image formation apparatus  14  on the downstream side. 
     The continuous paper P of which the front and back sides are reversed by the side reversing apparatus  16  is sent to the image formation apparatus  14  where the image formation is performed with respect to a side opposite to the side formed with the image by the image formation apparatus  12 . Herein, the image formation apparatus  14  is configured to be capable of color image formation. 
     The image formation apparatus  14  includes an optical sensor  41 . The optical sensor  14  optically detects the positioning mark formed on the continuous paper P in the image formation apparatus  12 . On the downstream side of the optical sensor  41 , a transfer unit  42  is disposed. The transfer unit  42  includes photosensitive drums  43 ,  44 ,  45 , and  46  for forming toner images of basic colors of YMCK. The configuration of each of the photosensitive drums  43 ,  44 ,  45 , and  46  is the same as that of the photosensitive drum  33  in the image formation apparatus  12  except the toner colors to be used. 
     In the transfer unit  42 , toner images are formed on the side opposite to the side formed with the image in the image formation apparatus  12 . On the downstream side of the transfer unit  42 , a fixing apparatus  47  is disposed. Similarly to the fixing apparatus  34 , the fixing apparatus  47  irradiates toner images on the continuous paper P with strong light to fix them onto the continuous paper P. On the downstream side of the fixing apparatus  47 , there is externally disposed a paper winding apparatus  48  that winds up the continuous paper P formed with the images on both sides. 
     The image formation apparatus  14  includes a control apparatus  49 . The control apparatus  49  controls an operation of the image formation apparatus  14 . The detail of the control apparatus  14  will be described later. The image formation apparatus  14  includes a manipulation panel  21 . The manipulation panel  21  is a touch panel display, and is used for various manipulations by the operator. In addition, the manipulation panel  21  displays various information items for the operator. 
     The tandem printing system  10  includes a host terminal  50 . The host terminal  50  is a terminal that performs manipulations related to the operation of the tandem printing system  10 . It is also possible to manipulate the tandem printing system  10  using the manipulation panel  20  or  21  without disposing the host terminal. 
     In the above-described tandem printing system  10 , there is used the positioning mark that functions as a mark in order to match the positions of the images on the front and back sides when printing is performed with respect to both sides of the continuous paper P. Specifically, the positioning mark is formed in the image formation apparatus  12 , the positioning mark is optically detected by the optical sensor  41  in the image formation apparatus  14  in the image formation with respect to the back side in the image formation apparatus  14 , and, on the basis of the detected positioning mark, the image formation with respect to the second side that corresponds to the position of the image formed on the first side is performed in the image formation apparatus  14 . The positioning mark is formed in an inconspicuous area close to the edge of the continuous paper or the like. 
     (Configuration of Control System) 
       FIG. 3  shows a control system of each of the image formation apparatuses  12  and  14 . Herein, the image formation apparatus  12  is only for monochrome printing, while the image formation apparatus  14  is capable of color printing. However, when considered as control blocks, they have the same basic configuration. 
     Each of the control apparatuses  35  and  49  is an apparatus functioning as a computer, and includes a CPU  61 , a panel I/F section  62 , a HDD  63 , an engine I/F section  64 , a ROM  66 , a RAM  67 , and a communication I/F section  68 . The CPU  61  is a device that exercises control over the operation of the control apparatus  35  ( 49 ), and executes a flow chart described later. In addition, the function of the CPU  61  allows various processing related to an image formation operation to be performed. The panel I/F section  62  is an interface apparatus that connects between the manipulation panel  20  ( 21 ) and the control apparatus  35  ( 49 ). The HDD  63  is a hard disk apparatus that stores various information items. 
     The engine I/F section  64  is an interface apparatus that intervenes between a printer mechanism section  65  and the control apparatus  35  ( 49 ). The printer mechanism section  65  corresponds to a mechanism portion for performing the image formation operation inside the image formation apparatus  12  ( 14 ) and a mechanism portion related to the transport of the continuous paper. The image formation apparatus  12  is a monochrome printer, while the image formation apparatus  14  is a color printer. Due to this difference, the printer mechanism sections  65  and  65  of the image formation apparatuses  12  and  14  have different configurations, though the depiction thereof is omitted. 
     The ROM  66  stores programs for performing operations described later and various set items. The RAM  67  functions as a memory area that temporarily stores image data of an image to be formed and various data. The communication I/F section  68  is an interface apparatus for performing communication with the outside of the apparatus. For example, the communication I/F section  68  functions as a communication apparatus when the image formation apparatus  12  communicates with the image formation apparatus  14  via the host terminal  50 . 
     In addition, in terms of its function, the control apparatus  35  of the image formation apparatus  12  is considered to have a configuration that includes an image formation processing management section  71 , a communication section  72 , and a control section  73 . The image formation processing management section  71  manages image formation processing with respect to the first side of the continuous paper P. The communication section  72  performs communication with the image formation apparatus  14  on the downstream side that has a type different from that of the image formation apparatus  12 , and performs image formation with respect to the second side of the continuous paper P. 
     The control section  73  performs control (control of blank paper sending described later) of sending out the continuous paper P to the image formation apparatus  14  without performing the image formation processing with respect to the first side during a time period not less than a time period from a time when the continuous paper P reaches the image formation apparatus  14  on the downstream side to a time when the image formation with respect to the second side in the image formation apparatus  14  is performed (i.e., a time period when registration processing described layer is performed). 
     (Operation Principle) 
     A description will be given hereinbelow of an operation principle of the tandem printing, system  10  shown in  FIG. 1 .  FIGS. 4A to 4C  conceptually show the tandem printing system  10 . Herein, consideration is given to the case where the image formation with respect to the first side of the continuous paper P is performed in the image formation apparatus  12 , and the image formation with respect to the second side thereof is performed in the image formation apparatus  14 . It is assumed herein that the image formation apparatus  14  needs processing in which the continuous paper P equivalent to three sheets of a given standard size is firstly transported in the apparatus, and a function of matching formation positions of images of four colors of YMCK is initialized during the transport in order to perform image formation using four photosensitive drums. 
     The processing will be described hereinbelow. The image formation apparatus  14  includes the four photosensitive drums  43  to  46 , as shown in  FIG. 2 . Individual toner images of YMCK are formed on the individual photosensitive drums, and transferred to the continuous paper P, whereby a color image is formed. In the processing, it is necessary to superimpose the toner images of YMCK with high precision. Accordingly, processing for adjusting the transfer position on the continuous paper P with respect to the portions of the individual photosensitive drums is performed. In this processing, the continuous paper P is transported in the image formation apparatus  14 , the images of YMCK are actually formed and superimposed on an edge of the continuous paper P or the like, the image is detected using an optical sensor (the depiction thereof is omitted), and the state of superimposing of the individual colors is determined. On the basis of the determination, timing for forming the individual images of YMCK or the like is adjusted, and adjustment is thereby performed such that the images of YMCK are superimposed with high precision. In the description below, the procedure for this adjustment is referred to as “registration”. 
     On the basis of the above-described assumption, a description will be given firstly of the case where the present invention is not utilized. In this case, in the state where the continuous paper P is being transported in a direction from the image formation apparatus  12  toward the image formation apparatus  14 , the formation of the image and the positioning mark on one side of the continuous paper P is performed in the image formation apparatus  12 . Subsequently, at the stage where the leading end of the continuous paper P reaches the image formation apparatus  14 , the registration processing of the image formation position in the image formation apparatus  14  is started. This state is shown in  FIG. 4A . 
     As described above, in this case, in order to complete the registration processing in the image formation apparatus  14 , it is necessary to move the continuous paper P equivalent to three sheets of a given standard size from the start of the processing. Consequently, as shown in  FIG. 4B , at the stage where the continuous paper P formed with the image on one side by the image formation apparatus  12  has further moved (passed) by the distance equivalent to the three sheets, the image formation with respect to the other side in the image formation apparatus  14  is started. Accordingly, in the operation form described above, the images on one side and the other side are displaced from each other by three sheets of the given standard size. This state is shown in  FIG. 4C . 
     Next, a description will be given of an example of an operation form (an example of an operation form of the present invention) that eliminates the inconvenience of which the principle is shown in  FIGS. 4A to 4C .  FIGS. 5A to 5C  are principle views explaining a principle of the example of the operation form of the present invention. In this case, blank paper sending equivalent to three sheets of the given standard size is performed at the point of time when the transport of the continuous paper P is started in the image formation apparatus  12  and, thereafter, the image formation is started from the fourth sheet. The blank paper sending mentioned herein means processing in which the continuous paper P is transported toward the downstream side in the state where the image formation is not performed, and only the formation of the positioning mark is performed with respect to the continuous paper P. 
     With the processing shown in  FIGS. 5A to 5C , the continuous paper P having been subjected to the blank paper sending described above passes through the image formation apparatus  14  during the time period when the registration processing in the image formation apparatus  14  is performed, and the image formation with respect to the second side in the image formation apparatus  14  is started from the fourth sheet after the blank paper sending. Specifically, an operation is realized in which, during the time period when the registration processing in the image formation apparatus  14  is performed, a portion of the continuous paper formed with the image on the first side does not reach the position of the transfer unit  42  in the image formation apparatus  14 . 
     In this case, as described above, the image formation apparatus  12  is set such that the image formation is also started from the fourth sheet so that it is possible to match the positions of the images on the front and back sides of the continuous paper P. This state is conceptually shown in  FIG. 5C . 
     Operation Example 1 
     An example of the specific operation will be described hereinbelow.  FIG. 6  shows an example of procedures of the operation of the image formation apparatus  12  disposed on the upstream side. The processing in  FIG. 6  is performed by executing a program stored in the image formation apparatus  12  by the control apparatus  35  in the image formation apparatus  12 . 
     When the power of the system is turned ON, the processing is started (step S 601 ). When the processing is started, it is determined whether or not image formation processing is to be started (step S 602 ). When it is determined that the image formation processing is to be started, the procedure advances to a step S 603  and, otherwise, the step S 602  is repeated. In the step S 603 , it is determined whether or not the image formation apparatus of concern (i.e., the image formation apparatus  12 ) is disposed on the upstream side in the tandem printing system  10  (step S 603 ). In the case shown in  FIG. 1 , the image formation apparatus  12  is disposed on the upstream side in the tandem printing system  10  so that the procedure advances to a step S 604 . When the image formation apparatus of concern is disposed on the downstream side in the tandem printing system, the procedure advances to a step S 607 . 
     In the step S 604 , it is determined whether or not the tandem printing system  10  is in a color mode (i.e., an operation mode including color image formation) (step S 604 ). In this example, color printing is performed in the image formation apparatus  14  on the downstream side so that the tandem printing system  10  is in the color mode, and the procedure advances to a step S 605 . When the image formation apparatus  14  on the downstream side performs monochrome printing, the tandem printing system  10  is not in the color mode so that the procedure advances to a step S 609 . 
     In the step S 605 , the processing of the blank paper sending is performed. The processing of the blank paper sending is processing in which the formation of the image to be printed is not performed, only the positioning mark is formed, and the continuous paper P is sent out toward the downstream side. 
     After the step S 605  is started, it is determined whether or not elapsed time of the sending out of the continuous paper P performed since the start of the procedure in the step S 605  is not less than time required for the registration processing in the image formation apparatus  14  (step S 606 ). In this processing, the elapsed time of execution of the sending out of the continuous paper P is converted into the number of sheets of the continuous paper P that are sent out during the elapsed time, and the number of sheet of the continuous paper P is used as one of parameters for comparison. In addition, the time required for the registration processing is converted into the number of sheets of the continuous paper P that pass an observation reference point, and the number of sheets of the continuous paper P is used as the other parameter for comparison. On the basis of these parameters, it is determined whether or not the number of transported sheets is not less than the number of sheets required for the registration in the image formation apparatus  14 . This processing may be performed by carrying out arithmetic calculation on the basis of a transport distance covered by the transported continuous paper P. 
     In the step S 606 , when the number of transported sheets after the start of the blank paper sending is not less than the number of sheets required for the registration in the image formation apparatus  14 , the procedure advances to the step S 609  and, otherwise, the processing of the blank paper sending in the step S 605  is continued. In the step S 609 , the image formation processing is started, and the image formation with respect to the first side by the image formation apparatus  12  is started. Subsequently, the transport of the continuous paper P is stopped (step S 611 ) at the stage where subsequent processing such as winding of the continuous paper P or the like is completed, and the processing is ended (step S 612 ). 
     In the case where the procedure advances from the step S 603  to the step S 607 , the positioning mark formed by the image formation apparatus disposed on the upstream side is read (step S 607 ) and, when the read positioning mark is on a sheet where the image is to be formed (a sheet of concern), the procedure advances to the step S 609 , and the image formation is performed (step S 609 ). When the read positioning mark is not on the sheet of concern due to the stoppage of sheet transport caused by paper jamming or the like, the procedure returns to the step S 607 , and the positioning mark is read again. 
     When the image formation apparatus of concern  12  is disposed on the downstream side in the tandem printing apparatus, reading of the positioning mark formed by the image formation apparatus on the upstream side is performed for each sheet, and the depiction of the processing is omitted in the flow chart in  FIG. 6 . 
     Next, a description will be given of an example of processing in the image formation apparatus  14  to be paired with the image formation apparatus  12 .  FIG. 7  shows the example of the processing performed in the image formation apparatus  14 . The processing in  FIG. 7  is performed by executing a program stored in the image formation apparatus  14  by the control apparatus  49  in the image formation apparatus  14 . 
     When the power of the system is turned ON, the processing is started (step S 701 ). When the processing is started, it is determined whether or not the image formation processing is to be started (step S 702 ). When it is determined that the image formation processing is to be started, the procedure advances to a step S 703  and, otherwise, the procedure in the step S 702  is repeated. 
     In the step S 703 , it is determined whether or not the image formation apparatus of concern (in this flow chart, the image formation apparatus  14 ) is disposed on the upstream side in the tandem printing system  10  (step S 703 ). In this example, the image formation apparatus of concern  14  is disposed on the downstream side so that the procedure advances to a step S 707 . In the step S 707 , it is determined whether or not the tandem printing system  10  operates in the color mode (i.e., the tandem printing system  10  is in a printing mode including the color image) (step S 707 ). When the color mode is set, the procedure advances to a step S 708  and, otherwise, the procedure advances to a step S 710 . 
     In the step S 708 , the registration processing is started and thereafter, it is determined whether or not the registration processing is completed (step S 709 ). When the registration processing is not completed yet, the procedures in and after S 708  are repeated, while when the registration processing is completed, the procedure advances to the step S 710 . In the step S 710 , the positioning mark formed in the image formation apparatus  12  on the upstream side is read, and it is determined whether or not the read positioning mark is on a sheet on which the image is to be formed (a sheet of concern) (step S 711 ). When the read positioning mark is on the sheet on which the image is to be formed (the sheet of concern), the procedure advances to a step S 712  to perform the image formation and, otherwise, the procedure in the step S 710  is repeated. 
     When the image formation apparatus of concern (the image formation apparatus  14 ) is disposed on the upstream side, the procedure advances to the step S 704  from the step S 703 , and it is determined whether or not the operation mode of the tandem printing system  10  is the color mode. When the operation mode is the color mode, the registration processing is performed (step S 705 ), and it is determined whether or not the registration processing is completed (step S 706 ). When the registration processing is completed, the procedure advances to the step S 712  and, otherwise, the procedure in the step S 705  is continued. 
     After the image formation processing in the step S 712  is started, it is determined whether or not subsequent processing for the continuous paper P is completed (step S 713 ) and, when the subsequent processing for the continuous paper P is completed, the procedure advances to a step S 714  to stop the transport, and the processing is ended (step S 715 ). 
     (Feature of Operation Example 1) 
     As described above, in the present exemplary embodiment, after the continuous paper P reaches the image formation apparatus  14  disposed on the downstream side in the tandem printing system  10 , the image formation apparatus  12  on the upstream side performs the blank paper sending (blank sending) of the continuous paper P in which the image formation on one side is not performed during the time period of the registration processing performed in the image formation apparatus  14  so that the portion of the continuous paper P formed with the image on one side does not reach the image formation apparatus  14  during the above-mentioned registration processing. 
     That is, in the processing shown in  FIGS. 6 and 7 , the blank paper sending (step S 605 ) is performed in the image formation apparatus  12  in order to secure the time required for the registration processing in the image formation apparatus  14 . Subsequently, timing for terminating the blank paper sending is calculated in the apparatus performing the blank paper sending (in the image formation apparatus  12 ), the blank paper sending is terminated on the basis of the result of the calculation (step S 606 ), and the image formation is started (step S 609 ). 
     According to this implementation, the principle in  FIGS. 5A to 5C  are realized. That is, even when the registration processing is performed in the image formation apparatus  14  on the downstream side, and the image formation is not performed during the registration processing in the image formation apparatus  14 , the blank paper sending is performed in the image formation apparatus  12 , and timing for the image formation with respect to the front and back sides of the continuous paper P is thereby adjusted so that it becomes possible to perform the image formation on the downstream side at the timing that allows the positions of the images on the front and back sides to be matched. Consequently, in the case where the types of the image formation apparatuses are different, and the registration processing is performed on the downstream side instead of performing the registration processing on the upstream side, it is possible to match the positions of the images on the front and back sides of the continuous paper P. 
     Operation Example 2 
     Operation Example 2 different from Operation Example 1 will be described.  FIG. 8  shows procedures of processing of Operation Example 2 that is performed in the image formation apparatus  12 . In  FIG. 8 , parts provided with the same reference numerals of  FIG. 6  are the same as those in  FIG. 6 . Hereinbelow, a description will be given of a part of the processing that is different from that in  FIG. 6 . 
     In the processing in  FIG. 8 , after the blank paper sending in the step S 605  is performed, it is determined whether or not a trigger is received (step S 606 ′). The trigger is a signal that reports the completion of the registration processing in the image formation apparatus  14 . When the registration processing in the image formation apparatus  14  is completed, a signal reporting the completion is sent as the trigger to the image formation apparatus  12  from the image formation apparatus  14 . Upon reception of the signal as the trigger, the image formation apparatus  12  advances the procedure to the step S 609  from the step S 606 ′ to start the image formation processing. Other procedures in  FIG. 8  are the same as those in  FIG. 6 . 
       FIG. 9  shows procedures of an operation of the image formation apparatus  14  to be paired with the image formation apparatus  12  where the processing in  FIG. 8  is performed. In  FIG. 9 , parts provided with the same reference numerals of  FIG. 7  are the same as those in  FIG. 7 . Hereinbelow, a description will be given of a part of the processing that is different from that in  FIG. 7 . In this case, at the point of time when the registration processing in the step S 709  is completed, the processing of transmitting the trigger toward the image formation apparatus  12  from the image processing apparatus  14  is performed (step S 709 ′). When the trigger is received in the image formation apparatus  12  (the step S 606 ′ in  FIG. 8 ), the state where the blank paper sending in the step S 605  is performed is shifted to the state where the image formation processing is performed (step S 609 ). 
     (Feature of Operation Example 2) 
     In this implementation, the signal reporting the completion of the registration processing is sent to the image formation apparatus  12  from the image formation apparatus  14  on the downstream side and, upon reception of the signal, the image formation apparatus  12  stops the blank paper sending, and starts the image formation processing. Consequently, the occurrence of the inconvenience shown in  FIGS. 4A to 4C  are reliably prevented. 
     Operation Example 3 
     A description will be given of Operation Example 3 that is different from Operation Examples 1 and 2.  FIG. 10  shows procedures of processing of Operation Example 3 performed in the image formation apparatus  14 . In  FIG. 10 , parts provided with the same reference numerals of  FIG. 7  are the same as those in  FIG. 7 . Hereinafter, a description will be given of a part of the processing that is different from that in  FIG. 7 . Note that the operation of the image formation apparatus  12  in Operation Example 3 is the same as that in  FIG. 8 . 
     In this case, after the registration processing in the step S 708  is started, a procedure in a step S 708 ′ is performed. In the step S 708 ′, it is determined whether or not the sum (L 1 +L 2 ) of the transport distance of the continuous paper P after the start of the registration L 1 , and the distance between the image formation apparatuses  12  and  14  L 2  is not less than the transport distance of the continuous paper P required for the registration processing L 3 . 
     The principle of the determination content is shown in  FIGS. 11A and 11B .  FIGS. 11A and 11B  show the transport distance L 1  and the apparatus interval L 2 . Herein, the apparatus interval L 2  is a distance between the transfer position to the continuous paper P in the image formation apparatus  12  and the transfer position to the continuous paper P on the most downstream side in the image formation apparatus  14 . 
     In the case where the condition of L 1 +L 2 &lt;L 3  is satisfied (i.e., the condition of NO in the step S 708 ′), when the image formation with respect to the first side of the continuous paper P in the image formation apparatus  12  is started, at the timing prior to the completion of the registration, the image formation portion on the first side reaches the transfer position in the image formation apparatus  14 . Accordingly, timing for the image formation with respect to the second side in the image formation apparatus  14  is not secured so that it is not possible to perform the image formation in which the positions of the images on the front and back sides are matched with each other. 
     Consequently, the procedure in the step S 708 ′ in  FIG. 10  is performed and, at the stage where L 1 +L 2 ≧L 3  is satisfied, the trigger is transmitted from the image formation apparatus  14  to the image formation apparatus  12  (step S 708 ′). At the stage where the trigger is received, the step S 606 ′ in  FIG. 8  becomes YES, and the procedure is shifted from the blank paper sending in S 605  to the image formation processing in S 609  in the image formation apparatus  12 . 
     (Feature of Operation Example 3) 
     According to Operation Example 3, when L 1 +L 2 ≧L 3  in  FIGS. 11A and 11B  (L 3 : the transport distance of the continuous paper P required for the registration processing) is satisfied, the portion of the paper formed with the image on the first side does not reach the transfer position in the image formation apparatus  14  during the registration processing in the image formation apparatus  14  so that the occurrence of the inconvenience in which the positions of the images on the front and back side are not matched with each other is prevented. 
     In addition, when compared with the case of Operation Example 2, it is possible to reduce the amount of wasted continuous paper P. Specifically, in Operation Example 2, the image formation is started on the upstream side after the registration is completed on the downstream side, while in Operation Example 3, at the point of time prior to the completion of the registration on the downstream side, the timing for the image formation on the upstream side is calculated by arithmetic calculation using the data on the transport distance of the continuous paper P, and the image formation on the upstream side is started on the basis of the result of the calculation. Consequently, in Operation Example 3, it is possible to shorten the length of the continuous paper P to be subjected to the blank paper sending when compared with Operation Example 2. In other words, it is possible to reduce the amount of wasted continuous paper P when compared with Operation Example 2. 
     As another implementation of Operation Example 1, an implementation is possible in which the procedure in the step S 708 ′ is performed instead of the step S 606  in  FIG. 6 . In this case, the processing of the procedure in the step S 708 ′ is performed in the image formation apparatus  12  and, on the basis of the result of the processing, the procedure is shifted from the processing of the blank paper sending to the image formation processing in the image formation apparatus  12 . 
     (Others) 
     There may be adopted a configuration in which the program for performing the processing shown in  FIGS. 6 to 9  is stored in an appropriate storage medium, and provided therefrom. Further, there may also be adopted a configuration in which the processing shown in  FIGS. 6 to 9  is performed in the host terminal  50 , a control signal including the result of the processing in  FIGS. 6 to 9  is sent to the image formation apparatuses  12  and  14  from the host terminal  50 , and the image formation apparatuses  12  and  14  operate on the basis of the control signal. 
     The foregoing description has described the case where, because the registration needs to be performed in the image formation apparatus on the downstream side, the additional time period from the reception of the continuous paper to the start of the operation is required in the apparatus on the downstream side. However, the reason why the additional time period from the reception of the continuous paper to the start of the operation is required in the apparatus on the downstream side is not limited to the registration processing, and the reason may include other factors such as, e.g., warming-up of the fixing apparatus, cleaning of the photosensitive drums, and the like. 
     INDUSTRIAL APPLICABILITY 
     The present invention may be utilized for a technology for performing image formation with respect to a continuous recording medium using image formation apparatuses of different types. 
     The foregoing description of the exemplary embodiment of the present invention has been provided for the purpose of illustration and description. It is not intended to be exhaustive or to limit the invention to the precise forms disclosed. Obviously, many modifications and various will be apparent to practitioners skilled in the art. The embodiments were chosen and described in order to best explain the principles of the invention and its practical application, thereby enabling other skilled in the art to understand the invention for various embodiments and with the various modifications as are suited to the particular use contemplated. It is intended that the scope of the invention be defined by the following claims and their equivalents.