JP2019014218A - Image formation system and program - Google Patents

Abstract

To reduce deviation in discharge chance of droplet between corresponding discharge positions of a plurality of formation means, compared to the case where printing data in one page corresponding to each position of discharge ports is not distributed to the plurality of formation means.SOLUTION: An image formation system includes: first formation means which discharges droplet from a first discharge port to a continuous belt-like recording material to form an image; second formation means which discharges droplet from a second discharge port to the recording material to form an image; and allocation means which allocates printing data in one page corresponding to each discharge position to the first formation means or the second formation means based on a first use history of the first discharge port and a second use history of the second discharge port.SELECTED DRAWING: Figure 9

Description

  The present invention relates to an image forming system and a program.

  Some continuous-book printers that print images on roll paper that is continuous in a strip form use ink to form images. For example, Patent Document 1 focuses on the fact that the time required for data processing varies from page to page, and data for printing on the upstream side of two continuous printing presses arranged in series in the roll paper transport direction. When processing is not in time, a mechanism has been proposed in which printing of a page in which data processing is not in time is assigned to the downstream side.

Japanese Patent Laid-Open No. 2006-16583

  However, in the method of using the upstream machine exclusively of the two continuous printing presses and using the downstream machine as an auxiliary, the non-ejection period of the downstream machine may extend for a long time. In this case, if the non-ejection period of the downstream machine becomes long, nozzle clogging cannot be avoided, and many consumables are consumed for maintenance.

  Even in the method of switching the continuous printing press used for printing in units of print jobs composed of one page or a plurality of pages, the position of the nozzle actually used for ink ejection is likely to be biased depending on the content of the page, The effect of reducing the consumption of ink ejected for the purpose of preventing clogging is insufficient.

  According to the present invention, compared to the case where print data in one page corresponding to each position of the ejection port is not allocated to a plurality of forming units, the chance of ejecting droplets between the corresponding ejection positions of the plurality of forming units is increased. The object is to reduce the bias.

According to the first aspect of the present invention, there is provided a first forming means for forming an image by discharging droplets from a first discharge port to a recording material continuous in a strip shape, and a second discharge port in the recording material. A second forming unit that forms an image by ejecting liquid droplets from the first and second print means, and print data in one page corresponding to each discharge position, the first use history of the first discharge port and the second discharge An image forming system comprising: an assigning unit assigned to the first forming unit or the second forming unit based on a second use history of the exit.
A second aspect of the present invention is the image forming system according to the first aspect, wherein the allocating unit determines an allocation destination of the print data for each continuous partial area in one page.
A third aspect of the present invention is the image forming system according to the second aspect, wherein the allocating unit determines the allocation destination of the print data by using a vector image as a processing unit.
A fourth aspect of the present invention is the image forming system according to the second aspect, wherein the allocating unit determines an allocation destination of the print data in units of line segments.
According to a fifth aspect of the present invention, in the image forming apparatus according to the second aspect, the allocation unit determines the allocation destination of the print data in units of a plurality of areas that divide one page in the conveyance direction of the recording material. System.
According to a sixth aspect of the present invention, the allocating unit allocates a part of the print data of the partial area corresponding to one ejection position to the first forming unit and the rest to the second forming unit. The image forming system according to claim 2, wherein the image forming system is assigned.
According to a seventh aspect of the present invention, in the first aspect, the assigning unit determines an assignment destination of the print data based on each use frequency in the first use history and the second use history. This is an image forming system.
According to an eighth aspect of the present invention, when the usage frequency of the first usage history is lower than the usage frequency of the second usage history, the assigning unit stores the print data in the first forming unit. The image forming system according to claim 7, wherein the print data is allocated to the second forming unit when the frequency of use and the use frequency of the second use history is lower than the use frequency of the first use history. is there.
In the invention according to claim 9, the allocating unit determines whether or not the corresponding use frequency is lower than a predetermined threshold for each of the first forming unit and the second forming unit. When the determination result that the value is lower than the threshold value is obtained, the formation unit positioned on the upstream side with respect to the conveyance direction of the recording material is preferentially determined as the print data allocation destination. Item 8. The image forming system according to Item 7.
According to a tenth aspect of the present invention, in the first aspect, the allocating unit determines an allocation destination of the print data based on each non-use period in the first usage history and the second usage history. It is an image forming system of description.
According to an eleventh aspect of the present invention, the allocating unit determines, for each of the first forming unit and the second forming unit, whether the corresponding non-use period exceeds a predetermined threshold value. When the determination result that the threshold value is exceeded is obtained, the print data allocation destination is determined with priority given to the forming unit positioned upstream in the conveyance direction of the recording material. 10. The image forming system according to 10.
According to a twelfth aspect of the present invention, in the image forming system according to the eleventh aspect, the threshold value is designated by a user within an allowable range of the non-use period.
According to a thirteenth aspect of the present invention, there is provided a first discharge port for a first forming unit that forms an image by discharging droplets from a first discharge port to a recording material that is continuous in a strip shape. The second use history of the second discharge port, and the second forming means for forming an image by discharging droplets from the second discharge port to the recording material. And the print data in one page corresponding to each ejection position are transferred to the first forming means or the second forming means based on the first use history and the second use history. This is a program for executing the function to be assigned.

According to the first aspect of the present invention, compared to the case where print data in one page corresponding to each position of the discharge port is not allocated to the plurality of forming units, the discharge positions corresponding to the plurality of forming units are not changed. Uneven distribution of droplets can be reduced.
According to the second aspect of the present invention, the ejection opportunity is easily distributed to the plurality of forming units.
According to the third aspect of the present invention, the ejection opportunity is easily distributed to the plurality of forming units.
According to the fourth aspect of the present invention, the ejection opportunity is easily distributed to the plurality of forming units.
According to the fifth aspect of the present invention, the ejection opportunity is easily distributed to the plurality of forming units.
According to the sixth aspect of the present invention, the ejection opportunity is easily distributed to the plurality of forming units.
According to the seventh aspect of the present invention, the assignment destination can be determined so that the difference in ejection opportunity among the plurality of forming units is reduced.
According to the eighth aspect of the present invention, the assignment destination can be determined so that the difference in ejection opportunity among the plurality of forming units is reduced.
According to the ninth aspect of the present invention, it is possible to determine the assignment destination so that the difference in ejection opportunity among the plurality of forming units is reduced.
According to the tenth aspect of the present invention, it is possible to determine the assignment destination while taking into account the length of the non-use period.
According to the eleventh aspect of the present invention, it is possible to determine the assignment destination while taking into account the length of the non-use period.
According to the twelfth aspect of the present invention, it is possible to determine the assignment destination while taking into account the length of the non-use period.
According to the thirteenth aspect of the present invention, compared to the case where print data in one page corresponding to each position of the discharge port is not allocated to the plurality of forming units, the discharge positions corresponding to the plurality of forming units are not changed. Uneven distribution of droplets can be reduced.

1 is a diagram illustrating an example of a front external configuration of a printing system according to Embodiment 1. FIG. FIG. 2 is a diagram for explaining a hardware configuration example of a first printing apparatus and a second printing apparatus that constitute the printing system according to the first embodiment. 3 is a diagram illustrating an example of a functional configuration of a control device according to Embodiment 1. FIG. FIG. 6 is a diagram illustrating a print job received by a print job receiving unit. It is a figure which shows an example of the alignment mark used for detection of conveyance deviation. It is a figure explaining the analysis operation by a print data analysis part. It is a figure which shows the example of the management information managed based on a usage history. (A) is for use history management in the upstream machine, and (B) is for use history management in the downstream machine. It is a figure explaining the example of the total discharge amount according to the nozzle position managed per page. 3 is a flowchart for explaining an overview of processing operations in the first embodiment. 7 is a part of a flowchart for explaining in detail an assignment destination determination process according to the first embodiment. FIG. 10 is the remaining part of the flowchart for explaining in detail the assignment destination determination processing in the first embodiment. FIG. It is a figure explaining the relationship between a non-printable near threshold and a non-printable threshold. 10 is a flowchart for explaining an outline of processing operation in the second embodiment. It is a figure explaining the relationship between 1 page and a partial page. 10 is a flowchart for explaining an outline of processing operations in the third embodiment. It is a figure explaining the example of the image contained in 1 page. (A) shows an example of printing one page, and (B) shows the distribution of ejection amount for each nozzle position. It is a figure explaining the example of allocation to an upstream machine among the images contained in 1 page. (A) shows an example of printing one page, and (B) shows the distribution of ejection amount for each nozzle position. It is a figure explaining the example of allocation to a downstream machine among the images contained in 1 page. (A) shows an example of printing one page, and (B) shows the distribution of ejection amount for each nozzle position. 10 is a flowchart illustrating an overview of processing operations in a fourth embodiment. It is a flowchart explaining the detailed content of a nozzle clogging suppression process.

  Hereinafter, embodiments will be described in detail with reference to the accompanying drawings.

<Embodiment 1>
<System configuration>
In this embodiment, a printing system that prints an image by ejecting ink droplets onto a roll paper or a continuous form (hereinafter collectively referred to as “continuous paper”) that is continuous in a band shape will be described. Note that examples of continuous paper are not limited to roll paper and continuous forms. For example, continuous slips and form sheets are also included.
FIG. 1 is a diagram illustrating an example of a front external configuration of a printing system 1 according to the first embodiment.
Here, the printing system 1 is an example of an image forming system, and the continuous paper P is an example of a recording material that is continuous in a strip shape.

The printing system 1 according to the present embodiment includes two printing units (that is, the first printing device 11 and the second printing device 12) that form ink jet images on the continuous paper P and roll the continuous paper P. Of the continuous paper P between the above-mentioned apparatuses, the pre-processing device 13 loaded with the supply roll 13A wound in a shape, the post-processing device 14 loaded with the winding roll 14A for winding the continuous paper P in a roll shape, and the like. And buffer devices 15, 16 and 17 for adjusting the length to an integral multiple of the page length.
The ink droplet here is an example of a droplet.
The first printing apparatus 11 is an example of a first forming unit, and the second printing apparatus 12 is an example of a second forming unit.

In the case of the present embodiment, the first printing device 11 and the second printing device 12 are connected in series with respect to the transport direction of the continuous paper P. In FIG. 1, the conveyance direction of the continuous paper P is indicated by an arrow.
Accordingly, the first printing apparatus 11 in the present embodiment is located on the upstream side of the conveyance path, and the second printing apparatus 12 is located on the downstream side of the conveyance path. Therefore, in the following description, the first printing apparatus 11 may be referred to as an upstream machine, and the second printing apparatus 12 may be referred to as a downstream machine.
The sheet-like continuous paper P that is continuous in a belt shape in the transport direction is continuously transported from the pre-processing device 13 to the post-processing device 14.

The first printing apparatus 11 includes a control apparatus 11A that executes various processes and controls necessary for execution of printing, and an image output apparatus 11B that forms an image by ejecting ink droplets onto the conveyed continuous paper P. Have.
The control device 11A includes a data processing unit 11A1 that generates print data based on a print job, and a mechanism control unit 11A2 that controls the operation of a mechanism unit that constitutes the image output device 11B.

The data processing unit 11A1 executes, for example, image distortion correction, image rotation, color conversion, gradation conversion, color correction, raster conversion, and the like as processing for generating print data. Since the contents of these processes are known processes, a detailed description thereof will be omitted. The print data gives the presence / absence and discharge amount of ink droplets at each nozzle.
Here, the nozzle provided in the first printing device 11 is an example of a first ejection port, and the nozzle provided in the second printing device 12 is an example of a second ejection port.
In addition, the data processing unit 11A1 also executes a process of assigning the print data to the upstream machine or the downstream machine for each position of the nozzle that ejects the ink droplets as a process of generating the print data. Details of this processing will be described later.
The mechanism control unit 11A2 controls the operation of the mechanism unit that conveys the continuous paper P and the ink droplet ejection operation by the head unit.

On the other hand, the second printing apparatus 12 includes a control apparatus 12A that executes various processes and controls necessary for execution of printing, and an image output apparatus 12B that forms an image by ejecting ink droplets onto the continuous paper P being conveyed. And have.
The configurations of the control device 12A and the image output device 12B are the same as the configurations of the control device 11A and the image output device 11B. Therefore, the control device 12A includes a data processing unit 12A1 and a mechanism control unit 12A2.
In the example of FIG. 1, the control device 11A is built in the first printing device 11 and the control device 12A is built in the second printing device 12, but these are the first printing device 11 and the second printing device. It may be accommodated in a control device provided in a separate housing from the device 12.

As the head unit in the present embodiment, a line head having a printing width equal to or larger than the width of a region where an image is formed is used.
The line head has a configuration in which a plurality of nozzle chips in which nozzle (small hole) groups for ejecting ink droplets are formed are arranged in the printing width direction. Incidentally, the direction of the printing width is a direction intersecting with the conveyance direction of the continuous paper P, and is a so-called main scanning direction.

The head units in the present embodiment correspond to four types of yellow (Y), magenta (M), cyan (C), and black (K), and are arranged in order along the transport direction. Note that the arrangement order from the upstream side to the downstream side is not limited to yellow (Y), magenta (M), cyan (C), and black (K).
Further, a head unit capable of ejecting ink droplets corresponding to colors other than these four colors or a head unit capable of ejecting ink droplets of the same color but having different densities may be used.

  In addition, a head unit that ejects ink droplets used for forming a layer serving as a base of an image to be formed or a layer covering the surface of a printed image may be used. For example, a head unit that discharges other ink colors such as gold, silver, and white may be used. Further, for example, a head unit that discharges ultraviolet curable ink droplets may be used.

  When images are formed on both sides of the continuous paper P, a buffer device 16 having a reversing mechanism for reversing the front and back surfaces between the time when the continuous paper P is carried in and the time when the continuous paper P is carried out is used. However, in the present embodiment, since it is assumed that an image is formed on one side, the buffer device 16 that does not have a reversing mechanism or the buffer device 16 in which the operation of the reversing mechanism is invalidated is used.

<Configuration of each device>
FIG. 2 is a diagram illustrating a hardware configuration example of the first printing apparatus 11 and the second printing apparatus 12 that configure the printing system 1 according to the first embodiment.
As described above, since the first printing device 11 and the second printing device 12 have the same hardware configuration, only the first printing device 11 will be described below.
As described above, the first printing device 11 includes the control device 11A and the image output device 11B.

  11A of control apparatuses are comprised as what is called a computer, MPU (Micro Processing Unit) 21 which controls the whole apparatus, ROM (Read Only Memory) 22 which memorize | stores programs, such as firmware, and RAM (RAM used as an execution area of a program) Random Access Memory) 23, a communication interface (IF) 24 used for communication with the image output device 11B, a communication interface (IF) 25 used for communication with the control device 12A on the downstream side, and a user interface An operation panel 26 that is used to display a screen and receive an operation input, a panel interface (IF) 27 that exchanges data between the operation panel 26, and a hard disk device that stores image data and the like corresponding to a print job ( HDD) 28.

  The image output device 11B receives data between the communication unit 31 that communicates with the communication interface (IF) 24 in the control device 11A, the head unit 32 that corresponds to various ink droplets as described above, and the head unit 32. It has a head interface (IF) 33 for transferring, a transfer mechanism 34 for transferring the continuous paper P, and a transfer interface (IF) 35 for transferring data between the transfer mechanism 34.

In the case of the present embodiment, a conveyance deviation detection sensor 36 is provided as a configuration unique to the image output device 12B that constitutes the second printing device 12 used as a downstream machine.
The conveyance deviation detection sensor 36 is provided for the purpose of detecting a deviation amount in the printing width direction of the continuous paper P that is generated while being conveyed. For this reason, the conveyance deviation detection sensor 36 is disposed upstream of the head unit 32 where printing is started. The deviation amount detected by the conveyance deviation detection sensor 36 is used for adjusting the deviation amount of the continuous paper P in the print width direction. For this reason, the second printing apparatus 12 is provided with a position adjusting mechanism (not shown).
All of the members described above including the conveyance deviation detection sensor 36 are known. Therefore, a detailed description of these members is omitted.

FIG. 3 is a diagram illustrating a functional configuration example of the control device 11A according to the first embodiment. The functional configuration shown in FIG. 3 is realized through execution of firmware.
From the viewpoint of the functional configuration, the control device 11A includes a print job reception unit 41 that receives a print job from an external device, a print data analysis unit 42 that analyzes print data for each nozzle position, and an upstream machine or print data for each nozzle position. An allocation destination determination unit 43 to be assigned to the downstream machine and a usage history management unit 44 for managing the usage history of each nozzle for each of the upstream machine and the downstream machine are provided.
The control device 11A viewed from the viewpoint of the functional configuration is an example of an assignment unit.

In the case of this embodiment, the print job is composed of a plurality of pages.
FIG. 4 is a diagram for explaining a print job accepted by the print job accepting unit 41. The example of FIG. 4 represents a case where the print job is composed of 100 pages # 1 to # 100.
Note that, on the continuous paper P shown in FIG. 4, an alignment mark 51 is printed at the top of each page in the transport direction. The alignment mark 51 is printed by the upstream machine (that is, the first printing apparatus 11).
Here, the head portion refers to the end portion side of each page where printing is started.

FIG. 5 is a diagram illustrating an example of the alignment mark 51 used for detection of conveyance deviation. The alignment mark 51 has a shape in which a linear blank is provided in one diagonal direction of a square, that is, a shape obtained by dividing the square into two triangular patterns 51A and 51B having the same area.
The conveyance deviation detection sensor 36 (see FIG. 2) described above has a light source that irradiates the continuous paper P with spot light and a light receiving unit that receives reflected light from the continuous paper P of the irradiated spot light. . The light receiving unit detects a distance L1 that passes over the pattern 51A and a distance L2 that passes over the pattern 51B when the spot light crosses the alignment mark 51 in the transport direction.

A case where the distance L1 is equal to the distance L2 (a case where the spot light crosses the position _PREF ) represents a conveyance state in which there is no conveyance deviation. On the other hand, if the distances L1 and 2 are different (for example, when the position P _R crosses spotlight) represents a case where a conveyance deviation. The direction of the conveyance deviation can be determined depending on which of the distance L1 and the distance L2 is large, and the magnitude of the conveyance deviation can be determined by the difference or ratio between the distance L1 and the distance L2. Position P _R in the figure indicates that the continuous paper P is deviated leftward in the drawing the direction of the printing width.
The MPU 21 of the second printing apparatus 12 that is a downstream machine controls the transport mechanism 34 and an adjustment mechanism (not shown) based on the detected amount of deviation, and the area printed by the own machine is compared with the area printed by the upstream machine. Adjust so that it does not shift.

Returning to the description of FIG.
The print data analysis unit 42 analyzes the number of appearances (discharge amount) of print data for each nozzle position for each page constituting the print job. Since the analysis target is a print job, the analysis result is a predicted value.
FIG. 6 is a diagram for explaining an analysis operation by the print data analysis unit 42. In the example shown in FIG. 6, the print pattern constituting the first page # 1 is represented by a solid color. Each square in the figure represents a unit area drawn by one ink drop. In this embodiment, this area is called a dot. FIG. 6 is designed for explanation.

In the example of FIG. 6, the head unit 32 is represented as including 13 nozzles in the main scanning direction. Of course, this number is a provisional value for explanation.
The print data analysis unit 42 (see FIG. 3) counts the number of dots constituting the print pattern included in the corresponding dot row for each nozzle position. The number of dots corresponds to the discharge amount. As shown in FIG. 6, a dot row corresponds to a dot position appearing in the carrying direction (sub-scanning direction), and the number of dots constituting the dot row corresponds to the length of one page (length in the carrying direction). To do.

  In FIG. 6, the number of constituent dots of the print pattern appearing in the dot row corresponding to each nozzle number is represented as the total ejection amount. In the example of FIG. 6, the nozzle with nozzle number 1 ejects one ink droplet during the printing period of page # 1. Hereinafter, three nozzles with nozzle numbers 2 and 3, two nozzles with nozzle numbers 4 to 6, one nozzle with nozzle number 7, two nozzles with nozzle numbers 8 to 10, nozzle numbers 11 and 12 Three nozzles and one nozzle with nozzle number 13 are discharged.

Returning to the description of FIG.
The assignment destination determination unit 43 is based on the analysis result by the print data analysis unit 42 and the use history information of each nozzle constituting each head unit 32 of the upstream machine and the downstream machine acquired from the use history management unit 44. An assignment destination of print data (dot row) corresponding to each nozzle position is determined to be an upstream machine or a downstream machine.
In the present embodiment, the usage history is information that is referred to when determining the assignment destination of the print data, and includes various index values that indicate the state of ink droplet ejection. A specific example of the usage history will be described later.
In the case of this embodiment, the assignment destination of the print data (dot row) corresponding to each nozzle position is determined with one page as a processing unit. A specific example of the determination method will be described later.

Thus, in the present embodiment, the print data allocation destination corresponding to each nozzle position is determined with one page as a processing unit. For this reason, even in the case of a print job (also referred to as variable printing) with different contents for each page, the print data of each page is changed according to the appearance status of print data corresponding to each nozzle position (for example, nozzle number 7). Whether to print on the upstream machine side or on the downstream machine side can be determined.
That is, even if the appearance position of the print data for each page is less regular, the ink droplet ejection opportunity at each nozzle position can be distributed to the upstream machine and the downstream machine. As a result, it is possible to reduce the uneven discharge opportunity at the corresponding nozzle positions between the upstream machine and the downstream machine. In other words, it is possible to avoid a situation in which the chances of ejecting ink droplets are reduced to such an extent that nozzle clogging occurs.
Information regarding the assignment destination is fed back to the use history management unit 44.

The use history management unit 44 manages the use history for each nozzle of each head unit 32 provided in each of the upstream machine and the downstream machine. Here, the usage history of each nozzle of the head unit 32 provided in the first printing apparatus 11 that is the upstream machine is an example of the first usage history, and the head unit 32 provided in the second printing apparatus 12 that is the downstream machine. The usage history of each nozzle is an example of the second usage history.
In the case of the present embodiment, the use history is given as a record of, for example, the position and time (processing timing) of the nozzle at which an ink droplet was ejected or ejected.

In addition, when there is a delay until ink droplet ejection based on the information regarding the assignment destination received feedback from the assignment destination determination unit 43 (for example, when there is a time difference until the print data is supplied to the head unit 32 by the page buffer). The usage history management unit 44 manages the usage history as a predicted value.
Incidentally, when the delay can be ignored, the information on the assignment destination that receives the feedback from the assignment destination determination unit 43 can be handled in the same way as the actual measurement value.
When the ink droplet ejection history for each head unit 32 is fed back from the image output devices 11B and 12B, the usage history management unit 44 manages the usage history of the ink droplets actually ejected from each nozzle.

FIG. 7 is a diagram illustrating an example of management information managed based on the usage history. (A) is for use history management in the upstream machine, and (B) is for use history management in the downstream machine.
The management information is information representing the usage frequency and usage status of each nozzle. For example, the final ejection time 61, the total ejection amount 62, the average ejection interval 63 per unit time, and the average ejection interval 64 per current print job. It is.

Here, the average discharge interval 63 per unit time is different from the current average discharge interval 64 per print job and gives a longer average interval considering a plurality of print jobs.
These values are calculated for each nozzle number (nozzle position). The average discharge interval 63 per unit time and the average discharge interval 64 per current print job are both examples of usage frequencies.

  FIG. 8 is a diagram illustrating an example of the total discharge amount 62 for each nozzle position managed in units of pages. FIG. 8 shows an example in which the current print job is given in 100 pages, and the total discharge amount for each nozzle position is associated with the nozzle position. For example, the total discharge amount of the nozzles corresponding to the nozzle numbers 1 to 3 corresponding to the fifth page is all 0, the total discharge amount of the nozzles corresponding to the nozzle number 4 is 8, and corresponds to the nozzle numbers 5 to 10 The total discharge amount of the nozzles to be performed is 3, and the total discharge amount of the nozzles corresponding to the nozzle numbers 11 to 13 is 0.

<Processing Operation in Embodiment 1>
FIG. 9 is a flowchart for explaining the outline of the processing operation in the first embodiment.
In the case of the present embodiment, the control device 11A of the first printing apparatus 11 as an upstream machine controls a series of processing operations through execution of the program.
Note that the processing operation shown in FIG. 9 is executed by the number of head units 32 provided in the upstream machine and the downstream machine. For example, it is executed for each of the head units 32 corresponding to yellow (Y), magenta (M), cyan (C), and black (K).
As described above, in this embodiment, the print data at each nozzle position is assigned to the upstream machine or the downstream machine in units of one page.

First, the control device 11A receives a print job (step S101). In the present embodiment, the length of one page in the conveyance direction of the continuous paper P is 60 inches, and the print job is composed of 100 pages.
The control device 11A that has received the print job updates the management information based on the use history (step S102). Specifically, the management information calculated using the allocation result for each of the upstream machine and the downstream machine is acquired.

Next, the control device 11A executes a process of assigning print data to the upstream machine or the downstream machine for each nozzle position (step S103). Specifically, the control device 11A determines, for each nozzle position, an assignment destination of print data constituting the page being processed using the management information. A detailed example of the allocation destination determination method will be described later.
Thereafter, the control device 11A calculates a total discharge amount 62 for each nozzle position, an average discharge interval 63 per unit time, and an average discharge interval 64 of the current print job for each output scheduled device (steps S104 to S106). The calculation order of each value is not limited to the example in FIG. Moreover, you may perform calculation of each value in parallel.
The calculation result here is used for updating the management information in step S102, for example.

Subsequently, the control device 11A determines whether the page being processed is the last page constituting the print job (step S107).
When a negative result is obtained (when the page being processed is not the last page of the print job), the control device 11A advances the processing target to the next page (step S108).
On the other hand, when a positive result is obtained (when the page being processed is the last page of the print job), the control device 11A ends the assignment destination determination process.

Next, a detailed example of the assignment destination executed in step S103 will be described.
FIG. 10-1 is a part of a flowchart for explaining in detail the assignment destination determination processing in the first embodiment, and FIG. 10-2 is a flowchart for explaining in detail the assignment destination determination processing in the first embodiment. Of the rest.
First, the control device 11A acquires management information of nozzle positions to be processed (step S111). The nozzle position to be processed starts from nozzle number 1. In the following description, a nozzle to be processed is referred to as a corresponding nozzle.

Next, the control device 11A determines whether there is print data at the nozzle position to be processed (step S112).
When a negative result is obtained (when there is no print data at the corresponding nozzle position), the control device 11A determines whether there is a next nozzle position (step S128).

On the other hand, when a positive result is obtained (when print data is present at the corresponding nozzle position), the control device 11A determines whether or not the continuous non-ejection time is within the no-printable threshold for the corresponding nozzle of the upstream machine. (Step S113).
The continuous non-ejection time here refers to the time during which the non-ejection state continues, and is calculated as the difference between the current time and the final ejection time. The continuous non-ejection period is an example of a non-use period.
The non-printable threshold value is an upper limit value of the continuous non-ejection time in which nozzle clogging due to ink drying does not occur. The non-printable threshold is an example of a threshold corresponding to the allowable range of the non-use period.

Note that the non-printable threshold is not a fixed value, but varies depending on the printing environment and the number of pages in the page buffer.
The printing environment here includes, for example, the type of ink, the type of head unit 32 (for example, nozzle diameter), temperature, humidity, and printing density.
The non-printable threshold value in the present embodiment is calculated by the following equation.
Non-printable threshold = printing environment threshold + correction value Here, the printing environment threshold is the number of pages determined by the printing environment described above.
The correction value is, for example, the number of pages determined by the number of pages waiting to be printed × print length ÷ print speed. The number of pages waiting for printing corresponds to the number of pages in the page buffer described above. The print length corresponds to the length of one page in the transport direction, and the print speed corresponds to the transport speed.

When a negative result is obtained in step S113 (when the continuous non-ejection time of the upstream machine exceeds the non-printable threshold), the control device 11A displays on the user interface UI that there is a possibility of printing fading for the upstream machine. (Step S114).
Following this display, the control device 11A stops printing by the upstream machine, then ejects ink droplets from all nozzles of the upstream machine, and then restarts printing of the upstream machine (step S115). This operation is executed for the purpose of preventing nozzle clogging.
After step S115 ends, the control device 11A proceeds to step S104.

On the other hand, when a positive result is obtained in step S113 (when the continuous non-ejection time of the upstream machine does not exceed the non-printable threshold), the control device 11A determines that the continuous non-ejection time for the downstream machine is within the non-printable threshold. Is determined (step S116).
If a negative result is obtained in step S116, the control device 11A displays on the user interface UI that there is a possibility of faint printing for the downstream machine (step S117).
Following this display, the control device 11A stops printing by the downstream machine, discharges ink droplets from all nozzles of the downstream machine, and then restarts printing of the downstream machine (step S118).
After step S118 ends, the controller 11A proceeds to step S104.

If an affirmative result is obtained in step S116, the control device 11A determines whether or not the continuous non-ejection time of the upstream machine is within the non-printable near threshold (step S119).
FIG. 11 is a diagram illustrating the relationship between the non-printable near threshold and the non-printable threshold. The non-printable near threshold value is a threshold value (within an allowable range) smaller than the non-printable threshold value specified by the user, and is a preliminary threshold value used in order not to stop printing of the upstream machine and the downstream machine.
If a negative result is obtained in step S119, the control device 11A sets the upstream machine as a print data output scheduled device corresponding to the corresponding nozzle (step S120).
After step S120 ends, the control device 11A proceeds to step S104.

On the other hand, when a positive result is obtained in step S119, the control device 11A determines whether or not the continuous non-ejection time of the downstream machine is within the non-printable near threshold (step S121). This determination process is provided in order to avoid the entire stop of printing as shown in step S115 or step S118.
If a negative result is obtained in step S121, the control device 11A sets the downstream machine as a print data output scheduled device corresponding to the corresponding nozzle (step S122).
After step S122 ends, the control device 11A proceeds to step S104.

When a positive result is obtained in step S121, the control device 11A determines whether or not the appearance interval of the corresponding nozzle of the upstream machine is within the threshold (step S123).
In this embodiment, the average discharge interval per time or the average discharge interval of the current print job is used as the appearance interval. This is because it is necessary to preferentially assign print data when there are few ejection opportunities for the corresponding nozzle.
When a negative result is obtained in step S123 (when it is determined that there are few ejection opportunities for the corresponding nozzle of the upstream machine), the control device 11A sets the upstream machine as the output scheduled device (step S124).
After step S124 ends, the control device 11A proceeds to step S104.

On the other hand, when a positive result is obtained in step S123, the control device 11A determines whether the appearance interval of the corresponding nozzle of the downstream machine is within the threshold value (step S125).
When a negative result is obtained in step S125 (when it is determined that there are few ejection opportunities for the corresponding nozzle of the downstream machine), the control device 11A sets the downstream machine as the output scheduled device (step S126).
After step S126 ends, the controller 11A proceeds to step S104.

If a positive result is obtained in step S125, the control device 11A proceeds to step S127. The processing in step S127 is executed when there are many ejection opportunities for both the corresponding nozzle on the upstream machine side and the corresponding nozzle on the downstream machine side (both the same nozzle positions).
At this time, 11 A of control apparatuses set the one where an appearance interval is larger as an output plan apparatus (step S127). For example, when the appearance interval of the corresponding nozzle in the upstream machine is larger than the appearance interval of the corresponding nozzle in the downstream machine, the upstream machine having a smaller discharge opportunity is set as the output scheduled apparatus. On the other hand, when the appearance interval of the corresponding nozzle in the downstream machine is larger than the appearance interval of the corresponding nozzle in the upstream machine, the downstream machine having a smaller discharge opportunity is set as the output scheduled apparatus.

When step S127 ends, the control device 11A proceeds to step S128 described above. In step S128, the control device 11A determines whether there is a next nozzle position.
Here, when a positive result is obtained in step S128, the control device 11A moves the nozzle position to be processed to the next nozzle (step S129), and executes the processes from step S111 to step S127 described above. .
When the final nozzle position is reached and a negative result is obtained in step S128, the control device 11A proceeds to step S104.

<Effect of Embodiment 1>
If the printing system 1 in Embodiment 1 is used, the printing data in one page can be allocated to the upstream machine or the downstream machine for each nozzle position based on the usage history of each nozzle position. That is, an image in one page can be printed using an upstream machine and a downstream machine.
For example, print data for nozzle positions with an odd nozzle number can be printed with an upstream machine, and print data for nozzle positions with an even nozzle number can be printed with a downstream machine.

For this reason, for example, even when the contents of an image constituting a print job differ from page to page, ink droplets can be preferentially ejected from a nozzle with a larger printing interval or a nozzle closer to the printable threshold, and the upstream machine and the downstream machine Thus, it is possible to reduce the deviation of the ink droplet ejection opportunities between the corresponding nozzle positions.
As a result, the possibility of nozzle clogging can be reduced while reducing the consumption of ink that does not contribute to image formation.

In addition, since the ejection opportunities of each nozzle increase, the occurrence of uneven print density due to ejection failure is also reduced. This leads to an improvement in image quality.
In addition, since the ejection opportunities of each nozzle increase, the possibility that components that are movable parts are fixed is reduced, and mechanical failure is less likely to occur.
Further, when the state where the printing surface is limited to one side of the continuous paper P is continued for a long period of time, one of the two printing machines constituting the printing system 1 is often used and the other is paused. However, in such a usage pattern, even if the nozzle surface of the head unit 32 is closed with a cap, the ink is dried and nozzle clogging is likely to occur.
However, as in the first embodiment, by adopting a method of printing one page using an upstream machine and a downstream machine, it is possible to reduce the forced ejection of ink droplets for replacement of storage liquid and resumption of operation. And wasteful use of consumables can be reduced.

<Embodiment 2>
In the first embodiment described above, the control device 11A of the upstream machine assigns print data constituting each page to the upstream machine or the downstream machine for each nozzle position. However, in this embodiment, one page is continuously displayed. A method of dividing the paper P into a plurality of partial pages in the conveyance direction and determining a print data allocation destination for each partial page is adopted.

FIG. 12 is a flowchart for explaining the outline of the processing operation in the second embodiment.
In FIG. 12, reference numerals corresponding to those corresponding to FIG. 9 are given.
Also in the present embodiment, the control device 11A of the first printing device 11 as an upstream device controls a series of processing operations through execution of the program.
In the case of the present embodiment, the control device 11A executes a process of dividing one page into partial pages after receiving a print job (step S201). In other words, in the present embodiment, one page is divided into a plurality of partial pages in the conveyance direction of the continuous paper P. The partial page here is an example of a plurality of areas into which one page is divided.

By dividing one page into partial pages and assigning the print data corresponding to each partial page to the upstream or downstream machine, the print data corresponding to one nozzle position is sent to both the upstream and downstream machines within one page. It becomes possible to assign.
For example, when the length of one page is 60 inches, the length of the partial page is 3 inches. In this case, one page is divided into 20 partial pages.
The more partial pages that make up one page, the easier it is for print data corresponding to one nozzle position to be assigned to both the upstream and downstream machines, but the increase in the number of partial pages that make up one page increases the processing load. Accompany. In addition, there is a lower limit on the length of the partial page in relation to the conveyance speed of the continuous paper P. In the present embodiment, this lower limit value is also referred to as a print unit length.

FIG. 13 is a diagram for explaining the relationship between one page and a partial page.
FIG. 13 shows an example in which one page is composed of five partial pages. That is, the length of the partial page is four print unit lengths.
In the case of the present embodiment, print data corresponding to one nozzle position is assigned to an upstream machine or a downstream machine in units of partial pages, but the alignment mark 51 for alignment is at the top position of the page. If it is limited, the displacement of the print position corresponding to one nozzle position tends to increase as the distance from the alignment mark 51 increases (the lower end of one page).
Therefore, in the present embodiment, the alignment mark 51 is printed at the head position of the partial page, and even when the print data corresponding to one nozzle position is assigned to the upstream machine and the downstream machine, The deviation is made small.

However, the printing position of the alignment mark 51 is not limited to the partial page that is the determination unit of the assignment destination. For example, the alignment mark 51 may be arranged for each print unit length. If the number of the alignment marks 51 is large, the number of adjustment positions of the positional deviation at each position along the conveyance direction of one page increases, so that the positional deviation can be further reduced.
The problem of misalignment is also common in the first embodiment in which print data at each nozzle position is assigned to the upstream and downstream machines in units of one page, and in later-described third and fourth embodiments. Therefore, in these embodiments, the alignment marks 51 may be formed at a plurality of positions.

Returning to the description of FIG.
When the division into the partial pages is completed, the control device 11A sequentially executes the processes in steps S102 to S106 as in the first embodiment, and assigns print data corresponding to each nozzle position for each partial page. To decide.
Thereafter, the control device 11A determines whether or not the partial page being processed is the last partial page (step S202).
If a negative result is obtained here, the control device 11A advances the partial page to be processed to the next partial page (step S203). When proceeding to the next partial page, the control device 11A returns to step S102 and executes the series of processes described above.

On the other hand, if a positive result is obtained in step S202, the control device 11A determines whether or not it is the last page (step S204).
If a negative result is obtained here, the control device 11A advances the page to be processed to the next page (step S205). When proceeding to the next page, the control device 11A returns to step S201 and executes the series of processes described above.
On the other hand, when a positive result is obtained in step S204, the control device 11A ends the series of processes described above.

<Effect of Embodiment 2>
If the printing system 1 according to the second embodiment is used, it becomes easy to assign print data in one page corresponding to one nozzle position to both the upstream machine and the downstream machine. For example, when print data in one page corresponding to one nozzle position appears in different partial pages, ink droplet ejection opportunities are given to the upstream nozzle and the downstream nozzle corresponding to one nozzle position, respectively. Can be assigned.
As a result, even if there is a deviation in the appearance position of the print data in one page, it is possible to assign a discharge opportunity to both the upstream machine and the downstream machine.

<Embodiment 3>
In the second embodiment, one page is divided into a plurality of partial pages in the transport direction of the continuous paper P, and the print data allocation destination is determined for each partial page. A method is adopted in which the print data allocation destination is determined in units of images included therein.

FIG. 14 is a flowchart for explaining the outline of the processing operation in the third embodiment.
In FIG. 14, reference numerals corresponding to those corresponding to FIG. 9 are given.
Also in the present embodiment, the control device 11A of the first printing device 11 as an upstream device controls a series of processing operations through execution of the program.
In the case of the present embodiment, the control device 11A executes a process of dividing one page into image units after receiving a print job (step S301). In the case of the present embodiment, an image refers to a continuous area as an independent area among partial areas including print data. Each image is an example of a partial region continuous within one page and an example of a plurality of regions that divide one page.

FIG. 15 is a diagram illustrating an example of an image included in one page. (A) shows an example of printing one page, and (B) shows the distribution of ejection amount for each nozzle position.
In the example of FIG. 15, only one alignment mark 51 is arranged at the head portion in order to assign print data corresponding to each nozzle position to the upstream machine and the downstream machine in units of one page.
In the example of FIG. 15, four images are included. The line segment image 71 extends in the transport direction, the line segment image 72 extends in the direction intersecting the transport direction, the ellipse image 73, and the rectangular image 74. The line segment images 71 and 72, the ellipse image 73, and the rectangular image 74 all belong to the graphic image. The graphic image includes the alignment mark 51 described above.

Of course, the number and type of images are only examples. For example, the image includes characters, patterns, etc., and may be distinguished by layer.
In addition, each image may be a raster image (a so-called bitmap image) that is a set of dots, or may be a vector image expressed by a plurality of coordinate points and lines connecting them.
The control device 11A extracts an image included in a page to be processed through image processing and analysis processing.

In the case of the example in FIG. 15, there are opportunities to eject ink droplets at many nozzle positions except for some nozzle positions.
By dividing one page into image units and assigning the print data corresponding to each image to the upstream machine or downstream machine, the print data corresponding to one nozzle position is divided into a plurality of parts within one page, and the upstream machine or downstream machine. It becomes possible to assign to the machine.

FIG. 16 is a diagram illustrating an example of assignment to an upstream device among images included in one page. (A) shows an example of printing one page, and (B) shows the distribution of ejection amount for each nozzle position.
In the example of FIG. 16, the alignment mark 51 and the line segment image 72 extending in the direction crossing the transport direction are assigned to the upstream machine, and ink droplet ejection opportunities are assigned to many nozzle positions on the upstream machine side. It has been.

FIG. 17 is a diagram for explaining an example of assignment to downstream devices among images included in one page. (A) shows an example of printing one page, and (B) shows the distribution of ejection amount for each nozzle position.
In the example of FIG. 17, a line segment image 71 extending in the transport direction, an elliptic image 73, and a rectangular image 74 are assigned to the downstream machine, and ink droplet ejection opportunities are assigned to many nozzle positions on the downstream machine side. It has been.
Note that the image allocation shown in FIGS. 16 and 17 is not simply determined so as to reduce the deviation in the number of nozzles that eject ink droplets within a page, but as described later, the use of each nozzle is determined. Determined based on history information.

Returning to the description of FIG.
When the dividing process into a plurality of images included in the page to be processed is completed, the control device 11A sequentially executes the processes in steps S102 to S106 for one image selected as the process target, and sets the individual nozzle positions. Determine the assignment destination of the corresponding print data.
Thereafter, the control device 11A determines whether or not the image to be processed is the last image in the page (step S302).
If a negative result is obtained here, the control device 11A advances to the next image as a processing target (step S303). When the next image is selected, the control device 11A returns to step S102 and executes the series of processes described above.

On the other hand, if a positive result is obtained in step S302, the control device 11A determines whether or not the page is the last page (step S304).
If a negative result is obtained here, the control device 11A advances the page to be processed to the next page (step S305). When proceeding to the next page, the control device 11A returns to step S301 and executes the series of processes described above.
On the other hand, when a positive result is obtained in step S304, the control device 11A ends the series of processes described above.

<Effect of Embodiment 3>
If the printing system 1 according to the third embodiment is used, print data in one page corresponding to one nozzle position can be assigned to an upstream machine or a downstream machine in image units. For this reason, when the print data in one page corresponding to one nozzle position appears in different images, ink droplets are ejected to each of the upstream nozzle and the downstream nozzle corresponding to one nozzle position. Can be assigned.
As a result, even if there is a bias in the appearance position of the print data in one page, it is possible to assign a discharge opportunity to both the upstream machine and the downstream machine.

<Embodiment 4>
In the present embodiment, in addition to the processing operation shown in the third embodiment, a processing function for suppressing clogging of a specific nozzle with few ink droplet ejection opportunities is added.
FIG. 18 is a flowchart for explaining the outline of the processing operation in the fourth embodiment.
In FIG. 18, reference numerals corresponding to those corresponding to FIG. 14 are given.
Also in the present embodiment, the control device 11A of the first printing device 11 as an upstream device controls a series of processing operations through execution of the program.

The processing unique to the processing procedure shown in FIG. 18 is step S401 that is executed after the print data allocation processing for the last image in the page is completed (after a positive result is obtained in step S302).
In step S401, nozzle clogging suppression processing is executed for specific nozzles that have few ink droplet ejection opportunities in a page to be processed.

FIG. 19 is a flowchart illustrating the detailed contents of the nozzle clogging suppression process.
The process shown in FIG. 19 is executed in order for each nozzle position constituting the head unit 32.
First, the control device 11A determines whether or not the continuous non-ejection time of the upstream machine corresponding to the nozzle position to be processed is within the non-printable near threshold (step S411).
The non-printable near threshold here corresponds to the threshold described in the first embodiment (see FIG. 11).

If a negative result is obtained in step S411, the control device 11A selects a blank area where no print data exists and adds the print data to the corresponding nozzle of the upstream machine (step S412). Step S412 is executed for the purpose of forcibly ejecting ink droplets for the corresponding nozzles whose continuous non-ejection time is longer than the threshold set by the user. The reason why the blank area is selected is to make the ejection position of the forcibly ejected ink droplets inconspicuous. Since the ejected ink droplets are small, the image quality is not affected visually.
The blank area is selected in order to prevent color mixing with ink droplets ejected by the downstream machine.

On the other hand, if a positive result is obtained in step S411, the control device 11A determines whether or not the continuous non-ejection time of the downstream machine corresponding to the nozzle position to be processed is within the non-printable near threshold (step S413). ).
If a negative result is obtained in step S413, the control device 11A selects a blank area where no print data exists and adds the print data to the corresponding nozzle of the downstream machine (step S414).

After execution of step S412, when a positive result is obtained in step S413, or after execution of step S414, the control device 11A calculates a total discharge amount for each nozzle position for each output scheduled device (step S415). ).
Subsequently, the control device 11A also calculates an average discharge interval 63 per unit time and an average discharge interval 64 per current print job (steps S416 and 417).
These processes are executed in order to reflect the print data added for forced ink droplet ejection in each information.

Thereafter, the control device 11A determines whether or not it is the last nozzle position (step S418), and while a negative result is obtained, proceeds to step S419 and changes the processing target to the next nozzle.
If a positive result is obtained in step S418, the control device 11A ends the nozzle clogging suppression process and proceeds to step S304.

<Effect of Embodiment 4>
If the printing system 1 according to the fourth embodiment is used, ink droplets are forcibly ejected at nozzle positions where print data does not appear for a long time, and the printing operation of the entire upstream machine or the entire downstream machine is forced. Can be avoided.
It should be noted that the processing function for suppressing clogging of a specific nozzle with few ejection opportunities in the present embodiment can be combined with the above-described first and second embodiments.

<Other embodiments>
Although the embodiments of the present invention have been described above, the technical scope of the present invention is not limited to the scope described in the above embodiments. It is clear from the description of the scope of the claims that various modifications or improvements added to the above embodiment are also included in the technical scope of the present invention.

  For example, in the above-described third and fourth embodiments, print data is assigned to an upstream machine or a downstream machine in image units, but may be combined with the second embodiment. That is, one page may be divided into partial pages, and print data corresponding to each nozzle position may be assigned to an upstream machine or a downstream machine for each image in the partial page. In this case, since one image is likely to appear across a plurality of partial pages, it is easy to assign print data in one page corresponding to one nozzle position to both the upstream machine and the downstream machine. As a result, with respect to the nozzle positions in the range where the image appears, the nozzles on the upstream machine side and the nozzles on the downstream machine side can secure a discharge opportunity, and the continuous non-discharge time or the average discharge interval can be shortened.

In the above-described embodiment, the process of executing the assignment destination of the print data constituting one page for each nozzle position is applied regardless of the print job, but the printer type can be stopped in units of one page. If the print job has a length that does not reach the downstream machine, the print data allocation destination determination process described above need not be executed for the print job.
Although not described in the above embodiment, if the time required for a page printed by the upstream machine to be conveyed to the downstream machine is less than the drying time, print data is sent to the downstream machine. It may not be assigned.

In the above-described embodiment, the determination of the print data assignment destination is executed by the control device 11A on the upstream side, but the determination may be executed by the control device 12A on the downstream side.
In addition, the determination is made by the higher-level apparatus managing the print job connected to the information processing apparatus or the printing system 1 in a separate housing from the first printing apparatus 11 as the upstream apparatus and the second printing apparatus 12 as the downstream apparatus. It may be executed with.

DESCRIPTION OF SYMBOLS 1 ... Printing system, 11 ... 1st printing apparatus (upstream machine), 11A, 12A ... Control apparatus, 11A1, 12A1 ... Data processing part, 11A2, 12A2 ... Mechanism control part, 11B, 12B ... Image output apparatus, 12 ... First 2 printing apparatus (downstream machine), 41 ... print job reception unit, 42 ... print data analysis unit, 43 ... assignment destination determination unit, 44 ... use history management unit, 51 ... alignment mark

Claims (13)

First forming means for forming an image by discharging droplets from a first discharge port to a recording material that is continuous in a strip shape;
Second forming means for forming an image by discharging droplets from the second discharge port to the recording material;
The print data in one page corresponding to each discharge position is converted into the first forming means or the first forming means based on the first use history of the first discharge port and the second use history of the second discharge port. An image forming system comprising: an assigning unit that assigns to the second forming unit.   The image forming system according to claim 1, wherein the allocating unit determines an allocation destination of the print data for each continuous partial area in one page.   The image forming system according to claim 2, wherein the assigning unit determines an assignment destination of the print data using a vector image as a processing unit.   The image forming system according to claim 2, wherein the assigning unit determines an assignment destination of the print data in units of line segments.   The image forming system according to claim 2, wherein the allocating unit determines an allocation destination of the print data in units of a plurality of regions that divide one page in the recording material conveyance direction.   The image according to claim 2, wherein the allocating unit allocates the print data of a part of the partial area corresponding to one ejection position to the first forming unit, and allocates the rest to the second forming unit. Forming system.   The image forming system according to claim 1, wherein the assigning unit determines an assignment destination of the print data based on each use frequency in the first use history and the second use history. The assigning means includes
If the usage frequency of the first usage history is lower than the usage frequency of the second usage history, the print data is assigned to the first forming means;
When the usage frequency of the second usage history is lower than the usage frequency of the first usage history, the print data is assigned to the second forming unit;
The image forming system according to claim 7. The assigning means includes
For each of the first forming means and the second forming means, it was determined whether or not the corresponding usage frequency was lower than a predetermined threshold value, and a determination result that the frequency was lower than the threshold value was obtained. 8. The image forming system according to claim 7, wherein the print data allocation destination is determined by giving priority to a forming unit positioned upstream with respect to a conveyance direction of the recording material.   The image forming system according to claim 1, wherein the allocating unit determines an allocation destination of the print data based on each non-use period in the first usage history and the second usage history. The assigning means includes
For each of the first forming means and the second forming means, it is determined whether or not the corresponding non-use period exceeds a predetermined threshold value, and a determination result that the threshold value is exceeded is obtained. The image forming system according to claim 10, wherein the print data allocation destination is determined with priority given to a forming unit positioned upstream with respect to a conveyance direction of the recording material.   The image forming system according to claim 11, wherein the threshold value is designated by a user within an allowable range of the non-use period. On the computer,
A function of reading a first usage history of the first ejection port for the first forming means for forming an image by ejecting liquid droplets from the first ejection port to a continuous recording material in a strip shape;
A function of reading a second usage history of the second ejection port with respect to a second forming unit that forms an image by ejecting droplets from the second ejection port to the recording material;
A function of assigning print data in one page corresponding to each discharge position to the first forming unit or the second forming unit based on the first use history and the second use history Program to let you.

Images