JP2013119176A - Device and method of image forming - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suppress a printing fault of a sheet.SOLUTION: This image forming device includes: a recording head including a plurality of nozzles for discharging liquid droplets to a recording medium; a detection means for detecting discharge abnormalities of the nozzles based on an image formed of the liquid droplets discharged from the nozzles; a data accumulation means for accumulating data regarding the discharge abnormalities of the nozzles in which the discharge abnormalities are detected by the detection means; a discharge disabling means for matching data regarding a printing job to the data accumulated in the data accumulation means regarding the discharge abnormalities of the nozzles in which the discharge abnormalities are detected, and for disabling the discharge of the nozzles in which the discharge abnormalities occur during the printing of the printing job in advance; and a complementing means for complementing image defects caused by the nozzles which are disabled by the discharge disabling means.

Description

  The present invention relates to an image forming apparatus and an image forming method.

  There is an ink jet recording apparatus that forms an image by ejecting liquid droplets from a nozzle of a recording head onto a recording medium such as paper. In this type of ink jet recording apparatus, the number of ejections is counted after enabling the ejection abnormal nozzles to be ejected by a recovery operation, and when the number of ejections reaches a specified value, the nozzles are made unemitted (use the nozzles). No) There is an ink jet recording apparatus that performs complementary processing with adjacent nozzles (for example, Patent Document 1).

  However, in this inkjet recording apparatus, all nozzles whose number of ejections has reached a specified value are made undischarged regardless of the print job information such as the number of printed sheets, so that the burden of complementary processing increases and printing defects may occur. There is.

JP 2007-118446 A

  In view of the above facts, an object of the present invention is to suppress paper printing defects.

  The image forming apparatus according to claim 1, wherein a discharge error of the nozzle is detected from a recording head including a plurality of nozzles that discharge droplets to a recording medium and an image formed by droplets discharged from each of the nozzles. Detecting means for detecting, data storing means for storing data relating to ejection abnormalities of nozzles for which ejection abnormality has been detected by the detecting means, data relating to print jobs, and detecting the ejection abnormalities accumulated in the data accumulating means The discharge nozzle is compared with the data relating to the discharge abnormality of the nozzle, and the discharge failure means that discharges the nozzle that causes discharge abnormality during printing of the print job in advance, and is discharged by the discharge failure means. Supplementary means for complementing image defects due to the nozzles.

  In the image forming apparatus according to the first aspect, the data relating to the ejection abnormality for each nozzle detected by the detection unit is stored in the data storage unit. In addition, by collating the data related to the print job with the data stored in the data storage means, the nozzle that becomes abnormally discharged during the print job is specified, and the nozzle is made undischarged in advance and undischarged. The completed nozzle is complemented by a complementing means. As a result, the nozzles in which ejection abnormalities are reproduced are undischarged, and all the non-discharge nozzles are complementarily processed, so that printing defects can be suppressed without wasting the recording medium.

  The image forming apparatus according to claim 2, wherein the discharge failure unit is configured until the droplet discharge amount of the nozzle calculated from the image data related to the print job becomes a discharge error due to the data related to the discharge error. When the amount is larger than the droplet discharge amount of the nozzle, the nozzle is made undischarged in advance.

  The image forming apparatus according to claim 2, wherein a droplet discharge amount discharged from each nozzle is calculated based on dot data created from image data relating to a print job, and the droplet discharge amount is data relating to discharge abnormality. The nozzles that are larger than the amount of droplets discharged until the ejection abnormality is caused to become undischarged in advance.

  In the image forming apparatus according to claim 3, the timing at which the nozzle in which the ejection abnormality is detected is undischarged by the non-discharge unit is before the start of printing of the print job.

  In the image forming apparatus according to claim 3, the nozzles that cause ejection abnormalities are made undischarged before the start of printing of the print job, so that complementation by adjacent nozzles is performed immediately after the start of printing, and the recording medium is not wasted. In addition, printing defects can be suppressed.

  The image forming apparatus according to claim 4, wherein the timing at which the nozzles in which the ejection abnormality is detected is ejected by the ejection failure unit is after the start of printing of the print job and before the nozzles have malfunctioned. The image defect is complemented by the complementing means at the timing when the nozzle is made undischarged.

  In the image forming apparatus according to claim 4, the data related to the print job is collated with the data stored in the data storage unit, and after the print job starts printing, the nozzle that causes ejection abnormality during printing of the print job, In addition, before the nozzle becomes abnormal in discharge, the nozzle is made non-dischargeable. For example, for the nozzles for which the number of prints is N until the ejection abnormality is caused by the data relating to the ejection abnormality, the nozzle is set to be undischarged when the printing of the (N-1) th sheet is completed.

  In addition, the complementing process is performed at the timing when the nozzle is undischarged. This makes it possible to perform nozzle ejection failure and complement processing before the nozzle becomes abnormal in ejection, and suppress the occurrence of printing defects. Further, by using the nozzle until an abnormality occurs, it is possible to prevent the abnormal discharge nozzle from solidifying.

  6. The image forming apparatus according to claim 5, wherein the discharge failure unit includes a nozzle until the number of discharges of the nozzle calculated from the image data related to the print job becomes a discharge error due to the data related to the discharge error. When the number of ejections is greater than the number of ejections, the nozzles are discharged in advance.

  In the image forming apparatus according to claim 5, the number of ejections to be ejected from each nozzle is calculated based on dot data created from the image data relating to the print job, and the ejection number is determined as ejection abnormality due to data relating to ejection abnormality. The nozzles that are larger than the number of discharges until the discharge become undischarged in advance.

  The image forming apparatus according to claim 6, wherein the discharge failure unit sets the nozzle in advance when the number of prints related to a print job is larger than the number of prints until the discharge abnormality is caused by the data related to the discharge abnormality. Become unemitted.

  7. The image forming apparatus according to claim 6, wherein the number of prints related to the print job is collated with the number of prints until the nozzle is abnormally discharged due to data relating to discharge abnormality, and the number of prints related to the print job is larger. Make it unemitted in advance. As a result, the amount of data to be managed can be reduced compared to the case of managing the discharge droplet amount or the discharge frequency of all the nozzles.

  The image forming apparatus according to claim 7, wherein the discharge failure unit includes at least one of a droplet discharge amount, a discharge number, and a print number of the nozzle calculated from image data relating to a print job, the discharge abnormality. When there is more than the droplet discharge amount, the number of discharges, or the number of prints of the nozzle until the discharge abnormality occurs according to the data relating to the above, the nozzle is made to discharge in advance.

  The image forming apparatus according to claim 7, wherein at least one of the three parameters of the droplet discharge amount, the number of discharges, and the number of printed sheets is a droplet discharge of a nozzle until a discharge abnormality occurs due to data related to the discharge abnormality. When the amount, the number of times of ejection, or the number of printed sheets is exceeded, the nozzle is made undischarged in advance. Thus, the nozzle can be reliably discharged before an abnormal discharge occurs.

  The image forming apparatus according to claim 8, wherein the detection unit detects whether droplets are ejected from the nozzles during printing of a print job.

  In the image forming apparatus according to the eighth aspect, it is detected whether or not liquid droplets are ejected due to nozzle clogging or the like during printing of the print job. Here, if it is determined that there is a discharge abnormality, data relating to the discharge abnormality is stored in the data storage means.

  The image forming apparatus according to claim 9, wherein the detection unit detects whether a landing position of a droplet discharged from the nozzle during printing of a print job is within a specified range.

  In the image forming apparatus according to the ninth aspect, the droplet that has landed at a position outside the specified range during printing of the print job is detected by the detection unit, and data relating to the ejection abnormality is stored in the data storage unit.

  The image forming apparatus according to claim 10, wherein the detection unit detects whether a landing diameter of a droplet discharged from the nozzle during printing of a print job is within a specified range.

  In the image forming apparatus according to claim 10, a large droplet or a small droplet outside the specified range is detected by the detection unit during printing of the print job, and data relating to the ejection abnormality is accumulated in the data accumulation unit. . Thereby, the nozzle which discharges the ink of the landing diameter which remove | deviated from the regulation range can be made to discharge in advance, and a printing defect can be suppressed.

  The image forming apparatus according to claim 11, wherein when the nozzles to be discharged by the discharger are close to each other, the droplet discharge amount of the nozzles calculated from the image data relating to the print job is greater. A large number of nozzles are discharged before the start of printing.

  In the image forming apparatus according to claim 11, when the nozzles to be undischarged by the non-discharge unit are close to each other, the non-discharge of some of the nozzles is canceled, so that the burden of the complementary processing by the complementary unit Can be reduced. For example, when complementation is performed by a nozzle adjacent to the nozzle to be discharged, if the nozzle to be discharged is close, the amount of liquid droplets discharged by the adjacent nozzle increases and the burden of the complementary processing increases. By canceling the non-discharge of the nozzles of the part, it is possible to reduce the burden due to the complementary processing of the adjacent nozzles.

  Also, by canceling the non-discharge of nozzles with a larger droplet discharge amount calculated from the image data related to the print job, it is possible to complement the adjacent nozzles rather than canceling the discharge failure of nozzles with a lower droplet discharge amount. The burden of processing can be reduced.

  The image forming apparatus according to claim 12, wherein when the nozzles to be discharged by the discharger are close to each other, droplet discharge until the nozzle discharge abnormality is caused by the data relating to the discharge abnormality. The ejection failure of the nozzle having a larger amount is canceled before printing is started.

  In the image forming apparatus according to claim 12, when the nozzle to be undischarged by the non-discharge unit is in proximity, the data relating to the discharge abnormality stored in the data storage unit is referred to and the discharge abnormality of the nozzle is determined. The ejection failure of the nozzle having a larger droplet discharge amount until the start is canceled before printing is started. As a result, the burden due to the complementary processing can be reduced as compared with the case where the ejection failure of the nozzle with a smaller droplet ejection amount until the ejection failure of the nozzle is canceled.

  According to a thirteenth aspect of the present invention, when the number of the nozzles to be discharged by the discharger becomes equal to or larger than a predetermined value, the image forming apparatus notifies before starting printing.

  In the image shape apparatus according to the thirteenth aspect, the user is notified by an alarm or the like that the number of nozzles to be discharged becomes a predetermined value or more, and is urged to divide the print job. As a result, it is possible to suppress the occurrence of printing defects due to the number of nozzles that become undischarged exceeding a predetermined value during printing.

  The image forming method according to claim 14, wherein an image forming apparatus having a recording head having a plurality of nozzles for discharging droplets to a recording medium reads an image formed by droplets discharged from each of the nozzles. A detection process for detecting an ejection abnormality of the nozzle, a data accumulation process for accumulating data relating to an ejection abnormality of a nozzle in which an ejection abnormality has been detected by the detection process, a data relating to a print job, and the data accumulation process. An undischarge process for comparing the data related to the discharge abnormality of the nozzle in which the discharge abnormality is detected, and discharging the nozzle that causes the discharge abnormality during printing of the print job in advance, and the non-discharge And a complementing step of complementing an image defect caused by the nozzle made undischarged by the step.

  In the image forming method according to the fourteenth aspect, the nozzles in which the ejection abnormality is reproduced are previously undischarged in the undischarge process, and all the undischarge nozzles are complemented in the complement process. Thereby, printing failure can be suppressed.

  Since the present invention is configured as described above, it is possible to suppress printing defects on paper.

1 is a schematic diagram illustrating an overall configuration of an ink jet recording apparatus according to a first embodiment. FIG. 3 is a plan view showing the arrangement of nozzles of the ink jet recording head according to the first embodiment. It is AA sectional drawing of FIG. FIG. 2 is a block diagram illustrating a system control unit of the ink jet recording apparatus according to the first embodiment. 3 is a flowchart illustrating a procedure for detecting an ejection abnormality by the inkjet recording apparatus according to the first embodiment. It is a flowchart which shows the procedure until the printing start by the inkjet recording device which concerns on 1st Embodiment. 6 is a table showing an example of an ejection droplet amount for each nozzle calculated from image data related to a print job and an ejection droplet amount for each nozzle until ejection abnormality occurs. (A) is explanatory drawing for demonstrating the state which does not perform a complementary process with respect to an undischarge nozzle, (B) is explanatory drawing for demonstrating the state which performed the complementary process with respect to an undischarge nozzle. is there. It is explanatory drawing for demonstrating the dot data made to discharge in the middle. It is a flowchart which shows the procedure until the printing start by the inkjet recording device which concerns on 2nd Embodiment. 6 is a table showing an example of an ejection droplet amount for each nozzle calculated from image data related to a print job and an ejection droplet amount for each nozzle until ejection abnormality occurs.

<Overall configuration of inkjet recording apparatus>
The overall configuration of the inkjet recording apparatus 10 according to the first embodiment of the present invention will be described with reference to the drawings. An inkjet recording apparatus 10 shown in FIG. 1 is a two-liquid aggregation type recording apparatus that forms an image using a colorant-containing ink and a treatment liquid containing a component that aggregates the ink.

  The ink jet recording apparatus 10 includes a paper feeding unit 12, a processing liquid application unit 14, an image forming unit 16, a drying unit 18, a fixing unit 20, and a paper discharge unit 22, and feeds paper P as a recording medium. An image is formed by sequentially conveying from the unit 12 to the paper discharge unit 22.

  The paper feed unit 12 includes a paper feed tray 24, and the paper P is stacked on the paper feed tray 24. Further, the paper feeding unit 12 is provided with a feeding mechanism (not shown), and the paper P stacked on the paper feeding tray 24 is taken out from the paper feeding tray 24 one by one and is rotatably disposed. To send. The paper P sent out to the paper supply drum 26 is conveyed along the outer peripheral surface of the paper supply drum 26 to the treatment liquid application unit 14. In the present embodiment, only one type of paper is stacked on the paper feed tray 24, but different sizes of paper P may be separately stacked. Further, the sheet form is not limited to the sheet-type configuration in which the sheet P is taken out one by one, and the roller-shaped long sheet P may be conveyed to form an image.

  The treatment liquid application unit 14 includes a treatment liquid application drum 28, and the paper P conveyed to the treatment liquid application unit 14 has a gripper 34 formed on the outer peripheral surface of the treatment liquid application drum 28 that is rotatably arranged. And is conveyed in the direction of the arrow in the figure. The grippers 34 are formed one by one at positions rotated 180 degrees in the circumferential direction of the treatment liquid application drum 28, and the paper P is attached to the outer peripheral surface of the treatment liquid application drum 28 with the end portion of the paper P interposed therebetween. Then transport. Further, other drums described later have the same configuration.

  The treatment liquid application unit 14 is provided with a treatment liquid application device 30 and a hot air generator 32 in order from the upstream side in the transport direction of the paper P along the outer peripheral surface of the treatment liquid application drum 28. The treatment liquid coating apparatus 30 is provided with a first roller 36 partially immersed in the treatment liquid, and a second roller 38 in contact with the first roller, and the second roller 38 is pressed against the paper P. The treatment liquid application drum 28 and the second roller 38 are rotated to apply the treatment liquid onto the paper P. In this embodiment, the processing liquid is applied by a roller, but the processing liquid may be applied to the paper P by other methods. For example, the treatment liquid may be applied by spraying.

  The sheet P coated with the treatment liquid passes under the hot air generator 32 provided above the treatment liquid application drum 28. At this time, the hot air is blown from the hot air generator 32 adjusted to a constant temperature to the paper P to dry the paper P. This suppresses the occurrence of the phenomenon that the color material floats.

  Next, the paper P is transported to the image forming unit 16 through the transport drum 40. The image forming unit 16 includes an image forming drum 42, holds the paper P transported from the transport drum 40, and transports it in the direction of the arrow in the figure. The image forming unit 16 is provided with a guide roller 44 and ink jet recording heads 46C, 46M, 46Y, and 46K in order from the downstream side in the transport direction of the paper P along the outer peripheral surface of the image forming drum 42.

  The guide roller 44 is in contact with the image forming drum 42. When the paper P passes between the image forming drum 42 and the guide roller 44, the paper P is pressed and brought into close contact with the image forming drum 42. The paper P that is in close contact with the image forming drum 42 by the guide roller 44 is conveyed below the ink jet recording heads 46C, 46M, 46Y, and 46K.

  The ink jet recording heads 46C, 46M, 46Y, and 46K correspond to four colors of ink of cyan, magenta, yellow, and black, respectively, and the ink jet recording head 46C, It is attached so that the bottom surfaces (nozzle surfaces) of 46M, 46Y, and 46K are parallel. In the following description, when the colors of the inkjet recording heads 46C, 46M, 46Y, and 46K are not specified, they are simply expressed as the inkjet recording head 46.

  The ink jet recording head 46 extends to the maximum width of the image forming area of the paper P in the axial direction of the image forming drum 42 and is a so-called full line head. Thereby, an image is formed without moving the inkjet recording head 46 in the width direction of the paper P.

  As shown in FIG. 2, a plurality of nozzles 72 are formed on the nozzle surface 46 </ b> A of the inkjet recording head 46. The nozzles 72 include nozzle rows that are formed at equal intervals in the width direction of the paper P up to the maximum width of the image forming area of the paper P, and six nozzle rows are formed at equal intervals in the transport direction of the paper P. Yes. The nozzle rows formed in the transport direction of the paper P are formed so as to be shifted by the pitch d in the width direction of the paper P as it goes downstream in the transport direction of the paper P.

  Here, addresses are assigned to all the nozzles 72. In the present embodiment, alphabets (A, B, C,...) Set in order from the left in the width direction of the paper P and numbers (1) set in order from the upstream side to the downstream side in the transport direction of the paper P. 2, 3,...) Assigns addresses to all the nozzles 72. For example, in the figure, the address of the lower left nozzle 72 is A1. Further, a serial number is assigned to each address in order from the address A1, and for example, the number of the address B1 is 7.

  As shown in FIG. 3, the nozzle 72 communicates with the pressure chamber 74. An ink supply path 76 is formed at the end of the pressure chamber 74, and the ink supplied from an ink tank (not shown) to the common flow path 78 flows through the ink supply path 76 and flows into the pressure chamber 74. Has been.

  The upper part of the pressure chamber 74 is closed by a diaphragm 73, and a piezoelectric element 80 is attached to the diaphragm 73. A common electrode 81 is disposed on the lower surface of the piezoelectric element 80, and an individual electrode 82 is disposed on the upper surface of the piezoelectric element 80. Here, when a voltage is applied between the common electrode 81 and the individual electrode 82, the piezoelectric element 80 is deformed, the diaphragm 73 is bent, and the pressure chamber 74 is contracted. In this way, the volume of the pressure chamber 74 is reduced, and the ink in the pressure chamber 74 is pushed out from the nozzle 72 to eject the ink. Further, after the ink is ejected, the application of the voltage to the individual electrode 82 is canceled, whereby the diaphragm 73 returns to its original shape, and the ink is supplied from the common channel 78 to the pressure chamber 74.

  In the present embodiment, the ink is ejected by changing the volume of the pressure chamber 74 using the piezoelectric element 80 such as a piezo element, but the ink may be ejected by other methods. For example, a thermal system in which ink is pushed out by generating bubbles using a heating element such as a heater and ejected from the nozzles 72 may be used.

  As shown in FIG. 1, when the paper P is conveyed to the image forming area directly below the ink jet recording head 46, the paper P is fed from the nozzles 72 of the respective ink jet recording heads 46C, 46M, 46Y, and 46K based on the image data. Ink is ejected to the image forming area where the treatment liquid is applied.

  Here, an example of a procedure for forming an image by ejecting ink from all the nozzles 72 to the paper P will be described with reference to FIG. When the leading end of the image forming area of the paper P is conveyed to just below the first nozzle row of the inkjet recording head 46, droplets are ejected from the first nozzle row. Next, ink is ejected from the first and second nozzle rows at the timing when the paper P is carried by one row in the carrying direction. For this reason, the ink ejected from the first and second nozzle rows has landed at the leading end of the image forming area of the paper P. That is, the ink ejected from the nozzles 72 of A1, A2, B1, B2,... Is landed in the width direction of the paper P in order from the end in the width direction of the paper P. Similarly, ink is ejected every time the paper P is conveyed by one row, and when ink is ejected from the sixth nozzle row to the leading end of the image forming area of the paper P, the width of the paper P is increased. Ink is landed at intervals of the pitch d. In this way, an image is formed. Further, the ink that has landed on the paper P reacts with the processing liquid, whereby the color material in the ink is aggregated and the bleeding is suppressed.

  In the present embodiment, the ink jet recording heads 46C, 46M, 46Y, and 46K are configured with four colors, but the ink color and the number of colors are not limited thereto. For example, six colors may be configured by adding inks such as light cyan and light magenta. Further, the order in which the inkjet recording heads 46C, 46M, 46Y, and 46K are arranged is not particularly limited.

  The paper P on which an image is formed as described above is conveyed to the drying unit 18 via the conveyance drum 48. The drying unit 18 includes a drying drum 50, holds the paper P conveyed to the conveyance drum 48, and conveys it in the direction of the arrow in the figure. A heater 50 </ b> A is attached to the inside of the drying drum 50, and two hot air generators 50 </ b> B are provided along the outer peripheral surface of the drying drum 50 on the outside of the drying drum 50.

  The paper P held on the drying drum 50 is heated by the heater 50A, and is dried by the hot air blown to the paper P from the hot air generator 50B. Note that another heated member may be used instead of the heater 50A, and a device for drying with radiant heat such as a halogen heater may be used instead of the hot air generator 50B. Moreover, the structure which can change suitably the temperature of heater 50A and the warm air generator 50B with the kind of ink to be used or the kind of paper P may be sufficient.

  The paper P dried by the drying unit 18 is conveyed to the fixing unit 20 through the conveyance drum 52. The fixing unit 20 includes a fixing drum 54, holds the sheet P conveyed to the conveying drum 52, and conveys it in the direction of the arrow in the figure. In the fixing unit 20, a first fixing roller 56, a second fixing roller 58, and a line sensor 60 as a detection unit are provided in order from the downstream side in the conveyance direction of the paper P.

  The first fixing roller 56 and the second fixing roller 58 are in contact with the fixing drum 54 and are heated by a heating unit (not shown). The temperature of the first fixing roller 56 is set lower than that of the second fixing roller 58. Here, when the sheet P held on the fixing drum 54 passes between the first fixing roller 56 and the second fixing roller 58 and the fixing drum 54, the sheet P is heated by the first fixing roller 56 and the second fixing roller 58. At the same time, it is pressed against the fixing drum 54 and subjected to fixing processing.

  The sheet P on which the fixing process has been performed by the first fixing roller 56 and the second fixing roller 58 is conveyed below the line sensor 60. The line sensor 60 includes a CCD image sensor (not shown) provided opposite to the fixing drum 54 and arranged in the axial direction of the fixing drum 54. The CCD image sensor has a larger number of pixels than the number of nozzles 72. Further, the line sensor 60 extends in a direction intersecting the conveyance direction of the paper P, for example, a direction orthogonal thereto, and has substantially the same length as the width of the paper P.

  Here, when the paper P conveyed to the fixing drum 54 passes under the line sensor 60, a CCD image sensor (not shown) provided in the line sensor 60 applies ink landed on the image forming area of the paper P to the paper P. One row is detected in the conveyance direction, and an ejection abnormality of the nozzle 72 is detected. The line sensor 60 is not limited to the configuration including the CCD image sensor, and may be a configuration including a CMOS image sensor, for example.

  The paper P that has passed through the line sensor 60 is conveyed to the paper discharge unit 22. The paper discharge unit 22 is provided with a discharge roller 62, and feeds the paper P conveyed to the fixing drum 54 to the discharge belt 64. The paper P on the discharge belt 64 is discharged to the discharge tray 66.

  In the inkjet recording apparatus 10 according to the present embodiment, the line sensor 60 is configured to detect the image related to the print job formed on the paper P one by one. However, the line sensor 60 is dedicated to the image separately from the image related to the print job. A test pattern may be formed and detected. In this case, by forming a test pattern that can be easily detected by the CCD image sensor, the detection accuracy of the ejection abnormality by the line sensor 60 is improved.

  Further, since an arbitrary pattern can be formed in the test pattern, the ink droplets ejected from the respective nozzles 72 are landed so as not to overlap in the width direction of the paper P, and the landed ink is detected by the line sensor 60 and the nozzles. The type of discharge abnormality 72 may be determined. For example, when the landed ink is displaced in the width direction of the paper P with respect to the test pattern line, this ink is detected, and it can be determined that the nozzle 72 that ejected the ink droplet is an abnormal ejection nozzle due to misalignment. Further, when the landing diameter of the ink droplet is larger than the specified range and overlaps with the ink adjacent in the width direction of the paper P, this abnormal ink is detected, and the nozzle 72 that ejects the ink droplet is ejected abnormally due to the abnormal landing diameter. Can be determined.

  Further, a configuration may be adopted in which ink is directly ejected onto the image forming drum 42 to form a test pattern and detected by a line sensor having the same configuration as the line sensor 60. In this case, a line sensor is provided along the outer periphery of the image forming drum 42 on the downstream side in the transport direction from the ink jet recording head 46, and the test pattern on the image forming drum 42 is detected, so that the nozzle 72 is used without using the paper P. Discharge abnormality can be detected. A separate cleaning member may be provided along the outer periphery of the image forming drum 42 to scrape off the test pattern formed on the image forming drum 42. The ink jet recording head 46 and the line sensor 60 are connected to the system control unit 11.

<System controller>
Next, the system control unit 11 of the inkjet recording apparatus 10 according to the present embodiment will be described. As shown in FIG. 4, the system control unit 11 includes a data storage unit 86, a drive unit 88, an image memory 84, a dot data creation unit 90, a control device 92, and a mask processing unit 94. In addition, a host computer 96, a line sensor 60, and an ink jet recording head 46 are connected to the system control unit 11.

  The dot data creation unit 90 creates a dot pattern that reproduces the image data based on the image data relating to the print job. Here, the dot data is created including the shade and color of the image. That is, dot data is created so as to increase the landing diameter of ink in a dark area, and dot data is generated so as to decrease the landing diameter of ink in a light area. Note that when the ink landing diameter is increased, the amount of ejected ink droplets is increased, and when the ink landing diameter is decreased, the appropriate amount of ink ejected is decreased.

  The drive unit 88 drives a motor that drives the transport drums 40, 48, 52, the paper feed drum 26, the discharge roller 62, and the like according to a command from the control device 92. The image memory 84 temporarily stores image data relating to a print job, and temporarily stores the calculation results calculated by the calculation processing device of the control device 92.

  The data accumulating unit 86 accumulates data relating to ejection abnormality for each nozzle 72 detected by the line sensor 60. Here, a procedure for accumulating data will be described. As shown in FIG. 5, in step 100, each CCD image sensor reads a print image on the paper P conveyed immediately below the line sensor 60. Next, in step 102, the read print image is compared with the image data relating to the print job.

  Next, in step 104, it is determined whether there is a discharge abnormality. Here, if there is a defect in the image read by the CCD image sensor as a result of comparison with the image data in step 102, it is determined that the ejection failure, landing position deviation, or landing diameter is outside the specified range, and the process proceeds to step 106. .

  In step 106, the address of the nozzle 72 having an ejection failure is determined from the missing image area. Next, in step 108, for the nozzle 72 at the address determined in step 106, the ejection droplet amount of the ink ejected by the nozzle 72 is sent to the control device 92.

  Finally, in step 110, the control device 92 acquires the nozzle 72 data accumulated in the data accumulation unit 86, and updates the accumulated data by adding the data relating to the ejection abnormality sent in step 108. The updated data is stored in the data storage unit 86. The data sent to the data storage unit 86 may include the number of ink ejections and the number of printed sheets. Further, the detection of ejection abnormality in step 104 may include ejection abnormality in which ink was not ejected due to clogging of the nozzle 72 or the like.

  The control device 92 in FIG. 4 is configured by an arithmetic processing device such as a CPU, and controls the entire inkjet recording apparatus 10. Specifically, the driving unit 88 is controlled to drive or takes out arbitrary image data from the image memory 84 and instructs the dot data creating unit 90 to create dot data.

  In addition, among the nozzles 72 that have abnormally discharged in the past, there are nozzles 72 that may reproduce the abnormal discharge. Therefore, such nozzles 72 are previously undischarged (the ink is not discharged from the nozzles 72). In order to suppress the occurrence of an ejection abnormality during printing of the print job, the control device 92 relates to the data relating to the ejection abnormality accumulated in the data accumulation unit 86 and the print job input to the host computer 96. The dot data created from the image data is collated, and it is determined for all the nozzles 72 whether the nozzles 72 are used or non-discharge nozzles before starting printing. This determination method will be described later.

  The mask processing unit 94 receives the address of the nozzle 72 to be discharged from the control device 92 and edits the dot data created by the dot data creation unit 90. For example, the dot data corresponding to the nozzle 72 to be discharged is deleted, and the dot data is edited so that the landing diameter of the nozzle 72 adjacent to the nozzle 72 to be discharged becomes large.

<Printing Procedure of First Embodiment>
Next, a printing procedure of a program executed by the control unit 92 of the inkjet recording apparatus 10 according to the present embodiment will be described along the flowchart of FIG.

  First, in step 200, when the user inputs print job information to the host computer 96, the print job information is sent from the host computer 96 to the control device 92 (see FIG. 4). Here, the print job information includes image data to be printed, the number of prints, print quality, print speed, and the like.

  The control device 92 temporarily stores the image data relating to the print job received from the host computer 96 in step 200 in the image memory 84 and instructs the dot data creation unit 90 to create dot data (step 102). Alternatively, in step 202, the dot data creation unit 90 is instructed to create dot data directly without saving it in the image memory 84.

  Next, in step 204 of FIG. 6, the arithmetic processing unit of the control device 92 substitutes 1 for the variable i. Thereafter, in step 206, the ejection droplet amount Vi of ink ejected by the nozzle 72 of the variable i during the print job is calculated. Here, since i = 1, the ejection droplet amount V1 of the ink ejected by the nozzle 72 of the number 1, that is, the nozzle 72 of the address A1, when printing the print job is calculated.

  The procedure for calculating the ejection droplet amount V1 is to calculate the ejection droplet amount ejected by the nozzle 72 at the address A1 per sheet based on the dot data created by the dot data creation unit 90 first. The dot data can be set in three stages for the amount of ejected droplets of one dot so as to correspond to the density of the image data, and the ink landing diameter can be varied. For this reason, when calculating the amount of ejected droplets ejected by the nozzle 72 at address A1 per sheet, the number of dots is calculated for each of the three ejected droplet amounts and multiplied by the amount of ejected droplets per dot. . In this embodiment, the amount of ejected droplets of one dot can be set in three stages. However, for example, a configuration that can be set in different stages such as two stages may be adopted.

  The nozzle of the variable i indicating the address in the print job by multiplying the number of prints related to the print job to the ejection droplet amount per sheet of the nozzle 72 of the variable i indicating the address calculated as described above. An ejection droplet amount Vi ejected from 72 is calculated. The above example is a calculation method for printing a plurality of the same images. When printing different images, the dot data is created for all the images, and then the ejection droplet amount of each nozzle 72 is determined. calculate.

  Next, in step 208, the control device 92 acquires from the data storage unit 86 an average value VAi of the ejection droplet amount until the ejection failure of the nozzle 72 of number i occurs (see FIG. 4). As described above, the data storage unit 86 stores the data related to the discharge abnormality related to the discharge abnormality for each nozzle 72, and acquires VAi from the data related to the discharge abnormality.

  Here, normally, the average value VAi of the ejected droplet amount ejected until the ejection abnormality is determined is acquired, but the maximum value VAimax or the minimum value VAimin of the ejected droplet amount ejected until the ejection abnormality is determined. You may set to acquire. Note that the maximum value VAimax here is the ejection droplet amount of the nozzle 72 with the number i in the print job in which the most ink is ejected until the nozzle 72 with the number i is determined to be abnormal in the past print job. That is.

  Next, in step 210, Vi and VAi are collated. If VAi is greater than or equal to Vi, the process proceeds to step 214. If VAi is less than or equal to Vi, the process proceeds to step 212 and nozzle No. 72 with the number i is discharged. Register to the nozzle.

  Here, when the nozzle 72 with the number i has never been determined to be abnormal in discharge in the past, the data storage unit 86 does not store data relating to the abnormal discharge with respect to the nozzle 72 with the number i, and VAi is ∞. It is said that. Therefore, in step 210, it is determined that VAi is equal to or greater than Vi, and the process proceeds to step 114.

  In step 214, it is determined whether it is the last nozzle 72 or not. If the nozzle 72 with the number i is not the last nozzle 72, the process proceeds to step 216. In step 216, 1 is added to i, and the process proceeds to step 206. That is, i = i + 1, and the processing from step 206 to step 216 is performed for the nozzle 72 of number i + 1, that is, when the previous address is A1, the nozzle 72 of address A2.

  In this way, while adding 1 to i, steps 206 to 214 are repeated until the last nozzle 72 is reached. For example, when i = 7, the determination is made for the nozzle 72 at address B1. When i = 13, the determination is made for the nozzle 72 at address C1. This is repeated until the last nozzle 72, that is, the nozzle 72 at the upper right address in FIG.

  Here, FIG. 7 shows the average value VAi, maximum value VAimax, minimum value VAimin, and images related to the print job until it is determined that there is a discharge abnormality for each nozzle 72 stored in the data storage unit 86. The discharge droplet amount Vi for each nozzle 72 calculated from the data is described, and the flow from step 206 to step 216 in FIG. 6 will be described based on the data in FIG. Note that the numerical values described in FIG. 7 are the total ejection droplet amounts related to the print job when the ejection droplet amount when ink is ejected onto all the rows of one sheet P is 100.

  When i = 1, the ejection droplet amount V1 of the nozzle 72 at the address A1 calculated from the image data related to the print job in step 206 is 453, and VA1 acquired from the data storage unit 86 in step 208 is 652. It has become. Therefore, in step 210, V1 <VA1, and the nozzle 72 at the address A1 is not discharged.

  Similarly, the nozzle 72 of the address A2 and the nozzle 72 of the address A3 are not discharged because V2 <VA2 and V3 <VA3. Next, since the nozzle 72 at the address A4 has not been determined to be ejection abnormality during a past print job, data relating to ejection abnormality is not accumulated in the data accumulation unit 86. For this reason, the nozzle 72 of the address A4 is not discharged.

  The nozzle 72 of the address A6 has VA6 of 543 with respect to V6 of 1080. Therefore, in step 214 of FIG. 6, V6> VA6 is established, and the process proceeds to step 212 to be registered in the discharge failure nozzle. In this way, it is determined whether all nozzles 72 should be discharged. When the determination in step 210 is completed for the last nozzle 72, the process proceeds from step 214 to step 218. In the case where the determination is made based on VAimin, in FIG. 7, the nozzle 72 at address A1, the nozzle 72 at address A6, and the nozzle 72 at address B2 are registered as non-discharge nozzles.

  In step 218, dot data is edited by the mask processing unit 94 (see FIG. 4). Specifically, the dot data corresponding to the nozzle 72 of the address A6 registered in the non-discharge nozzle is deleted, and instead, the discharge droplet amount of the nozzles 72 of the addresses A5 and B1 adjacent to the nozzle 72 of the address A6 is large. Edit the dot data so that

  By editing the dot data in this way, as shown in FIG. 8A, if the dot data corresponding to the nozzle 72 at address A6 is simply deleted, the area 72 where the nozzle 72 at address A6 was scheduled to be ejected is displayed. Although ink is not ejected, it stands out, but as shown in FIG. 8B, by increasing the ejection amount of ink ejected from the nozzles 72 of the addresses A5 and B1 adjacent to the nozzle 72 of the address A6, The area T is filled by increasing the landing diameter. In FIG. 8A, for convenience of explanation, the inks ejected from the nozzles 72 are arranged without overlapping, but the inks actually overlap.

  Next, printing is started in step 220 of FIG. Here, ink is ejected onto the paper P based on the dot data edited in step 218 to form an image. As described above, since the ejection failure of the nozzle 72 and the complementary setting by the adjacent nozzle 72 are performed before the printing of the print job is started, the ejection failure of the nozzle 72 occurs during the print job. Can be suppressed.

In the present embodiment, the ink ejection amount Vi for each nozzle 72 calculated from the image data relating to the print job and the nozzles 72 until the ejection abnormality is caused by the data relating to the ejection abnormality accumulated in the data accumulation unit 86. Although the configuration is such that the average value VAi of the discharge amount of each ink is collated, another index may be used. For example, the number of ejections for each nozzle 72 calculated from the image data relating to the print job is collated with the number of ejections for each nozzle 72 until the ejection abnormality is caused by the data relating to ejection abnormality accumulated in the data storage unit 86. It may be a configuration. In this case, the calculation can be easily performed as compared with the case of collating the ejection droplet amount. In addition, the configuration may be such that the number of prints related to the print job is compared with the number of prints for each nozzle 72 until the discharge abnormality is caused by the data related to the discharge abnormality stored in the data storage unit 86. Furthermore, the number of prints per nozzle 72, the number of discharges, until any of the number of prints, the number of discharges, and the proper discharge amount related to the print job becomes a discharge abnormality due to the data related to the discharge abnormality stored in the data storage unit 86, and It is good also as a structure which makes the nozzle 72 which became larger than the suitable discharge amount undischarged.

  In this embodiment, the dot data edited in step 218 in FIG. 6 is applied from immediately after the start of printing of the print job. However, even before printing, the dot data before editing is used. Good. In this case, the dot data edited in step 118 may be temporarily stored, and the edited dot data may be applied before the total ejection droplet amount of the non-ejecting nozzle reaches VAi. For example, as shown in FIG. 9, in the region A from when printing of the print job is started until the cumulative amount of ink ejected from the nozzle 72 at address A6 reaches 493, which is 50 less than 543, the dot before editing In the region B where the cumulative amount of ejected droplets is larger than 493 using the data, the dot data corresponding to the nozzle 72 at the address A6 is deleted by applying the edited dot data, and the nozzles at the addresses A5 and B1 are used instead. The amount of ejected droplets of ink 72 is increased. Thereby, since the discharge droplet amount of the nozzle 72 to complement can be reduced, the burden of the complementing process can be reduced.

  Further, when the dot data is edited in step 218, the dot data corresponding to the nozzle 72 of the address A6 is left without being deleted until the accumulated droplet amount reaches 493, and the accumulated appropriate amount exceeds 493. In such a portion, the dot data may be edited so that the dot data corresponding to the nozzle 72 of the address A6 is deleted and the complementing process is performed. In this case, the dot data is not changed during the print job.

  In the present embodiment, printing is performed even when the number of discharge failure nozzles increases. However, when editing dot data in step 218 in FIG. A configuration may be adopted in which the user is notified that printing has exceeded the specified value before starting printing. As a notification method, it may be displayed on a monitor (not shown) provided in the host computer 96, or a display means (not shown) provided in the inkjet recording apparatus 10 itself or an alarm may be sounded to notify the user. As a result, the user can be urged to change the number of prints input to the print job, and the burden of the supplement processing can be reduced. Further, it is possible to suppress the occurrence of printing defects due to an increase in the number of non-discharge nozzles.

<Printing Procedure of Second Embodiment>
Next, an ink jet recording apparatus according to a second embodiment of the present invention will be described. In addition, the thing of the same structure as 1st Embodiment attaches | subjects the same code | symbol, and abbreviate | omits suitably and demonstrates.

  The configuration of the inkjet recording apparatus 13 according to the second embodiment is the same as the configuration of the inkjet recording apparatus 10 according to the first embodiment shown in FIGS. The printing procedure is partially different from that of the inkjet recording apparatus 10 according to the first embodiment. The printing procedure of the inkjet recording apparatus 10 according to the present embodiment will be described along the flowchart shown in FIG.

  In step 300, the processing from step 200 to step 214 in FIG. 6 (processing A) is performed. Since the specific contents are as described above, they are omitted. Next, in step 302, the arithmetic processing unit of the control device 92 substitutes 1 for the variable i (see FIG. 4).

  In step 304, it is determined whether there are a plurality of non-discharge nozzles within the three nozzles adjacent to the nozzle 72 of number i. When i = 1, if there are a plurality of non-discharge nozzles within 3 nozzles adjacent to the nozzle 72 of the address A1, the process proceeds to step 306.

  In step 306, the non-discharge of the nozzle 72 that discharges the largest amount of ink during a print job is canceled. Canceling the discharge failure means releasing the registration of discharge failure nozzles performed in step 212 in FIG. Thereafter, the process proceeds to step 304 again, and if there are not a plurality of discharge failure nozzles within three nozzles adjacent to the nozzle of number i, the process proceeds to step 308.

  In step 308, it is determined whether it is the last nozzle. When i = 1, since the nozzle 72 at the address A1 is not the last nozzle, the process proceeds to step 310, 1 is added to i, i = 2 is set, and the process proceeds to step 304.

  The procedure from step 302 to step 308 will be described with reference to the data shown in FIG. 11. When i = 1, it is determined whether there are a plurality of discharge failure nozzles within 3 nozzles adjacent to the nozzle 72 at address A1. . Here, the three nozzles adjacent to the nozzle of the address A1 become the nozzles 72 of the addresses A1 to A4. However, since there is no discharge failure nozzle, the process proceeds to step 310 and 1 is added to i (see FIG. 10). .

  Similarly, for the nozzle 72 at the address A2, there is no non-discharge nozzle within three adjacent nozzles. Next, the nozzles within three nozzles adjacent to the nozzle 72 of the address A3 become the nozzles 72 of the addresses A1 to A6. Here, the average value VA6 (= 543) of the ejection droplet amount until it is determined that the ejection failure of the nozzle 72 at the address A6 is the ejection droplet amount V6 of the nozzle 72 at the address A6 calculated from the image data related to the print job. Since it is smaller than (= 1080), the nozzle 72 of the address A6 becomes an undischarge nozzle. However, since the nozzles 72 having addresses A1 to A6 do not have a plurality of discharge failure nozzles, the process proceeds to step 310 through step 308 in FIG.

  Similarly, step 304 to step 310 are repeated, and when i = 11, it is determined whether there are a plurality of non-discharge nozzles within 3 nozzles adjacent to the nozzle 72 of the address B5 shown in FIG. Since the C2 nozzle 72 is an ejection failure nozzle, it is determined that there are a plurality of ejection failure nozzles, and the process proceeds to step 306.

  In step 306, the non-ejection of the nozzle 72 having a larger ejection droplet amount Vi calculated from the image data related to the print job is canceled from the nozzles 72 of the addresses C1 and C2. Since the discharge droplet amount V14 (1371) of the nozzle 72 at the address C2 is larger than the discharge droplet amount V13 (1206) of the nozzle 72 at the address C1, the discharge failure of the nozzle 72 at the address C2 is canceled.

  Similarly, when i = 12, within the three nozzles adjacent to the nozzle 72 at address B6, there are three non-discharge nozzles at addresses C1 to C3. Here, since the nozzle 72 at the address C2 has already been released from the discharge failure, the nozzles 72 at the addresses C1 and C3 are recognized as the discharge failure nozzle.

  Further, when the discharge droplet amount V13 (1206) of the nozzle 72 at address C1 is compared with the discharge droplet amount V15 (967) of the nozzle 72 at address C3, the discharge droplet amount V13 of the nozzle 72 at address C1 is larger. The discharge failure of the nozzle 72 at the address C1 is canceled.

  The discharge failure of the nozzle 72 at address C5 is also released by the same procedure. After repeating this and determining the last nozzle 72, the process proceeds to step 312 in FIG. 10 to edit the dot data.

  In the dot data editing, among the nozzles 72 registered as non-discharge nozzles in step 212 of FIG. 6, the nozzles 72 (nozzles such as addresses C1, C2, and C5) whose discharge was canceled in step 206 of FIG. 72), the dot data corresponding to the nozzle 72 (nozzle 72 of address A6, C3, etc.) for which the discharge failure has not been canceled is deleted. Further, the dot data is changed so that the amount of ejected droplets of the nozzle 72 adjacent to the non-discharge nozzle is increased. When the editing of the dot data is completed, printing of the print job is started based on the edited dot data (step 314).

  In the ink jet recording apparatus 13 according to the present embodiment, the non-discharge of the nozzle 72 having the largest ejection droplet amount Vi is canceled in step 306 in FIG. However, conversely, it may be configured to cancel the non-discharge of the nozzle 72 having the smallest ejection droplet amount Vi. Also in this case, it is possible to reduce the burden of the complementary processing by canceling the non-discharge of some of the nozzles 72.

  Further, in step 306, it is possible to cancel the discharge failure of the nozzle 72 having the largest average value VAi of the ejection droplet amount until the ejection abnormality occurs, instead of the nozzle 72 having a large Vi. In this case, as compared with other non-discharge nozzles, the nozzles 72 that have been released from non-discharge can discharge more ink before ejection failure, thereby reducing the burden of complementary processing.

  Further, in this embodiment, it is determined in step 304 whether there are a plurality of discharge failure nozzles within 3 nozzles adjacent to the nozzle 72 of number i. However, the number is not limited to 3 nozzles, for example, within 5 adjacent nozzles. It may be determined whether there are a plurality of non-discharge nozzles.

  The first and second embodiments of the present invention have been described above. However, the present invention is not limited to such embodiments, and the first and second embodiments may be used in combination. Needless to say, the present invention can be implemented in various forms without departing from the scope of the invention. For example, the present invention is not limited to a single-pass inkjet recording apparatus, and may be applied to a so-called shuttle scan inkjet recording apparatus that performs printing while repeatedly moving a recording head. In FIG. 1, the drum such as the transport drum 40 has a structure capable of transporting two sheets of paper P per revolution (double cylinder), but has a structure capable of transporting only one sheet of paper P (1). (Double cylinder) or a structure capable of conveying three sheets (triple cylinder) may be used.

10 Inkjet recording device (image forming device)
13 Inkjet recording device (image forming device)
46 Inkjet recording head (recording head)
60 line sensor (detection means, detection process)
72 Nozzle 86 Data accumulation part (data accumulation means, data accumulation process)
92 Control device (non-discharge means, non-discharge process)
94 Mask processing unit (non-discharge means, complement means, non-discharge process, complement process)

Claims (14)

A recording head having a plurality of nozzles for discharging droplets onto a recording medium;
Detecting means for detecting an ejection abnormality of the nozzle from an image formed by droplets ejected from each of the nozzles;
Data accumulating means for accumulating data relating to ejection abnormality of the nozzle in which ejection abnormality is detected by the detection means;
The data relating to the print job is collated with the data relating to the ejection abnormality of the nozzle in which the ejection abnormality is detected, which is accumulated in the data accumulating unit, and the nozzles that cause the ejection abnormality during the printing of the print job are preliminarily determined. Non-emetic means for emesis,
Complementing means for complementing image defects caused by the nozzles made non-emitted by the non-ejecting means;
An image forming apparatus.   The non-discharge unit is configured such that the droplet discharge amount of the nozzle calculated from the image data related to the print job is larger than the droplet discharge amount of the nozzle until the discharge abnormality is caused by the data related to the discharge abnormality. The image forming apparatus according to claim 1, wherein the nozzle is undischarged in advance.   3. The image forming apparatus according to claim 1, wherein the timing at which the ejection failure of the nozzles in which the ejection abnormality has been detected is made before ejection of the print job is started. 4.   The timing at which the nozzles in which the ejection abnormality is detected by the ejection failure means is ejected after the start of printing of the print job and before the nozzle in which the ejection abnormality is detected becomes an ejection abnormality. The image forming apparatus according to claim 1, wherein an image defect is complemented by the complementing unit at a timing at which the detected nozzle is discharged.   When the number of ejections of the nozzle calculated from the image data relating to the print job is greater than the number of ejections of the nozzle until the ejection abnormality occurs due to the data relating to the ejection abnormality, The image forming apparatus according to claim 1, wherein the image forming apparatus is undischarged in advance.   The discharge failure means discharges the nozzle in advance when the number of prints related to a print job is larger than the number of prints until the discharge abnormality is caused by the data relating to the discharge abnormality. 5. The image forming apparatus according to claim 1.   The non-discharge unit is configured such that at least one of the droplet discharge amount, the number of discharges, and the number of prints calculated from the image data relating to the print job is a droplet discharge amount of the nozzle until an abnormal discharge occurs. 5. The image forming apparatus according to claim 1, wherein when the number of ejections is greater than the number of ejections or the number of printed sheets, the nozzle is undischarged in advance.   The image forming apparatus according to claim 1, wherein the detection unit detects whether droplets are ejected from the nozzle during printing of a print job.   The image forming apparatus according to claim 1, wherein the detection unit detects whether a landing position of a droplet discharged from the nozzle during printing of a print job is within a specified range.   The image forming apparatus according to claim 1, wherein the detection unit detects whether a landing diameter of a droplet discharged from the nozzle during printing of a print job is within a specified range.   When the nozzles that are made undischarged by the non-ejecting means are close to each other, the discharge of the nozzles having a larger droplet discharge amount for each nozzle calculated from the image data related to the print job is performed. The image forming apparatus according to claim 1, which is released before printing is started.   When the nozzles to be discharged by the discharger are close to each other, the discharge of the nozzles with a larger amount of liquid droplet discharge until the nozzle discharges abnormal due to the data related to the abnormal discharge is performed. The image forming apparatus according to claim 1, which is released before printing is started.   13. The image forming apparatus according to claim 1, wherein when the number of the nozzles to be discharged by the discharger becomes equal to or greater than a predetermined value, the image forming apparatus is notified before the start of printing. In an image forming apparatus having a recording head having a plurality of nozzles for discharging droplets to a recording medium,
A detection step of reading an image formed by droplets discharged from each of the nozzles to detect discharge abnormality of the nozzles;
A data accumulating step for accumulating data relating to ejection abnormality of the nozzle in which ejection abnormality is detected by the detection step;
The data relating to the print job and the data relating to the discharge abnormality of the nozzle in which the discharge abnormality has been detected accumulated in the data accumulation step are collated, and the nozzles that cause the discharge abnormality during the printing of the print job are determined in advance. An unemergence step for emesis,
A complementing step of complementing image defects caused by the nozzles made non-discharged by the non-ejecting step;
An image forming method comprising:

Images