JP2011201157A - Cleaning control method for liquid ejection device and liquid ejection device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a cleaning control method for a liquid ejection device in which a recoverable failing nozzle can be recovered while suppressing useless consumption of liquid droplets ejected from nozzles.SOLUTION: The liquid ejection device performs cleaning for solving dot omission when dot omission occurs with the presence of a failing nozzle that does not eject liquid droplets among a plurality of nozzles for ejection of liquid droplets. The liquid ejection device inspects the presence or absence of failing nozzles, and performs cleaning control of determining whether or not cleaning is necessary on the basis of the inspection result and failing nozzle information that is information on the failing nozzles stored beforehand. In the cleaning control, when cleaning is determined to be necessary as a result of determining whether or not cleaning is necessary, cleaning is carried out, and the presence or absence of failing nozzles is inspected again. When cleaning is determined not to be necessary as a result of determining whether or not cleaning is necessary, the cleaning control ends without cleaning.

Description

  The present invention relates to a cleaning control method for a liquid discharge apparatus having a liquid discharge head in which a plurality of nozzles for discharging liquid droplets are arranged, and a liquid discharge apparatus.

  The ink jet printer includes a print head having a plurality of nozzles that eject ink droplets, and the print head is mounted on a carriage such that a nozzle forming surface on which the plurality of nozzles are arranged faces downward. Conventionally, as this type of ink jet printer, an ink jet printer having a head maintenance mechanism for performing maintenance of a print head exposed on the lower surface of a carriage is known (see, for example, Patent Document 1).

  In the ink jet printer described in Patent Document 1, the head maintenance mechanism includes a cleaning mechanism for cleaning the nozzles. The cleaning mechanism includes a wiping mechanism for wiping the nozzle forming surface, an ink suction mechanism for sucking ink from the nozzles, and the like. The head maintenance mechanism functions as an ink droplet ejection inspection device that inspects whether ink droplets are ejected from a plurality of nozzles (that is, inspects whether there are nozzles that are clogged). Also has. In the head maintenance mechanism, whether or not ink droplets are ejected from a plurality of nozzles is checked based on a change in current when the charged ink ejected from the nozzles lands on an absorbent material disposed in the head maintenance mechanism. Has been done.

JP 2009-190282 A

  In the ink jet printer described in Patent Document 1, an ink droplet ejection inspection is performed by an ink droplet ejection inspection device every time printing is performed on a predetermined number of printing sheets. Also, as a result of the ink droplet ejection inspection, when it is confirmed that a missing dot exists that includes a defective nozzle that does not eject ink, cleaning by a cleaning mechanism is performed to eliminate the missing dot.

  However, when the nozzle is clogged with foreign matter or the like, the failed nozzle does not recover even if cleaning is performed a plurality of times, and there is a high possibility that the missing dot will not be eliminated. In this way, when there is a high possibility that the missing dots will not be eliminated, if cleaning with ink consumption such as an ink suction operation is repeated, ink is wasted. Here, if the failed nozzle does not recover even after a plurality of cleanings, there is also a method of disabling the ink droplet ejection test so that the subsequent cleaning is not performed at the user's discretion. However, when the ink droplet ejection inspection is disabled, cleaning is not performed even if a dot dropout occurs thereafter, so that a failed nozzle that should be recovered cannot be recovered.

  Accordingly, an object of the present invention is to provide a liquid ejection device cleaning control method and a liquid ejection device capable of recovering a recoverable fault nozzle while suppressing wasteful consumption of droplets ejected from the nozzle. It is to propose.

  In order to solve the above-described problems, the present invention performs cleaning to eliminate the missing dot when a defective nozzle that does not eject droplets exists among a plurality of nozzles for ejecting droplets. A liquid ejection apparatus cleaning control method, comprising: a failed nozzle inspection step for inspecting presence / absence of the failed nozzle, an inspection result in the failed nozzle inspection step, and failed nozzle information which is information on the failed nozzle stored in advance And a cleaning necessity determination step for determining whether or not cleaning is necessary based on the above, and in the cleaning control, the cleaning necessity determination step determines that the cleaning is unnecessary In addition, the cleaning control is terminated without performing the cleaning.

  In the cleaning control method for a liquid ejection device of the present invention, in the cleaning necessity determination step for determining whether or not cleaning is necessary for eliminating dot omission, the inspection result in the failure nozzle inspection step for inspecting the presence or absence of a defective nozzle, Whether or not cleaning is necessary is determined based on failure nozzle information that is information on a failure nozzle stored in advance. Therefore, if a failure nozzle other than the failure nozzle that is assumed to be unrecoverable based on the failure nozzle information is not detected in the failure nozzle inspection step, if it is determined that cleaning is unnecessary in the cleaning necessity determination step, It is possible to avoid useless cleaning of a failed nozzle that cannot be recovered, and to suppress useless consumption of droplets ejected from the nozzle.

  In the present invention, in order to estimate whether or not the failed nozzle detected in the failed nozzle inspection step is a non-recoverable nozzle and determine whether or not cleaning is necessary, It is desirable to determine that the cleaning is unnecessary when the inspection result in the inspection step matches the previously stored failure nozzle information that is information on the failed nozzle.

  In the present invention, in the cleaning control, when it is determined in the cleaning necessity determination step that the cleaning is necessary, it is preferable to perform the cleaning and return to the failed nozzle inspection step. In this way, when a failed nozzle other than the failed nozzle that is assumed to be unrecoverable based on the failed nozzle information is detected in the failed nozzle inspection step, the cleaning is performed and it is impossible to recover. It becomes possible to recover a defective nozzle other than the estimated defective nozzle. Further, the recovery of the failed nozzles other than the failed nozzle that is assumed to be unrecoverable can be confirmed by the failed nozzle inspection step.

  In the present invention, the failed nozzle information is information on the number of failed nozzles, the number of failed nozzles detected in the failed nozzle inspection step is a first number of failed nozzles, and the failure based on the failed nozzle information Assuming that the number of nozzles is the number of second failed nozzles, the cleaning necessity determination step determines that the cleaning is unnecessary when the number of first failed nozzles and the number of second failed nozzles are the same. It is preferable to determine that the cleaning is necessary when the number of the first failed nozzles is different from the number of the second failed nozzles. That is, in the cleaning necessity determination step, a failure nozzle other than the failure nozzle that is estimated to be unrecoverable based on the failure nozzle information is failed by comparing the first failure nozzle number and the second failure nozzle number. It is preferable to estimate whether it was detected in the nozzle inspection step. With this configuration, the failed nozzle information is information for identifying the failed nozzle from the plurality of nozzles, and there is a failed nozzle other than the failed nozzle identified based on this failed nozzle information in the cleaning necessity determination step. Compared with the case where it is determined whether or not a fault nozzle other than the fault nozzle that is assumed to be unrecoverable based on the fault nozzle information is detected in the fault nozzle inspection step. Can be

  In the present invention, the cleaning control includes a cleaning number determining step of determining whether or not the cleaning has been performed a predetermined first number of times when it is determined in the cleaning necessity determining step that the cleaning is necessary. When the cleaning number determining step determines that the cleaning exceeding the first number has been performed, the failed nozzle information is stored with the first failed nozzle number as the new second failed nozzle number. A failure nozzle information storage step, and after the failure nozzle information storage step, the cleaning control is completed without performing the cleaning, and the failure nozzle information stored in the failure nozzle information storage step is the next cleaning. Used in the cleaning necessity determination step in the control Preferred. With such a configuration, the cleaning control does not perform cleaning more than the first number of times, so that it is possible to prevent unnecessary cleaning from being performed on a failed nozzle with low recoverability. In the next cleaning control, it is possible to appropriately determine whether or not cleaning is necessary based on the latest failed nozzle information.

  In the present invention, the cleaning control determines whether or not there is a history of occurrence of the failed nozzle when it is determined in the cleaning number determination step that the cleaning exceeding the first number has not been performed, and And a composite determination step for determining whether or not the cleaning has been performed exceeding a second number less than the first number, and the occurrence history of the failed nozzle remains in the composite determination step, and When it is determined that the cleaning exceeding the second number of times has been performed, the failed nozzle information storing step is executed, and the cleaning control is ended without performing the cleaning after the failed nozzle information storing step. . If the occurrence history of failed nozzles remains, there may be a case where the number of failed nozzles that cannot be recovered gradually increases. With this configuration, unnecessary cleaning is avoided and the nozzles are discharged from the nozzles. It is possible to suppress wasteful consumption of droplets. In addition, since unnecessary cleaning can be avoided, the throughput of the apparatus can be increased.

  In the present invention, the cleaning control includes a failed nozzle presence flag setting step for setting a failed nozzle presence flag when it is determined in the cleaning number determination step that the cleaning exceeding the first number has been performed. Is preferred. With this configuration, it is determined whether or not the failure nozzle occurrence history remains by determining whether or not the failure nozzle presence flag is set in the composite determination step during the next cleaning control. Can be determined.

  In the present invention, for example, when it is determined that the occurrence history of the failed nozzle remains and the cleaning exceeding the second number has been performed in the combined determination step, the failed nozzle information storage step and The failure nozzle presence flag setting step is executed, and the cleaning control is terminated without performing the cleaning after the failure nozzle information storing step and the failure nozzle presence flag setting step.

  In the present invention, the cleaning control includes a reset step for resetting the second failed nozzle number to 0 and resetting the failed nozzle presence flag when a failed nozzle is not detected in the failed nozzle inspection step. It is preferable. If no failed nozzle is detected in the failed nozzle inspection step, there is no unrecoverable failed nozzle. Therefore, with this configuration, the failed nozzle is detected in the failed nozzle inspection step during the next cleaning control. Sometimes, a predetermined number of cleanings can be performed to recover a recoverable fault nozzle.

  In the present invention, the failed nozzle information is nozzle identification information that identifies the failed nozzle from among the plurality of nozzles, and the failed nozzle identified based on the failed nozzle information in the cleaning necessity determination step. If the failed nozzle other than is detected in the failed nozzle inspection step, it is determined that the cleaning is necessary, and the failed nozzle other than the failed nozzle identified based on the failed nozzle information is the failed nozzle. If not detected in the inspection step, it may be determined that the cleaning is unnecessary. In this case, it is possible to determine the necessity of cleaning by excluding the non-recoverable failed nozzles identified based on the failed nozzle information. It is possible to accurately clean the failed nozzle that can be avoided and recovered. Therefore, it is possible to effectively recover a recoverable failed nozzle while effectively suppressing wasteful consumption of droplets ejected from the nozzle.

  In the present invention, the cleaning control includes a cleaning number determining step of determining whether or not the cleaning has been performed a predetermined first number of times when it is determined in the cleaning necessity determining step that the cleaning is necessary. And when the cleaning number determining step determines that the cleaning exceeding the first number has been performed, the failed nozzle information that stores the failed nozzle identified in the failed nozzle inspection step as the failed nozzle information. And the cleaning control is terminated without performing the cleaning after the failed nozzle information storing step, and the failed nozzle information stored in the failed nozzle information storing step is the cleaning in the next cleaning control. Used in the necessity determination step Door is preferable. With such a configuration, the cleaning control does not perform cleaning more than the first number of times, so that it is possible to prevent unnecessary cleaning from being performed on a failed nozzle with low recoverability. In the next cleaning control, it is possible to appropriately determine whether or not cleaning is necessary based on the latest failed nozzle information.

  In the present invention, the cleaning control excludes the failed nozzle that has ejected the droplet when the failed nozzle specified based on the failed nozzle information ejects a droplet in the failed nozzle inspection step. It is preferable to have a failed nozzle information update step for storing the nozzle identification information for identifying the failed nozzle as new failed nozzle information, and to execute the cleaning necessity determination step after the failed nozzle information update step. With this configuration, when a failed nozzle that has been estimated to be unrecoverable is recovered, it is possible to appropriately determine whether or not cleaning is necessary based on the updated failed nozzle information.

  In order to solve the above-described problem, the liquid ejection apparatus according to the present invention includes a liquid ejection head having a plurality of nozzles for ejecting droplets, and a malfunctioning nozzle that does not eject droplets into the plurality of nozzles. A droplet discharge inspection mechanism that inspects whether or not there is any missing dot, a cleaning mechanism that performs cleaning to eliminate the missing dot, and a storage unit that can store failed nozzle information that is information on the failed nozzle Cleaning mechanism control means for controlling whether or not the cleaning mechanism performs the cleaning according to the cleaning control method when a missing dot occurs in which a defective nozzle that does not discharge droplets exists among the plurality of nozzles. It is characterized by having.

  In the liquid ejection apparatus according to the present invention, the cleaning mechanism control unit performs cleaning based on the inspection result of the droplet ejection inspection mechanism that inspects the presence or absence of occurrence of missing dots and the failure nozzle information stored in the storage unit. The mechanism controls whether or not cleaning is performed. For this reason, the cleaning mechanism control means performs cleaning so that cleaning is not performed when a fault nozzle other than the fault nozzle that is assumed to be unrecoverable based on the fault nozzle information is not detected by the inspection by the droplet discharge inspection mechanism. By controlling the mechanism, useless cleaning can be avoided and useless consumption of droplets ejected from the nozzle can be suppressed. In addition, the cleaning mechanism control means performs cleaning so that cleaning is performed when a nozzle other than the nozzle that is estimated to be unrecoverable based on the nozzle information is detected by the droplet discharge inspection mechanism. If the mechanism is controlled, cleaning can be performed to recover a recoverable failed nozzle.

  In the present invention, the liquid ejection head is, for example, an inkjet head having a plurality of the nozzles for ejecting ink droplets. In this case, in a liquid ejection apparatus including an inkjet head, it is possible to recover a recoverable failed nozzle while suppressing wasteful consumption of ink droplets ejected from the nozzle.

  According to the present invention, in the cleaning necessity determination step for determining the necessity of cleaning for eliminating dot omission, the inspection result in the failure nozzle inspection step for inspecting the presence / absence of the failure nozzle and the previously stored failure nozzle Whether or not cleaning is necessary is determined on the basis of the failed nozzle information, which is information on the above. Therefore, if a failure nozzle other than the failure nozzle that is assumed to be unrecoverable based on the failure nozzle information is not detected in the failure nozzle inspection step, if it is determined that cleaning is unnecessary in the cleaning necessity determination step, It is possible to avoid useless cleaning of a failed nozzle that cannot be recovered, and to suppress useless consumption of droplets ejected from the nozzle.

1 is an external perspective view of an ink jet printer according to an embodiment of the present invention. 1 is a schematic perspective view showing a printer mechanism unit of an ink jet printer. The perspective view which takes out and shows a head maintenance unit. (A) is a figure which shows the relationship between the inkjet head and head cap at the time of flushing operation | movement, (B) is a figure which shows the relationship between the inkjet head and head cap at the time of ink suction operation | movement. The figure which shows the relationship between the inkjet head at the time of wiping operation | movement, and a head wiper. The figure which shows the relationship between the inkjet head and head cap at the time of an ink droplet discharge test. The schematic block diagram which shows a part of control part of an inkjet printer. 5 is a flowchart showing a flow of inkjet head cleaning control. 9 is a flowchart showing a flow of inkjet head cleaning control according to another embodiment.

  Hereinafter, an inkjet printer 1 and a control method thereof according to an embodiment of a liquid ejection apparatus of the present invention will be described in detail with reference to the drawings.

(Overall configuration of inkjet printer)
FIG. 1 is an external perspective view of an ink jet printer 1 according to an embodiment of the present invention. FIG. 2 is a schematic perspective view showing the printer mechanism unit 10 covered with the printer case 2 of the ink jet printer 1.

  The ink jet printer 1 performs color printing on a long recording paper fed from a roll paper using a plurality of types of color inks, and includes a printer case 2 having a rectangular parallelepiped shape as a whole. At the center of the front surface of the printer case 2, an opening 3 for mounting roll paper is formed. The opening 3 is sealed by an opening / closing lid 5 having a recording paper discharge guide 4 attached to the upper end. A recording paper discharge port 6 is formed between the recording paper discharge guide 4 and the upper edge portion of the opening 3 of the printer case 2. When the lock (not shown) is released and a finger is placed on the recording paper discharge guide 4 and pulled forward, the opening / closing lid 5 can be opened from the closed position shown in the drawing to the open position that falls forward about the lower end.

  A power switch 7a, a paper feed switch 7b, a plurality of operation state display lamps 7c, and the like are arranged on the right side of the opening / closing lid 5 on the front surface of the printer case 2. A mounting port 8 a of an ink cartridge mounting portion 8 having a vertically long rectangular cross section extending in the front-rear direction of the printer is opened on the left side portion of the opening / closing lid 5 on the front surface of the printer case 2, and the ink cartridge 9 is provided in the ink cartridge mounting portion 8. Is installed. When a button (not shown) is operated, the lock is released, the ink cartridge 9 is pushed forward by the spring force, and the ink cartridge 9 can be pulled out.

  As shown in FIG. 2, the printer mechanism unit 10 disposed inside the printer case 2 includes a printer main body frame 11 including a metal bottom plate 11a, left and right side plates 11b, 11c, and the like. A roll paper storage unit 12 is formed in the central portion of the printer main body frame 11 on the front side of the printer. When the opening / closing lid 5 is opened, the roll paper storage unit 12 opens forward, and the roll paper can be replaced.

  On the upper side of the roll paper storage unit 12, a platen 13 is stretched horizontally in the printer width direction. An inkjet head (liquid ejection head) 14 in which a plurality of nozzles (ink nozzles) for ejecting ink droplets (droplets) is formed is disposed on the upper side of the platen 13. The inkjet head 14 is mounted on the carriage 15 with a nozzle surface 14a (see FIG. 4) on which a plurality of ink nozzles are arranged facing downward.

  The carriage 15 can reciprocate in the printer width direction along a carriage guide shaft 15a that is horizontally stretched in the printer width direction. Specifically, the carriage 15 moves from a home position 15A indicated by a solid line in FIG. 2 that is deviated to the right side from the platen 13 to a left end position 15B that is delineated to the left side of the platen 13 in FIG. It is possible. The carriage 15 is connected to a drive mechanism including a motor, a transmission mechanism including a belt and a pulley, and the like.

  The carriage 15 is mounted with ink pumps for color ink, for example, ink pumps 16 a to 16 d for storing inks of four colors of cyan, magenta, yellow, and black. One end of each flexible ink tube 17a to 17d is connected to each ink pump 16a to 16d. The other ends of the flexible ink tubes 17a to 17d are connected to four ink supply paths (not shown) that extend in the vertical direction and are arranged at the rear end portion of the ink cartridge mounting portion 8. . Each of the ink supply paths communicates with the side of the ink cartridge 9 mounted on the ink cartridge mounting portion 8. The ink cartridge 9 stores ink bags storing cyan, magenta, yellow, and black inks, and the inks of the respective colors stored in these ink bags pass through the flexible ink tubes 17a to 17d. To the ink pumps 16a to 16d. Further, the ink supplied to the ink pumps 16a to 16d is supplied to the inkjet head 14 and discharged from the ink nozzles.

  A head maintenance unit 20 is incorporated in the right portion of the roll paper storage unit 12. When the carriage 15 is positioned at the home position 15A, the nozzle surface 14a of the inkjet head 14 mounted on the carriage 15 is in a state of facing the head maintenance unit 20 from above. Details of the head maintenance unit 20 will be described later.

  In a normal printing operation, the ink jet printer 1 causes the recording paper fed out from the roll paper stored in the roll paper storage unit 12 to move toward the recording paper discharge port 6 along the surface of the platen 13 by a transport mechanism (not shown). In synchronization with this conveyance, printing is performed on the recording paper while the inkjet head 14 is reciprocated left and right.

(Configuration of head maintenance unit)
FIG. 3 is a perspective view showing the head maintenance unit 20 taken out. FIG. 4A is a diagram illustrating the relationship between the inkjet head 14 and the head caps 22a and 22b during the flushing operation, and FIG. 4B is a diagram illustrating the inkjet head 14 and the head caps 22a and 22b during the ink suction operation. It is a figure which shows the relationship. FIG. 5 is a diagram showing the relationship between the inkjet head 14 and the head wiper 25 during the wiping operation. FIG. 6 is a diagram showing the relationship between the inkjet head 14 and the head caps 22a and 22b at the time of ink droplet ejection inspection.

  As shown in FIG. 3, the head maintenance unit 20 includes a unit case 21 having a rectangular parallelepiped shape that is elongated in the longitudinal direction of the printer as a whole. A head cap unit 22 including two head caps 22a and 22b is disposed at the upper end of the front portion of the unit case 21. The head caps 22a and 22b are disposed adjacent to each other in the carriage scanning direction. Further, the head caps 22a and 22b are opened above, and the opening faces the nozzle surface 14a of the inkjet head 14 disposed at the home position 15A. An ink absorber 23 is disposed inside the head caps 22a and 22b. As shown in FIG. 4, the inkjet printer 1 according to the present embodiment includes a pair of inkjet heads 14 </ b> A and 14 </ b> B arranged in parallel in the carriage scanning direction as the inkjet head 14.

  A head cap raising / lowering mechanism (not shown) for raising and lowering these components is incorporated under the head cap unit 22. Further, a tube pump (not shown) and a tube pump driving motor (not shown) are incorporated in a rear portion of the head cap lifting mechanism in the unit case 21.

  As shown in FIG. 4B, at the capping position 22A where the head caps 22a and 22b capping the nozzle surface 14a of the inkjet head 14 from below, an ink suction operation for sucking ink from each ink nozzle by a tube pump is performed. Is called. The waste ink sucked by the ink suction operation is sent out through the waste ink tube 24 by the tube pump. The waste ink tube 24 communicates with the ink cartridge 9 attached to the ink cartridge attachment portion 8, and the waste ink is collected in the waste ink storage portion in the ink cartridge 9. Further, as shown in FIG. 4A, at the flushing position 22B where the head caps 22a and 22b are retracted below the capping position 22A, a fixed amount of ink droplets are ejected from each ink nozzle toward the ink absorber 23. A flushing operation is performed.

  The head maintenance unit 20 is equipped with a wiping mechanism 26 that includes a head wiper 25 that wipes off extraneous ink and paper dust adhering to the nozzle surface 14 a of the inkjet head 14. The head wiper 25 is formed in a rectangular thin plate shape by a flexible material such as rubber, and is disposed on the rear side of the head cap unit 22 in the unit case 21. The front surface of the head wiper 25 is a wiping surface 25a that wipes ink from the nozzle surface 14a. On both the front and rear sides of the head wiper 25, liquid absorbers such as felt and sponge that absorb ink adhering to the head wiper 25 when ink is wiped from the nozzle surface 14a are disposed. The head wiper 25 is connected to a head wiper drive mechanism 27 that reciprocates the head wiper 25 in the front-rear direction.

  The head wiper drive mechanism 27 includes a rack formed to extend in the front-rear direction on the back surface of the long wiper case 28 that holds the head wiper 25, a pinion that meshes with the rack, and a rotational force from a drive source to the pinion. Is provided with a gear train or the like. In this embodiment, the drive source of the head wiper drive mechanism 27 is a tube pump drive motor.

  The head wiper 25 can reciprocate in the front-rear direction of the printer along the upper edge portion of the unit case 21 of the head maintenance unit 20. When the head wiper 25 moves from the rear side of the head cap unit 22 to the front side when the inkjet head 14 is at the home position 15A, as shown in FIG. 5, the pair of head wipers 25 are bent while being bent backward. A wiping operation is performed in which one nozzle surface 14a of the inkjet heads 14A and 14B is slid to wipe the nozzle surface 14a.

  Further, in the head maintenance unit 20 of the present embodiment, there are fault nozzles that do not eject ink droplets among the plurality of ink nozzles of the inkjet head 14 (that is, there are ink nozzles that are clogged). It also has a function of inspecting whether dot missing has occurred.

  As shown in FIG. 6, a metal bar 31 that is conductive to the ink absorber 23 is disposed inside the head caps 22 a and 22 b, and a lead wire 32 is connected to the lower end of the metal bar 31. ing. When charged ink droplets are ejected from the ink nozzles of the ink jet head 14 and the charged ink droplets land on the ink absorber 23, the current taken out via the metal rod 31 and the lead wire 32 changes. Further, it is possible to determine whether or not an ink droplet is ejected from each ink nozzle based on the change in current. In this way, the head maintenance unit 20 inspects whether or not dot missing has occurred (whether there is a failed nozzle) based on the change in current taken out through the metal rod 31 and the lead wire 32. Ink droplet ejection inspection is performed. In this embodiment, an ink droplet discharge inspection mechanism (droplet discharge inspection mechanism) 33 for inspecting the presence or absence of a failed nozzle is constituted by the ink absorber 23, the metal rod 31, the lead wire 32, and the like.

(Schematic configuration of control unit)
FIG. 7 is a schematic block diagram illustrating a part of the control unit 36 of the inkjet printer 1. The control unit 36 of the ink jet printer 1 includes a head maintenance unit control unit 37 for controlling the head maintenance unit 20. The head maintenance unit control unit 37 includes a memory 38 such as a ROM and a RAM, a CPU (not shown), and the like. An ink droplet discharge inspection mechanism 33 is connected to the head maintenance unit control unit 37, and the head maintenance unit control unit 37 detects dot missing based on a change in current taken out through the metal rod 31 and the lead wire 32. Is determined (that is, whether there is a failed nozzle). Further, the head maintenance unit control unit 37 identifies the number of failed nozzles.

  A cleaning mechanism 39 that performs cleaning for eliminating dot omission is connected to the control unit 36. The cleaning mechanism 39 includes a mechanism for performing a flushing operation of the ink pumps 16a to 16d, a mechanism for performing an ink suction operation such as a tube pump and a motor for driving the tube pump, and a wiping mechanism for performing a wiping operation. 26, and cleaning with consumption of ink is performed. A cleaning mechanism drive circuit 40 that drives a cleaning mechanism 39 is connected to the head maintenance unit controller 37.

(Inkjet head cleaning control)
FIG. 8 is a flowchart showing a flow of cleaning control of the inkjet head 14. In the ink jet printer 1, an ink droplet ejection test is performed at the home position 15 </ b> A during a pause after printing on a predetermined number of recording sheets. Also, as a result of the ink droplet ejection test, if there is a missing dot where there is a faulty nozzle (clogged ink nozzle), cleaning is performed under certain conditions to try to recover the faulty nozzle. . Hereinafter, the flow of cleaning control of the inkjet head 14 including the ink droplet ejection inspection will be described with reference to FIG.

  The cleaning control is performed for each pair of inkjet heads 14A and 14B. That is, an ink droplet ejection inspection is performed for each of the inkjet heads 14A and 14B, and it is determined whether or not dot missing has occurred. If dot missing has occurred, cleaning is performed for each of the inkjet heads 14A and 14B. Is done. Accordingly, even if dot missing occurs in the inkjet head 14A, if the dot missing does not occur in the inkjet head 14B, the inkjet head 14B is not cleaned, and even if dot missing occurs in the inkjet head 14B, the inkjet head. If there is no missing dot at 14A, the inkjet head 14A is not cleaned.

  When printing on a predetermined number of recording sheets is completed and the printer enters a resting state, the head maintenance unit control unit 37 resets the cleaning number counter in the memory 38 to “0” (step S1). Further, the control unit 36 discharges charged ink droplets from the ink nozzles of the inkjet head 14 at the home position 15A to perform an ink droplet discharge test (step S2), and the head maintenance unit control unit 37 performs dot missing. Whether or not has occurred is determined (step S3).

  If it is determined in step S3 that a missing dot has occurred, the head maintenance unit control unit 37 determines the result of the ink droplet ejection inspection in step S2 and the failure nozzle stored in the memory 38 in advance. Whether or not the inkjet head 14 needs to be cleaned is determined based on the failed nozzle information that is information (steps S4 to S6). In this embodiment, the failed nozzle information is information on the number of failed nozzles, and is stored in the memory 38 in step S13 described later or in step S8 described later during the previous cleaning control.

  In step S4, the head maintenance unit control unit 37 checks the number of failed nozzles (the number of first failed nozzles), which is the number of failed nozzles detected in the ink droplet ejection test, for the failed nozzles stored in the memory 38 in advance. It is determined whether the number is the same as the number of unrecoverable nozzles (second failed nozzle number). Here, when the number of inspection failure nozzles is the same as the number of non-recoverable nozzles, it is estimated that only non-recoverable failure nozzles exist (that is, there are no recoverable failure nozzles), and the number of inspection failure nozzles Is different from the number of non-recoverable nozzles, it can be estimated that there are recoverable failed nozzles.

  Therefore, if it is determined in step S4 that the number of inspection failure nozzles is the same as the number of unrecoverable nozzles, it is determined that cleaning is not necessary, and the inkjet head 14 is not cleaned, and the cleaning control ends. . On the other hand, if it is determined in step S4 that the number of inspection failure nozzles is different from the number of unrecoverable nozzles, the head maintenance unit control unit 37 determines whether or not the number of inspection failure nozzles is in an allowable range, that is, cleaning. Is determined (step S5). If it is determined that the number of inspection failure nozzles is acceptable and cleaning is not necessary (“No” in step S6), the inkjet head 14 is not cleaned and the cleaning control ends. If it is determined that the number of inspection failure nozzles is in an unacceptable range and cleaning is necessary (“Yes” in step S6), the head maintenance unit control unit 37 reads the cleaning number counter stored in the memory 38. It is determined whether or not exceeds a predetermined value (for example, 3) (step S7). That is, in step S7, the head maintenance unit control unit 37 determines whether or not a predetermined number of cleanings have been performed.

  If it is determined in step S7 that the cleaning number counter exceeds the predetermined value, the head maintenance unit control unit 37 stores the number of inspection failure nozzles detected in step S2 in the memory 38 as a new number of unrecoverable nozzles. (Step S8). That is, the head maintenance unit control unit 37 stores new failed nozzle information in the memory 38 with the number of inspection failed nozzles detected in step S2 as a new number of unrecoverable nozzles in step S8. This new failed nozzle information is used in step S4 in the next cleaning control.

  If it is determined in step S7 that the cleaning number counter exceeds the predetermined value, the head maintenance unit control unit 37 holds information indicating that there is a failed nozzle that cannot be recovered (failure nozzle occurrence history). Therefore, the failure nozzle presence flag is set in the memory 38 (step S9).

  In step S8, new failed nozzle information is stored in the memory 38, and when the failed nozzle presence flag is set in the memory 38 in step S9, the inkjet head 14 is not cleaned and the cleaning control ends.

  On the other hand, if it is determined in step S7 that the cleaning number counter does not exceed the predetermined value, the head maintenance unit control unit 37 determines whether or not the failure nozzle occurrence history remains in the memory 38 and It is determined whether or not the stored cleaning number counter exceeds a predetermined value (for example, 1) smaller than the predetermined value in step S7 (step S10). That is, in step S10, the head maintenance unit controller 37 determines whether or not the failure nozzle presence flag set in step S9 at the previous cleaning control is still set, and in step S7. It is determined whether or not cleaning has been performed less than a predetermined number of times.

  If it is determined in step S10 that the occurrence history of the failed nozzle remains in the memory 38 and the cleaning number counter exceeds the predetermined value, the process proceeds to steps S8 and S9, and the inkjet head 14 is not cleaned. Then, the cleaning control ends. If it is determined in step S10 that the occurrence history of the failed nozzle does not remain in the memory 38 and / or the cleaning number counter does not exceed the predetermined value, the head maintenance unit control unit 37 drives the cleaning mechanism. The circuit 40 is controlled, the cleaning mechanism 39 is driven, and the inkjet head 14 is cleaned (step S11). That is, cleaning with consumption of ink such as a flushing operation and an ink suction operation is performed. Thereafter, the head maintenance unit controller 37 adds “1” to the current cleaning number counter to update the cleaning number counter, stores the updated cleaning number counter in the memory 38 (step S12), and proceeds to step S2. Return.

  If it is determined in step S3 that no missing dot has occurred, the head maintenance unit control unit 37 resets the number of non-recoverable nozzles stored in the memory 38 to “0”, and the memory The fault nozzle presence flag 38 is reset (step S13). That is, in step S13, the head maintenance unit control unit 37 stores “0” in the memory 38 as a new number of unrecoverable nozzles and deletes the occurrence history of the failed nozzle stored in the memory 38. When the new number of unrecoverable nozzles is stored in the memory 38 and the failed nozzle presence flag in the memory 38 is reset, the process proceeds to step S4.

  In this embodiment, step S2 is a failed nozzle inspection step, steps S4 to S6 are cleaning necessity determination steps, step S7 is a cleaning number determination step, and step S8 is a failed nozzle information storage step. is there. Step S9 is a failure nozzle presence flag setting step, step S10 is a composite determination step, and step S13 is a reset step. In the present embodiment, the memory 38 is a storage unit capable of storing failed nozzle information, and the head maintenance unit control unit 37 includes the inspection result in the ink droplet ejection inspection mechanism 33 and the failure stored in the storage unit. The cleaning mechanism control means controls whether or not the cleaning mechanism 39 performs cleaning based on the nozzle information.

(Main effects of this embodiment)
As described above, in this embodiment, if the number of inspection failure nozzles is the same as the number of non-recoverable nozzles, it is estimated that there is only a non-recoverable failure nozzle, and it is determined that cleaning is unnecessary. In this case, the cleaning control is terminated without cleaning the inkjet head 14. Therefore, it is possible to avoid useless cleaning of a failed nozzle that cannot be recovered, and to suppress useless consumption of ink droplets ejected from the ink nozzle. In this embodiment, if the number of inspection failure nozzles is different from the number of unrecoverable nozzles, it is estimated that there is a recoverable failure nozzle. If a predetermined condition is satisfied, it is determined that cleaning is necessary. If it is determined that cleaning is necessary, the inkjet head 14 is cleaned if a predetermined condition is satisfied. Therefore, it is possible to recover the failed nozzle that can be recovered by cleaning the recoverable failed nozzle.

  In this embodiment, the failed nozzle information is information on the number of failed nozzles. In step S4, by comparing the number of inspection failed nozzles with the number of unrecoverable nozzles, it is impossible to recover based on the failed nozzle information. It is estimated whether or not a failed nozzle other than the estimated failed nozzle is detected in step S2. Therefore, the failed nozzle information is information for identifying a failed nozzle from a plurality of nozzles, and whether or not there is a failed nozzle other than the unrecoverable failed nozzle specified based on this information. The control can be simplified compared with the case where it is determined whether or not a failed nozzle other than the failed nozzle that is assumed to be unrecoverable based on the failed nozzle information is detected in step S2.

  In this embodiment, if it is determined in step S7 that the cleaning number counter exceeds a predetermined value, the inkjet head 14 is not cleaned and the cleaning control is terminated. Further, in the case where the occurrence history of failed nozzles remains, there may be a case where the number of failed nozzles that cannot be recovered gradually increases. However, in this embodiment, the cleaning number counter exceeds a predetermined value in step S7. If it is determined that there is not, the occurrence history of the failed nozzle remains in the memory 38 in step S10, and if it is determined that the cleaning counter exceeds a predetermined value smaller than the predetermined value in step S7. The cleaning control is terminated without cleaning the inkjet head 14. For this reason, it is possible to prevent unnecessary nozzles from being cleaned more than necessary with respect to a faulty nozzle having a low recovery possibility, thereby suppressing wasteful consumption of ink droplets ejected from the ink nozzles. In addition, the throughput of the apparatus can be increased.

  In this embodiment, in step S8, the number of inspection failure nozzles detected in step S2 is stored in the memory 38 as a new number of unrecoverable nozzles, and this new number of unrecoverable nozzles is used in the next cleaning control. . Therefore, in the next cleaning control, it becomes possible to appropriately determine the necessity of cleaning based on the latest number of unrecoverable nozzles. In this embodiment, since the failed nozzle presence flag is set in step S9, it is determined whether or not the failed nozzle presence flag is set in the memory 38 in step S10 during the next cleaning control. It is possible to determine whether or not the occurrence history of the failed nozzle remains.

  In this embodiment, if no failed nozzle is detected in step S2, “0” is stored in the memory 38 as a new number of unrecoverable nozzles, and the occurrence history of the failed nozzle stored in the memory 38 is deleted. Therefore, if a failed nozzle is detected in step S2 during the next cleaning control, it is possible to perform a predetermined number of cleanings and recover a recoverable failed nozzle.

(Modified example of inkjet head cleaning control)
FIG. 9 is a flowchart showing a flow of cleaning control of the inkjet head 14 according to the modification. In the embodiment described above, the failed nozzle information is information on the number of failed nozzles, but the failed nozzle information may be nozzle specifying information for specifying a failed nozzle from among a plurality of ink nozzles. In this case, for example, the cleaning control is executed according to the flow shown in FIG.

  That is, when printing on a predetermined number of recording sheets is completed and the printer enters a resting state, the head maintenance unit control unit 37 resets the cleaning number counter in the memory 38 to “0” (step S21), and the control unit 36. Performs an ink droplet ejection test (step S22). In step S22, the head maintenance unit control unit 37 identifies a failed nozzle from among the plurality of ink nozzles.

  Thereafter, the head maintenance unit control unit 37 determines whether or not the inkjet head 14 needs to be cleaned based on the ink droplet ejection test in step S22 and the failed nozzle information stored in the memory 38 in advance (step S23). To S25). In the present embodiment, the failed nozzle information is nozzle identification information as described above, and is stored in the memory 38 in step S30 described later or in step S27 described later during the previous cleaning control.

  In step S <b> 23, the head maintenance unit control unit 37 determines whether or not the non-recoverable nozzle, which is a failed nozzle stored in advance in the memory 38, has normally ejected. If it is determined in step S23 that the non-recoverable nozzles are not normally ejected, in step S24, the head maintenance unit control unit 37 obtains the inspection result regarding the non-recoverable nozzles from the ink droplet discharge inspection results in step S22. Except for the necessity of cleaning. That is, in step S24, the head maintenance unit control unit 37 can tolerate whether or not a failed nozzle other than the non-recoverable nozzle has been detected in the ink droplet ejection test, and the number of detected failed nozzles other than the non-recoverable nozzle. It is determined whether or not it is within the range (that is, whether or not cleaning is necessary).

  If it is determined in step S24 that a faulty nozzle other than the non-recoverable nozzle has not been detected in the ink droplet ejection test, the head maintenance unit control unit 37 estimates that only a faulty nozzle that cannot be recovered exists, and performs cleaning. Is determined to be unnecessary (“No” in step S25). Alternatively, in step S24, when a failed nozzle other than the non-recoverable nozzle is detected by the ink droplet ejection test, if it is determined that the number of failed nozzles is within an allowable range, the head maintenance unit control unit 37 It is determined that cleaning is not required (“No” in step S25). If it is determined in step S25 that cleaning is not necessary, the inkjet head 14 is not cleaned, and the cleaning control ends.

  On the other hand, if it is determined in step S24 that a failed nozzle other than the unrecoverable nozzle is detected by the ink droplet ejection test, the head maintenance unit control unit 37 estimates that a recoverable failed nozzle exists, If it is determined that the number of failed nozzles other than the non-recoverable nozzles detected is not within an allowable range, the head maintenance unit control unit 37 determines that cleaning is necessary (“Yes” in step S25). If it is determined in step S25 that cleaning is necessary, the head maintenance unit control unit 37 determines whether or not the cleaning number counter stored in the memory 38 exceeds a predetermined value (for example, 3) (step S25). Step S26).

  If it is determined in step S26 that the cleaning number counter exceeds the predetermined value, the head maintenance unit control unit 37 stores the failed nozzle specified in step S2 in the memory 38 as a new unrecoverable nozzle (step S26). S27). That is, in step S27, the head maintenance unit control unit 37 stores, in the memory 38, new failed nozzle information that sets the failed nozzle identified in step S2 as a new unrecoverable nozzle. This new failed nozzle information is used in steps S23 and S24 in the next cleaning control. When new failed nozzle information is stored in the memory 38 in step S27, the cleaning of the inkjet head 14 is not performed and the cleaning control ends.

  If it is determined in step S26 that the cleaning number counter does not exceed the predetermined value, the head maintenance unit control unit 37 controls the cleaning mechanism drive circuit 40 to drive the cleaning mechanism 39, and the inkjet head 14 Cleaning is performed (step S28). That is, a flushing operation, an ink suction operation, and the like are performed. Thereafter, the head maintenance unit control unit 37 adds “1” to the current cleaning number counter to update the cleaning number counter, stores the updated cleaning number counter in the memory 38 (step S29), and proceeds to step S22. Return.

  If it is determined in step S23 that there is an unrecoverable nozzle that has been normally ejected, the head maintenance unit control unit 37 stores the unrecoverable nozzles other than the unrecoverable nozzle that has been normally ejected in the memory 38 as new unrecoverable nozzles. (Step S30). In other words, in step S30, the head maintenance unit control unit 37 stores, in the memory 38, nozzle specifying information for specifying non-recoverable nozzles excluding normally recoverable non-recoverable nozzles as new failed nozzle information. When new failed nozzle information is stored in step S30, the process proceeds to step S24.

  In the flowchart shown in FIG. 9, step S22 is a failed nozzle inspection step, steps S23 to S25 are cleaning necessity determination steps, step S26 is a cleaning number determination step, and step S27 is failed nozzle information. This is a storage step, and step S30 is a failed nozzle information update step.

  In the cleaning control according to the modification, the failed nozzle information is nozzle identification information that identifies a failed nozzle from among a plurality of ink nozzles. Also, if no faulty nozzles other than non-recoverable nozzles have been detected in the ink droplet ejection test, it is assumed that there are only non-recoverable faulty nozzles, and it is determined that cleaning is not necessary. When the nozzle is detected by the ink droplet ejection test, the head maintenance unit control unit 37 estimates that there is a recoverable failed nozzle, and determines that the cleaning is necessary if a predetermined condition is satisfied. Therefore, in this case, as compared with the above-described embodiment, it is possible to accurately avoid useless cleaning for non-recoverable nozzles and to accurately perform cleaning for recoverable failed nozzles. Therefore, it is possible to effectively recover a recoverable failed nozzle while effectively suppressing wasteful consumption of droplets ejected from the nozzle.

  Further, in the cleaning control according to the modified example, when it is determined in step S23 that there is a non-recoverable nozzle that has been normally ejected, non-recoverable nozzles that are normally ejected are stored in the memory 38 as new unrecoverable nozzles. To do. Therefore, when a failed nozzle estimated to be unrecoverable is recovered, the necessity of cleaning can be appropriately determined based on the updated failed nozzle information.

(Other embodiments)
In the embodiment described above, the fault nozzle presence flag is set in the memory 38 in step S9, but step S9 may be omitted. In this case, step S10 is also omitted.

  In the above-described embodiment, the embodiment of the liquid discharge apparatus according to the present invention has been described by taking the inkjet printer 1 as an example. However, the liquid discharge apparatus to which the configuration of the present invention is applied includes a liquid crystal display, an organic EL display, and an FED (surface emitting device). A liquid discharge device including a liquid discharge head for discharging liquid such as an electrode material or a color material used for electrode formation of a display) from a nozzle, and a liquid discharge head for discharging a bio-organic matter used for biochip manufacture from the nozzle. A liquid discharge apparatus or a liquid discharge apparatus including a liquid discharge head that discharges a sample from a nozzle as a precision pipette may be used.

  DESCRIPTION OF SYMBOLS 1 Inkjet printer (liquid ejection apparatus), 14 Inkjet head (droplet ejection head), 33 Ink droplet ejection inspection mechanism (droplet ejection inspection mechanism), 37 Head maintenance unit control part (cleaning mechanism control means), 38 Memory (memory) Means), 39 cleaning mechanism, S2 / S22 failed nozzle inspection step, S4-S6 / S23-S25 cleaning necessity determination step, S7 / S26 cleaning frequency determination step, S8 / S27 failed nozzle information storage step, S9 failed nozzle presence flag Set step, S10 Composite determination step, S13 Reset step, S30 Fault nozzle information update step

Claims (14)

A cleaning control method for a liquid ejection apparatus that performs cleaning to eliminate the missing dot when a missing dot exists in which a defective nozzle that does not eject a droplet exists among a plurality of droplet ejection nozzles,
A failed nozzle inspection step for inspecting the presence or absence of the failed nozzle;
Performing cleaning control including a cleaning necessity determination step for determining whether or not the cleaning is necessary based on an inspection result in the failure nozzle inspection step and failure nozzle information which is information on the failure nozzle stored in advance. And
In the cleaning control, a cleaning control method for a liquid ejection apparatus, wherein the cleaning control is terminated without performing the cleaning when the cleaning is determined to be unnecessary in the cleaning necessity determination step.   In the cleaning necessity determination step, it is determined that the cleaning is unnecessary when the inspection result in the defective nozzle inspection step matches the preliminarily stored failure nozzle information that is information on the failed nozzle. The cleaning control method for a liquid ejection apparatus according to claim 1, wherein:   3. The liquid according to claim 2, wherein in the cleaning control, when it is determined in the cleaning necessity determination step that the cleaning is necessary, the cleaning is performed and the process returns to the failed nozzle inspection step. A cleaning control method for a discharge device. The failed nozzle information is information on the number of failed nozzles,
When the number of the failed nozzles detected in the failed nozzle inspection step is the first failed nozzle number, and the number of the failed nozzles based on the failed nozzle information is the second failed nozzle number,
In the cleaning necessity determination step, when the first number of failed nozzles and the second number of failed nozzles are the same, it is determined that the cleaning is unnecessary, and the first number of failed nozzles and the second number of failed nozzles are determined. 4. The cleaning control method for a liquid ejection apparatus according to claim 3, wherein the cleaning is determined to be necessary when the number of nozzles is different. The cleaning control includes a cleaning number determining step of determining whether or not the cleaning has been performed a predetermined first number of times when the cleaning is determined to be necessary in the cleaning necessity determining step; In the number determination step, when it is determined that the cleaning exceeding the first number has been performed, the failed nozzle information for storing the failed nozzle information with the first number of failed nozzles as the new number of second failed nozzles A memory step;
The cleaning control ends without performing the cleaning after the failed nozzle information storing step,
5. The cleaning control method for a liquid ejection apparatus according to claim 4, wherein the failed nozzle information stored in the failed nozzle information storing step is used in the cleaning necessity determination step in the next cleaning control. In the cleaning control, in the step of determining the number of cleaning times, if it is determined that the cleaning exceeding the first number of times has not been performed, whether or not the occurrence history of the failed nozzle remains, and the first A composite determination step of determining whether or not the cleaning has been performed exceeding a second number less than the number of times,
In the combined determination step, when it is determined that the occurrence history of the failed nozzle remains and the cleaning exceeding the second number has been performed, the failed nozzle information storage step is executed, and the failed nozzle 6. The cleaning control method for a liquid ejection apparatus according to claim 5, wherein the cleaning control is terminated without performing the cleaning after the information storing step. The cleaning control includes a failure nozzle presence flag setting step for setting a failure nozzle presence flag when it is determined in the cleaning frequency determination step that the cleaning exceeding the first number has been performed.
In the next cleaning control, in the composite determination step, it is determined whether or not the failure nozzle occurrence history remains by determining whether or not the failure nozzle presence flag is set. A cleaning control method for a liquid ejection apparatus according to claim 6.   In the combined determination step, when it is determined that the occurrence history of the failed nozzle remains and the cleaning exceeding the second number has been performed, the failed nozzle information storing step and the failed nozzle presence flag set 8. The cleaning control method for a liquid ejecting apparatus according to claim 7, wherein a step is executed, and the cleaning control is terminated without performing the cleaning after the failed nozzle information storing step and the failed nozzle presence flag setting step. .   The cleaning control includes a reset step of resetting the second failed nozzle number to 0 and resetting the failed nozzle presence flag when a failed nozzle is not detected in the failed nozzle inspection step. 9. The cleaning control method for a liquid ejection apparatus according to claim 7, wherein the cleaning control method is used. The failed nozzle information is nozzle identification information for identifying the failed nozzle from a plurality of the nozzles,
In the cleaning necessity determination step, if the failed nozzle other than the failed nozzle specified based on the failed nozzle information is detected in the failed nozzle inspection step, it is determined that the cleaning is necessary, 4. The cleaning according to claim 3, wherein the cleaning is determined to be unnecessary if the failed nozzles other than the failed nozzle identified based on the failed nozzle information are not detected in the failed nozzle inspection step. Cleaning control method for liquid ejection device. The cleaning control includes a cleaning number determining step of determining whether or not the cleaning has been performed a predetermined first number of times when the cleaning is determined to be necessary in the cleaning necessity determining step; A failure nozzle information storage step of storing the failed nozzle specified in the failed nozzle inspection step as the failed nozzle information when it is determined in the number of times determination step that the cleaning exceeding the first number of times has been performed. Have
The cleaning control ends without performing the cleaning after the failed nozzle information storing step,
11. The cleaning control method for a liquid ejection apparatus according to claim 10, wherein the failed nozzle information stored in the failed nozzle information storage step is used in the cleaning necessity determination step in the next cleaning control. In the cleaning nozzle inspection step, when the failed nozzle specified based on the failed nozzle information ejects a droplet in the failed nozzle inspection step, the failed nozzle except for the failed nozzle that ejected the droplet is removed. A fault nozzle information update step for storing the nozzle specification information to be specified as new fault nozzle information;
12. The cleaning control method for a liquid ejection apparatus according to claim 11, wherein the cleaning necessity determination step is executed after the failed nozzle information update step. A liquid discharge head having a plurality of nozzles for discharging liquid droplets;
A droplet discharge inspection mechanism for inspecting the presence or absence of occurrence of missing dots in which a defective nozzle that does not discharge droplets exists among the plurality of nozzles;
A cleaning mechanism for cleaning to eliminate the missing dots,
Storage means capable of storing failed nozzle information which is information of the failed nozzle;
13. When a dot missing occurs in which a defective nozzle that does not discharge droplets exists among the plurality of nozzles, the cleaning mechanism performs the cleaning by the cleaning control method according to any one of claims 1 to 12. And a cleaning mechanism control means for controlling whether or not the liquid is discharged.   The liquid ejecting apparatus according to claim 13, wherein the liquid ejecting head is an ink jet head having a plurality of the nozzles for ejecting ink droplets.

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