JP2018012339A - Liquid discharge device and control method for the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a liquid discharge device capable of suppressing an increase in loss time when a discharge head cannot discharge liquid onto a medium in association with execution of maintenance of the discharge head for discharging the liquid.SOLUTION: A control unit of a printer (liquid discharge device) determines whether or not discharge of ink from a defective nozzle can be complemented by discharge of the ink from a normal nozzle for each defective nozzle (S52). Further, the control unit permits the discharge of the ink on the basis of a discharge command while complementing all the defective nozzles (S55) when all defective nozzles can be complemented (S54:YES), and executes maintenance with strength such that the larger the number of defective nozzles is, the higher the strength is (S61 and S62) when all the defective nozzles cannot be complemented (S54:NO).SELECTED DRAWING: Figure 14

Description

  The present invention relates to a liquid ejection apparatus such as an ink jet printer.

  2. Description of the Related Art Conventionally, as an example of a liquid ejecting apparatus, an ink jet printing apparatus that forms characters and images by ejecting ink as an example of a liquid onto a medium such as paper is known. In such a printing apparatus, a recording head having a plurality of nozzles, a detection unit that detects a defective nozzle that is unable to eject ink normally, a determination unit that determines the level of occurrence of a defective nozzle, and a determination unit And a control unit for controlling the operation of the printing apparatus based on the determination result (for example, Patent Document 1). In this printing apparatus, the execution frequency of the cleaning operation can be changed based on the cleaning level set by the user.

JP 2006-142807 A

  However, in the printing apparatus as described above, depending on the setting of the cleaning level, there is a possibility that a loss time (down time) at which printing cannot be performed increases due to frequent cleaning operations. Such a situation is not limited to the ink jet printing apparatus, but is generally common to liquid ejecting apparatuses that can perform maintenance of an ejection head that ejects liquid.

  The present invention has been made in view of the above circumstances. It is an object of the present invention to provide a liquid ejection apparatus that can suppress an increase in loss time during which the ejection head cannot eject liquid onto a medium as a result of performing maintenance of the ejection head that ejects liquid.

Hereinafter, means for solving the above-described problems and the effects thereof will be described.
A liquid discharge apparatus that solves the above-described problems is based on a discharge head having a plurality of nozzles that can discharge liquid toward a medium, a maintenance unit that performs maintenance of the discharge head, and a discharge command of the liquid. A control unit that discharges the liquid to the medium, and a discharge failure detection unit that detects a discharge failure of the nozzle. The nozzle in which the discharge failure is detected is defined as a defective nozzle, and the discharge failure is detected. In a case where the nozzle that has not been detected is a normal nozzle, the control unit can complement the discharge of the liquid from the defective nozzle by the discharge of the liquid from the normal nozzle when the defective nozzle is detected. For each of the defective nozzles, and if the complement is possible for all of the defective nozzles, the liquid based on the discharge command is provided after the complementation. Allow the discharge, if not possible the complement of all of the defective nozzle to perform the maintenance with high strength as the number of the defective nozzle is large.

  According to the above configuration, even when there are one or more defective nozzles, when the defective nozzles can be complemented, liquid ejection based on the ejection command is permitted. Therefore, in this case, even when there is a defective nozzle, it is possible to discharge the liquid toward the medium after supplementing the defective nozzle without performing maintenance. On the other hand, when there are one or more defective nozzles and the defective nozzles cannot be complemented, maintenance with higher strength is executed as the number of defective nozzles increases. For this reason, it is possible to perform maintenance with appropriate strength according to the number of defective nozzles. Thus, according to this configuration, it is possible to suppress an increase in the loss time during which liquid cannot be discharged with the execution of maintenance.

  In the liquid ejecting apparatus, when the complement is not possible for all the defective nozzles, the control unit performs the maintenance until the complement is possible for all the defective nozzles, and then performs the maintenance. It is desirable to permit the discharge of the liquid based on the discharge command after performing the above-described supplement for the defective nozzle.

  According to the above configuration, maintenance is performed until the defective nozzle can be complemented. For this reason, it is possible to suppress a drop in the landing accuracy of the liquid on the medium due to the occurrence of the defective nozzle.

  In the liquid ejecting apparatus, it is preferable that the control unit permits the ejection of the liquid based on the ejection command when the number of executions of the maintenance reaches a predetermined number of times set in advance.

  According to the above-described configuration, it is possible to prevent the discharge of the liquid based on the discharge command from being started by performing maintenance indefinitely because there is a defective nozzle that cannot be complemented.

In the liquid ejecting apparatus, it is preferable that the control unit notifies the fact when the number of maintenance executions reaches the specified number.
According to the above configuration, it is possible for the user of the liquid ejection apparatus to recognize that all defective nozzles cannot be complemented even if the prescribed number of maintenances are performed.

  In the liquid ejecting apparatus, when the number of executions of the maintenance reaches the specified number of times, the control unit supplements the defective nozzles that can be complemented among the defective nozzles, and then performs the ejection. It is desirable to permit discharge of liquid based on the command.

  According to the above configuration, even when there are defective nozzles that cannot be complemented even after the prescribed number of maintenances are performed, the defective nozzles that can be complemented are complemented and liquid ejection is permitted. For this reason, even when there is a defective nozzle, it is possible to suppress a drop in the landing accuracy of the liquid on the medium.

  In the liquid ejecting apparatus, the control unit, when there is the ejection command for ejecting liquid to a plurality of the media, whenever the ejection of the liquid to one or more of the media is completed, When an ejection failure detection unit detects an ejection failure between the media to detect ejection failure of the nozzle, and the failure nozzle is detected in the ejection failure between the media, the complement among the defective nozzles is possible It is desirable to supplement the defective nozzle.

  According to the above configuration, when liquid is ejected to a plurality of media, the ejection failure between the media is detected after the liquid ejection to a certain medium is finished and before the liquid ejection to the next medium is started. Is executed. If there is a defective nozzle as a result of the ejection failure detection between the media, the defective nozzle is complemented as much as possible, and then liquid ejection to the next medium is started. Therefore, according to this configuration, when liquid is ejected to a plurality of media based on a liquid ejection command, it is possible to suppress a decrease in the accuracy of landing of the liquid on the medium as compared with a case where no complement is performed. it can.

  In the liquid ejection apparatus, the ejection head includes a plurality of nozzle groups including a plurality of the nozzles, and the control unit is configured to detect a part of the plurality of nozzle groups in the single ejection failure between the media. It is desirable that the nozzle group is a detection target of liquid discharge failure, and that a part of the nozzle group that is a detection target of liquid discharge failure is changed every time the inter-medium discharge failure detection is executed.

  According to the above configuration, since all nozzle groups are not subject to inspection in one ejection failure between mediums, the time required for one ejection failure detection between media can be shortened. On the other hand, since the nozzle group to be inspected is changed every time the ejection failure between the media is detected, it is possible to suppress the generation of the nozzle group in which the ejection failure is not detected over a long period of time.

1 is a perspective view of a multifunction machine according to an embodiment. 1 is a schematic diagram illustrating a schematic configuration of a printing apparatus. The bottom view which shows the arrangement | sequence of the discharge head of the said printing apparatus. FIG. 3 is a cross-sectional view of a pressure adjusting mechanism and a discharge head of the printing apparatus. Sectional drawing of the pressure adjustment mechanism and nozzle at the time of execution of pressurization cleaning. FIG. 2 is a block diagram showing an electrical configuration of the printing apparatus. The schematic diagram which shows the medium on which the nozzle check pattern was printed. The schematic diagram explaining neighborhood complement. The schematic diagram explaining alternative complement and color mixture complement. The flowchart which shows the process routine which a control part performs at the time of initial filling. 6 is a flowchart illustrating a processing routine executed by a control unit when printing based on a print job is started. 6 is a flowchart illustrating a processing routine executed by a control unit during printing based on a print job. 6 is a flowchart illustrating a processing routine executed by the control unit when printing based on a print job is completed. The flowchart which shows the process routine which a control part performs in order to perform automatic maintenance. The flowchart which shows the process routine which a control part performs in order to determine a discharge defect level. The flowchart which shows the process routine which a control part performs in order to perform manual maintenance. 6 is a flowchart illustrating a processing routine that is executed by the control unit when returning from the emergency stop when the operation of the printing apparatus is emergency stopped. The flowchart which shows the process routine which a control part performs in order to perform automatic maintenance. 6 is a flowchart illustrating a processing routine executed by a control unit when printing based on a print job is started.

  Hereinafter, an embodiment in which a liquid ejecting apparatus is embodied in a printing apparatus will be described with reference to the drawings. In the present embodiment, the printing apparatus is an ink jet printer that forms characters and images by ejecting ink as an example of a liquid onto a medium such as paper.

  As illustrated in FIG. 1, the multifunction device 10 includes a printing device 11 that performs printing on the medium S, an image reading device 12 that reads an image printed on the medium S, and a display that displays various types of information on the multifunction device 10. Unit 13. The printing apparatus 11 includes a feeding cassette 14 that stores a medium S before printing, and a first discharge tray 15 from which the printed medium S is discharged. The image reading device 12 includes a feeding tray 16 that supports the medium S on which an image to be read is printed, and a second discharge tray 17 from which the read medium S is discharged.

  The display unit 13 preferably has an operation function in addition to a display function, such as a touch display. When the display unit 13 does not have an operation function, it is desirable that the multifunction machine 10 is provided with a physical key around the display unit 13. The multifunction machine 10 according to the present embodiment has a FAX function in addition to a printing function and an image reading function.

Next, the printing apparatus 11 will be described in detail with reference to FIGS.
As shown in FIG. 2, the printing apparatus 11 includes a discharge head 22 in which a plurality of nozzles 21 capable of discharging ink are opened, and a supply mechanism for pressure-supplying ink from a liquid supply source 23 toward the discharge head 22. 24 and a pressure adjusting mechanism 25 that adjusts the pressure of the ink supplied to the ejection head 22. In addition, the printing apparatus 11 includes a maintenance device 26 that maintains the ejection head 22 and a control unit 100 that controls various components of the printing apparatus 11.

  Further, the printing apparatus 11 includes a line head 31 including a plurality of ejection heads 22 arranged in parallel so that the printing range extends over the entire width of the medium S as a component. The line head 31 has a liquid supply path 32 for supplying ink to the ejection head 22. A pressure adjustment mechanism 25 is provided in the middle of the liquid supply path 32.

  The liquid supply source 23 is a liquid storage bag stored in the storage container 33, for example. The liquid supply source 23 is formed of a flexible bag and contains ink therein. A plurality of liquid supply sources 23 and storage containers 33 are provided for each type of ink (ink color in the present embodiment). The supply mechanism 24 includes a liquid lead-out path 34 that communicates with the liquid supply source 23, a gas delivery path 35 that communicates with the internal space of the storage container 33, and a pressurizing valve 36 (switching valve) provided in the gas delivery path 35. And a pressurizing pump 37 that sends gas (for example, air) into the internal space of the receiving container 33 through the gas delivery path 35.

  When the gas is sent through the gas delivery path 35 by driving the pressurizing pump 37, the gas enters the container 33 and the pressure in the container 33 increases. Then, the bag constituting the liquid supply source 23 is compressed, and the ink stored inside flows out into the liquid outlet path 34 in a pressurized state. The pressurizing pump 37 is driven at any time as the pressure of the liquid outlet path 34 decreases so that the ink in the liquid outlet path 34 is maintained at a predetermined positive pressure.

  The liquid lead-out path 34 is branched into a plurality, and is connected to a liquid supply path 32 provided in the line head 31 so that the branched downstream end corresponds to each discharge head 22. The liquid supply path 32 and the pressure adjustment mechanism 25 are provided for each type of ink in each ejection head 22.

  Specifically, when the inks stored in the four liquid supply sources 23 are respectively supplied to the four ejection heads 22, one ejection head 22 is provided with four pressure adjustment mechanisms 25 for each type of ink. Note that a filter for filtering foreign matter in the ink may be provided upstream of the pressure adjustment mechanism 25 in the liquid supply path 32.

  The ejection head 22 has a common liquid chamber 41 for temporarily storing ink supplied through a liquid supply path 32 provided for each type of ink, and a plurality of cavities provided to individually correspond to the plurality of nozzles 21. 42 and a plurality of actuators 43 provided so as to correspond to the respective cavities 42.

  As shown in FIG. 3, in the present embodiment, the ejection head 22 has a plurality of nozzle rows 27 each composed of a plurality of nozzles 21 that eject ink, for each type of ink (every four types in the present embodiment). That is, the nozzle row 27 is a set of nozzles 21 to which ink is supplied from one common liquid chamber 41, and corresponds to an example of a “nozzle group” in the present embodiment.

  Specifically, a nozzle row 27c including a plurality of nozzles 21c that discharge cyan ink and a nozzle row 27m including a plurality of nozzles 21m that discharge magenta ink are formed on the nozzle forming surface 28 of the discharge head 22. . The nozzle forming surface 28 is formed with a nozzle row 27y composed of a plurality of nozzles 21y that ejects yellow ink and a nozzle row 27k composed of a plurality of nozzles 21k that eject black ink.

  In the following description, with respect to the nozzles 21 constituting the nozzle row 27, the nozzle 21 closest to the first end (left side in FIG. 3) in the width direction X is defined as the first nozzle 21 (1). The nozzle 21 on the second end side (right side in FIG. 3) is defined as the nth nozzle 21 (n). In addition, the i-th nozzle 21 counted from the first end side is referred to as an i-th nozzle 21 (i).

  Further, on the nozzle formation surface 28 of the ejection head 22, a plurality of nozzle rows 27 that eject different types of ink are generated so as to be aligned in the transport direction F of the medium S that intersects the width direction X. In the ejection head 22, an i-th nozzle 21c (i) that ejects cyan ink, an i-th nozzle 21m (i) that ejects magenta ink, an i-th nozzle 21y (i) that ejects yellow ink, The i-th nozzle 21k (i) that discharges black ink is formed so as to overlap when projected in the transport direction F.

  As described above, the line head 31 includes the first ejection head 221, the second ejection head 222, the third ejection head 223, and the fourth ejection head 224 as the plurality of ejection heads 22. These discharge heads 22 are alternately arranged in the width direction X and the conveyance direction F in the line head 31 and are arranged so as to partially overlap in the width direction X. Thus, when the nozzles 21 formed in these ejection heads 22 are projected in the transport direction F, the nozzles 21 that eject ink of each color are arranged at equal intervals in the width direction X.

  Further, one or more nozzles 21 counted from the second end side of the nozzle row 27 of the first ejection head 221 and one or more nozzles 21 counted from the first end side of the nozzle row 27 of the second ejection head 222. Are overlapped when projected in the transport direction F. Specifically, the (n−1) th nozzle 21 (n−1) of the first ejection head 221, the first nozzle 21 (1) of the second ejection head 222, and the nth nozzle of the first ejection head 221. 21 (n) and the second nozzle 21 (2) of the second ejection head 222 are formed so as to overlap when projected in the transport direction F. This is because the nozzle 21 on the second end side of the second ejection head 222 and the nozzle 21 on the first end side of the third ejection head 223 and the nozzle 21 on the second end side of the third ejection head 223 and the fourth one. The same applies to the nozzle 21 on the first end side of the discharge head 224.

  In the following description, the nozzles 21 formed so as to overlap when projected in the transport direction F in the ejection heads 22 provided adjacent to each other in the width direction X are also referred to as “overlapping nozzles”. For example, the nozzle 21 (n−1) and the nozzle 21 (n) of the first ejection head 221 and the nozzle 21 (1) and the nozzle 21 (2) of the second ejection head 222 are connected to the first ejection head 221 and the nozzle 21 (n). This is an overlapping nozzle of the second ejection head 222.

  Thus, in the present embodiment, in the width direction X, ink can be ejected from the overlapping nozzles of any ejection head 22 to the medium S that is transported in the area facing the area where the adjacent ejection heads 22 overlap. it can. However, in this embodiment, it is assumed that ink is ejected from only one of the overlapping nozzles. That is, in the present embodiment, in the normal case, the first ejection head 221 ejects ink from the first nozzle (1) to the (n-1) th nozzle 21 (n-1), and the second ejection. The head 222 ejects ink from the second nozzle (2) to the (n-1) th nozzle 21 (n-1). The third ejection head 223 ejects ink from the second nozzle (2) to the (n-1) th nozzle 21 (n-1), and the fourth ejection head 224 is ejected from the second nozzle (2). It is assumed that ink is ejected to the nth nozzle 21 (n).

Next, the internal configuration of the ejection head 22 will be described with reference to FIG.
As shown in FIG. 4, the actuator 43 includes a piezoelectric element 44, and the wall of the cavity 42 in contact with the piezoelectric element 44 is a vibrating wall 45 that can be flexed and displaced in a direction to increase or decrease the volume of the cavity 42.

  When the piezoelectric element 44 is contracted and deformed by energization, the vibration wall 45 of the cavity 42 is elastically deformed in the direction of increasing the volume of the cavity 42 as shown by a two-dot chain line in FIG. When the volume of the cavity 42 increases, the ink stored in the common liquid chamber 41 is introduced into the cavity 42. Thereafter, when energization is stopped, the vibration wall 45 of the cavity 42 in contact with the piezoelectric element 44 is elastically moved in the direction of decreasing the volume of the cavity 42 as shown by a one-dot chain line in response to the recoil of the contraction of the piezoelectric element 44. Deform.

  Then, the volume of the cavity 42 is rapidly reduced, whereby the ink in the cavity 42 is pushed into the nozzle 21 and the pushed ink is ejected as a droplet from the nozzle 21. After the ink is ejected, the nozzle 21 is replenished with ink for the ejected droplets from the cavity 42 on the upstream side by capillary force.

  A capillary force acts on the nozzle 21 which is a hole having a thin tubular shape. For this reason, in a state where the actuator 43 is not driven, a meniscus M which is a liquid surface having a concave shape is formed in the nozzle opening which is a downstream opening on the nozzle forming surface 28 of the nozzle 21.

Next, the pressure adjustment mechanism 25 will be described with reference to FIGS. 2, 4, and 5.
As shown in FIGS. 2 and 4, the pressure adjusting mechanism 25 is provided in the middle of the liquid supply path 32 communicating with the common liquid chamber 41, and adjusts the pressure of the ink in the nozzles 21 for each nozzle row 27.

  As shown in FIG. 4, the pressure adjusting mechanism 25 includes a pressure chamber 52, a supply chamber 53, a valve body 54, and a supply chamber in which a movable wall 51 that can be displaced in a direction in which the volume is changed constitutes a part of the wall surface. A first urging member 55 that urges the valve body 54 in the inside 53, and a second urging member 56 that urges the movable wall 51 in the pressure chamber 52 toward the outside of the pressure chamber 52.

  The pressure chamber 52 has an inflow hole 57 for allowing the ink to be supplied under pressure to flow into a position different from the movable wall 51, and an outflow hole 58 communicating with the nozzle 21 (nozzle row 27) via the common liquid chamber 41. Have. The supply chamber 53 can communicate with the pressure chamber 52 via the inflow hole 57. The valve body 54 has a proximal end portion disposed in the supply chamber 53 and a distal end portion protruding into the pressure chamber 52 through the inflow hole 57. The valve body 54 has a closed position (position shown in FIG. 4) where the seal portion 541 provided at the base end closes the inflow hole 57 and an open position (position shown in FIG. 5) where the inflow hole 57 is opened. The first urging member 55 accommodated in the supply chamber 53 is urged toward the closed position in a displaceable state. The second urging member 56 has one end in contact with the pressure receiving plate 59 attached to the movable wall 51 and the other end disposed so as to surround the distal end portion of the valve body 54 protruding into the pressure chamber 52.

  In addition, the pressure adjusting mechanism 25 applies an external force to the movable wall 51 from the outside of the pressure chamber 52 in the direction of decreasing the volume of the pressure chamber 52, thereby allowing the pressure chamber 52 and the nozzle 21 communicating with the pressure chamber 52 to communicate with each other. A pressure-increasing mechanism 62 for increasing the pressure is provided. The pressure increase mechanism 62 may employ a mechanism that converts the rotational movement of the motor into a movement that pushes the movable wall 51, such as a cam mechanism, or the movable wall by increasing the pressure in the space outside the pressure chamber 52. A mechanism for pressing 51 may be adopted.

  The valve element 54 of the pressure adjusting mechanism 25 is urged by the first urging member 55 accommodated in the supply chamber 53 so that it does not move to the open position even if the pressure in the supply chamber 53 rises. On the other hand, when the pressure in the pressure chamber 52 becomes lower than a predetermined pressure due to the outflow of ink from the outflow hole 58, the movable wall 51 is displaced toward the inside of the pressure chamber 52, and the pressure receiving plate 59 is moved to the tip of the valve body 54. By pushing, the valve body 54 moves to the open position. As a result, the pressurized ink in the supply chamber 53 flows into the pressure chamber 52 through the inflow hole 57, so that the pressure in the pressure chamber 52 increases.

  When the movable wall 51 is displaced toward the outside of the pressure chamber 52 due to the pressure increase in the pressure chamber 52 and the pressure receiving plate 59 is separated from the tip of the valve body 54, the valve body 54 moves from the open position to the closed position. . Here, the second urging member 56 pushes back the pressure receiving plate 59 in a direction away from the tip of the valve body 54 when the pressure receiving plate 59 approaches the tip of the valve body 54.

  Therefore, when the pressure in the pressure chamber 52 decreases and the pressure receiving plate 59 presses the tip of the valve body 54 against the biasing force of the first biasing member 55 and the second biasing member 56, the valve body 54 is Move to the open position. Further, the pressure receiving plate 59 is separated from the valve body 54 by the urging force of the second urging member 56 before the pressure in the pressure chamber 52 rises to a positive pressure due to the inflow of ink, so the pressure in the pressure chamber 52 is The negative pressure range corresponding to the biasing force of the second biasing member 56 is maintained.

  Thus, the movement of the valve body 54 to the open position occurs due to the displacement of the movable wall 51. And the outer surface side of the movable wall 51 is open | released by air | atmosphere. Therefore, the movement of the valve body 54 to the open position is performed without using a driving force such as a motor due to the differential pressure between the atmospheric pressure and the pressure chamber 52. The part to be excluded is also referred to as a differential pressure valve mechanism 61 (or a self-sealing valve), and an autonomous pressure adjustment function by the differential pressure valve mechanism 61 is also referred to as a self-sealing function.

  As described above, the pressure adjusting mechanism 25 can regulate the flow of the ink supplied under pressure by the supply mechanism 24 to the ejection head 22 and can reduce the pressure of the ink on the downstream side where the flow is regulated to a predetermined negative value. The pressure can be maintained within a range.

  That is, in the pressure adjusting mechanism 25, when ink is ejected, the ink flows out from the outflow hole 58, and the pressure in the pressure chamber 52 decreases below a predetermined pressure lower than the atmospheric pressure. Then, the movable wall 51 that is displaced in the direction of decreasing the volume of the pressure chamber 52 moves the valve body 54 to the open position. Accordingly, the pressurized ink from the inflow hole 57 flows into the pressure chamber 52 and the pressure in the pressure chamber 52 increases. Further, when the pressure in the pressure chamber 52 becomes equal to or higher than a predetermined pressure less than the atmospheric pressure due to the supply of the pressurized ink, the valve body 54 restricts the flow of ink from the upstream side again.

  When an external force is applied to the ejection head 22, the meniscus M formed on the nozzle 21 may be broken by the impact, and ink may leak from the nozzle 21. In order to suppress such ink leakage, the pressure adjustment mechanism 25 holds the pressure chamber 52 located upstream of the nozzle 21 at a predetermined negative pressure by the urging force of the second urging member 56, and The pressure resistance of the formed meniscus M is increased.

  Further, the pressure adjusting mechanism 25 performs a pressure increasing operation for increasing the pressure of the ink in the nozzle 21 so that the liquid level swells from the nozzle 21 by driving the pressure increasing mechanism 62. As shown in FIG. 5, in the pressure increasing operation, the valve body 54 is moved to the open position by displacing the movable wall 51 in the direction in which the volume of the pressure chamber 52 decreases by driving the pressure increasing mechanism 62. Then, after a predetermined time, the valve body 54 is returned to the closed position by displacing the movable wall 51 in a direction in which the volume of the pressure chamber 52 increases. As a result, the pressurized ink flows into the pressure chamber 52 by a predetermined amount, and the pressure of the ink in the nozzle 21 increases. That is, the internal pressure that is the pressure of the ink in the nozzle 21 is higher than the external pressure that is the pressure in the space in which the nozzle 21 opens (in this embodiment, atmospheric pressure). As shown in FIG. 5, the pressure increase (amount of ink to flow) at this time is such that the meniscus M swells outside the nozzle opening, but the ink droplet does not fall from the nozzle 21. preferable.

Next, a maintenance device 26 as an example of a maintenance unit and maintenance of the discharge head 22 by the maintenance device 26 will be described with reference to FIG.
In the printing apparatus 11, maintenance such as flushing, capping, suction cleaning, and wiping is performed in the ejection head 22 in order to prevent or eliminate ejection failure caused by clogging of the nozzle 21 or adhesion of foreign matter. The maintenance device 26 includes a cap 81 configured to perform capping, a suction mechanism 82 configured to perform suction cleaning using the cap 81, and a wiping unit 83 configured to perform wiping. Prepare.

  Flushing discharges (discharges) droplets from the nozzles 21 regardless of printing, thereby removing foreign matter, bubbles, or altered ink (for example, ink thickened by evaporation of solvent components) that causes discharge failure. To be discharged. Ink discharged as waste liquid by flushing may be received by the cap 81, or a flushing box for receiving waste liquid generated by flushing may be separately provided. Further, the cap 81 may be provided for each ejection head 22, or may be provided for each ejection head 22 for each nozzle row 27 (each ink type).

  The cap 81 is configured to move between a capping position that surrounds and forms a space where the nozzle 21 of the ejection head 22 opens as a closed space, and a separation position where the space where the nozzle 21 opens is an open space. The Then, capping is performed by placing the cap 81 at the capping position. When ink is not ejected, the capping is performed to suppress drying of the nozzles 21 and prevent the occurrence of ejection failure. Further, when the waste ink generated by the flushing is received, the cap 81 is disposed at the separated position. Although illustration is omitted, the plurality of caps 81 are alternately arranged in the width direction X and the conveyance direction F so that the plurality of ejection heads 22 can be capped.

  The suction mechanism 82 includes a suction tube 84 whose upstream end is connected to the cap 81, a waste liquid storage portion 85 into which the downstream end of the suction tube 84 is introduced, a decompression pump 86 provided in the middle of the suction tube 84, The suction tube 84 includes a pressure reducing valve 87 (switching valve) provided between the pressure reducing pump 86 and the cap 81.

  Then, by applying a negative pressure generated by driving the decompression pump 86 to a closed space formed by arranging the cap 81 at the capping position, suction cleaning is performed in which ink is sucked and discharged from the nozzle 21 by the negative pressure. Is done. The ink discharged from the nozzle 21 by the suction cleaning is stored in the waste liquid storage unit 85 as a waste liquid. Note that the cap 81 also functions as a part of the suction mechanism 82 when performing the suction cleaning. In the present embodiment, the suction cleaning is performed on all the ejection heads 22.

  The wiping unit 83 includes a wiping unit 88 that wipes the nozzle forming surface 28 of the ejection head 22, a holding unit 89 that holds the wiping unit 88, and a guide shaft 91 that guides the movement of the holding unit 89 along the nozzle forming surface 28. , And a drive unit 92 for moving the holding unit 89 along the nozzle forming surface 28.

  The wiping portion 88 is configured by an absorbing member such as a plate member made of an elastically deformable resin or a cloth capable of absorbing ink. When the driving unit 92 is driven, the wiping unit 88 moves together with the holding unit 89 in a state in which the wiping unit 88 is in contact with the ejection head 22 with a predetermined contact pressure. Accordingly, wiping is performed in which the wiping unit 88 wipes the ejection head 22 around the nozzle formation surface 28. The wiping unit 88 sequentially wipes the nozzle forming surfaces 28 of the plurality of ejection heads 22 while moving in the width direction X of the medium S.

  At the start of use of the printing apparatus 11, first, after the gas delivery path 35 is set to a positive pressure by driving the pressurizing pump 37, the suction cleaning is executed, so that the ink from the liquid outlet path 34 to the nozzle 21 is discharged. Fill the flowing area with ink. This is called “initial filling”. Then, after the initial filling is performed, wiping is performed in order to wipe off ink adhering to the nozzle forming surface 28, and further, flushing is performed in order to prepare the meniscus M. Thus, it is preferable to sequentially perform wiping and flushing after suction cleaning.

Next, the electrical configuration of the printing apparatus 11 will be described with reference to FIG.
As illustrated in FIG. 6, the control unit 100 includes a storage unit 101 that stores various setting information of the printing apparatus 11 and programs executed by the control unit 100. In this respect, in the present embodiment, the control unit 100 is a microcomputer including a CPU, a ROM, a RAM, and the like.

  The printing apparatus 11 also includes a detection unit 95 that detects an electrical signal (voltage signal) output from the actuator 43 in the ejection head 22 and a conveyance unit 96 that conveys the medium S from the feeding cassette 14 to the first discharge tray 15. And a FAX communication unit 97 that performs FAX transmission / reception. A detection unit 95 is connected to the input side interface of the control unit 100, and the pressurization valve 36, the pressurization pump 37, the actuator 43, the pressure increasing mechanism 62, the transport unit 96, and the output side interface of the control unit 100 are connected. A cap 81, a decompression pump 86, a decompression valve 87, and a drive unit 92 are connected.

  Then, the control unit 100 performs printing on the medium S by controlling the driving of various components including the ejection head 22 and the conveyance unit 96 based on a print job as an example of a “liquid ejection command”. . Note that in a so-called line head type printer such as the printing apparatus 11 of the present embodiment, printing is performed by ejecting ink onto the medium S being conveyed while maintaining a predetermined conveyance speed.

  Further, when printing is continuously performed on a plurality of media S, ink is ejected onto the plurality of media S that are sequentially transported at a predetermined transport speed. Here, when printing is continuously performed on a plurality of media S, from the start of printing on one of the plurality of media S to the end of printing on the one medium S. Ink is ejected, but ink is not ejected until printing on the next medium S is started after printing on one medium S is completed.

  In other words, ink is ejected or not ejected from the ejection head 22 during the transport period in which the plurality of media S are sequentially transported. Therefore, when printing is continuously performed on a plurality of media S, the conveyance period of the medium S when printing is performed on the medium S is referred to as an “ejection conveyance period”, and the medium S is printed. The conveyance period of the medium S when printing is not performed is referred to as a “non-ejection conveyance period”.

  Further, the control unit 100 causes the ejection failure detection of the nozzle 21 and the maintenance of the ejection head 22 to be executed. Here, the maintenance executed by the control unit 100 includes “automatic maintenance” that is automatically executed when a predetermined condition is satisfied and “manually executed” based on a maintenance command from the user of the printing apparatus 11. There is "manual maintenance". That is, automatic maintenance is maintenance performed based on the determination of the control unit 100 regardless of the user's intention, and manual maintenance is maintenance performed based on the user's intention.

  Next, a nozzle check for determining whether or not ejection failure has occurred in the nozzles 21 formed in the ejection head 22 will be described. The nozzle check of the present embodiment includes a first nozzle check that does not involve user judgment and a second nozzle check that involves user judgment.

First, the first nozzle check will be described with reference to FIG.
As shown in FIG. 4, in this embodiment, the vibration wall 45 provided in the ejection head 22 is attenuated until the next drive voltage is applied when the drive voltage is applied to the actuator 43. However, it vibrates (residual vibration). As described above, when the vibration wall 45 vibrates, the actuator 43 generates an electric signal corresponding to the residual vibration of the vibration wall 45, contrary to the case where the vibration wall 45 is vibrated with the application of the drive voltage. Output.

  Further, the vibration mode of the residual vibration in the nozzle 21 (hereinafter also referred to as “normal nozzle”) in which no ejection failure has occurred and the vibration of the residual vibration in the nozzle 21 in which ejection failure has occurred (hereinafter also referred to as “defective nozzle”). Different from the embodiment. Specifically, when bubbles are mixed in the nozzle 21, the residual vibration of the vibration wall 45 is less than when the bubbles are not mixed in the nozzle 21 (when the state of the nozzle 21 is good). The frequency tends to be high. Further, when the ink is thickened in the nozzle 21, the residual vibration of the vibration wall 45 is compared with the case where the ink is not thickened in the nozzle 21 (when the state of the nozzle 21 is good). Tend to be lower.

  Therefore, the electric signal of the actuator 43 output according to the residual vibration of the vibration wall 45 accompanying the driving of the piezoelectric element 44 is detected by the detection unit 95, and the control unit 100 compares the frequency of the electric signal with the normal frequency. Thus, it is possible to determine whether the nozzle 21 to be inspected is a normal nozzle or a defective nozzle. In this respect, in this embodiment, the control unit 100, the detection unit 95, and the actuator 43 constitute an example of the “ejection failure detection unit”. It should be noted that the normal residual vibration frequency may be stored in the storage unit 101.

  Further, since the nozzle 21, the actuator 43, and the vibration wall 45 are provided in a 1: 1 relationship, when the first nozzle check is executed for all the nozzles 21, the actuator 43 is driven at different timings. The nozzles 21 to be inspected are sequentially switched.

  The first nozzle check described above can detect the presence or absence of a defective nozzle at high speed without consuming ink by driving the actuator 43 to such an extent that ink is not ejected from the nozzle 21. On the other hand, in the first nozzle check, when foreign matters such as paper dust adhere to the nozzle forming surface 28 of the ejection head 22 so as to close the nozzle 21 without touching the meniscus M of the nozzle 21. May not be able to detect a discharge failure of the nozzle 21. In other words, the first nozzle check detects ejection failure based on a change in residual vibration of the vibration wall 45 in accordance with a change in the state of ink in the nozzle 21, and thus comes into contact with the ink in the nozzle 21. In the case where the ejection of the ink ejected from the nozzle 21 is hindered, the ejection failure of the nozzle 21 may not be detected.

  Thus, in the first nozzle check, it is possible to detect a defective nozzle, but in reality, there is a possibility that the nozzle 21 in which the ejection failure has occurred is erroneously detected as a normal nozzle. In the following description, the nozzle 21 in which ejection failure is detected by the first nozzle check is referred to as “defective nozzle”, and the nozzle 21 in which ejection failure is not detected is referred to as “normal nozzle”. The nozzle 21 in which a discharge failure has actually occurred although no discharge failure has been detected by the first nozzle check is referred to as a “true defective nozzle”.

Next, the second nozzle check will be described with reference to FIG.
The printing apparatus 11 according to the present embodiment performs ejection based on a pattern printing command (pattern formation command) from the user in order to check whether ink is being ejected normally from the ejection head 22 toward the medium S. A pattern for confirming ejection failure (hereinafter also referred to as “nozzle check pattern PT”) is printed from the nozzle 21 of the head 22 toward the medium S.

  As shown in FIG. 7, in the case of the line head type printing apparatus 11 as in the present embodiment, a belt-like nozzle check pattern PT is printed for each color in the width direction X. That is, the nozzle check patterns PTc, PTm, PTy, and PTk for confirming the ejection failure of the nozzles 21c, 21m, 21y, and 21k that eject cyan ink, magenta ink, yellow ink, and black ink are arranged in the transport direction F. Printed.

  For example, when an ejection failure occurs in the nozzle 21m formed on the first end side among the nozzles 21m that eject magenta ink of the first ejection head 221, a nozzle check pattern PTm as shown in FIG. 7 is printed. . Further, when a discharge failure occurs in the nozzle 21k formed near the center in the width direction X among the nozzles 21k that discharge the black ink of the third discharge head 223, a nozzle check pattern PTk as shown in FIG. 7 is printed. Is done. In this way, by printing the nozzle check pattern PT, the user can determine which nozzle 21 has an ejection failure.

  Therefore, the second nozzle check is performed by printing the nozzle check pattern PT and determining whether there is a nozzle 21 in which ejection failure has occurred based on the printed nozzle check pattern PT.

  Further, when printing the nozzle check pattern PT, it is assumed that ink is ejected from only one nozzle 21 among the overlapping nozzles of the ejection heads 22 adjacent in the width direction X, as in printing based on a print job. This is because, when ink is ejected from both nozzles 21 of the overlapping nozzle, among the overlapping nozzles, even if ejection failure occurs in the nozzle 21 that is to eject ink during printing, the other nozzle 21 This is because the ejection failure of the former nozzle 21 may be missed due to the ejection of ink from the first nozzle 21. For example, when ejection failure occurs in the (n−1) th nozzle 21k (n−1) of the first ejection head 221, ink is ejected from the first nozzle 21k (1) of the second ejection head 222. This is because the former nozzle 21k (n-1) may miss a discharge failure.

  Thus, since the second nozzle check actually prints the nozzle check pattern PT on the medium S, it takes time to detect ejection failure and consumes ink. On the other hand, since the nozzle check pattern PT is printed under the same conditions as when printing based on the print job, there is less possibility of missing a defective nozzle that affects the print quality. That is, in the second nozzle check, there is a high possibility that a true defective nozzle that cannot be detected by the first nozzle check can be detected.

Next, with reference to FIG. 8 and FIG. 9, a complementary process for complementing the ink ejection from the defective nozzle with the ink ejection from the normal nozzle will be described.
As shown in FIG. 8, for example, when there is no defective nozzle among all the nozzles 21 from the i-3 nozzle 21 (i-3) to the i + 3 nozzle 21 (i + 3) of a certain discharge head 22. These nozzles 21 can eject ink droplets Id to the medium S without any gap.

  However, when the i-th nozzle 21 (i) is a defective nozzle, the i-th nozzle 21 (i) cannot eject the ink droplet Id to the medium S without a gap. Therefore, when printing is performed even though the i-th nozzle 21 (i) is a defective nozzle, ink is applied to a region on the medium S where the i-th nozzle 21 (i) should eject ink. By not discharging, the print quality deteriorates. Therefore, it is conceivable to perform maintenance in order to suppress a decrease in print quality. However, if maintenance is performed every time a defective nozzle occurs, loss time during which printing cannot be performed increases as the maintenance is performed. There is a fear.

  Therefore, in the present embodiment, when it is possible to complement the ink ejection from the defective nozzle with the ink ejection from the normal nozzle, printing is performed after performing the complementation, thereby reducing the print quality. We decided to suppress the increase in downtime. In the present embodiment, there are three complementing methods, “neighboring complementing”, “alternative complementing”, and “mixed color complementing”, depending on the complementing method.

First, neighborhood complement will be described.
As shown in FIG. 8, when there is a defective nozzle (nozzle 21 (i)) in the nozzle row 27 of the ejection head 22, the proximity complement is performed on both adjacent nozzles (nozzles 21 (i−1), 21 (I + 1)) The ink discharge amount is increased. In this way, the situation where the ink droplet Id is not ejected to the area on the medium S where the defective nozzle should eject ink is suppressed.

  However, the following problems may occur only by increasing the ink discharge amount of the nozzles adjacent to the defective nozzle (nozzles 21 (i-1), 21 (i + 1)). That is, the ink droplet Id ejected by the nozzles adjacent to the defective nozzle (nozzles 21 (i-1) and 21 (i + 1)) and the nozzle (nozzle adjacent to the defective nozzle as viewed from the nozzles 21 adjacent to the nozzle) 21 (i-2), 21 (i + 2)) increases the area where the ink droplet Id ejected on the medium S overlaps, which may affect the print quality.

  Therefore, when the ink discharge amount of the nozzles 21 (nozzles 21 (i-1) and 21 (i + 1)) on both sides of the defective nozzle is increased, the side opposite to the defective nozzle as viewed from the nozzles 21 on both sides. It is desirable to reduce the ink discharge amount of the adjacent nozzles 21 (nozzles 21 (i-2), 21 (i + 2)). According to this, the ink droplets Id ejected by the nozzles 21 adjacent to the defective nozzles and the ink droplets Id ejected by the nozzles 21 adjacent to the nozzles on the side opposite to the defective nozzles 21 are on the medium S. Thus, an increase in overlapping area is suppressed, and a decrease in print quality is suppressed.

  Thus, near complement is to complement the ink ejection from the defective nozzle with the ink ejection from the nozzle 21 in the vicinity of the defective nozzle. For this reason, proximity complement can be performed for all nozzles.

Next, alternative complement will be described.
As shown in FIG. 9, in this embodiment, the ejection heads 22 adjacent in the width direction X have overlapping nozzles. For this reason, even if it is a case where the overlap nozzle of one discharge head 22 becomes a defective nozzle among the two discharge heads 22 which have an overlap nozzle, ink can be discharged from the overlap nozzle of the other discharge head 22. it can.

  For example, when the (n−1) th nozzle 21 (n−1) of the second ejection head 222 becomes a defective nozzle, the first nozzle 21 (1) of the third ejection head 223 causes the ink to be discharged. Dispensing can be complemented. In addition, when the second nozzle 21 (2) of the third ejection head 223 becomes a defective nozzle, the nth nozzle 21 (n) of the second ejection head 222 supplements ink ejection. be able to.

  In this way, substitution complement means that one of the two overlapping nozzles formed so as to overlap when projected in the transport direction F in the two ejection heads 22 adjacent in the width direction X is a defective nozzle. Sometimes, the ejection of ink from the one nozzle 21 is complemented by the ejection of ink from the other nozzle 21. For this reason, alternative supplementation cannot be performed for the nozzles 21 that are not overlapping nozzles.

Finally, color mixing complement will be described.
In the printing apparatus 11 capable of ejecting cyan ink, yellow ink, and magenta ink as color inks as in this embodiment, black is expressed by ejecting these color inks so as to overlap on the medium S. Can do. That is, even when a discharge failure occurs in the nozzle 21 that discharges black ink, the nozzles 21c, 21m, and 21m that discharge the color ink formed so as to overlap with the defective nozzle when projected in the transport direction F. This can be complemented by ejecting ink from 21y.

  For example, as shown in FIG. 9, when the i-th nozzle 21k (i) that discharges black ink in the third discharge head 223 becomes a defective nozzle, the ink is discharged from the defective nozzle to the third This can be complemented by discharge of cyan ink, magenta ink, and yellow ink from the i-th nozzle 21c (i), 21m (i), 21y (i) of the discharge head 223.

  In this way, the color mixture complementation complements the ejection of ink from the defective nozzle with the ejection of ink from the nozzles 21c, 21m, and 21y that eject color ink when the nozzle 21k that ejects black ink becomes a defective nozzle. To do. For this reason, color mixture complementation cannot be performed for the nozzles 21 that discharge color ink.

  As described above, in the present embodiment, the control unit 100 can perform three types of complementation. Whether or not complementation is possible is determined for each defective nozzle by the control unit 100. In addition, when the vicinity complement can be performed for a certain defective nozzle, the control unit 100 does not perform substitution complementation and color mixing complement for the defective nozzle. In addition, when the alternative complement can be performed for a certain defective nozzle, the control unit 100 does not perform the color mixture complement for the defective nozzle. That is, in the present embodiment, the priority order of complementation is determined in the order of neighborhood complement, alternative complement, and color mixture complement. Further, if any supplement can be performed on the defective nozzle, the control unit 100 determines that the defective nozzle can be supplemented.

  Note that the complementing process is performed for each defective nozzle, and the supplementary content does not change based on the content of the print job. For this reason, a complement process can be performed only based on the result of a 1st nozzle check.

Next, the maintenance for recovering the defective ejection of the defective nozzle will be described.
As described above, in the printing apparatus 11 according to the present embodiment, as maintenance performed to eliminate defective ejection of a defective nozzle, ink is applied from the nozzle 21 by applying a negative pressure to the closed space formed by capping. It is possible to perform “suction cleaning” for forcibly sucking the water.

  When performing suction cleaning, the ink suction time is increased by increasing the time during which negative pressure is applied to the closed space formed by capping, or the negative pressure applied to the closed space is increased. Thus, by increasing the ink suction speed, it is possible to improve the ability to recover the ejection failure of the defective nozzle. That is, when suction cleaning is executed, the ability to recover the ejection failure for the defective nozzle can be changed by controlling the driving of the decompression pump 86.

  In the following description, for easy understanding, suction cleaning with a relatively low ability to recover ejection failure is also referred to as weak cleaning, and suction cleaning with a moderate ability to recover ejection failure is also referred to as intermediate cleaning. Suction cleaning with a relatively high ability to recover from defects is also called strong cleaning. Also, maintenance (suction cleaning) that has a high ability to recover defective discharge from defective nozzles is also called “high-strength maintenance”, and maintenance that has a low ability to recover defective discharge from defective nozzles is called “low-strength maintenance”. " That is, it can be said that the maintenance device 26 of the present embodiment can change the strength of maintenance.

  By the way, there is a proportional relationship between the amount of ink consumed in performing maintenance and the ability to recover ejection failure (maintenance strength). That is, the higher the intensity of maintenance, the easier the ink consumption associated with the execution of the maintenance, and the lower the intensity of maintenance, the easier the ink consumption associated with the execution of the maintenance.

  For this reason, even though the number of defective nozzles is small and a light ejection failure has occurred, when high-strength maintenance is performed, ink is consumed in excess of that required to recover the light ejection failure. There is a risk. Moreover, even if the number of defective nozzles is large and a severe discharge failure has occurred, if maintenance with low strength is performed, the severe discharge failure may not be recovered even if the maintenance is performed.

  Therefore, in the present embodiment, the control unit 100 selects the maintenance intensity based on the result of the first nozzle check. Specifically, in the case where manual maintenance is performed, the control unit 100 determines that the maintenance strength is lower when a defective nozzle is not detected than when a defective nozzle is detected. In addition, when performing automatic maintenance and manual maintenance, the control unit 100 determines that the maintenance strength is lower when the number of defective nozzles is smaller than when the number of defective nozzles is large.

  In this embodiment, the number of defective nozzles detected by the first nozzle check and the ratio of the defective nozzles that can be complemented are changed from “0 (zero)” to “3”. The ejection failure level Lv expressed in the four stages is set. And the intensity | strength in the case of performing maintenance is changed according to the discharge defect level Lv.

  Here, the ejection failure level Lv in the present embodiment is set for each ink color. When the discharge failure level Lv is “0 (zero)”, no discharge failure has occurred, and when the discharge failure level Lv is “1”, a mild discharge failure has occurred. When the discharge failure level Lv is “2”, a medium discharge failure occurs. When the discharge failure level Lv is “3”, a severe discharge failure occurs. Is the case.

  Specifically, the case where the ejection failure level Lv is “0 (zero)” is the case where the failure nozzle is “0 (zero)”, and the case where the ejection failure level Lv is “1” to “3”. Is a case where a defective nozzle of “1” or more has occurred. The case where the ejection failure level Lv is “1” is a case where all the defective nozzles can be complemented, and the case where the ejection failure level Lv is “2” or “3” This is a case where the nozzle cannot be complemented.

  Furthermore, the case where the ejection failure level Lv is “2” is the case where the number of defective nozzles in one nozzle row 27 is less than the specified number of nozzles, and the case where the ejection failure level Lv is “3” is 1 This is a case where the number of defective nozzles in one nozzle row 27 is greater than or equal to the specified number of nozzles. The prescribed number of nozzles is a predetermined number (for example, 10%) of the number of nozzles 21 constituting one nozzle row 27.

  Thus, in the present embodiment, the control unit 100 can also be said to lower the maintenance intensity when the ejection failure level Lv is low than when the ejection failure level Lv is high during maintenance.

  Next, a processing routine executed by the control unit 100 to perform initial filling will be described with reference to the flowchart shown in FIG. This processing routine is a processing routine that is executed each time the liquid supply source 23 is attached.

  As shown in FIG. 10, in this processing routine, the control unit 100 performs initial filling (step S11). That is, the control unit 100 controls the driving of the pressurizing valve 36 and the pressurizing pump 37 to pressurize and supply ink from the liquid supply source 23 toward the downstream side. In addition, the control unit 100 controls the driving of the cap 81, the pressure reducing pump 86, and the pressure reducing valve 87 to execute suction cleaning. In this way, the ink supplied from the liquid supply source 23 reaches the nozzle 21 of the ejection head 22, and the ink supply path in the printing apparatus 11 is filled with ink. When the initial filling is completed, the control unit 100 executes an automatic maintenance process (step S12), and sets a reception state in which a print job can be received (step S13). Then, the control part 100 once complete | finishes this process routine.

  Next, a processing routine executed by the control unit 100 at the start of printing will be described with reference to a flowchart shown in FIG. This processing routine is a processing routine that is executed every time a print job is input to the printing apparatus 11.

  As shown in FIG. 11, in this processing routine, the control unit 100 determines whether or not the automatic maintenance flag is on (step S21). If the automatic maintenance flag is on (step S21: YES), the automatic maintenance processing is performed. Is executed (step S22). Here, the automatic maintenance flag is a flag for selecting whether or not to execute the automatic maintenance process, and can be set by the user via the display unit 13. Thereafter, the control unit 100 performs printing based on the input print job (step S23), and once ends this processing routine.

  On the other hand, in the previous step S21, when the automatic maintenance flag is OFF (step S21: NO), the control unit 100 executes the flushing (step S24) and executes the first nozzle check (step S25). And the control part 100 performs a complementation process about the detected defective nozzle (step S26), and transfers the process to step S23. That is, in this case, printing is performed without executing the automatic maintenance process. Further, in this case, in step S26, the detected defective nozzles are complemented for the defective nozzles that can be complemented, and the defective nozzles that cannot be complemented are not complemented.

  Next, a processing routine executed by the control unit 100 during printing based on a print job will be described with reference to a flowchart shown in FIG. This processing routine is a processing routine that is executed in a predetermined control cycle during printing based on a print job.

  As shown in FIG. 12, in this processing routine, the control unit 100 determines whether or not it is a non-ejection conveyance period that is a conveyance period not accompanied by ink ejection (step S31). (Step S31: NO), this processing routine is once ended. On the other hand, when it is a non-ejection conveyance period (step S31: YES), the control part 100 performs a 1st nozzle check (step S32). And the control part 100 performs a complementation process about the detected defective nozzle (step S33), and complete | finishes this actual process routine once. Note that in step S33, of the detected defects, complementation is performed for defective nozzles that can be complemented, and supplementation is not performed for defective nozzles that cannot be complemented.

  Further, according to the above processing routine, in the non-ejection conveyance period, the complementary processing that does not require a relatively long time is executed, but the maintenance that requires a relatively long time is not executed. For this reason, while performing printing on a plurality of media S based on one print job, an increase in loss time due to the execution of maintenance is suppressed, while a decrease in print quality is suppressed by executing complement processing. Is done.

  In the flowchart shown in FIG. 12, the first nozzle check in step S32 is performed after printing on the medium S and before printing on the next medium S is started. In this regard, in this embodiment, step S32 corresponds to an example of “detection of discharge failure between media” that detects a discharge failure of the nozzle 21 every time printing on the medium S is completed.

  Next, a processing routine executed by the control unit 100 after completion of printing based on the print job will be described with reference to a flowchart shown in FIG. This processing routine is a processing routine that is executed every time printing based on a print job is completed.

  As shown in FIG. 13, in this processing routine, the control unit 100 determines whether or not the number of printed sheets Pn of the medium S since the most recent maintenance is equal to or greater than the specified number of sheets PnTh (step S41). Here, the specified number of sheets PnTh means that foreign matter (for example, paper dust) adheres to the nozzle formation surface 28 of the ejection head 22 by continuing printing on the medium S without performing maintenance, thereby affecting print quality. This is the number of printed sheets of the medium S at the start of giving.

  If the number of printed sheets Pn is equal to or greater than the specified number of sheets PnTh (step S41: YES), the control unit 100 executes periodic maintenance (step S42), and once ends this processing routine. In other words, when it is clear that the print quality is deteriorated regardless of the state of the automatic maintenance flag, the periodic maintenance is executed. The regular maintenance may be performed with cleaning that can achieve the purpose of removing the foreign matter adhering to the nozzle forming surface 28.

  On the other hand, when the number of printed sheets Pn is less than the specified number of sheets PnTh (step S41: NO), the control unit 100 determines whether or not the automatic maintenance flag is on (step S43), and when the automatic maintenance flag is on (step S43). S43), an automatic maintenance process is executed (step S44). Then, the control part 100 once complete | finishes this process routine. On the other hand, in the previous step S43, when the automatic maintenance flag is off (step S43: NO), the control unit 100 once ends this processing routine.

  Next, a processing routine executed by the control unit 100 in order to execute the automatic maintenance processing in steps S12, S22, and S44 will be described with reference to the flowchart shown in FIG.

  As shown in FIG. 14, the control unit 100 sets “0 (zero)” to the first counter Cnt1 and the second counter Cnt2 (step S51). The first counter Cnt1 counts the number of times maintenance has been performed to recover the discharge failure, and the second counter Cnt2 indicates that a discharge failure with a severe discharge failure level Lv has occurred “3”. It counts the number of times it was.

  Subsequently, the control unit 100 executes a discharge failure level determination process (step S52), and determines whether or not the determined discharge failure level Lv is “0 (zero)” (step S53). When the ejection failure level Lv is “0 (zero)” (step S53: YES), since the defective nozzle is not detected and there is no need to perform maintenance, the control unit 100 once ends this processing routine. .

  On the other hand, when the discharge failure level Lv is not “0 (zero)” (step S53: NO), the control unit 100 determines whether or not the discharge failure level Lv is “1” (step S54), and discharge failure. If the level Lv is “1” (step S54: YES), the complementing process is executed without executing maintenance (step S55). When step S54 is affirmed and step S55 is executed, since the ejection failure level Lv is “1”, all the defective nozzles are complemented.

  On the other hand, when the ejection failure level Lv is not “1” (step S54: NO), that is, when there is a defective nozzle that cannot be complemented, the control unit 100 determines whether or not the ejection failure level Lv is “3”. If the ejection failure level Lv is “2” (step S56: NO), the process proceeds to step S59 described later.

  On the other hand, when the ejection failure level Lv is “3” (step S56: YES), the control unit 100 adds “1” to the second counter Cnt2 (step S57), and then the second counter Cnt2 is set. It is determined whether or not the second counter determination value CntTh2 is reached (step S58). When the second counter Cnt2 is less than the second counter determination value CntTh2 (step S58: NO), the control unit 100 shifts the process to the next step S59.

  Note that the determination in step S58 is performed when the ejection failure level Lv is still “3” even when maintenance is repeatedly performed, that is, when there are many defective nozzles that do not recover ejection failure, the first counter determination value CntTh1. This is a process for suppressing execution of maintenance corresponding to the number of times. In other words, because there is a defective nozzle that does not recover from defective ejection even after repeated maintenance, ink is wasted when repeated maintenance is performed. It is a process for suppressing. For this reason, the second counter determination value CntTh2 must be less than the first counter determination value CntTh1.

  In step S59, the control unit 100 determines whether or not the first counter Cnt1 is equal to or greater than a first counter determination value CntTh1 as an example of the “specified number of times”. When the first counter Cnt1 is equal to or greater than the first counter determination value CntTh1 (step S59: YES), that is, when the discharge failure level Lv does not become “1” or less even when the maintenance is repeatedly performed, the control unit 100 notifies that a defective nozzle that cannot be complemented has occurred (step S60).

  Note that notification that a defective nozzle that cannot be complemented has occurred may be performed by, for example, displaying a message on the display unit 13. Further, when executing step S60, it may be notified that the number of maintenance executions (first counter Cnt1) has reached a specified number (first counter determination value CntTh1).

  Then, the control part 100 transfers the process to step S55. When step S59 is affirmed and step S55 is executed, since the ejection failure level Lv is “2”, complementation is performed for defective nozzles that can be complemented among the defective nozzles.

  On the other hand, when the first counter Cnt1 is less than the first counter determination value CntTh1 (step S59: NO), the control unit 100 sets the maintenance intensity (step S61). Here, the maintenance intensity is set so as to increase as the ejection failure level Lv increases. For this reason, the maintenance strength increases as the number of defective nozzles that cannot be complemented or the number of defective nozzles increases. be able to.

  Further, the maintenance intensity may be set to increase as the value of the first counter Cnt1 increases. According to this, when the maintenance is repeatedly performed, the strength of the maintenance is increased according to the number of times the maintenance is performed. For this reason, if there are defective nozzles that have failed to be recovered unless maintenance with relatively high strength is performed, maintenance with relatively low strength is repeatedly performed, so that maintenance can be performed repeatedly. It is possible to avoid a situation in which the ejection failure of the defective nozzle does not recover.

  Then, the control unit 100 performs maintenance according to the maintenance intensity (step S62), and adds “1” to the first counter Cnt1 (step S63). Thereafter, the control unit 100 shifts the process to the previous step S52.

  On the other hand, when the second counter Cnt2 is equal to or greater than the second counter determination value CntTh2 in the previous step S58 (step S58: YES), the control unit 100 complements all the nozzles 21 whose nozzle abnormality flag is on. It is determined whether or not it is possible (step S64). If it is not possible to complement all the nozzles 21 whose nozzle abnormality flag is on (step S64: NO), the control unit 100 turns on the head abnormality flag (step S65), and the process proceeds to step S60. On the other hand, when it is possible to complement all the nozzles 21 whose nozzle abnormality flag is on (step S64: YES), the control unit 100 shifts the process to step S55.

  Here, the nozzle abnormality flag is a flag that is set for each of all the nozzles 21 of all of the ejection heads 22 and is turned on when a state where ink cannot be ejected normally continues, and is otherwise turned off. To be. Further, the head abnormality flag is a flag set for the printing apparatus 11 and is turned on when there is a high possibility that printing cannot be performed normally, and is turned off otherwise. In the following description, the nozzle 21 whose nozzle abnormality flag is on is also referred to as an “abnormality nozzle”.

  In the present embodiment, even when there is an abnormality occurrence nozzle, if all the abnormality occurrence nozzles can be complemented, printing is performed after performing the complementation, thereby reducing the print quality. It is suppressed. On the other hand, if it is not possible to complement all the abnormal nozzles, the abnormal nozzles that cannot be complemented cannot eject ink to the area on the medium S where the ink should be ejected, which may reduce the print quality. high. As described above, when there is a high possibility that the print quality is deteriorated (step S64: NO), the head abnormality flag is turned on.

  The case where step S64 is negatively determined and step S60 is executed is a case where the head abnormality flag is turned on. For this reason, in this case, the control unit 100 may notify that there is an abnormality in the ejection head 22 that greatly affects the print quality when executing step S60.

  In the present processing routine, when all defective nozzles can be complemented as a result of the ejection defect level determination processing (step S54: YES), complementation is performed for all the defective nozzles, and the present processing routine is temporarily terminated. The Then, the print job is accepted (step S13), or printing based on the print job is performed (step S23). In this respect, in the present embodiment, when all defective nozzles can be complemented, printing based on the print job is permitted after the complement is performed.

  Further, when the first counter Cnt1 indicating the number of executions of maintenance reaches the first counter determination value CntTh1 (specified number) without being able to complement all the defective nozzles (step S54: NO, step S59: YES), the defective nozzle is complemented as much as possible, and this processing routine is temporarily terminated. Then, the print job is accepted (step S13), or printing based on the print job is performed (step S23). In this respect, when the number of maintenance executions reaches the specified number, the execution of printing based on the print job is permitted after performing as much complement as possible.

  In other words, according to this processing routine, when the discharge failure level Lv is equal to or lower than “1” by performing maintenance for the number of times equal to or greater than “0 (zero)” and less than the first counter determination value CntTh1. Of course, the execution of printing is permitted even if the discharge failure level Lv does not become “1” or less even if the maintenance corresponding to the first counter determination value CntTh1 is executed. Allowed.

Next, with reference to the flowchart shown in FIG. 15, the ejection failure level determination process in step S52 and in later-described S92 and S95 will be described.
As shown in FIG. 15, in the present processing routine, the control unit 100 causes the flushing to be performed (step S71) and the first nozzle check to be performed (step S72). Subsequently, the control unit 100 determines whether or not there is a defective nozzle (step S73). If there is no defective nozzle (step S73: NO), the control unit 100 sets “0 (zero)” to the ejection failure level Lv. (Step S74), this processing routine is once ended.

  On the other hand, if there is a defective nozzle (step S73: YES), the controller 100 determines whether or not it is immediately after maintenance (step S75). If it is not immediately after maintenance (step S75: NO), the process will be described later in step S79. Migrate to Whether or not it is immediately after the maintenance may be determined by counting the elapsed time from the timing when the maintenance is completed and determining whether or not the elapsed time is less than a predetermined determination time.

  On the other hand, if it is immediately after maintenance (step S75: YES), the control unit 100 extracts the nozzle 21 that is a defective nozzle before and after the latest maintenance (step S76). That is, it is included in common to the set of defective nozzles detected by the first nozzle check before execution of the latest maintenance and the set of defective nozzles detected by the first nozzle check after the execution of the latest maintenance. The nozzle 21 is extracted.

  Then, the control unit 100 adds “1” to the number of continuous failures for the nozzle 21 that is a defective nozzle before and after maintenance (step S77). Here, the number of consecutive failures is a variable set for every nozzle 21 of every ejection head 22. When there is a nozzle 21 that does not solve the discharge failure even after the maintenance is performed, the number of consecutive failures corresponding to the nozzle 21 is incremented by “1”.

  Subsequently, the control unit 100 determines whether or not the number of continuous failures exceeds the number of failure determinations for the nozzle 21 that is a defective nozzle before and after maintenance, and the nozzle 21 that has exceeded the number of failure determinations. The nozzle abnormality flag is turned on for (Step S78). That is, in step S78, the nozzle abnormality flag indicating that an abnormality has occurred is turned on for a defective nozzle whose ejection failure does not recover even when maintenance is repeatedly performed. The number of defect determinations may be set by the user, or may be determined at the design stage of the printing apparatus 11. As an example, it may be “5 times”.

  In the next step S79, the control unit 100 determines whether or not all defective nozzles detected in the previous step S72 can be complemented (step S79), and can complement all the defective nozzles. If so (step S79: YES), “1” is set to the ejection failure level Lv (step S80). Then, the control part 100 once complete | finishes this process routine.

  On the other hand, when all of the defective nozzles cannot be complemented (step S79: NO), that is, when there are one or more defective nozzles that cannot be complemented, the control unit 100 determines that the number of defective nozzles is equal to or greater than the specified number of nozzles. It is determined whether or not there is a column 27 (step S81). When there is no nozzle row 27 in which the number of defective nozzles is equal to or greater than the specified number of nozzles (step S81: NO), the control unit 100 sets “2” to the ejection failure level Lv (step S82) and executes this processing routine. Exit once. On the other hand, when there is a nozzle row 27 in which the number of defective nozzles is equal to or greater than the specified number of nozzles (step S81: YES), the control unit 100 sets “3” to the ejection failure level Lv (step S83), and this process The routine is temporarily terminated.

  Next, a processing routine executed by the control unit 100 to perform manual maintenance will be described with reference to a flowchart shown in FIG. This processing routine is a processing routine that is executed when there is a maintenance execution command from the user.

  As shown in FIG. 16, in this processing routine, the control unit 100 sets “0 (zero)” to the first counter Cnt1 and the third counter Cnt3 (step S91). The third counter Cnt3 is a counting variable that is added when the ejection failure does not recover even when the number of maintenances corresponding to the first counter determination value CntTh1 is repeatedly executed.

  Subsequently, the control unit 100 executes a discharge failure level determination process (step S92), and sets the strength of maintenance in the same manner as in step S61 (step S93). And the control part 100 performs the maintenance according to the intensity | strength of the set maintenance (step S84).

  In steps S92 to S94, when a defective nozzle is detected in the ejection failure level determination before the maintenance in step S94 (when the ejection failure level Lv is “1 to 3”), the defective nozzle is detected. Maintenance is executed both in the case where it is not detected (when the ejection failure level Lv is “0 (zero)”). Further, when all the detected defective nozzles can be complemented (when the ejection defect level Lv is “1”), and when all the detected defective nozzles cannot be complemented (the ejection defect level Lv is “2”). ”Or“ 3 ”), the maintenance is executed in both cases.

  Subsequently, the control unit 100 executes a discharge failure level determination process (step S95), and determines whether or not the discharge failure level Lv is “0 (zero)” (step S96). When the ejection failure level Lv is “0 (zero)” indicating that there is no defective nozzle (step S96: YES), the control unit 100 determines whether there is a print command for the nozzle check pattern PT (step S96). S97). Whether or not there is a print command for the nozzle check pattern PT is determined by causing the display unit 13 to display two options for whether or not to print the nozzle check pattern PT, and which option the user selects. It may be determined by In this way, in step S97, notification for prompting printing of the nozzle check pattern PT is performed.

  When there is a print command for the nozzle check pattern PT (step S97: YES), the control unit 100 causes the nozzle check pattern PT to be printed (step S98) and determines whether there is a maintenance command (step S99). On the other hand, when there is no print command for the nozzle check pattern PT (step S97: NO), the control unit 100 shifts the process to step S99. Whether or not there is a maintenance command is determined by causing the display unit 13 to display two options for whether or not to perform maintenance, as in the case of determining whether or not there is a print command for the nozzle check pattern PT. Thus, the determination may be made depending on which option the user selects. In this way, in step S99, notification for urging execution of maintenance is performed.

  If there is a maintenance command (step S99: YES), the control unit 100 shifts the process to the previous step S92. On the other hand, when there is no maintenance command (step S99: NO), the control unit 100 once ends this processing routine.

  In the previous step S96, when the ejection failure level Lv is not “0 (zero)” (step S96: NO), that is, when the ejection failure level Lv is “1” or more, the control unit 100 executes a complementing process. (Step S100). That is, of the defective nozzles detected by executing Step S95, the defective nozzles that can be complemented are complemented. The case where the negative determination is made in step S96 is a case where a defective nozzle is detected in the discharge failure level determination process in step S95.

  Then, the control unit 100 determines whether or not the ejection failure level Lv is “1” (step S101). When the ejection failure level Lv is “1” (step S101: YES), that is, all When the defective nozzle can be complemented, the control unit 100 shifts the processing to step S97. Note that when the determination in step S101 is affirmative and steps S97 and S98 are executed, the nozzle check pattern PT is notified after the defective nozzle is complemented and the nozzle check pattern PT is prompted to be printed. This is a case where PT is printed.

  On the other hand, when the ejection failure level Lv is not “1” (step S101: NO), that is, when all the defective nozzles cannot be complemented, the control unit 100 determines that the first counter Cnt1 is equal to or greater than the first counter determination value CntTh1. Whether or not (step S102). When the first counter Cnt1 is less than the first counter determination value CntTh1 (step S102: NO), the control unit 100 determines whether there is a print command for the nozzle check pattern PT (step S103).

  When there is a print command for the nozzle check pattern PT (step S103: YES), the control unit prints the nozzle check pattern PT (step S104), and determines whether there is a maintenance command (step S105). On the other hand, when there is no print command for the nozzle check pattern PT (step S103: NO), the control unit 100 shifts the process to step S105. Note that steps S103 and S104 are cases in which the nozzle check pattern PT is printed after notification that the nozzle check pattern PT is prompted to be printed after the defective nozzles that can be complemented are complemented.

  When there is no maintenance command (step S105: NO), the control unit 100 once ends this processing routine. In this case, although there are defective nozzles that cannot be complemented, it is not necessary to perform further maintenance according to the judgment of the user, and printing is to be started.

  On the other hand, when there is a maintenance command (step S105: YES), the maintenance strength is set as in step S93 (step S106). Subsequently, the control unit 100 causes the maintenance to be performed with the set maintenance intensity (step S107), and increments the first counter Cnt1 by “1” (step S108). Thereafter, the control unit 100 shifts the process to the previous step S95.

  On the other hand, in the previous step S102, when the first counter Cnt1 is equal to or greater than the first counter determination value CntTh1 (step S102: YES), the control unit 100 adds the third counter Cnt3 by “1” (step S102: YES). Step S109). Then, the control unit 100 determines whether or not the third counter Cnt3 is greater than or equal to the third counter determination value CntTh3 (step S110), and the third counter Cnt3 is less than the third counter determination value CntTh3. If so (step S110: NO), the process proceeds to step S97. On the other hand, when the third counter Cnt3 is greater than or equal to the third counter determination value CntTh3 (step S110: YES), the control unit 100 turns on the head abnormality flag (S111). Thereafter, the control unit 100 notifies a warning (S112) and once ends this processing routine.

  Note that the case where the third counter Cnt3 is equal to or greater than the third counter determination value CntTh3 means that the maintenance corresponding to the product of the first counter determination value CntTh1 and the third counter determination value CntTh3 is executed. This is a case where the ejection failure level Lv does not recover to less than “2”. Accordingly, in this case, the control unit 100 ends this processing routine without receiving a print command for the nozzle check pattern PT or a maintenance execution command. Further, in step S112, since there is a defective nozzle that does not recover the ejection defect even if the maintenance is repeatedly performed, a warning may be given that a printed matter with a desired print quality cannot be obtained even if printing is performed as it is. .

  Also, in the flowchart shown in FIG. 16, step S92 is a process that is executed before the execution of the maintenance in step S94, and is a process for detecting a discharge failure of the nozzle 21. In this respect, in the present embodiment, the first nozzle check executed inside the ejection failure level determination process in step S92 corresponds to an example of “preliminary detection”. Step S95 is a process executed after the maintenance in step S94, and is a process for detecting a discharge failure of the nozzle 21. In this respect, in the present embodiment, the first nozzle check executed inside the ejection failure level determination process in step S95 corresponds to an example of “post-detection”.

  In the flowcharts shown in FIGS. 14 and 16, the first counter determination value CntTh1, the second counter determination value CntTh2, and the third counter determination value CntTh3 place importance on improving the print quality or reduce the loss time. What is necessary is just to set suitably according to whether to attach importance. For example, in the case of automatic maintenance and manual maintenance, if it is desired to shorten the loss time even if print quality may be lowered, the counter determination values CntTh1, CntTh2, CntTh3 are used in order to reduce the number of times maintenance can be performed repeatedly. It is desirable to reduce the value. On the other hand, in the automatic maintenance and manual maintenance, when it is desired to improve the print quality even if the loss time may be long, the counter determination values CntTh1, CntTh2, and the like are used in order to increase the number of times maintenance can be performed repeatedly. It is desirable to increase CntTh3. As an example, the first counter determination value CntTh1 may be “3”, the second counter determination value CntTh2 may be “2”, and the third counter determination value CntTh3 may be “10-15”.

Next, the operation when performing automatic maintenance in the printing apparatus 11 of the present embodiment will be described. It is assumed that the automatic maintenance flag is turned on.
When a print job is input to the printing apparatus 11, automatic maintenance is executed before printing based on the print job is started. In the automatic maintenance, the first nozzle check is executed, and when the ejection failure level Lv is “0 (zero)”, printing based on the print job is started, assuming that no defective nozzle is detected. That is, in this case, printing is started without performing maintenance.

  When the ejection failure level Lv is “1”, after all the detected defective nozzles are complemented, printing based on the print job is started. That is, also in this case, printing is started without performing maintenance.

  On the other hand, when the ejection failure level Lv is “2” or “3”, the maintenance corresponding to the ejection failure level Lv is performed on the assumption that there are defective nozzles that cannot be complemented. Subsequently, the first nozzle check is executed, and when the ejection failure level Lv is “2” or “3”, the maintenance is executed again. Thus, the first nozzle check and the maintenance are repeatedly performed until the ejection failure level Lv becomes “1” or less. In the case of repeatedly performing maintenance, the strength of maintenance is gradually increased according to the number of times maintenance is performed (first counter Cnt1).

  For example, when the maintenance is repeated “3 times”, if the discharge failure level Lv is “2” in the first maintenance, weak cleaning is executed, and the discharge failure level Lv is “3”. If there is, cleaning inside is executed. Subsequently, in the second maintenance, if the ejection failure level Lv is “2”, weak cleaning is executed, and if the ejection failure level Lv is “3”, strong cleaning is executed. In the third maintenance, if the ejection failure level Lv is “2”, medium cleaning is executed, and if the ejection failure level Lv is “3”, strong cleaning is executed.

  Then, before the maintenance corresponding to the first counter determination value CntTh1 is executed, if the discharge failure level Lv is “1” or less, after all the detected defective nozzles are complemented, Printing based on the print job is started.

  In addition, even if the maintenance corresponding to the first counter determination value CntTh1 is executed, if the ejection failure level Lv is “2”, the complemented defective nozzles among the detected defective nozzles are complemented. Then, printing based on the print job is started. In addition, before the maintenance corresponding to the first counter determination value CntTh1 is performed, the number of times the ejection failure level Lv becomes “3” after the maintenance is performed is equal to or greater than the second counter determination value CntTh2. In addition, after the defective nozzles that can be complemented are detected among the detected defective nozzles, printing based on the print job is started.

  Thus, in the present embodiment, whether to perform maintenance is determined according to the ejection failure level Lv. For this reason, when the ejection failure level Lv is small, the maintenance is not performed, thereby reducing the loss time and suppressing unnecessary consumption of ink. Further, when the ejection failure level Lv is large, maintenance with strength corresponding to the ejection failure level Lv is executed. For this reason, maintenance suitable for the occurrence state of defective nozzles is executed.

  Incidentally, even if the automatic maintenance flag is turned off, the first nozzle check is performed. When a defective nozzle is detected, printing is started after the defective nozzle is complemented as much as possible. For this reason, even if the automatic maintenance flag is turned off, although maintenance is not performed, it is suppressed that the print quality is deteriorated in terms of complementation.

  When the print job is a print job for printing a plurality of media S, the first nozzle check is executed every time printing on one medium S is completed. If a defective nozzle is detected, before the printing on the next medium S is started, the defective nozzle is complemented as much as possible. For this reason, even when a plurality of media S are continuously printed, even if the occurrence state of the defective nozzle changes, the complementing mode is changed according to the change in the occurrence state. In this way, it is possible to suppress a decrease in print quality while suppressing that maintenance is interrupted and executed during printing on a plurality of media S based on a print job.

  Then, at the timing when all printing based on the print job is completed, if the number of printed sheets Pn after the most recent maintenance is performed is equal to or greater than the specified number of sheets PnTh, regular maintenance is performed. This is because when printing is performed on the medium S having the specified number of sheets PnTh or more, foreign matter (for example, paper dust) adheres to the nozzle formation surface 28 of the ejection head 22, thereby causing a decrease in print quality.

  When periodic maintenance is not executed, automatic maintenance is executed according to the state of the automatic maintenance flag. That is, the discharge failure level Lv is set based on the result of the first nozzle check, and maintenance is performed based on the discharge failure level Lv.

Next, an operation when performing manual maintenance in the printing apparatus 11 of the present embodiment will be described.
Now, in the printing apparatus 11 of the present embodiment, manual maintenance is executed when a maintenance command is issued from the user. In the manual maintenance, after determining the discharge failure level Lv, maintenance with strength corresponding to the discharge failure level Lv is executed. The maintenance is executed even when the ejection failure level Lv is “0 (zero)” indicating that there is no defective nozzle. In this way, even in the case where the true defective nozzle cannot be detected in the first nozzle check which is a premise for determining the ejection failure level Lv, the maintenance is executed.

  In this maintenance, for example, if the ejection failure level Lv is “0 (zero)”, flushing is performed, and if the ejection failure level Lv is “1”, weak cleaning is performed, and the ejection failure level Lv is If “2”, medium cleaning is executed, and if the ejection failure level Lv is “3”, strong cleaning may be executed.

  Thereafter, the ejection failure level Lv is determined, and a display for prompting printing of the nozzle check pattern PT is displayed on the display unit 13. When there is a print command, the nozzle check pattern PT is printed, and when there is no print command, the nozzle check pattern PT is not printed.

  Thereafter, the display unit 13 displays a message that prompts execution of maintenance. For this reason, when the nozzle check pattern PT is printed, the user of the printing apparatus 11 grasps the actual ink discharge state and selects whether or not to perform further maintenance.

  By the way, when the ejection failure level Lv is “0 (zero)” or “1” and there is a command to perform maintenance from the user, the ink ejection is determined from the result of the first nozzle check. Although there is no major problem in the situation, it is allowed to perform maintenance assuming that the user is not satisfied with the ink ejection situation.

  On the other hand, when the ejection failure level Lv is “2” or “3”, if there is an instruction to perform maintenance from the user, the maintenance is performed. However, when the number of maintenance times corresponding to the product of the first counter determination value CntTh1 and the third counter determination value CntTh3 is repeatedly executed, a warning that there is a non-recoverable defective nozzle is displayed on the display unit 13, Further maintenance is restricted.

  In other words, this case is a case where the discharge failure level Lv does not decrease even though the maintenance is repeatedly performed, and thus an unrecoverable discharge failure occurs due to the execution of the maintenance. Therefore, wasteful ink consumption is suppressed by performing further maintenance.

According to the embodiment described above, the following effects can be obtained.
(1) When automatic maintenance is performed, even when there are one or more defective nozzles, if the defective nozzles can be complemented, execution of printing based on the print job is permitted. Therefore, in this case, even when there is a defective nozzle, it is possible to discharge ink toward the medium S after complementing the defective nozzle without performing maintenance. On the other hand, when the number of defective nozzles is one or more and it is not possible to complement the defective nozzles, the higher the number of defective nozzles (the higher the ejection defect level Lv), the higher the maintenance is performed. For this reason, it is possible to perform maintenance with appropriate strength according to the number of defective nozzles (discharge failure level Lv). In this way, it is possible to suppress an increase in loss time during which printing cannot be performed as maintenance is performed.

  (2) During the execution of automatic maintenance, if the number of maintenance executions reaches the first counter determination value CntTh1 as an example of the prescribed number of times (first counter Cnt1), further maintenance is executed. Printing based on a print job. For this reason, it is possible to suppress an increase in ink consumption due to the repeated maintenance indefinitely due to the presence of defective nozzles that cannot be complemented.

  (3) When automatic maintenance is performed, if the number of times maintenance is performed (first counter Cnt1) reaches a first counter determination value CntTh1 as an example of the specified number of times, even if maintenance is performed It is notified that there is an impossible defective nozzle. This allows the user of the printing apparatus 11 to recognize that there are defective nozzles that cannot be complemented even though the predetermined number of times of maintenance has been performed.

  (4) When automatic maintenance is executed, if the number of maintenance executions reaches the first counter determination value CntTh1 as an example of the specified number of times (first counter Cnt1), it is possible to complement the defective nozzles. For such defective nozzles, after complementation, printing based on the print job is performed. For this reason, even when there are defective nozzles that cannot be complemented even when the maintenance corresponding to the first counter determination value CntTh1 is performed, the complementable defective nozzles can be complemented and printing can be started. For this reason, the situation where the printing apparatus 11 becomes unusable can be avoided while suppressing the deterioration of the print quality.

  (5) When a print job for printing a plurality of media S is input, a first nozzle check (detection of ejection failure between media) is executed every time printing on one medium S is completed. As a result, when a defective nozzle is detected, the defective nozzle is complemented as much as possible. According to this, the print quality can be improved as compared with the case where the first nozzle check and complement are not performed.

  (6) When manual maintenance is performed based on a maintenance command from the user, a first nozzle check (preliminary detection) is performed before the maintenance is performed to detect whether there is a defective nozzle. As a result of the first nozzle check, maintenance is performed not only when a defective nozzle is detected but also when a defective nozzle is not detected. For this reason, even if it is a case where a true defective nozzle is erroneously detected as a normal nozzle in the first nozzle check, it is possible to prevent maintenance from being executed.

  (7) When manual maintenance is performed, maintenance is performed in both cases where all defective nozzles can be complemented and cannot be complemented. For this reason, as a result of the first nozzle check, if a true defective nozzle is erroneously detected as a normal nozzle, maintenance is executed even when it is determined that all defective nozzles can be complemented. In this way, it is possible to prevent maintenance from being executed when it is determined that all defective nozzles can be complemented based on the erroneous detection result.

  (8) When manual maintenance is performed, if a defective nozzle is detected as a result of the first nozzle check (post-detection) after the maintenance is performed, a notification that prompts the formation of the nozzle check pattern PT is issued. Therefore, the user of the printing apparatus 11 can confirm the actual ink ejection state by forming the nozzle check pattern PT on the medium S according to the notification. Therefore, it is possible to make it easier for the user to determine whether or not to perform maintenance.

  (9) The nozzle check pattern PT is printed after complementing the defective nozzles that can be complemented. This makes it easier for the user to determine whether or not to perform further maintenance based on the nozzle check pattern PT printed under the same conditions as when printing based on the print job.

  (10) When the nozzle check pattern PT is printed, notification for urging execution of maintenance is performed. According to this, after the nozzle check pattern PT is formed, a notification that prompts the execution of maintenance is made, and therefore, when the user determines that the actual ink ejection state is not good after confirming the nozzle check pattern PT Can easily perform maintenance.

  (11) If the maintenance strength is made equal depending on whether or not a defective nozzle is detected, there is a possibility that maintenance with a strength suitable for the occurrence state of the defective nozzle cannot be executed. For example, there is a possibility that low-strength maintenance may be performed despite the occurrence of many defective nozzles, or high-strength maintenance may be performed despite the absence of defective nozzles. In this regard, according to the present embodiment, when a defective nozzle is not detected during the execution of manual maintenance (for example, when the ejection defect level LV is “0 (zero)”), the defective nozzle is detected. The strength of maintenance is made lower than in the case (for example, when the ejection failure level LV is “1” to “3”). For this reason, generation | occurrence | production of the said situation can be suppressed.

  (12) If the maintenance strength is made equal regardless of the number of defective nozzles, there is a possibility that maintenance with strength suitable for the occurrence state of defective nozzles cannot be performed. In this regard, according to the present embodiment, when performing maintenance during automatic maintenance and manual maintenance, when the number of defective nozzles is small (for example, when the ejection failure level Lv is “2”). The maintenance strength is set lower than when the number of defective nozzles is large (for example, when the ejection defect level Lv is “3”). For this reason, since the maintenance intensity is changed in accordance with the number of defective nozzles, the maintenance intensity can be set to an appropriate intensity for eliminating defective discharge of the defective nozzles.

  (13) By performing flushing before executing the first nozzle check, the conditions for executing the first nozzle check are leveled regardless of the ink ejection status before the first nozzle check is executed. can do. For this reason, the accuracy of the first nozzle check can be increased.

In addition, you may change the said embodiment as shown below.
-Automatic maintenance may be performed in the return process. Here, the return process is, for example, a process for returning to a printable state when the medium S is jammed in the transport path of the medium S due to an increase in the load of the transport unit 96 (transport motor). .

  As shown in FIG. 17, the control unit 100 determines whether or not an abnormality has occurred in each component such as the transport unit 96 (step S121). Whether or not an abnormality has occurred in the transport unit 96 may be determined based on, for example, whether or not the magnitude of the load when the transport unit 96 (transport motor) is driven is less than a predetermined value.

  If no abnormality has occurred in each configuration (step S121: NO), the control unit 100 executes automatic maintenance processing (step S122), and once ends this processing routine. On the other hand, if an abnormality has occurred in each component (step S121: NO), the control unit 100 displays a message that restricts execution of printing based on the print job or prompts the user to solve the problem. 13 is executed (step S123), and this processing routine is temporarily terminated.

According to this, since the automatic maintenance is performed in the return process, the effect of the above embodiment can be obtained.
In the automatic maintenance process shown in FIG. 14, the maintenance may be repeatedly performed until the ejection failure level Lv becomes “1” or less. A processing routine executed by the control unit 100 in this case will be described with reference to a flowchart shown in FIG.

  As shown in FIG. 18, in the present processing routine, the control unit 100 executes a discharge failure level determination process (step S131). Then, the control unit 100 determines whether or not the ejection failure level Lv is “0 (zero)” (step S132). When the ejection failure level Lv is “0 (zero)” (step S132: YES) ), This processing routine is temporarily terminated. On the other hand, when the discharge failure level Lv is not “0 (zero)” (step S132: NO), the control unit 100 determines whether or not the discharge failure level Lv is “1” (step S133). When the level Lv is “1” (step S133: YES), a complementing process is executed (step S134), and this processing routine is temporarily ended. On the other hand, when the ejection failure level Lv is “2” or “3” (step S133: NO), the control unit 100 sets the maintenance intensity in the same manner as in step S61 (step S135), and executes maintenance (step S135). Step S136). Thereafter, the control unit 100 shifts the process to step S131.

  Thus, according to this processing routine, the maintenance is repeatedly performed until the ejection failure level Lv becomes “0 (zero)” or “1”, that is, until all defective nozzles can be complemented. . For this reason, although the consumption of ink tends to increase due to repeated maintenance, printing is not performed when the ejection failure level Lv is “2” or “3”, so that the print quality can be improved. it can. That is, the ink landing accuracy on the medium S can be increased.

  For example, in step S32 of the flowchart shown in FIG. 12, if the nozzle row 27 to be subjected to the first nozzle check is all the nozzle rows 27, the time required for the first nozzle check becomes longer. There is a possibility that a loss time during which printing cannot be executed after printing on the medium S is finished until printing on the next medium S is started may occur.

  Therefore, in step S32 of the flowchart shown in FIG. 12, the first nozzle check target may be one nozzle row 27 (for example, the nozzle row 27 that ejects black ink). In this case, it is desirable to change the nozzle row 27 to be subjected to the first nozzle check every time the printing process is executed.

  Specifically, after the printing of the j-th medium S among the plurality of mediums S to be printed based on the print job, the processes of steps S32 and S33 are executed for the nozzle row 27k that ejects black ink. After printing of the (j + 1) th medium S, the processes of steps S32 and S33 may be executed for the nozzle row 27c that discharges cyan ink. Further, after the printing of the j + 2th medium S is completed, the processes of steps S32 and S33 are executed for the nozzle row 27m that ejects magenta ink, and the yellow ink is ejected after the printing of the j + 3th medium S is completed. The processing of steps S32 and S33 may be executed for the nozzle row 27y to be performed.

  According to this, since all the nozzle rows 27 are not subjected to inspection in one first nozzle check, the time required for one first nozzle check can be shortened. On the other hand, since the nozzle row 27 to be inspected is changed for each first nozzle check, it is possible to suppress the occurrence of the nozzle row 27 in which the ejection failure of the nozzle 21 is not detected over a long period of time. Can do. Note that the nozzle row 27 to be inspected in one first nozzle check may be the nozzle row 27 for two rows or the nozzle row 27 for three rows.

  Executed when a print job for performing normal printing is input and when a print job for performing FAX printing is input in a processing routine executed when printing based on a print job is started The processing to be performed may be changed. Next, a processing routine executed by the control unit 100 in this case will be described with reference to a flowchart shown in FIG.

  As shown in FIG. 19, the control unit 100 determines whether or not the head abnormality flag is on (step S141). If the head abnormality flag is on (step S141: YES), the input print job is FAX. It is determined whether the print job is for printing (step S142). When the input print job is a print job for performing FAX printing (step S142: YES), the control unit 100 stores the FAX data in the storage unit 101 (step S143). Thereafter, the control unit 100 notifies that the FAX printing has been stopped (step S144), and once ends this processing routine. Note that the notification that the FAX printing is stopped may be performed via the display unit 13.

  On the other hand, when the input print job is not a print job for performing FAX printing (step S142: NO), the control unit 100 notifies the user that the print quality is deteriorated (step S145), and the user issues a print command. It is determined whether or not there is (step S146). When there is no print command from the user (step S146: NO), that is, when there is a print interruption command from the user, the control unit 100 interrupts printing based on the print job (step S147), and temporarily executes this processing routine. finish. When the printing based on the print job is interrupted, the control unit 100 may or may not store the print data in the storage unit 101.

  On the other hand, when there is a print command from the user (step S146: YES), the control unit 100 causes the flushing to be performed (step S148), and the first nozzle check is performed (step S149). Thereafter, the control unit 100 executes a complementing process (step S150), and performs printing based on the print job (step S151). When printing ends, the control unit 100 once ends this processing routine.

  In the previous step S141, if the head abnormality flag is off (step S141: NO), the control unit 100 determines whether or not the automatic maintenance flag is on (step S152), and if the automatic maintenance flag is off (step S152). (S152: NO), the process proceeds to step S148. On the other hand, when the automatic maintenance flag is on (step S152: YES), the control unit 100 executes an automatic maintenance process (step S153), and the process proceeds to step S151.

  According to this, when the head abnormality flag is ON, printing based on a print job for performing FAX printing is restricted, and FAX data is stored in the storage unit 101. For this reason, by performing printing based on the print job, it is possible to prevent the printing quality of FAX printing from being deteriorated. Further, since FAX data is normally discarded after the FAX printing is completed, it is possible to suppress loss of FAX data by performing FAX printing in which the print quality is poor and the contents cannot be grasped. it can.

  The maintenance strength may be set based only on the ejection failure level Lv. In this case, the maintenance intensity may be set to increase stepwise as the ejection failure level Lv increases, or may be set to be proportional to the ejection failure level Lv.

  The maintenance strength may be set based only on the first counter Cnt1 indicating the number of times maintenance is performed. In this case, the maintenance intensity may be set to increase stepwise as the first counter Cnt1 increases, or may be set to be proportional to the first counter Cnt1.

  -It is not necessary to set the discharge failure level Lv. In a situation where the ejection failure level Lv is not set, it is desirable that the maintenance intensity be lower when a defective nozzle is not generated than when a defective nozzle is generated. Further, in a situation where defective nozzles are generated, it is desirable that the maintenance strength be lower when all defective nozzles can be complemented than when all defective nozzles are not supplementable. In a situation where defective nozzles are generated, when the number of defective nozzles is small, it is desirable to lower the maintenance strength than when the number of defective nozzles is large.

  In the printing apparatus 11 of the above-described embodiment, the maintenance performed to eliminate defective ejection of defective nozzles includes the following maintenance. That is, “flushing” in which ink is ejected from the nozzles 21 regardless of printing by driving the actuator 43, and “pressure wiping” (in which the wiping is performed in a state where the ink is bulged from the nozzles 21 by driving the pressure increasing mechanism 62). 5 ”) and“ suction cleaning ”described above.

  If the maintenance is arranged in the order of low discharge failure recovery capability, that is, in the order of low maintenance intensity, flushing, pressure cleaning, and suction cleaning are performed. Therefore, the maintenance strength may be set by selecting one cleaning from the above-mentioned cleanings.

  Here, when pressure wiping is selected as the maintenance, it is possible to recover the defective ejection of the defective nozzle while suppressing the ink consumption accompanying the execution of the maintenance. In this case, in addition to the maintenance device 26, the ejection head 22 corresponds to an example of a “maintenance unit”.

  As the lowest strength maintenance, the actuator 43 is driven to apply a lower voltage to the piezoelectric element 44 at a predetermined interval than when liquid is discharged, and the vibrating wall 45 is vibrated to such an extent that ink is not discharged from the nozzle 21. “Fine vibration” may be executed.

In the manual maintenance process, the maintenance intensity may be constant.
In the manual maintenance process, the steps related to printing the nozzle check pattern PT may be omitted.

  A restriction valve capable of restricting the flow of ink may be provided in the liquid outlet path 34 between the common liquid chamber 41 and the pressure chamber 52. In this case, when suction cleaning is performed, the negative pressure may be applied to the liquid lead-out path 34 abruptly by opening the restriction valve after applying the negative pressure to the closed space with the restriction valve closed. According to this, compared with the case where the suction cleaning which does not open / close the control valve is executed, maintenance with high strength can be executed.

  In the flowchart shown in FIG. 12, the complementing process based on the result of the first nozzle check after printing on the j-th medium S may not be performed before the printing on the j + 1-th medium S is started. For example, the complementing process based on the result of the first nozzle check after printing on the jth medium S may be executed before starting printing on the j + 2th and subsequent mediums S.

  -Before step S51 of FIG. 14 and step S91 of FIG. 16, the control part 100 may determine whether a head abnormality flag is ON. When the head abnormality flag is on, the control unit 100 may display on the display unit 13 that there is a defective nozzle that cannot be recovered, and once terminate this processing routine. According to this, when there is a defective nozzle that cannot be recovered even if maintenance is performed, it is possible to avoid a situation in which ink is consumed unnecessarily by performing automatic maintenance and manual maintenance.

  If the length of the medium S in the width direction X is clear based on the contents of the print job, the nozzles 21 that do not eject ink when printing on the medium S are not subject to the first nozzle check. It may be excluded.

The complement processing may be performed by performing at least one of the above-described neighborhood complement, alternative complement, and mixed color complement.
As shown in FIG. 8, in the above embodiment, when the i-th nozzle 21 (i) is a defective nozzle, the i-2th nozzle 21 (i-2), i-th Although the ink discharge amounts of the first nozzle 21 (i−1), the (i + 1) th nozzle 21 (i + 1), and the (i + 2) th nozzle 21 (i + 2) are changed, it is not necessary to do so.

  For example, in the proximity complement, the nozzles that change the ink ejection amount may be only the (i−1) th nozzle 21 (i−1) and the (i + 1) th nozzle 21 (i + 1). In the proximity complement, the nozzles that change the ink discharge amount are the i-3th nozzle 21 (i-3) to the i-1th nozzle 21 (i-1) and the i + 1th nozzle 21 (i + 1). To the (i + 3) th nozzle 21 (i + 3).

  In the second nozzle check, the determination subject of the nozzle check pattern PT may not be the user of the printing apparatus 11. For example, a control unit that controls the image reading device 12 may be used.

  The printing apparatus 11 may be connected to a management server that transmits and receives various types of information of the printing apparatus 11 via a network. In this case, the management server transmits a maintenance instruction, a maintenance prohibition instruction, a print prohibition instruction, a power forced off instruction, and the like to the printing apparatus 11 based on the result of the first nozzle check of the printing apparatus 11. May be. In addition, when the head abnormality flag is turned on in the printing apparatus 11, the management server may perform a repair arrangement by a service person or a notification to that effect. Further, the printing apparatus 11 in this case may be a printing apparatus having a smart charge (registered trademark) function in which a usage fee is determined according to the number of printed sheets Pn.

  -When the temperature in the usage environment of the printing apparatus 11 is low, the viscosity of the ink tends to be higher than when the temperature is high. For this reason, depending on the use environment of the printing apparatus 11, the vibration mode of the residual vibration of the vibration wall 45 may change, which may reduce the accuracy of the first nozzle check. Therefore, the printing apparatus 11 may include a temperature detection unit that detects the temperature of the ink in the ejection head 22 and a temperature adjustment unit that adjusts the temperature of the ink in the ejection head 22.

  Then, the drive of the temperature adjustment unit may be controlled so that the temperature of the ink in the ejection head 22 detected by the temperature detection unit falls within a temperature range suitable for the first nozzle check. Note that the waveform of the residual vibration detected may be corrected based on the temperature of the ink in the ejection head 22 detected by the temperature detection unit without providing the temperature adjustment unit.

  A circulation channel that circulates ink between the liquid supply source 23 and the pressure adjustment mechanism 25 and a circulation pump that circulates ink in the circulation channel may be provided. In this case, the first nozzle check may be performed while the ink is circulated through the circulation channel. According to this, the first nozzle check can be efficiently performed during the circulation of ink as an example of the loss time. When maintenance is to be executed as a result of the first nozzle check, the circulation pump is driven strongly, and the valve body 54 is moved to the open position by the pressure increasing mechanism, so that the nozzles of the discharge head 22 The ink may be discharged from 21.

  The first nozzle check may not be performed according to the output signal of the actuator 43 corresponding to the residual vibration of the vibration wall 45. For example, it may be determined whether or not a discharge failure has occurred in the nozzle 21 by optically detecting the size, shape, flight path, and flight speed of the ink droplets ejected from the nozzle 21. Alternatively, ink droplets may be ejected from the nozzle 21 toward the detection electrode, and it may be determined whether or not ejection failure has occurred in the nozzle 21 based on an electrical change occurring in the electrode. As described above, the first nozzle check may be performed only by the printing apparatus 11 without the user's judgment.

  In addition, when the first nozzle check is not performed according to the output signal of the actuator 43, the actuator 43 may not include the piezoelectric element 44. For example, a device equipped with an electrostatic drive element or a device equipped with a heater element that discharges droplets from the nozzle 21 using the pressure (expansion pressure) of bubbles generated by film boiling by heating ink is employed. Also good.

  When the voltage applied to the actuator 43 is large, defective nozzles can be detected with higher accuracy than when the voltage is small, and ink may be ejected from the nozzles 21. Therefore, in the first nozzle check (steps S44 and S52) executed during the automatic maintenance process after the completion of printing based on the print job, the first nozzle check (step S32) executed during printing based on the print job. ), The voltage applied to the actuator 43 may be increased.

  According to this, since the ink is not ejected from the nozzles 21 in the first nozzle check during printing on the plurality of media S based on the print job, the possibility of contamination of the media S with ink is reduced. Can do. Further, in the first nozzle check after the printing on the plurality of media S based on the print job, it is possible to detect the defective nozzle with high accuracy. Therefore, after complementing the defective nozzle, the first nozzle check is performed based on the next print job. Printing can be started. In the first nozzle check after the printing is finished, in order to prevent ink from adhering to the support base that supports the medium S, a position where the cap or the flushing box faces the ejection head 22 (line head 31). It is desirable to move to.

  The line head 31 may have only one ejection head 22 having a length corresponding to the length of the medium S in the width direction X. In this case, proximity complement and color mixture complement are performed in the complement processing.

In the ejection head 22 constituting the line head 31, the nozzle row 27 may be formed in a direction that intersects the width direction X.
The printing apparatus 11 includes a carriage that holds the ejection head 22, and performs printing by ejecting ink from the ejection head 22 toward the medium S while reciprocating the carriage in the width direction X. An inkjet printer may be used. In this case, it is desirable to change the interpolation method for the defective nozzle and the nozzle check pattern PT to those suitable for a serial type ink jet printer.

The medium S is not limited to paper, but may be a plastic film or a thin plate, or may be a cloth, a clothing such as a T-shirt, or a three-dimensional object such as a stationery or tableware.
The liquid ejected by the ejection head 22 of the liquid ejection apparatus is not limited to ink, but may be, for example, a liquid material in which functional material particles are dispersed or mixed in the liquid. For example, recording is performed by ejecting a liquid material in which a material such as an electrode material or a color material (pixel material) used for manufacturing a liquid crystal display, an EL (electroluminescence) display, and a surface emitting display is dispersed or dissolved. It may be configured.

  DESCRIPTION OF SYMBOLS 10 ... Multifunction machine, 11 ... Printing apparatus (an example of a liquid discharge apparatus), 12 ... Image reading apparatus, 13 ... Display part, 14 ... Feed cassette, 15 ... 1st discharge tray, 16 ... Feed tray, 17 ... Second discharge tray, 21 (21c, 21m, 21y, 21k) ... nozzle, 22 ... discharge head, 221 ... first discharge head, 222 ... second discharge head, 223 ... third discharge head, 224 ... Fourth discharge head, 23 ... liquid supply source, 24 ... supply mechanism, 25 ... pressure adjustment mechanism, 26 ... maintenance device (an example of a maintenance unit), 27 (27c, 27m, 27y, 27k) ... nozzle row, 28 ... Nozzle forming surface, 31 ... line head, 32 ... liquid supply path, 33 ... storage container, 34 ... liquid outlet path, 35 ... gas delivery path, 36 ... pressurization valve, 37 ... pressurization pump, 41 ... common liquid chamber, 42 ... Cavite , 43 ... Actuator, 44 ... Piezoelectric element, 45 ... Vibration wall, 51 ... Movable wall, 52 ... Pressure chamber, 53 ... Supply chamber, 54 ... Valve body, 541 ... Seal part, 55 ... First biasing member, 55 ... Biasing member 56 ... Biasing member 56 ... Second biasing member 57 ... Inlet hole 58 ... Outlet hole 59 ... Pressure receiving plate 61 ... Differential pressure valve mechanism 62 ... Pressure increasing mechanism 81 ... Cap 82 DESCRIPTION OF SYMBOLS ... Suction mechanism, 83 ... Wiping unit, 84 ... Suction tube, 85 ... Waste liquid storage part, 86 ... Pressure reducing pump, 87 ... Pressure reducing valve, 88 ... Wiping part, 89 ... Holding part, 91 ... Guide shaft, 92 ... Drive part, 95 ... detection unit, 96 ... conveying unit, 97 ... FAX communication unit, 100 ... control unit, 101 ... storage unit, S ... medium, Cnt1 ... first counter, Cnt2 ... second counter, Cnt3 ... third counter , CntTh1... First counter Determination value, CntTh2: second counter determination value, CntTh3: third counter determination value, Id: ink droplet, Lv: ejection failure level, M: meniscus, Pn: number of printed sheets, PnTh: specified number of sheets, PT (PTc, PTm, PTy, PTk) ... nozzle check pattern, F ... transport direction, X ... width direction.

Claims (7)

An ejection head having a plurality of nozzles capable of ejecting liquid toward the medium;
A maintenance unit for performing maintenance of the discharge head;
A controller that causes the ejection head to eject the liquid onto the medium based on a liquid ejection command;
A discharge failure detection unit for detecting discharge failure of the nozzle,
When the nozzle in which the ejection failure is detected is a defective nozzle, and the nozzle in which the ejection failure is not detected is a normal nozzle,
The control unit, when the defective nozzle is detected,
It is determined for each defective nozzle whether or not the liquid discharge from the defective nozzle can be complemented by the liquid discharge from the normal nozzle,
When the complement is possible for all the defective nozzles, the liquid discharge based on the ejection command is permitted after the complement is performed, and when the complement is not possible for all the defective nozzles, the defective nozzle The liquid discharge apparatus is characterized in that the maintenance is performed with a higher strength as the number of the liquids increases. When the complement is not possible for all the defective nozzles, the control unit performs the maintenance until the complement is possible for all the defective nozzles, and then performs the complement for all the defective nozzles. The liquid ejection apparatus according to claim 1, further comprising: permitting liquid ejection based on the ejection command. The liquid ejecting apparatus according to claim 2, wherein when the number of executions of the maintenance reaches a predetermined number of times set in advance, the control unit permits ejection of liquid based on the ejection command. The liquid ejecting apparatus according to claim 3, wherein when the number of executions of the maintenance reaches the specified number of times, the control unit notifies that fact. When the number of executions of the maintenance reaches the specified number of times, the control unit supplements the defective nozzles that can be complemented among the defective nozzles, and then discharges the liquid based on the ejection command. The liquid ejection device according to claim 3 or 4, wherein the liquid ejection device according to claim 3 or 4 is permitted. The controller is
When there is an ejection command for ejecting the liquid to a plurality of the media, the ejection failure detection unit reports the ejection failure of the nozzle every time the ejection of the liquid to one or more of the media is completed. Execute the inter-medium ejection failure detection to be detected,
The said complement is performed about the said defective nozzle which can be complemented among the said defective nozzles, when the said defective nozzle is detected in the said between-medium discharge defect detection. The liquid discharge apparatus as described in any one of them. The ejection head has a plurality of nozzle groups composed of a plurality of the nozzles,
The controller is
In one-time discharge failure detection between the media, a part of the plurality of nozzle groups is set as a detection target of a liquid discharge failure,
The liquid ejecting apparatus according to claim 6, wherein each time the inter-medium ejection failure detection is executed, a part of the nozzle group to be detected as a liquid ejection failure is changed.

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