JP2011201155A - Control method for liquid ejection device and liquid ejection device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a control method for a liquid ejection device in which a trouble with the liquid droplet ejection operation can be solved by operating an operation means for starting cleaning while suppressing useless consumption of liquid droplets ejected from nozzles and a medium such as a recording paper.SOLUTION: The liquid ejection device determines whether or not dot omission occurs when the operation means for starting cleaning of a liquid ejection head is operated, and determines whether or not the operation means is operated before a predetermined time passes from the end of the liquid droplet ejection operation last time if dot omission does not occur. In the case where dot omission occurs, and in the case where the operation means is operated before the predetermined time passes although dot omission does not occur, normal cleaning of ejecting a predetermined amount of liquid droplets from the nozzles is carried out. In the case where dot omission does not occur and the operation means is operated after the predetermined time passes, pseudo-cleaning of reducing liquid droplets to be ejected from the nozzles from in normal cleaning is carried out.

Description

  The present invention relates to a method for controlling a liquid ejection apparatus having a liquid ejection head in which a plurality of nozzles for ejecting droplets are arranged, and a liquid ejection apparatus.

  The ink jet printer includes a print head having a plurality of nozzles that eject ink droplets, and the print head is mounted on a carriage such that a nozzle forming surface on which the plurality of nozzles are arranged faces downward. Also, some inkjet printers have a manual cleaning button for starting the print head cleaning by manual operation. In this inkjet printer, when the manual cleaning button is pressed, a fixed amount is output from each nozzle. A flushing operation for discharging the ink droplets, an ink suction operation for sucking ink from the nozzles, a wiping operation for wiping the nozzle forming surface, and the like are performed.

  The manual cleaning button is originally to be pressed when cleaning is necessary due to a color defect due to color mixing of inks, a deviation in the landing position of ink droplets, and / or a printing defect such as missing dots. However, in practice, for example, when an inkjet printer is started up every morning, an unfamiliar operator may conventionally perform cleaning by pressing a manual cleaning button, even though cleaning is unnecessary. In this case, since a predetermined amount of ink is ejected even though cleaning is not required, the ink is wasted.

  Therefore, a printing head cleaning method capable of suppressing wasteful consumption of ink has been proposed by the present applicant (see, for example, Patent Document 1). In the cleaning method described in Patent Document 1, when the manual cleaning button is pressed before a predetermined time has elapsed since the end of the previous printing process, normal cleaning is performed in which suction is performed while discharging a predetermined amount of ink from the nozzle. When a manual cleaning button is pressed after a predetermined time has elapsed since the end of the previous printing process, pseudo cleaning is performed in which the amount of ink liquid ejected from the nozzles is reduced compared to normal cleaning.

  That is, in this cleaning method, when the manual cleaning button is pressed before the predetermined time has elapsed since the end of the previous printing process, the operator performs nozzle check pattern printing to confirm that there is actually a printing defect. After that, it is assumed that the manual cleaning button has been pressed and normal cleaning is performed.When the manual cleaning button is pressed after a predetermined time has elapsed since the end of the previous printing process, there is actually a printing defect. The pseudo cleaning is carried out by assuming that the manual cleaning button has been pressed without the operator confirming whether or not there is any. According to this cleaning method, for example, even if the manual cleaning button is pressed at the start-up of the inkjet printer every morning, the pseudo cleaning is performed, so that wasteful ink consumption can be suppressed.

  Conventionally, there is known an ink jet printer including an ink droplet discharge inspection device that inspects whether or not dot missing has occurred (that is, whether or not there is a nozzle that is clogged) (for example, a patent) Reference 2). In the ink jet printer described in Patent Document 2, whether or not dot missing has occurred based on a change in current when the charged ink discharged from the nozzle lands on the absorbent in the head cap facing the print head. Inspection has been conducted.

JP 2007-50525 A JP 2009-190282 A

  In the cleaning method described in Patent Document 1, pseudo cleaning is performed when a manual cleaning button is pressed after a predetermined time has elapsed since the end of the previous printing process. For this reason, when printing is performed after a predetermined time has elapsed since the end of the previous printing process, and there is a situation in the print head that causes printing problems such as missing dots, press the manual cleaning button. In some cases, however, the print head cannot be cleaned so as not to cause a printing defect. In this case, if the manual cleaning button is pressed after the printing process such as nozzle check pattern printing is performed, the normal cleaning is performed. Therefore, the print head can be cleaned so as not to cause a printing failure. When printing processing such as nozzle check pattern printing is performed, recording paper is wasted.

  Accordingly, an object of the present invention is to operate an operation means for starting cleaning manually while suppressing wasteful consumption of droplets discharged from the nozzles and wasteful consumption of a medium such as recording paper. Another object of the present invention is to propose a method for controlling a liquid ejection device and a liquid ejection device capable of eliminating the problem of the droplet ejection operation.

  In order to solve the above-described problem, the control method of the liquid discharge apparatus according to the present invention is such that when an operation means for starting the cleaning of a liquid discharge head having a plurality of droplet discharge nozzles by a manual operation is operated. In the dot missing determination step for determining whether or not the dot missing has occurred by inspecting whether or not the dot missing in which the nozzle that does not discharge the droplet exists is present, An elapsed time determining step for determining whether or not the operating means has been operated before a predetermined time has elapsed since the end of the previous droplet discharge operation when it is determined that the missing dot has not occurred; When it is determined in the dot missing determining step that the dot missing has occurred, and before the predetermined time has elapsed in the elapsed time determining step, When it is determined that the operating means has been operated, the normal cleaning step for performing normal cleaning for discharging a predetermined amount of liquid droplets from the nozzle, and the elapsed time determining step, the operating means A pseudo-cleaning step for performing pseudo-cleaning in which droplets discharged from the nozzles are reduced rather than the normal cleaning when it is determined that the operation has been performed.

  In the method for controlling a liquid ejection apparatus according to the present invention, when it is determined that a missing dot has occurred in the missing dot determination step when an operation means for starting the cleaning of the liquid ejection head by a manual operation is operated. The normal cleaning for discharging a predetermined amount of droplets from the nozzle is performed. For this reason, even when a predetermined time has elapsed from the end of the previous droplet discharge operation until the operation means is operated, it is possible to eliminate missing dots without consuming a medium such as recording paper. It becomes possible.

  Further, in the present invention, even if it is determined in the missing dot determining step that no missing dot has occurred, it is determined in the elapsed time determining step that the operating means has been operated before the predetermined time has elapsed. Normal cleaning is performed. In this case, missing dots have not occurred, but the operator has performed nozzle check pattern printing, etc., and after confirming that there is actually a malfunction in the droplet ejection operation, such as deviation in the landing position of the droplet Since it is presumed that the operation means has been operated, it is possible to eliminate the problem of the droplet discharge operation by performing normal cleaning.

  Further, in the present invention, when it is determined that no dot dropout has occurred in the dot dropout determination step, and when it is determined that the operation means has been operated after a predetermined time has passed in the elapsed time determination step In this case, pseudo cleaning is performed in which the number of droplets discharged from the nozzles is reduced as compared with normal cleaning. In this case, it is presumed that the operator has operated the operating means without confirming that the missing dot has not occurred and that there is actually a problem such as a deviation in the landing position of the droplet, and cleaning is not performed. Since it is estimated that it is unnecessary, it is possible to suppress wasteful consumption of droplets ejected from the nozzles by performing pseudo cleaning.

  In the present invention, for example, the liquid ejection head is an inkjet head having a plurality of nozzles for ejecting ink droplets, and in the elapsed time determination step, before the predetermined time elapses from the end of the previous printing, It is determined whether or not the operating means has been operated. In this case, in the liquid ejecting apparatus having the ink jet head, the operation means for starting the cleaning manually is operated while suppressing the wasteful consumption of the ink droplets ejected from the nozzle and the wasteful consumption of the recording paper. By doing so, it is possible to eliminate printing defects.

  In order to solve the above problems, a liquid discharge apparatus according to the present invention includes a liquid discharge head having a plurality of nozzles for discharging liquid droplets, a cleaning mechanism for cleaning the liquid discharge head, and the cleaning mechanism by manual operation. An operation means for starting the cleaning and starting the cleaning, and when the operation means is operated, whether or not there is a missing dot in which there are nozzles that do not discharge droplets among the plurality of nozzles A droplet discharge inspection mechanism for inspecting the liquid, a time measuring means for measuring an elapsed time from the end of the previous droplet discharge operation until the operation means is operated, and the dot by the inspection by the droplet discharge inspection mechanism When missing is detected, and when the missing dot is not detected but the elapsed time measured by the timing means is within a predetermined time, The cleaning mechanism is controlled so as to perform normal cleaning for discharging a predetermined amount of droplets from the nozzle, and the dot missing is not detected by the inspection by the droplet discharge inspection mechanism and is measured by the time measuring means. A cleaning mechanism control means for controlling the cleaning mechanism so as to perform pseudo cleaning in which droplets discharged from the nozzles are reduced rather than the normal cleaning when the elapsed time exceeds the predetermined time; Features.

  In the liquid ejection apparatus of the present invention, the cleaning mechanism control means is configured to perform normal cleaning when a missing dot is detected by an inspection by the droplet ejection inspection mechanism that is executed when the operation means is operated. Is controlling. Therefore, even when a predetermined time has elapsed since the end of the previous droplet discharge operation, it is possible to eliminate missing dots without consuming a medium such as recording paper. In the present invention, the cleaning mechanism control means performs normal cleaning when no missing dot is detected but the elapsed time from the end of the previous droplet discharge operation to the operation means being within a predetermined time. The cleaning mechanism is controlled to perform. In this case, missing dots have not occurred, but the operator has performed nozzle check pattern printing, etc., and after confirming that there is actually a malfunction in the droplet ejection operation, such as deviation in the landing position of the droplet Since it is presumed that the manual cleaning button has been pressed, it is possible to solve the problem of the droplet discharge operation by performing normal cleaning. Further, in the present invention, the cleaning mechanism control unit detects the pseudo-cleaning when the dot missing is not detected and the elapsed time from the end of the previous droplet discharge operation until the operation unit is operated exceeds a predetermined time. The cleaning mechanism is controlled to perform. In this case, it is presumed that the manual cleaning button was pressed without the operator confirming that there was no defect such as a drop in the landing position of the liquid droplets, and that there was no defect. Therefore, it is possible to suppress wasteful consumption of liquid droplets ejected from the nozzles by performing pseudo cleaning.

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

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

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

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

  A power switch 7a, a paper feed switch 7b, a plurality of operation state display lamps 7c, and the like are arranged on the right side of the opening / closing lid 5 on the front surface of the printer case 2. In this portion, an operation switch 7d is disposed as an operation means for starting cleaning of the inkjet head 14 described later by manual operation. A mounting port 8 a of an ink cartridge mounting portion 8 having a vertically long rectangular cross section extending in the front-rear direction of the printer is opened on the left side portion of the opening / closing lid 5 on the front surface of the printer case 2, and the ink cartridge 9 is provided in the ink cartridge mounting portion 8. Is installed. When a button (not shown) is operated, the lock is released, the ink cartridge 9 is pushed forward by the spring force, and the ink cartridge 9 can be pulled out.

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

  The control unit 36 is connected to a cleaning mechanism 39 that performs cleaning for eliminating printing defects such as missing dots. The cleaning mechanism 39 includes a mechanism for performing a flushing operation of the ink pumps 16a to 16d, a mechanism for performing an ink suction operation such as a tube pump and a motor for driving the tube pump, and a wiping mechanism for performing a wiping operation. 26. A cleaning mechanism drive circuit 40 that drives a cleaning mechanism 39 is connected to the head maintenance unit controller 37. An operation switch 7 d is connected to the head maintenance unit control unit 37, and a predetermined signal is input to the head maintenance unit control unit 37 when the operation switch 7 d is pressed.

  The head maintenance unit controller 37 is connected to a timer 41 as a time measuring means for measuring the elapsed time from the end of the previous printing operation (at the end of the droplet discharge operation) until the operation switch 7d is pressed. . The timer 41 starts measuring the elapsed time when the printing operation by the inkjet head 14 is completed, and ends measuring the elapsed time when the operation switch 7d is pressed. The printing by the inkjet head 14 includes nozzle check pattern printing for the operator to check the printing state on the recording paper in addition to normal printing on the recording paper.

(Cleaning control during operation switch operation)
FIG. 8 is a flowchart showing the flow of cleaning control when the operation switch 7d is pressed. In the inkjet printer 1, when the operation switch 7d is pressed, an ink droplet ejection inspection is performed. In addition, after the ink droplet ejection inspection is performed, normal cleaning or pseudo cleaning is performed under predetermined conditions. In the normal cleaning of this embodiment, a flushing operation for ejecting a predetermined amount of ink droplets from the ink nozzle, an ink suction operation for sucking ink from the ink nozzle, and a wiping operation for wiping the nozzle surface 14a with the head wiper 25 are performed. Then, an operation of ejecting a very small amount of ink droplets smaller than the ejection amount in the normal cleaning from the ink nozzle is performed. Hereinafter, the flow of the cleaning control when the operation switch 7d is pressed will be described with reference to FIG.

  When the operation switch 7d is pressed by the operator, the control unit 36 discharges charged ink droplets from the ink nozzles of the inkjet head 14 at the home position 15A, and performs an ink droplet discharge test (step S1). The maintenance unit control unit 37 determines whether dot missing has occurred (step S2).

  If it is determined in step S2 that dot missing has occurred, the head maintenance unit control unit 37 controls the cleaning mechanism 39 via the cleaning mechanism drive circuit 40 in order to eliminate the dot missing. Normal cleaning is performed (step S3). That is, the cleaning mechanism 39 performs a flushing operation, an ink suction operation, and a wiping operation. When normal cleaning is performed, the cleaning control ends.

  On the other hand, if it is determined in step S2 that no missing dot has occurred, the head maintenance unit controller 37 determines whether or not the previous printing was performed within a predetermined time before the operation switch 7d was pressed. Is determined (step S4). That is, in step S4, the head maintenance unit control unit 37 determines whether or not the operation switch 7d has been pressed before a predetermined time has elapsed since the end of the previous printing operation. Specifically, in step S4, the head maintenance unit control unit 37 determines whether or not the time measured by the timer 41 exceeds a predetermined time.

  If it is determined in step S4 that the operation switch 7d has been pressed before the predetermined time has elapsed since the end of the previous printing operation, dot missing has not occurred, but the operator performs nozzle check pattern printing on the recording paper. Or after performing normal printing on a recording sheet and confirming that there is actually a printing defect such as a color defect due to color mixing of ink or a landing position deviation of ink droplets, and the like. It is estimated that was pressed. Therefore, in this case, in order to eliminate problems such as deviation of the landing positions of ink droplets, the process proceeds to step S3 and normal cleaning is performed. Here, the predetermined time in step S4 may be a sufficient time until the operator confirms the printing state of the recording paper and presses the operation switch 7d after the end of the previous printing operation, for example, 1 hour. 30 minutes or 2 hours.

  If it is determined in step S4 that the operation switch 7d has been pressed after a predetermined time has elapsed since the end of the previous printing operation, the operator determines whether or not there is actually a printing defect such as a deviation in the landing position. It is presumed that the operation switch 7d was pressed without confirmation. Therefore, in this case, the head maintenance unit control unit 37 controls the cleaning mechanism 39 via the cleaning mechanism drive circuit 40 to perform pseudo cleaning (step S5). That is, an extremely small amount of ink droplets smaller than the ejection amount in normal cleaning is ejected from the ink nozzle. When the pseudo cleaning is performed, the cleaning control ends.

  In this embodiment, steps S1 and S2 are dot missing determination steps, step S4 is an elapsed time determination step, step S3 is a normal cleaning step, and step S5 is a pseudo cleaning step. Further, in this embodiment, the head maintenance unit control unit 37 normally performs when the missing dot is detected, and when the elapsed time measured by the timer 41 is within a predetermined time when the missing dot is not detected. The cleaning mechanism 39 is controlled to perform cleaning, and the cleaning mechanism 39 is controlled to perform pseudo cleaning when the missing dot is not detected and the elapsed time measured by the timer 41 exceeds a predetermined time. Cleaning mechanism control means.

(Main effects of this embodiment)
As described above, in this embodiment, when the operation switch 7d is pressed, an ink droplet discharge inspection is performed. Based on the result of the ink droplet discharge inspection, it is determined that dot missing has occurred. Usually cleaning. For this reason, even when a predetermined time has elapsed from the end of the previous printing operation until the operation switch 7d is pressed, it is possible to eliminate missing dots without consuming recording paper. In addition, since it is determined whether or not dot missing has occurred based on the result of the ink droplet ejection test, it is compared with the case where it is determined whether or not dot missing has occurred by performing nozzle check pattern printing. As a result, it is possible to shorten the confirmation time for the occurrence of missing dots.

  Further, in this embodiment, even if it is determined that no dot dropout has occurred based on the result of the ink droplet discharge inspection, before a predetermined time elapses from the end of the previous printing operation, If it is determined that the operation switch 7d is pressed, normal cleaning is performed. For this reason, it is possible to eliminate problems such as deviations in the landing positions of ink droplets that cannot be detected by the ink droplet ejection inspection. Furthermore, in this embodiment, it is determined that no dot dropout has occurred based on the result of the ink droplet ejection inspection, and a predetermined time has elapsed since the end of the previous printing operation. If it is later determined that the operation switch 7d has been pressed, pseudo cleaning is performed. Therefore, useless consumption of ink droplets ejected from the ink nozzles can be suppressed.

(Other embodiments)
In the above-described embodiment, a very small amount of ink droplets smaller than the discharge amount in the normal cleaning is ejected from the ink nozzle by the pseudo cleaning. However, it is not necessary to eject the ink droplet from the ink nozzle by the pseudo cleaning. Further, if the ink consumption is smaller than the ejection amount in the normal cleaning, the ink suction operation may be performed in the pseudo cleaning. Further, a wiping operation may be performed instead of ejecting a very small amount of ink droplets from the ink nozzles by pseudo cleaning. That is, in the pseudo cleaning, it is sufficient that the ink droplets ejected from the ink nozzles are reduced as compared with the normal cleaning. In the above-described embodiment, the flushing operation and the ink suction operation are performed in the normal cleaning. However, only the flushing operation may be performed in the normal cleaning, or only the ink suction operation may be performed. Further, the flushing operation may not be performed in the normal cleaning.

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

  DESCRIPTION OF SYMBOLS 1 Inkjet printer (liquid ejection apparatus), 7d Operation switch (operation means), 14 Inkjet head (droplet ejection head), 33 Ink droplet ejection inspection mechanism (droplet ejection inspection mechanism), 37 Head maintenance unit control part (cleaning mechanism) Control means), 39 cleaning mechanism, 41 timer (time measuring means), S1 and S2 dot missing determination step, S3 normal cleaning step, S4 elapsed time determination step, S5 pseudo cleaning step

Claims (3)

Whether or not there is a missing dot in which the nozzle that does not discharge droplets exists when an operation means for manually starting cleaning of a liquid discharge head having a plurality of nozzles for discharging droplets is operated A missing dot determination step for determining whether or not the missing dot has occurred, and
If it is determined in the dot missing determination step that the dot missing has not occurred, it is determined whether or not the operation means has been operated before a predetermined time has elapsed since the end of the previous droplet discharge operation. An elapsed time determination step;
When it is determined in the dot missing determining step that the dot missing has occurred, and when it is determined in the elapsed time determining step that the operation means has been operated before the predetermined time has elapsed. A normal cleaning step for performing normal cleaning for discharging a predetermined amount of droplets from the nozzle;
In the elapsed time determining step, when it is determined that the operating means has been operated after the predetermined time has elapsed, a pseudo cleaning step of performing pseudo cleaning in which droplets ejected from the nozzles are reduced rather than the normal cleaning. And a control method of the liquid ejection apparatus. The liquid ejection head is an inkjet head having a plurality of the nozzles for ejecting ink droplets,
2. The method of controlling a liquid ejection apparatus according to claim 1, wherein in the elapsed time determination step, it is determined whether or not the operation means has been operated before the predetermined time has elapsed since the end of the previous printing. . A liquid discharge head having a plurality of nozzles for discharging liquid droplets;
A cleaning mechanism for cleaning the liquid discharge head;
Operation means for starting the cleaning mechanism by manually operating the cleaning mechanism;
A droplet discharge inspection mechanism that inspects whether or not there is a missing dot in which the nozzle that does not discharge droplets among the plurality of nozzles when the operation means is operated;
Time measuring means for measuring the elapsed time from the end of the previous droplet discharge operation until the operation means is operated;
When the dot dropout is detected by inspection by the droplet discharge inspection mechanism, and when the dot dropout is not detected but the elapsed time measured by the timing unit is within a predetermined time, The cleaning mechanism is controlled to perform normal cleaning for discharging a predetermined amount of droplets from the nozzle, and the dot dropout is not detected by the inspection by the droplet discharge inspection mechanism and is measured by the time measuring means. A cleaning mechanism control means for controlling the cleaning mechanism so as to perform pseudo cleaning in which droplets discharged from the nozzles are reduced rather than the normal cleaning when the elapsed time exceeds the predetermined time; A liquid ejecting apparatus.

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