JP2014094449A - Liquid jetting apparatus and cleaning method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a liquid jetting apparatus capable of suppressing useless consumption of liquid.SOLUTION: A liquid jetting apparatus includes: a liquid jetting head 19 for jetting ink from a plurality of nozzles 26; a piezoelectric element 40 for inspecting a jetted state of ink for each nozzle 26; a cleaning mechanism 22 capable of restoring a jetted state of ink from the nozzles 26; and a control part 47. The control part 47 performs: identifying a jetting-failed nozzle from among the individual nozzles 26 on the basis of the inspection result of the piezoelectric element 40 and storing the identified jetting-failed nozzle into a storage part 48; identifying a restoration-difficult nozzle, being difficult to restore a jetted state, from among the stored jetting-failed nozzles, and storing the identified restoration-difficult nozzle into the storage part 48; calculating a jetting-failure restoration ratio of the nozzles 26 expected when the cleaning mechanism performs cleaning, on the basis of the number of jetting-failed nozzles and the number of restoration-difficult nozzles, the numbers being stored in the storage part 48; and selecting a category of cleaning to be performed by the cleaning mechanism 22, on the basis of the calculated restoration ratio.

Description

  The present invention relates to a liquid ejecting apparatus such as an ink jet printer and a cleaning method for the liquid ejecting apparatus.

  2. Description of the Related Art Conventionally, an ink jet printer is widely known as an example of a liquid ejecting apparatus that ejects ink (liquid) from a plurality of nozzles formed in a recording head (liquid ejecting unit). In such printers, the ink may not be ejected well from the nozzles (ie, the nozzles are clogged) due to air bubbles in the ink or ink thickening, etc., so a cleaning mechanism that sucks the inside of the recording head through the nozzles It has.

  However, for example, if the ink thickens and solidifies, the cleaning performed by the cleaning mechanism may not sufficiently recover the nozzle clogging (ejection failure). For such nozzles that are difficult to recover from clogging (no-recoverable nozzles), it is unlikely that clogging will be recovered even if the same cleaning is repeated, and only ink is wasted. there were.

  Therefore, in order to suppress such wasteful ink consumption, it is possible to store nozzles that are difficult to recover from a plurality of clogged nozzles, and to determine whether there are nozzles that can recover from clogging other than those that are difficult to recover (recoverable nozzles). Printers that perform cleaning in response to this have been proposed. In such a printer, the strength of cleaning is adjusted according to the number of recoverable nozzles (for example, Patent Document 1).

JP 2009-178892 A

  By the way, even with cleaning that recovers clogging, cleaning according to the number of recoverable nozzles has the following problems. In other words, even if there is a high possibility of recovery of clogged nozzles detected as recoverable nozzles and recovery can be expected with weak cleaning, if there are a large number of target nozzles in that case, it is uniform. There is a possibility that ink is wasted by performing strong cleaning.

Such problems are not limited to printers that eject ink, but are generally common to liquid ejecting apparatuses that eject liquid.
The present invention has been made in view of such circumstances, and an object thereof is to provide a liquid ejecting apparatus capable of suppressing wasteful consumption of liquid.

Hereinafter, means for solving the above-described problems and the effects thereof will be described.
A liquid ejecting apparatus that solves the above problems includes a liquid ejecting unit that ejects liquid from a plurality of nozzles, an inspection unit that inspects the ejecting state of the liquid for each nozzle, and an ejecting state of the liquid from the nozzles. A cleaning mechanism capable of performing at least two types of cleaning that can be recovered when the ejection state is defective, and a first identification unit that identifies a defective ejection nozzle among the nozzles based on an inspection result of the inspection unit; A first storage unit that stores the ejection failure nozzles identified by the first identification unit; and a recovery difficulty nozzle that is difficult to recover from the ejection failure nozzles stored in the first storage unit. A second identification unit for identifying; a second storage unit for storing the difficult-to-recover nozzles identified by the second identification unit; and the number of ejection failure nozzles stored in the first storage unit Based on the number of difficult-to-recover nozzles stored in the second storage unit, a recovery rate of ejection failure of the nozzles when the cleaning mechanism performs one type of cleaning among the at least two types of cleaning. A calculation unit for calculating, and a selection unit for selecting a type of cleaning to be executed by the cleaning mechanism based on the recovery rate calculated by the calculation unit.

  According to this configuration, the recovery rate can be calculated in consideration of the number of difficult recovery nozzles. Therefore, when the selection unit selects the type of cleaning to be executed based on the recovery rate, it is possible to select the type of cleaning that is more suitable for the situation of the nozzle, and thus it is possible to suppress wasteful consumption of liquid. .

  In the liquid ejecting apparatus, it is preferable that the calculation unit calculates, as a recovery rate, a ratio of the number of nozzles recovered by the cleaning to the number of ejection defective nozzles that may be recovered before cleaning.

  According to this configuration, the number of ejection failure nozzles that can be recovered can be calculated by subtracting the number of difficult ejection nozzles from the number of ejection failure nozzles detected by the inspection unit. Further, the number of nozzles recovered by cleaning can be calculated by subtracting the number of defective injection nozzles after cleaning from the number of defective injection nozzles before cleaning. Therefore, the recovery rate accompanying cleaning can be easily calculated.

  In the liquid ejecting apparatus, the selection unit executes the first cleaning when the recovery rate is less than the recovery threshold, and is weaker than the first cleaning when the recovery rate is equal to or higher than the recovery threshold. It is preferable to perform the second cleaning.

  According to this configuration, when the recovery rate is large, the recovery of the nozzle can be expected even if a weak cleaning is selected. For this reason, when the recovery rate is high, the consumption of liquid can be reduced by selecting weak cleaning as compared with the case of selecting strong cleaning.

  In the liquid ejecting apparatus, the liquid ejecting unit further includes a liquid chamber that stores the liquid, and a piezoelectric element that changes a volume of the liquid chamber, and the inspection unit is configured to move from the nozzle to the piezoelectric element. It is preferable to output a drive signal for changing the volume of the liquid chamber within a range in which the liquid is not ejected and to acquire residual vibration information of the liquid chamber detected by the piezoelectric element.

  According to this configuration, it is possible to inspect whether or not the nozzle is an ejection failure nozzle without ejecting liquid from the nozzle. Therefore, the amount of liquid consumed as the nozzle recovers can be further reduced.

  Further, a cleaning method for solving the above problems includes a liquid ejecting unit that ejects liquid from a plurality of nozzles, an inspection unit that inspects the ejection state of the liquid for each nozzle, and an ejection state of the liquid from the nozzles. A cleaning method in a liquid ejecting apparatus comprising a cleaning mechanism capable of performing at least two types of cleaning that can be recovered when the ejection state is defective, and among the nozzles based on an inspection result of the inspection unit A first identification step for identifying defective injection nozzles from the first storage step for storing the defective injection nozzles identified in the first identification step, and the defective injection nozzles stored in the first storage step A second identification step for identifying a difficult-to-recover nozzle that is difficult to recover from, and a second memory for storing the difficult-to-recover nozzle identified in the second identification step And the cleaning mechanism selects one of the at least two types of cleaning based on the number of defective nozzles stored in the first storage step and the number of difficult recovery nozzles stored in the second storage step. A calculation step of calculating a recovery rate of the nozzle when the type of cleaning is executed, and a selection step of selecting a type of cleaning to be executed by the cleaning mechanism based on the recovery rate calculated in the calculation step.

  According to this configuration, the same operational effects as those of the liquid ejecting apparatus can be obtained.

1 is a schematic perspective view of a printer according to an embodiment. FIG. 3 is a plan view of a nozzle forming surface of a liquid ejecting head provided in the printer. FIG. 3 is a cross-sectional view illustrating a schematic configuration in a liquid ejecting head. The graph which shows the waveform of an electric signal. The flowchart of a cleaning process. The flowchart of a nozzle test subroutine.

Hereinafter, an embodiment of an ink jet printer (hereinafter also simply referred to as “printer”) as an example of a liquid ejecting apparatus will be described with reference to the drawings.
As shown in FIG. 1, a support member 13 for supporting the paper P at the time of printing is extended along the longitudinal direction in a frame 12 having a substantially rectangular box shape in the printer 11. The paper P is discharged from the printer 11 by being conveyed in the short direction (conveyance direction Y) of the support member 13 on the support member 13 by a PF motor 14 provided on the frame 12 and a paper feed mechanism (not shown). Is done.

  A guide shaft 15 is installed in the frame 12 along the longitudinal direction of the support member 13, and a carriage 16 is supported on the guide shaft 15 so as to be able to reciprocate along the axial direction of the guide shaft 15. Has been. That is, a support hole 16 a is formed in the carriage 16 so as to penetrate in the axial direction of the guide shaft 15, and the guide shaft 15 is inserted into the support hole 16 a, so that the carriage 16 is in the axial direction of the guide shaft 15. It can be reciprocated along (main scanning direction X).

  A wall surface is provided on the frame 12 along the guide shaft 15, and a driving pulley 17 a and a driven pulley 17 b are rotatably supported on the wall surface at positions substantially corresponding to both ends of the guide shaft 15. The drive pulley 17a is connected to an output shaft of a CR motor 18 which is a drive source for reciprocating the carriage 16, and a part of the drive pulley 17a and the driven pulley 17b is connected to the carriage 16. An endless timing belt 17 is wound around. Accordingly, the carriage 16 reciprocates in the main scanning direction X via the endless timing belt 17 by the driving force of the CR motor 18 while being guided by the guide shaft 15.

  A liquid ejecting head 19 as an example of a liquid ejecting unit that forms (prints) an image on the paper P by ejecting ink is disposed at a position facing the support member 13 of the carriage 16 with a predetermined gap. Provided. In the moving area of the carriage 16 in the main scanning direction X, the ejection characteristics of the liquid ejecting head 19 are maintained in a non-printing area (home position area) where the conveyed paper P and the liquid ejecting head 19 do not face each other. A cleaning mechanism 22 is provided in the frame 12.

  Ink cartridges 20 and 21 for supplying ink to the liquid ejecting head 19 are detachably mounted on the carriage 16. In the printer 11 of the present embodiment, the ink cartridge 20 stores black ink, and the ink cartridge 21 stores cyan, magenta, and yellow color inks. Each color ink is supplied from the ink cartridges 20, 21 to the liquid ejecting head 19, and is conveyed on the support member 13 from the nozzle forming surface 25 provided on the lower side of the liquid ejecting head 19 facing the support member 13. And printing is performed.

  That is, as shown in FIG. 2, the lower surface of the liquid jet head 19 that faces the support member 13 is a nozzle forming surface 25 on which a plurality of nozzles 26 are formed. On the nozzle forming surface 25, at least one (four in this embodiment) nozzle row 27 (27a, 27a, 27) in which a plurality of nozzles 26 are arranged along the transport direction Y orthogonal to the main scanning direction X. 27b, 27c, and 27d) are provided at intervals in the main scanning direction X, respectively.

  As shown in FIG. 3, the liquid ejecting head 19 includes a group of members stacked in the vertical direction, that is, a flow path forming member 32, a vibration plate 33, a flow path forming member 34, and a nozzle plate 35 in order from the top. Yes. The flow path forming member 32 is formed with a reservoir 36 communicating with a common ink chamber (not shown) and a storage chamber 37. The diaphragm 33 is provided with a communication hole 38 at a position corresponding to the reservoir 36. The flow path forming member 34 is formed with a cavity 39 as an example of a liquid chamber that communicates with the reservoir 36 through the communication hole 38 and stores ink.

  A piezoelectric element 40 is disposed on the upper surface side of the diaphragm 33 at a position above the cavity 39. A nozzle 26 communicating with the cavity 39 is formed in the nozzle plate 35. That is, the ink is supplied from the reservoir 36 to the nozzle 26 through the communication hole 38 and the cavity 39.

  The diaphragm 33 is disposed between the upper flow path forming member 32 and the lower flow path forming member 34 so as to vibrate in the vertical direction, and the piezoelectric element 40 expands and contracts in response to the drive signal. By doing so, the diaphragm 33 is vibrated in the vertical direction. Further, when the diaphragm 33 vibrates in the vertical direction, the volume of the cavity 39 changes (expands / contracts). When the volume of the cavity 39 is reduced, the ink in the cavity 39 is ejected from the nozzle 26 as ink droplets.

  The reservoir 36, the storage chamber 37, the communication hole 38, the cavity 39, and the piezoelectric element 40 are individually provided corresponding to each nozzle 26, and the reservoirs 36 communicate with each other via a common ink chamber (not shown). ing. Further, the nozzle forming surface 25 of the liquid jet head 19 is constituted by the lower surface (bottom surface) of the nozzle plate 35.

  The cleaning mechanism 22 has a bottomed square box shape that can come into contact with the nozzle forming surface 25, a lifting mechanism 43 that lifts and lowers the cap 42, a suction pump 44 that sucks the inside of the cap 42, And a discharge tube 45. When the suction pump 44 sucks the closed space surrounded by the cap 42 and the nozzle forming surface 25 that is in contact with the nozzle forming surface 25, the ink is discharged from the nozzle 26 into the cap 42, and then the inside of the cap 42. To the waste ink tank (not shown) through the discharge tube 45. That is, the cleaning mechanism 22 performs cleaning that can recover the ejection state of the ink from the nozzles when the ejection state is defective.

Next, the electrical configuration of the printer 11 of this embodiment will be described.
As shown in FIG. 3, the printer 11 is provided with a control unit 47 that performs overall control of the operating state of the printer 11. The control unit 47 includes a storage unit 48 that stores various programs. Based on the program, the control unit 47 drives and controls the PF motor 14, the CR motor 18, each piezoelectric element 40, the lifting mechanism 43, and the suction pump 44 to perform printing. And cleaning.

  The control unit 47 changes the magnitude of the negative pressure (negative pressure applied to the nozzle 26) generated in the cap 42 by changing the driving speed and driving time of the suction pump 44, so that at least 2 Causes the cleaning mechanism 22 to perform the type of cleaning. Specifically, the suction force increases as the drive speed of the suction pump 44 increases, and the suction amount increases as the drive time increases. Therefore, the control unit 47 selects and executes the strong cleaning as an example of the first cleaning and the weak cleaning as an example of the second cleaning that is weaker than the strong cleaning. Note that the strong cleaning of the present embodiment is a cleaning in which the driving speed of the suction pump 44 is higher and the driving time is longer than that of the weak cleaning. For this reason, the amount of ink consumed with strong cleaning is larger than the amount of ink consumed with weak cleaning.

Next, a method for inspecting the ink ejection state in the nozzle 26 will be described.
The piezoelectric element 40 of the present embodiment also functions as an example of an inspection unit that inspects the ink ejection state for each nozzle 26. In the following description, the defective ejection nozzle refers to the nozzle 26 in a state where the ink cannot be ejected or an appropriate amount of ink cannot be ejected due to clogging of the nozzle 26, thickening of ink, mixing of bubbles, or the like. Further, a nozzle that is difficult to recover is a nozzle 26 that has been identified as having difficulty in recovering the injection state because the injection state has not recovered even though cleaning has been performed at least twice (in this embodiment, three times). Indicates.

  As shown in FIG. 3, the controller 47 outputs a nozzle inspection drive signal to the piezoelectric element 40. The nozzle inspection drive signal is a drive signal for changing the volume of the cavity 39 within a range in which residual vibration is generated without ejecting ink from the nozzle 26. Then, the piezoelectric element 40 outputs an electrical signal corresponding to the residual vibration that is the vibration of the ink in the cavity 39 to the control unit 47 as residual vibration information.

In FIG. 4, an example of an electrical signal acquired as residual vibration information by the control unit 47 is illustrated as a waveform with the voltage V on the vertical axis and the time t on the horizontal axis.
Now, as shown in FIG. 4, it is assumed that the reference signal A indicated by the solid line is obtained in a state where ink can be ejected from the nozzle 26 satisfactorily. For example, when bubbles are generated in the ink in the cavity 39 and the ink cannot be ejected with respect to the reference signal A, the cycle is shortened as in the first ejection failure signal B indicated by a one-dot chain line. On the other hand, for example, when the ink in the cavity 39 is thickened and the ink cannot be ejected, the cycle becomes longer with respect to the reference signal A like the second ejection failure signal C indicated by the dotted line. Note that the first injection failure signal B and the second injection failure signal C show waveforms when good injection cannot be performed from a state where injection was good.

  In the present embodiment, the controller 47 determines whether or not the ejection state of the ink from the nozzle 26 is defective from the half-cycle time t1 of the first ejection failure signal B to the half-cycle time t2 of the second ejection failure signal C. A threshold time Tt (t1 <Tt <t2) for determination is set. That is, the control unit 47 determines that the ejection state of the nozzle 26 is normal if the half-cycle time of the acquired electrical signal is within the threshold time Tt (greater than t1 and less than t2). On the other hand, the controller 47 determines that the ejection state of the nozzle 26 is defective if the half-cycle time of the acquired electrical signal is outside the range of the threshold time Tt (t1 or less or t2 or more).

  In this respect, the control unit 47 also functions as an example of a first identification unit that identifies an ejection failure nozzle among the nozzles 26 based on the inspection result of the piezoelectric element 40. Note that the threshold time Tt differs depending on the size and shape of the cavity 39 and the type of ink, and is a time set by an experiment prior to factory shipment, and is stored in the storage unit 48 at the time of factory shipment.

  Next, the cleaning process that the control unit 47 causes the cleaning mechanism 22 to execute will be described based on the flowchart of FIG. The control unit 47 starts the cleaning process by the cleaning mechanism 22 by executing a cleaning process routine when the printer 11 is turned on or when a predetermined time has elapsed since the previous cleaning.

  As shown in FIG. 5, when the cleaning process is started, the control unit 47 first executes a nozzle inspection subroutine in step S101. The specific contents of the nozzle inspection subroutine will be described based on the flowchart of FIG.

  As shown in FIG. 6, when the nozzle inspection subroutine is started, the control unit 47 first outputs a drive signal for nozzle inspection in step S201, and acquires residual vibration information in step S202. Furthermore, in step S203, the control unit 47 compares the half cycle time of the electrical signal with the threshold time Tt based on the acquired residual vibration information, and identifies an ejection failure nozzle (an example of a first identification step). That is, when the half cycle time is outside the range of the threshold time Tt (step S203: YES), the control unit 47 identifies the inspected nozzle 26 as an ejection failure nozzle having a failure ejection state, and step S204. Migrate to

  In step S204, the control unit 47 determines whether or not the nozzle 26 to be inspected is stored in the storage unit 48 as a difficult recovery nozzle. If it is stored as a difficult-to-recover nozzle (step S204: YES), the process proceeds to step S208. On the other hand, when it is not stored as a difficult-to-recover nozzle (step S204: NO), the control unit 47 proceeds to step S205.

  In step S205, the control unit 47 associates the identifier of the nozzle 26 determined to be an ejection failure nozzle in step S203 with the number of times determined to be defective (hereinafter referred to as “number of defects”) in the storage unit 48. Store (an example of a first storage step). That is, for example, when the identifier of the nozzle 26 is stored in advance, the number of defects is incremented (plus 1). In this respect, the storage unit 48 also functions as an example of a first storage unit that stores ejection failure nozzles.

  Further, in step S206, the control unit 47 determines whether or not the number of defects is equal to or greater than a threshold number (for example, 3 times), and identifies a nozzle that is difficult to recover (an example of a second identification step). That is, when the inspected nozzle 26 is continuously detected as the ejection failure nozzle a threshold number of times (step S206: YES), the control unit 47 identifies that the inspected nozzle 26 is a difficult-to-recover nozzle. In this respect, the control unit 47 also functions as an example of a second identification unit that identifies difficult-to-recover nozzles from among ejection failure nozzles.

  In step S207, the control unit 47 stores the identifier of the nozzle 26 determined to be a difficult recovery nozzle in the storage unit 48 (an example of a second storage step). In this respect, the storage unit 48 also functions as an example of a second storage unit that stores the identified difficult recovery nozzle.

  On the other hand, when it is determined in step S206 that the number of defects is less than the threshold number (step S206: NO), the control unit 47 shifts the process to step S208. In step S208, the control unit 47 determines whether or not all the nozzles 26 have been inspected. If all the nozzles 26 have been inspected (step S208: YES), the nozzle inspection routine ends. . On the other hand, when there is a nozzle 26 that has not been inspected (step S208: NO), the control unit 47 moves the process to step S201, and for the piezoelectric element 40 corresponding to the next nozzle 26 that has not been inspected. A drive signal for nozzle inspection is output.

  In step S203, when the half cycle time is within the threshold time Tt (step S203: NO), the control unit 47 stores the nozzle 26 to be inspected in the storage unit 48 as an ejection failure nozzle in step S209. It is judged whether it is done. If it is not stored as an ejection failure nozzle (step S209: NO), the control unit 47 proceeds to step S208. On the other hand, if it is stored as an ejection failure nozzle (step S209: YES), the control unit 47 deletes the ejection failure nozzle identifier and the number of failures stored in the storage unit 48 in step S210.

  Subsequently, in step S211, the control unit 47 determines whether or not the nozzle 26 to be inspected is stored in the storage unit 48 as a difficult recovery nozzle. If it is stored as a difficult-to-recover nozzle (step S211: YES), the control unit 47 deletes the identifier of the difficult-to-recover nozzle stored in the storage unit 48 in step S212. On the other hand, when it is not stored as a difficult-to-recover nozzle (step S211: NO), the controller 47 shifts the process to step S208. When the nozzle inspection routine ends, the control unit 47 returns the process to the flowchart of the cleaning process routine shown in FIG.

  As shown in FIG. 5, when the control unit 47 ends the nozzle inspection subroutine in step S101, it determines in step S102 whether there is an injection nozzle that can be recovered. That is, when there is no defective injection nozzle, or when all the defective injection nozzles are difficult to recover, the control unit 47 determines that there is no recoverable defective nozzle (step S102: NO). Then, the cleaning process routine is terminated. On the other hand, when there is an ejection failure nozzle that is not a difficult recovery nozzle, the control unit 47 determines that there is an ejection failure nozzle that may be recovered (step S102: YES), and the process proceeds to step S103. .

  In step S103, the control unit 47 newly stores the number of ejection failure nozzles stored in the storage unit 48 in the storage unit 48, and in step S104, the number of difficult recovery nozzles stored in the storage unit 48. Is newly stored in the storage unit 48. Further, in step S105, the control unit 47 controls the driving of the lifting mechanism 43 and the suction pump 44 to execute weak cleaning, and in step S106, the nozzle inspection subroutine is executed in the same manner as in step S101.

  In step S107, the control unit 47 recovers the ratio of the number of nozzles 26 recovered by the cleaning executed in step S105 to the number of ejection failure nozzles that can be recovered before cleaning in step S105. It is calculated as a rate (an example of a calculation process). In this respect, the control unit 47 also functions as an example of a calculation unit that calculates a recovery rate of nozzle ejection failure when cleaning is performed.

  The number of nozzles that can be recovered before cleaning can be calculated by subtracting the number of difficult-to-recover nozzles stored in step S104 from the number of ejection failure nozzles stored in step S103. Further, the number of nozzles 26 recovered by cleaning can be calculated by subtracting the number of defective ejection nozzles updated in step S106 from the number of defective ejection nozzles stored in step S103.

  Therefore, for example, assuming that the number of ejection failure nozzles stored in step S103 is 30, the number of difficult recovery nozzles stored in step S104 is 10, and the number of ejection failure nozzles detected in step S106 is 20, the recovery rate. Is calculated by the formula: recovery rate = {(30−20) / (30−10)} × 100.

  When all the ejection failure nozzles that can be recovered are recovered, the recovery rate is 100% (step S108: YES), and the control unit 47 ends the cleaning processing routine. Further, in the case of the above example, since all the ejection failure nozzles that can be recovered by the cleaning in step S105 have not recovered, the recovery rate does not become 100% (in the example, 50%, step S108: NO). The control unit 47 shifts the process to step S109.

  In step S109, the control unit 47 updates the number of defective ejection nozzles stored in the storage unit 48 with the number of defective ejection nozzles detected in step S106. Further, in step S110, the control unit 47 updates the number of difficult recovery nozzles stored in the storage unit 48 with the number of difficult recovery nozzles detected in step S106.

  In step S111, the control unit 47 compares the recovery threshold (for example, 50%) stored in advance in the storage unit 48 with the recovery rate calculated in step S107, and then selects the cleaning to be executed by the cleaning mechanism 22. (An example of a selection process). The recovery threshold value is a threshold value stored in advance in the storage unit 48 in order to select cleaning to be performed. When the calculated recovery rate is equal to or higher than the recovery threshold (step S111: YES), the control unit 47 executes weak cleaning (step S112). On the other hand, if the calculated recovery rate is less than the recovery threshold (step S111: NO), strong cleaning is executed (step S113). In this respect, the control unit 47 also functions as an example of a selection unit that selects the type of cleaning to be performed by the cleaning mechanism 22 based on the recovery rate.

  Subsequently, in step S114, the control unit 47 executes a nozzle inspection subroutine in the same manner as in step S101. In step S115, the control unit 47 determines whether there is an injection nozzle that can be recovered in the same manner as in step S102. When there is no ejection failure nozzle that can be recovered (step S115: NO), the control unit 47 ends the cleaning process routine. On the other hand, if there is an ejection failure nozzle that may be recovered (step S115: YES), the control unit 47 shifts the process to step S107.

  That is, in subsequent S107, the control unit 47 calculates the recovery rate based on the number of defective injection nozzles updated in step S109, the number of difficult recovery nozzles updated in step S110, and the number of defective injection nozzles detected in step S114. To do.

Next, the operation when the cleaning mechanism 22 performs cleaning will be described.
When the cleaning is executed in the printer 11, the control unit 47 drives the elevating mechanism 43 to bring the cap 42 into contact with the nozzle forming surface 25. Further, the controller 47 drives the suction pump 44 to perform weak cleaning. Then, ink is discharged from the nozzle 26 covered with the cap 42.

  When all of the ejection failure nozzles are recovered by cleaning, the control unit 47 drives the lifting mechanism 43 to separate the cap 42 from the nozzle forming surface 25 and drives the suction pump 44 to drive the inside of the cap 42. Ink is discharged to a waste liquid tank (not shown). In addition, when the ejection failure nozzle remains, the control unit 47 drives the suction pump 44 in a driving mode based on the recovery rate to execute strong cleaning or weak cleaning. Note that the control unit 47 repeatedly executes strong cleaning or weak cleaning until there is no ejection failure nozzle that is not a difficult recovery nozzle. When there is no ejection failure nozzle, the controller 47 drives the elevating mechanism 43 to separate the cap 42 from the nozzle forming surface 25 and drives the suction pump 44 to remove the ink in the cap 42 from the waste liquid tank (illustrated). Omission).

According to the above embodiment, the following effects can be obtained.
(1) The recovery rate can be calculated in consideration of the number of difficult recovery nozzles. Therefore, when the control unit 47 selects the type of cleaning to be executed based on the recovery rate, it is possible to select the type of cleaning that is more suitable for the situation of the nozzles 26, thereby suppressing wasteful consumption of ink. Can do.

  (2) The number of ejection failure nozzles that can be recovered can be calculated by subtracting the number of difficult ejection nozzles from the number of ejection failure nozzles detected by the control unit 47. Furthermore, the number of nozzles 26 recovered by cleaning can be calculated by subtracting the number of defective injection nozzles after cleaning from the number of defective injection nozzles before cleaning. Therefore, the recovery rate accompanying cleaning can be easily calculated.

  (3) When the recovery rate is large, recovery of the nozzle 26 can be expected even if weak cleaning is selected. Therefore, when the recovery rate is large, the ink consumption can be reduced by selecting the weak cleaning as compared with the case of selecting the strong cleaning.

  (4) It is possible to inspect whether or not the nozzle is an ejection failure nozzle without ejecting ink from the nozzle 26. Therefore, the amount of ink consumed as the nozzle 26 is recovered can be further reduced.

In addition, you may change the said embodiment as follows.
In the above embodiment, whether the inspected nozzle 26 is a poorly ejected nozzle may be identified based on the waveform shape of an electrical signal acquired as residual vibration information. Further, when it is difficult to identify whether or not the nozzle is an ejection failure nozzle, a nozzle inspection drive signal may be output to the piezoelectric element 40 again and reinspected. Then, the number of reinspections may be stored in the storage unit 48 and used when selecting the type of cleaning.

  In the above embodiment, when the cleaning process is performed, the weak cleaning is first executed in step S105, but the strong cleaning may be executed. Further, instead of suction cleaning, flushing that ejects ink from the nozzles 26 may be executed as cleaning.

  In the above embodiment, the drive signal for nozzle inspection may be a signal to the extent that ink is ejected from the nozzle 26. Even when ink is ejected from the nozzle 26, the ejection state of the nozzle 26 can be inspected by detecting the residual vibration of the cavity 39.

  In the above embodiment, a voltage is applied between the cap 42 and the nozzle forming surface 25 to detect electrostatic induction when the ink is ejected and a potential difference generated when the charged ink lands on the cap 42. You may provide the test | inspection part which test | inspects the injection condition of the nozzle 26 based on a signal. In this case, the piezoelectric element 40 may not be provided, and for example, bubbles may be generated in the cavity 39 and ink may be ejected from the nozzles 26.

  In the above embodiment, weak cleaning may be executed when the recovery rate is greater than the recovery threshold, and strong cleaning may be executed when the recovery rate is less than or equal to the recovery threshold. Further, strong cleaning may be executed when the recovery rate is equal to or higher than the recovery threshold (or larger than the recovery rate), and weak cleaning may be executed when the recovery rate is less than the threshold (or lower than the recovery rate).

  In the above embodiment, the control unit 47 may perform three or more types of cleaning by changing the driving speed and driving time of the suction pump 44. That is, for example, two or more recovery threshold values may be set, and cleaning may be selected from three or more types based on two or more recovery threshold values.

  In the above embodiment, the cleaning may be performed by so-called flushing in which ink is ejected from the nozzle 26. That is, for example, the first flushing with a large number of ejections may be performed as the first cleaning, and the second flushing with a smaller number of ejections than the first flushing may be performed as the second cleaning. In this case, the cleaning mechanism 22 may not be provided, and the piezoelectric element 40 functions as an example of the cleaning mechanism.

  In the above embodiment, the recovery rate may be a ratio of the number of nozzles 26 recovered by cleaning plus the number of difficult recovery nozzles to the number of ejection failure nozzles before cleaning. That is, assuming that the number of ejection failure nozzles before cleaning is 30, the number of difficult recovery nozzles stored in step S104 is 20, and the number of ejection failure nozzles after cleaning is 10, the recovery rate is recovery rate = {(30 -20 + 10) / 30} × 100.

  In the above embodiment, at least two caps 42 may be provided so as to correspond to at least one nozzle row. Further, the cap 42 may be partitioned so as to correspond to at least one nozzle row. Then, the cleaning may be executed in units of nozzle rows 27 having recoverable ejection failure nozzles.

  In the above embodiment, the liquid ejecting apparatus may be a liquid ejecting apparatus that ejects or discharges liquid other than ink. Note that the state of the liquid ejected as a minute amount of liquid droplets from the liquid ejecting apparatus includes a granular shape, a tear shape, and a thread-like shape. The liquid here may be any material that can be ejected from the liquid ejecting apparatus. For example, it may be in a state in which the substance is in a liquid phase, such as a liquid with high or low viscosity, sol, gel water, other inorganic solvents, organic solvents, solutions, liquid resins, liquid metals (metal melts ). Further, not only a liquid as one state of a substance but also a substance in which particles of a functional material made of a solid such as a pigment or a metal particle are dissolved, dispersed or mixed in a solvent is included. Typical examples of the liquid include ink and liquid crystal as described in the above embodiment. Here, the ink includes general water-based inks and oil-based inks, and various liquid compositions such as gel inks and hot melt inks. As a specific example of the liquid ejecting apparatus, for example, a liquid containing a material such as an electrode material or a color material used for manufacturing a liquid crystal display, an EL (electroluminescence) display, a surface emitting display, or a color filter in a dispersed or dissolved form. There is a liquid ejecting apparatus for ejecting the liquid. Further, it may be a liquid ejecting apparatus that ejects a bio-organic matter used for biochip manufacturing, a liquid ejecting apparatus that ejects liquid as a sample that is used as a precision pipette, a printing apparatus, a micro dispenser, or the like. In addition, transparent resin liquids such as UV curable resin to form liquid injection devices that pinpoint lubricant oil onto precision machines such as watches and cameras, and micro hemispherical lenses (optical lenses) used in optical communication elements. May be a liquid ejecting apparatus that ejects the liquid onto the substrate. Further, it may be a liquid ejecting apparatus that ejects an etching solution such as acid or alkali in order to etch a substrate or the like.

  DESCRIPTION OF SYMBOLS 11 ... Printer (an example of a liquid ejecting apparatus), 19 ... Liquid ejecting head (an example of a liquid ejecting part), 22 ... Cleaning mechanism, 26 ... Nozzle, 39 ... Cavity (an example of a liquid chamber), 40 ... Piezoelectric element (inspection part) ), 47... Control unit (example of first identification unit, example of second identification unit, example of calculation unit, example of selection unit), 48... Storage unit (example of first storage unit, second storage unit) Example).

Claims (5)

A liquid ejecting section that ejects liquid from a plurality of nozzles;
An inspection unit for inspecting the ejection state of the liquid for each nozzle;
A cleaning mechanism capable of performing at least two types of cleaning that can recover the ejection state of the liquid from the nozzle when the ejection state is defective;
A first identification unit that identifies an ejection failure nozzle among the nozzles based on an inspection result of the inspection unit;
A first storage unit that stores the ejection failure nozzles identified by the first identification unit;
A second identification unit for identifying a difficult-to-recover nozzle that is difficult to recover from an ejection state among the defective ejection nozzles stored in the first storage unit;
A second storage unit that stores the difficult-to-recover nozzle identified by the second identification unit;
Based on the number of defective ejection nozzles stored in the first storage unit and the number of difficult recovery nozzles stored in the second storage unit, the cleaning mechanism is one of the at least two types of cleaning. A calculation unit that calculates a recovery rate of the ejection failure of the nozzle when the cleaning is performed;
A liquid ejecting apparatus comprising: a selection unit that selects a type of cleaning to be performed by the cleaning mechanism based on the recovery rate calculated by the calculation unit. The said calculating part calculates the ratio of the number of the said nozzles recovered | restored by the said cleaning with respect to the number of the said ejection failure nozzles with the possibility of recovery before cleaning as a recovery rate. Liquid ejector. The selection unit executes the first cleaning when the recovery rate is less than the recovery threshold, and executes the second cleaning that is weaker than the first cleaning when the recovery rate is equal to or higher than the recovery threshold. The liquid ejecting apparatus according to claim 1, wherein the liquid ejecting apparatus is a liquid ejecting apparatus. The liquid ejecting unit includes a liquid chamber for storing the liquid,
A piezoelectric element that changes the volume of the liquid chamber;
The inspection unit outputs a drive signal for changing the volume of the liquid chamber within a range in which the liquid is not ejected from the nozzle to the piezoelectric element, and the residual vibration information of the liquid chamber detected by the piezoelectric element. The liquid ejecting apparatus according to claim 1, wherein the liquid ejecting apparatus is acquired. A liquid ejecting section that ejects liquid from a plurality of nozzles;
An inspection unit for inspecting the ejection state of the liquid for each nozzle;
A cleaning method in a liquid ejecting apparatus comprising: a cleaning mechanism capable of performing at least two types of cleaning that can recover the ejected state of the liquid from the nozzle when the ejected state is defective,
A first identification step for identifying an ejection failure nozzle among the nozzles based on an inspection result of the inspection unit;
A first storage step of storing the ejection failure nozzle identified in the first identification step;
A second identification step for identifying difficult-to-recover nozzles that are difficult to recover from the poorly ejected nozzles stored in the first storage step;
A second storage step of storing the difficult-to-recover nozzle identified in the second identification step;
Based on the number of ejection failure nozzles stored in the first storage step and the number of difficult recovery nozzles stored in the second storage step, the cleaning mechanism performs one type of cleaning among the at least two types of cleaning. Calculating step of calculating the recovery rate of the nozzle when
And a selection step of selecting a type of cleaning to be performed by the cleaning mechanism based on the recovery rate calculated in the calculation step.