JP2017013301A - Liquid injection device and maintenance method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a liquid injection device being capable of appropriately performing maintenance of an injection head having nozzles while suppressing wasteful consumption of liquid, and a maintenance method.SOLUTION: A liquid injection device comprises: an injection head 13 on which a plurality of nozzles 12 capable of injecting liquid are opened; a wiping member 51 performing wiping of a region including nozzle openings 12a of the injection head 13; a pressure adjustment mechanism 16 capable of adjusting a pressure of the liquid in the nozzle 12 for each nozzle 12; a detection section capable of detecting whether a state of the nozzle 12 is good or defective for each nozzle 12; and a control section causing the wiping member 51 to execute the wiping in a state where a liquid surface is swollen from the nozzle opening 12a by causing the pressure adjustment mechanism 16 to execute pressure increasing operation for increasing the pressure of the liquid in the nozzle 12 in comparison with that at the time of liquid injection with respect to a defective nozzle detected as being defective by the detection section.SELECTED DRAWING: Figure 4

Description

  The present invention relates to a liquid ejecting apparatus such as a printer and a maintenance method.

  In an ink jet printer, which is an example of a liquid ejecting apparatus, the inside of a nozzle that ejects liquid normally has a negative pressure, but pressurization that wipes the area where the nozzle opens in a state where the inside of the nozzle is at a positive pressure Wiping may be performed (for example, Patent Document 1).

JP 2004-291618 A

  When the pressure inside the nozzle is set to a positive pressure as described above, the ink flows out through the wiping member when the wiping member for wiping comes into contact with the liquid surface of the ink. Etc. can be discharged from the nozzle to eliminate the injection failure. However, there is a problem that the ink used for printing is consumed by the amount of liquid flowing out of the nozzle along with wiping.

  In addition, such a problem is not limited to a printer that performs printing by ejecting ink, but in an ejection head in which a plurality of nozzles capable of ejecting liquid are opened, when wiping an area including the opening of the nozzle, It is almost common.

  The present invention has been made in view of such circumstances, and an object thereof is to provide a liquid ejecting apparatus and a maintenance method that can appropriately perform maintenance of an ejecting head having a nozzle while suppressing wasteful consumption of liquid. It is to provide.

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 an ejecting head in which a plurality of nozzles capable of ejecting liquid are opened, a wiping member that wipes an area including the nozzle opening of the ejecting head, and a pressure of the liquid in the nozzle. With respect to the pressure adjustment mechanism that can be adjusted for each nozzle, the detection unit that can detect whether the state of the nozzle is good or bad for each nozzle, and the defective nozzle that is detected that the detection unit is defective, Control that causes the wiping member to perform the wiping in a state where the liquid level is swollen from the nozzle opening by causing the pressure adjustment mechanism to perform a pressure increasing operation for increasing the pressure of the liquid in the nozzle as compared with the time of liquid ejection. A section.

  According to this configuration, the defective nozzle detected as defective by the detection unit is wiped with the liquid level bulging from the nozzle opening due to the pressure increase in the nozzle, so the wiping member is swollen from the defective nozzle. By contacting the discharged liquid surface, foreign matter or the like that exists in the nozzle and causes the ejection failure can be discharged together with the liquid, and the ejection failure can be appropriately solved. At this time, since the pressure increasing operation for increasing the pressure in the nozzle is performed on the defective nozzle, the wiping member is unlikely to contact the normal nozzle surface, and even if the wiping member contacts the liquid surface. Liquid outflow is suppressed. Accordingly, it is possible to appropriately perform maintenance of the ejection head having the nozzle while suppressing wasteful consumption of the liquid.

  In the liquid ejecting apparatus, the ejecting head includes a plurality of nozzle groups including a plurality of the nozzles, and the pressure adjusting mechanism is capable of adjusting the pressure of the liquid in the nozzles for each of the nozzle groups, When the pressure increasing operation for increasing the pressure of the liquid in the nozzle so that the liquid level swells from the opening is the first pressure increasing operation, the control unit causes the pressure adjusting mechanism to connect the defective nozzle to the wiping operation. The first pressure increasing operation is executed for the defective nozzle group including the second pressure increasing operation, and the second pressure increasing operation is performed for the normal nozzle group not including the defective nozzle.

  According to this configuration, the defective nozzle group is wiped with the liquid level bulged from the nozzle, so that the wiping member is in contact with the liquid level bulged from the defective nozzle and is present in the nozzle. Foreign matter or the like that causes the ejection failure can be discharged together with the liquid, and the ejection failure can be appropriately eliminated. On the other hand, in the normal nozzle group, since the degree of pressure increase in the nozzle is smaller than that in the defective nozzle group, the wiping member is less likely to come into contact with the liquid surface. Since the amount is smaller than that of the defective nozzle group, wasteful consumption of liquid is suppressed. When the pressure in the nozzle is negative, the lower the pressure is, the more the liquid level is drawn into the nozzle, and the outflow of liquid due to the wiping member coming into contact with the liquid level is suppressed. However, the greater the negative pressure in the nozzle and the liquid level entering the nozzle, the easier it is for the wiping member to pass through the nozzle opening and forcing foreign objects and bubbles into the nozzle. May be induced. In that respect, if the pressure of the liquid in the nozzles is also increased for the normal nozzle group, it is possible to suppress the occurrence of injection failure due to the insertion of foreign matter or the like into the nozzles.

  The liquid ejecting apparatus includes a supply mechanism for pressurizing and supplying liquid toward the ejecting head, the ejecting head includes a plurality of nozzle groups including the plurality of nozzles, and the pressure adjusting mechanism includes the nozzle Pressure that is provided for each group and has an inflow hole through which liquid to be supplied under pressure and an outflow hole communicating with the nozzle group, and a movable wall that can be displaced in the direction of changing the internal volume constitutes a part of the wall surface A valve body that is displaceable between a chamber, a closed position that closes the inflow hole, and an open position that opens the inflow hole, a biasing member that biases the valve body toward the closed position, and the valve body A valve opening mechanism that moves the valve toward the open position, and in the pressure adjusting mechanism, when the liquid is ejected, the liquid flows out from the outflow hole, and the pressure chamber has a negative pressure. As it declines, The movable wall that is displaced in the direction of decreasing the internal volume of the pressure chamber moves the valve body to the valve opening position against the urging force of the urging member, so that the liquid pressurized from the inflow hole To increase the pressure in the pressure chamber, and when wiping, the valve opening mechanism moves the valve body to the open position against the urging force of the urging member. The pressurized liquid is caused to flow from the pressure chamber to increase the pressure in the pressure chamber and the nozzle.

  According to this configuration, the pressure in the nozzle can be increased by forcibly moving the valve body that adjusts the pressure in the pressure chamber by moving with the consumption of the liquid by the valve opening mechanism. In other words, a valve opening mechanism may be added to the pressure adjustment mechanism for adjusting the pressure in the pressure chamber, so that compared with the case where a dedicated pressure adjustment mechanism is provided to adjust the pressure in the nozzle during wiping. Therefore, it is possible to prevent the apparatus configuration from becoming complicated.

  In the liquid ejecting apparatus, when the ejecting head includes a plurality of nozzle groups including the plurality of nozzles, and the pressure adjusting mechanism can adjust the pressure state in the nozzles for each nozzle group, the nozzles A suction mechanism capable of performing suction cleaning for sucking a closed space to be opened for each of the nozzle groups, and performing the pressure increasing operation for increasing the pressure of the liquid in the nozzle so that the liquid level swells from the nozzle opening. When the first pressure increasing operation is performed, the control unit performs the pressure adjustment with respect to all the nozzle groups after the suction cleaning is performed with the second pressure increasing operation in which the degree of pressure increase is smaller than that of the first pressure increasing operation. The said wiping member is made to perform the said wiping in the state made to perform by the mechanism.

  After the suction cleaning for sucking the closed space where the nozzles are opened, since the liquid adheres to the ejection head, it is preferable to wipe off such liquid by the wiping member. However, when selective suction cleaning is performed on a defective nozzle group including defective nozzles that have caused ejection failure, wiping with a negative pressure inside the nozzle is performed on normal nozzle groups that have not been suction cleaned. If it does, when a wiping member passes a nozzle opening, the foreign material and bubble which exist around will be pushed in in a nozzle, and there exists a possibility of inducing the injection defect on the contrary. Further, with respect to the nozzle group that has been subjected to suction cleaning, foreign matter and the like in the nozzle have already been discharged by suction, so there is no need to allow liquid to flow out of the nozzle. In that respect, according to the above-described configuration, when the ejection head is wiped after the suction cleaning is performed, the second pressure increase operation for increasing the pressure in the nozzles to the extent that the outflow of the liquid is suppressed is suppressed for all the nozzle groups. Since the adjustment mechanism is executed, it is possible to prevent foreign matter or the like from being pushed into the nozzle, or liquid from flowing out of the nozzle unnecessarily.

  A maintenance method for solving the above-described problem is a maintenance method for wiping a region including a nozzle opening in an ejection head in which a plurality of nozzles capable of ejecting liquid are opened, and determines whether the nozzle is in a good state or a defective state. Detecting each nozzle, increasing the pressure of the liquid in the nozzle so that the liquid level bulges from the nozzle opening, and increasing the internal pressure with respect to the defective nozzle detected as defective Wiping the area where the plurality of nozzles including the nozzles are opened.

  According to this configuration, it is possible to obtain the same effect as that of the liquid ejecting apparatus.

FIG. 3 is a cross-sectional view schematically illustrating an embodiment of a liquid ejecting apparatus. FIG. 2 is a cross-sectional view of a pressure adjustment mechanism and an ejection head of the liquid ejecting apparatus illustrated in FIG. 1. Explanatory drawing of the 1st pressure | voltage rise operation | movement of the liquid ejecting apparatus shown in FIG. Explanatory drawing of the 2nd pressure | voltage rise operation | movement of the liquid ejecting apparatus shown in FIG. FIG. 2 is a block diagram illustrating an electrical configuration of the liquid ejecting apparatus illustrated in FIG. 1. FIG. 3 is a flowchart showing a processing routine for boosting wiping performed by the liquid ejecting apparatus of FIG. 1. Sectional drawing which shows the example of a change of the pressure adjustment mechanism shown in FIG. FIG. 8 is a cross-sectional view taken along line 8-8 in FIG. 7. The top view which shows the 1st example of a change of the pressure receiving plate with which the pressure adjustment mechanism of FIG. 2 is provided. Sectional drawing which shows the effect | action of the pressure receiving plate of FIG. The top view which shows the 2nd modification of the pressure receiving plate with which the pressure adjustment mechanism of FIG. 2 is provided. Sectional drawing explaining an effect | action of the seal | sticker part with which the pressure adjustment mechanism of FIG. 2 is provided. The graph explaining the effect | action of the seal part of FIG. FIG. 3 is a cross-sectional view illustrating a modification example of a liquid supply mechanism included in the liquid ejecting apparatus of FIG. 1.

Hereinafter, an embodiment of a liquid ejecting apparatus will be described with reference to the drawings.
As shown in FIG. 1, the liquid ejecting apparatus 11 includes an ejecting head 13 in which a plurality of nozzles 12 capable of ejecting liquid are opened, and a supply for supplying pressurized liquid from the liquid supply source 14 toward the ejecting head 13. A mechanism 15, a pressure adjustment mechanism 16 that adjusts the pressure of the liquid supplied to the ejection head 13, a maintenance device 41, and a control unit 100 that controls these components are provided. The supply mechanism 15 and the pressure adjustment mechanism 16 constitute a liquid supply mechanism that supplies liquid to the ejection head 13.

  The liquid ejecting apparatus 11 according to the present embodiment is an ink jet printer that performs recording (printing) by ejecting ink, which is an example of liquid, from a ejecting head 13 onto a medium S such as paper that is transported in the transport direction. is there. The liquid ejecting apparatus 11 includes a line head 17 including a plurality of ejecting heads 13 arranged in parallel so that the printing range covers the entire width of the medium S as a component. The line head 17 has a liquid supply path 18 for supplying a liquid to the ejection head 13. The pressure adjustment mechanism 16 is provided in the middle of the liquid supply path 18.

  The liquid supply source 14 is, for example, a liquid storage bag stored in the storage container 21. The liquid supply source 14 is composed of a flexible bag, and contains liquid therein. A plurality of liquid supply sources 14 and storage containers 21 can be provided for each type of liquid (ink color in this embodiment). The supply mechanism 15 includes a liquid lead-out path 22 that communicates with the liquid supply source 14, a sub-tank 26 that is provided in the liquid lead-out path 22, a gas delivery path 23 that communicates with the internal space of the storage container 21, and a gas delivery path 23. And a delivery pump 25 that delivers gas (for example, air) to the internal space of the container 21 through the gas delivery path 23.

  When the gas is delivered through the gas delivery path 23 by driving the delivery pump 25, the gas enters the accommodation container 21 and the pressure in the accommodation container 21 increases. Then, the bag which comprises the liquid supply source 14 is compressed, and the liquid accommodated in the bag flows out into the liquid outlet path 22 in a pressurized state. The delivery pump 25 is driven at any time as the pressure of the liquid outlet path 22 decreases so that the liquid in the liquid outlet path 22 is maintained at a predetermined positive pressure.

  When there are a plurality of ejection heads 13, the liquid outlet path 22 branches into a plurality downstream from the sub-tank 26, and the liquid supply path provided in the line head 17 so that the branched downstream end corresponds to each ejection head 13. 18 is connected. The liquid supply path 18 and the pressure adjustment mechanism 16 are provided for each type of liquid in each ejection head 13.

  For example, when the liquids of the four liquid supply sources 14 are respectively supplied to the four ejecting heads 13, the four ejecting heads 13 are provided with four pressure adjusting mechanisms 16 for each liquid type. It is preferable to provide a filter 27 for filtering the liquid upstream of the pressure adjusting mechanism 16 in the liquid supply path 18.

  The ejection head 13 includes a common liquid chamber 31 in which the liquid supplied through the liquid supply path 18 provided for each type of liquid is temporarily stored, and a plurality of cavities provided to individually correspond to the plurality of nozzles 12. 32 and a plurality of actuators 33 provided so as to correspond to the respective cavities 32.

  Here, when the ejection head 13 ejects a plurality of types of liquids, the ejection head 13 has a plurality of nozzle groups N each including a plurality of nozzles 12 that eject one liquid. The nozzle group N refers to a group of nozzles 12 to which liquid is supplied from one common liquid chamber 31. The nozzle openings 12 a of the nozzle group N that ejects one liquid in the width direction of the medium S (the row direction that is the direction in which the ejection heads 13 are arranged) are arranged on the opening surface 13 a of the ejection head 13. Further, a plurality of (for example, four) nozzle openings 12 a that eject different liquids in the transport direction of the medium S that intersects the width direction (the direction orthogonal to the paper surface in FIG. 1) are formed on the opening surface 13 a of the ejection head 13. Lined up.

  Next, the maintenance operation of the ejection head 13 executed in the liquid ejection apparatus 11 and the maintenance apparatus 41 configured to perform maintenance of the ejection head 13 will be described.

  In the liquid ejecting apparatus 11, flushing, capping, suction cleaning, and cleaning are performed under the control of the control unit 100 in order to prevent or eliminate ejection failure caused by clogging of the nozzle 12 or adhesion of foreign matter in the ejection head 13. Perform maintenance operations such as wiping. The maintenance device 41 includes a cap 42 configured to perform capping, a suction mechanism 43 configured to perform suction cleaning using the cap 42, and a wiping unit 44 configured to perform wiping. Prepare.

  Flushing is forcibly ejecting (discharging) droplets from the nozzles 12 regardless of printing, thereby increasing the viscosity due to evaporation of foreign matter, bubbles, or altered liquid (for example, evaporation of solvent components) that causes ejection failure. Ink) is discharged. The liquid discharged as waste liquid by flushing may be received by the cap 42, or a flushing box for receiving waste liquid generated by flushing may be separately provided. The cap 42 may be provided for each ejection head 13 or may be provided for each ejection head 13 for each nozzle group N (for each type of liquid).

  The cap 42 and the ejection head 13 are relatively moved by a mechanism (not shown) between a capping position that surrounds and forms a space in which the nozzle 12 opens as a closed space and a separated position in which the space in which the nozzle 12 opens is an open space. Configured to do. Then, capping is performed by arranging the cap 42 at the capping position. When the liquid is not ejected, capping is performed to prevent the nozzle 12 from drying, thereby preventing ejection failure. Further, when the waste liquid generated by the flushing is received, the cap 42 is disposed at the separated position.

  The suction mechanism 43 includes a suction tube 45 whose upstream end is connected to the cap 42, a waste liquid storage portion 46 into which the downstream end of the suction tube 45 is introduced, a suction pump 47 provided in the middle of the suction tube 45, The suction tube 45 includes a pressure reducing valve 48 provided between the suction pump 47 and the cap 42. When a negative pressure generated by driving the suction pump 47 is applied to a closed space formed by placing the cap 42 at the capping position, suction cleaning is performed in which liquid is sucked and discharged from the nozzle 12 by the negative pressure. The The liquid discharged from the nozzle 12 by the suction cleaning is stored in the waste liquid storage unit 46 as a waste liquid. Note that the cap 42 also functions as a part of the suction mechanism 43 when performing the suction cleaning.

  The wiping unit 44 includes a wiping member 51 that wipes the opening surface 13a of the ejection head 13, a holding portion 52 that holds the wiping member 51, a guide shaft 53 that guides the movement of the holding portion 52 along the opening surface 13a, and a holding member. And a drive source 54 for moving the portion 52 along the opening surface 13a.

  The wiping member 51 is composed of an absorbing member such as a plate member made of an elastically deformable resin or a cloth that can absorb liquid. When the drive source 54 is driven, the wiping member 51 moves together with the holding portion 52 in a state where the wiping member 51 is in contact with the ejection head 13 with a predetermined contact pressure. Accordingly, wiping is performed in which the wiping member 51 wipes the ejection head 13 around the opening surface 13a. The wiping member 51 sequentially wipes the opening surfaces 13a of the plurality of ejection heads 13 while moving in the width direction of the medium S.

  At the start of use of the liquid ejecting apparatus 11, first, the liquid from the liquid outlet path 22 to the nozzle 12 is obtained by performing suction cleaning after the gas delivery path 23 is set to a positive pressure by driving the delivery pump 25. Fill the flowing area with liquid. This is called initial filling. Then, after the initial filling is performed, wiping is performed to wipe off the liquid adhering to the opening surface 13a, and further flushing is performed to prepare the meniscus M. Thus, it is preferable to sequentially perform wiping and flushing after suction cleaning.

Next, the detailed configuration of the ejection head 13 will be described.
As shown in FIG. 2, the actuator 33 includes, for example, a piezoelectric element 33a, and the wall of the cavity 32 in contact with the piezoelectric element 33a is a vibrating wall 32a that can be flexed and displaced in a direction to increase or decrease the internal volume of the cavity 32. .

  When the piezoelectric element 33a is contracted and deformed by energization, the vibration wall 32a of the cavity 32 is flexed and displaced in the direction of expanding the internal volume of the cavity 32 as shown by a two-dot chain line in FIG. When the internal volume of the cavity 32 is increased, the liquid stored in the common liquid chamber 31 is introduced into the cavity 32. Thereafter, when energization is stopped, the vibration wall 32a of the cavity 32 in contact with the piezoelectric element 33a is reduced in the direction in which the inner volume of the cavity 32 is reduced as shown by the one-dot chain line in FIG. Deflection is displaced. Then, the internal volume rapidly decreases, so that the liquid in the cavity 32 is pushed into the nozzle 12 and the pushed liquid is ejected from the nozzle 12 as droplets.

  In the ejection head 13, a region where the nozzle 12 opens is referred to as an opening surface 13a. Capillary force acts on the nozzle 12 which is a thin tubular hole, and the nozzle opening 12a which is the downstream side opening of the opening surface 13a of the nozzle 12 in a state where the actuator 33 is not driven has a liquid surface which is concave inward. A meniscus M is formed. After the liquid is ejected, the nozzle 12 is replenished with liquid corresponding to the ejected droplets from the cavity 32 on the upstream side by capillary force. In addition, the vibration wall 32a damps and vibrates after the drive voltage is applied to the piezoelectric element 33a and before the next drive voltage is applied.

In the liquid ejecting apparatus 11, the actuator 33 functions as a detection unit that can detect for each nozzle 12 whether the state of the nozzle 12 is good or defective.
Here, typical causes of the ejection failure of the nozzle 12 include mixing of bubbles, a decrease in fluidity of the liquid, and adhesion of foreign matter in the vicinity of the nozzle opening 12a. When the bubbles are mixed in the nozzle 12, the frequency of the residual vibration of the vibration wall 32a is compared with the case where the bubbles are not mixed in the nozzle 12 (when the state of the nozzle 12 is good). Tend to be higher.

  Moreover, when the fluidity | liquidity of the liquid is falling in the nozzle 12 (it is thickening), compared with the case where the liquid is not thickening in the nozzle 12 (when the state of the nozzle 12 is favorable). Thus, the frequency of residual vibration of the vibration wall 32a tends to be low. Furthermore, when the liquid or foreign matter adhering to the vicinity of the nozzle opening 12a is solidified, the frequency of the residual vibration of the vibration wall 32a tends to be an intermediate frequency between the time of bubble mixing and the time of thickening.

  For this reason, the actuator 12 functions as a sensor that obtains a voltage from the displacement of the vibration wall 32a, and the nozzle 12 having a poor nozzle 12 state is detected by detecting the frequency associated with the residual vibration of the vibration wall 32a accompanying the driving of the piezoelectric element 33a. That is, it becomes possible to detect a defective nozzle. The detection of whether the state of the nozzle 12 is good or defective by the actuator 33 is also referred to as “nozzle check”.

  In addition, as one of the maintenance operations of the ejection head 13, by driving the actuator 33, a voltage lower than that at the time of liquid ejection is applied to the piezoelectric element 33a at a predetermined interval so that the liquid is not ejected from the nozzle 12. It is also possible to execute “fine vibration” that vibrates 32a. By performing fine vibration, when the liquid is not ejected, the meniscus M in the nozzle 12 is vibrated in small increments to suppress the thickening of the liquid (ink), resulting in the thickening of the liquid. Occurrence of injection failure is suppressed.

Next, the configuration of the pressure adjustment mechanism 16 will be described in detail.
The pressure adjustment mechanism 16 is provided in the middle of the liquid supply path 18 communicating with the common liquid chamber 31, and can adjust the pressure of the liquid in the nozzle 12 for each nozzle group N.

  The pressure adjusting mechanism 16 includes a pressure chamber 62, a supply chamber 63, a valve body 64, and a valve body 64 in the supply chamber 63. And a second urging member 66 that urges the movable wall 61 toward the outside of the pressure chamber 62 in the pressure chamber 62.

  The pressure chamber 62 has an inflow hole 67 for allowing the liquid to be supplied under pressure to flow into a position different from the movable wall 61, and an outflow hole 68 communicating with the nozzle 12 (nozzle group N) via the common liquid chamber 31. Have. The supply chamber 63 can communicate with the pressure chamber 62 via the inflow hole 67. The valve body 64 has a proximal end portion disposed in the supply chamber 63 and a distal end portion protruding into the pressure chamber 62 through the inflow hole 67. The valve body 64 has a closed position (position shown in FIG. 2) where the seal portion 64a provided at the base end closes the inflow hole 67 and an open position (position shown in FIG. 4) where the inflow hole 67 is opened. The first urging member 65 accommodated in the supply chamber 63 is urged toward the closed position in a displaceable state. Further, the second urging member 66 has one end in contact with the pressure receiving plate 69 attached to the movable wall 61 and the other end disposed so as to surround the distal end portion of the valve body 64 protruding into the pressure chamber 62.

  The pressure adjustment mechanism 16 has a valve opening mechanism 71 that moves the valve body 64 toward the open position by being driven at a predetermined timing. The valve opening mechanism 71 includes, for example, a pressing member 72 disposed outside the pressure chamber 62 and a third urging member for urging the movable wall 61 toward the inside of the pressure chamber 62 via the pressing member 72. 73. In this case, the urging directions of the first urging member 65 and the second urging member 66 and the urging direction of the third urging member 73 are set in directions in which the urging forces cancel each other. For example, when the urging members 65, 66, and 73 are coil springs, the axial directions of the coil springs may be matched.

  The valve body 64 of the pressure adjusting mechanism 16 is urged by the first urging member 65 accommodated in the supply chamber 63 so that it does not move to the open position even if the pressure in the supply chamber 63 rises. On the other hand, when the pressure in the pressure chamber 62 becomes lower than a predetermined negative pressure due to the outflow of the liquid from the outflow hole 68, the movable wall 61 is displaced toward the inside of the pressure chamber 62, and the pressure receiving plate 69 is moved to the valve body 64. By pushing the tip, the valve body 64 moves to the open position. As a result, the pressurized liquid in the supply chamber 63 flows into the pressure chamber 62 through the inflow hole 67, so that the pressure in the pressure chamber 62 increases.

  When the movable wall 61 is displaced toward the outside of the pressure chamber 62 due to the pressure increase in the pressure chamber 62 and the pressure receiving plate 69 is separated from the tip of the valve body 64, the valve body 64 moves from the open position to the closed position. . Here, the second biasing member 66 pushes back the pressure receiving plate 69 in a direction away from the tip of the valve body 64 when the pressure receiving plate 69 approaches the tip of the valve body 64.

  Therefore, when the pressure in the pressure chamber 62 decreases and the pressure receiving plate 69 presses the tip of the valve body 64 against the urging force of the first urging member 65 and the second urging member 66, the valve body 64 is Move to the open position. Further, the pressure receiving plate 69 is separated from the valve body 64 by the urging force of the second urging member 66 before the pressure in the pressure chamber 62 rises to a positive pressure due to the inflow of the liquid, so the pressure in the pressure chamber 62 is The second pressure member 66 is held in a negative pressure range corresponding to the biasing force of the second biasing member 66.

  Thus, the movement of the valve body 64 to the open position occurs due to the displacement of the movable wall 61. The outer surface side of the movable wall 61 is open to the atmosphere. Therefore, the movement of the valve body 64 to the open position is performed without using a driving force of a motor or the like due to the differential pressure between the atmospheric pressure and the pressure chamber 62. The portion to be excluded is also referred to as a differential pressure valve mechanism 70 (or a self-sealing valve), and the autonomous pressure adjustment function by the differential pressure valve mechanism 70 is also referred to as a self-sealing function. Further, the negative pressure maintained in the region from the pressure chamber 62 to the nozzle 12 by this self-sealing function is referred to as the pressure during liquid ejection.

  As described above, the pressure adjusting mechanism 16 can regulate the flow of the liquid pressure-supplied by the supply mechanism 15 to the ejection head 13 and can reduce the pressure of the liquid on the downstream side where the flow is regulated to a predetermined negative value. The pressure can be maintained within a range.

  In other words, in the pressure adjustment mechanism 16, when the liquid is ejected, the liquid flows out from the outflow hole 68, and the internal volume of the pressure chamber 62 is decreased as the pressure in the pressure chamber 62 falls below a negative threshold value. The movable wall 61 displaced in the direction moves the valve body 64 to the valve opening position against the urging force of the urging members 66 and 65. Thereby, the pressurized liquid flows in from the inflow hole 67 and the pressure in the pressure chamber 62 increases. Further, when the pressure of the pressure chamber 62 becomes equal to or higher than a predetermined negative pressure threshold due to the supply of the pressurized liquid, the valve body 64 restricts the flow of the liquid from the upstream side again.

  When an external force is applied to the ejection head 13, the meniscus M formed on the nozzle 12 may be broken by the impact, and the liquid may leak from the nozzle 12. In order to suppress such leakage of the liquid, the pressure adjusting mechanism 16 holds the inside of the pressure chamber 62 located upstream of the nozzle 12 at a predetermined negative pressure by the urging force of the second urging member 66, The pressure resistance of the formed meniscus M is increased.

  That is, by performing flushing and reducing the pressure in the pressure chamber 62 after the suction cleaning, the meniscus M is drawn into the inner side of the nozzle 12 than in the case where the pressure chamber 62 is at atmospheric pressure. . Further, by increasing the pressure resistance of the meniscus M in this way, the reactivity of the meniscus M when the actuator 33 is driven is improved, so that it is possible to maintain the injection characteristics well.

  In addition to the self-sealing function described above, the pressure adjustment mechanism 16 forcibly sets the liquid pressure in the nozzle 12 by driving the valve opening mechanism 71 regardless of whether or not the liquid is discharged from the nozzle 12. (Step 2 in this embodiment) is provided with a forced boosting function. That is, the valve opening mechanism 71 is configured to increase the pressure of the liquid in the nozzle 12 so that the liquid level swells from the nozzle opening 12a by the urging force of the third urging member 73, and the first pressure increasing operation. A second pressure increasing operation in which the degree of pressure rise is smaller than the operation is performed.

  In the second pressure increasing operation, as shown in FIG. 3, the valve opening mechanism 71 moves the pressing member 72 and the third urging member 73 in a direction approaching the movable wall 61, and the urging force of the third urging member 73 is used. The movable wall 61 is pressed from the outside. At this time, if the urging force of the third urging member 73 is applied to the extent that the seal portion 64a of the valve body 64 is not separated from the inflow hole 67, the internal volume of the pressure chamber 62 is reduced by the displacement of the movable wall 61. The pressure of the liquid in the pressure chamber 62 and the nozzle 12 downstream thereof increases. The pressure rise at this time is such that the meniscus M is closer to the nozzle opening 12a than the curved position due to the pressure at the time of liquid injection indicated by a two-dot chain line, but does not bulge out beyond the nozzle opening 12a (second line indicated by a solid line). It is preferable to move to the boosting position.

  When the urging forces of the first urging member 65, the second urging member 66, and the third urging member 73 are F1, F2, and F3, respectively, if F1> F2 + F3, the pressure is received by the pressing of the pressing member 72. Even if the plate 69 contacts the valve body 64, it is possible to keep the valve body 64 in the closed position. Further, in this case, by setting F2 = F3, the pressure in the nozzle 12 can be raised from the pressure state at the time of liquid ejection without increasing the pressure in the nozzle 12 from atmospheric pressure. Swelling outside the nozzle opening 12a is suppressed. Note that F3 is a force that increases the pressure of the liquid in the nozzle 12, and may be referred to as a pressurizing force.

  In the first pressure increasing operation, as shown in FIG. 4, the valve opening mechanism 71 moves the pressing member 72 and the third urging member 73 in the same direction as the second pressure increasing operation, and moves the movable wall 61 to the outside only for a predetermined time. After the valve body 64 is moved to the open position by pressing the valve body 64, the valve body 64 is quickly returned to the original closed position. As a result, the pressurized liquid flows into the pressure chamber 62 by a predetermined amount, and the pressure of the liquid in the nozzle 12 increases. The pressure increase (amount of liquid to be introduced) at this time is preferably such that the meniscus M bulges outside the nozzle opening 12 a but does not drop from the nozzle 12.

Next, the electrical configuration of the liquid ejecting apparatus 11 will be described.
As illustrated in FIG. 5, the control unit 100 included in the liquid ejecting apparatus 11 controls the driving of the actuator 33, the delivery pump 25, and the pressure adjustment valve 24 to execute a liquid ejecting operation (printing operation). In addition, the control unit 100 controls the driving of the suction pump 47 and the pressure reducing valve 48 to execute suction cleaning. In addition, the control unit 100 controls the drive of the drive source 54 to move the wiping member 51 to execute wiping. In addition, the control unit 100 controls the driving of the actuator 33 to execute flushing. In addition, the control unit 100 detects the defective nozzle in which the ejection failure has occurred by causing the actuator 33 to function as the detection unit.

  Next, boosting wiping performed by increasing the pressure of the liquid in the nozzle 12 as a maintenance method for wiping the area including the nozzle opening 12a in the ejection head 13 in which the plurality of nozzles 12 capable of ejecting liquid are opened will be described. To do. The step-up wiping can be executed, for example, when printing on the medium S is completed, or every time a predetermined number of times or a predetermined number of sheets are printed.

In the pressure wiping, the controller 100 executes a processing routine shown in FIG. 6 when wiping.
That is, as shown in FIG. 6, the control unit 100 causes the actuator 33, which is a detection unit, to execute a nozzle check for all the nozzles 12 of the ejection head 13 prior to wiping (step S11). The nozzle check may be performed during printing, or may be performed while ejecting liquid regardless of printing, or the vibrating wall 32a is vibrated to such an extent that liquid is not ejected, as in flushing. You may do by letting.

  Subsequently, the control unit 100 determines whether there is a defective nozzle in the checked nozzle 12 from the value of the residual vibration frequency of the vibration wall 32a obtained by the nozzle check (step S12). That is, it is detected for each nozzle 12 whether the state of the nozzle 12 is good or bad (detection step).

  When there is a defective nozzle (step S12: YES), the control unit 100 causes the corresponding valve opening mechanism 71 to perform the first pressure increasing operation on the defective nozzle group including the defective nozzle, and includes the defective nozzle. For the normal nozzle group not present, the corresponding valve opening mechanism 71 is caused to execute the second pressure increasing operation (step S13). That is, in the detection step, the pressure of the liquid in the nozzle 12 is increased so that the liquid level swells from the nozzle opening 12a with respect to the defective nozzle detected as defective (pressure increase step). On the other hand, when there is no defective nozzle (step S12: NO), the control unit 100 causes the corresponding valve opening mechanism 71 to execute the second pressure increasing operation for all nozzle groups (step S14).

  Then, following step S13 or step S14, the control unit 100 controls the drive of the drive source 54 and moves the wiping member 51 to cause wiping (step S15). That is, the area | region (opening surface 13a) which the some nozzle 12 to which the internal pressure rose opens is wiped off (wiping process).

  Although wiping is performed after printing, the nozzle check may be performed during printing. When a nozzle check is performed during printing to detect a defective nozzle, wiping is not performed until printing on the medium S is completed, and the droplets to be ejected from the defective nozzle are supplemented with droplets ejected from the normal nozzle 12. It is preferable to perform complementary printing (interpolation printing).

  For example, when ejection failure occurs in one of the plurality of nozzles 12 that eject the same type (color) of liquid (ink), the normal nozzle 12 near the defective nozzle is changed to the defective nozzle. By ejecting a droplet larger than the droplet to be ejected, the missing dot is complemented. Alternatively, when an ejection failure occurs in the nozzle 12 that ejects the black ink, the yellow, cyan, and magenta droplets are repeatedly struck at the position where the droplets that are to be ejected from the defective nozzle land. Compensate for missing ink dots.

Next, the operation of the liquid ejecting apparatus 11 configured as described above and the maintenance method will be described.
In the liquid ejecting apparatus 11, when wiping with pressure wiping, the control unit 100 detects whether the state of the nozzle 12 is good or defective for each nozzle 12 by causing the actuator 33 to function as a detection unit. When a defective nozzle is detected, the corresponding valve opening mechanism 71 is caused to execute the first pressure increasing operation for the defective nozzle group including the defective nozzle, and for the normal nozzle group not including the defective nozzle. Thus, wiping is executed in a state where the corresponding valve opening mechanism 71 is caused to execute the second pressure increasing operation.

  As a result, the meniscus M in the defective nozzle group is swollen from the nozzle opening 12a by the first pressure increasing operation, while the meniscus M is moved to a position close to the nozzle opening 12a in the normal nozzle group by the second pressure increasing operation. Thus, wiping is performed.

  That is, at the time of wiping, the valve opening mechanism 71 moves the valve body 64 to the open position against the urging force of the urging members 66 and 65, so that the pressurized liquid flows from the inflow hole 67, The pressure in all the nozzles 12 of the defective nozzle group including the pressure chamber 62 and the defective nozzle is increased.

  As a result, in the defective nozzle group, as shown in FIG. 4, the wiping member 51 comes into contact with the liquid surface (meniscus M) swelled from the nozzle opening 12 a when the inside of the nozzle 12 is in a pressurized state (positive pressure). Then, since the pressurized liquid flows out from the nozzle opening 12a through the wiping member 51, the bubble or the thickened liquid that causes the nozzle 12 to be poorly ejected is discharged or attached to the opening surface 13a. The attached deposits are washed away.

  Further, by performing wiping while wetting the wiping member 51 and the opening surface 13a with the liquid flowing out from the nozzle 12, the foreign matter adhering to the opening surface 13a can be dissolved in the liquid and effectively removed. Furthermore, if the foreign material adhering to the opening surface 13a is dragged in a state where the wiping member 51 is dry, the opening surface 13a may be damaged. However, by wetting the opening surface 13a with the liquid flowing out from the nozzle 12, the opening surface 13a The damage of 13a is suppressed.

  At this time, the pressure in the nozzles 12 of the defective nozzle group is positive due to the first pressure increase operation, but since the valve body 64 has returned to the closed position, the liquid introduced into the pressure chamber 62 by the first pressure increase operation. No more liquid will escape. Therefore, wasteful consumption of liquid due to boosting wiping is suppressed.

  On the other hand, in the normal nozzle group, as shown in FIG. 3, although the pressure inside the nozzle 12 is slightly increased as compared with the time of liquid injection, there is a liquid surface (meniscus M) inside the nozzle opening 12a. The wiping member 51 is unlikely to come into contact with the liquid level with wiping. Therefore, since the liquid does not easily flow out when the wiping member 51 comes into contact with the liquid surface, wasteful consumption of the liquid due to wiping is suppressed.

  Further, when wiping is performed when the inside of the nozzle 12 is at the same negative pressure as that during the liquid injection, the wiping member 51 pushes the air between the concave meniscus M and the nozzle opening 12a into the nozzle 12, and the nozzle 12 There is a possibility that bubbles may be generated inside. That is, when some of the plurality of nozzles 12 are defective nozzles, the wiping for some defective nozzles is performed even though it is not always necessary to wipe the normal nozzles 12. On the contrary, there is a possibility that an ejection failure may occur in the normal nozzle 12.

  In that respect, if the pressure in the nozzle 12 is set to a value close to the atmospheric pressure by the second pressure increasing operation, the air is almost eliminated between the meniscus M and the nozzle opening 12a. Air bubbles are less likely to be generated in the inside. That is, it is possible to perform maintenance of defective nozzles and the opening surface 13a while reducing adverse effects on normal nozzles.

  Further, when no defective nozzle is detected by the nozzle check, the nozzle 12 does not have an ejection failure, but the fine mist generated by the liquid ejection adheres to the opening surface 13a. It is preferable to wipe 13a. In this case, the control unit 100 causes the pressure adjustment mechanism 16 (the valve opening mechanism 71) to execute the second pressure increasing operation, which is less than the first pressure increasing operation, for all the nozzle groups N. Thus, since the wiping member 51 performs wiping, the occurrence of defective injection due to the gas being pushed in and the wasteful consumption of liquid are suppressed.

  Note that a nozzle check may be performed to confirm whether or not the ejection failure has been resolved after the wiping is performed, and suction cleaning may be performed when a defective nozzle is detected. In addition, when the cap 42 is provided for each nozzle group N and suction cleaning for sucking the closed space where the nozzle 12 is open can be performed for each nozzle group N, the defective nozzle group in which the defective nozzle is detected after wiping is performed. Alternatively, suction cleaning may be selectively performed.

  That is, in the case where an ejection failure occurs due to the entry of minute bubbles from the nozzle opening 12a, the ejection failure is eliminated to the extent that the liquid in the nozzle 12 is discharged. However, when a large bubble is mixed in the liquid supply path 18 due to the attachment / detachment / replacement of the liquid supply source 14 which is an ink cartridge, the bubble extends from the common liquid chamber 31 to many nozzles 12 and many adjacent ones. The nozzles 12 may have injection failure at the same time. In such a case, since the ejection failure is not eliminated by wiping, the ejection failure is eliminated by performing suction cleaning in which more liquid flows from the liquid supply source 14 and the liquid in the ejection head 13 is replaced. To do.

  After the suction cleaning is performed, it is necessary to remove the droplets attached to the opening surface 13a. However, since the ejection failure of the nozzle 12 should be eliminated by the suction cleaning, the liquid is caused to flow out of the nozzle 12 by wiping. There is no need. Therefore, when the wiping is performed after the suction cleaning is performed, the control unit 100 performs the second pressure increasing operation with respect to all the nozzle groups N with the pressure increasing mechanism 16 ( It is preferable to cause the wiping member 51 to perform wiping in a state where the valve opening mechanism 71) is executed.

  In this case, the wiping is performed not only for the suction cleaning after wiping but also for removing the droplets adhering to the opening surface 13a after the suction cleaning accompanying the initial filling or after the suction cleaning performed alone. It is preferable to perform wiping in a state where the second pressure increasing operation is performed by the pressure adjusting mechanism 16 (the valve opening mechanism 71) for all the nozzle groups N.

  In addition, for the detected defective nozzle, no effect can be expected even if “fine vibration” is performed as a maintenance operation. In addition, moving the meniscus M in which an abnormality has occurred causes the introduction of bubbles. There is a fear. For this reason, it is preferable not to execute “fine vibration” for a defective nozzle until it returns to a normal state by a maintenance operation such as wiping or suction cleaning.

  Further, when the liquid is not ejected, the second pressure increasing operation by driving the valve opening mechanism 71 may be executed at a predetermined interval instead of the “fine vibration”. Thereby, the meniscus M in the nozzle 12 can be moved in small increments, so that it is possible to suppress the increase in the viscosity of the liquid (ink) and to prevent the occurrence of ejection failure due to the increase in the viscosity of the liquid.

According to the above embodiment, the following effects can be obtained.
(1) About the defective nozzle group, since wiping is performed in a state where the liquid level is expanded from the nozzle 12, the wiping member 51 is brought into contact with the liquid level expanded from the defective nozzle and is present in the nozzle 12. Foreign matter or the like that causes the ejection failure can be discharged together with the liquid, and the ejection failure can be appropriately eliminated. On the other hand, for the normal nozzle group, since the degree of pressure increase in the nozzle 12 is smaller than that of the defective nozzle group, the wiping member 51 is less likely to contact the liquid level, and even if the wiping member 51 is in contact with the liquid level, Since the outflow amount of liquid is smaller than that of the defective nozzle group, wasteful consumption of liquid is suppressed. When the pressure in the nozzle 12 is negative, the lower the pressure is, the more the liquid level is drawn into the nozzle 12, and the outflow of liquid due to the wiping member 51 coming into contact with the liquid level is suppressed. . However, the greater the degree of negative pressure in the nozzle 12 and the more the liquid level enters the nozzle 12, the easier it is to push foreign objects and bubbles around the wiping member 51 into the nozzle 12 as it passes through the nozzle opening 12a. On the contrary, there is a risk of inducing injection failure. In this regard, if the pressure of the liquid in the nozzle 12 is also increased for the normal nozzle group, it is possible to suppress the occurrence of injection failure due to the entry of foreign matter or the like into the nozzle 12.

  (2) The pressure in the nozzle 12 can be increased by forcibly moving the valve body that adjusts the pressure in the pressure chamber by moving with the consumption of the liquid by the valve opening mechanism 71. That is, since the valve opening mechanism 71 may be added to the pressure adjustment mechanism 16 for adjusting the pressure in the pressure chamber 62, a dedicated pressure adjustment mechanism (valve opening) is used to adjust the pressure in the nozzle 12 during wiping. Compared with the case where a mechanism) is provided, it is possible to prevent the configuration of the apparatus from becoming complicated.

  (3) Since the liquid adheres to the ejection head 13 after the suction cleaning for sucking the closed space where the nozzle 12 is opened, it is preferable to wipe off such liquid by the wiping member 51. However, when the suction cleaning is selectively performed on the defective nozzle group including the defective nozzle in which the ejection failure has occurred, the inside of the nozzle 12 remains negative with respect to the normal nozzle group N on which the suction cleaning is not performed. When wiping is performed, when the wiping member 51 passes through the nozzle opening 12a, there is a possibility that a foreign object or air bubble around the wiping member 51 will be pushed into the nozzle 12 to cause an ejection failure. Further, with respect to the nozzle group N that has been subjected to suction cleaning, foreign matter and the like in the nozzle 12 have already been discharged by suction, so there is no need to allow the liquid to flow out of the nozzle 12. In that respect, according to the above-described embodiment, when the ejection head 13 is wiped after the suction cleaning is performed, the pressure in the nozzle 12 is increased to the extent that the outflow of liquid is suppressed for all the nozzle groups N. Since the pressure adjusting mechanism 16 performs the pressure increasing operation, it is possible to prevent foreign matter or the like from being pushed into the nozzle 12 or liquid from flowing out of the nozzle 12 unnecessarily.

In addition, you may change the said embodiment like the example of a change shown below. Moreover, the said embodiment and each modification can be used in combination with each other.
<Modification example of pressure adjustment mechanism 16>
Instead of the pressure adjustment mechanism 16 that can adjust the pressure of the liquid in the nozzle 12 for each nozzle group N, a pressure adjustment mechanism that can adjust the pressure of the liquid in the nozzle 12 for each nozzle 12 is adopted, and the above pressure increase Wiping may be performed. For example, if the actuator 33 is caused to function as a pressure adjustment mechanism, the pressure of the liquid in the nozzle 12 can be adjusted for each nozzle 12. In this case, the pressure adjustment mechanism 16 may be a differential pressure valve mechanism 70 that does not include the valve opening mechanism 71. In this case, the control unit 100 causes the pressure adjustment mechanism (actuator 33) to increase the pressure of the liquid in the nozzle 12 relative to the defective nozzle detected as defective in the actuator 33 as the detection unit. If the one pressure increasing operation is executed, the liquid level can be expanded from the nozzle opening 12a of the defective nozzle.

  In the pressure increasing operation by the actuator 33, the movable wall 61 is bent and displaced in a direction to increase the internal volume of the cavity 32 in accordance with the energization of the piezoelectric element 33 a, and then the energization is stopped to make the movable wall 61 move to the internal volume of the cavity 32. This is done by bending and displacing in the direction of decreasing. At this time, by adjusting the energization amount to the piezoelectric element 33a, pressurization is performed so that droplets are not ejected from the nozzle 12 in the first boost operation, and the pressure increase is higher in the second boost operation than in the first boost operation. Reduce the degree. And the drive source 54 is controlled so that the wiping member 51 passes the position where each nozzle 12 opens at the timing when the pressure in the nozzle 12 rises and the meniscus M is displaced.

  According to this configuration, the defective nozzle detected as a defective detection unit is wiped in a state where the liquid level is expanded from the nozzle opening 12a due to the pressure increase in the nozzle 12, so that the wiping member 51 is defective. By contacting the liquid surface swollen from the nozzle, foreign matter or the like that exists in the nozzle 12 and causes the ejection failure can be discharged together with the liquid, and the ejection failure can be appropriately eliminated. At this time, since the pressure increasing operation for increasing the pressure in the nozzle 12 is performed on a defective nozzle, the wiping member 51 is unlikely to come into contact with the liquid surface of the normal nozzle 12, and the wiping member 51 is on the liquid surface. Even if it contacts, the outflow of a liquid is suppressed. Therefore, maintenance of the ejection head 13 having the nozzles 12 can be appropriately performed while suppressing wasteful consumption of liquid. Further, according to this configuration, it is not necessary to provide a dedicated pressure adjustment mechanism (valve opening mechanism 71) for performing the boost wiping, and therefore the boost wiping can be performed with a simple configuration.

<Modification example of valve opening mechanism 71>
As in the modification shown in FIG. 7, the valve opening mechanism 71 includes a liquid storage part 75 disposed downstream of the outflow hole 68, and a gas partitioned by the liquid storage part 75 and a flexible film 76 that can be deflected and displaced. Even if it changes into the structure provided with the storage chamber 77, the air supply path 78 for making the pressurized gas of the gas delivery path 23 flow in into the gas storage chamber 77, and the adjustment valve 79 provided in the air supply path 78. Good. In this case, when the pressurized gas (air) is sent to the gas storage chamber 77 through the air supply path 78 by opening the regulating valve 79, the flexible film 76 reduces the volume of the liquid storage portion 75. The pressure of the liquid in the liquid reservoir 75 and in the nozzle 12 downstream thereof is increased. According to this configuration, since the pressurized gas for pressurizing and supplying the liquid can be used as the driving force for performing the first boosting operation and the second boosting operation, the first boosting operation and the second boosting operation are possible. There is no need to provide a separate drive source for the operation.

In addition, as a mechanism for moving the pressing member 72 in the valve opening mechanism 71, any mechanism such as a cam or a piston can be adopted.
<Modification example of differential pressure valve mechanism 70>
As in the modification shown in FIG. 7, in the differential pressure valve mechanism 70, the second urging member 66 is disposed so as to constitute a part of the shaft portion 64 b inserted into the inflow hole 67 of the valve body 64. Also good. According to this configuration, the gap through which the liquid flows in the inflow hole 67 can be widened.

  As in the modified example shown in FIG. 7, in the differential pressure valve mechanism 70, a guide portion 63 a for guiding the movement of the valve body 64 may be provided in the supply chamber 63. When the supply chamber 63 is narrow, the valve body 64 may be moved using the inner wall of the supply chamber 63 as a guide portion. However, when the supply chamber 63 becomes wide, there arises a problem that the movement of the valve body 64 becomes unstable. . In that respect, if the guide part 63a is provided in the supply chamber 63, the movement of the valve body 64 can be stabilized by the guide part 63a while ensuring the storage amount of the liquid by increasing the internal volume of the supply chamber 63. . Further, by widening the supply chamber 63, it is possible to reduce the portion where the liquid flow is stagnated and to suppress sedimentation of contained components and retention of bubbles.

  In this case, as shown in FIG. 8, the guide portion 63 a is arranged around the valve body 64 and is arranged so as to have a predetermined gap in the circumferential direction so as not to hinder the flow of liquid as shown by an arrow. It is preferable. In addition, it is more preferable that the guide portion 63a is formed in a thin pin shape in that the liquid flow is not hindered. In addition, it is preferable to dispose the guide portions 63a around the valve body 64 at a predetermined interval because the liquid flow toward the inflow hole 67 can be dispersed.

<Modification example of pressure receiving plate 69>
As shown in FIG. 9, the pressure receiving plate 69 is provided with one or more through holes 69a in the vicinity of the center, and communicates with the through holes 69a on the surface attached to the movable wall 61 and extends to the outer peripheral edge. A groove 69b may be provided.

  According to this configuration, as indicated by an arrow in FIG. 10, the liquid flowing into the pressure chamber 62 from the supply chamber 63 through the inflow hole 67 flows into the through hole 69 a and the groove 69 b of the pressure receiving plate 69, thereby causing the pressure chamber 62. Liquid can be pumped into the corners or bottom of the.

  Here, since the liquid does not easily flow at the corner or the bottom of the pressure chamber 62, there is a problem that the mixed bubbles stay and grow into larger bubbles. And when the bubble which became large flows in into the nozzle 12, there exists a problem that an injection defect arises. Further, when the liquid contains a sedimentation substance such as a pigment, the sedimentation substance settles at the corner or bottom of the pressure chamber 62, and the liquid concentration changes or the fluidity is lowered to cause the ejection. There is a problem that the print quality deteriorates due to the occurrence of defects.

  In that respect, as in the above configuration, if the pressure receiving plate 69 is provided with the through hole 69a and the groove 69b and the liquid flows to the corner or the bottom of the pressure chamber 62, the liquid in the pressure chamber 62 is stirred and the pigment is stirred. It is preferable because sedimentation of the liquid and the like can be suppressed and liquid retention can be suppressed. Note that it is more preferable to set the direction of the pressure chamber 62 so that the pressure receiving plate 69 is positioned at the bottom of the pressure chamber 62, because the liquid stirring effect can be enhanced.

  -As shown in FIG. 11, the groove | channel 69b provided in the pressure receiving plate 69 can be changed into arbitrary shapes, such as providing in a spiral shape toward the outer periphery from the through-hole 69a. In addition, when the groove 69b is provided in a spiral shape, a spiral flow can be generated in the pressure chamber 62, so that the liquid stirring effect can be enhanced. Further, the number of through holes 69a and grooves 69b provided in the pressure receiving plate 69 can be arbitrarily changed.

  In the above embodiment, the second pressure increase operation may be repeated when liquid is not ejected in order to suppress sedimentation of pigment or the like and liquid retention. When the second pressure increasing operation is repeated in this manner, it is preferable to employ a pressure receiving plate 69 as shown in FIG. 9 or 10 because the liquid can be circulated efficiently in the pressure chamber 62. In addition, when the frequency that the valve body 64 moves to the open position with printing is high, or when the flow rate of the liquid flowing into the inflow hole 67 is large, the liquid using the pressure receiving plate 69 shown in FIG. Stirring is performed effectively.

<Modification example of seal part 64a>
The seal portion 64a provided at the base end portion of the valve body 64 is preferably made of an elastically deformable material, and may be made of, for example, an elastomer. In particular, the seal portion 64a is preferably composed of an elastic body whose elastic displacement increases with time, such as silicone rubber.

  That is, as shown in FIG. 12, when the valve body 64 moves to the closed position, the seal portion 64a contacts the outer peripheral portion of the upstream opening of the inflow hole 67 (referred to as the contact portion 63b). A liquid-containing component (for example, a pigment or the like) may adhere to and accumulate on the portion 63b as the valve body 64 opens and closes. When such deposits accumulate, when the valve body 64 moves to the valve closing position, a gap is generated between the seal portion 64a and the contact portion 63b, and liquid leaks from the supply chamber 63 into the inflow hole 67. Problem arises. If such a problem occurs, there is a possibility that the liquid cannot be properly ejected or the liquid leaks from the nozzle 12.

  Such a seal failure is caused by penetration of the liquid sandwiched in the minute space between the seal part 64a and the contact part 63b due to the presence of a minute cavity existing in the seal part 64a or the contact part 63b and an impurity element serving as a water absorption component. It is thought that this is caused by the fact that the liquid is compressed and dehydrated by the pressure principle, the liquid in the minute space is thickened, and the contents are aggregated.

  In addition, when the seal portion 64a is made of a styrene-based elastomer, the oil component mixed for hardness adjustment flows out or reacts with the liquid-containing component by receiving the urging force of the first urging member 65. As a result, alteration occurs and curing shrinkage gradually occurs. Then, when the seal portion 64a can no longer fill the step due to the accumulation of deposits generated between the seal portion 64a and the contact portion 63b, the above-described seal failure occurs. That is, if the deposit height is Hd and the step height at which the seal portion 64a is filled is Hs, it is considered that a seal failure occurs when Hd> Hs.

  Even when there is no cure shrinkage of the seal portion 64a, a seal failure occurs if the amount of deposits is large, and even if there is no deposit of deposits, the seal portions 64a and the contact portions If the seal portion 64a is cured and contracted when a foreign object is sandwiched between them, a seal failure may occur.

  In that respect, when the amount of elastic displacement increases with time like the seal part 64a made of silicone rubber, the height of the step where the seal part 64a is filled increases as time elapses after the start of use.

  That is, as shown in FIG. 13, if the height of the step where the silicone rubber seal portion 64a is filled is Hs1, and the height of the step where the styrene rubber seal portion 64a is filled is Hs2, the elapsed time T increases. Accordingly, Hs1 of the silicone rubber seal portion 64a increases, whereas Hs2 of the styrene rubber seal portion 64a decreases. As a result, L1 when Hd = Hs1 from the start of use (T = 0, Hd = 0) is later than L2 when Hd = Hs2. Therefore, when the amount of elastic displacement increases with time, such as the seal portion 64a made of silicone rubber, the adhering matter with time elapses, compared with the case where the amount of elastic displacement decreases with time, such as the case of styrene rubber. Even when the amount of the deposit increases, the sealing portion 64a is more elastically deformed, so that the sealing performance can be maintained better for a longer period of time.

  As shown in FIG. 12, in the structure in which the movement of the valve body 64 is guided by the inner wall of the supply chamber 63, the liquid hardly flows in the region Cn near the bottom side wall near the contact portion 63b. The dispersion state of the solid component is likely to be unstable. Therefore, even if the contained particles themselves are small, the particles are likely to change into large aggregates, and when such aggregates are sandwiched between the seal part 64a and the contact part 63b, a larger step is generated, Sealing performance may deteriorate.

  Therefore, for the seal portion 64a, in addition to using a material whose amount of elastic displacement increases with time, as shown in FIG. 7, a guide portion 63a is provided in the supply chamber 63 to widen the space surrounding the contact portion 63b. For example, an increase in sedimentation height of sedimentation components and aggregation of sedimentation components can be suppressed.

  As described above, the configuration of the differential pressure valve mechanism 70 including the seal portion 64a includes the usage frequency of the liquid ejecting apparatus 11, usage status (whether liquid consumption during printing such as painting is large), service life, usage environment (temperature). , Humidity, etc.) or the type of liquid used, etc.

<Change example of liquid supply mechanism>
As shown in FIG. 14, the liquid ejecting apparatus 11 includes a liquid supply mechanism 81 instead of the supply mechanism 15 for pressurizing and supplying the liquid to the ejection head 13 and the pressure adjusting mechanism 16 for adjusting the pressure. May be.

  The liquid supply mechanism 81 includes a sub tank 26 that is connected to the liquid supply source 14 through the liquid outlet path 22, a liquid storage chamber 82 that communicates with the ejection head 13 via the common liquid chamber 31, and the sub tank 26 and the liquid storage chamber 82. The liquid flow path 83 which connects one end side, and the return flow path 84 which connects the other end side of the liquid storage chamber 82 and the sub tank 26 are provided. The liquid supply mechanism 81 includes an on-off valve 85 provided in the liquid outlet path 22, a flow mechanism 86 provided in the liquid flow path 83, and a one-way valve 87 provided in the return flow path 84. The one-way valve 87 allows a liquid flow from the sub tank 26 to the liquid storage chamber 82, while suppressing a liquid flow from the liquid storage chamber 82 to the sub tank 26.

  A part of the wall surface of the sub tank 26 is configured by a flexible film 26 a that can be deflected and displaced, and the sub tank 26 is disposed below the liquid tank that is the liquid supply source 14 in the vertical direction. Therefore, when the on-off valve 85 is opened, the liquid flows from the liquid supply source 14 to the sub tank 26 through the liquid lead-out path 22 due to a water head difference between the liquid level in the liquid supply source 14 and the liquid level in the sub tank 26. Then, when the liquid is discharged by the liquid jet or the like in the jet head 13, the liquid is supplied from the liquid supply source 14 to the sub tank 26 based on the water head difference. When the liquid supply source 14 is disposed below the sub tank 26 in the vertical direction, a pump is provided in place of the on-off valve 85 so that the liquid is sent from the liquid supply source 14 to the sub tank 26 by driving the pump. It may be.

  The liquid storage chamber 82 is disposed below the sub tank 26 in the vertical direction. In the liquid storage chamber 82, when the liquid flow path 83 is connected to one end side and upward in the longitudinal direction of the liquid storage chamber 82, and the return flow path 84 is connected to the other end side and downward in the same longitudinal direction, the liquid storage chamber 82 It is preferable because the liquid can be flowed along the longitudinal direction and the vertical direction of 82 to suppress sedimentation of pigments and the retention of bubbles. In this modified example, the filter 28 for filtering the liquid is disposed between the liquid storage chamber 82 and the common liquid chamber 31.

  The flow mechanism 86, for example, causes the liquid to flow in the supply direction (direction indicated by the solid line arrow in FIG. 14) from the sub tank 26 to the liquid storage chamber 82 by performing the first drive (forward rotation drive), and the second This is a pump that causes the liquid to flow in a return direction (direction indicated by a two-dot chain line arrow in FIG. 14) from the liquid storage chamber 82 toward the sub tank 26 by driving (reverse driving).

  When the liquid supply mechanism 81 supplies liquid to the ejection head 13 for liquid ejection or suction cleaning, the liquid supply mechanism 81 stops driving the flow mechanism 86 and causes the liquid stored in the sub tank 26 to flow through the liquid flow path 83 and the return flow. The liquid is allowed to flow into the liquid storage chamber 82 through the path 84.

  Further, the liquid supply mechanism 81 performs the second drive of the flow mechanism 86 as the first pressure increasing operation and the second pressure increasing operation. At this time, due to the second driving of the flow mechanism 86, the liquid flows in the return direction toward the sub tank 26 in the liquid flow path 83, and the liquid flows toward the liquid storage chamber 82 in the return flow path 84. As a result of the liquid circulating in the chamber 82, the pressure of the liquid in the common liquid chamber 31 and the nozzle 12 downstream thereof increases. Note that the degree of the pressure increase can be adjusted by changing the driving force of the flow mechanism 86. And the above-mentioned pressure wiping can be performed by wiping in the state which raised the pressure in the nozzle 12 by circulation of the liquid.

  Further, when the printing operation is not performed, the second driving of the flow mechanism 86 is performed at a predetermined interval so that the applied pressure is approximately the same as that of the second pressure increasing operation, and the meniscus M is shaken to thereby generate the liquid (ink). It is possible to suppress the increase in viscosity and suppress the occurrence of ejection failure due to the increase in the viscosity of the liquid.

  Further, by circulating the liquid by the second driving of the flow mechanism 86, it is possible to suppress sedimentation of pigments and the like contained in the liquid, and to collect bubbles in the liquid storage chamber 82 and the like in the sub tank 26. If a part of the wall surface of the sub tank 26 is a flexible film 26a, the influence of pressure fluctuations accompanying the circulation of the liquid is reduced, and the destruction of the meniscus M and the leakage of the liquid from the nozzle 12 are suppressed. be able to. It should be noted that when the liquid is circulated for the purpose of sedimentation of pigments or recovery of bubbles, it is preferable not to displace the meniscus M of the nozzle 12. In this case, the pressure increasing operation for pressure wiping is performed. However, it is preferable to reduce the driving force of the flow mechanism 86 when the liquid is circulated.

  In addition, in the liquid supply mechanism 81, the flow mechanism 86 performs the first drive to perform pressure cleaning. That is, in the state where the flow toward the sub tank 26 in the return flow path 84 is suppressed by the one-way valve 87, the liquid flows from the sub tank 26 toward the liquid storage chamber 82 in the liquid flow path 83, whereby the common liquid chamber 31 and The liquid is discharged from the nozzle 12 through the cavity 32.

  According to such a liquid supply mechanism 81, by supplying the liquid to the liquid storage chamber 82 through both the liquid flow path 83 and the return flow path 84, the liquid is supplied to the liquid storage chamber 82 with only one flow path. The amount of liquid supplied to the ejection head 13 can be increased as compared with the case of supplying. Further, by circulating the liquid between the sub tank 26 and the liquid storage chamber 82, the pressure of the liquid in the nozzle 12 can be increased.

  In suction cleaning, there is a problem that by depressurizing the liquid, the gas dissolved in the liquid appears as bubbles, and bubbles are generated. The liquid can be discharged as a maintenance operation while suppressing the occurrence.

<Examples of changing the applied pressure during boosting operation>
When the urging forces of the first urging member 65, the second urging member 66, and the third urging member 73 are F1, F2, and F3, respectively, wiping is performed as F1 + F2 <F3 in the first step-up operation. In the step-up operation, wiping may be performed with F2 ≦ F3. Note that F3 is not necessarily limited to the urging force of the third urging member 73 (spring) but can be a pressing force as a pressing force by the pressing member 72, the cam or the piston.

  Alternatively, wiping may be performed as F2 <F3 <F1 + F2 in the first boosting operation, and wiping may be performed as F3 ≦ F2 in the second boosting operation. In this case, since the valve body 64 is held at the valve closing position by the pressure adjusting mechanism 16 located upstream of the nozzle 12 that is the target of the first pressure increasing operation, the wiping member 51 contacts the meniscus M. The amount of liquid discharged can be reduced.

Note that when setting the pressurizing force (F3) in the first boosting operation and the second boosting operation, it is preferable to consider the sealing performance of the seal portion 64a described above.
In addition, the degree of pressure increase (pressure applied) in the first pressure increasing operation or the second pressure increasing operation may be changed according to the type of liquid (the degree of surface tension of the liquid). This is because even if the pressure of the liquid in the nozzle 12 is constant, the position (curvature) of the meniscus M changes if the surface tension of the liquid is different.

Further, the degree of pressure increase may be changed in three or more stages depending on the cause of injection failure.
<Example of detection unit change>
The detection unit that can detect whether the state of the nozzle 12 is good or bad for each nozzle 12 may be changed to any configuration or method other than the actuator 33. For example, the state of each nozzle 12 may be detected by a camera (detection unit) that images the opening surface 13a, or a printed test pattern is optically read by a reading unit (detection unit) and based on the read image. A defective nozzle may be detected.

  Alternatively, in a state where a predetermined voltage is applied between the ejection head 13 and the cap 42 opposed to the ejection head 13, the voltage value of the applied voltage is changed when the liquid is ejected from the ejection head 13 to the cap 42. A defective nozzle may be detected based on this. In this case, the voltage detection unit that detects the voltage value of the voltage applied between the ejection head 13 and the cap 42 functions as a detection unit.

  ・ In addition to irradiating light rays so as to intersect with the flight trajectory of droplets ejected from the nozzle 12, the received light rays are received by a light receiving unit (detection unit) to detect the intensity change of the received light. Thus, the state of each nozzle 12 can also be detected. That is, if the light intensity at the light receiving portion changes by more than the threshold value, it is detected that the nozzle 12 is normal because the droplet is ejected normally.

<Other changes>
The liquid ejecting apparatus 11 is not limited to the one having the line head 17 in which the printing range extends over the entire width of the medium S, printing performed while the carriage holding the ejecting head 13 moves in the width direction of the medium S, A serial type that alternately performs conveyance in the conveyance direction intersecting the width direction may be used.

  The liquid ejected by the ejection head is not limited to ink, and 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.

  When the actuator 33 is not used as the detection unit, the actuator 33 is not limited to the one provided with the piezoelectric element (piezo element), the one provided with the electrostatic drive element, or the bubble generated by film boiling by heating the liquid It is also possible to change to a device including a heater element that discharges droplets from the nozzle 12 using the pressure (expansion pressure).

  The medium is not limited to paper, but may be a plastic film, a thin plate, or the like, or may be a fabric or clothing used for a printing apparatus.

  DESCRIPTION OF SYMBOLS 11 ... Liquid injection apparatus, 12 ... All nozzles, 12 ... Nozzle, 12a ... Nozzle opening, 13 ... Ejection head, 13a ... Opening surface, 14 ... Liquid supply source, 15 ... Supply mechanism, 16 ... Pressure adjustment mechanism, 17 ... Line Head, 18 ... liquid supply path, 21 ... storage container, 22 ... liquid outlet path, 23 ... gas delivery path, 24 ... pressure regulating valve, 25 ... delivery pump, 26 ... sub tank, 26a ... flexible membrane, 27 ... filter 31 ... Common liquid chamber, 32 ... Cavity, 32a ... Vibrating wall, 33 ... Actuator functioning as detection unit, 33a ... Piezoelectric element, 41 ... Maintenance device, 42 ... Cap, 43 ... Suction mechanism, 44 ... Wiping unit, 45 DESCRIPTION OF SYMBOLS ... Suction tube, 46 ... Waste liquid storage part, 47 ... Suction pump, 48 ... Pressure reducing valve, 51 ... Wiping member, 52 ... Holding part, 53 ... Guide shaft, 54 ... Drive source, 61 Movable wall, 62 ... pressure chamber, 63 ... supply chamber, 63a ... guide portion, 63b ... contact portion, 64 ... valve body, 64a ... seal portion, 64b ... shaft portion, 65 ... first biasing member, 66 ... first 2 urging members, 67 ... inflow hole, 68 ... outflow hole, 69 ... pressure receiving plate, 69a ... through hole, 69b ... groove, 70 ... differential pressure valve mechanism, 71 ... valve opening mechanism, 72 ... pressing member, 73 ... third Biasing member, 75 ... liquid storage section, 76 ... flexible membrane, 77 ... gas storage chamber, 78 ... air supply path, 79 ... regulating valve, 81 ... liquid supply mechanism, 82 ... liquid storage chamber, 83 ... liquid flow path , 84 ... Return flow path, 85 ... Open / close valve, 86 ... Flow mechanism, 87 ... One-way valve, 100 ... Control unit, M ... Meniscus, N ... Nozzle group, S ... Medium.

Claims (5)

An ejection head in which a plurality of nozzles capable of ejecting liquid are opened;
A wiping member for wiping an area including a nozzle opening of the ejection head;
A pressure adjusting mechanism capable of adjusting the pressure of the liquid in the nozzle for each nozzle;
A detection unit capable of detecting for each nozzle whether the state of the nozzle is good or bad;
For the defective nozzle detected as being defective by the detection unit, the pressure adjustment mechanism is caused to perform a pressure increasing operation for increasing the pressure of the liquid in the nozzle as compared with the time of liquid ejection, so that the liquid level is removed from the nozzle opening. A control unit that causes the wiping member to perform the wiping in a bulged state;
A liquid ejecting apparatus comprising: The ejection head has a plurality of nozzle groups composed of a plurality of the nozzles,
The pressure adjustment mechanism can adjust the pressure of the liquid in the nozzle for each nozzle group,
When the pressure increasing operation for increasing the pressure of the liquid in the nozzle so that the liquid level swells from the nozzle opening is the first pressure increasing operation,
The controller causes the pressure adjustment mechanism to perform the first pressure increasing operation on the defective nozzle group including the defective nozzle and performs the first pressure increase on the normal nozzle group not including the defective nozzle during the wiping. 2. The liquid ejecting apparatus according to claim 1, wherein the second pressure increasing operation is performed with a degree of pressure increase smaller than that of the pressure increasing operation. A supply mechanism for pressurizing and supplying liquid toward the ejection head;
The ejection head has a plurality of nozzle groups composed of a plurality of the nozzles,
The pressure adjusting mechanism is provided for each nozzle group, and has an inflow hole through which pressurized liquid is supplied and an outflow hole communicating with the nozzle group, and a movable wall that is displaceable in a direction to change the internal volume. A pressure chamber constituting a part of the wall surface, a valve body displaceable to a closed position for closing the inflow hole and an open position for opening the inflow hole, and urging the valve body toward the closed position An urging member, and a valve opening mechanism that moves the valve body toward the open position,
In the pressure adjustment mechanism,
When the liquid is ejected, the movable wall that is displaced in the direction of decreasing the internal volume of the pressure chamber as the liquid flows out from the outflow hole and the pressure in the pressure chamber decreases below a negative threshold value. By moving the valve body to the valve opening position against the urging force of the urging member, the pressurized liquid is introduced from the inflow hole to increase the pressure in the pressure chamber,
When the wiping is performed, the valve opening mechanism moves the valve body to the open position against the urging force of the urging member, thereby allowing the pressurized liquid to flow in from the inflow hole. The pressure in the nozzle is increased. The liquid ejecting apparatus according to claim 1, wherein the pressure in the nozzle is increased. When the ejection head has a plurality of nozzle groups composed of a plurality of the nozzles, and the pressure adjustment mechanism can adjust the pressure state in the nozzles for each nozzle group,
A suction mechanism capable of performing suction cleaning for sucking a closed space in which the nozzles are opened for each nozzle group;
When the pressure increasing operation for increasing the pressure of the liquid in the nozzle so that the liquid level swells from the nozzle opening is a first pressure increasing operation,
The controller is configured to cause the pressure adjustment mechanism to execute a second pressure increasing operation in which the degree of pressure increase is smaller than that of the first pressure increasing operation for all the nozzle groups after the suction cleaning is performed. The liquid ejecting apparatus according to any one of claims 1 to 3, wherein the wiping member performs the wiping. In a jet head in which a plurality of nozzles capable of jetting liquid are opened, a maintenance method for wiping a region including nozzle openings,
Detecting for each nozzle whether the state of the nozzle is good or bad;
Increasing the pressure of the liquid in the nozzle so that the liquid level bulges from the nozzle opening with respect to the defective nozzle detected as defective;
Wiping the area where the plurality of nozzles open, including the nozzle with increased internal pressure;
The maintenance method characterized by including.