JP6372206B2 - Liquid ejecting apparatus and maintenance method for liquid ejecting apparatus - Google Patents

Description

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

  Conventionally, as a kind of liquid ejecting apparatus, an ink jet printer that performs printing by ejecting ink from a nozzle of a recording head onto a medium such as paper has been known. In such a printer, when the nozzle of the inkjet head is clogged, so-called cleaning is performed in which the thickened ink or bubbles in the nozzle that cause clogging are sucked and removed.

  However, when ink that is particularly easy to solidify is used in the printer as described above, clogging of the nozzles may not be resolved even if the above-described cleaning is performed. Therefore, conventionally, an ink discharge device provided with a cleaning device (two-fluid ejection device) that dissolves and removes the ink solidified in the cleaning agent by discharging the cleaning agent to the nozzle formation region of the ink jet head (liquid ejecting unit). An apparatus (liquid ejecting apparatus) has been proposed (see, for example, Patent Document 1).

JP 2002-178529 A

  By the way, in the cleaning device of the ink discharge apparatus as in Patent Document 1, the ink solidified in the cleaning agent is dissolved and removed by discharging the cleaning agent to the nozzle formation region of the inkjet head. That is, the cleaning agent is ejected in the form of a mist and applied to the nozzle and the periphery of the nozzle, and the cleaning agent is soaked and dissolved in the solidified ink. For this reason, it takes time for the cleaning agent to reach the solidified ink in the nozzle, and there is a problem that it is difficult to effectively eliminate clogging of the nozzle.

  The present invention has been made paying attention to such problems existing in the prior art. An object of the present invention is to provide a liquid ejecting apparatus and a maintenance method for the liquid ejecting apparatus that can efficiently eliminate clogging of nozzles of the liquid ejecting section.

Hereinafter, means for solving the above-described problems and the effects thereof will be described.
A liquid ejecting apparatus that solves the above problem ejects at least one of a gas and a second liquid to a liquid ejecting unit capable of ejecting a first liquid from a nozzle opening to a medium, and the liquid ejecting unit. A two-fluid ejecting device capable of mixing the droplet-like second liquid containing droplets smaller than the opening of the nozzle of the liquid ejecting unit and the gas. Are ejected onto the liquid ejecting section including the nozzle.

  According to this configuration, the droplet of the second liquid in the mixed fluid smaller than the nozzle opening of the liquid ejecting unit enters the nozzle through the nozzle opening and collides with the clogged portion. It is possible to efficiently eliminate nozzle clogging.

  In the liquid ejecting apparatus, a product of a mass of the droplet of the second liquid smaller than the opening of the nozzle and a square of the flying speed of the droplet at the opening position of the nozzle is ejected from the opening of the nozzle. Preferably, it is larger than the product of the mass of the droplet of the first liquid and the square of the flying speed of the droplet.

  According to this configuration, the clogging in the nozzle, which cannot be eliminated even by the discharge operation of the first liquid droplet from the opening of the nozzle, is a motion at the time of the collision of the second liquid droplet to the clogged portion in the nozzle. It can be solved by energy.

  In the liquid ejecting apparatus, it is preferable that the two-fluid ejecting apparatus ejects the mixed fluid to the liquid ejecting section including the nozzle in a state where the first liquid in the liquid ejecting section is pressurized. .

According to this configuration, it is possible to suppress the mixed fluid that has been ejected to the liquid ejecting unit including the nozzle and entered into the nozzle from entering the back of the liquid ejecting unit.
In the liquid ejecting apparatus, the liquid ejecting unit includes a pressure chamber communicating with the inside of the nozzle and an actuator capable of pressurizing the pressure chamber, and the two-fluid ejecting apparatus is configured to drive the pressure by driving the actuator. It is preferable that the mixed fluid is ejected to the liquid ejecting unit including the nozzle in a state where the first liquid in the chamber is pressurized.

  According to this configuration, when the first liquid in the pressure chamber is pressurized by driving the actuator, the mixed fluid that has been ejected to the liquid ejecting portion including the nozzle and entered the nozzle is liquid via the pressure chamber. It becomes possible to suppress entering into the back in an injection part.

In the liquid ejecting apparatus, the second liquid is preferably pure water or a liquid containing a preservative in pure water.
According to this configuration, when the second liquid is pure water, the second liquid can be prevented from adversely affecting the first liquid when the second liquid is mixed with the first liquid in the nozzle. It becomes possible. Moreover, it is suppressed that the 2nd liquid rots by making the 2nd liquid into the liquid which contains the preservative in the pure water. For this reason, when the 2nd liquid is mixed with the 1st liquid in a nozzle, it becomes possible to control that the decayed component in the 2nd liquid has a bad influence on the 1st liquid.

  A maintenance method of a liquid ejecting apparatus that solves the above problem includes a liquid ejecting unit that can eject a first liquid from a nozzle opening to a medium, and at least one of a gas and a second liquid with respect to the liquid ejecting unit. A liquid ejecting apparatus maintenance method comprising: a two-fluid ejecting apparatus capable of ejecting one of the liquid ejecting apparatuses, wherein the liquid ejecting section including the nozzles has droplets smaller than an opening of the nozzle of the liquid ejecting section. After ejecting a mixed fluid obtained by mixing the droplet-like second liquid and the gas, the first liquid is discharged from the opening of the nozzle.

  According to this configuration, the droplet of the second liquid in the mixed fluid smaller than the nozzle opening of the liquid ejecting unit enters the nozzle through the nozzle opening and collides with the clogged portion. Nozzle clogging can be effectively eliminated. Since the first liquid is discharged from the opening of the nozzle after the clogging of the nozzle of the liquid ejecting section is eliminated, it is possible to discharge the mixed fluid remaining in the nozzle together with the first liquid.

In the maintenance method for the liquid ejecting apparatus, it is preferable that the mixed fluid is ejected a plurality of times at time intervals.
According to this configuration, even when the mixed fluid ejected to the liquid ejecting unit becomes foamy and closes the nozzle opening, the foamed mixed fluid that closes the nozzle opening while the ejection of the mixed fluid is stopped Return to droplets. For this reason, the mixed fluid previously injected into the liquid ejecting unit and foamed to block the nozzle opening prevents the liquid droplets in the mixed fluid subsequently ejected into the liquid ejecting unit from entering the nozzle. It can be suppressed.

In the maintenance method of the liquid ejecting apparatus, it is preferable that the second liquid is ejected to the liquid ejecting unit including the nozzle before ejecting the mixed fluid.
According to this configuration, the second liquid is ejected first with respect to the liquid ejecting unit, and then the mixed fluid is ejected by mixing the gas into the second liquid. It can suppress that only gas is injected. Therefore, it is possible to suppress the gas injected to the liquid ejecting unit from entering the interior of the liquid ejecting unit from the nozzle opening.

1 is a schematic side view of a printer according to an embodiment. FIG. 3 is a schematic cross-sectional view of a liquid jet head. FIG. 3 is a schematic plan view showing a printing unit and maintenance units arranged in a non-printing area. FIG. 2 is a schematic plan view showing a detailed configuration of a printing unit and maintenance units arranged in a non-printing area. The schematic plan view which shows the 2 fluid injection apparatus arrange | positioned at a printing part and a non-printing area | region. The cross-sectional schematic diagram which shows the detailed structure of a 2 fluid injection apparatus. The perspective view of an injection unit. The side cross-sectional schematic diagram which shows the use condition of an injection unit. FIG. 3 is a block diagram illustrating an electrical configuration of the printer. The side cross-sectional schematic diagram which shows the use condition of an injection unit. The side cross-sectional schematic diagram which shows the standby state of an injection unit. The side cross-sectional schematic diagram of the 2 fluid injection nozzle of the example of a change.

Hereinafter, as an example of a liquid ejecting apparatus, an embodiment of an ink jet printer that ejects ink and prints an image including characters and figures will be described with reference to the drawings.
As shown in FIG. 1, the printer 11 includes a transport unit 13 that transports a sheet ST as an example of a medium supported by the support base 12 in the transport direction Y along the surface of the support base 12, and the transported sheet ST. In addition, a printing unit 20 that performs printing by ejecting ink as an example of the first liquid, and a heating unit 17 and a blowing unit 18 for drying the ink that has landed on the sheet ST are provided.

  The support 12, the transport unit 13, the heat generating unit 17, the air blowing unit 18, and the printing unit 20 are assembled in a printer main body 11 a that includes a housing and a frame. The support 12 is provided in the printer 11 so as to extend in the width direction of the sheet ST (a direction orthogonal to the paper surface in FIG. 1).

  The transport unit 13 includes a transport roller pair 14a and a transport roller pair 14b that are respectively disposed on the upstream side and the downstream side of the support base 12 in the transport direction Y and are driven by a transport motor 49 (see FIG. 9). Further, the transport unit 13 includes a guide plate 15a and a guide plate 15b that are arranged on the upstream side and the downstream side of the transport roller pair 14a and the transport roller pair 14b in the transport direction Y and guide the sheet ST while supporting it. .

  Then, the conveyance unit 13 conveys the sheet ST along the surface of the support base 12 and the surfaces of the guide plates 15a and 15b by the conveyance roller pair 14a and 14b rotating while sandwiching the sheet ST. In the present embodiment, the sheet ST is continuously conveyed by being fed out from the roll sheet RS wound around the supply reel 16a in a roll shape. Then, the sheet ST that is fed out from the roll sheet RS and continuously conveyed is printed on the roll by the take-up reel 16b again after the printing unit 20 has the ink attached thereto to print an image.

  The printing unit 20 is guided by guide shafts 21 and 22 extending along a scanning direction X that is a width direction of the sheet ST orthogonal to the transport direction Y of the sheet ST, and the carriage motor 48 (see FIG. 9). A carriage 23 that can reciprocate in the scanning direction X by power is provided. The carriage 23 includes two liquid ejecting heads 24A and 24B as an example of a liquid ejecting section that ejects ink, a storage section 30 that stores ink to be supplied to the liquid ejecting heads 24A and 24B, and a flow path to the storage section 30. A connection tube 27 that supplies ink via an adapter 28 is attached. The reservoir 30 is held by a reservoir holder 25 attached to the carriage 23.

  As shown in FIGS. 1 and 2, the storage unit 30 includes a differential pressure valve 31 provided in the middle of the first ink supply path 32 for supplying internal ink to the liquid ejecting heads 24 </ b> A and 24 </ b> B. . The differential pressure valve 31 is opened when the pressure of the ink on the downstream side becomes a predetermined negative pressure with respect to the atmospheric pressure as the ink is ejected (consumed) by the liquid ejecting heads 24A and 24B located on the downstream side thereof. When ink is supplied from the reservoir 30 to the liquid ejecting heads 24A and 24B by opening the valve and the negative pressure on the downstream side is eliminated, the valve is closed.

  As shown in FIG. 2, the liquid ejecting heads 24 </ b> A and 24 </ b> B include a cylindrical main body case 33. A second ink supply path 34 that penetrates the main body case 33 in the vertical direction Z is formed at a position near the one end portion in the scanning direction X in the main body case 33, and a fixed plate 35 is located at a position near the other end portion in the scanning direction X. Is erected. The downstream end of the first ink supply path 32 is connected to the upstream end of the second ink supply path 34.

  An elastic rectangular thin plate-shaped diaphragm 36 is fixed to the lower surface of the main body case 33 so as to cover the lower end opening of the main body case 33 and the lower end opening of the second ink supply path 34. In the main body case 33, one side surface at the upper end of a piezoelectric element 37 as an example of an actuator is fixed to the fixing plate 35, and the lower surface of the piezoelectric element 37 is fixed to the upper surface of the vibration plate 36.

  On the lower side of the piezoelectric element 37, a plurality of notch grooves (not shown) extending across the entire width in the scanning direction X of the piezoelectric element 37 are provided at intervals in the transport direction Y. The depth of each notch groove (not shown) is set to about half the height of the piezoelectric element 37 in the vertical direction Z. A portion sandwiched between the notch grooves (not shown) in the piezoelectric element 37 is a piezoelectric element portion 37a. Grooves 38 are formed in a lattice shape on the upper surface of the diaphragm 36 so as to surround each piezoelectric element portion 37 a, and an eye portion of the lattice-shaped groove 38 is an island portion 39.

  A flow path forming plate 40 having a rectangular frame shape is fixed in close contact with the lower surface of the vibration plate 36, and a rectangular plate shaped nozzle plate 41 is fixed in close contact with the lower surface of the flow path forming plate 40. An ink storage chamber 42 is formed near the one end in the scanning direction X between the vibration plate 36 and the nozzle plate 41. The ink storage chamber 42 communicates with the second ink supply path 34 through a communication hole 43 formed in the vibration plate 36. The ink storage chamber 42 temporarily stores ink supplied from the storage unit 30 via the second ink supply path 34.

  At a position near the other end in the scanning direction X between the vibration plate 36 and the nozzle plate 41, a pressure chamber 44 corresponding to each piezoelectric element portion 37a in the vertical direction Z is formed. Between the ink storage chamber 42 and the pressure chambers 44 between the vibration plate 36 and the nozzle plate 41, communication paths 45 that connect the ink storage chambers 42 and the pressure chambers 44 are respectively formed.

  Therefore, the ink temporarily stored in the ink storage chamber 42 is supplied to each pressure chamber 44 via each communication path 45. Nozzles 46 are respectively provided at positions corresponding to the pressure chambers 44 in the nozzle plate 41, and the lower surface of the nozzle plate 41 is a nozzle forming surface 24a in which the nozzles 46 are opened. Each nozzle 46 communicates with each pressure chamber 44.

  One end of a strip-like flexible circuit board 47 is connected to the side surface of the upper end of the piezoelectric element 37 opposite to the fixed plate 35 side, and the other end of the flexible circuit board 47 is connected to a control unit 110 (see FIG. 9). The piezoelectric elements 37 are individually expanded and contracted along the vertical direction Z by the drive signals generated by the control unit 110 (see FIG. 9) being input via the flexible circuit board 47. Drive) is possible.

  Then, the island portions 39 of the diaphragm 36 vibrate based on the expansion and contraction movement of the piezoelectric element portions 37a, whereby the pressure in each pressure chamber 44 is changed, and each pressure chamber is changed by the pressure change in each pressure chamber 44. The ink in the nozzle 44 is ejected from the opening of each nozzle 46. The piezoelectric element 37 is in a state where each piezoelectric element portion 37a is displaced (contracted) in a direction in which a voltage is applied to the piezoelectric element 37 and the diaphragm 36 is elastically deformed to increase the volume of each pressure chamber 44. The pressure chambers 44 can be pressurized by stopping the application of voltage to the piezoelectric element 37 and bringing the diaphragm 36 into a state before elastic deformation.

  As shown in FIGS. 1 and 2, the liquid ejecting heads 24 </ b> A and 24 </ b> B are attached to the lower end portion of the carriage 23 with the nozzle forming surface 24 a facing the support base 12 at a predetermined interval in the vertical direction Z. . On the other hand, the storage unit 30 is attached to the upper side that is opposite to the liquid jet heads 24 </ b> A and 24 </ b> B in the vertical direction Z with respect to the carriage 23. In addition, the downstream end of the connection tube 27 is connected to the flow path adapter 28 at a position above the reservoir 30.

  The upstream end portion of the connection tube 27 is connected to the downstream end portions of the plurality of ink supply tubes 26 that can be deformed following the reciprocating carriage 23 and the connection portion 26 a attached to a part of the carriage 23. It is connected. Therefore, for example, ink from an ink tank (not shown) containing ink is supplied to the storage unit 30 via the ink supply tube 26, the connection tube 27, and the flow path adapter 28.

  In the printing unit 20, ink is ejected from the openings of the plurality of nozzles 46 of the liquid ejecting heads 24 </ b> A and 24 </ b> B to the sheet ST on the support base 12 in the process in which the carriage 23 moves (reciprocates) in the scanning direction X. The heat generating portion 17 for heating and drying the ink that has landed on the sheet ST is disposed at an upper position in the printer 11 with a predetermined length interval from the support base 12 in the vertical direction Z. The printing unit 20 can reciprocate between the heat generating unit 17 and the support base 12 along the scanning direction X.

  The heat generating portion 17 includes a heat generating member 17a such as an infrared heater and a reflecting plate 17b extending along the same scanning direction X as the extending direction of the support base 12, and is in an area indicated by a one-dot chain line arrow in FIG. The ink adhering to the sheet ST is heated by radiated heat such as infrared rays (for example, radiant heat). In addition, the air blowing unit 18 that dries the ink attached to the sheet ST by the air blowing is disposed at an upper position that is spaced from the support base 12 so that the printing unit 20 can reciprocate in the printer 11.

  A heat shield member 29 that blocks heat transfer from the heat generating portion 17 is provided at a position between the storage portion 30 and the heat generating portion 17 in the carriage 23. The heat shielding member 29 is made of a metal material having good thermal conductivity such as stainless steel or aluminum, and covers at least the upper surface portion of the storage portion 30 facing the heat generating portion 17.

  In the printer 11, the storage unit 30 is provided for each ink type. The printer 11 according to the present embodiment includes a storage unit 30 that stores colored ink, and can perform color printing and monochrome printing. For example, the ink colors of the colored ink are cyan, magenta, yellow, black, and white. Each colored ink contains a preservative.

  The white ink is used for, for example, base printing (solid printing (filled printing)) before color printing when the sheet ST is a transparent or translucent film or a dark medium. The Of course, the color ink to be used can be arbitrarily selected, and may be, for example, three colors of cyan, magenta, and yellow. In addition to the above three colors, at least one color among light cyan, light magenta, light yellow, orange, green, gray, and the like can be further added to the colored ink.

  As shown in FIG. 3, ink droplets ejected from the openings of the nozzles 46 (see FIG. 2) of the liquid ejecting heads 24 </ b> A and 24 </ b> B are landed on the maximum width sheet ST conveyed on the support base 12. The area of the maximum width in the possible scanning direction X is a print area PA. That is, the ink droplets ejected from the openings of the nozzles 46 (see FIG. 2) of the liquid ejecting heads 24A and 24B to the sheet ST land in the printing area PA.

  A wiper unit 50, a flushing unit 51, and a cap unit 52 are provided in a non-printing area NA where the liquid ejecting heads 24A and 24B movable in the scanning direction X do not face the sheet ST being conveyed. Yes. When the printing unit 20 has a borderless printing function, the printing area PA is slightly wider in the scanning direction X than the range of the maximum width sheet ST to be conveyed.

  The wiper unit 50 has a wiper 50a for wiping the nozzle forming surface 24a (see FIG. 1). The wiper 50 a of this embodiment is movable and performs a wiping operation with the power of the wiping motor 53. The flushing unit 51 includes a liquid receiving portion 51a that receives ink droplets ejected from the openings of the nozzles 46 (see FIG. 2) of the liquid ejecting heads 24A and 24B.

  The liquid receiving portion 51a of the present embodiment is constituted by a belt, and moves the belt by the power of the flushing motor 54 at a predetermined time when the amount of ink stain due to the flushing of the belt can be regarded as exceeding a specified amount. Note that flushing is an operation for forcibly ejecting (discharging) ink droplets from all the nozzles 46 irrespective of printing for the purpose of preventing and eliminating clogging of the nozzles 46 (see FIG. 2).

  The cap unit 52 has two cap portions 52a that can contact the nozzle forming surfaces 24a (see FIG. 1) of the two liquid jet heads 24A and 24B so as to surround the openings of the nozzles 46. The two cap portions 52a are configured to be movable between a contact position that contacts the nozzle forming surface 24a and a retracted position away from the nozzle forming surface 24a by the power of the capping motor 55. The positions at which the liquid ejecting heads 24A and 24B are capped by the corresponding cap portions 52a are the home positions HP of the liquid ejecting heads 24A and 24B (or the carriage 23).

  As shown in FIG. 4, the two liquid jet heads 24A and 24B attached to the lower end portion of the carriage 23 are arranged so as to be separated by a predetermined distance in the scanning direction X and shifted by a predetermined distance in the transport direction Y. ing. On the nozzle formation surface 24a of the liquid ejecting heads 24A and 24B, a total of eight nozzle rows 24b in which two rows located close to each other are arranged at regular intervals in the scanning direction X are formed.

  The eight nozzle rows 24b formed on the nozzle forming surface 24a are each composed of a large number (for example, 180) of nozzles 46 formed at a constant nozzle pitch in the transport direction Y. The two liquid ejecting heads 24A and 24B have the same nozzle pitch between the nozzles 46 at the ends of the two liquid ejecting heads 24A and 24B when the plurality of nozzles 46 constituting the nozzle row 24b are projected in the scanning direction X. The positional relationship in the transporting direction Y is possible.

  The wiper unit 50 includes a movable housing 59 that can reciprocate on a pair of rails 58 extending in the transport direction Y by the power of the wiping motor 53. In the housing 59, a feeding shaft 60 and a winding shaft 61 that are positioned at a predetermined distance in the wiping direction (same as the transport direction Y) are rotatably supported. A feeding roll 63 around which an unused cloth sheet 62 is wound is mounted on the feeding shaft 60, and a winding roll 64 on which a used cloth sheet 62 is wound is mounted on the winding shaft 61.

  The cloth sheet 62 hung between the feeding roll 63 and the take-up roll 64 is wound around the upper surface of the pressing roller 65 in a state of partially protruding upward from an opening (not shown) at the center of the upper surface of the housing 59, A semi-cylindrical (convex) wiper 50 a is formed at a portion wound around the pressing roller 65. The wiper 50a is biased upward.

  The casing 59 is a wiping direction through a cassette that houses the feeding roll 63 and the take-up roll 64, and a power transmission mechanism (for example, a rack and pinion mechanism) that is guided by the rail 58 and that is not illustrated by the power of the wiping motor 53. It is comprised from the holder which can reciprocately move (same in the conveyance direction Y). The housing 59 is driven in the transport direction Y between the retracted position shown in FIG. 4 and the wiping position at which the wiper 50a finishes wiping the nozzle forming surface 24a when the wiping motor 53 is driven forward and backward. Move back and forth.

  At this time, when the forward movement of the housing 59 is finished, the power transmission mechanism is switched to a state in which the wiping motor 53 and the winding shaft 61 are connected so as to be able to transmit power, and the power when the wiping motor 53 is driven in reverse rotation is switched. A backward movement operation of the housing 59 and a predetermined amount of winding operation of the cloth sheet 62 around the winding roll 64 are performed. The two liquid ejecting heads 24A and 24B are sequentially moved with respect to the wiping area WA, and the wiping of each of the two liquid ejecting heads 24A and 24B by the reciprocating movement of the housing 59 with respect to the nozzle forming surface 24a is performed in the wiping area WA. Each moved one is done individually.

  The flushing unit 51 includes a driving roller 66 and a driven roller 67 that are parallel to each other in the transport direction Y, and an endless belt 68 that is wound between the driving roller 66 and the driven roller 67. The belt 68 has a width equal to or greater than eight (2 × 4) nozzle rows 24b in the scanning direction X, and receives the ink ejected from the nozzles 46 of the liquid ejecting heads 24A and 24B. The liquid receiving portion 51a is configured. In this case, the outer peripheral surface of the belt 68 is a liquid receiving surface 69 that receives ink.

  The flushing unit 51 has a moisturizing liquid supply unit (not shown) capable of supplying a moisturizing liquid to the liquid receiving surface 69 below the belt 68, and a liquid that scrapes off waste ink and the like adhering to the liquid receiving surface 69 in a moisturizing state. The waste ink received by the liquid receiving surface 69 is removed from the belt 68 by the liquid scraping portion. Therefore, the receiving range of the liquid receiving surface 69 facing the nozzle forming surface 24a is updated by the circular movement of the belt 68.

  The cap unit 52 has two cap portions 52a that can be in contact with the nozzle forming surfaces 24a of the two liquid ejecting heads 24A and 24B to form a sealed space. As described above, each cap portion 52a moves between a contact position where it can contact the nozzle forming surface 24a and a retracted position away from the nozzle forming surface 24a by the power of the capping motor 55. Each cap 52a includes one suction cap 70 and four moisturizing caps 71.

  Each of the moisturizing caps 71 is in contact with the nozzle forming surface 24a to form a sealed space surrounding the two nozzle rows 24b, and keeps the sealed space moisturized. Specifically, the dispersion medium or solvent (for example, water or the like) contained in the waste ink remaining in the moisturizing cap 71, or the ink in the nozzle 46 opened in the moisturizing cap 71 due to evaporation or volatilization of the moisturizing liquid. Moisturized.

  The suction cap 70 is connected to a suction pump 73 via a tube 72. Then, by driving the suction pump 73 in a state where the suction cap 70 is in contact with the nozzle forming surface 24a to form a sealed space, the ink 46 can be increased in viscosity from the nozzle 46 due to the negative pressure acting in the suction cap 70. So-called cleaning is performed in which bubbles and the like are sucked and discharged together with ink.

  Such cleaning is performed on the liquid jet heads 24A and 24B by two nozzle rows 24b. After the cleaning is completed, wiping for removing ink adhering to the nozzle forming surface 24a and flushing for adjusting the ink meniscus in the nozzle 46 are sequentially performed.

  As shown in FIG. 4, the moving area in which the liquid ejecting heads 24A and 24B can move in the scanning direction X includes a printing area PA in which ink can be landed from the nozzles 46 of the liquid ejecting heads 24A and 24B when the sheet ST is printed, Other non-printing areas NA are included. The non-printing area NA includes a wiping area WA in which the wiper unit 50 is provided, a receiving area FA in which the flushing unit 51 is provided, and a maintenance area MA in which the cap unit 52 is provided.

  That is, in the non-printing area NA, the wiping area WA, the receiving area FA, and the maintenance area MA are arranged in the order of the wiping area WA, the receiving area FA, and the maintenance area MA from the printing area PA side in the scanning direction X. Yes. Further, in a region corresponding to the print region PA in the scanning direction X, a heating region HA provided with a heat generating portion 17 for fixing the ink landed on the sheet ST by heating is disposed.

  As shown in FIGS. 3 and 5, the non-printing area NA exists on both sides of the printing area PA in the scanning direction X. The two-fluid ejecting device 75 for cleaning the liquid ejecting heads 24A and 24B is applied to the non-printing region NA located on the opposite side of the home position HP in the scanning direction X among these two non-printing regions NA. Is provided.

  The two-fluid ejecting device 75 can eject at least one of cleaning liquid that is liquid (second liquid) containing preservative in air (gas) and pure water to the liquid ejecting heads 24A and 24B. It is configured. The two-fluid ejecting device 75 can eject the mixed fluid in which the air and the cleaning liquid are mixed by ejecting the air and the cleaning liquid together.

  The cleaning liquid is preferably the same as the main solvent of the ink used. In this embodiment, since the water-based resin ink in which the ink solvent is water is used, pure water is used as the cleaning liquid. For example, when the ink solvent is the solvent, the ink is used as the cleaning liquid. It is preferable to use the same solvent.

  The preservative contained in the cleaning liquid is preferably the same as the preservative contained in the ink. For example, an aromatic halogen compound (for example, Preventol CMK), methylene dithiocyanate, halogen-containing nitrogen sulfur A compound, 1,2-benzisothiazolin-3-one (for example, PROXEL GXL) and the like. When PROXEL is employed as a preservative from the viewpoint of difficulty in foaming, the content of the cleaning liquid is preferably 0.05 mass percent or less.

  As shown in FIG. 6, the two-fluid ejection device 75 includes an ejection unit 77, and the ejection unit 77 includes a two-fluid ejection nozzle 78 that can eject a mixed fluid. The two-fluid ejection nozzle 78 is disposed so as to eject the mixed fluid upward. The two-fluid ejection nozzle 78 includes a liquid ejection nozzle 80 that ejects cleaning liquid upward, and an annular gas ejection nozzle 81 that ejects air upward and surrounds the liquid ejection nozzle 80. ing.

  That is, both the liquid jet nozzle 80 and the gas jet nozzle 81 are open upward. The diameter of the opening of the liquid ejecting nozzle 80 is preferably sufficiently larger than the diameter of the opening of the nozzle 46 of the liquid ejecting heads 24A and 24B in consideration of ink adhering and solidifying, for example, 0.4 mm or more. It is preferable. In this embodiment, the diameter of the opening of the liquid jet nozzle 80 is set to 1.1 mm.

  Further, the two-fluid injection nozzle 78 of the present embodiment employs a so-called external mixing type in which a mixing portion KA in which the cleaning liquid and air are mixed is located outside the two-fluid injection nozzle 78. . Therefore, the mixing unit KA is configured by a predetermined space adjacent to the opening of the liquid injection nozzle 80 and the opening of the gas injection nozzle 81. A gas supply pipe 83 that forms a gas channel 83 a for supplying air from the air pump 82 is connected to the two-fluid injection nozzle 78. The gas flow path 83 a communicates with the gas injection nozzle 81.

  A pressure adjusting valve 84 that adjusts the pressure of the air supplied from the air pump 82 is provided in the middle of the gas supply pipe 83. In the two-fluid ejection device 75 of this embodiment, the pressure of the air supplied from the air pump 82 to the two-fluid ejection nozzle 78 is set to be 200 kPa or more. A filter 85 for removing dust or the like in the air supplied to the two-fluid injection nozzle 78 is provided at a position between the pressure adjustment valve 84 and the two-fluid injection nozzle 78 in the gas supply pipe 83.

  The two-fluid ejection nozzle 78 is connected to a liquid supply pipe 88 that forms a liquid flow path 88a for supplying a cleaning liquid stored in a storage tank 87 as an example of a liquid storage unit. The liquid flow path 88a communicates with the liquid jet nozzle 80. The upper end of the storage tank 87 is provided with an air release pipe 89 that opens the liquid storage space SK in the storage tank 87 to the atmosphere, and the air release pipe 89 is provided with a first electromagnetic valve 90 as an example of an on-off valve. Yes.

  Therefore, when the first electromagnetic valve 90 is opened, the liquid storage space SK is in communication with the atmosphere via the atmosphere release pipe 89, while when the first electromagnetic valve 90 is closed, the liquid storage space SK. Is in a non-communication state that does not communicate with the atmosphere. That is, the first electromagnetic valve 90 is configured to be able to switch the liquid storage space SK between a communication state and a non-communication state by opening and closing.

  The storage tank 87 stores cleaning liquid and is connected via a supply pipe 92 to a cleaning liquid cartridge 91 that is detachably attached to the printer main body 11a (see FIG. 1). A liquid supply pump 93 for supplying the cleaning liquid in the cleaning liquid cartridge 91 to the storage tank 87 is provided in the middle of the supply pipe 92. A second electromagnetic valve 94 for opening and closing the supply pipe 92 is provided at a position between the liquid supply pump 93 and the storage tank 87 in the supply pipe 92.

  As shown in FIGS. 7 and 8, the injection unit 77 includes a base member 100 having a bottomed substantially rectangular box shape, a support member 101 that is disposed in the base member 100 and supports the two-fluid injection nozzle 78, and a base member And a rectangular cylindrical case 102 that accommodates the two-fluid injection nozzle 78 and the support member 101. The two-fluid ejection nozzle 78 is fixed to the support member 101, and the support member 101 and the case 102 are configured to be capable of individually reciprocating along the transport direction Y in the base member 100.

  In addition, the ejection unit 77 includes a cleaning motor 103, a transmission mechanism 104 that transmits the driving force of the cleaning motor 103 to the support member 101, and a side plate 105 that is erected at an end portion on the printing area PA side. The support member 101 is reciprocated along the transport direction Y together with the two-fluid ejection nozzle 78 by transmitting the driving force of the cleaning motor 103 via the transmission mechanism 104. In this case, when the case 102 is pressed from the inside by the support member 101, the case 102 is reciprocated along the transport direction Y together with the support member 101.

  A cover member 106 as an example of a mating member that closes the upper end opening of the case 102 is attached to the case 102. A rectangular through hole 107 extending in the transport direction Y is formed at a position overlapping with a part of the moving region of the two-fluid ejection nozzle 78 in the vertical direction Z on the upper surface of the cover member 106. On the upper surface of the cover member 106, a rectangular frame-shaped lip portion 108 surrounding the through hole 107 is provided.

  A guide portion (not shown) for guiding the case 102 when the case 102 reciprocates along the transport direction Y is provided on the surface of the side plate 105 on the case 102 side. As shown in FIGS. 8 and 10, the guide portions (not shown) are arranged in two rows in which the case 102 rises at positions corresponding to the liquid jet heads 24 </ b> A and 24 </ b> B, and the lip portions 108 are located close to each other. The case 102 is guided so as to come into contact with the nozzle forming surface 24a while surrounding the nozzle row 24b.

  In the present embodiment, the distance between the two-fluid ejection nozzle 78 and the nozzle forming surface 24a in the vertical direction Z is set to about 5 mm, and the sheet ST and nozzle formation supported by the support base 12 shown in FIG. It is longer than the distance (about 1 mm) from the surface 24a.

Next, the electrical configuration of the printer 11 will be described.
As shown in FIG. 9, the printer 11 includes a control unit 110 that controls the printer 11 in an integrated manner. The control unit 110 is electrically connected to the linear encoder 111. The linear encoder 111 has a tape-shaped code plate provided on the back side of the carriage 23 so as to extend along the guide shaft 22 and a fixed pitch fixed to the carriage 23 (see FIG. 1) and perforated in the code plate. And a sensor for detecting light transmitted through the slit.

  The control unit 110 inputs a number of pulses proportional to the amount of movement of the printing unit 20 (see FIG. 1) from the linear encoder 111, and the printing unit 20 sets the number of pulses input to the home position HP (see FIG. 3). The position of the printing unit 20 in the scanning direction X is grasped by adding the value when moving away from the position and subtracting the value when approaching the home position HP.

  A rotary encoder 112 is electrically connected to the control unit 110. The rotary encoder 112 includes a disk-shaped code plate attached to the output shaft of the cleaning motor 103 and a sensor that detects light transmitted through slits of a constant pitch perforated in the code plate.

  The control unit 110 inputs a number of pulses proportional to the amount of movement of the support member 101 from the rotary encoder 112, and determines the number of input pulses when the support member 101 leaves the standby position (the position shown in FIG. 11). By adding and subtracting when approaching the standby position, the position of the support member 101 (two-fluid ejection nozzle 78) in the transport direction Y is grasped.

  The control unit 110 is electrically connected to the piezoelectric element 37 via the drive circuit 113 and controls the driving of the piezoelectric element 37. The control unit 110 grasps clogging of each nozzle 46 based on the period of residual vibration of each island portion 39 of the diaphragm 36 by driving the piezoelectric element 37 (each piezoelectric element portion 37a).

  The control unit 110 is electrically connected to the cleaning motor 103, the carriage motor 48, the transport motor 49, the wiping motor 53, the flushing motor 54, and the capping motor 55 via motor drive circuits 114 to 119, respectively. The control unit 110 controls driving of the motors 103, 48, 49, 53, 54, and 55, respectively.

  The control unit 110 is electrically connected to the suction pump 73, the air pump 82, and the liquid supply pump 93 via the pump drive circuits 120 to 122, respectively. And the control part 110 drive-controls the pumps 73, 82, and 93, respectively. The controller 110 is electrically connected to the first electromagnetic valve 90 and the second electromagnetic valve 94 via valve drive circuits 123 and 124, respectively. And the control part 110 drive-controls the solenoid valves 90 and 94, respectively.

Next, the operation of the printer 11 will be described.
When print data is input to the control unit 110 from an external device, the control unit 110 drives the carriage motor 48 based on the print data, and the liquid ejecting heads 24A and 24B move while the printing unit 20 moves in the scanning direction X. Ink droplets are ejected from the nozzles 46 toward the surface of the sheet ST. Then, the ejected ink droplets land on the surface of the sheet ST, so that an image or the like is printed on the surface of the sheet ST.

  By the way, during the printing of the sheet ST, for the purpose of preventing thickening of ink in the nozzles 46 that do not eject ink droplets among all the nozzles 46, every predetermined time (for example, within a range of 10 to 30 seconds). ), The printing unit 20 moves to the receiving area FA, and performs flushing for ejecting and discharging ink droplets from all the nozzles 46.

  When a predetermined cleaning condition is satisfied, the control unit 110 controls the carriage motor 48 to move the printing unit 20 to the home position HP for cleaning. The cleaning is performed by driving the suction pump 73 in a state where the suction cap 70 is brought into contact with the nozzle formation surface 24a so as to surround the nozzle row 24b to form a sealed space, thereby applying a negative pressure to the suction cap 70. Then, a predetermined amount of ink is sucked from each nozzle 46 to remove thickened ink and bubbles. After the cleaning is completed, the control unit 110 moves the printing unit 20 to the wiping area WA and wipes the nozzle forming surface 24a with the wiper 50a, and then moves the printing unit 20 to the receiving area FA and moves toward the liquid receiving part 51a. To flush.

  Thereafter, the control unit 110 detects clogging of each nozzle 46 based on the period of residual vibration of each island portion 39 of the diaphragm 36 by driving the piezoelectric element 37 (each piezoelectric element portion 37a). Here, the clogging of each nozzle 46 is detected after the cleaning is finished, in particular, using a resin ink containing a synthetic resin that is cured by heating, or a UV ink that is cured by UV (ultraviolet) irradiation. This is because the nozzle 46 may not be clogged even after cleaning. Here, the clogging is not only the state in which the ink in the nozzle 46 is solidified and clogged, but also the ink in the nozzle 46, the pressure chamber 44, and the communication passage 45 is thickened to increase the viscosity of the nozzle 46. Including the state where ink cannot be ejected (ejected) normally.

  If the clogging of all the nozzles 46 is not detected and the print job is waiting, the control unit 110 moves the printing unit 20 to the printing area PA and prints the sheet ST. On the other hand, when the clogged nozzle 46 is detected among all the nozzles 46, the control unit 110 moves the printing unit 20 to the non-printing area NA on the side opposite to the home position HP side in the scanning direction X. The clogging of the nozzle 46 is eliminated by cleaning the clogged nozzle 46 with the two-fluid ejection device 75.

  When the clogged nozzle 46 is cleaned by the two-fluid ejecting device 75, these positions are set so that the clogged nozzle 46 and the two-fluid ejecting nozzle 78 face each other in the vertical direction Z. Match. In this case, the clogging nozzle 46 and the two-fluid ejection nozzle 78 are aligned in the scanning direction X (direction orthogonal to the direction in which the nozzle row 24b extends) by the movement of the printing unit 20 and clogging. Positioning of the nozzle 46 and the two-fluid ejection nozzle 78 in the transport direction Y (the direction in which the nozzle row 24 b extends) is performed by moving the two-fluid ejection nozzle 78.

  Specifically, when the clogged nozzle 46 is in the liquid jet head 24A, the lip portion 108 is clogged after the alignment of the printing unit 20 in the scanning direction X as shown in FIG. The case 102 is moved via the support member 101 so as to contact the nozzle forming surface 24a in a state of surrounding the nozzle row 24b including the nozzles 46. Subsequently, the two-fluid ejection nozzle 78 is moved via the support member 101 so that the liquid ejection nozzle 80 of the two-fluid ejection nozzle 78 faces the clogged nozzle 46, and the position of the two-fluid ejection nozzle 78 in the transport direction Y is reached. Adjust.

  At this time, in a normal state before the mixed fluid is ejected from the two-fluid ejection nozzle 78, as shown in FIG. 6, the first electromagnetic valve 90 is opened and the liquid storage space SK is in a communication state communicating with the atmosphere. At the same time, the second electromagnetic valve 94 is closed. In this state, the height H of the gas-liquid interface KK of the cleaning liquid in the liquid channel 88a is set to be −100 to −1000 mm when the height of the tip of the two-fluid ejection nozzle 78 is zero. It is preferred that In the present embodiment, the height H when the height of the tip of the two-fluid ejection nozzle 78 is set to 0 is set to −150 mm.

  6 and 8, when the air pump 82 is driven to supply air to the two-fluid injection nozzle 78, air is injected from the gas injection nozzle 81. The cleaning liquid in the liquid flow path 88a is sucked up by the negative pressure generated by the jetting of air and jetted from the liquid jet nozzle 80. Thereby, air and the cleaning liquid are mixed in the mixing unit KA to generate a mixed fluid, and the mixed fluid is sprayed onto a partial region of the nozzle forming surface 24a including the clogged nozzle 46.

  The mixed fluid includes a large number of liquid cleaning liquid droplets whose diameter is smaller than the opening diameter of the nozzle 46 and is 20 μm or less. At this time, the jet speed of the mixed fluid from the two-fluid jet nozzle 78 is 40 m / sec. It is set to be the above. The kinetic energy of the droplet-like cleaning liquid ejected at this time having a diameter of 20 μm or less cannot be destroyed by the energy transmitted to the gas-liquid interface in the nozzle 46 by the ink ejection operation or flushing operation during printing. It is preferably equal to or greater than the kinetic energy capable of breaking the film-like ink solidified at the interface.

  Therefore, the product of the mass of the droplet of the cleaning liquid having a diameter smaller than the opening diameter of the nozzle 46 and the square of the flying speed of the droplet at the opening position of the nozzle 46 is ejected from the opening of the nozzle 46. It is set to be larger than the product of the mass of the ink droplet and the square of the flying speed of the ink droplet.

  Further, the ejection of the mixed fluid to the clogged nozzle 46 is performed by causing the ink in the pressure chamber 44 communicating with the clogged nozzle 46 to drive the island portion 39 of the diaphragm 36 by driving the piezoelectric element portion 37 a corresponding to the pressure chamber 44. It is performed in a state of being pressurized by the vibration of. When the mixed fluid is ejected from the two-fluid ejecting nozzle 78 to the clogged nozzle 46, a droplet-like cleaning liquid smaller than the opening diameter of the nozzle 46 in the mixed fluid passes through the opening of the nozzle 46 and enters the nozzle 46. It enters into and collides with the clogged part.

  That is, the liquid cleaning liquid in a droplet form smaller than the opening diameter of the nozzle 46 collides with the ink solidified in the nozzle 46. The solidified ink is destroyed by the impact of the cleaning liquid on the solidified ink at this time, and the clogging of the nozzle 46 is eliminated. At this time, since the ink in the pressure chamber 44 communicating with the nozzle 46 in which the clogging has been eliminated is pressurized, the mixed fluid that has entered the nozzle 46 passes through the pressure chamber 44 and is a liquid ejecting head. The entry into the back of 24A is suppressed.

  When stopping the injection of the mixed fluid from the two-fluid injection nozzle 78, first, the first electromagnetic valve 90 is closed while the mixed fluid is being injected from the two-fluid injection nozzle 78. The accommodation space SK is switched from a communication state communicating with the atmosphere to a non-communication state not communicating with the atmosphere. Then, since the liquid storage space SK has a negative pressure, the cleaning liquid ejected from the liquid ejection nozzle 80 is drawn into the liquid flow path 88a by the action of the negative pressure.

  Thereby, the gas-liquid interface KK (water head surface of the storage tank 87) of the cleaning liquid in the liquid flow path 88a is positioned on the lower side (storage tank 87 side) than the mixing unit KA. When the air pump 82 is stopped, air is not jetted from the gas jet nozzle 81. In this case, the air pump 82 is stopped in a state where the gas-liquid interface KK of the cleaning liquid in the liquid channel 88a is positioned below the mixing unit KA, so that the cleaning liquid in the liquid channel 88a is mixed with the mixing unit. The entry into the gas injection nozzle 81 beyond KA is suppressed.

  Furthermore, in this case, even after the supply of air from the air pump 82 to the gas injection nozzle 81 via the liquid flow path 88a is stopped, the closed state of the first electromagnetic valve 90 is maintained, and the liquid storage space SK is not in communication. Is maintained. Note that unnecessary cleaning liquid after cleaning the nozzle 46 and unnecessary ink washed away from the nozzle 46 flow down from the case 102 into the base member 100 and are disposed in the base member 100 (not shown). To a waste liquid tank (not shown).

  When the clogged nozzle 46 is also present in the liquid ejecting head 24B, as shown in FIG. 10, the lip portion 108 is clogged in the liquid ejecting head 24B as in the case of the liquid ejecting head 24A. The case 102 is moved via the support member 101 so as to contact the nozzle forming surface 24a in a state of surrounding the nozzle row 24b including the nozzles 46. Then, as in the case of the liquid ejecting head 24A, the mixed fluid is ejected to the clogged nozzle 46 of the liquid ejecting head 24B with the first electromagnetic valve 90 opened to eliminate the clogging of the nozzle 46. To do.

  Then, as shown in FIG. 11, after the cleaning of the clogged nozzles 46 of the liquid jet heads 24 </ b> A and 24 </ b> B by the two-fluid ejecting device 75 is finished, the mixed fluid is ejected from the two-fluid ejecting nozzle 78. The support member 101 is moved to the standby position, and the two-fluid ejection nozzle 78 is opposed to a position that does not correspond to the through hole 107 on the upper wall of the cover member 106. At this time, a slight gap is formed between the two-fluid ejection nozzle 78 and the upper wall of the cover member 106.

  Then, the air injected from the annular gas injection nozzle 81 surrounding the liquid injection nozzle 80 hits the upper wall of the cover member 106 and flows along the upper wall, so that the air is injected from the annular gas injection nozzle 81. The pressure inside the air, that is, the pressure above the liquid jet nozzle 80 increases. The cleaning liquid in the liquid flow path 88a is pressed downward (to the storage tank 87 side) by the increased pressure above the liquid jet nozzle 80. That is, the gas-liquid interface KK of the cleaning liquid in the liquid flow path 88a is pushed down far below the mixing portion KA.

  When the air pump 82 is stopped in this state, air is not jetted from the gas jet nozzle 81. In this case, the air pump 82 is stopped in a state where the gas-liquid interface KK of the cleaning liquid in the liquid channel 88a is positioned below the mixing unit KA, so that the cleaning liquid in the liquid channel 88a is mixed with the mixing unit. The entry into the gas injection nozzle 81 beyond KA is suppressed.

  Thereafter, the printing unit 20 is moved to the home position HP side, and cleaning and flushing are performed to discharge ink from the openings of the nozzles 46 of the liquid ejecting heads 24A and 24B, thereby remaining in the liquid ejecting heads 24A and 24B. The cleaning liquid and bubbles are removed. The cleaning and flushing at this time may be light and have a small ink discharge amount (consumption amount). This is because the mixed fluid is ejected to the clogged nozzle 46 in a state where the ink in the pressure chamber 44 communicating with the clogged nozzle 46 is pressurized as described above. This is because the entry (reverse flow) into the interior of the liquid jet heads 24A and 24B via 44 is suppressed.

As described above, according to the embodiment described in detail, the following effects can be obtained.
(1) The two-fluid ejecting device 75 includes a liquid including the nozzle 46 and a mixed fluid obtained by mixing a liquid in the form of liquid droplets including droplets smaller than the openings of the nozzles 46 of the liquid ejecting heads 24A and 24B. The ejection is performed on the ejection heads 24A and 24B. For this reason, the droplets of the cleaning liquid in the mixed fluid smaller than the opening of the nozzle 46 of the liquid jet heads 24A and 24B enter the nozzle 46 through the opening of the nozzle 46 and collide with the clogged portion. The clogging of 46 can be effectively eliminated.

  (2) The mass of the cleaning liquid droplet smaller than the opening of the nozzle 46 when the mixed fluid is ejected from the two-fluid ejection nozzle 78 to the nozzle 46 and the flying speed of the droplet at the opening position of the nozzle 46 are 2 The product of the power is larger than the product of the mass of the ink droplet ejected from the opening of the nozzle 46 and the square of the flying speed of the ink droplet. For this reason, clogging in the nozzle 46 that cannot be eliminated even by performing cleaning or flushing that discharges ink droplets from the opening of the nozzle 46, movement at the time of collision of the cleaning liquid droplet with the clogged portion in the nozzle 46. It can be solved by energy.

  (3) The ejection of the mixed fluid from the two-fluid ejection nozzle 78 to the clogged nozzle 46 is performed by the ink in the pressure chamber 44 communicating with the clogged nozzle 46 being in the piezoelectric element portion 37 a corresponding to the pressure chamber 44. This is performed in a state where it is pressurized by the vibration of the island portion 39 of the vibration plate 36 by driving. For this reason, it is possible to suppress the mixed fluid that has been ejected to the clogged nozzle 46 and entered into the nozzle 46 from entering the interior of the liquid ejecting heads 24A and 24B via the pressure chamber 44. .

  (4) Since the cleaning liquid is a liquid containing a preservative in pure water, the cleaning liquid can be prevented from decaying. For this reason, even when the cleaning liquid is mixed with the ink in the nozzle 46, it is possible to prevent the spoiled component in the cleaning liquid from adversely affecting the ink.

  (5) After the clogging of the nozzle 46 is resolved by ejecting the clogged nozzle 46 with a mixed fluid containing a liquid for cleaning containing liquid droplets containing droplets smaller than the opening of the nozzle 46, the nozzle 46 Cleaning or flushing for discharging ink from the opening is performed. For this reason, when the mixed fluid is ejected to the clogged nozzle 46 and the clogging of the nozzle 46 is eliminated, the remaining mixed fluid is discharged by entering the liquid ejecting heads 24A and 24B from the opening of the nozzle 46. And can be removed.

(Example of change)
In addition, you may change the said embodiment as follows.
As shown in FIG. 12, instead of the external mixing type two-fluid jet nozzle 78, the cleaning liquid supplied from the liquid flow path 88a and the air supplied from the gas flow path 83a are mixed to obtain a mixed fluid. A so-called internal mixing type two-fluid injection nozzle 130 having a mixing unit KA to be generated inside may be used. In this case, the mixed fluid generated in the mixing unit KA is ejected from the ejection port 130 a provided at the tip (upper end) of the two-fluid ejection nozzle 130.

The two-fluid ejection nozzle 78 may be arranged so that the mixed fluid is ejected in the horizontal direction or obliquely upward.
A pressure pump for supplying ink in an ink tank (not shown) to the reservoir 30 is provided, and the clogged nozzle 46 during ejection of the mixed fluid from the two-fluid ejection nozzle 78 to the clogged nozzle 46 Pressurization of the ink in the pressure chamber 44 communicating with the pressure chamber 44 may be performed by the pressure pump with the differential pressure valve 31 opened.

  The ejection of the mixed fluid from the two-fluid ejection nozzle 78 to the liquid ejection heads 24A and 24B including the clogged nozzle 46 may be performed a plurality of times with a time interval. In this case, the time interval may or may not be constant. In this case, even when the mixed fluid ejected to the liquid ejecting heads 24A and 24B becomes a foam and closes the opening of the nozzle 46, the foam that closes the opening of the nozzle 46 while the ejection of the mixed fluid is stopped. The mixed fluid returns to the form of droplets. For this reason, droplets in the mixed fluid ejected later to the liquid ejecting heads 24A and 24B by the mixed fluid previously ejected to the liquid ejecting heads 24A and 24B to form bubbles and block the opening of the nozzle 46 are used. It is possible to prevent the entry into the nozzle 46 from being blocked.

  Before the mixed fluid is ejected from the two-fluid ejecting nozzle 78 to the liquid ejecting heads 24A and 24B including the nozzle 46, the cleaning liquid is ejected to the liquid ejecting heads 24A and 24B including the nozzle 46. May be. In this case, the liquid supply pump 93 may be used for jetting the cleaning liquid from the liquid jet nozzle 80, but a pump for jetting the cleaning liquid from the liquid jet nozzle 80 is provided in the middle of the liquid supply pipe 88. It is preferable to provide it. In this way, since the cleaning liquid is first ejected to the liquid ejecting heads 24A and 24B including the nozzle 46, the mixed fluid is ejected after mixing air into the cleaning liquid. Further, it is possible to suppress only air from being ejected to the liquid ejecting heads 24A and 24B including the nozzle 46. Therefore, it is possible to suppress the air ejected to the liquid ejecting heads 24A and 24B including the nozzle 46 from entering the interior of the liquid ejecting heads 24A and 24B from the opening of the nozzle 46. Further, in this case, even when the ejection of the mixed fluid to the liquid ejecting heads 24A and 24B including the nozzle 46 is stopped, the ejection of the cleaning liquid is stopped after stopping the ejection of the air first, It is possible to prevent only air from being ejected to the liquid ejecting heads 24A and 24B including the nozzle 46.

  Before the mixed fluid is ejected from the two fluid ejecting nozzles 78 to the liquid ejecting heads 24A and 24B including the nozzles 46, the cleaning liquid is ejected to the areas not including the nozzles 46 of the liquid ejecting heads 24A and 24B. You may make it do. Further, before the mixed fluid is ejected from the two-fluid ejecting nozzle 78 to the liquid ejecting heads 24A and 24B including the nozzle 46, the cleaning liquid is disposed at a position where the two-fluid ejecting nozzle 78 does not face the liquid ejecting heads 24A and 24B. May be injected. Even in this case, it is possible to prevent only air from being ejected to the liquid ejecting heads 24A and 24B including the nozzle 46.

  The cleaning liquid that is the second liquid may be composed of pure water only (pure water that does not contain preservatives). In this way, when the cleaning liquid is mixed with the ink in the nozzle 46, the cleaning liquid can be prevented from adversely affecting the ink.

  When the mixed fluid is ejected to the clogged nozzle 46, the piezoelectric element portion 37a corresponding to the clogged nozzle 46 may be driven in the same manner as during ink ejection or flushing during printing. Good. Even in this case, the mixed fluid can be prevented from entering the clogged nozzle 46.

  When ejecting the mixed fluid to the clogged nozzle 46, the nozzle 46 other than the clogged nozzle 46 is driven by driving the piezoelectric element portion 37a corresponding to the nozzle 46 other than the clogged nozzle 46. The corresponding pressure chambers 44 may be pressurized. In this way, the mixed fluid can be prevented from entering the nozzles 46 other than the clogged nozzles 46.

The two-fluid ejecting device 75 may be disposed on the home position HP side.
A wiper for wiping the nozzle forming surface 24a of the liquid ejecting heads 24A and 24B may be separately provided between the two-fluid ejecting device 75 and the printing area PA in the non-printing area NA. In this way, after the mixed fluid is ejected to the liquid ejecting heads 24A and 24B by the two-fluid ejecting device 75, the mixed fluid (for cleaning) is moved before moving the printing unit 20 to the home position HP side across the printing area PA. The nozzle forming surface 24a wetted with the liquid can be wiped with the wiper. Therefore, it is possible to prevent the mixed fluid (cleaning liquid) attached to the nozzle forming surface 24a from dripping during the movement of the printing unit 20 in the printing area PA.

  In place of the air pump 82, an air compressor of equipment such as a factory may be used. In this case, a three-way electromagnetic valve capable of opening the gas flow path 83 a to the atmosphere is provided at a position between the pressure adjustment valve 84 and the filter 85 in the gas supply pipe 83, and the gas flow when the two-fluid ejection device 75 is not used. The path 83a may be opened to the atmosphere.

  When the control unit 110 detects the nozzle 46 that does not clear the clogging even if the cleaning is performed a predetermined number of times based on the clogging detection history, the nozzle 46 that does not clear the clogging temporarily is not used. Alternatively, so-called complementary printing, in which printing is performed by ejecting ink from another normal nozzle 46, may be performed. In this case, the clogging may be eliminated by washing the nozzle 46 that is not clogged even after a predetermined number of times of cleaning after complementary printing with the two-fluid ejection device 75.

  The nozzle row 24b (nozzle 46) that ejects ink of a color (kind) that is used very infrequently is used when it comes to use without performing regular maintenance (cleaning, flushing, wiping, etc.) The clogging may be eliminated by washing with the fluid ejecting device 75. In this way, the amount of ink consumed for cleaning and flushing ink of a color (type) that is used very infrequently is reduced, so that the ink can be saved.

During the ejection of the mixed fluid from the two-fluid ejection nozzle 78 to the clogged nozzle 46, it is not always necessary to pressurize the pressure chamber 44 communicating with the clogged nozzle 46.
The product of the mass of the cleaning liquid droplet having a diameter smaller than the opening diameter of the nozzle 46 and the square of the flying speed of the droplet at the opening position of the nozzle 46 is not necessarily ejected from the opening of the nozzle 46. It is not necessary to make it larger than the product of the mass of the ink droplet and the square of the flying speed of the ink droplet.

  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.

Next, ink (colored ink) as the first liquid will be described in detail below.
The ink used for the printer 11 contains a resin and substantially does not contain glycerin having a boiling point of 290 ° C. under 1 atm. If the ink substantially contains glycerin, the drying property of the ink is greatly reduced. As a result, in various media, in particular, a non-ink-absorbing or low-absorbing medium, not only the density unevenness of the image is noticeable but also the ink fixing property cannot be obtained. Furthermore, it is preferable that the ink substantially does not contain alkyl polyols (excluding the above glycerin) having a boiling point of 280 ° C. or higher at 1 atm.

  Here, “substantially free” in the present specification means not to contain more than the amount that fully exhibits the significance of addition. Speaking quantitatively, it is preferable not to contain 1.0 mass% or more of glycerin with respect to the total mass (100 mass%) of an ink, and it is more preferable not to contain 0.5 mass% or more. More preferably, it is not contained in an amount of not less than 1% by mass, more preferably not in excess of 0.05% by mass, and particularly preferably not in excess of 0.01% by mass. And it is most preferable not to contain glycerol 0.001 mass% or more.

Next, additives (components) that are or can be included in the ink will be described.
[1. Color material]
The ink may include a color material. The color material is selected from pigments and dyes.

[1-1. Pigment]
By using a pigment as the color material, the light resistance of the ink can be improved. As the pigment, both inorganic pigments and organic pigments can be used. The inorganic pigment is not particularly limited, and examples thereof include carbon black, iron oxide, titanium oxide, and silica oxide.

  Examples of organic pigments include, but are not limited to, quinacridone pigments, quinacridone quinone pigments, dioxazine pigments, phthalocyanine pigments, anthrapyrimidine pigments, ansanthrone pigments, indanthrone pigments, flavanthrone pigments, Examples include perylene pigments, diketopyrrolopyrrole pigments, perinone pigments, quinophthalone pigments, anthraquinone pigments, thioindigo pigments, benzimidazolone pigments, isoindolinone pigments, azomethine pigments, and azo pigments. . Specific examples of the organic pigment include the following.

  Examples of pigments used for cyan ink include C.I. I. Pigment Blue 1, 2, 3, 15, 15: 1, 15: 2, 15: 3, 15: 4, 15: 6, 15:34, 16, 18, 22, 60, 65, 66, C.I. I. Bat Blue 4 and 60 are listed. Among them, C.I. I. Any one of CI Pigment Blue 15: 3 and 15: 4 is preferable.

  Examples of pigments used in magenta ink include C.I. I. Pigment Red 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 14, 15, 16, 17, 18, 19, 21, 22, 23, 30, 31, 32, 37, 38, 40, 41, 42, 48 (Ca), 48 (Mn), 57 (Ca), 57: 1, 88, 112, 114, 122, 123, 144, 146, 149, 150, 166, 168 170, 171, 175, 176, 177, 178, 179, 184, 185, 187, 202, 209, 219, 224, 245, 254, 264, C.I. I. Pigment violet 19, 23, 32, 33, 36, 38, 43, 50. Among them, C.I. I. Pigment red 122, C.I. I. Pigment red 202, and C.I. I. One or more selected from the group consisting of Pigment Violet 19 is preferred.

  Examples of pigments used in yellow ink include C.I. I. Pigment Yellow 1, 2, 3, 4, 5, 6, 7, 10, 11, 12, 13, 14, 16, 17, 24, 34, 35, 37, 53, 55, 65, 73, 74, 75, 81, 83, 93, 94, 95, 97, 98, 99, 108, 109, 110, 113, 114, 117, 120, 124, 128, 129, 133, 138, 139, 147, 151, 153, 154, 155, 167, 172, 180, 185, 213. Among them, C.I. I. One or more selected from the group consisting of CI Pigment Yellow 74, 155, and 213 are preferred.

In addition, as a pigment used for inks of colors other than the above, such as green ink and orange ink, conventionally known pigments can be used.
The average particle diameter of the pigment is preferably 250 nm or less because clogging at the nozzle 46 can be suppressed and the ejection stability is further improved. In addition, the average particle diameter in this specification is based on a volume. As a measuring method, for example, it can be measured by a particle size distribution measuring apparatus using a laser diffraction scattering method as a measurement principle. Examples of the particle size distribution measuring device include a particle size distribution meter (for example, Microtrac UPA manufactured by Nikkiso Co., Ltd.) having a dynamic light scattering method as a measurement principle.

[1-2. dye]
A dye can be used as the coloring material. The dye is not particularly limited, and acid dyes, direct dyes, reactive dyes, and basic dyes can be used. The content of the color material is preferably 0.4 to 12% by mass, and more preferably 2% by mass or more and 5% by mass or less with respect to the total mass (100% by mass) of the ink.

[2. resin]
The ink contains a resin. When the ink contains a resin, a resin film is formed on the medium. As a result, the ink is sufficiently fixed on the medium, and the effect of mainly improving the abrasion resistance of the image is exhibited. For this reason, the resin emulsion is preferably a thermoplastic resin. The heat deformation temperature of the resin is preferably 40 ° C. or higher, and is preferably 60 ° C. or higher, because the advantageous effect that the nozzle 46 is not easily clogged and the medium is rubbed is obtained. More preferred.

  Here, the “thermal deformation temperature” in the present specification is a temperature value represented by a glass transition temperature (Tg) or a minimum film forming temperature (MFT). That is, “the thermal deformation temperature is 40 ° C. or higher” means that either Tg or MFT may be 40 ° C. or higher. In addition, since MFT can grasp | ascertain the superiority or inferiority of the redispersibility of resin rather than Tg, it is preferable that the said heat deformation temperature is a temperature value represented by MFT. If the ink is excellent in resin redispersibility, the ink does not adhere and the nozzle 46 is less likely to be clogged.

  Although it does not specifically limit as a specific example of the said thermoplastic resin, Poly (meth) acrylic acid ester or its copolymer, polyacrylonitrile or its copolymer, polycyanoacrylate, polyacrylamide, poly (meth) acrylic acid, etc. (Meth) acrylic polymers, polyethylene, polypropylene, polybutene, polyisobutylene, and polystyrene, and copolymers thereof, and polyolefin polymers such as petroleum resins, coumarone-indene resins, and terpene resins, polyvinyl acetate Or copolymers thereof, vinyl acetate-based or vinyl alcohol-based polymers such as polyvinyl alcohol, polyvinyl acetal, and polyvinyl ether, polyvinyl chloride or copolymers thereof, polyvinylidene chloride, fluororesin, and fluorine-containing halogenated compounds such as fluororubber. -Based polymers, polyvinylcarbazole, polyvinylpyrrolidone or copolymers thereof, nitrogen-containing vinyl polymers such as polyvinylpyridine and polyvinylimidazole, polybutadienes or copolymers thereof, polychloroprene, and diene systems such as polyisoprene (butyl rubber) Examples include polymers, and other ring-opening polymerization resins, condensation polymerization resins, and natural polymer resins.

  The content of the resin is preferably 1 to 30% by mass, and more preferably 1 to 5% by mass with respect to the total mass (100% by mass) of the ink. When content is in the said range, the glossiness and abrasion resistance of the top coat image formed can be made further excellent. Examples of the resin that may be contained in the ink include a resin dispersant, a resin emulsion, and a wax.

[2-1. Resin emulsion]
The ink may contain a resin emulsion. When the medium is heated, the resin emulsion preferably forms a resin film together with the wax (emulsion), thereby exhibiting an effect of sufficiently fixing the ink on the medium and improving the abrasion resistance of the image. When the medium is printed with the ink containing the resin emulsion due to the above-described effect, the ink has excellent abrasion resistance particularly on a non-ink-absorbing or low-absorbing medium.

  The resin emulsion that functions as a binder is contained in the ink in an emulsion state. By including a resin functioning as a binder in the ink in an emulsion state, the viscosity of the ink can be easily adjusted to an appropriate range in the ink jet recording system, and the storage stability and ejection stability of the ink can be improved.

  Examples of the resin emulsion include, but are not limited to, (meth) acrylic acid, (meth) acrylic acid ester, acrylonitrile, cyanoacrylate, acrylamide, olefin, styrene, vinyl acetate, vinyl chloride, vinyl alcohol, vinyl ether, vinyl pyrrolidone. , Vinyl pyridine, vinyl carbazole, vinyl imidazole, and vinylidene chloride homopolymers or copolymers, fluororesins, and natural resins. Among them, either a methacrylic resin or a styrene-methacrylic acid copolymer resin is preferable, either an acrylic resin or a styrene-acrylic acid copolymer resin is more preferable, and a styrene-acrylic acid copolymer resin is more preferable. Even more preferred. In addition, said copolymer may be any form among a random copolymer, a block copolymer, an alternating copolymer, and a graft copolymer.

  The average particle diameter of the resin emulsion is preferably in the range of 5 nm to 400 nm, and more preferably in the range of 20 nm to 300 nm, in order to further improve the storage stability and ejection stability of the ink. Among the resins, the content of the resin emulsion is preferably in the range of 0.5 to 7% by mass with respect to the total mass (100% by mass) of the ink. When the content is within the above range, the solid content concentration can be lowered, so that the discharge stability can be further improved.

[2-2. wax]
The ink may include wax. When the ink contains a wax, the fixability of the ink on a non-ink-absorbing and low-absorbing medium is further improved. Among them, an emulsion type is more preferable. Examples of the wax include, but are not limited to, polyethylene wax, paraffin wax, and polyolefin wax. Among them, polyethylene wax described later is preferable. In the present specification, the “wax” means a product in which solid wax particles are dispersed in water mainly using a surfactant described later.

  When the ink contains polyethylene wax, the ink can have excellent abrasion resistance. The average particle diameter of the polyethylene wax is preferably in the range of 5 nm to 400 nm, and more preferably in the range of 50 nm to 200 nm, in order to further improve the storage stability and ejection stability of the ink.

  The polyethylene wax content (in terms of solid content) is preferably in the range of 0.1 to 3% by mass, independently of the total mass (100% by mass) of the ink, and 0.3 to 3%. The range is more preferably in the range of mass%, and further preferably in the range of 0.3 to 1.5 mass%. When the content is within the above range, the ink can be solidified and fixed satisfactorily even on a non-ink-absorbing or low-absorbing medium, and the storage stability and ejection stability of the ink are further improved. Can be.

[3. Surfactant]
The ink may contain a surfactant. Examples of the surfactant include, but are not limited to, nonionic surfactants. The nonionic surfactant has an action of spreading the ink uniformly on the medium. For this reason, when printing is performed using an ink containing a nonionic surfactant, a high-definition image with almost no bleeding is obtained. Examples of such nonionic surfactants include, but are not limited to, silicon-based, polyoxyethylene alkyl ether-based, polyoxypropylene alkyl ether-based, polycyclic phenyl ether-based, sorbitan derivatives, and fluorine-based interfaces. Examples of the surfactant include silicon surfactants.

  The content of the surfactant is that the storage stability and ejection stability of the ink are further improved. A range is preferable.

[4. Organic solvent]
The ink may contain a known volatile water-soluble organic solvent. However, as described above, the ink contains substantially no glycerin (boiling point at 290 ° C. under 1 atm), which is a kind of organic solvent, and alkyl polyols having a boiling point of 280 ° C. or more under 1 atm. It is preferable that it does not contain substantially (except the said glycerol).

[5. Aprotic polar solvent]
The ink may include an aprotic polar solvent. By containing the aprotic polar solvent in the ink, the above-described resin particles contained in the ink are dissolved, so that clogging of the nozzle 46 can be effectively suppressed during printing. Further, since it has a property of dissolving a medium such as vinyl chloride, image adhesion is improved.

  The aprotic polar solvent is not particularly limited, but one or more selected from pyrrolidones, lactones, sulfoxides, imidazolidinones, sulfolanes, urea derivatives, dialkylamides, cyclic ethers, amide ethers It is preferable to contain. Representative examples of pyrrolidones include 2-pyrrolidone, N-methyl-2-pyrrolidone, and N-ethyl-2-pyrrolidone. Representative examples of lactones include γ-butyrolactone, γ-valerolactone, and ε-caprolactone. Typical examples of sulfoxides include dimethyl sulfoxide and tetramethylene sulfoxide.

  Typical examples of imidazolidinones include 1,3-dimethyl-2-imidazolidinone, typical examples of sulfolanes include sulfolane and dimethylsulfolane, and typical examples of urea derivatives include dimethylurea, There is 1,1,3,3-tetramethylurea. Representative examples of dialkylamides include dimethylformamide and dimethylacetamide, and representative examples of cyclic ethers include 1,4-dioxane and tetrahydrofuran.

  Among these, pyrrolidones, lactones, sulfoxides, and amide ethers are particularly preferable from the viewpoint of the effects described above, and 2-pyrrolidone is most preferable. The content of the aprotic polar solvent is preferably in the range of 3 to 30% by mass and more preferably in the range of 8 to 20% by mass with respect to the total mass (100% by mass) of the ink. preferable.

[6. Other ingredients]
The ink may further contain a fungicide, a rust inhibitor, a chelating agent, and the like in addition to the above components.

  DESCRIPTION OF SYMBOLS 11 ... Printer as an example of liquid ejecting apparatus, 24A, 24B ... Liquid ejecting head as an example of liquid ejecting part, 37 ... Piezoelectric element as an example of actuator, 44 ... Pressure chamber, 46 ... Nozzle, 75 ... Two fluid ejecting Device, ST ... sheet as an example of medium.

Claims (8)

A liquid ejecting section capable of ejecting the first liquid from the nozzle opening to the medium;
A two-fluid ejection device capable of ejecting at least one of a gas and a second liquid with respect to the liquid ejection section;
The two-fluid ejecting device includes the liquid ejecting unit including the nozzle as a mixed fluid in which the second liquid in the form of droplets including droplets smaller than the opening of the nozzle of the liquid ejecting unit is mixed with the gas. and injection against,
The product of the mass of the droplet of the second liquid that is smaller than the opening of the nozzle and the square of the flying speed of the droplet at the opening position of the nozzle is the product of the first liquid ejected from the opening of the nozzle. A liquid ejecting apparatus, wherein the liquid ejecting apparatus is larger than a product of a mass of the droplet and a square of a flying speed of the droplet . The two-fluid ejection device, in a state in which the first liquid in the liquid ejecting portion is pressurized, to claim 1, characterized by injecting the mixed fluid with respect to the liquid ejecting portion including the nozzle The liquid ejecting apparatus described. The liquid ejecting section includes a pressure chamber communicating with the nozzle, and an actuator capable of pressurizing the pressure chamber.
The two-fluid ejecting device ejects the mixed fluid to the liquid ejecting unit including the nozzle in a state where the first liquid in the pressure chamber is pressurized by driving the actuator. The liquid ejecting apparatus according to claim 2 . The second liquid to a liquid ejecting apparatus as claimed in any one of claims 1 to 3, characterized in that pure water or pure water as a liquid containing a preservative. A liquid ejecting section capable of ejecting the first liquid from the nozzle opening to the medium;
A maintenance method for a liquid ejecting apparatus, comprising a two-fluid ejecting apparatus capable of ejecting at least one of a gas and a second liquid with respect to the liquid ejecting unit,
After ejecting the second liquid from the two-fluid ejecting device, the second liquid in the form of droplets containing droplets smaller than the opening of the nozzle of the liquid ejecting unit with respect to the liquid ejecting unit including the nozzle. maintenance method of the mixed fluid obtained by mixing with the liquid gas liquid-jet apparatus characterized Rukoto pointed injection from the two-fluid ejection device. 6. The maintenance method for a liquid ejecting apparatus according to claim 5, wherein after the ejection of the mixed fluid, the first liquid is discharged from an opening of the nozzle. 7. The maintenance method for a liquid ejecting apparatus according to claim 5 , wherein the ejection of the mixed fluid is performed a plurality of times at time intervals. Before performing the injection of the mixed fluid, of the claims 5 to claim 7, characterized in that the injection of the second fluid from the second fluid ejection device relative to the liquid ejecting portion including the nozzle The maintenance method of the liquid ejecting apparatus according to any one of the above.