JP2018149461A - Inkjet printing device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an inkjet printing device which can easily remove stains of a cap of an inkjet head.SOLUTION: An inkjet printing device includes: an inkjet head 31 having a nozzle discharging ink; two or more caps 50 which are abutted to the inkjet head 31 and cover the nozzle; a cap base 52 which holds the two or more caps 50 on the outer peripheral surface and is rotatable with an axis parallel to an array direction of the nozzle as a center; a cleaning liquid tank 47 storing a cleaning liquid; a driving section 59 rotating the cap base; and a control section 5 which drives the driving section 59 and controls a positional relationship among the inkjet head 31, the cap 50 and the cleaning liquid tank 47 so that in a stand-by state when a nozzle surface of the inkjet head 31 is sealed by one of the two or more caps 50, at least one of the other caps 50 is immersed in the cleaning liquid of the cleaning liquid tank 47.SELECTED DRAWING: Figure 3

Description

  The present invention relates to an ink jet printing apparatus that prints by discharging ink from an ink jet head onto a print medium.

  In the ink jet printing apparatus, a cap capable of sealing the nozzle surface is provided to prevent the ink on the nozzle surface of the ink jet head from drying. In addition, when it is assumed that it will not be used for a long period of time, fill cap control is performed such that the nozzle surface of the ink jet head is covered with a cap to create a sealed state, and the cap is filled with ink. .

  As a technique for covering with a cap in order to prevent the inkjet head from drying, for example, there is one disclosed in Patent Document 1. The technique of Patent Document 1 uses a plurality of ribs that come into contact with the face surface of the ink jet recording head of the cap in order to prevent the drying prevention capability from being lowered due to the displacement of the cap of the capping device.

JP 7-125243 A

  If the inside of the cap is not sufficiently cleaned, the ink may stick to the inside of the cap, particularly to the edge portion.

  In addition, when the ink cap is left for a long period of time after performing the fill cap control, the thin-film ink may stick to the portion where the nozzle plate, which is the ejection surface of the inkjet head, and the cap are in close contact.

These fixed inks may not be completely removed even if they are manually cleaned or automatically washed, resulting in poor sealing when capping the inkjet head and drying the nozzle surface. In some cases, it could not be sufficiently suppressed.

  The present invention has been made in view of the above, and an object of the present invention is to provide an inkjet printing apparatus that can easily remove dirt inside the cap of an inkjet head.

  In order to achieve the above object, a first feature of an ink jet printing apparatus according to the present invention is an ink jet head having a nozzle for ejecting ink, two or more caps that contact the ink jet head and cover the nozzle, A cap base that holds the cap on the outer peripheral surface and is rotatable about an axis parallel to the arrangement direction of the nozzles, a cleaning liquid tank that stores cleaning liquid, and a drive unit that rotates the cap base; In a standby state in which the driving unit is driven and the nozzle surface of the inkjet head is sealed with one of the two or more caps, at least one of the other caps is immersed in the cleaning liquid in the cleaning liquid tank. A controller that controls the positional relationship between the inkjet head, the cap, and the cleaning liquid tank so as to be in a state. In the Rukoto.

  A second feature of the ink jet printing apparatus according to the present invention is that, when the control unit shifts to the standby state, the cap time in which the ink jet head is covered with the cap continues longer than a predetermined time. When it is determined that the cap has been used, the drive unit is controlled so that the cap is immersed in the cleaning liquid tank.

  According to the first feature of the inkjet printing apparatus according to the present invention, when the inkjet head is capped with the cap, the other cap is immersed in the cleaning liquid. Therefore, even if ink that could not be removed remains in the cap, the remaining dirt can be easily removed at the next manual cleaning by the user or automatic cleaning by the apparatus. Thereby, the cap used for capping can be kept cleaner than before, and the drying of the nozzle due to capping failure can be suppressed.

  According to the second feature of the inkjet printing apparatus according to the present invention, the cap that has been in the capping state for a long time is not used for capping the inkjet head at the next capping. Further, the cap that has been in the capping state for a long time while capping with another cap is transferred to the standby state while being immersed in the cleaning liquid. Thereby, in addition to the effect of the first feature, even if dirt remains in the cap in the previous cleaning (washing), the dirt can be easily removed at the next cleaning (washing).

1 is an overall perspective view of an inkjet printing apparatus according to an embodiment. It is a front view which shows typically schematic structure of an inkjet printing apparatus. It is a schematic block diagram of the cap mechanism part of an inkjet printing apparatus. It is a figure which shows the capping state by a cap, and the immersion state in a washing | cleaning liquid. It is an abbreviated perspective view of the principal part of a cap mechanism part. It is a control block diagram of an inkjet printing apparatus. It is a flowchart for demonstrating operation | movement of this embodiment.

  Embodiments of the present invention will be described below with reference to the drawings. Throughout the drawings, the same or equivalent parts and components are denoted by the same or equivalent reference numerals.

  The following embodiments exemplify devices for embodying the technical idea of the present invention, and the technical idea of the present invention is the material, shape, structure, arrangement, etc. of each component. Is not specified as follows. The technical idea of the present invention can be variously modified within the scope of the claims.

  FIG. 1 is an overall perspective view of the ink jet printing apparatus. FIG. 2 is a front view schematically showing a schematic configuration of the ink jet printing apparatus. FIG. 3 is a schematic configuration diagram of a cap mechanism unit of the inkjet printing apparatus. FIG. 4 is a diagram illustrating a capping state using a cap and a state immersed in a cleaning liquid. FIG. 5 is an abbreviated perspective view of the main part of the cap mechanism. FIG. 6 is a control block diagram of the ink jet printing apparatus. In the following description, the vertical and horizontal directions indicated by the arrows in FIG.

  As shown in FIGS. 1, 2, and 6, the inkjet printing apparatus 1 according to the present embodiment includes a shuttle base unit 2, a flat bed unit 3, a shuttle unit 4, a control unit 5, and a timer 6. Prepare.

  The shuttle base unit 2 supports the shuttle unit 4 and moves the shuttle unit 4 in the front-rear direction (sub-scanning direction). The shuttle base unit 2 includes a gantry 11 and a sub-scanning drive motor 12.

  The gantry 11 supports the shuttle unit 4. The gantry 11 is formed in a rectangular frame shape. Sub-scanning drive guides 13A and 13B extending in the front-rear direction are formed on the left and right frames of the gantry unit 11, respectively. The sub-scanning drive guides 13A and 13B guide the shuttle unit 4 to move in the front-rear direction.

  The sub-scanning drive motor 12 moves the shuttle unit 4 in the front-rear direction.

  The flat bed unit 3 holds a print medium 15 made of a base material such as a building material or a decorative panel. The flat bed unit 3 is disposed inside the gantry 11 of the shuttle base unit 2. The flat bed unit 3 has a medium placement surface 3a that is a horizontal surface on which the print medium 15 is placed. The flat bed unit 3 can adjust the height of the medium placement surface 3a by an elevating mechanism such as a hydraulic drive mechanism.

  The shuttle unit 4 prints an image on the print medium 15. As shown in FIGS. 1, 2, and 6, the shuttle unit 4 includes a housing 21, a main scanning drive guide 22, a main scanning drive motor 23, a head lifting guide 24, a head lifting motor 25, and a head. The unit 26, the cap mechanism part 27, and the wipe part 28 are provided.

  The housing 21 houses each part such as the head unit 26. The casing 21 is formed in a gate shape straddling the flat bed unit 3 in the left-right direction. The casing 21 is supported by the gantry 11 of the shuttle base unit 2 and is movable along the sub-scanning drive guides 13A and 13B.

  The main scanning drive guide 22 guides the head unit 26 to move in the left-right direction (main scanning direction). The main scanning drive guide 22 is formed in a long shape extending in the left-right direction.

  The main scanning drive motor 23 moves the head unit 26 in the left-right direction.

  The head lifting guide 24 guides the head unit 26 to move in the vertical direction. The head lifting guide 24 is formed in an elongated shape in the vertical direction. The head raising / lowering guide 24 is configured to be movable in the left-right direction along the main scanning drive guide 22 together with the head unit 26.

  The head lifting motor 25 moves the head unit 26 up and down.

  The head unit 26 prints an image by ejecting ink onto the print medium 15 while moving in the left-right direction along the main scanning drive guide 22. The head unit 26 includes four inkjet heads 31.

  The inkjet head 31 discharges aqueous ink to the print medium 15. The four inkjet heads 31 are arranged in parallel in the left-right direction. The four inkjet heads 31 eject inks of different colors (for example, cyan, black, magenta, and yellow). The inkjet head 31 has a plurality of nozzles (not shown) that are open on the ejection surface 31a that is the lower surface thereof, and ejects ink from the nozzles. The plurality of nozzles are arranged along the front-rear direction.

  The cap mechanism unit 27 covers the nozzles of the inkjet head 31 and performs capping with a space where the nozzles are opened as a closed space. The cap mechanism portion 27 is disposed inside the right end portion of the housing 21. As shown in FIGS. 2 to 5, the cap mechanism unit 27 includes four cap units 41, four pumps 42, four atmospheric release valves 43, a waste liquid tank 44, a cap lifting / lowering motor 45, and a cap rotation. A drive unit 46 and a cleaning liquid tank 47 are provided. Note that, in FIG. 3, the configuration corresponding to one inkjet head 31 is shown as a representative of the portions having the same configuration provided corresponding to each inkjet head 31. Further, in FIG. 5, the cap 50a provided on the first surface of the cap base 52 and the cap 50b provided on the second surface are the same, and therefore the parts having the same configuration related thereto are representative. The structure corresponding to one cap 50a is shown.

  The cap unit 41 includes caps 50 a and 50 b, a cap base 52, a suction pipe 53, an air release pipe 54, and a worm 55. The cap base 52 includes caps 50a and 50b having the same shape on the front and back surfaces, respectively. It should be noted that a plurality of caps 50 may be formed around the cap base 52 without being limited to the front and back sides.

  The caps 50a and 50b are members that come into contact with the ejection surface 31a of the inkjet head 31 and perform capping.

The cap 50 a includes an ellipse-shaped ink receiving surface 56 that is a bottom portion, and a peripheral wall 57 erected on the periphery of the ink receiving surface 56. The ink receiving surface 56 is provided with a suction hole 56a1 for sucking air, ink and the like from the space in the cap 51, and an air release hole 56a2 for opening the space in the cap 51 to the atmosphere. The peripheral wall 57 is formed in a shape that surrounds all the nozzles when contacting the ejection surface 31 a of the inkjet head 31. The end on the opening side opposite to the ink receiving surface 56 side of the peripheral wall 57 forms the opening end 51a of the cap 50a.

A plurality of caps 50 are provided on the outer peripheral surface of the cap base. In this embodiment, two caps 50a and 50b are provided as shown in FIGS. 3 and 4, and 50a and 50b have the same shape.

  The cap base 52 has a front surface 52a and a back surface 52b parallel to the ejection surface 31a of the inkjet head 31, and holds caps 50a and 50b on the front surface 52a side and the back surface 52b side, respectively.

  By rotating the cap base 52 by the cap rotation driving unit 46 and reversing the front and back, the control unit 5 controls the caps 50 a and 50 b to selectively face the ejection surface 31 a of the inkjet head 31.

  The suction pipe 53 constitutes a flow path for air, ink, and the like sucked from the spaces in the caps 50a and 50b. One end of the suction pipe 53 is connected to the waste liquid tank 44. Further, the other end of the suction pipe 53 is branched into two on the cap 50 a side from the pump 42. One end of the two branched pipes of the suction pipe 53 is connected to the suction hole 56a1 of the cap 50a having the opening end 51a, and the other end is connected to the suction hole 56b1 of the cap 50b having the opening end 51b. .

Further, a valve 71A and a valve 71B are arranged on the branched pipe of the suction pipe 53, respectively. The valve 71A is disposed between the branch point of the suction pipe 53 and the suction hole 56a1 of the cap 50a having the opening end 51a, and opens and closes the flow path in the suction pipe 53 in that section. The valve 71B is disposed between the branch point of the suction pipe 53 and the suction hole 56b1 of the cap 50b having the opening end 51b, and opens and closes the flow path in the suction pipe 53 in the section.

  The atmosphere release pipe 54 constitutes an air flow path for communicating the space in the cap 50a from the ink receiving surface 56 side to the atmosphere. An atmosphere release valve 43 is connected to one end (atmosphere release end) of the atmosphere release pipe 54. The other end on the cap 50a side of the atmosphere release pipe 54 has a single pipe branched in the middle, and air for communicating the spaces in the caps 50a and 50b from the ink receiving surface 56 side to the atmosphere. Are connected to an air release hole 56a2 provided in the ink receiving surface 56 on the cap 50a side and an air release hole 56b2 provided in the ink receiving surface 56 on the cap 50b side.

Further, a valve 72A and a valve 72B are arranged on the branched pipes of the atmosphere release pipe 54, respectively. The valve 72A is disposed between the branch point of the atmosphere release pipe 54 and the atmosphere release hole 56a2 of the cap 50a, and opens and closes the flow path in the atmosphere release pipe 54 in that section. The valve 72B is disposed between the branch point of the atmosphere release pipe 54 and the atmosphere release hole 56b2 of the cap 50b, and opens and closes the flow path in the atmosphere release pipe 54 in that section.

Although the suction hole 56b1 and the air release hole 56b2 are not shown, they are provided at the same location as the suction hole 56a1 and the air release hole 56a2 with the cap base 52 interposed therebetween.

The worm 55 is rotated by the driving force of the cap rotation driving unit 46 to rotate the cap base 52 about the front-rear direction. The worm 55 is fixed to the front end of the cap base 52.

The pump 42 is for sucking contents such as air and ink from the spaces in the caps 50a and 50b. The pump 42 is configured to be capable of forward and reverse rotation. The pump 42 is installed in the middle of the suction pipe 53. That is, the pump 42 is connected to the suction holes 56a1 and the suction holes 56b1 of the caps 50a and 50b via the suction pipe 53.

  The atmosphere release valve 43 opens and closes the opening at the atmosphere release end of the atmosphere release pipe 54. When the atmosphere release valve 43 is in the open state, the atmosphere release pipe 54 communicates with the atmosphere from the atmosphere release end via the suction hole 56a2 or the suction hole 56b2 on the side where the valve 72A or the valve 72B is opened. When is closed, the atmosphere release pipe 54 is blocked from the atmosphere at the atmosphere release end.

  The waste liquid tank 44 stores ink or the like sent by the pump 42 via the suction pipe 53 as waste liquid.

  The cap lifting / lowering motor 45 moves the four cap units 41 and the cap rotation driving unit 46 up and down.

  The cap rotation drive unit 46 rotates the cap base 52 by rotating the worm 55. The cap rotation drive unit 46 includes four worm wheels 58 and a cap rotation motor 59.

  The worm wheel 58 meshes with the worm 55 and rotates around a rotation shaft (not shown) extending in the left-right direction, thereby rotating the worm 55. One worm wheel 58 is disposed in each of the four cap units 41. Four worm wheels 58 are fixed to a common rotating shaft.

  The cap rotation motor 59 rotates the rotation shaft of the worm wheel 58.

  The cleaning liquid tank 47 stores a cleaning liquid for cleaning the caps 50a and 50b. The cleaning liquid tank 47 is disposed below the cap base 52.

  The controller 5 immerses the caps 50 and 50 b in the cleaning liquid tank 47, and after capping the inkjet head 31 with either the cap 50 a or 50 b, the head unit 26 and the cap are moved by the head lifting motor 25 and the cap lifting motor 45. The unit 41 is lowered by the same distance. As a result, either the other cap 50a or 50b that is not used for capping reaches the cleaning liquid tank 47 and is immersed while the inkjet 31 and either of the caps 50a or 50b are kept sealed. In this state, since the other cap 50 is immersed in the cleaning liquid in the cleaning liquid tank 47 while the inkjet head 31 is capped with one cap 50, the immersed cap 50 is cleaned or cleaned next time. In this case, the dirt inside the cap can be easily removed.

  The cleaning liquid has a function of dissolving ink. As this cleaning liquid, for example, an aqueous solvent containing water and a surfactant can be used.

  Examples of the surfactant include fatty acid sodium, sodium alkylbenzene sulfonate, sodium alkyl sulfonate, sodium α-olefin sulfonate, sodium alkyl sulfate ester, sodium alkyl ether sulfate ester, sodium α-sulfo fatty acid ester, sodium alkyl phosphate ester. Anionic surfactant such as alkyl cationic trimethylammonium, dialkyldimethylammonium, etc .; sorbitan fatty acid ester, polyoxyethylene sorbitan fatty acid ester, sucrose fatty acid ester, polyoxyethylene alkyl ether, polyoxyethylene alkyl Nonionic surfactants such as phenyl ethers; sodium alkylamino fatty acids, alkylbetaines, alkylamines Amphoteric surfactants such as oxide can be used. In addition, polymer surfactants, silicone surfactants, fluorine surfactants, acetylene glycol surfactants, and the like can also be used. Among these, it is preferable to use polyoxyethylene alkyl ether, the HLB value is 11 to 17, the number of carbon atoms of the alkyl group is 8 to 15, and the number of added moles of ethylene oxide is more preferably 6 to 25.

  The cleaning liquid preferably further contains a thickener. As the thickener, a water-soluble polymer thickener or a clay mineral thickener can be used. As the water-soluble polymer thickener, natural polymers, semi-synthetic polymers, and synthetic polymers can be used. Examples of natural polymers include plant-based natural polymers such as gum arabic, carrageenan, guar gum, locust bean gum, pectin, tragacanth gum, corn starch, konjac mannan, agar; Animal-based natural polymers such as gelatin, casein, and glue can be used. Examples of semi-synthetic polymers include cellulose-based semi-synthetic polymers such as ethyl cellulose, carboxymethyl cellulose, hydroxyethyl cellulose, hydroxypropyl cellulose, methyl cellulose, and hydroxypropyl methyl cellulose; starch-based compounds such as hydroxyethyl starch, sodium carboxymethyl starch, and cyclodextrin. Semi-synthetic polymers; Alginate-based semi-synthetic polymers such as sodium alginate and propylene glycol alginate; sodium hyaluronate can be used. As the synthetic polymer, for example, vinyl-based synthetic polymers such as polyvinyl pyrrolidone, polyvinyl alcohol, polyvinyl methyl ether, poly N-vinylacetamide, and polyacrylamide; polyethylene oxide, polyethyleneimine, and polyurethane can be used. As the clay mineral-based thickener, for example, smectite-based clay minerals such as montmorillonite, hectorite, and saponite can be used. Among these, it is preferable to use hydroxypropyl methylcellulose.

  Furthermore, in addition to the above components, the cleaning liquid can optionally contain a water-soluble organic solvent, a pH adjuster, an antioxidant, a preservative, and the like. The viscosity of the cleaning liquid is preferably 5 to 200 mPa · s at 23 ° C., and more preferably 10 to 100 mPa · s.

  The wipe unit 28 wipes the ejection surface 31 a of the inkjet head 31 during maintenance of the inkjet head 31. The wipe unit 28 is disposed inside the left end portion of the housing 21. The wipe unit 28 includes four wipers 61 and a wiper drive unit 62.

  The wiper 61 is a member that wipes the ejection surface 31 a of the inkjet head 31. The wiper 61 is made of a material such as elastically deformable rubber.

  The wiper drive unit 62 moves the four wipers 61 in the front-rear direction. The wiper drive unit 62 has a motor or the like (not shown).

  The control unit 5 controls the operation of the entire inkjet printing apparatus 1. The control unit 5 includes a CPU, a RAM, a ROM, a hard disk, and the like.

  The control unit 5 rotates the cap base 52 by the cap rotation driving unit 46 so that a desired cap of the cap 50 faces the cleaning liquid tank 47 and the inkjet head 31. Further, the control unit 5 drives the head lifting motor 25 and the cap lifting motor 45 to control the relative positional relationship among the inkjet head 31, the cap 50, and the cleaning liquid tank 47.

In addition, when the cap 50 is to be cleaned, the control unit 5 drives the pump 42 with the cap 50a immersed in the cleaning liquid and sucks the cleaning liquid from the suction hole 56a1 when the cap 50 is cleaned. Then, the pump 42 is driven reversely to the time of suction, and the cleaning liquid sucked into the suction pipe 53 is controlled to be discharged from the suction hole 56a1. If the object to be cleaned is the cap 50b, the 50b is cleaned using the suction hole 56b1 with the cap 50a immersed in the cleaning liquid.

At this time, the controller 5 opens the valve 71A and the valve 71B connected to the cap 50 to be cleaned, and closes the one connected to the cap 50 to be closed. Controls the opening and closing of.

The timer 6 measures time. The control unit 5 acquires the time from the timer 6 as necessary, and stores a necessary one of the acquired values in a storage medium such as a hard disk.
<Printing action>

Next, the printing operation of the inkjet printing apparatus 1 will be described with reference to FIG.

In the inkjet printing apparatus 1, the shuttle unit 4 is disposed at the standby position in the standby state before the start of the printing operation. The standby position of the shuttle unit 4 is the position of the shuttle unit 4 shown by a solid line in FIG. 1, and is at the rear end of the gantry 11 of the shuttle base unit 2.

  Further, in the standby state of the inkjet printing apparatus 1, the head unit 26 is disposed at a home position away from the printing start position. In this state, the inkjet head 31 is capped by either the cap 50 a or 50 b, and the other cap 50 is immersed in the cleaning liquid in the cleaning liquid tank 47.

  When the printing process is started, the control unit 5 drives the head lifting motor 25 to release capping between the inkjet head 31 and the cap 50a. Here, description will be made assuming that capping is performed by the cap 50a. Moreover, before performing the subsequent steps, the control unit 5 performs a cap cleaning operation described later.

Next, the control unit 5 controls the sub-scanning drive motor 12 to move the shuttle unit 4 from the standby position to the print processing start position. The printing process start position of the shuttle unit 4 is the position of the shuttle unit 4 indicated by a two-dot chain line in FIG. 1 and is at the front end of the gantry 11 of the shuttle base unit 2. Prior to the input of the print job, the print medium 15 is placed on the medium placement surface 3 a of the flat bed unit 3.

  At this time, the control unit 5 capping the inkjet head 31 until just before by driving the cap lifting motor 45 and the cap rotation motor 59 in parallel with the process of moving to the printing process start position (step S1). The cap 50a that has been used is immersed in the cleaning liquid tank 47, and a cap cleaning operation described later is executed (step S2).

  Further, the control unit 5 obtains the current time from the timer 6 and the capping start time stored in a storage medium such as an HDD, and the time during which the cap 50a is in a standby state (hereinafter referred to as cap time). Obtain (step S3).

Next, the control unit 5 controls the main scanning drive motor 23 to move the head unit 26 in the main scanning direction, and controls the ink jet head 31 based on the print job to discharge ink from the nozzles, thereby causing one pass. Print minutes. Next, the control unit 5 controls the sub-scanning drive motor 12 to move the shuttle unit 4 backward to the printing position of the next pass. The control unit 5 alternately performs the printing for one pass and the movement of the shuttle unit 4, thereby forming an image on the printing medium 15 and executing the printing process (step S4).

  When printing for one sheet is completed (step S5: Yes), the control unit 5 controls the main scanning drive motor 23 to place the head unit 26 at the home position.

And the control part 5 judges whether the cap time acquired in step S3 was longer than predetermined time (step S6). When the cap time is longer than the predetermined time (step S6: Yes), dirt inside the cap 50a may not be completely removed even if a cap cleaning process described later is executed. If the dirt is left unattended, the contact state cannot be secured even if the capping process is performed, and drying of the nozzle surface of the inkjet head 31 may not be suppressed. Therefore, in order to facilitate the removal of dirt, the control unit 5 determines in step 6 whether or not it is necessary to continue the state in which the cap 50a that has capped the inkjet head 31 immediately before is immersed in the cleaning liquid tank 47. To do.

When the control unit 5 determines that step S6 is Yes, the control unit 5 controls the cap rotation motor 59 so that the cap 50a is immersed in the cleaning liquid tank 47 in the standby state, and the cap 50a and the cleaning liquid tank 47. Face each other. Then, the controller 5 drives the cap lifting / lowering motor 45 to move the cap unit 41 upward and bring the cap 50 b facing the inkjet head 31 into contact. Thereafter, the controller 5 drives the head lifting motor 25 and the cap lifting motor 45 by the same distance to lower both the head unit 26 and the cap unit 41, and continues the state in which the cap 50a is immersed in the cleaning liquid tank 47. (Step S7).

  If it is determined No in step S6, the inkjet head 31 may be capped with any cap 50 (step S8). The caps 50a and 50b may be used alternately. Further, as in step 7 above, in the standby state, the control unit 5 is configured so that the inkjet head 31 is capped with one cap and the other cap is immersed in the cleaning liquid in the cleaning liquid tank 47. The lift motor 25 and the cap lift motor 45 are driven to control the positional relationship between the inkjet head 31, the caps 50a and 50b, and the cleaning liquid tank 47.

  Thereafter, when the control unit 5 determines that the capping state of S7 or S8 is continued for a long time, the control unit 5 performs fill cap control to prevent the nozzle surface from drying. For example, the case where the control unit 5 has not received a print job is longer than a predetermined time, or the apparatus is turned off.

In addition, the control unit 5 stores the time of capping in Step 7 or Step 8 or the time of performing the fill cap control in a storage medium such as hardware. In the next printing operation, the control unit 5 uses this time information for the determination in step S6.
<Cap cleaning operation>

Next, a cap cleaning operation (also referred to as a cap cleaning process) in the inkjet printing apparatus 1 will be described.

The cap cleaning operation is performed following the release of the fill cap state when the inkjet printing apparatus 1 is turned on when the unprinted state continues for a long period of time.
When the power of the inkjet printing apparatus 1 is turned on, the control unit 5 opens the air release valve 43, opens the valve 71A, drives the pump 42, and the cap that has been in the capping state until immediately before is opened. The ink in the space in 50a is discharged from the suction hole 56a1. When the discharge of the ink in the space in the cap 51 is completed, the fill cap state is released.

  When the fill cap state is released, the controller 5 starts a cap cleaning operation.

  The cap cleaning operation will be specifically described. The control unit 5 controls the cap lifting motor 45 to move the cap unit 41 from the capping position to the retracted position. Here, the retreat position of the cap unit 41 is a position immediately above the cleaning liquid tank 47. When the cap base 52 is rotated and turned upside down, the cap 50a that has been in the fill cap state until just before is used as the cleaning liquid in the cleaning liquid tank 47. It is in a position where it can be immersed.

  Next, the control unit 5 controls the cap rotation motor 59 to rotate the cap base 52 and then immerses the cap 50 a in the cleaning liquid in the cleaning liquid tank 47. Specifically, the control unit 5 controls the cap rotation motor 59 to rotate the cap base 52 by 180 °. As a result, the cap base 52 is in a state where the surface 52a faces downward.

Next, the controller 5 drives the cap lifting / lowering motor 45 to lower the cap unit 41 until the cap 50a that has been capped immediately before is immersed in the cleaning liquid in the cleaning liquid tank 47. At this time, at least the opening end 51a of the cap 50a may be immersed in the cleaning liquid.

  Next, after the air release valve 43 is closed, the control unit 5 opens the valve 71A and drives the pump 42 to suck the cleaning liquid from the suction hole 56a1 into the suction pipe 53.

  Next, the control unit 5 drives the pump 42 in the reverse direction to the time of suction in step S3 to discharge the cleaning liquid sucked into the suction pipe 53 from the suction hole 56a1. Thereafter, the control unit 5 opens the atmosphere release valve 43.

  The control unit 5 maintains the state immersed in the cleaning liquid tank 47. As a result, the cap cleaning operation is completed.

  By such a cap cleaning operation, the ink attached to the cap 50 in the fill cap state can be washed away by immersing the cap 50 in the cleaning liquid. In addition, by sucking and discharging the cleaning liquid from the suction hole 56a1 by driving the pump 42, the ink attached to the suction hole 56a1 can be washed away.

  Thereby, it is possible to prevent the ink from adhering to the peripheral wall 57 and the suction hole 56a1 of the cap 50a. Even when there is ink fixed to the peripheral wall 57 or the suction hole 56a1 of the cap 50a, it can be melted and washed away with the cleaning liquid.

  Further, the suction and discharge of the cleaning liquid from the suction hole 56a1 stirs the cleaning liquid in the cleaning liquid tank 47 and causes the cleaning liquid to move, so that the ink fixed to the cap 50a can be better removed.

  The cap cleaning operation described above is not limited to the timing immediately after the fill cap state is released when the inkjet printing apparatus 1 is turned on, but may be performed at other timings. For example, it may be performed during a printing operation.

  As described above, since the inkjet printing apparatus 1 includes a plurality of caps 50 that can cap the inkjet head 31 around the cap base 52, while the inkjet head 31 is capped with one cap 50 in the standby state, Another cap 50 can be immersed in the cleaning liquid tank 47. By immersing in the cleaning liquid, even if the ink is fixed to the immersed cap 50, it can be easily removed.

In addition, when the cap time during which the previous capping is continued is longer than a predetermined time when shifting to the standby state, the control unit 5 rotates the cap base 52 by the cap rotation driving unit 46 to perform the previous time. The cap 50 that has capped the inkjet head 31 is dipped in the cleaning liquid in the cleaning liquid tank 47, and the inkjet head 31 is capped using another cap 50. This makes it easier to remove ink remaining in the cap 50 at the next cleaning.

Further, as a cleaning operation, the control unit 5 drives the pump 42 with the cap 50a immersed in the cleaning liquid to suck the cleaning liquid from the suction hole 56a1 into the suction pipe 53, and then drives the pump 42 reversely to the suction time. Then, the cleaning liquid sucked into the suction pipe 53 is controlled to be discharged from the suction hole 56a1. Accordingly, the cap 50a can be cleaned by immersing the cap 50a in the cleaning liquid, and the removal of the ink fixed to the suction hole 56a1 can be promoted by sucking and discharging the cleaning liquid from the suction hole 56a1. Therefore, according to the inkjet printing apparatus 1, insufficient cleaning of the cap 50 can be reduced.

This cleaning operation is not essential. The present invention can be applied even to an apparatus in which the user manually cleans the cap 50.

In step S6, the determination is made based on whether or not the cap time is longer than the predetermined time. However, the time during which the cap 50 is immersed in the cleaning liquid tank 47 and the number of cap cleaning processes may be included. These may be used alone.

Further, before the processing of step S7 or step S8 described above, the cap rotating motor 45 may be driven by the control unit 5 to rotate the cap base 52 by 360 degrees × N (N is an integer of 1 or more). Thereby, caps other than the cap immersed in the cleaning liquid tank 47 in step S7 and step S8 can be rinsed with the cleaning liquid one or more times, and the ink in the cap can be more easily dropped. it can. In addition, it is possible to clean dirt that has adhered to the inside of the cap or the outside of the cap due to mist generated during the printing operation.

  The present invention is not limited to the above-described embodiments as they are, and can be embodied by modifying the constituent elements without departing from the scope of the invention in the implementation stage. Moreover, various inventions can be formed by appropriately combining a plurality of components disclosed in the embodiment. For example, some components may be deleted from all the components shown in the embodiment. Furthermore, constituent elements over different embodiments may be appropriately combined.

For example, when a cleaning liquid tank raising / lowering motor that raises and lowers the cleaning liquid tank 47 is installed and the cap 50 is immersed in the cleaning liquid tank 47 in a standby state or when the cleaning liquid tank 47 is separated from the inkjet head 31 or the capping unit 41, The controller 5 may control the positional relationship among the cleaning liquid tank, the cap unit, and the inkjet head using a cleaning liquid tank lifting motor. Further, the control unit 5 may control the relative positional relationship between the cleaning liquid tank, the cap unit, and the inkjet head by cooperating the head lifting motor 25, the cap lifting motor 45, and the cleaning liquid tank lifting motor.

DESCRIPTION OF SYMBOLS 1 Inkjet printing apparatus 2 Shuttle base unit 3 Flat bed unit 4 Shuttle unit 5 Control part 6 Timer 26 Head unit 27 Cap mechanism part 28 Wipe part 41 Cap unit 42 Pump 43 Atmospheric release valve 45 Cap raising / lowering motor 46 Cap rotation drive part 47 Cleaning liquid Tank 50a, 50b Cap 51a, 51b Open end 52 Cap base 53 Suction tube 54 Air release tube 56 Ink receiving surface 57 Peripheral wall 56a1, 56b1 Suction hole 56a2, 56b2 Air release hole 59 Cap rotation motor

Claims (2)

An inkjet head having a nozzle for ejecting ink;
Two or more caps that contact the inkjet head and cover the nozzle;
A cap base that holds the two or more caps on an outer peripheral surface and is rotatable about an axis parallel to the arrangement direction of the nozzles;
A cleaning liquid tank for storing the cleaning liquid;
A drive unit for rotating the cap base;
In a standby state in which the driving unit is driven and the nozzle surface of the inkjet head is sealed with one of the two or more caps, at least one of the other caps is immersed in the cleaning liquid in the cleaning liquid tank. A control unit for controlling the positional relationship between the inkjet head, the cap, and the cleaning liquid tank so as to be in a state;
An ink jet printing apparatus comprising: When the control unit determines that the cap time during which the inkjet head is covered by the cap has continued longer than a predetermined time when shifting to the standby state, the control unit places the cap in the cleaning liquid tank. The inkjet printing apparatus according to claim 1, wherein the driving unit is controlled so as to be a cap to be immersed.