Printing device and nozzle moisturizing method

Abstract

To retain moisture of a nozzle while suppressing air bubble from entering a nozzle.SOLUTION: Moisture of nozzles 311 of discharge heads 31 can be retained with foamy cleaning liquid Lb in a maintenance unit 5 that contacts a head unit 3 for capping. In particular, in executing the capping, the foamy cleaning liquid Lb is ejected into the maintenance unit 5 so that the foamy cleaning liquid Lb in the maintenance unit 5 is separated from flat surfaces 310 of openings of the nozzles, and then the capping is executed. This can suppress air bubble included in the foamy cleaning liquid Lb from entering the nozzles 311.SELECTED DRAWING: Figure 14

Description

[Technical Field]

[0001] The present invention relates to a technique for keeping the nozzles moist by capping an ejection head that ejects ink from nozzles that open on an ink ejection surface with a cap unit. [Background technology]

[0002] Patent Document 1 describes a technique for cleaning the ejection port surface of a print head that ejects ink from nozzles that open on the ejection port surface. Specifically, a capping member is pressed against the ejection port surface, and the capping member is filled with a foamed cleaning liquid. This causes the foamed cleaning liquid to adhere to the ejection port surface and dissolve ink that has solidified on the ejection port surface. Patent Document 2 also describes a technique for moisturizing the nozzles using a foamed liquid. Specifically, the nozzles are moisturized by spraying a foamed liquid onto a liquid ejection unit that ejects ink from the nozzles, and then covering the liquid ejection unit with a moisture retention cap so that the foamed liquid is contained inside the moisture retention cap. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 11-198396 [Patent Document 2] Japanese Patent Application Laid-Open No. 2016-155252 Summary of the Invention [Problem to be solved by the invention]

[0004] In the above-mentioned Patent Document 1, the inside of the capping member that contacts the ejection port surface is filled with foamed cleaning liquid, which can cause air bubbles to enter the nozzles and interfere with the ejection of ink from the nozzles. In Patent Document 2, liquid containing air bubbles is ejected toward a position corresponding to the inside of the cap that contacts the liquid ejection unit, in other words, near the nozzles. Therefore, there is a risk that air bubbles will enter the nozzles and interfere with the ejection of ink from the nozzles.

[0005] The present invention has been made in consideration of the above-mentioned problems, and has an object to make it possible to moisturize the nozzle while suppressing the intrusion of air bubbles into the nozzle. [Means for solving the problem]

[0006] The printing device of the present invention comprises a head unit having an ejection head that ejects ink from nozzles that open on the ink ejection surface and a head holding member that holds the ejection head; a cap unit that performs capping by facing the nozzles and contacting the head unit to cover the nozzles; and a cleaning liquid ejection section that ejects foamy cleaning liquid, which is cleaning liquid containing air bubbles, into the cap unit before the cap unit performs capping, and the cleaning liquid ejection section ejects the foamy cleaning liquid into the cap unit so that the foamy cleaning liquid in the cap unit that performs capping is separated from the ink ejection surface.

[0007] The nozzle moisturizing method of the present invention includes the steps of ejecting a foamy cleaning liquid, which is a cleaning liquid containing air bubbles, into a cap unit, and performing capping by bringing the cap unit into contact with the head unit while facing the nozzle of a head unit having an ejection head that ejects ink from a nozzle that opens on the ink ejection surface and a head holding member that holds the ejection head, and the foamy cleaning liquid is ejected into the cap unit so that the foamy cleaning liquid in the cap unit that performs capping is separated from the ink ejection surface.

[0008] In the present invention (printing device and nozzle moisturizing method) configured in this manner, the nozzles of the ejection head of the head unit can be moistened by the foamed cleaning liquid in the cap unit that comes into contact with the head unit during capping. In particular, capping is performed after the foamed cleaning liquid is ejected into the cap unit so that the foamed cleaning liquid in the cap unit is separated from the ink ejection surface during capping. Therefore, compared to the above-mentioned technology that fills the inside of the capping member that comes into contact with the ejection port surface with foamed cleaning liquid or the above-mentioned technology that directly sprays foamed cleaning liquid onto the liquid ejection unit (near the nozzles), it is possible to prevent air bubbles from entering the nozzles. In this way, it is possible to moisturize the nozzles while preventing air bubbles from entering the nozzles.

[0009] The cap unit may also be configured to include a large cap having a large opening corresponding to the head unit and a small cap having a small opening smaller than the large opening and corresponding to the ink ejection surface. The small cap is positioned inside the large opening, the large cap has a large opening periphery that defines the large opening, and the small cap has a small opening periphery that defines the small opening. During capping, the large opening faces the head unit, the large opening periphery contacts the head unit, and the small opening faces the ink ejection surface. The printing device may be configured so that the cleaning liquid ejection unit ejects foamy cleaning liquid inside the large opening. In this configuration, the foamy cleaning liquid inside the large cap that contacts the head unit during capping can moisturize the nozzles of the ejection head of the head unit. Furthermore, by ejecting foamy cleaning liquid onto the cap unit as described above and then performing capping, it is possible to moisturize the nozzles while preventing air bubbles from entering the nozzles.

[0010] The large opening of the large cap is surrounded by the small opening of the small cap. By discharging the foamy cleaning liquid into either or both of the large opening and the small opening, the above-mentioned effect can be achieved.

[0011] In other words, the printing device may be configured so that the cleaning liquid ejection unit ejects foamy cleaning liquid into the small opening, and the foamy cleaning liquid in the small opening of the cap unit that performs capping is separated from the ink ejection surface. With this configuration, the nozzles of the ejection head can be moistened by the foamy cleaning liquid in the small opening that faces the ink ejection surface inside the large cap that contacts the head unit during capping. In this case, capping is performed after the foamy cleaning liquid is ejected into the small opening so that the foamy cleaning liquid in the small opening is separated from the ink ejection surface during capping. This makes it possible to moisturize the nozzles while preventing air bubbles from entering the nozzles.

[0012] The cap unit further includes a drive unit that drives the cap unit in a drive direction relative to the cleaning liquid discharge unit, and in the cap unit, a first cap row and a second cap row, each having small caps arranged in the drive direction, are arranged at different positions in a width direction perpendicular to the drive direction, The cleaning liquid ejection unit has a first ejection port provided corresponding to the first cap row and a second ejection port provided corresponding to the second cap row, and the first ejection port ejects foamy cleaning liquid into small openings of small caps in the first cap row that move in the drive direction as the drive unit is driven, and the second ejection port ejects foamy cleaning liquid into small openings of small caps in the second cap row that move in the drive direction as the drive unit is driven, and the first leading cap in the drive direction among the small caps arranged in the drive direction in the first cap row and the second leading cap in the drive direction among the small caps arranged in the drive direction in the second cap row are provided at different positions in the drive direction, and the printing device may be operated so that the timing at which the first ejection port starts ejecting foamy cleaning liquid onto the first leading cap and the timing at which the second ejection port starts ejecting foamy cleaning liquid onto the second leading cap differ depending on the difference in the positions of the first leading cap and the second leading cap in the drive direction.

[0013] In this configuration, while the cap unit is moved relative to the cleaning liquid discharger in the drive direction, foamed cleaning liquid is discharged from the cleaning liquid discharger into the small openings of the small caps. In this case, the first cap row and the second cap row are arranged at different positions in the width direction in the cap unit, while the cleaning liquid discharger has a first discharge port corresponding to the first cap row and a second discharge port corresponding to the second cap row. The first discharge port discharges foamed cleaning liquid to the small caps of the first cap row that move relatively in the drive direction, and the second discharge port discharges foamed cleaning liquid to the small caps of the second cap row that move relatively in the drive direction. However, in the drive direction, the small cap (first leading cap) located at the head of the first cap row and the small cap (second leading cap) located at the head of the second cap row are located at different positions in the drive direction. To accommodate this difference in the positions of the first and second leading caps, the timing at which the first outlet starts discharging foamed cleaning liquid to the first leading cap and the timing at which the second outlet starts discharging foamed cleaning liquid to the second leading cap are different, which allows the foamed cleaning liquid to be accurately discharged to each of the small caps in the first cap row and the second cap row.

[0014] The printing device may further include a drive unit that drives the cap unit relative to the cleaning liquid discharge unit in the drive direction. The cleaning liquid discharge unit has a discharge port that discharges foamy cleaning liquid toward a predetermined target area. The drive unit drives the discharge port to discharge foamy cleaning liquid while the inside of the small opening passes through the target area, and the drive unit does not drive the discharge port to discharge foamy cleaning liquid while the drive unit drives the small opening periphery. This configuration allows foamy cleaning liquid to be discharged toward the small opening of the small cap while avoiding the small opening periphery. This prevents foamy cleaning liquid adhering to the small opening periphery from adhering to the ink discharge surface, and further prevents air bubbles contained in the foamy cleaning liquid from entering the nozzles.

[0015] The printing device may also be configured so that the ejection target range is included inside the small opening in the width direction perpendicular to the drive direction. With this configuration, foamy cleaning liquid can be ejected onto the small opening of the small cap while avoiding the periphery of the small opening. This prevents foamy cleaning liquid adhering to the periphery of the small opening from adhering to the ink ejection surface, and further prevents air bubbles contained in the foamy cleaning liquid from entering the nozzles.

[0016] However, if capping is repeated in a short period of time, new foamy cleaning liquid may be added to the small opening before the foamy cleaning liquid in the small opening disappears (before the bubbles have vanished), and the amount of foamy cleaning liquid in the small opening may increase with each capping, which may cause the foamy cleaning liquid to reach the ink ejection surface. In such a case, air bubbles may enter the nozzles and interfere with the ejection of ink from the nozzles.

[0017] Therefore, the printing device may be configured such that the cleaning liquid discharger discharges foamed cleaning liquid to a small cap external area inside the large opening of the large cap and outside the small cap, and the size of the bubbles contained in the foamed cleaning liquid discharged into the small opening is larger than the size of the bubbles contained in the foamed cleaning liquid discharged into the small cap external area. With this configuration, foamed cleaning liquid containing relatively coarse bubbles is discharged into the small opening. Therefore, the foamed cleaning liquid in the small opening disappears relatively quickly, preventing the foamed cleaning liquid from reaching the ink discharge surface with repeated capping. Furthermore, foamed cleaning liquid containing relatively fine bubbles is discharged into the small cap external area inside the large opening of the large cap and outside the small cap. Therefore, the foamed cleaning liquid discharged into the small cap external area inside the large opening remains for a long time, contributing to moisturizing the nozzles. In this way, the nozzles can be kept moist for a long time while accurately preventing air bubbles from entering the nozzles.

[0018] The printing device may also be configured so that the cleaning liquid discharge unit discharges foamed cleaning liquid into an area inside the large opening of the large cap and outside the small cap. In this way, the nozzles are moistened by foamed cleaning liquid separated from the nozzles, so that the nozzles can be thoroughly moistened while more reliably preventing air bubbles from entering the nozzles.

[0019] In this case, the printing device may be configured so that the periphery of the small opening is separated from the ink ejection surface when capping is performed. In this configuration, moisture supplied by the foamy cleaning liquid ejected onto the outer area of ​​the small cap when capping is performed can enter the small opening through the gap between the periphery of the small opening and the ink ejection surface, contributing to keeping the nozzle moist.

[0020] The printing device may also be configured such that the cap unit is movable between a facing position and a retracted position, facing the head unit when positioned at the facing position, and not facing the head unit when positioned at the retracted position, the cleaning liquid ejection unit is provided between the retracted position and the facing position, the cap unit performs capping at the facing position, and is located at the retracted position while the ejection head ejects ink onto the print medium to print an image on the print medium, and the cleaning liquid ejection unit ejects foamy cleaning liquid onto the cap unit as it moves from the retracted position to the facing position. With this configuration, the period during which the cap unit moves from the retracted position to the facing position can be effectively used to eject foamy cleaning liquid onto the cap unit for capping.

[0021] The printing device may also be configured to further include a rinse liquid discharge unit that discharges rinse liquid, which is a bubble-free liquid, into the cap unit and a liquid discharge unit that discharges rinse liquid from the cap unit, and to perform a bubble removal process in which the rinse liquid discharge unit discharges the rinse liquid into the cap unit and then the liquid discharge unit discharges the rinse liquid from the cap unit before discharging foamy cleaning liquid into the cap unit. This configuration can effectively prevent the above-mentioned problems caused by repeated capping in a short period of time.

[0022] Various rinse liquids are conceivable. For example, the rinse liquid may be a cleaning liquid that does not contain bubbles, or may be water.

[0023] The printing device may also be configured such that the cap unit is movable between a facing position and a retracted position, facing the head unit when positioned at the facing position, and not facing the head unit when positioned at the retracted position, the rinse liquid ejection unit is provided between the retracted position and the facing position, the cap unit performs capping at the facing position, and is located at the retracted position while the ejection head ejects ink onto the printing medium to print an image on the printing medium, and the rinse liquid ejection unit ejects rinse liquid onto the cap unit as it moves from the facing position to the retracted position. With this configuration, the cap unit retracts to the retracted position when the ejection head starts printing, and the period during which the cap unit moves from the facing position to the retracted position can be effectively used to eject rinse liquid onto the cap unit.

[0024] The printing device may also be configured such that the cleaning liquid discharger is provided between the retracted position and the facing position, and the cleaning liquid discharger discharges foam cleaning liquid onto the cap unit as it moves from the retracted position to the facing position. With this configuration, the period during which the cap unit moves from the retracted position to the facing position can be effectively used to discharge foam cleaning liquid onto the cap unit for capping. [Effects of the Invention]

[0025] As described above, according to the present invention, it is possible to keep the nozzle moist while suppressing the intrusion of air bubbles into the nozzle. [Brief explanation of the drawings]

[0026] [Figure 1] 1 is a front view schematically illustrating an example of a printing apparatus according to the present invention. [Figure 2] FIG. 2 is a block diagram showing the electrical configuration of the printing apparatus shown in FIG. [Figure 3]FIG. 2 is a bottom view schematically showing the configuration of the head unit. [Figure 4] FIG. 2 is a perspective view schematically showing the configuration of a maintenance unit. [Figure 5] FIG. 2 is a diagram schematically illustrating the configuration of a first example of a cleaning liquid supply unit. [Figure 6] 6 is a diagram showing the operation of the cleaning liquid supply unit in FIG. 5 in the form of a table. [Figure 7A] FIG. 2 is a diagram schematically showing a first example of a specific configuration of a concentrate discharge unit. [Figure 7B] FIG. 10 is a diagram schematically showing a second example of a specific configuration of the concentrate discharge unit. [Figure 8A] FIG. 3 is a diagram schematically showing a first example of a specific configuration of an air discharge portion. [Figure 8B] FIG. 10 is a diagram schematically showing a second example of a specific configuration of the air discharge portion. [Figure 9] 10 is a flowchart showing an example of maintenance performed on the ejection head. [Figure 10A] FIG. 10 is a diagram schematically illustrating an example of the operation executed according to the flowchart of FIG. [Figure 10B] FIG. 10 is a diagram schematically illustrating an example of the operation executed according to the flowchart of FIG. [Figure 11A] 10 is a diagram schematically showing an example of a manner in which a cleaning liquid is ejected in a rinse mode executed in the maintenance of FIG. 9. FIG. [Figure 11B] 10 is a diagram schematically showing an example of a manner in which a cleaning liquid is ejected in a rinse mode executed in the maintenance of FIG. 9. FIG. [Figure 11C] 10 is a diagram schematically showing an example of a manner in which a cleaning liquid is ejected in a rinse mode executed in the maintenance of FIG. 9. FIG. [Figure 12] 10 is a diagram schematically showing the configuration and operation of a drainage mechanism for discharging the cleaning liquid during the maintenance shown in FIG. 9. [Figure 13A] 10 is a diagram schematically showing an example of a manner in which foamy cleaning liquid is discharged in a bubble mode executed in the maintenance of FIG. 9. FIG. [Figure 13B] 10 is a diagram schematically showing an example of a manner in which foamy cleaning liquid is discharged in a bubble mode executed in the maintenance of FIG. 9. FIG. [Figure 13C]10 is a diagram schematically showing an example of a manner in which foamy cleaning liquid is discharged in a bubble mode executed in the maintenance of FIG. 9. FIG. [Figure 13D] 10 is a diagram schematically showing an example of a manner in which foamy cleaning liquid is discharged in a bubble mode executed in the maintenance of FIG. 9. FIG. [Figure 13E] 10 is a diagram schematically showing an example of a manner in which foamy cleaning liquid is discharged in a bubble mode executed in the maintenance of FIG. 9. FIG. [Figure 14] FIG. 10 is a diagram schematically illustrating capping performed during the maintenance of FIG. 9 . [Figure 15] FIG. 10 is a diagram schematically illustrating the configuration of a second example of a cleaning liquid supply unit. [Figure 16] FIG. 10 is a diagram schematically illustrating the configuration of a third example of a cleaning liquid supply unit. [Figure 17] 6 is a diagram showing, in table form, the operation of discharging two types of foamy cleaning liquid by the cleaning liquid supply unit of FIG. 5. DETAILED DESCRIPTION OF THE INVENTION

[0027] FIG. 1 is a front view showing a schematic diagram of an example of a printing apparatus according to the present invention, and FIG. 2 is a block diagram showing the electrical configuration of the printing apparatus shown in FIG. 1. In FIG. 1 and the following figures, the horizontal X direction, the horizontal Y direction perpendicular to the X direction, and the vertical Z direction are indicated as appropriate. The printing apparatus 1 prints an image on the web W by ejecting ink onto the web W using an inkjet method while transporting the long, strip-shaped web W in a roll-to-roll manner. The web W is made of paper or film, and is flexible. The printing apparatus 1 is equipped with a control unit 10 that provides overall control of the entire apparatus, and the control required for printing and maintenance is performed by the control unit 10.

[0028] The control unit 10 is a computer having a calculation unit 11, a storage unit 12, and a communication unit 13. The calculation unit 11 is configured with a processor such as a CPU (Central Processing Unit) and executes calculations necessary for printing and maintenance. The storage unit 12 is a storage device such as an HDD (Hard Disk Drive) or SSD (Solid State Drive) and stores data necessary for printing and maintenance. The communication unit 13 executes communication with external devices such as external computers.

[0029] The printing device 1 also includes a display 14 configured, for example, by an LCD monitor, and the control unit 10 notifies the worker of the information by displaying the information on the display 14. The display 14 is configured as a touch panel and has a function of accepting input operations by the worker. Information input to the display 14 by the worker is transmitted to the control unit 10 and used for control by the control unit 10. The input function may also be configured by input devices such as a keyboard or mouse provided separately from the display 14.

[0030] The printing apparatus 1 includes a transport unit 2 that transports the web W. The transport unit 2 has a feed roller 21 and a take-up roller 22, and transports the web W roll-to-roll by winding the web W unwound by the feed roller 21 onto the take-up roller 22. The transport unit 2 includes a take-up unit 23 between the feed roller 21 and the take-up roller 22 that takes in the web W unwound from the feed roller 21. The take-up unit 23 has two drive rollers 231, two nip rollers 232, and an edge position adjustment unit 234 provided between the two drive rollers 231. Each drive roller 231 rotates by the driving force of a motor while winding the web W around it, thereby driving the web W. Two nip rollers 232 are provided corresponding to the two drive rollers 231, respectively, and each nip roller 232 sandwiches the web W between itself and the corresponding drive roller 231. The edge position adjusting unit 234 adjusts the position of the edge of the web W in the X direction, which is the width direction of the web W.

[0031] The transport unit 2 also has a plurality of support rollers 24 that support the web W between the take-in unit 23 and the winding roller 22. These support rollers 24 transport the web W in the Y direction while supporting the web W, onto which ink is ejected by an inkjet system, from below. In particular, the plurality of support rollers 24 are arranged at an incline so that the support rollers 24 on the downstream side in the transport direction (Y direction) of the web W are positioned higher. Therefore, the web W transported by these support rollers 24 is transported at an incline so as to rise as it approaches the Y direction.

[0032] The transport unit 2 further includes a plurality of support rollers 25 that support the web W between the support roller 24 and the winding roller 22, and a drying unit 26 disposed between the support rollers 25 and the winding roller 22. The drying unit 26 includes a heat drum 261 and a support roller 262 that supports the web W moving from the heat drum 261 to the winding roller 22. The heat drum 261 is driven to rotate in accordance with the transport of the web W, and dries the web W by heating the web W with a built-in heater. The transport unit 2 also includes a plurality of support rollers 27 that support the web W moving from the drying unit 26 to the winding roller 22. The transport unit 2 further includes a drive roller 281 and a nip roller 282 disposed between the support rollers 27 and the winding roller 22. The drive roller 281 rotates by the driving force of a motor while the web W is wound around it, thereby driving the web W. The nip roller 282 sandwiches the web W between the drive roller 281 and the nip roller 282.

[0033] The printing device 1 has multiple (six) head units 3 (FIG. 3) that face from above the web W, which is supported by multiple support rollers 24. FIG. 3 is a bottom view schematically illustrating the configuration of the head units. Each head unit 3 has multiple (five) ejection heads 31. The multiple ejection heads 31 are arranged at different positions in the X direction and are arranged in a staggered pattern in two rows in the X direction. In other words, a head column C31 consisting of three ejection heads 31 arranged parallel to the X direction and a head column C31 consisting of two ejection heads 31 arranged parallel to the X direction are provided in the Y direction. The bottom surface of each ejection head 31 is a nozzle opening plane 310 that faces the web W, and the nozzle opening plane 310 has a rectangular shape in bottom view. Multiple nozzles 311 open in the nozzle opening plane 310. The multiple nozzles 311 are arranged in a staggered pattern in the X direction and face the web W from above, and each nozzle 311 ejects ink onto the web W using an inkjet method. The head unit 3 has a head holding member 32 that holds each ejection head 31. The bottom surface of the head holding member 32 is a web-facing plane 320 that faces the web W, and the web-facing plane 320 has a rectangular shape when viewed from the bottom. A plurality of head insertion holes 321 are formed in the web-facing plane 320, each corresponding to one of the ejection heads 31. The plurality of ejection heads 31 are fixed to the head holding member 32 while inserted into the corresponding head insertion holes 321. The head holding member 32 can be made of a non-elastic material such as metal or resin.

[0034] 1, the posture of each of the multiple head units 3 is set according to the inclination of the web W supported by the multiple support rollers 24. In other words, the multiple head units 3 are arranged so that the more upstream the head unit 3 in the transport direction of the web W, the greater the inclination with respect to the Z direction. However, the head unit 3 at the most downstream side in the transport direction (Y direction) of the web W is arranged horizontally and is not inclined with respect to the Z direction, and the head units 3 other than the most downstream head unit 3 are inclined so as to become higher in the transport direction of the web W. The inclination of the head unit 3 can be evaluated by the angle that the nozzle opening plane 310 of the ejection head 31 in which the nozzles 311 are formed makes with respect to the Z direction.

[0035] Each of the multiple head units 3 ejects ink of a different color, including yellow, magenta, cyan, and black, from the nozzles 311 in response to a command from the control unit 10. This makes it possible to print a color image on the web W. However, the number of head units 3 and the ink colors are not limited to this example.

[0036] The printing device 1 also includes a plurality of lifting and lowering drive units 4, each provided to correspond to a respective one of the plurality of head units 3. Each lifting and lowering drive unit 4 raises or lowers the corresponding head unit 3 in response to a command from the control unit 10, thereby enabling the head unit 3 to be positioned at one of a plurality of positions at different heights. In FIG. 1, each head unit 3 is positioned at a printing height h0, which is closest to the web W. Such lifting and lowering drive unit 4 can be realized by a well-known specific configuration, and can be configured to raise or lower the head unit 3, for example, by driving a ball screw or an eccentric cam or the like with a motor.

[0037] The printing device 1 also includes a maintenance unit 5 (FIG. 4) that performs maintenance on the head unit 3 and a horizontal drive unit 61 that drives the maintenance unit 5 in the horizontal direction (X direction). The maintenance unit 5 and horizontal drive unit 61 are provided for each of the multiple head units 3. Driven in the X direction by the horizontal drive unit 61, the maintenance unit 5 moves between a facing position Pa facing the head unit 3 and a retracted position Pb retracted in the X direction from the head unit 3, as described below with reference to FIGS. 10A and 10B. The horizontal drive unit 61 can be configured, for example, with a rail extending in the X direction that supports the maintenance unit 5 and a linear motor that drives the maintenance unit 5 in the X direction. Instead of a linear motor, a mechanism that uses a motor to rotate a pulley around which a belt attached to the maintenance unit 5 is wound, or a ball screw that linearly moves the maintenance unit 5, may be used. Next, the maintenance unit 5 will be described in detail.

[0038] FIG. 4 is a perspective view that schematically illustrates the configuration of the maintenance unit. In FIG. 4 and the following figures, one side X1 and the other side X2 in the X direction are shown as appropriate. Here, one side X1 and the other side X2 face opposite each other. As described above, a maintenance unit 5 is provided for each of the multiple head units 3, and each maintenance unit 5 faces the corresponding head unit 3 from below. In this case, the maintenance unit 5 is also tilted in accordance with the tilt of the head unit 3. However, because the tilt of the maintenance unit 5 is slight, the tilt of the maintenance unit 5 is not reflected in FIG. 4 and the following figures. Furthermore, because the multiple maintenance units 5 provided corresponding to the multiple head units 3 have a common configuration, the following description will focus on one maintenance unit 5.

[0039] The maintenance unit 5 has a large cap 51 having a rectangular parallelepiped outer shape extending in the X direction, and a horizontal drive unit 61 (FIG. 2) supports the large cap 51 and drives the large cap 51 in the X direction. The large cap 51 has a large opening 52 that is rectangular in shape and extends in the X direction in a plan view. The large opening 52 has long sides parallel to the X direction and short sides parallel to the Y direction and shorter than the long sides. The large opening 52 is a hole that opens upward and has a bottom 521. The large cap 51 also has a peripheral edge 53 that surrounds the large opening 52 in a plan view. In other words, the peripheral edge 53 defines the large opening 52. The peripheral edge 53 has a side 531 located at one end on the X1 side and a side 532 located at the other end on the X2 side, and the side 531 and the side 532 each extend parallel to the Y direction. The peripheral edge portion 53 has side portions 533 and 534 arranged at both ends in the Y direction, and the side portions 533 and 534 each extend parallel to the X direction.

[0040] Furthermore, the maintenance unit 5 has a plurality (five) of small caps 54 corresponding to the plurality (five) of ejection heads 31 of the head unit 3. The plurality of small caps 54 are arranged inside the large opening 52 in a plan view, and are arranged in two rows in a staggered pattern in the X direction on the bottom 521 of the large opening 52. Each small cap 54 has a rectangular parallelepiped shape extending in the X direction, and in a plan view, has long sides parallel to the X direction and short sides parallel to the Y direction and shorter than the long sides. Each small cap 54 has a small opening 55 that is rectangular in a plan view, and has long sides parallel to the X direction and short sides parallel to the Y direction and shorter than the long sides. The small opening 55 is a hole that opens upward and has a bottom 551. Furthermore, the small cap 54 has a peripheral edge 56 that surrounds the small opening 55 in a plan view. In other words, the peripheral edge 56 defines the small opening 55. Peripheral edge 56 has a side 561 located at the end of one side X1 and a side 562 located at the end of the other side X2, with side 561 and side 562 extending parallel to the Y direction. Peripheral edge 56 also has side portions 563 and 564 located at both ends in the Y direction, with side portions 563 and 564 extending parallel to the X direction.

[0041] In the X direction, the small caps 54 are shorter than the large openings 52 of the large caps 51, and the small openings 55 of the small caps 54 are shorter than the large openings 52 of the large caps 51. Similarly, in the Y direction, the small caps 54 are shorter than the large openings 52 of the large caps 51, and the small openings 55 of the small caps 54 are shorter than the large openings 52 of the large caps 51. In other words, in a plan view, the areas of the small caps 54 and the small openings 55 are each smaller than the area of ​​the large openings 52 of the large caps 51. In particular, the large openings 52 of the large caps 51 are configured to accommodate the plurality of small caps 54 arranged in a two-row staggered pattern as described above.

[0042] In this way, the maintenance unit 5 has a plurality of small caps 54 corresponding to the plurality of ejection heads 31 of the head unit 3, and each small cap 54 faces the corresponding ejection head 31 from below. The plurality of small caps 54 are arranged in two rows in a staggered pattern in the X direction, in other words, a cap column C54 consisting of three small caps 54 arranged parallel to the X direction, and a cap column C54 consisting of two small caps 54 arranged parallel to the X direction are provided in the Y direction.

[0043] The maintenance unit 5 also has a wiper 591 made of an elastic member that is elastically deformable, such as rubber or silicone. The wiper 591 is a flat blade that extends parallel to the Y direction and stands upright from a side portion 532 of the large cap 51. The wiper 591 is provided corresponding to each of the multiple (two) cap rows C54, and each wiper 591 is disposed on the other side X2 in the X direction of the corresponding cap row C54. The wiper 591 can scrape off ink from the nozzle opening plane 310 of the ejection head 31 by moving to one side X1.

[0044] Furthermore, the maintenance unit 5 has a tank mounting portion 592 provided for each of the multiple wipers 591. This tank mounting portion 592 is a hole that opens upward and is formed in the side portion 532 of the large cap 51. It is located below the corresponding wiper 591, and a waste liquid container 593 is inserted into each tank mounting portion 592. In this way, a waste liquid container 593 is provided below each of the multiple wipers 591. Each waste liquid container 593 is a box-shaped tank that opens upward and faces the corresponding wiper 591 from below. The waste liquid container 593 stores ink that has been scraped off by the wiper 591 and dropped from the wiper 591. Note that the waste liquid container 593 does not have to be a box, and may be a pan that collects ink.

[0045] The printing device 1 also includes a cleaning liquid supply unit 8 that supplies liquid to the maintenance unit 5. In particular, the cleaning liquid supply unit 8 has a mechanism that selectively supplies one of two types of liquid to the small cap 54. Next, the configuration and operation of the cleaning liquid supply unit 8 will be described.

[0046] Fig. 5 is a diagram schematically illustrating the configuration of a first example of a cleaning liquid supply unit, and Fig. 6 is a diagram in tabular form illustrating the operation of the cleaning liquid supply unit of Fig. 5. This cleaning liquid supply unit 8 has an undiluted liquid discharge unit 81 that discharges cleaning liquid Lo (undiluted liquid), an air discharge unit 82 that discharges air A, a pipe 841 that guides the cleaning liquid Lo discharged from the undiluted liquid discharge unit 81 to a mixing region 83, a pipe 842 that guides the air A discharged from the air discharge unit 82 to the mixing region 83, and a cleaning liquid nozzle 85 that communicates with the mixing region 83. The cleaning liquid nozzle 85 has an opening 851 that opens downward and discharges liquid from the opening 851. The cleaning liquid Lo discharged from the undiluted liquid discharge unit 81 is a liquid that contains, for example, a surfactant and does not contain air bubbles.

[0047] As shown in the "bubble mode" in FIG. 6, when the undiluted liquid discharger 81 discharges the cleaning liquid Lo while the air discharger 82 discharges air, the cleaning liquid Lo discharged from the undiluted liquid discharger 81 and the air A discharged from the air discharger 82 are mixed in the mixing region 83. As a result, the foamy air A is mixed with the cleaning liquid Lo, and a foamy cleaning liquid Lb containing bubbles (= cleaning liquid Lo + air A) is generated. This foamy cleaning liquid Lb is then discharged from the opening 851 of the cleaning liquid nozzle 85. Also, as shown in the "rinse mode" in FIG. 6, when the undiluted liquid discharger 81 discharges the cleaning liquid Lo while the air discharger 82 stops discharging air, the cleaning liquid Lo discharged from the undiluted liquid discharger 81 flows into the cleaning liquid nozzle 85 via the mixing region 83 and is discharged from the cleaning liquid nozzle 85. In other words, the cleaning liquid supply unit 8 executes the bubble mode to eject foamy cleaning liquid Lb containing bubbles from the cleaning liquid nozzle 85, and executes the rinse mode to eject cleaning liquid Lo not containing bubbles from the cleaning liquid nozzle 85.

[0048] Various specific configurations of the above-described stock solution discharge unit 81 are conceivable. Here, two representative examples (FIGS. 7A and 7B) will be described. FIG. 7A is a diagram schematically illustrating a first example of a specific configuration of the stock solution discharge unit. The stock solution discharge unit 81 in FIG. 7A includes a syringe 811, an actuator 812a that drives the syringe 811, and a cleaning solution tank 813 that stores cleaning solution Lo. The syringe 811 includes a barrel 811b and a plunger 811p fitted in the barrel 811b. The plunger 811p is moved relative to the syringe 811 when the actuator 812a drives the plunger 811p. Note that the driving means for driving the plunger 811p is not limited to the actuator 812a and may be, for example, a motor. The barrel 811b and the cleaning solution tank 813 are connected by a pipe 814, and a check valve 815 is attached to the pipe 814. Check valve 815 allows the cleaning solution Lo to flow from the cleaning solution tank 813 to barrel 811b, but prohibits the cleaning solution Lo from flowing from barrel 811b to the cleaning solution tank 813. Barrel 811b is connected to outlet 816 of concentrate discharge part 81 by piping 817, and check valve 818 is attached to piping 817. Check valve 818 allows the cleaning solution Lo to flow from barrel 811b to outlet 816, but prohibits the cleaning solution Lo from flowing from outlet 816 to barrel 811b.

[0049] In the concentrate discharge unit 81, when the actuator 812a moves the plunger 811p in a direction to pull it out of the barrel 811b (to the left in FIG. 7A), the cleaning liquid Lo that has flowed out from the cleaning liquid tank 813 is filled into the barrel 811b. When the actuator 812a moves the plunger 811p in a direction to push it into the barrel 811b (to the right in FIG. 7A), the cleaning liquid Lo that has flowed out from the barrel 811b is discharged from the discharge port 816 into the mixing region 83. This operation of the actuator 812a is controlled by the control unit 10.

[0050] 7B is a diagram schematically illustrating a second example of the specific configuration of the concentrate discharge unit. The concentrate discharge unit 81 in FIG. 7B includes a cleaning liquid tank 813 that stores the cleaning liquid Lo, a pipe 819 that connects the concentrate discharge unit 81 to a discharge port 816, and a liquid feed pump 812p attached to the pipe 819. A gear pump, a diaphragm pump, or the like can be used as the liquid feed pump 812p. The cleaning liquid Lo is fed from the cleaning liquid tank 813 to the discharge port 816 by the liquid feed pump 812p, and is discharged from the discharge port 816 to the mixing region 83. Note that this operation of the liquid feed pump 812p is controlled by the control unit 10.

[0051] Various specific configurations of the air discharge unit described above are possible. Here, two representative examples (FIGS. 8A and 8B) will be described. FIG. 8A is a diagram schematically illustrating a first example of a specific configuration of the air discharge unit. This air discharge unit 82 includes an inlet 821 that takes in air A, an outlet 822 that discharges air A, a pipe 823 that connects the inlet 821 and the outlet 822, and a solenoid valve 824 attached to the pipe 823. Air A is supplied to the inlet 821 from an external compressor. When the solenoid valve 824 connects the inlet 821 and the outlet 822 (the state shown in FIG. 8A), the air A supplied to the inlet 821 is discharged from the outlet 822 to the mixing region 83. On the other hand, when the solenoid valve 824 blocks the inlet 821 and the outlet 822, the supply of air A from the outlet 822 to the mixing region 83 is stopped. The operation of the solenoid valve 824 is controlled by the control unit 10.

[0052] 8B is a diagram schematically illustrating a second example of the specific configuration of the air discharge unit. This air discharge unit 82 includes an inlet 821 that takes in air A, an outlet 822 that discharges air A, a pipe 823 that connects the inlet 821 and the outlet 822, and an air pump 825 attached to the pipe 823. When the air pump 825 sends air from the inlet 821 to the outlet 822, the air A sucked from the inlet 821 is discharged from the outlet 822 into the mixing region 83. When the air pump 825 stops sending air, the supply of air A from the outlet 822 to the mixing region 83 stops. Note that this operation of the air pump 825 is controlled by the control unit 10.

[0053] The maintenance unit 5 and cleaning liquid supply unit 8 perform maintenance to moisturize the nozzles 311 of the ejection head 31 while printing is stopped. In particular, the cleaning liquid supply unit 8 ejects foamy cleaning liquid Lb onto the large cap 51 and small cap 54, and then caps the head unit 3 with the large cap 51 and small cap 54, thereby moisturizing the nozzles 311. This maintenance will be described next.

[0054] Fig. 9 is a flowchart showing an example of maintenance performed on a discharge head, and Fig. 10A and Fig. 10B are diagrams schematically showing an example of the operation performed in accordance with the flowchart of Fig. 9. Before describing each step of the flowchart of Fig. 9, the underlying configuration will be described using Fig. 10A and Fig. 10B.

[0055] As described above, the maintenance unit 5 moves in the X direction by being driven by the horizontal drive unit 61. As shown in particular in FIGS. 10A and 10B, a facing position Pa and a retracted position Pb that are different from each other in the X direction are provided for the maintenance unit 5, and the maintenance unit 5 moves between the facing position Pa and the retracted position Pb. Here, the facing position Pa is a position facing the head unit 3, and the retracted position Pb is a position provided at a distance from the facing position Pa in the X direction. This retracted position Pb is provided on one side X1 of the facing position Pa.

[0056] When the maintenance unit 5 is located at the facing position Pa, the maintenance unit 5 faces the head unit 3 from below. Therefore, the large opening 52 of the large cap 51 faces all of the multiple ejection heads 31 of the head unit 3, and in a bottom view, the nozzle opening planes 310 of all of the ejection heads 31 are included inside the large opening 52. Furthermore, the multiple small caps 54 face the multiple ejection heads 31, respectively, and in a bottom view, all of the nozzles 311 that open in the nozzle opening planes 310 are included inside the small openings 55 of the small caps 54 that face the nozzle opening planes 310.

[0057] On the other hand, when the maintenance unit 5 is located at the retracted position Pb, the maintenance unit 5 retracts in the X direction from the head unit 3. In other words, in a plan view, the maintenance unit 5 is located on one side X1 of the head unit 3 in the X direction and does not overlap with the head unit 3.

[0058] The cleaning liquid supply unit 8 is provided between the facing position Pa and the retracted position Pb in the X direction, and the cleaning liquid nozzle 85 of the cleaning liquid supply unit 8 faces the range between the facing position Pa and the retracted position Pb from above. In other words, the discharge target range R into which the cleaning liquid nozzle 85 discharges the liquid (foamy cleaning liquid Lb or cleaning liquid Lo) is located between the facing position Pa and the retracted position Pb in the X direction.

[0059] Furthermore, the printing device 1 is provided with two cleaning liquid supply units 8 corresponding to the two cap rows C54 of the maintenance unit 5. These two cleaning liquid supply units 8 operate independently of each other and can selectively execute bubble mode or rinse mode. Specifically, two cleaning liquid nozzles 85 corresponding to the two cleaning liquid supply units 8 are aligned in the Y direction, and the discharge target range R of each cleaning liquid nozzle 85 overlaps with the movement path of the corresponding cap row C54 in the X direction. Each cleaning liquid nozzle 85 then discharges a liquid (foamy cleaning liquid Lb or cleaning liquid Lo) according to the mode onto the corresponding cap row C54.

[0060] Furthermore, the printing device 1 is provided with a flat cover member 63 provided at the retracted position Pb. The cover member 63 and the head unit 3 are aligned at an interval in the X direction, and the cover member 63 faces the maintenance unit 5 located at the retracted position Pb from above, thereby covering the multiple caps 52 of the maintenance unit 5. In other words, the cleaning liquid nozzle 85 of the cleaning liquid supply unit 8 ejects liquid into the ejection target range R between the head unit 3 and the cover member 63 in the X direction.

[0061] As described above, the head unit 3 moves up and down in response to a driving force from the lifting drive unit 4. That is, the head unit 3 moves up and down in the Z direction between a printing height h0 (FIG. 1), a capping height h1 (FIGS. 10A and 10B), and a moving height h2 (FIGS. 10A and 10B), which are all different from one another. Here, the printing height h0 is a position close to the web W, the moving height h2 is a position farther away from the web W than the printing height h0, and the capping height h1 is a position farther away from the web W than the printing height h0 and closer to the web W than the moving height h2.

[0062] Based on the above-described premise configuration, each step of the flowchart in Fig. 9 will be described. Each step in Fig. 9 is executed under the control of the control unit 10. Note that the maintenance in Fig. 9 is executed repeatedly, and at the start of the maintenance in Fig. 9, the maintenance unit 5 is capping the head unit 3. Therefore, the maintenance unit 5 located at the opposing position Pa faces the head unit 3 located at the capping height h1 from below, and the peripheral portion 53 of the large cap 51 of the maintenance unit 5 is in contact with the web-facing flat surface 320 of the head unit 3 (the "S101" column in Fig. 10A).

[0063] In step S101, when the control unit 10 receives a print instruction instructing execution of printing, step S102 is executed. In this step S102, the elevation drive unit 4 raises the head unit 3 from the capping height h1 to the moving height h2, separating the head unit 3 from the maintenance unit 5, thereby releasing the capping. Then, the horizontal drive unit 61 drives the maintenance unit 5 in the X direction from the facing position Pa to the retracted position Pb (step S103). In this way, during the movement from the facing position Pa to the retracted position Pb, the maintenance unit 5 passes through the discharge target range R to one side X1. In response to this, the cleaning liquid supply unit 8 executes the rinse mode, thereby discharging the cleaning liquid Lo (rinse liquid) from the cleaning liquid nozzle 85 into the discharge target range R (step S104). As a result, the cleaning liquid Lo is discharged onto the maintenance unit 5.

[0064] 11A to 11C are diagrams showing an example of the manner in which the cleaning liquid is discharged in the rinse mode executed in the maintenance of FIG. 9. In the rinse mode, as the maintenance unit 5 moves to one side X1, the discharge target ranges Ra and Rb move to the other side X2 relative to the maintenance unit 5. In contrast, in the explanation using FIGS. 11A to 11C, the five small caps 54 are numbered from first to fifth from the upstream side of the other side X2. This corresponds to the order in which the cleaning liquid Lo is discharged.

[0065] 11A to 11C show two discharge target ranges R of two cleaning liquid nozzles 85, and are given different symbols Ra and Rb to distinguish them. The discharge target range Ra corresponds to the cap row C54 made up of three small caps 54 (the first, third, and fifth small caps 54) lined up in the X direction, and the discharge target range Rb corresponds to the cap row C54 made up of two small caps 54 (the second and fourth small caps 54) lined up in the X direction. In addition, in FIGS. 11A to 11C, the white discharge target ranges Ra and Rb indicate that the cleaning liquid Lo is not discharged into those discharge target ranges Ra and Rb, and the hatched discharge target ranges Ra and Rb indicate that the cleaning liquid Lo is discharged into those discharge target ranges Ra and Rb.

[0066] 11A, in the Y direction, the discharge target range R (Ra, Rb) is included inside two imaginary lines (dashed lines parallel to the X direction) provided at both ends of the small opening 55 of the small cap 54. In other words, in the Y direction, the discharge target range R (Ra, Rb) is included inside the corresponding small opening 55 of the small cap 54. Furthermore, in the X direction, the discharge target range R (Ra, Rb) is shorter than the corresponding small opening 55 of the small cap 54.

[0067] As described above, in the rinse mode shown in FIGS. 11A to 11C , the discharge target ranges Ra and Rb move toward the other side X2 relative to the maintenance unit 5. At time Ta1, the discharge target ranges Ra and Rb are located on the one side X1 of the side 531 of the large cap 51, and the cleaning liquid Lo is not discharged toward the discharge target ranges Ra and Rb. As the discharge target ranges Ra and Rb move toward the other side X2, they pass through the side 531 of the large cap 51 and reach the large opening 52. Furthermore, when the discharge target range Ra passes through the side 561 of the first small cap 54 and reaches the small opening 55 of the first small cap 54 at time Ta2, discharge of the cleaning liquid Lo toward the discharge target range Ra begins. As a result, the cleaning liquid Lo is discharged toward the small opening 55 of the first small cap 54. Note that the cleaning liquid Lo is not discharged toward the discharge target ranges Ra and Rb between time Ta1 and time Ta2. In other words, while the ejection target ranges Ra and Rb pass through the side 531 of the large cap 51, the ejection of cleaning liquid Lo onto the ejection target ranges Ra and Rb is stopped, and while the ejection target range Ra passes through the side 561 of the first small cap 54, the ejection of cleaning liquid Lo onto the ejection target range Ra is stopped.

[0068] When the discharge target range Rb passes the side portion 561 of the second small cap 54 and reaches the small opening 55 of the second small cap 54 at time Ta3, discharge of the cleaning liquid Lo into the discharge target range Rb begins. As a result, the cleaning liquid Lo is discharged into the small opening 55 of the second small cap 54. Note that, between time Ta2 and time Ta3, the discharge of the cleaning liquid Lo into the discharge target range Ra continues, but the cleaning liquid Lo is not discharged into the discharge target range Rb. In other words, during the period when the discharge target range Rb passes the side portion 561 of the second small cap 54, the discharge of the cleaning liquid Lo into the discharge target range Rb is stopped.

[0069] At time Ta4, when the discharge target range Ra enters within a predetermined range from the side 562 of the first small cap 54 (in other words, when it approaches the side 562), discharge of the cleaning liquid Lo to the discharge target range Ra is stopped. In this way, discharge of the cleaning liquid Lo to the discharge target range Ra is stopped before the discharge target range Ra reaches the side 562 of the first small cap 54. This completes the discharge of the cleaning liquid Lo to the small opening 55 of the first small cap 54. Note that between time Ta3 and time Ta4, discharge of the cleaning liquid Lo to the discharge target ranges Ra and Rb continues.

[0070] When the discharge target range Ra passes the side 562 of the first small cap 54 and the side 561 of the third small cap 54 and reaches the small opening 55 of the third small cap 54 at time Ta5, discharge of the cleaning liquid Lo onto the discharge target range Ra begins. As a result, the cleaning liquid Lo is discharged onto the small opening 55 of the third small cap 54. Note that, between time Ta4 and time Ta5, discharge of the cleaning liquid Lo onto the discharge target range Rb continues, and the cleaning liquid Lo is not discharged onto the discharge target range Ra. In other words, during the period when the discharge target range Ra passes the side 562 of the first small cap 54 and the side 561 of the third small cap 54, discharge of the cleaning liquid Lo onto the discharge target range Ra is stopped.

[0071] At time Ta6, when the discharge target range Rb enters within a predetermined range from the side 562 of the second small cap 54 (in other words, when it approaches the side 562), discharge of the cleaning liquid Lo onto the discharge target range Rb is stopped. In this way, discharge of the cleaning liquid Lo onto the discharge target range Rb is stopped before the discharge target range Rb reaches the side 562 of the second small cap 54. This completes the discharge of the cleaning liquid Lo onto the small opening 55 of the second small cap 54. Note that between time Ta5 and time Ta6, discharge of the cleaning liquid Lo onto the discharge target ranges Ra and Rb continues.

[0072] When the discharge target range Rb passes through the side 562 of the second small cap 54 and the side 561 of the fourth small cap 54 and reaches the small opening 55 of the fourth small cap 54 at time Ta7, discharge of the cleaning liquid Lo onto the discharge target range Rb begins. As a result, the cleaning liquid Lo is discharged onto the small opening 55 of the fourth small cap 54. Note that, between time Ta6 and time Ta7, discharge of the cleaning liquid Lo onto the discharge target range Ra continues, but the cleaning liquid Lo is not discharged onto the discharge target range Rb. In other words, during the period when the discharge target range Rb passes through the side 562 of the second small cap 54 and the side 561 of the fourth small cap 54, discharge of the cleaning liquid Lo onto the discharge target range Rb is stopped.

[0073] At time Ta8, when the discharge target range Ra enters within a predetermined range from the side 562 of the third small cap 54 (in other words, when it approaches the side 562), discharge of the cleaning liquid Lo to the discharge target range Ra is stopped. In this way, discharge of the cleaning liquid Lo to the discharge target range Ra is stopped before the discharge target range Ra reaches the side 562 of the third small cap 54. This completes the discharge of the cleaning liquid Lo to the small opening 55 of the third small cap 54. Note that between time Ta7 and time Ta8, discharge of the cleaning liquid Lo to the discharge target ranges Ra and Rb continues.

[0074] When the discharge target range Ra passes the side 562 of the third small cap 54 and the side 561 of the fifth small cap 54 and reaches the small opening 55 of the fifth small cap 54 at time Ta9, discharge of the cleaning liquid Lo onto the discharge target range Ra begins. As a result, the cleaning liquid Lo is discharged onto the small opening 55 of the fifth small cap 54. Note that, between time Ta8 and time Ta9, discharge of the cleaning liquid Lo onto the discharge target range Rb continues, and the cleaning liquid Lo is not discharged onto the discharge target range Ra. In other words, during the period when the discharge target range Ra passes the side 562 of the third small cap 54 and the side 561 of the fifth small cap 54, discharge of the cleaning liquid Lo onto the discharge target range Ra is stopped.

[0075] At time Ta10, when the discharge target range Rb enters within a predetermined range from the side 562 of the fourth small cap 54 (in other words, when it approaches the side 562), discharge of the cleaning liquid Lo onto the discharge target range Rb is stopped. In this way, discharge of the cleaning liquid Lo onto the discharge target range Rb is stopped before the discharge target range Rb reaches the side 562 of the fourth small cap 54. This completes the discharge of the cleaning liquid Lo onto the small opening 55 of the fourth small cap 54. Note that between time Ta9 and time Ta10, discharge of the cleaning liquid Lo onto the discharge target ranges Ra and Rb continues.

[0076] At time Ta11, when the discharge target range Ra enters within a predetermined range from the side 562 of the fifth small cap 54 (in other words, when it approaches the side 562), discharge of the cleaning liquid Lo onto the discharge target range Ra is stopped. In this way, discharge of the cleaning liquid Lo onto the discharge target range Ra is stopped before the discharge target range Ra reaches the side 562 of the fifth small cap 54. This completes discharge of the cleaning liquid Lo onto the small opening 55 of the fifth small cap 54. Note that between time Ta10 and time Ta11, discharge of the cleaning liquid Lo onto the discharge target range Ra continues, but the cleaning liquid Lo is not discharged onto the discharge target range Rb. Then, with the discharge of the cleaning liquid Lo onto the discharge target range Ra stopped, the discharge target range Ra passes the side 562 of the small cap 54 and the side 531 of the large cap 51, and the discharge target range Rb passes the side 531 of the large cap 51.

[0077] In this way, the cleaning liquid Lo is discharged into the small openings 55 of the plurality of (five) small caps 54 of the maintenance unit 5. In other words, the cleaning liquid Lo is selectively discharged into the small openings 55, and is not discharged into portions other than the small openings 55 (the peripheral portions 53 of the small caps 54 and the large cap 51).

[0078] 9, 10A, and 10B, the explanation will be continued. In this manner, while the maintenance unit 5 is moving from the facing position Pa to the retracted position Pb, the cleaning liquid Lo is ejected into the small openings 55 of each small cap 54 (step S104). Then, when the maintenance unit 5 arrives at the retracted position Pb ("YES" in step S105), printing starts (step S106). This printing is performed by ejecting ink onto the web W from the nozzles 311 of the ejection head 31.

[0079] In parallel with this printing, the cleaning liquid Lo is discharged from the small opening 55 of the small cap 54 (step S107). FIG. 12 is a diagram schematically showing the configuration and operation of a drainage mechanism for discharging the cleaning liquid during the maintenance of FIG. 9. As shown in FIG. 12, the printing apparatus 1 is equipped with a drainage mechanism 65. The drainage mechanism 65 has a plurality of pipes 651 corresponding to the plurality of small caps 54, and each pipe 651 is connected to a corresponding small cap 54. Specifically, a drainage port 552 penetrates the bottom 551 of the small opening 55, and the pipe 651 is connected to the drainage port 552 and communicates with the small opening 55. Each pipe 651 is flexible and can deform in accordance with the movement of the corresponding small cap 54.

[0080] The drainage mechanism 65 also has a pipe 652 connected to the multiple pipes 651. One end of the pipe 652 is a branch point 652j to which the multiple pipes 651 are connected, and the other end of the pipe 652 is a drain 652d for discharging the cleaning liquid Lo. The drainage mechanism 65 also has a pump 653 attached to the pipe 652, and an electromagnetic valve 654 attached to the pipe 652 between the branch point 652j and the pump 653.

[0081] Therefore, by driving the pump 653 while opening the electromagnetic valve 654, the drainage mechanism 65 can collect the cleaning liquid Lo from the small opening 55 of each small cap 54 and discharge it from the drain 652d. On the other hand, by closing the electromagnetic valve 654 and stopping the pump 653, the drainage mechanism 65 can store the cleaning liquid Lo in the small opening 55 of the small cap 54. In particular, in step S107 of FIG. 9, the drainage mechanism 65 discharges the cleaning liquid Lo from the small opening 55 of each small cap 54.

[0082] When the control unit 10 confirms the end of printing in step S108, the horizontal drive unit 61 drives the maintenance unit 5 in the X direction from the retracted position Pb toward the opposing position Pa (step S109). In this way, while moving from the retracted position Pb to the opposing position Pa, the maintenance unit 5 passes through the discharge target range R from one side X1 to the other side X2. In response to this, the cleaning liquid supply unit 8 executes the bubble mode, thereby discharging foamy cleaning liquid Lb from the cleaning liquid nozzle 85 into the discharge target range R (step S110). As a result, the foamy cleaning liquid Lb is discharged onto the maintenance unit 5.

[0083] 13A to 13E are diagrams schematically illustrating an example of the manner in which the foamy cleaning liquid is discharged in the bubble mode executed during the maintenance of FIG. 9. In the bubble mode, as the maintenance unit 5 moves toward the other side X2, the discharge target ranges Ra and Rb move toward one side X1 relative to the maintenance unit 5. In contrast, in the description using FIGS. 13A to 13E, the five small caps 54 are numbered first through fifth from the upstream side of the one side X1. This corresponds to the order in which the foamy cleaning liquid Lb is discharged. In other words, the discharge target range Ra discharges the foamy cleaning liquid Lb to three small caps 54 (the first, third, and fifth small caps 54), and the discharge target range Rb discharges the foamy cleaning liquid Lb to two small caps 54 (the second and fourth small caps 54). The notation of the discharge target ranges Ra and Rb in FIGS. 13A to 13E is the same as that in FIGS. 11A to 11C.

[0084] As described above, in the bubble mode shown in FIGS. 13A to 13E, the discharge target areas Ra, Rb move toward one side X1 relative to the maintenance unit 5. At time Tb1, the discharge target areas Ra, Rb are located on the other side X2 of the side 532 of the large cap 51, and foamy cleaning liquid Lb is not discharged toward the discharge target areas Ra, Rb. As the discharge target areas Ra, Rb move toward the one side X1, they pass through the side 532 of the large cap 51 and reach the inside of the large opening 52 at time Tb2, at which point the discharge of foamy cleaning liquid Lb toward the discharge target areas Ra, Rb begins. As a result, foamy cleaning liquid Lb is discharged toward the large opening 52 of the large cap 51. Note that foamy cleaning liquid Lb is not discharged toward the discharge target areas Ra, Rb between time Tb1 and time Tb2. That is, while the target areas Ra and Rb pass through the side portions 532 of the large cap 51, the discharge of the foamy cleaning liquid Lb onto the target areas Ra and Rb is stopped.

[0085] At time Tb3, when the discharge target range Ra enters within a predetermined range from the side 562 of the first small cap 54 (in other words, when it approaches the side 562), discharge of the foamy cleaning liquid Lb onto the discharge target range Ra is stopped. In this way, discharge of the foamy cleaning liquid Lb onto the discharge target range Ra is stopped before the discharge target range Ra reaches the side 562 of the first small cap 54. Note that, between time Tb2 and time Tb3, discharge of the foamy cleaning liquid Lb onto the discharge target ranges Ra and Rb continues.

[0086] When the discharge target range Ra passes the side portion 562 of the first small cap 54 and reaches the small opening 55 of the first small cap 54 at time Tb4, discharge of foamy cleaning liquid Lb onto the discharge target range Ra begins. As a result, the foamy cleaning liquid Lb is discharged onto the small opening 55 of the first small cap 54. Note that, between time Tb3 and time Tb4, discharge of foamy cleaning liquid Lb onto the discharge target range Rb continues, but foamy cleaning liquid Lb is not discharged onto the discharge target range Ra. In other words, while the discharge target range Ra passes the side portion 562 of the first small cap 54, discharge of foamy cleaning liquid Lb onto the discharge target range Ra is stopped.

[0087] At time Tb5, when the discharge target range Rb enters within a predetermined range from the side 562 of the second small cap 54 (in other words, when it approaches the side 562), discharge of the foamy cleaning liquid Lb onto the discharge target range Rb is stopped. In this way, discharge of the foamy cleaning liquid Lb onto the discharge target range Rb is stopped before the discharge target range Rb reaches the side 562 of the second small cap 54. Note that between time Tb4 and time Tb5, discharge of the foamy cleaning liquid Lb onto the discharge target ranges Ra and Rb continues.

[0088] When the discharge target range Rb passes the side portion 562 of the second small cap 54 and reaches the small opening 55 of the second small cap 54 at time Tb6, discharge of foamy cleaning liquid Lb onto the discharge target range Rb begins. As a result, the foamy cleaning liquid Lb is discharged onto the small opening 55 of the second small cap 54. Note that, from time Tb5 to time Tb6, discharge of foamy cleaning liquid Lb onto the discharge target range Ra continues, but foamy cleaning liquid Lb is not discharged onto the discharge target range Rb. In other words, while the discharge target range Rb passes the side portion 562 of the second small cap 54, discharge of foamy cleaning liquid Lb onto the discharge target range Rb is stopped.

[0089] At time Tb7, when the discharge target range Ra enters within a predetermined range from the side 561 of the first small cap 54 (in other words, when it approaches the side 561), discharge of the foamy cleaning liquid Lb onto the discharge target range Ra is stopped. In this way, discharge of the foamy cleaning liquid Lb onto the discharge target range Ra is stopped before the discharge target range Ra reaches the side 561 of the first small cap 54. This completes the discharge of the foamy cleaning liquid Lb onto the small opening 55 of the first small cap 54. Note that between time Ta6 and time Ta7, discharge of the foamy cleaning liquid Lb onto the discharge target ranges Ra and Rb continues.

[0090] When the discharge target range Ra passes the side 561 of the first small cap 54 and reaches between the first and third small caps 54 at time Tb8, discharge of foamy cleaning liquid Lb onto the discharge target range Ra begins. As a result, the foamy cleaning liquid Lb is discharged onto the large opening 52. Note that, from time Ta7 to time Ta8, discharge of foamy cleaning liquid Lb onto the discharge target range Rb continues, but foamy cleaning liquid Lb is not discharged onto the discharge target range Ra. In other words, while the discharge target range Ra passes the side 561 of the first small cap 54, discharge of foamy cleaning liquid Lb onto the discharge target range Ra is stopped.

[0091] At time Tb9, when the discharge target range Ra enters within a predetermined range from the side 562 of the third small cap 54 (in other words, when it approaches the side 562), discharge of the foamy cleaning liquid Lb onto the discharge target range Ra is stopped. In this way, discharge of the foamy cleaning liquid Lb onto the discharge target range Ra is stopped before the discharge target range Ra reaches the side 562 of the third small cap 54. Note that between time Tb8 and time Tb9, discharge of the foamy cleaning liquid Lb onto the discharge target ranges Ra and Rb continues.

[0092] When the discharge target range Ra passes the side portion 562 of the third small cap 54 and reaches the small opening 55 of the third small cap 54 at time Tb10, discharge of foamy cleaning liquid Lb onto the discharge target range Ra begins. As a result, the foamy cleaning liquid Lb is discharged onto the small opening 55 of the third small cap 54. Note that, between time Tb9 and time Tb10, discharge of foamy cleaning liquid Lb onto the discharge target range Rb continues, but foamy cleaning liquid Lb is not discharged onto the discharge target range Ra. In other words, while the discharge target range Ra passes the side portion 562 of the third small cap 54, discharge of foamy cleaning liquid Lb onto the discharge target range Ra is stopped.

[0093] At time Tb11, when the discharge target range Rb enters within a predetermined range from the side 561 of the second small cap 54 (in other words, when it approaches the side 561), discharge of the foamy cleaning liquid Lb onto the discharge target range Rb is stopped. In this way, discharge of the foamy cleaning liquid Lb onto the discharge target range Rb is stopped before the discharge target range Rb reaches the side 561 of the second small cap 54. This completes the discharge of the foamy cleaning liquid Lb onto the small opening 55 of the second small cap 54. Note that between time Ta10 and time Ta11, discharge of the foamy cleaning liquid Lb onto the discharge target ranges Ra and Rb continues.

[0094] When the discharge target range Rb passes the side 561 of the second small cap 54 and reaches the space between the second and fourth small caps 54 at time Tb12, discharge of foamy cleaning liquid Lb onto the discharge target range Rb begins. As a result, the foamy cleaning liquid Lb is discharged onto the large opening 52. Note that, between time Ta11 and time Ta12, discharge of foamy cleaning liquid Lb onto the discharge target range Ra continues, but foamy cleaning liquid Lb is not discharged onto the discharge target range Rb. In other words, while the discharge target range Rb passes the side 561 of the second small cap 54, discharge of foamy cleaning liquid Lb onto the discharge target range Rb is stopped.

[0095] At time Tb13, when the discharge target range Rb enters within a predetermined range from the side 562 of the fourth small cap 54 (in other words, when it approaches the side 562), discharge of the foamy cleaning liquid Lb onto the discharge target range Rb is stopped. In this way, discharge of the foamy cleaning liquid Lb onto the discharge target range Rb is stopped before the discharge target range Rb reaches the side 562 of the fourth small cap 54. Note that between time Tb12 and time Tb13, discharge of the foamy cleaning liquid Lb onto the discharge target ranges Ra and Rb continues.

[0096] When the discharge target range Rb passes the side 562 of the fourth small cap 54 and reaches the small opening 55 of the fourth small cap 54 at time Tb14, discharge of foamy cleaning liquid Lb onto the discharge target range Rb begins. As a result, the foamy cleaning liquid Lb is discharged onto the small opening 55 of the fourth small cap 54. Note that, between time Tb13 and time Tb14, discharge of foamy cleaning liquid Lb onto the discharge target range Ra continues, but foamy cleaning liquid Lb is not discharged onto the discharge target range Rb. In other words, while the discharge target range Rb passes the side 562 of the fourth small cap 54, discharge of foamy cleaning liquid Lb onto the discharge target range Rb is stopped.

[0097] At time Tb15, when the discharge target range Ra enters within a predetermined range from the side 561 of the third small cap 54 (in other words, when it approaches the side 561), discharge of the foamy cleaning liquid Lb onto the discharge target range Ra is stopped. In this way, discharge of the foamy cleaning liquid Lb onto the discharge target range Ra is stopped before the discharge target range Ra reaches the side 561 of the third small cap 54. This completes the discharge of the foamy cleaning liquid Lb onto the small opening 55 of the third small cap 54. Note that between time Ta14 and time Ta15, discharge of the foamy cleaning liquid Lb onto the discharge target ranges Ra and Rb continues.

[0098] When the discharge target range Ra passes the side 561 of the third small cap 54 and reaches between the third and fifth small caps 54 at time Tb16, discharge of foamy cleaning liquid Lb onto the discharge target range Ra begins. As a result, the foamy cleaning liquid Lb is discharged onto the large opening 52. Note that, between time Ta15 and time Ta16, discharge of foamy cleaning liquid Lb onto the discharge target range Rb continues, but foamy cleaning liquid Lb is not discharged onto the discharge target range Ra. In other words, while the discharge target range Ra passes the side 561 of the third small cap 54, discharge of foamy cleaning liquid Lb onto the discharge target range Ra is stopped.

[0099] At time Tb17, when the discharge target range Ra enters within a predetermined range from the side 562 of the fifth small cap 54 (in other words, when it approaches the side 562), discharge of the foamy cleaning liquid Lb onto the discharge target range Ra is stopped. In this way, discharge of the foamy cleaning liquid Lb onto the discharge target range Ra is stopped before the discharge target range Ra reaches the side 562 of the fifth small cap 54. Note that between time Tb16 and time Tb17, discharge of the foamy cleaning liquid Lb onto the discharge target ranges Ra and Rb continues.

[0100] When the discharge target range Ra passes the side 562 of the fifth small cap 54 and reaches the small opening 55 of the fifth small cap 54 at time Tb18, discharge of foamy cleaning liquid Lb onto the discharge target range Ra begins. As a result, the foamy cleaning liquid Lb is discharged onto the small opening 55 of the fifth small cap 54. Note that, between time Tb17 and time Tb18, discharge of foamy cleaning liquid Lb onto the discharge target range Rb continues, but foamy cleaning liquid Lb is not discharged onto the discharge target range Ra. In other words, while the discharge target range Ra passes the side 562 of the fifth small cap 54, discharge of foamy cleaning liquid Lb onto the discharge target range Ra is stopped.

[0101] At time Tb19, when the discharge target range Rb enters within a predetermined range from the side 561 of the fourth small cap 54 (in other words, when it approaches the side 561), discharge of the foamy cleaning liquid Lb onto the discharge target range Rb is stopped. In this way, discharge of the foamy cleaning liquid Lb onto the discharge target range Rb is stopped before the discharge target range Rb reaches the side 561 of the fourth small cap 54. This completes the discharge of the foamy cleaning liquid Lb onto the small opening 55 of the fourth small cap 54. Note that between time Ta18 and time Ta19, discharge of the foamy cleaning liquid Lb onto the discharge target ranges Ra and Rb continues.

[0102] When the discharge target range Rb passes the side 561 of the fourth small cap 54 and reaches the space between the fourth small cap 54 and the side 531 of the large cap 51 at time Tb20, discharge of the foamy cleaning liquid Lb onto the discharge target range Rb begins. As a result, the foamy cleaning liquid Lb is discharged onto the large opening 52. Note that, between time Ta19 and time Ta20, the discharge of the foamy cleaning liquid Lb onto the discharge target range Ra continues, but the foamy cleaning liquid Lb is not discharged onto the discharge target range Rb. In other words, while the discharge target range Rb passes the side 561 of the fourth small cap 54, the discharge of the foamy cleaning liquid Lb onto the discharge target range Rb is stopped.

[0103] At time Tb21, when the discharge target range Ra enters within a predetermined range from the side 561 of the fifth small cap 54 (in other words, when it approaches the side 561), discharge of the foamy cleaning liquid Lb onto the discharge target range Ra is stopped. In this way, discharge of the foamy cleaning liquid Lb onto the discharge target range Ra is stopped before the discharge target range Ra reaches the side 561 of the fifth small cap 54. This completes the discharge of the foamy cleaning liquid Lb onto the small opening 55 of the fifth small cap 54. Note that between time Ta20 and time Ta21, discharge of the foamy cleaning liquid Lb onto the discharge target ranges Ra and Rb continues.

[0104] When the discharge target range Ra passes the side 561 of the fifth small cap 54 and reaches between the fifth small cap 54 and the side 531 of the large cap 51 at time Tb22, discharge of foamy cleaning liquid Lb onto the discharge target range Ra begins. As a result, the foamy cleaning liquid Lb is discharged onto the large opening 52. Note that, between time Ta21 and time Ta22, discharge of foamy cleaning liquid Lb onto the discharge target range Rb continues, but foamy cleaning liquid Lb is not discharged onto the discharge target range Ra. In other words, while the discharge target range Ra passes the side 561 of the fifth small cap 54, discharge of foamy cleaning liquid Lb onto the discharge target range Ra is stopped.

[0105] At time Tb23, when the discharge target areas Ra, Rb enter within a predetermined range from the side 531 of the large cap 51 (in other words, when they approach the side 531), the discharge of the foamy cleaning liquid Lb onto the discharge target areas Ra, Rb is stopped. In this way, the discharge of the foamy cleaning liquid Lb onto the discharge target areas Ra, Rb is stopped before the discharge target areas Ra, Rb reach the side 531 of the large cap 51. Note that the discharge of the foamy cleaning liquid Lb onto the discharge target areas Ra, Rb continues between time Ta22 and time Ta23. Then, with the discharge of the foamy cleaning liquid Lb onto the discharge target areas Ra, Rb stopped, the discharge target areas Ra, Rb pass the side 531 of the large cap 51.

[0106] In this way, the foamy cleaning liquid Lb is discharged into the inside of each of the small openings 55 of the multiple (five) small caps 54 and the large opening 52 of the large cap 51 of the maintenance unit 5. In other words, the foamy cleaning liquid Lb is selectively discharged into the small openings 55 and the large openings 52, and is not discharged into areas other than the small openings 55 and the large openings 52 (the peripheral portions 53 of the small caps 54 and the peripheral portions 53 of the large caps 51).

[0107] 9, 10A, and 10B. In this manner, while the maintenance unit 5 is moving from the retracted position Pb to the facing position Pa, the foamy cleaning liquid Lb is discharged into the small openings 55 of the small caps 54 and the large openings 52 of the large caps 51 (step S110). Then, when the maintenance unit 5 arrives at the facing position Pa ("YES" in step S111), capping is performed (step S112).

[0108] 14 is a diagram schematically illustrating the capping performed in the maintenance of FIG. 9. Note that FIG. 14 shows a nozzle presence region N in which a plurality of nozzles 311 exist in the nozzle opening plane 310. When the maintenance unit 5 reaches the facing position Pa in step S111, the maintenance unit 5 faces the web-facing plane 320 of the head unit 3 from below, as shown in FIG. 14. That is, the large opening 52 of the large cap 51 faces the plurality (five) ejection heads 31 arranged on the web-facing plane 320 from below, and includes the plurality of ejection heads 31 in a bottom view. Furthermore, the plurality (five) small caps 54 face the plurality of ejection heads 31 from below, respectively, and the small openings 55 of the small caps 54 face the plurality of nozzles 311 in the nozzle opening plane 310 of the opposing ejection head 31, and include the plurality of nozzles 311 in a bottom view.

[0109] Also, as shown in Figure 14, the peripheral edge 53 of the large cap 51 protrudes more toward the head unit 3 than the peripheral edge 56 of the small cap 54; in other words, the distance between the peripheral edge 56 of the small cap 54 and the head unit 3 is longer than the distance between the peripheral edge 53 of the large cap 51 and the head unit 3.

[0110] A layer of foamy cleaning liquid Lb is formed in the small opening 55 facing the multiple nozzles 311 (in other words, the nozzle presence region N) of the nozzle opening plane 310. That is, the layer of foamy cleaning liquid Lb faces the multiple nozzles 311 from below. The liquid level of the foamy cleaning liquid Lb in the small opening 55 of the small cap 54 is lower than the height of the peripheral edge 56 of the small cap 54.

[0111] Furthermore, a layer of foamy cleaning liquid Lb is formed in a small cap outer region O outside the small cap 54 of the large opening 52. The liquid level of the foamy cleaning liquid Lb in the small cap outer region O is lower than the height of the peripheral portion 53 of the large cap 51 and is also lower than the height of the peripheral portion 56 of the small cap 54.

[0112] 14, before capping, the peripheral edge 53 of the large cap 51 is spaced downward from the web-facing plane 320 of the head unit 3. On the other hand, as shown in the "During Capping" column of Fig. 14, during capping, the peripheral edge 53 of the large cap 51 is in close contact with the web-facing plane 320 of the head unit 3. Note that even during capping, the peripheral edge 56 of the small cap 54 is spaced from the nozzle opening plane 310 of the ejection head 31, and a gap is provided between the peripheral edge 56 of the small cap 54 and the nozzle opening plane 310 of the ejection head 31.

[0113] Furthermore, during capping, the layer of foamy cleaning liquid Lb formed in the small opening 55 of the small cap 54 is spaced downward from the nozzle opening plane 310 facing the small opening 55, thereby preventing contact between the foamy cleaning liquid Lb in the small opening 55 and the nozzle opening plane 310. Such contact prevention can be achieved, for example, by setting the amount of foamy cleaning liquid Lb discharged into the small opening 55 in step S110 so that the foamy cleaning liquid Lb does not overflow from the small opening 55. More specifically, the amount of foamy cleaning liquid Lb discharged into the small opening 55 in step S110 depends on the amount of foamy cleaning liquid Lb discharged per unit time from the cleaning liquid nozzle 85 (discharge rate) and the speed at which the small opening 55 moves relative to the cleaning liquid nozzle 85 (movement speed). Therefore, step S110 can be performed based on the discharge rate and movement speed that are preset according to the capacity of the small opening 55.

[0114] Furthermore, the layer of foamed cleaning liquid Lb formed in the small cap outer region O of the large cap 51 is spaced downward from the web-facing plane 320 (or the nozzle opening plane 310) facing the small cap outer region O. Setting the amount of foamed cleaning liquid Lb in such small cap outer region O can be carried out using the same concept as setting the amount of foamed cleaning liquid Lb in the small opening 55 described above.

[0115] 9, after capping is performed in step S112, the process returns to step S101 to check whether a print command has been issued. If the time spent waiting for a print command in step S101 is long, the foamy cleaning liquid Lb will disappear (defoam). On the other hand, if the time spent waiting for a print command in step S101 is short, the foamy cleaning liquid Lb in the small cap 54 may not completely disappear and may remain. In response to this, by performing the above-mentioned steps S104 and S107 (foam removal process), the cleaning liquid Lo is ejected into the small cap 54 (step S104), and the cleaning liquid Lo is further discharged from the small cap 54 (step S107). As a result, the foamy cleaning liquid Lb remaining in the small cap 54 is discharged together with the cleaning liquid Lo.

[0116] In the embodiment described above, the nozzles 311 of the ejection head 31 can be moistened by the foamy cleaning liquid Lb in the maintenance unit 5 (cap unit) that comes into contact with the head unit 3 for capping (step S112). In particular, capping is performed (step S112) after the foamy cleaning liquid Lb is ejected into the maintenance unit 5 (step S110) so that the foamy cleaning liquid Lb in the maintenance unit 5 is separated from the nozzle opening plane 310 (ink ejection surface) when capping is performed (FIG. 14). This makes it possible to prevent air bubbles contained in the foamy cleaning liquid Lb from entering the nozzles 311. In this way, it is possible to moisturize the nozzles 311 while preventing air bubbles from entering the nozzles 311.

[0117] Furthermore, in this embodiment, the cleaning liquid nozzle 85 discharges the foamy cleaning liquid Lb directly into the small opening 55 and the large opening 52. By discharging the foamy cleaning liquid Lb directly in this manner without going through another member, it is possible to prevent the foamy cleaning liquid Lb from adhering to other members (such as the head unit 3), and in turn to prevent air bubbles in the foamy cleaning liquid Lb adhering to the nozzle opening plane 310 from entering the nozzle 311.

[0118] The maintenance unit 5 also has a large cap 51 having a large opening 52 corresponding to the head unit 3, and a small cap 54 having a small opening 55 that is smaller than the large opening 52 and corresponds to the nozzle opening plane 310, with the small cap 54 being disposed inside the large opening 52. The large cap 51 has a periphery 53 (large opening periphery) that defines the large opening 52, and the small cap 54 has a periphery 56 (small opening periphery) that defines the small opening 55. During capping, the large opening 52 faces the head unit 3 and contacts the head unit 3 at its periphery 53, and the small opening 55 faces the nozzle opening plane 310 ( FIG. 14 ). In response to this, the cleaning liquid supply unit 8 ejects foamy cleaning liquid Lb inside the large opening 52 (large opening 52 / small opening 55). In this configuration, the foamy cleaning liquid Lb inside the large cap 51 that comes into contact with the head unit 3 due to capping can moisturize the nozzles 311 of the ejection heads 31 of the head unit 3. Furthermore, by ejecting the foamy cleaning liquid Lb onto such a maintenance unit 5 as described above (step S110) and then performing capping (step S112), it is possible to moisturize the nozzles 311 while suppressing the intrusion of air bubbles into the nozzles 311.

[0119] In particular, in step S110, foamy cleaning liquid Lb is ejected into the small opening 55 of the maintenance unit 5 that performs capping so that the foamy cleaning liquid Lb in the small opening 55 moves away from the nozzle opening plane 310 (FIG. 14). With this configuration, the foamy cleaning liquid Lb in the small opening 55 that faces the nozzle opening plane 310 inside the large cap 51 that comes into contact with the head unit 3 for capping can moisturize the nozzles 311 that open at the nozzle opening plane 310. At this time, the foamy cleaning liquid Lb is ejected into the small opening 55 so that the foamy cleaning liquid Lb in the small opening 55 moves away from the nozzle opening plane 310 during capping (step S110), and then capping is performed (step S112). Therefore, it is possible to moisturize the nozzles 311 while suppressing the intrusion of air bubbles into the nozzles 311.

[0120] The cleaning liquid supply unit 8 is also provided with a horizontal drive unit 61 that drives the maintenance unit 5 toward the other side X2 in the X direction (drive direction). The maintenance unit 5 has two cap rows C54 (first and second cap rows) configured at different positions in the Y direction (width direction) perpendicular to the X direction. One cap row C54 (first cap row) is provided with a cleaning liquid nozzle 85 (first outlet) that discharges foamy cleaning liquid Lb into a discharge target range Ra, and the other cap row C54 is provided with a cleaning liquid nozzle 85 (second outlet) that discharges foamy cleaning liquid Lb into a discharge target range Rb. As the horizontal drive unit 61 drives, the one cap row C54 moves through the discharge target range Ra toward the other side X2, and the cleaning liquid nozzle 85 discharges foamy cleaning liquid Lb into the small openings 55 of the small caps 54. Similarly, foamy cleaning liquid Lb is discharged from the cleaning liquid nozzle 85 into the small openings 55 of the small caps 54 in the other cap row C54, which moves through the discharge target range Rb to the other side X2 as the horizontal drive unit 61 drives. At this time, as shown in FIGS. 13A to 13E , the leading (first) small cap 54 (first leading cap) of the cap row C54 moving through the discharge target range Ra and the leading (second) small cap 54 (second leading cap) of the cap row C54 moving through the discharge target range Rb are located at different positions in the X direction. In response to this, the timing (time Tb4) at which the cleaning liquid nozzle 85 corresponding to the discharge target range Ra starts discharging the foamy cleaning liquid Lb onto the first small cap 54 differs from the timing (time Tb6) at which the cleaning liquid nozzle 85 corresponding to the discharge target range Rb starts discharging the foamy cleaning liquid Lb onto the second small cap 54, depending on the difference in the positions of the first and second small caps 54.

[0121] That is, to accommodate the difference in position in the X direction between the first small cap 54 and the second small cap 54, the time Tb4 at which the cleaning liquid nozzle 85 corresponding to the discharge target range Ra starts to discharge the foamy cleaning liquid Lb onto the first small cap 54 is different from the time Tb6 at which the cleaning liquid nozzle 85 corresponding to the discharge target range Rb starts to discharge the foamy cleaning liquid Lb onto the second small cap 54. This makes it possible to accurately discharge the foamy cleaning liquid Lb onto each of the small caps 54 in the two cap rows C54.

[0122] The cleaning liquid supply unit 8 also has a cleaning liquid nozzle 85 (discharge port) that discharges foamy cleaning liquid Lb into a predetermined discharge target range R (Ra, Rb). The cleaning liquid nozzle 85 discharges foamy cleaning liquid Lb while the inside of the small opening 55 passes through the discharge target range R due to the drive of the horizontal drive unit 61 (drive unit), but does not discharge foamy cleaning liquid Lb while the peripheral edge 56 passes through the discharge target range R due to the drive of the horizontal drive unit 61 (FIGS. 13A to 13E). With this configuration, the foamy cleaning liquid Lb can be discharged into the small opening 55 of the small cap 54 while avoiding the peripheral edge 56 (side portions 561, 562) of the small cap 54. Therefore, the foamy cleaning liquid Lb adhering to the peripheral edge 56 adheres to the nozzle opening plane 310, and further, air bubbles contained in the foamy cleaning liquid Lb can be prevented from entering the nozzle 311.

[0123] In addition, in the Y direction (width direction), the discharge target range R (Ra, Rb) is included inside the small opening 55 (FIGS. 11A and 13A). With this configuration, the foamy cleaning liquid Lb can be discharged to the small opening 55 of the small cap 54 while avoiding the peripheral edge 56 (side portions 563, 564) of the small cap 54. Therefore, the foamy cleaning liquid Lb adhering to the peripheral edge 56 can be prevented from adhering to the nozzle opening plane 310, and further, air bubbles contained in the foamy cleaning liquid Lb can be prevented from entering the nozzle 311.

[0124] Incidentally, if capping (step S112) is repeated in a short period of time, it is conceivable that the next foamy cleaning liquid Lb will be added to the small opening 55 before the foamy cleaning liquid Lb in the small opening 55 disappears (before the bubbles are destroyed), and the amount of foamy cleaning liquid Lb in the small opening 55 will increase with each capping (step S112), and the foamy cleaning liquid Lb may reach the nozzle opening plane 310. In such a case, there is a risk that air bubbles will enter the nozzle 311 and interfere with the ejection of ink from the nozzle 311.

[0125] In response to this, the cleaning liquid supply unit 8 (rinse liquid discharge unit) discharges cleaning liquid Lo (rinse liquid), which is a liquid that does not contain bubbles, into the small opening 55. The printing apparatus 1 is also equipped with a drainage mechanism 65 (liquid discharge unit) that discharges the cleaning liquid Lo from the small opening 55. The bubble removal process (steps S104 and S107) in which the cleaning liquid supply unit 8 discharges the cleaning liquid Lo into the small opening 55 and then the drainage mechanism 65 discharges the cleaning liquid Lo from the small opening 55 is performed before step S110 in which foamy cleaning liquid Lb is discharged into the small opening 55. This configuration effectively prevents the above-mentioned problem, which is caused by repeated capping (step S112) in a short period of time, from occurring, in which bubbles contained in the foamy cleaning liquid Lb that has reached the nozzle orifice plane 310 enter the nozzles 311 and interfere with the discharge of ink from the nozzles 311.

[0126] The type of rinse liquid discharged into the small opening 55 in step S104 is not limited to the cleaning liquid Lo, and may be, for example, water.

[0127] Furthermore, the cleaning liquid supply unit 8 discharges the foamed cleaning liquid Lb into the small cap outer region O that is inside the large opening 52 of the large cap 51 and outside the small cap 54. The foamed cleaning liquid Lb discharged into the small cap outer region O in the large opening 52 in this manner can thoroughly moisturize the nozzle 311.

[0128] In particular, when capping is performed, the peripheral edge 56 of the small cap 54 is separated from the nozzle opening plane 310 (FIG. 14). In this configuration, when capping is performed, moisture supplied by the foamy cleaning liquid Lb discharged into the small cap outer region O enters the small opening 55 through the gap between the peripheral edge 56 of the small cap 54 and the nozzle opening plane 310, and can contribute to moisturizing the nozzle 311.

[0129] The maintenance unit 5 is movable between a facing position Pa and a retracted position Pb, which are mutually different positions. When positioned at the facing position Pa, the maintenance unit 5 faces the head unit 3, while when positioned at the retracted position Pb, the maintenance unit 5 retracts in the X direction from the head unit 3. In particular, the maintenance unit 5 performs capping at the facing position Pa (step S112), and is positioned at the retracted position Pb while the ejection head 31 ejects ink onto the web W (print medium) to print an image on the web W (steps S106 to S108). Meanwhile, the cleaning liquid supply unit 8 (its cleaning liquid nozzle 85) is provided between the retracted position Pb and the facing position Pa, and ejects foamy cleaning liquid Lb onto the maintenance unit 5 as it moves from the retracted position Pb to the facing position Pa (step S110). With this configuration, the period during which the maintenance unit 5 moves from the retracted position Pb to the facing position Pa can be effectively used to eject foamy cleaning liquid Lb onto the maintenance unit 5 for capping.

[0130] Furthermore, the cleaning liquid supply unit 8 ejects the cleaning liquid Lo onto the maintenance unit 5 as it moves from the facing position Pa to the retracted position Pb (step S104). In this configuration, since the maintenance unit 5 retreats to the retracted position Pb when the ejection head 31 starts printing, the cleaning liquid Lo can be ejected onto the maintenance unit 5 by effectively utilizing the period during which the maintenance unit 5 moves from the facing position Pa to the retracted position Pb.

[0131] As described above, in this embodiment, the printing device 1 corresponds to an example of the "printing device" of the present invention, the head unit 3 corresponds to an example of the "head unit" of the present invention, the ejection head 31 corresponds to an example of the "ejection head" of the present invention, the nozzle opening plane 310 corresponds to an example of the "ink ejection surface" of the present invention, the nozzle 311 corresponds to an example of the "nozzle" of the present invention, the head holding member 32 corresponds to an example of the "head holding member" of the present invention, the maintenance unit 5 corresponds to an example of the "cap unit" of the present invention, the large cap 51 corresponds to an example of the "large cap" of the present invention, the large opening 52 corresponds to an example of the "large opening" of the present invention, the peripheral portion 53 corresponds to an example of the "large opening peripheral portion" of the present invention, the small cap 54 corresponds to an example of the "small cap" of the present invention, the small opening 55 corresponds to an example of the "small opening" of the present invention, the peripheral portion 56 corresponds to an example of the "small opening peripheral portion" of the present invention, and the horizontal driving unit 61 corresponds to an example of the "driving unit" of the present invention. the drainage mechanism 65 corresponds to an example of a "liquid discharge section" of the present invention; the two cleaning liquid supply sections 8 function as "cleaning liquid discharge sections" of the present invention, and the two cleaning liquid supply sections 8 cooperate to function as "rinsing liquid discharge sections" of the present invention; the cleaning liquid nozzle 85 corresponds to an example of an "discharge port," "first discharge port," and "second discharge port" of the present invention; the two cap rows C54 correspond to an example of a "first and second cap rows" of the present invention; the foamy cleaning liquid Lb corresponds to an example of a "foamy cleaning liquid" of the present invention; the cleaning liquid Lo corresponds to an example of a "rinsing liquid" of the present invention; the small cap outer region O corresponds to an example of a "small cap outer region" of the present invention; the opposing position Pa corresponds to an example of an "opposing position" of the present invention; the retracted position Pb corresponds to an example of a "retracted position" of the present invention; the discharge target range R corresponds to an example of a "discharge target range" of the present invention; the X direction corresponds to an example of a "driving direction" of the present invention; and the Y direction corresponds to an example of a "width direction" of the present invention.

[0132] The present invention is not limited to the above-described embodiment, and various modifications can be made without departing from the spirit of the present invention. For example, the specific configuration of the cleaning liquid supply unit 8 may be changed. FIG. 15 is a diagram schematically illustrating the configuration of a second example of the cleaning liquid supply unit. The second example of FIG. 15 differs from the first example of FIG. 5 in that an air stone 831 is arranged in the mixing region 83.

[0133] In the "bubble mode," when the undiluted liquid discharge unit 81 discharges the cleaning liquid Lo while the air discharge unit 82 discharges air, the cleaning liquid Lo discharged from the undiluted liquid discharge unit 81 and the air discharged from the air discharge unit 82 are mixed in the mixing region 83. At this time, air A atomized by the air stone 831 is mixed with the cleaning liquid Lo, and a foamy cleaning liquid Lb containing fine bubbles (= cleaning liquid Lo + air A) is generated. This foamy cleaning liquid Lb is then discharged from the opening 851 of the cleaning liquid nozzle 85. In the "rinse mode," when the undiluted liquid discharge unit 81 discharges the cleaning liquid Lo while the air discharge unit 82 stops discharging air, the cleaning liquid Lo discharged from the undiluted liquid discharge unit 81 flows into the cleaning liquid nozzle 85 via the air stone 831 in the mixing region 83 and is discharged from the cleaning liquid nozzle 85. That is, in the second example as well, the cleaning liquid supply unit 8 executes the bubble mode to eject foamy cleaning liquid Lb containing bubbles from the cleaning liquid nozzle 85, and executes the rinse mode to eject cleaning liquid Lo not containing bubbles from the cleaning liquid nozzle 85.

[0134] Alternatively, instead of the air stone 831, a microbubble generator that generates microbubbles or a nanobubble generator that generates nanobubbles may be provided, and a foamy cleaning liquid Lb containing microbubbles or nanobubbles may be discharged from the cleaning liquid nozzle 85 in the bubble mode, while a cleaning liquid Lo that does not contain bubbles may be discharged from the cleaning liquid nozzle 85 in the rinse mode.

[0135] 16 is a diagram schematically illustrating the configuration of a third example of a cleaning liquid supply unit. In the third example of the cleaning liquid supply unit 8, two lines of pipes 861 and 862 are provided in parallel, and each of the pipes 861 and 862 is connected to a cleaning liquid nozzle 85. Of the pipes 861 and 862, a bubble generation unit 87 is attached to the pipe 861. The bubble generation unit 87 has a plurality of mesh filters 871 arranged in series, and bubbles are generated when the cleaning liquid Lo passes through the mesh filters 871. In addition, an electromagnetic valve 88 is provided between the pipes 861 and 862 and the undiluted liquid discharge unit 81, and the electromagnetic valve 88 switches the connection destination of the undiluted liquid discharge unit 81 between the pipes 861 and 862.

[0136] In the bubble mode, the solenoid valve 88 connects the concentrate discharger 81 to the pipe 861 and blocks the connection between the concentrate discharger 81 and the pipe 862. Therefore, the cleaning liquid Lo discharged from the concentrate discharger 81 flows into the bubble generator 87, and cleaning liquid Lo containing bubbles, i.e., foamy cleaning liquid Lb, is generated in the bubble generator 87. The foamy cleaning liquid Lb thus generated flows from the bubble generator 87 into the cleaning liquid nozzle 85 and is discharged from the cleaning liquid nozzle 85.

[0137] In the rinse mode, the solenoid valve 88 connects the undiluted liquid discharger 81 to the pipe 862 and blocks the connection between the undiluted liquid discharger 81 and the pipe 861. Therefore, the cleaning liquid Lo discharged from the undiluted liquid discharger 81 bypasses the bubble generator 87 and is discharged from the cleaning liquid nozzle 85.

[0138] In the above embodiment, two types of liquid, foamy cleaning liquid Lb and cleaning liquid Lo, are discharged from the cleaning liquid supply unit 8 to the maintenance unit 5. However, it is also possible to configure the system so that two types of foamy cleaning liquid Lb with different bubble states are discharged to the maintenance unit 5. Fig. 17 is a diagram in the form of a table showing the operation of discharging two types of foamy cleaning liquid by the cleaning liquid supply unit of Fig. 5.

[0139] As shown in Fig. 17, in the "first bubble mode," while the stock solution discharger 81 is discharging the cleaning solution Lo, the air discharger 82 discharges air A at a velocity V1 (flow velocity), thereby generating a foamy cleaning solution Lb1 containing bubbles. In the "second bubble mode," while the stock solution discharger 81 is discharging the cleaning solution Lo, the air discharger 82 discharges air A at a velocity V2 (flow velocity), thereby generating a foamy cleaning solution Lb2. Here, velocity V1 is faster than velocity V2. Therefore, the bubbles contained in the foamy cleaning solution Lb1 are finer (i.e., have a smaller diameter) than the bubbles contained in the foamy cleaning solution Lb2.

[0140] 5, the cleaning liquid supply unit 8 has an undiluted liquid discharge unit 81 that supplies cleaning liquid Lo that does not contain bubbles, and an air discharge unit 82 that supplies air A. The cleaning liquid supply unit 8 changes the speed at which air A discharged from the air discharge unit 82 is mixed with the cleaning liquid Lo discharged from the undiluted liquid discharge unit 81, thereby selectively generating foamy cleaning liquid Lb1 and foamy cleaning liquid Lb2 with different bubble states and discharging them onto the wiper 54. With this configuration, the foamy cleaning liquid Lb1 and foamy cleaning liquid Lb2 can be easily used selectively by changing the speed at which air A is mixed with the cleaning liquid Lo (undiluted liquid).

[0141] With this configuration, foamy cleaning liquid Lb1 (first foamy cleaning liquid) and foamy cleaning liquid Lb2 (second foamy cleaning liquid) with different bubble states can be supplied to the maintenance unit 5. This allows a variety of processes to be performed on the maintenance unit 5. In other words, the size (diameter) of the bubbles contained in the foamy cleaning liquid Lb2 is larger than the size (diameter) of the bubbles contained in the foamy cleaning liquid Lb1. Such coarse bubbles (large diameter bubbles) of the foamy cleaning liquid Lb2 tend to disappear more quickly than the fine bubbles (small diameter bubbles) of the foamy cleaning liquid Lb1. Therefore, the bubble mode of step S110 may be modified as follows.

[0142] In this modification, in the bubble mode of step S110, the cleaning liquid nozzle 85 discharges foamy cleaning liquid Lb2 containing large bubbles into the small opening 55 of the small cap 54, and the cleaning liquid nozzle 85 discharges foamy cleaning liquid Lb1 containing small bubbles into the small cap outer region O of the large cap 51. That is, the diameter (size) of the bubbles contained in the foamy cleaning liquid Lb2 discharged into the small opening 55 is larger than the diameter (size) of the bubbles contained in the foamy cleaning liquid Lb1 discharged into the small cap outer region O. As a result, the foamy cleaning liquid Lb2 containing relatively coarse bubbles is discharged into the small opening 55. Therefore, the foamy cleaning liquid Lb2 in the small opening 55 disappears relatively quickly, and the foamy cleaning liquid Lb2 can be prevented from reaching the nozzle opening plane 310 as capping is repeated. Moreover, the foamy cleaning liquid Lb1 containing relatively fine bubbles is discharged to the small cap outer region O inside the large opening 52 of the large cap 51 and outside the small cap 54. Therefore, the foamy cleaning liquid Lb1 discharged to the small cap outer region O inside the large opening 52 remains for a long time, contributing to moisturizing the nozzle 311. In this way, the nozzle 311 can be thoroughly moisturized while accurately suppressing the intrusion of bubbles into the nozzle 311.

[0143] 9 does not need to include the foam removal process in steps S104 and S107. As a result, there is no need to include the drainage mechanism 65. However, it is of course possible to use the foam cleaning liquid Lb1 and the foam cleaning liquid Lb2 shown in this modification in combination with the foam removal process in steps S104 and S107.

[0144] Alternatively, the relationship between the bubble diameters may be reversed. That is, in the bubble mode of step S110, the cleaning liquid nozzle 85 may discharge foamy cleaning liquid Lb1 containing small bubbles toward the small opening 55 of the small cap 54, and the cleaning liquid nozzle 85 may discharge foamy cleaning liquid Lb2 containing large bubbles toward the small cap outer region O of the large cap 51.

[0145] Furthermore, the number and arrangement of the small caps 54 are not limited to the above example and can be changed in various ways. Therefore, the number of small caps 54 may be one or more, and the small caps 54 may be arranged in a line.

[0146] Furthermore, in order to move the maintenance unit 5 in the X direction relative to the cleaning liquid supply unit 8, it is not necessary to drive the maintenance unit 5 in the X direction as described above, and the cleaning liquid supply unit 8 may be driven in the X direction. In other words, it is sufficient to configure at least one of the maintenance unit 5 and the cleaning liquid supply unit 8 to be driven in the X direction.

[0147] 9, the bubble removal processes in steps S104 and S107 are not essential and may be omitted as appropriate. Alternatively, the bubble removal processes in steps S104 and S107 may be performed if the waiting time from when capping is performed in step S112 until the print command is confirmed in step S101 is equal to or greater than a predetermined threshold time, and may not be performed if the waiting time is less than the predetermined threshold time.

[0148] Furthermore, when discharging the foamy cleaning liquid Lb onto the small cap 54 in the bubble mode in step S110, the foamy cleaning liquid Lb is discharged onto the discharge target range R while the discharge target range R passes inside the small opening 55 of the small cap 54, and the discharge of the foamy cleaning liquid Lb onto the discharge target range R is stopped while the discharge target range R passes through the peripheral portion 56 of the small cap 54, thereby preventing the foamy cleaning liquid Lb from adhering to the peripheral portion 56 of the small cap 54. However, for example, the foamy cleaning liquid Lb may be continuously discharged onto the discharge target range R throughout the period when the discharge target range R passes between both ends of the cap row C54. In this case, the foamy cleaning liquid Lb will also adhere to the peripheral portion 56 of the small cap 54.

[0149] In addition, when the foam cleaning liquid Lb is ejected to the maintenance unit 5 in the bubble mode of step S110, the foam cleaning liquid Lb may be ejected to one of the large cap 51 and the small cap 54, and not to the other.

[0150] Furthermore, it is not necessary for the maintenance unit 5 to have both the large cap 51 and the small cap 54, and the maintenance unit 5 may be configured to have one of the large cap 51 and the small cap 54 and not the other.

[0151] Also, a liquid absorbing member such as a sponge may be placed inside the small opening 55 of the small cap 54. In this case, a layer of the foamy cleaning liquid Lb will be formed on the liquid absorbing member. [Industrial Applicability]

[0152] The present invention is applicable to all techniques for moisturizing nozzles by capping an ejection head that ejects ink from nozzles that open on an ink ejection surface with a cap unit. [Explanation of symbols]

[0153] 1...Printing device 3...Head unit 31...Discharge head 310...Nozzle opening plane (ink ejection surface) 311...Nozzle 32...Head holding member 5...Maintenance unit (cap unit) 51...Large Cap 52...Large opening 53...Periphery (large opening periphery) 54...Small cap 55...Small opening 56...periphery (small opening periphery) 61...Horizontal drive unit (drive unit) 65...Drainage mechanism (liquid discharge part) 8...Cleaning liquid supply unit (cleaning liquid discharge unit, rinse liquid discharge unit) 85...Cleaning liquid nozzle (outlet, first outlet, second outlet) C54...Cap row (1st and 2nd cap row) Lb...Foam cleaning solution (Foam cleaning solution) Lo...cleaning solution (rinse) O...Small cap outer area Pa: Opposite position Pb…Evacuation position R...Discharge target range X...X direction (drive direction) Y...Y direction (width direction)

Claims

1. a head unit having an ejection head that ejects ink from nozzles that open on an ink ejection surface and a head holding member that holds the ejection head; a cap unit having a cap including a peripheral portion and an opening that is a hole that opens upward and is defined by the peripheral portion, the cap unit facing the nozzles and coming into contact with the head unit to cap the nozzles; a foam liquid generating unit that generates a foam liquid, which is a raw liquid containing bubbles, by mixing bubbles with the raw liquid; a liquid nozzle that discharges the foam liquid to the cap unit before the capping is performed by the cap unit; A printing device comprising: A printing device in which the liquid nozzle ejects the foam liquid toward the cap excluding the peripheral portion, thereby ejecting the foam liquid toward the cap unit so that the foam liquid in the cap unit that performs the capping is separated from the ink ejection surface.

2. the cap unit has a large cap having a large opening that opens corresponding to the head unit, the opening of the cap is a small opening that is smaller than the large opening and opens in correspondence with the ink ejection surface, the cap is a small cap having the small opening, the small cap is disposed inside the large opening; the large cap has a large opening periphery that is a periphery that defines the large opening, the small cap has a small opening periphery that is a periphery that defines the small opening, When the capping is performed, the large opening faces the head unit, the periphery of the large opening contacts the head unit, and the small opening faces the ink ejection surface, The printing device according to claim 1 , wherein the liquid nozzle ejects the foam liquid toward the inside of the large opening.

3. the liquid nozzle discharges the foam liquid into the small opening; The printing apparatus according to claim 2 , wherein the foam liquid in the small opening of the cap unit that performs the capping is spaced apart from the ink ejection surface.

4. a drive unit that drives the cap unit relative to the liquid nozzle in a drive direction, In the cap unit, a first cap row and a second cap row each having the small caps arranged in the driving direction are arranged at different positions in a width direction perpendicular to the driving direction, the liquid nozzle has a first discharge port provided corresponding to the first cap row and a second discharge port provided corresponding to the second cap row; the first discharge port discharges the foam liquid into the small opening of the small cap in the first cap row that moves in the drive direction as the drive unit is driven; the second discharge port discharges the foam liquid into the small opening of the small cap in the second cap row that moves in the drive direction as the drive unit is driven, a first leading cap at the front in the driving direction among the small caps arranged in the first cap row in the driving direction and a second leading cap at the front in the driving direction among the small caps arranged in the second cap row in the driving direction are provided at different positions in the driving direction, A printing device as described in claim 3, wherein the timing at which the first ejection outlet starts ejecting the foamy liquid onto the first leading cap and the timing at which the second ejection outlet starts ejecting the foamy liquid onto the second leading cap differ depending on the difference in the positions of the first leading cap and the second leading cap in the drive direction.

5. a drive unit that drives the cap unit relative to the liquid nozzle in a drive direction, A printing device as described in claim 3, wherein the liquid nozzle has an outlet that ejects the foamy liquid toward a predetermined target range, and ejects the foamy liquid from the outlet during a period when the inside of the small opening passes through the target range due to driving of the drive unit, and does not eject the foamy liquid from the outlet during a period when the peripheral portion of the small opening passes through the target range due to driving of the drive unit.

6. The printing device according to claim 5 , wherein the ejection target range is included inside the small opening in the width direction perpendicular to the drive direction.

7. the liquid nozzle discharges the foam liquid into a small cap external region that is inside the large opening of the large cap and outside the small cap; The foam liquid, which is obtained by mixing the original liquid with air discharged from the air discharge portion by the foam liquid generating portion at a speed V1, is discharged into the outside area of ​​the small cap, A printing device as described in any one of claims 3 to 6, wherein the foam liquid is mixed with the original liquid and ejected by the foam liquid generating unit from the air ejection unit at a speed V2 slower than the speed V1, and the foam liquid is ejected into the small opening.

8. The printing device according to claim 2 , wherein the liquid nozzle ejects the foam liquid into an external area of ​​the small cap that is inside the large opening of the large cap and outside the small cap.

9. 9. The printing apparatus according to claim 7, wherein the peripheral edge of the small opening is spaced apart from the ink ejection surface when the capping is performed.

10. the cap unit is movable between a facing position and a retracted position, which are different from each other, and faces the head unit when positioned at the facing position, and does not face the head unit when positioned at the retracted position; the liquid nozzle is provided between the retracted position and the facing position, the cap unit performs the capping at the opposing position, and is positioned at the retracted position while the ejection head ejects ink onto the print medium to print an image on the print medium; The printing apparatus according to claim 1 , wherein the liquid nozzle ejects the foam liquid onto the cap unit as it moves from the retracted position to the opposing position.

11. a rinse liquid discharge unit that discharges the rinse liquid, which is a liquid that does not contain bubbles, onto the cap unit; a liquid discharge part that discharges the rinse liquid from the cap unit; Furthermore, A printing device described in any one of claims 1 to 9, wherein a foam removal process in which the rinse liquid ejection unit ejects the rinse liquid into the cap unit and then the liquid ejection unit ejects the rinse liquid from the cap unit is performed before ejecting the foamy liquid into the cap unit.

12. The printing apparatus according to claim 11 , wherein the rinse liquid is the undiluted liquid that does not contain air bubbles.

13. the cap unit is movable between a facing position and a retracted position, which are different from each other, and faces the head unit when positioned at the facing position, and does not face the head unit when positioned at the retracted position; the rinse liquid discharge part is provided between the retracted position and the facing position, the cap unit performs the capping at the opposing position, and is positioned at the retracted position while the ejection head ejects ink onto the print medium to print an image on the print medium; The printing apparatus according to claim 11 or 12, wherein the rinse liquid discharger discharges the rinse liquid onto the cap unit that moves from the facing position to the retracted position.

14. the liquid nozzle is provided between the retracted position and the facing position, The printing apparatus according to claim 13 , wherein the liquid nozzle ejects the foam liquid toward the cap unit as it moves from the retracted position to the opposing position.

15. A foam liquid generating step of generating a foam liquid, which is a foam liquid containing bubbles, by mixing bubbles into the raw liquid; discharging the foam liquid into a cap unit; a step of performing capping by bringing the cap unit into contact with the head unit while facing the nozzles of the head unit, the head unit having an ejection head that ejects ink from nozzles that open on an ink ejection surface and a head holding member that holds the ejection head; Equipped with A nozzle moisturizing method in which the foam liquid is ejected into the cap unit that performs the capping so that the foam liquid in the cap unit is separated from the ink ejection surface, and the nozzle is moistened by the moisture supplied by the foam liquid ejected into the cap unit.

Images