JP7386527B2 - Inkjet head cleaning method and inkjet head cleaning device - Google Patents

Description

The present invention relates to an inkjet head cleaning method and an inkjet head cleaning device.

In an inkjet drawing device, as the printing operation continues, ink dust (ink mist) generated during ink ejection adheres to the surface of the nozzle surface formed by the multiple ink ejection nozzles of the inkjet head, causing contamination. This may cause abnormalities in the ejection state, such as nozzle clogging and misalignment of the ejection direction.

Therefore, in inkjet drawing apparatuses, various methods are generally used to clean the nozzle surface of the inkjet head in order to maintain normal ejection of ink.

For example, Patent Document 1 discloses a configuration in which a nozzle surface is wiped using two rubber blades having different hardnesses.

Japanese Patent Application Publication No. 9-290511

Incidentally, ink that adheres to the nozzle surface of an inkjet head and contaminates the nozzle surface may dry naturally due to evaporation of the solvent.
This natural drying causes the ink adhering to the nozzle surface to thicken and dry, resulting in a problem that the ink adheres closely to the nozzle surface and is difficult to remove. This problem promotes ink ejection abnormalities such as clogging and deflection of the nozzles of the inkjet head.

Furthermore, this problem occurs particularly prominently among inks that tend to dry naturally, and particularly in aqueous inks that use water as a solvent and alcoholic inks that use alcohol as a solvent. Furthermore, this problem occurs particularly prominently among aqueous inks, such as aqueous latex inks in which pigments and resins are dispersed in a solvent, because the ink tends to increase in viscosity.

In this case, for example, the cleaning method using a rubber blade disclosed in Patent Document 1 cannot completely remove ink that has dried and thickened on the nozzle surface, making it difficult to improve the ejection abnormality of the inkjet head.

The present invention has been made in view of the above problems, and is intended to solve the above problems, reliably remove contamination such as ink mist generated on the nozzle surface of an inkjet head, and ensure normal ink ejection by the inkjet head. An object of the present invention is to provide an inkjet head cleaning method and an inkjet head cleaning device that can be maintained.

In order to achieve the above object, the inventor of the present invention discovered the following configuration as a result of diligent efforts.

That is, in the present invention, a method for cleaning an inkjet head having a nozzle surface on which a plurality of nozzles for ejecting liquid are arranged is as follows:
a first wiping step of wiping the nozzle surface by relative movement between the first wiper and the inkjet head while applying a maintenance liquid to the first wiper;
an ink purge step of forcibly discharging ink from the plurality of nozzles after performing the first wiping step;
After performing the ink purging step, the method includes a second wiping step of wiping the nozzle surface by relative movement of a second wiper and the inkjet head.

Further, in the present invention, in an inkjet head cleaning device having a nozzle surface on which a plurality of nozzles for ejecting liquid are arranged,
a first wiper having means for retaining liquid;
maintenance liquid applying means for applying maintenance liquid to the first wiper;
an ink purge unit for forcibly discharging ink from the plurality of nozzles after wiping the nozzle surface by relative movement between the first wiper to which the maintenance liquid has been applied by the maintenance liquid applying unit and the inkjet head;
An inkjet head cleaning device comprising: a second wiper that wipes the nozzle surface by moving relative to the inkjet head after the ink is forcibly discharged from the plurality of nozzles by the ink purge means. You can.

Furthermore, in the present invention, the first wiper or the second wiper is supported by a rotatable support member,
The maintenance liquid applying means is a maintenance liquid storage tank that stores the maintenance liquid,
The support member is connected to the maintenance liquid storage tank,
The inkjet head cleaning device is characterized in that the first wiper or the second wiper is immersed in the maintenance liquid stored in the maintenance liquid storage tank by rotating the support member. You can.

Furthermore, in the present invention, the first wiper or the second wiper is a rotatable rod-shaped shaft having an outer peripheral surface,
a first position on the circumferential surface of the rod-shaped shaft and a second position spaced apart from the predetermined position by a predetermined distance with respect to the rotating direction of the rod-shaped shaft in a transverse direction intersecting the direction of the relative movement; A plurality of the first wipers for wiping the nozzle surfaces of each of the plurality of inkjet heads arranged at intervals are arranged in the axial direction of the rod-shaped shaft at intervals corresponding to the first intervals,
Further, at each of a third position on the circumferential surface of the rod-shaped shaft and a fourth position spaced apart from the third position by a predetermined distance with respect to the rotating direction of the rod-shaped shaft, arranged at the first interval in the intersecting direction. a plurality of the second wipers for wiping the nozzle surface of each of the plurality of inkjet heads, which are arranged in the axial direction of the rod-shaped shaft at intervals corresponding to the first interval;
The nozzle surfaces of the plurality of inkjet heads whose nozzle surfaces are wiped by the plurality of first wipers arranged at the first position are wiped by the plurality of second wipers arranged at the third position. , the nozzle surfaces of the plurality of inkjet heads whose nozzle surfaces are wiped by the plurality of first wipers arranged at the second position are wiped by the plurality of second wipers arranged at the fourth position; Wipe off,
In a plurality of inkjet heads, the nozzle surfaces of which are wiped by the plurality of first wipers arranged at the second position, the nozzle surfaces are wiped by the plurality of first wipers arranged at the first position. The inkjet head cleaning device may be configured to be arranged at a second interval in the direction of the relative movement with respect to the plurality of inkjet heads being taken.

In the present invention, the above-mentioned structure solves the above problems, and the inkjet head can maintain normal ejection of ink by reliably removing contamination such as ink mist generated on the nozzle surface of the inkjet head. A head cleaning method and an inkjet head cleaning device could be provided.

1 is a schematic front view of an inkjet drawing device that is an embodiment of the present invention. 1 is a schematic plan view of an inkjet drawing device that is an embodiment of the present invention. 1 is a schematic cross-sectional view of a cleaning unit that is an embodiment of the present invention. 1 is a sectional view of a water-retaining wiper and a blade wiper according to an embodiment of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a front view of a water-retaining wiper and a blade wiper according to an embodiment of the present invention. 1 is a flowchart showing a cleaning sequence for an inkjet head according to an embodiment of the present invention. FIG. 3 is a schematic diagram showing a contamination state of an inkjet head. FIG. 2 is a bottom view of a carriage on which a plurality of inkjet heads are mounted according to an embodiment of the present invention, on the side of an inkjet head nozzle surface. FIG. 1 is a perspective view of a wiper unit that constitutes a cleaning unit that is an embodiment of the present invention. FIG. 1 is a side view of a wiper unit that constitutes a cleaning unit that is an embodiment of the present invention. FIG. 1 is a front view of a wiper unit that constitutes a cleaning unit that is an embodiment of the present invention. FIG. 1 is a block diagram showing the electrical configuration of an inkjet drawing device that is an embodiment of the present invention. 1 is a block diagram showing an electrical configuration regarding an ink supply path in an inkjet drawing apparatus that is an embodiment of the present invention. FIG.

Embodiments of the present invention will be described in detail below with reference to the drawings.

First, as an embodiment of the present invention, an inkjet drawing apparatus equipped with a cleaning unit will be described with reference to FIGS. 1 and 2.

FIG. 1 is a front view of an inkjet drawing apparatus that is an embodiment of the present invention, and FIG. 2 is a plan view of the inkjet drawing apparatus that is an embodiment of the invention.

The inkjet drawing apparatus 1 in this embodiment includes a carriage 13 on which a plurality of inkjet heads 11 are mounted. The inkjet head 11 has a nozzle surface on which a plurality of nozzles for ejecting ink are arranged, and in this embodiment, the nozzle surface has a rectangular shape. These multiple nozzles are arranged side by side in the longitudinal direction (X-axis direction) of the nozzle surface.

Further, in this embodiment, as shown in FIG. 2, a plurality of inkjet heads 11 are arranged on the carriage 13 in parallel to the X-axis direction and in the Y-axis direction.

The carriage 13 is connected to an X-axis moving means 15 for moving the carriage 13 substantially horizontally.
The X-axis moving means moves the carriage 13 above the platen on which the recording medium is placed during printing, and moves the carriage 13 away from above the platen and above the cleaning unit 3 when not printing and when cleaning the inkjet head 11. move it. In this embodiment, the X-axis moving means 15 is arranged to move in a direction (X-axis direction) that is substantially perpendicular to the recording medium conveyance direction (Y-axis direction).
Note that it is preferable to use a linear motor, which is a drive system for linear movement, as the X-axis moving means, and an appropriate one such as a linear motor, a ball screw, or a timing belt is used. In this embodiment, a linear motor is used.

Further, the carriage 13 is connected to a Z-axis moving means 17 for moving the carriage 13 in the vertical direction (Z-axis direction).
A servo motor, a stepping motor, etc. are used as the Z-axis moving means. In this embodiment, a servo motor is used. Note that it is preferable that the Z-axis moving means is equipped with a brake means to prevent it from falling.

The cleaning unit 3 is disposed at a position where the carriage 13 passes by the X-axis moving means 15 and at a position below the carriage 13.

The cleaning unit 3 includes a wiper unit 7, which includes a blade wiper 21 and a water-retentive wiper 23 connected to a rod-shaped shaft 19. The wiper unit 7 is rotatably connected to a maintenance liquid storage tank in which maintenance liquid is stored. 26.

Further, an ink purge tray 27 is connected adjacent to the maintenance liquid storage tank for receiving ink forcibly discharged from the nozzles of the inkjet head 11 when an ink purge, which will be described later, is performed.

When executing the cleaning sequence, the cleaning unit 3 moves the carriage 13 to a cleaning position above the cleaning unit 3 by driving the X-axis moving means 15 to execute the cleaning sequence.
In addition, a capping unit 5 for storing the inkjet head 11 by blocking the nozzle surface of the inkjet head 11 from outside air when not printing and preventing ink from drying is adjacent to the cleaning unit 3 and is movable approximately horizontally in the Y-axis direction. is connected to the Y-axis moving means 29, and is arranged above the cleaning unit 3 (in the Z-axis direction).

During capping, the capping unit 5 moves to above the cleaning unit 3. On the other hand, after the carriage 13 moves above the capping unit 5, it is lowered by the shaft moving means 17. Thereby, the nozzle surface of the inkjet head 11 is connected to the capping rubber 31 constituting the capping unit 5 and capped.
During printing and when performing a cleaning sequence, the capping unit 5 is horizontally moved and retracted from above the cleaning unit 3.
As with the X-axis moving means, a direct-acting motor is used for the Y-axis moving means, and an appropriate one such as a linear motor, a ball screw, or a timing belt is used.

Next, the electrical configuration of the inkjet drawing apparatus 1 according to this embodiment will be described with reference to FIGS. 12 and 13.

FIG. 12 is a block diagram showing the electrical configuration of the inkjet drawing apparatus 1.
The inkjet drawing apparatus 1 in this embodiment includes a control computer 41. The control computer 41 includes, for example, a CPU and a memory.

The memory is composed of, for example, RAM and ROM, and the CPU's calculation results and print image data are temporarily recorded in the RAM. The ROM also contains a cleaning sequence execution program as shown in the flowchart shown in FIG. 6, as well as a control program for driving and controlling the inkjet head 11 and the various moving means of the X, Y, and Z axes described above. Stored.

The control computer 41 is connected to and communicates with the controller 43 via an interface such as a LAN. For example, a programmable controller (PLC) is used as the controller 43, and controls various connected drivers.

The controller 43 drives and controls the linear motor 53 that constitutes the X-axis moving means 15 via the motor drive driver 45, and drives the drive motor 55 that constitutes the Z-axis moving means via the motor drive driver 47. It's in control. Further, via a motor drive driver 49, a drive motor 51 that rotates a rod-shaped shaft 19, which will be described later, is drive-controlled.

FIG. 13 is a block diagram showing an electrical configuration for controlling the inkjet head and ink supply system in the inkjet drawing apparatus 1.
Similar to FIG. 12, the inkjet head 11 and the ink supply system are controlled by a control computer 41 and a controller 43.
The controller 43 is connected via a motor control driver 62 to a motor 65 that drives the tube pump.
In response to a command from the controller 43, a motor 65 is driven, and ink is supplied from an ink tank 61 storing ink via a tube 63 to a sub-tank 67 that adjusts the air pressure in the ink path. More specifically, the sub-tank 67 is equipped with a liquid level sensor, and the controller 43 drives the motor 65 based on a signal from the liquid level sensor connected to the sub-tank 67, so that a set amount of ink is supplied into the sub-tank 67. It is controlled as follows.

An air valve 69 is connected to the sub-tank 67, and the open/close state of the air valve 69 is controlled by a controller 43 that receives instructions from a control computer 41.
The atmospheric pressure in the sub-tank 67 is controlled by switching the open/close state of the air valve 69 to change the supply relationship of positive pressure or negative pressure from the positive pressure supply source 71 and the negative pressure supply source 73 connected to the air valve 69. ing.

More specifically, under normal conditions, the pressure inside the sub-tank is maintained at a negative pressure to prevent ink from leaking from the nozzles of the inkjet head 11. When performing an ink purge, which will be described later, by switching the pressure inside the sub-tank 69 to positive pressure using the above control, the ink supplied into the sub-tank 69 is pushed out from the nozzle of the inkjet head 11 by the positive pressure, and the ink is pushed out from the nozzle. Forced to be ejected. Furthermore, by controlling the time during which positive pressure is applied, the amount of ink forced to be discharged by ink purge can be adjusted.

Next, the cleaning unit 3 according to the embodiment of the present invention will be described in detail with reference to FIGS. 1 to 5 as appropriate.

FIG. 3 is a schematic cross-sectional view of the cleaning unit 3 according to the embodiment of the present invention.

The cleaning unit 3 includes a wiper unit 7, a maintenance liquid storage tank 26 in which maintenance liquid is stored, and an ink purge tray 27.

The wiper unit 7 has a first wiper and a second wiper mounted on a rod-shaped shaft 19 such that the first wiper and the second wiper are arranged radially with respect to the axial center of the rod-shaped shaft 19 and one rectangular end is approximately parallel to the axial direction of the rod-shaped shaft 19. is supported by In this embodiment, a rectangular water-retaining wiper 23 is used as the first wiper, and a rectangular blade wiper 21 is used as the second wiper. Hereinafter, as a description of this embodiment, the first wiper will be described as the water-retaining wiper 23, and the second wiper will be described as the blade wiper 21.

The cross-sectional shape of the rod-shaped shaft 19 is designed so that when the water-retaining wiper 23 or the blade wiper 21 contacts the nozzle surface of the ink-jet head 11, the water-retaining wiper 23 or the blade wiper 21 can wipe the nozzle surface of the ink-jet head 11 uniformly during the cleaning sequence. The distance between the outer peripheral point of the rod-shaped shaft 19, where the blade wiper 23 or the blade wiper 21 and the rod-shaped shaft 19 are connected, and the nozzle surface of the inkjet head 11 in a direction substantially perpendicular to the nozzle surface is configured to be uniform. It is preferable that the For example, a cylindrical shape, a regular polygonal shape, etc. are assumed. In this embodiment, the shape is a regular polygon, which is a regular hexagon.
A drive motor 51 is connected to an end of the rod-shaped shaft 19 for rotating the rod-shaped shaft 19 and the water-retentive wiper 23 and blade wiper 21 connected thereto about the axis of the rod-shaped shaft 19. There is. As described above, the drive motor 51 rotates the rod-shaped shaft 19 via the motor drive driver 49 under the control of the controller 43.

By controlling the drive motor 51, when performing a cleaning sequence, the rod-shaped shaft 19 is rotated to bring the water-retaining wiper 23 and the blade wiper 21 into contact with the nozzle surface of the inkjet head 11, and the water-retaining wiper 23 and the blade wiper are 21 can be immersed in the maintenance liquid stored in the maintenance liquid storage tank 26 for cleaning.

The drive motor 51 is preferably operable to stop the water retaining wiper 23 and the blade wiper 21 at a position where they come into contact with the nozzle surface of the inkjet head 11, and a servo motor, a stepping motor, or the like is suitable.
Note that in this embodiment, a configuration is shown in which both the water-retentive wiper 23 and the blade wiper 21 are connected to one rod-shaped shaft 19, but if the configuration includes both the water-retentive wiper and the blade wiper, It is confirmed that a configuration in which multiple rod-shaped shafts are connected separately or other configurations are also possible.

Here, the structures of the water retaining wiper 23 and the blade wiper 21 will be explained.
4 is a sectional view of the water-retaining wiper 23 and the blade wiper 21, and FIG. 5 is a front view of the water-retaining wiper 23 and the blade wiper 21.
In this embodiment, as shown in FIG. 5, both the water retaining wiper 23 and the blade wiper 21 are formed into a thin rectangular shape. It is effective for each wiper to have a shape that covers the width direction (width direction) of the nozzle surface of the inkjet head 11 so that ink on the nozzle surface can be reliably removed.

As described later, the material of the water-retentive wiper 23 needs to be a material that has water-retentive properties that can retain the liquid in order to wipe the nozzle surface of the inkjet head 11 while absorbing and retaining the maintenance liquid. .
Therefore, a porous material having a high water retention rate and containing a continuous pore structure is suitable. For example, it may be constructed of a sponge-like open foam such as urethane, polystyrene, polypropylene, or polyethylene, woven fabric, nonwoven fabric, or a combination thereof.

The material of the blade wiper 23 is preferably an elastic material that does not damage the nozzle surface when it comes into contact with the nozzle surface and can follow the nozzle surface, and since it is immersed in ink, it should have chemical resistance. It is preferable that the material is chemically stable. For example, silicone rubber (Si, Q), ethylene propylene rubber (EPM), ethylene propylene diene rubber (EPDM), fluororubber (FKM), etc. are assumed.

A maintenance liquid storage tank 26 in which maintenance liquid is stored is provided at the bottom of the wiper unit 7, and when the wiper unit 7 is rotated, the water-retentive wiper 23 or the blade wiper 21 is immersed in the stored maintenance liquid. It is located so that it can be washed easily.

The maintenance liquid used in the maintenance unit is appropriately selected and used depending on the type and characteristics of the ink used in the inkjet drawing apparatus 1, and is capable of dissolving and cleaning the ink.

Next, an inkjet head cleaning sequence according to an embodiment of the present invention will be described.

The cleaning sequence is executed as appropriate, for example, when the inkjet drawing apparatus 1 is started, before printing starts, and before capping the inkjet head after printing ends.

FIG. 6 is a flowchart illustrating the cleaning sequence. The cleaning sequence will be described below with reference to FIG. 6.

First, before performing the first wiping step, a water-retentive wiper cleaning step of flow 2 is performed. This is to keep the water-retentive wiper 23 clean and prevent impurities from adhering to the nozzle surface of the inkjet head 11 before executing the first wiping step. The purpose is to supply and apply it to the water-retaining wiper 23. Note that other methods can be envisaged as means for applying the maintenance liquid to the water-retaining wiper 23, such as a method of providing a supply path for supplying the maintenance liquid inside the water-retaining wiper 23.

In this embodiment, the control computer 41 issues a command to the drive motor 51 connected to the wiper unit 7 via the controller 43 and the motor drive driver 49 to rotate the wiper unit 7. Then, the water-retaining wiper 23 connected to the rod-shaped shaft 19 constituting the wiper unit 7 is immersed in the maintenance liquid stored in the maintenance liquid storage tank to execute the water-retaining wiper cleaning step.

Next, a first wiping step is performed. The configuration of the first wiping step will be explained.

First, in order to wipe the nozzle surface with the water-retaining wiper 23, a water-retaining wiper standby step shown in flow 2 is performed in which the water-retaining wiper 23 is arranged to face and be substantially orthogonal to the nozzle surface.

In this embodiment, the control computer 41 issues a command to the drive motor 51 connected to the wiper unit 7 via the controller 43 and the motor drive driver 49 to rotate the wiper unit 7 and move the water-retentive wiper 23 approximately vertically. Place it in

Next, water-retaining wiper wiping in flow 3 is performed, in which the water-retaining wiper 23 is brought into contact with the nozzle surface, and the water-retaining wiper 23 and the inkjet head 11 are moved relative to each other to wipe the nozzle surface.

In this embodiment, a command is issued from the control computer 41 to the controller 43 to drive the direct-acting motor 53 via the motor drive driver 45 to drive the X-axis moving means 15, thereby driving the inkjet head 11 mounted on the carriage 13. is moved above the water-retaining wiper 23, which is arranged substantially vertically facing the nozzle surface.

Next, the control computer 41 issues a command to the controller 43 to drive the drive motor 55 via the motor drive driver 47 to drive the Z-axis moving means 17 to move the inkjet head 11 mounted on the carriage 13 along the Z-axis. the nozzle surface and the tip of the water-retentive wiper 23 are brought into contact with each other. At this time, if the inkjet head 11 is moved so that the water-retentive wiper 23 comes into contact with one end of the nozzle surface in the longitudinal direction (X-axis direction), more efficient wiping can be achieved.

Then, the X-axis moving means is driven in the same manner as described above, and the inkjet head 11 mounted on the carriage 13 is moved approximately in parallel while maintaining the state in which the nozzle surface and the tip of the water-retentive wiper 23 are in contact with each other. and execute flow 3.

In this way, the purpose of performing wiping with the water-retaining wiper 23 before wiping with the blade wiper 21, which will be described later, is to immerse the nozzle surface with the maintenance liquid held by the water-retaining wiper, thereby cleaning the inkjet head during printing, etc. This is to reduce the viscosity of the ink that has adhered to the nozzle surface of No. 11, dried, and increased in viscosity with the cleaning liquid so that it can be easily wiped off from the nozzle surface.

In other words, when ink mist generated during inkjet printing adheres to the nozzle surface, especially when using water-based ink that tends to dry and thicken, the viscosity increases due to evaporation of the solvent, as shown in Figure 7α. The sticky ink 33 will accumulate on the nozzle surface. When trying to wipe off the thickened ink adhering to the nozzle surface with a wiper made of an elastic material such as rubber, the thickened ink 33 exhibits adhesion to the nozzle surface, resulting in the thickened ink being removed by the wiper. cannot be removed, and the thickened ink 33 is instead spread out on the nozzle surface, as shown in FIG. 7β. As a result, the thickened ink causes nozzle clogging, and in the worst case, the inkjet head 11 is damaged. Furthermore, it may be difficult to sufficiently remove thickened ink even with an ink purge described below, and incomplete removal of thickened ink may cause nozzle clogging.

Therefore, it is effective to reduce the viscosity of the adhered ink, so in this embodiment, by performing wiping with the water-retentive wiper 23 that holds the maintenance liquid, the viscosity of the thickened ink 33 is lowered and dissolved by the maintenance liquid. While doing so, wiping is performed to remove the thickened ink 33.

Note that in the first wiping step, if a plurality of inkjet heads 11 are mounted on the carriage 13, Flow 2 and Flow 3 are repeatedly executed according to the flowchart of FIG. 6. A specific method of repeating the first wiping step when a plurality of inkjet heads 11 are mounted on the carriage 13 will be described later.
As described above, the first wiping step is completed by repeating Flow 2 and Flow 3 as necessary according to the flow of FIG.

Next, the ink purge step of flow 4 will be explained.
In flow 4, ink is forcibly discharged (ink purge) from the plurality of nozzles forming the nozzle surface of the inkjet head 11, and the insides of the nozzles are cleaned.

As the ink purging method, a method of forcibly supplying ink to the nozzle, a method of suctioning ink from the nozzle with air, and other appropriate methods can be assumed.

In this embodiment, the carriage 13 is moved in the X-axis direction, the carriage 13 is evacuated from above the maintenance liquid storage tank 26, and moved onto the ink purge tray 27, which is the ink purge position. Then, as described above, the control computer 41 issues a command to the air valve 69 via the controller 43 to switch the pressure in the sub-tank 69 to positive pressure. 11. As a result, ink is forcibly discharged from the nozzles of the inkjet head 11.

Further, depending on the usage status of the inkjet head 11, the amount of ink forced to be ejected by ink purging is adjusted by controlling the time during which positive pressure is applied. Furthermore, by retracting the inkjet head 11 onto the ink purge tray 27 and performing ink purging, the ink discharged into the maintenance liquid storage tank 26 can enter and unnecessarily contaminate the stored maintenance liquid. Avoid.

Here, the purpose of performing the ink purge step after the first wiping step will be explained.

In the first wiping step, when the nozzle surface is moistened with a large amount of cleaning liquid and wiping is performed using the water-retaining wiper 23, the cleaning liquid is absorbed by capillary action because the diameter of the nozzle (orifice) that makes up the nozzle surface is very small. The maintenance liquid enters the nozzle and mixes with the ink near the nozzle.

In inkjet printing, for stable ink ejection, it is necessary to control the ink meniscus (the curved surface formed on the surface of the ink in the nozzle due to the interfacial tension of the ink) in the nozzle portion of the inkjet head 11 into an appropriate shape. . However, when the maintenance liquid mixes into the ink in the nozzle, the interfacial tension characteristics of the ink in the nozzle change, making it impossible to maintain a predetermined meniscus shape, resulting in the meniscus being destroyed. Therefore, if printing is continued as it is, ink ejection abnormalities will occur and print image quality will deteriorate.

In order to prevent this problem using only a water-retaining wiper such as a sponge or non-woven fabric and to complete the cleaning of the inkjet head 11 with only the first wiping step, the amount of maintenance liquid held by the water-retaining wiper is controlled. There is a need. However, in order to do this, it is necessary to introduce a mechanism that squeezes the water-retaining wiper to maintain a predetermined amount of maintenance liquid, or to control the amount of squeezing. is required. In order to realize such a method, difficult control is required, and the mechanical configuration of the cleaning unit and the inkjet drawing apparatus 1 as a whole becomes extremely complicated and expensive.

Therefore, in the present embodiment, by performing an ink purge step after the first wiping step, not only the fine impurities mixed in the nozzles of the inkjet head 11 are discharged, but also the ink mixed with the cleaning liquid is removed. can be drained and the proper ink meniscus shape restored.

Immediately after the ink purge step of flow 4 is completed, or while flow 4 is being executed, the blade wiper cleaning step of flow 5 is performed. The purpose of this is to keep the blade wiper 21 clean and prevent impurities from adhering to the nozzle surface of the inkjet head 11 before performing the second wiping step.

In this embodiment, the wiper unit 7 is rotated to immerse the blade wiper 21 in the maintenance liquid stored in the maintenance liquid storage tank 26.

Immediately after flow 4 and flow 5 are completed, the second wiping step is performed. The configuration of the second wiping step will be explained.

First, in flow 6, a blade wiper standby step is performed in which the blade wiper 21 is arranged to face and be substantially perpendicular to the nozzle surface so that the blade wiper 21 can wipe the nozzle surface. In this embodiment, the wiper unit 21 is rotated and the blade wiper 21 is disposed approximately vertically upward.

Next, in Flow 7, wiping with the blade wiper is performed in which the blade wiper 21 is brought into contact with the nozzle surface, and the blade wiper 21 and the inkjet head 11 are moved relative to each other to wipe the nozzle surface.

In this embodiment, a command is issued from the control computer 41 to the controller 43 to drive the direct-acting motor 53 via the motor drive driver 45 to drive the X-axis moving means 15, thereby driving the inkjet head 11 mounted on the carriage 13. is moved above the blade wiper 21, which is arranged substantially vertically facing the nozzle surface.
Next, the control computer 41 issues a command to the controller 43 to drive the drive motor 55 via the motor drive driver 47 to drive the Z-axis moving means 17 to move the inkjet head 11 mounted on the carriage 13 along the Z-axis. The nozzle surface and the tip of the blade wiper 21 are brought into contact with each other. At this time, if the inkjet head 11 is moved so that the blade wiper 21 comes into contact with one end of the nozzle surface in the longitudinal direction (X-axis direction), more efficient wiping can be achieved.
Then, the X-axis moving means is driven in the same manner as described above, and the inkjet head 11 mounted on the carriage 13 is moved approximately in parallel while maintaining the state in which the nozzle surface and the tip of the blade wiper 21 are in contact with each other. , execute flow 7.

In flow 7, the ink discharged from the nozzle in the ink purge step of flow 4 and attached to the nozzle surface is wiped and removed.

Note that at this stage, since the time from execution of flow 4 to execution of flow 7 is short, the ink adhering to the nozzle surface has not yet dried and thickened, and the ink can be completely removed. Further, in this embodiment, the blade wiper 21 is formed of an elastic body that does not have water retention properties. Therefore, there is a possibility that some maintenance liquid may have adhered to the cleaning liquid due to flow 5, but since the nozzle does not hold cleaning liquid that would mix with the cleaning liquid due to capillary action, the ink meniscus may be destroyed due to mixing of the cleaning liquid. does not occur either.

In addition, if a plurality of inkjet heads 11 are mounted on the carriage 13, repeat steps 6 and 7 in the same way as in the first wiping step to wipe all the inkjet heads mounted on the carriage 13. Wipe the nozzle surface of the head 11.

By executing the above flow, the second wiping step is completed, and the entire cleaning sequence according to this embodiment is completed.

After all cleaning sequences are completed, if necessary, move the carriage 13 onto the platen on which the recording medium is placed to start printing, or to end printing, as necessary. , the capping unit 5 is moved onto the cleaning unit 3, the carriage 13 is lowered in the Z-axis direction, and the nozzles of the inkjet head 11 are brought into contact with the capping portion of the capping unit 5 to complete capping.

Furthermore, as another embodiment, a method of performing the first wiping step and the second wiping step when inkjet heads are arranged in a plurality of rows on a carriage will be described.

In an inkjet printer, when it is necessary to print a wide width at once, a plurality of inkjet heads are arranged in a predetermined row in the direction of the nozzle row, and the nozzles of each inkjet head 11 are overlapped so that the nozzle rows of each inkjet head 11 overlap. Generally, a method is used in which the device is placed on a carriage.

An appropriate arrangement method for arranging the inkjet heads in an overlapping manner is assumed depending on the shape of the inkjet head, but as an example, in the case of the inkjet head 11 in this embodiment in which the nozzle surface is formed in a rectangular shape, As shown in FIG. 8, a plurality of inkjet heads 11 are arranged adjacently on a straight line at intervals in the longitudinal direction (nozzle row direction), and further inkjet heads 11 are arranged. The nozzle arrays are arranged parallel to the direction of the nozzle rows and in open spaces so that the ends of the nozzle rows forming the nozzle surfaces of all the inkjet heads 11 overlap each other.

Such an overlapping arrangement of the inkjet heads 11 means that, for example, when the recording medium passes once under the nozzle surface of the inkjet heads 11, all the ink necessary for image formation is applied and printing is completed. It is applied in the case of a so-called one-pass method in which printing is performed in a single scan, or in cases where it is necessary to improve production takt time by widening the printable width with a single scan.

In this case, when wiping is performed from one end of the nozzle surface in the nozzle row direction toward the other end, if the nozzle surfaces of all the arranged inkjet heads 11 are wiped at once, Since the nozzle surfaces of the inkjet heads 11 are not connected to each other and are spaced apart from each other, not only the nozzle surfaces but also the bottom surface of the carriage 13 on the nozzle surface side are wiped at the same time.

If the bottom surface of the carriage 13 is wiped in this way, there may be problems such as spreading impurities adhering to the bottom surface of the carriage 13 onto the nozzle surface of the inkjet head 11 or creating a gap between the bottom surface of the carriage 13 and the nozzle surface of the inkjet head 11. There also arises a problem that the wiper may come into contact with the wiper and damage the wiper.

Therefore, a configuration for avoiding these problems will be explained.

First, among the plurality of inkjet heads 11 to be wiped, inkjet heads 11 that can be wiped at one time are set as one inkjet head group according to the arrangement of the inkjet heads 11.

Regarding the setting method of such an inkjet head group, if the inkjet head 11 has a rectangular nozzle surface as shown in FIG. A plurality of inkjet heads 11 arranged at predetermined intervals in the direction of the inkjet head are set as one inkjet head group. In the example of this embodiment, the inkjet head 11 is arranged substantially parallel to the longitudinal direction of the inkjet head 11, and one longitudinal end of the inkjet head 11 is arranged substantially perpendicular to the longitudinal direction of the inkjet head 11. A plurality of inkjet heads 11 are set as one inkjet head group.

In the example of FIG. 8, two inkjet heads 11 indicated by α and two inkjet heads 11 indicated by β each form one inkjet head group. Further, the inkjet heads 11 constituting the inkjet head group α are spaced at a predetermined interval in the X-axis direction, which is the direction in which the inkjet heads 11 are moved by the X-axis moving means 15, and in the Y-axis direction, which intersects this. The two arranged inkjet heads 11 designated as γ form one inkjet head group. Here, they will be described as an inkjet head group α, an inkjet head group β, and an inkjet head group γ, respectively.

Next, the structure of the wiper unit 7 when wiping is performed on a plurality of inkjet head groups will be described in detail with reference to FIGS. 9 to 11.

As shown in FIGS. 9 and 10, the cross-sectional shape of the rod-shaped shaft 19 is a regular polygon, and in this embodiment, it is a regular hexagon. Each time the number of rows of inkjet heads 11 to be wiped increases, or each time the number of inkjet head groups increases, it is possible to assume a further polygonal shape or a circular shape.

As shown in FIGS. 9 and 11, a plurality of water-retentive wipers 23 for realizing the first wiping step are arranged on a surface of the rod-shaped shaft 19 that forms one side of a regular hexagon on the outer peripheral surface of the rod-shaped shaft 19. They are arranged in a line according to the spacing between them. With the arrangement of the inkjet heads 11 shown in FIG. 8, the water-retaining wiper 23 is also arranged at a predetermined interval between the two inkjet heads 11, indicated by α. The plurality of water-retaining wipers 23 arranged in a line in this manner are considered to be one water-retaining wiper group, and will be referred to as water-retaining wiper group A here.

Further, as shown in FIGS. 9 to 11, a plurality of water-retaining wipers 23 are arranged around the outer circumference of the rod-shaped shaft 19, which is offset from the outer peripheral surface on which the water-retaining wiper group was previously arranged with respect to the center of the rotation axis of the rod-shaped shaft 19. The water-retentive wiper 23 placed earlier is placed on the other surface constituting one side of the regular hexagon, with the position shifted in the axial direction of the rod-shaped shaft 19. With the arrangement of the inkjet heads 11 shown in FIG. 8, the water-retentive wiper 23 is also arranged in accordance with the interval between the two inkjet heads 11, which is indicated by γ. The plurality of water-retaining wipers 23 arranged in a row in this manner are referred to as another water-retaining wiper group, and here, water-retaining wiper group B. Each time the number of rows of inkjet heads 11 to be wiped increases, and each time the number of inkjet head groups increases, the number of water-retentive wiper groups C and D and the number of water-retentive wiper groups are similarly increased.

In addition, similar to the arrangement of the water-retaining wiper 23, as shown in FIGS. 9 and 11, a plurality of blade wipers 21 for realizing the second wiping step are arranged in a manner similar to the arrangement of the water-retaining wiper group A and the water-retaining wiper group B, as shown in FIGS. The inkjet heads 11 are arranged at predetermined intervals on a surface constituting the other regular hexagonal side of the outer peripheral surface of the rod-shaped shaft 19 whose circumference is shifted from the arranged outer peripheral surface with respect to the center of the rotation axis of the rod-shaped shaft 19. arranged in a row. With the arrangement of the inkjet heads 11 shown in FIG. 8, the blade wiper 21 is also arranged in accordance with the interval between the two inkjet heads 11 indicated by α. The plurality of blade wipers 21 arranged in a line in this manner are referred to as one blade wiper group, and will be referred to as blade wiper group A here.

Furthermore, as shown in FIGS. 9 to 11, a plurality of blade wiper groups are arranged in a rod-like shape whose circumference is shifted from the outer circumferential surface on which the water-retentive wiper group and the blade wiper group have been arranged with respect to the rotational axis center of the rod-shaped shaft 19. The blade wiper 21 placed earlier is placed on a surface constituting one side of the other regular hexagon on the outer peripheral surface of the shaft 19, with the blade wiper 21 being shifted in position in the axial direction of the rod-shaped shaft 19. With the arrangement of the inkjet heads 11 shown in FIG. 8, the blade wiper 21 is also arranged in accordance with the interval between the two inkjet heads 11, which is indicated by γ. The plurality of blade wipers 21 arranged in a line in this manner are referred to as another blade wiper group, and herein are referred to as blade wiper group B. Each time the number of rows of inkjet heads 11 to be wiped increases, and each time the number of inkjet head groups increases, the number of water-retentive wiper groups C and D and the number of water-retentive wiper groups are increased in the same way.

The wiper unit 7 is configured as described above. Note that the wiper unit 7 does not necessarily have to be composed of only one rod-shaped shaft 19, and if necessary, each wiper group may be appropriately divided and arranged using a plurality of rod-shaped shafts 19, and the wiper unit 7 does not rotate. Confirm that it is okay to use this method.

Next, a method of implementing the first wiping step and the second wiping step in this embodiment will be explained.

First, a case where the first wiping step is performed on a plurality of inkjet heads 11 arranged as shown in FIG. 8 will be described. First, a first wiping step is performed on the inkjet head group α using the water-retentive wiper group A.
Next, a second first wiping step is performed on the inkjet head group α and the inkjet head group β that are lined up in the longitudinal direction of the nozzle surface of the inkjet head 11 using the water-retentive wiper group A.

Then, the wiper unit 7 is rotated, and the first wiping step is performed for the third time on the inkjet head group γ using the water-retentive wiper group B.
Through the above process, the first wiping step could be performed on all inkjet heads 11.

Also, a case will be described in which the second wiping step is performed on a plurality of inkjet heads 11 arranged as shown in FIG. 8. First, the first second wiping step is performed on the inkjet head group α using the blade wiper group A.
Next, a second wiping step is performed for the second time using the blade wiper group A on the inkjet head group α and the inkjet head group β that are lined up in the longitudinal direction of the nozzle surface of the inkjet head 11.

Then, the wiper unit 7 is rotated, and the second wiping step is performed for the third time on the inkjet head group γ using the blade wiper group B.
Through the above process, the second wiping step could be performed on all inkjet heads 11.

The reason for the above configuration will be explained below by taking the first wiping step as an example.

For example, in the example of FIG. 8, a plurality of water-retaining wipers 23 are placed on one side of the regular hexagon on the outer peripheral surface of the rod-shaped shaft 19, and the water-retaining wipers 23 are placed on the inkjet head group α and the inkjet head group α. Arrange four sheets according to the spacing of γ. However, when performing the first wiping step with such a configuration, when wiping is started from one end in the longitudinal direction of the nozzle surface of the inkjet head 11, when wiping the inkjet head group α, the inkjet head group α and Since the starting point of wiping is different for the inkjet head group γ, wiping ends up reaching the bottom surface of the carriage 13 in the nozzle row direction of the inkjet head group γ. In this process, a problem arises in that the bottom surface of the carriage 13 is wiped.

Therefore, by arranging water-retaining wiper group A and water-retaining wiper group B separately as described above, when wiping inkjet head group α or inkjet head group β, water retention for wiping inkjet head group γ is possible. Since the wiper group B does not wipe the bottom surface of the carriage 13, the above problem can be avoided. The same applies to the second wiping step.

With the above configuration, even when a plurality of inkjet heads 11 were used, the cleaning sequence could be appropriately performed.

1 Inkjet drawing device 3 Cleaning unit 5 Capping unit 7 Wiper unit 11 Inkjet head 13 Carriage 15 Moving means 33 Thickened ink 41 Control computer 43 Controller 45 Motor drive driver 47 Motor drive driver 49 Motor drive driver 51 Drive motor 53 Direct motor 55 Drive motor 61 Ink tank 62 Motor drive driver 63 Ink supply path 65 Motor 67 Sub tank 69 Air Valve 71 Positive pressure supply source 73 Negative pressure supply source

Claims (19)

In a method for cleaning an inkjet head having a nozzle surface on which a plurality of nozzles for ejecting ink are arranged,
a first wiping step of wiping the nozzle surface by relative movement between the first wiper and the inkjet head with a maintenance liquid applied to the first wiper;
After performing the first wiping step, an ink purge step of performing a discharge operation to forcibly discharge ink from the plurality of nozzles;
a second wiper cleaning step of performing a second wiper cleaning operation of cleaning the second wiper with the maintenance liquid during or after the discharge operation;
a second wiping step of wiping the nozzle surface by relative movement of the second wiper cleaned by the second wiper cleaning operation and the inkjet head after performing the discharge operation in the ink purging step;
A method for cleaning an inkjet head having: In a method for cleaning a plurality of inkjet heads having a nozzle surface on which a plurality of nozzles for ejecting ink are arranged,
a first wiping step of wiping the nozzle surface by relative movement between the first wiper and the inkjet head with a maintenance liquid applied to the first wiper;
After performing the first wiping step, an ink purge step of performing a discharge operation to forcibly discharge ink from the plurality of nozzles;
a second wiping step of wiping the nozzle surface by relative movement of a second wiper and the inkjet head after performing the ejection operation in the ink purging step ;
In the first wiping step, the inkjet head performs relative movement between the first wiper and the inkjet head a plurality of times, and wipes the nozzle surface of a different inkjet head among the plurality of inkjet heads in each relative movement. cleaning method. In a method for cleaning a plurality of inkjet heads having a nozzle surface on which a plurality of nozzles for ejecting ink are arranged,
a first wiping step of wiping the nozzle surface by relative movement between the first wiper and the inkjet head with a maintenance liquid applied to the first wiper;
After performing the first wiping step, an ink purge step of performing a discharge operation to forcibly discharge ink from the plurality of nozzles;
a second wiping step of wiping the nozzle surface by relative movement of a second wiper and the inkjet head after performing the ejection operation in the ink purging step ;
In the second wiping step, the inkjet head performs relative movement between the second wiper and the inkjet head a plurality of times, and wipes the nozzle surface of a different inkjet head among the plurality of inkjet heads in each relative movement. cleaning method. The first wiping step includes arranging the first wiper to face the nozzle surface, moving the inkjet head to a wiping start position where the nozzle surface and the first wiper are in contact with each other, and The step includes a step of relatively moving the inkjet head and the first wiper while the nozzle surface and the first wiper are in contact with each other,
The second wiping step includes arranging the second wiper to face the nozzle surface, moving the inkjet head to a wiping start position where the nozzle surface and the second wiper are in contact with each other, and The inkjet head according to any one of claims 1 to 3, comprising a step of relatively moving the inkjet head and the second wiper while the nozzle surface and the second wiper are in contact with each other. Cleaning method. Before performing the first wiping step, performing a first wiper cleaning step of cleaning the first wiper with the maintenance liquid,
The inkjet head cleaning according to any one of claims 1 to 4 , wherein a second wiper cleaning step of cleaning the second wiper with the maintenance liquid is performed before performing the second wiping step. Method. Wiping the nozzle surface of the first inkjet head by one of the plurality of relative movements between the first wiper and the inkjet head, and the plurality of relative movements between the first wiper and the inkjet head. The nozzle surface of the second inkjet head is wiped by the relative movement of another one of the inkjet heads, and the second inkjet head wipes the nozzle surface of the second inkjet head with respect to the first inkjet head in a cross direction that intersects with the direction of the relative movement. 3. The inkjet head cleaning method according to claim 2, wherein the inkjet head cleaning method is arranged at intervals of 1 and at a second interval with respect to the direction of the relative movement. The nozzle surfaces of the plurality of inkjet heads are wiped in each of the relative movement between the one first wiper and the inkjet head and the relative movement between the another first wiper and the inkjet head. The method for cleaning an inkjet head according to claim 6 . Wiping the nozzle surface of the first inkjet head by one of the plurality of relative movements between the second wiper and the inkjet head, and the plurality of relative movements between the second wiper and the inkjet head. The nozzle surface of the second inkjet head is wiped by the relative movement of another one of the inkjet heads, and the second inkjet head wipes the nozzle surface of the second inkjet head with respect to the first inkjet head in a cross direction that intersects with the direction of the relative movement. 4. The method of cleaning an inkjet head according to claim 3, wherein the inkjet head cleaning method is arranged at an interval of 1 and at a second interval with respect to the direction of the relative movement. The nozzle surfaces of the plurality of inkjet heads are wiped in each of the relative movement between the one second wiper and the inkjet head and the relative movement between the another second wiper and the inkjet head. The method for cleaning an inkjet head according to claim 8. In an inkjet head cleaning device having a nozzle surface on which a plurality of nozzles for ejecting ink are arranged,
a first wiper having means for holding liquid and performing a first wiping operation of wiping the nozzle surface by moving relative to the inkjet head;
maintenance liquid applying means for applying maintenance liquid to the first wiper ;
an ink purge unit that performs a discharge operation to forcibly discharge ink from the plurality of nozzles;
a second wiper that performs a second wiping operation of wiping the nozzle surface by moving relative to the inkjet head;
a second wiper cleaning means for performing a second wiper cleaning operation of cleaning the second wiper with the maintenance liquid;
a control means for controlling the first wiping operation, the discharge operation, the second wiping operation, and the second wiper cleaning operation;
The control means causes the first wiper to which the maintenance liquid is applied by the maintenance liquid application means to perform the first wiping operation, and causes the ink purging means to perform the discharge operation after performing the first wiping operation. and causing the second wiper cleaning means to perform the second wiper cleaning operation during or after the execution of the discharge operation,
Furthermore, after the ink purging means executes the discharge operation , the second wiper cleaned by the second wiper cleaning operation is used to perform the second wiping operation. In a cleaning device for a plurality of inkjet heads having a nozzle surface on which a plurality of nozzles for ejecting ink are arranged,
a first wiper having means for holding liquid and performing a first wiping operation of wiping the nozzle surface by moving relative to the inkjet head;
maintenance liquid applying means for applying maintenance liquid to the first wiper ;
an ink purge unit that performs a discharge operation to forcibly discharge ink from the plurality of nozzles;
a second wiper that performs a second wiping operation of wiping the nozzle surface by moving relative to the inkjet head ;
control means for controlling the first wiping operation, the ejection operation, and the second wiping operation ;
The control means causes the first wiper to which the maintenance liquid is applied by the maintenance liquid application means to perform the first wiping operation, and after performing the first wiping operation, the ink purging means executes the discharge operation. and causing the second wiper to perform the second wiping operation after performing the ejection operation,
Furthermore, the control means causes relative movement between the first wiper and the inkjet head to be performed a plurality of times in the first wiping operation, and in each relative movement, the An inkjet head cleaning device characterized by wiping the nozzle surface . In a cleaning device for a plurality of inkjet heads having a nozzle surface on which a plurality of nozzles for ejecting ink are arranged,
a first wiper having means for holding liquid and performing a first wiping operation of wiping the nozzle surface by moving relative to the inkjet head;
maintenance liquid applying means for applying maintenance liquid to the first wiper;
an ink purge unit that performs a discharge operation to forcibly discharge ink from the plurality of nozzles;
a second wiper that performs a second wiping operation of wiping the nozzle surface by moving relative to the inkjet head ;
control means for controlling the first wiping operation, the ejection operation, and the second wiping operation ;
The control means causes the first wiper to which the maintenance liquid is applied by the maintenance liquid application means to perform the first wiping operation, and after performing the first wiping operation, the ink purging means executes the discharge operation. and causes the second wiper to perform the second wiping operation after the discharge operation, and further, the control means causes the second wiper and the inkjet head to move relative to each other a plurality of times in the second wiping operation. An inkjet head cleaning device characterized in that the inkjet head cleaning device is configured to wipe the nozzle surface of a different inkjet head among the plurality of inkjet heads during each relative movement. The first wiper is supported by a rotatable support member,
The maintenance liquid applying means has a maintenance liquid storage tank that stores the maintenance liquid,
The support member is connected to the maintenance liquid storage tank,
According to any one of claims 10 to 12 , the first wiper is immersed in the maintenance liquid stored in the maintenance liquid storage tank by rotating the support member. The inkjet head cleaning device described above. The second wiper is further supported by the support member,
The inkjet head cleaning device according to claim 13 , wherein the second wiper is immersed in the maintenance liquid stored in the maintenance liquid storage tank by rotating the support member. a plurality of the first wipers for wiping the nozzle surfaces of each of the plurality of inkjet heads arranged at a first interval in a direction intersecting the direction of the relative movement;
11. The plurality of inkjet heads arranged at the first intervals are wiped by the plurality of first wipers arranged at the first intervals by one of the relative movements. The inkjet head cleaning device described in . The plurality of first wipers are arranged in a direction intersecting the relative movement and at intervals of a predetermined distance with respect to the rotating direction of the support member,
wiping each of the plurality of inkjet heads with each of the plurality of first wipers;
The inkjet head cleaning device according to claim 15 , wherein each of the plurality of inkjet heads is arranged at predetermined intervals in a direction of the relative movement and a direction intersecting the relative movement. . a plurality of second wipers for wiping the nozzle surfaces of each of the plurality of inkjet heads arranged at first intervals in a direction intersecting the direction of relative movement;
12. The plurality of inkjet heads arranged at the first intervals are wiped by the plurality of second wipers arranged at the first intervals by one of the relative movements. The inkjet head cleaning device described in . The plurality of second wipers are arranged in a direction intersecting the relative movement and at intervals of a predetermined distance with respect to the rotating direction of the support member,
wiping each of the plurality of inkjet heads with each of the plurality of second wipers;
18. The inkjet head cleaning device according to claim 17, wherein each of the plurality of inkjet heads is arranged at predetermined intervals in the direction of the relative movement and the direction intersecting the relative movement. The support member is a rotatable rod-shaped shaft having an outer peripheral surface,
at each of a first position on the circumferential surface of the rod-shaped shaft and a second position spaced apart from the first position by a predetermined distance with respect to the rotating direction of the rod-shaped shaft, in a transverse direction intersecting the direction of the relative movement. A plurality of the first wipers for wiping the nozzle surfaces of each of the plurality of inkjet heads arranged at a first interval are arranged in the axial direction of the rod-shaped shaft at intervals corresponding to the first interval,
Further, at each of a third position on the circumferential surface of the rod-shaped shaft and a fourth position spaced apart from the third position by a predetermined distance with respect to the rotating direction of the rod-shaped shaft, arranged at the first interval in the intersecting direction. a plurality of the second wipers for wiping the nozzle surface of each of the plurality of inkjet heads, which are arranged in the axial direction of the rod-shaped shaft at intervals corresponding to the first interval;
The nozzle surfaces of the plurality of inkjet heads are wiped by the plurality of first wipers arranged at the first position.The nozzle surfaces of the plurality of inkjet heads are wiped by the plurality of second wipers arranged at the third position. , the nozzle surfaces of the plurality of inkjet heads whose nozzle surfaces are wiped by the plurality of first wipers arranged at the second position are wiped by the plurality of second wipers arranged at the fourth position; Wipe off,
In a plurality of inkjet heads, the nozzle surfaces of which are wiped by the plurality of first wipers arranged at the second position, the nozzle surfaces are wiped by the plurality of first wipers arranged at the first position. The inkjet head cleaning device according to claim 14, wherein the inkjet head cleaning device is arranged at a second interval in the direction of the relative movement with respect to the plurality of inkjet heads being taken.

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