JP2021137966A - Inkjet head cleaning method and inkjet head cleaning device - Google Patents

Abstract

To provide an inkjet head cleaning method that can reliably remove dirt from a nozzle surface of an inkjet head and maintain a normal ink ejection by the inkjet head, and to provide an inkjet head cleaning device.SOLUTION: An inkjet head cleaning method includes: a first wiping step of wiping out a nozzle surface of an inkjet head by relative movement between a first wiper and the inkjet head while the first wiper is imparted with maintenance liquid; an ink purge step for forcibly discharging ink from a nozzle of the inkjet head after execution of the first wiping step; and a second wiping step of wiping out the nozzle surface by relative movement between a second wiper and the inkjet head after execution of the ink purge step.SELECTED DRAWING: Figure 1

Description

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

In the inkjet drawing device, by continuing the printing operation, ink dust (ink mist) generated at the time of ink ejection adheres to the surface of the nozzle surface formed by the plurality of ink ejection nozzles of the inkjet head and is contaminated. As a result, abnormalities in the ejection state such as nozzle clogging and displacement (twist) in the ejection direction may occur.

Therefore, in an inkjet drawing apparatus, various methods for cleaning the nozzle surface of an inkjet head are generally used in order to maintain normal ink ejection.

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

Japanese Unexamined Patent Publication No. 9-290511

By the way, the ink that adheres to the nozzle surface of the inkjet head and contaminates the nozzle surface may naturally dry due to the vaporization of the solvent.
Due to this natural drying, the ink adhering to the nozzle surface is thickened and dried, and there is a problem that the ink adheres to the nozzle surface and is difficult to remove. Due to this problem, abnormalities in ink ejection such as clogging and twisting of the nozzle of the inkjet head are promoted.

Further, this problem occurs particularly remarkably in an ink that easily dries naturally among inks, and particularly remarkably in a water-based ink in which water is used as a solvent or an alcohol ink in which alcohol is used as a solvent. Further, among the water-based inks, the water-based latex ink in which the resin is dispersed together with the pigment in the solvent is particularly remarkable because the ink tends to thicken.

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

The present invention has been made in view of the above problems, solves the above problems, reliably removes contamination such as ink mist generated on the nozzle surface of the inkjet head, and normally ejects ink by the inkjet head. It provides a sustainable inkjet head cleaning method and an inkjet head cleaning apparatus.

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

That is, in the present invention, the method for cleaning an inkjet head having a nozzle surface on which a plurality of nozzles for discharging a liquid are arranged is defined as a method for cleaning an inkjet head.
A first wiping step in which the nozzle surface is wiped off by relative movement between the first wiper and the inkjet head with the maintenance liquid applied to the first wiper.
After executing the first wiping step, an ink purge step for forcibly ejecting ink from the plurality of nozzles, and an ink purge step.
After executing the ink purge step, it has a second wiper step of wiping the nozzle surface by relative movement of the second wiper and the inkjet head.

Further, in the present invention, in a cleaning device for an inkjet head having a nozzle surface in which a plurality of nozzles for discharging a liquid are arranged.
A first wiper with a means of holding the liquid,
A maintenance liquid applying means for applying the maintenance liquid to the first wiper,
An ink purging means for forcibly ejecting ink from the plurality of nozzles after wiping the nozzle surface by the relative movement of the first wiper to which the maintenance liquid is applied by the maintenance liquid applying means and the inkjet head.
It is configured as an inkjet head cleaning device, characterized by having a second wiper that wipes the nozzle surface by relative movement with the inkjet head after forcibly ejecting ink from the plurality of nozzles by the ink purging means. You may.

Further, 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 for storing the maintenance liquid.
The support member is connected to the maintenance liquid storage tank, and is connected to the maintenance liquid storage tank.
A cleaning device for an inkjet head, 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 may.

Further, in the present invention, the first wiper or the second wiper is a rotatable rod-shaped rod-shaped shaft having an outer peripheral surface.
At each of the first position of the peripheral surface of the rod-shaped shaft and the second position separated from the predetermined position by a predetermined distance with respect to the rotation direction of the rod-shaped shaft, the first position in the intersecting direction intersecting the relative movement direction. A plurality of the first wipers for wiping the nozzle surface of each of the plurality of inkjet heads arranged at intervals are arranged in the axial direction of the rod-shaped shaft and at intervals corresponding to the first interval.
Further, the rod-shaped shaft is arranged at the third position on the peripheral surface of the rod-shaped shaft and at each of the fourth positions separated from the third position by a predetermined distance with respect to the rotation direction of the rod-shaped shaft at the first interval in the crossing direction. A plurality of the second wipers for wiping the nozzle surface of each of the plurality of inkjet heads are arranged in the axial direction of the rod-shaped shaft and at intervals corresponding to the first interval.
The nozzle surface is wiped off by the plurality of first wipers arranged at the first position. The nozzle surface of the plurality of inkjet heads is wiped off 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 off by the plurality of first wipers arranged at the second position are covered by the plurality of second wipers arranged at the fourth position. Wiping,
The nozzle surface is wiped off by the plurality of first wipers arranged at the second position, and the nozzle surface is wiped by the plurality of first wipers arranged at the first position. It may be configured as an inkjet head cleaning device characterized in that the plurality of inkjet heads to be taken are arranged at a second interval in the direction of the relative movement.

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

It is a schematic front view of the inkjet drawing apparatus which is one Embodiment of this invention. It is a schematic plan view of the inkjet drawing apparatus which is one Embodiment of this invention. It is a schematic cross-sectional view of the cleaning unit which is one Embodiment of this invention. It is sectional drawing of the water retention wiper and the blade wiper which are one Embodiment of this invention. It is a front view of the water retention wiper and the blade wiper which are one Embodiment of this invention. It is a flowchart which shows the cleaning sequence of the inkjet head which is one Embodiment of this invention. It is a schematic diagram which shows the contamination state of an inkjet head. It is a bottom view of the inkjet head nozzle surface side of the carriage on which a plurality of inkjet heads according to the embodiment of the present invention are mounted. It is a perspective view of the wiper unit which comprises the cleaning unit which is one Embodiment of this invention. It is a side view of the wiper unit which comprises the cleaning unit which is one Embodiment of this invention. It is a front view of the wiper unit which comprises the cleaning unit which is one Embodiment of this invention. It is a block diagram which shows the electrical structure of the inkjet drawing apparatus which is one Embodiment of this invention. It is a block diagram which shows the electrical structure about the ink supply path in the inkjet drawing apparatus which is one Embodiment of this invention.

Hereinafter, embodiments of the present invention will be described in detail 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 according to an embodiment of the present invention, and FIG. 2 is a plan view of an inkjet drawing apparatus according to an embodiment of the present invention.

The inkjet drawing apparatus 1 in this embodiment has 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 the present embodiment, the nozzle surface has a rectangular shape. These plurality of nozzles are arranged side by side in the longitudinal direction (X-axis direction) of the nozzle surface.

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

An X-axis moving means 15 for moving the carriage 13 substantially horizontally is connected to the carriage 13.
The X-axis moving means moves the carriage 13 above the platen on which the recording medium is placed during printing, and retracts it from above the platen during non-printing and cleaning of the inkjet head 11 and above the cleaning unit 3. Move. In the present embodiment, the X-axis moving means 15 is arranged so as to move in a direction (X-axis direction) substantially orthogonal to the recording medium transport direction (Y-axis direction).
As the X-axis moving means, it is preferable to use a linear motor which is a drive system that moves linearly, and an appropriate one such as a linear motor, a ball screw, and a timing belt is used. A linear motor is used in this embodiment.

Further, a Z-axis moving means 17 for moving the carriage 13 in the vertical direction (Z-axis direction) is connected to the carriage 13.
Servo motors, stepping motors, etc. are used as the Z-axis moving means. A servo motor is used in this embodiment. It is preferable that the Z-axis moving means is provided with a braking means for preventing the fall.

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

A maintenance liquid storage tank in which a wiper unit 7 composed of a blade wiper 21 connected to a rod-shaped shaft 19 and a water-retaining wiper 23 connected to the cleaning unit 3 rotatably stores the maintenance liquid. It is connected to 26.

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

When executing the cleaning sequence, the cleaning unit 3 moves the carriage 13 to the cleaning position above the cleaning unit 3 by driving the X-axis moving means 15 to execute the cleaning sequence.
Further, the capping unit 5 for blocking the nozzle surface of the inkjet head 11 from the outside air during non-printing to prevent ink drying and storing the inkjet head 11 is adjacent to the cleaning unit 3 and can move substantially horizontally in the Y-axis direction. It is connected to the Y-axis moving means 29 and is arranged above (Z-axis direction) with respect to the cleaning unit 3.

At the time of capping, the capping unit 5 moves to the upper part of the cleaning unit 3. On the other hand, the carriage 13 moves above the capping unit 5 and then descends by the shaft moving means 17. As a result, the nozzle surface of the inkjet head 11 is connected to the capping rubber 31 constituting the capping unit 5 for capping.
During printing and when performing a cleaning sequence, the capping unit 5 is horizontally moved from above the cleaning unit 3 and retracted.
As the Y-axis moving means, a linear motor is used as in the X-axis moving means, and appropriate ones such as a linear motor, a ball screw, and a timing belt are used.

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

FIG. 12 is a block diagram showing an 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, a memory, and the like.

The memory is composed of, for example, RAM and ROM, and the calculation result of the CPU and the printed image data are temporarily recorded in the RAM. Further, in the ROM, in addition to the cleaning sequence execution program as shown in the flowchart shown in FIG. 6, the inkjet head 11 and the control program for driving and controlling the various moving means of the X, Y, and Z axes described above are contained in the ROM. It is stored.

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

Then, the controller 43 drives and controls the linear motion motor 53 constituting the X-axis moving means 15 via the motor drive driver 45, and drives the drive motor 55 constituting the Z-axis moving means via the motor drive driver 47. I'm in control. Further, the drive motor 51 for rotating the rod-shaped shaft 19 described later is driven and controlled via the motor drive driver 49.

FIG. 13 is a block diagram showing an electrical configuration for controlling an inkjet head and an 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 the control computer 41 and the controller 43.
The controller 43 is connected to the motor 65 that drives the tube pump via the motor control driver 62.
In response to a command from the controller 43, the motor 65 is driven, and ink is supplied from the ink tank 61 in which the ink is stored to the sub tank 67 that adjusts the air pressure in the ink path via the tube 63. More specifically, the sub tank 67 is equipped with a liquid level sensor, and the controller 43 drives the motor 65 by the signal of the liquid level sensor connected to the sub tank 67, and a set amount of ink is supplied to the sub tank 67. Is controlled.

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

More specifically, in a normal state, the pressure in the sub tank is maintained at a negative pressure to prevent ink from leaking from the nozzle of the inkjet head 11. When performing the ink purge described later, by switching the pressure in the sub tank 69 to a positive pressure by the above control, the ink supplied in the sub tank 69 is pushed out from the nozzle of the inkjet head 11 by the positive pressure, and the ink is ejected from the nozzle. It is forcibly discharged. In addition, by controlling the time for applying positive pressure, the amount of forced ink discharge by ink purging 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 the maintenance liquid is stored, and an ink purge tray 27.

In the wiper unit 7, the first wiper and the second wiper are radially parallel to the axial center of the rod-shaped shaft 19 and one end of the rectangle is substantially parallel to the axial direction of the rod-shaped shaft 19. Is supported by. In the present 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 the present embodiment, the first wiper will be described as a water-retaining wiper 23, and the second wiper will be described as a blade wiper 21.

The cross-sectional shape of the rod-shaped shaft 19 retains water when the water-retaining wiper 23 or the blade wiper 21 comes into contact with the nozzle surface of the inkjet head 11 so that the nozzle surface of the inkjet head 11 can be wiped uniformly during the cleaning sequence. The distance between the outer peripheral point of the rod-shaped shaft 19 to which the 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 the direction substantially perpendicular to the nozzle surface is uniform. It is preferable that it is. For example, a cylindrical shape or a regular polygonal shape is assumed. In this embodiment, it has a regular polygonal shape and a regular hexagon.
A drive motor 51 for rotating the rod-shaped shaft 19, the water-retaining wiper 23 and the blade wiper 21 connected to the rod-shaped shaft 19 about the axis of the rod-shaped shaft 19 is connected to the end 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 driving and controlling the drive motor 51, 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 brought into contact with each other during the cleaning sequence. The operation of immersing 21 in the maintenance liquid stored in the maintenance liquid storage tank 26 for cleaning can be performed.

The drive motor 51 preferably can 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 preferable.
In the present embodiment, both the water-retaining wiper 23 and the blade wiper 21 are connected to one rod-shaped shaft 19, but if the configuration includes both the water-retaining wiper and the blade wiper, Confirm that the configuration may be divided into a plurality of rod-shaped shafts and connected, or other configurations may be used.

Here, the structures of the water-retaining wiper 23 and the blade wiper 21 will be described.
FIG. 4 is a cross-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 the present embodiment, as shown in FIG. 5, both the water-retaining wiper 23 and the blade wiper 21 are formed in a thin rectangular shape. It is effective that each wiper has a shape that covers the short side (width direction) of the nozzle surface of the inkjet head 11 so that the ink on the nozzle surface can be reliably removed.

As described later, the material of the water-retaining wiper 23 needs to be a material having water-retaining ability to retain the liquid in order to wipe the nozzle surface of the inkjet head 11 in a state of absorbing and holding the maintenance liquid. ..
Therefore, a porous material having a high water retention rate and containing a continuous pore structure inside is preferable. For example, it may be composed of a sponge-like continuous foam such as urethane, polystyrene, polypropylene, or polyethylene, a woven fabric, a non-woven 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 is immersed in ink, so that it has chemical resistance. It is preferable that the material has isochemical stability. For example, silicone rubber (Si, Q), ethylene / propylene rubber (EPM), ethylene / propylene / diene rubber (EPDM), fluororubber (FKM), and the like are assumed.

Then, when the maintenance liquid storage tank 26 in which the maintenance liquid is stored under the wiper unit 7 rotates the wiper unit 7, the water-retaining wiper 23 or the blade wiper 21 is immersed in the stored maintenance liquid. It is arranged so that it can be washed.

As the maintenance liquid used in the maintenance unit, an ink capable of dissolving and cleaning the ink is appropriately selected and used according to the type and characteristics of the ink used in the inkjet drawing apparatus 1.

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

The cleaning sequence is appropriately executed as needed, for example, when the inkjet drawing apparatus 1 is started, before the start of printing, before the capping of the inkjet head after the end of printing, and the like.

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

First, before carrying out the first wiping step, the water-retaining wiper cleaning step of Flow 2 is carried out. This keeps the water-retaining wiper 23 clean, prevents impurities from adhering to the nozzle surface of the inkjet head 11, and immerses the maintenance liquid in the water-retaining wiper 23 before executing the first wiping step. The purpose is to supply and impart the water-retaining wiper 23. Other methods can be assumed as the means for applying the maintenance liquid to the water-retaining wiper 23, and for example, a method of providing a supply path for supplying the maintenance liquid inside the water-retaining wiper 23 can be assumed.

In the present 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, the first wiping step is executed. The configuration of the first wiping step will be described.

First, the water-retaining wiper standby step in which the water-retaining wiper 23 is arranged so as to face the nozzle surface and substantially orthogonal to the nozzle surface, as shown in Flow 2, is executed so that the nozzle surface can be wiped by the water-retaining wiper 23.

In the present 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 to rotate the wiper unit 7 substantially vertically. Place in.

Next, the water-retaining wiper wiper 23 of Flow 3 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 off the nozzle surface, thereby performing water-retaining wiper wiping.

In the present embodiment, the control computer 41 issues a command to the controller 43, and the linear motor 53 is driven via the motor drive driver 45 to drive the X-axis moving means 15, and the inkjet head 11 mounted on the carriage 13. Is moved to above the water-retaining wiper 23, which is arranged substantially vertically facing the nozzle surface.

Next, a command is issued from the control computer 41 to the controller 43, the drive motor 55 is driven via the motor drive driver 47 to drive the Z-axis moving means 17, and the inkjet head 11 mounted on the carriage 13 is moved to the Z-axis. It is lowered in the direction to bring the nozzle surface into contact with the tip of the water-retaining wiper 23. At this time, if the inkjet head 11 is moved so that the water-retaining wiper 23 comes into contact with one end of the nozzle surface in the longitudinal direction (X-axis direction), the wiper can be wiped more efficiently.

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 substantially in parallel while maintaining the state in which the nozzle surface and the tip of the water-retaining wiper 23 are in contact with each other. Then, the flow 3 is executed.

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, so that the inkjet head is used during printing or the like. This is because the ink adhering to the nozzle surface of No. 11 and dried and thickened is reduced in viscosity with a cleaning liquid to make it easier to wipe off from the nozzle surface.

That is, when the ink mist generated during inkjet printing adheres to the nozzle surface, especially when an ink such as a water-based ink that dries easily and easily thickens is used, the thickening increases due to the vaporization of the solvent, as shown in FIG. 7α. The viscous ink 33 is deposited on the nozzle surface. When the ink adhering to the nozzle surface is to be wiped off with an elastic wiper such as rubber while the ink is thickened, the thickening ink 33 exhibits adhesion to the nozzle surface, and as a result, the ink is thickened by the wiper. As shown in FIG. 7β, the thickening ink 33 is spread on the nozzle surface instead. As a result, the thickened ink causes nozzle clogging, and in the worst case, the inkjet head 11 is damaged. Further, it may be difficult to sufficiently remove the thickened ink even by the ink purge described later, and if the thickened ink is not completely removed, nozzle clogging is induced.

Therefore, since it is effective to lower the viscosity of the adhered ink, in the present embodiment, the thickening ink 33 is melted by lowering the viscosity with the maintenance liquid by performing wiping with the water-retaining wiper 23 holding the maintenance liquid. While wiping is performed, the thickening ink 33 is removed.

In the first wiping step, when a plurality of inkjet heads 11 are mounted on the carriage 13, the flow 2 and the flow 3 are repeatedly executed according to the flowchart of FIG. 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 repeatedly executing the flow 2 and the flow 3 as necessary according to the flow of FIG.

Next, the ink purge step of the flow 4 will be described.
In the flow 4, ink is forcibly discharged (ink purged) from a plurality of nozzles constituting the nozzle surface of the inkjet head 11 to clean the inside of the nozzles.

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

In the present embodiment, the carriage 13 is moved in the X-axis direction, the carriage 13 is retracted from the maintenance liquid storage tank 26, and is 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, and the pressure in the sub tank 69 is switched to the positive pressure, so that the ink in the sub tank 69 is injected into the inkjet head by the air pressure. Supply to 11. As a result, the ink is forcibly discharged from the nozzle of the inkjet head 11.

Further, the time for applying the positive pressure is controlled according to the usage condition of the inkjet head 11, and the amount of forced ink discharge by the ink purge is adjusted. Further, 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 invades and unnecessarily contaminates the stored maintenance liquid. To avoid.

Here, the purpose of carrying out the ink purge step after the first wiping step will be described.

When the nozzle surface is moistened with a large amount of cleaning liquid by the first wiping step and wiping is performed by the water-retaining wiper 23, the diameter of the nozzle (orifice) constituting the nozzle surface is very small, so that the cleaning liquid is generated by the capillary phenomenon. It penetrates into the nozzle and the maintenance liquid gets mixed in the ink near the nozzle.

In inkjet printing, it is necessary to control the meniscus of the ink (curved surface formed on the surface of the ink in the nozzle by the interfacial tension of the ink) in the nozzle portion of the inkjet head 11 to an appropriate shape for stable ink ejection. .. However, when the maintenance liquid is mixed with the ink in the nozzle, the characteristics of the interfacial tension of the ink in the nozzle change, and as a result, the predetermined meniscus shape cannot be maintained and the meniscus is destroyed. Therefore, if printing is performed as it is, an abnormality in ink ejection occurs and the print image quality is deteriorated.

In order to prevent this problem only with a water-retaining wiper such as a sponge or a non-woven fabric and to complete the cleaning of the inkjet head 11 only with the first wiping step, the amount of maintenance liquid held by the water-retaining wiper is controlled. There is a need. However, for that purpose, introduction of a mechanism for squeezing the water-retaining wiper to a predetermined maintenance liquid retention amount, introduction of control of the squeezing amount, or introduction of a mechanism for controlling the maintenance liquid amount applied to the water-retaining wiper and its control. Is required. In addition to requiring difficult control to realize such a method, the mechanical configuration of the cleaning unit and the entire inkjet drawing apparatus 1 becomes extremely complicated and expensive.

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

Immediately after the ink purge step of flow 4 is completed, or during the execution of flow 4, the blade wiper cleaning step of flow 5 is performed. This is intended to keep the blade wiper 21 clean and prevent impurities from adhering to the nozzle surface of the inkjet head 11 prior to performing the second wiping step.

In the present 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 the flow 4 and the flow 5 are completed, the second wiping step is executed. The configuration of the second wiping step will be described.

First, in the flow 6, a blade wiper standby step is executed in which the blade wiper 21 is arranged so as to face the nozzle surface and substantially orthogonal to the nozzle surface so that the blade wiper 21 can wipe the nozzle surface. In the present embodiment, the wiper unit 21 is rotated and the blade wiper 21 is arranged substantially vertically above.

Next, the blade wiper 21 of the flow 7 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 off the nozzle surface, and wiping is performed by the blade wiper.

In the present embodiment, the control computer 41 issues a command to the controller 43, and the linear motor 53 is driven via the motor drive driver 45 to drive the X-axis moving means 15, and the inkjet head 11 mounted on the carriage 13. Is moved to above the blade wiper 21 which is arranged substantially vertically facing the nozzle surface.
Next, a command is issued from the control computer 41 to the controller 43, the drive motor 55 is driven via the motor drive driver 47 to drive the Z-axis moving means 17, and the inkjet head 11 mounted on the carriage 13 is moved to the Z-axis. It is lowered in the direction to bring the nozzle surface into contact with the tip of the blade wiper 21. 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), wiping can be performed more efficiently.
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 substantially 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. , Flow 7 is executed.

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

At this stage, since the time from the execution of the flow 4 to the execution of the 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 the present embodiment, the blade wiper 21 is formed of an elastic body having no water retention. Therefore, there is a possibility that some maintenance liquid is attached to the nozzle due to the holding flow 5, but since the cleaning liquid that the cleaning liquid is mixed in due to the capillary phenomenon is not held in the nozzle, the ink meniscus is destroyed by the mixing of the cleaning liquid. Does not occur.

When a plurality of inkjet heads 11 are mounted on the carriage 13, the flow 6 and the flow 7 are repeatedly performed in the same manner as in the first wiping step, and all the inkjet heads mounted on the carriage 13 are mounted. Wiping the nozzle surface of the head 11.

By executing the above flow, the second wiping step is completed, and all the cleaning sequences according to the present embodiment are completed.

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

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

In an inkjet printer, when it is necessary to print in a wide width at one time, a plurality of inkjet heads are overlapped in the nozzle row direction in which the nozzles of the inkjet heads are lined up in a predetermined row so that the nozzle rows of the inkjet heads 11 overlap each other. A method of arranging them on a carriage is generally performed.

As an arrangement method in which the inkjet heads are arranged so as to overlap each other, an appropriate method is assumed depending on the shape of the inkjet heads, but as an example, in the case of the inkjet head 11 in the present 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 adjacent to each other on a straight line at intervals in the longitudinal direction (nozzle row direction), and the inkjet heads 11 on which the inkjet heads 11 are arranged are arranged. The nozzle rows are arranged parallel to the nozzle row direction and at vacant intervals so that the ends of the nozzle rows forming the nozzle surfaces of all the inkjet heads 11 overlap each other.

In such an overlapping arrangement of the inkjet heads 11, for example, when the recording medium passes under the nozzle surface of the inkjet head 11 once, all the inks necessary for image formation are applied to complete printing. It is applied in the case of the so-called one-pass method in which the printing is performed, or in the case where it is necessary to widen the printable width by one scanning and improve the production tact.

In this case, when wiping is performed from one end to the other end of the nozzle surface in the nozzle row direction, if the nozzle surfaces of all the arranged inkjet heads 11 are wiped at once, they are arranged. 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 is wiped at the same time.

If the wiper is wiped to the bottom surface of the carriage 13 in this way, there is a problem that impurities adhering to the bottom surface of the carriage 13 are spread on the nozzle surface of the inkjet head 11, and there is a gap between the bottom surface of the carriage 13 and the nozzle surface of the inkjet head 11. There is also a problem that the wiper comes into contact and damages the wiper.

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

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

Regarding the method of setting such an inkjet head group, if the nozzle surface of the inkjet head 11 is rectangular as shown in FIG. 8, the inkjet head 11 intersects the X-axis direction, which is the direction in which the inkjet head 11 is moved by the X-axis moving means 15. A plurality of inkjet heads 11 arranged at predetermined intervals in the direction of the nozzle 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 and one end of the inkjet head 11 in the longitudinal direction 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, the two inkjet heads 11 indicated by α and the two inkjet heads 11 indicated by β each form one inkjet head group. Further, with respect to the inkjet heads 11 constituting the inkjet head group α, a predetermined interval is provided in the X-axis direction, which is the direction in which the inkjet head 11 is moved by the X-axis moving means 15, and in the Y-axis direction intersecting the X-axis direction. The two inkjet heads 11 indicated by γ, which are arranged, form one inkjet head group. Here, it 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 the present embodiment, it is a regular hexagon. As the number of rows of inkjet heads 11 to be wiped increases, and as the number of inkjet head groups increases, it can be assumed that the polygonal shape or the circular shape is further increased.

Then, as shown in FIGS. 9 and 11, the inkjet head 11 is arranged on the surface of the outer peripheral surface of the rod-shaped shaft 19 which constitutes one regular hexagonal side of the plurality of water-retaining wipers 23 for realizing the first wiping step. They are arranged side by side in a row according to the intervals. With the arrangement of the inkjet heads 11 shown in FIG. 8, the water-retaining wiper 23 is also arranged at a predetermined distance between the two inkjet heads 11 indicated by α. The plurality of water-retaining wipers 23 arranged in a row in this way are referred to as one water-retaining wiper group, and will be described here as the water-retaining wiper group A.

Further, as shown in FIGS. 9 to 11, the plurality of water-retaining wipers 23 are arranged on the outer circumference of the rod-shaped shaft 19 whose circumference is shifted from the outer peripheral surface on which the water-retaining wiper group is arranged with respect to the center of the rotation axis of the rod-shaped shaft 19. The water-retaining wiper 23 arranged earlier is arranged on the other regular hexagonal side of the surface so as to be displaced from the position of the rod-shaped shaft 19 in the axial direction. In the arrangement of the inkjet heads 11 shown in FIG. 8, the water-retaining wiper 23 is also arranged in accordance with the distance between the two inkjet heads 11 indicated by γ. The plurality of water-retaining wipers 23 arranged in a row in this way are referred to as another water-retaining wiper group, and here, the water-retaining wiper group B. As the number of rows of inkjet heads 11 to be wiped increases and as the number of inkjet head groups increases, the water-retaining wiper groups C and D and the water-retaining wiper groups are similarly increased.

Further, as shown in FIGS. 9 and 11, a plurality of blade wipers 21 for realizing the second wiping step previously set the water-retaining wiper group A and the water-retaining wiper group B in the same manner as the arrangement of the water-retaining wiper 23. The inkjet head 11 is arranged at a predetermined interval on the surface forming another regular hexagonal side of the outer peripheral surface of the rod-shaped shaft 19 whose circumference is deviated from the arranged outer peripheral surface with respect to the center of the rotation axis of the rod-shaped shaft 19. Arranged side by side in a row. In the arrangement of the inkjet heads 11 shown in FIG. 8, the blade wiper 21 is also arranged according to the distance between the two inkjet heads 11 indicated by α. The plurality of blade wipers 21 arranged in a row in this way are referred to as one blade wiper group, and will be described here as the blade wiper group A.

Further, as shown in FIGS. 9 to 11, the plurality of blade wiper groups have a rod-like shape whose circumference is shifted from the outer peripheral surface on which the water-retaining wiper group and the blade wiper group are arranged so far with respect to the center of rotation of the rod-shaped shaft 19. The blade wiper 21 arranged earlier is arranged on the surface forming another regular hexagonal side of the outer peripheral surface of the shaft 19 so as to be displaced from the position of the rod-shaped shaft 19 in the axial direction. In the arrangement of the inkjet heads 11 shown in FIG. 8, the blade wiper 21 is also arranged according to the distance between the two inkjet heads 11 indicated by γ. The plurality of blade wipers 21 arranged in a row in this way are referred to as another blade wiper group, and here, the blade wiper group B. As the number of rows of inkjet heads 11 to be wiped increases and as the number of inkjet head groups increases, the water-retaining wiper groups C and D and the water-retaining wiper groups are similarly increased.

As described above, the wiper unit 7 is configured. It is not always necessary to configure the wiper unit 7 with only one rod-shaped shaft 19, and each wiper group may be appropriately divided and arranged by using a plurality of rod-shaped shafts 19 as necessary, and the wiper unit does not rotate. Confirm that the method may be used.

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

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

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

Further, a case where the second wiping step is performed on the plurality of inkjet heads 11 arranged as shown in FIG. 8 will also be described. First, the first second wiping step is performed on the inkjet head group α using the blade wiper group A.
Next, the second wiping step is performed on the inkjet head group α and the inkjet head group β aligned in the longitudinal direction of the nozzle surface of the inkjet head 11 by using the blade wiper group A.

Then, the wiper unit 7 is rotated, and the third second wiping step is performed 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 the inkjet heads 11.

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

For example, a plurality of water-retaining wipers 23 are placed on one surface forming a regular hexagonal side of the outer peripheral surface of the rod-shaped shaft 19, and in the example of FIG. 8, the water-retaining wipers 23 are placed on the inkjet head group α and the inkjet head group. Four sheets are arranged according to the interval of γ. However, when the first wiping step is performed 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 the inkjet head group α is wiped, the inkjet head group α and the inkjet head group α are combined. Since the starting point of wiping is different between the inkjet head group γ and the inkjet head group γ, wiping is performed up to the bottom surface of the carriage 13 in the nozzle row direction of the inkjet head group γ. In such a process, there arises a problem of wiping the bottom surface of the carriage 13.

Therefore, by arranging the water-retaining wiper group A and the water-retaining wiper group B separately as described above, water retention for wiping the inkjet head group γ when wiping the inkjet head group α or the inkjet head group β is performed. Since the sex 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, the cleaning sequence can be appropriately performed even when a plurality of inkjet heads 11 are provided.

1 Inkjet drawing device 3 Cleaning unit 5 Capping unit 7 Wiper unit 11 Inkjet head 13 Carriage 15 X-axis moving means 17 Z-axis moving means 19 Rod-shaped shaft 21 Blade wiper 23 Water-retaining wiper 26 Maintenance liquid storage tank 27 Ink purge tray 29 Y-axis Transportation 33 Thickening ink 41 Control computer 43 Controller 45 Motor drive driver 47 Motor drive driver 49 Motor drive driver 51 Drive motor 53 Linear 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 (18)

In a method of cleaning an inkjet head having a nozzle surface in which a plurality of nozzles for discharging a liquid are arranged,
A first wiping step in which the nozzle surface is wiped off by relative movement between the first wiper and the inkjet head with the maintenance liquid applied to the first wiper.
After executing the first wiping step, an ink purge step for forcibly ejecting ink from the plurality of nozzles, and an ink purge step.
A method for cleaning an inkjet head, which comprises a second wiping step in which the nozzle surface is wiped off by relative movement of the second wiper and the inkjet head after executing the ink purge step. The first wiping step includes a step of arranging the first wiper facing the nozzle surface, a step of moving the inkjet head to a wiping start position where the nozzle surface and the first wiper come into contact with each other, and the step of moving the inkjet head. It is composed of steps of relatively moving the inkjet head and the first wiper in a state where the nozzle surface and the first wiper are in contact with each other.
The second wiper step includes a step of arranging the second wiper so as to face the nozzle surface, a step of moving the inkjet head to a wiping start position where the nozzle surface and the second wiper come into contact, and the step of moving the inkjet head. The method for cleaning an inkjet head according to claim 1, further comprising a step of relatively moving the inkjet head and the second wiper in a state where the nozzle surface and the second wiper are in contact with each other. Before carrying out the first wiper step, the first wiper washing step of washing the first wiper with the maintenance liquid is carried out.
The method for cleaning an inkjet head according to claim 1 or 2, wherein a second wiper cleaning step of cleaning the first wiper with the maintenance liquid is performed before the second wiper step is performed. Claims 1 to 3, wherein in the first wiping step, the relative movement of the first wiper and the inkjet head is executed a plurality of times, and different nozzle surfaces are wiped off in each relative movement. The method for cleaning an inkjet head according to any one item. The nozzle surface of the first inkjet head is wiped off by one of the relative movements of the first wiper and the inkjet head a plurality of times, and the relative movement of the first wiper and the inkjet head a plurality of times. The nozzle surface of the second inkjet head is wiped off by the relative movement of another one of the two inkjet heads, and the second inkjet head with respect to the first inkjet head with respect to the crossing direction intersecting the direction of the relative movement. The method for cleaning an inkjet head according to any one of claims 1 to 4, wherein the inkjet heads are arranged at an interval of 1 and at a second interval with respect to the direction of relative movement. The nozzle surface of a plurality of inkjet heads is wiped off in each of the relative movement of the first wiper and the inkjet head and the relative movement of the other first wiper and the inkjet head. The method for cleaning an inkjet head according to claim 5. Claims 1 to 6, wherein in the second wiping step, the relative movement of the second wiper and the inkjet head is executed a plurality of times, and different nozzle surfaces are wiped off in each relative movement. The method for cleaning an inkjet head according to any one item. The nozzle surface of the first inkjet head is wiped off by one of the relative movements of the second wiper and the inkjet head a plurality of times, and the relative movement of the second wiper and the inkjet head a plurality of times. The nozzle surface of the second inkjet head is wiped off by the relative movement of another one of the two inkjet heads, and the second inkjet head with respect to the first inkjet head with respect to the crossing direction intersecting the direction of the relative movement. The method for cleaning an inkjet head according to any one of claims 1 to 7, wherein the inkjet heads are arranged at an interval of 1 and at a second interval with respect to the direction of relative movement. The nozzle surface of a plurality of inkjet heads is wiped off in each of the relative movement of the second wiper and the inkjet head and the relative movement of the other 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 in which a plurality of nozzles for discharging a liquid are arranged.
A first wiper with a means of holding the liquid,
A maintenance liquid applying means for applying the maintenance liquid to the first wiper,
An ink purging means for forcibly ejecting ink from the plurality of nozzles after wiping the nozzle surface by the relative movement of the first wiper to which the maintenance liquid is applied by the maintenance liquid applying means and the inkjet head.
An inkjet head cleaning device comprising a second wiper that forcibly ejects ink from the plurality of nozzles by the ink purging means and then wipes the nozzle surface by relative movement with the inkjet head. The first wiper or the second wiper is supported by a rotatable support member, and 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 for storing the maintenance liquid.
The support member is connected to the maintenance liquid storage tank, and is connected to the maintenance liquid storage tank.
The inkjet head according to claim 10, wherein 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. Cleaning equipment. The inkjet head cleaning device according to claim 10 or 11, wherein the relative movement of the first wiper and the inkjet head is executed a plurality of times, and different nozzle surfaces are wiped off in each relative movement. .. A plurality of the first wipers for wiping the nozzle surface of each of the plurality of inkjet heads arranged at the first interval in a direction intersecting the direction of the relative movement are arranged at the first interval.
10. A aspect of claim 10, wherein the plurality of inkjet heads arranged at the first interval are wiped off by the plurality of first wipers arranged at the first interval by the relative movement of one. The inkjet head cleaning device according to any one of claims 12. A plurality of the first wipers are arranged at intervals that intersect the relative movement and are separated by a predetermined distance with respect to the rotation direction of the support member.
Each of the plurality of inkjet heads to be arranged is wiped off with each of the plurality of first wipers.
The invention according to any one of claims 10 to 13, wherein each of the plurality of inkjet heads is arranged at a predetermined interval in the direction of the relative movement and in the direction intersecting the relative movement. The inkjet head cleaning device described. The aspect according to any one of claims 10 to 14, wherein the relative movement of the second wiper and the inkjet head is executed a plurality of times, and different nozzle surfaces are wiped off in each relative movement. Inkjet head cleaning device. A plurality of the second wipers for wiping the nozzle surface of each of the plurality of inkjet heads arranged at the first interval in a direction intersecting the direction of the relative movement are arranged at the first interval.
10. A aspect of claim 10, wherein the plurality of inkjet heads arranged at the first interval are wiped off by the plurality of second wipers arranged at the first interval by the relative movement of one. The inkjet head cleaning device according to any one of claims 15. A plurality of the second wipers are arranged at intervals that intersect the relative movement and are separated by a predetermined distance with respect to the rotation direction of the support member.
Each of the plurality of inkjet heads to be arranged is wiped off with each of the plurality of second wipers.
The invention according to any one of claims 10 to 16, wherein each of the plurality of inkjet heads is arranged at a predetermined interval in the direction of the relative movement and in the direction intersecting the relative movement. The inkjet head cleaning device described. The first wiper or the second wiper has an outer peripheral surface and is a rotatable rod-shaped rod-shaped shaft.
At each of the first position of the peripheral surface of the rod-shaped shaft and the second position separated from the predetermined position by a predetermined distance with respect to the rotation direction of the rod-shaped shaft, the first position in the intersecting direction intersecting the relative movement direction. A plurality of the first wipers for wiping the nozzle surface of each of the plurality of inkjet heads arranged at intervals are arranged in the axial direction of the rod-shaped shaft and at intervals corresponding to the first interval.
Further, the rod-shaped shaft is arranged at the third position on the peripheral surface of the rod-shaped shaft and at each of the fourth positions separated from the third position by a predetermined distance with respect to the rotation direction of the rod-shaped shaft at the first interval in the crossing direction. A plurality of the second wipers for wiping the nozzle surface of each of the plurality of inkjet heads are arranged in the axial direction of the rod-shaped shaft and at intervals corresponding to the first interval.
The nozzle surface is wiped off by the plurality of first wipers arranged at the first position. The nozzle surface of the plurality of inkjet heads is wiped off 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 off by the plurality of first wipers arranged at the second position are covered by the plurality of second wipers arranged at the fourth position. Wiping,
The plurality of inkjet heads whose nozzle surface is wiped by the plurality of first wipers arranged at the second position has the nozzle surface wiped by the plurality of first wipers arranged at the first position. The inkjet head cleaning apparatus according to claim 10, wherein the plurality of inkjet heads to be taken are arranged at a second interval in the direction of the relative movement.

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