JP7680235B2 - Liquid ejection device and inkjet printing device - Google Patents

Description

The present invention relates to a liquid discharge device that discharges a specified liquid to the outside via a flow path, and an inkjet printing device equipped with the liquid discharge device.

Conventionally, inkjet printing devices have been proposed that print by ejecting ink from an inkjet head onto print media such as paper and film.

In inkjet printing devices, ink can stick to the ink ejection openings of the nozzles, or dirt such as paper dust from the paper can adhere to them. If ink sticks to the ink ejection openings of the nozzles or paper dust accumulates, ejection problems such as misalignment of the ink ejection direction from the nozzles or failure to eject ink can occur.

To reduce such ejection defects, a series of operations is known in which ink is forcibly ejected from the nozzles of the inkjet head, a process known as purging, and then a wiper is used to wipe the ink ejection openings of the nozzles.

To perform this series of operations, for example, Patent Document 1 proposes an inkjet printing device that includes a wiping unit with a wiper and a capping unit with a cap portion that receives ink ejected from the inkjet head during purging.

The cap part seals the ink ejection surface of the inkjet head to prevent the ink from drying out, but as mentioned above, it also serves the role of receiving the ink ejected from the inkjet head during purging.

In the wiping unit, after cleaning the ink ejection surface with a wiper, the wiper is immersed in a cleaning liquid tank filled with cleaning liquid to clean the wiper itself. The cleaning liquid in the cleaning liquid tank is then discarded at regular intervals.

In the capping unit, the ink received by the cap is sucked up by a pump or the like and disposed of in a waste tank via a flow path such as a tube.

JP 2018-149461 A

However, because the amount of ink ejected from the inkjet head during purging is extremely small, the amount of waste liquid discharged into the tubes and other flow paths is also extremely small. Furthermore, because the distance from the capping unit to the waste liquid tank is long, the ink discarded by purging can dry out in the tubes and other flow paths, increasing its viscosity and solidifying, which can lead to the problem of tube clogging.

The present invention aims to provide a liquid discharge device and an inkjet printing device that can prevent liquid discharged from a cap from solidifying and clogging the flow path to a waste liquid tank.

The liquid discharge device of the present invention includes a cap-side flow path through which the discharged liquid is discharged into a cap section that seals the discharge port of a discharge section that has a discharge port for discharging the liquid, and a wiper-side flow path through which cleaning liquid is discharged from a wiping section that wipes the discharge port of the discharge section, and has a junction where the cap-side flow path and the wiper-side flow path join, and a single flow path is formed from the junction.

The liquid discharge device of the present invention has a junction where the cap side flow path and the wiper side flow path join, and the same flow path is formed from the junction. This allows the cleaning liquid discharged from the wiping section to flow into the same flow path via the wiper side flow path, thereby preventing the liquid discharged from the cap section from solidifying and clogging the flow path to the waste liquid tank.

FIG. 1 is a schematic diagram showing the configuration of an inkjet printing apparatus using an embodiment of a liquid ejection device according to the present invention; FIG. 2 is a view of the inkjet printing apparatus shown in FIG. 1 from the direction of the arrow A. FIG. 1 is a diagram showing a schematic configuration of an example of a head unit; FIG. 2 is a diagram showing a schematic configuration of a capping unit and a wiping unit; FIG. 1 is a diagram for explaining a wiping operation in a wiping unit; FIG. 2 is a diagram showing a schematic configuration of an example of a cap portion; A block diagram showing the configuration of a control system of an inkjet printing apparatus.

The following describes in detail an inkjet printing device using one embodiment of the liquid ejection device of the present invention with reference to the drawings. The inkjet printing device of this embodiment is characterized by the configuration of the liquid ejection device, but first, the configuration of the entire inkjet printing device will be described. Fig. 1 is a schematic diagram of the inkjet printing device 1 of this embodiment. Fig. 2 is a view of the inkjet printing device 1 shown in Fig. 1 as seen from the direction of arrow A. In the following description of the embodiment, the up, down, left, right, front, back, and rear indicated by the arrows in Fig. 1 are the up, down, left, right, front, and rear directions of the inkjet printing device 1.

As shown in FIG. 1, the inkjet printing device 1 of this embodiment includes a base 2, a foot stand 3, a platen 4, a rail section 5, a head unit 10, and a maintenance unit 20.

The bases 2 are columnar members extending in the front-rear direction and arranged in parallel with a gap in the left-right direction. Two wheels 2a are provided on the bottom surface of each of the two bases 2.

A stand 3 is erected on each base 2. A platen 4 is supported on the upper surfaces of the two opposing stand 3.

Front paper guide 4a and rear paper guide 4b are formed in an arc shape and extend from the front and rear of platen 4. In addition, as shown in FIG. 2, a vacuum chamber 4c in which a fan 4d is installed is provided below platen 4. Note that the vacuum chamber 4c is not shown in FIG. 1.

When the fan 4d in the vacuum chamber 4c rotates, negative pressure is created inside the vacuum chamber 4c, and suction force is generated in the suction holes (not shown) formed in the platen 4. The suction force generated in the suction holes of the platen 4 causes the printing paper P to be attracted to the platen 4.

As shown in FIG. 2, a drive roller 6 and a pressure roller 7 are provided behind the platen 4, facing each other. Note that the drive roller 6 and the pressure roller 7 are omitted from FIG. 1.

The drive roller 6 is a long roller extending in the extension direction of the platen 4, and is rotated by the transport drive motor 61 (see FIG. 7), which will be described later.

The pressure roller 7, like the drive roller 6, is an elongated roller that extends in the extension direction of the platen 4 and is supported so that it can be raised and lowered by a lifting mechanism not shown.

The printing paper P on the rear paper guide 4b is then clamped between the drive roller 6 and the pressure roller 7, and as the drive roller 6 rotates while the pressure roller 7 presses the printing paper P, the printing paper P is sent forward.

A take-up side core holder 8 is provided on the front side of the base 2 of the inkjet printing device 1, which detachably holds the core 8a around which the printing paper P is wound. The take-up side core holder 8 is connected to a take-up drive motor 81 (see FIG. 7) via a torque limiter (not shown), and is configured so that the take-up side core holder 8 is rotated by the take-up drive motor 81.

A supply-side core holder 9 is provided on the rear side of the base 2 of the inkjet printing device 1, which detachably holds a core 9a of rolled paper on which printing paper P is wound in a roll shape. The supply-side core holder 9 is connected to a supply drive motor 91 (see FIG. 7) via a torque limiter (not shown), and is configured so that the supply-side core holder 9 is rotated by the supply drive motor 91.

As shown in FIG. 2, the roll paper (print paper P) held by the supply-side core holder 9 is pulled out and passes through the rear paper guide 4b, between the drive roller 6 and pressure roller 7, over the platen 4, and the front paper guide 4a, before being wound onto the core 8a held by the winding-side core holder 8.

A rail section 5 is mounted on the top of the two legs 3 via a support member (not shown). The rail section 5 includes a rail (not shown) extending in the left-right direction and a main scanning drive motor 54 (see FIG. 7) that moves the head unit 10 back and forth in the left-right direction on the rail.

A maintenance unit 20 is provided at one end of the rail portion 5. A wiping unit 30 and a capping unit 40, which will be described later, are provided within the maintenance unit 20. The head unit 10 is then placed within the maintenance unit 20, whereby wiping by the wiping unit 30 and capping by the capping unit 40 are performed. In this embodiment, the maintenance unit 20 includes a configuration that corresponds to the liquid discharge device of the present invention.

Then, extending from the maintenance unit 20 are a common flow path 52 (described later) through which cleaning liquid containing a pretreatment liquid is discharged, and a common flow path 53 (described later) through which cleaning liquid containing ink is discharged. A waste liquid tank 50 is provided at the end of the common flow path 52, and a waste liquid tank 51 is provided at the end of the common flow path 53.

The waste liquid tank 50 and the waste liquid tank 51 are installed near the base 2 below the maintenance unit 20.

Figure 3 is a diagram showing the schematic configuration of the head unit 10. As shown in Figure 3, the head unit 10 of this embodiment is provided with five heads, namely, the first head 11 to the fifth head 15. The second head 12, the third head 13, and the fourth head 14 are inkjet heads that eject ink of different colors, for example, C (cyan), M (magenta), and Y (yellow) ink.

The fifth head 15 has a similar configuration to the second head 12 to the fourth head 14, but ejects a pretreatment liquid instead of ink. The pretreatment liquid is a liquid that is applied for pretreatment before ink is ejected onto the printing paper P to perform the printing process. As the pretreatment liquid, for example, a liquid that improves the color development and uniform application of the ink is used, but a pretreatment liquid that is already known can be used. In this embodiment, the fifth head 15 corresponds to the treatment liquid head of the present invention.

The first head 11 is an inkjet head that ejects ink in the same way as the second to fourth heads 12 to 14. For example, when printing a pattern on a black base, the first head 11 ejects white ink onto the black base so that the black color of the base does not show through.

As shown in FIG. 3, the first to fifth heads 11 to 15 are arranged side by side in the direction of movement of the head unit 10 (left and right direction), but the first head 11 and the second to fourth heads 12 to 14 are staggered, and the fifth head 15 and the second to fourth heads 12 to 14 are also staggered.

That is, the second to fourth heads 12 to 14 and the first and fifth heads 11, 15 are arranged at different positions in a direction (front-to-back direction) perpendicular to the movement direction of the head unit 10. The first head 11 and the fifth head 15 are arranged at the same position in a direction (front-to-back direction) perpendicular to the movement direction of the head unit 10. The second to fourth heads 12 to 14 are also arranged at the same position in a direction (front-to-back direction) perpendicular to the movement direction of the head unit 10.

Next, the maintenance unit 20 of this embodiment will be described. Figure 4 is a diagram showing the general configuration of the maintenance unit 20 of this embodiment.

As shown in FIG. 4, the maintenance unit 20 is provided with a wiping unit 30 and a capping unit 40. Note that the wiping unit 30 in this embodiment corresponds to the wiping section of the present invention, and the capping unit 40 corresponds to the capping section of the present invention.

The wiping unit 30 and the capping unit 40 are arranged side by side in the movement direction (left and right direction) of the head unit 10. In this embodiment, the wiping unit 30 and the capping unit 40 are arranged in this order from the inkjet printing device 1 main body side, but they may be arranged in the opposite order.

The wiping unit 30 includes a cleaning liquid tank 30a, first to fifth wipers 31a to 31e, first and second belt conveyor rollers 33, 34, and first and second conveyor belts 32, 35.

The first to fourth wipers 31a to 31d correspond to the first to fourth heads 11 to 14, and wipe the ejection surfaces of the first to fourth heads 11 to 14. The ejection surface is the surface on which the ink ejection openings of the nozzles of the inkjet head are arranged.

The fifth wiper 31e is a wiper that corresponds to the fifth head 15 and wipes the ejection surface of the fifth head 15.

The first to fifth wipers 31a to 31e are arranged at intervals equal to the intervals between the first to fifth heads 11 to 15 in the movement direction of the head unit 10.

The first to fourth wipers 31a to 31d are erected at the same positions in the front-to-rear direction on the first conveyor belt 32. The fifth wiper 31e is erected on the second conveyor belt 35.

The first to fifth wipers 31a to 31e are made of flexible rubber or similar material.

The cleaning liquid tank 30a stores the cleaning liquid. The cleaning liquid tank 30a has two recesses, a first cleaning liquid tank 30c and a second cleaning liquid tank 30d, and a partition wall 30b is provided between the first cleaning liquid tank 30c and the second cleaning liquid tank 30d. In other words, the first cleaning liquid tank 30c and the second cleaning liquid tank 30d are formed as completely independent cleaning liquid tanks.

The cleaning liquid has the function of dissolving ink. For example, an aqueous solvent containing water and a surfactant can be used as the cleaning liquid.

Examples of surfactants that can be used include anionic surfactants such as sodium fatty acid, sodium alkylbenzenesulfonate, sodium alkylsulfonate, sodium α-olefinsulfonate, sodium alkyl sulfate, sodium alkyl ether sulfate, sodium α-sulfofatty acid ester, and sodium alkyl phosphate; cationic surfactants such as alkyltrimethylammonium and dialkyldimethylammonium; nonionic surfactants such as sorbitan fatty acid ester, polyoxyethylene sorbitan fatty acid ester, sucrose fatty acid ester, polyoxyethylene alkyl ether, and polyoxyethylene alkylphenyl ether; and amphoteric surfactants such as sodium alkylamino fatty acid, alkyl betaine, and alkylamine oxide. Polymer surfactants, silicone surfactants, fluorine surfactants, and acetylene glycol surfactants can also be used. Among these, it is preferable to use polyoxyethylene alkyl ether, and it is more preferable that the HLB value is 11 to 17, the number of carbon atoms in the alkyl group is 8 to 15, and the number of moles of ethylene oxide added is 6 to 25.

It is preferable that the cleaning solution further contains a thickener. As the thickener, a water-soluble polymer-based thickener or a clay mineral-based thickener can be used. As the water-soluble polymer-based thickener, a natural polymer, a semi-synthetic polymer, or a synthetic polymer can be used. As the natural polymer, for example, a plant-based natural polymer such as gum arabic, carrageenan, guar gum, locust bean gum, pectin, tragacanth gum, corn starch, konjac mannan, agar, etc.; a microbial natural polymer such as pullulan, xanthan gum, dextrin, etc.; an animal-based natural polymer such as gelatin, casein, or glue can be used. As the semi-synthetic polymer, for example, a cellulose-based semi-synthetic polymer such as ethyl cellulose, carboxymethyl cellulose, hydroxyethyl cellulose, hydroxypropyl cellulose, methyl cellulose, or hydroxypropyl methyl cellulose can be used; a starch-based semi-synthetic polymer such as hydroxyethyl starch, sodium carboxymethyl starch, or cyclodextrin; an alginic acid-based semi-synthetic polymer such as sodium alginate or propylene glycol alginate; or sodium hyaluronate can be used. Examples of synthetic polymers that can be used include vinyl synthetic polymers such as polyvinylpyrrolidone, polyvinyl alcohol, polyvinyl methyl ether, poly N-vinylacetamide, and polyacrylamide; polyethylene oxide, polyethyleneimine, and polyurethane. Examples of clay mineral thickeners that can be used include smectite clay minerals such as montmorillonite, hectorite, and saponite. Of these, it is preferable to use hydroxypropyl methylcellulose.

In addition to the above components, the cleaning solution may optionally contain water-soluble organic solvents, pH adjusters, antioxidants, preservatives, etc. The viscosity of the cleaning solution at 23°C is preferably 5 to 200 mPa·s, and more preferably 10 to 100 mPa·s.

The first cleaning liquid tank 30c contains a first conveyor belt 32 with first to fourth wipers 31a to 31d standing on it, and the second cleaning liquid tank 30d contains a second conveyor belt 35 with a fifth wiper 31e standing on it.

In addition, first and second belt conveyor rollers 33, 34 are provided in the first cleaning liquid tank 30c and the second cleaning liquid tank 30d. The first and second belt conveyor rollers 33, 34 extend in the left-right direction across the first cleaning liquid tank 30c and the second cleaning liquid tank 30d.

The first and second belt conveyor rollers 33, 34 are arranged in parallel with a gap of at least the length of the head unit 10 in the front-to-rear direction, and the first conveyor belt 32 and the second conveyor belt 35 are stretched between the first belt conveyor roller 33 and the second belt conveyor roller 34.

As shown in FIG. 5, the first and second conveyor belts 32, 35 move as the first belt conveyor roller 33 and the second belt conveyor roller 34 rotate by the belt drive motor 39 (see FIG. 7). This causes the first to fifth wipers 31a to 31e to move in the front-to-back direction (the direction in which the nozzles of the first to fifth heads 11 to 15 are arranged) to wipe the ejection surfaces of the first to fifth heads 11 to 15.

Note that while Figure 5 shows only the first wiper 31a wiping the first head 11 as a representative example, the second to fifth wipers 31b to 31e wiping the second to fifth heads 11 to 15 are similar. Also, L in Figure 5 is cleaning liquid, and cleaning liquid L is stored up to the lower half of the first and second conveyor belts 32, 35 as shown in Figure 5.

Returning to FIG. 4, the first cleaning liquid tank 30c is connected to the first wiper-side flow path 38, and the second cleaning liquid tank 30d is connected to the second wiper-side flow path 37.

A first pump P1 is provided in the first wiper-side flow path 38, and a second pump P2 is provided in the second wiper-side flow path 37.

The first pump P1 provided in the first wiper-side flow path 38 is operated to discharge the cleaning liquid stored in the first cleaning liquid tank 30c to the first wiper-side flow path 38. The second pump P2 provided in the second wiper-side flow path 37 is operated to discharge the cleaning liquid stored in the second cleaning liquid tank 30d to the second wiper-side flow path 37. In this embodiment, the first and second pumps P1 and P2 correspond to the discharge unit of the present invention. In addition, the first cleaning liquid tank 30c and the second cleaning liquid tank 30d are each provided with a supply unit (not shown) that supplies cleaning liquid, and when the cleaning liquid is discharged from the first cleaning liquid tank 30c and the second cleaning liquid tank 30d as described above, new cleaning liquid is supplied by the supply unit. The timing of discharging the cleaning liquid from the first cleaning liquid tank 30c and the second cleaning liquid tank 30d will be described in detail later.

Next, the capping unit 40 will be described. The capping unit 40 seals the ejection surfaces (ejection ports) of the first to fifth heads 11 to 15 to prevent them from drying out while the inkjet printing device 1 is on standby and not performing a printing process.

The capping unit 40 specifically comprises first to fifth cap parts 41 to 45.

The first to fifth cap parts 41 to 45 are cap parts corresponding to the first to fifth heads 11 to 15, and are provided on the plate material 40a at positions corresponding to the first to fifth heads 11 to 15.

Figure 6 is a diagram showing the configuration of the first cap part 41. The first cap part 41 has a base 41a and a capping member 41b formed on the base 41a. The capping member 41b has a bottom part 41c and a peripheral wall 41d erected on the periphery of the bottom part 41c. Two discharge holes 41e are formed in the bottom part 41c.

The length of the capping member 41b in the front-rear direction is equal to the length of the first head 11 in the front-rear direction. The peripheral wall 41d of the capping member 41b is formed from a resin such as rubber, and abuts against and adheres closely to the first head 11, thereby sealing the ejection surface of the first head 11.

When the first head 11 is purged, the liquid ejected from the first head 11 is received by the capping member 41b and discharged from the discharge hole 41e formed in the bottom 41c.

The second to fifth cap parts 42 to 45 have the same configuration and function as the first cap part 41.

The lower surface of the plate material 40a (the surface opposite to the surface on which the first to fifth cap parts 41 to 45 are provided) is provided with a discharge path section 46. The discharge path section 46 is provided in each of the first to fifth cap parts 41 to 45.

The first cap side flow path 47 is connected to the discharge path section 46 corresponding to the first cap section 41, and discharge flow paths (not shown) connected to the first cap side flow path 47 are connected to the discharge path sections 46 (not shown) corresponding to the second to fourth cap sections 42 to 44. The three discharge flow paths (not shown) are connected to the first cap side flow path 47 upstream of the third pump P3. In other words, upstream of the third pump P3, the first cap side flow path 47 and the three discharge flow paths (not shown) are connected in a four-way branch.

Therefore, the ink discharged into the discharge flow path (not shown) connected to the discharge path portion 46 (not shown) corresponding to the second to fourth cap portions 42 to 44 merges with the ink discharged into the first cap side flow path 47 connected to the discharge path portion 46 corresponding to the first cap portion 41 and flows into the third pump P3.

On the other hand, the second cap side flow path 48 is connected to the discharge path portion 46 corresponding to the fifth cap portion 45. The first cap side path 47 and the three discharge paths connected thereto are not connected to the second cap side flow path 47, and are independent of each other. Then, the pretreatment liquid is discharged from the discharge path portion 46 corresponding to the fifth cap portion 45 to the second cap side flow path 48.

Then, by operating the third pump P3 provided in the first cap side flow path 47, the ink received in the first to fourth cap parts 41 to 44 by purging is discharged to the first cap side flow path 47 via the discharge hole 41e and the discharge path part 46.

The first wiper-side flow path 38 described above is connected to the first cap-side flow path 47 near the downstream side of the third pump P3, thereby forming a first junction S1. The same flow path 53 is formed from the first junction S1. As a result, the cleaning liquid discharged from the first cleaning liquid tank 30c flows out to the same flow path 53 via the first wiper-side flow path 38 and the first junction S1.

This allows the cleaning liquid to flow from the first junction S1 to the same flow path 53, so that the ink discharged into the first cap side flow path 47 and adhering to the same flow path 53 can be flushed out by the cleaning liquid. This prevents the ink ejected by purging from solidifying and clogging the same flow path 53.

The cleaning liquid containing the ink that flows into the same flow path 53 is discharged into a waste liquid tank 51 connected to the tip of the same flow path 53.

A fourth pump P4 is provided in the second cap side flow path 48. When the fourth pump P4 is operated, the pretreatment liquid received in the fifth cap portion 45 by purging is discharged to the second cap side flow path 48 via the discharge hole 41e and the discharge path portion 46.

The second cap-side flow path 48 is connected to the second wiper-side flow path 37 described above near the downstream side of the fourth pump P4, thereby forming a second junction S2. The same flow path 52 is formed from the second junction S2. As a result, the cleaning liquid discharged from the second cleaning liquid tank 30d flows out to the same flow path 52 via the second wiper-side flow path 37 and the second junction S2.

This allows the cleaning liquid to flow from the second junction S2 into the same flow path 52, so that the pretreatment liquid discharged into the second cap side flow path 48 and adhering to the same flow path 52 can be flushed out by the cleaning liquid. This prevents the pretreatment liquid discharged by purging from solidifying and clogging the same flow path 52.

The cleaning liquid containing the pretreatment liquid that flows into the same flow path 52 is discharged into a waste liquid tank 50 connected to the tip of the same flow path 52.

In this embodiment, the same flow path 53 is set to be longer than the length of the first wiper side flow path 38 (the length from the connection point of the first wiper side flow path 38 to the first cleaning liquid tank 30c to the first junction point S1) and the length of the first cap side flow path 47 (the length from the connection point of the first cap side flow path 47 to the discharge path portion 46 corresponding to the first cap portion 41 to the first junction point S1).

The same flow path 52 is set to be longer than the length of the second wiper side flow path 37 (the length from the connection point of the second wiper side flow path 37 to the second cleaning liquid tank 30d to the second junction point S2) and the length of the second cap side flow path 48 (the length from the connection point of the second cap side flow path 48 to the discharge path portion 46 corresponding to the fifth cap portion 45 to the second junction point S2).

By setting the length of the same flow paths 52 and 53 as described above, clogging due to ink or pretreatment liquid can be more effectively prevented.

In addition, in this embodiment, as described above, the first cap side flow path 47 from which ink is discharged and the first wiper side flow path 38 from which cleaning liquid containing ink is discharged are merged at a first merging point S1 to form the same flow path 53, and the second cap side flow path 48 from which pretreatment liquid is discharged and the second wiper side flow path 37 from which cleaning liquid containing pretreatment liquid is discharged are merged at a second merging point S2 to form the same flow path 52.

In other words, the ink and the pretreatment liquid are prevented from mixing in the flow path. This prevents the ink from solidifying due to the ink and pretreatment liquid mixing, which can cause the flow path to become clogged.

Figure 7 is a block diagram showing the configuration of a control system of the inkjet printing device 1 of this embodiment. The inkjet printing device 1 operates each of the controlled parts shown in Figure 7 in response to a control signal from the print control device 16. In this embodiment, the print control device 16 corresponds to the control unit of the present invention.

The print control device 16 and the inkjet printing device 1 are connected by a communication line such as a LAN (Local Area Network) or an Internet line, and are configured to be able to communicate with each other. The communication line may be wired or wireless.

The print control device 16 is composed of a computer equipped with a CPU (Central Processing Unit), semiconductor memory, a hard disk, etc. Based on an input print job, the print control device 16 executes a print control program stored in advance in a storage medium such as a semiconductor memory or a hard disk, and controls each part shown in FIG. 7 by operating an electric circuit.

The print control device 16 also controls the first and second pumps P1 and P2 to control the discharge of cleaning liquid from the first and second cleaning liquid tanks 30c and 30d. The print control device 16 also controls the discharge of ink from the first to fourth cap units 41 to 44 by controlling the third pump P3, and controls the discharge of pre-treatment liquid from the fifth cap unit 45 by controlling the fourth pump P4.

Furthermore, the print control device 16 controls the first and second pumps P1, P2 to control the timing of draining the cleaning liquid from the first and second cleaning liquid tanks 30c, 30d depending on the amount of liquid discharged from the first to fifth heads 11-15 to the first to fifth cap sections 41-45. Specifically, the print control device 16 controls the first and second pumps P1, P2 to drain the cleaning liquid from the first and second cleaning liquid tanks 30c, 30d each time the number of purgings of the first to fifth heads 11-15 reaches a preset threshold number of times.

This allows the cleaning liquid to flow effectively and efficiently through the same flow path 52 and the same flow path 53, and appropriately prevents clogging of these paths. It also prevents unnecessary discharge of cleaning liquid.

Next, the printing operation of the inkjet printing device 1 of this embodiment will be described. Note that, here, the first head 11 is not used, and the pretreatment liquid is ejected from the fifth head 15 to apply it to the printing paper P, and then ink is ejected from the second to fourth heads 12 to 14 to print on the printing paper P to which the pretreatment liquid has been applied.

First, as shown in FIG. 2, a roll of paper is placed on the supply-side core holder 9, and the roll of paper (print paper P) is pulled out and passed through the rear paper guide 4b, between the drive roller 6 and pressure roller 7, over the platen 4, and the front paper guide 4a, before being wound around the core 8a held by the take-up-side core holder 8.

The print control device 16 then rotates the supply side core holding unit 9, the take-up side core holding unit 8, and the drive roller 6 to feed the print paper P, and stops feeding the print paper P when it reaches the initial printing position.

The print control device 16 then operates the main scanning drive motor 54 to move the head unit 10 in a first direction (either left or right) on the rail section 5. As the head unit 10 moves, the print control device 16 then operates the fifth head 15 of the head unit 10 to apply pretreatment liquid to the first scan line. Note that when scanning the first scan line, ink is not ejected from the second to fourth heads 12 to 14.

Next, the print control device 16 advances the print paper P by one scan line so that the first scan line to which the pretreatment liquid is applied is positioned directly below the second to fourth heads 12 to 14.

Then, the print control device 16 moves the head unit 10 on the rail section 5 in a second direction opposite to the first direction, and, as the head unit 10 moves, ejects ink from the second to fourth heads 12 to 14 to print the first scan line. The print control device 16 also prints the first scan line and operates the fifth head 15 to apply pretreatment liquid to the second scan line that follows the first scan line.

The print control device 16 then advances the print paper P by one scan line, positions the second scan line directly below the second to fourth heads 12 to 14, and positions the third scan line, which is the next to the second scan line, directly below the fifth head 15.

The print control device 16 then moves the head unit 10 on the rail section 5 in the first direction, and in conjunction with this movement, operates the second to fourth heads 12 to 14 and the fifth head 15 to apply pretreatment liquid to the third scan line and print on the second scan line.

Then, the print control device 16, in the same manner as described above, alternates between feeding out one scan line of print paper P and moving the head unit 10 on the rail section 5 in the first direction or the second direction, sequentially applying pretreatment liquid to the (n+1)th scan line and printing on the nth scan line.

In the above explanation, the operation is described when the pretreatment liquid is applied by the fifth head 15 without using the first head 11, but the base may be printed using the first head 11 without using the fifth head 15. In this case, the ink ejection timing from the first head 11 is the same as the ejection timing of the fifth head 15 in the above explanation.

Next, we will explain the maintenance operation of the inkjet printing device 1 of this embodiment.

The maintenance operation is performed during a standby period when no printing process is being performed, and at this time, the head unit 10 is placed in the maintenance unit 20 shown in Figure 1.

First, with the head unit 10 positioned above the capping unit 40, the head unit 10 is controlled to eject ink at a predetermined pressure, thereby performing purging.

During this purging, the ejection surfaces of the first to fifth heads 11 to 15 of the head unit 10 may be sealed by the first to fifth cap parts 41 to 45 of the capping unit 40, or may be open. However, it is preferable to seal them by the first to fifth cap parts 41 to 45, as sealing them in this way can prevent dust and other debris from entering the first to fifth cap parts 41 to 45 and the surroundings of the first to fifth cap parts 41 to 45 from being contaminated by ink.

The ink ejected from the first to fourth heads 11 to 14 by the above-mentioned purging is received by the first to fourth cap units 41 to 44, and is discharged into the first cap side flow path 47 by the operation of the third pump P3, and is discharged into the waste liquid tank 51 via the same flow path 53. Ink ejected from the fifth head 15 by the above-mentioned purging is received by the fifth cap unit 45, and is discharged into the second cap side flow path 48 by the operation of the fourth pump P4, and is discharged into the waste liquid tank 50 via the same flow path 52.

After the above-mentioned purging is completed, the print control device 16 moves the head unit 10 on the rail section 5 and positions it above the wiping unit 30.

Then, the print control device 16 moves the first to fifth wipers 31a to 31e, which are immersed in the cleaning liquid in the first and second cleaning liquid tanks 30c and 30d, using the first and second conveyor belts 32 and 35, and positions the tips of the first to fifth wipers 31a to 31e at the front ends of the corresponding first to fifth heads 11 to 15.

The print control device 16 then moves the first to fifth wipers 11 to 15 in this state so that the tips of the first to fifth wipers 31a to 31e are pressed against the ejection surfaces of the first to fifth heads 11 to 15 and are elastically deformed. At this time, the print control device 16 may move the head unit 10 downward or move the wiping unit 30 upward in order to press the tips of the first to fifth wipers 31a to 31e against the ejection surfaces of the first to fifth heads 11 to 15.

Then, while the tips of the first to fifth wipers 31a to 31e are pressed against the ejection surfaces of the first to fifth heads 11 to 15, the print control device 16 further moves the first to fifth wipers 31a to 31e, thereby wiping the ejection surfaces of the first to fifth heads 11 to 15.

Then, the print control device 16 ends wiping by moving the tips of the first to fifth wipers 31a to 31e to the rear ends of the first to fifth heads 11 to 15, and then moves the first to fifth wipers 31a to 31e further, so that they are again immersed in the cleaning liquid in the first cleaning liquid tank 30c and the second cleaning liquid tank 30d.

After the above-mentioned wiping operation is completed, the print control device 16 moves the head unit 10 and positions it above the capping unit 40. The print control device 16 then raises the capping unit 40 using a lifting mechanism (not shown), causing the first to fifth cap parts 41 to 45 to abut against the first to fifth heads 11 to 15, sealing the ejection surfaces of the first to fifth heads 11 to 15. This concludes the explanation of the maintenance operation of this embodiment.

When performing printing after the above-mentioned maintenance operation, the capping unit 40 descends and the head unit 10 moves left and right along the rail portion 5 to perform printing.

The above-mentioned maintenance operations may be performed automatically immediately before starting the printing process, or in response to user input. They may also be performed at preset intervals or for a preset length of the printing range (amount of print paper P fed out).

Then, as described above, the print control device 16 controls the first and second pumps P1 and P2 to discharge the cleaning liquid from the first and second cleaning liquid tanks 30c and 30d, and to flow the cleaning liquid containing the ink through the same flow path 53 via the first junction S1, and to flow the cleaning liquid containing the pretreatment liquid through the same flow path 52 via the second junction S2, each time the number of purgings due to the maintenance operation reaches a preset threshold number.

In the above embodiment, the cleaning liquid is discharged from the first and second cleaning liquid tanks 30c, 30d each time the number of purging reaches a preset threshold number, but the timing of discharging the cleaning liquid from the first and second cleaning liquid tanks 30c, 30d is not limited to this, and for example, the cleaning liquid may be discharged from the first and second cleaning liquid tanks 30c, 30d each time a preset time has elapsed, or the cleaning liquid may be discharged from the first and second cleaning liquid tanks 30c, 30d in response to a user's instruction input.

The present invention further discloses the following supplementary notes.
(Additional Note)

The liquid discharge device of the present invention can include a capping section having a cap section and a cap-side flow path, and a wiping section having a wiper, a cleaning liquid tank in which a cleaning liquid for cleaning the wiper is stored and which discharges the cleaning liquid into the wiper-side flow path, and a wiper-side flow path.

In the liquid discharge device of the present invention, the discharge section is an inkjet head and a treatment liquid head that discharges a treatment liquid different from ink, the capping section has a cap section and a cap side flow path corresponding to the inkjet head, and a cap section and a cap side flow path corresponding to the treatment liquid head, the wiping section has a wiper, a cleaning liquid tank, and a wiper side flow path corresponding to the inkjet head, and a wiper, a cleaning liquid tank, and a wiper side flow path corresponding to the treatment liquid head, and has a first junction where the cap side flow path and the wiper side flow path corresponding to the inkjet head join, and a common flow path for ink is formed from the first junction, and a second junction where the cap side flow path and the wiper side flow path corresponding to the treatment liquid head join, and a common flow path for treatment liquid is formed from the second junction.

In addition, in the liquid discharge device of the present invention, it is preferable that the same flow path extending from the junction is longer than the cap side flow path and the wiper side flow path.

The liquid discharge device of the present invention can also include a discharge unit that discharges the cleaning liquid from the cleaning liquid tank, and a control unit that controls the discharge unit, and the control unit can control the timing of discharge of the cleaning liquid by controlling the discharge unit according to the amount of liquid discharged from the discharge unit to the cap unit.

The inkjet printing device of the present invention includes the above-mentioned liquid ejection device, and prints by ejecting ink from the ejection section onto a printing medium.

1 Inkjet printing device 2 Base 2a Wheels 3 Foot 4 Platen 4a Front paper guide 4b Rear paper guide 4c Vacuum chamber 4d Fan 5 Rail section 6 Drive roller 7 Pressure roller 8 Take-up side core body holding section 8a Core body 9 Supply side core body holding section 9a Core body 10 Head unit 11-15 First to fifth heads 16 Print control device 20 Maintenance unit 30 Wiping unit 30a Cleaning liquid tank 30b Partition wall 30c First cleaning liquid tank 30d Second cleaning liquid tank 31a-31e First to fifth wipers 32 First conveyor belt 33 First belt conveyor roller 34 Second belt conveyor roller 35 Second conveyor belt 37 Second wiper side flow path 38 First wiper side flow path 39 Belt drive motor 40 Capping unit 40a Plate material 41-45 First to fifth cap parts 41a Base 41b Capping member 41c Bottom 41d Peripheral wall 41e Drain hole 46 Drain path 47 First cap side flow path 48 Second cap side flow path 50 Waste liquid tank 51 Waste liquid tank 54 Main scanning drive motors 52, 53 Same flow path 61 Transport drive motor 81 Winding drive motor 91 Supply drive motor L Cleaning liquid P Printing paper P1 First pump P2 Second pump P3 Third pump P4 Fourth pump S1 First junction S2 Second junction

Claims (5)

a first cap side flow path through which ink is discharged into a first cap portion that seals an ink ejection port of an inkjet head having an ink ejection port for ejecting ink;
a second cap side flow path through which the treatment liquid discharged into a second cap portion that seals a treatment liquid discharge port of a treatment liquid head having a treatment liquid discharge port that discharges a treatment liquid different from ink;
a first wiper-side flow path through which a cleaning liquid used for wiping the ink ejection ports of the inkjet head is discharged from a first cleaning liquid tank that stores the cleaning liquid;
a second wiper-side flow path through which a cleaning liquid used for wiping the processing liquid discharge port of the processing liquid head is discharged from a second cleaning liquid tank in which the cleaning liquid is stored,
A liquid discharge device having a first junction where the first cap side flow path and the first wiper side flow path join, from which a common flow path for ink is formed, and a second junction where the second cap side flow path and the second wiper side flow path join, from which a common flow path for treatment liquid is formed. a capping portion having the first cap portion, the second cap portion, the first cap side flow path, and the second cap side flow path;
2. The liquid discharging device according to claim 1, further comprising a wiping section having the first cleaning liquid tank, the second cleaning liquid tank, the first wiper-side flow path and the second wiper-side flow path. a cap-side flow path through which the discharged liquid is discharged into a cap portion that seals the discharge port of a discharge portion having the discharge port for discharging the liquid;
a wiper-side flow path through which cleaning liquid is discharged from a wiping portion that wipes the discharge port of the discharge portion,
A liquid discharge device having a junction where the cap-side flow path and the wiper-side flow path join together, the junction forming a common flow path,
a liquid discharge device in which the same flow path extending from the junction is longer than the cap side flow path and the wiper side flow path; a cap-side flow path through which the discharged liquid is discharged into a cap portion that seals the discharge port of a discharge portion having the discharge port for discharging the liquid;
a wiper-side flow path through which cleaning liquid is discharged from a wiping portion that wipes the discharge port of the discharge portion,
A liquid discharge device having a junction where the cap-side flow path and the wiper-side flow path join together, the junction forming a common flow path,
The cleaning device further includes a discharge unit that discharges the cleaning liquid from a cleaning liquid tank that is provided in the wiping unit and in which the cleaning liquid is stored, and a control unit that controls the discharge unit,
The control unit controls the discharge unit in accordance with the amount of liquid discharged from the discharge unit to the cap unit, thereby controlling the timing of discharging the cleaning liquid. An inkjet printing device comprising the liquid ejection device according to any one of claims 1 to 4.