JP7475896B2 - Wiping Device - Google Patents

Description

The present invention relates to a wiping device that wipes the ink ejection surface of a nozzle row of an inkjet head.

Conventionally, inkjet printing devices have been proposed that print by ejecting ink from an inkjet head onto print media such as paper and film. It has also been proposed to use this inkjet printing device to perform printing on base materials such as building materials and decorative panels.

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 blade is used to wipe the ink ejection ports of the nozzles. This allows the wiper blade to remove any ink that has adhered to the ink ejection ports of the nozzles as well as any debris on the ink ejection ports of the nozzles. This also prevents the water repellency of the ink ejection surface from decreasing and the nozzles from drying out.

Here, the wiping action described above can be used to remove dirt from the ink ejection ports, but this also causes the wipe blade to become dirty.

Therefore, Patent Document 1 proposes a method in which the ink-stained wipe blade is brought into contact with a sponge or the like and then immersed in a cleaning tank filled with cleaning liquid.

Patent Document 2 also proposes a method for improving the maintainability of the head maintenance mechanism by using a wet wiping means that moistens the wipe blade.

Patent Document 3 also proposes a method in which the nozzle surface of an inkjet head is wiped with a rotatable wiper blade and then immersed in a cleaning tank.

Patent Document 4 also proposes wiping the nozzle surface of an inkjet head with a wiper blade, and then vibrating the wiper blade after it has moved to an area outside the nozzles to remove any adhering liquid or debris.

Patent No. 4954852 JP 2016-155279 A JP 2008-290313 A JP 2002-79681 A

However, the method described in Patent Document 1 may result in recontamination of the wipe blade due to the ink-contaminated sponge and used cleaning fluid.

In addition, in Patent Document 2, a wipe blade made of a porous material is impregnated with cleaning liquid to perform the wiping operation, but when the porous material becomes wet with the cleaning liquid, deformation and swelling occur, and it is not possible to press the inkjet head evenly, which may result in reduced wiping performance.

In addition, in the method described in Patent Document 3, ink that adheres to the wipe blade during wiping may contaminate the cleaning liquid in the cleaning liquid tank, resulting in re-contamination of the wipe blade.

In addition, simply vibrating the wipe blade, as in the method described in Patent Document 4, is not enough to sufficiently remove ink and other substances adhering to the wipe blade.

In view of the above circumstances, the present invention aims to provide a wiping device that can wipe an inkjet head with a wipe blade that is always wet with clean cleaning liquid.

The wiping device of the present invention includes a wiper blade that wipes the ink ejection surface of a nozzle row of an inkjet head having a nozzle row in which multiple nozzles that eject ink are arranged, a cleaning tank in which cleaning liquid is stored and in which the wiper blade is immersed, and a spraying unit that sprays the cleaning liquid onto the wiper blade.

The wiping device of the present invention is equipped with a cleaning tank in which the wipe blade is immersed, and a spraying section that sprays cleaning liquid onto the wipe blade. This allows the wipe blade to be cleaned with clean cleaning liquid by the spraying section, and the wipe blade after cleaning can be immersed in the cleaning tank, preventing contamination of the cleaning liquid in the cleaning tank. Therefore, the inkjet head can always be wiped with a wipe blade wetted with clean cleaning liquid.

FIG. 1 is a perspective view showing a schematic configuration of an embodiment of an inkjet printing apparatus according to the present invention; FIG. 1 shows a schematic configuration of a shuttle unit. FIG. 2 is a perspective view showing the appearance of an inkjet head; FIG. 4 is a partial cross-sectional view of the inkjet head shown in FIG. 3 taken along line AA. FIG. 1 is a diagram showing a schematic configuration of a capping unit. FIG. 3 is a perspective view showing the appearance of the ink removal unit; FIG. 7 is a left side view of the ink removal unit shown in FIG. FIG. 13 is a diagram for explaining an ink removal operation by an ink removal unit; FIG. 13 is a top view of the absorbing member after the first ink removal operation. FIG. 13 is a top view of the absorbing member after the second ink removal operation. FIG. 13 is a diagram showing an example of a configuration in which two overlapping absorbing members are pressed against the nozzle guard and the ink ejection surface. FIG. 13 is a diagram showing an example of a configuration in which two overlapping absorbing members are pressed against the nozzle guard and the ink ejection surface. A diagram showing the internal structure of the wiping unit. FIG. 13 is a perspective view showing an internal state of the wiping unit in a standby state; FIG. 13 is a perspective view showing the internal state of the wiping unit when the cleaning liquid is sprayed; A diagram showing the position of the wiper blade when wiping the inkjet head. Diagram showing the position of the wipe blade when spraying cleaning fluid Diagram showing wipe blades rotating forward and backward FIG. 13 is a diagram showing another embodiment of the blade fixing member; FIG. 13 is a diagram showing another embodiment of the blade fixing member; FIG. 2 is a block diagram showing a control system of the inkjet printing apparatus shown in FIG. FIG. 2 is a diagram for explaining a cleaning operation of the inkjet printing apparatus shown in FIG. 1; FIG. 2 is a diagram for explaining a cleaning operation of the inkjet printing apparatus shown in FIG. FIG. 13 is a diagram showing an example of the state of ink seeping out from a gap in the nozzle guard when an absorbing member is pressed against the ink.

An inkjet printing device using one embodiment of the wiping device of the present invention will be described in detail below with reference to the drawings. The inkjet printing device of this embodiment is characterized by the wiping operation of the inkjet head, but first, the overall configuration of the inkjet printing device will be described. Figure 1 is a schematic diagram of the inkjet printing device 1 of this embodiment. Note that in the following description of the embodiment, the up, down, left, right, front, back, and rear directions indicated by arrows in Figure 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 shuttle base unit 2, a flatbed unit 3, and a shuttle unit 4.

The shuttle base unit 2 supports the shuttle unit 4 and moves the shuttle unit 4 in the front-rear direction (sub-scanning direction). Specifically, the shuttle base unit 2 includes a stand 11 and a sub-scanning drive motor 12 (see FIG. 18).

The stand 11 is formed in a rectangular frame shape and supports the shuttle unit 4. Sub-scanning drive guides 13A and 13B extending in the front-rear direction are formed on the left and right frames of the stand 11. The sub-scanning drive guides 13A and 13B guide the shuttle unit 4 to move in the front-rear direction. The sub-scanning drive motor 12 moves the shuttle unit 4 in the front-rear direction.

The flatbed unit 3 supports the print medium 15, such as building materials or decorative panels. The flatbed unit 3 is placed in a rectangular recess formed inside the stand portion 11 of the shuttle base unit 2. The flatbed unit 3 has a media placement surface 3a, which is a horizontal surface on which the print medium 15 is placed. The flatbed unit 3 has a lifting mechanism consisting of a hydraulic drive mechanism (not shown) or the like, which is configured to allow the height of the media placement surface 3a to be adjusted.

The shuttle unit 4 performs a printing process on the print medium 15. FIG. 2 is a diagram showing a schematic configuration of the shuttle unit 4. As shown in FIG. 2, the shuttle unit 4 includes a housing 21, a main scanning drive guide 22, a main scanning drive motor 23 (see FIG. 18), a head lift guide 24, a head lift motor 25 (see FIG. 18), a head unit 26, a capping unit 66, a suction unit 28, an ink removal unit 29, and a wiping unit 30.

The housing 21 houses the head unit 26 and other components. The housing 21 is formed in a gate shape that straddles the flatbed unit 3 in the left-right direction. The housing 21 is supported by the stand 11 of the shuttle base unit 2 and is configured to be movable along the sub-scanning drive guides 13A and 13B.

The main scanning drive guide 22 guides the head unit 26 to move in the left-right direction (main scanning direction). The main scanning drive guide 22 is formed of a long member extending in the left-right direction. The head unit 26 moves in the left-right direction by the main scanning drive motor 23.

The head lift guide 24 guides the head unit 26 to move in the vertical direction. The head lift guide 24 is formed from a member that is elongated in the vertical direction. The head lift guide 24 is configured to be movable in the left-right direction along the main scanning drive guide 22 together with the head unit 26. The head unit 26 is raised and lowered in the vertical direction by the head lift motor 25.

The head unit 26 performs printing by ejecting ink onto the print medium 15 while moving left and right along the main scanning drive guide 22 as described above. As shown in FIG. 2, the head unit 26 has four inkjet heads 31. Note that the number of inkjet heads 31 is not limited to four, and for example, five or more inkjet heads 31 may be provided in the head unit 26.

Figure 3 is a perspective view showing the appearance of the inkjet head 31, and Figure 4 is a diagram showing a portion of the cross section of the inkjet head 31 shown in Figure 3 taken along line A-A.

As shown in FIG. 3, the inkjet head 31 includes a nozzle plate 36 and a nozzle guard 32. The nozzle plate 36 has a nozzle row in which ink ejection ports 37 for ejecting ink are arranged in the front-rear direction.

As shown in Figures 3 and 4, the nozzle guard 32 has an opening 46 in a portion of the nozzle plate 36 that corresponds to the nozzle row, and is provided with a gap 40 between the nozzle guard 32 and the ink ejection surface 36a of the nozzle row. In this embodiment, the ink ejection surface 36a is the surface on which the openings of the ink ejection ports 37 of the nozzles are arranged, and is the same surface as the surface of the nozzle plate 36.

The nozzle guard 32 protects the ink ejection surface 36a of the nozzle plate 36. Specifically, the nozzle guard 32 has a bottom plate 41 formed to cover the periphery of the nozzle row, and a side wall 42 erected on the periphery of the bottom plate 41. The bottom plate 41 has the above-mentioned opening 46 formed therein, and a gap 40 is formed between the bottom plate 41 and the ink ejection surface 36a. The opening 46 is formed in a rectangular shape that is elongated in the front-rear direction, and is formed so that the ink ejection ports 37 of all the nozzles are exposed. In addition, the gap 40 is formed by the space sandwiched between the bottom plate 41 of the nozzle guard 32 and the periphery of the ink ejection surface 36a facing the bottom plate 41 when the nozzle guard 32 is attached to the nozzle plate 36.

Returning to FIG. 2, the four inkjet heads 31 are arranged in parallel in the left-right direction. Each of the four inkjet heads 31 ejects ink of a different color (e.g., cyan, black, magenta, and yellow).

One end of an ink supply pipe 53 is connected to each inkjet head 31. A supply pump 55 (see FIG. 18) is disposed in the ink supply pipe 53, and the ink is supplied to the inkjet head 31 via the ink supply pipe 53 by operating the supply pump 55.

The capping unit 66 seals the opening 46 of the nozzle guard 32 to prevent the ink ejection port 37 of the nozzle from drying out while the inkjet printing device 1 is on standby and not performing a printing process.

The capping unit 66 is installed inside the right end of the housing 21 as shown in FIG. 2. When the head unit 26 moves to the standby position at the right end of the housing 21, it seals the opening 46 of the nozzle guard 32.

As shown in FIG. 5, the capping unit 66 includes a cap 71 and a cap base 72. The cap 71 includes an oval bottom 76 and a peripheral wall 77 erected on the periphery of the bottom 76. The bottom 76 is formed with a suction hole 78 for sucking ink ejected from the inkjet head 31 during purging. The suction hole 78 is connected to a suction tube 68 of the suction unit 28, which will be described later. The cap base 72 is the base on which the cap 71 is formed.

The capping unit 66 is raised and lowered in the vertical direction by a cap lifting motor 67 (see FIG. 18). Specifically, the capping unit 66 is raised and lowered between an abutment position where the peripheral wall 77 of the cap 71 abuts against the nozzle guard 32 and a retracted position below the abutment position.

The suction unit 28, which is provided below the capping unit 66, sucks up the ink that has accumulated in the capping unit 66. The suction unit 28 is equipped with four suction tubes 68, four suction pumps 69, and a waste liquid tank 70.

One end of each of the four suction tubes 68 is connected to a suction hole 78 formed in the bottom 76 of each of the four caps 71, and the other end of each of the four suction tubes 68 is connected to a waste liquid tank 70. A suction pump 69 is provided for each of the suction tubes 68.

The ink accumulated in the capping unit 66 flows out of the suction holes 78 of each cap 71 by the suction of the suction pump 69, and is stored in the waste tank 70 via each suction pipe 68.

Returning to FIG. 2, the ink removal unit 29 is installed inside the left end of the housing 21 of the shuttle unit 4. The ink removal unit 29 is a mechanism that removes ink that has entered the gap 40 formed between the bottom plate 41 of the nozzle guard 32 and the ink ejection surface 36a of the inkjet head 31 by pressing an absorbing member 50 that absorbs ink against the nozzle guard 32 and the ink ejection surface 36a of the inkjet head 31.

Figure 6 is a perspective view showing the appearance of the ink removal unit 29. Also, Figure 7 is a view of the ink removal unit 29 shown in Figure 6 as seen from the left side. As shown in Figures 6 and 7, the ink removal unit 29 includes a press table 91, a feed roller 92, a winding roller 93, a feed-side transport roller 94, a winding-side transport roller 95, and a press table lifting mechanism 96.

The feed roller 92, the feed-side transport roller 94, the winding-side transport roller 95, and the winding roller 93 are roller members extending in the left-right direction.

The feed roller 92 is a roller on which the rolled absorbent member R, which is the absorbent member 50 wound in a roll shape, is placed. The feed roller 92 is a roller that sends out the absorbent member 50 unwound from the rolled absorbent member R toward the winding roller 93.

The material of the absorbing member 50 may be any material capable of absorbing ink, but is preferably a porous sheet. Printing paper having pores may be used as the porous sheet.

In addition, it is preferable that the width of the absorbing member 50 in the left-right direction (the direction in which the four inkjet heads 31 are arranged) is at least twice the total width of the left-right direction of all the inkjet heads 31 (four inkjet heads 31 in this embodiment) that the head unit 26 has.

The feed-side conveying roller 94 is provided above the feed roller 92. The absorbing member 50 sent from the feed roller 92 is conveyed horizontally while in contact with the outer periphery of the feed-side conveying roller 94, and is conveyed from the front side to the rear side.

The take-up side transport roller 95 is at the same height as the feed side transport roller 94 and is provided above the take-up roller 93. The absorbing member 50 sent out from the feed side transport roller 94 is handed over to the take-up side transport roller 95 and transported vertically downward while in contact with the outer periphery of the take-up side transport roller 95, thereby being transported downward toward the take-up roller 93.

The winding roller 93 is at the same height as the feed roller 92 and is provided below the winding-side transport roller 95. The winding roller 93 is a roller that winds up the absorbing member 50 transported downward by the winding-side transport roller 95.

The winding roller 93 is a drive roller that is rotated by the winding motor 29a (see FIG. 18), and the feed roller 92, the feed-side transport roller 94, and the winding-side transport roller 95 are driven rollers that rotate due to friction with the absorbing member 50 that is pulled out from the roll absorbing member R by the rotation of the winding roller 93.

A press table 91 and a press table lifting mechanism 96 are provided between the above-mentioned feed-side conveying roller 94 and the wind-up-side conveying roller 95. An absorbing member 50 is stretched between the feed-side conveying roller 94 and the wind-up-side conveying roller 95 with a certain tension, and the press table 91 is installed below the stretched absorbing member 50 with a predetermined distance therebetween.

The pressing table 91 is a table formed in a rectangular parallelepiped shape from a material having a certain degree of rigidity, such as metal. A cushion part 90 is provided on the upper surface of the pressing table 91.

The cushion portion 90 is made of an elastic material, such as a sponge cloth, a silicone sheet, or a rubber sheet.

By providing the cushion portion 90 on the upper surface of the pressing table 91, when the absorbing member 50 is pressed against the nozzle guard 32 and the ink ejection surface 36a of the inkjet head 31, the adhesion of the absorbing member 50 to the nozzle guard 32 and the ink ejection surface 36a can be improved, and ink that has seeped out from the gap 40 between the ink ejection surface 36a and the nozzle guard 32 can be uniformly removed.

A press table lifting mechanism 96 that raises and lowers the press table 91 in the vertical direction is provided below the press table 91. The press table lifting mechanism 96 is driven by a press table lifting motor 29b (see FIG. 18) and is configured to expand and contract in the vertical direction, and this expansion and contraction action raises and lowers the press table 91 in the vertical direction.

Figure 8 is a diagram for explaining the ink removal operation by the ink removal unit 29 described above. First, the head unit 26 is moved above the absorbing member 50 stretched between the feed-side transport roller 94 and the take-up-side transport roller 95. Then, with the four inkjet heads 31 of the head unit 26 positioned above the absorbing member 50 with a gap between them, the inkjet heads 31 are purged. The dotted oval PI in Figure 8A indicates the ink remaining on the ink ejection surface 36a of the inkjet head 31 due to the purging.

After the above-mentioned purging, the press table lifting mechanism 96 extends upward, causing the press table 91 to rise as shown in FIG. 8B. The rise of the press table 91 brings the cushion portion 90 and the absorbing member 50 into contact, and then the press table 91 rises further, causing the absorbing member 50 to be pressed against the nozzle guard 32 with a predetermined pressure, and ink that has entered the gap 40 formed between the bottom plate 41 of the nozzle guard 32 and the ink ejection surface 36a is pushed out toward the opening 46 of the nozzle guard 32. Then, the absorbing member 50 is pressed against the ink ejection surface 36a, causing the ink pushed out of the gap 40 to be absorbed by the absorbing member 50.

After a certain period of time has elapsed with the absorbing member 50 pressed against the nozzle guard 32 and the ink ejection surface 36a, the press table lifting mechanism 96 contracts, causing the press table 91 to lower and move away from the absorbing member 50, as shown in FIG. 8C.

Next, after the pressing table 91 leaves the absorbing member 50, the take-up roller 93 rotates, and a portion of the absorbing member 50 that has absorbed the ink is transported backward. At this time, it is transported by the length of the inkjet head 31 in the direction in which the nozzle row of the inkjet head 31 extends.

Then, as a result of this transport, a new area of the absorbing member 50 that has not absorbed ink is positioned opposite the ink ejection surface 36a of the inkjet head 31.

This eliminates the need to replace the sheet-like absorbent material, reducing the frequency of replacement and improving maintainability.

Here, the four inkjet heads 31 provided on the head unit 26 are arranged at a predetermined interval in the left-right direction. In this embodiment, the distance between the inkjet heads 31 is at least the width in the left-right direction of the inkjet heads 31 (the direction perpendicular to the direction in which the nozzle rows of the inkjet heads 31 extend).

Therefore, the range in which ink is absorbed by the absorbing member 50 by one ink removal operation described above is also a range with a predetermined gap in the left-right direction. Figure 9 is a top view of the absorbing member 50 after the first ink removal operation, and the shaded area in Figure 9 is the range in which ink has been absorbed. As shown in Figure 9, the range in which ink has been absorbed is also arranged at the same intervals as the inkjet head 31. In other words, the absorbing member 50 between the ranges in which ink has been absorbed has not absorbed ink and is in the same state as an unused state.

Therefore, before the absorbing member 50 is transported rearward as shown in FIG. 8C, the absorbing member moving unit 51 (see FIG. 18) may move the ink removing unit 29 in the left-right direction at least a distance equal to the width of the inkjet head 31. The absorbing member moving unit 51 is composed of a known actuator.

As a result, during the next purge, the press table 91 can be raised as shown in FIG. 8B to allow the ink to be absorbed in the unused area of the absorbing member 50, allowing the absorbing member 50 to be used more efficiently. FIG. 10 shows the area where ink has been absorbed by the absorbing member 50 after the second ink removal operation described above.

Then, after the second ink removal operation is performed, the absorbing member 50 can be transported backward as shown in Figure 8C.

The amount of transport of the absorbing member 50 in the forward and backward directions is controlled by the control unit 5 controlling the amount of rotation of the winding motor 29a. However, as the diameter of the roll absorbing member R changes with use, the desired amount of transport may not be achieved even if the winding motor 29a is rotated by a preset amount of rotation.

Therefore, for example, a transport amount detection unit such as a rotary encoder may be provided on at least one of the feed side transport roller 94 and the take-up side transport roller 95 to detect the transport amount of the absorbing member 50, and the control unit 5 may control the rotation amount of the take-up motor 29a based on the detected transport amount, thereby achieving the desired transport amount.

In addition, in this embodiment, as described above, one absorbing member 50 unwound from the roll absorbing member R is pressed against the inkjet head 31, but this is not limited thereto. For example, when a large amount of ink enters the gap 40 of the inkjet head 31, multiple absorbing members 50 may be stacked and pressed against the inkjet head 31. Figures 11 and 12 are diagrams showing an example of a configuration in which two absorbing members 50 are stacked and pressed against the nozzle guard 32 and the ink ejection surface 36a.

In the configuration shown in FIG. 11, the absorbing member 50 unwound from the roll absorbing member R installed on the feed roller 92 is transported from the rear side to the front side toward the bottom of the inkjet head 31. After passing directly below the inkjet head 31, the absorbing member 50 is folded back to the opposite side by the first transport roller 97a and transported again toward the bottom of the inkjet head 31.

The first transport roller 97a is at the same height as the feed roller 92 and is installed on the opposite side of the head unit 26 from the feed roller 92.

The absorbing member 50, which has been folded back by the first transport roller 97a, passes directly below the inkjet head 31 again and is transported to the second transport roller 97b. The second transport roller 97b is disposed diagonally below the front side of the feed roller 92.

The absorbing member 50 transported to the second transport roller 97b is then folded back to the opposite side by the second transport roller 97b and taken up by the take-up roller 93. The take-up roller 93 is disposed diagonally below and in front of the second transport roller 97b.

As described above, the absorbing member 50 that passes directly below the inkjet head 31 is folded back and transported to the opposite side by the first transport roller 97a, so that the absorbing member 50 is transported twice directly below the inkjet head 31. If the pressing table 91 is raised while the absorbing member 50 is being transported in this manner, two sheets of the absorbing member 50 in a stacked state within the range indicated by the dotted oval in FIG. 11 can be pressed against the inkjet head 31. As a result, even if a large amount of ink enters the gap 40 of the inkjet head 31, the ink can be sufficiently absorbed by the two absorbing members 50.

Next, the configuration shown in FIG. 12 is a configuration in which another set of the feed roller 92, feed-side conveying roller 94, take-up side conveying roller 95, and take-up roller 93 of this embodiment is provided below the head unit 26. In the configuration shown in FIG. 12, another set of feed-side conveying rollers 98 and take-up side conveying rollers 99 is provided below the feed-side conveying rollers 94 and take-up side conveying rollers 95 and in a position closer to the pressing table 91. Note that the feed roller 92 and take-up roller 93, as well as another set of rollers similar to these rollers, are not shown in FIG. 12.

Even with the configuration shown in FIG. 12, when the pressing table 91 is raised, the two absorbing members 50 can be pressed against the inkjet head 31 in a stacked state. This allows the ink to be sufficiently absorbed by the two absorbing members 50 even if a large amount of ink enters the gap 40 of the inkjet head 31.

In addition, depending on the amount of ink entering the gap 40 of the inkjet head 31, the control unit 5 may switch between pressing one absorbing member 50 against the nozzle guard 32 and the ink ejection surface 36a and pressing multiple absorbing members 50 against the nozzle guard 32 and the ink ejection surface 36a. Specifically, for example, in the case of the configuration shown in FIG. 12, when the control unit 5 presses one absorbing member 50 against the nozzle guard 32 and the ink ejection surface 36a, the absorbing member 50 of one of the roller pairs may be moved left and right by a predetermined moving mechanism to move it away from directly below the inkjet head.

The absorbing member 50 preferably contains a liquid that dissolves dried ink. By including such a liquid in the absorbing member 50, ink that has seeped out from the gap 40 between the ink ejection surface 36a and the nozzle guard 32 and dried can also be properly removed. As the liquid that dissolves dried ink, it is preferable to use a liquid similar to the cleaning liquid used in the wiping unit 30 described later. The absorbing member 50 may contain the above liquid in advance, or a tank for storing the above liquid may be provided, and a configuration may be further provided in which the absorbing member 50 is immersed in the tank while the absorbing member 50 is transported from the feed roller 92 to the take-up roller 93.

Returning to FIG. 2, the wiping unit 30 is located inside the left end of the housing 21 of the shuttle unit 4, to the left of the ink removal unit 29 described above. FIG. 13 is a diagram showing the internal configuration of the wiping unit 30, and is a cross-sectional view in the direction of the arrows Z-Z shown in FIG. 2. FIG. 14 is a perspective view showing the internal state of the wiping unit 30 in standby mode, which will be described later, and FIG. 15 is a perspective view showing the internal state of the wiping unit 30 when spraying cleaning liquid, which will be described later.

The wiping unit 30 cleans the ink ejection surface 36a of the inkjet head 31 and the lower surface of the nozzle guard 32 by wet wiping. In this embodiment, the wiping unit 30 corresponds to the wiping device of the present invention.

Specifically, as shown in FIG. 13, the wiping unit 30 includes a housing 80, a wiping unit 81, a rotating shaft 82, a cleaning tank 83, a shower unit 84, a piping for the cleaning tank 86, and a piping for the shower unit 87.

The wiping unit 81 wipes the ink ejection surface 36a of the inkjet head 31 and the underside of the nozzle guard 32. Specifically, the wiping unit 81 includes a blade support member 81a, a wiper blade 81b, and a blade fixing member 81c.

The wipe blade 81b is made of a flexible material such as rubber and is formed into a rectangular plate. For example, EPDM (ethylene propylene diene rubber) can be used as the rubber.

The blade support member 81a is made of metal, one end of which is connected to the pivot shaft 82, and the other end of which is connected to one end of the wipe blade 81b.

The blade fixing member 81c is a member for fixing the wipe blade 81b to the blade support member 81a, and is formed from a rectangular metal plate. The blade fixing member 81c has two screw holes 81d (see FIG. 14). By inserting a screw into the screw hole 81d and fitting it into the blade support member 81a, the wipe blade 81b is fixed in a state where it is sandwiched between the blade support member 81a and the blade fixing member 81c.

A wiper section 81 is provided for each inkjet head 31 of the head unit 26. In this embodiment, four wipers 81 are arranged in the left-right direction at intervals equal to the intervals between the four inkjet heads 31. In addition, the wiper blade 81b of the wiper section 81 has a width equal to the left-right width of the inkjet head 31.

The pivot shaft 82 is an axial member that is provided in the extension direction of the wiper blade 81b and extends in the left-right direction, and is rotated in the circumferential direction around its central axis by the wiper drive unit 100 (see FIG. 18). One end of the blade support member 81a of each of the four wiper units 81 described above is connected to and supported by the pivot shaft 82. When the pivot shaft 82 rotates, the blade support unit 81a rotates in the direction of arrow A in FIG. 13 and in the opposite direction around the supported one end, i.e., the pivot shaft 82, and the wiper blade 81b also rotates in the same manner.

Figure 13 shows the position of the wipe blade 81b when on standby, Figure 16 shows the position of the wipe blade 81b when wiping the inkjet head 31, and Figure 17 shows the position of the wipe blade 81b when spraying cleaning liquid. The wipe blade 81b is configured to be able to rotate from the position shown in Figure 13 via the position shown in Figure 16 to the position shown in Figure 17, and conversely, to the position shown in Figure 17 via the position shown in Figure 16 to the position shown in Figure 13.

The state shown in FIG. 13 corresponds to the state in which the wipe blade of the present invention is immersed in the cleaning tank, the state shown in FIG. 16 corresponds to the state in which the other end of the wipe blade of the present invention is brought into contact with the ink ejection surface to perform wiping, and the state shown in FIG. 17 corresponds to the state in which cleaning liquid is sprayed by the spraying unit. As described above, the control unit 5 transitions between the state shown in FIG. 13, the state shown in FIG. 16, and the state shown in FIG. 17. Also, the rotating shaft 82 and wiper driving unit 100 in this embodiment correspond to the rotating driving unit of the present invention.

In the wiping unit 30 of this embodiment, the wiper blade 81b is rotated around the rotation axis 82 as described above to transition between the three states. This allows the wiper blade 81b to transition between the three states with a more compact configuration, which allows for a more compact device.

In this embodiment, a more compact configuration is achieved by rotating the wiper blade 81b as described above, but the configuration for transitioning between the three states described above is not limited to a configuration for rotating the wiper blade 81b by the rotating shaft 82, and the three states may be transitioned between by other configurations that combine horizontal movement, vertical movement, and rotation of the wiper blade 81b.

The cleaning tank 83 is installed in the space in the front half of the housing 80 of the wiping unit 30. The cleaning tank 83 is a rectangular parallelepiped container that stores cleaning liquid. The cleaning tank 83 is positioned so that it is immersed in the cleaning liquid when the wipe blade 81b is in the position shown in Figures 13 and 14 (a position extending diagonally forward from a vertical downward position). A cleaning tank piping 86 is connected to the bottom of the cleaning tank 83, and this cleaning tank piping 86 is configured to allow the cleaning liquid to be discharged.

Although not shown, a cleaning liquid supply pipe is connected to the cleaning tank 83 to supply new cleaning liquid into the cleaning tank 83. For example, when the cleaning liquid stored in the cleaning tank 83 decreases due to use or evaporation, the control unit 5 may automatically supply new cleaning liquid to the cleaning tank 83 via the cleaning liquid supply pipe. To control the amount of cleaning liquid, for example, the amount of cleaning liquid stored in the cleaning tank 83 may be detected by a liquid amount detection unit such as an optical sensor, and the control unit 5 may control the amount of cleaning liquid to be maintained at a desired amount based on the detection signal.

The shower unit 84 is installed in the space in the rear half of the housing 80 of the wiping unit 30. The shower unit 84 sprays cleaning liquid when the wipe blade 81b is in the position shown in Figures 15 and 17 (a position extending diagonally rearward from a vertical downward position). The shower unit 84 is positioned so that the sprayed cleaning liquid is sprayed onto the underside of the wipe blade 81b. In this embodiment, the shower unit 84 corresponds to the spray unit of the present invention.

As shown in FIG. 15, the shower unit 84 is composed of a pipe-shaped member extending in the left-right direction, and multiple spray ports 84a are formed along the length of the pipe-shaped member. Cleaning liquid is supplied to the inside of the pipe-shaped member of the shower unit 84 at a predetermined pressure, causing the cleaning liquid to be sprayed in a shower-like manner from the spray ports 84a. The cleaning liquid sprayed from the spray ports 84a is sprayed onto the underside of the wipe blade 81b in the position shown in FIG. 15 and FIG. 17, thereby cleaning the underside of the wipe blade 81b.

The rear half of the inside of the housing 80 has an inclined surface 85 formed at the bottom, with the rear side being higher and the front side being lower. This allows the cleaning liquid that falls after being sprayed from the shower unit 84 onto the wiper blade 81b to flow along the inclined surface 85 and reach the center of the entire bottom of the housing 80. A shower unit pipe 87 is connected to the center of the entire bottom of the housing 80. The cleaning liquid that flows to the center via the inclined surface 85 is then discharged to the outside from the shower unit pipe 87.

In addition, a plate member 88 is provided in front of the shower unit 84 along the outer wall surface at the rear of the cleaning tank 83. The plate member 88 is extended above the outer wall surface at the rear of the cleaning tank 83, and the extended portion is formed so as to be inclined toward the shower unit 84 rather than vertically upward. This prevents the cleaning liquid sprayed from the shower unit 84 onto the underside of the wipe blade 81b, which splashes off the underside of the wipe blade 81b, from splashing around by hitting the underside of the extended portion of the plate member 88. The cleaning liquid that hits the plate member 88 flows downward along the plate member 88 and is discharged from the above-mentioned shower unit piping 87 provided directly below the plate member 88.

The above-mentioned cleaning pipe 86 and shower pipe 87 are both made of elastic tubes and are connected to the downstream side with sufficient length to follow the movement of the wiping unit 30.

Furthermore, as shown in Figs. 14 and 15, four rectangular holes 80a extending in the front-rear direction are formed on the top surface of the housing 80 of the wiping unit 30. The four holes 80a are formed at positions corresponding to the four wiper blades 81b. When the wiper blades 81b move to the wiping position shown in Fig. 16, each wiper blade 81b passes through each corresponding hole 80a. As shown in Fig. 16, the tip end of each wiper blade 81b (the end not connected to the blade support member 81a) is configured to protrude from the top surface of the housing 80.

Next, the wiping operation of the wiping unit 30 in this embodiment will be described.

First, when the shuttle unit 4 is placed in the standby position, the wiping unit 30 waits in the state shown in FIG. 13 in front of the inkjet head 31 (standby position).

When the head unit 26 moves above the wiping section 30, the head lift motor 25 lowers each inkjet head 31, and the distance between the wiping section 30 and each inkjet head 31 approaches a predetermined distance.

Then, the wiper blade 81b, which is immersed in the cleaning liquid in the cleaning tank 83 as shown in FIG. 13, is rotated in the direction of arrow A by the wiper drive unit 100 and moves to the spraying position shown in FIG. 17.

Then, cleaning liquid is sprayed from the shower unit 84 toward the underside of the wiper blade 81b. This allows new cleaning liquid to adhere to the wiper blade 81b. Next, the wiper blade 81b is rotated in the direction opposite to the direction of arrow A by the wiper drive unit 100, and moves to a vertically upright position. In this state, the wipe movement unit 101 (see FIG. 21) moves the wiping unit 30 forward so that the tip of each wiper blade 81b is positioned at the front end of the corresponding inkjet head 31. The wipe movement unit 101 is composed of a known actuator.

Then, as shown in FIG. 16, the wiping movement unit 101 moves the wiping unit 30 to the wiping position so that the tip of each wiper blade 81b is pressed against the nozzle guard 32 and the ink ejection surface 36a of each inkjet head 31 and is in an elastically deformed state.

Then, with the tip of each wiper blade 81b pressed against each inkjet head, the wiping unit 30 is moved rearward by the wiper movement unit 101 (see FIG. 18), thereby wiping the underside of the nozzle guard 32 and the ink ejection surface 36a of each inkjet head 31.

In this embodiment, the wiping unit 30 is moved in the front-rear direction, but this is not limited thereto, and the head unit 26 may be moved in the front-rear direction. Alternatively, both the wiping unit 30 and the head unit 26 may be moved in opposite directions in the front-rear direction.

After wiping is completed by the tip of each wiper blade 81b moving to the rear end of each inkjet head 31, the head unit 26 is raised a predetermined distance by the head lift motor 25, and the wiping unit 30 is separated a predetermined distance from each inkjet head 31. Note that in this embodiment, the head unit 26 is raised and lowered when wiping, but the wiping unit 30 may be raised and lowered to adjust the distance between the wiper blade 81b and the inkjet head 31.

Then, the wiper blade 81b rotates to the position shown in FIG. 17, and cleaning liquid is sprayed from the shower unit 84 toward the underside of the wiper blade 81b again. This allows the dirt adhering to the underside of the wiper blade 81b to be washed away by the wiping described above.

Next, after the wipe blade 81b is cleaned by the shower unit 84, the wipe blade 81b rotates in the opposite direction and moves again to the position shown in FIG. 13. This completes the wiping operation of the wiping unit 30 in this embodiment.

According to the wiping unit 30 of this embodiment, first, before wiping, cleaning liquid is sprayed from the shower unit 84 onto the wipe blade 81b, so wiping can be performed with the wipe blade 81b that has been cleaned with new, uncontaminated cleaning liquid.

In addition, since cleaning liquid is sprayed from the shower unit 84 onto the wipe blade 81b even after wiping, dirt adhering to the wipe blade 81b due to wiping can be properly removed. This also allows the wipe blade 81b to be immersed in the cleaning tank 83 in a clean state, preventing contamination of the cleaning liquid in the cleaning tank 83.

In other words, the wiping unit 30 of this embodiment can wipe the inkjet head 31 with the wipe blade 81b that is always wet with clean cleaning liquid.

In this embodiment, as described above, the shower unit 84 sprays cleaning liquid before and after wiping the inkjet head 31, but the pressure of the spray before wiping and the pressure of the spray after wiping may be different. For example, it is preferable that the pressure of the spray after wiping is relatively high, since it is necessary to remove dirt that has adhered to the wipe blade 81b by wiping. Furthermore, by making the pressure of the spray before wiping relatively low, it is possible to reduce consumption of cleaning liquid.

The cleaning liquid used is a liquid that dissolves the solidified matter (including ink components, fuzzy surfaces and powder on the surface of the printing medium) attached to the ink ejection surface 36a and the nozzle guard 32. For example, it is preferable to use an aqueous solvent containing water and a surfactant as the cleaning liquid. Examples of the surfactant that can be used include anionic surfactants such as sodium fatty acid, sodium alkylbenzene sulfonate, sodium alkyl sulfonate, sodium α-olefin sulfonate, 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. Polymeric surfactants, silicone surfactants, fluorine surfactants, and acetylene glycol surfactants can also be used. Of 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.

The cleaning solution preferably further contains a thickener. As the thickener, a water-soluble polymer thickener or a clay mineral thickener can be used. As the water-soluble polymer thickener, 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 cleaning liquid stored in the cleaning tank 83 and the cleaning liquid sprayed out from the shower unit 84 do not necessarily have to be the same. For example, it is preferable that the cleaning liquid stored in the cleaning tank 83 is less volatile than the cleaning liquid sprayed out from the shower unit 84. This makes it possible to prevent the cleaning liquid stored in the cleaning tank 83 from volatilizing and decreasing. As such a cleaning liquid, for example, a cleaning liquid containing one or more of an acetylene glycol surfactant, a moisturizer such as glycerin, a water-soluble solvent, and water can be used.

The cleaning liquid sprayed from the shower unit 84 is preferably a cleaning liquid with a higher cleaning ability than the cleaning liquid stored in the cleaning tank 83. Since the wipe blade 81b is immersed in the cleaning tank 83 for a certain period of time, the wipe blade 81b can be sufficiently cleaned even if the cleaning liquid does not have a very high cleaning ability. However, since the cleaning liquid used in the shower unit 84 is sprayed onto the wipe blade 81b, it does not remain on the surface of the wipe blade 81b for a long time. Therefore, by using a cleaning liquid with a high cleaning ability as the cleaning liquid used in the shower unit 84, the wipe blade 81b can be sufficiently cleaned just by spraying it. As such a cleaning liquid, for example, a cleaning liquid containing one or more of an acetylene glycol surfactant, a moisturizer such as glycerin, a water-soluble solvent, and water can be used.

In this embodiment, only one shower unit 84 is provided, but for example, two shower units 84 may be provided facing both sides of the wipe blade 81b, and cleaning liquid may be sprayed onto both sides of the wipe blade 81b.

In addition, in this embodiment, as described above, the shower unit 84 sprays cleaning liquid before and after wiping the inkjet head 31. In this case, however, the time required for the series of wiping operations becomes long, and it takes a long time before the printing operation can start.

Therefore, it is possible to avoid spraying cleaning liquid from the shower unit 84 before wiping the inkjet head 31, and to only spray cleaning liquid from the shower unit 84 after wiping. This can improve productivity.

In addition, in this embodiment, after wiping the inkjet head 31, the shower unit 84 sprays cleaning liquid to remove ink that has flowed down from the inkjet head 31 and adhered to the wipe blade 81b due to wiping. However, there are cases where the ink that has adhered to the wipe blade 81b cannot be removed by just spraying the cleaning liquid.

In addition, when the cleaning liquid is sprayed from the shower unit 84 toward the wipe blade 81b, if the cleaning liquid is sprayed so as to spread, there is a risk that the dirty liquid after cleaning will splash around, so it is preferable to limit the range over which the cleaning liquid spreads. However, if the cleaning liquid is sprayed over such a narrow range, the area over which the cleaning liquid is sprayed on the wipe blade 81b will be narrow, and if ink is attached outside that range, it cannot be removed.

As described above, if the ink adhering to the wipe blade 81b cannot be removed, the wipe blade 81b will be immersed in the cleaning tank 83 in this state, and the cleaning liquid in the cleaning tank 83 will become contaminated with ink. In particular, if ink remains on multiple wipe blades 81b, the different colors of ink will mix together in the cleaning liquid.

If the wipe blade 81b is immersed in the cleaning tank 83 contaminated with ink in this way, the wipe blade 81b with the contaminated cleaning liquid on it will come into contact with the inkjet head 31 during wiping, thereby contaminating the inkjet head 31. This contamination is particularly noticeable when spraying of cleaning liquid by the shower unit 84 before wiping is omitted as described above.

Therefore, in order to more reliably remove the ink adhering to the wiper blade 81b by wiping, the control unit 5 may control the wiper driving unit 100 to rotate the wiper blade 81b in the forward and reverse directions while the cleaning liquid is being sprayed onto the wiper blade 81b after wiping. Note that forward and reverse rotation means rotating (pivoting) in the forward direction and the reverse direction. For example, the direction of arrow A shown in FIG. 13 can be the forward direction. FIG. 18 is a diagram showing how the wiper blade 81b is rotated in the forward and reverse directions as described above. In the example shown in FIG. 18, the wiper blade 81b rotates in the forward and reverse directions within the range of arrow B, with the wiper blade 81b at the position indicated by the solid line as the center. The wiper blade 81b rotates in the forward and reverse directions periodically multiple times within the range of arrow B.

By rotating the wipe blade 81b forward and backward in this way, centrifugal force can be used to remove ink adhering to the wipe blade 81b in a short time. In addition, by rotating the wipe blade 81b forward and backward, the area onto which the cleaning liquid is sprayed by the shower unit 84 can be widened, so the cleaning area on the wipe blade 81b can be widened. In particular, the wipe blade 81b of this embodiment is connected to the blade support member 81a by the blade fixing member 81c, but ink adhering to this blade fixing member 81c may remain. By widening the cleaning area as described above, even ink adhering to the blade fixing member 81c can be removed.

This allows ink adhering to the wipe blade 81b to be removed more reliably, so the cleaning fluid in the cleaning tank 83 can always be kept clean.

When the wiper blade 81b is rotated forward and backward as described above, it is preferable to rotate the wiper blade 81b forward and backward below the horizontal plane including the rotation shaft 82, as shown in FIG. 18. This makes it possible to use the weight of the ink adhering to the wiper blade 81b as well as the centrifugal force, thereby allowing the ink to fall more efficiently.

As for the range in which the wiper blade 81b can rotate forward and backward, it is preferable that the position at which the wiper blade 81b has moved furthest downward (the position indicated by the lower dotted line in FIG. 18) is inclined 15° from the vertically downward direction, and the position at which the wiper blade 81b has moved furthest upward (the position indicated by the upper dotted line in FIG. 18) is inclined 45° from the vertically downward direction. In this case, the range in which the wiper blade 81b can rotate forward and backward, i.e., the range indicated by the arrow B, is 30°.

In addition, when rotating the wipe blade 81b forward and backward as described above, it is preferable to continue rotating it forward and backward even after the shower unit 84 has sprayed the cleaning liquid. This makes it possible to more reliably remove the ink adhering to the wipe blade 81b.

In addition, as described above, when rotating the wiper blade 81b in forward and reverse directions even after the cleaning liquid has been sprayed by the shower unit 84, it is preferable to widen the forward and reverse rotation range after the cleaning liquid has been sprayed compared to the forward and reverse rotation range while the cleaning liquid is being sprayed. This makes it possible to more reliably remove ink remaining on the wiper blade 81b even after the cleaning liquid has been sprayed.

In addition, it is preferable that the rotation speed of the wiper blade 81b when rotating forward and backward is faster than the rotation speed during the series of wiping operations described above. This allows more centrifugal force to be applied to the wiper blade 81b.

In addition, in this embodiment, as described above, the wipe blade 81b is connected to the blade support member 81a using the blade fixing member 81c, but ink or dirty cleaning liquid may get into the gap between the blade fixing member 81c and the wipe blade 81b and may not be removed by simply spraying the cleaning liquid from the shower unit 84. The ink or the like that gets into the gap between the blade fixing member 81c and the wipe blade 81b flows out into the cleaning liquid when immersed in the cleaning tank 83, contaminating the cleaning liquid.

In order to remove the ink and other substances that have entered the gap, a through hole 81e may be formed in the blade fixing member 81c in addition to the screw hole 81d, as shown in FIG. 19. By forming the through hole 81e in the blade fixing member 81c in this way, the cleaning liquid sprayed by the shower unit 84 can flow through the through hole 81e into the gap between the blade fixing member 81c and the wipe blade 81b, and the ink and other substances that have entered the gap can be removed by flowing them onto the wipe blade 81b.

In addition, the configuration for draining ink and the like that has entered the gap between the blade fixing member 81c and the wipe blade 81b onto the wipe blade 81b is not limited to the through hole 81e described above. For example, as shown in FIG. 20, a groove G extending in the length direction of the wipe blade 81b may be formed on the surface of the blade fixing member 81c that contacts the wipe blade 81b. The groove G is formed from the upper end surface to the lower end surface of the blade fixing member 81c. By forming the groove G in this way, the cleaning liquid sprayed by the shower unit 84 can be poured into the groove G, and thus the ink and the like that has entered the gap between the blade fixing member 81c and the wipe blade 81b can be drained onto the wipe blade 81b. Note that a groove may be formed not only on the blade fixing member 81c but also on the wipe blade 81b side at a position opposite the groove G.

Figure 21 is a block diagram showing the control system of the inkjet printing device 1 of this embodiment. The inkjet printing device 1 is equipped with a control unit 5 that controls the entire device. The control unit 5 is equipped with a CPU (Central Processing Unit), a semiconductor memory, a hard disk, etc. The control unit 5 controls each part shown in Figure 21 by executing a program stored in advance in a storage medium such as the semiconductor memory or the hard disk, and by operating an electric circuit.

Next, the printing operation of the inkjet printing device 1 of this embodiment will be described.

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

When a print job is input, the control unit 5 controls the sub-scanning drive motor 12 to move the shuttle unit 4 from the standby position to the print processing start position. The print processing start position of the shuttle unit 4 is the position of the shuttle unit 4 shown by the two-dot chain line in FIG. 1, which is the front end of the stand part 11 of the shuttle base unit 2. Note that prior to input of the print job, the print medium 15 is placed on the medium placement surface 3a of the flatbed unit 3.

The control unit 5 then controls the main scanning drive motor 23 to move the head unit 26 in the main scanning direction, while controlling the inkjet head 31 to eject ink from the ink ejection openings 37 of the nozzles based on the input print job, thereby printing one pass. Next, the control unit 5 controls the sub-scanning drive motor 12 to move the shuttle unit 4 backward to the printing position for the next pass. The control unit 5 alternates between printing one pass and moving the shuttle unit 4, thereby forming an image on the print medium 15.

When printing of one sheet is completed, the control unit 5 controls the sub-scanning drive motor 12 to place the shuttle unit 4 in the standby position. This ends the printing operation.

Next, the cleaning operation of the inkjet printing device 1 of this embodiment will be described with reference to Figures 22 and 23. The cleaning operation of this embodiment is an operation to remove ink that has entered the gap 40 between the nozzle guard 32 and the ink ejection surface 36a, form a meniscus at the ink ejection port 37 of each nozzle, and prevent the water repellency of the nozzle plate 36 from decreasing and the nozzles from drying out.

The cleaning operation is performed when the shuttle unit 4 is placed in the standby position, and at this time, the head unit 26 in the shuttle unit 4 is placed in the standby position shown in Figure 2.

First, as shown in FIG. 22A, with the inkjet head 31 positioned above the capping unit 66, the control unit 5 controls the supply pump 55 to eject ink at a predetermined pressure, thereby performing purging. For example, the purging amount per nozzle is set to about 4.8 mg/s.

During this purging, the opening 46 of the nozzle guard 32 of the inkjet head 31 may be sealed by the cap 71 of the capping unit 66, or may be left open as shown in FIG. 22A. However, it is preferable to seal the opening 46 of the nozzle guard 32 with the cap 71, as sealing in this manner can prevent the intrusion of dust and other debris onto the cap 71 and the area around the cap 71 from being contaminated by ink.

The ink ejected from the inkjet head 31 by the above-mentioned purging is received by the capping unit 66, and is sucked and collected from the capping unit 66 by controlling the suction pump 69 by the control unit 5. This purging causes ink droplets D to adhere to the ink ejection ports 37 of the inkjet head 31, as shown in FIG. 22A.

Next, the control unit 5 waits in the state shown in Fig. 22B until the pressure applied by the supply pump 55 is relaxed and the amount of ink discharged from the nozzles becomes stable. Specifically, when purging is performed for 3 seconds at a pressure at which the amount of ink discharged per nozzle is about 4.8 mg/s, the waiting time is preferably 20 s to 30 s. In this waiting state, the opening 46 of the nozzle guard 32 of the inkjet head 31 may be sealed by the cap 71 of the capping unit 66, or may be open as shown in Fig. 22B. The waiting time may be changed depending on the pressure of the supply pump 55 during purging.

By setting a waiting time in this way, for example, when the head unit 26 is subsequently moved, it is possible to prevent the ink adhering to the ink ejection ports 37 of the inkjet head 31 from falling due to purging, which would cause the inside of the device to become dirty. Also, as described above, by changing the waiting time depending on the pressure of the supply pump 55 during purging, it is possible to reliably wait until the pressure of the supply pump 55 is relieved.

Next, after the above-mentioned waiting time has elapsed, as shown in FIG. 22C, the inkjet head 31 (head unit 26) moves and is positioned above the pressing table 91 of the ink removal section 29. The ink removal section 29 then performs the ink removal operation described above. This ink removal operation makes it possible to remove ink that has entered the gap 40 between the nozzle guard 32 and the ink ejection surface 36a, and to form a meniscus at the ink ejection port 37 of each nozzle. The formation of this meniscus allows for good ink ejection.

After the ink removal operation is completed, the inkjet head 31 (head unit 26) moves and is positioned above the wiping unit 30 as shown in FIG. 23A. The wiping unit 30 then performs the wiping operation described above. This makes it possible to remove dirt adhering to the bottom surface of the nozzle guard 32 of the inkjet head 31 and the ink ejection surface 36a. Furthermore, wiping with the cleaning liquid can also remove components such as resin contained in the ink adhering to the ink ejection surface 36a (components that reduce water repellency), so the water repellency of the ink ejection surface 36a can be restored. Wet wiping with the cleaning liquid can also prevent the nozzles from drying out.

After the wiping operation is completed, the inkjet head 31 (head unit 26) moves and is positioned above the capping unit 66. The capping unit 66 then rises and comes into contact with the inkjet head 31 as shown in FIG. 23B, sealing the opening 46 of the nozzle guard 32 of the inkjet head 31. This concludes the description of the cleaning operation of this embodiment.

When printing is to be performed after the above-mentioned cleaning operation, the capping unit 66 descends, and the head unit 26 is raised by the head lift motor 25 and moved to a predetermined position, after which it moves left and right along the main scanning drive guide 22 to perform the printing process.

After the above-mentioned cleaning operation and before the printing process, the control unit 5 may perform a spitting process in which a small amount of ink is ejected from the inkjet head 31 by controlling the supply pump 55 as necessary. The spitting process is an operation in which the inkjet head 31 ejects a small amount of ink, and may be performed by operating the inkjet head 31 at, for example, 5 kHz to eject ink 1000 times/s. In addition, it is preferable to perform this spitting process with the opening 46 of the nozzle guard 32 of the inkjet head 31 sealed by the capping unit 66, as shown in FIG. 23B.

The cleaning operation may be performed automatically just before the printing process starts, or in response to a user instruction. It may also be performed at preset intervals or after a preset number of prints.

In addition, in the cleaning operation of the above embodiment, the ink removal operation is performed after the purge, but this is not limited to the above, and the periods of the purge and ink removal operations may be overlapped to some extent.

In addition, in the cleaning operation of the above embodiment, the wiping operation is performed by the wiping unit 30 after the ink removal operation is performed by the ink removal unit 29. However, if a print job involves printing a large number of sheets and the cleaning operation is performed during printing, for example, it is also possible to perform only the wiping operation by the wiping unit 30 without performing the ink removal operation.

In addition, in the inkjet printing device 1 of the above embodiment, the wiping unit 30 is equipped with a shower unit 84, but this is not limited to the above, and a configuration that only performs wiping with a wipe blade immersed in a cleaning tank and does not spray cleaning liquid using the shower unit 84 may be used.

The ink removal operation described above is an operation to remove ink that has entered the gap 40 between the nozzle guard 32 and the ink ejection surface 36a, and to form a meniscus at the ink ejection port 37 of each nozzle.

In the ink removal operation, in order to properly remove the ink from the gap 40 as described above and to maintain the meniscus formed in each nozzle, it is desirable to properly set the absorbency and surface roughness of the absorbing member 50, as well as the pressing pressure and pressing time when the absorbing member 50 is pressed against the inkjet head 31 by the pressing table 91.

Specifically, if the absorbency of the absorbing member 50 is low, the ink in the gap 40 of the nozzle guard 32 cannot be properly removed. Also, if the fibers on the surface of the absorbing member 50 are fluffy, the fibers may get into the ink ejection port 37 when pressed against the inkjet head 31, destroying the meniscus.

In addition, the greater the pressing pressure, the more ink inside the gap 40 in the nozzle guard 32 can be pushed out to the outside of the gap 40, making it easier for the absorbing member 50 to absorb it. However, if the pressing pressure is too great, the absorbing member 50 will be pressed too strongly against the ink ejection port 37, destroying the meniscus formed at the ink ejection port 37 and causing ink ejection problems.

In addition, ink that seeps out from the gap 40 of the nozzle guard 32 due to the pressing of the absorbing member 50 may reach the ink ejection port 37 before being absorbed by the absorbing member 50, blocking the ink ejection port 37 and causing ejection failure. Figure 24 shows an example of the state of ink In that seeps out from the gap 40 of the nozzle guard 32 due to the pressing of the absorbing member 50.

In addition, if the pressing time is too short, the ink that seeps out from the gap 40 cannot be sufficiently absorbed, and if the pressing time is too long, the meniscus formed at the ink ejection port 37 may be destroyed.

Considering these factors, it is preferable to use an absorbent member 50 with an absorbency of 10 mm/5 min or more and 80 mm/5 min or less and a surface roughness Rz of 410 μm or less.

It is also preferable to press the absorbing member 50 against the inkjet head 31 with a pressing pressure of 10 kPa or more and 80 kPa or less. It is also preferable that the pressing time be 7 seconds or more and 60 seconds or less.

The basis for the above-mentioned absorbency and surface roughness Rz of the absorbing member 50, as well as the pressing pressure and pressing time of the absorbing member 50, will be shown in the examples described below. By setting the above-mentioned absorbency and surface roughness Rz of the absorbing member 50, as well as the pressing pressure and pressing time of the absorbing member 50, the meniscus can be more appropriately formed, and good ink ejection can be achieved.

As described above, in order to prevent the fibers of the absorbing member 50 from destroying the meniscus formed at the ink ejection port 37, it is preferable that the absorbing member 50 is formed from fibers that are thicker than the diameter of the nozzle. This makes it possible to prevent the fibers of the absorbing member 50 from entering the ink ejection port 37 and destroying the meniscus.

The thickness of the fibers in the absorbent member 50 is measured by observing the top surface of the absorbent member 50 with a Nikon optical microscope "AZ-100M" and measuring the distance between two points with a measuring tool. Specifically, the fibers protruding from the top surface of the absorbent member 50 that has been compressed and flattened are taken as the measurement object, and the two points where the diameter is maximum are specified and the distance between them is measured. The average value of the measurement results for the 10 fibers is then taken as the fiber thickness of the absorbent member 50.

Furthermore, it is preferable that the length of the fibers on the surface of the absorbing member 50 is shorter than the distance from the ink ejection surface 36a of the nozzle to the surface 32a of the nozzle guard (the surface facing the ink ejection surface 36a, see FIG. 4). This makes it possible to prevent the fibers of the absorbing member 50 from entering the ink ejection port 37, and thus makes it possible to prevent the destruction of the meniscus formed at the ink ejection port 37.

The length of the fibers on the surface of the absorbent member 50 is measured by observing the side end surface of the absorbent member 50 with a Nikon optical microscope "AZ-100M" and measuring the distance between two points with a measuring tool. Specifically, the fibers protruding from the top surface of the compressed and flattened absorbent member 50 are the measurement target, and both ends of the protruding part of the fibers are specified and the distance is measured. The average value of the measurement results for 10 fibers is then regarded as the length of the fibers on the surface of the absorbent member 50.

In addition, it is preferable that the spacing between the fibers on the surface of the absorbing member 50 is wider than the nozzle arrangement pitch (the spacing between adjacent nozzles). This makes it possible to prevent the fibers of the absorbing member 50 from entering the ink ejection port 37, and thus to prevent the destruction of the meniscus formed at the ink ejection port 37.

The spacing between the fibers on the surface of the absorbent member 50 is measured by observing the top surface of the absorbent member 50 with a Nikon optical microscope "AZ-100M" and measuring the distance between two points with a measuring tool. Specifically, the fibers protruding from the top surface of the absorbent member 50 that has been compressed and flattened are taken as the measurement object, and two adjacent fibers are specified and the distance between them is measured. The average value of the measurement results for the 10 sets of fibers is then taken as the spacing between the fibers on the surface of the absorbent member 50.

Below, examples and comparative examples will be described with respect to the absorbency and surface roughness Rz of the absorbent member 50, as well as the pressing pressure and pressing time of the absorbent member 50.

First, we will explain how to measure the water absorbency, surface roughness Rz, pressing pressure, and pressing time of the absorbent member 50.

The water absorbency was measured using ink instead of water, in accordance with the water absorbency test based on the Byreck method of JIS L 1907. The test piece was 1 cm wide x 20 cm long, with an initial immersion length of 3 cm and an immersion time of 5 minutes.

Surface roughness Rz is the measured value of maximum height roughness according to ISO 25178 Surface Quality (surface roughness measurement). The measuring device used was a KEYENCE VK-8700 color 3D laser microscope.

The pressing pressure was measured by fixing a push-pull gauge (FGX-50R manufactured by Nidec-Shimpo Corporation) at the same height as the mounting position of the inkjet head, placing an absorbent member on the pressing table, and pressing it against the inkjet head. The pressing time was measured from the time when the pressing pressure reached the value shown in Tables 1 to 4 below to the time when the pressing was released.

Next, we will explain how to evaluate each condition. The evaluation consisted of whether or not the ink in the gap 40 of the nozzle guard 32 was removed (gap ink removal) and whether or not ink was ejected normally from each nozzle (nozzle check).

First, prior to the evaluation, the inkjet printing device was used for a certain period of time, purged, the above-mentioned wiping operation was performed, and a preset nozzle check pattern was printed on the printing medium 15. The printout was then visually inspected to confirm that ink was being ejected normally from all nozzles. For purging, the purge amount per nozzle was set to approximately 4.8 mg/s.

Next, as the evaluation procedure, a roll absorbent member R made of various absorbent members 50 shown in Tables 1 to 4 below was placed as the roll absorbent member R of the ink removal unit 29, and the ink removal unit 29 was controlled with the pressing pressure and pressing time shown in Tables 1 to 4 below to perform the ink removal operation described above.

The gap ink removal was evaluated by pressing the bottom plate 41 (see Figures 3 and 4) of the nozzle guard 32 after the pressing operation with a cotton swab, and visually checking whether ink seeped out from the gap 40. In Tables 1 to 4 below, cases where there was no ink seepage are indicated as "A", cases where there was slight ink seepage are indicated as "B", and cases where there was some ink seepage are indicated as "C". The gap ink removal state is preferably at the level of "A" or "B".

For the nozzle check, a nozzle check pattern was printed after the ink removal operation, and the presence or absence of nozzles that were not ejecting ink normally (missing ejection) was visually confirmed. A nozzle that is not ejecting ink normally is a nozzle where the meniscus has been destroyed, causing ejection defects. The number of nozzles with missing ejection per inkjet head 31 was counted, and in Tables 1 to 4 below, 0 to 3 nozzles are indicated as "A", 4 to 9 nozzles are indicated as "B", and 10 or more nozzles are indicated as "C". Each inkjet head 31 has 508 nozzles. Missing ejection is preferably at the "A" or "B" level.

Next, specific examples will be described. Examples 1 to 11 shown in Table 1 are the results of evaluating gap ink removal and ejection failure when the above pressing operation was performed using various absorbing members 50 with different water absorbencies and surface roughness Rz at the pressing pressures and pressing times shown in Table 1. Here, the pressing pressures were all 30 kPa, and the pressing times were all 10 s.

From the evaluation results shown in Table 1, it was found that the preferable range for the water absorption of the absorbent member 50 is 10 mm/5 min or more and 80 mm/5 min or less. In addition, it was found that the preferable range for the surface roughness Rz of the absorbent member 50 is 410 μm or less.

Next, the absorbent member 50 of Example 3 (printing paper Arabelle (registered trademark)), which has a lower limit of water absorbency, was used and the results of evaluation with varying pressing pressure are shown in Table 2 below. The pressing time was always 10 seconds.

From the evaluation results shown in Table 2, it was found that the pressing pressure is preferably 10 kPa or more and 80 kPa or less. Note that in Example 17, the pressing pressure was too low, which resulted in a grade of "C" for the gap ink removal, and in Example 18, the pressing pressure was too high, which is thought to be why the meniscus was destroyed and the nozzle check was graded "C."

Next, the absorbent member 50 (Acoustic Mute Board (AMB)) of Example 6, which has an upper limit of water absorbency, was used and the results of evaluation with varying pressing time are shown in Table 3 below. The pressing pressure was always 30 kPa.

From the evaluation results shown in Table 3, it was found that the pressing time is preferably 7 seconds or more and 60 seconds or less. In Example 24, the pressing time was too short, so it is believed that the ink that had seeped out from the gap 40 of the nozzle guard 32 reached the ink ejection port 37 of the nozzle before being absorbed by the absorbing member 50, causing an ink ejection failure and resulting in a nozzle check of "C." In Example 25, the pressing time was too long, so it is believed that the meniscus was destroyed and the nozzle check of the nozzle was "C."

Next, based on the evaluation results in Tables 1 to 3, the absorbent member 50 of Example 3 (printing paper Arabelle (registered trademark)), which has a lower limit of water absorbency, was used, and the pressing pressure was set to 10 kPa and 80 kPa, and the pressing time was set to 7 seconds and 60 seconds. The results are shown in Table 4 below (Examples 26 to 29). The absorbent member 50 of Example 6 (AMB), which has an upper limit of water absorbency, was used, and the pressing pressure was set to 10 kPa and 80 kPa, and the pressing time was set to 7 seconds and 60 seconds. The results are shown in Table 4 below (Examples 30 to 33).

From the results in Table 4, it was found that it is preferable to set the water absorbency of the absorbent member 50 to 10 mm/5 min or more and 80 mm/5 min or less, the pressing pressure to 10 kPa or more and 80 kPa or less, and the pressing time to 7 s or more and 60 s or less.

The wiping device of the present invention further includes the following supplementary notes.
(Additional Note)

The wiping device of the present invention can be provided with a control unit that transitions between a state in which the wipe blade is immersed in a cleaning tank, a state in which the tip of the wipe blade is brought into contact with the ink ejection surface to perform wiping, and a state in which cleaning liquid is sprayed onto the wipe blade by the spraying unit.

The wiping device of the present invention can also include a rotation drive unit having a rotation axis provided in the extension direction of the wipe blade and rotating the wipe blade around the rotation axis, and the control unit can control the rotation drive unit to rotate the wipe blade, thereby transitioning the wipe blade between a state in which it is immersed in the cleaning tank, a state in which the tip of the wipe blade is brought into contact with the ink ejection surface to perform wiping, and a state in which cleaning liquid is sprayed onto the wipe blade by the spray unit.

In addition, in the wiping device of the present invention, the spraying section can spray cleaning liquid onto the wipe blade after wiping has been performed.

In addition, in the wiping device of the present invention, the control unit can rotate the wiper blade forward and backward by controlling the rotation drive unit during the operation of spraying cleaning liquid onto the wiper blade after wiping has been performed.

In addition, in the wiping device of the present invention, the control unit can rotate the wipe blade forward and backward by controlling the rotation drive unit after the cleaning liquid is sprayed onto the wipe blade.

In addition, in the wiping device of the present invention, the control unit can rotate the wiper blade forward and backward below a horizontal plane including the rotation axis of the wiper blade.

In addition, in the wiping device of the present invention, the spraying section can spray cleaning liquid onto the wipe blade before wiping is performed.

In addition, in the wiping device of the present invention, the spraying section can have different spray pressures when spraying cleaning liquid before wiping and when spraying cleaning liquid after wiping.

1 Inkjet printing device 2 Shuttle base unit 3 Flatbed unit 3a Medium placement surface 4 Shuttle unit 5 Control unit 11 Frame unit 12 Sub-scanning drive motor 15 Printing medium 21 Housing 22 Main-scanning drive guide 23 Main-scanning drive motor 24 Head lift guide 25 Head lift motor 13A, 13B Sub-scanning drive guide 26 Head unit 28 Suction unit 29 Ink removal unit 29a Winding motor 29b Pressing table lift motor 30 Wiping unit 31 Inkjet head 32 Nozzle guard 36 Nozzle plate 36a Ink ejection surface 37 Ink ejection port 40 Gap 41 Bottom plate 42 Side wall 46 Opening 50 Absorbing member 51 Absorbing member moving unit 53 Ink supply tube 55 Supply pump 66 Capping unit 68 Ink suction tube 69 Suction pump 70 Waste liquid tank 71 Cap 72 Cap base 76 Bottom 77 Peripheral wall 78 Suction hole 80 Housing 80a Hole 81 Wiping section 81a Blade support member 81b Wiper blade 81c Blade fixing member 81d Screw hole 81e Through hole 82 Rotating shaft 83 Cleaning tank 84 Shower section 84a Spray port 85 Inclined surface 86 Cleaning tank pipe 87 Shower section pipe 88 Plate member 90 Cushion section 91 Pressing table 92 Feed roller 93 Winding roller 94 Feed-side transport roller 95 Winding-side transport roller 96 Pressing table lifting mechanism 98 Feed-side transport roller 99 Winding-side transport roller 100 Wiper drive section 101 Wiper moving section G Groove

Claims (6)

a wiper blade for wiping an ink ejection surface of a nozzle array of an inkjet head having a nozzle array in which a plurality of nozzles for ejecting ink are arranged;
a cleaning tank in which a cleaning liquid is stored and in which the wipe blade is immersed;
A spraying unit that sprays a cleaning liquid onto the wipe blade;
a rotation drive unit having a rotation shaft provided in an extension direction of the wiper blade and rotating the wiper blade around the rotation shaft;
The spraying unit sprays a cleaning liquid onto the wipe blade after the wiping is performed,
a control unit that controls the rotation drive unit to rotate the wiper blade in a forward or reverse direction during the operation of spraying cleaning liquid onto the wiper blade after the wiping is performed. The wiping device according to claim 1, wherein the control unit controls the rotation drive unit to transition between a state in which the wipe blade is immersed in the cleaning tank, a state in which the tip of the wipe blade is brought into contact with the ink ejection surface to perform wiping, and a state in which cleaning liquid is sprayed onto the wipe blade by the spray unit. a wiper blade for wiping an ink ejection surface of a nozzle array of an inkjet head having a nozzle array in which a plurality of nozzles for ejecting ink are arranged;
a cleaning tank in which a cleaning liquid is stored and in which the wipe blade is immersed;
A spraying unit that sprays a cleaning liquid onto the wipe blade;
a rotation drive unit having a rotation shaft provided in an extension direction of the wiper blade and rotating the wiper blade around the rotation shaft ;
a control unit for controlling the rotation drive unit to rotate the wiper blade in a forward or reverse direction after the wiper blade has been sprayed with cleaning liquid. The wiping device according to claim 1 or 3, wherein the control unit rotates the wiper blade forward and backward below a horizontal plane including the rotation axis of the wiper blade. The wiping device according to claim 1, wherein the spraying unit sprays cleaning liquid onto the wipe blade before the wiping is performed. a wiper blade for wiping an ink ejection surface of a nozzle array of an inkjet head having a nozzle array in which a plurality of nozzles for ejecting ink are arranged;
a cleaning tank in which a cleaning liquid is stored and in which the wipe blade is immersed;
a spray unit that sprays a cleaning liquid onto the wipe blade,
The spray unit sprays a cleaning liquid onto the wipe blade before and after the wiping is performed,
The wiping device has a different spray pressure when spraying the cleaning liquid before the wiping and a different spray pressure when spraying the cleaning liquid after the wiping.