Inkjet printing device

Abstract

An inkjet printing device capable of reducing ink ejection defects is provided. [Solution] Inkjet heads 31A, 31B each have a nozzle surface 31a with a plurality of nozzles formed therein that eject ink. Shutters 33A, 33B are provided corresponding to inkjet heads 31A, 31B, respectively, and are movable between a position that covers all of the nozzles and a position that is retracted from nozzle surface 31a. A control unit controls, during a printing operation, each of inkjet heads 31A, 31B so that, during a period when at least one of the nozzles has image data to be ejected, the shutters 33A, 33B are positioned so as not to cover the nozzles that have image data to be ejected, and during a period when no image data to be ejected is present for any of the nozzles, the shutters 33A, 33B are positioned so as to cover all of the nozzles.

Description

[Technical Field]

[0001] The present invention relates to inkjet printing devices. [Background technology]

[0002] In an inkjet printing device, ink ejection failure may occur due to drying and thickening of ink inside the nozzles that eject the ink.

[0003] For example, there is a serial inkjet printing device that performs printing while moving an inkjet head, in which a plurality of inkjet heads are arranged at different positions in the direction of movement.

[0004] In such an inkjet printing device, when one pass of printing begins, the inkjet heads begin ejecting ink sequentially, starting with the inkjet heads that are downstream in the direction of inkjet head movement. Therefore, the more upstream the inkjet heads are, the longer the idle running time becomes. The idle running of the inkjet heads is an operation in which the inkjet heads move without ejecting ink, in a state where there is no image data to eject ink onto.

[0005] Furthermore, when one pass of printing is completed, ink ejection is completed in order, starting with the inkjet heads on the downstream side. As a result, the inkjet heads on the downstream side have a longer idle running time.

[0006] When an inkjet head is idle, the ink inside the nozzles dries and thickens, which can lead to poor ink ejection from the nozzles. The longer the idle operation, the more likely such poor ink ejection occurs.

[0007] In particular, inkjet printing devices that have a drying mechanism that heats the print medium onto which ink has been ejected or blows dry air onto the print medium in order to quickly dry the print medium are prone to ink ejection defects due to the dry running operation. Furthermore, the higher the ink drying rate, the more likely it is that ink ejection defects due to the dry running operation will occur.

[0008] As a technique for preventing the ink in the nozzles from drying out and thickening, Patent Document 1 discloses a technique for preventing evaporation of the ink in the nozzles by covering the nozzle rows with shutters when the inkjet recording device is not in operation. [Prior art documents] [Patent documents]

[0009] [Patent Document 1] Japanese Patent Application Laid-Open No. 2007-276394 Summary of the Invention [Problem to be solved by the invention]

[0010] However, the technology of Patent Document 1 cannot deal with the drying and thickening of ink inside the nozzles caused by the idle running of each inkjet head during the printing operation as described above, which can result in ink ejection failure.

[0011] The present invention has been made in view of the above, and has an object to provide an inkjet printing apparatus that can reduce ink ejection defects. [Means for solving the problem]

[0012] In order to achieve the above object, an inkjet printing device of the present invention is characterized by comprising: a plurality of inkjet heads each having a nozzle surface on which a plurality of nozzles for ejecting ink are formed; a plurality of shielding units provided corresponding to each of the plurality of inkjet heads and movable between a position covering all of the nozzles and a position retracted from the nozzle surface; and a control unit that controls, during a printing operation, for each of the plurality of inkjet heads, during a period when image data for ink ejection is present in at least one of the nozzles, to place the shielding unit corresponding to that inkjet head in a position that does not cover the nozzles for which image data for ink ejection is present, and during a period when image data for ink ejection is not present in all of the nozzles, to place the shielding unit corresponding to that inkjet head in a position that covers all of the nozzles. [Effects of the Invention]

[0013] According to the inkjet printing apparatus of the present invention, ink ejection defects can be reduced. [Brief explanation of the drawings]

[0014] [Figure 1] 1 is a perspective view showing a schematic configuration of an inkjet printing apparatus according to a first embodiment. [Figure 2] FIG. 2 is a schematic configuration diagram of a shuttle unit of the inkjet printing apparatus shown in FIG. [Figure 3] 2 is a perspective view showing a schematic configuration of a head unit of the inkjet printing apparatus shown in FIG. 1, in a state where the shutter is placed in an open position. FIG. [Figure 4] 2 is a perspective view showing a schematic configuration of a head unit of the inkjet printing apparatus shown in FIG. 1, in a state where the shutter is placed at a closed position. FIG. [Figure 5] FIG. 2 is a schematic diagram illustrating the configuration of an inkjet head of the inkjet printing apparatus shown in FIG. [Figure 6]2 is a diagram showing the shutter and inkjet head of the inkjet printing apparatus shown in FIG. 1, with the shutter in an open position. FIG. [Figure 7] 2 is a diagram showing the shutter and inkjet head of the inkjet printing device shown in FIG. 1, with the shutter in a closed position. FIG. [Figure 8] FIG. 2 is a control block diagram of the inkjet printing apparatus shown in FIG. [Figure 9] FIG. 10 is a perspective view showing a schematic configuration of a head unit according to a second embodiment, in a state where the shutter is placed in an open position. [Figure 10] FIG. 10 is a perspective view showing a schematic configuration of a head unit according to a second embodiment, in a state where the shutter is placed in a closed position. [Figure 11] FIG. 10 is a schematic diagram of a shutter and a shutter driver according to a second embodiment, showing the shutter in an open position. [Figure 12] FIG. 10 is a schematic diagram of a shutter and a shutter driver according to a second embodiment, showing the shutter in a closed position. DETAILED DESCRIPTION OF THE INVENTION

[0015] Hereinafter, embodiments of the present invention will be described with reference to the drawings. The same or equivalent parts and components are designated by the same or equivalent reference numerals throughout the drawings.

[0016] The following embodiments are examples of devices that embody the technical idea of ​​the present invention, and the technical idea of ​​the present invention does not limit the materials, shapes, structures, arrangements, etc. of each component to those described below. The technical idea of ​​the present invention can be modified in various ways within the scope of the claims.

[0017] [First embodiment] FIG. 1 is a perspective view showing a schematic configuration of an inkjet printing apparatus according to a first embodiment of the present invention. FIG. 2 is a schematic configuration diagram of a shuttle unit of the inkjet printing apparatus shown in FIG. 1. FIGS. 3 and 4 are perspective views showing a schematic configuration of a head unit of the inkjet printing apparatus shown in FIG. 1. FIG. 3 is a diagram showing a state in which the shutter is positioned in an open position, and FIG. 4 is a diagram showing a state in which the shutter is positioned in a closed position. FIG. 5 is a schematic configuration diagram of an inkjet head of the inkjet printing apparatus shown in FIG. 1. FIGS. 6 and 7 are views showing the shutter and inkjet head of the inkjet printing apparatus shown in FIG. 1. FIG. 6 is a diagram showing a state in which the shutter is positioned in an open position, and FIG. 7 is a diagram showing a state in which the shutter is positioned in a closed position. FIG. 8 is a control block diagram of the inkjet printing apparatus shown in FIG. 1. In the following description, the up, down, left, right, front, back, and rear directions indicated by arrows in FIG. 1 are referred to as up, down, left, right, front, and rear directions.

[0018] As shown in FIGS. 1, 2, and 8, the inkjet printing apparatus 1 according to the first embodiment includes a shuttle base unit 2, a flatbed unit 3, a shuttle unit 4, and a control unit 5.

[0019] The shuttle base unit 2 supports the shuttle unit 4 and moves the shuttle unit 4 in the front-rear direction (sub-scanning direction). The shuttle base unit 2 includes a base unit 11 and a sub-scanning drive motor 12.

[0020] The base 11 supports the shuttle unit 4. The base 11 is formed in the shape of a rectangular frame. Sub-scanning drive guides 13 extending in the front-to-rear direction are formed on the left and right frames of the base 11. The sub-scanning drive guides 13 guide the shuttle unit 4 to move in the front-to-rear direction.

[0021] The sub-scanning drive motor 12 moves the shuttle unit 4 in the front-rear direction.

[0022] The flatbed unit 3 holds the print medium 15, which is made of a base material such as a building material or decorative panel. The flatbed unit 3 is disposed inside the mount portion 11 of the shuttle base unit 2. The flatbed unit 3 has a placement surface 3a, which is a horizontal surface on which the print medium 15 is placed. The flatbed unit 3 is designed so that the height of the placement surface 3a can be adjusted by an elevation mechanism such as a hydraulic drive mechanism.

[0023] The shuttle unit 4 prints an image on the print medium 15. The shuttle unit 4 includes a housing 21, a main scanning drive guide 22, a main scanning drive motor 23, a head lift guide 24, a head lift motor 25, a head unit 26, a capping unit 27, and a maintenance unit 28.

[0024] The housing 21 houses each part such as the head unit 26. 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 part 11 of the shuttle base unit 2, and is movable along the sub-scanning drive guide 13.

[0025] 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 in an elongated shape that extends in the left-right direction.

[0026] The main scanning drive motor 23 moves the head unit 26 in the left and right directions.

[0027] The head lift guide 24 guides the head unit 26 to move in the vertical direction. The head lift guide 24 is formed in an elongated shape 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.

[0028] The head lifting motor 25 lifts and lowers the head unit 26 .

[0029] The head unit 26 ejects ink onto the print medium 15 to perform printing while moving left and right along the main scanning drive guide 22. As shown in Figures 3, 4, and 8, the head unit 26 has inkjet heads 31A and 31B, a carriage 32, shutters (corresponding to shielding portions) 33A and 33B, and shutter motors 34A and 34B. Note that the alphabetical suffixes in the reference numerals of the inkjet heads 31A, 31B, etc. may be omitted to refer to them collectively.

[0030] The inkjet head 31 ejects ink onto the print medium 15. As shown in Fig. 5, the inkjet head 31 has four nozzle rows 36 arranged in parallel in the left-right direction.

[0031] Each of the four nozzle rows 36 is formed by a plurality of nozzles 37 arranged in the front-to-rear direction. Each nozzle 37 is formed on a nozzle surface 31a, which is the lower surface of the inkjet head 31. Each nozzle 37 of each nozzle row 36 ejects ink of a different color (for example, cyan, black, magenta, or yellow) for each nozzle row 36.

[0032] 3, the inkjet heads 31A and 31B are arranged in a staggered manner. That is, the inkjet heads 31A and 31B are spaced apart from each other in the left-right direction and are arranged at different positions in the front-rear direction. In this embodiment, the inkjet head 31B is arranged to the right and in front of the inkjet head 31A.

[0033] The carriage 32 holds the inkjet heads 31A and 31B. The carriage 32 is formed in a hollow box shape. The carriage 32 has mounting openings 38A and 38B formed in a bottom plate 32a thereof. The inkjet heads 31A and 31B are mounted in the mounting openings 38A and 38B, respectively, so that the nozzle surfaces 31a are exposed from the carriage 32.

[0034] Shutters 33A and 33B are provided corresponding to inkjet heads 31A and 31B, respectively, and open and close mounting openings 38A and 38B, respectively.

[0035] The shutter 33 is movable back and forth between an open position and a closed position. The open position of the shutter 33 is the position of the shutter 33 in Figures 3 and 6. The open position of the shutter 33 is a position where the entire mounting opening 38 is opened, where the shutter 33 is retracted from the nozzle surface 31a, and where all the nozzles 37 are exposed. Note that Figure 6 shows the inkjet head 31A and the corresponding shutter 33A. The same applies to Figure 7.

[0036] The closed position of the shutter 33 is the position of the shutter 33 in Figures 4 and 7. The closed position of the shutter 33 is a position where the shutter 33 closes the entire attachment opening 38, covers the entire nozzle surface 31a via a space, and covers all of the nozzles 37.

[0037] The shutter 33 may be ink-repellent to prevent staining with ink and to facilitate cleaning. For example, at least one of the front and back surfaces of the shutter 33 may be fluorine-treated or coated with polyimide or the like.

[0038] Shutter motors 34A and 34B move shutters 33A and 33B, respectively.

[0039] The capping unit 27 seals the nozzle surface 31a to prevent the nozzles 37 of the inkjet head 31 from drying out while the inkjet printing apparatus 1 is on standby and not performing a printing operation.

[0040] Furthermore, the capping unit 27 seals the nozzle surface 31a of the inkjet head 31 when purging is performed to discharge ink from the inkjet head 31 during a maintenance operation to clean the inkjet head 31. Furthermore, the capping unit 27 collects the ink discharged from the inkjet head 31 by purging during the maintenance operation as waste liquid.

[0041] The capping unit 27 is disposed inside the right end portion of the housing 21. As shown in FIGS. 2 and 8, the capping unit 27 includes cap portions 41A and 41B, a cap lifting motor 42, suction pipes 43A and 43B, suction pumps 44A and 44B, and a waste liquid tank 45.

[0042] The cap portions 41A and 41B seal the nozzle surfaces 31a of the inkjet heads 31A and 31B, respectively.

[0043] The cap lifting motor 42 lifts and lowers the cap portions 41A and 41B.

[0044] The suction tubes 43A and 43B form ink flow paths from the cap portions 41A and 41B to the waste liquid tank 45, respectively.

[0045] The suction pumps 44A and 44B are used to suck ink from the cap portions 41A and 41B, respectively, and are installed in the suction pipes 43A and 43B, respectively.

[0046] The waste liquid tank 45 stores the ink sent by the suction pumps 44A and 44B as waste liquid.

[0047] The maintenance unit 28 wipes the nozzle surface 31a of the inkjet head 31 during maintenance of the inkjet head 31. The maintenance unit 28 is disposed inside the left end portion of the housing 21. The maintenance unit 28 includes wipers 51A and 51B and a wiper driving unit 52.

[0048] The wipers 51A and 51B are members that wipe the nozzle surfaces 31a of the inkjet heads 31A and 31B, respectively. The wipers 51 wipe the nozzle surfaces 31a while moving in the left-right direction, which is a direction perpendicular to the front-to-back direction, which is the movement direction of the shutter 33. The wiping direction of the wiper 51 may be from left to right or from right to left. The wiper 51 is made of an elastically deformable material such as rubber.

[0049] The wiper driving unit 52 moves the wipers 51A and 51B in the left-right direction and includes a motor and the like (not shown).

[0050] The control unit 5 controls the overall operation of the inkjet printing apparatus 1. The control unit 5 is configured with a CPU, RAM, ROM, a hard disk, and the like.

[0051] Specifically, while moving head unit 26 in the main scanning direction, control unit 5 ejects ink from inkjet head 31 based on image data to be printed, performing one pass of printing, and then moves shuttle unit 4 in the sub-scanning direction. Next, control unit 5 moves head unit 26 in the opposite direction, performing the next pass of printing, and then moves shuttle unit 4 in the sub-scanning direction. Control unit 5 alternately repeats this one-pass printing and the movement of shuttle unit 4, thereby printing an image on print medium 15.

[0052] During this printing operation, the control unit 5 controls the shutters 33A, 33B of each inkjet head 31A, 31B to be in the open position during the non-idle period, and also controls the shutters 33A, 33B of each inkjet head 31A, 31B to be in the closed position during the idle period.

[0053] Here, the idle period of the inkjet head 31 is a period during which the inkjet head 31 performs an idle operation. The idle operation of the inkjet head 31 is an operation in which the inkjet head 31 moves without performing an ink ejection operation in a state in which there is no image data to which ink is to be ejected from any of the nozzles 37 of the inkjet head 31.

[0054] The non-idling period of the inkjet head 31 is a period during which at least one of the nozzles 37 of the inkjet head 31 has image data to be ejected with ink, and at least one of the nozzles 37 is performing the ink ejection operation.

[0055] Next, the printing operation of the inkjet printing apparatus 1 will be described.

[0056] In the inkjet printing device 1, in a standby state before the start of a printing operation, the shuttle unit 4 is placed 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 Figure 1, and is located at the rear end of the stand part 11 of the shuttle base unit 2.

[0057] Furthermore, when the inkjet printing device 1 is in a standby state, the head unit 26 is disposed at the right end of the main scanning drive guide 22, and is disposed in a home position above the capping unit 27. The nozzle surfaces 31a of the inkjet heads 31A and 31B are sealed by the cap portions 41A and 41B, respectively. The shutters 33A and 33B are both disposed in the open position.

[0058] When the nozzle surfaces 31a of the inkjet heads 31A and 31B are sealed by the cap portions 41A and 41B, respectively, spit (blank ejection) may be performed to expel thickened ink or the like from the nozzles 37.

[0059] When a command to start printing is given, 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 Figure 1, which is at the front end of the stand part 11 of the shuttle base unit 2. Note that the print medium 15 is placed on the placement surface 3a of the flatbed unit 3 in advance.

[0060] Next, the control unit 5 controls the cap lifting motor 42 to lower the cap units 41A and 41B, which moves the cap units 41A and 41B away from the nozzle surfaces 31a of the inkjet heads 31A and 31B, thereby releasing the seal on the nozzle surfaces 31a.

[0061] Next, the control unit 5 controls the shutter motors 34A and 34B to move the shutters 33A and 33B to the closed positions.

[0062] Next, the control unit 5 controls the main scanning drive motor 23 to move the head unit 26 to the left, while controlling the inkjet head 31 based on the image data to eject ink from the nozzles 37, thereby printing the first pass.

[0063] In the printing operation of this first pass, the inkjet head 31A on the downstream side in the movement direction of the head unit 26 in this pass reaches the printing medium 15, and then the inkjet head 31B on the upstream side reaches the printing medium 15. The inkjet heads 31A and 31B perform an idle running operation until they each reach the printing medium 15 and start ejecting ink. During the idle running period when this idle running operation is being performed, the shutters 33A and 33B are positioned in the closed position.

[0064] When the idle period before the start of ink ejection operation ends and the non-idle period begins in each of the inkjet heads 31A and 31B, the control unit 5 moves the shutters 33A and 33B from the closed position to the open position. As a result, in the inkjet heads 31A and 31B, all nozzles 37 are exposed during the non-idle period, and ink can be ejected from each nozzle 37 onto the print medium 15.

[0065] At the end of the printing operation of the first pass, the head unit 26 stops at the left end of the main scanning drive guide 22. The inkjet heads 31A and 31B perform idling operation from the end of the ink ejection operation until the head unit 26 stops.

[0066] Therefore, when the ink ejection operation of each of the inkjet heads 31A and 31B ends (when the non-idle running period ends), the control unit 5 moves the shutters 33A and 33B from the open position to the closed position.

[0067] If the inkjet head 31 runs idle with the nozzle surface 31a exposed, the ink inside the nozzles 37 may dry out and become thicker, which may result in poor ink ejection from the nozzles 37.

[0068] Furthermore, if the inkjet printing device 1 is provided with a drying mechanism that heats the printing medium 15 or blows dry air onto the printing medium 15 in order to quickly dry the printing medium 15 onto which ink has been ejected, poor ink ejection is more likely to occur due to the above-mentioned free-running operation.

[0069] Furthermore, when ink with a high solvent evaporation rate or ink with a high drying time due to a high solid content or a high resin content is used, ink ejection failure due to the above-described idle running operation is likely to occur.

[0070] In contrast, in the inkjet printing device 1, the shutter 33 is placed in the closed position to cover the nozzle surface 31a during the idle running period of the inkjet head 31, thereby protecting the nozzles 37 from external wind and heat. This makes it possible to prevent the ink in the nozzles 37 from drying out and becoming thicker due to the idle running operation of the inkjet head 31, thereby reducing ink ejection defects.

[0071] As described above, there is a space between the shutter 33 in the closed position and the nozzle surface 31a. Therefore, even if the inkjet printing device 1 is provided with a drying mechanism as described above, the air layer in the space between the nozzle surface 31a and the shutter 33 prevents heat from being transferred to the nozzles 37, and prevents the ink in the nozzles 37 from drying out and becoming thicker.

[0072] When the printing operation of the first pass is completed, 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.

[0073] Next, the control unit 5 moves the head unit 26 to the right, which is the opposite direction to the printing operation of the first pass, while controlling the inkjet head 31 based on the image data to eject ink from the nozzles 37, thereby printing the second pass.

[0074] During the printing operation of this second pass, as during the printing operation of the first pass described above, the control unit 5 controls the shutters 33A and 33B to be in the closed position during the idle period of each of the inkjet heads 31A and 31B, and to be in the open position during the non-idle period.

[0075] When the printing operation of the second pass is completed, 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.

[0076] Thereafter, the control unit 5 performs printing on the print medium 15 in the same manner by alternately repeating the printing operation for one pass and the movement of the shuttle unit 4.

[0077] During one pass of printing, an idle period may occur during a non-idle period of the inkjet heads 31A and 31B. Even during such an idle period, the control unit 5 places the shutters 33A and 33B in the closed position.

[0078] Furthermore, in a printing operation for one pass, there may be cases where at least one of the inkjet heads 31A and 31B does not have image data onto which ink is to be ejected for the entire period of one pass from all the nozzles 37. For an inkjet head 31 for which there is no image data onto which ink is to be ejected for the entire period of one pass from all the nozzles 37, the entire period of one pass becomes an idle period, and therefore the control unit 5 places the shutter 33 corresponding to that inkjet head 31 in the closed position for the entire period of one pass.

[0079] When printing of one sheet is completed, the control unit 5 controls the main scanning drive motor 23 to place the head unit 26 in the home position. Then, the control unit 5 controls the cap lift motor 42 to raise the cap portions 41A and 41B, sealing the nozzle surfaces 31a of the inkjet heads 31A and 31B with the cap portions 41A and 41B, respectively. The control unit 5 also controls the sub scanning drive motor 12 to place the shuttle unit 4 in the standby position. This completes the printing operation.

[0080] Next, a maintenance operation for the inkjet head 31 in the inkjet printing apparatus 1 will be described.

[0081] First, in a state where the cap portions 41A and 41B seal the nozzle surfaces 31a of the inkjet heads 31A and 31B, respectively, the control portion 5 drives the suction pumps 44A and 44B to suck ink from the nozzles 37 of the inkjet heads 31A and 31B.

[0082] This causes the thickened ink inside the nozzles 37 to be discharged, leaving the ink attached to the nozzle surface 31a. Here, the ink that has been sucked out of the nozzles 37 and dropped into the cap portions 41A and 41B flows into the waste liquid tank 45 via the suction pipes 43A and 43B, respectively.

[0083] Next, the control unit 5 lowers the cap units 41A and 41B to release the sealing of the nozzle surfaces 31a of the inkjet heads 31A and 31B by the cap units 41A and 41B.

[0084] Next, the control unit 5 controls the main scanning drive motor 23 to move the head unit 26 from the home position to above the maintenance unit 28. Thereafter, the control unit 5 controls the head lift motor 25 to lower the head unit 26 to the wiping position. The wiping position of the head unit 26 is a position of the head unit 26 where the wipers 51A and 51B wipe the nozzle surfaces 31a of the inkjet heads 31A and 31B.

[0085] Next, the control unit 5 controls the wiper driving unit 52 to move the wipers 51A and 51B, causing the wipers 51A and 51B to wipe the nozzle surfaces 31a of the inkjet heads 31A and 31B, respectively.

[0086] When wiping of the nozzle surfaces 31a of the inkjet heads 31A and 31B is completed, the control unit 5 controls the head lifting motor 25 to raise the head unit 26 from the wiping position, and then controls the main scanning drive motor 23 to return the head unit 26 to the home position.

[0087] Next, the control unit 5 controls the cap lift motor 42 to lift the cap units 41A and 41B, and seals the nozzle surfaces 31a of the inkjet heads 31A and 31B with the cap units 41A and 41B, respectively. This completes the maintenance operation for the inkjet head 31.

[0088] As described above, in the inkjet printing device 1, the control unit 5 controls the shutters 33A, 33B of each inkjet head 31A, 31B to be placed in the closed position during the idle running period during printing operation. This makes it possible to suppress drying and thickening of the ink inside the nozzles 37 due to the idle running operation of each inkjet head 31A, 31B during printing operation, thereby reducing ink ejection defects.

[0089] Furthermore, in the inkjet printing device 1, the movement direction of the wiper 51 is perpendicular to the front-to-rear direction, which is the movement direction of the shutter 33. This reduces the possibility that ink collected by the wiper 51 wiping the nozzle surface 31a will solidify within the range of movement of the shutter 33 and interfere with the operation of the shutter 33.

[0090] [Second embodiment] Next, a second embodiment in which the head unit of the first embodiment described above is modified will be described.

[0091] Figures 9 and 10 are perspective views showing the schematic configuration of a head unit according to the second embodiment. Figure 9 is a view showing the state in which the shutter is disposed in the open position, and Figure 10 is a view showing the state in which the shutter is disposed in the closed position. Figures 11 and 12 are schematic configuration diagrams of the shutter and shutter drive unit according to the second embodiment. Figure 11 is a view showing the state in which the shutter is disposed in the open position, and Figure 12 is a view showing the state in which the shutter is disposed in the closed position.

[0092] As shown in Figures 9 to 12, head unit 26A of the second embodiment has a configuration in which shutters 33A, 33B and shutter motors 34A, 34B of head unit 26 of the first embodiment described above are replaced with shutters 61A, 61B and shutter drive units 62A, 62B.

[0093] The shutter 61 is formed by a plurality of plate members 66 arranged in the front-rear direction when the shutter 61 is placed in the closed position.

[0094] The plate member 66 is formed in a rectangular shape that is elongated in the left-right direction. The plate member 66 has connection portions 66a formed on the left and right ends thereof, and is connected to wires 71, which will be described later, at the connection portions 66a. The plate member 66 may be ink-repellent, similar to the shutter 33 of the first embodiment.

[0095] 11 and 12, shutter driving unit 62A includes two wires 71 (only one wire is shown in FIGS. 11 and 12), winding rollers 72 and 73, and a guide roller 74.

[0096] The plate member 66 of the shutter 61A is attached to the wire 71. One end of the wire 71 is wound around the winding roller 72, and the other end is wound around the winding roller 73. One of the two wires 71 is wound around the left end of the winding rollers 72 and 73. The other wire 71 is wound around the right end of the winding rollers 72 and 73.

[0097] One wire 71 is connected to the connection portion 66a at the left end of each plate member 66 of the shutter 61A, and the other wire 71 is connected to the connection portion 66a at the right end of each plate member 66.

[0098] The winding rollers 72, 73 rotate to wind and unwind the wire 71, thereby moving the shutter 61A between the open position and the closed position. The winding rollers 72, 73 are formed in a cylindrical shape extending in the left-right direction. The winding roller 72 is disposed above and behind the winding roller 72. The winding rollers 72, 73 are each rotated by a motor (not shown).

[0099] The guide roller 74 guides the wire 71 between the winding rollers 72, 73. The guide roller 74 is formed in a cylindrical shape extending in the left-right direction. The guide roller 74 is located at the same height as the winding roller 72 in the up-down direction and at the same position as the winding roller 73 in the front-to-rear direction. As a result, the wire 71 extends in the front-to-rear direction between the winding roller 72 and the guide roller 74, and extends in the up-to-down direction between the guide roller 74 and the winding roller 73.

[0100] As shown in FIG. 12, the shutter 61 is in the closed position between the winding roller 72 and the guide roller 74.

[0101] The open position of the shutter 61 is a position retracted upward from the closed position, as shown in Figure 11. When in the open position, the shutter 61, excluding some of the plate members 66, is located between the guide roller 74 and the winding roller 73.

[0102] The shutter driver 62B has a configuration in which the shutter driver 62A is reversed front to back.

[0103] As described above, in the second embodiment, the open position of the shutter 61 is set to a position retracted upward from the closed position, thereby making it possible to reduce the size of the shutter drivers 62A and 62B in the front-rear direction.

[0104] [Other embodiments] As described above, the present invention has been described by the first and second embodiments, but the descriptions and drawings that form part of this disclosure should not be understood to limit the present invention. Various alternative embodiments, examples, and operating techniques will become apparent to those skilled in the art from this disclosure.

[0105] In the first and second embodiments described above, during the non-idle running period, the shutters 33, 61 are placed in the open position where they are retracted from the nozzle surface 31a.

[0106] However, the shutters 33, 61 may be positioned to cover only the nozzles 37 that do not have image data for ink ejection during the non-idle running period. It is sufficient that the shutters 33, 61 are positioned so as not to cover the nozzles 37 that have image data for ink ejection.

[0107] As described above, by positioning the shutters 33, 61 in a position that covers only the nozzles 37 that do not have image data for ink ejection during the non-idle running period, it is possible to suppress the drying and thickening of ink inside the nozzles 37 due to the idle running operation on a nozzle 37 basis, thereby further reducing poor ink ejection.

[0108] Here, if the range in which only nozzles 37 that do not have image data to eject ink exist fluctuates during the non-idle period, the positions of the shutters 33, 61 can be adjusted in accordance with the fluctuation. For example, in the first embodiment, if ejection operations are performed sequentially from the front nozzles 37 in all nozzle rows 36 of the inkjet head 31A, the shutter 33A can be gradually moved rearward as the front end of the range in which only nozzles 37 that are not ejecting exist gradually moves rearward.

[0109] In the first and second embodiments described above, the wiper 51 moves to wipe the nozzle surface 31a of the inkjet head 31, but a fixed wiper may also be used to wipe the nozzle surface of the moving inkjet head. The wiper may be any type that moves relative to the inkjet head to wipe the nozzle surface.

[0110] In the first and second embodiments described above, the movement direction of the wiper 51 is perpendicular to the movement direction of the shutters 33 and 61. However, this is not limiting, and the relative movement direction of the wiper with respect to the inkjet head may be any direction that intersects with (is non-parallel to) the movement direction of the shutter.

[0111] In the first and second embodiments described above, the inkjet printing device 1 is a serial type in which two inkjet heads 31A, 31B are arranged in a staggered manner. However, the number and arrangement of the inkjet heads are not limited to this, and the present invention is not limited to a serial type. The present invention is applicable to inkjet printing devices equipped with multiple inkjet heads.

[0112] As such, the present invention naturally includes various embodiments not described herein. Therefore, the technical scope of the present invention is defined only by the invention-specifying matters according to the scope of the claims that are appropriate from the above description.

[0113] [Note] The present application discloses the following inventions.

[0114] (Appendix 1) a plurality of inkjet heads each having a nozzle surface on which a plurality of nozzles for ejecting ink are formed; a plurality of shielding units provided corresponding to the plurality of inkjet heads, the shielding units being movable between a position covering all of the nozzles and a position retracted from the nozzle surface; a control unit that controls, for each of the plurality of inkjet heads during a printing operation, to place the shielding unit corresponding to the inkjet head at a position that does not cover the nozzles that have image data for ink ejection targets in at least one of the nozzles, and to place the shielding unit corresponding to the inkjet head at a position that covers all of the nozzles in a period when no image data for ink ejection targets is present in any of the nozzles; An inkjet printing apparatus comprising:

[0115] (Appendix 2) The inkjet printing device described in Appendix 1 is characterized in that during printing operation, for each of the multiple inkjet heads, during a period when image data for ink ejection is present in at least one of the nozzles, the control unit controls the shielding unit corresponding to that inkjet head to be positioned to cover only the nozzles that do not have image data for ink ejection.

[0116] (Appendix 3) a wiper that wipes the nozzle surface while moving relatively to the inkjet head; 3. The inkjet printing device according to claim 1, wherein the direction of relative movement of the wiper with respect to the inkjet head is a direction intersecting the direction of movement of the shielding portion. [Explanation of symbols]

[0117] 1. Inkjet printing device 2 Shuttle Base Unit 3 Flatbed Unit 4 Shuttle Unit 5. Control section 11 Mounting section 12 Sub-scanning drive motor 13 Sub-scanning drive guide 15 Print media 21. Cabinet 22 Main scanning drive guide 23 Main scanning drive motor 24 Head lift guide 25 Head lift motor 26 Head Unit 27 Capping unit 28 Maintenance Unit 31, 31A, 31B Inkjet head 31a Nozzle surface 32 Carriage 33, 33A, 33B shutter 34, 34A, 34B Shutter motor 36 nozzle rows 37 nozzle 38, 38A, 38B Mounting opening 41A, 41B Cap part 42 Cap lifting motor 43A,43B Suction tube 44A, 44B suction pump 45 Waste tank 51, 51A, 51B wipers 52 Wiper drive unit 61, 61A, 61B shutter 62A, 62B Shutter drive unit 66 Plate members 66a Connection 71 Wire 72,73 Winding roller 74 Guide roller

Claims

1. a plurality of inkjet heads each having a nozzle surface on which a plurality of nozzles for ejecting ink are formed; a plurality of shielding units provided corresponding to the plurality of inkjet heads, the shielding units being movable between a position covering all of the nozzles and a position retracted from the nozzle surface; a control unit that controls, for each of the plurality of inkjet heads during a printing operation, to place the shielding unit corresponding to the inkjet head at a position that does not cover the nozzles that have image data for ink ejection targets in at least one of the nozzles, and to place the shielding unit corresponding to the inkjet head at a position that covers all of the nozzles in a period when no image data for ink ejection targets is present in any of the nozzles; An inkjet printing apparatus comprising:

2. 2. The inkjet printing device according to claim 1, wherein the control unit controls, for each of the plurality of inkjet heads during a printing operation, the shielding unit corresponding to that inkjet head to be positioned to cover only the nozzles that do not have image data for ink ejection during a period when image data for ink ejection is present in at least one of the nozzles.

3. a wiper that wipes the nozzle surface while moving relatively to the inkjet head; 3. The inkjet printing apparatus according to claim 1, wherein the direction of relative movement of the wiper with respect to the inkjet head is a direction intersecting the direction of movement of the shielding portion.

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