Inkjet printing device

Abstract

To prevent a discharge failure after rotation of an ink jet head for discharging ink in a horizontal direction in an ink jet printer.SOLUTION: An ink jet printer 1 includes: an ink jet head 10 which discharges ink IK in a horizontal direction D2 crossing a vertical direction; a rotating mechanism 20 which rotates the ink jet head 10 at a lateral printing angle during printing and at a stand-by angle during non-printing; an ink flow passage which is connected to the ink jet head 10 so as to make the ink IK flow; each of a pressure tank 31 and a negative pressure tank 34 which is connected to the ink flow passage and is one example of a tank for storing the ink IK; atmosphere open valves 35a, 36a which open gas of the pressure tank 31 and the negative pressure tank 34 to the atmosphere; and a control section 71 which closes the atmosphere open valves 35a, 36a (step S1) during rotation of the ink jet head 10 (step S2 to S5).SELECTED DRAWING: Figure 8

Description

[Technical Field]

[0001] The present invention relates to an inkjet printing device that prints laterally on a substrate. [Background technology]

[0002] A horizontal printing method is known in the past, in which inkjet printing is performed horizontally on the side of cardboard, paper, etc. In this horizontal printing method, the inkjet head faces horizontally during printing, and during maintenance, the inkjet head is rotated 90 degrees downward in an open-to-air state (see, for example, Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2014-136396 Summary of the Invention [Problem to be solved by the invention]

[0004] As described above, when an inkjet head that ejects ink horizontally is rotated downward during maintenance or rotated horizontally after maintenance, the vibrations caused by the rotation can destroy the ink meniscus in the nozzles of the inkjet head. This meniscus is the shape of the tip of the ink ejection direction. If the meniscus is destroyed, the inkjet head will no longer be able to eject ink properly during printing.

[0005] SUMMARY OF THE INVENTION An object of the present invention is to provide an inkjet printing apparatus that can prevent ejection defects after rotation of an inkjet head that ejects ink in a lateral direction. [Means for solving the problem]

[0006] In one embodiment, an inkjet printing device includes an inkjet head that ejects ink in a horizontal direction that intersects with the vertical direction, a rotation mechanism that rotates the inkjet head to a horizontal printing angle when printing and to a standby angle when not printing, an ink flow path that is connected to the inkjet head and through which ink flows, a tank that is connected to the ink flow path and stores ink, an air release valve that releases gas in the tank to the atmosphere, and a control unit that closes the air release valve when the inkjet head is rotating. [Effects of the Invention]

[0007] According to this aspect, it is possible to prevent ejection defects after rotation of an inkjet head that ejects ink in the lateral direction. [Brief explanation of the drawings]

[0008] [Figure 1] FIG. 2 is a plan view illustrating horizontal printing by an inkjet head according to an embodiment. [Figure 2] FIG. 2 is a front view illustrating horizontal printing by an inkjet head according to an embodiment. [Figure 3] FIG. 2 is a diagram illustrating a configuration of an ink circulation unit according to an embodiment. [Figure 4] FIG. 2 is a left side view showing the inkjet head and the rotation mechanism according to the embodiment. [Figure 5] FIG. 2 is a diagram illustrating a control configuration of an inkjet printing apparatus according to an embodiment. [Figure 6] FIG. 2 is a left side view showing the inkjet head in a maintenance state (standby angle) according to the embodiment. [Figure 7] FIG. 10 is a left side view showing the inkjet head in the middle of rotation from the standby angle to the printing angle in one embodiment. [Figure 8] 10 is a flowchart illustrating a process from the end of maintenance to the start of printing according to an embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0009] An inkjet printing apparatus according to an embodiment of the present invention will now be described with reference to the drawings.

[0010] 1 and 2 are a plan view and a front view for explaining lateral printing by an inkjet head 10 according to an embodiment.

[0011] Note that the front-to-back, left-to-right, and up-to-down directions in Figures 1 and 2 and Figures 4, 6, and 7 described below are examples for the convenience of explanation when the conveying direction D1 of the conveyor 100 is set to the right, and the front-to-back and left-to-right directions are horizontal directions, and the up-to-down direction is vertical.

[0012] As shown in FIG. 1, the inkjet head 10 is disposed at the front side of the conveyor 100. The inkjet head 10 ejects ink in a lateral direction D2 onto a printing substrate M being conveyed on the conveyor 100 in a conveyance direction D1, thereby performing printing. This lateral direction D2 is a direction (rearward in FIG. 1) that intersects with the vertical direction (up and down direction in FIG. 1) and the conveyance direction D1 of the printing substrate M (rightward in FIG. 1), and is, for example, a horizontal direction. However, the lateral direction D2 is not limited to a horizontal direction, and may be a direction inclined up or down relative to the horizontal direction. The printing substrate M is, for example, a box such as cardboard, but may also be paper or the like, and is not particularly limited.

[0013] Here, the inkjet printing apparatus 1 equipped with the inkjet head 10 further includes a rotation mechanism 20 shown in FIG. 4, an ink circulation unit 30 and an ink supply unit 50 shown in FIG. 3, a purge tray 60 shown in FIG. 6, and a control unit 71, a memory unit 72, and an interface unit 73 shown in FIG. 5. A system equipped with the inkjet printing apparatus 1 and the conveyor 100 shown in FIGS. 1 and 2 can be called a printing system. As an example, the conveyor 100 is a belt conveyor arranged as part of a box-making machine. Note that the conveyor 100 may be a conveyor other than a belt conveyor, such as a roller conveyor.

[0014] As shown in Fig. 2, the inkjet head 10 has a plurality of head modules 11 (which are shown by hidden dashed lines because they are located at the rear side of the inkjet head 10, not visible in Fig. 2). For example, the inkjet head 10 has six head modules 11 for each of the colors black, cyan, magenta, and yellow. The six head modules 11 for each color are arranged in a staggered pattern in the height direction, with their positions in the left-right direction (transport direction D1) varying.

[0015] The inkjet head 10 prints text such as "XX apple" and "Harvest date *month*day" (variable printing for *) in four colors (full color), for example, black, cyan, magenta, and yellow, or prints a pattern of two apples on the side (front) of the printing substrate M.

[0016] Although not shown in Figures 1 and 2, the printing material M being transported on the conveyor 100 may be guided by a transport guide located on the rear side of the conveyor 100, and the inkjet head 10 may print on the printing material M guided in this manner.

[0017] FIG. 3 is a diagram showing the configuration of the ink circulation unit 30. As shown in FIG.

[0018] The inkjet head 10 shown in Fig. 3 has an ink chamber (not shown) that stores ink IK and a plurality of nozzles (not shown) that eject the ink IK. A piezoelectric element (not shown) is disposed within the ink chamber. Driving the piezoelectric element ejects the ink IK from the nozzle.

[0019] The ink circulation unit 30 includes a pressurized tank 31, a distributor 32, a collector 33, a negative pressure tank 34, an ink pump P1, a pressurized common air chamber 35, a negative pressure common air chamber 36, an air pump P2, a temperature adjustment unit 37, ink circulation pipes 38a, 38b, 38c, a supply tube 39a, and a discharge tube 39b. Note that, except for the pressurized common air chamber 35, the negative pressure common air chamber 36, and the air pump P2, the ink circulation unit 30 is provided for each color of ink IK ejected by the head module 11 of the inkjet head 10.

[0020] The pressurized tank 31, the ink circulation pipe 38a, the distributor 32, the supply tube 39a, the discharge tube 39b, the collector 33, the ink circulation pipe 38b, the negative pressure tank 34, and the ink circulation pipe 38c are examples of an ink flow path that is connected to the inkjet head 10 and through which the ink IK flows, and constitute a circulation flow path that circulates the ink IK while supplying the ink IK to the inkjet head 10.

[0021] The pressurized tank 31 stores the ink IK to be supplied to the inkjet head 10. The ink IK in the pressurized tank 31 is supplied to the inkjet head 10 via the ink circulation pipe 38a, the distributor 32, and the supply tube 39a. An air layer is formed above the liquid surface of the ink IK inside the pressurized tank 31. The pressurized tank 31 is located at a lower position than the inkjet head 10. The pressurized tank 31 is connected to the ink flow path (ink circulation pipes 38a, 38c) and is an example of a tank that stores the ink IK.

[0022] The distributor 32 distributes the ink IK supplied from the pressure tank 31 via the ink circulation pipe 38 a to each head module 11 of the inkjet head 10 .

[0023] The collector 33 collects the ink IK that has not been consumed by the inkjet head 10 from each head module 11 via a discharge tube 39b. The ink IK collected by the collector 33 flows to the negative pressure tank 34 via an ink circulation pipe 38b.

[0024] The negative pressure tank 34 receives and stores the ink IK that has not been consumed by the inkjet head 10 from the collector 33. The negative pressure tank 34 also stores the ink IK supplied from the ink cartridges 51 of the ink supply unit 50, which will be described later. An air layer is formed above the liquid surface of the ink IK inside the negative pressure tank 34. The negative pressure tank 34 is disposed at the same height as the pressurized tank 31. Like the pressurized tank 31 described above, the negative pressure tank 34 is connected to the ink flow path (ink circulation pipes 38b, 38c) and is an example of a tank that stores the ink IK.

[0025] The negative pressure tank 34 is provided with a liquid level detection sensor (not shown) that detects whether the liquid level of the ink IK in the negative pressure tank 34 has reached a reference level.

[0026] The ink pump P1 supplies the ink IK from the negative pressure tank 34 to the pressure tank 31. The ink pump P1 is provided midway along the ink circulation pipe 38c.

[0027] The pressurized common air chamber 35 is an air chamber for equalizing the pressures of the multiple pressurized tanks 31 corresponding to each color of ink IK. The pressurized common air chamber 35 has an atmosphere release valve 35a and a pressure sensor 35b. The atmosphere release valve 35a switches the pressurized common air chamber 35 between a sealed state (a state cut off from the atmosphere) and an atmosphere open state (a state connected to the atmosphere). The pressure sensor 35b detects the pressure inside the pressurized common air chamber 35.

[0028] The negative pressure common air chamber 36 is an air chamber for equalizing the pressures of the multiple negative pressure tanks 34 corresponding to each color of ink IK. The negative pressure common air chamber 36 has an atmosphere release valve 36a and a pressure sensor 36b. The atmosphere release valve 36a switches the negative pressure common air chamber 36 between a sealed state (a state cut off from the atmosphere) and an atmosphere open state (a state connected to the atmosphere). The pressure sensor 36b detects the pressure inside the negative pressure common air chamber 36.

[0029] The air pump P2 sends air from the negative pressure common air chamber 36 to the pressurized common air chamber 35. When the air pump P2 is operating, the atmosphere release valve 35a of the pressurized common air chamber 35 is closed to seal the pressurized common air chamber 35, thereby generating pressure (positive pressure) in the pressurized common air chamber 35. When the air pump P2 is operating, the atmosphere release valve 36a of the negative pressure common air chamber 36 is closed to seal the negative pressure common air chamber 36, thereby generating pressure (negative pressure) in the negative pressure common air chamber 36. Since the pressurized tank 31 and the pressurized common air chamber 35 are in communication and the negative pressure tank 34 and the negative pressure common air chamber 36 are in communication, the air pump P2 functions as an example of a pressure adjustment unit that adjusts the pressure of the gas in the tanks (the pressurized tank 31 and the negative pressure tank 34). The control unit 71, which will be described later, can adjust the gas pressure in the pressurized common air chamber 35 and the negative pressure common air chamber 36, and therefore the gas pressure in the pressurized tank 31 and the negative pressure tank 34, by controlling the air pump P2 based on the detection results of the pressure sensors 35b and 36b.

[0030] The temperature adjustment unit 37 is provided midway along the ink circulation pipe 38a. The temperature adjustment unit 37 has, for example, a heat sink, a cooling fan, a heater, etc., and adjusts the temperature of the ink IK flowing through the ink circulation pipe 38a.

[0031] The ink circulation pipe 38a connects the pressurized tank 31 and the distributor 32. Ink IK flows through the ink circulation pipe 38a from the pressurized tank 31 toward the distributor 32. The ink circulation pipe 38b connects the collector 33 and the negative pressure tank 34. Ink IK flows through the ink circulation pipe 38b from the collector 33 toward the negative pressure tank 34. The ink circulation pipe 38c connects the negative pressure tank 34 and the pressurized tank 31. Ink IK flows through the ink circulation pipe 38c from the negative pressure tank 34 toward the pressurized tank 31.

[0032] The supply tube 39a is made of an elastic material, for example, with an outer layer made of polyurethane resin and an inner layer made of fluororesin, and supplies the ink IK from the distributor 32 to the head module 11. The number of supply tubes 39a provided is the same as the number of head modules 11. The supply tube 39a is an example of a supply flow path that flows the ink IK supplied to the inkjet head 10. The ink circulation pipe 38a and the like can also be called a supply flow path.

[0033] The discharge tube 39b is made of an elastic material, for example, with an outer layer made of polyurethane resin and an inner layer made of fluororesin, and discharges the ink IK from the head module 11 to the collector 33. The number of discharge tubes 39b provided is the same as the number of head modules 11. The discharge tube 39b is an example of a discharge flow path that flows the ink IK discharged from the inkjet head 10. The ink circulation pipe 38b and the like can also be called a discharge flow path.

[0034] During purging, which is performed with the inkjet head 10 facing downward, which is the standby angle for non-printing, as described below, the air release valves 35a, 36a of the pressurized common air chamber 35 and the negative pressure common air chamber 36 are closed and the air pump P2 is driven to generate a set purge pressure in the pressurized tank 31 and the negative pressure tank 34, respectively. Purging is a process in which ink IK is supplied from the pressurized tank 31 to the inkjet head 10, thereby forcibly discharging the ink IK from the nozzles of each head module 11. After purging is completed, the air release valves 35a, 36a of the pressurized common air chamber 35 and the negative pressure common air chamber 36 are switched to an open state.

[0035] The ink supply unit 50 supplies (supplies) the ink IK to the negative pressure tank 34 of the ink circulation unit 30. The ink supply unit 50 includes an ink cartridge 51, an ink supply valve 52, and an ink supply pipe 53.

[0036] The ink cartridge 51 contains the ink IK used for printing by the inkjet head 10. The ink IK in the ink cartridge 51 is supplied to the negative pressure tank 34 of the ink circulation unit 30 via an ink supply pipe 53.

[0037] The ink supply valve 52 is an electromagnetic valve that opens and closes the flow path of the ink IK in the ink supply pipe 53. When the ink IK is to be supplied to the negative pressure tank 34, the ink supply valve 52 is opened under the control of the control unit 71, which will be described later.

[0038] The ink supply pipe 53 connects the ink cartridge 51 and the negative pressure tank 34. Ink IK flows through the ink supply pipe 53 from the ink cartridge 51 toward the negative pressure tank 34.

[0039] FIG. 4 is a left side view showing the inkjet head 10 and the rotation mechanism 20. As shown in FIG.

[0040] The rotation mechanism 20 shown in FIG. 4 includes a rotation drive unit 21, a rotating member 22, and a rotation position detection sensor 23. The rotation mechanism 20 rotates the inkjet head 10 to a horizontal printing angle (horizontal orientation shown in FIG. 4) when printing, and to a standby angle (downward orientation shown in FIG. 6, described later) when not printing. Note that this standby angle is not limited to a vertically downward angle, but may be an angle different from the horizontal orientation printing angle. The angle of the standby angle relative to the horizontal may also be the same as the printing angle. In this case, the inkjet head 10 rotates between the printing angle and the standby angle around a rotation central axis extending vertically.

[0041] The rotation drive unit 21 is, for example, an actuator such as a motor, a solenoid, etc. Note that Fig. 4 shows the output shaft (gear of the output shaft) of the rotation drive unit 21.

[0042] The rotating member 22 is, for example, a gear that rotates around a rotation central axis (not shown) that extends in the left-right direction, and the inkjet head 10 is fixed to the left side surface of the rotating member 22. The rotating member 22 meshes with the rotation drive unit 21 and is rotated by the drive of the rotation drive unit 21. Accordingly, the inkjet head 10 fixed to the rotating member 22 also rotates.

[0043] Notches 22a and 22b are provided around the periphery of the rotating member 22, spaced apart by a rotation angle of 90 degrees of the rotating member 22. Notch 22a is detected by the rotational position detection sensor 23 when the inkjet head 10 is at a printing angle (landscape as shown in FIG. 4) when printing. Notch 22b is detected by the rotational position detection sensor 23 when the inkjet head 10 is at a standby angle (downward as shown in FIG. 6) when not printing.

[0044] As described above, rotational position detection sensor 23 can detect the rotational angle of rotating member 22 depending on whether or not it detects notches 22a, 22b of rotating member 22. The rotational angle of rotating member 22 (inkjet head 10) detected by rotational position detection sensor 23 is acquired by control unit 71, which will be described later. Note that control unit 71 may acquire the rotational angle of rotating member 22 (inkjet head 10) based on the number of pulses when rotation drive unit 21 is a stepping motor, or the detection result of a rotational position detection sensor such as an encoder provided in rotation drive unit 21.

[0045] FIG. 5 is a diagram showing the control configuration of the inkjet printing apparatus 1.

[0046] 5 has a processor (e.g., CPU: Central Processing Unit) that functions as an arithmetic processing device that controls the overall operation of the inkjet printing apparatus 1. The control unit 71 controls each part of the inkjet printing apparatus 1, such as the inkjet head 10, the rotation mechanism 20, the ink circulation unit 30, and the ink supply valve 52. As will be described later, the control unit 71 closes the atmosphere release valves 35a and 36a of the pressurized common air chamber 35 and the negative pressure common air chamber 36 when the inkjet head 10 is rotating.

[0047] The storage unit 72 has, for example, memory such as a ROM (Read Only Memory), which is a read-only semiconductor memory in which predetermined control programs are pre-recorded, and a RAM (Random Access Memory), which is a semiconductor memory that can be written to and read at any time and is used as a working memory area as needed when the processor executes various control programs.

[0048] The interface unit 73 exchanges various information with external devices such as a print control device, a user terminal, etc. For example, the interface unit 73 receives a print job including image data to be printed.

[0049] Next, the operation of the inkjet head 10 and the rotation mechanism 20 will be described with reference to FIGS.

[0050] FIG. 6 is a left side view showing the inkjet head 10 in a maintenance state (standby angle).

[0051] FIG. 7 is a left side view showing the inkjet head 10 in the middle of rotation from the standby angle to the printing angle in one embodiment.

[0052] FIG. 8 is a flowchart for explaining the process from the end of maintenance to the start of printing.

[0053] First, as shown in FIG. 4, the inkjet head 10 ejects ink IK in the lateral direction D2 during printing.

[0054] Thereafter, when maintenance such as the above-mentioned purging is performed, when the power is turned off, when there is a long period of time in which printing is not performed, or when a standby operation is performed by the user on an operation panel (not shown) of the inkjet printing device 1, the inkjet head 10 rotates 90 degrees to face downward, which is the standby angle for when not printing, as shown in Fig. 6. When purging is performed, a purge tray 60 is moved below the inkjet head 10 either manually by a maintenance technician or a general user, or automatically. This purge tray 60 stores the ink IK purged from the inkjet head 10.

[0055] The processing of the flowchart in Fig. 8 is started by the control unit 71 when the inkjet head 10 is rotated to a horizontal printing angle after purging (maintenance) has finished, the inkjet head 10 is at a standby angle facing downward, and the atmosphere release valves 35a, 36a of the pressurized common air chamber 35 and the negative pressure common air chamber 36 are in an open state. Note that, with regard to the explanation of the flowchart in Fig. 8, explanations of matters that overlap with the explanation above will be omitted.

[0056] First, the control unit 71 closes the air release valves 35a, 36a of the pressurized common air chamber 35 and the negative pressure common air chamber 36, and controls the ink pump P1 and the air pump P2 to circulate the ink IK (step S1).

[0057] Next, the control unit 71 controls the rotation drive unit 21 to start rotating the inkjet head 10 to a landscape printing angle (step S2).

[0058] Next, the control unit 71 determines whether the inkjet head 10 has rotated to a landscape printing angle based on the detection results of the rotational position detection sensor 23 and the like (step S3).

[0059] 7, if the inkjet head 10 is in the middle of rotation and has not yet reached the landscape printing angle (step S3: NO), the control unit 71 controls the air pump P2 to adjust the pressure of the gas in the pressurized common air chamber 35 and the negative pressure common air chamber 36 (i.e., the gas in the pressurized tank 31 and the negative pressure tank 34) to a specified pressure (step S4). In this way, the control unit 71 may adjust the pressure of the gas in the pressurized tank 31 and the negative pressure tank 34 while the inkjet head 10 is rotating. Thereafter, the control unit 71 again performs the process of determining whether the inkjet head 10 has reached the landscape printing angle (step S3). Note that the control unit 71 may also control the air pump P2 to change the pressure of the gas in the pressurized common air chamber 35 and the negative pressure common air chamber 36 (for example, to increase the negative pressure continuously or in stages) depending on the rotation angle of the inkjet head 10. Furthermore, the gas pressure in the pressurized common air chamber 35 and the negative pressure common air chamber 36 that is changed by the control unit 71, i.e., the gas pressure in the pressurized tank 31 and the negative pressure tank 34, may be a specified pressure determined through experiments (if the pressure is changed, a specified pressure corresponding to the rotation angle of the inkjet head 10).

[0060] When the inkjet head 10 has rotated to the landscape printing angle as shown in FIG. 4 (step S3: YES), the control unit 71 controls the rotation drive unit 21 to stop the rotation of the inkjet head 10 (step S5).

[0061] Thereafter, the control unit 71 determines whether it is time to start printing (step S6), and if it is time to start printing (step S6: YES), it controls the inkjet head 10 to start printing (step S7), and ends the processing shown in FIG. 8.

[0062] On the other hand, if it is not the timing to start printing (step S6: NO), the control unit 71 controls the ink pump P1 and the air pump P2 to stop the circulation of the ink IK in order to reduce power consumption, and opens the air release valves 35a, 36a of the pressurized common air chamber 35 and the negative pressure common air chamber 36 (step S8). Then, the control unit 71 ends the process shown in Fig. 8. Note that the process of step S8 is similarly performed after the printing process of step S7 is completed.

[0063] 8, the atmospheric release valves 35a, 36a of the pressurized common air chamber 35 and the negative pressure common air chamber 36 are closed and the ink IK is circulated when the inkjet head 10 rotates from the downward standby angle to the horizontal printing angle. However, if the inkjet printing apparatus 1 does not include an ink circulation unit 30 (circulation flow path), for example, circulation of the ink IK is not necessary. Furthermore, the atmospheric release valves 35a, 36a of the pressurized common air chamber 35 and the negative pressure common air chamber 36 may also be closed when the inkjet head 10 rotates from the horizontal standby angle to the downward standby angle. In this way, the control unit 71 may close the atmospheric release valves 35a, 36a of the pressurized common air chamber 35 and the negative pressure common air chamber 36 at least one of when the inkjet head 10 rotates from the downward standby angle to the horizontal printing angle and when the inkjet head 10 rotates from the horizontal printing angle to the downward standby angle.

[0064] In the present embodiment described above, the inkjet printing device 1 includes an inkjet head 10 that ejects ink IK in a horizontal direction D2 that intersects the vertical direction, a rotation mechanism 20 that rotates the inkjet head 10 to a horizontal printing angle when printing and to a standby angle when not printing, an ink flow path connected to the inkjet head 10 and through which the ink IK flows, a pressurized tank 31 and a negative pressure tank 34 that are connected to the ink flow path and are examples of tanks that store the ink IK, atmosphere release valves 35a, 36a that release gas from the pressurized tank 31 and the negative pressure tank 34 to the atmosphere, and a control unit 71 that closes the atmosphere release valves 35a, 36a (step S1) when the inkjet head 10 is rotating (steps S2 to S5).

[0065] In this way, the control unit 71 closes the atmosphere release valves 35a, 36a when the inkjet head 10 is rotating, thereby sealing off the gas in the pressurized tank 31 and the negative pressure tank 34. Therefore, even if vibrations occur due to the rotation of the inkjet head 10, it is possible to make it difficult for pressure fluctuations in the ink IK to occur in the nozzles of the head module 11. This makes it possible to prevent damage to the meniscus of the ink IK in the nozzles of the head module 11. Therefore, according to this embodiment, it is possible to prevent ejection defects after rotation of the inkjet head 10 that ejects the ink IK in the lateral direction D2.

[0066] Furthermore, in this embodiment, the inkjet printing apparatus 1 includes an air pump P2, which is an example of a pressure adjusting unit that adjusts the gas pressure in the pressurized tank 31 and the negative pressure tank 34. The control unit 71 controls the air pump P2 so that the gas pressure in the pressurized tank 31 and the negative pressure tank 34 is set to a specified pressure when the inkjet head 10 is rotating.

[0067] This allows the pressure of the ink IK in the nozzles of the head module 11 to approach a pressure at which the meniscus is less likely to be destroyed. This makes it possible to more reliably prevent the meniscus of the ink IK from being destroyed in the nozzles of the head module 11. This makes it possible to further prevent ejection defects after the inkjet head 10 is rotated.

[0068] Furthermore, in this embodiment, the inkjet printing apparatus 1 is equipped with an air pump P2, which is an example of a pressure adjusting unit that adjusts the gas pressure in the pressurized tank 31 and the negative pressure tank 34. The ink flow path that is connected to the inkjet head 10 and through which the ink IK flows is a circulation flow path that includes a supply flow path (such as the supply tube 39a) through which the ink IK supplied to the inkjet head 10 flows, and a discharge flow path (such as the discharge tube 39b) through which the ink IK discharged from the inkjet head 10 flows, and the control unit 71 controls the air pump P2 so as to circulate the ink IK in the circulation path when the inkjet head 10 rotates.

[0069] Therefore, even if vibrations occur due to the rotation of the inkjet head 10, the circulation of the ink IK makes it even more difficult for pressure fluctuations of the ink IK to occur in the nozzles of the head module 11. This makes it possible to more reliably prevent the meniscus of the ink IK in the nozzles of the head module 11 from being destroyed. Therefore, ejection defects after the rotation of the inkjet head 10 can be further prevented.

[0070] The present invention is not limited to the above-described embodiment, and the components can be modified and embodied without departing from the spirit of the invention. Furthermore, various inventions can be formed by appropriately combining the multiple components disclosed in the above-described embodiment. For example, all the components shown in the embodiment can be appropriately combined. Naturally, various modifications and applications are possible without departing from the spirit of the invention. The invention as originally claimed in the present application is described below.

[0071] [Appendix 1] an inkjet head that ejects ink in a horizontal direction that intersects with the vertical direction; a rotation mechanism that rotates the inkjet head to a horizontal printing angle during printing and a standby angle during non-printing; an ink flow path connected to the inkjet head and through which ink flows; a tank connected to the ink flow path and configured to store ink; an atmosphere release valve that releases the gas in the tank to the atmosphere; a control unit that closes the atmosphere release valve when the inkjet head is rotating; An inkjet printing apparatus comprising:

[0072] [Appendix 2] Further provided is a pressure adjusting unit that adjusts the pressure of the gas in the tank, The control unit controls the pressure adjustment unit so that the gas pressure in the tank is kept at a specified pressure when the inkjet head is rotating. 2. The inkjet printing apparatus according to claim 1.

[0073] [Appendix 3] Further provided is a pressure adjusting unit that adjusts the pressure of the gas in the tank, the ink flow path is a circulation flow path including a supply flow path through which ink is supplied to the inkjet head and a discharge flow path through which ink is discharged from the inkjet head, The control unit controls the pressure adjustment unit to circulate ink in the circulation channel when the inkjet head rotates. 2. The inkjet printing apparatus according to claim 1. [Explanation of symbols]

[0074] 1. Inkjet printing device 10 Inkjet head 11 Head module 20 Rotation mechanism 21 Rotation drive unit 22 Rotating member 22a, 22b Notch 23 Rotational position detection sensor 30 Ink circulation section 31 Pressurized Tank 32 Distributor 33 Collector 34 Negative pressure tank 35 Pressurized common air chamber 35a Atmospheric release valve 35b Pressure sensor 36 Negative pressure common air chamber 36a Atmospheric release valve 36b Pressure sensor 37 Temperature adjustment section 38a, 38b, 38c Ink circulation pipe 39a Supply tube 39b Discharge tube 50 Ink supply unit 51 Ink cartridges 52 Ink refill valve 53 Ink supply pipe 60 Purge Tray 71 Control Unit 72 Memory section 73 Interface section 100 Conveyor D1 Conveying direction D2 Horizontal M Printing material P1 ink pump P2 Air Pump

Claims

1. an inkjet head that ejects ink in a horizontal direction that intersects the vertical direction; a rotation mechanism that rotates the inkjet head to a horizontal printing angle during printing and a standby angle during non-printing; an ink flow path connected to the inkjet head and through which ink flows; a tank connected to the ink flow path and configured to store ink; an atmosphere release valve that releases the gas in the tank to the atmosphere; a control unit that closes the atmosphere release valve before the inkjet head starts to rotate; a pressure adjusting unit that adjusts the gas pressure of the tank, the ink flow path is a circulation flow path including a supply flow path through which ink is supplied to the inkjet head and a discharge flow path through which ink is discharged from the inkjet head, The control unit controls the pressure adjustment unit to adjust the gas pressure in the tank to a specified pressure and to circulate ink in the circulation flow path so that a meniscus of ink in a nozzle of the inkjet head is not destroyed during rotation of the inkjet head with the atmosphere release valve closed.

1. An inkjet printing apparatus comprising:

Images