Ink supply system, inkjet printer and ink decompression method

Abstract

To provide an ink supply system that can reduce amounts of ink that is consumed in pressure cleaning.SOLUTION: An ink supply system 70 comprises a tube pump 74, a damper 76 and a control device 90. The control device 90 varies a pressed state and an opened state of a tube 74b provided in the tube pump 74. When the tube 74b is in the pressed state, the inside of the damper 76 is pressurized, so that pressure cleaning can be executed. Thereafter, the control device 90 varies the pressed state of the tube 74b into the opened state, so that the inside of the damper 76 is decompressed. This can decompress the inside of the damper 76, without consuming ink after the pressure cleaning.SELECTED DRAWING: Figure 7C

Description

[Technical field]

[0001] The present invention relates to an ink supply system, an inkjet printer, and an ink pressure reducing method. [Background technology]

[0002] Inkjet printers that eject ink have been known for some time. Patent Document 1 discloses an inkjet printer that includes a liquid container that contains ink, an ejection head that has a nozzle that ejects ink, a liquid flow path that connects the liquid container and the ejection head, a damper that is provided in the liquid flow path and has a storage chamber in which the ink is temporarily stored, and a liquid feed pump that is provided in the liquid flow path. The damper stores ink in the storage chamber to reduce pressure fluctuations of the ink and stabilize the ejection of the ink.

[0003] Some inkjet printers have a function of discharging ink from the nozzles to perform cleaning. One method is, for example, so-called pressurized cleaning, in which ink in a liquid flow path is pressurized to discharge the ink from the nozzles. Patent Document 1 discloses a pressurized cleaning method in which ink in a liquid flow path is pressurized by a liquid feed pump to discharge the ink from the nozzles. Pressurized cleaning is performed, for example, for the purpose of discharging air bubbles in the liquid flow path together with the ink. In addition, by applying pressure, it is possible to prevent inks that are mixed near the nozzles during cleaning from being sucked into the nozzles. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2020-199658 A Summary of the Invention [Problem to be solved by the invention]

[0005] When pressure cleaning is performed on such an inkjet printer, the ink inside the damper is pressurized. In order to return the ink from the pressurized state to a state where the ink is under a pressure that allows printing, it is necessary to reduce the pressure of the ink inside the damper. The reduction in pressure can be achieved, for example, by a method of sucking the ink using a suction pump, or by a method of ejecting ink from an ejection head, known as flushing.

[0006] However, ink is ejected from the ejection head by performing suction using a suction pump or flushing. In other words, ink needs to be consumed to reduce the pressure of the pressurized ink. The amount of ink consumed by pressurized cleaning is relatively large. This poses the problem of a large amount of ink being wasted.

[0007] The present invention has been made in consideration of the above points, and an object of the present invention is to provide an ink supply system that can reduce the amount of ink consumed during pressure cleaning. [Means for solving the problem]

[0008] The ink supply system of the present invention includes an ink tank containing ink, an ink head that ejects the ink, an ink supply path that communicates between the ink tank and the ink head, a damper provided in the ink supply path, a tube pump that is disposed in the ink supply path between the damper and the ink tank and sends the ink in a direction toward the ink head, and a control device that controls the tube pump. The tube pump includes an elastically deformable tube, and a pressing body that presses the tube to change the state between a pressed state in which the tube is deformed and an open state in which the tube is not deformed. The control device includes a pressurization control unit that changes the tube to the pressed state, thereby making the pressure inside the damper higher than the pressure when the ink head ejects the ink onto a printed material, and a decompression control unit that changes the tube to the open state after the pressurization control unit pressurizes the inside of the damper.

[0009] According to this ink supply system, the tube of the tube pump is changed to a pressed state by the pressurization control unit. As a result, ink on the ink tank side of the ink supply path is sent to the ink head side. That is, the ink head side of the ink supply path is pressurized by the tube pump, and the ink tank side of the ink supply path is depressurized by the tube pump. At this time, the pressure inside the damper is higher than the pressure when the ink head ejects the ink onto the printed material. Therefore, pressurized cleaning can be performed. After that, the depressurization control unit changes the tube of the tube pump to the open state. When the tube changes to the open state, no pressure difference occurs between the ink head side of the tube pump and the ink tank side of the tube pump. That is, the pressure inside the ink supply path becomes uniform. Therefore, the inside of the damper, which was pressurized, is depressurized. As a result, the inside of the damper can be depressurized without ejecting ink from the ink head. Effect of the Invention

[0010] According to the present invention, it is possible to provide an ink supply system that can reduce the amount of ink consumed during pressure cleaning. [Brief description of the drawings]

[0011] [Figure 1] 1 is a front view illustrating an inkjet printer according to an embodiment. [Diagram 2] FIG. 4 is a diagram illustrating a schematic configuration of the bottom surface of the carriage. [Diagram 3] FIG. 2 is a front view showing a schematic configuration of a cleaning unit. [Figure 4] FIG. 2 is a schematic diagram illustrating a configuration of an ink supply system. [Diagram 5] FIG. 2 is a block diagram of a control device according to an embodiment. [Figure 6] 10 is a flowchart showing a procedure for performing pressure cleaning and returning the pressure inside the damper to the discharge pressure. [Figure 7A] FIG. 2 illustrates the ink supply system when the tube is in an open state. [Figure 7B] 13A and 13B are diagrams illustrating the ink supply system when a pressing body presses a tube. [Figure 7C] FIG. 13 is a diagram showing the ink supply system when the pressing body is in the pressing end position. [Figure 7D] 13 is a diagram showing the ink supply system when the pressing body has moved further from the pressing end position. FIG. [Figure 8] FIG. 4 is a diagram showing changes in pressure inside a damper. [Figure 9] FIG. 11 is a block diagram of a control device according to another embodiment. [Figure 10A] FIG. 13 is a diagram showing an ink supply system in another embodiment when the tube is in a pressed state. [Figure 10B] FIG. 13 illustrates an ink supply system in another embodiment when the tube is in an open state. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0012] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. Note that the embodiment described here is not intended to limit the present invention in particular. In addition, the same reference numerals are used for members and parts that perform the same function, and duplicated descriptions are omitted or simplified as appropriate.

[0013] FIG. 1 is a front view of an inkjet printer 100 (hereinafter referred to as printer 100) according to this embodiment. In the following description, the symbols F, Rr, L, R, U, and D in the drawings respectively mean front, rear, left, right, top, and bottom when the printer 100 is viewed from the front. The symbol Y in the drawings indicates the main scanning direction, and the symbol X in the drawings (see FIG. 2) indicates the sub-scanning direction. In this embodiment, the main scanning direction Y is the left-right direction. The sub-scanning direction X is the front-rear direction, which is a direction perpendicular to the main scanning direction Y in a plan view. However, these directions are merely defined for the convenience of description, and do not limit the installation mode of the printer 100, nor limit the present invention.

[0014] The printer 100 prints on a recording medium 5. In this embodiment, the recording medium 5 is a roll of recording paper, or what is called roll paper. However, the recording medium 5 is not limited to a roll of recording paper. For example, the recording medium 5 may be a sheet or film made of resin such as polyvinyl chloride or polyester, a plate material, a fabric such as a woven fabric or a nonwoven fabric, or other medium, in addition to paper such as plain paper or inkjet printing paper.

[0015] 1, the printer 100 includes a printer body 10, an operation panel 12, a platen 13, a transport mechanism 20, a guide rail 15, a carriage 17, a head moving mechanism 30, a cleaning unit 60, and an ink supply system 70. As shown in FIG. 3, the cleaning unit 60 includes a wiper unit 61 and a cap unit 62.

[0016] As shown in FIG. 1, the printer body 10 has a casing 10a extending in the main scanning direction Y. The operation panel 12 is provided, for example, on the front right side of the printer body 10. However, the position of the operation panel 12 is not particularly limited. The operation panel 12 is used by the user to perform operations related to printing. Although not shown, the operation panel 12 is provided with a display unit that displays information related to printing, such as resolution and ink density, and the status of the printer 100 during printing, and an input unit for inputting information related to printing. The recording medium 5 is supported on the platen 13, and printing is performed on the platen 13. The platen 13 extends in the main scanning direction Y and the sub-scanning direction X.

[0017] The transport mechanism 20 transports the recording medium 5 supported by the platen 13 in the sub-scanning direction X. The configuration of the transport mechanism 20 is not particularly limited. In this embodiment, the transport mechanism 20 includes a pinch roller 21, a grit roller 22, and a feed motor 23. The pinch roller 21 is disposed above the platen 13 and below the guide rail 15, and presses the recording medium 5 from above. The grit roller 22 is provided on the platen 13 with its upper portion exposed upward from the platen 13. The grit roller 22 faces the pinch roller 21. The installation positions and the number of the pinch roller 21 and the grit roller 22 are not particularly limited. In this embodiment, as shown in FIG. 1, the pinch roller 21 and the grit roller 22 are disposed at the left end and the right end of the platen 13, respectively.

[0018] Here, the feed motor 23 is connected to the grit roller 22 arranged at the right end of the platen 13. When the feed motor 23 is driven with the recording medium 5 sandwiched between the pinch roller 21 and the grit roller 22, the grit roller 22 rotates. This causes the recording medium 5 to be transported in the sub-scanning direction X. Note that the feed motor 23 may also be connected to the grit roller 22 arranged at the left end of the platen 13.

[0019] The head moving mechanism 30 is a mechanism that moves the carriage 17 and the ink head 40 (see FIG. 2) in the main scanning direction Y. The configuration of the head moving mechanism 30 is not particularly limited. In this embodiment, the head moving mechanism 30 includes left and right pulleys 31a and 31b, a belt 32, and a carriage motor 33. The left pulley 31a is provided near the left end of the guide rail 15. The right pulley 31b is provided near the right end of the guide rail 15. The belt 32 is, for example, endless, and is wound around the left pulley 31a and the right pulley 31b. The carriage 17 is attached and fixed to the belt 32.

[0020] A carriage motor 33 is connected to the right pulley 31b. When the carriage motor 33 is driven, the right pulley 31b rotates and the belt 32 runs between the left and right pulleys 31a, 31b. This causes the carriage 17 and the ink head 40 to move in the main scanning direction Y along the guide rail 15.

[0021] FIG. 3 is a front view showing the cleaning unit 60. The cleaning unit 60 is configured to be able to clean the ink head 40 when the carriage 17 has moved to a predetermined cleaning position L1. As shown in FIG. 3, in this embodiment, the cleaning position L1 is near the right end of the guide rail 15. However, the location of the cleaning position L1 is not particularly limited. As shown in FIG. 3, the cleaning unit 60 includes a wiper unit 61 and a cap unit 62. The wiper unit 61 includes a wiper 61a and a wiper moving part 61b. The wiper 61a is configured in a flat plate shape extending in the main scanning direction Y and the up-down direction. The wiper 61a is made of, for example, rubber. The wiper moving part 61b moves the wiper 61a in the sub-scanning direction X and brings it into contact with the nozzle surface 42 (see FIG. 2) of the ink head 40, which will be described later. The nozzle surface 42 of the ink head 40 is wiped by the wiper 61a moving in the sub-scanning direction X. This is called a wiping process. The wiping process is one of the cleaning processes for cleaning the ink head 40. Note that the configuration of the wiper unit 61 is not limited to the above. Wiping may be performed, for example, by moving the carriage 17, or may be performed so as to proceed in the main scanning direction Y.

[0022] The cap unit 62 protects the ink head 40 and sucks ink from the nozzles 41 (see FIG. 2) of the ink head 40. The process of sucking ink from the nozzles 41 is called a suction process. The suction process is one of the cleaning processes. As shown in FIG. 3, the cap unit 62 includes a cap 62a, a cap moving section 62b, and a suction pump 62c. The cap 62a is configured to be attachable to the ink head 40. The cap moving section 62b moves the cap 62a in the vertical direction to attach or detach the cap 62a from the ink head 40. The suction pump 62c reduces the pressure inside the cap 62a while the cap 62a is attached to the ink head 40, thereby sucking ink from the nozzles 41. This executes the suction process. In addition, in the cleaning process, a process of ejecting ink from the ink head 40 toward the cap 62a while the cap 62a is detached is performed. This process is called a flushing process. The flushing process is one of the cleaning processes.

[0023] As shown in Fig. 1, the printer 100 includes an ink supply system 70. Fig. 4 is a schematic diagram of the ink supply system 70. As shown in Fig. 4, the ink supply system 70 includes an ink head 40, an ink tank 71, an ink supply path 72, an on-off valve 73, a tube pump 74, a damper 76, a pressure sensor 77, and a control device 90 (see Fig. 1). The ink supply system 70 supplies ink from the ink tank 71 to the ink head 40.

[0024] FIG. 2 is a diagram showing a schematic configuration of the lower surface of the carriage 17. As shown in FIG. 2, the ink head 40 is provided on the carriage 17. The ink head 40 is supported by the carriage 17 so that the lower surface of the ink head 40 is exposed below the carriage 17. The ink head 40 ejects ink. The number of ink heads 40 is not particularly limited, but in this embodiment, there are four ink heads. The four ink heads 40 are arranged side by side in the main scanning direction Y. The ink head 40 has a nozzle surface 42 in which nozzles 41 that eject ink are formed. The nozzle surface 42 forms the lower surface of the ink head 40 and faces the platen 13 (see FIG. 1). The nozzle surface 42 has a plurality of nozzles 41 arranged in the sub-scanning direction X. The nozzles 41 are minute holes that eject ink onto the recording medium 5 (see FIG. 1). The plurality of nozzles 41 form a nozzle row 41a arranged in the sub-scanning direction X. The nozzle 41 is connected to a pressure chamber (not shown) inside the ink head 40. The pressure chamber contains ink. By maintaining an appropriate pressure in the pressure chamber, a meniscus is formed in the nozzle 41, and the ink head 40 becomes ready for printing. There is no particular limitation on the method for ejecting ink, but for example, ink is ejected using an actuator (not shown) formed of a piezoelectric element. The actuator is connected to the pressure chamber. Therefore, ink is ejected from the nozzle 41 by driving the actuator to expand / contract the pressure chamber.

[0025] As shown in FIG. 4, the ink tank 71 is a container in which ink is stored. In this embodiment, the ink tank 71 is an ink cartridge. However, the ink tank 71 is not limited to an ink cartridge. In this embodiment, the ink tank 71 is disposed above the ink head 40. Therefore, the ink stored in the ink tank 71 moves to the ink head 40 due to a head difference. The ink tank 71 may be, for example, a pouch-shaped one. The ink tank 71 stores, for example, one of a process color ink and a special color ink (for example, a white ink, a clear ink, etc.). However, the color of the ink stored in the ink tank 71 is not particularly limited. In addition, the material of the ink is not limited at all, and various materials that have been conventionally used as ink materials for inkjet printers can be used. The ink may be, for example, a solvent-based pigment ink or a water-based pigment ink. Alternatively, the ink may be a water-based dye ink or an ultraviolet-curable pigment ink that is cured by receiving ultraviolet light.

[0026] The ink supply path 72 is a flow path to which the ink tank 71 is connected. The ink supply path 72 is connected to the nozzle 41 of the ink head 40. The ink supply path 72 guides the ink contained in the ink tank 71 to the nozzle 41. Here, regarding the flow of ink in the ink supply path 72, the ink tank 71 side is referred to as the upstream side, and the nozzle 41 side is referred to as the downstream side. The ink supply path 72 is formed, for example, by a flexible tube. In this embodiment, the ink supply path 72 includes a first ink supply path 72a, a second ink supply path 72b, and a third ink supply path 72c. The first ink supply path 72a is a flow path that connects the ink tank 71 and the on-off valve 73. The second ink supply path 72b is a flow path that connects the on-off valve 73 and the tube pump 74. The third ink supply path 72c is a flow path that connects the tube pump 74 and the damper 76. Although not shown in the drawings, the ink supply path 72 is provided with a damper 76 and a separate circuit for refilling ink inside the ink head 40. The ink supply path 72 may be provided with a circulation path for causing ink on the downstream side to flow to the upstream side.

[0027] The on-off valve 73 is disposed downstream of the ink tank 71 between the ink tank 71 and the tube pump 74. The on-off valve 73 is configured to be able to open or close the ink supply path 72. More specifically, the on-off valve 73 is configured to be able to communicate or block the first ink supply path 72a and the second ink supply path 72b. Here, "the on-off valve 73 opens the ink supply path 72" includes the case where the on-off valve 73 completely opens the ink supply path 72 and the case where the on-off valve 73 partially opens the ink supply path 72. When the on-off valve 73 is opened, the first ink supply path 72a and the second ink supply path 72b are connected. At this time, the ink stored in the ink tank 71 can be led to the nozzle 41. When the on-off valve 73 is closed, the first ink supply path 72a and the second ink supply path 72b are blocked. The on-off valve 73 is electrically connected to a control device 90 (see FIG. 5) and is controlled by the control device 90. The on-off valve 73 is, for example, an electromagnetic valve.

[0028] The tube pump 74 is disposed between the on-off valve 73 and the damper 76 in the ink supply passage 72. That is, the tube pump 74 is connected to the second ink supply passage 72b and the third ink supply passage 72c. The tube pump 74 is a pump for adjusting the pressure inside the damper 76 to adjust the pressure suitable for the ejection of ink by the ink head 40. The tube pump 74 includes a main body case 74a formed in an arc shape, a tube 74b disposed in the main body case 74a, a pressing body 74c capable of pressing a part of the tube 74b, a support portion 74d supporting the pressing body 74c, and a rotating portion 74e for rotating the pressing body 74c and the support portion 74d.

[0029] The tube 74b is formed so that ink passes through it and is elastically deformable. The tube 74b is arranged along the inner wall of the main body case 74a. Both ends of the tube 74b are arranged outside the main body case 74a. One end of the tube 74b is connected to the second ink supply path 72b, and the other end of the tube 74b is connected to the third ink supply path 72c. That is, the ink that flows from the second ink supply path 72b into the tube 74b is made to flow into the third ink supply path 72c. The tube 74b is pressed toward the radially outer side of the main body case 74a by the pressing body 74c.

[0030] The pressing body 74c is a member that presses the tube 74b toward the radial outside of the main body case 74a. The pressing body 74c is configured to be rotatable in the same direction as the rotating part 74e by rotating in the direction of the arrow D1. When the pressing body 74c rotates one revolution, the position where the pressing body 74c starts to press the tube 74b and deform the tube 74b is referred to as the pressing start position CP. The pressing body 74c is configured to send the ink in the tube 74b toward the ink head 40 by further rotating from the pressing start position CP. As a result, the upstream side of the tube pump 74 is depressurized and the downstream side of the tube pump 74 is pressurized. The pressing body 74c presses the tube 74b to a position rotated 180 degrees in the direction of the arrow D1 from the pressing start position CP. The position rotated 180 degrees in the direction of the arrow D1 from the pressing start position CP is referred to as the pressing end position EP. When the pressing body 74c moves further from the pressing end position EP in the direction of the arrow D1, the pressing body 74c moves away from the tube 74b. Note that "the pressing body 74c moves away from the tube 74b" includes a state in which the pressing body 74c is not in contact with the tube 74b and a state in which the pressing body 74c is in contact with the tube 74b but is not pressing the tube 74b (i.e., the tube 74b is not deformed). Here, the state of the tube 74b from when the pressing body 74c moves from the pressing start position CP toward the pressing end position EP, that is, the state in which the tube 74b is pressed, is referred to as the pressed state. Also, the state of the tube 74b from when the pressing body 74c passes through the pressing end position EP until when it moves toward the pressing start position CP, that is, the state in which the tube 74b is not deformed, is referred to as the released state. Therefore, the pressing body 74c changes the tube 74b between the pressed state and the released state. In this embodiment, the position rotated 180 degrees in the direction of the arrow D1 from the pressing start position CP is set as the pressing end position EP, but the positional relationship between the pressing start position CP and the pressing end position EP is not limited to this.

[0031] The support portion 74d is a member connected to the rotating portion 74e and supporting the pressing body 74c. Since the support portion 74d is connected to the rotating portion 74e, it rotates together with the rotation of the rotating portion 74e. Since the support portion 74d supports the pressing body 74c, the pressing body 74c can rotate together with the rotating portion 74e.

[0032] The rotating part 74e is connected to one end of the support part 74d in the longitudinal direction. The rotating part 74e rotates in the direction of the arrow D1. The configuration of the rotating part 74e is not particularly limited, but for example, it is a drive shaft connected to a motor. Since the rotating part 74e and the support part 74d are connected and the support part 74d and the pressing body 74c are connected, the pressing body 74c can be rotated by the rotation of the rotating part 74e. The rotating part 74e is electrically connected to a control device 90 (see FIG. 5) and is controlled by the control device 90.

[0033] The damper 76 reduces pressure fluctuations of the ink passing through the ink supply passage 72, stabilizing the ejection of ink from the ink head 40. For example, the drive of the tube pump 74 is controlled according to the pressure inside the damper 76. Here, the damper 76 is provided in the ink supply passage 72 and communicates with the ink head 40. In this embodiment, the damper 76 is disposed on the upper part of the ink head 40. The configuration of the damper 76 is not particularly limited. For example, the damper 76 has an ink chamber in which ink is temporarily stored. Although not shown in the figure, a part of the wall of the ink chamber is formed by an elastic film, and expands and contracts according to the amount of ink.

[0034] The pressure sensor 77 detects the pressure inside the damper 76. Here, "the pressure inside the damper 76" means the pressure of the ink inside the ink chamber that constitutes the damper 76. The pressure sensor 77 is, for example, a sensor that directly measures the magnitude of the pressure of the ink inside the damper 76 by an electric signal. The electric signal is transmitted to the control device 90. The pressure sensor 77 may also detect the pressure inside the damper 76 based on the size of the ink chamber of the damper 76 (for example, the degree of expansion and contraction).

[0035] As shown in FIG. 5, the control device 90 is a device that performs control related to printing. The configuration of the control device 90 is not particularly limited. The control device 90 is, for example, a microcomputer. The hardware configuration of the microcomputer is not particularly limited, but includes, for example, an interface (I / F) that receives print data and the like from an external device such as a host computer, a central processing unit (CPU) that executes instructions of a control program, a read only memory (ROM) that stores the program executed by the CPU, a random access memory (RAM) used as a working area for expanding the program, and a storage device such as a memory that stores the above program and various data. The control device 90 does not necessarily have to be provided inside the printer 100. For example, it may be a computer that is installed outside the printer 100 and is connected to the printer 100 so as to be able to communicate with it via wire or wirelessly.

[0036] In this embodiment, the control device 90 is communicatively connected to the tube pump 74. The control device 90 drives the tube pump 74. More specifically, the control device 90 controls the rotation of the rotating portion 74e of the tube pump 74.

[0037] In this embodiment, the control device 90 includes a pressurization control unit 91, a depressurization control unit 92, a first on-off valve control unit 93, a cleaning control unit 94, a pressure acquisition unit 95, and a state determination unit 96. Each unit of the control device 90 may be configured by software or by hardware. Each unit of the control device 90 may be executed by a processor or may be incorporated into a circuit. When executed by a processor, the number of processors may be one or more.

[0038] The pressurization control unit 91 rotates the rotating unit 74e of the tube pump 74 (see FIG. 4) to rotate the pressing body 74c. This puts the tube 74b (see FIG. 4) in a pressing state, and controls the pressure inside the damper 76 to the pressure during pressurized cleaning. The pressure during pressurized cleaning is a pressure higher than the pressure inside the damper 76 when the ink head 40 ejects ink onto the recording medium 5 (see FIG. 1). Here, the pressure inside the damper 76 when the ink head 40 ejects ink onto the recording medium 5 (see FIG. 1) is referred to as the ejection pressure. The ejection pressure is, for example, about -1.0 kPa. The pressure during pressurized cleaning is, for example, a pressure at which the meniscus formed in the nozzle 41 (see FIG. 2) bulges out of the nozzle 41, or a pressure at which the meniscus breaks. At this time, ink seeps out of the nozzle 41. The pressure at this time is, for example, about 3.0 kPa. The pressurization control unit 91 first rotates the rotating unit 74e (see FIG. 4) in the direction of the arrow D1 to place the pressing body 74c (see FIG. 4) at the pressing start position CP. After that, the pressing body 74c is further rotated in the direction of the arrow D1 to send the ink inside the tube 74b to the downstream side of the ink supply system 70. At this time, the inside of the damper 76 is pressurized. Note that in this embodiment, the amount of rotation of the rotating unit 74e after the tube 74b is in the pressing state is less than one rotation. In this embodiment, the pressing end position EP is located at a position rotated 180 degrees from the pressing start position CP. That is, the pressurization control unit 91 in this embodiment is configured to rotate the pressing body 74c 180 degrees from the state in which the pressing body 74c is placed at the pressing start position CP.

[0039] The pressure reduction control unit 92 changes the tube 74b to an open state after the pressurization control unit 91 pressurizes the inside of the damper 76. In this embodiment, when the control by the pressurization control unit 91 is executed, the pressing body 74c is placed at the pressing end position EP (see FIG. 4). The pressure reduction control unit 92 further rotates the rotating unit 74e from this state to rotate the pressing body 74c. The amount by which the pressure reduction control unit 92 rotates the pressing body 74c is less than 180 degrees. In other words, the pressure reduction control unit 92 rotates the pressing body 74c so that the tube 74b is in an open state. At this time, the ink that was pressurized on the downstream side of the tube pump 74 is depressurized.

[0040] The first on-off valve control unit 93 closes the on-off valve 73 before the tube 74b is in a pressed state by the pressurization control unit 91, and opens the on-off valve 73 after the tube 74b is in an open state by the depressurization control unit 92. That is, the first on-off valve control unit 93 closes the on-off valve 73 when the tube 74b is in an open state before the control by the pressurization control unit 91. Also, the first on-off valve control unit 93 opens the on-off valve 73 when the tube 74b is in an open state after the control by the depressurization control unit 92.

[0041] The cleaning control unit 94 performs cleaning of the ink head 40 in a state where the pressure inside the damper 76 is increased by the pressure control unit 91. That is, pressure cleaning is performed by the cleaning control unit 94. The cleaning control unit 94 performs each process in the order of, for example, the flushing process, the suction process, and the wiping process. However, the cleaning control unit 94 may perform any one or two of the above-mentioned processes. In addition, the order in which the cleaning control unit 94 performs each process is not particularly limited.

[0042] The pressure acquisition unit 95 acquires the measurement value measured by the pressure sensor 77. More specifically, the measurement value of the pressure sensor 77 is acquired by acquiring an electrical signal transmitted by the pressure sensor 77 when the pressure sensor 77 performs measurement.

[0043] The state determination unit 96 determines whether the tube 74b is in a pressed state or an open state based on the measured value acquired by the pressure acquisition unit 95. In this embodiment, the state determination unit 96 performs the determination based on whether the measured value of the pressure sensor 77 is equal to or less than the threshold value Pc. If the measured value exceeds the threshold value Pc, the state determination unit 96 determines that the tube 74b is in a pressed state. If the measured value is equal to or less than the threshold value Pc, the state determination unit 96 determines that the tube 74b is in an open state. Note that the threshold value Pc is, for example, the maximum value among the theoretical values ​​of the pressure inside the ink supply path 72 when the tube 74b is in an open state. When the decompression by the decompression control unit 92 is completed, if the measured value is equal to or less than the threshold value Pc, the state determination unit 96 may be configured to display, for example, on the operation panel 12 that the decompression is completed. Also, when the control by the decompression control unit 92 is completed, if the measured value exceeds the threshold value Pc, the state determination unit 96 may be configured to display, for example, an error on the operation panel 12.

[0044] Next, an operation of returning the pressure inside the damper 76 to the discharge pressure after performing the pressurized cleaning will be described. FIG. 6 is a flowchart illustrating a procedure for performing the pressurized cleaning and then returning the pressure inside the damper 76 to the discharge pressure. FIGS. 7A to 7D are schematic diagrams illustrating the operation of the tube pump 74 during execution of the flowchart shown in FIG. 6. In addition, in FIGS. 7A to 7C, the "x" of the opening and closing valve 73 indicates that the opening and closing valve 73 is closed. In the following description, the pressure inside the third ink supply passage 72c and the pressure inside the damper 76 are assumed to be the same. FIG. 8 is a graph showing the change in the pressure inside the third ink supply passage 72c, that is, the pressure inside the damper 76, during execution of the flowchart in FIG. 6. In the graph in FIG. 8, the vertical axis indicates pressure and the horizontal axis indicates time. In addition, in the graph in FIG. 8, the slope during the pressure change and the time during which the pressure is constant are merely examples and may be changed as appropriate. Here, before the start of the flowchart shown in FIG. 6, the tube 74b is in an open state. Before the flow chart starts, the pressure of the ink inside the ink supply path 72 is the ejection pressure. The magnitude of the pressure at the ejection pressure is pressure P1. Before the flow chart starts, the first ink supply path 72a, the second ink supply path 72b, and the third ink supply path 72c are all at pressure P1, which is a uniform pressure.

[0045] In step S101, as shown in Fig. 7A, when the tube 74b is in an open state, the first on-off valve control unit 93 (see Fig. 5) closes the on-off valve 73. In step S101, as shown in Fig. 8, the pressure of the ink inside the third ink supply path 72c is P1. At this time, the pressure inside the first ink supply path 72a and the second ink supply path 72b is also P1.

[0046] In step S102 shown in FIG. 6, the pressure control unit 91 pressurizes the inside of the damper 76 by changing the pressing state of the tube 74b. The pressure control unit 91 rotates the rotating part 74e to move the pressing body 74c to the pressing start position CP shown in FIG. 7B. Then, the pressure control unit 91 rotates the rotating part 74e by 180 degrees and rotationally moves the pressing body 74c to the pressing end position EP. At this time, the pressing body 74c moves while crushing the tube 74b. The second ink supply path 72b is depressurized, and the third ink supply path 72c is pressurized. That is, the inside of the damper 76 is pressurized. Let the pressure inside the second ink supply path 72b at this time be P2 (<P1). Also, as shown in FIG. 8, let the pressure inside the third ink supply path 72c be P3 (>P1). The pressure P3 is a pressure such that the meniscus formed in the nozzle 41 protrudes outside the nozzle 41, or a pressure at which the meniscus breaks, and is, for example, about 3.0 kPa. Since the on-off valve 73 is closed, the pressure inside the first ink supply path 72a remains at P1. Also, at this time, the pressure sensor 77 measures the pressure P3, and the state determination unit 96 determines that the tube 74b is in a pressed state.

[0047] In step S103 shown in FIG. 6, the cleaning control unit 94 executes cleaning of the ink head 40 by performing a flushing process, a suction process, and a wiping process. That is, pressure cleaning is executed in step S103. When pressure cleaning is executed, ink oozes out from the nozzle 41. As a result, the pressure inside the third ink supply path 72c decreases. Let the pressure inside the third ink supply path 72c at this time be P4. As shown in FIG. 8, the pressure P4 is lower than the pressure P3. However, the pressure P4 is higher than the pressures P1 and P2. Cleaning of the ink head 40 is executed at the cleaning position L1 (see FIG. 3).

[0048] In step S104 shown in FIG. 6, the pressure reduction control unit 92 reduces the pressure inside the damper 76 by changing the tube 74b to an open state. As shown in FIG. 7C, the pressure reduction control unit 92 (see FIG. 5) rotates the rotating unit 74e to rotate the pressing body 74c from the pressing end position EP. This causes the tube 74b to be in an open state. At this time, the pressure inside the second ink supply path 72b increases from P2, and the pressure inside the third ink supply path 72c decreases from P4. Eventually, the pressure inside the second ink supply path 72b and the third ink supply path 72c becomes uniform. The pressure at this time is P5. Here, as described above, in step S103, ink seeps out from the nozzle 41, and the pressure inside the third ink supply path 72c decreases. Therefore, as shown in FIG. 8, the pressure P5 is lower than the pressure P1. As shown in FIG. 7C, since the on-off valve 73 is closed, the pressure inside the first ink supply path 72a remains at P1.

[0049] In step S105 shown in FIG. 6, the first on-off valve control unit 93 opens the on-off valve 73. Therefore, as shown in FIG. 7D, the first ink supply path 72a, the second ink supply path 72b, and the third ink supply path 72c are connected. Here, the pressure P1 inside the first ink supply path 72a is higher than the pressure P5 inside the second ink supply path 72b and the third ink supply path 72c. In addition, the ink tank 71 is disposed above the ink head 40. Therefore, the first ink supply path 72a is disposed above the second ink supply path 72b and the third ink supply path 72c. At this time, the pressure inside the second ink supply path 72b and the third ink supply path 72c increases due to the head difference. The pressure inside the third ink supply path 72c at this time is P6. As shown in FIG. 8, the pressure P6 is higher than the pressure P5 and lower than the pressure P1.

[0050] In step S106, the state determination unit 96 determines whether the measurement value of the pressure sensor 77 is equal to or lower than the threshold value Pc. That is, the state determination unit 96 checks whether P6≦Pc is satisfied for the pressure P6 and the threshold value Pc. When P6≦Pc is satisfied, the state determination unit 96 displays on the operation panel 12 that the pressure reduction is complete. When P6>Pc is satisfied, the state determination unit 96 displays an error on the operation panel 12. Note that there are cases where the pressure P6 is lower than the ejection pressure. In this case, the pressure inside the damper 76 may be increased to the ejection pressure using a circuit for refilling the damper 76 and the ink head 40 with ink.

[0051] As described above, according to the ink supply system 70 of the present embodiment, the tube 74b of the tube pump 74 is changed to a pressed state by the pressurization control unit 91. The pressing body 74c moves from the pressing start position CP to the pressing end position EP while squashing the tube 74b. As a result, the ink in the tube 74b is sent to the third ink supply path 72c. The third ink supply path 72c is pressurized, and the second ink supply path 72b is depressurized. At this time, the pressure inside the damper 76 is higher than the discharge pressure. Therefore, it is possible to perform pressurized cleaning. After that, the tube 74b of the tube pump 74 is changed to an open state by the depressurization control unit 92. When the tube 74b is changed to an open state, the tube 74b is no longer pressed. Therefore, the pressure inside the third ink supply path 72c decreases, and the pressure inside the second ink supply path 72b increases. As a result, the pressure inside the damper 76 can be depressurized without discharging ink from the ink head 40. According to this embodiment, there is no need to eject ink in order to return the pressure inside the damper 76 to the ejection pressure. There is no need to eject ink before starting printing after performing pressurized cleaning. Therefore, it is possible to reduce unnecessary consumption of ink.

[0052] According to the ink supply system 70 of this embodiment, the on-off valve 73 is disposed between the ink tank 71 and the tube pump 74. That is, the on-off valve 73 is configured to allow the first ink supply path 72a and the second ink supply path 72b to communicate with each other or to be blocked. The first on-off valve control unit 93 closes the on-off valve 73 before the tube 74b is pressed by the pressurization control unit 91. As a result, when the tube 74b is pressed and the second ink supply path 72b is depressurized to pressure P2, the pressure inside the first ink supply path 72a remains at P1. In addition, the first on-off valve control unit 93 opens the on-off valve 73 after the tube 74b is opened by the depressurization control unit 92. When the tube 74b is opened by the depressurization control unit 92, the pressures in the second ink supply path 72b and the third ink supply path 72c are both pressure P5. The pressure P5 is lower than the pressure P1 due to the seepage of ink when the inside of the damper 76 is pressurized. By opening the on-off valve 73, the pressure in the second ink supply path 72b and the third ink supply path 72c, which had been at pressure P5, increases to P6. Therefore, it is possible to compensate for a part of the pressure loss caused by the seepage of ink during pressurization.

[0053] According to the ink supply system 70 of this embodiment, the pressure sensor 77 measures the pressure inside the damper 76. The pressure acquisition unit 95 acquires the measured value of the pressure sensor 77. The state determination unit 96 judges whether the tube 74b is in a pressed state or an open state depending on whether the measured value acquired by the pressure acquisition unit 95 exceeds the threshold value Pc. In order to judge whether the tube 74b of the tube pump 74 is in a pressed state or an open state, for example, there is a method of providing a position sensor that detects the position of the pressing body 74c. However, as in this embodiment, by judging the state of the tube 74b based on the measured value of the pressure sensor 77, it is possible to grasp the state of the tube 74b without providing a position sensor. Therefore, it is possible to suppress an increase in the number of parts constituting the ink supply system 70.

[0054] According to the ink supply system 70 of this embodiment, the tube pump 74 includes a support portion 74d and a rotating portion 74e. The pressurization control portion 91 is configured to rotate the rotating portion 74e 180 degrees after the state determination portion 96 determines that the tube 74b is in a pressed state. That is, the pressing body 74c moves so as to rotate 180 degrees while pressing the tube 74b from the pressing start position CP. Since the amount of rotation of the rotating portion 74e is 180 degrees, which is less than one rotation, the tube 74b remains in a pressed state during the control by the pressurization control portion 91. When the tube 74b is in an open state while the inside of the damper 76 is being pressurized by the pressurization control portion 91, the inside of the damper 76 is decompressed. Therefore, at this time, it is necessary to prevent a decrease in the pressure inside the damper 76. For example, by opening the opening / closing valve 73 while the tube 74b is in an open state, a decrease in the pressure inside the damper 76 can be prevented. However, in this case, the number of times the opening / closing valve 73 is opened and closed increases, making the control complicated. In the case where the rotating portion 74e rotates less than one rotation as in this embodiment, the control of the on-off valve 73 can be simplified.

[0055] The printer 100 of this embodiment is provided with a cleaning unit 60. The cleaning unit 60 includes a wiper unit 61 and a cap unit 62. This allows the printer 100 to perform flushing, suction, and wiping processes. Therefore, more processes can be performed in pressurized cleaning, improving the cleaning effect.

[0056] Although a preferred embodiment has been described above, the inkjet printer of the present invention is not limited to the above embodiment.

[0057] In the above-described embodiment, ink is moved by using the head difference between the ink tank 71 and the ink head 40. Therefore, the ink supply path 72 is provided with a damper 76 and a separate circuit for refilling ink inside the ink head 40, but is not limited to this. The ink tank 71 may be disposed below the ink head 40. In this case, as shown in FIG. 9, the control device 90A may include a second opening / closing valve control unit 97. Note that the control device 90A has the same configuration as the control device 90 shown in FIG. 5 except for the second opening / closing valve control unit 97, and therefore description thereof will be omitted.

[0058] The second on-off valve control unit 97 opens the on-off valve 73 when the tube 74b is in a pressed state and closes the on-off valve 73 when the tube 74b is in an open state when control is not being performed by the first on-off valve control unit 93. For example, the second on-off valve control unit 97 controls the on-off valve 73 when refilling the ink head 40 and the damper 76 with ink. FIGS. 10A and 10B are schematic diagrams of the ink supply system 70 when refilling the ink head 40 and the damper 76 with ink. In addition, in FIGS. 10A and 10B, the ink tank 71 is disposed below the ink head 40. As shown in FIG. 10A, when the tube 74b is in a pressed state, the second on-off valve control unit 97 (see FIG. 9) opens the on-off valve 73. As a result, the ink in the ink tank 71 is sent to the ink head 40 and the damper 76. Also, as shown in FIG. 10B, when the tube 74b is in an open state, the second on-off valve control unit 97 closes the on-off valve 73. When the tube 74b is in a pressed state, the downstream side of the tube pump 74 is pressurized. Therefore, when the tube 74b changes from a pressed state to an open state, there is a possibility that the ink inside the ink head 40 and the damper 76 will flow back to the ink tank 71. However, since the on-off valve 73 is closed when the tube 74b is in an open state, it is possible to prevent backflow to the ink tank 71. Therefore, by providing the second on-off valve control unit 97, the tube pump 74 can also be used as a liquid feed pump that refills the ink head 40 and the damper 76 with ink. Therefore, there is no need to provide a separate liquid feed pump, and an increase in the number of parts of the ink supply system 70 can be suppressed. In addition, at this time, the positional relationship between the ink tank 71 and the ink head 40 in the vertical direction is not limited.

[0059] The technology disclosed herein can be applied to various types of printers. In addition to the roll-to-roll type printer described in the above embodiment, the technology can also be applied to so-called flatbed type printers in which a recording medium is fixed on a table and printing is performed by transporting the table. The technology can also be applied to so-called gantry type printers in which a recording medium is placed on a table and printing is performed by moving a carriage relative to the table in the main scanning direction Y and in the front-rear direction. [Explanation of symbols]

[0060] 40 Ink Head 41 Nozzle 42 Nozzle surface 70 Ink supply system 71 Ink tank 72 Ink supply path 74 Tube Pump 74b tube 74c Pressing body 90 Control device 91 Pressure control section 92 Pressure reduction control section

Claims

1. an ink tank containing ink; an ink head that ejects the ink; and an ink supply path that connects the ink tank and the ink head; a damper provided in the ink supply path; a tube pump disposed in the ink supply path between the damper and the ink tank, the tube pump feeding the ink in a direction toward the ink head; A control device for controlling the tube pump, The tube pump comprises: An elastically deformable tube; a pressing body that changes the state between a pressing state in which the tube is pressed to deform the tube and an open state in which the tube is not deformed; The control device includes: a pressure control unit that changes the tube to the pressed state to make the pressure inside the damper higher than the pressure when the ink head ejects the ink onto a printed material; a pressure reduction control unit that changes the tube to the open state after the inside of the damper is pressurized by the pressurization control unit.

2. an opening / closing valve disposed between the ink tank and the tube pump in the ink supply path, the opening / closing valve opening / closing the ink supply path; The ink supply system of claim 1, wherein the control device includes a first valve control unit that closes the valve before the tube is pressed by the pressurization control unit, and opens the valve after the tube is placed in the open state by the decompression control unit.

3. The ink supply system of claim 2, wherein the control device is provided with a second valve control unit that opens the valve when the tube is in the pressed state and closes the valve when the tube is in the open state when control is not being performed by the first valve control unit.

4. a pressure sensor connected to the damper for measuring a pressure inside the damper; The control device includes: a pressure acquisition unit that acquires a measurement value of the pressure sensor; The ink supply system according to claim 1 , further comprising: a state determination unit that determines whether the tube is in the pressed state or the tube is in an open state based on the measured value acquired by the pressure acquisition unit.

5. The tube pump comprises: A support portion that supports the pressing body; A rotating unit that rotates the support unit, the pressurization control unit rotates the rotating unit by a predetermined rotation amount after the state determination unit determines that the tube is in the pressed state, The ink supply system according to claim 4 , wherein the predetermined amount of rotation is an amount of rotation that is less than one rotation.

6. An inkjet printer comprising the ink supply system according to any one of claims 1 to 5.

7. the ink head includes a nozzle surface on which nozzles for ejecting the ink are formed, a wiper unit including a wiper that wipes the nozzle surface and a wiper movement section that moves the wiper or the ink head while keeping the wiper in contact with the nozzle surface; 7. The inkjet printer according to claim 6, further comprising a cleaning unit including at least one of a cap unit having a cap attached to the ink head so as to cover the nozzles, a cap moving unit which attaches and removes the cap from the ink head, and a suction pump connected to the cap.

8. 1. An ink decompression method for decompressing an inside of a damper disposed in an ink supply path connected to an ink head, the method comprising the steps of: disposing a tube pump having an elastically deformable tube and a pressing body for changing a state between a pressed state in which the tube is pressed to deform the tube and an open state in which the tube is not deformed; a pressurizing step of pressing the tube of the tube pump to make the pressure inside the damper higher than the pressure when the ink head ejects ink onto a printed material; and a depressurizing step of opening the tube after pressurizing the inside of the damper in the pressurizing step.

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