Inkjet printer

Abstract

To provide an inkjet printer that can reduce amounts of ink that is consumed in pressure cleaning.SOLUTION: A printer 100 comprises an ink head 40, a damper 76, a liquid feeding pump 74 and an electromagnetic switching valve 75. The electromagnetic switching valve 75 comprises an ink storage part 751c that can vary in volume. When pressure cleaning is executed, the liquid feeding pump 74 pressurizes the inside of the damper 76. After the pressure cleaning, volumes of the ink storage part 751c of the electromagnetic switching valve 75 are varied to decompress the inside of the damper 76. This can decompress the inside of the damper 76, without consuming ink after the pressure cleaning.SELECTED DRAWING: Figure 4

Description

[Technical field]

[0001] The present invention relates to inkjet printers. [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 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. [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 view of the above-mentioned points, and an object of the present invention is to provide an inkjet printer capable of reducing the amount of ink consumed during pressure cleaning. [Means for solving the problem]

[0008] The inkjet printer of the present invention comprises an ink tank containing ink, an ink head for ejecting the ink, an ink supply path connecting the ink tank and the ink head, a damper provided in the ink supply path, a liquid feed pump arranged in the ink supply path between the damper and the ink tank for feeding the ink in a direction toward the ink head, and an auxiliary container arranged in the ink supply path between the liquid feed pump and the damper. The auxiliary container comprises an ink storage section for storing the ink and configured to be volumetrically variable.

[0009] According to this inkjet printer, the ink stored in the ink tank passes through the ink supply path and the damper and is sent to the ink head by driving the liquid feed pump. The pressure inside the damper is set to a pressure corresponding to the driving of the liquid feed pump. When performing pressurized cleaning, the pressure inside the damper is higher than that during printing. At this time, the volume of the auxiliary container is changed to reduce the pressure inside the damper to a pressure at which printing is possible. Therefore, the pressure inside the damper can be reduced without ejecting the ink. Effect of the Invention

[0010] According to the present invention, it is possible to provide an inkjet printer capable of reducing 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] FIG. [Figure 7] FIG. 2 is a cross-sectional view of the solenoid switching valve in a first state. [Figure 8] FIG. 4 is a cross-sectional view of the solenoid switching valve in a second state. [Figure 9] FIG. 9 is an enlarged view of the main body portion in FIG. 8. [Figure 10] 10 is a flowchart showing a procedure for performing pressure cleaning and returning the pressure inside the damper to the discharge pressure. 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] As shown in FIG. 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, an ink head 40 (see FIG. 2), a cleaning unit 60, an ink supply unit 70, and a control device 90. The operation panel 12 is provided, for example, on the front of the 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 a user to perform operations related to printing. Although not shown, the operation panel 12 includes 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. As shown in FIG. 3, the cleaning unit 60 includes a wiper unit 61 and a cap unit 62.

[0016] 1, the printer body 10 has a casing 10a extending in the main scanning direction Y. A recording medium 5 is supported on a 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 respective 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. 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.

[0022] 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 is moved to a predetermined cleaning position P1. As shown in FIG. 3, in this embodiment, the cleaning position P1 is near the right end of the guide rail 15. However, the location of the cleaning position P1 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. 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.

[0023] 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.

[0024] As shown in Fig. 1, the printer 100 includes an ink supply unit 70. The ink supply unit 70 supplies ink to the ink head 40 (see Fig. 2). Fig. 4 is a schematic diagram of the ink supply unit 70. As shown in Fig. 4, the ink supply unit 70 includes an ink tank 71, an ink supply path 72, an on-off valve 73, a liquid feed pump 74, an electromagnetic switching valve 75, a damper 76, and a pressure sensor 77.

[0025] 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. 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, white ink, 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 used as ink materials for inkjet printers in the past 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 communicates with the nozzles 41 of the ink head 40. The ink supply path 72 guides the ink contained in the ink tank 71 to the nozzles 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. Note that the ink supply path 72 may include a circulation path that flows ink from the downstream side to the upstream side.

[0027] The on-off valve 73 is disposed downstream of the ink tank 71. The on-off valve 73 is configured to be able to open or close the ink supply path 72. Here, for example, "the on-off valve 73 opens or closes the ink supply path 72" includes a case where the on-off valve 73 completely opens or closes the flow path of the ink supply path 72 and a case where the on-off valve 73 partially opens the flow path of the ink supply path 72. When the on-off valve 73 is opened, the flow path of the ink supply path 72 is opened, and when the on-off valve 73 is closed, the flow path of the ink supply path 72 is closed. By the on-off valve 73 opening the flow path of the ink supply path 72, the ink stored in the ink tank 71 can be led to the ink supply path 72. 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 liquid feed pump 74 is disposed between the damper 76 and the ink tank 71 in the ink supply path 72. In this embodiment, it is disposed between the on-off valve 73 and the electromagnetic switching valve 75. The liquid feed pump 74 is a pump that feeds ink in a direction toward the ink head 40, i.e., downstream. When the on-off valve 73 is open, the liquid feed pump 74 can be driven to supply the ink contained in the ink tank 71 to the nozzles 41. The type of the liquid feed pump 74 is not particularly limited, but the liquid feed pump 74 is, for example, a diaphragm pump or a tube pump. The liquid feed pump 74 is electrically connected to a control device 90 (see FIG. 5) and is controlled by the control device 90.

[0029] The electromagnetic switching valve 75 is disposed between the liquid feed pump 74 and the damper 76 in the ink supply passage 72. FIG. 6 is a perspective view of the electromagnetic switching valve 75. The electromagnetic switching valve 75 is a valve that contains ink and is configured to be volume-variable. The electromagnetic switching valve 75 changes the volume of an ink containing section 751c (see FIG. 7) described later. The electromagnetic switching valve 75 switches the ink containing section 751c between a first state and a second state. Here, the first state refers to a state in which the volume of the ink containing section 751c described later is a first volume. The second state refers to a state in which the volume of the ink containing section 751c described later is a second volume that is larger than the first volume. FIG. 7 is a cross-sectional view of the electromagnetic switching valve 75 in the AA cross section shown in FIG. 6, and illustrates the electromagnetic switching valve 75 in the first state. FIG. 8 illustrates the electromagnetic switching valve 75 in the second state. The electromagnetic switching valve 75 is an example of an auxiliary container in the present invention. As shown in FIG. 4, in this embodiment, three electromagnetic switching valves 75 are provided in the ink supply passage 72. Here, the three electromagnetic switching valves 75 are also referred to as electromagnetic switching valves 75A, 75B, and 75C, respectively, in order from the upstream side of the ink supply passage 72. In this embodiment, the electromagnetic switching valves 75A, 75B, and 75C all have the same structure. In the following description, when a description is common to all of the electromagnetic switching valves 75A, 75B, and 75C, the term "electromagnetic switching valve 75" will be used as appropriate. Note that the number of electromagnetic switching valves 75 is not limited to three. The structure of the electromagnetic switching valve 75 will be described below.

[0030] As shown in Figures 7 and 8, the electromagnetic switching valve 75 includes a main body 750 and a solenoid 760. The main body 750 is a portion through which ink passes. The solenoid 760 is a portion that switches between a first state and a second state. Figure 9 is an enlarged view of the main body 750 in Figure 8.

[0031] As shown in FIG. 7, the main body 750 includes a main body 751, a valve valve body 752, a cover 753, a valve rod 754, a first spring holder 755 (see FIG. 9), a second spring holder 756 (see FIG. 9), a pressure adjusting member 757, a first spring 810 (see FIG. 9), and a second spring 820 (see FIG. 9).

[0032] As shown in FIG. 9, the main body 751 is formed with an inflow path 751a, an inlet 751b, an ink containing portion 751c, and an outflow path 751d.

[0033] The inflow path 751a is formed in the lower part of the main body 751 and is a flow path through which ink passes. The inflow path 751a is connected to the ink supply path 72 (see FIG. 4). Ink passing through the ink supply path 72 flows into the electromagnetic switching valve 75 from the inflow path 751a. The inflow path 751a includes a horizontal inflow path 751aa that extends horizontally and a vertical inflow path 751ab that extends vertically. The horizontal inflow path 751aa and the vertical inflow path 751ab are connected below the ink storage section 751c.

[0034] The inflow port 751b is connected to the bottom surface of the ink containing portion 751c. The inflow port 751b communicates with the ink containing portion 751c. The inflow port 751b is a portion through which the ink that has passed through the inflow channel 751a flows into the ink containing portion 751c.

[0035] The ink containing section 751c is a section that contains ink and is configured to be able to change its volume. The ink containing section 751c has a space 752a. The space 752a is a space surrounded by the ink containing section 751c and the valve valve body 752. Ink flows into the space 752a. In this embodiment, the valve valve body 752 elastically deforms, changing the shape of the space 752a and changing the volume of the ink containing section 751c. The volume of the ink containing section 751c in the first state shown in FIG. 7 is defined as a first volume V1. The volume of the ink containing section 751c in the second state shown in FIG. 8 is defined as a second volume V2. The second volume V2 is larger than the first volume V1. However, the first volume V1 is a value larger than 0. When the volume of the ink containing section 751c changes from V1 to V2, the volume of the entire ink supply path 72 (see FIG. 4) increases by V2-V1. Therefore, the pressure of the ink inside the ink supply passage 72 is reduced. That is, the pressure of the ink inside the damper 76, which will be described later, is reduced.

[0036] The outflow path 751d is formed in the lower part of the main body 751, and is a flow path through which the ink passes. The outflow path 751d is connected to the ink containing portion 751c. The outflow path 751d is a path through which the ink flows out from the ink containing portion 751c. The outflow path 751d is connected to the ink supply path 72 (see FIG. 4).

[0037] The valve valve body 752 forms the upper end of the space 752a. The valve valve body 752 changes the shape of the space 752a by elastic deformation. That is, the volume of the ink containing section 751c changes by the deformation of the valve valve body 752. The valve valve body is an example of an elastic body in the present invention. The valve valve body 752 is supported with its outer circumferential end sandwiched between the main body 751 and the cover 753. The valve valve body 752 is formed of a flexible material such as rubber. As shown in FIG. 7, the valve valve body 752 is pressed downward by the valve rod 754 in the first state. Therefore, the valve valve body 752 is deformed to have a downward convex shape with its outer circumferential end as a fixed end. However, the valve valve body 752 is disposed at a position that does not close the inlet 751b. That is, even in the first state, the inflow path 751a, the inlet 751b, the ink storage section 751c, and the outflow path 751d are in communication with each other in the electromagnetic switching valve 75. Therefore, the electromagnetic switching valve 75 communicates between the area of ​​the ink supply path 72 (see FIG. 4) upstream of the electromagnetic switching valve 75 and the area downstream of the electromagnetic switching valve 75.

[0038] The cover 753 is provided above the valve body 752. As shown in FIG. 9, the cover 753 holds the outer peripheral end of the valve body 752 together with the main body 751. The cover 753 is fixed to the main body 751 by a screw 840. The cover 753 has a cylindrical protrusion 753a formed in a hollow shape. Inside the protrusion 753a, a first spring holder 755, a second spring holder 756, a first spring 810, and a part of the valve rod 754 are arranged. In addition, a second spring 820 is attached so as to surround the protrusion 753a.

[0039] The valve rod 754 is a cylindrical member connected to the valve body 752 and elastically deforms the valve body 752 by moving up and down. The valve rod 754 is connected to the upper part of the valve body 752. The valve rod 754 has a head 754a located at the upper end and a body 754b extending in the vertical direction. The valve rod 754 is assembled so that the head 754a is disposed above the pressure regulating member 757 and a part of the body 754b is disposed inside the pressure regulating member 757. As shown in FIG. 9, when the solenoid switching valve 75 is in the second state, the upper end of the pressure regulating member 757 abuts against the lower end of the head 754a. Therefore, when the pressure regulating member 757 moves upward, the head 754a is pushed upward, and the valve rod 754 moves together with the pressure regulating member 757.

[0040] The first spring holder 755 and the second spring holder 756 are disposed inside the convex portion 753a of the cover 753. The first spring holder 755 is connected to the valve rod 754. The first spring holder 755 is a member having a convex shape through which the valve rod 754 is inserted. The second spring holder 756 is a member having a concave shape through which the valve rod 754 is inserted. The first spring holder 755 and the second spring holder 756 are disposed so as to face each other via the first spring 810. As a result, the elastic force of the first spring 810 is applied to the first spring holder 755 and the second spring holder 756. That is, the first spring holder 755 applies a force in a direction to push the valve rod 754 downward. The second spring holder 756 is pressed against the cover 753 by applying a force in a direction to push the cover 753.

[0041] The pressure regulating member 757 is placed on the upper end of the second spring 820. The pressure regulating member 757 is placed on the second spring 820 and assembled so as to be movable up and down by the expansion and contraction of the second spring 820. The pressure regulating member 757 is formed with a first insertion hole 757a and a second insertion hole 757b below the head 754a of the valve rod 754. The first insertion hole 757a and the second insertion hole 757b are holes through which the valve rod 754 is inserted. The first insertion hole 757a is a hole whose radial center position is aligned with the radial center position of the valve rod 754. The second insertion hole 757b is formed above the first insertion hole 757a. The radial center position of the second insertion hole 757b is horizontally shifted from the center position of the first insertion hole 757a (leftward in the drawing view of FIG. 9). The second insertion hole 757b overlaps with a portion of the first insertion hole 757a in a plan view. A shoulder 757c is formed in the pressure adjustment member 757 due to a misalignment between the center position of the first insertion hole 757a and the center position of the second insertion hole 757b. The shoulder 757c is located inside the outer diameter of the head 754a in the radial direction of the valve rod 754. Therefore, when the pressure adjustment member 757 is pushed upward by the elastic force of the second spring 820, the shoulder 757c comes into contact with the head 754a, and the valve rod 754 is also pushed upward.

[0042] First spring 810 is disposed so as to surround valve rod 754. First spring 810 is disposed so that both ends thereof contact first spring holder 755 and second spring holder 756. First spring 810 applies a downward elastic force to first spring holder 755.

[0043] Second spring 820 is disposed so as to surround valve rod 754 and protrusion 753a of cover 753. Second spring 820 is disposed with both ends in contact with cover 753 and pressure adjustment member 757. Second spring 820 applies an upward elastic force to pressure adjustment member 757. Within the operating range of solenoid switching valve 75, the elastic force of second spring 820 is always greater than the elastic force of first spring 810.

[0044] As shown in FIGS. 7 and 8, the solenoid 760 has a solenoid body 761 and a shaft core 762. The solenoid body 761 has a space 761a inside that is open downward. A solenoid coil is wound around the space 761a of the solenoid body 761. When the solenoid coil is energized, an upward attraction force is generated in the shaft core 762. The shaft core 762 is inserted into the space 761a of the solenoid body 761 and is movable up and down relative to the solenoid body 761. The shaft core 762 is capable of contacting the pressure adjustment member 757, and comes into contact with the pressure adjustment member 757 by moving downward. A flange 763 extending laterally is provided at the lower part of the shaft core 762.

[0045] In this embodiment, the solenoid 760 is provided with a third spring 830. The third spring 830 is disposed so as to surround the shaft core 762. The third spring 830 is interposed between the solenoid body 761 and the flange 763. The third spring 830 applies a downward elastic force to the shaft core 762. The third spring 830 applies an elastic force to the shaft core 762 in a direction away from the solenoid body 761. Within the operating range of the solenoid switching valve 75, the elastic force of the third spring 830 is equal to or greater than the elastic force of the second spring 820. Within the operating range of the solenoid switching valve 75, the elastic force of the third spring 830 is always smaller than the suction force of the solenoid 760.

[0046] In this embodiment, the vertical position of shaft core 762 relative to solenoid body 761 and the range of movement of shaft core 762 are changed by turning solenoid 760 ON or OFF. Note that turning solenoid 760 ON here refers to a state in which electricity is flowing, and turning solenoid 760 OFF refers to a state in which electricity is not flowing. The structure of solenoid switching valve 75 has been described above.

[0047] As shown in FIG. 4, 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 liquid feed 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.

[0048] 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 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).

[0049] 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.

[0050] In this embodiment, the control device 90 is communicatively connected to the liquid feed pump 74. The control device 90 drives the liquid feed pump 74. The control device 90 is also communicatively connected to the solenoid 760 of the electromagnetic switching valve 75. The control device 90 controls the ON / OFF of the solenoid 760.

[0051] In this embodiment, the control device 90 includes a pressurization control unit 91, a switching unit 92, a cleaning control unit 93, and a discharge pressure control unit 94. 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.

[0052] The pressure control unit 91 drives the liquid supply pump 74 to control the pressure inside the damper 76 to the pressure during pressure cleaning. The pressure during pressure cleaning is a pressure higher than the pressure inside the damper 76 when the ink head 40 ejects ink onto the recording medium 5. For example, the pressure during pressure cleaning is a pressure at which the meniscus formed in the nozzle 41 (see FIG. 2) bulges outward from the nozzle 41, or a pressure at which the meniscus breaks. The pressure inside the damper 76 is controlled based on the measurement value of the pressure sensor 77.

[0053] The switching unit 92 switches the electromagnetic switching valve 75 between a first state and a second state. That is, the switching unit 92 switches the solenoid 760 between ON and OFF. In this embodiment, the switching unit 92 is configured to be able to independently control the switching of the electromagnetic switching valves 75A, 75B, and 75C. The switching unit 92 is configured to set at least one of the electromagnetic switching valves 75A, 75B, and 75C to the first state and at least one to the second state when the pressurization control unit 91 controls the pressure inside the damper 76 to the pressure during pressurized cleaning.

[0054] The cleaning control unit 93 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 93. The cleaning control unit 93 performs each process, for example, in the order of the suction process, the wiping process, and the flushing process. However, the cleaning control unit 93 may perform any one or two of the above-mentioned processes. In addition, the order in which the cleaning control unit 93 performs each process is not particularly limited.

[0055] The discharge pressure control unit 94 controls the pressure inside the damper 76 to the pressure when the ink head 40 discharges ink onto the recording medium 5. The pressure at this time is referred to as the discharge pressure. The discharge pressure control unit 94 stops the liquid feed pump 74 and switches at least one of the electromagnetic switching valves 75 in the first state to the second state. When the electromagnetic switching valve 75 is switched from the first state to the second state, the volume of the ink storage section 751c of the electromagnetic switching valve 75 increases, and the pressure inside the damper 76 decreases. The number of electromagnetic switching valves 75 that the discharge pressure control unit 94 switches may be determined in advance.

[0056] Next, there will be described the switching operation of the electromagnetic switching valve 75. The electromagnetic switching valve 75 is switched by turning a solenoid 760 ON or OFF, whereby a shaft core 762 moves up and down.

[0057] FIG. 7 illustrates the solenoid switching valve 75 when the solenoid 760 is in the OFF state. At this time, the solenoid switching valve 75 is in the first state. When the solenoid 760 is OFF, no suction force is generated in the solenoid 760. Therefore, the shaft core 762 moves downward due to the elastic force of the third spring 830. At this time, the shaft core 762 comes into contact with the pressure adjustment member 757. The shaft core 762 moves the pressure adjustment member 757 downward until the elastic force of the third spring 830 and the elastic force of the second spring 820 are balanced. At this time, the shoulder 757c of the pressure adjustment member 757, which has been in contact with the head 754a of the valve rod 754, moves away from the head 754a. Therefore, the elastic force of the second spring 820 no longer acts on the valve rod 754. When the elastic force of the second spring 820 no longer acts on the valve rod 754, a downward elastic force is applied by the first spring 810 to the first spring holder 755 connected to the valve rod 754. Therefore, a downward elastic force is applied by the first spring 810 to the valve rod 754 via the first spring holder 755. That is, the valve rod 754 moves downward. At this time, the valve rod 754 deforms the valve valve body 752 so as to be convex downward, and the volume of the ink containing section 751c decreases. The volume of the ink containing section 751c at this time is the first volume V1.

[0058] When the electromagnetic switching valve 75 is in the first state, if the ink pressure inside the ink containing section 751c exceeds a predetermined pressure, the force with which the pressure inside the ink containing section 751c presses the valve valve body 752 exceeds the elastic force of the first spring 810, and the valve valve body 752 deforms upward. In other words, the valve valve body 752 deforms in the direction in which the volume of the ink containing section 751c increases.

[0059] FIG. 8 illustrates the solenoid switching valve 75 when the solenoid 760 is ON. At this time, the solenoid switching valve 75 is in the second state. When the solenoid 760 is ON, an upward attractive force is generated in the solenoid 760. The attractive force moves the shaft core 762 upward and collides with the inside of the solenoid body 761. At this time, the shaft core 762 separates from the pressure adjustment member 757. When the shaft core 762 separates from the pressure adjustment member 757, the elastic force of the third spring 830 no longer acts on the pressure adjustment member 757. At this time, the second spring 820 pushes the pressure adjustment member 757 upward. When the shoulder portion 757c of the pressure adjustment member 757 abuts against the head portion 754a of the valve rod 754, the valve rod 754 is pushed upward. Here, since the elastic force of the second spring 820 is greater than the elastic force of the first spring 810, the valve rod 754 is pushed upward. As the valve rod 754 is pushed upward, the valve valve body 752 connected to the valve rod 754 is deformed upward. Therefore, the volume of the ink containing section 751c increases. The volume of the ink containing section 751c at this time is the second volume V2.

[0060] Next, an operation for returning the pressure inside the damper 76 to the discharge pressure after performing the pressurized cleaning will be described. Fig. 10 is a flow chart explaining the procedure for performing the pressurized cleaning and then returning the pressure inside the damper 76 to the discharge pressure. Note that in the following flow, it is assumed that the on-off valve 73 (see Fig. 4) is open.

[0061] In step S101, the pressurization control unit 91 pressurizes the inside of the damper 76 by driving the liquid feed pump 74. As a result, the pressure inside the damper 76 becomes the pressure during pressurized cleaning. In step S102, the switching unit 92 switches the electromagnetic switching valve 75. For example, the switching unit 92 controls the energization state of each solenoid 760 so that the electromagnetic switching valve 75A is in the first state and the electromagnetic switching valves 75B and 75C are in the second state.

[0062] In step S103, the cleaning control unit 93 performs a suction process, a wiping process, and a flushing process to clean the ink head 40. That is, pressure cleaning is performed in step S103. Note that the cleaning of the ink head 40 is performed at the cleaning position P1.

[0063] In step S104, the ejection pressure control unit 94 reduces the pressure inside the damper 76 by switching the electromagnetic switching valve 75. In this embodiment, in step S103, the electromagnetic switching valve 75A, which was in the first state, is switched to the second state. By switching the electromagnetic switching valve 75A from the first state to the second state, the volume of the ink containing section 751c increases, and the pressure inside the damper 76 drops to the ejection pressure.

[0064] In step S105, the user decides whether or not to perform pressurized cleaning again. Whether or not to perform pressurized cleaning is selected, for example, by operating the operation panel 12. If pressurized cleaning is to be performed again, proceed to step S101. When starting the flow from step S101 again, the electromagnetic switching valves 75 that are set to the first state in step S102 are set to the first state for the electromagnetic switching valves 75 that were not switched to the first state in the previous flow. For example, when the flow from step S101 to step S105 is performed three times, the electromagnetic switching valve 75A is set to the first state in the first flow, the electromagnetic switching valve 75B is set to the first state in the second flow, and the electromagnetic switching valve 75C is set to the first state in the third flow. Note that, for example, printing by the inkjet printer 100 may be performed between step S104 and step S105. If pressurized cleaning is not to be performed in step S105, the flow is terminated.

[0065] As described above, according to the printer 100 of this embodiment, by driving the liquid feed pump 74, the ink stored in the ink tank 71 is sent to the nozzle 41 of the ink head 40 through the ink supply path 72 and the damper 76. The pressure inside the damper 76 becomes a pressure according to the driving of the liquid feed pump 74. By increasing the internal pressure of the damper 76, the pressurized cleaning can be performed. The pressure during the execution of the pressurized cleaning is higher than the ejection pressure. After the pressurized cleaning is performed, the electromagnetic switching valve 75 is switched to increase the volume of the ink storage section 751c, thereby reducing the pressure inside the damper 76. Therefore, the pressure inside the damper 76 can be reduced without ejecting ink from the ink head 40. According to this embodiment, it is not necessary to eject ink in order to return the internal pressure of the damper 76 to the ejection pressure. It is not necessary to eject ink before starting printing after the pressurized cleaning is performed. Therefore, it is possible to reduce wasteful consumption of ink.

[0066] According to the above-described embodiment, the electromagnetic switching valve 75 can be switched between a first state in which the volume of the ink containing section 751c is a first volume V1 and a second state in which the volume of the ink containing section 751c is a second volume V2. The second volume V2 is larger than the first volume V1. Even in the first state, the electromagnetic switching valve 75 has the inflow path 751a, the inlet 751b, the ink containing section 751c, and the outlet path 751d in communication. The inflow path 751a and the outlet path 751d are connected to the ink supply path 72. That is, the upstream side and downstream side of the electromagnetic switching valve 75 in the ink supply path 72 are in communication. Here, if the communication between the inflow path 751a, the inlet 751b, the ink containing section 751c, and the outlet path 751d is interrupted, the ink in the ink containing section 751c will not flow, and therefore the ink may settle. Sedimentation of ink leads to quality degradation such as uneven color in the printed portion. In this embodiment, ink can flow from the ink containing section 751c even in the first state in which the volume of the ink containing section 751c is at its smallest, so ink sedimentation is relatively unlikely to occur. Therefore, deterioration in the quality of the printed matter can be suppressed.

[0067] According to the embodiment described above, the inlet 751b, which is the portion through which the ink enters the ink containing portion 751c, is connected to the bottom surface of the ink containing portion 751c. Therefore, the ink flowing into the ink containing portion 751c flows from the bottom toward the top of the ink containing portion 751c. This causes the ink near the bottom of the ink containing portion 751c to flow upward. Therefore, sedimentation of the ink inside the ink containing portion 751c is relatively unlikely to occur. This makes it possible to suppress deterioration in the quality of the printed matter.

[0068] According to the above-mentioned embodiment, the electromagnetic switching valve 75 is provided in a plurality of units in the ink supply passage 72. Here, when the volume of the ink storage section 751c is relatively large, when the ink passes through the main body 750 of the electromagnetic switching valve 75, the amount of ink flowing among the ink inside the ink storage section 751c is small compared to the total ink inside the ink storage section 751c. At this time, the ink is relatively likely to settle inside the ink storage section 751c. On the other hand, the degree to which the inside of the damper 76 is depressurized when switching from the first state to the second state is determined by the volume of the ink storage section 751c. As in this embodiment, by providing a plurality of electromagnetic switching valves 75 in the ink supply passage 72, the volume of the ink storage section 751c of each electromagnetic switching valve 75 can be made smaller than when only one electromagnetic switching valve 75 is provided. When the volume of the ink storage section 751c is small, the ink is relatively likely to flow inside the ink storage section 751c. As a result, sedimentation of the ink is relatively unlikely to occur, and therefore deterioration in the quality of the printed matter can be suppressed while still allowing the pressure inside the damper 76 to be the ejection pressure.

[0069] According to the embodiment described above, the auxiliary container is an electromagnetic switching valve 75 that can be switched between a first state and a second state. The electromagnetic switching valve 75 can be switched between the first state and the second state by switching the energization of the solenoid 760. Therefore, it is relatively easy to switch between the first state and the second state.

[0070] According to the embodiment described above, when the pressure control unit 91 of the control device 90 sets the pressure inside the damper 76 to the pressure during pressurized cleaning, the switching unit 92 controls the electromagnetic switching valve 75A to the first state and the electromagnetic switching valves 75B and 75C to the second state. This allows the electromagnetic switching valve 75 that is set to the first pressure when the pressure during pressurized cleaning is reached to be rotated. Therefore, even when multiple electromagnetic switching valves 75 are provided, ink sedimentation is relatively unlikely to occur in all of the electromagnetic switching valves 75. This makes it possible to prevent deterioration in the quality of printed matter.

[0071] According to the above-described embodiment, when the electromagnetic switching valve 75 is in the first state, if the pressure of the ink inside the ink containing section 751c exceeds a predetermined pressure, the valve valve body 752 deforms upward. That is, the valve valve body 752 deforms in the direction in which the volume of the ink containing section 751c increases. Therefore, the pressure of the ink inside the ink containing section 751c is kept from exceeding the predetermined pressure. By setting the multiple electromagnetic switching valves 75 to the first state, the value of the predetermined pressure becomes higher. That is, the pressure inside the damper 76 can be determined by the number of the multiple electromagnetic switching valves 75 that are set to the first state. This makes it possible to adjust the pressure inside the damper 76 by the electromagnetic switching valve 75.

[0072] 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 suction processing, wiping processing, and flushing processing. Therefore, more processing can be performed in pressurized cleaning, improving the cleaning effect.

[0073] 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]

[0074] 40 Ink Head 41 Nozzle 42 Nozzle surface 71 Ink tank 72 Ink supply path 74 Liquid delivery pump 75 Solenoid switching valve (auxiliary container) 751c Ink storage unit 76 Damper 100 Printer (inkjet printer)

Claims

1. 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 liquid feed pump disposed in the ink supply path between the damper and the ink tank, the liquid feed pump feeding the ink in a direction toward the ink head; an auxiliary container disposed in the ink supply path between the liquid feed pump and the damper; The auxiliary container is an inkjet printer having an ink storage section that stores the ink and is configured to be volume-variable.

2. the auxiliary container is configured to be changeable between a first state in which the ink containing section has a first volume and a second state in which the ink containing section has a second volume larger than the first volume; The inkjet printer according to claim 1 , wherein the auxiliary container, when in the first state, communicates an area of ​​the ink supply path upstream of the auxiliary container with an area downstream of the auxiliary container.

3. the auxiliary container is in communication with the ink storage section and has an inlet through which the ink flows; The inkjet printer according to claim 1 , wherein the inlet is connected to a lower surface of the ink containing portion.

4. The inkjet printer according to claim 1 , wherein a plurality of the auxiliary containers are provided in the ink supply path.

5. 3. The ink jet printer according to claim 2, wherein the auxiliary container is an electromagnetic switching valve that is switchable between the first state and the second state.

6. a control device for controlling the ink head, the liquid feed pump, and the electromagnetic switching valve; a plurality of the electromagnetic switching valves are provided in the ink supply passage; The control device includes: a pressure control unit that drives the liquid feed pump to make the pressure inside the damper higher than the pressure when the ink head ejects the ink onto a printed material; a switching unit that switches the electromagnetic switching valve between the first state and the second state, 6. The inkjet printer according to claim 5, wherein the switching unit switches at least one of the plurality of electromagnetic switching valves to the first state and switches at least another of the plurality of electromagnetic switching valves to the second state when the pressure inside the damper is controlled by the pressurization control unit.

7. the plurality of electromagnetic switching valves are disposed inside the ink containing section and each include an elastic body that changes a volume of the ink containing section between the first volume and the second volume; 7. The ink jet printer according to claim 6, wherein the elastic body elastically deforms in a direction increasing a volume of the ink containing section when a pressure applied to the ink containing section reaches or exceeds a predetermined pressure while the electromagnetic switching valve is in the first state.

8. 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; 2. The inkjet printer according to claim 1, 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.

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