Inkjet recording device

Abstract

In an inkjet recording device (1), an intermediate flow passage (53) is connected to a downstream section of a first flow passage (89) in the ink flow direction, and is in communication with a recording head (52) and a second flow passage (90). A communicating flow passage (54) includes a first branch flow passage (54A) that supplies ink from the intermediate flow passage (53) to the recording head (52), a second branch flow passage (54B) that causes the ink to circulate from the recording head (52) to the second flow passage (90), and a third branch flow passage (54C) that causes the ink to flow from the intermediate flow passage (53) to the second flow passage (90). Opening / closing valves (96), (55A), (55B), (55C) are respectively provided to a third flow passage (91) and the first branch flow passage (54A), the second branch flow passage (54B), and the third branch flow passage (54C) that make up the communicating flow passage (54).

Description

[Technical Field]

[0001] The present invention relates to an inkjet recording apparatus. [Background technology]

[0002] An inkjet recording device includes a recording head that ejects ink onto a recording medium such as paper to record an image. For example, when an inkjet recording device is shipped from a factory, the ink supply side may be emptied to prevent leakage, and the recording head side may be filled with transport liquid to ensure the quality of the flow path. For this reason, some inkjet recording devices have the ink supply side and the recording head side detachable by a coupling or the like.

[0003] The conventional inkjet recording device disclosed in Patent Document 1 is provided with detachable couplings in both a supply path through which ink passes when it is supplied from a supply unit to a recording head, and a circulation path through which ink returns from the recording head to the supply unit. The upstream portions of the supply path connected to the two couplings are connected to the downstream portion of the circulation path by bypass paths that can be connected and disconnected.

[0004] This allows ink to be circulated and filled into the supply unit via the bypass path without passing through the print head when the inkjet printing apparatus is delivered. After that, the two couplings are connected to communicate the supply path and the circulation path, and the preservative liquid in the print head is replaced with ink, thereby preventing air bubbles from being trapped in the ink in the print head. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Publication No. 2019-171648 Summary of the Invention [Problem to be solved by the invention]

[0006] In the conventional inkjet recording device described above, a clamp that opens and closes the ink flow path is provided in the bypass path. When substituting a different ink, the amount of ink in the sub-ink tank where the ink is stored is gradually reduced to perform the substitution process. However, because the ink in the bypass path cannot be substituted, the clamp must be opened and closed manually multiple times. Furthermore, to reduce the amount of ink consumed during substitution, it is necessary to drain the ink from the supply unit. To prevent the ink meniscus in the recording head from collapsing, the coupling connecting the supply unit and the recording head must be removed and the ink must be drained separately using a suction tool or the like. Thus, substituting a different ink requires a lot of effort, increases ink consumption, and increases the time required.

[0007] The present invention has been made in consideration of the above points, and aims to provide an inkjet recording device that simplifies the process of replacing ink with a different ink, and that can reduce ink consumption and the time required. [Means for solving the problem]

[0008] In order to solve the above problems, the inkjet recording apparatus of the present invention includes a recording head, an ink container, a first sub-tank, a second sub-tank, a circulation pump, a pressurizing unit, a decompression unit, a syringe, a first flow path, a second flow path, a third flow path, an intermediate flow path, and a communication flow path. One or more recording heads are provided, each having a plurality of nozzles that eject ink onto a recording medium. The ink container stores the ink to be supplied to the recording head. The first sub-tank temporarily stores the ink supplied from the ink container. The second sub-tank temporarily stores the ink supplied from the first sub-tank. The circulation pump moves the ink from the first sub-tank to the second sub-tank. The pressurizing unit pressurizes the second sub-tank and supplies the ink from the second sub-tank to the recording head. The decompression unit decompresses the first sub-tank and circulates the ink from the recording head to the first sub-tank. The syringe allows the ink to flow in from the second sub-tank and out toward the print head, and is capable of applying a maintenance pressure to the ink that is higher than the print pressure applied by the pressurizing unit. The first flow path distributes the ink from the first sub-tank to the print head via the circulation pump, the second sub-tank, and the syringe. The second flow path circulates the ink from the print head to the first sub-tank. The third flow path connects the upstream side of the print head in the ink flow direction of the first flow path to the downstream side of the print head in the ink flow direction of the second flow path. The intermediate flow path is connected to a downstream portion of the first flow path in the ink flow direction and communicates with the print head and the second flow path. The communication flow path includes a first branch flow path that supplies the ink from the intermediate flow path to the print head, a second branch flow path that circulates the ink from the print head to the second flow path, and a third branch flow path that distributes the ink from the intermediate flow path to the second flow path. The third flow path and the first branch flow path, the second branch flow path, and the third branch flow path that configure the communication flow path each include an on-off valve. [Effects of the Invention]

[0009] According to the configuration of the present invention, by opening and closing the on-off valves provided in each of the third flow path, the first branch flow path, the second branch flow path, and the third branch flow path in an appropriate sequence, the operation becomes easier when replacing with a different ink, and it becomes possible to reduce the amount of ink consumed and the time required. [Brief explanation of the drawings]

[0010] [Figure 1] 1 is a schematic cross-sectional front view of an inkjet recording apparatus according to an embodiment of the present invention. [Figure 2] FIG. 2 is a plan view of the periphery of a recording unit of the inkjet recording apparatus of FIG. [Figure 3] FIG. 2 is a block diagram of the inkjet recording apparatus of FIG. [Figure 4] FIG. 2 is an explanatory diagram of the periphery of an ink supply unit of the inkjet recording apparatus of FIG. [Figure 5] FIG. 5 is a cross-sectional view of a syringe of the ink supply unit of FIG. 4. [Figure 6] 5 is an explanatory diagram of an on-off valve of the ink supply unit of FIG. 4. [Figure 7] 5 is an enlarged explanatory view of the periphery of the intermediate flow path and the communication flow path in FIG. 4. DETAILED DESCRIPTION OF THE INVENTION

[0011] Hereinafter, an embodiment of the present invention will be described with reference to the drawings, but the present invention is not limited to the following.

[0012] FIG. 1 is a schematic cross-sectional front view of an inkjet recording apparatus 1 according to an embodiment. FIG. 2 is a plan view of the recording unit 5 and its surroundings of the inkjet recording apparatus 1 of FIG. 1. FIG. 3 is a block diagram of the inkjet recording apparatus 1 of FIG. 1. The inkjet recording apparatus 1 is, for example, an inkjet recording printer. As shown in FIGS. 1, 2, and 3, the inkjet recording apparatus 1 includes a device main body 2, a paper supply unit 3, a paper transport unit 4, a recording unit 5, a drying unit 6, and a control unit 7.

[0013] The paper supply unit 3 is disposed, for example, at the bottom of the device main body 2. The paper supply unit 3 stores a plurality of sheets of paper (recording media) S, and separates and feeds out the sheets S one by one during recording.

[0014] The paper transport unit 4 is disposed downstream of the paper supply unit 3 in the paper transport direction, and transports the paper S sent out from the paper supply unit 3. The paper transport unit 4 transports the paper S to the recording unit 5 and the drying unit 6, and then discharges the paper S after recording and drying to the paper discharge unit 21. The paper transport unit 4 has, for example, a reversing transport unit 4r. When double-sided recording is performed, the paper transport unit 4 distributes the paper S after recording and drying on the first side to the reversing transport unit 4r, and then switches the transport direction to reverse the paper S and transports it again to the recording unit 5 and the drying unit 6.

[0015] The paper transport unit 4 includes a first belt transport unit 41 and a second belt transport unit 42. The first belt transport unit 41 has a first transport belt 411 formed in an endless shape. The second belt transport unit 42 has a second transport belt 421 formed in an endless shape. The first belt transport unit 41 and the second belt transport unit 42 adsorb and hold the paper S on the upper outer surfaces (upper surfaces) of the first transport belt 411 and the second transport belt 421, respectively, and transport the paper S. The first belt transport unit 41 is disposed below the recording unit 5 and transports the paper S. The second belt transport unit 42 is located downstream of the first belt transport unit 41 in the paper transport direction, and is disposed in the drying unit 6 and transports the paper S.

[0016] The recording unit 5 is located downstream of the paper supply unit 3 in the paper conveying direction, and is arranged opposite the first belt conveying unit 41. The recording unit 5 faces the paper S that is conveyed while being attracted to and held on the upper surface of the first conveying belt 411, and is arranged above the first conveying belt 411 with a predetermined gap therebetween. In other words, the recording unit 5 faces the paper S that is conveyed by the paper conveying unit 4.

[0017] 2, the recording unit 5 holds head units 51B, 51C, 51M, and 51Y corresponding to four colors: black, cyan, magenta, and yellow. The head units 51B, 51C, 51M, and 51Y are arranged side by side along the paper transport direction Dc so that their longitudinal directions are parallel to the paper width direction Dw, which is perpendicular to the paper transport direction Dc. Note that the four head units 51B, 51C, 51M, and 51Y have the same basic configuration, so in the following explanation, the identification symbols "B," "C," "M," and "Y" representing each color may be omitted unless there is a particular need to specify them.

[0018] Each head unit 51 for each color has a line-type inkjet recording head 52. In each head unit 51 for each color, a plurality of recording heads 52 (for example, three (52a, 52b, 52c)) are arranged in a staggered pattern along the paper width direction Dw.

[0019] The recording head 52 has a plurality of ink ejection nozzles 521 at its bottom. The plurality of ink ejection nozzles 521 are arranged in a row along the paper width direction Dw, and can eject ink over the entire recording area on the paper S. In other words, the recording head 52 has a plurality of ink ejection nozzles 521 that eject ink onto the paper S. The recording unit 5 sequentially ejects ink from the recording heads 52 of the four color head units 51B, 51C, 51M, and 51Y toward the paper S transported by the first transport belt 411, and records a full-color image or a monochrome image on the paper S.

[0020] The drying unit 6 is disposed downstream of the recording unit 5 in the paper transport direction, and is provided with a second belt transport unit 42. The paper S on which an ink image has been recorded in the recording unit 5 is adsorbed and held by the second transport belt 421 in the drying unit 6, and the ink is dried while being transported.

[0021] The control unit 7 includes a CPU, a memory unit, and other electronic circuits and electronic components (none of which are shown). The CPU controls the operation of each component provided in the inkjet recording device 1 based on control programs and data stored in the memory unit to perform processing related to the functions of the inkjet recording device 1. The paper supply unit 3, paper transport unit 4, recording unit 5, and drying unit 6 each receive individual commands from the control unit 7 and work together to record on the paper S. The memory unit is configured by combining a non-volatile storage device such as a program ROM (Read Only Memory) or a data ROM with a volatile storage device such as a RAM (Random Access Memory).

[0022] Next, the configuration of the ink supply unit 8 of the inkjet recording apparatus 1 will be described with reference to Figs. 4 to 6. Fig. 4 is an explanatory diagram of the periphery of the ink supply unit 8 of the inkjet recording apparatus 1 of Fig. 1. Fig. 5 is a cross-sectional view of a syringe 88 of the ink supply unit 8 of Fig. 4. Fig. 6 is an explanatory diagram of an on-off valve of the ink supply unit 8 of Fig. 4. Fig. 7 is an enlarged explanatory diagram of the periphery of the intermediate flow path 53 and the communicating flow path 54 of Fig. 4.

[0023] The inkjet recording device 1 includes an ink supply unit 8. An ink supply unit 8 is provided for each of the four color head units 51. In the following description, the identification symbols representing each color will be omitted. The ink supply unit 8 and the head unit 51 are connected by a detachable coupling 11. A valve member (not shown) is built into the coupling 11, which opens the ink flow path in the connected state and closes the ink flow path in the separated state.

[0024] The ink supply unit 8 includes an ink container 81, a container pump 82, a first sub-tank 83, a circulation pump 84, a second sub-tank 85, a pressurizing unit 86, a depressurizing unit 87, a syringe 88, a first flow path 89, a second flow path 90, and a third flow path 91. The ink supply unit 8 also includes a fourth flow path 92, a first on-off valve 93, a second on-off valve 94, and a third on-off valve 95. The recording unit 5 also includes an intermediate flow path 53 and a communicating flow path 54.

[0025] The ink container 81 is detachably provided to the apparatus main body 2. The ink container 81 contains ink to be supplied to the recording head 52.

[0026] The container pump 82 is disposed downstream in the ink flow direction of the ink container 81. The container pump 82 sucks ink from the ink container 81 and discharges it toward the first sub-tank 83. The operation of the container pump 82 is controlled by the control unit 7.

[0027] The first sub-tank 83 is disposed downstream of the container pump 82 in the ink flow direction. The first sub-tank 83 temporarily stores ink supplied from the ink container 81. An ink amount sensor (not shown) is provided in the first sub-tank 83. The ink amount sensor includes, for example, an optical type, a capacitance type, an electrode type, a differential pressure type, or a float type sensor, and detects the amount of ink in the first sub-tank 83.

[0028] The control unit 7 receives a detection signal from the ink amount sensor of the first subtank 83. When the amount of ink in the first subtank 83 detected by the ink amount sensor falls below a predetermined value, the control unit 7 controls the container pump 82 to supply ink from the ink container 81 to the first subtank 83. The amount of ink supplied from the ink container 81 to the first subtank 83 is controlled, for example, by the operating time of the container pump 82. If the amount of ink in the first subtank 83 detected by the ink amount sensor does not rise above a predetermined value even after a certain period of operating time of the container pump 82 has elapsed, the control unit 7 determines that the ink container 81 is empty.

[0029] The circulation pump 84 is disposed downstream of the first sub-tank 83 in the ink flow direction. The circulation pump 84 moves ink from the first sub-tank 83 to the second sub-tank 85. The circulation pump 84 can be selected from liquid pumps such as a tube pump or a diaphragm pump. The operation of the circulation pump 84 is controlled by the control unit 7.

[0030] The second sub-tank 85 is disposed downstream in the ink flow direction from the circulation pump 84. The second sub-tank 85 temporarily stores ink supplied from the first sub-tank 83. Like the first sub-tank 83, the second sub-tank 85 is provided with an ink amount sensor (not shown) that detects the amount of ink in the second sub-tank 85.

[0031] The control unit 7 receives a detection signal from the ink amount sensor of the second subtank 85. When the amount of ink in the second subtank 85 detected by the ink amount sensor falls below a predetermined value, the control unit 7 controls the circulation pump 84 to move ink from the first subtank 83 to the second subtank 85. The amount of ink moved from the first subtank 83 to the second subtank 85 is controlled by, for example, the driving time of the circulation pump 84.

[0032] The pressurizing unit 86 is provided next to the second sub-tank 85. The pressurizing unit 86 applies pressure to the inside of the second sub-tank 85 and supplies ink from the second sub-tank 85 to the recording head 52. The operation of the pressurizing unit 86 is controlled by the control unit 7.

[0033] The pressurizing unit 86 includes a pressurizing chamber 861, a pressurizing pump 862, a pressurizing sensor 863, and a pressurizing chamber opening / closing mechanism 864. The pressurizing chamber 861 has a predetermined volume and is connected to the second sub-tank 85. The pressurizing pump 862 pressurizes the pressurizing chamber 861 by introducing air into the pressurizing chamber 861. The pressurizing sensor 863 detects the pressure inside the pressurizing chamber 861. The pressurizing chamber opening / closing mechanism 864 opens and closes the air communication path between the pressurizing chamber 861 and the atmosphere.

[0034] The control unit 7 analogically controls the operation of the pressure pump 862 and the pressure chamber opening / closing mechanism 864 in real time based on the detection signal of the pressure sensor 863. With this configuration, the inside of the second sub-tank 85 can be appropriately pressurized, and ink can be efficiently supplied from the second sub-tank 85 to the recording head 52.

[0035] The pressure reducing unit 87 is provided next to the first sub-tank 83. The pressure reducing unit 87 reduces the pressure inside the first sub-tank 83 and circulates ink from the recording head 52 to the first sub-tank 83. The operation of the pressure reducing unit 87 is controlled by the control unit 7.

[0036] The decompression section 87 includes a decompression chamber 871, a decompression pump 872, a decompression sensor 873, and a decompression chamber opening / closing mechanism 874. The decompression chamber 871 has a predetermined volume and is connected to the first sub-tank 83. The decompression pump 872 reduces the pressure by causing air to flow out from the decompression chamber 871. The decompression sensor 873 detects the pressure inside the decompression chamber 871. The decompression chamber opening / closing mechanism 874 opens and closes the air communication path between the decompression chamber 871 and the atmosphere.

[0037] The control unit 7 analogically controls the operation of the decompression pump 872 and the decompression chamber opening / closing mechanism 874 in real time based on the detection signal of the decompression sensor 873. With this configuration, the pressure inside the first sub-tank 83 can be suitably reduced, and ink can be efficiently circulated from the recording head 52 to the first sub-tank 83.

[0038] The pressurizing unit 86 and the depressurizing unit 87 are not limited to the above configurations. For example, a regulator may be used for the pressurizing unit 86 and the depressurizing unit 87, or a negative pressure generator and a pressure pump may be used.

[0039] Syringe 88 is disposed downstream in the ink flow direction of second sub-tank 85 and upstream in the ink flow direction of recording head 52. Ink flows into syringe 88 from second sub-tank 85 and flows out toward recording head 52. As shown in FIG. 5 , syringe 88 has a cylindrical portion 881 and a plunger 882.

[0040] The tubular portion 881 has a cylindrical shape and is disposed so that its axis extends in the vertical direction. The upper end of the tubular portion 881 is open. The lower end of the tubular portion 881 is closed, and a first conduit 891 extending from the second sub-tank 85 side of a first flow path 89 (described later) and a second conduit 892 extending toward the recording head 52 are connected to the lower end. The first conduit 891 and the second conduit 892 are in communication with the interior of the tubular portion 881.

[0041] The plunger 882 is inserted into the interior of the tube portion 881 from the upper end opening of the tube portion 881. The plunger 882 has a shaft portion 882a and a gasket portion 882b. The shaft portion 882a is formed so that its axis extends in the vertical direction. The gasket portion 882b is disposed at the lower end of the shaft portion 882a. The gasket portion 882b has a cylindrical shape that extends along the inner circumferential surface of the tube portion 881, and its outer circumferential surface is in close contact with the inner circumferential surface of the tube portion 881. This prevents ink in the tube portion 881 from leaking above the gasket portion 882b.

[0042] A fifth conduit 921 of the fourth flow path 92, which will be described later, is inserted into the radial center of the plunger 882. The fifth conduit 921 is in communication with the inside of the cylindrical portion 881. Air that remains inside the cylindrical portion 881, i.e., above the ink in the syringe 88 and below the gasket portion 882b, is discharged upward via the fifth conduit 921. The fourth flow path 92 extends to the second sub-tank 85.

[0043] The fourth flow path 92 extends from the syringe 88 to the second sub-tank 85. The fourth flow path 92 is an air flow path that discharges the air in the syringe 88 to the second sub-tank 85. The third on-off valve 95 is disposed on a fifth conduit 921 of the fourth flow path 92. The third on-off valve 95 opens and closes the fourth flow path 92. The third on-off valve 95 is configured, for example, by a solenoid valve, and its opening and closing is controlled by the control unit 7. The control unit 7 opens the third on-off valve 95 when the air in the syringe 88 is discharged.

[0044] A rack 882c is formed on the side of the shaft 882a. The rack 882c has a plurality of teeth arranged in parallel in the vertical direction, and a syringe drive gear 883 meshes with the rack 882c. The syringe drive gear 883 is connected to a syringe motor 884 (see FIG. 3) and receives power from the syringe motor 884 to rotate in both forward and reverse directions. The rotation of the syringe drive gear 883 in both forward and reverse directions allows the plunger 882 to reciprocate in the vertical direction. The operation of the syringe motor 884 is controlled by the control unit 7.

[0045] When an image is recorded on the paper S, a recording pressure is applied to the ink by the pressurizing unit 86. In contrast, for example, during maintenance, the control unit 7 can apply a maintenance pressure higher than the recording pressure to the ink by causing the syringe motor 884 to move the plunger 882 downward at high speed and pushing out the ink from the syringe 88. In other words, the syringe 88 can apply a maintenance pressure higher than the recording pressure applied to the ink by the pressurizing unit 86.

[0046] The first flow path 89 is an ink flow path through which ink flows from the first sub-tank 83 via the circulation pump 84, the second sub-tank 85, and the syringe 88 to the recording head 52. The first flow path 89 includes a first conduit 891 extending from the second sub-tank 85 to the syringe 88, a second conduit 892 extending from the syringe 88 to the recording head 52, and a third conduit 893 extending from the first sub-tank 83 to the second sub-tank 85. A check valve CV1 is disposed on the third conduit 893. The check valve CV1 prevents ink from flowing backward from downstream to upstream in the ink flow direction of the first flow path 89.

[0047] The first on-off valve 93 is disposed on a first conduit 891 of the first flow path 89, upstream of the syringe 88 in the ink flow direction. The first conduit 891 is a tube made of, for example, rubber, and can be deformed by bending or flexing. As shown in FIG. 6, the first on-off valve 93 has an on-off cam 93a and an on-off motor (not shown).

[0048] The opening / closing cam 93a is adjacent to the first conduit 891. The opening / closing cam 93a is formed in a wedge shape when viewed in the axial direction of the first conduit 891. The opening / closing cam 93a is supported so as to be rotatable about a rotation axis that is parallel to the axis of the first conduit 891. The opening / closing cam 93a is rotated and oscillated by an opening / closing motor, and the tip side of the wedge shape comes into contact with and separates from the first conduit 891.

[0049] When the first on-off valve 93 is opened, the control unit 7 controls the on-off motor to rotate the on-off cam 93a, and sets the on-off cam 93a to an angle that does not contact the first conduit 891 or deform the first conduit 891. This allows ink to flow through the first conduit 891 at the first on-off valve 93. When the first on-off valve 93 is closed, the control unit 7 controls the on-off motor to rotate the on-off cam 93a, and sets the on-off cam 93a to an angle that contacts the first conduit 891 and compresses the first conduit 891. This prevents ink from flowing through the first conduit 891 at the first on-off valve 93. The first on-off valve 93 opens and closes the first flow path 89 between the first subtank 83 and the syringe 88.

[0050] The second on-off valve 94 is disposed on the second conduit 892 of the first flow path 89. The configuration and operation of the second on-off valve 94 are similar to those of the first on-off valve 93 described above, and therefore a description thereof will be omitted here. The opening and closing of the second on-off valve 94 is controlled by the control unit 7. The second on-off valve 94 opens and closes the first flow path 89 between the syringe 88 and the recording head 52.

[0051] The second flow path 90 is an ink flow path through which ink circulates from the recording head 52 to the first sub-tank 83. The second flow path 90 includes a fourth conduit 901 that extends from the recording head 52 to the first sub-tank 83.

[0052] The third flow path 91 connects the upstream side of the recording head 52 in the ink flow direction of the first flow path 89 to the downstream side of the recording head 52 in the ink flow direction of the second flow path 90. More specifically, the third flow path 91 connects the second conduit 892 of the first flow path 89 to the fourth conduit 901 of the second flow path 90 in the vicinity of the coupling 11 within the ink supply unit 8.

[0053] In this embodiment, the intermediate flow path 53 is disposed, for example, above the recording head 52. The intermediate flow path 53 is connected to a downstream portion in the ink flow direction of the first flow path 89. The intermediate flow path 53 communicates with the recording head 52 and the second flow path 90.

[0054] The communication flow path 54 includes a first branch flow path 54A, a second branch flow path 54B, and a third branch flow path 54C. One end of the first branch flow path 54A in the ink flow direction is connected to the intermediate flow path 53, and the other end is connected to the recording head 52, so that the first branch flow path 54A supplies ink from the intermediate flow path 53 to the recording head 52. One end of the second branch flow path 54B in the ink flow direction is connected to the recording head 52, and the other end is connected to the second flow path 90, so that the ink circulates from the recording head 52 to the second flow path 90. One end of the third branch flow path 54C in the ink flow direction is connected to the intermediate flow path 53, and the other end is connected to the second flow path 90, so that the ink circulates from the intermediate flow path 53 to the second flow path 90.

[0055] The third flow path 91 is provided with a fourth on-off valve 96. The fourth on-off valve 96 opens and closes the flow of ink through the third flow path 91. The fourth on-off valve 96 is formed of, for example, a solenoid valve, and its opening and closing is controlled by the control unit 7.

[0056] Furthermore, each of the first branch flow path 54A, the second branch flow path 54B, and the third branch flow path 54C that make up the communication flow path 54 is provided with a branch on-off valve 55. More specifically, the branch on-off valve 55 includes branch on-off valves 55A, 55B, and 55C. The branch on-off valves 55A, 55B, and 55C open and close the flow of ink in the first branch flow path 54A, the second branch flow path 54B, and the third branch flow path 54C, respectively. The branch on-off valves 55A, 55B, and 55C are formed of, for example, solenoid valves, and their opening and closing is controlled by the control unit 7.

[0057] For example, when recording on paper S, the fourth on-off valve 96 and the branch on-off valve 55C of the third branch flow path 54C are closed. Also, when recording on paper S, the branch on-off valve 55A of the first branch flow path 54A and the branch on-off valve 55B of the second branch flow path 54B are opened.

[0058] Furthermore, when replacing with a different ink, the fourth on-off valve 96 and the branch on-off valves 55A, 55B, and 55C are switched between open and closed states depending on which region of the ink flow path the ink is being replaced in. For example, when replacing the ink in the third flow path 91, the fourth on-off valve 96 and the branch on-off valve 55C of the third branch flow path 54C are opened, and the branch on-off valve 55A of the first branch flow path 54A and the branch on-off valve 55B of the second branch flow path 54B are closed. When replacing the ink in the recording head 52, the fourth on-off valve 96, the branch on-off valve 55B of the second branch flow path 54B, and the branch on-off valve 55C of the third branch flow path 54C are closed, and the branch on-off valve 55A of the first branch flow path 54A is opened.

[0059] According to the above configuration, when replacing with a different ink, the ink flow can be switched appropriately by the fourth on-off valve 96 and the branch on-off valves 55A, 55B, and 55C. This simplifies the ink replacement work, and makes it possible to reduce the amount of ink consumed during replacement and shorten the required time.

[0060] The inkjet recording device 1 configured as described above includes a first sub-tank 83, a circulation pump 84, a second sub-tank 85, a pressurizing unit 86, and a decompression unit 87, and circulates ink using the two sub-tanks. In the inkjet recording device 1 with this ink circulation system, the ink replacement work is simplified, and it is possible to reduce the amount of ink consumed during replacement and shorten the time required.

[0061] The inkjet recording apparatus 1 also includes a waste liquid flow path 97, a waste liquid tank 12, and a waste liquid pump 13.

[0062] The waste liquid flow path 97 is connected to one of the first sub-tank 83 and the second sub-tank 85. In this embodiment, the waste liquid flow path 97 is connected to the first sub-tank 83.

[0063] The waste liquid tank 12 is connected to the downstream end in the ink flow direction of the waste liquid flow path 97. That is, the waste liquid containing ink is sent to the waste liquid tank 12 via the first sub-tank 83 and the waste liquid flow path 97.

[0064] The waste liquid pump 13 is disposed upstream of the waste liquid tank 12 in the ink flow direction of the waste liquid flow path 97. The waste liquid pump 13 moves ink to the waste liquid tank 12 via the waste liquid flow path 97.

[0065] According to the above configuration, when replacing with a different ink, the ink in the ink supply unit 8 can be discarded into the waste liquid tank 12. Therefore, in the inkjet recording device 1, the efficiency of ink replacement can be improved, and it is possible to more effectively reduce the amount of ink consumed during replacement and shorten the required time.

[0066] The waste liquid flow path 97 also includes an opening / closing mechanism 98. The opening / closing mechanism 98 opens and closes the flow of ink in the waste liquid flow path 97. The opening / closing mechanism 98 is configured, for example, as an electromagnetic two-way valve, and its opening and closing is controlled by the control unit 7. With this configuration, the waste liquid flow path 97 can be closed by the opening / closing mechanism 98 when recording on the paper S. This makes it possible to effectively reduce ink consumption.

[0067] Although the embodiments of the present invention have been described above, the scope of the present invention is not limited to these, and various modifications can be made without departing from the spirit of the invention. [Industrial Applicability]

[0068] The present invention can be used in inkjet recording apparatuses.

Claims

1. one or more print heads each having a plurality of nozzles for ejecting ink onto a print medium; an ink container that contains the ink to be supplied to the recording head; a first sub-tank that temporarily stores the ink supplied from the ink container; a second sub-tank that temporarily stores the ink supplied from the first sub-tank; a circulation pump that moves the ink from the first sub-tank to the second sub-tank; a pressurizing unit that applies pressure to the second sub-tank and supplies the ink from the second sub-tank to the recording head; a pressure reducing unit that reduces the pressure inside the first sub-tank and circulates the ink from the print head to the first sub-tank; a syringe into which the ink flows from the second sub-tank and flows out toward the recording head, and which is capable of applying a maintenance pressure to the ink that is higher than the recording pressure applied by the pressurizing unit; a first flow path through which the ink flows from the first sub-tank to the recording head via the circulation pump, the second sub-tank, and the syringe; a second flow path through which the ink circulates from the recording head to the first sub-tank; a third flow path connecting the upstream side of the recording head in the ink flow direction of the first flow path to the downstream side of the recording head in the ink flow direction of the second flow path; an intermediate flow path connected to a downstream portion of the first flow path in the ink flow direction and communicating with the recording head and the second flow path; a communication flow path including a first branch flow path that supplies the ink from the intermediate flow path to the recording head, a second branch flow path that circulates the ink from the recording head to the second flow path, and a third branch flow path that distributes the ink from the intermediate flow path to the second flow path; Equipped with an ink jet recording apparatus, characterized in that the third flow path and the first branch flow path, the second branch flow path, and the third branch flow path that constitute the communication flow path each include an on-off valve;

2. a waste liquid flow path connected to one of the first sub-tank and the second sub-tank; a waste liquid tank connected to a downstream end of the waste liquid flow path in the ink flow direction; a waste liquid pump that moves the ink to the waste liquid tank through the waste liquid flow path; 2. The inkjet recording apparatus according to claim 1, further comprising:

3. 3. The ink jet recording apparatus according to claim 2, wherein the waste liquid flow path includes an opening and closing mechanism.

4. The pressure applying unit is a pressurizing chamber communicating with the second sub-tank; a pressure pump that introduces air into the pressure chamber to pressurize it; a pressure sensor for detecting the pressure in the pressure chamber; Equipped with The pressure reducing section is a decompression chamber communicating with the first sub-tank; a decompression pump that causes air to flow out of the decompression chamber and reduce the pressure; a decompression sensor for detecting the pressure in the decompression chamber; 2. The inkjet recording apparatus according to claim 1, further comprising:

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