Liquid supply device, control method for liquid supply device, printing device

Abstract

Provided are a liquid supply device, a method for controlling a liquid supply device, and a printing device that have no adverse effect on ejection with a contaminated liquid and effectively prevent sinking. A sequence including first processing and second processing is performed. The first processing causes a liquid inside a first flow path including at least a part of a circulation flow path that supplies the liquid from a liquid tank to the liquid ejection head and collects the liquid from the liquid ejection head into the liquid tank to generate a positive flow in a first direction. The second processing causes the liquid inside the first flow path to generate a negative flow in the direction opposite to the first direction. In the first flow path, a filter that removes foreign matter inside the liquid of the positive flow from the liquid tank to the liquid ejection head is arranged, the flow rate of the liquid of the positive flow is greater than that of the liquid of the negative flow, and the negative flow has a steady flow state.

Description

Technical Field

[0001] The present invention relates to a liquid supply device, a control method for the liquid supply device, and a printing device, and particularly relates to a technique for preventing sedimentation of inclusions in a liquid in a flow path.

Background Art

[0002] In an inkjet recording device, it is important to stabilize the ejection of ink from a recording head. To stabilize the ejection of ink, an inkjet recording device is known that circulates ink through a circulation flow path provided between an ink tank and a recording head to remove foreign matter and prevent sedimentation of pigments.

[0003] Furthermore, a technique for performing maintenance by changing the flow direction of ink in a circulation flow path in the reverse direction is known. For example, Patent Documents 1 and 2 describe a technique for changing the flow direction of ink by changing the rotation direction of a pump.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0005] However, Patent Documents 1 and 2 are techniques for removing bubbles in a circulation flow path and cannot prevent sedimentation of pigments in ink. In addition, there is a problem that if the ink is flowed in the reverse direction without consideration, the contaminated ink may have an adverse effect on ejection.

[0006] The present invention has been made in view of such circumstances, and an object thereof is to provide a liquid supply device, a control method for the liquid supply device, and a printing device that do not adversely affect the ejection of contaminated liquid and effectively prevent sedimentation.

Means for Solving the Problems

[0007] One aspect of a liquid supply device for achieving the above object is a circulation flow path that supplies liquid from a liquid tank that stores liquid to a liquid ejection head and recovers liquid from the liquid ejection head to the liquid tank, a pump provided in the circulation flow path that generates a flow in the liquid in the circulation flow path, a memory that stores instructions for causing a processor to execute, and a processor that executes the instructions stored in the memory. The processor performs a first process of generating a positive flow in the first direction in the liquid in the first flow path including at least a part of the circulation flow path and a second process of generating a negative flow in the direction opposite to the first direction in the liquid in the first flow path by controlling the pump. The first flow path is provided with a filter that removes foreign substances in the liquid between the liquid tank with positive flow and the liquid ejection head. The flow rate of the liquid with positive flow is larger than the flow rate of the liquid with negative flow, and the negative flow has a steady flow state. This is a liquid supply device.

[0008] According to this aspect, a sequence including a first process of generating a positive flow and a second process of generating a negative flow in the liquid in the first flow path is performed. The first flow path is provided with a filter that removes foreign substances in the liquid between the liquid tank with positive flow and the liquid ejection head. The flow rate of the liquid with positive flow is larger than the flow rate of the liquid with negative flow, and the negative flow has a steady flow state. Therefore, contaminated liquid does not adversely affect ejection, and sedimentation can be effectively prevented.

[0009] Preferably, the first flow path is not provided with a filter that removes foreign substances in the liquid between the liquid tank with negative flow and the liquid ejection head. This aspect is suitable even when a filter is not provided between the liquid tank with negative flow and the liquid ejection head.

[0010] The processor preferably performs the sequence multiple times. By performing the negative flow multiple times, it is possible to suppress the return of the contaminated liquid while accumulating the total flow rate of the negative flow, so that the prevention of sedimentation in the liquid becomes more effective.

[0011] The first flow path preferably includes a second flow path different from the circulation flow path. By performing the sequence for the flow path where the liquid does not circulate, sedimentation can be effectively prevented.

[0012] The flow rate of the liquid in the negative flow is preferably smaller than the volume of the second flow path. This can prevent the contaminated liquid in the second flow path from diffusing into the first flow path due to the negative flow.

[0013] Before performing the sequence, the processor preferably controls the pump to replace the liquid in the second flow path with the liquid from which foreign matters have been removed by the filter. In this way, it is possible to prevent the contaminated liquid from diffusing into the first flow path due to the negative flow.

[0014] After performing the sequence, the processor preferably controls the pump to replace the liquid in all the flow paths through which the liquid in the negative flow has flowed in the first flow path with the liquid from which foreign matters have been removed by the filter. Thereby, the normal operation can be started in an appropriate state.

[0015] One aspect of the printing apparatus for achieving the above object includes a liquid tank for storing liquid, a liquid discharge head for discharging liquid from a discharge port, a moving mechanism for relatively moving the liquid discharge head and a printing substrate, and the above liquid supply device. The processor is a printing apparatus that discharges liquid from the discharge port of the liquid discharge head while relatively moving the liquid discharge head and the printing substrate to print an image on the printing substrate, circulates the liquid in the circulation flow path during printing, and performs a sequence during non-printing times other than printing times.

[0016] According to this aspect, it is possible to supply a liquid during printing and prevent sedimentation in the first flow path during non-printing.

[0017] The volume flow rate of the forward flow is preferably at least temporarily larger than the volume flow rate during printing. Thereby, sedimentation in the first flow path can be prevented by the forward flow.

[0018] The volume flow rate of the reverse flow is preferably at least temporarily larger than the volume flow rate during printing. Thereby, sedimentation in the first flow path can be prevented by the reverse flow.

[0019] The liquid preferably has a dispersed particle diameter exceeding 100 nm. This aspect is suitable when supplying a liquid in which particles tend to sediment.

[0020] The liquid is preferably white ink containing a titanium oxide material. This aspect is suitable when supplying white ink containing a titanium oxide material for which pigment sedimentation is a problem.

[0021] The circulation flow path preferably includes a valve for opening and closing a part of the flow path in the circulation flow path, and the processor controls the valve to determine the first flow path. Thereby, a desired flow path can be set as the first flow path.

[0022] One aspect of a control method for a liquid supply device for achieving the above object is a control method for a liquid supply device including a circulation flow path that supplies liquid from a liquid tank storing the liquid to a liquid discharge head and recovers the liquid from the liquid discharge head to the liquid tank, and a pump provided in the circulation flow path that generates a flow in the liquid in the circulation flow path. By controlling the pump, a first process of generating a positive flow in the first direction in the liquid in at least a part of the circulation flow path including the first flow path, and a second process of generating a negative flow in the direction opposite to the first direction in the liquid in the first flow path are included. A sequence is implemented. The first flow path has a filter for removing foreign substances in the liquid disposed between the liquid tank with a positive flow and the liquid discharge head. The flow rate of the liquid with a positive flow is larger than the flow rate of the liquid with a negative flow, and the negative flow has a steady flow state. This is a control method for a liquid supply device.

[0023] According to this aspect, a sequence including a first process of generating a positive flow and a second process of generating a negative flow in the liquid in the first flow path is implemented. The first flow path has a filter for removing foreign substances in the liquid disposed between the liquid tank with a positive flow and the liquid discharge head. The flow rate of the liquid with a positive flow is larger than the flow rate of the liquid with a negative flow, and the negative flow has a steady flow state. Thus, the contaminated liquid does not adversely affect the discharge, and sedimentation can be effectively prevented.

Effects of the Invention

[0024] According to the present invention, the contaminated liquid does not adversely affect the discharge, and sedimentation can be effectively prevented.

Brief Description of the Drawings

[0025]

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DETAILED DESCRIPTION OF THE INVENTION

[0026] Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.

[0027] 〔Overall Configuration of Ink Supply Device〕 FIG. 1 is a diagram showing the overall configuration of an ink supply device 10 (an example of a liquid supply device). The ink supply device 10 is a device that supplies ink from a buffer tank 12 to an inkjet bar 14, and as shown in FIG. 1, includes a supply flow path 16 and a recovery flow path 18.

[0028] The buffer tank 12 (an example of a liquid tank) is an ink storage means in which ink (an example of a liquid) for supplying to the inkjet bar 14 is stored.

[0029] The inkjet bar 14 (an example of a liquid discharge head) includes n head modules 15 (15-1, 15-2,..., 15-n) each provided with a plurality of nozzles 202 (see FIG. 17) for discharging ink. The n head modules 15 are connected together in one direction. Each head module 15 has an ink supply port 15A and an ink discharge port 15B, respectively.

[0030] The supply flow path 16 communicates the buffer tank 12 and the inkjet bar 14. The recovery flow path 18 communicates the inkjet bar 14 and the buffer tank 12. The ink stored in the buffer tank 12 is supplied to the inkjet bar 14 through the supply flow path 16. Also, the ink not used in the inkjet bar 14 is recovered to the buffer tank 12 through the recovery flow path 18.

[0031] The supply flow path 16 and the recovery flow path 18 are configured to include, for example, tubes. The supply flow path 16 and the recovery flow path 18 are appropriately connected to each component by a joint F.

[0032] The supply flow path 16 is provided with a degassing module 22, a supply pump 24, a supply side filter 26, and a heat exchanger 28. Further, inside the inkjet bar 14 of the supply flow path 16, a supply side back pressure tank 30, a supply side head manifold 32, a supply side pressure sensor 34, supply valves 36 (36-1, 36-2, …, 36-n), and supply dampers 38 (38-1, 38-2, …, 38-n) are provided.

[0033] Also, the recovery flow path 18 is provided with a recovery pump 50 and a recovery flow path valve 52. Further, inside the inkjet bar 14 of the recovery flow path 18, recovery dampers 40 (40-1, 40-2, …, 40-n), recovery valves 42 (42-1, 42-2, …, 42-n), a recovery side head manifold 44, a recovery side pressure sensor 46, and a recovery side back pressure tank 48 are provided.

[0034] The degassing module 22 performs degassing treatment of the ink. The supply pump 24 applies pressure to the ink inside the supply flow path 16 to generate a flow of the ink inside the supply flow path 16. The supply pump 24 is, for example, a tube pump. The supply side filter 26 removes air bubbles and foreign matter in the ink. The heat exchanger 28 adjusts the temperature of the ink.

[0035] The supply side back pressure tank 30 is a pressure buffer device that performs pressure adjustment to suppress fluctuations in the internal pressure of the supply flow path 16. The supply side back pressure tank 30 has a liquid chamber 30C communicating with the supply flow path 16 via an ink inlet 30A and an ink outlet 30B, a gas chamber 30D in which gas is stored, an elastic membrane 30E separating the liquid chamber 30C and the gas chamber 30D, a bubble discharge port 30F provided in the liquid chamber 30C, and an air flow path communication port 30G provided in the gas chamber 30D.

[0036] The ink inlet 30A communicates with the heat exchanger 28. The ink outlet 30B communicates with the supply-side head manifold 32. When ink flows into the liquid chamber 30C from the ink inlet 30A, the elastic membrane 30E deforms toward the air chamber 30D according to the volume of the ink that has flowed in. As a result, the volume of the ink flowing out from the ink outlet 30B does not fluctuate. Therefore, the pressure fluctuation in the supply flow path 16 can be suppressed. That is, the supply-side backpressure tank 30 has a pressure buffering function of suppressing the internal pressure fluctuation of the supply flow path 16 due to the internal pressure fluctuation of the inkjet bar 14 and the pulsating flow from the operation of the supply pump 24.

[0037] The air bubble discharge port 30F communicates with the drain flow path 54. The drain flow path 54 communicates the air bubble discharge port 30F and the buffer tank 12. The drain flow path 54 is a flow path for forcibly discharging the ink in the liquid chamber 30C. A drain valve 56 for switching between the communication (open state) and the interruption (closed state) between the air bubble discharge port 30F and the buffer tank 12 is provided in the drain flow path 54. When the drain valve 56 is in the open state, the ink in the liquid chamber 30C is sent to the buffer tank 12.

[0038] Further, the supply-side backpressure tank 30 includes an air flow path 58, an air connection valve 59, an air tank 60, an atmosphere communication path 61, and an air valve 62 as a gas elasticity adjustment unit for determining the pressure buffering performance of the supply-side backpressure tank 30. The air flow path communication port 30G communicates with the air flow path 58. The air connection valve 59 is an air flow path opening / closing means for switching between the communication and the interruption of the air flow path 58, and the air chamber 30D communicates with the air tank 60 via the air connection valve 59.

[0039] Further, an air valve 62 for switching between the communication and the interruption of the atmosphere communication path 61 is provided in the atmosphere communication path 61, and the air tank 60 communicates with the atmosphere via the atmosphere communication path 61.

[0040] The air connection valve 59 uses a normally open electromagnetic valve. Also, the air valve 62 is applied with a normally closed electromagnetic valve so that ink does not leak from the inkjet bar 14 even when the power is cut off when the emergency stop function is activated or the like.

[0041] The air chamber 30D communicates with the air tank 60 by opening the air connection valve 59, and the volume of the air chamber 30D can be increased according to the pressure control of the ink feeding. Further, by opening the air valve 62, the air tank 60 and the air chamber 30D can be made to communicate with the atmosphere. The air tank 60 functions as a buffer tank for the air chamber 30D.

[0042] The supply-side head manifold 32 and the recovery-side head manifold 44 are temporary storage parts for ink. The supply-side head manifold 32 and the recovery-side head manifold 44 are communicated by a first bypass flow path 64 and a second bypass flow path 66. A first bypass flow path valve 68 is provided in the first bypass flow path 64, and a second bypass flow path valve 69 is provided in the second bypass flow path 66, respectively.

[0043] The supply-side pressure sensor 34 is pressure measurement means for measuring and outputting the internal pressure of the supply flow path 16. Also, the recovery-side pressure sensor 46 is pressure measurement means for measuring and outputting the internal pressure of the recovery flow path 18. Sensors such as a semiconductor piezoresistive method, a capacitance method, and a silicon resonant method can be applied to the supply-side pressure sensor 34 and the recovery-side pressure sensor 46.

[0044] The head module 15 includes an ink supply port 15A and an ink discharge port 15B. Each ink supply port 15A of the head modules 15-1, 15-2, …, 15-n communicates with the supply-side head manifold 32 via supply valves 36-1, 36-2, …, 36-n, respectively. Also, each ink discharge port 15B of the head modules 15-1, 15-2, …, 15-n communicates with the recovery-side head manifold 44 via recovery valves 42-1, 42-2, …, 42-n, respectively.

[0045] The supply valves 36 (36-1, 36-2, …, 36-n) are flow path opening / closing means for switching between communication and blockage of the supply flow path 16. The recovery valves 42 (42-1, 42-2, …, 42-n) are flow path opening / closing means for switching between communication and blockage of the recovery flow path 18. The supply valves 36 and the recovery valves 42 are normal-closed type (or latch type) electromagnetic valves whose opening and closing are controlled by a control signal, and are configured such that ink does not leak from the head module 15 even when the power supply is cut off, such as when the emergency stop function is activated.

[0046] Supply dampers 38-1, 38-2, …, 38-n are respectively provided between the supply valves 36-1, 36-2, …, 36-n and the respective ink supply ports 15A. Also, recovery dampers 40-1, 40-2, …, 40-n are respectively provided between the recovery valves 42-1, 42-2, …, 42-n and the respective ink discharge ports 15B. The supply dampers 38 and the recovery dampers 40 are pressure buffering means for suppressing the pulsation of ink generated by the ejection operation of the inkjet bar 14.

[0047] The recovery-side back pressure tank 48 is a pressure buffering device that performs pressure adjustment so as to suppress fluctuations in the internal pressure of the recovery flow path 18, and is configured in the same manner as the supply-side back pressure tank 30.

[0048] That is, the recovery-side back pressure tank 48 has a liquid chamber 48C that communicates with the recovery flow path 18 via an ink inlet 48A and an ink outlet 48B, a gas chamber 48D in which gas is stored, an elastic membrane 48E that separates the liquid chamber 48C and the gas chamber 48D, a bubble discharge port 48F provided in the liquid chamber 48C, and an air flow path communication port 48G provided in the gas chamber 48D. The bubble discharge port 48F communicates with the buffer tank 12 via a drain flow path 54 provided with a drain valve 70. The air flow path communication port 48G communicates with the atmosphere communication path 74 via an air flow path 71, an air connection valve 72, an air tank 73, and an air valve 75.

[0049] The recovery pump 50 applies pressure to the ink inside the recovery flow path 18 and generates a flow in the ink inside the recovery flow path 18. The recovery pump 50 is, for example, a tube pump. The recovery flow path valve 52 is a flow path opening / closing means for switching between communication and cutoff between the recovery pump 50 and the buffer tank 12.

[0050] Further, the ink supply device 10 includes an ink main tank 76, a replenishment flow path 78, an overflow flow path 80, and a replenishment pump 82.

[0051] The ink main tank 76 is an ink storage means in which ink for supplying to the buffer tank 12 is stored. The replenishment flow path 78 communicates the ink main tank 76 and the buffer tank 12. The overflow flow path 80 communicates the buffer tank 12 and the ink main tank 76.

[0052] The replenishment pump 82 applies pressure to the ink inside the replenishment flow path 78 and generates a flow in the ink inside the replenishment flow path 78. The replenishment pump 82 is, for example, a tube pump. When the replenishment pump 82 is driven, the buffer tank 12 is replenished with ink from the ink main tank 76. Note that a main tank filter 76A is provided at the end of the replenishment flow path 78 on the ink main tank 76 side, and the buffer tank 12 is replenished with ink from which foreign matter has been removed by the main tank filter 76A. Also, when over-replenishing, the ink is returned from the buffer tank 12 to the ink main tank 76.

[0053] Furthermore, the ink supply device 10 includes a first safety valve 84, a second safety valve 86, a third safety valve 88, a recovery side filter 90, and a recovery side filter valve 92.

[0054] When the internal pressure of the supply flow path 16 in the ink supply device 10 rises above a predetermined value, the first safety valve 84 and the second safety valve 86 operate to lower the internal pressure of the supply flow path 16. Also, when the internal pressure of the recovery flow path 18 in the ink supply device 10 rises above a predetermined value, the third safety valve 88 operates to lower the internal pressure of the recovery flow path 18.

[0055] The recovery-side filter valve 92 is a flow path opening and closing means for switching between communication and cutoff between the recovery pump 50 and the degassing module 22. By setting the recovery-side filter valve 92 to the open state, the ink supply device 10 can pass the ink that has passed through the degassing module 22 through the recovery-side filter 90.

[0056] FIG. 2 is a block diagram showing the configuration of the control system of the ink supply device 10. As shown in FIG. 2, the ink supply device 10 includes a general control unit 94, a valve control unit 97, and a pump control unit 98.

[0057] The general control unit 94 comprehensively controls the operation of the ink supply device 10 by controlling the valve control unit 97 and the pump control unit 98 respectively. The general control unit 94 includes a processor 95 and a memory 96.

[0058] The processor 95 executes the instructions stored in the memory 96. The hardware structure of the processor 95 is various processors as shown below. The various processors include a CPU (Central Processing Unit) which is a general-purpose processor that executes software (program) and acts as various functional units, a GPU (Graphics Processing Unit) which is a processor specialized for image processing, a PLD (Programmable Logic Device) which is a processor such as an FPGA (Field Programmable Gate Array) whose circuit configuration can be changed after manufacturing, and a dedicated electric circuit which is a processor having a circuit configuration specifically designed to execute specific processing such as an ASIC (Application Specific Integrated Circuit).

[0059] One processing unit may be composed of one of these various processors, or may be composed of two or more processors of the same or different types (for example, a plurality of FPGAs, or a combination of a CPU and an FPGA, or a combination of a CPU and a GPU). Also, a plurality of functional units may be composed of one processor. As an example of configuring a plurality of functional units with one processor, first, as represented by a computer such as a client or a server, one processor is configured by a combination of one or more CPUs and software, and this processor acts as a plurality of functional units. Second, as represented by an SoC (System On Chip), there is a form in which a processor that realizes the functions of the entire system including a plurality of functional units with one IC (Integrated Circuit) chip is used. Thus, various functional units are configured using one or more of the above various processors as a hardware structure.

[0060] Furthermore, the hardware structure of these various processors is more specifically an electrical circuit (circuitry) that combines circuit elements such as semiconductor elements.

[0061] The memory 96 stores instructions for the processor 95 to execute. The memory 96 includes a RAM (Random Access Memory) and a ROM (Read Only Memory) not shown. The processor 95 uses the RAM as a working area, executes software using various programs and parameters including the control program of the ink supply device 10 stored in the ROM, and executes various processes of the ink supply device 10 by using the parameters stored in the ROM and the like.

[0062] The valve control unit 97 controls the open and closed states of the supply valve 36, the recovery valve 42, the recovery flow path valve 52, the drain valve 56, the first bypass flow path valve 68, the second bypass flow path valve 69, the drain valve 70, and the recovery side filter valve 92. The valve control unit 97 may control the open and closed states of the air connect valve 59, the air valve 62, the air connect valve 72, and the air valve 75.

[0063] The pump control unit 98 controls the operations of the supply pump 24, the recovery pump 50, and the replenishment pump 82.

[0064] Figure 3 is a diagram showing the flow of ink during the normal operation of the ink supply device 10. As shown in Figure 3, the circulation flow path 20 through which ink circulates during normal operation is composed of the supply flow path 16 and the recovery flow path 18. That is, the circulation flow path 20 is a flow path connecting the buffer tank 12, the deaeration module 22, the supply pump 24, the supply side filter 26, the heat exchanger 28, the supply side back pressure tank 30, the supply side head manifold 32, the first bypass flow path valve 68, the second bypass flow path valve 69, the supply valve 36, the supply damper 38, the head module 15, the recovery valve 42, the recovery side head manifold 44, the recovery side back pressure tank 48, the recovery pump 50, the recovery flow path valve 52, and the buffer tank 12.

[0065] In Figure 3, the shaded valves indicate that they are in the closed state. That is, during normal operation, the valve control unit 97 closes the drain valve 56, the drain valve 70, and the recovery side filter valve 92, and opens the supply valve 36, the recovery valve 42, the recovery flow path valve 52, the first bypass flow path valve 68, and the second bypass flow path valve 69. Also, during normal operation, the pump control unit 98 rotates the supply pump 24 and the recovery pump 50 in the positive direction. Thereby, the ink supply device 10 circulates ink between the buffer tank 12 and the ink jet bar 14 through the circulation flow path 20 as indicated by the arrows in Figure 3.

[0066] That is, the ink that exits the buffer tank 12 first passes through the degassing module 22 to remove the dissolved air in the ink. The ink from which the dissolved air has been removed and that has passed through the supply pump 24 then passes through the supply-side filter 26 to remove foreign matter in the ink. The ink from which the foreign matter has been removed passes through the heat exchanger 28 to have its temperature adjusted. The ink with the adjusted temperature passes through the supply-side back-pressure tank 30, thereby suppressing fluctuations in the internal pressure of the supply flow path 16. The ink that has passed through the supply-side back-pressure tank 30 is supplied to the head module 15 via the supply-side head manifold 32.

[0067] The ink supplied to the head module 15 may be ejected from the nozzles 202 (see FIG. 17) as necessary. The ink that has not been ejected from the nozzles 202 is recovered from the head module 15 to the recovery-side head manifold 44.

[0068] Also, a part of the ink that has passed through the supply-side back-pressure tank 30 is recovered from the supply-side head manifold 32 to the recovery-side head manifold 44 via the first bypass flow path 64 and the second bypass flow path 66.

[0069] The ink recovered to the recovery-side head manifold 44 passes through the recovery-side back-pressure tank 48, thereby suppressing fluctuations in the internal pressure of the recovery flow path 18. The ink that has passed through the recovery-side back-pressure tank 48 passes through the recovery pump 50 and the recovery flow path valve 52 and returns to the buffer tank 12.

[0070] The ink stored in the buffer tank 12 of the ink supply device 10 is usually contaminated. This is because foreign matter can enter the ink supplied from the ink main tank 76, and pigment sedimentation occurs while the ink is left in the buffer tank 12 for a long time. As shown in FIG. 3, the ink supply device 10 can prevent the contaminated ink from spreading inside the circulation flow path 20 by passing the ink through the supply-side filter 26 during normal operation.

[0071] In this embodiment, tube pumps are applied as the supply pump 24 and the recovery pump 50, but other types of pumps such as diaphragm pumps may be applied. The supply pump 24 and the recovery pump 50 each read the measured values of the supply-side pressure sensor 34 and the recovery-side pressure sensor 46, and control the rotational speed by PID control or the like so as to obtain an appropriate pressure.

[0072] Also, in this embodiment, the ink circulation path is configured such that the ink circulates inside the head module 15 during normal operation. However, at least one of the supply valve 36 and the recovery valve 42 may be closed, and only the supply-side head manifold 32 and the recovery-side head manifold 44 may be circulated. Also, instead of constantly circulating the ink during normal operation, it may be circulated intermittently.

[0073] 〔First Embodiment〕 FIGS. 4 and 5 are diagrams showing the flow of ink in the maintenance operation according to the first embodiment of the ink supply device 10.

[0074] The ink supply device 10 performs a stirring sequence including a first process of generating a positive flow in the first direction in the ink in the stirring flow path 99A (an example of the first flow path) including at least a part of the circulation flow path 20 and a second process of generating a negative flow in the ink in the stirring flow path 99A in a direction opposite to the first direction, at least in the maintenance operation.

[0075] As shown in FIGS. 4 and 5, the stirring flow path 99A is a flow path connecting the buffer tank 12, the degassing module 22, the supply pump 24, the supply-side filter 26, the heat exchanger 28, the supply-side back-pressure tank 30, the supply-side head manifold 32, the first bypass flow path 64 and the second bypass flow path 66, the recovery-side head manifold 44, the recovery-side back-pressure tank 48, the recovery pump 50, the recovery flow path valve 52, and the buffer tank 12.

[0076] In FIGS. 4 and 5, the filled valve indicates that it is in the closed state. That is, in the maintenance operation, the valve control unit 97 closes the supply valve 36, the recovery valve 42, the drain valve 56, the drain valve 70, and the recovery-side filter valve 92, and opens the recovery flow path valve 52, the first bypass flow path valve 68, and the second bypass flow path valve 69.

[0077] The normal flow of the first process is, as shown by the arrow in FIG. 4, the flow in the first direction in which the ink in the buffer tank 12 returns to the buffer tank 12 via the degassing module 22, the supply pump 24, the supply-side filter 26, the heat exchanger 28, the supply-side back pressure tank 30, the supply-side head manifold 32, the first bypass flow path 64 and the second bypass flow path 66, the recovery-side head manifold 44, the recovery-side back pressure tank 48, the recovery pump 50, and the recovery flow path valve 52. The agitation flow path 99A has the supply-side filter 26 disposed between the buffer tank 12 of the normal flow and the inkjet bar 14. The pump control unit 98 rotates the supply pump 24 and the recovery pump 50 in the positive direction in the first process.

[0078] Assuming the normal flow ink volume velocity is U1 and the flowing time is T1, the ink volume flowing during the normal flow (the flow rate of the normal flow ink) V1 can be expressed as V1 = U1 × T1. It is desirable to limit the normal flow to the circulation of the supply-side head manifold 32 and the recovery-side head manifold 44 by closing the supply valve 36 and the recovery valve 42. This can reduce the possibility that foreign substances generated by the ink flow different from the normal operation flow into the head module 15. Also, even when generating a normal flow at a flow rate different from the normal operation, it becomes easy to control the nozzle meniscus of the head module 15 to an appropriate pressure.

[0079] Also, as shown by the arrows in FIG. 5, the negative flow of the second process is the flow in the direction opposite to the first direction in which the ink in the buffer tank 12 returns to the buffer tank 12 via the recovery channel valve 52, the recovery pump 50, the recovery-side backpressure tank 48, the recovery-side head manifold 44, the first bypass channel 64 and the second bypass channel 66, the supply-side head manifold 32, the supply-side backpressure tank 30, the heat exchanger 28, the supply-side filter 26, the supply pump 24, and the deaeration module 22. The agitation channel 99A has no filter disposed between the buffer tank 12 with negative flow and the inkjet bar 14, that is, no filter is disposed. The pump control unit 98 rotates the supply pump 24 and the recovery pump 50 in the negative direction in the second process.

[0080] Assuming that the negative ink volume velocity is U2 and the flowing time is T2, the ink volume flowing during negative flow (the flow rate of the negative-flow ink) V2 can be expressed as V2 = U2 × T2. Also for negative flow, it is desirable to stop at the circulation of the supply-side head manifold 32 and the recovery-side head manifold 44 by closing the supply valve 36 and the recovery valve 42.

[0081] When generating negative flow of ink as shown in FIG. 5, ink that has not passed through the supply-side filter 26 can flow into the inside of the inkjet bar 14. Therefore, it is preferable that V1 > V2 until the next normal operation starts, where V1 is the ink volume flowing during positive flow and V2 is the ink volume flowing during negative flow. That is, it is preferable that the flow rate of the positive-flow ink in the first process is greater than the flow rate of the negative-flow ink in the second process.

[0082] Positive flow and negative flow can be realized by alternately switching the rotation direction of the tube pumps applied to the supply pump 24 and the recovery pump 50. Since it is desirable to reduce the load on the tube pumps and the ink flow has inertia, it is desirable to insert a waiting time of about 1 second before changing the direction of the ink flow. However, this depends on the channel design and the pump capacity, so it cannot be generally stated and depends on the design.

[0083] Note that the negative flow needs to have a steady flow state for at least a certain period of time. Therefore, the time T2 for generating the negative flow needs to ensure that it is longer than the time when the negative flow becomes a steady flow. FIGS. 6 and 7 are diagrams showing the time change of the ink flow velocity of a certain flow path after driving the supply pump 24 and the recovery pump 50 in the negative direction. In FIGS. 6 and 7, the horizontal axis represents time, and the vertical axis represents the ink flow velocity.

[0084] In the case shown in FIG. 6, the ink flow velocity gradually increases from the timing T0 when the driving of the supply pump 24 and the recovery pump 50 is started, and becomes the velocity of the steady flow at the timing T S . In this case, the time until it becomes a steady flow is T S - T0, and the time T2 for generating the negative flow is set so as to satisfy T2 > T S - T0.

[0085] In the case shown in FIG. 7, the ink flow velocity gradually increases from the timing T0 when the driving of the supply pump 24 and the recovery pump 50 is started, then decreases, and then becomes the velocity of the steady flow at the timing T S . In this case, the time until it becomes a steady flow is also T S - T0, and the time T2 for generating the negative flow is set so as to satisfy T2 > T S - T0.

[0086] Depending on the flow path design, it may take several seconds or more until the ink becomes a steady flow after the pump is driven. This is because the ink flow path system has a pressure loss component, an inertia component, and an acoustic capacitance component. Especially for the tubes far from the pump, with only a short-time pump drive, the ink flow and pressure due to the negative flow do not occur as expected, and foreign substances including pigment precipitates, which are expected as the effect of the negative flow, cannot be moved. According to this embodiment, since the negative flow has a steady flow state for at least a certain period of time, pigment precipitates and foreign substances can be effectively removed.

[0087] FIG. 8 is a flowchart showing the processing of the control method during the maintenance operation of the ink supply device 10. The processor 95 reads out and executes the control program of the ink supply device 10 from the memory 96. The control program may be stored and provided in a non-transitory storage medium, or may be provided via a network (not shown).

[0088] In step S1, the valve control unit 97 controls the supply valve 36, the recovery valve 42, the recovery flow path valve 52, the drain valve 56, the first bypass flow path valve 68, the second bypass flow path valve 69, the drain valve 70, and the recovery side filter valve 92 to determine the ink flow path.

[0089] Here, the valve control unit 97 closes the supply valve 36, the recovery valve 42, the drain valve 56, the drain valve 70, and the recovery side filter valve 92, and opens the recovery flow path valve 52, the first bypass flow path valve 68, and the second bypass flow path valve 69 to generate the agitation flow path 99A shown in FIGS. 4 and 5.

[0090] Step S2 is a process of generating a forward flow in the ink inside the agitation flow path 99A before performing the agitation sequence. In step S2, the pump control unit 98 controls the supply pump 24 and the recovery pump 50 to generate a forward flow in the ink inside the agitation flow path 99A. Here, the pump control unit 98 rotates the supply pump 24 and the recovery pump 50 in the positive direction to flow an ink volume larger than the volume of the circulation flow path 20. In this way, it is preferable to generate a forward flow before starting the negative flow, which is the second process, and replace the ink inside the agitation flow path 99A with fresh ink that has passed through the supply side filter 26.

[0091] In step S3, the processor 95 executes the second process in the stirring sequence. That is, the pump control unit 98 controls the supply pump 24 and the recovery pump 50 to generate a negative flow having a steady flow state in the ink inside the stirring flow path 99A for at least a certain period of time. Here, the pump control unit 98 rotates the supply pump 24 and the recovery pump 50 in the negative direction, and flows the ink of the ink volume V2 at the ink volume velocity U2.

[0092] The ink volume velocity U2 is faster than the ink volume velocity U0 during normal operation. Thereby, pigment precipitates and foreign matters in the ink that are difficult to remove can be effectively removed.

[0093] In step S4, the processor 95 executes the first process in the stirring sequence. That is, the pump control unit 98 controls the supply pump 24 and the recovery pump 50 to generate a positive flow in the ink inside the stirring flow path 99A. Here, the pump control unit 98 rotates the supply pump 24 and the recovery pump 50 in the positive direction, and flows the ink of the ink volume V1 at the ink volume velocity U1. Here, V1 is larger than V2. Thereby, the ink in the ink jet bar 14 can be replaced with fresh ink that has passed through the supply side filter 26.

[0094] Also, the ink volume velocity U1 is faster than the ink volume velocity U0 during normal operation. Thereby, pigment precipitates and foreign matters in the ink that are difficult to remove can be effectively removed.

[0095] Thus, it is preferable that the processor 95 first performs the stirring sequence from the negative flow, which is the second process, and then performs the positive flow, which is the first process.

[0096] The processor 95 may perform the stirring sequence only once, but in this embodiment, the second process in step S3 and the first process in step S4 are repeatedly performed a plurality of times.

[0097] In this way, by repeating the negative flow in multiple portions, it is possible to suppress the return of the contaminated ink while accumulating the total flow rate of the negative flow, and the countermeasure against the pigment sedimented in the ink becomes more effective. Also, when i and n are natural numbers and the stirring sequence is repeated n times, if the ink volume flowing during the i-th positive flow is V1(i) and the ink volume flowing during the i-th negative flow is V2(i), it is preferable that V1(i)>V2(i) is satisfied for each i = 1 to n. Note that the stirring sequence may include processes other than the first process and the second process, such as a process of switching the communication and blocking of arbitrary valves and a process of stopping an arbitrary pump. That is, the stirring sequence only needs to include at least the first process and the second process.

[0098] After the stirring sequence ends, it is even better to replace the ink inside the stirring flow path 99A with fresh ink that has passed through the supply-side filter 26 by flowing an ink volume larger than the volume of the circulation flow path 20 by positive flow.

[0099] Finally, in step S5, the valve control unit 97 controls the supply valve 36, the recovery valve 42, the recovery flow path valve 52, the drain valve 56, the first bypass flow path valve 68 and the second bypass flow path valve 69, the drain valve 70, and the recovery-side filter valve 92 to end the processing of this flowchart. Here, the valve control unit 97 closes the drain valve 56, the drain valve 70, and the recovery-side filter valve 92, and opens the supply valve 36, the recovery valve 42, the recovery flow path valve 52, the first bypass flow path valve 68, and the second bypass flow path valve 69 to generate the circulation flow path 20 during normal operation shown in FIG. 3. If necessary, the pump control unit 98 may control the supply pump 24 and the recovery pump 50.

[0100] By implementing the stirring sequence as described above, it is possible to prevent the sedimentation of the pigment contained in the ink in the flow path.

[0101] 〔Second Embodiment〕 Figures 9 and 10 are diagrams showing the flow of ink in the maintenance operation according to the second embodiment of the ink supply device 10. The ink supply device 10 performs a stirring sequence including a first process of generating a forward flow in the ink in the stirring flow path 99B (an example of a first flow path) including at least a part of the circulation flow path 20 and a second process of generating a reverse flow in the ink in the stirring flow path 99B at least in the maintenance operation.

[0102] As shown in FIGS. 9 and 10, the stirring flow path 99B is a flow path connecting the buffer tank 12, the degassing module 22, the supply pump 24, the supply side filter 26, the heat exchanger 28, the supply side back pressure tank 30, the drain valve 56, and the buffer tank 12. Thus, the stirring flow path 99B does not include the supply side head manifold 32 and the recovery side head manifold 44. Further, among the stirring flow path 99B, the drain flow path 54 (an example of a second flow path) connecting the supply side back pressure tank 30, the drain valve 56, and the buffer tank 12 shown by the thick line in FIG. 10 is a flow path not used during normal operation.

[0103] In FIGS. 9 and 10, the filled valves indicate that they are in the closed state. That is, in the maintenance operation, the valve control unit 97 closes the supply valve 36, the recovery valve 42, the recovery flow path valve 52, the first bypass flow path valve 68, the second bypass flow path valve 69, the drain valve 70, and the recovery side filter valve 92, and opens the drain valve 56.

[0104] The forward flow of the first process is, as shown by the arrow in FIG. 9, the flow of the ink in the buffer tank 12 returning to the buffer tank 12 via the degassing module 22, the supply pump 24, the supply side filter 26, the heat exchanger 28, the supply side back pressure tank 30, and the drain valve 56. The supply side filter 26 is disposed between the buffer tank 12 of the forward flow and the ink jet bar 14. In the first process, the pump control unit 98 rotates the supply pump 24 in the positive direction and flows the ink of the ink volume V1 at the ink volume velocity U1.

[0105] As shown by the arrow in FIG. 10, the negative flow of the second process is the flow in which the ink in the buffer tank 12 returns to the buffer tank 12 via the drain valve 56, the supply-side back-pressure tank 30, the heat exchanger 28, the supply-side filter 26, the supply pump 24, and the degassing module 22. No filter is disposed between the buffer tank 12 with the negative flow and the inkjet bar 14. In the second process, the pump control unit 98 rotates the supply pump 24 in the negative direction and flows the ink of the ink volume V2 at the ink volume velocity U2. The negative flow has a steady flow state for at least a certain period of time.

[0106] Thus, the ink that has not passed through the filter can flow into the interior of the inkjet bar 14 in the negative flow. Therefore, similar to the first embodiment, it is preferable that the ink volumes V1 and V2 satisfy the relationship V1 > V2. Further, it is desirable that the agitation sequence is carried out not only once but also a plurality of times. Furthermore, it is preferable that the ink volume velocities U1 and U2 satisfy the relationships U1 > U0 and U2 > U0 with respect to the ink volume velocity U0 during normal operation.

[0107] Also, in the agitation sequence, ink flows into the drain channel 54 where no ink flows during normal operation. Since there are few opportunities for the ink to flow through the drain channel 54 during normal operation, the pigment is likely to settle, and the agitation sequence can prevent the pigment from settling.

[0108] Here, regarding the drain channel 54 connecting the supply-side back-pressure tank 30 and the buffer tank 12, it is desirable to replace it with fresh ink that has passed through the supply-side filter 26 before carrying out the agitation sequence. For that purpose, it is desirable to carry out the forward flow shown in FIG. 9 for a predetermined period of time.

[0109] Also, assuming that the volume of the drain channel 54 connecting the supply-side backpressure tank 30 and the buffer tank 12 is V3, it is desirable that the negative-flow ink volume V2 be smaller than the volume V3 of the drain channel 54. This can reduce the possibility that ink that has not passed through the supply-side filter 26 will flow into inappropriate areas such as inside the inkjet bar 14.

[0110] 〔Third Embodiment〕 FIGS. 11 and 12 are diagrams showing the flow of ink in the maintenance operation according to the third embodiment of the ink supply device 10. The ink supply device 10 performs a stirring sequence including a first process of generating a positive flow in the ink in the stirring channel 99C (an example of a first channel) including at least a part of the circulation channel 20 and a second process of generating a negative flow in the ink in the stirring channel 99C, at least in the maintenance operation.

[0111] As shown in FIGS. 11 and 12, the stirring channel 99C is a channel connecting the buffer tank 12, the deaeration module 22, the recovery-side filter valve 92, the recovery-side filter 90, the recovery pump 50, the recovery-side backpressure tank 48, the drain valve 70, and the buffer tank 12. Thus, the stirring channel 99C does not include the supply-side head manifold 32 and the recovery-side head manifold 44. Also, among the stirring channel 99C, the drain channel 54 (an example of a second channel) connecting the recovery-side backpressure tank 48, the drain valve 70, and the buffer tank 12, which is shown by a thick line in FIG. 12, is a channel not used during normal operation.

[0112] In FIGS. 11 and 12, the solid-colored valves indicate that they are in the closed state. That is, the valve control unit 97 closes the supply valve 36, the recovery valve 42, the recovery channel valve 52, the drain valve 56, the first bypass channel valve 68, and the second bypass channel valve 69, and opens the drain valve 70 and the recovery-side filter valve 92.

[0113] The normal flow of the first process is, as shown by the arrows in FIG. 11, the flow in which the ink in the buffer tank 12 returns to the buffer tank 12 via the degassing module 22, the recovery-side filter valve 92, the recovery-side filter 90, the recovery pump 50, the recovery-side backpressure tank 48, and the drain valve 70. The agitation flow path 99C has the recovery-side filter 90 disposed between the buffer tank 12 in the normal flow and the inkjet bar 14. In the first process, the pump control unit 98 rotates the recovery pump 50 in the negative direction and flows ink with an ink volume V1 at an ink volume velocity U1.

[0114] The negative flow of the second process is, as shown by the arrows in FIG. 12, the flow in which the ink in the buffer tank 12 returns to the buffer tank 12 via the drain valve 70, the recovery-side backpressure tank 48, the recovery pump 50, the recovery-side filter 90, the recovery-side filter valve 92, and the degassing module 22. The agitation flow path 99C has no filter disposed between the buffer tank 12 in the negative flow and the inkjet bar 14. In the second process, the pump control unit 98 rotates the recovery pump 50 in the positive direction and flows ink with an ink volume V2 at an ink volume velocity U2. The negative flow has a steady flow state for at least a certain period of time.

[0115] Thus, in the negative flow, ink that has not passed through the filter can flow into the inkjet bar 14. Therefore, as before, it is preferable that the ink volumes V1 and V2 satisfy the relationship V1 > V2. Further, it is desirable that the agitation sequence be carried out not only once but a plurality of times. Furthermore, it is preferable that the ink volume velocities U1 and U2 satisfy the relationships U1 > U0 and U2 > U0 with respect to the ink volume velocity U0 during normal operation.

[0116] Also, in the agitation sequence, ink flows into the drain flow path 54 where ink does not flow during normal operation. Since there are few opportunities for ink to flow in the drain flow path 54 during normal operation, the pigment is likely to settle, and the agitation sequence can prevent the pigment from settling.

[0117] Here, regarding the drain channel 54 connecting the recovery-side backpressure tank 48 and the buffer tank 12, it is desirable to replace it with fresh ink that has passed through the supply-side filter 26 before performing the agitation sequence. For this purpose, it is desirable to perform the forward flow shown in FIG. 11 for a predetermined time.

[0118] Also, assuming that the volume of the drain channel 54 connecting the recovery-side backpressure tank 48 and the buffer tank 12 is V4, it is desirable that the volume V2 of the ink in the reverse flow is smaller than the volume V4 of the drain channel 54. This can reduce the possibility that the ink that has not passed through the recovery-side filter 90 flows into an inappropriate area.

[0119] It is desirable to perform this sequence for all the tubes constituting the flow path, except for the tubes for ink disposal (not shown) etc. outside the flow path around the inkjet bar 14. Or, it is desirable to perform this sequence for all the tubes constituting the flow path other than the flow path around the inkjet bar 14 on the upstream side from the buffer tank 12. By doing so, the ink supply device 10 can be stably operated without the pigments and foreign substances in the ink settling in the unused tubes.

[0120] So far, an example where no filter is arranged between the buffer tank 12 and the inkjet bar 14 in the reverse flow of the agitation channels 99A, 99B, and 99C has been described, but a filter may be arranged. In this case, foreign substances accumulate on the inkjet bar 14 side of the filter during normal operation. Then, when a reverse flow occurs in the filter during the maintenance operation, the foreign substances are peeled off from the filter and flow to the inkjet bar 14 side. Therefore, regarding the point that the ink contaminated on the inkjet bar 14 side flows in the reverse flow, there are similar problems regardless of whether a filter is arranged between the buffer tank 12 and the inkjet bar 14 in the reverse flow.

[0121] 〔Fourth Embodiment〕 FIG. 13 and FIG. 14 are diagrams showing the overall configuration of the ink supply device 100 (an example of a liquid supply device) and the flow of ink in the maintenance operation. Note that the parts common to the ink supply device 10 shown in FIG. 1 are denoted by the same reference numerals, and detailed descriptions thereof are omitted.

[0122] The inkjet bar 102 has an ink flow path configuration in which ink does not circulate up to the head module 15. That is, the head module 15 includes an ink supply port 15A and does not include an ink discharge port 15B. The ink supplied to the supply side head manifold 32 is supplied to the head module 15 via the supply valve 36 and the supply damper 38.

[0123] The ink supply device 100 performs a stirring sequence including a first process of generating a positive flow in the ink in the stirring flow path 99D (an example of a first flow path) and a second process of generating a negative flow in the ink in the stirring flow path 99D, at least in the maintenance operation.

[0124] As shown in FIGS. 13 and 14, the stirring flow path 99D is a flow path connecting the buffer tank 12, the degassing module 22, the supply pump 24, the supply side filter 26, the heat exchanger 28, the supply side back pressure tank 30, the drain valve 56, and the buffer tank 12. That is, the valve control unit 97 opens the drain valve 56 during the maintenance operation.

[0125] The positive flow of the first process is a flow in which the ink in the buffer tank 12 returns to the buffer tank 12 via the degassing module 22, the supply pump 24, the supply side filter 26, the heat exchanger 28, the supply side back pressure tank 30, and the drain valve 56, as shown by the arrow in FIG. 13.

[0126] The supply side filter 26 is disposed between the buffer tank 12 of the positive flow and the inkjet bar 14 in the stirring flow path 99D. In the first process, the pump control unit 98 rotates the supply pump 24 in the positive direction and flows the ink of the ink volume V1 at the ink volume velocity U1.

[0127] As shown by the arrow in Fig. 14, the negative flow of the second process is the flow in which the ink in the buffer tank 12 returns to the buffer tank 12 via the drain valve 56, the supply-side back-pressure tank 30, the heat exchanger 28, the supply-side filter 26, the supply pump 24, and the degassing module 22. In the agitation flow path 99D, no filter is arranged between the buffer tank 12 with negative flow and the inkjet bar 14. The pump control unit 98 rotates the supply pump 24 in the negative direction in the second process and flows the ink with an ink volume V2 at an ink volume velocity U2. The negative flow has a steady flow state for at least a certain period of time.

[0128] Thus, in the negative flow, the ink flows in a steady flow from the supply-side back-pressure tank 30 to the buffer tank 12 via the heat exchanger 28, the supply-side filter 26, the supply pump 24, and the degassing module 22 in the direction opposite to that in the normal operation, and the ink that has not passed through the supply-side filter 26 can flow into the interior of the inkjet bar 14. Therefore, as before, it is preferable that the ink volumes V1 and V2 satisfy the relationship V1 > V2. Also, it is desirable to perform the agitation sequence not only once but a plurality of times. Furthermore, it is preferable that the ink volume velocities U1 and U2 satisfy the relationships U1 > U0 and U2 > U0 with respect to the ink volume velocity U0 during normal operation.

[0129] Also, in the agitation sequence, ink flows into the drain flow path 54 where no ink flows during normal operation. Since there are few opportunities for ink to flow in the drain flow path 54 during normal operation, the state is such that the pigment is likely to settle, and the agitation sequence can prevent the pigment from settling. Regarding normal operation as well, the ink may be circulated as shown in Fig. 13.

[0130] Here, regarding the drain flow path 54 connecting the supply-side back-pressure tank 30 and the buffer tank 12, it is desirable to replace it with fresh ink that has passed through the supply-side filter 26 before performing the agitation sequence. For that purpose, it is desirable to perform the forward flow shown in Fig. 13 for a predetermined period of time.

[0131] [Configuration of the Inkjet Printing Apparatus] 15 is an overall configuration diagram of an inkjet printing device 110 to which the ink supply device 10 is applied. The inkjet printing device 110 is a printing machine that prints an image on web-like paper 1 (an example of a printing substrate) by a single pass method. General-purpose printing paper is used for the paper 1. General-purpose printing paper does not refer to so-called paper specifically for inkjet printing, but refers to paper that is mainly made of cellulose, such as coated paper used in general offset printing, etc.

[0132] As shown in FIG. 15, the inkjet printing apparatus 110 includes a transport section 120, a delivery section 130, a pretreatment liquid application section 140, a printing section 150, a drying section 170, and a winding section 180.

[0133] <Transport section, delivery section, winding section> The transport section 120 transports the paper 1 along a transport path from the sending section 130 to the winding section 180. The transport section 120 includes a plurality of path rollers 122 that function as guide rollers.

[0134] The delivery section 130 includes a delivery roll 132. The delivery roll 132 includes a rotatably supported reel (not shown). The paper 1 before an image is printed is wound in a roll around the reel.

[0135] On the other hand, the winding section 180 includes a winding roll 182. The winding roll 182 includes a rotatably supported reel (not shown). One end of the paper 1 is connected to the reel. The winding roll 182 includes a winding motor (not shown) that drives the reel to rotate.

[0136] The paper 1 is transported by the transport unit 120 in a roll-to-roll manner along a transport path from the delivery roll 132 to the take-up roll 182. In this manner, the transport unit 120 functions as a movement mechanism that moves the printing unit 150 and the paper 1 relative to one another.

[0137] <Pretreatment Liquid Coating Unit> The pretreatment liquid coating unit 140 is disposed upstream of the printing unit 150 in the conveyance path. The pretreatment liquid coating unit 140 applies a pretreatment liquid to the printing surface of the sheet 1. The pretreatment liquid is a liquid containing a component that aggregates, insolubilizes, or thickens the colorant component in the aqueous ink and water, and thickens by reacting with the aqueous ink.

[0138] The pretreatment liquid coating unit 140 includes an application roller 142, a counter roller 144, and a pretreatment liquid drying unit 146. The sheet 1 conveyed from the feeding unit 130 is guided by the pass roller 122 and conveyed to a position facing the application roller 142.

[0139] The application roller 142 is rotated by a motor (not shown). The pretreatment liquid is supplied to the surface of the application roller 142 from a coater (not shown), and then the excess pretreatment liquid is scraped off by a blade (not shown). The application roller 142 sandwiches the sheet 1 between itself and the counter roller 144, brings the surface supplied with the pretreatment liquid into contact with the printing surface of the sheet 1, and applies the pretreatment liquid supplied to the surface to the printing surface of the sheet 1.

[0140] Note that the method of applying the pretreatment liquid to the printing surface of the sheet 1 is not limited to the method using the application roller 142, and for example, a method using a liquid ejection head may also be used.

[0141] The sheet 1 coated with the pretreatment liquid is conveyed to the pretreatment liquid drying unit 146. The pretreatment liquid drying unit 146 includes a hot air heater (not shown). The pretreatment liquid drying unit 146 blows hot air toward the printing surface of the sheet 1 from the hot air heater to dry the pretreatment liquid.

[0142] The sheet 1 with the dried pretreatment liquid is guided by the pass roller 122 and conveyed to the printing unit 150.

[0143] <Printing Unit> The printing unit 150 prints an image on the printing surface of the sheet 1. The printing unit 150 includes a printing drum 152, inkjet bars 14K, 14C, 14M, 14Y, 14W, ink supply devices 10K, 10C, 10M, 10Y, 10W, and a scanner 156.

[0144] The sheet 1 conveyed from the pretreatment liquid application unit 140 is guided by a plurality of pass rollers 122 and conveyed to the printing drum 152.

[0145] The printing drum 152 rotates by a motor (not shown), holds the sheet 1 on its outer peripheral surface, and conveys it. The printing drum 152 has a plurality of suction holes (not shown) on its outer peripheral surface. The printing drum 152 sucks the suction holes by a pump (not shown), thereby sucking the sheet 1 onto its outer peripheral surface.

[0146] The sheet 1 conveyed by the printing drum 152 is conveyed to a position facing the inkjet bars 14K, 14C, 14M, 14Y, 14W.

[0147] As the inkjet bars 14K, 14C, 14M, 14Y, 14W, the inkjet bars 14 shown in FIG. 1 can be respectively applied. The inkjet bars 14K, 14C, 14M, 14Y, 14W respectively eject aqueous inks of black (K), cyan (C), magenta (M), yellow (Y), and white (W). The aqueous ink refers to an ink in which coloring materials such as dyes and pigments are dissolved or dispersed in water and a solvent soluble in water. The aqueous white ink contains a titanium oxide material as a pigment, and the average particle diameter of the titanium oxide material (an example of the diameter of the dispersed particles) exceeds 100 nm. The average particle diameter is the particle diameter at the integrated value of 50% in the particle size distribution obtained by the laser diffraction / scattering method.

[0148] The inkjet bars 14K, 14C, 14M, 14Y, and 14W are each composed of line-type recording heads that can print on the paper 1 conveyed by the printing drum 152 by one scan. The inkjet bars 14K, 14C, 14M, 14Y, and 14W are each configured by connecting a plurality of head modules 15 in the X direction. The inkjet bars 14K, 14C, 14M, 14Y, and 14W are each arranged such that the nozzle surface faces the printing drum 152. The inkjet bars 14K, 14C, 14M, 14Y, and 14W are arranged at regular intervals along the conveyance path.

[0149] The ink supply devices 10K, 10C, 10M, 10Y, and 10W can each apply the ink supply device 10 shown in FIG. 1. The ink supply devices 10K, 10C, 10M, 10Y, and 10W each supply aqueous ink of the corresponding color to the inkjet bars 14K, 14C, 14M, 14Y, and 14W.

[0150] The scanner 156 includes an imaging device that images the image printed on the printing surface of the paper 1 and converts it into an electrical signal. A color CCD (Charge Coupled Device) linear image sensor can be used as the imaging device. Note that a color CMOS (Complementary Metal Oxide Semiconductor) linear image sensor can also be used instead of the color CCD linear image sensor.

[0151] In the printing unit 150, droplets of aqueous ink are ejected from at least one of the inkjet bars 14K, 14C, 14M, 14Y, and 14W toward the printing surface of the paper 1 conveyed by the printing drum 152. When the ejected droplets of aqueous ink adhere to the paper 1, an image is printed on the printing surface of the paper 1.

[0152] Also, the reading result is obtained by having the scanner 156 read the printing surface of the paper 1 conveyed by the printing drum 152.

[0153] <Drying section> The drying unit 170 dries the ink on the printing surface of the paper 1. The drying unit 170 includes a drying drum 172.

[0154] The paper 1 conveyed from the printing unit 150 is conveyed to the drying drum 172. The drying drum 172 is rotated by a motor (not shown), and holds and conveys the paper 1 on its outer peripheral surface. The drying drum 172 has a plurality of suction holes (not shown) on its outer peripheral surface. The drying drum 172 sucks the suction holes by a pump (not shown), thereby sucking the paper 1 onto its outer peripheral surface.

[0155] The drying unit 170 includes a hot air heater (not shown) around the drying drum 172. The drying unit 170 blows hot air toward the printing surface of the paper 1 from the hot air heater to dry the ink.

[0156] <Configuration of the head module> The inkjet bars 14K, 14C, 14M, 14Y, and 14W have a structure in which the head module 15 is joined in the X direction. FIG. 16 is a plan perspective view showing a structural example of the head module 15, and FIG. 17 is a cross-sectional view taken along line 17-17 of FIG. 16.

[0157] The head module 15 includes a nozzle plate 230 in which nozzles 202, which are ejection ports of ink droplets, are formed, and a flow path plate 232 in which ink flow paths are formed. The nozzle plate 230 and the flow path plate 232 are laminated and joined. The flow path plate 232 has a structure in which one or a plurality of substrates are laminated. The nozzle plate 230 and the flow path plate 232 can be processed into required shapes by a semiconductor manufacturing process using silicon as a material.

[0158] The head module 15 includes a plurality of nozzles 202 on a nozzle surface 200 which is a bottom surface. Further, a plurality of ink chamber units 206 including pressure chambers 204 and the like provided corresponding to each nozzle 202 are two-dimensionally arranged in a certain arrangement pattern. Thereby, a high density of the substantial nozzle pitch projected so as to be arranged along the X direction is achieved.

[0159] The pressure chamber 204 communicates with the supply branch 210 via the supply throttle 208, and each supply branch 210 communicates with the common flow path 212. Further, the descender 214 communicating with each pressure chamber 204 communicates with the circulation common flow path 220 via the ink circulation path 216 and the recovery branch 218. The head module 15 is provided with an ink supply port 15A and an ink discharge port 15B. The ink supply port 15A communicates with the common flow path 212, and the ink discharge port 15B communicates with the circulation common flow path 220.

[0160] Thus, the ink supply port 15A and the ink discharge port 15B of the head module 15 are configured to communicate with each other via the common flow path 212, the supply branch 210, the supply throttle 208, the pressure chamber 204, the descender 214, the ink circulation path 216, the recovery branch 218, and the circulation common flow path 220.

[0161] Therefore, the ink supplied to the ink supply port 15A flows through the common flow path 212, the supply branch 210, the supply throttle 208, the pressure chamber 204, and the descender 214. A part of the ink is ejected from each nozzle 202, and the remaining ink is discharged from the ink discharge port 15B via the ink circulation path 216, the recovery branch 218, and the circulation common flow path 220.

[0162] Note that the ink circulation path 216 is preferably provided around the nozzle 202. Here, the ink circulation path 216 is provided in a region that communicates with the descender 214 and that is in contact with the nozzle plate 230 of the flow path plate 232. Thereby, the ink circulates in the vicinity of the nozzle 202, so that the thickening of the ink inside the nozzle 202 is prevented and stable ejection becomes possible.

[0163] Further, a diaphragm 226 that forms the top surface of the pressure chamber 204 and also serves as a common electrode has an actuator 228 with individual electrodes (not shown) joined thereto. When a predetermined voltage is applied to the individual electrodes, the actuator 228 deforms in a direction to contract the pressure chamber 204. As a result, ink is ejected from the nozzle 202. Thereafter, the actuator 228 deforms in a direction to expand the pressure chamber 204. As a result, new ink is supplied to the pressure chamber 204 from the common flow path 212 through the supply branch 210 and the supply throttle 208.

[0164] Here, the actuator 228 is applied as a means for generating the ejection force of the ink ejected from the nozzle 202. However, it is also possible to apply a thermal method in which a heater is provided in the pressure chamber 204 and the ink is ejected by utilizing the pressure of film boiling caused by heating the heater.

[0165] The arrangement structure of the nozzles 202 is not limited to the illustrated example, and various nozzle arrangement structures such as an arrangement structure having a row of nozzles in the X direction can be applied.

[0166] 〔Control System of Inkjet Printing Apparatus〕 FIG. 18 is a block diagram showing the configuration of the control system of the inkjet printing apparatus 110. The inkjet printing apparatus 110 includes a conveyance control unit 250, a pretreatment liquid application control unit 252, a printing control unit 254, a drying control unit 256, a general control unit 258, and a user interface 264.

[0167] The conveyance control unit 250 rotates the take-up roll 182 by a motor (not shown) to unwind the paper 1 from the feed roll 132. The conveyance unit 120 guides the paper 1 by a plurality of pass rollers 122, and the take-up unit 180 winds the printed paper 1 around the take-up roll 182. As a result, the paper 1 is conveyed through the feed unit 130, the pretreatment liquid application unit 140, the printing unit 150, the drying unit 170, and the take-up unit 180.

[0168] The conveyance control unit 250 controls a pump (not shown) to adsorb the sheet 1 onto the outer peripheral surface of the printing drum 152. The conveyance control unit 250 rotates the printing drum 152 by a motor (not shown). Further, the conveyance control unit 250 acquires an encoder value from a rotary encoder (not shown) disposed on the printing drum 152.

[0169] The conveyance control unit 250 controls a pump (not shown) to adsorb the sheet 1 onto the outer peripheral surface of the drying drum 172. The conveyance control unit 250 rotates the drying drum 172 by a motor (not shown).

[0170] The pretreatment liquid application control unit 252 causes the application roller 142 to apply the pretreatment liquid to the printing surface of the sheet 1. Further, the pretreatment liquid application control unit 252 dries the pretreatment liquid applied to the printing surface of the sheet 1 by a hot air heater (not shown) of the pretreatment liquid drying unit 146.

[0171] The printing control unit 254 includes a valve control unit 97 and a pump control unit 98, and comprehensively controls the operation of the ink supply device 10.

[0172] The printing control unit 254 controls the ejection of ink by the inkjet bars 14K, 14C, 14M, 14Y, and 14W based on the print data. The printing control unit 254 ejects ink droplets of cyan, cyan, magenta, yellow, and white, respectively, toward the sheet 1 by the inkjet bars 14K, 14C, 14M, 14Y, and 14W in synchronization with the encoder value acquired via the conveyance control unit 250. Thereby, a color image is printed on the printing surface of the sheet 1, and the sheet 1 becomes a "printed matter".

[0173] Note that the overall control unit 258 normally operates the ink supply device 10 during printing when an image is printed on the sheet 1 by the inkjet bars 14K, 14C, 14M, 14Y, and 14W, and performs maintenance operations during non-printing times other than during printing.

[0174] In addition, it is desirable that the overall control unit 258 perform the stirring sequences of the ink supply devices 10K, 10C, 10M, 10Y, and 10W during the startup process when the inkjet printing apparatus 110 is activated. Further, it is desirable that the overall control unit 258 perform the stirring sequences of the ink supply devices 10K, 10C, 10M, 10Y, and 10W periodically, for example, every three hours, after the power of the inkjet printing apparatus 110 is turned off.

[0175] Here, the ink supply device 10 is applied to each of the aqueous inks of black, cyan, magenta, yellow, and white. However, it is particularly important to apply the ink supply device 10 to the aqueous white ink. The aqueous white ink contains a titanium oxide material with an average particle diameter exceeding 100 nm, and the titanium oxide material tends to settle. Therefore, by applying the ink supply device 10 to the aqueous white ink, the contaminated aqueous white ink does not adversely affect the ejection, and sedimentation can be effectively prevented.

[0176] In addition, the printing control unit 254 causes the scanner 156 to read the image printed on the paper 1 in synchronization with the encoder value acquired via the conveyance control unit 250, and acquires the reading result.

[0177] The inkjet printing apparatus 110 may form a detection pattern by the printing control unit 254 and analyze the reading result read by the scanner 156 to acquire information on the location of the nozzles 202 with ejection defects. Note that the printing control unit 254 may output the information on the location of the nozzles 202 with ejection defects to the overall control unit 258.

[0178] In addition, the printing control unit 254 may have a compensation function for correcting the printing data and compensating the printing area of the nozzles 202 with ejection defects. As an example, there is a compensation function for compensating by increasing the volume of ink droplets of a plurality of adjacent nozzles 202 with respect to the nozzles 202 with ejection defects. The printing control unit 254 outputs information on the locations compensated by the compensation function of the printed matter to the overall control unit 258.

[0179] The drying control unit 256 controls the heating by a hot air heater (not shown) to dry the sheet 1 by the drying unit 170.

[0180] The overall control unit 258 comprehensively controls the operation of the inkjet printing apparatus 110 by controlling the conveyance control unit 250, the pretreatment liquid application control unit 252, the printing control unit 254, and the drying control unit 256, respectively. The overall control unit 258 includes a processor 260 and a memory 262. The overall control unit 258 includes the overall control unit 94 (see FIG. 2). The processor 260 may be the processor 95. The memory 262 may be the memory 96.

[0181] The user interface 264 includes an input unit (not shown) for the user to operate the inkjet printing apparatus 110 and a display unit (not shown) for presenting information to the user. The input unit is, for example, an operation panel that receives an input from the user. The display unit is, for example, a display that displays image data and various types of information. The user can use the user interface 264 to cause the inkjet printing apparatus 110 to print a desired image.

[0182] Here, although an example in which the ink supply apparatuses 10K, 10C, 10M, 10Y, and 10W each apply the ink supply apparatus 10 has been described, when the inkjet bars 14K, 14C, 14M, 14Y, and 14W have an ink flow path configuration in which the ink does not circulate up to the head module 15, the ink supply apparatuses 100 may be applied as the ink supply apparatuses 10K, 10C, 10M, 10Y, and 10W, respectively.

[0183] 〔Others〕 The technical scope of the present invention is not limited to the scope described in the above embodiments. The configurations and the like in each embodiment can be appropriately combined among the embodiments without departing from the gist of the present invention.

Explanation of Reference Numerals

[0184] 1... Sheet 10, 10C, 10K, 10M, 10W, 10Y… Ink supply device 12… Buffer tank 14, 14C, 14K, 14M, 14W, 14Y… Inkjet bar 15(15-1~15-n)… Head module 15A… Ink supply port 15B… Ink discharge port 16… Supply flow path 18… Recovery flow path 20… Circulation flow path 22… Degassing module 24… Supply pump 26… Supply side filter 28… Heat exchanger 30… Supply side back pressure tank 30A… Ink inlet 30B… Ink outlet 30C… Liquid chamber 30D… Gas chamber 30E… Elastic membrane 30F… Bubble discharge port 30G… Air flow path communication port 32… Supply side head manifold 34… Supply side pressure sensor 36… Supply valve 36(36-1~36-n)… Supply valve 38(38-1~38-n)… Supply damper 40(40-1~40-n)… Recovery damper 42(42-1~42-n)… Recovery valve 44… Recovery side head manifold 46… Recovery side pressure sensor 48… Recovery side back pressure tank 48A… Ink inlet 48B… Ink outlet 48C… Liquid chamber 48D… Gas chamber 48E… Elastic membrane 48F… Bubble discharge port 48G… Air flow path communication port 50… Recovery pump 52… Recovery flow path valve 54… Drain flow path 56… Drain valve 58… Air flow path 59… Air connection valve 60… Air tank 61… Atmosphere connection path 62… Air valve 64… First bypass flow path 66… Second bypass flow path 68… First bypass flow path valve 69… Second bypass flow path valve 70… Drain valve 71… Air flow path 72… Air connection valve 73… Air tank 74… Atmosphere connection path 75… Air valve 76… Ink main tank 76A… Filter for main tank 78… Supply flow path 80… Overflow flow path 82… Supply pump 84… First safety valve 86… Second safety valve 88… Third safety valve 90… Recovery side filter 92… Recovery side filter valve 94… Overall control unit 95… Processor 96… Memory 97… Valve control unit 98… Pump control unit 99A… Stirring flow path 99B… Stirring flow path 99C… Stirring flow path 99D… Stirring flow path 102… Inkjet bar 110… Inkjet printing device 120… Conveyor unit 122… Pass roller 130… Delivery section 132… Delivery roll 140… Pretreatment liquid application section 142… Application roller 144… Opposing roller 146…Pretreatment liquid drying section 150…Printing section 152…Printing drum 156…Scanner 170…Drying section 172…Drying drum 180…Rewinding section 182…Rewinding roll 200…Nozzle surface 202…Nozzle 204…Pressure chamber 206…Ink chamber unit 210…Supply branch 212…Common flow path 214…Descender 216…Ink circulation path 218…Recovery branch 220…Circulation common flow path 226…Diaphragm 228…Actuator 230…Nozzle plate 232…Flow path plate 250…Conveyor control unit 252…Pretreatment liquid application control unit 254…Printing control unit 256…Drying control unit 258…Overall control unit 260…Processor 262…Memory 264…User interface F…Joint S1~S5…Each step of the control method of the ink supply device

Claims

1. A circulation flow path that supplies the liquid from a liquid tank that stores the liquid to a liquid discharge head and recovers the liquid from the liquid discharge head to the liquid tank, A pump provided in the circulation flow path that generates a flow in the liquid in the circulation flow path, A memory that stores instructions for execution by a processor, A processor that executes the instructions stored in the memory, Comprising: The processor: Performs a sequence including a first process of generating a forward flow in the first direction in the liquid in a first flow path including at least a part of the circulation flow path by controlling the pump, and a second process of generating a reverse flow in the direction opposite to the first direction in the liquid in the first flow path, In the first flow path, a filter for removing foreign matter in the liquid is disposed between the liquid tank in the forward flow and the liquid discharge head, The flow rate of the liquid in the forward flow is greater than the flow rate of the liquid in the reverse flow, The reverse flow has a steady flow state, In the first flow path, no filter for removing foreign matter in the liquid is disposed between the liquid tank in the reverse flow and the liquid discharge head, A liquid supply device.

2. A circulation flow path that supplies the liquid from a liquid tank that stores the liquid to a liquid discharge head and recovers the liquid from the liquid discharge head to the liquid tank, A pump provided in the circulation flow path that generates a flow in the liquid in the circulation flow path, A memory that stores instructions for execution by a processor, A processor that executes the instructions stored in the memory, Comprising: The processor: Performs a sequence including a first process of generating a forward flow in the first direction in the liquid in a first flow path including at least a part of the circulation flow path by controlling the pump, and a second process of generating a reverse flow in the direction opposite to the first direction in the liquid in the first flow path, In the first flow path, a filter for removing foreign matter in the liquid is disposed between the liquid tank in the forward flow and the liquid discharge head, The flow rate of the liquid in the forward flow is greater than the flow rate of the liquid in the reverse flow, The reverse flow has a steady flow state, The processor performs the sequence a plurality of times. A liquid supply device.

3. A circulation flow path that supplies the liquid from a liquid tank that stores the liquid to a liquid discharge head and recovers the liquid from the liquid discharge head to the liquid tank, A pump provided in the circulation flow path for generating a flow in the liquid in the circulation flow path, A memory for storing instructions for execution by a processor, A processor for executing the instructions stored in the memory, Comprising, The processor, By controlling the pump, a first process of generating a positive flow in the first direction in the liquid in a first flow path including at least a part of the circulation flow path, and a second process of generating a negative flow in a direction opposite to the first direction in the liquid in the first flow path, and implementing a sequence including these, In the first flow path, a filter for removing foreign matter in the liquid is disposed between the liquid tank of the positive flow and the liquid discharge head, The flow rate of the liquid of the positive flow is larger than the flow rate of the liquid of the negative flow, The negative flow has a steady flow state, The first flow path includes a second flow path different from the circulation flow path, The flow rate of the liquid of the negative flow is smaller than the volume of the second flow path, Liquid supply device.

4. A circulation flow path for supplying the liquid from a liquid tank storing the liquid to a liquid discharge head and recovering the liquid from the liquid discharge head to the liquid tank, A pump provided in the circulation flow path for generating a flow in the liquid in the circulation flow path, A memory for storing instructions for execution by a processor, A processor for executing the instructions stored in the memory, Comprising, The processor, By controlling the pump, a first process of generating a positive flow in the first direction in the liquid in a first flow path including at least a part of the circulation flow path, and a second process of generating a negative flow in a direction opposite to the first direction in the liquid in the first flow path, and implementing a sequence including these, In the first flow path, a filter for removing foreign matter in the liquid is disposed between the liquid tank of the positive flow and the liquid discharge head, The flow rate of the liquid of the positive flow is larger than the flow rate of the liquid of the negative flow, The negative flow has a steady flow state, The first flow path includes a second flow path different from the circulation flow path, Before implementing the sequence, the processor controls the pump to replace the liquid in the second flow path with the liquid from which the foreign matter has been removed by the filter, Liquid supply device.

5. A circulation flow path for supplying the liquid from a liquid tank storing the liquid to a liquid discharge head and recovering the liquid from the liquid discharge head to the liquid tank, A pump provided in the circulation flow path for generating a flow in the liquid in the circulation flow path; A memory storing instructions for causing a processor to execute; A processor for executing the instructions stored in the memory; Comprising; The processor; By controlling the pump, a first process of generating a positive flow in the first direction in the liquid in the first flow path including at least a part of the circulation flow path, and a second process of generating a negative flow in the direction opposite to the first direction in the liquid in the first flow path, and implementing a sequence including; In the first flow path, a filter for removing foreign matter in the liquid is disposed between the liquid tank of the positive flow and the liquid discharge head; The flow rate of the liquid of the positive flow is larger than the flow rate of the liquid of the negative flow; The negative flow has a steady flow state; The first flow path includes a second flow path different from the circulation flow path; After implementing the sequence, the processor controls the pump to replace the liquid in all the flow paths through which the liquid of the negative flow has flowed in the first flow path with the liquid from which the foreign matter has been removed by the filter; A liquid supply device. [

6. ] A liquid tank for storing liquid; A liquid discharge head for discharging the liquid from a discharge port; A moving mechanism for relatively moving the liquid discharge head and the printing substrate; The liquid supply device according to any one of claims 1 to 5; Comprising; The processor; While relatively moving the liquid discharge head and the printing substrate, discharging the liquid from the discharge port of the liquid discharge head to print an image on the printing substrate; During printing, circulating the liquid in the circulation flow path; During non-printing times other than during printing, implementing the sequence; A printing device. [

7. ] The volume velocity of the positive flow is at least temporarily larger than the volume velocity during printing; The printing device according to claim 6. [

8. ] The volume velocity of the negative flow is at least temporarily larger than the volume velocity during printing; The printing device according to claim 6 or 7. [

9. ] The liquid has particles with a diameter exceeding 100 nm dispersed therein; The printing device according to any one of claims 6 to 8. [

10. ] The liquid is white ink containing a titanium oxide material; The printing device according to any one of claims 6 to 9. [

11. ] The circulation flow path includes a valve for opening and closing a part of the flow paths in the circulation flow path; The processor controls the valve to determine the first flow path. The printing apparatus according to any one of claims 6 to 10.

12. A control method for a liquid supply device including a circulation flow path that supplies the liquid from a liquid tank storing the liquid to a liquid discharge head and recovers the liquid from the liquid discharge head to the liquid tank, and a pump provided in the circulation flow path that generates a flow in the liquid in the circulation flow path, the method comprising: Performing a sequence including a first process of generating a positive flow in a first direction in the liquid in a first flow path including at least a part of the circulation flow path by controlling the pump, and a second process of generating a negative flow in a direction opposite to the first direction in the liquid in the first flow path; In the first flow path, a filter for removing foreign matter in the liquid is disposed between the liquid tank and the liquid discharge head in the positive flow. The flow rate of the liquid in the positive flow is larger than the flow rate of the liquid in the negative flow. The negative flow has a steady flow state. In the first flow path, no filter for removing foreign matter in the liquid is disposed between the liquid tank and the liquid discharge head in the negative flow. A control method for a liquid supply device.

13. A control method for a liquid supply device including a circulation flow path that supplies the liquid from a liquid tank storing the liquid to a liquid discharge head and recovers the liquid from the liquid discharge head to the liquid tank, and a pump provided in the circulation flow path that generates a flow in the liquid in the circulation flow path, the method comprising: Performing a sequence including a first process of generating a positive flow in a first direction in the liquid in a first flow path including at least a part of the circulation flow path by controlling the pump, and a second process of generating a negative flow in a direction opposite to the first direction in the liquid in the first flow path; In the first flow path, a filter for removing foreign matter in the liquid is disposed between the liquid tank and the liquid discharge head in the positive flow. The flow rate of the liquid in the positive flow is larger than the flow rate of the liquid in the negative flow. The negative flow has a steady flow state. Performing the sequence a plurality of times. A control method for a liquid supply device.

14. A control method for a liquid supply device, comprising a circulation flow path that supplies the liquid from a liquid tank storing the liquid to a liquid discharge head and recovers the liquid from the liquid discharge head to the liquid tank, and a pump provided in the circulation flow path that generates a flow in the liquid in the circulation flow path. By controlling the pump, a first process of generating a positive flow in the first direction in the liquid in a first flow path including at least a part of the circulation flow path, and a second process of generating a negative flow in the direction opposite to the first direction in the liquid in the first flow path are included in a sequence to be implemented. In the first flow path, a filter for removing foreign matter in the liquid is disposed between the liquid tank and the liquid discharge head in the positive flow. The flow rate of the liquid in the positive flow is greater than the flow rate of the liquid in the negative flow. The negative flow has a steady flow state. The first flow path includes a second flow path different from the circulation flow path. The flow rate of the liquid in the negative flow is smaller than the volume of the second flow path. A control method for a liquid supply device.

15. A control method for a liquid supply device, comprising a circulation flow path that supplies the liquid from a liquid tank storing the liquid to a liquid discharge head and recovers the liquid from the liquid discharge head to the liquid tank, and a pump provided in the circulation flow path that generates a flow in the liquid in the circulation flow path. By controlling the pump, a first process of generating a positive flow in the first direction in the liquid in a first flow path including at least a part of the circulation flow path, and a second process of generating a negative flow in the direction opposite to the first direction in the liquid in the first flow path are included in a sequence to be implemented. In the first flow path, a filter for removing foreign matter in the liquid is disposed between the liquid tank and the liquid discharge head in the positive flow. The flow rate of the liquid in the positive flow is greater than the flow rate of the liquid in the negative flow. The negative flow has a steady flow state. The first flow path includes a second flow path different from the circulation flow path. Before implementing the sequence, by controlling the pump, the liquid in the second flow path is replaced with the liquid from which the foreign matter has been removed by the filter. A control method for a liquid supply device.

16. A control method for a liquid supply device comprising a circulation flow path that supplies the liquid from a liquid tank storing the liquid to a liquid discharge head and recovers the liquid from the liquid discharge head to the liquid tank, and a pump provided in the circulation flow path that generates a flow in the liquid in the circulation flow path. By controlling the pump, a sequence is performed that includes a first process of generating a positive flow in the first direction in the liquid in a first flow path including at least a part of the circulation flow path, and a second process of generating a negative flow in the opposite direction to the first direction in the liquid in the first flow path. In the first flow path, a filter for removing foreign matter in the liquid is disposed between the liquid tank and the liquid discharge head in the positive flow. The flow rate of the liquid in the positive flow is greater than the flow rate of the liquid in the negative flow. The negative flow has a steady flow state. The first flow path includes a second flow path different from the circulation flow path. After performing the sequence, by controlling the pump, the liquid in all the flow paths through which the liquid in the negative flow has flowed in the first flow path is replaced with the liquid from which the foreign matter has been removed by the filter. A control method for a liquid supply device.

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