Inkjet recording device

Abstract

With respect to an inkjet recording device in which a pigment-based ink is used, provided is an ink device that can suppress ink adherence in an ink path and precipitation of pigment components in an ink container, which occur when printing is not implemented for a long period of time, and can jet the pigment-based ink in a short period of time when printing is resumed. In this inkjet recording device in which a pigment-based ink is used, a control unit 7 executes a printing mode in which a printing operation is implemented, and a suspension mode in which a printing operation is not implemented. In the suspension mode, the control unit 7 forcibly causes stirring of a pigment-based ink 68A in an ink container 31, and ink circulation (S300) in an ink circulation path that does not include a printing head, or ink circulation (S400) in an ink circulation path that includes the printing head. Thereby, ink adherence in the ink circulation path and precipitation of pigment components in the ink container, which occur when printing is not implemented for a long period of time, can be suppressed, and the pigment-based ink can be jetted in a short period of time when printing is resumed.

Description

[Technical Field]

[0001] The present invention relates to an inkjet recording apparatus, and more particularly to an inkjet recording apparatus that uses pigment-based ink. [Background technology]

[0002] A typical continuous-jet, charge-controlled inkjet recording device has an ink container that stores ink in the main body, and the ink from that container is supplied to the print head by an ink supply pump. The ink supplied to the print head is continuously ejected from the ink nozzles and turned into ink droplets. Of the ink droplets used for printing, those that are charged and deflected are then propelled to the desired printing position on the print target to form characters, while ink droplets that are not used for printing are not charged or deflected, but are collected in a gutter and returned to the ink container by an ink recovery pump.

[0003] Such an inkjet recording device is shown in, for example, Japanese Patent Application Laid-Open No. 2021-14040 (Patent Document 1).

[0004] Patent Document 1 shows an inkjet recording device that has a print head that receives a supply of ink and performs printing, and a main body that includes an ink container for storing ink and a solvent container for storing solvent, and supplies the ink in the ink container to the print head, the print head having nozzles that convert the ink into ink particles and eject them, charging electrodes that charge the ink particles ejected from the nozzles in accordance with the print content, deflection electrodes that change the flight direction of the charged ink particles, and a gutter that collects ink particles that do not contribute to printing.

[0005] Furthermore, this inkjet recording device is equipped with a head cleaning unit including a cleaning tank for setting the print head, a cleaning nozzle that sprays solvent toward the print head set in the cleaning tank to clean it, and a recovery container located at the bottom of the cleaning tank for recovering the solvent after cleaning, and a drive unit that supplies solvent to the cleaning nozzle.

[0006] Further, as another inkjet recording apparatus, for example, the one described in Japanese Patent Laid-Open No. 2019-98658 (Patent Document 2) is known.

[0007] Patent Document 2 shows an inkjet recording device that includes an ink container that can store pigment-based ink for printing on a print target, a nozzle connected to the ink container and that ejects the ink, a charging electrode that charges the ink that is ejected from the nozzle and used for printing, a deflection electrode that deflects the ink charged by the charging electrode, a stirring mechanism that stirs the ink stored in the ink container, a stirring detection sensor provided in the ink container, and a control unit that determines whether the stirring detection sensor is conductive.

[0008] Furthermore, it is shown that the stirring detection sensor has two electrodes, the first electrode having a length that allows it to be immersed in the ink in the ink container, and the second electrode being fixed when the stirring mechanism is operating, and the contact state between the first electrode and the second electrode changes depending on whether the stirring mechanism is stirring the ink or not stirring the ink. [Prior art documents] [Patent documents]

[0009] [Patent Document 1] Patent Publication No. 2021-14040 [Patent Document 2] Japanese Patent Application Publication No. 2019-98658 Summary of the Invention [Problem to be solved by the invention]

[0010] The above-mentioned Patent Document 1 describes an inkjet recording device and control that can prevent ink from solidifying in the path by periodically circulating ink when the print head is set in a head cleaning unit. However, Patent Document 1 targets dye ink and does not take into consideration pigment ink.

[0011] In other words, in an inkjet recording device that uses pigment-based ink, if the pigment-based ink is left without being stirred for a certain period of time, the pigment components contained in the pigment-based ink may settle to the bottom of the ink container, interfering with the normal operation of the stirring bar provided in the ink container. If this condition is left unnoticed, the pigment-based ink may not be stirred, which may interfere with the normal supply of pigment-based ink.

[0012] Furthermore, in Patent Document 2, while the pigment-based ink used for printing is being ejected, the stirring bar of the stirring mechanism inside the ink container is rotated to stir the pigment components while stirring them, preventing the pigment components in the pigment-based ink from settling inside the ink container, and the stirring state is detected by a stirring detection sensor.

[0013] However, since the stirring mechanism operates only while ink is being ejected during printing, if the inkjet recording device is left unused for a long period of time, the pigment-based ink may solidify in the ink path or the pigment components of the pigment-based ink may precipitate in the ink container, making it impossible to supply the pigment-based ink when printing is resumed, which may result in printing becoming impossible.

[0014] An object of the present invention is to provide an inkjet recording device that uses pigment-based ink, which can suppress ink adhesion in the ink path and pigment component precipitation in the ink container that occur when printing is not performed for a long period of time, and can eject pigment-based ink in a short time when printing is resumed. [Means for solving the problem]

[0015] The present invention provides a print head having a nozzle for atomizing and ejecting supplied pigment-based ink, a charging electrode for charging the ink particles ejected from the nozzle, a deflection electrode for deflecting the ink particles charged by the charging electrode, a gutter for recovering unused ink not used in printing, an ink container for storing the pigment-based ink and having a stirring mechanism for stirring the stored pigment-based ink, a first ink circulation path including the print head for supplying the pigment-based ink in the ink container to the print head and recovering the pigment-based ink into the ink container while circulating it, and The ink jet recording device is characterized in that it is equipped with a second ink circulation path that does not include a print head, which does not supply the pigment-based ink to the print head, but instead circulates the pigment-based ink while collecting it in an ink container, and a control unit that controls the operation of the print head and the stirring mechanism, and the control unit executes a print mode in which a printing operation is performed and a pause mode in which a printing operation is not performed, and in the pause mode, it stirs the pigment-based ink in the ink container and circulates the ink in the first ink circulation path that includes the print head, or circulates the ink in the second ink circulation path that does not include a print head. [Effects of the Invention]

[0016] According to the present invention, in an inkjet recording device that uses pigment-based ink, when printing is not being performed, the ink container is stirred and the ink is circulated in the ink circulation path forcibly, thereby suppressing ink adhesion in the ink circulation path and precipitation of pigment components in the ink container, which occur when printing is not performed for a long period of time, and achieving the effect of enabling the pigment-based ink to be ejected in a short time when printing is resumed. [Brief explanation of the drawings]

[0017] [Figure 1] 1 is a diagram illustrating a usage situation of an inkjet printing apparatus according to an embodiment of the present invention. [Figure 2] FIG. 2 is a diagram showing a path configuration of an inkjet recording apparatus according to the present embodiment. [Figure 3] FIG. 2 is a diagram illustrating the configuration of a control unit of the inkjet recording apparatus according to the present embodiment. [Figure 4]FIG. 2 is a vertical cross-sectional view showing the configuration of an ink container according to the present embodiment. [Figure 5] FIG. 4 is a vertical cross-sectional view showing an operating state of the stirrer of the ink container according to the embodiment. [Figure 6A] FIG. 10 is a flowchart showing a control flow for switching between a pause mode and a print mode in the present embodiment. [Figure 6B] FIG. 10 is a flowchart showing a detailed control flow of a sleep mode in this embodiment. [Figure 6C] FIG. 6C is a flowchart showing the detailed control flow of step S100 in FIG. 6B. [Figure 6D] FIG. 6C is a flowchart showing the detailed control flow of step S200 in FIG. 6B. [Figure 6E] FIG. 6C is a flowchart showing the detailed control flow of step S300 in FIG. 6B. [Figure 6F] FIG. 6C is a flowchart showing the detailed control flow of step S400 in FIG. 6B. [Figure 7] 3A and 3B are explanatory diagrams illustrating ink paths and the flow of ink and air when ink is circulating in the print head in this embodiment. [Figure 8] 5A and 5B are explanatory diagrams illustrating the flow of ink and air when ink is circulating in an ink path in the present embodiment. [Figure 9] 5A and 5B are explanatory diagrams illustrating the ink paths and the display screen when ink is circulating in the print head in the embodiment. [Figure 10] FIG. 10 is an explanatory diagram illustrating a display screen when ink is circulating in the ink path in the embodiment. [Figure 11] 10 is an explanatory diagram illustrating a selection screen for enabling / disabling periodic ink circulation processing in the present embodiment. FIG. DETAILED DESCRIPTION OF THE INVENTION

[0018] Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. However, the present invention is not limited to the following embodiments, and various modifications and application examples within the technical concept of the present invention are also included within its scope. The present invention is not limited to the embodiments described below. Furthermore, in the following drawings, the same devices are given the same numbers (symbols), and descriptions of components that have already been described may be omitted.

[0019] [Explanation of the overall configuration of the inkjet recording device] First, the usage state of an inkjet recording apparatus according to an embodiment of the present invention will be described with reference to Fig. 1. Fig. 1 shows the usage state of an inkjet recording apparatus according to an embodiment of the present invention.

[0020] In Figure 1, inkjet recording device 600A and inkjet recording device 600B installed in a manufacturing factory each include a main body 1, a print head 2 connected to main body 1 by a cable (for print head) 5, and a head mounting unit 3 connected to main body 1 by a cable (for head mounting unit) 6.

[0021] Here, the head mounting unit 3 basically has the function of housing the print head 2, but it may also have the added function of spraying cleaning fluid to clean the print head. The head mounting unit 3 described below has a configuration that adds the function of cleaning the print head.

[0022] Inkjet recording device 600A shows the print head 2 installed on the production line. Inkjet recording device 600B shows the print head 2 removed from the production line and attached (set) to the head mounting unit 3. The collection container 4 attached to the bottom of the head mounting unit 3 is provided to contain the liquid (cleaning liquid) used to clean the print head using the head mounting unit 3.

[0023] Inkjet recording device 600A is installed on a production line in a factory where food, beverages, etc. are produced, and main body 1 is installed in a location where there is enough space for regular maintenance work, etc. Print head 2 is fixed to print head fixing bracket 13 installed near belt conveyor 11, and is installed in close proximity to print objects 12A and 12B fed in the direction of arrow X on the production line such as belt conveyor 11.

[0024] In addition, a protective cover 17 is attached to the print head 2 in order to protect the components inside the print head 2. The print target 12B is shown in a state where printing by the print head 2 has been completed and the object is being transported on the belt conveyor 11.

[0025] 1, main body 1 contains (holds) ink for printing, and controls a drive unit (pump and solenoid valve) inside the main body to supply ink to print head 2 via cable (for print head) 5. The internal path configuration of main body 1 and details of the control unit will be described later.

[0026] The operation and display unit 8 is installed on the top surface of the main body 1 and uses a touch input display panel in this case. By touching the operation and display unit 8, the operator can instruct the control unit to start or stop the device and set the content to be printed on the printing target 12A. Also in Figure 1, the print head 2 is equipped with a head base 16 and a protective cover 17.

[0027] The head mounting unit 3 is installed around the print head 2. The head mounting unit 3 in the inkjet recording device 600A is fixed by combining a fixing jig 92 attached to the belt conveyor 11 with a mating part 93 attached to the head mounting unit 3.

[0028] The head mounting unit 3 has a head mounting section 81A for mounting the print head 2 to the head mounting unit. The head mounting unit 3 also has a start button 18 for starting the cleaning process of the print head 2, a stop button 19 for stopping the cleaning process of the print head 2, and a display section 20 for displaying confirmation messages and alarms such as warnings and abnormalities to the operator.

[0029] The display unit 20 may be configured to allow the operator to recognize the operating state and the presence or absence of an abnormality, for example, by the presence or absence of a light or by different colors.

[0030] In the inkjet recording device 600A of this embodiment, the head mounting unit 3 is fixed near the belt conveyor 11, but the head mounting unit 3 can be freely relocated to a location that is easier for the user to operate. The length of the cable (for the head mounting unit) 6 that connects the main body 1 and the head mounting unit 3 is preferably the same as or longer than the cable 5 that connects the main body 1 and the print head 2 of the inkjet recording device 600. This is to ensure a degree of freedom in the placement of the head mounting unit.

[0031] In addition, the main body 1 has a fixing portion 91 for fixing the head mounting unit 3, and the head mounting unit 3 can be used by removing the head mounting unit from the fixing jig (for conveyor) 92 and replacing it with the fixing portion 91.

[0032] When the inkjet recording device 600B is in use, the head mounting unit 3 can be fixed to the main body 1 by combining a mating part 93 with a fixing part 91 assembled to the main body 1. The head mounting unit 3 of the inkjet recording device 600B is attached to the main body 1. By making it possible to fix the head mounting unit 3 to the main body 1, it becomes possible to install the head mounting unit 3 even when there is no space to install the head mounting unit 3 near the belt conveyor 11, for example.

[0033] Next, we will explain the state in which the print head 2 is set in the head mounting unit 3 of the inkjet recording device 600B. The print head 2 is set by attaching the tip of the print head 2 to the head mounting section 81A of the head mounting unit 3. By setting the print head 2 in the head mounting unit in this way, the inkjet recording device 600 of this embodiment can clean the print head 2 with solvent 69A supplied from the main body 1 via the cable (for the head mounting unit) 6.

[0034] [Explanation of ink circulation path] Next, the configuration of the ink circulation path in the inkjet recording apparatus 600 in this embodiment will be described with reference to Fig. 2. Note that, hereinafter, the ink circulation path may be referred to as the ink path, and in this case, it will be read as the ink circulation path.

[0035] Furthermore, even when a path through which ink flows is given a separate name, it is treated as constituting part of the ink circulation path. In short, the path through which ink flows is categorized as the ink circulation path.

[0036] 2 shows the overall configuration of the ink paths of the inkjet recording apparatus 600 of this embodiment. First, the ink paths (paths 801 to 804) of the inkjet recording apparatus 600 of this embodiment will be described.

[0037] 2, the main body 1 is provided with a main ink container 31 that stores circulating pigment-based ink 68A, and an auxiliary ink container 32 that stores pigment-based ink 68C. Here, the auxiliary ink container 32 has the same configuration as the main ink container 31, so a description of the stirring of the pigment-based ink 68C will be omitted.

[0038] As shown in Figures 4 and 5, a stirrer 101 and a motor 102 for operating the stirrer 101 are installed at the bottom of the main ink container 31. Also housed inside the main ink container 31 is a stirrer 103 that rotates in conjunction with a rotor 104 of the stirrer 101. The rotation of the stirrer 103 prevents the pigment components of the pigment-based ink 68A in the main ink container 31 from settling to the bottom of the main ink container 31. The operation of the stirrer 101 and the stirrer 103 will be explained in more detail with reference to Figures 4 and 5.

[0039] A temperature sensor 38 is attached to the main body 1 and is connected to the control unit 7 installed in the main body 1. The main ink container 31 is also provided with a liquid level sensor 31A that detects whether the liquid (pigment-based ink 68A) in the main ink container 31 has reached a reference liquid level, which is the appropriate amount to be held inside.

[0040] The main ink container 31 is connected to an ink path (supply) 801 at the portion immersed in the pigment-based ink 68A, and an electromagnetic valve (supply) 49 that opens and closes the ink path 801 is installed in the middle of the ink path 801.

[0041] Furthermore, ink path 801 is connected via a junction path 901 to a pump (for supply) 34 that is installed in ink path 802 and is used to suck and pressure-feed pigment-based ink 68A. The output side of pump (for supply) 34 is connected to a filter (for supply) 39 that removes foreign matter mixed in the pigment-based ink 68A.

[0042] The filter (supply) 39 is connected to a pressure regulating valve 46 that adjusts the pressure of the pigment-based ink 68A pumped from the pump (supply) 34 to an appropriate pressure for printing, and the pressure regulating valve 46 is connected to a pressure sensor 47 that measures the pressure of the pigment-based ink 68A supplied to the nozzle 21.

[0043] The ink path 802 in which the pressure sensor 47 is arranged is connected to an ink path 803 that passes through the cable (for print head) 5 via a branch path 921, and the ink path 803 is connected to a switching valve 26 provided in the print head 2 for controlling whether or not pigment-based ink 68A is supplied to the nozzle 21.

[0044] The switching valve 26 is connected to a nozzle 21 having an ejection port 21A that ejects the pigment-based ink 68A via an ink path 804. The switching valve 26 is a three-way electromagnetic valve, and an ink path 802 for ink supply and an ink path 835 for nozzle cleaning are connected to the switching valve 26, so that the supply of the pigment-based ink 68A and the solvent 69A to the nozzle 21 can be switched.

[0045] In the straight direction of the ejection port 21A of the nozzle 21, there are arranged a charging electrode 23 for adding a predetermined amount of charge to the ink particles 68B, a deflection electrode 24 for deflecting the ink particles 68B to be used for printing, and a gutter 25 for capturing ink particles that are not used for printing and therefore are not charged or deflected and fly straight.

[0046] Next, the ink recovery paths 811 and 812 of the inkjet recording apparatus 600 will be described.

[0047] 2, the gutter 25 is connected to an ink path 811, and a charge sensor (autophase sensor) 48 is disposed in the ink path 811 to detect whether ink particles to which an electric charge has been added by the charging electrode 23 are being collected. The ink path 811 passes through a cable (for the print head) 5 and is connected to a filter (for collection) 40 disposed in the main body 1 that removes foreign matter mixed in with the ink, and the filter (for collection) 40 is connected to a solenoid valve (for collection) 50 that opens and closes the ink path.

[0048] The solenoid valve (for recovery) 50 is disposed in the ink path 812 connected via the confluence path 902, and is connected to the pump (for recovery) 35 that sucks up the ink particles captured by the gutter 25. The pump (for recovery) 35 is connected to the main ink container 31. By opening the solenoid valve 50 and driving the pump 35, the ink particles captured by the gutter 25 are collected into the ink container 31.

[0049] Next, the exhaust path 814 of the inkjet recording apparatus 600 in this embodiment will be described.

[0050] The ink container 31 is connected to an exhaust path 814 in the upper space that does not come into contact with the pigment-based ink 68A, and the exhaust path 814 is connected to an exhaust duct connection part 62 that communicates with the outside of the main body 1.

[0051] Next, the ink paths (paths 821 and 822) of the inkjet recording apparatus 600 in this embodiment will be described.

[0052] The nozzles 21 provided in the print head 2 are connected to an ink path 804 for supplying ink, as well as to an ink path 821 that passes through the cable (for print head) 5. This ink path 821 is provided with a solenoid valve (for circulation) 59 provided in the main body 1 that opens and closes the flow path.

[0053] The solenoid valve (for circulation) 59 is connected to the ink path 822 via a junction path 903, and the ink path 822 is provided with a pump (for circulation) 36 that sucks ink from the nozzles 21. The pump (for circulation) 36 is connected to the main ink container 31.

[0054] Next, the viscosity measurement paths (824 and 822) of the inkjet recording apparatus 600 in this embodiment will be described.

[0055] 2, the portion of the main ink container 31 that is immersed in the pigment-based ink 68A is connected to an ink path (for viscosity measurement) 824. The ink path (for viscosity measurement) 824 is connected to a viscosity measuring device 45 in order to determine the viscosity of the pigment-based ink 68A in the main ink container 31. The viscosity measuring device 45 is connected to a solenoid valve (for viscosity measurement) 57 that opens and closes the ink path.

[0056] The solenoid valve (for viscosity measurement) 57 is connected to the pump (for circulation) 36 arranged in the ink path 822 via the confluent ink path 903. This allows the pigment-based ink 68A in the ink container 31 to be circulated through the viscosity measurement path, thereby measuring the viscosity of the pigment-based ink 68A. The viscosity measured in this manner is input to the control unit 7 (not shown in FIG. 2; see FIG. 3) and is used to control the viscosity of the pigment-based ink 68A in the ink container 31.

[0057] Next, the solvent supply paths (paths 831 and 833) of the inkjet recording apparatus 600 in this embodiment will be described.

[0058] 2, the main body 1 is provided with a solvent container 33 that holds a solvent 69A to be used for replenishing the solvent to the main ink container 31, for nozzle cleaning, or for head cleaning. The solvent container 33 is connected to a solvent supply path 831 at the portion immersed in the solvent 69A, and a pump (for solvent) 37 is disposed in the solvent supply path 831 and is used to suck and pump the solvent.

[0059] The pump (for solvent) 37 is connected to a branch path 922 to change the supply destination of the solvent 69A depending on the purpose. The branch path 922 is connected to a solenoid valve (for solvent supply) 53 in the solvent supply path 831 to open and close the flow path arranged in the solvent supply path 833, and the solenoid valve (for solvent supply) 53 is configured to be connected to the main ink container 31. Using this solvent supply path 831, the viscosity of the pigment-based ink 68A in the ink container 31 is controlled by the control unit 7.

[0060] Next, the ink supply path 806 of the inkjet recording apparatus 600 in this embodiment will be described.

[0061] 2, the main body 1 is provided with an auxiliary ink container 32 that holds refill ink 68C. The portion of the auxiliary ink container 32 that is immersed in the ink 68C is connected to an ink supply path 806. The ink supply path 806 is connected to a solenoid valve (for ink supply) 54 that opens and closes the ink supply path 806, and the solenoid valve (for ink supply) 54 is connected via a junction path 901 to a pump (for supply) 34 that is installed in the path 801 and is used to suck and pressure-feed the ink 68C.

[0062] The ink 68C in the auxiliary ink container 32 is then replenished into the main ink container 31 via the nozzle 21, the gutter 25, the ink path 811, the solenoid valve 50, and the pump .

[0063] Next, the nozzle cleaning paths (paths 831 and 835) of the inkjet recording apparatus 600 in this embodiment will be described.

[0064] 2, pump (for solvent) 37 disposed in nozzle cleaning path 831 is connected to nozzle cleaning path 835 via branch path 922. Nozzle cleaning path 835 is connected to electromagnetic valve (for nozzle cleaning) 55 for opening and closing the flow path. In addition, electromagnetic valve (for nozzle cleaning) 55 is connected to filter (for nozzle cleaning) 41 for removing foreign matter mixed in solvent 69A.

[0065] The filter (for nozzle cleaning) 41 is provided in the print head 2 via an ink path 821 that passes through the cable (for print head) 5, and is connected to a switching valve 26 that controls whether or not to send solvent 69A for cleaning to the nozzles 21.

[0066] Next, the main body circulation paths (paths 808 and 812) of the inkjet recording apparatus 600 in this embodiment will be described.

[0067] The ink path 802 is connected to a main body circulation path 808 via a branch path 921. The main body circulation path 808 is connected to a solenoid valve (for main body circulation) 58 that opens and closes the path, and the solenoid valve (for main body circulation) 58 is connected to a pump (for circulation) 35 installed in a main body circulation path 812 via a junction path 902.

[0068] Next, the head cleaning paths (paths 831 and 837) of the inkjet recording apparatus 600 in this embodiment will be described.

[0069] In FIG. 2, the pump (for solvent) 37 is connected to a head cleaning path 837 via a branch path 922, and a solenoid valve (for head cleaning) 56 for opening and closing the flow path is arranged in the head cleaning path 837, and the solenoid valve (for head cleaning) 56 is connected to a filter (for head cleaning) 43 for removing foreign matter mixed in the solvent 69A.

[0070] The output side of the filter (for head cleaning) 43 is connected to a cleaning nozzle 72 provided inside a cleaning tank 71 of the head mounting unit 3. The space inside the cleaning tank 71 is configured to communicate with a recovery container 4 installed below. The recovery container 4 is provided to collect the solvent after cleaning with the cleaning liquid (solvent) sprayed from the cleaning nozzle 72 grounded inside the cleaning tank 71.

[0071] A float 74 is provided in the recovery container 4 to detect the liquid level of the solvent after cleaning. When the float 74, which has a built-in magnet, reaches a predetermined liquid level, a magnetic sensor A76 detects the liquid level and outputs to the control unit (not shown in FIG. 2) that the cleaning liquid in the recovery container 4 has reached the predetermined liquid level.

[0072] Next, the air supply path (path 841) of the inkjet recording apparatus 600 in this embodiment will be described.

[0073] 2, the main body 1 is provided with a pump (for drying) 60 used to suck and pressurize air, and the pump (for drying) 60 forms an air intake port that communicates with the inside of the main body 1. The pump (for drying) 60 is connected to an air supply nozzle 73 provided inside the cleaning tank 71 of the head mounting unit 3 via an air supply path 841 that passes through the cable (for the head mounting unit) 6.

[0074] Next, the air suction path (path 843) of the inkjet recording apparatus 600 in this embodiment will be described.

[0075] The cleaning tank 71 provided in the head mounting unit 3 is connected to an air pump (for suction) 61 used to suck and pressurize air provided in the main body 1 via an air suction path 843 that passes through the cable (for head mounting unit) 6. The pump (for suction) 61 is connected to an exhaust duct connection part 62 that communicates with the outside of the main body 1.

[0076] [Control unit explanation] Next, the configuration of the control unit 7 of the inkjet recording apparatus 600 in this embodiment will be described.

[0077] FIG. 3 shows a schematic configuration of the control unit 7 and printing mechanism unit (main body 1 and print head 2) of the inkjet recording apparatus 600 in this embodiment.

[0078] 3, the inkjet recording apparatus 600 is equipped with a microprocessing unit (hereinafter referred to as MPU) 301, which is a control unit that controls the entire apparatus. It also has a bus line 302, which has the function of transmitting data, control signals, etc. between the devices that make up the control unit. For example, the bus line 302 is used to input data and detection signals required for the calculations of the MPU 301 from the devices, and to transmit data signals, address signals, and control signals to the devices.

[0079] Control programs and data required for the operation of MPU 301 are stored in read-only memory (ROM) 306. Data required by MPU 301 while the program is being executed is temporarily stored in rewritable memory (RAM) 307.

[0080] The operation and display unit 8 is used to input the print contents, setting values, etc., and to display the input data and print contents, etc. This operation and display unit 8 uses a touch input display panel in which transparent touch switches are superimposed on the surface of the liquid crystal display screen.

[0081] The head-mounted unit 3 can be controlled from the operation display unit 8 of the control unit 7, but the operation unit (start button 18 and stop button 19) is used when operating the head-mounted unit 3 near the head-mounted unit 3, rather than on the operation display unit 8. The display unit 20 is used when checking the operating status and abnormality messages, etc., of the head-mounted unit 3 near the head-mounted unit 3, rather than on the operation display unit 8.

[0082] The print head 2 of the inkjet recording device 600 is equipped with nozzles 21 that atomize and eject pigment-based ink 68A supplied under pressure from the main ink container 31. The nozzles 21 eject the ink in a columnar shape, the tip of which separates and is ejected as ink droplets 68B. The print head 2 also has a charging electrode 23 that surrounds the ink droplets 68B, and charges the ink droplets 68B in accordance with the print content.

[0083] Furthermore, the print head 2 deflects flying ink droplets 68B charged by the charging electrode 23 according to the amount of charge, causing them to fly toward a print target (not shown). These flying ink droplets then land on the print target, thereby performing printing. The deflection electrode 24 of the print head 2 is composed of a ground electrode 24B and a positive electrode 24A.

[0084] The print head 2 also includes a gutter 25 that captures ink particles 68B (unused ink) that were not used in printing, and a charge sensor 48 that generates a phase detection signal according to the amount of charge on ink particles 68B1 that are slightly charged among the ink particles 68B captured by the gutter 25.

[0085] The main body 1 is also provided with a pump (for recovery) 35 that recovers the ink (ink particles) captured by the gutter 25 into the ink container 31, and ink recovery paths 811 to 812 that connect the gutter 25 and the ink container 31.

[0086] The control unit 7 also has an excitation voltage generating circuit 331 that excites an electrostrictive element 22 (not shown) built into the nozzle 21 in order to impart regularity to the timing at which the ink column ejected from the nozzle 21 separates into ink particles 68B.

[0087] The control unit 7 also has a printing charge signal generating circuit 342 and a phase search charge signal generating circuit 341, a D / A converter 343 that converts the digital signal-form charge signals output from these circuits into analog voltage signals, and an amplifier circuit 344 that amplifies the analog signal-form voltage signals output from the D / A converter 343 to generate a charge voltage to be applied to the charging electrode 23.

[0088] Incidentally, instead of the configuration in which the printing charge signal generating circuit 342 and the phase search charge signal generating circuit 341 are provided, it is also possible to realize this by using only the printing charge signal generating circuit 342 and controlling the charge amount by the control unit. The inkjet recording apparatus 600 also includes a deflection voltage generating circuit 332 that generates a deflection voltage to be applied to the deflection electrode 24.

[0089] The inkjet recording apparatus 600 also includes an amplifier circuit 353 that amplifies the phase detection signal in the form of an analog signal output from the charge sensor 48, a phase determination circuit 351 that inputs the amplified phase detection signal and determines whether charging is good or bad, and an A / D converter 352 that inputs the amplified phase detection signal and performs A / D conversion.

[0090] In FIG. 3, the MPU 301 of the control unit 7 is connected via a bus line 302 to a liquid level detection circuit 313 for managing the liquid level in the main ink container 31, a pressure detection circuit 312 for detecting whether the pressure of the ink supplied to the nozzles 21 is at an appropriate value, a viscosity measurement circuit 311 for measuring with a viscosity meter 45 whether the viscosity of the pigment-based ink 68A supplied to the nozzles 21 is at an appropriate value for printing, a temperature detection circuit 316 for measuring with a temperature sensor 38 whether the temperature inside the main body 1 is at an appropriate value, a pump control circuit 314 for controlling each of the pumps 34 to 37 provided in the main body 1 for sucking and pumping the pigment-based ink 68A and the solvent 69A, and a solenoid valve drive circuit 315 for controlling the opening and closing operations of each of the solenoid valves 49 to 50 and 53 to 59 on each path, and controls each unit.

[0091] In addition, the MPU 301 is connected via bus line 302 to an air pump control circuit 321 for controlling pump 60 and pump 61, a collection container sensor detection circuit 322 for detecting using magnetic sensor A76 and magnet A75 that the collection container 4 is attached to the head mounting unit 3 and that the liquid (not shown) in the collection container 4 is not greater than a predetermined amount, a print head detection circuit 323 for detecting on the head mounting unit 3 side that the print head 2 is attached to the head mounting unit 3 using magnetic sensor B84 and magnet B86, and a head mounting unit detection circuit 324 for detecting on the print head 2 side that the print head 2 is attached to the head mounting unit 3 using magnetic sensor C28 and magnet C87, and is thereby configured to control each part.

[0092] Also, in FIG. 3, the MPU 301 of the control unit 7 is provided with, via a bus line 302, a stirrer 101 provided to stir the pigment-based ink 68A in the main ink container 31, a stirring mechanism control circuit 326 for controlling the rotor 103, and a stirring detection circuit 325 for detecting whether the pigment-based ink 68A in the main ink container 31 is being stirred.

[0093] The control unit 7 can use a computer. Specifically, the control unit 7 can be made up of an MPU 301, memories (306 and 307) that store programs for the operation of the MPU 301 and data and information required for operation, and a drive unit that operates the print head 2, head mounting unit 3, and components within the main body 1 in response to instructions from the MPU 301. A detailed description of the control unit 7 will be omitted here. [Main ink container description] The structure of the main ink container 31 in this embodiment will be described with reference to Fig. 4. Fig. 4 shows a vertical cross section of the main ink container 31 in this embodiment.

[0094] As shown in FIG. 4, a stirrer 101 is installed at the bottom of the main ink container 31, and the stirrer 101 is composed of a magnetic rotor 104 made of a magnetic material and a motor 102 for driving the magnetic rotor 104.

[0095] The main ink container 31 has a liquid storage section 111 for storing the pigment-based ink 68A therein. The liquid storage section 111 has a circular container bottom surface 111A to make it easier to stir the pigment-based ink 68A, a container side surface 111B that is connected to the container bottom surface 111A in a gentle R-shape, and a connection section 111C that is located above the container side surface 111B and is positioned higher than the ink reference liquid level 131 of the pigment-based ink 68A.

[0096] A stirrer 103 that rotates in conjunction with the magnetic rotor 104 of the stirrer 101 is provided on the container bottom surface 111A of the liquid storage section 111. The stirrer 101 and stirrer 103 are called the stirring mechanism. A permanent magnet or the like can be used as the magnetic body for the magnetic rotor 104 and stirrer 103. Influenced by the magnetic field of this magnet, the stirrer 103, which is made of a magnet, also rotates in conjunction with the magnetic body, causing convection in the ink and stirring the pigment-based ink 68A in the main ink container 31.

[0097] A connection block 113 made of an insulating resin material is provided above the liquid storage portion 111, and a seal member 112 made of an elastic material such as rubber to maintain airtightness is provided between the liquid storage portion 111 and the connection block 113. The connection block 113 is fixed to the liquid storage portion 111 by a fixing lid 114 that is fitted onto a threaded portion of a connection portion 111C of the liquid storage portion 111.

[0098] The connection block 113 includes an electrode (GND) 121, an electrode (reference) 122, and an electrode (abnormality detection) 123. A tip 121A of the electrode (GND) 121 is located below the ink reference liquid level 131 and is immersed in the pigment-based ink 68A held in the liquid storage section 111. A tip 122A of the electrode (reference) 122 is located at the same height as the ink reference liquid level 131.

[0099] A tip 123A of the electrode (abnormality detection) 123 is located above the ink reference liquid level 131 and below the seal member 112. The electrode (GND) 121, electrode (reference) 122, and electrode (abnormality detection) 123 are produced by processing a round bar of conductive stainless steel material, and are adapted to be assembled into the connection block 113 by, for example, press-fitting.

[0100] Outside the liquid storage portion 111, an electrode (GND) electric wire 121B is connected to the electrode (GND) 121, an electrode (reference) electric wire 122B is connected to the electrode (reference) 122, and an electrode (abnormality detection) electric wire 123B is connected to the electrode (abnormality detection) 123. In response to an instruction from the control portion 7, the electrode (GND) 121, the electrode (reference) 122, and the electrode (abnormality detection) 123 are configured to be able to receive or transmit electrical signals.

[0101] A circuit having a power supply for sending an electric signal to the electrode (GND) 121, the stirring detection sensor electrode 125, etc. may be provided in the control unit 7 or may be provided separately from the control unit 7. In response to an instruction from the control unit 7, an electric signal is sent to a selected electrode to detect whether or not there is electrical continuity, and the control unit 7 is configured to determine whether or not there is electrical continuity between the electrodes.

[0102] The pigment-based ink 68A stored in the liquid storage portion 111 is configured to contain a conductive material in its material composition. As a result, for example, if the electrode (reference) tip portion 122A is in contact with the pigment-based ink 68A, the electrode (reference) 122 and the electrode (GND) 121 are electrically connected, and if there is electrical continuity due to an electrical signal from the control portion 7, the control portion 7 can determine that the liquid level of the pigment-based ink 68A is the same as or higher than the ink reference liquid level 131.

[0103] Furthermore, if there is no electrical continuity, it can be determined that the ink level is lower than the ink reference liquid level 131. Furthermore, if there is electrical continuity between the electrode (abnormality detection) 123 and the electrode (GND) 121, this indicates that a large amount of liquid has flowed into the liquid storage section 111 due to some abnormality, causing the liquid level of the pigment-based ink 68A to rise abnormally, and the control section 7 determines that this is an abnormal state.

[0104] The connection block 113 is provided with an agitation detection sensor electrode 125 made of a thin, conductive stainless steel plate. The agitation detection sensor electrode 125 has a sensor electrode flat portion 125A, a sensor electrode inclined portion 125B, a sensor electrode contact portion 125C, a sensor electrode inclined portion 125D, and a sensor electrode lower end portion 125E.

[0105] Sensor electrode flat portion 125A is formed for assembly by a method such as press-fitting into connection block 113. Sensor electrode inclined portion 125B extends from sensor electrode flat portion 125A diagonally downward toward electrode (GND) 121.

[0106] The sensor electrode contact portion 125C is in contact with the electrode (GND) 121 when the stirrer 101 is stopped.

[0107] Sensor electrode inclined portion 125D extends from sensor electrode contact portion 125C in a direction away from electrode (GND) 121. Sensor electrode lower end portion 125E is located above tip portion 123A of the electrode (abnormality detection).

[0108] When not stirring, the stirring detection sensor electrode 125 and electrode (GND) 121 are configured to contact each other at the sensor electrode contact portion 125C, and when stirring is performed, the stirring detection sensor electrode 125 moves, causing the stirring detection sensor electrode 125 and electrode (GND) 121 to no longer contact each other.

[0109] The stirring detection sensor is composed of a stirring detection sensor electrode 125 and an electrode (GND) 121. When an electrical signal is conducted between the stirring detection sensor electrode 125 and the electrode (GND) 121, the stirring detection sensor is said to be conductive.

[0110] A flow detection plate 126 made of an insulating material is attached to the stirring detection sensor electrode 125 above the sensor electrode lower end 125E so as to be sandwiched and fixed with a mounting screw 127 and a mounting nut 128. The flow detection plate 126 extends downward so as to be immersed in the pigment-based ink 68A, and the flow detection plate lower end 126A is positioned above the stirrer 103 so as not to interfere with the stirring action of the stirrer 101.

[0111] The flow detection plate 126 is insulating, and even if the flow detection plate 126 is immersed in the pigment-based ink 68A, if the agitation detection sensor electrode 125 and the electrode (GND) 121 are not in contact, the agitation detection sensor will not be conductive.

[0112] When the stirrer 101 is stopped, the stirring detection sensor electrode 125 is electrically connected to the electrode (GND) 121, and is connected to the control unit 7 by an electric wire 125F for the stirring detection sensor electrode connected outside the liquid storage section 111.

[0113] In the configuration of this embodiment, the control unit 7 determines that the pigment-based ink 68A is not being stirred when there is electrical continuity between the stirring detection sensor electrode 125 and the electrode (GND) 121. The sensor electrode contact 125C is located above the liquid surface in the ink container in order to determine electrical continuity according to the stirring state.

[0114] The connection block 113 includes a supply pipe 801A connected to the path (for ink supply) 801, a recovery pipe 812A connected to the path (for ink recovery) 812, a solvent pipe 833A connected to the path (for solvent supply) 833, and an exhaust pipe (not shown) connected to the path (for exhaust) 814.

[0115] These supply pipe 801A, recovery pipe 812A, solvent pipe 833A, and exhaust pipe (not shown) are made of cylindrical stainless steel material and are assembled to connection block 113, for example, by press fitting.

[0116] The supply pipe 801A forms a supply pipe tip 801B that is located below the ink reference liquid level 131 and is immersed in the pigment-based ink 68A, and a supply tube 801C made of fluorine-based resin is connected to the outside of the liquid storage section 111.

[0117] A recovery tube 812B is connected to the recovery pipe 812A on the outside of the liquid storage section 111, and an ink recovery return section 113A is formed at the outlet to the liquid storage section 111 to prevent splashing when ink sucked and recovered from the gutter 25 is expelled into the liquid storage section 111.

[0118] The ink recovery return section 113A has an inner diameter larger than the flow path diameter of the recovery pipe 812A, and is designed to prevent ink splashes from soiling or solidifying the agitation detection sensor electrode 125. For this reason, the ink recovery return lower end 113B is formed to be positioned lower than the sensor electrode lower end 125E.

[0119] Furthermore, if the ink recovery return lower end 113B is immersed in the pigment-based ink 68A stored in the liquid storage section 111, the gas that has been sucked in together with the ink from the gutter 25 will also be expelled from the recovery pipe 812A, causing the liquid level of the pigment-based ink 68A to become unstable. For this reason, the ink recovery return lower end 113B is arranged higher than the tip 123A of the electrode (for abnormality detection).

[0120] A solvent tube 833C is connected to the solvent pipe 833A on the outside of the liquid storage section 111. A solvent pipe tip 833B, which is a solvent outlet for supplying the solvent 69A that dissolves the pigment-based ink 68A from the solvent pipe 833A to the liquid storage section 111, is disposed in the main ink container 31. The solvent pipe tip 833B is configured to be disposed above the sensor electrode inclined section 125B.

[0121] To adjust the concentration of the pigment-based ink 68A, the main ink container 31 is periodically (for example, about once every 15 minutes) replenished with solvent 69A from the solvent container 33. By adopting the configuration of this embodiment, when the solvent is replenished to the main ink container 31, the solvent 69A flows along the agitation detection sensor electrode 125 into the liquid storage section 111.

[0122] Therefore, by supplying a solvent, it is possible to prevent the contact area between the sensor electrode contact portion 125C and the electrode (GND) 121 from becoming difficult to separate due to adhesion and drying caused by the pigment-based ink 68A adhering to the contact portion.

[0123] In addition, the exhaust pipe (not shown) is positioned so that the tip of the pipe is not immersed in the pigment-based ink 68A, above the tip 123A of the electrode (for abnormality detection), and an exhaust tube 814B is connected to the outside of the liquid storage section 111.

[0124] [Explanation of the stirring detection sensor] Next, the operation of detecting the stirring state during stirring by the stirrer 101 of the main ink container 31 in this embodiment will be described with reference to Fig. 5. Fig. 5 shows the operating state of the stirrer 101 of the main ink container 31 in this embodiment.

[0125] 5 shows a state in which stirrer 101 is operating. The operation of the stirring mechanism is controlled by control unit 7. That is, motor 102 operates based on instructions from control unit 7, causing rotor 104 to rotate. Then, in conjunction with rotor 104, stirrer 103 stored in container bottom surface 111A of liquid storage unit 111 also rotates in the direction indicated by the arrow representing stirrer rotation direction 132.

[0126] Inside the liquid storage section 111, the rotation of the stirring bar 103 causes a rotational flow of the pigment-based ink 68A throughout the entire ink 68A, as shown by the arrows in the figure for the rotational flow 133 of the ink along the container side surface 111B. Due to this rotational flow of the ink, the ink reference liquid level 131 becomes higher at the container side surface 111B, changing to a state similar to the side wall side liquid level 131A during stirring, and the liquid level at the center of the liquid storage section 111 becomes lower, changing to a state similar to the center liquid level 131B during stirring, as shown in Figure 5.

[0127] In this way, when the stirrer 101 is operating to stir the pigment-based ink 68A, the rotational flow rate of the pigment-based ink 68A at the container side surface 111B increases, and the liquid level of the pigment-based ink 68A tends to rise. Even in such cases, the electrode (for detecting abnormalities) 123 is installed near the container side surface 111B to prevent the pigment-based ink 68A from overflowing from the liquid storage section 111.

[0128] As for the agitation detection sensor electrode 125, the flow detection plate 126 moves in the direction of the arrow of the ink rotation flow 133, so that the sensor electrode contact portion 125C and the electrode (GND) 121 are not electrically connected, and it can be determined that the pigment-based ink 68A is being agitated normally. As the ink rotation flow 133 is faster near the container side surface 111B than at the center of the container, the agitation detection sensor electrode 125 performs better when installed near the container side surface 111B.

[0129] Incidentally, in an inkjet recording device that uses pigment-based ink, if printing is not performed for a long period of time and the pigment-based ink is left without being stirred, the pigment components contained in the pigment-based ink will settle to the bottom of the ink container inside the ink container, and the pigment components will accumulate on the container bottom surface 111A, causing the stirrer 103 to stick, or the stirrer 101 to malfunction, which will prevent the stirrer 103 from rotating normally, making it impossible to stir the pigment-based ink and causing problems with the normal supply of pigment-based ink.

[0130] Furthermore, even if the control unit 7 instructs the stirrer 101 to operate, the pigment-based ink 68A is not stirred because the stirring bar 103 does not rotate normally, and the sensor electrode contact portion 125C and the electrode (GND) 121 remain in contact with each other.

[0131] Furthermore, in conventional inkjet recording devices that use pigment-based ink, the stirring mechanism operates only while the ink is being ejected during printing. Therefore, if the inkjet recording device is left unused for a long period of time, there is a high risk that the pigment-based ink will solidify within the ink path. This, combined with the aforementioned precipitation of the pigment components of the pigment-based ink within the ink container, can prevent the pigment-based ink from being supplied when printing is resumed, potentially making it impossible to print.

[0132] Therefore, in order to solve such problems, in this embodiment, in an inkjet recording device that uses pigment-based ink, when the inkjet recording device is paused (in pause mode) and not performing printing, the ink in the ink path is forcibly circulated and the ink in the ink container is forcibly stirred, thereby suppressing ink solidification in the ink path and precipitation of pigment components in the ink container, which occur when printing is not performed for a long period of time, and allowing the pigment-based ink to be ejected in a short time when printing is resumed.

[0133] The specific configuration will be explained next, but in reality, by executing a program in the control unit, control is performed to forcibly circulate ink in the ink path and stir the ink in the ink container when the inkjet recording device is in a pause mode where it is paused, i.e., when printing is not being performed. Below, the explanation will be given based on the control flow in the control unit 7.

[0134] [Explanation of ink agitation in the ink container and ink circulation in the ink path in pause mode] 6A to 6F, a control flow for agitating the pigment-based ink 68A in the ink container 31 and circulating the pigment-based ink 68A through the ink path at predetermined time intervals when the inkjet recording apparatus 600 is in the pause mode will be described. Note that in this description, please also refer to FIG. 2.

[0135] [Overall control flow description] First, FIG. 6A shows a control flow for determining whether the inkjet recording apparatus is at rest.

[0136] <Step S10> When the inkjet recording device is powered on, in step S10, it is determined whether or not a print process is to be performed. This determination can be made by detecting a print command or a pause command input by the operator. Alternatively, it can be determined that the device has transitioned to the pause mode when a predetermined time has elapsed since printing ended. For example, as shown in FIG. 11, in the pause mode, an input button can be selected to enable or disable the process of periodically circulating ink.

[0137] In short, it is sufficient to determine whether to execute the printing process or to execute the pause process that stops the printing process, and various conditions can be used for this determination. If it is determined in this control step that the printing process is to be executed, the process proceeds to step S20, and if it is determined that the printing process is not to be executed, the process proceeds to step S30. Hereinafter, the terms "print mode" and "pause mode" may be used, including in the claims.

[0138] <Step S20> Since it is determined in step S10 that printing processing is to be performed, normal printing processing (print mode) is performed in step S20. This printing processing is well known and is not the object of this embodiment, so its explanation is omitted. When the printing processing is completed, the process exits to END and ends.

[0139] <Step S30> Since it is determined in step S10 that the printing process is not being executed, pause processing (pause mode) is executed in step S30. The pause processing is performed when the inkjet recording device is paused and not performing printing, by forcibly circulating ink in the ink path and stirring the ink in the ink container, with the aim of suppressing ink solidification in the ink path and precipitation of pigment components in the ink container, which occur when printing is not performed for a long period of time, and ejecting pigment ink in a short time when printing is resumed. When this pause processing is completed, the process exits to END and ends.

[0140] [Overall control flow of hibernation mode] Next, a specific control flow of the above-mentioned pause processing will be described with reference to FIGS. 6B to 6F.

[0141] FIG. 6B shows a flow of processing in which the pigment-based ink 68A in the main ink container 31 is stirred and circulated through the ink path when the inkjet recording apparatus 600 is in the pause mode.

[0142] <Step S1> First, in step S1, when the inkjet recording apparatus 600 has been in a rest state for a predetermined time, an ink circulation process is started. When the ink circulation process is started, the process proceeds to step S100. <Step S100> In step S100, the control unit 7 operates the stirring mechanism attached to the bottom of the main ink container 31 to prevent the pigment components of the pigment-based ink from settling. If the stirring mechanism operates normally, the process proceeds to step S200; if it does not operate normally, abnormality processing 1 is executed. Abnormality processing 1 will be described later.

[0143] The stirring operation in step S100 may be stopped after stirring for a predetermined time and then proceed to step S200, or the stirring operation may be continued while proceeding to step S200. In the following, it is assumed that the process proceeds to step S200 after the stirring operation is performed.

[0144] <Step S200> In step S200, a check is made to see if the print head 2 and collection container 4 are attached to the head mounting unit 3. If it is confirmed that the print head 2 and collection container 4 are attached to the head mounting unit 3, the process proceeds to step S300, and if the print head 2 and collection container 4 are not attached, the process proceeds to step S400. Note that if the print head 2 and collection container 4 are not attached, it is assumed that the print head 2 is fixed to the print head fixing bracket 13 shown in Figure 1.

[0145] <Step S300> In step S300, ink circulation in the ink paths of the main body 1 and ink circulation within the print head 2 are performed, and it is determined whether or not there is an abnormality. Ink circulation within the print head 2 is performed to prevent ink from scattering to the outside because the print head 2 is attached to the head mounting unit 3. If both ink circulation processes are operating normally, the process proceeds to step S500, and if they are not operating normally, abnormality processing 2 is performed. Abnormality processing 2 will be described later.

[0146] <Step S400> In step S400, the ink circulation operation within the ink path of the main body 1 is performed, and it is determined whether or not there is an abnormality. Here, it is assumed that the print head 2 is fixed to the print head fixing bracket 13. Therefore, since there is a risk of ink scattering to the outside, the ink circulation operation within the print head 2 is not performed. If the ink circulation is operating normally, the process proceeds to step S500, and if it is not operating normally, abnormality processing 3 is performed.

[0147] <Step S500> In step S500, the ink circulation operation in step S300 or step S400 is performed for a predetermined time, after which the ink agitation and ink circulation operations are stopped and the system enters a standby state. Note that if the ink agitation operation in step S100 continues, control follows the operation of step S300 or step S400. In this way, by stopping the ink agitation and ink circulation operations, unnecessary power consumption is avoided. In this state, the system proceeds to step S600.

[0148] <Step S600> In step S600, it is determined whether printing has been resumed by the operator. If the operator has input a command to print, the process proceeds to step S700. If the operator has not input a command to print, the process proceeds to step S800.

[0149] <Step S700> In step S700, since a command to perform printing has been input, the pause process ends and the process of the flow shown in steps S10 and S20 in FIG. 6A is executed.

[0150] <Step S800> In step S800, since no instruction to print has been input, it is detected that a predetermined (here, fixed) time has elapsed. Once the predetermined time has elapsed, the process returns to step S100 and the operations of the above-mentioned respective control steps are repeated. The predetermined time is measured by a timer built into the MPU 301 of the control unit 7, starting from the time when step S1 is started. Thereafter, the process is executed every time the predetermined time has elapsed.

[0151] Next, the detailed control flow of steps S100, S200, S300, and S400 will be explained.

[0152] [Detailed control flow of step S100] FIG. 6C shows a control flow of the operation of the stirring mechanism in step S100.

[0153] <Step S101> In step S101, when the stirrer 101 is not operating, a sensor signal is detected to check whether the stirring detection sensor electrode 125 and the electrode (GND) 121 are electrically connected, and the process proceeds to step S102.

[0154] Step 102 In step S102, it is determined whether the stirring detection sensor, which is composed of the stirring detection sensor electrode 125 and the electrode (GND) 121, is electrically conductive. If it is determined that there is conductivity, the result is determined to be "Yes" (normal), and the process proceeds to step S103. On the other hand, if there is no conductivity in the stirring detection sensor electrode 125, the result is determined to be "No" (abnormal), and the process proceeds to step S107.

[0155] <Step S103> In step S103, the stirrer 101 starts stirring the pigment-based ink 68A in the main ink container 31 and the auxiliary ink container 32. Once the stirring of the pigment-based ink 68A has started, the process moves to step S104.

[0156] <Step S104> In step S104, the sensor signal is detected to confirm whether the pigment-based ink 68A in the main ink container 31 and the auxiliary ink container 32 is being stirred normally and whether the stirring detection sensor electrode 125 and the electrode (GND) 121 are in a non-conductive state, and then the process proceeds to step S105.

[0157] <Step S105> In step S105, it is determined whether the stirring detection sensor is non-conductive. If the stirring detection sensor is not conductive, the result is determined to be "Yes" (normal), and the process proceeds to step S106. On the other hand, if the stirring detection sensor is conductive, the result is determined to be "No" (abnormal), and the process proceeds to step S107.

[0158] <Step S106> In step S106, the stirrer 101 stirs the pigment-based ink 68A according to the period during which the inkjet recording apparatus 600 has been idle. Here, the longer the period during which the inkjet recording apparatus 600 has been idle, the more frequently the pigment-based ink 68A needs to be stirred, so the stirring time is set according to the idle period. This stirring time can be determined in advance by experiment or the like and stored in a table for use. Then, after stirring the pigment-based ink 68A, the process proceeds to step S200.

[0159] Step S107 to Step S109 Steps S107 to S109 correspond to abnormality processing 1, and in step S107, pause mode interruption processing is performed, in step S108 an interruption message is displayed on the operation display unit 8, and in step S109, the operation of the inkjet recording device 600 is terminated with the interruption message displayed on the operation display unit 8.

[0160] [Detailed control flow of step S200] FIG. 6D shows the control flow of the head-mounted sensor in step S200.

[0161] <Step S201> First, in step S201, it is confirmed whether the magnetic sensor B84 of the head mounting unit 3 is in the "ON" state (detecting the magnet B86 attached to the cover member 83) and whether the magnetic sensor C28 of the print head 2 is in the "ON" state (detecting the magnet C87 attached to the cleaning block 81). After this, the process proceeds to step S202. <Step S202> In step S202, if the result of the check in step S201 is that magnetic sensor B84 is in the "ON" state and magnetic sensor C28 is in the "ON" state, it is determined to be "YES" (print head 2 is attached to head attachment unit 3), and the process proceeds to step S203.

[0162] If the check result in step S201 shows that either magnetic sensor B84 or magnetic sensor C28 is in the "OFF" state, it is determined to be "NO" (print head 2 is not attached to head mounting unit 3), and the process proceeds to step S400.

[0163] <Step S203> In step S203, it is confirmed whether the magnetic sensor A76 of the head mounting unit 3 is in the "ON" state (detecting the magnet A75 of the waste toner container 4), and then the process proceeds to step S204.

[0164] <Step S204> In step S204, if the magnetic sensor A76 is in the "ON" state as a result of the check in step S203, it is determined to be "YES" (the collection container 4 is attached to the head mounting unit 3), and the process proceeds to step S300.

[0165] On the other hand, if the confirmation result in step S203 shows that the magnetic sensor A76 is in the "OFF" state, it is determined to be "NO" (the collection container 4 is not attached to the head mounting unit 3, or liquid (not shown) has accumulated in the collection container 4 and the float 74 is floating), and the process proceeds to step S400.

[0166] [Detailed control flow of step S300] 6E shows the control flow for ink path circulation in step S300 and ink circulation within the print head 2. At this time, the print head 2 is set in the head mounting unit 3.

[0167] <Step S301> In step S301, the pigment-based ink 68 in the main ink container 31 and the auxiliary ink container 32 is sufficiently stirred, and the ejection of atomized ink particles 68B from the nozzle 25 begins under the control of the print control means.

[0168] <Step S302> In step S302, it is determined whether ink is being ejected normally from the print head 2. If ink is being ejected normally, the answer is "Yes" and the process moves to step S303. If there is an abnormality in ink ejection, the answer is "No" and the process moves to step S308.

[0169] <Step S303> In step S303, with the print head 2 set in the head mounting unit 3, ink circulation processing is performed in the ink path of the main body 1 and within the print head 2, and this operation will be explained using Figure 7. The ink path through which ink is circulated shown in Figure 7 is the "first ink circulation path" referred to in the claims.

[0170] Figure 7 shows the inkjet recording device 600 of this embodiment in a state where the print head 2 is set in the head mounting unit 3, and the flow of liquid (ink) and air when ink is circulating through the ink path in the main body 1 and within the print head 2 is shown by thick lines (A1 to A7).

[0171] In the ink supply paths (paths 801-804), the solenoid valve (for supply) 49 is energized to open the flow path, the switching valve 26 is energized to connect the ink supply path to the nozzles 21, and the pump (for supply) 34 is operated, so that the pigment-based ink 68A stored in the ink container 31 of the main body 1 is supplied to the nozzles 21 of the print head 2 and ejected as ink droplets 68B from the nozzles 21, as indicated by the bold arrow A1. A voltage is applied to the ink droplets 68B by the charging electrode 23, and the charge amount is confirmed by the charge sensor 48.

[0172] In the ink recovery paths 811-812, when the solenoid valve (for recovery) 50 is energized to open the flow path and operate the pump (for recovery) 35, ink particles 68B and the air around the print head 2 are sucked in through the gutter 25 and sucked and pressure-fed into the ink container 31 of the main body 1, as shown by the thick arrow A2.

[0173] In the ink recovery paths 811-812, the pigment-based ink 68A and air flow in a gas-liquid mixture, so that the solvent component of the pigment-based ink 68A dissolves in the air, causing the air to turn into a solvent gas, which then flows into the ink container 31. The ink that flows into the ink container 31 is collected at the bottom, and the air that has turned into a solvent gas is discharged to the outside of the main body 1 as indicated by the thick arrow A3.

[0174] In the inkjet recording apparatus 600, the solvent component in the pigment-based ink 68A is thus discharged outside the apparatus as solvent gas, so that if the operation time is long, the ratio of the solvent component in the pigment-based ink 68A decreases, resulting in a high concentration of the pigment-based ink 68A. Conversely, if the operation time is short, the solvent 69A that has flowed into the ink container 31 during a nozzle cleaning process or the like will result in a low concentration of the ink.

[0175] Therefore, in paths (for viscosity measurement) 824 and 822, the solenoid valve (for viscosity measurement) 57 is energized to open the flow path and operate the pump (for circulation) 36, thereby sending the pigment-based ink 68A in the ink container 31 to the viscosity measuring device 45, as shown by the thick line of arrow A5, and periodically measuring the viscosity (converted to concentration) of the pigment-based ink 68A.

[0176] The detected viscosity value is input to the control unit 7. As a result, the control unit 7 controls the ink container 31 to be replenished with pigment-based ink 68C from the auxiliary ink container 32 when the concentration of the pigment-based ink 68A is low, and controls the ink container 31 to be replenished with solvent 69A from the solvent container 33 as indicated by the thick arrow A7 when the concentration of the pigment-based ink 68A is high. In this way, the inkjet recording apparatus 600 controls the viscosity of the pigment-based ink 68A so that it falls within the range of the control value.

[0177] In addition, in the ink circulation paths 821-822, when pigment-based ink 68A is supplied from the ink container 31 to the nozzle 21 as shown by the thick line of the arrow A1, the solenoid valve (for circulation) 59 is energized to open the flow path and operate the pump (for circulation) 36, thereby circulating the pigment-based ink 68A so that at least a portion of the pigment-based ink 68A supplied to the nozzle 21 is sucked into the pump (for circulation) 36 and returns to the ink container 31 as shown by the thick line of the arrow A3.

[0178] Furthermore, before energizing the switching valve 26, the solenoid valve (for circulation in the main body) 58 is energized to open the flow path, and the pump (for circulation) 36 is operated, thereby allowing the pigment-based ink 68A to be circulated through the path (for circulation in the main body) 808 as shown by the thick line of the arrow A6.

[0179] The pigment-based ink 68A in the ink container 31 and the pigment-based ink 68C in the auxiliary ink container 32 are stirred by the stirrer 101 and the stirring bar 103.

[0180] When ink circulation is being performed, a screen such as that shown in Fig. 9 is displayed. The screen shown in Fig. 9 is displayed on the touch panel type operation display unit 8.

[0181] That is, to enable the user to confirm that ink is circulating in the ink paths of the main body 1 and within the print head 2, a confirmation message 201 such as "Ink is currently circulating in the ink paths of the main body and within the print head. If you wish to end it, press the interrupt button" is displayed on the touch panel operation display unit 8. Also, to enable the user to interrupt the ink circulation, an interrupt button 202 is displayed on the touch panel display unit 8. Returning to Figure 6E, we will now proceed with the explanation of the next control step. <Step S304> In step S304, it is determined whether ink circulation in the ink path of the main body 1 is normal. This determination uses detection signals from the charge sensor 48 and pressure sensor 47. If ink circulation is normal, the determination is "Yes" and the process moves to step S305. On the other hand, if there is an abnormality in ink circulation, the determination is "No" and the process moves to step S308.

[0182] <Step S305> In step S305, since it is determined that the ink circulation is normal, ink ejection from the print head 2 is stopped, and the process moves to step S306.

[0183] <Step S306> In step S306, various sensor signals are detected to check whether the cleaning process inside the ink circulation path is normal, and the process proceeds to step S307.

[0184] <Step S307> In step S307, it is determined whether the cleaning process inside the ink circulation path is normal. This determination uses the detection signal of the pressure sensor 47. If the cleaning process inside the ink circulation path is normal, the determination is "Yes" and the process proceeds to step S500. If there is an abnormality in the cleaning process inside the ink circulation path, the determination is "No" and the process proceeds to step S312.

[0185] <Step S308> If an abnormality in ink circulation is detected in step S302 or step S304, ink ejection is interrupted in this step, and the process proceeds to step S309.

[0186] <Step S309> In step S309, a head cleaning process is performed, and the process proceeds to step S310.

[0187] <Step S310> In step S310, after the head has been washed in step S309, ink is ejected again, and after confirming whether the ink ejection abnormality has been corrected, the process proceeds to step S311.

[0188] <Step S311> In step S311, it is determined whether the ink ejection abnormality has been repaired. This determination uses the detection signal from the charge sensor 48. If the ink ejection abnormality has been repaired, the determination is "Yes," and the process moves to step S303, where ink circulation in the ink paths of the main body 1 and within the print head 2 is resumed. On the other hand, if the ink ejection abnormality has not been repaired, the determination is "No," and the process moves to step S312.

[0189] Step S312 to Step S314 Steps S312 to S314 correspond to abnormality processing 2, and in step S312, pause mode interruption processing is performed, in step S313 an interruption message is displayed on the operation display unit 8, and in step S314, the operation of the inkjet recording device 600 is terminated with the interruption message displayed on the operation display unit 8.

[0190] [Detailed control flow of step S400] 6F shows the control flow for ink circulation in the ink path in step S400. At this time, the print head 2 is fixed to the print head fixing metal fittings 13.

[0191] <Step S401> First, in step S401, it is confirmed whether ink circulation within the ink path of the main body 1 can be performed normally, and then the process proceeds to step S402.

[0192] <Step S402> In step S402, it is determined whether ink circulation within the ink path of the main body 1 can be performed normally. This determination uses the detection signal of the pressure sensor 47. If it can be performed normally, the determination is "Yes" and the process moves to step S403. On the other hand, if it cannot be performed normally, the determination is "No" and the process moves to step S405.

[0193] <Step S403> In step S403, ink circulation processing is performed within the ink path of the main body 1 without the print head 2 being set in the head mounting unit 3, and this operation will be explained using Figure 8. The ink path through which ink is circulated shown in Figure 8 is the "second ink circulation path" referred to in the claims.

[0194] Figure 8 shows the inkjet recording device 600 in this embodiment in a state where the print head 2 is not set in the head mounting unit 3, and the flow of liquid (ink) and air when ink is circulating within the main body 1 is shown by thick lines (B1 to B2).

[0195] In the main body 1, the solenoid valve (for supply) 49 and the solenoid valve (for circulation in the main body) 58 are energized to open the flow path, and the pump (for supply) 34 and the pump (for recovery) 35 are operated, so that the pigment-based ink 68A contained in the ink container 31 of the main body 1 passes through the solenoid valve (for supply) 49, the pump (for supply) 34, the filter (for supply) 39, the pressure regulating valve 46, the pressure sensor 47, the solenoid valve (for circulation in the main body) 58, the pump (for recovery) 35, and returns to the ink container 31, as shown by the thick line of the arrow B1, thereby circulating the pigment-based ink 68A.

[0196] In addition, in the main body 1, the solenoid valve (for viscosity measurement) 57 is energized to open the flow path and operate the pump (for circulation) 36, so that the pigment-based ink 68A contained in the ink container 31 of the main body 1 passes through the viscosity measuring device 45, the solenoid valve (for viscosity measurement) 57, and the pump (for circulation) 36 and returns to the ink container 31, as shown by the thick line of arrow B2, thereby circulating the pigment-based ink 68A.

[0197] Furthermore, if the viscosity of the pigment-based ink 68A is measured using the viscosity measuring device 45 at the timing of ink circulation within the main body 1, it will be easier to understand the state of the pigment-based ink 68A the next time it is used. When ink circulation is being performed, a screen like that shown in Figure 10 is displayed. The screen shown in Figure 10 is displayed on the touch panel type operation display unit 8.

[0198] That is, to allow the user to confirm that ink is circulating within the paths in the main body 1, a confirmation message 203 such as "Ink is currently circulating within the paths in the main body. If you wish to end it, press the pause button" is displayed on the touch panel operation display unit 8. Also, to allow the user to pause the ink circulation, a pause button 204 is displayed on the touch panel display unit 8. Returning to FIG. 6F, the next control step will be explained.

[0199] <Step S404> In step S404, it is determined whether ink circulation is normal. This determination uses the detection signal from pressure sensor 47. If ink circulation is normal, the determination is "Yes" and the process proceeds to step S500. On the other hand, if there is an abnormality in ink circulation, the determination is "No" and the process proceeds to step S405.

[0200] <Step S405> to <Step S407> Steps S405 to S407 correspond to abnormality processing 3, and in step S405, pause mode interruption processing is performed, in step S406 an interruption message is displayed on the operation display unit 8, and in step S407, the operation of the inkjet recording device 600 is terminated with the interruption message displayed on the operation display unit 8.

[0201] When the inkjet recording apparatus 600 selects to perform periodic ink circulation processing during the pause mode, a screen such as that shown in Fig. 11 is displayed. The screen shown in Fig. 11 is displayed on the touch panel type operation display unit 8.

[0202] When the inkjet recording device 600 is set to perform periodic ink circulation when in a resting state, the setting can be made by selecting the Enable button 206 displayed on the function selection screen 205 and then pressing the Confirm button 208.

[0203] On the other hand, if the periodic ink circulation is not to be performed, the setting can be made by selecting the disable button 207 displayed on the function selection screen 205 and then pressing the confirm button 208.

[0204] In this embodiment, the periodic execution of ink circulation processing during pause is enabled as a default setting, and ink can be prevented from solidifying in the ink path without the need to operate the function selection screen 205 again.

[0205] As described above, according to the present invention, an inkjet recording device comprises a nozzle that atomizes and ejects supplied pigment-based ink, a charging electrode that charges the ink particles ejected from the nozzle, a deflection electrode that deflects the ink particles charged by the charging electrode, a print head having a gutter that collects unused ink not used for printing, an ink container that stores the pigment-based ink and is equipped with a stirring mechanism that stirs the stored pigment-based ink, a first ink circulation path that supplies the pigment-based ink in the ink container to the print head and recovers the pigment-based ink into the ink container, a second ink circulation path that does not supply the pigment-based ink in the ink container to the print head but recovers it into the ink container, and a control unit that controls the operation of the print head and the stirring mechanism, wherein the control unit executes a print mode in which a printing operation is performed and a pause mode in which a printing operation is not performed, and in the pause mode, the control unit stirs the ink in the ink container and forcibly circulates ink in the first ink circulation path including the print head or the second ink circulation path not including the print head.

[0206] According to this, in an inkjet recording device that uses pigment-based ink, when printing is not being performed, the ink container is stirred and the ink is forcibly circulated in the ink circulation path, thereby suppressing ink solidification in the ink circulation path and precipitation of pigment components in the ink container, which occur when printing is not performed for a long period of time, and allowing the pigment-based ink to be ejected in a short time when printing is resumed.

[0207] The concept of steps S200, S300, and S400 in FIG. 6B can also be applied to a normal inkjet recording apparatus that does not have a pigment-based ink or a stirring mechanism for the ink (note that step S100 is not executed). In this case, the configuration is as follows: a print head having a nozzle for atomizing and ejecting ink supplied thereto, a charging electrode for charging the ink particles ejected from the nozzle, a deflection electrode for deflecting the ink particles charged by the charging electrode, and a gutter for collecting unused ink not used in printing; a head mounting unit that houses the print head and collects ink droplets ejected from the print head; an ink container for storing ink; a first ink circulation path including a print head that supplies ink in an ink container to the print head and collects the ink in the ink container while circulating the ink; a second ink circulation path that does not include a print head and that collects ink in the ink container while circulating it without supplying the ink to the print head; a control unit that controls the operation of the print head and the circulation of ink, The control unit It executes a print mode in which printing is performed and a pause mode in which printing is not performed, In the pause mode, ink is circulated in a first ink circulation path including a print head, or ink is circulated in a second ink circulation path not including a print head. The inkjet recording apparatus is characterized by the above.

[0208] The present invention is not limited to the above-described embodiments, but includes various modifications. The above-described embodiments have been described in detail to clearly explain the present invention, and are not necessarily limited to those including all of the described configurations. Furthermore, it is possible to replace part of the configuration of one embodiment with the configuration of another embodiment, and it is also possible to add the configuration of another embodiment to the configuration of one embodiment. It is also possible to add, delete, or replace other configurations with respect to the configuration of each embodiment. [Explanation of symbols]

[0209] 1...Main body, 2...Print head, 3...Head mounting unit, 4...Collection container, 5...Cable (for print head), 6...Cable (for head mounting unit), 7...Control unit, 8...Operation display unit, 11...Belt conveyor, 12A...Printing object, 12B...Printing object, 13...Print head fixing bracket, 16...Head base, 17...Protective cover, 18...Start button, 19...Stop button, 20...Display unit, 21...Nozzle, 23...Charging electrode, 24...Deflection electrode, 24A...Positive electrode, 24B...Ground electrode, 25...Gutter, 26...Switching valve, 28...Magnetic sensor C, 31...Ink container, 3 1A...Liquid level sensor, 32...Auxiliary ink container, 33...Solvent container, 34...Pump (supply), 35...Pump (recovery), 36...Pump (circulation), 37...Pump (for solvent), 39...Filter (supply), 40...Filter (recovery), 41...Filter (for nozzle cleaning), 43...Filter (for head cleaning), 45...Viscosity meter, 46...Pressure regulating valve, 47...Pressure sensor, 48...Charge sensor, 49...Solenoid valve (supply), 50...Solenoid valve (recovery), 53...Solenoid valve (for solvent refill), 54...Solenoid valve (for ink refill), 55...Solenoid valve (for nozzle cleaning), 56...Solenoid valve (head 1... for cleaning the head), 57... solenoid valve (for viscosity measurement), 58... solenoid valve (for circulation in the main body), 59... solenoid valve (for circulation), 60... pump (for drying), 61... pump (for suction), 62... exhaust duct connection part, 68A... pigment-based ink, 68B... ink particles, 68B1... ink particles, 68B2... charged charge, 68C... pigment-based ink, 69A... solvent, 71... cleaning tank, 72... cleaning nozzle, 73... air supply nozzle, 74... float, 76... magnetic sensor A, 81A... head mounting part, 83... cover member, 84... magnetic sensor B, 86... magnet B, 87... magnet C, 91... fixing part, 92... fixing jig (for contact lens), for bare), 93...joint portion, 101...stirrer, 102...motor, 103...stirring bar, 104...rotating body, 111...liquid storage portion, 111A...liquid storage portion bottom portion, 111B...liquid storage portion side portion, 111C...liquid storage portion connection portion, 112...sealing member, 113...connection block, 113A...ink recovery return portion, 113B...ink recovery return lower end portion, 114...fixed lid, 121...electrode (GND), 121A...electrode (GND) tip portion, 121B...electrode (GND) wire, 122...electrode (reference), 122A...electrode (reference) tip portion, 122B...electrode (reference) wire, 123...electrode (abnormality detection),123A...tip of electrode (abnormality detection), 123B...wire for electrode (abnormality detection), 125...stirring detection sensor electrode, 125A...flat part of stirring detection sensor electrode, 125B...inclined part of stirring detection sensor electrode, 125C...contact part of stirring detection sensor electrode, 125D...inclined part of stirring detection sensor electrode, 125E...lower end of stirring detection sensor electrode, 125F...wire for stirring detection sensor electrode, 126...flow detection plate, 126A...lower end of flow detection plate, 127...mounting screw, 128...mounting nut, 131...reference ink liquid level, 131A...liquid level on side wall side during stirring, 131B...central liquid level during stirring, 1 32...rotation direction of agitator, 133...rotational flow of ink, 201...confirmation message during ink circulation in the main body path and print head, 202...ink circulation interruption button in the main body path and print head, 203...confirmation message during ink circulation in the main body path, 204...ink circulation interruption button in the main body path, 205...function selection screen, 206...enable button, 207...disable button, 208...confirm button, 301...MPU, 302...bus line, 306...ROM, 307...RAM, 311...viscosity measurement circuit, 312...pressure detection circuit, 313...liquid level detection circuit, 314...pump control circuit, 315... solenoid valve drive circuit, 321... air pump control circuit, 322... collection container sensor detection circuit, 323... print head detection circuit, 324... head mounting unit detection circuit, 325... stirring detection circuit, 326... stirring mechanism control circuit, 331... excitation voltage generation circuit, 332... deflection voltage generation circuit, 341... phase search charging signal generation circuit, 342... printing charging signal generation circuit, 343... D / A converter, 344... amplifier circuit, 351... phase determination circuit, 352... A / D converter, 353... amplifier circuit, 600... inkjet recording device, 801 to 804... path (for supply), 80 1A...supply pipe, 801B...supply pipe tip, 801C...supply tube, 806...route (for refilling), 808...route (for circulating in the main body), 811-812...route (for recovery), 812A...recovery pipe, 812B...recovery tube, 814...route (for exhaust), 821-822...route (for circulating in the head), 824...route (for viscosity measurement), 831...route (for solvent supply), 833...route (for solvent refilling), 833A...solvent pipe, 833B...solvent pipe tip, 833C...solvent tube, 835...route (for nozzle cleaning), 837...route (for head cleaning),841...path (for air supply), 843...path (for air suction), 901 to 903...converging paths, 921 to 922...branching paths.

Claims

1. a print head having a nozzle for atomizing and ejecting ink supplied thereto, a charging electrode for charging the ink particles ejected from the nozzle, a deflection electrode for deflecting the ink particles charged by the charging electrode, and a gutter for recovering unused ink not used in printing; a head mounting unit that houses the print head and collects the ink droplets ejected from the print head; an ink container for storing the ink; a first ink circulation path including the print head that supplies the ink in the ink container to the print head and collects the ink into the ink container while circulating the ink; a second ink circulation path that does not include the print head and that circulates the ink in the ink container and collects the ink in the ink container without supplying the ink to the print head; a control unit that controls the operation of the print head and the circulation of the ink, The control unit A print mode in which a print operation is performed and a pause mode in which the print operation is not performed are executed, In the pause mode, the ink is circulated in the first ink circulation path including the print head, or the ink is circulated in the second ink circulation path not including the print head. An inkjet recording apparatus characterized by:

2. 2. The inkjet recording apparatus according to claim 1, The control unit In the pause mode, when the print head is housed in the head mounting unit, the ink is forcibly circulated in the first ink circulation path including the print head. An inkjet recording apparatus characterized by:

3. 2. The inkjet recording apparatus according to claim 1, The control unit In the pause mode, when the print head is not housed in the head mounting unit, the ink is forcibly circulated in the second ink circulation path that does not include the print head. An inkjet recording apparatus characterized by:

4. 2. The inkjet recording apparatus according to claim 1, The control unit In the pause mode, the circulation of the ink in the first ink circulation path including the print head or the circulation of the ink in the second ink circulation path not including the print head is performed every time a first predetermined time period elapses. An inkjet recording apparatus characterized by:

5. a print head having a nozzle for discharging a supplied pigment-based ink by atomizing it, a charging electrode for charging the ink particles discharged from the nozzle, a deflection electrode for deflecting the ink particles charged by the charging electrode, and a gutter for recovering unused ink that is not used in printing; a head mounting unit that houses the print head and collects the ink droplets ejected from the print head; an ink container that stores the pigment-based ink and is equipped with a stirring mechanism that stirs the pigment-based ink; a first ink circulation path including the print head that supplies the pigment-based ink in the ink container to the print head and collects the pigment-based ink into the ink container while circulating the pigment-based ink; a second ink circulation path that does not include the print head and that circulates the pigment-based ink in the ink container while recovering it in the ink container without supplying the pigment-based ink to the print head; a control unit that controls the operation of the print head and the stirring mechanism, The control unit A print mode in which a print operation is performed and a pause mode in which the print operation is not performed are executed, In the pause mode, the pigment-based ink in the ink container is stirred, and the ink is circulated in the first ink circulation path including the print head, or the ink is circulated in the second ink circulation path not including the print head. An inkjet recording apparatus characterized by:

6. 6. The inkjet recording apparatus according to claim 5, The control unit In the pause mode, when the print head is housed in the head mounting unit, the ink in the ink container is stirred and the ink in the first ink circulation path including the print head is circulated forcibly. An inkjet recording apparatus characterized by:

7. 6. The inkjet recording apparatus according to claim 5, The control unit In the pause mode, when the print head is not housed in the head mounting unit, the ink in the ink container is stirred and the ink in the second ink circulation path, which does not include the print head, is forcibly circulated. An inkjet recording apparatus characterized by:

8. 6. The inkjet recording apparatus according to claim 5, The control unit In the sleep mode, The agitation of the pigment-based ink in the ink container is stopped after a second predetermined time has elapsed, and thereafter, the circulation of the ink in the first ink circulation path including the print head or the circulation of the ink in the second ink circulation path not including the print head is performed. An inkjet recording apparatus characterized by:

9. 6. The inkjet recording apparatus according to claim 5, The control unit In the sleep mode, While the pigment-based ink in the ink container is continuously stirred, the ink is circulated in the first ink circulation path including the print head, or the ink is circulated in the second ink circulation path not including the print head. An inkjet recording apparatus characterized by:

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