Inkjet recording device

Abstract

To provide an inkjet recording device which can facilitate cleaning of a print head and easily recover a solvent (a cleaning fluid) used for the cleaning.SOLUTION: An inkjet recording device includes: a print head which receives supply of an ink to perform printing; and a body which includes an ink container for storing an ink and a solvent container for storing a solvent and supplies the ink in the ink container to the print head. The inkjet recording device includes a washing tank, a cleaning nozzle, and a recovery container. The print head is set within the washing tank, the solvent is jetted from the cleaning nozzle to wash the print head, and the solvent after washing is recovered by the recovery container.SELECTED DRAWING: Figure 4

Description

Technical Field

[0001] The present invention relates to an inkjet recording apparatus that continuously ejects ink from a nozzle and performs printing on a printing medium.

Background Art

[0002] As a technique related to nozzle cleaning in this technical field, the technique described in Japanese Patent Application Laid-Open No. 2002-103636 (Patent Document 1) is known. Patent Document 1 describes that "a cleaning jet is installed on the downstream side of the ink nozzle to be cleaned by the printing head, shifted to the side of the nozzle, and fixed. When the inkjet stops, a predetermined amount of solvent is ejected by this cleaning jet, and this hits the nozzle at a predetermined angle. In this way, the front surface of the droplet generator is cleaned (washed), and the ink residue is discharged toward the opposite side of the housing. Then, dry compressed air is blown through the cleaning jet toward the ink nozzle to dry the front part of the nozzle, and the ink residue adheres to the side part of the housing."

[0003] Also, as another technique related to nozzle cleaning, the technique described in Japanese Patent Application Laid-Open No. 2015-136934 (Patent Document 2) is known. Patent Document 2 describes that "it has a cleaning nozzle, that is, an ASC nozzle, for cleaning the nozzles of the head. This ASC nozzle is used to eject a cleaning liquid (solvent) from the ASC nozzle to clean the nozzle discharge port. Specifically, the ASC nozzle (cleaning nozzle) is arranged facing the nozzle discharge port inside the head. This ASC nozzle (cleaning nozzle) communicates with a solvent line and a solvent tank via an openable and closable air valve. When cleaning the nozzle, the air valve, which is an open / close valve, is opened, and the solvent supplied from the solvent tank is ejected from the ASC nozzle."

Prior Art Documents

Patent Documents

[0004] [Patent Document 1] Japanese Patent Publication No. 2002-103636 [Patent Document 2] Japanese Patent Publication No. 2015-136934 [Overview of the Initiative] [Problems that the invention aims to solve]

[0005] The technology described in Patent Document 1 involves ink residue adhering to the nozzles inside the print head, which then adheres to a different part (the side of the print head housing) after the print head is cleaned. Therefore, it becomes necessary for an operator to manually clean that part with a solvent, which is a cumbersome process. Furthermore, Patent Document 1 does not describe how to dispose of the solvent after cleaning.

[0006] Furthermore, while the technology described in Patent Document 2 involves spraying a solvent (cleaning solution) from a cleaning nozzle (ASC nozzle) installed inside the print head to clean the nozzle outlet, similar to Patent Document 1, manual work is required to remove ink residue adhering to the print head through cleaning. Also, Patent Document 2 does not describe how to dispose of the solvent (cleaning solution) after cleaning the print head.

[0007] Therefore, the object of the present invention is to provide an inkjet recording apparatus and a control method for an inkjet recording apparatus that can clean the print head and easily recover the solvent (cleaning solution) used to clean the print head. [Means for solving the problem]

[0008] To achieve the above-mentioned objectives, the present invention provides, as an example, an inkjet recording apparatus comprising: a print head that receives ink and performs printing; a main body that includes an ink container for containing ink and a solvent container for containing solvent, and supplies the ink in the ink container to the print head, wherein the print head comprises a nozzle that ejects the ink as ink particles, a charging electrode that charges the ink particles ejected from the nozzle in accordance with the printing content, a deflection electrode that changes the flight direction of the charged ink particles, and a gutter that collects the ink particles that do not contribute to the printing, and further comprising a head cleaning unit that includes a cleaning tank for setting the print head, a cleaning nozzle that sprays the solvent toward the print head set in the cleaning tank for cleaning, a collection container provided at the bottom of the cleaning tank for collecting the solvent after cleaning, and a drive unit that supplies the solvent to the cleaning nozzle.

[0009] Another example of the present invention is a control method for an inkjet recording apparatus having a print head that receives ink and performs printing, and a main body that includes an ink container for containing ink and a solvent container for containing solvent, and supplies the ink in the ink container to the print head, wherein the print head is set inside a cleaning tank equipped with a cleaning nozzle for spraying the solvent, and then the solvent is sprayed from the cleaning nozzle to clean the print head, and the solvent after cleaning is collected in a collection container provided at the bottom of the cleaning tank. [Effects of the Invention]

[0010] According to the present invention, it is possible to provide an inkjet recording apparatus and a control method for an inkjet recording apparatus that can easily clean the print head and easily recover the solvent (cleaning solution) used to clean the print head. [Brief explanation of the drawing]

[0011] [Figure 1]A perspective view showing the usage of the inkjet recording device in Example 1 of the present invention. [Figure 2] This is a perspective view showing the print head set in the cleaning unit in Example 1. [Figure 3] This is a perspective view showing the head cleaning unit fixed to the main body in Example 1. [Figure 4] This figure shows the path configuration of the inkjet recording device in Example 1. [Figure 5] This diagram shows the path configuration of the inkjet recording device with the head cleaning unit removed in Example 1. [Figure 6] This diagram shows the routing configuration of the head cleaning unit after it has been removed from the inkjet recording device in Example 1. [Figure 7] This is a fluid path diagram showing the liquid flow during the head cleaning process in Example 1, indicated by thick lines. [Figure 8] This is a fluid path diagram showing the airflow during the head drying process in Example 1, indicated by a thick line. [Figure 9] This is a fluid path diagram showing the flow of ink and solvent during the ink and solvent replenishment operation in Example 1, indicated by thick lines. [Figure 10] This is a fluid path diagram showing the flow of ink during the ink circulation process in Example 1, indicated by thick lines. [Figure 11] This is a diagram showing the configuration of the print head in Example 1. [Figure 12] This is a diagram showing the configuration of the head cleaning unit in Example 1. [Figure 13] This is a cross-sectional view of the head cleaning unit in Example 1 with the print head set in the head cleaning unit. [Figure 14] This is a magnified view of the area around the print head in Figure 13. [Figure 15] This is a cross-sectional view of the head cleaning unit, showing the flow of liquid inside the head cleaning unit during the head cleaning process in Example 1, indicated by a thick line. [Figure 16] In Example 1, the liquid level detection of the recovery container in each state is shown. [Figure 17] In Example 1, it is a cross-sectional view of the head cleaning unit when the liquid draining operation of the recovery container is being performed. [Figure 18] It is an external perspective view of the inkjet recording apparatus in Example 2 of the present invention. [Figure 19] In the inkjet recording apparatus in Example 2, it is a perspective view showing the state where the print head is set in the cleaning unit. [Figure 20] It is a diagram showing the path configuration of the inkjet recording apparatus in Example 2.

Mode for Carrying Out the Invention

[0012] Hereinafter, specific examples of the present invention will be described with reference to the drawings. Note that the present invention is not limited to the examples described below. Also, in the following figures, the same device is given the same number (reference sign), and the description of the device that has already been explained may be omitted.

[0013] ≪Example 1≫ <Usage state> First, the usage state of the inkjet recording apparatus 600 in Example 1 of the present invention will be described with reference to FIGS. 1 to 3. FIG. 1 is a perspective view showing the usage state of the inkjet recording apparatus 600 in the present example, and FIG. 2 is a perspective view showing the state where the print head 2 is attached to the head cleaning unit 4 in the inkjet recording apparatus 600 in the present example. FIG. 3 is a perspective view showing the state where the head cleaning unit 4 is fixed to the main body 1 in the inkjet recording apparatus 600.

[0014] First, as shown in FIG. 1, the inkjet recording apparatus 600 according to the present example includes a main body 1, a print head 2 connected to the main body 1 by a conduit (for print head) 5, and a head cleaning unit 4 connected to the main body 1 by a conduit 6 for the head cleaning unit.

[0015] The inkjet recording device 600 is installed, for example, on a production line in a factory where food or beverages are produced, and the main unit 1 is installed in a location where space necessary for periodic maintenance work can be secured. The print head 2 is fixed to a print head fixing bracket 13 installed near the belt conveyor 11 and is installed in close proximity to the objects to be printed on 12A to 12B that are fed along the production line such as the belt conveyor 11 in the direction of arrow XX. In addition, a protective cover 17 is attached to the print head 2 for the purpose of protecting the internal components of the print head 2.

[0016] In such an inkjet recording device 600, a control unit 10 (specific configuration not shown) installed inside the main body 1 controls the amount and timing of charging of ink particles 68B ejected from nozzles 21 attached to the print head 2. Specifically, the control unit 10 controls the process so that the ink particles 68B, which are charged and deflected as the object to be printed (before printing) 12A passes near the print head 2, adhere to the object to be printed (during printing) 12B, and then print is performed. The control unit 10 also controls solenoid valves, pumps, etc., installed inside the main body 1 to control the flow of ink and solvent. The control unit 10 can use a computer. Specifically, the control unit 10 can consist of a microprocessing unit (MPU), a memory that stores a program for the operation of the MPU and data and information necessary for its operation, and a print drive unit that operates the print head and the components inside the main body 1 according to the instructions of the MPU. Details of the control unit 10 are omitted here.

[0017] The head cleaning unit 4 is installed around the print head 2. In this embodiment, the head cleaning unit 4 is fixed by combining a fixing jig fitting part 93, which is attached to the head cleaning unit 4, with a fixing jig A (for conveyor) 92, which is attached to the belt conveyor 11. The head cleaning unit 4 has a print head insertion part 72A, which is an opening for inserting the print head 2 into the head cleaning unit 4.

[0018] Furthermore, the head cleaning unit 4 includes a start button 63 for initiating the cleaning process of the print head 2, a stop button 64 for stopping the cleaning process of the print head 2, and a display unit 65 for allowing the operator to recognize confirmation messages, alarms, or abnormalities.

[0019] The main body 1 has a fixing jig (for the main body) 91 for fixing the head cleaning unit 4, and the head cleaning unit 4 can also be used by removing it from the fixing jig (for the conveyor) 92 and attaching it to the fixing jig (for the main body) 91. In this embodiment, the head cleaning unit 4 is fixed to the belt conveyor 11, but in the inkjet recording device 600 of this embodiment, the head cleaning unit 4 can be freely attached to a location that is easy for the user to operate.

[0020] Next, with reference to Figure 2, the state in which the print head 2 is set in the head cleaning unit 4 in the inkjet recording device 600 will be described. The print head 2 is inserted from the tip of the print head 2 into the print head insertion section 72A of the head cleaning unit 4 and set. In this embodiment, by setting the print head 2 in the head cleaning unit 4 in this manner, the inkjet recording device 600 can clean the print head 2 with a solvent (cleaning liquid) supplied from the main body 1 side via the conduit 6.

[0021] Furthermore, it is preferable that the length of the conduit (for the head cleaning unit) 6 connecting the main unit 1 and the head cleaning unit 4 be the same as, or longer than, the conduit (for the print head) 5 connecting the main unit 1 and the print head 2 of the inkjet recording device. This is to ensure flexibility in the placement of the head cleaning unit 4.

[0022] Next, with reference to Figure 3, the state in which the head cleaning unit 4 is fixed to the main body 1 in the inkjet recording device 600 will be described. The head cleaning unit 4 can be fixed to the main body 1 by combining the fixing jig 91, which is assembled to the main body 1, with the fixing jig fitting part 93. By making the head cleaning unit 4 fixable to the main body 1, it becomes possible to install the head cleaning unit 4 even if there is no space to attach the head cleaning unit 4 to the belt conveyor 11 or the like.

[0023] <Route Configuration> Next, the routing configuration of the inkjet recording device 600 in this embodiment will be explained using Figure 4. Figure 4 is a diagram showing the overall routing configuration of the inkjet recording device 600 in this embodiment.

[0024] First, the ink supply paths (paths 801 to 803) of the inkjet recording device 600 in this embodiment will be described. In Figure 4, the main body 1 is equipped with an ink container 31 that holds circulating ink 68A. The ink container 31 is equipped with a liquid level sensor 31A that detects whether or not the liquid inside the ink container 31 has reached a reference liquid level, which is an appropriate amount to be held inside.

[0025] The ink container 31 is connected to the supply path 801 at the point where it is immersed in the ink 68A, and a solenoid valve (supply) 49 for opening and closing the path is installed along the way. Furthermore, the path 801 is connected to a pump (supply) 34 installed in the path 802 via a merging path 901, which is used to draw in and pump the ink 68A. The output side of the pump (supply) 34 is connected to a filter (supply) 39 for removing foreign matter mixed in the ink 68A.

[0026] The filter (for supply) 39 is connected to a pressure regulating valve 46 that adjusts the pressure of the ink 68A pumped from the pump (for supply) 34 to the appropriate pressure for printing. The pressure regulating valve 46 is connected to a pressure sensor 47 that measures the pressure of the ink 68A supplied to the nozzle 21. The path 802 in which the pressure sensor 47 is located passes through the conduit (for print head) 5 and is connected to a switching valve 26 located in the print head 2 that controls whether or not to supply ink 68A to the nozzle 21.

[0027] The switching valve 26 is connected via a path 803 to a nozzle 21 equipped with an outlet 21A for discharging ink 68A. The switching valve 26 is a three-way solenoid valve, and is connected to an ink supply path 802 and a nozzle cleaning path 812, allowing the supply of ink 68A and solvent 69A to the nozzle 21 to be switched. In the straight direction of the discharge outlet 21A of the nozzle 21, there is 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 used for printing, and a gutter 25 for capturing ink particles 68B that are not used for printing and are therefore not charged or deflected and fly in a straight line.

[0028] Next, the ink recovery path 804 of the inkjet recording device 600 in this embodiment will be described. In Figure 4, the gutter 25 is connected to the path 804, and a charge sensor 48 is located in the path 804 to detect whether ink particles 68B to which an electric charge has been added by the charging electrode 23 are being recovered. The path 804 passes through the conduit (for the print head) 5 and is connected to a filter (for recovery) 40 located inside the main body 1 that removes foreign matter mixed in the ink, and the filter (for recovery) 40 is connected to a solenoid valve (for recovery) 50 that opens and closes the path.

[0029] The solenoid valve (for recovery) 50 is connected to a pump (for recovery) 35 that sucks up the ink particles 68B captured by the gutter 25, and the pump (for recovery) 35 is connected to the ink container 31. By opening the solenoid valve 50 and driving the pump 35, the ink particles 68B captured by the gutter 25 are recovered into the ink container 31. The ink container 31 is connected to a path 805 in an upper space that does not come into contact with the ink 68A, and the path 805 is configured to communicate with the outside of the main body 1.

[0030] Next, the ink circulation paths (paths 806-807) of the inkjet recording device 600 in this embodiment will be described. In addition to the ink supply path 803, the nozzles 21 provided in the print head 2 are connected to a path 806 that passes through a conduit (for the print head) 5. A solenoid valve (for circulation) 51, which is provided in the main body 1 and opens and closes the flow path, is located in this path 806.

[0031] The solenoid valve (for circulation) 51 is connected to the path 807 via the merging path 902, and a pump (for circulation) 36 that draws ink from the nozzle 21 is located in the path 807. The pump (for circulation) 36 is connected to the ink container 31.

[0032] Next, the viscosity measurement paths (paths 808 and 807) of the inkjet recording device 600 in this embodiment will be described. In Figure 4, the ink container 31 is connected to path 808 in the portion immersed in the ink 68A. Path 808 is connected to a viscometer 45 via path 801 to determine the viscosity of the ink 68A in the ink container 31. The viscometer 45 is connected to a solenoid valve (for viscosity measurement) 52, which opens and closes the path. The solenoid valve (for viscosity measurement) 52 is connected to a pump (for circulation) 36 located in path 807 via a merging path 902. This configuration allows the ink 68A in the ink container 31 to be circulated through the viscosity measurement paths and its viscosity to be measured. After measurement, the results are input to the control unit 10 (not shown) and used to control the viscosity of the ink 68A in the ink container 31.

[0033] Next, the solvent supply path (paths 809-810) of the inkjet recording device 600 in this embodiment will be described. In Figure 4, the main body 1 is equipped with a solvent container 33 that holds solvent 69A for use in supplying solvent to the ink container 31, nozzle cleaning, or head cleaning. The solvent container 33 is connected to path 809 at the portion immersed in solvent 69A, and a pump (for solvent) 37 used for aspirating and pumping the solvent is located in path 809. The pump (for solvent) 37 is connected to a branch path 903 to change the supply destination of the solvent 69A depending on the purpose. In the solvent supply path, the branch path 903 is connected to a solenoid valve (for solvent supply) 53 to open and close the flow path located in path 810, and the solenoid valve (for solvent supply) 53 is connected to the ink container 31.

[0034] Next, the ink supply path 811 of the inkjet recording device 600 in this embodiment will be described. In Figure 4, the main body 1 is equipped with an auxiliary ink container 32 that holds replenishment ink 68C. The auxiliary ink container 32 is connected to the path 811 at the portion immersed in the ink 68C. The path 811 is connected to a solenoid valve (for ink supply) 54 that opens and closes the path, and the solenoid valve (for ink supply) 54 is connected via a merging path 901 to a pump (for supply) 34 installed in the path 802, which is used to suck and pump the ink 68C. The ink 68C in the auxiliary ink container 32 is then replenished into the ink container 31 via the nozzle 21, gutter 25, path 804, solenoid valve 50, and pump 35.

[0035] Next, the nozzle cleaning paths (paths 809 and 812) of the inkjet recording device 600 in this embodiment will be described. In Figure 4, the pump (for solvent) 37 located in path 809 is connected to path 812 via branch path 903. Path 812 is connected to a solenoid valve (for nozzle cleaning) 55 for opening and closing the flow path. The solenoid valve (for nozzle cleaning) 55 is connected to a filter (for nozzle cleaning) 41 for removing foreign matter mixed in the solvent 69A. The filter (for nozzle cleaning) 41 is located inside the print head 2 via path 812 passing through the conduit (for print head) 5 and is connected to a switching valve 26 for controlling whether or not to send the cleaning solvent 69A to the nozzles 21.

[0036] Next, the head cleaning paths (paths 809, 821-822) of the inkjet recording device 600 in this embodiment will be described. In Figure 4, the pump (for solvent) 37 is connected to path 821 via branch path 903, and path 821 is connected to path 822 via a connecting part (for head cleaning) 59A and a fitting (for head cleaning) 60A for relaying to the drive unit 3 incorporated inside the main body 1. A solenoid valve (for nozzle cleaning) 56 for opening and closing the flow path is located in path 822, and the solenoid valve (for nozzle cleaning) 56 is connected to a filter (for head cleaning) 42 for removing foreign matter mixed in the solvent 69A.

[0037] The filter (for head cleaning) 42 is located inside the head cleaning unit 4 via a path 822 that passes through the conduit (for head cleaning unit) 6, and is connected to the filter (for cleaning nozzle) 43 to remove any foreign matter that may initially enter the path 822. The output side of the filter (for cleaning nozzle) 43 is connected to a cleaning nozzle 74 located inside the cleaning tank 71 of the head cleaning unit 4. Here, the space inside the cleaning tank 71 is configured to communicate with a recovery container 73 installed at the bottom.

[0038] Next, the solvent reuse paths (paths 823-824 and path 807) of the inkjet recording device 600 in this embodiment will be described. In Figure 4, the head cleaning unit 4 is equipped with a recovery container 73 that holds the recovered solvent 69B after head cleaning, which flows in by gravity after being used for head cleaning. A filter (for the recovery container) 77 is assembled in the recovery container 73 to prevent foreign matter mixed in during head cleaning from flowing into path 823. The recovery container 73 is connected to path 823 in the portion immersed in the recovered solvent 69B. Path 823 passes through the conduit (for the head cleaning unit) 6 and connects to a filter (solvent reuse) 44 in the drive unit 3 inside the main body 1. This filter 44 is to prevent fine foreign matter contained in the recovered solvent 69B from mixing with the ink 68A.

[0039] Furthermore, the output side of the filter (solvent reuse) 44 is connected to a solenoid valve (solvent reuse) 57 via path 823 to open and close the flow path. Path 823, where the solenoid valve (solvent reuse) 57 is located, is connected to path 824 via connection parts (solvent reuse) 59B and 60B, which relay the main body 1 and the drive unit 3. Path 824 is connected to a pump (for circulation) 36 located in path 807 via a confluence path 902. This allows the recovered solvent 69B held in the recovery container 73 to be replenished to the ink container 31 in the main body 1 via the drive unit 3. This replenishment makes it possible to adjust the ink concentration (viscosity), and the solvent can be reused for viscosity adjustment. In other words, when the viscosity detected by the viscosity meter 45 exceeds a predetermined value, the control unit 10 supplies the solvent 69B used for cleaning the inside of the recovery container 73 to the ink container 31 via path 823, filter 44, solenoid valve 57, connection part 60B, path 824 branch 902, path 807, and pump 36.

[0040] Next, the head drying air path 825 of the inkjet recording device 600 in this embodiment will be described. In Figure 4, the drive unit 3 housed in the main body 1 is equipped with a pump (for supplying drying air) 38 used for drawing in and pumping air, and the pump (for supplying drying air) 38 forms an air intake port that communicates with the inside of the main body 1. The pump (for supplying drying air) 38 is connected to an air nozzle 75 provided inside the cleaning tank 71 of the head cleaning unit 4 via a path 825 that passes through the conduit (for the head cleaning unit) 6.

[0041] <Head cleaning unit integrated structure> The configuration of the head cleaning unit 4 being incorporated into the inkjet recording device 600 in this embodiment will be explained with reference to Figures 4 to 6. Figure 4 is a path diagram showing the state in which the head cleaning unit 4 is incorporated into the inkjet recording device 600 in this embodiment. Figure 5 is a path diagram showing the state in which the head cleaning unit 4 is not incorporated into the inkjet recording device 600 in this embodiment. And Figure 6 is a path diagram of the head cleaning unit 4 and the drive unit 3.

[0042] In Figure 5, the main body 1 of the inkjet recording device 600 is shown with the head cleaning unit 4 and drive unit 3 removed. A sealing plug 61A is attached to the connection part (for head cleaning) 59A of the path 821 connected to the cleaning nozzle 74 of the head cleaning unit 4 in order to block the flow path. Similarly, a sealing plug 61B is attached to the connection part (for solvent reuse) 59B of the path 824 connected to the recovery container 73 of the head cleaning unit 4 in order to block the flow path. The main body 1 also has a storage area 58 for arranging the drive unit 3.

[0043] Next, in Figure 6, the head cleaning unit 4 is shown detached from the main body 1 of the inkjet recording device 600. The head cleaning unit 4 is connected to the drive unit 3 by a conduit (for the head cleaning unit) 6. The drive unit 3 is composed of a pump (for supplying dry air) 38, a solenoid valve (for head cleaning) 56, a solenoid valve (for solvent reuse) 57, and a filter (for head cleaning) 42 and a filter (for solvent reuse) 44.

[0044] Thus, in the inkjet recording device 600 of this embodiment, the main unit 1 and the head cleaning unit 4 can be separated. This makes it easy to carry the head cleaning unit 4, the drive unit 3, and the conduit 6 connecting the drive units 3 and 4 as a single head cleaning device. When cleaning the print head 2, this head cleaning device is attached to the main unit 1 and used.

[0045] <Operation and Fluid Flow> Next, the operation of the inkjet recording device 600 in this embodiment will be described.

[0046] Figure 7 is a fluid path diagram showing the flow of solvent and air during head cleaning in the inkjet recording apparatus 600 according to Example 1, with thick lines indicating the flow. In Figure 7, the inkjet recording device 600 is in a state where the print head 2 is set (inserted) into the head cleaning unit 4 for cleaning. In the head cleaning path (path 809, paths 821-822), the solenoid valve (for head cleaning) 56 is energized to open the flow path and the pump (for solvent) 37 is operated, so that the solvent can be supplied to the head cleaning unit 4 as shown by the thick line of arrow A. That is, the solvent 69A contained in the solvent container 33 of the main body 1 can be supplied to the cleaning nozzle 74 assembled in the cleaning tank 71 of the head cleaning unit 4.

[0047] The cleaning nozzle 74 sprays the solvent 69A toward the print head to clean it. Specifically, some of the solvent 69A supplied to the cleaning nozzle 74 is discharged toward the nozzle 21 surrounded by the protective cover 17 of the print head 2, as shown by the thick line of arrow B, and the other part is discharged toward the protective cover 17 on the outside of the print head 2, as shown by the thick line of arrow C. The solvent 69A discharged from the cleaning nozzle 74, as shown by the thick line of arrow B, cleans the components assembled inside the print head 2, such as the nozzle 21, the charging electrode 23, the deflection electrode 24, and the gutter 25, and then flows downward by gravity, as shown by the thick line of arrow E. The solvent 69A that has dripped down to the bottom of the cleaning tank 71 flows toward the recovery container 73, as shown by the thick line of arrow F, and is collected inside the recovery container 73 as recovered solvent 69B.

[0048] In the ink circulation path (paths 806-807), the solenoid valve (for circulation) 51 is energized to open the flow path, and the pump (for circulation) 36 is activated. As shown by the thick line of arrow G, a portion of the solvent 69A that hits the nozzle 21 is sucked out from the nozzle 21A and collected in the ink container 31 of the main body 1. In this way, the head cleaning process allows the inside of the nozzle 21 and the ink circulation path 806-807 to be cleaned with solvent 69A.

[0049] Furthermore, in the ink recovery path 804, the solenoid valve (for recovery) 50 is energized to open the flow path, and the pump (for recovery) 35 is activated. As shown by the thick line of arrow H, a portion of the solvent 69A that hits the gutter 25 is sucked out of the gutter 25 and recovered into the ink container 31 of the main body 1. In this way, the head cleaning process allows the inside of the gutter 25 and the ink recovery path 804 to be cleaned with solvent 69A.

[0050] Next, Figure 8 is a fluid path diagram showing the airflow in the inkjet recording device 600 in this embodiment when the head drying process is being performed, indicated by a thick line. In Figure 8, the inkjet recording device 600 is in a state where the print head 2 is set in the head cleaning unit 4, and the head drying process is performed after the head cleaning process is completed. In the head cleaning path 825, compressed air is supplied to the air nozzle 75 assembled in the cleaning tank 71 of the head cleaning unit 4 by operating the pump (for supplying drying air) 38 installed in the main body 1, as indicated by the thick line of arrow J.

[0051] The air supplied to the air nozzle 75 is partially discharged towards the charged electrode 23 and other components surrounded by the protective cover 17 of the print head 2, as indicated by the thick line of arrow K, and the remaining portion is discharged towards the protective cover 17 on the outside of the print head 2, as indicated by the thick line of arrow L. The air discharged from the air nozzle 75, as indicated by the thick line of arrow K, dries the components assembled inside the print head 2, such as the nozzle 21, charged electrode 23, deflection electrode 24, and gutter 25.

[0052] In the ink recovery path 804, the solenoid valve (for recovery) 50 is energized to open the flow path, and the pump (for recovery) 35 is activated, causing a portion of the air to be drawn in from the gutter 25 and pumped into the ink container 31 of the main body 1, as indicated by the thick line of arrow M. In the ink circulation path (paths 806-807), the solenoid valve (for circulation) 51 is energized to open the flow path, and the pump (for circulation) 36 is activated, causing a portion of the air to be drawn in from the nozzle 21 and pumped into the ink container 31 of the main body 1, as indicated by the thick line of arrow N. The air that has flowed into the ink container 31 is then discharged to the outside of the main body 1 through the exhaust path 805, as indicated by the thick line of arrow P. In this way, by drawing air in from the gutter 25 and nozzle 21 during the head drying process, the amount of solvent gas discharged around the head cleaning unit 4 can be reduced. If the air flow rate drawn in by the gutter 25 and nozzle 21 from inside the cleaning tank 71 is greater than the air flow rate supplied from the air nozzle 75 to the inside of the cleaning tank 71, then the diffusion of solvent gas around the head cleaning unit 4 can be minimized.

[0053] Next, Figure 9 is a fluid path diagram showing the flow of ink, solvent, and air in the inkjet recording device 600 in this embodiment when the circulation control of ink 68A, the replenishment control of ink 68C, and the replenishment control of solvents 69A and 69B are being performed during operation. In Figure 9, the inkjet recording device 600 is shown to be ready for printing as the print head 2 has been removed from the head cleaning unit 4. In the ink supply paths 801 to 803, the solenoid valve (for supply) 49 is energized to open the flow path and the pump (for supply) 34 is operated, so as shown by the thick lines of arrows Q and R, the ink 68A contained in the ink container 31 of the main body 1 is supplied to the nozzle 21 of the print head 2 and discharged from the nozzle 21 as ink particles 68B.

[0054] In the ink recovery path 804, the solenoid valve (for recovery) 50 is energized to open the flow path and activate the pump (for recovery) 35, causing ink particles 68B and air around the print head 2 to be drawn in from the gutter 25 and pumped under pressure into the ink container 31 of the main body 1, as indicated by the thick line of arrow S. In the ink recovery path 804, ink 68A and air flow in a gas-liquid mixture state, so the solvent components of ink 68A dissolve into the air, and the air becomes a solvent gas that flows into the ink container 31. The ink 68B that flows into the ink container 31 is contained at the bottom, and the air that has become a solvent gas is discharged to the outside of the main body 1 as a solvent gas, as indicated by arrow T.

[0055] In the inkjet recording device 600, the solvent component in the ink 68A is discharged outside the machine as solvent gas. As the operating time increases, the proportion of the solvent component in the ink 68A decreases, resulting in a high concentration of ink 68A. Therefore, in the viscosity measurement paths 808 and 807, the solenoid valve (for viscosity measurement) 52 is energized to open the flow path, and the pump (for circulation) 36 is operated to send the ink 68A in the ink container 31 to the viscosity meter 45, as indicated by arrows V and W, and to periodically measure the concentration of ink 68A. This measured viscosity is input to the control unit 10. As a result, if the concentration of ink 68A is low, the control unit 10 replenishes the ink container 31 with ink 68C from the auxiliary ink container 32, and if the concentration of ink 68A is high, it replenishes the ink container 31 with recovered solvent 69B from the recovery container 73 or with solvent 69 from the solvent container 33.

[0056] In the ink supply path (paths 811 and 802), the solenoid valve (for ink supply) 54 is energized to open the flow path, and the solenoid valve (for supply) 49 is de-energized to close the flow path. With this state, the pump (for supply) 34 is operated to supply ink 68C from the auxiliary ink container 32 to the nozzle 21, where it is discharged as ink particles 68B. The ink 68C is then supplied to the ink container 31 via the ink recovery path 804.

[0057] In the solvent reuse pathways (823-824 and 807), when the concentration of ink 68A is high, the solenoid valve (solvent reuse) 57 is energized to open the flow path and the pump (for circulation) 36 is activated, so the recovered solvent 69B contained in the recovery container 73 of the head cleaning unit 4 is supplied to the ink container 31 of the main body 1. Then, in the solvent supply pathways 809-810, when the concentration of ink 68A is high and the liquid level in the recovery container 73 is detected to be below the minimum liquid level detection unit 76B of the liquid level sensor 76, the solenoid valve (for solvent supply) 53 is energized to open the flow path and the pump (for solvent) 37 is activated, so the solvent 69A contained in the solvent container 33 is supplied to the ink container 31.

[0058] Next, Figure 10 is a fluid path diagram showing the ink flow in the inkjet recording device 600 in this embodiment, with the print head 2 set in the head cleaning unit 4, and the ink circulation process being performed. The inkjet recording device 600 can reduce problems at the start of operation the next time it is used by performing ink circulation periodically (about once every 2 to 3 days), even if it is not used for a period of one to two weeks. Therefore, Figure 10 will explain the control method for automatically circulating the ink 68A periodically.

[0059] In the ink supply path (paths 801-803), the solenoid valve (for supply) 49 is energized to open the flow path and the pump (for supply) 34 is activated, so that the ink 68A contained in the ink container 31 of the main body 1 is supplied to the nozzle 21 of the print head 2, as shown by the thick line of arrow AA, and is ejected from the nozzle 21 as ink particles 68B.

[0060] In the ink recovery path 804, the solenoid valve (for recovery) 50 is energized to open the flow path, and the pump (for recovery) 35 is activated. As shown by the thick line of arrow BB, ink particles 68B and air around the print head 2 are drawn in from the gutter 25 and pumped into the ink container 31 of the main body 1. The ink 68B that flows into the ink container 31 is contained at the bottom, and the air that has become a solvent gas is discharged to the outside of the main body 1 as a solvent gas, as shown by arrow T. Then, as shown by arrow DD, the concentration of ink 68A is periodically measured by the viscosity meter 45 to control the concentration (viscosity) of ink 68A so that it remains within a certain range.

[0061] In this embodiment of ink circulation, even if, due to a malfunction, the ink particles 68B ejected from the nozzle 21 do not enter the gutter 25, the charge sensor 48 can detect this, and furthermore, it is possible to prevent the ink 68B that has escaped from the gutter 25 from contaminating the area around the inkjet recording device 600. Even if the charge sensor 48 fails to accurately detect that the ink particles 68B have not entered the gutter 25 due to a malfunction or other reason, the maximum liquid level detection unit 76A of the liquid level sensor 76 provided in the recovery container 73 can detect the overflow of ink 68B and stop the supply of ink 68A to the nozzle 21.

[0062] Furthermore, the inkjet recording device 600 can also perform periodic automatic head cleaning control in addition to periodic automatic ink 68A circulation control. This makes it possible to further prevent problems during the next use.

[0063] <Print head structure> Next, the specific configuration of the print head 2 of the inkjet recording device 600 according to Embodiment 1 will be described with reference to Figure 11. Figure 11 is a partial cross-sectional view showing the configuration of the print head in this embodiment. In Figure 11, (a) shows the state in which the protective cover door 18 of the print head 2 is closed, and (b) shows the state in which the protective cover door 18 of the print head 2 is open.

[0064] In Figure 11(a), the print head 2 comprises a head base 16, a conduit (for the print head) 5 connecting the main body 1 and the print head 2, and a printing opening 17A through which ink particles 68B used for printing pass. A protective cover 17 is attached to the head base 16. The head base 16 is equipped with a switching valve 26, a nozzle 21 connected to the switching valve 26 via a tube 803A, a charging electrode 23, a deflection electrode 24, and a gutter 25. The print head 2 is also equipped with a temperature sensor A27 for detecting ambient temperature and using it for various controls. When the protective cover 17 is attached, the space enclosed by the head base 16 and the protective cover 17 is protected from impacts during maintenance.

[0065] Furthermore, a cleaning opening 17B is formed in the protective cover 17, and the cleaning opening 17B can be opened and closed by a protective cover door 18 assembled to the protective cover 17. The mounting position of the protective cover door 18 is determined by a pin 20 fixed to the protective cover 17, and the protective cover door 18 slides within the range of the elongated hole 18B formed in the protective cover door 18 in the direction of arrow DC, or in the opposite direction of arrow DC (arrow DO).

[0066] The protective cover 17 forms a seating surface 17D, and a door closing spring 19 is assembled to the seating surface 17D such that a load is applied to the protective cover door 18 in the direction of arrow DC. The door closing spring pushes the back surface of the opening / closing support portion 18A formed on the protective cover door 18 in the direction of arrow DC, causing the protective cover door 18 to cover the washing opening 17B. At this time, the protective cover door 18 comes to rest at a position where the lower end of the opening 17C formed on the protective cover 17 and the lower end of the door 18C formed on the protective cover door 18 meet.

[0067] A magnet A29 is mounted on the lower end 18C of the door, and a proximity sensor A28 is mounted on the protective cover door 18 that detects when the magnet A29 approaches within a certain distance. When the protective cover door 18 covers the cleaning opening 17B, the proximity sensor A28 does not detect the magnet A29 because it is far away. Therefore, it can be determined that the protective cover 17 covers the cleaning opening 17B, and the nozzle 21, charging electrode 23, and deflection electrode 24 are protected.

[0068] Next, Figure 11(b) will describe the state in which the protective cover door 18 of the print head 2 is open. The opening / closing support part 18A of the protective cover door 18 is pushed in the direction of arrow DO, and the door closing spring 19 is compressed. The door then stops at a position where the lower end 18C of the protective cover door 18 and the upper end 17E of the opening of the protective cover 17 are in contact. The proximity sensor A28 mounted on the protective cover 17 can detect when the distance to the magnet A29 mounted on the protective cover door 18 is below a certain distance.

[0069] In Figure 11, the protective cover door 18 is a sliding type that automatically opens when the print head is inserted into the cleaning tank 71, but the present invention is not limited to this. That is, any configuration of a door that can be opened during cleaning is acceptable in order to facilitate the cleaning of the internal structural components of the print head (nozzle 21, charging electrode 23, deflection electrode 24, gutter 25, etc.). For example, a door that can be opened and closed vertically or horizontally may be formed on the protective cover. Alternatively, the protective cover itself may be made openable and closable.

[0070] <Structure of the head cleaning unit> Next, the configuration of the head cleaning unit 4 of the inkjet recording device 600 according to Example 1 will be described with reference to Figure 12. Figure 12 is a diagram of the configuration of the head cleaning unit 4 in Example 1 (a cross-sectional view of the cleaning nozzle 74).

[0071] In Figure 12, the head cleaning unit 4 includes a cleaning tank 71 in which the print head 2 is housed during head cleaning, a lid block 72 installed above the cleaning tank 71 and comprising a print head insertion section 72A for setting the print head 2 into the head cleaning unit 4, and a recovery container 73 for storing the recovered solvent 69B used in the head cleaning process.

[0072] A lid member 83 is assembled to the lid block 72 to prevent foreign matter such as dust from entering the inside of the cleaning tank 71 through the opening of the print head insertion part 72A when the print head 2 is not set in the print head insertion part 72A. The lid member 83 is assembled to the lid block 72 via a lid hinge 82. This lid member 83 has a lid member projection 83A to reduce frictional resistance when inserting the print head 2 into the head cleaning unit 4.

[0073] The lid block 72 is then fitted by press-fitting a cleaning nozzle 74 for spraying solvent 69A for cleaning the print head 2, and an air nozzle 75 for blowing air to dry the print head 2, which has been wet with solvent 69A after cleaning.

[0074] The cleaning nozzle 74 has a liquid flow path section 74A formed inside the cleaning nozzle 74 so as to extend from the nozzle 21 toward the gutter 25 when the print head 2 is set in the head cleaning unit 4, a liquid discharge hole A section 74B connected to the liquid flow path section 74A for spraying solvent 69A aimed at the nozzle 21, a liquid discharge hole B section 74C connected to the liquid flow path section 74A for spraying solvent 69A aimed at the deflection electrode 24, and a liquid discharge hole C section 74D connected to the liquid flow path section 74A for spraying solvent 69A aimed at the surface of the protective cover 17 where the printing opening 17A is formed. The liquid flow path section 74A formed in the cleaning nozzle 74 is connected to a liquid flow path section 72B formed in the lid block 72.

[0075] The air nozzle 75 has an air passage section 75A formed inside the air nozzle 75 so as to extend from the nozzle 21 toward the gutter 25 when the print head 2 is set in the head cleaning unit 4, an air discharge hole A section 75B connected to the air passage section 75A for spraying air aimed at the space between the charged electrodes 23, and an air discharge hole B section 75C connected to the air passage section 75A for spraying air aimed at the protective cover 17. Here, the air passage section 75A formed in the air nozzle 75 is connected to an air passage formed in the lid block 72.

[0076] The head cleaning unit 4 is equipped with a cleaning tank 71 at the bottom of the lid block 72 for housing the print head 2 during cleaning. The cleaning tank 71 has a side wall portion 71A formed to prevent the solvent 69A ejected from the cleaning nozzle 74 from splashing into the surroundings, and a liquid outlet portion 71D for allowing the solvent 69A discharged from the cleaning nozzle 74 to flow out to the bottom of the cleaning tank 71. The cleaning tank 71 also has a conical inner bottom portion 71C that is inclined so that the liquid outlet portion 71D is at its lowest point, in order to facilitate the collection of the solvent 69A at the liquid outlet portion 71D. Inside the cleaning tank 71, a temperature sensor B84 is installed to detect the ambient temperature of the head cleaning unit 4 and use it for various control functions.

[0077] Furthermore, the head cleaning unit 4 is equipped with a recovery container 73 at the bottom of the cleaning tank 71 for storing the solvent 69A used during head cleaning. The recovery container 73 stores the solvent 69A used during head cleaning that has dripped out from the liquid outlet 71D of the cleaning tank 71 as recovered solvent 69B. The recovery container 73 has a liquid storage section 73A that holds the recovered solvent 69B, and the liquid storage section 73A is sealed by the combination of the upper part of the recovery container 73 and the lower part of the cleaning tank 71. The recovery container 73 also has a liquid level sensor 76 for detecting when the liquid level 69C of the recovered solvent 69B falls below a certain value and when the liquid level 69C rises above a certain value.

[0078] The recovery container 73 has a filter (for recovery container) 77 assembled at the bottom of the liquid reservoir 73A to remove foreign matter that has entered the recovered solvent 69B during head cleaning or other processes. Below the filter (for recovery container) 77, a liquid reservoir 73B is formed to contain the filtered recovered solvent 69B. The recovery container 73 has a solvent reuse channel 73C connected to the liquid reservoir 73B, and the solvent reuse channel 73C is connected to tube 823A via a reuse fitting 80. This tube 823A forms part of the solvent reuse paths 823-824 and 807, and the recovered solvent 69B is supplied to the ink container 31 via tube 823A.

[0079] Furthermore, the recovery container 73 has a liquid discharge channel 73D connected to a liquid reservoir 73B, and the liquid discharge channel 73D is connected to a tube 86 made of a fluorine-based solvent-resistant material via a discharge fitting A81. A discharge fitting B87 is assembled to the tube 86 by press-fitting its end into the outlet portion opposite to the discharge fitting A81. The cleaning tank 71 has a tube fixing section 71G, and the discharge fitting B87 is fixed to the tube fixing section 71G by a nut 89. A sealing member 88 is assembled to the tube fixing section 71G. The sealing member 88 seals the space between the discharge fitting B87 and the cleaning tank 71 so that the solvent 69A does not flow out of the cleaning tank 71 and the recovery container 73.

[0080] Furthermore, a communication hole 71F is formed in the center of the tube fixing portion 71G of the cleaning tank 71. When the discharge fitting B87 is fixed to the cleaning tank 71, the internal space of the cleaning tank 71 and the internal space of the tube 86 are at the same pressure. Therefore, the internal space of the recovery container 73, which is connected to the cleaning tank 71 at the liquid outlet portion 71D, and the internal space of the tube 86 are at the same pressure. As a result, the liquid level 69C of the recovered solvent 69B and the liquid level 69D of the tube 86 are at the same level. This allows the liquid volume in the recovery container 73 to be confirmed by checking the liquid level in the tube 86, even if the recovery container 73 is opaque.

[0081] Furthermore, a liquid connector 78 connected to the liquid flow path section 72B is assembled to the lid block 72, and a tube 822A is connected to the liquid connector 78 by press-fitting or other means. This tube 822A forms part of the head cleaning paths 809 and 821-822, and is connected to the solvent container 33 via tube 822A. In addition, an air connector 79 connected to the air flow path section 72C is assembled to the lid block 72, and a tube 825A is connected to the air connector 79 by press-fitting or other means. This tube 825A forms part of the 825... path (for drying air) 825, and is connected to the pump (for supplying drying air) 38 via tube 825A.

[0082] The head cleaning unit 4 is covered by a cover 85 so that tubes 822A, 823A, and 825A are not exposed to the outside of the head cleaning unit 4. The cover 85 is fixed so as to sandwich the top of the lid block 72 and the bottom of the recovery container 73. The conduit (for the head cleaning unit) 6 is assembled to the bottom of the cover 85 so as not to protrude outwards and interfere with other production equipment.

[0083] Next, the configuration of the inkjet recording device 600 according to Example 1 with the print head 2 set in the head cleaning unit 4 will be explained using Figures 13 and 14. Figure 13 is a partial cross-sectional view of the head cleaning unit 4 of Example 1 with the print head 2 set in the head cleaning unit 4. Figure 14 is an enlarged view of the configuration of the print head 2, cleaning nozzle 74, and the surrounding area in Figure 13.

[0084] In Figures 12 to 14, the print head 2 is set in the head cleaning unit 4. The lid member 83 of the head cleaning unit 4 is opened by inserting the print head 2 into the print head insertion section 72A. The print head 2 is pushed in until the nozzle 21, the charging electrode 23, the deflection electrode 24, and the gutter 25 are inside the cleaning tank 71. The head cleaning unit 4 is designed so that the print head 2 does not shift position, as the inner wall surface of the hole in the print head insertion section 72A and the outer wall surface of the print head 2 engage. Furthermore, the head base 16 of the print head 2 stops when it abuts against the print head support section 71B formed in the cleaning tank 71, thus stabilizing the position of the print head 2 when it is set in the head cleaning unit 4.

[0085] A sensor mounting section 71E is formed in the cleaning tank 71, and a proximity sensor B90 is assembled to the sensor mounting section 71E. A magnet B30 is assembled to the head base 16 of the print head 2, and when the distance between the magnet B30 and the proximity sensor B90 approaches a certain distance or less, the proximity sensor B90 can detect it. When the print head 2 is set in the head cleaning unit 4, the magnet B30 and the proximity sensor B90 are close enough that the proximity sensor B90 detects it, and it can be determined that the print head 2 is set in the head cleaning unit 4.

[0086] Furthermore, when the print head 2 is set in the head cleaning unit 4, the opening / closing support portion 18A of the protective cover door 18 abuts against the door support portion 72D formed on the lid block 72. In the case of the print head 2, the weight of the print head 2 is greater than the spring force of the door closing spring 19, so the door closing spring 19 is compressed. The print head 2 moves downward until it abuts against the print head support portion 71B, but the position of the protective cover door 18 does not move below the door support portion 72D, so the cleaning opening 17B that was covered by the protective cover door 18 is opened. The proximity sensor A28 assembled on the protective cover 17 detects when the distance to the magnet A29 assembled on the protective cover door 18 is below a certain distance, so it can be determined that the print head 2 is set in the head cleaning unit 4.

[0087] <How to use the head cleaning unit> Next, the operation of the inkjet recording device 600 according to Example 1, when the print head 2 is set in the head cleaning unit 4 and the head cleaning process is being performed, will be explained with reference to Figure 15. Figure 15 is a cross-sectional view of the head cleaning unit 4 showing the flow of liquid inside the head cleaning unit 4 when the head cleaning process of Example 1 is being performed.

[0088] In Figure 15, the inkjet recording device 600 performs a head cleaning process by ejecting solvent 69A from the cleaning nozzle 74 to clean the print head 2. The solvent 69A supplied to the cleaning nozzle 74 is ejected as solvent 69A in the directions indicated by arrow EE (direction for ejecting solvent 69A from liquid ejection hole A 74B aimed at the nozzle 21) and arrow FF (direction for ejecting solvent 69A from liquid ejection hole B 74C aimed at the deflection electrode 24). The solvent 69A enters the inside of the protective cover 17 through the cleaning opening 17B, and is sprayed onto components such as the nozzle 21 and deflection electrode 24 assembled to the print head 2, thereby cleaning off dirt caused by ink 68A that has adhered during operation or maintenance of the inkjet recording device 600.

[0089] The solvent 69A sprayed onto components such as the nozzle 21 and deflection electrode 24 assembled to the print head 2 flows down in the direction indicated by arrow HH due to gravity, and when the print head 2 is set in the head cleaning unit 4, the charged electrode 23 and the gutter 25 located below the deflection electrode 24 can be cleaned by the solvent 69A. In addition, the solvent 69A supplied to the cleaning nozzle 74 is ejected as solvent 69A in the direction indicated by arrow GG (direction in which the solvent 69A is ejected from the liquid discharge hole C part 74D, aiming at the surface of the protective cover 17 where the printing opening 17A is formed), spraying the solvent 69A onto the protective cover 17 and cleaning off ink 68A stains adhering to the outside of the print head 2.

[0090] During the head cleaning process, the solvent 69A used to clean components such as the nozzle 21, charging electrode 23, deflection electrode 24, gutter 25, and protective cover 17 located on the print head 2 drips down in the directions indicated by arrows JJ and KK, flows into a recovery container 73 installed at the bottom of the head cleaning unit 4, and is collected as recovered solvent 69B in the liquid storage section 73A.

[0091] Next, the detection of the liquid level in the recovery container 73 in each state of the inkjet recording device 600 according to Example 1 will be explained with reference to Figure 16. Figure 16 is a cross-sectional view centered on the recovery container 73 of the head cleaning unit 4 in this embodiment. In Figure 16, (a) shows a state in which the liquid level sensor 76 of the recovery container 73 does not detect either the maximum liquid level detection unit 76A or the minimum liquid level detection unit 76B. Figure 16(b) shows a state in which the liquid level sensor 76 detects the maximum liquid level detection unit 76A because the liquid level of the recovery solvent 69B in the recovery container 73 has increased. And Figure 16(c) shows a state in which the liquid level sensor 76 detects the minimum liquid level detection unit 76B because the liquid level of the recovery solvent 69B in the recovery container 73 has decreased.

[0092] In Figure 16(a), the liquid level sensor 76 installed inside the recovery container 73 includes a float portion 76C that displaces up and down with the liquid level 69C of the recovered solvent 69B, a maximum liquid level detection portion 76A installed below the liquid outlet portion 71D of the cleaning tank 71 and detecting when the float portion 76C approaches, and a minimum liquid level detection portion 76B installed below the maximum liquid level detection portion 76A and above the filter (for the recovery container) 77 and detecting when the float portion 76C approaches. The float portion 76C is in a state where neither the maximum liquid level detection portion 76A nor the minimum liquid level detection portion 76B is detecting anything. In this state, the recovered solvent 69B contained in the recovery container 73 can be normally supplied to the ink container 31. The inkjet recording device 600 can also perform a head cleaning process by setting the print head 2 in the head cleaning unit 4 and ejecting the solvent 69A from the cleaning nozzle 74.

[0093] Next, we will explain the state in Figure 11(b) where the liquid level sensor 76 detects the maximum liquid level detection unit 76A because the liquid level of the recovered solvent 69B in the recovery container 73 has increased. In the recovery container 73, the amount of recovered solvent 69B increases due to repeated head cleaning processes, and the liquid level C rises. The liquid level sensor 76 can determine that the liquid level of the recovered solvent 69B has increased because the float unit 76C, which is displaced in conjunction with the liquid level 69C, and the maximum liquid level detection unit 76A are approaching a certain distance or less. When this state is detected, the inkjet recording device 600 controls the system so as not to eject the solvent 69A from the cleaning nozzle 74 in order to prevent the recovered solvent 69B from overflowing from the recovery container 73.

[0094] Next, in Figure 11(c), we will explain the state in which the liquid level sensor 76 detects the minimum liquid level detection unit 76B because the liquid level of the recovered solvent 69B in the recovery container 73 has decreased. In the recovery container 73, since the head cleaning process has not been performed for a certain period of time, the amount of recovered solvent 69B has decreased and the liquid level 69C has become low. The liquid level sensor 76 can determine that the liquid level of the recovered solvent 69B has decreased because the float unit 76C, which is displaced in conjunction with the liquid level, and the minimum liquid level detection unit 76B are approaching each other to within a certain distance. When this state is detected, the inkjet recording device 600 controls the system to adjust the solvent concentration of the ink 68A by supplying solvent 69A from the solvent container 33 to the ink container 31, because the recovered solvent 69B contained in the recovery container 73 cannot be properly supplied to the ink container 31.

[0095] Next, the liquid draining operation of the recovery container 73 of the inkjet recording device 600 according to Example 1 will be explained with reference to Figure 17. Figure 17 is a cross-sectional view of the head cleaning unit 4 when the liquid draining operation of the recovery container 73 is being performed. In the inkjet recording device 600, if the amount of recovered solvent 69B in the recovery container 73 becomes large and the liquid level sensor 76 detects the maximum liquid level detection unit 76A, the head cleaning process cannot be performed. In that case, if the head cleaning process is to be performed, it is necessary to reduce the amount of recovered solvent 69B in the recovery container 73 so that the maximum liquid level detection unit 76A is not detected. One method of doing this is to replenish the recovered solvent 69B from the recovery container 73 to the ink container 31, but it may take time for the amount of recovered solvent 69B to decrease. Another method is to drain the recovered solvent 69B from the recovery container 73.

[0096] In Figure 17, the discharge fitting B87 is detached from the tube fixing part 71G of the washing tank 71, and the tube 86 is positioned so that the discharge fitting B87 is below the recovery container 73. This allows the recovered solvent 69B contained in the recovery container 73 to flow out of the head washing unit 4.

[0097] <Effects of Example 1> As described above, according to Embodiment 1 of the present invention, the print head can be easily cleaned simply by inserting it into the head cleaning unit set, and the solvent 69A used for head cleaning can be collected and stored in the recovery container 73. Furthermore, the recovered solvent 69B can be reused to adjust the concentration of the ink 68A stored in the ink container 31. Therefore, the inkjet recording device 600 reduces the effort required to dispose of the recovered solvent 69B during head cleaning and reduces the amount of recovered solvent 69B to be discarded, thereby providing an inkjet recording device 600 that can reduce the running costs for the customer.

[0098] Example 2 The inkjet recording device 700 in Embodiment 2 of the present invention will be described with reference to Figures 18 and 19. Note that the parts common to Embodiment 1 will be omitted from the description, and the description will mainly focus on the parts that differ from Embodiment 1.

[0099] <Exterior Configuration> Figure 18 is an external perspective view of the inkjet recording device 700 in this embodiment, with a portion of the main body 1 shown in cross-section to reveal the inside. Figure 19 is a perspective view of the inkjet recording device 700 in this embodiment with the print head 2 attached to the cleaning tank 271.

[0100] First, as shown in Figure 18(a), the inkjet recording device 700 comprises a main body 201 and a print head 2 connected to the main body 1 by a conduit (for the print head) 5. The main body 201 has a maintenance door 9 on its front, and inside the maintenance door 9 is a container base 95 assembled at the bottom, and on top of the container base 95 are circulating system components such as an auxiliary ink container 32, a solvent container 33, a head cleaning unit 204, and a drive unit 203. The maintenance door 9 has a maintenance door handle 94 assembled at the top center, making it easy for workers to open and close the maintenance door 9. By opening the maintenance door 9, the inkjet recording device 700 can perform routine maintenance tasks such as refilling the auxiliary ink container 32 with ink 68A, refilling the solvent container 33 with solvent 39A, and cleaning the print head 2 with solvent 69A using the head cleaning unit 204.

[0101] The inkjet recording device 700 shown in Figure 18(b) has its maintenance door 9 open and the head cleaning unit 204 pulled out towards the front. The maintenance door 9 can be opened to an angle of 90°, and a rail 296 is formed on the back surface of the maintenance door 9. The head cleaning unit 204 can be pulled out towards the front along the rail 296. The head cleaning unit 204 is integrated with the drive unit 203 in order to simplify the components.

[0102] Next, with reference to Figure 19, the state in which the print head 2 is set in the head cleaning unit 204 in the inkjet recording device 700 will be described. The print head 2 is inserted from the tip of the print head 2 into the print head insertion section 72A of the head cleaning unit 204. In this embodiment, the inkjet recording device 700 can clean the print head 2 by setting the print head 2 in the head cleaning unit 204 in this manner.

[0103] <Route Configuration> Figure 20 shows the overall path configuration of the inkjet recording device 700 in this embodiment. Note that the explanation of parts common to Embodiment 1 will be omitted, and the explanation will mainly focus on the parts that differ from Embodiment 1.

[0104] The head cleaning paths 809, 821, and 841 of the inkjet recording device 700 in this embodiment will be described. In Figure 20, the pump (for solvent) 37 is connected to path 821 via branch path 903, and path 821 is connected to path 841 via a connecting part (for head cleaning) 59A and a fitting (for head cleaning) 260A for relaying to the drive unit 203 incorporated inside the main body 201. A solenoid valve (for nozzle cleaning) 55 for opening and closing the flow path is located in path 841, and the solenoid valve (for nozzle cleaning) 55 is connected to a filter (for head cleaning) 42 for removing foreign matter mixed in the solvent 69A.

[0105] The filter (for head cleaning) 42 is connected to the filter (for cleaning nozzle) 43 to remove any foreign matter that may initially enter the path 841. The filter (for cleaning nozzle) 43 is then connected to the cleaning nozzle 74 located inside the cleaning tank 71 of the head cleaning unit 204. The space inside the cleaning tank 71 is configured to communicate with a recovery container 73 located at the bottom.

[0106] Next, the solvent reuse paths 842, 824, and 807 of the inkjet recording device 700 in this embodiment will be described. In Figure 20, the head cleaning unit 204 is equipped with a recovery container 73 that holds the recovered solvent 69B that has flowed in by gravity after being used for head cleaning. The recovery container 73 is fitted with a filter (for the recovery container) 77 to prevent foreign matter mixed in during head cleaning from flowing into path 842. The recovery container 73 is connected to path 842 in the portion immersed in the recovered solvent 69B. Path 842 has a drive unit 203 inside the main body 201, and a filter (solvent reuse) 44 is positioned therein to prevent fine foreign matter contained in the recovered solvent 69B from mixing with the ink 68A.

[0107] The filter (solvent reuse) 44 is connected to a solenoid valve (solvent reuse) 57 for opening and closing the flow path. The path 842, where the solenoid valve (solvent reuse) 57 is located, is connected to the drive unit 203 via a connecting unit (solvent reuse) 59B and a fitting (solvent reuse) 260B to the path 824. The path 824 is connected to a pump (for circulation) 36 located in the path 807 via a confluence path 902. This configuration allows the recovered solvent 69B held in the recovery container 73 to be replenished to the ink container 31 and reused for adjusting the ink concentration.

[0108] Next, the head drying air path 843 of the inkjet recording device 700 in this embodiment will be described. In Figure 20, the drive unit 203 housed in the main body 201 is equipped with a pump (for supplying drying air) 38 used for drawing in and pumping air, and the pump (for supplying drying air) 38 forms an air intake port that communicates with the inside of the main body 201. The pump (for supplying drying air) 38 is connected to an air nozzle 75 provided inside the cleaning tank 71 of the head cleaning unit 204.

[0109] <Effects of Example 2> As described above, according to Embodiment 2 of the present invention, by arranging the cleaning tank 271 and the recovery container 273 inside the main body 201, the inkjet recording device 700 is equipped with a head cleaning function and a recovery solvent 69B reuse function, similar to Embodiment 1, and also provides an inkjet recording device 700 with improved ease of installation.

[0110] <<Other Examples>> Although Examples 1 and 2 have been described above, the present invention is not limited to Example 1, and various modifications are included. Furthermore, Examples 1 and 2 described above are detailed in order to explain the present invention in an easy-to-understand manner, and are not necessarily limited to having all the configurations described. [Explanation of symbols]

[0111] 1...Main unit, 2...Print head, 3...Drive unit, 4...Head cleaning unit, 5...Conduit, 6...Conduit, 8...Operation display unit, 9...Maintenance door, 10...Control unit, 11...Belt conveyor, 12A...Print target (before printing), 12B...Print target (after printing), 13...Print head fixing bracket, 14...Conveyor column, 16...Head base, 17...Protective cover, 17A...Print opening, 17B...Cleaning opening, 17C...Lower end of opening, 17D...Seat surface, 17E...Upper end of opening, 18...Protective cover door, 18A...Opening / closing support part, 18B...Slotted hole part, 18C...Lower end of door, 18D...Upper end of door, 19...Door closing lever 20...Pin, 21...Nozzle, 21A...Discharge port, 23...Charging electrode, 24...Declining electrode, 25...Gutter, 25A...Gutter discharge port, 26...Switching valve, 27...Temperature sensor A, 28...Proximity sensor A, 29...Magnet A, 30...Magnet B, 31...Ink container, 31A...Liquid level sensor, 32...Auxiliary ink container, 33...Solvent container, 34...Pump (for supply), 35...Pump (for recovery), 36...Pump (for circulation), 37...Pump (for solvent), 38...Pump (for dry air supply), 39...Filter (for supply), 40...Filter (for recovery), 41...Filter (for nozzle cleaning), 42...Fi 43…Filter (for cleaning nozzles), 44…Filter (solvent reuse), 45…Viscometer, 46…Pressure regulating valve, 47…Pressure sensor, 48…Charge sensor (detection means), 49…Solenoid valve (for supply), 50…Solenoid valve (for recovery), 51…Solenoid valve (for circulation), 52…Solenoid valve (for viscosity measurement), 53…Solenoid valve (for solvent replenishment), 54…Solenoid valve (for ink replenishment), 55…Solenoid valve (for nozzle cleaning), 56…Solenoid valve (for head cleaning), 57…Solenoid valve (solvent reuse), 58…Storage area, 59A…Connection part (for head cleaning), 59B…Connection part (solvent reuse), 60A…Connection Hand (for head cleaning), 60B... Fitting (solvent reuse), 61A... Sealing plug (for solvent supply), 61B... Sealing plug (solvent reuse), 63... Start button, 64... Stop button, 65... Display unit, 68A... Ink, 68B... Ink particles, 69A... Solvent, 69B... Recovered solvent, 69C... Liquid level, 69D... Liquid level, 71... Cleaning tank, 71A... Side wall, 71B... Print head support, 71C... Conical inner bottom, 71D... Liquid outlet, 71E... Sensor mounting part, 71F... Communication hole, 71G... Tube fixing part, 72... Lid block, 72A... Print head insertion part, 72B... Liquid flow path, 72C... Air flow path,72D...Door support section, 73...Recovery container, 73A...Liquid storage section, 73B...Liquid reservoir section, 73C...Solvent reuse channel, 73D...Liquid discharge channel, 74...Washing nozzle, 74A...Liquid channel section, 74B...Liquid discharge hole A section, 74C...Liquid discharge hole B section, 74D...Liquid discharge hole C section, 75...Air nozzle, 75A...Air channel section, 75B...Air discharge hole A section, 75C...Air discharge hole B section, 76...Liquid volume sensor, 76A...Maximum liquid volume detection section, 76B...Minimum liquid volume detection section, 76C...Float Part, 77...Filter (for recovery container), 78...Liquid fitting, 79...Air fitting, 80...Reusable fitting, 81...Discharge fitting A, 82...Lid hinge, 83...Lid member, 83A...Lid member projection, 84...Temperature sensor B, 85...Cover, 86...Tube, 87...Discharge fitting B, 88...Seal member, 89...Nut, 90...Proximity sensor B, 91...Fixing jig (for main body), 92...Fixing jig (for conveyor), 93...Fixing jig fitting part, 94...Maintenance door handle, 201...Main Body, 203...Drive unit, 204...Head cleaning unit, 260A...Coupling (for head cleaning), 260B...Coupling (solvent reuse), 271...Cleaning tank, 273...Recovery container, 295...Container base, 296...Rail, 600...Inkjet recording device, 700...Inkjet recording device, 801~803...Path (for supply), 804...Path (for recovery), 805...Path (for exhaust), 806~807...Path (for circulation), 808...Path (for viscosity measurement), 8 09... Route (for solvent supply), 810... Route (for solvent replenishment), 811... Route (for ink replenishment), 812... Route (for nozzle cleaning), 821~822... Route (for head cleaning), 823~824... Route (for solvent reuse), 825... Route (for drying air), 841... Route (for head cleaning), 842... Route (for solvent reuse), 843... Route (for drying air), 901... Confluence route (for supply), 902... Confluence route (for circulation), 903... Branch route (for solvent),

Claims

[Claim 1] An inkjet recording device comprising a main body and a print head, The main body contains an ink container that holds ink for printing on the object to be printed and supplies ink to the print head. The print head includes a nozzle connected to the ink container from which pressurized ink is discharged, 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 collecting ink that is not used for printing. The head cleaning unit is further configured to be attachable to the side wall of the main body, The main body is, The print head has a solvent container for supplying solvent, With the print head set in the head cleaning unit, the system controls the unit to clean the print head using the solvent supplied from the solvent container. The main body is, An inkjet recording device that, with the print head set in the head cleaning unit, supplies ink from the ink container to the print head, ejects the ink from the nozzle, and controls the device to recover the ink ejected from the nozzle from the gutter.

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