Inkjet recording device and recording apparatus

Abstract

To provide an ink jet recording device which facilitates attachment and detachment of a container, and is effective in preventing liquid leakage.SOLUTION: An ink jet recording device includes a print head, an ink container, and a control part which supplies ink in the ink container to the print head and controls printing operation of the print head, and is provided with a cleaning unit. The cleaning unit includes a cleaning tank, a cleaning nozzle, and a recovery container which recovers a cleaning liquid, and is provided with a liquid level detection device which detects a liquid level in the recovery container. The liquid level detection device includes a float which moves in response to a liquid level and a holder which holds the float in the recovery container. A sensor which outputs a liquid level detection signal when the float approaches is arranged on an outside of the recovery container. With this structure, the recovery container can be easily detached and attached. Furthermore, it can be determined whether or not the recovery container is attached to the cleaning unit.SELECTED DRAWING: Figure 4

Description

[Technical field]

[0001] The present invention relates to an inkjet recording apparatus, a cleaning unit for the inkjet recording apparatus, and a liquid level detection device. [Background technology]

[0002] As a technique related to this technical field, the technique described in WO2015 / 114814 (Patent Document 1) is known. Patent Document 1 (WO2015 / 114814) discloses an inkjet recording device that is provided with a liquid level detection device that detects the liquid level in an auxiliary ink container that is filled with ink, and that is configured to replace the ink cartridge and fill the auxiliary ink container with ink when the ink in the auxiliary ink container falls below a predetermined level using a liquid level detection signal detected by the liquid level detection device. The auxiliary ink container that stores ink is prepared to fill an ink container (main ink container) that stores ink to be supplied to the print head with a required amount of ink. Patent Document 1 discloses two types of liquid level detection devices. That is, the first liquid level detection device is configured to install multiple electrodes (specifically, four) in the container, connect electric wires to each electrode, and extract a liquid level detection signal to the outside of the container through the electric wires (see the description in paragraphs 0034 to 0038 of Patent Document 1).

[0003] Another liquid level detection device has a stopper at a position inside the container where the ink volume (liquid level) corresponds to a standard level, and is equipped with float A which detects when the ink has reached the standard level, and float B which detects when the ink is about to run out, and is configured so that the liquid level detection signals detected using each of these floats are output to the outside of the container via electric wires (see paragraphs 0072 to 0075). [Prior art documents] [Patent documents]

[0004] [Patent Document 1] WO2015 / 114814 publication Summary of the Invention [Problem to be solved by the invention]

[0005] In the technology of Patent Document 1, in both liquid level detection devices, in order to extract (output) a liquid level detection signal to the outside of the container, a detection unit disposed in the container detects the liquid level detection signal and outputs it to the outside of the container via an electric wire. Therefore, if the container is to be removed, it is necessary to first remove the electric wire and then remove the container, which makes the container removal work complicated. In addition, when attaching the container, it is necessary to attach the container in a predetermined position with an electrode rod, a float, etc., inserted in the container, which makes the work even more complicated. In addition, problems arise in these operations in terms of achieving a stable electrical connection (preventing short circuits and maintaining good electrical contact).

[0006] In an inkjet recording device, a print head is essential for printing. This print head involves the extremely high speed flight of ink, so it is inevitable that the print head will become dirty due to the scattering of ink during use, and it becomes necessary to clean the print head from time to time.

[0007] However, performing cleaning work manually is time-consuming, and it is unclear whether cleaning is being performed reliably when cleaning is done manually. For this reason, recently, consideration has been given to providing inkjet recording devices with cleaning units that automatically clean the print head. This cleaning unit includes a cleaning tank in which the print head is set (housed) for cleaning, a cleaning nozzle that sprays cleaning liquid toward the print head set in the cleaning tank to clean it, and a recovery container that is provided at the bottom of the cleaning tank to collect the cleaning liquid after cleaning.

[0008] In such a cleaning unit, if cleaning is performed several times and the cleaning liquid is left as it is, the cleaning liquid will overflow from the collection container and flow out. Therefore, a liquid level detection device is provided to detect the liquid level of the cleaning liquid in the collection container, and a detection signal from the liquid level detection device is used to notify an operator that the cleaning liquid has reached a certain amount or more, and the operator removes the collection container and performs the work of discharging the cleaning liquid in the container. Then, the empty collection container is attached again to the bottom of the cleaning tank. However, since such removal and installation work of the collection container (removal and installation work) is performed quite frequently, if a liquid level detection device such as that described in the above-mentioned Patent Document 1 is used, the removal and installation work of the container becomes very complicated and is not practical. Also, in a cleaning unit, if a cleaning work is performed with the collection container accidentally removed from the cleaning tank, the cleaning liquid after cleaning will flow out from the bottom of the cleaning tank and contaminate the surroundings. Therefore, a separate device is usually required to detect whether the container is attached or not.

[0009] Therefore, an object of the present invention is to provide an inkjet recording device, a cleaning unit for an inkjet recording device, and a liquid level detection device that are easy to remove and install a container and are effective in preventing liquid from leaking out of the container. [Means for solving the problem]

[0010] In order to achieve the above-mentioned object, one example of the present invention is an inkjet recording device having a print head for printing, an ink container, a path for supplying ink in the ink container to the print head and recovering the ink not used for printing back to the ink container, and a control unit for controlling the supply of ink to the print head and the printing operation of the print head, the inkjet recording device further comprising: a cleaning tank having a space capable of accommodating the print head and having a liquid outlet at a lower portion; and a cleaning nozzle for spraying cleaning liquid towards the print head accommodated in the cleaning tank to clean it. The inkjet recording device is provided with a cleaning unit having a collection container for collecting the cleaning liquid flowing out from the liquid outlet of the cleaning tank, and a first liquid level detection device for detecting the liquid level of the cleaning liquid in the collection container, the first liquid level detection device having a first float within the collection container that moves in response to the liquid level and a first holder for holding the first float, and a first sensor installed outside the collection container that outputs the liquid level detection signal when the first float approaches, and the control unit determines the installation status of the collection container from the liquid level detection signal.

[0011] Another example of the present invention is a cleaning unit of an inkjet recording device having a print head that prints with ink, the cleaning unit comprising: a cleaning tank having a space capable of accommodating the print head and a liquid outlet portion; a cleaning nozzle that sprays cleaning liquid toward the print head accommodated in the cleaning tank to clean it; a recovery container that collects the cleaning liquid after cleaning that flows out of the liquid outlet portion of the cleaning tank; and a liquid level detection device that outputs a liquid level detection signal of the cleaning liquid in the recovery container, the liquid level detection device comprising: a float that moves in the recovery container in response to the liquid level, and a holder to hold the float; and a sensor that outputs the liquid level detection signal when the float approaches the recovery container, the liquid level detection signal being installed outside the recovery container, and the installation status of the recovery container being determined from the liquid level detection signal.

[0012] Another example of the present invention is a liquid level detection device for detecting the level of a liquid in a container, the liquid level detection device comprising: a float that moves in the collection container in response to the liquid level; and a holder that holds the float; a sensor that outputs a liquid level detection signal when the float approaches the collection container; and a liquid level detection signal that is used to determine the installation status of the collection container. Effect of the Invention

[0013] According to the present invention, it is possible to provide an inkjet recording device in which a container can be easily removed and attached and which is effective in preventing liquid from leaking out of the container, a cleaning unit for the inkjet recording device, and a liquid level detection device. [Brief description of the drawings]

[0014] [Figure 1] FIG. 1 is a diagram showing a usage state of an inkjet recording apparatus according to an embodiment of the present invention. [Diagram 2] FIG. 2 is a schematic cross-sectional view of the main body of an inkjet recording apparatus in the embodiment. [Diagram 3] FIG. 2 is a diagram showing a schematic configuration of a control unit of an inkjet recording apparatus in an embodiment. [Figure 4] FIG. 2 is a diagram showing the overall path configuration of an inkjet recording apparatus in the embodiment. [Diagram 5] FIG. 4 is a configuration diagram of a head cleaning unit in the embodiment. [Figure 6] FIG. 4 is a diagram showing the configuration of a float of the liquid level detection device in the embodiment. [Figure 7] FIG. 2 is an exploded view of a float of the liquid level detection device in the embodiment. [Figure 8] FIG. 4 is a cross-sectional view of the cleaning unit with the print head installed. [Figure 9] 13 is a diagram showing a state in which it is detected that the collection container in the cleaning unit is almost full of cleaning liquid; FIG. [Figure 10]FIG. 13 is a diagram showing the cleaning unit with the collection container removed. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0015] Specific examples of the present invention will now be described with reference to Figures 1 to 10. However, the present invention is not limited to the examples described below. In addition, in the following drawings, the same devices are given the same numbers (reference characters), and the description of devices that have already been described may be omitted.

[0016] (Use state of the inkjet recording device in the embodiment) First, a description will be given of the basic configuration and usage state of an inkjet recording apparatus 100 in an embodiment of the present invention. Fig. 1 is a diagram showing the usage state of an inkjet recording apparatus 100 in this embodiment.

[0017] First, as shown in FIG. 1, the inkjet recording device 100 of this embodiment includes a main body 1, a print head 2 connected to the main body 1 via a conduit 5 (for the print head), and a cleaning unit 3 connected to the main body 1 by a conduit 6 for the cleaning unit.

[0018] The inkjet recording device 100 is installed, for example, on a production line in a factory where food and beverages are produced. The main body 1 has a function of supplying ink for printing to the print head 2 and recovering ink not used by the print head 2. The main body 1 also includes an ink container for storing ink, an auxiliary ink container for refilling the ink container with ink when the ink in the ink container is used for printing and becomes low, and also includes a path for supplying and recovering ink and solvent, and a group of on-off valves (group of solenoid valves) and a group of pumps provided along the path. The main body 1 also includes a control unit 7 (not shown in FIG. 1) for controlling printing by the print head, and for controlling the supply and recovery of ink and solvent, and an operation display unit 8 for giving operation commands to the control unit 7 and displaying various states of the inkjet recording device transmitted from the control unit 7. The main body 1 is installed in a place where the space required for periodic maintenance work can be secured.

[0019] The print head 2 is fixed to a print head fixing bracket 13 installed near the belt conveyor 11, and is installed close to print objects 12A, 12B fed on the belt conveyor 11 in the direction of arrow X in order to print on them. Note that print object 12A indicates the print object before printing, and print object 12B indicates the print object after printing. The print head 2 is also equipped with parts such as a nozzle, charging electrode, deflection electrode, etc. (not shown in FIG. 1) on a head base 16. A protective cover 17 is also attached to the print head 2 in order to protect these parts.

[0020] The cleaning unit 3 provided for cleaning the print head 2 is attached near the belt conveyor 11 by a fixing jig 92 and a fitting portion 93 for fitting the fixing jig 92. The cleaning unit 3 includes a cleaning tank 71, a cleaning nozzle (not shown in FIG. 1) for cleaning the print head 2 set in the cleaning tank, and a recovery container 4 for recovering the cleaning liquid. The conduit 6 is a conduit for supplying the cleaning liquid from the main body 1 to the cleaning unit 3.

[0021] (Main body configuration) Next, a description will be given of the layout configuration of the main body 1 of the inkjet recording apparatus 100 in this embodiment. Fig. 2 is a diagram showing a cross section of the main body 1 of the inkjet recording apparatus in this embodiment. In FIG. 2, the container unit 510 is a portion that houses the container group (ink container 31, auxiliary ink container 32, solvent container 33). The flow path board 520 is a board portion that compiles flow paths (paths) for supplying and recovering ink and supplying and recovering solvent. The pump unit 530 is a portion that mounts the pump group (pumps 34-35, 37, 38) that are provided along the paths. The solenoid valve unit 540 is a portion that mounts the solenoid valve group (solenoid valves 49, 50, 53-56) that are provided along the paths to open and close the flow paths. The specific configurations of the pump group and the solenoid valve group (see FIG. 4) will be described later.

[0022] A control unit 7 is disposed on the top of the main body 1, and the control unit 7 controls the entire inkjet recording apparatus 100. The specific configuration of the control unit 7 will be described later. An operation display unit 8 is provided on the upper front surface of the main body 1. In this embodiment, the operation display unit 8 is configured by incorporating an operation touch panel and a display device into one body. Of course, the operation display unit may be configured by providing the operation unit and the display device separately. A power supply 70 for use in the inkjet recording apparatus 100 is also provided on the top of the main body 1.

[0023] (Control Unit Configuration) Next, the configuration of the control unit 7 in the embodiment of the present invention will be described below. 3, the control unit 7 has a microprocessing unit (MPU) 701, a read-only memory (ROM) 702 that stores programs for the operation of the MPU 701 and data and information necessary for the operation, and a random access memory (RAM) 703 that stores data on print contents, data necessary for control, input signals, etc. The control unit 7 also has a print head control circuit 704 that controls the charging voltage, deflection voltage, and various timings for driving the print head 2 to print, a pump control circuit 705 that controls the driving and stopping of the pumps, and a valve control circuit 706 that controls the opening and closing of the solenoid valves. The MPU 701 controls the print head control circuit 704, pump control circuit 705, and valve control circuit 706 to control the entire inkjet recording apparatus.

[0024] Furthermore, the control unit 7 in this embodiment has a liquid level detection signal input unit 707 that inputs a liquid level detection signal from each liquid level detection device. The liquid level detection signal input to the control unit 7 via this liquid level detection signal input unit 707 is temporarily stored in the RAM 702 and used for calculation, judgment, control, etc. by the MPU. The MPU 701 recognizes that the liquid level in the container has reached a predetermined position based on this liquid level detection signal, and further displays a warning regarding a cleaning operation, etc. on the operation display unit 8. Also, using this liquid level detection signal, a control signal for controlling the liquid level to a predetermined value is calculated, and the associated pumps and solenoid valves are controlled via the pump control circuit 705 and the valve control circuit 706.

[0025] (Overall route configuration) Next, a description will be given of the path configuration of the ink jet recording apparatus 100 according to the embodiment of the present invention. Fig. 4 is a diagram showing the overall path configuration of the inkjet recording device in this embodiment. In Fig. 4, the inkjet recording device 100 comprises a main body 1, a print head 2, a head cleaning unit 3, and conduits 5 and 6 connecting them. The main body 1 and the print head 2 are connected by the conduit 5, and the main body 1 and the head cleaning unit 3 are connected by the conduit 6.

[0026] [Ink supply to print head] First, a description will be given of the ink supply paths (paths 801 to 803) that supply ink from the main body 1 to the print head 2. In Fig. 4, the main body 1 is provided with an ink container 31 that holds circulating ink 68A. The ink container 31 is connected to a path 801 at a portion immersed in the ink 68A, and a viscosity measuring device 45 and an electromagnetic valve 49 for opening and closing the path for ink supply are provided midway along the path 801. The viscosity measuring device 45 is provided to measure the viscosity of the ink, and the viscosity is input to the control unit 7. Specifically, the viscosity is input and stored in the RAM 703. The control unit 7 executes control based on this viscosity detection signal to maintain the viscosity of the ink 68A at a predetermined value or within a predetermined range.

[0027] Furthermore, the path 801 is connected to the ink supply pump 34, which is installed in the path 802 and used for sucking and pumping the ink 68A, via a junction path 901. The output side of the pump 34 is connected to a filter 39 (for ink supply) that removes foreign matter mixed in the ink 68A.

[0028] The filter 39 is connected to a pressure regulating valve 46 that adjusts the pressure of the ink 68A pumped from the pump 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 ink 68A supplied to the nozzles 21. A path 802 in which the pressure sensor 47 is arranged passes through the conduit 5 and is connected to the print head 2. More specifically, it is connected to a switching valve 26 that controls whether or not to supply ink 68A to the nozzles 21.

[0029] The switching valve 26 is connected to the nozzle 21 having an outlet for ejecting the ink 68A via a path 803. The switching valve 26 is a three-way solenoid valve, and an ink supply path 802 and a nozzle cleaning path 812 are connected to the switching valve 26, so that the supply of the ink 68A and the solvent 69A to the nozzle 21 can be switched. In the straight direction of the outlet of the nozzle 21, there are arranged a charging electrode 23 for adding a predetermined amount of charge to the ink particles 68B atomized by the nozzle 21 (adding an amount of charge corresponding to the printing content), a deflection electrode 24 for deflecting the ink particles 68B used for printing in accordance with the amount of charge, and a gutter 25 for capturing the ink particles 68B that are not used for printing and fly straight without being charged or deflected. Printing is performed by landing the ink particles 68B deflected by the deflection electrode 24 on a print target.

[0030] [Recovering ink from the print head] Next, the ink recovery path (path 804) of the inkjet recording device 100 in this embodiment will be described. In FIG. 4, the gutter 25 is connected to the path 804. The path 804 passes through the conduit 5 and is connected to a filter 40 (for ink recovery) that removes foreign matter mixed in the ink arranged in the main body 1, and the filter 40 is connected to an electromagnetic valve 50 (for ink recovery) that opens and closes the path 804. Furthermore, the electromagnetic valve 50 is connected to a pump 35 (for ink recovery) that sucks the ink particles 68B captured by the gutter 25, and the pump 35 is connected to the ink container 31. The ink container 31 is connected to the path 805 in an upper space that does not contact the ink 68A, and the path 805 is configured to communicate with the outside of the main body 1. In this configuration, the control unit 7 opens the electromagnetic valve 50 and executes control to drive the pump 35, so that the ink particles 68B captured by the gutter 25 are recovered into the ink container 31 through these.

[0031] [Solvent supply route] Next, the solvent supply path (paths 809-810) of the inkjet recording device 100 in this embodiment will be described. In FIG. 4, the main body 1 is provided with a solvent container 33 that holds (contains) a solvent 69A to be used for supplying the solvent to the ink container 31 and for cleaning the nozzle and the head. The solvent container 33 is connected to a path 809 at a portion immersed in the solvent 69A, and a pump 37 used for sucking and pumping the solvent is disposed in the path 809. The pump 37 is connected to a branch path 903 to change the supply destination of the solvent 69A depending on the purpose. The branch path 903 is connected to an electromagnetic valve 53 for opening and closing a flow path disposed in a path 810 in the solvent supply path, and the electromagnetic valve 53 is configured to be connected to the ink container 31 by a path.

[0032] In this configuration, the solvent 69A can be supplied to the ink container 31 by opening the solenoid valve 53 and driving the pump 37. The supply (replenishment) of the solvent to the ink container 31 is performed in order to bring the ink viscosity within a predetermined value range when the ink viscosity detected by the viscosity measuring device 45 becomes higher than a predetermined value. Specifically, when the control unit 7 determines that the ink viscosity input from the viscosity measuring device 45 has become higher than a viscosity appropriate for printing, it opens the solenoid valve 53 and drives the pump 37 to supply the solvent 69A in the solvent container 33 to the ink container 31, thereby controlling the viscosity of the ink 68A to be appropriate.

[0033] In this embodiment, the solvent container 33 is provided with a liquid level detection device 33A that detects whether the solvent 69A in the solvent container 33 is within an appropriate range. The liquid level detection device 33A has a float 331 that moves up and down in response to the liquid level fluctuation inside the solvent container 33, and a holder 332 that holds the float 331. The holder 332 prevents the float 331 from moving other than up and down. Stoppers (shown as triangular shapes in the figure) are provided at the top and bottom positions of the holder 332. Specifically, the holder 332 has stoppers at the positions where the float 331 detects the minimum liquid level and the maximum liquid level, respectively. The sensors 333 and 334 that detect the float 331 are arranged so as to output a liquid level detection signal when the float approaches (comes close to) the stoppers. Here, the two sensors 333 and 334 are attached to a support member 335 on the outside of the solvent container 33. That is, the sensor 333 on the bottom side of the solvent container 33 outputs a liquid level detection signal when the float 331 moves to the lower stopper and approaches it due to a change in the liquid level. The sensor 334 on the upper side of the solvent container 33 outputs a liquid level detection signal when the float 331 moves upward and approaches the upper stopper. Since the sensors 333 and 334 of the liquid level detection device 33A are installed outside the solvent container 33 and the electric wire (not shown) that transmits the liquid level detection signal to the control unit 7 is wired outside the solvent container 33, the installation and removal (removal and installation) of the solvent container 33 becomes easy.

[0034] The sensor 333 outputs a liquid level detection signal when the float 331 moves to a position where it contacts the lower stopper of the holder 332. Moreover, the sensor 334 outputs a liquid level detection signal when the float 331 moves to a position where it contacts the upper stopper of the holder 332. The liquid level detection signals detected by the sensors 333 and 334 are input to the control unit 7. Specifically, the liquid level detection signals are stored in the RAM 703 via the liquid level detection signal input unit 707 of the control unit 7 (see FIG. 3).

[0035] When the control unit 7 (specifically, the MPU 701) uses this liquid level detection signal to determine that the solvent 69A in the solvent container 33 is not within a predetermined liquid level range, it displays the remaining state of the solvent on the operation display unit 8 and displays a warning that the solvent is insufficient. Specifically, the MPU 701 uses the liquid level detection signal stored in the RAM 703 to determine whether the solvent is insufficient or excessive, and when there is a shortage, displays a warning on the screen of the operation display unit 8 that the solvent is insufficient and that the solvent needs to be replenished. This allows the operator to know that the solvent needs to be replenished.

[0036] [Ink supply path] Next, the ink supply path of the inkjet recording device 100 in this embodiment will be described. In FIG. 4, the main body 1 is provided with an auxiliary ink container 32 that holds refill ink 68C. The auxiliary ink container 32 is connected to a path 811 for ink supply at a portion immersed in the ink 68C. The path 811 is connected to an electromagnetic valve 54 that opens and closes the path, and the electromagnetic valve 54 is connected via a junction path 901 to a pump 34 that is installed in a path 802 and is used to suck and pump the ink 68C. The ink 68C in the auxiliary ink container 32 is fed to the print head 2, passes through the nozzle 21 and the gutter 25, and then passes through an ink recovery path consisting of a path 804, an electromagnetic valve 50, and a pump 35, and is replenished to the ink container 31.

[0037] The timing of refilling the ink container 31 with the ink in the auxiliary ink container 32 is determined by utilizing the liquid level detection value of the liquid level detection device 31A that detects the ink level in the ink container 31. In other words, the ink container 31 is provided with the liquid level detection device 31A that detects whether the ink in the ink container 31 has reached a reference liquid level, which is an appropriate amount.

[0038] This liquid level detection device 31A has the same configuration as the above-mentioned liquid level detection device 33A. That is, inside the ink container 31, there is a float 311 that moves up and down in response to the liquid level fluctuation, and a holder 312 that holds the float 311 and suppresses movements other than the up and down movement of the float. As in the previous embodiment, stoppers are provided above and below the holder 312. Also, sensors 313 and 314 of this liquid level detection device 31A are attached to a support member 315 on the outside of the ink container 31. The sensor 313 provided on the lower side of the outside of the ink container 31 outputs a liquid level detection signal when the float 311 approaches the lower stopper of the holder. The sensor 314 provided on the upper side of the outside of the container outputs a liquid level detection signal when the float 311 approaches the upper stopper of the holder 312. Since the sensors 313 and 314 are arranged on the outside of the ink container 31, it is easy to remove and install the ink container 31 for inspection and cleaning. The liquid level detection signals detected by the sensors 313 and 314 are stored in the RAM 703 via a liquid level detection signal input unit 707 of the control unit 7 (see FIG. 3).

[0039] The control unit 7 uses this liquid level detection signal to control the ink in the ink container 31 to a predetermined amount. Specifically, when the ink level in the ink container 31 drops to a level detected by the sensor 313, the supply of ink to the ink container 31 is started. When the control unit 7 inputs a detection signal from the sensor 313 of the liquid level detection device 31A, the control unit 7 starts refilling the ink. That is, the control unit 7 can know from the liquid level detection signal from the sensor 313 that the ink amount (ink level) in the ink container 31 has decreased to a predetermined amount or less, and therefore refills the ink 68C in the auxiliary ink container 32 from the path 811, the path 802, the print head 2, and through the path 804 to the ink container 31. During ink refilling, the solenoid valve 54 provided in the path is opened, the pump 34 is driven, the ink supplied to the print head 2 is captured by the gutter 25, the solenoid valve 50 provided in the path 804 is opened, and the pump 35 is driven. As a result, the ink 68C in the auxiliary ink container 32 is supplied (replenished) to the ink container 31. When the ink level rises due to the ink replenishment and the sensor 314 of the ink level detection device 31A outputs a liquid level detection signal, the control unit 7 ends this ink replenishment operation. The control unit 7 ends the ink replenishment operation by closing the solenoid valve 54 and stopping the pump 34.

[0040] In this embodiment, a liquid level detection device 32A is also provided to detect the ink level in the auxiliary ink container 32. The liquid level detection signal detected by this liquid level detection device 32A is also input to the control unit 7. The control unit 7 receives this liquid level detection signal and is able to know the ink level in the auxiliary ink container 32. The liquid level detection device 32A has the same configuration as the other liquid level detection devices (31A, 32A) already described. That is, the liquid level detection device 32A has a float 321 that moves up and down in response to the liquid level fluctuation inside the auxiliary ink container 32, and a holder 322 that suppresses the movement of the float 321 other than the up and down movement. Stoppers are provided above and below the holder 322. In addition, the liquid level detection device 32A has sensors 323 and 324 attached to a support member 325 on the outside of the auxiliary ink container 32. The sensor 323 outputs a liquid level detection signal when the float 321 approaches the lower stopper. The sensor 324 outputs a liquid level detection signal when the float 321 approaches the upper stopper. The liquid level detection signals detected by the sensors 323 and 324 are stored as electric signals in the RAM 703 via the liquid level detection signal input unit 707 of the control unit 7 (see FIG. 3).

[0041] The control unit 7 can know from this liquid level detection signal that the ink 68C in the auxiliary ink container 32 has decreased to a level outside the predetermined range, and can implement control to replenish the auxiliary ink, or display a warning on the operation display unit 8 to the effect that the auxiliary ink container 32 needs to be replenished with ink.

[0042] [Nozzle cleaning] Next, the nozzle cleaning paths (paths 809 and 812) will be described. In FIG. 4, pump 37 disposed in path 809 is connected to path 812 via branch path 903. Path 812 is connected to solenoid valve 55 (for nozzle cleaning) for opening and closing the flow path. And solenoid valve 55 is connected to filter 41 (for nozzle cleaning) for removing foreign matter mixed in solvent 69A. Filter 41 is provided in print head 2 via path 812 passing through conduit 5, and is configured to be connected to switching valve 26 for controlling whether or not solvent 69A for cleaning is sent to nozzle 21.

[0043] [Cleaning unit] Next, the basic configuration of the cleaning unit 3 of the inkjet recording apparatus 100 in this embodiment will be described. In FIG. 4, the cleaning unit 3 for cleaning the print head 2 includes a cleaning tank 71 having an opening at the top and a storage space for inserting (setting) the print head 2, a cleaning nozzle 72 for spraying cleaning liquid to clean the print head 2 set in the cleaning tank 71, an air nozzle 73 for spraying dry air to dry the print head 2 after cleaning, and a recovery container 4 attached to the bottom of the cleaning tank 71 for recovering the cleaning liquid 69B that flows out (flows down) from the opening at the bottom of the cleaning tank. In this embodiment, the cleaning liquid used in the cleaning unit 3 is a solvent 69A held in a solvent container 33. Therefore, the immersed portion of the solvent 69A in the solvent container 33 is connected to a path 809, and the pump 37 provided in the middle of the path 809 is connected to a path 821 via a branch path 903. The path 821 is connected to the cleaning nozzle 72 of the cleaning unit 3. A solenoid valve 56 for opening and closing the flow path is arranged in the path 822. With this configuration, the control unit 7 can supply the solvent 69A in the solvent container 33 as a "cleaning liquid" to the cleaning nozzle 72 in the head cleaning unit 3 by controlling the solenoid valve 56 to open and the pump 37 to drive the pump 37. The cleaning liquid may be supplied from a cleaning liquid supply device provided separately from the solvent in the solvent container of the main body 1.

[0044] After the print head has been washed, air can be sprayed from air nozzle 73 to dry print head 2. Air nozzle 73 is connected to path 825, and air can be sprayed into cleaning tank 71 by driving pump 38 provided in path 825. Main body 1 and cleaning unit are connected by conduit 6. Recovery container 4 is provided to store cleaning liquid 69B after cleaning, and when the cleaning liquid 69B in the container reaches a certain liquid level or higher, recovery container 4 is removed and cleaning liquid 69B is discharged. Once empty, recovery container 4 is attached to the bottom of cleaning tank 71 again to store cleaning liquid 69B.

[0045] In this embodiment, a liquid level detection device 4A is provided in the collection container 4 of the cleaning unit 3. The liquid level detection device 4A includes a float 74 that can move up and down in the collection container 4 according to the liquid level, and a holder 75 that holds the float 74. A sensor 76 is provided on the outside of the collection container 4, which outputs a liquid level detection signal when the float 74 moves up and down and approaches the collection container 4. Here, the sensor 76 and the electric wire 76A that transmits the liquid level detection signal to the control unit 7 are provided outside the collection container 4, so they do not interfere with the removal or installation of the collection container 4.

[0046] Incidentally, the more sensors used for liquid level detection, the more precisely the liquid level can be detected. However, the more sensors there are, the more expensive the liquid level detection device becomes. For this reason, in this embodiment, an effort is made to reduce the number of sensors in the liquid level detection device 4A used in the recovery container. That is, the liquid level detection devices 31A, 32A, and 33A are configured with two sensors, one above and one below. In contrast, the liquid level detection device 4A is provided with only one sensor 76.

[0047] The liquid level detection device 4A has a stopper 75A at the middle position of the holder 75, and limits the range of movement of the float 74 in the vertical direction so that it can only move upward from the middle position. The sensor 76 is disposed so as to output a liquid level detection signal when the float 74 approaches the stopper 75A.

[0048] Here, the position where the stopper 75A is provided in the holder 75 is the middle position between the top and bottom (a position below the liquid level for detecting the maximum capacity of the container and a position above the position when there is no liquid in the container). The installation position of the stopper 75A is determined in consideration of the frequency of removing the container and discharging the cleaning liquid 69B in the container, and is determined to be a liquid level position where the risk of the liquid in the container immediately spilling out to the outside in the current operating state is considered to be small. Preferably, the position of the stopper 75A is within a range of 50 to 90% of the liquid level position corresponding to the maximum capacity, which is set to 100%. Here, the reason why the stopper 75A is set to 50% is that if it is set lower than that, the sensor 76 will frequently output a liquid level detection signal, and therefore the frequency of removing and attaching the recovery container 4 to discharge the cleaning liquid 69B will increase. Also, the reason why the stopper 75A is set to 90% is to ensure some margin of time, since when the control unit 7 issues a warning to the operation display unit 8, if the operator is a little late in noticing the tendency, the cleaning liquid 69B may spill out.

[0049] In such a configuration of the liquid level detection device 4A, the float 74 does not move when the liquid level (cleaning liquid 69B) in the collection container 4 is still low and is below the position of the stopper 75A. Therefore, the sensor 76 continues to output a liquid level detection signal during the period when the float 74 does not move (in other words, during the period when the cleaning liquid 69B in the collection container 4 is low). Then, when the liquid level of the cleaning liquid 69B in the collection container 4 rises above the position of the stopper 75A and the float 74 moves upward, the sensor 76 stops outputting the liquid level detection signal. The liquid level detection signal by the sensor 76 is input to the control unit 7. Specifically, it is stored in the RAM 703 via the liquid level detection signal input unit 707 of the control unit 7 (see FIG. 3).

[0050] While the liquid level detection device continues to output the liquid level detection signal, the control unit 7 can determine that the liquid (cleaning liquid 69B) in the collection container 4 is low (in other words, the collection container can still contain a sufficient amount of cleaning liquid 69B), and when the output of the liquid level detection signal is lost, the control unit 7 can determine that the collection container is almost full of cleaning liquid 69B (in other words, the collection container cannot contain the cleaning liquid 69B). In other words, when the liquid level detection signal is interrupted, the control unit 7 can display a warning on the operation display unit 8 instructing the user to drain the cleaning liquid 69B in the collection container 4. In addition, even when the collection container 4 is removed (not present), the liquid level detection signal of the liquid level detection device 4A (sensor 76) disappears because the float 74 is not nearby. Therefore, when the liquid level detection signal is lost, the control unit 7 issues a warning not to perform cleaning (in this embodiment, it is displayed on the operation display unit 8). In this way, by using the liquid level detection signal of the liquid level detection device 4A, it is possible to not only detect the liquid level but also to judge whether the cleaning liquid 69B in the recovery container 4 is likely to accumulate and overflow, or whether the recovery container 4 itself is likely to be removed from the cleaning unit 3 and the liquid is likely to leak out. In addition, it is possible to notify the operator of such a situation. Therefore, the control unit 7 displays an appropriate warning based on this judgment. Alternatively, it is also possible to control the cleaning unit not to perform the cleaning operation.

[0051] In this embodiment, the liquid level detection device 4A installed in the recovery container 4 is provided with a stopper 75A at the middle part of the holder 75, and one sensor 76 is provided to detect the liquid level at that position. However, the liquid level detection device 4A can also be configured in the same manner as the other liquid level detection devices 31A, 32A, and 33A described above. That is, stoppers may be provided at the detection positions for the minimum and maximum liquid levels to be detected, a float may be made movable up and down between the two stoppers according to the fluctuation of the liquid level, and two sensors may be provided outside the container so as to output a liquid level detection signal when the float is located at the upper and lower stoppers. Even with this configuration, when the upper sensor outputs a liquid level detection signal, it can be determined that the container is almost full of liquid and the amount of liquid that can be contained is reduced.

[0052] That is, when the liquid level detection signal of this upper sensor is output, the control unit 7 displays a warning on the operation display unit 8 to inform the operator that the recovery container 4 should be removed and the cleaning liquid 69B should be drained. This enables the operator to remove the recovery container 4 and drain the cleaning liquid 69B therein.

[0053] Furthermore, if the collection container 4 is removed after the upper sensor has operated, the upper and lower sensors will not output a liquid level detection signal. Then, when the collection container 4 is attached thereafter (because there is no liquid in the container), the lower sensor outputs a liquid level detection signal. Therefore, the control unit 7 can determine that there is a high possibility that the collection container 4 has been removed during the period from when the upper sensor operated until when the lower sensor operated (outputs a liquid level detection signal). In that case, the control unit 7 displays a warning as described above. Alternatively, it is possible to control the device so that the operation is not performed during that period.

[0054] When a device (a discharge path, an electromagnetic valve and a pump provided on the path) for discharging the liquid in the collection container 4 to the outside of the container is installed, the associated device (the electromagnetic valve and the pump) can be driven to discharge the cleaning liquid 69B in the collection container 4. In this case, the cleaning liquid 69B may be discharged to the main body 1 side or may be discharged to a separate container.

[0055] (Specific configuration of the cleaning unit) Next, a specific configuration of the cleaning unit 3 will be described with reference to Fig. 5. In the following, description that overlaps with the contents described with reference to Fig. 4 may be omitted. In Figure 5, a lid block 81 is installed on top of the cleaning tank 71. The lid block 81 has a print head insertion section 81A, and this insertion section 81A allows the print head 2 to be inserted. A lid member 83 is provided on the underside of the insertion section 81A, and is normally kept closed by the spring force of a lid hinge 82. This is to prevent dust and other foreign matter from entering the cleaning tank 71. Reference numeral 85 denotes a cover that protects the piping.

[0056] When cleaning the print head 2, the operator inserts the print head 2 into the cleaning tank 71. At this time, the lid member 83, which is closed by the spring force of the lid hinge 82, rotates, and the print head 2 is set in the cleaning tank 71. The cleaning liquid delivered through the path 822 flows into the cleaning nozzle 72 via the liquid coupling 84. The filter 43 is provided midway along the path 822 to remove debris from the cleaning liquid. In this embodiment, the cleaning nozzle 72 has two liquid discharge holes 72A and 72B to spray the cleaning liquid in accordance with the area to be cleaned of the print head 2 to be cleaned.

[0057] In addition, the air nozzle 73 provided for drying the print head 2 after cleaning is also provided with two air discharge holes 73A and 73B. The bottom part of the cleaning tank 71 is provided with a liquid outlet part 71A, and also has an attachment part 71B used when attaching the recovery container 4. The cleaning liquid 69B after cleaning is dropped into the recovery container 4 from this liquid outlet part 71A. The recovery container 4 has an attachment part 77A for attaching to the cleaning tank 71 at the upper end of the container 77. In this embodiment, both the attachment parts 71B and 77A are attached by a screw structure. The recovery container 4 can be removed by an operator by twisting the recovery container 4 in the removal direction (for example, counterclockwise). The recovery container 4 is attached by twisting it in the attachment direction (for example, clockwise). As already mentioned, among the components of the liquid level detection device 4A, the float 74 and the holder 75 are arranged in the recovery container 4. Also, a stopper 75A is formed at the middle position of the holder 75, and prevents the float 74 from moving below the position of the stopper 75A. 75B is an upper stopper that defines the maximum liquid level to be detected. 75C to 75F are openings provided to allow liquid to flow into the holder 75. A sensor 76 of the liquid level detection device 4A is installed on the outside of the recovery container 4, and outputs a liquid level detection signal while the float 74 is at the position of the stopper 75A. The float 74 in this liquid level detection device 4A uses a magnetic float in which a magnet 86 is installed as a detection body, and the sensor 76 is a magnetic proximity sensor that outputs a liquid level detection signal (electrical signal) when the magnet 86 approaches. The detailed operation of this liquid level detection device 4A has already been explained, so it will be omitted.

[0058] As the proximity sensor, it is possible to use proximity sensors other than the magnetic type, for example, other known proximity sensors such as "high frequency transmission type proximity sensors." A high frequency transmission type proximity sensor has a metal provided inside the float, and a high frequency current is applied to a coil as a sensor outside the container to generate a high frequency magnetic field. When the float (metal) approaches this high frequency magnetic field due to a change in the liquid level, an induced current flows in the metal and the oscillation is attenuated (or stopped), and this change in oscillation state is detected by a transmission state detection circuit to operate an output circuit.

[0059] Next, a specific example of the configuration of the "float" of each liquid level detection device used in this embodiment will be described with reference to Figures 6 and 7. Figure 6 shows the configuration of the float, with (A) being a top view, (B) being a front cross-sectional view, and (C) being a view showing the MM cross-section of (B). Figure 7 shows the components of the float in an exploded view.

[0060] 6 and 7, a float of a liquid level detection device, for example, float 74, is composed of a housing 87, a lid 89, a seal member 88 for the lid, a magnet 86, and a magnet fixing part 87B for fixing the magnet 86. The housing 87 is configured to have an in-container positioning part 87A for positioning within the container. The lid fixing part 87C is for fixing the lid 89 to the housing 87.

[0061] (Washing operation in the washing unit) Next, the operation of the cleaning unit 3 will be described with reference to Figures 8 to 10. Figure 8 is a cross-sectional view of the cleaning unit 3 with the print head 2 set in it. Figure 9 is a diagram showing the state in which the cleaning unit 3 detects that the amount of liquid in the collection container 4 (the amount of cleaning liquid 69B contained after cleaning) is almost full. Figure 10 is a diagram showing the cleaning unit with the collection container 4 removed.

[0062] 8, when cleaning the print head 2, the print head 2 is set (inserted) into the cleaning unit 3. When setting the print head 2, the protective cover 17 of the print head 2 is removed. If the protective cover is provided with a sliding door, which can be slid open during insertion to expose the internal parts of the print head 2 (nozzle, charging electrode, deflection electrode, etc.) inside the cleaning tank 71, the trouble of removing the protective cover 17 can be eliminated.

[0063] Cleaning begins after the print head is set. The cleaning nozzle 72 sprays cleaning liquid towards the print head as shown by →J and K to clean the print head. The cleaning liquid drips downward by gravity as shown by arrow L while cleaning components assembled inside the print head 2, such as the nozzle 21, charging electrode 23, deflection electrode 24, and gutter 25. The cleaning liquid that drips to the bottom of the cleaning tank 71 flows towards the collection container 4 as shown by arrow M, and is collected inside the collection container 4. Once cleaning of the print head is completed, the print head is dried by air nozzle 73.

[0064] When cleaning is performed, cleaning liquid 69B after cleaning falls from cleaning tank 71 and the level of cleaning liquid 69B in collection container 4 rises, but in the case of Fig. 8, the liquid level is still at a low position, float 74 of liquid level detection device 4A does not move, and sensor 76 outputs a liquid level detection signal. This liquid level detection signal is taken into control unit 7 via electric wire 76A. During the period when sensor 76 is outputting the liquid level detection signal, control unit 7 determines that collection container 4 can still sufficiently contain cleaning liquid 69B, and does not display a warning to discharge cleaning liquid 69B.

[0065] When the recovery container 4 is almost full of the cleaning liquid 69B, the state is as shown in FIG. 9. That is, the float 74 rises due to the rise in the liquid level in the recovery container 4, and the sensor 76 cannot output a liquid level detection signal. In this case, the control unit 7 can detect (determine) that the amount of cleaning liquid 69B that can be further accommodated in the recovery container 4 is small and that the recovery container 4 is almost full, so in this state, the control unit displays a warning on the operation display unit 8. For example, a warning may be displayed to indicate that the recovery container 4 should be removed and the cleaning liquid 69B therein should be drained. Note that, although the warning has been described as being displayed only on the operation display unit 8, the warning may be notified to the operator by a buzzer or voice. In addition to the display, a warning may be given by a buzzer or voice. Such a warning allows the operator to remove the recovery container 4 and drain the cleaning liquid 69B in the recovery container 4, as shown in FIG. 10. Then, the empty recovery container 4 is attached to the bottom of the cleaning tank 71 again. Since the sensor of the liquid level detection device is installed on the outside of the recovery container, the recovery container 4 can be easily removed and attached.

[0066] When the recovery container 4 is attached, the float 74 is at the position of the stopper 75A, and therefore the sensor 76 starts outputting a liquid level detection signal. The control unit 7 receives the liquid level detection signal from the sensor 76 and is able to determine that the recovery container 4 has been attached. Based on this determination, the control unit 7 erases the warning display that has been displayed on the operation display unit 8. Alternatively, the control unit 7 can display that the cleaning unit 3 is in an operable (cleanable) state, or can control the operation to cancel the prohibited state of the cleaning operation and allow cleaning.

[0067] (Effects of the embodiment of the present invention) As described above, according to the embodiment of the present invention, the liquid level detection device used in the inkjet recording device is configured to have a float inside the container that moves up and down due to fluctuations in the liquid level, and at least one sensor outside the container that detects when the float approaches a predetermined position, so that the container can be easily attached and detached. Also, in the case of the liquid level detection device described in this embodiment, it is possible to detect whether the container is attached or detached based on the output state of the liquid level detection signal of the liquid level detection device. Furthermore, since the liquid level detection device for detecting the liquid level in the collection container of the cleaning unit can be configured with at least one sensor, it is possible to realize a liquid level detection device with a simple structure and low cost.

[0068] Other Examples Although the embodiment of the present invention has been described above, the present invention is not limited to the above embodiment, and includes various modified examples. Also, the above embodiment has been described in detail to explain the present invention in an easily understandable manner, and the present invention is not necessarily limited to having all of the configurations described. [Explanation of symbols]

[0069] 1...main body, 2...print head, 3...cleaning unit, 4...collection container, 4A...liquid level detection device, 5...conduit, 6...conduit, 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, 21...nozzle, 23...charging electrode, 24...deflection electrode, 25...gutter, 26...switching valve, 31...ink container, 31A...liquid level detection device, 32...auxiliary ink container, 32A...liquid level detection device, 33...solvent container, 33A...liquid level detection device, 34...pump, 35...pump, 37...pump, 38 ...pump, 39...filter, 40...filter, 41...filter, 43...filter, 45...viscosity measuring device, 46...pressure adjusting valve, 47...pressure sensor, 49...solenoid valve, 50...solenoid valve, 53...solenoid valve, 54...solenoid valve, 55...solenoid valve, 56...solenoid valve, 68A...ink, 68B...ink particles, 68C...ink, 69A...solvent, 69B...cleaning liquid, 70...power supply, 71...cleaning tank, 71A...liquid outlet, 71B...mounting, 72...cleaning nozzle, 72A...liquid discharge hole, 72B...liquid discharge hole, 73...air nozzle, 73A...air discharge hole, 73B...air discharge hole, 74...float, 75...holder, 75 A..., stopper, 75B... stopper, 75C to 75F... opening, 76... sensor, 76A... electric wire, 77A... mounting portion, 81... lid block, 81A... print head insertion portion, 82... lid hinge, 83... lid member, 84... liquid joint, 85... cover, 86... magnet, 87... housing, 87A... container internal positioning portion, 87B... magnet fixing portion, 87C... lid fixing portion, 88... seal member, 89... lid, 89A... fixing portion, 91... fixing jig (for main body), 92... fixing jig (for conveyor), 93... mating portion, 100... inkjet recording device, 311... float, 312... holder, 313... sensor , 314...sensor, 315...support member, 321...float, 322...holder, 323...sensor, 324...sensor, 325...support member, 331...float, 332...holder, 333...sensor, 334...sensor, 335...support member, 510...container unit, 520...flow path board, 530...pump unit, 540...solenoid valve unit, 701...microprocessing unit (MPU), 702...read only memory (ROM), 703...random access memory (RAM), 704...print head control circuit, 705...pump control circuit, solenoid valve control circuit,707: Liquid level detection signal input unit; 708: Bus; 801 to 803: Paths; 804: Paths; 805: Paths; 809: Paths; 810: Paths; 811: Paths; 812: Paths; 821: Paths; 825: Paths; 901: Merging path; 903: Branching path;

Claims

1. An inkjet recording device having a main body and a print head, the main body portion has an ink container that contains ink for printing on a print target and supplies ink to the print head portion; the print head unit has a nozzle connected to the ink container and ejecting pressurized ink, a charging electrode for charging ink droplets ejected from the nozzle, a deflection electrode for deflecting the ink droplets charged by the charging electrode, and a gutter for collecting ink not used for printing; The printer further includes a cleaning unit configured separately from the main body and capable of mounting the print head unit, the cleaning unit has a connection portion for mounting a recovery container for containing liquid used to clean the print head unit, and a liquid amount detection portion for detecting when the liquid in the recovery container reaches or exceeds a predetermined amount; The cleaning unit is configured to detect that the collection container is attached, The inkjet recording apparatus, wherein the cleaning unit is configured to prohibit a cleaning operation when it cannot detect that the collection container is attached to the cleaning unit.

2. 2. The inkjet recording apparatus according to claim 1, The ink jet recording apparatus, wherein the cleaning unit is configured to prohibit a cleaning operation when the amount of liquid in the collection container detected by the liquid amount detection portion is equal to or greater than a predetermined amount.

3. 2. The inkjet recording apparatus according to claim 1, When the collection container is not attached to the cleaning unit, a warning to the effect that the cleaning unit is not attached is displayed on a display unit of the main body.

4. 2. The inkjet recording apparatus according to claim 1, An inkjet recording apparatus, characterized in that, when the amount of liquid in the recovery container is equal to or greater than a predetermined amount, a warning is displayed on a display unit of the main body unit to prompt the user to discard the liquid in the recovery container.

5. A recording device having a main body, a print head, and a cleaning unit to which the print head is attached, the main body portion has an ink container that contains ink for printing on a print target and supplies ink to the print head portion; the print head unit has a nozzle connected to the ink container and ejecting pressurized ink, a charging electrode for charging ink droplets ejected from the nozzle, a deflection electrode for deflecting the ink droplets charged by the charging electrode, and a gutter for collecting ink not used for printing; the cleaning unit has a connection portion for attaching a recovery container for containing liquid used to clean the print head portion, and a liquid amount detection portion for detecting when the liquid in the recovery container reaches or exceeds a predetermined amount; The cleaning unit is configured to detect that the collection container is attached, The recording apparatus is configured such that the cleaning unit prohibits a cleaning operation when it cannot detect that the collection container is attached to the cleaning unit.

6. 6. The inkjet recording apparatus according to claim 5, The recording apparatus according to claim 1, wherein the cleaning unit is configured to prohibit a cleaning operation when the amount of liquid in the collection container detected by the liquid amount detection portion is equal to or greater than a predetermined amount.

7. 6. The inkjet recording apparatus according to claim 5, When the collection container is not attached to the cleaning unit, a warning to the effect that the cleaning unit is not attached is displayed on a display unit of the main body.

8. 6. The inkjet recording apparatus according to claim 5, a display unit for displaying a warning to a user to discard the liquid in the recovery container when the amount of the liquid in the recovery container is equal to or greater than a predetermined amount;

Images