Liquid supply device

Abstract

A liquid supply device includes: a liquid storage portion; a plurality of branch paths branched from a path connected to the liquid storage portion and connected to a plurality of tanks disposed at different height positions each lower than the liquid storage portion; a plurality of supply valves disposed in each of the plurality of branch paths; and a control portion that controls the plurality of supply valves to supply liquid from the liquid storage portion to each of the plurality of tanks. The control portion controls the plurality of supply valves so that the supply of the liquid is performed separately in time between tanks in which a height difference is equal to or greater than a predetermined value.

Description

Technical Field

[0001] This invention relates to a liquid supply device. Background Technology

[0002] An ink-circulating inkjet printing device is known that applies positive pressure and negative pressure to a pressurized tank and a negative pressure tank connected to the inkjet head, respectively, to circulate ink and eject ink from the inkjet head for printing.

[0003] Japanese Patent Application Publication No. 2018-1687 discloses an inkjet printing apparatus in which an inkjet head is configured to eject ink in a horizontal direction, enabling printing on surfaces orthogonal to the horizontal direction, such as the side of a cardboard box.

[0004] As such an inkjet printing device, there exists an inkjet printing device that has multiple inkjet heads arranged in the vertical direction, and sprays ink from the inkjet heads onto a surface of the printing medium that is orthogonal to the horizontal direction to perform printing.

[0005] In addition, as an ink-circulating inkjet printing device with multiple inkjet heads arranged vertically as described above, there are inkjet printing devices with multiple ink towers, each having a pressurized tank and a negative pressure tank.

[0006] In this inkjet printing apparatus, multiple ink turrets are connected to a predetermined number of inkjet heads. The multiple ink turrets are positioned at different heights according to the height of the inkjet heads to which they are connected. This minimizes the pressure difference between the inkjet heads caused by the pressure difference between the inkjet head and the pressurized and depressurized tanks, thus converging the nozzle pressure of each inkjet head within a range suitable for stable printing.

[0007] In such an inkjet printing apparatus, there exists an ink supply unit that replenishes ink from a single ink cartridge shared by multiple ink towers to the multiple ink towers using water head pressure. This ink supply unit has multiple branch paths branching from the path connected to the ink cartridge, each branch path connecting to a negative pressure tank of each ink tower. A valve is installed on each branch path, and opening the valve allows ink to flow into the negative pressure tank. Summary of the Invention

[0008] In the inkjet printing apparatus described above, when it is desired to open the valves of multiple branch paths simultaneously to supply ink to multiple negative pressure tanks at the same time, poor ink replenishment may sometimes occur.

[0009] For example, because the head pressure between the negative pressure tank and the ink cartridge in each ink tower is different, the ink supply to each negative pressure tank may sometimes deviate. As a result, the negative pressure tank that is replenished with ink later than the others may sometimes hinder the operation of the device.

[0010] In addition, sometimes, movement of ink from a negative pressure tank that is in a high position and has a small water head pressure with the ink cartridge to a negative pressure tank that is in a low position and has a large water head pressure with the ink cartridge occurs. Thus, a negative pressure tank in which ink is reduced is sometimes generated, which hinders the operation of the device.

[0011] An object of the present application is to provide a liquid supply device capable of reducing poor supply of a liquid such as ink.

[0012] A liquid supply device according to the present application includes a liquid storage portion, a plurality of branch paths branched from a path connected to the liquid storage portion and connected to a plurality of tanks disposed at different height positions lower than the liquid storage portion, a plurality of supply valves disposed in each of the plurality of branch paths, and a control portion that controls the plurality of supply valves to supply liquid from the liquid storage portion to each of the plurality of tanks. The control portion controls the plurality of supply valves so that the supply of the liquid is performed separately in time between tanks having a height difference of a predetermined value or more among the plurality of tanks.

[0013] According to the above-described configuration, it is possible to reduce poor supply of a liquid. BRIEF DESCRIPTION OF DRAWINGS

[0014] Figure 1 is a block diagram showing the configuration of an inkjet printing device according to the embodiment.

[0015] Figure 2 is Figure 1 is a schematic configuration diagram of a conveyance portion and a head unit of the inkjet printing device of

[0016] Figure 3 is Figure 1 is a schematic configuration diagram of a head unit and an ink tower of the inkjet printing device of

[0017] Figure 4 is Figure 1 is a schematic configuration diagram of the ink tower of the inkjet printing device of

[0018] Figure 5 is Figure 1 is a schematic configuration diagram of an ink replenishment portion of the inkjet printing device of

[0019] Figure 6 is a flowchart for explaining an ink replenishment operation in a printing operation.

[0020] Figure 7 is a flowchart for explaining an ink replenishment operation in a printing operation.

[0021] Figure 8 is a flowchart for explaining an operation of the ink replenishment portion at the time of initial filling of ink.

[0022] Figure 9 is a flowchart for explaining the operation of the ink supply section at the time of initial filling of ink.

[0023] Figure 10 is a flowchart for explaining the operation of the ink supply section at the time of initial filling of ink.

[0024] Figure 11 is a flowchart for explaining the operation of the ink supply section at the time of initial filling of ink.

[0025] Figure 12 is a flowchart for explaining the operation of the ink supply section at the time of initial filling of ink. DETAILED DESCRIPTION

[0026] In the following detailed description, for the purposes of explanation, numerous specific details are set forth in order to provide a thorough understanding of the disclosed embodiments. It will be apparent, however, that one or more embodiments can be practiced without some of these specific details. In other instances, well-known structures and devices are shown in block diagram form in order to simplify the figures.

[0027] Hereinafter, embodiments of the present application will be described with reference to the accompanying drawings. Note that the same or similar components and components are designated by the same or similar reference numerals throughout all the drawings for describing the embodiments, and repetitive description is omitted or simplified. Further, it should be noted that the drawings are schematic and different from the actual ones.

[0028] Figure 1 is a block diagram showing the structure of an inkjet printing apparatus 1 provided with a liquid supply device according to an embodiment of the present application. Figure 2 is Figure 1 is a schematic structural view of the conveyance section 2 and the head units 3A, 3B of the inkjet printing apparatus 1 shown in Figure 3 is Figure 1 is a schematic structural view of the head units 3A, 3B and the ink towers 4A to 4C of the inkjet printing apparatus 1 shown in Figure 4 is Figure 1 is a schematic structural view of the ink towers 4A to 4C of the inkjet printing apparatus 1 shown in Figure 5 is Figure 1 is a schematic structural view of the ink supply sections 5A to 5D of the inkjet printing apparatus 1 shown in In the following description, the up, down, left, right, front, and back directions indicated by the arrows of Figure 2 are set as the up, down, left, right, front, and back directions. The up direction is the vertical direction, and the left and right directions and the front and back directions are directions orthogonal to each other and orthogonal to the up direction, and parallel to the horizontal direction. In Figures 2 to 5 , the right direction, the left direction, the up direction, the down direction, the front direction, and the back direction are respectively indicated by RT, LT, UP, DN, FT, and RR.

[0029] As Figure 1 shown, an inkjet printing apparatus 1 is provided with a conveyance section 2, head units 3A, 3B, ink towers 4A to 4C, ink supply sections 5A to 5D, and a control section 6. Further, the liquid supply apparatus is provided with the ink supply sections 5 and the control section 6. In the following description, sometimes the added letters in the marks of the head units 3A, 3B, and the like are omitted to be generically described.

[0030] The conveyance section 2 conveys a printing medium 7. The printing medium 7 has a printed surface 7a on which printing is performed by the head units 3. The printed surface 7a is a surface (vertical surface) orthogonal to the horizontal direction in a state where the printing medium 7 is placed on the conveyance section 2 and is conveyed. The printing medium 7 is, for example, a carton.

[0031] The head units 3A, 3B eject ink in the horizontal direction toward the printed surface 7a of the printing medium 7 to perform printing. The head units 3A, 3B respectively eject ink of two colors. For example, the head unit 3A ejects black and cyan ink, and the head unit 3B ejects magenta and yellow ink. The head units 3A, 3B have the same structure except for the colors of the ejected ink.

[0032] As Figures 1 to 3 shown, the head unit 3 is provided with a plurality of inkjet heads 11. In the present embodiment, the head unit 3 is provided with six inkjet heads 11.

[0033] In the head unit 3, the six inkjet heads 11 are arranged in a staggered manner in the vertical direction. That is, in the head unit 3, the six inkjet heads 11 arranged in the vertical direction are arranged in a manner that positions in the front-rear direction are alternately shifted.

[0034] The inkjet head 11 ejects ink of two colors. The inkjet head 11 has two nozzle rows of a plurality of nozzles (not shown) that respectively linearly arranged in the vertical direction at a predetermined pitch. The two nozzle rows eject ink of different colors from each other.

[0035] The ink towers 4A to 4C supply ink to the head units 3A, 3B. The ink tower 4A supplies ink to the first and second inkjet heads 11 from the bottom in each of the head units 3A, 3B. The ink tower 4B supplies ink to the third and fourth inkjet heads 11 from the bottom in each of the head units 3A, 3B. The ink tower 4C supplies ink to the fifth and sixth inkjet heads 11 from the bottom in each of the head units 3A, 3B.

[0036] Further, in Figure 3 , only one of the head units 3A, 3B is shown, and the illustration of the other head unit 3 is omitted.

[0037] The ink stacks 4A to 4C are arranged so that the height difference between each ink stack and the ink supplying head 11 is equal among all the ink stacks 4A to 4C. Thus, the ink stacks 4A to 4C are arranged at different height positions. The ink stack 4A among the ink stacks 4A to 4C is arranged at the lowest position, and the ink stack 4C is arranged at the highest position.

[0038] The ink stack 4 has ink circulation sections 21A to 21D, a pressure generating section 22, four pressurized air paths 23 (see Figure 4 ) and four negative pressure air paths 24 (see Figure 4 ).

[0039] The ink circulation sections 21A to 21D circulate ink and supply ink to the head 11. The ink circulation sections 21A to 21D supply ink of different colors to the head 11 for ejecting ink of the color held by the ink circulation section 21.

[0040] The ink circulation sections 21A, 21B are connected to two heads 11 arranged at different height positions in the head unit 3A and supply ink to the two heads 11. The ink circulation sections 21C, 21D are connected to two heads 11 arranged at different height positions in the head unit 3B and supply ink to the two heads 11.

[0041] Specifically, the ink circulation sections 21A, 21B of the ink stack 4A supply ink to the first and second heads 11 from the bottom in the head unit 3A. The ink circulation sections 21C, 21D of the ink stack 4A supply ink to the first and second heads 11 from the bottom in the head unit 3B.

[0042] In addition, the ink circulation sections 21A, 21B of the ink stack 4B supply ink to the third and fourth heads 11 from the bottom in the head unit 3A. The ink circulation sections 21C, 21D of the ink stack 4B supply ink to the third and fourth heads 11 from the bottom in the head unit 3B.

[0043] In addition, the ink circulation sections 21A, 21B of the ink stack 4C supply ink to the fifth and sixth heads 11 from the bottom in the head unit 3A. The ink circulation sections 21C, 21D of the ink stack 4C supply ink to the fifth and sixth heads 11 from the bottom in the head unit 3B.

[0044] As shown in Figure 4 , the ink circulation section 21 has a pressurized tank 31, a pressurized tank liquid level sensor 32, a negative pressure tank (tank) 33, a negative pressure tank liquid level sensor 34, a pressurized side ink path 35, a negative pressure side ink path 36, a pump liquid path 37, and an ink pump 38. Furthermore, two (two colors) ink circulation sections 21 that supply ink to the same head unit 3 among the ink circulation sections 21A to 21D of the ink stack 4 are shown in Figure 4 .

[0045] The pressurizing tank 31 stores ink supplied to the inkjet head 11. The pressurizing tank 31 is subjected to application of positive pressure for delivery of ink to the inkjet head 11 by the pressure generating section 22. The pressurizing tank 31 is disposed at a position lower than the inkjet head 11 disposed at a lower position among the two inkjet heads 11 connected to the ink circulation section 21 including the pressurizing tank 31. The pressurizing tanks 31 of the ink circulation sections 21A to 21D of one ink tower 4 are all disposed at the same height position.

[0046] The pressurizing tank liquid level sensor 32 is used to detect whether the liquid level of ink in the pressurizing tank 31 reaches a reference level. The pressurizing tank liquid level sensor 32 outputs a signal indicating "on" in the case where the liquid level in the pressurizing tank 31 is at or above the reference level, and outputs a signal indicating "off" in the case where the liquid level is below the reference level.

[0047] The negative pressure tank 33 receives and stores ink not consumed by the inkjet head 11. In addition, the negative pressure tank 33 stores ink supplied from the ink supply section 5. The negative pressure tank 33 is subjected to application of negative pressure for recovery of ink from the inkjet head 11 by the pressure generating section 22. The negative pressure tank 33 is constituted by a tank having the same shape as the pressurizing tank 31, and is disposed at the same height position as the pressurizing tank 31.

[0048] The negative pressure tank liquid level sensor 34 is used to detect whether the liquid level of ink in the negative pressure tank 33 reaches a reference level. The reference level in the negative pressure tank 33 is the same as the reference level in the pressurizing tank 31. The negative pressure tank liquid level sensor 34 outputs a signal indicating "on" in the case where the liquid level in the negative pressure tank 33 is at or above the reference level, and outputs a signal indicating "off" in the case where the liquid level is below the reference level.

[0049] The pressurizing-side ink path 35 connects the pressurizing tank 31 with the two inkjet heads 11. In the pressurizing-side ink path 35, ink supplied from the pressurizing tank 31 to the two inkjet heads 11 flows.

[0050] The negative pressure-side ink path 36 connects the two inkjet heads 11 with the negative pressure tank 33. In the negative pressure-side ink path 36, ink not consumed by the two inkjet heads 11 and recovered to the negative pressure tank 33 flows.

[0051] The pumping liquid path 37 is a path through which ink pumped by the ink pump 38 flows from the negative pressure tank 33 to the pressurizing tank 31. The upstream end of the pumping liquid path 37 in the direction of circulation of ink is connected to the negative pressure tank 33, and the downstream end is connected to the pressurizing tank 31.

[0052] The ink pump 38 pumps ink from the negative pressure tank 33 to the pressurizing tank 31. The ink pump 38 is disposed midway through the pumping liquid path 37.

[0053] The pressure generating section 22 generates pressure for ink circulation in the pressurizing tank 31 and the negative pressure tank 33 of the ink circulation section 21. Specifically, the pressure generating section 22 draws air from the negative pressure tank 33 via the negative pressure air path 24 and sends out air to the pressurizing tank 31 via the pressurizing air path 23, thereby applying positive pressure to the pressurizing tank 31 and negative pressure to the negative pressure tank 33. The pressure generating section 22 is common to the ink circulation sections 21A to 21D.

[0054] The pressurizing air path 23 connects the pressure generating section 22 and the air layer on the liquid surface of the ink of the pressurizing tank 31. One pressurizing air path 23 is provided corresponding to each of the ink circulation sections 21A to 21D.

[0055] The negative pressure air path 24 connects the pressure generating section 22 and the air layer on the liquid surface of the ink of the negative pressure tank 33. One negative pressure air path 24 is provided corresponding to each of the ink circulation sections 21A to 21D.

[0056] The ink supply sections 5A to 5D supply ink to the negative pressure tanks 33 of the ink circulation sections 21A to 21D, respectively. The ink supply sections 5 supply ink to the negative pressure tanks 33 using the head pressure between the ink cartridge 41 described later and the negative pressure tank 33. In the inkjet printing device 1, the ink supply sections 5 common to the ink towers 4A to 4C are provided for each of the ink colors.

[0057] That is, the ink supply section 5A supplies ink to the ink circulation sections 21A of the ink towers 4A to 4C. The ink supply section 5B supplies ink to the ink circulation sections 21B of the ink towers 4A to 4C. The ink supply section 5C supplies ink to the ink circulation sections 21C of the ink towers 4A to 4C. The ink supply section 5D supplies ink to the ink circulation sections 21D of the ink towers 4A to 4C.

[0058] The ink supply section 5 has the ink cartridge (liquid container) 41, the ink supply path 42, and the ink supply valves (supply valves) 43A to 43C.

[0059] The ink cartridge 41 contains ink used in printing by the inkjet head 11. The ink cartridge 41 is disposed at a position higher than the negative pressure tank 33 of the ink tower 4C. The ink in the ink cartridge 41 is supplied to the negative pressure tanks 33 of the ink circulation sections 21 via the ink supply path 42.

[0060] The ink supply path 42 connects the ink cartridge 41 and the three negative pressure tanks 33 that are the supply destinations of the ink of the ink cartridge 41. In the ink supply path 42, ink flows from the ink cartridge 41 toward the negative pressure tanks 33. The ink supply path 42 has a main path 46 and branch paths 47A to 47C.

[0061] The main path 46 is a path through which ink flows from the ink cartridge 41 to the branch paths 47A to 47C. The upstream end of the main path 46 is connected to the ink cartridge 41, and the downstream end of the main path 46 is connected to the upstream end of the branch path 47B and the upstream end of the branch path 47C.

[0062] The branch paths 47A to 47C are paths that branch from the main path 46 and are connected to the negative pressure tanks 33 of the ink towers 4A to 4C, respectively. The upstream end of the branch path 47A is connected to the middle of the main path 46, and the downstream end of the branch path 47A is connected to the negative pressure tank 33 of the ink tower 4A. The upstream end of the branch path 47B is connected to the downstream end of the main path 46, and the downstream end of the branch path 47B is connected to the negative pressure tank 33 of the ink tower 4B. The upstream end of the branch path 47C is connected to the downstream end of the main path 46, and the downstream end of the branch path 47C is connected to the negative pressure tank 33 of the ink tower 4C.

[0063] Here, the three negative pressure tanks 33 to which the branch paths 47A to 47C are connected are respectively arranged at different heights lower than the ink cartridge 41 in accordance with the height positions of the ink towers 4A to 4C to which the negative pressure tanks 33 are provided. Of the three negative pressure tanks 33 to which the branch paths 47A to 47C are connected, the negative pressure tank 33 to which the branch path 47A is connected is arranged at the lowest position, and the negative pressure tank 33 to which the branch path 47C is connected is arranged at the highest position.

[0064] The ink supply valves 43A to 43C are respectively arranged in the branch paths 47A to 47C and open and close the flow paths of the ink in the branch paths 47A to 47C. The ink supply valves 43 are opened when the ink is supplied to the negative pressure tanks 33.

[0065] The control section 6 controls the operations of the respective sections of the inkjet printing apparatus 1. The control section 6 is configured to include a CPU, a RAM, a ROM, a hard disk, and the like.

[0066] The control section 6 circulates the ink in the ink circulation sections 21A to 21D of the ink towers 4A to 4C and causes the inkjet heads 11 of the head units 3A and 3B to eject the ink to perform printing. In the printing operation, the control section 6 controls the ink supply valves 43A to 43C of the ink supply sections 5A to 5D to supply the ink from the ink cartridge 41 to the respective negative pressure tanks 33. In the ink supply operation in this printing operation, the control section 6 controls the ink supply valves 43A to 43C for each of the ink supply sections 5 to cause the ink supply section 5 to supply the ink to the three negative pressure tanks 33 separately in time. That is, the control section 6 controls the ink supply valves 43 corresponding to the respective negative pressure tanks 33 of the three negative pressure tanks 33 for each of the ink supply sections 5 to perform the processing of supplying the ink to the negative pressure tanks 33 separately in time. The control section 6 also controls the ink supply valves 43A to 43C for each of the ink supply sections 5 in the same manner as above at the time of initial filling of the ink to supply the ink to the three negative pressure tanks 33 separately in time.

[0067] Next, the operation of the inkjet printing apparatus 1 will be described.

[0068] When a print job is input, the control section 6 starts the ink circulation by the ink circulation sections 21A to 21D of the ink towers 4A to 4C. Specifically, the control section 6 causes the pressure generation sections 22 of the ink towers 4A to 4C to cause the pressurizing tanks 31 and the negative pressure tanks 33 to generate respective set pressures for the ink circulation. Thereby, the ink circulation in the ink circulation sections 21A to 21D is started, and the ink flows from the pressurizing tanks 31 to the negative pressure tanks 33 via the inkjet heads 11.

[0069] When the ink circulation is started, the control section 6 causes the print job to be started to be executed. Specifically, the control section 6 performs control to cause the print medium 7 to be conveyed by the conveyance section 2, and the ink to be ejected from the respective inkjet heads 11 of the head units 3A, 3B to print an image on the print medium 7.

[0070] During the execution of the print job, the ink is supplied from the pressurizing tanks 31 to the inkjet heads 11, and the ink not consumed by the inkjet heads 11 is recovered to the negative pressure tanks 33. When the state where the pressurizing tank liquid level sensor 32 is off and the negative pressure tank liquid level sensor 34 is on is reached, the control section 6 causes the ink pump 38 to be driven. Thereby, the ink is transported from the negative pressure tank 33 to the pressurizing tank 31. When the pressurizing tank liquid level sensor 32 becomes on, the control section 6 causes the ink pump 38 to be stopped. The ink circulation is thus performed, and the printing is performed.

[0071] In addition, in this printing operation, the control section 6 performs an ink replenishment operation using the ink replenishment sections 5A to 5D. In this ink replenishment operation, the control section 6 controls the ink replenishment valves 43A to 43C for each of the ink replenishment sections 5 to cause the ink replenishment section 5 to supply ink to the three negative pressure tanks 33 as the supply destinations of the ink in time separation. Details of this ink replenishment operation will be described later.

[0072] When the printing based on the print job is ended, the control section 6 controls the pressure generation sections 22 to end the ink circulation in the ink circulation sections 21A to 21D.

[0073] Next, the above-described ink replenishment operation will be described.

[0074] Figure 6 Figure 7 is a flowchart for explaining the ink replenishment operation. Figure 6 Figure 7 The flowchart of Fig. 10 shows the operation performed by each of the ink replenishment sections 5A to 5D. Therefore, the operation of one ink replenishment section 5 will be described here, and the negative pressure tank 33, the negative pressure tank liquid level sensor 34, and the like in the description represent the components in the ink circulation section 21 as the supply destination of the ink of the ink replenishment section 5. Figure 6 Figure 7 The process of the flowchart of Fig. 10 is started by starting the ink circulation.​​​

[0075] In Figure 6 In step S1, the control section 6 determines whether or not both the pressurizing tank liquid level sensor 32 and the negative pressure tank liquid level sensor 34 of the ink tower 4A are disconnected.

[0076] In the case where it is determined that both the pressurizing tank liquid level sensor 32 and the negative pressure tank liquid level sensor 34 of the ink tower 4A are disconnected (step S1: "Yes"), in step S2, the control section 6 opens the ink supply valve 43A. Thereby, ink is supplied to the negative pressure tank 33 of the ink tower 4A via the branch path 47A by the head pressure between the ink cartridge 41 and the negative pressure tank 33 of the ink tower 4A, and the negative pressure of the negative pressure tank 33.

[0077] Next, in step S3, the control section 6 determines whether or not the negative pressure tank liquid level sensor 34 of the ink tower 4A is on. In the case where it is determined that the negative pressure tank liquid level sensor 34 is not on (step S3: "No"), the control section 6 repeats step S3.

[0078] In the case where it is determined that the negative pressure tank liquid level sensor 34 is on (step S3: "Yes"), in step S4, the control section 6 closes the ink supply valve 43A. Thereby, the supply of ink to the negative pressure tank 33 of the ink tower 4A is stopped. After that, the control section 6 proceeds to step S5.

[0079] In step S1, in the case where it is determined that at least either one of the pressurizing tank liquid level sensor 32 and the negative pressure tank liquid level sensor 34 of the ink tower 4A is on (step S1: "No"), the control section 6 proceeds to step S5.

[0080] In step S5, the control section 6 determines whether or not both the pressurizing tank liquid level sensor 32 and the negative pressure tank liquid level sensor 34 of the ink tower 4B are disconnected.

[0081] In the case where it is determined that both the pressurizing tank liquid level sensor 32 and the negative pressure tank liquid level sensor 34 of the ink tower 4B are disconnected (step S5: "Yes"), in step S6, the control section 6 opens the ink supply valve 43B. Thereby, ink is supplied to the negative pressure tank 33 of the ink tower 4B via the branch path 47B by the head pressure between the ink cartridge 41 and the negative pressure tank 33 of the ink tower 4B, and the negative pressure of the negative pressure tank 33.

[0082] Next, in step S7, the control section 6 determines whether or not the negative pressure tank liquid level sensor 34 of the ink tower 4B is on. In the case where it is determined that the negative pressure tank liquid level sensor 34 is not on (step S7: "No"), the control section 6 repeats step S7.

[0083] If the control unit determines that the negative pressure tank liquid level sensor 34 is activated (step S7: "Yes"), in step S8, the control unit 6 closes the ink supply valve 43B. This stops the supply of ink to the negative pressure tank 33 of the ink tower 4B. Afterwards, the control unit 6 proceeds to step S9.

[0084] In step S5, if it is determined that at least one of the pressure tank liquid level sensor 32 and the negative pressure tank liquid level sensor 34 of the ink tower 4B is turned on (step S5: "No"), the control unit 6 proceeds to step S9.

[0085] In step S9, the control unit 6 determines whether the pressure tank liquid level sensor 32 and the negative pressure tank liquid level sensor 34 of the ink tower 4C are both disconnected.

[0086] If both the pressure tank liquid level sensor 32 and the negative pressure tank liquid level sensor 34, which are identified as being in the 4C phase, are disconnected (step S9: "Yes"), then... Figure 7 In step S10, the control unit 6 opens the ink supply valve 43C. As a result, ink is supplied to the negative pressure tank 33 of the ink tower 4C via the branch path 47C using the water head pressure between the ink cartridge 41 and the negative pressure tank 33 of the ink tower 4C, as well as the negative pressure of the negative pressure tank 33.

[0087] Next, in step S11, the control unit 6 determines whether the negative pressure tank liquid level sensor 34 of the ink tower 4C is turned on. If it is determined that the negative pressure tank liquid level sensor 34 is not turned on (step S11: "No"), the control unit 6 repeats step S11.

[0088] If the control unit determines that the negative pressure tank liquid level sensor 34 is activated (step S11: "Yes"), in step S12, the control unit 6 closes the ink supply valve 43C. This stops the supply of ink to the negative pressure tank 33 of the ink tower 4C. Afterwards, the control unit 6 proceeds to step S13.

[0089] exist Figure 6 In step S9, if at least one of the pressure tank liquid level sensor 32 and the negative pressure tank liquid level sensor 34 of the ink tower 4C is turned on (step S9: "No"), the control unit 6 enters... Figure 7 Step S13.

[0090] In step S13, the control unit 6 determines whether the ink cycle has ended. If it is determined that the ink cycle has not ended (step S13: "No"), the control unit 6 returns to step S1.

[0091] When the control unit 6 determines that the ink cycle has ended (step S13: "Yes"), a series of actions are completed.

[0092] Next, the operation of the ink supply unit 5 during the initial filling of ink in the inkjet printing apparatus 1 will be explained.

[0093] The initial filling of ink is to fill the ink in each of the ink circulation sections 21 and each of the inkjet heads 11 in a state where no ink is present in the ink circulation sections 21 and the inkjet heads 11. The initial filling of ink is, for example, to set the inkjet printing apparatus 1 in a state where printing operation is possible at the end of a maintenance work performed to remove the ink from the ink circulation sections 21 and the inkjet heads 11, or at the completion of the inkjet printing apparatus 1.

[0094] Figures 8 to 12 is a flowchart for explaining the operation of the ink supply section 5 at the time of the initial filling of ink. Figures 8 to 12 The flowchart of Figure 6 , Figure 7 The flowchart of Figure 6 The operation of one ink supply section 5 is explained as with the explanation of the flowchart of

[0095] When the initial filling of ink is started, in step S21 of Figure 8 , the control section 6 determines whether the negative pressure tank liquid level sensor 34 of the ink tower 4A is on. In the case where the negative pressure tank liquid level sensor 34 of the ink tower 4A is determined to be on (step S21: YES), the control section 6 proceeds to step S42 described later.

[0096] Here, at the start of the initial filling, the negative pressure tanks 33 of the ink towers 4A to 4C are empty, and therefore the negative pressure tank liquid level sensors 34 of the ink towers 4A to 4C are off.

[0097] In the case where the negative pressure tank liquid level sensor 34 of the ink tower 4A is determined to be off (step S21: NO), in step S22, the control section 6 opens the ink supply valve 43A.

[0098] Here, at the time of the initial filling, the pressure generation section 22 applies positive pressure to the pressurizing tank 31 and opens the negative pressure tank 33 to the atmosphere. Therefore, when the ink supply valve 43A is opened, ink is supplied to the negative pressure tank 33 of the ink tower 4A via the branch path 47A only by the head pressure between the ink cartridge 41 and the negative pressure tank 33 of the ink tower 4A.

[0099] Next, in step S23, the control section 6 determines whether a prescribed time has elapsed since the ink supply valve 43A was opened. Here, the prescribed time is set in advance as the opening time of the ink supply valve 43 once at the period before the negative pressure tank liquid level sensor 34 is turned on for the first time in the ink towers 4A to 4C. The prescribed time is set for each ink tower 4 in accordance with the head pressure between the ink cartridge 41 and the negative pressure tank 33 of each ink tower 4 so that the amount of ink supplied when the ink supply valve 43 is opened for the prescribed time becomes a prescribed amount.

[0100] If it is determined that the specified time has not elapsed (step S23: "No"), in step S24, the control unit 6 determines whether the liquid level sensor 34 of the negative pressure tank of ink tower 4A is connected. If it is determined that the liquid level sensor 34 of the negative pressure tank of ink tower 4A is disconnected (step S24: "No"), the control unit 6 returns to step S23.

[0101] If the control unit determines that the liquid level sensor 34 of the negative pressure tank of ink tower 4A is activated (step S24: "Yes"), in step S25, the control unit 6 closes the ink supply valve 43A. This stops the supply of ink to the negative pressure tank 33 of ink tower 4A. Afterwards, the control unit 6 proceeds to step S42, which will be described later.

[0102] In step S23, if it is determined that a predetermined time has elapsed (step S23: "Yes"), in step S26, the control unit 6 closes the ink supply valve 43A. This stops the supply of ink to the negative pressure tank 33 of the ink tower 4A.

[0103] Next, in step S27, the control unit 6 determines whether the liquid level sensor 34 of the negative pressure tank of ink tower 4A is turned on. If it is determined that the liquid level sensor 34 of the negative pressure tank of ink tower 4A is turned on (step S27: "Yes"), the control unit 6 proceeds to step S42, which will be described later.

[0104] If the liquid level sensor 34 of the negative pressure tank of Ink Tower 4A is determined to be disconnected (step S27: "No"), then Figure 9 In step S28, the control unit 6 determines whether the liquid level sensor 34 of the negative pressure tank of ink tower 4B is turned on. If it is determined that the liquid level sensor 34 of the negative pressure tank of ink tower 4B is turned on (step S28: "Yes"), the control unit 6 proceeds to step S44, which will be described later.

[0105] If the liquid level sensor 34 of the negative pressure tank of ink tower 4B is determined to be disconnected (step S28: "No"), in step S29, the control unit 6 opens the ink supply valve 43B. As a result, ink is supplied to the negative pressure tank 33 of ink tower 4B via branch path 47B using only the head pressure between ink cartridge 41 and negative pressure tank 33 of ink tower 4B.

[0106] Next, in step S30, the control unit 6 determines whether a predetermined time has elapsed since the ink supply valve 43B was opened.

[0107] If it is determined that the specified time has not elapsed (step S30: "No"), in step S31, the control unit 6 determines whether the liquid level sensor 34 of the negative pressure tank of ink tower 4B is turned on. If it is determined that the liquid level sensor 34 of the negative pressure tank of ink tower 4B is turned off (step S31: "No"), the control unit 6 returns to step S30.

[0108] If the control unit determines that the liquid level sensor 34 of the negative pressure tank of ink tower 4B is activated (step S31: "Yes"), in step S32, the control unit 6 closes the ink supply valve 43B. This stops the supply of ink to the negative pressure tank 33 of ink tower 4B. Afterwards, the control unit 6 proceeds to step S44, which will be described later.

[0109] In step S30, if it is determined that a predetermined time has elapsed (step S30: "Yes"), in step S33, the control unit 6 closes the ink supply valve 43B. This stops the supply of ink to the negative pressure tank 33 of the ink tower 4B.

[0110] Next, in step S34, the control unit 6 determines whether the liquid level sensor 34 of the negative pressure tank of ink tower 4B is turned on. If it is determined that the liquid level sensor 34 of the negative pressure tank of ink tower 4B is turned on (step S34: "Yes"), the control unit 6 proceeds to step S44, which will be described later.

[0111] If the negative pressure tank liquid level sensor 34 of the ink tower 4B is determined to be disconnected (step S34: "No"), then Figure 10 In step S35, the control unit 6 determines whether the liquid level sensor 34 of the negative pressure tank of the ink tower 4C is turned on. If it is determined that the liquid level sensor 34 of the negative pressure tank of the ink tower 4C is turned on (step S35: "Yes"), the control unit 6 proceeds to step S46, which will be described later.

[0112] If the liquid level sensor 34 of the negative pressure tank of ink tower 4C is determined to be disconnected (step S35: "No"), in step S36, the control unit 6 opens the ink supply valve 43C. As a result, ink is supplied to the negative pressure tank 33 of ink tower 4C via branch path 47C using only the head pressure between ink cartridge 41 and negative pressure tank 33 of ink tower 4C.

[0113] Next, in step S37, the control unit 6 determines whether a predetermined time has elapsed since the ink supply valve 43C was opened.

[0114] If it is determined that the specified time has not elapsed (step S37: "No"), in step S38, the control unit 6 determines whether the liquid level sensor 34 of the negative pressure tank of ink tower 4C is turned on. If it is determined that the liquid level sensor 34 of the negative pressure tank of ink tower 4C is turned off (step S38: "No"), the control unit 6 returns to step S37.

[0115] If the control unit determines that the liquid level sensor 34 of the negative pressure tank of ink tower 4C is activated (step S38: "Yes"), in step S39, the control unit 6 closes the ink supply valve 43C. This stops the supply of ink to the negative pressure tank 33 of ink tower 4C. Afterwards, the control unit 6 proceeds to step S46, which will be described later.

[0116] In step S37, if it is determined that a predetermined time has elapsed (step S37: "Yes"), in step S40, the control unit 6 closes the ink supply valve 43C. This stops the supply of ink to the negative pressure tank 33 of the ink tower 4C.

[0117] Next, in step S41, the control unit 6 determines whether the liquid level sensor 34 of the negative pressure tank of the ink tower 4C is turned on.

[0118] If the liquid level sensor 34 of the negative pressure tank of Ink Tower 4C is determined to be disconnected (step S41: "No"), the control unit 6 returns. Figure 8 Step S21.

[0119] exist Figure 8 In step S42, the control unit 6 determines whether the liquid level sensor 34 of the negative pressure tank of ink tower 4B is connected. If it is determined that the liquid level sensor 34 of the negative pressure tank of ink tower 4B is disconnected (step S42: "No"), the control unit 6 enters... Figure 9 Step S29.

[0120] If the control unit 6 determines that the liquid level sensor 34 of the negative pressure tank of ink tower 4B is on (step S42: "Yes"), in step S43, the control unit 6 determines whether the liquid level sensor 34 of the negative pressure tank of ink tower 4C is on. If the control unit 6 determines that the liquid level sensor 34 of the negative pressure tank of ink tower 4C is off (step S43: "No"), the control unit 6 enters... Figure 10 Step S36.

[0121] If the negative pressure tank liquid level sensor 34 of the ink tower 4C is determined to be activated (step S43: "Yes"), the control unit 6 enters the process described later. Figure 11 Step S48.

[0122] exist Figure 9 In step S44, the control unit 6 determines whether the liquid level sensor 34 of the negative pressure tank of ink tower 4A is connected. If it is determined that the liquid level sensor 34 of the negative pressure tank of ink tower 4A is disconnected (step S44: "No"), the control unit 6 proceeds to... Figure 8 Step S22.

[0123] If the control unit determines that the liquid level sensor 34 of the negative pressure tank of ink tower 4A is on (step S44: "Yes"), in step S45, the control unit 6 determines whether the liquid level sensor 34 of the negative pressure tank of ink tower 4C is on. If the control unit determines that the liquid level sensor 34 of the negative pressure tank of ink tower 4C is off (step S45: "No"), the control unit 6 enters... Figure 10 Step S36.

[0124] If the negative pressure tank liquid level sensor 34 of the ink tower 4C is activated (step S45: "Yes"), the control unit 6 enters the process described later. Figure 11Step S48.

[0125] exist Figure 10 In step S46, the control unit 6 determines whether the liquid level sensor 34 of the negative pressure tank of ink tower 4A is connected. If it is determined that the liquid level sensor 34 of the negative pressure tank of ink tower 4A is disconnected (step S46: "No"), the control unit 6 enters... Figure 8 Step S22.

[0126] If the control unit 6 determines that the liquid level sensor 34 of the negative pressure tank of ink tower 4A is on (step S46: "Yes"), in step S47, the control unit 6 determines whether the liquid level sensor 34 of the negative pressure tank of ink tower 4B is on. If the control unit 6 determines that the liquid level sensor 34 of the negative pressure tank of ink tower 4B is off (step S47: "No"), the control unit 6 enters... Figure 9 Step S29.

[0127] If the liquid level sensor 34 of the negative pressure tank of ink tower 4B is determined to be turned on (step S47: "Yes"), the control unit 6 enters the process described later. Figure 11 Step S48.

[0128] Through the above-mentioned Figures 8 to 10 In steps S21 to S47, ink is supplied to the negative pressure tanks 33 of ink towers 4A to 4C in a time-separated manner, and the liquid level sensor 34 of the negative pressure tanks 4A to 4C is activated first. Afterwards, the process proceeds... Figure 11 Step S48.

[0129] Here, after the negative pressure tank liquid level sensor 34 of ink towers 4A to 4C is first turned on, similar to the ink circulation during the printing operation described above, when the pressure tank liquid level sensor 32 is off and the negative pressure tank liquid level sensor 34 is on, the ink pump 38 is driven; when the pressure tank liquid level sensor 32 is turned on, the ink pump 38 is stopped. Furthermore, as described above, positive pressure is applied to the pressure tank 31, so ink flows from the pressure tank 31 towards the inkjet head 11.

[0130] Figures 11 to 12 The processing in steps S48 to S59 is the same as described above. Figure 6 , Figure 7 The processing of S1 to S12 in the flowchart is the same.

[0131] exist Figure 12 In step S60, the control unit 6 determines whether the initial filling of ink has ended. Here, the control unit 6 determines that the initial filling of ink has ended when the pressure tank liquid level sensor 32 is activated a predetermined number of times.

[0132] If it is determined that the initial ink filling has not been completed (step S60: "No"), the control unit 6 returns. Figure 11the step S48.

[0133] In a case where the control section 6 determines that the initial filling of ink is ended (step S60: YES), the series of actions ends.

[0134] As explained above, in the inkjet printing device 1, the control section 6 controls the ink supply valves 43A to 43C for each of the ink supply sections 5 to cause the ink supply sections 5 to supply ink to the ink supply destinations, i.e., the respective negative pressure tanks 33, in time separation. That is, the control section 6 controls the ink supply valves 43 corresponding to the respective negative pressure tanks 33 of the three negative pressure tanks 33 for each of the ink supply sections 5 to perform the processing for supplying ink to the negative pressure tanks 33 in time stagger.

[0135] Here, unlike the present embodiment, in a case where it is intended to supply ink to a plurality of negative pressure tanks 33 at the same time, since the head pressures between the respective negative pressure tanks 33 and the ink cartridge 41 are different, there is a risk that the supply of ink to the negative pressure tanks 33 becomes poor.

[0136] For example, there is a risk that the amount of supply of ink to the respective negative pressure tanks 33 becomes deviated. Due to this, there is a risk that the negative pressure tank 33 to which ink cannot be supplied is generated, and the action of the inkjet printing device 1 is hindered.

[0137] In addition, there is a risk that ink moves between the negative pressure tanks 33 from the negative pressure tank 33 in the high position and having a small head pressure with the ink cartridge 41 to the negative pressure tank 33 in the low position and having a large head pressure with the ink cartridge 41. Due to this, there is a risk that the negative pressure tank 33 in which ink is reduced is generated, and the action of the inkjet printing device 1 is hindered.

[0138] To this end, in the inkjet printing device 1, by performing the supply of ink to the respective negative pressure tanks 33 by the ink supply sections 5 in time separation, it is possible to reduce the poor supply of ink to the negative pressure tanks 33 as explained above.

[0139] Further, it is also possible to control the ink supply valves 43A to 43C to allow the supply of ink to be performed in time separation between the negative pressure tanks 33 having a height difference of a prescribed value or more, and to supply ink at the same time between the negative pressure tanks 33 having a height difference smaller than the prescribed value. Here, the prescribed value of the height difference between the negative pressure tanks 33 is set to a lower limit value of the height difference based on experiments or the like, which has a risk that the poor supply of ink as explained above is generated.

[0140] For example, assume that the height difference between the ink towers 4A and 4C is equal to or greater than a predetermined value, and the height differences between the ink towers 4A and 4B and between the ink towers 4B and 4C are less than the predetermined value. The height difference of the negative pressure tanks 33 included in the ink towers 4 is equal to the height difference of the ink towers 4. In this case, the ink supply valves 43A to 43C can also be controlled to allow the supply of ink to be performed separately in time between the negative pressure tanks 33 of the ink towers 4A and 4C, and simultaneously between the negative pressure tanks 33 of the ink towers 4A and 4B and between the negative pressure tanks 33 of the ink towers 4B and 4C.

[0141] By so doing, it is also possible to reduce the supply failure of ink to the negative pressure tanks 33 as described above.

[0142] Further, in the above-described embodiment, the structure in which the ink supply destination of one ink supply section 5 is three negative pressure tanks 33 is shown, but the number of negative pressure tanks 33 as the supply destination is not limited to this, and can be plural.

[0143] Further, the present application can be applied to a liquid supply device that supplies a liquid other than ink.

[0144] The embodiment of the present disclosure has, for example, the following structure.

[0145] The liquid supply device includes: a liquid storage section; a plurality of branch paths that branch from a path connected to the liquid storage section and are connected to a plurality of tanks disposed at different height positions that are lower than the liquid storage section; a plurality of supply valves disposed in each of the plurality of branch paths; and a control section that controls the plurality of supply valves to supply liquid from the liquid storage section to each of the plurality of tanks. The control section controls the plurality of supply valves so that the supply of the liquid is performed separately in time between tanks in which the height difference is equal to or greater than a predetermined value among the plurality of tanks.

[0146] The control section can control the plurality of supply valves so that the supply of the liquid is performed separately in time for each of the plurality of tanks.

[0147] The control section can control the plurality of supply valves corresponding to each of the plurality of tanks to perform processing for supplying the liquid to each of the plurality of tanks at different times for each of the plurality of tanks.

[0148] The embodiments of the present application have been described above. However, the present application can be embodied in other ways without departing from the spirit and scope thereof. Therefore, the present embodiments are illustrative in all aspects and are not restrictive, the scope of the present application is indicated by the appended claims, not by the foregoing description, and all changes within the meaning and range equivalent to the claims are included in the scope of the present application.

[0149] Also, the effects described in the embodiments of the present application are only examples of the most outstanding effects achieved by the present application. Accordingly, the effects of the present application are not limited to those described in the embodiments of the present application.

Claims

1. A liquid supply device comprising: a liquid storage portion; a plurality of branch paths branched from a path connected to the liquid storage portion, and connected to a plurality of tanks disposed at different height positions each lower than the liquid storage portion; a plurality of supply valves disposed in each of the plurality of branch paths; and a control portion that controls the plurality of supply valves to supply liquid from the liquid storage portion to each of the plurality of tanks, wherein the control portion controls the plurality of supply valves so that the supply of the liquid is performed separately in time between tanks having a height difference of a prescribed value or more among the plurality of tanks.

2. The liquid supply device according to claim 1, wherein the control portion controls the plurality of supply valves so that the supply of the liquid is performed separately in time for each of the plurality of tanks.

3. The liquid supply device according to claim 1, wherein the control portion controls the plurality of supply valves corresponding to each of the plurality of tanks so that the process of supplying the liquid to each of the plurality of tanks is performed separately in time for each of the plurality of tanks. ​ ​ wherein ​ ​ ​ ​ ​

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