JP2021181186A - Printer - Google Patents

Abstract

To reduce time needed from removing ink.SOLUTION: A printer utilizes a water head difference to discharge ink in an upper print part 4 to an ink cartridge 51 and utilizes the water head difference to discharge the ink in a compression tank 31 and a negative pressure tank 33B of a lower print part 5 to the ink cartridge 51. Then, the printer sends the ink in a buffer tank 43B to a buffer tank 43A and utilizes the water head difference to discharge the ink from the buffer tank 43A to the ink cartridge 51.SELECTED DRAWING: Figure 2

Description

The present invention relates to a printing apparatus.

There is known a printing apparatus each having an inkjet head and having two printing units arranged one above the other (see Patent Document 1).

In such a printing apparatus, when the inkjet head is replaced or the like, ink may be removed by removing the ink stored in the upper and lower printing units.

Japanese Unexamined Patent Publication No. 2010-99955

In ink removal in a printing device provided with upper and lower printing units as described above, the flow rate of ink discharged from the lower printing unit is small because the head difference between the lower printing unit and the ink ejection destination is small. , The time required for ink removal may be long. When performing work that requires ink removal, if it takes a long time to remove ink, the time required for the entire work becomes long. Therefore, there has been a demand for shortening the time required for ink removal.

The present invention has been made in view of the above, and an object of the present invention is to provide a printing apparatus capable of shortening the time required for ink removal.

In order to achieve the above object, the printing apparatus of the present invention is arranged at a position lower than the first printing unit, which stores ink and prints using the stored ink, and the first printing unit, and stores the ink. The second printing unit that prints using the stored ink, the discharged ink storage unit located at a position lower than the second printing unit, and the ink to be discharged in the first printing unit and the second printing unit. The discharge operation unit is provided with an operation unit that performs an operation of discharging the ink to the discharge ink storage unit by using a water head difference, and the discharge operation unit discharges at least a part of the ink to be discharged in the second printing unit. The liquid is sent to the first printing unit, and the liquid is discharged from the first printing unit to the discharged ink storage unit by utilizing the head difference.

According to the printing apparatus of the present invention, the time required for ink removal can be shortened.

It is a schematic block diagram of the printing apparatus which concerns on embodiment. FIG. 3 is a schematic configuration diagram of an upper printing unit, a lower printing unit, an ink supply unit, and a pressure generating unit of the printing apparatus shown in FIG. 1. It is a flowchart for demonstrating the operation of ink removal. It is a flowchart for demonstrating the operation of ink removal. It is explanatory drawing of the flow of ink in the operation of ink removal. It is explanatory drawing of the flow of ink in the operation of ink removal. It is explanatory drawing of the flow of ink in the operation of ink removal. It is explanatory drawing of the flow of ink in the operation of ink removal. It is explanatory drawing of the flow of ink in the operation of ink removal. It is explanatory drawing of the flow of ink in the operation of ink removal.

Hereinafter, embodiments of the present invention will be described with reference to the drawings. The same or equivalent parts and components are designated by the same or equivalent reference numerals throughout the drawings.

The embodiments shown below exemplify an apparatus or the like for embodying the technical idea of the present invention, and the technical idea of the present invention includes the material, shape, structure, arrangement, etc. of each component. Is not specified as the following. The technical idea of the present invention can be modified in various ways within the scope of claims.

FIG. 1 is a schematic configuration diagram of a printing apparatus according to an embodiment of the present invention. FIG. 2 is a schematic configuration diagram of an upper printing unit, a lower printing unit, an ink supply unit, and a pressure generation unit of the printing apparatus shown in FIG. In the following description, the vertical and horizontal directions of the paper surface in FIG. 1 are defined as the vertical and horizontal directions. Further, the vertical direction in the following description is a vertical direction.

As shown in FIG. 1, the printing apparatus 1 according to the present embodiment includes a web roll support shaft 2, a transport unit 3, upper printing units (corresponding to the first printing unit) 4A to 4E, and a lower printing unit. It includes 5A to 5E (corresponding to the second printing unit), ink supply units 6A to 6E, a pressure generation unit 7, a take-up shaft 8, and a control unit 9. It should be noted that the subscripts of the alphabet in the symbols of the upper printing units 4A to 4E and the like may be omitted and collectively described.

The web roll support shaft 2 rotatably supports the web roll 10. The web roll 10 is a roll of the web W.

The transport unit 3 pulls out the web W from the web roll 10 and transports the web W toward the take-up shaft 8. The transport unit 3 includes a pair of transport rollers 11. The pair of transport rollers 11 transport the web W toward the take-up shaft 8 while niping the web W.

The upper printing units 4A to 4E print an image on the surface of the web W. The upper printing units 4A to 4E store inks of different colors, and print on the web W using the stored inks. The upper printing units 4A to 4E are arranged in parallel in the transport direction (left-right direction) of the web W. The details of the upper printing unit 4 will be described later.

The lower printing units 5A to 5E print an image on the back surface of the web W. The lower printing units 5A to 5E store ink of the same color as the upper printing units 4A to 4E, respectively, and print on the web W using the stored ink. The lower printing units 5A to 5E are arranged in parallel with the transport direction (left-right direction) of the web W at a position lower (lower) than the upper printing units 4A to 4E. Details of the lower printing unit 5 will be described later.

The ink supply units 6A to 6E supply ink to the upper printing units 4A to 4E and the lower printing units 5A to 5E, respectively. The details of the ink supply unit 6 will be described later.

The pressure generation unit 7 generates pressure for ink circulation in the pressure tank 31A and the negative pressure tank 33A of the upper printing unit 4, which will be described later, and the pressure tank 31B and the negative pressure tank 33B of the lower printing unit 5. The pressure generation unit 7 is common to the upper printing units 4A to 4E and the lower printing units 5A to 5E. The details of the pressure generating unit 7 will be described later.

The take-up shaft 8 winds up and holds the web W printed by the upper printing unit 4 and the lower printing unit 5.

The control unit 9 controls the operation of the entire printing device 1. The control unit 9 includes a CPU, RAM, ROM, a hard disk, and the like.

Next, the details of the upper printing unit 4, the lower printing unit 5, the ink supply unit 6, and the pressure generating unit 7 described above will be described with reference to FIG. Note that FIG. 2 shows an upper printing unit 4, a lower printing unit 5, and an ink supply unit 6 for one color.

As shown in FIG. 2, the upper printing unit 4 includes an inkjet head 21A and an ink circulation mechanism 22A.

The inkjet head 21A ejects the ink supplied by the ink circulation mechanism 22A. The inkjet head 21A includes a plurality of nozzles for ejecting ink, a chamber for storing ink ejected from the nozzles, and a plurality of piezoelectric elements (none of which are shown) arranged in the chamber to eject ink from the nozzles. Be prepared. The nozzle is open to the nozzle surface which is the lower surface of the inkjet head 21A.

The ink circulation mechanism 22A supplies ink to the inkjet head 21A while circulating the ink. The ink circulation mechanism 22A includes a pressurized tank (corresponding to a tank) 31A, a pressurized tank liquid level sensor 32A, a negative pressure tank (corresponding to a tank) 33A, a negative pressure tank liquid level sensor 34A, and an ink bath 35A. 36A, inflow pipe 37A, outflow pipe 38A, ink circulation pipes 39A to 41A, ink circulation pump 42A, buffer tank 43A, buffer tank liquid level sensor 44A, buffer tank air release valve 45A, and buffer tank. It includes an air release pipe 46A, an air filter 47A, an ink supply valve 48A, and a connection pipe 49A.

The pressure tank 31A stores ink to be supplied to the inkjet head 21A. The ink in the pressure tank 31A is supplied to the inkjet head 21A via the ink circulation pipe 39A, the ink bath 35A, and the inflow pipe 37A. That is, the pressure tank 31A is arranged on the upstream side of the inkjet head 21A in the ink circulation direction. In the pressure tank 31A, an air layer is formed on the liquid surface of the ink.

The pressure tank liquid level sensor 32A detects whether or not the liquid level height of the ink in the pressure tank 31A has reached the reference height. The pressure tank liquid level sensor 32A outputs a signal indicating "on" when the liquid level height in the pressure tank 31A is equal to or higher than the reference height, and "off" when the liquid level height is less than the reference height. The indicated signal is output.

The negative pressure tank 33A stores the ink returned without being consumed by the inkjet head 21A. That is, the negative pressure tank 33A is arranged on the downstream side of the inkjet head 21A in the ink circulation direction. In the negative pressure tank 33A, an air layer is formed on the liquid surface of the ink.

The negative pressure tank liquid level sensor 34A detects whether or not the liquid level height of the ink in the negative pressure tank 33A has reached the reference height. The negative pressure tank liquid level sensor 34A outputs a signal indicating "on" when the liquid level height in the negative pressure tank 33A is equal to or higher than the reference height, and turns "off" when the liquid level in the negative pressure tank 33A is less than the reference height. The indicated signal is output.

The ink bath 35A supplies the ink sent from the pressure tank 31A via the ink circulation pipe 39A to the inkjet head 21A via the inflow pipe 37A.

The ink bath 36A collects the ink not consumed by the inkjet head 21A via the outflow pipe 38A and flows it to the ink circulation pipe 40A.

The inflow pipe 37A forms an ink flow path for allowing the ink supplied by the ink circulation portion 22A to flow into the inkjet head 21A. The inflow pipe 37A connects the inkjet head 21A and the ink bath 35A.

The outflow tube 38A forms a flow path of ink that flows out from the inkjet head 21A and goes to the ink bath 36A without being consumed by the inkjet head 21A. The outflow pipe 38A connects the inkjet head 21A and the ink bath 36A.

The ink circulation pipe 39A connects the pressure tank 31A and the ink bath 35A. The ink circulation tube 40A connects the ink bath 36A and the negative pressure tank 33A. The ink circulation pipe 41A connects the pressure tank 31A and the negative pressure tank 33A.

The ink circulation pump 42A sends ink from the negative pressure tank 33A to the pressure tank 31A via the ink circulation pipe 41A during ink circulation. Further, the ink circulation pump 42A sends ink from the buffer tank 43A to the pressure tank 31A via a part of the connection pipe 49A and the ink circulation pipe 41A when the ink is supplied to the pressure tank 31A.

The buffer tank 43A stores ink to be supplied to the pressure tank 31A. The buffer tank 43A receives ink from the ink cartridge 51, which will be described later, and stores the supplied ink. In the buffer tank 43A, an air layer is formed on the liquid surface of the ink. The buffer tank 43A is connected to the ink circulation pipe 41A via the connecting pipe 49A. The buffer tank 43A is arranged at a position (lower) lower than the nozzle surface of the inkjet head 21A.

The buffer tank liquid level sensor 44A detects whether or not the liquid level height of the ink in the buffer tank 43A has reached the reference height. The buffer tank liquid level sensor 44A outputs a signal indicating "on" when the liquid level height in the buffer tank 43A is equal to or higher than the reference height, and a signal indicating "off" when the liquid level height is less than the reference height. Is output.

The buffer tank open-air valve 45A is used to switch the buffer tank 43A between a closed state (closed from the atmosphere) and an open state (open to the atmosphere), so that the air in the buffer tank open-air pipe 46A can be switched. Open and close the flow path of.

The buffer tank air opening pipe 46A forms an air flow path for opening the buffer tank 43A to the atmosphere. One end of the buffer tank open-air pipe 46A is connected to the air layer of the buffer tank 43A, and the other end (open end to the atmosphere) is connected to the atmosphere through the air filter 47A.

The air filter 47A prevents dust and the like in the air from entering the buffer tank atmospheric opening pipe 46A. The air filter 47A is installed at the open end of the buffer tank open air pipe 46A.

The ink supply valve 48A opens and closes the ink flow path in the connecting tube 49A.

The connection pipe 49A connects the ink circulation pipe 41A and the buffer tank 43A. One end of the connecting pipe 49A is connected to a portion between the negative pressure tank 33A of the ink circulation pipe 41A and the ink circulation pump 42A, and the other end is connected to the buffer tank 43A.

The lower printing unit 5 includes an inkjet head 21B and an ink circulation mechanism 22B.

The inkjet head 21B ejects the ink supplied by the ink circulation mechanism 22B. The inkjet head 21B has the same configuration as the inkjet head 21A of the upper printing unit 4 described above.

The ink circulation mechanism 22B supplies ink to the inkjet head 21B while circulating the ink. The ink circulation mechanism 22B includes a pressurized tank (corresponding to a tank) 31B, a pressurized tank liquid level sensor 32B, a negative pressure tank (corresponding to a tank) 33B, a negative pressure tank liquid level sensor 34B, and an ink bath 35B. 36B, inflow pipe 37B, outflow pipe 38B, ink circulation pipes 39B to 41B, ink circulation pump 42B, buffer tank 43B, buffer tank liquid level sensor 44B, buffer tank air release valve 45B, and buffer tank. It includes an air release pipe 46B, an air filter 47B, an ink supply valve 48B, and a connection pipe 49B.

Pressurized tank 31B of ink circulation mechanism 22B, pressurized tank liquid level sensor 32B, negative pressure tank 33B, negative pressure tank liquid level sensor 34B, ink bath 35B, 36B, inflow pipe 37B, outflow pipe 38B, ink circulation pipe 39B ~ The 41B, the ink circulation pump 42B, the ink tank 43B, the buffer tank liquid level sensor 44B, the buffer tank open-air valve 45B, the buffer tank open-air pipe 46B, the air filter 47B, the ink supply valve 48B, and the connecting pipe 49B are described above. Pressurized tank 31A of ink circulation mechanism 22A, pressurized tank liquid level sensor 32A, negative pressure tank 33A, negative pressure tank liquid level sensor 34A, ink bath 35A, 36A, inflow pipe 37A, outflow pipe 38A, ink circulation pipe 39A ~ 41A, ink circulation pump 42A, ink tank 43A, buffer tank liquid level sensor 44A, buffer tank open-air valve 45A, buffer tank open-air pipe 46A, air filter 47A, ink supply valve 48A, and connection pipe 49A. be.

The ink supply unit 6 includes an ink cartridge (corresponding to a discharge ink storage unit) 51, a cartridge valve 52, an ink filter 53, ink supply pumps 54A and 54B, a common ink supply pipe 55, and individual ink supply pipes 56A. It includes 56B, ink return valves 57A and 57B, and ink return tubes 58A and 58B.

The ink cartridge 51 contains ink used for printing by the inkjet head 21. Further, the ink cartridge 51 receives and stores the ink discharged from the upper printing unit 4 and the lower printing unit 5 due to the ink removal described later. The ink cartridge 51 is arranged at a position (lower) lower than the lower printing unit 5. The ink cartridge 51 is always open to the atmosphere.

The cartridge valve 52 opens and closes the ink flow path in the common ink supply pipe 55.

The ink filter 53 removes dust and the like in the ink flowing through the common ink supply tube 55.

The ink supply pumps 54A and 54B send ink from the ink cartridge 51 to the buffer tanks 43A and 43B, respectively. The ink supply pump 54A is also used to send ink from the buffer tank 43B to the buffer tank 43A when the ink is drained, which will be described later. The ink supply pumps 54A and 54B are arranged in the individual ink supply pipes 56A and 56B, respectively.

The common ink supply tube 55 constitutes a common portion between the ink path between the ink cartridge 51 and the buffer tank 43A and the ink path between the ink cartridge 51 and the buffer tank 43B. One end of the common ink supply tube 55 is inserted into the ink cartridge 51, and the other end is connected to the individual ink supply tubes 56A and 56B.

The individual ink supply pipes 56A and 56B connect the buffer tanks 43A and 43B and the common ink supply pipe 55, respectively.

The ink return valves 57A and 57B open and close the ink flow path in the ink return tubes 58A and 58B, respectively.

The ink return tube 58A forms a part of the ink flow path that flows from the buffer tank 43A to the ink cartridge 51 when the ink is drained, which will be described later. One end of the ink return pipe 58A is inserted into the buffer tank 43A, and the other end is connected between the end of the individual ink supply pipe 56A on the common ink supply pipe 55 side and the ink supply pump 54A. The ink return tube 58B forms a part of the ink flow path that flows from the buffer tank 43B to the ink cartridge 51 when the ink is drained, which will be described later. One end of the ink return tube 58B is inserted into the buffer tank 43B, and the other end is connected between the end of the individual ink supply tube 56B on the common ink supply tube 55 side and the ink supply pump 54B.

The pressure generation unit 7 includes a pressurization common air chamber 61, a pressurization airtight valve 62A, 62B, a pressurization communication pipe 63A, 63B, a pressurization air pump 64, a pressurization pressure generation pipe 65, and a pressurization pressure adjustment. Valve 66, pressure pressure adjusting pipe 67, pressure pressure sensor 68, negative pressure common air chamber 69, negative pressure closed valves 70A, 70B, negative pressure communication pipes 71A, 71B, negative pressure air pump 72. , Atmospheric communication pipe 73, air filter 74, negative pressure pressure adjustment valve 75, negative pressure pressure adjustment pipe 76, negative pressure pressure sensor 77, applied pressure communication valve 78, and applied pressure communication pipe 79. To prepare for.

The pressurized common air chamber 61 is an air chamber for equalizing the pressures of the pressure tank 31A of each upper printing unit 4 and the pressure tank 31B of each lower printing unit 5. The pressurized common air chamber 61 is provided with the pressurized communication pipe 63A corresponding to each upper printing unit 4 and the pressurized communication pipe 63B corresponding to each lower printing unit 5 to the pressure tank 31A of each upper printing unit 4. And is connected to the pressure tank 31B of each lower printing unit 5.

The pressure sealing valve 62A switches communication and shutoff between the pressure common air chamber 61 and the pressure tank 31A of the upper printing unit 4 by opening and closing the air flow path in the pressure communication pipe 63A. The pressure sealing valve 62A is provided corresponding to each upper printing unit 4 one by one. Note that FIG. 2 shows only the pressure sealing valve 62A corresponding to one upper printing unit 4, and omits the illustration of the other pressure sealing valve 62A.

The pressure sealing valve 62B switches communication and shutoff between the pressure common air chamber 61 and the pressure tank 31B of the lower printing unit 5 by opening and closing the air flow path in the pressure communication pipe 63B. .. The pressure sealing valve 62B is provided corresponding to each lower printing unit 5. Note that FIG. 2 shows only the pressure sealing valve 62B corresponding to one lower printing unit 5, and omits the illustration of the other pressure sealing valve 62B.

The pressurized communication pipe 63A communicates the pressurized common air chamber 61 with the air layer of the pressurized tank 31A of the upper printing unit 4. A pressurized communication pipe 63A is provided corresponding to each upper printing unit 4. One end of the pressurized communication pipe 63A is connected to the pressurized common air chamber 61, and the other end is connected to the air layer of the pressurized tank 31A.

The pressurized communication pipe 63B communicates the pressurized common air chamber 61 with the air layer of the pressurized tank 31B of the lower printing unit 5. One pressure communication pipe 63B is provided corresponding to each lower printing unit 5. One end of the pressurized communication pipe 63B is connected to a portion between the pressurized common air chamber 61 and the pressurized closed valve 62A of the pressurized communication pipe 63A, and the other end is connected to the air layer of the pressure tank 31B. There is. Note that FIG. 2 shows only the pressurized communication pipe 63B corresponding to one lower printing unit 5, and omits the illustration of the other pressurized communication pipe 63B.

The pressurized air pump 64 sends air to the pressurized common air chamber 61 in order to apply a positive pressure to the pressurized tanks 31A and 31B. The pressurized air pump 64 is arranged in the middle of the pressurized pressure generation pipe 65.

The pressurized pressure generation pipe 65 forms an air flow path for sending air to the pressurized common air chamber 61 by the pressurized air pump 64. One end of the pressurized pressure generation pipe 65 is connected to the pressurized common air chamber 61, and the other end is connected to a portion of the atmospheric communication pipe 73 between the negative pressure air pump 72 and the air filter 74.

The pressurizing pressure adjusting valve 66 opens and closes the air flow path in the pressurizing pressure adjusting pipe 67 in order to adjust the pressures of the pressurizing common air chamber 61 and the pressurizing tanks 31A and 31B.

The pressurizing pressure adjusting pipe 67 forms an air flow path for adjusting the pressure of the pressurizing common air chamber 61 and the pressurizing tanks 31A and 31B. One end of the pressurized pressure adjusting pipe 67 is connected to the pressurized common air chamber 61, and the other end is connected to a portion of the atmospheric communication pipe 73 between the negative pressure air pump 72 and the air filter 74.

The pressurizing pressure sensor 68 detects the pressure in the pressurizing common air chamber 61. The pressure in the pressurizing common air chamber 61 is equal to the pressure of the pressurizing tanks 31A and 31B when the pressurizing sealing valves 62A and 62B are open.

The negative pressure common air chamber 69 is an air chamber for equalizing the pressures of the negative pressure tank 33A of each upper printing unit 4 and the negative pressure tank 33B of each lower printing unit 5. The negative pressure common air chamber 69 passes through the negative pressure communication pipe 71A corresponding to each upper printing unit 4 and the negative pressure communication pipe 71B corresponding to each lower printing unit 5, and the negative pressure tank 33A of each upper printing unit 4 And is connected to the negative pressure tank 33B of each lower printing unit 5.

The negative pressure sealing valve 70A switches the communication and shutoff between the negative pressure common air chamber 69 and the negative pressure tank 33A of the upper printing unit 4 by opening and closing the air flow path in the negative pressure communication pipe 71A. A negative pressure sealing valve 70A is provided corresponding to each upper printing unit 4. Note that FIG. 2 shows only the negative pressure sealing valve 70A corresponding to one upper printing unit 4, and omits the illustration of the other negative pressure sealing valve 70A.

The negative pressure sealing valve 70B switches the communication and shutoff between the negative pressure common air chamber 69 and the negative pressure tank 33B of the lower printing unit 5 by opening and closing the air flow path in the negative pressure communication pipe 71B. .. A negative pressure sealing valve 70B is provided corresponding to each lower printing unit 5. In FIG. 2, only the negative pressure sealing valve 70B corresponding to one lower printing unit 5 is shown, and the other negative pressure sealing valve 70B is not shown.

The negative pressure communication pipe 71A communicates the negative pressure common air chamber 69 with the air layer of the negative pressure tank 33A of the upper printing unit 4. One negative pressure communication pipe 71A is provided for each upper printing unit 4. One end of the negative pressure communication pipe 71A is connected to the negative pressure common air chamber 69, and the other end is connected to the air layer of the negative pressure tank 33A.

The negative pressure communication pipe 71B communicates the negative pressure common air chamber 69 with the air layer of the negative pressure tank 33B of the lower printing unit 5. One negative pressure communication pipe 71B is provided for each lower printing unit 5. One end of the negative pressure communication pipe 71B is connected to a portion between the negative pressure common air chamber 69 and the negative pressure sealing valve 70A of the negative pressure communication pipe 71A, and the other end is connected to the air layer of the negative pressure tank 33B. There is. Note that FIG. 2 shows only the negative pressure communication pipe 71B corresponding to one lower printing unit 5, and omits the illustration of the other negative pressure communication pipe 71B.

The negative pressure air pump 72 sucks air from the negative pressure common air chamber 69 in order to apply a negative pressure to the negative pressure tanks 33A and 33B. The negative pressure air pump 72 is arranged in the middle of the atmospheric communication pipe 73.

The atmospheric communication pipe 73 forms an air flow path for sucking air from the negative pressure common air chamber 69 by the negative pressure air pump 72. One end of the atmospheric communication pipe 73 is connected to the negative pressure common air chamber 69, and the other end (open end to the atmosphere) is connected to the atmosphere through the air filter 74. A pressure pressure generating pipe 65, a pressure pressure adjusting pipe 67, and a negative pressure pressure adjusting pipe 76 are connected to the atmosphere communication pipe 73. As a result, the pressurized pressure generating pipe 65, the pressurized pressure adjusting pipe 67, and the negative pressure pressure adjusting pipe 76 are communicated with the atmosphere.

The air filter 74 prevents dust and the like in the air from entering the atmospheric communication pipe 73. The air filter 74 is installed at the open end of the atmospheric communication pipe 73.

The negative pressure pressure adjusting valve 75 opens and closes the air flow path in the negative pressure adjusting pipe 76 in order to adjust the pressure of the negative pressure common air chamber 69 and the negative pressure tanks 33A and 33B.

The negative pressure pressure adjusting pipe 76 forms an air flow path for pressure adjustment of the negative pressure common air chamber 69 and the negative pressure tanks 33A and 33B. One end of the negative pressure adjusting pipe 76 is connected to the negative pressure common air chamber 69, and the other end is connected to a portion of the atmospheric communication pipe 73 between the negative pressure air pump 72 and the air filter 74.

The negative pressure pressure sensor 77 detects the pressure in the negative pressure common air chamber 69. The pressure in the negative pressure common air chamber 69 is equal to the pressure of the negative pressure tanks 33A and 33B when the negative pressure sealing valves 70A and 70B are open.

The negative pressure communication valve 78 opens and closes the air flow path in the negative pressure communication pipe 79 in order to switch communication and shutoff between the pressurized common air chamber 61 and the negative pressure common air chamber 69.

The negative pressure communication pipe 79 forms an air flow path for communicating the pressurized common air chamber 61 and the negative pressure common air chamber 69. One end of the negative pressure communication pipe 79 is connected to the pressurized common air chamber 61, and the other end is connected to the negative pressure common air chamber 69.

Next, the operation of the printing device 1 will be described.

When a print job is input, the control unit 9 closes the negative pressure communication valve 78. As a result, the space between the pressurized common air chamber 61 and the negative pressure common air chamber 69 is cut off. Further, the control unit 9 opens the cartridge valve 52.

In the printing device 1 in the standby state before the print job is input, the negative pressure communication valve 78 is open. Further, the pressure sealing valves 62A and 62B and the negative pressure sealing valves 70A and 70B are also open. The buffer tank atmosphere release valves 45A and 45B, the ink supply valves 48A and 48B, the cartridge valve 52, the ink return valves 57A and 57B, the pressurizing pressure adjusting valve 66, and the negative pressure pressure adjusting valve 75 are closed.

Next, the control unit 9 controls the pressurized air pump 64, the pressurized pressure adjusting valve 66, the negative pressure air pump 72, and the negative pressure pressure adjusting valve 75 to the pressurized tanks 31A and 31B and the negative pressure tanks 33A and 33B. Generate each set pressure. As a result, ink flows from the pressure tanks 31A and 31B to the negative pressure tanks 33A and 33B via the inkjet heads 21A and 21B in the upper printing unit 4 and the lower printing unit 5, respectively.

Here, the set pressures of the pressurized tanks 31A and 31B and the negative pressure tanks 33A and 33B are preset as pressure values for adjusting the nozzle pressures of the inkjet heads 21A and 21B to appropriate values while circulating the ink. It is a thing. The set pressures of the pressure tanks 31A and 31B are positive pressures, and the set pressures of the negative pressure tanks 33A and 33B are negative pressures.

When the set pressures of the pressurized tanks 31A and 31B and the negative pressure tanks 33A and 33B are generated, the control unit 9 starts executing the print job. Specifically, the control unit 9 ejects ink from the inkjet heads 21A and 21B to the web W conveyed by the transfer unit 3 based on the print job to print an image.

During this printing operation, the control unit 9 has a pressurized air pump 64, a pressurized pressure adjusting valve 66, and a negative pressure air pump so as to maintain the pressures of the pressurized tanks 31A and 31B and the negative pressure tanks 33A and 33B at their respective set pressures. 72 and the negative pressure pressure regulating valve 75 are controlled.

Further, during the printing operation, the control unit 9 performs liquid level maintenance control. The liquid level maintenance control is a control for circulating ink while maintaining the liquid level heights of the pressurized tanks 31A and 31B, the negative pressure tanks 33A and 33B, and the buffer tanks 43A and 43B at the reference height. In the liquid level maintenance control, the control unit 9 sets the ink circulation pump 42A, the ink supply valve 48A, and the ink supply pump 54A according to the liquid level heights of the pressure tank 31A, the negative pressure tank 33A, and the buffer tank 43A. Control. Further, the control unit 9 controls the ink circulation pump 42B, the ink supply valve 48B, and the ink supply pump 54B according to the liquid level heights of the pressure tank 31B, the negative pressure tank 33B, and the buffer tank 43B.

Specifically, in the upper printing unit 4, when both the pressure tank liquid level sensor 32A and the negative pressure tank liquid level sensor 34A are on, the control unit 9 turns off the ink circulation pump 42A and the ink supply valve 48A. To close. Similarly, even when the pressure tank liquid level sensor 32A is on and the negative pressure tank liquid level sensor 34A is off, the control unit 9 turns off the ink circulation pump 42A and closes the ink supply valve 48A.

When the pressure tank liquid level sensor 32A is off and the negative pressure tank liquid level sensor 34A is on, the control unit 9 turns on the ink circulation pump 42A and closes the ink supply valve 48A. As a result, the ink is sent from the negative pressure tank 33A to the pressure tank 31A.

When both the pressure tank liquid level sensor 32A and the negative pressure tank liquid level sensor 34A are off, the control unit 9 turns on the ink circulation pump 42A and opens the ink supply valve 48A. As a result, the ink is sent from the buffer tank 43A to the pressure tank 31A.

Further, when the buffer tank liquid level sensor 44A is off, the control unit 9 turns on the ink supply pump 54A. As a result, the ink is sent from the ink cartridge 51 to the buffer tank 43A. When the buffer tank liquid level sensor 44A is on, the control unit 9 turns off the ink supply pump 54A.

The liquid level maintenance control in the lower printing unit 5 is the same as the liquid level maintenance control in the upper printing unit 4 described above.

During the printing operation, ink is supplied from the pressure tank 31A to the inkjet head 21A in the upper printing unit 4, and the ink not consumed by the inkjet head 21A is collected in the negative pressure tank 33A. When the pressure tank liquid level sensor 32A is off and the negative pressure tank liquid level sensor 34A is on, the ink circulation pump 42A sends ink from the negative pressure tank 33A to the pressure tank 31A by the above-mentioned liquid level maintenance control. Liquid. Printing is performed while the ink is circulated in this way. The same applies to the lower printing unit 5.

Further, when both the pressure tank liquid level sensor 32A and the negative pressure tank liquid level sensor 34A are turned off in the upper printing unit 4, the ink circulation pump 42A pressurizes from the buffer tank 43A by the above-mentioned liquid level maintenance control. Ink is sent to the tank 31A. As a result, ink is replenished to the pressure tank 31A. The same applies to the lower printing unit 5.

Further, when the buffer tank liquid level sensor 44A is turned off in the upper printing unit 4, the ink supply pump 54A sends ink from the ink cartridge 51 to the buffer tank 43A by the liquid level maintenance control described above. As a result, ink is replenished to the buffer tank 43A. The same applies to the lower printing unit 5.

When the printing based on the print job is completed, the control unit 9 ends the liquid level maintenance control and the pressure control by the pressure generation unit 7, and shifts the printing device 1 to the standby state. This ends a series of operations.

Next, the operation of removing ink in the printing apparatus 1 will be described.

The ink removal is a process of removing the ink stored in the upper printing unit 4 and the lower printing unit 5. The ink removal is performed, for example, prior to the replacement of the inkjet head 21.

The printing apparatus 1 before the start of ink removal is in a standby state, and as described above, the negative pressure communication valves 78, the pressure sealing valves 62A and 62B, and the negative pressure sealing valves 70A and 70B are open. The buffer tank atmosphere release valves 45A and 45B, the ink supply valves 48A and 48B, the cartridge valve 52, the ink return valves 57A and 57B, the pressurizing pressure adjusting valve 66, and the negative pressure pressure adjusting valve 75 are closed. Further, the liquid level heights of the pressurized tanks 31A and 31B, the negative pressure tanks 33A and 33B, and the buffer tanks 43A and 43B are the respective reference heights.

3 and 4 are flowcharts for explaining the operation of ink removal. The processing of the flowcharts of FIGS. 3 and 4 is started when the operator who replaces the inkjet head 21 or the like instructs the start of ink removal by the operation of the operation input unit (not shown).

Here, in the processing of the flowcharts of FIGS. 3 and 4 described below, the processing for the upper printing unit 4, the lower printing unit 5, and the ink supply unit 6 is performed on all the upper printing units 4A to 4E and the lower printing unit. This is performed for the 5A to 5E and the ink supply units 6A to 6E.

In step S1 of FIG. 3, the control unit 9 opens the pressurizing pressure regulating valve 66 and closes the pressurizing sealing valve 62B and the negative pressure sealing valves 70A and 70B. As a result, the pressure tank 31A of the upper printing unit 4 is in an open state to the atmosphere, and the negative pressure tank 33A of the upper printing unit 4, the pressure tank 31B of the lower printing unit 5, and the negative pressure tank 33B are sealed. The buffer tanks 43A and 43B are in a sealed state.

Next, in step S2, the control unit 9 opens the ink supply valve 48A, the cartridge valve 52, and the ink return valve 57A.

As a result, the ink is started to be discharged from the upper printing unit 4. That is, due to the head difference between the pressure tank 31A and the ink cartridge 51, as shown in FIG. 5, the ink is ink from the pressure tank 31A via the inkjet head 21A, the negative pressure tank 33A, and the buffer tank 43A. Ink flows to the cartridge 51.

6 and 7 show the progress of ink being ejected from the upper printing unit 4. FIG. 6 shows a state after the ink is discharged from the pressure tank 31A and the inkjet head 21A. In this state, ink flows from the negative pressure tank 33A to the ink cartridge 51 via the buffer tank 43A due to the head difference between the negative pressure tank 33A and the ink cartridge 51. FIG. 7 shows a state after the ink is drained from the negative pressure tank 33A as well. In this state, ink flows from the buffer tank 43A to the ink cartridge 51 due to the water head difference between the buffer tank 43A and the ink cartridge 51.

While the ink is discharged from the upper printing unit 4, the ink is not discharged from the lower printing unit 5, and the ink is discharged only from the upper printing unit 4.

After the start of ink ejection from the upper printing unit 4, in step S3 of FIG. 3, the control unit 9 determines whether or not a predetermined upper ejection time has elapsed from the start of ink ejection from the upper printing unit 4. When it is determined that the upper discharge time has not elapsed since the start of ink discharge from the upper printing unit 4 (step S3: NO), the control unit 9 repeats step S3.

Here, the upper discharge time is a time set as the time required to remove the ink from the upper printing unit 4. The upper discharge time is set in advance based on experiments and the like.

When it is determined that the upper discharge time has elapsed from the start of ink discharge from the upper printing unit 4 (step S3: YES), in step S4, the control unit 9 closes the ink supply valve 48A and the ink return valve 57A. As a result, the ink is discharged from the upper printing unit 4.

Next, in step S5, the control unit 9 closes the pressure sealing valve 62A and opens the pressure sealing valve 62B. As a result, the pressure tank 31B of the lower printing unit 5 is open to the atmosphere, and the pressure tank 31A and the negative pressure tank 33A of the upper printing unit 4 and the negative pressure tank 33B of the lower printing unit 5 are sealed. .. The buffer tanks 43A and 43B are in a sealed state.

Next, in step S6, the control unit 9 opens the ink supply valve 48B and the ink return valve 57B.

As a result, the ink is started to be discharged from the lower printing unit 5. That is, due to the head difference between the pressure tank 31B and the ink cartridge 51, as shown in FIG. 8, the ink is ink from the pressure tank 31B via the inkjet head 21B, the negative pressure tank 33B, and the buffer tank 43B. Ink flows to the cartridge 51.

After the start of ink discharge from the lower printing unit 5, in step S7 of FIG. 3, the control unit 9 has elapsed a predetermined lower negative pressure tank discharge time from the start of ink discharge from the lower printing unit 5. Judge whether or not. When it is determined that the lower negative pressure tank discharge time has not elapsed from the start of ink discharge from the lower printing unit 5 (step S7: NO), the control unit 9 repeats step S7.

Here, the lower negative pressure tank discharge time is a time set as the time required to remove ink from the inkjet head 21B, the pressure tank 31B, and the negative pressure tank 33B of the lower printing unit 5. The lower negative pressure tank discharge time is set in advance based on experiments and the like.

When it is determined that the lower negative pressure tank discharge time has elapsed from the start of ink discharge from the lower printing unit 5 (step S7: YES), in step S8, the control unit 9 uses the pressurized airtight valve 62B and ink. The supply valve 48B and the cartridge valve 52 are closed.

Here, when the ink discharge time of the lower negative pressure tank has elapsed from the start of ink discharge from the lower printing unit 5, the ink is discharged from the inkjet head 21B, the pressure tank 31B, and the negative pressure tank 33B, and the buffer is buffered. The tank 43B is in a state in which the same amount of ink as at the start of ink removal is stored. Ink is also discharged from the ink baths 35B and 36B, the inflow pipe 37B, the outflow pipe 38B, and the ink circulation pipes 39B to 41B.

Next, in step S9, the control unit 9 opens the buffer tank atmospheric release valves 45A and 45B. As a result, the buffer tanks 43A and 43B are opened to the atmosphere.

Next, in step S10, the control unit 9 starts driving the ink supply pump 54A. As a result, as shown in FIG. 9, the ink is started to be sent from the buffer tank 43B of the lower printing unit 5 to the buffer tank 43A of the upper printing unit 4.

Returning to FIG. 3, in step S11, the control unit 9 determines whether or not a predetermined inter-buffer liquid transfer time has elapsed from the start of liquid transfer from the buffer tank 43B to the buffer tank 43A. When it is determined that the inter-buffer liquid transfer time has not elapsed since the start of liquid transfer from the buffer tank 43B to the buffer tank 43A (step S11: NO), the control unit 9 repeats step S11.

Here, the inter-buffer liquid transfer time is a time set as a time required to transfer all the ink in the buffer tank 43B to the buffer tank 43A. The liquid transfer time between buffers is set in advance based on experiments and the like.

When it is determined that the inter-buffer liquid transfer time has elapsed from the start of liquid transfer from the buffer tank 43B to the buffer tank 43A (step S11: YES), in step S12, the control unit 9 stops the ink supply pump 54A. Further, the control unit 9 closes the ink return valve 57B and the buffer tank atmosphere release valve 45B.

As a result, the ink transfer from the buffer tank 43B to the buffer tank 43A is completed. As a result, the ink in the buffer tank 43B is transferred to the buffer tank 43A.

Next, in step S13 of FIG. 4, the control unit 9 opens the ink return valve 57A and the cartridge valve 52. As a result, the ink is started to be discharged from the buffer tank 43A of the upper printing unit 4 to the ink cartridge 51. That is, due to the water head difference between the buffer tank 43A and the ink cartridge 51, ink flows from the buffer tank 43A to the ink cartridge 51 as shown in FIG.

Returning to FIG. 4, in step S14, the control unit 9 determines whether or not a predetermined buffer tank discharge time has elapsed from the start of ink discharge from the buffer tank 43A to the ink cartridge 51. When it is determined that the buffer tank discharge time has not elapsed since the start of ink discharge from the buffer tank 43A to the ink cartridge 51 (step S14: NO), the control unit 9 repeats step S14.

Here, the buffer tank discharge time is a time set as a time required to remove the ink transferred from the buffer tank 43B to the buffer tank 43A from the buffer tank 43A. The buffer tank discharge time is set in advance based on experiments and the like.

When it is determined that the buffer tank discharge time has elapsed from the start of ink discharge from the buffer tank 43A to the ink cartridge 51 (step S14: YES), in step S15, the control unit 9 controls the ink return valve 57A, the cartridge valve 52, and the ink cartridge valve 52. And close the buffer tank air release valve 45A.

When the buffer tank discharge time elapses from the start of ink discharge from the buffer tank 43A to the ink cartridge 51, the ink is discharged from the buffer tank 43A, and all the ink is discharged from the upper printing unit 4 and the lower printing unit 5. ..

Next, in step S16, the control unit 9 closes the pressurizing pressure adjusting valve 66 and opens the pressurizing sealing valves 62A and 62B and the negative pressure sealing valves 70A and 70B. This completes a series of ink removal operations.

As described above, in the ink removing operation, the printing apparatus 1 performs an operation of ejecting the ink of the upper printing unit 4 and the lower printing unit 5 to the ink cartridge 51 by using the head difference. Further, in this operation, the ink of the buffer tank 43B of the lower printing unit 5 is sent to the buffer tank 43A of the upper printing unit 4, and the ink is discharged from the buffer tank 43A to the ink cartridge 51 by using the head difference. Will be printed. Further, as is clear from the above description of the ink removal operation, the pressure regulating valve 66, the pressure sealing valve 62A, 62B, the negative pressure sealing valve 70A, 70B, the ink supply valve 48A, 48B, the cartridge valve 52, The ink return valves 57A and 57B and the ink supply pump 54A constitute a discharge operation unit.

As described above, in the printing apparatus 1, when the ink is removed from the upper printing unit 4 and the lower printing unit 5, the ink in the buffer tank 43B is sent to the buffer tank 43A, and the ink cartridge 51 is sent from the buffer tank 43A. The operation is performed by using the water head difference. As a result, the flow rate of the ink is larger than that of directly discharging the ink from the buffer tank 43B to the ink cartridge 51 due to the head difference, so that the time required for discharging is shortened. Therefore, according to the printing apparatus 1, the time required for ink removal can be shortened.

In the above-described embodiment, the case where all the inks in the upper printing unit 4 and the lower printing unit 5 are the targets of ejection in the ink removal has been described. That is, in the above-described embodiment, all the inks of the upper printing unit 4 and the lower printing unit 5 are discharged when the ink is removed. However, some inks may be ejected in each of the upper printing unit 4 and the lower printing unit 5. For example, only the inks of the buffer tanks 43A and 43B may be ejected.

Further, in the above-described embodiment, the ink in the buffer tank 43B, which is a part of the ink to be discharged from the lower printing unit 5, is sent to the buffer tank 43A. However, the buffer tank 43A is configured to have a sufficient capacity, and after the discharge of the ink to be discharged from the upper printing unit 4 is completed, all the ink to be discharged from the lower printing unit 5 is sent to the buffer tank 43A to be buffered. The ink cartridge 51 may be discharged from the tank 43A by using the water head difference. At least a part of the ink to be discharged from the lower printing unit 5 may be sent to the buffer tank 43A and discharged from the buffer tank 43A to the ink cartridge 51 by using the head difference. It is necessary to remove ink by discharging at least a part of the ink to be discharged from the lower printing unit 5 from the upper printing unit 4 having a larger head difference from the ink cartridge 51 than the lower printing unit 5. You can save time.

Further, the ink may be sent from the lower printing unit 5 to the buffer tank 43A before the ink is discharged from the upper printing unit 4. For example, when only the ink of the buffer tanks 43A and 43B is to be discharged, the buffer tank 43A does not overflow even if the ink of the buffer tank 43B is sent to the buffer tank 43A without discharging the ink of the buffer tank 43A. First, all the ink in the buffer tank 43B may be sent to the buffer tank 43A, and then the ink may be discharged from the buffer tank 43A to the ink cartridge 51 by using the water head difference.

Further, in the above-described embodiment, the inkjet printing apparatus 1 has been described, but other printing methods using ink may be used.

The present invention is not limited to the above-described embodiment as it is, and at the implementation stage, the components can be modified and embodied within a range that does not deviate from the gist thereof. In addition, various inventions can be formed by an appropriate combination of the plurality of components disclosed in the above-described embodiment. For example, some components may be removed from all the components shown in the embodiments.

[Additional Notes]
This application discloses the following inventions.

(Appendix 1)
The first printing unit, which stores ink and prints using the stored ink,
A second printing unit, which is arranged at a position lower than the first printing unit, stores ink, and prints using the stored ink.
The discharged ink storage unit located at a position lower than the second printing unit,
It is provided with a discharge operation unit that performs an operation of discharging the ink to be discharged in the first printing unit and the second printing unit to the discharge ink storage unit by using the head difference.
The discharge operation unit sends at least a part of the ink to be discharged in the second printing unit to the first printing unit, and utilizes the head difference from the first printing unit to the discharged ink storage unit. A printing device characterized by discharging the ink.

(Appendix 2)
The first printing unit and the second printing unit each have an inkjet head, a tank connected to the inkjet head to store ink, and a buffer tank connected to the tank to store ink.
The discharge operation unit is
After the ink of the inkjet head, the tank, and the buffer tank of the first printing unit is discharged to the discharged ink storage unit, the ink of the inkjet head, the tank, and the buffer tank of the second printing unit is discharged. Is discharged to the discharged ink storage unit.
At least a part of the ink of the inkjet head, the tank, and the buffer tank of the second printing unit is sent to the buffer tank of the first printing unit, and the buffer tank of the first printing unit is supplied. The printing apparatus according to Appendix 1, wherein the ink is discharged from the ink to the discharged ink storage unit by using a water head difference.

1 Printing device 2 Web roll support shaft 3 Transport section 4, 4A to 4E Upper printing section 5, 5A to 5E Lower printing section 6, 6A to 6E Ink supply section 7 Pressure generating section 8 Winding shaft 9 Control section 21,21A , 21B Inkjet head 22A, 22B Ink circulation mechanism 31A, 31B Pressurized tank 32A, 32B Pressurized tank liquid level sensor 33A, 33B Negative pressure tank 34A, 34B Negative pressure tank liquid level sensor 35A, 36A, 35B, 36B Ink bath 37A , 37B Inflow pipe 38A, 38B Outflow pipe 39A-41A, 39B-41B Ink circulation pipe 42A, 42B Ink circulation pump 43A, 43B Buffer tank 44A, 44B Buffer tank Liquid level sensor 45A, 45B Buffer tank Air release valve 46A, 46B Buffer Tank open to the atmosphere 47A, 47B, 74 Air filter 48A, 48B Ink supply valve 49A, 49B Connection tube 51 Ink cartridge 52 Cartridge valve 53 Ink filter 54A, 54B Ink supply pump 55 Common ink supply tube 56A, 56B Individual ink supply tube 57A , 57B Ink return valve 58A, 58B Ink return pipe 61 Pressurized common air chamber 62A, 62B Pressurized closed valve 63A, 63B Pressurized communication pipe 64 Pressurized air pump 65 Pressurized pressure generation pipe 66 Pressurized pressure adjusting valve 67 Pressurized Pressure adjustment pipe 68 Pressurized pressure sensor 69 Negative pressure common air chamber 70A, 70B Negative pressure closed valve 71A, 71B Negative pressure communication pipe 72 Negative pressure air pump 73 Atmospheric communication pipe 75 Negative pressure pressure adjustment valve 76 Negative pressure pressure adjustment pipe 77 Negative Pressure-pressure sensor 78 Pressure-pressurizing communication valve 79 Pressure-pressure communication pipe

Claims (2)

The first printing unit, which stores ink and prints using the stored ink,
A second printing unit, which is arranged at a position lower than the first printing unit, stores ink, and prints using the stored ink.
The discharged ink storage unit located at a position lower than the second printing unit,
It is provided with a discharge operation unit that performs an operation of discharging the ink to be discharged in the first printing unit and the second printing unit to the discharge ink storage unit by using the head difference.
The discharge operation unit sends at least a part of the ink to be discharged in the second printing unit to the first printing unit, and utilizes the head difference from the first printing unit to the discharged ink storage unit. A printing device characterized by discharging the ink. The first printing unit and the second printing unit each have an inkjet head, a tank connected to the inkjet head to store ink, and a buffer tank connected to the tank to store ink.
The discharge operation unit is
After the ink of the inkjet head, the tank, and the buffer tank of the first printing unit is discharged to the discharged ink storage unit, the ink of the inkjet head, the tank, and the buffer tank of the second printing unit is discharged. Is discharged to the discharged ink storage unit.
At least a part of the ink of the inkjet head, the tank, and the buffer tank of the second printing unit is sent to the buffer tank of the first printing unit, and the buffer tank of the first printing unit is supplied. The printing apparatus according to claim 1, wherein the ink is discharged from the ink to the discharged ink storage unit by using a water head difference.

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