JP7328818B2 - inkjet printer - Google Patents

Description

The present invention relates to an inkjet printing apparatus that performs printing by ejecting ink from an inkjet head.

2. Description of the Related Art In an inkjet printing apparatus, an inkjet head module including an inkjet head may be removed for replacement (see Patent Document 1).

When removing the inkjet head module, in order to prevent ink from dripping from the location where the inkjet head module was connected, a process of discharging ink from a path, tank, etc. connected to the inkjet head module is performed.

JP 2009-113212 A

When removing the inkjet head module, the process of discharging the ink described above takes a long time, which may increase the time required for removing the inkjet head module. There has been a demand for shortening the time required for this work.

SUMMARY OF THE INVENTION It is an object of the present invention to provide an inkjet printer capable of shortening the time required for removing an inkjet head module.

To achieve the above object, an inkjet printing apparatus of the present invention includes an inkjet head module including an inkjet head, a tank for storing ink, a path connecting the inkjet head module and the tank, and the inkjet head module. When the ink jet head module is removed, prior to the removal of the ink jet head module, the ink is removed from the tank so that the liquid surface height of the ink in the tank reaches a prescribed height at which the tank can receive the ink corresponding to the capacity of the path. and a control unit that executes ink discharge processing for discharging ink, and when the inkjet head module is removed from the path after the ink discharge processing, the ink in the path moves to the tank.

According to the inkjet printing apparatus of the present invention, since the ink is not completely discharged from the path, the tank, or the like connected to the inkjet head module, the time required for removing the inkjet head module can be shortened.

1 is a schematic configuration diagram of an inkjet printing apparatus according to an embodiment; FIG. 4 is a flowchart of ink discharge processing; FIG. 4 is an explanatory diagram of the flow of ink in the ink discharge process; FIG. 4 is an explanatory diagram of the flow of ink in the ink discharge process; FIG. 4 is an explanatory diagram of the state of the inkjet printing apparatus at the end of the ink discharge process; FIG. 4 is an explanatory diagram of ink flow when the inkjet head module is removed;

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, embodiments of the present invention will be described with reference to the drawings. The same or equivalent reference numerals are given to the same or equivalent parts and components throughout each drawing.

The embodiments shown below are examples of devices and the like for embodying the technical idea of this invention. are not specific to the following: The technical idea of this invention can be modified in various ways within the scope of claims.

FIG. 1 is a schematic configuration diagram of an inkjet printing apparatus according to an embodiment of the present invention. Note that the up-down direction in the following description is the vertical direction, and the up-down direction in FIG. 1 is the up-down direction.

As shown in FIG. 1, the inkjet printing apparatus 1 according to this embodiment includes a printing section 2, a pressure generating section 3, and a control section 4. As shown in FIG.

The printing unit 2 performs printing by ejecting ink onto a sheet conveyed by a conveying unit (not shown) while circulating the ink. The printing section 2 includes an inkjet head module 11, an ink circulation mechanism 12, an ink supply section 13, and air conduits 14-16.

The inkjet head module 11 ejects ink supplied by the ink circulation mechanism 12 . The inkjet head module 11 includes an inkjet head 21 , an inflow pipe 22 and an outflow pipe 23 .

The inkjet head 21 includes a plurality of nozzles that eject ink, a chamber that stores the ink that is ejected from the nozzles, and a plurality of piezoelectric elements (none of which are shown) that are arranged in the chamber and eject the ink from the nozzles. Prepare. The nozzles are open on a nozzle surface 21a, which is the lower surface of the inkjet head 21. As shown in FIG.

The inflow pipe 22 forms an ink flow path for causing the ink supplied from the ink circulation unit 12 to flow into the inkjet head 21 . The inflow pipe 22 connects the inkjet head 21 and an ink bus 33, which will be described later.

The outflow pipe 23 forms a flow path for ink that flows out from the inkjet head 21 without being consumed by the inkjet head 21 and returns to the ink circulation section 12 . The outflow pipe 23 connects the inkjet head 21 and an ink bus 34, which will be described later.

The ink circulation mechanism 12 supplies ink to the inkjet head module 11 while circulating the ink. The ink circulation mechanism 12 includes a pressure tank (corresponding to a tank) 31, a negative pressure tank (corresponding to a tank) 32, ink buses 33 and 34, ink circulation pipes 35 to 37, an ink circulation pump 38, an ink and a temperature detection unit 39 .

The pressure tank 31 stores ink to be supplied to the inkjet head module 11 . The ink in the pressurized tank 31 is supplied to the inkjet head module 11 via the ink circulation pipe 35 and the ink bus 33 . That is, the pressure tank 31 is arranged upstream of the inkjet head module 11 in the ink circulation direction. An air layer 41 is formed on the surface of the ink in the pressure tank 31 .

The pressure tank 31 is provided with a pressure tank liquid level sensor 42 . The pressure tank liquid level sensor 42 detects whether or not the liquid level of the ink in the pressure tank 31 has reached a reference level. The pressurized tank liquid level sensor 42 outputs a signal indicating "ON" when the liquid level in the pressurized tank 31 is equal to or higher than the reference height, and outputs "OFF" when the liquid level is lower than the reference height. output a signal indicating

The negative pressure tank 32 stores the ink returned without being consumed by the inkjet head module 11 . That is, the negative pressure tank 32 is arranged downstream of the inkjet head module 11 in the ink circulation direction. An air layer 46 is formed on the surface of the ink in the negative pressure tank 32 .

A negative pressure tank liquid level sensor 47 is provided in the negative pressure tank 32 . The negative pressure tank liquid level sensor 47 detects whether the liquid level of ink in the negative pressure tank 32 has reached a reference level. The negative pressure tank liquid level sensor 47 outputs a signal indicating "ON" when the liquid level in the negative pressure tank 32 is equal to or higher than the reference height, and outputs "OFF" when the liquid level is lower than the reference height. output a signal indicating

The ink bus 33 supplies the ink sent from the pressure tank 31 through the ink circulation pipe 35 to the inkjet head module 11 . The ink bus 33 and the ink circulation pipe 35 constitute a pressurized ink path 48 that connects the inkjet head module 11 and the pressurized tank 31 .

The ink bus 34 collects ink that has not been consumed by the inkjet head module 11 and flows it to the ink circulation pipe 36 . The ink bus 34 and the ink circulation pipe 36 constitute a negative pressure ink path 49 that connects the inkjet head module 11 and the negative pressure tank 32 .

The ink circulation pipe 35 connects the pressure tank 31 and the ink bus 33 . An ink circulation pipe 36 connects the ink bus 34 and the negative pressure tank 32 . The ink circulation pipe 37 connects the pressure tank 31 and the negative pressure tank 32 .

The ink circulation pump 38 sends ink from the negative pressure tank 32 to the pressure tank 31 through the ink circulation pipe 37 during ink circulation. Further, when ink is supplied from the ink supply unit 13 to the ink circulation mechanism 12 , the ink circulation pump 38 pumps ink from the buffer tank 51 (described later) to the pressure tank 31 via a part of the connection pipe 53 and the ink circulation pipe 37 (described later). Send ink to

The ink temperature detection section 39 detects the temperature of ink in the printing section 2 . The ink temperature detector 39 is arranged in the ink circulation pipe 37 . Note that the ink temperature detection unit 39 may be arranged at another position where the ink temperature can be detected.

The ink supply unit 13 supplies ink to the ink circulation mechanism 12 . The ink supply unit 13 includes a buffer tank 51, an ink supply valve 52, a connection pipe 53, an ink tank 54, an ink supply pump 55, an ink supply pipe 56, a buffer tank liquid level adjustment valve 57, and a bypass pipe. 58.

The buffer tank 51 stores ink to be supplied to the ink circulation mechanism 12 . The buffer tank 51 receives ink from the ink tank 54 and stores the supplied ink. An air layer 61 is formed on the ink surface in the buffer tank 51 . The buffer tank 51 is connected to the ink circulation pipe 37 via a connection pipe 53 . The buffer tank 51 is arranged at a position lower (lower) than the nozzle surface 21 a of the inkjet head 21 .

A buffer tank liquid level sensor 62 is provided in the buffer tank 51 . A buffer tank liquid level sensor 62 detects whether or not the liquid level of ink in the buffer tank 51 has reached a reference level. The buffer tank liquid level sensor 62 outputs a signal indicating "on" when the liquid level in the buffer tank 51 is equal to or higher than the reference height, and outputs a signal indicating "off" when it is less than the reference height. to output

The ink supply valve 52 opens and closes the ink flow path in the connection pipe 53 .

A connection pipe 53 connects the ink circulation pipe 37 and the buffer tank 51 . The connection pipe 53 has one end connected to the portion of the ink circulation pipe 37 between the negative pressure tank 32 and the ink circulation pump 38 and the other end connected to the buffer tank 51 .

The ink tank 54 contains ink used for printing by the inkjet head module 11 . The ink tank 54 is arranged at a lower position (below) than the pressure tank 31 , the negative pressure tank 32 and the buffer tank 51 . The ink tank 54 is always open to the atmosphere (connected to the atmosphere).

The ink supply pump 55 supplies ink from the ink tank 54 to the buffer tank 51 through the ink supply pipe 56 .

The buffer tank liquid level adjustment valve 57 opens and closes the ink flow path in the bypass pipe 58 .

The bypass pipe 58 constitutes a path that bypasses the ink supply pump 55 . The bypass pipe 58 has one end connected to the portion of the ink supply pipe 56 between the buffer tank 51 and the ink supply pump 55 and the other end connected to the portion of the ink supply pipe 56 between the ink supply pump 55 and the ink tank 54 . It is connected to the.

The air conduit 14 forms an air flow path between the pressurized tank 31 and the pressure generator 3 . The air conduit 14 has one end connected to the air layer 41 of the pressurized tank 31 and the other end connected to the pressure generator 3 .

The air conduit 15 forms an air flow path between the negative pressure tank 32 and the pressure generator 3 . The air conduit 15 has one end connected to the air layer 46 of the negative pressure tank 32 and the other end connected to the pressure generator 3 .

The air conduit 16 forms an air flow path between the buffer tank 51 and the pressure generator 3 . The air conduit 16 has one end connected to the air layer 61 of the buffer tank 51 and the other end connected to the pressure generator 3 .

The pressure generation unit 3 generates pressure for ink circulation in the pressure tank 31 and the negative pressure tank 32 of the printing unit 2 . In addition, the pressure generator 3 switches the buffer tank 51 between a sealed state (a state cut off from the atmosphere) and an atmosphere open state.

The pressure generator 3 includes a pressurization pressure adjustment mechanism for adjusting the pressure in the pressurization tank 31 and a negative pressure adjustment mechanism for adjusting the pressure in the negative pressure tank 32 (both not shown). Prepare. The pressure generator 3 also includes a pressurization pressure sensor that detects the pressure in the pressurization tank 31 and a negative pressure sensor that detects the pressure in the negative pressure tank 32 (both not shown).

The pressure generating unit 3 also includes a pressurized atmosphere open valve that switches the pressurized tank 31 between a closed state and an open to the atmosphere state, and a negative pressure atmosphere valve that switches the negative pressure tank 32 between a closed state and an open to the atmosphere state. A release valve (neither shown) is provided.

The pressure generator 3 also includes a pressurization/relief pressure communication valve (not shown) for switching communication between the air layer 41 of the pressurized tank 31 and the air layer 46 of the negative pressure tank 32 .

The pressure generator 3 also includes a buffer tank atmosphere release valve (not shown) that switches the buffer tank 51 between a closed state and an atmosphere open state.

The control section 4 controls the operation of each section of the inkjet printer 1 . The control unit 4 includes a CPU, RAM, ROM, hard disk, and the like.

During printing, the control unit 4 controls the printing unit 2 and the pressure generating unit 3 so that ink is ejected from the inkjet head module 11 while circulating the ink in the ink circulation unit 12 .

Further, when the inkjet head module 11 is removed for replacement, the control unit 4 executes an ink discharge process, which will be described later, prior to the removal of the inkjet head module 11 .

Next, the operation of the inkjet printer 1 will be described.

When a print job is input, the control section 4 disconnects the air layer 41 of the pressure tank 31 and the air layer 46 of the negative pressure tank 32 .

Note that in the inkjet printing apparatus 1 in a standby state before a print job is input, the air layer 41 of the pressure tank 31 and the air layer 46 of the negative pressure tank 32 are in communication. Also, the pressurized tank 31, the negative pressure tank 32, and the buffer tank 51 are in a sealed state. Also, the ink supply valve 52 and the buffer tank liquid level adjustment valve 57 are closed.

Next, the control unit 4 controls the pressure generation unit 3 to generate the respective set pressures in the pressurization tank 31 and the negative pressure tank 32 . As a result, ink flows from the pressurized tank 31 to the negative pressure tank 32 via the inkjet head module 11 . Here, the set pressure of each of the pressure tank 31 and the negative pressure tank 32 is set in advance as a pressure value for setting the nozzle pressure of the inkjet head 21 to an appropriate value while circulating the ink. The set pressure of the pressurization tank 31 is positive pressure, and the set pressure of the negative pressure tank 32 is negative pressure.

When the respective set pressures are generated in the pressurization tank 31 and the negative pressure tank 32, the control section 4 starts executing the print job. Specifically, based on the print job, the control unit 4 causes the inkjet head 21 to eject ink onto a sheet conveyed by a conveying unit (not shown) to print an image.

During this printing operation, the control unit 4 controls the pressure generation unit 3 to maintain the pressures of the pressurization tank 31 and the negative pressure tank 32 at their respective set pressures.

Further, during the printing operation, the control unit 4 performs liquid level maintenance control. The liquid level maintenance control is a control for ink circulation while maintaining the liquid levels of the pressure tank 31, the negative pressure tank 32, and the buffer tank 51 at the reference level. In the liquid level maintenance control, the control unit 4 operates the ink circulation pump 38, the ink supply valve 52, and the ink supply pump 55 according to the liquid level heights of the pressure tank 31, the negative pressure tank 32, and the buffer tank 51. Control.

Specifically, when both the pressure tank liquid level sensor 42 and the negative pressure tank liquid level sensor 47 are on, the controller 4 turns off the ink circulation pump 38 and closes the ink supply valve 52 . Similarly, even when the pressure tank liquid level sensor 42 is on and the negative pressure tank liquid level sensor 47 is off, the control section 4 turns off the ink circulation pump 38 and closes the ink supply valve 52 .

When the pressure tank liquid level sensor 42 is off and the negative pressure tank liquid level sensor 47 is on, the controller 4 turns on the ink circulation pump 38 and closes the ink supply valve 52 . As a result, ink is sent from the negative pressure tank 32 to the pressure tank 31 .

When the pressure tank liquid level sensor 42 and the negative pressure tank liquid level sensor 47 are both off, the controller 4 turns on the ink circulation pump 38 and opens the ink supply valve 52 . As a result, the ink is sent from the buffer tank 51 to the pressure tank 31 .

When the buffer tank liquid level sensor 62 is off, the controller 4 turns on the ink supply pump 55 . As a result, the ink is sent from the ink tank 54 to the buffer tank 51 . When the buffer tank liquid level sensor 62 is on, the controller 4 turns off the ink supply pump 55 .

During the printing operation, ink is supplied from the pressure tank 31 to the inkjet head module 11 , and the ink not consumed by the inkjet head module 11 is collected in the negative pressure tank 32 . When the pressure tank liquid level sensor 42 is turned off and the negative pressure tank liquid level sensor 47 is turned on, the ink circulation pump 38 sends ink from the negative pressure tank 32 to the pressure tank 31 by the liquid level maintenance control described above. liquid. Printing is performed while the ink is circulated in this manner.

When both the pressure tank liquid level sensor 42 and the negative pressure tank liquid level sensor 47 are turned off, the ink circulation pump 38 sends ink from the buffer tank 51 to the pressure tank 31 by the liquid level maintenance control described above. liquid. As a result, ink is supplied to the ink circulation mechanism 12 .

When the buffer tank liquid level sensor 62 is turned off, the ink supply pump 55 feeds the ink from the ink tank 54 to the buffer tank 51 by the liquid level maintenance control described above. As a result, the buffer tank 51 is replenished with ink.

When the printing based on the print job is completed, the control section 4 terminates the liquid level maintenance control and the pressure control by the pressure generation section 3, and shifts the inkjet printer 1 to the standby state. This completes the series of operations.

Next, the ink discharge process performed prior to the removal of the inkjet head module 11 when replacing the inkjet head module 11 will be described with reference to the flowchart of FIG. Replacement of the inkjet head module 11 is performed when the inkjet head module 11 breaks down.

The inkjet printing apparatus 1 is in a standby state before the start of the ink discharge process. and the air layer 46 of the negative pressure tank 32 are communicated. Also, the ink supply valve 52 and the buffer tank liquid level adjustment valve 57 are closed. Further, the liquid levels of the pressurized tank 31, the negative pressure tank 32, and the buffer tank 51 are set to a reference level.

The processing of the flowchart of FIG. 2 is started when the operator who performs the replacement work of the inkjet head module 11 operates an operation input unit (not shown) to instruct the start of the ink discharge processing.

In step S1 of FIG. 2, the control unit 4 controls the pressure generating unit 3 to switch the pressurized tank 31 from the sealed state to the atmosphere open state.

Next, in step S2, the controller 4 opens the ink supply valve 52 and the buffer tank liquid level adjustment valve 57. As shown in FIG.

As a result, outflow of ink from the pressure tank 31 is started. That is, due to the head difference between the pressure tank 31 and the ink tank 54, as shown in FIG. Ink flows into tank 54 . As the ink flows out from the pressure tank 31, the liquid surface of the ink in the pressure tank 31 is lowered.

Next, in step S<b>3 , the control unit 4 determines whether or not a predetermined pressurization-side outflow time has elapsed from the start of ink outflow from the pressurization tank 31 . When determining that the pressure-side outflow time has not elapsed (step S3: NO), the control section 4 repeats step S3.

Here, the pressurization-side outflow time is set as the outflow time of the ink from the pressure tank 31 so that the liquid level of the ink in the pressure tank 31 reaches the specified height Hk at the end of the ink discharge process. It is. The specified height Hk of the pressurized tank 31 is set as the liquid surface height at which the pressurized tank 31 can receive the ink corresponding to the volume of the pressurized ink path 48 . The specified height Hk is lower than the aforementioned reference height of the pressurized tank 31 .

The controller 4 adjusts the pressure-side outflow time based on the ink temperature detected by the ink temperature detector 39 . Specifically, the higher the temperature of the ink, the lower the viscosity of the ink, so the controller 4 shortens the pressure-side outflow time.

When it is determined that the pressurized side outflow time has elapsed (step S3: YES), in step S4, the controller 4 controls the pressure generator 3 to switch the pressurized tank 31 from the state open to the atmosphere to the sealed state, The negative pressure tank 32 is switched from the sealed state to the atmosphere open state.

As a result, the outflow of ink from the pressure tank 31 is stopped and the outflow of ink from the negative pressure tank 32 is started. That is, due to the head difference between the negative pressure tank 32 and the ink tank 54, ink flows from the negative pressure tank 32 to the ink tank 54 via the buffer tank 51, as shown in FIG. As the ink flows out from the negative pressure tank 32, the liquid surface of the ink in the negative pressure tank 32 is lowered.

Next, in step S<b>5 , the controller 4 determines whether or not a predetermined negative pressure side outflow time has elapsed from the start of ink outflow from the negative pressure tank 32 . When determining that the negative pressure side outflow time has not elapsed (step S5: NO), the control section 4 repeats step S5.

Here, the outflow time on the negative pressure side is set as the outflow time of ink from the negative pressure tank 32 so that the liquid level of the ink in the negative pressure tank 32 reaches the specified height Hf when the ink discharging process is completed. It is. The specified height Hf of the negative pressure tank 32 is set as the liquid surface height at which the negative pressure tank 32 can receive the ink corresponding to the capacity of the negative pressure ink path 49 . The prescribed height Hf is lower than the aforementioned reference height of the negative pressure tank 32 .

The control unit 4 adjusts the negative pressure side outflow time based on the ink temperature detected by the ink temperature detection unit 39 in the same manner as the pressure side outflow time.

If it is determined that the negative pressure side outflow time has elapsed (step S5: YES), the controller 4 closes the buffer tank liquid level adjustment valve 57 in step S6. As a result, the outflow of ink from the negative pressure tank 32 is stopped.

Next, in step S7, the controller 4 controls the pressure generator 3 to switch the buffer tank 51 from the closed state to the atmosphere open state. Further, the control unit 4 controls the pressure generating unit 3 so that the air layer 41 of the pressurization tank 31 and the air layer 46 of the negative pressure tank 32 are communicated with each other, and the negative pressure tank 32 is changed from the open state to the closed state. switch.

As a result, due to the head difference between the nozzle surface 21 a of the inkjet head 21 and the buffer tank 51 , ink begins to flow from the ink circulation mechanism 12 side to the buffer tank 51 . At this time, the ink flows between the two tanks through the pressurized ink path 48, the inkjet head module 11, and the negative pressure ink path 49 so that the liquid levels in the pressurized tank 31 and the negative pressure tank 32 are at the same level. Ink flows from the negative pressure tank 32 to the buffer tank 51 while moving. Thereby, negative pressure is generated in the pressurized tank 31 and the negative pressure tank 32 .

Next, in step S8, the controller 4 controls the pressure in the pressurized tank 31 and the negative pressure tank 32 to reach the specified negative pressure value based on the detected values of the pressurization pressure sensor and the negative pressure sensor of the pressure generator 3. determine whether it happened or not. When determining that the specified negative pressure value has not been reached (step S8: NO), the control section 4 repeats step S8.

Here, the specified negative pressure value is set as the pressure value in the pressure tank 31 and the negative pressure tank 32 at the end of the ink discharging process. When the inkjet head module 11 is removed, the pressure values in the pressure tank 31 and the negative pressure tank 32 at the end of the ink discharge process are such that the ink in the pressure ink path 48 and the negative pressure ink path 49 are pressurized respectively. A negative pressure is set so as to move to the tank 31 and the negative pressure tank 32 .

In this embodiment, the ink levels in the pressure tank 31 and the negative pressure tank 32 are higher than the nozzle surface 21a at the end of the ink discharge process. Further, the nozzle pressure at the end of the ink discharge process becomes the specified negative pressure value. On the other hand, the specified negative pressure value is set to be a value larger in absolute value than the hydraulic head pressure between the nozzle surface 21a and the pressure tank 31 and the negative pressure tank 32. FIG. As a result, ink leakage from the nozzles of the inkjet head 21 is suppressed.

Also, the specified negative pressure value is set to be a value smaller in absolute value than the meniscus breaking pressure in the nozzles of the inkjet head 21 . This prevents the meniscus of the nozzles of the ink jet head 21 from being destroyed and air from being sucked in from the nozzles.

If it is determined that the specified negative pressure value has been reached (step S8: YES), the controller 4 closes the ink supply valve 52 in step S9. As a result, the movement of ink from the ink circulation mechanism 12 side to the buffer tank 51 stops.

Next, in step S10, the controller 4 controls the pressure generator 3 to switch the buffer tank 51 from the open state to the closed state. This completes the ink discharge process.

At the end of the ink discharge process, as shown in FIG. 5, the liquid level of ink in the pressure tank 31 reaches a specified height Hk, and the liquid level of ink in the negative pressure tank 32 reaches a specified height. and Hf. Here, when the pressure tank 31 and the negative pressure tank 32 have the same shape and the capacity of the pressure ink path 48 and the capacity of the negative pressure ink path 49 are equal, the specified height Hk of the pressure tank 31 and the specified height Hf of the negative pressure tank 32 are equal.

At the end of the ink discharge process, the liquid surfaces of the ink in the pressure tank 31 and the negative pressure tank 32 are at the connection between the inkjet head module 11 and the pressurized ink path 48 and at the connection between the inkjet head module 11 and the negative pressure ink. It is located lower than the connecting portion with the path 49 . Specifically, at the end of the ink discharge process, the liquid surface of the ink in the pressure tank 31 and the negative pressure tank 32 is at the connection portion between the inflow pipe 22 and the ink bus 33 and at the connection portion between the outflow pipe 23 and the ink bus. It is located lower than the connecting portion with 34.

5, the pressurized ink path 48, the negative pressure ink path 49, the ink circulation pipe 37, the ink supply pipe 56, and the bypass pipe 58 are filled with ink.

After the ink discharge process is finished, when the inkjet head module 11 is removed from the pressurized ink path 48 and the negative pressure ink path 49, the negative pressure in the pressurized tank 31 and the negative pressure tank 32 causes the pressure as shown in FIG. , ink in the pressurized ink path 48 moves to the pressurized tank 31 , and ink in the negative pressure ink path 49 moves to the negative pressure tank 32 . This prevents ink from dripping from the pressurized ink path 48 and the negative pressure ink path 49 . Since the pressure tank 31 and the negative pressure tank 32 have their liquid levels lowered to the specified heights Hk and Hf by the ink discharge process, respectively, the ink from the pressure ink path 48 and the negative pressure ink path 49 flows into them. However, it never overflows.

Here, the liquid surface of the ink in the pressure tank 31 after it has been lowered to the specified height Hk by the ink discharge process is such that the ink corresponding to the capacity of the pressure ink path 48 after the removal of the inkjet head module 11 is removed from the pressure tank 31 . , the position is lower than the connecting portion between the inkjet head module 11 and the pressurized ink path 48 and the connecting portion between the inkjet head module 11 and the negative pressure ink path 49 . Moreover, it is desirable that the liquid level of the ink in the pressurized tank 31 is at the above-described reference height when ink reception of the pressurized ink path 48 is completed.

In addition, the liquid level of the ink in the negative pressure tank 32 after it has been lowered to the specified height Hf by the ink discharge process is such that the negative pressure tank 32 is filled with ink corresponding to the capacity of the negative pressure ink path 49 after the inkjet head module 11 is removed. Even during reception, it is at a position lower than the connecting portion between the inkjet head module 11 and the pressurized ink path 48 and the connecting portion between the inkjet head module 11 and the negative pressure ink path 49 . Further, it is desirable that the liquid level of the ink in the negative pressure tank 32 is at the above-mentioned reference height when ink reception of the negative pressure ink path 49 is completed.

As described above, in the inkjet printing apparatus 1, when the inkjet head module 11 is removed, the controller 4 controls the ink discharge process so that the liquid level of the ink in the pressure tank 31 and the negative pressure tank 32 is , the pressurized ink path 48 and the negative pressure ink path 49, respectively. 32 to drain the ink.

When the inkjet head module 11 is removed from the pressurized ink path 48 and the negative pressure ink path 49 after the ink discharge process is completed, the ink in the pressurized ink path 48 moves to the pressurized tank 31 and the negative pressure ink is discharged. Ink in path 49 moves to negative pressure tank 32 .

Therefore, it is not necessary to completely discharge ink from the pressure tank 31, the negative pressure tank 32, the pressure ink path 48, and the negative pressure ink path 49 prior to removing the inkjet head module 11. FIG. Therefore, in the ink discharging process of the inkjet printing apparatus 1, the required time is shortened compared to the process of completely discharging the ink in the pressure tank 31, the negative pressure tank 32, the pressure ink path 48, and the negative pressure ink path 49. can. As a result, according to the inkjet printing apparatus 1, the time required for the work for removing the inkjet head module 11 can be shortened.

In the ink jet printer 1 , the ink discharged from the pressure tank 31 and the negative pressure tank 32 moves to the buffer tank 51 in the ink discharge process. Therefore, in the inkjet printing apparatus 1 that circulates ink between the pressure tank 31, the inkjet head module 11, and the negative pressure tank 32, the ink discharge process is executed without wasting the ink. It is possible to shorten the time required for the work for removing the.

Further, in the inkjet printing apparatus 1, the specified negative pressure value, which is the pressure value in the pressure tank 31 and the negative pressure tank 32 at the end of the ink discharge process, is the nozzle surface 21a, the pressure tank 31 and the negative pressure tank 32. It is set to a value larger in absolute value than the head pressure between As a result, ink leakage from the nozzles of the inkjet head 21 is suppressed even when the ink levels in the pressure tank 31 and the negative pressure tank 32 are higher than the nozzle surface 21a at the end of the ink discharge process. be done.

Further, in the inkjet printing apparatus 1, at the end of the ink discharge process, the liquid surface of the ink in the pressure tank 31 and the negative pressure tank 32 reaches the connection portion between the inkjet head module 11 and the pressurized ink path 48, and It is positioned lower than the connecting portion between the inkjet head module 11 and the negative pressure ink path 49 . As a result, even if negative pressure is not generated in the pressure tank 31 and the negative pressure tank 32 due to a problem, the ink in the pressure ink path 48 moves to the pressure tank 31 when the inkjet head module 11 is removed. Then, the ink in the negative pressure ink path 49 moves to the negative pressure tank 32 . Therefore, dripping of ink from the pressurized ink path 48 and the negative pressure ink path 49 can be suppressed more reliably.

In the above-described embodiment, when the inkjet head module 11 is removed, the ink in the pressurized ink path 48 and the negative pressure ink path 49 is transferred to the pressurized ink path 31 and the negative pressure tank 32 by negative pressure. Although the example of pulling in has been described, the present invention is not limited to this. For example, if the pressure tank 31 and the negative pressure tank 32 are positioned lower than the inkjet head module 11 and the inkjet head module 11 is removed, the connecting portion between the inkjet head module 11 and the pressurized ink path 48 and the pressurized tank 31 will be closed. The ink in the pressurized ink path 48 moves to the pressurized tank 31 due to the head difference between the pressure ink path 48 and the negative pressure ink path The ink in 49 may move to the negative pressure tank 32 .

In the above-described embodiment, two tanks, the pressure tank 31 and the negative pressure tank 32, are connected to the inkjet head module 11, and the pressure tank 31, the inkjet head module 11, and the negative pressure tank 32 are connected to each other. The inkjet printing apparatus 1 with ink circulation has been described. However, the present invention can also be applied to a configuration in which ink is circulated between one tank connected to the inkjet head module 11 and the inkjet head module 11 .

Further, in the above-described embodiment, the configuration in which the inkjet head module 11 including the inkjet head 21, the inflow pipe 22, and the outflow pipe 23 is removed from the ink buses 33 and 34 has been described. However, not limited to this, for example, the inkjet head module may include the inkjet head 21, the inflow pipe 22, the outflow pipe 23, and the ink buses 33 and 34, and the inkjet head module may be removed from the ink circulation pipes 35 and 36. There may be. Also, for example, the inkjet head module includes the inkjet head 21, the inflow pipe 22, the outflow pipe 23, the ink buses 33 and 34, and a portion of the ink circulation pipes 35 and 36. may be configured to be detached from the rest of the Alternatively, for example, the inkjet head module may be composed of only the inkjet head 21 and the inkjet head 21 may be removed from the inflow pipe 22 and the outflow pipe 23 . The inkjet head module may be any detachable unit including the inkjet head 21 .

The present invention is not limited to the above-described embodiment as it is, and can be embodied by modifying the constituent elements without departing from the gist of the present invention. Also, various inventions can be formed by appropriate combinations of the plurality of constituent elements disclosed in the above embodiments. For example, some components may be deleted from all the components shown in the embodiments.

[Appendix]
This application discloses the following inventions.

(Appendix 1)
an inkjet head module including an inkjet head;
a tank for storing ink;
a path connecting the inkjet head module and the tank;
When the inkjet head module is removed, prior to the removal of the inkjet head module, the liquid level of the ink in the tank is set to a specified height at which the tank can receive the ink corresponding to the capacity of the path. a control unit that executes an ink discharge process for discharging ink from the tank;
An inkjet printing apparatus according to claim 1, wherein when the inkjet head module is removed from the path after the ink discharging process, the ink in the path moves to the tank.

(Appendix 2)
the liquid level of the ink in the tank at the end of the ink discharging process is at a position higher than the nozzle surface of the inkjet head;
The inkjet printing apparatus according to Supplementary Note 1, wherein a negative pressure larger in absolute value than a water head pressure between the nozzle surface and the tank is generated in the tank at the end of the ink discharge process. .

(Appendix 3)
3. The inkjet printing apparatus according to appendix 1 or 2, wherein the liquid level of the ink in the tank at the end of the ink discharge process is at a position lower than the connecting portion between the inkjet head module and the path. .

(Appendix 4)
The inkjet head module is connected to the two tanks by the two paths connected to each of the two tanks, and a buffer tank is connected to the two tanks,
one of the two tanks stores ink to be supplied to the inkjet head module;
the other of the two tanks stores the ink returned from the inkjet head module;
4. The inkjet printing apparatus according to any one of appendices 1 to 3, wherein in the ink discharging process, the ink discharged from the two tanks is moved to the buffer tank.

REFERENCE SIGNS LIST 1 inkjet printer 2 printing unit 3 pressure generation unit 4 control unit 11 inkjet head module 12 ink circulation mechanism 13 ink supply unit 21 inkjet head 21a nozzle surface 22 inflow pipe 23 outflow pipe 31 pressure tank 32 negative pressure tank 33, 34 ink Buses 35 to 37 Ink circulation pipe 38 Ink circulation pump 48 Pressurized ink path 49 Negative pressure ink path 51 Buffer tank 52 Ink supply valve 53 Connection pipe 54 Ink tank 55 Ink supply pump 56 Ink supply pipe 57 Buffer tank liquid level adjustment valve 58 Bypass pipe

Claims (5)

an inkjet head module including an inkjet head;
a tank for storing ink;
a path connecting the inkjet head module and the tank;
When the inkjet head module is removed, prior to the removal of the inkjet head module, the liquid level of the ink in the tank is set to a specified height at which the tank can receive the ink corresponding to the capacity of the path. a control unit that executes an ink discharge process for discharging ink from the tank;
When the inkjet head module is removed from the path after the ink discharging process, the ink in the path moves to the tank,
The specified height is the liquid level height of the ink in the tank when ink for the capacity of the path has been received after the inkjet head module is removed, and the liquid level height before the start of the ink discharge process. An inkjet printing device, characterized in that it is set to be an inkjet head module including an inkjet head;
a tank for storing ink;
a path connecting the inkjet head module and the tank;
When the inkjet head module is removed, prior to the removal of the inkjet head module, the liquid level of the ink in the tank is set to a specified height at which the tank can receive the ink corresponding to the capacity of the path. a control unit that executes an ink discharge process for discharging ink from the tank;
the liquid level of the ink in the tank at the end of the ink discharging process is at a position higher than the nozzle surface of the inkjet head;
At the end of the ink discharge process, a negative pressure greater in absolute value than a water head pressure between the nozzle surface and the tank is generated in the tank,
An inkjet printing apparatus according to claim 1, wherein when the inkjet head module is removed from the path after the ink discharging process, the ink in the path moves to the tank. 3. The inkjet printing method according to claim 1, wherein the liquid level of the ink in the tank at the end of the ink discharging process is at a position lower than the connecting portion between the inkjet head module and the path. Device. The inkjet head module is connected to the two tanks by the two paths connected to each of the two tanks, and a buffer tank is connected to the two tanks,
one of the two tanks stores ink to be supplied to the inkjet head module;
the other of the two tanks stores the ink returned from the inkjet head module;
4. The inkjet printing apparatus according to any one of claims 1 to 3, wherein in the ink discharging process, the ink discharged from the two tanks is moved to the buffer tank. an inkjet head module including an inkjet head;
a tank for storing ink;
a path connecting the inkjet head module and the tank;
When the inkjet head module is removed, prior to the removal of the inkjet head module, the liquid level of the ink in the tank is set to a specified height at which the tank can receive the ink corresponding to the capacity of the path. a control unit that executes an ink discharge process for discharging ink from the tank;
When the inkjet head module is removed from the path after the ink discharging process, the ink in the path moves to the tank,
The inkjet head module is connected to the two tanks by the two paths connected to each of the two tanks, and a buffer tank is connected to the two tanks,
one of the two tanks stores ink to be supplied to the inkjet head module;
the other of the two tanks stores the ink returned from the inkjet head module;
The inkjet printing apparatus, wherein in the ink discharging process, the ink discharged from the two tanks is moved to the buffer tank.