JP6950682B2 - How to maintain the droplet ejection device and the droplet ejection device - Google Patents

Description

The present invention relates to a droplet ejection device and a maintenance method for the droplet ejection device.

There is a droplet ejection device (inkjet recording device) that ejects droplets of ink or the like from a nozzle to record an image or form a film or a structure. In this droplet ejection device, since it is necessary to eject droplets normally from the nozzle, conventionally, various methods have been used to inspect whether or not the droplets (ink) are ejected normally, or there is an abnormality. Maintenance technology has been developed to eliminate the abnormality in some cases.

As a method for resolving such an abnormality, there is known a technique of flushing out clogging or the like by flowing ink into the ink flow path of an inkjet recording device at a pressure stronger than usual. In particular, when an abnormality occurs in some of the recording heads (discharging heads), the ink (liquid to be ejected) is selectively flowed to the part of the recording heads, so that the ink is clogged more efficiently. (For example, Patent Document 1).

Japanese Unexamined Patent Publication No. 2012-000883

However, when the liquid that is selectively pressurized is sent to some of the discharge heads, the other is used by using a solenoid valve or the like so that the liquid is not sent to the other discharge heads. The flow path to the discharge head is temporarily blocked. However, in this solenoid valve, a movable part (movable iron piece) that closes or opens the flow path usually moves rapidly according to the switching of opening and closing, so that the opening and closing operation itself causes a pressure wave in the liquid or is movable. There is a problem that the liquid in the discharge head is suddenly moved by the impact corresponding to the movement of the parts being transmitted to the discharge head, and the meniscus surface at the tip of the liquid in the discharge head is destroyed.

An object of the present invention is a droplet ejection device and a liquid that can easily and easily perform pressure maintenance on a part of the ejection heads while appropriately maintaining the meniscus surface of the liquid to be ejected. The purpose is to provide a maintenance method for a dropping device.

In order to achieve the above object, the invention according to claim 1 is
A plurality of ejection heads having nozzles for ejecting droplets,
A liquid flow path for introducing the liquid to be discharged into each of the plurality of discharge heads,
An individual opening / closing unit that switches between a communication state and a non-communication state between the liquid flow path and the plurality of discharge heads in groups of at least two or more.
A liquid feeding means for pressurizing and feeding a liquid into the discharge head via the liquid flow path,
With some of the individual opening / closing parts open, a liquid is pressurized and sent into some of the discharging heads corresponding to the part of the individual opening / closing parts to perform a discharge operation, and then all the individual opening / closing parts are performed. and pressure control means for Ru liquids to perform the spitting discarded operation by pressurized pumping fluid in all of said discharge head with opened closing portion,
It is a droplet ejection device characterized by the present invention.

The invention according to claim 2 is the droplet ejection device according to claim 1.
The liquid flow path includes an intermediate flow path through which the liquid flows through the intermediate storage section and a bypass flow path provided in parallel with the intermediate flow path and through which the liquid flows without passing through the intermediate storage section.
The intermediate flow path is provided with an intermediate storage section opening / closing section for switching whether or not liquid can flow in or out of the intermediate storage section.
The detour flow path is provided with a detour flow path opening / closing portion for opening / closing the detour flow path.
When the liquid is pressurized and sent while the part of the individual opening / closing part is opened, the pressurizing control means closes the intermediate storage part opening / closing part and opens the detour flow path opening / closing part. It is characterized by.

The invention according to claim 3 is the droplet ejection device according to claim 2.
A decompression means for reducing the pressure of the liquid in the liquid flow path is provided.
The pressurizing control means pressurizes the liquid to the part of the discharge heads, and then pressurizes the liquid in the liquid flow path by the depressurizing means before opening all the individual opening / closing portions. It is characterized by reducing the pressure and opening the opening / closing part of the intermediate storage part.

Further, the invention according to claim 4 is the droplet ejection device according to claim 3.
The depressurizing means is characterized by including a suction means for sucking the liquid in the liquid flow path.

The invention according to claim 5 is the droplet ejection device according to claim 4.
After opening the opening / closing part of the intermediate storage part, the pressurization control means sucks the liquid in the liquid flow path and the intermediate storage part so that the pressure of the liquid in the intermediate storage part becomes a predetermined set value. It is characterized by being sucked by means.

The invention according to claim 6 is the droplet ejection device according to claim 4 or 5.
A storage unit for storing the liquid to be pressurized and sent to the discharge head by the liquid feeding means, and a storage unit.
A recovery flow path that returns the liquid sucked by the suction means to the storage unit,
It is characterized by having.

The invention according to claim 7 is the droplet ejection device according to any one of claims 1 to 6.
It is characterized by comprising a pressurized supply control means for dividing and performing the pressurized feeding of the liquid for each of the discharging heads having a predetermined maximum supply number or less.

Further, the invention according to claim 8 is
Between a plurality of discharge heads having nozzles for discharging droplets, a liquid flow path for introducing a liquid to be discharged into each of the plurality of discharge heads, and the liquid flow path and the plurality of discharge heads. A droplet discharge portion including an individual opening / closing unit for switching between a communication state and a non-communication state for each group of at least two or more, and a liquid feeding means for pressurizing and feeding a liquid into the discharge head via the liquid flow path. It ’s a device maintenance method.
With some of the individual opening / closing parts open, a liquid is pressurized and sent into some of the discharging heads corresponding to the part of the individual opening / closing parts to perform a discharge operation, and then all the individual opening / closing parts are performed. it is a maintenance method of a droplet ejection apparatus which comprises a pressure control step of Ru liquid in the all of the discharge head in the open state of the switching unit to perform the spitting discarded operation by pressurized pumping fluid.

According to the present invention, in the droplet ejection device, it is possible to easily and easily perform pressure maintenance on a part of the ejection heads while appropriately maintaining the meniscus surface of the liquid to be ejected. There is.

It is an overall perspective view of the inkjet recording apparatus of embodiment of this invention. It is a figure explaining the structure which concerns on the ink flow path in an inkjet recording apparatus. It is a figure which shows the example of the cross-sectional structure of the individual supply valve. It is a block diagram which shows the functional structure of an inkjet recording apparatus. It is a flowchart which shows the control procedure of the pressure maintenance process executed by the inkjet recording apparatus of this embodiment.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is an overall perspective view of an inkjet recording device 100, which is one of the embodiments of the droplet ejection device of the present invention.

The inkjet recording device 100 is a one-pass type device having a plurality of line heads, and includes a transport unit 10, an image forming unit 20, an ink storage unit 30, and the like.

The transport unit 10 includes a drive roller 11, a transport motor 12, a transport belt 14, and the like. The transfer motor 12 rotates the drive roller 11 at a predetermined speed. An endless transport belt 14 is wound around the drive roller 11 together with a driven roller (not shown), and the transport belt 14 orbits around the drive roller 11 due to the rotation of the drive roller 11. The recording medium is placed on the transport surface with the outer surface of the transport belt 14 as the transport surface, and the recording medium is transported in the transport direction as the transport belt 14 orbits.

The image forming unit 20 includes a carriage 22, a carriage elevating unit 23, a reading unit 24, and the like, and the combination of these carriages 22 and the carriage elevating unit 23 is the number of sets according to the number of ink colors (here, 8 sets). ) It is provided. Each of the carriages 22 extends in a direction intersecting the transport direction (x direction) of the recording medium by the transport unit 10, here, in the width direction (y direction) orthogonal to each other, and is a surface of the transport surface of the recording medium by the transport unit 10. A plurality of inkjet heads 211 (see FIG. 2, ejection heads) are fixed so as to be arranged upward (z direction) and eject ink droplets (liquid to be ejected) over the entire width of the conveyed recording medium. It has a line head structure. The plurality of carriages 22 are provided at different positions in the transport direction. The carriage 22 is provided so that the distance from the transport surface upward can be changed by the carriage elevating portion 23, and the distance from the transport surface of the inkjet head 211 is also changed as the carriage 22 moves.

The carriage elevating unit 23 changes the distance of the carriage 22 from the transport surface. The carriage elevating portion 23 includes an elevating motor 232, an electromagnetic brake 233, a beam member 234, a support portion 235, and the like.
Two beam members 234 are provided substantially parallel to each other in the direction intersecting the transport direction (here, the orthogonal direction, that is, the width direction) at the upper portion of the transport belt 14 (the transport surface side of the recording medium), and the beam member 234 is provided. Support portions 235 are fixed to both ends. An elevating motor 232, an electromagnetic brake 233, and a carriage 22 are attached to the support portion 235.
The carriage 22 is moved up and down according to the operation of the elevating motor 232 and the electromagnetic brake 233 driven based on the control signal from the control unit 40 (see FIG. 4) to determine the position.

The elevating motor 232 moves the carriage 22 at a predetermined elevating speed. As the elevating motor 232, for example, a servo motor or a stepping motor is used.

The electromagnetic brake 233 maintains the fixed state of the carriage 22, and by releasing this fixed state in response to a drive signal, the carriage 22 can be temporarily moved by the elevating motor 232. That is, in a normal state including when the power is turned off, the electromagnetic brake 233 fixes the carriage 22. As the electromagnetic brake 233, for example, a disc brake is used.

The reading unit 24 reads the image recorded on the recording medium. The reading unit 24 includes a line sensor having an image pickup element arranged so that the surface of the recording medium can be imaged over the recordable width of the recording medium. As the line sensor, a well-known one such as a CCD sensor or a CMOS sensor is used. By sequentially imaging in the width direction with the line sensor while transporting the recording medium in the transport direction, it is possible to perform two-dimensional imaging on the recording medium, and the imaging data is sequentially sent to the control unit 40. It is used for inspection of recorded images.

The ink storage unit 30 stores inks of each color used for image recording and supplies them to the inkjet head 211. Here, each configuration of the ink storage unit 30 is arranged in a dedicated rack 35 or the like, and is connected to the image forming unit 20 via a pipe such as a tube.

Next, the configuration related to the ink flow path (liquid flow path) from the ink storage unit 30 to the image forming unit 20 in the inkjet recording apparatus 100 of the present embodiment will be described.
FIG. 2 is a diagram illustrating a configuration related to an ink flow path in the inkjet recording apparatus 100 of the present embodiment.

The ink storage unit 30 includes a main tank 31, a supply pump 32, and the like.
The main tanks 31 are provided for each ink color and are arranged in the rack 35. The ink in the main tank 31 is sent to the image forming unit 20 by the supply pump 32. The main tank 31 is entirely replaceable, and is formed to be detachably attached to and detachable from the ink flow path to the supply pump 32 regardless of the operating state of the supply pump 32. That is, when the main tank 31 is attached while the supply pump 32 is in the operating state, the ink feeding to the image forming unit 20 is immediately restarted.
The supply pump 32 is not particularly limited, but for example, a diaphragm pump, a tube pump, or the like can be used.

In the image forming unit 20, the ink sent from the main tank 31 by the supply pump 32 is stored in the sub tank 251 (storage unit). The sub tank 251 is provided with an ink flow path (circulation flow path) that returns the ink sent from the sub tank 251 to the sub tank 251 after reaching the inkjet head 211.

From the sub tank 251 to the inkjet head 211 (liquid feeding flow path), a flow meter 252, a liquid feeding pump 253 (liquid feeding means), a filter 254, a degassing module 255, and a liquid feeding common flow path 256 (common). A flow path) is provided. A plurality of individual flow paths 257 are branched from the liquid feed common flow path 256, and ink is sent to the inkjet head 211 through the individual supply valve 258 (individual opening / closing portion) and the damper 259, respectively. Two inkjet heads 211 are connected to each damper 259.

Between the degassing module 255 and the liquid feed common flow path 256, the ink flow path is branched into an intermediate tank flow path 260 (intermediate flow path) and a maintenance flow path 265 (detour flow path). The intermediate tank flow path 260 is provided with an intermediate tank flow valve 261, an intermediate tank 262 (intermediate storage portion), a common supply valve 263, and the like.
The intermediate tank flow valve 261 and the common supply valve 263 constitute an intermediate storage section opening / closing section.
The maintenance flow path 265 is provided with a maintenance flow path flow valve 266 (a detour flow path opening / closing portion).

In the collection flow path 27 from the collection port (outlet) of the inkjet head 211 to the sub tank 251 first, the check valves 271 are connected after the flow paths of the ink discharged from the two inkjet heads 211 branched by the damper 259 merge. It joins the recovery common flow path 272. Then, the ink is returned from the recovery common flow path 272 to the sub tank 251 via the recovery valve 273 and the circulation valve 274. Further, a recovery pump 275 is provided in parallel with the circulation valve 274.

Further, the end portion of the liquid feeding common flow path 256 opposite to the ink inflow side end portion is directly connected to the downstream side of the recovery valve 273 via the bypass valve 270.
Further, between the liquid feed pump 253 and the filter 254, a check valve is located on the downstream side of the maintenance flow path flow valve 266 of the maintenance flow path 265 and on the downstream side of the intermediate tank flow valve 261 of the intermediate tank flow path 260, respectively. A release flow path for returning ink to the sub tank 251 via 281, 282, and 283 is provided. When the ink sent from the sub tank 251 by the liquid feeding pump 253 does not flow to the inkjet head 211 or cannot flow due to a defect in the filter 254, the degassing module 255, the intermediate tank 262, the liquid feeding common flow path 256, etc. When the ink staying in the middle of the flow path increases and the ink pressure rises, when the pressure of this ink exceeds a predetermined pressure threshold, the check valves 281 to 283 as these relief valves are opened and the ink Can be returned to the sub tank 251.

The capacity of the sub tank 251 is not particularly limited, but here, it is smaller than the capacity of the main tank 31. The sub tank 251 is provided with a reference sensor 251a, a lower limit sensor 251b, an upper limit sensor 251c, and the like in order to detect the amount of ink stored. The reference sensor 251a detects whether or not a standard amount of ink for determining whether or not ink is supplied by the supply pump 32 from the main tank 31 to the sub tank 251 is stored. That is, when the ink storage amount is smaller than the standard storage amount, the supply pump 32 is operated, and when the ink storage amount is larger than the standard storage amount, the supply pump 32 is stopped.

The lower limit sensor 251b detects whether or not the lower limit storage amount of ink for determining whether or not the operation of the inkjet head 211 can be prohibited is stored. That is, when the lower limit storage amount is smaller than the standard storage amount and the ink storage amount is smaller than the lower limit storage amount, the operation (ink ejection) of the inkjet head 211 is prohibited. If the ink is properly supplied from the main tank 31 to the sub tank 251 the ink amount in the sub tank 251 does not decrease significantly from the standard storage amount. Means the occurrence of.

The upper limit sensor 251c detects whether or not the upper limit storage amount of ink indicating the danger of overflowing the sub tank 251 is stored. The upper limit storage amount is set to be larger than the sum of the standard storage amount and the ink capacities of the entire circulation flow path (liquid feeding flow path, inkjet head 211 and recovery flow path 27), that is, the ink is the nozzle of the inkjet head 211. Even if all the ink is returned to the sub tank 251 without being ejected from the above, the upper limit storage amount will not be exceeded. means.
In the inkjet recording apparatus 100 of the present embodiment, the sub tank 251 is open to the atmosphere, and the pressure applied to the ink is normally maintained at substantially atmospheric pressure.

The flow meter 252 detects and outputs the amount of liquid sent from the sub tank 251 to the inkjet head 211 side by the liquid feeding pump 253. Here, the measured value of the flow meter 252 is used for status display and holding of history information by the operation display unit 42 (see FIG. 4), and is not used for abnormality detection or the like, but is sent. It may be used for detecting a liquid abnormality or the like.

The liquid feed pump 253 delivers the ink inside the sub tank 251 to the filter 254 and its downstream side, that is, to the side of the inkjet head 211 (liquid feed flow path) at a predetermined liquid feed rate (liquid feed amount per hour). Here, one liquid feed pump 253 is provided for the sub tank 251 to supply ink to all the inkjet heads 211, but each of a predetermined number of inkjet heads 211 is divided into a plurality of blocks and each feeds separately. Ink may be supplied from the sub tank 251 by the liquid pump 253. The liquid feeding capacity of the liquid feeding pump 253 is sufficient as long as it can sufficiently supply the maximum ink ejection amount per hour by the inkjet head 211 accompanying the image forming operation, and the ink dispensing speed corresponding to this maximum ink ejection amount. Is smaller than the maximum liquid feeding rate of the supply pump 32. Therefore, the liquid feed pump 253 may have a liquid feed capacity smaller than that of the supply pump 32, but may be the same as the supply pump 32, that is, the same type. In this case, it is not necessary to operate the liquid feeding pump 253 at the maximum ink feeding speed even in a situation where the ink is ejected most by the inkjet head 211 (such as during formation of a solid image).
In addition, the liquid feed pump 253 can pressurize and feed ink that exceeds the ink ejection capacity to the inkjet head 211. That is, the ink inside the common flow path 256, the individual flow path 257, and the inkjet head 211 to which this ink is fed is temporarily set to a state higher than the atmospheric pressure.

The filter 254 removes foreign substances such as dust and dirt, impurities, and large bubbles in the ink. As described above, the sub tank 251 is open to the atmosphere, and these foreign substances, impurities and air bubbles may be mixed in. Therefore, the filter 254 prevents them from being sent to the inkjet head 211.

The degassing module 255 removes air (gas) contained in the ink. As the degassing module 255, for example, a structure is used in which the air in the ink is selectively sucked toward the vacuum region side by bringing the ink and the vacuum region into contact with each other through the degassing film. The degassing film can have, for example, a large number of hollow fine thread structures having a vacuum inside in order to efficiently increase the contact area with the ink and bring it into contact with the ink more evenly.
Here, the air on the vacuum region side of the degassing module 255 is sucked by the vacuum pump 293. The vacuum region referred to here does not necessarily have to be an ultra-high vacuum, and a predetermined pressure sufficiently lower than the atmospheric pressure is set in advance. The pressure sensor 294 measures the air pressure on the vacuum region side, and the operation of the vacuum pump 293 is controlled according to the measured value of the pressure sensor 294.

The vacuum region side of the degassing module 255 is connected to the chamber 292 via a check valve 291. Ink that slightly permeates the degassing film or leaks to the vacuum region side at once when the degassing film is torn flows into the bottom of the chamber 292 and is stored. The ink accumulated at the bottom of the chamber 292 is detected by the liquid amount sensor 292a to determine whether or not an abnormal amount has leaked. At the time of abnormality detection, the operation of the vacuum pump 293 and each part is stopped, or the vacuum region is in the atmosphere. It is communicated. In this way, the chamber 292 is used as a trap for the leaked ink, and by preventing the leaked ink from reaching the vacuum pump 293, failure or damage to the vacuum pump 293 is prevented.

The liquid amount sensor 292a includes an actuator that directly measures the amount of liquid, a member that measures the weight change of the chamber 292, and a member that changes according to the weight change, for example, an actuator that deforms by a load according to the weight of the chamber 292. A signal that can be measured optically, electrically, or magnetically according to the deformation can be used.

The suction unit 29 including the chamber 292, the liquid amount sensor 292a, the pressure sensor 294, and the vacuum pump 293 is commonly provided for the degassing module 255 in the circulation flow path provided for each color of ink. , The structure is such that the check valve 291 merges downstream (on the side of the chamber 292). That is, when ink of a certain color leaks from the degassing module 255, the check valve 291 causes the ink of the certain color to flow into the vacuum region side of the degassing module 255 of the circulation flow path related to the ink of another color. Is prevented.

The individual supply valve 258 can supply ink from the liquid feed common flow path 256 to the individual flow paths 257 communicating with a predetermined number (two in this case) of the inkjet heads 211 from the liquid feed common flow path 256, that is, each The communication state and the non-communication state of the individual flow path 257 and the inkjet head 211 are switched. While all of these individual supply valves 258 are opened during normal image recording operation, these are individual when the ink in the intermediate tank 262 and the liquid feed common flow path 256 is returned to the sub tank 251 without being discharged to the outside and collected. The supply valve 258 is closed and the bypass valve 270 is opened. Further, when ink is selectively supplied to some of the inkjet heads 211 for inspection, cleaning, maintenance, etc. of some of the inkjet heads 211, individual flow paths 257 communicating with some of the inkjet heads 211 are used. Only the individual supply valve 258 provided in the above is opened, and the other individual supply valves 258 are closed.
Here, four individual flow paths 257 are described as an example, but this number can be appropriately set within a range that does not cause a problem in the supply of ink to the inkjet head 211 and the ejection operation from the nozzle.

FIG. 3 is a diagram showing an example of a cross-sectional structure of the individual supply valve 258 of the present embodiment.
For the individual supply valve 258 and other valves that switch the presence or absence of ink flow, here, an electromagnetic valve, for example, a plunger (movable iron piece) 2581 provided in the ink flow path is moved by electromagnetic force or spring force. A solenoid valve that switches the opening and closing of the flow path is used. The plunger 2581 is arranged along the direction of the ink flow path, and when a predetermined voltage is applied to the solenoid 2582 under the control of the control unit 40 (see FIG. 4), the plunger 2581 resists the repulsive force of the spring 2583. Then, it moves to the downstream side (the side of the inkjet head 211) so as to block the ink flow path, and when the voltage is released, it returns to the original upstream side position according to the repulsive force of the spring 2583 and the ink flow path. Is released. In FIG. 2, the white valves such as the individual supply valve 258 are valves that are open in the normal state (when the ground voltage is supplied or when the voltage is not supplied), and are painted black such as the intermediate tank flow valve 261. The valve is a valve that is normally closed.
The moving speed of the plunger 2581 is sufficiently fast, and the open state and the closed state can be quickly switched. However, a pressure wave is generated in the ink in response to this movement, or the outer frame of the moved plunger 2581 and the individual supply valve 258. A mechanical impact may occur due to a collision with the vehicle.

The damper 259 is a buffer portion that reduces pressure fluctuations that occur depending on the ink ejection status from the plurality of inkjet heads 211 and the liquid feed status from the liquid feed pump 253. The damper 259 is provided with a flexible film or the like, and bends in response to pressure fluctuations related to the operation of the other inkjet head 211 or the liquid feed pump 253 to suppress its ripple effect, so that when ink is ejected from the inkjet head 211, the damper 259 is provided with a flexible film or the like. By applying pressure to the ink in the inkjet head 211 with an appropriate pressure pattern, the ink is ejected normally. Here, the frequency of the pressure fluctuation mainly reduced by the damper 259 is smaller than the frequency of the pressure wave of the ink accompanying the movement of the plunger 2581 described above.

A plurality of nozzles are arranged on the inkjet head 211. The ink supplied from the damper 259 to the inkjet head 211 is further branched into an ink flow path communicating with each nozzle. A pressure chamber (not shown) is provided in this ink flow path, and ink is ejected by applying pressure to the ink in the pressure chamber with an appropriate waveform, or ink that is not ejected is appropriately vibrated in the nozzle. This prevents the ink from drying out and deteriorating. The method of pressurizing the ink in the pressure chamber can be selected from various well-known methods, but here, the pressure chamber is deformed by applying a voltage using a piezoelectric element or a diaphragm to change the pressure on the ink. It has a piezo-type configuration. The liquid level (meniscus surface) of the ink is appropriately maintained in the vicinity of the opening of each nozzle. As a result, when pressure is applied, droplets of an appropriate shape and size are separated from the ink in the nozzle and ejected.

The check valve 271 enables the ink discharged from the inkjet head 211 without being ejected by the nozzle to flow into the common recovery common flow path 272, while the ink from the recovery common flow path 272 to the inkjet head 211. Prevents backflow. That is, the ink discharged from a part of the inkjet heads 211 does not flow back to the other inkjet heads 211.

The intermediate tank flow valve 261 is provided near the inlet of the intermediate tank flow path 260 separated from the maintenance flow path 265 downstream of the degassing module 255, and is opened and closed according to whether or not ink can flow into the intermediate tank flow path 260. NS. The intermediate tank flow path 260 is opened when ink is supplied to the inkjet head 211 during normal image formation.

The intermediate tank 262 is a tank having a smaller capacity than the sub tank 251 and is used to keep the ink in the inkjet head 211 at an appropriate back pressure (predetermined set value), that is, a pressure lower than the atmospheric pressure (negative pressure). For this purpose, the intermediate tank 262 is formed of a flexible material, can be appropriately deformed by the pressure difference between the ink pressure and the outside air pressure, and has a nozzle surface on which the nozzle openings of the inkjet head 211 are arranged. It is provided at a position slightly lower in the vertical direction than the above. As a result, the ink does not naturally leak from the nozzle opening except when the ink can be intentionally ejected by further applying pressure to the ink in the pressure chamber in the liquid feed pump 253 or the inkjet head 211. .. On the other hand, when the ink is ejected from the nozzle opening and the ink in the inkjet head 211 is reduced, the ink flows from the intermediate tank 262 to the inkjet head 211 according to the reduced amount (ink ejection amount).

Further, the intermediate tank 262 is provided with an intermediate upper limit sensor 262a and an intermediate reference sensor 262b.
The intermediate reference sensor 262b detects an intermediate reference ink amount (ie, indirectly the appropriate back pressure itself) that is appropriately set to obtain an appropriate back pressure. Whether or not the liquid feed pump 253 operates is appropriately controlled according to whether or not the intermediate reference ink amount of ink is detected by the intermediate reference sensor 262b. Further, the intermediate upper limit sensor 262a detects an upper limit ink amount determined so as not to be dangerous for maintaining the intermediate tank 262. Normally, when the amount of ink in the intermediate tank 262 rises more than usual and the pressure of the ink rises, the check valve 283 is opened and the ink is returned to the sub tank 251. However, when the check valve 283 does not function normally. For example, in response to the detection by the intermediate upper limit sensor 262a, all the processes related to the ink supply operation can be stopped or other appropriate processes can be performed.

The maintenance flow path flow valve 266 switches whether or not the ink delivered by the liquid feed pump 253 can flow into the maintenance flow path 265. As shown here, the maintenance flow path flow valve 266 and the intermediate tank flow valve 261 can be closed at the same time. For example, even during the image recording operation, if the amount of ink inside the intermediate tank 262 is within an appropriate range and the ink is not additionally supplied to the intermediate tank 262 by the liquid feed pump 253, the maintenance flow path is distributed. Both the valve 266 and the intermediate tank flow valve 261 are closed.

The maintenance flow path 265 was pressurized and sent out to the liquid feed common flow path 256 and the inkjet head 211 by the liquid feed pump 253 for the purpose of introducing ink, discharging air (air bubbles), and flushing out factors of clogging. It is used when sending ink as it is. For example, by closing all the individual supply valves 258 and sending the pressurized ink while opening the bypass valve 270, the ink is introduced into the liquid feeding common flow path 256, and the ink is made to flow inside. The air is discharged to the recovery flow path 27 and the sub tank 251. Further, by sending the pressurized ink by the liquid feed pump 253 with both the individual supply valve 258 and the recovery valve 273 open, the ink flow path in each inkjet head 211 is filled with ink. Further, the ink pressurized from each nozzle of the inkjet head 211 is sent by the liquid feed pump 253 with the partial or all individual supply valves 258 opened and the recovery valve 273 closed. Is discharged to discharge air bubbles in the nozzle, and the cause of clogging of the nozzle opening or the like, for example, a solidified or thickened ink block, is discharged to eliminate the clogging. At this time, by reducing the number of the individual supply valves 258 to be opened, the pressure of the ink supplied to the inkjet head 211 related to the relatively open individual supply valves 258 can be increased.

The common supply valve 263 is particularly pressurized via the maintenance flow path 265 by switching whether or not ink can be supplied from the intermediate tank 262 to the liquid feed common flow path 256 and each inkjet head 211 and by being closed. When the ink is supplied to the common flow path, the ink is prevented from flowing back to the intermediate tank 262.

The recovery common flow path 272 that merges the ink discharged without being ejected from the inkjet head 211 and flows to the side of the sub tank 251 has substantially the same configuration as the liquid feed common flow path 256, and is formed in a tube shape, for example. ing. Both the liquid feed common flow path 256 and the recovery common flow path 272 are formed to be sufficiently thicker (larger cross-sectional area) than the individual flow paths 257, so that the flow rate is related to the change in the amount of ink supplied to the individual flow paths 257. And suppress the spread of the influence of changes in ink pressure.

The recovery valve 273 switches whether or not ink is returned from the recovery common flow path 272 to the sub tank 251. Further, the recovery valve 273 is closed when the bypass valve 270 is open so that the ink flowing from the liquid feeding common flow path 256 through the bypass valve 270 does not return to the recovery common flow path 272. To.

The ink that has passed through the bypass valve 270 or the recovery valve 273 is returned to the sub tank 251 through the circulation valve 274 or the recovery pump 275 (ink suction means). When the ink that has been once sent from the liquid feed pump 253 and has not been discharged from the nozzle of the inkjet head 211 is taken out and returned to the sub tank 251, the circulation valve 274 is closed and the recovery pump 275 is operated. As a result, the ink remaining in each part of the inkjet head 211 and the intermediate tank 262 is sucked and returned to the sub tank 251 so that the ink can be removed from the inside of the inkjet head 211 and the intermediate tank 262. ..
The bypass valve 270 and the recovery pump 275 constitute a decompression means.

Further, the recovery pump 275 sucks not only the ink but also the air in the ink flow path. When ink is not supplied to the circulation flow path in the initial state or at the time of restarting after maintenance, the recovery pump 275 once sucks the air in the circulation flow path, and in particular, almost the air in the intermediate tank 262 is sucked. By completely removing the ink and then introducing the ink into the intermediate tank 262 by the liquid feed pump 253, air remains in the intermediate tank 262 to generate unnecessary pressure, or the air is mixed with the ink. It is possible to avoid causing ejection defects or the like due to the outflow and being sent to the inkjet head 211. Normally, when introducing ink, the removal of air by the recovery pump 275, the recovery of ink, and the introduction of ink by the liquid feed pump 253 are repeated a plurality of times in the circulation flow path, particularly from the sub tank 251 to the inkjet head 211. It is possible to introduce the ink while more surely preventing the air from remaining between the two.

When it is not necessary to remove the ink inside the inkjet head 211 or the intermediate tank 262 and simply circulate the ink delivered by the liquid feed pump 253, the circulation valve 274 is opened without operating the recovery pump 275. As a result, a circulating flow of ink is generated only by the liquid feeding pressure of the liquid feeding pump 253.

The downstream side of the filter 254, the downstream side of the intermediate tank 262, and the liquid feeding common flow path 256 are provided with discharge valves that can be opened by the user to discharge ink as needed.

Next, the functional configuration of the inkjet recording apparatus 100 of the present embodiment will be described.
FIG. 4 is a block diagram showing a functional configuration of the inkjet recording device 100.
The inkjet recording device 100 includes the above-mentioned supply pump 32, liquid feed pump 253, recovery pump 275, vacuum pump 293, reference sensor 251a, lower limit sensor 251b, upper limit sensor 251c, intermediate upper limit sensor 262a, intermediate reference sensor 262b, and pressure sensor 294. , Liquid level sensor 292a, intermediate tank flow valve 261, maintenance flow path flow valve 266, common supply valve 263, individual supply valve 258, bypass valve 270, recovery valve 273, circulation valve 274, transfer motor 12, electromagnetic brake 233, ascending / descending In addition to the motor 232 and the reading unit 24, the control unit 40 (pressurization supply control means, pressurization control means), the communication unit 41, the operation display unit 42, the conveyor motor 12, the head drive unit 221 and so on. It includes a motor driver 231, a notification operation unit 43, a bus 49, and the like.

The control unit 40 controls the overall operation of the inkjet recording device 100 and controls the operation of each unit. The control unit 40 includes a CPU 401 (Central Processing Unit), a RAM 402 (Random Access Memory), a ROM 403 (Read Only Memory), a memory 404, and the like.

The CPU 401 performs various arithmetic processes to control the transfer of the recording medium, the supply of ink, the ejection of ink, the maintenance operation, and the like in the inkjet recording apparatus 100. Further, the CPU 401 performs various processes related to image formation based on the image data, the status signal of each part, the clock signal, and the like according to the program read from the ROM 403.

The RAM 402 provides the CPU 401 with a working memory space and stores temporary data.
The ROM 403 stores a control program, initial setting data, and the like. The control program includes a program related to ink supply control and maintenance operation of the inkjet recording apparatus 100.

Further, the ROM 403 includes a non-volatile memory that can be overwritten and updated, and stores an individual maintenance execution flag 403a indicating whether or not the individual maintenance described later is executed. The memory 404 includes a RAM for temporarily storing image data to be formed.

The head drive unit 221 generates and outputs a drive voltage signal that deforms the pressure chamber (piezoelectric element) in order to properly eject ink from the nozzles in each inkjet head 211. The head drive unit 221 selects a voltage waveform pattern stored in advance based on the control signal from the control unit 40 to generate a power-amplified drive voltage signal, and each of the head drive units 221 responds to the image data input from the memory 404. Whether or not the drive voltage signal can be output to the piezoelectric element is switched.
The wiring related to the head drive unit 221 is formed together with the ink flow path in the inkjet head 211, and is partially formed separately.

The motor driver 231 outputs a drive signal to the electromagnetic brake 233 and the elevating motor 232 in response to the control signal from the control unit 40, loosens the electromagnetic brake 233 and operates the elevating motor 232 to move the carriage to a desired position. Alternatively, the lifting motor 232 is stopped and the carriage is fixed by the electromagnetic brake 233.

The communication unit 41 is a communication interface that controls a communication operation with an external device. The communication interface includes one or a plurality of communication interfaces corresponding to various communication protocols, such as a LAN board and a LAN card. The communication unit 41 acquires image data to be formed and setting data (job data) related to image recording from an external device based on the control of the control unit 40, and also transmits status information and the like to the external device. Can be done.

The operation display unit 42 displays the status of the inkjet recording device 100, the operation menu, and the like in response to the control signal from the control unit 40, and receives the user's operation and outputs the operation to the control unit 40. The operation display unit 42 includes, for example, a liquid crystal display unit in which a touch sensor as an operation receiving means is provided so as to overlap with a display screen as a display means. The control unit 40 displays the status, various menus for receiving commands by the touch sensor, and the like on the liquid crystal display unit, and provides information on the contents and position of the displayed menu and the user's touch operation detected by the touch sensor. A control operation is performed in which each part of the inkjet recording apparatus 100 performs the corresponding processing.

The notification operation unit 43 performs a predetermined notification operation in response to the control signal of the control unit 40. Examples of the configuration for performing the notification operation include an LED lamp that emits light of a predetermined color and / or a beep sound generating unit that generates a beep sound.
In addition to these, the inkjet recording device 100 may include a mounting abnormality detection sensor or the like that detects that the supplied recording medium is not normally mounted on the transport surface.

The bus 49 is a path for electrically connecting each of the above configurations to exchange signals.

Next, the maintenance operation of the inkjet head 211 in the inkjet recording apparatus 100 of the present embodiment will be described.
In the inkjet recording apparatus 100 of the present embodiment, when the nozzle of a specific inkjet head 211 is clogged, or when air bubbles or the like are mixed in and ink cannot be ejected normally, the inkjet head 211 can be discharged. By selectively pressurizing and sending ink, individual maintenance processing is performed to allow clogging and air bubbles to flow out from the nozzle opening.

At this time, since the pressurization of the ink by the liquid feed pump 253 (ink feed amount) is a fixed value, the pressure applied to each nozzle is the sum of the nozzle opening areas, that is, the number of selected nozzles. It will be inversely proportional. In individual maintenance, when the number of inkjet heads 211 to be maintained exceeds the predetermined maximum supply number so that ink is sent to each nozzle at a pressure equal to or higher than a predetermined pressure, the recording heads to be maintained are , Divided into a plurality of groups, and pressurized liquid feeding is performed for each group.

FIG. 5 is a flowchart showing a control procedure by the control unit 40 of the individual maintenance process executed by the inkjet recording apparatus 100 of the present embodiment.
This individual maintenance process is automatically performed when it is detected that a problem such as poor ink ejection has occurred in the nozzle of any of the inkjet heads 211 by inspection of the recorded image or the like, or by a predetermined input operation by the user. It will be started. The inkjet head 211 selected as the target for pressurized liquid feeding either allows the user to visually recognize the inspection image and perform a setting operation, or the control unit 40 automatically determines based on the inspection image. It is preferable that the inspection image is given a number, a symbol, or the like for each inspection image by each inkjet head 211 so that the user can easily select the inkjet head 211.

The control unit 40 (CPU401) closes the common supply valve 263 (step S101). Further, the control unit 40 closes the intermediate tank flow valve 261 and opens the maintenance flow path flow valve 266 (step S102). As a result, the intermediate tank 262 is separated from the ink flow path from the liquid feed pump 253 to the liquid feed common flow path 256.

The control unit 40 closes the individual supply valve 258 that communicates with the inkjet head 211 that is not subject to pressurized liquid feeding (step S103). At this time, the control unit 40 closes the bypass valve 270 and the recovery valve 273. Then, the control unit 40 operates the liquid feed pump 253 to pressurize and feed the ink to the inkjet head 211 of the pressurized liquid feed target (maintenance target) (step S104). At this time, since the bypass valve 270 and the recovery valve 273 are closed, the ink supplied to the inkjet head 211 can flow out only from the nozzle opening of each inkjet head 211, and the inside of the nozzle of the inkjet head 211 is clogged. And air bubbles are pushed out from the nozzle opening.

The control unit 40 opens the bypass valve 270 and the recovery valve 273 to release and reduce the pressure in the liquid feed common flow path 256 and the inkjet head 211 that have been raised by the operation of the liquid feed pump 253 (step S105). The control unit 40 determines whether or not the pressurization of all the inkjet heads 211 to be pressurized liquid has been completed (step S106). If it is determined that the pressurization is not completed (“NO” in step S106), the process of the control unit 40 returns to step S103.

When it is determined that the ink has been pressurized and fed into the ink flow paths of all the inkjet heads 211 to be pressurized liquid feed (“YES” in step S106), the control unit 40 sets the maintenance flow path flow valve 266. It is closed and the intermediate tank flow valve 261 and the common supply valve 263 are opened (step S107). As a result, the ink pressure in the intermediate tank 262 increases according to the amount of pressure increase in the ink in the liquid feeding common flow path 256.

The control unit 40 closes all the individual supply valves 258 (step S108). At this time, the bypass valve 270 and the recovery valve 273 are in the open state. The control unit 40 sucks the ink in the intermediate tank 262 by operating the recovery pump 275, and adjusts to reduce the pressure (ink amount) in the intermediate tank 262 to a set value (step S109).

The control unit 40 closes the bypass valve 270 and the recovery valve 273, and opens all the individual supply valves 258 (step S110). At this time, the meniscus shape of the liquid surface at each nozzle in the inkjet head 211 may be destroyed by the opening operation of the individual supply valve 258. The control unit 40 operates the liquid feed pump 253 to pressurize and supply ink to all the recording heads to discharge ink from each nozzle and reshape the meniscus shape of the liquid surface in each nozzle. (Step S111; pressurization control step).

The control unit 40 operates the transfer motor 12 and the head drive unit 221 to record a predetermined inspection image on the recording medium (step S112). Further, the control unit 40 operates the reading unit 24 to read the recorded inspection image, and detects an abnormality related to ink ejection from the inspection image. The control unit 40 determines whether or not there is a problem in the inspection image (step S113), and if there is a problem (if it is determined that it is not OK) (“NO” in step S113), the process is stepped. Return to S101 and restart the process from the beginning. If there is no problem (if it is determined to be OK) (“YES” in step S113), the control unit 40 ends the individual maintenance process.

Here, the processing after step S111 does not need to be executed immediately following the processing in step S110. For example, when the process of step S110 is executed, the control unit 40 sets the individual maintenance execution flag 403a, and then performs the processes after step S111 according to the individual maintenance execution flag 403a before the image recording is started. The individual maintenance execution flag 403a may be reset after the execution.

Further, the processes of steps S112 and S113 do not necessarily have to be executed in the individual maintenance process, but are performed as a part of a normal inspection process such as during a normal image recording operation or when the inkjet recording device 100 is started. It may be a thing.

As described above, the inkjet recording apparatus 100 of the present embodiment includes a plurality of inkjet heads 211 having nozzles for ejecting ink, individual flow paths 257 for introducing ink into each of the plurality of inkjet heads 211, and liquid feeding. The common flow path 256, the individual supply valve 258 that switches between the communication state and the non-communication state of the individual flow path 257 and the ink jet head 211 corresponding to the individual flow path 257, and the liquid feed common flow path 256 and the individual flow path. A liquid feed pump 253 that pressurizes and feeds ink into the inkjet head 211 via 257, and a part of the inkjet heads corresponding to the part of the individual supply valves 258 with a part of the individual supply valves 258 open. After the ink is pressurized and fed into the 211, all the individual supply valves 258 are opened to provide a control unit 40 as a pressurizing control means for pressurizing and feeding the ink into all the inkjet heads 211.
As a result, ink is pressurized and sent to some of the inkjet heads 211 by selectively opening and closing the individual supply valve 258 to remove clogging, thickened ink, dust, air bubbles, etc. in the inkjet heads 211, especially in the nozzles. While it is possible to perform pressure maintenance to effectively discharge ink, after reopening the closed individual supply valve 258, ink is again pressurized and sent to all inkjet heads 211 to perform a discharge operation. The ink meniscus surface in the nozzle, which may be destroyed when the individual supply valve 258 is reopened, can be repaired, and the ink can be reliably ejected at the time of subsequent image recording. Therefore, in the inkjet recording device 100, pressure maintenance can be selectively performed on a part of the recording heads while appropriately maintaining the meniscus surface of the ink easily and easily.

Further, between the liquid feed pump 253 and the liquid feed common flow path 256, an intermediate tank flow path 260 for flowing ink via the intermediate tank 262 and a maintenance flow path 265 for flowing ink without passing through the intermediate tank 262. The intermediate tank flow path 260 is provided with an intermediate tank flow valve 261 and a common supply valve 263 for switching whether or not ink flows in and out (liquid inflow and outflow) into the intermediate tank 262, and a maintenance flow path 265 is provided. Is provided with a maintenance flow path flow valve 266 that opens and closes the maintenance flow path 265, and the control unit 40 is an intermediate tank when the ink is pressurized and sent while a part of the individual supply valves 258 are open. The flow valve 261 and the common supply valve 263 are closed, and the maintenance flow path flow valve 266 is opened.
As a result, the pressure ink can be efficiently supplied to the inkjet head 211 without causing an extra pressure loss in the intermediate tank 262. Further, since a strong pressure is not applied to the intermediate tank 262, the intermediate tank 262 is not damaged.

Further, the control unit 40 is provided with a bypass valve 270 and a recovery pump 275 for reducing the pressure of the ink inside the liquid feeding common flow path 256 and the individual flow path 257, and the control unit 40 pressurizes and feeds the ink to a part of the inkjet heads 211. After liquefying, before opening all the individual supply valves 258, the bypass valve 270 is opened to release the pressure to the sub tank 251 communicating with the atmosphere to reduce the pressure of the ink in the liquid feeding common flow path 256. At the same time, the common supply valve 263 is opened.
As a result, it is possible to prevent the pressurized ink in the liquid feeding common flow path 256 from flowing back into the intermediate tank 262 and increasing the pressure in the intermediate tank 262 more than necessary.

Further, since the recovery pump 275 for sucking the ink in the liquid feed common flow path 256 is provided, the ink pressure in the liquid feed common flow path 256 cannot be completely lowered only by opening the bypass valve 270, or the ink pressure can be adjusted. When it takes an undesirably long time for the reduction, the ink pressure can be efficiently reduced by sucking the ink with the recovery pump 275.

Further, after opening the common supply valve 263, the control unit 40 sucks the ink of the liquid feed common flow path 256 and the intermediate tank 262 by the recovery pump 275 so that the ink pressure of the intermediate tank 262 becomes an appropriate value. ..
As a result, the pressure in the intermediate tank 262 (that is, the amount of ink) can be adjusted to an appropriate level for image recording, and after the individual maintenance process, the normal image recording operation can be promptly restored.

Further, since the sub tank 251 for storing the ink pressurized and supplied by the liquid feeding pump 253 and the recovery flow path 27 for returning the ink sucked by the recovery pump 275 to the sub tank 251 are provided, the ink is discharged from the nozzle of the inkjet head 211. The ink that has not leaked can be effectively reused, and therefore the wasteful consumption of ink can be reduced.

Further, since the control unit 40 divides the pressurization supply of the ink for each inkjet head 211 having a predetermined maximum supply number or less as the pressurization supply control means, the ink jet to which the ink is individually pressurized is supplied. When the number of heads 211 is large, the inkjet heads 211 are divided into appropriate numbers or less, and the pressure of the ink supplied under pressure to each inkjet head 211 is effectively maintained at a level required for individual maintenance. It can discharge clogged, thickened ink, dust and air bubbles.

Further, by using the above-mentioned maintenance method of the inkjet recording apparatus 100, it is possible to selectively perform pressure maintenance on a part of the recording heads while appropriately maintaining the meniscus surface of the ink easily and easily. ..

The present invention is not limited to the above embodiment, and various modifications can be made.
For example, in the above embodiment, an intermediate tank 262 is provided between the sub tank 251 and the inkjet head 211, and the intermediate tank 262 supplies ink to the inkjet head 211 related to normal image recording. An ink flow path that passes through the liquid feed pump 253 and an ink flow path that does not pass through the liquid feed pump 253 may be provided in parallel between the sub tank 251 and the inkjet head 211 so that ink can be directly supplied from the sub tank 251 to the inkjet head 211. ..

Further, in the above embodiment, the common individual supply valve 258 is provided for each of the two inkjet heads 211, but one individual supply valve 258 may be provided for each of the inkjet heads 211. ..

Further, in the above embodiment, all the processes related to the individual maintenance process are performed based on the control of the control unit 40, but some processes may be performed based on the input operation of the user.
For example, the selection of the inkjet head 211 to be individually maintained is performed based on the input operation of the user, and this selection operation is performed by the operation display unit 42 each time the process of step S106 is called. It may be displayed on the display screen of.
Further, for example, when the process of step S110 is executed and the individual maintenance execution flag 403a is set, the control unit 40 displays a display requesting an input operation of the process execution command of step S111 on the display screen of the operation display unit 42. The display may be maintained until the user executes the process of step S111 at a desired timing by a predetermined input operation.

Further, in the above embodiment, the ink that is not ejected or leaked is collected and returned to the sub tank 251. However, the ink that does not have such an ink circulation path and is once sent to the inkjet head 211 is All may be discharged or discharged.
In this case, the discharge valve may be provided so that the ink discharged from the intermediate tank 262 does not depend on the recovery pump 275 and flows out according to gravity.

Further, in the above embodiment, the solenoid valve has been described as an example, but the type of the individual supply valve 258 is not limited as long as a pressure wave or the like is generated in the ink according to the opening / closing operation of the movable portion.

Further, in the above embodiment, an inkjet recording device having a line head capable of ejecting a plurality of colors of ink has been described as an example, but the number of colors of the ink that can be ejected is arbitrary. Further, instead of the line head, a scanning type inkjet recording device may be used in which ink is ejected while scanning the inkjet head 211 with respect to the recording medium to record an image. Further, the device is not limited to the inkjet recording device, and may be various drop ejection devices for obtaining a film, a structure, or the like by ejecting droplets of a liquid other than ink from a nozzle.
In addition, specific details such as the configuration, arrangement, and control procedure shown in the above embodiment can be appropriately changed without departing from the spirit of the present invention.

The present invention can be used as a maintenance method for a droplet ejection device and a droplet ejection device.

10 Conveying unit 11 Drive roller 12 Conveying motor 14 Conveying belt 20 Image forming unit 211 Inkjet head 22 Carriage 221 Head driving unit 23 Carriage elevating part 231 Motor driver 232 Elevating motor 233 Electromagnetic brake 234 Valve member 235 Support part 24 Reading unit 251 Sub tank 251a Reference sensor 251b Lower limit sensor 251c Upper limit sensor 252 Flow meter 253 Liquid transfer pump 254 Filter 255 Degassing module 256 Liquid transfer common flow path 257 Individual flow path 258 Individual supply valve 2581 Plunger 2582 solenoid 2583 Spring 259 Damper 260 Intermediate tank flow path 261 Intermediate tank flow valve 262 Intermediate tank 262a Intermediate upper limit sensor 262b Intermediate reference sensor 263 Common supply valve 265 Maintenance flow path 266 Maintenance flow path Flow valve 27 Recovery flow path 270 Bypass valve 271 Check valve 272 Recovery common flow path 273 Recovery valve 274 Circulation Valve 275 Recovery pump 281-283 Check valve 29 Suction part 291 Check valve 292 Chamber 292a Liquid level sensor 293 Vacuum pump 294 Pressure sensor 30 Ink storage part 31 Main tank 32 Supply pump 35 Rack 40 Control part 401 CPU
402 RAM
403 ROM
403a Individual maintenance execution flag 404 Memory 41 Communication unit 42 Operation display unit 43 Notification operation unit 49 Bus 100 Inkjet recording device

Claims (8)

A plurality of ejection heads having nozzles for ejecting droplets,
A liquid flow path for introducing the liquid to be discharged into each of the plurality of discharge heads,
An individual opening / closing unit that switches between a communication state and a non-communication state between the liquid flow path and the plurality of discharge heads in groups of at least two or more.
A liquid feeding means for pressurizing and feeding a liquid into the discharge head via the liquid flow path,
With some of the individual opening / closing parts open, a liquid is pressurized and sent into some of the discharging heads corresponding to the part of the individual opening / closing parts to perform a discharge operation, and then all the individual opening / closing parts are performed. and pressure control means for Ru liquids to perform the spitting discarded operation by pressurized pumping fluid in all of said discharge head with opened closing portion,
A droplet ejection device comprising. The liquid flow path includes an intermediate flow path through which the liquid flows through the intermediate storage section and a bypass flow path provided in parallel with the intermediate flow path and through which the liquid flows without passing through the intermediate storage section.
The intermediate flow path is provided with an intermediate storage section opening / closing section for switching whether or not liquid can flow in or out of the intermediate storage section.
The detour flow path is provided with a detour flow path opening / closing portion for opening / closing the detour flow path.
When the liquid is pressurized and sent while the part of the individual opening / closing part is opened, the pressurizing control means closes the intermediate storage part opening / closing part and opens the detour flow path opening / closing part. The droplet ejection device according to claim 1. A decompression means for reducing the pressure of the liquid in the liquid flow path is provided.
The pressurizing control means pressurizes the liquid to the part of the discharge heads, and then pressurizes the liquid in the liquid flow path by the depressurizing means before opening all the individual opening / closing portions. The droplet ejection device according to claim 2, wherein the pressure is reduced and the opening / closing portion of the intermediate storage portion is opened. The droplet ejection device according to claim 3, wherein the depressurizing means includes a suction means for sucking the liquid in the liquid flow path. After opening the opening / closing part of the intermediate storage part, the pressurization control means sucks the liquid in the liquid flow path and the intermediate storage part so that the pressure of the liquid in the intermediate storage part becomes a predetermined set value. The droplet ejection device according to claim 4, wherein the droplet is sucked by means. A storage unit for storing the liquid to be pressurized and sent to the discharge head by the liquid feeding means, and a storage unit.
A recovery flow path that returns the liquid sucked by the suction means to the storage unit,
The droplet ejection device according to claim 4 or 5, wherein the droplet ejection device is provided. The droplet according to any one of claims 1 to 6, further comprising a pressure supply control means for dividing the pressure feed of the liquid for each discharge head having a predetermined maximum supply number or less. Discharge device. Between a plurality of discharge heads having nozzles for discharging droplets, a liquid flow path for introducing a liquid to be discharged into each of the plurality of discharge heads, and the liquid flow path and the plurality of discharge heads. A droplet discharge portion including an individual opening / closing unit for switching between a communication state and a non-communication state for each group of at least two or more, and a liquid feeding means for pressurizing and feeding a liquid into the discharge head via the liquid flow path. It ’s a device maintenance method.
With some of the individual opening / closing parts open, a liquid is pressurized and sent into some of the discharging heads corresponding to the part of the individual opening / closing parts to perform a discharge operation, and then all the individual opening / closing parts are performed. maintenance method of the droplet discharge device which comprises the pressure control step of Ru all liquid in the ejection head to perform the spitting discarded operation by pressurized pumping fluid with opened closing unit.

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