JP6690380B2 - Droplet discharging apparatus and method of controlling droplet discharging apparatus - Google Patents

Description

  The present invention relates to a droplet discharge device and a method of controlling the droplet discharge device.

  Conventionally, an ejection head (droplet ejection unit) having a nozzle for ejecting a liquid such as ink is provided, and an image is recorded or a film or a structure is formed by ejecting a droplet of the liquid onto a medium. There is a droplet discharge device. In recent years, a plurality of ejection heads are arranged to reduce the nozzle interval in response to a demand for higher accuracy of recording images and higher speed of image recording by a droplet ejection device (inkjet recording device) that ejects ink droplets, There is a device that can record an image in a wide area at once.

  In such an ink jet recording apparatus, there is a case where the specific ejection head is selectively maintained or replaced depending on the malfunction of the specific ejection head. Correspondingly, a valve such as a solenoid valve is provided in the individual flow path for introducing the liquid to be ejected into each of the ejection heads, and the liquid supply is selected for the ejection heads that do not want to supply the liquid. It is possible to selectively shut off the ink or selectively supply the ink to the ejection head to which the liquid is to be introduced (for example, Patent Document 1).

JP, 2014-141032, A

  However, a solenoid valve or the like is usually used as an electromagnetic valve used to control the flow of liquid such as ink, and an operation in one direction is electromagnetically driven, whereas an operation in the opposite direction is not. This is done using the restoring force of the spring. Therefore, when the pressure of the liquid exceeds the restoring force of the spring, the solenoid valve does not operate normally, and there is a problem that the control of the liquid flow becomes abnormal.

  An object of the present invention is to provide a droplet discharge device and a method of controlling the droplet discharge device that can more reliably control the flow of liquid.

In order to achieve the above object, the invention described in claim 1 is
A droplet discharge unit that discharges droplets,
A liquid flow path for introducing the liquid to be discharged to the droplet discharge unit,
A liquid feeding means for feeding a liquid between the liquid channel and the outside of the liquid channel,
An electromagnetic valve for switching whether or not the liquid can flow in a predetermined portion of the liquid flow path,
Pressure adjusting means for performing a pressure adjusting operation for reducing the pressure difference of the liquid at both ends of the solenoid valve,
When the solenoid valve operates the liquid feeding means in a non-circulation state and switches the solenoid valve to the circulation state after liquid is fed, control means for performing the pressure adjusting operation by the pressure adjusting means,
Bei to give a,
The liquid flow path has a common flow path that communicates with the liquid supply unit, and an individual flow path that branches from the common flow path and communicates with the droplet discharge unit,
The solenoid valve is provided in the individual flow path, and in the non-circulation state, the movable member is electromagnetically driven in a predetermined liquid feeding direction against the restoring force of a predetermined elastic material, and in the circulation state, Arranged in a direction to return the movable member in the opposite direction to the liquid transfer using a restoring force,
The pressure adjusting means reduces the pressure of the liquid upstream of the electromagnetic valve in the predetermined liquid feeding direction,
The droplet discharge part, the electromagnetic valve, and the individual flow paths in which the electromagnetic valve is provided are provided in a plurality corresponding to each other.
The control means performs the pressure adjustment operation by the pressure adjustment means when switching at least a part of the electromagnetic valve that was in the non-circulation state when the liquid feeding means was operated to the circulation state. The droplet discharge device is characterized in that

Further, the invention according to claim 2 is the droplet discharge device according to claim 1 ,
The predetermined elastic material is a spring.

The invention according to claim 3 provides the droplet discharge device according to claim 1 or 2 ,
The control means is characterized in that the electromagnetic valve to be switched is switched to the circulating state after a predetermined delay time has elapsed since the pressure adjusting operation by the pressure adjusting means was started.

The invention of claim 4, wherein, in the droplet ejection apparatus according to any one of claim 1 to 3
The pressure adjusting means is characterized by having an atmosphere opening valve that opens at least one end side of the electromagnetic valve in the liquid flow path to the atmosphere.

According to a fifth aspect of the present invention, in the droplet discharge device according to the fourth aspect ,
The liquid sending means comprises a storage part open to the atmosphere for storing the liquid to be sent to the liquid flow path,
The atmosphere release valve is in communication with the storage section.

The invention according to claim 6 provides the droplet discharge device according to any one of claims 1 to 5 ,
The pressure adjusting means has a suction means for sucking the liquid in the liquid flow path.

According to a seventh aspect of the invention, in the liquid droplet ejection apparatus according to the sixth aspect ,
The suction means sucks the liquid in the liquid flow path by reversing the direction of the liquid supply by the liquid supply means.

The invention according to claim 8 is
A liquid droplet ejecting unit that ejects liquid droplets, a liquid flow channel that introduces a liquid to be ejected into the liquid droplet ejecting unit, and liquid transfer that performs liquid transfer between the liquid flow channel and the outside of the liquid flow channel. Means, an electromagnetic valve for switching whether or not the liquid is allowed to flow in a predetermined portion of the liquid flow path, and a pressure adjusting means for performing a pressure adjusting operation for reducing a pressure difference between the liquids at both ends of the electromagnetic valve. The liquid flow path has a common flow path that communicates with the liquid sending unit, and an individual flow path that branches from the common flow path and communicates with the droplet discharge unit, and the electromagnetic valve is the The movable member is provided in the individual flow path and electromagnetically drives the movable member in a predetermined liquid feeding direction against a restoring force of a predetermined elastic material in the non-circulation state, and uses the restoring force to restore the movable member in the circulation state. Is arranged in a direction in which the liquid is returned in a direction opposite to the liquid feeding, and the pressure adjusting means is Reduce the pressure on the upstream side of the liquid from the solenoid valve for countercurrent, the droplet discharge unit, wherein the individual channel to the solenoid valve and the solenoid valve is provided, the droplet discharge device which is provided by a plurality to correspond to each other Control method of
The solenoid valve is operated said feeding means in a non-flowing state, when switching the flow state the solenoid valve after being fed, saw including a control step of causing the pressure adjustment operation by the pressure regulating means,
In the control step, the pressure adjusting operation is performed by the pressure adjusting means when at least a part of the electromagnetic valve that is in the non-circulation state when the liquid feeding means is operated is switched to the circulation state. It is characterized by causing.

  According to the present invention, there is an effect that it is possible to more reliably control the flow of liquid in the droplet discharge device.

FIG. 1 is an overall perspective view of an inkjet recording device. FIG. 3 is a diagram illustrating a configuration related to an ink flow path in the inkjet recording device. It is a figure which shows the example of the cross-section of an individual supply valve. FIG. 3 is a block diagram showing a functional configuration of an inkjet recording device. It is a figure explaining the pressure change of ink. It is a flow chart which shows the control procedure of individual maintenance processing. It is a flow chart which shows the control procedure of other examples of individual maintenance processing.

Embodiments of the present invention will be described below with reference to the drawings.
FIG. 1 is an overall perspective view of an inkjet recording apparatus 100 that is one of the embodiments of the droplet discharge apparatus of the present invention.

  The inkjet recording apparatus 100 is a one-pass type apparatus 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 carry motor 12 rotates the drive roller 11 at a predetermined speed. An endless conveyor belt 14 is wound around the drive roller 11 together with a driven roller (not shown), and the conveyor belt 14 is rotated by the rotation of the drive roller 11. A 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 moves around.

  The image forming unit 20 includes a carriage 22, a carriage elevating / lowering unit 23, a reading unit 24, and the like, and the combination of the carriage 22 and the carriage elevating / lowering unit 23 corresponds to the number of ink colors (here, eight 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 extends on the transport surface of the print medium by the transport unit 10. A plurality of inkjet heads 211 (see FIG. 2, droplet discharge unit) arranged above (in the z direction) and capable of discharging droplets of ink (liquid to be discharged) over the entire width of the recording medium to be conveyed are fixed. Has been 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 to the upper side can be changed by the carriage elevating / lowering unit 23, and the inkjet head 211 also changes the distance from the transport surface as the carriage 22 moves.

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

  The lifting motor 232 moves the carriage 22 at a predetermined lifting speed. As the lifting 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 when the fixed state is released in response to a drive signal, the lift motor 232 can temporarily move the carriage 22. That is, the electromagnetic brake 233 fixes the carriage 22 in a normal state including when the power is turned off. 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 imaging element arranged so as to be able to image the surface of the recording medium over the recordable width of the recording medium. As the line sensor, a known one such as a CCD sensor or a CMOS sensor is used. It is possible to capture a two-dimensional image on the recording medium by sequentially capturing the recording medium in the width direction while transporting the recording medium in the transport direction, and the captured data is sequentially transmitted to the control unit 40. It is used for inspection of recorded images.

  The ink storage unit 30 stores ink of each color used for image recording and supplies the ink to the inkjet head 211. Here, each component of the ink storage unit 30 is arranged on 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 relating to the ink flow path (liquid flow path) from the ink storage section 30 to the image forming section 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 device 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 the respective ink colors and 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 replaceable in its entirety and is detachably attached to the ink flow path to the supply pump 32 regardless of the operating state of the supply pump 32. That is, the main tank 31 is attached while the supply pump 32 is in an operating state, so that the liquid supply of ink to the image forming unit 20 is immediately restarted.
The supply pump 32 is not particularly limited, but, for example, a diaphragm pump or a tube pump 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). An ink flow path (circulation flow path) that returns to the sub tank 251 again after the ink sent from the sub tank 251 reaches the inkjet head 211 is provided for the sub tank 251.

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

Between the degassing module 255 and the liquid sending common flow path 256, the ink flow path branches into an intermediate tank flow path 260 and a maintenance flow path 265. The intermediate tank flow path 260 is provided with an intermediate tank flow valve 261, an intermediate tank 262, a common supply valve 263, and the like.
A maintenance flow passage circulation valve 266 is provided in the maintenance flow passage 265.

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

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

  The capacity of the sub tank 251 is not particularly limited, but is smaller than the capacity of the main tank 31 here. The sub tank 251 is provided with a reference sensor 251a, a lower limit sensor 251b, an upper limit sensor 251c and the like for detecting the ink storage amount. The reference sensor 251a detects whether or not a standard storage 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 is prohibited is stored. That is, the lower limit storage amount is smaller than the standard storage amount, and when the ink storage amount is smaller than the lower limit storage amount, the operation of the inkjet head 211 (ink ejection) 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 significantly decrease from the standard storage amount. Therefore, if the ink amount is less than the lower limit storage amount, the ink supply is not performed normally. Means the occurrence of.

The upper limit sensor 251c detects whether or not the upper limit storage amount of ink indicating the risk of overflow of 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 paths (the liquid supply flow path, the inkjet head 211, and the recovery flow path 27), that is, the ink is the nozzles of the inkjet head 211. Even if all are returned to the sub-tank 251 without being ejected from any of the above, the upper limit storage amount is not exceeded. Therefore, exceeding the upper limit storage amount may cause an abnormal situation such as excessive ink supply or mixing with something other than ink. 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 about atmospheric pressure.

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

The liquid sending pump 253 sends the ink inside the sub-tank 251 to the filter 254 or the downstream side thereof, that is, the inkjet head 211 side (liquid sending flow path) at a predetermined liquid sending speed (liquid sending amount per time). Here, one liquid feed pump 253 is provided for the sub-tank 251, and supplies ink to all the inkjet heads 211. However, a plurality of blocks are formed for each predetermined number of inkjet heads 211, and separate liquid feed pumps are provided. Ink may be supplied from the sub tank 251 by the liquid pump 253. The liquid feeding pump 253 may have a liquid feeding capacity as long as it can sufficiently supply the maximum ink ejection amount per hour by the inkjet head 211 in accordance with the image recording operation, and the ink feeding speed according to the maximum ink ejection amount. Is smaller than the maximum liquid feed 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 feed pump 253 at the maximum ink feed speed even in the situation where the ink is ejected most from the inkjet head 211 (such as during recording of a solid image).
Further, the liquid feed pump 253 can pressurize and feed the ink having the ink ejection capacity or higher to the inkjet head 211. That is, the ink in the liquid-sending common flow path 256, the individual flow paths 257, and the inkjet head 211, to which the ink has been sent, is temporarily set to a state higher than atmospheric pressure.

  The filter 254 removes foreign matters such as dust and dust, foreign matters, large air bubbles, and the like in the ink. As described above, the sub tank 251 is open to the atmosphere, and these foreign substances, foreign matters, and air bubbles may be mixed. Therefore, the filter 254 prevents these 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 ink in the ink is brought into contact with the vacuum region via a degassing film to selectively suck the air in the ink to the vacuum region side. The deaeration film may have, for example, a large number of hollow fine yarn structures in which the inside is in a vacuum state in order to efficiently increase the contact area with the ink and contact the ink more uniformly.
Here, the air on the vacuum region side of the degassing module 255 is sucked by the vacuum pump 293. The vacuum region here does not necessarily have to be an ultrahigh vacuum, and a predetermined atmospheric pressure sufficiently lower than atmospheric pressure is preset. The pressure sensor 294 measures the atmospheric pressure on the vacuum region side, and the operation of the vacuum pump 293 is controlled according to the measurement 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. The ink that slightly permeates the deaeration film or leaks to the vacuum region side at once when the deaeration film is broken, 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 is leaked. When an abnormality is detected, the operation of the vacuum pump 293 or each unit is stopped, or the vacuum region is exposed to the atmosphere. It is communicated. In this way, the chamber 292 is used as a trap for the leaked ink, and the leaked ink is prevented from reaching the vacuum pump 293, thereby preventing the vacuum pump 293 from being broken or damaged.

  As the liquid amount sensor 292a, in addition to a device that directly measures the liquid amount, a member that measures the weight change of the chamber 292 or that changes according to the weight change, for example, an actuator that is deformed by the load according to the weight of the chamber 292 is used. It is possible to use a device that optically, electrically, or magnetically measures a signal output according to the deformation.

  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 to the degassing module 255 in the circulation channel provided for each color ink. The structure is such that it merges downstream of the check valve 291 (on the side of the chamber 292). That is, when the 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 passage for the ink of another color. Is prevented.

The individual supply valve 258 can supply or not supply the ink from the common liquid feed channel 256 to the individual flow channels 257 that communicate with the predetermined number (two in this case) of the common liquid feed channel 256 (here, two). Yes / No), that is, switching between the circulation state and the non-circulation state of the ink (liquid) between each individual flow path 257 and the inkjet head 211. All of these individual supply valves 258 are opened during a normal image recording operation, and when the ink in the intermediate tank 262 or the liquid transfer common flow path 256 is returned to the sub tank 251 without being discharged to the outside, these individual supply valves 258 are collected. The supply valve 258 is closed and the bypass valve 270 is opened. When ink is selectively supplied to some of the inkjet heads 211 for inspection, cleaning, or maintenance of some of the inkjet heads 211, the individual flow paths 257 communicating with the some of the inkjet heads 211 are also provided. Only the individual supply valve 258 provided in the above is opened, and the other individual supply valves 258 are closed.
Here, as an example, four individual flow channels 257 and four individual supply valves 258 are described, and eight inkjet heads 211 are described. However, this number is from the supply of ink to the inkjet head 211 and the number of nozzles. Can be appropriately set by a number corresponding to each other (usually a plurality of line heads each) within a range that does not cause a problem in the ejection operation.

FIG. 3 is a diagram showing an example of a sectional structure of the individual supply valve 258 of this embodiment.
For the individual supply valve 258 and other valves for switching the presence / absence of ink flow, here, an electromagnetic valve, for example, a plunger 2581 (movable member) 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 ink flow path direction, 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 operates as a spring 2583 (elastic material). When the voltage is released by moving to the downstream side (on the side of the inkjet head 211, in the liquid feeding direction) so as to electromagnetically block the ink flow path against the restoring force (repulsive force) and the application of the voltage is released. The ink flow path moves in the direction opposite to the liquid feeding direction according to the restoring force of the ink, returns to the original upstream position, and the ink flow path is opened. In FIG. 2, white valves such as the individual supply valve 258 are valves that are opened in a normal state (when the ground voltage is supplied or when the voltage is not supplied), and the intermediate tank flow valve 261 is painted black. The valve is a valve that is closed in the normal state.

  The damper 259 is a buffer unit that reduces pressure fluctuations that occur depending on the ink ejection status from the plurality of inkjet heads 211 and the liquid delivery status from the liquid delivery pump 253. The damper 259 is provided with a flexible film or the like, and suppresses its ripples by bending due to pressure fluctuations related to the operation of the other inkjet head 211 and the liquid feed pump 253, and when ejecting ink from the inkjet head 211, The ink is normally ejected by applying pressure to the ink in the inkjet head 211 with an appropriate pressure pattern. 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.

  The inkjet head 211 has a plurality of nozzles arranged therein. 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 the ink flow path, and ink is ejected by applying a pressure with an appropriate waveform to the ink in the pressure chamber, or ink not ejected is appropriately vibrated in the nozzle. This prevents the ink from drying or degrading. The method of pressurizing the ink in the pressure chamber can be selected from various well-known ones. Here, the pressure of the ink is changed by deforming the pressure chamber by applying a voltage using a piezoelectric element or a vibration plate. It has a piezo-type configuration. The ink surface (meniscus) is appropriately maintained near the opening of each nozzle. As a result, when pressure is applied, droplets having an appropriate shape and size are separated from the ink in the nozzles and ejected.

  The check valve 271 allows the ink discharged from the inkjet head 211 without being ejected from the nozzles 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. Prevent backflow. That is, the ink discharged from some inkjet heads 211 does not flow back to the other inkjet heads 211.

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

  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, that is, a pressure (negative pressure) lower than atmospheric pressure. For this reason, the intermediate tank 262 is formed of a flexible material, can be appropriately deformed by the pressure difference between the ink pressure and the external atmospheric pressure, and is formed from the nozzle surface on which the nozzle openings of the inkjet head 211 are arranged. Is also provided at a slightly lower position in the vertical direction. As a result, the ink does not spontaneously leak from the nozzle opening except when the ink is intentionally ejected by further applying pressure to the ink in the liquid feed pump 253 or the pressure chamber in the inkjet head 211. . On the other hand, when ink is ejected from the nozzle openings and the ink in the inkjet head 211 decreases, the ink flows from the intermediate tank 262 to the inkjet head 211 according to the decrease 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 set appropriately to obtain an appropriate back pressure (that is, indirectly, an appropriate back pressure itself). Whether or not the liquid feed pump 253 operates is appropriately controlled according to whether or not the intermediate reference ink amount of the intermediate reference sensor 262b is detected. Further, the intermediate upper limit sensor 262a detects the upper limit ink amount that is determined so as not to be dangerous for maintaining the intermediate tank 262. Normally, when the ink amount in the intermediate tank 262 rises above the normal level and the ink pressure rises, the check valve 283 is opened and the ink is returned to the sub tank 251, but the check valve 283 does not function normally. For example, depending on the detection by the intermediate upper limit sensor 262a, it is possible to stop all the processes related to the ink supply operation or perform other appropriate processes.

  The maintenance channel flow valve 266 switches whether or not the ink delivered by the liquid delivery pump 253 can flow into the maintenance channel 265. As shown here, the maintenance channel flow valve 266 and the intermediate tank flow valve 261 may be closed at the same time. For example, even during the image recording operation, when the ink amount in the intermediate tank 262 is within an appropriate range and the ink is not additionally supplied to the intermediate tank 262 by the liquid feeding pump 253, the maintenance flow passage The valve 266 and the intermediate tank flow valve 261 are both closed.

  The maintenance flow path 265 is pressurized and sent by the liquid sending pump 253 to the liquid sending common flow path 256 and the inkjet head 211 for the purpose of introducing ink, discharging air (air bubbles), and flushing out the cause 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 common liquid sending channel 256, and the ink is made to flow to the inside. The air is discharged to the recovery passageway 27 and the sub tank 251. In addition, the pressurized ink is sent out by the liquid sending pump 253 with both the individual supply valve 258 and the recovery valve 273 opened, so that the ink flow path in each inkjet head 211 is filled with ink. In addition, the pressurized ink is delivered by the liquid delivery pump 253 with a part or all of the individual supply valves 258 opened and the recovery valve 273 closed, so that the ink pressurized from each nozzle of the inkjet head 211 is discharged. Is discharged to discharge air bubbles in the nozzles, and at the same time, the cause of clogging of the nozzle openings and the like, for example, solidified or thickened ink lumps are discharged to eliminate clogging. At this time, by reducing the number of individual supply valves 258 to be opened, it is possible to increase the pressure of the ink supplied to the inkjet head 211 related to the individually opened individual supply valves 258.

  The common supply valve 263 is switched from the intermediate tank 262 to the liquid supply common flow path 256 and each ink jet head 211, and is closed so that the common supply valve 263 is particularly pressurized through the maintenance flow path 265. It prevents the ink from flowing back to the intermediate tank 262 when the ink is supplied to the common flow path.

  The recovery common flow channel 272, which merges the ink discharged without being ejected from the inkjet head 211 and flows to the sub-tank 251 side, has substantially the same configuration as the liquid delivery common flow channel 256, and is formed in a tube shape, for example. ing. The liquid-sending common flow path 256 and the recovery common flow path 272 are both formed to be sufficiently thicker (having a larger cross-sectional area) than the individual flow path 257, so that the flow rate relating to the change in the ink supply amount to the individual flow path 257 is increased. Also, it is possible to prevent the influence of the change in the ink pressure from spreading.

  The recovery valve 273 switches whether to return the ink from the recovery common channel 272 to the sub tank 251. Further, the recovery valve 273 is closed when the bypass valve 270 is opened, so that the ink flowing from the liquid delivery 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 (suction unit). When the ink that has been once delivered from the liquid delivery pump 253 and has not been ejected from the nozzles of the inkjet head 211 is extracted 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 such as the inkjet head 211 and the intermediate tank 262 is sucked and returned to the sub tank 251, thereby reducing the amount of ink inside the inkjet head 211 and the intermediate tank 262 (that is, The pressure adjustment operation (pressure reduction) by the ink is performed), and further, the ink can be removed.
As described above, since the sub tank 251 is open to the atmosphere, the bypass valve 270 and the circulation valve 274 are opened to open the common liquid sending channel 256 and the individual flow channel 257 to the atmosphere. That is, the bypass valve 270 and the circulation valve 274 form an atmosphere opening valve, and the atmosphere opening valve and the recovery pump 275 form a pressure adjusting means.

  Further, the recovery pump 275 sucks not only the ink but also the air in the ink flow path. When the ink is not supplied to the circulation flow path at the time of restart such as in the initial state or after maintenance, the recovery pump 275 once sucks the air in the circulation flow path, and in particular, almost eliminates the air in the intermediate tank 262. After completely removing the ink, the ink is introduced into the intermediate tank 262 by the liquid feed pump 253, whereby air remains in the intermediate tank 262 to generate unnecessary pressure, or the air is mixed with the ink. It is possible to avoid the occurrence of ejection failure or the like due to the outflow and being sent to the inkjet head 211. Normally, at the time of introducing the ink, by repeating the removal of air by the recovery pump 275, the recovery of the ink and the introduction of the ink by the liquid feeding pump 253 a plurality of times, the circulation flow path, particularly, from the sub tank 251 to the inkjet head 211 is It becomes possible to introduce the ink while more surely preventing air from remaining during the period.

  When it is not necessary to remove the ink inside the inkjet head 211 or the intermediate tank 262, and when the ink sent by the liquid sending pump 253 is simply circulated, the recovery pump 275 is not operated and the circulation valve 274 is opened. As a result, a circulating flow of ink is generated only by the liquid feed pressure of the liquid feed pump 253.

  A discharge valve is provided on the downstream side of the filter 254, on the downstream side of the intermediate tank 262, and on the common liquid-feeding channel 256 so that the user can open and discharge the ink as needed.

Next, the functional configuration of the inkjet recording apparatus 100 of this embodiment will be described.
FIG. 4 is a block diagram showing the functional configuration of the inkjet recording apparatus 100.
The inkjet recording apparatus 100 includes the supply pump 32, the liquid feed pump 253, the recovery pump 275, the vacuum pump 293, the reference sensor 251a, the lower limit sensor 251b, the upper limit sensor 251c, the intermediate upper limit sensor 262a, the intermediate reference sensor 262b, and the pressure sensor 294. , Liquid amount sensor 292a, intermediate tank flow valve 261, maintenance channel flow valve 266, common supply valve 263, individual supply valve 258, recovery valve 273, circulation valve 274, electromagnetic brake 233, lifting motor 232, and reading unit 24. In addition, the control unit 40 (control unit), the communication unit 41, the operation display unit 42, the conveyance motor 12, the head drive unit 221, the motor driver 231, the notification operation unit 43 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 and controls the recording medium conveyance, ink supply, ink ejection, maintenance operation, and the like in the inkjet recording apparatus 100. Further, the CPU 401 performs various processes related to image recording based on image data, a status signal of each part, a clock signal, and the like according to a 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 programs related to ink supply control and maintenance operation of the inkjet recording apparatus 100.

  In addition, the ROM 403 includes a non-volatile memory that can be overwritten and updated, and stores an individual maintenance execution flag 403a that indicates whether or not individual maintenance, which will be described later, has been executed. The memory 404 includes a RAM that temporarily stores image data to be recorded.

The head drive unit 221 generates and outputs a drive voltage signal for deforming the pressure chamber (piezoelectric element) in order to properly eject ink from the nozzles of each inkjet head 211. The head drive section 221 selects a voltage waveform pattern stored in advance on the basis of a control signal from the control section 40 to generate a drive voltage signal which is power-amplified, and according to the image data input from the memory 404. Whether to output the drive voltage signal 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 also partially formed separately.

  The motor driver 231 outputs a drive signal to the electromagnetic brake 233 and the elevating motor 232 according 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. As the communication interface, for example, one or a plurality of interfaces corresponding to various communication protocols such as a LAN board and a LAN card are included. The communication unit 41 acquires image data to be recorded and setting data (job data) related to image recording from an external device under 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 apparatus 100, an operation menu, and the like in response to a control signal from the control unit 40, and receives a user 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 unit is provided so as to overlap a display screen as a display unit. The control unit 40 causes the liquid crystal display unit to display various menus and the like for accepting commands by the status and the touch sensor, and the contents and position information of the displayed menu and the touch operation of the user detected by the touch sensor. A control operation is performed to cause each unit of the inkjet recording apparatus 100 to perform a corresponding process.

The notification operation unit 43 performs a predetermined notification operation according to the control signal from 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 generator that generates a beep sound.
In addition to these, the inkjet recording apparatus 100 may include a placement abnormality detection sensor that detects that the supplied recording medium is not properly placed on the transport surface.

  The bus 49 is a path for electrically connecting the above-described components to exchange signals.

Next, a 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 ink of the inkjet head 211 is temporarily removed or refilled, when the nozzle of the inkjet head 211 is clogged, or when air bubbles or the like are mixed, the ink is normally printed. When it is no longer possible to eject the ink, maintenance processing is performed such that the inkjet head 211 is caused to perform an ink suction operation or pressure-feeding.

  At this time, if the liquid is fed under pressure by the liquid feed pump 253, the ink pressure on the upstream side of the closed individual supply valve 258 rises, and a pressure difference occurs with the ink pressure on the downstream side. Therefore, even if the individual supply valve 258 is subsequently opened, the pressure difference becomes larger than the restoring force of the spring 2583, and the individual supply valve 258 is not normally opened. Therefore, in the ink jet recording apparatus 100 of the present embodiment, before the closed individual supply valve 258 is opened, the pressure of the ink on the upstream side is reduced (the pressure difference between the ink at both ends of the solenoid valve is reduced). Do in advance.

FIG. 5 is a diagram schematically showing a change in ink pressure.
When pressurized liquid feeding is performed with the individual supply valve 258 closed with respect to the ink pressure on the downstream side of the individual supply valve 258 indicated by the dotted line, the upstream ink pressure increases as indicated by the solid line. When the upstream side ink pressure becomes larger than the downstream side ink pressure by the pressure difference dp or more, if the individual supply valve 258 cannot be opened, the individual supply valve 258 cannot be opened immediately after the start of pressurized liquid feeding. Therefore, after the pressure-feeding is completed, the pressure reduction on the upstream side is started at the timing t1, and the opening operation of the individual supply valve 258 is performed at the timing t2 after the pressure difference between the upstream side and the downstream side falls below dp. The individual supply valve 258 is surely opened so that the ink pressures on the upstream side and the downstream side become equal.

FIG. 6 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 this embodiment.
The individual maintenance process causes the problem, for example, when a problem such as defective ink ejection is detected as a result of manual analysis by a predetermined input operation by a user or imaging and analysis of a predetermined inspection image. It is automatically executed for the inkjet head 211 including the nozzle. It is preferable that the inspection image is provided with 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 (CPU 401) closes the common supply valve 263 (step S101). Further, the control unit 40 closes the intermediate tank flow valve 261 and opens the maintenance channel flow valve (step S102). As a result, the intermediate tank 262 is separated from the ink flow path from the liquid supply pump 253 to the liquid supply common flow path 256.

  The control unit 40 closes the individual supply valve 258 that communicates with the inkjet head 211 that is not the target of pressure-feeding (step S103). The control unit 40 operates the liquid feed pump 253 to feed the ink under pressure to the inkjet head 211, which is the target of pressurized liquid feed (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 heads 211 can flow out only from the nozzle openings of each inkjet head 211, and the nozzles of the inkjet heads 211 are clogged. And bubbles are pushed out from the nozzle opening.

  The control unit 40 opens the bypass valve 270 and the circulation valve 274 to release the pressure in the liquid sending common flow path 256 and the inkjet head 211, which has been increased by the operation of the liquid sending pump 253, to the sub tank 251 which is open to the atmosphere. The pressure is reduced (step S105; control step). The control unit 40 determines whether or not the liquid supply to all the inkjet heads 211 to which the liquid is pressurized is completed (step S106).

  When it is determined that the liquid transfer is not completed (“NO” in step S106), the control unit 40 opens the bypass valve 270 and the circulation valve 274 for a predetermined time (a predetermined delay time). It is determined whether or not (step S117). When it is determined that the time has not elapsed (“NO” in step S117), the control unit 40 repeats the determination process of step S117.

  When it is determined that the predetermined time has elapsed (“YES” in step S117), the control unit 40 opens the individual supply valve 258 for the next pressurized liquid-sending target (switch target) and other individual supply valves. 258 is closed (step S118). The control unit 40 closes the bypass valve 270 and the circulation valve 274 (step S119). Then, the process of the control unit 40 returns to step S104.

  When it is determined that the ink has been pressure-fed into the ink flow paths of all the inkjet heads 211 to be pressure-fed (“YES” in step S <b> 106), the control unit 40 turns on the maintenance flow-path circulation valve 266. The intermediate tank flow valve 261 and the common supply valve 263 are closed (step S107). As a result, the ink pressure in the intermediate tank 262 rises in accordance with the amount of the pressure of the ink in the liquid sending 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 circulation valve 274 are in the open state, but the circulation valve 274 may be closed. The controller 40 operates the recovery pump 275 to suck the ink in the intermediate tank 262 and adjust the pressure (ink amount) in the intermediate tank 262 to the set value (step S109).

  The control unit 40 closes the bypass valve 270 and the circulation valve 274 and opens all the individual supply valves 258 (step S110). The control unit 40 operates the liquid feed pump 253 to pressurize and feed the ink to all the recording heads to eject the ink from each nozzle, and form the meniscus of the liquid level in each nozzle into an appropriate shape. (Step S111). Then, the control unit 40 ends the individual maintenance process.

FIG. 7 is a flowchart showing a control procedure by the control unit 40 of another example of the individual maintenance process.
This individual maintenance process is different from the individual maintenance process of the above-described embodiment except that the process of step S115 is added and the processes of steps S109 and S110 are replaced with the processes of steps S109a and S110a, respectively. The same processing contents are designated by the same reference numerals and the description thereof will be omitted.

  After the liquid feed pump 253 is operated to pressurize and feed the ink in the process of step S104, the control unit 40 reversely operates the liquid feed pump 253 for a predetermined time to pull back the pressurized and fed ink (step S115). ). After that, the control unit 40 opens the bypass valve 270 and the circulation valve 274 (step S105). In addition, a predetermined delay time may be provided from the start of the reverse rotation operation of the liquid feed pump 253 to the opening of the bypass valve 270 and the circulation valve 274.

  In addition, after all the individual supply valves 258 are closed in the process of step S108, the control unit 40 closes the bypass valve 270 and the circulation valve 274, and then operates the liquid feed pump 253 in the reverse direction to set the ink flow path and the ink flow path. The ink once supplied to the inkjet head 211 is pulled back to adjust the amount of ink in the intermediate tank 262 (step S109a). The control unit 40 opens all the individual supply valves 258 (step S110a), and then shifts the processing to step S111.

  In the inkjet recording apparatus 100 of the present embodiment, when the liquid feed pump 253 is operated in the reverse direction, the ink to be drawn back passes through the degassing module 255 and the filter 254. A detouring reverse flow path for returning ink to 251 may be provided so that switching can be selected between normal liquid feeding and reverse operation.

As described above, the inkjet recording apparatus 100 according to the present exemplary embodiment includes the inkjet head 211 that ejects ink droplets, the common liquid flow path 256 that introduces the ink to be ejected into the inkjet head 211, and the individual flow path 257 ( Collectively, an ink flow path), a liquid feed pump 253 that feeds ink between the ink flow path and the outside of the ink flow path (here, the sub tank 251, etc.), and the ink in a predetermined portion of the ink flow path. Individual supply valve 258, which is a solenoid valve for switching whether or not to distribute, and a bypass valve 270, a circulation valve 274, and a recovery pump as pressure adjusting means for performing a pressure adjusting operation for reducing a pressure difference of ink at both ends of the solenoid valve. 275 and the liquid feed pump 253, and the solenoid valve are in the non-circulation state, the liquid feed pump 253 is operated to feed the ink. When switching the solenoid valve to the circulation state, it comprises a control unit 40 to perform a pressure adjustment operation by the pressure regulating means.
As a result, it is possible to eliminate the pressure difference that interferes with the operation of the plunger 2581 depending on the restoring force of the spring 2583 at both ends of the solenoid valve when the solenoid valve is closed. Ink flow can be controlled.

Further, the solenoid valve (individual supply valve 258) electromagnetically drives the plunger 2581 in a predetermined liquid feeding direction against the restoring force of the spring 2583 in the non-circulating state, and uses the restoring force in the circulating state. The pressure adjusting means is arranged so as to return the plunger 2581 in the direction opposite to the liquid feeding direction, and the pressure adjusting means reduces the pressure of the ink on the upstream side of the solenoid valve in the liquid feeding direction.
Therefore, when the electromagnetic valve is temporarily closed for the ink supplied from the upstream side, the opening operation for opening the electromagnetic valve can be performed more reliably.

  In addition, by returning the position of the plunger 2581 using the spring 2583, normally, the electric power is not required to move the plunger 2581 to the initial position and keep the plunger 2581 at the initial position. Further, the gap (spring) of the spring 2583 itself can minimize the influence (resistance) on the ink flow when opening.

  Further, the ink flow path has a liquid sending common flow path 256 that communicates with the liquid sending pump 253, and an individual flow path 257 that branches from the liquid sending common flow path 256 and communicates with the inkjet head 211. The individual channels 257 are provided. That is, the solenoid valve (individual supply valve 258) switches whether or not ink can be supplied to each inkjet head 211. By performing this opening / closing operation more reliably, the ejection and outflow of ink from the inkjet head 211 can be performed. It can be controlled more appropriately.

Further, the inkjet head 211, the individual supply valve 258, and a plurality of individual channels 257 in which the individual supply valve 258 is provided are provided corresponding to each other, and the control unit 40 operates when the liquid feed pump 253 is operated. When at least a part of the individual supply valve 258 that has been in the non-circulation state is switched to the circulation state, the pressure adjusting operation is performed by the pressure adjusting means.
In this manner, by closing some of the individual supply valves 258 and supplying and supplying the ink from the liquid supply pump 253, the ink in the liquid supply common flow path 256 that is on the upstream side of the closed individual supply valves 258. The pressure easily rises locally, and particularly when the pressurized ink is fed for individual maintenance or the like, the ink pressure of the liquid feeding common flow path 256 greatly rises. Normally, it becomes difficult to reopen the closed individual supply valve 258. Therefore, after such individual maintenance, the individual supply valve 258 can be surely opened to appropriately control the ink flow, and the ink can be normally ejected from the recording head.

Further, the control unit 40 switches the solenoid valve to be switched to the circulating state after a predetermined time (a predetermined delay time) has elapsed since the pressure adjusting operation by the pressure adjusting means was started.
That is, since the electromagnetic valve is opened after the pressure difference that prevents the opening of the electromagnetic valve is sufficiently reduced, the operation of the electromagnetic valve can be reliably performed without delay.

  Further, the pressure adjusting means has a bypass valve 270 and a circulation valve 274 for opening at least one end side of the individual supply valve 258 in the ink flow path (liquid supply common flow path 256) to the atmosphere. That is, since the increased ink pressure is reduced to near atmospheric pressure to reduce the pressure difference between the both ends of the individual supply valve 258, the configuration relating to pressure reduction does not become a large scale, and the individual supply valve 258 is adjusted easily and surely. It can be opened.

  Further, the liquid feed pump 253 includes a sub-tank 251 opened to the atmosphere for storing ink to be fed to the ink flow passage (liquid feed common passage 256), and the bypass valve 270 and the circulation valve 274 make it possible to use the liquid feed common passage 256. Communicate with the sub tank 251. As a result, as described above, the pressure difference between the both ends of the individual supply valve 258 can be easily reduced at the atmospheric pressure, and the ink flowing out when the pressure difference is released can be returned to the sub tank 251. The amount of ink consumed can be reduced and waste can be suppressed.

  Further, since the recovery pump 275 for sucking the ink in the liquid sending common flow path 256 is provided, the pressure of the liquid sending common flow path 256 is reduced more reliably and promptly, and the individual supply valve 258 is opened reliably. You can

  Further, by reversing the direction of the liquid feed by the liquid feed pump 253, the ink in the liquid feed common flow path 256 can be sucked and the pressure of the ink can be reduced, whereby a new configuration is not included, or It is also possible to reduce the pressure of the liquid sending common flow path 256 to ensure the opening of the individual supply valve 258.

  Further, in the ink jet recording apparatus 100, the pressure difference between both ends of the solenoid valve (individual supply valve 258) is reduced by the control method described above, so that the restoring force of the spring 2583 is applied to both ends of the solenoid valve when the solenoid valve is closed. The pressure difference that hinders the operation of the plunger 2581 can be eliminated, and the solenoid valves can be operated more reliably to control the flow of ink.

The present invention is not limited to the above embodiment, and various modifications can be made.
For example, in the above-described embodiment, the liquid supply common flow path 256 and the individual flow path 257 are provided as the ink flow paths, and in order to reliably perform the opening operation of the individual supply valve 258 provided in the individual flow path 257, The configuration has been described as an example in which the pressure of the pressurized ink on the liquid delivery common flow path 256 side of the individual supply valve 258 is reduced, but the invention is not limited to this.
For example, the present invention can be applied to an electromagnetic valve provided in the liquid sending common flow path 256, and not only the flow path shape divided from one liquid sending common flow path 256 into all the individual flow paths 257. Alternatively, the flow path configuration may have other shapes.

  The same applies not only when the ink is supplied to the upstream side of the solenoid valve and pressurized, but also when the downstream side of the solenoid valve is depressurized by discharging the ink on the downstream side. Also, when the solenoid valve is placed in the opposite direction, the same problem occurs when the upstream side is depressurized or the downstream side is pressurized, and similarly the voltage adjustment means reduces the voltage difference across the solenoid valve. By doing so, the solenoid valve can be surely opened.

  Further, in the above-described embodiment, the problem has been described in which, when a part of the plurality of individual supply valves 258 is opened, the other part of the closed individual supply valves 258 is opened. Even if all the individual supply valves 258 are closed, if the additional ink is supplied to the liquid sending common flow path 256 and the pressure rises, it becomes difficult to open the individual supply valves 258. It is possible to Therefore, the number of the individual supply valves 258 and the ratio of the closed individual supply valves 258 are not limited to those in the above embodiment.

  Further, in the above-described embodiment, in the individual supply valve 258, the plunger 2581 moved to the closed position by the spring 2583 is returned to the open position, but another elastic material having a restoring force (repulsive force) to return to the open position is used. It may be used.

  In the above embodiment, the case where the liquid feed pump 253 or the recovery pump 275 is used as the liquid feed means and the pressure adjustment means has been described as an example, but the ink is pressurized using gravity, air pressure, hydraulic pressure, or the like. A configuration capable of reducing the pressure may be used.

  Further, in the above-described embodiment, the individual supply valve 258 is set to be opened / closed by the control of the control unit 40, but the user may specify the individual supply valve 258 to be opened / closed for input operation. In this case, if there is an instruction to open the temporarily closed individual supply valve 258, the above-described pressure adjustment (pressure reduction) operation may be performed.

Further, in the above-described embodiment, the pressure reducing operation is first performed to sufficiently reduce the pressure and then the opening operation of the individual supply valve 258 is performed. However, the pressure reducing operation and the opening operation of the individual supply valve 258 are performed simultaneously. Alternatively, the opening operation of the individual supply valve 258 may be performed immediately before. In this case, the individual supply valve 258 is not opened until the pressure is sufficiently reduced by the pressure reducing operation, but by performing the pressure reducing operation, the individual supply valve 258 is surely opened eventually.
Further, in the above-described embodiment, the opening operation of the individual supply valve 258 is performed after a lapse of a predetermined time after the depressurization operation is started, but the internal pressure of the liquid sending common flow path 256 or the like is actually measured, and The opening operation may be performed after the pressure is within a predetermined range.

  Further, in the above-described embodiment, the ink jet recording apparatus 100 having the circulation flow path capable of returning the ink to the sub tank 251 from the ink jet head 211 through the recovery valve 273 or the liquid sending common flow path 256 through the bypass valve 270 will be described. However, the present invention is not limited to this, and the ink that has been once fed from the sub tank 251 may be discharged or discarded if it is not ejected.

  Further, in the above-described embodiment, the one-pass type inkjet recording apparatus including the line head has been described as an example, but the present invention is not limited to this. It may be a scan type ink jet recording device that records an image while scanning the ink jet head 211, or a multi-pass type ink jet recording device.

The ejected ink is not particularly limited, and may be, for example, a colorless coating ink or a liquid for forming a predetermined structure other than for image recording. Further, it is not limited to the inkjet recording device, and may be various liquid droplet ejection devices that eject a liquid droplet of a liquid other than ink from a nozzle to obtain a film or a structure.
In addition, the configurations, arrangements, control contents, procedures, and the like shown in the above-described embodiment can be appropriately changed without departing from the spirit of the present invention.

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 Unit 231 Motor Driver 232 Elevating Motor 233 Electromagnetic Brake 234 Beam Member 235 Supporting Unit 24 Reading Unit 251 Sub Tank 251a Reference sensor 251b Lower limit sensor 251c Upper limit sensor 252 Flow meter 253 Liquid sending pump 254 Filter 255 Degassing module 256 Liquid sending common flow channel 257 Individual flow channel 258 Individual supply valve 2581 Plunger 2582 Solenoid 2583 Spring 259 Damper 260 Intermediate tank flow channel 261 Intermediate tank flow valve 262 Intermediate tank 262a Intermediate upper limit sensor 262b Intermediate reference sensor 263 Common supply valve 265 Maintainer Flow channel 266 maintenance flow channel circulation valve 27 recovery flow channel 270 bypass valve 271 check valve 272 recovery common flow channel 273 recovery valve 274 circulation valve 275 recovery pumps 281-283 check valve 29 suction section 291 check valve 292 chamber 292a Liquid amount sensor 293 Vacuum pump 294 Pressure sensor 30 Ink storage unit 31 Main tank 32 Supply pump 35 Rack 40 Control unit 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 droplet discharge unit that discharges droplets,
A liquid flow path for introducing the liquid to be discharged to the droplet discharge unit,
A liquid feeding means for feeding a liquid between the liquid channel and the outside of the liquid channel,
An electromagnetic valve for switching whether or not the liquid can flow in a predetermined portion of the liquid flow path,
Pressure adjusting means for performing a pressure adjusting operation for reducing the pressure difference of the liquid at both ends of the solenoid valve,
When the solenoid valve operates the liquid feeding means in a non-circulation state and switches the solenoid valve to the circulation state after liquid is fed, control means for performing the pressure adjusting operation by the pressure adjusting means,
Bei to give a,
The liquid flow path has a common flow path that communicates with the liquid supply unit, and an individual flow path that branches from the common flow path and communicates with the droplet discharge unit,
The solenoid valve is provided in the individual flow path, and in the non-circulation state, the movable member is electromagnetically driven in a predetermined liquid feeding direction against the restoring force of a predetermined elastic material, and in the circulation state, Arranged in a direction to return the movable member in the opposite direction to the liquid transfer using a restoring force,
The pressure adjusting means reduces the pressure of the liquid upstream of the electromagnetic valve in the predetermined liquid feeding direction,
The droplet discharge part, the electromagnetic valve, and the individual flow paths in which the electromagnetic valve is provided are provided in a plurality corresponding to each other.
The control means performs the pressure adjustment operation by the pressure adjustment means when switching at least a part of the electromagnetic valve that was in the non-circulation state when the liquid feeding means was operated to the circulation state. A liquid droplet ejecting device, characterized in that It said predetermined elastic material, a liquid droplet ejection apparatus according to claim 1, characterized in that it is a spring. Said control means of claim 1 or 2, wherein the switching the solenoid valve of the switching target from to initiate the pressure adjustment operation after a predetermined delay time due to the pressure adjusting means to the fluid communication Droplet ejection device. The pressure adjusting means, at least one end The apparatus according side in any one of claim 1 to 3, characterized in that it has the air release valve for air release of the solenoid valve in the liquid flow path . The liquid sending means comprises a storage part open to the atmosphere for storing the liquid to be sent to the liquid flow path,
The droplet discharge device according to claim 4 , wherein the atmosphere release valve communicates with the storage section. The pressure adjusting means, The apparatus according to any one of claim 1 to 5, characterized in that it comprises a suction means for sucking the liquid in the liquid flow path. 7. The droplet discharge device according to claim 6 , wherein the suction unit sucks the liquid in the liquid flow path by reversing the direction of the liquid supply by the liquid supply unit. A liquid droplet ejecting unit that ejects liquid droplets, a liquid flow channel that introduces a liquid to be ejected into the liquid droplet ejecting unit, and liquid transfer that performs liquid transfer between the liquid flow channel and the outside of the liquid flow channel. Means, an electromagnetic valve for switching whether or not the liquid is allowed to flow in a predetermined portion of the liquid flow path, and a pressure adjusting means for performing a pressure adjusting operation for reducing a pressure difference between the liquids at both ends of the electromagnetic valve. The liquid flow path has a common flow path that communicates with the liquid sending unit, and an individual flow path that branches from the common flow path and communicates with the droplet discharge unit, and the electromagnetic valve is the The movable member is provided in the individual flow path and electromagnetically drives the movable member in a predetermined liquid feeding direction against a restoring force of a predetermined elastic material in the non-circulation state, and uses the restoring force to restore the movable member in the circulation state. Is arranged in a direction in which the liquid is returned in a direction opposite to the liquid feeding, and the pressure adjusting means is Reduce the pressure on the upstream side of the liquid from the solenoid valve for countercurrent, the droplet discharge unit, wherein the individual channel to the solenoid valve and the solenoid valve is provided, the droplet discharge device which is provided by a plurality to correspond to each other Control method of
The solenoid valve is operated said feeding means in a non-flowing state, when switching the flow state the solenoid valve after being fed, saw including a control step of causing the pressure adjustment operation by the pressure regulating means,
In the control step, the pressure adjusting operation is performed by the pressure adjusting means when at least a part of the electromagnetic valve that is in the non-circulation state when the liquid feeding means is operated is switched to the circulation state. A method for controlling a droplet discharge device, which comprises:

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