JP6908022B2 - Inkjet recording device - Google Patents

Description

The present invention relates to an inkjet recording device.

Conventionally, there is an inkjet recording device that forms an image by ejecting ink from a nozzle and landing it on a recording medium. Inkjet recording devices can form images on a wide variety of recording media, and are widely used from household use to large-scale image formation for industrial use.

Some of these inkjet recording devices have a configuration in which ink is moved from a main ink tank to a sub ink tank, and ink is replenished from the sub ink tank according to ink ejection in the inkjet head. In such an inkjet recording device, when the ink in the sub ink tank is depleted, the ink is replenished from the main ink tank. For example, Patent Document 1 includes an empty detection sensor that detects that the sub-ink tank is empty and a full tank detection sensor that detects that the sub-ink tank is full, and is forming an image in the inkjet head. Even so, there is disclosed a configuration in which ink is replenished from the main ink tank to the sub ink tank until the full tank is detected when the empty detection is performed.

Japanese Unexamined Patent Publication No. 2005-306005

However, when an abnormality occurs in the ink storage amount of the second tank that receives the ink supply from the first tank, which is the original ink supply source, and sends the ink to the inkjet head, the ink is empty as in the conventional case. In the ink supply control according to the detection and full tank detection, the capacity of the second tank becomes smaller than the normal increase / decrease range of the ink storage amount, and even a small abnormality must be stopped immediately. On the other hand, there is a problem that the operating efficiency is lowered by increasing the number of sensors more than necessary or increasing the capacity of the second tank.

An object of the present invention is to provide an inkjet recording apparatus capable of supplying ink to an inkjet head while dealing with an abnormality in an ink storage amount with more appropriate operating efficiency.

In order to achieve the above object, the invention according to claim 1 is
A recording head that ejects ink and
The first tank to store ink and
A second tank for storing the ink supplied from the first tank, and
A first liquid feeding means for feeding ink from the first tank to the second tank, and
One or a plurality of second liquid feeding means for feeding ink from the second tank to the recording head, and
A reference sensor for determining whether or not a predetermined standard amount of ink is stored in the second tank, and
An upper limit sensor that determines whether or not an upper limit storage amount of ink larger than the standard storage amount is stored in the second tank, and an upper limit sensor.
A lower limit sensor for determining whether or not a lower limit storage amount of ink smaller than the standard storage amount is stored in the second tank, and a lower limit sensor.
Control unit and
With
The lower limit storage amount is set to be equal to or larger than the maximum amount of ink required for forming an image in the maximum range that can be set as an image formed by the recording head.
The control unit
Whether or not the first liquid feeding means operates is determined according to the detection result of the reference sensor.
Performs a predetermined abnormality response operation according to the detection results of the upper limit sensor and the lower limit sensor.
stomach,
It is characterized in that ink ejection from the recording head is prohibited after forming an image in the process of formation at a timing when the lower limit sensor no longer detects the ink of the lower limit storage amount and before starting formation of the next image. It is an inkjet recording device.

The invention according to claim 2 is the inkjet recording apparatus according to claim 1.
A collection flow path for returning ink from the recording head to the second tank is provided.
The difference between the upper limit storage amount and the standard storage amount is larger than the ink capacity of the ink flow path from being sent out from the second tank to returning to the second tank.

The invention according to claim 3 is the inkjet recording apparatus according to claim 1 or 2.
Equipped with a notification unit that performs a predetermined notification operation
When the reference sensor does not detect the standard amount of ink, the control unit operates the first liquid feeding means, and after operating the first liquid feeding means, the control unit operates the first liquid feeding means for a predetermined continuation reference time or more. When the reference sensor does not detect the standard amount of ink, the notification unit is made to perform a notification operation.

The invention according to claim 4 is the inkjet recording apparatus according to any one of claims 1 to 3.
The maximum ink feeding speed by the first liquid feeding means is higher than the ink feeding speed by the second liquid feeding means according to the maximum ink ejection amount from the recording head during the operation of the recording head. It is characterized by being large.

The invention according to claim 5 is the inkjet recording apparatus according to any one of claims 1 to 4.
A third tank is provided between the second liquid feeding means and the recording head.

The invention according to claim 6
A recording head that ejects ink and
The first tank to store ink and
A second tank for storing the ink supplied from the first tank, and
A first liquid feeding means for feeding ink from the first tank to the second tank, and
One or a plurality of second liquid feeding means for feeding ink from the second tank to the recording head, and
A reference sensor for determining whether or not a predetermined standard amount of ink is stored in the second tank, and
An upper limit sensor that determines whether or not an upper limit storage amount of ink larger than the standard storage amount is stored in the second tank, and an upper limit sensor.
A lower limit sensor for determining whether or not a lower limit storage amount of ink smaller than the standard storage amount is stored in the second tank, and a lower limit sensor.
Control unit and
A notification unit that performs a predetermined notification operation and
With
The control unit
Whether or not the first liquid feeding means operates is determined according to the detection result of the reference sensor.
Performs a predetermined abnormality response operation according to the detection results of the upper limit sensor and the lower limit sensor.
When the reference sensor does not detect the standard storage amount of ink, the first liquid feeding means is operated, and the operation of the first liquid feeding means until the reference sensor detects the standard storage amount again. counting the time, to set the continuous reference time Jo Tokoro based on one or more times of the counting results,
When the reference sensor does not detect the standard amount of ink, the first liquid feeding means is operated, and after the first liquid feeding means is operated, the reference sensor is said to have a predetermined continuation reference time or longer. when detecting no ink of the standard storage amount is Ru jet recording apparatus der characterized that you to perform a notification operation to the notification unit.

According to the present invention, there is an effect that ink can be supplied to the inkjet head while dealing with an abnormality in the amount of ink stored with more appropriate operation efficiency.

It is an overall perspective view which shows the inkjet recording apparatus of embodiment of this invention. It is a figure explaining the ink flow path of an inkjet recording apparatus. 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 ink supply control process. It is a flowchart which shows the modification of the ink supply control processing.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is an overall perspective view of the inkjet recording device 100 according to the embodiment 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 and a carriage elevating unit 23, and the combination of these carriages 22 and the carriage elevating unit 23 is provided in a number of sets (8 sets in this case) according to the number of ink colors. .. 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, recording heads), which are arranged in the upper direction (z direction) and can eject ink over the entire width of the conveyed recording medium, are fixed to form 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. 3) 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 ink storage unit 30 stores inks of each color used for forming an image 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 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 (first tank), a supply pump 32 (first liquid feeding means), 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 supply 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 (second tank). 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 (second liquid feeding means), a filter 254, a degassing module 255, and a liquid feeding common flow path. 256 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 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 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 (third tank), a common supply valve 263, and the like.
The maintenance flow path 265 is provided with a maintenance flow path flow valve 266.

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. An 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 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 storage amount of ink for determining whether or not ink is supplied from the main tank 31 to the sub tank 251 by the supply pump 32 (whether or not the supply pump 32 operates) 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. Therefore, if the ink is below the lower limit storage amount, it is an abnormal situation that the ink is not supplied. 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. Therefore, if the upper limit storage amount is exceeded, an abnormal situation such as excessive ink supply or mixing of something other than ink may occur. 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 usually 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. The measured value of the flow meter 252 is used here when the operation display unit 42 (see FIG. 3) displays the status and holds the history information, and is not used for abnormality detection or the like, but will be described later. It may be used for calculating the notification reference time of.

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 the predetermined number of inkjet heads 211 is divided into a plurality of blocks and separated from each other. Ink may be supplied from the sub tank 251 by the liquid feed pump 253 of the above. 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 feed pump 253 at the maximum ink liquid feed speed even in a situation where the largest amount of ink is ejected by the inkjet head 211 (during the formation of a solid image, etc.).

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 the leaked ink is not allowed to reach the vacuum pump 293, thereby preventing the vacuum pump 293 from failing or being damaged.

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 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 flow valve 261 and other valves whose open / closed state is controlled are not particularly limited, but here, a solenoid valve, for example, a plunger (movable iron piece) provided in the ink flow path is used as an electromagnetic force. A solenoid valve or the like that switches the opening and closing of the flow path by moving it by a spring force is used, and the opening / closing operation is performed according to the voltage applied by the control of the control unit 40 (see FIG. 3). In FIG. 2, the black-painted valve such as the intermediate tank flow valve 261 is a valve that is closed in a normal state (when the ground voltage is supplied or when the voltage is not supplied). The white valves such as the common supply valve 263 are valves that are open in the normal state.

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 (negative pressure), that is, a pressure lower than the atmospheric 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 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 naturally leaks 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. do not. 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 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 forming operation, if the amount of ink inside the intermediate tank 262 is within an appropriate range and it is not necessary to additionally supply ink to the intermediate tank 262 by the liquid feed pump 253, maintenance is performed. Both the flow path flow valve 266 and the intermediate tank flow valve 261 are closed.

The maintenance flow path 265 was pressurized and sent out to the liquid transfer common flow path 256 and the inkjet head 211 by the liquid transfer 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, by sending the pressurized ink by the liquid feeding pump 253 with the individual supply valve 258 opened and the recovery valve 273 closed, the pressurized ink is discharged from each nozzle of the inkjet head 211. Therefore, the air bubbles in the nozzle are discharged, and the cause of clogging of the nozzle opening or the like, for example, a solidified ink block is discharged to eliminate the clogging.

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 individual supply valve 258 switches whether or not ink can be supplied from the liquid feed common flow path 256 to the individual flow path 257 that branches from the liquid feed common flow path 256 and communicates with the plurality of inkjet heads 211. While all of these individual supply valves 258 are opened during normal image formation 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 a part of the inkjet heads 211 for inspection or cleaning of a part of the inkjet heads 211, the ink is provided in the individual flow path 257 communicating with the part of the inkjet heads 211. Only the individual supply valve 258 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.

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 (ink pressurization) status from the liquid feed pump 253. In this way, it is possible to suppress the spread of pressure fluctuations related to the operation of the other inkjet head 211 and the liquid feed pump 253, and apply pressure to the ink in the inkjet head 211 with an appropriate pressure pattern when the ink is ejected from the inkjet head 211. Then, the ink is ejected normally.

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 vibrating plate to change the pressure on the ink. It has a piezo-type configuration.

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. Prevent 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 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. 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. ..

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 a ejection failure 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 the ink sent out by the liquid feed pump 253 is simply circulated, 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. 3 is a block diagram showing a functional configuration of the inkjet recording device 100.
The inkjet recording device 100 includes the above-mentioned transfer motor 12, 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, and intermediate reference sensor 262b. , 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, Electromagnetic brake 233, and In addition to the elevating motor 232, a control unit 40, a communication unit 41, an operation display unit 42, a head drive unit 24, a motor driver 231 and a notification operation unit 43 (notification unit) are provided.

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 the program related to the ink supply control described above, and the initial setting data includes an initial value of the notification reference time (predetermined continuation reference time). This notification reference time is a reference time related to abnormality detection of the operation time (duration of liquid feeding operation) of the supply pump 32 when ink is supplied from the main tank 31 to the sub tank 251. That is, if the operation time of the supply pump 32 exceeds the notification reference time but the operation of the supply pump 32 is stopped, that is, if the standard amount of ink is not stored, the ink supply abnormality, mainly the main It is determined that the tank 31 is out of ink. The initial values of the notification reference time include the assumed maximum operating time, for example, the ink consumption rate (ink ejection amount per hour) at the time of forming the image that consumes the most ink (that is, a solid image) and the supply pump 32. Depending on the difference from the ink feeding rate due to the normal operation of the above, it is possible to set a time with some allowance for the time required for the standard amount of ink to be restored.

Further, the ROM 403 includes a non-volatile memory that can be overwritten and updated, and has a notification reference time 403b that holds the latest set value of the notification reference time whose settings are updated and maintained at any time, and transmission when the supply pump 32 operates. The supply time history data 403a, which is the history data of the duration of the liquid operation, that is, the ink supply time to the sub tank 251 is stored. As this historical data, it is possible to set so that only the data within the latest predetermined period or within a predetermined number of times (one or a plurality of times) is retained. The memory 404 includes a RAM for temporarily storing image data to be formed. In the actually formed image, the ink consumption rate is lower than the formation of the image that consumes the most ink as described above, and therefore, the liquid feeding operation by the supply pump 32 necessary for recovering the ink amount of the standard storage amount is performed. Since the duration is expected to be shorter, it is assumed that the ink will run out more appropriately and quickly by acquiring the measured value (counting result) of this duration while outputting the same image and setting and adjusting the notification reference time. In this case, it is possible to notify the abnormality. The specific adjustment method is not particularly limited, but for example, the maximum value, the maximum value, or the average value of the acquired latest measured values of a predetermined number of times multiplied by a predetermined coefficient is set last time. The weighted average of the notification reference time or the notification reference time divided by a predetermined coefficient and the latest average value or maximum value of several times, or the weighted average value multiplied by a predetermined coefficient, etc. Can be mentioned.
When the image to be formed is switched, each actually measured value of the stored supply time history data 403a may be deleted to return the notification reference time to the initial value.

The head drive unit 24 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 24 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 24 is generated according 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 24 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 formation 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, in the inkjet recording apparatus 100, the line sensor for detecting the image quality abnormality (defectiveness) of the image formed on the recording medium and the supplied recording medium are not normally placed on the transport surface. It may be provided with a reading unit such as a mounting abnormality detection sensor that detects.

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

Next, the ink supply control operation in the inkjet recording apparatus 100 of the present embodiment will be described.
The inkjet recording apparatus 100 controls the operation of the supply pump 32 only according to (depending on) whether or not the standard storage amount of ink is detected by the reference sensor 251a. On the other hand, based on the detection result of the lower limit sensor 251b, the ink supply abnormality from the main tank 31, that is, the ink out of the main tank 31 is mainly determined, the operation of the inkjet head 211 is determined, and the upper limit sensor is further determined. Ink inflow abnormality into the sub tank 251 is detected according to the detection result of 251c, and notification operation and operation control of each part are performed as an operation corresponding to each abnormality (abnormality response operation).

FIG. 4 is a flowchart showing a control procedure by the control unit 40 of the ink supply control process executed by the inkjet recording apparatus 100 of the present embodiment.
This ink supply control process is started when the operation of the inkjet recording device 100 is started, and is continuously executed until the operation is stopped due to normal or abnormal detection.

When the ink supply control process is started, the control unit 40 (CPU401) first turns off the detection result of the upper limit sensor 251c, that is, does not detect the upper limit storage amount of ink (ink storage amount of the sub tank 251). Is less than the upper limit storage amount) (step S101). When it is determined that the ink jet is not in the off state (“NO” in step S101), the ink storage amount is equal to or greater than the upper limit storage amount, so that the control unit 40 stops the operation of the inkjet head 211 and all the pumps. The display screen of the operation display unit 42 and the notification operation unit 43 are made to perform a predetermined notification operation (step S102). Then, the control unit 40 ends the ink supply control process.

When it is determined that the detection result of the upper limit sensor 251c is in the off state (“YES” in step S101), the control unit 40 has the detection result of the lower limit sensor 251b in the on state, that is, the ink of the lower limit storage amount. Is detected (the ink storage amount of the sub tank 251 is equal to or greater than the lower limit storage amount) (step S111). When it is determined that the ink jet head is not in the ON state (“NO” in step S111), the ink storage amount is less than the lower limit storage amount. Therefore, the control unit 40 prohibits the operation of the inkjet head 211 and performs an image forming operation. If it is inside, the operation of the inkjet head 211 is stopped. Further, the control unit 40 causes the display screen of the operation display unit 42 and the notification operation unit 43 to perform a predetermined notification operation (step S112). Then, the process of the control unit 40 shifts to step S122.
At this time, the control unit 40 may stop the operation of the supply pump 32. In this case, or if the operation of the supply pump 32 has already been stopped before the operation of step S112, the user replaces the main tank 31 and then performs a predetermined input operation to the operation display unit 42 to supply the supply pump. It is necessary to restart the operation of 32. If the operation of the inkjet head 211 is reset when the operation of the supply pump 32 is restarted, the user will also reissue the command related to image formation.

When it is determined that the detection result of the lower limit sensor 251b is in the ON state (“YES” in step S111), the control unit 40 determines that the detection result of the reference sensor is in the ON state, that is, the standard amount of ink is stored. Is detected (the ink storage amount of the sub tank 251 is equal to or higher than the standard storage amount) (step S121). If it is determined that it is not in the ON state (“NO” in step S121), the control unit 40 determines whether or not the supply pump 32 is in the liquid feeding operation (step S122). When it is determined that the liquid feeding operation is not in progress (“NO” in step S122), the control unit 40 starts the liquid feeding operation of the supply pump 32 and starts counting the liquid feeding operation time (step). S123). Then, the process of the control unit 40 returns to step S101.

When it is determined that the liquid feeding operation of the supply pump 32 is in progress (“YES” in step S122), the control unit 40 determines whether or not the counting liquid feeding operating time is within the notification reference time. Determine (step S124). If it is determined that the notification reference time is within (“YES” in step S124), the process of the control unit 40 returns to step S101. When it is determined that the notification reference time is not within the notification reference time, that is, the notification reference time has been exceeded (“NO” in step S124), the control unit 40 causes an ink supply abnormality or more directly, the main. The display screen of the operation display unit 42 and the notification operation unit 43 are made to perform the notification operation to the effect that the tank 31 should be replaced (step S125). Then, the process of the control unit 40 returns to step S101. At this time, in the inkjet recording device 100 of the present embodiment, the operation of the supply pump 32 is continued. Therefore, as soon as the main tank 31 is replaced, the ink supply is restarted, and the reference sensor 251a returns to the ON state when the ink amount returns to the standard storage amount. After the process of step S125, before the main tank 31 is replaced and the ink is not supplied to the sub tank 251 and the ink is branched to “NO” in the determination process of step S111, the supply pump 32 is operated at a predetermined upper limit time. It can also be configured to stop the operation. In this case, as described above, it is necessary for the user to restart the operation of the supply pump 32 by performing a predetermined input operation to the operation display unit 42.

If it is determined in the determination process of step S121 that the determination result of the reference sensor 251a is in the ON state (“YES” in step S121), the control unit 40 asks whether the supply pump 32 is in the liquid feeding operation. Whether or not it is determined (step S126). If it is determined that the liquid feeding operation is not in progress (“NO” in step S126), the process of the control unit 40 returns to step S101.

When it is determined that the supply pump 32 is in the liquid feeding operation (“YES” in step S126), the control unit 40 stops the liquid feeding operation of the supply pump 32 (step S127). The control unit 40 acquires the counted operation time of the supply pump, adds or updates it to the supply time history data 403a, and updates the notification reference time using the latest supply time history data 403a as necessary. It is set and stored as the notification reference time 403b (step S128). Then, the process of the control unit 40 returns to step S101.

[Modification example]
FIG. 5 is a flowchart showing a modified example of the ink supply control process.
When executing the flowchart of this modification, the lower limit storage amount detected by the lower limit sensor 251b is set to be slightly higher than in the above case. That is, since image formation can continue within a predetermined limit even after the lower limit storage amount is cut, the lower limit storage amount is set higher by the amount corresponding to the predetermined limit.

In the ink supply control process of this modification, the process of step S112 is divided into the processes of steps S112a to S112c with respect to the ink supply control process described above, and the processes of steps S123 to S125 are replaced with the processes of steps S123a to S125a. In addition, the processes of steps S131, S132, S141, S142, and S151 have been added. In addition, the order of some processes has been changed. Other processes are the same, and the same process contents are designated by the same reference numerals and detailed description thereof will be omitted.

In the ink supply control process of the modified example, if it is determined in the determination process of step S111 that the lower limit sensor is not in the ON state (“NO” in step S111), the control unit 40 performs an ink shortage notification operation. (Step S112a). At this time, the control unit determines whether or not the formation of the image being formed is completed, that is, whether or not the timing of image formation is good (step S112b).
The image in the process of being formed here means, for example, the entire formed image corresponding to the entire image forming range of the divided recording medium such as one sheet of paper, or the case where the same image is repeatedly formed a plurality of times. It corresponds to unit image data set for each formation range, such as a single image formation range, and may include a plurality of individual partial images or the same image pattern. That is, the lower limit storage amount is set to be equal to or larger than the maximum ink amount (that is, the ink amount required for a solid image) required for image formation of the maximum size (maximum range) that can be set by the inkjet recording apparatus 100 as this unit image data. ..

If it is determined that the formation of the image in the middle of formation has not been completed (in the middle of forming the image) (“NO” in step S112b), the process of the control unit 40 shifts to step S131. When it is determined that the image formation in the middle of formation is completed (the formation of the image is separated. After the formation of the image in the middle of formation and before the formation of the next image is started), it is determined (step S112b). (YES), the control unit 40 prohibits the subsequent operation of the inkjet head 211 and stops the operation of the inkjet head 211 during operation (step S112c). Then, the process of the control unit 40 shifts to step S131.

If it is determined in step S121 that the reference sensor is not in the ON state (“NO” in step S121), the process of the control unit 40 shifts to step S131.
When the process shifts to the process of step S131, the control unit 40 determines whether or not the elapsed time since the reference sensor is turned off is “0” (step S131). When it is determined that the elapsed time is "0"("YES" in step S131), the control unit 40 starts the operation of the supply pump 32, and the elapsed time and the liquid feeding operation time of the supply pump 32. Counting with (operating time) is started (step S132). Then, the process of the control unit 40 returns to step S101.

If it is determined that the elapsed time is not "0" ("NO" in step S131), the control unit 40 determines whether or not the elapsed time has reached the notification reference time (step S124a). The equal "=" here does not mean that they are exactly equal, but that the elapsed time is the first discrimination process after the notification reference time has elapsed. When it is determined that the notification reference time has been reached (“YES” in step S124a), the control unit 40 causes the display screen of the operation display unit 42 and the notification operation unit 43 to perform a notification operation for prompting the replacement of the main tank. At the same time, the operation of the supply pump 32 is stopped (step S125a). At this time, the counting of the liquid feeding operation time is stopped and the value is initialized. Then, the process of the control unit 40 returns to step S101.

When the elapsed time is not the timing when the notification reference time is reached, that is, the elapsed time is less than the notification reference time, or the notification reference time has already passed (it is determined that the notification reference time has already been reached). If it is determined (“NO” in step S124a), the control unit 40 determines whether or not the supply pump 32 is operating (step S122). If it is determined that the product is in operation (“YES” in step S122), the control unit 40 determines whether or not the liquid feeding operation time of the supply pump 32 is equal to or longer than the continuous upper limit time (step S141). .. This continuous upper limit time corresponds to the maximum estimated time at which the reference sensor 251a is assumed to be turned on by the operation of the supply pump 32 in each situation, or the time including a slight margin. That is, as the elapsed time becomes longer, the ink storage amount may be lower than the standard storage amount. Therefore, the continuous upper limit time is a variable that becomes longer according to the duration. The maximum estimated time is from the minimum ink storage amount assumed according to the elapsed time to the standard storage amount when the supply pump 32 is continuously operated at the time of forming an image that maximizes the ink consumption. Calculated as the time required to recover the amount.

If it is determined that the liquid feeding operation time is not equal to or longer than the continuous upper limit time (“NO” in step S141), the process of the control unit 40 returns to step S101. If it is determined that the continuation upper limit time or longer is exceeded (“YES” in step S141), the control unit 40 stops the operation of the supply pump 32 (step S142). Further, at this time, the control unit 40 stops counting the liquid feeding operation time and initializes the value of the liquid feeding operation time. Then, the process of the control unit 40 returns to step S101.

When it is determined in the determination process of step S122 that the supply pump 32 is not in operation (“NO” in step S122), the control unit 40 issues an operation restart command of the supply pump 32 to the operation display unit 42. It is determined whether or not it has been acquired based on the input operation or whether or not it is the operation restart timing of the supply pump 32 (step S151). Here, the operation restart command is received at any time by performing a predetermined operation on the operation display unit 42 when the user replaces the main tank 31. Further, as described above, when the operation of the supply pump 32 is stopped while the reference sensor 251a is off, the operation of the supply pump 32 is automatically restarted after a predetermined time has elapsed. .. This predetermined time may be a fixed time from the timing when the operation is stopped, or may be a fixed time from the timing when the previous operation is started or restarted. Alternatively, the predetermined time may be extended each time the operation start / restart and stop of the supply pump 32 are repeated.

If it is determined that the operation restart command has not been acquired and it is not the operation restart timing of the supply pump 32 (“NO” in step S151), the process of the control unit 40 returns to step S101. When the operation restart command is acquired or it is determined that it is the operation restart timing of the supply pump 32 (“YES” in step S151), the control unit 40 restarts the operation of the supply pump 32 and sends the feed. The counting of the liquid operating time is started again from "0" (step S123a). Then, the process of the control unit 40 returns to step S101.

If it is determined in step S121 that the reference sensor 251a is on (“YES” in step S121), the elapsed time counting is stopped and the value is initialized. Further, when the supply pump is stopped in the process of step S127, the counting of the liquid feeding operation time is stopped and the value is initialized.

As described above, the inkjet recording apparatus 100 of the present embodiment includes an inkjet head 211 for ejecting ink, a main tank 31 for storing ink, a sub tank 251 for storing ink supplied from the main tank 31, and a main tank. A predetermined standard storage amount of ink is stored in the supply pump 32 that feeds ink from 31 to the sub tank 251 and one or more liquid feed pumps 253 that feed ink from the sub tank to the inkjet head 211. A reference sensor 251a for determining whether or not the ink is stored, an upper limit sensor 251c for determining whether or not the sub tank has an upper limit storage amount of ink larger than the standard storage amount, and a lower limit storage amount smaller than the standard storage amount in the sub tank 251. A lower limit sensor 251b for determining whether or not ink is stored and a control unit 40 are provided, and the control unit 40 determines whether or not the supply pump 32 operates according to the detection result of the reference sensor 251a, and the upper limit sensor. A predetermined abnormality response operation is performed according to the detection results of the 251c and the lower limit sensor 251b.
As described above, in the inkjet recording apparatus 100, since the operation of the supply pump 32 is determined according to the detection of the reference sensor 251a for detecting the standard storage amount, the operation control can be easily performed without using a plurality of parameters. Further, it is not necessary to increase the number of sensors required for determining whether or not the supply pump 32 is operating more than necessary.
In addition, since the ink storage amount does not deviate significantly from the standard storage amount in normal times, the margin (volume difference) up to the upper and lower limit storage amounts set above and below the standard storage amount is large compared to the capacity of the sub tank. Easy to take. As a result, it is not necessary to immediately stop the operation of the inkjet head 211 when a slight abnormality occurs, particularly an ink supply abnormality due to the main tank 31 running out of ink, while inkjet recording such as an upper limit storage amount or more and a lower limit storage amount or less occurs. It is possible to reliably detect a level of ink storage that causes a problem in the operation of the device 100, and appropriately perform an abnormality response operation such as a notification operation or prohibition of operation of the inkjet head 211.
Therefore, in the inkjet recording device 100, ink can be supplied to the inkjet head while dealing with an abnormality in the amount of ink stored in the sub tank 251 with more appropriate operating efficiency.

Further, since the storage amount sensor does not have to be provided in the main tank 31, the configuration of the main tank 31 to be replaced becomes easy, and the main tank 31 can be easily attached / detached at the time of replacement. Similarly, since it is not necessary to integrate the flow rate from the main tank 31 to obtain the remaining amount of the main tank 31, the notification operation is performed at a more appropriate timing by suppressing the error of the remaining amount, and the inkjet head 211 Ink ejection operation can be prohibited.

Further, a collection flow path 27 for returning ink from the inkjet head to the sub tank 251 is provided, and the difference between the upper limit storage amount and the standard storage amount is based on the ink capacity of the ink flow path from the time when the ink is sent from the sub tank 251 to the time when the ink is returned to the sub tank 251. Is also big.
Therefore, in the inkjet recording device 100, it is possible to normally collect all the ink in the ink flow path (circulation flow path) to the sub tank 251 for maintenance or the like, and the sub tank is really due to an abnormality in the supply pump 32 or the sub tank 251. It is possible to appropriately determine an abnormal situation such as the possibility of overflowing 251. In addition, normally, it is not expected that the ink storage amount will increase significantly more than before and after the standard storage amount only with the reference sensor 251a. Therefore, even if the ink in the ink flow path is expected to be recovered, the capacity margin of the sub tank 251 is larger than necessary. It can be made into an appropriate size without taking it.

Further, a notification operation unit 43 that performs a predetermined notification operation is provided, and the control unit 40 operates the supply pump 32 when the reference sensor 251a does not detect the ink of the standard storage amount, and then operates the supply pump 32. When the reference sensor 251a does not detect the standard amount of ink for the predetermined continuation reference time or longer, the notification operation unit 43 is made to perform the notification operation.
That is, when the ink storage amount of the sub tank 251 does not recover as expected, an ink supply abnormality, mainly the ink of the main tank 31, has run out, and this can be easily and quickly detected by detecting only the reference sensor 251a. However, it is possible to notify the user and urge the replacement of the main tank 31 or the like. Further, at this time, since the range of the normal ink storage amount is narrow, the width from the detection of the abnormality to the lower limit storage amount in which it becomes difficult to actually supply the normal ink to the inkjet head 211 is set to the sub tank 251. Since it can be set wider than the size of the ink jet, it is possible to encourage the user to replace the main tank 31 with more margin.

Further, when the lower limit sensor 251b does not detect the ink of the lower limit storage amount, the control unit 40 prohibits ink ejection from the inkjet head 211 as an abnormality response operation. That is, since it is possible to provide a grace period from the detection of the ink supply abnormality by the reference sensor 251a until the ink ejection operation by the inkjet head 211 actually needs to be prohibited, the image is formed even when the ink in the main tank 31 is exhausted. The user can replace the main tank 31 with a margin without interrupting the operation to restart and continue the ink supply.

Further, the lower limit storage amount is set to be equal to or larger than the maximum ink amount required for forming an image in the maximum range that can be set as an image formed by the inkjet head 211, and the lower limit sensor 251b of the control unit 40 is set to the lower limit storage amount. Ink ejection from the inkjet head 211 is prohibited after the image being formed is formed at the timing when the ink is no longer detected and before the formation of the next image is started. That is, in the case of running out of ink in the main tank 31, it is possible to prompt the user in advance to replace the main tank 31 before the ink jet head 211 is actually unable to supply ink normally, and further, the main tank 31 can be replaced. Even if the ink storage amount of the sub tank 251 falls below the lower limit storage amount without being replaced, the ink ejection is stopped after the formation of the image that was being formed at that time is completed, so that the operation is stopped during the image formation. Do not waste the recorded recording medium and ink.

Further, the maximum ink liquid feeding speed by the supply pump 32 is larger than the ink liquid feeding speed by the liquid feeding pump 253 according to the maximum ink ejection amount from the inkjet head 211 during the operation of the inkjet head 211. Therefore, even when the image forming operation is executed at the maximum capacity of the inkjet head 211, when the ink is supplied from the normal main tank 31 to the sub tank 251 or the ink is supplied to the sub tank 251 after the main tank 31 is replaced. , The amount of ink in the sub tank 251 can be reliably restored to the standard storage amount.

An intermediate tank 262 is provided between the liquid feed pump 253 and the inkjet head 211. Therefore, the ink pressurized and sent out from the sub tank 251 by the liquid feed pump 253 can be easily and appropriately supplied to the inkjet head 211 by pressure control regardless of the amount of ink stored in the sub tank 251. be.

Further, the control unit 40 operates the supply pump 32 when the reference sensor 251a does not detect the standard storage amount of ink, and counts the operating time of the supply pump 32 until the reference sensor detects the standard storage amount again. A continuation reference time for detecting a supply abnormality from the main tank 31 to the sub tank 251 is set based on the result of one or a plurality of times of the counting.
That is, it is most certain that the initial value is set to the maximum time corresponding to the case where the ink ejection amount by the inkjet head 211 becomes maximum as the continuation reference time, but the ink ejection depends on the actual formation target image. Since the amounts are different, by setting a shorter continuation reference time based on the actually measured values corresponding to the different ink ejection amounts, it is possible to detect the ink supply abnormality more quickly and surely and notify the user.

The present invention is not limited to the above embodiment, and various modifications can be made.
For example, in the above-described embodiment, as an abnormality response operation, a predetermined notification operation that can be executed by the display screen of the operation display unit 42 or the notification operation unit 43 is performed, the operation of each part of the inkjet recording device 100, or the inkjet head. Although it was decided to prohibit the operation of 211, various other operations such as transmission of an e-mail or a message via the communication unit 41 are possible.

Further, in the above embodiment, the upper limit storage amount corresponding to 251c is set to a level that is not detected even if all the ink in the ink flow path (circulation flow path) is returned to the upper limit sensor, but the upper limit storage amount is such a case. May be at a detected level. However, the capacity of the sub tank 251 is preferably larger than the sum of the standard storage capacity and the ink capacity.

Further, in the above embodiment, the presence / absence of operation of the supply pump 32 is determined in real time based on the detection result in real time by the reference sensor 251a, but the detection data is acquired at a predetermined detection interval and the detection interval is adjusted. The operation or non-operation of the supply pump 32 may be switched in time steps. Alternatively, although the detection result itself is acquired in real time, it may be set to operate continuously for a predetermined time after the operation / non-operation of the supply pump 32 is once switched. These detection intervals and predetermined times are sufficiently longer than the time required for the ink storage amount to change from the standard storage amount to the lower limit storage amount or the upper limit storage amount due to the liquid transfer by the liquid transfer pump 253 or the ink supply by the supply pump 32. Short to.

Further, in the above embodiment, the case where the initial value (fixed value) according to the assumed maximum time and the updated value based on the measured time are used as the predetermined continuation reference time has been described, but it is linked to the operating state of the liquid feed pump 253. You may change it.

Further, in the above embodiment, when the ink storage amount falls below the lower limit storage amount, the operation of the inkjet head 211 is immediately prohibited (stopped), and the operation is prohibited after the image is formed to a good point. In the case where the operation is prohibited immediately, the image formation is performed from the position where the image formation is stopped after the ink supply is restarted from the main tank 31 and the operation prohibition is released. May be restarted to complete the formation of the image to be formed.

Further, in the above embodiment, the back pressure control in the nozzle of the inkjet head 211 is performed by using the intermediate tank 262, but the back pressure control is not limited to this method.
Further, in the above embodiment, the ink flow path has been described as a circulation flow path, but the present invention can be applied even when there is no recovery flow path for returning to the sub tank 251.

Further, in the above-described embodiment, the main tank 31 is replaced together with the container, but the ink may be replenished by injecting ink into the container of the main tank 31.

Further, in the above embodiment, the supply pump 32 is used as the first liquid feeding means for supplying ink from the main tank 31 to the sub tank 251, but the present invention is not limited to this. As a relative arrangement that allows the ink in the main tank 31 to flow into the sub tank 251 by gravity, the ink supply availability to the sub tank 251 is switched by controlling the opening and closing of the ink supply valve provided in the ink flow path. You may.

Further, in the above embodiment, the capacity of the sub tank 251 is described as being smaller than the capacity of the main tank 31, but the present invention is not limited to this. The capacity of the sub tank 251 may be larger than that of the main tank 31, and the possible time for image formation after the empty detection of the main tank 31 can be set longer, so that the main tank 31 can be replaced or replenished with more margin. It becomes possible to do it.

Further, in the above embodiment, an inkjet recording device provided with a line head for ejecting inks of a plurality of colors has been described as an example, but only image formation in a single color may be used, and this is colorless. Also included is an inkjet recording device that coats the recording medium with the ink of. Further, the number and arrangement of nozzles in the inkjet head 211 and the number and arrangement of a plurality of inkjet heads 211 are arbitrary, and an image is formed on the recording medium while moving (scanning) the inkjet head 211 with respect to the recording medium. The present invention can also be applied to a scanning type inkjet recording device or the like.
In addition, specific details such as the configuration, arrangement, and control contents shown in the above-described embodiment can be appropriately changed without departing from the spirit of the present invention.

The present invention can be applied to an inkjet recording device.

100 Inkjet recording device 10 Conveyor 11 Drive roller 12 Conveyor motor 14 Convey belt 20 Image forming part 211 Inkjet head 22 Carriage 23 Carriage elevating part 231 Motor driver 232 Elevating motor 233 Electromagnetic brake 234 Valve member 235 Support part 24 Head drive part 251 Sub tank 251a Reference sensor 251b Lower limit sensor 251c Upper limit sensor 252 Flow meter 253 Liquid feed pump 254 Filter 255 Degassing module 256 Liquid feed common flow path 257 Individual flow path 258 Individual supply valve 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 valve 291 Check valve 292 Chamber 292a Liquid level sensor 293 Vacuum pump 294 Pressure sensor 30 Ink storage section 31 Main tank 32 Supply pump 35 Rack 40 Control section 401 CPU
402 RAM
403 ROM
403a Supply time history data 403b Notification reference time 404 Memory 41 Communication unit 42 Operation display unit 43 Notification operation unit 49 Bus

Claims (6)

A recording head that ejects ink and
The first tank to store ink and
A second tank for storing the ink supplied from the first tank, and
A first liquid feeding means for feeding ink from the first tank to the second tank, and
One or a plurality of second liquid feeding means for feeding ink from the second tank to the recording head, and
A reference sensor for determining whether or not a predetermined standard amount of ink is stored in the second tank, and
An upper limit sensor that determines whether or not an upper limit storage amount of ink larger than the standard storage amount is stored in the second tank, and an upper limit sensor.
A lower limit sensor for determining whether or not a lower limit storage amount of ink smaller than the standard storage amount is stored in the second tank, and a lower limit sensor.
Control unit and
With
The lower limit storage amount is set to be equal to or larger than the maximum amount of ink required for forming an image in the maximum range that can be set as an image formed by the recording head.
The control unit
Whether or not the first liquid feeding means operates is determined according to the detection result of the reference sensor.
There rows predetermined anomaly operation corresponding to the upper sensor and the lower limit sensor detection result,
It is characterized in that ink ejection from the recording head is prohibited after forming an image in the process of formation at a timing when the lower limit sensor no longer detects the ink of the lower limit storage amount and before starting formation of the next image. Inkjet recording device. A collection flow path for returning ink from the recording head to the second tank is provided.
The first aspect of claim 1, wherein the difference between the upper limit storage amount and the standard storage amount is larger than the ink capacity of the ink flow path from the time when the ink is sent from the second tank to the time when the ink flow path returns to the second tank. Inkjet recording device. Equipped with a notification unit that performs a predetermined notification operation
When the reference sensor does not detect the standard amount of ink, the control unit operates the first liquid feeding means, and after operating the first liquid feeding means, the control unit operates the first liquid feeding means for a predetermined continuation reference time or more. The inkjet recording apparatus according to claim 1 or 2, wherein when the reference sensor does not detect the standard amount of ink, the notification unit is made to perform a notification operation. The maximum ink feeding speed by the first liquid feeding means is higher than the ink feeding speed by the second liquid feeding means according to the maximum ink ejection amount from the recording head during the operation of the recording head. The inkjet recording apparatus according to any one of claims 1 to 3, wherein the ink jet recording apparatus is large. The inkjet recording apparatus according to any one of claims 1 to 4 , wherein a third tank is provided between the second liquid feeding means and the recording head. A recording head that ejects ink and
The first tank to store ink and
A second tank for storing the ink supplied from the first tank, and
A first liquid feeding means for feeding ink from the first tank to the second tank, and
One or a plurality of second liquid feeding means for feeding ink from the second tank to the recording head, and
A reference sensor for determining whether or not a predetermined standard amount of ink is stored in the second tank, and
An upper limit sensor that determines whether or not an upper limit storage amount of ink larger than the standard storage amount is stored in the second tank, and an upper limit sensor.
A lower limit sensor for determining whether or not a lower limit storage amount of ink smaller than the standard storage amount is stored in the second tank, and a lower limit sensor.
Control unit and
A notification unit that performs a predetermined notification operation and
With
The control unit
Whether or not the first liquid feeding means operates is determined according to the detection result of the reference sensor.
Performs a predetermined abnormality response operation according to the detection results of the upper limit sensor and the lower limit sensor.
When the reference sensor does not detect the standard storage amount of ink, the first liquid feeding means is operated, and the operation of the first liquid feeding means until the reference sensor detects the standard storage amount again. counting the time, to set the continuous reference time Jo Tokoro based on one or more times of the counting results,
When the reference sensor does not detect the standard amount of ink, the first liquid feeding means is operated, and after the first liquid feeding means is operated, the reference sensor is said to have a predetermined continuation reference time or longer. when detecting no ink of the standard storage amount, it <br/> be characterized and to Louis inkjet recording apparatus to perform a notification operation to the notification unit.

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