EP3446878A1

EP3446878A1 - Droplet ejecting device and method for maintaining droplet ejecting device

Info

Publication number: EP3446878A1
Application number: EP17785705.9A
Authority: EP
Inventors: Hiroshi Akita; Taku Mitsuhashi
Original assignee: Konica Minolta Inc
Current assignee: Konica Minolta Inc
Priority date: 2016-04-18
Filing date: 2017-03-15
Publication date: 2019-02-27
Anticipated expiration: 2037-03-15
Also published as: EP3446878A4; JP6950682B2; EP3446878B1; JPWO2017183363A1; WO2017183363A1

Abstract

Provided are a droplet ejecting device and a maintenance method therefor, with which pressurized maintenance is selectively performed on some ejection heads while the meniscus surface of ink is appropriately maintained in an easy and simple manner. This inkjet recording device is provided with: a plurality of inkjet heads (211); a liquid-feeding shared flow channel (256) and individual flow channels (257) for guiding ink into each of the inkjet heads (211); individual supply valves (258) for switching the respective individual flow channels (257) between open and closed states; a liquid-feeding pump (253) for pressure-feeding ink to the inkjet heads (211); and a control unit (40) for opening some of the individual supply valves (258) and pressure-feeding ink into the inkjet heads (211) that correspond thereto, and subsequently opening all of the individual supply valves (258) and pressure-feeding ink into all of the inkjet heads (211).

Description

Technological Field

The present invention relates to a droplet ejecting device and a method for maintaining the droplet ejecting device.

Background Art

There is a droplet ejecting device (inkjet recording device) which ejects droplets such as ink from a nozzle to record an image or form film or structures. Such droplet ejecting device needs to normally eject droplets from the nozzle. Therefore, conventionally, maintenance techniques are developed to perform inspection of whether the droplets (ink) are ejected normally using various methods or to solve abnormalities when they occur.
As a method to solve the abnormality, there is a technique to flow ink with a stronger pressure than normal in the ink flow path of the inkjet recording device to press and flow clogging. Specifically, when abnormalities occur in some recording heads (ejecting head), a flow of ink (liquid to be ejected) is selectively generated in the some recording heads to solve clogging more efficiently (for example, patent document 1).

Prior Art Document

Patent Document

Patent Document 1: Japanese Patent Application Laid-Open Publication No. 2012-000883

Summary

Problems to be Solved by the Invention

However, when pressured liquid is selectively sent to some of the ejecting heads, the flow path to the other ejecting heads is temporarily closed using an electromagnetic valve so that the liquid is not sent to the other ejecting heads. However, a movable component (movable iron piece) which closes or opens the flow path according to the switching between open and close usually moves swiftly in the electromagnetic valve. Therefore, due to such opening/closing movement, a pressure wave occurs in the liquid or a shock according to the movement of the movable component is transmitted to the ejecting head and drastic movement occurs in the liquid in the ejecting head. With this, the meniscus surface at the tip of the liquid in the ejecting head is destroyed.
A purpose of the present invention is to provide a droplet ejecting device and a method for maintaining the droplet device in order to suitably maintain the meniscus surface of the liquid to be ejected easily and simply while performing pressuring maintenance selectively on some of the ejecting heads.

Means for Solving the Problem

To achieve at least one of the abovementioned objects, according to an aspect of the present invention, there is a droplet ejecting device including: a plurality of ejecting heads including a nozzle which ejects droplets; a liquid flow path which introduces to each of the plurality of ejecting heads liquid which is to be ejected; an individual opening/closing unit which switches a communicating state and a non-communicating state between the liquid flow path and the plurality of ejecting heads for each of at least two or more groups; a liquid sending unit which pressures and sends the liquid into the ejecting head through the liquid flow path; and a pressuring controller which, after pressuring and sending liquid into some of the ejecting heads corresponding to the some of the individual opening/closing units in a state in which the some of the individual opening/closing units are open, opens all of the individual opening/closing units and pressures and sends the liquid to all of the ejecting heads.
In aspect 2, the droplet ejecting device according to aspect 1, wherein, the liquid flow path includes, an intermediate flow path which flows the liquid through an intermediate storage and a detouring flow path which is provided parallel with the intermediate flow path and which does not pass the liquid through the intermediate storage; the intermediate flow path is provided with an intermediate storage opening/closing unit which switches whether the liquid can flow into or out of the intermediate storage; the detouring flow path is provided with a detouring flow path opening/closing unit which opens and closes the detouring flow path; and the pressuring controller closes the intermediate storage opening/closing unit and opens the detouring flow path opening/closing unit when the liquid is pressured and sent in the state in which the some of the individual opening/closing units are open.
In aspect 3, the droplet ejecting device according to aspect 2, further including a pressure reducing unit which reduces pressure of the liquid in the liquid flow path, wherein, after pressuring and sending the liquid to the some of the ejecting heads, before opening all of the individual opening/closing units, the pressuring controller controls the pressure reducing unit to reduce the pressure of the liquid in the liquid flow path and opens the intermediate storage opening/closing unit.
In aspect 4, the droplet ejecting device according to aspect 3, wherein the pressure reducing unit includes a drawing unit which draws in liquid of the liquid flow path.
In aspect 5, the droplet ejecting device according to aspect 4, wherein after the intermediate storage opening/closing unit is opened, the pressuring controller controls the drawing unit to draw in the liquid of the liquid flow path and the intermediate storage to set the pressure of the liquid in the intermediate storage to a predetermined set value.
In aspect 6, the droplet ejecting device according to aspect 4 or 5, further including: a storage which stores liquid which the liquid sending unit pressures and sends to the ejecting head; and a collecting flow path which returns the liquid drawn in by the drawing unit to the storage.
In aspect 7, the droplet ejecting device according to any one of aspects 1 to 6, further including a pressuring supplying controller which pressures and supplies the liquid to each group of ejecting heads, the ejecting heads divided into groups of a predetermined maximum supply number or less.
In aspect 8, the method for maintaining a droplet ejecting device, the droplet ejecting device including, a plurality of ejecting heads including a nozzle which ejects droplets; a liquid flow path which introduces to each of the plurality of ejecting heads liquid which is to be ejected; an individual opening/closing unit which switches a communicating state and a non-communicating state between the liquid flow path and the plurality of ejecting heads for each of at least two or more groups; and a liquid sending unit which pressures and sends liquid into the ejecting head through the liquid flow path, the method including: controlling pressuring, after pressuring and sending liquid into some of the ejecting heads corresponding to the some of the individual opening/closing units in a state in which the some of the individual opening/closing units are open, to open all of the individual opening/closing units and to pressure and send the liquid to all of the ejecting heads.

Advantageous Effects of Invention

According to the present invention, it is possible to provide a droplet ejecting device which is able to suitably maintain the meniscus surface of the liquid to be ejected easily and simply while performing pressuring maintenance selectively on some of the ejecting heads.

Brief Description of the Drawings

FIG. 1 is an entire perspective view showing an inkjet recording device according to an embodiment of the present invention.
FIG. 2 is a diagram which describes an ink flow path of an inkjet recording device.
FIG. 3 is a diagram showing an example of a cross-sectional configuration of an individual supplying valve.
FIG. 4 is a block diagram showing a functional configuration of an inkjet recording device.
FIG. 5 is a flowchart showing a control process of a pressuring maintenance process performed in an inkjet recording device according to the present embodiment.

Embodiment for Carrying Out the Invention

An embodiment of the present invention is described with reference to the diagrams.
FIG. 1 is an entire perspective view of the inkjet recording device 100 according to an embodiment of the droplet ejecting device of the present invention.
The inkjet recording device 100 is a device employing a one pass method including a plurality of line heads and is provided with a conveying unit 10, an image forming unit 20, and an ink storage unit 30.
The conveying unit 10 includes a driving roller 11, a conveying motor 12, and a conveying belt 14. The conveying motor 12 rotates the driving roller 11 at a predetermined speed. A driven roller (not shown) and an endless conveying belt 14 are rolled around the driving roller 11. The conveying belt 14 moves due to the rotation of the driving roller 11. An outer side surface of the conveying belt 14 functions as the conveying surface and the recording medium is placed on the conveying surface. The recording medium is conveyed in a conveying direction due to the circling movement of the conveying belt 14.
The image forming unit 20 includes a carriage 22, a carriage raising/lowering unit 23, and a reader 24. Such combination of the carriage 22 and the carriage raising/lowering unit 23 is provided in a number of pairs according to the number of colors of ink (here, 8 pairs). The carriage 22 each extend in a direction intersecting with the conveying direction (x-direction) of the recording medium by the conveying unit 10, here the width direction (y-direction) orthogonal to the x-direction. The carriage 22 is positioned above (z-direction) the conveying surface of the recording medium by the conveying unit 10. The structure is a line head structure in which a plurality of inkjet heads 211 (see FIG. 2, ejecting head) are fixed to be able to eject droplets of the ink (liquid to be ejected) throughout the entire width of the conveyed recording medium. The plurality of carriages 22 are provided in different positions in the conveying direction. The carriage 22 is provided so as to be able to change the distance above from the conveying surface with the carriage raising/lowering unit 23. The distance of the inkjet head 211 from the conveying surface changes together with the movement of the carriage 22.
The carriage raising/lowering unit 23 changes the distance from the conveying surface of the carriage 22. The carriage raising/lowering unit 23 includes a raising/lowering motor 232, an electromagnetic brake 233, a beam member 234, and a supporting unit 235.
Two beam members 234 are provided substantially parallel in a direction (here, orthogonal direction, that is, width direction) intersecting with the conveying direction above the conveying belt 14 (conveying surface side of recording medium). The supporting unit 235 is fixed in each edge of the beam members 234. The raising/lowering motor 232, the electromagnetic brake 233, and the carriage 22 are attached to the supporting unit 235.
The carriage 22 is raised or lowered and the position is determined according to the operation of the raising/lowering motor 232 and the electromagnetic brake 233 driven based on the control signal from the controller 40 (see FIG. 4).
The raising/lowering motor 232 moves the carriage 22 at a predetermined raising/lowering speed. For example, a servomotor or a stepping motor is used as the raising/lowering motor 232.
The electromagnetic brake 233 maintains a fixed state of the carriage 22, and when the fixed state is released in response to a driving signal, the movement of the carriage 22 by the raising/lowering motor 232 is temporarily possible. That is, in a normal state including when the power is cut off, the electromagnetic brake 233 fixes the carriage 22. As the electromagnetic brake 233, for example, a disk brake is used.
A reader 24 reads the image recorded on the recording medium. The reader 24 includes a line sensor including imaging elements aligned to be able to image the surface of the recording medium throughout a recordable width of the recording medium. Well-known line sensors such as a CCD sensor and a CMOS sensor are used as the line sensor. The recording medium is conveyed in the conveying direction while the line sensor sequentially images the recording medium in the width direction. With this, the recording medium can be imaged two-dimensionally, and the imaged data is sequentially sent to the controller 40 to be used in inspection of the recorded image.
The ink storage unit 30 stores ink in each color used in recording the image and supplies the ink to the inkjet head 211. The components of the ink storage unit 30, here, are positioned in a dedicated rack 35, and are connected to the image forming unit 20 through piping such as tubes.
Next, the configuration regarding an ink flow path (liquid flow path) from the ink storage unit 30 to the image forming unit 20 in the inkjet recording device 100 according to the present embodiment is described.
FIG. 2 is a diagram describing a configuration of an ink flow path in the inkjet recording device 100 according to the present embodiment.
The ink storage unit 30 includes a main tank 31 and a supplying pump 32.
The main tank 31 is provided for each ink color, and is arrayed in the rack 35. The ink of the main tank 31 is sent to the image forming unit 20 by the supplying pump 32. The entire main tank 31 can be exchanged, and the main tank 31 is formed to be detachable from the ink flow path leading to the supplying pump 32 regardless of the operation state of the supplying pump 32. That is, the main tank 31 can be attached while the supplying pump 32 is in a state of operation, and therefore, the ink can be immediately sent to the image forming unit 20 again.
The supplying pump 32 is not limited, and 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 supplying pump 32 is stored in a sub-tank 251 (storage unit). For such sub-tank 251, after the ink sent out from the sub-tank 251 reaches the inkjet head 211, the ink flow path returning to the sub-tank 251 again is provided (circulating flow path).
A flowmeter 252, a liquid sending pump 253 (liquid sending unit), a filter 254, a deaerating module 255, and a liquid sending common flow path 256 (common flow path) are provided from the sub-tank 251 to the inkjet head 211 (liquid sending flow path). A plurality of individual flow paths 257 are divided from the liquid sending common flow path 256. The ink passes through the individual supplying valve 258 (individual opening/closing unit) and the damper 259 to be sent to the inkjet head 211. The dampers 259 are connected to the inkjet head 211 in pairs.
Between the deaerating module 255 and the liquid sending common flow path 256, the ink flow path is divided between an intermediate tank flow path 260 (intermediate flow path) and a maintenance flow path 265 (detouring flow path). The intermediate tank flow path 260 is provided with an intermediate tank distributing valve 261, an intermediate tank 262 (intermediate storage), and a common supplying valve 263.
The intermediate tank distributing valve 261 and the common supplying valve 263 compose an intermediate storage opening/closing unit.
The maintenance flow path 265 is provided with a maintenance flow path distributing valve 266 (detouring flow path opening/closing unit).
In a collecting flow path 27 from a collection opening (outlet) of the inkjet head 211 to the sub-tank 251, first, after the flow paths of the ink discharged from two inkjet heads 211 divided in the damper 259 are joined, the joined flow path passes the check valve 271 to be joined with the collecting common flow path 272. Then, from the collecting common flow path 272, the ink flows through the collecting valve 273 and the circulating valve 274 so that the ink returns to the sub-tank 251. The collecting pump 275 is provided parallel with the circulating valve 274.
An edge of the liquid sending common flow path 256 opposite to the ink inflow side is connected directly to the downstream side of the collecting valve 273 through the bypass valve 270.
A release flow path which returns the ink to the sub-tank 251 is provided in between the liquid sending pump 253 and the filter 254, on the downstream side than the maintenance flow path distributing valve 266 of the maintenance flow path 265, and on the downstream side than an intermediate tank distributing valve 261 of the intermediate tank flow path 260, the ink passing through the check valves 281, 282, and 283, respectively. When ink sent out from the sub-tank 251 by the liquid sending pump 253 cannot flow to the inkjet head 211 due to problems in the filter 254, the deaerating module 255, the intermediate tank 262, or the liquid sending common flow path 256, or when the ink cannot flow and the ink accumulating midway of the liquid sending flow path increases resulting in increase of the ink pressure, if the ink pressure exceeds a predetermined pressure threshold, the check valves 281 to 283 as the relief valves are opened to return the ink to the sub-tank 251.
Although not limited, the capacity of the sub-tank 251 here is smaller than the capacity of the main tank 31. In order to detect the ink storage amount, the sub-tank 251 is provided with a reference sensor 251a, a lower limit sensor 251b, and an upper limit sensor 251c. The reference sensor 251a detects whether a standard storage amount of ink is stored to determine whether to supply ink from the main tank 31 to the sub-tank 251 with the supplying pump 32. That is, when the ink storage amount is smaller than the standard storage amount, the supplying pump 32 is operated and when the ink storage amount is larger than the standard storage amount, the supplying pump 32 is stopped.
The lower limit sensor 251b detects whether a lower limit storage amount of ink is stored to determine whether to prohibit operation of the inkjet head 211. 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 (ink ejection) of the inkjet head 211 is prohibited. When the ink is suitably supplied from the main tank 31 to the sub-tank 251, the ink amount of the sub-tank 251 does not decrease greatly from the standard storage amount. Therefore, when the amount of ink is smaller than the lower limit storage amount, this means that there is an abnormality such as there is no ink supply.
The upper limit sensor 251c detects whether ink is stored in the amount of an upper limit storage amount which shows danger of the sub-tank 251 overflowing. The upper limit storage amount is set to be larger than the total of the standard storage amount and the ink capacity of the entire circulating flow path (liquid sending flow path, inkjet head 211 and collecting flow path 27). That is, even if the ink is not ejected from the nozzle of the inkjet head 211 at all and all of the ink is returned to the sub-tank 251, the amount of ink still does not exceed the upper limit storage amount. Therefore, when the amount of ink is larger than the upper limit storage amount, this shows an abnormality such as excess ink supply or something other than ink is mixed.
In the inkjet recording device 100 according to the present embodiment, the sub-tank 251 is exposed to the atmosphere and the pressure on the ink is normally maintained to atmospheric pressure.
The flowmeter 252 detects and outputs the amount of liquid sent from the sub-tank 251 to the inkjet head 211 side by the liquid sending pump 253. The value measured by the flowmeter 252 here is used for displaying the status on the operation/display unit 42 (see FIG. 4) and holding history information, and is not used for detecting abnormalities, but the value can be used for detecting abnormalities in sending liquid.
The liquid sending pump 253 sends the ink inside the sub-tank 251 at a predetermined liquid sending speed (amount of liquid sent for a unit of time) to the filter 254 and its downstream side, that is, the side of the inkjet head 211 (liquid sending flow path). One liquid sending pump 253 is provided for the sub-tank 251 and this supplies ink to all of the inkjet heads 211. Alternatively, the inkjet heads 211 can be divided into a plurality of blocks including a predetermined number of inkjet heads 211 and a separate liquid sending pump 253 can be provided for each block to supply the ink from the sub-tank 251. The liquid sending abilities of the liquid sending pump 253 is to be able to sufficiently supply the maximum ink ejecting amount ejected by the inkjet head 211 for each unit of time when the image is formed. The liquid sending speed of the ink according to such maximum ink ejecting amount is slower than the maximum liquid sending speed of the ink of the supplying pump 32. Therefore, the liquid sending abilities of the liquid sending pump 253 does not have to be as good as the supplying pump 32, but a pump which is equal to the supplying pump 32, that is, the same type can be used. In this case, even if the maximum amount of ink is ejected from the inkjet head 211 (a solid image is formed, for example), the liquid sending pump 253 does not have to operate at the maximum liquid sending speed of the ink.
The liquid sending pump 253 is able to apply pressure and send ink to the inkjet head 211 equal to or more than the ink ejecting abilities. That is, the ink in the liquid sending common flow path 256, the individual flow path 257 and the inkjet head 211 which are where the ink is sent is in a state temporarily higher than atmospheric pressure.
The filter 254 removes foreign matter and impurities such as debris and dust or large bubbles in the ink. As described above, the sub-tank 251 is exposed to the atmosphere and the foreign matter, impurities, and bubbles may be mixed. Therefore, the filter 254 prevents the above from being sent to the inkjet head 211.
The deaerating module 255 removes air (gas) included in the ink. For example, the deaerating module 255 places the ink in contact with a vacuum region through a deaerating film and the air in the ink can be selectively absorbed in the vacuum region side. As the deaerating film, in order to effectively increase the area in contact with the ink and to more evenly come into contact with the ink, for example, a structure with a large number of microscopic threads with a vacuum state inside can be employed.
Here, the vacuum pump 293 absorbs the air on the vacuum region side of the deaerating module 255. The vacuum region here does not have to be an ultra-high vacuum state and a predetermined pressure sufficiently lower than the atmospheric pressure is set in advance. The pressure sensor 294 measures the 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 deaerating module 255 is connected to the chamber 292 through the check valve 291. The slight amount of ink which may pass the deaerating film or the ink which may leak to the vacuum region side at once when the deaerating film breaks flows to the bottom of the chamber 292 and is stored. The ink which gathers at the bottom of the chamber 292 is detected by a liquid amount sensor 292a to determine whether there is an abnormal amount of the leak of ink. When an abnormality is detected, the operation of the vacuum pump 293 and each unit is stopped, and the vacuum region is in communication with the atmosphere. As described above, the chamber 292 is used as a trap for the leaked ink, and this prevents the leaked ink from reaching the vacuum pump 293. As a result, this prevents the vacuum pump 293 from malfunctioning or being damaged.
Other than a device which directly measures the liquid amount, the following can be used as the liquid amount sensor 292a, a device which measures the change in the weight of the chamber 292 or a device which optically, electrically, or magnetically measures the signal output in response to the deforming from a member which changes in response to the change in weight, for example, the actuator which deforms by the load according to the weight of the chamber 292.
An absorbing unit 29 including the chamber 292, liquid amount sensor 292a, pressure sensor 294, and vacuum pump 293 is provided commonly in the deaerating module 255 in the circulating flow path provided for each ink color and the flow is joined downstream of the check valve 291 (chamber 292 side). That is, when an ink with a certain color leaks from the deaerating module 255, the check valve 291 prevents the ink with the certain color from flowing into the vacuum region side of the deaerating module 255 in the circulating flow path of the ink with another color.
The individual supplying valve 258 switches whether ink is supplied from the liquid sending common flow path 256 to the individual flow path 257 which communicates with the predetermined number (here, two) of inkjet heads 211 from the liquid sending common flow path 256, that is switches the communicating state and the non-communicating state between the individual flow paths 257 and the inkjet head 211. In normal image forming, all of these individual supplying valves 258 are opened. When the ink in the intermediate tank 262 and the liquid sending common flow path 256 is not ejected outside but is returned to the sub-tank 251 and collected, the individual supplying valves 258 are 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 the some of the inkjet heads 211, only the individual supplying valve 258 provided in the individual flow path 257 communicating with the above-described some of the inkjet heads 211 is opened, and the other individual supplying valve 258 is closed.
Here, four individual flow paths 257 are shown as an example. This number can be suitably set as long as problems do not occur when the ink is supplied to the inkjet head 211 or when ink is ejected from the nozzle.
FIG. 3 is a diagram showing an example of a cross-sectional configuration of the individual supplying valve 258 according to the present embodiment.
As the individual supplying valve 258 or the valve which switches the flow of the ink, here, an electromagnetic valve is used. For example, a solenoid valve is used to switch between open and close of the flow path by moving the plunger (movable iron piece) 2581 provided in the flow path of the ink using electromagnetic force or spring force. The plunger 2581 is positioned along the flow path direction of the ink. When predetermined voltage is applied to the solenoid 2582 according to control by the controller 40 (see FIG. 4), the plunger 2581 moves against the repulsion force of the spring 2583 toward the downstream side (side of the inkjet head 211) so as to block the ink flow path. When the voltage is released, the plunger 2581 returns to the original upstream side position according to the repulsion force of the spring 2583 and the ink flow path is opened. The outlined valve in FIG. 2 such as the individual supplying valve 258 is the valve in the open state in the normal state (in ground voltage supplying state or when voltage is not supplied). The black colored valve in FIG. 2 such as the intermediate tank distributing valve 261 is a valve in a closed state in the normal state.
The moving speed of the plunger 2581 is sufficiently fast and immediately switches between open and closed. In response to such movement, the pressure wave occurs in the ink. Due to the collision between the moved plunger 2581 and the outer frame of the individual supplying valve 258, a mechanical shock may occur.
The damper 259 is a buffer which reduces the pressure change according to the status of the ink ejecting from the plurality of inkjet heads 211 and the status of the liquid sent from the liquid sending pump 253. The damper 259 includes a flexible film, and receives the change in pressure regarding the operation of the other inkjet heads 211 and the liquid sending pump 253 by bending. This suppresses the spread of the change in pressure. By providing pressure in a suitable pressure pattern to the ink in the inkjet head 211 when the ink is ejected from the inkjet head 211, the ink can be ejected normally. Frequency of the change of pressure mainly reduced by the damper 259 is a frequency smaller than the frequency of the pressure wave of the ink according to the movement of the above-described plunger 2581.
A plurality of nozzles are arrayed in the inkjet head 211. The ink supplied from the damper 259 to the inkjet head 211 is further divided to ink flow paths communicating with each nozzle. The ink flow path is provided with a pressure chamber (not shown). By providing pressure in a suitable waveform to the ink in the pressure chamber, the ink is ejected or the ink which is not ejected is suitably shaken in the nozzle to prevent drying or deteriorating of the ink. The method to apply pressure to the ink in the pressure chamber can be selected from various well-known methods. Here, the piezo method is employed, and voltage is applied using a piezoelectric element or vibrating plate to deform the pressure chamber to change the pressure on the ink. Near the entrance of the nozzles, the ink liquid surface (meniscus surface) is suitably maintained. With this, pressure is applied and droplets in a suitable shape and size are separated from the ink in the nozzle and ejected.
The check valve 271 allows the discharged ink which is not ejected by the nozzle from the inkjet head 211 to flow to the common collecting common flow path 272 and prevents the ink from flowing backward from the collecting common flow path 272 to the inkjet head 211. That is, the ink discharged from some of the inkjet heads 211 do not flow backwards to the other inkjet heads 211.
An intermediate tank distributing valve 261 is provided near an entrance of the intermediate tank flow path 260 separated from the maintenance flow path 265 downstream of the deaerating module 255 and opens and closes according to whether the ink can flow to the intermediate tank flow path 260. The intermediate tank flow path 260 is open when the ink is supplied to the inkjet head 211 in normal image forming.
The intermediate tank 262 is a tank with a smaller capacity than the sub-tank 251 and is used to maintain the ink in the inkjet head 211 to a suitable back pressure (predetermined setting value), that is, pressure lower than the atmospheric pressure (negative pressure). Therefore, the intermediate tank 262 is formed with a flexible material and can suitably deform by the difference in pressure between the ink pressure and the outside pressure. The intermediate tank 262 is provided in a position slightly lower in the vertical direction than the nozzle surface on which the nozzle opening of the inkjet head 211 is aligned. As a result, by applying further pressure to the ink by the liquid sending pump 253 and the pressure chamber in the inkjet head 211, the ink does not leak out naturally from the nozzle opening other than when the ink is ejected intentionally. When the ink is ejected from the nozzle opening and the ink of the inkjet head 211 decreases, the ink flows from the intermediate tank 262 to the inkjet head 211 according to the reduction amount (ink ejecting amount).
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 the intermediate reference ink amount (that is, indirectly, the suitable back pressure itself) suitably set to obtain the suitable back pressure. The operation of the liquid sending pump 253 is suitably controlled according to whether the ink is detected in the intermediate reference ink amount by the intermediate reference sensor 262b. The intermediate upper limit sensor 262a detects the upper limit ink amount determined so as not to be dangerous to maintain the intermediate tank 262. Normally, when the ink amount in the intermediate tank 262 rises more than normal and the pressure of the ink rises, the check valve 283 is released and the ink is returned to the sub-tank 251. When the check valve 283 does not function normally, the process regarding the operation of supplying ink can be paused entirely or other suitable processes can be performed depending on the detection by the intermediate upper limit sensor 262a.
The maintenance flow path distributing valve 266 switches whether the ink sent out from the liquid sending pump 253 can be flown into the maintenance flow path 265. As shown here, the maintenance flow path distributing valve 266 and the intermediate tank distributing valve 261 can be closed at the same time. For example, when the image is formed, if the ink amount in the intermediate tank 262 is within a suitable range and there is no need to additionally supply ink to the intermediate tank 262 with the liquid sending pump 253, both the maintenance flow path distributing valve 266 and the intermediate tank distributing valve 261 are closed.
The maintenance flow path 265 is used when the ink is pressured and sent by the liquid sending pump 253 as is to the liquid sending common flow path 256 and the inkjet head 211 for the purpose of introducing ink, ejecting air (bubbles) and flowing the factors causing clogging. For example, when all of the individual supplying valves 258 are closed and the pressured ink is sent while opening the bypass valve 270, the ink is introduced to the liquid sending common flow path 256 and the ink is flown to flow the internal air to the collecting flow path 27 and the sub-tank 251. When the pressured ink is sent by the liquid sending pump 253 in a state with all of the individual supplying valves 258 and the collecting valves 273 open, the ink is filled in the ink flow path in each inkjet head 211. When the pressured ink is sent by the liquid sending pump 253 with one or all of the individual supplying valves 258 opened and the collecting valve 273 closed, the pressured ink is ejected from the nozzles of the inkjet head 211, and the bubbles in the nozzle are discharged. With this, the cause of clogging in the nozzle opening such as solidified or thickened mass of ink is discharged and the clogging is solved. Here, by reducing the number of individual supplying valves 258 which are opened, the pressure of the ink supplied to the inkjet head 211 regarding the opened individual supplying valves 258 can be relatively increased.
The common supplying valve 263 switches whether ink can be supplied from the intermediate tank 262 to the liquid sending common flow path 256 and the inkjet heads 211. In the closed state, when the pressured ink is supplied to the common flow path through the maintenance flow path 265, the common supplying valve 263 prevents the ink from flowing backward to the intermediate tank 262.
The collecting common flow path 272 which joins the discharged ink which is not ejected from the inkjet head 211 and flows the ink to the sub-tank 251 side has substantially the same configuration as the liquid sending common flow path 256 and for example, is shaped in a tube shape. Both the liquid sending common flow path 256 and the collecting common flow path 272 are formed sufficiently larger (cross-sectional area is larger) than the individual flow path 257. This suppresses the influence from the change in the flow amount and the ink pressure regarding the change in the ink supply amount to the individual flow path 257 from spreading.
The collecting valve 273 switches whether to return the ink from the collecting common flow path 272 to the sub-tank 251. The collecting valve 273 is closed when the bypass valve 270 is opened so that the ink flowing from the liquid sending common flow path 256 to the bypass valve 270 does not return to the collecting common flow path 272.
The ink passing the bypass valve 270 or the collecting valve 273 passes the circulating valve 274 or the collecting pump 275 (ink drawing unit) and returns to the sub-tank 251. When the ink sent out from the liquid sending pump 253 and not ejected from the nozzle of the inkjet head 211 is drawn and returned to the sub-tank 251, the circulating valve 274 is closed and the collecting pump 275 is operated. With this, the ink remaining in the inkjet head 211 or in each unit such as the intermediate tank 262 is drawn and returned to the sub-tank 251. Therefore, the ink can be removed from the inkjet head 211 and inside the intermediate tank 262.
The pressure reducing unit includes the bypass valve 270 and the collecting pump 275.
Further, the collecting pump 275 not only draws the ink but also draws the air in the ink flow path. When the ink is not supplied to the circulating flow path, such as in the default state or when restarted after maintenance, the collecting pump 275 draws the air in the circulating flow path. Specifically, by removing almost all of the air in the intermediate tank 262 and then introducing the ink in the intermediate tank 262 with the liquid sending pump 253, it is possible to prevent the air remaining in the intermediate tank 262 causing unnecessary pressure or the air being mixed with the ink and flown to the inkjet head 211 causing trouble in ejecting ink. Normally, when the ink is introduced, the removal of air and the collecting of ink by the collecting pump 275 and the introduction of ink by the liquid sending pump 253 is repeated a plurality of times. With this, it is possible to easily introduce ink while reliably preventing the air from remaining in the circulating flow path, specifically, between the sub-tank 251 and the inkjet head 211.
When there is no need to remove the ink inside the inkjet head 211 and the intermediate tank 262, and the ink sent by the liquid sending pump 253 is simply circulated, the circulating valve 274 is opened without operating the collecting pump 275. With this, the circulating flow of the ink is caused only by the liquid sending pressure of the liquid sending pump 253.
A discharge valve is provided on the downstream side of the filter 254, downstream of the intermediate tank 262, and in the liquid sending common flow path 256. The user opens the discharge valve as necessary so as to be able to discharge ink.
Next, the functional configuration of the inkjet recording device 100 according to the present embodiment is described.
FIG. 4 is a block diagram showing a functional configuration of the inkjet recording device 100.
The inkjet recording device 100 is provided with the following which are described above, the supplying pump 32, the liquid sending pump 253, the collecting 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, the pressure sensor 294, the liquid amount sensor 292a, the intermediate tank distributing valve 261, the maintenance flow path distributing valve 266, the common supplying valve 263, the individual supplying valve 258, the bypass valve 270, the collecting valve 273, the circulating valve 274, the conveying motor 12, the electromagnetic brake 233, the raising/lowering motor 232, and the reader 24. In addition to the above, the inkjet recording device 100 is provided with a controller 40 (pressuring supplying controller, pressuring controller), a communicating unit 41, an operation/display unit 42, a conveying motor 12, a head driving unit 221, a motor driver 231, a notification operating unit 43 and a bus 49.
The controller 40 centrally controls the entire operation of the inkjet recording device 100 and controls the operation of each unit. The controller 40 includes a CPU 401 (Central Processing Unit), a RAM 402 (Random Access Memory), a ROM 403 (Read Only Memory) and a memory 404.
The CPU 401 performs various calculating processes and controls the conveying of the recording medium, supplying of the ink, ejecting of the ink, maintenance operation and the like in the inkjet recording device 100. The CPU 401 performs various processes regarding the image forming based on the image data, and status signals and clock signals of each unit according to the programs read from the ROM 403.
The RAM 402 provides a memory space for work in the CPU 401 and stores temporary data.
The ROM 403 stores the control program and the default setting data. The control program includes programs regarding the control of the ink supply and the maintenance operation of the inkjet recording device 100.
The ROM 403 includes a rewritable nonvolatile memory and stores an individual maintenance executing flag 403a showing whether the later-described individual maintenance is executed. The memory 404 includes a RAM which temporarily stores the image data to be formed.
The head driving unit 221 generates and outputs a driving voltage signal which deforms the pressure chamber (piezoelectric element) to suitably eject the ink from the nozzle in each inkjet head 211. The head driving unit 221 selects a voltage waveform pattern stored in advance based on the control signal from the controller 40 and generates the driving voltage signal with the power amplified. The head driving unit 221 switches whether to output the driving voltage signal on each piezoelectric element according to the image data input from the memory 404.
The wiring regarding the head driving unit 221 is formed collectively with the ink flow path in the inkjet head 211, and a portion is formed separately.
The motor driver 231 outputs a driving signal to the electromagnetic brake 233 and the raising/lowering motor 232 according to the control signal from the controller 40. With this, the carriage is moved to a predetermined positon by loosening the electromagnetic brake 233 and operating the raising/lowering motor 232. Alternatively, the raising/lowering motor 232 is stopped to fix the carriage with the electromagnetic brake 233.
The communicating unit 41 is the communication interface which controls the communication operation with the external devices. One or a plurality of communication interfaces such as a LAN board, a LAN card or the like which can handle various communication protocols are included. The communicating unit 41 obtains image data to be formed or setting data (job data) regarding the image forming from external devices based on control of the controller 40. The communicating unit 41 can also transmit status information to the external devices.
The operation/display unit 42 displays the status of the inkjet recording device 100 and the operating menu according to the control signal from the controller 40 and receives the operation by the user to be output to the controller 40. For example, the operation/display unit 42 includes a liquid crystal display provided with a touch sensor as the operation receiving unit overlapped with the display screen as a display unit. The controller 40 displays on the liquid crystal display the status or various menus to receive instructions on the touch sensor. The controller 40 controls each unit of the inkjet recording device 100 to perform processes according to the information of the contents and position of the displayed menu and the touch operation by the user detected by the touch sensor.
The notification operating unit 43 performs predetermined notification operation according to the control signal of the controller 40. For example, the configuration which performs the notification operation includes, an LED lamp which emits light at a predetermined color and/or a beep sound generating unit which generates a beep sound.
In addition to the above, the inkjet recording device 100 may include a placement abnormality detecting sensor which detects that the supplied recording medium is not placed on the conveying surface normally.
The bus 49 is a path electrically connected to the components to communicate signals.
Next, maintenance operation of the inkjet head 211 in the inkjet recording device 100 according to the present embodiment is described.
In the inkjet recording device 100 according to the present embodiment, when clogging in a specific nozzle of the inkjet head 211 occurs or bubbles are mixed and the ink cannot be normally ejected, ink is selectively pressured and sent to the inkjet head 211. With this, the specific maintenance process which flows out clogging and bubbles from the nozzle opening is performed.
Here, the pressure applied to the ink (liquid sending amount of ink) by the liquid sending pump 253 is a fixed value. Therefore, the pressure applied to the nozzles is in inverse proportion with the sum of the square area of the opening of the nozzles, that is, the number of selected nozzles. In the independent maintenance, when the number of inkjet heads 211 as the object of maintenance becomes equal to or more than a predetermined maximum supply number to send ink to the nozzles at a predetermined pressure or more, the recording heads as the object of maintenance are divided into a plurality of groups, and the ink is pressured and sent in the unit of groups.
FIG. 5 is a flowchart showing a control process by the controller 40 to perform the individual maintenance process executed in the inkjet recording device 100 according to the present embodiment.
The individual maintenance process is started automatically or by predetermined input from the user when problems such as ink ejecting problems occurring in any of the nozzles of the inkjet head 211 are detected by the inspection of the recorded image. The inkjet head 211 selected as the target of sending pressured ink is set by the user confirming the inspection image by sight or the controller 40 determining automatically based on the inspection image. Preferably, the inspection image includes numbers or symbols for each inspection image by each inkjet head 211 so that the user is able to easily select the inkjet head 211.
The controller 40 (CPU 401) closes the common supplying valve 263 (step S101). The controller 40 closes the intermediate tank distributing valve 261 and opens the maintenance flow path distributing valve 266 (step S102). With this, the intermediate tank 262 is separated from the ink flow path from the liquid sending pump 253 to the liquid sending common flow path 256.
The controller 40 closes the individual supplying valve 258 in communication with the inkjet head 211 which is not the target of pressuring the ink and sending the ink (step S103). The controller 40 closes the bypass valve 270 and the collecting valve 273. Then, the controller 40 operates the liquid sending pump 253 and pressures and sends ink to the inkjet head 211 as the target of pressured sending (maintenance target) (step S104). Here, the bypass valve 270 and the colleting valve 273 are closed, and the ink supplied to the inkjet head 211 can be flown only from the nozzle opening of the inkjet heads 211. Therefore, the clogging and the bubbles in the nozzle of the inkjet head 211 are pushed out from the nozzle opening.
The controller 40 opens the bypass valve 270 and the collecting valve 273 and releases and reduces the pressure in the liquid sending common flow path 256 and the inkjet head 211 raised by the operation of the liquid sending pump 253 (step S105). The controller 40 determines whether the pressuring on all of the inkjet heads 211 as the target of pressured sending is finished (step S106). When it is determined that the pressuring is not finished ("NO" in step S106), the controller 40 returns the process to step S103.
When it is determined that the ink is pressured and sent in the ink flow path of all inkjet heads 211 as the target of pressured sending ("YES" in step S106), the controller 40 closes the maintenance flow path distributing valve 266 and opens the intermediate tank distributing valve 261 and the common supplying valve 263 (step S107). With this, the pressure of the ink in the intermediate tank 262 rises according to the amount of increase in the pressure of the ink in the ink sending common flow path 256.
The controller 40 closes all of the individual supplying valves 258 (step S108). Here, the bypass valve 270 and the collecting valve 273 are opened. The controller 40 operates the collecting pump 275 to draw in the ink in the intermediate tank 262 and performs adjustment to decrease the pressure (ink amount) in the intermediate tank 262 to a set value (step S109).
The controller 40 closes the bypass valve 270 and the collecting valve 273 and opens all of the individual supplying valves 258 (step S110). Here, together with the opening of the individual supplying valves 258, the meniscus shape of the liquid surface of each nozzle in the inkjet head 211 may be destroyed. The controller 40 operates the liquid sending pump 253 to pressure and supply ink to all of the recording heads. With this, the ink is pushed out from each nozzle and the meniscus shape of the liquid surface in each nozzle is formed again (step S111; pressure control step).
The controller 40 operates the conveying motor 12 and the head driving unit 221 to record the predetermined inspection image on the recording medium (step S112). The controller 40 operates the reader 24 so that the reader 24 reads the recorded inspection image to detect abnormalities regarding ink ejection from the inspection image. The controller 40 determines whether there is a problem in the inspection image (step S113). When there is a problem (determined not OK) ("NO" in step S113) the process is returned to step S101 and the process is performed again from the beginning. When it is determined that there is no problem (determined OK) ("YES" in step S113), the controller 40 ends the individual maintenance process.
Here, the process from step Sill and after does not have to be immediately performed after the process of step S110. For example, when the process in step S110 is performed, the controller 40 sets the individual maintenance executing flag 403a and performs the process from step Sill and after according to the individual maintenance executing flag 403a before the next image recording starts. After performing the process, the individual maintenance executing flag 403a may be reset.
The process of steps S112, S113 do not have to be performed in the independent maintenance process, and can be performed in the normal image recording operation or as a part of the normal inspection process when the inkjet recording device 100 is started.
As described above, the inkjet recording device 100 according to the present embodiment includes a plurality of inkjet heads 211 including a nozzle which ejects ink, an individual flow path 257 and liquid sending common flow path 256 which introduce ink to each of the plurality of inkjet heads 211, an individual supplying valve 258 which switches the connecting state and the non-connecting state between the individual flow path 257 and the inkjet head 211 corresponding to the individual flow path 257, the liquid sending pump 253 which pressures and sends ink into the inkjet head 211 through the liquid sending common flow path 256 and the individual flow path 257, and a controller 40 as a pressuring controller which, after pressuring and sending ink into some of the inkjet heads 211 corresponding to some of the individual supplying valves 258 opened among the individual supplying valves 258, all of the individual supplying valves 258 are opened and the ink is pressured and sent to all of the inkjet heads 211.
With this, according to selective opening and closing of the individual supplying valves 258, ink is pressured and sent to some of the inkjet heads 211. With this, pressuring maintenance can be performed in the inkjet head 211 to effectively discharge clogging in the nozzle, thickened ink, dust, and bubbles. Moreover, after the closed individual supplying valves 258 are reopened, ink is pressured and sent to all of the inkjet heads 211 again to discharge the ink. With this, the meniscus surface of the ink in the nozzle which may be destroyed when the individual supplying valve 258 is reopened can be restored. With this, the ink can be ejected normally and reliably in the image recording from then after. Therefore, according to the inkjet recording device 100, the meniscus surface of the ink can be suitably and easily maintained while performing pressuring maintenance selectively on some of the recording heads.
The intermediate tank flow path 260 which passes the ink through the intermediate tank 262 and the maintenance flow path 265 which flows the ink without passing through the intermediate tank 262 are provided parallel between the liquid sending pump 253 and the liquid sending common flow path 256. The intermediate tank distributing valve 261 and the common supplying valve 263 which switch whether ink can be flown in to or out of (liquid flow in/out) the intermediate tank 262 are provided in the intermediate tank flow path 260. The maintenance distributing valve 266 which opens and closes the maintenance flow path 265 is provided in the maintenance flow path 265. When the ink is pressured and sent in a state with some of the individual supplying valves 258 opened, the controller 40 closes the intermediate tank distributing valve 261 and the common supplying valve 263, and the maintenance flow path distributing valve 266 is opened.
With this, pressured ink can be supplied to the inkjet head 211 efficiently without causing excess pressure loss in the intermediate tank 262. Strong pressure is not applied to the intermediate tank 262 and therefore, the intermediate tank 262 is not damaged.
The bypass valve 270 and the collecting pump 275 which decrease the pressure of the ink in the liquid sending common flow path 256 and individual flow path 257 are provided , and after the ink is pressured and sent to some of the inkjet heads 211, before all of the individual supplying valves 258 are opened, the controller 40 opens the bypass valve 270 to release the pressure to the sub-tank 251 in communication with the atmosphere and to reduce the pressure of the ink in the liquid sending common flow path 256, and opens the common supplying valve 263.
This prevents the ink pressured in the liquid sending common flow path 256 from flowing backward to the intermediate tank 262 and the pressure in the intermediate tank 262 from rising more than necessary.
The collecting pump 275 which draws in ink of the liquid sending common flow path 256 is provided. Therefore, when the ink pressure in the liquid sending common flow path 256 is not completely decreased by only opening the bypass valve 270, or when the decrease in ink pressure needs more time than the desirable amount of time, the ink pressure can be decreased efficiently by drawing in ink with the collecting pump 275.
After the common supplying valve 263 is opened, the controller 40 controls the collecting pump 275 to draw in the ink of the liquid sending common flow path 256 and the intermediate tank 262 so that the ink pressure of the intermediate tank 262 becomes a suitable value.
With this, the pressure (that is, ink amount) in the intermediate tank 262 is adjusted to a level suitable for recording the image. After the individual maintenance process, it is possible to immediately return to the normal image recording operation.
The sub-tank 251 which stores ink pressured and supplied by the liquid sending pump 253 and the collecting flow path 27 which returns the ink drawn in by the collecting pump 275 to the sub-tank 251 are provided. Therefore, the ink which is not ejected or leaked from the nozzle of the inkjet head 211 can be effectively used again. Consequently, the amount of wasted ink can be reduced.
The controller 40 functions as the pressuring and supplying controller and performs the pressuring and supplying of the ink by dividing the inkjet heads 211 in a predetermined maximum supply number or less. Therefore, when the number of inkjet heads 211 as the target of pressuring and supplying ink separately is large, the number of inkjet heads 211 is divided in a suitable number or less. With this, the pressure of the ink pressured and supplied to each inkjet head 211 can be maintained at a level necessary for individual maintenance, and clogging, thickening ink, debris, and bubbles can be ejected effectively.
The maintenance method of the above-described inkjet recording apparatus 100 is used to suitably maintain the meniscus surface of the ink easily and simply while selectively performing pressuring maintenance on some of the recording heads.
The present invention is not limited to the above-described embodiments and various modifications are possible.
For example, according to the present embodiment, an intermediate tank 262 is provided between the sub-tank 251 and the inkjet head 211 and the intermediate tank 262 performs supply of ink to the inkjet head 211 regarding normal image recording. Alternatively, an ink flow path which passes through the liquid sending pump 253 and an ink flow path which does not pass through the liquid sending pump 253 can be provided in parallel between the sub-tank 251 and the inkjet head 211. With this, the ink can be directly supplied to the inkjet head 211 from the sub-tank 251.
According to the above-described embodiment, a common individual supplying valve 258 is provided for two inkjet heads 211. Alternatively, one individual supplying valve 258 can be provided for each inkjet head 211.
According to the above-described embodiment, all of the processes regarding the individual maintenance process are performed based on the control by the controller 40. Alternatively, some of the processes can be performed based on input operation by the user.
For example, the selection of the inkjet head 211 as the target of individual maintenance can be performed based on input by the user, and the operation/display unit 42 can display on the display screen a display to urge the user to make a selection each time the process in step S106 is performed.
For example, when the process in step S110 is performed and the individual maintenance executing flag 403a is set, the controller 40 displays on the display screen of the operation /display unit 42 a display to request input operation of the instruction to execute the process of step Sill. This display can be maintained until the user instructs the process of step Sill to be performed at a desired timing by predetermined input operation.
According to the present embodiment, the ink which is not ejected or leaked is collected and returned to the sub-tank 251. Alternatively, such circulating path of the ink may not be provided and the ink once sent to the inkjet head 211 may be entirely ejected or discharged.
In this case, the ink may be discharged from the intermediate tank 262 by providing a discharge valve which flows out ink according to gravity instead of using a collecting pump 275.
According to the present embodiment, a solenoid valve is described as an example. The type of individual supplying valve 258 is not limited as long as pressure waves occur in the ink in response to opening/closing of the movable portion.
According to the above-described embodiment, the inkjet recording device including a line head which ejects ink with a plurality of colors is described. Alternatively, the number of colors of ink which can be ejected can be set freely. Instead of the line head, the present invention can be applied to a scan-type inkjet recording device which records the image by ejecting ink while the inkjet head 211 scans the recording medium. The present invention is not limited to the inkjet recording device and can be various droplet ejecting devices which obtain a film or a structure by ejecting the droplets of a liquid other than ink from the nozzle.
The specific details of the configuration, positions, and contents of control shown in the above-described embodiment can be suitably changed without leaving the scope of the present invention.

Industrial Applicability

The present invention can be used in a droplet ejecting device and a method for maintenance of the droplet ejecting device.

Description of Reference Numerals

10 conveying unit
11 driving roller
12 conveying motor
14 conveying belt
20 image forming unit
211 inkjet head
22 carriage
221 head driving unit
23 carriage raising/lowering unit
231 motor driver
232 raising/lowering motor
233 electromagnetic brake
234 beam member
235 supporting unit
24 reader
251 sub-tank
251a reference sensor
251b lower limit sensor
251c upper limit sensor
252 flowmeter
253 liquid sending pump
254 filter
255 deaerating module
256 liquid sending common flow path
257 individual flow path
258 individual supplying valve
2581 plunger
2582 solenoid
2583 spring
259 damper
260 intermediate tank flow path
261 intermediate tank distributing valve
262 intermediate tank
262a intermediate upper limit sensor
262b intermediate reference sensor
263 common supplying valve
265 maintenance flow path
266 maintenance flow path distributing valve
27 collecting flow path
270 bypass valve
271 check valve
272 collecting common flow path
273 collecting valve
274 circulating valve
275 collecting pump
281 to 283 check valve
29 absorbing unit
291 check valve
292 chamber
292a liquid amount sensor
293 vacuum pump
294 pressure sensor
30 ink storage unit
31 main tank
32 supplying pump
35 rack
40 controller
401 CPU
402 RAM
403 ROM
403a individual maintenance executing flag
404 memory
41 communicating unit
42 operation/display unit
43 notification operating unit
49 bus
100 inkjet recording device

Claims

A droplet ejecting device comprising:
a plurality of ejecting heads including a nozzle which ejects droplets;

a liquid flow path which introduces to each of the plurality of ejecting heads liquid which is to be ejected;

an individual opening/closing unit which switches a communicating state and a non-communicating state between the liquid flow path and the plurality of ejecting heads for each of at least two or more groups;

a liquid sending unit which pressures and sends the liquid into the ejecting head through the liquid flow path; and

a pressuring controller which, after pressuring and sending liquid into some of the ejecting heads corresponding to the some of the individual opening/closing units in a state in which the some of the individual opening/closing units are open, opens all of the individual opening/closing units and pressures and sends the liquid to all of the ejecting heads.
The droplet ejecting device according to claim 1, wherein,
the liquid flow path includes, an intermediate flow path which flows the liquid through an intermediate storage and a detouring flow path which is provided parallel with the intermediate flow path and which does not pass the liquid through the intermediate storage;

the intermediate flow path is provided with an intermediate storage opening/closing unit which switches whether the liquid can flow into or out of the intermediate storage;

the detouring flow path is provided with a detouring flow path opening/closing unit which opens and closes the detouring flow path; and

the pressuring controller closes the intermediate storage opening/closing unit and opens the detouring flow path opening/closing unit when the liquid is pressured and sent in the state in which the some of the individual opening/closing units are open.
The droplet ejecting device according to claim 2, further comprising a pressure reducing unit which reduces pressure of the liquid in the liquid flow path,
wherein, after pressuring and sending the liquid to the some of the ejecting heads, before opening all of the individual opening/closing units, the pressuring controller controls the pressure reducing unit to reduce the pressure of the liquid in the liquid flow path and opens the intermediate storage opening/closing unit.
The droplet ejecting device according to claim 3, wherein the pressure reducing unit includes a drawing unit which draws in liquid of the liquid flow path.
The droplet ejecting device according to claim 4, wherein after the intermediate storage opening/closing unit is opened, the pressuring controller controls the drawing unit to draw in the liquid of the liquid flow path and the intermediate storage to set the pressure of the liquid in the intermediate storage to a predetermined set value.
The droplet ejecting device according to claim 4 or 5, further comprising:
a storage which stores liquid which the liquid sending unit pressures and sends to the ejecting head; and

a collecting flow path which returns the liquid drawn in by the drawing unit to the storage.
The droplet ejecting device according to any one of claims 1 to 6, further comprising a pressuring supplying controller which pressures and supplies the liquid to each group of ejecting heads, the ejecting heads divided into groups of a predetermined maximum supply number or less.
The method for maintaining a droplet ejecting device, the droplet ejecting device including, a plurality of ejecting heads including a nozzle which ejects droplets; a liquid flow path which introduces to each of the plurality of ejecting heads liquid which is to be ejected; an individual opening/closing unit which switches a communicating state and a non-communicating state between the liquid flow path and the plurality of ejecting heads for each of at least two or more groups; and a liquid sending unit which pressures and sends liquid into the ejecting head through the liquid flow path, the method comprising:
controlling pressuring, after pressuring and sending liquid into some of the ejecting heads corresponding to the some of the individual opening/closing units in a state in which the some of the individual opening/closing units are open, to open all of the individual opening/closing units and to pressure and send the liquid to all of the ejecting heads.