WO2015029599A1

WO2015029599A1 - Ink supply unit, ink supply method, and inkjet printing device

Info

Publication number: WO2015029599A1
Application number: PCT/JP2014/068027
Authority: WO
Inventors: 哲之岡山
Original assignee: 富士フイルム株式会社
Priority date: 2013-08-28
Filing date: 2014-07-07
Publication date: 2015-03-05
Also published as: JP2015044344A

Abstract

Provided are an ink supply unit and ink supply method capable of maintaining a constant amount of dissolved oxygen in the ink, and an inkjet printing device. The ink supply unit is provided with: an ink tank (52); an inkjet head (50); a circulation flow channel (300) for circulating ink between the ink tank (52) and the inkjet head (50); a replenishment flow channel (316), which is connected to a recovery flow channel (112) and replenishes ink in the ink tank (52) from a main tank (56); and a deaeration means (160) provided between the confluence of the recovery flow channel (112) with the replenishment flow channel (316) and the ink tank (52). The feed rate for ink flowing through the replenishment flow channel (316) during ink replenishment in which ink is replenished in the ink tank (52) from the main tank (56) is made to be slower than the feed rate for ink flowing through the recovery flow channel (112) during non-replenishing circulation, and the feed rate for ink flowing through the recovery flow channel (112) during ink replenishment is made to be slower than the feed rate for ink flowing through the recovery flow channel (112) during non-replenishing circulation.

Description

Ink supply apparatus, ink supply method, and ink jet recording apparatus

The present invention relates to an ink supply device, an ink supply method, and an ink jet recording apparatus, and more particularly, to an ink supply device, an ink supply method, and an ink jet recording apparatus that circulate between an ink discharge portion and a storage portion.

In recent years, there has been an increasing demand for small copies in the printing industry. In offset printing, since it is necessary to create a plate, when printing a small number of copies, there has been a problem in terms of time and cost. For this reason, single-pass inkjet recording is preferably used.

However, the single-pass method has a drawback that streaks are likely to be noticeable in the missing part if there is a nozzle that does not discharge or a nozzle that causes discharge bending. A major factor causing streaks is that air bubbles are mixed in the head (increase in the amount of dissolved oxygen). By providing a degassing module in the circulation path to remove bubbles, the amount of dissolved oxygen in the ink is kept at a low level during the circulation. However, when degassed ink is consumed by printing, the ink that has not been degassed is replenished, and the ink that has not been degassed is supplied into the head, so that ink with a high dissolved oxygen amount is discharged. , Leading to degradation of print quality.

In order to suppress the amount of dissolved oxygen during printing, in Patent Document 1, when the ink in the sub tank is circulated through a circulation path including a degassing filter and ink is replenished from the main tank to the sub tank, A liquid ejection device is described that passes a degassing filter. Thereby, the ink in the sub tank and the ink in the main tank can be deaerated.

JP 2006-247450 A

However, the liquid ejection device described in Patent Document 1 circulates ink in the circulation path in a steady state so that the ink can be circulated through the deaeration module many times. It can be done sufficiently. However, when ink is replenished, the ink is ejected from the head after passing through the deaeration module once, so that the ink has not been sufficiently deaerated.

The present invention has been made in view of such circumstances, and can suppress the amount of dissolved oxygen in ink when refilling ink at the time of printing, and can maintain a constant amount of dissolved oxygen in the ink supplied to the inkjet head. It is an object to provide a supply device, an ink supply method, and an ink jet recording apparatus.

In order to achieve the above object, the present invention provides an ink tank for storing ink, an ink jet head, a supply channel for supplying ink from the ink tank to the ink jet head, and a recovery flow for collecting ink from the ink jet head to the ink tank. And a circulation flow path including a replenishment flow path, a replenishment flow path connected to the collection flow path, and a main that is connected to the replenishment flow path and stores ink for refilling the ink tank. A common flow that is provided between the ink tank and the ink tank by the circulation flow path and the flow path at the time of ink replenishment by the replenishment flow path is provided between the merging point of the tank and the replenishment flow path of the collection flow path. A deaeration means for deaerating the ink flowing through the path portion, and supplying the ink flowing through the replenishment flow path when refilling ink from the main tank to the ink tank. The speed is made slower than the liquid feeding speed of the ink flowing through the collection flow path during the non-replenishment circulation in which the ink is circulated through the circulation flow path when the ink is not replenished from the main tank to the ink tank. Provided is an ink supply device that makes a liquid feeding speed of ink flowing through a collecting flow path slower than a liquid feeding speed of ink flowing through a collecting flow path during non-replenishment circulation.

According to the present invention, since the deaeration means is provided between the ink tank and the confluence of the replenishment flow path of the recovery flow path, both the ink circulating in the circulation flow path and the ink refilled from the main tank are removed. It can deaerate by deaeration means. Therefore, by providing one deaeration means in the ink supply device, the ink can be degassed, so that the size and cost of the device can be reduced. Further, the ink is replenished from the main tank by making the ink feeding speed flowing from the main tank to the ink tank through the replenishing flow path at the time of ink replenishment slower than the liquid feeding speed of the ink flowing through the collecting flow path at the time of non-refilling circulation. Since the time for the ink to pass through the degassing means can be lengthened, the degassing means can sufficiently degas the ink. “Non-replenishment circulation” means that the ink flows only through the ink tank, supply flow path, inkjet head, and recovery flow path, and the ink is not replenished from the replenishment flow path. is there. Further, the ejection of ink from the inkjet head is not particularly limited.

In an ink supply apparatus according to another aspect of the present invention, a replenishment flow path is provided with a replenishment pump for feeding ink, and a replenishment flow rate of ink fed by the replenishment pump is set to ym / min. When the amount of ink used is xml / min, it is preferable to satisfy the relationship of x ≦ y.

According to the ink supply device of another aspect of the present invention, the ink consumed by printing can be replenished by increasing the replenishment flow rate from the main tank. Note that “the amount of ink used for printing by the ink jet head” is an average value of the amount of ink consumed for printing within a certain predetermined range.

In the ink supply device according to another aspect of the present invention, it is preferable that ink replenishment is performed during printing with an inkjet head.

According to the ink supply device according to another aspect of the present invention, even when ink is printed, the deaeration of the ink replenished from the main tank to the replenishment flow path can be sufficiently performed by passing the deaeration means once. Ink can be deaerated. In addition, since the ink can be sufficiently deaerated by slowing the liquid feeding speed of the ink flowing through the recovery flow path, the ink can be deaerated while ejecting the ink from the inkjet head.

In the ink supply device according to another aspect of the present invention, when ink is replenished, the liquid feeding speed of the ink flowing through the supply flow path may be slower than the liquid feeding speed of the ink flowing through the supply flow path during non-replenishment circulation. preferable.

According to the ink supply device according to another aspect of the present invention, when the ink is replenished, the liquid feeding speed of the ink flowing through the recovery flow path is slowed down, so the liquid feeding speed of the ink flowing through the supply flow path is also slowed down Thus, the back pressure in the ink jet head can be adjusted.

In order to achieve the above object, the present invention provides an ink jet head having a supply port for supplying ink, a nozzle for discharging ink, and a discharge port for discharging ink that has not been discharged, and the ink described above An ink jet recording apparatus comprising a supply device.

By using the ink supply device described above, the ink in the ink supply device can be sufficiently deaerated, so that the ink supply device can be suitably used.

In order to achieve the above object, the present invention provides a supply step of supplying ink from an ink tank to an ink jet head into a circulation flow path including the ink tank and the ink jet head, and supplying ink from the ink jet head to the ink tank. A replenishing flow path for connecting the main tank for storing the ink and the ink collecting side of the circulation flow path. Through the replenishment step of replenishing the ink in the main tank to the ink tank, the deaeration step of degassing the ink collected in the recovery step, and the ink replenished in the replenishment step, and removing the ink in the replenishment step. During the deaeration process, the ink feeding speed in the replenishment process is slower than the ink feeding speed in the collection process during the non-replenishment circulation that circulates in the circulation channel. And, and, to provide an ink supply method of the feed rate of the ink recovery steps slower than feed rate of the unsupplemented circulation during the recovery step.

In the ink supply method according to another aspect of the present invention, if the replenishment flow rate of the ink fed in the replenishment step is ym / min, and the amount of ink used for printing of the inkjet head is xml / min, x ≦ It is preferable to satisfy the relationship of y.

In the ink supply method according to another aspect of the present invention, it is preferable that the ink feeding speed in the replenishment step is controlled during printing by the ink jet head.

In the ink supply method according to another aspect of the present invention, it is preferable that the liquid supply speed in the supply process during the replenishment process is slower than the ink supply speed in the supply process during the non-replenishment circulation.

According to the ink supply method of the present invention, the same effects as those of the ink supply device described above can be obtained.

According to the ink supply device, the ink supply method, and the ink jet recording apparatus of the present invention, when the ink is replenished from the main tank to the ink tank, the liquid feeding speed of the ink flowing through the replenishment flow path is set at the time of non-replenishment circulation of the circulation flow path. The speed at which the ink passes through the deaeration module can be reduced by making it slower than the liquid feeding speed. Therefore, the ink replenished from the main tank can be sufficiently deaerated, and sufficient deaeration can be performed by passing the deaeration module once. Further, by providing a degassing module in the circulation channel, both the ink at the time of circulation and the ink at the time of replenishment can be degassed, so that the cost can be reduced and the apparatus can be downsized.

It is a block diagram of an ink supply apparatus. It is a block diagram which shows the structure of the supply control part of an ink supply apparatus. It is a flowchart which shows the ink supply method of an ink supply apparatus. 1 is a configuration diagram illustrating an overall configuration of an inkjet recording apparatus. It is a schematic block diagram of an inkjet head. It is a top view which shows the nozzle arrangement | sequence of a head module. It is sectional drawing which shows the three-dimensional structure of a droplet discharge element.

Hereinafter, preferred embodiments of the present invention will be described with reference to the accompanying drawings.

[Outline of ink supply device]
(overall structure)
FIG. 1 is a configuration diagram of an ink supply apparatus according to the present embodiment. An ink supply apparatus 100 shown in FIG. 1 supplies ink from an ink tank 52 that stores ink to an inkjet head 50 (hereinafter simply referred to as “head 50”) that is an ink supply target. In this device, the ink is circulated between the ink tank 52 and the head 50 by collecting the ink to the ink. Further, the ink supply apparatus 100 removes bubbles and dissolved gas from the ink circulated by the deaeration module 160. By circulating the ink in this way, clogging of ink inside the head 50 and mixing of bubbles are prevented.

As shown in FIG. 1, the ink supply apparatus 100 includes a supply flow path 12, a supply sub tank 18, a supply pump (supply means) 20, an ink tank 52, a supply side manifold 54, a main tank 56, a recovery flow path 112, and a recovery sub tank. 118, a recovery pump (recovery means) 120, a recovery side manifold 154, a deaeration module 160, a replenishment pump (replenishment means) 182, a vacuum pump 312, a replenishment flow path 316, and the like.

The supply flow path 12 is provided with a supply flow path pressure sensor 16 that converts the internal pressure of the supply flow path 12 into an electrical signal and outputs it, and the recovery flow path 112 converts the internal pressure of the recovery flow path 112 into an electrical signal. A recovery flow path pressure sensor 116 for converting and outputting is provided. As the supply flow path pressure sensor 16 and the recovery flow path pressure sensor 116, a sensor such as a semiconductor piezoresistive method, a capacitance method, or a silicon resonant method can be applied.

Further, a supply subtank 18 is provided in the supply flow path 12, and a recovery subtank 118 is provided in the recovery flow path 112. The supply sub tank 18 communicates with the ink tank 52 via the supply pump 20, and the recovery sub tank 118 communicates with the ink tank 52 via the recovery pump 120.

The head 50 has a structure in which n head modules 51-1, 51-2,..., 51-n are connected, and each head module 51-1, 51-2,. , 15-n to which ink is supplied, and discharge ports 115-1, 115-2,..., 115-n from which ink is discharged.

The head modules 51-1, 51-2,..., 51-n have supply ports 15-1, 15-2,. , 115-n are collected via the collection valves 114-1, 114-2,..., 114-n. The flow path 112 is in communication. As the supply valve 14 and the recovery valve 114, a normally open type (or latch type) electromagnetic valve whose opening / closing is controlled by a control signal is applied.

The supply side manifold 54 and the recovery side manifold 154 are temporary storage units for ink provided between the supply flow path 12 and the recovery flow path 112 and the head 50. The supply side manifold 54 and the recovery side manifold 154 are communicated with each other by

bypass passages

190 and 192, and the

bypass passages

190 and 192 are provided with

bypass passage valves

194 and 196, respectively.

A tube pump is applied to the supply pump 20 and the recovery pump 120. The supply pump 20 controls the pressure (liquid feeding amount) of the supply channel 12 that supplies ink from the ink tank 52 to the head 50, and the recovery pump 120 recovers the ink from the head 50 to the ink tank 52. To control the pressure (liquid feeding amount). A pump having the same performance (capacity) can be applied to the supply pump 20 and the recovery pump 120.

The supply pump 20 and the recovery pump 120 rotate only in one direction while the head 50 stops operating (that is, the period when ink flows stably). Further, when the internal pressure decreases during the period in which the head 50 is performing the discharge operation, the supply pump 20 increases the rotation speed, and the recovery pump 120 reverses to increase the internal pressure of the head 50.

That is, a predetermined back pressure (negative pressure) is applied to the ink inside the nozzles of the head 50 so that the internal pressure of the supply flow path 12 is relatively higher than the internal pressure of the recovery flow path 112. In addition, the driving of the supply pump 20 and the recovery pump 120 is controlled.

Further, the ink supply device 100 includes a pressure buffer unit including the supply sub tank 18 and an air tank 36 configured to be able to communicate with the air chamber 26 of the supply sub tank 18.

The supply sub-tank 18 has a structure partitioned into a liquid chamber 24 and an air chamber 26 by a flexible elastic film (flexible film) 22, and an ink outlet 24 A of the liquid chamber 24 includes a supply-side manifold 54 and a supply. The ink inlet 24 B communicates with the ink tank 52 via the supply pump 20. Further, the bubble outlet 27 of the liquid chamber 24 communicates with the ink tank 52 via the drain channel 28 and the drain valve 30.

When ink flows into the liquid chamber 24 from the ink inflow port 24B, the elastic film 22 is deformed to the air chamber 26 side according to the volume of the ink that has flowed in. On the other hand, since the volume of the ink flowing out from the ink outlet 24A does not fluctuate, even if the pressure fluctuation occurs in the supply flow path 12, the pressure fluctuation is suppressed by the action of the supply sub tank 18. That is, the supply sub-tank 18 has a pressure buffering function that suppresses fluctuations in the internal pressure of the supply flow path 12 due to fluctuations in the internal pressure of the head 50 and pulsating flow due to the operation of the supply pump 20.

The drain channel 28 is a channel for forcibly discharging the liquid in the liquid chamber 24. The drain channel 28 communicates with the liquid chamber 24 via the bubble discharge port 27, and when the drain valve 30 is opened, the liquid chamber 24. The ink inside is sent to the ink tank 52.

The air chamber 26 communicates with an air tank 36 via an air flow path 32 and an air connect valve 34, and the air tank 36 is configured to communicate with the atmosphere via an air valve 40 provided in an air communication path 38. That is, the air chamber 26 can be communicated with the air tank 36 by opening the air connect valve 34, and the volume of the air chamber 26 can be increased according to the pressure control of the ink feeding liquid. Furthermore, the air tank 36 and the air chamber 26 can be communicated with the atmosphere by opening the air valve 40.

A normally open type electromagnetic valve is applied to the air connect valve 34, and a normally closed type electromagnetic valve is applied to the air valve 40, so that ink does not leak from the head 50 even when the power is shut off when the emergency stop function is activated. It is configured.

The pressure buffer on the recovery side has the same structure as the pressure buffer on the supply side. That is, the ink supply apparatus 100 includes a recovery sub tank 118, a drain valve 130, an air flow path 132, an air connect valve 134, an air tank 136, an atmospheric communication path 138, and an air valve 140, which are the supply sub tank 18 and the drain valve 30, respectively. The air flow path 32, the air connect valve 34, the air tank 36, the atmosphere communication path 38, and the air valve 40 have the same structure.

The recovery sub-tank 118 is partitioned into a liquid chamber 124 and an air chamber 126 by an elastic film 122, and an ink inlet 124B of the liquid chamber 124 communicates with the ink tank 52 via the recovery pump 120 and the deaeration module 160, and the ink flow The outlet 124 A communicates with the head 50 through the recovery side manifold 154 and the recovery valve 114. Further, the bubble outlet 127 of the liquid chamber 124 communicates with the ink tank 52 via the drain flow path 128 and the drain valve 130.

The air chamber 126 communicates with the air tank 136 via the air flow path 132 and the air connect valve 134, and the air tank 136 is configured to communicate with the atmosphere via the air valve 140 provided in the atmosphere communication path 138. .

Furthermore, the ink supply device 100 is provided with a one-way valve 162 between the ink tank 52 and the supply pump 20 for preventing back flow of ink.

A vacuum pump 312 is connected to the deaeration module 160 via a strainer 310, and a sensor 314 is provided between the strainer 310 and the vacuum pump 312.

The degassing module 160 (an example of degassing means) is hollow by passing ink through one side of a hollow fiber membrane having a characteristic of allowing gas to permeate but not liquid and sucking the other side by a vacuum pump 312. The dissolved gas in the ink is removed in the process of the ink passing through the thread film. The foreign matter sucked from the vacuum pump 312 from the deaeration module 160 is captured by the strainer 310.

The sensor 314 is a sensor that measures the degree of vacuum in the vacuum pump 312, and may control the vacuum pump 312 according to the output value of the sensor 314.

Further, a filter 164 and a heat exchanger (cooling heating device) 166 are provided between the supply pump 20 and the supply sub tank 18. The heat exchanger 166 is provided with an ink temperature controller 320, and the ink temperature is adjusted to a desired temperature by flowing the ink through the heat exchanger 166 set to a predetermined temperature by the ink temperature controller 320. Is done. The heat exchanger 166 and the ink temperature controller 320 can be used in common for each ink of the inkjet head.

With such a configuration, the foreign matter is removed from the ink sent out from the ink tank 52 by the filter 164, the temperature is adjusted by the heat exchanger 166, and then sent to the supply sub tank 18.

In addition, a one-way valve 170 is provided between the recovery pump 120 and the ink tank 52 to prevent the backflow of ink, and a filter 172 is provided so that ink is sent from the ink tank 52 to the recovery sub tank 118. In addition, a predetermined filtering process is performed.

The ink supply device 100 is provided with safety valves (relief valves) 174 and 176, and an abnormality occurs in the supply pump 20 and the recovery pump 120, so that the internal pressure of the supply flow path 12 and the recovery flow path 112 is higher than a predetermined value. When it rises, the

safety valves

174 and 176 operate to lower the internal pressure of the supply flow path 12 and the recovery flow path 112. In addition, one-way valves 178 and 180 are provided for preventing the back flow of ink when the supply pump 20 and the recovery pump 120 are operated in reverse.

The main tank 56 stores ink for replenishing the circulation channel 300 including the ink tank 52, the supply channel 12, the supply side manifold 54, the head 50, the recovery side manifold 154, and the recovery channel 112. The main tank 56 communicates with the circulation flow path 300 at the junction 302 with the recovery flow path 112 via the replenishment flow path 316.

The deaeration module 160 is provided between the junction 302 and the ink tank 52, and the ink sent from the main tank 56 to the ink tank 52 is deaerated by the deaeration module 160. Since the deaeration module 160 is provided in the common flow path 117 of the recovery flow path 112 and the replenishment flow path 316, both the circulating ink and the replenishment ink can be degassed by one deaeration module 160. Cost reduction and downsizing of the apparatus can be implemented.

The replenishing flow path 316 is made of, for example, polyethylene, and is provided with a filter 184 and a replenishing pump 182 in order from the main tank 56 side toward the confluence point 302.

A tube pump is used as the replenishing pump 182. When the amount of ink in the ink tank 52 decreases, the replenishment pump 182 operates. The replenishment pump 182 sends the ink in the main tank 56 to the circulation channel 300 through the filter 184. Foreign matter is removed from the ink sent from the main tank 56 by the filter 184.

The ink sent to the circulation flow path 300 joins the ink sent through the recovery flow path 112 by the recovery pump 120 at the confluence 302, and goes to the ink tank 52 via the recovery flow path 112 (common flow path 117). Sent.

(Explanation of circulation)
The ink supply device 100 configured as described above operates the supply pump 20 and the recovery pump 120 to provide a differential pressure between the supply-side manifold 54 and the recovery-side manifold 154, so that the inside of the circulation channel 300 Circulate ink. For example, with the supply valve 14 and the recovery valve 114 open, the supply pump 20 is rotated forward to generate negative pressure in the supply-side manifold 54, while the recovery pump 120 is operated in reverse to move to the recovery-side manifold 154. When a negative pressure lower than the supply side is generated, the ink supplied from the ink tank 52 to the supply side manifold 54 via the supply subtank 18 flows to the recovery side manifold 154 via the head 50, and further, the recovery flow path 112, The ink can be circulated back to the ink tank 52 via the recovery sub tank 118 or the like.

When the ink is circulated, the second bypass passage valve 196 provided in the second bypass passage 192 is opened, and the supply side manifold 54 and the recovery side manifold 154 are connected via the second bypass passage 192. It is good to communicate. It should be noted that any one of the

bypass channels

190 and 192 may be provided as long as it has a diameter that does not cause pressure loss during pressurization.

(Supply control unit)
FIG. 2 is a block diagram illustrating a configuration of the supply control unit 322 of the ink supply apparatus 100 according to the present embodiment. In FIG. 2, only control of the pump is described, and control of the head 50 and each valve is omitted.

The ink supply device 100 includes a supply control unit 322 and a memory 324.

The supply control unit 322 functions as a control unit that performs overall control of the operation of the entire ink supply apparatus 100, and operates / inoperates the supply pump 20, the recovery pump 120, and the replenishment pump 182 according to a predetermined control program, the liquid feeding speed, And control the amount of liquid delivered. The memory 324 is a storage unit that stores the control program of the supply control unit 322 and various parameters.

[Operation of ink supply device]
FIG. 3 is a flowchart illustrating an ink supply method of the ink supply apparatus 100.

(Step S101)
The ink supply device 100 starts to circulate ink when the power is turned on. That is, the supply control unit 322 controls the supply pump 20 to supply ink from the ink tank 52 to the head 50 via the supply flow path 12 and the supply side manifold 54 (supply process), and at the same time, the recovery pump 120 The ink is recovered from the head 50 via the recovery side manifold 154 and the recovery flow path 112 (recovery process), and the ink is circulated in the circulation flow path 300 (circulation process).

At this time, gas is removed from the ink circulating through the circulation channel 300 by the deaeration module 160 (deaeration step). It takes several minutes from the start of ink circulation until ink can be printed, due to deaeration of ink and temperature control. After the ink is deaerated and temperature-controlled, image formation is started.

(Step S102)
Since the ink in the ink tank 52 is reduced by performing image formation, it is determined whether or not it is necessary to replenish the ink into the ink tank 52. If it is necessary to replenish ink, the process proceeds to step S103. If it is not necessary to replenish ink, the process proceeds to step S106. Whether or not the ink in the ink tank 52 needs to be replenished can be determined by detecting the liquid level with a liquid level sensor (not shown) provided in the ink tank 52.

(Step S103)
When it is necessary to replenish ink, the replenishment pump 182 is operated, and ink is supplied from the main tank 56 to the ink tank 52 via the replenishment flow path 316, the recovery flow path 112 (common flow path 117), and the deaeration module 160. Replenish.

At this time, the liquid feeding speed of the replenishment pump 182 is made slower than the liquid feeding speed of the recovery pump 120 during the circulation and non-replenishment circulation during the discharge performed in step S101. By slowing the liquid feeding speed of the replenishment pump 182, when ink is replenished from the main tank 56 to the ink tank 52, the time for ink to pass through the deaeration module 160 can be delayed. Deaeration can be sufficiently performed (deaeration step).

Also, when the ink is replenished, the liquid feed speed of the recovery pump 120 is also lowered in order to make the liquid feed speed of the replenishment pump slower than the liquid feed speed of the recovery pump during non-replenishment circulation. Therefore, in order to control the back pressure of the head 50, the liquid feeding speed of the supply pump 20 is also controlled.

The amount of ink replenished from the main tank 56 to the ink tank 52 has a relationship of x ≦ y where the amount of ink used for printing is xml / min and the replenishment flow rate of ink to be replenished is ym / min. It is preferable to adjust the amount of ink to be replenished so as to satisfy.

During non-replenishment circulation, since the ink circulates in the circulation channel 300, the deaeration can be sufficiently performed by the ink passing through the deaeration module 160 a plurality of times. Ink replenishment from the main tank 56 to the ink tank 52 (circulation flow path 300) passes through the deaeration module 160 once during printing, so that the ink reaches the head 50. It is necessary to do. Since the ink passing speed of the degassing module 160 is slowed by slowing the liquid supply speed of the replenishing ink by the replenishing pump 182, the ink can be sufficiently degassed with a single ink passage. Therefore, even if ink is replenished from the main tank 56 to the circulation channel 300 during printing, the ink can be sufficiently deaerated.

The liquid feed flow rate of the recovery pump 120 during non-replenishment circulation is preferably 6 ml / sec or more and 10 ml / sec or less. When ink is replenished by the replenishment pump 182, the liquid feed flow rate of the replenishment pump 182 is set to the non-replenishment circulation. It is preferably 3 ml / sec or more and 5 mlm / sec or less later than the liquid feed flow rate of the recovery pump 120 at the time. Further, when ink is replenished by the replenishment pump 182, the flow rate of the collection pump 120 in the circulation flow path is preferably 3 ml / sec or more and 5 ml / sec or less, and preferably the same as the flow rate of the replenishment pump 182. . The smaller the ink replenishment flow rate, the better the deaeration of ink in the deaeration module 160, which is preferable. However, if the flow rate of the recovery pump 120 is decreased in accordance with the replenishment pump 182, the ink cannot be recovered in time in the circulation flow path 300. Therefore, the lower limit of the flow rate is the condition of the flow rate in the circulation flow path 300 and the inkjet head 50. It is necessary to determine it according to the back pressure conditions.

After completion of ink replenishment from the main tank 56 to the ink tank 52, the process proceeds to step S104.

(Step S104)
It is determined whether or not the ink in the circulation channel 300 has been replenished. When the ink supply is completed, the process proceeds to step S105. If ink replenishment has not been completed, ink is replenished from the main tank 56 to the supply channel until replenishment is completed. Whether or not ink replenishment is completed is determined by detecting a liquid level using a liquid level sensor (not shown) provided in the ink tank 52, as in step S102. Can be judged.

(Step S105)
When the replenishment of ink from the main tank 56 to the circulation channel 300 is completed, the liquid feed speed of the recovery pump 120 is returned to the liquid feed speed at the time of non-replenishment circulation, and the replenishment pump 182 is stopped, End ink replenishment and return to the non-replenishment circulation state.

(Step S106)
It is determined whether or not to end the operation of the ink supply apparatus 100. For example, when the power supply of the ink supply apparatus 100 is shut off, the operation is terminated. If the operation is not terminated, the process returns to step S102 and the same processing is repeated.

As described above, according to the present embodiment, when ink is replenished from the main tank 56 to the ink tank 52, the ink is once passed through the deaeration module 160 by reducing the liquid feeding speed of the replenishment pump 182. Ink can be sufficiently deaerated and the dissolved oxygen concentration in the ink tank 52 can be prevented from increasing.

[Examples of application to inkjet recording devices]
Next, as an application example of the ink supply apparatus described above, an ink jet recording apparatus in which the ink supply apparatus 100 described above is applied to an ink supply unit of an ink jet head will be described.

(Overall configuration of inkjet recording apparatus)
FIG. 4 is a configuration diagram showing the overall configuration of the ink jet recording apparatus including the liquid supply apparatus according to the embodiment of the present invention. The ink jet recording apparatus 200 shown in the figure forms an image on a recording surface of a recording medium 214 based on predetermined image data using an ink containing a color material and an aggregating treatment liquid having a function of aggregating the ink. This is a two-liquid aggregation type recording apparatus.

The inkjet recording apparatus 200 mainly includes a paper feeding unit 220, a processing liquid application unit 230, a drawing unit 240, a drying processing unit 250, a fixing processing unit 260, and a discharge unit 270. In addition, an ink supply device 100 that supplies ink to the drawing unit 240 is provided.

At the same time as

transfer cylinders

232, 242, 252, and 262 are provided as means for delivering the recording medium 214 conveyed upstream of the processing liquid application unit 230, the drawing unit 240, the drying processing unit 250, and the fixing processing unit 260. As the means for conveying the recording medium 214 while holding the processing liquid application unit 230, the drawing unit 240, the drying processing unit 250, and the fixing processing unit 260, the

impression cylinders

234, 244, 254, and 264 having a drum shape are used. Is provided.

The transfer cylinders 232 to 262 and the impression cylinders 234 to 264 are provided with grippers 280A and 280B that hold the leading end portion of the recording medium 214 at predetermined positions on the outer peripheral surface. The structure in which the gripper 280A and the gripper 280B sandwich and hold the leading end portion of the recording medium 214 and the structure in which the recording medium 214 is transferred between the gripper provided in another impression cylinder or the transfer cylinder are the same, and The gripper 280 A and the gripper 280 B are arranged at symmetrical positions moved by 180 ° in the rotation direction of the pressure drum 234 on the outer peripheral surface of the pressure drum 234.

When the transfer cylinders 232 to 262 and the impression cylinders 234 to 264 are rotated in a predetermined direction with the gripper 280A and 280B holding the leading end portion of the recording medium 214, the transfer cylinders 232 to 262 and the impression cylinders 234 to 264 are rotated. The recording medium 214 is rotated and conveyed along the outer peripheral surface.

In FIG. 4, only the grippers 280 A and 280 B provided on the impression cylinder 234 are denoted by reference numerals, and the other impression cylinders and the transfer cylinder grippers are omitted.

When the recording medium (sheet) 214 accommodated in the paper supply unit 220 is fed to the treatment liquid application unit 230, the aggregation process is performed on the recording surface of the recording medium 214 held on the outer peripheral surface of the impression cylinder 234. A liquid (hereinafter simply referred to as “treatment liquid”) is applied. The “recording surface of the recording medium 214” is an outer surface in a state where the pressure drums 234 to 264 are held, and is a surface opposite to a surface held by the pressure drums 234 to 264.

Thereafter, the recording medium 214 to which the aggregating treatment liquid is applied is sent to the drawing unit 240, and the drawing unit 240 applies the color ink to the area to which the aggregating treatment liquid is applied to form a desired image.

Further, the recording medium 214 on which the image of the color ink is formed is sent to the drying processing unit 250, where the drying processing unit 250 performs drying processing, and after the drying processing, the recording medium 214 is sent to the fixing processing unit 260 to perform fixing processing. Is done. By performing the drying process and the fixing process, the image formed on the recording medium 214 is fastened. In this manner, a desired image is formed on the recording surface of the recording medium 214, and after the image is fixed on the recording surface of the recording medium 214, the image is conveyed from the discharge unit 270 to the outside of the apparatus.

Hereinafter, each unit (the paper feeding unit 220, the processing liquid coating unit 230, the drawing unit 240, the drying processing unit 250, the fixing processing unit 260, and the discharge unit 270) of the ink jet recording apparatus 200 will be described in detail.

(Paper Feeder)
The paper feeding unit 220 is provided with a paper feeding tray 222 and a feeding mechanism (not shown), and the recording medium 214 is configured to be fed one by one from the paper feeding tray 222. The recording medium 214 sent out from the paper feed tray 222 is positioned by a guide member (not shown) so as to be positioned at a gripper (not shown) of the transfer drum (paper feed drum) 232 and temporarily stops. A gripper (not shown) holds the leading end portion of the recording medium 214, and transfers the recording medium 214 to and from the gripper provided in the processing liquid cylinder 234.

(Processing liquid application part)
The processing liquid coating unit 230 includes a processing liquid drum (processing liquid drum) 234 that holds the recording medium 214 delivered from the paper feed cylinder 232 on the outer peripheral surface and transports the recording medium 214 in a predetermined transport direction, and a processing liquid. And a treatment liquid application unit 230 that applies a treatment liquid to the recording surface of the recording medium 214 held on the outer peripheral surface of the cylinder 234. When the processing liquid cylinder 234 is rotated counterclockwise in FIG. 4, the recording medium 214 is rotated and conveyed in the counterclockwise direction along the outer peripheral surface of the processing liquid cylinder 234.

4 is provided at a position facing the outer peripheral surface (recording medium holding surface) of the processing liquid cylinder 234. The processing liquid application unit 230 shown in FIG. As a configuration example of the processing liquid application unit 230, a processing liquid container in which the processing liquid is stored, a pumping roller that is partially immersed in the processing liquid in the processing liquid container, and pumps up the processing liquid in the processing liquid container, and a pumping roller An embodiment including an application roller (rubber roller) that moves the pumped processing liquid onto the recording medium 214 is exemplified.

Note that an application roller moving mechanism for moving the application roller in the vertical direction (the normal direction of the outer peripheral surface of the processing liquid cylinder 234) is provided, and the processing liquid is not applied to portions other than the recording medium 214. Is preferred. The grippers 280A and 280B that sandwich the leading end of the recording medium 214 are arranged so as not to protrude from the peripheral surface.

The treatment liquid applied to the recording medium 214 by the treatment liquid application unit 230 contains a color material aggregating agent that aggregates the color material (pigment) in the ink applied by the drawing unit 240, and the treatment liquid is applied on the recording medium 214. And the ink come into contact with each other, the separation of the color material and the solvent in the ink is promoted.

The treatment liquid application unit 230 is preferably applied while measuring the amount of the treatment liquid applied to the recording medium 214, and the film thickness of the treatment liquid on the recording medium 214 is determined by the ink droplets ejected from the drawing unit 240. It is preferable to make it sufficiently smaller than the diameter.

(Drawing part)
The drawing unit 240 holds a recording medium 214 and conveys the drawing cylinder (drawing drum) 244, a sheet pressing roller 246 for bringing the recording medium 214 into close contact with the drawing cylinder 244, and an ink jet for applying ink to the recording medium 214.

Heads

248M, 248K, 248C, and 248Y are provided. The basic structure of the drawing cylinder 244 is common to the processing liquid cylinder 234 described above.

The sheet pressing roller 246 is a guide member for bringing the recording medium 214 into close contact with the outer peripheral surface of the drawing cylinder 244, faces the outer peripheral surface of the drawing cylinder 244, and delivers the recording medium 214 between the transfer cylinder 242 and the drawing cylinder 244. It is located downstream of the position in the conveyance direction of the recording medium 214 and upstream of the inkjet heads 248M, 248K, 248C, and 248Y in the conveyance direction of the recording medium 214.

Further, a paper floating detection sensor (not shown) is disposed between the paper pressing roller 246 and the most upstream ink jet head 248Y in the conveyance direction of the recording medium 214. The sheet floating detection sensor detects the amount of floating immediately before the recording medium 214 enters immediately below the inkjet heads 248M, 248K, 248C, and 248Y. In the case where the floating amount of the recording medium 214 detected by the paper floating detection sensor exceeds a predetermined threshold, the inkjet recording apparatus 200 shown in this example notifies that fact and interrupts the conveyance of the recording medium 214. It is configured as follows.

The recording medium 214 transferred from the transfer cylinder 242 to the drawing cylinder 244 is pressed by the sheet pressing roller 246 when being rotated and conveyed with the front end held by a gripper (not shown), and the outer periphery of the drawing cylinder 244 Adhere to the surface. In this way, after the recording medium 214 is brought into close contact with the outer peripheral surface of the drawing cylinder 244, the recording medium 214 is not lifted from the outer peripheral surface of the drawing cylinder 244, and is printed in the print area immediately below the inkjet heads 248M, 248K, 248C, and 248Y. Sent.

The inkjet heads 248M, 248K, 248C, and 248Y correspond to four colors of ink, magenta (M), black (K), cyan (C), and yellow (Y), respectively, and the rotation direction of the drawing cylinder 244 Recording is performed on the recording medium 214 in which the ink ejection surfaces (nozzle surfaces) of the inkjet heads 248M, 248K, 248C, and 248Y are held in the drawing cylinder 244 in order from the upstream side (counterclockwise direction in FIG. 4). It arrange | positions so that a surface may be opposed. The “ink ejection surface (nozzle surface)” is a surface of the inkjet heads 248M, 248K, 248C, and 248Y that faces the recording surface of the recording medium 214, and is a nozzle that ejects ink (described later in FIG. 6). It is a surface on which a reference numeral 408 is attached).

In addition, the inkjet heads 248M, 248K, 248C, and 248Y shown in FIG. 4 have substantially the same recording surface of the recording medium 214 held on the outer peripheral surface of the drawing cylinder 244 and the nozzle surfaces of the inkjet heads 248M, 248K, 248C, and 248Y. It is inclined with respect to the horizontal plane so as to be parallel.

The inkjet heads 248M, 248K, 248C, and 248Y are full-line heads having a length corresponding to the maximum width of the image forming area in the recording medium 214 (the length in the direction orthogonal to the conveyance direction of the recording medium 214). And fixedly installed so as to extend in a direction perpendicular to the conveyance direction of the recording medium 214.

Ink jet heads 248M, 248K, 248C, and 248Y are supplied with ink from

ink supply devices

100M, 100K, 100C, and 100Y, respectively. Each of the

ink supply devices

100M, 100K, 100C, and 100Y has the same configuration as the ink supply device 100 shown in FIG. The strainer 310, the vacuum pump 312, the sensor 314, and the ink temperature controller 320 can be used in common in the

ink supply devices

100M, 100K, 100C, and 100Y (FIG. 1).

On the nozzle surfaces (liquid ejection surfaces) of the inkjet heads 248M, 248K, 248C, and 248Y, ink ejection nozzles are formed in a matrix arrangement over the entire width of the image forming area of the recording medium 214.

When the recording medium 214 is conveyed to a printing area immediately below the inkjet heads 248M, 248K, 248C, and 248Y, an image is applied to the area where the aggregation processing liquid of the recording medium 214 is applied from the inkjet heads 248M, 248K, 248C, and 248Y. Based on the data, ink of each color is ejected (droplet ejection).

When the droplets of the corresponding color ink are ejected from the inkjet heads 248M, 248K, 248C, and 248Y toward the recording surface of the recording medium 214 held on the outer peripheral surface of the drawing cylinder 244, the recording medium 214 When the treatment liquid and the ink come into contact with each other, an agglomeration reaction of the color material (pigment-based color material) dispersed in the ink or the color material (dye-based color material) to be insolubilized appears, and a color material aggregate is formed. Thereby, the movement of the color material (dot misalignment and dot color unevenness) in the image formed on the recording medium 214 is prevented.

In addition, since the drawing cylinder 244 of the drawing unit 240 is structurally separated from the processing liquid cylinder 234 of the processing liquid application unit 230, the processing liquid may adhere to the inkjet heads 248M, 248K, 248C, and 248Y. Therefore, the cause of abnormal ink ejection can be reduced.

In this example, the configuration of the standard colors (4 colors) of MKCY is illustrated, but the combination of ink colors and the number of colors is not limited to this embodiment, and light ink, dark ink, and special ink are used as necessary. Color ink may be added. For example, it is possible to add an inkjet head that discharges light-colored ink such as light cyan and light magenta, and the arrangement order of the color heads is not particularly limited.

(Dry processing part)
The drying processing unit 250 holds a drying drum (drying drum) 254 that holds and conveys the recording medium 214 after image formation, and a drying processing device 256 that performs a drying process for evaporating moisture (liquid component) on the recording medium 214. It has. The basic structure of the drying cylinder 254 is the same as that of the processing liquid cylinder 234 and the drawing cylinder 244 described above, and a description thereof is omitted here.

The drying processing device 256 is a processing unit that is disposed at a position facing the outer peripheral surface of the drying drum 254 and evaporates moisture present in the recording medium 214. When ink is applied to the recording medium 214 by the drawing unit 240, the liquid component (solvent component) of the ink and the liquid component (solvent component) of the processing liquid separated by the aggregation reaction between the processing liquid and the ink are placed on the recording medium 214. Since it remains, it is necessary to remove such a liquid component.

The drying processing device 256 performs a drying process for evaporating a liquid component existing on the recording medium 214 by heating with a heater, blowing with a fan, or a combination thereof, and a process for removing the liquid component on the recording medium 214. Part. The amount of heating and the amount of air supplied to the recording medium 214 are appropriately set according to parameters such as the amount of moisture remaining on the recording medium 214, the type of the recording medium 214, and the conveyance speed (drying processing time) of the recording medium 214. Is done.

When the drying processing by the drying processing device 256 is performed, the drying cylinder 254 of the drying processing unit 250 is structurally separated from the drawing cylinder 244 of the drawing unit 240, so that the inkjet heads 248M, 248K, 248C, and In 248Y, it is possible to reduce the cause of abnormal ink ejection due to drying of the head meniscus by heat or air blowing.

In order to exert the cockling correction effect of the recording medium 214, the curvature of the drying cylinder 254 is preferably 0.002 (1 / mm) or more. In order to prevent the recording medium from being curved (curled) after the drying process, the curvature of the drying cylinder 254 is preferably 0.0033 (1 / mm) or less.

Also, a means for adjusting the surface temperature of the drying cylinder 254 (for example, a built-in heater) may be provided, and the surface temperature may be adjusted to 50 ° C. or higher. By performing heat treatment from the back surface of the recording medium 214, drying is promoted, and image destruction during the subsequent fixing process is prevented. In this embodiment, it is more effective to provide means for bringing the recording medium 214 into close contact with the outer peripheral surface of the drying drum 254. As an example of means for closely attaching the recording medium 214, vacuum adsorption, electrostatic adsorption, and the like can be given.

The upper limit of the surface temperature of the drying cylinder 254 is not particularly limited, but from the viewpoint of safety of maintenance work (such as prevention of burns due to high temperatures) such as cleaning of ink adhering to the surface of the drying cylinder 254. It is preferably set to 75 ° C. or lower (more preferably 60 ° C. or lower).

The drying drum 254 configured in this manner is held on the outer peripheral surface of the recording medium 214 so that the recording surface of the recording medium 214 faces outward (that is, in a state where the recording surface of the recording medium 214 is convex). By performing the drying process while rotating and transporting, drying unevenness due to wrinkling and floating of the recording medium 214 is surely prevented.

(Fixing processing part)
The fixing processing unit 260 includes a fixing drum (fixing drum) 264 that holds and conveys the recording medium 214, a heater 266 that performs heat treatment on the recording medium 214 on which an image is formed and liquid is removed, and the recording And a fixing roller 268 that presses the medium 214 from the recording surface side. The basic structure of the fixing cylinder 264 is the same as that of the processing liquid cylinder 234, the drawing cylinder 244, and the drying cylinder 254, and a description thereof is omitted here. The heater 266 and the fixing roller 268 are disposed at positions facing the outer peripheral surface of the fixing cylinder 264, and are sequentially disposed from the upstream side in the rotation direction of the fixing cylinder 264 (counterclockwise direction in FIG. 4).

In the fixing processing unit 260, the recording surface of the recording medium 214 is subjected to preheating processing by the heater 266 and fixing processing by the fixing roller 268. The heating temperature of the heater 266 is appropriately set according to the type of recording medium, the type of ink (the type of polymer fine particles contained in the ink), and the like. For example, a mode in which the glass transition temperature and the minimum film forming temperature of the polymer fine particles contained in the ink are considered.

The fixing roller 268 is a roller member that heats and presses the dried ink to weld the self-dispersing polymer fine particles in the ink to form a film of the ink, and is configured to heat and press the recording medium 214. The Specifically, the fixing roller 268 is disposed so as to be in pressure contact with the fixing cylinder 264 and constitutes a nip roller with the fixing cylinder 264. As a result, the recording medium 214 is sandwiched between the fixing roller 268 and the fixing cylinder 264, and is nipped with a predetermined nip pressure, and fixing processing is performed.

As an example of the configuration of the fixing roller 268, there is an embodiment in which the fixing roller 268 is configured by a heating roller in which a halogen lamp is incorporated in a metal pipe such as aluminum having good thermal conductivity. By heating the recording medium 214 with such a heating roller, when thermal energy equal to or higher than the glass transition temperature of the polymer fine particles contained in the ink is applied, the polymer fine particles melt to form a transparent film on the surface of the image. Is done.

When pressure is applied to the recording surface of the recording medium 214 in this state, when the polymer fine particles melted into the irregularities of the recording medium 214 are pressed and fixed, the irregularities on the image surface are leveled, and favorable glossiness can be obtained. A configuration in which a plurality of fixing rollers 268 are provided in accordance with the thickness of the image layer and the glass transition temperature characteristics of the polymer particles is also preferable.

The surface hardness of the fixing roller 268 is preferably 71 ° or less. By making the surface of the fixing roller 268 softer, a tracking effect can be expected with respect to the unevenness of the recording medium 214 caused by cockling, and fixing unevenness due to the unevenness of the recording medium 214 is more effectively prevented. .

4 is provided with an in-line sensor 282 at a stage subsequent to the processing region of the fixing processing unit 260 (on the downstream side in the recording medium conveyance direction). The inline sensor 282 is a sensor for reading an image formed on the recording medium 214 (or a check pattern formed in a blank area of the recording medium 214), and a CCD line sensor is preferably used.

In the ink jet recording apparatus 200 shown in this example, the presence or absence of ejection abnormality of the ink jet heads 248M, 248K, 248C, and 248Y is determined based on the reading result of the inline sensor 282. Further, the inline sensor 282 may include a measuring unit for measuring a moisture amount, a surface temperature, a glossiness, and the like. In such an embodiment, parameters such as the processing temperature of the drying processing unit 250, the heating temperature of the fixing processing unit 260, and the pressurizing pressure are appropriately adjusted based on the reading results of the moisture amount, the surface temperature, and the glossiness. The control parameters are appropriately adjusted in accordance with the temperature change and the temperature change of each part.

(Discharge part)
As shown in FIG. 4, a discharge unit 270 is provided following the fixing processing unit 260. The discharge unit 270 includes an endless transport chain 274 wound around the stretching

rollers

272A and 272B, and a discharge tray 276 that stores the recording medium 214 after image formation.

The recording medium 214 after the fixing process sent out from the fixing processing unit 260 is transported by the transport chain 274 and discharged to the discharge tray 276.

[Inkjet head structure]
Next, an example of the structure of the inkjet heads 248M, 248K, 248C, and 248Y provided in the drawing unit 240 will be described. Since the structures of the ink jet heads 248M, 248K, 248C, and 248Y corresponding to the respective colors are the same, the ink jet head (hereinafter also simply referred to as “head”) is denoted by reference numeral 400 below. Shall.

FIG. 5 is a schematic configuration diagram of the ink jet head 400, which is a view of the recording surface of the recording medium viewed from the ink jet head 400 (a plan perspective view of the head). The head 400 shown in the figure forms a multi-head by connecting n head modules 402-i (i is an integer from 1 to n) in a line along the longitudinal direction of the head 400. Each head module 402-i is supported by head covers 404 and 406 from both sides of the head 400 in the short direction. It is also possible to configure a multi-head by arranging the head modules 402 in a staggered manner.

As an application example of a multi-head composed of a plurality of sub-heads, there is a full-line head corresponding to the full width of the recording medium. The full-line head has a plurality of nozzles (FIG. 6) corresponding to the length (width) in the main scanning direction of the recording medium in the direction (main scanning direction) orthogonal to the moving direction (sub-scanning direction) of the recording medium. (Shown with reference numeral 408). An image can be formed on the entire surface of the recording medium by a so-called single pass image recording method in which the head 400 having such a structure and the recording medium are scanned only once relatively.

The head module 402-i constituting the head 400 has a substantially parallelogram-shaped planar shape, and an overlap portion is provided between adjacent sub-heads. The overlap portion is a connecting portion of the sub heads, and is formed by nozzles in which adjacent dots belong to different sub heads in the arrangement direction of the head modules 402-i. 5 is equivalent to the head 50 shown in FIG. 1, and the head module 402 is equivalent to the head module 51.

FIG. 6 is a plan view showing the nozzle arrangement of the head module 402-i. As shown in the figure, each head module 402-i has a structure in which nozzles 408 are two-dimensionally arranged, and a head including such a head module 402-i is a so-called matrix head. . The head module 402-i shown in FIG. 6 has a number of nozzles 408 along a column direction W that forms an angle α with respect to the sub-scanning direction Y and a row direction V that forms an angle β with respect to the main scanning direction X. It has an aligned structure, and the substantial nozzle arrangement density in the main scanning direction X is increased. In FIG. 6, the nozzle group (nozzle row) arranged along the row direction V is denoted by reference numeral 410, and the nozzle group (nozzle row) arranged along the column direction W is denoted by reference numeral 412. ing.

As another example of the matrix arrangement of the nozzles 408, there is a configuration in which a plurality of nozzles 408 are arranged along the row direction along the main scanning direction X and the column direction oblique to the main scanning direction X.

FIG. 7 is a cross-sectional view showing a three-dimensional configuration of one-channel droplet discharge elements (ink chamber units corresponding to one nozzle 408) serving as a recording element unit. As shown in the figure, the head 400 (head module 402) of this example includes a nozzle plate 414 in which nozzles 408 are formed, and a channel plate 420 in which channels such as a pressure chamber 416 and a common channel 418 are formed. It has a structure in which etc. are laminated and joined. The nozzle plate 414 constitutes the nozzle surface 414A of the head 400, and a plurality of nozzles 408 communicating with the pressure chambers 416 are two-dimensionally formed.

The flow path plate 420 forms a side wall portion of the pressure chamber 416 and forms a flow path forming a supply port 422 as a narrowed portion (most narrowed portion) of an individual supply path that guides ink from the common flow path 418 to the pressure chamber 416. It is a member. For convenience of explanation, the flow path plate 420 has a structure in which one or a plurality of substrates are stacked, although it is illustrated schematically in FIG.

The nozzle plate 414 and the flow path plate 420 can be processed into a required shape by a semiconductor manufacturing process using silicon as a material.

The common flow path 418 communicates with an ink tank (corresponding to the ink tank 52 shown in FIG. 1) serving as an ink supply source, and ink supplied from the ink tank is supplied to each pressure chamber 416 via the common flow path 418. The

A diaphragm 424 constituting a part of the pressure chamber 416 (the top surface in FIG. 7) includes an individual electrode 426 and a lower electrode 428, and the piezoelectric body 430 is sandwiched between the individual electrode 426 and the lower electrode 428. A piezoelectric actuator 432 having the above structure is joined. When the diaphragm 424 is formed of a metal thin film and a metal oxide film, it functions as a common electrode corresponding to the lower electrode 428 of the piezoelectric actuator 432. In the aspect in which the diaphragm is formed of a non-conductive material such as resin, a lower electrode layer made of a conductive material such as metal is formed on the surface of the diaphragm member.

By applying a driving voltage to the individual electrode 426, the piezo actuator 432 is deformed to change the volume of the pressure chamber 416, and ink is ejected from the nozzle 408 by the pressure change accompanying this. When the piezo actuator 432 returns to its original state after ink ejection, new ink is refilled into the pressure chamber 416 from the common channel 418 through the supply port 422.

As shown in FIG. 6, the ink chamber unit having such a structure is latticed in a fixed arrangement pattern along a row direction V that forms an angle β with the main scanning direction X and a column direction W that forms an angle α with respect to the sub-scanning direction Y. The high-density nozzle head of this example is realized by arranging a large number in the shape. In this matrix arrangement, when the interval between adjacent nozzles in the sub-scanning direction Y is Ls, in the main scanning direction X, each nozzle 408 is substantially equivalent to a linear arrangement with a constant pitch P = Ls / tan θ. Can be handled.

In this example, the piezo actuator 432 is applied as a means for generating ink ejection force to be ejected from the nozzles 408 provided in the head 400. However, a heater is provided in the pressure chamber 416, and the pressure of film boiling caused by heating of the heater is used. It is also possible to apply a thermal method that ejects ink.

In this specification, an inkjet recording apparatus that discharges colored ink suitable for graphic printing has been described as an example. However, a resist ink (heat-resistant coating material) for printed wiring and conductive fine particles are dispersed in a dispersion medium. The present invention can be applied to an image forming apparatus that ejects ink used for manufacturing a dispersion liquid and a color filter.

The technical scope of the present invention is not limited to the scope described in the above embodiment. The configurations and the like in the embodiments can be appropriately combined between the embodiments without departing from the gist of the present invention.

DESCRIPTION OF SYMBOLS 12 ... Supply flow path, 14 ... Supply valve, 15 ... Supply port, 18 ... Supply sub tank, 50, 400 ... Inkjet head, 51, 402 ... Head module, 52 ... Ink tank, 54 ... Supply side manifold, 56 ... Main tank , 100, 100M, 100K, 100C, 100Y ... ink supply device, 112 ... recovery flow path, 114 ... recovery valve, 115 ... discharge port, 118 ... recovery sub tank, 154 ... recovery side manifold, 160 ... deaeration module, 182 ... Replenishment pump, 200 ... inkjet recording apparatus, 300 ... circulation flow path, 302 ... confluence, 312 ... vacuum pump, 316 ... replenishment flow path, 322 ... supply control unit

Claims

Circulation including an ink tank for storing ink, an inkjet head, a supply channel for supplying ink from the ink tank to the inkjet head, and a recovery channel for recovering the ink from the inkjet head to the ink tank An ink supply device comprising a flow path,
A replenishment flow path connected to the recovery flow path;
A main tank that is connected to the replenishing flow path and stores the ink for replenishing the ink tank;
Provided between the ink tanks from the confluence of the recovery flow path and the replenishment flow path, and is common to the flow path at the time of ink recovery by the circulation flow path and the flow path at the time of ink replenishment by the replenishment flow path. Degassing means for degassing ink flowing through the common flow path portion,
The liquid feeding speed of the ink flowing through the replenishment flow path when replenishing the ink from the main tank to the ink tank is circulated in a state where the ink is not replenished from the main tank to the ink tank. A liquid feeding speed of the ink flowing through the recovery flow path at the time of non-replenishment circulation for circulating the ink through the flow path, and a flow speed of the ink flowing through the recovery flow path at the time of ink replenishment; An ink supply device configured to be slower than a liquid feeding speed of the ink flowing through the recovery flow path during the non-replenishment circulation;
The replenishment flow path includes a replenishment pump for feeding the ink,
The relation of x ≦ y is satisfied, where a replenishing flow rate of the ink fed by the replenishing pump is yml / min and a usage amount of the ink used for printing of the inkjet head is xml / min. Ink supply device.
The ink supply device according to claim 1 or 2, wherein the replenishment of the ink is performed at the time of printing by the inkjet head.
4. The method according to claim 1, wherein when the ink is replenished, a liquid feeding speed of the ink flowing through the supply channel is made slower than a liquid feeding speed of the ink flowing through the supply channel during the non-replenishment circulation. The ink supply device according to item.
An inkjet head having a supply port to which ink is supplied, a nozzle for discharging ink, and a discharge port for discharging ink that has not been discharged;
An ink supply device according to any one of claims 1 to 4,
An ink jet recording apparatus comprising:
A supply step of supplying ink from the ink tank to the inkjet head in a circulation flow path including an ink tank and an inkjet head, and a recovery step of collecting the ink from the inkjet head to the ink tank; A circulation step of circulating the ink with the ink supply method,
A replenishment step of replenishing the ink tank with the ink in the main tank via a replenishment flow path connecting the main tank storing the ink and the ink collection side of the circulation flow path;
A degassing step of degassing the ink recovered in the recovery step and the ink replenished in the replenishment step;
In the degassing step of degassing the ink in the replenishment step, the ink feed rate in the replenishment step is the same as the ink feed rate in the recovery step during non-replenishment circulation circulating in the circulation flow path. An ink supply method in which the liquid feeding speed of the recovery step is slower than the liquid feeding speed of the recovery step during the non-replenishment circulation.
The relationship of x ≦ y is satisfied, where a replenishing flow rate of the ink fed in the replenishing step is yml / min and a usage amount of the ink used for printing of the inkjet head is xml / min. The ink supply method according to claim.
The ink supply method according to claim 6 or 7, wherein the ink feeding speed in the replenishing step is controlled at the time of printing by the inkjet head.
The ink according to any one of claims 6 to 8, wherein a liquid feeding speed of the ink in the supplying process at the replenishing process is made slower than a liquid feeding speed of the ink in the supplying process at the non-replenishing circulation. Supply method.