Degassing device, ink jet recording device, degassing method, and program

Abstract

To provide a degassing device, an ink jet recording device, a degassing method, and a program capable of efficiently performing discharge control by suppressing atomization or backflow of ink components (monomers) generated from the interior of a degassing module.SOLUTION: A degassing device comprises: an external recirculation-type degassing module 451 which includes a gas permeation membrane (hollow fiber membrane 4512) capable of degassing dissolved gases in ink; a hollow fiber valve 4513c which is provided on the upstream side of the degassing module 451; and a control unit 50 which performs discharge control for discharging ink components that have permeated the gas permeation membrane. The control unit 50 controls the opening degree of the hollow fiber valve 4513c before the discharge control so as to bring the pressure on the downstream side of the degassing module 451 to atmospheric pressure.SELECTED DRAWING: Figure 3

Description

Technical Field

[0001] The present invention relates to a degassing device, an inkjet recording device, a degassing method, and a program.

Background Art

[0002] Conventionally, an inkjet recording device that ejects ink from nozzles of an inkjet head to form an image on a recording surface of a recording medium is known. In an inkjet recording device, if gas dissolved in the ink remains as bubbles, it may cause problems such as non-ejection of ink from the nozzles. Therefore, there is known a device provided with an external reflux type degassing module on an ink supply path for supplying ink from an ink tank to an inkjet head. In the degassing module, a gas permeable membrane such as a plurality of hollow fiber membranes is housed in a hollow cylindrical body. Since a vacuum pump is connected to at least one end of the gas permeable membrane in the degassing module, the inside of the gas permeable membrane can be decompressed. When the ink comes into contact with the interface of the gas permeable membrane whose inside is decompressed, the dissolved gas in the ink permeates through the gas permeable membrane and is removed (degassed).

[0003] As the degassing module is used, clogging occurs due to ink components (for example, monomers) that have infiltrated into the gas permeable membrane. As a result, the degassing performance of the degassing module deteriorates. Since the degassing module is expensive, it is not cost-effective to replace the degassing module every time the degassing performance deteriorates. Therefore, a configuration is disclosed in which by opening a hollow fiber valve, the ink components infiltrated into the tube of the hollow fiber membrane are discharged (see, for example, Patent Document 1).

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] By the way, when the hollow fiber valve is opened in a vacuum state, the monomer in the monomer trap atomizes due to rapid pressure fluctuations and flows downstream, causing tube blockage. Therefore, if the atmosphere release valve is opened to atmospheric pressure and then the hollow fiber valve is opened and pulled by a vacuum pump, the pressure change becomes gentle and atomization can be prevented. However, there is a concern that the monomer in the hollow fiber membrane may flow backward at the moment the atmosphere release valve is opened, promoting blockage. In addition, there is a concern that the monomer moves to the upper part of the vacuum chamber and blocks the end face, reducing the degassing performance. Patent Document 1 does not describe valve control for achieving the pressure for performing the discharge operation of the ink component. Further, Patent Document 1 does not describe the atomization of the monomer in the monomer trap or the backflow of the monomer in the hollow fiber membrane. Therefore, in the configuration described in Patent Document 1, rapid pressure fluctuations occur due to the opening of the valve. Thus, there is a problem that atomization and backflow of the monomer cannot be prevented, and tube blockage and reduction in degassing performance cannot be suppressed.

[0006] An object of the present invention is to provide a degassing device, an inkjet recording device, a degassing method, and a program that can suppress atomization and backflow of an ink component (monomer) generated from within a degassing module and perform efficient discharge control.

Means for Solving the Problems

[0007] The invention according to claim 1 has been made to achieve the above object, in a degassing device, an external reflux type degassing module having a gas permeable membrane capable of degassing dissolved gas in ink inside; a hollow fiber valve provided on the upstream side of the degassing module; a control unit that performs discharge control for discharging the ink component infiltrated into the gas permeable membrane; and the control unit is characterized in that, before the discharge control, the opening ratio of the hollow fiber valve is controlled to make the pressure on the downstream side of the degassing module atmospheric pressure.

[0008] The invention according to claim 2 is the degassing device according to claim 1, wherein a first detection unit that detects the pressure on the upstream side of the degassing module; a second detection unit that detects the pressure on the downstream side of the degassing module; is provided with the control unit controls the opening ratio of the hollow fiber valve so that the difference between the pressure detected by the first detection unit and the pressure detected by the second detection unit is equal to or less than a predetermined threshold value.

[0009] The invention according to claim 3 is the degassing device according to claim 1, wherein the control unit controls the opening ratio of the hollow fiber valve based on a predetermined opening and closing time.

[0010] The invention according to claim 4 is the degassing device according to claim 1, wherein the control unit controls the opening and closing time of the hollow fiber valve to control the opening ratio.

[0011] The invention according to claim 5 is the degassing device according to claim 1, wherein it is provided with an atmosphere release valve provided on the downstream side of the degassing module, the control unit controls the opening ratios of the hollow fiber valve and the atmosphere release valve before the discharge control to make the pressure on the downstream side of the degassing module equal to the atmospheric pressure.

[0012] The invention according to claim 6 is the degassing device according to claim 5, wherein a first detection unit that detects the pressure on the upstream side of the degassing module; a second detection unit that detects the pressure on the downstream side of the degassing module; is provided with the control unit controls the opening ratios of the hollow fiber valve and the atmosphere release valve so that the difference between the pressure detected by the first detection unit and the pressure detected by the second detection unit is equal to or less than a predetermined threshold value.

[0013] The invention according to claim 7 is the degassing device according to claim 5, wherein the control unit controls the opening ratios of the hollow fiber valve and the atmosphere release valve based on a predetermined opening / closing time.

[0014] The invention according to claim 8 is the degassing device according to claim 5, wherein the control unit controls the opening / closing times of the hollow fiber valve and the atmosphere release valve to control the opening ratio.

[0015] The invention according to claim 9 is the degassing device according to any one of claims 1 to 4, wherein the hollow fiber valve is a needle valve, and the control unit controls the degree of opening of the hollow fiber valve to control the opening ratio.

[0016] The invention according to claim 10 is the degassing device according to any one of claims 5 to 8, wherein the hollow fiber valve and the atmosphere release valve are needle valves, and the control unit controls the degrees of opening of the hollow fiber valve and the atmosphere release valve to control the opening ratio.

[0017] The invention according to claim 11 is in an inkjet recording apparatus, an external reflux type degassing module provided between an ink storage unit for storing ink and an ink ejection head for ejecting ink from a nozzle, and having a gas permeable membrane inside capable of degassing dissolved gas in the ink, a hollow fiber valve provided on the upstream side of the degassing module, a control unit that performs discharge control for discharging ink components infiltrated into the gas permeable membrane, and before the discharge control, the control unit controls the opening ratio of the hollow fiber valve to make the pressure on the downstream side of the degassing module atmospheric pressure.

[0018] The invention according to claim 12 is a degassing method for a degassing device comprising an external reflux type degassing module having a gas permeable membrane capable of degassing dissolved gas in ink therein, and a hollow fiber valve provided upstream of the degassing module, including a control step of performing discharge control for discharging an ink component infiltrated into the gas permeable membrane, wherein the control step is characterized by controlling the opening ratio of the hollow fiber valve to make the pressure on the downstream side of the degassing module equal to atmospheric pressure before the discharge control.

[0019] The invention according to claim 13 is a program for causing a computer of a degassing device including an external reflux type degassing module having a gas permeable membrane capable of degassing dissolved gas in ink therein, and a hollow fiber valve provided upstream of the degassing module, to function as a control unit that performs discharge control for discharging an ink component infiltrated into the gas permeable membrane, wherein the control unit is characterized by controlling the opening ratio of the hollow fiber valve to make the pressure on the downstream side of the degassing module equal to atmospheric pressure before the discharge control.

Advantages of the Invention

[0020] According to the present invention, atomization and backflow of ink components (monomers) generated from within the degassing module can be suppressed, and discharge control can be efficiently performed.

Brief Description of the Drawings

[0021]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Figure 9

Figure 10

Mode for Carrying Out the Invention

[0022] Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

[0023] As shown in FIGS. 1 and 2, the inkjet recording apparatus 1 according to the present embodiment includes a paper feeding unit 10, an image forming unit 20, a paper discharging unit 30, a liquid feeding unit 40, a control unit 50, and a notification unit 60. The liquid feeding unit 40 and the control unit 50 function as the degassing device 100 of the present invention.

[0024] Based on the control of the control unit 50, the inkjet recording apparatus 1 conveys the recording medium P from the paper feeding unit 10 to the image forming unit 20. Then, the control unit 50 forms an image on the recording medium P in the image forming unit 20 with the ink supplied from the liquid feeding unit 40. After image formation, the control unit 50 discharges the recording medium P to the paper discharging unit 30.

[0025] The paper feeding unit 10 stores the recording medium P before image formation. The paper feeding unit 10 conveys the recording medium P to the image forming unit 20 under the control of the control unit 50. The paper feeding unit 10 includes a paper feeding tray 11 and a conveying unit 12.

[0026] The paper feed tray 11 is a plate-shaped member for storing the recording medium P. The paper feed tray 11 is provided so that one or a plurality of recording media P can be placed thereon. The paper feed tray 11 moves up and down according to the amount of the placed recording medium P. The paper feed tray 11 is held at a position where the uppermost recording medium P is conveyed by the conveying unit 12 due to the up and down movement.

[0027] The conveying unit 12 conveys the recording medium P from the paper feed tray 11 to the image forming unit 20. The conveying unit 12 includes a conveying mechanism. The conveying mechanism drives the belt 123 to convey the recording medium P on the belt 123. The belt 123 is annular, and the inside of the ring is supported by a plurality of rollers 121 and 122. The conveying unit 12 includes a supply unit. The supply unit delivers the uppermost recording medium P placed on the paper feed tray 11 onto the belt 123. The conveying unit 12 conveys the recording medium P along the belt 123 by the supply unit.

[0028] The image forming unit 20 records an image on the recording medium P in cooperation with the liquid feeding unit 40 under the control of the control unit 50. The image forming unit 20 includes an image forming drum 21, a delivery unit 22, a paper heating unit 23, a head unit 24, an irradiation unit 25, and a delivery unit 26.

[0029] The image forming drum 21 supports the recording medium P along the cylindrical outer peripheral surface and conveys the recording medium P as it rotates. The conveying surface of the image forming drum 21 faces the paper heating unit 23, the head unit 24, and the irradiation unit 25, and performs image forming processing on the conveyed recording medium P.

[0030] The delivery unit 22 is provided at a position interposed between the conveying unit 12 and the image forming drum 21. The delivery unit 22 includes a claw portion 221 and a delivery drum 222.

[0031] The claw portion 221 is a cylindrical member that supports one end of the recording medium P conveyed by the conveying unit 12. The delivery drum 222 is a member that guides the recording medium P supported by the claw portion 221.

[0032] The delivery unit 22 picks up the recording medium P on the conveyance unit 12 with the claw portion 221 and places it along the outer peripheral surface of the delivery drum 222. By this operation, the delivery unit 22 delivers the recording medium P to the image forming drum 21.

[0033] The paper heating unit 23 includes, for example, a heating wire or the like and generates heat in response to energization. The paper heating unit 23 is controlled by the control unit 50 and generates heat so that the recording medium P passing near it reaches a predetermined temperature. The paper heating unit 23 is provided near the outer peripheral surface of the image forming drum 21 and is located upstream of the head unit 24 in the conveyance direction of the recording medium P.

[0034] A temperature sensor (not shown) is provided near the paper heating unit 23. The control unit 50 detects the temperature near the paper heating unit 23 with the temperature sensor. The control unit 50 controls the heat generation of the paper heating unit 23 based on the detected temperature.

[0035] The head unit 24 forms an image by ejecting ink droplets from nozzles onto the recording medium P. The head unit 24 is provided with those corresponding to each of the colors C (cyan), M (magenta), Y (yellow), and K (black). In FIG. 1, in the conveyance direction of the recording medium P, the head units 24 corresponding to the colors Y, M, C, and K are provided in order from upstream.

[0036] Here, in a plan view, the direction perpendicular to the conveyance direction of the recording medium P is defined as the width direction. The head unit 24 of the present embodiment is provided such that a plurality of them are arranged with a length (width) that covers the entire recording medium P in the width direction. That is, the inkjet recording apparatus 1 is a one-pass type line head type inkjet recording apparatus. The head unit 24 is configured by arranging a plurality of inkjet heads 24a (see FIG. 3). The inkjet head 24a is the ink ejection head of the present invention that ejects ink from nozzles. Note that the number of the head units 24 may be five or more or three or less. Also, a single inkjet head 24a may constitute the head unit 24.

[0037] The ink ejected by the head unit 24 is, for example, ultraviolet curable ink (UV ink). The ultraviolet curable ink is a gel ink that undergoes a phase change between a gel state and a liquid state according to temperature when not irradiated with ultraviolet rays from the irradiation unit 25. The ultraviolet curable ink has a phase change temperature of about 40 to 100 °C, for example, and liquefies uniformly (gelsolates) when heated above the phase change temperature. On the other hand, the ultraviolet curable ink gels at about normal room temperature, that is, about 0 to 30 °C.

[0038] The irradiation unit 25 includes, for example, a fluorescent tube such as a low-pressure mercury lamp. The irradiation unit 25 irradiates energy rays such as ultraviolet rays by the emission of the fluorescent tube. The irradiation unit 25 is provided in the vicinity of the outer peripheral surface of the image forming drum 21. Also, the irradiation unit 25 is provided so as to be located on the downstream side in the conveyance direction of the recording medium P from the head unit 24. The irradiation unit 25 irradiates energy rays onto the recording medium P on which the ink has been ejected. The ink on the recording medium P is cured by the action of the energy rays.

[0039] Note that the fluorescent tube that emits ultraviolet rays is not limited to a low-pressure mercury lamp. The fluorescent tube may be, for example, a mercury lamp having an operating pressure of about several hundred Pa to 1 MPa. Also, the fluorescent tube may be a light source that can be used as a germicidal lamp. The light source that can be used as a germicidal lamp is, for example, a cold cathode tube, an ultraviolet laser light source, a metal halide lamp, a light emitting diode, etc. Among these, it is desirable that the fluorescent tube is a light source that can irradiate ultraviolet rays with higher illuminance and is power saving. The fluorescent tube is, for example, a light emitting diode, etc. Note that the energy rays are not limited to ultraviolet rays, and any energy rays having the property of curing the ink according to the properties of the ink may be used. And the light source is also replaced according to the energy rays.

[0040] In the above, the case where the head unit 24 ejects ultraviolet curable ink has been exemplified, but it is not limited thereto. The ink ejected by the head unit 24 may be aqueous ink or ink having other physical properties.

[0041] The delivery unit 26 includes a conveyance mechanism. The conveyance mechanism drives an annular belt 263 whose inner side is supported by a plurality of rollers 261 and 262 to convey the recording medium P. The delivery unit 26 includes a cylindrical transfer roller 264. The transfer roller 264 transfers the recording medium P from the image forming drum 21 to the conveyance mechanism. The delivery unit 26 conveys the recording medium P delivered onto the belt 263 by the transfer roller 264 and sends it out to the paper discharge unit 30.

[0042] The recording medium P on which an image is formed by the image forming unit 20 is discharged to the paper discharge unit 30. The paper discharge unit 30 includes a plate-shaped paper discharge tray 31 and the like. The recording medium P sent out from the image forming unit 20 by the delivery unit 26 is placed on the paper discharge tray 31. The paper discharge unit 30 stores the recording medium P until the user takes it out.

[0043] Fig. 3 shows a schematic configuration of the liquid supply unit 40. The liquid supply unit 40 includes a plurality of main tanks 41 that store ink of each color. The liquid supply unit 40 supplies the ink of each color in the main tank 41 to each head unit 24. The liquid supply unit 40 enables the ink of each color to be ejected from the nozzles by the control.

[0044] The liquid supply unit 40 includes a main tank 41, a first sub-tank 42, and a second sub-tank 43 which are ink storage parts. Also, the liquid supply unit 40 includes a degassing module 451 that degasses the dissolved gas in the ink before supplying the ink to the head unit 24.

[0045] The main tank 41 is a tank that stores the ink supplied to each part of the liquid supply unit 40. The main tank 41 is, for example, a rigid sealed tank made of metal. The main tank 41 communicates with the first sub-tank 42 via a supply pipe 44. The supply pipe 44 is provided with a supply pump 441 and a supply valve 442.

[0046] The supply pump 441 and the supply valve 442 operate under the control of the control unit 50. When the supply valve 442 is open, the ink in the main tank 41 is supplied to the first sub-tank 42 via the supply pipe 44 by driving the supply pump 441. The main tank 41 is replaceable as a whole. Also, the main tank 41 is detachable from the supply pipe 44 regardless of the driving status of the supply pump 441.

[0047] The first sub-tank 42 is one or a plurality of ink chambers having a smaller volume than the main tank 41. The first sub-tank 42 stores the ink pumped out from the main tank 41 by the supply pump 441. The first sub-tank 42 alleviates the pressure fluctuations due to the pulsation when the supply pump 441 supplies the ink in the main tank 41. The first sub-tank 42 recovers the ink that has not been discharged from the inkjet head 24a from the outlet. The first sub-tank 42 communicates with the second sub-tank 43 via the liquid supply pipe 45. The liquid supply pipe 45 is provided with a degassing module 451, a liquid supply pump 452, a liquid supply valve 453, etc.

[0048] The liquid supply pump 452 sends out the ink flowing out from the ink outlet 4511b (see FIG. 4) of the degassing module 451 to the second sub-tank 43. A check valve (not shown) is provided between the liquid supply pump 452 and the second sub-tank 43 to prevent the backflow of the ink sent to the second sub-tank 43.

[0049] The liquid supply valve 453 is an electromagnetic valve. The liquid supply valve 453 selectively opens and closes the liquid supply pipe 45 under the control of the control unit 50 when the liquid supply pump 452 operates.

[0050] The second sub-tank 43 is a small tank chamber where the ink degassed by the degassing module 451 is temporarily stored. The capacity of the second sub-tank 43 is, for example, approximately the same as that of the first sub-tank 42. The second sub-tank 43 communicates with the inlets of the respective ink jet heads 24a via the supply path 46. The ink in the second sub-tank 43 is supplied to each ink jet head 24a according to the amount of ink ejected from the nozzles. Further, the second sub-tank 43 is provided with back pressure adjusting means (not shown). The back pressure adjusting means prevents the ink from leaking by applying an appropriate negative pressure to the ink jet head 24a.

[0051] Fig. 4 shows the configuration of the degassing module. The degassing module 451 removes the dissolved gas in the flowing-in ink and discharges the degassed ink. The degassing module 451 includes an ink flow-through chamber 4511, a hollow fiber membrane 4512, a first vacuum chamber 4513, and a second vacuum chamber 4514. That is, the degassing module 451 is an external reflux type degassing module having the hollow fiber membrane 4512 inside. The degassing module 451 is provided between the ink storage section (main tank 41, first sub-tank 42) and the ink jet head 24a.

[0052] The ink flow-through chamber 4511 is provided in the central portion inside the casing forming the degassing module 451. The ink flow-through chamber 4511 is provided with an ink inlet 4511a and an ink outlet 4511b. The ink flow-through chamber 4511 receives the inflow of ink from the first sub-tank 42 via the ink inlet 4511a. Further, the ink flow-through chamber 4511 discharges the ink to the second sub-tank 43 via the ink outlet 4511b.

[0053] Note that the ink inlet 4511a is preferably provided on the first end side of the ink flow-through chamber 4511. Further, the ink outlet 4511b is preferably provided on the second end side of the ink flow-through chamber 4511. With such a configuration, the ink is more likely to come into contact with the hollow fiber membrane 4512, so that the degassing efficiency of the degassing module 451 can be improved.

[0054] The hollow fiber membrane 4512 is tubular, and its membrane surface has gas permeability. The hollow fiber membrane 4512 is the gas permeable membrane of the present invention capable of degassing the dissolved gas in the ink, and has a large number of hollow fine fiber structures. A large number of hollow fine fiber structures of the hollow fiber membrane 4512 are bundled and arranged so as to extend in the axial direction of the ink flow chamber 4511.

[0055] In addition, the hollow fiber membrane 4512 is arranged to communicate the first vacuum chamber 4513 and the second vacuum chamber 4514. Therefore, one end of the hollow fiber membrane 4512 is connected to the atmosphere via the hollow fiber valve 4513c. Also, the other end of the hollow fiber membrane 4512 is connected to the vacuum pump 4514e.

[0056] The first vacuum chamber 4513 is provided at the first end of the degassing module 451. The first vacuum chamber 4513 is formed by being partitioned from the ink flow chamber 4511 by a partition wall. The side of the first vacuum chamber 4513 facing the ink flow chamber 4511 is connected to the atmosphere by the first vacuum path 4513a. The first vacuum path 4513a is provided with a first pressure sensor 4513b, a hollow fiber valve 4513c, and the like.

[0057] The first pressure sensor 4513b detects the pressure value in the first vacuum chamber 4513 and transmits the pressure value to the control unit 50. That is, the first pressure sensor 4513b functions as the first detection unit of the present invention that detects the pressure on the upstream side of the degassing module 451. The hollow fiber valve 4513c is a solenoid valve. The hollow fiber valve 4513c is provided on the upstream side of the degassing module 451. The hollow fiber valve 4513c opens the first vacuum path 4513a to the atmosphere according to the control signal of the control unit 50.

[0058] The second vacuum chamber 4514 is provided on the second end side of the degassing module 451. The second vacuum chamber 4514 is formed by being partitioned from the ink circulation chamber 4511 by a partition wall. The second vacuum chamber 4514 communicates with the monomer trap 4514d through a second vacuum path 4514a. In the second vacuum path 4514a, a second pressure sensor 4514b for detecting the pressure value inside thereof, an atmosphere release valve 4514c, and the like are provided.

[0059] The second pressure sensor 4514b detects the pressure in the second vacuum chamber 4514 and transmits the pressure value to the control unit 50. That is, the second pressure sensor 4514b functions as the second detection unit of the present invention for detecting the pressure on the downstream side of the degassing module 451. The control unit 50 controls the drive of the degassing module 451 according to the pressure values acquired from the first pressure sensor 4513b and the second pressure sensor 4514b. The atmosphere release valve 4514c is an electromagnetic valve. The atmosphere release valve 4514c is provided on the downstream side of the degassing module 451. The atmosphere release valve 4514c releases the atmosphere inside the second vacuum path 4514a according to the control signal of the control unit 50.

[0060] The monomer trap 4514d is immersed in the hollow fiber membrane 4512 and stores the monomer (ink component) that has invaded into the second vacuum path 4514a inside. By storing the monomer in the monomer trap 4514d, it is possible to prevent the monomer from reaching the vacuum pump 4514e and causing the vacuum pump 4514e to malfunction.

[0061] The vacuum pump 4514e is a diaphragm pump. Specifically, the vacuum pump 4514e includes a pump chamber having an expandable and contractible diaphragm. The vacuum pump 4514e includes a drive source or the like that operates the diaphragm so that the volume of the pump chamber expands and contracts. The pump chamber includes a suction port having a check valve that allows only the inflow of fluid from the outside. The pump chamber includes a discharge port having a check valve that allows only the discharge of fluid from the inside.

[0062] The vacuum pump 4514e sucks the air in the hollow fiber membrane 4512 under the control of the control unit 50 when the hollow fiber valve 4513c is opened. The inside of the hollow fiber membrane 4512 has the monomer removed and is depressurized by the operation of the vacuum pump 4514e. Therefore, when the ink flowing into the ink circulation chamber 4511 contacts the membrane surface of the hollow fiber membrane 4512, the dissolved gas selectively permeates the membrane surface and is degassed. That is, the dissolved gas (dissolved oxygen) in the ink can be degassed (removed). And the dissolved gas that has passed through the hollow fiber membrane 4512 flows down to the monomer trap 4514d through the second vacuum chamber 4514.

[0063] In the present invention, the external reflux type degassing module 451 configured as described above is adopted. The form of the degassing module 451 is not limited, but for example, it is preferably a sheet in which a plurality of hollow fiber membranes 4512 are knitted together in a braided form. This is because the pores of the hollow fiber membrane 4512 become finer, making it easier for all the ink to pass through the pores of the hollow fiber membrane 4512, thus facilitating an increase in degassing efficiency. Also, with such a configuration, even if the hollow fiber membrane 4512 is flexible, it is easy to obtain a certain level of strength.

[0064] The control unit 50 controls each part constituting the inkjet recording apparatus 1. The control unit 50 is connected to each part constituting the inkjet recording apparatus 1. The control unit 50 includes a CPU 51, a RAM 52, and a ROM 53. The control unit 50 performs discharge control to discharge the ink components infiltrated into the hollow fiber membrane 4512.

[0065] The CPU 51 reads out various programs, data, etc. according to the processing content from a storage device such as the ROM 53 and executes them. Also, the CPU 51 controls the operations of each part of the inkjet recording apparatus 1 according to the executed processing content. The RAM 52 temporarily stores various programs, data, etc. processed by the CPU 51. The ROM 53 stores various programs, data, etc. read out by the CPU 51, etc.

[0066] The notification unit 60 notifies various pieces of information under the control of the control unit 50. The notification unit 60 is, for example, a display unit having a screen, or a communication unit capable of communicating with other devices via a network.

[0067] Next, the control of the inkjet recording apparatus 1 according to this embodiment will be described with reference to the flowchart of Fig. 5. The control of Fig. 5 is a control in which the inkjet recording apparatus 1 performs discharge control after the pressure on the downstream side of the degassing module 451 is set to atmospheric pressure. The control of Fig. 5 is started, for example, when the power of the inkjet recording apparatus 1 is turned on.

[0068] Generally, when the pressure difference between the upstream and downstream of the degassing module 451 becomes large, a large amount of air flows from the upstream to the downstream. This causes the monomers accumulated in the monomer trap to be atomized. Another method for making the pressure downstream of the degassing module 451 atmospheric pressure is to open the atmosphere release valve 4514c. However, there is a concern that the air flowing in from the atmosphere release valve 4514c may cause the monomers in the monomer trap and the monomers accumulated near the outlet of the hollow fiber membrane 4512 to flow back into the hollow fiber membrane 4512. Therefore, before discharge control, the control unit 50 controls the opening rate of the hollow fiber valve 4513c upstream of the degassing module 451 to make the pressure downstream of the degassing module 451 atmospheric pressure. Specifically, the control unit 50 controls the opening rate of the hollow fiber valve 4513c by controlling the opening and closing of the hollow fiber valve 4513c based on the difference (pressure difference) between the upstream pressure and the downstream pressure of the degassing module 451. Specifically, the control unit 50 controls the opening rate by controlling the opening and closing time of the hollow fiber valve 4513c. This makes it possible to suppress sudden pressure fluctuations, thereby preventing atomization of the monomer. Hereinafter, the control for bringing the pressure downstream of the degassing module 451 to atmospheric pressure and the subsequent discharge control will be described with reference to the flowchart of FIG.

[0069] First, the control unit 50 opens (OPEN) the hollow fiber valve 4513c (step S101).

[0070] Next, the control unit 50 acquires the upstream pressure and the downstream pressure, and determines whether the difference (pressure difference) between the upstream pressure and the downstream pressure is equal to or greater than a threshold value D (step S102). The upstream pressure is the pressure on the upstream side (hollow fiber valve 4513c side) of the degassing module 451 measured by the first pressure sensor 4513b. The downstream pressure is the pressure on the downstream side (vacuum pump 4514e side) of the degassing module 451 measured by the second pressure sensor 4514b. The threshold value D is a value that serves as a standard for the pressure difference to the extent that problems caused by sudden pressure fluctuations do not occur. The lower the threshold value D, the more preferable it is, but considering practical time, 40 kPa is preferable. When the control unit 50 determines that it is equal to or greater than the threshold value D (step S102: YES), it proceeds to the next step S103. On the other hand, when the control unit 50 determines that it is less than the threshold value D (step S102: NO), it proceeds to step S106.

[0071] In step S103, the control unit 50 closes (CLOSE) the hollow fiber valve 4513c.

[0072] Next, the control unit 50 acquires the upstream pressure and the downstream pressure, and determines whether the difference (pressure difference) between the upstream pressure and the downstream pressure is equal to or less than the threshold value D (step S104). When the control unit 50 determines that it is equal to or less than the threshold value D (step S104: YES), it proceeds to step S106. On the other hand, when the control unit 50 determines that it is less than the threshold value D (step S104: NO), it proceeds to the next step S105.

[0073] In step S105, the control unit 50 causes the notification unit 60 to notify that there is an error due to clogging of the degassing module. Then, the process ends.

[0074] In step S106, the control unit 50 acquires the downstream pressure, and determines whether the downstream pressure is equal to or greater than a threshold value E. The threshold value E is a value that serves as a standard for atmospheric pressure, and for example, it is -1 kPa. When the control unit 50 determines that it is equal to or greater than the threshold value E (step S106: YES), it proceeds to the next step S107. On the other hand, when the control unit 50 determines that it is less than the threshold value E (step S106: NO), it proceeds to step S101. Then, the processes after step S101 are repeated.

[0075] In step S107, the control unit 50 opens (OPEN) the hollow fiber valve 4513c.

[0076] Next, the control unit 50 drives the vacuum pump 4514e (step S108).

[0077] Next, the control unit 50 determines whether or not a predetermined time has elapsed (step S109). The predetermined time is the driving time of the vacuum pump 4514e, for example, 50 seconds, more preferably 80 seconds. When the control unit 50 determines that the predetermined time has elapsed (step S109: YES), it proceeds to the next step S110. On the other hand, when the control unit 50 determines that the predetermined time has not elapsed (step S109: NO), the process is repeated until the predetermined time elapses.

[0078] Next, the control unit 50 stops the vacuum pump 4514e (step S110).

[0079] Next, the control unit 50 closes (CLOSE) the hollow fiber valve 4513c (step S111).

[0080] As described above, the control unit 50 controls the opening ratio (duty control of the opening and closing time) of the hollow fiber valve 4513c so that the difference between the upstream pressure and the downstream pressure becomes equal to or less than a predetermined threshold value D. Thereby, discharge control can be carried out in a state where rapid pressure fluctuations are suppressed.

[0081] Fig. 6 shows an example of the transition of the pressure difference when the hollow fiber valve 4513c is opened. The horizontal axis represents time, and the vertical axis represents the difference between the upstream pressure and the downstream pressure (pressure difference). In Fig. 6, the symbol L1 represents the pressure difference when the opening ratio control (duty control of the opening and closing time) of the hollow fiber valve 4513c is not performed. The symbol L2 represents the pressure difference when the opening ratio control of the hollow fiber valve 4513c is performed. Note that the example of the symbol L2 shows the case where the control of opening the hollow fiber valve 4513c for 30 msec and closing it for 200 msec is repeated. In the example shown in Fig. 6, it can be seen that the pressure difference L2 when the opening ratio control is performed has less fluctuation than the pressure difference L1 when the opening ratio control is not performed. That is, by performing the opening ratio control, rapid pressure fluctuations can be suppressed.

[0082] Fig. 7 shows an example of the results of evaluating the influence on various problems due to the opening and closing control of each valve. The various problems are "atomization", "clogging backflow", and "lengthening time". Evaluation A indicates that the effect was sufficiently obtained. Evaluation B indicates that the effect was obtained within the allowable range. Evaluation C indicates that the effect was insufficient. When the control of fully opening the hollow fiber valve 4513c is performed, the evaluation of "atomization" is "C". That is, it can be seen that "atomization" could not be suppressed by the control of fully opening the hollow fiber valve 4513c. When the control of fully opening the atmosphere release valve 4514c is performed, the evaluations of "atomization" and "clogging backflow" are "C". That is, it can be seen that neither "atomization" nor "clogging backflow" could be suppressed. When the opening ratio control of the hollow fiber valve 4513c is performed, the evaluation of "atomization" is "B". That is, it can be seen that "atomization" was suppressed within the allowable range. Also, the evaluation of "clogging backflow" is "A". That is, it can be seen that "clogging backflow" was sufficiently suppressed. Also, the evaluation of "lengthening time" is "B". That is, it can be seen that the "lengthening of the control time" was suppressed within the allowable range. Thus, by performing the opening ratio control of the hollow fiber valve 4513c, "atomization" and "clogging backflow" can be suppressed.

[0083] As described above, the degassing device 100 of the inkjet recording apparatus 1 according to the present embodiment includes a degassing module 451, a hollow fiber valve 4513c, and a control unit 50. The degassing module 451 is an external reflux type degassing module having a gas permeable membrane (hollow fiber membrane 4512) capable of degassing dissolved gas in the ink inside. The hollow fiber valve 4513c is provided on the upstream side of the degassing module 451. The control unit 50 performs discharge control for discharging the ink components infiltrated into the gas permeable membrane. Before the discharge control, the control unit 50 controls the opening ratio of the hollow fiber valve 4513c to make the pressure on the downstream side of the degassing module 451 equal to the atmospheric pressure. Therefore, according to the degassing device 100, atomization of the monomer caused by rapid pressure fluctuations and backflow of clogging in the degassing module 451 can be suppressed. As a result, discharge control can be performed efficiently.

[0084] The degassing device 100 also includes a first detection unit (first pressure sensor 4513b) and a second detection unit (second pressure sensor 4514b). The first detection unit detects the pressure on the upstream side of the degassing module 451. The second detection unit detects the pressure on the downstream side of the degassing module 451. The control unit 50 controls the opening ratio of the hollow fiber valve 4513c so that the difference between the pressure detected by the first detection unit and the pressure detected by the second detection unit is equal to or less than a predetermined threshold value. Therefore, according to the degassing device 100, problems caused by rapid pressure fluctuations can be suppressed without adding a new configuration using the existing detection unit. As a result, discharge control can be performed efficiently while suppressing an increase in cost and an increase in the size of the device.

[0085] According to the degassing device 100, the control unit 50 controls the opening and closing time of the hollow fiber valve 4513c to control the opening ratio. Therefore, according to the degassing device 100, by controlling the opening and closing of the hollow fiber valve 4513c in terms of time, the opening ratio can be controlled without performing complex control. As a result, simple and efficient discharge control can be performed.

[0086] As described above, the present invention has been specifically described based on the embodiments. However, the present invention is not limited to the above embodiments and can be modified without departing from the gist thereof.

[0087] (Modification Example 1) For example, in the above embodiment, the opening ratio of the hollow fiber valve 4513c is controlled based on the difference (pressure difference) between the upstream pressure and the downstream pressure. However, the present invention is not limited thereto. For example, the opening ratio of the hollow fiber valve 4513c may be controlled by controlling the opening and closing of the hollow fiber valve 4513c based on a predetermined opening and closing time. Hereinafter, the control of the inkjet recording apparatus 1 according to Modification Example 1 will be described with reference to the flowchart of FIG. 8.

[0088] First, the control unit 50 opens and closes the hollow fiber valve 4513c based on a predetermined opening and closing time (step S201). For example, the control of opening the hollow fiber valve 4513c for 30 msec and closing it for 200 msec is repeated 10 times, and then the control of opening it for 100 msec and closing it for 100 msec is repeated 10 times. Note that the shorter the minimum unit of the switching control of the opening and closing time, the better. However, since there is a limit to the responsiveness of the valve, it is difficult to make the opening and closing time less than 10 msec. Therefore, the minimum unit of the switching control of the opening and closing time is preferably 10 msec or more.

[0089] Next, the control unit 50 acquires the downstream pressure and determines whether the downstream pressure is equal to or higher than a threshold value E (step S202). When the control unit 50 determines that the pressure is equal to or higher than the threshold value E (step S202: YES), it proceeds to the next step S204. On the other hand, when the control unit 50 determines that the pressure is less than the threshold value E (step S202: NO), it proceeds to the next step S203.

[0090] In step S203, the control unit 50 causes the notification unit 60 to notify that there is an error due to clogging of the degassing module. Then, the process ends.

[0091] In step S204, the control unit 50 opens (OPEN) the hollow fiber valve 4513c.

[0092] Hereinafter, since the processes of steps S205 to S208 are the same as the processes of steps S108 to S111 in FIG. 5, the description thereof will be omitted.

[0093] As described above, according to the degassing device 100 according to the first modification, the control unit 50 controls the opening ratio of the hollow fiber valve 4513c based on a predetermined opening / closing time. Therefore, by controlling the opening and closing of the hollow fiber valve 4513c at a predetermined time, the opening ratio can be controlled without performing complicated control. Thereby, simple and efficient discharge control can be performed.

[0094] (Second Modification) In the above embodiment, only the hollow fiber valve 4513c is opened and closed, but the present invention is not limited thereto. For example, in addition to the hollow fiber valve 4513c, the atmosphere release valve 4514c may also be opened and closed. That is, before the discharge control, the control unit 50 may control the opening ratios of the hollow fiber valve 4513c and the atmosphere release valve 4514c so that the pressure on the downstream side of the degassing module 451 becomes atmospheric pressure. Hereinafter, the control of the inkjet recording apparatus 1 according to the second modification will be described with reference to the flowchart of FIG. 9. The control in FIG. 9 controls the opening and closing of the hollow fiber valve 4513c and the atmosphere release valve 4514c based on the difference (pressure difference) between the upstream pressure and the downstream pressure of the degassing module 451, thereby controlling the opening ratios of the hollow fiber valve 4513c and the atmosphere release valve 4514c. Specifically, the control unit 50 controls the opening / closing times of the hollow fiber valve 4513c and the atmosphere release valve 4514c to control the opening ratio.

[0095] First, the control unit 50 opens (OPEN) the hollow fiber valve 4513c (step S301).

[0096] Next, the control unit 50 acquires the upstream pressure and the downstream pressure, and determines whether the difference (pressure difference) between the upstream pressure and the downstream pressure is equal to or greater than a threshold value D (step S302). If the control unit 50 determines that it is equal to or greater than the threshold value D (step S302: YES), it proceeds to the next step S303. On the other hand, if the control unit 50 determines that it is less than the threshold value D (step S302: NO), it proceeds to step S308.

[0097] In step S303, the control unit 50 closes (CLOSE) the hollow fiber valve 4513c.

[0098] Next, the control unit 50 opens (OPEN) the atmosphere release valve 4514c (step S304).

[0099] Next, the control unit 50 acquires the upstream pressure and the downstream pressure, and determines whether the difference (pressure difference) between the upstream pressure and the downstream pressure is equal to or less than a threshold value D (step S305). If the control unit 50 determines that it is equal to or less than the threshold value D (step S305: YES), it proceeds to step S307. On the other hand, if the control unit 50 determines that it is less than the threshold value D (step S305: NO), it proceeds to the next step S306.

[0100] In step S306, the control unit 50 causes the notification unit 60 to notify that there is an error due to clogging of the degassing module. Then, the process ends.

[0101] In step S307, the control unit 50 closes (CLOSE) the atmosphere release valve 4514c.

[0102] Next, the control unit 50 acquires the downstream pressure, and determines whether the downstream pressure is equal to or greater than a threshold value E (step S308). If the control unit 50 determines that it is equal to or greater than the threshold value E (step S308: YES), it proceeds to the next step S309. On the other hand, when the control unit 50 determines that it is less than the threshold value E (step S308: NO), it proceeds to step S301. Thereafter, the processes after step S301 are repeated.

[0103] In step S309, the control unit 50 opens (OPEN) the hollow fiber valve 4513c.

[0104] Hereinafter, since the processes of steps S310 to S313 are the same as the processes of steps S108 to S111 in FIG. 5, the description thereof is omitted.

[0105] As described above, the control unit 50 controls the opening ratios of the hollow fiber valve 4513c and the atmosphere release valve 4514c so that the difference between the upstream pressure and the downstream pressure becomes equal to or less than a predetermined threshold value D. Thereby, discharge control can be carried out while suppressing rapid pressure fluctuations. As shown in FIG. 7, when the opening ratios of the hollow fiber valve 4513c and the atmosphere release valve 4514c are controlled, the evaluation of "atomization" is "B". That is, it can be seen that "atomization" has been suppressed within an allowable range. Also, the evaluation of "clogging backflow" is "B". That is, it can be seen that "clogging backflow" has been suppressed within an allowable range. Further, the evaluation of "lengthening" is "A". That is, it can be seen that the "lengthening" of the control has been sufficiently suppressed.

[0106] As described above, according to the degassing device 100 according to the second modification, before the discharge control, the control unit 50 controls the opening ratios of the hollow fiber valve 4513c and the atmosphere release valve 4514c to make the pressure on the downstream side of the degassing module 451 equal to the atmospheric pressure. Therefore, it is possible to suppress atomization of the monomer due to rapid pressure fluctuations and backflow of clogging in the degassing module 451. Thereby, discharge control can be performed efficiently. Also, according to the degassing device 100 according to the second modification, the control unit 50 controls the opening ratios of the hollow fiber valve 4513c and the atmosphere release valve 4514c so that the difference between the pressure detected by the first detection unit and the pressure detected by the second detection unit becomes equal to or less than a predetermined threshold value. Therefore, it is possible to suppress problems caused by rapid pressure fluctuations without adding a new configuration using the existing detection unit. As a result, it is possible to efficiently perform emission control while suppressing an increase in cost and an increase in the size of the apparatus. Further, by controlling the two valves, the hollow fiber valve 4513c and the atmosphere release valve 4514c, it is possible to shorten the time related to valve control. Further, according to the degassing apparatus 100 according to the second modification, by controlling the opening and closing of each valve by time, it is possible to control the aperture ratio without performing complicated control. As a result, it is possible to simply and efficiently perform emission control.

[0107] (Second Modification) Further, in the above-described second modification, the aperture ratios of the hollow fiber valve 4513c and the atmosphere release valve 4514c are controlled based on the difference (pressure difference) between the upstream pressure and the downstream pressure, but the present invention is not limited thereto. For example, the aperture ratios of the hollow fiber valve 4513c and the atmosphere release valve 4514c may be controlled based on a predetermined opening / closing time. Hereinafter, the control of the inkjet recording apparatus 1 according to the second modification will be described with reference to the flowchart of FIG. 10.

[0108] First, the control unit 50 opens and closes the hollow fiber valve 4513c and the atmosphere release valve 4514c based on a predetermined opening / closing time (step S401). For example, control to open only the hollow fiber valve 4513c for 30 msec and then open only the atmosphere release valve 4514c for 30 msec is repeated 30 times.

[0109] Next, the control unit 50 acquires the downstream pressure and determines whether or not the downstream pressure is equal to or higher than a threshold value E (step S402). When the control unit 50 determines that the pressure is equal to or higher than the threshold value E (step S402: YES), the control unit 50 proceeds to the next step S404. On the other hand, when the control unit 50 determines that the pressure is less than the threshold value E (step S402: NO), the control unit 50 proceeds to the next step S403.

[0110] In step S403, the control unit 50 causes the notification unit 60 to notify that there is an error due to clogging of the degassing module. Then, the process ends.

[0111] In step S404, the control unit 50 opens (OPEN) the hollow fiber valve 4513c.

[0112] Hereinafter, since the processes of steps S405 to S408 are the same as the processes of steps S108 to S111 in FIG. 5, the description thereof is omitted.

[0113] As described above, according to the degassing device 100 according to the third modification, the control unit 50 controls the opening ratios of the hollow fiber valve 4513c and the atmosphere release valve 4514c based on a predetermined opening / closing time. Therefore, by controlling the opening and closing of each valve at a predetermined time, the opening ratio can be controlled without performing complicated control. Thereby, simple and efficient discharge control can be performed.

[0114] (Other modifications) Further, in the above embodiment, the opening ratio of each valve is controlled by controlling the opening / closing time of each valve (hollow fiber valve 4513c and atmosphere release valve 4514c), but the present invention is not limited thereto. For example, each valve may be a needle valve capable of controlling the degree of opening, and the opening ratio of each valve may be controlled by controlling the degree of opening of each valve. As described above, by the control unit 50 controlling the degree of opening of each valve, the opening ratio of each valve can be controlled without performing complicated control. Thereby, simple and efficient discharge control can be performed.

[0115] In addition, regarding the detailed configuration of each device constituting the inkjet recording device and the detailed operation of each device, it can be appropriately changed without departing from the gist of the present invention.

Explanation of reference numerals

[0116] 1 Inkjet recording device 10 Sheet feeding unit 11 Paper feed tray 12 Conveying unit 20 Image forming unit 21 Image forming drum 22 Delivery unit 23 Paper heating unit 24 Head unit 24a Inkjet head (ink ejection head) 25 Irradiation unit 26 Delivery section 30 Paper discharge section 31 Paper discharge tray 40 Liquid supply section 41 Main tank (ink storage section) 42 First sub-tank (ink storage section) 43 Second sub-tank (ink storage section) 451 Degassing module 4511 Ink flow chamber 4512 Hollow fiber membrane (gas permeable membrane) 4513 First vacuum chamber 4513b First pressure sensor (first detection section) 4513c Hollow fiber valve 4514 Second vacuum chamber 4514b Second pressure sensor (second detection section) 4514c Atmosphere release valve 4514d Monomer trap 4514e Vacuum pump 50 Control unit 51 CPU 52 RAM 53 ROM 60 Notification unit 100 Degassing device P Recording medium

Claims

1. An external reflux type degassing module having a gas permeable membrane capable of degassing dissolved gas in ink inside, A hollow fiber valve provided upstream of the degassing module, A control unit that performs discharge control for discharging ink components infiltrated into the gas permeable membrane, Comprising, The control unit controls the opening ratio of the hollow fiber valve to make the pressure on the downstream side of the degassing module equal to atmospheric pressure before the discharge control. The degassing device is characterized by this.

2. A first detection unit that detects the pressure on the upstream side of the degassing module, A second detection unit that detects the pressure on the downstream side of the degassing module, Comprising, The control unit controls the opening ratio of the hollow fiber valve so that the difference between the pressure detected by the first detection unit and the pressure detected by the second detection unit is equal to or less than a predetermined threshold value. The degassing device according to claim 1 is characterized by this.

3. The control unit controls the opening ratio of the hollow fiber valve based on a predetermined opening / closing time. The degassing device according to claim 1 is characterized by this.

4. The control unit controls the opening / closing time of the hollow fiber valve to control the opening ratio. The degassing device according to claim 1 is characterized by this.

5. Comprising an atmosphere release valve provided on the downstream side of the degassing module, The control unit controls the opening ratios of the hollow fiber valve and the atmosphere release valve to make the pressure on the downstream side of the degassing module equal to atmospheric pressure before the discharge control. The degassing device according to claim 1 is characterized by this.

6. A first detection unit that detects the pressure on the upstream side of the degassing module, A second detection unit that detects the pressure on the downstream side of the degassing module, Comprising, The control unit controls the opening ratios of the hollow fiber valve and the atmosphere release valve so that the difference between the pressure detected by the first detection unit and the pressure detected by the second detection unit is equal to or less than a predetermined threshold value. The degassing device according to claim 5 is characterized by this.

7. The control unit controls the opening ratios of the hollow fiber valve and the atmosphere release valve based on a predetermined opening / closing time. The degassing device according to claim 5 is characterized by this.

8. The control unit controls the opening / closing times of the hollow fiber valve and the atmosphere release valve to control the opening ratio. The degassing device according to claim 5 is characterized by this.

9. The hollow fiber valve is a needle valve, The control unit controls the degree of opening of the hollow fiber valve to control the opening ratio. The degassing device according to any one of claims 1 to 4 is characterized by this.

10. The hollow fiber valve and the atmosphere release valve are needle valves, The control unit controls the opening degrees of the hollow fiber valve and the atmosphere release valve to control the aperture ratio, and the degassing device according to any one of claims 5 to 8, characterized in that.

11. An external reflux type degassing module provided between an ink storage unit for storing ink and an ink ejection head for ejecting ink from a nozzle, and having a gas permeable membrane inside capable of degassing dissolved gas in the ink, A hollow fiber valve provided upstream of the degassing module, A control unit that performs discharge control for discharging ink components infiltrated into the gas permeable membrane, Comprising, The control unit controls the aperture ratio of the hollow fiber valve to make the pressure on the downstream side of the degassing module equal to atmospheric pressure before the discharge control, and the inkjet recording apparatus characterized in that.

12. A degassing method for a degassing device comprising an external reflux type degassing module having a gas permeable membrane inside capable of degassing dissolved gas in ink and a hollow fiber valve provided upstream of the degassing module, Including a control step of performing discharge control for discharging ink components infiltrated into the gas permeable membrane, The control step is characterized in that the aperture ratio of the hollow fiber valve is controlled to make the pressure on the downstream side of the degassing module equal to atmospheric pressure before the discharge control.

13. A computer of a degassing device comprising an external reflux type degassing module having a gas permeable membrane inside capable of degassing dissolved gas in ink and a hollow fiber valve provided upstream of the degassing module, Functioning as a control unit that performs discharge control for discharging ink components infiltrated into the gas permeable membrane, The control unit controls the aperture ratio of the hollow fiber valve to make the pressure on the downstream side of the degassing module equal to atmospheric pressure before the discharge control, and the program characterized in that.

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