Deaerator, liquid droplet discharge device and deaeration performance reduction determination method and program

Abstract

To provide a deaerator, a liquid droplet discharge device and a deaeration performance reduction determination method and program where the reduction of the deaeration performance of a deaeration module can be determined without lowering productivity.SOLUTION: A deaerator 100 includes an external reflux type deaeration module 451 with a gas permeation membrane 4512 capable of deaerating a dissolved gas in a liquid and a controlling unit 50. The deaeration module 451 includes a first vacuum chamber 4513 communicating with the first end of the gas permeation membrane 4512, a second vacuum chamber 4514 communicating with the second end of the gas permeation membrane 4512 and an atmosphere open valve 4513c opening or closing the inside of the deaeration module 451 to atmosphere. The controlling unit 50 determines the reduction of the deaeration performance of the deaeration module 451 based on pressure difference between the first vacuum chamber 4513 and the second vacuum chamber 4514 at the closing of the atmosphere open valve 4513c.SELECTED DRAWING: Figure 6

Description

[Technical field]

[0001] The present invention relates to a degassing device, a droplet ejection device, and a method and program for determining a decrease in degassing performance. [Background technology]

[0002] Conventionally, a droplet ejection device is known that ejects droplets from a droplet ejection unit onto a recording surface of a recording medium to record an image. In the droplet ejection device, if gas is dissolved in the liquid, this can cause problems. For this reason, the droplet ejection device is provided with a degassing module that degasses the liquid that has passed through a gas-permeable membrane on a liquid supply path to the droplet ejection unit. The degassing module brings the liquid into contact with a gas-permeable membrane that has been depressurized by sucking in the air inside the membrane in an airtight state, thereby allowing the dissolved gas in the liquid to permeate into the gas-permeable membrane.

[0003] However, as the degassing module is used, clogging occurs due to components that have infiltrated into the gas-permeable membrane, causing a decline in the degassing performance. Therefore, for example, Patent Document 1 describes a droplet ejection device that detects the presence or absence of clogging in the gas-permeable membrane based on the air pressure difference between the first and second ends of the gas-permeable membrane, and prompts the replacement of the degassing module if clogging is detected. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2019-130511 A Summary of the Invention [Problem to be solved by the invention]

[0005] However, the invention of Patent Document 1 detects whether or not there is a clog in the gas-permeable membrane when the inside of the gas-permeable membrane is opened to the atmosphere, and therefore has a problem of reducing productivity because the operation of the droplet ejection device must be stopped to detect the clog.

[0006] The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a degassing device, a droplet ejection device, and a method and program for determining a decrease in degassing performance that are capable of determining a decrease in the degassing performance of a degassing module without reducing productivity. [Means for solving the problem]

[0007] In order to solve the above problems, the invention described in claim 1 is a degassing device, an external reflux type degassing module having a gas permeable membrane capable of degassing dissolved gas in a liquid; A control unit, the degassing module includes a first vacuum chamber communicating with a first end of the gas-permeable membrane, a second vacuum chamber communicating with a second end of the gas-permeable membrane, and an atmosphere release valve that opens or closes the inside of the degassing module to the atmosphere; The control unit determines a deterioration in the degassing performance of the degassing module based on a pressure difference between the first vacuum chamber and the second vacuum chamber when the atmosphere release valve is closed.

[0008] The invention described in claim 2 is the degassing device described in claim 1, The control unit determines a deterioration in the degassing performance of the degassing module based on the pressure difference and an influencing factor that affects the pressure difference.

[0009] The invention described in claim 3 is the degassing device described in claim 2, The influencing factors are one or more of the flow rate of the liquid, the degree of use of the degassing device, individual differences between degassing devices, and individual differences between devices incorporating the degassing device.

[0010] The invention described in claim 4 is the degassing device described in claim 3, The control unit obtains the flow rate of the liquid from a liquid flow rate sensor provided in the vicinity of the degassing module.

[0011] The invention described in claim 5 is the degassing device described in claim 3, The control unit obtains a flow rate of the liquid based on a consumption amount of the liquid.

[0012] The invention described in claim 6 is the degassing device described in claim 2, The control unit corrects the pressure difference in accordance with the influencing factor, and determines a deterioration in the degassing performance of the degassing module by comparing the corrected pressure difference with a determination value.

[0013] The invention described in claim 7 is the degassing device described in claim 2, The control unit corrects a determination value in accordance with the influencing factor, and determines a deterioration in the degassing performance of the degassing module by comparing the corrected determination value with the pressure difference.

[0014] The invention described in claim 8 is the degassing device described in claim 6, The determination value is based on the pressure difference in the initial state of the degassing device.

[0015] The invention described in claim 9 is a degassing device according to any one of claims 6 to 8, The control unit has a plurality of levels of the judgment value.

[0016] The invention described in claim 10 is a degassing device according to any one of claims 6 to 8, The control unit performs the correction using a conversion formula created based on the relationship between the flow rate of the liquid and the pressure difference.

[0017] The invention described in claim 11 is the degassing device described in claim 10, The conversion formula is a linear function.

[0018] The invention described in claim 12 is the degassing device described in claim 10, The control unit uses a conversion formula that differs depending on the degree of use of the degassing device.

[0019] The invention described in claim 13 is a degassing device according to any one of claims 1 to 8, The device further includes a notification unit that outputs a message according to the result of the determination by the control unit.

[0020] The invention described in claim 14 is the degassing device described in claim 8, The control unit uses a conversion formula unique to each degassing device.

[0021] The invention described in claim 15 is a degassing device according to any one of claims 1 to 8 and 14, The degassing module degasses the dissolved gas in the UV ink.

[0022] The invention described in claim 16 is a droplet ejection device, A droplet ejection unit that ejects droplets; and a degassing device according to any one of claims 1 to 8 and 14.

[0023] The invention described in claim 17 is as follows: A method for determining a deterioration in degassing performance of a degassing device, comprising: an external reflux type degassing module having a gas permeable membrane capable of degassing dissolved gas in a liquid, the degassing module comprising a first vacuum chamber communicating with a first end of the gas permeable membrane, a second vacuum chamber communicating with a second end of the gas permeable membrane, and an atmosphere release valve opening or closing an interior of the degassing module to the atmosphere, the method comprising: a measuring step of measuring a pressure difference between the first vacuum chamber and the second vacuum chamber when the degassing module is closed to the atmosphere; and a determining step of determining a deterioration in the degassing performance of the degassing module based on the pressure difference.

[0024] The invention described in claim 18 is a method for determining a decrease in degassing performance according to claim 17, The determining step determines a deterioration in the degassing performance of the degassing module based on the pressure difference and an influencing factor that affects the pressure difference.

[0025] The invention described in claim 19 is a program, a computer for a degassing apparatus comprising: an external reflux type degassing module having a gas permeable membrane capable of degassing dissolved gas in a liquid, the degassing module comprising a first vacuum chamber communicating with a first end of the gas permeable membrane, a second vacuum chamber communicating with a second end of the gas permeable membrane, and an atmosphere release valve for opening or closing the inside of the degassing module to the atmosphere; The control unit functions as a control unit that determines a deterioration in the degassing performance of the degassing module based on a pressure difference between the first vacuum chamber and the second vacuum chamber when the atmosphere release valve is closed. Effect of the Invention

[0026] According to the present invention, the deterioration of the degassing performance of the degassing module can be determined without reducing productivity. [Brief description of the drawings]

[0027] [Figure 1] FIG. 2 is a side cross-sectional view of the inkjet recording apparatus. [Diagram 2] FIG. 2 is a schematic diagram of a liquid delivery section. [Diagram 3] FIG. 2 is a side cross-sectional view of the degassing module. [Figure 4] FIG. 1 is a block diagram of an inkjet recording apparatus. [Diagram 5] 4 is a flowchart of a degassing performance degradation determination process according to the first embodiment. [Figure 6] 1 is a graph plotting ink flow rate and pressure difference for each usage frequency of a degasser. [Figure 7] 10 is a flowchart of a degassing performance degradation determination process according to a second embodiment. [Figure 8] 13 is a flowchart of a deaeration performance degradation determination process according to a third embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0028] Hereinafter, a droplet ejection device according to an embodiment of the present invention will be described in detail with reference to the drawings. However, the scope of the invention is not limited to the illustrated examples. In the following description, the same reference numerals are used for components having the same functions and configurations, and the description thereof will be omitted.

[0029] [Overall configuration of inkjet recording device] First, a droplet ejection device equipped with a degassing module will be described with reference to Fig. 1. Fig. 1 is a side cross-sectional view showing the main configuration of an inkjet recording device 1, which is one embodiment of a droplet ejection device equipped with a degassing module 451 (see Fig. 2). The inkjet recording device 1 includes a paper feed section 10, an image forming section 20, a paper discharge section 30, a liquid delivery section 40 (see Fig. 2), a control section 50, and a notification section 60 (all of which are shown in Fig. 4). The liquid delivery section 40 and the control section 50 form a degassing device 100 (see Fig. 4).

[0030] The inkjet recording device 1 conveys the recording medium P from the paper feed unit 10 to the image forming unit 20 under the control of the control unit 50. Then, the control unit 50 forms an image on the recording medium P in the image forming unit 20 using the ink supplied from the liquid delivery unit 40. After the image is formed, the control unit 50 discharges the recording medium P to the paper discharge unit 30.

[0031] (Paper feed section) The paper feed unit 10 stores the recording medium P before an image is formed on it. The paper feed unit 10 conveys the recording medium P to the image forming unit 20 under the control of the control unit 50. The paper feed unit 10 includes a paper feed tray 11, a conveying unit 12, and the like.

[0032] {Paper feed tray} The paper feed tray 11 is a plate-like member that stores recording media P. The paper feed tray 11 is provided so that one or more recording media P can be placed thereon. The paper feed tray 11 moves up and down depending on the amount of recording media P placed thereon. The paper feed tray 11 is held in a position where the top recording medium P is transported by the transport unit 12 depending on the direction of the up and down movement.

[0033] {Transportation section} 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 a belt 123 to convey the recording medium P on the belt 123. The belt 123 is in a ring shape, and the inside of the ring is supported by a plurality of rollers 121 and 122. The conveying unit 12 delivers the top recording medium P placed on the paper feed tray 11 onto the belt 123, and conveys the recording medium P so that it follows the belt 123.

[0034] (Image forming section) The image forming unit 20 cooperates with the liquid sending unit 40 to record an image on the recording medium P 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, a delivery unit 26, and the like.

[0035] {Image forming drum} The image forming drum 21 carries the recording medium P along its cylindrical outer circumferential surface and conveys the recording medium P as it rotates. The conveying surface of the image forming drum 21 faces the paper heating section 23, the head unit 24, and the irradiation section 25, and performs an image forming process on the conveyed recording medium P.

[0036] {Delivery unit} The delivery unit 22 is provided at a position interposed between the transport section 12 and the image forming drum 21. The delivery unit 22 includes a claw portion 221, a delivery drum 222, and the like.

[0037] The claw portion 221 is a cylindrical member that holds one end of the recording medium P transported by the transport unit 12. The delivery drum 222 is a member that guides the recording medium P held by the claw portion 221.

[0038] The delivery unit 22 picks up the recording medium P on the transport section 12 with the claw portion 221 and moves it along the outer circumferential surface of the delivery drum 222. The delivery unit 22 delivers the recording medium P to the image forming drum 21 by this operation.

[0039] {Paper heating section} The paper heating section 23 includes, for example, an electric heating wire, and generates heat in response to the passage of electricity. The paper heating section 23 is controlled by the control section 50, and generates heat so that the recording medium P passing nearby reaches a predetermined temperature. The paper heating section 23 is disposed near the outer circumferential surface of the image forming drum 21, and is located upstream of the head unit 24 in the transport direction of the recording medium P.

[0040] A temperature sensor (not shown) is provided near the paper heating unit 23. The control unit 50 uses the temperature sensor to detect the temperature near the paper heating unit 23. The control unit 50 controls the heat generation of the paper heating unit 23 based on the detected temperature.

[0041] {Head unit} The head unit 24 functions as a droplet ejection unit that ejects ink droplets from nozzles onto the recording medium P to form an image. The head units 24 are provided corresponding to the colors C (cyan), M (magenta), Y (yellow), and K (black). In Fig. 1, the head units 24 corresponding to the colors Y, M, C, and K are provided in this order from upstream in the transport direction of the recording medium P.

[0042] Here, the direction perpendicular to the transport direction of the recording medium P in a plan view is defined as the width direction. In this embodiment, the head units 24 are arranged in a plurality of rows with a length (width) that covers the entire recording medium P in the width direction. In other words, the inkjet recording device 1 is a one-pass type line head inkjet recording device. The head unit 24 is configured by arranging a plurality of inkjet heads 24a (see FIG. 2), which are droplet ejection heads. The number of head units 24 may be five or more or three or less. Also, the head unit 24 may be configured by a single inkjet head 24a.

[0043] The ink ejected by the head unit 24 is, for example, ultraviolet curable ink (UV ink). The ultraviolet curable ink is a gel-like ink that changes phase between a gel state and a liquid (sol) state depending on the temperature when not irradiated with ultraviolet rays from the irradiation unit 25. The ultraviolet curable ink has a phase change temperature of, for example, about 40 to 100°C, and is uniformly liquefied (solized) when heated to or 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.

[0044] {Irradiation unit} 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 emitting light from the fluorescent tube. The irradiation unit 25 is provided near the outer circumferential surface of the image forming drum 21. The irradiation unit 25 is also provided so as to be located downstream of the head unit 24 in the transport direction of the recording medium P. The irradiation unit 25 irradiates the recording medium P onto which the ink has been ejected with energy rays. The ink on the recording medium P is cured by the action of the energy rays.

[0045] The fluorescent tube that emits ultraviolet rays is not limited to a low-pressure mercury lamp. The fluorescent tube may be a mercury lamp with an operating pressure of, for example, several hundred Pa to 1 MPa. The fluorescent tube may be a light source that can be used as a germicidal lamp, for example, a cold cathode fluorescent tube, an ultraviolet laser light source, a metal halide lamp, or a light-emitting diode. Among these, it is preferable that the fluorescent tube is a power-saving light source that can irradiate ultraviolet rays with a higher illuminance. The fluorescent tube is, for example, a light-emitting diode. The energy rays are not limited to ultraviolet rays, and may be energy rays that have the property of curing the ink depending on the properties of the ink. The light source is also replaced depending on the energy rays.

[0046] In the above, the head unit 24 ejects ultraviolet-curable ink, but the present invention is not limited to this. The ink ejected by the head unit 24 may be water-based ink or ink having other physical properties.

[0047] {Delivery Department} The delivery unit 26 includes a transport mechanism. The transport mechanism drives a ring-shaped belt 263, the inside of which is supported by a plurality of rollers 261 and 262, to transport the recording medium P. The delivery unit 26 includes a cylindrical delivery roller 264. The delivery roller 264 delivers the recording medium P from the image forming drum 21 to the transport mechanism. The delivery unit 26 transports the recording medium P delivered onto the belt 263 by the delivery roller 264, and sends it out to the paper discharge unit 30.

[0048] (Paper ejection section) The paper discharge unit 30 discharges the recording medium P on which an image has been formed by the image forming unit 20. 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 removes it.

[0049] (Liquid delivery section) 2 shows a schematic configuration diagram of the liquid sending unit 40. The liquid sending unit 40 includes a plurality of main tanks 41 that store ink of each color. The liquid sending unit 40 supplies the ink of each color in the main tanks 41 to each head unit 24. The liquid sending unit 40 controls the ink of each color to be ejected from the nozzles.

[0050] 2, the liquid sending unit 40 includes a main tank 41, which is a liquid storage unit, a first sub-tank 42, and a second sub-tank 43. The liquid sending unit 40 also includes a degassing module 451 that degasses dissolved gas in the ink before sending the ink to the head unit 24.

[0051] <Main tank> The main tank 41 is a tank that contains ink to be supplied to each part of the liquid delivery unit 40. The main tank 41 is, for example, a rigid sealed tank made of metal. The main tank 41 is in communication with the first sub-tank 42 via a supply pipe 44. A supply pump 441 and a supply valve 442 are provided in the supply pipe 44.

[0052] <Supply pump, supply valve> 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 in its entirety. Moreover, the main tank 41 is detachable from the supply pipe 44 regardless of the driving status of the supply pump 441.

[0053] <First subtank> The first sub-tank 42 is one or more ink chambers having a smaller volume than the main tank 41. The ink pumped out of the main tank 41 by the supply pump 441 is stored in the first sub-tank 42. By providing the first sub-tank 42, pressure fluctuations caused by pulsation when the supply pump 441 supplies ink in the main tank 41 are mitigated. Ink that has not been discharged from the inkjet head 24a is collected in the first sub-tank 42 from an outlet. The first sub-tank 42 is in communication with the second sub-tank 43 via a liquid supply pipe 45. A degassing module 451, a liquid flow rate sensor 452, a liquid supply pump 453, a liquid supply valve 454, etc. are provided in the liquid supply pipe 45. A detailed description of the degassing module 451 will be given later.

[0054] <Liquid flow sensor> The liquid flow sensor 452 is provided near the degassing module 451 on the liquid feed tube 45. The liquid flow sensor 452 detects the flow rate of ink flowing through the liquid feed tube 45 and transmits the detected flow rate to the control unit 50. Note that, although the liquid flow sensor 452 is provided downstream of the degassing module 451 in the example of FIG. 2, the present invention is not limited to this. The liquid flow sensor 452 may be provided upstream of the degassing module 451.

[0055] <Liquid delivery pump> The liquid supply pump 453 supplies the ink flowing out from the ink outlet 4511b (see FIG. 3) of the degassing module 451 to the second sub-tank 43. A check valve (not shown) is provided between the liquid supply pump 453 and the second sub-tank 43 to prevent the ink supplied to the second sub-tank 43 from flowing back.

[0056] <Liquid delivery valve> The liquid sending valve 454 is an electromagnetic valve, and under the control of the control unit 50, selectively opens and closes the liquid sending pipe 45 when the liquid sending pump 453 is in operation.

[0057] <Second subtank> The second sub-tank 43 is a small tank chamber in which the ink degassed in 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 is connected to the inlets of each inkjet head 24a via a supply path 46. The ink in the second sub-tank 43 is supplied to each inkjet head 24a in accordance with the amount of ink ejected from the nozzle. The second sub-tank 43 is also provided with a back pressure adjustment means (not shown) that applies an appropriate negative pressure to the inkjet head 24a to prevent ink from leaking out.

[0058] <Degassing module> 3 shows the degassing module 451. The degassing module 451 removes dissolved gas from the ink that has flowed in, and discharges the degassed ink. The degassing module 451 includes an ink flow chamber 4511, a gas permeable membrane 4512, a first vacuum chamber 4513, and a second vacuum chamber 4514.

[0059] {Ink flow chamber} The ink circulation chamber 4511 is provided in the center of the interior of the casing that forms the degassing module 451. The ink circulation chamber 4511 is provided with an ink inlet 4511a, which receives ink from the first sub-tank 42. The ink circulation chamber 4511 is also provided with an ink outlet 4511b, which allows ink to flow out to the second sub-tank 43.

[0060] As shown in Fig. 3, it is preferable that ink inlet 4511a and ink outlet 4511b are provided at a first end side and a second end side opposite to the first end side of ink flow chamber 4511, respectively. In particular, it is more preferable that ink inlet 4511a and ink outlet 4511b are provided on a substantially diagonal line of ink flow chamber 4511, as shown in Fig. 3. With this configuration, ink can more easily come into contact with gas permeable membrane 4512, and the degassing efficiency of degassing module 451 can be improved.

[0061] {Gas permeable membrane} The gas permeable membrane 4512 is tubular and has a gas permeable membrane surface. The gas permeable membrane 4512 is, for example, a hollow fiber membrane having a structure of many hollow fine fibers, many of which are bundled and arranged to extend in the axial direction of the ink flow chamber 4511.

[0062] 3, the gas-permeable membrane 4512 is disposed so as to communicate with the first vacuum chamber 4513 and the second vacuum chamber 4514. Therefore, a first end of the gas-permeable membrane 4512 is connected to the atmosphere via an atmosphere release valve 4513c described later. A second end of the gas-permeable membrane 4512 is connected to a vacuum pump 4514e described later.

[0063] {First vacuum chamber} The first vacuum chamber 4513 is provided at a first end of the degassing module 451. The first vacuum chamber 4513 is separated 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 a first vacuum path 4513a. As shown in FIG. 2, a first pressure sensor 4513b, an atmosphere release valve 4513c, and the like are provided in the first vacuum path 4513a.

[0064] 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. The atmosphere release valve 4513c is an electromagnetic valve. The atmosphere release valve 4513c opens or closes the inside of the first vacuum path 4513a to the atmosphere in response to a control signal from the control unit 50.

[0065] {Second vacuum chamber} The second vacuum chamber 4514 is provided on a second end side of the degassing module 451, which faces the first vacuum chamber 4513. The second vacuum chamber 4514 is separated from the ink flow chamber 4511 by a partition wall. The second vacuum chamber 4514 communicates with a reduced pressure tank 4514c via a second vacuum path 4514a. As shown in FIG. 2, the second vacuum path 4514a is provided with a second pressure sensor 4514b that detects the pressure value therein.

[0066] The second pressure sensor 4514b detects the pressure in the second vacuum chamber 4514 and transmits the pressure value to the control unit 50. The control unit 50 controls the driving of the degassing module 451 according to the pressure values ​​acquired from, for example, the first pressure sensor 4513b and the second pressure sensor 4514b, as described later. Note that, although FIG. 2 illustrates an example in which the second pressure sensor 4514b is provided in the flow path between the degassing module 451 and the reduced pressure tank 4514c, the present invention is not limited to this. The second pressure sensor 4514b may be provided in the flow path between the reduced pressure tank 4514c and a vacuum pump 4514e, which will be described later.

[0067] The reduced pressure tank 4514c includes an ink discharge valve 4514d and a vacuum pump 4514e. The reduced pressure tank 4514c can store a predetermined volume of gas and can suppress pressure fluctuations in the gas permeable membrane 4512 caused by pulsation of the vacuum pump 4514e. The reduced pressure tank 4514c also stores ink that has infiltrated into the gas permeable membrane 4512 and into the second vacuum path 4514a. The ink stored in the reduced pressure tank 4514c prevents the ink from reaching the vacuum pump 4514e and causing the vacuum pump 4514e to break down. The ink is discharged to the outside by the ink discharge valve 4514d.

[0068] The vacuum pump 4514e is a diaphragm pump. In detail, the vacuum pump 4514e includes a pump chamber with an expandable diaphragm. The vacuum pump 4514e also includes a drive source and the like that operates the diaphragm so that the volume of the pump chamber expands and contracts. The pump chamber includes an intake port with a check valve that allows only the inflow of fluid from the outside. The pump chamber also includes an exhaust port with a check valve that allows only the discharge of fluid from the inside.

[0069] Under the control of the control unit 50, the vacuum pump 4514e sucks the air from inside the gas permeable membrane 4512 when the air release valve 4513c is closed. This operation of the vacuum pump 4514e removes foreign matter from inside the gas permeable membrane 4512 and reduces the pressure. Therefore, when the ink that has flowed into the ink flow chamber 4511 comes into contact with the membrane surface of the gas permeable membrane 4512, the dissolved gas selectively permeates the membrane surface and is degassed. Then, the dissolved gas that has passed through the gas permeable membrane 4512 flows down to the reduced pressure tank 4514c via the second vacuum chamber 4514.

[0070] In the present invention, the external circulation type degassing module 451 configured as described above is adopted. The form of the degassing module 451 is not limited, but it is preferable to use, for example, a sheet in which a plurality of gas-permeable membranes 4512 are woven together in a mesh pattern. With this configuration, the mesh of the gas-permeable membrane 4512 becomes finer, making it easier for all the ink to pass through the mesh of the gas-permeable membrane 4512, and making it easier to increase the degassing efficiency. Furthermore, with this configuration, even a flexible gas-permeable membrane 4512 can easily obtain a certain level of strength.

[0071] (Control unit) Fig. 4 is a block diagram showing the internal configuration of the inkjet recording apparatus 1. A control unit 50 controls each unit constituting the inkjet recording apparatus 1. As shown in Fig. 4, the control unit 50 is connected to each unit constituting the inkjet recording apparatus 1. The control unit 50 includes a CPU (Central Processing Unit) 51, a RAM (Random Access Memory) 52, a ROM (Read Only Memory) 53, etc.

[0072] The CPU 51 reads out various programs, data, etc. corresponding to the processing contents from a storage device such as the ROM 53 and executes them. The CPU 51 also controls the operation of each part of the inkjet recording device 1 according to the processing contents executed. 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.

[0073] (Notification Department) 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.

[0074] [Degassing performance degradation determination process (first embodiment)] The process of determining whether the degassing performance of the degassing module 451 has deteriorated in the inkjet recording apparatus 1 will be described with reference to the flowchart of Fig. 5. In this process, the control unit 50 determines whether the degassing performance of the degassing module 451 has deteriorated. Moreover, the processes of determining whether the degassing performance has deteriorated in the first to third embodiments are all executed with the atmosphere release valve 4513c kept closed.

[0075] First, the control unit 50 acquires the flow rate of ink in the degassing module 451 and the pressure difference between the first pressure sensor 4513b and the second pressure sensor 4514b for a predetermined time (eg, 3 minutes) (step S101).

[0076] The ink flow rate in the degassing module 451 can be obtained based on data measured by, for example, a liquid flow rate sensor 452. However, the liquid flow rate sensor 452 requires space for installation, and must be heat-resistant and ink-resistant. Therefore, the liquid flow rate sensor 452 may not be provided, and the control unit 50 may obtain the ink flow rate in the degassing module 451 from data on the ink consumption. The data on the ink consumption can be calculated, for example, from image data used in image formation.

[0077] After measuring the ink flow rate and pressure difference, the control unit 50 calculates the time average values ​​of the ink flow rate and pressure difference by dividing the measured ink flow rate and pressure difference by the measurement time (step S102).

[0078] The control unit 50 determines a conversion formula between the ink flow rate and the pressure difference (step S103).

[0079] Fig. 6 is a graph plotting the relationship between the ink flow rate and the pressure difference for each frequency of use of the degassing device 100. In Fig. 6, the horizontal axis represents the ink flow rate, and the vertical axis represents the pressure difference. As shown in Fig. 6, the ink flow rate and the pressure difference show a linear relationship that can be expressed as a linear function.

[0080] 6, even when the degassing apparatus 100 is used at the same frequency, the pressure difference increases as the ink flow rate increases. This is because the gas flowing through the gas permeable membrane 4512 is mainly composed of the dissolved gas in the ink taken into the gas permeable membrane 4512 and the gas flowing through the atmosphere release valve 4513c. However, when the ink flow rate increases, the proportion of the dissolved gas in the ink increases and the proportion of the gas flowing through the atmosphere release valve 4513c decreases. Then, even if the vacuum pump 4514e performs a suction operation, the degree of vacuum in the second vacuum chamber 4514 does not increase, and the pressure difference with the first vacuum chamber 4513 increases.

[0081] 6, the degassing device 100 (degassing module 451) deteriorates as it is used, and the pressure difference increases even with the same ink flow rate. Specifically, the more the degassing device 100 deteriorates, the greater the slope and intercept of the line. This is because when clogging occurs in the gas-permeable membrane 4512 and the degassing performance of the degassing module 451 deteriorates, resistance to the air flowing through the gas-permeable membrane 4512 increases, and the pressure difference increases.

[0082] Such influencing factors such as the ink flow rate and the usage of the degassing device 100 have a relatively large effect on the pressure difference when the atmosphere release valve 4513c is closed and the air flow rate is low. Therefore, by correcting the pressure difference to remove the effects of the influencing factors, it becomes possible to accurately determine whether the degassing performance of the degassing module 451 has deteriorated.

[0083] Specifically, first, the control unit 50 selects a provisional conversion formula (the slope of the conversion formula), for example, from formulas (1) to (3), depending on the usage time of the degassing device 100, i.e., the time that the power of the inkjet recording apparatus 1 is turned on.

[0084] (1)y=0.0014x+Y1 (Usage time: 0 hours to 480 hours) (2)y=0.0042x+Y2(Usage time: 480 hours ~ 1920 hours) (3) y = 0.07x + Y3 (usage time: 1920 hours or more) (x: time average value of ink flow rate (ml / min), y: time average value of pressure difference (kpa / min))

[0085] Furthermore, the control unit 50 determines an intercept by substituting the time average values ​​of the ink flow rate and the pressure difference calculated in step S102 into the selected provisional conversion formula, and thereby determines the conversion formula.

[0086] The control unit 50 calculates the pressure difference when the flow rate is zero from the determined conversion formula (step S104).

[0087] Steps S103 and S104 will be described with reference to a specific example. For example, when the usage time of the inkjet recording apparatus 1 is 600 hours, formula (2) is selected as a provisional conversion formula. When the calculated time average value of the ink flow rate is 100 ml / min and the time average value of the pressure difference is 2.5 kPa / min, substituting these values ​​into formula (2) gives Y2=2.08 from 2.5=0.0042×100+Y2, and the conversion formula is y=0.0042x+2.08. Furthermore, when the pressure difference when the ink flow rate is zero is substituted with x=0, it becomes y=2.08 kPa.

[0088] The control unit 50 determines whether the pressure difference calculated in step S104 is equal to or greater than the first determination value (step S105). If it is equal to or greater than the first determination value (step S105; Yes), the control unit 50 causes the notification unit 60 to notify that the degassing module 451 needs to be replaced (step S106).

[0089] If the pressure difference calculated in step S104 is less than the first determination value (step S105; No), the control unit 50 determines whether the calculated pressure difference is equal to or greater than a second determination value that is smaller than the first determination value (step S107). If it is equal to or greater than the second determination value (step S107; Yes), the control unit 50 causes the notification unit 60 to notify that a recovery operation of the degassing module 451 is to be executed (step S108). After the notification by the notification unit 60 of the replacement or recovery of the degassing module 451, the control unit 50 ends the degassing performance degradation determination process.

[0090] If the pressure difference calculated in step S104 is less than the second determination value (step S107; No), the control unit 50 transitions to step S101. That is, the control unit 50 acquires the ink flow rate and the pressure difference again after a predetermined time and continues the degassing performance degradation determination process.

[0091] For example, in the present embodiment, the first determination value is 3.0 kPa and the second determination value is 1.0 kPa. Therefore, since 1.0 kPa < y = 2.08 kPa < 3.0 kPa, the control unit 50 causes the notification unit 60 to notify that a recovery operation of the degassing module 451 is to be executed.

[0092] Examples of the recovery operation of the degassing module 451 include an operation of causing the vacuum pump 4514e to perform a suction operation when the atmosphere release valve 4513c is opened, as described above. Alternatively, an operation of a user connecting a pressurizing source such as a compressor to the first vacuum path 4513a and pressurizing the inside of the gas permeable membrane 4512 can be mentioned. By these operations, foreign matter inside the gas permeable membrane 4512 is removed, and the degassing performance of the degassing module 451 is restored.

[0093] [Effects of the first embodiment] When the atmosphere release valve 4513c is opened to determine the degradation of the degassing performance of the degassing module 451, it is necessary to stop the degassing process of the degassing apparatus 100, and the productivity is reduced by the amount of the determination process. However, as described above, the degassing apparatus 100 according to this embodiment determines the degradation of the degassing performance of the degassing module 451 with the atmosphere release valve 4513c closed. Therefore, it is possible to determine the degradation of the degassing performance of the degassing module 451 without reducing productivity.

[0094] Furthermore, the degassing apparatus 100 according to this embodiment determines a deterioration in the degassing performance of the degassing module 451 based on the pressure difference between the first vacuum chamber 4513 and the second vacuum chamber 4514 and factors that affect the pressure difference, specifically, the ink flow rate and the degree of use of the degassing apparatus 100. Therefore, even when the atmosphere release valve 4513c is closed, it is possible to more accurately determine a deterioration in the degassing performance.

[0095] Moreover, in this embodiment, the liquid degassed by the degassing apparatus 100 is UV ink. Normally, the ink components of UV ink tend to penetrate into the gas permeable membrane 4512, and the degassing performance of the degassing module 451 tends to decrease. However, according to the degassing performance degradation determination process according to this embodiment, it is possible to appropriately and accurately determine the degradation of the degassing performance of the degassing module 451.

[0096] [Degassing performance degradation determination process (second embodiment)] In the above, an example has been given of a configuration in which the ink flow rate and pressure difference in the degassing module 451 are acquired, the ink flow rate is corrected to zero, and whether or not the degassing module 451 is clogged is determined from the pressure difference at that time, but this is not limiting. In the degassing performance degradation determination process according to the second embodiment, a determination value that serves as a criterion for determining whether or not the degassing module 451 is clogged is corrected. Then, by comparing the pressure difference at a predetermined ink flow rate, it is determined whether or not the degassing module 451 is clogged.

[0097] The degassing performance degradation determination process according to the second embodiment will be described with reference to the flowchart of Fig. 7. In the following description, detailed description of contents that are substantially the same as those in the flowchart of Fig. 5 will be omitted.

[0098] Steps S201 to S203 are substantially the same as steps S101 to S103. As described above, the usage time of the inkjet recording apparatus 1 is 600 hours, the time average value of the ink flow rate is 100 ml / min, and the time average value of the pressure difference is 2.5 kPa / min. Therefore, in step S203, the conversion formula is determined to be y=0.0042x+2.08. Also, the first judgment value=3.0, and the second judgment value=1.0.

[0099] The control unit 50 calculates the correction amounts for the first and second judgment values ​​from the conversion formula, and corrects the first and second judgment values ​​(step S204). Specifically, the correction amount is calculated by multiplying the determined slope of the conversion formula by the time average value of the calculated ink flow rate. Then, the calculated correction amount is added to each of the first and second judgment values, thereby correcting the judgment values.

[0100] More specifically, the correction amount in this embodiment is 0.0042×100=0.42. The first determination value is corrected to 3.0+0.42=3.42 (kPa), and the second determination value is corrected to 1.0+0.42=1.42 (kPa).

[0101] The subsequent steps S205 to S208 are substantially similar to steps S105 to S108 in Fig. 5. That is, the control unit 50 compares the time average value of the acquired pressure difference with the corrected determination value, and depending on the result, issues a warning by the notification unit 60, or continues the process of determining whether the degassing performance has deteriorated.

[0102] In this embodiment, since 1.42<2.5<3.42, the control unit 50 causes the notification unit 60 to issue a warning to execute a recovery operation of the degassing module 451.

[0103] [Effects of the second embodiment] The degassing apparatus 100 according to the second embodiment corrects the judgment value in accordance with the influencing factors, and compares the corrected judgment value with the pressure difference to judge the deterioration of the degassing performance of the degassing module 451. With this configuration as well, it is possible to more accurately judge the deterioration of the degassing performance.

[0104] [Degassing performance degradation determination process (third embodiment)] In the first and second embodiments, whether the degassing module 451 is clogged is determined based on whether the pressure difference at a predetermined ink flow rate exceeds the judgment value. However, there are individual differences in the components constituting the degassing device 100 and in the inkjet recording apparatus 1 in which the degassing device 100 is mounted. Therefore, even if the ink flow rate is the same for inkjet recording apparatuses 1 of the same configuration and with the same degree of use, the value of the pressure difference may vary depending on the individual differences. Therefore, even if the pressure difference or the judgment value is corrected, it may not be possible to accurately determine whether the degassing performance of the degassing module 451 has deteriorated.

[0105] Therefore, in the third embodiment, the pressure difference at a predetermined ink flow rate in the initial state of the degassing module 451 is obtained, and a deterioration in the degassing performance of the degassing module 451 is determined by comparing the pressure difference with a determination value based on the pressure difference.

[0106] The degassing performance degradation determination process in this configuration will be described with reference to the flowchart of Fig. 8. In the following description, detailed description of the contents that are substantially the same as those in the flowchart of Fig. 5 will be omitted.

[0107] Steps S301 and S302 are substantially the same as steps S101 and S102. After calculating the time average values ​​of the ink flow rate and pressure difference, the control unit 50 judges whether or not the time average values ​​of the ink flow rate and pressure difference have been acquired a predetermined number of times in the degassing performance degradation judgment process. In this embodiment, it is judged whether or not the time average values ​​of the ink flow rate and pressure difference have been acquired, for example, five or more times (step S303). In detail, in step S304 described later, in order to obtain a conversion formula of the ink flow rate and pressure difference by performing a regression calculation, it is judged whether or not data pairs of the time average values ​​of the ink flow rate and pressure difference at five different levels have been acquired. If the number of times the time average values ​​of the ink flow rate and pressure difference have been acquired is less than five times (step S303; No), the process proceeds to step S301, and the control unit 50 acquires the time average values ​​of the ink flow rate and pressure difference at different levels.

[0108] When the time average values ​​of the ink flow rate and the pressure difference are acquired five or more times (step S303; Yes), the control unit 50 determines a conversion formula for the ink flow rate and the pressure difference by performing a regression calculation on the acquired five data pairs of different levels (step S304).The control unit 50 also calculates the pressure difference when the ink flow rate is zero from the conversion formula (step S305).

[0109] The control unit 50 determines whether or not an initial value, which is the pressure difference when the ink flow rate in the initial state is zero, is stored in the ROM 53 (step S306). If the initial value is not stored (step S306; No), the control unit 50 stores the pressure difference as the initial value (step S307).

[0110] If the initial value has been stored in ROM 53 (step S306; Yes), or steps S308 to S311 after the initial pressure difference has been stored are the same as steps S101 to S104. That is, the ink flow rate and pressure difference are acquired, and a time average value is calculated from the ink flow rate and pressure difference. Then, only the intercept of the conversion formula is updated from the calculated time average value, and the pressure difference when the ink flow rate is zero is calculated from the conversion formula.

[0111] The control unit 50 determines whether the calculated pressure difference is equal to or greater than a first magnification (e.g., 5 times) relative to the initial value (step S312). If the calculated pressure difference is equal to or greater than the first magnification (step S312; Yes), the control unit 50 notifies the notification unit 60 to recommend replacement of the degassing module 451 (step S313).

[0112] If the calculated pressure difference is less than the first magnification (step S312; No), the control unit 50 judges whether the calculated pressure difference is equal to or greater than a second magnification (e.g., twice) that is smaller than the first magnification with respect to the initial value (step S314). If the calculated pressure difference is equal to or greater than the second magnification (step S314; Yes), the control unit 50 causes the notification unit 60 to issue a warning to perform a recovery operation of the degassing module 451 (step S315). After the notification unit 60 issues a warning to replace or perform a recovery operation of the degassing module 451, the control unit 50 ends the degassing performance degradation judgment process.

[0113] If the calculated pressure difference is less than the second magnification (step S314; No), the control unit 50 judges whether or not one day or more has passed since the previous conversion formula was determined (step S316). If one day or more has passed (step S316; Yes), the process proceeds to step S301, where the control unit 50 updates the slope and intercept of the conversion formula. If one day or more has not passed since the previous conversion formula was determined (step S316; No), the process proceeds to step S308, where the control unit 50 updates only the intercept of the conversion formula, and continues the degassing performance degradation judgment process.

[0114] [Effects of the third embodiment] As described above, in this embodiment, the deterioration of the degassing performance of the degassing module 451 is judged by comparing the corrected value of the pressure difference with a judgment value based on the pressure difference acquired in the initial state of the inkjet recording apparatus 1. According to this configuration, the deterioration of the degassing performance of the degassing module 451 is judged based on influencing factors such as individual differences of the degassing system 100 and the inkjet recording apparatus 1. Therefore, the deterioration of the degassing performance can be judged more accurately.

[0115] [Variations] Although the present invention has been specifically described above based on the embodiment, the present invention is not limited to the above embodiment. Of course, the present invention can be modified in various ways within the scope of the invention described in the claims and its equivalents.

[0116] For example, in the above description, when determining a decrease in degassing performance when the atmosphere release valve 4513c is closed, a correction is made according to the influencing factors, but this is not limited to the above. Even when determining a decrease in degassing performance when the atmosphere release valve 4513c is open, that is, when the air flow rate is high and the influence of the influencing factors on the pressure difference is small, a more accurate determination can be made by making a correction according to the influencing factors.

[0117] In the above, the pressure difference or the judgment value is corrected based on the conversion formula, but the present invention is not limited to this. For example, a conversion table may be stored in the ROM 53 in advance, and the pressure difference or the judgment value may be corrected based on the conversion table.

[0118] In the above, the formulas (1) to (3) are given as examples of provisional conversion formulas, but the number of provisional conversion formulas is not limited to three, and may be more or less than three. In addition, the provisional conversion formula is a linear function, but is not limited to this. The provisional conversion formula is not limited to the formulas (1) to (3), and may be determined as appropriate depending on the specifications of the degassing apparatus 100 and the inkjet recording apparatus 1, test results, and the like.

[0119] In addition, in the above, the inkjet recording device 1 that ejects ink has been exemplified as one embodiment of the droplet ejection device, but the present invention is not limited to this. That is, the liquid that is degassed by the degassing device 100 according to the present invention is not limited to ink, and may be, for example, a pretreatment agent, blood, or water. Furthermore, the degassing device 100 is not limited to a configuration provided in a droplet ejection device.

[0120] In the above, examples have been disclosed in which a hard disk or a non-volatile semiconductor memory is used as a computer-readable medium for the program according to the present invention, but the present invention is not limited to these examples. Portable recording media such as CD-ROMs can be used as other computer-readable media. Furthermore, carrier waves can be used as a medium for providing data for the program according to the present invention via a communication line. [Explanation of symbols]

[0121] 1 Inkjet recording device (droplet ejection device) 24a Inkjet head (droplet ejection head) 41 Main tank (liquid storage section) 42 First subtank (liquid storage section) 43 Second subtank (liquid storage section) 451 Degassing Module 4512 Gas permeable membrane 4513 First vacuum chamber 4513c Atmospheric relief valve 4514 Second vacuum chamber 452 Liquid Flow Sensor 50 Control section 60 Notification Department 100 Degassing device

Claims

1. an external reflux type degassing module having a gas permeable membrane capable of degassing dissolved gas in a liquid; A control unit, the degassing module includes a first vacuum chamber communicating with a first end of the gas-permeable membrane, a second vacuum chamber communicating with a second end of the gas-permeable membrane, and an atmosphere release valve that opens or closes the inside of the degassing module to the atmosphere; The control unit determines a deterioration in the degassing performance of the degassing module based on a pressure difference between the first vacuum chamber and the second vacuum chamber when the atmosphere release valve is closed.

2. The degassing apparatus according to claim 1 , wherein the control unit determines a deterioration in the degassing performance of the degassing module based on the pressure difference and an influencing factor that affects the pressure difference.

3. 3. The degassing device according to claim 2, wherein the influencing factors are one or more of a flow rate of the liquid, a usage rate of the degassing device, an individual difference between the degassing devices, and an individual difference between the devices in which the degassing device is installed.

4. The degassing device according to claim 3 , wherein the control unit acquires the flow rate of the liquid from a liquid flow rate sensor provided in the vicinity of the degassing module.

5. The degassing device according to claim 3 , wherein the control unit obtains a flow rate of the liquid based on a consumption amount of the liquid.

6. The degassing device according to claim 2 , wherein the control unit corrects the pressure difference in accordance with the influencing factor, and determines a deterioration in the degassing performance of the degassing module by comparing the corrected pressure difference with a determination value.

7. The degassing device according to claim 2 , wherein the control unit corrects a determination value in accordance with the influencing factor, and determines a deterioration in the degassing performance of the degassing module by comparing the corrected determination value with the pressure difference.

8. The degassing apparatus according to claim 6 , wherein the determination value is based on the pressure difference in an initial state of the degassing apparatus.

9. The degassing apparatus according to claim 6 , wherein the control unit has a plurality of levels of the determination value.

10. The degassing apparatus according to claim 6 , wherein the control unit performs the correction using a conversion formula created based on a relationship between a flow rate of the liquid and the pressure difference.

11. The degassing apparatus according to claim 10 , wherein the conversion formula is a linear function.

12. The degassing device according to claim 10 , wherein the control unit uses the conversion formula that differs depending on the degree of use of the degassing device.

13. The degassing device according to claim 1 , further comprising an alarm unit that outputs a message according to a result of the determination by the control unit.

14. The degassing device according to claim 8 , wherein the control unit uses a conversion formula unique to each degassing device.

15. The degassing device according to claim 1 , wherein the degassing module degasses dissolved gas in UV ink.

16. A droplet ejection unit that ejects droplets; A droplet ejection device comprising: the degassing device according to claim 1 .

17. A method for determining a deterioration in degassing performance of a degassing device, comprising: an external reflux type degassing module having a gas permeable membrane capable of degassing dissolved gas in a liquid, the degassing module comprising a first vacuum chamber communicating with a first end of the gas permeable membrane, a second vacuum chamber communicating with a second end of the gas permeable membrane, and an atmosphere release valve opening or closing an interior of the degassing module to the atmosphere, the method comprising: a measuring step of measuring a pressure difference between the first vacuum chamber and the second vacuum chamber when the degassing module is closed to the atmosphere; and determining whether or not the degassing performance of the degassing module has deteriorated based on the pressure difference.

18. The method for determining a deterioration in degassing performance according to claim 17, wherein the determination step determines the deterioration in the degassing performance of the degassing module based on the pressure difference and an influencing factor that affects the pressure difference.

19. a computer for a degassing apparatus comprising: an external reflux type degassing module having a gas permeable membrane capable of degassing dissolved gas in a liquid, the degassing module comprising a first vacuum chamber communicating with a first end of the gas permeable membrane, a second vacuum chamber communicating with a second end of the gas permeable membrane, and an atmosphere release valve for opening or closing the inside of the degassing module to the atmosphere; a program causing the control unit to function as a control unit that determines a deterioration in the degassing performance of the degassing module based on a pressure difference between the first vacuum chamber and the second vacuum chamber when the atmospheric release valve is closed.

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