Degassing module and inkjet recording device

Abstract

To provide a deaeration module which can increase a temperature of an ink more quickly, and to provide an inkjet recording device.SOLUTION: A deaeration module (22) includes: hollow fibers (224) which selectively allow a gas to penetrate therethrough; a supply port (222a) which supplies an ink to a periphery of the hollow fibers (224); an opening (220a) which discharges the ink supplied from the supply port (222a); a housing (220) and a passage pipe (222), a pair of heating parts, which are located at both sides sandwiching a range, in which the hollow fibers (224) are disposed; and a heat conduction member (225) which conducts heat between these heating parts.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present invention relates to a degassing module and an inkjet recording apparatus. [Background technology]

[0002] There is an inkjet recording device that ejects droplets of ink or the like to form an image, a coating, or a structure. In this inkjet recording device, pressure fluctuations are generated in the ink to eject the ink from the nozzles of the inkjet head. If air is contained in the ink, the compression and expansion of the air reduces the pressure fluctuations of the ink, and there is a problem that the desired ink volume and ink ejection speed cannot be obtained. In response to this, there is a conventional inkjet recording device that is equipped with a degassing device that selectively removes air from the ink through a gas-permeable membrane.

[0003] In many cases, the properties of the ink to be ejected, such as its viscosity, depend on temperature. Therefore, a technology is known in which a gas-permeable film is heated to warm the ink and maintain the temperature, thereby improving the degassing ability (Patent Document 1). [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2003-341083 A Summary of the Invention [Problem to be solved by the invention]

[0005] However, the thermal conductivity of gas-permeable resins used in degassing modules is low, making it difficult to heat the entire module quickly and increase its temperature.

[0006] An object of the present invention is to provide a degassing module and an ink jet recording apparatus that can raise the temperature of ink more quickly. [Means for solving the problem]

[0007] In order to achieve the above object, the invention described in claim 1 comprises: A hollow fiber through which gas is selectively permeable; a supply port for supplying ink to the periphery of the hollow fiber; a discharge port for discharging the ink supplied from the supply port; a pair of heating units located on both sides of the area in which the hollow fibers are located; A heat conducting portion that conducts heat between the heating portions; Equipped with 、 The heat conductive portion includes a leaf spring material. The degassing module is characterized by the above.

[0008] The invention described in claim 2 is the degassing module described in claim 1, The heat source is in contact with the heating portion having the larger heat capacity out of the pair of heating portions.

[0009] The invention described in claim 3 is the degassing module described in claim 1 or 2, One of the pair of heating parts is located within a range surrounded by the other of the pair of heating parts. It is characterized by:

[0010] The invention described in claim 4 is the degassing module described in claim 3, The set of heating parts is characterized in that they are respectively positioned on concentric cylinders.

[0011] The invention described in claim 5 is the degassing module described in claim 4, one of the pair of heating units is an ink flow path tube having the supply port, The flow passage pipe is located at the center of the concentric cylinder. It is characterized by:

[0012] The invention described in claim 6 is the degassing module described in claim 4 or 5, The set of heating sections includes a first heating section and a second heating section, The second heating section is located outside the concentric cylinder relative to the first heating section and is in contact with a heat source. It is characterized by:

[0014] Also, claims 7 The invention described is Claim 1~ 6 an ink flow path having the degassing module according to any one of claims 1 to 4; an inkjet head that ejects ink supplied from the ink flow path; A heat source that supplies heat to the heating unit; a suction operation unit that sucks air from within the hollow fibers of the degassing module; The inkjet recording apparatus is characterized by comprising: Effect of the Invention

[0015] According to the present invention, there is an advantage that the temperature of the ink can be increased more quickly in the degassing module. [Brief description of the drawings]

[0016] [Figure 1] FIG. 2 is a diagram illustrating the configuration of ink flow paths in the inkjet recording apparatus of the present embodiment. [Diagram 2] FIG. 2 shows a cross section through the center of the degassing module. [Diagram 3] FIG. 11 is a cross-sectional view showing a degassing module of a first modified example. [Figure 4] FIG. 11 is a cross-sectional view showing a degassing module of a second modified example. [Diagram 5] FIG. 11 is a cross-sectional view showing a degassing module of a third modified example. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0017] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a diagram illustrating the configuration of ink flow paths in an inkjet recording apparatus 1 of this embodiment.

[0018] The inkjet recording apparatus 1 includes an ink supply section 10, an ink flow path section 20 (ink flow path), an inkjet head 30, a suction operation section 40, a heating section 50, and the like.

[0019] The ink supply unit 10 includes an ink tank 11 and a supply pump 12. The supply pump 12 supplies ink from the ink tank 11 to the ink flow path unit 20. The supply pump 12 may be operated intermittently under the control of a control unit (not shown).

[0020] The ink flow path unit 20 supplies the ink supplied from the ink supply unit 10 to the inkjet head 30 at an appropriate temperature. The ink flow path unit 20 has a sub-tank 21, a degassing module 22, a liquid delivery pump 23, and the like between pipes 201. The pipes 201 are not particularly limited, but may have, for example, a hollow circular tube structure.

[0021] The ink flow path section 20 also has a circulation flow path 203 that connects both ends of the degassing module 22, and a circulation pump 25 is included in the middle of this circulation flow path 203 in parallel with the degassing module 22. By having the circulation pump 25 pump the ink, a circulation operation is possible in which the ink flowing out of the degassing module 22 is returned to the upstream side of the degassing module 22, in this case, to the front of the inlet of the degassing module 22.

[0022] The ink flow path section 20 also has a recovery flow path 202 and a valve 26. When the valve 26 is open, the ink stored inside the inkjet head 30 is returned to the subtank 21 via the recovery flow path 202. The valve 26 can be opened, for example, when it is necessary to discharge ink from the inside of the inkjet head 30 for maintenance or the like.

[0023] The heating unit 50 has a heat conductive member 225 (see FIG. 2) that transmits heat from a heat source 60 such as a heater (see FIG. 2), and heats and keeps the ink flow path unit 20 warm so that the ink temperature is kept at an appropriate temperature. The desired ink temperature is determined according to the type of ink, mainly the temperature dependency of the ink viscosity. For example, in the case of ink that changes phase between a sol state and a gel state, it is sufficient to heat and maintain the ink at a temperature that reliably changes the ink to a sol state. The heat source 60 is, for example, an electric heating wire that generates Joule heat when electricity is applied. The heat source 60 is controlled by the control unit to generate heat (such as electricity). Note that the heat source 60 here is not limited to one that directly generates heat, but refers to a member that finally transmits heat generated outside to the heating unit 50 by thermal conduction. For example, a heat conductive plate made of various metals (alloys) is used as the heat conductive member, and is positioned by covering the pipe 201 from the outside or by contacting the side wall of the sub tank 21. The heat conductive member for heating the degassing module 22 will be described later.

[0024] The inkjet head 30 has a plurality of nozzles, a driving element that applies pressure fluctuations to the ink in the nozzles, an inlet pipe 31, and an outlet pipe 32. The inkjet head 30 ejects ink supplied from the ink flow path section 20 via the inlet pipe 31 in response to the operation of the driving element. The inkjet head 30 can eject, via the outlet pipe 32, ink that has been stored in the inkjet head 30 without being ejected from the nozzles. The inkjet head 30 may have a heating section separate from the heating section 50 .

[0025] In addition, the suction operation unit 40 includes a check valve 41, a trap 42, a vacuum pump 43, etc., which are connected in series to the degassing module 22. The vacuum pump 43 is a pump that draws the air area inside the degassing module 22 into a vacuum. The trap 42 stores the ink that flows out from the degassing module 22 and suppresses the ink from flowing into the vacuum pump 43. The check valve 41 prevents ink from flowing back into the degassing module 22 from the trap 42 side.

[0026] Next, the degassing module 22 will be described in detail. FIG. 2 is a cross-sectional view taken through the center of the degassing module 22. As shown in FIG.

[0027] The degassing module 22 of this embodiment is an external perfusion type degassing module having a substantially cylindrical shape using hollow fibers. The degassing module 22 includes a pipe 201a into which ink flows in, an ink chamber 221 for the flowed-in ink, a flow passage pipe 222 (first heating section, one side) located along the central axis of the cylindrical shape (at the center of a concentric cylinder (concentric circle in plan view)), hollow fibers 224 surrounding the flow passage pipe 222 and located on the outside in a range (position range) of a concentric cylinder with the flow passage pipe 222, a housing 220 (second heating section, the other side) covering the outside of the position range of the hollow fibers 224, a pipe 201b connected to the housing 220, and a heat conductive member 225 (heat conductive section).

[0028] The ink flowing into the ink chamber 221 from the pipe 201a flows into the vicinity of one end of the flow passage pipe 222. The flow passage pipe 222 is substantially cylindrical, and has an ink inlet located at one end and a plurality of openings 222a (supply ports) located on the side surface of the cylinder. The ink flowing into the flow passage pipe 222 flows out from the openings 222a and is supplied to the periphery (outer surface side) of the many hollow fibers 224. The many hollow fibers 224 extend substantially parallel to each other in the vertical direction in FIG. 2. After passing through the gaps between the hollow fibers 224, the ink is discharged from the openings 220a (discharge port) to the pipe 201b. Note that the openings 220a are located toward the top of the degassing module 22 in FIG. 2, but are not limited thereto. They may be located near the center, for example.

[0029] The number of hollow fibers 224 is not particularly limited, but it is preferable to have a large number of hollow fibers 224 so that the contact area between the ink and the hollow fiber membrane is large and the amount of ink passing through the position range of the hollow fibers 224 without contacting the hollow fiber membrane is reduced. Each hollow fiber 224 has one end connected to a degassing tube 401 and the other end opposite the end connected to the degassing tube 401 is closed. The inside of the hollow fiber 224 is made into a vacuum state by the operation of a vacuum pump 43 at the end of the degassing tube 401, and the ink on the outside contacts the vacuum surface with the hollow fiber 224 sandwiched between them. The hollow fiber membrane forming the hollow fiber 224 selectively allows the air (gas) in the ink to pass through. The permeated air flows into the degassing tube 401, and the ink is degassed. Note that both ends of the hollow fiber 224 may be opened and vacuum suction is applied from each of the ends.

[0030] The housing 220 and the flow path pipe 222 are made of metal members having high thermal conductivity (usually having a thermal conductivity equal to or higher than that of various SUS (e.g., SUS304)), such as, for example, SUS (stainless steel), aluminum, or copper. The heat source 60 surrounds and contacts the outer periphery of the housing 220, and heat from the heat source 60 is transferred to the housing 220, heating the housing 220. The ink inside the housing 220 is heated inward from the housing 220. The housing 220 and the flow path pipe 222 form a set and are included in the heating unit 50.

[0031] The flow passage tube 222 is separated from the ink chamber 221 by a sealing material such as an O-ring 223. The O-ring 223 may be located, for example, along a groove extending annularly on the surface of the housing 220 facing the flow passage tube 222. This prevents ink from the ink chamber 221 from leaking directly into the housing 220. The O-ring 223 is, for example, a resin member (rubber) or the like, and has an extremely low thermal conductivity compared to conductive metals and the like. Therefore, heat from the housing 220 is not easily transmitted to the flow passage tube 222 via the O-ring 223.

[0032] The housing 220 and the flow path pipe 222 (between the heating parts) are connected by a heat conductive member 225, and heat is conducted. For example, the heat conductive member 225 is annular, and the outer surface is in contact with the housing 220, and the inner surface is in contact with the flow path pipe 222. The heat conductive member 225 may be bonded or welded with an adhesive material having high thermal conductivity. The heat conductive member 225 is not particularly limited, and may be, for example, SUS, aluminum, copper, or the like (usually having a thermal conductivity equal to or higher than various SUS (for example, SUS304)). The heat conductive member 225 may be made of the same material as the housing 220 and the flow path pipe 222. The length (height) of the heat conductive member 225 in the direction along the flow path pipe 222 is not particularly limited, and may be appropriately determined so as to appropriately reduce the amount of delay in the temperature change of the flow path pipe 222 relative to the temperature change of the housing 220.

[0033] A part of the heat of the heated housing 220 is quickly transferred to the flow path pipe 222 via the heat conductive member 225, and the temperature of the flow path pipe 222 becomes close to the temperature of the housing 220. As a result, the ink inside the flow path pipe 222 is heated, and the ink inside the housing 220 is also heated outward from the flow path pipe 222. Note that, in this case, the housing 220 has a much larger volume than the flow path pipe 222, and therefore a larger heat capacity. Therefore, even if a part of the heat flows out from the housing 220 to the flow path pipe 222, the drop in the temperature of the housing 220 is sufficiently small.

[0034] The hollow fiber membrane of the hollow fiber 224 is made of, for example, silicone, and has a very low thermal conductivity compared to SUS. Therefore, it takes time for the inward heat from the housing 220 to reach the flow path tube 222 across the position range of the hollow fiber 224. In contrast, by simultaneously transmitting heat outward from the flow path tube 222 to the position range of the hollow fiber 224 at approximately the same temperature, the ink in the housing 220 can be heated to a stable temperature more quickly and maintained. In particular, in this embodiment, the shortest distance from the heating unit (housing 220 and flow path tube 222) at each position in the position range of the hollow fiber 224 ideally depends only on the distance from the central axis of the concentric cylinder and does not depend on the angle or the position in the direction along the central axis (there may be some exceptions near the end of the position range of the hollow fiber 224), so that the ink is likely to be heated evenly and uniformly.

[0035] A temperature measuring unit 61 is provided inside the housing 220 in the positional range of the hollow fibers 224. The temperature measuring unit 61 is, for example, a thermistor. Data on the temperature measured by the temperature measuring unit 61 may be output to the control unit and used to control the heat generation operation of the heat source 60.

[0036] Fig. 3 is a cross-sectional view showing a degassing module 22a of Modification 1. The cross sections from Fig. 3 onwards are the same as those shown in Fig. 2. The same reference numerals are used to designate the same components as those shown in the above embodiment.

[0037] In the degassing module 22a of this modified example 1, the heat conductive member 225a contacts one end of the flow path tube 222 inside the ink chamber 221, instead of contacting the middle of the flow path tube 222. The heat conductive member 225a is, for example, a leaf spring, and is pressed against one end of the flow path tube 222 to maintain the contact state.

[0038] Such a heat conducting member 225a of the first modified example can be easily obtained since it is only necessary to insert a leaf spring into the ink chamber 221 without modifying the structure of the conventional degassing module 22.

[0039] 4 is a cross-sectional view showing a degassing module 22b of Modification 2. The same components as those shown in the above embodiment are denoted by the same reference numerals.

[0040] The degassing module 22b of the second modification has, in addition to the heat conducting member 225, a heat conducting member 225b that contacts the flow passage pipe 222 at a position different from that of the heat conducting member 225.

[0041] In this way, by transmitting heat from the housing 220 to a plurality of different positions in the flow passage tube 222, it becomes possible to heat the ink inside the housing 220 more quickly and with less unevenness.

[0042] 5 is a cross-sectional view showing a degassing module 22c of Modification 3. The same components as those shown in the above embodiment are denoted by the same reference numerals.

[0043] The degassing module 22c of the third modified example includes not only the flow passage pipe 222 itself but also a heat conductive member 225c around the flow passage pipe 222.

[0044] As described above, the degassing module 22 of this embodiment includes hollow fibers 224, an opening 222a for supplying ink around the hollow fibers 224, an outlet for discharging the ink supplied from the opening 222a, a pair of heating units (the housing 220 and the flow path tube 222) located on either side of the area in which the hollow fibers 224 are located, and a heat conductive member 225 for conducting heat between the heating units (the housing 220 and the flow path tube 222). In this way, by making it possible to heat from both sides of the range in which the hollow fibers 224 are located, it becomes possible to heat the ink around the hollow fibers 224, which have low thermal conductivity, more quickly than ever before. Therefore, in this degassing module 22, the ink can be heated more quickly. In addition, since one set of heating parts is connected by the thermal conductive member 225, there is no need to manage and control the temperature of each heating part separately, and the temperature can be easily controlled by a single control operation. In addition, since there is no need to measure the temperature at multiple points or to provide a driving system for multiple heat sources, the size and manufacturing / operation costs can be reduced. In addition, with ink that gels at room temperature, it is not possible to circulate the ink to hasten the temperature rise until it rises to a temperature at which it becomes a sol, but with this method, the ink inside the degassing module 22 can be heated more quickly than before, and the waiting time at startup, etc. can be shortened.

[0045] Furthermore, the heat source 60 is in contact with the housing 220, which has the larger heat capacity of the pair of heating parts. This makes it possible to suppress a drop in the temperature of the housing 220 even if heat is transferred from the housing 220 to the flow passage tube 222, and makes it possible to heat and increase the temperature of the ink at a more stable temperature.

[0046] Furthermore, the flow path pipe 222 (one of the pair of heating parts) is located within an area surrounded by the housing 220 (the other of the pair of heating parts). Therefore, heat generated from the inner flow path pipe 222 can be efficiently used to heat the ink. In particular, since the entire periphery (here, the area in a plan view) is within the positional range of the hollow fibers 224, it is possible to heat the ink more efficiently than before.

[0047] In addition, each pair of heating units is located on a concentric cylinder. By heating the ink in such a cylindrically symmetrical positional relationship, it is possible to reduce unevenness in the temperature distribution and make the ink temperature more uniform.

[0048] One of the pair of heating parts is an ink flow passage tube 222 having an opening 222a, and the flow passage tube 222 is located at the center of the concentric cylinder. In this way, the ink flows outward from the center, and heat is transferred along the ink flow direction, so that the ink can be heated with less unevenness.

[0049] Moreover, one set of heating parts includes a flow path pipe 222 (first heating part) and a housing 220 (second heating part), and the housing 220 is located outside the flow path pipe 222 of the concentric cylinder and is in contact with the heat source 60. In this way, the structure is easy to simplify because the heat source 60 contacts the outer heating part and the heat is transferred to the inside by the heat conductive member 225. In addition, the outer periphery side usually has a larger area and tends to have a larger heat capacity, so that the heating can be easily controlled.

[0050] Also, like the degassing module 22a of the first modified example, the heat conducting member 225a may include a leaf spring material. With this structure, it is only necessary to insert a leaf spring without modifying the structure of a conventional degassing module, so that it is easy to change the manufacturing method and also easy to suppress increases in cost and labor. Furthermore, since the heat conducting member 225 appropriately contacts the housing 220 and the flow path pipe 222 and conducts heat without being bonded or joined, there is no need to select or use an adhesive member that takes into consideration thermal conductivity, corrosion by ink, and the like.

[0051] Moreover, the inkjet recording device 1 of this embodiment includes an ink flow path section 20 having the above-mentioned degassing modules 22, 22a to 22c, an inkjet head 30 that ejects ink supplied from the ink flow path section 20, a heat source 60 that supplies heat to the housing 220 and the flow path tube 222, which are heating sections, and a suction operation section 40 that sucks in air from within the hollow fibers 224 of the degassing modules 22, 22a to 22c. According to such an inkjet recording apparatus 1, it is possible to quickly heat and increase the temperature of the ink. Therefore, with this inkjet recording apparatus 1, it is possible to degas and eject ink at an appropriate temperature with a shorter waiting time.

[0052] The present invention is not limited to the above-described embodiment, but may be modified in various ways. For example, in the above embodiment, the ink flows from the center to the outside in a concentric cylindrical shape through the gaps in the hollow fibers, but this is not limited to this. The ink may flow in the opposite direction. Alternatively, the ink may be arranged such that the hollow fibers are located between two parallel surfaces, and ink flowing out from one surface flows into the opposite surface. In this case, the heating unit may also be located between the two parallel surfaces, sandwiching the hollow fibers.

[0053] Furthermore, even if the housing 220 is positioned so as to surround the periphery of the flow passage pipe 222, the flow passage pipe 222 does not have to be positioned on a cylinder concentric with the housing 220.

[0054] In the above embodiment, the housing 220 serving as the second heating section is heated by the heat source 60, and the heat is transferred from the housing 220 to the flow path pipe 222 serving as the first heating section by the heat conductive member 225. However, the present invention is not limited to this. The heat conductive member 225 may be heated by the heat source 60, and the heat may be transferred from the heat conductive member 225 to the first heating section (flow path pipe 222) and the second heating section (housing 220).

[0055] In the above embodiment, the heating section on the side heated by the heat source 60 has been described as having a larger heat capacity than the heating section on the side to which heat is transferred by the heat conductive member 225, but this is not limited thereto. The heating section on the side heated by the heat source 60 may have a smaller heat capacity. In this case, the heat conductive member 225 may be positioned so that uneven heating of the heating section on the side to which heat is transferred by the heat conductive member 225 is less likely to occur. In addition, the heat generating operation of the heat source 60 may be controlled so as to appropriately maintain the ratio between the amount of heat transferred by the heat conductive member 225 and the amount of heat supplied by the heat source 60.

[0056] Furthermore, one set of heating parts is not limited to a total of two heating parts, but may be three or more, that is, may have a configuration in which multiple heating parts are located on one of both sides of the positional range of the hollow fibers 224, or may have a configuration in which the above-mentioned positional range is sandwiched from two directions.

[0057] Furthermore, the heat conducting member 225 does not have to be of a single configuration, but may be of a combination of multiple configurations and materials.

[0058] Furthermore, in the above embodiment, the degassing module 22 is located inside the ink flow path section 20 of the inkjet recording apparatus 1, but it may be located outside the inkjet recording apparatus 1 and used. In addition, the specific configurations, structures, operation contents and procedures shown in the above embodiments can be modified as appropriate without departing from the spirit of the present invention. The scope of the present invention includes the scope of the invention described in the claims and its equivalents. [Explanation of symbols]

[0059] 1 Inkjet recording device 10 Ink supply unit 11 Ink tank 12 Supply pump 20 Ink flow path 201, 201a, 201b Piping 202 Recovery channel 203 Circulation Channel 21 Subtank 22, 22a-22c Degassing module 220 Case 220a aperture 221 Ink chamber 222 Flow Pipe 222a aperture 223 O-ring 224 Hollow Fiber 225, 225a-225c Heat conductive materials 23 Liquid delivery pump 25 Circulation Pump 26 Valve 30 Inkjet head 31 Inflow pipe 32 Discharge pipe 40 Suction operation part 401 Degassing tube 41 Check valve 42 Trap 43 Vacuum Pump 50 Heating section 60 Heat source 61 Temperature measurement section

Claims

1. A hollow fiber through which gas is selectively permeable; a supply port for supplying ink to the periphery of the hollow fiber; a discharge port for discharging the ink supplied from the supply port; a pair of heating units located on both sides of the area in which the hollow fibers are located; A heat conducting portion that conducts heat between the heating portions; Equipped with The heat conductive portion includes a leaf spring material. A degassing module comprising:

2. 2. The degassing module according to claim 1, wherein a heat source is in contact with one of said pair of heating parts having a larger heat capacity.

3. One of the heating units in the set is located within a range surrounded by the other heating unit in the set.

3. The degassing module according to claim 1 or 2.

4. 4. The degassing module according to claim 3, wherein said pair of heating sections are respectively positioned on concentric cylinders.

5. one of the pair of heating units is an ink flow path tube having the supply port, The flow passage pipe is located at the center of the concentric cylinder.

5. The degassing module according to claim 4.

6. The set of heating sections includes a first heating section and a second heating section, The second heating section is located outside the concentric cylinder relative to the first heating section and is in contact with a heat source.

6. The degassing module according to claim 4 or 5.

7. An ink flow path having a degassing module according to any one of claims 1 to 6; an inkjet head that ejects ink supplied from the ink flow path; A heat source that supplies heat to the heating unit; a suction operation unit that sucks air from within the hollow fibers of the degassing module; An inkjet recording apparatus comprising:

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