Liquid supply system, sub-tank unit, and droplet discharge device

Abstract

To provide a liquid supply system, a sub-tank unit, and a droplet discharge device capable of easily changing a configuration of a liquid tank according to increase / decrease in the number of droplet discharge heads.SOLUTION: In a droplet discharge device 1 that discharges liquid, a liquid supply system 43 which supplies liquid supplied via a first flow path 42 from a main tank 41 to a droplet discharge head 241 includes two or more sub-tank units 432 which heat, maintain heat of, and store the liquid. The first sub-tank unit 432 is connectable to the second sub-tank unit 432.SELECTED DRAWING: Figure 5B

Description

[Technical field]

[0001] The present invention relates to a liquid supply system, a sub-tank unit, and a droplet ejection device. [Background technology]

[0002] 2. Description of the Related Art Conventionally, there is known a droplet ejection device that records an image by ejecting droplets from a droplet ejection head onto a recording surface of a recording medium.

[0003] In a droplet ejection device, a configuration is known in which multiple liquid tanks are provided between a liquid storage unit and a droplet ejection head. For example, Cited Document 1 describes a configuration in which an ink tank is provided between an ink supply unit and an inkjet head, in which a first sub-tank that heats, keeps warm, and stores the ink, and a second sub-tank that applies an appropriate back pressure to the inkjet head are integrally molded. By integrating multiple liquid tanks in this way, the liquid in the liquid tanks can be efficiently heated. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2016-078240 A Summary of the Invention [Problem to be solved by the invention]

[0005] In such a droplet ejection device, it may be necessary to increase or decrease the number of droplet ejection heads, for example, when changing the width of a recording medium. When increasing or decreasing the number of droplet ejection heads, it is also necessary to increase or decrease the number of ink tanks that supply ink to the droplet ejection heads. However, Patent Document 1 does not describe or suggest a configuration for increasing or decreasing the number of ink tanks.

[0006] The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a liquid supply system, a sub-tank unit, and a droplet ejection device that are capable of easily changing the configuration of a liquid tank in accordance with an increase or decrease in the number of droplet ejection heads. [Means for solving the problem]

[0007] In order to solve the above problems, the invention described in claim 1 is: The system is provided with two or more sub-tank units that heat, keep warm and store the liquid supplied from the main tank. A liquid supply system for supplying liquid from the sub-tank unit to a droplet ejection head, The first sub-tank unit and the second sub-tank unit are connectable to each other.

[0008] The invention described in claim 2 is the liquid supply system described in claim 1, the sub-tank unit includes a first sub-tank that heats, keeps warm, and stores liquid, and a second sub-tank that adjusts pressure applied to the liquid and supplies the liquid to the droplet ejection head; The first sub-tank and the second sub-tank are integrally molded.

[0009] The invention according to claim 3 is the liquid supply system according to claim 2, the sub-tank unit includes a liquid supply port through which liquid flows in and a liquid discharge port through which the liquid is discharged; the liquid supply port and the liquid discharge port are disposed at the same positions on opposing side surfaces of the sub-tank unit, When the first sub-tank unit and the second sub-tank unit are connected to each other, the liquid supply port of the first sub-tank unit and the liquid discharge port of the second sub-tank unit communicate with each other.

[0010] The invention according to claim 4 is the liquid supply system according to claim 3, A heat transfer member is provided on a connecting surface between the first sub-tank unit and the second sub-tank unit.

[0011] The invention according to claim 5 is the liquid supply system according to claim 2, a first feed flow path that feeds the liquid discharged from the first sub-tank to the second sub-tank; The liquid ejection head includes a first return flow path that returns the liquid discharged from the first sub-tank to the first sub-tank without passing through the droplet ejection head.

[0012] The invention according to claim 6 is the liquid supply system according to claim 2, a second feed flow path that feeds liquid from the second sub-tank to the droplet ejection head; and a second return flow path that returns the liquid discharged from the second sub-tank to the first sub-tank via the droplet ejection head.

[0013] The invention described in claim 7 is A sub-tank unit that heats, keeps warm, and stores liquid supplied from a main tank of a droplet ejection device and supplies the liquid to a droplet ejection head, It can be connected to other sub-tank units.

[0014] The invention described in claim 8 is a droplet ejection device, A droplet ejection head that ejects liquid; A main tank for storing liquid; and a liquid supply system according to any one of claims 1 to 6. Effect of the Invention

[0015] According to the present invention, it is possible to provide a liquid supply system, a sub-tank unit, and a droplet ejection device that are capable of easily changing the configuration of the liquid tank in response to an increase or decrease in the number of droplet ejection heads. [Brief description of the drawings]

[0016] [Figure 1] FIG. 2 is a side cross-sectional view of the inkjet recording apparatus. [Diagram 2]FIG. 2 is a block diagram showing the functional configuration of inkjet printing. [Diagram 3] FIG. 2 is a schematic diagram of a liquid delivery section. [Figure 4] FIG. 2 is an external view of one subtank unit. [Figure 5A] FIG. 2 is a perspective view of two connected sub-tank units. [Figure 5B] FIG. 2 is a perspective view of two connected sub-tank units. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0017] 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.

[0018] [Overall configuration of inkjet recording device] 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 of the present invention. Fig. 2 is a block diagram showing the functional configuration of the inkjet recording device. 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, and a control section 50.

[0019] (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.

[0020] {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 on it. The paper feed tray 11 moves up and down depending on the amount of recording media P placed on it. By this up and down movement, the paper feed tray 11 is held at a position where the top recording medium P is transported by the transport unit 12.

[0021] {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 inner side of the ring is supported by a plurality of rollers 121 and 122.

[0022] The conveying unit 12 includes a supply unit. The supply unit delivers the top 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.

[0023] (Image forming section) The image forming unit 20 cooperates with the liquid sending unit 40 to perform a recording operation 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.

[0024] {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.

[0025] {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.

[0026] 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.

[0027] 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.

[0028] {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.

[0029] 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.

[0030] {Head unit} The head units 24 form an image by ejecting ink onto the recording medium P. 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 with respect to the transport direction of the recording medium P.

[0031] 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 row 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 241 (see FIG. 3), which are droplet ejection heads.

[0032] The number of head units 24 provided in the image forming section 20 may be three or less, or may be five or more. Also, a configuration in which a single inkjet head 241 constitutes the head unit 24 may be used.

[0033] The ink ejected by the head unit 24 is, for example, ultraviolet curable 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, i.e., about 0 to 30°C.

[0034] {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.

[0035] 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.

[0036] 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.

[0037] {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.

[0038] (Paper ejection section) The recording medium P on which an image has been formed in the image forming section 20 is discharged to the paper discharge section 30. The paper discharge unit 30 includes a plate-shaped paper discharge tray 31. The recording medium P sent 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.

[0039] (Liquid delivery section) 3 is a schematic diagram of the liquid sending unit 40. The liquid sending unit 40 includes a main tank 41, a first flow path 42, and a liquid supply system 43. The liquid sending unit 40 sends ink stored in the main tank 41 to the inkjet head 241 via the first flow path 42 and the liquid supply system 43.

[0040] {Main Tank} The main tank 41 is a tank that contains ink to be supplied to each part of the liquid delivery section 40 except for the main tank 41. The main tank 41 communicates with the liquid supply system 43 via a first flow path 42. The main tank 41 is replaceable in its entirety, and is formed to be detachable from the first flow path 42 regardless of the operating status of the supply pump P1.

[0041] Further, the main tank 41 is provided with an agitation motor 411 and an agitation propeller 412. The agitation motor 411 drives and rotates the agitation propeller 412 under the control of the control unit 50. By this drive, the agitation propeller 412 agitates the ink in the main tank 41 and reduces the viscosity to a predetermined level. This enables the supply pump P1, which will be described later, to deliver the ink.

[0042] <First flow path> The first flow path 42 is a flow path that communicates between the main tank 41 and the liquid supply system 43. The first flow path 42 includes a supply pump P1 and a supply valve 421. The supply pump P1 sends ink in the main tank 41 to the liquid supply system 43 under the control of the control unit 50. The supply valve 421 is an electromagnetic valve, and is opened under the control of the control unit 50 when the supply pump P1 sends liquid.

[0043] {Liquid supply system} The liquid supply system 43 includes, in order from the upstream side in the liquid sending direction, a dissolving flow path 431, at least two sub-tank units 432, a liquid amount detection tank 433, a filter F, a degassing module 434, a liquid sending pump P2, etc. The liquid supply system 43 also includes a second flow path (first sending flow path) 435, a third flow path (first return flow path) 436, a fourth flow path (second sending flow path) 437, and a fifth flow path (second return flow path) 438, etc. The liquid supply system 43 and the inkjet head 241 are mounted on a carriage (not shown) and are movable under the control of the control unit 50.

[0044] <Dissolution flow path> The dissolution flow path 431 heats the ink flowing through the first flow path 42 to a predetermined temperature and reduces the viscosity of the ink under the control of the control unit 50. This action of the dissolution flow path 431 allows the ink to flow through the second flow path 435.

[0045] As will be described later, when additional subtank units 432 are installed, the amount of ink sent from the main tank 41 increases accordingly. Therefore, it is preferable that the dissolution flow path 431 is configured to be increaseable or decreaseable in response to an increase or decrease in the number of subtank units 432, so that the ink can be heated more efficiently. In this embodiment, one dissolution flow path 431 is provided for one subtank unit 432, as shown in FIG.

[0046] {Subtank unit} FIG. 4 is an external view of one subtank unit 432. The subtank unit 432 is made of a metal (such as aluminum) having high thermal conductivity. As shown in FIG. 4, the subtank unit 432 is configured, for example, by integrally molding one first subtank 4321 and one second subtank 4322. The subtank unit 432 is also provided with a heating member 4323. A liquid supply port 4324 and a liquid discharge port 4325 are provided on both side surfaces of the subtank unit 432. An ink flow path that communicates the liquid supply port 4324 and the liquid discharge port 4325 is also provided inside the subtank unit 432.

[0047] [First sub-tank] The first sub-tank 4321 is provided so as to communicate with an ink flow path which communicates the liquid supply port 4324 and the liquid discharge port 4325. The first sub-tank 4321 stores ink supplied from the main tank 41. The first sub-tank 4321 also heats and keeps the stored ink at an appropriate temperature by a heating member 4323.

[0048] 3 and 4, the first sub-tank 4321 is connected to two outlets of the inkjet head 241 through two fifth flow paths 438. With this configuration, ink that is not ejected from the inkjet head 241 is collected in the first sub-tank 4321.

[0049] [Second sub-tank] The second sub-tank 4322 is a small ink chamber that temporarily stores the ink to be sent to the inkjet head 241. The capacity of the second sub-tank 4322 is not particularly limited, but is smaller than or approximately the same as the capacity of the first sub-tank 4321.

[0050] 3, the second sub-tank 4322 communicates with the first sub-tank 4321 via a second flow path 435, and ink in the first sub-tank 4321 flows into the second sub-tank 4322. The second sub-tank 4322 also communicates with an inlet of the inkjet head 241 via a fourth flow path 437, and sends the stored ink to the inkjet head 241.

[0051] 3, in this embodiment, two inkjet heads 241 are configured to communicate with one second sub-tank 4322. Therefore, for example, when adding two inkjet heads 241, one sub-tank unit 432 is added.

[0052] Further, the second sub-tank 4322 is connected to the atmosphere through a back pressure adjustment flow path (not shown). A back pressure adjustment pump is provided in the back pressure adjustment flow path, and under the control of the control unit 50, an appropriate negative pressure is applied to the nozzles of each inkjet head 241 via the second sub-tank 4322 to generate a head meniscus. This control prevents liquid from leaking from the nozzles except during image formation and various maintenance. This control also eliminates the need to place the second sub-tank 4322 below the inkjet head 241 and control the back pressure of the nozzles of the inkjet head 241 based on the head difference. As a result, the second sub-tank 4322 can be placed at any position relative to the inkjet head 241, and the liquid delivery unit 40 and the inkjet recording device 1 can be made smaller in size.

[0053] Further, a liquid level measurement unit 4322a, which is a float sensor, is provided in the second subtank 4322. The liquid level measurement unit 4322a acquires measurement data relating to the liquid level position of the ink in the second subtank 4322 and outputs it to the control unit 50. The control unit 50 calculates the remaining amount of ink in each second subtank 4322 from the measurement data. When the remaining amount of ink in any of the second subtanks 4322 is equal to or less than a predetermined value, the control unit 50 opens an electromagnetic valve 4351 provided in a flow path of the second flow path 435 that communicates with the second subtank 4322. Then, the control unit 50 drives the liquid supply pump P2 to supply liquid to the second subtank 4322. By this control, the amount of ink in each second subtank 4322 is maintained at a predetermined amount.

[0054] The first sub-tank 4321 and the second sub-tank 4322 are connected to the atmosphere through an atmosphere release flow path (not shown). An air pressure pump is provided in the atmosphere release flow path, and pressurizes or depressurizes the first sub-tank 4321 and the second sub-tank 4322 under the control of the control unit 50.

[0055] {Heating element} 4, the heating member 4323 heats the ink in the subtank unit 432, for example, by directly contacting the outer surface of the subtank unit 432. The heating member 4323 is, for example, a rubber heater in which a band-shaped heating element is arranged in a corrugated form on a thin plate-shaped insulating heat-insulating material. When a rubber heater is used as the heating member 4323, the adhesion to the subtank unit 432 is improved.

[0056] {Liquid supply port, liquid discharge port} The liquid supply port 4324 is provided on a first side surface of the subtank unit 432. The liquid supply port 4324 receives ink discharged from a first subtank 4321 or the main tank 41 of another subtank unit 432. The liquid discharge port 4325 is provided on a second side surface facing the first side surface of the subtank unit 432. The liquid discharge port 4325 discharges ink to a first subtank 4321 or the liquid level detection tank 433 of the other subtank unit 432.

[0057] As described above, the liquid supply port 4324 and the liquid discharge port 4325 are provided on opposing surfaces of the subtank unit 432. Moreover, the liquid supply port 4324 and the liquid discharge port 4325 are provided at the same position of the subtank unit 432. Moreover, the liquid discharge port 4325 of the first subtank unit 432 is provided so as to have the same shape as the liquid supply port 4324 of the second subtank unit 432. With this configuration, as shown in Figures 5A and 5B, the ink flow paths can be easily communicated by connecting the subtank units 432 to each other with a connecting member such as a bolt.

[0058] It is preferable to provide an O-ring, which is an elastically deformable circular member, at the communicating portion between the liquid supply port 4324 of the first sub-tank unit 432 and the liquid discharge port 4325 of the second sub-tank unit 432 that are to be connected. By providing an O-ring at the communicating portion between the liquid supply port 4324 and the liquid discharge port 4325, the occurrence of liquid leakage can be prevented.

[0059] 5A, it is preferable to provide a predetermined heat transfer member T on the connecting surface between the first subtank unit 432 and the second subtank unit 432. The heat transfer member T is a member that enhances heat transfer, such as a heat transfer sponge or heat transfer grease. By providing the heat transfer member T, it is possible to reduce temperature unevenness between the multiple subtank units 432. Note that while FIG. 5A illustrates an example of a configuration in which the heat transfer member T is provided on both of the connected subtank units 432, it is sufficient to provide the heat transfer member T on at least one of the subtank units 432.

[0060] Furthermore, the liquid supply port 4324 and the liquid discharge port 4325 may be provided on different faces and / or at different positions. In this case, the two sub-tank units 432 can be connected by communicating the liquid supply port 4324 and the liquid discharge port 4325 with a connecting member having a flexible flow path, such as a tube.

[0061] {Liquid level detection tank} Returning to FIG. 3, the liquid level detection tank 433 is connected to the liquid outlet 4325 of the subtank unit 432. In this embodiment, the liquid level detection tank 433 is connected to all of the first subtanks 4321 of the subtank units 432 so as to be at the same height. The liquid level detection tank 433 is provided so that its upper portion communicates with the upper portions of all of the first subtanks 4321. The liquid level detection tank 433 is provided so as to communicate with the atmosphere via the above-mentioned atmosphere release flow path. The liquid level detection tank 433 is provided with a liquid level measurement unit 4331 which is a float sensor.

[0062] With this configuration, the liquid level of the liquid level detection tank 433 becomes equal to that of all of the first sub-tanks 4321. Therefore, the liquid level measurement unit 4331 can acquire the liquid level of all of the first sub-tanks 4321.

[0063] It is also possible to provide a liquid level measuring unit in each of the first sub-tanks 4321 to acquire the liquid level of each of the first sub-tanks 4321 without providing the liquid level detection tank 433. However, in the case of a configuration in which the liquid level detection tank 433 is provided, it is necessary to provide only one liquid level measuring unit 4331 in the liquid level detection tank 433, which is preferable from the viewpoint of cost.

[0064] {Filter} The filter F removes foreign matter from the ink by filtering the ink passing through it. The filter F is formed of, for example, a mesh-like porous metal or resin body, and has meshes of a predetermined size.

[0065] <Degassing module> The degassing module 434 is, for example, an external reflux type hollow fiber membrane degassing module in which the inside of a plurality of hollow fiber membranes is degassed and ink flows outside the hollow fiber membranes. The degassing module 434 removes air bubbles dissolved in or contained in the ink.

[0066] If air is mixed in the ink, the liquid feed pump P2 described below may be unable to feed the ink due to so-called "air entrapment." Therefore, the degassing module 434 is provided upstream of the liquid feed pump P2 in the liquid feed direction. The degassing module 434 may be an internal return type that returns the ink to the hollow portion inside the hollow fiber.

[0067] {Second flow path} The second flow path 435 is a feed flow path that connects the various components of the liquid supply system 43 and feeds the liquid in the first sub-tank 4321 to the second sub-tank 4322.

[0068] {Liquid delivery pump} The liquid sending pump P2 is provided in the second flow path 435, and sends the ink that has passed through the degassing module 434. The liquid sending pump P2 is, for example, a known diaphragm pump, and sends the ink in the second flow path 435 by driving a diaphragm under the control of the control unit 50.

[0069] {Third Stream} The third flow path 436 is provided so as to connect the end and start of the second flow path 435. The third flow path 436 allows the ink sent from the first sub-tank 4321 to be returned to the first sub-tank 4321 without passing through the inkjet head 241. By providing the liquid supply system 43 with such a circulation structure, it is possible to eliminate temperature unevenness that occurs when the ink supply is stopped. Furthermore, by providing the liquid supply system 43 with such a circulation structure, the circulated ink can be filtered again by the filter F. Furthermore, the circulated ink can be degassed again by the degassing module 434.

[0070] Further, a check valve 4361 that allows ink to flow only from the downstream side in the liquid sending direction to the upstream side in the liquid sending direction is provided in the third flow path 436. The check valve 4361 is opened, for example, when none of the solenoid valves provided in the second flow path 435 is opened and the internal pressure rises to a predetermined value.

[0071] (4th flow path, 5th flow path) The fourth flow path 437 is a flow path that connects the second sub-tank 4322 and the inlet of the inkjet head 241 to send the ink in the second sub-tank 4322 to the inkjet head 241. The fifth flow path 438 is a flow path that connects the outlet of the inkjet head 241 and the first sub-tank 4321 to return the ink in the inkjet head 241 to the first sub-tank 4321. The fourth flow path 437 and the fifth flow path 438 can be heated by a heating means (not shown). The fourth flow path 437 and the fifth flow path 438 are made of, for example, a resin or a material with good heat conductivity. The fourth flow path 437 may be provided with the filter F as described above. The fifth flow path 438 is provided with an electromagnetic valve 4381.

[0072] (Control unit) Returning to Fig. 2, the control unit 50 controls each unit constituting the inkjet recording apparatus 1. As shown in Fig. 2, 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, and a ROM (Read Only Memory) 53.

[0073] 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 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.

[0074] [Effects of the embodiment] As described above, the liquid supply system 43 according to this embodiment includes two or more sub-tank units 432 that heat, keep warm, and store ink supplied from the main tank 41. The liquid supply system 43 also supplies ink from the sub-tank units 432 to the inkjet heads 241. The first sub-tank unit 432 and the second sub-tank unit 432 are connectable. With this configuration, the number of sub-tank units 432 can be increased or decreased in accordance with an increase or decrease in the number of inkjet heads 241, making it possible to easily change the configuration of the ink tanks.

[0075] The subtank unit 432 also includes a first subtank 4321 that heats, keeps warm, and stores ink. The subtank unit 432 also includes a second subtank 4322 that adjusts the pressure applied to the ink and supplies the ink to the inkjet head 241. In the subtank unit 432, the first subtank 4321 and the second subtank 4322 are integrally molded. With this configuration, heat applied to the first subtank 4321 is transferred to the second subtank 4322, heating the ink therein. As a result, it is possible to suppress the occurrence of ejection defects caused by low-temperature ink being supplied to the inkjet head 241.

[0076] Furthermore, the liquid supply port 4324 and the liquid discharge port 4325 of the subtank unit 432 are disposed at the same positions on opposing side surfaces of the subtank unit 432. Furthermore, when the subtank units 432 are connected to each other, the liquid supply port 4324 and the liquid discharge port 4325 communicate with each other. With this configuration, there is no need to provide a separate member that communicates the liquid supply port 4324 and the liquid discharge port 4325, and the subtank units 432 can be more easily connected to each other.

[0077] In addition, a heat transfer member T is provided on the connection surface of the sub-tank units 432. With this configuration, the air layer that is generated when the sub-tank units 432 are connected is blocked, improving the heat transfer efficiency. As a result, the heat distribution of the multiple sub-tank units 432 becomes uniform.

[0078] The liquid supply system 43 also includes a second flow path 435 that sends the ink discharged from the first subtank 4321 to the second subtank 4322. The liquid supply system 43 also includes a third flow path 436 that returns the ink discharged from the first subtank 4321 to the first subtank 4321 without passing through the inkjet head 241. With this configuration, the ink is circulated to eliminate temperature unevenness that occurs when the liquid supply is stopped. Furthermore, in addition to this configuration, foreign matter and air can be removed by providing a filter F and a degassing module 434 in the second flow path 435.

[0079] The liquid supply system 43 also includes a fourth flow path 437 that sends liquid from the second sub-tank 4322 to the droplet ejection head 241. The liquid supply system 43 also includes a fifth flow path 438 that returns ink discharged from the second sub-tank 4322 to the first sub-tank 4321 via the droplet ejection head 241. With this configuration, the ink circulation can eliminate temperature unevenness that occurs when the liquid supply is stopped. Also, air bubbles in the droplet ejection head 241 can be returned to the first sub-tank 4321.

[0080] [Other configurations] 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, various modifications are possible within the scope of the invention described in the claims and its equivalents.

[0081] For example, in the above description, the subtank unit 432 includes one first subtank 4321 and one second subtank 4322. However, the present invention is not limited to this. That is, the subtank unit 432 may include, for example, one first subtank 4321 and multiple second subtanks 4322.

[0082] In addition, in the subtank unit 432, the first subtank 4321 and the second subtank 4322 are integrally molded, but this is not limited to the above. That is, the first subtank 4321 and the second subtank 4322 of the subtank unit 432 may be separable.

[0083] In addition, in the above, the inkjet recording apparatus 1 including a plurality of connected sub-tank units 432 has been exemplified, but the present invention is not limited to this. That is, the inkjet recording apparatus 1 may include a single sub-tank unit 432.

[0084] In addition, in the above, the liquid droplet ejection device is the inkjet recording device 1, but the present invention is not limited to this. That is, the present invention may be applied to various liquid droplet ejection devices that eject droplets of liquid other than ink from nozzles. [Explanation of symbols]

[0085] 1 Inkjet recording device (droplet ejection device) 241 Inkjet head (droplet ejection head) 41 Main Tank 43 Liquid Supply System 432 Subtank Unit 4321 1st Subtank 4322 Second subtank 4324 Liquid supply port 4325 Liquid outlet 435 Second flow path (first feed flow path) 436 3rd flow path (1st return flow path) 437 4th flow path (2nd feed flow path) 438 5th flow path (2nd return flow path) T Heat transfer material

Claims

1. The liquid supply system includes two or more sub-tank units that heat, keep warm, and store the liquid supplied from the main tank. A liquid supply system for supplying liquid from the sub-tank unit to a droplet ejection head, A liquid supply system in which a first sub-tank unit and a second sub-tank unit are connectable.

2. the sub-tank unit includes a first sub-tank that heats, keeps warm, and stores liquid, and a second sub-tank that adjusts pressure applied to the liquid and supplies the liquid to the droplet ejection head; The liquid supply system according to claim 1 , wherein the first sub-tank and the second sub-tank are integrally formed.

3. the sub-tank unit includes a liquid supply port through which liquid flows in and a liquid discharge port through which the liquid is discharged; the liquid supply port and the liquid discharge port are disposed at the same positions on opposing side surfaces of the sub-tank unit, 3. A liquid supply system according to claim 2, wherein when the first sub-tank unit and the second sub-tank unit are connected, the liquid supply port of the first sub-tank unit and the liquid discharge port of the second sub-tank unit are connected to each other.

4. 4. The liquid supply system according to claim 3, further comprising a heat transfer member provided on a connecting surface between the first sub-tank unit and the second sub-tank unit.

5. a first feed flow path that feeds the liquid discharged from the first sub-tank to the second sub-tank; The liquid supply system according to claim 2 , further comprising: a first return flow path that returns the liquid discharged from the first sub-tank to the first sub-tank without passing through the droplet ejection head.

6. a second feed flow path that feeds liquid from the second sub-tank to the droplet ejection head; The liquid supply system according to claim 2 , further comprising: a second return flow path that returns the liquid discharged from the second sub-tank to the first sub-tank via the droplet ejection head.

7. A sub-tank unit that heats, keeps warm, and stores liquid supplied from a main tank of a droplet ejection device and supplies the liquid to a droplet ejection head, A subtank unit that can be connected to other subtank units.

8. A droplet ejection head that ejects liquid; A main tank for storing liquid; A droplet ejection device comprising: the liquid supply system according to claim 1 .

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