Inkjet recording apparatus

Abstract

An inkjet recording apparatus (1) includes a degasser (30) for degassing ink (I) flowing in a second flow path (92), and a circulation pump (62) for applying pressure to a circulation path of the ink (I) including a sub-tank (52), the second flow path (92), the degasser (30), a third flow path (93), a print head (11), and a fourth flow path (94) to generate a flow of the ink (I) in the circulation path. The degasser (30) has an ink inlet (12A) and an ink outlet (12B), and the ink inlet (12A) is arranged closer to the print head (11) than the ink outlet (12B) in a direction in which ink (I) is ejected from a nozzle row (16).

Description

Technical Field

[0001] This application relates to an inkjet recording apparatus configured to record (print) by ejecting ink from a printhead onto a recording medium. Background Technology

[0002] Patent Document 1 describes an ink supply device comprising: a main tank storing ink; a first flow path through which ink flows from the main tank; a sub-tank temporarily storing ink from the first flow path and regulating the pressure of the ink; a second flow path through which ink flows from the sub-tank; a printhead portion ejecting ink supplied from the second flow path; a degassing device installed in a portion of the path from the main tank to the printhead portion; and a return flow path for returning ink downstream of the sub-tank to the sub-tank.

[0003] List of patent documents

[0004] Patent documents

[0005] Patent Document 1: Japanese Patent Application Publication No. 2005-59476

[0006] The technical problem to be solved by the present invention

[0007] However, in the ink supply device described in Patent Document 1, the positional relationship between the printhead section and the degasser is not clearly defined, and depending on the environment in which the device is used, the ink path may be split inside the degasser during ink filling, causing ink supply problems. Furthermore, since the sub-canister is located downstream of the degasser in the path to the printhead unit, it takes time for the degassed ink to reach the printhead unit, and the initial printing from the non-printing state to the printing state may also take time. Summary of the Invention

[0008] One objective of this application is to provide a technique that can further reduce initial printing time.

[0009] Technical means to solve technical problems

[0010] To achieve the above objectives, the inkjet recording apparatus of this application includes: a printhead having a nozzle array configured to eject ink; a main tank configured to store the ink; a first flow path through which the ink flows from the main tank; a sub-tank connected to the first flow path and configured to temporarily store the ink flowing into the first flow path; a second flow path through which the ink flows from the sub-tank; a degasser connected to the second flow path and configured to degas the ink flowing into the second flow path; a third flow path through which the degassed ink flows to the printhead; and a fourth flow path. A fourth flow path connects the printhead and the sub-canister, through which the ink returns from the printhead to the sub-canister; a circulation pump is configured to apply pressure to the ink in the circulation flow path, which includes the sub-canister, the second flow path, the degasser, the third flow path, the printhead, and the fourth flow path, to generate an ink flow in the circulation flow path; and a damper is disposed in the fourth flow path to control pressure fluctuations applied to the printhead, wherein the degasser has an ink inlet and an ink outlet, and in the direction in which the ink is ejected from the nozzle array, the ink inlet is arranged closer to the printhead than the ink outlet.

[0011] The effects of the invention

[0012] According to this application, the degasser is positioned downstream of the sub-canister and closer to the printhead, thereby reducing the amount of ink in the flow path connecting the degasser and the printhead. Therefore, the time it takes for the degassed ink to reach the printhead is shortened, and the initial printing time from the non-printing state to the printing state can be further reduced. Furthermore, since the degasser is arranged in the direction in which ink is ejected from the nozzle array, with the ink inlet closer to the printhead than the ink outlet, ink path separation within the degasser is suppressed during ink filling, thus mitigating ink supply issues. Attached Figure Description

[0013] Figure 1 The control configuration of an inkjet recording apparatus according to one embodiment of this application is shown.

[0014] Figure 2 It is shown that it includes Figure 1 A perspective view of the printhead unit in an inkjet recording device.

[0015] Figure 3 It shows from Figure 2 A perspective view of the state of the printhead unit with the cover removed.

[0016] Figure 4 yes Figure 3The right-side view of the printhead unit in the image.

[0017] Figure 5 yes Figure 3 A bottom view of the printhead unit in the image. Detailed Implementation

[0018] The following is a detailed description of embodiments of this application based on the accompanying drawings. In the drawings used for the following description, some basic configurations may be omitted, and the dimensions and proportions of the parts shown may not be accurate. Figures 2 to 5 In the diagram, the front-back direction D1, the up-down direction D2, and the left-right direction D3 are shown in the respective figures.

[0019] Figure 1 The control configuration of an inkjet recording apparatus 1 according to one embodiment of this application is shown. For example... Figure 1 As shown, the inkjet recording device 1 is mainly equipped with a printhead unit 10 and an ink supply unit 50. The printhead unit 10 and the ink supply unit 50 are connected by a cable 90.

[0020] Printhead unit 10 includes a box-shaped printhead unit housing 100 (see details for specific shape). Figure 2 The printhead unit housing 100 includes a printhead 11 for ejecting ink, a degassing assembly 12 for degassing dissolved gases in the ink to be supplied to the printhead 11, a damper 13 for suppressing pressure fluctuations applied to the printhead 11, and a one-way valve 14.

[0021] The printhead 11 has a nozzle array 16 and an ink reservoir 17. Multiple nozzles 15 for ejecting ink are arranged vertically in the nozzle array 16. The ink reservoir 17 is connected to the nozzle array 16 and stores ink to be ejected from each nozzle 15. Since the nozzle array 16 in this embodiment consists of two arrays, an ink reservoir 17 is provided for each of the two nozzle arrays 16, for example. Each ink reservoir 17 has an ink inlet 11A at its bottom and an ink outlet 11B at its top. The number of nozzle arrays 16 is not limited to two arrays; it can be one, three, or more arrays. The number of ink reservoirs 17 should also be proportional to the number of nozzle arrays 16. Even with multiple arrays, one ink reservoir 17 can be used to supply ink. The number of ink inlets 11A and ink outlets 11B should also correspond to the number of ink reservoirs 17.

[0022] The nozzle protection cap 21 is detachably attached to the printhead 11 to protect the nozzle array 16 from external impacts and dust adhesion. In this embodiment, UV ink, such as ultraviolet-curable ink, is used as the ink to be ejected from the printhead 11. Therefore, when printing is not in progress, the nozzle protection cap 21 is attached to cover the area around the nozzle array 16 so that the UV ink is not exposed to external light, including ultraviolet light, through the nozzle array 16. UV ink has the characteristic that if it is exposed to air for a long time, oxygen and other gases in the air will dissolve in the ink. The more gases dissolved in the ink, the worse the print quality, and the longer the time required to degas the dissolved gases. For this reason, the nozzle protection cap 21 also functions to prevent the ink in the nozzle array 16 from contacting the air as much as possible when printing is not in progress.

[0023] The degassing assembly 12, for example, has multiple hollow fibers and removes dissolved gases from the ink by passing ink through each hollow fiber and depressurizing the pressure outside each hollow fiber. The method for removing dissolved gases from the ink is not limited to this; other methods can be used, such as passing ink through the outside of each hollow fiber and depressurizing the pressure inside each hollow fiber to remove dissolved gases. In short, any method that can remove dissolved gases from the ink can be used for the degassing assembly 12, but the degassing assembly 12 must be small enough to be accommodated within the printhead unit 10.

[0024] The ink supply unit 50 has a box-shaped ink supply unit housing 110 (specific shape not shown), which houses a main tank 51 for storing ink I, a sub-tank 52 for temporarily storing ink I supplied from the main tank 51, four pumps 60-63, two pressure gauges 64 and 65, two valves 66 and 67, three check valves 71-73, and a pump controller 80 that controls the drive of each pump 61-64.

[0025] The pump controller 80 is composed of, for example, a CPU, ROM, and RAM. The CPU controls each pump 60-63 and each valve 66, 67 by executing the pump control program stored in the ROM. The RAM stores data and calculation results while the pump control program is being executed.

[0026] The main tank 51 is, for example, composed of a bagged container (“bag”), which can be replaced with a new bag when the ink I in the bag is used up. The main tank 51 is connected to the sub-tank 52 via a first flow path 91 for supplying the ink I in the main tank 51 to the sub-tank 52. The first flow path 91 is provided with a supply pump 60 for performing the supply of ink I from the main tank 51 to the sub-tank 52 and a first one-way valve 71 for preventing backflow, which refers to ink I flowing in the opposite direction to the supply direction. The first flow path 91 is formed, for example, by a flexible tube. The second flow paths 92 to the fourth flow paths 94, described below, are also formed in the same manner as the first flow path 91, for example, by flexible tubes.

[0027] Sub-tank 52 is a tank used as described above for temporarily storing ink I supplied from main tank 51, and has a storage level detection sensor 53 for detecting the amount of ink I stored in sub-tank 52. The storage level detection sensor 53 is, for example, a float sensor, which outputs an ON signal when the ink I level in sub-tank 52 reaches a predetermined upper limit position and an OFF signal when the ink I level reaches a predetermined lower limit position. Once the storage level detection sensor 53 outputs an ON signal, it continuously outputs an ON signal until it outputs an OFF signal. Once the storage level detection sensor 53 outputs an OFF signal, it continuously outputs an OFF signal until it outputs an ON signal.

[0028] Therefore, when the detection signal output from the storage level detection sensor 53 switches from an OFF signal to an ON signal, the pump controller 80 can determine that the ink level I in the sub-tank 52 has reached the upper limit position, and when the detection signal output from the storage level detection sensor 53 switches from an ON signal to an OFF signal, the pump controller 80 can determine that the ink level I in the sub-tank 52 has reached the lower limit position. Therefore, when the pump controller 80 determines that the ink level I has reached the lower limit position, the pump controller 80 starts driving the supply pump 60, and when the pump controller 80 determines that the ink level I has reached the upper limit position, the pump controller 80 stops driving the supply pump 60, thereby controlling the storage level of ink I in the sub-tank 52 within the range between a predetermined upper limit and a predetermined lower limit.

[0029] Sub-can 52 is connected to the degassing assembly 12 in the printhead unit 10 via a second flow path 92 for supplying ink I to sub-can 52. One end of a positive pressure path 97 is connected to sub-can 52 to apply positive pressure to the interior of sub-can 52, and a solenoid valve 66 for sub-can 52 is connected to the other end of the positive pressure path 97. This solenoid valve 66 is referred to below as sub-can valve 66.

[0030] Sub-tank valve 66 switches between a closed and an open state in response to an ON / OFF signal from pump controller 80. Sub-tank valve 66, for example, is always open. When an ON signal is output from pump controller 80, sub-tank valve 66 switches to the closed state; when an OFF signal is output from pump controller 80, sub-tank valve 66 switches to the open state.

[0031] Air pump 61 and pressure gauge 64 are connected to positive pressure path 97. When inkjet recording device 1 receives a maintenance command, such as initial ink introduction or purging operation, air pump 61 pressurizes the interior of sub-tank 52 through positive pressure path 97 and supplies ink I from sub-tank 52 to printhead 11 through second flow path 92, degassing assembly 12, and third flow path 93. Pressure gauge 64 detects the pressure in sub-tank 52 through positive pressure path 97 and outputs the detection result to pump controller section 80. During initial ink introduction, pump controller 80 outputs an ON signal to sub-tank valve 66 to close sub-tank valve 66, and then drives air pump 61 and circulation pump 62. Then, pump controller 80 controls the drive of air pump 61 so that the pressure value in sub-tank 52 detected by pressure gauge 64 becomes a predetermined pressurization value. As a result, ink I is supplied from sub-tank 52 to printhead 11 at a predetermined flow rate via degassing assembly 12. Furthermore, air pump 61 and circulation pump 62 are driven until ink I flows from printhead 11 through damper 13 and fourth ink flow path 94 to sub-tank 52, after which air pump 61 and circulation pump 62 are shut off together with sub-tank valve 66. During the purge operation, pump controller 80 outputs an ON signal to sub-tank valve 66 while circulation pump 62 remains closed. Then, with sub-tank valve 66 closed, pump controller 80 controls the drive of air pump 61 so that the pressure value in sub-tank 52 detected by pressure gauge 64 becomes a predetermined pressure value. As a result, ink I is pressurized from sub-tank 52 to printhead 11 and forced out of nozzle array 16. After the purge operation, air pump 61 and sub-tank valve 66 are shut off.

[0032] The degassing assembly 12 is connected to the ink inlet 11A of the printhead 11 via a third flow path 93, and the degassed ink I flows through the third flow path 93. Since pressure needs to be reduced inside the degassing assembly 12 as described above, a negative pressure pump 63 is connected to the degassing assembly 12 via a negative pressure path 98. A pressure gauge 65, a solenoid valve 67, and a third check valve 73 are connected to the negative pressure path 98. The degassing assembly 12 and the negative pressure pump 63 constitute the degasser 30.

[0033] Solenoid valve 67 switches between an open and closed state in response to an ON / OFF signal from pump controller 80. Solenoid valve 67, for example, is always closed. When an ON signal is output from pump controller 80, solenoid valve 67 switches the valve to the open state; when an OFF signal is output from pump controller 80, solenoid valve 67 switches the valve to the closed state.

[0034] Pressure gauge 65 detects the pressure applied to degassing assembly 12 via negative pressure path 98 and outputs this value to pump controller 80. Pump controller 80 controls the drive of negative pressure pump 63 so that the pressure value detected by pressure gauge 65 reaches a predetermined negative pressure value. As described above, solenoid valve 67 is always closed unless pump controller 80 outputs an ON signal to solenoid valve 67. When the pressure value detected by pressure gauge 65 reaches the predetermined negative pressure value, pump controller 80 stops driving negative pressure pump 63. Third check valve 73 operates to maintain the negative pressure value in negative pressure path 98, thereby stopping the drive of negative pressure pump 63. When the negative pressure value in negative pressure path 98 drops to or below a predetermined threshold, pump controller 80 resumes driving negative pressure pump 63. Thus, during the degassing of ink I via degassing assembly 12, the negative pressure in negative pressure path 98 is controlled at a constant value.

[0035] The ink outlet 11B of the printhead 11 and the sub-tank 52 in the ink supply unit 50 are connected via a fourth flow path 94 to return the ink I flowing from the printhead 11 to the sub-tank 52. The fourth flow path 94 includes, in this order, a damper 13, a one-way valve 14, a circulation pump 62, and a second one-way valve 72 in the direction of ink I returning to the sub-tank 52. The sub-tank 52, the second flow path 92, the degassing assembly 12, the third flow path 93, the printhead 11, and the fourth flow path 94 form a circulation path for the ink I. The second flow path 92, the fourth flow path 94, and the negative pressure path 98 are connected to the printhead unit housing 100 and the ink supply unit housing 110 via the aforementioned cable 90. When the ink I stagnating in the circulation path contains a large amount of dissolved gas, for example, when ink I has not been ejected from the printhead 11 for a predetermined period of time, the pump controller 80 drives the circulation pump 62 to return the stagnant ink I in the circulation path to the sub-tank 52. At this time, by circulating the ink while driving the degasser 30, the ink in the printhead 11 is replaced by ink that has been properly degassed by the degassing assembly 12. Then, the ink I returning to the sub-tank 52, containing a large amount of dissolved gas, is also degassed by the degassing assembly 12. Therefore, when ink I is ejected from the printhead 11 and printed, appropriate ink is used. This makes it possible to suppress the deterioration of print quality while reducing the waste of ink I retained in the circulation path. The printhead unit housing 100 is an example of a "first housing", and the ink supply unit housing 110 is an example of a "second housing".

[0036] The control processes performed by the inkjet recording apparatus 1 configured as described above, particularly by the pump controller 80, will be described below as print-time processing and cycle-time processing, respectively. For simplicity, it is assumed that the inkjet recording apparatus 1 described below has completed the initial introduction of ink I. Here, print-time processing refers to the process of printing by ejecting ink I from the printhead 11 to the recording medium, and cycle-time processing refers to the process of circulating ink I in the aforementioned cycle path and returning ink I to the sub-tank 52. The trigger for initiating print-time processing can be, for example, a user instruction to start printing. On the other hand, the time for initiating cycle-time processing can be, for example, a predetermined time before initiating print-time processing. The predetermined time includes the time when the power to the inkjet recording apparatus 1 is turned on, the time when the user instructs to initiate cycle-time processing, and the time when predetermined conditions are met. The predetermined conditions include, as described above, the fact that a predetermined time period has elapsed since ink I was not ejected from the printhead 11. Therefore, even if the user instructs to start printing, if the aforementioned predetermined time is met, the pump controller 80 will not immediately start print-time processing, but will start print-time processing after the cycle-time processing is completed.

[0037] When printing begins, pump controller 80 starts driving negative pressure pump 63. At this time, solenoid valve 67 needs to be closed. Since solenoid valve 67 is always closed, pump controller 80 does not need to output any signal to solenoid valve 67. However, when an ON signal is output to solenoid valve 67 and solenoid valve 67 is in the open state, pump controller 80 needs to output an OFF signal to solenoid valve 67. Pump controller 80 continues to drive negative pressure pump 63 until pressure gauge 65 detects a predetermined negative pressure value, and when pressure gauge 65 detects the predetermined negative pressure value, pump controller 80 stops driving negative pressure pump 63.

[0038] Next, when there is no ink I stored in the sub-tank 52, the pump controller 80 starts driving the supply pump 60. Then, when the pump controller 80 detects that the signal output from the level detection sensor 53 has switched from an OFF signal to an ON signal, the pump controller 80 stops driving the supply pump 60. On the other hand, when ink I is stored in the sub-tank 52, the pump controller 80 controls the storage level of ink I in the sub-tank 52 within a range from a predetermined upper limit to a predetermined lower limit, as described above.

[0039] When a print command signal is received and the print head 11 is driven, ink I is ejected from each nozzle 15 forming the nozzle array 16 to perform printing. At this time, the damper 13 suppresses fluctuations in the pressure applied to the print head 11. During the printing process, the pump controller 80 controls the drive of the circulation pump 62 to a stopped state. The amount of ink consumed by driving the print head 11 is replenished from the sub-tank 52 through the second flow path 92 and the degassing assembly 12 using the negative pressure generated by ink consumption. Therefore, during the printing operation, the appropriate amount of ink is supplied through the degassing assembly 12 to obtain good print quality results.

[0040] On the other hand, when the cycle processing begins, the pump controller 80 starts driving the negative pressure pump 63 in the same manner as the process when printing begins. Then, the pump controller 80 continues to drive the negative pressure pump 63 until the pressure gauge 65 detects a predetermined negative pressure value, and when the pressure gauge 65 detects the predetermined negative pressure value, the pump controller 80 stops driving the negative pressure pump 63. At this time, as described above, the solenoid valve 67 is closed, and the third check valve 73 operates to maintain the negative pressure value in the negative pressure path 98 as described above, thereby maintaining the negative pressure path 98 at the predetermined negative pressure value.

[0041] Next, pump controller 80 starts driving circulation pump 62. Assuming ink I is stored in sub-tank 52, circulation pump 62 is driven to return ink I in the circulation path to sub-tank 52. Ink I containing dissolved gas remains in the third flow path 93 and ink storage section 17 in the circulation path. This is because during the printing process, as described above, ink I is not supplied to the fourth flow path 94 because circulation pump 62 is controlled to stop. Therefore, if ink I returns to sub-tank 52 in the amount in third flow path 93 and ink storage 17, third flow path 93 and ink storage 17 will be filled with degassed ink I by degassed component 12. However, considering error margin, up to 1.2 times the amount of ink I in third flow path 93 and ink storage 17 can be returned.

[0042] Therefore, when ink I, at a rate of 1 to 1.2 times the amount of ink I in the third flow path 93 and ink reservoir 17, returns to the sub-tank 52, the pump controller 80 stops driving the circulation pump 62. Here, the pump controller 80 can determine, for example, whether ink I, at a rate of 1 to 1.2 times the amount of ink I in the third flow path 93 and ink reservoir 17, has returned to the sub-tank 52 based on the driving time and / or number of rotations of the circulation pump 62. The pump controller 80, for example, controls the circulation pump 62 to flow ink I in the circulation path at a flow rate greater than 2 ml / min but less than 8 ml / min. The reason for flowing ink I at such a flow rate in the circulation path is to shorten the time it takes for ink I, after being sufficiently degassed by the degassing assembly 12, to fill the third flow path 93 and ink reservoir 17 within a range where the meniscus of the nozzle array 16 of the printhead 11 is not disrupted by pressure fluctuations caused by the pump 62.

[0043] Figure 2 The appearance of the printhead unit 10 is shown. (See diagram.) Figure 2 As shown, the printhead unit 10 has a rectangular printhead unit housing 100. The top, left, and right sides of the printhead unit housing 100 are covered by a cover portion 100A. The printhead 11 is disposed on the front surface of the printhead unit housing 100, and when printing is not performed, a nozzle protection cap 21 is attached to the printhead 11.

[0044] Figures 3 to 5 It shows from Figure 2 The printhead unit 10 in the middle has removed the cover portion 100A. Figure 3 It is a perspective view. Figure 4 This is the right-side view. Figure 5 It's a bottom view. (Refer to...) Figures 3 to 5 The following explains how the configuration included in the printhead unit 10 is arranged in the printhead unit housing 100.

[0045] The degassing assembly 12 and the damper 13 are arranged in the printhead unit housing 100 in a manner that avoids the printhead 11 in the direction in which the nozzle array 16 extends, i.e., in the vertical direction. In other words, the degassing assembly 12 and the damper 13 do not overlap with the printhead 11 when viewed from the front-back direction or from the left-right direction. Furthermore, the degassing assembly 12 and the damper 13 are arranged horizontally in the upper part of the printhead unit housing 100 inside the front-back direction. They are arranged in this way because the circuit board 40 stands upright at the bottom of the printhead unit housing 100, and it is necessary to avoid the circuit board 40.

[0046] Furthermore, since the connection terminals of the circuit board 40 and the printhead 11 are connected by a flexible cable (not shown) that transmits drive signals, the layout is designed to avoid interference with their wiring. This layout facilitates the assembly and maintenance of the printhead unit 10 and prevents contamination of the electrical system in the event of ink leakage from the ink flow path. Because the degassing assembly 12 is longer than the printhead 11, when the degassing assembly 12 is arranged vertically within the printhead unit 10, the height of the printhead unit housing 100 housing the degassing assembly 12 becomes significantly greater than the length of the nozzle array 16. This is undesirable as it restricts the environment in which the printhead unit 10 can be installed relative to the printing target. Therefore, to reduce the size of the printhead unit housing 100 in this embodiment, a damper 13, thin vertically and extending longitudinally, is arranged above and adjacent to the degassing assembly 12. This reduces the size of the printhead unit housing 100 in the lateral direction and makes the printhead unit 10 smaller.

[0047] The degassing assembly 12 has an ink inlet 12A, an ink outlet 12B, and a negative pressure supply port 12C. The ink inlet 12A is located at the bottom of the degassing assembly 12 and in front of the center portion in the front-rear direction. The ink outlet 12B is located at the rear of the degassing assembly 12. The printhead unit 10 is designed to print in a first printing mode or a second printing mode. In the first printing mode, it prints a vertically placed recording medium from the side, and in the second printing mode, it prints a horizontally placed recording medium from above.

[0048] When printing in the first printing mode, the print head unit 10, as Figure 2 The installation shown is such that the printhead unit 10 is mounted with its lower surface horizontal and prints on a recording medium facing the printhead 11. The ink inlet 12A is located at the lower part of the degassing assembly 12, and the ink outlet 12B is located at the rear of the degassing assembly 12, so that print quality is not degraded during printing in the first printing mode. In other words, with the ink inlet 12A located at the lower part of the degassing assembly 12, the ink I flowing into the degassing assembly 12 fills the degassing assembly 12 from the bottom, reaches the top, and flows out from the ink outlet 12B when the degassing assembly 12 is full. When the ink I flows out of the degassing assembly 12, the interior of the degassing assembly 12 is filled with ink I, and since no space is created, the path is not divided, and the fully degassed ink I is supplied from the degassing assembly 12 to the printhead 11. As a result, the fully degassed ink I is ejected from the printhead 11, thereby preventing degradation of print quality.

[0049] On the other hand, when printing in the second printing mode, the printhead unit 10 is mounted with its front surface horizontal and facing downwards to print on the recording medium facing the printhead 11. The ink inlet 12A is located in front of the central portion of the degassing assembly 12 in the longitudinal direction, and the ink outlet 12B is located at the rear of the degassing assembly 12 to prevent deterioration of print quality during printing in the second printing mode. In other words, with the ink inlet 12A located in front of the central portion in the longitudinal direction, the ink I flowing into the degassing assembly 12 fills the degassing assembly 12 from the front, reaches the rear, and flows out from the ink outlet 12B when the degassing assembly 12 is full. When the ink I flows out of the degassing assembly 12, the interior of the degassing assembly 12 is filled with ink I, and since no space is created, the path is not separated, and the fully degassed ink I is supplied from the degassing assembly 12 to the printhead 11. As a result, the fully degassed ink I is ejected from the printhead 11, thereby preventing deterioration of print quality.

[0050] Therefore, the ink inlet 12A is located at the lower part of the degassing assembly 12 and in front of the center portion in the front-rear direction, and the ink outlet 12B is located at the rear part of the degassing assembly 12, so that the degradation of print quality can be suppressed when printing in the first printing mode or the second printing mode.

[0051] The second flow path 92 connects to the ink inlet 12A, the third flow path 93 connects to the ink outlet 12B, and the negative pressure path 98 connects to the negative pressure supply port 12C. The third flow path 93 extends along the rear and bottom surfaces of the printhead unit housing 100 and splits into two flow paths 93A and 93B in the middle. One flow path 93A connects to the ink flow path 11A of one of the two nozzle rows 16, and the other flow path 93B connects to the other of the two nozzle rows 16. The length of the third flow path 93 should be shorter, and its flow path diameter should be smaller to the extent that it does not obstruct the supply of ink I for printing. This is because, as described above, during the circulation process, the amount of ink I containing dissolved gas and to be returned to the sub-tank 52 is reduced. In other words, if the amount of ink I containing dissolved gas and to be returned to the sub-tank 52 during the circulation process is small, the time from the start of the circulation process to the start of the printing process will be shorter. Therefore, a third flow path 93 with a path length of less than or equal to 500 mm and a flow path diameter of greater than or equal to 2 mm to less than or equal to 4 mm is preferably used. However, due to the disadvantages of the layout, the path length must reach the full length of the degassing component 12. Therefore, in this embodiment, the flow path length is, for example, 150 mm or longer.

[0052] As described above, the inkjet recording apparatus 1 of this embodiment includes: a printhead 11 having a nozzle array 16 for ejecting ink I; a main tank 51 for storing ink I; a first flow path 91 through which ink I flows from the main tank 51; a sub-tank 52 connected to the first flow path 91 and temporarily storing the ink I flowing through the first flow path 91; a second flow path 92 through which ink I flows from the sub-tank 52; a degassing device 30 connected to the second flow path 92 for degassing the ink I flowing into the second flow path 92; and a third flow path 93. The third flow path 93 supplies ink I, degassed by the degasser 30, to the printhead 11; the fourth flow path 94 connects the printhead 11 and the sub-tank 52, and supplies ink I from the printhead 11 back to the sub-tank 52; the circulation pump 62 applies pressure to the circulation path of ink I, including the sub-tank 52, the second flow path 92, the degasser 30, the third flow path 93, the printhead 11, and the fourth flow path 94, to generate an ink flow of ink I in the circulation path; and the damper 13 is disposed in the fourth flow path 94 to control pressure fluctuations applied to the printhead 11.

[0053] The degasser 30 has an ink inlet 12A and an ink outlet 12B. In the direction in which ink I is ejected from the nozzle array 16, the ink inlet 12A is arranged closer to the printhead 11 than the ink outlet 12B.

[0054] Therefore, in this inkjet recording apparatus 1, the degasser 30 is arranged downstream of the sub-tank, resulting in a small amount of ink in the flow path connecting the degasser 30 and the printhead 11. Consequently, the time it takes for the degassed ink I to reach the printhead 11 is shortened, and the initial printing time from the non-printing state to the printing state can be further shortened. The degasser 30 is arranged such that, in the direction of ink ejection from the nozzle array 16, the ink inlet 12A is closer to the printhead 11 than the ink outlet 12B. This suppresses the separation of ink paths within the degasser assembly 12 during ink filling, thereby alleviating ink supply problems.

[0055] The inkjet recording device 1 has a printhead unit housing 100 and an ink supply unit housing 110. A degassing unit 30 includes a degassing assembly 12 and a negative pressure pump 63. The degassing assembly 12 has an ink flow path through which the ink to be degassed flows, and the negative pressure pump 63 applies negative pressure to the degassing assembly 12. The printhead unit housing 100 houses the printhead 11, the degassing assembly 12, and the damper 13. The ink supply unit housing 110 houses the main tank 51, the sub-tank 52, the circulation pump 62, and the negative pressure pump 63. The printhead unit housing 100 and the ink supply unit housing 110 are connected by a cable 90 passing through a second flow path 92 and a fourth flow path 94.

[0056] Therefore, in this inkjet recording apparatus 1, the printhead 11, the degassing assembly 12, and the damper 13 are housed in the printhead unit housing 100, while the main tank 51, the sub-tank 52, the circulation pump 62, and the negative pressure pump 63 are housed in the ink supply unit housing 110. In other words, the ejection of ink I and the supply of ink I are performed by the printhead unit housing 100 and the ink supply unit housing 110, respectively, and the printhead 11 and the degassing assembly 12 are arranged closely together in the printhead unit housing 100. This shortens the time it takes for the degassed ink I to reach the printhead 11, thus enabling a further reduction in the initial printing time from the non-printing state to the printing state.

[0057] The degassing assembly 12 and the damper 13 are arranged in the printhead unit housing 100 in a manner that avoids the printhead 11 in the direction in which the nozzle array 16 extends, specifically in the vertical direction in this embodiment. As a result, the degassing assembly 12 and the damper 13 are arranged so as not to interfere with the flexible cable connecting the circuit board 40 and the signal lines driving the printhead 11. This makes the assembly and maintenance of the printhead unit 10 easier and prevents the electrical system from becoming contaminated in the event of events such as ink leakage from the ink flow path.

[0058] The degassing assembly 12 and the damper 13 are arranged within the printhead unit housing 100 adjacent to each other in the direction in which the nozzle array 16 extends, and in this embodiment, in the vertical direction. This allows the degassing assembly 12 and the damper 13 to be efficiently arranged within the space of the printhead unit housing 100 while avoiding the circuit board 40. As a result, the size of the printhead unit housing 100 in the lateral direction can be reduced, and the printhead unit 10 can be miniaturized.

[0059] The length of the third flow path 93 is 500 mm or less, and the diameter of the third flow path 93 is greater than or equal to 2 mm and less than or equal to 4 mm. By defining the length and diameter of the third flow path 93 in this way, the amount of ink I containing a large amount of dissolved gas that remains in the third flow path 93 can be limited. This allows for a reduction in the amount of ink I returning from the printhead 11 to the sub-tank 52.

[0060] The inkjet recording apparatus 1 also includes a pump controller 80 that controls the operation of the circulation pump 62 and the negative pressure pump 63. When the inkjet recording 1 is turned on or before recording operations are performed on the printhead 11, the pump controller 80 drives the negative pressure pump 63, and after negative pressure has been applied to the degassing assembly 12 via the negative pressure pump 63, it drives the circulation pump 62, causing a predetermined amount of ink I to flow in the circulation path. The pump controller 80 controls the circulation pump 62 to stop during the application of negative pressure to the degassing assembly 12 via the negative pressure pump 63.

[0061] Therefore, when the inkjet recording device 1 is turned on or before the printhead 11 performs a recording operation, only a predetermined amount of ink I flows in the circulation path, and during the recording operation of the printhead 11, no ink I flows in the circulation path. Thus, when it is necessary to return ink I from the printhead 11 to the sub-tank 52, a minimum amount of ink I can be allowed to flow in the circulation path.

[0062] The aforementioned predetermined amount is 1.0 to 1.2 times the total capacity of the third flow path 93 and the printhead 11. This allows a minimum amount of ink I to flow in the circulation path, even when ink I needs to be returned from the printhead 11 to the sub-tank 52.

[0063] The inkjet recording device 1 also includes a negative pressure path 98 connecting the negative pressure pump 63 and the degassing assembly 12, and a one-way valve in the negative pressure path 98. When the negative pressure applied by the negative pressure pump 63 to the negative pressure path 98 reaches the target pressure, the pump controller 80 controls the negative pressure pump 63 to stop. This allows the negative pressure pump 63 to remain in a stopped state for a period of time, thereby reducing power consumption.

[0064] The pump controller 80 drives the circulation pump 62 while applying negative pressure to the degassing assembly 12, causing the ink I to flow in the circulation path at a rate greater than 2 ml / min and less than 8 ml / min. This allows for the rapid supply of fully degassed ink to the printhead 11 without causing nozzle meniscus breakage or other problems, and allows printing operations to begin without requiring the user to wait.

[0065] This instruction is not limited to the above-described implementation method, but various modifications can be made without departing from its intent.

[0066] (1) In the above embodiment, the pump controller 80 is disposed inside the ink supply unit 50, but the pump controller 80 may be disposed outside the ink supply unit 50. In this case, the pump controller 80 may be a general-purpose device, such as a PC.

[0067] (2) In the above embodiment, the degassing component 12 and the damper 13 are arranged horizontally in the front-back direction on the upper part of the printhead unit housing 100. However, if the circuit board 40 is set to stand vertically on the upper part of the printhead unit housing 100, the degassing component 12 and the damper 13 can be arranged horizontally in the front-back direction on the lower part of the printhead unit housing 100.

[0068] (3) In the above embodiment, the pump controller 80 starts driving the negative pressure pump 63 when the printing process or the cycle process begins. The pump controller 80 can start driving the negative pressure pump 63 when the power of the inkjet recording device 1 is turned on, and can drive the negative pressure pump 63 as needed to maintain the negative pressure value in the negative pressure path 98 until the power is turned off.

[0069] Symbol Explanation

[0070] 1 Inkjet Recording Device

[0071] 11 printheads

[0072] 12 Degassing Components

[0073] 12A Ink Inlet

[0074] 12B ink export

[0075] 13 dampers

[0076] 14 Check Valves

[0077] 15 nozzles

[0078] 16-nozzle array

[0079] 17 Ink Storage

[0080] 30 degasser

[0081] 50 ink supply units

[0082] 51 Main Tank

[0083] 52 sub-cans

[0084] 53 Storage quantity detection sensor

[0085] 61 air pump

[0086] 62 circulating pump

[0087] 63 Negative Pressure Pump

[0088] 64 and 65 pressure gauges

[0089] 66 Sub-tank Valve

[0090] 67 Solenoid Valve

[0091] 71 First check valve

[0092] 72 Second check valve

[0093] 73 Third check valve

[0094] 80 Pump Controller

[0095] 90 cable

[0096] 91 first flow path

[0097] 92 Second Flow Path

[0098] 93 Third Flow

[0099] 94 Fourth Flow Path

[0100] 97 Positive Pressure Path

[0101] 98 Negative Pressure Path

[0102] 100 Printhead Unit Housing (First Housing)

[0103] 110 Ink Supply Unit Housing (Second Housing)

[0104] I. Ink.

Claims

1. An inkjet recording device, characterized in that, include: A printhead having a nozzle array configured to eject ink; Main container, configured to store the ink; A first flow path, through which the ink flows from the main tank; A sub-can, which is connected to the first flow path and is configured to temporarily store the ink flowing into the first flow path; A second flow path through which the ink flows from the sub-tank; A degasser, which is connected to the second flow path and configured to degas the ink flowing into the second flow path; A third flow path is provided for the ink, after being degassed by the degasser, to flow to the printhead; A fourth flow path connects the printhead and the sub-canister, through which the ink returns from the printhead to the sub-canister; A circulation pump configured to apply pressure to ink in a circulation path comprising the sub-tank, the second flow path, the degasser, the third flow path, the printhead, and the fourth flow path, to generate an ink flow in the circulation path; as well as A damper, disposed in the fourth flow path, controls pressure fluctuations applied to the printhead. The degassing device has an ink inlet and an ink outlet, and In the direction in which the ink is ejected from the nozzle array, the ink inlet is arranged closer to the printhead than the ink outlet.

2. The inkjet recording device according to claim 1, characterized in that, Also includes: First shell; as well as Second shell, The degassing device includes a degassing assembly and a negative pressure pump. The degassing assembly has a flow path through which the ink to be degassed flows, and the negative pressure pump is configured to apply negative pressure to the degassing assembly. The first housing houses the printhead, the degassing assembly, and the damper. The second housing accommodates the main tank, the sub-tank, the circulation pump, and the negative pressure pump, and The first housing and the second housing are interconnected by a cable, through which the second flow path and the fourth flow path pass.

3. The inkjet recording device according to claim 2, characterized in that, The degassing assembly and the damper are arranged in the first housing in a manner that avoids the printhead in the direction in which the nozzle column extends.

4. The inkjet recording device according to claim 3, characterized in that, The degassing assembly and the damper are arranged in the first housing adjacent to each other in the direction in which the nozzle array extends.

5. The inkjet recording device according to claim 1, characterized in that, The length of the third channel is less than or equal to 500 mm, and the diameter of the third channel is greater than or equal to 2 mm and less than or equal to 4 mm.

6. The inkjet recording apparatus according to any one of claims 2 to 4, characterized in that, It also includes a pump controller configured to control the drive of each of the circulating pump and the negative pressure pump. The pump controller is configured as follows: The negative pressure pump is driven when the inkjet recording device is turned on or before a recording operation is performed through the printhead; After the negative pressure pump has applied negative pressure to the degassing assembly, the circulation pump is driven, causing a predetermined amount of ink to flow in the circulation path; and During the recording operation via the printhead, the circulation pump is stopped while negative pressure is applied to the degassing assembly via the negative pressure pump.

7. The inkjet recording apparatus according to claim 6, characterized in that, The predetermined amount is an ink volume that is 1.0 to 1.2 times the total capacity of the third flow path and the printhead.

8. The inkjet recording apparatus according to claim 6, characterized in that, Also includes: A negative pressure path, connecting the negative pressure pump and the degassing assembly; and A one-way valve is provided in the negative pressure path. The pump controller is configured to stop the negative pressure pump when the negative pressure supplied to the negative pressure path by the negative pressure pump reaches the target pressure.

9. The inkjet recording apparatus according to claim 6, characterized in that, The pump controller is configured to control the drive of the circulation pump when the negative pressure is applied to the degassing assembly, such that the ink flows in the circulation path at a flow rate greater than 2 ml / min and less than 8 ml / min.

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