Ink jet recording device

Abstract

To provide an ink jet recording device preventing a negative pressure adjustment valve from being damaged even when compression purge processing is executed, and capable of stably executing ink discharge from a recording head.SOLUTION: An ink jet recording device includes an ink container, a recording head, an ink channel, a negative pressure adjustment valve, a pressurization pump, a cap, a suction pump and a waist ink discharge channel. The ink channel includes: an ink inflow passage communicated from the ink container to the negative pressure adjustment valve via the pressurization pump; an ink outflow passage communicated from the negative pressure adjustment valve to the recording head; a bypass passage communicated from a downstream side from the pressurization pump of the ink inflow passage to the recording head without via the negative pressure adjustment valve; a relief passage communicated from the ink container to the ink outflow passage without via the pressurization pump and the negative pressure adjustment valve; an opening / closing valve for opening / closing the bypass passage; and a nonreturn valve disposed in the ink relief passage and circulating ink only in a direction from the ink outflow passage to the ink container.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present invention relates to an inkjet recording apparatus equipped with a negative pressure adjustment valve. [Background technology]

[0002] In inkjet recording devices, it is important to maintain constant ink ejection conditions and ejection states in order to ensure high print quality. To address this issue, a pressure adjustment unit (negative pressure adjustment valve, damper, etc.) is installed in the ink flow path connecting the ink container and the recording head to store ink and adjust the pressure.

[0003] However, when the pressure of the liquid supplied to the print head is kept constant by the negative pressure adjustment valve, if a pressure purge process (pressure cleaning) is performed in which a pressure pump is used to forcibly supply liquid from the ink container side, excessive pressure is applied to the negative pressure adjustment valve, causing it to be damaged. Therefore, there is a problem in that a suction purge process (suction cleaning) must be performed in which a suction pump is used to suck the liquid from the print head side.

[0004] Therefore, a method has been proposed that enables pressurized purging in a flow path configuration that uses a negative pressure adjustment valve. For example, Patent Document 1 discloses a method that includes a pump that can pressure-feed liquid to the ejection head, an on-off valve that is provided in a liquid flow path between a liquid storage unit and the ejection head and that opens when the pressure of the liquid between the liquid storage unit and the ejection head drops, and a bypass passage that connects the upstream side and downstream side of the on-off valve in the liquid flow path. and a liquid ejection apparatus which supplies pressurized liquid to the ejection head using a bypass flow path when performing pressure cleaning.

[0005] Patent Document 2 discloses a liquid ejection head including a first chamber communicating with a liquid container, a second chamber disposed downstream of the first chamber in the liquid supply direction and communicating with a liquid ejection head, and a separator separating the first chamber from the second chamber. the tank portion having a wall portion including a communication port that connects the first chamber and the second chamber to each other; an open / close member that is disposed at the communication port and changes its position between a closed position that closes the communication port and an open position that opens the communication port; a pump portion that is capable of performing a negative pressure generating operation to create a negative pressure in the second chamber so that liquid is supplied from the first chamber to the second chamber through the communication port in accordance with a decrease in liquid in the second chamber at least during a jetting operation in which the liquid jet head jets liquid onto a medium; and a bypass pipe that connects the tank portion and the pump portion to create a negative pressure in the second chamber. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Japanese Patent Application Laid-Open No. 2014-24347 [Patent Document 2] Japanese Patent Application Publication No. 2019-166782 Summary of the Invention [Problem to be solved by the invention]

[0007] In the configuration of Patent Document 1, when pressurized liquid is simply supplied to the ejection head using the bypass flow path, the same pressure as that applied to the ejection head is also applied to the outlet side of the negative pressure adjustment valve, which may result in damage to the negative pressure adjustment valve.

[0008] In the configuration of Patent Document 2, a check valve (backflow prevention mechanism) is provided in the outlet flow path of a negative pressure adjustment valve (liquid supply unit) with a bypass flow path, so that pressure is not applied to the negative pressure adjustment valve when pressure purging is performed. With this configuration, the flow path resistance increases during normal ejection, so when the ejection flow rate increases, the meniscus pressure of the nozzle decreases, which could result in ejection defects.

[0009] SUMMARY OF THE INVENTION In view of the above problems, an object of the present invention is to provide an inkjet recording apparatus in which a negative pressure adjusting valve is not damaged even when a pressurized purge process is performed, and in which ink can be stably ejected from the recording head. [Means for solving the problem]

[0010] To achieve the above object, a first aspect of the present invention is an inkjet recording device comprising an ink container, one or more recording heads, an ink flow path, a negative pressure adjustment valve, a pressure pump, a cap, a suction pump, and a waste ink discharge flow path. The ink container contains ink. The recording head has a plurality of nozzles for ejecting ink. The ink flow path connects the ink container to the recording head. The negative pressure adjustment valve is connected to the ink flow path. The pressure pump is connected to the ink flow path between the ink container and the negative pressure adjustment valve and sends ink to the negative pressure adjustment valve. The cap is attached to the ink discharge surface of the recording head and is capable of forming a sealed space between the cap and the ink discharge surface. The suction pump sucks air inside the cap. The waste ink discharge flow path discharges liquid sucked into the cap by the suction pump. The ink flow path has an ink inlet path, an ink outlet path, a bypass path, a relief path, an on-off valve, and a check valve. The ink inlet path connects from the ink container to the negative pressure adjustment valve via the pressure pump. The ink outlet path communicates with the recording head from the negative pressure adjustment valve. The bypass path communicates with the recording head from a downstream side of the pressure pump in the ink inlet path in the ink flow direction, without passing through the negative pressure adjustment valve. The relief path communicates with the ink outlet path from the ink container, without passing through the pressure pump and the negative pressure adjustment valve. The on-off valve opens and closes the bypass path. The check valve is provided in the relief path and allows ink to flow only in the direction from the ink outlet path toward the ink container. The inkjet recording device, with a cap attached to the ink ejection surface, can perform a suction purge process in which a suction pump sucks air from within a sealed space to forcibly discharge ink from all nozzles of the recording head, and a pressure purge process in which a pressure pump sends ink to the recording head to forcibly discharge ink from all nozzles of the recording head. [Effects of the Invention]

[0011] According to the first configuration of the present invention, when a pressure equal to or greater than a certain level is applied to the negative pressure adjustment valve during the pressurized purge process, ink flowing out of the outlet pressure chamber of the negative pressure adjustment valve passes through the check valve in the relief flow path and flows toward the ink container. This limits the upper limit of the pressure applied to the negative pressure adjustment valve, thereby preventing deterioration and damage to the negative pressure adjustment valve. Furthermore, since there is no need to provide a check valve in the ink inflow path between the pressure pump and the negative pressure adjustment valve, an increase in flow path resistance in the ink flow path during normal ink ejection can be suppressed. As a result, ejection defects caused by a decrease in meniscus pressure in the nozzle can also be suppressed. [Brief explanation of the drawings]

[0012] [Figure 1] FIG. 1 is an explanatory diagram showing the general configuration of a printer 100 as an inkjet recording apparatus according to an embodiment of the present invention. [Figure 2] A plan view of the recording unit 9 included in the printer 100. [Figure 3] 1 is a schematic diagram showing the arrangement of an ink flow path 40, an ink container 30 connected to the ink flow path 40, a negative pressure adjustment valve 31, and a recording head 17. [Figure 4] Side cross-sectional view of negative pressure adjustment valve 31 [Figure 5] FIG. 10 is a diagram showing the flow of liquid in the ink flow path 40 when a suction purge process is performed. [Figure 6] FIG. 10 is a diagram showing the flow of liquid in the ink flow path 40 when a pressure purge process is performed. DETAILED DESCRIPTION OF THE INVENTION

[0013] 1. Configuration of Inkjet Recording Apparatus Hereinafter, an embodiment of the present invention will be described with reference to the drawings. Fig. 1 is an explanatory diagram showing the general configuration of a printer 100 as an inkjet recording device according to an embodiment of the present invention. The printer 100 is equipped with a paper feed cassette 2, which is a paper storage unit. The paper feed cassette 2 is located at the bottom inside the printer main body 1. Inside the paper feed cassette 2, paper P, which is an example of a recording medium, is stored.

[0014] A paper feed device 3 is disposed downstream in the paper transport direction of the paper feed cassette 2, i.e., above the right side of the paper feed cassette 2 in Fig. 1. The paper feed device 3 separates and feeds the paper P one sheet at a time toward the upper right of the paper feed cassette 2 in Fig. 1.

[0015] The printer 100 is equipped with a first paper transport path 4a inside. The first paper transport path 4a is located in the upper right corner, in the paper feed direction, of the paper feed cassette 2. Paper P sent out from the paper feed cassette 2 is transported vertically upward along the side of the printer body 1 by the first paper transport path 4a.

[0016] A pair of registration rollers 13 is provided at the downstream end of the first paper transport path 4a in the paper transport direction. Furthermore, a first transport unit 5 and a recording unit 9 are arranged immediately downstream in the paper transport direction of the pair of registration rollers 13. The paper P sent out from the paper feed cassette 2 passes through the first paper transport path 4a and reaches the pair of registration rollers 13. The pair of registration rollers 13 corrects skewed feed of the paper P and sends the paper P toward the first transport unit 5 (particularly the first transport belt 8, which will be described later) in time with the ink ejection operation performed by the recording unit 9.

[0017] 2 is a plan view of the recording unit 9. The recording unit 9 includes a head housing 10 and line heads 11Y, 11M, 11C, and 11K. The line heads 11Y to 11K are held in the head housing 10 at a height that forms a predetermined gap (for example, 1 mm) with respect to the conveyance surface of an endless first conveyor belt 8 that is stretched over multiple rollers including a drive roller 6a, a driven roller 6b, and a tension roller (not shown). The drive roller 6a causes the first conveyor belt 8 to travel in the conveyance direction of the paper P (the direction of arrow A).

[0018] Each of the line heads 11Y to 11K has a plurality of (three in this example) recording heads 17a to 17c. The recording heads 17a to 17c are arranged in a staggered pattern along the paper width direction (arrow BB' direction), which is perpendicular to the paper transport direction (arrow A direction). Each of the recording heads 17a to 17c has a plurality of ink ejection orifices 18 (nozzles). The ink ejection orifices 18 are arranged at equal intervals along the width direction of the recording head, i.e., the paper width direction (arrow BB' direction). From the line heads 11Y to 11K, inks of yellow (Y), magenta (M), cyan (C), and black (K) are ejected via the ink ejection orifices 18 of the recording heads 17a to 17c toward the paper P transported by the first transport belt 8.

[0019] Four colors of ink (yellow, magenta, cyan, and black) are supplied to the recording heads 17a to 17c constituting each of the line heads 11C to 11K from ink containers 30 (see FIG. 1). A negative pressure adjustment valve 31 (see FIG. 1) is connected between the ink containers 30 and the recording heads 17a to 17c. The detailed configuration of the negative pressure adjustment valve 31 will be described later.

[0020] In response to a control signal from the control device 110 (see FIG. 1), each of the recording heads 17a to 17c ejects ink from the ink ejection openings 18 toward the paper P, which is adsorbed and held on the conveying surface of the first conveyor belt 8 and conveyed, in accordance with image data received from an external computer. As a result, a color image is formed on the paper P on the first conveyor belt 8, with inks of four colors, yellow, magenta, cyan, and black, superimposed on top of each other.

[0021] Returning to FIG. 1, the paper P sent to the first transport unit 5 by the pair of registration rollers 13 is transported by the first transport belt 8 to a position facing the recording unit 9 (particularly recording heads 17a to 17c, which will be described later). Ink is ejected from the recording unit 9 onto the paper P, thereby recording an image on the paper P. The ejection of ink in the recording unit 9 is controlled by a control device 110 inside the printer 100.

[0022] In the paper transport direction, a second transport unit 12 is disposed downstream of the first transport unit 5 (on the left side in FIG. 1). The paper P on which an image has been recorded by the recording unit 9 is sent to the second transport unit 12. The ink ejected onto the surface of the paper P is dried while passing through the second transport unit 12.

[0023] In the paper transport direction, a decurler unit 14 is provided downstream of the second transport unit 12 and near the left side of the printer body 1. The paper P from which the ink has been dried by the second transport unit 12 is sent to the decurler unit 14, where any curl that has occurred in the paper P is straightened.

[0024] In the paper transport direction, a second paper transport path 4b is provided downstream (upper in FIG. 1) of the decurler unit 14. If double-sided recording is not performed, the paper P that has passed through the decurler unit 14 passes through the second paper transport path 4b and is discharged to a paper discharge tray 15 provided outside the left side of the printer 100.

[0025] In addition, a maintenance unit 19 and a cap unit 20 are disposed below the second transport unit 12. When performing purging, the maintenance unit 19 moves horizontally below the recording unit 9, wipes off ink discharged from the ink discharge ports 18 of the recording heads 17a to 17c, and collects the wiped ink. Purging refers to the operation of forcibly discharging ink from the ink discharge ports 18 of the recording heads 17a to 17c in order to expel thickened ink, foreign matter, and air bubbles from the ink discharge ports 18. When capping the ink discharge surfaces of the recording heads 17a to 17c, the cap unit 20 moves horizontally below the recording unit 9, and then moves further upward to be attached to the undersides of the recording heads 17a to 17c.

[0026] 2. Configuration of ink flow path including negative pressure adjustment valve 3 is a schematic diagram showing the arrangement of an ink flow path 40, an ink container 30 connected to the ink flow path 40, a negative pressure adjustment valve 31, and a recording head 17. In the following description, the recording heads 17a to 17c will be simply referred to as the recording head 17. The up and down direction in FIGS. 3 and 4 to 6 corresponds to the vertical direction (the direction of gravity). The ink flow path 40 has an ink inlet path 41, an ink outlet path 42, a bypass path 43, and a relief path 60.

[0027] The negative pressure adjustment valve 31 is connected between the ink inflow channel 41 and the ink outflow channel 42. The ink inflow channel 41 communicates with an inflow pressure chamber 50 (see FIG. 4) of the negative pressure adjustment valve 31 from the ink container 30 via a pressure pump 33. The ink outflow channel 42 communicates with an outflow pressure chamber 51 (see FIG. 4) of the negative pressure adjustment valve 31 from the recording head 17.

[0028] A pressure pump 33 is connected to the ink inflow path 41. The pressure pump 33 maintains the internal pressure of the inflow pressure chamber 50 (see FIG. 4) of the negative pressure adjustment valve 31 at a constant pressure higher than the internal pressure of the outflow pressure chamber 51 (see FIG. 4). The pressure pump 33 is also used when performing a pressure purge process to forcibly push ink (or initial filling liquid) out of the ink ejection ports 18 of the recording head 17.

[0029] The bypass flow path 43 communicates with the recording head 17 from the ink inflow path 41 downstream of the pressure pump 33 without passing through the negative pressure adjustment valve 31. An open / close valve 44 is arranged in the bypass flow path 43.

[0030] Normally, the on-off valve 44 is closed, and therefore ink introduced from the ink container 30 into the ink flow path 40 passes through the ink inflow path 41, the negative pressure adjustment valve 31, and the ink outflow path 42 and is supplied to the recording head 17. When the on-off valve 44 is open, a flow of ink also occurs, passing from the ink inflow path 41 through the bypass path 43 and being supplied to the recording head 17.

[0031] The relief flow path 60 communicates with the ink outflow path 42 from the ink container 30 without passing through the pressure pump 33 and the negative pressure adjustment valve 31. A check valve 61 is provided in the relief flow path 60. The check valve 61 allows the flow of ink from the ink outflow path 42 toward the ink container 30, and regulates the flow of ink from the ink container 30 toward the ink outflow path 42.

[0032] A cap 201 is attached to the recording head 17. The cap 201 is supported by a cap unit 20 (see FIG. 1) and is attached to the ink ejection surface (nozzle surface) 171 of the recording head 17 when printing processing is not performed for a certain period of time or more. By attaching the cap 201, the ink ejection surface 171 of the recording head 17 is kept sealed. The cap 201 is provided with a flow path (not shown) that communicates with the atmosphere. This flow path can be opened and closed, and prevents excessive pressure changes from occurring in the nozzles of the recording head due to temperature changes in the space between the ink ejection surface 171 and the cap 201. A suction pump 45 and a waste ink discharge flow path 47 are connected to the cap 201.

[0033] In the printer 100, in order to remove dried or thickened ink and foreign matter from inside the ink ejection ports 18 (see FIG. 2) of the recording head 17, when starting printing after a long period of inactivity or between printing operations, a cap 201 is attached to the ink ejection surface 171, and with the flow path communicating with the atmosphere closed, a suction purge process is performed in which the air is sucked from the space (sealed space) between the ink ejection surface 171 and the cap 201 using the suction pump 45 to forcibly suck ink from all of the ink ejection ports 18 of the recording head 17, in preparation for the next printing operation. The ink sucked into the cap 201 from the recording head 17 (purged ink) is discharged outside the cap 201 by the suction pump 45 and then collected in a waste ink tank (not shown) via a waste ink discharge flow path 47.

[0034] The suction purge process is also performed when initially filling the ink flow path 40 with initial filling liquid or ink, when replacing the ink flow path 40 filled with initial filling liquid with ink, and when discharging air or foreign matter from the ink flow path 40.

[0035] [3. Configuration of the negative pressure adjustment valve] 4 is a side cross-sectional view of the negative pressure adjustment valve 31 used in the printer 100 of this embodiment. The negative pressure adjustment valve 31 stores ink flowing through the ink flow path 40 and functions as a pressure adjustment valve that opens and closes the ink flow path 40 in accordance with the pressure on the recording head 17 side. The negative pressure adjustment valve 31 has an inlet pressure chamber 50, an outlet pressure chamber 51, a valve member 52, and an opening / closing pressure adjustment spring 53.

[0036] The inlet pressure chamber 50 is connected to the ink inlet channel 41 (see FIG. 3). The inlet pressure chamber 50 has a predetermined volume for storing ink that has flowed in from the ink inlet channel 41. The inlet pressure chamber 50 is connected to the outlet pressure chamber 51 by a communication hole 54. The inlet pressure chamber 50 contains one end (large diameter portion) of a valve member 52 that can close the communication hole 54, and an opening / closing pressure adjustment spring 53.

[0037] The outflow pressure chamber 51 has an outflow hole 51a to which the ink outflow path 42 is connected, a diaphragm portion 55, and a pressure-receiving plate 56. The outflow pressure chamber 51 stores the ink that flows in from the communication hole 54. The volume of the outflow pressure chamber 51 changes depending on the diaphragm portion 55.

[0038] The outlet hole 51a is connected to the recording head 17 via the ink outlet path 42. The outlet hole 51a is formed at a higher position than the communication hole 54. In this embodiment, the first outlet hole 51a is formed at the upper end of the outlet-side pressure chamber 51. The outlet hole 51a may also be formed at a lower position than the communication hole 54, for example, at the lower end of the outlet-side pressure chamber 51.

[0039] The diaphragm portion 55 is formed from a laminated flexible resin film. The diaphragm portion 55 is fixed to the outer surface of the outlet pressure chamber 51 with a predetermined amount of slack. The diaphragm portion 55 displaces in response to pressure changes within the outlet pressure chamber 51, changing the volume of the outlet pressure chamber 51.

[0040] The pressure plate 56 is fixed to the inner surface of the diaphragm portion 55 (the resin layer facing the outlet-side pressure chamber 51) and is movable integrally with the diaphragm portion 55. The other end (small diameter portion) of the valve member 52 inserted into the communication hole 54 abuts against the pressure plate 56. A force acts on the pressure plate 56 by the biasing force of the opening / closing pressure adjusting spring 53 via the valve member 52 in a direction that displaces (expands) the diaphragm portion 55 outward.

[0041] 4 shows the negative pressure adjustment valve 31 in a state where ink is normally supplied from the ink container 30 to the recording head 17. When the recording head 17 is filled with ink, the pressure in the outlet pressure chamber 51 is maintained constant, and the communication hole 54 is closed by the valve member 52. Therefore, no ink is supplied from the inlet pressure chamber 50 to the outlet pressure chamber 51.

[0042] As ink is consumed in the recording head 17 and the pressure in the outlet pressure chamber 51 decreases, the diaphragm portion 55 is displaced inward (contracts). This causes the pressure-receiving plate 56 to press the valve member 52 into the inlet pressure chamber 50 (open position) against the biasing force of the opening / closing pressure adjustment spring 53, opening the communication hole 54. As a result, ink is supplied from the inlet pressure chamber 50 to the outlet pressure chamber 51. When the inside of the outlet pressure chamber 51 reaches a predetermined negative pressure, the biasing force of the opening / closing pressure adjustment spring 53 pushes the valve member 52 back into the outlet pressure chamber 51 (closed position), closing the communication hole 54 and stopping the supply of ink from the inlet pressure chamber 50 to the outlet pressure chamber 51. In this way, the pressure of ink supplied to the recording head 17 is adjusted.

[0043] 4. Flow of Liquid in Ink Flow Channels During Suction Purge Process and Pressure Purge Process 5 is a diagram showing the flow of liquid in the ink flow path 40 when a suction purge process is performed. As shown in FIG. 5, when a suction purge process is performed, the on-off valve 44 of the bypass flow path 43 is closed. Then, the ink ejection surface 171 of the recording head 17 is covered with a cap 201, and a suction pump 45 is used to suck the space between the ink ejection surface 171 and the cap 201 (a sealed space can be formed by closing the flow path that connects the inside of the cap 201 to the atmosphere), generating a negative pressure. This causes the liquid (ink or initial filling liquid) in the recording head 17 to be discharged from the ink ejection ports 18.

[0044] At this time, the outlet pressure chamber 51 in the negative pressure adjustment valve 31 becomes negative pressure, and the valve member 52 is pressed by the diaphragm portion 55. As a result, the valve member 52 moves into the inlet pressure chamber 50 against the biasing force of the opening / closing pressure adjustment spring 53, opening the communication hole 54 and connecting the inlet pressure chamber 50 to the outlet pressure chamber 51. This allows liquid to flow from the ink container 30 through the ink inlet channel 41, the negative pressure adjustment valve 31, and the ink outlet channel 42 to the recording head 17.

[0045] 6 is a diagram showing the flow of liquid in the ink flow path 40 when a pressure purge process is performed. As shown in FIG. 6, when a pressure purge process is performed, the on-off valve 44 of the bypass flow path 43 is opened. When ink is supplied from the ink container 30 by the pressure pump 33, some of the ink flows into the ink outlet path 42 via the ink inlet path 41 and the negative pressure adjustment valve 31. In addition, some of the ink passes through the bypass flow path 43 and flows into the ink outlet path 42, thereby preventing excessive pressure from being applied to the inlet pressure chamber 51 of the negative pressure adjustment valve 31.

[0046] However, the ink pressure generated by the pressure pump 33 is applied equally to the inlet pressure chamber 51 of the negative pressure adjustment valve 31 and the bypass flow path 43. Therefore, if the pressure applied to the negative pressure adjustment valve 31 exceeds the upper limit, there is a risk that the negative pressure adjustment valve 31 will deteriorate or be damaged.

[0047] Therefore, in this embodiment, a relief flow path 60 is provided that communicates with the ink outflow path 42 from the ink container 30 without passing through the pressure pump 33 and the negative pressure adjustment valve 31. The relief flow path 60 is provided with a check valve 61 that allows ink to flow only in the direction from the ink outflow path 42 toward the ink container 30.

[0048] According to the configuration of this embodiment, when a pressure equal to or greater than a certain level is applied to the negative pressure adjustment valve 31 during the pressurized purge process, ink flows out of the outlet pressure chamber 50 of the negative pressure adjustment valve 31 through the check valve 61 of the relief flow path 60 and flows toward the ink container 30. This makes it possible to regulate the upper limit of the pressure applied to the negative pressure adjustment valve 31, and to prevent deterioration or damage to the negative pressure adjustment valve 31.

[0049] Furthermore, since there is no need to provide a check valve in the ink inflow path 41 between the pressure pump 33 and the negative pressure adjustment valve 31, it is possible to suppress an increase in the flow path resistance of the ink flow path 40 during normal ink ejection. As a result, it is also possible to suppress ejection defects caused by a decrease in meniscus pressure inside the ink ejection port 18. The upper limit of the pressure applied to the negative pressure adjustment valve 31 can be adjusted by adjusting the regulated pressure by the check valve 61.

[0050] Furthermore, the present invention is not limited to the above-described embodiment, and various modifications are possible without departing from the spirit of the present invention. For example, in the above-described embodiment, the recording head 17, the negative pressure adjustment valve 31, the pressure pump 33, and the suction pump 45 are exemplified as components connected to the ink flow path 40, but the present invention is also applicable to a configuration in which other components are connected to the ink flow path 40.

[0051] In addition, in the above embodiment, an example was described in which a color printer that records color images using four colors of ink was used as the inkjet recording device, but the ink supply unit of this embodiment can also be used when a monochrome printer that records monochrome images using black ink is used. [Industrial Applicability]

[0052] The present invention can be used in inkjet recording devices such as inkjet printers that are equipped with a negative pressure adjustment valve connected between a liquid storage unit such as an ink container and a liquid ejection unit such as a recording head. [Explanation of symbols]

[0053] 17, 17a to 17c recording head 18 Ink outlet (nozzle) 30 Ink Container 31 Negative pressure adjustment valve 33 Pressure pump 40 Ink flow path 41 Ink inlet 42 Ink outflow path 43 Bypass flow path 44 On-off valve 45 Suction Pump 47 Waste ink discharge flow path 50 inlet pressure chamber 51 Outlet pressure chamber 52 Valve member 53 Opening / closing pressure adjustment spring (biasing member) 54 Communication hole 55 Diaphragm part 56 Pressure plate 60 Relief channel 61 Check valve 100 Printers (inkjet recording devices)

Claims

1. an ink container for storing ink; one or more recording heads each having a plurality of nozzles for ejecting the ink; an ink flow path that connects the ink container and the recording head; a negative pressure adjustment valve connected to the ink flow path; a pressure pump connected to the ink flow path between the ink container and the negative pressure adjustment valve, the pressure pump feeding the ink to the negative pressure adjustment valve; a cap that is attached to the ink ejection surface of the recording head and that can form a sealed space between the cap and the ink ejection surface; a suction pump that sucks air from inside the cap; a waste ink discharge flow path that discharges the liquid sucked into the inside of the cap by the suction pump; An inkjet recording apparatus comprising: The ink flow path is an ink inflow passage communicating with the negative pressure adjustment valve from the ink container via the pressure pump; an ink outflow path communicating from the negative pressure adjustment valve to the recording head; a bypass flow path that communicates with the recording head from a downstream side of the pressure pump of the ink inflow path in a flow direction of the ink without passing through the negative pressure adjustment valve; a relief flow path that communicates with the ink outflow path from the ink container without passing through the pressure pump and the negative pressure adjustment valve; an on-off valve that opens and closes the bypass flow path; a check valve provided in the relief flow path, allowing the ink to flow only in a direction from the ink outflow path toward the ink container; and a suction purge process in which, with the cap attached to the ink ejection surface, the air in the sealed space is sucked by the suction pump to forcibly discharge the ink from all the nozzles of the recording head; a pressure purge process in which the ink is forcibly discharged from all the nozzles of the recording head by sending the ink to the recording head using the pressure pump; An inkjet recording apparatus characterized in that it is capable of executing the above.

2. 2. The ink jet recording apparatus according to claim 1, wherein the on-off valve is closed when the suction purge process is performed, and the on-off valve is opened when the pressure purge process is performed.

3. 2. The inkjet recording apparatus according to claim 1, wherein the check valve allows the ink to flow only when a pressure equal to or greater than a certain level is applied to the negative pressure adjusting valve by the pressure pump during execution of the pressure purge process.

4. The negative pressure regulating valve is an inlet pressure chamber communicating with the ink inlet channel; an outflow pressure chamber communicating with the ink outflow channel; a communication hole that communicates the inlet pressure chamber with the outlet pressure chamber; a valve member that is inserted into the communication hole and that is movable between a closing position where the communication hole is closed and an opening position where the communication hole is opened in response to a pressure change in the outlet pressure chamber; 2. The inkjet recording apparatus according to claim 1, further comprising:

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