Negative pressure regulating valve and inkjet recording apparatus including the same

Abstract

To provide a negative pressure regulating valve capable of suppressing retention of bubbles and liquid having a large specific gravity in a pressure chamber by a simple configuration, and to provide an inkjet recording apparatus including the same.SOLUTION: The negative pressure regulating valve includes a pressure chamber, a valve member, a diaphragm portion, a pressure receiving plate, and a biasing member. The pressure chamber includes a liquid inflow port and a liquid outflow port formed above the liquid inflow port. The diaphragm portion is displaced inwardly and outwardly of the pressure chamber in accordance with a change in pressure in the pressure chamber. The pressure receiving plate changes the volume of the pressure chamber by being displaced to the inside and the outside of the pressure chamber together with the diaphragm portion. The valve member moves to the closed position and the open position together with the pressure receiving plate by the displacement of the diaphragm portion to the inside of the pressure chamber and the displacement of the pressure receiving plate to the outside of the pressure chamber by the biasing force of the biasing member. When the pressure receiving plate is displaced inward and outward of the pressure chamber, the amount of change in the volume of the pressure chamber increases from the upper side to the lower side of the pressure chamber with respect to the direction of gravity.SELECTED DRAWING: Figure 4

Description

[Technical Field]

[0001] The present invention relates to a negative pressure adjusting valve to be mounted on an inkjet recording apparatus, and to an inkjet recording apparatus equipped with the same. [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] Patent Document 1 discloses a liquid storage mechanism (negative pressure adjustment valve) that is provided between a liquid supply unit on the device main body and an inkjet printhead, and that includes a pressure chamber that stores liquid to be supplied to the inkjet printhead, with the pressure chamber having a liquid supply port and a liquid outlet located higher than the bottom of the pressure chamber. The liquid storage mechanism connects a first flow path that flows the liquid in the pressure chamber toward the printhead to the liquid outlet, connects one side of a second flow path to the bottom of the pressure chamber, and connects the other side of the second flow path to the first flow path, with the flow path resistance of the second flow path set greater than the flow path resistance of the first flow path, and the pressure chamber forms a damper mechanism that absorbs pressure fluctuations applied to the ink in the inkjet printhead. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 2018-149685 Summary of the Invention [Problem to be solved by the invention]

[0005] The pressure chamber of the negative pressure regulating valve described above has a large volume because it has a diaphragm (displacement wall) that is in contact with the atmosphere and determines the threshold pressure for opening and closing the valve. As a result, when the valve is opened, the flow rate of the liquid that flows in from the inlet pressure chamber slows down, and stagnant areas occur.

[0006] In the configuration of Patent Document 1, the flow path leading to the recording head side of the pressure chamber is arranged only on the upper vertical side, which causes a problem in that solidified matter and foreign matter tend to remain below the pressure chamber.

[0007] In view of the above problems, an object of the present invention is to provide a negative pressure adjustment valve that can suppress the accumulation of air bubbles and liquid with a high specific gravity in a pressure chamber with a simple configuration, and an inkjet recording apparatus equipped with the same. [Means for solving the problem]

[0008] To achieve the above object, a first aspect of the present invention is a negative pressure adjustment valve connected to a liquid flow path that communicates between a liquid storage portion that stores liquid and a liquid ejection portion that ejects liquid. The negative pressure adjustment valve includes a pressure chamber, a valve member, a diaphragm portion, a pressure plate, and a biasing member. The pressure chamber includes a liquid inlet that communicates with a liquid inlet path, which is a liquid flow path on the liquid storage portion side, and a liquid outlet that is formed above the liquid inlet and communicates with a liquid outlet path, which is a liquid flow path on the liquid ejection portion side. The valve member is disposed at the liquid inlet and is movable between a closed position that closes the liquid inlet and an open position that opens the liquid inlet in response to pressure changes within the pressure chamber. The diaphragm portion constitutes a part of the pressure chamber and displaces inward and outward of the pressure chamber in response to pressure changes within the pressure chamber. The pressure plate is disposed opposite the inner surface of the diaphragm portion and displaces inward and outward of the pressure chamber together with the diaphragm portion to change the volume of the pressure chamber. The biasing member biases the pressure plate in a direction displacing it outward from the pressure chamber. The valve member moves together with the pressure plate between a closed position and an open position due to the displacement of the diaphragm portion inward into the pressure chamber and the displacement of the pressure plate outward from the pressure chamber caused by the biasing force of the biasing member. When the pressure plate displaces inward and outward from the pressure chamber, the change in volume of the pressure chamber increases as it moves from the top to the bottom of the pressure chamber relative to the direction of gravity. [Effects of the Invention]

[0009] According to the first configuration of the present invention, by increasing the rate of change in the volume of the pressure chamber as it moves downward, the flow rate of the liquid flowing from the bottom to the top of the pressure chamber toward the liquid outlet located above the liquid inlet increases. As a result, the efficiency with which solids and liquids with a high specific gravity flow out of the liquid outlet improves, and retention of bubbles and stagnation of the liquid within the pressure chamber can be effectively suppressed. [Brief explanation of the drawings]

[0010] [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, a negative pressure adjustment valve 31 connected to the ink flow path 40, and a recording head 17. [Figure 4] FIG. 1 is a perspective view of the appearance of a negative pressure adjustment valve 31 according to an embodiment of the present invention. [Figure 5] 1 is a side cross-sectional view including an ink inlet 50a and an ink outlet 50b of the negative pressure adjustment valve 31 of this embodiment. [Figure 6] FIG. 10 is a side cross-sectional view including an ink inlet 50a and an ink outlet 50b of the negative pressure adjustment valve 31, showing how liquid is discharged from the negative pressure adjustment valve 31. DETAILED DESCRIPTION OF THE INVENTION

[0011] 1. Configuration of Inkjet Recording Apparatus Hereinafter, an embodiment of the present invention will be described with reference to the drawings. Figure 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.

[0012] 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.

[0013] 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.

[0014] 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.

[0015] 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).

[0016] 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.

[0017] 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.

[0018] 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.

[0019] 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.

[0020] 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.

[0021] 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.

[0022] 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.

[0023] 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 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 of the recording heads 17a to 17c in order to expel thickened ink, foreign matter, and air bubbles from the ink discharge ports. 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 upward to be attached to the undersides of the recording heads 17a to 17c.

[0024] 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, a negative pressure adjustment valve 31 connected to the ink flow path 40, and a recording head 17. In the following description, the recording heads 17a to 17c will be simply referred to as recording head 17. The up and down directions in FIGS. 3 and 4 correspond to the vertical direction (the direction of gravity).

[0025] The ink flow path 40 has an ink inlet path 41 and an ink outlet path 42. A negative pressure adjustment valve 31 is connected between the ink inlet path 41 and the ink outlet path 42.

[0026] Ink introduced into the ink flow path 40 from the ink container 30 (see FIG. 1) is supplied to the recording head 17 via the ink inflow path 41, the negative pressure adjustment valve 31, and the ink outflow path 42. A pressure pump 33 is connected to the ink inflow path 41. The pressure pump 33 maintains the internal pressure of the inflow side 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 side pressure chamber 50 (see FIG. 4).

[0027] It is also possible to adopt a configuration in which the pressure inside the inlet pressure chamber 50 is maintained at a constant pressure by using the ink head pressure, by locating the ink container 30 at a position higher than the negative pressure adjustment valve 31, without providing the pressure pump 33. Furthermore, if a sub-tank (not shown) is located between the ink container 30 and the negative pressure adjustment valve 31, the sub-tank may be located at a position higher than the negative pressure adjustment valve 31.

[0028] 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. 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 ink ejection ports (nozzles) 18 of the recording head 17 due to temperature changes in the space between the ink ejection surface 171 and the cap 201. Attaching the cap 201 keeps the ink ejection surface 171 of the recording head 17 in a sealed state. A suction pump 45 and a waste ink discharge flow path 47 are connected to the cap 201.

[0029] 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.

[0030] 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.

[0031] In this embodiment, the ink outflow path 42 is connected to the recording head 17. In this configuration, the fluid in the ink outflow path 42 is sucked through the recording head 17 by the suction pump 45 and flows out to the waste ink discharge path 47. Therefore, in the ink ejection ports (nozzles) 18 of the recording head 17, liquid always flows from inside the nozzles to outside the nozzles. Therefore, even if the absolute value of the negative pressure by the suction pump 45 is increased, there is no risk of the meniscus in the ink ejection port 18 being drawn in and air bubbles entering the ink ejection port 18.

[0032] [3. Configuration of the negative pressure adjustment valve] Fig. 4 is an external perspective view of a negative pressure adjustment valve 31 according to one embodiment of the present invention. Fig. 5 is a side cross-sectional view including an ink inlet 50a and an ink outlet 50b of the negative pressure adjustment valve 31 of this embodiment. The negative pressure adjustment valve 31 stores ink flowing through the ink flow path 40 and also functions as a pressure adjustment valve that opens and closes the ink flow path 40 in response to the pressure on the recording head 17 side. The negative pressure adjustment valve 31 has a pressure chamber 50, a valve member 51, and an opening / closing pressure adjustment spring 52.

[0033] The pressure chamber 50 has a main body portion 53, a diaphragm portion 55, and a pressure-receiving plate 56. The main body portion 53 is cylindrical with one side (the left side in FIG. 5) open, and has an ink inlet 50a and an ink outlet 50b. The ink inlet 50a is connected to the ink inlet channel 41. The ink outlet 50b is connected to the ink outlet channel 42. The ink outlet 50b is formed at a higher position than the ink inlet 50a.

[0034] In this embodiment, the ink inlet 50a is formed at the lower end of the pressure chamber 50, and the ink outlet 50b is formed at the upper end of the pressure chamber 50. The pressure chamber 50 has a predetermined volume for storing ink that flows in from the ink inlet 50a. The main body 53 has a recess 53a, which is recessed from the inside to the outside of the pressure chamber 50, formed on the surface facing the diaphragm 55 (the right side in FIG. 5).

[0035] The diaphragm portion 55 is formed from a flexible resin film with a laminated structure. The diaphragm portion 55 is fixed with a predetermined amount of slack to an opening in the side surface (the left side surface in FIG. 5) of the main body portion 53, and forms the outer surface of the pressure chamber 50. The diaphragm portion 55 displaces in response to changes in pressure within the pressure chamber 50, thereby changing the volume of the pressure chamber 50.

[0036] The pressure plate 56 is supported by the main body 53 at a swing fulcrum 56a provided at the upper end so as to be able to swing. The pressure plate 56 abuts against the inner surface of the diaphragm 55 (the resin layer facing the inside of the pressure chamber 50), and swings in response to the displacement of the diaphragm 55.

[0037] The pressure-receiving plate 56 has a first protrusion 56b and a second protrusion 56c that are convex from the outside to the inside of the pressure chamber 50. The first protrusion 56a is formed in approximately the center of the pressure chamber 50 in the up-down direction. The first protrusion 56a is formed in a position facing a recess 53a formed in the main body portion 53.

[0038] The opening / closing pressure adjusting spring 52 is disposed between the first convex portion 56a and the concave portion 53a. The biasing force of the opening / closing pressure adjusting spring 52 acts on the pressure receiving plate 56 in a direction that displaces (expands) the diaphragm portion 55 outward.

[0039] The second convex portion 56b is formed below the first convex portion 56a and above the ink inlet 50a. Due to the second convex portion 56b formed on the pressure-receiving plate 56, the volume of the pressure chamber 50 on the side closer to the ink inlet 50a (lower in the direction of gravity) is smaller than the volume on the side closer to the ink outlet 50b (upper in the direction of gravity) before the diaphragm portion 55 is displaced inward of the pressure chamber 50.

[0040] A valve member 51 capable of closing the ink inlet 50a is disposed in the ink inlet 50a. One end of the valve member 51 inserted into the ink inlet 50a is connected to a pressure-receiving plate 56. The valve member 51 is movable between a closed position where it closes the ink inlet 50a and an open position where it opens the ink inlet 50a against the biasing force of an opening / closing pressure adjustment spring 52, in response to displacement of the pressure-receiving plate 56 accompanying pressure changes in the pressure chamber 50.

[0041] 6 is a side cross-sectional view including the ink inlet 50a and the ink outlet 50b of the negative pressure adjustment valve 31, and shows how liquid (initial filling liquid or ink) is discharged from the negative pressure adjustment valve 31. The arrows in FIG. 6 indicate the flow of liquid within the negative pressure adjustment valve 31.

[0042] As ink is consumed in the recording head 17 and the pressure in the pressure chamber 50 decreases, the diaphragm portion 55 is displaced (contracted) inward. As the diaphragm portion 55 is displaced, the pressure-receiving plate 56 swings inward against the biasing force of the opening / closing pressure adjustment spring 52. As a result, the lower end of the pressure-receiving plate 56 presses the valve member 51 toward the ink inlet 50a (open position), opening the ink inlet 50a. As a result, ink is supplied from the ink inlet channel 41 to the pressure chamber 50. When the pressure in the pressure chamber 50 reaches a predetermined negative pressure, the valve member 51 is pushed back into the pressure chamber 50 (closed position), closing the ink inlet 50a and stopping the supply of ink from the ink inlet channel 41 to the pressure chamber 50. In this manner, the ink supply pressure to the recording head 17 is adjusted.

[0043] When performing the suction purge process, the ink ejection surface 171 of the recording head 17 is covered with the cap 201 (see Figure 3 for both), and with the flow path connecting the inside of the cap 201 to the atmosphere closed, the suction pump 45 sucks the space (sealed space) between the ink ejection surface 171 and the cap 201 to generate negative pressure.

[0044] As a result, the pressure chamber 50 of the negative pressure adjustment valve 31 becomes negative pressure, and the diaphragm portion 55 is displaced (contracted) inward. As the diaphragm portion 55 is displaced, the pressure receiving plate 56 swings inward against the biasing force of the opening / closing pressure adjustment spring 52. As a result, the valve member 51 moves toward the ink outlet 50a, opening the ink inlet 50a and connecting the pressure chamber 50 to the ink inflow channel 41. This causes liquid to flow from the ink container 30 through the ink inflow channel 41, the negative pressure adjustment valve 31, and the ink outflow channel 42 to the recording head 17, discharging the liquid from the recording head 17 through the ink ejection ports 18.

[0045] At this time, air bubbles contained in the liquid flowing into the pressure chamber 50 accumulate in the upper part of the pressure chamber 50. Therefore, the air bubbles efficiently flow out from the ink outlet 50b formed in the upper part of the pressure chamber 50 through the ink outlet path 42 to the recording head 17.

[0046] Furthermore, as a result of the pressure change within the pressure chamber 50 causing the lower part of the pressure-receiving plate 56 to swing (displace) toward the inside of the pressure chamber 50, the first convex portion 56a approaches the concave portion 53a of the main body portion 53, and the second convex portion 56b approaches the inner surface of the main body portion 53. As a result, the lower ink flow path within the pressure chamber 50 becomes narrower than the upper ink flow path.

[0047] In other words, the volume of the pressure chamber 50 at the bottom relative to the direction of gravity (vertical direction) is significantly reduced compared to the volume at the top. That is, when the pressure-receiving plate 56 is displaced inward and outward from the pressure chamber 50, the amount of change in the volume of the pressure chamber 50 increases as the pressure chamber 50 moves from the top to the bottom. As a result, the flow rate of the liquid flowing from the ink inlet 50a to the ink outlet 50b inside the pressure chamber 50 from the bottom to the top increases.

[0048] Solid matter such as solidified ink components and foreign matter contained in the liquid that flows into the pressure chamber 50 from the ink inlet 50a due to the suction purge process accumulates in the lower part of the pressure chamber 50. Therefore, by increasing the flow rate of the liquid inside the pressure chamber 50, the solid matter flows out efficiently from the ink outlet 50b formed in the upper part of the pressure chamber 50 through the ink outlet path 42 to the recording head 17.

[0049] With the configuration of this embodiment, when the printer 100 is shipped and a suction purge process is performed to fill the ink flow path 40 with ink or initial filling liquid from an empty state, air bubbles contained in the ink or initial filling liquid are efficiently discharged from the ink outlet 50b formed at the upper end of the pressure chamber 50.

[0050] Furthermore, even when a suction purge process is performed during installation of the printer 100 to replace the initial fill liquid in the ink flow paths 40 with ink, the initial fill liquid, which has a lower density than ink, flows out efficiently from the ink outlet 50b, and therefore no initial fill liquid remains in the pressure chambers 50. This makes it possible to reduce the flow rate of ink flowing to replace the initial fill liquid in the ink flow paths 40 with ink.

[0051] Furthermore, when a suction purge process is performed to expel solidified ink components or foreign matter that has accumulated in the ink flow path 40 while the printer 100 is in use, the pressure-receiving plate 56 is displaced to narrow the lower ink flow path within the pressure chamber 50 compared to the upper ink flow path, thereby increasing the flow rate of the liquid. This allows solidified ink components and foreign matter to flow out smoothly and efficiently from the ink outlet 50b without accumulating below the pressure chamber 50.

[0052] That is, the efficiency with which solids and liquids with a high specific gravity flow out of the ink outlet 50b is improved, and the amount of ink used in the suction purge process can be reduced. Therefore, the negative pressure adjustment valve 31 can effectively suppress the accumulation of air bubbles and stagnation of liquid in the pressure chamber 50. Furthermore, because solids do not remain in the pressure chamber 50, it is possible to avoid the problem of solids getting caught in the gap between the valve member 51 and the ink inlet 50a, preventing the valve member 51 from moving.

[0053] Furthermore, by forming the recess 53a in the main body 53 and the first protrusion 56b in the pressure-receiving plate 56, it is possible to minimize the volume below the pressure chamber 50 while ensuring space for arranging the opening / closing pressure adjustment spring 52. Furthermore, by forming the second protrusion 56c in the pressure-receiving plate 56, the volume below the pressure chamber 50 becomes even smaller when the pressure-receiving plate 56 is displaced inward of the pressure chamber 50. Therefore, the flow rate of the liquid within the pressure chamber 50 can be made even faster.

[0054] Furthermore, by forming the ink inlet 50a at the lower end of the pressure chamber 50, there is no risk of thickened ink with a high specific gravity or foreign matter remaining in the lower part of the pressure chamber 50. Furthermore, by forming the ink outlet 50b at the upper end of the pressure chamber 50, there is no risk of air bubbles or initial filling liquid with a low specific gravity remaining in the upper part of the pressure chamber 50. Therefore, the negative pressure adjustment valve 31 can more effectively suppress the retention of air bubbles and stagnation of liquid in the pressure chamber 50.

[0055] Additionally, 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 swing fulcrum 56a of the pressure-receiving plate 56 is provided below the ink outlet 50b at a predetermined distance. However, the position of the swing fulcrum 56a is not limited to the position in the above-described embodiment, and the swing fulcrum 56a may be provided close to and below the ink outlet 50b. In other words, it is sufficient that when the pressure-receiving plate 56 is displaced inward of the pressure chamber 50, the volume of the pressure chamber 50 decreases from the top to the bottom.

[0056] In the above embodiment, the opening / closing pressure adjusting spring 52 is disposed between the first convex portion 56b formed on the pressure-receiving plate 56 and the concave portion 53a formed on the main body portion 53, but the first convex portion 56b and the concave portion 53a are not essential components, and the opening / closing pressure adjusting spring 52 may be disposed in another position. Also, the second convex portion 56b may be omitted, or two or more second convex portions 56b may be formed.

[0057] In addition, in the above 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 configurations in which other components are connected to the ink flow path 40.

[0058] Furthermore, 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 negative pressure adjustment valve 31 of this embodiment can also be used when a monochrome printer that records monochrome images using black ink is used. [Industrial Applicability]

[0059] The present invention is applicable to 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, and to an inkjet recording device such as an inkjet printer equipped with a negative pressure adjustment valve. [Explanation of symbols]

[0060] 10 Ink container (liquid storage section) 17, 17a to 17c recording head (liquid ejection unit) 18 Ink outlet (nozzle) 31 Negative pressure adjustment valve 33 Pressure pump 40 Ink flow path (liquid flow path) 41 Ink inlet channel (liquid inlet channel) 42 Ink outflow path (liquid outflow path) 45 Suction Pump 47 Waste ink discharge flow path 50 Pressure Chamber 50a Ink inlet (liquid inlet) 50b Ink outlet (liquid outlet) 51 Valve member 52 Opening / closing pressure adjusting spring (biasing member) 53 Main body 55 Diaphragm part 56 Pressure plate 56a Swing fulcrum 56b First convex part 56b Second convex part 100 Printers (inkjet recording devices)

Claims

1. a liquid storage section that stores liquid; a liquid ejection unit that ejects the liquid; A negative pressure regulating valve connected to a liquid flow path communicating between a liquid inlet port communicating with a liquid inlet channel, which is the liquid flow channel on the liquid storage portion side; a liquid outlet formed above the liquid inlet and communicating with a liquid outlet path, which is the liquid flow path on the liquid ejection unit side; a pressure chamber having a valve member disposed at the liquid inlet, the valve member being movable between a closed position at which the liquid inlet is closed and an open position at which the liquid inlet is opened in response to a pressure change in the pressure chamber; a diaphragm portion that constitutes a part of the pressure chamber and displaces inward and outward of the pressure chamber in response to a change in pressure within the pressure chamber; a pressure plate disposed opposite an inner surface of the diaphragm portion and displacing inward and outward together with the diaphragm portion to change the volume of the pressure chamber; a biasing member that biases the pressure receiving plate in a direction that displaces the pressure receiving plate outward from the pressure chamber; and the valve member moves between the closed position and the open position together with the pressure plate by displacement of the diaphragm portion toward the inside of the pressure chamber and displacement of the pressure plate toward the outside of the pressure chamber due to the biasing force of the biasing member, A negative pressure regulating valve characterized in that, when the pressure plate is displaced inward and outward from the pressure chamber, the amount of change in the volume of the pressure chamber increases as it moves from above to below the pressure chamber relative to the direction of gravity.

2. the pressure receiving plate is supported so as to be swingable in a direction toward the inside and outside of the pressure chamber with an upper end portion as a swing fulcrum, 2. The negative pressure regulating valve according to claim 1, wherein when the diaphragm portion is displaced inwardly of the pressure chamber, the lower end of the pressure plate swings inwardly of the pressure chamber, thereby causing the amount of reduction in the volume of the pressure chamber to increase from the top to the bottom of the pressure chamber.

3. The pressure chamber has a main body portion with one side open, The diaphragm portion is fixed to the opening with a predetermined slack, The main body portion is formed with a recessed portion that is recessed from the inside of the pressure chamber toward the outside, The pressure-receiving plate has a first convex portion formed at a position facing the concave portion, the first convex portion having a convex shape extending from the outside toward the inside of the pressure chamber, The negative pressure regulating valve according to claim 1 , wherein the biasing member is disposed between the recess and the first protrusion.

4. 4. The negative pressure regulating valve according to claim 3, wherein the volume of the pressure chamber below the first convex portion is smaller than the volume of the pressure chamber above the first convex portion before the diaphragm portion is displaced inward of the pressure chamber.

5. 5. The negative pressure regulating valve according to claim 4, wherein the pressure plate has one or more second convex portions formed below the first convex portion, the second convex portions having a convex shape extending from the outside to the inside of the pressure chamber.

6. 2. The negative pressure regulating valve according to claim 1, wherein the liquid inlet is formed at a lower end of the pressure chamber, and the liquid outlet is formed at an upper end of the pressure chamber.

7. an ink container for storing liquid ink; one or more recording heads each having a plurality of nozzles for ejecting the ink; a negative pressure adjusting valve according to claim 1 , connected to an ink flow path between the ink container and the recording head; An inkjet recording apparatus comprising:

Images