Liquid dispensing device

Abstract

To provide means capable of gradually adjusting pressure in an internal space of a tank while achieving downsizing of a buffer tank.SOLUTION: A liquid discharge device 100 includes: a tank 34 storing liquid; a head 38 discharging liquid supplied from the tank 34; a first flow channel 61 and a second flow channel 62 connecting the tank 34 and the head 38; a positive pressure pump 63 applying pressure to liquid in a direction toward the head 38 in the first flow channel 61; a negative pressure pump 65 decompressing an internal space of the tank 34; a buffer tank 67 communicated with an internal space 47A of a tank 47; an atmosphere communication passage 68 communicating the buffer tank 67 and the outside; and a valve 69 opening / closing the atmosphere communication passage 68. A capacity of the buffer tank 67 is smaller than that of the tank 34. The atmosphere communication passage 68 has a thin diameter part 68DD having an inner diameter R2 smaller than an inner diameter R1 of an opening end 68CC opened in the outside.SELECTED DRAWING: Figure 4

Description

Technical Field

[0001] The present invention relates to a liquid discharge device that discharges a liquid stored in a tank from a head.

Background Art

[0002] As a liquid discharge device that discharges ink from a head, for example, a device described in Patent Document 1 is known. The device of Patent Document 1 includes a head unit having a storage unit that stores ink and a head that discharges ink, a degassing buffer tank connected to the storage unit via a pipe that opens to the atmosphere, and a pressure control electromagnetic valve that opens and closes the pipe. When the pressure in the degassing buffer tank becomes lower than a predetermined pressure, the device opens the pressure control electromagnetic valve, takes in air into the degassing buffer tank, and adjusts the pressure in the degassing buffer tank to the predetermined pressure.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] )]] In the device described in Patent Document 1, when the capacity of the degassing buffer tank is reduced from the viewpoint of miniaturization, the capacity in which air accumulates when the pressure control electromagnetic valve is opened becomes smaller, so air easily flows into the storage unit through the pipe. As a result, when the pressure control electromagnetic valve is opened, the pressure in the storage unit easily rises suddenly. If the pressure in the storage unit rises suddenly, pressure fluctuations may occur in the head, and there is a risk of problems such as breakage of the nozzle meniscus.

[0005] An object of the present invention is to provide a means capable of gently adjusting the pressure in the internal space of a tank while achieving miniaturization of the buffer tank. [Means for solving the problem]

[0006] (1) The liquid discharge device according to the present invention comprises a tank for storing liquid, a head for discharging liquid supplied from the tank, a first flow path and a second flow path connecting the tank and the head, a positive pressure pump for applying pressure to the liquid in the first flow path toward the head, a negative pressure pump for reducing the internal space of the tank, a buffer tank communicating with the internal space of the tank, an atmospheric communication passage connecting the buffer tank to the outside, and a valve for opening and closing the atmospheric communication passage. The capacity of the buffer tank is smaller than the capacity of the tank. The atmospheric communication passage has a narrow diameter portion whose inner diameter is smaller than the inner diameter of the opening end that opens to the outside.

[0007] When the positive and negative pressure pumps are driven with the valves closed, and liquid is circulating between the tank and the head through the first and second flow paths, if the positive and negative pressure pumps are stopped, the internal space of the tank and buffer tank may be under negative pressure relative to atmospheric pressure. When the valves are opened at that time, air flows into the buffer tank and the tank from the outside through the narrow-diameter section. Even if the capacity of the buffer tank is smaller than the capacity of the tank, the narrow-diameter section prevents a rapid increase in pressure inside the tank. Therefore, the pressure inside the tank can be adjusted gradually while miniaturizing the buffer tank.

[0008] (2) The lower surface of the internal space of the buffer tank may be located above the upper surface of the internal space of the tank.

[0009] When the valve is opened, the liquid that has flowed into the buffer tank flows into the tank due to gravity.

[0010] (3) The small diameter portion may be located at the open end.

[0011] Liquid entering the atmospheric communication passage from the buffer tank is less likely to reach the narrow-diameter section. As a result, clogging of the narrow-diameter section by liquid is suppressed.

[0012] (4) The inner diameter of the narrow portion may be 20% or less of the inner diameter of the open end.

[0013] (5) The inner diameter of the small diameter portion may be 0.3 mm or less.

[0014] (6) The atmospheric communication passage may have a portion extending downward from the buffer tank toward the valve and a portion extending upward from the valve. The open end may be facing downward.

[0015] Liquid entering the atmospheric communication passage from the buffer tank has difficulty reaching the opening. [Effects of the Invention]

[0016] According to the present invention, it is possible to miniaturize the buffer tank while gradually adjusting the pressure inside the tank. [Brief explanation of the drawing]

[0017] [Figure 1] Figure 1 is an external perspective view of an image recording device 100 according to an embodiment of the present invention. [Figure 2] Figure 2 is a cross-sectional view showing the section II-II in Figure 1. [Figure 3] Figure 3 is a perspective view of the area surrounding the second atmospheric communication passage 68, including its open end 68CC. [Figure 4] Figure 4 is a cross-sectional view of the area including the disk member 68D in the second atmospheric communication passage 68. [Modes for carrying out the invention]

[0018] Hereinafter, preferred embodiments of the present invention will be described. It should be noted that this embodiment is merely one embodiment of the present invention, and it is needless to say that the embodiment can be changed without changing the gist of the present invention. In the following description, the progression from the starting point to the ending point of the arrow is expressed as the direction, and the movement back and forth on the line connecting the starting point and the ending point of the arrow is expressed as the orientation. Further, in the following description, the vertical direction 7 is defined based on the state where the image recording apparatus 100 is installed for use (the state in FIG. 1), the front-rear direction 8 is defined with the side where the discharge port 33 is provided as the front side (front surface), and the left-right direction 9 is defined when viewing the image recording apparatus 100 from the front side (front surface).

[0019] [External Configuration of Image Recording Apparatus 100] The image recording apparatus 100 (an example of a liquid ejection apparatus) shown in FIG. 1 records an image on a sheet S forming a roll body 37 (see FIG. 2) by an inkjet recording method.

[0020] As shown in FIG. 1, the image recording apparatus 100 includes a housing 30. The housing 30 includes an upper housing 31 and a lower housing 32. The upper housing 31 and the lower housing 32 are generally rectangular parallelepiped in shape as a whole and are sized to be placed on a desktop. That is, the image recording apparatus 100 is suitable for being placed on a desktop and used. Of course, the image recording apparatus 100 may be placed on a floor surface or a rack and used. Note that a frame for supporting each member may be appropriately provided inside the housing 30.

[0021] As shown in FIG. 2, the upper housing 31 is rotatably supported by the lower housing 32. The upper housing 31 is rotatable about a rotation axis 15 provided at the rear lower end and extending in the left-right direction 9 between a closed position shown in FIG. 2 and an open position. Note that the configuration in which the upper housing 31 rotates is not limited to that by the rotation axis 15, and for example, it may rotate by a hinge or the like.

[0022] As shown in FIG. 2, when the upper housing 31 is in the closed position, the internal space 31A of the upper housing 31 and the internal space 32A of the lower housing 32 are shielded from the outside. When the upper housing 31 is in the open position, the internal space 31A of the upper housing 31 and the internal space 32A of the lower housing 32 are exposed to the outside.

[0023] As shown in FIG. 1, a slit-shaped discharge port 33 that is long in the left-right direction 9 is formed in the front surface 32F of the lower housing 32. The sheet S (see FIG. 2) on which an image has been recorded is discharged from the discharge port 33.

[0024] An operation panel 44 is provided on the front surface 31F of the upper housing 31. The user inputs to the operation panel 44 to operate the image recording apparatus 100 and confirm various settings.

[0025] As shown in FIG. 1, a right cover 35A is located on the right surface 32R of the lower housing 32. By opening and closing the right cover 35A, a holder 35 etc. (see FIG. 2) located in the sheet storage space 32C is exposed or shielded.

[0026] As shown in FIG. 1, a front cover 39 is located on the front surface 32F of the lower housing 32. The front cover 39 can open such that the upper end side falls forward around a rotation axis (not shown) that extends along the left-right direction 9 near the lower end. By opening and closing the front cover 39, a mounting case 110 etc. (see FIG. 2) located in the internal space 32A of the lower housing 32 is exposed or shielded.

[0027] [Internal Configuration of Image Recording Apparatus 100] As shown in FIG. 2, a holder 35, a tensioner 45, a pair of conveyance rollers 36, a pair of conveyance rollers 40, a head unit 38, a platen 51, an ink tank 34, a mounting case 110, and an ink sub-tank (an example of a tank) 47 etc. are arranged in the internal spaces 31A, 32A. Although not shown, a fixing unit, an image sensor, a cutter, a maintenance mechanism etc. may be located in the internal space 32A.

[0028] A partition wall 41 is provided in the internal space 32A. The partition wall 41 separates the rear lower part of the internal space 32A, thereby partitioning the seat storage space 32C. The seat storage space 32C is surrounded by the partition wall 41 and the lower housing 32, and is isolated from the head unit 38 and other components.

[0029] The tensioner 45 is located above the partition wall 41 at the rear of the internal space 32A. The tensioner 45 has an outer peripheral surface 45A facing outwards from the lower housing 32. The outer peripheral surface 45A is larger than the maximum width of the sheet in the left-right direction 9 and has a shape that is symmetrical with respect to the paper feeding center (the center of the sheet S in the left-right direction 9). The upper end of the outer peripheral surface 45A is at approximately the same vertical position as the nip D of the conveying roller pair 36 in the vertical direction 7.

[0030] The sheet S, pulled out from the roll body 37, is placed on and in contact with the outer circumferential surface 45A. The sheet S curves forward along the outer circumferential surface 45A and extends in the conveying direction 8A, and is guided by the conveying roller pair 36. The conveying direction 8A is forward along the front-rear direction 8. The tensioner 45 applies tension to the sheet S by a well-known method.

[0031] A pair of conveyor rollers 36 is located in front of the tensioner 45. The pair of conveyor rollers 36 has a conveyor roller 36A and a pinch roller 36B. The conveyor roller 36A and the pinch roller 36B are in contact with the upper end of the outer circumferential surface 45A at approximately the same vertical position.

[0032] A pair of conveyor rollers 40 is located in front of the conveyor roller pair 36. The conveyor roller pair 40 has a conveyor roller 40A and a pinch roller 40B. The conveyor roller 40A and the pinch roller 40B are in contact with the upper end of the outer circumferential surface 45A at approximately the same vertical position.

[0033] The conveyor rollers 36A and 40A are driven by a motor (not shown) and rotate. The conveyor roller pair 36 rotates while nipping the sheet S extending from the tensioner 45 in the conveying direction 8A, thereby feeding it along the conveying surface 43A in the conveying direction 8A. The conveyor roller pair 40 rotates while nipping the sheet S fed out by the conveyor roller pair 36, thereby feeding it along the conveying direction 8A. In addition, the rotation of the conveyor roller pairs 36 and 40 causes the sheet S to be pulled out from the sheet storage space 32C through the gap 42 towards the tensioner 45.

[0034] As shown in Figure 2, a transport path 43 is formed in the internal space 32A, extending from the upper end of the outer peripheral surface 45A to the discharge port 33. The transport path 43 extends almost linearly along the transport direction 8A and is a space through which the sheet S can pass. In detail, the transport path 43 extends in the transport direction 8A and the left-right direction 9 and follows a transport surface 43A that is longer in the transport direction 8A. In Figure 2, the transport surface 43A is shown by a dashed line indicating the transport path 43. The transport path 43 is partitioned by guide members (not shown) located at a distance in the vertical direction 7, as well as a head unit 38, a platen 51, and the like.

[0035] The head unit 38 is located above the transport path 43, downstream of the transport roller pair 36 in the transport direction 8A. The head unit 38 has a head module 49 having a plurality of nozzles 38A. The plurality of nozzles 38A discharge ink (an example of a liquid) supplied from the ink sub-tank 47 downward toward the sheet S supported by the transport belt 101. This records an image on the sheet S.

[0036] The platen 51 is located below the conveyor path 43, downstream of the conveyor roller pair 36 in the conveying direction 8A. The platen 51 is located below the head unit 38 and faces the head unit 38. The platen 51 has a conveyor belt 101 and a support section 104. The conveyor belt 101 supports the sheet S, which is conveyed in the conveying direction 8A by the conveyor roller pair 36 and located directly below the head unit 38. The conveyor belt 101 conveys the supported sheet S in the conveying direction 8A.

[0037] The mounting case 110 is located near the front and bottom ends of the lower housing 32 and is a box shape that opens forward. The ink tank 34 is inserted into the mounting case 110 facing backward. An ink needle 112 extending forward is located on the rear end surface 111 of the mounting case 110. The front end of the ink needle 112 is open, and the rear end is connected to an ink tube 113. The ink tube 113 connects the internal space of the ink needle 112 and the internal space 47A of the ink sub-tank 47, allowing ink to flow. When the ink tank 34 is mounted in the mounting case 110, the ink needle 112 is inserted into the outlet (not shown) of the ink tank 34. As a result, the ink stored in the ink tank 34 is supplied to the ink sub-tank 47 through the ink needle 112 and the ink tube 113.

[0038] The ink tank 34 stores ink. Ink is a liquid containing pigments and other materials. The ink has a viscosity suitable for uniformly dispersing the pigments. The pigments are what give the ink its color. When the ink in the ink tank 34 is consumed, it is removed from the mounting case 110 and replaced with a new ink tank 34 that contains ink.

[0039] The ink sub-tank 47 is located above the ink tank 34. The ink sub-tank 47 stores the ink supplied from the ink tank 34. A liquid supply passage 61 (an example of a first flow path) and a liquid discharge passage 62 (an example of a second flow path) are connected to the ink sub-tank 47. The liquid supply passage 61 and the liquid discharge passage 62 are, for example, the internal spaces of tubes, and connect the ink sub-tank 47 and the head unit 38 so that ink can flow through them.

[0040] A positive pressure pump 63 is located in the liquid supply passage 61. The positive pressure pump 63 applies pressure to the ink in the liquid supply passage 61 in a direction toward the head unit 38. A diaphragm pump can be used as the positive pressure pump 63. A pressure sensor 48 is located in the liquid supply passage 61. The pressure sensor 48 detects the pressure of the ink in the liquid supply passage 61 and outputs a detection signal to the controller.

[0041] A first atmospheric communication passage 64 is connected to the ink sub-tank 47, which communicates with the atmosphere. One end of the first atmospheric communication passage 64 opens to the upper part of the internal space 47A of the ink sub-tank 47, and the other end opens to the internal space 31A of the upper housing 31. A negative pressure pump 65 is located in the first atmospheric communication passage 64. The negative pressure pump 65 reduces the pressure in the internal space 47A of the ink sub-tank 47 by sucking in air from the internal space 47A of the ink sub-tank 47. For example, a diaphragm pump can be used as the negative pressure pump 65. The air sucked in by the negative pressure pump 65 is released into the atmosphere through the first atmospheric communication passage 64. The driving of the negative pressure pump 65 and the positive pressure pump 63 is controlled by a controller (not shown).

[0042] The ink sub-tank 47 is connected to the buffer tank 67 through a connecting channel 66. One end of the connecting channel 66 opens to the upper surface 47B of the internal space 47A of the ink sub-tank 47. The other end of the connecting channel 66 opens to the lower surface 67B of the internal space 67A of the buffer tank 67.

[0043] The buffer tank 67 is located above the ink sub-tank 47. The lower surface 67B of the internal space 67A of the buffer tank 67 is located above the upper surface 47B of the internal space 47A of the ink sub-tank 47. The capacity of the buffer tank 67 is smaller than the capacity of the ink sub-tank 47. The buffer tank 67 is intended to temporarily hold the outside air that flows into the ink sub-tank 47, thereby preventing a sudden influx of outside air into the internal space 47A of the ink sub-tank 47. The buffer tank 67 is also intended to store the ink that flows in from the ink sub-tank 47 through the connecting channel 66.

[0044] A second atmospheric communication passage 68 (an example of an atmospheric communication passage) is connected to the buffer tank 67. The second atmospheric communication passage 68 extends in a way that it bends vertically toward an open end 68CC that opens to the atmosphere. Specifically, as shown in Figures 3 and 4, the second atmospheric communication passage 68 has a lower part 68A, an upper part 68B, an open end 68C, and a disc member 68D. The lower part 68A extends downward from the buffer tank 67 and is connected to an atmospheric release valve 69 (an example of a valve) described later. The upper part 68B extends upward from the atmospheric release valve 69. The open end 68C extends laterally from the upper part 68B, with the open end 68CC formed facing downward. A cylindrical connecting part 70 is formed at the open end 68CC, having an inner diameter larger than the inner diameter R1 of the open end 68CC.

[0045] The disc member 68D is located at the open end 68CC of the open end 68C. The disc member 68D is formed in the shape of a circular flat plate. The disc member 68D is fitted into the connecting portion 70. The disc member 68D has a narrow diameter portion 68DD, which is a through hole that penetrates the disc member 68D. The narrow diameter portion 68DD is located at the center of the disc member 68D. The center of the inner diameter R2 of the narrow diameter portion 68DD coincides with the center of the inner diameter R1 of the open end 68CC. The inner diameter R2 of the narrow diameter portion 68DD is 20% or less of the inner diameter R1 of the open end 68CC. Specifically, the inner diameter R1 is in the range of 1.5 mm to 2.0 mm, and the inner diameter R2 is 0.3 mm or less. The atmospheric release valve 69 opens and closes the second atmospheric communication passage 68. The atmospheric release valve 69 is, for example, a solenoid valve, and its opening and closing is controlled by a controller (not shown). Furthermore, the atmospheric release valve 69 opens when power is lost.

[0046] [Ink supply from ink tank 34 to ink sub-tank 47] The controller drives the negative pressure pump 65, for example, based on the fact that the ink tank 34 is installed in the mounting case 110. When the negative pressure pump 65 is driven, the gas layer in the ink sub-tank 47 is depressurized, and ink is drawn from the ink tank 34 to the ink sub-tank 47. By driving the negative pressure pump 65 for a certain period of time, for example, a predetermined amount of ink is supplied from the ink tank 34 to the ink sub-tank 47.

[0047] [Image recording operation] Next, the operation of the image recording device 100 when an image is recorded on the sheet S pulled out from the roll 37 will be described.

[0048] When the controller receives a command from the operation panel 44 or an external device such as an information processing device connected to the image recording device 100 via LAN to record an image on the sheet S, it drives the positive pressure pump 63 and the negative pressure pump 65. It also closes the atmospheric release valve 69. As a result, the pressure difference between the ink sub-tank 47 and the head unit 38 causes the ink to circulate through the liquid supply passage 61 and the liquid discharge passage 62. At this time, ink is ejected from the nozzle 38A of the head unit 38 toward the sheet S supported by the platen 51, and an image is recorded on the sheet S. The sheet S with the recorded image is cut to a predetermined size by a cutter or the like and discharged from the discharge port 33. As ink is ejected from the head unit 38, ink is supplied from the ink tank 34 to the ink sub-tank 47.

[0049] The ink pressure in the liquid supply passage 61 may fluctuate due to ink consumption during printing. Based on the detection signal from the pressure sensor 48, when the controller determines that the pressure in the liquid supply passage 61 has exceeded a predetermined threshold, the controller opens the atmospheric release valve 69. This allows outside air to flow into the internal space 47A of the ink sub-tank 47 through the second atmospheric communication passage 68. At this time, the outside air flows into the ink sub-tank 47 through the narrow diameter section 68DD, but the narrow diameter section 68DD creates a greater flow resistance than the open end 68CC, so even if the capacity of the buffer tank 67 is smaller than the capacity of the ink sub-tank 47, outside air will not flow into the ink sub-tank 47 all at once. Therefore, a rapid increase in the pressure in the internal space 47A of the ink sub-tank 47 is suppressed.

[0050] Suppose the power to the image recording device 100 is turned off during printing. When the power is turned off, the positive pressure pump 63 and negative pressure pump 65, which are in operation, stop. Also, when the power is turned off, the atmospheric release valve 69 opens. If the internal space 47A of the ink sub-tank 47 and the internal space 67A of the buffer tank 67 are under negative pressure, this negative pressure causes ink to flow from the head unit 38 to the ink sub-tank 47 through the liquid discharge passage 62. Due to the inflow of ink, there is a risk that ink exceeding the capacity of the ink sub-tank 47 may flow into the buffer tank 67 through the connecting passage 66. However, when the power is turned off, the atmospheric release valve 69 opens, and if the internal space 47A of the ink sub-tank 47 and the internal space 67A of the buffer tank 67 are under negative pressure, outside air flows in through the second atmospheric communication passage 68. This prevents ink from the ink sub-tank 47 from flowing into the buffer tank 67 through the connecting passage 66. Even if ink temporarily flows into the buffer tank 67, since the atmospheric release valve 69 is open, the ink that has flowed into the internal space 67A of the buffer tank 67 will flow back to the ink sub-tank 47 through the connecting channel 66 due to gravity.

[0051] [Effects of the Embodiment] In the image recording device 100, even when the atmospheric release valve 69 is opened to adjust the negative pressure in the internal space 47A of the ink sub-tank 47, outside air is drawn into the ink sub-tank 47 through the narrow-diameter section 68DD. The narrow-diameter section 68DD suppresses the rapid inflow of outside air into the ink sub-tank 47, so the capacity of the buffer tank 67 can be made smaller than the capacity of the ink sub-tank 47. As a result, the buffer tank 67 can be miniaturized while the pressure fluctuations in the internal space 47A of the ink sub-tank 47 can be adjusted gradually.

[0052] In the image recording device 100, if ink flows into the buffer tank 67, the volume of air that maintains the negative pressure in the buffer tank 67 decreases, leading to a deterioration in print quality. In the image recording device 100, the lower surface 67B of the internal space 67A of the buffer tank 67 is located above the upper surface 47B of the internal space 47A of the ink sub-tank 47. Therefore, when the atmospheric release valve 69 is opened, the liquid that flows into the buffer tank 67 flows back to the ink sub-tank 47 through the connecting channel 66 due to gravity. As a result, the negative pressure maintenance capacity of the buffer tank 67 is restored, and the deterioration of print quality can be suppressed. In addition, ink is not wasted compared to when the ink that flows into the buffer tank 67 is discharged by a pump or the like.

[0053] In the image recording device 100, the narrow-diameter portion 68DD of the second atmospheric communication passage 68 is located at the open end 68CC that opens to the atmosphere. Therefore, even if ink enters the second atmospheric communication passage 68 from the buffer tank 67, the ink is unlikely to reach the narrow-diameter portion 68DD. As a result, clogging of the narrow-diameter portion 68DD by ink is suppressed.

[0054] In the image recording device 100, the inner diameter R2 of the narrow-diameter section 68DD is 20% or less of the inner diameter R1 of the open end 68CC, so that outside air does not flow in all at once into the ink sub-tank 47 through the second atmospheric communication passage 68.

[0055] In the image recording device 100, the inner diameter R2 of the narrow-diameter section 68DD is 0.3 mm or less, so that outside air does not flow rapidly into the ink sub-tank 47 through the second atmospheric communication passage 68.

[0056] In the image recording device 100, the second atmospheric communication passage 68 has a lower portion 68A that extends downward from the buffer tank 67 toward the atmospheric release valve 69, an upper portion 68B that extends upward from the atmospheric release valve 69, and an open end portion 68C that extends laterally from the upper portion 68B and has an open end portion 68CC formed facing downward. Therefore, even if ink enters the second atmospheric communication passage 68 from the buffer tank 67, it is difficult for the ink to reach the open end portion 68CC.

[0057] [Differentiation] In the image recording device 100, the small diameter portion 68DD was located at the opening end 68CC of the opening end 68C of the second atmospheric communication passage 68, but it is not particularly limited as long as it is located in the second atmospheric communication passage 68. For example, the small diameter portion 68DD may be located on the atmospheric release valve 69 side of the opening end 68CC of the opening end 68C. Also, the small diameter portion 68DD may be located in the lower portion 68A that extends downward from the buffer tank 67 and is connected to the atmospheric release valve 69, or it may be located in the upper portion 68B that extends upward from the atmospheric release valve 69.

[0058] In the image recording device 100, the controller opens the atmospheric release valve 69 when it determines, based on the detection signal from the pressure sensor 48 that detects the pressure of the ink in the liquid supply passage 61, that the pressure in the liquid supply passage 61 has become greater than a predetermined threshold. Alternatively, a pressure sensor for detecting the pressure inside the ink sub-tank 47 may be provided, and the atmospheric release valve 69 may be opened when it determines, based on the detection signal from this pressure sensor, that the negative pressure inside the ink sub-tank 47 has become greater than a predetermined threshold. [Explanation of symbols]

[0059] 38. Head Unit 47. Ink Subtank 47A...Internal space 47B...Top surface 61...Liquid supply path 62...Liquid drain path 63... Positive pressure pump 65. Vacuum pump 67. Buffer Tank 67A...Internal space 67B...Bottom surface 68...Second Atmospheric Linkage 68A...Lower part 68B...Upper part 68CC...Open end 68DD...Small diameter part 69. Atmospheric vent valve 100...Image recording device R1... Inner diameter R2... Inner diameter

Claims

1. A tank for storing liquid, A head that discharges the liquid supplied from the above tank, A first flow path and a second flow path connecting the above-mentioned tank and the above-mentioned head, A positive pressure pump that applies pressure to the liquid in the first flow path toward the head, A negative pressure pump for reducing the internal space of the above tank, A buffer tank connected to the internal space of the above tank, An atmospheric communication passage connecting the above buffer tank to the outside, A valve for opening and closing the above-mentioned atmospheric communication passage, It is equipped with, The capacity of the buffer tank mentioned above is smaller than the capacity of the tank mentioned above. The above-mentioned atmospheric communication passage is a liquid discharge device having a narrow-diameter section whose inner diameter is smaller than the inner diameter of the open end that opens to the outside.

2. The liquid discharge device according to claim 1, wherein the lower surface of the internal space of the buffer tank is located above the upper surface of the internal space of the tank.

3. The liquid dispensing device according to claim 1 or 2, wherein the above-mentioned narrow diameter portion is located at the above-mentioned open end.

4. The liquid dispensing device according to claim 3, wherein the inner diameter of the small diameter portion is 20% or less of the inner diameter of the open end.

5. The liquid dispensing device according to claim 4, wherein the inner diameter of the above-mentioned small diameter portion is 0.3 mm or less.

6. The above-mentioned atmospheric communication passage has a portion that extends downward from the buffer tank toward the valve and a portion that extends upward from the valve. The liquid dispensing device according to any one of claims 1 to 5, wherein the above-mentioned open end faces downward.

Images