Liquid dispensing device

Abstract

To provide a liquid discharge device which can sufficiently secure a passage length between a liquid supply passage and a pressure sensor in a narrow space between a filter and a head.SOLUTION: A liquid discharge device includes: a tank 47 in which liquid is stored; a head 38 which discharges the liquid supplied from the tank 47; a liquid supply passage 61 connecting the tank 47 with the head 38; a filter 66 disposed at an upstream of the head 38 in the liquid supply passage 61; a branch passage 67 coupled to an area between the head 38 and the filter 66 in the liquid supply passage 61; and a pressure sensor 48 disposed at the branch passage 67. The pressure sensor 48 is located at a position higher than the filter 66. In the liquid supply passage 61, a first position 67A to which the branch passage 67 is coupled is located at a position lower than a second position 611AA connected to an outflow port 66B of the filter 66.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present invention relates to a liquid ejection device that ejects liquid stored in a tank from a head. [Background technology]

[0002] A known example of a liquid ejection device that ejects ink from a head is the inkjet recording device described in Patent Document 1. The recording device of Patent Document 1 includes a recording head, an ink tank, a supply path connecting the recording head and the ink tank, a filter provided in the supply path, and a pressure measuring unit that detects the pressure in the supply path just before the recording head. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2012-232447 Summary of the Invention [Problem to be solved by the invention]

[0004] It is conceivable that a pressure sensor is used for the pressure measurement unit. The pressure sensor electrically detects the deformation of a diaphragm, which deforms in response to pressure fluctuations, and outputs a detection signal. In the recording device described in Patent Document 1, the pressure sensor is disposed between the filter and the recording head, and the supply channel and the pressure sensor are connected by a flow path such as a tube. When the pressure sensor is used without coming into contact with ink, the branch flow path branching from the supply channel to the sensor is filled with air.

[0005] However, if the distance from the supply channel to the pressure sensor in the branch flow channel is short, there is a risk that ink flowing through the supply channel will enter the pressure sensor and come into contact with the diaphragm. When ink comes into contact with the diaphragm, the detection signal from the pressure sensor is likely to become unstable. The filter installed in the supply channel removes foreign matter from the ink flowing to the print head, so it is desirable to position it close to the print head. On the other hand, while it is desirable to position the pressure sensor downstream of the filter, if the filter is positioned close to the print head, there is insufficient space to position the pressure sensor, and the distance between the supply channel and the diaphragm is likely to become short.

[0006] The present invention has been made in consideration of the above-mentioned circumstances, and its purpose is to provide a liquid ejection device that can ensure sufficient flow path length between the liquid supply path and the pressure sensor in the narrow space between the filter and the head. [Means for solving the problem]

[0007] (1) A liquid ejection device according to the present invention includes a tank for storing liquid, a head for ejecting liquid supplied from the tank, a liquid supply path connecting the tank and the head, a filter disposed in the liquid supply path upstream of the head, a branch path connected in the liquid supply path between the head and the filter, and a pressure sensor disposed in the branch path. The pressure sensor is located above the filter. In the liquid supply path, a first position to which the branch path is connected is located below a second position connected to the outlet port of the filter.

[0008] Because the first position is located lower than the second position, the length of the branch flow path from the first position to the pressure sensor can be increased. This ensures a sufficient length of flow path between the liquid supply path and the pressure sensor in the narrow space between the filter and the head, preventing liquid from infiltrating the pressure sensor. As a result, the detection signal from the pressure sensor is stabilized, allowing the pressure in the liquid supply path to be detected accurately.

[0009] (2) The branch flow path may extend linearly upward from the first position to the pressure sensor.

[0010] The space occupied by the branch flow paths can be reduced.

[0011] (3) The liquid supply path may have a first portion extending upward from the outlet port of the filter, a second portion extending from the first portion in a horizontal direction intersecting the vertical direction, a third portion extending downward from the second portion, and a fourth portion extending from the third portion in the horizontal direction to the first position.

[0012] The length of the flow path from the first position to the pressure sensor can be increased by the amount of the vertical separation between the second portion and the fourth portion, so that the liquid can be prevented from entering the pressure sensor.

[0013] (4) The direction in which the liquid flows through the second portion may be opposite to the direction in which the liquid flows through the fourth portion.

[0014] The space required for arranging the liquid supply path can be reduced.

[0015] (5) The liquid supply path may have a tube that forms a straight portion and a pipe joint that forms a bent portion.

[0016] Even if the tube is made of a material that is difficult to bend, the liquid supply path can be easily routed.

[0017] (6) The liquid supply path may further include a liquid discharge path connecting the tank and the head, a positive pressure pump disposed in the liquid supply path, and a negative pressure pump that reduces the pressure in the internal space of the tank.

[0018] (7) The liquid supply channel may have a fifth portion that extends upward and then turns back downward, upstream of a third position where the liquid supply channel is connected to the inlet port of the filter.

[0019] The space required for arranging the filter can be reduced.

[0020] (8) The diameter of the branch channel may be larger than the diameter of the liquid supply channel.

[0021] This makes it difficult for the liquid to enter the branch flow path from the liquid supply path. [Effects of the Invention]

[0022] According to the present invention, a sufficient flow path length between the liquid supply path and the pressure sensor can be ensured in the narrow space between the filter and the head. [Brief explanation of the drawings]

[0023] [Figure 1] FIG. 1 is a perspective view showing the appearance of an image recording device 100 according to an embodiment of the present invention. [Figure 2] FIG. 2 is a cross-sectional view showing the II-II cross section of FIG. [Figure 3] FIG. 3 is a perspective view of the liquid supply channel 61 and its surroundings including the filter 66. FIG. DETAILED DESCRIPTION OF THE INVENTION

[0024] A preferred embodiment of the present invention will be described below. Note that this embodiment is merely one embodiment of the present invention, and it goes without saying that the embodiment can be modified without departing from the gist of the present invention. In the following description, the direction from the start point of an arrow to the end point is expressed as a direction, and the movement on the line connecting the start point and end point of an arrow is expressed as a direction. In the following description, the up-down direction 7 is defined based on the state in which the image recording device 100 is installed and ready 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 near side (front), and the left-right direction 9 is defined when viewing the image recording device 100 from the near side (front).

[0025] [External Configuration of Image Recording Device 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.

[0026] As shown in FIG. 1, the image recording device 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 overall, and are large enough to be placed on a table. That is, the image recording device 100 is suitable for use while being placed on a table. Of course, the image recording device 100 may also be used while being placed on the floor or a rack. Note that a frame for supporting each component may be provided inside the housing 30 as appropriate.

[0027] As shown in Fig. 2, upper housing 31 is rotatably supported by lower housing 32. Upper housing 31 is rotatable between a closed position and an open position shown in Fig. 2 about a rotation shaft 15 that is provided at the lower rear end and extends in the left-right direction 9. Note that the configuration for rotating upper housing 31 is not limited to rotation by rotation shaft 15, and it may also be rotated by, for example, a hinge.

[0028] 2, when upper housing 31 is in the closed position, internal space 31A of upper housing 31 and internal space 32A of lower housing 32 are shielded from the outside. When upper housing 31 is in the open position, internal space 31A of upper housing 31 and internal space 32A of lower housing 32 are exposed to the outside.

[0029] 1, a slit-shaped discharge opening 33 that is long in the left-right direction 9 is formed on a front surface 32F of the lower housing 32. From the discharge opening 33, a sheet S (see FIG. 2) on which an image has been recorded is discharged.

[0030] An operation panel 44 is provided on the front surface 31F of the upper housing 31. A user inputs to the operation panel 44 to operate the image recording device 100 and to confirm various settings.

[0031] 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, the holder 35 and other components (see FIG. 2) located in the sheet accommodating space 32C are exposed or covered.

[0032] 1, a front cover 39 is located on the front surface 32F of the lower housing 32. The front cover 39 can be opened by tilting its upper end forward around a pivot shaft (not shown) that extends in the left-right direction 9 near the bottom end. By opening and closing the front cover 39, the attachment case 110 and the like (see FIG. 2) located in the internal space 32A of the lower housing 32 are exposed or covered.

[0033] [Internal configuration of image recording device 100] 2, the internal spaces 31A and 32A are provided with a holder 35, a tensioner 45, a pair of transport rollers 36, a pair of transport rollers 40, a head unit 38 (an example of a head), a platen 51, an ink tank 34, an attachment case 110, and an ink sub-tank 47 (an example of a tank). Although not shown, the internal space 32A may also be provided with a fixing unit, an image sensor, a cutter, a maintenance mechanism, etc.

[0034] A partition wall 41 is provided in the internal space 32A. The partition wall 41 divides the rear lower part of the internal space 32A to define a seat accommodating space 32C. The seat accommodating space 32C is surrounded by the partition wall 41 and the lower housing 32, and is a space isolated from the head unit 38 and the like.

[0035] The tensioner 45 is located at the rear of the internal space 32A and above the partition wall 41. The tensioner 45 has an outer peripheral surface 45A facing outward from the lower housing 32. The outer peripheral surfaces 45A are equal to or larger than the maximum width of the sheet in the left-right direction 9 and have shapes that are symmetrical with respect to the center of the sheet passage (the center of the sheet S in the left-right direction 9). The upper end of the outer peripheral surface 45A is located at approximately the same vertical position as the nip D of the conveying roller pair 36 in the up-down direction 7.

[0036] The sheet S pulled out from the roll body 37 is hung on and contacts the outer peripheral surface 45A. The sheet S curves forward along the outer peripheral surface 45A, 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.

[0037] The pair of conveying rollers 36 is located in front of the tensioner 45. The pair of conveying rollers 36 includes a conveying roller 36A and a pinch roller 36B. The conveying roller 36A and the pinch roller 36B abut on the outer peripheral surface 45A at approximately the same vertical position as the upper end of the outer peripheral surface 45A.

[0038] A conveying roller pair 40 is located in front of the conveying roller pair 36. The conveying roller pair 40 has a conveying roller 40A and a pinch roller 40B. The conveying roller 40A and the pinch roller 40B abut at approximately the same vertical position as the upper end of the outer circumferential surface 45A.

[0039] The conveying rollers 36A and 40A are rotated by a driving force transmitted from a motor (not shown). The conveying roller pair 36 rotates while nipping the sheet S extending from the tensioner 45 in the conveying direction 8A, thereby feeding the sheet S in the conveying direction 8A along the conveying surface 43A. The conveying roller pair 40 rotates while nipping the sheet S fed from the conveying roller pair 36, thereby feeding the sheet S in the conveying direction 8A. Furthermore, the rotation of the conveying roller pair 36 and 40 pulls the sheet S from the sheet storage space 32C through the gap 42 toward the tensioner 45.

[0040] As shown in Fig. 2, a conveying 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 conveying path 43 extends substantially linearly along the conveying direction 8A, and is a space through which the sheet S can pass. Specifically, the conveying path 43 extends in the conveying direction 8A and the left-right direction 9 and extends along a conveying surface 43A that is long in the conveying direction 8A. In Fig. 2, the conveying surface 43A is indicated by a two-dot chain line that indicates the conveying path 43. The conveying path 43 is partitioned by a guide member (not shown), a head unit 38, a platen 51, and the like, which are positioned apart in the up-down direction 7.

[0041] The head unit 38 is located above the conveying path 43 and downstream of the pair of conveying rollers 36 in the conveying direction 8A. The head unit 38 has a head module 49 having a plurality of nozzles 38A. The plurality of nozzles 38A eject ink (an example of liquid) supplied from an ink subtank 47 downward toward the sheet S supported by the conveying belt 101. In this way, an image is recorded on the sheet S.

[0042] The platen 51 is located below the conveying path 43 and downstream of the conveying roller pair 36 in the conveying direction 8A. The platen 51 faces the head unit 38 below the head unit 38. The platen 51 has a conveying belt 101 and a support portion 104. The conveying belt 101 supports the sheet S that has been conveyed by the conveying roller pair 36 in the conveying direction 8A and is positioned directly below the head unit 38. The conveying belt 101 conveys the supported sheet S in the conveying direction 8A.

[0043] The mounting case 110 is located near the front and bottom ends of the lower housing 32 and is box-shaped and open toward the front. The ink tank 34 is inserted rearward into the mounting case 110. An ink needle 112 extending forward is located on a rear-facing end face 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 to the internal space 47A of the ink sub-tank 47 so that ink can flow through it. When the ink tank 34 is mounted in the mounting case 110, the ink needle 112 is inserted into an outlet (not shown) of the ink tank 34. This allows ink stored in the ink tank 34 to be supplied to the ink sub-tank 47 through the ink needle 112 and the ink tube 113. An ink supply valve 114 is located in the ink tube 113 and is capable of opening and closing the flow path of the ink tube 113. The opening and closing of the ink supply valve 114 is controlled by a controller (not shown).

[0044] The ink tank 34 stores ink. Ink is a liquid containing pigments and the like. The ink has a viscosity suitable for uniformly dispersing the pigments. The pigments determine the color of the ink. When the ink tank 34 is consumed, it is removed from the mounting case 110 and replaced with a new ink tank 34 that stores ink.

[0045] The ink subtank 47 is located above the ink tank 34. The ink subtank 47 stores ink supplied from the ink tank 34. A liquid supply path 61, a liquid discharge path 62, and an atmosphere communication path 64 are connected to the ink subtank 47. The liquid supply path 61 and the liquid discharge path 62 connect the ink subtank 47 and the head unit 38 so that ink can flow between them. One end of the atmosphere communication path 64 opens to the top of the internal space 47A of the ink subtank 47, and the other end opens to the internal space 31A of the upper housing 31.

[0046] A positive pressure pump 63 is disposed in the liquid supply path 61. The positive pressure pump 63 applies pressure to the ink in the liquid supply path 61 in a direction toward the head unit 38. An example of the positive pressure pump 63 is a diaphragm pump. The driving of the positive pressure pump 63 is controlled by a controller (not shown).

[0047] A negative pressure pump 65 is disposed in the atmosphere communication passage 64. The negative pressure pump 65 reduces the pressure in the internal space 47A of the ink subtank 47 by sucking air from the internal space 47A of the ink subtank 47. An example of the negative pressure pump 65 is a diaphragm pump. The air sucked by the negative pressure pump 65 is released into the atmosphere through the atmosphere communication passage 64. The operation of the negative pressure pump 65 is controlled by a controller (not shown).

[0048] A filter 66 is disposed in the liquid supply path 61. The filter 66 is located between the positive pressure pump 63 and the head unit 38. Note that the arrangement of the filter 66 is shown in a simplified manner in Figure 2.

[0049] As shown in FIG. 3 , the filter 66 includes a cylindrical housing 66A extending in the vertical direction 7, an outlet port 66B extending upward from the upper end of the housing 66A, and an inlet port 66C extending downward from the lower end of the housing 66A. The interior space of the housing 66A contains, for example, a mesh-type filter member having multiple holes with a predetermined inner diameter. The outlet port 66B opens upward. The inner diameter of the outlet port 66B is smaller than the inner diameter of the housing 66A. The inlet port 66C opens downward. The inner diameter of the inlet port 66C is smaller than the inner diameter of the housing 66A. When ink flows upward from the inlet port 66C into the interior space of the housing 66A and passes through the filter member, solids contained in the ink that are larger than the inner diameter of the holes in the filter member are captured by the filter member. This prevents solids contained in the ink from flowing into the head unit 38.

[0050] 2 and 3, liquid supply path 61 has a first connection portion 61A connected to outlet port 66B of filter 66, and a second connection portion 61B connected to inlet port 66C of filter 66. First connection portion 61A and second connection portion 61B are formed so as to be routed by tube 121 constituting a straight portion and pipe joint 122 constituting a bent portion.

[0051] Specifically, the first connecting portion 61A has a first connecting portion 611A (an example of a first portion), a first forward-facing portion 612A (an example of a second portion), a first downward-facing portion 613A (an example of a third portion), and a first rearward-facing portion 614A (an example of a fourth portion). The first connecting portion 611A is connected to an outlet port 66B of the filter 66. The first connecting portion 611A extends upward from the outlet port 66B. The first forward-facing portion 612A extends forward (an example of a lateral direction) from an upper end portion of the first connecting portion 611A. The first downward-facing portion 613A extends downward from a front end portion of the first forward-facing portion 612A to a position below an open end 66BB of the outlet port 66B. The first rearward-facing portion 614A extends rearward from a lower end portion of the first downward-facing portion 613A.

[0052] A branch flow path 67 is connected to the first backward portion 614A. The branch flow path 67 extends linearly upward from a connection position 67A (an example of a first position) connected to the upper side of the first backward portion 614A. The branch flow path 67 is formed by a tube 121. The branch flow path 67 communicates with the first backward portion 614A at the connection position 67A. A diameter R1 of the branch flow path 67 is larger than a diameter R2 of the first backward portion 614A. The connection position 67A is located below a first connection position 611AA (an example of a second position) where the first connection portion 611A is connected to the outlet port 66B. Specifically, the connection position 67A is located below an open end 66BB of the outlet port 66B. This ensures that the branch flow path 67 has a sufficient flow path length L1 from the connection position 67A to a pressure sensor 48 (described later).

[0053] A pressure sensor 48 is disposed at the upper end of the branch flow path 67. The pressure sensor 48 is located above the filter 66. The pressure sensor 48 detects the pressure of the air in the branch flow path 67 and outputs a detection signal to a controller (not shown).

[0054] The second connecting portion 61B has an upwardly facing portion 611B, a second backwardly facing portion 612B, a second downwardly facing portion 613B, a second forwardly facing portion 614B, and a second connecting portion 615B. The upwardly facing portion 611B extends upward in front of the inlet port 66C of the filter 66 from below the opening end 66CC of the inlet port 66C to above the opening end 66CC of the inlet port 66C. The second backwardly facing portion 612B extends rearward from the upper end of the upwardly facing portion 611B. The second downwardly facing portion 613B extends downward from the rear end of the second backwardly facing portion 612B to a position below the opening end 66CC of the inlet port 66C. The second forwardly facing portion 614B extends forward from the lower end of the second downwardly facing portion 613B to a position overlapping with the inlet port 66C in the up-down direction 7. The second connecting portion 615B extends upward from the front end of the second forward-facing portion 614B and is connected to the inlet port 66C. A second connecting position 615BB where the second connecting portion 615B is connected to the inlet port 66C of the filter 66 is an example of a third position. The upward-facing portion 611B, the second rearward-facing portion 612B, the second downward-facing portion 613B, the second forward-facing portion 614B, and the second connecting portion 615B of the second connecting part 61B are an example of a fifth portion.

[0055] [Ink supply from ink tank 34 to ink subtank 47] For example, when the ink tank 34 is mounted in the mounting case 110, the controller opens the ink supply valve 114 and drives the negative pressure pump 65. This reduces the pressure in the gas layer of the ink subtank 47, and the ink in the ink tank 34 is supplied to the ink subtank 47 through the ink tube 113 due to the pressure difference between the pressure in the ink subtank 47 and the pressure in the ink tank 34. By driving the negative pressure pump 65 for a certain period of time, a predetermined amount of ink is supplied from the ink tank 34 to the ink subtank 47. When the ink supply is complete, the ink supply valve 114 is closed.

[0056] [Image recording operation] Next, the operation of the image recording device 100 when an image is recorded on the sheet S drawn out from the roll body 37 will be described.

[0057] When the controller receives a command to record an image on the sheet S from an external device, such as the operation panel 44 or an information processing device connected to the image recording device 100 via a LAN or the like, the controller drives the positive pressure pump 63 and the negative pressure pump 65. This causes the pressure difference between the ink subtank 47 and the head unit 38 to circulate ink through the liquid supply channel 61 and the liquid discharge channel 62. At this time, the ink flows through the upward-facing portion 611B, the second backward-facing portion 612B, the second downward-facing portion 613B, the second forward-facing portion 614B, and the second connecting portion 615B of the second connecting portion 61B in this order, and then passes through the second connecting portion 61B. After passing through the second connecting portion 61B, the ink flows upward from the inlet port 66C of the filter 66 into the housing 66A and then flows upward from the outlet port 66B. At this time, if the ink contains solids larger than the inner diameter of the holes in the filter member, the solids are captured by the filter member.

[0058] The ink that has passed through the inside of the filter 66 flows through the first connection portion 611A, the first forward-facing portion 612A, the first downward-facing portion 613A, and the first backward-facing portion 614A of the first connection portion 61A in this order, and then passes through the first connection portion 61A. At this time, even if ink flows from the first backward-facing portion 614A into the branch flow path 67, the flow path length L1 between the connection position 67A and the pressure sensor 48 is sufficiently long (see FIG. 3), so that the ink is prevented from coming into contact with the pressure sensor. The ink that has passed through the first connection portion 61A reaches the head unit 38.

[0059] The ink that has reached the head unit 38 is ejected from the nozzles 38A toward the sheet S supported by the platen 51. This causes an image to be recorded on the sheet S. The sheet S with the image recorded thereon is cut to a predetermined size by a cutter or the like and is discharged from the discharge port 33.

[0060] Here, the ink pressure in the liquid supply path 61 can fluctuate due to factors such as ink consumption. For example, when the controller determines based on the detection signal of the pressure sensor 48 that the pressure in the liquid supply path 61 has become lower than a predetermined threshold, the controller controls the positive pressure pump 63 to increase the ejection pressure. Then, as ink is ejected from the head unit 38, the water level in the ink subtank 47 drops.

[0061] When the water level in the ink subtank 47 falls below a predetermined level, the controller opens the ink refill valve 114 based on a detection signal from a sensor installed in the ink subtank 47. As a result, ink is pumped from the ink tank 34 to the ink subtank 47 due to the pressure difference between the ink subtank 47, which has been reduced in pressure by the negative pressure pump 65, and the ink tank 34, which is at atmospheric pressure. When the water level in the ink subtank 47 reaches a predetermined level, the controller closes the ink refill valve 114 based on a detection signal from the sensor in the ink subtank 47. In this way, ink is refilled into the ink subtank 47.

[0062] [Effects of the embodiment] In the image recording device 100, the connection position 67A connected to the first backward-facing portion 614A is located below the position of the open end 66BB of the outlet port 66B (see FIG. 3), and therefore the flow path length L1 of the branch flow path 67 from the connection position 67A to the pressure sensor 48 is long. Therefore, even in the narrow space between the filter 66 and the head unit 38 in the up-down direction 7, the flow path length L1 between the first backward-facing portion 614A of the branch flow path 67 and the pressure sensor 48 is sufficiently ensured, and ink flowing through the first backward-facing portion 614A is prevented from entering the pressure sensor 48. As a result, the detection signal of the pressure sensor 48 is stabilized, and the pressure in the liquid supply path 61 is accurately detected.

[0063] In the image recording device 100, the branch flow path 67 extends linearly upward from the connection position 67A connected to the first backward portion 614A to the pressure sensor 48 (see FIG. 3), so the space occupied by the branch flow path 67 is small. Furthermore, the branch flow path 67 does not have the pipe joint 122 that forms a bent portion, so ink is less likely to rise upward through the pipe joint 122 than when the branch flow paths 67 are connected by the pipe joint 122. This makes it possible to prevent ink from entering the pressure sensor 48.

[0064] In the image recording device 100, the flow path length L1 from the connection position 67A of the branch flow path 67 to the pressure sensor 48 is longer by the distance L2 in the up-down direction 7 between the upper side of the first forward-facing portion 612A and the upper side of the first backward-facing portion 614A than when the branch flow path 67 is connected to the upper side of the first forward-facing portion 612A (see FIG. 3). This prevents ink from entering the pressure sensor 48.

[0065] In the image recording device 100, the direction in which ink flows in the first forward-facing portion 612A is opposite to the direction in which ink flows in the first backward-facing portion 614A (see FIG. 3), so the space required to arrange the liquid supply path 61 is small.

[0066] In the image recording device 100, the liquid supply path 61 has a tube 121 that forms a straight portion and a pipe fitting 122 that forms a bent portion, so that even if the tube 121 is made of a material that is difficult to bend, the liquid supply path 61 can be easily routed.

[0067] The image recording device 100 includes a liquid supply path 61 and a liquid discharge path 62 that connect the ink subtank 47 and the head unit 38, a positive pressure pump 63 disposed in the liquid supply path 61, and a negative pressure pump 65 that reduces the pressure in the internal space 47A of the ink subtank 47. Therefore, the ink is ejected from the nozzle 38A while circulating through the liquid supply path 61 and the liquid discharge path 62.

[0068] In the image recording device 100, when the filter 66 is disposed near the ink subtank 47, if an existing tube is to be connected to the inlet port 66C of the filter 66, the tube 121 cannot be connected to the inlet port 66C because the vertical distance between the inlet port 66C of the filter 66 and the ink subtank 47 is too close. In the image recording device 100, the second connection portion 61B connected to the inlet port 66C has an upward portion 611B, a second backward portion 612B, a second downward portion 613B, a second forward portion 614B, and a second connection portion 615B (see FIG. 3), and therefore extends upward and then bends back downward. Therefore, even if the vertical distance between the ink subtank 47 and the filter 66 is short, the second connection portion 61B can be connected to the inlet port 66C of the filter 66.

[0069] In the image recording device 100, the diameter R1 of the branch channel 67 is larger than the diameter R2 of the first backward portion 614A of the liquid supply channel 61 (see FIG. 3), so that liquid does not easily enter the branch channel 67 from the first backward portion 614A.

[0070] [Variations] In the image recording device 100, the branch flow path 67 extends upward in a straight line from the connecting position 67A to the pressure sensor 48, but may have a bent portion.

[0071] In the image recording device 100, the first connection portion 61A and the second connection portion 61B of the liquid supply path 61 are formed so as to be routed by a tube 121 constituting a straight portion and a pipe fitting 122 constituting a bent portion, but they may also be formed so as to be routed by a single flexible tube.

[0072] In the image recording device 100, the diameter R1 of the branch flow path 47 is larger than the diameter R2 of the first backward portion 614A of the liquid supply path 61, but may be equal to or smaller than the diameter R2 of the first backward portion 614A.

[0073] In the image recording device 100, the detection signal of the pressure sensor 48 is used by the controller to control the pressure of the positive pressure pump 63, but it may also be used for other purposes. For example, the detection signal of the pressure sensor 48 may be used to control the opening of an air release valve (not shown) connected to the ink subtank 47 when the negative pressure in the internal space 47A of the ink subtank 47 exceeds a predetermined threshold. Also, a pressure sensor may be provided to detect the pressure inside the ink subtank 47, and the detection signal of this pressure sensor may be used to control the opening of the air release valve (not shown). [Explanation of symbols]

[0074] 38···Head unit 47 Ink subtank 47A...Internal space 48 Pressure sensor 61...Liquid supply path 62...Liquid drain path 63 Positive pressure pump 65 Negative pressure pump 66···Filter 66B Outlet port 66C Inlet port 67 Branch flow path 67A...Connection position 121...Tube 122···Pipe fitting 611A···First connection 611AA···First connection position 611B···Upward part 612A···First forward-facing section 612B Second rear-facing section 613A···First downward section 613B···Second downward section 614A···First rear-facing section 614B Second forward-facing section 615B···Second connection part 615BB···Second connection position R1 diameter R2...diameter

Claims

1. a tank for storing a liquid; a head that ejects the liquid supplied from the tank; a liquid supply path connecting the tank and the head; a filter disposed in the liquid supply path upstream of the head; a branch flow path connected between the head and the filter in the liquid supply path; a pressure sensor disposed in the branch flow path, The pressure sensor is located above the filter, A liquid ejection device, wherein a first position where the branch flow path is connected in the liquid supply path is located below a second position where the branch flow path is connected to the outlet port of the filter.

2. 2. The liquid ejection device according to claim 1, wherein the branch flow path extends linearly upward from the first position to the pressure sensor.

3. The liquid supply channel is a first portion extending upward from an outlet port of the filter; a second portion extending from the first portion in a horizontal direction intersecting the vertical direction; a third portion extending downward from the second portion; 3. The liquid ejection device according to claim 1, further comprising: a fourth portion extending laterally from the third portion to the first position.

4. 4. The liquid ejection device according to claim 3, wherein the direction in which the liquid flows through the second portion is opposite to the direction in which the liquid flows through the fourth portion.

5. 5. The liquid ejection device according to claim 1, wherein the liquid supply path has a tube that forms a straight portion and a pipe joint that forms a bent portion.

6. a liquid discharge path connecting the tank and the head; a positive pressure pump disposed in the liquid supply path; 6. The liquid ejection device according to claim 1, further comprising a negative pressure pump that reduces the pressure in the internal space of the tank.

7. 7. The liquid ejection device according to claim 1, wherein the liquid supply path has a fifth portion that extends upward and then turns back downward, upstream of a third position where the liquid supply path is connected to the inlet port of the filter.

8. 8. The liquid ejection device according to claim 1, wherein the branch flow path has a diameter larger than that of the liquid supply path.

Images