CN110356110B

CN110356110B - Liquid supply unit and liquid ejection device

Info

Publication number: CN110356110B
Application number: CN201910235099.6A
Authority: CN
Inventors: 江藤大辅
Original assignee: Kyocera Document Solutions Inc
Current assignee: Kyocera Document Solutions Inc
Priority date: 2018-03-26
Filing date: 2019-03-26
Publication date: 2021-10-08
Anticipated expiration: 2039-03-26
Also published as: CN110356110A

Abstract

The invention provides a liquid supply unit and a liquid ejecting apparatus. The liquid supply unit supplies liquid from a liquid storage container storing a predetermined liquid to a liquid ejecting head that ejects the liquid. The liquid supply unit includes a pressure chamber, a first supply passage, a second supply passage, a bypass supply passage, and a pressurizing mechanism. The pressure chamber may store a liquid. The first supply passage communicates the liquid accommodating container with the pressure chamber. The second supply passage communicates the liquid ejection head with the pressure chamber. The bypass supply passage has an upstream end in a liquid supply direction connected to the first supply passage and a downstream end merging with the second supply passage. The pressurizing mechanism is disposed in the bypass supply passage and pressurizes the liquid flowing through the bypass supply passage. Accordingly, in the liquid supply unit using the pressure fluctuation of the pressure chamber storing the liquid, the pressurization cleaning of the liquid ejecting head can be easily performed.

Description

Liquid supply unit and liquid ejecting apparatus

Technical Field

The present invention relates to a liquid supply unit that supplies liquid stored in a liquid storage container to a liquid ejecting head, and a liquid ejecting apparatus to which the liquid supply unit is applied.

Background

For example, in an ink jet printer, a liquid ejecting head that ejects a small amount of ink (liquid) to a printing object is used. Ink is supplied from an ink cartridge (liquid storage container) storing ink to the liquid ejecting head through a predetermined supply path. In the related art, in a case where ink is supplied from an ink cartridge to a liquid ejecting head by a head difference, a liquid ejecting apparatus is known in which a liquid supply unit (valve unit) having a pressure chamber in which an ejection orifice of the liquid ejecting head is set to a negative pressure is disposed in the supply passage. By providing the liquid supply unit that forms the negative pressure, ink is prevented from dripping from the ejection holes without restriction even when ink is supplied by a water head difference.

In a conventional liquid supply unit, a portion of a pressure chamber that is made negative in pressure is defined by a flexible film, and a pressing plate (pressure receiving plate) attached to the flexible film directly presses a movable valve. The movable valve is biased in a direction opposite to the pressing direction by a biasing member. When the negative pressure of the pressure chamber is increased by sucking out the ink from the liquid ejecting head, the movable valve is pushed and moved by the pushing plate in accordance with the displacement of the flexible film, and the ink supply channel to the pressure chamber is opened to allow the ink to flow in. When the degree of negative pressure in the pressure chamber decreases due to the inflow of ink, the movable valve moves in the opposite direction by the biasing force of the biasing member, and the pressure chamber returns to a sealed state.

In the liquid ejecting head, in order to eliminate or prevent the clogging of the ink ejection ports, it is necessary to perform a cleaning process of the ink ejection ports. In this case, if the cleaning process is performed by externally installing a suction pump or the like on the liquid ejecting head side, the apparatus configuration becomes complicated, and therefore, it is preferable to perform a pressurized cleaning in which the high-pressure ink is supplied from the liquid supply unit to the ink ejection port and ejected. However, as described above, in the liquid supply unit of the type using the pressure fluctuation of the pressure chamber, a structure capable of easily performing the pressure purge has not been proposed in practice.

Disclosure of Invention

The invention aims to provide a liquid supply unit which can easily perform pressurization and cleaning of a liquid ejecting head in the liquid supply unit using pressure variation of a pressure chamber for storing liquid and a liquid ejecting apparatus using the liquid supply unit.

A liquid supply unit according to an aspect of the present invention supplies a liquid from a liquid storage container storing a predetermined liquid to a liquid ejecting head ejecting the liquid, the liquid supply unit including: a pressure chamber capable of storing the liquid; a first supply passage that communicates the liquid accommodating container with the pressure chamber; a second supply passage that communicates the liquid ejection head with the pressure chamber; a bypass supply passage including one end connected to the first supply passage and the other end connected to the second supply passage and including a pipe line directly connecting the first supply passage and the second supply passage without passing through the pressure chamber; and a pressurizing mechanism that is disposed in the bypass supply passage and pressurizes the liquid flowing through the bypass supply passage, the pressurizing mechanism having one end as an upstream end in a liquid supply direction in the bypass supply passage and the other end as a downstream end to supply the liquid from the first supply passage to the second supply passage, the second supply passage having a starting end portion connected to the pressure chamber, the liquid supply unit further including a backflow prevention mechanism that is disposed in the second supply passage between a junction of the second supply passage and the other end of the bypass supply passage and the starting end portion and prevents the liquid pressurized by the pressurizing mechanism from flowing backward toward the pressure chamber.

A liquid ejecting apparatus according to another aspect of the present invention includes: a liquid ejecting head that ejects a specified liquid; and the liquid supply unit that supplies the liquid from a liquid storage container that stores the liquid to the liquid ejecting head.

According to the present invention, the pressure purging of the liquid ejection head can be performed easily.

Drawings

Fig. 1 is a perspective view showing an external appearance of an ink jet printer to which the present invention is applied.

Fig. 2 is a sectional view taken along line II-II of fig. 1.

Fig. 3 is a front view of the inkjet printer with the cover removed.

Fig. 4 is an overall perspective view of a holder mounted on the inkjet printer.

Fig. 5 is a perspective view showing one liquid supply unit and one head unit according to the first embodiment.

Fig. 6(a) and (B) are views schematically showing a cross section of the head unit in the front-rear direction, fig. 6(a) showing a state in which the print mode is executed, and fig. 6(B) showing a state in which the circulation mode is executed.

Fig. 7 is a block diagram of the liquid supply system according to the present embodiment, and is a diagram showing a state in which the print mode is executed.

Fig. 8 is a block diagram showing a state in which the loop mode is executed.

Fig. 9(a) is a diagram showing a state in which the pressure-increasing purge mode is executed, and fig. 9(B) is a diagram showing a state in which the pressure-decreasing mode is executed.

Fig. 10(a) and (B) are perspective views of the liquid supply unit, fig. 10(a) is a perspective view seen from the first chamber side, and fig. 10(B) is a perspective view seen from the second chamber side.

Fig. 11 is a perspective view of the liquid supply unit in a state where the sealing film on the first chamber side is detached.

Fig. 12(a) to (C) are perspective views of the liquid supply unit in a state where the atmospheric pressure detection membrane on the second chamber side is detached.

Fig. 13 is an exploded perspective view of the liquid supply unit.

Fig. 14(a) is a perspective view of the pushing member, and fig. 14(B) is a perspective view of the pushing member with a different view direction.

Fig. 15(a) is a perspective view of the opening/closing valve, and fig. 15(B) is an exploded perspective view of the opening/closing valve.

Fig. 16(a) is a cross-sectional view taken along line XVI-XVI in fig. 10(a) and shows a state in which the opening/closing valve is in the closed position, and fig. 16(B) is an enlarged view of a portion a1 in fig. 16 (a).

Fig. 17(a) is a cross-sectional view corresponding to fig. 16(a) and showing a state in which the opening/closing valve is in an open position, and fig. 17(B) is an enlarged view of a portion a2 of fig. 17 (a).

Fig. 18(a) and (B) are schematic diagrams for explaining the positional relationship between the pivot point of the pressing member and the pressing portion and the operation of the pressing member.

Fig. 19(a) is an exploded perspective view of the filter chamber, and fig. 19(B) is a front-rear sectional view of the filter chamber.

Fig. 20(a) and (B) are perspective views of the lever member, and fig. 20(C) is an exploded perspective view of the lever member.

Fig. 21(a) and (B) are perspective views of the pressing member, the opening/closing valve, and the rod member.

Fig. 22(a) is a cross-sectional view showing a state before the lever member operates, and fig. 22(B) is a cross-sectional view showing a state in which the exhaust gas is performed by the operation of the lever member.

Fig. 23(a) is a perspective view of the exhaust mechanism portion corresponding to the state of fig. 22(a), and fig. 23(B) is a perspective view showing an operation of the lever member.

Fig. 24(a) is a perspective view showing the operation of the lever member, and fig. 24(B) is a perspective view of the exhaust mechanism portion corresponding to the state of fig. 22 (B).

Fig. 25 is a front-rear direction sectional view of the liquid supply unit.

Fig. 26 is an exploded perspective view of the backflow prevention mechanism.

Fig. 27(a) is a perspective view of the backflow prevention mechanism, showing a state in which the ball opens the valve line, fig. 27(B) is a view showing a state in which the ball closes the valve line, and fig. 27(C) is a perspective view of the branch head.

Fig. 28(a) and (B) are enlarged views of a portion a3 of fig. 25, fig. 28(a) is a sectional view showing a state of the backflow prevention mechanism in the print mode, and fig. 28(B) is a sectional view showing a state of the backflow prevention mechanism in the pressure purge mode.

Fig. 29(a) is a sectional view of a state where the communication port is closed by the umbrella valve, and fig. 29(B) is a sectional view of a state where the communication port is opened by the umbrella valve.

Fig. 30 is a perspective view showing the flow of ink in the print mode.

Fig. 31 is a perspective view showing the flow of ink in the pressure purge mode.

Fig. 32 is a perspective view showing the flow of ink in the circulation mode.

Fig. 33(a) is a front view, fig. 33(B) is a side view, and fig. 33(C) is a plan view of a liquid supply unit according to the second embodiment.

Fig. 34 is a perspective view showing an internal structure of a liquid supply unit according to a second embodiment.

Fig. 35 is a perspective view showing an internal structure of a liquid supply unit according to a second embodiment.

Fig. 36(a) is an exploded perspective view of the liquid supply unit, and fig. 36(B) is an exploded perspective view of the liquid supply unit with a different view direction.

Fig. 37 is a perspective view of the main body of the liquid supply unit in an exploded perspective view of the backflow prevention mechanism associated with the liquid supply unit.

Fig. 38(a) is a perspective view of a pushing member according to a second embodiment, and fig. 38(B) is a perspective view of a pushing member with a different view direction.

Fig. 39(a) and (B) are schematic diagrams for explaining the operation of the pressing member using the lever ratio.

Fig. 40(a) is a perspective view of the backflow prevention mechanism of the second embodiment, showing a state in which the ball sets the valve line open, fig. 40(B) is a view of a state in which the ball sets the valve line closed, and fig. 40(C) is a perspective view of the branch head.

Fig. 41(a) is a cross-sectional view showing a state of the backflow prevention mechanism in the print mode, and fig. 41(B) is an enlarged view of a portion a4 of fig. 41 (a).

Fig. 42(a) is a cross-sectional view showing a state of the backflow prevention mechanism in the pressure purge mode, and fig. 42(B) is an enlarged view of a portion a5 of fig. 42 (a).

Fig. 43(a) is a perspective view of an opening/closing valve according to a modification, and fig. 43(B) is an exploded perspective view of the opening/closing valve.

Detailed Description

[ integral Structure of Printer ]

An embodiment of the present invention will be described below with reference to the drawings. First, an ink jet printer to which the liquid supply unit or the liquid ejecting apparatus according to the present invention is applied will be described. Fig. 1 is a perspective view showing an external appearance of an ink jet printer 1 according to an embodiment, fig. 2 is a cross-sectional view taken along line II-II of fig. 1, and fig. 3 is a front view of the printer 1 with a cover 102 removed. Note that, although the directions of the front-back, the left-right, and the up-down are shown in fig. 1 to 3 and the drawings shown later, this is for convenience of explanation only, and is not intended to limit the directions.

The printer 1 (liquid ejecting apparatus) is a printer that performs printing processing such as printing and printing by an ink jet method on various sheets W (work targets) such as paper sheets of various sizes, resin sheets, and cloths, and is particularly suitable for printing processing on a long sheet of large size. The printer 1 includes a base frame 101 with casters and an apparatus main body 11 that is placed on the base frame 101 and executes the printing process.

The apparatus main body 11 includes a sheet conveying path 12, conveying rollers 13, a pinch roller unit 14, and a holder 2. The sheet conveyance path 12 is a conveyance path extending in the front-rear direction, and conveys a sheet W to be subjected to a printing process from the rear side into the apparatus main body 11 and from the front side. The conveying roller 13 is a roller that extends in the left-right direction and generates a driving force to intermittently feed out the sheet W in the sheet conveying path 12. The pinch roller unit 14 includes pinch rollers that are arranged to face the conveying rollers 13 from above and form a conveying nip together with the conveying rollers 13. The pinch roller unit 14 is disposed in plurality at predetermined intervals in the left-right direction.

The carriage 2 is a moving body that is mounted on the base frame 101 and reciprocates in the left-right direction to perform a printing process on a sheet W. A rack guide 15 is provided upright on the rear side of the base frame 101 so as to extend in the left-right direction, and the rack guide 15 includes a guide rail for guiding the reciprocating movement of the rack 2. A timing belt 16 is incorporated in the rack guide 15 so as to be movable in the left-right direction in the circumferential direction. The holder 2 has a fixing portion to the timing belt 16, and moves in the left-right direction while being guided by the guide rail in accordance with the circumferential movement of the timing belt 16 in the normal rotation or reverse rotation.

The printing process is performed in such a manner that: the conveying roller 13 and the pinch roller unit 14 intermittently convey the sheet W, and while the sheet W is stopped, the carriage 2 moves in the left-right direction to perform print scanning (ejection of ink onto the sheet W) on the sheet W. Further, a platen 121 (fig. 2) having a function of sucking the sheet W is disposed below the passage of the carriage 2 in the sheet conveying path 12. When the print processing is performed, the carriage 2 executes print scanning while the sheet W is attracted to the platen 121.

The device body 11 is covered with a cover 102. A side stand 103 is disposed in a right region of the outer cover 102. A fixed cartridge holder 17 is housed inside the side table 103, and the cartridge holder 17 holds an ink cartridge IC (fig. 5 and 6) that stores ink (a predetermined liquid) for a printing process.

The front portion of the side stand 103 is a rack retreat region 104 which becomes an retreat space of the rack 2. As shown in fig. 3, a left frame 105 and a right frame 106 are provided upright on the base frame 101 at intervals corresponding to the sheet conveying path 12 in the left-right direction. The area between these left and

right frames

105, 106 is a print area P (processing area) where the print processing can be performed if distinguished by a job area. The carriage guide 15 has a left-right width longer than the printing area P, and the carriage 2 is movable to the right outside of the printing area P. The right end side of the holder guide 15, that is, the area right adjacent to the printing area P is a maintenance area M. When the printing process is not executed, the carriage 2 is retracted to the maintenance area M (carriage retraction area 104). Further, a pressure cleaning process described later is also performed in the holder retreat region 104.

A feeding portion 107 for receiving a roll Wa, which is a wound body of a sheet W to be printed, is provided on the rear side of the base frame 101. Further, a winding unit 108 that houses a winding body of the sheet W after the printing process, i.e., a winding roll Wb, is provided on the front side of the base frame 101. The winding unit 108 includes a not-shown drive source for rotationally driving a winding shaft of the winding roll Wb, and winds the sheet W while applying a predetermined tension to the sheet W by the tension roller 109.

[ Structure of holder including liquid ejecting head according to first embodiment ]

Fig. 4 is an overall perspective view of the stand 2. A head unit 21 (liquid ejecting head) according to the first embodiment that ejects ink (liquid) onto a sheet W and a liquid supply unit 3 that supplies ink from an ink cartridge IC (fig. 5) to the head unit 21 are mounted on the carriage 2. Fig. 4 shows an example in which 2

head units

21 and 8 liquid supply units 3 are mounted on the stand 2. That is, 4 liquid supply units 3 are provided for 1 head unit 21 to supply cyan, magenta, yellow, and black inks. Further, a method may be employed in which the liquid supply units 3 are filled with different color inks, and up to 8 color inks are discharged from 2 head units 21.

The carriage 2 includes a head unit 21 and a carriage frame 20 that holds the head unit 21. The rack frame 20 includes: a lower frame 201 located at the lowermost position; an upper frame 202 disposed above the lower frame 201 with a space therebetween; a frame 203 assembled to the upper surface of the upper frame 202; and a rear frame 204 mounted behind the upper frame 202. The lower frame 201 and the upper frame 202 are coupled by a coupling strut 205 extending in the vertical direction. A ball screw mechanism, not shown, is mounted on the rear frame 204, and a nut portion driven by the ball screw is attached to the lower frame 201. The rear frame 204 is provided with a guide support 206 extending in the vertical direction. By the driving of the ball screw mechanism, the coupled body of the lower frame 201 and the upper frame 202 can move in the vertical direction while being guided by the guide support 206. That is, the main body portion of the cradle 2 is movable in the up-down direction with respect to the back frame 204. A rear plate 207 to which an upstream end 331 of an upstream pipe 33 described later is attached is erected on the rear frame 204.

The head unit 21 is mounted on the lower frame 201. Since the main body portion of the holder 2 is vertically movable as described above, the vertical height position of the head unit 21 with respect to the sheet W can be adjusted. The upper frame 202 carries the liquid supply unit 3. The 8 liquid supply units 3 are supported by the upper frame 202 in a manner arranged in the left-right direction in the rack 203. The rear frame 204 includes a guided portion guided by the guide rail of the rack guide 15, a fixing portion to the timing belt 16, and the like.

Fig. 5 is a perspective view showing one liquid supply unit 3 and one head unit 21 according to the first embodiment. The liquid supply unit 3 includes: a main body 30 provided with a tank portion 31 and a pump portion 32; an upstream pipe 33(a part of the first supply passage) disposed on an upstream side in an ink supply direction (liquid supply direction) of the main body 30; a downstream pipe 34 (a part of the second supply passage) disposed on the downstream side of the main body 30; and a return tube 35 (return path) serving as a path for returning ink from the head unit 21 side to the liquid supply unit 3 side; a monitor tube 36; and a bypass pipe 32P (bypass supply passage).

The tank portion 31 is a region that forms a space that temporarily stores ink supplied to the head unit 21 in a negative pressure environment. The pump section 32 is a region in which a pump 9 (pressurizing mechanism; fig. 7 to 9) is housed, and the pump 9 is operated at the time of a pressure reduction process for forming the negative pressure environment, at the time of a pressure removal process for cleaning the head unit 21 (ink ejecting section 22), and at the time of a circulation process for circulating ink between the head unit 21 and the liquid supply unit 3.

The upstream pipe 33 is a supply pipe for communicating the tank portion 31 (second chamber 42) and the ink cartridge IC (liquid storage container). The upstream end 331 of the upstream pipe 33 is connected to the end of the pipe 330 extending from the ink cartridge IC, and the downstream end 332 is connected to the inlet portion of the tank portion 31. A supply valve 33V that functions to open and close the upstream pipe 33 is attached to the pipe 330. If the supply valve 33V is opened, ink can be supplied from the ink cartridge IC to the tank portion 31, and if the supply valve 33V is closed, the supply is disabled.

The downstream pipe 34 is a supply pipe that communicates the tank portion 31 (second chamber 42) and the head unit 21. The upstream end 341 of the downstream pipe 34 is connected to the outlet portion of the tank portion 31 via a backflow prevention mechanism 38 described later, and the downstream end 342 is connected to the head unit 21. The return pipe 35 is a pipe for communicating the head unit 21 and the tank portion 31 (second chamber 42). The upstream end 351 of the return pipe 35 is connected to the head unit 21, and the downstream end 352 is connected to the tank portion 31. A clamp 35V for opening and closing the return pipe 35 is attached to the return pipe 35. Fig. 5 shows a state in which the clamp 35V crushes the return pipe 35 and the return pipe 35 is closed. The monitor tube 36 is a tube for indicating the level of ink in the tank 31. The bypass pipe 32P is a pipe for feeding ink to the downstream pipe 34 without passing through the negative pressure environment (second chamber 42) of the tank portion 31. The bypass pipe 32P includes a bypass upstream pipe BP1 disposed on the upstream side of the pump section 32 and a bypass downstream pipe BP2 disposed on the downstream side.

The head unit 21 includes an ink ejecting section 22, a control unit section 23, an end pipe 24, and a recovery pipe 25. The ink discharge portion 22 is a nozzle portion that discharges ink droplets toward the sheet W. As a method of ejecting ink droplets in the ink ejecting section 22, a piezoelectric method using a piezoelectric element, a thermal method using a heating element, or the like can be applied. The control unit section 23 includes a control board for controlling the piezoelectric element or the heating element provided in the ink ejecting section 22, and controls the ink droplet ejecting operation from the ink ejecting section 22.

The end pipe 24 is a pipe connecting the downstream end 342 of the downstream pipe 34 and the ink ejection portion 22. The downstream end 342 is a hat-type spigot and is attached to the upper end fitting portion of the end pipe 24 in a single operation. The recovery pipe 25 is a pipe connecting the ink ejecting section 22 and the upstream end 351 of the return pipe 35. The recovery tube 25 is also used to discharge the preservation solution sealed in the liquid supply unit 3 at the time of initial use. In the initial use, the downstream end 342 of the downstream pipe 34 is attached to the upper end fitting portion of the end pipe 24, and the recovery pipe 25 is connected to another pipe, so that the storage space for the storage liquid is opened to perform the operation of discharging the storage liquid.

Fig. 6a and B are views schematically showing a cross section of the head unit 21 in the front-rear direction, fig. 6a showing a state in which the clip 35V is closed (print mode), and fig. 6B showing a state in which the clip 35V is opened (circulation mode). The ink discharge portion 22 includes a plurality of ink discharge holes 22H (liquid discharge ports) through which ink is discharged toward the sheet W. The head unit 21 includes individual channels 26 for individually supplying ink to the ink ejection holes 22H and a common channel 27 for supplying ink to the individual channels 26.

The common channel 27 is an ink channel extending in the horizontal direction. The upstream end of each individual passage 26 communicates with the common passage 27. The downstream end 342 of the downstream pipe 34 communicates with the upstream side of the common passage 27 through the end pipe 24. The upstream end 351 of the return pipe 35 communicates with the downstream side of the common passage 27 through the recovery pipe 25. In other words, the upstream side of the common passage 27 communicates with the tank portion 31 (second chamber 42) through the downstream pipe 34, and the downstream side of the common passage 27 communicates with the tank portion 31 (second chamber 42) through the return pipe 35.

As shown in fig. 6(a), if ink is supplied from the downstream pipe 34 to the head unit 21 in a state where the return pipe 35 is set to be closed by the clip 35V, the ink is ejected from the ink ejection hole 22H through the common channel 27 and the individual channels 26. On the other hand, as shown in fig. 6(B), in a state where the clip 35V is opened and the return pipe 35 is set to be opened, if ink is supplied from the downstream pipe 34 to the head unit 21, the ink is returned to the tank portion 31 exclusively through the return pipe 35. At this time, if the return pipe 35 is made negative in pressure, the ink does not leak from the ink ejection hole 22H.

[ outline of liquid supply System ]

In the present embodiment, the ink cartridge IC is disposed above the head unit 21, and the head unit 21 is supplied with ink by a water head difference. In the case of supplying ink using a water head difference, if the supply is performed under normal pressure, the ink is always discharged from the ink discharge portion 22 of the head unit 21. Therefore, it is necessary to provide a negative pressure forming portion for creating a negative pressure environment in the ink supply path and set the ink ejecting portion 22 to an appropriate negative pressure. The tank portion 31 of the liquid supply unit 3 functions as the negative pressure forming portion.

Fig. 7 is a block diagram schematically showing a liquid supply system used in the holder 2 of the present embodiment. The ink cartridge IC is disposed at a position higher than the ink ejecting section 22 by a height h. The height h becomes a water head difference by which the ink of the ink cartridge IC is supplied to the head unit 21. The liquid supply unit 3 is assembled in the middle of the ink supply path between the ink cartridge IC and the head unit 21. The tank portion 31 of the liquid supply unit 3 includes: a first chamber 41(a part of the upstream chamber/first supply passage) which becomes a pressure higher than atmospheric pressure by the water head difference; and a second chamber 42 (pressure chamber) disposed on the downstream side in the ink supply direction with respect to the first chamber 41 and set to a negative pressure. The first chamber 41 is a chamber that is not subjected to a negative pressure operation, and becomes a chamber to which a pressure P based on the water head difference is applied in addition to atmospheric pressure. When the density of water (the ink can be treated as equal to the water in density) is ρ, the gravitational acceleration is g, and the head difference is h, the pressure P is expressed by P ═ ρ gh [ Pa ]. The first chamber 41 communicates with the ink cartridge IC through the upstream pipe 33. The second chamber 42 communicates with the ink ejection portion 22 through the downstream pipe 34.

An opening/closing valve 6 (opening/closing member) connected to the pressing member 5 is disposed on a wall surface defining the first chamber 41 and the second chamber 42. Further, a part of the wall portion defining the second chamber 42 is formed by the atmospheric pressure detecting film 7 (flexible film member). If the inside of the second chamber 42 has a negative pressure exceeding a predetermined threshold value, the atmospheric pressure detection film 7 detects atmospheric pressure and displaces. This displacement force is applied to the pressing member 5, and the posture of the connected opening/closing valve 6 is changed from the closed posture to the open posture, so that the first chamber 41 and the second chamber 42 are in a state of communication. The ink supply path in the normal printing process is a path passing through the upstream pipe 33, the first chamber 41, the second chamber 42, and the downstream pipe 34. In addition, the bypass pipe 32P is provided to short-circuit the first chamber 41 and the downstream pipe 34 without passing through the second chamber 42. The upstream end of the bypass pipe 32P is connected to the upstream pipe 33 via the first chamber 41, and the downstream end merges with the downstream pipe 34 (merging portion a). A pump 9 that can rotate forward and backward is disposed in the bypass pipe 32P.

Fig. 7 is a diagram showing a state of a print mode in which the liquid supply system is executed to perform print processing. In this printing mode, the supply valve 33V of the upstream pipe 33 is opened, and the clamp 35V of the return pipe 35 is closed. In the print mode, the first chamber 41 and the second chamber 42 are filled with a predetermined amount of ink, and the second chamber 42 is set to a predetermined negative pressure. The pressure of the first chamber 41 is atmospheric pressure + ρ gh [ Pa ] based on the water head difference as described above, and the ink can be supplied from the ink cartridge IC by the water head difference as needed. As a basic setting of the print mode, the opening/closing valve 6 is in the closed position to set the second chamber 42 to the negative pressure, and the first chamber 41 and the second chamber 42 are in the isolated state. The pump 9 is in a stopped state. The pump 9 is a tube pump, and when the pump 9 is stopped, the bypass tube 32P is in a closed state. Therefore, the downstream pipe 34 and the ink ejecting portion 22 are also maintained in a negative pressure state.

In order to smoothly fill the second chamber 42 with ink, the second chamber 42 is provided with an air discharge mechanism 37. At the time of initial use, after maintenance, or the like, a predetermined amount of ink needs to be initially filled into the second chamber 42. The air discharge mechanism 37 temporarily connects the second chamber 42 set to the negative pressure atmosphere to the atmosphere (discharges air in the second chamber 42), and promotes the initial filling. Further, the ink contained in the second chamber 42 may be heated to generate bubbles. The air discharge mechanism 37 is also used to remove air generated by the air bubbles from the second chamber 42.

If the head unit 21 is operated and the ink ejecting section 22 ejects ink droplets, the ink in the second chamber 42 is consumed, and the degree of negative pressure in the second chamber 42 also increases along with this. That is, the ink ejecting section 22 performs an operation of sucking ink from the second chamber 42 in a state isolated from the atmosphere every time ink droplets are ejected, and increases the negative pressure degree of the second chamber 42. Then, if the second chamber 42 becomes a negative pressure exceeding a predetermined threshold value with a decrease in the ink in the second chamber 42, the atmospheric pressure detection film 7 detects the atmospheric pressure and displaces as described above. By this displacement force, the posture of the opening/closing valve 6 is changed from the closed posture to the open posture by the pressing member 5, and the first chamber 41 and the second chamber 42 are brought into a communicating state. Therefore, the ink flows from the first chamber 41 to the second chamber 42 by the pressure difference between the two chambers.

The negative pressure in the second chamber 42 gradually decreases and approaches the atmospheric pressure as the ink flows into the second chamber 42. At the same time, the displacement force applied from the atmospheric pressure detection membrane 7 to the pressing member 5 also gradually decreases. If the second chamber 42 becomes a negative pressure lower than the predetermined threshold value, the opening/closing valve 6 returns to the closed position, and the first chamber 41 and the second chamber 42 are isolated from each other again. At this time, ink is replenished from the ink cartridge IC to the first chamber 41 based on the water head difference in accordance with the amount of ink flowing from the first chamber 41 into the second chamber 42. In the print mode, such an operation is repeated.

The liquid supply system of the present embodiment can execute a circulation mode, a pressure purge mode, and a pressure reduction mode in addition to the above-described printing mode. The circulation mode is a mode in which ink is circulated by using the return pipe 35 to remove air from the ink channels (individual channels 26 and common channel 27) existing in the head unit 21. The pressure purge mode is a mode in which high-pressure ink is supplied to the ink ejecting portion 22 and ejected in order to eliminate or prevent ink clogging in the ink ejecting portion 22. The decompression mode is a mode for setting the second chamber 42 in the normal pressure state to the predetermined negative pressure at the time of initial use, after maintenance, or the like.

Fig. 8 is a block diagram showing a state in which the loop mode is executed. In this circulation mode, the supply valve 33V is closed and the upstream pipe 33 is in a closed state, while the clamp 35V is opened and the return pipe 35 is in an open state. The pump 9 disposed in the bypass pipe 32P is driven in the normal direction. As shown in fig. 6(a), the upstream end 351 of the return pipe 35 communicates with the downstream end of the common passage 27 in the head unit 21. On the other hand, the downstream end 352 of the return pipe 35 communicates with the first chamber 41. The downstream end 352 of the return pipe 35 is also in communication with the second chamber 42 via the first chamber 41 and the on-off valve 6, which are in direct communication with each other.

When the pump 9 is driven in the normal rotation in the circulation mode, the ink circulates through a circulation path formed by the bypass downstream pipe BP2, the downstream pipe 34 on the downstream side of the junction a, the common passage 27 in the head unit 21, the return pipe 35, and the bypass upstream pipe BP 1. At this time, since the supply valve 33V is closed, the return pipe 35 and the common channel 27 are brought into a negative pressure by the ink suction operation of the pump 9. Therefore, the ink does not leak from the ink ejection hole 22H. By executing the circulation mode, the air that has entered the head unit 21 side can be recovered to the liquid supply unit 3 (first chamber 41). Accordingly, air is not accumulated in the individual channels 26 and the ink ejection holes 22H, and defective ejection of ink can be suppressed. Further, the air recovered in the first chamber 41 can be transferred to the second chamber 42 through the opening/closing valve 6. Then, the air is released to the outside by the air release mechanism 37.

Fig. 9(a) is a diagram showing a state in which the pressure purge mode is executed. In the pressure purge mode, the pump 9 is driven in the normal rotation. The clamp 35V is closed. By the normal rotation driving of the pump 9, the ink bypasses the second chamber 42 and directly flows from the upstream pipe 33 to the downstream pipe 34 via the first chamber 41 and the bypass pipe 32P. That is, the ink pressurized by the pump 9 is supplied to the ink ejecting section 22. Accordingly, the ink is forcibly discharged from the ink discharging portion 22, and the ink discharging portion 22 is cleaned. The same operation as in the pressure purge mode is also performed when the preservation liquid sealed in the liquid supply unit 3 is discharged at the time of initial use.

As described above, in the present embodiment, a path that passes through the bypass pipe 32P is provided in the liquid supply path from the ink cartridge IC to the head unit 21 in parallel with a path that passes through the second chamber 42. The pump 9 is disposed in the bypass pipe 32P. Therefore, the pressurized ink can be supplied to the head unit 21 using the bypass tube 32P without passing through the second chamber 42 having the negative pressure mechanism. That is, the operation of pressurizing and purging the ink discharge portion 22 can be easily performed with a simple configuration in which the bypass pipe 32P and the pump 9 are arranged in parallel with the second chamber 42.

Further, when the pressure purge mode is executed, the backflow prevention mechanism 38 is provided to prevent the pressurized ink from flowing backward into the second chamber 42 through the downstream pipe 34. The backflow prevention mechanism 38 is disposed in the downstream pipe 34 on the upstream side of the junction a between the downstream pipe 34 and the downstream end of the bypass pipe 32P. Since the upstream side of the junction a of the downstream pipe 34 is closed by the backflow prevention mechanism 38, all of the high-pressure ink generated in the bypass pipe 32P is directed to the ink discharge unit 22. Therefore, breakage of the atmospheric pressure detection membrane 7 defining the second chamber 42 is prevented.

Fig. 9(B) is a diagram showing a state in which the decompression mode is executed. In the pressure reducing mode, the pump 9 is driven in reverse. The clamp 35V is closed. When the pump 9 is driven in reverse, the ink discharge portion 22 and the second chamber 42 are depressurized through the downstream pipe 34 and the bypass pipe 32P. The ink ejecting unit 22 and the second chamber 42 are set to a predetermined negative pressure by the decompression mode, that is, a negative pressure at which ink droplets do not leak and drip from the ink ejecting unit 22 even when the water head difference is supplied. Further, if the ink ejecting section 22 is set to an excessive negative pressure, ink ejection may be inhibited by driving of a piezoelectric element or the like in the ink ejecting section 22. Therefore, the ink ejecting section 22 and the second chamber 42 are preferably set to a weak negative pressure of about-0.2 to-0.7 kPa, for example.

[ integral Structure of liquid supply Unit ]

Next, the configuration of the liquid supply unit 3 according to the present embodiment that can execute each mode of the liquid supply system described above will be described in detail. Fig. 10(a) and (B) are perspective views of the liquid supply unit 3, fig. 10(a) is a perspective view seen from the first chamber 41 side, and fig. 10(B) is a perspective view seen from the second chamber 42 side. Fig. 11 is a perspective view of the liquid supply unit 3 showing a state where the closing film 7A on the first chamber 41 side is removed, and fig. 12(a) to (C) are perspective views of the liquid supply unit 3 showing a state where the atmospheric pressure detection film 7 on the second chamber 42 side is removed. Fig. 13 is an exploded perspective view of the liquid supply unit 3.

As explained preliminarily with reference to fig. 7 to 9(B), the liquid supply unit 3 includes a main body 30 having a tank portion 31 and a pump portion 32, an upstream pipe 33, a downstream pipe 34, a return pipe 35, a bypass pipe 32P, an exhaust mechanism portion 37, a backflow prevention mechanism portion 38, a pressing member 5, an opening/closing valve 6, and an atmospheric pressure detection membrane 7. Further, the liquid supply unit 3 includes: a monitor tube 36 for monitoring the ink level of the second chamber 42; and a closing film 7A constituting a part of the wall surface defining the first chamber 41.

The main body 30 includes a base substrate 300 (fig. 11) formed of a flat plate extending in the front-rear direction. The front side of the base 300 is a tank portion substrate 310 (wall portion) serving as a substrate of the tank portion 31, and the rear side is a pump portion casing 320 having a casing structure in the pump portion 32. The first chamber 41 is disposed on the left side of the tank substrate 310, and the second chamber 42 is disposed on the right side. The first chamber 41 and the second chamber 42 are spaces in which ink can be stored. A communication port 43 for communicating the first chamber 41 and the second chamber 42 is perforated in the tank portion substrate 310. The opening/closing valve 6 is disposed in the communication port 43.

As shown in fig. 11, the first chamber 41 is formed by a space having a narrow width and having a U-shape when viewed from the left side. The first chamber 41 is defined by a first defining wall 411 that protrudes leftward from the tank base plate 310. The first defining wall 411 is formed of a pair of wall pieces facing each other with a predetermined distance therebetween. The inflow portion 412, which is the upstream end of the first chamber 41, communicates with a filter chamber 44 described later. The ink supplied from the upstream pipe 33 to the tank portion 31 flows from the inflow portion 412 into the first chamber 41 via the filter chamber 44.

The first chamber 41 extends in the horizontal direction from the inflow portion 412 toward the front, and then is curved downward. A bypass communication chamber 413 and a return communication chamber 414 are connected to the downstream end of the first chamber 41 in a Y-branch shape. The bypass communication chamber 413 is a region for connecting the first chamber 41 and the bypass upstream pipe BP 1. An upstream end of the bypass upstream pipe BP1 is connected to a wall portion defining the vicinity of the lower end of the bypass communication chamber 413. The return communication chamber 414 is a region for connecting the first chamber 41 and the return pipe 35. A downstream end 352 of the return pipe 35 is connected to a wall portion defining the vicinity of the front end of the return communication chamber 414. In fig. 7 and 8, the return communication chamber 414 is used as a part of the return pipe 35.

A lower monitor communication chamber 415 is disposed above the return communication chamber 414, and an upper monitor communication chamber 416 is disposed above the horizontal portion of the first chamber 41. An upstream end 361 of the monitor tube 36 communicates with the lower monitor communicating chamber 415, and a downstream tube 362 of the monitor tube 36 communicates with the upper monitor communicating chamber 416. Referring to fig. 12, a lower communication hole 41A and an upper communication hole 41B arranged above the lower communication hole 41A are perforated in the tank portion base plate 310. The lower monitor communication chamber 415 communicates with the second chamber 42 through the lower communication hole 41A, and the upper monitor communication chamber 416 communicates with the second chamber 42 through the upper communication hole 41B. That is, the monitor tube 36 communicates with the upper end side and the lower end side of the second chamber 42, and the ink level in the monitor tube 36 and the ink level in the second chamber 42 are interlocked.

In the present embodiment, the monitor tube 36 is formed of a transparent resin tube. Therefore, the user can know the ink level in the second chamber 42 by visually checking the monitor tube 36. In the present embodiment, as shown in fig. 4, a plurality of liquid supply units 3 are arranged in parallel in the left-right direction on the holder 2. Therefore, even if a transparent film is used as the atmospheric pressure detection film 7 located on the right side surface, the ink level in the second chamber 42 cannot be visually confirmed except for the rightmost liquid supply unit 3. However, in the present embodiment, the monitor tube 36 is erected on the front side of the liquid supply unit 3. Therefore, the user can know the ink level in each second chamber 42 by visually checking the monitor tube 36 of each liquid supply unit 3 from the front side of the holder 2.

A spring seat 417 formed of a cylindrical hollow cavity is provided so as to protrude leftward in the vicinity of the center of the first chamber 41 in the vertical direction. The spring seat 417 is a cavity that accommodates an urging spring 45 described later, and opens to the second chamber 42 side. The first chamber 41 is set to substantially a half turn around the outer peripheral wall of the spring seat 417. A compartment 418 is provided behind the spring seat 417. The partition 418 is provided to reduce the volume of the first chamber 41 as much as possible. If the volume of the first chamber 41 becomes larger, the amount of ink stored becomes larger. When the holder 2 moves, a swinging force is applied to the liquid supply unit 3, and if the weight of the ink is large, the atmospheric pressure detection film 7 and the sealing film 7A may be peeled or damaged by an inertial force. In the case where such a possibility does not occur, the partition chamber 418 may be omitted, and the first chamber 41 may be set to surround the spring seat 417, for example.

The communication port 43 is disposed in the first chamber 41 at a position above the spring seat 417. A cylindrical protruding portion 419 protrudes leftward from the can base plate 310 in the first chamber 41. The communication port 43 is provided so as to penetrate the protruding portion 419 in the left-right direction. The first chamber 41 is a chamber to which a pressure P ═ ρ gh based on a water head difference is applied in addition to atmospheric pressure without being subjected to a pressure reduction process or the like. When ink flows into the first chamber 41 from the inlet 412, ink storage starts in order from the bypass communication chamber 413 and the return communication chamber 414. If the liquid level of the ink exceeds the communication port 43, the ink can be supplied to the second chamber 42 through the communication port 43. When the pump 9 is operated, the ink stored in the first chamber 41 is sucked through the bypass upstream pipe BP1, and the ink having a high pressure is supplied to the head unit 21 through the bypass downstream pipe BP2 and the downstream pipe 34.

Referring mainly to fig. 12(a) to (C) and fig. 13, the second chamber 42 has a circular shape when viewed from the right side in plan. The pressing member 5 and the opening/closing valve 6, an urging spring 45 described later, and a rod member 46 are assembled to the second chamber 42. Fig. 12(a) shows a state in which these four members are assembled in the second chamber 42, fig. 12(B) shows a state in which the pressing member 5 is removed, and fig. 12 (C) shows a state in which the opening/closing valve 6 and the biasing spring 45 are removed.

The second chamber 42 is defined by a second defining wall 421 provided to protrude rightward from the tank portion base plate 310. The second defining wall 421 is a wall having a cylindrical shape. The second chamber 42 and the first chamber 41 located on the left side are in a positional relationship facing each other with the tank substrate 310 interposed therebetween. The spring seat 417 is recessed in the tank portion base plate 310 at the center of the region surrounded by the cylindrical second defining wall 421, that is, at a position concentric with the second defining wall 421. The biasing spring 45 is housed in a recess of the spring seat 417. The communication port 43 is disposed above the spring seat 417 on a vertical line passing through a center point of the spring seat 417.

A rod member 46 for exhausting the second chamber 42 is disposed on the upper end 422 side of the second chamber 42. At the lower end 423 (the lowermost portion of the second chamber 42), a supply hole 42H is bored in the second defining wall 421. The upstream end 341 of the downstream pipe 34 communicates with the supply hole 42H through the backflow prevention mechanism 38. The second chamber 42, the backflow prevention mechanism 38, and the downstream pipe 34 are arranged in the vertical direction corresponding to the supply hole 42H such that: the backflow prevention mechanism 38 is located below the second chamber 42, and a junction a between the downstream end of the downstream pipe 34 and the downstream end of the bypass pipe 32P (bypass downstream pipe BP2) is located below the backflow prevention mechanism 38. The ink stored in the second chamber 42 is supplied to the downstream pipe 34 through the supply hole 42H and the backflow prevention mechanism 38 so as to be sucked by the ink discharge portion 22. The backflow prevention mechanism 38 will be described in detail later.

Near the lower end 423, a pair of front and rear support plates 424 are provided to protrude rightward from the tank base plate 310. The pair of support plates 424 each include a pivot support portion 425 that pivotally supports a pressing member 5 described later. The lower communication hole 41A is inserted through the tank base plate 310 at a position adjacent to the front of the front support plate 424. The upper communication hole 41B penetrates the tank base plate 310 near the upper end 422.

A projection 426 and a holding frame 427 are provided to project upward from the upper end 422 of the second chamber 42. The protruding portion 426 is a cylindrical body extending vertically upward, and includes a protruding hole 42A (fig. 22A) therein, which is an opening for allowing the second chamber 42 to communicate with the atmosphere. The holding frame 427 is formed of a pair of frame pieces arranged to sandwich the protruding portion 426 in the front-rear direction. The holding frames 427 have locking claws 428 bent in directions facing each other at the upper ends thereof. The protrusion 426 and the holding frame 427 constitute a part of the exhaust mechanism 37, and a lever member 46 (fig. 20 a) described later is assembled.

Referring to fig. 11, a filter chamber 44 is disposed on the upstream side of the first chamber 41 in the ink supply direction. The filter chamber 44 constitutes a path for supplying ink from the ink cartridge IC to the first chamber 41 together with the upstream pipe 33. The filter chamber 44 has a rectangular cross-sectional shape with an inner wall surface 441 defining a space extending in a square cylindrical shape in the ink supply direction. As will be described later (fig. 19 a), the filter chamber 44 is a space for accommodating the filter member 442 for removing foreign substances in the ink, a holding member 443 of the filter member 442, a coil spring 446 for fixing the filter member 442, and the like. An ink inlet 44H (fig. 19B) is formed through the top wall of the filter chamber 44. An inlet port 447 (fig. 25) formed by receiving a plug is provided upright on the top wall corresponding to the inlet 44H. A downstream end 332 to which an upstream pipe 33 is connected is inserted into the inflow port 447.

Referring to fig. 10(a) and (B) and fig. 13, the left side opening of the first chamber 41 is closed by a closing film 7A made of resin. The sealing film 7A has an outer shape capable of covering and hiding not only the first chamber 41 but also the bypass communication chamber 413, the return communication chamber 414, the lower monitor communication chamber 415, the upper monitor communication chamber 416, and the filter chamber 44. The closing film 7A closes the opening of each chamber by welding or adhering the peripheral edge portion of the closing film 7A to the opening end surfaces of the first defining wall 411 and the other walls.

The right-side opening of the second chamber 42 is closed by an atmospheric pressure detection membrane 7 made of a flexible resin membrane member. The atmospheric pressure detection membrane 7 has a circular outer shape that matches the wall shape of the second defining wall 421 of the second chamber 42 when viewed from the right side in plan. The peripheral edge portion of the atmospheric pressure detection membrane 7 is welded or bonded to the opening end face of the second defining wall 421, and closes the opening of the second chamber 42. In addition, the atmospheric pressure detection film 7 is welded or bonded in a state where no tension is particularly applied.

The pump portion 32 is disposed adjacent to the obliquely rearward and downward direction of the tank portion 31, and includes a cam shaft insertion hole 322 through which a pump chamber 321 that houses the pump 9 and a cam shaft 93 (fig. 4) that pivotally supports an eccentric cam 91 (fig. 25) of the pump 9 are inserted. The pump chamber 321 is a cylindrical chamber disposed in the pump section case 320. The cam shaft insertion hole 322 is a protruding hole provided at a position concentric with the pump chamber 321. The opening on the right side of the pump chamber 321 is closed by a pump cover 323 (fig. 10 (B)). Two positioning pins 391 project from the rear side of the pump section casing 320, and a rib 392 projects from the lower side. These positioning pins 391 and ribs 392 function as positioning members when the liquid supply unit 3 is mounted on the holder 2.

The liquid supply unit 3 of the present embodiment is integrally formed by a tank portion 31 and a pump portion 32. That is, the tank portion substrate 310, which is a substrate of the tank portion 31, and the pump portion casing 320 including the pump chamber 321 are integrated, and the pump 9 for pressure cleaning is mounted on the liquid supply unit 3 itself. Accordingly, the device structure of the stand 2 can be made compact and simplified.

[ detailed Structure of negative pressure supply mechanism ]

Next, a negative pressure supply mechanism for supplying ink from the first chamber 41 to the second chamber 42 in response to a decrease in ink in the second chamber 42 will be described in detail. The negative pressure supply mechanism includes the pressing member 5, the opening/closing valve 6, and the atmospheric pressure detection membrane 7, which have been described above with reference to fig. 7 in brief, and further includes a biasing spring 45 (biasing member). The opening/closing valve 6 is disposed in the communication port 43, and changes its position between a closed position for closing the communication port 43 and an open position for opening the communication port 43. The biasing spring 45 applies a force to the opening/closing valve 6 in the direction of the closed position. The urging member 5 can urge the opening/closing valve 6 in the direction of the open posture. The atmospheric pressure detection membrane 7 is displaced based on the negative pressure generated with the decrease in the ink in the second chamber 42, and transmits the displacement force to the pressing member 5.

< push Member >

Fig. 14(a) and (B) are perspective views of the pressing member 5 with different directions of view, and show the opening/closing valve 6. The pushing member 5 is a member rotatably disposed in the second chamber 42. The pressing member 5 includes: a circular plate portion 51 formed of a circular flat plate; a pair of arm portions 52 extending downward from the lower end side 5C of the disc portion 51; a fulcrum portion 53 provided at an extended distal end portion (lower end portion) of each arm portion 52; a pair of link projections 54 (pressing portions) arranged on the upper end side 5D of the disk portion 51; and a receiving slope 55 interfering with the lever member 46. The pair of fulcrum portions 53 are pivotally supported by pivot supporting portions 425 (fig. 12) of the pair of support plates 424 disposed in the second chamber 42. Accordingly, the disk portion 51 is rotatable about the axis of the fulcrum portion 53.

The disc portion 51 is a disc having a diameter of about 1/2 degrees with respect to the inner diameter of the cylindrical second defining wall 421 defining the second chamber 42. The second defining wall 421 and the disc portion 51 in a state of being pivotally supported by the pivotal support portion 425 are substantially concentric in arrangement relationship. The circular plate portion 51 includes: a first surface 51A facing the atmospheric pressure detection film 7; and a second surface 51B facing the opening/closing valve 6 (facing the can substrate 310). A spring fitting protrusion 511 is provided at the radial center of the disk portion 51 so as to protrude from the second surface 51B. The right end of the biasing spring 45 formed of a coil spring is fitted to the second surface 51B side of the spring fitting projection 511. Further, the region of the spring fitting protrusion 511 on the first surface 51A side is a columnar recess.

The circular plate portion 51 includes: a pressure receiving section 5A that receives a displacement force from the atmospheric pressure detection membrane 7; and a biased portion 5B biased by a biasing spring 45. The pressure receiving portion 5A is set at a predetermined position on the first surface 51A of the disc portion 51. In the present embodiment, the pressure receiving portion 5A is a region of the first surface 51A at the peripheral edge of the spring fitting protrusion 511. The biased portion 5B is a region of the spring fitting protrusion 511 in which the biasing spring 45 on the second surface 51B side is fitted. That is, the urged portion 5B is set at a position corresponding to the pressure receiving portion 5A.

When the pressure receiving portion 5A does not receive a displacement force from the atmospheric pressure detection membrane 7, the disk portion 51 is in a state of being nearly upright. However, the right end of the biasing spring 45 abuts against the biased portion 5B, and the first surface 51A is in contact with the inner surface of the atmospheric pressure detection membrane 7 by the biasing force thereof. On the other hand, if the pressure receiving portion 5A receives a displacement force equal to or greater than the biasing force of the biasing spring 45 from the atmospheric pressure detection film 7, the disc portion 51 pivots leftward about the axis of the fulcrum portion 53, and becomes inclined leftward from the upright state.

The pair of arm portions 52 are disposed apart from each other in the front-rear direction on the lower end side 5C of the disk portion 51. The upper end portions 521 of the pair of arm portions 52 extend upward from the lower end side 5C of the disc portion 51 and are located below the respective side portions of the spring fitting protrusion 511. The distal end portions 522 of the pair of arm portions 52 extend linearly downward from the lower end side 5C. Each fulcrum portion 53 is provided to protrude from the distal end portion 522 in the front-rear direction. Specifically, the fulcrum portions 53 protrude forward from the front side surface of the front distal end portion 522, the fulcrum portions 53 protrude rearward from the rear side surface of the rear distal end portion 522, and the pair of fulcrum portions 53 protrude in a direction away from each other. The fulcrum portion 53 is fitted into the pivot supporting portion 425 of the supporting plate 424. The provision of the fulcrum portion 53 at the distal end portion 522 of the arm portion 52 contributes to an increase in the amplitude of oscillation of the upper end side 5D of the disk portion 51 when the pressing member 5 rotates about the fulcrum portion 53.

The pair of fulcrum portions 53 are arranged on a rotation shaft 5AX extending in the front-rear direction. The front fulcrum 53 and the rear fulcrum 53 are disposed at a predetermined distance D. That is, the pair of supporting portions 53 are disposed apart from each other across a portion corresponding to the central region of the disk portion 51 in the planar direction. The distance D may be set to a dimension of about 40% to 90% of the diameter of the disc portion 51, for example. Accordingly, the pivot formed by the pair of pivot portions 53 is a wide pivot separated from and sandwiching the central region of the disc portion 51. Therefore, the disk portion 51 that rotates around the rotation fulcrum is less likely to twist around an axis perpendicular to the rotation axis 5 AX. Therefore, the rotational operation of the disk portion 51 can be stabilized.

The pair of link protrusions 54 protrude leftward from the second surface 51B in the vicinity of the upper end side 5D of the disk portion 51. Specifically, the disk portion 51 is provided with a cutout portion 512 extending radially inward with the upper end side 5D as an opening edge, and link protrusions 54 formed of rectangular flat plates are provided so as to stand from front and rear side end edges of a space facing the cutout portion 512. Each link protrusion 54 has a link hole 541. The link hole 541 is used for link coupling of the pushing member 5 and the opening/closing valve 6. The opening and closing operation of the opening and closing valve 6 is linked with the rotation operation of the pressing member 5 by the link connection.

In other words, the link projection 54 serves as a pressing portion that presses the opening/closing valve 6 to move in the left-right direction in response to the rotational operation of the pressing member 5 that rotates about the axis of the fulcrum portion 53. The pair of link projections 54 are disposed on the upper end side 5D apart from the pair of fulcrum portions 53 disposed on the lower end side 5C by a predetermined distance. That is, the link projection 54 serving as the pressing portion is disposed at a position opposite to the disk portion 51 with respect to the fulcrum portion 53 serving as a rotation fulcrum. Therefore, the amount of movement of the link projection 54 when the pressing member 5 rotates and the amount of movement of the opening/closing valve 6 linked to the link projection 54 can be increased.

The link projection 54 (operating point) is disposed at a position farther from the fulcrum 53 than the pressure receiving portion 5A and the urged portion 5B with respect to the fulcrum 53 with respect to the relationship between the pressure receiving portion 5A or the urged portion 5B (force point) and the fulcrum 53 (fulcrum). In other words, the link projection 54 is disposed on the upper end side 5D of the disc portion 51 so as to face the fulcrum portion 53 with the pressure receiving portion 5A and the urged portion 5B interposed therebetween. With such an arrangement, the moving force received by the pressure receiving portion 5A or the urged portion 5B can be applied to the link projection 54 by increasing the amount corresponding to the distance therebetween.

< opening and closing valve >

Next, the opening/closing valve 6 will be described. The opening/closing valve 6 is disposed in a communication port 43 that communicates the first chamber 41 and the second chamber 42. The opening/closing valve 6 moves in the left-right direction in the communication port 43 in accordance with the rotation of the pressing member 5 around the fulcrum 53, thereby opening and closing the communication port 43. The opening/closing valve 6 is linked to the link projection 54 of the disk portion 51 by following the rotational operation.

Fig. 15(a) is a perspective view of the opening/closing valve 6, and fig. 15(B) is an exploded perspective view of the opening/closing valve 6. Fig. 16(a) is a cross-sectional view taken along line XVI-XVI in fig. 10(a), and fig. 16(B) is an enlarged view of portion a1 in fig. 16 (a). The opening/closing valve 6 is formed by an assembly of a valve support 61 and an umbrella valve 66 held by the valve support 61. The communication port 43 is a cylindrical hole penetrating the can base plate 310 and the protruding portion 419, and has a large diameter portion 43A, a small diameter portion 43B having an inner diameter smaller than that of the large diameter portion 43A, and a stepped portion 43C based on a difference in diameter between the two portions.

The valve support 61 is a member having a semi-cylindrical shape and having a first end 611 located on the first chamber 41 side (left side) and a second end 612 located on the second chamber 42 side (right side) in a state of being assembled to the communication port 43. The valve support 61 includes: a cylindrical portion 62 on the first end 611 side; the flat plate portion 63 on the second end portion 612 side; an intermediate portion 64 located between the cylindrical portion 62 and the flat plate portion 63; and a link pin 65 disposed on the flat plate portion 63. The umbrella valve 66 is held on the first end 611 side of the valve support 61.

The cylindrical portion 62 is a cylindrical portion having the largest outer diameter of the valve support 61. The cylindrical portion 62 includes: a guide surface 62S as an outer peripheral surface of the cylindrical portion 62; a flow path slit 621 formed by cutting a part of the cylindrical portion 62 in the circumferential direction; and a retaining groove 622 recessed annularly on the inner peripheral side of the cylinder portion 62. The cylindrical portion 62 is accommodated in the large diameter portion 43A of the communication port 43, and when the opening/closing valve 6 moves in the left-right direction, the guide surface 62S is guided by the inner surface of the large diameter portion 43A. The flow path slit 621 is a flow path through which ink flows when the on-off valve 6 is in the open position. The retaining groove 622 is a groove for locking the locking ball 663 of the umbrella valve 66.

The intermediate portion 64 is a cylindrical portion having an outer diameter smaller than that of the cylindrical portion 62. The intermediate portion 64 includes: an opening 641 serving as an opening portion connected to the flow path slit 621; and a pin receiving portion 642 that receives the pin portion 662 of the umbrella valve 66. The intermediate portion 64 is accommodated in the small diameter portion 43B of the communication port 43, and the outer peripheral surface thereof is also guided by the inner surface of the small diameter portion 43B. An annular contact portion 62A formed by a step due to the difference in outer diameter between the cylindrical portion 62 and the intermediate portion 64 is present at the boundary portion therebetween. The annular contact portion 62A faces and contacts the stepped portion 43C of the communication port 43.

The flat plate portion 63 projects rightward from the communication port 43 in a state where the opening/closing valve 6 is assembled to the communication port 43. The flat plate portion 63 has a pair of front and rear flat surfaces extending in the left-right direction. The link pins 65 are provided to protrude in the vertical direction from the pair of flat surfaces. As shown in fig. 14(B), the link pin 65 is fitted into a link hole 541 provided in the link projection 54 of the pressing member 5. By this fitting, the pressing member 5 and the opening/closing valve 6 are coupled by a link, and the rotational motion of the pressing member 5 can be converted into the linear motion of the opening/closing valve 6.

The umbrella valve 66 is a rubber article, and includes an umbrella portion 661, a pin portion 662 extending rightward from the umbrella portion 661, and a locking ball portion 663 integrally provided to the pin portion 662. The umbrella portion 661 has an umbrella diameter larger than the inner diameter of the large diameter portion 43A of the communication port 43. The peripheral edge of the inner side (right side) of the umbrella portion 661 is a sealing surface 67. The sealing surface 67 can set the communication port 43 in a closed state (closed posture) by abutting against a sealing wall surface 43S which is a wall surface around the communication port 43 and which is a protruding end surface of the protruding portion 419. On the other hand, if the seal surface 67 is separated from the seal wall surface 43S, the closed state is released (open posture). When a predetermined pressure is applied to the right side of the umbrella part 661, the umbrella shape is reversed (fig. 29(a) and (B)).

The pin portion 662 is a rod-like portion extending in the left-right direction, and is a portion serving as a support of the umbrella portion 661. The pin portion 662 enters the cylindrical portion 62 of the valve support 61 and the pin receiving portion 642 of the intermediate portion 64. That is, the umbrella portion 661 abuts against the first end portion 611 of the valve support 61, and the pin portion 662 can be fitted into the inner tube portion of the valve support 61. The locking ball portion 663 is formed by the left end portion of the pin portion 662 being spherically expanded and fitted into the retaining groove 622. The umbrella valve 66 is held by the valve support 61 in a state in which the movement in the left-right direction is restricted by the locking ball 663 being fitted into the holding groove 622. That is, the umbrella valve 66 moves in the left-right direction integrally with the valve support 61.

< urging spring >

The biasing spring 45 is a coil spring that is interposed between the second surface 51B of the disc portion 51 and the tank portion substrate 310 and supports (biases) the second surface 51B. Specifically, as shown in fig. 16(B), the biasing spring 45 is fitted to the spring fitting projection 511 of the circular plate portion 51 at the right end side thereof, and is accommodated in the spring seat 417 recessed in the tank portion base plate 310 at the left end side thereof. When the pressure receiving portion 5A of the disk portion 51 receives a leftward displacement force against the rightward biasing force of the biasing spring 45, the disk portion 51 pivots leftward about the axis of the fulcrum portion 53. The disk portion 51 maintains an upright posture by the biasing force without receiving the displacement force.

< action of opening and closing valve >

Next, the opening and closing operation of the opening and closing valve 6 will be described. Fig. 16 shows a state in which the on-off valve 6 is in the closed position. This state is a state in which the atmospheric pressure detection membrane 7 does not generate a displacement force to such an extent that the pressing member 5 (disk portion 51) is rotated, that is, a state in which the total of the spring pressure (urging force) of the urging spring 45 and the internal pressure of the second chamber 42 is greater than the atmospheric pressure. Although the second chamber 42 is at a negative pressure, the biasing spring 45 applies a force to the biased portion 5B of the disk portion 51 in the rightward direction with a force larger than the displacement force of the atmospheric pressure detection film 7 generated by the negative pressure. Therefore, the circular plate 51 maintains the upright posture without rotating about the axis of the fulcrum 53.

At this time, the opening/closing valve 6 linked to the pressing member 5 at the link projection 54 is in the closed position on the rightmost side. That is, the valve support 61 is pulled rightward by the link projection 54 due to the biasing force of the biasing spring 45. Therefore, the annular contact portion 62A of the valve support 61 is in contact with the stepped portion 43C of the communication port 43, and the sealing surface 67 of the umbrella valve 66 is in contact with the sealing wall surface 43S. Thereby, the communication port 43 is closed by the umbrella valve 66. The biasing spring 45 indirectly applies a force in the direction toward the closed position to the opening/closing valve 6 by applying a force in the right direction to the disk portion 51.

Fig. 17(a) is a cross-sectional view corresponding to fig. 16(a) and showing a state in which the opening/closing valve 6 is in an open position, and fig. 17(B) is an enlarged view of a portion a2 of fig. 17 (a). If the ink ejecting section 22 continues the ink droplet ejecting operation from the state shown in fig. 16(B), the negative pressure level of the second chamber 42, which is a closed space, gradually increases as the ink decreases. After that, if the second chamber 42 reaches a negative pressure exceeding a predetermined threshold value, the atmospheric pressure detection membrane 7 applies a pressing force against the urging force of the urging spring 45 to the pressure receiving portion 5A of the disc portion 51. That is, the total of the spring pressure of the biasing spring 45 and the internal pressure of the second chamber 42 is lower than the atmospheric pressure.

At this time, the disk portion 51 rotates leftward about the axis of the supporting point 53 against the biasing force of the biasing spring 45. By this rotation, the link projection 54 generates a pressing force PF that causes the opening/closing valve 6 to face leftward, and the posture of the opening/closing valve 6 is changed to the open posture. That is, the urging force is transmitted from the link hole 541 of the link protrusion 54 to the link pin 65 of the valve support 61, the guide surface 62S is guided by the inner surface of the communication port 43, and the valve support 61 moves linearly in the left direction. With this movement, the umbrella valve 66 also moves leftward, and the sealing surface 67 thereof is separated from the sealing wall surface 43S. That is, the gap G is formed between the seal surface 67 and the seal wall surface 43S. Therefore, the closing of the communication port 43 by the umbrella valve 66 is released.

When the on-off valve 6 is in the open position, ink flows from the first chamber 41 into the second chamber 42 due to the pressure difference between the first chamber 41 and the second chamber 42 in which the negative pressure level is increased, as indicated by the arrow F in fig. 17 (B). Specifically, the ink flows into the second chamber 42 through a flow path formed by a gap G between the seal surface 67 of the umbrella valve 66 and the seal wall surface 43S, the flow path slit 621 provided in the cylinder portion 62 of the valve support 61, and the opening 641 provided in the intermediate portion 64.

If the ink flowing into the second chamber 42 increases, the degree of negative pressure of the second chamber 42 gradually decreases. After that, if the sum of the spring pressure of the biasing spring 45 and the internal pressure of the second chamber 42 is larger than the atmospheric pressure, the disk portion 51 is pushed back rightward by the biasing force of the biasing spring 45. That is, if the second chamber 42 reaches a negative pressure lower than the predetermined threshold value, the disk portion 51 is pressed by the biasing force of the biasing spring 45 and rotates rightward around the axis of the fulcrum portion 53. Accordingly. The opening/closing valve 6 is also pulled by the link projection 54 to move linearly rightward. Then, the annular contact portion 62A of the valve support 61 contacts the stepped portion 43C of the communication port 43, and the seal surface 67 of the umbrella valve 66 contacts the seal wall surface 43S. Therefore, the opening/closing valve 6 is returned to the closed position.

< effect of negative pressure supply mechanism >

The operational effects of the negative pressure supply mechanism of the present embodiment having the above-described configuration will be described with reference to the schematic diagrams of fig. 18(a) and (B). Fig. 18(a) shows a state in which the pressing member 5 (the circular plate portion 51) is in a hanging posture and the opening/closing valve 6 is in a closed posture, and fig. 18(B) shows a state in which the pressing member 5 is in an inclined posture by rotation and the opening/closing valve 6 is in an open posture.

First, the pressing member 5 has a rotation fulcrum of the fulcrum portion 53 and is pivotally supported by the support plate 425 disposed in the second chamber 42. Therefore, if the pressure receiving portion 5A receives the displacement force of the atmospheric pressure detection membrane 7, the pressing member 5 rotates about the axis of the fulcrum portion 53. That is, an unstable moving force of the displacement of the atmospheric pressure detection membrane 7 can be converted into a stable moving force of the rotation about the axis of the fulcrum portion 53. Therefore, the displacement force of the atmospheric pressure detection membrane 7 can be efficiently transmitted to the opening/closing valve 6 through the link protrusion 54 (pressing portion). For example, when the pressing member of the opening/closing valve 6 is stuck to the atmospheric pressure detection membrane 7 or the like, the operation thereof becomes unstable, and the transmission of the pressing force to the opening/closing valve 6 becomes unstable. However, according to the present embodiment, since the pressing member 5 generates a stable pressing force, the on-off valve 6 can be changed in posture between the closed posture and the open posture at a desired timing, and ink can be stably supplied to the head unit 21.

Further, the fulcrum portion 53 is disposed on the lower end side 5C of the pressing member 5, and the link projection 54 is disposed on the upper end side 5D of the pressing member 5 apart from the fulcrum portion 53 by a predetermined distance. That is, as shown in fig. 18(a), when the pivot point of the pivot point portion 53 is set to the pivot point P1 and the link protrusion 54 that inputs the moving force to the opening/closing valve 6 is set to the operating point P2, the operating point P2 is disposed at the opposite position of the pivot point P1 with respect to the pressing member 5. A force point P3 at which the pushing member 5 is rotated is the arrangement position of the pressure receiving portion 5A and the biased portion 5B in the present embodiment, and the force point P3 is located between the fulcrum P1 and the operating point P2.

Therefore, the amount of movement of the link projection 54 when the pressing member 5 rotates can be increased, and the amount of linear movement of the opening/closing valve 6 in the left-right direction can be increased. As shown in fig. 18B, when the pressing force of the atmospheric pressure detection membrane 7 is applied to the working point P2 (the pressure receiving portion 5A), the pressing member 5 pivots by an angle θ 1 about the axis of the fulcrum portion 53. At this time, the actual movement amount of the pusher 5 at the position of the pressure receiving portion 5A is d1, but the movement amount at the position of the link protrusion 54 (link pin 65) becomes a movement amount d2 that is larger than d1 by an amount corresponding to the difference in distance between the point of action P2 and the point of force P3 with respect to the fulcrum P1.

As described with reference to fig. 16(a) to 17(B), the opening/closing valve 6 is not a member that opens and closes the communication port 43 by a pressing force, but a member that opens and closes the communication port 43 by moving in the left-right direction in the communication port 43. Further, as the opening/closing valve 6 moves leftward, the gap G also increases, and the ink inflow resistance decreases. When the ink in the second chamber 42 is rapidly consumed, a large pressing force is applied from the atmospheric pressure detection membrane 7, and therefore the moving amount d1 is also relatively large. The opening/closing valve 6 can be moved leftward by the movement amount d2 obtained by multiplying the movement amount d 1. Therefore, when ink is rapidly consumed, a relatively large amount of ink can be caused to flow into the second chamber 42 by moving the opening/closing valve 6 relatively large.

In contrast, when the ink in the second chamber 42 is gradually consumed, the pressing force applied from the atmospheric pressure detection membrane 7 becomes small, and the moving amount d1 becomes small. Even with such a small movement amount d1, the position of the link projection 54 is enlarged to the movement amount d2, and the on-off valve 6 can be moved leftward accordingly. Therefore, even when ink is consumed gently, the open/close valve 6 can be moved at a proper timing with good sensitivity. This ensures stable supply of ink from the liquid supply unit 3 to the head unit 21 both when a large amount of ink is discharged from the head unit 21 and when a small amount of ink is discharged.

Further, as another advantage, there is an advantage that the opening/closing valve 6 is linked to the pressing member 5. Specifically, the link pin 65 disposed near the right end of the opening/closing valve 6 and the link hole 541 of the link protrusion 54 form a link coupling. The biasing spring 45 biases the opening/closing valve 6 in the direction toward the closed position by pressing the biased portion 5B of the disc portion 51. Therefore, the pressing member 5 (the disc portion 51) rotates around the axis of the fulcrum portion 53, and is inclined toward the left by the rotation angle θ 1 as shown in fig. 18 (B). However, the opening/closing valve 6 does not tilt following the tilting operation of the disc portion 51 due to the link connection. That is, the opening/closing valve 6 rotates around the link pin 65 by the rotation angle θ 2 corresponding to the rotation angle θ 1, and the horizontal posture can be maintained. Therefore, the opening/closing valve 6 can be linearly moved in the left-right direction in the communication port 43, and the opening/closing valve 6 can be stably operated between the closed posture and the open posture.

[ detailed Structure of Filter Chamber ]

Next, the structure of the filter chamber 44 is described in detail. Fig. 19(a) is an exploded perspective view of the filter chamber 44, and fig. 19(B) is a front-rear sectional view of the filter chamber 44. As described above, the filter chamber 44 has the inner wall surface 441 defining a square tubular space, and the filter member 442, the holding member 443, and the coil spring 446 are accommodated in the space.

The filter member 442 is a filter member that removes foreign substances contained in the ink. The foreign matter here is, for example, hair dust, an aggregate of ink liquid, or the like. In the present embodiment, ink flows from the first chamber 41 into the second chamber 42 through the communication port 43 in which the on-off valve 6 is disposed. Then, the communication port 43 is closed by the opening/closing valve 6, and the negative pressure operation of the pressing member 5 in the second chamber 42 is realized. If ink containing foreign matter is supplied to such an environment, the negative pressure action may be hindered. In particular, if foreign matter bites into the opening/closing valve 6, the opening/closing valve 6 is prevented from moving in the left-right direction, and the second chamber 42 cannot maintain the negative pressure. Further, if the foreign matter enters the head unit 21 on the downstream side of the second chamber 42, it is difficult to remove the foreign matter, and the ink ejection operation is hindered. The filter member 442 is disposed to prevent such a malfunction due to the mixing of foreign matter.

As the filter 442, various filter members can be used as long as the filter member can capture the foreign matter and pass the ink liquid. For example, a woven fabric, a nonwoven fabric filter, a sponge filter, a mesh filter, or the like can be used as the filter member 442. In the present embodiment, the filter member 442 formed of a sheet member having a rectangular shape in a plan view is used. The size of the filter member 442 is set to be substantially the same as the cross-sectional size of the inner wall surface 441 of the filter chamber 44 in the left-right direction.

The filter chamber 44 includes an upstream end 441A on the upstream side and a downstream end 441B on the downstream side in the ink supply direction. An inflow port 44H is formed through a top wall of the filter chamber 44 on the upstream end 441A side. An inflow port 447 (fig. 25) is provided upright immediately above the inflow port 44H, and the downstream end 332 of the upstream pipe 33 is inserted into and connected to the inflow port 447. Therefore, the ink supplied from the ink cartridge IC flows from the inflow port 44H into the upstream end 441A side of the filter chamber 44. The downstream end 441B communicates with the inflow portion 412, which is the upstream end of the first chamber 41.

The filter member 442 is disposed near the downstream end 441B in the present embodiment. As described above, since the foreign matter is caught in the opening/closing valve 6, the filter member 442 may be disposed on the upstream side of the opening/closing valve 6. That is, the filter member 442 may be disposed at any position of the ink supply path between the ink cartridge IC and the first chamber 41 or at a position upstream of the opening/closing valve 6 in the first chamber 41. According to this configuration, foreign matter is caught by the filter member 442 before reaching the communication port 43 or the second chamber 42. Therefore, it is possible to prevent a problem that foreign matter is caught in the opening/closing valve 6 or that foreign matter reaches the head unit 21 from the second chamber 42, and it is possible to prevent a malfunction of the liquid supply unit 3 due to the mixing of foreign matter.

The holding structure of the filter element 442 is explained. As shown in fig. 19B, the filter member 442 is held (fixed) by the holding member 443 being pressed by the coil spring 446. The peripheral edge of the filter member 442 is fixed to the holding member 443. The ink passes through the central region except the peripheral edge of the filter element 442, and at this time, foreign matter is captured (see the arrow in the figure).

The holding member 443 is disposed in the vicinity of the downstream end 441B within the filter chamber 44, and includes: a frame member 444 having an opening 444A serving as a flow path for ink; and an annular sealing member 445 supported by the frame member 444. A molded article of a hard resin may be used for the frame member 444, and a molded article of a soft resin, rubber, or the like may be used for the sealing member 445. The sealing member 445 is fitted into a seat provided on the rear side surface of the frame member 444. The filter member 442 abuts on the rear surface side of the sealing member 445. The front surface of the frame member 444 is engaged with a stepped portion 441C formed at the downstream end 441B of the inner wall surface 441.

The coil spring 446 presses the peripheral edge portion of the filter member 442 against the rear surface side of the seal member 445. The coil spring 446 is housed in the filter chamber 44 with its coil axis along the ink supply direction (front-rear direction). In detail, the coil spring 446 is assembled to the filter chamber 44 in such a manner that: the rear end 446A of the coil spring 446 is locked to the upstream end 441A of the inner wall surface 441, and the front end 446B presses the peripheral edge of the filter member 442 toward the seal member 445.

According to the structure of the filter chamber 44, the filter member 442 closes the opening 444A of the frame member 444 holding the annular seal member 445. Therefore, foreign matter in the ink can be reliably captured by the filter member 442. Further, the filter member 442 and the holding member 443 can be fixed by the pressing force of the coil spring 446 without using an adhesive or the like. When the liquid supply unit 3 operates, the filter member 442 is placed in the liquid, and the peripheral edge portion as a fixing portion to the holding member 443 is also immersed in the ink. The ink may act as a solvent for the adhesive and the like. Therefore, if the filter member 442 is fixed using an adhesive or the like, the filter member 442 peels off from the holding member 443, or the adhesive or the like is eluted into the ink to become foreign matter. Such a failure can be eliminated by the present embodiment using the urging force of the coil spring 446. Further, by providing the filter chamber 44 as a dedicated chamber for filtering ink, the filter member 442 of the liquid supply unit 3 can be assembled well and the filtering performance can be exhibited reliably.

[ exhaust mechanism part of second Chamber ]

Next, the exhaust mechanism 37 provided in the second chamber 42 will be described with reference to fig. 20(a) to 22(B) in addition to fig. 12 (a). Fig. 20(a) and (B) are perspective views of the lever member 46 as a constituent member of the exhaust mechanism 37, and fig. 20(C) is an exploded perspective view of the lever member 46. Fig. 21(a) and (B) are perspective views showing the positional relationship among the pressing member 5, the opening/closing valve 6, and the lever member 46. Fig. 22(a) and (B) are cross-sections similar to fig. 16(a) and are cross-sectional views for explaining the exhaust operation of the lever member 46. As described above, the air discharge mechanism 37 is used for air discharge at the initial filling of the second chamber 42 with ink, degassing of air bubbles generated by ink, and the like at the initial use and after maintenance.

The exhaust mechanism 37 includes the rod member 46, the seal ring 46C, and the stopper 47 in addition to the above-described projecting portion 426 projecting from the upper end 422 of the second chamber 42. As shown in fig. 12(a), the protrusion 426 protrudes from the uppermost end of the second defining wall 421 defining the second chamber 42, and has an opening for communicating the second chamber 42 with the atmosphere, i.e., a protrusion hole 42A having a circular cross section as a gas discharge hole. By providing the protruding hole 42A at the uppermost position of the second chamber 42, degassing of the second chamber 42 can be reliably performed. The protruding portion 426 includes a large diameter portion 426A located directly above the upper end portion 422 and a small diameter portion 426B continuously provided above the large diameter portion 426A. The large diameter portion 426A is larger than the small diameter portion 426B with respect to the inner diameter of the projection hole 42A.

As shown in fig. 20(C), the lever member 46 has a shovel shape, and includes a rod-like member 461 partially inserted into the protrusion hole 42A and a pressing piece 464 provided continuously therebelow. The lever member 46 is a valve member that changes its posture between a closed posture for closing the projection hole 42A and an open posture for opening the projection hole 42A. In the present embodiment, the posture changing operation of the lever member 46 is interlocked with the posture changing operation of the opening/closing valve 6 by the pressing member 5. Specifically, the open/close valve 6 is allowed to be in the closed position in the state where the rod member 46 is in the closed position, and the position of the open/close valve 6 is changed from the closed position to the open position in the state where the rod member 46 is in the open position.

The rod-like member 461 of the lever member 46 is a cylindrical body having an outer diameter smaller than the bore diameter of the projection hole 42A, and has an upper end 462 and a lower end 463. The upper end portion 462 serves as an input portion for receiving an operation pressing force for pressing the lever member 46 downward from a user. Lower end 463 is connected to pressing piece 464. As shown in fig. 21(a) and (B), the pressing piece 464 functions as a transmission portion that transmits the operation pressing force applied to the upper end portion 462 to the receiving inclined surface 55 of the pressing member 5. An intermittent projection 463A in which a plurality of small projections are arranged in a ring shape in the circumferential direction of the rod 461 is provided slightly above the lower end 463.

The pressing piece 464 has a pressing slope 465 inclined with respect to the axis of the rod 461 and a lower edge 466 extending in the front-rear direction at the lowermost end. The pressing slope 465 is a slope extending upward from the lower edge 466. The pressing slope 465 and the lower edge 466 are portions that interfere with the pair of front and rear receiving slopes 55 of the pressing member 5 when the lever member 46 receives the operation pressing force. The front-rear width of the pressing slope 465 is set to a dimension longer than the interval of the pair of receiving slopes 55. When the pressing slope 465 and the lower end edge 466 abut against the receiving slope 55 and the operation pressing force is transmitted to the pressing member 5, the pressing member 5 rotates leftward about the axis of the fulcrum portion 53, and the open/close valve 6 is changed from the closed position to the open position.

An upper engaging groove 467A and a lower engaging groove 467B are formed near the upper end 462 of the rod 461 and are arranged at an interval in the vertical direction. The upper gasket 46A is fitted into the upper engagement groove 467A, and the lower gasket 46B is fitted into the lower engagement groove 467B. A seal groove 468 is provided near the lower end 463. The outer diameter of the lower end portion 463 is set larger than the outer diameter of the other portion of the rod 461, and a seal groove 468 is formed between the lower end portion 463 and the intermittent projection 463A. Further, an exhaust vertical groove 461A formed by a concave groove is provided over the entire length of the rod 461 in the front-rear direction. The discharge vertical grooves 461A correspond in circumferential position to the trough portions of the intermittent projections 463A.

The rod 461 is provided with a seal ring 46C and a stopper 47. The seal ring 46C is an O-ring having an inner diameter slightly larger than that of the rod 461. The seal ring 46C is fitted around the rod 461 and fitted into the seal groove 468. The outer peripheral surface of the seal ring 46C IS in sliding contact with the inner peripheral surface IS of the large diameter portion 426A of the protrusion 426 in a state attached to the seal groove 468. The stopper 47 is a substantially rectangular plate member, and includes a pivot hole 47H through which the rod 461 is inserted. The stopper 47 is attached to the vicinity of the upper end 462 between the upper engaging groove 467A and the lower engaging groove 467B. The upper and

lower spacers

46A and 46B sandwich the stopper 47, and are fitted into the upper and

lower engagement grooves

467A and 467B, respectively, so as to restrict axial movement of the stopper 47.

The stopper 47 is rotatable around the shaft of the rod-like member 461 while being sandwiched between the upper and

lower spacers

46A, 46B. The stopper 47 is a member that is intended to abut against the upper surface 428A or the lower surface 428B (fig. 22) of the pair of catching claws 428 of the holding frame 427 in response to the up-and-down movement of the lever member 46. When the stopper 47 moves up and down, the stopper rotates so that the longitudinal direction thereof becomes the left-right direction, and passes through the gap between the pair of locking claws 428. The stopper 47 has a pin hole 471 and a locking recess 472. At least when the stopper 47 abuts on the upper surface 428A, as shown in fig. 12(a), the cotter-type pin member 48 is fitted into the pin hole 471 and the locking recess 472, and rotation and separation of the stopper 47 are prevented, that is, the stopper 47 is fixed. The stopper 47, the pin member 48, and the pair of locking claws 428 function as a fixing mechanism for fixing the posture of the rod member 46.

Next, the operation of the lever member 46 will be described. Fig. 22(a) is a sectional view showing a state before the lever member 46 operates, and fig. 22(B) is a sectional view showing a state in which the exhaust of the second chamber 42 is performed by the operation of the lever member 46. Fig. 22(a) shows a state in which the upper end 462 of the lever member 46 is not receiving the operation pressing force, that is, a closed posture in which the lever member 46 closes the projection hole 42A. On the other hand, fig. 22(B) shows a state in which the upper end portion 462 is pressed downward and an operation pressing force is applied, that is, an open posture in which the lever member 46 opens the protruding hole 42A.

The closed posture is formed by fixing the stopper 47 to the upper surface 428A of the locking claw 428 in a state where both are in contact with each other. By this fixation, the lever member 46 is lifted upward. This state is a state in which the intermittent projection 463A and the lower end 463 of the rod 461 are accommodated in the large diameter portion 426A of the projection 426. That IS, the outer peripheral surface of the seal ring 46C IS in contact with the inner peripheral surface IS of the large diameter portion 426A. Therefore, the protruding hole 42A is in a closed state. The pressing piece 464 (pressing slope 465 and lower end edge 466) of the lever member 46 is in a state of being separated from the receiving slope 55 of the pressing member 5, and does not apply any force to the pressing member 5. Therefore, the opening/closing valve 6 maintains the closed position.

On the other hand, if the lever member 46 IS lowered by the operation pressing force to assume the open posture, the intermittent projection 463A and the lower end 463 are also lowered, and the seal ring 46C IS separated from the inner circumferential surface IS. Accordingly, the air passage formed by the trough portion of the intermittent projection 463A and the air discharge vertical groove 461A of the rod-like member 461 communicates with the space in the second chamber 42. That is, the protruding hole 42A is opened, and the second chamber 42 communicates with the outside air. Therefore, the air staying in the second chamber 42 can be discharged to the outside through the protruding holes 42A.

Further, if the lever member 46 is in the open posture, the operation pressing force is transmitted to the urging member 5. As shown in fig. 22(B), the pressing slope 465 and the lower edge 466 press the receiving slope 55. When the receiving slope 55 is pressed, the pressing member 5 (the disc portion 51) rotates leftward around the axis of the fulcrum portion 53. As described above, if the pressing member 5 is rotated leftward, the on-off valve 6 is pressed leftward by the link projection 54, and the posture of the on-off valve 6 is changed from the closed posture to the open posture. Accordingly, the communication port 43 is not closed, and the first chamber 41 and the second chamber 42 are in a communicated state.

The open posture is formed by the stopper 47 abutting against the lower surface 428B of the locking claw 428. That is, when the open posture is adopted, the stopper 47 is pushed down to enter a state below the locking claw 428. Then, the pressing piece 464 is pressed by the receiving slope 55, and the pressing member 5 rotates against the biasing force of the biasing spring 45, so that the biasing force of the biasing spring 45 is applied to the pressing piece 464. That is, a force for lifting the lever member 46 upward acts on the lever member. By this urging force, the stopper 47 abuts against the lower surface 428B of the locking claw 428, and the open posture is maintained.

Thus, if the lever member 46 is in the open posture, the inlet of the fluid (the communication port 43) and the outlet of the fluid (the protrusion hole 42A) to the second chamber 42 are secured. Therefore, at the time of initial use, the filling operation of the ink from the first chamber 41 to the second chamber 42 through the communication port 43 can be smoothly performed by the water head difference supply while discharging the air of the second chamber 42 from the protrusion hole 42A. Further, when the air amount in the second chamber 42 increases due to the generation of bubbles or the like from the ink (since the ink level in the second chamber 42 decreases, it can be confirmed by the monitor tube 36), the air in the second chamber 42 can be easily exhausted by setting the lever member 46 to the open posture.

In the above embodiment, the posture of the opening/closing valve 6 is changed to the open posture in conjunction with the operation of the lever member 46 in the open posture by the pressing member 5 including the pressure receiving portion 5A receiving the displacement force from the atmospheric pressure detection membrane 7 and the link protrusion 54 pressing the opening/closing valve 6 by the displacement force received by the pressure receiving portion 5A. That is, the structure can ensure the inlet and outlet of the fluid to and from the second chamber 42 by one operation of the lever member 46. Therefore, the user can easily perform the air discharging operation of the second chamber 42. Further, since the air discharge mechanism 37 is disposed on the upper surface of the tank portion 31, even in a state where the plurality of liquid supply units 3 are mounted on the rack 2, as shown in fig. 4, the user can contact the liquid supply units from the front side of the rack 2 to perform the air discharge operation for the liquid supply units 3.

[ procedure of exhaust action ]

Next, an example of the exhaust operation of the exhaust mechanism 37 will be described with reference to fig. 23(a) to 24 (B). Fig. 23(a) is a perspective view of the exhaust mechanism 37 corresponding to the state of fig. 22(a), fig. 23(B) and 24(a) are perspective views showing the operation of the lever member 46, and fig. 24(B) is a perspective view of the exhaust mechanism 37 corresponding to the state of fig. 22 (B).

In the closed posture of fig. 22(a) and 23(a), as described above, the stopper 47 is fixed by the pin member 48 in a state of abutting against the upper surface 428A of the locking claw 428. The stopper 47 is rotated so that its longitudinal direction is oriented in the front-rear direction, and the front end side is overlapped with the front-side locking claw 428 and the rear end side is overlapped with the rear-side locking claw 428. The pin hole 471 and the locking recess 472 of the stopper 47 are located on the distal end side by the rotation. The front locking claw 428 is provided with a notch at a position corresponding to the pin hole 471. The vertical portion 481 of the cotter pin-type pin member 48 is inserted through the pin hole 471, and the engaging portion 482, the lower end side of which is bent outward, is fitted into the locking recess 472, whereby the stopper 47 is fixed to the locking claw 428. In this state, the lever member 46 IS suspended upward, the seal ring 46C comes into contact with the inner peripheral surface IS of the projection hole 42A to exert a sealing effect, and the pressing slope 465 and the receiving slope 55 are separated.

When the air discharge operation of the second chamber 42 is performed, as shown in fig. 23(B), first, the operator pulls out the pin member 48 from the stopper 47. Accordingly, the stopper 47 is in a state rotatable around the shaft of the rod-like member 461. Next, as shown in fig. 24(a), the operator turns the stopper 47 by 90 ° so that the longitudinal direction thereof is oriented in the left-right direction. By this rotation, the stopper 47 is in a state of being able to pass through the gap between the pair of front and rear locking claws 428 in the up-down direction, and in this state, the operator presses the upper end part 462 to press down the lever member 46. This depression proceeds until the upper surface of the stopper 47 reaches below the lower surface 428B of the catch pawl 428.

Thereafter, as shown in fig. 24(B), the worker turns the stopper 47 by 90 ° so that the longitudinal direction thereof is oriented in the front-rear direction. Accordingly, the stopper 47 has a front end side overlapping below the front locking claw 428 and a rear end side overlapping below the rear locking claw 428. In this state, as shown in fig. 22(B), the lever member 46 IS pressed downward, and the seal ring 46C IS separated from the inner circumferential surface IS of the projection hole 42A, and IS in an open posture in which the sealing effect IS lost. The operation pressing force applied to the upper end 462 is transmitted from the pressing piece 464 to the receiving slope 55, and the pressing member 5 is rotated against the urging force of the urging spring 45. The stopper 47 is pushed against the lower surface 428B of the locking claw 428 by the repulsive force of the biasing spring 45 at this time, and the lever member 46 for the open posture is fixed.

In this way, even if the lever member 46 is in any of the closed posture and the open posture, these postures can be easily maintained by the locking claws 428. For example, when the second chamber 42 is filled with a liquid at the time of initial use, the rod member 46 needs to be maintained in an open posture because the second chamber 42 needs to be vented. At this time, the operator only has to perform an operation of pressing the upper end 462 of the rod member 46 and inserting the stopper 47 into the lower surface 428B of the locking claw 428. Therefore, the worker does not need to continuously press the upper end portion 462, and the operability thereof can be improved. In addition, when the liquid supply unit 3 is normally used, it is necessary to set the lever member 46 to the closed posture. At this time, the stopper 47 may be overlapped on the upper surface 428A of the locking claw 428 and fixed by the pin member 48, and this can be performed by a simple operation.

[ backflow prevention mechanism ]

Next, the configuration of the backflow prevention mechanism 38 that prevents backflow of the ink pressurized by the pump 9 into the second chamber 42 when the pressure purge mode described with reference to fig. 9(a) is executed will be described. Fig. 25 is a front-rear sectional view of the liquid supply unit 3 including a section of the backflow prevention mechanism 38, fig. 26 is an exploded perspective view of the backflow prevention mechanism 38, and fig. 27(a) to (C) are perspective views of the backflow prevention mechanism 38. Fig. 28(a) and (B) are enlarged views of a portion a3 of fig. 25, fig. 28(a) is a sectional view showing a state of the backflow prevention mechanism portion 38 in the print mode, and fig. 28(B) is a sectional view showing a state of the backflow prevention mechanism portion 38 in the pressure purge mode.

The backflow prevention mechanism 38 includes a valve pipe 81, a branch head 82, a ball 83, a seal member 84, a coil spring 85, and an O-ring 86. The valve line 81 is a member integrated with the lower end portion 423 of the second chamber 42, and other elements are assembled to the valve line 81. Fig. 27(a) and (B) are perspective views of the backflow prevention mechanism 38 excluding the valve pipe 81, and fig. 27(C) is a perspective view of the branch head 82 as viewed from below.

The valve pipe 81 is a pipe extending vertically downward from a supply hole 42H (liquid discharge port) penetrating through a lower end portion 423 (lowermost end portion) of the second chamber 42, and is a portion integrated with the second defining wall 421. The valve line 81 is for providing an ink flow path connecting the second chamber 42 and the downstream pipe 34, and constitutes a part of an ink supply passage from the second chamber 42 to the ink ejecting section 22. In order to lock the branch head 82, a locking piece 811 projects from the outer peripheral surface of the valve pipe 81, and a fitting annular projection 812 projects from the inner peripheral surface.

The branch head 82 is a member forming the aforementioned merging portion a based on fig. 7 to 9. The branch head 82 includes a first inlet port 821, a second inlet port 822, an outlet port 823, a housing section 824, a locking window 825, a cutout section 826, and a fitting claw 827. The first inlet port 821 is a port connected to the second chamber 42, and in the present embodiment, communicates with the second chamber 42 via the valve line 81. The second inlet port 822 is a port to which the downstream end of the bypass pipe 32P (bypass downstream pipe BP2) is connected. The outlet port 823 is the port to which the upstream end 341 of the downstream pipe 34 is connected.

The case section 824 is formed of a pair of arcuate pieces arranged to face each other outside the first inlet port 821 facing downward. The valve line 81 enters a gap between the pair of housing portions 824 and the first inlet port 821. The locking window 825 is an opening provided in the pair of case portions 824, and is an opening through which the locking piece 811 of the valve pipe 81 engages. The cutout 826 is a portion in which a part of the peripheral wall of the tubular first inlet port 821 is cut, and is a portion for ensuring a flow path of ink. The fitting claw 827 is a hook-shaped portion protruding upward from the upper end of the first inlet port 821, and engages with the fitting annular protrusion 812 of the valve pipe 81. That is, the branch head 82 is fixed to the valve pipe 81 by the engagement of the locking piece 811 with the locking window 825 at the inner periphery of the valve pipe 81 and the engagement of the fitting annular protrusion 812 with the fitting claw 827 at the outer periphery. The upper end edge 828 of the first inlet port 821 serves as a ball receiving portion for receiving a ball 83 described later.

The ball 83 is accommodated in the valve pipe 81 so as to be movable in the ink supply direction, and functions as a valve. The outer diameter of the ball 83 is smaller than the inner diameter of the valve pipe 81 and smaller than the inner diameter of the coil spring 85. As a material for forming the spherical body 83, various materials can be used, but it is preferable to use a material having a specific gravity of 2 times or less with respect to the specific gravity of the ink, and it is particularly preferable to use a material having a specific gravity of 1.1 times to 1.5 times with respect to the ink. If the material is in this range, the specific gravity of the ball 83 is greater than that of the ink, so that the ball 83 is easily lowered by its own weight in the valve pipe 81, and the specific gravity of the ball 83 is close to that of the ink, so that the ball 83 can be quickly raised in the valve pipe 81 when the pressure purge is performed.

Generally, ink used in an ink jet printer is an aqueous liquid having a specific gravity of 1 or a specific gravity close thereto. Therefore, as the material of the spherical body 83, a material having a specific gravity of < 2 is preferably selected. The material preferably has chemical resistance and abrasion resistance which do not deteriorate even when the material is constantly in contact with ink. From these viewpoints, it is particularly preferable to use polyacetal (specific gravity ≈ 1.42), polybutylene terephthalate (specific gravity ≈ 1.31 to 1.38), polyvinyl chloride (specific gravity ≈ 1.35 to 1.45), and polyethylene terephthalate (specific gravity ≈ 1.34 to 1.39) as the material of the spheres 83.

The seal member 84 is a ring-shaped seal element, and as shown in fig. 28(a) and (B), for example, the seal member 84 is seated on a seat portion 813 provided on the upper end side of the valve pipe 81 above the ball 83. The inner diameter (through hole) of the seal member 84 is set smaller than the outer diameter of the ball 83. As shown in fig. 28(a), when the ball 83 moves downward away from the seal member 84, the valve line 81 opens. On the other hand, as shown in fig. 28(B), when the ball 83 abuts against the seal member 84, the valve line 81 is closed.

The coil spring 85 is a compression spring that is mounted in the valve pipe 81 such that the lower end thereof abuts against the seal member 84 and the upper end thereof abuts against the lower end edge 828 of the first inlet port 821 of the branch head 82. The coil spring 85 applies a force to the seal member 84 toward the seat portion 813, whereby the seal member 84 is always pressed against the seat portion 813. The ball 83 is housed inside the coil spring 85, and the coil spring 85 also functions to guide the movement of the ball 83 in the ink supply direction. Therefore, the play of the ball 83 in the valve pipe 81 is restricted, and the valve structure established by the contact or separation of the ball 83 with respect to the seal member 84 can be stabilized.

An O-ring 86 seals the interface of valve conduit 81 and branch head 82. The O-ring 86 is fitted to the outer peripheral surface of the first inlet port 821 and abuts against the protruding base 829 of the first inlet port 821.

Fig. 25 shows the pump 9 housed in the pump section 32. The pump 9 is disposed in the bypass pipe 32P, and pressurizes the ink flowing through the bypass pipe 32P. The pump 9 is a tube pump including an eccentric cam 91 and a squeeze tube 92. A camshaft 93 (fig. 4) serving as a rotation shaft of the eccentric cam 91 is inserted into the shaft hole 91A of the eccentric cam 91. A rotational driving force is applied to the eccentric cam 91 from an unillustrated drive gear. The pressing tube 92 is disposed on the circumferential surface of the eccentric cam 91, and is pressed by the rotation of the eccentric cam 91 around the cam shaft 93, thereby sending out the liquid (ink) in the tube from one end side to the other end side. In the present embodiment, the extruded tube 92 is a tube integrated with the bypass tube 32P. That is, one end side of the pressing pipe 92 serves as a bypass upstream pipe BP1 communicating with the bypass communication chamber 413 of the first chamber 41, the other end side serves as a bypass downstream pipe BP2 communicating with the second inlet port 822 of the branch head 82, and the central portion serves as a pressing portion disposed on the circumferential surface of the eccentric cam 91.

As already described, the pump 9 is in a stopped state in the printing mode shown in fig. 7. At this time, the eccentric cam 91 crushes the pressing tube 92 to be in a stopped state, and thus the ink supply passage through the bypass tube 32P is closed. On the other hand, in the circulation mode shown in fig. 8 and the pressure purge mode shown in fig. 9(a), the pump 9 is driven in the normal direction. In fig. 25, the normal rotation direction of the eccentric cam 91 is the counterclockwise direction. By the normal rotation driving of the pump 9, the ink is sucked from the first chamber 41 through the bypass upstream pipe BP1, and flows from the bypass downstream pipe BP2 toward the backflow prevention mechanism 38 as the junction a. Further, if the pump 9 is driven in reverse, the second chamber 42 and the downstream pipe 34 are depressurized through the bypass pipe 32P and the branch head 82 as shown in fig. 9 (B).

Next, the operation of the backflow prevention mechanism 38 will be described. In the print mode (first state), ink is supplied from the second chamber 42 to the head unit 21 through a supply path passing through the backflow prevention mechanism portion 38 and the downstream pipe 34. In this print mode, as shown in fig. 28a, the ball 83 is separated downward from the seal member 84 and is in a state of being seated on the upper end edge 828 (ball receiving portion) of the branch head 82. This is because the specific gravity of the spherical body 83 is larger than that of the ink, and the spherical body 83 is lowered by its own weight. Further, the supply path from the second chamber 42 to the downstream pipe 34 is maintained at a negative pressure in the print mode, and the ink ejection portion 22 of the head unit 21 sucks ink present in the supply path every time ink droplets are ejected, which also helps to maintain the state in which the balls 83 land on the upper end edge 828.

Since the ball 83 is separated from the sealing member 84, the supply hole 42H is opened. Further, since the cutout section 826 is provided at the upper end edge 828 of the first inlet port 821 on which the ball 83 drops, a passage of ink is ensured. Therefore, the ink in the second chamber 42 can pass through the branch head 82 from the second chamber 42 toward the downstream pipe 34 as indicated by an arrow F1 in the figure.

Fig. 28B is a sectional view showing a state of the backflow prevention mechanism 38 in the pressure purge mode (second state). In the pressure purge mode, ink pressurized by the bypass pipe 32P is supplied to the second inlet port 822 (junction portion a) of the branch header 82 by the normal rotation driving of the pump 9. Therefore, the pressurized ink is present in the bypass pipe 32P and the downstream pipe 34 located on the downstream side of the merging portion a. At this time, the ink is pressurized to a high pressure exceeding 100 kPa. If such a high pressure is applied to the second chamber 42, the atmospheric pressure detection film 7 defining a part of the second chamber 42 may be broken or peeled off from the mounting portion of the second defining wall 421.

However, in the present embodiment, the sphere 83 is pressed so as to rise (move to the upstream side in the ink supply direction) by the pressing force applied to the merging portion a, and the sphere 83 abuts on the seal member 84. That is, the ball 83 floats upward by the pressing, and is fitted into the ring of the seal member 84. The supply hole 42H is closed by the ball 83 coming into contact with the seal member 84 pressed against the seat portion 813 by the coil spring 85. That is, in the ink supply path in the print mode, the ink supply path located on the upstream side of the merging portion a and the second chamber 42 are blocked from the pressurization of the pressurized ink. Therefore, damage and the like of the atmospheric pressure detection membrane 7 can be prevented in advance.

In addition, the present embodiment has an advantage that it is difficult to supply ink containing air to the head unit 21. Air dissolved in the ink and air mixed when the liquid supply unit 3 is filled with the ink liquid enter the head unit 21 in a state of being included in the ink, and once entering the individual channels 26 and the common channel 27 (fig. 6(a)), the air is hardly discharged, and sometimes cannot be discharged even if the pressure purge is performed. At this time, the ejection of ink from the ink ejection hole 22H is hindered. However, in the present embodiment, the second chamber 42, the backflow prevention mechanism 38, and the downstream pipe 34 are arranged in this order from the top toward the bottom. Therefore, air generated from the ink stored in the second chamber 42 or air mixed in the second chamber 42 does not flow downward toward the backflow prevention mechanism portion 38 and the downstream pipe 34. Therefore, the ink containing air can be prevented from being directed to the head unit 21, and the amount of the ejection portion of the head unit 21 can be prevented.

Even if air is mixed into the branch head 82 or the downstream pipe 34, the air can be discharged from the vertical portion 82A into the second chamber 42 through the valve pipe 81 and the supply hole 42H by the floating action of the air bubbles. The air can be discharged from the second chamber 42 by the air discharge mechanism 37. Therefore, the air can be prevented from occupying the volume in the second chamber 42 excessively.

[ double protection mechanism using umbrella valve ]

As described above, in the present embodiment, the backflow prevention mechanism 38 is provided to prevent the ink pressurized in the pressure purge mode from flowing backward into the second chamber 42. However, due to some failure of the backflow prevention mechanism 38, for example, a failure in the operation of the ball 83, a pressurizing force may act on the second chamber 42. In view of this, the present embodiment includes a double protection mechanism and a mechanism for releasing the pressure of the open/close valve 6. That is, the opening/closing valve 6 includes a pressure release mechanism that releases the pressure from the second chamber 42 toward the first chamber 41 when the pressure relationship between the second chamber 42 and the first chamber 41 is negative and the atmospheric pressure + ρ gh is reversed in the normal state and the pressure in the second chamber 42 is higher than that in the first chamber 41.

Responsible for said pressure release mechanism is an umbrella valve 66 opening and closing the valve 6. As described with reference to fig. 16(a) to 17(B), when the second chamber 42 is at a negative pressure lower than a predetermined threshold value, the umbrella valve 66 closes the communication port 43 by the sealing surface 67 abutting against the sealing wall surface 43S. Accordingly, the ink is inhibited from flowing from the first chamber 41 into the second chamber 42. On the other hand, if the second chamber 42 reaches a negative pressure exceeding a predetermined threshold value, the umbrella valve 66 moves leftward together with the valve support 61 linked to the pressing member 5, and the sealing surface 67 separates from the sealing wall surface 43S to open the communication port 43 (unblocks). Accordingly, the ink is allowed to flow from the first chamber 41 into the second chamber 42.

In addition, when the pressure relationship between the second chamber 42 and the first chamber 41 is reversed due to, for example, the pressure of the pressurized ink in the pressure purge mode being applied to the second chamber 42, the umbrella valve 66 opens the communication port 43 solely by the umbrella valve 66. That is, the umbrella valve 66 releases the communication port 43 from the closed state without being assisted by the pressing of the pressing member 5, and releases the pressure of the second chamber 42 to the first chamber 41. That is, if a predetermined pressure is applied to the right side of the umbrella part 661 (the sealing surface 67) of the umbrella valve 66, the umbrella shape is reversed.

Fig. 29(a) is a sectional view showing a state where the communication port 43 is closed by the umbrella valve 66, and fig. 29(B) is a sectional view showing a state where the communication port 43 is opened by the umbrella valve 66. The state of fig. 29(a) is equal to the state of fig. 16(B) described previously. The umbrella portion 661 has an umbrella shape protruding leftward. The valve support 61 is positioned rightmost by the biasing force of the biasing spring 45, and the annular contact portion 62A thereof contacts the stepped portion 43C of the communication port 43. Therefore, the seal surface 67 is in contact with the seal wall surface 43S.

The state of fig. 29(B) shows a state in which the umbrella shape of the umbrella portion 661 of the umbrella valve 66 is inverted by the pressure applied from the second chamber 42 side. That is, the umbrella portion 661 deforms into an umbrella shape that is convex toward the right. The reverse rotation state is formed when the pressure of the second chamber 42 is higher than the first chamber 41 by a predetermined value. In the present embodiment, a case is assumed in which a high positive pressure is applied to the second chamber 42 due to the pressurization purge, and as a result, the pressure of the second chamber 42 becomes higher than the pressure of the first chamber 41 of the atmospheric pressure + ρ gh. The predetermined value depends on the reverse pressure of the umbrella part 661. The inversion pressure is set to a value lower than the rupture strength of the atmospheric pressure detection membrane 7 or the mounting strength of the atmospheric pressure detection membrane 7 to the second defining wall 421.

When the second chamber 42 is pressurized, the pressing member 5 does not rotate leftward. That is, the pressing member 5 does not generate a pressing force that presses the opening/closing valve 6 leftward. This is because the atmospheric pressure detection membrane 7 is displaced to the side that expands rightward by the increase in pressure of the second chamber 42, and no displacement force is applied to the pressure receiving portion 5A. Therefore, the valve support 61 is maintained in the rightmost state by the biasing force of the biasing spring 45.

However, even if the valve support 61 does not move, the umbrella shape of the umbrella portion 661 is reversed, and the seal surface 67 is separated from the seal wall surface 43S, and a gap G is formed between the two. Therefore, the communication port 43 is in an opened state. Accordingly, the pressurized ink (pressure) in the second chamber 42 is discharged (released) to the first chamber 41 side through the communication port 43. Therefore, excessive force can be prevented from acting on the atmospheric pressure detection membrane 7 itself or the mounting portion thereof, and breakage can be prevented.

[ flow of ink in each mode ]

Next, the flow of ink in each mode of the liquid supply unit 3 will be described. Fig. 30 is a perspective view showing the flow of ink in the printing mode, fig. 31 is a perspective view showing the flow of ink in the pressure purge mode, and fig. 32 is a perspective view showing the flow of ink in the circulation mode.

In the print mode (fig. 30), since the ink is not circulated through the return pipe 35, the return pipe 35 is closed by the clip 35V. Of course, the supply valve 33V (fig. 5) is in an open state. The ink ejected from the ink cartridge IC enters the filter chamber 44 through the upstream pipe 33 by the water head difference as shown by an arrow F11 in fig. 30. When the filter chamber 44 passes through the filter member 442, solid foreign matter contained in the ink is removed. And thereafter into the first chamber 41.

When the opening/closing valve 6 is opened by the operation of the pressing member 5, ink is stored from the first chamber 41 to the second chamber 42 through the communication port 43 as indicated by an arrow F12. The ink in the second chamber 42 is sucked by the ink ejecting operation in the ink ejecting section 22, and passes through the supply hole 42H and the backflow preventing mechanism section 38 in this order to enter the downstream pipe 34. Thereafter, as indicated by an arrow F13, the ink enters the common channel 27 of the head unit 21 via the end pipe 24 (fig. 6 (a)). Then, the ink is ejected from each ink ejection hole 22H through the individual passage 26 (arrow F14).

In the pressure purge mode (fig. 31), since the ink using the return tube 35 is not circulated, the return tube 35 is closed by the clamp 35V. The supply valve 33V is in an open state. In the pressure purge mode, the pump 9 is normally operated, and ink is forcibly supplied to the head unit 21 without depending on the head difference. If the pump 9 is actuated, as indicated by arrow F21, ink enters the filter chamber 44 through the upstream pipe 33 and further into the first chamber 41. Then, as indicated by an arrow F22, the ink enters the bypass upstream pipe BP1 via the bypass communication chamber 413 without going toward the second chamber 42.

The ink is pressurized by the pressing operation of the pump 9 and is sent to the downstream side. That is, as indicated by an arrow F23, the ink is sent from the bypass downstream pipe BP2 to the downstream pipe 34. As described above, the backflow prevention mechanism 38 is provided at the junction a of the downstream pipe 34 of the bypass downstream pipe BP2, and therefore, the ink does not flow backward to the second chamber 42 side. Thereafter, as indicated by an arrow F24, the ink enters the common channel 27 of the head unit 21 via the end pipe 24 (fig. 6 (a)). Then, through the individual channels 26, the ink is ejected from the ink ejection holes 22H at high pressure (arrow F25). Accordingly, foreign substances blocking the ink ejection holes 22H, air accumulated in the individual channels 26, and the like are removed.

In the circulation mode (fig. 32), since the ink is circulated by using the return pipe 35, the closed state of the clip 35V is released, and the return pipe 35 is opened. On the other hand, since ink is circulated between the liquid supply unit 3 and the head unit 21, the supply valve 33V (fig. 5) is in a closed state. Accordingly, a closed ink circulation path is formed by the bypass tube 32P, the downstream tube 34, the common channel 27 of the head unit 21, the return tube 35, the return communication chamber 414, and the bypass communication chamber 413. In this circulation mode, as described with reference to fig. 8, the pump 9 is also operated in the normal rotation direction.

If the pump 9 is operated, circulation of ink in the ink circulation path is started. That is, by the operation of the pump 9, ink is introduced from the bypass communication chamber 413 to the bypass upstream pipe BP1 as indicated by an arrow F31, and then sent to the bypass downstream pipe BP2 as indicated by an arrow F32. Thereafter, the ink flows into the head unit 21 through the junction a, the downstream pipe 34, and the end pipe 24 (arrow F33), passes through the common passage 27 in the head unit 21, and enters the recovery pipe 25 (arrow F34). Then, as indicated by an arrow F35, the ink returns from the recovery tube 25 to the bypass communication chamber 413 through the return tube 35, the return communication chamber 414, and the junction b in this order. At this time, since the supply valve 33V is closed, the return pipe 35 and the common channel 27, which are sucked by the pump 9, have a negative pressure. Therefore, the ink does not leak from the ink ejection hole 22H during the ink circulation.

If the circulation mode is executed, the ink can be circulated within the ink circulation path as described above. In other words, the ink once conveyed to the head unit 21 side can be returned to the liquid supply unit 3 side using the return pipe 35. Therefore, even if ink containing air is sent in or the like and air enters the head unit 21 side, the air can be recovered to the liquid supply unit 3 side together with the ink by the circulation. The air (bubbles) collected to the liquid supply unit 3 side enters the first chamber 41 above from the return communication chamber 414 by buoyancy, and moves from the communication port 43 disposed in the uppermost vicinity of the first chamber 41 to the second chamber 42. The operator checks the state of air accumulation in the second chamber 42 using the monitor tube 36, and operates the exhaust mechanism 37 in a timely manner to exhaust the air from the second chamber 42 to the outside.

As described above, by executing the circulation mode, air can be prevented from staying in the vicinity of the individual channels 26 and the ink ejection holes 22H of the head unit 21. The air introduced into the head unit 21 side can also be removed by the pressurized purge mode. However, once the air entering the head unit 21 is difficult to be discharged, it is sometimes necessary to perform pressure cleaning of discharging a considerable amount of ink. Therefore, there is a problem that a large amount of ink is consumed only for exhausting air from the head unit 21. However, since the ink is circulated and the air is recovered to the liquid supply unit 3 according to the circulation mode, the ink is not consumed. In the circulation mode, the ink may be circulated through the ink circulation path, and the high pressure of the ink is not required as in the pressure purge mode, and therefore, the low speed operation of the pump 9 is sufficient. Therefore, it is possible to avoid a large pressure load from being applied to the liquid supply unit 3, and to prevent the atmospheric pressure detection membrane 7 and the sealing membrane 7A from being damaged.

[ liquid ejecting head of second embodiment ]

Next, a liquid supply unit 3A according to a second embodiment having a configuration different from that of the liquid supply unit 3 described above will be described. Fig. 33(a) is a front view, fig. 33(B) is a side view, and fig. 33(C) is a top view of the liquid supply unit 3A. Fig. 34 is a perspective view showing an internal structure of the liquid supply unit 3A on the first chamber 241 side, and fig. 35 is a perspective view showing an internal structure of the second chamber 242 side. Fig. 36(a) is an exploded perspective view of the liquid supply unit 3A viewed from the second chamber 242 side, and fig. 36(B) is an exploded perspective view of the liquid supply unit 3A viewed from the first chamber 241 side. Fig. 37 is a perspective view of the main body 230 in an exploded perspective view of the backflow prevention mechanism 238.

The liquid supply unit 3A includes a main body 230 having a tank portion 231 and a pump portion 232, an upstream pipe 233, a downstream pipe 234, a bypass pipe 235, an exhaust mechanism 237, a backflow prevention mechanism 238, a pressing member 50, an opening/closing valve 6, and an atmospheric pressure detection membrane 70. Further, the liquid supply unit 3A includes: a monitor tube 236 for monitoring the ink level of the second chamber 242; a communication pipe 232P communicating the pump portion 232 with the first chamber 241; and a closing film 70A constituting a part of the wall surface defining the first chamber 241.

The main body 230 includes a base substrate 300 formed of a flat plate extending in the front-rear direction. The front side of the base 300 is a tank portion substrate 310 (wall portion) serving as a substrate of the tank portion 231, and the rear side is a pump portion casing 320 having a casing structure in the pump portion 232. A first chamber 241 (upstream chamber) is disposed on the left side of the tank substrate 310, and a second chamber 242 (pressure chamber) is disposed on the right side. A communication port 243 for communicating the first chamber 241 and the second chamber 242 is bored in the tank portion substrate 310. An opening/closing valve 6 similar to that of the first embodiment is disposed in the communication port 243.

The first chamber 241 has an L-shape when viewed substantially in plan. The first chamber 241 is defined by a first defining wall 2411 projecting leftward from the tank portion base plate 310. An ink inflow port 2412 is formed through the uppermost wall of the first defining walls 2411. An inlet port 2417 (fig. 37) formed by a receiving plug is provided upright on the outer surface of the first defining wall 2411 corresponding to the ink inlet 2412. The downstream end 332 of the upstream pipe 233 is inserted into the inflow port 2417. That is, the inflow port 2412 is an opening that communicates the ink cartridge IC with the first chamber 241, and ink flows into the first chamber 241 from the inflow port 2412 by a water head difference.

The bottom wall portion 2413 of the first delimiting wall 2411 is located at the lower end of the tank portion base plate 310. A purge port 2414 is provided at a rear side wall of the first delimiting wall 2411 adjacent to the bottom wall portion 2413. The upstream end of the communication pipe 232P is connected to the purge port 2414. A spring seat 2415 formed of a cylindrical hollow cavity is provided in the vicinity of the center of the first chamber 241 in the vertical direction in a protruding manner. The spring seat 2415 is a cavity that houses the biasing spring 245, and opens toward the second chamber 242 side.

The communication port 243 is located above the spring seat 2415 in the first chamber 241. The first chamber 241 is not subjected to a pressure reduction process or the like, and the pressure P obtained by the head difference ρ gh is applied to the first chamber 241 in addition to the atmospheric pressure. If ink flows in from the inflow port 2412, the ink starts to accumulate from the bottom wall 2413. If the liquid level of the ink exceeds the communication port 243, the ink can be supplied to the second chamber 242 through the communication port 243. Further, when the pump 9 housed in the pump section 232 is operated, the ink stored in the first chamber 241 is sucked through the purge port 2414 and the communication pipe 232P, and the ink that has been pressurized is supplied to the head unit 21 through the bypass pipe 235 and the downstream pipe 234.

Referring to fig. 35 and 37, the second chamber 242 has a circular shape when viewed substantially in a plan view. The second chamber 242 is defined by a second defining wall 2421 provided to protrude rightward from the tank portion substrate 310. The second defining wall 2421 has a cylindrical wall 2422 having a cylindrical shape and an upper wall 2423 formed of a rectangular portion protrudingly provided above the cylindrical wall 2422. The spring seat 2415 is recessed in the can base plate 310 at the center of the area surrounded by the cylindrical wall 2422, that is, at a position concentric with the cylindrical wall 2422. The communication port 243 is disposed above the spring seat 2415 on a vertical line passing through the center point of the spring seat 2415.

A communication chamber 244 (a part of the second supply passage) is continuously provided at a lower end of the second chamber 242. Communication room 244 is a rectangular space elongated in the front-rear direction, and linearly extends from the lower end of cylindrical wall 2422 toward the front. The communication chamber 244 is delimited by a wall 2441. A lower passage 2424 that communicates the second chamber 242 with the communication chamber 244 is provided at the lower end of the cylindrical wall 2422. Wall portion 2441 is connected to cylindrical wall 2422 at the location of lower passage 2424. The communication chamber 244 is a space connecting the second chamber 242 and the downstream pipe 234, is a space set to a negative pressure, and substantially constitutes a part of the second chamber 242.

A pair of front and rear support plates 2425 protrude rightward from the tank base plate 310 in a region surrounded by the upper wall 2423 of the second chamber 242. The pair of support plates 2425 are respectively provided with pivot support parts 2426 that pivotally support the pressing member 50. A protrusion 2427 and an upper monitor port 2428 are provided to protrude upward from a top wall 2423A constituting the uppermost portion of the upper wall 2423 (defining the top wall of the second chamber 242). The protrusion 2427 has a protrusion hole therein as an opening for communicating the second chamber 242 with the atmosphere. The protrusion 2427 constitutes a part of the exhaust mechanism 237, and a lever member 246 and a return spring 247, which will be described later, are assembled.

An upper monitor hole 242B is bored in the ceiling wall 2423A on the front side of the protrusion 2427. Also, a lower watch hole 2444 is bored through a top wall 2442 of a wall 2441 defining the communication room 244. An upper monitor port 2428 is provided upright on the top wall 2423A corresponding to the upper monitor hole 242B. A lower monitor port 2445 is provided upright on the top wall 2442 corresponding to the lower monitor hole 2444. The monitor tube 236 is connected at an upper end to the upper monitor port 2428 and at a lower end to the lower monitor port 2445. That is, the monitor tube 236 communicates with the upper end side and the lower end side of the second chamber 242, and the ink level in the monitor tube 236 and the ink level in the second chamber 242 are interlocked. The monitor tube 236 is formed of a transparent resin tube. Therefore, the user can know the ink level in the second chamber 242 by visually checking the monitor tube 236.

The backflow prevention mechanism 238 is provided on the top wall 2442 near the front end of the communication chamber 244. A supply hole 2443 is perforated in the top wall 2442 corresponding to the backflow prevention mechanism portion 238. The upstream end 341 of the downstream pipe 234 is connected to the backflow prevention mechanism 238. The ink stored in the second chamber 242 is supplied to the downstream pipe 234 through the supply hole 2443 and the backflow prevention mechanism 238 so as to be sucked by the ink discharge unit 22 (fig. 5). The backflow prevention mechanism 238 will be described in detail later.

Referring to fig. 36(a) and (B), the left side opening of the first chamber 241 is closed by a closing film 70A made of resin. The closing film 70A has an outer shape conforming to a wall shape of the first defining wall 2411 when viewed from the left. The closing film 70A closes the opening of the first chamber 241 by welding or adhering the peripheral edge portion of the closing film 70A to the end face of the first delimiting wall 2411.

The right-side opening of the second chamber 242 is closed by an atmospheric pressure detection membrane 70 formed of a flexible resin membrane member. The atmospheric pressure detection membrane 70 has an outer shape conforming to a wall shape in which the second defining wall 2421 of the second chamber 242 and the wall portion 2441 of the communication chamber 244 are integrated. The atmospheric pressure detection membrane 70 is welded or bonded to the end surface of the cylindrical wall 2422, the end surface of the upper wall 2423, and the end surface of the wall 2441, thereby closing the openings of the second chamber 242 and the communication chamber 244. In addition, the atmospheric pressure detection film 70 is welded or bonded in a state where no tension is particularly applied.

The pump portion 232 is disposed adjacent to the rear of the tank portion 231, and includes a cam shaft insertion hole 322 through which a pump chamber 321 that houses the pump 9 and a cam shaft 93 (fig. 4) that pivotally supports an eccentric cam 91 of the pump 9 are inserted. The opening on the right side of the pump chamber 321 is closed by a pump cover 323.

[ negative pressure supply mechanism of second embodiment ]

The liquid supply unit 3A according to the second embodiment also includes a negative pressure supply mechanism that supplies ink from the first chamber 241 to the second chamber 242 in response to a decrease in ink in the second chamber 242. The basic configuration is the same as that of the first embodiment, but the point is different in that the pushing member 50 has a configuration for pushing the opening/closing valve 6 by the principle of a lever.

Fig. 38(a) and (B) are perspective views of the pressing member 50 with different directions of view. The pushing member 50 is a member rotatably disposed in the second chamber 242. The pressing member 50 includes: a circular plate portion 251 formed of a circular flat plate; a pair of arm portions 252 extending outward from the upper end side of the disc portion 251; a fulcrum portion 253 provided at an extended distal end portion of each arm portion 252; and a pair of link protrusions 254. The pair of fulcrum portions 253 is pivotally supported by pivot support portions 2426 (fig. 35 and 37) of the pair of support plates 2425 disposed in the second chamber 242. Accordingly, the disk portion 251 is rotatable about the axis of the fulcrum portion 253. The urging member 5 of the first embodiment is rotatably supported on the lower end side, while the urging member 50 of the second embodiment is rotatably supported on the upper end side, which are different in this respect.

The disc portion 251 is a disc having a diameter of about 1/2 degrees with respect to the inner diameter of the cylindrical wall 2422 defining most of the second chamber 242. The cylindrical wall 2422 and the disc portion 251 are arranged substantially concentrically in a state of being pivotally supported by the pivot support portion 2426. The disc portion 251 includes: a first surface 251A facing the atmospheric pressure detection film 70; and a second surface 251B facing the opening/closing valve 6. A spring fitting protrusion 2511 is provided at the radial center of the disk portion 251 so as to protrude from the second surface 251B side. The right end of the biasing spring 245 formed of a coil spring is fitted to the spring fitting protrusion 2511. Further, on the first surface 251A side, the region of the spring fitting protrusion 2511 is a columnar recess.

The disc portion 251 includes: a pressure receiving portion 25A that receives a displacement force from the atmospheric pressure detection film 70; and a biased portion 25B biased by a biasing spring 245. The pressure receiving portion 25A is a region of the peripheral edge portion of the spring fitting protrusion 2511 in the first surface 251A of the disk portion 251. The biased portion 25B is a region of the spring fitting protrusion 2511 in which the biasing spring 245 on the second surface 251B side is fitted. That is, the biased portion 25B is set at a position corresponding to the pressure receiving portion 25A.

When the pressure receiving portion 25A does not receive a displacement force from the atmospheric pressure detection film 70, the disk portion 251 is in a state close to natural hanging. However, the right end of the biasing spring 245 abuts on the biased portion 25B, and the first surface 251A contacts the inner surface of the atmospheric pressure detection film 70. On the other hand, if the pressure receiving portion 25A receives a displacement force equal to or greater than the biasing force of the biasing spring 245 from the atmospheric pressure detection film 70, the disc portion 251 rotates leftward about the axis of the fulcrum portion 253, and changes from a hanging state to a state inclined leftward.

The lower ends 2521 of the pair of arm portions 252 are located on both sides of the spring fitting protrusion 2511, respectively, and the spring fitting protrusion 2511 is sandwiched between the pair of lower ends 2521. The pair of arm portions 252 extend linearly upward from the respective lower end portions 2521. Between the pair of arm portions 252, a cutout 2512 is provided in the radial direction in the disk portion 251. The pair of arm portions 252 extend in parallel from the circular plate portion 251 through the notch portion 2512.

A rectangular thick arm 2522 is provided at the middle of each arm 252 in the vertical direction. The thick arm portion 2522 is disposed near the upper end of the disk portion 251 and on the side of the cutout portion 2512. That is, the pair of thick arms 2522 face each other in the front-rear direction with the notch 2512 interposed therebetween. The fulcrum portions 253 protrude in the front-rear direction from distal end portions 2523 that are the extending ends of the arm portions 252. Specifically, the fulcrum portions 253 protrude forward from the front side surface of the front distal end portion 2523, the fulcrum portions 253 protrude rearward from the rear side surface of the rear distal end portion 2523, and the two fulcrum portions 253 protrude in a direction away from each other. The fulcrum portion 253 is fitted into the pivot support portion 2426 of the support plate 2425. The fulcrum portion 253 is provided at the extended distal end portion 2523 of the arm portion 252, and contributes to an increase in the lever ratio described later.

The pair of fulcrum portions 253 is arranged on the rotation shaft 25AX extending in the front-rear direction. The front fulcrum 253 is disposed at a predetermined distance D from the rear fulcrum 253. That is, the pair of fulcrum portions 253 are disposed apart from each other across a portion corresponding to the central region of the disk portion 251 in the planar direction. The distance D may be set to a dimension of about 40% to 80% of the diameter of the disc portion 251, for example. Accordingly, the pivot points formed by the pair of pivot point portions 253 are wide pivot points separated from each other to sandwich the central region of the disc portion 251. Therefore, the disk portion 251 rotated about the rotation fulcrum is hard to be twisted about an axis perpendicular to the rotation axis 25 AX. Therefore, the rotational operation of the disc portion 251 can be stabilized.

A pair of link protrusions 254 protrude leftward from the second surface 251B near the upper end of the circular plate portion 251. Specifically, link protrusions 254 formed of rectangular flat plates are provided upright from respective end edges of the pair of thick arm portions 2522 facing the cutout portions 2512. Therefore, the pair of link protrusions 254 are located inside the pair of fulcrum portions 253 and in the central region of the disk portion 251. Each link projection 254 is provided with a link hole 2541. The link hole 2541 is used for link coupling of the pushing member 50 and the opening/closing valve 6 shown in the first embodiment. The opening and closing operation of the opening and closing valve 6 is linked with the rotational operation of the pressing member 50 by the link connection.

In other words, the link projection 254 serves as a pressing portion that presses the opening/closing valve 6 to move in the left-right direction in response to the rotational operation of the pressing member 50 that rotates about the axis of the fulcrum portion 253. In the relationship between the pressure receiving portion 25A (force point) and the fulcrum portion 253 (fulcrum), the link projection 254 (action point) is set between the pressure receiving portion 25A and the fulcrum portion 253. That is, the pressure receiving portion 25A, the fulcrum portion 253, and the link projection 254 are set so that the positional relationship of the second type lever is established. Therefore, the displacement force of the atmospheric pressure detection membrane 70 received by the pressure receiving portion 25A can be increased by an amount corresponding to the ratio of the lever ratio, and the pressing force can be applied to the opening/closing valve 6 from the link projection 254.

The operation of the negative pressure supply mechanism of the second embodiment having the pressing member 50 will be described with reference to schematic diagrams of fig. 39(a) and (B). Fig. 39(a) shows a state in which the pressing member 50 (the circular plate portion 251) is in a hanging posture and the opening/closing valve 6 is in a closed posture, and fig. 39(B) shows a state in which the pressing member 50 is in a tilted posture by rotation and the opening/closing valve 6 is in an open posture.

The state of fig. 39(a) is a state in which the atmospheric pressure detection film 70 does not generate a displacement force to such an extent that the disc portion 251 is rotated, that is, a state in which the total of the spring pressure of the urging spring 245 and the internal pressure of the second chamber 242 is greater than the atmospheric pressure. Although the second chamber 242 has a negative pressure, the biasing spring 245 applies a biasing force to the biased portion 25B that is larger than the displacement force of the atmospheric pressure detection film 70 generated based on the negative pressure. Therefore, the disk portion 251 maintains the above-described hanging posture without rotating about the axis of the fulcrum portion 253.

When the degree of negative pressure in the second chamber 242 increases due to the consumption of ink and the second chamber 242 reaches a negative pressure exceeding a predetermined threshold value, the atmospheric pressure detection film 70 applies a pressing force against the biasing force of the biasing spring 245 to the pressure receiving portion 25A of the disk portion 251. That is, the total of the spring pressure of the biasing spring 245 and the internal pressure of the second chamber 242 is lower than the atmospheric pressure. At this time, as shown in fig. 39(B), the disc portion 251 rotates leftward about the axis of the fulcrum portion 253 against the urging force of the urging spring 245. By this rotation, the link projection 254 generates a pressing force that urges the opening/closing valve 6 to the left, and the posture of the opening/closing valve 6 is changed to the open posture.

According to the pressing member 50 of the second embodiment, a large pressing force can be generated in the link protrusion 254 by the force of the lever. Specifically, a link projection 254 that presses the opening/closing valve 6 is disposed between the pressure receiving portion 25A and the fulcrum portion 253. That is, the pressing member 50 realizes the pressing structure of the opening/closing valve 6 by the principle of the lever with the shaft fulcrum of the fulcrum portion 253 as the fulcrum P21, the pressure receiving portion 25A as the force point P22, and the link protrusion 254 as the operating point P23. Therefore, the pressing force applied to the pressure receiving portion 25A by the displacement force of the atmospheric pressure detection membrane 70 can be increased by an amount corresponding to the ratio of the lever ratio and applied to the opening/closing valve 6 from the link projection 254. Therefore, the link projection 254 can be pressed against the opening/closing valve 6 with a large pressing force, and a sufficient pressing force for moving the opening/closing valve 6 at a proper timing can be ensured.

The pressing member 50 includes an arm portion 252 extending upward from the upper end side of the disk portion 251, and a fulcrum portion 253 serving as a rotation fulcrum is provided at an extending distal end portion 2523 of the arm portion 252. This structure makes the distance between the pressure receiving portion 25A (force point P22) and the link protrusion 254 (action point P23) longer, contributing to an increase in the lever ratio. Therefore, the pressing force generated by the pressing member 50 can be further increased.

[ backflow prevention mechanism of second embodiment ]

Next, the backflow prevention mechanism 238 according to the second embodiment will be described with reference to fig. 37 and fig. 40(a) to 42 (B). The backflow prevention mechanism 238 is a mechanism for preventing the pressurized ink from flowing backward into the second chamber 242 when the pressure purge mode is executed. Fig. 37 is an exploded perspective view of the backflow prevention mechanism 238. The backflow prevention mechanism 238 includes a valve pipe 281, a branch head 282, a ball 283, a seal member 284, a coil spring 285, and an O-ring 286. The valve line 281 is a member integrated with the top wall 2442 of the communication chamber 244, and other components are assembled to the valve line 281. Fig. 40(a) and (B) are perspective views of the backflow prevention mechanism 238 excluding the valve line 281, and fig. 40(C) is a perspective view of the branch head 282 as viewed from below.

The valve duct 281 is a duct extending in the up-down direction from the upper surface of the top wall 2442. The valve line 281 is provided to provide an ink flow path connecting the communication chamber 244 and the downstream pipe 234, and constitutes a part of an ink supply path from the second chamber 242 to the ink ejecting section 22 (fig. 5). In order to lock the branch head part 282, a locking piece 2811 is provided on the outer peripheral surface of the valve passage 281, and a fitting annular protrusion 2812 is provided on the inner peripheral surface thereof.

The branch header 282 is a member forming a junction a of the bypass pipe 235 and the downstream pipe 234. The branch head portion 282 includes a first inlet port 2821, a second inlet port 2822, an outlet port 2823, a case portion 2824, a locking window 2825, a notch portion 2826, and a fitting claw 2827. First inlet port 2821 is a port to which the downstream end of second chamber 242 is connected, and in the present embodiment, communicates with second chamber 242 via valve line 281 and communication chamber 244. The second inlet port 2822 is the port to which the downstream end of the bypass tube 235 is connected. The outlet port 2823 is the port to which the upstream end 2341 of the downstream pipe 234 is connected. In the print mode described, ink is supplied to the downstream tube 234 through the first inlet port 2821. On the other hand, in the pressure purge mode, ink is supplied to the downstream pipe 234 through the second inlet port 2822.

The case 2824 is formed of a pair of arcuate pieces arranged to face each other outside the first inlet port 2821 facing downward. The valve line 281 enters a gap between a pair of housing portions 2824 and the first inlet port 2821. The locking windows 2825 are openings provided in the pair of case portions 2824, and are openings through which the locking pieces 2811 of the valve pipe 281 are engaged. The cutout 2826 is a portion in which a part of the peripheral wall of the cylindrical first inlet port 2821 is cut, and is a portion for ensuring a flow path of ink. The fitting claw 2827 is a hook-shaped portion protruding downward from the lower end of the first inlet port 2821, and engages with the fitting annular protrusion 2812 of the valve pipe 281. That is, the branch head part 282 is fixed to the valve pipe passage 281 by engagement of the locking piece 2811 with the locking window 2825 on the inner periphery of the valve pipe passage 281 and engagement of the fitting annular protrusion 2812 with the fitting claw 2827 on the outer periphery.

The ball 283 is accommodated in the valve passage 281 so as to be movable in the ink supply direction, and functions as a valve. The outer diameter of the ball 283 is smaller than the inner diameter of the valve duct 281 and smaller than the inner diameter of the coil spring 285. As a material for forming the ball 283, various materials can be used, but it is preferable to use a material having a specific gravity 2 times or less with respect to the specific gravity of the ink. The ball 283 is buried in the ink in the valve line 281. By making the specific gravity of the ball 283 close to that of the ink, the operating pressure of the ball 283 in the ink supply direction (vertical direction in this case) can be reduced.

Generally, ink used in an ink jet printer is an aqueous liquid having a specific gravity of 1 or a specific gravity close thereto. Therefore, as the material of the ball 283, a material having a specific gravity of < 2 is preferably selected. The material preferably has chemical resistance and abrasion resistance which do not deteriorate even when the material is constantly in contact with ink. From these viewpoints, the polyacetal resin (specific gravity ≈ 1.5) is particularly preferably used as the material of the spherical body 283.

The seal member 284 is a ring-shaped seal element, and is, for example, a seat 2813 disposed on the bottom wall of the valve passage 281 (the upper surface of the top wall 2442) below the ball 283 as shown in fig. 41B. The ring inner diameter (through hole) of the seal member 284 is set smaller than the outer diameter of the ball 283 and larger than the diameter of the supply hole 2443 that penetrates out of the top wall 2442. As shown in fig. 40(a), when the ball 283 is separated from the seal member 284, the valve line 281 is opened. On the other hand, as shown in fig. 40(B), when the ball 283 abuts on the seal member 284, the valve line 281 is closed.

The coil spring 285 is a compression spring installed in the valve duct 281 such that the lower end thereof abuts against the seal member 284 and the upper end thereof abuts against the lower end edge 2828 of the first inlet port 2821 of the branch head 282. The coil spring 285 applies a force to the seal member 284 toward the seat portion 2813, whereby the seal member 284 is always crimped to the seat portion 2813. Further, a ball 283 is housed inside the coil spring 285, and the coil spring 285 also functions to guide the movement of the ball 283 in the ink supply direction. Therefore, the play of the ball 283 in the valve pipe 281 is regulated, and the valve structure established by the contact or separation of the ball 283 with respect to the seal member 284 can be stabilized.

O-ring 286 seals the interface of valve line 281 and branch head 282. The O-ring 286 is fitted to the outer peripheral surface of the first inlet port 2821, and abuts against the protruding base 2829 of the first inlet port 2821.

Fig. 41(a) is a cross-sectional view showing a state of the backflow prevention mechanism 238 in the print mode, and fig. 41(B) is an enlarged view of a portion a4 of fig. 41 (a). Fig. 41(a) shows the pump 9 housed in the pump section 232. The pump 9 has the same structure as that of the first embodiment. In the present embodiment, the extruding pipe 92 is a pipe integrated with the communication pipe 232P and the bypass pipe 235. That is, one end side of the pressing pipe 92 communicates with the bottom wall portion 2413 (communication pipe 232P) of the first chamber 241, the other end side communicates with the second inlet port 2822 (bypass pipe 235) of the branch head portion 282, and the central portion is set as a pressing portion disposed on the circumferential surface of the eccentric cam 91.

The pump 9 is in a stopped state in the printing mode. At this time, the eccentric cam 91 crushes the pressing tube 92 to be in a stopped state, and thus the ink supply passage through the bypass tube 235 is closed. On the other hand, in the pressure purge mode, the pump 9 is driven in the normal rotation. In fig. 41(a), the normal rotation direction of the eccentric cam 91 is the counterclockwise direction. By the normal rotation driving of the pump 9, ink is sucked from the first chamber 241 through the communication pipe 232P, and flows from the bypass pipe 235 toward the backflow prevention mechanism 238 serving as the junction a. Further, if the pump 9 is driven in reverse, the decompression mode is set as shown in fig. 9(B), and the communication chamber 244, the second chamber 242, and the downstream pipe 234 are depressurized through the bypass pipe 235 and the branch head 282.

Next, the operation of the backflow prevention mechanism 238 will be described. In the print mode (first state), ink is supplied from the second chamber 242 to the head unit 21 through a supply path passing through the communication chamber 244, the backflow prevention mechanism 238, and the downstream pipe 234. In this print mode, as shown in fig. 41(B), the ball 283 is separated from the seal member 284 and floats upward. This is because the supply path from the second chamber 242 to the downstream pipe 234 is maintained at negative pressure in the printing mode. In addition, when the ink ejecting section 22 of the head unit 21 sucks the ink present in the supply path every time an ink droplet is ejected, a force in the ink supply direction acts on the ball 283, and the ball 283 floats from the sealing member 284 in the ink liquid.

Since the ball 283 is separated from the sealing member 284, the supply hole 2443 of the communication chamber 244 is opened. On the other hand, the ball 283 may float up to the lower end edge 2828 of the first inlet port 2821 by the suction force of the ink ejecting section 22. Fig. 40(a) shows a state where the sphere 283 floats to the uppermost position. In this case, since the cutout 2826 is provided in the peripheral wall of the first inlet port 2821, the passage of ink is also ensured. Thus, ink can pass from the communication chamber 244 toward the branch head 282.

Fig. 42(a) is a sectional view showing a state of the backflow prevention mechanism 238 in the pressure purge mode (second state), and fig. 42(B) is an enlarged view of a portion a5 of fig. 42 (a). In the pressure purge mode, ink pressurized by the bypass pipe 235 is supplied to the second inlet port 2822 (junction portion a) of the branch header 282 by the normal rotation driving of the pump 9. Therefore, the bypass pipe 235 and the downstream pipe 234 located on the downstream side of the merging portion a are pressurized by the pressurized ink. At this time, the ink is pressurized to a high pressure exceeding 100 kPa. If such high pressure is applied to the second chamber 242, the atmospheric pressure detection membrane 70 defining a part of the second chamber 242 is sometimes broken or peeled off from the mounting portion of the second defining wall 2421.

However, in the present embodiment, the spherical body 283 is pressed downward (upstream side in the ink supply direction) by the pressing force applied to the merging portion a, and the spherical body 283 abuts on the sealing member 284. Fig. 40(B) and 42(B) show a state in which the ball 283 is fitted into the ring of the seal member 284 by the pressing. The supply hole 2443 is closed by the ball 283 coming into contact with the seal member 284 pressed against the seat portion 2813 by the coil spring 285. That is, in the ink supply path in the print mode, the communication chamber 244 and the second chamber 242 located on the upstream side of the junction a are blocked from the pressurization of the pressurized ink. Therefore, damage and the like of the atmospheric pressure detection membrane 70 can be prevented in advance.

[ modified examples ]

The embodiments of the present invention have been described above, but the present invention is not limited to these embodiments, and for example, the following modified embodiments can be adopted.

(1) In the above embodiment, the

liquid supply units

3 and 3A according to the present invention are exemplified as a method of supplying ink to the head unit 21 of the ink jet printer 1. The liquid stored and supplied in the

liquid supply units

3 and 3A is not limited to ink, and various liquids can be used. For example, water, various solutions, chemical solutions, industrial chemical liquids, and the like can be stored and supplied to the

liquid supply units

3 and 3A.

(2) In the first embodiment, the backflow prevention mechanism 38 using the ball 83 is exemplified, but this is an example, and various backflow prevention structures may be employed. For example, a valve body with a return spring may be disposed in the valve line 81 so as to face the supply hole 42H, and the valve body may block the supply hole 42H when a pressure for pressure removal is applied.

(3) In the above-described embodiment, the opening/closing valve 6 including the umbrella valve 66 is exemplified, but instead, various movable valves may be used as the opening/closing member. For example, in the first embodiment, the pressing member 5 and the opening/closing valve 6 are link-coupled by the link protrusion 54 and the link pin 65, but they may be not link-coupled. For example, a part of the pressing member 5 and a part of the opening/closing valve 6 may be constantly in contact with each other by a spring or the like, and the pressing member 5 may press the opening/closing valve 6 through the contact portion.

(4) For example, in the first embodiment, the pressing member 5 includes the pair of fulcrum portions 53 separated from each other in the rotation axis direction. Alternatively, a single long axis extending in the direction of the rotation axis may be used as the fulcrum 53. Alternatively, in a case where the rotational twisting of the pressing member 5 is not a problem, a member having a fulcrum portion formed at the distal end of one arm is used instead of the pair of arm portions 52 and the pair of fulcrum portions 53 in the above embodiment. The arm portion 52 may be omitted, and the fulcrum portion 53 may be provided near the upper end of the disk portion 51.

(5) In the above-described embodiment, the opening/closing valve 6 shown in fig. 15(a) and (B) is exemplified as the opening/closing member, but a valve having another configuration may be used instead. Fig. 43(a) is a perspective view of the opening/closing valve 6A according to a modification, and fig. 43(B) is an exploded perspective view of the opening/closing valve 6A. The opening/closing valve 6A is formed by an assembly of a valve support 61A and an umbrella valve 66 held by the valve support 61A. The umbrella valve 66 has the same structure as that of the umbrella valve described above with reference to fig. 15(B), and therefore, the description thereof is omitted here.

The valve support 61A includes a first end 1611 located on the first chamber 41 side and a second end 1612 located on the second chamber 42 side in a state of being assembled to the communication port 43. The valve support 61A includes a tube portion 162 on the first end 1611 side, a flat plate portion 163 on the second end 1612 side, an intermediate portion 164 located between the tube portion 162 and the flat plate portion 163, and a link pin 165 disposed on the flat plate portion 163. The umbrella valve 66 is held on the first end 1611 side of the valve support 61A.

The cylindrical portion 162 is a cylindrical portion having a through hole 166 at the radial center, and a pin portion 662 of the umbrella valve 66 is inserted through the through hole 166. The through hole 166 has an inner diameter smaller than the diameter of the locking ball 663 of the umbrella valve 66, but the pin 662 is inserted into the through hole 166 from the first end 1611 by rubber elasticity so that the locking ball 663 is pressed in and passes through. A plurality of flow path grooves 167 recessed in the radial direction are provided at equal intervals in the circumferential direction on the outer circumferential surface of the cylindrical portion 162. The channel groove 167 is a channel through which ink flows when the opening/closing valve 6A is in the open position.

The intermediate portion 164 is a flat plate portion having substantially the same width as the outer diameter of the tube portion 162 and wider than the flat plate portion 163. A pin receiving portion 168 formed by a cutout that receives the pin portion 662 is provided in a portion from the intermediate portion 164 to the flat plate portion 163. The cylindrical portion 162 and the intermediate portion 164 are accommodated in the large diameter portion 43A of the communication port 43. When the opening/closing valve 6A moves in the left-right direction, the outer peripheral surfaces of the cylindrical portion 162 and the intermediate portion 164 become the guide surface 162S guided by the large diameter portion 43A. At the boundary between the flat plate portion 163 and the intermediate portion 164, there is an abutting portion 164A formed by a step based on the difference in width between the two. The contact portion 164A faces and contacts the step portion 43C (fig. 17B) of the communication port 43. The link pin 165 protruding from the flat plate portion 163 is fitted into a link hole 541 (fig. 14B) provided in the link projection 54 of the pressing member 5.

In the opening/closing valve 6A, when in the closed position, the communication port 43 is closed when the sealing surface 67 of the umbrella valve 66 abuts against the sealing wall surface 43S (fig. 16B). On the other hand, when the ink container is in the open position, the seal surface 67 is separated from the seal wall surface 43S, and ink flows through the flow channel 167. Note that when excessive internal pressure acts on the second chamber 42, the point at which the umbrella shape of the umbrella portion 661 reverses is the same as that described with reference to fig. 29(a) and (B). The opening/closing valve 6A as described above can also function as an opening/closing member.

Claims

1. A liquid supply unit that supplies a liquid from a liquid storage container storing a specified liquid to a liquid ejecting head that ejects the liquid, comprising:

a pressure chamber capable of storing the liquid;

a first supply passage that communicates the liquid accommodating container with the pressure chamber;

a second supply passage that communicates the liquid ejection head with the pressure chamber;

a bypass supply passage including one end connected to the first supply passage and the other end connected to the second supply passage and including a pipe line directly connecting the first supply passage and the second supply passage without passing through the pressure chamber; and

a pressurizing mechanism that is disposed in the bypass supply passage and pressurizes the liquid flowing through the bypass supply passage, the pressurizing mechanism supplying the liquid from the first supply passage to the second supply passage with the one end as an upstream end in a liquid supply direction in the bypass supply passage and the other end as a downstream end,

the liquid supply unit is characterized in that,

the second supply passage has a start end portion connected to the pressure chamber,

the liquid supply unit further includes a reverse flow prevention mechanism, disposed in the second supply passage between a junction of the second supply passage and the other end of the bypass supply passage and the start end portion, that prevents the liquid pressurized by the pressurization mechanism from flowing backward toward the pressure chamber.

2. The liquid supply unit according to claim 1,

the pressure chamber, the backflow prevention mechanism, and the second supply passage are arranged in an up-down direction such that: the backflow prevention mechanism is located below the pressure chamber, and the merging portion is located below the backflow prevention mechanism.

3. A liquid supply unit that supplies a liquid from a liquid storage container storing a specified liquid to a liquid ejecting head that ejects the liquid, comprising:

a pressure chamber capable of storing the liquid;

the liquid supply unit is characterized in that,

a portion of the wall bounding the pressure chamber is formed by a flexible membrane member.

4. The liquid supply unit according to claim 2, wherein the reverse flow prevention mechanism comprises:

a valve pipe extending in an up-down direction and constituting a part of the second supply passage;

a ball housed in the valve pipe so as to be movable in the liquid supply direction; and

a sealing member disposed at an upper end of the valve pipe, closing the valve pipe when the ball abuts against the sealing member, and opening the valve pipe when the ball is separated from the sealing member by movement in the liquid supply direction,

the ball is moved down by its own weight in the valve pipe so as to be separated from the seal member in a first state in which the liquid is supplied from the pressure chamber to the liquid ejecting head, and is moved up by the pressure in the valve pipe so as to come into contact with the seal member in a second state in which the pressurized liquid is supplied to the liquid ejecting head through the bypass supply path.

5. Liquid supply unit according to claim 4,

the pressure chamber has a liquid discharge port at the lowermost end portion thereof,

the valve line is a line extending vertically downward from the liquid discharge port, and includes a seat portion on an upper end side thereof for seating the seal member, and a ball receiving portion on a lower end side thereof for receiving the ball in the first state and having a notch portion serving as a liquid flow path,

the pipe line constituting the other part of the second supply passage includes a vertical portion extending vertically downward from the lower end side of the valve pipe line,

the downstream end of the bypass supply passage merges with the depending portion.

6. The liquid supply unit according to claim 1, wherein the reverse flow prevention mechanism comprises:

a valve line constituting a part of the second supply passage;

a sealing member that closes the valve conduit when the ball abuts against the sealing member and opens the valve conduit when the ball is separated from the sealing member by movement in the liquid supply direction, wherein,

the ball is separated from the seal member in a first state in which the liquid is supplied from the pressure chamber to the liquid ejecting head, and abuts against the seal member in a second state in which the pressurized liquid is supplied to the liquid ejecting head through the bypass supply passage.

7. Liquid supply unit according to claim 6,

wherein the liquid supply unit is configured such that the liquid storage container is disposed above and the liquid ejecting head is disposed below, and the liquid supply unit supplies the liquid from the liquid storage container to the liquid ejecting head by a head difference,

in the first state, the pressure chamber and the second supply passage are maintained at a negative pressure,

in the second state, the bypass supply passage and the second supply passage on the downstream side of the confluence portion are pressurized by the pressurized liquid,

the ball is separated from the seal member by the negative pressure in the first state, and is brought into contact with the seal member by the pressurization in the second state.

8. Liquid supply unit according to claim 6,

the sealing member has a ring shape having a through hole with a diameter smaller than the outer diameter of the ball,

the valve line includes a seat portion for seating the seal member,

the backflow prevention mechanism further includes a coil spring that is attached to the valve pipe, applies a force to the seal member toward the seat portion, and guides movement of the ball in the liquid supply direction.

9. Liquid supply unit according to claim 4,

the specific gravity of the sphere is set in a range of 1.1 to 1.5 times the specific gravity of the liquid.

10. Liquid supply unit according to claim 6,

the valve pipe is a pipe extending in the up-down direction,

the specific gravity of the sphere is set to 2 times or less of the specific gravity of the liquid.

11. The liquid supply unit according to claim 3, characterized by further comprising:

an upstream chamber that constitutes a part of the first supply passage and is disposed on an upstream side in a liquid supply direction with respect to the pressure chamber;

a wall portion provided with a communication port that communicates the upstream chamber with the pressure chamber;

an opening/closing member that is disposed in the communication port and changes a posture between a closed posture in which the communication port is closed and an open posture in which the communication port is opened;

a biasing member that biases the opening/closing member in a direction toward the closed position; and

a pressing member capable of pressing the opening/closing member in the direction of the open posture,

the flexible film member is a member that is displaced based on negative pressure generated in association with a decrease in liquid in the pressure chamber and transmits the displacement force thereof to the pushing member,

the pushing member has: a pressure receiving portion that receives a displacement force from the flexible film member; and a pushing portion that pushes the opening/closing member against the urging force of the urging member by using the displacement force received by the pressure receiving portion.

12. The liquid supply unit according to claim 1,

in a first state in which the liquid is supplied from the pressure chamber to the liquid ejection head, the pressure chamber and the second supply channel are maintained at a negative pressure,

in a second state in which the pressurized liquid is supplied to the liquid ejection head through the bypass supply channel, the bypass supply channel and the second supply channel on the downstream side of the merging portion are pressurized by the pressurized liquid, and the second supply channel and the pressure chamber on the upstream side of the merging portion are blocked from the pressurization by the backflow prevention mechanism.

13. The liquid supply unit according to any one of claims 1 to 12, further comprising:

and an exhaust mechanism that exhausts air from the pressure chamber.

14. The liquid supply unit according to any one of claims 1 to 12,

the pressurizing mechanism is a pump mounted on the liquid supply unit.

15. A liquid ejection apparatus characterized by comprising:

a liquid ejecting head that ejects a specified liquid; and

the liquid supply unit according to any one of claims 1 to 14, wherein the liquid is supplied from a liquid storage container storing the liquid to the liquid ejection head.