JP2011196207A - Diaphragm liquid supply pump and inkjet printer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a diaphragm liquid supply pump which can control excessive displacement of a diaphragm in a direction where volume of a pump chamber decreases, without lowering circulation of liquid and discharge of air bubbles.SOLUTION: The pump chamber 47 of the diaphragm liquid supply pump 40 is defined by a circular inner peripheral side 43a, a bottom 43b of the pump chamber, and the diaphragm 46 displaced to increase and decrease the volume of the pump chamber. A plurality of projections 52 with the same height are formed from the bottom 43b of the pump chamber. The projections 52 are each arranged apart from each other, and a communicating passage part 53 going through the projections 52 is formed between the diaphragm 46 and the bottom 43b of the pump chamber, in a state that the diaphragm 46 abuts on the projections 52. The projections 52 allow the excessive displacement of the diaphragm 46 to be prevented without inhibiting the circulation of the liquid and the discharge of the air bubbles.

Description

  The present invention relates to a diaphragm-type liquid supply pump that performs a liquid suction and supply (discharge) operation by displacing a diaphragm defining a part of a pump chamber to increase or decrease the volume of the pump chamber.

  The ink supply system of the ink jet printer includes a main tank such as an ink cartridge mounted on the printer main body and a sub tank mounted on the carriage together with the ink jet head. When performing printing, ink is supplied from the sub tank to the ink jet head. Is supplied and ink is replenished from the main tank to the sub-tank at the time of printing standby when the inkjet head is stopped at the home position. Ink supply from the sub-tamp to the inkjet head is performed by negative pressure on the inkjet head side, and ink replenishment operation to the sub-tank is performed by pump driving. Such ink supply systems are described in Patent Documents 1 to 3.

  On the other hand, as a liquid supply pump, as disclosed in Patent Documents 4 and 5, a diaphragm pump is known. When a diaphragm type liquid supply pump is used, a pump chamber whose volume is increased or decreased by the displacement of the diaphragm is used as a sub tank, and the ink is supplied by displacing the diaphragm by the negative pressure (back pressure) on the ink jet head side. When ink is replenished, the diaphragm may be forcibly displaced by a cam or the like as described in Patent Document 4 to increase the pump chamber volume and reinforce the ink from the main tank to the pump chamber.

  Here, in the diaphragm pump described in Patent Document 5, in order to prevent excessive deformation of the diaphragm, a deformation amount suppressing member for restricting the maximum deformation amount of the diaphragm is provided on the atmospheric pressure side. The deformation amount suppressing member has a flat surface that faces the diaphragm, hits the surface of the diaphragm as a whole, and restricts the displacement of the diaphragm to the atmosphere.

JP 2005-59490 A JP 2006-289736 A Japanese Patent No. 4051894 JP 2006-161648 A JP 2008-101495 A

  When a diaphragm-type liquid supply pump is used as a sub tank and an ink pump of an ink jet printer, the negative pressure acting from the ink jet head side causes the diaphragm to be displaced and the pump chamber volume (sub tank volume) to decrease, so that the ink is transferred to the ink jet head. Supplied to the side. When a large negative pressure is applied, the diaphragm may be excessively displaced. For example, in a cleaning operation in which ink droplets are simultaneously ejected from each nozzle of an inkjet head to prevent nozzle clogging or the like, there is a possibility that a large negative pressure acts and the diaphragm is greatly displaced. Therefore, it is not possible to prevent the harmful effects caused by the excessive displacement of the diaphragm by simply arranging the displacement amount suppressing member on the atmosphere side as in Patent Document 5 and controlling the displacement amount in the direction in which the pump volume increases.

  In addition, when the flat displacement amount suppressing member described in Patent Document 5 is arranged in a pump chamber in which liquid such as ink is stored, ink flowability is hindered and mixed in ink or the like. Bubbles are likely to remain in the pump chamber, and the bubble discharge performance is also reduced. As a result, the ink supply amount varies and the print quality may be deteriorated. In addition, the residual bubbles in the pump chamber increase, and the bubbles move toward the ink jet head during printing, making it difficult for ink droplets to be discharged and causing defective discharge, which may also reduce print quality.

  In view of these points, the present invention has made it possible to control the excessive displacement of the diaphragm in the direction of decreasing the pump chamber volume without causing adverse effects such as a decrease in liquid flowability and bubble discharge performance. It is to propose a diaphragm type liquid supply pump and an ink jet printer provided with the liquid supply pump.

In order to solve the above problems, the diaphragm-type liquid supply pump of the present invention includes:
A pump room,
The bottom of the pump chamber sealing one end of the pump chamber in the direction of its central axis,
The other end of the pump chamber in the direction of the central axis is sealed, and a diaphragm that is displaced in the direction of the central axis to increase or decrease the volume of the pump chamber;
A liquid suction port and a liquid discharge port formed on the bottom surface of the pump chamber;
A plurality of protrusions of the same height protruding in the direction of the central axis from the bottom of the pump chamber,
Each of the protrusions is discretely arranged, and in a state where the diaphragm is in contact with the protrusion, the liquid suction port and the liquid discharge port are interposed between the diaphragm and the bottom of the pump chamber via the protrusion. A communication path portion communicating between the outlets is formed.

  In the present invention, protrusions having the same height are formed on the bottom surface of the pump chamber in a discrete manner. The height of the protrusion may be set based on the allowable displacement amount of the diaphragm toward the bottom surface of the pump chamber. By these protrusions, the displacement position of the diaphragm, in other words, the bottom dead center, is defined, and it is possible to prevent the life of the diaphragm from being reduced due to the excessive displacement of the diaphragm. Further, in the state where the diaphragm hits the protrusion, a communication passage portion that passes between the protrusions remains between the diaphragm and the bottom surface of the pump, so that it is possible to ensure the fluidity of the liquid. Further, since the bubbles mixed in the liquid and entering the pump chamber easily move between the projections, even if the projections are provided, the bubble discharging performance from the pump chamber does not deteriorate.

  Here, each of the protrusions is a protrusion having the same shape, and is preferably arranged at a line-symmetrical or point-symmetrical position with respect to the center of the bottom surface of the pump chamber. In this way, the liquid flows evenly on the entire bottom surface of the pump chamber, so that it is possible to prevent adverse effects such as the liquid remaining in a part and the bubbles being accumulated. In addition, since the projections are in contact with the diaphragm in a line-symmetrical or point-symmetrical state, the deformation of the diaphragm can be uniformly suppressed as a whole, and a local excessively deformed portion is not formed on the diaphragm.

  Further, four protrusions are formed on the bottom surface of the pump chamber, and each of the protrusions is a cylindrical protrusion having the same shape, and an angle of 90 degrees on the same circle centering on the center of the bottom surface of the pump chamber. It is desirable to arrange them at intervals. If it does in this way, displacement of each part of a diaphragm will be controlled equally in each part, and smooth fluid circulation nature in a pump chamber bottom part can be secured.

Next, the liquid supply pump of the present invention has the above-described configuration,
A piston arranged coaxially with respect to the pump chamber, and a piston movable in the direction of the central axis of the pump chamber;
A biasing member that biases the piston in a direction away from the bottom surface of the pump chamber;
An operating lever coupled to the piston via the biasing member;
A center portion of the diaphragm is fitted and fixed to a tip portion of the piston on the bottom side of the pump.

  In the liquid supply pump having this structure, the diaphragm can be displaced in the direction of increasing the pump chamber volume by operating the operation lever, and the liquid can be replenished in the pump chamber. When the operation lever is in a free state and the liquid in the pump chamber is reduced, the diaphragm is gradually displaced toward the bottom of the pump chamber. If the diaphragm is excessively displaced on the bottom side of the pump chamber, the central portion of the diaphragm that is fitted and fixed to the piston may be disengaged from the piston. According to the present invention, excessive protrusion of the diaphragm is prevented by the protrusion, so that it is possible to surely prevent adverse effects such as the diaphragm being detached from the piston and not functioning.

  Next, the ink jet printer of the present invention has a diaphragm type ink supply pump inserted in an ink supply path for supplying ink from an ink tank to the ink jet head, and the ink supply pump is a diaphragm type liquid having the above-described configuration. A supply pump, wherein the liquid suction port communicates with the ink tank side, and the liquid ejection port communicates with the inkjet head.

  In the ink supply pump of the present invention, the maximum displacement of the diaphragm toward the pump volume decreasing side is limited by a plurality of protrusions arranged in the pump chamber. Therefore, it is possible to suppress variations in the ink supply amount due to the negative pressure fluctuation on the ink jet head side, and it is possible to stabilize the printing quality. In addition, since the ink supply amount varies greatly due to the excessive displacement of the diaphragm when the inkjet head is cleaned, it is possible to prevent excessive ink consumption during the cleaning. Furthermore, since the excessive displacement of the diaphragm is suppressed, it is possible to prevent the life of the diaphragm from being shortened.

  The diaphragm-type liquid supply pump of the present invention employs a configuration in which a plurality of protrusions having the same height are arranged discretely on the bottom surface of the pump chamber, thus obstructing the liquid flowability and bubble discharge performance of the bottom portion of the pump chamber. Without excessive displacement of the diaphragm to the pump chamber bottom surface side can be suppressed.

It is explanatory drawing which shows the liquid supply system provided with the diaphragm-type liquid supply pump. It is operation | movement explanatory drawing of the liquid supply pump of FIG. It is explanatory drawing which shows the protrusion formed in the pump chamber bottom face of the liquid supply pump of FIG. 1 is an external perspective view of an ink jet printer to which the present invention is applied. It is a schematic perspective view of a printer mechanism part. It is a perspective view of a carriage and an ink supply system. It is explanatory drawing which shows schematic structure of the ink supply system of an inkjet printer.

  A diaphragm type liquid supply pump and an ink jet printer to which the present invention is applied will be described below with reference to the drawings.

[Diaphragm type liquid supply pump]
FIG. 1 is a schematic configuration diagram showing a liquid supply system including a diaphragm type liquid supply pump according to the present embodiment. 2A, 2B, and 2C are schematic cross-sectional views showing the liquid supply pump, respectively, and show a case where the liquid supply pump is cut along a cross section orthogonal to the case of FIG. First, as shown in FIG. 1, the liquid supply system 30 includes a diaphragm-type liquid supply pump 40 and liquids connected to a liquid suction port 41 and a liquid supply port (liquid discharge port) 42 of the liquid supply pump 40. A replenishment path 31 and a liquid supply path 32 are provided. A liquid main tank 33 is connected to the other end of the liquid supply path 31, and the liquid is sucked (supplemented) into the liquid supply pump 40 from here. A liquid consuming device 34 is connected to the other end of the liquid supply path 32, and a liquid is supplied from a liquid supply pump 40. The liquid supply pump 40 is provided with a drive mechanism 35 for driving the liquid supply pump 40.

  As shown in FIGS. 1 and 2, the liquid supply pump 40 includes a cylindrical pump case 43 with a bottom, and a cylindrical guide cylinder 44 attached coaxially to the open end of the pump case 43. Yes. A diaphragm 46 is disposed at the opening end of the pump case 43 so as to seal the opening end. The diaphragm 46 includes a thick central portion 46a, a thin portion 46b integrally formed so as to surround the central portion 46a, and an outer peripheral rim portion having a predetermined thickness integrally formed so as to surround the outer peripheral edge of the thin portion 46b. 46c. An outer peripheral rim portion 46c of the diaphragm 46 is sandwiched between the pump case 43 and the guide cylinder 44 in a liquid-tight state. A pump chamber 47 is formed by the circular inner peripheral side surface 43 a and the flat circular pump chamber bottom surface 43 b of the pump case 43 and the diaphragm 46. A central portion 46a of the diaphragm 46 is a circular tip surface 46d having a flat surface facing the pump chamber bottom surface 43b.

  A fitting protrusion 46e that protrudes coaxially is formed at a portion of the central portion 46a of the diaphragm 46 opposite to the pump chamber bottom surface 43b. The fitting protrusion 46e is fitted and fixed in a fitting hole 48a formed at the lower end of the piston 48 that can slide along the guide tube 44 in the direction of the pump chamber central axis 40a (vertical direction). In the piston 48, a spring hook 48b is formed at an upper portion of the fitting hole 48a, and a lower end of a tension coil spring 49 is hung thereon.

  The upper end of the tension coil spring 49 is hung on one end of the operation lever 50. The operation lever 50 is supported so as to be swingable in the vertical direction about a support shaft 50 a attached to the upper end of the guide tube 44. The operation lever 50 is a connection side arm 50b extending in the direction of the pump chamber central axis 40a from the support shaft 50a, and an operation extending from the support shaft 50a to the connection side arm 50b at a substantially right angle and extending downward. Side arm portion 50c. The distal end of the connecting side arm portion 50b is a spring hook, and the upper end of the tension coil spring 49 is hung on this end. The distal end of the operation side arm 50c is bent at a right angle.

  The drive mechanism 35 includes a drive piece 35a for forcibly swinging the tip 50d of the operation side arm 50c of the operation lever 50 in the direction of arrow A. The drive piece 35a can be driven by a drive motor (not shown) or the like. Alternatively, the drive mechanism 35 includes a drive source that holds the drive piece 35a in a fixed position and moves the liquid supply pump 40 side to the drive piece 35a as a whole, and the operation side arm 50c of the operation lever 50 is provided. The operation lever 50 can be forced to swing in the direction of arrow A by pressing against the drive piece 35a.

  When the operation lever 50 is forcibly swung, the piston 48 connected thereto moves upward along the guide cylinder 44, and the diaphragm 46 connected to the piston 48 is also displaced upward. As a result, the volume of the pump chamber 47 is increased, the pump chamber is in a negative pressure state, and the liquid is supplied into the pump chamber 47 from the liquid suction port 41. A check valve 51 is attached to the liquid supply port 42 to prevent the backflow of liquid from the liquid supply port 42 into the pump chamber 47 during liquid replenishment.

  On the other hand, when supplying the liquid, the operation lever 50 is held in a swingable state. In this state, when the liquid is consumed in the liquid consuming device 34 connected to the tip of the liquid supply path 32, the liquid supply path 32 is in a negative pressure state, and the liquid stored in the pump chamber 47 is supplied with the liquid. The liquid is supplied from the port 42 through the check valve 51. When the liquid in the pump chamber 47 decreases, the diaphragm 46 is displaced downward accordingly, and the volume of the pump chamber 47 decreases corresponding to the liquid decrease.

  Here, FIG. 3 is an explanatory view showing the pump chamber bottom surface 43b. Four protrusions 52 are integrally formed on the pump chamber bottom surface 43b. Each protrusion 52 has the same shape and the same height, and is a cylindrical protrusion in this example, and its upper end surface 52a is a circular flat surface orthogonal to the central axis 40a. The four protrusions 52 are arranged on the same circle at an angular interval of 90 degrees with the center of the pump chamber bottom surface 43b as the center, and are located away from each other. A liquid suction port 41 and a liquid supply port 42 are formed at an angular interval of approximately 180 degrees on the outer peripheral edge portion of the pump chamber bottom surface 43b. Since the four protrusions 52 are discretely arranged, even when the flat front end face 46d of the central portion 46a of the diaphragm 46 is pressed against these upper end faces 52a, the gap between the liquid suction port 41 and the liquid supply port 42 is increased. A state in which the communication path portion 53 that connects the two remains is formed. Further, the communication passage portion 54 remains between the circular inner peripheral side surface 43 a of the pump chamber 47 and the protrusion 52.

  As described above, the liquid supply pump 40 having this configuration operates in the operating lever 50 to fill the liquid W from the liquid main tank 33 side, as shown in FIG. The diaphragm 46 is located at a position away from the pump chamber bottom surface 43b. When the liquid is supplied and consumed in this state, the diaphragm 46 is gradually displaced downward as shown in FIG. If the diaphragm 46 is displaced to the vicinity of the pump chamber bottom surface 43b, it will hit the upper end surface 52a of the four protrusions 52 formed in FIG. 2 (c), and further downward displacement is limited. Accordingly, the protrusion 52 defines the bottom dead center of the diaphragm 46 and restricts the maximum amount of displacement of the diaphragm 46 downward.

  Therefore, excessive displacement of the diaphragm 46 can be suppressed by the protrusion 52. In addition, since the flat front end surface 46d of the diaphragm 46 is evenly supported by the flat front end surfaces 52a of the four protrusions 52, excessive deformation of the diaphragm 46 is suppressed, and the fitting protrusion 46e due to excessive displacement of the diaphragm 46 is suppressed. Does not come off the piston 48 side. Further, the four protrusions 52 are discretely arranged at point-symmetric positions on the pump chamber bottom surface 43b, and the communication path portion 53 remains between them. Accordingly, the liquid W does not stay in the pump chamber 47, and bubbles that enter the pump chamber 47 do not remain in the liquid W staying portion.

  In this example, four protrusions 52 are formed. However, for example, it is possible to arrange three protrusions at an angular interval of 120 degrees around the center of the pump chamber bottom surface 43b. Further, the projection may be a rectangular cross section or a polygonal cross section, not a cylindrical one, but a cross section having a nearly circular shape is desirable in order to prevent the liquid flow from staying.

[inkjet printer]
Next, an embodiment of an ink jet printer that uses the liquid supply pump having the above configuration as an ink supply pump will be described.

(overall structure)
FIG. 4 is an external perspective view of the ink jet printer. The ink jet printer 1 performs color printing on a long recording paper fed out from roll paper using a plurality of types of color inks, and includes a printer case 2 having a rectangular parallelepiped shape as a whole. An opening 3 for mounting a roll paper is formed in the front central portion. The opening 3 is sealed by an opening / closing lid 5 to which a recording paper discharge guide 4 is attached at the upper end. A recording paper discharge port 6 is formed between the recording paper discharge guide 4 and the upper edge portion of the opening 3 of the printer case 2. When the lock (not shown) is released and a finger is placed on the recording paper discharge guide 4 and pulled forward, the opening / closing lid 5 can be opened from the closed position shown in the drawing to the open position that falls forward about the lower end.

  A power switch 7a, a paper feed switch 7b, a plurality of operation state display lamps 7c, and the like are arranged on the right side of the opening / closing lid 5 on the front surface of the printer case 2. A mounting port 8 a of an ink cartridge mounting portion 8 having a vertically long rectangular cross section extending in the front-rear direction of the printer is opened on the left side portion of the opening / closing lid 5 on the front surface of the printer case 2. Is installed. When a button (not shown) is operated, the lock is released, the ink cartridge 9 is pushed forward by the spring force, and the ink cartridge 9 can be pulled out.

  FIG. 5 is a schematic perspective view showing the printer mechanism portion covered with the printer case 2 in the inkjet printer 1. As shown in this figure, a roll paper storage unit 11 is formed in the center of the printer mechanism unit 10. When the opening / closing lid 5 is opened, the roll paper storage unit 11 opens forward, and the roll paper is replaced. And so on. On the upper side of the roll paper storage unit 11, a platen 12 that defines a printing area C is bridged in the printer width direction.

  On the upper side of the platen 12, a carriage 14 on which an inkjet head 13 with the nozzle surface facing downward is mounted. A carriage guide shaft 14a spans the rear side of the carriage 14 in parallel with the platen 12 in the printer width direction, and a carriage motor 14b is disposed on the rear side of the carriage guide shaft 14a. The carriage motor 14b is a drive source of a carriage drive mechanism 15 that drives the carriage 14 to reciprocate in the carriage scanning direction along the carriage guide shaft. The carriage 14 is moved from the home position A (position shown by a solid line in FIG. 5 and the position shown in FIG. 3) to the right from the printing area C by the carriage drive mechanism 15 and to the left end position B (FIG. 5) from the platen 12 to the left. The position is reciprocated up to a position indicated by a two-dot chain line in FIG. Upon receipt of the print command, the inkjet printer 1 transports the recording paper fed out from the roll paper by a recording paper transport mechanism (not shown) along the surface of the platen 12 while scanning the carriage 14 in conjunction with this transport operation. Printing on the recording paper is performed by ejecting ink from the inkjet head 13 toward the recording paper.

  A head maintenance unit 16 is disposed at a position off the right side of the platen 12. The inkjet head 13 mounted on the carriage 14 performs flushing, which is an ink droplet ejection operation that is not involved in printing for maintaining and recovering nozzles, at the home position A shown in FIG. 5 facing the head maintenance unit 16. Maintenance operation such as ink suction operation from each ink nozzle is performed. The waste ink liquid discharged from the inkjet head 13 is collected from the head maintenance unit 16 to the side of the ink cartridge 9 attached to the ink cartridge attachment part 8 via a waste ink liquid recovery path (not shown). The head maintenance unit 16 capping the nozzle surface of the inkjet head 13 after flushing and collects the discharged waste ink. During nozzle cleaning, the suction pump is driven with the nozzle surface of the inkjet head 13 capped, and ink is forcibly sucked and discharged from each nozzle by the negative pressure from the suction pump.

(Ink supply system)
FIG. 6 is a perspective view showing only a carriage and an ink supply system in the printer mechanism of the ink jet printer, and FIG. 7 is an explanatory diagram showing a schematic configuration of the ink supply system of the ink jet printer.

  As shown in FIGS. 6 and 7, the carriage 14 is mounted with sub-tanks 17 a to 17 d that store ink of four colors, cyan, magenta, yellow, and black, together with the inkjet head 13. One end of each flexible ink tube 18a to 18d is connected to each of the sub tanks 17a to 17d, and the other end of each of these flexible ink tubes 18a to 18d is at a position on the rear end side of the ink cartridge mounting portion 8. The ink packs (main tanks) 9a to 9d in the ink cartridge 9 are connected to the arranged planar flow channels 19a to 19d. A check valve 24 is provided at the end of the planar flow passages 19a to 19d on the ink cartridge 9 side so that ink flows only in one direction from the ink cartridge 9 toward the sub tanks 17a to 17d. .

  The carriage 14 is equipped with four sets of ink supply pumps 20 for supplying ink from the ink cartridge 9 to the sub tanks 17a to 17d via the flexible ink tubes 18a to 18d. Each pump unit 20 has the same structure as the liquid supply pump 40 described above, and the pump chambers 47 of the liquid supply pumps 40 function as sub tanks 17a to 17d, respectively. A check valve 22 is provided in a flow path portion connecting the sub tanks 17a to 17d and the in-head flow paths 13a to 13d of the inkjet head 13, and only in one direction from the sub tanks 17a to 17d toward the inkjet head 13 side. The ink is configured to flow. The ink in the ink packs 9 a to 9 d is once supplied to the sub tanks 17 a to 17 d by the pump unit 20 and then supplied to the inkjet head 13.

  The ink cartridge 9 has a flat rectangular parallelepiped shape that is long in the front-rear direction and the up-down direction, and four types of ink packs 9a to 9d of cyan, magenta, yellow, and black are arranged in this order from the bottom to the top. Are stored side by side. The ink packs 9a to 9d are sealed in a state where ink is stored in a variable capacity bag made of a flexible material. When the ink cartridge 9 is inserted into the mounting position of the ink cartridge mounting portion 8, the ink pack 9a-9d is provided at the mounting position. The ink supply needles thus inserted are inserted into the ink supply ports of the ink packs 9a to 9d. Thereby, an ink supply path for supplying each color ink from the ink packs 9a to 9d of the ink cartridge 9 to the inkjet head 13 side through each ink supply needle is formed.

  The operation of the pump unit 20 will be described. Since the pump unit 20 has the same configuration as the liquid supply pump 40 shown in FIGS. 1 to 3, in the following description, corresponding parts will be described using parts in the liquid supply pump 40. First, when the carriage 14 is away from the home position A and the inkjet head 13 is located in the printing area C, ink is supplied from the sub tank 17a to the inkjet head 13. That is, the inkjet head 13 performs printing while consuming the ink in the sub tank 17a. Here, when the ink in the sub tank 17a decreases, the capacity of the sub tank 17a decreases due to the negative pressure generated by the decrease in the ink. Along with this, the connecting arm portion 50b connected to the diaphragm 46 in the operation lever 50 is lowered, and as a result, the protruding amount of the connecting arm portion 50c on the home position A side is increased.

  When the carriage 14 moves from the printing area C to the home position A at the end of printing, the operation lever 50 is pressed and shaken by the inner wall surface of the printer case 2 (the part corresponding to the drive piece 35a of the drive mechanism 35 in FIG. 1). Move. Along with this, the tension coil spring 49 is extended, and the diaphragm 46 is pulled upward by the elastic return force of the tension coil spring 49. As a result, the capacity of the sub tank 17a (pump chamber 47) increases and a negative pressure is formed in the sub tank 17a. Further, while the carriage 14 is stopped at the home position A, the elastic restoring force is continuously applied and the capacity increase state of the sub tank 17a is maintained, so that the sub tanks 17a to 17a are connected to the flexible ink tubes 18a to 18d. Ink is replenished in 17d.

  In the inkjet printer 1 according to the present embodiment, the plurality of protrusions 52 arranged in the sub tanks 17a to 17d (pump chamber 47) limit the maximum displacement of the diaphragm 46 toward the tank volume decreasing side. Is done. Therefore, it is possible to suppress variations in the ink supply amount due to the negative pressure fluctuation on the ink jet head 13 (liquid consuming device 34) side, and to stabilize the printing quality. In addition, since the ink supply amount can be prevented from greatly varying due to excessive displacement of the diaphragm 46 when the inkjet head 13 is cleaned, it is possible to prevent excessive ink consumption during cleaning. Furthermore, since the excessive displacement of the diaphragm 46 is suppressed, the lifetime of the diaphragm 46 can be prevented from being reduced.

DESCRIPTION OF SYMBOLS 1 Inkjet printer, 2 Printer case, 3 Opening part, 4 Recording paper discharge guide, 5 Opening / closing lid, 6 Recording paper discharge port, 7a Power switch, 7b switch, 7c Operation status display lamp, 8 Ink cartridge mounting part, 8a mounting port , 9 Ink cartridge, 9a to 9d Ink pack, 10 Printer mechanism, 11 Roll paper storage, 12 Platen, 13 Inkjet head, 13a to 13d Flow path in head, 14 Carriage, 14a Carriage guide shaft, 14b Carriage motor, 15 Carriage drive mechanism, 16 head maintenance unit, 17a to 17d sub tank, 18a to 18d flexible ink tube, 19a to 19d plane flow path, 20 pump unit, 22 check valve, 24 check valve, 31 liquid supply path, 2 Liquid supply path, 33 Liquid main tank, 34 Liquid consumption device, 35 Drive mechanism, 35a Drive piece, 40 Liquid supply pump, 40a Pump chamber central axis, 41 Liquid suction port, 42 Liquid supply port, 43 Pump case, 43a Circular Inner peripheral side surface, 43b Pump chamber bottom surface, 44 Guide tube, 46 Diaphragm, 46a Center portion, 46b Thin wall portion, 46c Outer rim portion, 46d Tip surface, 46e Insertion protrusion, 47 Pump chamber, 48 Piston, 48a Insertion hole, 48b Spring Hanging, 49 Tension coil spring, 50 Operation lever, 50a Support shaft, 50b Connection side arm, 50c Operation side arm, 50d Tip, 51 Check valve, 52 Protrusion, 52a Upper end surface, 53, 54

Claims (5)

A pump room,
The bottom of the pump chamber sealing one end of the pump chamber in the direction of its central axis,
The other end of the pump chamber in the direction of the central axis is sealed, and a diaphragm that is displaced in the direction of the central axis to increase or decrease the volume of the pump chamber;
A liquid suction port and a liquid discharge port formed on the bottom surface of the pump chamber;
A plurality of protrusions of the same height protruding in the direction of the central axis from the bottom of the pump chamber,
Each of the protrusions is discretely arranged, and in a state where the diaphragm is in contact with the protrusion, the liquid suction port and the liquid discharge port are interposed between the diaphragm and the bottom of the pump chamber via the protrusion. A diaphragm-type liquid supply pump characterized in that a communication passage portion communicating between the outlets is formed. In claim 1,
Each of the projections is a projection having the same shape, and is arranged at a line-symmetrical or point-symmetrical position with respect to the center of the bottom surface of the pump chamber. In claim 1 or 2,
Four protrusions are formed on the bottom of the pump chamber,
Each of the protrusions is a cylindrical protrusion having the same shape, and is arranged at an angular interval of 90 degrees on the same circle centered on the center of the bottom surface of the pump chamber. pump. In any one of claims 1 to 3,
A piston arranged coaxially with respect to the pump chamber, and a piston movable in the direction of the central axis of the pump chamber;
A biasing member that biases the piston in a direction away from the bottom surface of the pump chamber;
An operating lever coupled to the piston via the biasing member;
A diaphragm-type liquid supply pump, wherein a central portion of the diaphragm is fitted and fixed to a tip portion of the piston on the bottom surface side of the pump. A diaphragm type ink supply pump inserted in an ink supply path for supplying ink from an ink tank to an inkjet head;
The ink supply pump is a diaphragm type liquid supply pump according to any one of claims 1 to 4,
The ink jet printer, wherein the liquid suction port communicates with the ink tank, and the liquid ejection port communicates with the ink jet head.

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