JP6277826B2 - Liquid ejection device - Google Patents

Description

  The present invention relates to a liquid ejection apparatus.

  In Patent Document 1, as a liquid ejection device, a liquid ejection head (liquid ejection head) having an ejection port (ejection port) for ejecting ink, a sub tank that stores ink to be supplied to the liquid ejection head, and a sub tank are supplied. An ink jet printer having a main tank for storing ink is disclosed. In this type of ink jet printer, when bubbles enter the liquid ejecting head, there is a problem that ink is not ejected from the ejection port.

  Therefore, in the ink jet printer described in Patent Document 1, the sub tank blocks an ink storage chamber for storing ink, an air chamber formed above the ink storage chamber, and a communication hole between the ink storage chamber and the air chamber. It has a gas permeable membrane, a suction channel connected to the air chamber, and a suction pump that makes the pressure in the air chamber negative through the suction channel. Then, by driving the suction pump to make the pressure in the air chamber negative, the gas flows out from the ink storage chamber to the air chamber, and the gas in the ink storage chamber is removed.

JP 2008-238583 A

  However, in the configuration of the ink jet printer described in Patent Document 1, when all the gas flows out from the ink storage chamber through the suction channel by driving the suction pump, the channel including the suction channel and the air chamber is The flow path is closed at one end by a gas permeable membrane. If the driving of the suction pump is further continued in this state, an excessive pressure is applied to the gas permeable membrane, and the gas permeable membrane may be damaged or peeled off.

  SUMMARY OF THE INVENTION An object of the present invention is to provide a liquid ejection device that prevents an excessive pressure from being applied to a gas permeable membrane.

  In order to solve the above problems, a liquid discharge apparatus according to the present invention includes a liquid discharge head having a discharge port for discharging a liquid, a first liquid tank for storing liquid to be supplied to the liquid discharge head, A second liquid tank for storing liquid to be supplied to the first liquid tank; a communication channel that communicates the first liquid tank with the outside; and the communication channel and the first liquid tank are partitioned. A gas permeable membrane for preventing gas permeation while allowing gas to permeate, a pump provided in the communication channel, for reducing the pressure in the communication channel, and the communication A branch channel that branches from a position where the pump is provided and a position where the gas permeable membrane is disposed in the channel, and communicates with the outside; and the branch channel in the communication channel Branch position and gas permeable membrane An open / close valve provided between the position and the open / close valve, and a control means for controlling the pump and the open / close valve, wherein the control means comprises the communication flow The pump is driven with the on-off valve opened so that the path is opened, and a decompression process for exhausting the gas in the first liquid tank to the outside is performed. The path resistance and the channel resistance of the branch channel are such that the pressure at one end of the communication channel on the first liquid tank side is higher than the pressure on the gas side in the first liquid tank during the decompression process. A negative pressure is set, and the gas in the first liquid tank is set to be exhausted to the outside through the communication channel.

  According to the present invention, the gas in the first liquid tank is exhausted to the outside through the communication channel by the decompression process. Further, even if all the gas in the first liquid tank is exhausted, the communication flow path communicates with the outside through the branch flow path, so that the pressure in the communication flow path does not drop significantly. Thereby, it is possible to prevent an excessive pressure from being applied to the gas permeable membrane.

1 is a schematic side view of an ink jet printer according to a first embodiment. (A) is a top view of the head unit shown in FIG. 1, (b) is a top view of the inkjet head in the head unit shown in (a), (c) is the sectional view on the AA line of (b). It is. It is a schematic sectional drawing of a head unit, a cartridge, and a maintenance unit. It is an electrical block diagram of the inkjet printer shown in FIG. (A) is sectional drawing of the exhaust unit in a head unit, and a maintenance unit, (b) is a fragmentary sectional view of an exhaust unit and a maintenance unit. (A) is a figure which shows the exhaust unit which does not have a branch flow path, (b) is a graph which shows the relationship between the pressure in the exhaust flow path of an exhaust unit, and time. It is an operation | movement flowchart concerning the exhaust_gas | exhaustion purge of an inkjet printer. It is an electrical block diagram of the inkjet printer which concerns on 2nd Embodiment. (A) is an operation | movement flowchart which concerns on the exhaust purge of the inkjet printer which concerns on 2nd Embodiment, (b) is a graph which shows the relationship between the pressure in the exhaust flow path of an exhaust unit, and time. It is a schematic side view of the inkjet printer which concerns on a modification.

(First embodiment)
Hereinafter, the inkjet printer 101 according to the first embodiment will be described with reference to FIGS. In FIG. 3, only the connection mode of the cartridge 5 to one head unit 2 is illustrated.

  As shown in FIG. 1, the ink jet printer 101 has a substantially rectangular parallelepiped casing 101a. A paper discharge unit 15 is provided on the top plate of the housing 101a. In the internal space of the housing 101a, there are an ink discharge mechanism 1, a maintenance unit 9 (see FIG. 3), a transport mechanism 16 for transporting paper P, a paper tray 17 for storing a plurality of paper P in a stacked state, and a cartridge 5. A holder 6 (see FIG. 3) that is detachably mounted, a control device 100 that controls the operation of the entire printer 101, and the like are arranged.

  As shown in FIG. 2A, the ink ejection mechanism 1 includes six head units 2 and a head holding plate 3. The head holding plate 3 is a plate-like body made of a metal material or the like that is parallel to the horizontal plane and is substantially rectangular with the main scanning direction as the longitudinal direction. The lower surface of each head unit 2 is an ejection surface 2a on which a plurality of ejection ports 84 (see FIGS. 2B and 2C) from which ink is ejected are formed. Further, the six head units 2 are attached to the head holding plate 3 so that the ejection surfaces 2a are exposed from the through holes arranged in a staggered manner in the main scanning direction while being separated from each other in the head holding plate 3. . Here, the main scanning direction is a direction parallel to the horizontal plane, which is orthogonal to the conveyance direction (sub-scanning direction) of paper P conveyed by nip rollers 13c and 13d described later.

  Each of the head units 2 has substantially the same configuration, and as shown in FIG. 3, each of the head units 2 is provided on an upper surface of the head 60, an inkjet head 60 (hereinafter, head 60) having a plurality of ejection openings 84, It has a reservoir 70 for temporarily storing ink to be supplied to the head 60 and an exhaust unit 20 for exhausting the gas staying in the reservoir 70. The detailed configuration of the head unit 2 will be described later.

  A cartridge 5 storing ink supplied to each head unit 2 is attached to the holder 6 in a replaceable manner. In addition, a liquid supply pipe 80 connected to the reservoir 70 of each head unit 2 is connected to the holder 6, and the ink stored in the cartridge 5 passes through the liquid supply pipe 80 to each head unit 2. It is supplied to the reservoir 70. The cartridge 5 has an air communication port 7 communicating with the atmosphere. When the cartridge 5 is mounted on the holder 6, the vertical position of the cartridge 5 is below the ejection surface 2 a of the head unit 2. As a result, a water head difference occurs between the ink meniscus formed in the vicinity of the ejection port 84 and the liquid level of the ink in the cartridge 5, and the ink side of the ink meniscus has a negative pressure compared to the atmospheric pressure. As a result, it is possible to prevent ink from being ejected from the ejection port 84 at times other than during image recording. In the present embodiment, the cartridge 5 corresponds to a second liquid tank.

  Here, by setting the vertical position of the cartridge 5 below the ejection surface 2a of the head unit 2, the inside of the reservoir 70 is always placed in a negative pressure environment. As a result, as time passes, external gas passes through the members constituting the reservoir 70 and enters the reservoir 70. In addition, the water stored in the reservoir 70 evaporates with time. When water in the ink evaporates, gas (air) is generated in the reservoir 70 by the evaporated water. Due to such a cause, gas exists in the reservoir 70 over time. When the gas existing in the reservoir 70 flows into the head 60, the flow path in the head 60 is likely to be blocked and the ink ejection characteristics of the head 60 are likely to deteriorate. Need to be removed.

  Therefore, in the present embodiment, the maintenance unit 9 performs an exhaust purge (corresponding to a pressure reduction process) in which the gas existing in the reservoir 70 is exhausted to the outside before flowing into the head 60. In addition to the exhaust purge, the maintenance unit 9 forcibly sucks and discharges ink from the plurality of ejection ports 84 of the head 60, and discharges foreign matter or ink having increased viscosity due to drying from the head 60. , Perform a suction purge. Thus, by performing the exhaust purge and the suction purge by the maintenance unit 9, the ejection function of the head 60 can be maintained and recovered. In the present embodiment, six maintenance units 9 are provided corresponding to each of the six head units 2. The detailed configuration of the maintenance unit 9 will be described later.

  Returning to FIG. 1, the transport mechanism 16 constitutes a transport path of the paper P that passes from the paper tray 17 between the head unit 2 and the platen 19 to the paper discharge unit 15. The transport mechanism 16 includes a pickup roller 12, nip rollers 13a to 13f, and guides 14a to 14e. The pickup roller 12 is driven to rotate by a conveyance motor 130 (see FIG. 4), thereby feeding the sheets P in the sheet tray 17 one by one. The nip rollers 13a to 13f are arranged along the transport path, and apply a transport force to the paper P by being rotationally driven by the transport motor 130 (see FIG. 4). The guides 14a to 14e are respectively disposed between the pickup roller 12 and the nip rollers 13a to 13f in the conveyance path, and the sheet P to which conveyance force is applied by the nip rollers 13a to 13f reaches the next nip rollers 13a to 13f. The paper P is guided. When the paper P transported by the transport mechanism 16 passes between the ejection surface 2a of the head unit 2 and the platen 19, ink is ejected from the ejection ports 84 of the head unit 2, and a desired image is formed on the paper P. It is formed. That is, the printer 101 is of a line type that performs recording with the head unit 2 fixed. The paper P on which the image is formed is further transported by the transport mechanism 16 and discharged to the paper discharge unit 15.

  The control device 100 controls various operations of the printer 101 such as ink ejection from the ejection port 84 of the head unit 2, paper feeding to the head unit 2, and paper ejection printed by the head unit 2. It is something to control. As illustrated in FIG. 4, the control device 100 includes a CPU (Central Processing Unit) 120, a ROM (Read Only Memory) 121, a RAM (Random Access Memory) 122, a control circuit 123, and the like. The ROM 121 stores a control program 121a executed by the CPU 120, various fixed data, and the like. The RAM 122 temporarily stores data (such as image data) necessary for program execution. The control circuit 123 includes various types of printers 101 such as a conveyance motor 130 that drives the pickup roller 12 and the nip rollers 13a to 13f, a head 60 of each head unit 2, a drive motor 47 and a transmission destination switching mechanism 48 described later of the maintenance unit 9. Connected to other devices. In FIG. 4, transmission of control signals from the control device 100 to various devices is illustrated by solid arrows, and for convenience of description, transmission of driving force of the conveyance motor 130 and the driving motor 47 is also illustrated by dotted arrows. ing.

  When the CPU 120 receives a recording command from an external device such as a PC, the CPU 120 controls the head 60 and the transport motor 130 of each head unit 2 according to the control program 121 a stored in the RAM 122 to record an image on the paper P. Perform image recording. In addition, at a predetermined timing such as when the printer 101 is turned on, the CPU 120 controls the drive motor 47 and the transmission destination switching mechanism 48 of the maintenance unit 9 according to the control program 121a stored in the RAM 122, and the above-described exhaust purge. Or perform a vacuum purge. In the present embodiment, the exhaust purge is performed immediately before the suction purge is performed.

  Next, the head 60, the reservoir 70, and the exhaust unit 20 in the head unit 2 will be described in detail with reference to FIGS. 2B, 2C, 3 and 5. FIG. In FIG. 3, the inkjet head 60 is shown as a side view, not a sectional view.

  The reservoir 70 is a member for temporarily storing ink supplied to the ejection port 84 of the head 60. Four ink outflow channels 71a are formed on the lower surface of the reservoir 70, and an inflow port 71b and a communication port 71c are formed on the upper surface. Each of the ink outflow channels 71 a is connected to each of ink supply ports 85 (see FIG. 2B) formed in a later-described channel unit 61 of the head 60. A liquid supply pipe 80 for connecting the head unit 2 and the cartridge 5 is connected to the inflow port 71b. The liquid supply pipe 80 forms an ink flow path from the cartridge 5 to the inflow port 71 b of each head unit 2. When ink is ejected from the ejection port 84 during an image recording operation or the like, the ink stored in the reservoir 70 passes through the ink outflow channel 71a and is supplied from the ink supply port 85 to the channel unit 61. The ink stored in the cartridge 5 passes through the liquid supply pipe 80 and is supplied to the reservoir 70 from the inflow port 71b. In FIG. 3, only one ink outflow channel 71a appears.

  The exhaust unit 20 is made of synthetic resin. As shown in FIG. 5A, the exhaust channel 21, the valve body 22 provided in the exhaust channel 21, and the head unit 2 from the upper surface to the lower surface. And a branched flow path 30 to reach. One end of the exhaust passage 21 is connected to the communication port 71 c of the reservoir 70, and the other end is an exhaust port 23 formed on the lower surface of the head unit 2.

  The valve body 22 includes a valve member 25 and a coil spring 26. The valve member 25 includes a cylindrical valve body 25a that can move in the vertical direction in the exhaust passage 21, and a valve rod 25b that extends downward from the valve body 25a. There is a gap between the wall surface forming the exhaust passage 21 and the outer peripheral surface of the valve body 25a. An annular sealing material 27 is attached to the lower surface of the valve body 25a.

  The upper end of the coil spring 26 is in contact with a spring receiving portion 28 fixedly provided in the exhaust passage 21. The lower end of the coil spring 26 is in contact with the upper surface of the valve body 25a. The coil spring 26 is disposed in a compressed state between the spring receiving portion 28 and the valve body 25a. The valve member 25 is urged downward by the coil spring 26. And the valve body 25a of the valve member 25 contacts the valve seat surface 29 provided in the exhaust flow path 21 via the sealing material 27 as shown in FIG. To do. Further, when the valve rod 25b of the valve member 25 is pushed upward against the urging force of the coil spring 26 by the exhaust member 45 of the maintenance unit 9 described later, the valve body 25a is separated from the valve seat surface 29 and exhausted. The mouth 23 is opened.

  One end of the branch channel 30 is formed on the upper surface of the head unit 2 and communicates with the outside, and the other end is an atmosphere introduction port 32 formed on the lower surface of the head unit 2. Further, the branch channel 30 has a cross-sectional area smaller than the cross-sectional area of the exhaust channel 21, and the channel length is longer than the channel length of the exhaust channel 21 by bending a plurality of times in the vertical direction. As a result, the channel resistance of the branch channel 30 is larger than the channel resistance of the exhaust channel 21.

  As shown in FIG. 5A, the gas permeable membrane 10 is provided at the communication port 71c of the reservoir 70 so as to cover the communication port 71c. That is, the gas permeable membrane 10 is disposed so as to partition the reservoir 70 and the exhaust passage 21. The gas permeable membrane 10 is a membrane for preventing gas permeation while allowing gas permeation. For example, a porous fluororesin membrane is used.

  As shown in FIGS. 2B and 2C, the head 60 is a laminated body including a flow path unit 61 and an actuator unit 64 fixed to the upper surface of the flow path unit 61. On the upper surface of the flow path unit 61, four ink supply ports 85 are formed side by side in the sub-scanning direction. The four ink supply ports 85 are connected to the ink outflow passage 71a of the reservoir 70, and ink is supplied from the inside of the reservoir 70, respectively. The flow path unit 61 includes four manifolds 86 extending in the main scanning direction. The four manifolds 86 are connected to the four ink supply ports 85. Further, a large number of individual ink flow paths are formed in the flow path unit 61 from the outlet of the manifold 86 to the discharge port 84 through the pressure chamber 87. The actuator unit 64 includes a plurality of actuators corresponding to the pressure chambers 87 and has a function of selectively giving ejection energy to the ink in the pressure chambers 87. When a drive signal is supplied from the control device 100 to the actuator, pressure is applied to the ink in the pressure chamber 87 and ink is ejected from the ejection port 84. The lower surface of the flow path unit 61 is a discharge surface 2a, and a large number of discharge ports 84 are arranged.

  Next, the maintenance unit 9 will be described in detail with reference to FIGS. As shown in FIG. 3, the maintenance unit 9 includes a cap unit 35, a cap moving mechanism 38 (see FIG. 4), a maintenance flow path unit 39, a three-way valve 43, a suction pump 44, and an exhaust member 45 (see FIG. 5A). ), An exhaust member moving mechanism 46 (see FIG. 4), a drive motor 47 (see FIG. 4), a transmission destination switching mechanism 48 (see FIG. 4), and the like.

  A drive motor 47 that is a drive source is driven under the control of the control device 100. The transmission destination switching mechanism 48 selectively controls the driving force of the driving motor 47 with respect to any one of the cap moving mechanism 38, the suction pump 44, and the exhaust member moving mechanism 46 under the control of the control device 100. introduce. As the transmission destination switching mechanism 48, for example, a switching gear connected to a drive motor 47, a cap moving mechanism 38, a suction pump 44, and an exhaust member moving mechanism 46 are connected to each other and arranged side by side along a predetermined direction. A mechanism capable of switching the transmission destination of the driving force of the driving motor 47 by moving the switching gear along the predetermined direction and switching the output gear with which the switching gear meshes. Can be adopted. Note that. The transmission destination switching mechanism 48 is not limited to this, and the driving force of the drive motor 47 is selectively applied to any one of the cap moving mechanism 38, the suction pump 44, and the exhaust member moving mechanism 46. Anything can be used.

  The cap unit 35 includes a discharge port cap 36 and an exhaust cap 37 provided on the right side of the discharge port cap 36 in FIG. The cap unit 35 is movable in the main scanning direction and the vertical direction by a cap moving mechanism 38 operated by a drive motor 47. During the image recording operation, the cap unit 35 is disposed at a position on the one side in the main scanning direction from the platen 19 (hereinafter also referred to as a standby position). When the exhaust purge or the suction purge is performed, the cap moving mechanism 38 moves the cap unit 35 in the main scanning direction, the discharge port cap 36 faces the discharge surface 2a of the head 60, and the exhaust cap 37 is the exhaust unit. It is arranged at a facing position facing the lower surface of 20. Thereafter, the cap moving mechanism 38 moves the cap unit 35 upward in the vertical direction so that the discharge port cap 36 is in close contact with the discharge surface 2a of the head 60 and the exhaust cap 37 is in close contact with the lower surface of the exhaust unit 20. (See FIGS. 5A and 5B). In this maintenance position, the plurality of discharge ports 84 are covered with the discharge port cap 36, and the exhaust port 23 of the exhaust flow channel 21 and the air introduction port 32 of the branch flow channel 30 are covered with the exhaust cap 37.

  The maintenance flow path unit 39 includes a suction tube 40 connected to the discharge cap 36, an exhaust tube 41 connected to the exhaust cap 37, and one end connected to each of the suction tube 40 and the exhaust tube 41. And a common tube 42 having the other end connected to the outside. The three-way valve 43 is provided at a connection portion between the common tube 42 and the suction tube 40 and the exhaust tube 41. Under the control of the control device 100, the connection destination of the common tube 42 is the suction tube 40 and the exhaust tube 41. Selectively switch between.

  The suction pump 44 is provided in the common tube 42 and is driven by a drive motor 47. When the suction pump 44 is driven, the pressure in the common tube 42 is reduced so that the gas is transferred from one end of the common tube 42 toward the other end (outside). Specifically, when the suction pump 44 is driven in a state where the cap unit 35 is located at the maintenance position, the inside of the discharge port cap 36 is located when the common tube 42 and the suction tube 40 are connected. It is possible to perform a suction purge in which the pressure is reduced and ink is forcibly sucked and discharged from the plurality of ejection ports 84 of the head 60. On the other hand, when the common tube 42 and the exhaust tube 41 are connected, the inside of the exhaust cap 37 is depressurized.

  The exhaust member 45 is a rod-like member, and penetrates the bottom wall portion of the exhaust cap 37 vertically while maintaining airtightness. When the exhaust cap 37 is in the maintenance position, the exhaust member 45 is positioned directly below the exhaust port 23 of the exhaust passage 21. The exhaust member 45 is moved up and down by an exhaust member moving mechanism 46 driven by a drive motor 47, and is movable between a first position and a second position. In the first position, as shown in FIG. 5B, the distal end portion of the exhaust member moving mechanism 46 is positioned below the upper end of the exhaust cap 37 in the vertical direction. Accordingly, in the first position, the inside of the exhaust cap 37 and the branch passage 30 are communicated with each other, but the communication between the inside of the exhaust cap 37 and the exhaust passage 21 is blocked. When the exhaust member 45 is lifted from the first position by the exhaust member moving mechanism 46 and moved to the second position, as shown in FIG. The valve main body 22 (valve member 25) in the exhaust passage 21 is pushed up, and the exhaust port 23 of the exhaust passage 21 is opened. Therefore, in the second position, the exhaust cap 37 communicates with both the branch channel 30 and the exhaust channel 21.

  Hereinafter, when the cap unit 35 is in the maintenance position (see FIGS. 5A and 5B), a flow path composed of the exhaust flow path 21, the exhaust cap 37, the exhaust tube 41, and the common tube 42 is provided. This is referred to as an exhaust communication channel 50. The exhaust communication channel 50 is connected to the branch channel 30 in the exhaust cap 37. In other words, the branch channel 30 is a channel that branches from the position where the suction pump 44 is provided and the position where the gas permeable membrane 10 is disposed in the exhaust communication channel 50 and communicates with the outside. . In the present embodiment, the valve body 22 in the exhaust unit 20 and the exhaust member moving mechanism 46 in the maintenance unit 9 function as an on-off valve 55 that can open and close the exhaust communication channel 50. The on-off valve 55 (valve body 22) is provided between the branch position of the exhaust communication flow path 50 and the branch flow path 30 (in the exhaust cap 37) and the position where the gas permeable membrane 10 is disposed. Will be. In this embodiment, the on-off valve 55 is closed so that the exhaust communication flow path 50 is closed when the on-off valve 55 is other than the exhaust purge. Accordingly, it is possible to suppress external gas from entering the reservoir 70 via the exhaust communication flow path 50 at a time other than the exhaust purge.

By the way, as described above, when the suction pump 44 is driven in a state where the common tube 42 and the exhaust tube 41 are connected, the inside of the exhaust cap 37 is decompressed. When the on-off valve 55 is open, the inside of the exhaust passage 21 connected to the inside of the exhaust cap 37 is also decompressed. At this time, external gas is taken in from the atmosphere communication port 31 of the branch flow path 30 and is introduced into the exhaust cap 37 from the atmosphere introduction port 32.
Here, when the suction pump 44 is driven, the value of the pressure P1 at one end of the exhaust communication channel 50 (exhaust channel 21) on the reservoir 70 side is the flow of each of the exhaust communication channel 50 and the branch channel 30. Varies with road resistance. For example, the pressure P1 decreases as the channel resistance of the branch channel 30 increases (the negative pressure with respect to atmospheric pressure increases), and the pressure P1 increases as the channel resistance of the branch channel 30 decreases (close to atmospheric pressure). Become).

  In the present embodiment, when the flow resistance of each of the exhaust communication flow path 50 and the branch flow path 30 drives the suction pump 44, the pressure P1 in the exhaust communication flow path 50 becomes the pressure P2 on the gas side in the reservoir 70. The pressure in the reservoir 70 is set to be exhausted to the outside through the exhaust communication channel 50. Therefore, by driving the suction pump 44 with the on-off valve 55 being opened, it is possible to perform an exhaust purge that exhausts the gas in the reservoir 70 to the outside. At this time, the ink stored in the cartridge 5 is supplied to the reservoir 70 through the liquid supply pipe 80 by the volume of the gas exhausted from the reservoir 70 to the outside by the exhaust purge.

  Note that, as described above, the flow path resistance of the branch flow path 30 is larger than the flow path resistance of the exhaust flow path 21, so that the flow path resistance of the branch flow path 30 is the same as the flow path resistance of the exhaust flow path 21. As compared with the case where the suction pump 44 is driven, the pressure P1 of the exhaust passage 21 when the suction pump 44 is driven can be further reduced. As a result, the gas in the reservoir 70 can be efficiently exhausted to the outside. The gas permeable membrane 10 deteriorates with time, and its flow resistance (flow resistance when gas passes through the gas permeable film 10) increases. For example, if ink permeates into the gas permeable membrane 10 by performing an exhaust purge or the like, the flow path resistance increases. Therefore, when the suction pump 44 is driven even when the gas permeable membrane 10 is deteriorated to some extent, the pressure P1 in the exhaust communication channel 50 is reduced to the reservoir resistance of each of the exhaust communication channel 50 and the branch channel 30. It is preferable to set the pressure so that the pressure in the gas side in the gas tank 70 is more negative than the pressure P2 on the gas side, and the gas in the reservoir 70 is exhausted to the outside through the exhaust communication channel 50.

  Further, from the viewpoint of exhausting the gas in the reservoir 70 to the outside and preventing the gas permeable membrane 10 from being applied with excessive pressure, the flow resistance of the branch flow path 30 and the flow resistance of the exhaust flow path 21 are It is desirable that the ratio of the above is in an appropriate range. For example, when the gas permeable membrane 10 has a pressure resistance against ink of 100 kpa and has a property such that gas is sucked at a speed of 0.5 cc / sec when sucked by the suction pump 44 at 10 kpa, the branch flow The ratio of the flow path resistance of the passage 30 and the flow path resistance of the exhaust flow path 21 is preferably in the range of 2: 1 to 10: 1. In this example, if the ratio of the flow path resistance of the branch flow path 30 to the exhaust flow path 21 is less than 2: 1, the difference between the pressure P1 of the exhaust flow path 21 and the pressure P2 in the reservoir 70 during the exhaust purge. And the time for exhausting the gas in the reservoir 70 to the outside becomes longer. On the other hand, when the ratio of the flow path resistance of the branch flow path 30 to the exhaust flow path 21 is larger than 10: 1, the difference between the pressure P1 of the exhaust flow path 21 and the pressure P2 in the reservoir 70 during the exhaust purge is This is because the gas permeable membrane 10 is not damaged in the short term, but is undesirably loaded in the long term.

In the present embodiment, the suction pump 44 is driven for a certain time regardless of the amount of gas staying in the reservoir 70. Specifically, the suction pump 44 is driven for a time required to exhaust the largest amount of gas out of the amount of gas remaining in the reservoir 70 assumed at the start of the exhaust purge.
Here, when the exhaust unit 20 has the branch flow path 30 as in the present embodiment and when the exhaust unit 20 does not have the branch flow path as shown in FIG. A change in the pressure P1 at one end on the reservoir 70 side of the path 50 will be described with reference to FIG. FIG. 6B is a graph showing the relationship between the pressure P1 and the time during the exhaust purge. In addition, the vertical axis | shaft in FIG.6 (b) shows that the pressure P1 is so low that it is an upper side. Further, for convenience of explanation, the pressure P1 when the suction pump 44 is driven in a state where gas stays in the reservoir 70 includes the case where the exhaust unit 20 has the branch flow path 30 and the case where the pressure flow does not have the branch flow path. It shall be unchanged.

  As shown in FIG. 6A, when the exhaust unit 20 does not have a branch flow path, the suction pump 44 is driven with the open / close valve 55 opened, thereby allowing the exhaust unit 20 to pass through the exhaust communication flow path 50. When all the gas in the reservoir 70 is exhausted, the exhaust communication channel 50 becomes a channel whose one end is closed by the gas permeable membrane 10. When the suction pump 44 is further driven in this state, the pressure P1 continues to decrease, and an excessive pressure is applied to the gas permeable membrane 10. As a result, the gas permeable membrane 10 may be damaged or peeled off.

  On the other hand, when the exhaust unit 20 has the branch flow path 30 as in the present embodiment, the suction pump 44 is driven with the on-off valve 55 opened, and the exhaust communication flow path 50 is Even if all the gas in the reservoir 70 is exhausted, the exhaust communication flow path 50 is in communication with the outside via the branch flow path 30, so that the pressure P1 is remarkably high as shown in FIG. It does not decrease and the differential pressure from the pressure in the reservoir 70 does not increase. Therefore, it is possible to prevent an excessive pressure from being applied to the gas permeable membrane 10.

  Next, an example of the exhaust purge executed by the CPU 120 in accordance with the control program 121a stored in the ROM 121 will be described with reference to FIG. In the state at the start of the operation flow of FIG. 7, the cap unit 35 is disposed at the maintenance position.

  First, the CPU 120 executes an exhaust purge start process (decompression start process) in steps S1 to S4 described below as the first process of the exhaust purge. Specifically, the CPU 120 controls the transmission destination switching mechanism 48 to switch the transmission destination of the driving force of the drive motor 47 to the exhaust member moving mechanism 46 (S1). Then, the CPU 120 drives the drive motor 47 to operate the exhaust member moving mechanism 46, thereby moving the exhaust member 45 from the first position to the second position (see FIG. 5A) (S2). Thereby, the on-off valve 55 is opened and the exhaust communication flow path 50 is opened. At this time, since the exhaust communication channel 50 communicates with the branch channel 30, external gas flows into the exhaust communication channel 50 (exhaust channel 21) via the branch channel 30. For this reason, as shown in FIG. 6B, the pressure P <b> 1 rises higher than the pressure P <b> 2 in the reservoir 70, and a small amount of gas in the exhaust passage 21 is moved into the reservoir 70.

  Next, the CPU 120 controls the transmission destination switching mechanism 48 to switch the transmission destination of the driving force of the drive motor 47 to the suction pump 44 (S3). Then, the CPU 120 drives the drive motor 47 to start driving the suction pump 44 (S4). By executing the above process, the exhaust purge start process ends.

  Next, the CPU 120 drives the suction pump 44 for a time required to exhaust the largest amount of gas out of the amount of gas staying in the reservoir 70 assumed at the start of the exhaust purge (S5). ). Thereby, the gas in the reservoir 70 is reliably exhausted to the outside. Thereafter, the CPU 120 executes exhaust purge end processing in steps S6 to S8 described below.

  Specifically, first, the CPU 120 stops driving the suction motor 44 by stopping driving the drive motor 47 (S6). Thereafter, the CPU 120 controls the transmission destination switching mechanism 48 to switch the transmission destination of the driving force of the drive motor 47 to the exhaust member moving mechanism 46 (S7). Then, the CPU 120 drives the drive motor 47 to operate the exhaust member moving mechanism 46, thereby moving the exhaust member 45 from the second position to the first position (see FIG. 5B) (S8). As a result, the on-off valve 55 is closed and the exhaust communication flow path 50 is closed. By executing the above processing, the exhaust purge end processing is completed. In the exhaust purge end process of the present embodiment, the driving of the suction pump 44 is stopped and then the on-off valve 55 is closed. Therefore, the driving of the suction pump 44 is stopped and then the on-off valve 55 is closed. In the meantime, external gas flows into the exhaust communication flow path 50 (exhaust flow path 21) via the branch flow path 30, and the pressure P1 in the exhaust flow path 21 increases. Therefore, since the pressure applied to the gas permeable membrane 10 after exhaust purging can be made smaller than the pressure applied when the suction pump 44 is driven, the gas permeable membrane 10 is prevented from being damaged or peeled off. Can do.

  Further, when the pressure P1 in the exhaust flow path 21 increases, the gas in the exhaust flow path 21 may be transferred into the reservoir 70, but the transfer amount blocks the flow path in the head 60. There is no particular problem as long as there is no fear. In addition, when the gas permeable membrane 10 is in contact with the ink, the ink penetrates into the gas permeable membrane 10 with the passage of time, so that solid components in the ink (such as high-boiling powders. For example, pigments contained in the ink) (Applicable)) stays in the gas permeable membrane 10 and clogs the gas flow path in the gas permeable membrane 10, so that the gas permeation in the state in contact with the ink is larger than in the state in contact with the ink. Deterioration of performance advances. Therefore, in the exhaust purge end process, the gas permeation performance of the gas permeable membrane 10 is deteriorated by transferring the gas in the exhaust passage 21 into the reservoir 70 and retaining a small amount of gas in the reservoir 70. The effect which suppresses doing can also be acquired. The example of the exhaust purge has been described above.

  As described above, according to the present embodiment, the gas in the reservoir 70 can be exhausted to the outside through the exhaust communication channel 50 by the exhaust purge. Even if all the gas in the reservoir 70 is exhausted, the pressure P1 of the exhaust communication flow path 50 does not significantly decrease because the exhaust communication flow path 50 communicates with the outside through the branch flow path 30. . Thereby, it is possible to prevent an excessive pressure from being applied to the gas permeable membrane 10.

  Further, according to the present embodiment, the open / close valve 55 is closed so that the exhaust communication flow path 50 (exhaust flow path 21) is closed at times other than the exhaust purge. Accordingly, it is possible to prevent the gas from flowing into the reservoir 70 from the outside via the exhaust communication channel 50 at a time other than the exhaust purge. Further, since the suction pump 44 and the on-off valve 55 (exhaust member moving mechanism 46) are driven by the same drive motor 47, the printer 101 can be reduced in size compared to the case where the drive motor is provided individually. .

  Further, since the flow path resistance of the branch flow path 30 is larger than the flow path resistance of the exhaust flow path 21, the flow path resistance of the branch flow path 30 is the same as or equal to the flow path resistance of the exhaust flow path 21. The pressure P1 of the exhaust passage 21 at the time of exhaust purging can be further reduced as compared with the case where it is smaller than that. As a result, the gas in the reservoir 70 can be efficiently exhausted to the outside.

(Second Embodiment)
Next, a second embodiment will be described with reference to FIGS. The second embodiment is different from the first embodiment in that the cap moving mechanism 38, the suction pump 44, and the exhaust member moving mechanism 46 are driven by a common drive motor 47 in the first embodiment. In the second embodiment, as shown in FIG. 8, the transmission destination switching mechanism 48 is not provided, and individual drive motors 151 to 153 are provided for the cap moving mechanism 38, the suction pump 44, and the exhaust member moving mechanism 46, respectively. This is the point. Further, the exhaust purge start process and the exhaust purge end process included in the exhaust purge are different from those in the first embodiment. Below, the same code | symbol is attached | subjected about the location same as 1st Embodiment mentioned above, and the description is abbreviate | omitted suitably.

  An example of the exhaust purge executed by the CPU 120 according to the control program 121a stored in the ROM 121 according to the present embodiment will be described with reference to FIG. In addition, in the state at the time of the start of the operation | movement flow of Fig.9 (a), the cap unit 35 is arrange | positioned in the maintenance position.

  First, the CPU 120 executes an exhaust purge start process of steps A1 and A2 described below as the first process of the exhaust purge. Specifically, the CPU 120 drives the drive motor 151 to start driving the suction pump 44 (A1). Thereafter, the CPU 120 drives the drive motor 152 to operate the exhaust member moving mechanism 46, thereby moving the exhaust member 45 from the first position to the second position (see FIG. 5A) (A2). Thereby, the on-off valve 55 is opened and the exhaust communication flow path 50 is opened. As described above, in the exhaust purge start processing according to the present embodiment, the suction pump 44 is driven when the exhaust communication channel 50 is opened, so that external gas is exhausted through the branch channel 30. Inflow into the flow path 21 can be suppressed. Therefore, as shown in FIG. 9B, during the exhaust purge start process, the pressure P1 of the exhaust passage 21 is kept constant without increasing.

  Next, the CPU 120 drives the suction pump 44 for a time required to exhaust the largest amount of gas out of the amount of gas staying in the reservoir 70 assumed at the start of the exhaust purge (A3). ). Thereby, the gas in the reservoir 70 is reliably exhausted to the outside. Since the pressure P1 of the exhaust passage 21 is kept constant during the exhaust purge start process as described above, the pressure P1 is increased during the exhaust purge start process as in the first embodiment. In comparison, since the pressure P1 in the exhaust passage 21 can be made faster than the pressure P2 in the reservoir 70, the time for driving the suction pump 44 (exhaust purge processing time) can be shortened.

  Thereafter, the CPU 120 executes exhaust purge end processing in steps A4 and A5 described below. Specifically, first, the CPU 120 drives the drive motor 152 and operates the exhaust member moving mechanism 46 to move the exhaust member 45 from the second position to the first position (see FIG. 5B). (A4). As a result, the on-off valve 55 is closed and the exhaust communication flow path 50 is closed. And CPU120 stops the drive of the suction pump 44 by stopping the drive of the drive motor 151 (A5). As described above, in the exhaust purge end process according to the present embodiment, when the drive of the suction pump 44 is stopped, since the exhaust communication flow path 50 is closed, external gas passes through the branch flow path 30. Thus, it is possible to suppress the flow into the exhaust passage 21. The example of the exhaust purge has been described above.

  As described above, also in the present embodiment, the gas in the reservoir 70 can be exhausted to the outside through the exhaust communication channel 50 by the exhaust purge. Even if all the gas in the reservoir 70 is exhausted, the pressure P1 of the exhaust communication flow path 50 does not significantly decrease because the exhaust communication flow path 50 communicates with the outside through the branch flow path 30. . Thereby, it is possible to prevent an excessive pressure from being applied to the gas permeable membrane 10.

  Further, in this embodiment, since the exhaust communication flow path 50 is opened after the suction pump 44 is started to be driven, it is possible to suppress external gas from flowing into the exhaust flow path 21 through the branch flow path 30. Can do. As a result, the exhaust purge processing time can be shortened. In addition, in the exhaust purge termination process, when the drive of the suction pump 44 is stopped, the exhaust communication channel 50 is closed, so that external gas flows into the exhaust channel 21 via the branch channel 30. Can be suppressed. As a result, by performing the exhaust purge, all the gas staying in the reservoir 70 can be reliably exhausted to the outside.

  The preferred embodiment of the present invention has been described above. However, the present invention is not limited to the above-described embodiment, and various design changes can be made as long as they are described in the claims. Is. Hereinafter, a modification will be described with reference to FIG. In FIG. 10, for convenience of explanation, the head units 202 adjacent in the main scanning direction are illustrated apart from each other in the main scanning direction.

  In the above embodiment, each head unit 2 includes a part of the exhaust communication passage 50 (exhaust passage 21) and a part of the on-off valve 55 (valve body 22). Then, each head unit 202 does not include a part of the exhaust communication passage and a part of the on-off valve. The gas permeable membrane 10 is not provided in the communication port 71 c of the reservoir 70, but is provided as a partition wall that extends horizontally in the internal space of the reservoir 70. By this gas permeable membrane 10, the internal space of the reservoir 70 is partitioned into an upper gas chamber 70a and a lower ink chamber 70b. The inflow port 71b is formed in the ink chamber 70b, and the ink stored in the cartridge 5 is supplied from the inflow port 71b to the ink chamber 70b via the liquid supply pipe 80. In this modification, the ink chamber 70b corresponds to the first liquid tank.

  In the above-described embodiment, six maintenance units 9 are provided corresponding to each of the six head units 202. However, in this modification, a common maintenance unit 209 is provided for the six head units 202. Yes. As shown in FIG. 10, the maintenance unit 209 includes a suction purge unit 220 for performing a suction purge and an exhaust purge unit 250 for performing an exhaust purge.

  The suction purge unit 220 includes six discharge port caps 236 for each of the six head units 202, a suction tube 237 that communicates each of the six discharge port caps 236 with the outside, and a pump 238 provided in the suction tube 237. Yes. The pump 238 is driven in a state where the discharge port cap 236 is disposed at the maintenance position by a cap moving mechanism (not shown), so that suction purge can be performed.

  The exhaust purge unit 250 includes an exhaust tube 251, a branch tube 252, an on-off valve 253, and a pump 254. The exhaust tube 251 is a flow path member that communicates the gas chamber 70 a in the reservoir 70 with the outside, and includes six individual tubes 255 and a common tube 256. The common tube 256 is a flow path member common to the six individual tubes 255, and one end thereof is connected to the outside. Each of the six individual tubes 255 has one end connected to the communication port 71 c of the reservoir 70 in the corresponding head unit 202. In this modification, the six individual tubes 255 are branched from one individual tube 255 connecting the common port 256 and the communication port 71c of the reservoir 70 of the head unit 202 at the left end in FIG. Each of the five head units 202 includes five individual tubes 255 that reach the communication ports 71 c of the reservoirs 70. For this reason, in this modification, the channel resistances of the channels from the communication ports 71c of the reservoirs 70 of the six head units 202 to the outside are different from each other. The six individual tubes 255 are individually branched from the common tube 256 so that the flow resistances of the flow paths extending from the communication ports 71c of the reservoirs 70 of the six head units 202 to the outside are the same. The head unit 202 may be configured to reach the communication port 71 c of the reservoir 70 of each head unit 202.

  The pump 254 is provided in the common tube 256, and under the control of the control device 100, the gas is transferred from the communication port 71 c of the reservoir 70 of each of the six head units 202 toward the outside. The pressure of is reduced.

  The branch tube 252 is a flow path member that branches from between the connection location of the individual tube 255 and the position where the pump 254 is provided in the common tube 256 to the outside. The cross-sectional area of the branch tube 252 is smaller than the cross-sectional area of the common tube 256 and the cross-sectional area of the individual tube 255. In addition, the flow path length of the branch tube 252 is made longer than the flow path length from the branch position of the exhaust tube 251 (common tube 256) to the branch tube 252 to the communication port 71c of the reservoir 70 in each head unit 202. ing. Therefore, the flow resistance of the branch tube is made larger than the flow resistance from the branch position of the exhaust tube 251 with the branch tube 252 to the communication port 71 c of the reservoir 70 in each head unit 202. In addition, also in the head unit 202 at the left end in FIG. 10 in which the flow path resistance from the communication port 71c to the common tube 256 is the largest, when the pump 254 is driven, the ink chamber 70b in the reservoir 70 of the head unit 202 is provided. The flow path resistance of the branch tube 252 is set so that the pressure in the gas chamber 70a becomes negative than the pressure on the gas side. Thereby, when the pump 254 is driven, the gas in the ink chamber 70 b of the reservoir 70 in all the head units 202 can be exhausted to the outside through the exhaust tube 251.

  The on-off valve 253 is provided between the connection location of the individual tube 255 and the branch position of the branch tube 252 in the common tube 256, and opens and closes the flow path of the common tube 256 under the control of the control device 100. In this modification, the flow path including the gas chamber 70a of the reservoir 70, the individual tube 255, and the common tube 256 constitutes an exhaust communication flow path 260 that communicates the ink chamber 70b (first liquid tank) with the outside.

  In the above configuration, by driving the pump 254 with the on-off valve 253 opened, the gas in the ink chamber 70b of the reservoir 70 in all the head units 202 is exhausted to the outside through the exhaust communication channel 260. Can be made. Even if all the gas in the ink chamber 70b is exhausted, the exhaust communication flow path 260 communicates with the outside through the branch tube 252, so that the pressure in the exhaust communication flow path 260 does not significantly decrease. . Thereby, it is possible to prevent an excessive pressure from being applied to the gas permeable membrane 10. In the above, this modification was demonstrated.

  As another modified example, in the second embodiment described above, the exhaust purge start process is such that after the suction pump 44 is driven, the on-off valve 55 is opened so that the exhaust communication flow path 50 is opened. Similarly to the first embodiment, the suction pump 44 may be driven after the on-off valve 55 is opened so that the exhaust communication flow path 50 is opened. In addition, in the second embodiment described above, in the exhaust purge end process, the driving of the suction pump 44 is stopped after the open / close valve 55 is closed so that the exhaust communication flow path 50 is closed. Similarly to the embodiment, after the driving of the suction pump 44 is stopped, the on-off valve 55 may be closed so that the exhaust communication flow path 50 is closed.

In the above-described embodiment, the on-off valve 55 that opens and closes the exhaust communication channel 50 is closed during a period other than the exhaust purge, but is configured to open during a predetermined period other than the exhaust purge. It may be.
In the above embodiment, the flow path resistance of the branch flow path 30 is larger than the flow path resistance of the exhaust flow path 21, but the gas in the reservoir 70 corresponding to the driving force of the suction pump 44 is exhausted to the outside. If it does not concern about improving the exhaust efficiency at the time of making it, it will not be restricted to this structure.

  The present invention can be applied to both a line type and a serial type, and is not limited to a printer, and can also be applied to a facsimile, a copier, and the like. The present invention can also be applied to a liquid ejecting apparatus that ejects liquid other than ink.

5 Cartridge (second liquid tank)
10 Gas permeable membrane 30 Branch flow path 44 Suction pump (pump)
50 Exhaust communication channel (communication channel)
55 On-off valve 60 Inkjet head (liquid discharge head)
70 Reservoir (first liquid tank)
84 Ejection port 100 Control device 101 Inkjet printer (liquid ejection device)

Claims (8)

A liquid discharge head having a discharge port for discharging liquid;
A first liquid tank for storing liquid to be supplied to the liquid discharge head;
A second liquid tank for storing liquid to be supplied to the first liquid tank;
A communication channel that communicates the first liquid tank with the outside;
A gas permeable membrane disposed so as to partition the communication channel and the first liquid tank to prevent the permeation of liquid while allowing the permeation of gas;
A pump provided in the communication channel, for reducing the pressure in the communication channel;
A branch channel that branches from between the position where the pump is provided and the position where the gas permeable membrane is disposed in the communication channel, and communicates with the outside;
An on-off valve provided between the branch position of the communication channel and the branch channel and the position where the gas permeable membrane is disposed, and capable of opening and closing the communication channel;
Control means for controlling the pump and the on-off valve;
The control means includes
The pump is driven in a state where the on-off valve is opened so that the communication channel is opened, and a decompression process for exhausting the gas in the first liquid tank to the outside is performed.
The channel resistance of the communication channel and the channel resistance of the branch channel are:
During the decompression process, the pressure at one end of the communication channel on the first liquid tank side is more negative than the pressure on the gas side in the first liquid tank, and the gas in the first liquid tank is A liquid ejecting apparatus, wherein the liquid ejecting apparatus is set to be exhausted to the outside through a communication flow path. The control means includes
2. The liquid ejection device according to claim 1, wherein the on-off valve is closed so that the communication flow path is closed at a time other than the decompression process. The control means includes
As the process included in the decompression process, after the drive of the pump is stopped, a decompression end process for closing the open / close valve so as to close the communication channel is performed at the end of the decompression process. The liquid ejection device according to claim 1 or 2. The control means includes
As the process included in the decompression process, after the on-off valve is closed so that the communication flow path is closed, a decompression end process for stopping driving of the pump is performed at the end of the decompression process. The liquid ejection device according to claim 1 or 2. The pump and the on-off valve are driven by the same drive source, and the drive source can selectively transmit the driving force to either the pump or the on-off valve.
The control means includes
The pump and the on-off valve are controlled via the drive source,
The depressurization start process for driving the pump is performed at the beginning of the depressurization process after the open / close valve is opened so that the communication flow path is opened as a process included in the depressurization process. Item 4. The liquid ejection device according to Item 3. The control means includes
The decompression start process for opening the on-off valve to open the communication flow path after the pump is driven as the process included in the decompression process is performed at the beginning of the decompression process. Item 5. The liquid ejection device according to any one of Items 1 to 4.   The flow path resistance of the branch flow path is larger than the flow path resistance between the position where the gas permeable membrane is disposed and the branch position in the communication flow path. The liquid ejection device according to any one of the above. The first liquid tank is disposed vertically above the second liquid tank,
The liquid discharge apparatus according to claim 1, further comprising a liquid supply pipe for connecting the first liquid tank and the second liquid tank.