JP2011161716A - Liquid ejecting apparatus, and cleaning method in liquid ejecting apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a liquid ejecting apparatus which can perform cleaning by suppressing the consumption of liquid after the end of the cleaning, and to provide a cleaning method in a liquid ejecting apparatus. <P>SOLUTION: The liquid ejecting apparatus includes nozzles 30 which eject inks, an ink flow passage 32 which supplies the ink from an upstream side toward a downstream side, a maintenance pump 61 which can suck and discharge the ink from the ink flow passage 32, a one-way valve 51 which opens in accordance with decompression at the downstream side thereby allowing the passage of the ink from the upstream side to the downstream side, and a control unit 72 which performs cleaning processing by controlling the drive of the maintenance pump 61. The control unit 72 makes the maintenance pump 61 discharge the ink from a pressure changing position PH in the ink flow passage 32 into the ink flow passage 32 by driving the maintenance pump 61 to perform a discharging operation, and then makes the maintenance pump 61 suck the ink from the pressure changing position PH in the ink flow passage 32 by driving the maintenance pump 61 to perform a sucking operation. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a liquid ejecting apparatus such as an ink jet printer, and a cleaning method in the liquid ejecting apparatus.

  Conventionally, ink jet printers are widely known as liquid ejecting apparatuses that eject liquid onto a target. This printer performs printing (image formation) on a target by ejecting ink (liquid) supplied to a recording head (liquid ejecting head) from a nozzle formed on the recording head.

  In such a printer, if air bubbles are mixed in, the meniscus is increased, or the ink is thickened, the ink cannot be ejected satisfactorily and the print quality is deteriorated. Therefore, in such a printer, as described in Patent Document 1, for example, the ink is pressurized and supplied from the upstream side, which is the ink cartridge side that contains ink, to the downstream side, which is the recording head side, and the ink is discharged from the nozzles. Therefore, cleaning (pressure cleaning) is performed.

  In such a printer, back pressure is applied to the ink so that the ink meniscus is positioned near the nozzle opening. As a configuration for applying a back pressure to ink, generally, a one-way valve that allows passage of ink from the upstream side to the downstream side when the downstream side is depressurized is used. In other words, the one-way valve has a pressure chamber whose volume changes in response to a change in pressure on the downstream side, and when the pressure on the downstream side is reduced, the pressure chamber contracts and opens, whereas ink is applied from the upstream side. Even if pressure is supplied, the valve closed state is maintained.

  Therefore, in the case where the ink is pressurized and supplied from the cartridge side to the nozzle side as in the printer of Patent Document 1, the ink is pressurized on the downstream side of the one-way valve.

JP 2007-152725 A

  By the way, when the ink is pressurized downstream of the one-way valve, the pressure is transmitted to the one-way valve, so that the pressure chamber expands and accumulates the pressure. For this reason, when performing cleaning by pressurizing the ink downstream of the one-way valve as in the printer of Patent Document 1, the back pressure of the ink cannot be adjusted by the one-way valve. The applied pressure accumulated in the chamber is transmitted to the nozzle side. In other words, even after the cleaning is completed, the ink overflows from the nozzles, and a lot of ink may be wasted due to the cleaning.

  The present invention has been made in view of the above problems, and an object thereof is to provide a liquid ejecting apparatus capable of performing cleaning while suppressing consumption of liquid after completion of cleaning, and a cleaning method in the liquid ejecting apparatus. There is to do.

  In order to achieve the above object, a liquid ejecting apparatus of the present invention includes a nozzle that ejects liquid, and a liquid supply flow that supplies the liquid from an upstream side that is a liquid supply source side to a downstream side that is the nozzle side. A pump capable of sucking the liquid in the liquid supply flow channel from a first position in the liquid supply flow channel and discharging the liquid from the first position into the liquid supply flow channel The pressure chamber that is provided at the second position upstream of the first position in the liquid supply flow path and whose volume changes according to the pressure change at the downstream side contracts according to the pressure reduction at the downstream side. A one-way valve that allows the liquid to pass from the upstream side to the downstream side, and a control unit that controls the driving of the pump to perform a cleaning process, and the control unit includes the pump The pump is driven by discharging After the liquid is discharged from the first position in the liquid supply channel into the liquid supply channel, the pump is sucked to drive the pump from the first position in the liquid supply channel. The liquid is aspirated.

  According to this configuration, it is possible to perform a cleaning process in which the liquid is supplied to the nozzle side via the liquid supply channel and the liquid is discharged from the nozzle by driving the pump to discharge. At this time, since the pump discharges the liquid into the liquid flow path at the first position, the discharge pressure also acts on the pressure chamber of the one-way valve provided at the second position. The one-way valve then accumulates the applied pressure by expanding the pressure chamber while maintaining the closed state. However, since the pump is driven to perform suction after being driven to discharge, it is possible to suppress the transmission of the applied pressure to the nozzle side by sucking the liquid in the liquid supply channel and contracting the pressure chamber. Therefore, the cleaning can be performed while suppressing the consumption of the liquid after the cleaning is completed.

  In the liquid ejecting apparatus according to the aspect of the invention, the pump may change the volume of the variable volume liquid chamber that communicates with the inside of the liquid supply flow path, the volume variable gas chamber that stores gas, and the volume of the liquid chamber and the gas chamber. A volume changing unit that controls the volume changing unit to reduce the volume of the gas chamber to reduce the compressed pressure of the gas with respect to the liquid in the liquid chamber. By operating, the pump is driven to discharge.

  When the viscosity of the liquid is increased or when bubbles are mixed in the liquid, the fluidity of the liquid is lowered. In that respect, according to this configuration, by compressing the gas in the gas chamber and applying the pressure of the compressed gas to the liquid in the liquid chamber, the liquid can be ejected vigorously into the liquid supply channel. it can. That is, since it is not necessary to provide a configuration for accumulating the pressure of a pump such as a valve in the liquid supply flow path, an increase in the number of parts can be suppressed and the liquid flow rate can be increased.

In the liquid ejecting apparatus according to the aspect of the invention, the amount of the liquid that can be sucked by the pump with suction driving is larger than the change amount of the volume of the pressure chamber.
According to this configuration, the pressure chamber that has expanded along with the pump discharge drive can be contracted to the minimum volume by the pump suction drive, so that the transmission of the applied pressure to the nozzle side can be suppressed. it can. Further, when the pump sucks liquid that exceeds the amount of change in the pressure chamber, the pressure chamber is depressurized, so that the one-way valve is opened and the liquid is supplied from the upstream side into the pressure chamber. Therefore, consumption of the liquid after cleaning can be suppressed and the pressure on the downstream side of the one-way valve in the liquid supply channel can be adjusted.

  The cleaning method in the liquid ejecting apparatus of the present invention includes a nozzle that ejects liquid, a liquid supply channel that supplies the liquid from an upstream side that is the liquid supply source side to a downstream side that is the nozzle side, and the liquid supply flow A pump capable of sucking the liquid in the liquid supply channel from a first position in the channel and capable of discharging the liquid from the first position into the liquid supply channel; and in the liquid supply channel Provided at a second position upstream of the first position, and opens when the pressure chamber whose volume changes in response to downstream pressure changes contracts in accordance with downstream pressure reduction. In a cleaning method in a liquid ejecting apparatus including a one-way valve that allows passage of the liquid from the side to the downstream side, the liquid supply flow from the first position in the liquid supply flow path by sucking and driving the pump A first suction stage that sucks the liquid in the first suction stage, and the pump is driven to discharge from the first position in the liquid supply flow path into the liquid supply flow path in the first suction stage. A discharge step of discharging the liquid; and a second suction step of sucking the liquid in the liquid supply channel by sucking the pump after discharging the liquid in the discharge step.

According to this configuration, the same function and effect as the invention relating to the liquid ejecting apparatus can be achieved.
In the cleaning method in the liquid ejecting apparatus according to the aspect of the invention, the discharging step discharges the liquid sucked in the first suction step and the second suction step.

  According to this configuration, the liquid sucked in the second suction stage at the previous cleaning can be used for cleaning. In other words, when cleaning is performed, it is not necessary to suck all of the ink necessary for cleaning in the first suction step, so that cleaning can be performed quickly.

1 is a schematic diagram of a printer according to an embodiment. FIG. 2 is a schematic diagram of an ink supply system. FIG. 3 is a schematic cross-sectional view taken along arrow 3-3 in FIG. 2. The schematic diagram of the maintenance pump of a standby state. The schematic diagram of the maintenance pump at the time of completion | finish of suction drive. The schematic diagram of the maintenance pump at the time of a suction drive start. The schematic diagram of the nozzle at the time of the suction drive of a maintenance pump. The schematic diagram of the nozzle at the time of the discharge drive of a maintenance pump. The schematic diagram of the nozzle after completion | finish of cleaning.

  Hereinafter, an embodiment in which a fluid ejecting apparatus of the invention is embodied in an ink jet printer will be described with reference to the drawings. In the following description, “left-right direction” and “up-down direction” refer to the left-right direction and the up-down direction indicated by arrows in FIG. 1, respectively. Further, when referring to the “front-rear direction”, the direction orthogonal to the paper surface of FIG.

  As shown in FIG. 1, an ink jet printer (hereinafter, also referred to as “printer”) 11 as a liquid ejecting apparatus prints the paper 12 and a transport unit 13 for transporting the paper 12 as a target. Recording head unit 15.

  The transport unit 13 includes a rectangular plate-shaped platen 17 that is long in the left-right direction. A drive roller 18 extending in the front-rear direction is disposed on the right side of the platen 17 so as to be rotationally driven by a drive motor 19, while a driven roller 20 extending in the front-rear direction is disposed on the left side of the platen 17 so as to be rotatable. Further, a tension roller 21 extending in the front-rear direction is rotatably disposed below the platen 17.

  An endless transport belt 22 having a large number of through holes is wound around the drive roller 18, the driven roller 20, and the tension roller 21 so as to surround the platen 17. In this case, the tension roller 21 is urged downward by a spring member (not shown), and by applying tension to the conveyor belt 22, looseness of the conveyor belt 22 is suppressed.

  Then, when the driving roller 18 is rotationally driven in the clockwise direction when viewed from the front side, the conveying belt 22 is rotated in the clockwise direction when the outer side of the driving roller 18, the tension roller 21, and the driven roller 20 is viewed from the front side. It has become. Further, when the sheet 12 is at a position facing the upper surface of the platen 17, the sheet 12 is sucked to the platen 17 side through the conveying belt 22 by a suction unit (not shown), and is conveyed from the upstream left side to the downstream right side. It has come to be.

  A pair of upper and lower paper feed rollers 23 for feeding a plurality of unprinted paper sheets 12 one by one onto the transport belt 22 one by one is provided on the upper left side of the driven roller 20. On the other hand, on the diagonally upper right side of the driving roller 18, a pair of upper and lower paper discharge rollers 24 for discharging the printed paper 12 one by one from the transport belt 22 are provided.

  As shown in FIGS. 1 and 2, the recording head unit 15 includes a plurality of (four in the present embodiment) recording heads 26 to 29 extending in the front-rear direction and spaced in the left-right direction. Is provided. In addition, on the nozzle formation surfaces 26a to 29a that are the lower surfaces of the recording heads 26 to 29, a large number of nozzles 30 are regularly formed at predetermined intervals in the front-rear direction so as to form nozzle rows along the front-rear direction. It is open. The nozzles 30 thus configured are supplied with the same type of ink (liquid) for each of the recording heads 26 to 29 and ejected from the nozzles 30.

  That is, as shown in FIG. 2, the first recording head 26 receives black ink from an ink cartridge 31 serving as a liquid supply source containing black ink via an ink flow path 32 serving as a liquid supply flow path. Is connected to the ink supply device 33. Similarly, the second to fourth recording heads 27 to 29 are connected to an ink supply device 33 that supplies ink from ink cartridges 31 containing inks of cyan, magenta, and yellow, respectively.

  However, since the configuration of the ink supply device 33 that supplies ink from each ink cartridge 31 to each recording head 26 to 29 is the same, FIG. 2 shows one ink supply device that supplies ink to the first recording head 26. Only 33 is shown together with the first recording head 26 and the ink cartridge 31. In the following description, the first recording head 26 and the ink supply device 33 that supplies ink to the first recording head 26 shown in FIG. 2 will be described as an example.

  As shown in FIGS. 2 and 3, a reservoir 36 communicating with the downstream side of the ink flow path 32 is formed in the first recording head 26 so as to extend in the front-rear direction along the nozzle row. A plurality of branch flow paths 35 individually corresponding to the nozzles 30 are branched from a plurality of positions in the extending direction of the reservoir 36. In addition, the downstream end position in the reservoir 36 that is a branch point of the branch flow path 35 is a branch position PB.

  The branch channel 35 includes a cavity 37 that communicates with the nozzle 30, and a communication channel 38 that communicates the cavity 37 and the reservoir 36. Note that the cross-sectional area of the communication flow path 38 is smaller than the cross-sectional area of the cavity 37 in the direction orthogonal to the direction in which the ink flows (direction orthogonal to the paper surface in FIG. 3).

  Further, as shown in FIG. 3, a piezoelectric element 40 is disposed at a position adjacent to the cavity 37 via a diaphragm 39 that forms one wall surface of the cavity 37. That is, the piezoelectric element 40 contracts and expands to vibrate the diaphragm 39, thereby changing the volume of the cavity 37 and ejecting ink from the nozzle 30. When the ink in the cavity 37 decreases with ejection, the ink is supplied from the ink cartridge 31 side via the communication channel 38, the reservoir 36, and the ink channel 32. Accordingly, the branch flow path 35, the reservoir 36, and the ink flow path 32 function as a liquid supply flow path that can supply ink from the upstream side that is the ink cartridge 31 side to the downstream side that is the nozzle 30 side.

  The nozzle 30 has a tapered portion 42 that gradually decreases in cross-sectional area from the upstream side to the downstream side that is connected to the cavity 37, and an opening 43 that communicates with the tapered portion 42 and opens to the nozzle forming surface 26a. It consists of and. When the nozzle 30 is filled with ink from the upstream side, a meniscus M is formed in the nozzle 30 and in the vicinity of the nozzle opening 44 opened in the nozzle forming surface 26a. The meniscus M is a curved surface that is formed by a capillary phenomenon so that the central portion of the ink rises so as to form a concave shape when viewed from the nozzle opening 44.

  In addition, as shown in FIG. 2, the ink cartridge 31 has a case 47 in which an ink pack 46 that contains ink and has flexibility. A pressure pump 49 is connected to the case 47 via an air flow path 48, and an upstream end of the ink flow path 32 is connected to the ink pack 46. Therefore, when the pressure pump 49 supplies air into the case 47 through the air flow path 48, the ink pack 46 is crushed and the ink in the ink pack 46 is supplied to the ink flow path 32. Yes.

  Then, in the ink flow path 32, the pressure adjustment position PT as the second position allows the ink to pass from the upstream side to the downstream side as the downstream pressure is reduced, and the pressure in the ink flow path 32 is increased. A one-way valve 51 for adjustment is provided. In other words, the one-way valve 51 includes a storage chamber 52 that primarily stores ink pressurized and supplied from the ink cartridge 31, and a pressure chamber 53 that is positioned downstream of the storage chamber 52. The storage chamber 52 and the pressure chamber 53 are separated from each other by a partition wall portion 54, and communicated by a valve body 56 that is urged by a spring 55 in the valve closing direction and abuts against the partition wall portion 54 in the valve opening direction. It is supposed to be.

  Therefore, when ink is ejected from the nozzle 30 and consumed, the pressure chamber 53 is depressurized, and the film 57 is bent and deformed toward the pressure chamber 53 based on the pressure difference between the pressure chamber 53 and the atmosphere. When this bending force becomes larger than the urging force of the spring 55, the valve body 56 moves to the valve opening position away from the partition wall 54, and the pressurized ink in the storage chamber 52 flows into the pressure chamber 53 side. When ink flows into the pressure chamber 53 and the chamber pressure increases, the urging force of the spring 55 overcomes and the valve body 56 moves to the valve closing position where it abuts against the partition wall 54 again.

  As described above, the one-way valve 51 is opened by the pressure reduction on the downstream side of the valve body 56, whereas when the upstream side is pressurized, the valve body 56 receives a force in the closing direction, so that the valve is opened. Keep valve closed without valve. Similarly, when the downstream side is pressurized, the film 57 bends and deforms in the direction of increasing the volume of the pressure chamber 53, so that the valve body 56 closes without receiving a force in the valve opening direction from the film 57. Maintain valve status. Furthermore, since the upstream ink is pressurized by the pressurizing pump 49, the upstream side of the valve body 56 is not depressurized. That is, the one-way valve 51 is a valve that opens only when the downstream side is depressurized.

  A part of the pressure chamber 53 is constituted by a film 57 made of a flexible material (for example, synthetic resin or rubber). For example, a cantilever metal piece (for example, comb teeth) that can be displaced together with the film 57 is used. A piece of metal piece) is arranged at the contact point of the valve body 56.

  Also, a maintenance pump 61 as a pump capable of changing the pressure in the ink flow path 32 and sucking and discharging ink is connected to the transformation position PH as the first position downstream of the pressure adjustment position PT. Has been.

  The maintenance pump 61 is a pump that can pressurize the ink in the recording head 26. That is, although the pressurizing pump 49 is provided separately from the maintenance pump 61, pressurization by the pressurizing pump 49 is blocked by the one-way valve 51, and the pressurizing force cannot be transmitted to the recording head 26. Therefore, in order to perform maintenance of the recording head 26, a maintenance pump 61 capable of pressurizing the ink in the recording head 26 is required in addition to the pressurizing pump 49.

  As shown in FIG. 4, the maintenance pump 61 includes a flexible tube 62, a frame body 63 that supports the tube 62, and a pressing mechanism 64 that can press the tube 62. The base end portion 62a of the tube 62 is connected to the ink flow path 32, whereas the tip end portion 62b of the tube 62 is closed.

  The frame 63 has a base end support portion 63a, a tip end support portion 63b, and an intermediate support portion 63c that support the base end portion 62a, the tip end portion 62b, and the intermediate portion 62c of the tube 62, respectively. The proximal end support portion 63a and the distal end support portion 63b in the frame 63 are formed in a cylindrical shape so as to support the proximal end portion 62a and the distal end portion 62b of the tube 62 in an inserted state. The intermediate support portion 63c in the frame 63 is a plate-like body that connects the base end support portion 63a and the distal end support portion 63b, and is supported from the outer peripheral side in a state where the intermediate portion 62c of the tube 62 is curved in an arc shape. As shown, the cross section is bent in an arc shape.

  A pressing mechanism 64 is disposed at an inner (inner peripheral side) position of the intermediate portion 62c of the tube 62 that is supported in an arcuate shape by the intermediate support portion 63c of the frame 63. The pressing mechanism 64 includes a rotating plate 66 that can rotate around a drive shaft 65, and a pressing roller 67 that is rotatably provided at the tip of a tongue piece 66a that protrudes radially outward of the rotating plate 66. ing. The pressing roller 67 presses the intermediate portion 62c of the tube 62 from the inner peripheral side toward the intermediate support portion 63c side of the frame 63 so as to crush the tube 62 in cooperation with the intermediate support portion 63c. It is arranged so that it can be pinched.

  Therefore, the inside of the tube 62 (specifically, the intermediate part 62c) is a liquid chamber on the base end part 62a side, with the pressing point 62d being crushed by the pressing roller 67 and the intermediate support part 63c of the frame 63 as a boundary. Are divided into an ink chamber 69 and a gas chamber 70 on the front end 62b side. That is, the ink chamber 69 communicates with the ink flow path 32 and is filled with ink. On the other hand, gas (for example, air) is accommodated in the gas chamber 70.

  When the drive shaft 65 rotates with the driving of the pressing motor 68 (see FIG. 2), the pressing roller 67 rotates with the rotating plate 66 in the direction indicated by the white arrow in FIG. It has become. That is, when the pressing roller 67 rotates and moves while the tube 62 is crushed, the volume of the ink chamber 69 increases and the pressing point 62d moves in the direction in which the volume of the gas chamber 70 decreases. Therefore, the pressing roller 67 functions as a volume changing unit that changes the volumes of the ink chamber 69 and the gas chamber 70.

  Specifically, as shown in FIG. 4, when the pressing roller 67 located at the standby position P1 rotates and moves to the suction end position P2 shown in FIG. Ink is sucked from the path 32. On the other hand, the volume of the gas chamber 70 decreases, and the stored gas is compressed.

  Therefore, when the pressing roller 67 is further rotated from the suction end position P2 and is positioned in the non-nipping region A, the nipping state of the tube 62 is released, and the pressure of the compressed gas stored in the gas chamber 70 is changed to the ink chamber. Acts on the ink in 69. Therefore, the ink moves to the base end portion 62 a side so as to be pushed by the gas and is discharged into the ink flow path 32. That is, the non-clamping region A is a position where the pressing roller 67 is not opposed to the intermediate support part 63 c via the tube 62.

  When the pressing roller 67 further rotates and moves to the clamping region B where the tube 62 can be clamped together with the intermediate support portion 63c, the pressing roller 67 presses the tube 62 against the intermediate support portion 63c as shown in FIG. Hold it. That is, the clamping region B is a position where the pressing roller 67 is opposed to the intermediate support portion 63c via the tube 62, and is a position where the tube 62 can be pressed and pressed against the intermediate support portion 63c side. Then, the pressure roller 67 further rotates from the suction start position P3 shown in FIG. 6 to suck the ink in the ink flow path 32 into the ink chamber 69.

  Accordingly, the maintenance pump 61 is driven to discharge and suck by the pressing motor 68 rotating the drive shaft 65. In the present embodiment, the thickness and length of the tube 62 are such that the volume of the tube 62 between the suction start position P3 and the standby position P1 is equal to or greater than the volume change amount of the pressure chamber 53 due to the displacement of the film 57. Is set.

  Further, as shown in FIG. 2, the printer 11 is provided with a control unit 72 as a control unit that performs overall control of the operating state of the printer 11. The control unit 72 drives and controls the piezoelectric elements 40, the pressure pumps 49, and the pressing motors 68 provided in the recording heads 26 to 29 to perform printing and cleaning processes.

Next, the operation of the printer 11 configured as described above will be described below.
When printing is started in the printer 11, the control unit 72 creates ink ejection timing for each nozzle 30 based on the print data, and drives the piezoelectric element 40 based on the ejection timing. Then, the vibration plate 39 is displaced in the direction of decreasing the volume of the cavity 37 and ejects ink from the nozzle 30. In other words, the ink ejected from each nozzle 30 adheres to the paper 12 supported by the transport belt 22 and transported, whereby the paper 12 is printed.

  When ink is ejected from the nozzle 30 and consumed, the reduced pressure accompanying the decrease in ink is transmitted to the one-way valve 51 via the reservoir 36 and the ink flow path 32. Then, the valve body 56 moves to the valve opening position against the urging force of the spring 55, and the ink in the storage chamber 52 flows into the pressure chamber 53 side. When ink flows into the pressure chamber 53 and the chamber pressure increases, the urging force of the spring 55 overcomes and the valve body 56 moves to the valve closing position again.

  Accordingly, the one-way valve 51 allows the ink to pass from the upstream side to the downstream side in accordance with the pressure reduction on the downstream side, so that the consumed ink is supplied from the ink cartridge side. Therefore, even when ink is ejected from the nozzles during printing, the position of the meniscus M is located in the vicinity of the nozzle opening 44 as shown in FIG.

  By the way, if the period during which printing is not executed and ink is not ejected from the nozzles becomes long, the ink may evaporate from the nozzle openings 44 to increase the viscosity of the ink or the position of the meniscus M may increase. The rise in the position of the meniscus M may occur not only in ink evaporation but also in other scenes such as when the printer 11 receives an impact or when the end of the paper 12 contacts the nozzle opening 44.

  Therefore, the control unit 72 executes the cleaning process when, for example, a cleaning process execution command is received from a user (not shown) from the user or when it is determined that a predetermined time has passed since the previous cleaning process. It is assumed that the pressing roller 67 of the maintenance pump 61 is positioned at the standby position P1 in the clamping region B during printing or standby during non-cleaning processing.

  Now, the controller 72 drives the pressing motor 68 to rotate the pressing roller 67 about the drive shaft 65 once. That is, the pressing roller 67 located at the standby position P1 moves to the suction end position P2 side, and passes through the non-nipping area A and the suction start position P3 to return to the standby position P1.

  Specifically, since the volume of the ink chamber 69 increases while moving from the standby position P1 to the suction end position P2, the maintenance pump 61 is driven to suck and suck ink from the ink flow path 32 (first). Suction phase).

  When the maintenance pump 61 is driven to suck, ink is sucked from the nozzle 30 side downstream of the transformation position PH in the ink flow path 32. Therefore, the position of the meniscus M located in the vicinity of the nozzle opening 44 rises as shown in FIG. 7, and the position of the meniscus M that has been raised originally increases further. Further, the negative pressure accompanying the suction drive of the maintenance pump 61 also acts on the upstream side of the transformation position PH. Therefore, the film 57 is displaced in the direction in which the volume of the pressure chamber 53 decreases, and the one-way valve 51 is opened, so that ink is also supplied from the ink cartridge 31 side.

  When the pressing roller 67 further rotates from the suction end position P2 and moves to the non-clamping area A, the maintenance pump 61 is driven to discharge. That is, the pressure of the gas in the gas chamber 70 acts on the ink in the ink chamber 69, and the ink in the ink chamber 69 is discharged into the ink flow path 32 (discharge stage).

  Meanwhile, the one-way valve 51 provided on the upstream side of the transformation position PH in the ink flow path 32 opens when the pressure is reduced from the downstream side, but closes when pressurized from the downstream side. Maintain valve status. For this reason, when ink is discharged from the maintenance pump 61, the one-way valve 51 is closed, so that it is supplied to the nozzle 30 side downstream of the pressure adjustment position PT. The ink discharged by the maintenance pump 61 along with the discharge drive includes the ink filled in the ink chamber 69 when the pressing roller 67 is located at the standby position P1, and the ink sucked in the first suction drive stage. Is the sum of Furthermore, since ink is also sucked from the ink cartridge 31 side during suction driving, the amount of ink supplied to the nozzle 30 side during ejection driving is larger than the amount of ink sucked from the nozzle 30 side in the first suction stage.

  Therefore, when the maintenance pump 61 is driven to discharge, ink thickened near the nozzle opening 44 or ink mixed with bubbles is discharged together with the ink supplied from the maintenance pump 61 side, and the recording head 26 is cleaned. By the way, when ink is discharged from the nozzle 30 during cleaning, the ink may adhere to the nozzle forming surface 26a near the nozzle opening 44 (see FIG. 8).

  Further, when the maintenance pump 61 is driven to discharge, the discharge pressure of the maintenance pump 61 acts on the pressure chamber 53, and the film 57 is bent and deformed to the atmospheric pressure side to increase the volume of the pressure chamber 53. Therefore, in the pressure chamber 53 in which the volume is increased and the applied pressure is accumulated, a negative pressure cannot be applied to the ink. Further, the accumulated applied pressure is transmitted to the nozzle 30 side and the ink is discharged from the nozzle 30. May continue.

  However, the pressing roller 67 passes through the non-clamping region A and rotates and moves to the suction start position P3 that is closer to the base end portion 62a than the suction end position P2 to crush the tube 62. Furthermore, the control unit 72 stops the driving of the pressing motor 68 at the timing when the pressing roller 67 is positioned at the standby position P1. That is, since the volume of the ink chamber 69 increases while the pressing roller 67 moves from the suction start position P3 to the standby position P1, the maintenance pump 61 is driven to suck and suck ink from the ink flow path 32 (second). Suction phase).

  Then, since the ink is sucked from the nozzle 30 side on the downstream side of the transformation position PH, the ink attached near the nozzle opening 44 is sucked into the nozzle 30. Further, since the ink in the pressure chamber 53 is sucked upstream from the transformation position PH, the film 57 is bent and deformed to the storage chamber 52 side, and the pressurized state is eliminated. By the way, in this embodiment, the volume of the tube 62 between the suction start position P3 and the standby position P1 is set to be equal to or larger than the volume change amount of the pressure chamber 53 accompanying the displacement of the film 57. Therefore, when ink larger than the volume change amount of the pressure chamber 53 is sucked by the suction driving of the maintenance pump 61, the one-way valve 51 is opened and ink is supplied from the ink cartridge 31 side. Therefore, as shown in FIG. 9, the meniscus M is located in the vicinity of the nozzle opening 44.

According to the above embodiment, the following effects can be obtained.
(1) By performing a discharge drive of the maintenance pump 61, it is possible to perform a cleaning process of supplying ink to the nozzle 30 side via the ink flow path 32 and discharging the ink from the nozzle 30. At this time, since the maintenance pump 61 discharges ink into the ink flow path 32 at the transformation position PH, the discharge pressure also acts on the pressure chamber 53 of the one-way valve 51 provided at the pressure adjustment position PT. Then, the one-way valve 51 accumulates the applied pressure by expanding the pressure chamber 53 while maintaining the closed state. However, since the maintenance pump 61 is driven to suck after being driven to discharge, the pressure chamber 53 is contracted by sucking the ink in the ink flow path 32, thereby suppressing the transmission of the applied pressure to the nozzle 30 side. it can. Therefore, it is possible to perform cleaning while suppressing ink consumption after completion of cleaning.

  (2) When the viscosity of the ink is increased or when bubbles are mixed in the ink, the fluidity of the ink is lowered. In that respect, by compressing the gas in the gas chamber 70 and applying the compressed gas pressure to the ink in the ink chamber 69, the ink can be ejected vigorously into the ink flow path 32. That is, since it is not necessary to provide the ink flow path 32 with a configuration for accumulating the pressure of the maintenance pump 61 such as a valve, an increase in the number of components can be suppressed and the ink flow rate can be increased.

  (3) Since the pressure chamber 53 expanded with the discharge driving of the maintenance pump 61 can be contracted to the minimum volume by the suction driving of the maintenance pump 61, the transmission of the applied pressure to the nozzle 30 side is suppressed. can do. Further, when the maintenance pump 61 sucks ink exceeding the change amount of the pressure chamber 53, the pressure chamber 53 is depressurized, so that the one-way valve 51 is opened and the ink enters the pressure chamber 53 from the upstream side. Is supplied. Therefore, consumption of ink after cleaning can be suppressed, and the pressure on the downstream side of the one-way valve 51 in the ink flow path 32 can be adjusted.

  (4) At the time of the previous cleaning, the ink sucked by the pressing roller 67 moving from the suction start position P3 to the standby position P1 can be used for cleaning. In other words, when cleaning is performed, it is not necessary to suck all the amount of ink necessary for cleaning, so that cleaning can be performed promptly.

In addition, you may change the said embodiment as follows.
In the above embodiment, the pressing roller 67 may be positioned at the suction end position P2 during non-cleaning, and the pressing roller 67 may be rotated once around the drive shaft 65 from the suction end position P2 during cleaning. That is, the maintenance pump 61 may be in a state where the volume of the ink chamber 69 is increased and the volume of the gas chamber 70 is reduced and the gas is compressed. In this case, when the control unit 72 drives the pressing motor 68, the pressing roller 67 moves to the non-nipping region A and the maintenance pump 61 is driven to discharge. Subsequently, since the pressing roller 67 moves while the tube 62 is crushed in the clamping region B, the volume of the ink chamber 69 gradually increases and ink is sucked from the ink flow path 32. That is, the pressurizing force remaining in the ink flow path 32 can be recovered by driving the maintenance pump 61 to perform suction after discharging.

  In the above embodiment, in the maintenance pump 61, the volume of the tube 62 between the suction start position P3 and the suction end position P2 is set to be equal to or greater than the volume change amount accompanying the displacement of the film 57 in the pressure chamber 53. May be. Further, at the time of ejection driving at a stage before the maintenance pump 61 is stopped, it is preferable to suck the ink to such an extent that the applied pressure accumulated in the pressure chamber 53 can be recovered.

  In the above embodiment, the maintenance pump 61 may be a piston pump or a diaphragm pump that changes the volume of the ink chamber by displacing the diaphragm. Then, the volume of the ink chamber and the gas chamber may be changed with the movement of the piston or the diaphragm. The maintenance pump 61 is a gear pump or a vane pump having an ink storage chamber. When the suction pump is driven, the ink is moved from the ink flow path 32 to the ink storage chamber. The ink may be moved to 32.

  In the above embodiment, the maintenance pump 61 performs the suction drive and the discharge drive by reciprocating the pressure roller 67 while the tube 62 is held between the pressure roller 67 and the intermediate support portion 63c. Also good. That is, the control unit 72 controls the pressing motor 68 so as to reciprocate the pressing roller 67 in the clamping region B. Then, when the pressure roller 67 moves in the clockwise direction in FIG. 4 from the suction start position P3 to the suction end position P2, the maintenance pump 61 is driven to suck, whereas the maintenance pump 61 starts from the suction end position P2 to the suction start position P3. In the case of moving in the counterclockwise direction, the ejection drive is performed. In the case where the pressing roller 67 is reciprocated in the clamping region B, the distal end portion 62b of the tube 62 may be opened and the gas chamber 70 may not be provided.

  -In above-mentioned embodiment, the frame 63 may support the tube 62 linearly, and if the pressing point 62d can be changed in the state which crushed the tube 62, a clamping means can be changed arbitrarily. . That is, for example, the tube 62 may be clamped by a pair of pressing rollers.

  In the above embodiment, the cleaning process may be performed by rotating the pressing roller 67 a plurality of times around the drive shaft 65. That is, for example, when the degree of viscosity increase of the ink and the degree of increase in the position of the meniscus M are high, there is a possibility that the maintenance pump 61 may not recover by one ejection drive. In that respect, the state of the nozzle 30 can be recovered by executing the ejection driving a plurality of times. Even when the maintenance pump 61 is driven a plurality of times, the ink can be prevented from overflowing from the nozzles 30 during the suction drive by performing the suction drive between the ejection drives. Further, by stopping the pressing roller 67 at the standby position P1, the maintenance pump 61 can be stopped after being driven by suction, so that the overflow of ink from the nozzles 30 can be suppressed even after the cleaning is completed. .

  In the above embodiment, the maintenance pump 61 may be connected to the reservoir 36 so that ink in the reservoir 36 is sucked and discharged. That is, the transformation position PH to which the maintenance pump 61 is connected can be arbitrarily set between the pressure regulation position PT and the branch position PB.

  In the above embodiment, the liquid ejecting apparatus is embodied in the ink jet printer 11, but a liquid ejecting apparatus that ejects or discharges liquid other than ink may be employed. The present invention can be used for various liquid ejecting apparatuses including a liquid ejecting head that ejects a minute amount of liquid droplets. In addition, a droplet means the state of the liquid discharged from the said liquid ejecting apparatus, and shall also include what pulls a tail in granular shape, tear shape, and thread shape. The liquid here may be any material that can be ejected by the liquid ejecting apparatus. For example, it may be in a state in which the substance is in a liquid phase, such as a liquid with high or low viscosity, sol, gel water, other inorganic solvents, organic solvents, solutions, liquid resins, liquid metals (metal melts ) And a liquid as one state of a substance, as well as a material in which particles of a functional material made of a solid such as a pigment or metal particles are dissolved, dispersed or mixed in a solvent. Further, representative examples of the liquid include ink and liquid crystal as described in the above embodiment. Here, the ink includes general water-based inks and oil-based inks, and various liquid compositions such as gel inks and hot melt inks. As a specific example of the liquid ejecting apparatus, for example, a liquid containing a material such as an electrode material or a color material used for manufacturing a liquid crystal display, an EL (electroluminescence) display, a surface emitting display, a color filter, or the like in a dispersed or dissolved state. It may be a liquid ejecting apparatus for ejecting, a liquid ejecting apparatus for ejecting a bio-organic material used for biochip manufacturing, a liquid ejecting apparatus for ejecting a liquid as a sample used as a precision pipette, a textile printing apparatus, a microdispenser, or the like. In addition, transparent resin liquids such as UV curable resin to form liquid injection devices that pinpoint lubricant oil onto precision machines such as watches and cameras, and micro hemispherical lenses (optical lenses) used in optical communication elements. A liquid ejecting apparatus that ejects a liquid onto the substrate or a liquid ejecting apparatus that ejects an etching solution such as an acid or an alkali to etch the substrate may be employed. The present invention can be applied to any one of these liquid ejecting apparatuses.

  DESCRIPTION OF SYMBOLS 11 ... Printer (liquid ejecting apparatus), 12 ... Paper (target), 30 ... Nozzle, 31 ... Ink cartridge (liquid supply source), 32 ... Ink channel (liquid supply channel), 35 ... Branch channel (liquid supply) Flow path), 36 ... reservoir (liquid supply flow path) 51 ... one-way valve, 53 ... pressure chamber, 61 ... maintenance pump (pump), 67 ... pressure roller (volume changing means), 69 ... ink chamber (liquid chamber) , 70 ... gas chamber, 72 ... control part (control means), PH ... transformation position (first position), PT ... pressure regulation position (second position).

Claims (5)

A nozzle for ejecting liquid;
A liquid supply flow path for supplying the liquid from an upstream side which is a liquid supply source side toward a downstream side which is the nozzle side;
A pump capable of sucking the liquid in the liquid supply channel from a first position in the liquid supply channel and capable of discharging the liquid from the first position into the liquid supply channel;
When a pressure chamber provided at a second position upstream of the first position in the liquid supply channel and whose volume changes in response to a pressure change on the downstream side contracts in response to a pressure reduction on the downstream side. A one-way valve that opens to allow the liquid to pass from the upstream side to the downstream side;
Control means for controlling the driving of the pump to perform a cleaning process,
The control means causes the pump to discharge-drive the pump after discharging the liquid from the first position in the liquid supply channel into the liquid supply channel by driving the pump to discharge. The liquid ejecting apparatus according to claim 1, wherein the liquid is sucked from the first position in the liquid supply flow path by the pump. The pump has a variable volume liquid chamber communicating with the liquid supply flow path,
A variable volume gas chamber for containing gas;
A volume changing means for changing the volume of the liquid chamber and the gas chamber;
The control means controls the volume changing means to drive the discharge of the pump by causing the pressure of the gas compressed by reducing the volume of the gas chamber to act on the liquid in the liquid chamber. The liquid ejecting apparatus according to claim 1, wherein: 3. The liquid ejecting apparatus according to claim 1, wherein an amount of liquid that can be sucked by the pump when the pump is driven is larger than a change amount of a volume of the pressure chamber. A nozzle for ejecting liquid;
A liquid supply channel for supplying the liquid from an upstream side which is a liquid supply source side to a downstream side which is the nozzle side;
A pump capable of sucking the liquid in the liquid supply channel from a first position in the liquid supply channel and capable of discharging the liquid from the first position into the liquid supply channel;
When a pressure chamber provided at a second position upstream of the first position in the liquid supply channel and whose volume changes in response to a pressure change on the downstream side contracts in response to a pressure reduction on the downstream side. And a one-way valve that allows the liquid to pass from the upstream side to the downstream side in a cleaning method in a liquid ejecting apparatus,
A first suction stage for sucking the liquid in the liquid supply channel from the first position in the liquid supply channel by suction driving the pump;
A discharge stage that discharges the liquid sucked in the first suction stage from the first position in the liquid supply flow path into the liquid supply flow path by discharging the pump;
A cleaning method for a liquid ejecting apparatus, comprising: a second suction stage for sucking the liquid in the liquid supply channel by sucking and driving the pump after discharging the liquid in the discharge stage. 5. The cleaning method for a liquid ejecting apparatus according to claim 4, wherein the discharging stage discharges the liquid sucked in the first suction stage and the second suction stage. 6.

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