JP5045311B2 - Droplet ejector - Google Patents

Description

  The present invention relates to a droplet ejecting apparatus that ejects droplets.

  Conventionally, as a liquid droplet ejecting apparatus that ejects liquid droplets, an ink jet recording apparatus that records characters and images on printing paper by ejecting ink droplets from nozzles onto a recording medium such as printing paper is known. It has been. A general inkjet recording apparatus includes an inkjet head (droplet ejection head) having a plurality of nozzles, and an ink cartridge that stores ink and is connected to the inkjet head. When ink is consumed by ejecting ink droplets from a plurality of nozzles of the inkjet head, the ink is supplied from the ink cartridge to the inkjet head.

  By the way, in the flow path (liquid supply flow path) connecting the ink jet head and the ink cartridge, bubbles may be mixed from the outside due to factors such as replacement of the ink cartridge. When such air bubbles mixed in the liquid supply flow path flow to the ink jet head together with the ink, there is a possibility of causing an ink ejection failure at the nozzle. Therefore, conventionally, the ink is sucked from the nozzle of the ink jet head by a suction pump or the like, so that bubbles existing in the liquid supply channel on the upstream side of the ink jet head are discharged together with the ink from the nozzle. Has been proposed.

  For example, in the ink jet recording apparatus of Patent Document 1, a damper chamber for absorbing ink pressure fluctuation is provided in the middle of a liquid supply flow path connecting an ink jet head and an ink cartridge. When a certain amount of bubbles accumulates in the damper chamber, ink is sucked from the nozzles by a suction pump, and the bubbles in the damper chamber located upstream of the inkjet head are discharged from the nozzles. Yes.

JP 2005-199600 A

  However, in the above-described ink jet recording apparatus of Patent Document 1, in order to discharge the bubbles in the damper chamber located further upstream than the ink jet head from the nozzles of the ink jet head, the air is not sucked with a considerably strong suction force. There is a problem that the amount of ink discharged from the nozzle together with the bubbles is considerably increased.

  The object of the present invention is to quickly discharge a bubble from the nozzle of the droplet ejecting head when discharging the bubble present in the liquid supply channel for supplying the liquid to the droplet ejecting head, and to discharge the bubble. Accordingly, a liquid droplet ejecting apparatus capable of reducing the amount of liquid discharged from the nozzle is provided.

  The droplet ejecting apparatus of the present invention includes a droplet ejecting head having a nozzle for ejecting droplets, a liquid supply channel for supplying a liquid to the droplet ejecting head, and a liquid in the liquid supply channel. A suction means for sucking from the nozzle of the droplet discharge head, and a gas transfer for capturing the gas in the liquid supply channel and moving the captured gas toward the nozzle on the downstream side during the suction operation of the suction means Means.

  According to the liquid droplet ejecting apparatus of the present invention, when the liquid in the liquid supply channel is sucked from the nozzle by the suction unit, the gas transfer unit moves to the nozzle side in a state of capturing the bubbles in the liquid supply channel. is doing. As a result, the bubbles can be moved to the nozzle side, so that the bubbles can be quickly discharged from the nozzle as compared with the case where the bubbles are discharged only by suction by the suction means. The amount of liquid discharged can be reduced.

Further, in the present invention, the gas transfer means are movably disposed in the flow path extending direction of the liquid supply passage smell Teso gas trapping member for trapping gas in the liquid supply passage And a driving means for moving the gas trapping member in the flow path extending direction, and the gas trapping member itself or between the gas trapping member and the inner wall surface of the liquid supply channel. A liquid passage is formed through which the liquid can pass beyond the gas capturing member when the capturing member moves in the flow path extending direction. According to this configuration, by moving the gas trapping member in a state where the bubbles are trapped in the flow path extending direction by the driving means, only the bubbles are trapped in the gas trapping member while the liquid escapes upstream from the liquid passage. As it is, it can be transferred downstream.

  Furthermore, it is preferable that the downstream surface of the gas capturing member is inclined toward the downstream side with respect to a plane orthogonal to the flow path extending direction from the center toward the outer periphery. According to this configuration, the downstream surface of the gas trapping member is inclined toward the downstream side with respect to the plane perpendicular to the flow path extending direction from the center toward the outer periphery, such as a hemispherical shape or a mortar shape. Therefore, the bubbles are easily guided and gathered by the buoyancy in the center of the gas trapping member, and the trapping of the bubbles by the gas trapping member is ensured. That is, even if the posture of the gas trapping member is slightly deviated, the trapped bubbles are difficult to escape.

  Further, the projected area of the gas capturing member in the flow path extending direction is smaller than a cross-sectional area in a plane orthogonal to the flow path extending direction of the liquid supply flow path, and the outer peripheral surface of the gas capturing member and the The liquid passage is preferably formed between the inner wall surface of the liquid supply flow path. According to this configuration, a liquid passage can be easily formed between the gas capturing member and the liquid supply flow path only by making the outer shape of the gas capture member slightly smaller than the cross section (inner peripheral surface) of the liquid supply flow path. can do.

  Furthermore, a brush-like gas blocking member that allows passage of liquid in the liquid passage and can block passage of gas is provided in a portion of the gas capturing member facing the liquid passage. Is preferred. According to this configuration, when the gas capturing member moves downstream, the liquid escapes to the upstream side from a small gap of the brush-like gas blocking member. On the other hand, when there is a bubble that is not trapped by the gas trapping member and tries to move upstream from the liquid passage, the bubble is caught without being able to pass through the gap of the brush-like gas blocking member, so it escapes to the upstream side. Can be prevented.

  In addition, it is preferable to include a spring member that urges the gas trapping member in the flow path extending direction to stabilize the posture of the gas trapping member. According to this configuration, since the gas trapping member is biased in the flow path extending direction, the posture of the gas trapping member is stabilized, and the bubbles trapped by the gas trapping member are difficult to escape.

  The liquid supply channel extends in the vertical direction with a liquid storage chamber for storing a liquid, and is connected to a liquid outlet of the liquid storage chamber at an upper end portion of the liquid supply flow path. A vertical flow path connected to a droplet ejection head, and the gas capturing member is arranged so as to be movable in the vertical direction in the vertical flow path, and is not sucked by the suction means, When the gas capturing member stands by at the upper end in the vertical flow path, the position of the gas capturing member is preferably higher than the liquid outlet of the liquid storage chamber. According to this configuration, when the gas trapping member is waiting at the upper end of the vertical flow path, the gas trapping member is located at a position higher than the liquid outlet of the liquid reservoir, and thus flows from the liquid reservoir. Air bubbles tend to collect on the lower side of the gas capturing member. Therefore, by moving the gas capturing member to the downstream side during suction by the suction means, a large amount of bubbles can be transferred to the downstream side at a time, and the bubbles can be efficiently discharged.

  Further, the droplet ejecting head is mounted on a carriage that can reciprocate along one direction, and is configured to eject droplets from the nozzle when in a predetermined droplet ejecting region, The suction means has a cap that is disposed in the suction area outside the one direction with respect to the droplet ejecting area and can cover the nozzle of the droplet ejecting head, and the driving means is the suction means When the carriage moves to the suction area where the cap is disposed in order to perform the suction operation, the gas trapping member is moved along the flow path extending direction in conjunction with the movement of the carriage. It is preferably configured to move. According to this configuration, when the carriage is moved to the suction region where the cap is disposed, the driving unit moves the gas capturing member to the downstream side in conjunction with the movement of the carriage. Therefore, it is not necessary to provide a special drive means for moving the gas trapping member, and the cost increase can be suppressed.

  In addition, when the liquid droplet ejecting head moves out of the liquid droplet ejecting area together with the carriage, power is transmitted from the carriage to the driving means for the first time, and the gas trapping member driven by the driving means is It is preferable to start moving to the downstream side. According to this configuration, since the gas capturing member starts to move to the downstream side by the driving unit after the droplet ejecting head has moved out of the droplet ejecting region, the gas is moved during the carriage movement accompanying the normal droplet ejecting operation. It is possible to prevent the capture member from moving in the flow path extending direction and the liquid flow in the liquid supply flow path from becoming unstable.

When the liquid in the liquid supply channel is sucked from the nozzle by the suction unit, the gas transfer unit moves to the nozzle side in a state where air bubbles in the liquid supply channel are captured. As a result, the bubbles can be moved to the nozzle side, so that the bubbles can be quickly discharged from the nozzle as compared with the case where the bubbles are discharged only by suction by the suction means. The amount of liquid discharged can be reduced. Further, by moving the gas trapping member in a state in which the bubbles are trapped in the flow path extending direction by the driving means, the liquid escapes from the liquid passage to the upstream side, while only the bubbles are trapped in the gas trapping member, and the downstream side Can be transferred to.

  Next, a preferred embodiment of the present invention will be described. In the present embodiment, the present invention is applied to a printer that records (prints) desired characters or images on a recording sheet by ejecting ink droplets onto the recording sheet from an inkjet head.

  FIG. 1 is a plan view illustrating a schematic configuration of a printer according to the present embodiment. As shown in FIG. 1, a printer 1 (droplet ejecting apparatus) includes a carriage 2 configured to reciprocate along one direction, an ink jet head 3 (droplet ejecting head) mounted on the carriage 2, Also, the sub tanks 4a to 4d, the ink cartridges 6a to 6d for storing ink, the suction cap 13 attached to the droplet ejection surface of the inkjet head 3, and the suction pump 14 (suction means) connected to the suction cap 13 ) Etc.

  The carriage 2 is configured to be able to reciprocate along two guide shafts 17 extending in parallel in the left-right direction (scanning direction) in FIG. Further, an endless belt 18 is connected to the carriage 2, and when the endless belt 18 is driven to travel by the carriage drive motor 19, the carriage 2 moves in the left-right direction as the endless belt 18 travels. It has become.

  An ink jet head 3 and four sub tanks 4 are mounted on the carriage 2. The inkjet head 3 reciprocates in the scanning direction together with the carriage 2 and from a nozzle 40 (see FIG. 2) provided on the lower surface (the surface on the opposite side of the paper surface of FIG. 1) by a paper transport mechanism (not shown). Ink droplets are ejected onto the recording paper P transported downward (paper feeding direction). As a result, desired characters, images, and the like are recorded on the recording paper P.

  The four sub tanks 4 are arranged side by side along the scanning direction. These four sub tanks 4 are integrally provided with a tube joint 20. The four sub tanks 4a to 4d and the four ink cartridges 6a to 6d are connected to each other through flexible tubes 5a to 5d connected to the tube joint 20.

  The four ink cartridges 6a to 6d store four colors of ink of black, yellow, cyan, and magenta, respectively, and these ink cartridges 6a to 6d are detachably mounted on the holder 7. Although not shown in FIG. 1, the holder 7 is provided with a cartridge detection sensor 85 (see FIG. 8) for detecting whether or not the four ink cartridges 6a to 6d are mounted. The cartridge detection sensor 85 is, for example, an optical sensor having a light emitting element and a light receiving element. Light from the light emitting element is blocked by the ink cartridges 6a to 6d mounted on the holder 7, and received by the light receiving element. By not doing so, it is possible to adopt one that detects the mounting state. Alternatively, when the ink cartridges 6a to 6d are mounted on the holder 7, the contact provided on the holder 7 side and the contact provided on the ink cartridge 6a to 6d side come into contact with each other, and both the contacts are conducted. It may be of a contact type that detects the ink cartridges 6a to 6d.

  The four color inks stored in the four ink cartridges 6a to 6d are temporarily stored in the sub tanks 4a to 4d, and then supplied to the inkjet head 3. That is, the four sub tanks 4a to 4d and the tubes 5a to 5d connecting the four sub tanks 4a to 4d and the four ink cartridges 6a to 6d constitute a liquid supply flow path for supplying ink to the inkjet head 3. ing.

  The suction cap 13 is a region outside the printing region (droplet ejection region) facing the recording paper P (right side in FIG. 1) (hereinafter also referred to as a suction region) within the moving range of the carriage 2 in the scanning direction. Is arranged. The suction cap 13 faces the lower surface of the inkjet head 3 (the liquid droplet ejection surface on which the plurality of nozzles 40 are arranged) when the carriage 2 moves to the suction area. Furthermore, the suction cap 13 is configured to be able to cover the plurality of nozzles 40 of the inkjet head 3 by being driven upward (front side in FIG. 1) by a cap drive motor 84 (see FIG. 8). Yes.

  The suction cap 13 is connected to the suction pump 14 via the switching unit 15. The ink is sucked and discharged from the nozzle 40 by operating the suction pump 14 in a state where the suction cap 13 covers the droplet ejection port of the nozzle 40 disposed on the lower surface of the inkjet head 3. As a result, the ink in the nozzle 40 whose viscosity has been increased (thickened) by drying is discharged, and the bubbles mixed in the ink flow path of the inkjet head 3 or in the further upstream sub tank 4 together with the ink. It is possible to recover the droplet ejection performance of the inkjet head 3 by discharging from the nozzle 40.

  In the present embodiment, as shown in FIG. 1, the suction cap 13 includes a first cap portion 13a that covers the nozzle 40 that ejects black ink, and three color inks (yellow ink, magenta ink, and And a second cap portion 13b that covers the nozzles 40 that eject cyan ink), and the first cap portion 13a and the second cap portion 13b are separated from each other. The first cap portion 13a and the second cap portion 13b are connected to the switching unit 15 via the two tubes 11a and 11b, respectively, and the switching unit 15 is further connected to the suction pump 14. Therefore, by switching the communication destination of the suction pump 14 between the first cap part 13a and the second cap part 13b by the switching unit 15, the nozzle 40 for ejecting black ink and the nozzle 40 for ejecting color ink are switched. The ink can be sucked by selecting either one of them.

  Next, the inkjet head 3 will be described. FIG. 2 is a vertical sectional view of a part of the inkjet head 3. As shown in FIG. 2, the inkjet head 3 includes a flow path unit 22 in which an ink flow path including a nozzle 40 and a pressure chamber 34 is formed, and a flow path unit by applying pressure to the ink in the pressure chamber 34. And a piezoelectric actuator 23 for ejecting ink from the 22 nozzles 40.

  The flow path unit 22 includes a cavity plate 30, a base plate 31, and a manifold plate 32 formed of a metal material such as stainless steel, and a nozzle formed of an insulating material (for example, a polymer synthetic resin material such as polyimide). A plate 33 is provided, and these four plates 30 to 33 are joined in a laminated state.

  A pressure chamber 34 is formed in the cavity plate 30. A plurality of pressure chambers 34 are provided side by side in the direction perpendicular to the plane of FIG. The base plate 31 has communication holes 35 and 36 that communicate with the pressure chambers 34, respectively. The manifold plate 32 is formed with a manifold 37 that communicates with the plurality of pressure chambers 34 via the communication holes 35 and a communication hole 39 that communicates with the communication holes 36. Furthermore, a plurality of nozzles 40 are formed on the nozzle plate 33, and the plurality of nozzles 40 are arranged in the direction perpendicular to the paper surface of FIG. A plurality of individual ink flow paths 41 extending from the manifold 37 to the nozzles 40 through the pressure chambers 34 are formed in the flow path unit 22.

  The piezoelectric actuator 23 includes a metal diaphragm 50 bonded to the upper surface of the flow path unit 22 so as to cover the plurality of pressure chambers 34, a piezoelectric layer 51 disposed on the upper surface of the diaphragm 50, and the piezoelectric layer 51. And a plurality of individual electrodes 52 formed on the upper surface.

  The metal diaphragm 50 is always held at the ground potential by the head driver 53. The piezoelectric layer 51 is made of a piezoelectric material mainly composed of lead zirconate titanate (PZT) which is a solid solution of lead titanate and lead zirconate and is a ferroelectric substance. It arrange | positions so that the pressure chamber 34 may be straddled. The plurality of individual electrodes 52 are respectively disposed in regions on the upper surface of the piezoelectric layer 51 facing the central portions of the plurality of pressure chambers 34. The plurality of individual electrodes 52 are supplied with either a ground potential or a predetermined drive potential different from the ground potential by the head driver 53.

  The operation of the piezoelectric actuator 23 during ink ejection will be described. When ejecting ink droplets from a certain nozzle 40, a driving potential is applied from the head driver 53 to the individual electrode 52 corresponding to the pressure chamber 34 communicating with the nozzle 40. Then, a potential difference is generated between the individual electrode 52 to which the driving potential is applied and the diaphragm 50 held at the ground potential, and an electric field parallel to the thickness direction is generated in the piezoelectric layer 51 sandwiched between the two. Here, when the polarization direction of the piezoelectric layer 51 is the same as the electric field direction, the piezoelectric layer 51 extends in the thickness direction and contracts in the plane direction. As the piezoelectric layer 51 contracts and deforms, the portion of the diaphragm 50 facing the pressure chamber 34 is deformed so as to be convex toward the pressure chamber 34 (unimorph deformation). At this time, the volume of the pressure chamber 34 decreases, the pressure of the ink inside the pressure chamber 34 increases, and ink is ejected from the nozzle 40 communicating with the pressure chamber 34.

  Next, the sub tank 4 that supplies ink to the inkjet head 3 will be described in detail. Since the structures of the four sub tanks 4a to 4d that respectively store the four color inks are basically the same, one of the sub tanks will be described below.

  FIG. 3 is a vertical sectional view of the sub tank 4. 4 is a cross-sectional view taken along line XX in FIG. FIG. 5 is a cross-sectional view taken along line YY of FIG. The sub tank 4 is formed of a synthetic resin material or the like. In the sub tank 4, an ink storage chamber 60 extending in the horizontal direction and a vertical communication with both the ink storage chamber 60 and the inkjet head 3 are provided. A flow path 61 is provided.

  The ink storage chamber 60 communicates with the ink cartridge 6 (see FIG. 1) via the tube 5 connected to the tube joint 20, and temporarily stores the ink supplied from the ink cartridge 6.

  The upper end portion of the vertical flow path 61 is located at substantially the same height as the ink outlet 65 of the ink storage chamber 60 extending in the horizontal direction, and the upper end portion of the vertical flow path 61 and the ink outlet of the ink storage chamber 60 are located. 65 communicates. Further, below the vertical channel 61 is a connecting portion 66 having a small diameter, and is connected to the inkjet head 3 at the lower end portion of the connecting portion 66. Note that a filter 63 is provided at a connection port of the inkjet head 3 with the sub tank 4 (connection portion 66) for removing dust and the like mixed in the ink flowing from the sub tank 4 to the inkjet head 3.

  The ink supplied from the ink cartridge 6 to the sub tank 4 via the tube 5 is temporarily stored in the ink storage chamber 60 and then flows out horizontally from the ink outlet 65 to the upper end of the vertical flow path 61. Further, in the vertical flow path 61, the ink flows downward, passes through the filter 63, and is supplied to the inkjet head 3.

  Further, in the present embodiment, a gas trap plate 72 (gas trap member) and a rotating shaft 71 screwed with a central portion of the gas trap plate 72 are provided in the vertical flow path 61 of the sub tank 4. As will be described later, the printer 1 of the present embodiment sucks ink from the plurality of nozzles 40 by the suction pump 14 in a state where the plurality of nozzles 40 arranged on the lower surface of the inkjet head 3 are covered with the suction cap 13. By doing so, it is possible to discharge the bubbles present in the sub tank 4 from the nozzle 40 together with the ink. The gas capturing plate 72 removes bubbles in the sub tank 4 (vertical flow path 61) when the carriage 2 is moved to the suction area where the cap 13 is located in order to perform ink suction by the suction pump 14. It is for making it transfer to the side (downstream side).

  As shown in FIGS. 3 to 5, the gas capturing plate 72 has a rectangular shape whose horizontal cross-sectional shape is slightly smaller than the rectangular vertical channel 61 and is disposed in the vertical channel 61. That is, as shown in FIG. 5, the projected area of the gas capturing plate 72 in the extending direction of the vertical flow path 61 (flow path extending direction) is based on a cross-sectional area in a plane orthogonal to the extending direction of the vertical flow path 61. Is also getting smaller.

  A rotating shaft 71 is screwed into the central portion of the gas capturing plate 72 in the horizontal plane. The rotating shaft 71 extends in the vertical direction at the center in the horizontal plane of the vertical channel 61. The tip of the rotary shaft 71 on the upper end side of the vertical flow path 61 extends upward through a through hole 64 formed in the sub tank 4, and the tip is fixed to the gear 73. That is, when the gear 73 rotates, the rotating shaft 71 also rotates in the same direction as the rotation of the gear 73. The rotating shaft 71 and the through hole 64 are sealed so that the ink in the vertical flow path 61 does not leak from the through hole 64.

  The tip of the rotary shaft 71 on the lower end side of the vertical flow path 61 extends to the upper end of the connection portion 66 of the vertical flow path 61. That is, as the rotation of the gear 73 causes the rotation shaft 71 to rotate, the gas capturing plate 72 moves along the extending direction of the rotating shaft 71 (the extending direction of the vertical flow path 61). It is arranged to be movable up and down from the upper end portion to the upper end portion of the connection portion 66. A recess 67 is formed at the upper end of the connection portion 66. Thereby, when the gas capture plate 72 has moved to the upper end portion of the connection portion 66, the upper end portion of the connection portion 66 is not sealed by the gas capture plate 72, and the interior of the connection portion 66 and the gas capture plate 72. The inside of the upper vertical flow path 61 communicates.

  The lower surface (downstream surface) of the gas capturing plate 72 has a bowl shape inclined toward the downstream side with respect to a horizontal plane (a direction orthogonal to the extending direction of the vertical flow path 61) from the center toward the outer periphery. I am doing. As a result, the bubbles located on the downstream side of the gas capturing plate 72 are lifted by buoyancy and are held on the lower surface of the gas capturing plate 72. At this time, since the lower surface of the gas capturing plate 72 has a bowl shape, the bubbles are easily guided to the center by buoyancy and are easily collected. That is, the gas capture plate 72 ensures the capture of bubbles. Further, even if the posture of the gas trap plate 72 is slightly inclined, the trapped bubbles will not escape unless the position outside the gas trap plate 72 in the vertical direction is tilted to a position higher than the center. Further, even when the posture of the gas trap plate 72 is inclined in the vertical direction and the position outside the gas trap plate 72 in the vertical direction is higher than the center, the tilt from the center to the outside is gentle. , Air bubbles are less likely to escape due to buoyancy.

  Further, a brush 74 (gas blocking member) formed of a large number of elastic members such as rubber is provided on an inner wall surface of the vertical flow path 61 on a portion (outer peripheral surface) facing the inner wall of the vertical flow path 61 of the gas trap plate 72. It is provided toward (horizontal direction). The rubber constituting the brush 74 is arranged at an interval that allows liquid such as ink to pass but blocks gas. The tip of the brush 74 is in contact with the inner wall of the vertical channel 61. That is, on the horizontal surface where the gas trap plate 72 is positioned in the vertical channel 61, the liquid that allows ink to pass only between the outer peripheral surface of the gas trap plate 72 and the inner wall surface of the vertical channel 61. A passage is constructed. Moreover, since the brush 74 is provided in this liquid channel, passage of gas is blocked | prevented. Further, since the brush 74 is made of an elastic member such as rubber, the inner wall is not damaged even if the tip of the brush 74 contacts the inner wall of the vertical flow path 61. In addition, the tip of the brush 74 is in contact with the inner wall of the vertical channel 61, and there is no gap between the tip of the brush 74 and the inner wall of the vertical channel 61, thereby further preventing the passage of gas.

  One end of two spring members 76 is connected to the upper surface of the gas capturing plate 72. The other ends of the two spring members 76 are connected to the inner wall of the upper end portion of the vertical flow path 61. The two spring members 76 are provided at positions symmetrical to the through hole 75 (see FIG. 5). When the gas capturing plate 72 is located on the upper end side of the vertical flow path 61, the two spring members 76 do not bias the gas capturing plate 72, and the gas capturing plate 72 does not support the vertical flow path 61. The urging force for pulling the gas capturing plate 72 toward the upper end side increases as it moves toward the lower end side. The two spring members 76 have the same length and spring constant. Thus, since the gas trap plate 72 is pulled to the upstream side of the vertical flow path 61 by the urging force of the two spring members 76, the posture can be stabilized in the horizontal direction without being tilted. Air bubbles trapped in 72 are difficult to escape.

  Further, when the rotating shaft 71 rotates, the gas trap plate 72 moves in the vertical direction without rotating due to the contact resistance between the tip of the brush 74 and the inner wall of the vertical flow path 61. Even if the brush 74 is not provided, the gas trap plate 72 rotates even if the rotary shaft 71 rotates as long as the gas trap plate 72 has such a size that the gas trap plate 72 cannot rotate in the vertical flow path 61. In the middle, it contacts the inner wall surface of the vertical flow path 61, and its rotational movement is obstructed, and it can move up and down with the rotation of the rotating shaft 71 while maintaining this state. Further, the inner wall of the vertical flow path 61 and the gas trap plate 72 have a concave portion and a convex portion, respectively, as rotation stoppers, and the rotation operation of the gas trap plate 72 accompanying the rotation of the rotary shaft 71 is achieved by engaging them. It may be inhibited.

  Next, the drive mechanism for moving the gas trap plate 72 in the extending direction of the vertical flow path 61 will be described in detail. FIG. 6 is an enlarged view of the vicinity of the suction region where the suction cap is located. FIG. 7 is a diagram showing the movement of the gas trap plate in the sub tank. As shown in FIG. 6, the four sub-tanks 4 a to 4 d described above are provided with gears 73 a to 73 d on their upper surfaces. The gears 73a to 73d mesh with adjacent gears. Further, the gear 73d meshes with a pinion gear 90 that is rotatably fixed to the upper surface of the carriage 2. Further, a rack gear 91 extending in the left-right direction than the length in the left-right direction of the suction cap 13 is provided at the right end portion of the guide shaft 17 located on the upper side in FIG.

  The rack gear 91 and the pinion gear 90 mesh with each other when the carriage 2 moves away from the printing area while moving toward the suction area. When the carriage 2 continues to move to the suction area, the pinion gear 90 meshed with the rack gear 91 starts to rotate counterclockwise. Then, the gear 73d meshed with the pinion gear 90 starts to rotate clockwise by the rotation of the pinion gear 90. Then, since the gears 73a to 73d are engaged with each other, the gear 73c starts to rotate counterclockwise, the gear 73b rotates clockwise, and the gear 73a starts rotating counterclockwise. That is, the four gears 73a to 73d rotate in conjunction with the movement of the carriage 2 to the suction area. As the four gears 73a to 73d rotate, the rotating shaft 71 rotates, and the gas capturing plate 72 moves in the extending direction of the vertical flow path 61.

  Next, the operation of the gas trap plate 72 will be described. As shown in FIG. 6, when the carriage 2 is located in the printing region (for example, position A), the gas trap plate 72 in the sub tank 4 moves in the vertical flow while the rack gear 91 and the pinion gear 90 are not engaged with each other. It waits at the upper end part of the path | route 61 (refer Fig.7 (a)). The position of the gas trap plate 72 is higher than the ink outlet of the ink storage chamber 60. Therefore, the air bubbles mixed in the ink supply flow path from the ink cartridge 6 to the ink jet head 3 rise upward due to the buoyancy, and in particular, the gas trapped at the upper end of the vertical flow path 61 formed in the sub tank 4. It tends to collect on the lower surface of the plate 72.

  When the carriage 2 moves from the printing area toward the suction area and moves to a predetermined position (for example, position B) in the suction area, the rack gear 91 and the pinion gear 90 are engaged with each other for the first time. As the pinion gear 90 rotates, the four gears 73a to 73d rotate as the pinion gear 90 continues to move in the same direction. Then, the rotating shaft 71 fixed to each of the four gears 73a to 73d rotates, and each gas capturing plate 72 in the sub tanks 4a to 4d moves downstream of the vertical flow path 61 while capturing the bubbles 86 on the lower surface. Start moving. At this time, the ink moves upstream from the liquid passage between the outer peripheral surface of the gas capturing plate 72 and the inner wall surface of the vertical flow path 61. That is, the ink can escape from the liquid passage to the upstream side and can be transferred to the downstream side while only the bubbles are captured by the gas capturing plate 72. Further, since each gas capturing plate 72 does not move when the carriage 2 is in the printing region, erroneous ejection is not performed during printing.

  When the carriage 2 moves to the suction region and stops, the rotation of the pinion gear 90 stops, and accordingly, the rotation of the gears 73a to 73d and the rotation shaft 71 also stops, and the gas capturing plate 72 is connected to the upper end portion of the connection portion 66. Stop at. At this time, the bubbles 86 transferred from the upstream side are captured on the lower surface of the gas capturing plate 72 (see FIG. 7B). With the gas capturing plate 72, a large amount of air bubbles 86 are transferred to the downstream side in advance at a time, and the suction pump 14 performs the ink suction operation described later from the nozzle 40. The bubble 86 is sucked and discharged from the nozzle 40. At this time, since the bubbles 86 can be moved to the nozzle 40 side by the gas capturing plate 72, the amount of ink discharged from the nozzles 40 is reduced as compared with the case where the bubbles 86 are discharged only by suction by the suction pump 14. be able to.

  Since the rotation directions of the gears 73a and 73c and the gears 73b and 73d are opposite to each other, the thread formed on the rotation shaft 71 fixed to the gears 73a and 73c is the rotation shaft fixed to the gears 73b and 73d. When the carriage 2 is moved to the suction region, the gas capturing plate 72 is not connected to the vertical flow path 61 regardless of which gear 73a to 73d rotates. It is configured to move downstream. That is, in the present embodiment, the pinion gear 90, the rack 91, the gears 73a to 73d, the rotating shaft 71, and the gas capturing plate 72 constitute liquid transfer means, and further, the pinion gear 90, the rack 91, the gears 73a to 73d, and the rotating shaft. 71 constitutes a driving means.

  Next, the control device 8 that controls the entire printer 1 will be described. FIG. 8 is a block diagram showing an electrical configuration of the printer 1. A control device 8 shown in FIG. 8 includes a central processing unit (CPU), a ROM (Read Only Memory) in which various programs and data for controlling the overall operation of the printer 1 are stored, A RAM (Random Access Memory) or the like for temporarily storing data processed by the CPU is provided.

  Further, the control device 8 includes a recording control unit 81 and a suction control unit 82. The recording control unit 81 conveys the carriage drive motor 19 that reciprocates the carriage 2 (see FIG. 1), the head driver 53 of the inkjet head 3, and the recording paper P based on data input from an input device 80 such as a PC. In this case, a conveyance motor 83 included in a sheet conveyance mechanism (not shown) is controlled to record an image or the like on the recording sheet P. The suction controller 82 (suction controller) controls the cap drive motor 84 and the suction pump 14 that drive the suction cap 13 up and down to suck ink from the plurality of nozzles 40 of the inkjet head 3. It is what makes you do.

  The ink suction operation of the suction pump 14 controlled by the suction controller 82 will be specifically described. Bubbles (air) may be mixed in the ink supply channel including the sub tank 4 from the ink cartridge 6 to the inkjet head 3 due to various factors. For example, when the ink cartridge 6 is replaced, air is likely to enter from the end of the tube 5 connected to the ink cartridge 6. In addition, it is sufficiently conceivable that air gradually enters from a connection portion between the sub tank 4 and the tube 5 over a long period of time. The bubbles mixed in the ink supply channel in this way gather at the upper end of the sub tank 4 due to the buoyancy and grow into large bubbles. If the bubbles flow into the inkjet head 3 together with the ink from the sub tank 4, there is a possibility that a droplet ejection failure occurs in the inkjet head 3.

  Accordingly, when the replacement of the ink cartridge 6 is detected by the cartridge detection sensor 85 provided in the holder 7 (see FIG. 1), or when it is determined that the bubbles in the sub tank 4 have not been discharged over a long period of time, the suction control unit 82 causes the suction pump 14 to perform a suction operation to discharge the bubbles in the sub tank 4 from the nozzle 40 together with the ink.

  Specifically, after the recording control unit 81 moves the carriage 2 to the suction region by the carriage drive motor 19, the suction control unit 82 moves the suction cap 13 upward by the cap drive motor 84, and the suction cap 13 is ink-jet. In the state where the plurality of nozzles 40 of the head 3 are covered, the suction pump 14 is caused to suck ink. Then, the bubbles in the sub tank 4 are drawn into the inkjet head 3 together with the ink, and the bubbles are discharged from the nozzle 40 through the ink flow path in the inkjet head 3.

  By the way, if the ink is sucked from the nozzle 40 by the suction pump 14, in order to discharge the bubbles attached to the inner wall of the flow path away from the nozzle 40 such as the upper end portion of the sub tank 4, suction is performed with a considerably strong suction force. In addition, the amount of ink discharged from the nozzle 40, that is, the amount of ink that is wasted is increased along with the bubbles.

  However, in the printer 1 of the present embodiment, as described above, the gas capturing plate 72 is disposed in the vertical flow path 61 of the sub tank 4. The gas trap plate 72 allows the bubbles captured by the gas trap plate 72 in the sub tank 4 to be transferred to the inkjet head 3 during the ink suction operation.

  Here, a series of flows up to the suction operation will be described. First, the carriage 2 is moved from the printing area to the suction area in order to discharge the bubbles 86 in the sub tank 4 by the suction control unit 82. When the carriage 2 is positioned in the printing area, the gas capturing plate 72 is waiting at the upper end of the vertical flow path 61. When the carriage 2 moves outside the printing area, the rack 91 and the pinion gear 90 mesh with each other, and the carriage 2 moves to the suction area, whereby the gears 73a to 73d are rotated with the rotation of the pinion gear 90. And the rotating shaft 71 rotates, and each gas trapping plate 72 in the sub-tanks 4a to 4d starts moving to the downstream side of the vertical flow path 61 while trapping the bubbles 86 on the lower surface thereof.

  When the carriage 2 moves to the suction region and stops, the rotation of the pinion gear 90 stops, and accordingly, the rotation of the gears 73a to 73d and the rotation shaft 71 also stops, and the gas capturing plate 72 is connected to the upper end portion of the connection portion 66. Stop at. At this time, the bubbles 86 transferred from the upstream side are captured on the lower surface of the gas capturing plate 72. The suction pump 14 performs the suction operation of ink from the nozzle 40 in a state where a large amount of the bubbles 86 are transferred to the downstream side in advance by the gas capturing plate 72 at a time. 86 is sucked and discharged from the nozzle 40.

Further, when the carriage 2 is moved to the suction region, the gas capturing plate 72 is moved downstream in conjunction with the movement of the carriage 2, so that an actuator for moving the gas capturing plate 72 is necessary. And not.

  Furthermore, since the rack 91 and the pinion gear 90 mesh with each other after the inkjet head 3 has moved out of the printing area, and the gas capture plate 72 starts to move downstream, when the carriage 2 is moved during a normal printing operation, It is possible to prevent the gas capturing plate 72 from moving in the flow path extending direction and the ink flow in the ink supply flow path from becoming unstable.

  Next, modified embodiments in which various modifications are added to the embodiment will be described. However, components having the same configuration as in the above embodiment are given the same reference numerals and description thereof is omitted as appropriate.

  In the present embodiment, a gap is formed between the side surface of the gas capturing plate 72 and the inner wall surface of the vertical flow path 61, and this constitutes a liquid passage, but the side surface of the gas capturing plate 72 is It is slidable along the inner wall surface of the vertical flow path 61, and a large number of through holes and notches are formed in the surface of the gas capturing plate 72. May be. At this time, the through holes and the cutouts may have any diameter and size that does not destroy the surface tension of the bubbles (does not allow the bubbles to pass) and allows ink to pass through.

  In addition, the brush 74 may not be provided when the liquid passage is a minute passage that allows only the ink to pass to the extent that the surface tension of the bubble is not destroyed (the bubble does not pass).

  Furthermore, the number of spring members 76 is not limited to two, and more spring members may be provided in order to stabilize the posture of the gas capturing plate 72. Further, the spring member 76 may have an urging force that pushes the gas capturing plate 72 toward the lower end side of the vertical flow path 61. That is, any biasing force may be applied evenly to the horizontal surface of the gas trap plate 72 so that the posture of the gas trap plate 72 is stabilized. Therefore, when the diameter of the rotary shaft 71 is large and the area of the horizontal cross-sectional area of the rotary shaft 71 is larger than the horizontal cross-sectional area of the gas trap plate 72, the posture of the gas trap plate 72 is likely to be stable. The spring member may not be provided.

  In addition, when the carriage 2 is moved to the suction region, the gas capturing plate 72 is moved downstream in conjunction with the movement of the carriage 2, but as shown in FIG. Alternatively, an actuator 150 may be separately provided, and the gas trap plate 72 may be moved by rotating the rotary shaft 71 by a drive different from the movement of the carriage 2. At this time, first, after the carriage 2 is moved to the suction region, the suction control unit 82 rotates the rotation shaft 71 by the actuator 150, and the gas capturing member 72 is moved from the upper end portion of the vertical flow path 61 to the upper end portion of the connection portion 66. And the suction pump 14 performs a suction operation.

  In addition, the brush 74 may be composed of a large number of rigid members such as a wire instead of a large number of elastic members such as rubber. In this case, the inner wall of the vertical flow path 61 is not damaged, and the surface tension of the bubbles is reduced. It is preferable that the gap between the tip of the brush and the inner wall of the vertical flow path is made minute so that only ink is allowed to pass so as not to break the air (pass air bubbles).

  Furthermore, in the ink supply flow path from the ink cartridge to the ink jet head, the flow path portion where the gas capturing plate is provided is not necessarily a flow path extending in the vertical direction. That is, even when a gas trap plate is provided in a channel inclined at an angle with respect to the vertical direction, or even when a gas trap plate is provided in a horizontal channel extending in the horizontal direction, If the plate can move along the flow path direction, the effect of transferring bubbles in the flow path can be obtained.

  In the embodiment described above, the present invention is applied to an ink jet printer that records an image or the like by ejecting ink onto recording paper. However, the application target of the present invention is not limited to such a printer. The present invention can be applied to various droplet ejecting apparatuses that eject various types of liquids onto a target depending on the application.

1 is a plan view illustrating a schematic configuration of a printer according to an embodiment. It is a vertical sectional view of a part of an inkjet head. It is a vertical sectional view of a sub tank. It is sectional drawing along the XX line of FIG. It is sectional drawing along the YY line of FIG. It is an enlarged view near the suction region where the suction cap is located. It is a figure which shows the movement of the gas capture board in a subtank. FIG. 2 is a block diagram schematically illustrating an electrical configuration of a printer. It is a block diagram which shows roughly the electric structure of the printer in a modification.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Printer 2 Carriage 3 Inkjet head 4 Sub tank 5 Tube 8 Control apparatus 13 Cap 14 Suction pump 40 Nozzle 60 Ink storage chamber 61 Vertical flow path 72 Gas capture plate 74 Brush 76 Spring member 82 Suction control part 90 Pinion gear 91 Rack

Claims (8)

A droplet ejection head having a nozzle for ejecting droplets;
A liquid supply flow path for supplying a liquid to the droplet ejection head;
Suction means for sucking the liquid in the liquid supply channel from the nozzle of the droplet discharge head;
A gas transfer means for capturing the gas in the liquid supply flow path during the suction operation of the suction means and moving the captured gas toward the nozzle on the downstream side;
With
The gas transfer means includes
And a gas trapping member to which the liquid is movably disposed in a flow path extending direction of the supply passage smell Teso, to capture gas in the liquid supply passage,
Driving means for moving the gas capturing member in the flow path extending direction;
When the gas trapping member moves in the channel extending direction between the gas trapping member itself or between the gas trapping member and the inner wall surface of the liquid supply channel, the liquid exceeds the gas trapping member. A liquid droplet ejecting apparatus characterized in that a liquid passage is formed.   The downstream surface of the gas trapping member is inclined toward the downstream side with respect to a plane orthogonal to the flow path extending direction from the center toward the outer periphery. Droplet ejector. The projected area in the flow channel extending direction of the gas capturing member is smaller than the cross-sectional area in a plane orthogonal to the flow channel extending direction of the liquid supply flow channel,
3. The droplet ejecting apparatus according to claim 1, wherein the liquid passage is formed between an outer peripheral surface of the gas capturing member and an inner wall surface of the liquid supply channel.   A portion of the gas capturing member facing the liquid passage is provided with a brush-like gas blocking member that allows passage of liquid in the liquid passage and can block passage of gas. The liquid droplet ejecting apparatus according to claim 1.   The liquid droplet according to claim 1, further comprising a spring member that urges the gas trapping member in the flow path extending direction to stabilize the posture of the gas trapping member. Injection device. The liquid supply channel extends in the vertical direction with a liquid storage chamber that stores liquid, and is connected to a liquid outlet of the liquid storage chamber at an upper end portion thereof, and the liquid droplet ejection at the lower end portion thereof. A vertical flow path connected to the head,
The gas capturing member is disposed so as to be movable in the vertical direction in the vertical flow path,
When the suction operation by the suction means is not performed and the gas trapping member is waiting at the upper end portion in the vertical flow path, the position of the gas trapping member is more than the liquid outlet of the liquid storage chamber. The liquid droplet ejecting apparatus according to claim 1, wherein the liquid droplet ejecting apparatus is at a high position. The droplet ejection head is mounted on a carriage that can reciprocate along one direction, and is configured to eject droplets from the nozzle when in a predetermined droplet ejection region,
The suction unit has a cap that is disposed in a suction region outside the one direction with respect to the droplet ejecting region and can cover the nozzle of the droplet ejecting head;
When the carriage moves to the suction area where the cap is disposed in order to perform the suction operation by the suction means, the drive means moves the carriage to move the gas capturing member in conjunction with the movement of the carriage. The liquid droplet ejecting apparatus according to claim 1, wherein the liquid droplet ejecting apparatus is configured to move along a flow path extending direction.   When the droplet ejecting head moves out of the droplet ejecting area together with the carriage, power is transmitted from the carriage to the driving unit for the first time, and the gas capturing member driven by the driving unit moves downstream. The liquid droplet ejecting apparatus according to claim 7, wherein the liquid droplet ejecting apparatus starts to move.

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