JP2010188562A - Liquid ejecting head and liquid ejecting apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a liquid ejecting head 7 and a liquid ejecting apparatus A which can efficiently suck an unnecessary liquid at each time ejecting and non-ejecting the liquid while being reduced in size. <P>SOLUTION: The liquid ejecting head 7 includes a head body 91 and a suction means. The head body is constructed by including a pressure chamber 11 which stores the liquid, a nozzle plate 13 with a nozzle surface where the leading end of a nozzle 12 that communicates with the pressure chamber 11 is opened, and a pressure applying means 14 which applies a pressure to the liquid in the pressure chamber 11 to discharge the liquid in the pressure chamber 11 through the nozzle 12. The suction means has a suction opening 18a located at a position near the opening of the nozzle 12 and sucks the unnecessary liquid present on the periphery of the nozzle 12 opening at each time ejecting and non-ejecting the liquid through the suction opening 18a. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a liquid discharge head that discharges droplets and a liquid discharge apparatus including the liquid discharge head.

  Ink jet technology for ejecting ink droplets onto recording paper has been used in manufacturing processes in various fields including the electronics field in recent years. That is, by discharging a liquid material from a liquid discharge head, patterns are formed and uniform thin films are formed in various device manufacturing processes. The liquid material used for such pattern formation has a property of high viscosity as compared with the ink used for normal recording. Therefore, when discharging liquid material, apart from the main droplet, satellite droplets that fly late from the main droplet at a relatively slow speed, and floating droplets that fly in various directions with no fixed flying direction (Mist) is likely to occur. Such satellite droplets and floating droplets cause a decrease in landing accuracy and instability of the droplet amount, thereby reducing the reliability of the liquid discharge head.

For example, Patent Document 1 discloses that an inkjet recording apparatus that forms an image by ejecting ink onto recording paper includes a suction unit that sucks such satellite droplets and floating droplets. This suction means includes a suction unit formed with a suction port for sucking satellite droplets and the like. When the ink is not ejected, the suction unit is disposed so as to contact the nozzle surface of the inkjet head, and residual ink near the nozzle surface is arranged. On the other hand, when ejecting ink, the suction unit is moved to a side position of the head to suck satellite drops or the like.
JP 2007-216420 A

  The suction unit disclosed in Patent Document 1 uses the same suction unit to suck unnecessary droplets when ink is ejected and when ink is not ejected. Since it is positioned at a side position of the head, the suction port of the suction unit is far away from the nozzle opening of the inkjet head. For this reason, there is a problem that satellite droplets and floating droplets generated in the vicinity of the nozzle opening when ink is ejected cannot be sucked effectively. In addition, a mechanism for moving the suction unit separate from the ink jet head relative to the ink jet head during ink ejection and non-ejection is required, resulting in an increase in the size of the liquid ejection apparatus.

  The present invention has been made in view of the above points, and an object of the present invention is to efficiently suck unnecessary liquid at each time of discharging and non-discharging of the liquid while reducing the size. It is an object to provide a liquid discharge head and a liquid discharge apparatus.

  The liquid discharge head includes a pressure chamber that stores liquid, a nozzle plate having a nozzle surface that is open at a tip of a nozzle that communicates with the pressure chamber, and the pressure through the nozzle by applying pressure to the liquid in the pressure chamber. A head body including pressure applying means for discharging the liquid in a pressure chamber, and a suction port located in the vicinity of the nozzle opening, and when the liquid is discharged and not discharged through the suction port In each of the above, suction means for sucking unnecessary liquid around the nozzle opening is provided.

  By arranging the suction port of the suction means in the vicinity of the nozzle opening, satellite droplets and floating droplets can be efficiently sucked when droplets are ejected through the nozzle, and the nozzle surface is also ejected when droplets are not ejected. Residual droplets adhering to can be efficiently sucked. As a result, it is possible to prevent droplets from being scattered, improve droplet landing accuracy, stabilize the discharge speed and the amount of droplets, and improve the reliability of the liquid discharge head.

  This configuration also eliminates the need for a configuration for changing the position of the suction port, so that the liquid discharge head can be reduced in size accordingly.

  A plurality of the suction ports may be arranged so as to be symmetric with respect to the central axis of the nozzle. In addition, a circumferential suction port may be disposed around the nozzle.

  In this way, the suction force by each suction port acts equally on the main droplet flying along the central axis of the nozzle, and the nozzle does not adversely affect the flight of the main droplet. Satellite droplets and floating droplets that do not fly along the central axis of the can be efficiently aspirated.

  In the suction unit, a suction passage including the suction port may be formed in the head body.

  By doing so, the liquid discharge head can be further reduced in size, and the structure can be simplified, which is advantageous in terms of reducing the manufacturing cost.

  The suction port may be defined by a nozzle surface of the nozzle plate. This improves the accuracy of the relative position of the suction port with respect to the nozzle opening.

  The liquid discharge head may further include suction force variable means for changing the suction force of the suction means.

  For example, if the suction force is changed between when a droplet is ejected and when it is not ejected, satellite droplets or floating droplets are aspirated when the droplet is ejected, and the residue adhered to the nozzle surface when the droplet is not ejected. Droplet aspiration is optimized respectively.

  In addition, when the droplet is discharged, if the suction force is changed between the start of discharge and the end of discharge, the satellite droplets generated after the main droplets fly without affecting the main droplets. In addition, efficient suction can be realized for floating droplets.

  Furthermore, when there are a plurality of suction ports, the suction force can be balanced by adjusting the suction forces of the suction ports to be equal to each other.

  On the nozzle surface of the nozzle plate, a lead-out path that extends from the nozzle opening toward the suction port and guides the unnecessary liquid to the suction port may be formed.

  By doing so, it is possible to efficiently suck the liquid droplets adhering to the nozzle surface by moving them to the suction port along the outlet path.

  It is good also as providing the sealing member which forms the sealed space which the opening of the said nozzle communicates by mounting | wearing with the said head main body, and the suction port of the said suction means is opening in the said sealed space.

  In this way, by forming a sealed space with the sealing member, unnecessary residual droplets adhering to the nozzle surface can be efficiently sucked. At the same time, it is possible to fill the empty pressure chamber with the liquid by using the suction force of the suction means. For this reason, for example, in order to fill the liquid in the empty pressure chamber, it is possible to omit means for making the inside of the tank for storing the liquid positive pressure, and the configuration of the liquid ejection device is simplified.

  Since the liquid ejection apparatus includes the liquid ejection head described above, unnecessary liquid droplets are efficiently sucked in each of the liquid ejection time and the non-ejection time to prevent the liquid droplets from being scattered. The landing accuracy can be improved, the ejection speed and the droplet amount can be stabilized, the reliability of the liquid ejection head can be improved, and the size can be reduced.

  As described above, according to the present invention, it is possible to efficiently suck unnecessary liquid droplets at the time of discharging and non-discharging liquid while improving the reliability of the liquid discharge head. can do.

  Hereinafter, embodiments will be described with reference to the drawings. In addition, the following description of preferable embodiment is an illustration essentially and does not intend restrict | limiting an application thing or a use.

  FIG. 1 shows a schematic configuration of the liquid ejection apparatus A. The liquid discharge apparatus A includes a liquid discharge head 7 having a head main body (see FIG. 2 and the like) and a stage 31 that supports the recording material 4. The liquid discharge head 7 is reciprocated in the main scanning direction (X direction shown in FIG. 1) by the head moving device 2 supported on the apparatus base 6, and the stage 31 is also moved on the stage supported on the apparatus base 6. The apparatus 3 reciprocates in the sub-scanning direction (Y direction shown in FIG. 1). The head moving device 2 includes a carriage 7 a that supports the liquid ejection head 7. The carriage 7a is guided by a carriage shaft 7b extending in the main scanning direction, and reciprocates in the main scanning direction by a driving source (for example, a motor) (not shown).

  The stage moving device 3 includes two stage shafts 32 and 32 that are arranged at a predetermined interval in the main scanning direction and extend in the sub scanning direction, respectively. The stage 31 is guided by these stage shafts 32 and 32 and reciprocates in the sub-scanning direction by a driving source (for example, a motor) (not shown).

  With this configuration, the liquid ejection apparatus A ejects a liquid material from the liquid ejection head 7 (head body 91) toward the recording material 4 while relatively moving the liquid ejection head 7 and the recording material 4 on the stage 31. Then, a desired pattern or a uniform thin film is formed on the recording material 4.

  As shown in FIG. 2, the head main body 91 includes a pressure chamber 11 that stores a liquid material, a nozzle plate 13 in which one nozzle 12 that communicates with the pressure chamber 11 is formed, and a pressure applied to the liquid material in the pressure chamber 11. , And an actuator 14 for discharging the liquid material in the pressure chamber 11 through the nozzle 12.

  The nozzle plate 13 is a plate-like member made of, for example, stainless steel, and the nozzle 12 is formed so as to penetrate the nozzle plate 13 in the plate thickness direction. In this example, the nozzle 12 has a tapered shape in which the diameter decreases from the base end (upper end in the upper diagram in FIG. 2) to the distal end (lower end in the upper diagram in FIG. 2). It may be a straight shape. The diameter of the tip opening of the nozzle 12 may be set to about φ5 to 300 μm, for example. The lower surface of the nozzle plate 13 is a nozzle surface where the tip of the nozzle 12 is opened, and the nozzle surface is preferably subjected to a water repellent treatment from the viewpoint of liquid material ejection stability.

  On the upper surface of the nozzle plate 13, an elastic partition member 15 that partitions the side surface of the pressure chamber 11 is disposed so as to surround the proximal end opening of the nozzle 12. As will be described later, the elastic partition member 15 is a member that elastically expands and contracts as the actuator 14 is driven to change the volume of the pressure chamber 11. For example, the elastic partition member 15 has a circular hole at its center. It is formed in an annular shape. The elastic partition member 15 may be formed of, for example, a solvent-resistant rubber, specifically, fluorine rubber, silicon rubber, or the like in consideration of corrosion resistance against the liquid material.

  The actuator 14 is disposed on the upper surface of the elastic partition member 15, and an adhesive layer 15 a that joins the nozzle plate 13 and the actuator 14 to each other is provided so as to surround the outer peripheral surface of the elastic partition member 15. The adhesive layer 15 a is also configured to restrict the elastic partition member 15 from being deformed to escape toward the outside of the pressure chamber 11 when the elastic partition member 15 is elastically deformed.

  The actuator 14 is made of a laminated piezoelectric material, and one end (lower end) in the stacking direction is joined to the upper surface of the elastic partition member 15 and the other end (upper end) is fixed to the actuator holding member 16. . The actuator 14 is also formed with a through hole formed so as to penetrate in the thickness direction so as to be coaxial with the central axis of the nozzle 12, and in the through hole, as described later, a liquid is placed in the pressure chamber. A supply pipe 20 for supplying the water is inserted. The actuator 14 expands and contracts in the vertical direction in the upper diagram of FIG. 2 when a voltage is applied to electrodes (not shown in FIG. 2) (see arrows in FIG. 2). As the actuator 14 is driven, the elastic partition member 15 expands and contracts in the vertical direction in the upper diagram of FIG.

  The actuator holding member 16 is a plate-like member, and as described above, the actuator 14 is joined to the lower surface thereof, thereby holding the integrated body of the actuator 14, the elastic partition member 15 and the nozzle plate 13. The actuator holding member 16 is also formed with a through hole for inserting the supply pipe 20 in the center position thereof in the thickness direction.

  The actuator holding member 16 is fixed to the exterior member 17. The exterior member 17 is a substantially rectangular block member, and an upper end surface of the exterior member 17 is joined to the head holding plate 19. A recess 17a that opens to the lower surface is formed inside the exterior member 17, and the actuator holding member 16 is fixed to the upper wall in the recess 17a. As a result, the integrated body of the actuator 14, the elastic partition member 15, and the nozzle plate 13 is disposed in the recessed portion 17a.

  The exterior member 17 is also formed with a through hole extending in the vertical direction at the center position, and a supply pipe 20 extending in the vertical direction is disposed in the through hole. A lower end portion of the supply pipe 20 is disposed in the through hole of the actuator holding member 16 and the through hole of the actuator 14, and the lower end surface thereof is joined to the upper surface of the elastic partition member 15. The upper surface of the pressure chamber 11 is partitioned by the lower end surface of the supply pipe 20. The inner hole of the supply pipe 20 is opened at each of the upper and lower ends of the supply pipe 20, whereby the inner hole communicates with the pressure chamber 11. The upper end of the supply pipe 20 also passes through the head holding plate 19 and is disposed so as to protrude from the upper surface of the head holding plate 19. As shown in FIG. The supply tank 42 is connected.

  The exterior member 17 is also formed with suction passages 18 at both side positions sandwiching the recessed portion 17a. Each suction passage 18 is formed to extend in the vertical direction, and is bent at the lower end thereof toward the recessed portion 17a, and the bent end opens on the side wall in the recessed portion 17a. . As will be described later, this opening functions as a suction port 18a for sucking unnecessary liquid around the nozzle opening at the time of discharging and not discharging the liquid, and this suction port 18a. 2 is located at a height position corresponding to the height of the nozzle surface of the nozzle plate 13 as shown in the upper diagram of FIG. 2, and with respect to the central axis of the nozzle 12 as shown in the lower diagram of FIG. Are located on both sides of the opening of the nozzle 12 so as to be symmetrical. In this way, each suction port 18a is positioned in the vicinity of the opening of the nozzle 12, and is configured to perform suction in a direction perpendicular to the droplet discharge direction (the downward direction in the upper diagram of FIG. 2). ing.

  Further, suction pipes 21, 21 arranged through the head holding plate 19 are attached to the upper portion of the exterior member 17 so as to extend in the vertical direction. It communicates with the upper end of the passage 18. As shown in FIG. 3, a suction tank 46 is connected to the upper end of the suction pipe 21 via a suction tube 45.

  FIG. 3 shows a configuration of a liquid supply system and a liquid suction system provided for the head main body 91. The liquid supply system includes a supply tank 42 and a supply pump 43 (air pump) as liquid supply means. The supply tank 42 is a tank that stores a liquid material to be supplied into the pressure chamber 11, and is connected to the supply pump 43 through the air supply pipe 44 and is supplied to the head main body 91 through the supply tube 41. 20 is connected. The air supply pipe 44 connected to the supply pump 43 is opened in the gas phase portion in the supply tank 42, while the supply tube 41 connected to the supply pipe 20 is made of the liquid material in the supply tank 42. Open in the area. The supply tank 42 is switched between a positive pressure state (a positive pressure state with respect to the pressure chamber 11) and a negative pressure state (a negative pressure state with respect to the pressure chamber 11) according to the operation of the supply pump 43. . In other words, when the empty pressure chamber 11 is filled with liquid, the inside of the supply tank 42 is brought into a positive pressure state, while when the head main body 91 is driven (when liquid is discharged), the inside of the supply tank 42 is negative. Pressure. The supply tank 42 may be switched between a positive pressure state and a negative pressure state by moving the height position of the supply tank 42 up and down relative to the height position of the pressure chamber 11. In this case, the supply pump 43 can be omitted.

  In contrast, the liquid suction system includes a suction tank 46 and a suction pump 47 (air pump) as a liquid suction means. As will be described later, the suction tank 46 is a tank that stores unnecessary liquid droplets collected from the head main body 91, and is connected to the suction pump 47 via the air suction pipe 48. The inside of the suction tank 46 is brought into a negative pressure state according to the operation of the suction pump 47. The suction tank 46 is also connected to the suction pipe 21 of the head main body 91 via the suction tube 45, and the suction tube 45 is branched into two in the middle of the suction tank 45 and connected to the pair of suction pipes 21 and 21, respectively. ing. The means for bringing the suction tank 46 into a negative pressure state is not limited to an air pump, and air suction by a liquid pump or a vacuum pump may be employed. Further, the suction tank 46 may be in a negative pressure state by using an appropriate means without being limited to the pump. Furthermore, the suction tank 46 can be omitted.

  Next, the operation of the head main body 91 having the above configuration will be described. The actuator 14 is expanded and contracted by applying a predetermined voltage (for example, 20 V) to the actuator 14 while the pressure chamber 11 and the nozzle 12 are filled with a liquid material, and releasing the voltage application. Deform (see arrow in the figure). As the actuator 14 expands and contracts, the elastic partition member 15 expands and contracts, and pressure is applied to the liquid material in the pressure chamber 11. Then, the liquid material is pushed out from the nozzle 12 and ejected as droplets (main droplets) toward the recording material 4, and the droplets adhere to the upper surface of the recording material 4 in the form of dots. At the same time, the liquid material is replenished from the supply tank 42 through the supply pipe 20 into the pressure chamber 11. When the liquid (droplet) is discharged, the supply tank 42 is in a predetermined negative pressure state by the operation of the supply pump 43. In the configuration in which the pressure chamber 11 is formed by the elastic partition member 15 that is elastically deformed as described above, a high pressure can be applied to the liquid material in the pressure chamber 11. This is suitable for discharging a liquid material.

  At the time of discharging the liquid droplets, the suction pump 47 is also operated to thereby perform suction through each suction port 18a. Accordingly, unnecessary droplets such as satellite droplets and floating droplets generated after the main droplets fly from the nozzle surface are sucked through the suction port 18a and collected in the suction tank 46. As a result, it is possible to prevent droplets from scattering, improve the landing position accuracy, and stabilize the discharge speed and droplet amount.

  Here, since the suction port 18a is positioned in the vicinity of the tip opening of the nozzle 12, it is possible to efficiently suck satellite droplets and floating droplets, and the pair of suction ports 18a and 18a are formed of nozzles. 12 are arranged symmetrically with respect to the central axis of 12 and the suction directions are set to be opposite to each other, so that the suction force cancels out against the main droplet flying along the central axis of the nozzle 12. In addition, adverse effects on the discharge of main droplets are avoided. This improves the landing accuracy of the main droplet. On the other hand, satellite droplets and floating droplets that are displaced from the central axis of the nozzle 12 are reliably sucked through any one of the suction ports 18a.

  The suction pump 47 is continuously operated even during non-ejection between the ejection of droplets, and the suction through the suction port 18a is continued. As a result, the remaining droplets adhering to the vicinity of the nozzle 12 after the droplets are discharged are sucked and removed through the suction port 18a. In this way, when the droplet is discharged next time, there is no residual droplet in the vicinity of the nozzle 12, so that the landing position accuracy is improved and the discharge speed and the droplet amount are stabilized. In particular, when the driving frequency of the head main body 91 is low and the time interval between ejection of droplets is relatively long, small droplets, dust, etc. are likely to be adsorbed on the nozzle surface due to static electricity or the like. By performing suction between the discharge of liquid droplets as described above, it is possible to effectively remove liquid droplets and dust on the nozzle surface, which is effective in stabilizing discharge performance. It is.

  Further, even when the head main body 91 is positioned at the retracted position, for example, when the liquid droplet is not discharged, the suction pump 47 is appropriately operated to adhere to the nozzle surface in preparation for the next liquid droplet discharge. It is desirable to remove residual droplets.

  Furthermore, suction is performed by operating the suction pump 47 also when filling the empty pressure chamber 11 with a liquid material (that is, when liquid droplets are not ejected). As described above, when the liquid is filled in the empty pressure chamber 11, the liquid material is sent into the pressure chamber 11 by making the inside of the supply tank 42 a positive pressure. Will leak out. Thus, when the liquid material is filled, excess liquid material adheres to the nozzle surface. The adhering liquid material is removed by being sucked through the suction port 18a. As a result, the discharge accuracy of the liquid material is improved. It can improve.

  As in these cases, when sucking a droplet attached to the nozzle surface, the droplet moves along the nozzle surface to the suction port 18a and is sucked from there. By arranging the pair of suction ports 18a, 18a on both sides of the opening of the nozzle 12, it is avoided that the liquid droplet is sucked into the suction port 18a across the opening of the nozzle 12. Thereby, contamination of the opening of the nozzle 12 is avoided, and the ejection accuracy of the head main body 91 can be maintained with high accuracy.

Here, the opening area of the suction port 18a may be set to, for example, 100 μm ^{2 to 1} mm ² , and the suction pressure is preferably set to, for example, −0.1 to −70 kPa.

  In the head main body 91, the suction passage 18 and the suction port 18a are formed in the head main body 91, which is advantageous in arranging the suction port 18a in the vicinity of the opening of the nozzle 12, and the head main body 91. This is also advantageous in terms of downsizing. Further, since the configuration of the head main body 91 is simplified, the manufacturing cost can be reduced.

  The number of suction ports provided in the head main body 91 is not particularly limited, and the number of suction ports may be one or three or more. When setting a plurality of suction ports, it is preferable to arrange the suction ports so as to be symmetric with respect to the central axis of the nozzle 12.

  Hereinafter, various modifications will be described with reference to the drawings. In the following description, the same components as those of the head main body 91 shown in FIG. 2 are denoted by the same reference numerals, and the description thereof may be omitted as appropriate.

  First, FIG. 4 shows a modification related to the configuration of the suction passage 18, and the head body 92 is configured such that a part of the suction passage 18 is partitioned by the nozzle plate 130. The nozzle plate 130 in the head main body 92 is expanded on both sides of the nozzle plate 13 of the head main body 91, and the expanded both side portions are provided with elastic members 131 that can be elastically deformed with respect to the lower surface of the exterior member 17. Are joined through. Thus, a through-hole penetrating in the plate thickness direction is formed on both sides of the nozzle plate 130, and the through-hole is formed when the nozzle plate 130 is joined to the exterior member 17. By communicating with the lower end of the suction passage 18 formed therein, a part of the suction passage 18 is partitioned.

  The elastic member 131 interposed between the nozzle plate 130 and the exterior member 17 is an annular shape having a hole in the center thereof, and the suction passage 18 formed in the nozzle plate 130 and the suction passage 18 formed in the exterior member 17. Communicate with each other. At the same time, the elastic member 131 is elastically deformed when the actuator 14 is driven, thereby allowing the displacement of the nozzle plate 130 and allowing the elastic partition member 15 to be expanded and contracted.

  The partition member 132 is joined to the lower surface (nozzle surface) of the nozzle plate 130 at both side positions. Each partition member 132 is formed with a concave groove 132a that opens upward and extends in the horizontal direction. The concave groove 132a communicates with the suction passage 18 and is located near the opening of the nozzle 12. Will be formed. In this configuration, since the suction port 18a is partitioned using the nozzle plate 130, there is an advantage that the accuracy of the relative position between the opening of the nozzle 12 and the suction port 18a is improved.

  FIG. 5 shows a modification of the configuration of the liquid suction system. In this modification, separate suction tanks 461 and 462 and suction pumps 471 and 472 are connected to the two suction ports 18a in the head main body 91, respectively. Accordingly, two suction tubes 451 and 452 and two air suction tubes 481 and 482 are provided. In this configuration, the suction force at each suction port 18a can be adjusted individually. For example, by adjusting the suction force at suction ports 18a and 18a to be equal to each other, the suction performance can be stabilized. obtain.

  FIG. 6 shows another modification of the configuration of the liquid suction system. In this example, the suction force variable (adjustment) means 5 capable of changing and adjusting the suction force at the suction port 18a is attached to one of the suction tubes 45 branched into two. Such a suction force varying means 5 is effective in adjusting the suction force so that the suction forces at the suction ports 18a are equal to each other. Specifically, any one of the configurations shown in FIGS.

  FIG. 7 shows an example in which the suction force varying means 5 is configured using a solenoid 51, and the plunger 52 that is returned and biased by energization of the solenoid 51 is placed on the side of the flexible suction tube 45. In addition to the arrangement, a pressing plate 53 that restricts the displacement of the suction tube 45 is disposed on the opposite side across the suction tube 45. When the plunger 52 is protruded rightward in FIG. 7 by the biasing force of the spring when not energized, the suction force varying means 5 having this structure is deformed by pushing the peripheral wall of the suction tube 45 inward. The area becomes smaller. This makes it possible to relatively reduce the suction force.

  FIG. 8 is an example in which the suction force varying means 5 is configured using a motor 54, and a screw 55 in which a screw 55 that rotates in the forward and reverse directions by driving the motor 54 is disposed on the side of the suction tube 45. 56 is screwed together. When the screw 55 is rotated by driving the motor 54, the suction force varying means 5 having this configuration is moved forward and backward with respect to the screwing plate 56. The peripheral wall of the suction tube 45 is pushed inward and deforms to reduce the cross-sectional area of the passage. This makes it possible to relatively reduce the suction force.

  FIG. 9 shows an example in which the suction force varying means 5 is configured using a solenoid 51. Unlike the configuration example shown in FIG. 7, the suction force varying means 5 is opened and closed by opening and closing a pressure relief port 45a formed on the peripheral wall of the suction tube 45. The suction power is changed. That is, when the closing plate 57 is attached to the tip of the plunger 52 and the plunger 52 is protruded to the right as shown by a two-dot chain line, the pressure release port 45a is blocked by the closing plate 57. Thus, while the suction force is relatively high, when the plunger 52 is returned to the left as shown by the solid line, the suction port 45a is opened, so that the suction force is relatively low.

  For example, even if foreign matter or the like is mixed into one suction passage 18 in the head body 91 and the suction force between the two suction ports 18a is different from each other, the pair of suction force variable means 5 is provided to provide a pair. It is possible to adjust and balance the suction force between the suction ports 18a. Therefore, the suction force varying means 5 can stabilize the suction performance in the head main body 91. The suction force varying means 5 may be attached to either one of the branched suction tubes 45, but may be attached to both of the branched suction tubes 45.

  FIG. 10 shows still another modified example of the configuration of the liquid suction system. In this example, a high-speed valve 61 (highly responsive) as a suction force variable means for the suction tube 45 (before branching) is shown. An open / close valve is provided. The high-speed valve 61 has a function of changing the suction force through each suction port 18a when the droplet is discharged (switching between execution and non-execution of suction).

  Here, the phenomenon at the time of discharging droplets will be described in detail. When the actuator 14 is driven, pressure is applied to the liquid material in the pressure chamber 11, and the liquid material is pushed out from the opening of the nozzle 12. Droplets grow larger and larger. Thus, when a droplet having a predetermined size is formed, the droplet (main droplet) is torn from the liquid material in the nozzle 12 and flies from the nozzle surface. In other words, after the start of the flight, in other words, when a predetermined time has elapsed from the start of driving of the actuator 14, satellite droplets and floating droplets are generated. Since the generation timing of satellite droplets and floating droplets is thus synchronized with the driving of the actuator 14, it is preferable to set the timing of suction so as to be synchronized with the driving of the actuator 14. Further, since the satellite droplets and the floating droplets are not generated from the start of driving of the actuator 14 until the main droplets fly, the fact that the suction is not performed can surely eliminate the influence on the flying of the main droplets. preferable. Therefore, in this example, the high-speed valve 61 is closed so as not to perform suction for a predetermined period corresponding to the period from the start of driving of the actuator 14 until the main droplets fly, and then the high-speed valve 61 is opened. Thus, suction is started at the generation timing of satellite droplets and floating droplets, and those unnecessary droplets are efficiently sucked. By using the high-speed valve 61 with high responsiveness, it is possible to change the suction force (switch between execution and non-execution of suction) within the period of the droplet discharge operation. In addition, by taking into account the response time of the high-speed valve and the time delay due to the flow path length, etc., by setting the on-off timing of the high-speed valve, the timing for discharging the liquid material and the timing for suctioning can be synchronized more accurately. Can be made. When the high-speed valve 61 can change the suction force by adjusting its opening, the opening of the high-speed valve 61 is set for a predetermined period corresponding to the period from the start of driving of the actuator 14 until the main droplets fly. The suction force may be increased by decreasing the suction force relatively, and then increasing the opening degree of the high-speed valve 61.

  FIG. 11 shows a configuration example suitable for changing the suction force between when a droplet is discharged and when it is not discharged in relation to the change in the suction force. In this example, a regulator 62 is interposed between the suction pump 47 and the suction tank 46, and by adjusting the pressure in the suction tank 46, the suction force through the suction port 18a is changed. ing. Specifically, when a droplet or a floating droplet is sucked when a droplet is discharged, the suction force is set to a relatively low value (for example, −0.01 to −10 kPa), while the droplet is not discharged. In order to suck the residual liquid droplets on the nozzle surface, the suction force is set to be relatively high (for example, −10 to −70 kPa). When suctioning residual droplets on the nozzle surface, a relatively high suction force is required. On the other hand, when sucking satellite droplets or floating droplets, a high suction force is not required. , There is a possibility that it may affect the flight of the main droplet, so by changing the suction force at the time of droplet discharge and non-discharge, The reliability of the head body 91 is further increased.

  Such a configuration for changing the suction force is not limited to the purpose of changing the suction force between when the droplet is discharged and when it is not discharged. For example, the suction force when the droplet is discharged depends on the operating environment of the head body 91. It can also be used when changing. That is, the liquid material having a relatively high viscosity, such as the liquid material discharged from the head main body 91 shown here, changes its viscosity according to the temperature, and accordingly, the generation amount of satellite droplets and floating droplets changes. become. Therefore, for example, if the suction force at the time of droplet discharge is changed according to the operating environment such as temperature, the suction force can be changed to the suction force according to the amount of satellite droplets or floating droplets generated. In addition, the suction performance is stabilized against environmental changes.

  Instead of providing the regulator 62, for example, by disposing the components related to the suction force varying means 5 shown in FIGS. It is possible to change the suction force between the non-ejection time and the non-ejection time. Further, even in the example provided with the high-speed valve 61 shown in FIG. 10 (however, the opening degree of the high-speed valve 61 can be adjusted), it is possible to change the suction force between when the droplet is discharged and when it is not discharged. Can do.

  12 to 14 show modified examples suitable for removing residual droplets adhering to the nozzle surface. In this example, a lead-out path 71 is formed on the nozzle surface of the nozzle plate 13 to guide residual droplets to the suction port 18a. The lead-out path 71 is constituted by a concave groove formed by being recessed from the nozzle surface, and the concave groove is formed to extend from the opening of the nozzle 12 to both sides toward the suction port 18a. .

  As described above, when the water repellent treatment is performed on the nozzle surface, when the liquid material is filled in the pressure chamber 11 or when bubbles in the pressure chamber 11 are removed, the nozzle 12 In some cases, the droplets adhering to the vicinity of the opening grow into a large spherical shape, and the droplets are difficult to move only with the suction force. On the other hand, when the outlet path 71 is formed on the nozzle surface, the droplet is prevented from becoming a large sphere, and as a result, the droplet can be easily removed by suction through the suction port 18a. Further, such a lead-out path 71 is also effective in preventing the residual droplet from crossing the opening of the nozzle 12 when the residual droplet is sucked.

  The cross-sectional shape of the groove is not limited to a rectangular cross section as shown in FIG. 14, but may be a V-groove shape having a triangular cross section, for example, or a semicircular cross section. Arbitrary shapes can be appropriately adopted as the cross-sectional shape of the groove.

  In the example illustrated in FIG. 15, the lead-out path 71 is configured by dividing a region where water repellent treatment is performed and a region where hydrophilic treatment is performed on the nozzle surface, instead of forming a concave groove on the nozzle surface. Specifically, a water-repellent treatment is performed in a band shape so as to extend from the opening of the nozzle 12 toward both sides (see reference numeral 72), while a water-repellent treatment is performed by applying a hydrophilic treatment to the other region 73. A boundary between the region and the hydrophilic treatment region is formed, thereby forming the lead-out path 71. Even in this configuration, the remaining droplets adhering to the nozzle surface are guided along the outlet path 71 to the suction port 18a, so that the remaining droplets are efficiently removed.

  The example shown in FIG. 16 is an example in which the region 72 subjected to the water repellent treatment and the region 73 subjected to the hydrophilic treatment are reversed with respect to the example shown in FIG. Also in this example, the outlet path 71 is constituted by the boundary between the water-repellent treatment area 72 and the hydrophilic treatment area 73, and residual droplets adhering to the nozzle surface are transferred to the suction port 18 a along the outlet path 71. The remaining droplets are efficiently removed. Since it is desirable that the periphery of the opening of the nozzle 12 has water repellency from the viewpoint of droplet discharge stability, in this example, the periphery of the opening of the nozzle 12 is subjected to water repellency treatment.

  FIG. 17 shows a configuration example in which the liquid material can be filled into the pressure chamber 11 by suction through the suction port 18a. In this example, a cap 81 that is in close contact with the lower end of the head main body 91 (liquid discharge head) and forms a sealed space 82 between the nozzle surface is provided. The cap 81 is attached to the head main body 91 in close contact with the lower end of the head main body 91 by disposing the cap 81 relative to the head main body 91 at, for example, a retracted position of the head main body 91. Alternatively, the cap 81 may be attached in close contact with the lower end of the head main body 91, for example, manually. By forming such a sealed space 82, if the suction tank 46 is brought to a negative pressure as the suction pump 47 is driven, the pressure chamber 11 also becomes a negative pressure state. It is possible to fill the pressure chamber 11 with the liquid material. In this configuration example, there is an advantage that it is not necessary to make the supply tank 42 in a positive pressure state by the supply pump 43.

  The cap 81 may be provided with an air release valve. When the pressure chamber 11 is filled with the liquid material and the liquid material comes out of the nozzle 12, the pressure chamber 11 is not filled with the liquid material more than necessary by opening the atmosphere release valve. The unnecessary liquid material around the 12 openings can be effectively sucked and removed.

  Further, the space between the exterior member 17 and the head main body 91 may be sealed with a cap. This sealing further improves the sealing performance and prevents the liquid material from coming into contact with the head body 91 such as the actuator 14, thereby preventing the actuator (piezoelectric body) 14 and the like from being deteriorated.

  In each of the above-described examples, the direction of the suction port 18a is set so as to perform suction in a direction orthogonal to the droplet discharge direction. For example, as shown in FIG. The suction port 18a may be opened downward at a height position corresponding to the height of the nozzle surface so as to perform suction in the direction opposite to the direction. For example, as shown in FIG. 19, the suction port 18a may be opened obliquely upward so as to perform suction in a direction inclined with respect to the droplet discharge direction.

  Further, here, the head main body 91 in which one nozzle 12 is formed on the nozzle plate 13 has been described as an example. However, the present technology can also be applied to a head main body in which a plurality of nozzles are formed on the nozzle plate. It is. The plurality of nozzles may be arranged side by side in a direction perpendicular to the paper surface shown in FIG. 2, for example, and in this case, the suction port corresponds to each one of the nozzles on both sides of the nozzle. A plurality of suction ports may be arranged side by side in the nozzle arrangement direction. Moreover, you may arrange | position the suction opening extended in a slit shape in the arrangement direction of a nozzle so that it may respond | correspond to a some nozzle or all the nozzles.

  Further, the configuration for discharging the liquid material in the head main body is not limited to the above-described configuration, and other configurations using a piezoelectric body may be adopted, and the piezoelectric body is not used. For example, a thermal method, a valve method, a plunger method, an electrostatic suction method, or the like may be employed.

  As described above, the present invention improves the reliability of the liquid discharge head by efficiently sucking unnecessary liquid at each time of discharging and non-discharging the liquid while reducing the size. For example, various patterns and uniform thin films can be formed in various technical fields such as the optoelectronics field and biomedical field, including the electronics field such as the manufacture of various devices such as flat panel displays and circuit boards. In addition to being useful as a liquid material ejection head and a liquid material ejection device, the present invention is useful as an ink ejection head and an image forming apparatus that form an image on a recording medium such as recording paper by ejecting ink.

It is a schematic perspective view which shows a liquid discharge apparatus. It is the longitudinal cross-sectional view and bottom view which show a head main body. It is the schematic which shows the structure of the liquid supply system with respect to a head main body, and a liquid suction system. It is a longitudinal cross-sectional view which shows the head main body which concerns on a modification. It is the schematic which shows the structure of the liquid supply system with respect to the head main body which concerns on a modification, and a liquid suction system. It is the schematic which shows the structure of the liquid suction system which concerns on the example which provided the suction force variable means. It is a schematic explanatory drawing which shows an example of a suction force variable means. It is a schematic explanatory drawing which shows another example of a suction force variable means. It is a schematic explanatory drawing which shows another example of a suction force variable means. It is the schematic which shows the structure of the liquid suction system which concerns on the example which provided the high speed valve as a suction force variable means. It is the schematic which shows the structure of the liquid suction system which concerns on the example which provided the regulator as a suction force variable means. It is a longitudinal cross-sectional view which shows the head main body which concerns on a modification. It is a bottom view of a head body. FIG. 14 is an end view of XIV-XIV in FIG. 13. It is a bottom view of the head body concerning a modification. It is a bottom view of a head body concerning another modification. It is a longitudinal cross-sectional view which shows the head main body which concerns on the example which provided the cap. It is a longitudinal cross-sectional view which shows the head main body which concerns on the modification regarding arrangement | positioning of a suction opening. It is a longitudinal cross-sectional view which shows the head main body which concerns on another modification regarding arrangement | positioning of a suction opening.

11 Pressure chamber 12 Nozzle 13 Nozzle plate 130 Nozzle plate 14 Actuator (pressure applying means)
18 Suction passage 18a Suction port 46 Suction tank 47 Suction pump 5 Suction force variable means 51 Solenoid (Suction force variable means)
54 Motor (Suction force variable means)
61 High-speed valve (Various suction force means)
62 Regulator (Various suction force means)
7 Liquid discharge head 71 Derivation path 81 Cap (sealing member)
91 Head Body 92 Head Body A Liquid Discharge Device

Claims (8)

A pressure chamber for storing a liquid, a nozzle plate having a nozzle surface opened at a tip of a nozzle communicating with the pressure chamber, and applying the pressure to the liquid in the pressure chamber, thereby allowing the liquid in the pressure chamber to pass through the nozzle. A head body including pressure applying means for discharging
A suction means that has a suction port located in the vicinity of the nozzle opening, and sucks unnecessary liquid present around the nozzle opening through the suction port when the liquid is discharged and when the liquid is not discharged, respectively. A liquid ejection head comprising: The liquid discharge head according to claim 1,
A plurality of the suction ports are liquid ejection heads arranged so as to be symmetric with respect to the central axis of the nozzle. The liquid discharge head according to claim 1 or 2,
In the suction unit, the suction passage including the suction port is formed in the head main body. The liquid ejection head according to claim 3,
The suction port is a liquid ejection head that is defined by a nozzle surface of the nozzle plate. The liquid discharge head according to any one of claims 1 to 4,
A liquid ejection head further comprising suction force variable means for changing the suction force of the suction means. The liquid discharge head according to any one of claims 1 to 5,
A liquid discharge head, wherein a discharge path that leads from the nozzle opening toward the suction port and guides the unnecessary liquid to the suction port is formed on a nozzle surface of the nozzle plate. The liquid discharge head according to any one of claims 1 to 6,
A sealing member that forms a sealed space in which the opening of the nozzle communicates by being attached to the head body;
The suction port of the suction means is a liquid ejection head that opens into the sealed space.   A liquid ejection apparatus comprising the liquid ejection head according to claim 1.

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