JP2011178089A - Liquid jet head, liquid jet head unit, and liquid jetting apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a liquid jet head, a liquid jet head unit and a liquid jetting apparatus restraining small liquid droplets from reaching a jetted medium and restraining a liquid jetting failure caused by the small liquid droplets to improve printing quality. <P>SOLUTION: The liquid jet head includes: a head body 10 having nozzle openings 11 for jetting liquid; a cover 20 provided projecting in the jet direction of the liquid around a liquid jetting surface 12 to which the nozzle openings 11 are opened; a flow straightening vane 30 provided in a position away from the liquid jetting surface 12 in the cover 20 and provided with openings 31 in regions facing the nozzle openings 11; and a voltage applying means 40 applying voltage to the flow straightening vane 30. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a liquid ejecting head that ejects liquid from a nozzle opening, a liquid ejecting head unit, and a liquid ejecting apparatus.

  A liquid ejecting apparatus typified by an ink jet recording apparatus such as an ink jet recording head or a plotter is a liquid ejecting capable of ejecting a liquid such as ink stored in a liquid storing means such as a cartridge or a tank as a droplet (ink droplet). A head (hereinafter also referred to as a recording head).

  The liquid ejecting apparatus includes a serial type liquid ejecting apparatus that performs printing while moving the liquid ejecting head in the scanning direction with respect to an ejected medium such as a recording sheet such as paper, and a nozzle across the width of the recording medium. A line-type liquid ejecting apparatus that performs printing simply by fixing a liquid ejecting head provided with an opening and transporting a recording medium has been put into practical use (for example, see Patent Document 1).

  However, in any of the serial type and line type liquid ejecting apparatuses, since the ejection target medium and the liquid ejecting head are relatively moved, an air flow is generated by this relative movement, and ink is ejected from the nozzle openings. When this occurs, small droplets (called mist or satellite droplets) separated from the main droplets (main droplets) are generated, and the small droplets are separated from the main droplets of the ejected medium by the flow of airflow. The print quality deteriorates due to adhesion to the ink. Further, the small droplets adhere to the liquid meniscus at the nozzle opening and destroy the meniscus, and the droplet cannot be normally discharged from the nozzle opening.

  In order to solve such a problem, a hood that covers from the nozzle opening to the vicinity of the ejected medium is provided on the liquid ejecting surface side of the recording head that ejects ink, and the relative movement between the ejected medium and the recording head is provided. A drawing head device has been proposed in which small droplets are prevented from landing at positions different from the main droplets by the generated airflow (see, for example, Patent Document 2).

Japanese Patent Laid-Open No. 5-16370 Japanese Patent Laid-Open No. 2000-62166

  However, as in Patent Document 2, when a hood is provided only on the recording head, turbulent air flow is generated by the hood, and small droplets land on a position different from the main droplet of the ejection target medium, and printing is performed. There is a problem that the quality deteriorates and the meniscus is destroyed.

  Such a problem becomes prominent particularly when high-speed printing is performed by increasing the relative moving speed of the recording head and the ejection target medium.

  Such a problem exists not only in an ink jet recording head that ejects ink, but also in a liquid ejecting head that ejects liquid other than ink.

  In view of such circumstances, the present invention suppresses the landing of small droplets on an ejection target medium, suppresses liquid ejection defects due to small droplets, and improves the print quality. An object is to provide an ejection head unit and a liquid ejection apparatus.

  An aspect of the present invention that solves the above-described problems includes a head body having a nozzle opening for ejecting liquid, a cover that protrudes in the liquid ejecting direction around a liquid ejecting surface on which the nozzle opening opens, A rectifying plate provided in the cover at a position away from the liquid ejection surface and having an opening in a region opposite to the nozzle opening; and a voltage applying means for applying a voltage to the rectifying plate. The liquid ejecting head is characterized in that.

  In this mode, when a droplet is ejected from the nozzle opening while a voltage is applied to the rectifying plate, the main droplet of the ejected droplet moves in a direction crossing the ejection direction due to the influence of the electric charge charged on the rectifying plate. The small droplets separated from the main droplets are moved by being pulled by the electric charge charged on the current plate, and landed on the current plate to form a mist. Droplets or small droplets can be prevented from landing on the ejection target medium or adhering to the meniscus of the nozzle opening. In addition, by providing the cover, airflow due to relative movement between the ejection target medium and the liquid ejecting head, external airflow, and the like are shielded by the cover, and an airflow different from the airflow generated by the airflow generating means is generated in the vicinity of the liquid ejecting surface. Generation | occurrence | production can be suppressed and the landing position shift of a main droplet can be suppressed.

  Here, it is preferable that the rectifying plate is provided in a plurality of layers at different positions from the liquid ejection surface, and the voltage applying unit applies a voltage to each rectifying plate. According to this, a small droplet can be more reliably trapped by the current plate by charging the current plate with a plurality of layers.

  Moreover, it is preferable that the said baffle plate is a mesh shape whose opening is a square. According to this, the cost of the current plate can be reduced, and the efficiency of trapping small droplets on the current plate can be increased.

  It is preferable that a plurality of the head main bodies are provided, and the cover is provided continuously around the plurality of head main bodies. According to this, the number of parts can be reduced and the cost can be reduced.

  In addition, it is preferable that an airflow generation unit that generates an airflow along the surface direction of the liquid ejection surface is provided between the current plate and the liquid ejection surface. According to this, it is possible to more reliably perform trapping by the rectifying plate by moving the small droplets in the direction perpendicular to the ejection direction by the airflow.

  Moreover, it is preferable that the said airflow generation means generate | occur | produces the airflow of the gas which got moisture. According to this, it is possible to suppress the drying of the liquid in the vicinity of the nozzle opening from being promoted by the air flow generated by the air flow generating means, and to reduce ejection failures due to the drying / curing of the liquid.

According to another aspect of the invention, there is provided a liquid ejecting head unit including two or more liquid ejecting heads according to the above aspect.
In such an embodiment, a head unit having multiple nozzles can be easily formed.

According to another aspect of the invention, there is provided a liquid ejecting apparatus including the liquid ejecting head or the liquid ejecting head unit according to the above aspect.
In this aspect, it is possible to realize a liquid ejecting apparatus that can improve printing quality and perform high-speed printing.

3 is a perspective view of a recording head according to Embodiment 1. FIG. 2A and 2B are a bottom view and a main part sectional view of the recording head according to the first embodiment. FIG. 4 is a cross-sectional view of a main part illustrating the operation of the recording head according to the first embodiment. FIG. 3 is a bottom view of the head unit according to the first embodiment. 1 is a schematic perspective view of a recording apparatus according to Embodiment 1. FIG. 6 is a perspective view of a recording head according to Embodiment 2. FIG. FIG. 6 is a cross-sectional view of a main part of a recording head according to a second embodiment. FIG. 6 is a cross-sectional view of a main part of a recording head according to a third embodiment. FIG. 6 is a bottom view of a head unit according to a fourth embodiment.

Hereinafter, the present invention will be described in detail based on embodiments.
(Embodiment 1)
FIG. 1 is a perspective view illustrating an ink jet recording head which is an example of a liquid ejecting head according to Embodiment 1 of the present invention, and FIG. 2 is a bottom view and a main part sectional view of the ink jet recording head.

  As shown in FIG. 1, an ink jet recording head 1 (hereinafter also referred to as a recording head 1) that is an example of a liquid ejecting head of the present embodiment includes a head body 10 and a cover that covers a liquid ejecting surface 12 of the head body 10. 20, a rectifying plate 30 fixed to the cover 20, and a voltage applying means 40.

  The head main body 10 is provided with a plurality of nozzle openings 11 that discharge ink as a liquid and open on one surface. The surface on which the nozzle opening 11 is opened is a liquid ejection surface 12 that ejects ink as a liquid.

  Further, the head body 10 is provided with a flow path 13 communicating with the nozzle opening 11 inside, and an ink droplet is generated from the nozzle opening 11 by causing a pressure change to the ink in the flow path 13 by pressure generation means (not shown). Is discharged. In addition, as a pressure generating means for generating a pressure change in the flow path 13, for example, a piezoelectric actuator using a piezoelectric element having a piezoelectric material exhibiting an electromechanical conversion function, or a heating element is disposed in the flow path 13. In the flow path 13, the ink droplets are ejected from the nozzle openings 11 by bubbles generated by the heat generated by the heating elements, or static electricity is generated between the diaphragm and the electrode, and the diaphragm is deformed by electrostatic force. A so-called electrostatic actuator that causes a change in pressure to eject ink droplets from the nozzle openings 11 can be used.

  A cover 20 is provided on the side surface of the head body 10 on the liquid ejection surface 12 side. The cover 20 surrounds the liquid ejecting surface 12 of the recording head 1 and is provided so as to protrude in the ink ejection direction. The cover 20 of the present embodiment is formed of a rectangular tube-shaped member whose opening is rectangular, and is integrated with the head body 10 by inserting and fixing the liquid ejection surface 12 side of the head body 10 into one opening. Has been. Such a cover 20 covers the flying area where ink is ejected opposite to the liquid ejecting surface 12 from the liquid ejecting surface 12 to the vicinity of the recording medium. Suppress.

  A rectifying plate 30 is fixed inside the cover 20. The rectifying plate 30 is composed of a plate-like member provided opposite to the liquid ejecting surface 12 and at a position away from the liquid ejecting surface 12. As will be described later, since a voltage is applied to the rectifying plate 30, it is preferable that at least the mounting portions of both are electrically insulated. If necessary, a voltage may be applied to the cover 20 together with the rectifying plate 30 using the cover 20 as a conductive member.

  The rectifying plate 30 is provided with an opening 31 having a size that allows ink droplets (main droplets) ejected from the nozzle openings 11 to pass through a region facing each nozzle opening 11. Here, the opening 31 through which the main droplet can pass opposite to the nozzle opening 11 may be, for example, the opening 31 provided independently for each nozzle opening 11, or two or more nozzles The opening 31 provided corresponding to the nozzle opening group which consists of the opening 11 may be sufficient. That is, one opening 31 may be provided for each nozzle opening 11, or one opening 31 may be provided in common for the plurality of nozzle openings 11.

  Further, the rectifying plate 30 may be entirely closed except for the area other than the opening 31, and other openings may be provided in addition to the area facing the nozzle opening 11. As the rectifying plate 30 provided with other openings other than the region facing the nozzle opening 11, for example, the openings 31 are masked by making a conductive material such as metal, conductive resin, conductive fiber or the like into a lattice shape. The mesh member provided in the shape of a mesh is mentioned. If the pitch (interval) of the openings 31 of the mesh member is an integral multiple of the pitch of the nozzle openings 11, the openings 31 can be opposed to all the nozzle openings 11. In addition, the size and pitch of the openings 31 of the mesh member may be provided so that one opening 31 faces each nozzle opening 11 as described above, and one opening 31 includes a plurality of openings 31. It may be provided so as to face the nozzle opening 11.

  The material of the rectifying plate 30 is not particularly limited as long as it has conductivity and can apply a voltage, and the surface may be coated with an insulating material. In addition, an adsorption layer made of a material having adsorptivity, that is, water absorption, for example, may be provided on the surface of the rectifying plate 30. According to this, when ink adheres to the rectifying plate 30, the ink is adsorbed. It is possible to suppress the ink adhering to and held by the rectifying plate 30 having a certain amount of ink from falling and adhering to the ejected medium at an unexpected timing.

  Such a rectifying plate 30 is arranged at a position away from the liquid ejection surface 12 by a predetermined distance as described above. Thereby, a space 32 for moving small droplets is defined between the current plate 30 and the liquid ejection surface 12.

  The rectifying plate 30 is preferably provided in the vicinity of the liquid ejecting surface 12 between the liquid ejecting surface 12 and the recording medium. This is because the main droplet ejected from the nozzle opening 11 may be landed at a position deviated from the nozzle opening 11 due to being largely affected by the deviation of the ejection direction and the air flow as it leaves the nozzle opening 11. This is because if the rectifying plate 30 is separated from the liquid ejection surface 12, the error increases and the main droplet may not pass through the opening 31 of the rectifying plate 30. Therefore, by providing the rectifying plate 30 in the vicinity of the liquid ejection surface 12, the main droplet discharged from the nozzle opening 11 can easily pass through the opening 31. In the present embodiment, the interval between the liquid ejection surface 12 and the rectifying plate 30 is set to about 1 mm.

  Further, the space 32 between the current plate 30 and the liquid ejection surface 12 is externally provided by a pair of communication holes 21 provided so as to face each other on the side surfaces of the cover 20 on both sides in the direction in which the nozzle openings 11 are arranged in parallel. Communicate.

  The voltage applying unit 40 applies a predetermined voltage to the rectifying plate 30, and may be any unit that applies a positive or negative voltage with reference to the head body 10 or the ground, for example. Whether to apply positive or negative may be determined by the electric charge charged in the ejected ink droplet, and a high voltage is applied so that the rectifying plate 30 is charged oppositely to the electric charge of the ink droplet. In this embodiment, since the ink droplet is negatively charged, a positive DC high voltage is applied to the rectifying plate 30.

  The voltage applied to the rectifying plate 30 by the voltage applying means 40 is such a voltage that a small droplet separated from the main droplet is drawn under the influence of charging on the rectifying plate 30. By the way, the size (mass) of the main droplets and the size (mass) of the small droplets change due to the influence of the performance of the pressure generating means and the drive waveform that defines the weight and speed of the ejected ink droplets. Depending on these, it may be determined appropriately.

  The ejection of ink droplets from the recording head 1 will be described with reference to FIG. FIG. 3 is a cross-sectional view of the main part showing the ink droplet ejection state of the ink jet recording head.

  As shown in FIG. 3A, in the state where a positive high voltage is applied to the rectifying plate 30 by the voltage applying means 40, a pressure change is generated in the flow path 13 by a pressure generating means (not shown) to eject ink droplets. To start. As a result, the meniscus rises in a columnar shape from the nozzle opening 11, and an ink droplet A is ejected from the nozzle opening 11 by cutting off a part of the columnar shape as shown in FIG. At this time, the ink droplet A flies so as to extend the tail portion, and as shown in FIG. 3C, a part of the tail portion of the ink droplet A is torn off, so that the main droplet B (main droplet) and the small droplet portion are small. Separated into droplet C (satellite droplet). Further, the small droplet C is also generated when the ink droplet A is separated by separating a part of the columnar shape in FIG.

  As shown in FIG. 3 (d), the main droplet B ejected in this way has a mass larger than that of the small droplet C. Passes through the opening 31 of the current plate 30. On the other hand, since the small droplet C has a smaller mass than the main droplet B, the opening 31 of the rectifying plate 30 is provided by the attractive force due to the charging of the rectifying plate 30 as shown in FIG. It is moved to the area that is not, and landed on the current plate 30. As a result, the small droplet C does not land on the ejection target medium, and the flying small droplet C is prevented from floating by turbulence and adhering to the meniscus of the nozzle opening 11 to destroy the meniscus. Can do. Accordingly, it is possible to suppress the deterioration of the print quality due to the influence of the small droplet C and improve the print quality.

  In addition, since the landing of the small droplet C on the ejection medium can be suppressed, the flying speed of the ink droplet A (main droplet B) can be increased. Incidentally, when the flying speed of the ink droplet A is increased, the tail becomes longer and many small droplets C are separated. In this embodiment, even if many small droplets C are generated, the small droplets C are generated. Since landing on the current plate 30 and landing on the ejection target medium can be suppressed, the flying speed of the ink droplet A (main droplet B) can be increased.

  Furthermore, since the landing of the small droplet C on the ejection medium can be suppressed, the relative movement speed between the ejection medium and the recording head 1 can be increased, and high-speed printing can be realized. Incidentally, when the relative moving speed of the ejection target medium and the recording head 1 is increased, turbulence is generated, and the generation of small droplets C and a lot of landing position deviation occur. However, in this embodiment, the small droplets C Is landed on the current plate 30, high-speed printing can be realized.

  Here, the entire rectifying plate 30 does not need to be formed of a conductive material. For example, when a lattice-shaped mesh member is used, a member extending in one direction is a conductive material, and a member extending in the other direction is used. An insulating material may be used, and a voltage may be applied to the conductive material portion. Further, members extending in one direction may be alternately formed of a conductive material and an insulating material, and members extending in the other direction may be alternately formed of a conductive material and an insulating material. In this case, since the charged state around the nozzle opening 11 through which the droplet passes is not uniform, even if the minute droplet passes through the center of the nozzle opening 11, it is reliably pulled in the charged direction. It is possible to trap small droplets more reliably.

  A plurality of such recording heads 1 are integrally fixed to constitute a head unit. Here, the head unit of this embodiment will be described with reference to FIG.

  The head unit 100 includes a plurality of recording heads 1 and a base plate 110 to which the plurality of recording heads 1 are fixed.

  The base plate 110 is made of a plate-like member such as stainless steel and has a holding hole 111 into which the liquid ejection surface 12 side of each recording head 1 is inserted. The holding hole 111 has an opening area slightly larger than the outer periphery of the recording head 1 on the liquid ejecting surface 12 side, and the opposite side of the recording head 1 from the liquid ejecting surface 12 is inserted into the holding hole 111 of the base plate 110 for recording. A flange portion 14 provided on the outer periphery of the head 1 is fixed to one surface of the base plate 110 via screws or the like.

  In the present embodiment, the plurality of recording heads 1 are arranged in parallel in the first direction Y, which is the direction in which the nozzle openings 11 are arranged. In addition, the column composed of a plurality of recording heads 1 arranged in parallel in the first direction Y has a direction (second direction) intersecting the direction in which the nozzle openings 11 are arranged in parallel (first direction Y). Two rows are arranged side by side in X). The two rows of the recording heads 1 arranged in parallel in the second direction X are arranged at positions slightly shifted from each other in the second direction X. That is, the two rows of the recording heads 1 constitute a head group so that the recording heads 1 are arranged in a staggered manner. In one head group, adjacent recording heads 1 have nozzle openings 11 at the end of the nozzle row of one recording head 1 and nozzle openings 11 at the end of the nozzle row of the other recording head 1. The nozzle openings 11 are provided in the same position in the direction in which the nozzle openings 11 are arranged (the first direction Y). Thus, printing can be performed in all regions by the two rows of recording heads 1 in the width direction intersecting the transport direction of the ejection target medium. In this embodiment, the head unit 100 is provided with two head groups composed of four ink jet recording heads 1.

  Such a head unit 100 is mounted on the ink jet recording apparatus 200. Here, the ink jet recording apparatus will be described with reference to FIG.

  An ink jet recording apparatus 200 that is an example of a liquid ejecting apparatus according to the present embodiment performs printing by fixing a head unit 100 (recording head 1) and transporting a recording sheet S such as paper that is an ejected medium. This is a so-called line type recording apparatus. Specifically, the ink jet recording apparatus 200 includes an apparatus main body 201, a head unit 100 that includes a plurality of recording heads 1 and is fixed to the apparatus main body 201, a conveyance unit 202 that conveys the recording sheet S, and a head. The platen 203 which supports the back surface side opposite to the printing surface of the recording sheet S which the unit 100 opposes is provided.

  The head unit 100 is fixed to the apparatus main body 201 so that the juxtaposed direction (first direction Y) of the nozzle openings 11 of the recording head 1 is a direction that intersects the conveyance direction of the recording sheet S.

  The transport unit 202 includes a first transport unit 204 and a second transport unit 205 provided on both sides of the head unit 100 in the transport direction of the recording sheet S.

  The first conveying unit 204 includes a driving roller 204a, a driven roller 204b, and a conveying belt 204c wound around the driving roller 204a and the driven roller 204b. Similarly to the first transport unit 204, the second transport unit 205 includes a driving roller 205a, a driven roller 205b, and a transport belt 205c.

  Driving means such as a driving motor (not shown) is connected to the driving rollers 204a and 205a of the first conveying means 204 and the second conveying means 205, and the conveying belt 204c, The recording sheet S is conveyed on the upstream side and the downstream side of the head unit 100 as the 205c is driven to rotate.

  In the present exemplary embodiment, the first conveying unit 204 and the second conveying unit 205 including the driving rollers 204a and 205a, the driven rollers 204b and 205b, and the conveying belts 204c and 205c are exemplified. You may further provide the holding means hold | maintained on the conveyance belts 204c and 205c. As the holding unit, for example, a charging unit that charges the outer peripheral surface of the recording sheet S may be provided, and the recording sheet S charged by the charging unit may be attracted onto the conveying belts 204c and 205c by the action of dielectric polarization. . Further, as a holding unit, a pressing roller may be provided on the conveying belts 204c and 205c, and the recording sheet S may be sandwiched between the pressing roller and the conveying belts 204c and 205c.

  The platen 203 is made of a metal or resin having a rectangular cross section provided between the first transport unit 204 and the second transport unit 205 so as to face the head unit 100. The platen 203 supports the recording sheet S conveyed by the first conveying unit 204 and the second conveying unit 205 at a position facing the head unit 100.

  The platen 203 may be provided with a suction unit that sucks the conveyed recording sheet S on the platen 203. Examples of the suction means include a device that sucks and sucks the recording sheet S and a device that electrostatically sucks the recording sheet S by electrostatic force.

  Further, although not shown, each storage head 1 of the head unit 100 is connected to an ink storage means such as an ink tank or an ink cartridge in which ink is stored so as to be able to supply ink. For example, the ink storage unit may be held on the head unit 100 or may be held at a position different from the head unit 100 in the apparatus main body 201.

  In such an ink jet recording apparatus 200, the recording sheet S is transported by the transport unit 204, and printing is performed on the recording sheet S supported on the platen 203 by the head unit 100. The printed recording sheet S is conveyed by the conveying unit 202.

  In such printing by the ink jet recording apparatus 200, the recording head 1 is provided with the covers 20 that cover the liquid ejection surface 12 on both sides in the conveyance direction of the recording sheet S. Occurrence in the vicinity of the liquid ejection surface 12 can be suppressed. In particular, the recording head 1 of the present embodiment is mounted on the ink jet recording apparatus 200 so that the covers 20 are arranged on both sides in the transport direction, and thus covers the wind (airflow) generated when the recording sheet S is transported. 20 can be effectively suppressed.

  Further, since the rectifying plate 30 is provided so as to shield the conveyance region of the recording sheet S and the liquid ejecting surface 12, the air flow from the recording sheet S side is also shielded by the rectifying plate 30, and the liquid ejecting surface. The generation of air current in the vicinity of 12 can be suppressed.

  In this way, the influence of the airflow due to the conveyance of the recording sheet S is suppressed in the space 32 between the liquid ejection surface 12 and the rectifying plate 30, and the landing of the small droplet C is achieved only by applying a voltage to the rectifying plate 30. Since the position can be controlled, the small droplet C can be landed by the rectifying plate 30.

  In the present embodiment, the head unit 100 having a plurality of recording heads 1 is mounted on the ink jet recording apparatus 200. However, the present invention is not limited to this, and one or a plurality of recording heads 1 are directly connected to the ink jet recording apparatus. You may mount in the apparatus 200. FIG. A plurality of head units 100 may be mounted on the ink jet recording apparatus 200.

(Embodiment 2)
6 and 7 are a perspective view and a cross-sectional view of an ink jet recording head which is an example of a liquid jet head according to Embodiment 2 of the present invention. In addition, the same code | symbol is attached | subjected to the member similar to Embodiment 1 mentioned above, and the overlapping description is abbreviate | omitted.

  In the liquid ejecting head 1A of the present embodiment, the rectifying plate 50 is provided on the side opposite to the liquid ejecting surface 12 of the cover 20, and the same voltage as that of the rectifying plate 30 is applied to the rectifying plate 50 from the voltage applying unit 40A. It is to be applied.

  In the present embodiment, the rectifying plate 50 is made of a plate-like member having the same area as the rectifying plate 30, and an opening 51 that opens opposite to the opening 31 of the rectifying plate 30 is provided.

  As such a rectification | straightening board 50, what has the same material and the same structure as the rectification | straightening board 30 mentioned above can be used, for example. In the present embodiment, the same mesh member as that of the current plate 30 is used as the current plate 50. That is, the current plate 50 is provided with openings 51 having the same size and the same pitch as the openings 31 of the current plate 30.

  In this way, by providing the rectifying plate 50 on the side of the cover 20 opposite to the liquid ejection surface 12 of the rectifying plate 30, small droplets that could not be trapped by the rectifying plate 30 are attracted by the electric charge charged on the rectifying plate 50. Trapped and the print quality can be further improved. Further, even if a mist-like droplet floats in the space between the rectifying plate 30 and the rectifying plate 50, the rectifying plate 30 and 50 can reliably prevent the mist-like droplet from escaping outside. Can be trapped.

  Further, the flow of air into the cover 20 can be prevented from entering by the rectifying plate 50. Thereby, the influence of the external airflow on the flying of the ink in the cover 20 can be reduced, the deviation of the landing position of the ink droplets on the ejection target medium can be suppressed, and the printing quality can be improved.

  The cover 20 is preferably provided with a length as close as possible to the ejected medium when the recording head 1 is mounted on the ink jet recording apparatus, and the rectifying plate 50 has an external air flow in the cover 20. In order to function in order to suppress intrusion, it is preferable to provide the cover 20 on the most ejected medium side, that is, on the opening side of the cover 20.

(Embodiment 3)
FIG. 8 is a cross-sectional view of an ink jet recording head which is an example of a liquid jet head according to Embodiment 3 of the present invention. In addition, the same code | symbol is attached | subjected to the member similar to Embodiment 2 mentioned above, and the overlapping description is abbreviate | omitted.

In the liquid jet head 1 </ b> B of the present embodiment, the airflow generation means 60 is provided.
The air flow generation means 60 generates an air flow in the space 32 between the liquid ejection surface 12 and the rectifying plate 30 along the surface direction of the liquid ejection surface 12. In the present embodiment, the airflow generation means 60 composed of a blower is provided at a location where one communication hole 21 on the outer periphery of the cover 20 opens.

  Thus, gas is blown from the airflow generation means 60 into the cover 20 through the one communication hole 21, and the nozzle openings 11 are arranged in parallel in the space 32 between the liquid ejection surface 12 and the rectifying plate 30. An air flow is generated along the surface direction of the liquid ejection surface 12 and the cover 20 in the direction. The airflow blown from the airflow generation means 60 is discharged from the other communication hole 21 to the outside of the cover 20, thereby suppressing the generation of turbulent airflow when the airflow contacts the cover 20.

  In addition, the airflow generation means 60 is not limited to a blower, For example, a suction pump etc. may be sufficient.

  As will be described in detail later, the airflow generated by the airflow generation means 60 is a small droplet that is separated from the main droplet by the main droplet of the ink droplet ejected from the nozzle opening 11 going straight without being influenced by the airflow. Is the flow velocity that moves under the influence of airflow. By the way, the size (mass) of the main droplets and the size (mass) of the small droplets change due to the influence of the performance of the pressure generating means and the drive waveform that defines the weight and speed of the ejected ink droplets. Depending on these, it may be determined appropriately.

  By providing such an airflow generation means 60, an airflow can be generated in the space 32 between the liquid ejecting surface 12 and the rectifying plate 30 along the surface direction of the liquid ejecting surface 12, thereby reducing a small amount. The liquid droplets and the mist-shaped liquid droplets are caused to flow by the air current, and coupled with the influence of charging by the voltage application by the voltage application means 40, so that they are reliably trapped by the region where the opening 31 of the rectifying plate 30 is not provided. Become. Since the main droplet B as shown in FIG. 3D has a larger mass than the small droplet C, the main droplet B passes through the opening 31 of the mesh-like rectifying plate 30 without being flowed by the airflow.

(Embodiment 4)
FIG. 9 is a bottom view of a head unit according to Embodiment 4 of the invention. In addition, the same code | symbol is attached | subjected to the member similar to Embodiment 2 mentioned above, and the overlapping description is abbreviate | omitted.

  As shown in FIG. 9, the head unit 100 </ b> A of this embodiment includes a plurality of recording heads 1 </ b> C and a base plate 110.

  The head body 10 is fixed to each of the holding holes 111 of the base plate 110. In the present embodiment, two head groups 2 having the head main bodies 10 (two rows of head main bodies 10) arranged in a staggered manner are provided, as in the first embodiment. This head group 2 is one recording head 1C in this embodiment.

  Further, each head group 2 composed of two rows of head bodies 10 arranged in parallel in the second direction X is covered with a common cover 20B.

  The cover 20 </ b> B is provided for each recording head 1 </ b> C, and a pair of covers 20 </ b> B provided continuously in the direction in which the plurality of head bodies 10 are arranged in the same direction (the same direction as the direction in which the nozzle openings 11 are arranged in parallel). It consists of a plate-shaped member. In the present embodiment, the cover 20B is provided on both sides in the second direction X of each recording head 1C (head group 2).

  Each recording head 1C (head group 2) of the head unit 100A is provided with one rectifying plate 30A and a rectifying plate 50A that are common to the head main bodies 10.

  The rectifying plates 30A and 50A are provided opposite to the liquid ejection surfaces 12 of the plurality of head main bodies 10, and the openings 31 and 51 of the rectifying plates 30A and 50A are the same as in the second embodiment described above. It is provided at a position opposite to the nozzle openings 11 of all the head main bodies 10.

  Furthermore, each recording head 1C (head group 2) is provided with a voltage applying means 40B so that a voltage can be applied to the rectifying plates 30A and 50A.

  In such a configuration, unlike the first embodiment described above, it is not necessary to provide the cover 20, the rectifying plate 30 and the voltage applying means 40 for each head body 10, and the number of parts can be reduced to reduce the cost. .

  In this embodiment, the cover 20B, the rectifying plates 30A and 50A, and the voltage applying unit 40B are provided for each recording head 1C (head group 2). However, the present invention is not limited to this, and a plurality of head groups 2 are provided. You may make it provide a common cover, a baffle plate, and a voltage application means. In this case, the head unit 100A itself can be a recording head.

(Other embodiments)
As mentioned above, although each embodiment of this invention was described, the basic composition of this invention is not limited to what was mentioned above.

  In the above-described embodiment, the mesh-like material is used as the rectifying plates 30, 30A, 50, and 50A. However, as described above, the materials and shapes of the rectifying plates 30, 30A, 50, and 50A are particularly limited thereto. It is not limited.

  In Embodiment 3 described above, the airflow generation means 60 is provided in the recording head 1B. However, the present invention is not particularly limited thereto. For example, one airflow generation means may be provided for each head unit 100. The ink jet recording apparatus 200 may be provided with airflow generation means.

  In addition, as the airflow generation means 60 of each of the above-described embodiments, for example, a humid gas flow may be generated. In order to generate such a humid airflow, a humidifier or the like may be provided. In this way, the airflow generation means generates a humid airflow, thereby suppressing the drying of the liquid near the nozzle opening from being accelerated by the airflow generated by the airflow generation means, and drying and curing the liquid. It is possible to reduce the ejection failure due to.

  In the first and second embodiments described above, as the ink jet recording apparatus 200, the recording head 1, 1A (head unit 100) is fixed, and printing is performed simply by transporting the recording sheet S. Although the recording apparatus 200 has been illustrated, the present invention is not particularly limited thereto. For example, a serial type ink jet type that performs printing while moving the recording heads 1 and 1A (head unit 100) in the main scanning direction with respect to the ejection target medium. The present invention can also be applied to a recording apparatus.

  In the above embodiment, an ink jet recording head has been described as an example of a liquid ejecting head, and an ink jet recording apparatus has been described as an example of a liquid ejecting apparatus. The present invention is intended for the entire apparatus, and can of course be applied to a liquid ejecting head and a liquid ejecting apparatus that eject liquid other than ink. Other liquid ejecting heads include, for example, various recording heads used in image recording apparatuses such as printers, color material ejecting heads used in the manufacture of color filters such as liquid crystal displays, organic EL displays, and FEDs (field emission displays). Examples thereof include an electrode material ejection head used for electrode formation, a bio-organic matter ejection head used for biochip production, and the like, and can also be applied to a liquid ejection apparatus provided with such a liquid ejection head.

  A ink droplet, B main droplet, C small droplet, 1, 1A, 1B, 1C inkjet recording head (liquid ejecting head), 2 head group, 10 head main body, 11 nozzle opening, 12 liquid ejecting surface, 20, 20A , 20B cover, 30, 30A, 50, 50A rectifying plate, 31, 51 opening, 40 voltage applying means, 60 air flow generating means, 100, 100A head unit, 110 base plate, 200 inkjet recording apparatus (liquid ejecting apparatus)

Claims (9)

A head body having a nozzle opening for ejecting liquid;
A cover provided around the liquid ejecting surface where the nozzle opening is opened and protruding in the liquid ejecting direction;
A rectifying plate provided in a position away from the liquid ejection surface in the cover and having an opening in a region opposite to the nozzle opening;
And a voltage applying unit that applies a voltage to the rectifying plate.   The liquid ejecting head according to claim 1, wherein the rectifying plate is provided in a plurality of layers at different positions from the liquid ejecting surface, and the voltage applying unit applies a voltage to each rectifying plate.   The liquid jet head according to claim 1, wherein the rectifying plate has a square mesh shape in the opening.   The liquid ejecting head according to claim 1, further comprising a plurality of the head main bodies, wherein the cover is provided continuously around the plurality of head main bodies.   The airflow generation means for generating an airflow along the surface direction of the liquid ejection surface is provided between the rectifying plate and the liquid ejection surface, according to any one of claims 1 to 4. Liquid jet head.   The liquid jet head according to claim 5, wherein the air flow generation unit generates a gas flow of moisture.   A liquid ejecting head unit comprising two or more liquid ejecting heads according to claim 1.   A liquid ejecting apparatus comprising the liquid ejecting head according to claim 1.   A liquid ejecting apparatus comprising the liquid ejecting head unit according to claim 7.

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