JP2014188925A - Liquid jet apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a liquid jet apparatus capable of suppressing generation of swirl at a head lower space which is between a record head and a medium and which creates air flow from outside between the record head and the medium, and suppressing generation of wind ripple or the like due to small liquid droplet floating in the head lower space for reducing contamination of the medium to the extent possible.SOLUTION: The liquid jet apparatus comprises: a liquid jet head having a nozzle array 1A having plural nozzle openings 11 arranged thereon; and air flow generation means for generating air flow W between a nozzle plate and a medium so as to suppress swirl generated by air flow formed caused by discharge of liquid droplets without affecting to impact of main droplets among the liquid droplets to be discharged toward the medium which is a printing target from the nozzle opening 1A.

Description

  The present invention relates to a liquid ejecting apparatus, and is particularly useful when applied to a liquid ejecting apparatus in which a liquid ejecting head having a high-density nozzle array in which the interval between adjacent nozzle openings is narrow.

  As a representative example of a liquid ejecting head that is mounted on a liquid ejecting apparatus and ejects liquid through a nozzle opening, for example, an ink jet recording head (hereinafter referred to as “recording”) that ejects ink droplets from nozzles using pressure due to displacement of a piezoelectric actuator. Also known as “head”. In this type of recording head, generally, a piezoelectric actuator is provided on one side of a flow path forming substrate in which a pressure generating chamber communicating with a nozzle opening is formed, and ink in the pressure generating chamber is added by deforming the piezoelectric actuator. Ink droplets are ejected from the nozzle openings.

  The liquid ejecting apparatus includes a serial type liquid ejecting apparatus that performs printing while moving the liquid ejecting head in the main scanning direction with respect to an ejected medium such as a recording sheet such as paper, and the width direction of the recording medium. A line-type liquid ejecting apparatus that performs printing simply by fixing a liquid ejecting head provided with nozzle openings 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, in a recording head having a high-density nozzle row in which the interval between adjacent nozzle openings is narrow, ink droplets are ejected through the nozzle openings. The generated airflow forms a vortex due to a synergistic effect between adjacent nozzle openings. On the other hand, when ink droplets are ejected from the nozzle openings, in addition to the main droplets (main droplets) that are landed on the medium and constitute the target printing or the like, small droplets (hereinafter referred to as “ Also referred to as “satellite drops”) and floats between the nozzle plate and the medium. As a result, the satellite droplets are wound up by the vortex, and irregularly adhere to the medium, thereby causing print stains called wind ripples, resulting in a decrease in print quality. The formation of the wind pattern is also promoted by an airflow generated as the medium and the liquid ejecting head move relatively.

  In order to solve such a problem, a hood that covers from the nozzle opening to the vicinity of the medium to be ejected 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. There has been proposed a drawing head device that suppresses a phenomenon in which satellite droplets land at positions different from the main droplets due to the airflow generated by (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 the hood is only provided on the recording head, turbulent air flow engulfed by the hood is generated, and the satellite droplets land at positions different from the main droplets of the ejection target medium. As a result, the meniscus is destroyed. Such a problem becomes prominent particularly when the relative moving speed of the recording head and the ejection target medium is increased and high-speed printing is performed by increasing the frequency of the drive signal that defines the ejection period of the ink droplets.

  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 the above prior art, the present invention generates an air flow from the outside between the recording head and the medium to suppress the generation of vortices in the space under the head between the recording head and the medium, thereby reducing the space under the head. It is an object of the present invention to provide a liquid ejecting apparatus capable of suppressing the occurrence of a wind pattern or the like due to a small droplet that floats and reducing the contamination of a medium as much as possible.

An aspect of the present invention that achieves the above object includes a liquid ejecting head including a nozzle row in which a plurality of nozzle openings are arranged in parallel, and droplets discharged from the nozzle openings toward a medium to be printed. Among them, an air flow is generated between the nozzle plate and the medium so as to suppress the vortex generated by the air flow formed due to the discharge of the droplet without affecting the landing of the main droplet. The liquid ejecting apparatus includes an airflow generation unit.
According to this aspect, the generation of vortices in the space under the head due to the discharge of droplets is made possible by flowing the air flow from the outside by the air flow generating means in the space under the head that is the space between the nozzle plate and the medium. Can be prevented. As a result, it does not affect the landing of the main droplets that are originally ejected toward the medium, and the occurrence of printing stains such as wind ripples accompanying the landing of small droplets floating in the space under the head on the medium is good. Can be suppressed.

  Here, it is preferable that the air flow is supplied from a direction crossing the nozzle row. In this case, small droplets floating between adjacent nozzle openings in the nozzle row can be effectively stirred. Incidentally, a vortex that causes a wind ripple or the like is formed in a gap between adjacent nozzle openings in the nozzle row. Therefore, it is most effective when the direction of the air flow generated between the nozzle plate and the medium is generated so as to be orthogonal to the nozzle row.

  When the airflow generating means is disposed in the main body of the liquid ejecting apparatus on either side of the liquid ejecting head with respect to the medium transporting direction, the airflow generating means is in the medium transporting direction. On the other hand, it is conceivable that the liquid ejecting head is disposed on both sides of the liquid ejecting head on the main body of the liquid ejecting apparatus.

  Further, the air flow generation means may be disposed integrally with the liquid ejecting head on either side of the liquid ejecting head with respect to the transport direction of the medium, or in the transport direction of the medium. On the other hand, the liquid ejecting head may be integrally disposed on both sides of the liquid ejecting head.

  Further, the liquid ejecting head moves in a direction perpendicular to the medium transport direction, and the air flow generating means supplies an air flow in a direction opposite to the moving direction of the liquid ejecting head. Is desirable. In this case, the direction of the air flow formed due to the air resistance due to the movement of the liquid ejecting head and the direction of the air flow formed by the air flow generating means coincide with each other. It is possible to suppress the printing surface from being damaged.

1 is a schematic perspective view illustrating a configuration of a liquid ejecting apparatus according to a first embodiment. It is explanatory drawing which shows the relationship between the nozzle row | line | column of a liquid ejecting head, and the direction of airflow. It is a block diagram which shows the structure of the control system of a liquid ejecting apparatus. FIG. 4 is an explanatory diagram illustrating a relationship between a recording head moving direction and an airflow generation direction. It is a characteristic view which shows the relationship between the speed | velocity | rate of an air flow, and the landing deviation amount of a satellite. FIG. 6 is a schematic configuration diagram illustrating a configuration of a liquid jet head according to a second embodiment.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
<First Embodiment>
FIG. 1 is a schematic perspective view showing the configuration of the liquid ejecting apparatus according to the first embodiment of the invention. As shown in the figure, an ink jet recording apparatus (hereinafter also referred to as “recording apparatus”) I according to the present embodiment is a so-called mounted recording head 1 that moves along a main scanning direction X and performs predetermined printing. It is a serial type device. Here, the recording head 1 is detachably provided with an ink cartridge 2 that constitutes an ink supply means, and is mounted on a carriage 3 and axially (main scanning direction X) on a carriage shaft 5 attached to the apparatus body 4. It is provided to be movable. For example, the recording head 1 ejects a black ink composition and a color ink composition.

  The apparatus main body 4 is partially hollow in FIG. 1 to indicate the inside of the apparatus main body 4, but has a hollow box shape and is fed with a recording sheet S as a printing medium. A mouth and a paper outlet are provided.

  The ink jet recording apparatus I is provided with a control unit 110 that is a control unit that controls the operation of the recording apparatus I, as will be described in detail later.

  The driving force of the driving motor 6 is transmitted to the carriage 3 via pulleys 6 a and 6 b, a plurality of gears (not shown) and a timing belt 7, so that the carriage 3 on which the recording head 1 is mounted follows the carriage shaft 5. Moved. On the other hand, the apparatus body 4 is provided with a platen 8 along the carriage shaft 5, and a recording sheet S which is a recording medium such as paper fed by a paper feed roller (not shown) is wound around the platen 8. It is conveyed in the sub-scanning direction Y.

  The fan 23 which is an air flow generating means has air blowing ports (not shown) on opposite sides, and forms an air flow toward the recording head 1 side and an air flow toward the opposite side of the recording head 1 side. More specifically, the fan 23 is caused by the ejection of the ink droplets without affecting the landing of the main droplets among the ink droplets ejected from the nozzle openings of the recording head 1 toward the recording sheet S. An air flow is generated between the nozzle plate of the recording head 1 and the recording sheet S (hereinafter referred to as “head under space”) so as to suppress the vortex generated by the formed air flow. That is, as shown in FIG. 2, the nozzle row 1 </ b> A formed on the nozzle plate of the recording head 1 (having four head units for K, C, M, and Y in this example) has a nozzle opening 11. Are juxtaposed in the sub-scanning direction. In this embodiment, the airflow W formed by the fan 23 (see FIG. 1) is supplied so as to be orthogonal to the nozzle row 1A. Thus, it is not essential to form the airflow W so as to be orthogonal to the nozzle row 1A. If the airflow W is formed so as to intersect, there is an effect of suppressing the generation of vortices in the space below the head. However, the generation of vortices can be most effectively suppressed when the relationship is orthogonal.

  The recording head 1 is provided with a flow path communicating with the nozzle opening 11 inside, and the ink filling the inside of a pressure generating chamber (not shown) causes a pressure change by the pressure generating means, whereby the ink is discharged from the nozzle opening 11. Discharge drops. Here, as the pressure generating means for causing the pressure change in the pressure generating chamber, for example, a piezoelectric actuator using a piezoelectric element having a piezoelectric material exhibiting an electromechanical conversion function, or a heat generating element arranged in the pressure generating chamber to generate heat. Ink droplets are ejected from the nozzle openings 11 by bubbles generated by the heat generated by the element, or static electricity is generated between the diaphragm and the electrode, and the diaphragm is deformed by electrostatic force to change the pressure in the pressure generating chamber. A so-called electrostatic actuator that causes ink droplets to be ejected from the nozzle openings 11 can be used.

  According to the recording apparatus I of this embodiment, it is possible to flow an airflow from the fan 23 to the space under the head. As a result, it is possible to prevent as much as possible the generation of vortices in the space under the head due to the ejection of ink droplets. As a result, it does not affect the landing of the main droplets that are originally ejected toward the medium, and the occurrence of printing stains such as wind ripples due to the landing of satellite droplets floating in the space under the head on the medium is improved. Can be suppressed.

  Next, the control system of the recording apparatus I as described above will be described based on FIG. 3 which is a block diagram showing the control system of the recording apparatus according to the first embodiment of the present invention. As shown in the figure, a control unit 110 that controls the recording apparatus I is provided in the control system. The control unit 110 includes a CPU 111, a device control unit 112, and a head control unit 113 that is a drive circuit for the piezoelectric element 300 that is a capacitive load.

  Here, when a signal indicating movement of the carriage 3 (see FIG. 1) is input from the CPU 111 to the apparatus control unit 112, the apparatus control unit 112 drives the drive motor 6 to move the carriage 3 along the carriage shaft 5. While moving in the main scanning direction X, a signal indicating conveyance of the recording sheet S (see FIG. 1) from the CPU 111 is input to the apparatus control unit 112, and the apparatus control unit 112 drives a supply roller (not shown). The recording sheet S is conveyed in the sub-scanning direction Y. The CPU 111 also controls driving of the fan 23 via the device control unit 112. Specifically, the rotation speed and rotation direction of the fan 23 are controlled. The number of rotations defines the amount of air supplied to the space below the head, and the direction of rotation defines whether the air is directed toward the recording head 1 or the other side. Here, the rotation direction is detected by detecting the rotation direction of the drive motor 6 to detect the movement direction of the carriage 3 with respect to the main scanning direction X. Based on the detected data, the CPU 111 defines the rotation direction. Thus, the rotation direction of the fan 23 is defined in a predetermined direction.

  FIG. 4 is an explanatory diagram showing the relationship between the moving direction of the recording head 1 and the direction of airflow generation. The recording apparatus I shown in FIG. 1 is represented as an embodiment shown in FIGS. 4 (a) and 4 (b). That is, when the carriage 3 moves from the left side to the right side in the figure along the main scanning direction X with respect to the apparatus body 4 (see FIG. 1; the same applies hereinafter), an air flow (“wind” in the figure; the same applies hereinafter) is generated. The fan 23 is rotationally driven so as to flow from the right side to the left side. As a result, the airflow from the right side to the left formed by the air resistance accompanying the movement of the carriage 3 and the airflow formed by the fan 23 are superimposed and flow in the space under the head from the right to the left. Such an air flow can satisfactorily prevent the generation of a vortex in the space under the head accompanying the ejection operation of the recording head 1. As a result, it is possible to prevent the satellite droplets from being rolled up due to the eddy current that causes the occurrence of wind ripples, and to obtain good print quality.

  When the moving direction of the carriage 3 is reversed in the recording apparatus I, the direction of the air flow by the fan 23 may be reversed by reversing the rotation direction of the fan 23.

  The fan may be disposed at the left end portion of the apparatus main body 4. That is, the positional relationship between the carriage 3 and the fan 24 can be arranged as shown in FIGS. 4C and 4D. 4C and 4D also, the rotation direction of the fan 24 is controlled so that the direction of the airflow formed by the movement of the carriage 3 and the direction of the airflow formed by the fan 24 are the same. .

  As shown in FIGS. 4E and 4F, the fans 23 and 24 may be disposed at both left and right ends of the apparatus main body 4. In this case, as shown in FIG. 4 (e), when the carriage 3 moves rightward in the figure, the fan 23 is rotated forward and the fan 24 is rotated reversely so that the airflow is directed in the direction of “wind” shown in the figure. Is generated. Further, as shown in FIG. 4 (f), when the carriage 3 moves in the left direction in the figure, the fan 23 is rotated in the reverse direction, the fan 24 is rotated in the forward direction, and the airflow is generated in the direction of “wind” shown in the figure. generate. As a result, an air flow similar to that shown in FIGS. 4A to 4D can be formed.

  FIG. 5 is a characteristic diagram showing the relationship between the velocity of the airflow and the amount of landing deviation of the satellite. As shown in the figure, the satellite droplet separated from the main droplet has a smaller displacement amount (Y displacement amount) in the sub-scanning direction Y as the velocity of the airflow in the head lower space (PG space) increases. I understand. As parameters in this case, the printing frequency of the recording head 1, the interval between the nozzle openings 11 in the nozzle row 1A (see FIG. 2), the gap of the PG space, the scanning speed of the carriage 3, etc. can be considered. By measuring the airflow speed between the PGs in advance and storing the data in the RAM of the CPU 111, the rotational speed of the fan 23 and the like is appropriately controlled based on the data, so It can be seen that generation of wind ripples can be satisfactorily suppressed by satisfactorily suppressing the generation of vortices and reducing the amount of Y misalignment.

<Second Embodiment>
FIG. 6 is a schematic configuration diagram illustrating a configuration of a liquid jet head according to the second embodiment of the present invention that is extracted. As shown in the figure, in this embodiment, fans 25 and 26 which are airflow generating means are integrally formed with the recording head 1 via a carriage 3. Here, the fans 25 and 26 are disposed on both sides in the main scanning direction X, and when one (for example, the fan 25) rotates forward, the other (for example, the fan 26) is driven to rotate in the reverse direction. (See FIG. 3). In addition, guide members 27 and 28 for guiding an air current to a space below the head, which is a space between the nozzle surface 1B of the recording head 1 and the surface of the recording sheet S, are integrated with the openings at the lower ends of the fans 25 and 26. Fixed.

  Here, when the fans 25 and 26 are rotated forward, an air flow directed from the fans 25 and 26 toward the head lower space forms an air flow directed outward from the head lower space at the time of reverse rotation. Thus, when the fan 25 rotates in the forward direction, an air flow from the right side to the left side is formed in the space under the head when the fan 26 rotates in the reverse direction. When the fan 26 rotates forward and when the fan 25 rotates in the reverse direction, the left side in the drawing. An air flow toward the right side is formed. The former is the same as the mode shown in FIG. 4E, and in this mode, the carriage 3 is moved from the left side to the right side in the drawing. On the other hand, the latter is a case similar to the mode shown in FIG. 4F, and in this mode, the carriage 3 is moved from the right side to the left side in the drawing. Such rotation and movement control is performed in the control system shown in FIG. 3 by adjusting the rotation direction of the fans 25 and 26 by the device control unit 112 in accordance with the movement direction of the carriage 3 detected by detecting the rotation direction of the drive motor 6. This is performed by appropriately controlling.

  In this embodiment, the fans 25 and 26 are arranged on both sides of the recording head 1, but of course either one may be used. In this case, the relationship between the direction of movement of the carriage 3 and the direction of airflow is the same as in the state shown in FIGS. 4A and 4B, or FIG. 4C and FIG. In addition, it is possible to prevent the generation of wind ripples by suppressing the generation of eddy currents in the space under the head. Here, the airflow in the space under the head is set to an airflow that does not affect the landing of the main ink droplets discharged from the recording head 1 onto the recording sheet S, so that the rotational speed of the fan 23 and the like is controlled. Can be realized easily.

(Other embodiments)
Although the embodiment of the present invention has been described above, the basic configuration of the present invention is not limited to the above-described one. For example, in the embodiment shown in FIG. 1, the recording head 1 is mounted on the carriage 3 that moves in the direction (main scanning direction X) intersecting the conveyance direction of the recording sheet S, and the recording head unit is moved in the main scanning direction. However, this is a so-called serial type ink jet recording apparatus that performs printing, but is not limited thereto. Of course, it may be a so-called line-type ink jet recording apparatus that performs printing only by transporting the recording sheet S with the recording head fixed.

  In the above embodiment, the ink jet recording apparatus has been described as an example of the liquid ejecting apparatus. However, the present invention is widely applicable to all liquid ejecting apparatuses having a liquid ejecting head, and other than ink. Of course, the present invention can also be applied to a liquid ejecting apparatus including a liquid ejecting head that ejects liquid. 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 bioorganic matter ejection head used for biochip production, and the like.

  I recording apparatus (inkjet recording apparatus), 1 recording head, 1A nozzle row, 3 carriage, S recording sheet, 11 nozzle opening, 23-26 fan, 110 control unit, 112 device control unit, 113 head control unit, 300 piezoelectric element

Claims (7)

  It has a liquid ejecting head having a nozzle row in which a plurality of nozzle openings are arranged side by side, and affects the landing of main drops among liquid droplets ejected from the nozzle openings toward a medium to be printed. And a liquid flow generating means for generating an air flow between the nozzle plate and the medium so as to suppress a vortex generated by the air flow formed due to the discharge of the droplets. Injection device. The liquid ejecting apparatus according to claim 1,
The liquid ejecting apparatus according to claim 1, wherein the air flow is supplied from a direction crossing the nozzle row. The liquid ejecting apparatus according to claim 1 or 2,
The liquid ejecting apparatus according to claim 1, wherein the air flow generation unit is disposed on a main body of the liquid ejecting apparatus on either side of the liquid ejecting head with respect to a conveyance direction of the medium. The liquid ejecting apparatus according to claim 1 or 2,
The liquid ejecting apparatus according to claim 1, wherein the air flow generation unit is disposed on a main body of the liquid ejecting apparatus on both sides of the liquid ejecting head with respect to a conveyance direction of the medium. The liquid ejecting apparatus according to claim 1 or 2,
The liquid ejecting apparatus according to claim 1, wherein the airflow generation unit is integrally disposed on the liquid ejecting head on either side of the liquid ejecting head with respect to a conveyance direction of the medium. The liquid ejecting apparatus according to claim 1 or 2,
The liquid ejecting apparatus according to claim 1, wherein the air flow generation unit is integrally disposed on the liquid ejecting head on both sides of the liquid ejecting head with respect to a conveyance direction of the medium. In the liquid ejecting apparatus according to any one of claims 1 to 6,
The liquid ejecting head moves in a direction orthogonal to the conveyance direction of the medium,
The liquid ejecting apparatus according to claim 1, wherein the air flow generation unit supplies an air flow in a direction opposite to a moving direction of the liquid ejecting head.

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