JP2017177417A - Printer, printing method, and head unit - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a printer that can reduce adhesion of mist on a liquid ejecting surface and occurrence of low-quality printing.SOLUTION: A printer comprises: a head unit 16 including a linear inkjet head 11 having a liquid ejecting surface 12 disposed on the surface opposite to a print medium 3 to eject liquid from a nozzle array 14 disposed on the liquid ejecting surface; a sheet transporting motor 38 to transport the print medium 3; plasma actuators 20 to generate an airflow to a platen gap; and a controller 30 to control liquid ejection from the nozzle array 14, generation of an airflow by the plasma actuators 20, and transport of the print medium 3 by the sheet transporting motor 38.SELECTED DRAWING: Figure 3

Description

  The present invention relates to a printing apparatus, a printing method, and a head unit.

Conventionally, ink mist that floats without reaching the printing medium etc. out of the ink ejected from the ink jet head stays in the gap between the ink ejecting surface and the platen and adheres to the ink ejecting surface, resulting in poor printing. It was known to cause.
There is a large resistance between the ink ejection surface and the platen, and there is little air flow. For this reason, there is a problem that the mist staying between the platen gaps adheres by a self-jet flow of ink jetting and the printing reliability is impaired.
For this reason, conventionally, there has been disclosed a technique in which an airflow is generated between the platen gaps so that mist does not adhere to the head (see, for example, Patent Document 1). Further, a technique is disclosed in which mist is not attached to the head by sucking an airflow below the platen (see, for example, Patent Document 2).

Japanese Patent No. 5467630 JP 2007-038437 A

However, each of the above prior arts requires a large airflow generation device, and there is a problem that the size of the printer itself becomes large.
The present invention has been made in view of the above-described circumstances, and provides a printing apparatus, a printing method, and an inkjet head capable of reducing the occurrence of defective printing by reducing the adhesion of mist to a liquid ejection surface. For the purpose.

In order to achieve the above object, a printing apparatus according to the present invention includes a head unit including a line-like inkjet head that ejects liquid from a nozzle array that opens to a liquid ejection surface that is disposed on a surface facing a print medium; A print medium transport unit that transports the print medium; a plasma actuator that generates an air flow with respect to a platen gap; a liquid jet from the nozzle row; an air flow generation of the plasma actuator; and the printing by the print medium transport unit. And a control unit that controls conveyance of the medium.
According to this configuration, by driving the plasma actuator to generate an air flow, the air in the platen gap can easily move, and mist around the liquid ejection surface can be discharged. Thereby, it becomes difficult for mist to adhere to the liquid ejection surface, and the occurrence of printing defects can be reduced. In addition, by providing the plasma actuator, it is not necessary to provide a separate large-scale airflow generation device, and the equipment cost can be reduced.

In the invention, the plasma actuator is disposed on the liquid ejection surface.
According to this configuration, the mist around the liquid ejection surface can be efficiently discharged.

In the present invention, the plasma actuator is arranged alongside the nozzle row.
According to this configuration, it is possible to generate an air flow in the conveyance direction of the print medium, and it is possible to discharge mist in the same direction as the conveyance direction of the print medium or in the opposite direction.

In the invention, the plasma actuator is disposed on a support member of the ink jet head.
According to this configuration, by driving the plasma actuator, an air flow can be generated by the support member, and thereby, mist around the liquid ejection surface can be discharged.

In the invention described above, the plasma actuator is arranged at a position farther than a distance between the liquid ejecting surface and the print medium.
According to this configuration, an air flow can be generated at a position away from the liquid ejection surface, and mist can be discharged by this air flow.

In the present invention, the plasma actuator is disposed on a surface intersecting the liquid ejecting surface.
According to this configuration, by driving the plasma actuator, an air flow can be generated in a direction toward or away from the print medium, and mist can be discharged by this air flow.

Moreover, in the said invention, the airflow generation area | region by the said plasma actuator is an area | region longer than the length of the said nozzle row, It is characterized by the above-mentioned.
According to this configuration, it is possible to secure the airflow generation region by the plasma actuator in a region longer than the length of the nozzle row, and it is possible to reliably discharge mist generated from the nozzle row.

In the invention described above, the ink jet head is configured by arranging a plurality of unit ink jet heads in a staggered manner.
According to this configuration, even when the line-type inkjet head is configured by arranging the unit inkjet heads in a staggered manner, the mist around the liquid ejection surface of each unit inkjet head can be discharged. it can.

In the invention described above, the plasma actuator is arranged for each unit ink jet head.
According to this configuration, since the plasma actuator can be driven for each unit inkjet head, the mist around the liquid ejection surface of each unit inkjet head can be reliably discharged.

In the present invention, the plasma actuator includes a plurality of plasma actuators arranged side by side.
According to this configuration, by arranging a plurality of plasma actuators, it is possible to drive the plasma actuators corresponding to the nozzle holes ejecting ink.

Further, in the invention, the control unit prevents the liquid droplets that float without reaching the print medium generated by ejecting liquid from the nozzle row from staying around the liquid ejecting surface. A plasma actuator is driven to generate an air flow.
According to this configuration, it is possible to discharge the liquid droplets that do not reach the print medium generated by ejecting the liquid from the nozzle row and do not stay around the liquid ejecting surface.

In the invention described above, the control unit may drive the plasma actuator to generate an airflow in the same direction as or in the opposite direction to the transport direction of the print medium.
According to this configuration, it is possible to efficiently discharge mist by generating an air flow in the same direction as the print medium conveyance direction or in the opposite direction.

In the present invention, the control unit drives the plasma actuator to generate an air flow when liquid is not ejected from the nozzle row.
According to this configuration, an air flow is generated when the liquid is not ejected. For example, when printing with high precision ink is required, such as when printing in the high-definition printing mode, the ink is required. The landing accuracy can be further improved.

In the invention, the control unit does not drive the plasma actuator when the liquid is ejected from the nozzle row for printing.
According to this configuration, since air current is not generated when the liquid is ejected, the ink can be used when high accuracy ink landing accuracy is required, for example, when printing in the high-definition print mode. The landing accuracy can be further improved.

In the invention, the control unit drives the plasma actuator to generate an air flow during a flushing operation.
Since mist is generated when ink is ejected by the flushing operation, the ink ejection amount is limited to reduce the amount of mist. According to this configuration, the mist is discharged by driving the plasma actuator during the flushing operation. Therefore, the restriction can be relaxed, such as flushing all nozzle rows at the same time, and the throughput can be improved.

In the invention described above, a drive voltage generation unit that generates a drive voltage for driving the plasma actuator is further provided, and the drive voltage generation unit is mounted on the head unit.
According to this configuration, it is possible to generate the driving voltage for the plasma actuator driven with a high voltage by the driving voltage generation unit. Therefore, it is not necessary to lay high voltage wiring on a flexible cable or the like, and problems such as insulation, short circuit countermeasures, noise countermeasures, etc. do not occur.

In the invention, the head unit includes a wiring for supplying an inkjet driving voltage for driving the inkjet head, and the driving voltage generation unit generates a voltage for driving the plasma actuator from the inkjet driving voltage. It is characterized by doing.
According to this configuration, since the voltage for driving the plasma actuator is generated from the ink jet drive voltage supplied by the wiring, it is not necessary to lay a dedicated wiring for the plasma actuator.

Moreover, in the said invention, the said plasma actuator is comprised so that attachment or detachment is possible, It is characterized by the above-mentioned.
According to this configuration, the plasma actuator can be easily replaced when it is contaminated with a mist or when it is broken.

In the invention described above, a filter for collecting the mist is provided downstream of the air flow generated by the plasma actuator, and the filter is detachable.
According to this structure, the mist discharged | emitted by driving a plasma actuator can be collect | recovered with a filter. In addition, by making the filter detachable, it can be easily replaced when the filter becomes dirty.

The printing method of the present invention is a printing apparatus that performs printing by ejecting liquid onto a print medium conveyed by a print medium conveyance unit from a nozzle row that opens on a liquid ejection surface of a line-shaped inkjet head. And a plasma actuator is driven to generate an air flow with respect to the platen gap of the printing apparatus.
According to this configuration, by driving the plasma actuator to generate an air flow, the air in the platen gap can easily move, and mist around the liquid ejection surface can be discharged. Thereby, it becomes difficult for mist to adhere to the liquid ejection surface, and the occurrence of printing defects can be reduced. In addition, by providing the plasma actuator, it is not necessary to provide a separate large-scale airflow generation device, and the equipment cost can be reduced.

According to another aspect of the present invention, there is provided a line including: a liquid ejecting surface disposed on a surface facing the print medium; and a nozzle array that opens to the liquid ejecting surface and ejects liquid onto the print medium. The ink jet head includes a plasma actuator, and the plasma actuator generates an air flow in a space in which the nozzle row ejects liquid.
According to this configuration, by driving the plasma actuator to generate an air flow, the air in the space in which the nozzle row ejects the liquid can easily move, and mist around the liquid ejection surface can be discharged. Thereby, it becomes difficult for mist to adhere to the liquid ejection surface, and the occurrence of printing defects can be reduced. In addition, by providing the plasma actuator, it is not necessary to provide a separate large-scale airflow generation device, and the equipment cost can be reduced.

1 is a diagram illustrating an outline of a printing apparatus according to a first embodiment. It is the schematic of a head unit. FIG. 3 is a schematic view seen from the liquid ejection surface side of FIG. 2. It is sectional drawing which shows the basic structure of a plasma actuator. The figure which shows the example which produces an airflow in the same direction as the conveyance direction of a printing medium. The figure which shows the example which generates the airflow which flows into a nozzle row direction mutually. The figure which shows the example which generates the airflow which flows in the direction away from a nozzle row mutually. The figure which shows the example which produces an airflow in the direction away from a nozzle row. The figure which shows the example which generates an airflow in the direction which goes to a nozzle row. The figure which shows the example which generate | occur | produces the airflow which flows into the cross direction of printing medium conveyance. The figure which shows the example which generate | occur | produces the airflow which flows into the cross direction of printing medium conveyance. The figure which shows the example which generate | occur | produces the airflow which flows into the cross direction of printing medium conveyance. The figure which shows the example which generate | occur | produces the airflow which flows into the cross direction of printing medium conveyance. The figure which shows the example which mounted the plasma actuator in the support member. The figure which shows the modification of the arrangement structure of a plasma actuator. The figure which shows the example which generates the airflow which goes to the printing medium side. The figure which shows the example which generates the airflow which leaves | separates from the printing medium side. FIG. 3 is a block diagram illustrating a functional configuration of the printing apparatus. The timing chart which shows a drive timing. It is a figure which shows the example of arrangement | positioning by a unit inkjet head. It is a figure which shows the example of arrangement | positioning of a some plasma actuator. It is the schematic of the head unit which shows 2nd Embodiment.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is a schematic diagram of a printing apparatus according to the first embodiment. FIG. 2 is a schematic diagram illustrating the head unit of the printing apparatus according to the first embodiment. FIG. 3 is a schematic view seen from the liquid ejection surface side of FIG.

As shown in FIG. 1, the printing apparatus 1 is an inkjet line printer and includes a flat platen 2. A predetermined print medium 3 is conveyed on the upper surface of the platen 2 in the sub-scanning direction by the print medium conveyance unit. The platen 2 may be provided with an ink discarding area during borderless printing.
Examples of the print medium 3 include roll paper wound in a roll shape, a cut sheet cut into a predetermined length, and a continuous sheet in which a plurality of sheets are connected. These recording media are sheets such as plain paper, copy paper, cardboard, and the like, and sheets made of synthetic resin, and these sheets can be used after coating or infiltration processing. In addition, as a form of the cut sheet, for example, in addition to a standard size cut paper such as PPC paper or a postcard, a booklet form in which a plurality of sheets such as a passbook are bound, or a bag shape such as an envelope Is mentioned. Moreover, as a form of a continuous sheet, for example, continuous paper in which sprocket holes are formed at both ends in the width direction and folded at a predetermined length can be cited.

Above the platen 2, a support member 10 is provided that extends in a direction that intersects the conveyance direction of the print medium 3. The support member 10 includes a line-shaped head unit 16.
The surface of the inkjet head 11 that faces the platen 2 is a liquid ejection surface 12. On the liquid ejecting surface 12, a nozzle row 14 is formed that is open to the liquid ejecting surface 12 and includes a plurality of nozzle holes 13 that eject a liquid such as ink onto the print medium 3. Here, the gap (space) between the liquid ejection surface 12 and the platen 2 or the gap (space) between the liquid ejection surface 12 and the print medium 3 is collectively referred to as a platen gap.
The ink jet head 11 includes a driving element such as a piezo element for ejecting liquid from the nozzle hole 13. In addition, an ink cartridge 15 that supplies ink to the inkjet head 11 is mounted on the support member 10.
The ink jet head 11, the ink cartridge 15, and the support member 10 constitute a head unit 16.
In the present embodiment, a case where a single color ink cartridge 15 is used and ink is used as a liquid will be described as an example. Further, the ink cartridge 15 may be disposed at a place other than the head unit 16.

  Further, for example, a flushing area (not shown) of the inkjet head 11 is provided below the platen 2. The platen 2 is configured to be retractable from below the inkjet head 11. Then, in a state where the platen 2 is retracted, ink is ejected from the nozzle holes 13 of the inkjet head 11 to discharge the thickened ink. A gap between the flushing area 17 and the liquid ejection surface 12 is also referred to as a platen gap.

Two plasma actuators 20 are disposed on both surfaces of the liquid ejecting surface 12 of the inkjet head 11 facing the platen 2 at both ends of the print medium 3 in the transport direction of the print medium, with the nozzle row 14 interposed therebetween. Each plasma actuator 20 is formed longer than the length of the nozzle row 14.
In general, the platen gap is narrow and may be 1 mm or less. Therefore, as shown in FIG. 2, the plasma actuator 20 needs to be disposed on a surface that is one step deeper than the surface on which the nozzle row 14 is disposed. This deep surface also corresponds to the liquid ejection surface 12. The plasma actuator 20 may be embedded in the inkjet head 11 to eliminate the step, or may be disposed on a surface farther than the distance between the nozzle row 14 and the platen 2.

  FIG. 4 is a cross-sectional view showing the basic structure of the plasma actuator 20. As shown in FIG. 4, the plasma actuator 20 includes two thin film electrodes 21a and 21b and a dielectric layer 22 sandwiched between the electrodes 21a and 21b. By applying an alternating voltage of several kV and a frequency of several kHz between the two electrodes 21a and 21b, a plasma discharge 23 is generated at a portion sandwiched between the upper electrode 21a and the dielectric 22, thereby An airflow that flows from the upper electrode 21a toward the lower electrode 21b is generated. The plasma actuator 20 can easily control the generation, stop, or air velocity of the air current by controlling the application of the alternating voltage. This is a feature that is difficult to realize with an airflow generator such as a fan. Two thin film electrodes 21b may be prepared and arranged so as to sandwich the electrode 21a. In this way, if one side of the two electrodes 21b is selected, the direction of air flow generation can be controlled in both forward and reverse directions.

The plasma actuator 20 is arranged so as to generate an airflow along the conveyance direction of the print medium 3. In the present embodiment, each plasma actuator 20 is composed of two plasma actuators 20 arranged so that the direction of airflow generation is opposite to each other.
With this configuration, an airflow can be generated in any direction of the conveyance direction of the print medium 3 on one side of the nozzle row 14.

  In addition, arrangement | positioning of the plasma actuator 20 is not limited to this, The generation | occurrence | production direction of airflow is also arbitrary. Further, it may be arranged only on one side of the nozzle row 14 or may be arranged in a direction intersecting with the nozzle row 14. Hereinafter, various arrangements and various airflow generation directions will be exemplified.

FIG. 5 is a diagram illustrating an example in which an airflow is generated in the same direction as the conveyance direction of the print medium 3 by driving the plasma actuator 20.
As shown in FIG. 5, each plasma actuator 20 generates an air flow in the same direction as the conveyance direction of the print medium 3.
By generating the airflow in this way, the air in the platen gap easily moves along with the conveyance of the printing medium 3, and the mist on the liquid ejection surface 12 is discharged. In the head unit 16, Karman vortices are generated on the downstream side in the transport direction of the print medium 3. By driving the plasma actuator 20 in this way, generation of Karman vortices can be suppressed. Thereby, it can reduce that mist is disperse | distributed disorderly in a body by Karman vortex. Further, since the two plasma actuators 20 and 20 generate airflows in the same direction, a strong airflow is generated, and the mist around the liquid ejection surface 12 can be discharged efficiently.
Note that an air flow may be generated on the upstream side in the conveyance direction of the print medium 3. As a result, when the print medium 3 decelerates to stop, the mist around the liquid ejection surface 12 can be discharged, and if the print medium 3 is cut paper, the print medium 3 is soiled with mist. Less likely.

FIG. 6 is a view showing an example in which air currents flowing in the direction of the nozzle array 14 are generated by driving the plasma actuator 20. FIG. 7 is a diagram illustrating an example in which air currents flowing in directions away from the nozzle row 14 are generated by driving the plasma actuator 20.
By generating an air flow as shown in FIG. 6, the mist can be discharged in a direction orthogonal to the conveyance direction of the print medium 3 as indicated by a broken line arrow in FIG. 6. No longer get dirty.
By generating an air current as shown in FIG. 7, the air current flows in from a direction orthogonal to the conveyance direction of the print medium 3 and discharges mist in both directions away from the nozzle row 14 as indicated by the broken line arrows in FIG. 7. Therefore, the discharged mist is not biased to a specific place in the printing apparatus 1.
The plasma actuator 20 may be driven when the print medium 3 is being conveyed, or may be driven when the print medium 3 is not being conveyed.

The plasma actuator 20 may drive only one of the plasma actuators 20.
8 and 9 are diagrams showing an example in which only one plasma actuator 20 (20a, 20b) is driven.
FIG. 8 shows a case where only the plasma actuator 20a located on the downstream side in the transport direction of the print medium 3 is driven.
FIG. 9 shows a case where only the plasma actuator 20b positioned upstream in the transport direction of the print medium 3 is driven. In these cases, only the driving plasma actuator 20 may be mounted, and the non-driving plasma actuator 20 may not be mounted.
By driving the plasma actuator 20 in this way, an air flow can be generated in the same direction as the transport direction of the print medium 3, and mist in the head gap can be efficiently discharged. Further, an air flow may be generated in the direction opposite to the conveyance direction of the print medium 3.

10 to 13 are views showing modifications in which the plasma actuator 20 is also arranged in a direction intersecting with the conveyance direction of the print medium 3.
FIG. 10 shows an example in which air currents in the same direction are generated by the plasma actuators 20a and 20b, and air currents flowing in directions in which the plasma actuators 20c and 20d in the intersecting directions are away from the nozzle row 14 are generated.
By driving the plasma actuator 20 in this way, mist present at various locations in the platen gap can be efficiently discharged without unevenness. Further, since the mist is discharged in three directions, the discharged mist is not biased to a specific place in the printing apparatus.
FIG. 11 shows an example in which air currents in the same direction are generated by the plasma actuators 20 a and 20 b at both ends in the conveyance direction of the print medium 3, and air currents flowing in the directions toward the nozzle rows 14 are generated by the plasma actuators 20 c and 20 d in the intersecting direction. Show.
By driving the plasma actuator 20 in this way, a strong air current can be generated, and the mist in the platen gap can be discharged efficiently.
In the example of FIGS. 10 and 11, the plasma actuators 20 a and 20 b may generate an airflow in a direction opposite to the conveyance direction of the print medium 3.

FIG. 12 shows an example in which the plasma actuators 20a and 20b generate airflow in the direction toward the nozzle row 14 and the plasma actuators 20c and 20d in the intersecting direction generate airflow in the direction away from the nozzle row 14.
By driving the plasma actuator 20 in this way, the mist in the head gap can be efficiently discharged in the direction intersecting the transport direction of the print medium 3, so that the print medium 3 is not soiled by the discharged mist. .
FIG. 13 shows an example in which the plasma actuators 20a and 20b generate an air flow away from the nozzle row 14 and the plasma actuators 20c and 20d in the intersecting direction generate air flow toward the nozzle row 14 with each other.
By driving the plasma actuator 20 in this way, the mist in the head gap can be discharged from both directions away from the nozzle row 14 because the airflow flows from the direction perpendicular to the conveyance direction of the print medium 3 and is discharged. The mist is not biased to a specific place in the printing apparatus.
Note that the plasma actuator 20 may be arranged only in the direction intersecting the transport direction of the print medium 3.

FIG. 14 is a view showing an example in which the plasma actuator 20 is mounted on the support member 10. As shown in FIG. 14, when the plasma actuator 20 is mounted on the support member 10, the plasma actuator 20 is embedded in the support member 10 and arranged. By doing so, it is not necessary to mount the plasma actuator 20 on the ink-jet head 11, so that the structure of the ink-jet head 11 is simplified and manufacture is facilitated.
FIG. 15 is a view showing a modification of the arrangement structure of the plasma actuator 20. As shown in FIG. 15, a step surface 19 is formed on the support member 10 in a direction away from the print medium 3 from the liquid ejection surface of the inkjet head 11, and the plasma actuator 20 is disposed on the step surface 19. May be. Even when the plasma actuator 20 is disposed on the inkjet head 11 as shown in FIG. 2, a stepped surface may be formed on the inkjet head 11 in the same manner.
By doing so, since the distance between the plasma actuator 20 and the platen 2 or the print medium 3 becomes larger than the platen gap, mist can be discharged efficiently. 16 and 17, the surface on which the plasma actuator 20 is disposed can be said to be the liquid ejection surface 12.

FIGS. 16 and 17 are diagrams showing modifications of the arrangement of the plasma actuator 20.
The plasma actuator 20 is disposed on the side surface of the support member 10.
FIG. 16 shows an example in which an air flow directed downward, that is, toward the print medium 3 is generated by the plasma actuator 20.
As shown in FIG. 16, by generating an air flow toward the print medium 3 by the plasma actuator 20, the mist in the platen gap is landed on the surface of the print medium 3 by the generated downward air flow. Mist does not adhere.
FIG. 17 shows an example in which an air flow away from the upper side, that is, the print medium 3 side is generated by the plasma actuator 20.
As shown in FIG. 17, the mist drifting around the liquid ejecting surface 12 can be moved away from the liquid ejecting surface 12 by generating an air flow away from the print medium 3 by the plasma actuator 20. In the examples of FIGS. 16 and 17, the plasma actuator 20 may be mounted on the inkjet head 11.

Next, the control configuration of this embodiment will be described.
FIG. 18 is a block diagram illustrating a functional configuration of the printing apparatus 1 according to the present embodiment.
As illustrated in FIG. 18, the printing apparatus 1 includes a control unit 30 that controls each unit and various motors that drive various motors according to the control of the control unit 30 and that output a detection state of a detection circuit to the control unit 30. And a driver circuit. The various driver circuits include a head driver 32, a carriage driver 33, a plasma actuator driver 34, and a paper feed driver 35.
The control unit 30 centrally controls each unit of the printing apparatus 1. The control unit 30 includes a CPU, an executable basic control program, a ROM that stores data related to the basic control program in a non-volatile manner, a RAM that temporarily stores programs executed by the CPU, predetermined data, and the like, Other peripheral circuits are provided.

The head driver 32 is connected to a driving element 36 such as a piezo element for ejecting ink. The drive element 36 is driven according to the control of the control unit 30 and ejects a necessary amount of ink from the nozzle hole 13.
The plasma actuator driver 34 is connected to the plasma actuator 20, outputs a drive signal to the plasma actuator 20, and drives the plasma actuator 20 by the control unit 30.
The paper feed driver 35 is connected to the paper feed motor 38 and outputs a drive signal to the paper feed motor 38 to operate the paper feed motor 38 by an amount instructed by the control unit 30. In accordance with the operation of the paper feed motor 38, the print medium 3 is transported by a predetermined amount in the transport direction.

In order to drive the plasma actuator 20, a high voltage is required. The printing apparatus 1 includes a drive voltage generation unit 40 that generates a drive voltage for driving the plasma actuator 20. The drive voltage generator 40 is connected to the plasma actuator 20 and the plasma actuator driver 34.
The head unit 16 is provided with a flexible cable for transmitting a head drive signal. It is not preferable to additionally lay high voltage wiring for driving the plasma actuator 20 on the flexible cable because problems such as insulation distance, short circuit countermeasures, noise countermeasures, and the like occur.
Therefore, in this embodiment, the flexible cable is provided with a low-voltage power supply line, and the drive voltage generator 40 is mounted on the head unit 16. The drive voltage generator 40 uses the low voltage power supply as an input voltage and boosts the voltage to a high voltage in the head unit 16.
When a piezo element is used as the drive element 36, since the power supply line for driving the piezo element is laid on the flexible cable, the power source for driving the piezo element is used as the input voltage of the drive voltage generating unit 40. It may be used as Similarly, when a thermal type driving element is used as the driving element 36, the thermal head driving power source can be used as the input voltage of the driving voltage generating unit 40. Of course, an independent low-voltage power line may be laid on the circuit board 41.
If there are no problems such as insulation distance, short circuit countermeasures, noise countermeasures, etc., a high voltage wiring for driving the plasma actuator 20 may be laid on the flexible cable, or a head drive signal may be used for the high voltage wiring. A cable other than the flexible cable to be transmitted may be laid.

The control unit 30 drives and controls the plasma actuator 20 via the plasma actuator driver 34.
FIG. 19 is a timing chart showing the driving timing of the plasma actuator 20 with respect to the printing timing of the inkjet head 11.
As shown in FIG. 19, for example, the control unit 30 starts driving the plasma actuator 20 earlier than the start of ink ejection at the timing of driving the drive element 36 of the inkjet head 11 to eject ink. To control. In addition, the control unit 30 performs control so as to finish driving later than the end of ink ejection.
By driving the plasma actuator 20 earlier than the start of ink ejection in this way, it is possible to discharge the mist that has accumulated before ink ejection and to discharge the mist immediately after the start of ink ejection. Further, the mist staying during printing can be discharged by ending the driving of the plasma actuator 20 later than the end of ink ejection.

Further, the control unit 30 may control the plasma actuator 20 to be driven to generate an air flow when ink is not ejected from the inkjet head 11. That is, when the ink is ejected from the inkjet head 11, the control unit 30 performs control so that the plasma actuator 20 is not driven.
By controlling in this way, for example, when high-precision ink landing accuracy is required, such as when printing in the high-definition print mode, the ink landing accuracy can be further improved.
Further, for example, when the print medium 3 is transported to the printing position, or when flushing is performed in the flushing area, the ink is not ejected and driven. At this time, the plasma actuator 20 may be driven to discharge the mist.

  In particular, during the flushing operation, if the adjacent nozzle rows are driven simultaneously, more mist is generated. Conventionally, the flushing operation has been executed without simultaneously driving the adjacent nozzle rows. By driving the plasma actuator 20 during the flushing operation, the mist can be discharged efficiently, so that all the nozzle rows 14 can be flushed simultaneously, and the throughput can be improved.

Moreover, in the said embodiment, although the example in the case of arrange | positioning the plasma actuator 20 in one inkjet head 11 was demonstrated, this invention is not limited to this.
FIG. 20 is a diagram illustrating an example in which the inkjet head is configured by a plurality of unit inkjet heads 11a. As shown in FIG. 20, the unit inkjet heads 11a may be arranged in a staggered manner, and the plasma actuator 20e may be arranged for each unit inkjet head 11a.
In this case, among each unit inkjet head 11a, there may be a unit inkjet head 11a that ejects ink from the nozzle row 14 and a unit inkjet head 11a that does not eject ink. In such a case, only the plasma actuator 20e corresponding to the unit inkjet head 11a ejecting ink may be driven. Note that the plasma actuators 20 may not be arranged corresponding to the unit inkjet heads 11a.

FIG. 21 is a view showing an example in which the plasma actuator 20 is arranged by arranging a plurality of plasma actuators 20f. As shown in FIG. 21, the same effect can be obtained even when a plurality of plasma actuators 20f are arranged side by side.
In this case, in the inkjet head 11, there may be a nozzle hole 13 that ejects ink from the nozzle row 14 and a nozzle hole 13 that does not eject ink. In such a case, only the plasma actuator 20f corresponding to the nozzle hole 13 ejecting ink may be individually driven.

  Further, the plasma actuator 20 may be unitized and disposed so as to be detachable from the inkjet head 11 or the support member 10.

Next, the printing method of the present invention will be described.
When printing, the control unit 30 controls the head driver 32 and the paper feed driver 35, respectively. Accordingly, the drive element 36 is driven while driving the paper feed motor 38 to transport the print medium 3 in the transport direction, whereby ink is ejected from the nozzle holes 13 and printing is performed on the print medium.

In this case, in the present embodiment, the control unit 30 outputs a drive signal to the plasma actuator 20 to drive the plasma actuator 20. The driving of the plasma actuator 20 may be any of the driving described above.
Accordingly, by driving the plasma actuator 20 to generate an air flow, the air in the platen gap can easily move, and the mist around the liquid ejection surface 12 can be discharged.

  Note that the printing apparatus 1 of this embodiment may include a plurality of head units 16 for color printing. In that case, the mist around the liquid ejection surface 12 of each head unit 16 can be discharged by applying the above-described configuration to each head unit 16.

As described above, the printing apparatus 1 to which the present invention is applied includes the line-shaped inkjet head 11 that ejects liquid from the nozzle row 14 that opens to the liquid ejection surface 12 disposed on the surface facing the print medium 3. The head unit 16 is provided. Further, a paper feed motor 38 (print medium transport unit) that transports the print medium 3 and a plasma actuator 20 that generates an air flow with respect to the platen gap are provided. A control unit 30 that controls liquid ejection from the nozzle row 14, generation of an air current of the plasma actuator 20, and conveyance of the print medium 3 by the paper feed motor 38 is provided.
According to this, by driving the plasma actuator 20 to generate an air flow, the air in the platen gap can easily move, and the mist around the liquid ejecting surface 12 can be discharged. Thereby, it becomes difficult for mist to adhere to the liquid ejection surface 12, and the occurrence of printing defects can be reduced. Moreover, since the plasma actuator 20 is provided, it is not necessary to separately provide a large airflow generation device, and the equipment cost can be reduced.

In one example of the present embodiment, the plasma actuator 20 may be disposed on the liquid ejection surface 12.
According to this, the mist around the liquid ejection surface 12 can be efficiently discharged.

In an example of the present embodiment, the plasma actuator 20 may be arranged side by side with the nozzle row 14.
According to this, airflow can be generated in the transport direction of the print medium 3, and mist can be discharged in the same direction as the transport direction of the print medium 3 or in the opposite direction.

In one example of this embodiment, the plasma actuator 20 may be disposed on the support member 10 of the inkjet head 11.
According to this, by driving the plasma actuator 20, an air flow can be generated by the support member 10, and thereby, mist around the liquid ejecting surface 12 can be discharged.

In an example of the present embodiment, the plasma actuator 20 may be disposed at a position farther than the distance between the liquid ejecting surface 12 and the print medium 3.
According to this, airflow can be generated at a position away from the liquid ejection surface 12, and mist can be discharged by the airflow.

In an example of the present embodiment, the plasma actuator 20 may be disposed on a surface that intersects the liquid ejection surface 12.
According to this, by driving the plasma actuator 20, it is possible to generate an air flow in the direction toward or away from the print medium 3, and the mist can be discharged by this air flow.

In one example of the present embodiment, the airflow generation region by the plasma actuator 20 may be a region longer than the length of the nozzle row 14.
According to this, the air flow generation region by the plasma actuator 20 can be secured in a region longer than the length of the nozzle row 14, and the mist generated from the nozzle row 14 can be reliably discharged.

In one example of the present embodiment, the line-shaped inkjet head may be configured by arranging a plurality of unit inkjet heads 11a in a staggered manner.
According to this, even when the line-shaped inkjet head is configured by arranging the unit inkjet heads 11a in a staggered manner, the mist around the liquid ejecting surface 12 of each unit inkjet head 11a is discharged. be able to.

In one example of the present embodiment, the plasma actuator 20 may be disposed for each unit inkjet head 11a.
According to this, since the plasma actuator 20 can be driven for each unit inkjet head 11a, the mist around the liquid ejection surface 12 of each unit inkjet head 11a can be reliably discharged.

In an example of the present embodiment, the plasma actuator 20 may include a plurality of plasma actuators 20f arranged side by side.
According to this, by arranging a plurality of plasma actuators 20f, it is possible to drive the plasma actuators 20f corresponding to the nozzle holes 13 ejecting ink.

In an example of the present embodiment, the control unit 30 causes the mist generated by ejecting liquid from the nozzle row 14 (droplets that float without reaching the print medium) to stay around the liquid ejecting surface 12. In order to avoid this, the plasma actuator 20 may be driven to generate an air flow.
According to this, by driving the plasma actuator 20 to generate an air flow, the air in the platen gap can easily move, and the mist around the liquid ejecting surface 12 can be discharged. Thereby, it becomes difficult for mist to adhere to the liquid ejection surface 12, and the occurrence of printing defects can be reduced.

In one example of the present embodiment, the control unit 30 may drive the plasma actuator 20 to generate an airflow in the same direction as the conveyance direction of the print medium 3 or in the opposite direction.
According to this, it is possible to efficiently discharge mist by generating an air flow in the same direction as the transport direction of the print medium 3 or in the opposite direction.

In one example of the present embodiment, the control unit 30 may drive the plasma actuator 20 to generate an air flow when liquid is not ejected from the nozzle row 14.
According to this, since the air flow is generated when the liquid is not ejected, for example, when printing in the high-definition printing mode is required, when the landing accuracy of the high-precision ink is required, the ink The landing accuracy can be further improved.
In one example of the present embodiment, the control unit 30 may not drive the plasma actuator 20 when the liquid is ejected from the nozzle row 14 for printing.
According to this, since air current is not generated when the liquid is ejected, for example, when printing with high precision ink is required, such as when printing in the high-definition printing mode, the ink is used. The landing accuracy can be further improved.

In one example of the present embodiment, the control unit 30 may drive the plasma actuator 20 during the flushing operation to generate an air flow.
Since mist is generated when ink is ejected by the flushing operation, the ink ejection amount is limited to reduce the amount of mist. According to this configuration, the mist is discharged by driving the plasma actuator 20 during the flushing operation. Therefore, the restriction can be relaxed, for example, flushing all the nozzle rows 14 at the same time, and the throughput can be improved.

In the example of the present embodiment, a drive voltage generation unit 40 that generates a drive voltage for driving the plasma actuator 20 may be further included, and the drive voltage generation unit 40 may be mounted on the head unit 16.
According to this, the drive voltage generating unit 40 can generate a drive voltage to the plasma actuator 20 driven at a high voltage. Therefore, it is not necessary to lay high voltage wiring on a flexible cable or the like, and problems such as insulation, short circuit countermeasures, noise countermeasures, etc. do not occur.

In one example of the present embodiment, the head unit 16 includes a wiring for supplying an inkjet drive voltage for driving the inkjet head 11, and the drive voltage generation unit 40 is a voltage for driving the plasma actuator 20 from the inkjet drive voltage. May be generated.
According to this, since the voltage which drives the plasma actuator 20 is produced | generated from the inkjet drive voltage supplied by wiring, it is not necessary to lay the wiring for exclusive use of the plasma actuator 20 in a flexible cable.

Moreover, in an example of this embodiment, the plasma actuator 20 may be comprised so that attachment or detachment is possible.
According to this, it is possible to easily replace the plasma actuator 20 when it is contaminated with a mist or the like, or when it has failed.

Next, a second embodiment of the present invention will be described.
FIG. 22 is a schematic view of the head unit 16 showing the second embodiment of the present invention. Note that the same parts as those in the first embodiment are denoted by the same reference numerals and description thereof is omitted.
As shown in FIG. 22, a mist collection container 50 is provided in the conveyance direction of the print medium 3 of the support member 10. The mist collection container 50 is formed with an opening 51 adjacent to the liquid ejection surface 12 of the inkjet head 11.
Inside the mist collection container 50, a plasma actuator 20 that generates an air flow so as to collect mist from the opening 51 is disposed. On the side surface of the mist collection container 50, a filter 52 that collects the mist sent into the mist collection container 50 is disposed.
The filter 52 is detachable. The entire inside of the mist collection container 50 may be filled with a filter 50 such as a sponge, for example.

  When the plasma actuator 20 is driven in the present embodiment, an air flow from the opening 51 toward the filter 52 is generated inside the mist collection container 50 as indicated by an arrow in the figure. Due to this air flow, mist around the liquid ejection surface 12 enters the mist collection container 50 through the opening 51 and is collected by the filter 52.

As described above, in this embodiment, the filter 52 that collects mist is provided downstream of the air flow generated by the plasma actuator 20, and the filter 52 is detachable.
According to this, the mist generated from the nozzle row 14 can be collected by the filter 52 by driving the plasma actuator 20. Further, by making the filter 52 detachable, it can be easily replaced when the filter 52 becomes dirty.

In the second embodiment, the filter 52 is detachable. However, the present invention is not limited to this. For example, the entire mist collection container 50 may be replaceable instead of the filter 52 alone.
The above-described embodiment is merely an example of a specific mode to which the present invention is applied, and the present invention is not limited. The present invention can be applied as a mode different from the above-described embodiment.

  DESCRIPTION OF SYMBOLS 1 ... Printing apparatus, 2 ... Platen, 3 ... Print medium, 10 ... Support member, 11 ... Inkjet head, 12 ... Liquid ejection surface, 13 ... Nozzle hole, 14 ... Nozzle row, 15 ... Ink cartridge, 16 ... Head unit, 20 ... Plasma actuator, 30 ... Control part, 40 ... Drive voltage generation part, 52 ... Filter.

Claims (22)

A head unit including a line-like inkjet head that ejects liquid from a nozzle row that opens to a liquid ejection surface disposed on a surface facing the print medium;
A print medium transport unit for transporting the print medium;
A plasma actuator that generates an airflow against the platen gap;
A printing apparatus comprising: a liquid jet from the nozzle row; an air flow generation of the plasma actuator; and a control unit that controls conveyance of the print medium by the print medium conveyance unit.   The printing apparatus according to claim 1, wherein the plasma actuator is disposed on the liquid ejection surface.   The printing apparatus according to claim 1, wherein the plasma actuator is arranged side by side with the nozzle row.   The printing apparatus according to claim 1, wherein the plasma actuator is disposed on a support member of the inkjet head.   5. The printing apparatus according to claim 1, wherein the plasma actuator is disposed at a position farther than a distance between the liquid ejecting surface and the print medium.   The printing apparatus according to claim 1, wherein the plasma actuator is disposed on a surface that intersects the liquid ejecting surface.   The printing apparatus according to any one of claims 1 to 6, wherein an airflow generation region by the plasma actuator is a region longer than a length of the nozzle row.   The printing apparatus according to any one of claims 1 to 7, wherein the inkjet head is configured by arranging a plurality of unit inkjet heads in a staggered manner.   The printing apparatus according to claim 8, wherein the plasma actuator is disposed for each unit inkjet head.   The printing apparatus according to claim 1, wherein the plasma actuator includes a plurality of plasma actuators arranged side by side.   The controller drives the plasma actuator so that liquid droplets that do not reach the print medium generated by ejecting liquid from the nozzle row do not stay around the liquid ejecting surface. The printing apparatus according to any one of claims 1 to 10, wherein an air flow is generated.   The said control part generates airflow in the same direction as the conveyance direction of the said printing medium, or a reverse direction by drive-controlling the said plasma actuator, The Claim 1 characterized by the above-mentioned. The printing apparatus as described.   The printing according to any one of claims 1 to 12, wherein the control unit drives the plasma actuator to generate an air flow when liquid is not ejected from the nozzle row. apparatus.   13. The printing apparatus according to claim 1, wherein the control unit does not drive the plasma actuator when the liquid is ejected from the nozzle row for printing. 13. .   The printing apparatus according to any one of claims 1 to 12, wherein the control unit drives the plasma actuator to generate an air flow during a flushing operation by the inkjet head.   The printing apparatus according to claim 10, wherein the control unit drives the plasma actuator corresponding to the nozzle from which the liquid is ejected by individually controlling the plurality of plasma actuators.   The drive voltage generation unit for generating a drive voltage for driving the plasma actuator is further provided, and the drive voltage generation unit is mounted on the head unit. A printing apparatus according to claim 1.   The head unit includes a wiring for supplying an inkjet driving voltage for driving the inkjet head, and the driving voltage generation unit generates a voltage for driving the plasma actuator from the inkjet driving voltage. The printing apparatus according to claim 17.   The printing apparatus according to any one of claims 1 to 18, wherein the plasma actuator is configured to be detachable.   20. The filter according to claim 1, further comprising a filter that collects droplets that float without reaching the print medium downstream of an air flow generated by the plasma actuator, and the filter is detachable. A printing apparatus according to claim 1. Using a printing apparatus that performs printing by ejecting liquid onto a print medium transported by a print medium transport unit from a nozzle row that opens to a liquid ejecting surface of a line-shaped inkjet head,
A printing method, wherein a plasma actuator is driven to generate an air flow with respect to a platen gap of the printing apparatus. A line-like inkjet head comprising: a liquid ejecting surface disposed on a surface facing the print medium; and a nozzle array that opens to the liquid ejecting surface and ejects liquid onto the print medium;
With a plasma actuator,
The head unit, wherein the plasma actuator generates an air flow in a space in which the nozzle row ejects liquid.

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