Liquid discharge apparatus

Abstract

If the paper dust attracted to the plate-shaped member is left accumulated, the attracted paper dust may fall onto the sheet. However, there is no disclosure of a technique for removing the paper dust attracted to the plate-shaped member from the plate-shaped member, and there is room for improvement.SOLUTION: A transport belt that transports a medium in a transport direction by circulating, a charging section that charges the medium transported in the transport direction, an clinging member that is located downstream of the charging section in the transport direction, is provided to face the transport belt, and is charged to a polarity opposite to a polarity that the charging section imparts to the medium, an impact imparting section that performs an impact imparting operation of imparting an impact to the clinging member, and a suction section that air in the vicinity of the clinging member, the impact application section performs an impact application operation in a state in which the attachment member does not oppose the medium that is transported by the transport belt.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present disclosure relates to a liquid ejection device. [Background technology]

[0002] Patent Document 1 discloses an inkjet recording device in which a plate-like member is disposed upstream of the recording head in the paper transport direction. In the inkjet recording device described in Patent Document 1, in order to prevent paper dust from adhering to the recording head, paper dust adhering to the paper is adsorbed to the plate-like member by Coulomb force. This removes paper dust from the paper before the paper is transported to the recording head, thereby preventing paper dust from adhering to the recording head. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2016-129982 Summary of the Invention [Problem to be solved by the invention]

[0004] In the inkjet recording device described in Patent Document 1, if paper dust adsorbed to the plate-like member is left to accumulate, the adsorbed paper dust may fall onto the paper. However, there is no disclosure of a technique for removing paper dust adsorbed to the plate-like member from the plate-like member, and there is room for improvement. [Means for solving the problem]

[0005] The liquid ejection device comprises a conveying belt that rotates to transport a medium in a transport direction, a charging unit that charges the medium transported in the transport direction, an adsorption member that is located downstream of the charging unit in the transport direction and opposite the conveying belt, and is charged with a polarity opposite to the polarity imparted to the medium by the charging unit, an impact applying unit that performs an impact application operation to apply an impact to the adsorption member, a suction unit that sucks air near the adsorption member, and a liquid ejection unit that is located downstream of the adsorption member in the transport direction and ejects liquid onto the medium, and the impact applying unit performs the impact application operation while the adsorption member is not facing the medium transported by the conveying belt. [Brief explanation of the drawings]

[0006] [Figure 1] FIG. 1 is a cross-sectional view seen from the front, schematically illustrating the configuration of a liquid ejection device. [Figure 2A] FIG. 2 is an enlarged view showing the fixed position of the adsorption member and its surroundings in FIG. [Figure 2B] Cross-sectional view taken along line AA in FIG. 2A. [Figure 3A] 2 is an enlarged view showing the upper contact position of the attraction member and its surroundings in FIG. 1; [Figure 3B] Cross-sectional view taken along line BB in FIG. 3A. [Figure 4A] 2 is an enlarged view showing the contact position of the second displacement member and its surroundings in FIG. 1; [Figure 4B] Cross-sectional view taken along line CC in FIG. 4A. [Figure 5A] 2 is an enlarged view showing the lower contact position of the attraction member and its surroundings in FIG. 1; [Figure 5B] Cross-sectional view taken along line DD in FIG. 5A. [Figure 6] 10 is a flowchart showing removal control during a flushing operation. [Figure 7] 10 is a flowchart showing removal control for each job. [Figure 8] 10 is a flowchart showing removal control during a cleaning operation. [Figure 9] 10 is a flowchart showing removal control during manual execution. DETAILED DESCRIPTION OF THE INVENTION

[0007] In the embodiment described below, an inkjet printer that records an image or the like on paper M by ejecting liquid onto paper M will be exemplified as an example of the liquid ejection device 1, and will be described with reference to the drawings. Paper M is an example of a "medium." The medium may be paper, synthetic paper, film, or the like.

[0008] In the drawings shown below, the scale of each component is different from the actual scale in order to make each component large enough to be recognizable. Furthermore, in each drawing, the same components are given the same reference numerals, and redundant explanations are omitted. Furthermore, in each drawing, at least one of the X-axis, Y-axis, and Z-axis is illustrated as necessary as mutually orthogonal coordinate axes. The X-axis, Y-axis, and Z-axis are each indicated with an arrow. For each of the X-axis, Y-axis, and Z-axis, the direction of the arrow is the + direction, and the direction opposite to the arrow is the - direction.

[0009] The X axis is an axis parallel to the installation surface of the liquid ejection device 1 and corresponds to the width direction of the liquid ejection device 1. The +X direction parallel to the X axis is the direction in which the paper M is transported when liquid is ejected onto the paper M, and is also referred to as the transport direction. In FIG. 1, the +X direction is the direction from right to left when looking at the drawing. The -X direction parallel to the X axis is the direction opposite to the +X direction. In the liquid ejection device 1, the +X direction side is the left side, and the -X direction side is the right side. In the liquid ejection device 1, the transport direction in which the paper M is transported is also referred to as the downstream side, and the opposite direction is also referred to as the upstream side.

[0010] The Y axis is an axis parallel to the installation surface of the liquid ejection device 1, and corresponds to the depth direction of the liquid ejection device 1 and the width direction of the paper M. The +Y direction parallel to the Y axis is the direction from the front to the back of the liquid ejection device 1. The -Y direction parallel to the Y axis is the direction opposite to the +Y direction. In the liquid ejection device 1, the +Y direction side is the back side, and the -Y direction side is the front side.

[0011] The Z axis is an axis perpendicular to the installation surface of the liquid ejection device 1, and corresponds to the height direction of the liquid ejection device 1. When the installation surface of the liquid ejection device 1 is horizontal, the Z axis is an axis along the vertical direction. The +Z direction parallel to the Z axis is the direction from below to above the liquid ejection device 1. The -Z direction parallel to the Z axis is the direction opposite to the +Z direction. In the liquid ejection device 1, the +Z direction side is the upper side, and the -Z direction side is the lower side. The part located on the upper side is also referred to as the upper part, and the surface facing upward is also referred to as the upper surface. The part located on the lower side is also referred to as the lower part, and the surface facing downward is also referred to as the lower surface.

[0012] In the following description, the direction parallel to the X-axis will also be referred to as the X-axis direction, the direction parallel to the Y-axis will also be referred to as the Y-axis direction, and the direction parallel to the Z-axis will also be referred to as the Z-axis direction. In other words, the X-axis direction includes both the +X direction and the -X direction, the Y-axis direction includes both the +Y direction and the -Y direction, and the Z-axis direction includes both the +Z direction and the -Z direction.

[0013] The liquid ejection device 1 will be described with reference to Fig. 1. As shown in Fig. 1, the liquid ejection device 1 includes a control unit 2, a feeding unit 20, a transport unit 30, a suction unit 40, a charging unit 50, an adsorption unit 60, a static elimination unit 70, a liquid ejection unit 80, and an ejection unit 90 inside a housing 10. An ejection port 11 for ejecting paper M is provided at the left end of the housing 10. Paper M sent from the ejection unit 90 is ejected from the ejection port 11 to the outside of the liquid ejection device 1.

[0014] The control unit 2 includes an instruction receiving unit 2A. Although not shown, the control unit 2 also includes, for example, a processor, a memory unit, an input / output interface for inputting and outputting signals from and to the outside, and a display unit. The control unit 2 is configured by a combination of multiple circuits. The instruction receiving unit 2A is configured by, for example, operation keys. The instruction receiving unit 2A may also be a touch panel integrated with the display unit. The instruction receiving unit 2A receives instructions from a user. The control unit 2 performs various functions by having the processor execute programs stored in the memory unit. The control unit 2 controls various operations performed by the feeding unit 20, the conveying unit 30, the suction unit 40, the charging unit 50, the adsorption unit 60, the static elimination unit 70, the liquid discharge unit 80, and the discharge unit 90. The control unit 2 may also be configured by a computer.

[0015] The feeding section 20 includes a feeding cassette 21, a pickup roller 22, a feeding guide 23, a feeding roller pair 24, a feeding path 25, and a registration roller pair 26. The feeding cassette 21 is disposed at the bottom inside the housing 10 and is detachable from the housing 10. The feeding cassette 21 stores a stack of paper sheets M.

[0016] The pickup roller 22 is disposed above the feed cassette 21. The sheets M stored in the feed cassette 21 are pressed against the pickup roller 22 by the feed cassette 21. As the pickup roller 22 rotates, the sheets M pressed against the pickup roller 22 are picked up one by one and sent to the feed guide 23. The feed guide 23 guides the sheets M picked up by the pickup roller 22 to the pair of feed rollers 24.

[0017] The pair of feed rollers 24 is made up of a drive roller and a driven roller, and sandwiches the paper M between the drive roller and the driven roller and sends it to the feed path 25. The paper M sent into the feed path 25 is sent towards the pair of registration rollers 26. The leading edge of the paper M sent to the pair of registration rollers 26 abuts against the pair of registration rollers 26, and a flexure is formed in the paper M between the pair of registration rollers 26 and the pair of feed rollers 24. As a result, the leading edge of the paper M follows the pair of registration rollers 26, and skew is corrected.

[0018] The pair of registration rollers 26 is composed of a drive roller and a driven roller, and sandwiches the paper M between the drive roller and the driven roller to send it toward the conveying section 30. Note that the pair of registration rollers 26 temporarily stops the conveyance of the paper M in order to synchronize the timing of conveying the paper M with the timing of discharging liquid onto the paper M, and then sends the paper M toward the conveying section 30 in accordance with the synchronized timing.

[0019] The conveying section 30 includes a conveying belt 31, a conveying drive roller 32, a tension roller 33, a guide roller , a belt peripheral speed detection roller 35, and a pressure roller .

[0020] The conveyor belt 31 is an endless belt that rotates to convey the paper M in the conveyance direction. The conveyor belt 31 is stretched by a conveyance drive roller 32, a tension roller 33, a guide roller 34, and a belt peripheral speed detection roller 35. As the conveyor drive roller 32 drives counterclockwise as viewed in the drawing, the conveyor belt 31 conveys the paper M from upstream to downstream in the conveyance direction.

[0021] The conveying surface 31A of the conveying belt 31 is maintained flat by the conveying drive roller 32, the belt peripheral speed detection roller 35, and a platen 41 (described later). The conveying surface 31A faces the +Z direction and faces the charging unit 50, the attracting unit 60, the static eliminator 70, and the liquid ejecting unit 80. The conveying belt 31 has a plurality of through holes (not shown). The through holes formed in the conveying belt 31 penetrate the conveying surface 31A and the opposite surface of the conveying surface 31A.

[0022] The transport drive roller 32 is disposed downstream in the transport direction relative to the suction unit 40. The transport drive roller 32 is driven to rotate by a motor (not shown). The transport surface 31A of the transport belt 31 is pulled in the downstream direction by the transport drive roller 32 disposed downstream in the transport direction, so that the transport surface 31A does not flex. This also keeps the transport surface 31A flat.

[0023] The tension roller 33 applies tension to the conveyor belt 31 to prevent the conveyor belt 31 from bending. The guide roller 34 is disposed below the suction unit 40, and forms a space inside the conveyor belt 31 in which the suction unit 40 can be disposed.

[0024] The belt peripheral speed detection roller 35 is disposed upstream of the suction unit 40 in the conveying direction, and is a driven roller that rotates in accordance with the conveyance of the conveyor belt 31. The belt peripheral speed detection roller 35 includes a rotary encoder (not shown), and rotates together with the rotary encoder. The control unit 2 controls the peripheral speed of the conveyor belt 31, i.e., the conveyance speed of the paper M, by measuring the rotation speed of the rotary encoder.

[0025] The pressure roller 36 is in contact with the conveying surface 31A of the conveyor belt 31, and presses the sheet M sent from the pair of registration rollers 26 against the conveying surface 31A. The pressure roller 36 rotates as the conveyor belt 31 rotates.

[0026] The suction unit 40 applies negative pressure to the paper M via the conveyor belt 31, thereby sucking the paper M onto the conveyor belt 31. The suction unit 40 also sucks air near the adsorption member 61. The suction unit 40 includes a platen 41, an air flow guide 42, a negative pressure generating unit 43, and an exhaust port 44.

[0027] The platen 41 supports the conveyor belt 31 so as to be able to face the charging unit 50, the adsorption unit 60, the static elimination unit 70, and the liquid ejection unit 80. The platen 41 also supports the paper M via the conveyor belt 31. The platen 41 has a plurality of grooves (not shown). The grooves are oval grooves extending along the conveyance direction. Holes are formed in the grooves that penetrate from the conveyor belt 31 side toward the air flow guide 42 side. The grooves are formed in a row in the conveyance direction. The grooves are also formed in parallel in the Y-axis direction of the platen 41.

[0028] The platen 41 is made of, for example, a metal material. Specifically, the platen 41 can be made of a plate that has been pressed from aluminum, stainless steel, or the like. The platen 41 is connected to a ground potential. Note that in this embodiment, the suction unit 40 is described as including the platen 41, but as described above, since the platen 41 supports the conveyor belt 31, the conveyor unit 30 may also be described as including the platen 41.

[0029] The air flow guide 42 is, for example, a cylindrical member with openings on the top and bottom. The top surfaces of the side walls that make up the air flow guide 42 are fixed to the platen 41. The negative pressure generating unit 43 is disposed below the air flow guide 42. Below the negative pressure generating unit 43, an exhaust port 44 is disposed, which exhausts the air sucked by the negative pressure generating unit 43 to the outside of the suction unit 40 via a filter (not shown). The negative pressure generating unit 43 may be any device that generates negative pressure within the air flow guide 42, and may be, for example, a fan or a vacuum pump.

[0030] When the negative pressure generating unit 43 is driven, a negative pressure of, for example, approximately 500 Pa is generated inside the air flow guide 42, and this negative pressure causes the paper M to be sucked onto the conveyor belt 31. The suction force caused by the negative pressure that sucks the paper M onto the conveyor belt 31 is referred to as a first suction force F1. The suction force of the negative pressure generating unit 43 can be changed, for example, between the first suction force F1 and a second suction force greater than the first suction force F1, by switching the driving force of the negative pressure generating unit 43.

[0031] At least some of the grooves formed in the platen 41 and the through holes formed in the conveyor belt 31 are arranged so that negative pressure can pass through each other at any position in the conveyance direction while the conveyor belt 31 is rotating. This allows the suction unit 40 to suck the sheet M onto the conveyor belt 31, from the leading edge of the sheet M in the conveyance direction to the trailing edge of the sheet M in the conveyance direction.

[0032] The charging unit 50 includes a charging electrode 51 and a first power source 52. The charging electrode 51 is a needle-shaped electrode, but is not limited to this. The charging electrode 51 may also be brush-shaped. The first power source 52 is connected to the charging electrode 51 and applies a charging voltage to the paper M via the charging electrode 51. The charging electrode 51 charges the paper M, paper dust D adhering to the paper M, or paper dust D generated from the paper M to a potential with the same polarity as the charging polarity of the liquid discharger 80. Specifically, when the liquid discharger 80 is negatively charged, the first power source 52 applies a voltage of, for example, −2.2 kV to the charging electrode 51. In this case, the paper M and paper dust D are charged to, for example, −70 V.

[0033] The charging electrode 51 is disposed between the tension roller 33, which is disposed upstream in the transport direction relative to the charging electrode 51, and the adsorption unit 60, which is disposed downstream in the transport direction. The distance between the charging electrode 51 and the upper surface of the paper M transported below the charging electrode 51 is a distance that allows the paper M to be charged without being hindered from being transported by the transport belt 31.

[0034] The suction unit 60 includes an suction member 61, a second power source 62, a first displacement member 64, and an upper contact member 67. The suction unit 60 also includes a second displacement member 65 and a lower contact member 68 shown in FIG. 2A. The first displacement member 64, the second displacement member 65, the upper contact member 67, and the lower contact member 68 are an example of an "impact applying unit." The suction unit 60 uses Coulomb force to suction paper dust D adhering to the sheet M or paper dust D generated from the sheet M from the sheet M to the suction member 61. The suction unit 60 can also remove the paper dust D that has been adsorbed to the suction member 61 from the suction member 61 by the impact applying unit.

[0035] The attraction member 61 is a plate-like member that is rectangular in plan view when viewed from above, and faces the entire width of the conveyor belt 31 along the Y-axis direction. The second power source 62 is connected to the attraction member 61 and applies a voltage to the attraction member 61 that has a polarity opposite to that of the first power source 52. In other words, the attraction member 61 is charged with a polarity opposite to that applied to the paper M by the charging unit 50. Specifically, when the liquid discharge unit 80 is charged to a negative potential, the second power source 62 applies a voltage of, for example, +3.0 kV to the attraction member 61. As a result, the attraction member 61 is charged to a positive potential.

[0036] The adsorption member 61 is located downstream of the charging unit 50 in the conveyance direction and is provided facing the conveyor belt 31. The distance between the adsorption member 61 and the upper surface of the sheet M conveyed below the adsorption member 61 is a distance that allows the sheet M to be conveyed by the conveyor belt 31 without being hindered and allows paper dust D to be adsorbed from the sheet M by Coulomb force. The impact applying unit performs an impact applying operation to the adsorption member 61, thereby removing the paper dust D adsorbed to the adsorption member 61 from the adsorption member 61. Details of the adsorption unit 60 will be described later.

[0037] The static elimination unit 70 includes a static elimination electrode 71 and a third power source 72. The static elimination electrode 71 is a needle-shaped electrode, but is not limited to this. The static elimination electrode 71 may also be brush-shaped. The third power source 72 is connected to the static elimination electrode 71 and applies a voltage of opposite polarity to that of the first power source 52 to the paper M via the static elimination electrode 71. Specifically, when the liquid ejection unit 80 is negatively charged, the third power source 72 applies a voltage of, for example, +3.0 kV to the static elimination electrode 71. This causes static elimination of the paper M. In other words, the charge on the paper M, which is charging the paper M to -70 V, moves to the platen 41, which is connected to ground potential.

[0038] The neutralization electrode 71 is disposed between the suction unit 60, which is disposed upstream in the conveyance direction relative to the neutralization electrode 71, and the liquid discharge unit 80, which is disposed downstream in the conveyance direction relative to the neutralization electrode 71. The distance between the neutralization electrode 71 and the upper surface of the paper M conveyed below the neutralization electrode 71 is a distance that allows the paper M to be conveyed by the conveyor belt 31 without being hindered, and allows neutralization of the paper M.

[0039] In the above, a case has been described in which the third power source 72 neutralizes the electricity in the paper M, but more preferably, the third power source 72 sets the potential of the paper M to a potential similar to that of the liquid discharger 80. When the potential of the paper M is similar to that of the liquid discharger 80, the adhesion of paper dust D to the liquid discharger 80 can be further suppressed by Coulomb force.

[0040] The liquid ejection unit 80 is charged to a negative potential when a nozzle forming surface (not shown) formed on the liquid ejection unit 80 is coated with fluorine. In this case, the third power source 72 applies a voltage of, for example, +2.5 kV to the neutralization electrode 71 so that the paper M has a potential similar to the potential of the liquid ejection unit 80, for example, −40 V.

[0041] The liquid ejection unit 80 is an inkjet head located downstream of the adsorption member 61 in the transport direction, and ejects liquid onto the transported paper M to record an image or the like. The liquid ejection unit 80 has a plurality of nozzles formed therein that eject the liquid. The plurality of nozzles are formed on a surface that faces the transport surface 31A of the transport belt 31. The liquid is, for example, ink, pre-treatment liquid, post-treatment liquid, cleaning liquid, or water. The liquid ejection unit 80 is also a line head that can eject a single type of liquid or multiple types of liquid simultaneously across the entire width of the paper M.

[0042] The maintenance unit 81 performs maintenance operations to prevent or resolve ejection problems caused by clogging of the nozzles of the liquid ejection unit 80 or adhesion of paper dust D. The maintenance operations include capping, flushing, nozzle suction, and wiping. The maintenance unit 81 includes a cap member, a liquid suction member, a wiper member, a liquid receiving member, and the like, all of which are not shown.

[0043] When liquid is being ejected from the liquid ejection unit 80 onto the paper M, the maintenance unit 81 stands by in a spaced position away from the liquid ejection unit 80 so as not to interrupt the ejection of liquid onto the paper M. Furthermore, when performing maintenance on the liquid ejection unit 80, the maintenance unit 81 moves to a maintenance position that covers the nozzles of the liquid ejection unit 80. Switching between the spaced position and the maintenance position is performed by driving a motor (not shown).

[0044] The cap member seals the nozzles by covering the nozzle formation surface of the liquid ejection unit 80. The capping operation refers to the operation in which the cap member comes into contact with the nozzle formation surface of the liquid ejection unit 80 so as to surround the nozzles. When the liquid ejection unit 80 is not ejecting liquid, the capping operation suppresses the thickening of the liquid inside the nozzles, thereby preventing ejection defects. The capping operation is included in the operations that are performed in conjunction with the flushing operation, the nozzle suction operation, and the wiping operation.

[0045] The liquid suction member applies negative pressure to the nozzle, thereby sucking the liquid from the nozzle and paper dust D adhering to the nozzle together with the liquid. The nozzle suction operation refers to the operation of the liquid suction member applying suction force to the nozzle to forcibly suck the liquid from the nozzle.

[0046] The wiper member wipes away paper dust D adhering to the nozzles by rubbing against the nozzle formation surface of the liquid ejection unit 80. For example, a rubber wiper or a cloth wiper is used as the wiper member. The wiping operation refers to the operation of wiping the nozzle formation surface with the wiper member. The wiping operation removes liquid and dirt such as paper dust D adhering to the nozzle formation surface of the liquid ejection unit 80. The nozzle suction operation and wiping operation are examples of a "cleaning operation."

[0047] The liquid receiving member receives the liquid ejected from the nozzles when a flushing operation is performed. The flushing operation is an ejection operation for ejecting liquid that is not related to recording an image or the like from the nozzles. The flushing operation ejects thickened ink, air bubbles, or paper dust D that can cause ejection problems from the nozzles, thereby preventing nozzle clogging.

[0048] The discharge section 90 includes a discharge guide 91, a discharge roller pair 92, and a discharge tray 93. The discharge guide 91 guides the paper sheet M discharged from the conveyor belt 31 to the discharge roller pair 92. The discharge roller pair 92 transports the paper sheet M that has passed through the discharge guide 91 in the direction of the discharge opening 11. The paper sheet M transported by the discharge roller pair 92 is discharged to the discharge tray 93 via the discharge opening 11. The discharge tray 93 places the paper sheet M discharged from the discharge opening 11 on it. The discharge tray 93 is fixed to the housing 10 so as to protrude outward from the discharge opening 11.

[0049] Next, the operation of the liquid ejection device 1 will be described. When the control unit 2 receives a job command to record an image or the like, it takes out the paper M from the feeding unit 20. The taken-out paper M is transported to the conveying unit 30. The paper M transported to the conveying unit 30 is attracted to the conveying belt 31 by the first suction force F1 of the suction unit 40. The paper M is transported below the charging unit 50. The paper M and paper dust D are charged to a negative potential by the charging unit 50.

[0050] The paper sheet M and paper dust D are transported below the adsorption unit 60. The paper dust D, which is negatively charged, is attracted to the adsorption unit 60, which is positively charged, by Coulomb force. The paper sheet M, which is negatively charged, is transported below the charge removal unit 70. The paper sheet M transported to the charge removal unit 70 is neutralized by the charge removal unit 70. In other words, the paper sheet M transported to the charge removal unit 70 is rendered uncharged by the charge removal unit 70.

[0051] The paper sheet M that has been neutralized by the neutralization unit 70 is transported to the liquid discharge unit 80, where an image or the like is recorded using liquid discharged from the liquid discharge unit 80. Note that the paper sheet M that has been transported to the liquid discharge unit 80 has paper dust D adsorbed by the adsorption unit 60, which prevents the paper dust D from adhering to the liquid discharge unit 80. Note that even if the paper dust D is transported below the liquid discharge unit 80, because the paper dust D has been neutralized, Coulomb force prevents the paper dust D from adhering to the liquid discharge unit 80. Then, the paper sheet M on which an image or the like has been recorded by the liquid discharge unit 80 is discharged to the discharge tray 93 of the discharge unit 90.

[0052] In this way, the series of operations from when the control unit 2 receives a job command until the paper M on which an image or the like has been recorded is discharged from the discharge unit 90 is an example of a "job." A job includes a job for one sheet of paper M, or a job for a set of sheets of paper M consisting of multiple sheets. In other words, a job refers to a series of operations for recording an image or the like on one sheet of paper M, and includes, for example, the operation of transporting the paper M after recording an image or text. There is no limit to the number of sheets of paper M that make up one job. In other words, a job also means executing a process for ejecting liquid onto the paper M.

[0053] Next, the adsorption unit 60 will be described in detail with reference to Figures 2A to 5B. Note that Figures 3A to 5B show a state in which the sheet M transported by the conveyor belt 31 does not face the adsorption unit 60. Furthermore, the impact applying unit performs an impact applying operation to the adsorption member 61 in a state in which the adsorption member 61 does not face the sheet M transported by the conveyor belt 31.

[0054] 2A and 2B show a state in which the adsorption member 61 is located at a fixed position P1. The fixed position P1 is a position where the adsorption member 61 adsorbs paper powder D. As shown in FIGS. 2A and 2B, the adsorption unit 60 includes an adsorption unit housing 61A, a holding member 63, and a moving unit 66, in addition to the adsorption member 61, first displacement member 64, second displacement member 65, upper contact member 67, and lower contact member 68 described above.

[0055] The adsorption unit housing 61A is provided on the upper surface of the adsorption member 61 and holds the adsorption member 61. The holding member 63 is connected to the upper surface of the adsorption unit housing 61A and to the housing 10. The holding member 63 holds the adsorption member 61 in a displaceable manner so that the distance between the adsorption member 61 and the conveyor belt 31 is a predetermined distance. In this embodiment, the holding member 63 is a plurality of tension springs, and the adsorption member 61 is always biased upward by the plurality of tension springs. In this embodiment, four tension springs are provided so that the adsorption member 61 and the conveyor surface 31A face each other in parallel.

[0056] In this embodiment, the number of tension springs is four, but this is not limited to this. The number of tension springs does not have to be four as long as the attraction member 61 and the conveying surface 31A can be made to face each other in parallel. Also, the holding member 63 is made up of a plurality of tension springs, but this is not limited to this. The holding member 63 may be an elastic body other than a spring.

[0057] A plurality of first displacement members 64 are provided inside the attraction unit housing 61A. Each first displacement member 64 is provided with a first displacement member rotation shaft 64C. The first displacement member 64 is a member that displaces the position of the attraction member 61 in the Z-axis direction to bring it into contact with the upper contact member 67, and is an example of a "displacement member." In this embodiment, two first displacement members 64 are provided. The first displacement members 64 are plate cams, and are provided adjacent to each other in the X-axis direction with their first displacement member rotation shafts 64C aligned along the Y-axis. The first displacement members 64 rotate to displace the attraction member 61 in the up and down direction.

[0058] The first displacement member 64 is formed with a first displacement member low portion 64A, which has a short distance from the first displacement member rotation shaft 64C to the outer periphery of the first displacement member 64, and a first displacement member high portion 64B, which has a longer distance from the first displacement member rotation shaft 64C to the outer periphery of the first displacement member 64 than the first displacement member low portion 64A. When the first displacement member high portion 64B is positioned facing vertically downward, the first displacement member 64 abuts against the upper surface of the attraction member 61. When the first displacement member low portion 64A is positioned facing vertically downward, the attraction member 61 is displaced upward by the biasing force of the holding member 63.

[0059] A shaft window 61B is formed on a side surface of the attraction unit housing 61A that intersects with the Y axis. The first displacement member rotation shaft 64C extends in the Y axis direction through the shaft window 61B and is rotatably supported by the housing 10. The shaft window 61B is formed long in the Z axis direction, allowing the attraction member 61 to be displaced in the Z axis direction. The first displacement member rotation shaft 64C is rotated counterclockwise as viewed in FIG. 2A by a first motor 64D.

[0060] The first displacement member lower portion 64A and the first displacement member higher portion 64B formed on the two first displacement members 64 are rotationally driven by a first displacement member rotation shaft 64C that interlocks with each other. That is, the first displacement member lower portion 64A and the first displacement member higher portion 64B formed on the two first displacement members 64 are rotationally driven so that their positional changes are in phase with each other.

[0061] When the first displacement member 64 rotates and the first displacement member high portion 64B comes into contact with the upper surface of the attraction member 61, the attraction member 61 is positioned at the fixed position P1. In other words, when the attraction member 61 is at the fixed position P1, the upper surface of the attraction member 61, which is urged upward by the holding member 63, comes into contact with the first displacement member high portion 64B.

[0062] The first displacement member high portions 64B of two first displacement members 64 arranged adjacent to each other in the X-axis direction come into contact with the upper surfaces of the attraction members 61 in the same phase, so that the attraction members 61 do not swing in the rotational direction about the first displacement member rotation shafts 64C. In this embodiment, there are two first displacement members 64, but this is not limited to this. As long as the attraction members 61 do not swing in the rotational direction about the first displacement member rotation shafts 64C, there may be one first displacement member 64, or three or more first displacement members 64.

[0063] A plurality of second displacement members 65 are provided above the attraction member 61. The second displacement members 65 are members that displace the position of the attraction member 61 in the Z-axis direction to bring it into contact with the lower contact member 68, and are an example of a "displacement member." One second displacement member 65 is provided at each end of the attraction member 61 in the width direction along the Y-axis. The second displacement member 65 is shaft-shaped, and a second displacement member tip 65A is formed at one end. The second displacement member 65 is approximately hammer-shaped, with its center of gravity at the second displacement member tip 65A. A second displacement member rotation shaft 65B is provided at the other end of the second displacement member 65. The second displacement member 65 is rotatable around the second displacement member rotation shaft 65B.

[0064] The second displacement member 65 is movable in the conveyance direction by a moving unit 66. The second displacement member rotation shaft 65B is rotationally driven by a second motor 65C. The second motor 65C switches the rotation angle and rotation direction to displace the position of the second displacement member tip 65A among a standby position PS1, an abutment position PS2, and a contact position PS3. The standby position PS1 is a position where the second displacement member tip 65A does not abut the upper surface of the attraction member 61. The abutment position PS2 is a position where the second displacement member tip 65A abuts the upper surface of the attraction member 61 located at the home position P1. The contact position PS3 is a position where the second displacement member tip 65A abuts the upper surface of the attraction member 61 and brings the attraction member 61 into contact with the lower contact member upper portion 68A located above the lower contact member 68.

[0065] The moving unit 66 moves the second displacement member 65 along the conveying direction. The moving unit 66 is, for example, a ball screw. The ball screw is connected to the third motor 66A and converts the rotational motion of the third motor 66A into linear motion along the X-axis. The second displacement member 65 can be moved by the moving unit 66 along the conveying direction from the upstream side to the downstream side or from the downstream side to the upstream side of the upper surface of the attraction member 61.

[0066] This allows the second displacement member 65 to come into contact with the upper surface of the attraction member 61 at an upstream position PS4, which is on the upstream side of the upper surface of the attraction member 61. Furthermore, the second displacement member 65 can come into contact with the upper surface of the attraction member 61 at a downstream position PS5, which is on the downstream side of the upper surface of the attraction member 61. The position on the upper surface of the attraction member 61 with which the tip end 65A of the second displacement member comes into contact is the outer edge of the upper surface of the attraction member 61, which is located further outward in the Y-axis direction than the upper contact member 67.

[0067] Above the upper surface of the attraction member 61, a plurality of upper contact members 67 are provided, which can come into contact with the upper part of the attraction member 61 as the first displacement member 64 is displaced. The upper contact members 67 are an example of a "contact member" and a "first contact member." In this embodiment, four upper contact members 67 are provided, corresponding to the corners of the attraction member 61 in a plan view seen from above. The attraction member 61, which is biased upward by the holding member 63, moves upward as the first displacement member 64 rotates, and comes into contact with a lower upper contact member 67A of the upper contact member 67. The position of the attraction member 61 when the upper part of the attraction member 61 comes into contact with the lower upper contact member 67A is the upper contact position P2.

[0068] A plurality of lower contact members 68 are provided below the lower surface of the attraction member 61, and are capable of coming into contact with the lower part of the attraction member 61 as the second displacement member 65 is displaced. The lower contact members 68 are an example of a "contact member" and a "second contact member." In this embodiment, four lower contact members 68 are provided corresponding to the corners of the attraction member 61. The attraction member 61, which is positioned at home position P1, comes into contact with an upper part 68A of a lower contact member 68 positioned further below home position P1 as the second displacement member 65 rotates. The position of the attraction member 61 when the lower part of the attraction member 61 comes into contact with the upper part 68A of the lower contact member is lower contact position P3.

[0069] 3A and 3B, a manner in which paper dust D is removed from the attracting member 61 at the upper contact position P2 will be described. When the first displacement member lower portion 64A rotated by the first motor 64D faces the attracting member 61, the position of the first displacement member lower portion 64A facing the attracting member 61 is higher than the upper contact member lower portion 67A. Therefore, when the first displacement member lower portion 64A faces the attracting member 61, the upper portion of the attracting member 61 moves upward due to the biasing force of the holding member 63 and comes into contact with the upper contact member 67.

[0070] When the adsorption member 61 and the upper contact member 67 come into contact with each other, an impact is applied to the adsorption member 61. This impact causes the paper powder D adsorbed to the adsorption member 61 to be removed from the adsorption member 61. Note that the action of applying an impact to the adsorption member 61 by bringing the adsorption member 61 into contact with the upper contact member 67 at the upper contact position P2 is an example of a "repelling action."

[0071] 4A and 4B, a manner in which paper dust D is removed from the adsorption member 61 even at the fixed position P1 will be described. When the adsorption member 61 is located at the fixed position P1, the second motor 65C rotates the second displacement member 65 to bring the tip 65A of the second displacement member into contact with the upper surface of the adsorption member 61. The tip 65A of the second displacement member rotates to a contact position PS2 where it contacts the upper surface of the adsorption member 61, thereby applying an impact to the adsorption member 61. The paper dust D adsorbed to the adsorption member 61 is removed from the adsorption member 61 by this impact.

[0072] Moreover, the second displacement member 65 can be moved along the conveyance direction by the moving portion 66. This allows the second displacement member 65 to come into contact with the upper surface of the attraction member 61 at an upstream position PS4 and a downstream position PS5 on the upper surface of the attraction member 61.

[0073] An impact is applied to the adsorption member 61 by contacting the upper surface of the adsorption member 61 with the second displacement member 65 at different positions, the upstream position PS4 and the downstream position PS5. This impact removes paper powder D that has been adsorbed at different positions along the conveyance direction of the adsorption member 61 from the adsorption member 61. Note that the action of applying an impact to the adsorption member 61 by bringing either the upstream side or the downstream side of the upper surface of the adsorption member 61 in the conveyance direction into contact with the tip end 65A of the second displacement member at the fixed position P1 is an example of a "first hitting action."

[0074] 5A and 5B, a description will be given of how paper dust D is removed from the attracting member 61 at the lower contact position P3. After the second displacement member tip 65A contacts the upper surface of the attracting member 61, the second motor 65C continues to rotate the second displacement member 65. The second displacement member tip 65A rotates to the contact position PS3, thereby pressing the attracting member 61 down to the lower contact position P3, which is located further below the home position P1. As a result, the lower part of the attracting member 61 comes into contact with the lower contact member upper part 68A of the lower contact member 68.

[0075] When the adsorption member 61 comes into contact with the lower contact member 68, an impact is applied to the adsorption member 61. This impact causes the paper powder D adsorbed to the adsorption member 61 to be removed from the adsorption member 61. Note that the action of applying an impact to the adsorption member 61 by bringing the adsorption member 61 into contact with the lower contact member 68 at the lower contact position P3 is an example of a "second hitting action."

[0076] In this embodiment, a "flicking action," a "first tapping action," and a "second tapping action" can be performed as actions for applying an impact to the adsorption member 61. Furthermore, different impacts can be applied to the adsorption member 61 by the different actions of the "first tapping action" and the "second tapping action," so that the paper dust D can be removed more precisely. The action of adding the "second tapping action" to the "first tapping action" is an example of a "tapping action."

[0077] Next, the removal control in the adsorption unit 60 will be described with reference to Fig. 6 to Fig. 9. The removal control refers to control for removing paper dust D from the adsorption member 61 by an impact application operation in which the impact application unit applies an impact to the adsorption member 61 while the adsorption member 61 is not facing the paper sheet M being transported on the transport belt 31.

[0078] Fig. 6 shows removal control during a flushing operation among the maintenance operations, Fig. 7 shows removal control for each job, Fig. 8 shows removal control during a cleaning operation among the maintenance operations, and Fig. 9 shows removal control during manual execution. Manual execution means that the instruction receiving unit 2A receives an instruction to execute an impact application operation instructed by the user, and the control unit 2 executes the instruction to execute the impact application operation received by the instruction receiving unit 2A. Note that subsequent control is controlled by the control unit 2.

[0079] 6, in the case of removal control during the flushing operation, first, in step S10, the control unit 2 executes a flicking operation once. The impact caused by the flicking operation removes the paper powder D adsorbed to the adsorption member 61 from the adsorption member 61. Then, in step S11, the control unit 2 executes a tapping operation once at the upstream position PS4 or the downstream position PS5. This further removes the paper powder D adsorbed to the adsorption member 61 from the adsorption member 61. The paper powder D removed from the adsorption member 61 is collected in the suction unit 40 by the suction force of the negative pressure generating unit 43.

[0080] The flushing operation is often performed during a job. To avoid a decrease in job throughput, the flushing operation must be performed in a short time. In the removal control during the flushing operation, priority is given to preventing a decrease in job throughput over the amount of paper dust D removed from the adsorption member 61. Therefore, while executing steps S10 and S11, the control unit 2 maintains the suction force of the negative pressure generator 43 at the same first suction force F1 as during the job, and keeps the second power source 62 ON, as during the job. This allows the control unit 2 to reduce the switching time required for changing the control of the negative pressure generator 43 and the second power source 62.

[0081] 7, in the case of job-by-job removal control, first, in step S20, the control unit 2 changes the suction force of the negative pressure generating unit 43 to a second suction force greater than the first suction force F1 by switching the driving force of the negative pressure generating unit 43. In step S21, the control unit 2 turns off the second power supply 62.

[0082] Note that "per job" includes at least one of before the start of a job and after the end of a job. Before the start of a job or after the end of a job, the permissible execution time for the impact application operation can be secured to be longer than during the flushing operation. In the removal control per job, more of the paper dust D adsorbed to the adsorption member 61 is removed by changing the control of the negative pressure generating unit 43 and the second power source 62 within a range that does not significantly reduce the throughput of the job.

[0083] In step S22, the control unit 2 determines at least one of whether the width of the paper M being transported is greater than a predetermined width, and whether the transport speed of the paper M being transported is greater than a predetermined transport speed. In other words, if the paper M is a wide medium or whether the paper M is being transported at high speed, that is, if the answer is "YES" in step S22, the control unit 2 proceeds to step S23. On the other hand, if the answer is neither of the above, that is, if the answer is "NO to all" in step S22, the control unit 2 proceeds to step S27.

[0084] Next, in step S23, the control unit 2 executes two flicking operations. The impact caused by the flicking operations removes the paper powder D adsorbed to the adsorption member 61 from the adsorption member 61. Furthermore, in step S24, the control unit 2 executes one set of tapping operations twice. This further removes the paper powder D adsorbed to the adsorption member 61 from the adsorption member 61. One set of tapping operations refers to a series of operations in which the second displacement member tip 65A is brought into contact with the upper surface of the adsorption member 61 once at the upstream position PS4 and once at the downstream position PS5. The paper powder D removed from the adsorption member 61 is collected in the suction unit 40 by the suction force generated by the negative pressure generator 43 in step S20.

[0085] In step S25, the control unit 2 changes the driving force of the negative pressure generating unit 43, thereby changing the suction force of the negative pressure generating unit 43 back to the first suction force F1 from the second suction force. In step S26, the control unit 2 turns the second power supply 62 back on. Steps S25 and S26 are steps for preparing for the next job.

[0086] If the answer is "NO to all" in step S22, the control unit 2 executes the flicking operation twice in step S27. The impact caused by the flicking operation removes the paper powder D adsorbed to the adsorption member 61 from the adsorption member 61. Furthermore, in step S28, the control unit 2 executes the tapping operation twice at the upstream position PS4 or the downstream position PS5. This further removes the paper powder D adsorbed to the adsorption member 61 from the adsorption member 61. The paper powder D removed from the adsorption member 61 is collected in the suction unit 40 by the suction force generated by the negative pressure generator 43 in step S20. Note that the removal control for each job may be performed before the start of a job, which is a process for discharging liquid onto the paper M, or after the job is completed, or may be performed both before the start of the job and after the job is completed. After step S28 is completed, the control unit 2 proceeds to step S25 and step S26.

[0087] In this way, with job-specific removal control, the permissible execution time can be secured longer than with flushing operations, so the number of flicks and taps is increased. This allows more paper dust D adsorbed to the adsorption member 61 to be removed. Furthermore, when the control unit 2 determines that the medium is a wide medium or that the medium is being transported at high speed, the amount of paper dust D adsorbed to the adsorption member 61 per unit time increases. Even in this case, the number of tapping operations is increased, so the paper dust D adsorbed to the adsorption member 61 is removed from the adsorption member 61.

[0088] As shown in FIG. 8, in the case of removal control during cleaning operation, first, in step S30, the control unit 2 changes the suction force of the negative pressure generator 43 to a second suction force that is greater than the first suction force F1 by switching the driving force of the negative pressure generator 43. In step S31, the control unit 2 turns off the second power source 62. Note that during cleaning operation, a longer permissible execution time, which is the time during which the impact application operation can be performed, can be secured than in removal control for each job. In removal control during cleaning operation, by changing the control of the negative pressure generator 43 and the second power source 62 within a range that does not significantly reduce job throughput, more paper powder D adsorbed to the adsorption member 61 is removed.

[0089] In step S32, the control unit 2 determines at least one of whether the width of the paper M being transported is greater than a predetermined width, and whether the transport speed of the paper M being transported is greater than a predetermined transport speed. In other words, if the paper M is a wide medium or whether the paper M is being transported at high speed, that is, if the answer is "YES" in step S32, the control unit 2 proceeds to step S33. On the other hand, if the answer is neither in step S32, that is, if the answer is "NO to all" in step S32, the control unit 2 proceeds to step S37.

[0090] Next, in step S33, the control unit 2 executes the flicking action three times. The impact caused by the flicking action removes the paper powder D adsorbed to the adsorption member 61 from the adsorption member 61. Furthermore, in step S34, the control unit 2 executes one set of tapping action five times. This further removes the paper powder D adsorbed to the adsorption member 61 from the adsorption member 61. The paper powder D removed from the adsorption member 61 is collected in the suction unit 40 by the suction force generated by the negative pressure generator 43 in step S30.

[0091] In step S35, the control unit 2 changes the driving force of the negative pressure generating unit 43, thereby changing the suction force of the negative pressure generating unit 43 back to the first suction force F1 from the second suction force. In step S36, the control unit 2 turns the second power supply 62 back on. Steps S35 and S36 are steps for preparing for the next job.

[0092] If the answer is "all NO" in step S32, in step S37, the control unit 2 executes the flicking action three times. The impact caused by the flicking action removes the paper powder D adsorbed to the adsorption member 61 from the adsorption member 61. Furthermore, in step S38, the control unit 2 executes one set of tapping action three times. This further removes the paper powder D adsorbed to the adsorption member 61 from the adsorption member 61. The paper powder D removed from the adsorption member 61 is collected in the suction unit 40 by the suction force generated by the negative pressure generator 43 in step S30. After step S38 is completed, the control unit 2 proceeds to step S35 and step S36.

[0093] In this way, the removal control during the cleaning operation can ensure a longer allowable execution time than the removal control for each job, so the number of flicks and taps is increased. This makes it possible to remove more of the paper dust D adsorbed to the adsorption member 61. Furthermore, when the control unit 2 determines that the medium is a wide medium or that the medium is being transported at high speed, the amount of paper dust D adsorbed to the adsorption member 61 per unit time increases. Even in this case, the number of tapping operations is increased, so the paper dust D adsorbed to the adsorption member 61 is removed from the adsorption member 61.

[0094] 9, in the case of manual removal control, first, in step S40, the control unit 2 changes the suction force of the negative pressure generating unit 43 to a second suction force greater than the first suction force F1 by switching the driving force of the negative pressure generating unit 43. In step S41, the control unit 2 turns off the second power supply 62.

[0095] During manual execution, the user prioritizes manual removal control over the job, allowing for a decrease in job throughput. That is, during manual execution, the allowable execution time for the impact application operation can be secured longer than during cleaning. During manual execution, removal control changes the control of the negative pressure generator 43 and the second power source 62 to remove more of the paper dust D adsorbed to the adsorption member 61, without significantly reducing job throughput.

[0096] In step S42, the control unit 2 determines at least one of whether the width of the paper M being transported is greater than a predetermined width, and whether the transport speed of the paper M being transported is greater than a predetermined transport speed. In other words, if the paper M is a wide medium or whether the paper M is being transported at high speed, that is, if the answer is "YES" in step S42, the control unit 2 proceeds to step S43. On the other hand, if the answer is neither in step S42, that is, if the answer is "NO to all" in step S42, the control unit 2 proceeds to step S47.

[0097] In step S43, the control unit 2 executes the flicking operation four times. The impact caused by the flicking operation removes the paper powder D adsorbed to the adsorption member 61 from the adsorption member 61. Furthermore, in step S44, the control unit 2 executes one set of tapping operation six times. This further removes the paper powder D adsorbed to the adsorption member 61 from the adsorption member 61. The paper powder D removed from the adsorption member 61 is collected in the suction unit 40 by the suction force generated by the negative pressure generation unit 43 in step S40.

[0098] In step S45, the control unit 2 changes the driving force of the negative pressure generating unit 43, thereby changing the suction force of the negative pressure generating unit 43 back to the first suction force F1 from the second suction force. In step S46, the control unit 2 turns the second power supply 62 back on. Steps S45 and S46 are steps for preparing for the next job.

[0099] If the answer is "all NO" in step S42, in step S47, the control unit 2 executes the flicking action four times. The impact caused by the flicking action removes the paper powder D adsorbed to the adsorption member 61 from the adsorption member 61. Furthermore, in step S48, the control unit 2 executes one set of tapping action four times. This further removes the paper powder D adsorbed to the adsorption member 61 from the adsorption member 61. The paper powder D removed from the adsorption member 61 is collected in the suction unit 40 by the suction force generated by the negative pressure generation unit 43 in step S40. After step S48 is completed, the control unit 2 proceeds to step S45 and step S46.

[0100] In this way, the removal control during manual execution can ensure a longer allowable execution time than the removal control during cleaning operation, so the number of flicks and taps is increased. This makes it possible to remove more of the paper dust D adsorbed to the adsorption member 61. Furthermore, when the control unit 2 determines that the medium is a wide medium or that the medium is being transported at high speed, the amount of paper dust D adsorbed to the adsorption member 61 per unit time increases. Even in this case, the number of tapping operations is increased, so the paper dust D adsorbed to the adsorption member 61 is removed from the adsorption member 61.

[0101] As described above with reference to FIGS. 6 to 9, the impact applying unit performs the impact applying operation in parallel with the maintenance operation for maintaining the liquid ejection unit 80, including the flushing operation and the cleaning operation. Furthermore, the longer the permissible execution time, the more times the impact applying operation is performed. That is, the number of times the impact applying operation is performed when the permissible execution time, which is the time during which the impact applying operation can be performed, is set to the first permissible time, is defined as the first number of times. Furthermore, when the permissible execution time is the second permissible time, which is longer than the first permissible time, the impact applying unit performs the impact applying operation a second number of times, which is greater than the first number of times.

[0102] Furthermore, the suction force of the suction unit 40 increases as the permissible execution time increases. That is, when the permissible execution time, which is the time during which the impact application operation can be performed, is set to a first permissible time, the suction force of the suction unit 40 is set to a first suction force F1. When the permissible execution time is a second permissible time that is longer than the first permissible time, the suction unit 40 uses a second suction force that is greater than the first suction force F1.

[0103] Furthermore, the number of times the impact application operation is performed when the width of the paper M in the direction intersecting the transport direction is defined as a first width is defined as a first number of times. When the width of the paper M is a second width that is longer than the first width, the impact application unit performs the impact application operation a second number of times that is greater than the first number of times.

[0104] Furthermore, the number of times the impact application operation is performed when the speed at which the paper M is transported is the first speed is defined as the first number of times. When the speed at which the paper M is transported is the second speed which is faster than the first speed, the impact application unit performs the impact application operation the second number of times which is greater than the first number of times. Furthermore, the impact application unit performs the impact application operation while suction by the suction unit 40 is maintained.

[0105] As described above, the liquid ejection device 1 of this embodiment can provide the following effects. According to this embodiment, the adsorption member 61, which is located upstream of the liquid discharger 80, is charged with a polarity opposite to the polarity applied to the sheet M by the charging unit 50, so that the paper dust D adhering to the sheet M can be adsorbed to the adsorption member 61 by Coulomb force. As a result, the paper dust D is removed from the sheet M before the sheet M is transported to the liquid discharger 80, thereby suppressing the adhesion of the paper dust D to the liquid discharger 80. Furthermore, since the impact applying unit applies an impact to the adsorption member 61 when the adsorption member 61 is not facing the sheet M, the paper dust D adsorbed to the adsorption member 61 can be removed from the adsorption member 61. As a result, it is possible to suppress the paper dust D from continuing to accumulate on the adsorption member 61, so that the paper dust D adsorbed to the adsorption member 61 does not fall onto the sheet M.

[0106] According to this embodiment, the impact applying unit that applies an impact to the adsorption member 61 has a first displacement member 64 and a second displacement member 65, which are an example of a displacement member that displaces the adsorption member 61. In addition, the impact applying unit has an upper contact member 67 and a lower contact member 68, which are an example of a contact member that can come into contact with the displacing adsorption member 61, so that an impact can be applied to the adsorption member 61. This makes it possible to remove the paper powder D that has been adsorbed to the adsorption member 61 from the adsorption member 61.

[0107] According to this embodiment, the attracting member 61 comes into contact with the upper contact member 67 located above the attracting member 61 by the first displacement member 64, so that an impact can be applied to the attracting member 61. As a result, the paper powder D attracted to the attracting member 61 can be removed from the attracting member 61.

[0108] According to this embodiment, the adsorption member 61 comes into contact with the lower contact member 68 located below the adsorption member 61 by the second displacement member 65, so that an impact can be applied to the adsorption member 61. As a result, the paper powder D adsorbed to the adsorption member 61 can be removed from the adsorption member 61.

[0109] According to this embodiment, the second displacement member 65 is movable along the conveyance direction, and therefore, impacts can be applied to different positions in the conveyance direction on the adsorption member 61. This makes it possible to remove a larger amount of paper powder D adsorbed to the adsorption member 61 from the adsorption member 61.

[0110] According to this embodiment, before starting a job that is a process for discharging liquid onto paper M, or after the job is completed, the impact applying unit applies an impact to the adsorption member 61. This makes it possible to remove the paper dust D adsorbed to the adsorption member 61 for each job. It also makes it possible to prevent the paper dust D removed from the adsorption member 61 from adhering to paper M.

[0111] According to this embodiment, the impact application operation is performed in parallel with the maintenance operation of the liquid discharger 80, which improves the throughput of the job, which is a process for discharging liquid onto the paper M. Furthermore, because the impact application operation is not performed when discharging liquid onto the paper M, no impact occurs to the liquid discharger 80 during the job. This makes it possible to remove the paper dust D adsorbed to the adsorption member 61 without adversely affecting the operation of the job.

[0112] According to this embodiment, the liquid ejection device 1 includes an instruction receiving unit 2A that can receive an instruction to perform an impact application operation, so the user can perform the impact application operation at any timing, thereby improving usability.

[0113] According to this embodiment, when the permissible execution time is a second permissible time that is longer than the first permissible time, the impact applying unit performs the impact applying operation a second number of times that is greater than the first number of times. In other words, by increasing the number of impact applying operations when there is a margin in the permissible execution time, it is possible to remove more of the paper dust D adsorbed to the adsorption member 61 while suppressing a decrease in throughput related to the job.

[0114] According to this embodiment, when the permissible execution time is the second permissible time that is longer than the first permissible time, the suction unit 40 performs suction with the second suction force that is greater than the first suction force F1. In other words, by increasing the suction force when there is sufficient time in the permissible execution time, more of the paper dust D adsorbed to the adsorption member 61 can be removed.

[0115] According to this embodiment, when the width of the sheet M is a second width that is longer than the first width, the impact applying unit performs the impact applying operation a second number of times that is greater than the first number of times. In other words, even if the amount of paper dust D adsorbed to the adsorption member 61 increases as the width of the sheet M increases, by increasing the number of impact applying operations, it is possible to remove more of the paper dust D adsorbed to the adsorption member 61.

[0116] According to this embodiment, when the speed at which the paper sheet M is transported is a second speed that is faster than the first speed, the impact applying unit performs the impact applying operation a second number of times that is greater than the first number of times. In other words, even if the amount of paper dust D adsorbed to the adsorption member 61 increases as a result of high-speed printing, by increasing the number of impact applying operations, it is possible to remove more of the paper dust D adsorbed to the adsorption member 61.

[0117] According to this embodiment, the impact applying unit performs an impact application operation while suction by the suction unit 40 is maintained, so it is possible to collect the paper powder D removed from the adsorption member 61. Furthermore, because an impact is applied to the adsorption member 61 while suction is being performed, the paper powder D removal process and the collection process can be performed in parallel. This makes it possible to improve the throughput of a job that is a process for discharging liquid onto paper M.

[0118] In this embodiment, paper dust D attached to the sheet M or paper dust D generated from the sheet M is adsorbed from the sheet M to the adsorption member 61 by Coulomb force, but this is not limiting. For example, if a film or the like is used as the medium, dust particles, fiber scraps, and other particles attached to the medium may be adsorbed from the medium to the adsorption member 61 by Coulomb force.

[0119] In this embodiment, the paper powder D removed from the adsorption member 61 is collected by utilizing the negative pressure generated by the suction unit 40, but the present invention is not limited to this. The paper powder D may also be collected by utilizing the negative pressure generated by another suction unit provided near both ends of the adsorption member 61 in the width direction along the Y axis, or near one end of the adsorption member 61, for example.

[0120] In the present embodiment, an impact is applied to the adsorption member 61 while the suction unit 40 is applying negative pressure, and the paper powder D removed from the adsorption member 61 is collected, but this is not limiting. After the impact is applied to the adsorption member 61 to remove the paper powder D from the adsorption member 61, the paper powder D removed from the adsorption member 61 may be collected by applying negative pressure to the suction unit 40.

[0121] In this embodiment, the tapping action is performed following the plucking action, but this is not limiting. Only one of the plucking action and the tapping action may be performed, or the plucking action may be performed following the tapping action.

[0122] In this embodiment, the second tapping operation is performed following the first tapping operation, but this is not limiting. Only the first tapping operation may be performed. Furthermore, by switching the rotation speed of the second motor 65C, the magnitude of the first tapping operation and the second tapping operation may be changed in proportion to the amount of paper powder D adsorbed to the adsorption member 61.

[0123] In this embodiment, the holding member 63 is a plurality of tension springs, but is not limited to this. The holding member 63 may be a compression spring that always holds the attraction member 61 facing upward from below.

[0124] In this embodiment, the shaft-shaped second displacement member 65 is displaced to the contact position PS3 to displace the attraction member 61 to the lower contact position P3, but this is not limiting. The member for displacing the attraction member 61 to the lower contact position P3 may be a cam-shaped second displacement member 65 that can displace the attraction member 61 between the standby position PS1, the abutment position PS2, and the contact position PS3.

[0125] Furthermore, instead of the shaft-shaped second displacement member 65, a first displacement member 64 may be used in which a third portion is formed in the first displacement member 64, in which the distance from the first displacement member rotation axis 64C to the outer periphery of the first displacement member 64 is longer than that of the first displacement member high portion 64B. In this case, the third portion is brought into contact with the upper surface of the attraction member 61, thereby displacing the attraction member 61 to the lower contact position P3.

[0126] In this embodiment, the moving unit 66 is a ball screw connected to the third motor 66A, but is not limited to this. The moving unit 66 may be, for example, a rack and pinion, a belt drive, or a linear motor, as long as it can move the second displacement member 65 in the conveying direction. Also, one second displacement member 65 may be provided at each of the four corners of the attraction member 61.

[0127] In this embodiment, the instruction receiving unit 2A is provided in the control unit 2, but this is not limiting. The instruction receiving unit 2A may be an external device such as a computer that can communicate with the liquid ejection device 1.

[0128] In this embodiment, an inkjet printer equipped with a line head has been exemplified as the liquid ejection device 1, but the liquid ejection device 1 is not limited to this. The liquid ejection device 1 may also be a serial printer, a page printer, or the like. [Explanation of symbols]

[0129] 1...liquid ejection device, 2...control unit, 2A...instruction receiving unit, 10...casing, 11...discharge port, 20...feed unit, 21...feed cassette, 22...pickup roller, 23...feed guide, 24...feed roller pair, 25...feed path, 26...registration roller pair, 30...conveying unit, 31...conveying belt, 31A...conveying surface, 32...conveying drive roller, 33...tension roller, 34...guide roller, 35...belt peripheral speed detection roller, 36...pressure roller, 40...suction unit, 41...platen, 42...air circulation guide, 43...negative pressure generating unit, 44...exhaust port, 50...charging unit, 51...charging electrode, 52...first power source, 60...suction unit, 61...suction member, 61A...suction unit housing, 61B...shaft window, 62...second power source, 63...holding member, 64...first displacement member, 64A...lower portion of first displacement member, 64B...higher portion of first displacement member, 64C...first displacement member rotation shaft, 64D...first motor, 65...second displacement member, 65A...tip of second displacement member, 65B...second displacement member rotation shaft, 65C...second motor, 66...moving portion, 66A...third motor, 67...upper contact member, 67A...lower portion of upper contact member, 68...lower contact member, 68A...upper portion of lower contact member, 70...static charge removal portion, 71...static charge removal electrode, 72...third power source, 80...liquid discharge portion, 81...maintenance portion, 90...discharge portion, 91...discharge guide, 92...pair of discharge rollers, 93...discharge tray, F1...first suction force, P1...home position, P2...upper contact position, P3...lower contact position, PS1...standby position, PS2...abutment position, PS3...contact position, PS4...upstream position, PS5...downstream position.

Claims

1. a conveyor belt that rotates to convey the medium in a conveyance direction; a charging unit that charges the medium being transported in the transport direction; an attracting member located downstream of the charging unit in the transport direction and facing the transport belt, the attracting member being charged to a polarity opposite to the polarity applied to the medium by the charging unit; an impact applying unit that applies an impact to the suction member; a suction unit that sucks air near the adsorption member; a liquid discharge unit located downstream of the adsorption member in the transport direction and configured to discharge liquid onto the medium, The liquid ejection device, wherein the impact applying unit applies the impact while the suction member is not facing the medium being transported by the transport belt.

2. a holding member that holds the attraction member in a displaceable manner, The impact applying unit has a displacement member that displaces the attraction member and a contact member that can come into contact with the displaced attraction member. The liquid ejection device according to claim 1 .

3. the contact member includes a first contact member provided above the adsorption member, the displacement member includes a first displacement member that causes the attraction member to contact the first contact member; The liquid ejection device according to claim 2 .

4. the contact member includes a second contact member provided below the attraction member, the displacement member includes a second displacement member that causes the attraction member to contact the second contact member; The liquid ejection device according to claim 2 or 3.

5. the second displacement member is movable along the conveying direction; The liquid ejection device according to claim 4 .

6. the impact applying unit performs the impact applying operation before starting a job that is a process for discharging the liquid onto the medium, or after the job is completed. The liquid ejection device according to claim 1 .

7. the impact applying unit performs the impact applying operation in parallel with a maintenance operation for performing maintenance on the liquid ejection unit. The liquid ejection device according to claim 1 .

8. an instruction receiving unit capable of receiving an instruction to perform the impact applying operation; The liquid ejection device according to claim 1 .

9. When an execution permissible time, which is a time during which the impact applying operation can be performed, is a first permissible time, and the number of times the impact applying operation is performed is a first number of times, if the execution permissible time is a second permissible time that is longer than the first permissible time, the impact applying unit performs the impact applying operation a second number of times that is greater than the first number of times; The liquid ejection device according to claim 1 .

10. When an execution permissible time, which is a time during which the impact applying operation can be performed, is a first permissible time, and the suction force by the suction unit is a first suction force, if the execution permissible time is a second permissible time that is longer than the first permissible time, The suction unit applies the suction force with a second suction force greater than the first suction force. The liquid ejection device according to claim 1 .

11. When the width of the medium in the direction intersecting the transport direction is a first width, the number of times the impact applying operation is performed is defined as a first number. When the width of the medium is a second width that is longer than the first width, the impact applying unit performs the impact applying operation a second number of times that is greater than the first number of times; The liquid ejection device according to claim 1 .

12. When the speed at which the medium is transported is a first speed, the number of times the impact application operation is performed is defined as a first number of times. When the speed at which the medium is transported is a second speed that is faster than the first speed, the impact applying unit performs the impact applying operation a second number of times that is greater than the first number of times; The liquid ejection device according to claim 1 .

13. The impact applying unit performs the impact applying operation while the suction unit maintains suction. The liquid ejection device according to claim 1 .

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