JP2017128032A - Printing apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a printing apparatus capable of inhibiting a conveyance belt to which a medium is electrostatically adsorbed from contacting a print head.SOLUTION: A printing apparatus 10 includes an endless conveyance belt 73 to which a medium M is electrostatically adsorbed and which rotates to convey the medium M in a conveyance direction Y, a print head 31 which performs printing on a print surface Mb of the medium M electrostatically adsorbed to the conveyance belt 73, a charge elimination section 92 which is arranged upstream in the conveyance direction Y of the print head 31 and eliminates charge from the print surface Mb of the medium M by contacting the print surface Mb of the medium M electrostatically adsorbed to the conveyance belt 73, and a backup plate 74 which supports the conveyance belt 73 by contacting an inner surface 73a of the conveyance belt 73. When a position opposing the charge elimination section 92 with the conveyance belt 73 sandwiched therebetween is set as an opposite position FP, the backup plate 74 is provided at the opposite position FP and a position downstream in the conveyance direction Y of the opposite position FP.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a printing apparatus such as an ink jet printer.

  Conventionally, printing is performed by ejecting ink onto a conveyance belt that conveys a medium such as paper in a state in which the medium is electrostatically adsorbed, a charging unit (charging roller) that charges the conveyance belt, and a medium conveyed on the conveyance belt. A printing apparatus including a print head is known (for example, Patent Document 1).

JP 2005-247479 A

  By the way, in the printing apparatus as described above, when the conveyance belt is slack, the conveyance belt may be lifted toward the print head due to an electrostatic adsorption force generated between the charged conveyance belt and the print head. In this case, when the conveyance belt comes into contact with the print head and the rotation speed of the conveyance belt changes, printing cannot be performed normally, and print quality may be deteriorated.

  The present invention has been made in view of the above circumstances. An object of the present invention is to provide a printing apparatus capable of suppressing the conveyance belt that electrostatically attracts the medium from coming into contact with the print head.

Hereinafter, means for solving the above-described problems and the effects thereof will be described.
A printing apparatus that solves the above-described problems is provided on an endless conveyance belt that rotates to convey a medium in the conveyance direction while electrostatically adsorbing the medium, and a printing surface of the medium that is electrostatically adsorbed to the conveyance belt. A print head for performing printing, a charge removing unit disposed upstream of the print head in the transport direction and contacting the print surface of the medium to remove charges from the print surface of the medium; and an inner surface of the transport belt A belt support portion that supports the conveyor belt, and when the position facing the static eliminator and the conveyor belt is defined as an opposite position, the belt support portion includes the opposite position and It is provided at at least one of the positions downstream of the facing position in the transport direction.

  According to the above configuration, the neutralization unit that removes charges from the print surface by contacting the print surface of the medium electrostatically attracted to the transport belt is provided upstream of the print head in the transport direction. For this reason, when the conveyance belt does not convey the medium, the static elimination unit comes into contact with the conveyance belt and weakens the electrostatic adsorption force with respect to the print head by the conveyance belt, thereby making it difficult for the conveyance belt to be adsorbed to the print head.

  Further, in the above configuration, the belt support portion is provided at at least one of the facing position and the position downstream of the facing position in the transport direction. For this reason, a conveyance resistance is provided to the said conveyance belt because a load acts on the conveyance belt in the direction which cross | intersects a conveyance direction by such a belt support part and a static elimination part. Therefore, even if the conveyance belt is loosened in the conveyance direction upstream of the static elimination unit, the conveyance belt is less likely to be loosened in the conveyance direction downstream of the static elimination unit. Thus, contact between the conveyor belt and the print head can be suppressed.

In the printing apparatus, it is preferable that the belt support portion is made of a conductive material and is grounded.
According to the above configuration, it is possible to suppress unintentional charging of the conveyor belt due to friction with the belt support portion accompanying the rotation of the conveyor belt, and to suppress a decrease in electrostatic attraction force to the medium by the conveyor belt. it can.

In the printing apparatus, it is preferable that the static eliminating unit includes a brush that contacts a printing surface of the medium.
According to the above configuration, it is possible to realize a configuration for removing charges from the printing surface of the medium with a simple configuration.

In the printing apparatus, it is preferable that a contact pressure of the charge eliminating unit with respect to the transport belt is uniform in a width direction intersecting the transport direction.
When the contact pressure of the static eliminating portion is not uniform in the width direction, there is a possibility that a part of the conveyance belt in the width direction may be loosened. In this respect, according to the above-described configuration, the contact pressure of the static eliminator is uniform in the width direction, so that the occurrence of the above situation can be suppressed.

In the printing apparatus, it is preferable that the contact pressure of the charge removal unit with respect to the transport belt is adjustable.
According to the above configuration, when the charge needs to be removed from the printing surface of the medium such as when printing on the medium, the contact pressure is increased, while from the printing surface of the medium when printing is not performed on the medium. When there is no need to remove the charge, the contact pressure can be lowered. For this reason, when it is not necessary to neutralize the printing surface of a medium, it can suppress that a static elimination part deteriorates (for example, deformation | transformation) by continuing the state with a high contact pressure.

  The printing apparatus includes a control unit that controls a charge amount of the transport belt, and the control unit increases the contact pressure when increasing the charge amount than when decreasing the charge amount. Is desirable.

  When the charge amount of the transport belt is increased, the charge amount of the medium that contacts the transport belt is also increased compared to when the charge amount is decreased. For this reason, in this case, if the neutralization on the printing surface of the medium is insufficient, the electrostatic attraction force to the medium by the conveyor belt may be reduced.

  In this regard, according to the above configuration, when the charge amount of the transport belt is increased, the contact pressure is increased as compared with the case where the charge amount is decreased, and more charges are removed from the printing surface of the medium. Therefore, even when the charge amount of the transport belt is increased, it is possible to suppress a decrease in electrostatic attraction force to the medium by the transport belt.

  In the printing apparatus, it is preferable that the control unit increases the amount of charge when the transport belt transports the medium that is easily bent compared to when transporting the medium that is not easily bent. .

  According to the above configuration, when the medium that tends to bend is transported, the amount of charge of the transport belt is larger than when the medium that is difficult to bend is transported. Lifting from the belt can be suppressed. That is, it is possible to suppress the ink landing on a position different from the original as a result of the medium floating from the conveyance belt coming into contact with the print head or the medium posture changing by floating from the conveyance belt.

In the printing apparatus, it is preferable that the control unit increases the charge amount when performing double-sided printing on the medium than when performing single-sided printing on the medium.
When printing is performed on both sides of the medium, the medium may be more likely to bend than when printing is performed on one side of the medium. In this regard, according to the above configuration, when performing duplex printing on a medium, the amount of charge on the conveyor belt is larger than when performing single-sided printing. Therefore, when performing duplex printing, the medium is curved on the conveyor belt. By doing so, it is possible to suppress floating from the conveyor belt.

  In the printing apparatus, the print head performs printing by ejecting ink onto the medium, and the control unit determines whether the ink ejection amount is large when the ink ejection amount onto the medium is large. It is desirable to increase the charge amount compared to the case where the amount is small.

  When the amount of ink discharged to the medium increases, the medium may be easily bent due to the large amount of ink absorbed by the medium. In this regard, according to the above configuration, when the amount of ink discharged to the medium is large, the amount of charge on the transport belt is increased compared to the case where the amount of ink discharged is small. For this reason, regardless of the amount of ink discharged to the medium, it is possible to suppress the medium from being lifted from the conveyor belt by being curved on the conveyor belt.

In the printing apparatus, it is preferable that the control unit increases the charge amount when the thickness of the medium is small as compared to when the thickness is large.
The thinner the medium is, the lower the rigidity of the medium is. Therefore, the thinner the medium is, the easier the medium is curved on the conveyor belt. In this respect, according to the above configuration, when the thickness of the medium is small, the amount of charge of the conveyance belt is increased as compared with the case where the medium is thick, so that the medium is curved on the conveyance belt regardless of the thickness of the medium. It is possible to suppress lifting from the conveyor belt.

In the printing apparatus, it is preferable that the control unit increases the charge amount when the gap between the print head and the medium is narrow as compared with when the gap is wide.
When the distance between the print head and the medium is narrow, there is a high possibility that the medium floating from the conveyance belt contacts the print head even when the amount of the medium floating from the conveyance belt is small. In this regard, according to the above configuration, when the interval is narrow, the amount of charge of the transport belt is increased compared to when the interval is wide, so that the medium floating from the transport belt can be prevented from coming into contact with the print head. .

The printing apparatus preferably includes a wiping unit that wipes an outer surface of the conveyance belt in a path that is not the medium conveyance path among the circulation paths of the conveyance belt.
According to the above configuration, the foreign matter (hereinafter also referred to as “attachment”) attached to the transport belt can be removed by the wiping unit by transporting the medium or performing printing. In this way, it is possible to suppress a decrease in electrostatic attraction force to the medium by the conveyance belt due to the deposits.

  When the wiping unit wipes the outer surface of the transport belt, the printing apparatus holds the transport belt together with the wiping unit in a width direction intersecting the transport direction by contacting the inner surface of the transport belt. A clamping part is provided.

  When the wiping unit wipes the outer surface of the conveyor belt, if the conveyor belt is displaced away from the wiping unit, the outer surface of the conveyor belt cannot be wiped normally, for example, a portion where the conveyor belt and the wiping unit do not contact with each other occurs. There is a fear. In this regard, according to the above configuration, when the wiping unit wipes the outer surface of the conveyance belt, the conveyance unit is sandwiched between the wiping unit and the clamping unit by contacting the clamping unit with the inner surface of the conveyance belt. Displacement in a direction away from the wiping portion is restricted. Therefore, when the wiping unit wipes the transport belt, it is possible to easily remove the deposits on the transport belt.

1 is a side view illustrating a schematic configuration of a printing apparatus according to an embodiment. FIG. 3 is a side view illustrating a schematic configuration of an electrostatic conveyance unit of the printing apparatus. The side view which shows typically the mode of the electrostatic attraction of the medium with a conveyance belt. FIG. 2 is a block diagram showing an electrical configuration of the printing apparatus. A map showing the relationship between the charge amount and the contact pressure. The map which shows the relationship between the ink discharge amount and the charge amount. The map which shows the relationship between the thickness of a medium, and a charge amount. The map which shows the relationship between the space | interval of a print head and a medium, and a charging amount.

  Hereinafter, an embodiment of a printing apparatus will be described with reference to the drawings. Note that the printing apparatus of the present embodiment is an ink jet printer that forms characters and images by ejecting ink onto a medium such as paper.

  As shown in FIG. 1, a transport device 20 that transports a medium M along a transport path and a printing unit 30 that performs printing on the transported medium M are provided in the casing 11 of the printing apparatus 10 according to the present embodiment. And are provided. In FIG. 1, when the direction perpendicular to the paper surface is the width direction X of the medium M, the conveyance path is formed so as to convey the medium M in a direction intersecting (orthogonal) with the width direction X of the medium M.

  In the following description, the direction in which the medium M is transported is “transport direction Y”, and the vertical direction is “vertical direction Z”. Here, the transport direction Y is a direction intersecting (orthogonal) with the width direction X, and the vertical direction Z is a direction intersecting (orthogonal) with the width direction X. Further, the direction opposite to the transport direction Y is also referred to as upstream in the transport direction, and the transport direction Y is also referred to as downstream in the transport direction.

  The printing unit 30 includes a line head type print head 31 that can simultaneously eject ink, which is an example of a color material, over substantially the entire width direction X of the medium M. Then, the ink ejected from the nozzles 32 (see FIG. 2) formed on the print head 31 adheres to the medium M, whereby printing on the printing surface of the medium M is performed. Incidentally, in the print head 31 capable of ejecting a plurality of colors of ink, a nozzle array composed of a plurality of nozzles 32 that eject the same color ink is formed in the width direction X, and the nozzle array ejecting different colors of ink is conveyed in the transport direction Y. It is formed to line up.

  The transport device 20 includes a discharge mechanism unit 40 that discharges the printed medium M to the outside of the housing 11, and a feeding mechanism unit 50 that feeds the medium M before printing along the transport path. Here, the discharge mechanism unit 40 is provided on the downstream side in the transport direction, and the feeding mechanism unit 50 is provided on the upstream side in the transport direction.

  The discharge mechanism unit 40 includes a plurality of discharge rollers 41, 42, 43, 44, and 45 arranged along the transport path. The discharge rollers 41 to 45 each include a drive roller 46 that imparts a transport force to the medium M by being rotationally driven, and a driven roller 47 that is driven to rotate as the medium M is transported. The driving roller 46 and the driven roller 47 have the width direction X as the rotation axis direction, and the driven roller 47 is urged toward the driving roller 46. The cross-sectional shape that intersects the width direction X of the drive roller 46 is circular, while the cross-sectional shape that intersects the width direction X of the driven roller 47 is a substantially star shape. That is, the driven roller 47 is a roller in contact with the surface on which the medium M is printed, so that the contact area with the surface becomes as small as possible.

  Then, the medium M conveyed by the discharge mechanism unit 40 is discharged out of the housing 11 from the discharge port 48 formed in the housing 11. That is, the discharge port 48 is the downstream end of the transport path, that is, the most downstream of the transport path. And the medium M discharged | emitted from the discharge port 48 is mounted in the lamination | stacking state on the mounting base 49, as shown with a dashed-two dotted line in FIG.

  The feeding mechanism unit 50 includes a first medium supply unit 51, a second medium supply unit 52, a third medium supply unit 53, and an electrostatic transport unit 70. The first medium supply unit 51, the second medium supply unit 52, and the third medium supply unit 53 convey the medium M toward the electrostatic conveyance unit 70, and the electrostatic conveyance unit 70 is directed toward the discharge mechanism unit 40. Then, the medium M is conveyed.

  A cover 12 that can be opened and closed is provided on one side surface (right side surface in FIG. 1) of the housing 11, and the insertion opening 13 is exposed by opening the cover 12. The first medium supply unit 51 includes a first feeding roller 54 that holds the medium M inserted into the housing 11 from the insertion port 13. Then, the medium M is transported toward the electrostatic transport unit 70 by the rotation of the first feeding roller 54.

  In addition, a feeding cassette 55 in which the medium M before printing is set in a stacked state is provided at the lower portion of the housing 11. The second medium supply unit 52 is a supply unit for feeding the medium M from the feeding cassette 55. That is, the second medium supply unit 52 suppresses the pick-up roller 56 that feeds the uppermost medium M in the feeding cassette 55 out of the feeding cassette 55 and the plurality of media M from being conveyed in an overlapping manner. A separation roller 57 and a second feeding roller 58 that sandwiches one medium M that has passed through the separation roller 57 are provided. Then, the medium M is transported toward the electrostatic transport unit 70 by the rotation of the pickup roller 56, the separation roller 57, and the second feeding roller 58.

  The third medium supply unit 53 supplies a medium M on which one side has been printed to the electrostatic transport unit 70 again when performing double-sided printing for printing on both sides of the medium M. It is. The third medium supply unit 53 is connected to the first conveyance path 61 leading to the discharge port 48 or the second conveyance path 62 branched from the first conveyance path 61 downstream of the electrostatic conveyance unit 70 in the conveyance direction. A branching mechanism 64 that switches the transport path of the medium M is provided. In the third medium supply unit 53, a branch conveyance roller 65 is provided in the second conveyance path 62, and a plurality of reverse conveyance rollers 66 are provided in the third conveyance path 63 branched from the second conveyance path 62. Is provided.

  When duplex printing is performed, the medium M on which one side has been printed is guided from the electrostatic conveyance unit 70 to the second conveyance path 62 by the branch mechanism 64. At this time, the medium M is transported downstream in the transport direction by the rotation of the branch transport roller 65 in the forward direction. When the rear end of the medium M is guided to the second transport path 62, the branch transport roller 65 is rotated in the reverse direction, and the medium M is transported in the reverse direction. Then, the medium M is guided to the third conveyance path 63 positioned above the printing unit 30 in FIG. 1, and the medium M is moved along the third conveyance path 63 by the rotation of the plurality of reverse conveyance rollers 66. Be transported. As a result, the medium M is joined to the first transport path 61 upstream of the electrostatic transport unit 70 in the transport direction, and the medium M is guided to the electrostatic transport unit 70 again.

  When the medium M is guided again to the electrostatic transport unit 70 in this way, the printed surface comes into contact with the electrostatic transport unit 70, and the non-printed surface faces the print head 31. In the following description, the surface of the medium M that contacts the electrostatic transport unit 70 is also referred to as “back surface Ma”, and the surface opposite to the back surface Ma is also referred to as “printing surface Mb”.

  Further, in the printing apparatus 10 of the present embodiment, after the third medium supply unit 53 finishes printing with the first surface of the both sides of the medium M as the printing surface Mb, the second surface is the printing surface Mb. Thus, a “reversing mechanism” that reverses the front and back of the medium M and guides the medium M to the electrostatic transport unit 70 is configured.

Next, with reference to FIG. 2, the structure of the electrostatic conveyance part 70 and its peripheral member is demonstrated.
As shown in FIG. 2, in the electrostatic conveyance unit 70, a first belt roller 71 is disposed upstream of the print head 31 in the conveyance direction, and a second belt roller 72 is disposed downstream of the print head 31 in the conveyance direction. Has been placed. The first belt roller 71 and the second belt roller 72 have the width direction X as the rotation axis direction. The first belt roller 71 is a roller that is connected to a drive source (not shown) and can be driven to rotate, and the second belt roller 72 is a roller that is not connected to a drive source and cannot be driven to rotate.

  An endless (annular) conveyance belt 73 is wound around the first belt roller 71 and the second belt roller 72. The conveyor belt 73 is made of an elastic rubber material or resin material. Here, as indicated by the white arrow in FIG. 2, the second belt roller 72 is biased in a direction away from the first belt roller 71 (left side in the figure). Therefore, tension is applied to the transport belt 73 in the rotational direction of the transport belt 73 by the second belt roller 72.

  In the present embodiment, the print head 31 is disposed at a position downstream of the intermediate position P1 of the conveyance belt 73 in the conveyance direction Y with respect to the conveyance direction. Specifically, the center position P2 in the transport direction Y of the print head 31, that is, the center position P2 in the transport direction Y of the nozzle formation region of the print head 31 is located downstream of the intermediate position P1 of the transport belt 73 in the transport direction. .

  Then, when the first belt roller 71 is rotationally driven, the transport belt 73 rotates and the medium M is transported in the transport direction Y. When the transport belt 73 transports the medium, the outer surface of the transport belt 73 contacts the back surface Ma of the medium M and functions as a support surface that supports the medium M.

  In the following description, the surface of the transport belt 73 that contacts the first belt roller 71 and the second belt roller 72 is referred to as an “inner surface 73 a”, and when the medium M is supported by the transport belt 73, the back surface Ma of the medium M is used. The contact surface is referred to as an “outer surface 73b”. A path along which the conveyor belt 73 moves when the conveyor belt 73 rotates is also referred to as a “circular path”.

  As shown in FIG. 2, a backup plate 74 that supports the conveyor belt 73 by contacting the inner surface of the conveyor belt 73 is provided immediately below the print head 31 and inside the circulation path of the conveyor belt 73. Yes. The backup plate 74 is preferably made of a conductive material such as metal and grounded. Further, as indicated by the white arrow in FIG. 2, the backup plate 74 biases the transport belt 73 toward the print head 31. Therefore, tension is applied to the transport belt 73 in the rotational direction of the transport belt 73 by the backup plate 74. In this respect, in the present embodiment, the backup plate 74 corresponds to an example of a “belt support portion”.

  As shown in FIG. 2, a wiping portion 75 that wipes the outer surface 73 b of the conveyor belt 73 is provided vertically below the conveyor belt 73. The wiping unit 75 includes a cleaning blade 76 that contacts the outer surface 73 b of the conveyance belt 73, and a blade support unit 77 that supports the cleaning blade 76.

  The cleaning blade 76 is made of, for example, a resin material such as a PET (polyethylene terephthalate) film, and has substantially the same length as the transport belt 73 in the width direction X. The blade support portion 77 can bias the outer surface 73 b of the conveyance belt 73 around which the cleaning blade 76 is wound between the first belt roller 71 and the second belt roller 72 toward the inside of the conveyance belt 73. Thus, the cleaning blade 76 is supported. And the wiping part 75 is the outer surface of the conveyance belt 73 in the path | route which is not the conveyance path | route of the medium M among the circulation paths of the conveyance belt 73 by sliding with the outer surface 73b of the said conveyance belt 73 accompanying rotation of the conveyance belt 73. Wipe 73b.

  The blade support portion 77 may be movable up and down to change the distance from the conveyor belt 73. According to this, the contact pressure of the cleaning blade 76 with respect to the conveyance belt 73 can be changed, or the cleaning blade 76 can be kept out of contact with the conveyance belt 73.

  Further, at a position facing the wiping unit 75 and the conveyance belt 73, a clamping unit 78 that clamps the conveyance belt 73 together with the wiping unit 75 is provided. The sandwiching portion 78 is provided along the inner surface 73 a in a state where it is in contact with the inner surface 73 a of the conveyor belt 73 urged by the wiping portion 75. For this reason, when the conveyance belt 73 is wiped by the wiping unit 75, the clamping unit 78 holds the conveyance belt 73 in the width direction X together with the wiping unit 75.

  As shown in FIG. 2, the medium M supplied from the first medium supply unit 51, the second medium supply unit 52, or the third medium supply unit 53 is disposed upstream of the conveyance belt 73 in the conveyance direction. A supply roller 81 that conveys toward the center 73 is provided. The supply roller 81 includes a drive roller 82 that imparts a transport force to the medium M by driving and rotating, and a driven roller 83 that rotates by contacting the medium M to be transported. The driven roller 83 is urged toward the driving roller 82. Further, the driving roller 82 and the driven roller 83 have a width direction X as a rotation axis direction, and a cross-sectional shape intersecting the width direction X is circular.

  The supply roller 81 transports the medium M downstream in the transport direction in the rotationally driven state, while not transporting the medium M in the transport direction Y in the rotation stopped state. Specifically, in the supply roller 81 in the rotation stopped state, the drive roller 82 is rotationally driven with the drive roller 82 and the driven roller 83 sandwiching the medium M, whereby the medium M is transported in the transport direction. On the other hand, in the rotation stop state, the drive roller 82 is not rotated, so that the medium M is not transported in the transport direction Y. Furthermore, in the rotation stop state, a gap through which the medium M passes is not formed between the driving roller 82 and the driven roller 83, so that even if the medium M is transported in the transport direction Y from the upstream in the transport direction, the transport of the medium M is performed. Is limited.

  As shown in FIG. 2, a charging roller 84, which is an example of a charging unit, is provided upstream of the first belt roller 71 in the transport direction (right side in the drawing). The charging roller 84 is in contact with the outer surface 73 b of the conveyor belt 73 with the width direction X as the rotation axis direction. The charging roller 84 is connected to a power supply device 85 that applies a DC voltage to the charging roller 84.

  Then, the rotation of the first belt roller 71 is transmitted to the charging roller 84 through the conveyance belt 73, so that the charging roller 84 is driven to rotate with respect to the first belt roller 71. At this time, the charging roller 84 supplies electric charge to a portion of the outer surface 73 b of the transport belt 73 that is in contact with the charging roller 84. In the printing apparatus 10 according to the present embodiment, the charging roller 84 supplies positive charge to the transport belt 73 and charges the outer surface 73b of the transport belt 73 with positive charge.

  A support roller 86 that presses the medium M transported to the electrostatic transport unit 70 against the transport belt 73 is provided upstream of the print head 31 in the transport direction (right side in the drawing). The support roller 86 is made of, for example, a conductive material such as metal and is grounded. Then, the rotation of the first belt roller 71 is transmitted to the support roller 86 through the conveyance belt 73, so that the support roller 86 is driven to rotate with respect to the first belt roller 71.

  As shown in FIG. 2, a static eliminator 90 is provided between the support roller 86 and the print head 31 in the transport direction Y. The static eliminator 90 includes a static eliminator 92 having a brush 91 protruding toward the conveyor belt 73, and an operating unit 93 that adjusts the contact pressure of the static eliminator 92 against the conveyor belt 73 (medium M).

  The brush 91 may be formed of a material that can remove charges from the medium M (for example, a resin material such as conductive nylon), and may be a thread-like brush. In the present embodiment, the brush 91 is formed so that the contact pressure with respect to the transport belt 73 (medium M) when contacting the transport belt 73 (medium M) is uniform in the width direction X.

  The operating unit 93 includes a mechanism that can linearly move the static eliminating unit 92 such as a solenoid. Then, the operating unit 93 adjusts the contact pressure of the neutralizing unit 92 with respect to the conveyance belt 73 (medium M) by changing the position of the neutralizing unit 92 as indicated by a double-directional arrow in FIG. For example, when it is necessary to neutralize the printing surface Mb of the medium M, the operating unit 93 brings the neutralizing unit 92 into contact with the conveying belt 73 with a contact pressure that causes the outer surface of the conveying belt 73 to bend. On the other hand, the operation unit 93 causes the neutralization unit 92 to retract from the conveyance belt 73 when it is not necessary to neutralize the printing surface Mb of the medium.

  As shown in FIG. 2, the static eliminator 90 (the static eliminator 92) described above is arranged on the upstream side in the transport direction from the print head 31. For this reason, it can be said that the wiping unit 75 described above is provided on the side opposite to the print head 31 when viewed from the static eliminator 90 (the static eliminator 92) in the rotation direction of the conveyance belt 73. It can be said that it is provided between the wiping unit 75 and the charge removal unit 92 in the rotation direction of the transport belt 73. Further, if the position facing the charge removal unit 92 and the conveying belt 73 is “opposed position FP”, the backup plate 74 described above is provided at the opposite position FP and the position downstream of the opposed position FP in the conveying direction. It can be said.

Next, the electrostatic adsorption of the medium M by the transport belt 73 will be described in detail with reference to FIG.
As shown in FIG. 3, the transport belt 73 includes an annular conductive layer 731 and an annular insulating layer 732 formed outside the conductive layer 731. The insulating layer 732 is configured to have an electric resistance larger than that of the conductive layer 731. Note that the outer surface of the insulating layer 732 is the outer surface 73 b of the transport belt 73, and the inner surface of the conductive layer 731 is the inner surface 73 a of the transport belt 73.

  When the conveyance belt 73 is rotated by the rotation of the first belt roller 71, the charging roller 84 is driven to rotate, so that a positive charge (+) is generated on the outer surface 73b side of the conveyance belt 73, that is, on the outer surface side of the insulating layer 732. Is charged, and a negative charge (−) is charged on the inner surface side of the insulating layer 732.

  When the medium M is pressed against the outer surface 73 b of the conveyance belt 73 by the support roller 86, the medium M comes into close contact with the conveyance belt 73 and polarization occurs inside the medium M. That is, a negative charge is charged on the back surface Ma side of the medium M, while a positive charge is charged on the print surface Mb side opposite to the back surface Ma of the medium M. Thereafter, the positive charge charged on the printing surface Mb side of the medium M is removed by the charge eliminating unit 92 (brush 91) that contacts the printing surface Mb, so that the electrostatic attraction force of the conveying belt 73 to the medium M is increased. Occur.

  That is, as in this embodiment, when the conveyance belt 73 is charged with only positive charges (DC charging), the conveyance belt 73 is alternately charged with positive charges and negative charges (AC charging). In contrast, since the adjacent areas in the transport direction Y on the printing surface Mb side of the medium M are charged with the same polarity, the charges are not naturally neutralized between the adjacent areas. For this reason, after the electric charge on the printing surface Mb of the medium M is removed, an electrostatic adsorption force to the medium M by the transport belt 73 is generated.

  On the other hand, when the transport belt 73 is rotated, the conductive layer 731 of the transport belt 73 and the backup plate 74 may come into sliding contact, and the conductive layer 731 of the transport belt 73 may be frictionally charged unintentionally. In this case, since the charging mode of the conductive layer 731 affects the charging mode of the insulating layer 732, the positive charge amount on the outer surface 73 b of the transport belt 73 may be reduced.

  In this regard, in the printing apparatus 10 of the present embodiment, since the backup plate 74 is grounded, the conductive layer 731 is suppressed from being frictionally charged. Therefore, in the transport belt 73, the charging mode of the conductive layer 731 is suppressed from affecting the electrostatic attraction force of the transport belt 73 to the medium M.

Thus, in the present embodiment, the medium M is conveyed in the conveyance direction Y by rotating the conveyance belt 73 while the conveyance belt 73 electrostatically attracts the medium M.
Next, the electrical configuration of the printing apparatus 10 will be described with reference to FIG. Note that, in FIG. 4, for easy understanding of the description, only the configuration that is a main part in describing the operational effects of the printing apparatus 10 of the present embodiment is illustrated.

  As illustrated in FIG. 4, the printing apparatus 10 includes a control unit 100 that comprehensively controls each component. The output side interface of the control unit 100 includes the print head 31, the power supply device 85, the first belt roller 71, the drive roller 82 that configures the supply roller 81, the drive roller 46 that configures the discharge roller 41, and the operation unit 93. Is connected.

  Then, the control unit 100 drives the components related to the conveyance of the medium M, such as the conveyance belt 73, thereby conveying the medium M in the conveyance direction Y, and controlling the drive of the print head 31. Ink is ejected. In this way, printing is performed on the printing surface Mb of the medium M transported in the transport direction Y.

  In addition, the control unit 100 changes the magnitude of the DC voltage applied to the charging roller 84 by controlling the driving of the power supply device 85. For example, when the DC voltage applied to the charging roller 84 is increased, the charge charged to the transport belt 73 charged by the charge roller 84 and the medium M charged by the transport belt 73 also increases. As a result, the electrostatic adsorption force with respect to the medium M by the conveyance belt 73 is increased. That is, the control unit 100 controls the driving of the power supply device 85 to adjust the amount of charge charged by the charging roller 84 and change the electrostatic attraction force of the transport belt 73 to the medium M.

  The control unit 100 drives the supply roller 81 and the first medium supply unit 51, the second medium supply unit 52, or the third medium supply unit 53 that conveys the medium M to the supply roller 81. Control is performed to perform a skew feeding operation for eliminating the inclination of the medium M conveyed to the conveyance belt 73. Specifically, the control unit 100 causes the first medium supply unit 51, the second medium supply unit 52, or the third medium supply unit 53 to convey the medium M in the conveyance direction Y, and the supply roller 81. Is stopped. Thus, the medium M is further transported in the transport direction Y after the leading end of the medium M contacts the driving roller 82 and the driven roller 83 constituting the supply roller 81, so that the medium M is inclined with respect to the transport direction Y. If so, the tilt is eliminated. Thereafter, the control unit 100 allows the supply roller 81 to be rotationally driven, thereby allowing the medium M, whose skew has been eliminated, to be conveyed toward the conveyance belt 73.

  Now, in the printing apparatus 10 that transports the medium M by the transport belt 73 that electrostatically attracts the medium M, it is necessary to change the electrostatic attracting force on the medium M according to the type and state of the medium M to be transported. May occur. In this embodiment, in such a case, the control unit 100 can change the electrostatic attraction force of the conveyance belt 73 on the medium M by adjusting the DC voltage applied to the charging roller 84.

  However, even if the charge amount CV of the conveyance belt 73 is increased, if the charge removal on the printing surface Mb of the medium M is insufficient and the charge remains on the printing surface Mb side of the medium M, the medium by the conveyance belt 73 The electrostatic attraction force with respect to M may be reduced. Accordingly, in the present embodiment, the control unit 100 increases the charge surface Cb of the medium M of the static elimination unit 92 (brush 91) when increasing the charge amount CV of the transport belt 73 than when decreasing the charge amount CV. Increase the contact pressure against. Incidentally, since the charge amount CV of the transport belt 73 has a correlation with the DC voltage applied to the charging roller 84 by the power supply device 85, the contact of the charge removing unit 92 according to the voltage value applied to the charging roller 84 by the power supply device 85. In other words, the pressure can be changed.

  FIG. 5 shows a map showing the relationship between the charge amount CV of the transport belt 73 and the contact pressure CP of the charge removal unit 92 (brush 91) with respect to the medium M. According to the map shown in FIG. 5, the first contact pressure CP1, which is the contact pressure CP when the charge amount CV of the transport belt 73 is the first charge amount CV1, is larger than the first charge amount CV1. It is made smaller than the second contact pressure CP2, which is the contact pressure CP when the second charge amount CV2 is large. Thus, the control unit 100 determines the contact pressure CP of the charge removal unit 92 according to the charge amount CV of the transport belt 73 by referring to the map shown in FIG. Specifically, the control unit 100 determines the position of the charge removal unit 92 with respect to the transport belt 73.

  Further, in the printing apparatus 10 according to the present embodiment, if the medium M is a medium M that is easily bent, a part of the medium M is lifted on the conveyor belt 73 so that a part of the medium M contacts the print head 31. There is a risk. Alternatively, as the posture of the medium M changes, the ink ejected by the print head 31 may land on a position different from the original, which may reduce the printing accuracy. Therefore, in the present embodiment, the control unit 100, when the transport belt 73 transports the medium M that is easily bent, charges the charge amount CV of the transport belt 73 as compared to the case of transporting the medium M that is not easily bent. In order to increase the electrostatic attraction force to the medium M by the conveyor belt 73.

  Specifically, in the case where printing is performed on both sides of the medium M, the color material is applied to the medium M by performing printing compared to the case where printing is performed on one side of the medium M. The medium M may be easily bent by absorbing or adhering (in this embodiment, ink). Therefore, in the present embodiment, the control unit 100 increases the charge amount CV of the transport belt 73 when performing duplex printing on the medium M than when performing single-sided printing on the medium M.

  Here, the case where double-sided printing is performed may be a case where printing is performed on one side of the medium M and then printing is performed on the other side when printing is performed on the other side. In this case, when performing duplex printing, the amount of charge CV of the conveyor belt 73 is increased when printing on the other surface than when printing on one surface.

  Alternatively, the case where double-sided printing is performed may be both the case where printing is performed on one side of the medium M and the case where printing is performed on the other side. In this case, the charge amount CV of the transport belt 73 is increased when performing double-sided printing (printing on one side and printing on the other side) than when performing single-sided printing.

  Further, when the amount of ink discharged to the medium M increases, the medium M is easily bent because the medium M absorbs a large amount of ink. Therefore, in the present embodiment, the control unit 100 increases the charge amount CV of the transport belt 73 when the ink discharge amount to the medium M is large compared to when the ink discharge amount is small. The “ink discharge amount” here may be any ink discharge amount discharged to one medium M, and before printing is started based on a print job input to the printing apparatus 10. Then, the control unit 100 may calculate. In other words, the control unit 100 can be said to increase the amount of charge of the medium M when performing printing that consumes a large amount of ink, compared to when performing printing that consumes a small amount of ink.

  FIG. 6 shows a map showing the relationship between the ink discharge amount DA with respect to the medium M and the charge amount CV of the transport belt 73. According to the map shown in FIG. 6, the first charge amount CV1, which is the charge amount CV when the ink discharge amount DA to the medium M is the first discharge amount DA1, is greater than the first discharge amount DA1. The charge amount CV2 is less than the second charge amount CV2 when the second discharge amount DA2 is large. Thus, the control unit 100 determines the charge amount CV of the transport belt 73 according to the ink discharge amount DA with respect to the medium M by referring to the map shown in FIG.

  Further, since the ease of bending of the medium M is proportional to the thickness of the medium M, when the medium M is thin, it is easier to bend on the transport belt 73 than when the medium M is thick. Therefore, in the present embodiment, the control unit 100 increases the charge amount CV of the transport belt 73 when the thickness of the medium M is thin than when it is thick.

  FIG. 7 shows a map showing the relationship between the thickness Th of the medium M and the charge amount CV of the transport belt 73. According to the map shown in FIG. 7, the first charge amount CV1, which is the charge amount CV when the thickness Th of the medium M is the first thickness Th1, is a second thickness that is thicker than the first thickness Th1. It is larger than the second charge amount CV2 which is the charge amount CV when the thickness is Th2. Thus, the control unit 100 determines the charge amount CV of the transport belt 73 according to the thickness Th of the medium M by referring to the map shown in FIG.

  Note that when the type of the medium M is different, for example, when the medium M is made of paper and resin, the tendency of the medium M to bend with respect to the thickness Th of the medium M may be different. . Therefore, in this case, different maps may be used depending on the type of the medium M.

  In addition, when the distance (paper gap) between the print head 31 and the medium M is narrow, the medium M that has lifted from the transport belt 73 is transferred to the print head 31 even if the lift amount of the medium M from the transport belt 73 is small. There is a high possibility of contact. Therefore, in this embodiment, the control unit 100 increases the charge amount CV of the transport belt 73 when the interval is narrower than when the interval is wide.

  FIG. 8 shows a map showing the relationship between the interval PG between the print head 31 and the medium M and the charge amount CV of the transport belt 73. According to the map shown in FIG. 8, the first charge amount CV1, which is the charge amount CV when the interval PG between the print head 31 and the medium M is the first interval PG1, is larger than the first interval PG1. The charge amount CV2 is larger than the second charge amount CV2 when the second interval PG2 is wide. In this way, the control unit 100 determines the charge amount CV of the conveyance belt 73 according to the interval PG between the print head 31 and the medium M by referring to the map shown in FIG.

Note that the maps shown in FIGS. 5 to 8 show a linear relationship between the variable on the horizontal axis and the variable on the vertical axis, but may be a map having a non-linear relationship.
Next, the operation of the printing apparatus 10 of this embodiment will be described.

  As shown in FIG. 1, when printing is performed in the printing apparatus 10, the medium is transferred from the first medium supply unit 51, the second medium supply unit 52, or the third medium supply unit 53 to the electrostatic transport unit 70. M is supplied. In the electrostatic conveyance unit 70, the medium M is conveyed by the supply roller 81 and the conveyance belt 73, and ink is ejected from the print head 31 to the medium M conveyed by the conveyance belt 73, and printing is performed.

  Here, in this embodiment, the conveyance belt 73 wound around the first belt roller 71 and the second belt roller 72 is rotated by rotating the first belt roller 71. For this reason, as viewed from the first belt roller 71, in the rotational direction indicated by the solid line arrow in FIG. 2, the tension acting on the transport belt 73 on the upstream side (wiping unit 75 side) tends to increase, while the downstream side ( The tension acting on the conveyor belt 73 on the neutralization unit 82 side tends to be small.

  However, in the present embodiment, as illustrated in FIG. 3, the backup plate 74 and the charge removal unit 92 are paths that constitute the conveyance path among the circulation paths of the conveyance belt 73 and are upstream of the print head 31 in the conveyance direction. Is provided. The backup plate 74 urges the conveyor belt 73 from the inside to the outside, while the charge removal unit 92 urges the conveyor belt 73 from the outside to the inside.

  As a result, a conveyance resistance is applied to the conveyance belt 73 at a position upstream of the print head 31 in the conveyance direction, so that tension is applied to the conveyance belt 73 at a position downstream of the neutralization unit 92 in the conveyance direction and the conveyance belt 73 is slackened. Is less likely to occur. In the present embodiment, the contact pressure CP of the static eliminating unit 92 with respect to the conveyance belt 73 is uniform in the width direction X, so that the conveyance resistance acts uniformly on the medium M in the width direction X. It is possible to suppress the occurrence of partial sag.

  For this reason, when the transport belt 73 transports the medium M, the medium M whose posture is changed by being transported to the slack transport belt 73 comes into contact with the print head 31 or the print head 31 discharges the medium. Ink landing on a position different from the original is suppressed.

  When the transport belt 73 does not transport the medium M, the charge removal unit 92 removes electric charges from the outer surface 73b side of the transport belt 73, so that the electrostatic attraction force of the transport belt 73 to the print head 31 is weak. Is done. For this reason, the conveyance belt 73 in which the slack has occurred is suppressed from being adsorbed to the nozzle forming surface of the print head 31 by the electrostatic adsorption force.

  Furthermore, according to the present embodiment, the charge amount CV of the transport belt 73 is changed or the contact pressure CP of the charge removal unit 92 is changed according to the ease of bending of the medium M. For this reason, the electrostatic adsorption force with respect to the medium M by the conveyance belt 73 is insufficient, and the medium M is prevented from being lifted from the conveyance belt 73, and the generation of excessive electrostatic adsorption force is suppressed.

According to the above embodiment, the following effects can be obtained.
(1) The neutralization unit 92 that removes charges from the print surface Mb of the medium M electrostatically attracted to the conveyance belt 73 is provided upstream of the print head 31 in the conveyance direction. For this reason, when the transport belt 73 transports the medium M, the printing surface Mb of the medium M is neutralized, and the electrostatic attraction force of the transport belt 73 to the medium M is increased, so that the posture during transport of the medium M is increased. Can be stabilized. When the conveyance belt 73 does not convey the medium M, the outer surface 73b of the conveyance belt 73 is neutralized, and the electrostatic adsorption force of the conveyance belt 73 to the print head 31 is weakened. Can be prevented from adsorbing.

  Further, in the present embodiment, the backup plate 74 is provided at a position downstream of the charging roller 84 in the transport direction with respect to the facing position FP and the facing position FP. For this reason, a load resistance can be applied to the transport belt 73 by applying a load to the transport belt 73 in a direction intersecting the transport direction Y by the backup plate 74 and the charge removal unit 92. Therefore, even if the conveyor belt 73 is loosened in the transport direction upstream of the static elimination unit 92, the conveyor belt 73 is less likely to be loosened downstream of the static elimination unit 92 in the transport direction. In this way, it is possible to suppress the conveyance belt 73 from being attracted to the print head 31 by the electrostatic attraction force because the conveyance belt 73 is less likely to be loosened.

  (2) Since the backup plate 74 is made of a conductive material and grounded, charging of the conveyor belt 73 due to friction between the conveyor belt 73 and the backup plate 74 can be suppressed. As a result, it is possible to suppress a decrease in electrostatic attraction force with respect to the medium M by the conveyance belt 73 due to frictional charging of the conveyance belt 73.

  (3) Since the static elimination unit 92 includes the brush 91 that comes into contact with the printing surface Mb of the medium M electrostatically attracted to the conveyance belt 73, a configuration for removing charges from the printing surface Mb of the medium M with a simple configuration is realized. can do. In addition, compared with the case where the static elimination unit 92 is configured with a roller or the like, the contact area of the medium M with respect to the printing surface Mb can be easily increased, and the static elimination efficiency can be increased.

  (4) When the contact pressure CP of the static eliminating unit 92 is not uniform in the width direction X, there is a possibility that a part of the transport belt 73 in the width direction X is slack. In this regard, according to the present embodiment, the contact pressure CP of the static elimination unit 92 is uniform in the width direction X, and thus the occurrence of the above situation can be suppressed.

  (5) By adjusting the contact pressure CP of the static elimination unit 92 by the operating unit 93, when it is necessary to remove the charge from the printing surface Mb of the medium M such as when printing on the medium M, the contact pressure CP is decreased. On the other hand, when there is no need to remove charges from the printing surface Mb of the medium M, such as when printing is not performed on the medium M, the contact pressure CP can be decreased. For this reason, when it is not necessary to remove the electric charge from the printing surface Mb of the medium M, it is possible to suppress deterioration (for example, deformation) of the static eliminator 92 by continuing the state where the contact pressure CP is high. it can.

  (6) When the charge amount CV of the transport belt 73 is increased, the charge amount of the medium M contacting the transport belt 73 is also larger than when the charge amount CV is decreased. For this reason, in this case, if the charge removal on the printing surface Mb of the medium M is insufficient, the electrostatic adsorption force of the transport belt 73 to the medium M may be reduced.

  In this regard, in the present embodiment, when the charge amount CV of the transport belt 73 is increased, the contact pressure CP is made higher than when the charge amount CV is decreased, and more charges are transferred from the printing surface Mb of the medium M. Removed. Therefore, even when the charge amount CV of the transport belt 73 is increased, it is possible to suppress a decrease in electrostatic attraction force with respect to the medium M by the transport belt 73.

  Further, by increasing the contact pressure CP, the conveyance resistance acting on the conveyance belt 73 is increased, so that the conveyance belt 73 is not easily slackened, and when the medium M is not conveyed, the conveyance belt 73 is caused by the electrostatic adsorption force. The adsorption to the print head 31 can be suppressed.

  (7) When the medium M that is easily bent is conveyed, the medium M is curved on the conveyor belt 73 by increasing the charge amount CV of the conveyor belt 73 compared to the case where the medium M that is not easily bent is conveyed. It is possible to suppress lifting from the conveyor belt 73. That is, it is possible to prevent the medium M from coming into contact with the print head 31 and the ink from landing at a position different from the original due to the change in the posture of the medium M.

  (8) When printing is performed on both sides of the medium M, the medium M may be more easily curved than when printing is performed on one side of the medium M. In this regard, according to the present embodiment, when performing double-sided printing on the medium M, the amount of charge CV of the transport belt 73 is larger than when performing single-sided printing. It is possible to suppress lifting from the conveyor belt 73.

  (9) When the ink discharge amount DA with respect to the medium M increases, the medium M may be easily bent due to the large amount of ink absorbed by the medium M. In this regard, according to the present embodiment, when the ink discharge amount DA with respect to the medium M is large, the charge amount CV of the transport belt 73 is increased as compared with the case where the ink discharge amount DA is small. For this reason, it is possible to suppress the medium M from floating from the conveyance belt 73 regardless of the ink discharge amount DA with respect to the medium M.

  (10) Since the rigidity of the medium M becomes lower as the thickness Th of the medium M becomes thinner, the medium M is more easily bent on the transport belt 73 than when the medium M is thicker. In this regard, according to the present embodiment, when the thickness Th of the medium M is thin, the charge amount CV of the transport belt 73 is increased compared to when the medium M is thick, so that the medium M is transported regardless of the thickness Th of the medium M. Lifting from the belt 73 can be suppressed.

  (11) When the distance PG between the print head 31 and the medium M is narrow, the medium M lifted from the transport belt 73 contacts the print head 31 even when the lift amount of the medium M from the transport belt 73 is small. Is more likely to do. In this respect, according to the present embodiment, when the interval PG is narrow, the amount of charge CV of the conveyor belt 73 is increased compared to when the interval PG is wide, so that the medium M floating from the conveyor belt 73 contacts the print head 31. This can be suppressed.

  (12) The wiping unit 75 that wipes the outer surface 73b of the conveyance belt 73 is provided in a path that is not the conveyance path of the medium M among the circulation paths of the conveyance belt 73, so that the foreign matter (attachment) attached to the conveyance belt 73 is provided. ) Can be removed by the wiping unit 75. In this way, it is possible to suppress the electrostatic attraction force with respect to the medium M by the transport belt 73 from being reduced by the attached matter.

  (13) When the wiping unit 75 wipes the outer surface 73b of the conveyance belt 73, if the conveyance belt 73 is displaced in a direction away from the wiping unit 75, a portion where the conveyance belt 73 and the wiping unit 75 do not come into contact with each other occurs. There is a possibility that the outer surface 73b of the conveyor belt 73 cannot be wiped off normally. In this regard, according to the present embodiment, when the wiping unit 75 wipes the outer surface 73b of the conveyance belt 73, the clamping unit 78 contacts the inner surface 73a of the conveyance belt 73, so that the conveyance belt 73 and the wiping unit 75 and It is regulated by the clamping unit 78 so that the conveyance belt 73 is displaced in a direction away from the wiping unit 75. Therefore, when the wiping unit 75 wipes the transport belt 73, it is possible to easily remove the deposits on the transport belt 73.

In addition, you may change the said embodiment as shown below.
The charge amount CV of the conveyance belt 73 may not be changed according to the ease of bending of the medium M. In this case, it is desirable to set the charge amount CV of the conveyance belt 73 so that all the media M to be printed by the printing apparatus 10 can be attracted to the conveyance belt 73.

-The operation part 93 does not need to be provided. That is, the contact pressure CP of the static eliminating unit 92 with respect to the transport belt 73 (printing surface Mb of the medium M) may not be adjustable.
-The static elimination part 92 is good also as a static elimination roller which uses the width direction X as a rotating shaft direction.

  The printing apparatus 10 may be a serial inkjet printer that performs printing by ejecting ink toward the medium M from the print head 31 supported by a carriage that reciprocates in the width direction X.

The conveyance belt 73 may be wound around three or more belt rollers.
-The wiping part 75 and the clamping part 78 do not need to be provided.
The backup plate 74 may not be made of a conductive material or may not be grounded.

The charging roller 84 (charging unit) may AC-charge the conveyance belt 73. In this case, since the charge on the printing surface Mb side of the medium M is neutralized naturally, the neutralization unit 92 may not be provided.
Recording materials used for printing include fluids other than ink (liquids, liquids in which particles of functional materials are dispersed or mixed, liquids such as gels, and solids that can be jetted as fluids. ). For example, recording is performed by ejecting a liquid material in which a material such as an electrode material or a color material (pixel material) used for manufacturing a liquid crystal display, an EL (electroluminescence) display, and a surface emitting display is dispersed or dissolved. It may be configured.

  Further, the printing apparatus 10 includes a fluid ejecting apparatus that ejects a fluid such as a gel (for example, a physical gel), and a powder ejecting apparatus that ejects a solid such as toner (powder). (For example, a toner jet recording apparatus) may be used. In the present specification, the term “fluid” is a concept that does not include a fluid consisting only of gas. Examples of the fluid include liquid (inorganic solvent, organic solvent, solution, liquid resin, liquid metal (metal melt), etc. ), Liquids, fluids, powders (including granules and powders), and the like.

  As long as the printing apparatus 10 is a printer that heats the medium M, the printing apparatus 10 is not limited to a printer that performs recording by ejecting a fluid such as ink. For example, a laser printer, an LED printer, a thermal transfer printer (including a sublimation printer), and the like Non-impact printers, or impact printers such as dot impact printers may be used.

  The medium M is not limited to paper, but may be a fabric used for a plastic film, a textile printing apparatus, or the like.

  DESCRIPTION OF SYMBOLS 10 ... Printing apparatus, 11 ... Housing | casing, 12 ... Cover, 13 ... Insertion port, 20 ... Conveyance device, 30 ... Printing unit, 31 ... Print head, 32 ... Nozzle, 40 ... Discharge mechanism part, 41-45 ... Discharge roller , 46 ... driving roller, 47 ... driven roller, 48 ... discharge port, 49 ... mounting table, 50 ... feeding mechanism part, 51 ... first medium supply part, 52 ... second medium supply part, 53 ... third Medium feeding section, 54 ... first feeding roller, 55 ... feed cassette, 56 ... pickup roller, 57 ... separation roller, 58 ... second feeding roller, 61 ... first transport path, 62 ... first 2 transport paths, 63 ... third transport path, 64 ... branch mechanism, 65 ... branch transport roller, 66 ... reverse transport roller, 70 ... electrostatic transport section, 71 ... first belt roller, 72 ... second Belt roller 73 ... Conveying belt 73 ... conductive layer, 732 ... insulating layer, 73a ... inner surface, 73b ... outer surface, 74 ... backup plate (an example of a belt support part), 75 ... wiping part, 76 ... cleaning blade, 77 ... blade support part, 78 ... clamping part, DESCRIPTION OF SYMBOLS 81 ... Supply roller, 82 ... Drive roller, 83 ... Driven roller, 84 ... Charging roller (an example of a charging unit), 85 ... Power supply device, 86 ... Support roller, 90 ... Static elimination device, 91 ... Brush, 92 ... Static elimination unit, 93: Operating unit, 100: Control unit, CP: Contact pressure, CP1: First contact pressure, CP2: Second contact pressure, CV: Charge amount, CV1: First charge amount, CV2: Second charge Amount, DA ... discharge amount, DA1 ... first discharge amount, DA2 ... second discharge amount, FP ... opposite position, M ... medium, Ma ... back surface, Mb ... printing surface, P1 ... intermediate position, P2 ... center position , PG ... interval, P 1 ... first interval, PG2 ... second spacing, thickness ... Th, the first thickness ... Th1, a second thickness ... Th2, X ... width direction, Y ... conveying direction, Z ... vertical direction.

Claims (13)

An endless transport belt that electrostatically attracts the medium and rotates to transport the medium in the transport direction;
A print head that performs printing on a printing surface of the medium that is electrostatically attracted to the transport belt;
A neutralization unit that is disposed upstream of the print head in the transport direction and contacts the print surface of the medium to remove charges from the print surface of the medium;
A belt support portion that supports the conveyor belt by contacting the inner surface of the conveyor belt,
When the position facing the charge removal unit and the conveyor belt is the facing position,
The belt support unit is provided at at least one of the facing position and a position downstream of the facing position in the transport direction. The printing apparatus according to claim 1, wherein the belt support portion is made of a conductive material and is grounded. The printing apparatus according to claim 1, wherein the static elimination unit includes a brush that contacts a printing surface of the medium. The printing apparatus according to claim 1, wherein a contact pressure of the static eliminator with respect to the transport belt is uniform in a width direction intersecting the transport direction. The printing apparatus according to any one of claims 1 to 4, wherein a contact pressure of the charge removal unit with respect to the conveyance belt is adjustable. A control unit for controlling the charge amount of the conveyor belt;
The printing apparatus according to claim 5, wherein the control unit increases the contact pressure when the charge amount is increased than when the charge amount is decreased. The control unit increases the amount of charge when the transport belt transports the medium that is easily bent compared to when transporting the medium that is not easily bent. The printing apparatus as described in. The printing apparatus according to claim 7, wherein the control unit increases the charge amount when performing duplex printing on the medium as compared with performing simplex printing on the medium. The print head performs printing by ejecting ink onto the medium,
9. The control unit according to claim 7, wherein the control unit increases the charge amount when the ink discharge amount to the medium is large as compared with a case where the ink discharge amount is small. The printing apparatus as described. 10. The control unit according to claim 7, wherein when the thickness of the medium is thin, the control unit increases the charge amount as compared with a case where the thickness is large. The printing apparatus as described. 11. The control unit according to claim 7, wherein when the interval between the print head and the medium is narrow, the controller increases the amount of charge compared to when the interval is wide. A printing apparatus according to claim 1. The wiping unit for wiping the outer surface of the conveyance belt in a path that is not the conveyance path of the medium among the circulation paths of the conveyance belt is provided. The printing apparatus as described. When wiping the outer surface of the transport belt by the wiping unit, a gripping unit is provided that grips the transport belt along the width direction intersecting the transport direction together with the wiping unit by contacting the inner surface of the transport belt. The printing apparatus according to claim 12.

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