JP2005138305A - Recording medium transfer mechanism and inkjet recording apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To solve an image quality defect due to waving of a recording paper sheet by preventing decrease in a suction force for holding the recording paper sheet on a rib at the time when a leading end and a rear end of the recording paper sheet are printed in an inkjet recording apparatus which transfers the recording paper sheet by a predetermined band width to a scanning region of a recording head. <P>SOLUTION: A recess part 45 is formed by a plurality of the ribs 42 arranged along a transfer direction of the recording paper sheet P, and a partition plate 46 set in a direction orthogonal to the transfer direction between the ribs 42. A suction hole 44 is formed at the recess part 45. The lower side of the suction hole 44 communicates with a suction duct 50, and the interior of the suction duct 50 is made a negative pressure by a suction fan 52. At the time of printing the leading end or the rear end of the recording paper sheet P, the air is sucked from the suction hole 44 of the recess part 45, so that the suction force enough to the recording paper sheet P is generated. A distance between the recording paper sheet P and the recording head 14 is kept constant accordingly. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a recording medium transport mechanism provided in a print area of an ink jet recording head (hereinafter referred to as a recording head) that ejects ink droplets, and an ink jet recording apparatus using the recording medium transport mechanism.

  Conventionally, a recording head is mounted on a carriage that reciprocates in a direction orthogonal to the conveyance direction of the recording medium, and conveyance of the recording medium every predetermined pitch and reciprocation of the carriage (recording head scanning) are repeated alternately. However, an ink jet recording apparatus that discharges ink droplets from the nozzles of the recording head and records (prints) an image based on desired image data on a recording medium is known.

  In this ink jet recording apparatus, a recording medium is conveyed to a scanning area (printing area) of a recording head, an ink droplet is ejected from a nozzle to print an image with a predetermined bandwidth, and then the recording medium is A recording medium conveying means for conveying is provided.

  As shown in FIGS. 7 and 8, the recording medium conveying unit is provided with a platen 102 in the scanning area of the recording head 100 where the recording medium P is sent out by the conveying roller 110 and the pinch roller 112. A plurality of ribs 104 are provided on the upper surface of the platen 102 along the conveyance direction of the recording medium P, and a plurality of suction holes 106 are formed between the ribs 104 along the conveyance direction. A chamber 107 is provided on the back side of the suction hole 106, and a negative pressure is generated by the suction fan 108. By setting the chamber 107 to a negative pressure, air is sucked from the suction holes 106 and the recording medium P conveyed on the ribs 104 is sucked.

In addition, a discharge roller 114 and a spur 116 that sandwich and convey the recording medium P are disposed on the downstream side of the scanning area of the recording head 100 in the conveying direction. With this configuration, the recording medium P is conveyed with a predetermined bandwidth (for example, see Patent Document 1).
JP 2001-347710 A

  In the ink jet recording apparatus shown in FIGS. 7 and 8, the recording medium P is adsorbed to the ribs 104 by the plurality of suction holes 106 formed between the ribs 104, and the distance between the recording medium P and the recording head 100 is kept constant. I am doing so.

  However, this ink jet recording apparatus has a problem that a suction force is not sufficiently generated for the recording medium P when the leading edge and the trailing edge of the recording medium P are printed. That is, as shown in FIG. 9, when the leading end of the recording medium P is on the upstream side of the platen 102, the downstream suction hole 106 communicates with the atmosphere, and on the upstream side, air is released from the gap between the rib 104 and the conveying roller 110. Is sucked. For this reason, the attractive force with respect to the recording medium P decreases.

  On the other hand, as shown in FIG. 10, when the rear end of the recording medium P is on the downstream side of the platen 102, the upstream suction hole 106 communicates with the atmosphere, and on the downstream side, the gap between the rib 104 and the discharge roller 114 Air is sucked from. For this reason, the attractive force with respect to the recording medium P decreases. Therefore, as compared with the state where the recording medium P extends over the entire surface of the platen 102, the distance between the recording medium P and the recording head cannot be kept constant, and image quality defects occur due to the waviness of the recording medium. Such a problem is particularly likely to occur when the nozzle width of the recording head is increased.

  The present invention has been made in view of the above problems, and can maintain a constant distance between the recording medium and the recording head even when printing the leading edge or the trailing edge of the recording medium, thereby preventing the occurrence of image quality defects. It is an object of the present invention to provide a recording medium transport mechanism and an ink jet recording apparatus that can perform the above-described operation.

  In order to achieve the above object, a recording medium transport mechanism according to the invention described in claim 1 is provided in a print area of a recording head that ejects ink droplets, and a platen from which a recording medium is sent out by a transport roller; A plurality of ribs that are provided on the upper surface of the platen along the conveyance direction of the recording medium at predetermined intervals and support the recording medium, and the ribs are partitioned in a direction perpendicular to the conveyance direction of the recording medium. A partition plate forming a portion, a suction hole formed in the recess, and suction means for generating a suction force in the suction hole.

  According to the first aspect of the present invention, a recess is formed by the rib provided along the conveyance direction of the recording medium and the partition plate provided in the direction orthogonal to the conveyance direction, and a suction hole is formed in the depression. ing. Then, by sucking air from the suction hole by the suction means, a suction force is generated with respect to the recording medium conveyed to the recess, and the recording medium is adsorbed on the rib. For this reason, even when printing the leading edge or trailing edge of the recording medium, air does not easily flow from the outside into the indented portion, so that a sufficient suction force is generated on the recording medium, and the recording medium and the recording medium are recorded. The distance from the head is kept almost constant. Therefore, it is possible to prevent the occurrence of image quality defects due to the undulation or sinking of the recording medium.

  According to a second aspect of the present invention, in the configuration according to the first aspect, a plurality of the recessed portions are provided in the conveyance direction of the recording medium.

  According to the second aspect of the present invention, since a plurality of indentations are provided in the recording medium conveyance direction, air is sucked from the suction holes formed in the plurality of indentations. For this reason, even when a part of the front end or the rear end of the recording medium is on the rib, the recording medium can be more reliably adsorbed on the rib, and the distance between the recording medium and the recording head can be kept substantially constant.

  According to a third aspect of the present invention, in the configuration according to the first or second aspect, the upper surface of the partition plate is lower than the upper surface of the rib.

  In the invention according to claim 3, since the upper surface of the partition plate is formed lower than the upper surface of the rib, the recording medium is formed in a direction perpendicular to the conveying direction when the recording medium is conveyed on the rib with a predetermined bandwidth. The formed partition plate prevents the leading end of the recording medium from being caught.

  According to a fourth aspect of the present invention, in the configuration according to the first to third aspects, the upstream side surface of the partition plate in the conveyance direction of the recording medium is inclined to the downstream side.

  In the invention according to claim 4, since the upstream side surface of the partition plate is inclined toward the downstream side, even if the partition plate is provided in a direction orthogonal to the transport direction, the leading end of the recording medium is upstream of the partition plate. It is conveyed along the side slope. For this reason, it is prevented that the front-end | tip part of a recording medium catches on a partition plate.

  According to a fifth aspect of the present invention, an ink jet recording apparatus includes the recording medium conveying mechanism according to the first to fourth aspects.

  In the ink jet recording apparatus according to the invention described in claim 5, since the recording medium transport mechanism according to claims 1 to 4 is provided, even when the leading or trailing end of the recording medium is printed by the recording head, Air is sucked from the suction holes formed in the recesses, and a sufficient suction force is generated for the recording medium. For this reason, the distance between the recording medium and the recording head is kept substantially constant, and the occurrence of image quality defects due to the waviness of the recording medium is prevented.

  According to the recording medium transport mechanism and the ink jet recording apparatus of the present invention, a sufficient suction force is generated with respect to the recording medium even when the leading or trailing end of the recording medium is printed, and the distance between the recording medium and the recording head. Can be kept almost constant. For this reason, it is possible to prevent the occurrence of image quality defects due to the undulation of the recording medium.

  Hereinafter, a first embodiment of the present invention will be described in detail with reference to the drawings.

  First, the outline of the inkjet recording apparatus 10 will be described first, and then the main part according to the present invention will be described. The recording medium will be described as recording paper P. In FIG. 2, the direction orthogonal to the transport direction of the recording paper P in the inkjet recording apparatus 10 is represented by an arrow M as the main scanning direction, and the transport direction is represented by an arrow S as the sub-scanning direction.

  As shown in FIG. 4, the inkjet recording apparatus 10 includes a carriage 12 on which a recording head 14 is mounted. On the upstream side of the carriage 12 in the conveyance direction of the recording paper P (hereinafter simply referred to as “upstream side”), a shaft 16 is installed in the main scanning direction. A part of the timing belt 18 that travels in the main scanning direction is fixed to the carriage 12. Thereby, the carriage 12 is supported on the shaft 16 so as to be reciprocally movable in the main scanning direction.

  Further, the inkjet recording apparatus 10 is provided with a paper feed tray 20 in which recording paper P before image printing is bundled, and an image is printed by the recording head 14 above the paper feed tray 20. A paper discharge tray 22 for discharging the recorded recording paper P is provided. A recording paper transport device 30 is provided for transporting the recording paper P fed one by one from the paper feed tray 20 at a predetermined pitch in the sub-scanning direction facing the recording head 14.

  The ink jet recording apparatus 10 is provided with a control panel 24 for performing various settings during printing. As shown in FIG. 4, black, cyan, magenta, and yellow recording heads 14 are interchangeably mounted on the carriage 12 of the inkjet recording apparatus 10. As shown in FIG. 2, the recording heads 14 for the respective colors are mounted on the carriage 12 so that the nozzles 15 provided on the recording head 14 face the platen 32.

  As shown in FIGS. 1 to 3, the platen 32 holds the recording paper P on which the ink droplets are ejected from the nozzles 15 of the recording head 14 to form an image flat.

  On the upstream side of the platen 32 in the conveyance direction of the recording paper P, a conveyance roller 34 that is rotatably supported is provided, and a driving force is transmitted by a driving unit (not shown). A plurality of pinch rollers 36 are pivotally supported at a predetermined interval at a position facing the conveyance roller 34, and rotate following the conveyance roller 34. The recording paper P is nipped and conveyed by the rotation of the conveying roller 34 and the pinch roller 36. A discharge roller 38 and a plurality of spurs 40 driven to rotate by the discharge roller 38 are provided downstream of the platen 32 in the conveyance direction of the recording paper P, and the recording paper P on which an image is formed is discharged. To do.

  As shown in FIG. 3, the recording paper transport device 30 is provided with a suction duct 50 below the platen 32, and a suction fan 52 that makes the suction duct 50 have a negative pressure below the suction duct 50. Is provided. On the upper surface of the platen 32, ribs 42 are arranged in parallel along the conveying direction of the recording paper P at predetermined intervals. Further, a partition plate 46 is provided on the upper surface of the platen 32 to partition between the ribs 42 in a direction orthogonal to the conveyance direction of the recording paper P and form a recess 45.

  The hollow 45 is provided with a suction hole 44 that communicates with the suction duct 50 and sucks air. Each partition plate 46 is formed with an inclined surface 46a in which the upstream side surface in the recording paper conveyance direction is inclined to the downstream side.

  Further, in order to prevent the leading edge of the recording paper P from being caught by the partition plate 46, the upper surface of the partition plate 46 is formed to be 0.3 mm to 0.8 mm lower than the upper surface of the rib 42. Further, the distance from the upper surface of the rib 42 to the surface of the recessed portion 45 is set to about 1 mm to 2.5 mm so that the recording paper P does not block the suction hole 44 due to the negative pressure due to suction. This is because when the recording paper P blocks the suction hole 44, the ink penetrates to the back side of the recording paper P due to the suction force, which causes image quality defects during double-sided printing.

  Next, the operation of the present invention in the ink jet recording apparatus 10 as described above will be described.

  The recording paper P is transported at a predetermined bandwidth in the sub-scanning direction while being sandwiched between the transport roller 34 and the pinch roller 36, the discharge roller 38 and the spur 40 on the upstream side and the downstream side of the recording head 14. . As shown in FIG. 3, in the scanning area of the recording head 14, the recording paper P is transported on the ribs 42, and suction force is applied to the recording paper P by sucking air from the suction holes 44 by the suction fan 52. The arrow A) in FIG. As a result, the recording paper P is attracted onto the ribs 42, and the distance between the recording head 14 and the recording paper P is kept substantially constant.

  As shown in FIGS. 2 and 4, the recording head 14 moves on the shaft 16 in the main scanning direction while ejecting ink droplets from the nozzles 15 onto the recording paper P, thereby achieving a predetermined bandwidth. An image is formed.

  When one movement in the main scanning direction is completed, the recording paper P is conveyed by the conveying roller 34 and the pinch roller 36, the discharge roller 38 and the spur 40 with a predetermined bandwidth in the sub scanning direction, and again the recording head. An image is printed with a predetermined bandwidth while 14 moves in the main scanning direction (the direction opposite to the above). By repeating such an operation a plurality of times, an image based on the image data is recorded on the recording paper P.

  In such an ink jet recording apparatus 10, as shown in FIG. 5, when printing the leading edge of the recording paper P, the indented portion 45 on the downstream side in the transport direction communicates with the atmosphere, but the indented portion on the upstream side in the transport direction. 45 is a space substantially closed by the recording paper P, so that air is sucked by the suction hole 44 and a sufficient adsorbing force (arrow B in FIG. 5) is generated on the leading end of the recording paper P. To do. For this reason, the leading end portion of the recording paper P is adsorbed on the rib 42, and the distance between the recording head 14 and the recording paper P is kept substantially constant. Therefore, it is possible to prevent the occurrence of image quality defects due to the undulation of the recording paper P. Further, the amount of the recording paper P sinking between the ribs 42 is limited, and it is possible to prevent ink from penetrating the back side of the recording paper P and causing image quality defects during double-sided printing.

  On the other hand, as shown in FIG. 6, when printing the trailing edge of the recording paper P, the upstream indentation 45 communicates with the atmosphere, but the downstream indentation 45 has one abbreviation by the recording paper P. Since it is a closed space, air is sucked by the suction hole 44 and a sufficient suction force (arrow C in FIG. 6) is generated on the rear end portion of the recording paper P. Therefore, the rear end portion of the recording paper P is adsorbed on the rib 42, and the distance between the recording head 14 and the recording paper P is kept substantially constant. Therefore, it is possible to prevent the image quality from being deteriorated due to the undulation of the recording paper P and the sinking between the ribs 42.

  Further, the upper surface of the partition plate 46 is formed to be lower than the upper surface of the rib 42, and an inclined surface 46a in which the upstream side surface is inclined downstream. For this reason, when the recording paper P is conveyed on the rib 42, it is possible to prevent the leading end portion of the recording paper P from being caught by the partition plate 46.

  In the present embodiment, the three partition plates 46 are provided in the conveyance direction of the recording paper P to form the two recesses 45, but three or more recesses may be provided. Conversely, even if one recess is formed by two partition plates, the suction effect is improved as compared with the conventional case. In the present embodiment, one suction hole 44 is provided in each recess 45, but a plurality of suction holes may be provided. By increasing the number of suction holes and partition plates, the distance between the recording paper and the recording head can be more reliably kept constant when printing the leading or trailing edge of the recording paper.

  The ink jet recording apparatus 10 of the present embodiment as described above records an image (including characters) on the recording paper P, but is not limited to this. That is, the recording medium is not limited to paper, and the liquid to be ejected is not limited to ink. For example, it is industrially useful to create color filters for displays by discharging ink onto polymer films or glass, or to form bumps for component mounting by discharging solder in a welded state onto a substrate. It is included in all droplet ejecting apparatuses used.

1 is a perspective view showing a recording paper transport device of an ink jet recording apparatus according to a first embodiment of the present invention. 1 is a plan view showing a recording paper transport device of an ink jet recording apparatus according to a first embodiment of the present invention. 1 is a cross-sectional view illustrating a recording paper transport device of an ink jet recording apparatus according to a first embodiment of the present invention. 1 is a partially broken schematic perspective view showing an ink jet recording apparatus according to a first embodiment of the present invention. It is a figure which shows operation | movement of the recording paper conveyance apparatus at the time of printing the front-end | tip of recording paper with the inkjet recording device which concerns on 1st Embodiment of this invention. FIG. 5 is a diagram illustrating an operation of the recording paper transport device when printing the trailing edge of the recording paper by the ink jet recording apparatus according to the first embodiment of the present invention. It is sectional drawing which shows the recording paper conveyance direction in the recording paper conveyance apparatus of the conventional inkjet recording device. It is sectional drawing which shows the scanning direction of the recording head in the recording paper conveying apparatus of the conventional inkjet recording device. It is a figure which shows operation | movement of the recording paper conveyance apparatus at the time of printing the front-end | tip of recording paper with the conventional inkjet recording device. It is a figure which shows operation | movement of the recording paper conveying apparatus at the time of printing the rear end of recording paper with the conventional inkjet recording device.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Inkjet recording device 14 Recording head 15 Nozzle 16 Pinch roller 30 Recording paper conveyance device 32 Platen 34 Conveyance roller 36 Pinch roller 38 Discharge roller 40 Spur 42 Rib 44 Suction hole 45 Recessed portion 46a Inclined surface 46 Partition plate 50 Suction duct 52 Suction fan

Claims (5)

A platen provided in a print area of a recording head that discharges ink droplets, and a recording medium is sent out by a conveying roller;
A plurality of ribs provided on the upper surface of the platen at predetermined intervals along the conveyance direction of the recording medium, and supporting the recording medium;
A partition plate for partitioning the ribs in a direction perpendicular to the conveyance direction of the recording medium, and forming a recess;
A suction hole formed in the recess,
A suction means for generating a suction force in the suction hole;
A recording medium conveying mechanism comprising:   The recording medium transport mechanism according to claim 1, wherein a plurality of the recessed portions are provided in the transport direction of the recording medium.   The recording medium transport mechanism according to claim 1, wherein an upper surface of the partition plate is lower than an upper surface of the rib.   The recording medium transport mechanism according to any one of claims 1 to 3, wherein an upstream side surface of the partition plate in the transport direction of the recording medium is inclined toward the downstream side.   An ink jet recording apparatus comprising the recording medium transport mechanism according to claim 1.

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