JP2007083490A - Platen, recording apparatus, and liquid jet apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent printing quality from deteriorating due to deformation (curving) caused when a lower end of paper is released from a carrying roller, or decrease the degree of the deterioration of the printing quality, in the case where borderless printing is applied particularly to the lower end part of the flexible paper, while proper printing can be done on a high-rigidity medium. <P>SOLUTION: First, second and third ribs 51, 52 and 53 are formed in order from the upstream side of a paper carrying passage, on the side, facing a recording head, of a platen which is provided in the state of facing the recording head for applying recording onto the paper and which specifies a gap between the paper and the recording head by supporting the paper. The protrusion of the third rib 53 to the side of the recording head is lower than the protrusions of the first and second ribs 51 and 52. This increases the action of pressing the paper against the platen by a recording-medium ejection means 5 and an auxiliary roller 43, and prevents the lower end of the paper from being lifted from the platen. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a platen provided opposite to a recording head for recording on a recording medium and defining a gap between the recording medium and the recording head by supporting the recording medium, and a recording apparatus including the platen. . The present invention also relates to a liquid ejecting apparatus.

Here, the liquid ejecting apparatus uses an ink jet recording head, and is not limited to a recording apparatus such as a printer, a copying machine, and a facsimile machine that discharges ink from the recording head to perform recording on a recording medium. And a device that ejects a liquid corresponding to the application from a liquid ejecting head corresponding to the ink jet recording head to an ejected medium corresponding to a recording medium, and adheres the liquid to the ejected medium. .
In addition to the recording head, as a liquid ejecting head, a color material ejecting head used for manufacturing a color filter such as a liquid crystal display, and an electrode material (conductive paste) used for forming an electrode such as an organic EL display or a surface emitting display (FED) Examples thereof include an ejection head, a bioorganic matter ejection head used for biochip production, and a sample ejection head as a precision pipette.

  An example of the recording apparatus or the liquid ejecting apparatus is an ink jet printer. An ink jet printer supports a printing paper from below at a position facing an ink jet recording head that discharges ink (liquid) onto a printing paper as a recording medium (jetting medium), and thereby a gap between the ink jet recording head and the printing paper. (Paper gap: hereinafter referred to as “PG”) is provided.

  Here, on the surface of the platen that faces the ink jet recording head, a plurality of ribs extending in the sub-scanning direction are provided at appropriate intervals in the main scanning direction. This is because the printing paper that swells by absorbing ink forms a wavy state (so-called “cockling state”) with a constant amplitude, so that the elongation due to swelling of the printing paper is absorbed between the ribs, thereby printing This is to make the distance between the surface and the inkjet recording head as uniform as possible.

  Here, the rib may be provided so as to be divided into an upstream side and a downstream side. For example, in a printer configured to perform so-called borderless printing, in which printing is performed without margins on the edge of the printing paper, a slot extending in the main scanning direction is formed so as to divide the rib. In addition, by ejecting ink to the part off the paper edge with the top or bottom of the paper placed in the slot, the borderless printing is performed on the paper edge, and the ink discharged to the part off the paper edge is discharged. It is designed to be discarded in the slot (for example, see Patent Document 1).

JP 2002-86821 A

  Here, the conveyance roller provided on the upstream side of the platen conveys the printing paper while pressing the printing paper against the platen. Further, if necessary, the printing paper can be pressed toward the platen by the discharge roller provided on the downstream side of the platen and the auxiliary roller provided in the vicinity of the upstream side. With this configuration, it is possible to prevent the printing paper from lifting from the platen, to prevent head rubbing and PG from changing, and to prevent deterioration in recording quality.

  By the way, when performing borderless printing on the lower end of the paper, even after the lower end of the paper is removed from the conveyance roller, the paper is sub-scanned and fed to the lower end of the paper by the discharge roller provided on the downstream side of the recording head. Perform recording. However, when the lower end of the paper is released from the strong restraint state by the conveying roller, the paper curls due to the initial curl of the paper or swelling due to ink absorption, and the PG changes, leading to a decrease in print quality, or It may cause head rubbing.

  In particular, in special paper having a coating layer on the printing surface, it is easy to bend due to the difference in expansion coefficient between the coating layer on the front surface and the base layer on the back surface, and in particular, it becomes convex upward due to swelling of the coating layer. Easy to bend. In the state where the paper is sandwiched between the conveying rollers as described above, a large curve does not occur due to the strong restraining force of the conveying roller. Along with this, the sheet is bent by the swelling action of the coating layer.

  On the other hand, as a means for preventing such a problem, it is conceivable to increase the pressing action of the discharge roller and the auxiliary roller against the sheet platen by shifting the position of the discharge roller upward. However, with this configuration, when recording is performed on a high-rigidity medium such as a board or an optical disk having a large paper thickness, the printing surface of the high-rigidity medium is not parallel to the head surface of the recording head. It becomes impossible to obtain a good print quality.

  Therefore, the present invention has been made in view of such a situation, and the problem is to perform borderless printing, particularly on the lower end portion of flexible paper, while enabling appropriate printing on a highly rigid medium. In this case, the lowering of the print quality is prevented by the deformation (curvature) generated when the lower end of the sheet is released from the conveying roller, or the degree of the decrease in the print quality is reduced.

  In order to solve the above-mentioned problem, a first aspect of the present invention is provided to face a recording head for recording on a recording medium, and by supporting the recording medium, the recording medium and the recording head A platen that defines a gap, and has a plurality of ribs extending in the sub-scanning direction at appropriate intervals in the main scanning direction on the side facing the recording head, the ribs including the first rib, A second rib provided on the downstream side of the first rib, and a third rib provided on the downstream side of the second rib, and a protrusion height of the third rib toward the recording head. Is lower than the protruding height of the first rib and the second rib.

  According to this aspect, since the protruding height of the third rib provided on the most downstream side toward the recording head is lower than the protruding height of the first rib and the second rib, the lower end of the recording medium is used as the platen. Thus, a space for pressing the recording medium more reliably is formed, that is, the lower end of the recording medium can be more reliably pressed toward the platen without shifting the position of the discharge roller upward. As a result, when performing borderless printing (especially the lower end) on a flexible recording medium while making it possible to perform appropriate recording on a highly rigid medium such as board paper or an optical disk, the lower end of the recording medium is It is possible to prevent the recording quality from being deteriorated due to deformation (curvature) generated when released from the conveying roller, or to reduce the degree of the deterioration of the recording quality.

The second aspect of the present invention is characterized in that the second rib is formed so as not to protrude toward the recording head with respect to the first rib.
According to this aspect, since the second rib is formed so as not to protrude toward the recording head with respect to the first rib, when the upper end of the recording medium reaches the second rib from the first rib. The tendency of the upper end to move upward, that is, toward the recording head can be reduced or prevented. As a result, it is possible to prevent the upper end of the recording medium from rubbing against the recording head and fouling the upper end of the recording medium, or to prevent the recording quality from deteriorating due to nonuniform PG.

  According to a third aspect of the present invention, in the first or second aspect, the rib is disposed at a position that supports both side end portions of a recording medium having a specific size from below in the main scanning direction. In addition, the protruding height of the rib supporting the both side end portions of the recording medium toward the recording head is larger than the protruding height of the other rib supporting the recording medium from below between the both side end portions. It is characterized by being low.

  According to this aspect, the protruding height of the rib supporting the both side end portions of the recording medium toward the recording head is the same as the protruding height of the other rib supporting the recording medium from below between the both side end portions. Therefore, when the recording medium is deformed so that the central portion is convex toward the recording head (for example, the recording medium is a recording medium having a recording surface formed by a coating layer, and the coating layer absorbs moisture). Even when the recording surface swells), the distance between the recording surface and the recording head can be secured, and head rubbing or the like can be prevented.

According to a fourth aspect of the present invention, there is provided a recording head for recording on a recording medium, a recording medium conveying means provided on the upstream side of the recording head, and conveying the recording medium to the recording head side, A recording medium discharging means provided on the downstream side of the recording head and discharging a recording medium on which recording has been performed; a recording medium provided opposite to the recording head and supporting the recording medium; The platen according to any one of claims 1 to 3, which defines a gap with the recording head.
According to this aspect, in the recording apparatus, it is possible to obtain the same effects as the first to third aspects described above.

According to a fifth aspect of the present invention, there is provided the auxiliary roller according to the fourth aspect, wherein the auxiliary roller is positioned between the recording head and the recording medium ejecting means and is rotated in contact with the recording surface of the recording medium. When the conveyance path of the recording medium is viewed from the side, the contact point of the auxiliary roller with the recording medium is located in a direction away from the recording head rather than the tops of the first rib and the second rib. It is characterized by that.
According to this aspect, when the conveyance path of the recording medium is viewed from the side, the contact point of the auxiliary roller with the recording medium is farther from the recording head than the tops of the first rib and the second rib. Since the auxiliary roller and the discharge roller are positioned in the direction, the recording medium (particularly the lower end portion) can be reliably pressed against the platen.

  According to a sixth aspect of the present invention, there is provided a liquid ejecting head that ejects liquid onto the ejected medium, and an ejected medium that is provided upstream of the liquid ejecting head and conveys the ejected medium toward the liquid ejecting head. Positioned between the transporting means, the ejected medium discharging means provided on the downstream side of the liquid ejecting head, for discharging the ejected medium on which the liquid has been ejected, and the liquid ejecting head and the ejected medium ejecting means. And an auxiliary roller that is driven to rotate in contact with the liquid ejection surface of the ejected medium and the liquid ejecting head, and supports the ejected medium, thereby forming a gap between the ejected medium and the liquid ejecting head. A rib that supports a medium to be ejected from below on a side facing the liquid ejecting head at an appropriate interval in the main scanning direction. Multiple The rib is provided on the downstream side of the first rib extending in the sub-scanning direction, the second rib provided on the downstream side of the first rib, extending in the sub-scanning direction, and the second rib. A third rib extending in the sub-scanning direction, and a protrusion height of the third rib toward the liquid jet head is lower than the protrusion height of the first rib and the second rib. It is characterized by being.

  Hereinafter, embodiments of the present invention will be described with reference to FIGS. 1 to 7. Here, FIG. 1 is an external perspective view of the main body of the printer 1 (with the outer case removed), FIG. 2 is a sectional view of the same side, and FIG. 4 is a cross-sectional side view of the same, FIG. 5 is a schematic diagram showing the positional relationship of the first rib 51, the second rib 52, and the third rib 53. FIGS. 6 and 7 are the transport driven roller 31 and the first rib 51. FIG. 6 is a plan view showing a positional relationship among the second rib 52, the third rib 53, and the discharge driving roller 41.

  Hereinafter, an outline of an ink jet printer (hereinafter referred to as “printer”) 1 as an example of a recording apparatus or a liquid ejecting apparatus according to the present invention will be described first with reference to FIGS. 1 and 2. In the following, the right direction in FIG. 2 and the left direction in FIGS. 4 and 5 (the front side of the printer) are referred to as the “downstream side” of the paper transport path, and the left direction in FIG. 2 and the right direction in FIGS. (Back side of the printer) is referred to as “upstream side”.

  The printer 1 includes a feeding device 2 capable of setting a recording sheet (mainly cut sheet paper: hereinafter referred to as “sheet P”) as an example of “recording medium” and “ejection medium” in an inclined posture at the rear part, The paper P is fed from the feeding device 2 toward the recording medium conveying means 4 on the downstream side. The fed paper P is conveyed (sub-scan feed) by the recording medium conveying means 4 to the recording means 3 on the downstream side, and recording is executed. Then, the sheet P on which recording is performed by the recording unit 3 is discharged to the front of the apparatus by the recording medium discharge unit 5 on the downstream side.

Hereinafter, components on the paper conveyance path of the printer 1 will be described in more detail. The feeding device 2 includes a hopper 11, a feeding roller 12, a retard roller 13, a return lever 14, a paper support 15, an auxiliary support 16, a movable edge guide 17, and a fixed edge guide 19. Configured.
The hopper 11 is formed of a plate-like body, and is provided so as to be able to swing around an upper swing fulcrum (not shown). By swinging, the paper P supported in an inclined posture is fed onto the hopper 11. The pressure contact posture that presses against the roller 12 and the separation posture that separates from the feeding roller 12 are switched. The feeding roller 12 has a substantially D shape when viewed from the side, and feeds the uppermost sheet P pressed by the arc portion to the downstream side, while the recording medium after the sheet P is fed. During conveyance of the paper P by the conveyance means 4, the flat portion is controlled to face the paper P as shown in the figure so as not to cause a conveyance load.

  The retard roller 13 has an outer periphery formed of an elastic material, is provided so as to be able to press contact with the arc portion of the feed roller 12, and is provided in a state where a predetermined rotational resistance (torque) is applied. When the retard roller 13 is fed with only one sheet without the double feeding of the paper P, a torque greater than the rotational resistance is applied to the retard roller 13, so that the retard roller 13 is driven to rotate with respect to the feed roller 13. (Clockwise in FIG. 2). On the other hand, when a plurality of sheets P exist between the feeding roller 12 and the retard roller 13, the friction coefficient between the sheets is lower than the friction coefficient between the sheet P and the retard roller 13, so that the retard roller No torque greater than the rotational resistance is applied to 13, and the motor 13 stops without rotating. Therefore, this prevents the next and subsequent sheets P, which are to be double-fed by the uppermost sheet P to be fed, from traveling from the retard roller 13 to the downstream side, thereby preventing double feeding.

The return lever 14 is provided so as to be swingable when viewed from the side of the feeding path of the paper P. By swinging, the return lever 14 returns the next and subsequent paper P about to be double fed onto the hopper 11. Play.
The paper support 15 and the auxiliary support member 16 (FIG. 1) support the rear end of the paper P by extending the paper support surface of the hopper 11 toward the rear end of the paper P.
The movable edge guide 17 and the fixed edge guide 19 are provided so as to face each other in the hopper 11 and abut against the edge of the paper P to regulate the position of the edge. The movable edge guide 17 is provided in the hopper 11 so as to be displaceable (slidable) in the width direction of the paper P, and thus can be displaced to an appropriate position suitable for the width dimension of the paper P.

  Reference numerals 17a and 19a denote restricting portions formed on the movable edge guide 17 and the fixed edge guide 19, respectively. The restricting portions 17a and 19a serve to guide the paper P when the paper P is set, and further, the maximum number of sheets P (allowed) to be supported by the hopper 11 (set in the feeding device 2). The maximum number of sheets).

Next, a detecting means (not shown) for detecting the passage of the paper P is formed between the feeding device 2 and the recording medium conveying means 4, and a paper P feeding posture is formed and the paper P is fed. A guide roller 26 is provided for preventing contact with the feed roller 12 and reducing the transport load.
The recording medium transport unit 4 provided on the downstream side of the feeding device 2 includes a transport drive roller 30 that is rotationally driven by a motor, and a transport driven roller 31 that is driven to rotate while being in pressure contact with the transport drive roller 30. Configured. The transport driving roller 30 is provided with an adhesion layer formed by substantially uniformly dispersing wear-resistant particles on the outer peripheral surface of a metal shaft extending in the paper width direction, and the transport driven roller 31 has a low friction material such as an elastomer on the outer peripheral surface. A plurality of the drive driving rollers 30 are arranged in the axial direction.

  In this embodiment, two transport driven rollers 31 are pivotally supported at the downstream end of the paper guide top 24 so as to be freely rotatable. Three paper guide tops 24 are provided in the paper width direction as shown in FIG. Side by side. The top 24 of the paper guide is provided so that the shaft 24a is pivotally supported by the main frame 23 so as to be swingable about the shaft 24a as viewed from the side of the paper transport path, and the transport driven roller 31 is provided by the coil spring 25. It is urged in a direction in which it comes into pressure contact with the conveyance drive roller 30.

The sheet P that has reached the recording medium conveying means 4 is sub-scanned to the recording means 3 on the downstream side when the conveyance driving roller 30 rotates while being nipped by the conveyance driving roller 30 and the conveyance driven roller 31. Is done.
The recording unit 3 includes an inkjet recording head (hereinafter referred to as “recording head”) 36 and a paper guide lower 50 (a platen 56) provided so as to face the recording head 36. The recording head 36 is provided at the bottom of the carriage 33, and the carriage 33 is guided by a carriage guide shaft 34 extending in the main scanning direction (paper width direction: front and back direction in FIG. 2), and is driven by a drive motor (not shown) in the main scanning direction. It is driven to reciprocate. In addition, the carriage 33 is equipped with an independent ink cartridge 35 for each of a plurality of colors, and supplies ink to the recording head 36.

  A first rib 51, a second rib 52, and a third rib 53 are formed on a surface facing the recording head 36 on the sheet guide bottom 50 (platen 56) that defines the distance between the sheet P and the recording head 36. At the same time, grooves 54 and 55 for discarding the ink are formed, and the ink ejected to the area deviated from the edge of the paper P is discarded into the grooves 54 and 55, so that printing can be performed without a margin on the edge of the paper P. The so-called borderless printing is performed. In the grooves 54 and 55, an ink absorbing material 29 (see FIG. 3) for absorbing ink is disposed. The configuration of the paper guide lower 50 will be described in detail later.

  Subsequently, an auxiliary roller 43 and a recording medium discharge unit 5 are provided on the downstream side of the recording head 36. The auxiliary roller 43 is provided on the paper conveyance path from the area where the recording head 36 and the platen 56 face each other to the recording medium discharge means 5 so as to be driven and rotated in contact with the recording surface of the paper P. It functions to prevent the platen 56 from lifting and keep the distance between the paper P and the recording head 36 constant (details will be described later). The recording medium discharge means 5 includes a discharge drive roller 41 that is rotationally driven by a motor (not shown), and a discharge driven roller 42 that rotates in contact with the discharge drive roller 41.

  In the present embodiment, a plurality of discharge driving rollers 41 are provided in the axial direction of the rotating shaft 40 that is made of a rubber roller and is rotationally driven. In this embodiment, the position of the auxiliary roller 43 in the main scanning direction is provided between the position of the discharge driving roller 41 and the two ribs (details will be described later).

  A toothed roller having a plurality of teeth on the outer periphery is used for the discharge driven roller 42 (the same applies to the auxiliary roller 43), and the discharge frame Assy 45 having a long shape in the main scanning direction corresponds to the plurality of discharge drive rollers 41. A plurality are provided. The paper P on which recording has been performed by the recording means 3 is driven forward by the discharge drive roller 41 while being nipped by the discharge drive roller 41 and the discharge driven roller 42, so that the paper P is directed toward the front of the apparatus (not shown). Discharged.

  The general configuration of the printer 1 is as described above. The printer 1 is not limited to a cut sheet as a recording medium or an ejection medium, but an optical disk (thin plate-like body) such as a CD-R, or a highly rigid medium such as a board paper. It is configured to be capable of direct ink jet recording. A tray guide 7 shown in FIG. 1 supports a high-rigidity medium such as a tray (not shown) on which an optical disk is set and board paper, and the high-rigidity medium is supported by a tray guide 7 provided in front of the apparatus. In the meantime, the recording head 36 performs ink jet recording while being manually inserted into the paper conveyance path toward the rear side (upstream side) of the printer 1 and sub-scan fed by the recording medium conveyance means 4.

The outline of the printer 1 has been described above. Hereinafter, the paper guide 50 and its peripheral components will be described in detail.
As shown in FIGS. 3 and 4, the lower paper guide 50 is integrally provided with a platen 56 on the downstream side from the transport driving roller 30 and a rear paper guide 57 on the upstream side from the transport driving roller 30, and transport driving is performed. The roller 30 and the discharge drive roller 41 are integrally formed of a resin material so that the rotation shaft 40 can be supported.

  The platen 56 is provided at a position facing the recording head 36 and supports the paper P from below, thereby defining the distance (PG) between the paper P and the recording head 36 and guiding the paper P downstream. . The rear paper guide 57 guides the paper P fed from the feeding device 2 to the transport driving roller 30.

  On the side of the platen 56 facing the recording head 36, a plurality of ribs extending in the sub-scanning direction are provided at appropriate intervals in the main scanning direction. The ribs are constituted by four types of ribs of a first rib 51, a second rib 52, a third rib 53, and a fourth rib 58 in order from the upstream side in the sub-scanning direction. That is, the first rib 51 extending in the sub-scanning direction is provided in the vicinity of the downstream side of the transport driving roller 30, and the second rib 52 extending in the sub-scanning direction with the groove 54 interposed on the downstream side of the first rib 51, Further, on the downstream side of the second rib 52, third ribs 53 extending in the sub-scanning direction with the groove 55 interposed therebetween are provided.

  As shown in FIG. 3, a plurality of first ribs 51, second ribs 52, and third ribs 53 are provided at appropriate intervals in the main scanning direction, and support the paper P from below to define PG. The fourth ribs 58 are disposed on both sides of the discharge driving roller 41 and guide the recorded paper P between the discharge driving roller 41 and the discharge driven roller 42.

  In the recording head 36, the range indicated by reference numeral S indicates the range in which ink discharge nozzles (not shown) are formed in the sub-scanning direction. As shown in the drawing, the second rib 52 is within the ink discharge nozzle formation range. The first rib 51 and the third rib 53 are located outside the ink discharge nozzle formation range.

  As described above, the groove 54 extending in the main scanning direction is formed between the first rib 51 and the second rib 52, and similarly, between the second rib 52 and the third rib 53, the main scanning direction is formed. A groove 55 extending in the direction is formed. The groove 54 and the groove 55 are for discarding ink ejected from the upper end or the lower end of the paper P, that is, in a state where the upper end of the paper P is disposed above the groove 55. Ink droplets are ejected to the upper end of P and the part off the upper end. As a result, borderless recording is performed on the upper end of the sheet P, and ink droplets that have been removed from the upper end of the sheet P are discarded in the groove 55. In addition, in a state where the lower end of the paper P is disposed above the groove 54, ink droplets are ejected to the upper end of the paper P and a portion off the upper end. As a result, borderless recording is performed on the lower end of the paper P, and ink droplets that have fallen from the lower end of the paper P are discarded in the groove 54.

  Next, the height relationship between the first rib 51, the second rib 52, and the third rib 53 will be described with reference to FIG. In FIG. 5, the first rib 51, the second rib 52, the third rib 53, the recording medium conveying means 4, the recording head 36, the auxiliary roller 43, and the recording medium discharging means 5 are shown in FIG. In order to make the positional relationship in the direction easy to understand, the positional relationship in the vertical direction is exaggerated.

  In FIG. 5, a symbol Lr indicates a straight line (a common tangent line between the two rollers) connecting a contact point of the transport driving roller 30 with the paper P and a contact point of the discharge driving roller 30 with the paper P. . Further, symbol A is the distance between the top of the second rib 52 and the straight line Lr, symbol B is the gap between the top of the second rib 52 and the top of the third rib 53, and symbol C is the contact point of the paper P on the auxiliary roller 43. A gap between the first rib 53 and the top of the third rib 53 is shown. Further, symbol a indicates the distance of the sheet conveyance path from the downstream end of the top of the second rib 52 to the auxiliary roller 43, and symbol b indicates the distance of the sheet conveyance path from the auxiliary roller 43 to the recording medium discharge means 5. Yes. In addition, symbol α indicates an angle formed by a straight line connecting the shaft core of the transport driving roller 30 and the shaft core of the transport driven roller 31 and a line orthogonal to the straight line Lr, and symbol β indicates a discharge driving roller. An angle formed by a straight line connecting the shaft core of 41 and the shaft core of the discharge driven roller 42 and a line orthogonal to the straight line Lr is shown.

  In FIG. 5, the axis of the conveyance driven roller 31 is arranged on the downstream side (left side in FIG. 5) of the sheet conveyance path with respect to the axis of the conveyance drive roller 30, and thereby a straight line passing through the axis of both rollers. Has an inclination angle α as shown in the figure. Similarly, the shaft axis of the discharge driven roller 42 is arranged on the upstream side of the paper transport path (the right side in FIG. 5) with respect to the shaft core of the discharge driving roller 41, and thereby a straight line passing through the shaft cores of both rollers. However, it has an inclination angle β as shown in the figure. As a result, a curved posture is formed between the recording medium conveying means 4 and the recording medium conveying means 5 so that the sheet P is convex downward, and the sheet P is pressed against each rib of the platen 56, Lifting from the platen 56 is prevented.

  Here, the sheet clamping pressure between the conveyance driving roller 30 and the conveyance driven roller 31 is strong, and the recording head 36 is connected between the recording medium conveyance unit 4 and the recording medium discharge unit 5. Therefore, even at the stage before the upper end of the sheet reaches the recording medium ejecting means 5, the upper end of the sheet is relatively strongly pressed against the platen 56 and is at a position facing the recording head 36. Lifting from the platen 56 is prevented.

  However, at the lower end of the sheet, the sheet clamping pressure by the discharge drive roller 41 and the discharge driven roller 42 cannot be set large (because roller marks are formed by the teeth on the outer periphery of the discharge driven roller 42), and the recording medium discharge means 5 Since the distance between the recording head 36 and the recording head 36 is long, it is difficult to sufficiently obtain the pressing action of the paper P against the platen 56 only by the recording medium discharge means 5. Accordingly, the auxiliary roller 43 is used to press the paper P toward the platen 56, thereby preventing the lower end of the paper P from being lifted from the platen 56 even after the lower end of the paper P is detached from the recording medium conveying means 4. Yes.

  However, for example, when the paper P is a dedicated paper having a coating layer on the recording surface, the paper P is likely to be curved (curl) due to a difference in expansion coefficient between the front surface coating layer and the back surface base layer. In particular, since the coating layer is easily deformed so as to protrude upward due to swelling of the coat layer, the lower end of the paper P is released from the recording medium conveying means 4, that is, released from the strong restraining force by the recording medium conveying means 4. In this case, the paper P may be curved, leading to a decrease in recording quality due to head rubbing or PG change.

  In order to solve such a problem, the position of the recording medium discharge means 5 is positioned between the recording medium discharge means 5 and the auxiliary roller 43 in order to press the paper P toward the platen 56 more reliably. It is conceivable to shift upward. However, if configured in this way, the straight line Lr is inclined with respect to the head surface of the recording head 36, and this leads to a decrease in recording quality when recording is performed on a highly rigid medium that is not easily bent such as the optical disk or board. There is a fear.

Therefore, in the present embodiment, the protruding height of the third rib 53 toward the recording head 36 is set lower than the protruding height of the first rib 51 and the second rib 52.
More specifically, in this embodiment, the top of the first rib 51 and the top of the second rib 52 are formed at substantially the same level, whereas the top of the third rib 53 is the first rib 51. And a position lower than the top of the second rib 52 by the gap B. That is, the protruding height of the third rib 53 toward the recording head 36 is lower than the protruding height of the first rib 51 and the second rib 52. That is, a space for pressing the lower end of the sheet toward the platen 56 more reliably is formed.

Thus, the contact point of the auxiliary roller 43 with the paper P can be arranged in a direction away from the recording head 36 rather than the tops of the first rib 51 and the second rib 52 (gap C < B).
As described above, the pressing action of the recording medium discharge means 5 and the auxiliary roller 43 against the platen 56 of the paper P can be strengthened, and the lifting of the paper P from the platen 56 can be prevented more reliably, and in particular, the lower end of the paper can be prevented. It is possible to prevent the deformation of the sheet when released from the strong restraint state of the transport driving roller 30 and the transport driven roller 31, or to reduce the degree of the deformation.

  Since the contact point of the paper P on the auxiliary roller 43 is lower than the top of the second rib 52, when the paper leading edge reaches the auxiliary roller 43 from the second rib 52, the paper leading edge assists. It is easy to come into contact (collision) with the roller 43, and therefore it is desirable to make the distance a in the figure as large as possible. Further, since the gap between the nip point between the discharge driving roller 41 and the discharge driven roller 42 and the contact point of the auxiliary roller 43 with the paper P is large, the leading edge of the paper passing through the auxiliary roller 43 can be smoothly and smoothly. It is desirable that the top portion of the fourth rib 58 be inclined as shown in the figure between the distance b in the figure so that it is nipped between the discharge driving roller 41 and the discharge driven roller 42. In this embodiment, from such a viewpoint, the distance a is set to 19 to 21 mm. The distance b is set to 20 to 22 mm, the gap B is set to about 0.5 mm, and the gap C is set to about 0.35 mm.

  In this embodiment, the recording medium discharge means 5 and the auxiliary roller 43 are configured to press the paper P against the platen 56. However, the recording medium discharge means 5 alone has a sufficient pressing effect on the paper P. If so, the auxiliary roller 43 is not necessary. That is, even in the configuration without the auxiliary roller 43, the above-described effects are obtained by configuring the protruding height of the third rib 53 toward the recording head 36 to be lower than the protruding height of the first rib 51 and the second rib 52. Can be obtained.

  By the way, in the present embodiment, the first rib 51 and the second rib 52 are formed so that the tops thereof are at substantially the same level, but the second rib 52 protrudes from the first rib 51 toward the recording head 36. The manufacturing error is controlled so that it does not occur. That is, when the second rib 52 protrudes from the first rib 51 toward the recording head 36, when the upper end of the sheet reaches the second rib 52 from the first rib 51, the advancing direction of the upper end of the sheet is directed upward. As a result, the upper end of the sheet may be rubbed against the recording head 36, so the second rib 52 is formed so as not to protrude toward the recording head 36 with respect to the first rib 51.

  Subsequently, with reference to FIGS. 6 and 7, the positions of the transport driven roller 31, the first rib 51, the second rib 52, the third rib 53, the discharge driving roller 4, and the auxiliary roller 43 in the main scanning direction. The relationship will be described. In FIGS. 6 and 7, only the above-described components are drawn for simplifying the drawings, and other components are omitted. In the following, the three ribs (first rib 51, second rib 52, and third rib 53) having the same position in the main scanning direction are collectively referred to as “rib R”.

  When the paper P swells by absorbing ink and expands, the distance between the recording surface of the paper P and the recording head 36 tends to be uneven. Therefore, normally, in an ink jet printer, the wavy state (cockling state) in which the extension between the two ribs R is released, that is, the ribs R are at the peaks and the two ribs R are at the valleys is forced. Thus, even when the paper P is extended, the distance between the recording surface and the recording head 36 is made as uniform as possible.

In the present embodiment, in order to reliably form such a cockling state without complicating the apparatus, the above-described components are arranged as follows.
That is, in FIG. 6A (and FIG. 7A), the symbol F indicates a position where one end 25a (see FIG. 3) of the coil spring 25 presses the paper guide top 24 toward the transport driving roller 30. As shown in the figure, the coil spring 25 biases the intermediate portion of the two transport driven rollers 31 on the paper guide 24.

  That is, the position F is a position where the load concentrates when the paper P is pinched by the transport driving roller 30 and the transport driven roller 31, and this position becomes a trough when the cock ring is formed on the paper P. easy. Therefore, using this property, the position F is set to a valley portion when cockling is formed on the paper P, and the position between the two ribs R arranged at an appropriate interval in the main scanning direction is set. F is arranged.

  As a result, as schematically shown in FIG. 6B, a cock ring is formed on the paper P, with the position of the rib R as a mountain and the position F where the load is concentrated as a valley. Accordingly, it is possible to reliably cause a cockling forming action on the paper P without incurring a complicated structure and an increase in cost, and it is possible to prevent a decrease in recording quality.

  In particular, until the upper end of the sheet reaches the recording medium discharge means 5, the upper end of the sheet is not subjected to the binding force from the recording medium discharge means 5, so that it is generally difficult to form a cockling state. Since the position F where the load is concentrated when the paper P is pinched by the transport driving roller 30 and the transport driven roller 31 is arranged between the two ribs R, the transport driving roller 30 and the transport driven roller 31 are arranged. As a result, a cockling forming action also occurs at the upper end of the sheet due to the cooperative action with the rib R, and a cockling state can be formed on the sheet P even before the upper end of the sheet reaches the recording medium discharge means 5. In other words, it is possible to prevent the recording quality from being deteriorated due to head rubbing at the upper end of the paper or PG change.

  Note that the cockling state formed on the paper P can further suppress the variation in PG as the number of peaks and valleys increases, that is, as the cockling cycle is shorter. Therefore, as shown in FIGS. 7A and 7B, a larger number of positions F and ribs R where loads are concentrated when the paper P is pinched by the transport driving roller 30 and the transport driven roller 31 are provided. By shortening the cockling cycle, it is possible to further prevent the recording quality from deteriorating.

Further, in the embodiment shown in FIG. 7, since the positions F and the ribs R where the load concentrates are alternately arranged, the crest and trough portions are alternately and regularly formed, and more reliably. A decrease in recording quality can be prevented.
In addition, in the case of A4 size dedicated paper having a coat layer with a thickness of 0.2 to 0.3 mm, it is known that the best recording quality can be obtained by forming six valleys as shown in FIG. .

  Further, the amount of elongation caused by the paper P absorbing and swelling the ink tends to be larger in the central portion of the paper than in the paper side end portion. In view of such a property, it is also effective to make the cockling cycle (interval between the two ribs R) in the central portion of the paper shorter than the cockling cycle in the paper side end portion.

  By the way, when the sheet P is deformed so that the central portion is convex toward the recording head 36 (for example, when the recording surface is a sheet formed by a coat layer and the coat layer is swollen by moisture absorption). ), The central portion of the sheet tends to cause a drop in recording quality due to head rubbing or PG change. Therefore, in the present embodiment, the protruding height of the rib R supporting the both end portions of the paper P of a specific size toward the recording head 36 is set, and the other ribs supporting the paper P from below between the both end portions. It is formed lower than the protruding height of R.

Specifically, in FIG. 6, reference numerals L ₁ and L ₈₀ indicate positions through which both side edges of A4 size paper (width 210 mm) pass, and ribs at positions that support both side edges of this A4 size paper. R protrusion height of the recording head 36 side (code a ₁ and ribs R formed in the range shown by a ₃₎ is lower than the protrusion height of the other ribs R. Similarly, the range in the present embodiment shown the rib R (code A ₂ in a position where one side of the side edge of the L-size paper (width 89 mm) and 4 × 6 size paper (width 101.6 mm) passes Similarly, the formed rib R) has a protruding height toward the recording head 36 that is lower than the protruding height of the other ribs R. Reference numeral L ₁ is a position where the side edge of one side of the paper of all sizes to pass through.

As described above, even if the center of the sheet is deformed (curled) so as to protrude toward the recording head 36, the distance between the recording surface and the recording head 36 can be secured, and the recording quality is deteriorated due to head rubbing or PG change. Can be prevented.
The embodiment described above is an example, and the arrangement and recording of the ribs R in the main scanning direction according to various conditions such as the type of paper to be used and the nature of the ink without departing from the gist of the present invention. The height relationship of each rib (the first rib 51, the second rib 52, and the third rib 53) with respect to the head 36 can be adjusted.

1 is an external perspective view of an apparatus main body of a printer according to the present invention. 1 is a side sectional view of a printer according to the present invention. The perspective view of the principal part of the recording means centering on under paper guidance. FIG. 4 is a side sectional view of a recording unit centered under a paper guide. The schematic diagram which shows the positional relationship of a 1st rib, a 2nd rib, and a 3rd rib. The top view which shows the arrangement | positioning relationship of a conveyance driven roller, each rib, and a discharge drive roller. The top view which shows the arrangement | positioning relationship of a conveyance driven roller, each rib, and a discharge drive roller.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Inkjet printer, 2 Feeding device, 3 Recording means, 4 Recording medium conveyance means, 5 Recording medium discharge means, 10 Friction member, 11 Hopper, 12 Feeding roller, 13 Retarding roller, 13a Rotating shaft, 14 Paper return Lever, 15 Paper support, 16 Auxiliary support member, 17 Movable edge guide, 19 Fixed edge guide, 23 Main frame, 24 On paper guide, 25 Coil spring, 26 Guide roller, 30 Transport drive roller, 31 Transport driven roller, 33 Carriage , 34 Carriage guide shaft, 35 Ink cartridge, 36 Recording head, 40 Rotating shaft (of discharge drive roller), 41 Discharge drive roller 41 Discharge driven roller, 43 Auxiliary roller, 45 Discharge frame Assy, 50 Under paper guide, 51 1st rib, 52 2nd rib, 53 Third rib 53, 55 Groove, 56 Platen, 57 Rear paper guide, 58 Fourth rib, P Recording paper

Claims (6)

A platen provided opposite to a recording head for recording on a recording medium and defining a gap between the recording medium and the recording head by supporting the recording medium,
On the side facing the recording head, it has a plurality of ribs extending in the sub-scanning direction at appropriate intervals in the main scanning direction,
The rib is a first rib;
A second rib provided on the downstream side of the first rib;
A third rib provided on the downstream side of the second rib, and
A platen, wherein a protruding height of the third rib toward the recording head is lower than a protruding height of the first rib and the second rib. 2. The platen according to claim 1, wherein the second rib is formed so as not to protrude toward the recording head with respect to the first rib. 3. The ribs according to claim 1, wherein the ribs are disposed at positions to support both side end portions of a recording medium having a specific size in the main scanning direction from below, and support both side end portions of the recording medium. A platen characterized in that the protruding height of the rib toward the recording head is lower than the protruding height of the other ribs that support the recording medium from below between the both side end portions. A recording head for recording on a recording medium;
A recording medium conveying means provided on the upstream side of the recording head and conveying the recording medium to the recording head;
A recording medium discharging means provided on the downstream side of the recording head and discharging a recording medium on which recording has been performed;
The platen according to any one of claims 1 to 3, wherein the platen is provided to face the recording head and defines a gap between the recording medium and the recording head by supporting the recording medium. A recording apparatus characterized by that. In Claim 4, provided with an auxiliary roller which is located between the recording head and the recording medium discharge means, and is rotated in contact with the recording surface of the recording medium,
When the conveyance path of the recording medium is viewed from the side, the contact point of the auxiliary roller with the recording medium is located in a direction away from the recording head rather than the tops of the first rib and the second rib. ,
A recording apparatus. A liquid ejecting head for ejecting liquid onto the ejected medium;
An ejected medium transport unit that is provided upstream of the liquid ejecting head and transports the ejected medium toward the liquid ejecting head;
An ejected medium discharging means provided on the downstream side of the liquid ejecting head, for discharging the ejected medium on which the liquid has been ejected;
An auxiliary roller that is positioned between the liquid ejecting head and the ejected medium discharge means and is rotated in contact with the liquid ejecting surface of the ejected medium;
A liquid ejecting apparatus comprising: a platen provided to face the liquid ejecting head and defining a gap between the ejected medium and the liquid ejecting head by supporting the ejected medium,
The platen has a plurality of ribs that support the ejected medium from below on the side facing the liquid ejecting head at an appropriate interval in the main scanning direction,
A first rib extending in the sub-scanning direction;
A second rib provided on the downstream side of the first rib and extending in the sub-scanning direction;
A third rib provided on the downstream side of the second rib and extending in the sub-scanning direction;
The protruding height of the third rib toward the liquid jet head is formed lower than the protruding height of the first rib and the second rib.
A liquid ejecting apparatus.

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